优化实验室管理提高实验室投资效益

当前必须加强实验室的科学化管理,组建一支精通业务、踏实肯干、运转和谐的科研师资队伍,保持仪器最佳的使用状态,找到最佳使用途径,最大限度地发挥实验设备的作用,提高实验室投资效益.高校实验室在硬件建设的基础上,如何从软件管理上讲效益,要收益,即如何加强实验室的科学化管理,建设一支精干的服务于实验室的科研师资队伍,最大限度地发挥实验仪器的作用,提高实验室投资效益,是个必须探讨的问题.     

红外成像导引头双视场光学系统小型化技术

红外成像导引头越来越广泛地采用双视场光学系统,但光学系统性能与体积之间的矛盾非常突出。通过分析导引头红外变倍光学系统和一般红外系统的区别,阐明了导引头双视场光学系统的特点,在保证性能指标的前提下,介绍了通过采取出瞳与冷屏合适的匹配方式、优化变焦结构、采取红外新技术等有效减小红外变倍系统体积的几种方法,并对其进行了公式推导和证明,给出了计算实例,同时阐明了优化总体指标,使导引头总体性能最优的观点。     

利用组成型表达载体pMG36e电转化德式乳杆菌保加利亚亚种的研究

以典型的乳酸菌组成型表达质粒pMG36e为载体,德式乳杆菌保加利亚亚种为受体.采用电转化方法研究受体菌株的生长状态与细胞壁处理方式、质粒浓度、电转化参数、复苏培养基组成与复苏培养时间、受体菌株的限制修饰作用对电转化效率的影响,探讨电转化的最适条件,以提高电转化效率.结果表明:选择含2.5%甘氨酸的SMRS培养基培养受体细胞至对数中期,收获制成感受态细胞,在电场强度12 kV/cm、电阻200Ω、电容25μF条件下电击转化,以含20 mmol/L MgCl2、CaCl2的SMRS培养基复苏培养2 h,涂板筛选得到较高的电转化效率.特别是采用受体菌株修饰的质粒进行电转化,转化效率提高30倍以上,达到6.3×104cfu/μg DNA.本研究结果为进一步构建乳酸菌组成型高效表达系统和食品级基因工程乳酸菌株提供试验依据.     

Urea-N recycling in lactating dairy cows fed diets with 2 different levels of dietary crude protein and starch with or without monensin

Rumensin (monensin; Elanco Animal Health, Greenfield, IN) has been shown to reduce ammonia production and microbial populations in vitro; thus, it would be assumed to reduce ruminal ammonia production and subsequent urea production and consequently affect urea recycling. The objective of this experiment was to determine the effects of 2 levels of dietary crude protein (CP) and 2 levels of starch, with and without Rumensin on urea-N recycling in lactating dairy cattle. Twelve lactating Holstein dairy cows (107 ± 21 d in milk, 647 kg ± 37 kg of body weight) were fed diets characterized as having high (16.7%) or low (15.3%) CP with or without Rumensin, while dietary starch levels (23 vs. 29%) were varied between 2 feeding periods with at least 7 d of adaptation between measurements. Cows assigned to high or low protein and to Rumensin or no Rumensin remained on those treatments to avoid carryover effects. The diets consisted of approximately 40% corn silage, 20% alfalfa hay, and 40% concentrate mix specific to the treatment diets, with 0.5 kg of wheat straw added to the high starch diets to enhance effective fiber intake. The diets were formulated using Cornell Net Carbohydrate and Protein System (version 6.1), and the low-protein diets were formulated to be deficient for rumen ammonia to create conditions that should enhance the demand for urea recycling. The high-protein diets were formulated to be positive for both rumen ammonia and metabolizable protein. Rumen fluid, urine, feces, and milk samples were collected before and after a 72-h continuous jugular infusion of ¹⁵N¹⁵N-urea. Total urine and feces were collected during the urea infusions for N balance measurements. Milk yield and dry matter intake were improved in cows fed the higher level of dietary CP and by Rumensin. Ruminal ammonia and milk and plasma urea nitrogen concentrations corresponded to dietary CP concentration. As has been shown in vitro, Rumensin reduced rumen ammonia concentration by approximately 23% but did not affect urea entry rate or gastrointestinal entry rate. Urea entry rate averaged approximately 57% of total N intake for cattle with and without Rumensin, and gastrointestinal rate was similar at 43 and 42% of N intake for cattle fed and not fed Rumensin, respectively. The cattle fed the high-protein diet had a 25% increase in urea entry rate and no effect of starch level was observed for any recycling parameters. Contrary to our hypothesis, Rumensin did not alter urea production and recycling.     

