Fourier transform infrared and raman spectra, vibrational assignment and ab initio calculations of terephthalic acid and related compounds

The Fourier transform infrared and Raman spectra of solid terephthalic acid, p-C6H4(COOH)2, have been recorded, and the Fourier transform Raman spectra for the terephthalate anion were measured. The wavenumbers for the band positions have been calculated in order to assign them. Moller-Plesset (MP2) and Density functional theory (DFT) calculations have been carried out with Huzinaga-Dunning basis sets (DZV). Also, a normal coordinate analysis through the Wilson-El'yashevich method was performed. The differences between the calculated ab initio spectra and the spectra of the solid phase have been interpreted with respect to the different C(2h) and C(i) local symmetry in the gas and in the solid phase, respectively, and considering also the formation of long-chains of terephthalic acid in the solid phase. In spite to the absence of experimental data for the cis conformation, calculations have been carried out and structural parameters and infrared intensities have been evaluated for the trans and cis conformations of terephthalic acid.     

Structural and functional characterisation of a biohybrid material based on acetylcholinesterase and layered double hydroxides

This work describes the use of layered double hydroxides (LDHs) for the immobilisation of acetylcholinesterase (AChE) on insulator/semiconductor solid supports. Different LDHs have been synthesised by a co-precipitation method. Afterwards, biohybrid materials based on AChE-LDH mixtures have been produced using wild and recombinant enzymes. Spectroscopic techniques have confirmed the LDH phase identity and the links created between the LDH and AChE. Spectrophotometric assays have demonstrated that most of the biohybrid materials are functional and stable. Several configurations have been used for AChE immobilisation. The highest catalytic responses have been observed when using wild enzyme and immobilising AChE-LDH mixtures on LDHs previously deposited on the solid supports. LDHs have been demonstrated to be suitable host matrices for AChE immobilisation on electrodes for the subsequent development of electrochemical biosensors.     

Vibrational spectra and normal mode analysis of aceheptylene and 3,5,8,10-tetramethylaceheptylene

The infrared and Raman spectra of aceheptylene and 3,5,8,10-tetramethylaceheptylene have been recorded, and the normal mode analyses have been performed with a force field which has been modified for nonbenzenoid aromatic molecules. On this basis, the fundamental frequencies have been assigned. Comparison of the vibrational spectra for the two molecules has served as an internal method of making assignments. The agreement between calculated and observed values for both molecules is satisfactory.     

Spectra and structure of silicon compounds. XVII Raman and infrared spectra and vibrational assignment for hexamethyldisilane and ab initio calculations for disilane and hexamethyldisilane

The IR spectra of gaseous and solid hexamethyldisilane between 4000 and 25 cm⁻¹ and the far-IR spectrum of the liquids from 450 to 25 cm⁻¹ have been recorded. The Raman spectra have been recorded from 3500 to 10 cm⁻¹ for all three physical phases. Assisted by ab initio calculations, the vibrational spectrum of hexamethyldisilane has been assigned under D_3d symmetry and the results of a normal coordinate analysis are discussed. No spectral features indicative of free internal rotation have been observed. Gradient ab initio calculations have been carried out for the disilane and hexamethyldisilane molecules using different types of basis sets. The structural parameters, rotational constants, unscaled and scaled frequencies and harmonic force constants have been reported for both disilane and hexamethyldisilane.     

Synthesis and Antitubercular,Antimicrobial, and Hemolytic Activity of Methyl D-Glucopyranuronate and Its Simplest Derivatives

Methyl glucuronate and some of its simplest derivatives have been synthesized, and their antitubercular, antimicrobial, and hemolytic activities have been studied. The simplest derivatives of glucuronic acid have been shown for the first time to exhibit a high antitubercular activity which is comparable with the activity of isoniazid.     

Selective N-terminal modification of peptides and proteins: Recent progresses and applications

Numerous strategies for linking desired chemical probes with target peptides and proteins have been developed and applied in the field of biological chemistry. Approaches for site-specific modification of native amino acid residues in test tubes and biological contexts represent novel biological tools for understanding the role of peptides and proteins. Selective N-terminal modification strategies have been broadly studied especially in the last 10 years, as N-terminal positions are typically so...     

