Dielectrophoretic field-flow method for separating particle populations in a chip with asymmetric electrodes

This paper presents a field-flow method for separating particle populations in a dielectrophoretic (DEP) chip with asymmetric electrodes under continuous flow. The structure of the DEP device (with one thick electrode that defines the walls of the microfluidic channel and one thin electrode), as well as the fabrication and characterization of the device, was previously described. A characteristic of this structure is that it generates an increased gradient of electric field in the vertical plane that can levitate the particles experiencing negative DEP. The separation method consists of trapping one population to the bottom of the microfluidic channel using positive DEP, while the other population that exhibits negative DEP is levitated and flowed out. Viable and nonviable yeast cells were used for testing of the separation method.     

广西2016年土壤风险点位土壤风干样品制备及其保存

文章主要介绍了土壤样品制备前的准备、土壤样品制备过程、土壤样品的保存、土壤制备过程质量控制.统一规范操作,确保数据的准确性和可比性.     

Microfluidic sample preparation for respiratory virus detection: A review

Techniques used to prepare clinical samples have been perfected for use in diagnostic testing in a variety of clinical situations, e.g., to extract, concentrate, and purify respiratory virus particles. These techniques offer a high level of purity and concentration of target samples but require significant equipment and highly trained personnel to conduct, which is difficult to achieve in resource-limited environments where rapid testing and diagnostics are crucial for proper handling of respiratory viruses. Microfluidics has popularly been utilized toward rapid virus detection in resource-limited environments, where most devices focused on detection rather than sample preparation. Initial microfluidic prototypes have been hindered by their reliance on several off-chip preprocessing steps and external laboratory equipment. Recently, sample preparation methods have also been incorporated into microfluidics to conduct the virus detection in an all-in-one, automated manner. Extraction, concentration, and purification of viruses have been demonstrated in smaller volumes of samples and reagents, with no need for specialized training or complex machinery. Recent devices show the ability to function independently and efficiently to provide rapid, automated sample preparation as well as the detection of viral samples with high efficiency. In this review, methods of microfluidic sample preparation for the isolation and purification of viral samples are discussed, limitations of current systems are summarized, and potential advances are identified.     

A self-contained polymeric cartridge for automated biological sample preparation

Sample preparation is one of the most crucial processes for nucleic acids based disease diagnosis. Several steps are required for nucleic acids extraction, impurity washes, and DNA/RNA elution. Careful sample preparation is vital to the obtaining of reliable diagnosis, especially with low copies of pathogens and cells. This paper describes a low-cost, disposable lab cartridge for automatic sample preparation, which is capable of handling flexible sample volumes of 10 μl to 1 ml. This plastic cartridge contains all the necessary reagents for pathogen and cell lysis, DNA/RNA extraction, impurity washes, DNA/RNA elution and waste processing in a completely sealed cartridge. The entire sample preparation processes are automatically conducted within the cartridge on a desktop unit using a pneumatic fluid manipulation approach. Reagents transportation is achieved with a combination of push and pull forces (with compressed air and vacuum, respectively), which are connected to the pneumatic inlets at the bottom of the cartridge. These pneumatic forces are regulated by pinch valve manifold and two pneumatic syringe pumps within the desktop unit. The performance of this pneumatic reagent delivery method was examined. We have demonstrated the capability of the on-cartridge RNA extraction and cancer-specific gene amplification from 10 copies of MCF-7 breast cancer cells. The on-cartridge DNA recovery efficiency was 54-63%, which was comparable to or better than the conventional manual approach using silica spin column. The lab cartridge would be suitable for integration with lab-chip real-time polymerase chain reaction devices in providing a portable system for decentralized disease diagnosis.     

Influence of microorganisms on the environmental fate of radionuclides

Microorganisms have a significant influence on the environmental fate of radionuclides in aquatic and terrestrial ecosystems with a multiplicity of physico-chemical and biological mechanisms effecting changes in mobility and speciation. Physico-chemical mechanisms of removal include association with extracellular materials, metabolites and cell walls which are features of living and dead organisms. In living cells, some physico-chemical processes are reversible, influenced by metabolism and changing environmental conditions. Metabolism-dependent mechanisms of radionuclide immobilization include sulphide precipitation, transport and intracellular compartmentation and/or sequestration by proteins and peptides. In addition, chemical reduction to less soluble forms can result in immobilization. Microbial processes involved in radionuclide solubilization include autotrophic and heterotrophic leaching, and complexation by siderophores and other metabolites. Such mechanisms are important components of biogeochemical cycles for radionuclides and should be considered in any analyses of environmental radionuclide contamination. In addition, several microorganism-based biotechnologies are receiving interest as potential treatment methods.     

