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81.
E Gaertner EH Zeren MV Fleming TV Colby WD Travis 《Canadian Metallurgical Quarterly》1996,20(1):36-45
Trichoderma reesei endoglucanase I (EGI) was used as a reporter enzyme for screening mutagenized yeast strains for increased ability to produce protein. Sixteen haploid Saccharomyces cerevisiae strains, transformed with a yeast multicopy vector pALK222, containing the EGI cDNA under the ADH1 promoter, produced EGI activity of 10(-5)-10(-4) g/l. On the average 93% of the total activity was secreted into the culture medium. Two strains with opposite mating types were mutagenized, and several mutants were isolated possessing up to 45-fold higher EGI activity. The best mutants were remutagenized and a second-generation mutant, strain 2804, with an additional twofold increase in EGI activity was selected. The mutant strain 2804 grew more slowly and reached a lower final cell density than the parental strain. In the selective minimal medium, the 2804 strain produced 40 mg/l immunoreactive EGI protein, but only 2% was active enzyme. In the rich medium the secreted EGI enzyme stayed active, but without selection pressure the EGI production ceased after 2 days of cultivation, when the strain 2804 had produced 10 mg/l of EGI. A sevenfold difference was found between the parental and the 2804 strain in their total EGI production relative to cell density. The difference in favour of the mutant strain was also detected on the mRNA level. The 2804 mutant was found to be more active than the parental strain also in the production of T. reesei cellulases, cellobiohydrolase I, and cellobiohydrolase II. 相似文献
82.
83.
S. Zor M. Zeren H. Özkazanç E. Karakulak 《Protection of Metals and Physical Chemistry of Surfaces》2012,48(5):568-571
Aluminium and its alloys are the most used non-ferrous metals because of their satisfactory properties. Especially the corrosion resistant in different mediums is the most important reason for this. The corrosion resistance of the aluminium comes from the oxide layer on the surface. Different alloying elements have different effect on corrosion behaviour of the aluminium alloys. In this study effect of different amount of titanium addition on corrosion behaviour of Al-Si eutectic alloys was investigated. 相似文献
84.
A Sahin D Eiley ER Goldfischer KG Stravodimos S Zeren HD Isenberg AD Smith 《Canadian Metallurgical Quarterly》1998,52(3):411-5; discussion 415-6
OBJECTIVES: We investigated the in vitro nonthermal effects of microwaves delivered from Prostatron 2.0 on Escherichia coli and Enterobacter cloacae. METHODS: The fingers of powder-free, sterile gloves were ligated, and bacterial solutions were transferred into the remaining area of the glove. The gloves were then sealed using silk ligatures. One set of gloves was subjected to the microwave treatment while another set was placed in a temperature-matched waterbath to act as control samples. The gloves containing the treatment group were taped around the probe, at the site where microwave energy exits the probe. During the treatment period, the temperatures from the urethral probe and the rectal probe were carefully monitored. RESULTS: The mean (+/-SD) energy delivered was 46.6 +/- 9.5 kJ (range 30.0 to 59.5) for the 10 trials on E. coli and colony counts in the experimental microwaved gloves decreased significantly compared with control samples (5.26 +/- 4.5 x 10(5) versus 10.16 +/- 9.3 x 10(5) CFU/mL, P = 0.02). For the experiments on E. cloacae the mean (+/-SD) energy applied was 38.5 +/- 12.5 kJ, and a significant decrease in colony counts of microwaved samples was also observed compared with controls (11.04 +/- 4.8 x 10(5) versus 20.08 +/- 10.1 x 10(5) CFU/mL, P = 0.004). CONCLUSIONS: Microwave energy, delivered from Prostatron 2.0, independent of heat production has an in vitro bactericidal effect on laboratory-cultured E. coli and E. cloacae. 相似文献
85.
86.
87.
Tong YuQi Cheng BingJun Miao YuanQing Zhou Bin Zhu XingHong Yang YanYan Liu Ji Gou XiaoChen Zhang YiTeng Wang JinDong Li Lei Magnes Werner Lammegger Roland Pollinger Andreas Zeren Zhima Shen XuHui 《中国科学:技术科学(英文版)》2021,64(10):2328-2336
Science China Technological Sciences - High precision magnetometer (HPM) is a magnetic field detection payload onboard China Seismo-Electromagnetic Satellite (CSES), including two fluxgate... 相似文献
88.
Finite element modeling the influence of edge roundness on the stress and temperature fields induced by high-speed machining 总被引:1,自引:1,他引:0
Tuğrul Özel Erol Zeren 《The International Journal of Advanced Manufacturing Technology》2007,35(3-4):255-267
High-speed machining (HSM) may produce parts at high production rates with substantially higher fatigue strengths and increased
subsurface micro-hardness and plastic deformation, mostly due to the ploughing of the round cutting tool edge associated with
induced stresses, and can have far more superior surface properties than surfaces generated by grinding and polishing. Cutting
edge roundness may induce stress and temperature fields on the machined subsurface and influence the finished surface properties,
as well as tool life. In this paper, a finite element method (FEM) modeling approach with arbitrary Lagrangian Eulerian (ALE)
fully coupled thermal-stress analysis is employed. In order to realistically simulate HSM using edge design tools, an FEM
model for orthogonal cutting is designed, and solution techniques such as adaptive meshing and explicit dynamics are performed.
A detailed friction modeling at the tool–chip and tool–work interfaces is also carried out. Work material flow around the
round edge cutting tool is successfully simulated without implementing a chip separation criterion and without the use of
a remeshing scheme. The FEM modeling of the stresses and the resultant surface properties induced by round edge cutting tools
is performed for the HSM of AISI 4340 steel. Once FEM simulations are complete for different edge radii and depths of cut,
the tool is unloaded and the stresses are relieved. Predicted stress fields are compared with experimentally measured residual
stresses obtained from the literature. The results indicate that the round edge design tools influence the stress and temperature
fields greatly. An optimization scheme can be developed to identify the most desirable edge design by using the finite element
analysis (FEA) scheme presented in this work. 相似文献
89.
90.
基于连续小波变换的瞬态位移干涉仪信号处理 总被引:4,自引:1,他引:3
提出一种连续小波变换(CWT)用于频率急剧变化的瞬态位移干涉仪信号处理的方法.连续小波变换利用对不同频率具有不同分辨本领的特性,对信号进行时频分析,计算出信号频率,进而恢复出信号的速度.当在可变时间窗口宽度内小波的中心频率和信号局部频率相等或接近时,小波变换系数幅值最大,据此能判断出信号的频率.用连续小波变换方法对计算机模拟的化移干涉信号进行处理,恢复的速度相对误差在3%,从爆轰实验的光纤位移干涉仪信号中也能够准确地恢复出物体的速度历史. 相似文献