易轴取向对硬磁/软磁多层膜磁性能的影响

通过微磁学方法,系统计算了硬磁/软磁多层膜（Nd2Fe14B/-Fe多层膜）在晶轴和外场存在夹角情况下的磁矩空间分布、磁滞回线和磁能积.计算表明,在膜面内易轴的偏角对磁性多层膜的磁化反转过程以及剩磁和钉扎场的影响较大.与=0°的情况相比,偏角不为0°时,体系没有明显的成核点.只有在剩磁状态（H=0）时,磁性多层膜内部的磁矩才会出现一致的取向（≡）,随着外场的减小,软磁相内部磁矩快速偏转,并且通过界面处的交换耦合作用带动硬磁相内部磁矩的偏转.当软磁相厚度较小时,钉扎场随着的增大先减小后增大,在等于30o附近出现一个低谷;当软磁相厚度较大时,钉扎场随着的增大而单调增大.体系的剩磁和矫顽力随着的增加都呈现出减小的趋势,导致磁能积随的增加而急剧减小,这在一定程度上解释了材料最大磁能积的实验值和理论值之间的巨大差距.     

High Efficient Extraction of Phthalates in Aquatic Products by a Modified QuEChERS Method

A simple, environmentally friendly and high efficient extraction method was proposed for the determination of five phthalates in aquatic products by gas chromatography combined with mass spectrometry detector (GC-MS). When this method was adopted, samples were pretreated by modified QuEChERS(quick, easy, cheap, effective, rugged and safe) method. An environmentally friendly extractant(ethanol aqueous solution) replaced toxic acetonitrile for extracting phthalates in the protein-matrix samples. Fluorescence quenching spectra of bovine serum albumin(BSA) with phthalates show that there was a high-affinity interaction between phthalate and protein, decreasing the extraction efficiency of phthalates from fish samples. However, in the 80%(volume fraction, φ) ethanol aqueous solution, a slow but full protein denaturation takes place, which would cause the unfolding of protein and the release of phthalates. Meanwhile, the fat-soluble impurities are extracted less in φ(ethanol) 80% aqueous solution than in either φ(ethanol) 100% or hydrophobic solvents in the liquid-liquid extraction procedure. Therefore the purification steps were greatly simplified. Overall recoveries were 81.77%―90.5% with limits of detection between 2.53 and 9.61 μg/L, and relative standard deviation values at 1.15%―4.85%. The proposed approach was satisfactorily applied to the determination of phthalates in real aquatic products, such as fish, shrimp and oyster.     

山西省泥石流地质灾害发育特征与防治对策

山西省泥石流地质灾害危害呈逐年上升趋势。据不完全统计,全省已发现泥石流及其隐患点544余处,因灾死亡352人,造成的直接经济损失4.72亿元。泥石流灾害分布具有较明显的地域特征。东部太行山区降水量较为充沛,为稀性水石流高易发区;中部盆地及各大矿区主要发育泥石流、泥渣流;西部吕梁山区和晋西黄土高原主要发育粘性泥石流、泥流,规模多为小～中型。通过总结山西泥石流灾害发育特征,为泥石流灾害预警和防灾减灾提供技术支撑。     

PA6／EHDPET共混纤维的相形态结构

合成了一系列易水解聚酯(EHDPET),并对其[η],t_(g),t_(cc),t_(mc)及 t_m 等热性能和流变性能进行了表征.用扫描电镜(SEM)观察了 PA6/EHDPET 共混纤维的相形态结构,其结果表明:(1)当共混组分的熔体粘度比(η_m(PA6)/η_m(EHDPET))不变时,改变共混体积组成比(V(PA6)/V(EHDPET)),所得共混纤维可具有 PA6为岛相或为海相的形态结构;而当共混组成比不变时,改变共混组分的熔体粘度比,也可得到 PA6为岛相或为海相的共混纤维.(2)当共混两组分的熔体粘度比大于9.25时,即便体积组成比高达70/30,PA6亦可构成岛相.所得共混纤维可用于制备超极细纤维或多孔中空纤维.     

