Effects of the laser surface treatment on the mechanical properties of CuZr-based bulk metallic glasses

Surfaces of three types of CuZr-based bulk metallic glasses (BMGs) were modified by laser surface treatment (LST), and the influence of the treatment on structure and mechanical properties of these alloys was investigated. The phase structure of as-cast and laser-treated samples was characterized by XRD and the morphology of the alloys after fracture was examined by SEM. The compressive plasticity of treated Cu47.5Zr47.5Al5 and Cu46.5Zr47.5Al5Co1 BMGs can be improved from 0.5% to 2.0% and from 1.2% to 5.7% respectively compared with the as-cast ones, while (Cu0.55Zr0.40Al0.05)99Er1 BMG shows insignificant change of plasticity. The improvement in plasticity is attributed to induced crystallization of B2 CuZr phase in the treated surface zone of selected metallic glasses.     

Superconvergence of a two‐grid method for fourth‐order dispersive‐dissipative wave equations

In this paper, the superconvergence analysis of a two‐grid method (TGM) with low‐order finite elements is presented for the fourth‐order dispersive‐dissipative wave equations for a second order fully discrete scheme. The superclose estimates in the H¹‐norm on the two grids are obtained by the combination technique of the interpolation and Ritz projection. Then, with the help of the interpolated postprocessing technique, the global superconvergence properties are deduced. Finally, numerical results are provided to show the performance of the proposed TGM for conforming bilinear element and nonconforming element, respectively. It shows that the TGM is an effective method to the problem considered of our paper compared with the traditional Galerkin finite element method (FEM).     

A conjugated alkyne functional bicyclic polybenzoxazine with superior heat resistance

A difunctional benzoxazine (coPh‐apa) with a conjugated alkyne group is synthesized by the oxidative coupling reaction from a monocycle‐benzoxazine (Ph‐apa) containing an alkyne group. A model compound, 1,4‐diphenylbutadiyne (coPa), is used to study the curing reaction process of coPh‐apa by DSC, Fourier transform infrared spectroscopy, and ¹³C NMR, and the results suggest that the conjugated alkyne groups are involved in the crosslinking reaction via the trimerization reaction of the conjugated alkynyl groups and the Diels–Alder reaction. Furthermore, thermal properties of the polybenzoxazine are studied by dynamic thermomechanical analysis and thermogravimetric analysis. A glass‐transition temperature (T_gs) of as high as 412 °C and a char yield of 75.6% at 800 °C under nitrogen are obtained with the aid of the conjugated alkyne groups. Its excellent heat resistance dominates most thermosetting resins and will serve for heat shields. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1587–1592     

基于虚拟中心电流法的 HL-2M快控电源数学模型

针对中国环流器2号M(HL-2M)装置中用于核聚变物理实验等离子体的垂直不稳定性控制的快控电源拓扑结构，充分考虑线圈的自感与互感对输出的影响，构建出数学模型，首次提出并运用虚拟中心电流法，使得控制算法更加简单，采用多输入多输出的控制方法，利用2个参量控制3个变量。本文基于基本供电方案得到多线圈耦合电压，基于快控电源拓扑推导出快控电源电路方程，再将其合并得到最终的线圈电压数学模型，最后进行仿真验证。结果表明数学模型搭建正确，为今后进行进一步计算提供了坚实的基础。     

Nucleophilic substitution of ferrocenyl alcohols catalyzed by bismuth(III) in aqueous medium at room temperature

A nucleophilic substitution reaction of an α‐ferrocenyl alcohol with various amines, indoles and thiols was successfully developed by using a catalytic amount of Bi(NO₃)₃.5H₂O at room temperature without the aid of phase transfer catalyst. The reactions proceeded in aqueous media, leading to the formation of new C=C, C=N and C=S bonds bearing ferrocenyl substituent with high efficiency. Copyright © 2012 John Wiley & Sons, Ltd.     

Combined prostate diffusion tensor imaging and dynamic contrast enhanced MRI at 3T — quantitative correlation with biopsy

The purpose of this work was to compare diagnostic accuracy of Diffusion Tensor Imaging (DTI), dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) and their combination in diagnosing prostate cancer. Twenty-five patients with clinical suspicion of prostate cancer underwent MRI, prior to transrectal ultrasound-guided biopsies. MRI data were correlated to biopsy results. Logistic regression models were constructed for the DTI parameters, DCE MRI parameters, and their combination. The areas under the receiver operator characteristic curves (AUC) were compared between the models. The nonparametric Wilcoxon signed rank test was used for statistical analysis. The sensitivity and specificity values were respectively 81% (74–87%) and 85% (79–90%) for DTI and 63% (55–70%) and 90% (85–94%) for DCE. The combination “DTI or DCE MRI” had 100% (97–100%) sensitivity and 77% (69–83%) specificity, while “DTI and DCE MRI” had 44% (37–52%) sensitivity and 98% (94–100%) specificity. The AUC for DTI+DCE parameters was significantly higher than that for either DTI (0.96 vs. 0.92, P=.0143) or DCE MRI parameters (0.96 vs. 0.87, P=.00187) alone. In conclusion, the combination of DTI and DCE MRI has significantly better accuracy in prostate cancer diagnosis than either technique alone.     

