献身演示实验室工作,提高物理课堂教学水平

作为演示实验室的教师 ,应结合教学内容 ,发挥积极性和创造精神 ,努力做好演示实验室的准备工作。同时 ,要利用现代化技术 ,不断研制和开发新的演示实验 ,本文介绍了几个新研制的实验。     

钯-高分子载体催化剂对糠醛加氢液相反应的研究

以弱碱性苯乙烯系阴离子交换树脂[D392,-NH₂,D382,-NHCH₃,D301R,-NH(CH₃)₂],强碱性苯乙烯系阴离子交换树脂[201×7DVB,-NH⁺(CH₃)₃]和弱碱性环氧系阴离子交换树脂(701,-NH₂)为载体制备了3种钯-高分子载体催化剂.考察了反应条件、高分子载体的种类、钯含量和催化剂用量对糠醛催化加氢生成四氢糠醇反应及催化性能的影响.在体积分数为50%的乙醇-水溶液和水中对糠醛常压液相加氢反应,钯-高分子载体(阴离子交换树脂D392,-NH₂,D382,-NHCH₃)催化剂均可使糠醛的加氢反应转化率达100%,生成四氢糠醇的选择性达98%以上,而用金属钯为催化剂的转化率达70%以上,选择性达97%以上.同时用XPS分析了高分子载体催化剂的结构与催化加氢反应性能的关系.     

Theoretical and experimental study on the conoscopic interference in uniaxial crystal (Ca0.28Ba0.72)x(Sr0.60Ba0.40)1‐xNb2O6

Conoscopic interference of polarized light for the white‐light and LPS‐7,5Volts direct current semiconductor laser (Green light) with wavelength at 532 nm in (Ca_0.28Ba_0.72)_x(Sr_0.60Ba_0.40)_1‐xNb₂O₆ crystals were observed with the beams transmitting along optical‐axes and deflection optical‐axes from 0 to 140°. Endo‐exo variation from looseness to tightness of conoscopic interference patterns were analyzed in theory. A hyperbolic black cross of interference patterns were observed as well as its formation process was proposed in this paper. Also, the inferences of the birefringence with different Ca²⁺‐doped were obtained in this investigation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Valence of elements in HgBa2Can-1CunO2n+2+d (n=1, 2, 3, 4)

Valence of elements in HgBa2Can-1CunO2n+2+d (n=1, 2, 3, 4) (both argon and oxygen annealed samples) were calculated. The result indicated for both argon and oxygen annealed samples, Hg had the lowest valence for the highest Tc sample. For fixed n, the valence of Cu in oxygen annealed samples was larger than that in argon annealed samples, indicating that oxygen annealed samples produce more carriers than argon annealed samples.     

N-四氢苯并噻唑亚胺Schiff碱的化学发光测定

新合成的噻唑类Schiff碱N-(2-四氢苯并噻唑)-2-羟基苯甲亚胺及类似化合物与Ce⁴⁺反应可产生微弱的化学发光,使用增敏剂奎宁可使发光显著增强.研究其发光反应动力学曲线、荧光光谱、化学发光光谱以及Schiff碱与Ce⁴⁺混合前后紫外可见吸收光谱的变化,确定了发生反应的官能团,讨论了发光反应的机理.考察了奎宁存在下Schiff碱与Ce₄₊化学发光反应条件及共存物质对发光强度的影响,建立了流动注射化学发光测定Schiff碱的方法.该法线性范围为2.0×10^-7～1.0×10^-4mol/L,检出限为8.0×10^-8mol/L,对2.0×10^-6mol/L噻唑类Schiff碱7次平行测定的相对标准偏差为2.4%.除Mn²⁺,Fe³⁺,Fe²⁺,Bi³⁺,Ti⁺外,大部分金属离子及500倍药物辅料淀粉不干扰噻唑类Schiff碱测定.与已有方法相比,具有灵敏、快速、简单、全自动等特点,成功地用于合成样品的分析。     

