La2O3-Mo5Si3/MoSi2复合材料的高温氧化行为

研究了0．8％La2O3-MosSi3／MoSi2复合材料在1200℃空气中的高温氧化行为。结果表明：0．8％稀土和MoSi3的加入，使材料的抗氧化性能降低。MosSi3含量越高，材料的抗氧化性能越差。当MosSi3含量低于30％时，在氧化初始阶段，质量变化呈直线下降，随着氧化的进行，氧化逐渐增重，材料表面形成较致密的SiO2阻止了材料的进一步氧化，使得氧化增重较小。而0．8％La2O3-40％Mo5Si3／MoSi2复合材料却出现了“粉化”现象。0．8％La2O3．MosSi3／MoSi2复合材料抗氧化性能的降低，归因于Mo5Si3差的抗氧化性和材料致密度的降低；另外，稀土和Mo5Si3的加入，细化了材料的晶粒，使晶界面积增加，加速了氧在晶界中的扩散，促进了材料的氧化。     

稀土对MoSi2力学性能和抗氧化性能的影响

采用自蔓延和真空烧结方法制备了掺杂0．9％La2O3的MoSi2基复合材料，利用热重分析法，SEM和X射线考察了La2O3颗粒对MoSi2力学性能、抗氧化特性以及循环氧化后力学性能的影响。结果表明，与纯MoSi2相比，RE／MoSi2材料的弯曲强度和断裂韧性分别提高了46％和78％；稀土对MoSi2材料的强韧化机制主要是细晶强化、弥散强化和细晶韧化。RE／MoSi2的氧化增重是纯MoSi2的2．5倍，稀土使MoSiz材料的抗氧化性能降低。由于纯MoSi2材料氧化后的晶粒长大，其抗弯强度比氧化前降低了17％。稀土对MoSi2氧化时的晶粒长大倾向有抑制作用，使得RE／MoSi2材料的抗弯强度基本不变。     

铜(Ⅰ)配合物[Cu(C8H4O2F3S)(PPh3)2]合成、性质、晶体结构及反应机理的探讨

Reaction of copper powder with 2-thenoyltrifluoroacetone and PPh₃ yielded the complex [Cu(C₈H₄O₂F₃S)(PPh₃)₂], which have been characterized by elemental analysis and IR spectra. The crystal is monoclinic, space group P2₁/n , a=1.0584(1), b=1.6738(1), c=2.2728(9) nm; β =94.22(2); V =4.0152 nm 3; Z=4; D_c=1.299 g·cm^-3; R=0.048, R_W=0.054. Copper (Ⅰ) ion is coordinated by two O and two P atoms forming distorted tetrahedron.     

钙钛矿型La_((1 x)/2)Sr_((1-x)/2)Co_(1-x)Cu_xO_3催化CO氧化活性与表征

研究了钙钛矿型LaSrCoCu_xO_3催化剂对CO氧化反应的催化活性及其表面氧的催化作用．结果表明，x＝0．4的催化剂对CO氧化具有最高催化活性，常压及本实验条件下CO完全氧化的最低温度为168℃；催化剂均为氧缺陷化合物，吸附于表面晶格氧缺陷上的吸附氧是CO氧化反应的活性氧物种；并发现催化剂中存在有非常价态的C04 ，认为CO氧化反应是通过吸附氧调变Co3 和Co4 价态而进行．     

A study of PBT/PC blends by modulated DSC and conventional DSC

Two poly(butylene terephthalate)/polycarbonate (PBT/PC) blends with different formulations were analyzed by modulated DSC (MDSC) and conventional DSC to determine differences in crystallization behavior. A significant difference (30°C in cold crystallization temperature) between the two samples was detectable by MDSC while no significant difference was seen by conventional DSC. That indicatesthe total heat flow from MDSC is not always equivalent to the heat flow from conventional DSC as we have assumed or seen before. The reason has not been fully understood, but may be related to unusual nucleation and crystallization induced by modulation. Alternative conventional DSC methods were developed and compared to the MDSC results.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayThe authors like to thank Drs. Bernhard Wunderlich and Robert Gallucci for helpful discussion, David Shaker and Mary Parsonage for some DSC experiments. Technical support from TA Instruments is also greatly appreciated.     

