Dynamics Study of the Influence of Temperature on Konjac Glucomannan Saline Solution’s Viscosity

Molecular dynamics (MD) method is adopted to simulate the conformation variations of konjac glucomannan (KGM) saline solution at different temperatures, and structurally analyze the trends and reasons of viscosity change in KGM saline solution with temperature. The experimental results have been analyzed to find out that the sum of formative hydrogen bonds decreases with the rise of temperature and the amount of intramolecular hydrogen bonds suddenly increases at 323 K. Besides, in terms of molecular orbital data obtained from simulation, we can know that hydrogen bonding energy also decreases with the rise of temperature. Therefore, we can predict the viscosity of KGM saline solution decreases gradually when rising the temperature.     

Study on the quantitative structureactivity relation-ship of C-10 substituted artemisinin (QHS)’s derivatives using rough set theory

The structure-activity relationship study of C-10 substituted artemisinin (QHS) derivatives that are used as antimalarial was performed with the RS (rough sets) method. An RS process is a concise nonlinear process, and it has broad application foreground in the data mining of nonlinear life courses. In this work, initially the parameters of C-10 substituted QHS’s derivatives were computed with the quantum chemistry method, and the information table was constructed from the parameters (condition attributes) and biological activity (decision attributes). Based on the analysis of rough set theory, the core and reduction of attributes sets were obtained. Then the decision rules were extracted and the struc-ture-activity relationship was analyzed. As a nonlinear system, RS theory can extract the special rela-tion in the database. It has the advantage of being nonlinear over multiple linear regression (MLR), principal component analysis (PCA), partial least square (PLS), etc., and the advantage of obtaining results with unambiguous physical meanings over artificial neuron networks (ANNs), etc. The result obtained in this study is instructive to the study of pharmacodynamics, resistance mechanism of QHS and development of QHS’s derivatives.     

Study on the Vortex of the Qinghai-Xizang (Tibet) Plateau in Summer

In this paper an ideal model for the formation and development of the Qinghai-Xizang Plateau vortex is presented by a large number of statistical data and typical case studies. It points out that the Plateau vortex is shallow and thermal originated from a strong heat source near the surface of the west of the Plateau. Then moving eastward , it develops and becomes stronger and thicker with larger upward vertical velocity, and causes great precipitation in the middle Plateau. But at this time the heat source in the vortex becomes weaker, and even the heat sink occurs near the surface. Consequently, it disappears in a cold trough with a strong heat sink in the east of the Plateau. The heat source (sink) is mainly determined by the vertical eddy flux convergence (divergence) of the sensible heat caused by the cumulus convection and turbu-lance. Both the nonuniform heating (cooling) at the surface and the convergence (divergence) of the eddy kinetic energy coact and play an important role in the genesis (di     

Effect of Chemical Modification of the Tetrapyrrole Macrocycle Structure on the Spectral,Acid–Base,and Complexing Properties of tert-Butyl-Substituted Porphyrazines

Russian Journal of Organic Chemistry - The effect of chemical modification of the tetrapyrrole macrocycle structure on the spectral, acid–base, and complexing properties of...     

Study on the Synthesis of Di(3,4-methyl) Benzylidene Sorbitol

Di (3,4-methyl) benzylidene sorbitol (briefly referred as “ DMDBS ”), used as transparency nucleating agent in crystallinity polyolefin kind resin, can dramaticly reduce the haze of plastic products, improving their quality in transparency, resin’s rigidity, heat resistant temperature and modulus of bending. DMDBS, having these characteristics, has been widely used as polyolefin processing auxiliary. With the presence of hydrophobicity organic solvent and lower alcohol, the nucleating ag…     

Two-Photon Solvatochromism II: Experimental and Theoretical Study of Solvent Effects on the Two-Photon Absorption Spectrum of Reichardt’s Dye

