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Will an international coach get a shot in the NBA?
The Dallas Mavericks were thought to be tiptoeing out on a shaky limb in 1998 when they traded for a skinny forward out of Germany named Dirk Nowitzki.
European players, especially one from a basketball no-man's land, were considered soft, and the conventional thinking was that a franchise could not win a championship with such a player as the cornerstone.
Nowitzki proved everyone wrong, of course, developing into an MVP, winning a title and helping to usher in a new line of thinking with regard to international players.
Now practically every team is scouring the globe for top-shelf talent and has come to recognize that some of the professional leagues in Europe rival or exceed Division I colleges for competitiveness and skill.
Fifteen years after Nowitzki was drafted, the NBA has an international flavor, evolving into a more open, free-flowing style of play in a game that had grown rugged around the turn of the century.
A record-tying 84 international players were on NBA rosters when the league opened play this season, and franchises in Dallas and Minnesota had their hopes hinging on the recoveries of European stars.
With so many foreign players having so much success, the next step could be bringing in a coach from one of the power programs overseas to run a team.
After facing some of the top candidates during the London Olympics, Team USA head coach Mike Krzyzewski has no doubt it could work.
"There is no question that an international coach can be an NBA head coach," Krzyzewski said during the Americans' run to the gold medal. "These guys are terrific in their preparation, and a lot of the international players are playing in the NBA, so it is not a stretch."
Job security in the NBA is as volatile as any professional league, creating openings and searches for the next Phil Jackson almost on a monthly basis.
This season alone, the Los Angeles Lakers fired Mike Brown after just five games and the Brooklyn Nets dismissed Avery Johnson three weeks after he was named Eastern Conference coach of the month.
Often times, those jobs are filled by retreads. Washington Wizards coach Randy Wittman has had three head coaching jobs despite being nearly 150 games under .500 for his career; Johnson's abrupt firing thrust P.J. Carlesimo into his fourth head job.
They're hardworking coaches with deep reservoirs of basketball knowledge. But just like in 1998, when the Mavericks traded a standout from a traditional college basketball program -- Michigan's Robert Traylor -- to the Milwaukee Bucks for Nowitzki, the time could be drawing near for a forward-thinking franchise to go in a fresh direction.
"I would think we're getting closer," Timberwolves international scouting coordinator Pete Philo said. "If you took the top 10 percent of coaches in Europe and the top 10 percent here, they're pretty close. These guys over there can flat-out coach. We have some outstanding coaches here as well."
Top candidates could certainly include David Blatt, who resurrected the Russian national program and led them to the bronze medal in London; Ettore Messina, a legend in Europe who rose to prominence in Italy and now coaches Russian power CSKA Moscow; and Rimas Kurtinaitis, the only coach to win the highly competitive Eurocup twice.
"That is going to be a very courageous decision on the part of an owner and a general manager," the American-born Blatt told the Associated Press. "Up to this point, it's been obvious they're not willing to take someone directly. And in fairness there are a lot of great coaches in the NBA that are in line and deserving.
"But much like what the Russian national team did, someone at some point is going to want to take a different direction and to make a break from the norm and to courageously step up and say, 'Hey, we want to do things a little differently and we're not afraid.' When that decision comes, I hope I'm a guy they consider."
The challenges for an international coach in the NBA would be many. The different rules -- from goaltending to zone defenses to the time of the game and the width of the key -- would be minor adjustments. But handling a much more demanding schedule with up to four games per week versus playing twice a week in Europe, and tailoring the approach to accommodate those differences would be paramount.
A coach with no domestic roots tapped to take over right from the start would also have to deal with the same skepticism that Nowitzki faced.
"I say this respectfully, but our players have to buy in," Philo said, speaking in general terms and not about the 'Wolves specifically. "If your players don't buy into your head coach, they're not going to play as hard. Your guy has to come with a little cache or your marketing department better do a good job promoting the guy."
Timberwolves forward Andrei Kirilenko has played in the NBA 10 years and also is a star in his native Russia, spending last season playing for CSKA Moscow. European coaches, in general, are more taskmasters, Kirilenko said -- an approach that has been proven to be less and less effective in the NBA as the years have gone on and salaries have skyrocketed.
So who will make the leap? The Nets would seem to be a logical choice with Russian owner Mikhail Prokhorov, but they appear to be trying to lure Jackson out of retirement for another run. The Timberwolves (Rick Adelman) and San Antonio Spurs (Gregg Popovich) have two of the most respected coaches in the game.
They've also been more open to bringing in international players than most teams, which would indicate a willingness to at least consider the idea down the road.
"I think that's a big step right now, but I can't deny someone might not pull that trigger," Karl said. "It might be an organization where someone wants a new face, a new script. I can't deny there's some guys over there that probably have the talent."
Blatt, who coaches Maccabi Tel Aviv in Israel, made it clear in London that he'd like to be the first one who gets a chance.
"If you're asking me could I do it, would I like to do it? Absolutely," Blatt said. "If you're asking me is it going to happen anytime soon? I'm kind of doubtful."


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Five Reasons for Software Certifications
Several people I respect (notably Gary McGraw) as well as others that I don't really know (e.g., the author of this blog post "5 reasons why software certs suck"), have argued vehemently against certifications recently. I am a subject matter expert for the new Certified Secure Software Lifecycle Professional (CSSLP) certification. I help write the exam questions. Obviously I wouldn't do it if I didn't believe it had some value. So I'm going to try to write a few reasons why they are worthwhile.The author of the blog post is sorta contradictory. In one case he says certifications don't matter because the companies he respects (e.g., Microsoft and Google) as well as the people he admires (e.g., Wozniak) don't have them. He simultaneously, and contrarily says that there are times when you'll be passed over in hiring because another candidate has more certs than you (i.e., because the certs do matter). Which is it? It is neither and it is both.
1. Certifications provide common context and vocabulary
Someone who has completed a certification, no matter how trivial, has assimilated some of the vocabulary, context, and culture that the certification tries to document. I expect someone holding a CISSP, CSSLP, GIAC, GSEC or similar certificate to speak a certain language and understand certain terms when I say them. Let's not mistakenly ascribe some loftier goal and then be frustrated when the certification's candidates don't live up to them.
2. Certifications are about minimum competence, not maximum
A certification is meant to recognize something you know. There are those who cram for a certification exam, in order to appear, for a brief moment, to know the material that the exam tests. No one thinks that the people who study momentarily are the same as those who have a long career behind their passing score. It's very difficult to design a test that cannot be crammed while staying within the bounds of cost-effective administration. Think of it this way: Mario Andretti has a drivers license in his wallet. So do I. His driving skills and mine are not comparable at all, but we both passed a test that certified a minimum competancy. He also has credentials for Formula 1 racing and years of career racing that I do not. Let's not, for a moment, consider trying to capture his experience (or Microsoft's or Wozniak's) in a test. We are just establishing minimum competence.
3. The world needs objective measures that are comparable
Ignore for a moment what value you place on the content of the exam. If the exam is carefully standardized you have a tool for comparison. If you have ever had to hire someone, you know how people make buzzword-compliant resumes today that say almost anything that could possibly help get the person a job. As a hiring official you have to sort out the BS from the actual capabilities. With a certification you have a better starting point for that weed-out process. If I see J2EE on a resume, I have a long series of questions that will get at their experience one way and another. If I see CSSLP on the resume, I know what they should know.
Now earlier I said ignore the value of the content. Now, let's evaluate the value of the content of the cert. If it has the ability to establish context and vocabulary and minimal familiarity with topics, I can work with that. If I come to discover that it has more value than just vocabulary (as a CCIE does), then I learn to ascribe more meaning to finding it on a resume.
4. Stop insulting everyone
Both the testsquad blog post and the popular anti-cert crowd make accusations of brainlessness. They claim that once you get a cert, you'll feel the rush like heroine and have to keep getting more and more certs to feed your addiction. They also claim that employers myopically focus on certs and somehow overlook the true value of the candidate. I say that the employer who overlooks a candidate's true value because he sees CSSLP on the resume would be equally duped by the long list of buzzword-compliant terminology and some good interview coaching by a placement agency. The root of that problem is the interviewer/employer, not the certification. I don't see anything inherently worse about a cert than a good coach and a bunch of buzzwords. If anything the certs are at least moderated and standardized.
5. This train is leaving the station
You can be on it or under it. The industry is attempting to create standardized comparison for various kinds of capabilities. We need to find a way to do this with integrity and value. The ivory tower people say "you can't tell if someone really knows their stuff based on a multiple choice test." There are lots of NP-Complete problems in the world that we don't think we can solve in polynomial time, yet we can apply heuristics and do various things to limit how much time we spend solving them. We need to apply the same sort of best-effort focus on quality while balancing real-world constraints. Planting our heads in the sand and saying it can't be done is not an option. The people who want the standardization of capabilities will continue to push. Those of us smart enough to know how hard this is to do can either help, or shut up. Complaining, though, is not an option.
