金黄节杆菌CYC705腈水解酶催化亚氨基二乙酸合成的研究

将金黄节杆菌CYC705(Arthrobacter aurescens CYC705) 腈水解酶用于生物催化合成亚氨基二乙酸(IDA),从生物催化剂的形式、生物催化反应过程优化和反应体系放大三个方面进行了考察。在氨基载体固定化酶、环氧基载体固定化酶、海藻酸钠固定化细胞、壳聚糖固定化细胞和游离全细胞几种生物催化剂形式中,壳聚糖固定化细胞催化效率最高、稳定性最好。通过反应体系、反应温度、金属离子、底物浓度、固定化细胞投量等因素的优化,确定了最佳的生物催化反应条件：以50 mmol/L pH=6.6的磷酸氢二钠-柠檬酸缓冲液作为反应体系,底物亚氨基二乙腈(IDAN)的浓度为200 mmol/L,添加CoCl2至终浓度为1 mmol/L,反应温度37 ˚C,固定化细胞投量为0.25 g每5 mL反应体积。在此条件下,反应2h可将IDAN完全转化为IDA。进一步将反应体系放大10倍,催化200 mmol/L的IDAN完全转化为IDA仅需1h。     

Oxygen vacancy levels on gadolinia-doped ceria interlayer deposited by atmospheric pressure plasma jet for solid oxide fuel cells

The oxygen vacancy levels as a factor on different gadolinia-doped ceria interlayer (GDCi) films deposited on yttria stabilized zirconia (YSZ) electrolyte substrates by an atmospheric pressure plasma jet (APPJ) via precursor solution of nitrate salts are investigated. Focusing on the effect of carrier gases, scanning electron microscopy (SEM), Raman, and X-ray diffraction (XRD) are implemented for the materials characterization of the as-deposited GDCi films and sintered-GDCi films at various temperatures. The higher level of oxygen vacancies in GDCi films adhered on 8YSZ electrolyte are evidently analyzed using Ar as the carrier gas during the deposition, of which the interdiffusion resulted in the formation of (GDC + YSZ) solid solution for sintering over 1300?°C degraded the total conductivity. The deposition of GDCi films on 8YSZ by APPJ method using O₂ carrier gas significantly improved the total conductivities of the whole electrolyte layers. Moreover, this study provides the useful insight into the oxygen vacancy levels on GDC films as interlayer (GDCi) to improve the values of open circuit voltage in LSM/GDCi/YSZ/Pt full-cell, as well as offering the efficiency of APPJ as one step deposition process.     

The effect of the addition of carbon nanotube fluids to a polymeric matrix to produce simultaneous reinforcement and plasticization

Carbon nanotube (CNT) fluids with liquid-like behavior were synthesized and incorporated into a polymeric matrix to investigate the processability and mechanical performance of the resulting composite, as well as the distribution of CNTs in the host material. We demonstrated that the simultaneous reinforcement and plasticization effect on the polymeric matrix by the novel multifunctional component should be ascribed to the soft organic coating and the unique flowability of such surface-functionalized CNTs. The solvent- and plasticizer-free nature along with the above-mentioned advantages provides a green and efficient route to fabricate high performance composite materials.     

Avoiding structure degradation during activation of ordered mesoporous carbons

Hierarchical micro–mesoporous carbons with high porosity development and ordered structure were prepared. The innovative proposal consists in developing microporosity in ordered mesoporous carbon by chemical activation in template presence in order to minimize the structural damage. Thus, we have directly carried out the chemical activation of a mesoporous carbon/silica composite with KOH. The effect on mesoporous ordered structure of both KOH/carbon ratio and activation temperature has been studied. Following chemical activation the specific surface area is increased from 341 to 1757 m²/g and the micropore volume becomes almost six times larger than initial value. Although a slight widening of the mesopore distribution and an increase in the mesopore volume has been observed during activation, TEM and XRD results reveal an excellent conservation of the ordered mesoporous structure during activation even at conditions well above the limits that a CMK-3 type carbon can resist.     

Soybean oil‐based shape‐memory polyurethanes: Synthesis and characterization

Shape‐memory polymers (SMPs) have wide range of applications due to their ability to sense environmental stimuli and reshape from a temporary shape to a permanent shape. Plant oil‐based polymeric materials are highly concerned in recent years in consideration of petroleum depletion and environmental pollution. However, plant oil‐based polymers are rarely investigated regarding their shape‐memory characteristics though bio‐based SMPs are highly desired nowadays. In this study, a series of soybean oil‐based shape‐memory polyurethanes (SSMPUs) are prepared through a mild chemo‐enzymatic synthetic route, and their properties are fully characterized with tensile testing, DSC, dynamic mechanical analysis (DMA), and shape‐memory testing. Results show that SSMPUs are soft rubbers with tensile strength in the range of 1.9–2.2 MPa and glass transition temperature in the range of 2–5°C, and possess good shape recoveries at RT when stretching ratio is 10, 20, and 30%, respectively. This work would promote the development of high‐value‐added plant oil‐based shape‐memory polyurethanes. Practical applications: Using annual renewable plant oil as feedstock, the synthesized SSMPUs show good shape recovery properties, which will make them applicable as potential alternatives to petroleum‐based shape‐memory materials. The simple and mild preparation process also contributes to the further exploration of plant oil to value‐added functional materials.     

