线性电压扫描法测量硅的体产生寿命和表面产生速度的研究

本文采用Rabbani的产生区宽度模型,导出了描述线性电压扫描作用下MOS电容器的电容—时间瞬态特性的微分方程,通过积分这一微分方程,得到了描述线性电压扫描作用的MOS电容器的电容—时间瞬态特性方程.依据这一方程,提出了一种确定体产生寿命和表面产生速度的计算方法.

表面产生负氢离子引出MCC算法设计

本文深入研究负氢离子输运及引出物理机理,理论分析了交换电荷反应及库仑碰撞过程,并设计了相应数值计算模块.在此基础上,采用有限差分法计算负氢离子所受洛伦兹力,运用蒙特卡罗碰撞方法处理负氢离子与其他粒子间的碰撞,成功研制了表面产生负氢离子输运及引出的全三维MCC算法,结合国外热门离子源JAEA10A离子源进行模拟验证,结果显示:随着过滤磁场增大,引出离子数越大,离子源空间生存离子总数越小;当过滤磁场较小时,气压越大引出离子数越多,当过滤磁场较大时,气压越小引出离子数越多.

生物表面活性剂产生菌的筛选及其对土壤重金属铅的活化作用

结合油平板和血平板方法从重金属8处复合污染的土壤样品中筛选出15株能产生物表面活性剂的细菌菌株，其中J119菌株不仅具有良好的产生物表面活性剂的性能，而且能在含铅、镉浓度分别为100—200mg·L^-1、25—100mg·L^-1的平板中生长．同时对J119菌株所产的生物表面活性剂与3种不同类型化学合成表面活性剂活化土壤中铅的效能进行了比较．结果表明，在400mg·kg^-1铅污染土壤中，J119菌株发酵液与化学合成表面活性剂活化土壤中铅的效果相当；与对照相比，在800mg·kg^-1铅污染土壤中，J119菌株发酵液处理使土壤中有效性铅的浓度增加51．1％，而3种化学合成表面活性剂CTAB、SDS、Tween-80处理土壤中有效态铅浓度仅比对照增加28．7％、26．2％和16．0％另外，J119菌株产生的生物表面活性剂与供试3种化学合成表面活性剂对土壤中铅的活化作用之间存在显著差异．

生物表面活性剂产生菌的筛选及特性研究

从石油污染的土壤中分离出3株生物表面活性剂产生菌,经鉴定菌株31#为假单胞菌属,菌株37#和47#均为芽孢杆菌属。以液体石蜡为唯一碳源液态培养所筛菌株,测定发酵液的菌体密度、pH、表面张力及细胞疏水性。结果表明,菌株31#、37#及47#在发酵过程中的发酵液表面张力最低值分别为49.47、58.00和56.04 mN/m;pH均在7.0～7.5;菌株均出现二次生长;细胞疏水性最大值分别为3.09%、1.49%和1.66%。菌株31#、37#及47#所产的生物表面活性剂经硅胶薄层层析方法鉴定为鼠李糖脂。

堆肥微生物产生的生物表面活性剂的提纯表征

从堆肥中筛选产生生物表面活性剂的菌种,然后对筛选得到的菌种于适宜条件下进行发酵培养,得到生物表面活性剂.同时对生物表面活性剂发酵液进行萃取、柱层析等一系列的分离提纯,得到较纯的生物表面活性剂及一种较好的提纯生物表面活性剂的方法,然后采用液质联用对提纯的生物表面活性剂进行表征,结果表明该堆肥中产生生物表面活性剂的主要菌种为铜绿假单胞菌,其产生的生物表面活性剂为鼠李糖脂.

