耐水钛系催化剂的合成及其在聚对苯二甲酸丁二醇酯合成中的应用

以钛酸四丁酯、柠檬酸或乳酸和氢氧化钾为原料在水中合成了一系列α-羟基酸钛催化剂,¹³C NMR、HR-MS(ESI)和元素分析表征。结果表明：α-羟基酸钛催化剂主要含柠檬酸或乳酸的α-羟基和α-羧基与钛离子形成的五元螯合环三配体配合物。其中,采用柠檬酸与TBT在氢氧化钾参与条件下制得的CTK-312催化剂,能够合成特性粘度高达1.268 dL·g^-1的PBT。      

Boosting Photocatalytic Oxygen Evolution: Purposely Constructing Direct Z-Scheme Photoanode by Modulating the Interface Electric Field

Ti-Fe₂O₃ photoanode has received widespread attention in photoelectrochemical(PEC) water spilling because of its optimized oxidative and reductive capability of composites catalyst. However, its low efficiency could limit its development. Herein, in order to improve the efficiency of PEC water spilling, the all-solid-state direct Z-scheme Ti-ZnFe₂O₄/Ti-Fe₂O₃(TZFO/Ti-Fe₂O₃) nanorod arrays composited with the ideal energy band structure are synthesized by modulating the Fermi level of TZFO for PEC water splitting. The photophysical methods in this work, including the Kelvin probe measurement and transient photovoltage spectroscopy(TPV) measurement, are applied to explore the migration behavior of electric charges at the enhanced interface electric field. Finally, the Z-scheme charge transfer mechanism of TZFO/Ti-Fe₂O₃ photoanode is proved successfully. Benefiting from the desirable charge transfer at interface electric field, the TZFO/Ti-Fe₂O₃ exhibits the outstanding photocatalytic oxygen evolution reaction(OER) performance, and the photocurrent of 60TZFO/Ti-Fe₂O₃ photoanode reaches 2.16 mA/cm² at 1.23 V vs. reversible hydrogen electrode(RHE), which is three times higher than that of pure Ti-Fe₂O₃ photoanode. This work provides a facile approach of modulating interface electric field to optimize the Z-scheme charge-transfer process.     

Aerobic Oxidation of Alcohols to Aldehydes and Ketones with Recyclable Pd Catalysts on Cross-linked 1,10-Phenanthroline Polymers

A 1,10-phenanthroline based polymer named PPPhen(i.e., polymer from pyrene 1,10-phenanthrolin) was prepared by the Friedel-Crafts reaction of 1,10-phenanthroline and pyrene cross-linked with dimethoxymethane. The related Pd catalyst Pd@PPPhen was prepared by supporting Pd nanoparticles(NPs) on the PPPhen material. PPPhen and Pd@PPPhen were characterized by means of scanning electron microscopy(SEM), transmission electron microscopy, N₂ adsorption-desorption, Fourier-transform infrared and X-ray photoelectron spectroscopy analyses. The results showed that PPPhen polymer was highly porous and that the phenanthroline group can enhance the stability of the Pd nanoparticles. Pd@PPPhen also exhibited good catalytic activity in the aerobic oxidation of alcohols to aldehydes and ketones, and Pd@PPPhen was recyclable with durable activity and retentive structures.     

选矿产品矿物自动分析的光片制备

基于扫描电子显微镜的矿物自动分析仪(Quantitative Evaluation of Minerals by Scanning Electronic Microscopy)、MLA(Mineral Liberation Analyser)和AMICS(Advanced Mineral Identification and Characterization System)可用于测定选矿产品中目的矿物的粒度和单体解离度,为确定合理的磨矿细度以及优化选矿工艺流程提供依据。环氧树脂光片的制备是矿物自动识别和测量的最关键的一环,其代表性直接关系到后续数据测量的准确性和真实性。对于金属矿产品来说,由于选矿产品中矿物颗粒粗细不均、密度差异较大,在环氧树脂胶结固化过程中矿物颗粒会产生明显的分异作用并互相黏连,造成分析结果失真。实验证明,把样品与晶质石墨混均,然后加入环氧树脂以及固化剂搅拌混合倒入圆柱状模具进行冷镶嵌,待样品固化后再沿圆柱体的纵向进行切割,并对其切割面进行粗磨、细磨、精磨以及抛光,就可以制备出样品分散性好、分布均匀、表面光滑平整的具有代表性的环氧树脂光片。     

pH计检定仪期间核查方法

介绍pH计检定仪的4种期间核查方法:传递比较法、多台对比法、留样测量法、实验室间比对法。传递比较法能直接反应pH计检定仪的变化,适用于已建立pH计检定仪检定装置的单位;多台对比法与留样测量法方便、快捷,可操作性强,适合大多数单位进行pH计检定仪的期间核查;实验室间比对法对设备要求较低,但需要协调的单位较多,周期较长,费用较高,实用性差。     

基于光滑粒子流体动力学的滑油泵数值仿真

基于光滑粒子流体动力学方法,构建齿轮泵壳体及内部流体的粒子模型,对内啮合齿轮泵在不同工况下的流量特性进行数值模拟。首先设置了均匀分布的油泵出入口压强,计算得到的流量结果与试验结果吻合,且在中低转速下流量与转速呈线性关系;针对高转速下油泵流量降低的问题,通过适当减小周期模型内部的流体粒子数反映流量降低,获得了与试验值相吻合的连续转速流量的模拟结果;针对影响齿轮泵性能的间隙和空化现象,结合模型特点给出了相应的近似处理方法。通过以上研究,将SPH方法成功地应用于滑油泵问题的分析计算。     

综合性设计性实验的教学思路探讨

介绍了北京科技大学近年来面向低年级本科生开设综合性设计性实验的教学思路.在实验项目的设置上,根据实验室条件重点考虑可操作性;在实验内容方面重点考虑渐进性,让学生力所能及;在教学方式上强调引导,激发学生的研究兴趣.     

诺贝尔物理学奖与长度基准的历史沿革

从2005年诺贝尔物理学奖出发,考察了已往和长度基准有关的诺贝尔物理学奖,从物理学史的角度．探讨了长度基准的历史沿革及其意义．     

以橘子皮为碳源合成的CeO2@C及其对酸性染料去除性能

以Ce(NO₃)₃·6H₂O、橘子皮为原料,利用共沉积法制备氧化铈水合物与橘子皮混合物(CeO₂·x H₂O@OPP),通过在N₂中煅烧CeO₂·x H₂O@OPP获得CeO₂@C复合材料。利用FT-IR、X射线衍射、扫描电镜、拉曼光谱、UV-Vis、X射线光电子能谱、光电流测试方法对合成材料进行了表征。结果表明,CeO₂@C保留了较多的有机官能团,材料内具有较丰富的氧空穴及碳键,Ce、C、O元素均匀分布于材料内。光催化实验结果表明,在CeO₂中引入碳有利于光生电子与空穴分离,提高光电流强度及光催化效率,且CeO₂@C中碳含量对有机染料吸附及光催化效率影响较大。     

氮杂环丙烷化合物在直链淀粉柱上的拆分

在自制的直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)(ADMPC)手性固定相上,对2种氮杂环丙烷对映体进行了手性拆分研究.系统选用了不同种类及不同含量的醇改性剂,详细考察了样品的保留时间和立体选择性.