使用超声搅拌实现精密KOH各向异性体硅腐蚀

对使用超声搅拌和不加搅拌时(100)单晶硅的腐蚀特性进行了研究和对比.使用超声搅拌,可以得到光滑的、无小丘的腐蚀表面,整个硅片腐蚀深度的误差不超过1μm.实验结果表明,该方法可以有效地实现精密KOH各向异性体硅腐蚀.     

金源矿业公司充填系统搅拌桶改造实践

针对金源矿业公司充填系统在应用过程中出现的井下充填料浆离析、分层,充填体强度低等问题,认为充填系统搅拌桶设计不尽合理是其主要原因。通过搅拌桶叶轮设计及搅拌总成计算,对充填系统原搅拌桶进行了改造,并取得了较好的应用效果。     

集成电路塑封模具错位、偏心问题探讨

就集成电路封装过程中塑封模具的错位和偏心问题做探讨,分析导致错位和偏心的各种原因,并就如何使塑封模具的错位、偏心问题对产品的质量影响降到最低提出了具体的改善措施.     

气体搅拌萃取塔传质系数的研究

为研究萃取塔内气体搅拌对传质系数的影响,在萃取塔中用水萃取煤油中的苯甲酸的实验考察了液相流速、气体流速和内构件对传质系数的影响。实验结果表明,传质系数随水、油、气的表观流速的增加而增加,分散相表观流速对传质系数的影响大于连续相的表观流速;萃取塔内构件的不同组合方式对传质系数有一定的影响,其中以SL-SP-SL型组合方式的传质效果最好。     

In‐line mixing for production of citric acid by Candida lipolytica grown on n‐paraffins

This study reports on the effects of internal fermenter and external in‐line agitation and fed‐batch mode of operation on citric acid production from Candida lipolytica using n‐paraffin as the carbon source. An optimum range of fermenter agitation speeds in the range 800–1000 rpm corresponding to Reynolds numbers of 50433–62947 (based on initial batch conditions) seemed to give the best balance between substrate utilization for biomass growth and citric acid production. Proof of concept evidence is presented that indicates that an external in‐line agitator could be used in place of high speed internal agitation to increase citric acid production. However, more work is required to optimize the external agitator concept. Application of multiple fed‐batch feedings can be used to extend the batch fermentation and increase final citric acid concentrations and product yield. Experiments were conducted implementing a three‐cycle fed‐batch process which increased overall citric acid yields to 0.8–1.0 g citric acid g^?1 n‐paraffin, approximately 200% improvement from those found in the normal batch process. The three‐cycle fed‐batch mode of operation also increased the final citric acid concentration to 42 g dm^?3 from about 6 g dm^?3 for normal batch operation. Increased citric acid concentrations in three‐cycle fed‐batch mode was achieved at longer fermentation times. Copyright © 2004 Society of Chemical Industry     

An analysis of the eccentric nosing process of metal tubes

In this paper, the finite-element method is used to investigate the cold eccentric nosing process of metal tubes with an eccentric conical die from circular tube billets. A series of simulations on the eccentric tube nosing using the program DEFORM-3D was carried out. The influences of the process parameters such as tube length, tube thickness, die fillet radius, die angle, friction factor, strength coefficient and strain-hardening exponent of the billet material on the critical nosing ratio of the tube are examined.     

圆锥破碎机频发故障的剖析

通过对大型选矿设备———圆锥破碎机的受力分析，说明其频发故障的部位和机理，为保证机器的正常运转，在设计、制造中应当注意的问题。     

Changes in intracellular sodium and potassium in chemostat-cultivated Escherichia coli

Escherichia coli was continuously cultivated at constant dilution rate for a range of agitation rates, and at constant agitation rate over a range of dilution rates. Mean cell volume increased linearly both with increase in agitation rate (as we have previously found) and with increase in dilution rate. In each case, measurement of intracellular sodium and potassium content after rapid separation of cells from the medium by centrifugation through silicone oil showed these to increase as the mean cell volume increased. In absolute terms, the increase in sodium or potassium per unit cell volume was significantly greater for changes in agitation rate than for changes in dilution rate.     

A pneumatically agitated flat-panel photobioreactor with gas re-circulation: anaerobic photoheterotrophic cultivation of a purple non-sulfur bacterium

The application of hydrogen as a clean and efficient energy carrier in the near future becomes more and more evident. Within the process of photobiological hydrogen production, purple non-sulfur bacteria are an interesting subject of study because of their high hydrogen producing capacity. In a previous study, the used Rhodopseudomonas sp. had proven to efficiently produce hydrogen from acetic acid and light energy. We constructed a pneumatically agitated flat-panel photobioreactor as a model system for optimization of photoheterotrophic hydrogen production. Batch experiments and a chemostat experiment were performed to investigate the proper functioning of the new photobioreactor. During the first experiments, argon gas was sparged through the system for mixing and inhibition of growth was observed. Experimental results indicate that the stripping of carbon dioxide from the culture liquid caused this inhibition of growth. Possibly, the Rhodopseudomonas sp. used requires carbon dioxide during growth on a highly reduced substrate like acetate. Recirculating the gas prevented the carbon dioxide from being stripped from the system. In this mode of operation, growth was supported.