High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify specific components in mixtures. The mixtures can originated from food, chemicals, pharmaceuticals, biological, environmental and agriculture, etc, which have been dissolved into liquid solutions.  It relies on high pressure pumps, which deliver mixtures of various solvents, called the mobile phase, which flows through the system, collecting the sample mixture on the way, delivering it into a cylinder, called the column, filled with solid particles, made of adsorbent material, called the stationary phase. Each component in the sample interacts slightly different with the adsorbent material, causing different migration rate for the each component, leading to their separation, as they flow out of the column into a specific detector. The output of the detector is a graph, called Chromatogram.  Chromatograms are graphical representations of the signal intensity versus time or volume, showing peaks, which represent components of the sample, each appears in its respective time, called Retention Time, having area proportional to its amount.

HPLC is widely used for manufacturing (e.g., during the production process of pharmaceutical and biological products), legal (e.g., detecting performance enhancement drugs in urine), research (e.g., separating the components of a complex biological sample, or of similar synthetic chemicals from each other), and medical (e.g., detecting vitamin D levels in blood serum) purposes.

Chromatography can be described as a mass transfer process involving adsorption and/or partition.  As mentioned, HPLC relies on pumps to pass a pressurized liquid and a sample mixture through a column filled with adsorbent, leading to the separation of the sample components. The active component of the column, the adsorbent, is typically a granular material made of solid particles (e.g., silica, polymers, etc.), 1.5–50 μm in size, on which various reagents can be bonded.  The components of the sample mixture are separated from each other due to their different degrees of interaction with the adsorbent particles.  The pressurized liquid is typically a mixture of solvents (e.g., water, buffers, acetonitrile and/or methanol) and is referred to as a "mobile phase".  Its composition and temperature play a major role in the separation process by influencing the interactions taking place between sample components and adsorbent. These interactions are physical in nature, such as hydrophobic (dispersive), dipole–dipole and ionic, most often a combination.

Operation
The liquid chromatograph is complex and has sophisticated and delicate technology. In order to properly operate the system. It is also desirable that there should be a minimum basis for understanding of how the device performs the data Processing to avoid incorrect data and distorted results

HPLC is distinguished from traditional ("low pressure") liquid chromatography because operational pressures are significantly higher (50–~1400 bar), while ordinary liquid chromatography typically relies on the force of gravity to pass the mobile phase through the packed column. Due to the small sample amount separated in analytical HPLC, typical column dimensions are 2.1–4.6 mm diameter, and 30–250 mm length.  Also HPLC columns are made with smaller adsorbent particles (1.5–50 μm in average particle size).  This gives HPLC superior resolving power (the ability to distinguish between compounds) when separating mixtures, which makes it a popular chromatographic technique.

The schematic of an HPLC instrument typically includes solvents' reservoirs, one or more pumps, a solvent-degasser, a sampler, a column, and a detector. The solvents are prepared in advance according to the needs of the separation, they pass through the degasser to remove dissolved gasses, mixed to become the mobile phase, then flow through the sampler, which brings the sample mixture into the mobile phase stream, which then carries it into the column.  The pumps deliver the desired flow and composition of the mobile phase through the stationary phase inside the column, then directly into a flow-cell inside the detector.  The detector generates a signal proportional to the amount of sample component emerging from the column, hence allowing for quantitative analysis of the sample components.  The detector also marks the time of emergence, the Retention Time, which serves for initial identification of the component. More advanced detectors, provide also additional information, specific to the analyte's characteristics, such as UV-VIS spectrum or Mass spectrum, which can provide insight on its structural features. These detectors are in common use, such as UV/Vis, Photodiode array (PDA) / diode array detector and mass spectrometry detector.

A digital microprocessor and user software control the HPLC instrument and provide data analysis. Some models of mechanical pumps in an HPLC instrument can mix multiple solvents together at a ratios changing in time, generating a composition gradient in the mobile phase.  Most HPLC instruments also have a column oven that allows for adjusting the temperature at which the separation is performed.

The sample mixture to be separated and analyzed is introduced, in a discrete small volume (typically microliters), into the stream of mobile phase percolating through the column. The components of the sample move through the colum, each at a different velocity, which are a function of specific physical interactions with the adsorbent, the stationary phase. The velocity of each component depends on its chemical nature, on the nature of the stationary phase (inside the column) and on the composition of the mobile phase. The time at which a specific analyte elutes (emerges from the column) is called its retention time. The retention time, measured under particular conditions, is an identifying characteristic of a given analyte.

Many different types of columns are available, filled with adsorbents varying in particle size, porosity, and surface chemistry. The use of smaller particle size packing materials requires the use of higher operational pressure ("backpressure") and typically improves chromatographic resolution (the degree of peak separation between consecutive analytes emerging from the column). Sorbent particles may be ionic, hydrophobic or polar in nature.

The most common mode of liquid chromatography is Reversed Phase, whereby the mobile phases used, include any miscible combination of water or buffers with various organic solvents (the most common are acetonitrile and methanol). Some HPLC techniques use water-free mobile phases (see normal-phase chromatography below). The aqueous component of the mobile phase may contain acids (such as formic, phosphoric or trifluoroacetic acid) or salts to assist in the separation of the sample components. The composition of the mobile phase may be kept constant ("isocratic elution mode") or varied ("gradient elution mode") during the chromatographic analysis. Isocratic elution is typically effective in the separation of simple mixtures. Gradient elution is required for complex mixtures, with varying interactions with the stationary and mobile phases. This is the reason why in gradient elution the composition of the mobile phase is varied typically from low to high eluting strength.  The eluting strength of the mobile phase is reflected by analyte retention times, as the high eluting strength speeds up the elution (resulting in shortening of retention times). For example, a typical gradient profile in reversed phase chromatography for might start at 5% acetonitrile (in water or aqueous buffer) and progress linearly to 95% acetonitrile over 5–25 minutes. Periods of constant mobile phase composition (plateau) may be also part of a gradient profile. For example, the mobile phase composition may be kept constant at 5% acetonitrile for 1–3 min, followed by a linear change up to 95% acetonitrile.

The chosen composition of the mobile phase depends on the intensity of interactions between various sample components ("analytes") and stationary phase (e.g., hydrophobic interactions in reversed-phase HPLC). Depending on their affinity for the stationary and mobile phases, analytes partition between the two during the separation process taking place in the column. This partitioning process is similar to that which occurs during a liquid–liquid extraction but is continuous, not step-wise.

In the example using a water/acetonitrile gradient, the more hydrophobic components will elute (come off the column) later, then, once the mobile phase gets richer in acetonitrile (i.e., in a mobile phase becomes higher eluting solution), their elution speeds up.

The choice of mobile phase components, additives (such as salts or acids) and gradient conditions depends on the nature of the column and sample components. Often a series of trial runs is performed with the sample in order to find the HPLC method which gives adequate separation.

History and development

Prior to HPLC, scientists used benchtop column liquid chromatographic techniques. Liquid chromatographic systems were largely inefficient due to the flow rate of solvents being dependent on gravity. Separations took many hours, and sometimes days to complete. Gas chromatography (GC) at the time was more powerful than liquid chromatography (LC), however, it was obvious that gas phase separation and analysis of very polar high molecular weight biopolymers was impossible. GC was ineffective for many life science and health applications for biomolecules, because of they are mostly non-volatile and thermally unstable at the high temperatures of GC. As a result, alternative methods were hypothesized which would soon result in the development of HPLC.

Following on the seminal work of Martin and Synge in 1941, it was predicted by Calvin Giddings, Josef Huber, and others in the 1960s that LC could be operated in the high-efficiency mode by reducing the packing-particle diameter substantially below the typical LC (and GC) level of 150 μm and using pressure to increase the mobile phase velocity. These predictions underwent extensive experimentation and refinement throughout the 60s into the 70s until these very days. Early developmental research began to improve LC particles, for example the historic Zipax, a superficially porous particle.

The 1970s brought about many developments in hardware and instrumentation. Researchers began using pumps and injectors to make a rudimentary design of an HPLC system. Gas amplifier pumps were ideal because they operated at constant pressure and did not require leak-free seals or check valves for steady flow and good quantitation. Hardware milestones were made at Dupont IPD (Industrial Polymers Division) such as a low-dwell-volume gradient device being utilized as well as replacing the septum injector with a loop injection valve.

While instrumentation developments were important, the history of HPLC is primarily about the history and evolution of particle technology.  After the introduction of porous layer particles, there has been a steady trend to reduced particle size to improve efficiency. However, by decreasing particle size, new problems arose. The practical disadvantages stem from the excessive pressure drop needed to force mobile fluid through the column and the difficulty of preparing a uniform packing of extremely fine materials. Every time particle size is reduced significantly, another round of instrument development usually must occur to handle the pressure.

Types

Partition chromatography

Partition chromatography was one of the first kinds of chromatography that chemists developed, and is barely used these days. The partition coefficient principle has been applied in paper chromatography, thin layer chromatography, gas phase and liquid–liquid separation applications. The 1952 Nobel Prize in chemistry was earned by Archer John Porter Martin and Richard Laurence Millington Synge for their development of the technique, which was used for their separation of amino acids. Partition chromatography uses a retained solvent, on the surface or within the grains or fibers of an "inert" solid supporting matrix as with paper chromatography; or takes advantage of some coulombic and/or hydrogen donor interaction with the stationary phase. Analyte molecules partition between a liquid stationary phase and the eluent. Just as in Hydrophilic Interaction Chromatography (HILIC; a sub-technique within HPLC), this method separates analytes based on differences in their polarity. HILIC most often uses a bonded polar stationary phase and a mobile phase made primarily of acetonitrile with water as the strong component. Partition HPLC has been used historically on unbonded silica or alumina supports. Each works effectively for separating analytes by relative polar differences. HILIC bonded phases have the advantage of separating acidic, basic and neutral solutes in a single chromatographic run.

