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991.
S. M. Frolov V. I. Zvegintsev V. S. Ivanov V. S. Aksenov I. O. Shamshin D. A. Vnuchkov D. G. Nalivaichenko A. A. Berlin V. M. Fomin 《Doklady Physical Chemistry》2017,474(1):75-79
First experimental investigations were carried out into the detonation combustion of hydrogen in a demonstrator of an original-design air-breathing ramjet while blowing with an air flow at Mach 4 to 8 in an impulse wind tunnel, and for the first time under these conditions, continuous spin and longitudinal pulsed modes of detonation combustion of hydrogen in an annular combustor were detected. 相似文献
992.
S. D. Varfolomeev E. D. Kots M. G. Khrenova S. V. Lushchekina A. V. Nemukhin 《Doklady Physical Chemistry》2017,474(2):89-92
The results of modeling of the complete catalytic cycle of aspartoacylase-catalyzed N-acetylaspartate hydrolysis by the combined quantum mechanics/molecular mechanics method and with the use of umbrella sampling replica-exchange molecular dynamics simulations are reported. It has been shown that the decrease in the high-energy barriers of rate-limiting stages is achieved through the preceding equilibrium stages, such as proton transfer and conformational changes. General features of the catalytic behavior of enzymes have been formulated. 相似文献
993.
Isomeric effects on the self‐assembly of a plausible prebiotic nucleoside analogue: A theoretical study 下载免费PDF全文
Emmanuel Vallejo Miguel Fuentes‐Cabrera Bobby G. Sumpter Eduardo Rangel Cortes 《International journal of quantum chemistry》2017,117(3):213-221
The self‐assembly properties of N(9)‐(2,3‐dihydroxypropyl adenine) (DHPA), a plausible prebiotic nucleoside analogue of adenosine, were investigated using density functional theory. Two different isomers were considered, and it is found that while both isomers can form a variety of structures, including chains, one of them is also able to form cages and helixes. When these results were put in the context of substrate supported molecular self‐assembly, it is concluded that gas‐phase self‐assembly studies that consider isomer identity and composition not only can aid interpreting the experimental results, but also reveal structures that might be overlooked otherwise. In particular, this study suggest that a double‐helical structure made of DHPA molecules which could have implications in prebiotic chemistry and nanotechnology, is stable even at room temperature. For example electrical properties (energy gap of 4.52eV) and a giant permanent electrical dipole moment (49.22 Debye) were found in our larger double‐helical structure (3.7 nm) formed by 14 DHPA molecules. The former properties could be convenient for construction of organic dielectric‐based devices. 相似文献
994.
Thermodynamic characteristics of stepwise dissociation of glycyl-glycyl-glycine in aqueous solutions
A. I. Lytkin V. V. Chernikov O. N. Krutova G. G. Gorboletova I. A. Skvortsov A. S. Korchagina 《Russian Journal of Inorganic Chemistry》2017,62(2):240-243
The heats of interaction between glycyl-glycyl-glycine and solutions of nitric acid and potassium hydroxide are determined by calorimetry at 298.15 K and ionic strengths of 0.25, 0.50, and 0.75 in the presence of KNO3. The standard thermodynamic characteristics (Δr H°, Δr G°, and Δr S°) of acid–base interaction in aqueous solutions of the peptide are calculated. The effect of background electrolyte concentration on the enthalpy of dissociation of glycyl-glycyl-glycine is discussed. 相似文献
995.
T. G. Aminov G. G. Shabunina E. V. Busheva V. M. Novotortsev 《Russian Journal of Inorganic Chemistry》2017,62(3):361-371
Temperature-dependent magnetization was measured for CuCr2–x Sb x Sе4 solid solutions in the range 300–5 K in a weak field (50 Oe) and a strong field (10 kOe) and in an ac magnetic field having a frequency of 100–10000 Hz and an amplitude of Н = 1 Oe. The type and character of magnetic transitions under investigation in the system were determined, and its magnetic phase diagram was constructed. 相似文献
996.
In‐Planta Expression: Searching for the Genuine Chromophores of Cryptochrome‐3 from Arabidopsis thaliana 下载免费PDF全文
Wolfgang Gärtner 《Photochemistry and photobiology》2017,93(1):382-384
Göbel et al. present in this issue an exemplary study of identification of chromophores from Arabidopsis thaliana cryptochrome‐3. Usually taken for granted, proteins and cofactors, respective chromophores, from heterologous expression are considered identical to material isolated from their genuine host. Cryptochromes carry two chromophores, an antenna cofactor and a functional flavin chromophore, both noncovalently embedded into the protein. In particular the antenna chromophore is loosely bound and often lost during protein purification. The authors identify from plant‐extracted Cry3 unambiguously N5,N10‐methenyltetrahydrofolate as antenna chromophore and flavin adenine dinucleotide as the functional chromophore. 相似文献
997.
