Single-Crystal Growth of BaFe<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>Co<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>As<Subscript>2</Subscript> Without Fluxing Agent

We report a simple, reliable method to grow high-quality BaFe_2−x Co _x As₂ single-crystal samples without using any fluxing agent. The starting materials for the single-crystal growth come from well-crystallized polycrystalline samples and the highest growing temperature can be 1230°C. The as-grown crystals have typical dimensions of 4×3×0.5 mm³ with c-axis perpendicular to the shining surface. We find that the samples have very large current carrying ability, indicating that the samples have good potential technological applications.     

板带轧机的发展历史与现状

简要阐述了板、带轧机的发展历程,从轧机的辊系、牌坊、传动方式、电机、压下系统、控制系统等变化作为出发点,展开讨论,并在分析牌坊变化一例中结合ANSYS分析软件对其两种不同的板式牌坊进行力学分析比较,最后展望了板、带轧机的发展趋势。     

常压H2气氛烧结W-TiC合金的致密化行为和性能

采用粉末冶金方法在常压H2气氛下制备W-TiC合金,研究W-TiC合金的烧结致密化行为,并对合金的性能和组织结构进行分析.结果表明:添加微量强化烧结元素可改善W-TiC合金的烧结活性,在1700℃烧结120min后其相对密度达到99.2％;随着烧结温度的升高,W-TiC合金的拉伸强度提高,在2000℃烧结120 min...     

泥岩顶板巷道遇水冒顶机理与支护对策分析

针对煤层巷道开挖和维护过程中,泥岩顶板遇水导致围岩承载性能恶化,易于引起顶板冒顶的特点,以梅花井煤矿112201工作面机巷为例,采用现场实测、实验室试验、理论分析和数值模拟相结合的方法分析了该类顶板易于发生冒顶的机理,研究发现该类顶板发生冒顶前已发生明显离层,顶板锚固体呈现整体垮冒的特点;泥岩组分中富含黏土矿物是产生崩...     

Immunochromatography for the rapid determination of cadmium concentrations in wheat grain and eggplant

BACKGROUND: A simple and quick on‐site test for trace levels of cadmium (Cd) in food is needed because of the human toxicity of this heavy metal. We developed an immunochromatography kit which uses the antigen‐antibody complex reaction between the Cd–ethylenediaminetetraacetic acid (Cd–EDTA) complex and an anti‐Cd–EDTA antibody. We previously reported the successful use of this kit to determine Cd concentrations in brown rice with respect to the international standard: 0.4 mg kg^?1. Here, we measured, using this immunochromatography kit, Cd concentrations in crops with lower international standards than rice. RESULTS: Cadmium extracted with 0.1 mol L^?1 HCl from wheat grain and fresh eggplant was purified sufficiently using an ion‐exchange column treatment. Appropriate HCl extraction rates and dilution rates for the column eluate were selected; Cd concentrations in wheat grain and fresh eggplant were determined successfully by immunochromatography with respect to the international standards of 0.2 mg kg^?1 and 0.05 mg kg^?1 fresh weight, respectively. CONCLUSION: Approximate Cd concentrations in wheat grain and fresh eggplant can be monitored easily and quickly by this method at locations where facilities for acid digestion and precision analysis are not available. Copyright © 2011 Society of Chemical Industry     

Influence of Ni2+ and Co2+ on methanogenic activity and the amounts of coenzymes involved in methanogenesis

The requirement of Ni2+ and Co2+ addition on methanogenic activity and the coenzymes involved in methanogenesis were investigated in anaerobic continuous cultivation with synthetic wastewater using acetate as the sole carbon source. Addition of Ni2+ and Co2+ to the synthetic wastewater drastically increased the maximum dilution rate of the cultivation. The concentrations of coenzymes F430 and corrinoids in the biomass increased to 0.62 micromol-Ni/g-VSS and 0.67 micromol-Co/g-VSS, respectively with the increase of the dilution rate. Methanogenic activity of the culture broth also increased with an increase of dilution rate. However, without addition of Ni2+ and Co2+, F430 and corrinoids were not detected in the biomass and methanogenic activity was only a trace level at a dilution rate of 0.025 d(-1). When the amounts of Ni2+ and Co2+ added at a dilution rate of 0.6 d(-1) were lowered in steps, the concentrations of F430 and corrinoids in the biomass and methanogenic activity decreased with decreasing amounts of Ni2+ and Co2+ added. These results suggest that Ni2+ and Co2+ were required for the methane-producing reactions via increases of coenzymes F430 and corrinoids.     

