Thermodynamic properties of aqueous mixtures of LiCl and Li2SO4 at different temperatures

Emf measurements were made on the cell without liquid junction: Li?ISE LiCl(m₁), Li₂SO₄(m₂) Ag/AgCl. The performances of the electrode pairs constructed in our laboratory were tested and exhibited near-Nernstian behavior. The mean activity coefficients of LiCl for the system Li⁺?Cl^??SO ₄ ^2? ?H₂O have been investigated by the emf values at temperatures of 0, 15, 35°C and constant total ionic strengths of 0.05, 0.1, 0.5, 1.0, 2.0, 3.0 and 5.0 mol·kg^?1. The activity coefficients decrease with increasing temperature and the ionic strength fraction of Li₂SO₄ in the mixtures. The thermodynamic properties are interpreted by use of Harned's empirical equations and Pitzer's ion interaction approach including the contribution of higher order electrostatic terms. The experimental results obey Harned's rule and are described by using Pitzer equations satisfactorily. The activity coefficients of Li₂SO₄, the osmotic coefficients and the excess free energies of mixing for the system in the experimental temperature range were reported.     

一类新型杂环聚芳酰胺的合成与性能研究

采用二氮杂萘类双酚 4 (4 羟基苯基 ) 2 ,3 二氮杂萘 1 酮 (DHPZ)与对氯苯腈反应制得二腈化合物 ,进一步水解为二酸 .以此新型二酸与不同二胺聚合制得的聚芳酰胺均具有较高的耐热性能 ,其Tg 在 2 91～318℃ ,且易溶于极性非质子溶剂中 .聚合物的特性粘数为 1 17～ 1 5 0dL g(2 5℃ ,0 5 %inNMP) ,对所得聚酰胺进行性能研究 ,其拉伸强度为 71～ 86MPa ,断裂伸长率为 8%～ 13% ,拉伸模量为 0 86～ 1 0 2GPa ,电阻系数数量级为 10 1 4～ 10     

KCl-LiCl-H2O体系热力学性质的研究

用K-ISE、Li-ISE和Cl-ISE测定了25 ℃时体系中KCl、LiCl的平均活度系数, 溶液的离子强度从0.1～4.0 mol·kg~(-1), 组成范围从纯的KCl到纯的LiCl。将Pitzer方程应用于测定结果, 用多元线性回归方法求出了Pitzer参数。     

可逆反应的热静力学研究法

化学反应的焓变△H和平衡常数K的测定是热静力学研究的重要任务。通常用量热法可以此较准确地测定△H,但要从量热数据直接得到K则是在六十年代初才开始有所探索。在达方面,Drago和Christensen的工作是值得借鉴的。本文建立了一种中性配位体与一价金属离子络合反应体系的热静力学研究法,并用这种方法研究了二苯并18-冠-6与Na~+的络合反应,同时得到了反应的△H和平衡常数K。实验值与文献值符合。     

增塑剂对1,1,1-三[1′-(2′-氧杂-4′-氧代-5′-氮杂-5′-甲基)十二烷基]丙烷PVC膜钠离子电极性能的影响

以1,1,1-三[1′-(2′-氧杂-4′-氧代-5′-氮杂-5′-甲基)十二烷基]丙烷(即ETH 227,Fluka No.71732)为中性载体的钠离子选择电极由于具有较强的抗钾离子干扰的能力,因而颇受注意。Guggi等首先用邻硝基苯辛醚和癸二酸二丁酯增塑,以合成的ETH227制成了K_((Na)~+,K~+)~(pot),<<10~(-2)的PVC膜钠离子电极.Jenny等以癸二酸二异辛酯为增塑剂,     

Z-scheme CuFe2O4–TiO2 nanocomposite microspheres for the photodegradation of methylene blue

Research on Chemical Intermediates - The design and synthesis of effective photocatalysts for photodegradation of persistent organic pollutants is of significant importance. Novel CuFe2O4...     

振动时效的动应力判据

采用多元非线性回归分析方法，求得振动时效试验中动应力σｄ，载荷次数ｎ和残余应力当量ｋ对消应力效果εｖ的经验方程。从而实现用动应力现场速测来定量评定振动时效工艺效果。本文主要介绍动应力判据方程的建立方法及其应用。     

纳秒激光诱导等离子体发射光谱中的自吸收效应

为了减小激光诱导等离子体发射光谱中光谱线的自吸收效应,提高激光光谱分析技术对物质中高含量元素的检测水平,实验采用了一种平面反射镜装置约束等离子体,比较了有或无平面反射镜装置时光谱线的线型变化。实验表明,在无平面反射镜装置时,样品元素Al,Mg和Mn的光谱线半高全宽度分别为0.16,0.24,0.058nm,而采用由四块平面反射镜组成的装置在空间上约束激光等离子体时分别为0.11,0.13,0.047nm。结果表明,光谱线的自吸收明显减小,谱线线型变得比较锐且强度显著提高。通过观测等离子体照片,测量等离子体温度和电子密度,分析讨论了激光光谱自吸收效应降低的原因。     

Improved cellular response on multiwalled carbon nanotube-incorporated electrospun polyvinyl alcohol/chitosan nanofibrous scaffolds

We report the fabrication of multiwalled carbon nanotube (MWCNT)-incorporated electrospun polyvinyl alcohol (PVA)/chitosan (CS) nanofibers with improved cellular response for potential tissue engineering applications. In this study, smooth and uniform PVA/CS and PVA/CS/MWCNTs nanofibers with water stability were formed by electrospinning, followed by crosslinking with glutaraldehyde vapor. The morphology, structure, and mechanical properties of the formed electrospun fibrous mats were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and mechanical testing, respectively. We showed that the incorporation of MWCNTs did not appreciably affect the morphology of the PVA/CS nanofibers; importantly the protein adsorption ability of the nanofibers was significantly improved. In vitro cell culture of mouse fibroblasts (L929) seeded onto the electrospun scaffolds showed that the incorporation of MWCNTs into the PVA/CS nanofibers significantly promoted cell proliferation. Results from this study hence suggest that MWCNT-incorporated PVA/CS nanofibrous scaffolds with small diameters (around 160 nm) and high porosity can mimic the natural extracellular matrix well, and potentially provide many possibilities for applications in the fields of tissue engineering and regenerative medicine.     

The electrochemical and mechanical properties of Ti incorporated amorphous carbon films in Hanks’ solution

Ti incorporated amorphous carbon (a-C) films with variant Ti contents were prepared by the unbalanced magnetron sputtering process. Scanning electron microscopy, ultraviolet Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy were used to characterize the microstructure of a-C films. The hardness and lubricated tribological properties were assessed using nanoindentation and ball-on-disk tribometer. As the Ti content in a-C films increases from 0 to 15.2 at.%, the sp³ volume fraction, the internal stress and the hardness of the films decreases gradually, while the disorder of sp² bond increases. The electrochemical tests reveal that the a-C films with lower than 1.5 at.% Ti possess good corrosion resistance in Hanks’ solution, while the a-C film with 15.2 at.% Ti is susceptible to crevice corrosion. The reduced friction of the a-C films is due to the sp² bonded film surface and boundary lubrication of the Hanks’ solution. The a-C film with 3.1 at.% Ti exhibits the best wear resistance in Hanks’ solution among the studied films.