In this study, we report on the influence of solvent on the two-photon absorption (2PA) spectra of Reichardt’s dye (RD). The measurement of 2PA cross-sections is performed for three solvents (chloroform, dimethyl formamide, and dimethyl sulfoxide) using the Z-scan technique. The key finding of this study is the observation that the cross-section, corresponding to the 2PA of the intramolecular charge-transfer state, diminishes substantially upon increasing the solvent polarity. To unravel the solvent dependence of the 2PA cross-section, the electronic structure of RD is determined using a hybrid quantum mechanics/molecular mechanics (QM/MM) approach, in which polarization between the solute and solvent is taken into account by using a self-consistent scheme in the solvent polarization. The two-state approximation proves to be adequate for the studied system, and allowed the observed solvent-polarity-induced decrease of the 2PA cross-section to be related to the decrease of the transition moment and the increase in the excitation energy.     

A nonparametric scaling equation of state,developed on the basis of the Migdal’s phenomenological theory and Benedek’s hypothesis

A new nonparametric scaling equation with density and temperature as variables is proposed using the phenomenological theory of critical phenomena and the experimentally confirmed Benedek’s hypothesis, on the basis of which we assume that the behavior of a number of thermodynamic functions for the critical and near-critical isochores in the neighborhood of an asymptotic critical point is similar. In comparison to Scofield’s linear model (LM), the proposed scale equation is not inferior to known nonparametric equations of the same type; in contrast to the latter, however, its physical grounds are just as valid as the LM equation.     

Lavoisier’s “Reflections on phlogiston” II: on the nature of heat

Having refuted the phlogiston theory, Lavoisier uses this second portion of his essay to expound his new theory of combustion, based on the oxygen principle. He gives a mechanistic account of thermodynamic phenomena in terms of a subtle fluid (not yet named “caloric”) and its ability to penetrate porous bodies. He uses this hypothetical fluid to explain volume changes, heat capacity and latent heat. Beyond the three types of combustion that he distinguishes and defines, Lavoisier also explains other chemical sources of heat, such as the heat of solution.     

Influence of the Length of the Alanine Spacer on the Acidic–Basic Properties of the Ac–Lys–(Ala) n –Lys–NH2 Peptides (n?=?0, 1, 2, …, 5)

By using the potentiometric titration method, we have determined the pK _a values of the two terminal lysine groups in six alanine-based peptides differing in the length of the alanine chain: Ac?CLys?CLys?CNH₂ (KK), Ac?CLys?CAla?CLys?CNH₂ (KAK), Ac?CLys?CAla?CAla?CLys?CNH₂ (KAK2), Ac?CLys?CAla?CAla?CAla?CLys?CNH₂ (KAK3), Ac?CLys?CAla?CAla?CAla?CAla?CLys?CNH₂ (KAK4), and Ac?CLys?CAla?CAla?CAla?CAla?CAla?CLys?CNH₂ (KAK5) in aqueous solution. For each compound, the model of two stepwise acid?Cbase equilibria was fitted to the potentiometric-titration data. As expected, the pK _a values of the lysine groups increase with increasing length of the alanine spacer, which means that the influence of the electrostatic field between one charged group on the other decreases with increasing length of the alanine spacer. However, for KAK3, the pK _a1 value (8.20) is unusually small and pK _a2 (11.41) is remarkably greater than pK _a1, suggesting that the two groups are close to each other and, in turn, that a chain-reversal conformation is present for this peptide. Starting with KAK3, the differences between pK _a1 and pK _a2 decrease; however, for the longest peptide (KAK5), the values of pK _a1 and pK _a2 still differ by about 1 unit, i.e., by more than the value of log₁₀ (4)?=?0.60 that is a limiting value for the pK _a difference of dicarboxylic acids with increasing methylene-spacer length. Consequently, some interactions between the two charged groups are present and, in turn, a bent shape occurs even for the longest of the peptides studied.     

