Geometrical structures of poly(haloalkyl propiolate)s prepared with a [Rh(norbornadiene)Cl]2 catalyst

The polymerization of ω-haloalkyl propiolates initiated by [Rh(norbornadiene)Cl]₂ in methanol has been investigated in detail together with the geometrical forms of the resulting polymers. The polymer yield and molecular weight of poly(2-haloethyl propiolate)s (P(2XEPA)s) were markedly reduced in the order of X = Cl, Br, and I. ¹H NMR, electron spin resonance, and diffuse reflective UV-vis spectroscopic studies of P(2XEPA)s revealed that the content of cis form regarding the CC was markedly decreased from 60% for P(2ClEPA) to 15% for P(2IEPA). The decrease in the cis content also resulted in notable reduction of the crystallinity of the polymer from 30% for P(2ClEPA) to less than 10% for P(2IEPA). Compression of P(2XEPA)s at room temperature induced the so-called cis-to-trans isomerization accompanied with decomposition of the polymers.     

Coal hydrogasification: Entrained flow bed design-operation and experimental study of hydrogasification characteristics

Coal hydrogasification processes including wire-mesh grid reactor, batch reactor, curie-point pyrolyzer, fixed bed reactor and so on were utilized or developed in laboratory researches. Although the experimental results could help to understand the basic behavior of coal hydrogasification, it was difficult to directly utilize such data for devising a new hydrogasifier. This paper designed a continuous entrained flow bed facility and described the hydrogasification characteristics. This device (15–30 kg/d) mainly consisted of a high-H₂ pressure feed system, a high-temperature tube reactor. The capabilities were shown as follows: the temperature from 700 °C to 850 °C, H₂ pressure from 0.1 MPa to 3.0 MPa, isothermal zone 300–600 mm, feeding rate from 15 to 30 kg/d and water yield was easy to obtained by tar-water separation. The good mass balance on the carbon and weight basis was established by analyzing the product distribution in detail. The results showed the yields of CH₄ and light aromatic hydrocarbons increased through hydrogenation of tar and volatiles, hydrogasification of coal char. Although the small pilot plant had high heat loss through refractory with increasing H₂ pressure, the typical results obtained from the continuous stable operation of the entrained flow bed reactor confirmed the design of new large-scale hydrogasification process was technical feasibility.     

羟基萘醌的合成及对羊毛织物防紫外线整理

文中以1,6-二羟基萘为原料、硫酸铈为氧化剂、正己烷为溶剂,氧化合成2,5-二羟基-1,4-萘醌(AUNQ-1),优化了合成工艺条件,并将AUNQ-1应用于羊毛织物的染色,测试染色后织物的染色牢度及防紫外线性能。结果表明,AUNQ-1优化合成条件为:n1,6-二羟基萘∶n硫酸铈=1∶4,反应温度20℃,反应时间1.2 h,最佳工艺条件下产率为26.31%;AUNQ-1染色羊毛织物耐皂洗色牢度和耐摩擦色牢度达到3~4级,紫外线透过率小于5.00%,UPF值大于50,具有优异的防紫外线性能。     

A consistent chemical mechanism for oxidation of substituted aromatic species

Computational studies of combustion in engines are typically performed by modeling the real fuel as a surrogate mixture of various hydrocarbons. Aromatic species are crucial components in these surrogate mixtures. In this work, a consistent chemical mechanism to predict the high temperature combustion characteristics of toluene, styrene, ethylbenzene, 1,3-dimethylbenzene (m-xylene), and 1-methylnaphthalene is presented. The present work builds on a detailed chemical mechanism for high temperature oxidation of smaller hydrocarbons developed by Blanquart et al. [Combust. Flame 156 (2009) 588-607]. The base mechanism has been validated extensively in the previous work and is now extended to include reactions of various substituted aromatic compounds. The reactions representing oxidation of the aromatic species are taken from the literature or are derived from those of the lower aromatics or the corresponding alkane species. The chemical mechanism is validated against plug flow reactor data, ignition delay times, species profiles measured in shock tube experiments, and laminar burning velocities. The combustion characteristics predicted by the chemical model compare well with those available from experiments for the different aromatic species under consideration.     

