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"Rust" and "Dirt" for Artificial Photosynthesis
As a close cousin to rust, hematite is the mineral name of alpha phase iron oxide. It possesses a host of properties desired for solar energy harvesting such as stability against photocorrosion, suitable bandgap for maximized energy conversion, and abundance for large-scale implementations. Finding an efficient solar water splitting method to mine electron-rich hydrogen for clean power has been thwarted by the poor performance of hematite, particularly in successfully pumping up the energy of excited electrons. But by "re-growing" the mineral's surface, a smoother version of hematite more than doubled electrical yield, opening a new door to energy-harvesting artificial photosynthesis, according to a report published online today in the journal Nature Communications by Associate Professor Dunwei Wang and his team.
Re-grown hematite proved to be a better power generating anode, producing a record low turn-on voltage that enabled the researchers to be the first to use earth-abundant hematite and silicon (which is derived from dirt) as the sole light absorbers in artificial photosynthesis. The new hydrogen harvesting process achieved an overall efficiency of .91 percent. The result offers new hope that efficient and inexpensive solar fuel production by readily available natural resources is within reach.
To read the article, go to: http://www.nature.com/ncomms/2015/150616/ncomms8447/abs/ncomms8447.html
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A Caged Probe for Global Monitoring of Cysteine Reactivity in Living Cells
Cysteine residues on proteins are susceptible to an array of posttranslational modifications (PTMs), including oxidation, nitrosation and lipid adduction. Cysteine-reactive chemical probes can be coupled with mass spectrometry (MS) to globally monitor these PTMs and identify the site and stoichiometry of modification. The high reactivity and toxicity of existing cysteine-targeted probes precludes their use in living cells. Many cysteine PTMs are highly labile and are often disrupted by cell lysis, necessitating methods to study these modifications directly within the context of living cells. To globally monitor cysteine reactivity directly in living cells, Assistant Professor Eranthie Weerapana and Postdoctoral Research Associate Masahiro Abo, developed a caged electrophilic probe that can be activated in situ upon irradiation. This caged-bromoketone (BK) probe is non-toxic to cells at high micromolar concentrations and can be activated with both temporal and spatial control upon 5 minutes of UV irradiation. The caged-BK probe was applied to monitor cysteine oxidation events that accompany the activation of cells with growth factors such as the epidermal growth factor (EGF). Binding of EGF to its cognate receptor EGFR generates a burst of hydrogen peroxide, which oxidizes a variety of cellular cysteine residues. Using quantitative MS, cysteine residues known to form redox-active disulfides and sulfenic acids, were found to be oxidized upon cellular EGF stimulation. This platform sets the stage for identifying and quantifying sites of cysteine modification upon treatment with cellular oxidants, cysteine-targeted small-molecule inhibitors and thiophilic metal ions under physiologically relevant conditions.
To read the article, go to: http://pubs.acs.org/doi/abs/10.1021/jacs.5b04350
Chasing Bacteria with Covalent Chemistry
The emergence of pathogenic bacteria that are resistant to conventional antibiotics poses a serious threat to the health of mankind. New diagnostic and therapeutic strategies are needed to combat these bacterial pathogens, for which it is essential to differentiate bacteria from mammalian cells. In their recent article published in Nature Communications, Associate Professor Jianmin Gao and coworkers describe a novel strategy that allows exclusive labeling of bacteria in blood serum. Bacterial cells are known to display a different set of lipids in their membranes in comparison to their mammalian counterparts. Previous work in the field has focused on the use of cationic peptides to target anionic lipids enriched on bacterial cell surfaces. This approach has seen limited success as the charge-charge attraction can be easily weakened by the presence of salt and other biomolecules. The new paper from the Gao group show that certain bacterial lipids, specifically the amine-presenting lipids including phosphatidylethanolamine (PE) and lysyl phosphatidylglycerol (Lys-PG), can be selectively derivatized to form iminoboronates. As amine-presenting lipids are scarce on the surface of mammalian cells, their modification via iminoboronate chemistry allows specific labeling of bacterial cells. Importantly, the iminoboronate formation is quickly reversible under physiologic conditions, which makes it a powerful strategy for targeting biomolecules of interest as modification of unintended targets can be quickly reversed and avoided. Considering the large number of bacterial species that present PE and/or Lys-PG on their surfaces, the covalent labeling strategy reported by Gao and coworkers should find a wide range of applications in diagnosis of bacterial infections and delivery of antibiotic agents.
To read the article, go to: http://www.nature.com/ncomms/2015/150312/ncomms7561/full/ncomms7561.html
Materials for Better Batteries
With record-high theoretical capacities, lithium oxygen battery promises a post-Li-ion energy storage technology that may enable electrical vehicles with driving ranges beyond 500 miles. Presently the development of this technology faces a number of challenges, with the poor stability and low charge/discharge efficiency being on the top of the list. These issues are recognized as a result of parasitic reactions between carbon support and the electrolyte with reactive intermediates such as peroxide and superoxide ions. In the summer of 2014, Associate Professor Dunwei Wang's team demonstrated a strategy to circumvent the stability issue by replacing the current collector with a true carbon-free material of the TiSi2 nanonet (J. Am. Chem. Soc. 2014, 136, 8903). Given the ubiquitous presence of carbon in energy storage devices, its ease of preparation and low cost, however, it is impractical to abandon carbon altogether. Recently, the same team, in collaboration with Assistant Professor Wei Fan of the University of Massachusetts at Amherst, developed a new strategy to address the issue. By coating the carbon surface with a thin but uniform layer of metal oxide using a technique known as atomic layer deposition, the team report in w that the carbon support can be effectively separated from the reactive species. The desired properties of structural support and charge transport by carbon are preserved. As a result, the lifetime of the battery is increased by 325%, while the efficiency is improved by 18%.
To read the article, go to: http://dx.doi.org/10.1002/anie.201410786
High-value alcohols and higher-oxidation-state compounds by catalytic Z-selective cross-metathesis
Olefin metathesis provides access to molecules that are indispensible to research in chemistry, biology and medicine. Despite the recent discovery of catalysts that promote Z-selective reactions, an important persisting problem has been the lack of transformations that directly generate acyclic Z allylic alcohols. This shortcoming extends to products that contain a hindered neighboring substituent and/or reactive and ubiquitous functional units such as a phenol, an aldehyde, or a carboxylic acid. In a recent report in the journal Nature (2015, 517, 181–186; doi:10.1038/nature14061) Professor Amir Hoveyda and graduate studens Ming Joo Koh, Kashif Khan, Miao Yu and Malte Mikus together with postdoctoral associate Dr. Sebastian Torker report on the design of a Ru complex that is uniquely effective in generating the aforementioned compounds by cross-metathesis processes. The complex is prepared from a commercially available Ru-based precursor and an easily generated air-stable zinc catechothiolate. Transformations typically proceed with 5.0 mol % of the complex and an inexpensive reaction partner in 4–8 hours under ambient conditions; products are obtained in up to 80% yield and 98:2 Z:E selectivity. Utility is demonstrated by application to synthesis of naturally occurring anti-tumor agent neopeltolide and a single-step stereoselective gram-scale conversion of a renewable feedstock (oleic acid) to an anti-fungal agent.
To view the publication see: http://www.nature.com/nature/journal/v517/n7533/full/nature14061.html
Bis-BN Cyclohexane: A Remarkably Kinetically Stable Chemical Hydrogen Storage Material
A critical component for the successful development of fuel cell applications is hydrogen storage. For back-up power applications, where long storage periods under extreme temperatures are expected, thermal stability of the storage material is particularly important. In their recent communication from the Journal of the American Chemical Society, Professor Shih-Yuan Liu and his coworkers at Boston College, in collaboration with team members at the Pacific Northwest National Laboratory (PNNL) and The University of Alabama describe the synthesis and characterization of an unusually kinetically stable chemical hydrogen storage material with a H2 storage capacity of 4.7 wt%. The compound, which is the first reported parental BN isostere of cyclohexane featuring two BN units, is thermally stable up to 150 °C both in solution and as a neat material. Yet, it can be activated to rapidly desorb H2 at room temperature in the presence of a catalyst without releasing other detectable volatile contaminants. Furthermore, the team also intercepted and structurally characterized two cage compounds with the unique S4 symmetry that were also formed during the H2 desorption process. The remarkable kinetic stability exhibited by this new compound (a.k.a Bis-BN cyclohexane) and the ability to readily release its stored H2 content under mild conditions would make it a potentially suitable candidate for stationary fuel cell applications. Overall, this work provides a new approach for the development of thermally stable chemical hydrogen storage materials and is establishing the potential for Bis-BN cyclohexane to serve as a monomer for new polymeric architectures.
To view the publication see: http://pubs.acs.org/doi/abs/10.1021/ja511766p
Two BN Isosteres of Anthracene: Synthesis and Characterization
Acenes, or linear benzofused polyaromatics, are a distinct class of polycyclic aromatic hydrocarbons (PAHs) with favorable properties for use in organic materials applications. By replacing an aromatic carbon-carbon bond with an isosteric boron-nitrogen bond (BN/CC isosterism), it is possible to create new chemical space and impart new functions that are distinct from the ones exhibited by corresponding classic carbonaceous PAHs. In their recent article from the Journal of the American Chemical Society, Professor Shih-Yuan Liu and co-workers, in collaboration with the group of Professor Anna Chrostowska (Universitéde Pau et des Pays de l'Adour, France) synthesized two BN isosteres of anthracene, a simple acene containing three fused benzene rings. The authors demonstrate that BN/CC isosterism lowers the energy of the frontier orbitals of the anthracene framework, significantly increasing its stability. This property is important when considering materials for organic optoelectronic materials, since higher acenes often deleteriously react when used in organic electronics under ambient conditions, causing a decrease in performance. Interestingly, the researchers found that despite the changes in frontier orbital energies, the optical properties of the BN anthracenes remain similar to that of the all- carbon anthracene. The work demonstrates that BN/CC isosterism can be used as a molecular design strategy to improve the stability of acene-type structures while maintaining the photophysical characteristics of this important family of compounds.