Excuse the spelling, spellcheck has failed me.
Definately disagree with most points.
point 1. The ability for a private corperation to control the lexion is called marketing. You gain a common lexion by reading the refereed research not going to a cert class. Pipes are called pipes because thats what K&R refer to them as in their AT&T unix paper not because its in a learning tree text book.
point 2. There is no general standard for minimum competence. Every job is different, an expert in one scenario is a beginner in another. It is rare that the interviewers in HR know what bar a certification sets. The SME's that interview an individual next have their own set of questions that are tailored to the task at hand. While a cert class may allow a person to answer these questions the person performing the interview certaily doesn't care how an individual got that knowledge. To use your example, the intervier doesn't care if its you or mario, only if you can take a turn of a given radius at 60 mph. He doesn't care if you obtained that skill on the race track or commuting to DC. Using a cert to tailor interview questions is just well, lazy. You are tailoring the job to the cert not the company's needs. That qualifies as WRONG and BAD… see internet dictionary.
point 3. First, the world doesn't need anything(well maybe love), people need. If you are one of those people, while a cert is comparable it certainly isn't objective. If they still haven't perfected IQ or SAT testing, how does a computer cert test stand a chance. The aformentioned have been around waaaaay longer.
point 4. Well, I agree with you here. But, its the internet what'd you expect. I also don't see this as a vailid argument for or against certs so I think you sould change your title to 4 reasons not 5.
point 5. This is just untrue. For any high quality work you are rated on what projects you were apart of or what enviornments you worked. MCSE, CISSP, and CNNA only help the fledgling computer professionals get interviews, which accounts for a very small part of the market. Amdhal says look elsewhere. It's your reputaion, accomplishments, and contacts that give an impression of your future ability to solve a problem. Most interviewers are willing to overlook the fact that you lack a cert or the spicific knowledge the cert implies you have once you have experience. Based on your track record they know you'll learn and solve their problem. In case you were wondering we have certifications for learning potential….. BA, BS, MA, MS, MD, PhD … etc.
I'm not saying there isn't enlightenment to be had by taking the certification exams or classes. I believe them to be industry's version of acidemia. I'm just saying to rely on them as an interviewer is foolish…and lazy. Certs are a good tool for education, but they will never be a bar, minimum or otherwise, to judge a persons potenial. The best they may ever be able to say, is that an individual is ready to take the next cert class.
Point 1
Unfortunatly in practice your argument very rarely holds. For examples look at VMware, sun, and microsoft literature. Product names and marketing names are substituted for the conceptual names the inventor or field of research may use. Sometimes companies purposly make names obsure to suborn brand recognition. A name comes to mind…. cigi… wait I lost it. As a matter of fact one of my top complaints about certifications is that they teach the incorrect vocabulary AND limit how people think they can apply a particular technology. I have issues with this in practice working with a bunch of very good, very qualified MCSE type individuals. The microsoft name or way of doing things limits their way of thinking as to activly interfere with problem solving.
Point 2
Again, certs only prove you know what was on the test at the time. Unfortunatly compotence is a degree of experience and historically difficult to measure. To use the driver's license example again…. With computer certs there is no road test, no practical way to judge. Yes, the person knows what a steering wheel is conceptually, but can he use it to turn the car. Or lets take the FAA, to be type rated in a jet you take a checkout flight with an FAA inspector who also has a ton of flight hours. I don't see this in any certification process. Most accredited Universities acknowledge this failure in their cirulum and compensate with interships. Personal experience shows a certified person knows deeply the vocabulary in a field, but only has a vague notion of the underlying concepts. Since most people are profecient with language, teaching them definitions is the least of my worries.
Point 3
Well, my experience is that, as currently implemented, they have negative usefulness. But, thats not to say that can't change. I think certs can be useful, they just aren't right now. The major problem is bias and sandboxing of ideas. Both shortfalls which can be overcome, but aren't do to the fact organizations use certification training as a marketing tool.
Point 5
Ahhh but in practice there are certification classes. You can't fiat away what is because the world doesn't conform to how you think it should be. The fact is there are CERT factories out there and they produce most of the people who have a mature cert. They base their multi-million dollar business on the fact that the certificate is valuable to have. They want to churn as many people through the program as possible sucessfully to justify tuition. They do not let silly things like comprehension and learning get in the way. Additionally and unfortunaly, to accomplish this goal, they subvert the testing process. The problem with the cert is not the mnimally qualified individuals, its the wrongly certified individuals.
As an aside, I have seen certifications in the computer field be useful, not as a measuring stick, as a starting point for curious minds. The question I ask an interviewee is what have you done with your certification outside of work. The ones who have persued interesting side projects have always been the most sucessful hires.
As a correction to point two there is one exception I know of where there is a practical test. Some of the CISCO certifications require lab work. But there is not "check out ride". However, this is the exception not the rule.
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The George Washington Encyclopedia will be the first and only online encyclopedia exploring the life, career, and legacy of the first President, and will help support the opening of the Fred W. Smith National Library for the Study of George Washington in 2013. Entries will cover a wide spectrum of historical fields, including: social, cultural, political, military, and culinary history, allowing researchers to utilize the encyclopedia as a comprehensive gateway for information about George Washington. The encyclopedia is aimed at general audiences (high school level and above) and will provide informative, well-researched, and authoritative articles that adhere to the highest academic standards, including full source citations.
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World Allergy Congress News & Updates
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Plan now to take part in the XXII World Allergy Congress (WAC 2011), the biennial scientific meeting of the World Allergy Organization (WAO), in Cancún, México, 4-8 December 2011. For its 22nd Congress, the WAO is partnering with its Member Societies in México: the Mexican College of Pediatricians Specialized in Allergy and Clinical Immunology (COMPEDIA) and the Mexican College of Clinical Immunology and Allergy (CMICA). Delegates may count on science from around the world, continual learning, a vibrant community of colleagues and a convivial atmosphere. Attendees will also have the opportunity to:
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Already there is dispute over the cleanliness of El Salvador's bellwether legislative elections, the first the nation's leftist guerrilla movement
hasn't boycotted. But despite fraud complaints - the vote was March 10 and some ballots are yet to be counted - and despite a U.S.-style turnout (about 50 percent by one estimate), freewheeling politics appears to have made a cameo appearance in this sad land where 75,000 have died in civil war.
Whether it can endure, of course, is another question. But just this once, we'd like to see the positive accentuated in El Salvador. While President Alfredo Cristiani's rightist Arena Party may have clung to a slight majority, the left-wing coalition called the Democratic Convergence appears to have won a toehold in the legislature - a tentative sign that the often-oppressed left in El Salvador can flex electoral, as well as battlefield, muscle.


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Pumpkin Photo Centerpiece holds your Autumn Memories
Our Guest Contributor is Camille Dawn of Welcome to The Mother Lode
Fall is my all-time favorite season to take pictures. I absolutely love the dark, rich colors and moody lighting that really play up the traditional fall themed photographs – playing in the leaves, picking pumpkins at the patch, and of course the chosen costumes and trick-or-treating action on Halloween night. Our daughter also happens to have a late October birthday, so we always take tons of pictures during this time of year.
Looking back at these pictures, I am noticing that the pumpkin she picks from the patch each year keeps getting a little bigger, her costumes a little more detailed, her candy bag a little more full.
I loved putting together this project, looking at these photographs documenting the growth of our little family as the seasons change, tucking them behind the twine circling the pumpkin, seeing the progression over time.
This finished project has only been on our tabletop for one evening and has already been such a fun centerpiece – lots of lovely reminiscing and lively conversation from brainstorming this year's costume ideas to the eager plans underway for our annual trip to the pumpkin patch.
These are so easy and fun to make – make a large one for your Fall tabletop, or a whole group of them – one for each child perhaps? Older children will have fun helping with the hammering and stringing too.
You will need:
- Large pumpkin
- Hammer
- Nails
- Twine
- Photographs
My daughter wanted to help, so I used one nail to poke guide holes where I wanted the nails to be placed around the top of the pumpkin, and again around the base of the pumpkin.
Placing the pumpkin on its side was the easiest angle for hammering the bottom row of nails. We also found that me starting the nails was easiest – then my daughter didn't need to hold the nails while getting them started, keeping her fingers safe.
For the stringing, start by wrapping one end of twine around a bottom nail and tying securely in a knot. Then bring the twine up to the next nail slightly to the right, then back down again. Continue in this zig zag fashion around the entire pumpkin. I had to reposition, add and remove a few nails here and there when the spacing of the twine seemed off – just eyeball it and make changes as necessary.