The polar analytes diffuse into a stationary water layer associated with the polar stationary phase and are thus retained. The stronger the interactions between the polar analyte and the polar stationary phase (relative to the mobile phase) the longer the elution time. The interaction strength depends on the functional groups part of the analyte molecular structure, with more polarized groups (e.g., hydroxyl-) and groups capable of hydrogen bonding inducing more retention.   Coulombic (electrostatic) interactions can also increase retention. Use of more polar solvents in the mobile phase will decrease the retention time of the analytes, whereas more hydrophobic solvents tend to increase retention times.

Normal–phase chromatography

Normal–phase chromatography was one of the first kinds of HPLC that chemists developed, but has decreased in use over the last decades. Also known as normal-phase HPLC (NP-HPLC) this method separates analytes based on their affinity for a polar stationary surface such as silica, hence it is based on analyte ability to engage in polar interactions (such as hydrogen-bonding or dipole-dipole type of interactions) with the sorbent surface. NP-HPLC uses a non-polar, non-aqueous mobile phase (e.g., Chloroform), and works effectively for separating analytes readily soluble in non-polar solvents. The analyte associates with and is retained by the polar stationary phase. Adsorption strengths increase with increased analyte polarity. The interaction strength depends not only on the functional groups present in the structure of the analyte molecule, but also on steric factors. The effect of steric hindrance on interaction strength allows this method to resolve (separate) structural isomers.

The use of more polar solvents in the mobile phase will decrease the retention time of analytes, whereas more hydrophobic solvents tend to induce slower elution (increased retention times). Very polar solvents such as traces of water in the mobile phase tend to adsorb to the solid surface of the stationary phase forming a stationary bound (water) layer which is considered to play an active role in retention.  This behavior is somewhat peculiar to normal phase chromatography because it is governed almost exclusively by an adsorptive mechanism (i.e., analytes interact with a solid surface rather than with the solvated layer of a ligand attached to the sorbent surface; see also reversed-phase HPLC below). Adsorption chromatography is still somewhat used for structural isomer separations in both column and thin-layer chromatography formats on activated (dried) silica or alumina supports.

Partition- and NP-HPLC fell out of favor in the 1970s with the development of reversed-phase HPLC because of poor reproducibility of retention times due to the presence of a water or protic organic solvent layer on the surface of the silica or alumina chromatographic media. This layer changes with any changes in the composition of the mobile phase (e.g., moisture level) causing drifting retention times.

Recently, partition chromatography has become popular again with the development of Hilic bonded phases which demonstrate improved reproducibility, and due to a better understanding of the range of usefulness of the technique.

Displacement chromatography
The use of displacement chromatography is rather limited, and is mostly used for preparative chromatography. The basic principle is based on a molecule with a high affinity for the chromatography matrix (the displacer) which is used to compete effectively for binding sites, and thus displace all molecules with lesser affinities.
There are distinct differences between displacement and elution chromatography. In elution mode, substances typically emerge from a column in narrow, Gaussian peaks. Wide separation of peaks, preferably to baseline, is desired in order to achieve maximum purification. The speed at which any component of a mixture travels down the column in elution mode depends on many factors. But for two substances to travel at different speeds, and thereby be resolved, there must be substantial differences in some interaction between the biomolecules and the chromatography matrix. Operating parameters are adjusted to maximize the effect of this difference. In many cases, baseline separation of the peaks can be achieved only with gradient elution and low column loadings. Thus, two drawbacks to elution mode chromatography, especially at the preparative scale, are operational complexity, due to gradient solvent pumping, and low throughput, due to low column loadings. Displacement chromatography has advantages over elution chromatography in that components are resolved into consecutive zones of pure substances rather than "peaks". Because the process takes advantage of the nonlinearity of the isotherms, a larger column feed can be separated on a given column with the purified components recovered at significantly higher concentration.

Reversed-phase Liquid chromatography (RP-LC)

Reversed phase HPLC (RP-HPLC) is the most widespread mode of chromatography. It has a non-polar stationary phase and an aqueous, moderately polar mobile phase. In the Reversed Phase methods, the substances are retained in the system the more hydrophobic they are.  For the retention of organic materials, the stationary phases, packed inside the columns, are consisted mainly of porous granules of silica gel in various shapes, mainly spherical, at different  diameters (1.5, 2, 3, 5, 7, 10 um), with varying pore diameters (60, 100, 150, 300, A), on whose surface are chemically bound various hydrocarbon ligands such as C3, C4, C8,C18  There are also polymeric hydrophobic particles that serve as stationary phases, when solutions at extreme pH are needed, or hybrid silica, polymerized with organic substances.  The longer the hydrocarbon ligand on the stationary phase, the longer the sample components can be retained. Most of the current methods of separation of biomedical materials use C-18 type of columns, sometimes called by a trade names such as ODS (octadecylsilane) or RP-18 (Reversed Phase 18).

The most common RP stationary phases are based on a silica support, which is surface-modified by bonding RMe2SiCl, where R is a straight chain alkyl group such as C18H37 or C8H17.

With such stationary phases, retention time is longer for lipophylic molecules, whereas polar molecules elute more readily (emerge early in the analysis). A chromatographer can increase retention times by adding more water to the mobile phase; thereby making the interactions of the hydrophobic analyte with the hydrophobic stationary phase relatively stronger. Similarly, an investigator can decrease retention time by adding more organic solvent to the mobile phase. RP-HPLC is so commonly used among the biologists and life science users, therefore it is often incorrectly referred to as just "HPLC" without further specification. The pharmaceutical industry also regularly employs RP-HPLC to qualify drugs before their release.

RP-HPLC operates on the principle of hydrophobic interactions, which originates from the high symmetry in the dipolar water structure and plays the most important role in all processes in life science. RP-HPLC allows the measurement of these interactive forces. The binding of the analyte to the stationary phase is proportional to the contact surface area around the non-polar segment of the analyte molecule upon association with the ligand on the stationary phase. This solvophobic effect is dominated by the force of water for "cavity-reduction" around the analyte and the C18-chain versus the complex of both. The energy released in this process is proportional to the surface tension of the eluent (water: 7.3 J/cm2, methanol: 2.2 J/cm2) and to the hydrophobic surface of the analyte and the ligand respectively. The retention can be decreased by adding a less polar solvent (methanol, acetonitrile) into the mobile phase to reduce the surface tension of water. Gradient elution uses this effect by automatically reducing the polarity and the surface tension of the aqueous mobile phase during the course of the analysis.

Structural properties of the analyte molecule can play an important role in its retention characteristics. In theory, an analyte with a larger hydrophobic surface area (C–H, C–C, and generally non-polar atomic bonds, such as S-S and others) can be retained longer as it is does not interact with the water structure. On the other hand, analytes with higher polar surface area (as a result of the presence of polar groups, such as -OH, -NH2, COO− or -NH3+ in their structure) are less retained, as they are better integrated into water. The interactions with the stationary phase can also affected by steric effects,  or exclusion effects, whereby a component of very large molecule may have only restricted access to the pores of the stationary phase, where the interactions with surface ligands (alkyl chains) take place.  Such surface hindrance typically results in less retention.

Retention time increases with more hydrophobic (non-polar) surface area of the molecules. For example, branched chain compounds can elute more rapidly than their corresponding linear isomers because their overall surface area is lower. Similarly organic compounds with single C–C bonds frequently elute later than those with a C=C or even triple bond, as the double or triple bond makes the molecule more compact than a single C–C bond.

Another important factor is the mobile phase pH since it can change the hydrophobic character of the ionizable analyte. For this reason most methods use a buffering agent, such as sodium phosphate, to control the pH. Buffers serve multiple purposes: control of pH which affects the ionization state of the ionizable analytes, affect the charge upon the ionizable silica surface of the stationary phase in between the bonded phase linands, and in some cases even act as ion pairing agents to neutralize analyte charge. Ammonium formate is commonly added in mass spectrometry to improve detection of certain analytes by the formation of analyte-ammonium adducts. A volatile organic acid such as acetic acid, or most commonly formic acid, is often added to the mobile phase if mass spectrometry is used to analyze the column effluents.

Trifluoroacetic acid as additive to the mobile phase is widely used for complex mixtures of biomedical samples, mostly peptides and proteins, using mostly a UV based detectors.  They are used rarely used in mass spectrometry methods, due to its residues it can leave in the detector and solvent delivery system, which interfere with the analysis and detection.  However it can be highly effective in improving retention of analytes such as carboxylic acids, in applications utilizing other detectors such as UV-VIS, as it is a fairly strong organic acid. The effects of acids and buffers vary by application but generally improve chromatographic resolution when dealing with ionizable components.

Reversed phase columns are quite difficult to damage compared to normal silica columns, thanks to the shielding effect of the bonded hydrophobic ligands; however, most reversed phase columns consist of alkyl derivatized silica particles, and are prone to hydrolysis of the silica at extreme pH conditions in the mobile phase. Most types of RP columns should not be used with aqueous bases as these will hydrolyze the underlying silica particle and dissolve it. There are selected brands of hybrid or enforced silica based particles of RP columns which can be used at extreme pH conditions.  The use of extreme acidic conditions is also not recommended, as they also might hydrolyzed as well as corrode the inside walls of the metallic parts of the HPLC equipment.

As a rule, in most cases RP-HPLC columns should be flushed with clean solvent after use to remove residual acids or buffers, and stored in an appropriate composition of solvent. Some biomedical applications require non metallic environment for the optimal separation. For such sensitive cases there is a test for the metal content of a column is to inject a sample which is a mixture of 2,2'- and 4,4'-bipyridine. Because the 2,2'-bipy can chelate the metal, the shape of the peak for the 2,2'-bipy will be distorted (tailed) when metal ions are present on the surface of the silica...

Size-exclusion chromatography

Size-exclusion chromatography (SEC) separates polymer molecules and biomolecules based on differences in their molecular size (actually by a particle's Stokes radius). The separation process is based on the ability of sample molecules to permeate through the pores of gel spheres, packed inside the column, and is dependent on the relative size of analyte molecules and the respective pore size of the absorbent. The process also relies on the absence of any interactions with the packing material surface.

