Rapid fermentation of beer using an immobilized yeast multistage bioreactor system

A multistage bioreactor system for rapid beer fermentation was developed. The main fermentation process, which conventionally requires 7 d, could be shortened to 2 d by this system. The concentration of esters and higher alcohols are major factors in brewery fermentation, their production being closely related to the yeast growth phase. Yeast metabolism was successfully subdivided into a growth and a restricted phase through a combination of a continuous stirredtank reactor (CSTR) and an immobilized yeast packed-bed reactor (PBR). Production of higher alcohols was high in the CSTR because of its association with the level of biosynthetic activityde novo. A small amount was also produced in the PBR, however, possibly a result of an overflow in carbohydrate metabolism. Ester formation mainly occurred in the PBR, a linear increase in the level of ester being observed with flow through the PBR. The reactor system control strategy was to maximize the level of both higher alcohol and ester formation. The CSTR/PBR control range, based on extract consumption, was varied between 1:1 and 1:2. A ratio of 1:1 tended to create a flat beer, whereas a ratio 1:2 gave a beer of richer quality. Amino acid uptake by the yeast directly contributed to a reduction in the wort pH, whereas no relation could be observed between the level of organic acid production and pH.     

Effects of humic acids and microorganisms on decabromodiphenyl ether, 4,4′-dibromodiphenyl ether and anthracene transportation in soil

In this study, effects of humic acids (HA) and microorganisms on the migration of hydrophobic organic contaminants (HOCs), decabromodiphenyl ether (BDE-209), 4,4′-dibromodiphenyl ether (BDE-15) and anthracene, in soils were examined. More soil particles were dispersed into the colloidal phase (0.22-1 μm) in the presence of HA and/or microorganisms as a result of increased erosion and friction. The study suggested that PBDEs (BDE-209 and BDE-15) and anthracene in soils would be transported to other places by...     

Effective Separation of Bacterial Phospholipids and Neutral Lipids in one Dimensional Thin Layer Chromatography

Abstract

A method for effective separation of phospholipids and neutral lipids of E. Coli in one dimensional thin layer chromatography on ready-made plates has been proposed. The chromatographing was made successively in three different solvent systems. About ten lipid components were shown to be separated on the same plate.     

Biodegradation of polyhydroxyalkanoates (PHAs) in tropical coastal waters and identification of PHA-degrading bacteria

Biodegradability patterns of two PHAs: a polymer of 3-hydroxybutyric acid (3-PHB) and a copolymer of 3-hydroxybutyric and 3-hydroxyvaleric acids (3-PHB/3-PHV) containing 11 mol% of hydroxyvalerate, were studied in the tropical marine environment, in the South China Sea (Nha Trang, Vietnam). No significant differences have been observed between degradation rates of 3-PHB and 3-PHB/3-PHV specimens; it has been found that under study conditions, biodegradation is rather influenced by the shape of the polymer item and the preparation technique than by the chemical composition of the polymer. Biodegradation rates of polymer films in seawater have been found to be higher than those of compacted pellets. As 3-PHB and 3-PHB/3-PHV are degraded and the specimens lose their mass, molecular weight of both polymers is decreased, i.e. polymer chains get destroyed. The polydispersity index of the PHAs grows significantly. However, the degree of crystallinity of both PHAs remains unchanged, i.e. the amorphous phase and the crystalline one are equally disintegrated. PHA-degrading microorganisms were isolated using the clear-zone technique, by inoculating the isolates onto mineral agar that contained PHA as sole carbon source. Based on the 16S rRNA analysis, the PHA-degrading strains were identified as Enterobacter sp. (four strains), Bacillus sp. and Gracilibacillus sp.     

基于仿生人工关节的评价装置及磨损试验研究

基于仿生人工关节结构,利用连杆机构模拟关节弯曲/拉伸运动方式建立了仿生人工关节评价装置,同时对以小牛血清作为润滑介质的氧化锆-超高分子量聚乙烯(ZrO-UHMWPE)人工关节配副进行磨损性能测试.结果表明:所建立的装置不仅可以加速考察人工关节配副的磨损特性,还能够加速评价仿生关节囊的动态疲劳性能,同时实现转速、载荷以及运动角度等参数可调并具有较强可操作性; UHMWPE的磨损量与运动周期近似呈线性关系,UHMWPE的体积磨损率相对稳定,约为70～80 mm3/106周期,且具有较好的重复性与可靠性.     

