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61.
Shashi B. Kalia Rajesh Kumar Monika Bharti J. Christopher 《Journal of Thermal Analysis and Calorimetry》2017,127(2):1291-1306
Some new carbamates, viz. M(MorphcbmH)2X2 (MorphcbmH = morpholinecarbamic acid, M = Cu, X = Cl, ClO4,NO3; M = Zn, X = Cl, ClO4, NO3, CH3COO and X2 = SO4), have been synthesized and investigated. Compounds were characterized by elemental analysis, molar conductance, FT infrared, fluorescence, NMR (1H and 13C) and solution electronic absorption spectral studies. Room temperature field-dependent magnetic susceptibility measurements, PXRD spectral and cyclic voltametric studies were also conducted. Chelating bidentate mode of coordination of ligand, MorphcbmH with four coordination around metal ion has been proposed. Ligand and its compounds have also been studied using non-isothermal thermogravimetric analysis and differential scanning calorimetric analytical techniques which inferred formation of metal oxide/MCO3 as final thermal decomposition products. Compounds were screened against the lipase enzyme for assaying their enzyme activity and were found to retard the lipase activity from 48.16 to 0.044 µmol mL?1 min?1. 相似文献
62.
Cellobiohydrolase (CBH) is an important enzyme for the conversion of lignocellulosic biomass to ethanol. This work separated the glycoforms of CBH possessing different numbers of neutral mannoses using capillary zone electrophoresis (CZE) in a 50 mM, pH 7.5 phosphate buffer. The method analysed CBH in an intact form using a polyacrylamide coated fused silica capillary without requiring additives or labelling of the enzyme. The migration time of the major peak was found to be 21.6±0.1 min (n=3) and the approach is suitable for testing of batch-to-batch consistency of CBH. Ease-of-use, automation and speed are the other benefits due to which the use of CZE for analysing glycoforms of CBH was concluded to be ideal. 相似文献
63.
New triorganotin(IV) derivatives of the general formula R3Sn(Umb) (where, R = Me, n-Bu and Ph; Umb = umbelliferone anion) have been synthesized using sodium salt method. Further, the adducts of the general formula R3Sn(Umb) · phen (where R = Me and Ph; phen = 1,10-phenanthroline) have also been synthesized by the interaction of the triorganotin(IV) derivatives of umbelliferone with 1,10-phenanthroline. The bonding and coordination behavior of these derivatives are discussed on the basis of IR, NMR (1H, 13C and 119Sn), and 119Sn Mössbauer spectroscopic studies. These investigations indicate that umbelliferone acts as a monoanionic bidentate ligand in R3Sn(Umb) coordinating through O(7) and O(1) in the solid-state. These polymeric R3Sn(Umb) derivatives (where R = Me and n-Bu) have been proposed to have a trans-trigonal bipyramidal geometry with the three R groups in equatorial positions, while the axial positions are occupied by a phenolic oxygen and the O(1) atom from the adjacent molecule. A pseudotetrahedral geometry has been suggested for Ph3Sn(Umb). A distorted octahedral geometry around tin has been proposed for R3Sn(Umb) · phen, in which umbelliferone anion acts as a monodentate ligand coordinating through phenolic oxygen O(7). The newly synthesized derivatives have been assayed for their anti-inflammatory, cardiovascular and anti-microbial activities. The average LD50 values >1000 mg kg−1 of these derivatives indicate their safety margin. Among all the compounds tested, Ph3Sn(Umb) · phen has been found to show potent anti-inflammatory activity with low mammalian toxicity and mild hypotensive activity. 相似文献
64.
Wise CA Paris M Morar B Wang W Kalaydjieva L Bittles AH 《Rapid communications in mass spectrometry : RCM》2003,17(11):1195-1202
Analysis of single nucleotide polymorphisms (SNPs) has become an increasingly important area of research, with numerous applications in medical genetics, population genetics, forensic science, and agricultural biotechnology. Large-scale SNP analyses require the development of methodologies that are economical, flexible, accurate and capable of automation. Primer extension in conjunction with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is currently emerging as a potential method for high-throughput SNP genotyping. We have evaluated a number of published primer extension methods and refined a simple and robust protocol to analyze human autosomal disease-causing mutations and population genetic markers on the Y-chromosome. Twelve different variant sites were examined, and homozygotes, heterozygotes and hemizygotes were accurately typed. A 100% concordance was observed between SNP genotypes obtained using the MALDI-TOFMS technique and alternative genotyping methods, such as restriction fragment length polymorphism (RFLP) assays and denaturing high-performance liquid chromatography (DHPLC). Since multiple polymorphisms can be detected in single reactions, the method provides a cost-effective approach for SNP analysis. The protocol is also extremely flexible (able to accommodate new markers) and can be adapted to a number of platforms without the use of commercial kits. 相似文献
65.