滨海海底边界层对底栖微体化石仿真模拟的影响

计算流体力学CFD(computational fluid dynamics)近年来在古生物学研究中已有大量应用。该方法在研究生物化石的个体形态、器官功能,以及其与生存环境之间的关系方面具有重要意义。目前古生物领域的CFD仿真对象多为厘米级别体型的生物,而对于毫米级别大小的微体生物的仿真则相对较少。区别于厘米级别的宏体生物,底栖型微体生物的生活环境局限于海床上方垂直高度较小的区域,受海底黏性边界层低流速区域的影响更为明显,因而在设置这类化石仿真的水流环境时应当考虑对于边界层流域水体流速以及海床表面地理环境的还原。本文基于随机表面生成的方法,构建了不平坦的滨海海床表面模型,并模拟了水流在海底边界层附近受海床表面地形影响的流动状态;基于获得的仿真流速数据,我们仿真了寒武纪微型底栖刺细胞动物化石Quadrapyrgite在起伏的海床表面环境中四个不同位置的受水流阻力情况。仿真结果显示,近海床表面处的水体流动可形成明显的低流速区域,且低流速区域的厚度随着入口速度增大而变薄。在起伏表面的凹凸区域中,凸起地带的迎水面形成的低流速区域较薄,流速变化较快;而在凸起地带背水面以及凹陷地带形成的低流速区域较厚,流速较缓且易形成涡旋。流速的差异体现在不同位置的Quadrapyrgite的受阻力大小不同上,其差值可达数倍到数十倍。这种量级的受阻力差值可以在毫米级到厘米级尺度上塑造、影响底栖型生物的分布甚至其自身的摄食行为。本文的研究为CFD方法模拟底栖微型化石的生存环境提供了更加深入的思路和方法。

发酵培养法筛选堆肥中产表面活性物质的菌种

微生物在城市生活垃圾堆肥中起着重要的作用 ,而某些微生物在一定条件下产生的生物表面活性剂有望改善堆肥的微环境 ,提高堆肥的效率。从不同温度的堆肥过程中 (45℃和 55℃ )筛选产生物表面活性剂的细菌 ,生物表面活性剂的产生通过测定其发酵液的张力值来判断。实验结果表明 ,堆肥过程中的确存在产生物表面活性剂的细菌 ,枯草芽孢杆菌是其主要菌之一。实验通过一系列培养条件的优化 ,使所筛选到的细菌产生活性较强。

一株既产表面活性剂又高效降解石油烃菌株的鉴定及降解效果

在修复石油烃污染的环境时,多采用表面活性剂增强修复效果,而一些微生物既能降解石油烃,又能代谢分泌表面活性剂,从而促进油的乳化,提高油的分散程度,增大菌株和油珠的接触面积,提高其对石油烃的降解,增强修复效果。该研究从石油污染土壤中筛选出一株既产生物表面活性剂又高效降解石油烃的菌株B-6。通过观察形态特征、生理生化试验及16S r DNA序列分析,对菌株进行鉴定。并研究了菌株产生物表面活性剂及降解石油烃的特性。实验结果表明,B-6初步鉴定为假单胞菌属(Pseudomonas sp.)。菌株B-6的发酵液经粗提后,得到黄褐色粘稠状生物表面活性剂粗品,其产量为2.19 g·L^(-1)。红外光谱分析表明,菌株B-6在代谢过程中能产生糖脂类生物表面活性物质。该菌株用于水中石油烃的降解,石油烃初始浓度为2 000 mg·L^(-1),120 r·min^(-1)、30℃下振荡培养5 d后,菌株对石油烃的降解率达99.13%。

烃降解菌WJ-1及其生物表面活性剂特性研究

从蒙古林油田水样筛选得到一株能以烃类为唯一碳源、高产表面活性剂的烃降解菌WJ-1,经16SrDNA初步鉴定为铜绿假单胞菌Pseudomonas aeruginosa。该菌株以大豆油为碳源的培养基发酵7天,发酵液表面张力降到25.586mN/m,排油圈直径增大到11.8cm。薄层色谱分析表明所产表面活性剂主要有鼠李糖脂、蛋白类和脂类,蒽酮法测得96小时发酵液中鼠李糖脂含量最高,为55g/L;从发酵液提取的棕黄色生物表面活性剂(粗品),其表观临界胶束浓度为20mg/L;以不同黏度的4种原油作为碳源培养7天,原油平均降解率为52%。在渗透率0.4μm2的物理模型上,以1PV的0.6%WJ-1菌液、0.6g/L的聚合物溶液、0.6%WJ-1菌液+0.6g/L的聚合物溶液分别驱替水驱残余油,采收率分别提高6.56%、9.08%、23.08%,表明该菌可用于微生物采油。

