Study of thermally coupled distillation systems for energy-efficient distillation

Distillation is one of the most widely used separation unit operations in process industries, although it is quite energy intensive. In many cases, the enormous energy requirements for distillation make it economically infeasible to carry out the separation. Thermally coupled distillation system (TCDS) is an advanced distillation method that provides significant energy savings of about 30% as compared with conventional distillation column sequences. The most well-known TCDS sequence, the Petlyuk configuration, has some operational challenges due to bidirectional vapour flow, which makes its implementation difficult in two-column mode. To overcome these limitations, a number of unidirectional vapour flow configurations have been proposed in the literature. The work on simulation analysis for such configurations is limited. In this paper, simulation models for two such configurations are developed, analyzed and compared with the Petlyuk and conventional distillation column sequences for separation of equimolar mixture of benzene–toluene–ethylbenzene.     

p型SiC欧姆接触理论及研究进展

碳化硅(SiC)具有宽禁带、高临界击穿电场、高热导率等优异特性,是制备高温、高频、大功率器件最理想的半导体材料之一。然而,制备良好的SiC欧姆接触尤其是p型SiC欧姆接触仍然是SiC器件研制中亟需攻克的关键技术难题。首先对p型SiC欧姆接触的形成机制及金属/SiC接触势垒理论进行了深入分析。然后,对近年来p型SiC欧姆接触的重要研究进展进行了综述,包括形成欧姆接触的金属体系,制备工艺条件,获得的比接触电阻率等,并重点讨论了p型SiC欧姆接触的形成机理。最后,对未来p型SiC欧姆接触的研究方向进行了展望。     

Validity and utility of a multidimensional model of received support in intimate relationships.

The authors of the present study statistically address the largely conceptual debate about the multidimensional nature of received support in intimate relationships. The Support in Intimate Relationships Rating Scale (SIRRS) was factor analyzed in 3 samples of dating and married couples. A novel, 4-factor structure of support types was generated that constituted esteem/emotional, physical comfort, informational, and tangible support types. This structure was reliable and valid in dating and marital relationships, across men and women, and across time. Each support type also demonstrated incremental validity for explaining marital adjustment, depression symptoms, and anxiety symptoms longitudinally. This study is among the first to generate and cross-validate a factor analytically derived set of support types for received support and the first to do so regarding partner support specifically. This is also the first study to replicate a distinct set of support types across different types of intimate relationships, across both sexes, and over time within relationships. Implications for enhancing functional theories of support and for augmenting the construct validity of a multidimensional model of received support are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

角抽运全固态激光器的研究进展

报道了清华大学光子与电子技术研究中心近年来在角抽运全固态激光器方面的研究成果,其中包括大功率全固态角抽运Yb:YAG激光器的研制,全固态角抽运Yb:YAG绿光激光器的研制以及中小功率全固态角抽运Nd:YAG基模激光器的研制.     

Water–based synthesis of La0,5Sr0,5CoO3 (LSCO) electrodes for ferroelectric thin films

Abstract

La_0,5Sr_0,5CoO₃ (LSCO) thin films were prepared from water solutions of lanthanum nitrate La(NO₃)₃x6H₂O, strontium nitrate Sr(NO₃)₂ and cobalt nitrate Co(NO₃)₂x6H₂O with different amounts of polyvinylalcohol (PVA). Thin films were deposited on platinum coated and thermally oxidized silicon substrates. The influence of the amount of PVA on the thermal decomposition of LSCO precursors, the surface wetting and the microstructure of LSCO thin films were investigated. The effort was also focused on the optimization of the thermal treatment to obtain dense LSCO thin films.     

Effect of isothermal aging and low density current on intermetallic compound growth rate in lead-free solder interface

This study investigated the effects of isothermal aging and low density current on intermetallic compound (IMC) growth rate and microstructural evolution of lead-free solder interface at a temperature of 398 K. The results showed that the morphology of IMC layers under high temperature aging and current stressing was basically same. The growth rate of IMC at the anode was the fastest. That was because chemical diffusion force and electronic wind acted together to drive the growth of IMC at the anode. The current density was not high enough for obvious polarization effects and crack along the electron flow direction to be observed. Next the mean-time-to-failure analysis was used to calculate the lifetime of ball grid array solder joints stressed electrically. However, the calculated value was much shorter than the true value. Indicating that perhaps the equation needs to be modified when applied to Cu interconnects and flip chip solder joints.     

