Effects of non-Newtonian power law rheology on mass transport of a neutral solute for electro-osmotic flow in a porous microtube

Mass transport of a neutral solute for a power law fluid in a porous microtube under electro-osmotic flow regime is characterized in this study. Combined electro-osmotic and pressure driven flow is conducted herein. An analytical solution of concentration profile within mass transfer boundary layer is derived from the first principle. The solute transport through the porous wall is also coupled with the electro-osmotic flow to predict the solute concentration in the permeate stream. The effects of non-Newtonian rheology and the operating conditions on the permeation rate and permeate solute concentration are analyzed in detail. Both cases of assisting (electro-osmotic and poiseulle flow are in same direction) and opposing flow (the individual flows are in opposite direction) cases are taken care of. Enhancement of Sherwood due to electro-osmotic flow for a non-porous conduit is also quantified. Effects if non-Newtonian rheology on Sherwood number enhancement are observed.     

Bond graphs for thermal energy transport and entropy flow

The transport of thermal energy in thermodynamics is described as the product of entropy flow and of the absolute temperature, in analogy to the volume flow and pressure in oil hydraulics and to electric charge flow (= current) and voltage in electronics. Bond graphs are shown to be especially suitable to describe the splitting of applied thermal energy into internal energy and external mechanical work. Transformers and the 0- and 1-junctions of Paynter can illustrate various entropy flow processes, including Carnot engines and heat exchangers. Entropy flow in heat conduction is distinguished from entropy convection, or transport by moving mass, where the entropy/temperature characteristic or equation of state is important. Irreversibilities are represented by impedance transformers reducing temperature and increasing entropy flow but conserving power.     

Isolation of target DNA using synergistic magnetic bead transport and electrokinetic flow

The advent and dissemination of next-generation sequencing (NGS) technologies such as Illumina''s sequencing platforms has brought forth vast reductions in the cost, time, and technical difficulties associated with DNA and RNA sequencing. Despite this trend, the workflow required to generate nucleic acid libraries for sequencing remains time-consuming and laborious. The following research proposes a method for simplifying and streamlining this process by replacing the manual washing steps of the common magnetic bead-based cleanup with a novel microfluidic method by integrating magnetic separation and electrokinetic purification (MSEP). Requiring no pumps, pipette mixing, vortexing, or centrifugation, MSEP relies on selective adsorption of target DNA onto the magnetic beads with subsequent transport of beads through a microchannel undergoing an antiparallel electroosmotic flow. The synergetic flow conditions were optimized using a simple electrohydrodynamic flow model. This work demonstrates that MSEP is as effective in eliminating adapter-dimers from the post-ligation library mix as the manual method while also greatly reducing the hands-on time and amount of pipetting required. Although MSEP has been applied specifically toward NGS library preparation at this time, it has the potential to be adapted and employed for any bead-based separation scheme, namely, solid phase extraction, sequence-specific hybridization, and immunoprecipitation on a microscale.     

广谱型水土保持人才培养的方法

我国是世界上水土流失最严重的国家之一,严重威胁粮食安全和生态安全.为了提高水土保持学的教学教果,增强学生的实践能力和环境保护理念,基于多年的教学实践,初步从教学理念、教学内容的选择、课堂的教学设计和教学方法四方面探讨了水土保持学的教学过程,以便使水土保持理念更深入地被学生接受,真正培养出社会需求的广谱应用型人才.     

