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471.
Ksenia V. Zherikova Natalia B. Morozova Ludmila N. Zelenina S. V. Sysoev Tamara P. Chusova I. K. Igumenov 《Journal of Thermal Analysis and Calorimetry》2008,92(3):729-734
Five volatile hafnium(IV) and zirconium(IV) β-diketonates: hafnium(IV) acetylacetonate, hafnium(IV) trifluoroacetylacetonate,
hafnium(IV) pivaloyltrifluoroacetonate, hafnium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate and zirconium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate
were obtained, purified and identified. Thermal behavior of solid compounds was investigated by thermogravimetry (TG) and
differential scanning calorimetry (DSC) in helium atmosphere and in vacuum. DSC method was also used for definition of thermodynamic
characteristics of melting processes. Using the static method with quartz membrane zero-manometer and the flow method the
temperature dependencies of saturated vapor pressure for hafnium(IV) complexes was obtained. The standard thermodynamic characteristics
ΔH
T0 and ΔS
T0 of sublimation and evaporation processes were calculated from the temperature dependences of saturated vapor pressure. 相似文献
472.
Svetlana F. Malysheva Nina K. Gusarova Natal'ya A. Belogorlova Tamara V. Kashik Leonid B. Krivdin Sergei V. Fedorov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1838-1844
A facile, one-pot vinylation of secondary phosphine chalcogenides with alkyl(or aryl) vinyl sulfoxides has been elaborated. The vinylation comprises the nucleophilic addition of secondary phosphine chalcogenides to the vinyl sulfoxides (~50 mol% KOH, dioxane, 25–40°C, 1 h) followed by the elimination of sulfenic acids from the adducts (additional equivalent of KOH, 60–70°C, 1.5–2.0 h), the yields of target tertiary vinyl phosphine chalcogenides reaching 92%. 相似文献
473.
The change of cellular glycosylation is one of the key events in malignant transformation and neoplastic progression, and tumor‐related glycosylation alterations are promising targets in both tumor diagnosis and therapy. Both malignant transformation and neoplastic progression are the consequence of gene expression alterations and alterations in protein expression. Micro environmental factors such as extracellular matrix (ECM) also play an important role in their growth and metastasis. Tumor‐associated glycans are important biomarker candidates for cancer diagnosis and prognosis, and analytical methods for their detection were developed recently. Glycoproteomics that use mass spectrometry for identification of cancer antigens and structural analysis of glycans play a key role in the investigation of changes of glycosylation during malignant transformation and tumor development and metastasis. Deep understanding of glycan remodeling in cancer and the role of glycosyltransferases that are involved in this process will require a detailed profiling of glycosylation patterns of tumor cells, and corresponding analytical methods for their detection were developed. 相似文献
474.
Background
The capsaicin (vanilloid) receptor, VR1, is an agonist-activated ion channel expressed by sensory neurons that serves as a detector of chemical and thermal noxious stimuli. 相似文献475.
Dr. Bojana B. Laban Dr. Tamara Lazarević-Pašti Dr. Djordje Veljović Dr. Mirjana Marković Urszula Klekotka 《欧洲无机化学杂志》2023,26(12):e202200754
The silver and gold L-methionine capped nanoparticles (Ag and Au @LM NPs) were analyzed as prospective acetylcholinesterase (AChE) inhibitors to test their potential in the treatment of cognitive impairment in depression and Alzheimer's disease. The stability of NPs, and their ability to inhibit AChE were studied by UV-Vis and FTIR spectrophotometry. At the same time, TEM and SEM measurements, DLS, and zeta potential measurements were employed in the structural characterization of NPs. Nearly spherical, negatively charged Ag and Au @LM NPs, with 17 nm and 31 nm in diameter, respectively, showed moderate inhibitory potential toward AChE in the given frame of investigated concentrations. For both NPs IC50 is not reached. Furthermore, the adsorption of enzyme molecules on the surface of Ag and Au @LM NPs was demonstrated. Hence, our assumption is that inhibition of AChE is caused by blockage of the enzyme‘s active site due to the steric hindrance of NPs. 相似文献
476.