Santanu Roy Shobha Sharma Waruni V. Karunaratne Fei Wu Ruchi Gakhar Dmitry S. Maltsev Phillip Halstenberg Milinda Abeykoon Simerjeet K. Gill Yuanpeng Zhang Shannon M. Mahurin Sheng Dai Vyacheslav S. Bryantsev Claudio J. Margulis Alexander S. Ivanov 《Chemical science》2021,12(23):8026
Enhancing the solar energy storage and power delivery afforded by emerging molten salt-based technologies requires a fundamental understanding of the complex interplay between structure and dynamics of the ions in the high-temperature media. Here we report results from a comprehensive study integrating synchrotron X-ray scattering experiments, ab initio molecular dynamics simulations and rate theory concepts to investigate the behavior of dilute Cr3+ metal ions in a molten KCl–MgCl2 salt. Our analysis of experimental results assisted by a hybrid transition state-Marcus theory model reveals unexpected clustering of chromium species leading to the formation of persistent octahedral Cr–Cr dimers in the high-temperature low Cr3+ concentration melt. Furthermore, our integrated approach shows that dynamical processes in the molten salt system are primarily governed by the charge density of the constituent ions, with Cr3+ exhibiting the slowest short-time dynamics. These findings challenge several assumptions regarding specific ionic interactions and transport in molten salts, where aggregation of dilute species is not statistically expected, particularly at high temperature.Ion clustering of dilute chromium species was unexpectedly revealed in a high-temperature molten chloride salt, challenging several long-held assumptions regarding specific ionic interactions and transport in molten ionic media. 相似文献
66.
67.
Radhey Mohan Naik Ruchi Singh Abhas Asthana 《Journal of Dispersion Science and Technology》2013,34(2):216-225
The kinetics and mechanism of ligand substitution reaction of coordinated water in complex, [Ru(CN)5H2O]3? by two incoming naphthalene substituted ligands [Ln], that is, Ln = nitroso-R-salt (NRS) and α-nitroso-β-naphthol (αNβN) have been studied spectrophotometrically by following an increase in absorbance at λmax = 525 nm in aqueous medium in presence of anionic surfactant micelle, sodium dodecyl sulphate (SDS) at 25.0 ± 0.1°C as a function of pH, [nitro-R-salt], [α-nitroso-β-naphthol], [Ru(CN)5H2O3?], [SDS] and ionic strength(I) under pseudo-first-order conditions by taking excess [L]. The values of pseudo-first-order rate constants (kobs) were evaluated from the slope of ln(A∞ ? At) versus time plots for each variation. Both systems were found to follow a dissociative mechanism (D), through the formation of an intermediate, [Ru(CN)5]3?. The activation parameters, that is, enthalpy of activation (ΔH≠) and entropy of activation (ΔS≠) were computed from the slope and intercept of ln(kf/T) versus (1/T) plot, which support the proposed mechanistic scheme. 相似文献
68.
Fabric phase sorptive extraction (FPSE) has become a popular sorptive-based microextraction technique for the rapid analysis of a wide variety of analytes in complex matrices. The present study describes a simple and green analytical protocol based on in-matrix methyl chloroformate (MCF) derivatization of non-steroidal anti-inflammatory (NSAID) drugs in urine samples followed by FPSE and gas chromatography-mass spectrometry (GC-MS) analysis. Use of MCF as derivatizing reagent saves substantial amounts of time, reagent and energy, and can be directly performed in aqueous samples without any sample pre-treatment. The derivatized analytes were extracted using sol–gel Carbowax 20M coated FPSE membrane and eluted in 0.5 mL of MeOH for GC-MS analysis. A chemometric design of experiment-based approach was utilized comprising a Placket–Burman design (PBD) and central composite design (CCD) for screening and optimization of significant variables of derivatization and FPSE protocol, respectively. Under optimized conditions, the proposed FPSE-GC-MS method exhibited good linearity in the range of 0.1–10 µg mL−1 with coefficients of determination (R2) in the range of 0.998–0.999. The intra-day and inter-day precisions for the proposed method were lower than <7% and <10%, respectively. The developed method has been successfully applied to the determination of NSAIDs in urine samples of patients under their medication. Finally, the green character of the proposed method was evaluated using ComplexGAPI tool. The proposed method will pave the way for simper analysis of polar drugs by FPSE-GC-MS. 相似文献
69.
70.
A theoretical study is made on the mobile interstitial and mobile electron models of mechano-induced luminescence in coloured
alkali halide crystals. Equations derived indicate that the mechanoluminescence intensity should depend on several factors
like strain rate, applied stress, temperature, density of F-centres and volume of crystal. The equations also involve the
efficiency and decay time of mechanoluminescence. Results of mobile interstitial and mobile electron models are compared with
the experimental observations, which indicated that the latter is more suitable as compared to the former. From the temperature
dependence of ML, the energy gaps between the dislocation band and ground state of F-centre is calculated which are 0.08,
0.072 and 0.09 eV for KCl, KBr and NaCl crystals, respectively. The theory predicts that the decay of ML intensity is related
to the process of stress relaxation in crystals. 相似文献