To view the publication see: http://dx.doi.org/10.1021/ja508813v
Catalytic Enantioselective Multicomponent Assembly
Efficient catalytic reactions that generate C–C bonds enantioselectively and those that produce trisubstituted alkenes diastereoselectively are central to research in modern chemistry. Transformations that accomplish these tasks simultaneously in a single operation are scarce and highly prized; this is particularly the case if the catalysts, substrates and reagents are easily accessed at low cost and reactions are simple to set and conditions are conditions are mild. In an Article in this week's issue of Nature, Professor Amir Hoveyda and graduate students Fanke Meng and Kevin McGrath report a facile multicomponent catalytic process that begins with a chemo-, site- and diastereoselective copper–boron addition to a monosubstituted allene. The resulting boron-substituted organocopper intermediates then participate in a chemo-, site- and enantioselective allylic substitution. Products, which contain a stereogenic carbon center, a mono-substituted alkene and an easily modifiable Z-trisubstituted alkenylboron group, are obtained in up to 89% yield, with >98% branch- and stereoselectivity and >99:1 enantiomeric ratio. The copper-based catalyst is derived from a robust heterocyclic salt that can be prepared in multi-gram quantities from inexpensive starting materials and without costly purification procedures. Utility of the approach is showcased through exceptionally concise enantioselective synthesis of gram quantities of natural products rottnestol (member of an antibiotic family) and herboxidiene (anti-tumor). In the case of rottnestol, the overall yield is seven times better than the best formerly reported approach, and herboxidiene is accessed in nearly twice the total yield of the most efficient previous route.
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A discussion on the significance of the paper's findings by Professor Phil S. Baran and graduate student Matthew T. Villaume, Scripps Research Institute, appears in Nature: News and Views; To read the article, go to:
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Molecular Encapsulation beyond the Aperture Size Limit through Dissociative Linker Exchange in Metal–Organic Framework Crystals
Incorporating functional guest molecules into the cavities of crystalline porous materials makes it possible to engineer these materials for drug delivery, sensing, electrical conductivity, luminescence, and energy conversion. Recently, attention has been drawn to a molecular-type class of crystalline porous materials, metal-organic frameworks (MOFs) due to their chemically tunable pore surfaces, their comparatively mild syntheses, and their unique properties such as framework flexibility, postsynthetic modification, and exchangeable ligands. Despite these advances, approaches for incorporating large and more diverse guests into MOFs are still limited. In a recent report in the Journal of the American Chemical Society, a team led by Professors Frank Tsung and Jeff Byers introduce a new concept for incorporating larger and more diverse guest molecules into MOFs. In this approach, they take advantage of ligand exchange reactions to "open" part of the framework of the pre-synthesized MOF crystals. Expanded apertures created by the ligand exchange process allow large guest molecules to diffuse into the MOF pore. After guest incorporation, association of the ligand closes the large aperture, trapping the guest molecule in the MOF pore. This new approach to guest incorporation is expected to be general because framework ligand exchange has been carried out under various conditions and exists in a large number of MOFs with diverse secondary building units. An additional practical advantage of decoupling encapsulation and MOF synthesis is that MOF production can be scaled-up independently of guest loading, which is especially relevant since several MOFs, such as ZIF-8, Fe-BTC,
HKUST-1, and MIL-53(Al), have been become commercially available.
To view the publication, see: http://pubs.acs.org/doi/abs/10.1021/ja5054779
Surfactant-Directed Atomic to Mesoscale Alignment: Metal Nanocrystals Encased Individually in Single-Crystalline Porous Nanostructures
IIn colloidal syntheses, it is a challenge to control the lattice alignment at the interface between materials with crystal lattices in disparate scales, such as those between metal lattices and microporous or mesoporous materials, where the structural parameters can differ by orders of magnitude; however, the alignment is highly desired for many applications. In a recent report in the Journal of the American Chemical Society, Professor Frank Tsung and coworkers address this challenge by a new concept inspired by studies on self-assembled monolayers (SAM). By using self-assembled surfactant layers, they have aligned the lattices at the interface in a proof-of-concept structure, a core-shell nanocomposite with a well-defined metal nanocrystal core and a metal-organic-framework (MOF) shell. This system is representative because the metal and MOF lattices differ in structural dimensions by orders of magnitude. This is the first example of utilizing self-assembled molecules in colloidal syntheses to align crystalline materials from the atomic scale to the mesoscale. The alignment is essential for follow-up studies on the diffusion and orientation of molecules in such structures which will be investigated via spectroscopic analysis and catalysis experiments.
To view the publication, see: http://dx.doi.org/10.1021/ja5048522
Organoboron Transformations via Boron-Stabilized Carbanions
Organoboron compounds can be readily converted to a range of valuable products and are thus widely used in chemical synthesis. A pressing issue in modern organic chemistry, therefore, relates to the development of protocols that furnish access to these entities, particularly if readily available and previously unutilized starting materials can be employed. In a recent report in the Journal of the American Chemical Society, Professor James Morken and co-workers outline precisely one versatile instance of such a transformation. The newly developed strategy involves the alkoxide-promoted reaction of 1,1-bis(pinacolboronate) esters with alkyl halides by a pathway that results in the deletion of one of the two geminal boryl units, followed by C–C bond formation of the resulting boron-stabilized carbanion with an electrophile. The process can be accomplished easily on preparative scale (for example, >5 grams), is broadly applicable, and can be accomplished intramolecularly to furnish cyclic products. Mechanistic investigations through the use of 13C- and 10B-labeled compounds support the contention that transformations occur via boron-stabilized carbanions, likely stabilized by π-bonding between the carbanion and the remaining boron (B=C bonding). The research carried out in the Morken laboratories was funded by a grant from the National Institutes of Health.
To view the publication, see: http://pubs.acs.org/doi/abs/10.1021/ja505455z
Binding Affinity of p53: A Tumor Suppressor Peptide
The transcription factor p53 commences arrest of the natural cell cycle in response to DNA damage. The p53 peptide, like other short peptide segments of a protein, is found to be in disordered states in solution and therefore is not able to maintain proper interactions for binding. Stabilization of the 16-residue helical domain in p53 was previously accomplished by introducing an all-hydrocarbon tether of different lengths and stereochemistry. This stapled version of the p53 peptide was shown to slow the growth of cancer cells in vivo by activating the p53-mediated apoptotic paths.
Through modeling and binding affinity calculations, Professor Udayan Mohanty recently characterizes the effects of varying the peptide sequence and different parameters of the hydrocarbon bridge. The WaterMap method identified over one hundred hydration sites in the protein binding pocket and calculated the relative value of free energy released by displacing the hydration sites. The potentials of mean force obtained by the weighted histogram analysis method were calculated along a reaction coordinate for p53 binding to MDM2. He and his students found their binding affinity methods to be in agreement with experimental data and they correctly identify the order of the peptide variants from lowest to highest binding affinity. Their efforts are expected to help to further the development of a new generation of p53/MDM2 inhibitors that can reactivate the function of p53 as a tumor suppressor gene.
A Significant Advance in Chemical Synthesis: Sequential Catalytic and Enantioselective Formation of C–B and C–C Bonds
Terminal alkenes are among the most desirable starting materials in organic synthesis: they are manufactured on enormous scale and can be used in countless transformations. While their latent reactivity readily lends itself to hydrocarbon chain extension, alkenes have the attractive feature of being stable to many acids, bases, oxidants and reductants. Despite such attractive attributes, catalytic enantioselective transformations that utilize mono-substituted alkenes and proceed in high enantioselectivity (e.g., 95:5 enantiomer ratio or better) are scarce. In a recent publication in Nature, Professor James Morken along with senior graduate students Scott Mlynarski and Chris Schuster, outline a remarkable single-flask catalytic enantioselective process that transforms terminal alkenes into a range of useful and valuable products in high enantiomeric purity. The BC approach involves an all-catalytic sequence that includes a diboron addition and is followed by a regioselective cross-coupling to generate a C–C bond. A large assortment of otherwise difficult-to-access products can thus be generated in >95:5 enantiomer ratio by reactions that are promoted by no more than 1-2 mol % of commercially available catalysts and reagents.
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Surface Modification Increases Photovoltage Generation by "Rust" By Over 100%
Artificial photosynthesis seeks to harvest solar energy and directly convert it into chemical energy for easy storage and redistribution. In developing technologies to meet this goal, scientists face an important challenge that photoelectrodes often fail to generate enough voltage to power desired chemical reactions, such as the splitting of water into molecular oxygen and hydrogen. The challenge is probably best manifested by a prototypical material, hematite (α-Fe2O3), which can only produce 0.3 V power while its bandgap is >2 V. Professor Dunwei Wang and his team show that the issue can be mitigated by a simple surface modification. Using a recently identified oxygen evolution catalyst, the Wang group succeeded in measuring a photovoltage of 0.61 V (or an increase of 100%) on hematite. As a result, a record-low turn-on voltage of 0.62 V (vs. reversible hydrogen electrode) was observed. When combined with silicon nanowire dual absorbers, the turn-on potential was further reduced to 0.32 V (corresponding to a photovoltage of 0.91 V). These data, published in Angewendte Chemie International Edition, represent a new benchmark for the hematite-based solar water splitting reactions. Most significantly, the team considers the cause of the cathodic shift a result of improved thermodynamics, a dramatic deviation from previous views that such a shift would be a result of kinetic changes. The conclusion is supported by their photovoltage measurements under open circuit conditions where the influence of kinetic factors is nonexistent. The result renews the hope of using hematite, an earth abundant, inexpensive, and stable material, for practical artificial photosynthesis. This research was supported financially by the National Science Foundation and the Alfred P. Sloan Foundation.
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Enantioselective silyl protection of alcohols promoted by a combination of chiral and achiral Lewis basic catalysts
In Nature Chemistry, Professors Amir Hoveyda and Marc Snapper and their coworkers describe and demonstrate a counterintuitive strategy for dramatically accelerating the catalytic enantioselective monosilylations of diols and polyols to furnish valuable alcohol-containing molecules in high enantiomeric purity. In the past, such transformations typically required high catalyst loadings (20–30 mol%) and long reaction times (2–5 days). The team's new strategy involves the addition of an achiral co-catalyst that is structurally similar to the chiral catalyst, which effectively solves the problem. The key discovery is that a combination of seemingly competitive organic bases can function in concert, such that one serves as an achiral nucleophilic promoter while the other performs as a chiral Brønsted base. On the addition of 7.5–20 mol% of a commercially available N-heterocycle (5-ethylthiotetrazole), reactions typically proceed within one hour and deliver the desired products in high yields and high enantiomeric ratios. In some instances, there is no reaction at all in the absence of the achiral base, yet addition of the achiral co-catalyst gives rise to facile formation of products in high enantiomeric purity. The principles outlined in this paper serve as a conceptual framework for the development of new processes that demand separate and independently operational Lewis basic co-catalysts whose functions can easily overlap and the simultaneous use of which might initially appear to be detrimental towards achieving high enantioselectivity. This research was supported financially by the National Institutes of Health.