Vladimir V. Pelipenko Dmitry I. Kochubey Alexander A. Khassin and Tamara M. Yurieva 《Reaction Kinetics and Catalysis Letters》2005,86(2):307-314
Summary Cu K EXAFS studies of the structure of Cu-Zn oxide catalyst were performed for the as prepared samples, those after its activation
by hydrogen and after its subsequent re-oxidation. It was found that during the primary formation of the CuZnO solid solution,
the copper ions are dissolved in the extended stacking faults of the ZnO lattice as ultra-small oxide clusters. Activation
by hydrogen at 473 K leads to the reduction of most copper cations to Cu0with the formation of nanoparticles with the characteristic size of ca. 1.6 nm. The copper metal particles were re-oxidized to Cu2+at 523 K in<span lang=EN-US style='mso-ansi-language:EN-US'>ahelium flow containing 0.05 vol. % oxygen. The re-oxidized cations
do not form a CuO phase. Instead, they return to the extended stacking faults of ZnO. However, this time they form stripe-like
clusters of square-planar coordinated copper cations. 相似文献
477.
Kirillova TN Gerasimova MA Nemtseva EV Kudryasheva NS 《Analytical and bioanalytical chemistry》2011,400(2):343-351
The paper investigates an application of luminescent bioassays to monitor the toxicity of organic halides. Effects of xanthene
dyes (fluorescein, eosin Y, and erythrosin B), used as model compounds, on bioluminescent reactions of firefly Luciola mingrelica, marine bacteria Photobacterium leiognathi, and hydroid polyp Obelia longissima were studied. Dependence of bioluminescence quenching constants on the atomic weight of halogen substituents in dye molecules
was demonstrated. Bacterial bioluminescence was shown to be most sensitive to heavy halogen atoms involved in molecular structure;
hence, it is suitable for construction of sensors to monitor toxicity of halogenated compounds. Mechanisms of bioluminescence
quenching—energy transfer processes, collisional interactions, and enzyme–dye binding—were considered. Changes of bioluminescence
(BL) spectra in the presence of the dyes were analyzed. Interactions of the dyes with enzymes were studied using fluorescence
characteristics of the dyes in steady-state and time-resolved experiments. The dependences of fluorescence anisotropy of enzyme-bound
dyes, the average fluorescence lifetime, and the number of exponential components in fluorescence decay on the atomic weight
of halogen substituents were demonstrated. The results are discussed in terms of “dark effect of heavy halogen atom” in the
process of enzyme–dye binding; hydrophobic interactions were assumed to be responsible for the effect. 相似文献
478.
The stereoselective synthesis of (1R,2R)- and (1S,2S)-trans-2-(diphenylmethylideneamino)cyclopropanecarboxylic acid has been accomplished in six steps starting from (2S)- and (2R)-β-benzyl N-(tert-butoxycarbonyl)aspartate, respectively. The key-step in the reaction sequence is a stereoselective base-induced ring closure with a good trans diastereoselectivity. These novel trans-β-ACC derivatives could be incorporated in dipeptides employing a standard peptide coupling technique. 相似文献
479.
480.
Daria V. VorobyevaArtur K. Mailyan Alexander S. PeregudovNatalia M. Karimova Tamara P. VasilyevaIvan S. Bushmarinov Christian BruneauPierre H. Dixneuf Sergey N. Osipov 《Tetrahedron》2011,67(19):3524-3532
A new efficient access to functionalized CF3-substituted and nitrogen or sulfur-containing heterocycles has been developed directly from diazocompounds CF3C(N2)Z (Z=CO2Me, P(O)(OEt)2). The method is based on the direct selective synthesis of doubly unsaturated substrates followed by metal-mediated carbocylization. The first step has been performed by Cu(II)-catalyzed [2,3]-sigmatropic rearrangement of propargyl- or/and allyl-containing sulfur and nitrogen ylides leading to fluorinated enynes, diolefins, and especially allenynes derivatives. The second step involves their carbocyclization via ring closing metathesis and Pauson-Khand reaction. 相似文献