If your daughter is like mine, you may need an extra pumpkin to allow for a bit more freestyle expression with this project. We discovered that even though her creative design did not lend itself well to holding photographs, it did make an excellent spider web!
Here's the finished product. It's a little early for pumpkins in our area so these are smaller than I was hoping for – I will be doing this again after our trip to the patch when the larger pumpkins are ready. The pumpkin on the left is actually a craft pumpkin from Michaels. I do like the idea of saving it to reuse each year, but I either need to print smaller images or find a larger craft pumpkin.
Camille Dawn writes and crafts daily at her personal blog Welcome to The Mother Lode. It's fabulous and inspiring.


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The Porter Cable 560 Quik Jig Pocket Hole Joinery System uses an automatic depth control system that allows for easy set up for various material thicknesses. The Variable Speed Bushings, Self Adjusting Clamp, repeatable clamp, Screw Length Gauge, Built-In Drill Bit collar and Removable Dust Port make the Quik Jig Pocket Hole Joinery System a great addition to any tool collection.
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Brent Harvey lauds combined training sessions between North Melbourne and Geelong
- From: Herald Sun
- January 23, 2013
BRENT Harvey has lauded the unpredictability and extra competitiveness North Melbourne's training clashes against Geelong have added to the Roos' pre-season.
In an unprecedented move, twins Brad (North) and Chris Scott (Geelong) have organised match simulation hit-outs against each other's team every Friday for a month.
The first two sessions have consisted entirely of end-to-end stoppage drills, with a coach up either end of Geelong's home ground, Simonds Stadium, calling the shots.
Onlookers said the atmosphere has been serious, with neither team engaging in friendly discussions or handshakes before or after the sessions.
Geelong captain Joel Selwood has been a standout, while Cats veterans Joel Corey, James Kelly (hip), Jimmy Bartel (foot) and North match-winner Daniel Wells (achilles) have all taken part.
"I like it. I was really sceptical at the start, (thinking) it's only going to take one bloke to get someone into the ground and it's going to be all over," Harvey said.
"As long as we treat them very similar to what we treat each other at training -- you get the opportunity to bury someone, you just don't do it this time of year -- (so there's) the respect.
"It's different, you get to see how Selwood and Stevie Johnson train and for our young boys it's a good experience.
"Tell me five years ago, (we'd be training with Geelong) I'd be saying no, not a chance at all.
"But it's worked really well."
The 20 and 40-minute sessions have been behind locked gates at the Cattery, allowing the clubs to trial set-ups and game styles away from other clubs' prying eyes.
Clubs cannot conduct full-scale matches against each other until the NAB Cup.
Harvey said the sessions have taken the Roos' training to a new level.
"When you're doing your stuff (at normal training) you're mirroring each other, so the mids know what the mids are doing, the backs know what the forwards are doing, where they're leading," Harvey said.
"It's really hard to get great match practice out of it. When you're playing against Geelong they've got no idea and we've got no idea what they're doing, so it's actually a really good exercise."
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Journal of Colloid And Interface Science (v.289, #2)
Editorial Board (CO1).
Use of the liquid–liquid interface for generating ultrathin nanocrystalline films of metals, chalcogenides, and oxides by C.N.R. Rao; G.U. Kulkarni; Ved Varun Agrawal; Ujjal K. Gautam; Moumita Ghosh; Usha Tumkurkar (305-318).
The air–water interface has traditionally been employed to prepare particle assemblies and films of metals and semiconductors. The interface between water and an organic liquid, however, has not been investigated sufficiently for possible use in preparing nanocrystals and thin films of materials. In this article, we demonstrate the use of the liquid–liquid interface as a medium for preparing ultrathin films of metals, chalcogenides and oxides. The method involves the reaction at the interface between a metal-organic compound in the organic layer and an appropriate reagent for reduction, sulfidation, etc. in the aqueous layer. Some of the materials discussed are nanocrystalline films of gold, CuS, CuSe, CuO, and Cu(OH)2 formed at the liquid–liquid interface. The results reported in this article should demonstrate the versatility and potential of the liquid–liquid interface for preparing nanomaterials and ultrathin films and encourage further research in this area.
Keywords: Nanocrystals; Ultrathin films; Liquid–liquid interface;
Surface complexation of condensed phosphate to aluminum hydroxide: An ATR-FTIR spectroscopic investigation by Xiao-Hong Guan; Qing Liu; Guang-Hao Chen; Chii Shang (319-327).
Two model compounds, sodium pyrophosphate (pyro-P) and sodium tripolyphosphate (tripoly-P), were employed to elucidate the binding mechanisms of condensed phosphate on aluminum hydroxide by utilizing attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy. Peak assignments for the condensed phosphates in the solution phase and those adsorbed on the surface of aluminum hydroxide were made. Electron delocalization and polarization were employed to explain the peak shifts and the complexation of condensed phosphate with aluminum hydroxide. The tripoly-P and pyro-P were adsorbed on aluminum hydroxide by forming inner-sphere complexes. The adsorbed condensed phosphates were deprotonated in the pH range from 4 to 10. Monodentate, bidentate, and binuclear complexes were formed when pyro-P was adsorbed on aluminum hydroxide, while monodentate and binuclear complexes were formed when tripoly-P was adsorbed. Based on the FTIR data, we proposed that when either bidentate or binuclear complexes were formed, the two oxygen atoms participating in the complexation with aluminum hydroxide could not be originated from the same terminal phosphate moiety. The Al―O bond formed in the complexation of pyro-P or tripoly-P with aluminum hydroxide (AlPO− 3) was not as strong as the H―O bond in terminal HPO− 3. The bridging PO− 2 of tripoly-P did not coordinate with aluminum hydroxide. The real-time ATR-FTIR study on condensed phosphate adsorption revealed that a long contact time between condensed phosphates and aluminum hydroxide particles can result in a transformation of an initially formed species into a thermodynamically more stable phase.
Keywords: Aluminum hydroxide; ATR-FTIR; Complexation; Condensed phosphate; Electron delocalization; Polarization;
Removal of p-aminophenol and p-nitrophenol from aqueous solution through adsorption on antimony, cadmium, and zirconium ferrocyanides by Brij Bhushan Tewari; Marc Boodhoo (328-332).
Adsorptive interaction of p-aminophenol and p-nitrophenol in the concentration range 10 −4 – 10 −5 M and at room temperature ( 30 ± 1 ° C ) was studied with antimony, cadmium, and zirconium ferrocyanides. The interaction followed the Langmuir type of adsorption in general. The p-nitrophenol was found to have greater affinity for the antimony, cadmium, and zirconium ferrocyanides then the p-aminophenol.
Keywords: Removal; p-Aminophenol; p-Nitrophenol; Adsorption; Metal ferrocyanides;
Adsorption of ethyl violet dye in aqueous solution by regenerated spent bleaching earth by W.T. Tsai; Y.M. Chang; C.W. Lai; C.C. Lo (333-338).
The adsorption of basic dye (i.e., ethyl violet or basic violet 4) from aqueous solution onto the regenerated spent bleaching earth (RSBE) was carried out by varying the process parameters such as initial concentration, pH, and temperature. As analytical comparisons, activated bleaching earth (ABE) was also used as adsorbent for the adsorption of the basic dye at various initial concentrations. The experimental results showed that the adsorption process can be well described with the pseudo-second-order reaction model and less fitted by the intra-particle diffusion model. The kinetic parameters of both models obtained in the present work are in line with pore properties of the two adsorbents. According to the equilibrium adsorption capacity from the fitting of pseudo-second-order reaction model, it was further found that the both models of Langmuir and Freundlich appeared to fit well the isotherm data. In addition, the thermodynamic parameters were evaluated based on the pseudo-second-order rate constants, showing that the adsorption of ethyl violet onto the RSBE is endothermic in nature.
Keywords: Spent bleaching earth; Adsorption; Ethyl violet; Kinetic modeling; Isotherm;
Phosphorus fractions and phosphate sorption characteristics in relation to the sediment compositions of shallow lakes in the middle and lower reaches of Yangtze River region, China by Shengrui Wang; Xiangcan Jin; Yan Pang; Haichao Zhao; Xiaoning Zhou; Fengchang Wu (339-346).
