Improving the Mixing Performances of Rice Straw Anaerobic Digestion for Higher Biogas Production by Computational Fluid Dynamics (CFD) Simulation

As a lignocellulose-based substrate for anaerobic digestion, rice straw is characterized by low density, high water absorbability, and poor fluidity. Its mixing performances in digestion are completely different from traditional substrates such as animal manures. Computational fluid dynamics (CFD) simulation was employed to investigate mixing performances and determine suitable stirring parameters for efficient biogas production from rice straw. The results from CFD simulation were applied in the anaerobic digestion tests to further investigate their reliability. The results indicated that the mixing performances could be improved by triple impellers with pitched blade, and complete mixing was easily achieved at the stirring rate of 80 rpm, as compared to 20–60 rpm. However, mixing could not be significantly improved when the stirring rate was further increased from 80 to 160 rpm. The simulation results agreed well with the experimental results. The determined mixing parameters could achieve the highest biogas yield of 370 mL (g TS)^?1 (729 mL (g TS_digested)^?1) and 431 mL (g TS)^?1 (632 mL (g TS_digested)^?1) with the shortest technical digestion time (T ₈₀) of 46 days. The results obtained in this work could provide useful guides for the design and operation of biogas plants using rice straw as substrates.     

推荐一个与材料相关的综合化学实验——醋酸酯淀粉的制备和表征

以淀粉和醋酸酐为原料,在吡啶中反应制备醋酸酯淀粉,并用溶解性、相对分子质量、取代度、红外光谱、示差扫描量热分析、X射线衍射分析及扫描电镜等表征醋酸酯淀粉,使学生学会醋酸酯淀粉制备和一些表征技术,了解化学原理和实验技术在材料科学中的应用,为进一步理解化学在材料、环境及生命等学科领域的中心学科作用打下基础。     

Effect of Cu promoter on Ni-based SBA-15 catalysts for partial oxidation of methane to syngas

A series of Ni/SBA-15 catalysts with 5wt% to 15wt% Ni content as well as a series of 12.5%Ni/Cu/SBA-15 catalysts with 1% to 10% copper content were prepared by the impregnation method. The catalytic performance for partial oxidation of methane was investigated in a continuous flow microreactor under atmospheric pressure. The textural and chemical properties of the catalysts were characterized by XRD, TEM, BET and H2-TPR techniques. The results indicated that the catalysts modified with Cu promoter showed better performance than those without modification. For the 12.5%Ni/2.5%/Cu/SBA-15 catalyst, at 850 ◦C the conversion of CH4 reached 97.9% and the selectivity of CO and H2 reached 98.0% and 96.0%, respectively. In XRD patterns of the Ni/Cu/SBA-15 catalyst with 7.5 to 10% Cu contents there were CuO characteristic peaks beside NiO characteristic peaks. The mesoporous structure of SBA-15 was retained in all of the catalysts. TPR analysis of the catalysts revealed that a strong interaction between Ni, Cu promoter and SBA-15 support may be existed. This interaction enhanced significantly the redox properties of the catalysts resulting in the higher catalytic activity.     

超高效液相色谱-四极杆飞行时间质谱法非靶向快速筛查进口粮谷中未知的农药残留

利用快速提取农药(fast pesticide extraction,FaPEx)方法前处理样品,并结合超高效液相色谱-四极杆飞行时间质谱(UPLC-Q-TOF)技术建立了非靶向快速筛查进口粮谷中未知的多种农药残留方法。采用1%(v/v)醋酸乙腈溶液提取粮谷中未知的农药残留,FaPEx固相萃取柱净化、浓缩,UPLC-Q-TOF检测。利用目标化合物特征离子的精确质量数、同位素匹配、二级碎片信息和保留时间进行数据库匹配,筛查可疑未知农药。结果表明,该方法无需对照标准品即可快速筛查进口粮谷中的农药残留,能够应用于进口粮谷样品的实际筛查。该方法快速、准确、分析通量高,可以为进口粮谷中农药残留的快速筛查和质量控制提供重要的方法依据。     

基于肝脏代谢组分析研究低聚硒化氨基多糖对黑鲷的免疫调节作用

采用基于液相色谱-飞行时间质谱联用（LC-TOF-MS）技术的代谢组学方法，分析黑鲷肝脏内源性代谢物的变化，研究硒化氨基多糖增强黑鲷的免疫调节机制。采用XCMS^plus软件非靶向分析质谱采集数据，筛选潜在生物标志物，并通过MetaboAnalyst3.0网站分析相关代谢通路。结果表明，饲喂硒化氨基多糖组中的代谢物明显区分于空白组，发现并鉴定了32个有差异的生物标志物。代谢通路分析结果表明，硒化氨基多糖可通过氨基酰基-转运脱氧核糖核苷酸（tRNA）生物合成、氨基酸代谢、核苷酸代谢、氮代谢等代谢通路增强黑鲷自身的免疫机能。该研究为阐明硒化氨基多糖的免疫增强机制提供了科学依据。     