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A grossly warped nanographene and the consequences of multiple odd-membered ring defects
Graphite, the most stable form of elemental carbon, consists of pure carbon sheets stacked upon one another like reams of paper. Individual sheets, known as graphene, prefer planar geometries as a consequence of the hexagonal honeycomb-like arrangements of trigonal carbon atoms that comprise their two-dimensional networks. Defects in the form of non-hexagonal rings in such networks cause distortions away from planarity. In Nature Chemistry, Professor Lawrence T. Scott reported an extreme example of this phenomenon. A 26-ring C80H30 nanographene that incorporates five seven-membered rings and one five-membered ring embedded in a hexagonal lattice was synthesized by stepwise chemical methods, isolated, purified and fully characterized spectroscopically. Its grossly warped structure was revealed by single-crystal X-ray crystallography. An independent synthetic route to a freely soluble derivative of this new type of "nanocarbon" was also reported. Experimental data reveal how the properties of such a large graphene subunit are affected by multiple odd-membered-ring defects. This research was carried out in collaboration with Dr. Kenichiro Itami, Professor of Chemistry and Director of the Institute of Transformative Bio-Molecules at the University of Nagoya, Japan. The other authors of this paper include Dr. Yasutomo Segawa, an assistant professor at the University of Nagoya, Dr. Qianyan Zhang, a post-doctoral research fellow at Boston College, and Katsuaki Kawasumi, a Ph.D. student from Nagoya, who worked for three months during the course of this project as a visiting Ph.D. student at Boston College. The research was supported financially by the National Science Foundation and the Japan Society for the Promotion of Science.
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Readily Accessible and Easily Modifiable Ru-Based Catalysts for Efficient and Z-Selective Ring-Opening Metathesis Polymerization and Ring-Opening/Cross-Metathesis
In a recent publication in the Journal of the American Chemical Society, Professor Amir Hoveyda and his coworkers reported rationally designed Ru-based catalysts for efficient Z-selective olefin metathesis. The new complexes contain a dithiolate ligand and can be accessed in a single step from commercially available precursors in 68–82% yield. High efficiency and exceptional Z-selectivity (93:7 to >98:2 Z:E) were achieved in ring-opening metathesis polymerization (ROMP) and ring-opening/cross-metathesis (ROCM) processes; the transformations typically proceed at 22 °C and are operationally simple to perform. Complete conversion was observed with catalyst loadings as low as 0.002 mol %, and turnover numbers of up to 43 000 were achieved without rigorous substrate purification or deoxygenation protocols. X-ray data and density functional theory computations provide support for key design features and shed light on mechanistic attributes. This research was supported financially by the National Science Foundation, a LaMattina Graduate Fellowship to Mr. R. Kashif M. Khan, and a Swiss NSF Postdoctoral Fellowship to Dr. Sebastian Torker.
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1,3,5-Triazine as a Modular Scaffold for Covalent Inhibitors with Streamlined Target Identification
Cysteine residues play key functional roles in regulating protein activity by acting as catalytic nucleophiles, sites of metal-binding, and redox-active centers. Small molecules that covalently modify these functional cysteine residues provide pharmacological tools to perturb protein activity within biological systems. In a recent publication in the Journal of the American Chemical Society, Professor Eranthie Weerapana and her coworkers reported the utility of trifunctionalized 1,3,5-triazine as an ideal modular scaffold to generate covalent inhibitors for cysteine-mediated protein activities. Triazines were derivatized with a thiol-reactive electrophile for covalent modification of target proteins, an alkyne as a click-chemistry handle for target identification, and a binding group to direct the compounds toward distinct subsets of the proteome. A library of trifunctionalized triazines was generated, and the cellular protein targets for these compounds were evaluated. These cellular screens identified two compounds, RB-2-cb and RB-11-ca, as cell permeable and highly selective covalent modifiers for Cys239 of beta-tubulin (TUBB) and Cys53 of protein disulfide isomerase (PDI), respectively. These compounds demonstrate in vitro and cellular potencies that are comparable to currently available modulators of tubulin polymerization and PDI activity. These findings demonstrate the versatility of the triazine core as a modular scaffold to generate potent and selective covalent modifiers of diverse protein families for future chemical genetics applications. Future studies will apply these bioactive small molecules to further interrogate the role of TUBB and PDI in a variety of pathological systems and expand the triazine library to target other reactive amino acids in the proteome. Postdoctoral fellow Ranjan Banerjee, graduate student Nicholas Pace, and undergraduate student Douglas Brown contributed to this study.
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Simple Organic Molecules as Catalysts for Enantioselective Synthesis of Amines and Alcohols
Discovery of easily accessible catalysts that generate high value organic compounds by sustainable enantioselective transformations is central to advances in the life sciences. In the February 14 issue of Nature, in a paper by various members of the Hoveyda research group, graduate students Dan Silverio and Erika Vieira, postdoctoral fellows Drs. Sebastian Torker and Tanya Pilyugina, and senior research associate Dr. Fredrik Haeffner introduce a set of small organic molecules that catalyze reactions of unsaturated organoboron reagents with imines and carbonyls; products are amines and alcohols of high enantiomeric purity, intermediates used to synthesize many biologically active molecules. A distinguishing feature of the catalyst class is a proton embedded within their structure. The resulting electronic activation and structural organization play a key role in every stage of the carbon-carbon bond forming processes; this includes achieving high rates of catalyst regeneration and product release, typically obtained through rapid ligand exchange with metal-containing systems. The catalyst is derived from the abundant amino acid valine and can be prepared in large quantities in four steps with cheap chemicals. Reactions are scalable, do not demand stringent conditions, can be performed with as little as 0.25 mole % catalyst in less than six hours at room temperature, and furnish products typically in >85% yield and ≥97:3 enantiomeric ratio. The efficiency, selectivity and operational simplicity of the transformations and the range of compatible boron-based reagents render this advance vital to future progress in chemistry, biology and medicine. The research is part of a longstanding collaboration (since 1995) between the research groups of Professor Amir Hoveyda and Professor Marc Snapper in our department.
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Selectivity Control of Heterogeneous Catalysis: Designing Selective Reaction Pores on Metal Surfaces
Metal nanoparticle heterogeneous catalysts are used in most of the industrial chemical processes because they are easy to handle, separate, recover, and reuse. Unfortunately, it is much more challenging to control the selectivity and activity of heterogeneous catalysts compared to homogeneous catalysts. To tackle this challenge, Assistant Professor Frank Tsung and his students have developed a new concept to control heterogeneous catalysis by coating the catalyst with a layer of nanoporous shell. The pores in this skin-like shell modulate the reactions, just like the active packets in enzymes regulate biochemical reactions.
A heterogeneous catalytic process typically involves three important steps: the adsorption of reactant molecules on the active metal surface, reaction between reactant molecules on the metal surface, and, finally, desorption of products. In Prof. Tsung's design, a nanoporous material, a metal organic framework (MOF), is coated on the surface of metal nanoparticles. Because the size of the MOF pores is comparable to that of the reactant molecules, the MOF could concurrently manipulate the molecular size-selectivity, adsorption geometries and sorption energies of reactant molecules on the catalyst surface. The Tsung group has applied this catalyst to the gas-phase hydrogenation of ethylene, cyclohexene, and cyclooctene. The size of ethylene is smaller than the pore size of the MOF; the size of cyclohexene is similar to the pore size, and the size of cyclooctene is much bigger than the pore size. The MOF shell provides excellent molecular-size selectivity. The results show high activity in ethylene and cyclohexene hydrogenations but not in cyclooctene hydrogenation. Different activities for cyclohexene hydrogenation were obtained for the catalysts with and without the MOF shell. The difference could be due to the conformation of the molecules on the metal surface during the hydrogenation. The cyclohexene molecules could only interact with the active metal surface by the successive variation in their conformations. None of these enzyme-like behaviors have ever been previously observed in heterogeneous catalysis. The work has been published in J. Am. Chem. Soc. 2012, 134, 14345-14348.
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Magnesium Fluctuations Modulate RNA Dynamics in the Sam-I Riboswitch
Experiments demonstrate that Mg2+ is crucial for structure and function of RNA systems, yet the detailed molecular mechanism of Mg2+ action on RNA is not well understood. In collaboration with the research groups of Jose Onuchic (UCSD/Rice) and Karissa Sanbonmatsu (Los Alamos), Professor Udayan Mohanty has examined the interactions between RNA and its ion atmosphere at atomic resolution in the SAM-I aptamer. Specifically, they have carried out ten 2 µs explicit solvent molecular dynamics simulations and determined the excess number of ions around RNA as a function of varying ion concentrations. This quantity, which is experimentally measurable, is called the preferential interaction coefficient. Surprisingly, the investigators found that between 80% and 85% of the excess Mg2+ ions that contribute to the preferential interaction coefficient reside in the outer-sphere layer. The electronegative RNA atoms and the hydration layers both play a role in situating the excess Mg2+ ions. Furthermore, the outer-sphere Mg2+ ions exhibit 100-fold slower kinetics than the Mg2+ ions in the diffuse layer. As the outer-sphere accounts for most of Mg2+, it changes the paradigm of the characteristics of RNA-Mg2+ interactions. The work has been published in J. Am. Chem. Soc. 2012, 134, 12043–12053.
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Transitions from Functionalization to Fragmentation Reactions of Secondary Organic Aerosol (SOA) Generated from OH Oxidation of Alkaline Precursors
The importance of atmospheric aerosols as climate forcing agents has become evident. The quantitative parameters required for reliable modeling aerosol climate effects, however, are not yet available. This is most notably the case for organic aerosol. To address this problem, Professor Paul Davidovits and his collaborators have been systematically studying the formation of organic aerosol via atmospheric oxidation of organic vapors due to anthropogenic and biogenic emissions. They measure cloud formation effectiveness and optical properties of organic aerosols of known shape, size, and composition. They also determine how these properties are affected by transformations in the atmosphere via oxidative reactions and coatings formed by deposition.
