Kinetic model of 4-CP degradation by Fenton/O2 system

A kinetic model of the degradation of 4-CP by Fenton/O(2) system was established, in which particular attention was paid to the role of oxygen in the process because many former researches suggested that the presence of oxygen could decrease the input of H(2)O(2). The proposed model well predicted 4-CP degradation and H(2)O(2) consumption by Fenton/O(2) and Fenton/N(2) systems at varying levels of Fe(2+), H(2)O(2), and 4-CP input. Most correlation coefficients between experimental and predicted data of 4-CP and H(2)O(2) concentration were above 0.95. The model could predict the enhancement of 4-CP degradation by oxygen and the difference in the evolution of aromatic intermediates between Fenton/O(2) and Fenton/N(2) system. The predicted and experimental data both showed the degree of benzene ring cleavage in Fenton/O(2) system was higher than that in Fenton/N(2) system. Understanding the role of oxygen is very important to improve the decomposition performance.     

The extreme xerophilic mould Xeromyces bisporus--growth and competition at various water activities

Little is known about the mould, Xeromyces bisporus, unique in its strong xerophilicity and ability to grow at water activity (a_w) 0.62, lower than for any other known organism. The linear growth rates of one fast and one slow-growing strain of X. bisporus were assessed at 20, 25, 30 and 37 °C on solid agar media containing a mixture of glucose and fructose to reduce a_w to 0.94, 0.88, 0.84, 0.80, 0.76 and 0.66. Growth rates of xerophilic species closely related to X. bisporus, viz. Chrysosporium inops, C. xerophilum and Monascus eremophilus, were also assessed. Optimal conditions for growth of both X. bisporus strains were approx. 0.84 a_w and 30 °C, despite FRR 2347 growing two- to five-fold faster than CBS 185.75. X. bisporus FRR 2347 even grew well at 0.66 a_w (0.48 mm/day). C. inops and C. xerophilum were more tolerant of high a_w than X. bisporus, and could be differentiated from each other based on: the faster growth of C. xerophilum; its preference for temperatures ≥ 30 °C and a_w ≥ 0.94 (c.f. ≤ 25 °C and ~ 0.88 a_w for C. inops); and its ability to grow at 0.66 a_w, which is the lowest a_w reported to date for this species. M. eremophilus grew slowly (max. 0.4 mm/day) even in its optimal conditions of ~ 0.88 a_w and 25 °C. To investigate the competitive characteristics of X. bisporus at low a_w, both X. bisporus strains were grown in dual-culture with xerotolerant species Aspergillus flavus and Penicillium roqueforti, and xerophilic species A. penicillioides, C. inops, C. xerophilum and Eurotium chevalieri, on glucose-fructose agar plates at 0.94, 0.84, 0.80 and 0.76 a_w and at 25 °C. Growth rates and types of interactions were assessed. Excretion of inhibitory substances acting over a long-range was not observed by any species; inhibitors acting over a short-range that temporarily slowed competitors' growth or produced a protective zone around the colony were occasionally observed for A. penicillioides, C. inops and C. xerophilum. Instead, rapid growth relative to the competitor was the most common means of dominance. The xerotolerant species, A. flavus and P. roqueforti were dominant over X. bisporus at 0.94 a_w. E. chevalieri was often dominant due to its rapid growth over the entire a_w range. At a_w < 0.80, X. bisporus was competitive because it grew faster than the other species examined. This supports the concept that its ideal environmental niche is sugary foods with low a_w.     

On the long-term stability of Pd-membranes with TiO2 intermediate layers for H2 purification

This work addresses the use of TiO₂-based particles as an intermediate layer for reaching fully dense Pd-membranes by Electroless Pore-Plating for long-time hydrogen separation. Two different intermediate layers formed by raw and Pd-doped TiO₂ particles were considered. The estimated Pd-thickness of the composite membrane was reduced in half when the ceramic particles were doped with Pd nuclei before their incorporation onto the porous support by vacuum-assisted dip-coating. The real thickness of the top Pd-film was even lower (around 3 μm), as evidenced by the cross-section SEM images. However, a certain amount of palladium penetrates in some points of the porous structure of the support up to 50 μm in depth. In this manner, despite saving a noticeable amount of palladium during the membrane fabrication, lower H₂-permeance was found while permeating pure hydrogen from the inner to the outer surface of the membrane at 400 °C (3.55·10^?4 against 4.59·10^?4 mol m^?2 s^?1 Pa^?0.5). Certain concentration-polarization was found in the case of feeding binary H₂–N₂ mixtures for all the conditions, especially in the case of reaching the porous support before the Pd-film during the permeation process. Similarly, the effect of using sweep gas is more significant when applied on the side where the Pd-film is placed. Besides, both membranes showed good mechanical stability for around 200 h, obtaining a complete H₂/N₂ ideal separation factor for the entire set of experiments. At this point, this value decreased up to around 400 for the membrane prepared with raw TiO₂ particles as intermediate layer (TiO₂/Pd). At the same time, complete selectivity was maintained up to 1000 h in case of using doped TiO₂ particles (Pd–TiO₂/Pd). However, a specific decrease in the H₂-permeate flux was found while operating at 450 °C due to a possible alloy between palladium and titanium that is not formed at a lower temperature (400 °C). Therefore, Pd–TiO₂/Pd membranes prepared by Electroless Pore-Plating could be very attractive to be used under stable operation in either independent separators or membrane reactors in which moderate temperatures are required.     