Ultra-lightweight cellulose foam material: preparation and properties

Ultra-lightweight cellulose foams were prepared by regeneration of sodium dodecyl sulfate (SDS)/cellulose/NaOH/urea blend solution via mechanical agitation and then freeze-drying. The morphology and properties of the blend solutions and foams were investigated via optical microscope, rheometer, BET and SEM. As a result, it was found that the inclusion complex structure between cellulose macromolecules and the solvent molecules was not destroyed. Moreover, the bubbles were about 20–50 μm in the solutions and larger (>100 μm) in the foams. Not only the micropores (bubbles) but also the nanopores could be observed in the wet and dried foams. The cellulose foams possessed ultra-low density of about 30 mg/cm³ and high specific surface area. The result of X-ray diffraction and Fourier transform infrared spectroscopy indicated that the cellulose foams were transited from cellulose I to cellulose II after dissolution and gelation. Bubbles inside the wet foams weakened the mechanical properties, but inversely increased the mechanical properties in the dried foams. Typical “J”-shaped curves were observed during the mechanical test, which revealed good compressive strength of dried foams. In this work, cellulose foams with ultra-lightweight and good mechanical properties were obtained, which exhibited great potentials for further development and comprehensive utilization of cellulose.     

Characterizing affinity epitopes between prion protein and β-amyloid using an epitope mapping immunoassay

Cellular prion protein, a membrane protein, is expressed in all mammals. Prion protein is also found in human blood as an anchorless protein, and this protein form is one of the many potential sources of misfolded prion protein replication during transmission. Many studies have suggested that β-amyloid_1–42 oligomer causes neurotoxicity associated with Alzheimer''s disease, which is mediated by the prion protein that acts as a receptor and regulates the hippocampal potentiation. The prevention of the binding of these proteins has been proposed as a possible preventative treatment for Alzheimer''s disease; therefore, a greater understanding of the binding hot-spots between the two molecules is necessary. In this study, the epitope mapping immunoassay was employed to characterize binding epitopes within the prion protein and complementary epitopes in β-amyloid. Residues 23–39 and 93–119 in the prion protein were involved in binding to β-amyloid_1–40 and _1–42, and monomers of this protein interacted with prion protein residues 93–113 and 123–166. Furthermore, β-amyloid antibodies against the C-terminus detected bound β-amyloid_1–42 at residues 23–40, 104–122 and 159–175. β-Amyloid epitopes necessary for the interaction with prion protein were not determined. In conclusion, charged clusters and hydrophobic regions of the prion protein were involved in binding to β-amyloid_1–40 and _1–42. The 3D structure appears to be necessary for β-amyloid to interact with prion protein. In the future, these binding sites may be utilized for 3D structure modeling, as well as for the pharmaceutical intervention of Alzheimer''s disease.     

4-(2-(4-咪唑)苯乙烯基)吡啶和三种芳香二羧酸的Cd(Ⅱ)配位聚合物的合成、结构及荧光性质

以4-（2-（4-咪唑）苯乙烯基）吡啶（ISPE）为配体,分别与间苯二甲酸（1,3-H₂BDC）、4,4′-联苯二甲酸（4,4′-H₂BPDC）和4,4′-二苯乙烯二甲酸（4,4′-H₂STDC）及过渡金属盐Cd（NO₃）₂·4H₂O通过溶剂热自组装形成了3种配位聚合物晶体{[Cd₂（ISPE）₂（1,3-BDC）₂]·DMF}_n （1）、[Cd（ISPE）（4,4′-BPDC）]_n （2）和[Cd（ISPE）₂（4,4′-STDC）（H₂O）₂]_n （3）。并用单晶X射线衍射、PXRD、红外光谱、元素分析、热重等对其进行了表征。单晶解析结果表明：配位聚合物1是二维层状网格结构,配位聚合物2是一个六重穿插的类金刚烷三维网格结构,配位聚合物3是由一维网格结构通过氢键和分子间作用力堆积形成的三维网格结构。另外还研究了它们的室温固态荧光性能。