Magnetic interactions in a proposed diluted magnetic semiconductor(Ba_(1-x)K_x)(Zn_(1-y)Mn_y)_2P_2

By using first-principles electronic structure calculations, we have studied the magnetic interactions in a proposed BaZn2P2-based diluted magnetic semiconductor（DMS）. For a typical compound Ba（Zn（0.944）Mn（0.056））2P2 with only spin doping, due to the superexchange interaction between Mn atoms and the lack of itinerant carriers, the short-range antiferromagnetic coupling dominates. Partially substituting K atoms for Ba atoms, which introduces itinerant hole carriers into the p orbitals of P atoms so as to link distant Mn moments with the spin-polarized hole carriers via the p–d hybridization between P and Mn atoms, is very crucial for the appearance of ferromagnetism in the compound. Furthermore, applying hydrostatic pressure first enhances and then decreases the ferromagnetic coupling in（Ba0.75 K0.25）（Zn（0.944）Mn（0.056））2P2 at a turning point around 15 GPa, which results from the combined effects of the pressure-induced variations of electron delocalization and p–d hybridization. Compared with the BaZn2 As2-based DMS, the substitution of P for As can modulate the magnetic coupling effectively. Both the results for BaZn2 P2-based and BaZn2As2-based DMSs demonstrate that the robust antiferromagnetic（AFM） coupling between the nearest Mn–Mn pairs bridged by anions is harmful to improving the performance of these Ⅱ–Ⅱ–Ⅴ based DMS materials.

Safety Evaluation of a Compound Lonicera rupicola Hook.f. et & Thomson Injection

Safety of a compound Lonicera rupicola Hook. f. et & Thomson injection was evaluated by local irritation experiments including conjunctiva,skin and muscle irritant experiments,and the effect on weight gain was studied. The results showed that the compound L. rupicola Hook. f. et & Thomson injection had no irritation to rabbit eyes and weak irritation to rabbit ears,and had relatively strong irritation to the leg muscles of the mice. Its metabolism in mice had no abnormal toxicity.

Microstructure characteristics and mechanical properties of Al/Mg joints manufactured by magnetic pulse welding

The effective connection of 1050 Al and AZ31 Mg was realized by magnetic pulse welding.The maximum tensile-shear force of the dissimilar Al/Mg metal lap joint reached 97%of that of the 1050 Al alloy base material by optimizing the process parameters.The microstructure of dissimilar Al/Mg welded joints was analysed by Scanning Electron Microscope(SEM),Energy Dispersive Spectrometer(EDS)and Electron Backscattered Diffraction(EBSD).The results show that the key to obtaining high shear strength of Al/Mg dissimilar metal joints is mainly due to the following two reasons.On the one hand,grain refinement and element interdiffusion occur at the interface.On the other hand,no intermetallic compounds are formed at the interface.

基于复合纳米材料比色/荧光双信号的黄曲霉毒素B_1检测

以黄曲霉毒素B_1(aflatoxin B_1,AFB_1)为检测目标物,使用二氧化硅纳米颗粒为载体富集谷胱甘肽和黄曲霉毒素适配体制备识别探针,二氧化锰纳米颗粒与石墨烯量子点偶联的复合纳米材料为底物,通过谷胱甘肽与底物的反应构建了一种比色和荧光双模信号输出的高灵敏便携式检测平台。在优化条件下,对本方法的检测性能及特异性进行研究,得到比色信号的回归方程为ΔA=-0.275-0.021lg C,检出限为2.732×10^(-12) g/m L;荧光信号的回归方程为ΔF=928.733+71.779lg C,检出限为1.667×10^(-12) g/m L,两种方法都具备良好检测特异性。将该方法用于牛奶、大米、麦片、酱油和白醋5种实际样品中AFB_1的检测,并与传统方法进行对比,本方法结果具有较高的准确度。

荧光免疫分析技术检测食品中AFB1的研究进展

从不同的检测原理出发,将用于黄曲霉毒素B1的荧光免疫分析检测法分为4类:荧光免疫吸附法,基于荧光纳米颗粒的侧流免疫分析法,免疫磁分离荧光检测法和适配体免疫荧光分析法。总结荧光免疫技术检测食品中黄曲霉毒素B1的研究进展,并对需要克服的问题进行探讨,分析并展望其未来的发展趋势。

基于纳米材料改良酶联免疫吸附法的研究进展

文章重点总结了近年来基于纳米材料作为传统生物酶代替物,作为比色、荧光、电化学、光热效应、表面增强拉曼散射以及化学发光的信号底物构建的改良型ELISA;对改良型ELISA发展方向以及所面临的挑战进行了分析,并展望了其应用前景。