The experiments described in their publication in Environmental Science & Technology 2012, 46, 5430 were designed to study aerosol formation from gas phase alkanes emitted into the atmosphere as a result of oil spills such as the Deepwater Horizon accident. The experiments provided data that determine yields and chemical composition of the aerosol produced from atmospheric oxidation of the relevant gas phase species.
These studies were conducted in Professor Davidovits's laboratories at Boston College in collaboration with colleagues from Aerodyne Research Inc., MIT, and Pennsylvania State University. The wide range of instruments and expertise required to perform complex atmospherically relevant studies make such collaborations essential. Three Boston College undergraduate students, David R. Croasdale, Justin P. Wright, and Alexander T. Martin, were important participants in these experiments and are co-authors of the publication.
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Efficient Syntheses of 6,5'-(S)- and 6,5'-(R)- Cyclouridine
Professor Larry W. McLaughlin and graduate student Christopher S. Theile have successfully synthesized both the 5'-R and the 5'-S diastereomers of 6,5'-cyclouridine. Cyclonucleosides feature an extra bond between the backbone/sugar portion of the nucleoside and the base. These compounds are products formed in vivo from oxidative damage induced from radiation exposure or reactive oxygen species. The work has been published in Chem. Commun. 2012, 48, 5587.
Two diastereomers can be formed in the cyclization reaction. The 5'-S isomer has its 5' hydroxyl group positioned over the sugar portion of the nucleoside, whereas the 5'-R compound has its hydroxyl group pointed away. These compounds have been very difficult to synthesize, especially the 5'-R isomer. The McLaughlin lab synthesis features an efficient oxidation step that generates both isomers at once, but favors the 5'-R compound over the 5'-S in a nearly 2:1 ratio. X-ray crystal structures of the compounds were also obtained, which show that the nucleobase is "pulled" back from its normal position, preventing it from forming hydrogen bonds in its native fashion.
Now that these compounds have finally been synthesized in the laboratory in an efficient manner, other scientists can begin using them to probe enzymes and biological systems, in order to understand better the damage that these cyclonucleosides can cause.
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Dual Absorber Hematite/Si Nanowire System for Photoelectrochemical Water Splitting at Low Applied Potentials
Using the sun to split water into oxygen and hydrogen, which could be used for fuel, remains elusive. However, a new study by Associate Professor Dunwei Wang and co-workers brings this goal tantalizingly closer by crafting silicon nanowires coated with hematite (alpha-Fe2O3) that work synergistically to collect photons from different areas of the solar spectrum for conversion into electricity.
Such sun-powered water splitting, also known as photoelectrochemical (PEC) water splitting, would be an efficient way to collect solar energy and use it in the form of hydrogen fuel. The choice of the photoelectrode, the component that collects solar energy and converts it into electricity, is especially important because it determines the water-splitting device's performance over time. The ideal photoelectrode would absorb light broadly, be inexpensive, and resist photocorrosion. Hematite fits some of these characteristics, but alone, it doesn't perform well enough for consideration.
To improve hematite's performance, Professor Wang's research team grew crystals of this iron oxide on silicon nanowires, a material that absorbs light that is transparent to hematite. Together, the two materials absorb light from a much larger portion of the solar spectrum and efficiently convert that energy into electricity. The fact that the photoelectrode's active materials are "primarily composed of three of the four most abundant elements in Earth's crust (O, Si, and Fe) offers promise that renewable energy harvesting by PEC water splitting remains an achievable goal", Professor Wang concludes.
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Silicon Nanowires as Photoelectrodes for Carbon Dioxide Fixation
Natural photosynthesis harvests solar energy and stores it in chemical bonds. The synthesis typically proceeds in two steps, a light reaction that splits water to produce dioxygen molecules, followed by dark reactions that fix carbon dioxide and yield organic compounds with high yield and specificity. In an effort to develop technologies that can meet our ever-increasing energy demand in a renewable fashion, scientists and engineers have researched heavily to understand and mimic these reactions. To date, the focus has been mainly on how to harvest solar energy efficiently; however, the other aspect of using the energy converted from photons to produce synthetically valuable molecules is a far more challenging problem. An important reason for the challenge is the rich oxidation states of carbon, from -4 (e.g., in CH4) to +4 (in CO2), and the fact that the energy difference between reactions that would produce carbon with various oxidation states is typically too small to allow for high selectivity.
Using a photoelectrode made of Si nanowires and employing ketones as electron-receiving substrates, Assistant Professors Wang and Tan teamed up to demonstrate a proof-of-concept that may provide a solution to the challenge. In close similarity to natural photosynthesis, their strategy seeks to carry out the reactions in two steps. First, light strikes Si nanowires to excite electrons, which transfer to ketones such as benzophenone to produce radical anions. Then, the radical anions react with carbon dioxide in a highly specific manner (see Figure above). After a second electron transfer from the Si nanowire photoelectrode, the carbon fixation process is complete to produce carboxylic acids. The advantages of this strategy include high energy conversion efficiency, durability of the photoelectrode, a cheap carbon source, as it is from carbon dioxide, high chemical yields, and high specificities of the reactions, the last which of is demonstrated in the synthesis of precursors for ibuprofen and naproxen.
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The First Book about Geodesic Polyarenes, Carbon Nanorings, and Aromatic Hydrocarbon Belts
The book Fragments of Fullerenes and Carbon Nanotubes: Designed Synthesis, Unusual Reactions, and Coordination Chemistry grew out of a very successful symposium on the same topic that was held in conjunction with the 2008 national meeting of the American Chemical Society in Philadelphia. Shortly after that meeting, an editor from John Wiley & Sons approached Professor Lawrence T. Scott and Professor Marina Petrukina from the University at Albany, who had coorganized the symposium, about publishing a book on this burgeoning branch of chemistry. The two agreed to accept the challenge, and each contributed a chapter to the book from their own research. The other chapters in this edited monograph were written by prominent experts in the field from all over the world, many of whom had spoken in the symposium. The chapter written by Professor Scott on "Hemispherical Geodesic Polyarenes: Attractive Templates for the Chemical Synthesis of Uniform Diameter Armchair Nanotubes" reports previously unpublished results from the Ph.D. thesis of former BC graduate student Anthony Belanger, as well as contributions from the undergraduate research of former BC chemistry major and Scholar of the College Katherine Mirica and early groundwork by former postdoctoral fellow Dr. James Mack. The front cover of the book is adapted from "La Tricoteuse," a painting by William Adolphe Bouguereau (1825-1905), digitally modifed to show the girl knitting a scarf in the likeness of a carbon nanotube.
For a video interview with Professor Scott about this book, go to:
For more details and a list of chapters, go to:
The First Chemical Synthesis of a Short, Rigid, Structurally Pure Carbon Nanotube
The discovery of carbon nanotubes in 1991 almost instantly inspired dreams among scientists and engineers about how these light weight, super strong, heat resistant, ultra thin nanowires could someday be used to miniaturize electronic devices down to the nanometer scale, well beyond the limits of what can ever be achieved by lithography on silicon chips. Unfortunately, not all carbon nanotubes (CNTs) are alike. Some are semiconductors, whereas others are highly conductive, like metals, with current carrying capacities up to 1000 times greater than that of copper wire. Despite two decades of extensive experimentation worldwide, however, all known preparation methods still yield mixtures of different types of CNTs that are virtually impossible to separate into their individual components in useful amounts. Stimulated by the challenge to address this long-standing problem, Professor Lawrence Scott and his students began exploring a revolutionary new production strategy involving the controlled elongation of small hydrocarbon templates, such as hemispherical nanotube end-caps, prepared by bottom-up chemical synthesis; the diameter and rim structure encoded in the template would dictate the diameter and chirality of the resulting CNT. Toward that objective, the Scott laboratory has succeeded in synthesizing a short CNT by chemical methods in just three steps from corannulene, a readily available starting material. The new C50H10 geodesic polyarene has been isolated, purified, crystallized, and fully characterized by NMR spectroscopy, UV-vis absorption spectroscopy, high resolution mass spectrometry, and X-ray crystallography. With this advance, a major obstacle to the rational synthesis of structurally uniform CNTs has been overcome. Only now that a small hydrocarbon template such as this is finally available can methods for elongating it into uniform CNTs be tested or invented. Work on this final phase is currently in progress. Financial support was provided by the National Science Foundation and the Department of Energy.
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To read other accounts of this work, go to:
A Practical and Catalytic Method that Provides Access to Many Biologically Active Molecules
A large number of biologically active macrocycles contain a C–C double bond through which various other derivatives are prepared; the stereochemical identity of the alkene or the resulting moieties can be critical to the beneficial properties of such molecules. Catalytic ring-closing metathesis (RCM) is a widely employed method for the synthesis of large unsaturated rings; however, cyclizations often proceed without control of alkene stereochemistry. Such shortcoming is particularly costly with complex molecules when cyclization is performed after a long sequence of transformations. In the most recent issue of Nature (2011, 479, 88–93; doi:10.1038/nature10563), Professor Amir Hoveyda, graduate student Miao Yu and postdoctoral fellow Chenbo Wang disclose a practical and general approach for efficient and highly stereoselective synthesis of macrocyclic alkenes by catalytic RCM; transformations deliver up to 97% Z selectivity due to control induced by a tungsten-based alkylidene. The exceptional utility of the method is demonstrated by stereoselective preparation of highly potent anti-cancer agents epothilone C and nakadomarin A, previously reported syntheses of which have been marred by late-stage non-selective RCM. The team reports that the tungsten alkylidene can be manipulated in air, promoting reactions carried out in a fume hood to deliver products in useful yields and high Z selectivity. As a result of efficient RCM and re-incorporation of side products into the catalytic cycle with minimal alkene isomerization, desired cyclizations proceed in preference to alternative pathways even under relatively high concentration (0.1 molar). The research, conceived and largely performed in the Boston College laboratories by Wang and Yu, is in collaboration with Professors Richard Schrock (MIT) as well as Professor Darren Dixon (Oxford) and two members of his team. Financial support was provided by the National Institutes of Health and the UK ESPRC.
