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81.
82.
3,4-Diaroylfuroxans 1 react with various dipolarophiles 3 under microwave activation to afford the cycloadduct 4 instead of the expected isoxazole 5 in good yields in the absence of solvent. 相似文献
83.
N. Ouerfelli 《Physics and Chemistry of Liquids》2018,56(3):412-415
Expressions of Redlich–Kister (RK) excess function using polynomials on difference of molar composition are used. Calculated values of excess properties from experimental values are well presented in some curves as a function of mole fraction (x2) of the second pure component of the studied binary liquid mixture. Nevertheless, the authors presented values of adjustable parameters, not for the polynomial of the popular RK equation (i.e. vs. x2–x1), but for globally the excess property YE as an overall three degree polynomial on (x2) including implicitly the molar fraction product (x1·x2) in their nonlinear regression, which can then induces some readers to probable confusion. 相似文献
84.
Polystyrene-supported 2-azidoethyl phenyl selenide and 3-azidopropyl phenyl selenide reagents have been developed and applied to the traceless solid-phase organic synthesis of 1-vinyl- and 1-allyl-1,2,3-triazoles by CuI-mediated azide–alkyne cycloadditions and subsequent cleavage from the polymer support through oxidation–elimination reaction with 30% hydrogen peroxide. The advantages of this method include straightforward operation, good yield and purity of the products, and good stability and lack of odor for the reagents. 相似文献
85.
An investigation into the bulk properties, elastic properties and Debye temperature under pressure, and deformation mode under tension of Al8Cu4Y and Al8Cr4Y compounds was investigated by using first principles calculations based on density functional theory. The calculated lattice constants for the ternary compounds (Al8Cu4Y and Al8Cr4Y) are in good agreement with the experimental data. It can be seen from interatomic distances that the bonding between Al1 atom and Cr, Y, and Al2 atoms in Al8Cr4Y are stronger than Al8Cu4Y. The results of cohesive energy show that Al8Cr4Y should be easier to be formed and much stronger chemical bonds than Al8Cu4Y. The bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν can be obtained by using the Voigt–Reuss–Hill averaging scheme. From the results of elastic properties, Al8Cr4Y has the stronger mechanical behavior than Al8Cu4Y. Our calculations also show that pressure has a greater effect on mechanical behavior for both compounds. The ideal tensile strength are obtained by stress-strain relationships under [001](001) uniaxial tensile deformation, which are 15.4 and 23.4 GPa for Al8Cu4Y and Al8Cr4Y, respectively. The total and partial density of states and electron charge density under uniaxial tensile deformations for Al8Cu4Y and Al8Cr4Y compounds are also calculated and discussed in this work. 相似文献
86.
《Particuology》2016
The nanosize grain growth characteristics of spherical single-crystal titanium oxide (TiO2) during the rapid gaseous detonation reaction are discussed. Based on the experimental conditions and the Chapman–Jouguet theory, the Kruis model was introduced to simulate the growth characteristics of spherical TiO2 nanoparticles obtained under high pressure, high temperature and by rapid reaction. The results show that the numerical analysis can satisfactorily predict the growth characteristics of spherical TiO2 nanoparticles with diameters of 15–300 nm at different affecting factors, such as concentration of particles, reaction temperature and time, which are in agreement with the obtained experimental results. We found that the increase of the gas-phase reaction temperature, time, and particle concentration affects the growth tendency of spherical nanocrystal TiO2, which provides effective theoretical support for the controllable synthesis of multi-scale nanoparticles. 相似文献
87.
The dynamic string motion, which displacement is unilaterally constrained by the rigid termination condition of an arbitrary geometry has been simulated and analyzed. The treble strings of a grand piano usually terminate at a capo bar, which is situated above the strings. The apex of a V-shaped section of the capo bar defines the end of the speaking length of the strings. A numerical calculation based on the traveling wave solution is proposed for modeling the nonlinearity inducing interactions between the vibrating string and the contact condition at the point of string termination. It was shown that the lossless string vibrates in two distinct vibration regimes. In the beginning the string starts to interact in a nonlinear fashion with the rigid terminator, and the resulting string motion is aperiodic. Consequently, the spectrum of the string motion depends on the amplitude of string vibrations, and its spectral structure changes continuously with the passage of time. The duration of that vibration regime depends on the geometry of the terminator. After some time of aperiodic vibration, the string vibrations settle in a periodic regime where the resulting spectrum remains constant. 相似文献
88.
The solubility of gases in various polymers plays an important role for the design of new polymeric materials. Quantitative structure–property relationship (QSPR) models were designed to predict the solubility of gases such as CO2 and N2 in polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl acetate (PVA) and poly (butylene succinate) (PBS) at different temperatures and pressures by using quasi-SMILES codes. The dataset of 315 systems was split randomly into training, calibration and validation sets; random split 1 led to 214 training (r2 = 0.870 and RMSE = 0.019), 51 calibration (r2 = 0.858 and RMSE = 0.020) and 50 validation (r2 = 0.869 and RMSE = 0.017) sets. The suggested approach based on the quasi-SMILES, which are analogues of the traditional SMILES gives reasonable good predictions for solubility of CO2 and N2 in different polymers. The described methodology is universal for situations where the aim is to predict the response of an eclectic system upon a variety of physicochemical and/or biochemical conditions. 相似文献
89.
Vladimir Solozhenko 《高压研究》2013,33(2):317-318
Composite diamond anvils have been developed for high-pressure/high-temperature measurements of diamond anvil cells. The anvils are fabricated using single-crystal chemical vapor deposition (CVD) from previously used and/or slightly damaged anvils made of natural or synthetic diamond. These composite anvils can be fabricated to possess optical characteristics at least comparable to conventional diamond anvils, whereas the single-crystal CVD portion is more durable because of its enhanced toughness relative to natural diamond. The viability of such anvils is demonstrated in measurements on hydrogen at megabar pressures and high temperature. 相似文献
90.
Unexpected formation of β, meso-directly linked diporphyrin products has been described in the reactions of β-formyl porphyrins with pyrrole under Adler–Longo reaction conditions. Preliminary mechanistic studies indicates that β-dipyrromethane substituted porphyrin structure is the crucial intermediate for the formation of diporphyrin product. 相似文献