Phosphorus is recognized as the most critical nutrient limiting lake productivity. The trophic status and development of lake systems are also influenced by the phosphorus content and fractions and phosphate sorption characteristics of the lake sediments. The phosphorus fractions and phosphate sorption characteristics of sediments in shallow lakes from the middle and lower reaches of Yangtze River region in China were investigated. The results show that the phosphorus contents in the sediments ranged from 217.8 to 1640 mg kg−1; inorganic phosphorus (IP) was the major fraction of total phosphorus (TP); phosphorus bound to Al, Fe, Mn oxides, and hydroxides (Fe/Al–P), and calcium bound phosphorus (Ca–P) were the main fractions of IP. Phosphate sorption on the sediments mainly occurred within 2 h and then reached equilibrium in 10 h. The phosphate sorption rate was closely related to the concentration of fine particles. The phosphate sorption capacity ranged from 128.21 to 833.33 mg kg−1, showing a significant correlation with the contents of Fe, Fe + Al, total organic carbon (TOC), cationic exchange capacity, total nitrogen, TP, Ca, IP, and the ratio of P/(Al + Fe), and it was higher in the sediments of eutrophic lakes than in mesotrophic lakes. Phosphate was mainly sorbed onto Fe and Al particles. The phosphate sorption efficiency ranged from 26.74 to 312.50 L kg−1, and had a strong positive correlation with Fe content. For the eutrophic lake sediments, there were no significant relationships between the phosphate sorption efficiency and the selected physical and chemical parameters. But for the mesotrophic lake sediments, the phosphate sorption efficiency was found to be positively related to the contents of Al and Fe + Al.
Keywords: Phosphorus fractions; Phosphate sorption; Sediment; Middle and lower reaches of Yangtze River region; Lake;
Hydrogen and methane sorption in dry and water-loaded multiwall carbon nanotubes by Li Zhou; Yan Sun; Zhiguan Yang; Yaping Zhou (347-351).
Both H2 and CH4 are clean energy sources. Adsorption was considered a measure to enhance their storage, and many efforts have been dedicated to creating novel materials including carbon nanotubes as efficient carriers for them. In order to understand the uptake mechanism and the viability of practical application, eight adsorption isotherms of H2 on a sample of multiwall carbon nanotubes were collected. The heat of adsorption was determined and an isotherm model was presented. Isotherms of CH4 on the same sample were also collected. While the adsorption on dry samples behaves similarly to that of H2, the sorption behavior of CH4 in the water-loaded sample is quite different and five times higher uptake capacity was observed in the wet sample due to the formation of methane hydrates. However, carbon nanotubes are unlikely to be used as an energy carrier due to its limited surface area and pore volume.
Keywords: Sorption; Hydrogen; Methane; Carbon nanotubes; Uptake mechanism;
Biosorption of cadmium by the protonated macroalga Sargassum muticum: Binding analysis with a nonideal, competitive, and thermodynamically consistent adsorption (NICCA) model by P. Lodeiro; C. Rey-Castro; J.L. Barriada; M.E. Sastre de Vicente; R. Herrero (352-358).
Protonated biomass of the seaweed Sargassum muticum was investigated for its ability to remove cadmium(II) from aqueous solutions. In this work, a nonideal, semiempirical, thermodynamically consistent (NICCA) isotherm was proposed to fit the experimental ion binding data obtained in NaNO3 0.05 mol L−1. This model describes the competition between protons and metal ions satisfactorily. Moreover, it reflects the complexity of the macromolecular systems that take part in biosorption considering the heterogeneity of the sorbent. It was demonstrated in this work that the NICCA isotherm constitutes a great improvement with respect to a simpler Langmuir competitive equation, which was not able to describe all the experimental data satisfactorily. Potentiometric acid–base titrations in the absence of cadmium were made to estimate the maximum amount of acid functional groups (2.61 mmol g−1) and the conditional proton binding parameters, log K ˜ H (3.8) and m H (0.54). The values of the binding parameters for the cadmium ion were chosen to provide the best simultaneous description of the isotherm at pH 4.5, as well as the dependence of cadmium adsorption on pH. Values of log K ˜ Cd (3.1), n Cd (1.8), and p (0.19) in the case of the NICCA isotherm or log K Cd (2.94–3.4) for Langmuir competitive models were obtained. Kinetic experiments were performed at two different pH values (3.0 and 4.5), establishing the time dependence that represents the sorption of cadmium with a pseudo-second-order kinetic model. It was observed that 4 h is enough to ensure that the equilibrium uptake was reached.
Keywords: Biosorption; Algae; Cadmium; Sargassum muticum; Cross-link; NICCA;
Micellar copolymerization of associative polymers: Study of the effect of acrylamide on sodium dodecyl sulfate–poly(propylene oxide) methacrylate mixed micelles by Guillaume Bastiat; Bruno Grassl; Jeanne François (359-370).
Mixed micelles of sodium dodecyl sulfate (SDS) and poly(propylene oxide) methacrylate (PPOMA) have been studied in the presence of acrylamide using conductimetry, fluorescence spectroscopy, and small-angle neutron scattering (SANS) under the following conditions: (i) the SDS–acrylamide binary system in water; (ii) the SDS–acrylamide–PPOMA ternary system in water. The addition of acrylamide in SDS solutions perturbs the micellization of the surfactant by decreasing the aggregation number of the micelles and increasing their ionization degree. The variations of the various micellar parameters versus the weight ratio R=PPOMA/SDS are different in the presence of acrylamide or in pure water. These differences are much more pronounced for the lower than for the higher PPOMA concentrations. There is competition between acrylamide and PPOMA and at higher PPOMA concentration, acrylamide tends to be released from SDS micelles and is completely replaced by PPOMA.
Keywords: Mixed micelles; Sodium dodecylsulfate; Steady-state fluorescence quenching; Small-angle neutron scattering; Acrylamide; Micellar copolymerization;
Dielectric properties of Bauhinia monandra and Concanavalin A lectin monolayers, part I by Cesar A.S. Andrade; Adam Baszkin; Nereide S. Santos-Magalhães; Luana C.B.B. Coelho; Celso P. de Melo (371-378).
The dielectric properties of the galactose-binding lectins Bauhinia monandra (BmoLL) and Concanavalin A (Con A) were assessed by surface potential measurements of their spread monolayers on an aqueous subphase containing a monovalent electrolyte. For both lectins the curves of surface potential versus mean molecular area (ΔV–A) and the independently recorded isotherms of surface pressure versus mean molecular area (Π–A) were shown to be pH-dependent. As the subphase pH changed from 2 to 9, a noticeable trend to higher surface pressures accompanied the compression of the monolayers. Conversely, the surface potentials values of both monolayers decreased with increasing pH. For Con A, with the single exception of the pH 9 case, lowering the pH yielded ΔV values higher than those for BmoLL. The contribution of the electric double layer ( Ψ 0 ) to the overall ΔV values at a given Π (15 mN/m) was calculated using a modified Davies equation and assuming that at this surface pressure the monolayers of both studied lectins were stable. While at all studied pHs the Ψ 0 values for Con A exceeded those calculated for BmoLL, for both lectins they were insensitive to pH changes. This provided evidence that the reorientation of lectin molecules, during compression predominantly contributed to the alteration of the overall ΔV values. The calculated Ψ 0 values made possible the evaluation of the dipole moments for BmoLL and Con A, and it has been estimated that the decrease in the pH of the subphase from 9 to 2 produced a 1.6-fold (twofold) increase in the value of for BmoLL (Con A). The differences in dielectric properties between the two film-forming lectins have been attributed to the differences in their structures. Indeed, the circular dichroism (CD) spectrum of Con A showed the predominance of β-plated sheet structures while that of BmoLL was typically rich in α-helix structures.
Keywords: Bauhinia monandra; Concanavalin A; Lectins; Monolayers; Surface potential; Dipole moments; Circular dichroism;
Mixed monolayers of Bauhinia monandra and Concanavalin A lectins with phospholipids, part II by Cesar A.S. Andrade; Adam Baszkin; Nereide S. Santos-Magalhães; Luana C.B.B. Coelho; Celso P. de Melo (379-385).
Isotherms of surface pressure and surface potential versus mean molecular area for dibehenoylphosphatidylcholine (DBPC), dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylethanolamine (DPPE), and dioleoylphosphatidylcholine (DOPC) monolayers were shown to be greatly modified when these lipids were cospread with either Bauhinia monandra (BmoLL) or Concanavalin A (Con A) lectins. For the binary films of DBPC, DPPC, and DPPE cospread with each of these two lectins, there was both a displacement of the Π – A and Δ V – A isotherms toward higher molecular areas relative to pure lipids and an increase in the maximum surface potential values relative to the Δ V – A relationships observed for the corresponding single-lectin systems. Both effects can be understood in terms of the occurrence of an explicit interaction between the lipids and the lectins. The plots of the corresponding compressibilities versus molecular areas reveal that, for all lipids but DOPC, the extent of this interaction was always larger for BmoLL than for Con A. The DPPC and DPPE mixed films with BmoLL differed in compressibility. Owing to the small DPPE polar headgroup, the DPPE–BmoLL film was much more incompressible than the DPPC–BmoLL mixed monolayer. However, for the DOPC–BmoLL and DOPC–Con A mixed films there was no evidence that an interaction between the lectins and the lipid took place, a fact attributed to the unsaturated character in the DOPC aliphatic chains, which leads to an expanded Π – A isotherm.