半干法制备低取代度阳离子淀粉的工艺研究

以玉米淀粉为原料,以3-氯-2羟丙基三甲基氯化铵(CHPTMA)为醚化剂,以NaOH为催化剂的条件下,半干法制备了低取代度阳离子淀粉。确定了半干法制备低取代度阳离子淀粉的工艺路线,研究了各反应因素对阳离子淀粉反应效率的影响,并以反应效率为指标,利用二次通用旋转试验建立了相应的回归方程,确定了最佳工艺参数为:NaOH与醚化剂的摩尔比1.85∶1,体系含水量20.49%,反应温度60.65℃,反应时间4.49h,最佳条件下制备的阳离子淀粉反应效率可达到89.48%,取代度为0.0335。     

我国冬油菜区土壤肥力变化及施肥效果演变

本文分析了1961—1965年、1981—1985年及2004—2006年3个时期我国冬油菜种植区的土壤肥力状况,氮、磷、钾及硼肥的施用效果,氮、磷、钾肥的农学效率及肥料贡献率。结果表明,与20世纪60年代相比,近期油菜主产区耕地土壤有机质、全氮、碱解氮、速效磷及有效硼含量大幅度上升;土壤有机质、速效磷及有效硼含量较20世纪80年代也略有增加。但由于土壤养分临界值水平的提高,近期土壤有效氮、磷、钾、硼的缺乏范围存在扩大趋势。田间肥效试验结果表明,以增产量为标准,近期施用氮、磷、钾、硼油菜籽增产高于其它两个时期。施肥在油菜籽产量中的贡献率从1961—1965年间的23．8％和1981—1985年间的54．5％增长到2004—2006年间的55．1％。总体上,我国冬油菜种植区土壤养分肥力稳中有升,但速效养分相对缺乏面积扩大;施肥对油菜籽单产的贡献率增大,油菜丰产必须建立在科学施肥的基础上。     

PPS/PTFE纤维复合水刺耐高温过滤材料的制备与性能研究

将PPS/PTFE纤网用水刺工艺覆盖在经过预针刺的"夹心层"结构的PPS纤网上,制得复合水刺滤料。试制了三种不同PPS/PTFE混合比的复合滤料,并测试了其基本性能和过滤性能。结果表明:PPS纤维与PTFE纤维的混合比对复合水刺滤料的性能有一定影响;该滤料具有高效率、低阻力、长寿命和耐高温等优良性能,可应用于高温除尘过滤领域;采用水刺工艺加工PPS/PTEF纤维复合耐高温滤料可以降低滤料的生产成本和提高其过滤性能。     

葡糖醋杆菌利用黄水发酵生产细菌纤维素

为探究葡糖醋杆菌（Gluconacetobacter）利用黄水生产细菌纤维素的可行性,将黄水按不同体积比添加到传统发酵液（HS培养基）中,接种葡糖醋杆菌至发酵液中30 ℃静置培养7 d,测定发酵过程中的细菌纤维素产量、还原糖含量等理化指标。结果表明,在HS培养基中添加黄水可以显著地增加细菌纤维素的产量（P＜0.05）,黄水的最佳体积比为40%。在此条件下,细菌纤维素产量为5.93 g/L,比HS培养基（2.20 g/L）提高了169.5%;糖转化效率提高了148.9%;从第2天开始,单日细菌纤维素产量均＞0.70 g/L,第5天产量最高为1.14 g/L,单日糖转化效率均高于同时期的HS培养基;pH值维持在4.60～5.50之间。在扩大浅圆盘发酵中,40%黄水-HS培养基中细菌纤维产量为3.48 g/L,比HS培养基（1.62 g/L）提高了114.8%。