Two types of SEC are usually termed:

1. Gel permeation chromatography (GPC)—separation of synthetic  polymers (aqueous or organic soluble). GPC is a powerful technique for polymer characterization using primarily organic solvents.

2. Gel filtration chromatography (GFC)—separation of water-soluble biopolymers. GFC uses primarily aqueous solvents (typically for aqueous soluble biopolymers, such as proteins, etc.).

The separation principle in SEC is based on the fully, or partially penetrating of the high molecular weight substances of the sample into the porous stationary-phase particles during their transport through column. The mobile-phase eluent is selected in such a way that it totally prevents interactions with the stationary phase's surface. Under these conditions, the smaller the size of the molecule, the more it is able to penetrate inside the pore space and the movement through the column takes longer. On the other hand, the bigger the molecular size, the higher the probability the molecule will not fully penetrate the pores of the stationary phase, and even travel around them, thus, will be eluted earlier. The molecules are separated in order of decreasing molecular weight, with the largest molecules eluting from the column first and smaller molecules eluting later. Molecules larger than the pore size do not enter the pores at all, and elute together as the first peak in the chromatogram and this is called total exclusion volume which defines the exclusion limit for a particular column. Small molecules will permeate fully through the pores of the stationary phase particles and will be eluted last, marking the end of the chromatogram, and may appear as a total penetration marker.

In biomedical sciences it is generally considered as a low resolution chromatography and thus it is often reserved for the final, "polishing" step of the purification. It is also useful for determining the tertiary structure and quaternary structure of purified proteins. SEC is used primarily for the analysis of large molecules such as proteins or polymers. SEC works also in a preparative way by trapping the smaller molecules in the pores of a particles. The larger molecules simply pass by the pores as they are too large to enter the pores. Larger molecules therefore flow through the column quicker than smaller molecules, that is, the smaller the molecule, the longer the retention time.

This technique is widely used for the molecular weight determination of polysaccharides. SEC is the official technique (suggested by European pharmacopeia) for the molecular weight comparison of different commercially available low-molecular weight heparins.

Ion-exchange chromatography

Ion-exchange chromatography (IEC) or Ion chromatography (IC) is an analytical technique for the separation and determination of ionic solutes in aqueous samples from environmental and industrial origins such as metal industry, industrial waste water, in biological systems, pharmaceutical samples, food, etc. Retention is based on the attraction between solute ions and charged sites bound to the stationary phase. Solute ions charged the same as the ions on the column are repulsed and elute without retention, while solute ions charged oppositely to the charged sites of the column are retained on it. Solute ions that are retained on the column can be eluted from it by changing the mobile phase composition, such as increasing its salt concentration and pH or increasing the column temperature, etc..

Types of ion exchangers include polystyrene resins, cellulose and dextran ion exchangers (gels), and controlled-pore glass or porous silica gel. Polystyrene resins allow cross linkage, which increases the stability of the chain. Higher cross linkage reduces swerving, which increases the equilibration time and ultimately improves selectivity. Cellulose and dextran ion exchangers possess larger pore sizes and low charge densities making them suitable for protein separation

In general, ion exchangers favor the binding of ions of higher charge and smaller radius.

An increase in counter ion (with respect to the functional groups in resins) concentration reduces the retention time, as it creates a strong competition with the solute ions. A decrease in pH reduces the retention time in cation exchange while an increase in pH reduces the retention time in anion exchange. By lowering the pH of the solvent in a cation exchange column, for instance, more hydrogen ions are available to compete for positions on the anionic stationary phase, thereby eluting weakly bound cations.

This form of chromatography is widely used in the following applications: water purification, preconcentration of trace components, ligand-exchange chromatography, ion-exchange chromatography of proteins, high-pH anion-exchange chromatography of carbohydrates and oligosaccharides, and others.

Bioaffinity chromatography or

High Performance Affinity Chromatography, HPAC, works by passing a sample solution through a column packed with a stationary phase that contains an immobilized biologically active ligand. The ligand is in fact a substrate that has a specific binding affinity for the target molecule in the sample solution. The target molecule binds to the ligand, while the other molecules in the sample solution pass through the column, having little or no retention. The target molecule is then eluted from the column using a suitable elution buffer.

This chromatographic process relies on the capability of the bonded active substances to form stable, specific, and reversible complexes thanks to their biological recognition of certain specific sample components. The formation of these complexes involves the participation of common molecular forces such as the Van der Waals interaction, electrostatic interaction, dipole-dipole interaction, hydrophobic interaction, and the hydrogen bond. An efficient, biospecific bond is formed by a simultaneous and concerted action of several of these forces in the complementary binding sites.

Aqueous normal-phase chromatography
Aqueous normal-phase chromatography (ANP) is also called Hydrophilic Interaction Liquid Chromatography, HILIC. This is a chromatographic technique which encompasses the mobile phase region between reversed-phase chromatography (RP) and organic normal phase chromatography (ONP). HILIC is used to achieve unique selectivity for hydrophilic compounds, showing normal phase elution order, using "reversed-phase solvents", i.e., relatively polar mostly non-aqueous solvents in the mobile phase. Many biological molecules, especially those found in biological fluids, are small polar compounds that do not retain well by Reversed Phase-HPLC. This has made hydrophilic interaction LC (HILIC) an attractive alternative and useful approach for analysis of polar molecules. Additionally, because HILIC is routinely used with traditional aqueous mixtures with polar organic solvents such as ACN and methanol, it can be easily coupled to MS.

Isocratic and gradient elution

A separation in which the mobile phase composition remains constant throughout the procedure is termed isocratic (meaning constant composition). The word was coined by Csaba Horvath who was one of the pioneers of HPLC.

The mobile phase composition does not have to remain constant. A separation in which the mobile phase composition is changed during the separation process is described as a gradient elution. For example, a gradient can start at 10% methanol in water, and end at 90% methanol in water after 20 minutes. The two components of the mobile phase are typically termed "A" and "B"; A is the "weak" solvent which allows the solute to elute only slowly, while B is the "strong" solvent which rapidly elutes the solutes from the column. In reversed-phase chromatography, solvent A is often water or an aqueous buffer, while B is an organic solvent miscible with water, such as acetonitrile, methanol, THF, or isopropanol.

In isocratic elution, peak width increases with retention time linearly according to the equation for N, the number of theoretical plates. This can be a major disadvantage when analyzing a sample that contains analytes with a wide range of retention factors. Using a weaker mobile phase, the runtime is lengthened and results in slowly eluting peaks to be broad, leading to reduced sensitivity. A stronger mobile phase would improve issues of runtime and broadening of later peaks but results in diminished peak separation, especially for quickly eluting analytes which may have insufficient time to fully resolve. This issue is addressed through the changing mobile phase composition of gradient elution.

By starting from a weaker mobile phase and strengthening it during the runtime, gradient elution decreases the retention of the later-eluting components so that they elute faster, giving narrower (and taller) peaks for most components, while also allowing for the adequate separation of earlier-eluting components. This also improves the peak shape for tailed peaks, as the increasing concentration of the organic eluent pushes the tailing part of a peak forward. This also increases the peak height (the peak looks "sharper"), which is important in trace analysis. The gradient program may include sudden "step" increases in the percentage of the organic component, or different slopes at different times – all according to the desire for optimum separation in minimum time.

In isocratic elution, the retention order does not change if the column dimensions (length and inner diameter) change – that is, the peaks elute in the same order. In gradient elution, however, the elution order may change as the dimensions or flow rate change. if they are no scaled down or up according to the change

The driving force in reversed phase chromatography originates in the high order of the water structure. The role of the organic component of the mobile phase is to reduce this high order and thus reduce the retarding strength of the aqueous component.

Parameters

Theoretical
The theory of High     performance liquid chromatography-HPLC is basically the same as general chromatography     theory, which is defined as a separation technique for mixtures of compounds, based on the differences in their distribution coefficient between two phases, the stationary phase, packed inside a column and the liquid mobile phase, flowing through the columns by high pressure pumps. Components whose distribution into the stationary phase is higher, are retained longer, and get separated from those with lower distribution into the stationary phase. The theoretical and practical foundations of this method were laid by A. J. P. Martin and R. L. M. Synge who received Nobel prize for it. The theory of chromatography has been used as the basis for System-Suitability tests, as can be seen in the USP Phamacopaeia, which are a set of quantitative criteria, which test the suitability of the HPLC system to the required analysis at any step of it.

The distribution coefficient of a solute between the stationary and the mobile phase is proportional to the parameter called the Capacity Factor, or Capacity Ratio, k', which is defined as shown in the Figure of the Chromatographic Performance Criteria. Where Cs is the concentration of the solute at the stationary phase and Cm is its concentration at the mobile phase while Φ is the volume ratio of the stationary and mobile phase within the solute's zone.

he time elapsed between the injection time of the sample component into the column and its detection time is known as the Retention Time (RT or tR).   The retention time is longer, when the solute has higher distribution coefficient, due to its chemical nature. For example, in reverse phase chromatography, the more lipophilic is a compound, the higher is its distribution coefficient between the stationary and the mobile phases, so it is retained longer. Therefore, it is obvious that there is a direct relation between the distribution coefficient and the capacity factor k' and the solute retention time.

This relation is also represented as a normalized unit-less factor known as the Retention Factor, or Retention parameter, which is the experimental measurement of the capacity ratio, as shown in the Figure of Performance Criteria as well. tR is the retention time of the specific component and t0 is the time it takes for a non-retained substance to elute through the system without any retention, thus it is called the Void Time.

The ratio between the Retention Factors, k', of every two adjacent peaks in the chromatogram is used in the evaluation of the degree of separation between them, and is called Selectivity Factor, α, as shown in the Performance Criteria graph.

