大学有机化学实验教学之我见

从有机实验课教学的重要性、有机实验报告的书写与批改、有机实验开放实验课的开设和有机实验成绩的评定等几方面对有机实验教学发表了自己的看法,并提出了自己的建议。     

无机化学实验教学初探

无机化学实验是化学教育的重要组成部分,对于培养学生发现问题、解决问题的能力以及创新能力,提高学生对化学学科的学习兴趣具有非常重要的作用。这门课程的教学是以学生为主体,指导教师为主导。本文主要探讨教学内容的优化,以及如何保证教学质量等等方面,旨在提高这门课程的教学质量。     

Different shades of red: The complexity of mineralogical and physico-chemical factors influencing the colour of ceramics

Different techniques (X-ray diffraction, field emission scanning electron microscope, colorimetry, visible-near infrared reflectance spectroscopy) were carried out to investigate the cause of colour changes of traditional ceramic materials. Two clayey materials of different composition, collected in the Bay of Naples, were fired in oxidising atmosphere at different temperatures resulting in different shades of red colour.Hematite is responsible of the reddish hue of ceramics and its nucleation is strictly related to firing temperature and chemical composition of the raw materials. A low CaO concentration allowed hematite to form in higher amounts providing a more intense reddish hue at high firing temperatures (over 950 °C). At the highest temperature (1100 °C) all samples showed darker colour due to increased size of iron oxide particles. Black core developed in Ca-rich ceramics fired at low temperatures as the short time of firing is insufficient to complete iron oxidation within the matrix, except in those containing high temper amounts. Indeed, microstructural modification occurs due to the presence of discontinuities among temper grains and matrix, which improves the circulation of oxygen in the core of ceramics.     

电解锰渣制备微晶玻璃正交实验研究

将煅烧后的电解锰渣作为单一的实验原料,采用烧结法,制备微晶玻璃,通过正交实验对锰渣微晶玻璃的热处理方案及性能进行探讨。实验通过DSC、XRD、SEM等方法对样品的性能进行表征,并测试了样品的体积密度、抗弯强度等性能。结果显示:不同的热处理条件下的锰渣微晶玻璃的主晶相均为透辉石(含铁),次晶相为普通辉石相。在800℃/0.5 h+980℃/1 h的热处理条件下得到的锰渣微晶玻璃的综合性能最优,其抗弯强度为106.82 MPa;体积密度为2.68 g/cm^3;维氏硬度为4.43 GPa;耐酸度为0.71%;耐碱度为0.07%。此外,锰渣微晶玻璃用作建筑材料,有非常大的应用潜力。     

均匀设计法在烷基糖苷合成中的应用

在烷基糖苷的合成反应中，影响糖苷得率的因素很多，且各因素之间又存在着相互牵制作用。为了探索合成的最佳条件，我们采用了均匀实验设计法。实验证明：它特别适用于多因素多水平的实验设计，同时减少了实验的次数，降低了实验的费用，提高了工作效率。     

冲突中的释放——中国当代陶艺的现代观念

中国当代陶艺的发生和发展,是在中国社会变革和中国当代艺术背景下架构的,它是一种现代艺术视觉观念的承载体,它切合了当代艺术的本质,成为一种特殊的文化,它自身所具有的对社会文化的“阻断性”和“冲击力”,以及所面临的当下“新艺术观念”的挑战中,在冲突和选择的临界点上,直呈时代文化状态的性质更加特征化了。     

FLOW OF NEWTONIAN FLUIDS THROUGH SINUSOID ALLY CONSTRICTED TUBES. NUMERICAL AND EXPERIMENTAL RESULTS

Numerical and experimental predictions of pressure drops in the flow of Newtonian fluids through sinusoidally constricted tubes (SCT) are carried out. The numerical evaluations analyzed in this work are obtained from the following methods: Geometric Iteration (GJM), Geometric Iteration with First and Second Upwinds (GIM1, GIM2), Successive Over Relaxation by Line (SORBLM), Global Galerkin Spectral Method (GGSM), Collocation (CM) and Dufort-Frankel (DFM). The GIM1, GIM2 and SORBLM are applied to SCT and explained in this work. The other methods have been previously reported in the literature with the same purpose. Experiments are accomplished for constrictions of approximately 40,60 and 80% of the average tube diameter and results compare well with numerical predictions of the steady flow. It is concluded that special attention should be given to evaluations of the friction factor ƒ for Reynolds numbers Re between the onsets of flow separation and turbulence due to flow instability. Finally, the SCT as a model for porous media (PM) is discussed.     

工艺条件及稳定剂对CPVC透光率的影响

研究混料时间、混料温度、热稳定剂含量和模压时间对氯化聚氯乙烯(CPVC)透光率的影响,并通过正交试验法优化其加工工艺条件与热稳定剂含量。首先通过单因素实验研究了每个因素对实验结果的影响,并在每组实验中选取3个最优水平,然后通过正交试验法优化最佳实验条件。结果表明,适度提高混料时间、混料温度、热稳定剂含量和模压时间,有助于提高CPVC的透光率。正交试验结果表明最佳条件为:混料时间5 min,混料温度190℃,有机锡含量5%,模压时间5 min。在该实验条件下,制得的CPVC透光率为85.6%。     

Convective Drying of Agitated Silica Gel and Beech Wood Particle Beds—Experiments and Transient DEM-CFD Simulations

With coupled discrete element (DEM)–computational fluid dynamics (CFD) simulations, drying processes can be simultaneously described on the system scale while resolving detailed subprocesses on the particle scale. In this contribution, DEM-CFD simulations are used to analyze the transient heat and mass transfer in mechanically agitated particle beds during drying. Results are compared to convective batch-drying experiments with silica gel and beech wood spheres and mixing effects are studied in detail. A good agreement with the measurements of both single-particle and particle bed drying is achieved by resolving heat and moisture transport three-dimensionally inside each particle.     

超零界二氧化碳无水压裂增稠剂实验研究

二氧化碳在温度高于临界温度Tc=31.26℃,压力高于临界压力Pc=7.4 MPa的状态下,性质会发生变化,变化为一种介于气体与液体之间的流体,其密度近于液体,粘度近于气体,扩散系数为液体的100倍,因而具有惊人的溶解与渗透能力。将其与增稠剂混合,使其在高温高压下仍能保持高黏度,耐剪切性、流变性、悬砂性等性能良好的压裂体系,渗透至岩石天然裂缝中,利于复杂网格裂缝的形成,并且由于其超低的界面张力可以做到无残渣易反排,降低对储层的伤害。