Structural Characterization of Missense Mutations Using High Resolution Mass Spectrometry: A Case Study of the Parkinson’s-Related Protein,DJ-1

Missense mutations that lead to the expression of mutant proteins carrying single amino acid substitutions are the cause of numerous diseases. Unlike gene lesions, insertions, deletions, nonsense mutations, or modified RNA splicing, which affect the length of a polypeptide, or determine whether a polypeptide is translated at all, missense mutations exert more subtle effects on protein structure, which are often difficult to evaluate. Here, we took advantage of the spectral resolution afforded by the EMR Orbitrap platform, to generate a mass spectrometry-based approach relying on simultaneous measurements of the wild-type protein and the missense variants. This approach not only considerably shortens the analysis time due to the concurrent acquisition but, more importantly, enables direct comparisons between the wild-type protein and the variants, allowing identification of even subtle structural changes. We demonstrate our approach using the Parkinson’s-associated protein, DJ-1. Together with the wild-type protein, we examined two missense mutants, DJ-1_A104T and DJ-1_D149A, which lead to early-onset familial Parkinson’s disease. Gas-phase, thermal, and chemical stability assays indicate clear alterations in the conformational stability of the two mutants: the structural stability of DJ-1_D149A is reduced, whereas that of DJ-1_A104T is enhanced. Overall, we anticipate that the methodology presented here will be applicable to numerous other missense mutants, promoting the structural investigations of multiple variants of the same protein.

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Ab initio Study on the Interaction of La (Ⅲ) with Adrenaline

IntroductionInrecentyears,thebiologlcaIeffectsofrareearthshavcbeendsdsedestensiveyinChina.IthasbecnfoundthatrareearthsshowintcreedngneuralandendocrineeffeCtlll.Thermdyontheintcractionofrareearth8withhormoncisveryhoportanttoclariopgthencuralandendocrinceffecofrareearth8anditsmeckanism.Adrenalineisavitalkindofhormone.ThermdiesoncomplexesofmstaiionswithadrenalinhavebecnrePOrted12'4l.Bowever,whichgroupofadrenalinescrvesasdonorhasbeenund6rcoatmersyforalongtimc.Thus,theinteractionofLa(III)witba…     

Study of the Electrochemiluminescence Based on the Reaction of p-Hydroxyphenylpyruvic Acid with Tris(2,2'-bipyridine)ruthenium(Ⅱ)

p-hydroxyphenylpyruvic acid (pHPP) is an important intermediate in the metabolism of tyrosine. Under normal circumstances pHPF is readily converted to 2,5-dihydroxyphenylacetic acid by p-hydroxy-phenylpyruvate oxidase and the levels of pHPP encountered in blood and urine are extremely low. However, in a few individuals suffering from a congenital metabolic defect known as tyrosinemia, the oxidase is not available which leads to dramatic elevation of pHPP levels in blood and urine^[1]. Therefore, a selective and sensitive method for measuring pHPT is very useful for the diagnosis and treatment of such disease. In this paper the electrochemiluminescence(ECL) based on the reaction of pHPP with tris(2,2'-bipyridine)ruthenium(Ⅱ)[Ru(bpy)₃²⁺] in a flow injection system has been studied and a sensitive ECL method has been developed to detect pHPP in aqueous solution.     

Based on the Second Virial Coefficient (A2) to Study Effect of the Synergistic Action of Solvent and External Electric Field on the Solution Behavior and Film’s Condensed State Structure

Chinese Journal of Polymer Science - The solventnatures are crucial to deeply reveal solution behavior of macromolecular chains, physical essence of condensed state structures formation of the film...     

The impact of measurement uncertainty on the producer’s and user’s risks, on classification and conformity assessment: an example based on tests on some construction products

The reliability of test results and subsequent classification statements or product certification depend on the variability of the product’s properties and on the validity of the test procedures used. With an emphasis on measurement uncertainty, producer’s and user’s risks as well as probabilities of conformance, conformity and classification are calculated exemplarily for two requirements for mineral aggregates used in construction. An important methodological basis is an international draft document on measurement uncertainty in conformity assessment. The mathematical instruments given are applied and further developed to a risk scenario for product classification. The results from a classification point of view show that the reliability of test results for acid-soluble sulphates is mostly acceptable and both the producer’s and user’s risks are quite small. In contrast, the magnesium sulphate index test produces results which are hardly usable for classification and certification purposes or for risk management in production. Product certification bodies should generally have an appropriate approach when dealing with results where precision data are poor.     