高效液相色谱法检测水产品中双酚A及其蓄积特征研究

目的 建立一种利用高效液相色谱(high performance liquid chromatography, HPLC)联用紫外(ultraviolet absorption detector, UV)检测器检测水产品中双酚A (bisphenol A, BPA)蓄积量的分析方法并探究BPA的蓄积特征研究。方法 根据线性、极限检测、精密度和回收率等标准对该分析方法进行了验证。采用不同浓度BPA胁迫常见海洋底栖动物-单环刺螠(Urechis unicinctus),以二氯甲烷作为萃取剂,对单环刺螠肌肉进行前处理,用上述HPLC方法检测。结果 在所建立的检测条件下,采用内标外标法定量 ,BPA在质量浓度0~10 mg/L范围,浓度与峰面积呈显著正相关(r＝0.9998,P<0.01),检出限(the limit of detection,LOD)为0.247 mg/L,定量限(the limit of quantification,LOQ)为0.464 mg/L,加标回收率为99.68%,日间精密度(relative standard deviation,RSD)为2.2121.28%。单环刺螠肌肉内BPA蓄积量随着暴露浓度的增加而上升,各浓度处理组BPA蓄积量随胁迫时间的延长呈现先降后升趋势。结论 该HPLC检测方法可以检测出水产品中μg/g级BPA含量,操作简便,可用于水产品质量安全检测。BPA在单环刺螠肌肉内蓄积量随暴露时间延长,先降低后上升,具有潜在的水产品安全风险。     

聚磁式场调制永磁风力发电机工作原理与静态特性

提出一种新型聚磁式场调制永磁(Flux-Concentrating Field-Modulated Permanent-Magnet,FCFMPM)电机,该电机外转子采用聚磁式永磁体结构改善气隙磁通密度,定子采用开口槽结构提高空间利用率.基于磁齿轮效应,定子齿对转子永磁磁场进行调制,产生极对数少、运行速度快的谐波磁场,由该谐波磁场作为有效励磁的FCFMPM电机具有低速、大转矩密度的特点.在深入分析电机工作原理的基础上,运用二维有限元方法计算了其静态特性,包括空载永磁磁链、空载感应电动势、电感、定位力矩和电磁转矩等.研制了一台5kW实验样机,并与商业化小型永磁直驱风力发电机做比较.仿真和实验结果表明,所提电机具有转矩密度大、定位力矩小、外特性硬等特点,特别适用于如风力发电等低速、直驱系统.     

茶蜂花粉提取物BPE对LPS诱导的Raw 264.7细胞的体外抗炎症作用

以茶蜂花粉提取物(BPE)为实验材料,研究了其可能的抗炎活性。通过福林酚法和三氯化铝比色法测定BPE中的总酚酸和总黄酮质量分数,ABTS自由基清除实验评价BPE体外自由基清除能力,并采用LPS诱导的小鼠Raw 264.7细胞体外炎症模型,探究BPE对炎症因子和相关基因表达的调控作用。结果显示,BPE的总酚酸及总黄酮质量分数分别为(255.23±21.43)mg/g(绿原酸当量)和(132.85±14.77)mg/g(芦丁当量);BPE的ABTS自由基清除力的IC_(50)值为(53.9±5.38)μg/m L;在体外抗炎实验中,BPE能显著抑制Raw 264.7细胞NO的释放,显著抑制i NOS、IL-1β和IL-10,增强HO-1基因mRNA水平的表达,并呈一定的剂量相关性。表明,BPE富含黄酮和酚酸类物质并具有很强的自由基清除能力,在体外细胞实验中表现出了良好的抗炎症效果。     

Characterization,Stability, and In Vitro Release Evaluation of Carboxymethyl Chitosan Coated Liposomes Containing Fish Oil

Fish oil was extracted and refined from Nile tilapia viscera. Uncoated liposomes (un‐L) and carboxymethylchitosan (CMCS)‐coated liposomes (CM‐L) containing fish oil were prepared, and their characteristics, stability, and release in vitro were studied. The CMCS coating increased the mean diameter of liposomes but there was no effect on entrapment efficiency. The surface structure and characteristics of liposomes were determined. The Fourier transform infrared spectroscopy showed that the hydrogen bonding formed between the CMCS and the carbonyl region of the liposomes’ bilayer. The transition temperature of CM‐L was higher than un‐L. The stabilities of un‐L and CM‐L stored at 4 °C were better than 25 °C. Moreover, the CM‐L was significantly more stable than un‐L when stored at 25 °C. The release behaviors of un‐L and CM‐L were governed by 2 distinct stages and the first‐order model was the most suitable model for the whole release procedure. The diffusion and erosion may be the main release mechanisms for the full controlled release of fish oil from the liposomes. This study can provide theories and practice information for further applications of fish oil from tilapia viscera.