考虑中间主应力的非均匀应力场圆形巷道围岩塑性区分析

基于Drucker-Prager准则,引入中间主应力系数,推导出不同侧压系数下巷道围岩塑性区边界线方程,用于预测不同侧压系数下巷道围岩塑性区的大小和形状。用单因素分析法,考虑不同中间主应力下,巷道围岩塑性区半径的变化规律。在侧压系数λ=1的时候,对在D-P准则下和在Mohr-Coulomb准则下巷道围岩塑性区的大小进行比较。侧压系数越偏离于1,巷道围岩塑性区水平方向和垂直应力侧差异增加,对围岩塑性区的大小和形状影响也越大;随中间主应力增大,塑性区范围越小。     

Syngas production at intermediate temperature through H2O and CO2 electrolysis with a Cu-based solid oxide electrolyzer cell

Solid Oxide Electrolyzer Cells (SOECs) are promising energy devices for the production of syngas (H₂/CO) by H₂O and/or CO₂ electrolysis. Here we developed a Cu–Ce_0.9Gd_0.1O_2−δ/Ce_0.8Gd_0.2O_2−δ/Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ-Ce_0.8Gd_0.2O_2−δ cell and performed H₂O and CO₂ electrolysis experiments in the intermediate temperature range (600°C–700 °C). As a baseline, the cell was first tested in fuel cell operation mode; the sample shows a maximum power density peak of 104 mW cm⁻² at 700 °C under pure hydrogen and air. H₂O electrolysis testing revealed a steady production of hydrogen with a Faraday's efficiency of 32% at 700 °C at an imposed current density of −78 mA cm⁻². CO production was observed during CO₂ electrolysis but higher cell voltages were required. A lower efficiency of about 4% was obtained at 700 °C at an imposed current density of −660 mA cm⁻². These results confirm that syngas production is feasible by water and carbon dioxide electrolysis but further improvements from both the manufacturing and the electrocatalytic aspects are needed to reach higher yields and efficiencies.     

Electrochemical performance of a mechanochemically prepared submicron-sized crystalline Nd1.8Ce0.2CuO4±δ cathode for intermediate temperature solid oxide fuel cells

To produce a Nd_1.8Ce_0.2CuO_4±δ solid solution, the oxide form of the reagents were milled for 36 h and sintered at 1173 K for 8 h in a microwave furnace. The transition from a negative temperature coefficient (NTC) of conductivity to a positive temperature coefficient (PTC) was suppressed due to the submicron size of the crystallites. The low-frequency response in the complex impedance plane fit the Gerischer element. At 973 K, the area specific resistance (ASR) of Nd_1.8Ce_0.2CuO_4±δ/GDC/Nd_1.8Ce_0.2CuO_4±δ sintered at 1073 K for 2 h was 1.92 ohm cm².     

Intermediate mass dilepton production during the chemical equilibration of quark gluon plasma

The production of dileptons from the chemically equilibrating quark gluon plasma in the intermediate mass region has been studied.Comparing with the calcuated results based on the thermodynamic equilibrium system of quark gluon plasma,it has been found that the quark phase of the chemically equilibrating system gives rise to an even larger enhancement of the dileptons production.Therefore.such an enhancement of dilepton production may signal the formation of quark gluon plasma.     

锅炉用15Mo3钢板的试测与研究

本文对１５Ｍｏ３钢冶成分的选定，生产工艺，中温性能、Ｚ向性能，钢的组织检验以及合适的正火温度的选择作了全面的分析。     

Effect of concentration,ionic strength and freeze-drying on the heat-induced aggregation of soy proteins

The effects of protein concentration, ionic strength, and lyophilization on heat-induced aggregation of soy proteins were analyzed by SDS-PAGE, SEC-HPLC and laser light scattering (LLS). SDS-PAGE profile suggested that the aggregates were formed via non-covalent forces and/or disulfide bonds. At ionic strength of zero, SEC-HPLC revealed that the samples were composed of three major fractions: aggregates, intermediate fractions and non-aggregated molecules. Furthermore, the relative proportion of the aggregate fraction increased as protein concentration increased. Similarly, LLS indicated that the average hydrodynamic radius (R_h) increased at higher protein concentration. In sample with an ionic strength of zero, the intermediate fraction decreased after freeze-drying with a concomitant increase of the aggregate fraction. When the sample was heated at elevated ionic strength, the SEC-HPLC and LLS profiles changed substantially, the intermediate fractions decreased, and lyophilization had effect on the fraction of aggregates. These experiments suggest novel strategies for producing soy protein aggregates with controlled properties.     

热装轴管中频感应加热设备的设计与研制

介绍了一种新型的车桥轴管热装配感应加热设备 分析了该设备中频电源电路的工作原理 ,提供了主要设计参数 ,运用CAD技术对主电路进行运算 ,绘出仿真图并对比实验结果验证了设计方案 为推广节能环保型的热装工艺提供参考