Flavin Adenine Dinucleotide and N5,N10‐Methenyltetrahydrofolate are the in planta Cofactors of Arabidopsis thaliana Cryptochrome 3 下载免费PDF全文
Tanja Göbel Stefan Reisbacher Alfred Batschauer Richard Pokorny 《Photochemistry and photobiology》2017,93(1):355-362
Members of the cryptochrome/photolyase family (CPF) of proteins utilize noncovalently bound light‐absorbing cofactors for their biological function. Usually, the identity of these cofactors is determined after expression in heterologous systems leaving the question unanswered whether these cofactors are identical to the indigenous ones. Here, cryptochrome 3 from Arabidopsis thaliana was expressed as a fusion with the green fluorescent protein in Arabidopsis plants. Besides the confirmation of the earlier report of its localization in chloroplasts, our data indicate that fractions of the fusion protein are present in the stroma and associated with thylakoids, respectively. Furthermore, it is shown that the fusion protein expressed in planta contains the same cofactors as the His6‐tagged protein expressed in Escherichia coli, that is, flavin adenine dinucleotide and N5,N10‐methenyltetrahydrofolate. This demonstrates that the heterologously expressed cryptochrome 3, characterized in a number of previous studies, is a valid surrogate of the corresponding protein expressed in plants. To our knowledge, this is also a first conclusive analysis of cofactors bound to an Arabidopsis protein belonging to the CPF and purified from plant tissue. 相似文献
998.
The possible application of microemulsions as extractants for the extraction of o-phthalate esters from soils with the subsequent breakdown of microemulsions, simultaneous preconcentration of dialkhylphthalates in the organic phase, and their following gas chromatographic analysis with mass-spectrometric detection is demonstrated. The preconcentration factor was 18. The method is characterized by low detection limits, good selectivity, and reproducibility. 相似文献
999.
V. G. Amelin M. A. Saun’kina A. M. Andoralov 《Moscow University Chemistry Bulletin》2017,72(6):315-321
The possibility of directly determining 36 pesticides (derivatives of urea, triazines, triazoles, imidazoles, carbamates, triazinones, benzamides, and pyridazinones and organophosphorus pesticides) by electrospray ionization with high-resolution quadrupole time-of-flight mass spectrometry in natural waters is demonstrated. A significant matrix effect is observed in the determination of pesticides in natural waters, and the use of the standard addition method is proposed for their determination in test samples, both undiluted and diluted with deionized water. The analytical range of the analytes was 0.5–50 ng/mL. The relative standard deviation of the results does not exceed 10%; the time required for the analysis is 10–15 min. 相似文献
1000.
Validation of Sun Exposure Reported Annually Against Interim Self‐report and Daily Sun Diaries 下载免费PDF全文
Laura King Fan Xiang Ashwin Swaminathan Keith Dear Simone L. Harrison Ingrid van der Mei Michael G. Kimlin Catherine D'Este Robyn M. Lucas 《Photochemistry and photobiology》2017,93(5):1294-1302
Data on personal sun exposure over a period exceeding the immediate past days or weeks are typically self‐reported in brief questionnaire items. The validity of such self‐reporting of longer term personal sun exposure, for example over a year, including detail on variation across seasons, has not previously been investigated. In a volunteer sample (n = 331) of Australian adults aged 18 years and over, we assessed the 12‐month reliability of sun exposure reported separately for each season, and its accuracy compared to a daily sun diary in the same season. Seasonal time outdoors displayed fair‐to‐good reliability between baseline and end of study (12 months), with responses showing higher agreement at lower levels of time outdoors. There was good agreement for ranking of individuals' time outdoors with the daily sun diary data, although the actual diary time outdoors was typically considerably lower than the self‐reported questionnaire data. Place of residence, education, being a smoker, day of the week (i.e. working day vs nonworking day) and working mainly outdoors were significant predictors of agreement. While participants overestimated their actual time outdoors, the self‐report questionnaire provided a valid ranking of long‐term sun exposure against others in the study that was reliable over time. 相似文献