纳米工艺SRAM单元的尺寸效应研究与优化

集成电路工艺尺寸减小至纳米级时,尺寸效应的出现会导致SRAM读写可靠性下降。针对传统六管SRAM单元,采用蝶形曲线法对尺寸效应进行了分析,对不同工艺尺寸(90 nm^7 nm)的静态噪声容限进行了研究。分析了漏极致势垒降低效应、反向短沟道效应、正/负偏压温度不稳定性效应等物理效应,据此拟合出一个静态噪声容限经验公式。最后,对SRAM单元尺寸效应进行了优化,提高了SRAM单元的稳定性。

1200V场终止型绝缘栅双极晶体管的ADE物理建模及参数提取

绝缘栅双极晶体管(IGBT)是微电子学研究的热点之一,而相关电路仿真迫切需要该器件的等效模型.本文提出基于傅里叶解双极扩散方程(ADE)的1200V场终止型IGBT物理模型,通过RC电路等效漂移区载流子分布,精确求解双极扩散方程.该模型针对大功率IGBT的工作原理,采用大注入假设条件,在综合分析场终止层的同时,根据1200V场终止型IGBT的特点考虑漂移区载流子的复合效应.在提取器件模型所需的关键参数后,用实际IG-BT的测量结果对该模型的仿真结果进行了验证,通过分析静态以及关断瞬态特性曲线,仿真与实验数据误差均值小于8%,证明所建模型及参数提取方法的精确度.

Analysis of the Drug Sensitivity of Escherichia coli Isolated from Sheep in Yangling,Shaanxi Province

This study was conducted to investigate the drug sensitivity of Escherichia coli isolated from sheep, providing data reference for clinical medication. Fifty-four samples were collected from a certain sheep farm in Yangling, Shaanxi Province for E. coli isolation and identification, and K-B disk diffusion method was used to carry out the dug sensitivity test of 40 E. coli to the eight antimicrobials of spectinomycin, amikacin, tobramycin, enrofloxacin, nalidixic acid, levofloxacin, salafloxacin and ciprofloxacin. The results showed that there were 40 positive E. coli strains and the isolation rate was 74.7%. The resistance rates of the 40 E. coli to spectinomycin, amikacin,tobramycin and nalidixic acid were 85%, 95%, 97.5% and 87.5%, respectively, while the resistance rate to enrofloxacin, levofloxacin, salafloxacin and ciprofloxacin were relatively low and the resistance rates were 35%, 20%, 25% and 17.5%, respectively. The isolates showed different levels of drug resistance to eight antimicrobials and the highest resistance rate was 97.5%. It reminds that the sheep farm should strictly control the dosage according to the antimicrobial sensitive data in clinic.

110kV输电线路雷击故障分析及防雷改造研究

针对某地区110 kV的线路雷电跳闸事件,结合故障发生时的雷电定位信息、EMTP仿真结果以及电气几何模型,对该次接地故障进行分析。统计分析该线路走廊300 m近10年的雷电地闪空间分布、大于60 kA的危险雷电流分布及历史跳闸情况,提出在易受雷电侵害的#8~#10和#28~#35塔段应考虑加装线路避雷器防范雷电反击,并在全线整体考虑进行绕击耐雷水平校核和绝缘配合,避免雷电绕击后沿导线传播。

基于适配体吸附金纳米颗粒比色传感检测组胺

建立一种基于核酸适配体吸附金纳米颗粒(gold nanoparticles,AuNPs)比色传感方法特异性检测组胺的方法。利用组胺的双重作用,1)能与其适配体特异性识别,暴露AuNPs表面;2)多余组胺中的咪唑环结构能取代AuNPs表面的柠檬酸根离子,破坏AuNPs间的相互静电作用,导致聚集现象,进而引起从红到蓝的颜色变化,从而实现组胺的定量检测。利用紫外-可见分光度计考察AuNPs的吸光度变化,得出比色方法的检测限为8.89 nmol/L,线性范围为50 nmol/L~1.2μmol/L(R^(2)=0.999)。同时,利用手机成像样品,并利用Image J软件分析各样品的红(R)、绿(G)、蓝(B)各通道的值,选用G/R作为检测信号,得出RGB方法的检测限为24.91 nmol/L,线性范围为150 nmol/L~1.0μmol/L(R^(2)=0.997)。此外,该方法对组胺具有很好的选择性,两种信号输出方式在水样中的加标回收率分别为91.82%~102.27%、98.96%~102.89%;在鱼肉样品中的加标回收率分别为89.77%~108.92%、88.96%~109.82%。本方法简单、快速、便携,尤其RGB方法无需借助精密仪器,即能实现现场即时分析样品的需求,以期该方法能推广于高灵敏监测动物源性食品的新鲜度。

Investigation and Analysis on the Causes Affecting the Production of One Pig Farm in Southwest Region