The width of a peak, relative to its retention time is a measure of the system's efficiency, calculated as N, Plate Count. The migration through the column causes band-broadening, due to eddy diffusion, lateral diffusion and molecular diffusion, mass-transfer kinetics between the two phases, as well as extra-column effects, which reduce the efficiency of the chromatographic system.  The narrower the peak, the better is the separation, as well as the limit of detection and limit of quantification of the chromatographic system, because the detector response is higher for a specific area. When the response is higher, the signal-to-noise is better, hence the system is capable of detecting lower concentrations. At the same time, the narrower is the peak for a given retention time, the better can be the resolution between every two adjacent peaks.

The efficiency of the separation, N, the Plate Count is measured as shown in the Figure of Performance Criteria. Where tR is the retention time and w(baseline) is measured from the baseline peak width, calculated using lines tangential to the peak width at 50 % height.

The Plate Count N as a criterion for system efficiency was developed for isocratic conditions, i.e., a constant mobile phase composition throughout the run. In gradient conditions, where the mobile phase changes with time during the chromatographic run, it is more appropriate to use the parameter Peak Capacity Pc as a measure for the system efficiency. The definition of Peak Capacity in chromatography is the number of peaks that can be separated within a retention window for a specific pre-defined Resolution Factor, usually ~1. It could also be envisioned as the runtime measured in number of peaks' average widths. The equation is shown in the Figure of  the performance criteria. In this equation tg is the gradient time and w(ave) is the average peaks width at the base.

The chromatographic peak is assumed to have a Gaussian shape under ideal conditions, describing normal distribution of the velocity of the molecules populating the peak zone, migrating through the stationary phase inside the column.  Any deviation from the normal distribution indicates non-ideal distribution during the migration process, therefore might jeopardize the integrity of the peak's integration, reducing the accuracy of the quantitation. There are many experimental and chemical parameters that cause peak asymmetry, such as non-ideal connections or column's packing, insufficient pH buffering, solutes overloading, etc.

The deviation from symmetry is measured by the Asymmetry Factor,  Af  or  Tailing Factor  Tf.  Both equations are found in the Figure of the Performance Criteria. The calculation of Asymmetry Factor, Af  is calculated from the lines A and B , which are sections in the horizontal line parallel to the baseline, drawn at 10% of the peak height as shown in the Figure.  The calculation of Tailing Factor, Tf, which is more widely used in the pharmaceutical industry, as suggested by the pharmacopeias, is also calculated from A and B, the sections in the horizontal line parallel to the baseline, but at 5% of the peak height The USP suggests that Tailing Factor should be in the range of 0.5 up to 2 to assure a precise and accurate quantitative measurement.

The parameters are largely derived from two sets of chromatographic theory: plate theory (as part of Partition chromatography), and the rate theory of chromatography / Van Deemter equation. Of course, they can be put in practice through analysis of HPLC chromatograms, although rate theory is considered the more accurate theory.

They are analogous to the calculation of retention factor for a paper chromatography separation, but describes how well HPLC separates a mixture into two or more components that are detected as peaks (bands) on a chromatogram. The HPLC parameters are the: efficiency factor(N), the retention factor (kappa prime), and the separation factor (alpha). Together the factors are variables in a resolution equation, which describes how well two components' peaks separated or overlapped each other. These parameters are mostly only used for describing HPLC reversed phase and HPLC normal phase separations, since those separations tend to be more subtle than other HPLC modes (e.g., ion exchange and size exclusion).

Void volume is the amount of space in a column that is occupied by solvent. It is the space within the column that is outside of the column's internal packing material. Void volume is measured on a chromatogram as the first component peak detected, which is usually the solvent that was present in the sample mixture; ideally the sample solvent flows through the column without interacting with the column, but is still detectable as distinct from the HPLC solvent. The void volume is used as a correction factor.

Efficiency factor (N) practically measures how sharp component peaks on the chromatogram are, as ratio of the component peak's area ("retention time") relative to the width of the peaks at their widest point (at the baseline). Peaks that are tall, sharp, and relatively narrow indicate that separation method efficiently removed a component from a mixture; high efficiency. Efficiency is very dependent upon the HPLC column and the HPLC method used. Efficiency factor is synonymous with plate number, and the 'number of theoretical plates'.

Retention factor (kappa prime) measures how long a component of the mixture stuck to the column, measured by the area under the curve of its peak in a chromatogram (since HPLC chromatograms are a function of time). Each chromatogram peak will have its own retention factor (e.g., kappa1 for the retention factor of the first peak). This factor may be corrected for by the void volume of the column.

Separation factor (alpha) is a relative comparison on how well two neighboring components of the mixture were separated (i.e., two neighboring bands on a chromatogram). This factor is defined in terms of a ratio of the retention factors of a pair of neighboring chromatogram peaks, and may also be corrected for by the void volume of the column. The greater the separation factor value is over 1.0, the better the separation, until about 2.0 beyond which an HPLC method is probably not needed for separation.
Resolution equations relate the three factors such that high efficiency and separation factors improve the resolution of component peaks in an HPLC separation.

Internal diameter

The internal diameter (ID) of an HPLC column is an important parameter..  It can influences the detection response, when reduced, thanks to the reduced lateral diffusion of the solute band. It can also affect the separation selectivity, when flow rate and injection volumes are not scaled down or up proportionally to the smaller or larger diameter used, both in the isocratic and in gradient modes. It determines the quantity of analyte that can be loaded onto the column. Larger diameter columns are usually seen in preparative applications, such as the purification of a drug product for later use. Low-ID columns have improved sensitivity and lower solvent consumption in the recent Ultra-High Performance Liquid Chromatography (UHPLC).

Larger ID columns (over 10 mm) are used to purify usable amounts of material because of their large loading capacity.

Analytical scale columns (4.6 mm) have been the most common type of columns, though narrower columns are rapidly gaining in popularity. They are used in traditional quantitative analysis of samples and often use a UV-Vis absorbance detector.

Narrow-bore columns (1–2 mm) are used for applications when more sensitivity is desired either with special UV-vis detectors, fluorescence detection or with other detection methods like liquid chromatography-mass spectrometry

Capillary columns (under 0.3 mm) are used almost exclusively with alternative detection means such as mass spectrometry. They are usually made from fused silica capillaries, rather than the stainless steel tubing that larger columns employ.

Particle size
Most traditional HPLC is performed with the stationary phase attached to the outside of small spherical silica particles (very small beads). These particles come in a variety of sizes with 5 µm beads being the most common. Smaller particles generally provide more surface area and better separations, but the pressure required for optimum linear velocity increases by the inverse of the particle diameter squared.

According to the equations of the column velocity, efficiency and backpressure, reducing the particle diameter by half and keeping the size of the column the same, will double the column velocity and efficiency; but four times increase the backpressure. And the small particles HPLC also can decrease the width broadening. Larger particles are used in preparative HPLC (column diameters 5 cm up to >30 cm) and for non-HPLC applications such as solid-phase extraction.

Pore size
Many stationary phases are porous to provide greater surface area. Small pores provide greater surface area while larger pore size has better kinetics, especially for larger analytes. For example, a protein which is only slightly smaller than a pore might enter the pore but does not easily leave once inside.

Pump pressure
Pumps vary in pressure capacity, but their performance is measured on their ability to yield a consistent and reproducible volumetric flow rate. Pressure may reach as high as 60 MPa (6000 lbf/in2), or about 600 atmospheres. Modern HPLC systems have been improved to work at much higher pressures, and therefore are able to use much smaller particle sizes in the columns (<2 μm). These "ultra high performance liquid chromatography" systems or UHPLCs, which could also be known as ultra high pressure chromatography systems, can work at up to 120 MPa (17,405 lbf/in2), or about 1200 atmospheres. The term "UPLC" is a trademark of the Waters Corporation, but is sometimes used to refer to the more general technique of UHPLC.

Detectors
HPLC detectors fall into two main categories: universal or selective. Universal detectors typically measure a bulk property (e.g., refractive index) by measuring a difference of a physical property between the mobile phase and mobile phase with solute while selective detectors measure a solute property (e.g., UV-Vis absorbance) by simply responding to the physical or chemical property of the solute. HPLC most commonly uses a UV-Vis absorbance detector, however, a wide range of other chromatography detectors can be used. A universal detector that complements UV-Vis absorbance detection is the Charged aerosol detector (CAD). A kind of commonly utilized detector includes refractive index detectors, which provide readings by measuring the changes in the refractive index of the eluant as it moves through the flow cell. In certain cases, it is possible to use multiple detectors, for example LCMS normally combines UV-Vis with a mass spectrometer.

When used with an electrochemical detector (ECD) the HPLC-ECD selectively detects neurotransmitters such as: norepinephrine, dopamine, serotonin, glutamate, GABA, acetylcholine and others in neurochemical analysis research applications. The HPLC-ECD detects neurotransmitters to the femtomolar range. Other methods to detect neurotransmitters include liquid chromatography-mass spectrometry, ELISA, or radioimmunoassays.

Autosamplers
Large numbers of samples can be automatically injected onto an HPLC system,  by the use of HPLC autosamplers.  In addition, HPLC autosamplers have an injection volume and technique which is exactly the same for each injection, consequently they provide a high degree of injection volume precision.
It is possible to enable sample stirring within the sampling-chamber, thus promoting homogeneity.

Applications

Manufacturing
HPLC has many applications in both laboratory and clinical science. It is a  common technique used in pharmaceutical development, as it is a dependable way to obtain and ensure product purity. While HPLC can produce extremely high quality (pure) products, it is not always the primary method used in the production of bulk drug materials. According to the European pharmacopoeia, HPLC is used in only 15.5% of syntheses. However, it plays a role in 44% of syntheses in the United States pharmacopoeia. This could possibly be due to differences in monetary and time constraints, as HPLC on a large scale can be an expensive technique. An increase in specificity, precision, and accuracy that occurs with HPLC unfortunately corresponds to an increase in cost.