Pushbutton-activated microfluidic cartridge as a user-friendly sample preparation tool for diagnostics

Microfluidic technologies have several advantages in sample preparation for diagnostics but suffer from the need for an external operation system that hampers user-friendliness. To overcome this limitation in microfluidic technologies, a number of user-friendly methods utilizing capillary force, degassed poly(dimethylsiloxane), pushbutton-driven pressure, a syringe, or a pipette have been reported. Among these methods, the pushbutton-driven, pressure-based method has a great potential to be widely used as a user-friendly sample preparation tool for point-of-care testing or portable diagnostics. In this Perspective, we focus on the pushbutton-activated microfluidic technologies toward a user-friendly sample preparation tool. The working principle and recent advances in pushbutton-activated microfluidic technologies are briefly reviewed, and future perspectives for wide application are discussed in terms of integration with the signal analysis system, user-dependent variation, and universal and facile use.     

环保物联网技术在环境监测中的应用

文章介绍环保物联网的概念及应用的总体架构,论述了环保物联网在中国环保领域的发展与实践。对环保物联网在桂林市环境监测中的发展现状进行分析,并指出环保物联网在环境监测中应用存在的问题,提出推动环保物联网在桂林市环境监测建设和发展的建议。     

西藏环境监测的发展方向探讨

本文阐述了环境监测学的研究内容、发展历程及未来方向。     

Dielectrophoretic microfluidic device for the continuous sorting of Escherichia coli from blood cells

Microfluidic diagnostic devices promise faster disease identification by purifying and concentrating low-abundance analytes from a flowing sample. The diagnosis of sepsis, a whole body inflammatory response often caused by microbial infections of the blood, is a model system for pursuing the advantages of microfluidic devices over traditional diagnostic protocols. Traditional sepsis diagnoses require large blood samples and several days to culture and identify the low concentration microbial agent. During these long delays while culturing, the physician has little or no actionable information to treat this acute illness. We designed a microfluidic chip using dielectrophoresis to sort and concentrate the target microbe from a flowing blood sample. This design was optimized using the applicable electrokinetic and hydrodynamic theories. We quantify the sorting efficiency of this device using growth-based assays which show 30% of injected microbes are recovered viable, consistent with the electroporation of target cells by the dielectrophoretic cell sorters. Finally, the results illustrate the device is capable of a five-fold larger microbe concentration in the target analyte stream compared to the waste stream at a continuous sample flow rate of 35 μl∕h.     

Dielectrophoretic capture voltage spectrum for measurement of dielectric properties and separation of cancer cells

In this paper, a new dielectrophoresis (DEP) method based on capture voltage spectrum is proposed for measuring dielectric properties of biological cells. The capture voltage spectrum can be obtained from the balance of dielectrophoretic force and Stokes drag force acting on the cell in a microfluidic device with fluid flow and strip electrodes. The method was demonstrated with the measurement of dielectric properties of human colon cancer cells (HT-29 cells). From the capture voltage spectrum, the real part of Clausius-Mossotti factor of HT-29 cells for different frequencies of applied electric field was obtained. The dielectric properties of cell interior and plasma membrane were then estimated by using single-shell dielectric model. The cell interior permittivity and conductivity were found to be insensitive to changes in the conductivity of the medium in which the cells are suspended, but the measured permittivity and conductivity of cell membrane were found to increase with the increase of medium conductivity. In addition, the measurement of capture voltage spectrum was found to be useful in providing the optimum operating conditions for separating HT-29 cells from other cells (such as red blood cells) using dielectrophoresis.     

浅析环保设施工程中的验收监测

叙述了建设项目竣工环境保护验收检查与监测的内容.指出,建设项目环境保护设施竣工验收监测检查工作,要坚持全面考察、重点突出和区别对待.     