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Novel Imaging Agents of Cell Death
Essentially all anticancer drugs work by directly or indirectly inducing apoptosis of cancer cells, the programmed cell death pathway. Therefore, noninvasive imaging of apoptotic cells should enable prompt evaluation of the efficacy of cancer therapeutics. In principle, apoptotic cell death can be reliably detected by targeting the lipid molecule phosphatidylserine (PS), which in healthy cells is completely confined to the cytosolic side of the plasma membrane. In apoptosis, the distribution asymmetry is lost, resulting in PS exposure on the surfaces of dying cells. Natural PS-binding proteins are less than ideal as imaging agents of apoptosis for multiple reasons, including their large size, low stability, difficulty of labeling, and their poor tissue penetration. Small molecule ligands that specifically target PS may circumvent these problems and thereby serve as powerful imaging tools for cancer research and treatment. In their recent paper in the Journal of the American Chemical Society, Professor Jianmin Gao and coworkers report a new class of PS-targeting molecules that enables facile imaging of apoptotic cells. These PS-imaging agents are developed by using a biomimetic approach: the PS-binding epitope of the milk protein lactadherin are grafted onto a cyclic peptide scaffold; rational optimization using unnatural amino acids results in the cyclic lactadherin mimics (cLacs) that preferentially associate with PS-presenting membranes. The cLac design also benefits from the intrinsic membrane impermeability of peptides, which allows cLacs to target surface-exposed PS. A fluorophore labeled cLac effectively detects apoptotic cells under a fluorescence microscope. Given the small size and ease of synthesis and labeling, cLacs hold great promise for noninvasive imaging of cell death in living animals and ultimately in patients.
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Kantrowitz Lab uses X-ray Crystallography to Provide a Molecular Level Description of Each of the Steps in the Catalytic Cycle of a Critical Metabolic Enzyme
Graduate students Katharine Harris and Gregory Cockrell, along with undergraduate David Puleo, working with Professor Evan Kantrowitz have used protein crystallography and theoretical studies to provide a detailed mechanism of the reaction catalyzed by the enzyme aspartate transcarbamoylase. This enzyme catalyzes one of the first reactions in the biosynthesis of the pyrimidine nucleotides, the building blocks of DNA and RNA. This enzyme also helps to control the rate of the entire pathway and has become the target for the development of drugs that can be used to fight cancer and malaria. This work is important because it provides details on the molecular level of the active site of the enzyme and the steps involved in the catalytic reaction, which are critical for drug design. By combining data from three high-resolution X-ray crystal structures of the enzyme in the absence of ligands, in the presence of one of the enzyme's two substrates, and in the presence of the bisubstrate/transition state analog with theoretical studies involving in silico docking and electrostatic calculations, the Kantrowitz Lab has been able to visualize each step in the catalytic cycle of ATCase, from the ordered binding of the substrates, to the formation and decomposition of the tetrahedral intermediate, to the ordered release of the products from the active site. These results provide a molecular level portrait of how this critical metabolic enzyme functions.
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Tan Lab Extends Its Scaffolding Catalysis Strategy To a Metal-free System for the Enantioselective Desymmetrization of 1,2-Diols
Students working with Professor Kian Tan have recently developed a new non-metal catalyst that uses reversible covalent bonding between catalyst and substrate in order to enhance both reactivity and selectivity. Graduate students Xixi Sun and Amanda Worthy disclosed in Angew. Chem., Int. Ed. that these scaffolding catalysts are highly effective for the enantioselective desymmetrization of 1,2-diols. For most synthetic catalysts, reversible covalent bonding is used to form a reactive intermediate, thereby affording enhanced rate of reaction. In this case reversible covalent bonding is implemented to transiently tether reagents. A key aspect of this mode of catalysis is that a part of the acceleration arises from the entropic advantage gained through intramolecularity. This mode of catalysis is infrequently used in synthetic catalyst designs but holds great promise as a general method for accelerating reactions.
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Snapper Lab Builds Polycyclic Lactones by Powerful Tandem Catalytic Reaction Sequences
David F. Finnegan, working in Professor Marc L. Snapper's laboratory developed a new ruthenium-catalyzed tandem reaction sequence that generates polycyclic compounds from acyclic precursors in one reaction flask. The process uses a single ruthenium additive to catalyze the two mechanistically distinct transformations; a ring closing metathesis followed by a hetero-Pauson-Khand cycloaddition. The key to developing this tandem process was to learn how to convert in situ the metathesis active ruthenium alkylidene into a hetero-Pauson-Khand cycloaddition catalyst. This was accomplished by treating the metathesis active ruthenium complex with CO to remove the alkylidene functionality, followed by a reductant (methoxide) and more CO to generate the active ruthenium (0) carbonyl complex that catalyzes the desired cycloaddition. This work was published as a "Feature Article" in the Journal of Organic Chemistry. The National Science Foundation provided financial support for these studies.
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A Boron-Based Synthesis of the Natural Product (+)-trans-Dihydrolycoricidine
A synthesis of the natural product trans-dihydrolycoricidine has been accomplished through the aid of new boron-based chemical reactions developed in the laboratory of Professor James Morken. Postdoctoral fellow Dr. Sarah Poe (now at the Warner-Babcock Institute for Green Chemistry) developed a diastereoselective diboration reaction that converts cyclic dienes to single isomer cyclohexendiols (Eq. 1, above). This reaction occurs with excellent levels of stereoselectivity and can accomplish oxidations that have not been possible with singlet oxygen-based methods. Dr. Poe then employed this reaction along with catalytic allylboration reactions that the Morken group has also developed to provide an efficient synthesis of the target molecule. The work has been published in Angewandte Chemie.
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Enantioselective Conjugate Addition of SiMe2Ph Catalyzed by a Chiral N-Heterocyclic Carbene
Research in the laboratory of Professor Amir Hoveyda has resulted in the development of the first catalytic method for forming carbon–silicon bonds that does not require an organometallic complex as the catalyst. This accomplishment is based on a discovery made two years ago in the Hoveyda group, illustrating that achiral N-heterocyclic carbenes (NHCs) – in the absence of a metal salt – can activate a B–B bond to catalyze efficient, but non-enantioselective, boronate conjugate additions to α,β-unsaturated carbonyl compounds. In a recent communication in the Journal of the American Chemical Society, Hoveyda and graduate student Jamie O'Brien disclose a metal-free method for enantioselective conjugate addition of the versatile dimethylphenylsilyl group to a wide variety of α,β-unsaturated carbonyl compounds. Transformations are catalyzed by a chiral N-heterocyclic carbene (NHC) and are performed in an aqueous solution, which makes them operationally simpler to perform than the NHC–Cu-catalyzed variant. The chiral catalyst, also originally developed in the Hoveyda group, is generated from a readily accessible enantiomerically pure imidazolinium salt (prepared in three steps) and a common organic amine base. NHC-catalyzed processes proceed with 5.0-12.5 mol % catalyst loading at room temperature within 1-12 hours, affording the desired products in up to >98:2 enantiomeric ratio and in up to >98% yield. Cyclic enones or lactones and acyclic α,β-unsaturated ketones, esters as well as aldehydes can be used as substrates.
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Catalytic Z-Selective Olefin Cross-Metathesis for Natural Product Synthesis
Alkenes are found in a great number of biologically active molecules and are employed in numerous transformations in organic chemistry. Many olefins exist as E or higher energy Z isomers. Catalytic procedures for the stereoselective formation of alkenes are therefore valuable; nonetheless, methods for synthesizing 1,2-disubstituted Z olefins remain scarce. In an Article published in Nature, Professor Amir Hoveyda and his team report catalytic Z-selective cross-metathesis reactions of terminal enol ethers, which have not been reported previously, and allylic amides, which have been employed until now only in E-selective processes; the resulting disubstituted alkenes are formed in up to >98% Z selectivity and 97% yield. The new transformations are promoted by catalysts that contain the highly abundant and inexpensive molybdenum, and are amenable to gram-scale operations. The Article introduces the use of reduced pressure as a simple and effective strategy for achieving high stereoselectivity. The utility of the new discovery was demonstrated by syntheses of anti-oxidant C18 (plasm)-16:0 (PC), found in electrically active tissues and implicated in Alzheimer's disease, and the potent immunostimulant KRN7000. The research was performed by postdoctoral fellow Dr. Simon J. Meek, graduate student Robert V. O'Brien, and visiting scholar Josep Llaveria, from Spain, as part of the longstanding collaboration with Professor Richard Schrock at MIT. Funding was provided by the NIH (joint grant to Hoveyda and Schrock) as well as an NSF grant to Hoveyda; O'Brien is a LaMattina graduate fellow, and Llaveria was funded by the Spanish Ministry of Education.
For more details, see also:
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Nature's Clever Use of Thermal Fluctuations
Recent research published in the Proceedings of the National Academy of Sciences by Professor Udayan Mohanty has advanced our understanding of the clever ways the molecular machinery of life uses fluctuations and dissipation and the large role that thermal fluctuations between structures plays in enzymatic function.
With the advent of single molecule methods, scientists have begun to get a glimpse into how nature has developed its molecular machinery not only to deal with fluctuations, but even to use them to advantage. Single molecule experiments indicate that large and rare thermal fluctuations of the ribosome are essential to rotate the ternary complex into a position so as to facilitate stable contacts with the GTPase activated center (GAC) and the sarcin-ricin loop (SRC) in the large subunit.
In collaboration with Professor Steven Chu at U.C. Berkeley, Professor Mohanty and his students have explored how large, rare thermal fluctuations of the ribosome aid in the functioning of the ribosome. Their theoretical findings establish that configurations, which make significant contribution to the probability of the rare process, have the inherent property that they are localized tightly around the most likely configuration. Small variations in the re-positioning of cognate relative to near-cognate complexes lead to significant rate enhancement.
The protein functional groups, the structural positioning of the RNA, and the inner-sphere coordination of the protein atoms to them, create several unique motifs for the binding of Mg2+ ions in the large subunit of H. marismortuni and E. coli ribosomes. The paper examines over a dozen unique structural motifs of magnesium binding sites to further elucidate the interplay between structure, dynamics and function within the ribosome and to provide insights into how site-bound magnesium ions contribute to its structural stability.
