MTT法测定大肠杆菌活菌数实验研究

实验分析MTT比色法中的工作波长、反应时间、MTT用量、菌龄、二甲基亚砜（DMSO）等因素对大肠杆菌活细菌计数的影响.同时,通过与平板计数对比,确定了MTT细菌计数的可行性.结果表明,当细菌数在107～109cell·mL-1范围内时,双波长MTT法可用于检测大肠杆菌的活菌数量,最佳反应时间为60min,MTT溶液用量...     

2A12合金微弧氧化工艺因素的影响研究

针对2A12铝合金开展微弧氧化工艺研究,通过正交试验设计,从微观形貌、显微硬度、元素组成和相组成等方面分析了各因素对微弧氧化陶瓷膜性能的影响,并优化了2A12铝合金微弧氧化的工艺参数。结果表明,在Na2SiO3＋KOH＋添加剂的电解液中,影响2A12铝合金微弧氧化陶瓷膜综合性能的各因素显著顺序为：氧化时间〉电流密度〉频率〉KOH含量〉Na2SiO3含量〉添加剂含量;在优选工艺条件下制备的陶瓷膜层厚度可达120μm以上,致密层的显微硬度HV最高达1800以上。     

荧光法生物气溶胶监测仪标准物质研制及校准方法研究

生物气溶胶监测仪是利用激光或紫外光诱导生物粒子发射荧光,从而实现对空气中的生物气溶胶进行监测的仪器.目前,国内尚无生物气溶胶监测仪校准用标准物质和评价方法.以聚苯乙烯微球为核,通过Friedel-Crafts酰基化反应,研制出能够自身受激发产生荧光的聚苯乙烯(PS-PB)微球.PS-PB微球粒径分布的相对标准偏差为1....     

挤压变形对MB15镁合金及组织性能的影响

对MB15镁合金进行热处理,然后进行挤压试验,挤压变形MB15镁合金组织以剪切条纹和细小的α再结晶等轴晶为基本特征。挤压变形可显著地细化镁合金晶粒并提高镁合金的力学性能。随挤压比的增大,晶粒细化程度增加;强度、硬度随挤压比的增大而增大。所制定的工艺合理,挤压出的管材、型材有较好的力学性能。     

EGSB反应器初期启动颗粒污泥显微特征

EGSB反应器在常温下处理低浓度的污水以及高浓度难降解的工业废水方面有着其它厌氧反应器所不可比拟的优势.厌氧颗粒污泥是EGSB反应器高效稳定运行的关键,通过显微观察研究了EGSB反应器初期启动过程中颗粒污泥的特征.污泥颗粒化进展顺利标志着EGSB反应器初期启动成功.     

张八岭变质地体变质构造岩的显微构造与结构特征

本文在1／5万张八岭幅、珠龙幅区域地质调查基础上．运用微观构造与宏观构造相结合的方法，借助于现代测试技术．对张八岭变质地体山变质构造岩的显微构造与结构进行了研究。验证和深化了野外工作所观察到的现象和认识；探讨了应力和应变之间的关系；计算了差异流动古应力值；恢复了构造变动对岩石的应力状态和方位。     

油酸钠对餐厨垃圾两相厌氧发酵中利用乙酸产甲烷过程的影响

为了研究餐厨垃圾油脂中含有的长链脂肪酸(主要是油酸)对两相厌氧发酵中利用乙酸产甲烷过程的影响,采用中温(35±1)℃批式发酵,以浓度为10 g·L~(-1)的餐厨垃圾厌氧发酵产甲烷相出水为接种液,以乙酸为底物,考察了添加不同浓度油酸钠对累积甲烷产量、产甲烷古菌数量以及发酵过程中乙酸代谢和氢气分压的影响.结果表明:1产甲烷延滞期随油酸钠浓度增加而延长.2油酸钠浓度低于6.0 g·L~(-1)的处理组经过延滞期后乙酸代谢恢复正常,可以完全被转化为甲烷,且部分油酸钠也可被转化为甲烷;油酸钠浓度高于8.0 g·L~(-1)的处理组乙酸代谢受到严重抑制,只有少量甲烷生成;油酸钠生成中间代谢产物,且甲烷转化率为0.3油酸钠对厌氧发酵中产甲烷古菌有严重的抑制作用,产甲烷古菌数量大幅度减少是乙酸代谢过程受到抑制的主要原因.4油酸钠的添加量超过6.0 g·L~(-1)时,在发酵初期会引起产甲烷相中氢分压的升高,也证实了油酸钠对厌氧发酵的抑制作用.     

量子相干性对耦合双量子点全计数统计的影响

根据有效粒子数分辨的量子主方程的方法,研究了并联耦合双量子点系统电子的全计数统计。当量子点间的隧穿耦合强度与量子点电极的耦合强度的数值接近时,量子相干性,即系统约化密度矩阵的非对角元开始对系统的电子全计数统计特性起作用。特别是,量子点之间的隧穿耦合强度相对越弱,系统约化密度矩阵的非对角元对系统的电子全计数统计影响就越加明显;同时,量子点之间的隧穿耦合强度小到一定程度时,系统约化密度矩阵的非对角元对系统的电子全计数统计影响将会趋于稳定。     

春季预防流行性疾病常识

春季是呼吸道传染病的多发季节,因受季节的影响容易引发某些呼吸道传染病的局部流行。如流感、流脑、流腮、风疹等。这些传染病虽然具有一定的传染性,但只要预防得当,完全可以控制它的传播流行。     

Organic matter produced by algae and cyanobacteria: Quantitative and qualitative characterization

This work aims at characterizing organic matter produced by an alga Euglena gracilis and a cyanobacteria Microcystis aeruginosa and assessing the evolution of its characteristics during growth. A culture medium was optimized. The species growth phases were monitored using both visible spectrophotometry and flow cytometry cell counting. Organic matter fractionation according to hydrophobicity and specific UV absorbance (SUVA) index were used to specifically characterize the produced algal organic matter (AOM). The AOM characteristics were both growth phase and species dependent. However, a similar evolution was observed. The hydrophilic fraction (HPI) was the major fraction whatever the growth phases and was almost the only one produced during lag and exponential phases. It represented around 75% of AOM during exponential phase and then decreased when the stationary phase appeared. It represented 46% and 60% of the AOM during late decline phase for the cyanobacteria and the alga respectively. The hydrophobic (HPO) and transphilic (TPH) fractions started to appear from the beginning of the stationary phase with more hydrophobic compounds coming from intracellular organic material of dying cells. HPO and TPH percentages still increased during the decline phase probably because of two additional processes: photo-dissolution and leaching of particulate organic matter from cells fragments. A comparison of AOM during late decline phase and natural organic matter (NOM) from Glane River (France) underlined that AOM was more hydrophilic and presented a lower SUVA for each fractions than NOM. However, the difference between NOM and AOM hydrophobicity narrowed during decline phase.