Control of column influence on the wide range pH gradient in ion-exchange chromatography

Summary A method for optimization of the mobile phase composition in ion exchange chromatography with a wide range external pH gradient (approx. over 5 pH units) has been formulated. It is shown that programming of various wide range pH profiles which are not impaired by buffer interactions of the mobile phase with sorbent is possible. Utilization of the wide range external pH gradient in cation-exchange chromatography of bovine haemoglobin is also demonstrated.     

Dually Activated Organo- and Nano-cocatalyzed Synthesis of Coumarin Derivatives

A wide range of substituted coumarin derivatives were synthesized by refluxing in acetonitrile, ethyl acetoacetate, and ethyl benzoyl acetate with a wide range of structurally diverse phenol derivatives within a short reaction time with a catalytic combination of pyridine dicarboxylic acid as organocatalyst and nanocrystalline ZnO.     

Synthesis of symmetrical diaryl ethers from arylboronic acids mediated by copper(II) acetate

Copper promoted generation of phenols in situ through arylation of water and their subsequent arylation with arylboronic acids affords a wide range of symmetrical diaryl ethers in good to high yield. The reaction is rapid, mild, convenient and tolerant of a wide range of functionalities on the arylboronic acid.     

Comparison of Neural Networks and Theoretical Correction Models

In x-ray fluorescence spectrometry, matrix effects have to be corrected. The empiric equations, the theoretical coefficients and the fundamental parameters can be applied in the purpose. The classical matrix correction models include mainly Lachance-Trail,Rousseau, De Jongh, Claisse-Quentin, COLA algorithms,etc. The good results can be obtained by using a number of standards or the theoretical Alpha coefficients if the range of component concentrations in samples is not very wide. When unknown samples with a wide range of concentrations are predicted, a recalculation process of the theoretical Alpha coefficients has to be made. In addition, a spline function may be chosen to split wide range in several segments.     

反相液相色谱的双柱规律

本文在液相色谱保留值方程ln κ′=A B·C_B C·InC_B的基础上,在很宽的浓度范围内考察了反相液相色谱的双柱规律,根据这个方法,在一个柱上只要做一次先行实验,就可在较宽的浓度范围内把一个柱上的k’转移到另一柱上去。     

Combining low and high mass ion accumulation for enhancing shotgun proteome analysis by accurate mass measurement

A simple procedure is described that increases sensitivity and dynamic range for the analysis of a proteome batch digest by FT-ICR mass spectrometry. Ions at the low and high mass ranges are preferentially collected using two different sets of tuning conditions. By combing data collected using tuning conditions that favor low mass (m/z < 2000) and high mass (m/z > 2000) ions, 277 proteins are identified for a whole cell lysate of Methanococcus maripaludis in a single HPLC-MALDI FT-ICR mass spectrometry experiment, a 70% improvement compared with previous analyses using a wide mass range acquisition. This procedure improves the detection of low abundance ions and thereby increases the range of proteins that are observed. Because the observed mass range is effectively narrower for each spectrum, mass calibration is more accurate than for the standard method that provides a wide range of masses. The trap plate potential on the analyzer cell may be set to a higher value than used for wide mass range measurements, increasing the ion capacity of the analyzer cell and extending the dynamic range, while still maintaining mass accuracy.     

FRET- and PET-based sensing in a single material: expanding the dynamic range of an ultra-sensitive nitroaromatic explosives assay

A polyethylenimine polymer derivatized with pyrene moieties suitable for the fluorescence-based detection of nitroaromatic explosives (NAC) in aqueous systems is described. The system exhibits an exceptionally wide dynamic sensing range of 7 orders of magnitude (from 33 ppt to 225 ppm TNT or Tetryl). This broad range was achieved by the combination of FRET and PET sensing mechanisms in a single material. The sensing material is suitable for a paper strip assay. Simplicity, selectivity, and the wide dynamic range suggest this material for explosives detection in the field.     

Effect of the degree of extension on the phase composition and tendency toward mesomorphism of UHMWPE in gel-spun oriented fibers

Structural transformations of UHMWPE-based fibers prepared by orientational drawing have been studied by the combination of SAXS and WAXS methods, photo- and diffractometry, and isometric DSC measurements in a wide temperature range. A sequence of phase transformations and other structural changes has been followed and identified during the orientational deformation of the fibers in a wide range of draw ratios from 1 to 85 within the temperature interval from room temperature to the melting temperature of the polymer.     

Isochoric heat capacity and the <Emphasis Type="Italic">T</Emphasis>-ρ dependence of refrigerants of a propane series

An analysis of the principles of thermodynamic properties of refrigerants of a propane series is per- formed over a wide range of state parameters, including the critical range.     

Silver-catalyzed highly efficient synthesis of pyrido[1,2-a]pyrimidin-4-ones from 2-aminopyridines and alkynoates

Pyrimidinone is one of the important nitrogen containing heterocycles due to their wide range of bioactivities. An efficient silver-catalyzed intermolecular cyclization of 2-aminopyridines with various alkynoates has been developed. 2-Substituted 4H-pyrido[1,2-a]pyrimidin-4-ones containing a wide range of functional groups are synthesized in the standard conditions. This transformation is conducted under convenient conditions and affords products in good yields.     