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Zinc(II)-Catalysis of Keteniminium Ion Formation Enables a New Approach to Four-Membered Rings
The Ghosez synthesis of cyclobutanones based on keteniminium salts is a useful variant of the classic ketene–olefin [2+2] cycloaddition reaction. Each process generates four-carbon ring strain and formally accomplishes the vicinal carbofunctionalization of an alkene. Professor Jason Kingsbury and graduate student Jamie O'Brien have now published a full article in The Journal of Organic Chemistry that describes, for the first time, catalysis of keteniminium–alkene cyclocondensation. The new transformations take place with complete regiochemical control at room temperature in the absence of solvent, giving functional cycloadducts with hindered all-carbon-substituted stereocenters. Their studies also include the results of extensive ab initio calculations carried out in collaboration with recent graduate Dr. Adil Zhugralin to help elucidate the reaction mechanism. The authors hope that their work can inspire modern enantioselective entries to substituted cyclobutanones, since prior strategies have relied exclusively on pyrrolidine-based chiral auxiliaries.
To read the article, go to:
Professor Kian Tan's synthesis of beta-amino-aldehydes
The synthesis of beta-amino-aldehydes has been achieved through enantioselective hydroformylation of PMP-protected allylic amines. The reaction is accomplished by using a scalemic scaffolding ligand that covalently and reversibly binds to the substrate. These ligands behave like chiral auxiliaries because they are covalently attached to the substrate during hydroformylation; however, similar to traditional asymmetric ligands, they can be used in catalytic quantities. The directed hydroformylation of disubstituted olefins occurs under mild conditions (35 °C and 50 psi CO/H2), and Z-olefins afford excellent enantioselectivities (up to 93% ee).
To read the article, go to: http://pubs.acs.org/doi/abs/10.1021/ja107433h
To read a published commentary on the article, go to: http://onlinelibrary.wiley.com/doi/10.1002/anie.201006489/abstract
Professor Lawrence Scott's article highlighted on the cover of Journal of Materials Chemistry
Carbon nanotubes have been widely touted for their potential to fulfill dreams in materials science and nanotechnology. Despite intense scrutiny by scientists and engineers worldwide for two decades, however, these fascinating carbon-rich materials are still being made today by poorly understood empirical methods that produce inseparable mixtures of tubes, the properties of which vary widely as a function of tube diameter and chirality. This inhomogeneity has seriously impeded realization of numerous applications envisioned in molecular scale electronics that require single-walled nanotubes (SWNTs) with uniform properties. Only those tubes that exhibit metallic properties can serve as electrically conductive nanowires, for example.
Professor Scott and graduate student Eric H. Fort have recently demonstrated that nitroethylene can serve as a highly reactive "masked acetylene" for converting aromatic hydrocarbon bay regions into new, unsubstituted benzene rings by a one-pot Diels-Alder cycloaddition/rearomatization reaction sequence, and this new methodology holds great promise as a strategy for the metal-free growth of single-diameter, single-chirality carbon nanotubes from small hydrocarbon templates (see doi/pdf/10.1021/ja907802g and doi/10.1002/anie.201002859/pdf). In their recently highlighted J. Mater. Chem. article, Fort and Scott report molecular orbital calculations on the Diels–Alder reactivity of aromatic belts and hemispherical end-caps of varying dimensions, and their results offer strong support for the feasibility of this strategy. Bay regions on the rim of a [10,10]nanotube end-cap are predicted to exhibit Diels–Alder reactivity comparable to that of bay regions in planar polyarenes that have already been successfully transformed into new benzene rings by nitroethylene. Some hurdles still remain, but the day is drawing nearer when SWNTs of predefined diameter and chirality will be "made to order" by chemical methods in the laboratory.
To read the article, go to:
Atmospheric Research at Boston College
Discovery and development of catalytic methods for enantioselective conjugate additions of easily accessible C-based nucleophiles to unsaturated carbonyls faciliates the synthesis of a large assortment of enantiomerically enriched biologically active molecules and are therefore of great significance. Nevertheless, notable shortcomings persist in this area, particularly in the context of reactions furnishing quaternary carbon stereogenic centers. One deficiency relates to the paucity of protocols for catalytic conjugate additions of vinyl groups. Recent research in the Hoveyda group, reported in a recent Communication in the Journal of the American Chemical Society and performed by graduate students Tricia L. May and Jennifer A. Dabrowski, puts forward an exciting new method for enantioselective conjugate addition of silyl-substituted vinylaluminum reagents to five- and six-membered b-substituted cyclic ketones. Reactions are catalyzed by a chiral bidentate N-heterocyclic carbene-copper catalysts, originally designed and developed in the Hoveyda laboratories and used for a wide range of other important transformations such as enantioselective olefin metathesis, allylic substitutions, hydroboration and diboration reactions. The new catalyst is derived from air stable and commercially available CuCl2•2H2O, affording the desired products in up to 95% yield and >98:2 enantiomeric ratio. The resulting enantiomerically enriched vinylsilanes can be protodesilylated, converted to the corresponding vinyl halides, or oxidized to b-acyl-substituted enones in high efficiency. The utility of the NHC–Cu-catalyzed reaction has been demonstrated through a concise enantioselective total synthesis of natural product riccardiphenol B.
To read the article, go to:
New Water Splitting Electrodes Developed
One key challenge in materials research is how to tailor certain aspects of the intrinsic properties of a material without adversely altering others. This problem has made it extremely difficult to progress at a meaningful pace in several critical fields, such as efficient energy storage and high-capacity energy storage. In a recent study, Assistant Professor Dunwei Wang, demonstrates that this challenge can be addressed, at least in part, by forming heteronanostructures. Differing from simple nanostructures, heteronanostructures consist of multiple parts, each of which may be selected or tailored independently. When combined, they contribute to offering a collection of property features that are not found in simple nanostructures, thus making high-efficiency solar water splitting possible. An important step to this goal is recently reported in Angew. Chem. Int. Ed. (doi: 10.1002/anie.201004801), in which the Wang group achieved WO3-based photoelectrodes that are stable in neutral solutions (pH 7) and exhibit high catalytic activities. The discovery was enabled by the introduction of two material components – a TiSi2 nanonets for effective charge transport and an oxygen evolving catalyst (provided by their collaborator, Assistant Professor Harvey Hou, at the University of Massachusetts at Dartmouth) for fast charge transfer. Building on this success, the Wang group is presently applying similar design concepts to construct electrodes that will permit practical water splitting as a form of energy harvesting and storage.
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The total synthesis of sclerophytin A by the Morken Group
The oxygenated cembrane diterpenes are a large class of natural products comprising cladiellins, briarellins, asbestinins, and sarcodictyins. Their intricate chemical structures have captivated many in the synthetic chemistry community. In addition to intriguing structures, these compounds also tend to possess potent biological activity. Amongst the cladiellins, sclerophytin A is a particularly striking compound; it was isolated from the marine soft coral Sclerophytum capitalis and found to exhibit remarkable potency against mouse leukemia cells (cytotoxic at 1 ng/ml versus L1210 cell line), yet its original structural formulation was incorrect. Total syntheses by the Paquette and Overman groups established the correct formulation of sclerophytin A to be that depicted in Scheme 1. As a means to examine the utility of the stereoselective Oshima-Utimoto reaction in chemical synthesis, Professor James Morken's research group has been attracted to the target sclerophytin A and its structural relatives. In this study, we show that (-)-sclerophytin A can be constructed in 13 steps from geranial. Highlights from the synthesis are a stereoselective Oshima-Utimoto reaction, a Shibata-Baba indium-promoted radical cyclization, and a novel stereoconvergent epoxide hydrolysis.
To read the article, go to:
This work was highlighted in Nature Chemistry. See: http://www.nature.com/nchem/reshigh/2010/1110/full/nchem.927.html
Professor Larry McLaughlin's research featured in Chemical & Engineering News
To control the expression products from unwanted genes including those from oncogenes, transformed cells and viral infections, it would be very valuable to target and inhibit the process of RNA transcription. Gene-specific pharmaceuticals would result. This process begins with the ability to recognize specific double-stranded DNA sequences. The natural processes for such recognition and control relies typically with proteins (suppressors and repressors) binding to DNA and selectively preventing transcription. Our understanding of the recognition processes between proteins and specific DNA sequences is not sufficient to design and prepare a protein product to target a unique double-stranded sequence.
The use of a single strand of DNA to target duplexes is feasible, but to date the one residue to one base pair format (resulting in DNA triplexes) has been limited to polypurine sequences; targets that are not biologically very prevalent, particularly in the DNA sequences of interest. We are developing a fundamentally new type of recognition format in which a third strand of DNA (or the related peptide nucleic acid, PNA) inserts itself between two Watson-Crick faces of the base pairs of the target duplex. The resulting Janus-Wedge (J-W) triplex (Janus after the Roman god often depicted with two faces) can be generalized to any duplex target. The success of this project will lead to a new generation of gene-specific pharmaceuticals.
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The Gao Group Publishes a VIP in Angewante Chemie
The latest research of the Gao group, appearing as a VIP article in Angewante Chemie, has ushered a new modality of molecular recognition into protein design. VIP (Very Important Paper) designation in Angewante Chemie represents the highest recommendation that a manuscript may receive in peer review. According to the journal, less than 5% of their manuscripts receive this distinction.
Well-programmed assembly of biomolecules serves as the foundation of the complex and hierarchical organization of biology. The exquisite specificity of molecular assembly is driven by a collection of noncovalent forces, including the well-characterized hydrogen bonding and electrostatic interactions. The report by Professor Jianmin Gao and his student Hong Zheng demonstrates for the first time that the quadrupolar interaction between aromatic rings can be utilized to program the specific assembly of protein molecules.
Aromatic compounds – benzene, for example – display an electronegative center and electropositive edge. This uneven electron distribution gives zero dipole, yet a big quadrupole moment. Perfluorinated benzene exhibits an opposite quadrupole and tends to bind benzene in a face-to-face geometry. To evaluate the potential of this unique noncovalent interaction in protein design, Gao and Zheng replaced all four aromatic residues in the core of a homodimeric protein with the perfluorinated variants. Structured as a homodimer on its own, the fluorinated mutant disrupts the native dimeric fold of the wild type protein to form heterodimers exclusively. The homodimer to heterodimer conversion is attributed to the cross affinity of aromatic side chains and the perfluorinated analogues. The authors further quantified the energetic scale of the quadrupole interaction between phenyl and perfluorophenyl moieties to be ~1.0 kcal/mol, comparable to that of weak hydrogen bonds.