Keywords: Langmuir films; Bauhinia monandra; Concanavalin A; Lectins; Phospholipids;
Fast exopolysaccharide secretion of Pseudomonas aeruginosa on polar polymer surfaces by Santina Carnazza; Cristina Satriano; Salvatore Guglielmino; Giovanni Marletta (386-393).
The influence of the surface chemical structure and related physicochemical properties on the adhesion of P. aeruginosa has been studied for moderately hydrophobic polymers and for hydrophilic surfaces obtained by O2-plasma treatments and 50 keV Ar+ beam irradiation of poly(hydroxymethylsiloxane) and poly(ethyleneterephthalate). The surface chemical structure has been obtained by X-ray photoelectron spectroscopy, the roughness was measured by atomic force microscopy, and the surface free energy was evaluated from contact angle measurements for all the polymer substrates before and after the irradiation treatments. It is shown that a massive and unusually fast secretion of exopolysaccharides onto highly polar surfaces, corresponding to the formation of complex three-dimensional multilayers (i.e., biofilm-like structures), occurs already after 2 h of incubation. It is suggested that such highly polar surfaces can operate either by promoting, by means of a still unknown biomolecular mechanism, an early gene expression process or by mimicking the P. aeruginosa cellular walls.
Keywords: P. aeruginosa adhesion; Surface free energy; Exopolysaccharide secretion; Plasma treatment; Ion beam modification; Poly(hydroxymethylsiloxane); Poly(ethyleneterephthalate);
Solvent-induced lysozyme gels: Rheology, fractal analysis, and sol–gel kinetics by Marcelo A. da Silva; Elizabeth P.G. Arêas (394-401).
In this work, the gelation kinetics and fractal character of lysozyme gel matrices developed in tetramethylurea (TMU)-water media were investigated. Gelation times were determined from the temporal crossover point between the storage, G ′ , and loss, G ″ , moduli, as a function of the binary solvent composition and of protein concentration. The inverse dependence of the upper limit of the linear viscoelastic region ( γ 0 ) on protein concentration indicate that the lysozyme gels belong to the "strong link" kind, a gel category where interparticle links are stronger than intraparticle ones. Lysozyme gel fractal dimensions ( D f ) were determined from the analysis of rheological data according to a scaling theory by Shih et al. [Phys. Rev. A 42 (1990) 4772–4779] and were found to be compatible with a diffusion-limited cluster-aggregation kinetics (DLCA) for lysozyme gels formed at the TMU mass fraction in the binary organic–aqueous solvent, w TMU = 0.9 , and with a reaction-limited cluster aggregation kinetics (RLCA) for w TMU in the 0.6 ⩽ w TMU ⩽ 0.8 range.
Keywords: Gels; Fractals; Lysozyme; Rheology; Tetramethylurea; Protein;
Solvent-induced shape evolution of PVP protected spherical silver nanoparticles into triangular nanoplates and nanorods by T.C. Deivaraj; Neeta L. Lala; Jim Yang Lee (402-409).
The reaction between silver nitrate and poly(N-vinyl-2-pyrrolidone) (PVP) in pyridine at ambient conditions could lead to the formation of spherical nanoparticles or quadrilateral and triangular silver nanoplates, depending on the silver-to-PVP ratio used. It is proposed that the spherical Ag nanoparticles, which were formed early in the reaction, were transformed into nanoplates through an Ostwald ripening process driven by the bridging flocculation of small spherical Ag nanoparticles. This unique and hitherto unreported shape evolution process was carefully followed by a combination of techniques, viz., UV–visible spectroscopy, TEM, and powder X-ray diffraction.
Keywords: Ag nanoparticles; Poly(N-vinyl-2-pyrrolidone) (PVP); Nanoplates; Nanoprisms; Ostwald ripening;
The effect of block copolymer EPE1100 on the colloidal stability of Mg–Al LDH dispersions by Xiaoju Wang; Dejun Sun; Shangying Liu; Rui Wang (410-418).
The adsorption isotherm of block copolymer EPE1100 (polyethylene oxide–polypropylene oxide–polyethylene oxide) on the surfaces of Mg–Al LDH particles was determined through a solution depletion method combined with TOC measurement. X-ray diffraction patterns showed that the adsorption of EPE1100 molecules only occurred on the outer surfaces of LDH particles and they did not intercalate into the galleries between the layers. The adsorption of EPE1100 molecules changed the morphology of the particles. The effect of EPE1100 on the colloidal stability of LDH dispersion was investigated from three aspects: after the freezing–melting cycle, after the shearing rotations, and after the addition of electrolyte. The results indicated that the effect of EPE1100 on the colloidal stability of LDH dispersions was strongly related to the state of copolymer adsorption on LDH particle surfaces. It was inferred that the hydrated repulsive force and steric-repulsive force played important roles in determining the stability of the dispersions.
Keywords: Layered double hydroxides; Block copolymer; Colloidal stability; Adsorption;
Preparation and colloidal stability of monodisperse magnetic polymer particles by Shunchao Gu; Junya Onishi; Yoshio Kobayashi; Daisuke Nagao; Mikio Konno (419-426).
A previously proposed method was examined for producing monodisperse, submicrometer-sized magnetic polymer particles. The method applies soap-free emulsion polymerization during which Fe3O4 magnetic nanoparticles are heterocoagulated onto precipitated polymer nuclei. To chemically fix the magnetic particles to the polymer nuclei, vinyl groups were introduced on the Fe3O4 particles in a preliminary surface modification reaction with methacryloxypropyltrimethoxysilane, and methacryloxypropyldimethoxysilane (MPDMS) was added to reaction systems of the soap-free emulsion polymerization. The colloidal dispersion stability of magnetic polymer particles was improved by the addition of an ionic monomer, sodium p-styrenesulfonate (NaSS), during the polymerization. The polymerizations were carried out with styrene monomer and potassium persulfate initiator in ranges of NaSS concentrations ( 0 – 2.4 × 10 −3 M ), NaSS addition times (60–80 min), and monomer concentrations (0.3–0.6 M) at fixed concentrations of 1.6 × 10 −2 M initiator and 1.3 × 10 −2 M MPDMS for pH 4.5 adjusted with a buffer system of [CH3COOH]/[NaOH]. The addition of NaSS during the polymerization could maintain the dispersion stability of magnetic polymer particles during the polymerization. Selection of the reaction conditions enabled the preparation of colloidally stable, submicrometer-sized magnetic polymer particles that had coefficients of variation of distribution smaller than the standard criterion for monodispersity, 10%.
Keywords: Magnetic polymer particle; Polystyrene; Soap-free emulsion polymerization; Ionic monomer; Heterocoagulation; Colloidal dispersion stability;
Morphology and surface properties of fumed silicas by V.M. Gun'ko; I.F. Mironyuk; V.I. Zarko; E.F. Voronin; V.V. Turov; E.M. Pakhlov; E.V. Goncharuk; Y.M. Nychiporuk; N.N. Vlasova; P.P. Gorbik; O.A. Mishchuk; A.A. Chuiko; T.V. Kulik; B.B. Palyanytsya; S.V. Pakhovchishin; J. Skubiszewska-Zięba; W. Janusz; A.V. Turov; R. Leboda (427-445).
Several series of fumed silicas and mixed fumed oxides produced and treated under different conditions were studied in gaseous and liquid media using nitrogen and water adsorption–desorption, mass spectrometry, FTIR, NMR, thermally stimulated depolarization current (TSDC), photon correlation spectroscopy (PCS), zeta potential, potentiometric titration, and Auger electron spectroscopy methods. Aggregation of primary particles and adsorption capacity (V p) decrease and hysteresis loops of nitrogen adsorption–desorption isotherms becomes shorter with decreasing specific surface area (S BET). However, the shape of nitrogen adsorption–desorption isotherms can be assigned to the same type independent of S BET value. The main maximum of pore size distribution (gaps between primary nonporous particles in aggregates and agglomerates) shifts toward larger pore size and its intensity decreases with decreasing S BET value. The water adsorption increases with increasing S BET value; however, the opposite effect is observed for the content of surface hydroxyls (in mmol/m2). Associative desorption of water (2(Si―OH) → Si―O―Si + H2O) depends on both the morphology and synthesis conditions of fumed silica. The silica dissolution rate increases with increasing S BET and pH values. However, surface charge density and the modulus of zeta-potential increase with decreasing S BET value. The PCS, 1H NMR, and TSDC spectra demonstrate rearrangement of the fumed silica dispersion depending on the S BET value and the silica concentration (C SiO2 ) in the aqueous suspensions. A specific state of the dispersion is observed at the C SiO 2 values corresponding to the bulk density of the initial silica powder.
