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991.
Yafarova Liliia V. Silyukov Oleg I. Myshkovskaya Tatiana D. Minich Iana A. Zvereva Irina A. 《Journal of Thermal Analysis and Calorimetry》2021,143(1):87-93
Journal of Thermal Analysis and Calorimetry - Protonation and hydration processes of layered perovskite-like oxide KCa2Nb3O10 during the reaction with nitric acid solutions with different... 相似文献
992.
Irina Stanciu Luminita Predoana Jeanina Pandele Cusu Silviu Preda Mihai Anastasescu Katarina Vojisavljević Barbara Malič Maria Zaharescu 《Journal of Thermal Analysis and Calorimetry》2017,129(2):639-654
This work aims to elucidate whether the hypothesis of zero oxygen at the mixture layer when flame takes place is assumable for every kind of material. For that purpose, we investigated the oxygen concentration there by cone calorimeter tests. A modified holder was developed in order to collect oxygen in this mixture layer. In addition, thermogravimetric tests were carried out so as to relate the possible effects of the presence of oxygen in the atmosphere where the pyrolysis process takes place, since the cone calorimeter does not allow to control the oxygen level of the atmosphere during the experiment. The reaction rates and per cent of residue in the cone calorimetric tests were measured and compared with the results from thermogravimetric tests. Six products were analysed which can be classified in three main groups: lignocellulosic, thermoplastic polymers and thermoset polymers. Cone calorimetric results showed that for some of the materials analysed (PET, Nylon and PUR foam) the oxygen level at mixture layer decreased until values close to zero. The comparison of reaction rates between cone calorimetric and thermogravimetric tests revealed the char layer created in cone calorimetric tests over the exposed face for brushed fir, Nylon and PET established an important heat barrier that modifies the thermal behaviour of these materials. 相似文献
993.
A Soft Grip: Magnesium Complexes with a Phosphine‐Modified Phosphonium Diylidic Lewis Base
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Dr. Jens Langer Irina Kosygin Dr. Ralph Puchta Jürgen Pahl Prof. Dr. Sjoerd Harder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17425-17435
Simple strategies to obtain magnesium complexes with the soft chelating diylidic ligand [Ph2PCHPPh2(fluorenylidene)]? (dppmflu?) were developed to evaluate the influence of the hard acid (cation) and soft base (anion) mismatch on the stability and reactivity of the formed derivatives. Deprotonation of the precursor Ph2PCH2PPh2(flu) (dppmfluH) by an alkylmagnesium derivative or magnesium amide provided access to [{Mg(dppmflu)(μ‐nBu)}2], [Mg(dppmflu){N(SiMe3)2}], and [{Mg(dppmflu)(μ‐Me)}2], which were used as starting materials for further investigations. The reaction of [{Mg(dppmflu)(μ‐nBu)}2] with PhSiH3 in the presence of THF allowed isolation of the magnesium hydride complex [{Mg(dppmflu)(μ‐H)(thf)}2] without a stabilizing nitrogen donor ligand. Prolonged heating enforced ligand redistribution and [{Mg(dppmflu)(μ‐H)(thf)}2] was converted to [Mg(dppmflu)2] and MgH2. The homoleptic derivative [Mg(dppmflu)2], in which the magnesium center is in a very soft ligand environment, can open a THF molecule by frustrated Lewis pair reactivity to give [{Mg(dppmflu)(μ‐OC4H8dppmflu)}2]. 相似文献
994.
995.
Synthetic chalcogen–phosphorus chemistry permanently makes new challenges to computational Nuclear Magnetic Resonance (NMR) spectroscopy, which has proven to be a powerful tool of structural analysis of chalcogen–phosphorus compounds. This paper reports on the calculations of one-bond 31P 77Se and 31P 125Te NMR spin–spin coupling constants (SSCCs) in the series of phosphine selenides and tellurides. The applicability of the combined computational approach to the one-bond 31P 77Se and 31P 125Te SSCCs, incorporating the composite nonrelativistic scheme, built of high-accuracy correlated SOPPA (CC2) and Coupled Cluster Single and Double (CCSD) methods and the Density Functional Theory (DFT) relativistic corrections (four-component level), was examined against the experiment and another scheme based on the four-component relativistic DFT method. A special J-oriented basis set (acv3z-J) for selenium and tellurium atoms, developed previously by the authors, was used throughout the NMR calculations in this work at the first time. The proposed computational methodologies (combined and ‘pure’) provided a reasonable accuracy for 31P 77Se and 31P 125Te SSCCs against experimental data, characterizing by the mean absolute percentage errors of about 4% and 1%, and 12% and 8% for selenium and tellurium species, respectively. The present study reports typical relativistic corrections to 77Se 31P and 125Te 31P SSCCs, calculated within the four-component DFT formalism for a broad series of tertiary phosphine selenides and tellurides with different substituents at phosphorus. 相似文献
996.