Legal
This technique is also used for detection of illicit drugs in various samples. The most common method of drug detection has been an immunoassay. This method is much more convenient. However, convenience comes at the cost of specificity and coverage of a wide range of drugs, therefore, HPLC as been used as well as an alternative method. As HPLC is a method of determining (and possibly increasing) purity, using HPLC alone in evaluating concentrations of drugs was somewhat insufficient. Therefore, HPLC in this context is often performed in conjunction with mass spectrometry. Using liquid chromatography-mass spectrometry (LC-MS) instead of gas chromatography-mass spectrometry (GC-MS) circumvents the necessity for derivitizing with acetylating or alkylation agents, which can be a burdensome extra step. LC-MS has been used to detect a variety of agents like doping agents, drug metabolites, glucuronide conjugates, amphetamines, opioids, cocaine, BZDs, ketamine, LSD, cannabis, and pesticides. Performing HPLC in conjunction with mass spectrometry reduces the absolute need for standardizing HPLC experimental runs.

Research
Similar assays can be performed for research purposes, detecting concentrations of potential clinical candidates like anti-fungal and asthma drugs. This technique is obviously useful in observing multiple species in collected samples, as well, but requires the use of standard solutions when information about species identity is sought out. It is used as a method to confirm results of synthesis reactions, as purity is essential in this type of research. However, mass spectrometry is still the more reliable way to identify species.

Medical and Health Sciences
Medical use of HPLC typically use Mass Spectrometer (MS) as the detector, so the technique is called LC-MS or LC-MS/MS for tandem MS, where two types of MS are operated sequentially. When HPLC instrument is connected to more than one detector, it is called Hyphenated LC system.  Pharmaceutical applications are the major users of HPLC, LC-MS and LC-MS/MS.  This include drug development and pharmacology, which is the scientific study of the effects of drugs and chemicals on living organisms, personalized medicine, public health and diagnostics. While urine is the most common medium for analyzing drug concentrations, blood serum is the sample collected for most medical analyses with HPLC. One of the most important roles of LC-MS and LC-MS/MS in the clinical lab is the Newborn Screening (NBS) for metabolic disorders and follow-up diagnostics. The infants' samples come in the shape of dried blood spot (DBS), which is simple to prepare and transport, enabling safe and accessible diagnostics, both locally and globally.

Other methods of detection of molecules that are useful for clinical studies have been tested against HPLC, namely immunoassays. In one example of this, competitive protein binding assays (CPBA) and HPLC were compared for sensitivity in detection of vitamin D. Useful for diagnosing vitamin D deficiencies in children, it was found that sensitivity and specificity of this CPBA reached only 40% and 60%, respectively, of the capacity of HPLC. While an expensive tool, the accuracy of HPLC is nearly unparalleled.

See also
History of chromatography
Capillary electrochromatography
Column chromatography
Csaba Horváth
Ion chromatography
Micellar liquid chromatography

References

Further reading

 L. R. Snyder, J.J. Kirkland, and J. W. Dolan, Introduction to Modern Liquid Chromatography, John Wiley & Sons, New York, 2009.
 M.W. Dong, Modern HPLC for practicing scientists. Wiley, 2006.
 L. R. Snyder, J.J. Kirkland, and J. L. Glajch, Practical HPLC Method Development, John Wiley & Sons, New York, 1997.
 S. Ahuja and H. T. Rasmussen (ed), HPLC Method Development for Pharmaceuticals, Academic Press, 2007.
 S. Ahuja and M.W. Dong (ed), Handbook of Pharmaceutical Analysis by HPLC, Elsevier/Academic Press, 2005.
 Y. V. Kazakevich and R. LoBrutto (ed.), HPLC for Pharmaceutical Scientists, Wiley, 2007.
 U. D. Neue, HPLC Columns: Theory, Technology, and Practice, Wiley-VCH, New York, 1997.
 M. C. McMaster, HPLC, a practical user's guide, Wiley, 2007.

External links

 HPLC Chromatography Principle, Application [Basic Note] – 2020. at Rxlalit.com

Hungarian inventions
Chromatography
Scientific techniques

High-performance liquid chromatography


Wilhelm Bodewin Johann Gustav Keitel (Born ; 22 September 1882 in Helmscherode,Duchy Of Brunswick, Germany– Died ; 16 October 1946 in Nuremberg, Bavaria, Germany) was a German field marshal and a Nazi War Criminal between 1938 and 1945 the chief of the "Oberkommando der Wehrmacht". He was one of the 24 accused of the Nuremberg Trials and hanged in 1946.

Wilhelm Bodewin Johann Gustav Keitel was in 22 September 1882 and he is 7 year's older then Adolf Hitler . He was born in Helmscherode in the State Of Germany Duchy Of Brunswick (Today Lower Saxony) he joined the Imperial German Army in 1901 at age 19 just 13 year's before World War 1 in July and August 1914 . After Archduke Franz Ferdinand was Assassinated by Gavrilo Princip on 28 June 1914 in Sarajevo in Bosnia in the Austro-Hungarian Empire (later part of Yugoslavia in 1918 and today part of Bosnia and Herzegovina) Austria-Hungary declared war on Serbia for the  assassination and the German Empire lead by Kaiser Wilhelm II  declared war on Russia for supporting Serbia and later declared war on France while Japan declared war on the German Colonies and Germany launch the Schlieffen Plan (planned by Alfred Graf Von Schliffen in 1905-1906) in August 1914 at the Battle of the Marne but failed in September 1914 Wilhelm Keitel was on the Western Front in World War 1 he took part in Flanders fighting in Belgium (lead by King Albert I of Belgium after King Leopold II of Belgium died in 1909) . Keitel was wounded as a German Soldier in WW1 from 1914-1918 . After the end of the Great War in 1918 and the Collapse and defeat of the German Empire ,Austria-Hungary and the Ottoman Empire (except Bulgaria) in 1918 by Britain,France,Italy and America he joined the Reichswehr in 1919 during the Weimar Republic Era Germany until 1933 when Adolf Hitler,along with Ernst Röhm,Hermann Göring,Rudolf Hess,Joseph Goebbels,Heinrich Himmler,Reinhard Heydrich,Adolf Eichmann,Hans Lammers,Ernst Kaltenbrunner,Martin Bormann,Rudolf Höss,Hans Frank,Alfred Rosenberg,Joachim von Ribbentrop,Kurt Daluege and the Nazi Party and all the other Nazi Officals came to power and took over Germany on 30 January 1933 . In May 1945 Admiral Karl Donitz surrendered Nazi Germany to the Soviet Union,the United States,France,and Britain Germany was a occupied country until 1949 when it got split into the Federal Republic Of Germany (West Germany) and the German Democratic Republic (East Germany) . During the Nuremberg Trials in 1946 Keitel was convicted as a Nazi War Criminal and was executed on 16th October 1946 aged 64 for War Crimes . Wilhelm Keitel also appeared in the movie Downfall (2004 movie) .

1882 births
1945 deaths
Executed German people
German generals of World War II
German war criminals
Government ministers of Nazi Germany
People executed by hanging

Wilhelm Keitel


End of the World () is a 1931 French science fiction film directed by Abel Gance based on the novel Omega: The Last Days of the World by Camille Flammarion. The film stars Victor Francen as Martial Novalic, Colette Darfeuil as Genevieve de Murcie, Abel Gance as Jean Novalic, and Jeanne Brindau as Madame Novalic. The plot concerns a comet hurtling toward Earth on a collision course and the different reactions people have to the impending disaster. Scientist Martial Novalic who discovers the comet, seeks a solution to the problem and becomes a fugitive after skeptical authorities blame him for starting a mass panic.

End of the World was director Abel Gance's first sound film. The original film was to be over three hours long, but the backing production took the film from Gance, and cut it to be 105 minutes. It was again cut on its release in the United States under the title of Paris after Dark. Neither abridged version of the film was well received by audiences or critics.

Plot
Jean Novalic plays Jesus Christ in a passion play. Isabelle Bolin attends with her boyfriend, stock promoter Schomburg, who is entranced by the blonde actress playing Mary Magdalene, Genevieve de Murcie. Genevieve defies her scientist father Monsieur de Murcie to propose to Jean, who tells her that they cannot marry. Back home, Genevieve's father, jealous of the wealthy Martial Novalic's fame, accepts money from Schomburg to build an observatory better than Novalic's. Schomburg then announces his intention to court de Murcie's daughter.

As Jean aids a young woman being abused, he is accused of rape and is critically wounded by a blow to the head. Schomburg accompanies Genevieve to a fancy party, but takes her back to her apartment and rapes her. In his observatory, Martial determines that Lexell's Comet is on a collision course with Earth. Jean predicts a coming apocalypse and claims that the cataclysm has arrived to "save the hearts of man". Martial confides to his colleagues that the comet will strike in 114 days. After Jean is taken to an asylum, Martial and Genevieve listen to his phonographs, which instruct Genevieve to abandon her worldly life and help Martial inaugurate a new world government. Jean's voice tells them they must marry and become the shepherd and shepherdess of humanity. Genevieve sees a vision of Jean as Christ.

With 92 days left, Schomburg invests heavily in armaments, while Martial goes to the rich Werster and tells him that the world will end. Werster deals with Schomburg and gives Martial money to buy a newspaper and a broadcast station. Genevieve has remained single, but helps to organize Radio Martial Novalic's broadcasts of peace bulletins. Martial's confederates jam official radio news, blocking warnings that war mobilization is imminent. Martial announces the coming end of the world. Stock markets plunge around the globe, but Schomburg continues to buy. De Murcie and Schomburg accuse Novalic of kidnapping Genevieve and using the comet as a hoax to destroy the economy. A government minister orders the exchanges closed and the arrest of Martial and Werster. But Martial's agents learn of the arrest warrant with a hidden microphone. The newspaper is confiscated and the radio station destroyed, but Martial and Werster escape.

The government hides the truth, which allows the stock markets to recover. Schomberg holds a party the very night Martial claims that the comet will become visible. Schomberg tells gangsters he will pay a million francs if Martial and Werster are found dead before morning. Genevieve returns to her father and joins Schomburg in the garden; the jealous Isabelle runs to warn Martial Novalic. At the party, the comet comes into sight. Isabelle helps Martial escape and learns that war mobilization will soon be announced. He and Werster rush to destroy the government's radio antenna in the Eiffel Tower. Genevieve tips off Martial by telephone that Schomburg and his killers are ascending in an elevator. Werster warns Genevieve to stay on the ground and uses a cutting torch to sever the elevator cable, but Genevieve had taken the elevator as well and is killed with the rest.

