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The reaction kinetics of nitric oxide (NO) with 2-hydroxyethyl radical (CH2CH2OH) radical was investigated over a wide temperature range of 200–1300 K and a pressure range of 1.0 × 10−4 –1.0 × 102 bar. Eight reactions channels were explored at G4 and CCSD(T)/cc-pVTZ // B3LYP/6–311++G(d, p) levels of theory, which consist of the same first step involving the formation of a adduct IM1 (ONCH2CH2OH) barrierlessly in the entrance channel. The channel producing P1 (CH2O and CH2NOH) were confirmed to be the most favourable over the calculated temperature range. RRKM – CVT method with Eckart tunnelling correction was employed to calculate the temperature-, pressure-dependent rate coefficients and yield of the most favourable reaction channels. The computed total rate coefficients agreed well with the available literature results. The individual and total rate coefficients showed negative temperature dependences. The reaction forming IM1 was dominated at low temperature and high-pressure conditions with a yield above 0.9 at the temperature less than 350 K and the pressure greater than 3 bar; while the channel producing P1 was dominated at high temperature and low pressure with a yield above 0.9 at the temperature higher than 1100 K and the pressure lower than 10−2 bar. [ABSTRACT FROM AUTHOR]

The reactions of XO 2 ∙ (X = CH3, H) with C2H5OH were investigated over the temperature range of 300–1500 K. The geometries of the stationary points were optimised at the MP2/aug-cc-pVTZ level and the energetics were refined at the CCSD(T)/aug-cc-pVTZ and the QCISD(T)/cc-pVTZ levels of theory. Six possible hydrogen abstraction channels were explored and it showed that the channels producing XO2H and CH3CHOH were favourable. The stable prereactive complexes were identified and their role was considered in the rate coefficient calculations. The rate coefficients have positive temperature dependence and the tunneling effect is more important at low temperature than at high temperature. [ABSTRACT FROM AUTHOR]

The mechanism for the C2H3+ CH3CH2OH reaction has been investigated by the CCSD(T)/cc-pVTZ method based on the geometries of stationary points optimised at the B3LYP/6-311++G(d, p) level of theory. Five reaction channels have been identified for the production of C2H4+ CH2CH2OH, C2H4+ CH3CH2O, C2H4+ CH3CHOH, C2H3OH + CH3CH2,and C2H3OCH2CH3+ H (denoted as channels (1)–(5), respectively). The potential barrier heights of the corresponding transition states TSR/P1, TSR/P2, TSR/P3, TSR/P4 and TSR/P5 were predicted to be 12.40, 8.50, 8.11, 38.38 and 42.21 kcal/mol at the CCSD(T)//B3LYP level of theory, respectively. The rate constants and branching ratios for the three lower energy H-abstraction channels were calculated using conventional transition state theory with Eckart tunnelling correction at the temperature range 300–2500 K. The predicted rate constants have been compared with the available literature data. Both the forward and reverse rate constants have positive temperature dependence, and the tunnelling effect is only important at low temperatures. The branching ratio calculation shows that channel (2) is predominant and channel (3) is less competitive, while channel (1) is almost neglectable at low temperatures. However, all three channels are important in high-temperature region. [ABSTRACT FROM PUBLISHER]

Abstract: Zirconium doped Cu/ZSM-5 catalysts were prepared and characterized in this investigation. Catalytic activity during soot combustion was determined in both O2/He and NO/O2/He atmospheres by temperature-programmed oxidation. The use of zirconium reduces the temperature of maximum soot oxidation rate by 229°C in O2/He atmosphere and 270°C in NO/O2/He atmosphere. The promoting effect of zirconium is discussed in terms of surface dispersion, enrichment of active components, and creation of oxygen vacancies where molecular oxygen or NO x is adsorbed forming basic surface oxygen species active for soot oxidation. The NO2 formed at the copper–zirconium interface sites leads to the ignition temperature being significantly decreased to 93°C, which is inside the exhaust temperature range of diesel engines. To understand the combustion reaction kinetics, the activation energy and reaction order of soot combustion were evaluated. According to the Redhead method, the activation energy for non-catalyzed reaction is 164kJ/mol under the O2/He atmosphere. For the Cu/ZSM-5 and Cu–Zr/ZSM-5, the activation energies under the O2/He atmosphere (134–151kJ/mol) are slightly higher than those under the NO/O2/He atmosphere (128–135kJ/mol). The Freeman–Carroll method is suitable to describe the soot combustion in the NO/O2/He atmosphere, with the activation energies for the catalysts in the range of 97–112kJ/mol and the average value of reaction order equal to 1.36. [Copyright &y& Elsevier]

Spectrometers based on acousto-optic tunable filters (AOTFs) have several advantages, such as stable temperature adaptability, no moving parts, and wavelength selection through electrical modulation, compared with the traditional grating and Fourier transform spectrometers. Therefore, AOTF spectrometers can realize stable in situ measurement on the lunar surface under wide temperature ranges and low light environments. AOTF imaging spectrometers were first employed for in situ measurement of the lunar surface in the Chinese Chang'e project. The visible and near-infrared imaging spectrometer and the lunar mineralogical spectrometer have been successfully deployed on board the Chang'e-3/4 and Chang'e-5 missions. In this review, we investigate the performance indicators, structural design, selected AOTF performance parameters, data acquisition of the three lunar in situ spectral instruments used in the Chang'e missions. In addition, we also show the scientific achievement of lunar technology based on in situ spectral data. [ABSTRACT FROM AUTHOR]

The size of dislocation rosettes introduced by indentation in the temperature range from 300 to 773 K are studied. The dislocation velocity and its temperature dependence are estimated. It is shown that the activation energy of dislocation movement at temperatures lower than 773 K does not exceed 1 eV. [ABSTRACT FROM AUTHOR]

• High-temperature and dynamic compressive responses of Al foams are studied. • Initial failure surface of Al foams is identified under high temperature conditions. • A theoretical constitutive model is proposed involving strain-rate effects. • The strain-rate dependent macro-mechanics models are numerically evaluated. Metallic foams exhibit great application prospects in some extreme working conditions such as high temperatures and/or high-velocity impact environments, but predominantly, their mechanical behavior has remained to be fully understood to date. In this study the uniaxial and biaxial tests are conducted on closed-cell aluminum foams at elevated temperatures. It is indicated that both drop stress and initial failure strength exhibit approximately linear relationship with the applied temperature, while the densification strain keeps almost at a constant value. The higher foam density or lower applied temperature, the larger the initial failure surface characterized in the von Mises - mean stress plane. However, the normalized failure surfaces nearly do not depend on foam density or temperature, and can be well fitted in terms of elliptical or parabolic function. Dynamic compressive tests under constant strain-rates reveal that the compressive strength is correlated to strain-rate positively, but the densification strain negatively. A novel rate-dependent constitutive model is proposed to describe the compressive constitutive behavior of Al foams. Finally, the crushable foam model with the tabular input of yield ratio approach can produce satisfactory numerical predictions compared to dynamic experimental results. This study provides new insights into the intrinsic mechanical properties of metallic foams under some extreme conditions. [Display omitted] [ABSTRACT FROM AUTHOR]