To analyze the causes affecting production situation of one pig farm in southwest region,group leader,assistant and related staffs in the pig farm were queried,mating and delivery situation of sow and dead-culling situation ofpigletwere investigated.The results showed that(1) mating situation: mating 691 pigs,returning to love 42 pigs,abortion 4 pigs,mismatching rate was 7.59%.(2) Delivery situation: delivering 175 nests,total birth 2538,total piglet per fetus 14.5,average healthy piglet per fetus 10.12,invalid piglet rate was30.21%.Among them,mummy fetus,dead fetus,weak piglet and deformity accounted for 47.78%,35.64%,10.71% and 5.87% of invalid piglet.(3) Dead-culling situation: dead-culling rate in breeding process was 12.37%.Among them,diarrhea death wasthemain cause,accounting for 44.47%,followed by pressing,falling to the ground,disease,joint swelling,weakness and other causes,and they respectively accounted for 18.58%,13.36%,13.36%,8.56%,5.85% and 0.62%.

Tuning interaction strength between CeO_(2) and iridium to promote CO oxidation over Ir/TiO_(2)

The interaction between support and noble metal plays a crucial role in heterogeneous catalysis design.However,how to tune metal support interactions to optimize the activity still needs further exploration.CeO_(2) was introduced to promote CO oxidation ove r Ir/TiO_(2) by adjusting the interaction strength between iridium(Ir)and CeO_(2).The strong interaction between Ir and CeO_(2) blocks CO adsorption and causes low CO oxidation activity.However,introducing CeO_(2) on Ir/TiO_(2) produces localized interaction between Ir and CeO_(2),which can tune the surface electronic state of Ir,so a"volcano curve"relationship between CO oxidation activity and electronic state is built.Limited amount of CeO_(2) on Ir/TiO_(2)(Ir/Ce_(0.2)Ti)leads to CO complete oxidization at 22℃,and a new pathway for CO oxidation was explored.The study demonstrates that the utilization of tuning interaction strength between active metal and support is a potential method to increase the catalytic activity.

双烯烃橡胶复分解-加氢制备端羧基聚烯烃

采用烯烃复分解法,以双烯烃橡胶为原料,在Grubbs II代催化剂和链转移剂(马来酸)的作用下制得相应的端羧基聚二烯烃,通过对甲苯磺酰肼/三正丙胺试剂对其进一步加氢得到端羧基聚烯烃.主要研究了反应时间、反应温度、橡胶中双键/催化剂摩尔比、橡胶中双键/链转移剂摩尔比等因素对产物分子量及分子量分布的影响.通过核磁共振氢谱(1H-NMR)和碳谱(13C-NMR)、红外光谱(FTIR)、凝胶渗透色谱仪(GPC)、热重分析(TGA)和示差扫描量热分析(DSC)对产物的结构和性能进行了测试表征.结果表明,通过调整橡胶中双键/催化剂的摩尔比或橡胶中双键/链转移剂的摩尔比可以调控产物的分子量.另外,采用该方法制得的端羧基聚丁二烯具有较高的反式1,4-结构含量,与原料相比其顺式1,4-结构含量大幅下降,从而对产物的性能产生一定影响;而以异戊橡胶为原料时并没有观察到该现象.端羧基聚二烯烃经加氢反应后转变成端羧基聚烯烃,具有更好的热稳定性.该方法合成步骤简单,产物分子量可控,为功能材料的制备提供了新的可能.

长链脂肪族二元酸的合成及其在缩聚反应中的应用

长链脂肪族二元酸一般是指含有10个或以上碳原子的饱和直链二元酸,其两端带有羧基官能团,可用于合成香料、特种尼龙工程塑料、热熔胶、涂料、增塑剂、高级润滑油等众多化工产品;由于其链段中含有长烷烃链段,具有优于短链二元酸的性质,使得相应的合成材料具有优越的性能,因此广泛应用于化工、轻工、国防、汽车工业、工程材料等领域;同时,还可用于开发新的聚合物产品。长链脂肪族二元酸在自然界中不单独存在,目前工业上主要通过化学合成法和生物发酵法生产。本文主要对长链脂肪族二元酸的合成方法进行综述,包括传统有机合成、生物技术转化、烯烃复分解、异构化-氢氧羰基化及聚乙烯端基功能化等,并简要概述长链脂肪族二元酸在缩聚反应(聚酯和聚酰胺)中的应用。最后,对合成方法待解决的问题进行了总结,并对未来发展方向进行了展望。

水蒸汽驱动高聚物形状记忆效应的力学模拟

部分形状记忆高聚物在相对湿度较高的环境中会从其临时形状恢复到永久形状,这种效应被称之为水蒸汽驱动形状记忆效应.由于不需要升高温度就可实现形状恢复,水蒸汽驱动的形状记忆效应在多个领域都有着潜在的应用价值.本文拟建立一个热-力-化学多场耦合的理论模型来模拟非晶态高聚物的水蒸汽驱动形状记忆行为.该理论模型采用自由体积的概念来模拟玻璃态转变,采用Fick定律来模拟水蒸汽在高聚物基体中的扩散行为.相关有限元模拟结果表明,该模型能定性地描述文献中观察到的恢复温度、相对湿度以及溶剂分子扩散速度对形状恢复行为的影响,也能模拟复杂变形条件下水蒸汽驱动的形状记忆效应.