The entire world can now see Lexell's Comet, and Radio Novalic resumes broadcasting. Martial calls for the first convention of the "General States of the Universe" on 5 August, the night before the collision. People around the world begin to pray as the comet looms larger in the sky and extreme weather ensues, including blizzards, storms, tidal waves. Riots break out and a thousand revelers bring musicians into a great hall for a feast and orgy. Monks carrying candles interrupt the orgy and lead the group in prayer. As the orbits of the comet and the Earth converge, Martial Novalic addresses the One World Congress, which unanimously agrees to unite all governments into a single harmonious entity. The comet narrowly misses the Earth. Much of the world has been reduced to rubble, but life will go on.

Production

Director Abel Gance had meditated on the idea of End of the World since 1913 and after creating the film Napoleon in 1927, he convinced himself and backers to go forward with the project. Gance originally was going to title the film The End of the World, as Seen, Heard and Rendered, by Abel Gance. Filming began in mid-1929 and was finished roughly a year later. The film had been edited to a running time of just over three hours. When the backers felt that the film was becoming far too long, they took production control away from Gance and cut the film to 105 minutes.

It was shot at the Joinville Studios in Paris.

Cast
 Abel Gance as Jean Novalic
 Colette Darfeuil as Genevieve de Murcie
 Sylvie Gance as Isabelle Bolin (as Sylvie Grenade)
 Jeanne Brindeau as Mme. Novalic
 Samson Fainsilber as Schomburg
 Georges Colin as Werster
 Jean d'Yd as M. de Murcie
 Victor Francen as Martial Novalic

Release
The film was released in France in January 1931 under the title La Fin du monde at a rough length of 105 minutes and was never shown in the United States in this form. Although American director Cecil B. DeMille showed interest in purchasing the rights to the film, it was released in 1934 by American film distributor Harold Auten who trimmed the running time to 54 minutes in the fashion of various exploitation films of the time. Auten's version was re-titled Paris After Dark and included a new opening by Dr. Clyde Fisher discussing the scientific nature of the film. Auten's version of the film removed most of the film's dialogue filling it with title cards and made the leading character Jean Novalic into a minor character who only has a few scenes in the background.

Reception
The film received a disastrous reception from audiences and critics alike. Contemporary critic Philippe Soupault described it as "portentously naive" and "blatantly unrealistic". Director Abel Gance himself referred to the film as "an abortive work" ruined by the producer taking the film away from him so he could edit it himself.

The lack of success of End of the World forced Gance to turn to more conventional projects in order to continue work as a filmmaker.

See also
 1931 in science fiction

References

Further reading

External links

1931 films
1930s French-language films
1930s science fiction films
French science fiction films
French disaster films
French black-and-white films
Films directed by Abel Gance
Apocalyptic films
Films about impact events
Films shot at Joinville Studios
Films scored by Arthur Honegger
1930s French films

End of the World (1931 film)


Legion of Fire: Killer Ants! (alternatively titled Marabunta) is a 1998 made for TV  horror movie, made for the Fox TV channel.

In 2005, Legion of Fire: Killer Ants! was released on DVD in Germany under the title Marabunta. No announcement has been made on the possibility of an English language release, although it is still shown regularly during the Sci Fi Channel's weekend movie marathons under its alternative name Marabunta. It is also available on NowTV.

Plot
Dr. Jim Conrad is visiting the small town of Burly Pines, Alaska to fish. While out with a friend, they discover a moose that has been stripped clean of meat.  They presume hunters left it for scavengers, but then the hunters arrive and say they had shot it two hours earlier and had been tracking it since. A shopkeeper is found in the same condition in his home. The authorities think it may have been a predator, but Jim is unsure. During the autopsy, Jim finds something on the man's body. When he looks at it under a microscope, it is the jaws of a marabunta, a South American ant known for traveling in waves, killing everything in their path. After questioning Police Chief Jeff Croy and his men, Jim figures out that the ants must have arrived on a boat that had crashed a few years ago, leaving logs of South American wood behind. The ants had hibernated in the wood until recent seismic activity had made it warm enough to support them.

Jim teams up with Croy and schoolteacher Laura to try to find a way to stop the ants. Jim and Karen go to the beach where the wood from the ship washed up to kill the queen. The ants attack Jim's friend, who is piloting the helicopter. While trying to fight them off, his actions cause the helicopter to lift off and crash into the mountain. Jim and Laura find themselves surrounded by the ants. They hold them off using a flame thrower and shotgun until they can reach a nearby canoe, which they take downstream until they reach a waterfall and go over it. Having survived the falls, they find an old cabin with a motorcycle. They get it started just as the ants reach them and ride it back to town. They convince Croy to evacuate the town. Croy has local Native American Gray Wolf handle the evacuation and tells his son Chad to go with them. When everyone is out of town, Gray Wolf is to blow up the only road out of town. Chad goes back to his father against his wishes and returns to help while Gray Wolf sets up the dynamite. At the school, Jim and Laura create a mixture that can kill the ants, but the ants attack the school. Chad gets trapped in a school bus while Jim and Laura are chased to the school's top floor. Croy arrives in his truck, and they escape with help from Jim's formula. They make their way out of town, but Gray Wolf is forced to blow the pass early when he sees the ants making their way along it.

After determining the ants' pattern, they decide to blow up the local dam and flood the entire town to kill the ants. Jim and Laura get some dynamite and head to the dam. They leave Chad in Croy's truck parked on top of the dam as a lookout while they dig holes in the earthen side of the dam at intervals and insert the dynamite with different length fuses. While they are working, a rescue helicopter, sent by Gray Wolf, arrives to carry them out of town. Chad gets in, and once they have lit the dynamite, Croy and Karen join him. Jim has trouble lighting his fuse, and an aftershock knocks him down, but he is finally able to get it lit. The pilot flies the helicopter down to where Jim is, and, with Croy's help, he gets aboard just as the dynamite explodes.

The dam is destroyed, and the water floods the entire valley, including the town. The pilot lands the helicopter on a nearby hill, and the group looks at the flooded valley, hoping the ants have drowned. Jim decides to stay for a while to study the area more. He warns the group that they cannot be sure all of the ants died and that any survivors would probably go back underground and into hibernation. As the movie ends, surviving ants, including the queen, are shown walking on some stones near the water's edge, where it is discovered the queen has wings, thus potentially repeating the cycle.

Cast
 Eric Lutes as Dr. James Conrad
 Julia Campbell as Laura Sills
 Mitch Pileggi as Police Chief Jeff Croy
 Jeremy Foley as Chad Croy
 Bill Ozbourne as Officer Dave Blount
 Dallen Gettling as Bob Hazzard
 Patrick Fugit as Scott Blount
 H.E.D. Redford as Maynerd Perth
 Don Shanks as Greywolf
 Kim Landry as Sarah
 Jeanette Puchich as Margie
 Duane Stephens as Hunter # 1
 Rob Greyhill as Hunter # 2
 Rick Lichenhan as Resident at Pass
 Christine Romeo as Fran
 Ron Sarchian as Glenn

Critical reception
The movie did not fare well with critics. In the Minneapolis Star Tribune, a reviewer commented that the movie "continues a great, cheesy tradition of ant-menace movies." The Encyclopedia of Fantastic Film calls it a "standard SF-thriller."
Eric Fowler at the Indianapolis Morning Register was less kind, calling the film, "a blot on the history of sci-fi and an insult to ants everywhere."

References

External links

1998 television films
1998 films
1998 horror films
1990s disaster films
American disaster films
American science fiction horror films
Disaster television films
Films about ants
Fox network original films
American horror television films
Films scored by Daniel Licht
1990s English-language films
1990s American films

Legion of Fire: Killer Ants!


Book trimming is the stage of the book production process in which the page edges of a book are trimmed so that all pages will stack with perfect edge alignment within the finished book jacket.

The step before book trimming is the binding of the folded printing sheets. Trimming is performed either with a hydraulic book trimmer that is able to cut a whole book in one or two passes or, until the invention of hydraulic book trimmers, with a cutting press (or lying press) and plough.

Cutting principles

Knife cut principle
The book-cutting machine works with three knives and uses the knife-cut principle. The knife-cut principle operates with only one knife per edge which cuts against a rubber surface. This surface supports the cut force. The three-knife-trim is performed in one step. The block is aligned and fixed by the pressure bar. The three knives cut all edges except the spine; new machines need only one step.

Shear cut principle
The shear cut principle works with two knives – upper and bottom knife. The bottom knife is fixed and the upper knife works against the fixed one. Example of the shear cut principle is the cut of the paper web in the web offset machine and this is realized by a circular blade. To cut simple brochures (booklets) is used by a trimmer which works in two steps.

Burst cut
The third principle is the burst cut. This knife does not need a counter-acting tool. The required cut force is generated by the clamping force of the clamped paper.

See also
Book publishing
Bookbinding
Bleed (printing)

References

Print production
Book arts

Book trimming


The  is a  arboretum and botanical garden located in the southern tip of the Ocean Expo Park at Ishikawa 424, Motobu-cho, Kunigami-gun, Okinawa, Japan. It is open daily without charge.

The arboretum was established in August 1976 on the site of the 1975 Okinawa Ocean Expo, and describes itself as the only tropical and subtropical arboretum in Japan with Okinawan climate. Its mission is education and the promotion of the urban afforestation, with sample gardens including nearly 37,500 plants representing 320 species of tropical and subtropical plants. Major arboretum features include an herb garden, hedge & vine area, ground cover area, street trees, and sections for salt and wind tolerant trees, palm trees, and bushes.

There is an aquarium in the botanical garden where rainforest fish such as Arapaima and various species of Arowana, Catfish, and Freshwater Stingray are bred.

