酸溶-碱提取-硫氰酸盐分光光度法测定岩石矿物中的钼含量

<正>钼在地壳中的质量分数约为3μg·g~(-1),自然界中已知的含钼矿物约有30余种~([1]),目前岩石矿物中钼的测定方法主要有重量法~([2])、容量法~([3])、分光光度法~([4-6])、原子吸收光谱法~([7-9])、电感耦合等离子体质谱法~([10-12])和电感耦合等离子体原子发射光谱法~([13-15])等。重量法和容量法操作繁琐,仅适用于钼     

岩石压剪断裂过程中的超声波波谱特性研究

岩石破裂过程中的声发射特性不仅与岩石种类有关 ,而且与受到的载荷和破裂进展密切相关 ,岩石受载时的声发射波谱中含有大量与微断裂有关的信息。本文通过岩石压剪加载时峰值前的声发射波谱特性分析 ,探讨了岩石压剪时的微断裂机理 ,揭示了岩石在压剪加载不同阶段的波谱特性与岩石初始非线性、线性响应和临界裂纹扩展之间的相关关系。实验结果表明 ,声发射波谱参数的变化对岩石微断裂进展的响应比载荷本身更为敏感。这一结论为岩石边坡稳定性分析 ,岩爆预测和采矿工程的安全性评估提供了十分有意义的实验依据。     

Thermal Rate Constants of the N（^4S）＋O2（X^3∑g^-） → NO（X^2Ⅱ） ＋O（^3P） Reaction on the ^2A′ Potential Energy Surface

A quasiclassical trajectory study with the sixth-order explicit symplectic algorithm for the N（^4S）＋O2（X^3∑g^-） → NO（X^2Ⅱ） ＋O（^3P） reaction has been reported by employing a new ground potential energy surface. We have discussed the influence of the relative translational energy, the vibrational and rotational levels of O2 molecules on the total reaction cross section. Thermal rate constants at temperatures 300, 600, and 1000 K determined in this work for the reaction are 4.4 × 10^7, 1.8 × 10^10, and 3.1 × 10^11 cm^3mol^-1s^-1, respectively. It is found that they are in better agreement with the experimental data than previous theoretical values.     

InAs/GaAs自组织量子点的DLTS谱

将DLTS用于对InAs/GaAsQD结构样品的测量,测定了QD能级发射载流子的热激活能;获得了QD能级俘获电子过程伴随有多声子发射(MPE)、QD能级存在一定程度的展宽、以及在某些特定的生长条件下,存在亚稳生长构形的实验证据.结果表明:DLTS在QD体系的研究中有其特有的功能     

纳米CeO2的制备及其在PMMA中的分散

制备得到一Ce-三乙醇胺(TEA)配合物,以该配合物作为制备纳米CeO2的前驱体.将甲基丙烯酸甲酯(MMA)分散于配合物水溶液中,然后在同一反应器中依次进行水解、乳液聚合反应,得到纳米CeO2分散于聚甲基丙烯酸甲酯(PMMA)基质中的复合物粉末.分别运用XRD,TEM,TGA和DSC对复合物进行了表征.结果表明,纳米CeO2粒径为3～5nm,其均匀分散于聚合物基质中且单分散性良好.聚合物的热稳定性和玻璃化温度得到提高.     

纳米硒化镉溶胶的制备

在胶束微环境下，研究了影响纳米硒化镉溶胶粒径的因素．反应物浓度(表面活性剂、还原剂)、温度、时间对纳米硒化镉晶粒有一定程度的影响．通过控制适当的反应条件，可制得纳米硒化镉溶胶。     