DFT and Ab initio computational study on the reactivity sites of the GABA and its agonists,such as CACA,TACA, DABA,and muscimol: In the gas phase and dielectric media

The reactive behavior of GABA and its agonist molecules have been investigated using B3LYP hybrid density functional method at the 6‐311++G** basis set level, in the gas phase and dielectric media. The calculations have been performed to obtain optimized geometries, relative energies, net atomic charges, HOMO, and LUMO energies. Solvent effects have been analyzed using isodensity polarized continuum model (IPCM) for four different solvents, which are chloroform, ethanol, DMSO, and H₂O. The results have suggested that both the amino group and carboxyl group have been two of the most important active site for interactions between all compounds and their receptors. In addition they have suggested that the amino group reflects the difference in biological activity for each all molecules. The structures of these agonists have provided an essential foundation for subsequent structure‐activity analysis of ligand binding at GABA receptors, neuronal uptake inhibitors and transporters. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Guanidine methacrylate and methacryloyl guanidine hydrochloride: Synthesis and polymerization

New methods for the preparation of guanidine methacrylate, methacryloyl guanidine, and its hydrochloride have been proposed, and the physicochemical characteristics of the products have been studied. A number of kinetic parameters of the radical polymerization of these monomers have been determined (the rate and the rate constant in the initial section as well as the order of the reaction rate with respect to the concentration of the initiator for methacryloyl guanidine hydrochloride). It has been found that the classical general rules are followed: The conversion increases with an increase in temperature, while the characteristic viscosity decreases. The main NMR spectroscopic parameters of polymethacryloyl guanidine hydrochloride have been determined. According to preliminary biological tests, polymers have sufficiently high bactericidal activity and can be used as stand-alone biocidal preparations or as functional additives in composite materials.     

Pyrene‐fused Acenes and Azaacenes: Synthesis and Applications

In this account, the synthesis and applications of pyrene‐fused acenes, as well as pyrene‐fused azaacenes, have been carefully reviewed. Moreover, the synthetic methods involving two key synthons (different lengths of dienes and ynes) have been included. Furthermore, the “clean reaction” strategy has been introduced for the preparation of pyrene‐fused acenes with a single terminal‐pyrene unit from tetracene to octacene, as well as for the synthesis of pyrene‐fused octatwistacenes and nonatwistacenes with double terminal‐pyrene units. Similarly, the synthons and the synthetic methods for pyrene‐fused azaacenes have also been summarized. The applications of pyrene‐fused acenes and pyrene‐fused azaacenes have been included.     

福尔马林固定石蜡包埋组织切片蛋白质组分析方法与应用研究进展

福尔马林固定石蜡包埋(Formalin-fixed and paraffin-embedding,FFPE)是最常见的临床组织保存技术,FFPE组织具有标准化的制备流程、易于存储、标本量大、包含较完整的临床回顾性信息等特点,而成为疾病生物标志物发掘的良好载体。近年来,基于临床FFPE组织的特点,发展了系列蛋白质组学研究方法,包括样本制备、消解、分离到蛋白质质谱鉴定等多个领域,总体呈现出微量、高灵敏度、高通量的技术特点,并已成功用于肿瘤精准医学等临床蛋白质组研究。该综述将对FFPE组织切片样本的蛋白质组学方法,以及其在肿瘤研究中的应用进行概述,从而为临床精准医学蛋白质组学的研究提供借鉴思路。     

Magnetism and microfluidics

Magnetic forces are now being utilised in an amazing variety of microfluidic applications. Magnetohydrodynamic flow has been applied to the pumping of fluids through microchannels. Magnetic materials such as ferrofluids or magnetically doped PDMS have been used as valves. Magnetic microparticles have been employed for mixing of fluid streams. Magnetic particles have also been used as solid supports for bioreactions in microchannels. Trapping and transport of single cells are being investigated and recently, advances have been made towards the detection of magnetic material on-chip. The aim of this review is to introduce and discuss the various developments within the field of magnetism and microfluidics.     

