光合细菌菌数测定数学模型的构建

通过同一浓度的光合细菌菌液在不同波长吸收值的测定,确定322nm为光合细菌的最大吸收波长;在波长322nm下测定不同浓度菌液的光密度值,与双层平板法测数结果相对应,建立OD值和菌数之间的线性关系,推导出直线回归方程,应用此直线回归方程,测定光合细菌的菌数,具有简便快速准确的特点。     

Study of dislocation structures near fatigue cracks using electron channelling contrast imaging technique (ECCI)

The fatigue of copper single crystals, orientated for single slip, has been studied using electron channelling contrast imaging in a scanning electron microscope. With the incident beam set at the Bragg condition, changes in the backscattered electron intensity occur as the beam is scanned over dislocations that cause a local tilting of the diffraction planes. This technique allows the evolution of dislocation structures over large areas to be followed through different stages of the fatigue life. Furthermore, it enables direct imaging of dislocation configurations at crack tips. The technique is compared with transmission electron microscopy and electron backscatter diffraction in its application to fatigue studies.     

光合生物制氢过程中系统温度变化实验研究

以高效产氢细菌群为实验用菌种,采用单因子试验方法,主要研究光合菌群在不同条件下生长制氢过程中由于放热所引起系统温度的变化规律。结果表明:在不同的产氢条件下系统温度随着产氢时间的延长均有明显的变化规律,即光合生物制氢过程中系统温度均有不同幅度的升高。初始温度、接种量和光照强度对系统温度变化有显著影响,从其对温度变化影响看,光合制氢过程中选用初始温度30℃、光照强度2000lux、接种量40%较适宜。     

Comparative value of phosphate sources on the immobilization of lead, and leaching of lead and phosphorus in lead contaminated soils

The mobility and bioavailability of lead (Pb) in soils can be mitigated by its immobilization using both soluble and insoluble phosphate (P) compounds. The effectiveness of insoluble P sources on Pb immobilization depends on their rate of dissolution which can be enhanced by phosphate solubilizing bacteria (PSB). In this study, the effect of soluble (potassium dihydrogen phosphate) and insoluble (rock phosphate in the presence and absence of PSB) P compounds on the immobilization of Pb, and leaching of Pb and P was examined using both naturally contaminated (SR soil: NH₄NO₃ extractable Pb: 28.7 mg/kg, pH: 5.88, organic matter: 0.7%) and Pb spiked (AH soil: NH₄NO₃ extractable Pb: 42.7 mg/kg, pH: 5.23, organic matter: 10.9%) soils. Phosphate compounds were added at the rate of 200 mg P/kg and 800 mg P/kg for SR and AH soils, respectively. Soluble P treatment immobilized 80% and 57% of Pb in SR and AH soils, respectively. Insoluble rock phosphate immobilized 40% and 9% of Pb without PSB, and 60% and 17% with PSB in SR and AH soils, respectively. Lead leaching was the lowest when soils were amended with rock phosphate in the presence of PSB, which reduced Pb leaching by 36% for SR soil and 18% for AH soil compared to the control. The leaching of Pb increased when the soils were amended with soluble P because soluble P treatment increased dissolved organic carbon (DOC) concentration of soil, thereby increasing Pb mobility. Soluble P treatment significantly increased P leaching and 9% of total added P was leached from low P retaining AH soil. The optimum level of P amendment is a critical issue when soluble P is used as a Pb immobilizing agent because of eutrophication resulting from excessive P leaching to surface and ground water. While the soluble P compound was effective in the immobilization of Pb, it resulted in P leaching which increased with increasing levels of P addition. However, rock phosphate amendment with PSB achieved the immobilization of Pb with a minimum effect on both Pb and P leaching.     

