Biodegradation of phenol and /w-cresol by mutated Candida tropicalis

The phenol and m-cresol biodegradations were studied using the mutant strain CTM 2 obtained by the He-Ne laser irradiation on wild-type Candida tropicalis. The results showed that C. tropicalis exhibited the increased capacity of phenolic compounds degradation after laser irradiation. It could degrade 2600 mg/L phenol and 300 mg/L m-cresol by 5% inoculum concentration, respectively. In the dual-substrate biodegradation system, 0-500 mg/L phenol could accelerate m-cresol biodegradation, and 300 mg/L m-cresol could be completely utilized within 46 hr at the presence of 350 mg/L phenol. Besides, the maximum biodegradation of m-cresol could reach 350 mg/L with 80 mg/L phenol within 61 hr. Obviously, phenol, as a growth substrate, could promote CTM 2 to degrade m-cresol, and was always preferentially utilized as carbon source. Comparatively, low-concentration m-cresol could result in a great inhibition on phenol degradation. In addition, the kinetic behaviors of cell growth and substrate biodegradation were described by kinetic model proposed in our laboratory.     

Screening for a new Streptomyces strain capable of e cient keratin degradation

Keratinous wastes could be degraded by some microorganisms in nature. Native human foot skin （NHFS） was used as sole nitrogen source to screen microorganisms with keratin-degrading capability. From approximately 200 strains, a strain of Streptomyces sp. strain No. 16 was found to possess the strongest keratinolytic activity, and the total activity in the culture was 110 KU/ml with specific activity of 2870 KU/mg protein （KU： keratinase unit）. Substrate specificity test indicated that the crude keratinase could degrade keratin azure, human hair, cock feathers and collagen. The optimal pH of the crude keratinase ranged from 7.5 to 10 and the temperature ranged from 40℃ to 55℃. Metal chelating agent ethylenediamine tetraacetic acid obviously stimulated the keratinolytic activity but suppressed the proteolytic activity. To our knowledge, this is the first report on specific induction of keratinases by NHFS from an actinomycete. Moreover, excellent characteristics of its crude keratinase may lead to the potential application in waste treatment and recovery, poultry and leather industry, medicine, and cosmetic development.     

低温条件下硝基苯降解菌的分离及降解特性

低温条件下,从东北制药总厂的曝气池与氯霉素生产废水集水池污泥中分离、筛选得到6株以硝基苯为唯一碳源的降解菌,对6株菌进行降解能力研究得知,菌株cc-2为低温高效硝基苯降解菌。经形态特征和生理生化特征分析,初步鉴定属于不动杆菌属(Acinetobacter sp.)。菌株cc-2降解性能研究结果表明:菌株最佳条件为生长温度15℃、培养基pH值为7、摇床转速为140 r/min。最佳降解条件下,当硝基苯初始浓度为200 mg/L时菌株48h降解率达66.84%。外加葡萄糖和乙酸钠促进了菌株cc-2对硝基苯的生物降解,降解率分别为80.44%和78.57%,该菌株的生长降解性能研究为低温环境中硝基苯的修复提供了技术支撑。     

海洋卡盾藻（香港株）溶血活性特征研究

研究了海洋卡盾藻香港株（Chattonella marina,Hong Kong strain,CMHK）在不同生长阶段和营养条件下的溶血活性特征.根据海洋卡盾藻的生长曲线,分别收集对数生长期、稳定期、衰亡期的藻细胞进行溶血毒性的测定;采用不同营养元素结构的培养基对CMHK进行培养,对不同培养条件下的藻细胞进行溶血活性...     

高效低温聚磷菌的筛选及特性研究

通过人工模拟自然降温的方式,从A2/O反应器驯化污泥中筛选到低温条件下聚磷效果较好的三株功能菌株P1、P2、P3,经试验得到一种分离聚磷菌效果较好的方法 -稀释混合平板法;分析研究三株菌的聚磷效果、生化特性,测定三株菌的多维生长曲线,研究了温度、pH、微量元素对这三株菌的生长量及除磷率的影响,结果表明,三株菌的生长最适温度均为15℃,适宜的生长和除磷pH为中性偏碱。最后用分子生物学的方法对三株菌进行鉴定,三株菌均属于不动杆菌属的约氏不动杆菌(A cinetobacter Johnson ii)。     

影响凹陷管道安全因素分析

为了分析管道上凹陷对其安全性的影响,以非线性接触模型为基础,应用ABAQUS有限元软件,建立矩形状压头作用于管道的三维模型。通过求解模型,探讨了凹陷深度、凹陷位置、凹陷尺寸、管道内压对管道轴向应变和韧性失效损伤因子的影响。结果表明:管道的轴向应变随着内压的增大而增大,然而内压的存在却对管道韧性失效起到一定的抑制作用。当韧性失效损伤因子D=1时可以通过韧性断裂准则预测其临界失效应变;当凹陷深度超过一定范围内压会使损伤程度增大;当凹陷位置为垂直于管道正上方时,其对管道的轴向应变及韧性失效损伤因子的影响较大;当管道内压一定时,随着凹陷变形量的增加,与凹陷轴向长度相比,凹陷宽度的变化对管道的轴向应变及韧性失效损伤因子程度影响更显著,而增大凹陷长度和宽度均可有效降低其对管道安全性的影响。     

压裂钻孔孔壁破坏行为与注水流量相关性试验研究

为分析流量对水力压裂钻孔起裂特征的影响,开展了不同注水流量水力压裂实验,得到了煤体起裂过程的孔壁压缩应变-水压曲线。结果表明,流量的增大使破裂形态趋于复杂,表现在裂缝的数目及宽度会变多增大,而原煤则更易于沟通原生裂隙;对于无明显节理的配比型煤,随着注水流量增大,孔壁应变速率和起裂压力均增高;对于含明显节理的原煤,孔壁应变速率及起裂压力变化具有一致性,但与流量变化不一致,原煤内部的节理会影响试块起裂行为,降低钻孔内能量积聚速率和煤体破裂强度。研究成果对于揭示钻孔起裂行为具有重要理论意义,为水力压裂实验研究提供了一种新思路。     

蒙特卡洛法计算750kV输电线路绕击跳闸率的研究

利用GDS多功能三轴仪,通过控制土样应变增量比开展了饱和砂土部分排水三轴试验;利用超静孔隙水压力、有效应力路径和应力应变关系三方面的实验结果,研究了饱和砂土的渐近状态特性。研究表明,控制应变增量比为常数进行常规三轴加载时,饱和砂土的有效应力比也趋于某一常数,形成渐近状态,且渐近状态应力比随应变增量比的增大而减小。基于土的剪胀特性给出了渐近状态形成的物理机制,并给出了北京某砂土在部分排水条件下渐近状态应力比的试验结果。     

钢纤维对混凝土疲劳性能增强的研究

钢纤维混凝土是将少量的钢钎维均匀地撒布于混凝土板的上下表面．中间仍为素混凝土。利用了钢钎维的增强性能对板面薄弱部分进行加强。通过梁的弯曲疲劳试验．得到钢钎维混凝土和素混凝土的曲线;进行分析比较．得出钢纤维对混凝土疲劳性能增强机理。     

基于DIC技术获取焊接接头单轴拉伸力学性能

目的 获取异种金属焊接接头局部拉伸力学性能.方法 针对压水堆核电机组蒸汽发生器接管与安全端异种金属焊接接头(Dissimilar metal weld joint,DMWJ,其接管材料为20MND 5低合金钢,安全端为Z2 CND 18.12控氮奥氏体不锈钢,焊缝材料为INCONEL 52镍基合金),采用等直圆棒拉伸试...