Keywords: Fumed silica; Morphology; Structural and adsorption characteristics; Synthesis; Interfacial water; Nonfreezable water; 1H NMR; TSDC; Concentrated aqueous suspension; Particle size distribution; Zeta potential; FTIR; Surface charge density; Dissolution of oxides; Water desorption;
An electrochemical quartz crystal impedance study on anti-human immunoglobulin G immobilization in the polymer grown during dopamine oxidation at an Au electrode by Hua He; Qingji Xie; Shouzhuo Yao (446-454).
The polymeric film grown during dopamine oxidation at an Au electrode was studied as a novel matrix for immobilizing anti-human immunoglobulin G (IgG) via the electrochemical quartz crystal impedance analysis (EQCIA) method. The growth of the polymeric films at Au electrodes during dopamine oxidation in neutral phosphate buffer (pH 7.4) and the immobilization of anti-human IgG into the polymeric films during their growth have been traced at real time. Lysozyme control experiments suggested that anti-human IgG was electrostatically incorporated into the polymeric film. Also, the porosity of the polymeric films has been discussed by measuring the "wet" and "dry" frequency shifts. Compared with a polypyrrole film immobilized with anti-human IgG, the proposed matrix possessed a larger amount of specific binding sites for human IgG by subsequent immunoreaction tests. The association constant of the anti-human IgG immunoreaction was obtained with satisfactory results.
Keywords: Electrochemical quartz crystal impedance analysis; Polymerization during dopamine oxidation; Immobilization of anti-human IgG; Human IgG; Au electrode;
Free radical generation upon plasma treatment of cotton fibers and their initiation efficiency in surface-graft polymerization by Laura Andreozzi; Valter Castelvetro; Gianluca Ciardelli; Leopoldo Corsi; Massimo Faetti; Enrico Fatarella; Fabio Zulli (455-465).
Low-temperature plasma was used to activate mercerized cotton fabrics, to be followed by grafting with various methacrylates. Careful analysis of the experimental electron spin resonance (ESR) lineshapes of cotton samples treated at different RF powers made it possible to recognize and quantify four different species of free radicals still persistent 30 h after irradiation in the samples maintained under inert atmosphere. The decay rate of these species at room temperature was also evaluated with the analysis of the time evolution of the ESR spectra. The nature of the free radical species actually involved in the monomer grafting reaction has been discussed for cotton fabrics prepared under different plasma treatment conditions by analyzing the ESR lineshapes.
Keywords: ESR; Fibers; Irradiation; Plasma grafting; Free radicals;
Vanadia-catalyzed solar photooxidation of aniline by Chockalingam Karunakaran; Sambandam Senthilvelan (466-471).
Vanadia photocatalyzes the oxidation of aniline to azobenzene in ethanol. The reaction was studied using natural sunlight and UV irradiation (365 nm) as a function of [aniline], catalyst loading, airflow rate, solvent composition, etc. The photocatalyst exhibits sustainable catalytic activity. The product formation is greater with illumination at 254 nm than at 365 nm. Electron donors such as triphenylphosphine, diphenylamine, and hydroquinone enhance the photocatalysis. The singlet oxygen quencher azide ion fails to inhibit the catalysis. The photocatalysis takes place in both protic and aprotic solvents. The mechanism of photocatalysis is discussed and the product formation analyzed using a kinetic model.
Keywords: Photooxidation; Aniline; Sunlight; UV light; V2O5;
Self-assembly prismatic aggregates formed during the calcination of ZnO powders: In situ monitoring by ETA technique and their photocatalytic properties by D. Li; V. Balek; N. Ohashi; T. Mitsuhashi; S. Hishita; H. Haneda (472-478).
This paper describes a unique phenomenon occurred during the calcination of ZnO powders, i.e., the ZnO particles self-assembled to form prismatic aggregates with a clear edges and faces. Field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used to characterize the particle morphology and crystal structure of the calcined sample. The emanation thermal analysis (ETA) technique was used to monitor the changes of ZnO particle surface and subsurface microstructure irregularities and the occurrence of interparticle compaction phenomena under in situ conditions of heating and cooling. It was assumed from the ETA results that the driven force of the self-assembly of ZnO particles towards prismatic aggregates originated from the solid state diffusion and migration of grain boundaries. The photocatalytic tests indicated that the prismatic aggregates of ZnO calcined at 800 °C demonstrated a highest photocatalytic activity for acetaldehyde decomposition because of the enhancement of the surface-exposed high-active crystal face of ( 10 1 ¯ 0 ).
Keywords: Zinc oxide; Self-assembly; Emanation thermal analysis; Photocatalysis;
Influence of various monovalent cations and calcium ion on the colloidal fouling potential by Lianfa Song; Gurdev Singh (479-487).
The influence of various monovalent cations and of divalent calcium ions on colloidal fouling strength was investigated quantitatively on a bench-scale ultrafiltration device. A higher colloidal fouling potential (k) was consistently observed with lithium chloride compared to the same ionic strengths of chlorides of other monovalent cations (Na+, K+, and Cs+). This observation was attributed to the formation of an impervious layer around the colloidal particle by lithium ions that prevented the repulsive forces due to the interaction of the silica hairs formed on the particles in the presence of water. The impact of the divalent calcium ion on the fouling potential was more complex. The fouling potential first increased with calcium ion concentration and then decreased. The maximum value of fouling potential occurred at the ionic strength corresponding to the critical coagulation concentration, which decreased with increasing colloid concentration. The colloidal fouling potential was well correlated by a bilinear relationship with colloid concentration and ionic strength for all salts tested under the critical coagulation concentration.
Keywords: Fouling potential; Ionic strength; Valence; Aggregation; Colloid concentration; Critical coagulation concentration; Quantitative;
Self-assembling structures and thin-film microscopic morphologies of amphiphilic rod–coil block oligomers by Hongbo Li; Qingtao Liu; Lidong Qin; Miao Xu; Xiankun Lin; Shengyan Yin; Lixin Wu; Zhongmin Su; Jiacong Shen (488-497).
This paper examines the influences of solvent evaporation and atmosphere humidity on self-assembling structures and thin-film microscopic morphologies of amphiphilic rod–coil block oligomers (EO n OPV) containing conjugated oligo(phenylene vinylene) dimer (OPV) coupled to poly(ethylene oxide) (PEO; n, the average number of ethylene oxides, is 16, 12, 7, and 3, respectively) on hydrophilic substrates. Atomic force microscopy (AFM), UV–vis absorption, and small angle X-ray diffraction are employed to investigate the thin-film morphology and structure. Solvent evaporation and atmosphere humidity are found to exert a strong influence on thin-film morphology and structure. Under the condition of quick evaporation and dry atmosphere, all EO n OPV oligomers form the monolayer islands. Increasing the solute volume, both EO16OPV and EO12OPV oligomers can form the polar lamellas with a head-to-tail packing arrangement. Under the condition of slow evaporation and humid atmosphere, EO16OPV and EO12OPV may self-assembly into curvy nanoribbons with well-defined width and curvature radii on mica, while EO7OPV and EO3OPV with the shorter PEO coils do not form. A symmetric bilayer structure for the ribbons is proposed. Plausible reasons for the variation in thin-film morphology are discussed, based on the results obtained from investigation of PEO coil length, solvent evaporation, and atmosphere humidity effects.
Keywords: AFM image; Humidity; Rod–coil block oligomer; Solvent evaporation; Self-assembling structure; Thin-film microscopic morphology;
Hydrogen ion titration of alkyldimethylamine oxides by 13C and 1H NMR and conventional methods by Rie Kakehashi; Motohiro Shizuma; Shingo Yamamura; Hiroshi Maeda (498-503).
In the hydrogen ion titration of micelles, the degree of ionization of the micelle at a given pH has to be evaluated to obtain a p K a value of micelles ( K a being the proton dissociation constant) at the pH. We compared the degree of ionization obtained from 13C and 1H NMR spectra with that obtained from the stoichiometric method. We used dodecyldimethylamine oxide (C12DMAO) and hexyldimethylamine oxide (C6DMAO) to examine the titration behavior of micelles and monomers, respectively. We determined p K a values of amine oxides both in H2O and D2O. As to the monomer (C6DMAO), the degree of ionization from NMR, α NMR, coincided with that from the conventional stoichiometric method α. The difference of p K 1 of amine oxide monomer between D2O and H2O was about 0.5: pK 1(D) ≈ pK 1(H) + 0.5. The difference was about the same as that for carboxylic acids. As to the C12DMAO micelle, α NMR did not coincide with α over a considerable range of α. The NMR chemical shift might be influenced by micellar structure changes induced by the ionization, such as the sphere-to-rod transition. The intrinsic logarithmic dissociation constants of the micelle were 5.9 ± 0.1 for H2O, and 6.5 ± 0.1 for D2O.