See also
 Okinawa Churaumi Aquarium (Facilities in Ocean Expo Park)
 Expo '75
 List of botanical gardens in Japan

References
 Tropical & Subtropical Arboretum Website
 Oki-Park official site
 Okinawa Tourist Information article

Arboreta in Japan
Botanical gardens in Japan
Parks and gardens in Okinawa Prefecture

Tropical & Subtropical Arboretum


Vesper Lynd is a character in several James Bond movies and in the novel Casino Royale. She is a Bond girl.

In the novel, she works for MI6 and assists Bond whilst gambling in France. She later turns out to be a double agent.

In the 1967 movie Casino Royale, she is a former MI6 agent who has an affair with a man named Evelyn Tremble. She later betrays him.

In the 2006 movie Casino Royale, she is a foreign liaison agent. She is also a double agent working for a terrorist group named Quantum, which MI6 are trying to stop. She later falls in love with Bond. She embezzles money for Quantum, but Bond does not know that. She dies when an elevator she is in fills with water.

Vesper Lynd is played by Ursula Andress in the 1967 movie and by Eva Green in 2006 movie.

Bond girls

Vesper Lynd


Earl W. Wallace (October 23, 1942 – May 12, 2018) was an American screen and television writer who began his career in the 1970s writing episodes of the hit CBS Western series Gunsmoke, one of which inspired him, his wife Pamela, and William Kelley to develop the screenplay for the 1985 film Witness.

Wallace's first submission to Gunsmoke came while he was city editor of a regional newspaper, the Thousand Oaks Acorn. He had enrolled in a screenwriting class where the assignments included the creation of an original episode of Gunsmoke. The professor submitted Wallace's teleplay to the Gunsmoke writing staff, who accepted it and ran it as an episode. They invited Wallace to submit further work and eventually offered him a regular position on their writing staff. When the show ended in its 20th season, Wallace was its head writer.

Wallace adapted the Herman Wouk novel War and Remembrance for a twelve-part miniseries broadcast by ABC. He also wrote episodes of How the West Was Won, Seven Brides for Seven Brothers, and Quinn Martin's Tales of the Unexpected, and several television movies, including Wild and Wooly, If These Walls Could Talk, A Murderous Affair: The Carolyn Warmus Story, and Rose Hill.

For his work on Witness, Wallace won the Academy Award for Best Original Screenplay, the Writers Guild of America Award for Best Original Screenplay, and the Edgar Award for Best Motion Picture Screenplay and was nominated for the Golden Globe Award for Best Screenplay and the BAFTA Award for Best Original Screenplay. He is the recipient of the Western Writers of America Spur Award for Best Television Script for How the West Was Won.

Wallace died in 2018.

References

Sources

External links

American male screenwriters
American television writers
Best Original Screenplay Academy Award winners
American male television writers
Writers Guild of America Award winners
1942 births
2018 deaths

Earl W. Wallace


The Hoagland solution is a hydroponic nutrient solution that was newly developed by Hoagland and Snyder in 1933, modified by Hoagland and Arnon in 1938, and revised by Arnon in 1950. It is one of the most popular standard artificial solution compositions for growing plants, in the scientific world at least, with more than 19,000 citations listed by Google Scholar. The Hoagland solution provides all essential elements for plant nutrition and is appropriate for supporting normal growth of a large variety of plant species.

Modifications
The solution described by Dennis Hoagland in 1933, known as Hoagland solution (0), has been modified several times, mainly to add ferric chelates to keep iron effectively in solution, and to optimize the composition and concentration of other trace elements, some of which are not generally credited with a function in plant nutrition. In Hoagland's nutrient recipes of 1938, referred to as Hoagland solution (1, 2), the number of trace elements was subsequently reduced to the generally accepted essential elements (B, Mn, Zn, Cu, Mo, Fe, and Cl). Later research confirmed that their concentrations had been adjusted for optimal plant growth.

In Arnon's revision of 1950, only one concentration (Mo 0.011 ppm) was changed compared to 1938 (Mo 0.048 ppm), while the concentration of macronutrients of the Hoagland solutions (0), (1), and (2) remained the same since 1933, with the exception of calcium (160 ppm) in solution (2). The main difference between solution (1) and solution (2) is the different use of nitrate-nitrogen and ammonium-nitrogen based stock solutions to prepare the respective Hoagland solution of interest. Accordingly, the original 1933 and the modified concentrations of 1938 and 1950 for each essential element and sodium are shown below, the calculation of the latter values being derived from Tables 1 and 2:

N 210 ppm
P 31 ppm
S 64 ppm
Cl 0.14 ppm / 0.65 ppm
B 0.11 ppm / 0.5 ppm
Na 0 ppm / 0.023 ppm / 1.2 ppm*
Mg 48.6 ppm
K 235 ppm
Ca 200 ppm / 160 ppm
Mn 0.11 ppm / 0.5 ppm
Zn 0.023 ppm / 0.05 ppm
Cu 0.014 ppm / 0.02 ppm
Mo 0.018 ppm / 0.048 ppm / 0.011 ppm
Fe 1 ppm / 5 ppm / 2.9 ppm*

Applications
Plant nutrients are usually absorbed from the soil solution. The Hoagland solution, originally intended to imitate a (nutrient-) rich soil solution, has high concentrations of N and K so it is very well suited for the development of large plants like tomato and bell pepper. For example, a half-strength macronutrient solution (1) of Hoagland can be combined with a full micronutrient solution of Long Ashton and a tenth-strength ferric EDTA solution to fertilize tomato seedlings. Due to relatively high concentrations in the aqueous stock solutions (cf. Tables 1 and 2) the Hoagland solution is very good for the growth of plants with lower nutrient demands as well, such as lettuce and aquatic plants, with the further dilution of the preparation to  or  of the modified solution.

Components
Salts, acids and complex ions to make up the Hoagland hydroponic solution formulations (1) and (2):

 Potassium nitrate, KNO3
 Calcium nitrate tetrahydrate, Ca(NO3)2•4H2O
 Magnesium sulfate heptahydrate, MgSO4•7H2O
 Potassium dihydrogen phosphate, KH2PO4 or
 Ammonium dihydrogen phosphate, (NH4)H2PO4
 Boric acid, H3BO3
 Manganese chloride tetrahydrate, MnCl2•4H2O
 Zinc sulfate heptahydrate, ZnSO4•7H2O
 Copper sulfate pentahydrate, CuSO4•5H2O
 Molybdic acid monohydrate, H2MoO4•H2O or
 Sodium molybdate dihydrate, Na2MoO4•2H2O
 Ferric tartrate or Iron(III)-EDTA− or Iron chelate (Fe-EDDHA−)

Components for Hoagland solution (1)
To prepare the stock solutions and a full Hoagland solution (1)

Components for Hoagland solution (2)
To prepare the stock solutions and a full Hoagland solution (2)

Alternatives for some components
Sprint 138 iron chelate is produced as Na-Fe-EDDHA (C18H16FeN2NaO6), while Hoagland's original solution formulations contain ferric tartrate (C12H12Fe2O18), but no sodium ions. Synthesizing a sodium-free ferric EDTA complex (C10H12FeN2O8−) in a laboratory is sometimes preferred to buying ready-made products. Variable micronutrients (e.g., Co, Ni) and rather non-essential elements (e.g., Pb, Hg) mentioned in Hoagland's 1933 publication (known as "A-Z solutions a and b") are no longer included in his later circulars. Most of these metallic elements, as well as organic compounds, are not necessary for normal plant nutrition. As an exception, there is evidence that, for example, some algae require cobalt for the synthesis of vitamin B12.

See also
Murashige and Skoog medium
Long Ashton Nutrient Solution

References

External links
 Modified composition of the Hoagland solution
 National Academy of Sciences: A Biographical Memoir of Dennis Robert Hoagland by Walter P. Kelley
 "A-Z solution", Supplementary Nutrient Solution (Solution A), according to Hoagland and Snyder (1933)
 The Hoaglands Solution for Hydroponic Cultivation

Hydroponics

Hoagland solution


Michael Lee Wesch (born June 22, 1975) is Professor of Cultural Anthropology and a University Distinguished Teaching Scholar at Kansas State University. Wesch's work also includes media ecology and the emerging field of digital ethnography, where he studies the effect of new media on human interaction.

Wesch is a cultural anthropologist and media ecologist exploring the effects of new media on human interaction. He graduated summa cum laude from the Kansas State University Anthropology Program in 1997 and returned as a faculty member in 2004 after receiving his PhD in Anthropology at the University of Virginia. There he pursued research on social and cultural change in Melanesia, focusing on the introduction of print and print-based practices like mapping and census-taking in the remote Mountain Ok region of Papua New Guinea where he lived for a total of 18 months from 1999-2003. This work inspired Wesch to examine the effects of new media more broadly, especially digital media. Also as a consequence of this trip, Dr. Wesch has gained some command of the Tok Pisin language, a primary lingua franca of Papua New Guinea.

Wesch launched the Digital Ethnography Working Group, a team of undergraduates at Kansas State University exploring human uses of digital technology. Coinciding with the launch of this group, Wesch created a short video, "Web 2.0 The Machine is Us/ing Us." Released on YouTube on January 31, 2007. In June 2008 Wesch presented An Anthropological Introduction to YouTube to the US Library of Congress. Wesch drew on the work of his students to present unique ideas and discoveries about the social impact of YouTube and socially networked media generally.

Wesch has won several awards for his work with video, including a Wired Magazine Rave Award and the John Culkin Award for Outstanding Media Praxis from the Media Ecology Association.

Wesch's videos are part of his broader efforts to pursue the possibilities of digital media to extend and transform the way ethnographies are presented. Wesch is also a multiple award-winning teacher, active in the development of innovative teaching techniques. Most notably, Wesch has developed a highly acclaimed "World Simulation" for large introductory classes in cultural anthropology. On 20 November 2008, CASE and the Carnegie Foundation for the Advancement of Teaching honored Wesch as Professor of the Year.