Expedient synthesis of biologically important sulfonylmethyl pyrimidines

Two novel synthetic strategies that allow rapid diversification of the sulfone moiety in sulfonylmethyl pyrimidines, a class of compounds with a wide range of biological activity, which are of interest in a wide variety of drug discovery programmes, are described.     

Influence of Short-Chain Alcohols on the Micellization Parameters of Sodium Dodecyl Sulfate (SDS)

The influence of short-chain alcohol on the aggregation behavior of Sodium Dodecyl Sulfate (SDS) is investigated within a wide range of alcohol concentration by potentiometric technique. It is observed that aggregation behavior of SDS is a function of alcohol concentration. Variation of micellization parameters are studied in a wide range of alcohol concentration and the trend of changing of micellization parameters have been investigated. The variations of micellization parameters show several regularities. Finally, the relationships between these regularities and alcohol-surfactant interactions have been explained.     

Parallel tempering simulations of the 13-center Lennard-Jones dipole-dipole cluster (muD=0-->0.5 a.u.)

We investigate the thermodynamic behavior of the thirteen center uniform Lennard-Jones dipole-dipole cluster [(LJDD)(13)] for a wide range of dipole moment strengths. We find a relatively wide range of potential parameters where solid-solid coexistence manifests itself. Using structural characterization methods we determine the shape of the few isomers that contribute to the solid-solid coexistence region. The thermal distributions of the size of the net dipole moment are broad even at the coldest temperatures of the simulation where the (LJDD)(13) cluster is solid.     

Determination of trace levels of oxygen by gamma-photon activation

A sensitive activation technique for the determination of trace levels of oxygen in a wide range of materials is described with particular emphasis on the γ-irradiation facilities at AERE Harwell and experience of the use of the technique over a number of years. Procedures for removing surface oxygen contamination prior to determination of bulk oxygen concentrations are given, together with details of the radiochemical separation procedures used for a wide range of materials, and examples of the results obtained.     

Molybdenum-mediated synthesis of quinazolin-4(3H)-ones via cyclocarbonylation using microwave irradiation

A new, efficient and practical synthesis of quinazolin-4(3H)-ones is reported via molybdenum-mediated cyclocarbonylation using microwave irradiation. These methods allow access to a wide range of quinazolin-4(3H)-ones in reasonable yields without the need for gaseous carbon monoxide and palladium catalysts. A range of reactions illustrating the wide scope of this chemistry was carried out and all proceeded in reasonable yields.     

Structure-property correlations of non-starch food polysaccharides

Gums, the majority of which are polysaccharides, have a wide variety of chemical structures, a range of physicochemical properties, and impart a range of functionalities to foodstuffs and prepared foods.     

Pouring wide-range immobilized pH gradient gels with a window of extremely flattened slope

A gradient mixing device has been designed to pour polyacrylamide gels with a wide-range immobilized pH gradient including a "window" of extremely flattened slope. The device consists of an IBM-compatible personal computer controlling 8 step-motor-driven burettes, with four producing a density gradient from glycerol and delivering acrylamides and catalysts for gel polymerization, two delivering Immobilines for a wide-range pH gradient and the other two burettes responsible for the delivery of Immobilines for a partial pH range inside the wide range. The effect on a complex separation pattern of proteins with a wide range of pI is that resolution can be increased reproducibly to any reasonable extent at any location of the separation pattern.     

Some features of luminescent properties of PbS suspensions,stabilized by high‐molecular polyvinylpyrrolidone

The results of the investigations of optical and luminescent properties of PbS suspensions stabilized by high‐molecular polyvinylpyrrolidone are described. Suspensions prepared by liquid colloidal method from sodium sulfide and lead nitrate demonstrate strong luminescence in near infrared spectral range at the excitation by visual light with different wavelengths. It was proposed that Förster resonant energy transfer plays the important role in luminescence properties of closed packed PbS particles. The model, which describes the observed luminescent properties of the suspensions PbS‐stabilized high‐molecular polymer, is proposed. The combination of very wide spectral range of excitation of the luminescence with rather narrow range of light radiation in near infrared spectral range determine wide perspectives of the materials in solar luminescent concentrators and photodetectors. Copyright © 2015 John Wiley & Sons, Ltd.     

Cobalt(II)-selective membrane electrode based on a recently synthesized benzo-substituted macrocyclic diamide.

A PVC-membrane electrode based on a recently synthesized 18-membered macrocyclic diamide is presented. The electrode reveals a Nernstian potentiometric response for Co2+ over a wide concentration range (2.0 x 10(-6)-1.0 x 10(-2) M). The electrode has a response time of about 10 s and can be used for at least 2 months without any divergence. The proposed sensor revealed very good selectivities for Co2+ over a wide variety of other metal ions, and could be used over a wide pH range (3.0-8.0). The detection limit of the sensor is 6.0 x 10(-7) M. It was successfully applied to the direct determination and potentiometric titration of cobalt ion.     

Nanoscale molecular patterns fabricated by using scanning near-field optical lithography

Nanometer-scale patterns have been created in self-assembled monolayers by using a scanning near-field optical microscope coupled to an ultra-violet laser emitting light at a wavelength of 244 nm. Sharp, chemically well-defined features with dimensions as small as 40 nm have been created routinely, and on occasions line widths of 25 nm (lambda/10) have been achieved. Because of the wide range of photochemical methods available for surface derivatization, this approach promises to provide a flexible and versatile route to the generation of molecular and biological nanostructures for a wide range of applications.