水泥厂开发建设工程水土保持方案编制中的设计要点

开发建设项目建设过程中获得最大经济利益的同时,势必给原有的生态环境带来严重破坏和影响。本文以辽宁省某水泥厂为例,根据水土流失特点,分区设计了水泥厂项目区内各项水土流失防治措施。经治理,项目区内生态效益,经济效益度社会效益得到很大提高。     

台吉营风力发电场新建工程水土流失预测

在说明台吉营风力发电场新建工程水土流失预测所需基本参数的基础上,采用类比与数学模型相结合的方法对工程扰动原地貌及损坏水土保持设施面积、项目弃渣量、可能造成的水土流失量进行了预测。     

鸡冠山镁石矿业项目区水土流失预测

在说明水土流失预测所需基本参数的基础上,采用类比与数学模型相结合的方法对工程扰动原地貌及损坏水土保持设施面积、项目弃渣量、可能造成的水土流失量进行了预测,并对水土流失可能造成的危害做了分析。     

公路水土保持与绿化措施

公路的迅速发展对经济的发展起到了巨大地促进作用,由此所引起的水土流失却给环境带来严重的威胁。如何预防及杜绝水土流失是公路建设中需要解决的一项重要工作,对水土保持措施的研究有重要的意义。     

黄土高原水土保持工程措施的生态系统服务

黄土高原严重的水土流失是黄河泥沙的主要来源。自1950s以来大规模实施的水土保持工程建设是黄土高原水土流失治理的重要举措,在减少入黄泥沙方面做出了巨大贡献。水土保持工程措施通过直接或间接地作用于坡面、沟道的水文过程和物质迁移过程等,改变了水资源和土壤资源的时空分配格局,在土壤保持、粮食供给、水文调节等方面发挥了重要作用,对黄河流域生态安全具有重要贡献。本文系统综述了黄土高原水土保持工程措施的发展演变,阐述了水土保持工程措施对水土过程的作用机制及对关键生态系统服务的贡献,探讨了新形势下黄土高原水土保持工程措施建设面临的问题、挑战。在此基础上提出今后黄土高原水土保持工程措施应加强维护和管理,提升应对极端气候事件和自然灾害的能力,面向国家生态文明建设和区域社会经济发展需求,统筹工程措施与植被措施,进行科学的设计与合理的时空配置,以维护黄土高原及黄河流域生态安全、维持和提升区域生态系统服务功能及社会经济效益。     

西部生态环境演变规律与水土资源可持续利用研究

实施西部大开发战略,加快中西部地区发展,对于加快我国现代化建设的历史进程,维护国家安全和社会稳定,实现中华民族的伟大复兴,具有重要的现实意义和深远的历史意义。积极参与国家西部大开发战略的实施,是中国科学院广大科技人员神圣的责任,也是知识创新工程试点工作的一项重要内容。为此,我院以为西部大开发提供科学依据和技术支撑为基本出发点,于2000年组织实施了“西部行动计划”,先后启动了7个知识创新工程重大项目,涉及农业、生态环境、新药研制及产业化发展等。经过两年多的研究,各项目均取得阶段性进展,为西部地区的科技事业和社会经济可持续发展做出了贡献,在学术界产生了较大影响,得到了国家领导人、国家相关主管部门和地方政府的充分肯定,也受到了社会各界的广泛关注。为使广大读者及时了解“西部行动计划”各项目的进展情况,本刊与“西部行动计划领导小组办公室”合作,从本期起开辟专栏进行连续报道。     

伊犁河谷土壤水力侵蚀的时空变化研究

为定量化评估多因子对伊犁河谷土壤侵蚀的影响及其联合效应,本文应用修正土壤流失方程,估算近30年来（1985-2000年和2000-2015两个时段）伊犁河谷土壤水力侵蚀的时空变化,分析降雨、植被盖度和土地利用各因子对土壤侵蚀变化的作用。结果表明：研究区总体上土壤侵蚀状况较轻,以微度侵蚀为主,面积占比达到83.99%,强度侵蚀等级以上的面积占比仅为2.25%,零星分布于南、北、中天山的局部地区;严重土壤侵蚀主要分布在低覆盖度的草地。对比两个时段,研究区的土壤侵蚀呈总体改善但局部恶化的趋势,轻度侵蚀等级以上的面积都显著减少。从1985-2000年到2000-2015年,伊犁河谷的降雨侵蚀力明显增加,而植被覆盖与管理因子和水土保持因子的数值则显著减少,耦合三者的时空变化,其对伊犁河谷土壤侵蚀的影响以负效应为主。