Ti3SiC2-Cu composites by mechanical milling and spark plasma sintering: Possible microstructure formation scenarios

We present several possible microstructure development scenarios in Ti₃SiC₂-Cu composites during mechanical milling and Spark Plasma Sintering (SPS). We have studied the effect of in situ consolidation during milling of Ti₃SiC₂ and Cu powders and melting of the Cu matrix during the SPS on the hardness and electrical conductivity of the sintered materials. Under low-energy milling, (3–5) vol.%Ti₃SiC₂-Cu composite particles of platelet morphology formed, which could be easily SPS-ed to 92–95% relative density. Under high-energy milling, millimeter-scale (3–5) vol.%Ti₃SiC₂-Cu granules formed as a result of in situ consolidation and presented a challenge to be sintered into a bulk fully dense sample; the corresponding SPS-ed compacts demonstrated a finer-grained Cu matrix and more significant levels of hardening compared to composites of the same composition processed by low-energy milling. The 3 vol.% Ti₃SiC₂-Cu in situ consolidated and Spark Plasma Sintered granules showed an extremely high hardness of 227 HV. High electrical conductivity of the Ti₃SiC₂-Cu composites sintered from the granules was an indication of efficient sintering of the granules to each other. Partial melting of the Cu matrix, if induced during the SPS, compromised the phase stability and uniformity of the microstructure of the Ti₃SiC₂-Cu composites and thus it is not to be suggested as a pathway to enhanced densification in this system.     

Charakterisierung von Rohmaterialien für die Eisenerzherstellung mit Bildverarbeitung

The automatic image processing software VisuMet was developed during the projects KnetMet and K1-Met (2008–2012). VisuMet evaluates the quality of lump iron ore and fine iron ore. During the K1-Met (2012–2015), the programme will be further developed for pellets and sinter. The reduction degree is calculated with image processing and linear regression for semi- and reduced material of standard reduction tests. For the evaluation of pellets, the concentric phase front movement algorithms has to be adapted in order get a context between porosity and glass phase. These parameters are essential.     

Boosting the Performance of ZnO/CdS Core-Shell Nanorod Array-based Solar Cells by ZnS Surface Treatment

With a view to enhancing the efficiency of ZnO/CdS core-shell nanorod array-based semiconductor sensitized solar cells (SSSCs), ZnS surface treatment is envisioned. It is achieved through a thin layer of ZnS being deposited onto ZnO/CdS film by a successive ionic layer adsorption and reaction (SILAR) technique. To ascertain the optimum thickness of ZnS and to enhance the solar cell performance, we have varied the number of SILAR cycles of ZnS deposition. The optimized film is then considered for structural, morphological, and electrochemical studies. The analysis reveals the benefits of ZnS surface treatment on ZnO/CdS core-shell photoelectrodes in terms of an enhancement of solar cell performance of up to 1.54 % from 1.23 %.     

Dopamine-Based High-Transparent Hydrogel as Bioadhesive for Sutureless Ocular Tissue Repair

Ocular injuries and their complications represent the most common causes of visual impairment. For ocular surgery, there is an unmet need for highly transparent bioadhesives with superior adhesion, biocompatibility, and regenerative properties. Herein, a novel high-transparent bioadhesive hydrogel composed of gelatin methacryloyl (GelMA) and dopamine methacrylamide (DMA) is developed by in situ oxidative free-radical polymerization. This bioadhesive hydrogel overcomes the fundamental weakness of mussel-inspired adhesive copolymers in clinical practice by combining multiple favorable properties, including high light transmission, mechanical strength, adhesive strength, and biocompatibility. DMA significantly enhances corneal epithelial cells adhesion, proliferation, and migration on GelMA, and prevents the accumulation of reactive oxygen species (ROS) in corneal epithelial cells. In rabbit models of corneal and conjunctiva transplantation, the bioadhesive is able to decrease the inflammatory response and fibrosis formation induced by suture surgical trauma. In addition, the rabbit corneal stromal defect model reveals that the Gel/DMA bioadhesive could effectively seal corneal defects, accelerates corneal re-epithelialization, and promotes wound healing. Thus, given the advantages of high bioactivity and simple preparation, the Gel/DMA bioadhesive represents a promising strategy for suture-free ocular repair.