Preparation and testing for homogeneity of spiked strawberry and cabbage candidate reference materials

Strawberry and cabbage candidate reference materials (RMs) have been prepared by our laboratory during 1992–1993. Fresh materials have been homogenized and spiked with known concentrations of pesticides representing compounds commonly used for strawberries and cabbages. The candidate RMs have been then freeze-dried, homogenized, bottled under a stream of nitrogen and stored frozen at –20°C. Homogeneity and stability of the candidate RMs have been studied during the storage period. Homogeneity of the candidate RMs for 5 g samples has been within 10%. Homogeneity and stability studies have been carried out using the conventional multiresidue method of Luke et al. [1]. Instrumental analysis have been performed by gas chromatography mass spectrometry (GC-MS) employing selected ion monitoring (SIM).     

Electron propagator and coupled-cluster calculations on the photoelectron spectra of thiouracil and dithiouracil anions

Electron affinities, vertical electron detachment energies, and isomerization energies of 4-thiouracil, 2-thiouracil, and 2,4-dithiouracil and their valence anions have been calculated with ab initio electron propagator and other many-body methods. Anions in which protons have been transferred to the C5 from the N1 or N3 ring positions have been considered, but the canonical forms are most stable for the 4-thiouracil and 2,4-dithiouracil anions. Electron affinities of 0.61, 0.26, and 0.87 eV have been determined for 4-thiouracil, 2-thiouracil, and 2,4-dithiouracil, respectively. Electron propagator calculations on the canonical anions yield vertical electron detachment energies that are in close agreement with experimental peaks at 1.05, 3.21, and 3.32 eV for 4-thiouracil and at 1.4 eV for 2,4-dithiouracil.     

Synthesis and electronic absorption and fluorescence of 2-arylbenzothiazole derivatives

A series of new 2-arylbenzothiazoles have been prepared in high yields by Jacobson's cyclization condensation of 2-aminobenzenethiol with benzoyl chloride or benzaldehyde derivatives under three different routes. These compounds have been fully characterized by EA, IR, NMR and MS. The electronic absorption and fluorescence of these compounds have been systematically investigated for the first time. The relationships between their photophysical properties and structures have been discussed. The alteration of absorption and emission wavelengths can be elucidated by Hammett's substituent constants.     

Excess enthalpy and entropy of aqueous tetramethylguanidinium perchlorate and chloride and tetramethylammonium nitrate

Heats of dilution have been measured for aqueous solutions of tetramethylguanidinium perchlorate and chloride and for tetramethylammonium nitrate at 25°C. Excess enthalpies have been calculated and combined with excess free energy data which were previously published to yield excess entropy. These results furnish further evidence for the association of the tetramethylguanidinium salts in aqueous solutions.     

Relationship between the charge distribution and dipole moment functions of CO and the related molecules CS, SiO, and SiS

The dipole moment functions of the titled molecules are written as the sum of a charge and induced atomic dipole contribution and the distance dependence interpreted in terms of these components. These two contributions have opposite signs over a large range of internuclear distances, and when they have equal magnitudes, the dipole moment vanishes. This happens with CO near the equilibrium bond length and is responsible for its small dipole moment. The dipole moment of CS is 0.770(ea0), rather large for a diatomic in which the two atoms have essentially the same electronegativities; this is because for CS, the two components of the dipole moment have the same sign at equilibrium and reinforce one another.     

Preparations and applications of synthetic linked azamacrocycle ligands and complexes

Covalently linked azamacrocycles have been known for several decades, but only a modest number of these ligands and their complexes had been described prior to 2000. Since that time, a number of new synthetic methods for their preparation have been discovered, yielding a growing collection of these interesting ligands. Additionally, the number of uses to which these ligands and their metal complexes have been applied has expanded. In this review, the important synthetic methods yielding linked azamacrocycles will be outlined, and their applications will be discussed.     

Preparation and testing of stationary phases and modified capillaries for affinity chromatography and affinity capillary electrophoresis of pepsin

Three stationary phases have been prepared for affinity liquid chromatography isolation and separation of porcine and human pepsin. The phases contain 3,5-diiodo-L-tyrosine (DIT) bound to the supports HEMA BIO VS, HEMA BIO E and EPOXY TOYOPEARL. These phases have been tested on a model sample of porcine pepsin A and applied to human pepsin. Fractions have been collected and the chymase activity determined in selected analyses. For affinity CE, capillaries have been prepared by modifying the wall with 3-aminopropyltriethoxysilane, followed either by direct binding of DIT, or by binding L-tyrosine that was subsequently iodated. The dissociation constant K(d) has been determined for the pepsin-DIT complex from the changes in the electrophoretic mobilities.