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61.
Anna Michnik Aleksandra Kłos Zofia Drzazga 《Journal of Thermal Analysis and Calorimetry》2004,77(1):269-277
Protein unfolding events were studied by differential scanning calorimetry (DSC) for bovine serum albumin (BSA) aqueous solutions
exposed to radio-frequency radiation. No immediate effect of this radiation on thermal unfolding of BSA was observed. The
differences between irradiated and control samples have appeared during the storage of BSA solution. The irradiated samples
changed faster than non-irradiated. Our results indicated that the age-related changes were stronger for 3.5 and 5 MHz than
for 247 MHz frequency and dependent on energy power of radiation. Deconvolution of DSC traces allowed to study the effect
of radio-frequency radiation on each component transition.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
62.
Alan R. Katritzky Zofia Dega-Szafran Ragulan Ramanathan John R. Eyler 《Journal of mass spectrometry : JMS》1994,29(2):96-101
Ion—molecule reactions in toluene, toluene-d8, pyridine, 4-methyl-, 4-ethyl- and 4-terr-butylpyridine and quinoline and their mixtures were studied by ICR mass spectrometry at 10-7 Torr (1 Torr = 133.3 Pa). The reactions of benzyl (m/z 91), benzyl-d7 (m/z 98), methylbenzyl (m/z 105), and azabenzyl (m/z 92) ions with pyridines and quinoline were observed. The reactions of protonated pyridines with unprotonated molecules leading to homoconjugated ions (BHB)+ were detected. 相似文献
63.
Prof. Francesco Sannicolò Prof. Patrizia R. Mussini Prof. Tiziana Benincori Prof. Rocco Martinazzo Dr. Serena Arnaboldi Giulio Appoloni Dr. Monica Panigati Dr. Elsa Quartapelle Procopio Valentina Marino Dr. Roberto Cirilli Dr. Simone Casolo Prof. Wlodzimierz Kutner Dr. Krzysztof Noworyta Dr. Agnieszka Pietrzyk‐Le Zofia Iskierko Katarzyna Bartold 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10839-10847
The racemate of an inherently chiral “spider‐like” octathiophene monomer T83 , in which chirality is generated by torsion in its backbone, was synthesized. The racemate was resolved into configurationally stable antipodes by HPLC on a chiral stationary phase. Electrooxidation of the enantiomers resulted in materials displaying high enantiorecognition ability towards the antipodes of some chiral probes. Moreover, the T83 racemate demonstrated great aptitude to stimulate formation of 3D rigid architectures if used as a cross‐linking monomer for molecular imprinting. This feature was exploited to devise a molecularly imprinted polymer‐based chemosensor selective for a thymine–adenine oligonucleotide. 相似文献
64.
Zofia Rzączyńska Anna Danczowska-Burdon Justyna Sienkiewicz-Gromiuk 《Journal of Thermal Analysis and Calorimetry》2010,101(2):671-677
Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light
lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln2L3·nH2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na2L·H2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas
Na2L·H2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate
lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm−1 disappear on complex spectra and νas and νs of COO− groups appear thus indicating that complexation process took place. 相似文献
65.
Accurate oxidation potentials for organic compounds are critical for the evaluation of thermodynamic and kinetic properties of their radical cations. Except when using a specialized apparatus, electrochemical oxidation of molecules with reactive radical cations is usually an irreversible process, providing peak potentials, E(p), rather than thermodynamically meaningful oxidation potentials, E(ox). In a previous study on amines with radical cations that underwent rapid decarboxylation, we estimated E(ox) by correcting the E(p) from cyclic voltammetry with rate constants for decarboxylation obtained using laser flash photolysis. Here we use redox equilibration experiments to determine accurate relative oxidation potentials for the same amines. We also describe an extension of these experiments to show how relative oxidation potentials can be obtained in the absence of equilibrium, from a complete kinetic analysis of the reversible redox kinetics. The results provide support for the previous cyclic voltammetry/laser flash photolysis method for determining oxidation potentials. 相似文献
66.
The paper proposes a new method for amino acid determination which can be applied for amino acid profiling in solutions for parenteral nutrition. The MEKC method based on a mixed micellar system was developed for the separation of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatized amino acids. Background electrolyte was based on tris-borate buffer with high alkaline pH. Sodium dodecyl sulfate micelles were modified using 1,2-hexanediol as a co-surfactant. The effect of the modifier on amino acid migration was studied with respect to hydrophobicity of the analytes. The modifier appeared to be suitable to improve the separation of AQC-tagged amino acids without an adverse effect on buffer ionic strength or EOF velocity. The method was successfully validated and applied for amino acid profiling in medicinal preparations for parenteral nutrition. The results obtained were compared with a reference chromatographic method (amino acid analyser). 相似文献
67.
HONO/1,1-dichloroethylene/Ar matrices were subjected to UV radiation (lambda > 340 nm) from a medium pressure mercury lamp. The products of the photolysis were studied experimentally by means of FTIR spectroscopy and theoretically using the ab initio MP2 method. Two conformers of 2-nitroso-2,2-dichloroethanol molecule have been identified as the final products of the double addition reaction of the OH, NO radicals to 1,1-dichloroethylene. The additional reactive species observed in the matrix is tentatively identified as an 1,1-dichloro-2-hydroxyethyl radical, an intermediate formed by single addition of OH to 1,1-dichloroethylene. The three photoproducts have been identified and observed for the first time. The identities of the products have been justified by comparison with the experiments with deuterated DONO and by performing concentration and annealing studies as well as by reference to the spectral data of related molecules. The results of the quantum mechanical calculations confirmed both the assignment of the new molecules and mechanism of the reaction observed in our experiment. 相似文献
68.
Bogusaw Nowicki Jacek Hetper Zofia Wietrzyska-Lalak 《Reaction Kinetics and Catalysis Letters》2002,75(2):323-333
Performance of MnOx/Al2O3 catalytic systems was studied after they were roasted at different temperatures in the range of 650 – 1100°C. The maximum activity of the catalysts was reached when the catalyst roasting temperature was 1000°C. To explain the results, the X-ray diffraction analyses of THE catalysts were performed. 相似文献
69.
The osmotic and activity coefficients of aqueous sodium and potassium methyl sulfates have been determined at 25°C by the isopiestic method, in the molality range from ca.0.2 to 25 and 19 mol-kg–1, respectively. The results have been discussed in terms of the ion–ion and ion–water interactions on the basis of the Pitzer and Mayorga model and a method developed in our laboratory. 相似文献
70.
Anna Michnik Katarzyna Michalik Zofia Drzazga 《Journal of Thermal Analysis and Calorimetry》2005,80(2):399-406
Summary The effect of pH on the thermal denaturation of BSA containing fatty acids was studied by use of differential scanning calorimetry (DSC). Thermal scanning of BSA aqueous solutions gave various types of DSC curves depending on the protein concentration and on the pH. The broad bimodal endothermic transition was suggested to be connected with loose protein structure in contradistinction to single peak for compact molecule structure. The propensity toward precipitation at pH conditions ranging from 3.8 to 5 was observed. A scan-rate independent and partly reversible behavior of the thermal heating of BSA was found. Deconvolution of DSC traces in non-two-state model with assumption of two- or three-component transition allowed to study the effect of pH on different parts of BSA molecule. 相似文献