Synthesis and investigation of TiO2 nanotube arrays prepared by anodization and their photocatalytic activity

TiO₂ nanotube arrays were successfully prepared by anodic oxidation method in the electrolyte of ethylene glycol and deionized water mixed in 9:1 volumetric ration including 0.5 wt.% NH₄F. The microstructure and phase compositions of samples annealing from 0 °C to 800 °C were characterized by field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). FESEM showed that the obtained nanotubes with diameter 80–100 nm and length 4.89 μm were highly ordered and perpendicular to Ti substrate. The tubular structure collapsed at 680 °C. The photocatalytic activity of samples annealing at different temperature were calculated by the degradation of a model dye, methyl orange (MO), under UV light illumination. The results indicated the phase composition and the morphology of TiO₂ nanotubes both played an important role in the degradation of MO. In addition, the effects of initial solution pH and dye concentration on degradation of MO had also been investigated. As a result, the optimum values of calcination temperature, initial solution pH and dye concentration were found to be 550 °C, 3, 10 mg/l, respectively. The best photodegradation of MO was 76% under illumination for 3 h.     

Low temperature sintering of lead-free Bi0.5(Na0.82K0.18)0.5TiO3 piezoelectric ceramics by co-doping with CuO and Nb2O5

Effect of excess CuO additive on the sintering behavior and piezoelectric properties of Bi_0.5(Na₈₂K_0.18)_0.5TiO₃ ceramics was investigated. The addition of small amount of excess CuO as low as 1 mol% was quite effective to lower the sintering temperature (T_s) of BNKT ceramics down to 975 °C while their piezoelectric properties were degraded by Cu doping. However, the electric field-induced strain was markedly enhanced by further addition of Nb₂O₅ with CuO without elevating T_s. The normalized strain S_max/E_max of 427 pm/V was obtained with a specimen sintered with 0.02 mol CuO and 0.03 mol Nb₂O₅ in excess.     

The dependence of magnetic properties on temperature for rare earth ErCrO3 chromites

Multiferroic ErCrO₃ was synthesized and the detailed magnetic as well as ferroelectric properties were investigated. The dc magnetization shows that ErCrO₃ undergoes a antiferromagnetic ordering at T_N = 133 K due to the Cr³⁺–Cr³⁺ followed by weak ferromagnetic ordering. Around T_SR ≈ 22 K, ErCrO₃ exhibits a spin reorientation from Γ₄ to Γ₁. And the stability of the ferromagnetic Γ₄ phase increases with the applied magnetic field increasing. Furthermore, at lower temperature, it shows weak antiferromagnetic ordering of Er³⁺. We also present the low temperature polarization data for ErCrO₃ and find a remarkable decreasing of polarization around T_N = 133 K on increasing temperature, this effect might be due to the coupling between magnetic and ferroelectric order parameters, and the magnetic field suppresses the polarization which demonstrates convincingly the strong magnetoelectric (ME) coupling in ErCrO₃.     

响应面优化改进硫脲法浸出炼锌渣中银的工艺

采用改进硫脲法浸出含硫铁矿炼锌渣中银,用响应面方法研究了双氧水浓度［X1/（mol·L-1）］、硝酸浓度［X2/（mol·L-1）］、硫脲浓度［X3/（mol·L-1）］和浸出温度（X4/℃）对银浸出率（Y/%）的影响,并优化了浸出工艺。银浸出率与工艺因素之间的关系符合二次模型：Y=-476.0-40.17X1+58.20X2+82.15X3+12.30X4-22.65X1X3+5.03X1X4-0.51X2X4-1.08X3X4-81.47X12-3.65X22-1.30X32- 0.11X42。双氧水浓度和硫脲浓度的一次项对浸出率的影响不显著,浸出温度的一次项、双氧水浓度和硫脲浓度的二次项对浸出率有着显著影响,硝酸初始浓度的一次项和二次项对浸出率有着高度显著影响。双氧水浓度与硫脲浓度,温度与双氧水浓度、硝酸浓度、硫脲浓度之间均存在高度显著的交互作用。模型拟合所得最优的浸出条件为：双氧水浓度为0.96 mol/L、硝酸浓度为4.12 mol/L、硫脲浓度为2.17 mol/L、浸出温度为55 ℃。此条件下,银浸出率为91.3%,接近模型预测值（92.7%）。与单因素实验相比,银浸出率提高近10%。