界面层中模型高分子链构象的统计理论

高分子自由链在溶液、熔体或固体中的构象有完整的理论和实验工作 ,已是成熟的知识[1～ 4] .近年来 ,受限大分子构象的探索已成为新的热点[5] .界面是一种最简单的限制 ,将对其附近的高分子产生显著的影响 .除理论家的重视以外 ,界面附近高分子构象问题还与许多应用领域相关 .例如 ,液体高分子的表面张力 ,固体高分子的粘附 ,滑移 ,磨蚀等力学特性 ,甚至它们的光学和电学性质都与界面上的组成和分子构象相关[6] .ｄｅＧｅｎｎｅｓ[7] 最早强调界面附近的分子链构象问题的重要性 .他首先从理论上猜测长链的链端若与界面有强吸引作用 ,则它们…     

Effect of microdomain structure on the mechanical behavior of binary blends

The relationship between microphase structure and mechanical response of the binary blends consisting of polystyrene-block-polyisoprene-block-polystyrene copolymer and low molecular weight polystyrene has been investigated. Low molecular weight polystyrene was chosen to obtain uniformly solubilized nano-blends without macrophase separation. The specimens were solution-cast by adding different amounts of homo-polystyrene to acquire different microphase structures. Small angle X-ray scattering(SAXS), transmission electron microscopy(TEM) and atom force microscopy(AFM) have been used to study the microdomain and grain structure. It is observed that the structural changes in d-spacing and grain size on account of different amounts of polystyrene alter the mechanical behavior in both monotonic tensile and cyclic tests. The elastic and the Mullins effects are strongly sensitive to the changes in d-spacing and grain sizes. Moreover, the sample with bi-continuous structure shows the largest tensile strength and Mullins effect. In addition, the Mooneye-Rivlin phenomenological model was used to evaluate and explore the relationship between the polymer topological networks and the rubber elasticity of these styrenic nano-blends.     

Simultaneous Improvements of Thermal Stability and Mechanical Properties of Poly（propylene carbonate） via Incorporation of Environmental-friendly Polydopamine

Inspired by the photoprotection, radical scavenging of melanin together with versatile adhesive ability of mussel proteins, polydopamine（PDA） nanoparticles were successfully prepared and incorporated into environmentally friendly polymer, poly（propylene carbonate）（PPC） via solvent blending. The prepared composites exhibited excellent thermal stability in air and nitrogen atmosphere and extraordinary mechanical properties. The composites displayed eminent increase of temperature at 5% weight loss（T5%） by 30-100 K with 0.3 wt%-2.0 wt% loadings, meanwhile, the tensile strength and Young＇s modulus were significantly improved from 11.5 MPa and 553.7 MPa to 40.5 MPa and 2411.2 MPa, respectively. The kinetic calculation indicated that improvement of T5% is presumably derived from suppressing chain-end unzipping. The glass transition temperature（Tg） of the PPC/PDA composites increased by 8-10 K. This is probably due to hydrogen bonding interaction since the abundant proton donors along PDA chains would interact with proton acceptors like C = O and C―O―C in PPC which would cause restriction of segmental motion of PPC chains.     

通过高速挤出制备高性能PBS/PETG共混材料

通过高速挤出技术制备了高性能聚丁二酸丁二醇(PBS)/聚(乙二醇-co-环己烷-1, 4-二甲醇对苯二酸酯)(PETG)共混材料,研究了不同PETG含量和不同螺杆转速对共混材料相区尺寸和性能的影响.研究发现PETG质量分数存在一个最佳用量:即为20%时,随着转速的提高PETG分散相相尺寸从最初的2.27μm逐渐降低到0.89μm.与此同时,共混材料的屈服强度从最初的26.2 MPa增加到33.4 MPa,提高了27.5%.断裂伸长率也从最初的13.3%提高到133.3%,实现了从脆性断裂到韧性断裂的转变.而当PETG的质量分数为10%或30%时,提高转速对PETG分散相的相尺寸减少不多,对共混材料力学性能有一定提升.最佳用量的存在表明高速挤出引起的相区尺寸减少是一个破碎与聚并动态平衡的过程.将不同的组成和加工的转速下获得的共混物的屈服强度与分散尺寸作图,发现它们成近似的反比关系,进一步证明PETG减小分散相相尺寸对共混材料性能提升的重要性.