Olga V. Zhukova Evgenia V. Arkhipova Tatyana F. Kovaleva Sergey A. Ryabov Irina. P. Ivanova Anna A. Golovacheva Daria A. Zykova Sergey D. Zaitsev 《Molecules (Basel, Switzerland)》2021,26(16)
Cytostatic chemotherapeutics provide a classical means to treat cancer, but conventional treatments have not increased in efficacy in the past years, warranting a search for new approaches to therapy. The aim of the study was, therefore, to obtain methacrylic acid (MAA) (co)polymers and to study their immunopharmacological properties. 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid (CDSPA) and 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) were used as reversible chain transfer agents. Experiments were carried out in Wistar rats. The MTT assay was used to evaluate the cytotoxic effect of the polymeric systems on peritoneal macrophages. An experimental tumor model was obtained by grafting RMK-1 breast cancer cells. Serum cytokine levels of tumor-bearing rats were analyzed. The chain transfer agents employed in classical radical polymerization substantially reduced the molecular weight of the resulting polymers, but a narrow molecular weight distribution was achieved only with CDSPA and high CPDT concentrations. Toxicity was not observed when incubating peritoneal macrophages with polymeric systems. In tumor-bearing rats, the IL-10 concentration was 1.7 times higher and the IL-17 concentration was less than half that of intact rats. Polymeric systems decreased the IL-10 concentration and normalized the IL-17 concentration in tumor-bearing rats. The maximum effect was observed for a MAA homopolymer with a high molecular weight. The anion-active polymers proposed as carrier constituents are promising for further studies and designs of carrier constituents of drug derivatives. 相似文献
997.
Tabrizi Ali Akbar Al-Bugharbee Hussein Trendafilova Irina Garibaldi Luigi 《Meccanica》2017,52(4-5):1201-1217
Meccanica - Most conventional diagnostic methods for fault diagnosis in rolling bearings are able to work only for the case of stationary operating conditions (constant speed and load), whereas,... 相似文献
998.
For \(p\in [1,\infty ]\), we establish criteria for the one-sided invertibility of binomial discrete difference operators \({{\mathcal {A}}}=aI-bV\) on the space \(l^p=l^p(\mathbb {Z})\), where \(a,b\in l^\infty \), I is the identity operator and the isometric shift operator V is given on functions \(f\in l^p\) by \((Vf)(n)=f(n+1)\) for all \(n\in \mathbb {Z}\). Applying these criteria, we obtain criteria for the one-sided invertibility of binomial functional operators \(A=aI-bU_\alpha \) on the Lebesgue space \(L^p(\mathbb {R}_+)\) for every \(p\in [1,\infty ]\), where \(a,b\in L^\infty (\mathbb {R}_+)\), \(\alpha \) is an orientation-preserving bi-Lipschitz homeomorphism of \([0,+\infty ]\) onto itself with only two fixed points 0 and \(\infty \), and \(U_\alpha \) is the isometric weighted shift operator on \(L^p(\mathbb {R}_+)\) given by \(U_\alpha f= (\alpha ^\prime )^{1/p}(f\circ \alpha )\). Applications of binomial discrete operators to interpolation theory are given. 相似文献
999.
1000.
Non-stationary plane shock wave interaction with localized nanosecond-lasting surface discharges was investigated. Pulse discharge
plasma glow evolution was recorded with a CCD camera and gas flow evolution was recorded with laser shadowgraphy. CFD simulations
of pulse energy deposition near the horizontal wall surface in front of the shock wave were carried out. Non-stationary 2D
symmetrical flow dynamics were studied and analysis of the instantaneous surface discharge energy rate through CFD and shadow
images matching was carried out. 相似文献