The report by Gao and Zheng clearly demonstrates the aromatic quadrupolar interaction can direct protein-protein interactions in water. This new recognition element greatly expands our toolbox for programming protein assemblies in order to achieve novel materials for biomedical applications.
To read the paper, go to:
Professor Kian Tan's Research is Highlighted in Chemical & Engineering News
A bifunctional amine-phosphine ligand designed to simultaneously bind the substrate and catalyst in hydroformylation reactions is proving to be a versatile directing group for organic syntheses, report Professor Kian L. Tan and coworkers of Boston College (J. Am. Chem. Soc., DOI: 10.1021/ja1036226). Tan's group has previously shown how this so-called scaffolding ligand's amine group helps bind an olefin substrate and the phosphine group helps bind a rhodium catalyst, leading to regio- and stereoselective hydroformylation of mono- or disubstituted olefins. Stoichiometric amounts of phosphorus-based directing groups were previously required to carry out such reactions, but by reversibly binding the substrate and catalyst, only a catalytic amount of the scaffolding ligand is needed. Tan, Xixi Sun, and Kwame Frimpong have now demonstrated that the scaffolding ligand selectively directs formation of a quaternary carbon, rather than preferentially forming a lactone, in the hydroformylation of styrene-based substrates (reaction shown, R = aryl groups). A general method of using hydroformylation to create highly substituted carbon centers in olefins had been lacking, the researchers note. The synthesis "demonstrates the power of directing groups to overturn inherent selectivities of reactions," they write.
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Posts in the 'Diamond Rings' Category
{Partner Love} Diamond Colors Adds The Unexpected To Your Bling
Diamonds may be a girl's best friend — yes, even for us Broke-Asses! — but sometimes we want something juuuust this side of ordinary. Something to really make us stand out, but without sacrificing our love for the gem. Or the dolla billz in our budget.
Here's where Diamond Colors steps in. The retailer's rainbow-like line of natural colored diamond rings will make you stand out like whoa. All the diamonds are natural in color and each color has its own meaning. Why not show your eternal love with a gorgeous pink diamond ring? Or bring out some unexpected personality with a yellow gem?
Oh, and don't think that just because you're a Broke-Ass, you don't deserve some beautiful bling, too. Diamond Colors has loose and set diamonds for the whole spectrum of budgets. If you already have that gorgeous heirloom setting you want, but desire a loose pink diamond, they've got you covered.
Confused about what to get, or what color band and type of setting will make your blue diamond look smashing? Oh, Diamond Colors has that covered too. With personal designers posting up shop at their New York HQ, but available for consultation over the phone, you can work to make your precious truly yours. And Diamond Colors' vast experience in the land of glam helps ensure you get the best customer service, and a sparkler will leave you a-twitterpated.
Who Wants To Win Some Diamonds?!?
UPDATE: WE HAVE A WINNER! (See Below)
I used to love treasure hunts as a kid. I always would imagine that I was a pirate on the hunt for burried treasure. Sadly, the most exciting thing I would ever find was an old tin can. Can you imagine how excited I would have been if I had found actual DIAMONDS?! Well, since Whiteflash.com likes a treasure hunt as much as we do, one lucky winner will get to go on a treasure hunt and come home with shiny sparkly real life DIAMONDS.
The rules are simple and pretty fun. Heck, I would play even if I didn't want to win any diamonds, but who doesn't want to win diamonds? I just like saying it DIIIIIAMOOOOOOONDS! ooooh that feels good! All you have to do is find the diamond set items from Whiteflash.com that are hidden in the 3 pictures below. Once you have found them, head over to Whiteflash.com to find and identify each item's name. Then send an email to email@example.com with the names of the three items you have discovered on your hunt. From the correct answers we will randomly select a winner and tadah the winner will have DIIIIIIIAAAAAAMMMMMOOOOOOONNNNNDDDDS in their hand. Or more likely on their wrist, since they will have won the Flash-tastic bangle hidden below.
So get hunting, because this contest ends exactly one week from… now. LET THE TREASURE HUNT BEGIN!!!
Hundreds of great entrants but there can only be one winner, drum roll please…. Congratulations to our lovely reader Andria Chang!!!
You have just won the colorfully blingtastic Shared Prong Diamond Bangle from WhiteFlash.com. These dazzling bangles are offered in a variety of diamond/gem combinations and are always set with the premium line of Whiteflash ACA diamond melee.
Congratulations Andria and thanks so much to all our entrants!

subset: commoncrawl


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Of empty purses and tattered pockets: Stitching funding back into gender and ICT
Thandiwe Mathenjwa, a 43 year-old single mother of 11 from KwaZulu-Natal,South Africa, opened up a discussion on financing for ICTinformation and communications technology. ">i at the UN in this year's session of the Commission on the Status of Women. She's part of a self-help, income generating group called Fancy Stitch, a supplier of artistic greeting cards, picture frames and clothing. Her voice, image, work and experience - her digital story - kept the policyi and finance debate away from abstraction and rooted in women's realities.
The panel on women's communication rights "Why the purse feels empty: Financing for women's equitable access to informationAPC Internet Rights Charter">i and communication technologies" brought together donor, development and civil society perspectives on the issue.
Why should gender and ICT projects be funded? Source: Governance for sustainable human development: A UNDP policy document (Glossary of key terms) and Wikipedia">i
Ireen Dubel state"government" in this glossary). As a general rule, "state" should not be capitalised.
Source: Governance for sustainable human development: A UNDP policy document (Glossary of key terms) and Wikipedia">id that HIVOS, a funding agency in the Netherlands, prioritises information and knowledge for development. "We think that access to information and its transformation into knowledge enables people to express their voice, to develop self esteem, dignity - in other words it empowers people to make informed choices, to make claims and participate in decision-making....in brief, knowledge is power."
Indeed, sharing Thandiwe Mathenjwa's story was possible thanks to a digital storytelling workshop run by Women'sNet, gender and ICT advocates and trainers in South Africa. Twenty-seven women from Fancy Stitch took part in the workshop originally designed for 10. Twenty-seven digital stories were made in Zulu, by women who had never used a computer before.
And yet, organisations such as Women'sNet struggle to find funding for the important work they do.
Funders like HIVOS, which recognises the importance of ICT and that they are not gender neutral, are few and far between. "In an existing discriminatory environment, the way that ICT are produced, perceived, used, applied, monitored, governed - there is a gender bias related to the gender inequities in society at large," observes Dubel. HIVOS sees information and knowledge strategies as vital to women's organisations and movements. The emphasis is not so much on the tool, but on women becoming "ICT-savvy", with ICT responding to women's agenda of empowerment
Source: Wieringa, 1994
Is the problem an empty purse, or no purse at all?
While funding for grassroots infrastructure and ICT work was initially available in the 1990s, this support quickly disappeared as infrastructure was left to the private sector; which, panelists observed with dismay, did not necessarily have the capacity or interest in reaching unprofitable sectors of society, for example rural areas.
The Task Force on Financial Mechanisms issued a report on the state of financing ICT for developmentHandout: ICTs for Development (ICT4D), Multimedia Training Kit (part of APC's ICT policy training curriculum)">i during the World Summit on the Information SocietySource: APC ICT Policy Handbook and APC Annual Report 2005.">i (WSIS) in 2005. It pointed out that both public and private sectors had not properly addressed issues of capacity-buildingSource: "Capacity building: A buzz word or an aid to understanding?" by Ben Green and Mike Battcock, Developments Magazine, 2001">i, communications and connectivityPCMag.com">i in remote areas, regional backboneSearchTelecom.com">i infrastructure, or broadband capacity. ICT application and integration in health, education and development sector programmes was found lacking. The report also stated that government"state" in this glossary). As a general rule, "government" should not be capitalised.
Delving into new pockets
However, in the case of ICT, countries have a local, dedicated mechanism for financing in the form of Universal Accessi Funds (UAF), commented Willie Currie of the Association for Progressive Communications (APC). Telecoms were required to pay a percentage of their turnover into these funds, which in some countries have served to finance rural infrastructure or telecentreis. Typically, the funds are tapped by the private sector and focus on infrastructure. In some countries, they are untouched and represent a significant amount of resources.
Currie considers that given advances in mobile technology, universal access funds could be repurposed to support community networks as well as the content, application and capacity building necessary to sustain them. He encouraged women's movements to champion the "transformation of UAFs into community friendly sources of finance" at all policy levels, including the upcoming fora of the Global Forum on Access in Malaysia and Connectivity and the financing for development review of the Monterrey Consensus in Doha this year.
Radhika Lal called for gender and ICT advocates to join forces with universal access activists, but also observed that making inroads on existing funds through gender responsive budgetting is necessary. Information society issues touch on many areas such as service delivery, livelihood creation, and inclusion which are not considered from gender equitygender equality.">i viewpoint in national budgets. Lal also encouraged activists to take a closer look at ICT regulatory and financing mechanisms. We need "licensingi in the name of equity," she insisted, "you are not going to get responsive service delivery where the social norms are adverse towomen's participation without women being explicity involved." She recalled rollouts of telecentres that did not pay even minimal attention to stakeholder needs.
Silicon Valley philanthropists represent a new funding horizon, and the possibility of private sector partnership that for many is unexplored. Lal cautioned not to see the northern private sector as the deep-pocket solution to funding troubles, but to also explore southern private sector alliances. "Innovation can happen with the southern private sector because they understand some of the issues better, the costs, the kind of services to focus on, the local lacks."
Who needs whom?
In closing, Chat Garcia Ramilo of the APC Women's Programme urged people to keep in mind that telecoms and Silicon Valley companies owe their success to consumers, to the general public, to us. "All of us contribute to this wealth," she stated, insisting on women's right to influence such funds in favor of gender equity.
The panel "Communications Rights for Women: Why the Purse Feels Empty. Financing for women's equitable access to information and communication technologies" was organised by the Association for Progressive Communications Women's Networking Support Programme, the International Women's Tribune Centre and the UN Division for the Advancement of Women during the 52nd session of the Commission on the Status of Women in New York, February 29, 2008.