Tuning performance of Pd/Sn_(0.9)Ce_(0.1)O_2 catalyst for methane combustion by optimizing calcination temperature of support

A series of 0.2 wt% Pd/Sn_(0.9)Ce_(0.1)O_2 catalysts were prepared by impregnation method based on the presynthesis of Sn_(0.9)Ce_(0.1)O_2 support prepared by co-precipitation method, and then characterized by Brunauer–Emmett–Teller(BET), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Raman, CO chemical adsorption and hydrogen temperature-programmed reduction(H_2-TPR) techniques. The effect of calcination temperature of the composite oxide support on the catalytic performances of the Pd/Sn_(0.9)Ce_(0.1)O_2 catalyst for the CH_4 total oxidation was studied. It is found that the catalytic activity of the Pd/Sn_(0.9)Ce_(0.1)O_2 catalyst increases with the increase in calcination temperature of the Pd/Sn_(0.9)Ce_(0.1)O_2 support. The 0.2 wt% Pd/Sn_(0.9)Ce_(0.1)O_2/1100 catalyst(the Pd/Sn_(0.9)Ce_(0.1)O_2 support was calcined at 1100 ℃) exhibits the best reactive activity(T_(10)= 255 ℃). The excellent activity of the 0.2 wt% Pd/Sn_(0.9)Ce_(0.1)O_2/1100 catalyst should be attributed to the high reducibility of PdO, the excellent oxygen mobility of the support and the high content of active Pd^(2+) species on the Pd/Sn_(0.9)Ce_(0.1)O_2 catalyst.

Surface tuning of LaCoO_(3) perovskite by acid etching to enhance its catalytic performance

The stoichiometric LaCoO_(3) and nonstoichiometric LaCo_(1.2)O_(3) perovskite catalysts were prepared by citric acid sol-gel method,and then,LaCoO_(3) perovskite was etched with nitric acid.The structure,surface composition and reducibility of the catalyst were studied by X-ray diffraction(XRD),nitrogen desorption,transmission electron microscope(TEM),temperature program reduction of H_(2)(H_(2)-TPR) and X-ray photoelectron spectroscopy(XPS).It was found that nitric acid etching did not change the crystal structure and the overall morphology of the LaCoO_(3) catalyst,but it can cause the exposure of B-site Co metal to the surface of the catalyst.As a result,after acid etching,the reducibility of the LaCoO_(3) catalyst was improved,leading to the improvement in the catalytic activity of the LaCoO_(3) catalyst for CO oxidation and C_(3)H_(8) combustion.Moreover,the catalytic activity of the LaCoO_(3) catalyst after acid etching was higher than that of LaCo_(1.2)O_(3) and CoOx/LaCoO_(3) catalyst.

Solvent effects on oxygen atom transfer reaction between manganese(V)-oxo corrole and alkene

Pseudo-first order reaction rate constants of 5,10,15-tris（pentafluorophenyl）corrole Mn（V）-oxo （F_（15）CMn（V）-oxo）,5,15-bis（pentafluorophenyl）-10-（phenyl）corrole Mn（V）-oxo（F_（10）CMn（V）-oxo）,5,15- bis（phenyl）-10-（pentafluorophenyl）corrole Mn（V）-oxo（F_5CMn（V）-oxo） and 5,10,15-tris（phenyl）corrole Mn（V）-oxo（F_0CMn（V）-oxo） with a series of alkene substrates in different solvents were determined by UV-vis spectroscopy.The results indicated that the oxygen atom transfer pathway between Mn（V）-oxo corrole and alkene is solvent-dependent.

非晶态聚合物的速率相关韧脆转变模型

非晶态聚合物在玻璃化转变区的应力响应表现出明显的温度和速率依赖性.随着加载速率的增加,非晶态聚合物也表现出明显的拉伸破坏的韧脆转变.速率依赖性行为起源于固有的弛豫,从聚合物链段之间分子键的扰动到聚合物链的滑移.本文建立了一个本构模型,将键段动力学和链动力学分别纳入到键和聚合物网络的变形中.聚合物链的动态断裂也被纳入到描述聚合物损伤演化和最终失效的理论框架中.理论预测和实验结果的比较表明,该模型能够同时捕获观察到的速率相关特征,包括从玻璃态到橡胶态的转变、应变硬化和失效阈值.