生物柴油的发展与研究进展

综述了可替代柴油的生物柴油在国内外研究及生产的现状和发展趋势,指出了生物柴油的优势及生物柴油制备、应用中存在的问题,并展望了该产业的发展前景。     

Electrochromic properties of poly{3-[12-(p-methoxyphenoxy)dodecyl]thiophene}

Poly{3-[12-(p-methoxyphenoxy)dodecyl]thiophene} films with different thickness were potentiostatically deposited on optically transparent glass electrodes using different deposition charges. Their spectroelectrochemical properties were studied as a function of thickness, i.e., deposition charge. Films obtained with a deposition charge of ca. 65 mC cm⁻² presented more stability to a high number of redox cycles (>1000), chromatic contrast of 40% at 725 nm, coulombic efficiency of 80% and good optical memory in the reduced state (E=0.0 V). The surface morphology of these films was also characterized by atomic force microscopy. Films obtained with a deposition charge ≤65 mC cm⁻² are homogeneous, while above this value the film surface morphology presents roughness and irregularities. Correlation between deposition charge and film thickness was estimated using a rugosimeter and atomic force microscopy experiments.     

基于非标准替换法的控制系统仿真

该文通过研究控制系统中常用的双线性替换法,发现在应用该方法时微分算子s与位移算子z相互间的关系不变。考虑得到该替换法的推导过程,发现在其进行转化的时候,微分算子与位移算子关系可以是一种变化的形式。应用不同的对应关系对同一表达式进行替换可得到不同的结果,于是提出了一种连续时间控制系统数字仿真的非标准替换法。通过将该方法与标准双线性替换法进行对比仿真计算,仿真结果表明该替换法比双线性替换法具有更强的灵活性与仿真精度。     

Order–disorder transition in the Dy0.2Sr0.8CoO3-δ rare-earth cobalt oxide solid solutions: Structural and thermoelectric properties

By the example of the Dy_0.2Sr_0.8CoO_3-δ compound undergoing an order–disorder phase transition with increasing temperature, we demonstrate a significant dependence of the kinetic properties on the morphology of the internal spatially inhomogeneous structure, which forms in the sample depending on the rate of its transition from the high-temperature disordered cubic phase to the ground tetragonal ordered phase upon cooling. The results of transmission electron microscopy visualization of the spatially inhomogeneous state in the Dy_0.2Sr_0.8CoO_3-δ ceramic samples are presented and compared with the X-ray diffraction data.     

Structure and transport properties of donor-doped barium strontium cobaltites

In this work, Nb-substituted barium strontium cobaltites Ba_0.5Sr_0.5Co_1-xNb_xO_3-δ (x = 0 – 0.4) have been fabricated and studied. The structural analysis showed that the Nb content influences the lattice constant as well as the distance between the (Co, Nb) and oxygen atoms. The study of morphology of samples showed that the Nb content does not change the porosity, grain size and morphology of the ceramics. The total electrical conductivity was studied as a function of temperature and p_O2/p_H2O. It was shown, that total conductivity is influenced by the cobalt to niobium ratio while the conduction mechanism was similar in all analyzed samples. Transport properties and the presence of protonic conductivity were studied in a dry and humidified atmosphere. A non-negligible difference between total conductivities in dry and wet atmospheres below 500 °C was observed what indicates the presence of protonic defects in these structures. Hydrogenation as a predominant protons formation mechanism was proposed.     

Polarization origin and iron positions in indium doped barium hexaferrites

M-type hexaferrite BaFe_12?xIn_xO₁₉ (x = 0.1, 1.2) samples were investigated by high resolution neutron powder diffraction and vibration sample magnetometry in a wide temperature range of 4–730 K. Structural and magnetic parameters were determined including the unit cell parameters, ionic coordinates, thermal isotropic factors, occupation positions, bond lengths and bond angles, microstrain values and magnetic moments. In³⁺ cations may be located only in the Fe1 - 2a and Fe2 - 2b crystallographic positions with equal probability for the x = 0.1 sample. At x = 1.2 about half of In³⁺ cations occupy the Fe5 - 12k positions whilst the other half are equiprobably located in the Fe1 – 2a and Fe2 – 2b positions. The spontaneous polarization was observed for these compositions at 300 K. The influence of structural parameters on the temperature behavior of Fe³⁺(i) - O^2- - Fe³⁺(j) (i, j = 1, 2, 3, 4, 5) indirect superexchange interactions was established. With the substitution level increase the superexchange interactions between the magnetic positions inside and outside the sublattices are broken which leads to a decrease in the value of the corresponding magnetic moments.