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Hold down Control (PC) or Command (Mac) key + mouseclick to select more than one option
|Avg. Dinner Entrée
|Greater than $25
|$18.01 - $25
|$12.01 - $18
|$7.01 - $12
|Less than $7
Posted by Neighborhood Foodie on 06/30/2012
The location is beautiful. The food is okay -- good enough that we have been returning customers for eat-in and take-out but of late every time we order the order is incorrect. When eating in this is somewhat tolerated but when getting take out you call back and they tell you well I dont have that written down. And that is my fault? Then they want you to go there and pick up the correct order ... not send somebody out to correct the mistake. This has happened 3 times in a row. Solution: we are not going back there again for mediocre incorrect food.
Posted by cat m. on 07/17/2011
I just came back from a disappointing lunch at Kaijou. We were the only people dining there. The wait staff was rude and got into an argument amongst themselves. I told them to be quiet. Instead, they took the argument to the outdoor seating area. We were sitting right by the door and could still hear them. My hot entree also came out about 10 minutes earlier than the sushi (probably because the chefs at the sushi bar were also involved in this argument they were all having). By the time the sushi arrived, my food was cold. Poor service, unappetizing food. I did not go out to lunch to hear people screaming at each other.
Posted by Sharanika on 06/08/2009
Okay so one will definitely want to come to this place for the breathtaking waterfront view. But the food is definitely not worth the extremely high prices. Take out Chinese is better than this!
Posted by anonymous on 03/17/2009
We went to Kaijou a couple of days ago, and I must say that their sushi is good for the low price. But I was unhappy about the service, the girl hardly spoke English, and it was hard to catch her attention. In fact, the waiters seem to enjoy it more to talk to each other than care for their customers, which was quite annoying. This is why I would consider to use their delivery service next time, but I won't come back here to eat anymore!
Posted by Anonymous on 11/06/2008
Ordered delivery for the first time. highly disappointed. Spicy tuna roll had little scales in every bite. Sloppy job, in my opinion and overall makes for an unpleasant eating experience. Alaskan roll used smoked salmon and no where did it indicate that. Who does that? Ruined the roll. Only good thing was the Black cod roll, yum! But overall will never order from here again because of the sloppy job done on the spicy tuna roll. It's a shame.
Posted by Kenichi on 10/05/2008
I recently visited this restaurant, and I liked it! They got a nice view from windows in which you can see statue of liberty. Food is good although they do not serve authentic Japanese sushi. It's rather fusion style western-Japanese cuisine. Only complain is waiters/waitresses limited English ability, but overall atmosphere is good. It's worth traveling to this downtown restaurant, especially sunset time!
Posted by Jessica on 09/22/2008
I am obsessed with their Hibachi menu as well as their fried rice. I order from Kaijou at least 3x a week and it's always amazing. They are also really great at customer service and the views are great.


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Step 1: You'll need...
A pom-pom maker (the one I used was fancy and hinged, but you can also use two cardboard doughnut shapes)
A crochet hook (to match the size of the yarn you are using for the legs and head)
Step 2: Crochet the Legs
Crochet 1 sc in each stitch around until the leg is the length you want it, mine were short and stubby and only two rounds of this.
Change to the body colour and do one more round of 1 sc in each stitch. Make sure that you start and end with lots of extra yarn.
Tie the two long ends together, and tuck any other loose ends into the leg. Make sure to keep the two strands that are to body colour loose, as you'll need them to join the legs to the body.
Make three more for a total of 4 legs.
(I am using the American terminology, so sc, or single crochet, is done like this)


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Palin and Ayotte meet for breakfast
Kasie Hunt relays word from Portsmouth that Sarah Palin just sat down for breakfast there with New Hampshire Sen. Kelly Ayotte.
Palin endorsed Ayotte last year during a competitive GOP Senate primary. Ayotte's a popular former state attorney general whose endorsement could be a big help to someone in 2012.Continue Reading
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We continue our exclusive chat with Luis Suarez for LFCTV GO subscribers as he talks openly about being a competitive dad, his unyielding will to win and younger years spent in Uruguay.
In his most in-depth interview to date, Liverpool's No.7 opens up like you've never seen him before.
This is the second of a three-part exclusive chat with the Uruguayan - with a further video to follow on Wednesday - and is a genuine must-watch for those who want to know more about Suarez.
You'll need an LFCTV GO subscription to watch; if you haven't got one, why not sign up now and take advantage of our special offer - get 12 months for the price of 10 by entering discount code GO1.
If you are already signed up, simply click play on the embedded video below.
Tagged: LFCTV GO , Luis Suarez , Suarez
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In this course, author Christopher Breen examines Mac OS X Mountain Lion, the latest version of the Apple operating system. The course takes a look at the enhancements to messages, contacts, calendars, mail, Safari, and expanded iCloud remote storage options, as well as brand-new features such as AirPlay mirroring, which makes it simple to wirelessly project your Mac screen onto an Apple TV–connected television, the Game Center app, Dictation, and Gatekeeper security protections.
Welcome to Mac OS X Mountain Lion New Features. I am Chris Breen. In this course I'll outline the major changes that are introduced with Mountain Lion. Security is a big part of Mountain Lion, and we'll take a long look at how that's implemented in OS X, and what you can do to configure your security settings so that you'll be safe from malware threats, while at the same time acquire and use the software you need. Mountain Lion introduces Notification Center, a central repository for alerts. I'll show you where it is, what it can do, and how to configure it.
Mountain Lion introduces the ability to turn your speech into text. If you have a desire to talk to your Mac and see your words accurately captured, tune into the Dictation movie. I'll show you how to use the new Reminders feature to help you organize your life, and there is more. Mountain Lion brings improvements to Mail, Safari--which is Apple's web browser--Calendar, Contacts, and iCloud, Apple's Cloud-based synchronization and storage service. While Mountain Lion may not be the kind of update that takes your breath away, it offers some terrific new features.
Let's get started with them now.
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UAW Solidarity House | 8000 East Jefferson Avenue
Detroit, Michigan 48214 | p. (313) 926-5000
© Copyright 2014 UAW. All Rights Reserved.
The Internet has a huge amount of information on the toxic effects of chemicals. You can download MSDS sheet from several locations however it is best to obtain MSDS sheets directly from your employer. The National Library of Medicine has a number of searchable databases that will provide lists and brief descriptions of studies done on health effects of chemicals or industry types. EPA maintains a site where you can find less toxic chemical substitutes.
Metal Working Fluids: New Research
Selected papers from a symposium on metalworking fluids conducted in October 2002 have been published. The abstracts are available on line.
The symposium includes papers by Frank Mirer and Dennis O"Brien of the UAW Health and Safety Department, Ford, Chrysler and GM scientists, a NIOSH scientist reporting on a UAW-represented plant, as well as some by investigators supported by joint research funds. Paper topics include: review of air quality measurement techniques; mapping problem areas in the plant; respiratory health studies; fluid chemistry; and ventilation control methods. These data support our lawsuit to compel OSHA to resume efforts to set an MWF standard, and also were part of the UAW motivation to pursue the lawsuit.
Applied Occupational and Environmental Hygiene Volume 18 Number 11 (2007-03-26)
Try the 'search" button at this site to look up chemicals by name and CAS #. Also available is the annual report on Carcinogens. The National Toxicology Program is a collaborative effort between several government agencies.(update 2.24.03)
National Institute of Occupational Safety and Health
From this page you can access the NIOSH publications and a topic index. Look for the NIOSH Pocket Guide on-line and the various criteria documents for chemical and process hazards.(update 2.24.03)
This is the online version of the NIOSH Pocket guide to Chemical hazards. This is a a good source for Personal Protective Equipment.(update 2.24.03)
Agency for Toxic Substance Disease Registry (ATSDR)
ATSDR was funded to study the health effects of chemicals that are found in contaminated sites. Check out ToxFAQs for quick synpsis of health effects. Check out the Minimum Risk Levels (MRLs) and compare these to OSHA PELS!(update 2.24.03)
PubMed: Abstracts from Biomedical Journals
PubMed, a service of the National Library of Medicine, provides access to over 12 million MEDLINE citations back to the mid-1960's and additional life science journals. PubMed includes links to many sites providing full text articles and other related resources. (update 2.24.03)
A cluster of databases on toxicology, hazardous chemicals and environmental health.
These include:
HSDB (Hazardous Substance Data Bank)
This provides a chemical specific search that produces a report on human and animal toxicity, safety and handling and environmental fate. This is a good place to start a search using key words like "spray paint" or specific chemical names.
IRIS (Integrated Risk Information System)
This data has been used to assess human health risk.
(update 2.24.03)
New Jersey Hazardous Substance Fact Sheet
These fact sheets provide a quick reference to specific chemicals that may be listed on a MSDS sheet. (2007-03-26)
Material Safety Data Sheets (MSDS) - 1
This is the one of three sites that maintain SIRI MSDS searches.(update 2.24.03)


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COLUMBIA CITY ŌĆö Purple ribbons and banners were hung around the Whitley County CourthouseŌĆÖs gazebo Tuesday in observance of National Domestic Violence Awareness Month.
Members of Columbia City High SchoolŌĆÖs Key Club and the Whitley County Domestic Violence Task Force joined County Commissioners in proclaiming the significance of this particular cause.
ŌĆ£This is important to our county. We need to get the word out,ŌĆØ said County Commissioner Don Amber. ŌĆ£Tell people what the purple stands for. ThatŌĆÖs how we will make change.ŌĆØ
The downtown decorations will serve as a reminder throughout the month of October of the reality of domestic violence.
ŌĆ£This happens here in our county,ŌĆØ said Natalie Lewis, the task forceŌĆÖs director. ŌĆ£ItŌĆÖs a county problem that will only be stopped if we work together.ŌĆØ
In addition to the decorations, a workshop is slated for Oct. 9 from 8:30 to 3:15 p.m. at Eagles Nest Event Center.
To read the rest of this story, see the Oct. 2 issue of The Post and Mail. Don't have a subscription? Call (260) 244-5153 or subscribe to our e-edition. For breaking news, sports updates and additional coverage, bookmark the homepage and find us on facebook and twitter.