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991.
Periodica Mathematica Hungarica - The purpose of this paper is to give, through the second degree character, new characterizations of a part of the family of quasi-symmetric forms. In fact, thanks... 相似文献
992.
Hammami Asma Assaker Ibtissem Ben Chtourou Radhouane 《Journal of Solid State Electrochemistry》2022,26(1):211-218
Journal of Solid State Electrochemistry - In this work, we investigate the properties of manganese dioxide (MnO2) and graphene oxide (GO) to develop a new photoelectrochemical (PEC) sensor-based... 相似文献
993.
The aim of this work is to elaborate the LiNaWO4 compound, using the solid state method, then to characterize it using an XR study which confirms that it crystallizes in the orthorhombic system with P222 as space group and with the lattice parameters a = 12.82 Å, b = 17.49 Å, c = 7.25 Å and α = β = γ = 90°. The differential scanning calorimetry (DSC) shows two endothermic peaks at T1 = 388 K and T2 = 500 K. The first peak is detected by the dielectric study, attributed to a phase transition from a ferroelectric phase to a paraelectric one, while the second peak indicates the presence of a phase transition, confirmed later by the result of the electrical study. All modes pertaining to vibrations of WO42? tetrahedral appear in the Raman spectrum. Moreover, its impedance response is modeled by a single cell formed by a parallel combination of R//C//CPE, i.e. the response of our compound is that of the grain. The variation of the σg and σdc, as a function of temperature, confirms the phase transition observed in the calorimetric study at T2. The conduction mechanism in the two phases indicates that the first phase (I) is described by the CBH model and the second phase by the OLPT model. 相似文献
994.
Sami Ullah Humbul Suleman Muhammad Suleman Tahir Muhammad Sagir Shabbir Muhammad Abdullah G. Al-Sehemi Masood-ur-Rauf Zafar Firas A. Abdul Kareem Abdulhalim Shah Maulud Mohamad Azmi Bustam 《国际化学动力学杂志》2019,51(4):291-298
In this study, a new pressure drop method has been used to investigate the kinetics of carbon dioxide reaction with aqueous blend of 2-amino-2-ethyl-1,3-propanediol (AEPD) with piperazine (PZ). The blending of a small amount of PZ with AEPD has a significant effect on the observed rate constant, kobs. It was observed that kobs values of the blend increased more than twice than the summation of kobs values of individual alkanolamines. The reaction kinetics in this study were modeled by assuming a termolecular mechanism. The addition of 0.1 mol/L of PZ to 1 mol/L AEPD exhibited an observed rate constant, kobs of 8824.1 s−1, which is comparable to other alkanolamine mixtures. Hence, PZ/AEPD mixtures can be potentially used for rapid carbon dioxide capture. 相似文献
995.
The autoignition and pyrolysis of two C5 ethers, methyl tert butyl ether (MTBE) and 2-methyltetrahydrofuran (2-MTHF), are investigated using the shock tube reactor. The experiments are carried out at pressures of 3.5 and 12 atm at temperatures above 1000 K with argon as a diluent gas. By means of direct laser absorption, carbon monoxide time histories and associated chemical kinetic timescales are also determined. It is observed that the competition between ignition and pyrolysis times depends on the temperature and equivalence ratio of the ignition mixture, such that there is a temperature above which pyrolysis predominates oxidative kinetics. This crossover temperature shifts toward higher temperatures for reactive systems with a fixed fuel concentration but higher oxygen content. The resulting experimental observations are also compared with predictions of existing chemical kinetic models from the literature. The results point to differences in chemical reactivity, such that in pyrolysis conditions, the reactivity of the cyclic ether, 2-MTHF, is generally higher than that of the aliphatic ether, MTBE. While agreement between experimental observations and model predictions is observed under certain conditions, significant variance between observations and predictions is observed under other conditions. With respect to prediction of the pyrolysis time used to capture the global kinetics of pyrolysis, it is observed that the relation of this time to the time needed to attain 90% of the equilibrium CO concentration varies greatly with the result that the models used in this work generally predict a faster initial formation of CO but a much slower approach to the equilibrium concentration. This is thought to arise from the slow transformation of intermediate CH2O and CH2CO to CO. The chemical kinetic models considered in this work are therefore not capable of predicting the CO time histories during pyrolysis. 相似文献
996.
Dr. Jaime Mateos-Gil Anirban Mondal Dr. Marta Castiñeira Reis Prof. Dr. Ben L. Feringa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7897-7903
A palladium-catalyzed cross-coupling between in situ generated allenyl/propargyl-lithium species and aryl bromides to yield highly functionalized allenes is reported. The direct and selective formation of allenic products preventing the corresponding isomeric propargylic product is accomplished by the choice of SPhos or XPhos based Pd catalysts. The methodology avoids the prior transmetalation to other transition metals or reverse approaches that required prefunctionalization of substrates with leaving groups, resulting in a fast and efficient approach for the synthesis of tri- and tetrasubstituted allenes. Experimental and theoretical studies on the mechanism show catalyst control of selectivity in this allene formation. 相似文献
997.
We obtain upper Gaussian estimates of transition probabilities of inhomogeneous random walks on the positive quadrant. Among the most important steps in our proof are comparison arguments based on discrete variants of the Harnack principle and large deviations estimates. 相似文献
998.
999.
Quantum networks are distributed many-body quantum systems with tailored topology and controlled information exchange. We present two schemes to generate remote entanglement, in atomic external degrees of freedom and between cavities. In the first scheme, we entangle two atoms with their cavities in momentum space through Bragg diffraction. Thereafter, in order to trace out the cavities, we let resonantly interact an auxiliary atom with each cavity. In the last, we perform quantum measurement on two auxiliary atoms and get remote entangled state in atomic external degrees of freedom. In the second scheme, we have a three cavities system. The other two cavities, A and B, are entangled with indistinguishable modes of cavity, C. Performing quantum measurement on third cavity, C, we disentangle it from the system and the cavities, A and B, become entangled. 相似文献