Keywords: Hydrogen ion titration; Mixed micelles; Amine oxides; NMR titration; Degree of ionization of micelles; Dissociation constant in D2O;
Preparation and characterization of new hybrid organic/inorganic systems derived from calcium (α-aminoalkyl)-phosphonates and -phosphonocarboxylates by Fatima Al-Ali; Albert Lebugle; Isabelle Rico-Lattes; Guita Etemad-Moghadam (504-511).
We have studied the phenomenon of calcium complexation by lab synthesized amphiphilic (α-aminoalkyl)-phosphonocarboxylic or -phosphonic acids. The electrical conductivity of aqueous solutions of sodium salts of all these acids was measured versus the volume of a calcium salt solution added. It appeared that calcium complexes are formed in a Ca/P atomic ratio close to 1. Calcium phosphonocarboxylates and calcium phosphonates were also precipitated by mixing aqueous solutions of disodium salts of phosphorus amphiphiles and calcium nitrate solutions. Before chemical analysis, these complexes were calcined to remove the organic part. In the mineralized products, calcium and phosphate were assayed: the Ca/P atomic ratio was equal to 1. X-ray diffraction and IR spectroscopy showed that they are made entirely of β pyrophosphate (Ca2P2O7), a result in agreement with previous chemical analysis. The chemical formula of the starting calcium complexes could be written as CaL⋅2H2O (L = ligand). The SEM micrographs of these complexes show plate-like structures. XRD patterns are characteristic of layered structures. These facts suggest that calcium complexes are composed of alternating bimolecular layers of calcium alkylphosphonocarboxylates or calcium alkylphosphonates, the chains being tilted and partially interdigitated.
Keywords: Calcium (α-aminoalkyl)-phosphonates; Calcium (α-aminoalkyl)-phosphonocarboxylates; Conductimetric study; Layered structures;
The importance of lipophobicity in surfactants: Methods for measuring lipophobicity and its effect on the properties of two types of nonionic surfactant by Morinobu Fukuda (512-520).
In researching the properties of surfactants, lipophobicity is an important consideration. Increasing surfactant lipophobicity corresponds to a decrease in the saturation concentration of a singly dispersed surfactant in oil, i.e., a decrease in the critical micelle concentration in oil (CMC(oil)). This, in turn, is the crucial property in discussing the efficiency of a surfactant. Lipophobicity is influenced by the structure and length of the hydrophilic moiety of the surfactant. Surfactants that consist of ―OH or C=O groups are effective for use in both aliphatic and aromatic hydrocarbon-rich systems because they are highly lipophobic and of a compact size and function independent of temperature. These characteristics are also reflected in their phase behavior. Phase diagrams illustrate the following properties: temperature independence; strong absorption at the water–oil interface and efficient action even with a very small amount of surfactant with a low CMC; high solubilization of water and oil into an aggregated surfactant solution phase. Through phase diagrams, the CMC(oil) of R10EO8 was obtained and the result used to compare the many different characteristics of the more typical oxyethylene nonionic surfactants with the new polyglyceryl nonionic surfactants.
Keywords: Lipophobicity; Glyceryl nonionic surfactant; Polyoxyethylene nonionic surfactant; Amphiphobicity; Aromatic hydrocarbon; HLB temperature;
Mixed micelles of alkylamines and cetyltrimethylammonium chloride by L. García-Río; J.R. Leis; J.L. López-Fontán; J.C. Mejuto; V. Mosquera; P. Rodríguez-Dafonte (521-529).
The influence of chain length and the nature of the head group on the composition of micelles of a binary mixture of cetyltrimethylammonium chloride with both unsubstituted and N-substituted n-octyl, n-decyl, and n-lauryl amines was established from the variation of the critical micelle concentration (cmc) as a function of the solution composition. A synergistic effect was observed in all instances that were found to be correlated with chain length and the type of N-substituent on the alkylamine head group. Experimental data were compared with theoretical predictions based on the equilibrium between micelles and monomers in solution. The Motomura treatment was used to determine the composition of each compound in the mixed micelles ( X ¯ i m ). Mixing nonideality was expressed in terms of the molecular interaction parameter ( β 12 ) as determined using the theory of Holland and Rubingh. Finally, the molecular thermodynamic model for mixed surfactant systems developed by Puvvada and Blankschtein was used to estimate the micellization free energy ( Δ G M ) and to evaluate the synergistic phenomenon.
Keywords: Mixed micelle; cmc; Amine; Micellization energy;
Physicochemical studies on microemulsions by Indranil Chakraborty; Satya P. Moulik (530-541).
Both volume- and temperature-induced percolation of conductance of w/o microemulsions formed with AOT in cyclic aliphatic and aromatic oils (cyclohexane, cyclohexanone, toluene, and xylenes), and volume percolation of water/AOT/oil systems using linear aliphatic hydrocarbons (n-hexane, n-heptane, n-octane, i-octane, and n-decane) have been studied. The effect of additives, viz. sodium cholate (NaC), sodium deoxycholate (NaDC), cholesterol, n-butanol, and t-butanol, toluene, and xylenes (o, m, and p) on the temperature-induced percolating processes using the oils cyclohexane and cyclohexanone has been examined. The percolation results have been analyzed in the light of scaling equation, and the energy of activation of the ion-transport phenomenon has been evaluated for both pre- and postpercolation stages. From the percolation data, the diameter of the microdispersed water droplets, their population, and surface area have been estimated. The enthalpy of dispersion of water in AOT/oil medium has been determined from isothermal titration calorimetric (ITC) measurements.
Keywords: Volume and temperature percolation; Cyclic and aliphatic hydrocarbon oils; AOT; Thermodynamics; Microcalorimetry;
Surface modification of liposomes by saccharides: Vesicle size and stability of lactosyl liposomes studied by photon correlation spectroscopy by Junmin Zhu; Feng Yan; Zhongwu Guo; Roger E. Marchant (542-550).
The cell glycocalyx is an attractive model for surface modification of liposomes, because its hydrated oligosaccharide layer inhibits nonspecific protein adsorption and can provide specificity towards desired sites. Here, we report on the use of lactose as a model saccharide to modify the liposome surface and examine the vesicle size and stability. Two kinds of lactosyl lipids, including lactosyl ether-lipid (6a) and lactosyl ester-lipid (6b), which contain octadecyl and octadecanoyl as the lipid tails, respectively, were synthesized and their liposomes were prepared by the extrusion method. The effects of glycolipid structure, concentration, and the pore size of the extrusion membrane on vesicle size and stability were investigated at room temperature by photon correlation spectroscopy (PCS). All liposomes with 5 or 10 mol% of lactosyl lipids had a narrow size distribution and remained stable at room temperature for at least one month, which is comparable to 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)- and poly(ethylene glycol) (PEG)-liposomes. The maximum incorporation of lactosyl ester-lipid into liposomes was 15 mol%, compared with only 10 mol% for the lactosyl ether-lipid. The lactosyl ester-liposomes had better stability and exhibited less size change than the lactosyl ether-liposomes at 15 or 20 mol% of lactosyl lipids incorporated. This may be attributed to the better structural compatibility of lactosyl ester-lipid with DSPC. The PCS results show that the glycolipid structure and concentrations are major factors that affect vesicle stability, while the pore size of extrusion membranes has no influence.
Keywords: Liposomes; Lactose; Glycolipids; Surface modification; Cell glycocalyx;
Mixed micelles of series of monomeric and dimeric cationic, zwitterionic, and unequal twin-tail cationic surfactants with sugar surfactants: A fluorescence study by Mandeep Singh Bakshi; Gurpreet Kaur (551-559).
Steady state fluorescence measurements have been carried out for binary mixtures of a series of monomeric cationic (MC), zwitterionic (ZI), dimeric cationic (DC), and twin-tail cationic (TC) surfactants with sugar (β-C8G and β-C12G) over the whole mole fraction range using pyrene as fluorescence probe. The cmc values thus determined for all the binary mixtures have been further evaluated using the regular solution theory. The various micellar parameters, such as micelle mole fraction ( X 1 ), regular solution interaction parameter (β), micropolarity, and mean micelle aggregation number (N agg), have been determined for all these series of mixtures. Variation in all these micellar parameters demonstrates that mixed micelles of these surfactants with β-C8G are mostly synergistic in nature and the synergism increases with the increase in hydrophobicity of the cosurfactant in each case. The mixtures of β-C12G with various cosurfactants do not show this behavior and instead of it, they show an increase in antagonism with the increase in hydrophobicity of cosurfactants. This discrepancy has been attributed to a large difference in hydrophobicity between β-C8G and β-C12G, and the chain folding of the latter is considered to be the reason for the antagonism.