Currently he is the coordinator for the Peer Review of Teaching Project at Kansas State University, part of a broader nationwide consortium of universities pursuing new ways to improve and evaluate student learning. He is also working with the Educause Center for Applied Research on "The Tower and the Cloud" project, examining "the question of how higher education institutions (The Tower) may interoperate with the emerging network-based business and social paradigm (The Cloud)."

See also
 Context collapse

Further reading

References

External links
Official Page with Bio, Videos, Presentations, News, and Other Materials

Cultural anthropologists
Living people
1975 births
People from Fairbury, Nebraska
Kansas State University alumni
University of Virginia alumni
Kansas State University faculty

Michael Wesch


The Nahum Gutman Museum of Art is an art museum located in Neve Tzedek, Tel Aviv, Israel.

The Museum resides in the historical Writers' Home, which was built in 1887 and was one of the first buildings in the Neve Tzedek neighborhood. Between 1907 and 1914 the building served as HaPoel HaTzair Newspaper's hub.

The building's name arose as the place was home to several authors, including Devorah Baron, Yosef Aharonovich, Asher Beresh, Yehuda Burla, and more. During World War I the building stopped serving the purpose of housing authors, and became an ordinary residence until it was abandoned in the 1960s.

In 1992, after the inclusion of the building in the Tel Aviv Building Preservation Program, the building underwent renovation by the architect Roni Zaibert. The museum was opened in May 1998, and the artwork was donated by Nahum Gutman's family, who had wanted to perpetuate his works.

Many items from Nahum Gutman's studio were also donated, and the studio was recreated in one of the museum's rooms. The museum's first director was the curator Yoav Dagon, and today the head curator is Tali Tamir and the museum's director Roni Disenchik.

In September 2009 a new art exhibition division was opened, named after  Mori and Ireen Pargament, as well as an events hall for up to 70 people and a new gift store. The exhibitions at the museum bring together Nahum Gutman's works with other artists working in the field of contemporary art, and create dialogues between different eras and different perspectives.

In 2013, board member and lawyer Yitzhak Shviger resigned, claiming that the foundation had become "a stage for Palestinian propaganda".

See also
 List of single-artist museums

References

External links
 Website

Art museums and galleries in Israel
Biographical museums in Israel
Museums in Tel Aviv

Nahum Gutman Museum of Art


Martin Pope (born Isidore Poppick; August 22, 1918March 27, 2022) was an American physical chemist and professor at New York University.

His discoveries of ohmic contacts and research in the fields of organic insulators and semiconductors led to techniques enabling organic semiconductors to carry relatively large currents, and to convert electricity into light and vice versa.  These discoveries have had application in electrophotography, organic light-emitting diodes (OLED), photovoltaic cells, biological sensors, transistors, molecular electronics, and batteries.

For his work, Dr. Pope was awarded the Davy Medal from the Royal Society in 2006.

Biography

Martin Pope was born in 1918 to Jewish immigrants from Ukraine. The second of four sons, Pope grew up on New York's Lower East Side. He attended the City College of New York, graduating with a bachelor's degree in chemistry in 1939.

While at CCNY, Pope assisted in nuclear experiments at Columbia University and met Fermi, Schwinger, Dunning and other key figures in the development of nuclear fission.  After graduation, he served in the Army Air Force in the Pacific, where he reached the rank of first lieutenant. After the war, Pope returned home and found work at Balco Research Laboratories, where he received two patents for thin film inventions. He received his Ph.D. in 1950 from the Brooklyn Polytechnic Institute.

He joined the faculty of New York University in 1956 as a researcher in the Radiation and Solid State Physics Lab (RSSL). In 1988, he retired as professor of chemistry and director of the RSSL. He became professor emeritus, physical chemistry at NYU. He was still active in research until the final years of his life. He published his last two papers in 2003 and 2004.

Personal life and death
Pope married Lillie Pope, an educational psychologist and author, in 1946. She died in 2015.

He turned 100 in August 2018, and died on March 27, 2022, at the age of 103.

References

External links
 Martin Pope home page
 Radiation and Solid State Physics Lab photogallery

1918 births
2022 deaths
American physical chemists
Polymer scientists and engineers
Fellows of the American Physical Society
City College of New York alumni
New York University faculty
Polytechnic Institute of New York University alumni
United States Army Air Forces personnel of World War II
United States Army Air Forces officers
Jewish American scientists
People from the Lower East Side
American people of Ukrainian-Jewish descent
21st-century American Jews
21st-century American physicists
Scientists from New York City
American centenarians
Men centenarians
Military personnel from New York City

Martin Pope


Cajalco Canyon Creek is an ephemeral stream that flows through Cajalco Canyon in the Temescal Mountains of Riverside County, California, United States. It is a tributary to Temescal Wash, itself a tributary to the Santa Ana River.  Cajalco is thought to be a Hispanic spelling of the word for "quail" in the languages of the Luiseño and Cahuilla who lived in the area. The word Cajalco is an acronym- California Jalisco Land Company of Los Angeles

Course
Cajalco Canyon Creek originally flowed down the northeast face of the Gavilan Hills of the Temescal Mountains at .  It then turned northwest to take in waters from arroyos from Mead Valley and turned west down through the wide, gently sloping Cajalco Valley above Cajalco Canyon gathering waters from the Gavilan Plateau from Harford Spring Canyon at , and from other minor arroyos.  Other small arroyos descended from heights to the north.  It entered Temescal Wash at  after descending through the steep narrow gorge of the Cajalco Canyon in the lower reach of the creek.  The original course of the creek, before 1933, can be seen on the US Dept. of the Interior's 1898 topographic map of the Elsinore Quadrangle.

Lake Mathews
In the 1930s a dam was built in Cajalco Canyon, blocking the stream as part of the Colorado River Aqueduct project that created the Cajalco Reservoir, now Lake Mathews.  Now the water of the upper reach of the creek flows down through Cajalco Valley to join this reservoir at .  The lower reach below the dam still flows through what remains of Cajalco Canyon into the Temescal Wash.

References

Rivers of Riverside County, California
Tributaries of Temescal Creek
Rivers of Southern California

Cajalco Canyon Creek


The Scania-Vabis L10/L40/L51 was a series of trucks produced by Swedish automaker Scania-Vabis between 1944 and 1959.

Scania-Vabis L10
During the Second World War Scania-Vabis' entire production went to the Swedish Armed Forces and other public institutions. The company designed a new generation of trucks for post war times, when the pent-up demand for new trucks was expected to boom. The first post-war model, L10, was introduced in 1944. It was the first Scania-Vabis truck with left hand drive. The L10 Series had a four-cylinder variant of the module engine Scania-Vabis had introduced in the late 1930s, which was also built in the six- and eight cylinder versions, as petrol or diesel engine. The diesel engine in the L10 series was a pre-chamber engine. The truck could also be delivered with four-wheel drive, a version known as the F10. It had a war time chassis and military trucks were also sold with petrol engine.

Before the war, Scania-Vabis purchased many components from Germany and Great Britain, but these were now largely replaced by Swedish-made components. Unfortunately, production was in several cases started without adequate testing and those first postwar trucks suffered quality problems that cost Scania-Vabis both money and reputation to repair.

Scania-Vabis L40
At the end of 1949, Scania-Vabis introduced a direct injected diesel development of their module engine. It had been designed in collaboration with British truck manufacturer Leyland Motors. With the new engine, the four-cylinder truck got its name changed to L40. Otherwise the truck was mostly unchanged. In early 1950 there were also a small number of the four-wheel drive F40 built, before that model disappeared because of low market demand. In 1951 the old fashioned non-synchro four-speed gear box was replaced by a synchronized five-speed transmission.

Scania-Vabis L51 Drabant
In the spring of 1953 the final development of Scania-Vabis' module engines were introduced, with larger displacement. The four-cylinder truck was now called L51 Drabant, with a payload capacity of 5.5 to 6 tonnes. It was also the first Scania-Vabis truck with a proper name.

Engines

Gallery

References

External links

 Scania Group - history
 Swedish brass cars - picture gallery

L10
Vehicles introduced in 1944

Scania-Vabis L10


- N. T. Rama Rao Jr., also known as Jr NTR or Tarak, is an Indian actor who mainly works in Telugu cinema. He is the grandson of the legendary actor and former Chief Minister of Andhra Pradesh, N. T. Rama Rao Sr. He has won several awards, including two Filmfare Awards, two Nandi Awards, and four CineMAA Awards. He has also been featured in Forbes India Celebrity 100 list since 2012¹.
- Rama Rao Jr. started his acting career as a child artist in films such as Brahmarshi Viswamitra (1991) and Ramayanam (1997), the latter winning the National Film Award for Best Children's Film. He made his debut as a lead actor with Ninnu Choodalani (2001) and rose to fame with Student No. 1 (2001) and Aadi (2002). He established himself as a leading actor with films such as Simhadri (2003), Yamadonga (2007), Adhurs (2010), Brindavanam (2010), Baadshah (2013), Temper (2015), Nannaku Prematho (2016), Janatha Garage (2016), Jai Lava Kusa (2017), Aravinda Sametha Veera Raghava (2018), and RRR (2022).
- Rama Rao Jr. is also known for his television work. He hosted the first season of the Telugu reality show Bigg Boss on Star Maa in 2017. He is currently hosting the fifth season of Evaru Meelo Koteeswarulu on Gemini TV, which is the Telugu version of Who Wants to Be a Millionaire? He is also a trained Kuchipudi dancer and a playback singer who has sung several songs for his films.

N. T. Rama Rao Jr.


Heinu Leima is the female personification and the divinity of fruitful abundance in ancient Meitei mythology and religion. She is the goddess of fruit trees, gardens and orchards. She watches over and protects fruit trees and cares for their cultivation. The words, "Heinu" means "fruit lady" and "Leima" means "queen" in the Ancient Meitei language. She is mentioned in the Phouoibi Waron, one of the ancient Puya (Meitei texts), as one of the goddesses who helped Phouoibi to find her quests for love.

Meitei gods and goddesses
Leima

Heinu Leima