生物表面活性剂在石油环保中运用价值

根据《中国21世纪发展议程》发展需要,生物表面活性剂因其对人们生产生活污染少等特点,已备受人们的关注。化学合成的表面活性剂由于其原材料来源、价格、产品性能和环境污染等方面的问题,其使用受到一定的限制。为了解决上述问题,人们寄希望于应用生物技术来生产活性高、性能优、环境友好的表面活性剂。这样的表面活性剂,一方面。

负氢离子引出PIC-MCC数值模拟算法

首先介绍了负氢离子产生机理,阐述了三维蒙特卡罗碰撞处理(MCC)方法,结合经典电磁与粒子互作用模拟(PIC)算法,成功研制了全三维PIC-MCC算法,并采用该算法对串联双腔多峰离子源中负氢离子(H^-)引出过程进行了数值模拟。模拟结果显示:表面产生H^-引出概率为27.8%,远大于体积产生H^-引出概率;体积产生H^-的产生位置距离引出电极越远,引出效率越低;随着离子源放电室气压的增大,体积和表面H^-引出效率都将减小。

大功率负离子源铯注入对负离子产额影响的实验研究

铯注入可显著降低射频负离子源等离子体电极(Plasma Grid,PG)金属表面逸出功,促进H−离子的表面产生,是提高射频负离子源H−离子产额的有效手段。依托强流射频负离子源综合测试平台,以H−离子表面产生机制、铯注入作用机制为理论基础,以H−离子引出电流、电子引出电流及铯852 nm特征谱线相对强度等数据为依据;通过控制PG板温度和铯注入速率,本实验探究在铯注入条件下,PG板温度和铯注入速率对射频负离子源H−离子产额的影响作用。实验结果表明:铯注入可有效提高H−离子产额,且在当前实验条件下,PG温度在180~200℃范围时,H−离子转换速率最大;在铯注入温度为250℃/270℃时,约162 min后,H−离子转换速率达到动态平衡。

Surface species of chalcopyrite during bioleaching by moderately thermophilic bacteria

X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.

一株高效生物表面活性剂产生菌的分离、鉴定及培养条件的优化

以市政污水处理厂剩余活性污泥作为菌种来源,经过培养分离、筛选,得到一株高效生物表面活性剂产生菌X1A-2.经形态学与16SrDNA鉴定,X1A-2菌株属于戈登氏菌属.菌株X1A-2产生物表面活性剂的环境影响因素研究结果表明:菌株在发酵培养14h后达到稳定状态,发酵液表面张力降低至33.0mN/m;在较大的培养条件范围内,发酵液的表面张力均可显著降低;石油烃类碳源的存在对其产生物表面活性剂的影响甚微.在模拟石油污染的最优培养条件下,菌株能够长期保持活性,所产生物表面活性剂可使以石油为碳源的发酵液表面张力保持在35mN/m以下.研究结果表明,X1A-2是一株高效生物表面活性剂产生菌,在实际海洋石油污染的生物修复方面具有很好的应用前景.

Heat transfer and nanofluid flow over a porous plate with radiation and slip boundary conditions

Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanoparticles type,suction or injection,the heat generation or absorption,the Eckert number,thermal and velocity slip parameters,and radiation on the velocity and temperature fields on the flow and heat transfer over a porous flat plate.Four different types of nanoparticles including metal nanoparticles (Cu),metal oxide nanoparticles (Al2O3) and carbon-based nanomaterials (MWCNTs and SWCNTs) which were dispersed in the water (as based fluid) are studied.The governing equations are converted into the ordinary differential equations using similarity solution and solved numerically by the RKF45 algorithm.The results of the simulations showed a contradiction with the results of other researchers who expressed that using nanoparticles with higher thermal conductivity and volume fraction led to increasing heat transfer rate in nanofluids;this study proves that,in some cases,boosting the volume fraction of nanoparticles has a potential to decrease the heat transfer rate due to significant changes in values of some parameters including radiation,heat generation,and viscous dissipation.

