甲基丙烯酸甲酯-苯乙烯无规共聚物与聚偏氟乙烯共混体系的结晶行为和力学性能

本文研究了甲基丙烯酸甲酯-苯乙烯(MS)无规共聚物与聚偏氟乙烯(PVF_2)共混体系的结晶行为和力学性能。MS含量及MS中St的含量均对PVF_2的结晶行为有较大的影响,它显示出非晶材料向结晶材料转变过程中所特有的力学性质不连续现象。研究结果表明了PVF_2/MS共混物作为一种改性材料应用的可能性。     

InGaAs/GaAs应变量子阱的光谱研究

分别用光致发光谱（PL），光伏谱（PV）及时间分辨谱（TRPL）的方法，测量了应变InGaAs/GaAs单量子阱和多量子阱在不同温度下的光谱，发现单量子阱与多量子阱有不同的光学4性质。多量子阱PL谱发光峰和PV谱激子峰的强度与半高宽都比单量子阱的大，但单量子阱的半高宽随着温度的升高增大很快，这是由激子－声子耦合引起的，通过时间分辨谱研究发现了量子阱子能级之间的跃迁，多量子阱的发光寿命明显比单量子阱的长，我们利用形变势模型对量子阱的能带进行了计算，很好地解释了实验结果。     

高功率梯度折射率分别限制异质结构InGaAs/AlGaAs应变双量子阱激光器

采用金属有机化合物气相淀积（ Ｍ Ｏ Ｃ Ｖ Ｄ）方法成功地研制了具有两对梯度折射率（ Ｇ Ｒ Ｉ Ｎ）异质结结构的 Ｉｎ Ｇａ Ａｓ／ Ａｌ Ｇａ Ａｓ 应变双量子阱激光器。该激光器的波长为 ９７０～９８２ ｎｍ ,室温连续工作阈值电流密度为１４０ Ａ／ｃｍ ２, 工作在０．９ Ａ 时单面连续输出光功率为５２０ ｍ Ｗ , 工作在２．０ Ａ 时, 连续输出光功率为 １．４９ Ｗ , 最高功率可达 ２．４ Ｗ 。微分量子效率高达０．８３ Ｗ ／ Ａ。     

Strain‐Accelerated Formation of Chiral,Optically Active Buta‐1,3‐dienes

The formal [2+2] cycloaddition–retroelectrocyclization (CA–RE) reactions between tetracyanoethylene (TCNE) and strained, electron‐rich dibenzo‐fused cyclooctynes were studied. The effect of ring strain on the reaction kinetics was quantified, revealing that the rates of cycloaddition using strained, cyclic alkynes are up to 5500 times greater at 298 K than those of reactions using unstrained alkynes. Cyclobutene reaction intermediates, as well as buta‐1,3‐diene products, were isolated and their structures were studied crystallographically. Isolation of a rare example of a chiral buta‐1,3‐diene that is optically active and configurationally stable at room temperature is reported. Computational studies on the enantiomerization pathway of the buta‐1,3‐diene products showed that the eight‐membered ring inverts via a boat conformer in a ring‐flip mechanism. In agreement with computed values, experimentally measured activation barriers of racemization in these compounds were found to be up to 26 kcal mol^?1.     

辐照法制备PVAc/蒙脱土纳米复合材料及其表征

蒙脱土有机化后 ,片层结构间距离增大 ,对有机物的亲和性有所增强 .采用VAc单体渗入有机化蒙脱土层间 .经γ 射线辐照引发原位插层聚合 ,使蒙脱土片层结构发生剥离 ,形成无机 有机纳米复合材料 .并用X衍射、红外光谱、扫描电镜以及透射电镜等现代测试手段对复合材料进行了表征     

Modeling the relationship between hydrogen content and mechanical property of Ti600 alloy by using ANFIS

An adaptive network based fuzzy inference system (ANFIS) was used to predict the tensile strength of Ti600 alloy after hydrogenation. In this approach, the whole procedure of structure identification and parameter optimization was carried out automatically and efficiently. Two major influence factors were considered as input variables including hydrogenation temperature ranging of 600–750 °C and hydrogen content ranging of 0–0.502 wt.%, two different membership functions, triangular and Gaussian, were employed as fuzzy subset to compare the model accuracy. After the training and testing process, the predicted values were compared with experimental result and multiple linear regression values. It is found that the ANFIS predicted values with Gaussian and Triangular membership function were in good agreement with the experimental results with relative error of 2.69% and 2.77%, which has a equal accuracy but higher than multiple linear regression method with the error of 16.74%. Such modeling approach for the hydrogenation of titanium alloy can be highly beneficial since it offers the possibility of identifying promising processing parameters without the necessity for extensive experimental test cycles.     

Catalytic cyclopropanation of hexa-1,3,5-triene with diazomethane as a simple synthesis of high-energy tercyclopropane

A simple method for a preparing of tercyclopropane or 1,2-dicyclopropylethene by the catalytic cyclo-propanation of hexa-1,3,5-triene with diazomethane has been developed. Thermochemical characteristics for tercyclopropane show that it may be a candidate to replace syntin as a propellant for spacecraft engines.     

封装材料对二代高温超导带材稳态过电流能力与拉伸性能影响的实验研究

随着二代高温超导带材从实验室走出，二代高温超导带材进入商业化大规模生产和应用阶段.针对不同的应用场景对热学、电学和力学性能的特殊要求，需要对二代高温超导带材匹配不同的后处理工艺，例如分切、镀铜以及封装等.为了解决现有常用封装材料(紫铜和不锈钢)各自的短板，本文采用铜合金材料封装，详细对比了铜银合金与黄铜与现有常用封装材料在超导带材稳态过电流能力和轴向拉伸性能的差异.发现铜银合金封装的二代高温超导带材的综合性能优于紫铜封装和不锈钢封装的二代高温超导带材.本文的研究也为实际应用中二代高温超导带材的选型提供参考.     

Tensile property of cord reinforced rubber composites laminate double lap jointEI北大核心CSCD

According to the structural connection form of cord reinforced rubber composite，structural test samples with different lapping process parameters were designed and prepared. The dynamic and static tensile properties were studied by using two-dimensional digital image technology. The test results were as follows：The stiffness and tensile strength of double lap composites joints increased as the strain rate increasing，while the elongation at break unchanged. Compared with the no-lap samples，the tensile strength of the double lap composites sample was reduced by nearly 50%，and with the increase of the lap width，the elongation at break gradually decreased. The samples with lap width of 65 mm decreased by 24% compared with the no-lap ones. Compared with the elastic modulus of stage II，the elastic modulus of stage III increased significantly，that of the no-lap samples increased by 3 times，that of the lap samples were doubled，and the amplification of elastic modulus decreased with the increase of strain rate. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Passivation techniques for InAs/GaSb strained layer superlattice detectors

InAs/(In,Ga)Sb Strained Layer Superlattices (SLSs) have made significant progress since they were first proposed as an infrared (IR) sensing material more than three decades ago. The basic material properties of SLS provide a prospective benefit in the realization of IR imagers with suppressed interband tunneling and Auger recombination processes, as well as high quantum efficiency and responsivity. With scaling of single pixel dimensions, the performance of focal plane arrays is strongly dependent on surface effects due to the large pixels’ surface/volume ratio. This article discusses the cause of surface leakage currents and various approaches of their reduction including dielectric passivation, passivation with organic materials (polyimide or various photoresists), passivation by overgrowth of wider bandgap material, and chalcogenide passivation. Performance of SLS detectors passivated by different techniques and operating in various regions of infrared spectrum has been compared.