试论孙中山"知难行易"思想的现代启示

孙中山“知难行易”学说的核心是强调人们要敢于实践,乐于实践,在实践中求知。该学说不仅具有超越传统狭隘的“知行观”的思想价值,而且洋溢着的自强不息的奋斗精神和勇于探索的创新精神,对我国当今的现代化建设具有重要的启迪意义。     

Substituting AI for Fe in Pr（AlxFe1-x）1.9 alloys： Effects on magnetic and magnetostrictive properties

The magnetostrictive effects of substituting A1 for Fe in Pr（AlxFe1-x）1.9 （x = 0.0, 0.02, 0.05, 0.10） alloys between 5 K and 300 K were investigated. The substitution decreases the Curie temperature and the value of λ111. Fortunately, the substitution slightly increases the magnetostriction in a low magnetic field, which imbues these materials with potential advantages for applications. Rotation of the easy magnetization direction （EMD） from [ 111 ] to [ 100] in the Pr（A10.02Fe0.98）1.9 alloy as temperature decreases was detected by step scanned XRD reflections.     

Tuning catalyst solubility in CO2 by changing molar volume

Abstract

Poor-solvating property of supercritical carbon dioxide (scCO₂) has been a great challenge, which limits the use of CO₂ as a common “green” solvent. The present report describes that by increasing molar volume (v) and lowering the melting temperature, which lowers cohesive energy density or solubility parameter (δ), it is possible to increase the solubility of metal-based catalysts in scCO₂ without using costly fluorinated or tailor-made CO₂-philic modifications. We have studied various chlorodistannoxanes (1) and Cu–β-diketonates (2) to support our views. The study of bio-diesel production and transesterification of hindered esters using 1 in scCO₂ shows a 2–8-folds rate enhancement coupled with an easier catalyst and product separation than that in organic solvents. The methodology, which works at least within the range of Van der Waals sphere of interactions, can be useful to solubilizing the molecules in scCO₂ and carries great opportunity in catalysis as well as in separation science.     

Novel approaches in analysis of Fusarium mycotoxins in cereals employing ultra performance liquid chromatography coupled with high resolution mass spectrometry

Rapid, simple and cost-effective analytical methods with performance characteristics matching regulatory requirements are needed for effective control of occurrence of Fusarium toxins in cereals and cereal-based products to which they might be transferred during processing. Within this study, two alternative approaches enabling retrospective data analysis and identification of unknown signals in sample extracts have been implemented and validated for determination of 11 major Fusarium toxins. In both cases, ultra-high performance liquid chromatography (U-HPLC) coupled with high resolution mass spectrometry (HR MS) was employed. ¹³C isotopically labeled surrogates as well as matrix-matched standards were employed for quantification. As far as time of flight mass analyzer (TOF-MS) was a detection tool, the use of modified QuEChERS (quick easy cheap effective rugged and safe) sample preparation procedure, widely employed in multi-pesticides residue analysis, was shown as an optimal approach to obtain low detection limits. The second challenging alternative, enabling direct analysis of crude extract, was the use of mass analyzer based on Orbitrap technology. In addition to demonstration of full compliance of the new methods with Commission Regulation (EC) No. 401/2006, also their potential to be used for confirmatory purposes according to Commission Decision 2002/657/EC has been critically assessed.     

材料因素对学习难易度判断及其准确性影响的实验研究

通过两个实验分别考察了材料因素(词频与关联性)对学习难易度判断及其准确性的影响。结果发现:材料因素对学习难易度判断的具有较为稳定的影响,研究支持"加工容易性启发"假说;词频和关联性对学习难易度判断准确性均具有显著影响,但二者对学习难易度判断准确性的影响方式不同,词频仅引发编码流畅性,关联性不仅可以引发编码流畅性,同时也引发提取流畅性;不同关联性材料的EOL判断准确性显著高于不同词频材料的EOL判断准确性。     

Influence of Tester Geometry,Speed and Procedure on the Results from a Ring Shear Tester

Automated ring shear testers have gained widespread acceptance in the chemical industry. In this paper, comparative measurements with different shear testers are described and possible factors influencing the measurement of flowability, are discussed. The measurement results presented show a dependency on the bulk solid investigated. No significant influence of the shear tester was measured for easy flowing bulk solids. An influence of the shear tester is observed for poor flowing, compressible bulk solids. Experiments have shown that test procedure and shear cell design (tester geometry) affect the measurements considerably.