Keywords: Mixed micelles; Sugar surfactants; Cationic surfactants; Fluorescence studies; Synergism;
Area per surfactant molecule values of gemini surfactants at the liquid–hydrophobic solid interface by Martin Pisárčik; Milton J. Rosen; Mária Polakovičová; Ferdinand Devínsky; Ivan Lacko (560-565).
Areas per surfactant molecule at the liquid/hydrophobic solid ( A LS ) and the liquid/air ( A LA ) interface as a function of the spacer length are reported for cationic gemini surfactants having ―(CH2) n ― spacer s. A LA increases with increasing spacer length up to 6–8 ―CH2 ― groups in the spacer and then levels off. A LS values indicate a more closely packed arrangement of the surfactant molecules than that at the liquid/air interface. Comparison of A LA and A LS values indicates that the surfactant molecules at the liquid/hydrophobic solid interface are almost three times as closely packed as those at the liquid/air interface. A comparison of the experimental values of the area per surfactant molecule at both interfaces was made with those calculated from dimensions of the surfactant molecule in vacuo.
Keywords: Gemini surfactant; Surfactant spacer; Area per surfactant molecule; Surface tension;
Surfactant tail length-dependent lipase activity profile in cationic water-in-oil microemulsions by Antara Dasgupta; Debapratim Das; Rajendra Narayan Mitra; Prasanta Kumar Das (566-573).
The catalytic activity of Chromobacterium viscosum lipase (CV-lipase) was estimated across varying surfactant tail lengths (C-10–C-18) in water-in-oil (w/o) microemulsions of cationic surfactants containing four different hydroxyethyl-substituted head groups. An attempt to find a correlation, if any, between the activity of interfacially solubilized lipase and the varying surfactant tails was made for the first time in micellar enzymology. The second-order rate constant, k 2 , in lipase-catalyzed hydrolysis of p-nitrophenyl-n-hexanoate at pH 6.0 and 25 °C shows an improvement in enzyme activity (∼30–140%) across different head groups of amphiphiles with increasing tail lengths in varying solution compositions. Improvement of enzyme activity is prominent in ascending from C-10 to C-14/C-16, depending on the nature of polar head group. The hydrolytic activity of lipase in different surfactant (50 mM)/water/isooctane/n-hexanol with varying z= [alcohol]/[surfactant] (6.4 or 4.8) was amplified by 25–250% with increment in surfactant tail length in comparison with widely used cationic w/o microemulsions having solution compositions ( z = 16 ) . As a notable outcome of this research, we found w/o microemulsions of 25 mM tetradecyltrimethylammonium bromide/water/isooctane/n-hexanol ( z = 8 ) producing the highest ever activity of lipase in any w/o microemulsions.
Keywords: Amphiphiles; Enzymes; Packing parameter; Reverse micelles; Surfactant tail;
Example of an organic reaction in a Langmuir film: Reduction of an amphiphilic ketone by NaBH4 by Ignacio Gascon; Cosmin Patrascu; Jean-Daniel Marty; Christophe Mingotaud (574-580).
Langmuir monolayers of an amphiphilic ketone 1 have been studied on pure water and on aqueous subphases containing sodium borohydride. Changes in the compression isotherm and in the monolayer morphology were observed when the concentration of NaBH4 or the delay between spreading and compression was increased. These modifications were specific to NaBH4 and suggested that a chemical reaction is taking place along the monolayer. Modifications in the IR spectrum of the corresponding Langmuir–Blodgett film confirmed the reduction of the ketone group of 1 when spread on aqueous subphases of sodium borohydride. Analysis of the compression isotherms demonstrated that this reaction occurred for all surface pressures and therefore indicated that the ketone group of 1 is accessible to the borohydride whatever the compression state of the monolayer.
Keywords: Langmuir film; Chemical reaction; Reduction; Brewster angle microscopy; Transition;
Adsorption and micellar properties of a mixed system of nonionic–nonionic surfactants by Md. Nazrul Islam; Teiji Kato (581-587).
We study the surface adsorption and bulk micellization of a mixed system of two nonionic surfactants, namely, ethylene glycol mono-n-dodecyl ether (C12E1) and tetraethylene glycol mono-n-tetradecyl ether (C14E4), at different mixing ratios at 15 °C. The pure C14E4 monolayer cannot show any indicative features of phase transition because of both hydration-induced and dipolar repulsive interactions between the bulky head groups. On the other hand, the monolayers of pure C12E1 and its mixture with C14E4 undergo a first-order phase transition, showing a variety of surface patterns in the coexistence region between the liquid expanded (LE) and liquid condensed (LC) phases under the same experimental conditions. For pure C12E1, the domains are of a fingering pattern while those for the C12E1/C14E4 mixed system are found to be compact circular and small irregular structures at 2:1 and 1:1 molar ratios, respectively. The critical micelle concentration (cmc) values of both the pure and the mixed systems were measured to understand the micellar behavior of the surfactants in the mixture. The cmc values of the mixed system were also calculated assuming ideal behavior of the surfactants in the mixture. The experimental and calculated values are found to be very close to each other, suggesting an almost ideal nature of mixing. The interaction parameters for mixed monolayer and micelle formation were calculated to understand the mutual behavior of the surfactants in the mixture. It is observed that the interaction parameters for mixed monolayer formation are more negative than those of micelle formation, indicating a stronger interaction between the surfactants during monolayer formation. It is concluded that since both the surfactants bear EO units in their head groups, structural parity and hydrogen bonding between the surfactants allow them to be closely packed during monolayer and micelle formation.
Keywords: Brewster angle microscopy; Monoionic surfactants; Adsorbed monolayers; Critical micelle concentration;
Single-crystalline CuO nanobelts fabricated by a convenient route by Xinyu Song; Haiyun Yu; Sixiu Sun (588-591).
A reverse micelle-assisted route for preparing CuO nanobelts from precursor Cu(OH)2− 4 is reported. The reverse micelles were used as microreactors, which led to anisotropic growth crystals during a simple solvothermal process. The formation conditions of the CuO nanobelts were also studied.
Keywords: CuO nanobelts; The reverse micelles; Solvothermal process;
Electrokinetic and adsorption studies of alumina suspensions using Darvan C as dispersant by Bimal P. Singh; Sarama Bhattacharjee; Laxmidhar Besra; D.K. Sengupta (592-596).
The electrokinetic and adsorption characteristics of alumina suspensions in the presence of Darvan C as dispersant have been investigated. The interaction of Darvan C with alumina has been interpreted in terms of electrokinetic and adsorption measurements. The adsorption density of Darvan C increases greatly with decreasing pH. The isoelectric point (iep) of the sample under investigation is found to be located at pH 9.1. For pH values near and below the point of zero charge, there is an added electrostatic attractive potential for adsorption, which results in high-affinity adsorption behavior. Possible mechanisms of interaction between alumina and Darvan C are described and discussed.
Keywords: Dispersion; Surface charge; Alumina; Adsorption; Electrokinetics; Dispersant;
Pioneer studies on HCl and silylation treatments of chrysotile by Efrain Mendelovici; Ray L. Frost (597-599).
In the light of some recent studies on organosilicon derivatives of HCl-leached chrysotile, pioneer works not cited in this area are chronologically and briefly commented on, emphasizing the infrared spectroscopy (FTIR–PAS) characterization of such chrysotile products. The latter have opened a far-reaching potential for the development of, e.g., highly stable hydrophobic or organophilic materials, including fibrous sheet polymers.
Keywords: Chrysotile; HCl and silylation treatments; FTIR–PAS;
Dispersion of components in transport processes: Velocity dispersion model by S. Pivovarov (600-603).
This paper presents a new model of dispersion of components in transport processes. It is suggested that the flow velocity may be specified by a Gauss function with relative dispersion of flow velocity β = σ v / v ; the overall dispersion of inert component (in porous as well as in homogeneous medium) may be calculated from the equation σ = ( 2 D t / τ 2 + ( β v t ) 2 ) 0.5 , where D is the diffusion coefficient, t is time, τ is tortuosity, and v is flow velocity. The most common range of variability of relative dispersion of flow velocity in natural soils is 8–32%. The model is well applicable to column and field experiments.
Keywords: Transport phenomena; Porous media; Diffusion; Dispersion; Dispersivity; Porosity; Tortuosity; Gauss function;
by Arthur Hubbard (604).
Corrigendum to "Book review: Fernando Wypych, Kestur Gundappa Satyanarayana (Eds.), Clay Surfaces: Fundamentals and Applications, Elsevier, Amsterdam, 2004, 553 pp." [J. Colloid Interface Sci. 283 (2005) 619] by Arthur Hubbard (605).
Author Index for Volume 289 (606-607).