Reuse of waste frying oil for production of rhamnolipids using Pseudomonas aeruginosa zju.u1M

In this work,rhamnolipid production was investigated using waste frying oil as the sole carbon source. By culture in shaking flasks,a naturally isolated strain synthesized rhamnolipid at concentration of 12.47 g/L and its mutant after treatment by UV light increased this productivity to 24.61 g/L. Fermentation was also conducted in a 50 L bioreactor and the productivity reached over 20 g/L. Hence,with a stable and high productive mutant strain,it could be feasible to reuse waste frying oil for rhamnolipid production on industrial scale.

Stability and Drag Reduction in Transient Channel Flow of Fibre Suspension

Drag reduction features in the transition regime of channel flow with fibre suspension were analyzed in terms of the linear stability theory. The modified stability equation was obtained based on the slender-body theory and natural closure approximation. Results of the stability analysis show attenuating effects of fibre additives to the flow instability. For the cases leading to transition, drag reduction rate increases with the characteristic parameter H of fibres. The mechanism of drag reduction by fibres is revealed through the variation of velocity profile and the decrease of wall shear stress. The theoretical results are qualitatively consistent with some typical experiments.

Research on forced gas draining from coal seams by surface well drilling

Surface drilling was performed at the Luling Coal Mine,in Huaibei,to shorten the period required for gas draining.The experimental study was designed to reduce the cost of gas control by efficiently draining gas from the upper protected layer.The structural arraignment and technical principles of pressure relief via surface drilling are discussed.Results from the trial showed that gas drained from the surface system over a period of 10 months.The total amount of collected gas was 248.4 million m^3.The gas draining occurred in three stages：a growth period;a period of maximum gas production;and an attenuation period.The period of maximum gas production lasted for 4 months.During this time the methane concentration ranged from 60%to 90%and the average draining rate was 10.6 m^3/min.Combined with other methods of draining it was possible to drain 70.6%of the gas from middle coal seam groups.The amount of residual gas dropped to 5.2 m^3/ton,and the pressure of the residual gas fell to 0.53 MPa, thereby eliminating the outburst danger in the middle coal seam groups.The factors affecting pressure relief gas draining by surface drilling were analysed.

Multiscale Characterization of Automotive Surface Coating Formation for Sustainable Manufacturing

Automotive surface coating manufacturing is one of the most sophisticated and expensive steps in automotive assembly. This step involves generating multiple thin layers of polymeric coatings on the vehicle surface through paint spray and curing in a multistage, dynamically changing environment. Traditionally, the quality control is solely post-process inspection based, and process operational adjustment is only experience based, thus the manufacturing may not be （highly） sustainable. In this article, a multiscale system modeling and analysis methodology is introduced for achieving a sustainable application of polymeric materials through paint spray and film curing in automotive surface coating manufacturing. By this methodology, the correlations among paint material, application processes and coating performance can be identified. The model-based analysis allows a comprehensive and deep study of the dynamic behaviors of the material, process, and product in a wide spectrum of length and time. Case studies illustrate the efficacy of the methodology for sustainable manufacturing.

Hybrid Surface Mesh Adaptation for Climate Modeling

Solution-driven mesh adaptation is becoming quite popular for spatial error control in the numerical simulation of complex computational physics applications,such as climate modeling.Typically,spatial adaptation is achieved by element subdivision (h adaptation) with a primary goal of resolving the local length scales of interest.A sec- ond,less-popular method of spatial adaptivity is called'mesh motion'(r adaptation); the smooth repositioning of mesh node points aimed at resizing existing elements to capture the local length scales.This paper proposes an adaptation method based on a combination of both element subdivision and node point repositioning (rh adaptation). By combining these two methods using the notion of a mobility function,the proposed approach seeks to increase the flexibility and extensibility of mesh motion algorithms while providing a somewhat smoother transition between refined regions than is pro- duced by element subdivision alone.Further,in an attempt to support the requirements of a very general class of climate simulation applications,the proposed method is de- signed to accommodate unstructured,polygonal mesh topologies in addition to the most popular mesh types.