L-天门冬氨酸对三水碳酸镁晶体合成的影响研究

依据仿生合成的原理,选择无水MgCl2和无水Na2CO3作为反应原料,通过L-天门冬氨酸和五种无机表面活性剂分别对晶体生长进行调控,应用XRD、SEM对晶体的物相组成以及形貌结构进行表征.试验结果表明当表面活性剂为L-天门冬氨酸时,晶体生长效果最佳.又通过以L-天门冬氨酸添加量和体系pH值为参数变量进行研究,结果表明L-天门冬氨酸质量分数为0.15;,体系pH为9.5为最佳条件,有毫米级束状三水碳酸镁晶体的生成,并对L-天门冬氨酸在仿生合成三水碳酸镁过程中的作用机理进行了初步探讨.     

Teil I: Zu einigen Grundproblemen der Nahrungsmittelbestrahlung

In den vergangenen 10 bis 15 Jahren wurden in vielen Ländern umfangreiche wisseschaftlice und technische Forschungsarbeiten auf dem Gebiet der Haltbarkeitsverlängerung von Nahrungsmitteln durch Einwirkung ionisierender Strahlung begonnen. Waren es zunächst nur wenige Industrieländer (USA, UdSSR, England, Frankreich), in denen diese Problematik mit beträchtlichem Aufwand bearbeitet wurde, so schlossen sich ihnen nach dem Vorliegen erster positiver Forschungsergebnisse und aussichtsreicher ökonomischer Abschätzungen—etwa um 1960—eine Vielzahl weiterer Industrie- und Entwicklungsländer an. Inzwischen haben die Publikationen über die verschiedensten Aspekte und Bereiche der Nahrungsmittelbestrahlung einen kaum noch zu übersehenden Umfang angenommen. Aus diesem Grunde ist es schon heute nicht mehr möglich, im Rahmen einer Zeitschrift einen vollständigen Überblick über das Gesamtgebiet zu geben.     

中低速下干气密封型槽仿生改进研究

为解决干式气体端面密封在中低速或启动停车阶段密封性能不稳定的问题,在现有螺旋槽端面型槽结构的基础上借鉴仿生学设计方法提出了仿生多流通道螺旋槽干气密封端面结构.基于气体润滑理论模型,采用数值分析方法计算了气体端面气膜压力控制方程-雷诺方程,研究对比了普通螺旋槽和多流通道槽的端面压力分布.在改变操作参数和端面气膜厚度的条件下分析对比了普通螺旋槽和多流通道槽两种干气密封的开启力,泄漏率,刚度和刚漏比的变化规律,并研究了槽的通道数对密封性能的影响规律.结果表明:中低速下多流通道细长螺旋槽具有高的稳定性和好的密封性,汇流槽在增加密封稳定性的同时可降低泄漏率.     

Physical and microbial collection efficiencies of an electrostatic precipitator for abating airborne particulates in postharvest agricultural processing

We constructed a single-stage, laboratory-scale electrostatic precipitator (ESP) and evaluated its physical and microbial collection efficacies. Ground rice husk was examined as a representative model of airborne particles carrying microorganisms (bacteria, molds and yeasts). Physical and microbial collection efficacies were evaluated at different voltages applied to the negative discharge electrode without ozone generation. The best collection efficiencies were observed at an applied voltage of ?6.0 kV, resulting in collection efficiencies of over 90% for the physical sample and 99.95% for bacteria. No molds or yeasts in the ground rice husk passed through the ESP operating at ?6.0 kV applied voltage.     

激光处理凹坑形仿生非光滑表面试件的高温摩擦磨损特性研究

采用销-盘式摩擦磨损试验机,研究了经激光处理后不同直径和间距的W9Cr4V高速钢凹坑形非光滑试件在不同温度下的摩擦磨损特性.结果表明:在室温至500 ℃的试验条件下,非光滑试件的耐磨性随着温度的升高而降低,且在200 ℃以内非光滑试件的磨损量随着温度增加缓慢增大,当超过200 ℃以后,磨损量增加较快;不同尺寸及分布规律的非光滑凹坑对零件耐磨性的影响不同,在本次试验条件下,非光滑凹坑直径及其间距愈大,非光滑试件的耐磨性能愈好;温度愈高,非光滑试件摩擦系数愈小.