微波辐照下无皂阳离子聚(St-MMA)高分子纳米粒子的制备和表征

讨论了微波辐照下 ,以丙酮 水为分散介质 ,利用阳离子型自由基引发剂偶氮二异丁基脒盐酸盐(AIBA)引发苯乙烯 (St)和甲基丙烯酸甲酯 (MMA)共聚 ,合成出表面带正电荷的P(St MMA)共聚物纳米粒子 ,考察了丙酮用量、单体和引发剂浓度对纳米粒子粒径、粒径分布和乳液稳定性的影响 .结果表明 ,丙酮 水的体积比由 0增加到 1 2 6∶1时 ,粒子的平均水化半径从 12 2 2 1nm降低到 2 4 6 8nm ,粒径分布变宽 ,乳液抗电解质稳定性逐渐增强 ;增加引发剂和共聚单体MMA的浓度 ,粒子的水化半径逐渐减小 ,粒径分散系数增大 .     

2,5—双（4—羟基苯亚甲基）环戊酮中双电荷离子存在的串联质谱证据

应用串联质谱的碰撞诱导解离和联动扫描技术，研究了２，５－双（４－羟基苯亚甲基）环戊酮的质谱解离特征，提供了双电荷离子存在的实验证据。进一步对双电荷离子（ｍ／ｚ１４６）的碰撞诱导解离碎裂进行了讨论。     

Room‐Temperature Solution‐Processed PbS Quantum Dot Solar Cells

Colloidal quantum dots (CQDs) are attractive absorber materials for high‐efficiency photovoltaics because of their facile solution processing, bandgap tunability due to quantum confinement effect, and multi‐exciton generation. To date, all published performance records for PbS CQDs solar cells have been based on the conventional hot‐injection synthesis method. This method usually requires relatively strict conditions such as high temperature and the utility of expensive source material (pyrophoric bis(trimethylsilyl) sulfide (TMS‐S)), limiting the potential for large‐scale and low‐cost synthesis of PbS CQDs. Here we report a facile room‐temperature synthetic method to produce high‐quality PbS CQDs through inexpensive ionic source materials including Pb(NO₃)₂ and Na₂S in the presence of triethanolamine (TEA) as the stabilizing ligand. The PbS CQDs were successfully prepared with an average particle size of about 5 nm. Solar cells based on the as‐synthesized PbS CQDs show a preliminary power conversion efficiency of 1.82%. This room‐temperature and low‐cost synthesis of PbS CQDs will further benefit the development of solution‐processed CQD solar cells.     

Transition state modeling and catalyst design for hydrogen bond-stabilized enolate formation

[reaction: see text] A catalyst for enolate formation was designed that incorporates an amine base along with a thiourea to bind to the oxygen atom of the substrate and enolate through hydrogen bonding. A computational model of the transition state was developed in which the thiourea (modeled initially as a urea) and amine were separate molecules. This model and models incorporating one or two methanol molecules in place of the urea showed an out-of-plane hydrogen bond, apparently to the carbonyl pi-bond, in addition to an in-plane hydrogen bond to an unshared electron pair. In contrast, optimized complexes of the ketone and the fully formed enolate showed only in-plane hydrogen bonding. The transition state model with the urea and amine was used to define a database search with the computer program CAVEAT to identify structures suitable for linking the amine and urea/thiourea moieties in the transition state. On the basis of a group of structures identified from this search, a flexible but conformationally biased linker was designed to connect the two catalytic moieties. The molecule having the amine and thiourea moieties connected by this linker was synthesized and was shown to catalyze proton exchange between methanol and deuterated acetone. The catalyst was about 5-fold more efficient than the amine and thiourea as separate molecules and relative to a similar but less conformationally biased catalyst.     

热敏电阻温度计的设计与制作

本文介绍了设计性实验“热敏电阻的设计与制作”的实施情况。说明了只要选题合适、要求恰当,设计性实验不仅可行,而且对物理实验训练的总结提高十分有效。