Effect of Ni Loading and CexZr1-xO2 Promoter on Ni-Based SBA-15 Catalysts for Steam Reforming of Methane

A series of Ni/SBA-15 catalysts with Ni contents ranging from 5wt% to 20wt% as well as 10wt%Ni/10wt?xZn-xO2/SBA-15 (z=0, 0.5, 1) were prepared. The structures of the catalysts were characterized using XRD, TPR, TEM and BET techniques. The catalytic activities of the catalysts for steam reforming of methane were evaluated in a continuous flow microreactor. The results indicated that both the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts had good catalytic activities at atmospheric pressure. The 10wt%Ni/SBA-15 catalyst exhibited excellent stability at 800癈 for time on stream of 740 h. After the reaction, carbon deposits were not formed on the surface of the catalyst. There existed a regular hexagonal mesoporous structure in the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts. The nickel species and the CexZr1-xO2 component were all confined in the SBA-15 mesopores. The CexZr1-xO2 could promote dispersion of the nickel species in the Ni/CexZr1-xO2/SBA-15 catalysts.     

用水合肼还原的Ru／AC氨合成催化剂的制备

 用RuCl3水溶液浸渍BET比表面积为1020m2／g的椰壳活性炭（AC）载体，制备了钌含量为6％的Ru／AC氨合成催化剂．在添加助剂前，分别用水合肼水溶液、水合肼蒸气和H2还原催化剂，然后分别浸渍Ba（NO3）2和KOH．催化剂中的Ru∶K∶Ba摩尔比为1∶3∶0．3．用N2物理吸附、XPS和CO化学吸附等方法对催化剂进行了表征．结果表明，用不同还原方法制备的催化剂上的钌以不同的化学状态存在，它的活性与其比表面积和金属钌的分散度相关．用水合肼水溶液还原的催化剂S1中的钌在大气气氛下以金属态存在，它的BET比表面积和金属分散度较大，低温低压下催化活性最高．以水合肼蒸气还原的催化剂S2中的钌在大气气氛下以RuO3形态存在，它的BET比表面积和金属分散度小，催化活性最低．用H2还原的催化剂S3中的钌在大气气氛下以RuO2形态存在，其BET比表面积和金属分散度与S1催化剂相当，催化活性也与S1相近．     

Preparation and Characterization of Carbon Nanotubes-Coated Cordierite for Catalyst Supports

The carbon nanotubes-coated cordierite (CNTs-cordierite) was fabricated by pyrolysis of ethine on cordierite with iron catalyst, which was penetrated into the cordierite substrate by vacuum impregnation. The cordierite substrate, carbon naontubes, and CNTs-cordierite were characterized by SEM. TEM/HREM. BET, and TGA. The results show that the carbon nanotubes were distributed uniformly on the surface of cordierite. A significant increase in BET surface area and pore volume was observed, and a suitable pore-size distribution was obtained. On the CNTs-cordierite, carbon nanotubes penetrated into the cordierite substrate, which led to a remarkable stability of the CNTs against ultrasound maltreatment. Growth time is an important factor for thermostability and texture of the sample. The mass increased but the purity decreased with the growth time, which caused the exothermic peak shift to low temperature, and the corresponding full width half maximum (FWHM) of the peak in DTG increased.     

Rapid quantification of four major bioactive alkaloids in Corydalis decumbens (Thunb.) Pers. by pressurised liquid extraction combined with liquid chromatography-triple quadrupole linear ion trap mass spectrometry

A new method based on pressurised liquid extraction (PLE) followed by liquid chromatography-triple quadrupole linear ion trap mass spectrometry (LC-QTrap-MS) analysis has been developed for the identification and quantification of four major alkaloids in extracts of Corydalis decumbens (Thunb.) Pers. PLE extractions were performed using 90% ethanol; temperature was set at 100 °C and pressure at 1500 psi. HPLC analysis was performed on a Waters XBridge™ C₁₈ column (150 mm × 2.1 mm i.d., 3.5 μm) eluted by a mobile phase of acetonitrile and 0.2% acetic acid. Data acquisition was carried out in multiple reaction monitoring transitions (MRMs) mode, monitoring two MRM transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the enhanced product ion modus (EPI) of the linear ion trap. The novel LC-QTrap-MS platform offers the best sensitivity and specificity for characterization and quantitative determination of the four alkaloids in C. decumbens (Thunb.) Pers. and fulfils the quality criteria for routine laboratory application.     

基于C-H键活化的铜催化二苄胺氧化酰胺化反应

基于铜催化的C-H键活化构建了一类高效的二苄胺氧化酰基化生成N-苄基苯甲酰胺的反应. 该反应使用CuBr作为催化剂, 二乙酸碘苯作为氧化剂, 在温和条件下生成两种酰胺, 总产率最高可达92.0%. CuBr催化剂价廉易得, 催化活性高. 同时这也是首次使用二乙酸碘苯作为氧化剂, 通过二苄胺的直接氧化酰基化反应合成N-苄基苯甲酰胺.