Bubble behavior and photo-hydrogen production performance of photosynthetic bacteria in microchannel photobioreactor

A transparent microchannel photobioreactor was manufactured to visualize the colony formation of photosynthetic bacteria (PSB), Rhodopseudomonas palustris CQK 01, as well as the biogas bubble behavior within the microstructure. The results showed that the formation of PSB colony in the interior of microchannels can be divided into four stages: bacteria absorption, bacteria reproduction, morphological transformation and colony formation. It was founded that the microchannel vents immobilized by PSB colony was the favorable sites for the emergence of biogas bubbles. In this work, the effects of substrate concentration and flow rate of the influent solution as well as illumination wavelength and intensity on the photo-hydrogen production performance of the bioreactor were also investigated. The microchannel photobioreactor exhibited a maximal hydrogen production rate of 1.48 mmol/g cell dry weight/h, maximal hydrogen yield of 0.91 mol H₂/mol glucose in all tests at an optimal inlet medium flow rate of 2.8 ml/h and substrate concentration of 50 mmol/l. In addition, photobioreactor showed a highest performance of hydrogen production and substrate consumption at 590 nm illumination wavelength and 5000 lx illumination intensity.     

Matlab电力系统模块中非线性电源的实现方法

Matlab在电力系统仿真中的应用越来越广泛,为电力系统分析带来了极大的方便。给出了利用电力系统模块（PSB）工具箱来实现非线性电源的方法,可以方便地实现各种要求的非线性电源,拓宽了PSB的适用范围。实例仿真结果表明,该方法分析正确,使用便捷,在实际仿真过程中是切实可行的。     

Simulink/PSB在《电路》课程教学中的应用

介绍了Matlab/Simulink工具箱及工具箱中与电路分析计算有关的三个常用库集,结合《电路》课程中含受控源直流稳态电路、一阶动态电路和含受控源正弦交流稳态电路等实例,详细介绍了利用Simulink/PSB建立电路模型,进而分析和计算电路各参数的具体步骤,并总结了一些使用技巧。教学实践证明了应用Simulink/PSB辅助《电路》课程教学的有效性。同时,也为基于计算机辅助分析和设计的《电路》及其它电类课程的教学改革提供了积极的探索。     

预应力混凝土用螺纹钢筋LF炉精炼工艺实践

预应力混凝土用螺纹钢筋简称精轧螺纹钢筋,因具有高强度、高精度、施工便捷而著称,结合广阔的市场前景,石横特钢决定在二炼钢开发屈服强度不低于830 MPa的PSB830级精轧螺纹钢筋。由于该钢种属于高Si低Mn钢种,且Mn/Si低（0.44～0.80）,不利于脱氧合金化操作及连铸浇铸,通过对LF炉精炼工艺的实践,不仅实现了化学成分的精准控制,钢材批次之间性能差异控制在30 MPa以内,而且钢水纯净度达到了目标要求,有效保证了连铸浇铸质量。     

高密度脉冲电流对Cu单晶体驻留滑移带的影响

对含驻留滑移带（ＰＳＢ）的「１２３」取向的疲劳Ｃｕ单晶体,进行了高密度脉冲电流处理,结果表明,高密度脉冲电流处理产生的热压应力改善了ＰＳＢ－基体界面的应力集中状态,使驻留滑移带局部消失,理论计算同时表明,高密度脉冲电流处理能提高Ｃｕ单晶疲劳寿命。     

PSB785精轧螺纹钢控冷轧制工艺实践

为使PSB785精轧螺纹钢筋强度与塑性相匹配,采用以下工艺:(1)钢坯加热出炉温度为960～1 020℃,开轧温度为970℃;(2)轧件进精轧机温度为850～890℃,钢筋的终轧温度为930～1 000℃,自回火温度为680～700℃;(3)上冷床温度为560～600℃。采用设计工艺生产的25,32 mm PSB785精轧螺纹钢筋的抗拉强度为1 021～1 055MPa,延伸率为8.5%～9.6%,金相组织为珠光体+铁素体,晶粒度为9.0～9.5级,穿水层为回火索氏体,穿水层深度为1.24～1.46 mm,符合GB/T 20065—2006《预应力混凝土用螺纹钢筋》,可满足用户的使用要求。