高碳高钢系高速钢的耐磨性研究

制备了不同成分的新型高碳高钢系高速钢,并与高铬铸铁对比考察了其耐磨性和磨损机理。结果表明：高碳高钡系高速钢的耐磨性明显优于高铬铸铁;其组织中的碳化物形态对耐磨性具有显著影响,其中具有细小及弥散分布的颗粒状ＭＣ型碳化物组织的试样的耐磨性最佳;其磨损机理为犁削和应力作用下碳化物的脆性碎裂及脱落。     

冷冻干燥对人类体液代谢组影响的NMR研究

样品前处理是代谢组分析的重要环节，而冷冻干燥是样品前处理过程中去除溶剂的重要方法，但冷冻干燥对代谢组分析结果的影响还有待进一步研究.本文以人类尿液和血清样本为研究对象，采用核磁共振（NMR）技术分析了冷冻干燥对这两种重要体液代谢组的影响，发现冷冻干燥会引起体液样本中部分有机羧酸和氨基酸含量的改变；而且，冷冻干燥对尿液和血清样品代谢组的影响不同，这可能与两种体液的生物基质差异有关.本研究结果表明，在代谢组学研究中要格外关注冷冻干燥对样品前处理及后续数据归一化所产生的影响.     

Triphenylphosphine-Functionalized Core-Cross-Linked Micelles and Nanogels with a Polycationic Outer Shell: Synthesis and Application in Rhodium-Catalyzed Biphasic Hydrogenations

Unimolecular amphiphilic nanoreactors with a poly(4-vinyl-N-methylpyridinium iodide) (P4VPMe⁺I⁻) polycationic outer shell and two different architectures (core-cross-linked micelles, CCM, and nanogels, NG), with narrow size distributions around 130–150 nm in diameter, were synthesized by RAFT polymerization from an R₀-4VPMe⁺I⁻₁₄₀-b-S₅₀-SC(S)SPr macroRAFT agent by either chain extension with a long (300 monomer units) hydrophobic polystyrene-based block followed by cross-linking with diethylene glycol dimethacrylate (DEGDMA) for the CCM particles, or by simultaneous chain extension and cross-linking for the NG particles. A core-anchored triphenylphosphine (TPP) ligand functionality was introduced by using 4-diphenylphosphinostyrene (DPPS) as a comonomer (5–20 % mol mol⁻¹) in the chain extension (for CCM) or chain extension/cross-linking (for NG) step. The products were directly obtained as stable colloidal dispersions in water (latexes). After loading with [RhCl(COD)]₂ to yield [RhCl(COD)(TPP@CCM)] or [RhCl(COD)(TPP@NG)], respectively, the polymers were used as polymeric nanoreactors in Rh-catalyzed aqueous biphasic hydrogenation of the model substrates styrene and 1-octene, either neat (for styrene) or in an organic solvent (toluene or 1-nonanol). All hydrogenations were rapid (TOF up to 300 h⁻¹) at 25 °C and 20 bar of H₂ pressure, the biphasic mixture rapidly decanted at the end of the reaction (<2 min), the Rh loss was negligible (<0.1 ppm in the recovered organic phase), and the catalyst phase could be recycled 10 times without significant loss of catalytic activity.     

Synthesis of porous Cu–Sn using freeze-drying process of CuO–SnO2/camphene slurries

Porous Cu–Sn with controlled pore characteristics was synthesized by a freeze-drying and sintering process. CuO and SnO₂ powders were selected as the source material, which are hydrogen-reduced to metallic Cu–Sn in the sintering stage. Camphene-based CuO–SnO₂ slurries were prepared by milling at 60 °C with a small amount of dispersant. Freezing of a slurry was done at ?40 °C with unidirectional control of the growth direction of the camphene. Pores were generated by sublimation of the camphene. The green bodies were sintered at 650 °C under a hydrogen atmosphere. The sintered bodies with Cu₃Sn, Cu₆Sn₅ and β-Sn phases showed macroscopic aligned pores with an average size of 200 μm. The internal wall of the macroscopic pores is also porous, and there are a number of many small pores in it. The formation of macroscopic and microscopic pores was discussed in terms of solidification behavior of the liquid with foreign particles.