Effects of Hydrogen Bonding on the Transition Properties of Ethanol–Water Clusters: A TD-DFT Study

In this work, time-dependent density functional theory method was used to study the electronic transitions of hydrogen-bonded ethanol–water complexes Dimer-I, Dimer-II and Trimer. The intermolecular hydrogen bonds H₁···O₁ and O···H₂ were demonstrated by the optimized geometric structures of the three hydrogen-bonded ethanol–water complexes. It is demonstrated that the S₁-state electronic transitions for ethanol monomer and the hydrogen-bonded complex Dimer-I (through HB-I) should be of LE nature on the ethanol molecule, while those of complexes Dimer-II and Trimer should be of CT character from the hydrogen-bonded water molecule (through HB-II) to the ethanol moiety. The different electronic transition types should be the reasons for the tiny redshift of the S₁-state electronic energy for Dimer-I and the large blueshifts for Dimer-II and the Trimer compared with that of the ethanol monomer.     

A Density Functional Theory Study on the Adsorption of CN on Ni(111) Surface

1 INTRODUCTION Cyanide, CN, is an important free-radical mole-cule of one carbon chemistry, organic chemistry, free-radical chemistry and cosmochemistry. And the im-portant industrial processes, such as the Andrussovreaction, depend on the reactivity of CN bond[1]. Thechemistry of cyanide is also important in the surfacechemistry of a number of C- and N-containing sys-tems[1, . During the past decade, the adsorption of 2]CN and CN-containing molecules on transition metalsurfa…     

Formation of Diazepam–Lanthanides(III) Complexes in the 50–50 Volume % Ethanol–Water Solvent System and Study of the Effect of Temperature on the Complex Formation Constants

Diazepam (7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one) is an important derivative of the 1,4-benzodiazepine compound commercially distributed as Valium. The complex formation constants of diazepam with some light lanthanide(III) metal ions have been studied by potentiometric measurements. All titrations were performed in 50–50% (volume/volume) ethanol–water solvent mixtures at constant ionic strength (0.10 mol⋅dm⁻³). The ionic strength was maintained by using sodium perchlorate. The complex formation constants were determined at 25.00, 35.00 and 45.00 °C. With increasing temperature, a decrease was observed in the protonation constant (pK) of diazepam.     

Study on a Fluorometric Method for the Determination of Protein in Serum Using Quercetin‐Lanthanum (III)‐Sodium Dodecyl Benzene Sulfonate‐Protein System

Abstract

It was found that the fluorescence intensity of lanthanum (III) (La³⁺)‐quercetin (Qu) complex is greatly enhanced by proteins in the presence of sodium dodecyl benzene sulfonate (SDBS). Based on this finding, a new fluorimetric method for the determination of proteins was developed. Under optimum conditions, the enhanced intensity of fluorescence is in proportion to the concentration of proteins in the range of 2.5×10^?8 to 1.0×10^?5 g/mL for bovine serum albumin (BSA), 5.0×10^?8 to 1.5×10^?5 g/mL for human serum albumin (HSA), and 1.0×10^?7 to 1.5×10^?5 g/mL for egg albumin (EA). Their detection limits (S/N=3) are 5.0×10^?9 g/mL, 7.0×10^?9 g/mL, and 2.1×10^?8 g/mL, respectively. The interaction mechanism was also studied.     

Numerical Study of Jet–Target Interaction: Influence of Dielectric Permittivity on the Electric Field Experienced by the Target

Plasma Chemistry and Plasma Processing - This work presents a study of the influence of dielectric permittivity on the interaction between a positive pulsed He plasma jet and a 0.5 mm-thick...