Comparison of protein precipitation methods for sample preparation prior to proteomic analysis of Chinese hamster ovary cell homogenates

BackgroundChinese hamster ovary (CHO) cells are the workhorse for obtaining recombinant proteins. Proteomic studies of these cells intend to understand cell biology and obtain more productive and robust cell lines for therapeutic protein production in the pharmaceutical industry. Because of the great importance of precipitation methods for the processing of samples in proteomics, the acetone, methanol-chloroform (M/C), and trichloroacetic acid (TCA)-acetone protocols were compared for CHO cells in terms of protein recovery, band pattern resolution, and presence on SDS-PAGE.ResultsHigher recovery and similar band profile with cellular homogenates were obtained using acetone precipitation with ultrasonic bath cycles (104.18 ± 2.67%) or NaOH addition (103.12 ± 5.74%), compared to the other two protocols tested. TCA-acetone precipitates were difficult to solubilize, which negatively influenced recovery percentage (77.91 ± 8.79%) and band presence. M/C with ultrasonic homogenization showed an intermediate recovery between the other two protocols (94.22 ± 4.86%) without affecting protein pattern on SDS-PAGE. These precipitation methods affected the recovery of low MW proteins (< 15 kDa).ConclusionsThese results help in the processing of samples of CHO cells for their proteomic study by means of an easily accessible, fast protocol, with an almost complete recovery of cellular proteins and the capture of the original complexity of the cellular composition. Acetone protocol could be incorporated to sample-preparation workflows in a straightforward manner and can probably be applied to other mammalian cell lines as well.How to cite: Pérez-Rodriguez S, Ramírez OT, Trujillo-Roldán MA et al. Comparison of protein precipitation methods for sample preparation prior to proteomic analysis of Chinese hamster ovary cell homogenates. Electron J Biotechnol 2020;48. https://doi.org/10.1016/j.ejbt.2020.09.006.     

广西2016年土壤风险点位土壤样品采集及质量保证

土壤样品的采集对于土壤环境质量监侧数据结果的准确性起着决定性的作用,土壤样品采集的质量保证和质量控制是科学、准确地荻取有代表性、典型性的土壤样品的保障.文章从采样前的物品准备、采样人员、采样工作要求、现场采样、样品流转、质量控制等方面论述了广西2016年土壤风险点位土壤样品采集的质量保证和质量控制.     

Dielectrophoretic spectra of translational velocity and critical frequency for a spheroid in traveling electric field

An analysis has been made of the dielectrophoretic (DEP) forces acting on a spheroidal particle in a traveling alternating electric field. The traveling field can be generated by application of alternating current signals to an octapair electrode array arranged in phase quadrature sequence. The frequency dependent force can be resolved into two orthogonal forces that are determined by the real and the imaginary parts of the Clausius–Mossotti factor. The former is determined by the gradient in the electric field and directs the particle either toward or away from the tip of the electrodes in the electrode array. The force determined by the imaginary component is in a direction along the track of the octapair interdigitated electrode array. The DEP forces are related to the dielectric properties of the particle. Experiments were conducted to determine the DEP forces in such an electrode arrangement using yeast cells (Saccharomyces cervisiate TISTR 5088) with media of various conductivities. Experimental data are presented for both viable and nonviable cells. The dielectric properties so obtained were similar to those previously reported in literature using other DEP techniques.     

M-stock: Efficient stock monitoring for mobile users

The emergence of sophisticated and powerful mobile devices with impressive computing capabilities and storage capacity paves the way for an era of advanced mobile-based applications. Monitoring of time-critical data, process control, and security are possible candidate applications. In this work we propose a stock monitoring system that utilizes mobile phones. The system was designed to provide an alternative to costly GPRS connections for stock market traders. The system grants real-time monitoring of stock information through a user-friendly and easy to use GUI with plenty of useful features. The system was implemented by combining various Java technologies, specifically J2ME and J2EE. It was tested using the Dubai Financial Market with favorable results.     

生物质炭与土壤可持续管理:从土壤问题到生物质产业

南美洲古老农业文明孕育的暗色肥沃土壤引发了全球生物质炭研究热潮。将农业生产过程中产生的有机废弃物经过低温热裂解技术转化为生物质炭并施用于农田土壤中,是一种新的土壤可持续管理途径,且服务于生物质废弃物治理与生态农业。我国生物质炭工业化生产技术及炭基肥制备与施用技术已经形成,土壤增碳与农业增产、减肥、增效潜力显著。大规模生物质炭工业化生产的推广催生了一个新兴的科技领域——生物质科技与工程。该科技服务于中国巨大的生物质废弃物治理和土壤改良、化肥减量及绿色农业等需求,这一学科领域尚待系统整合和提升。文章提出,研究生物质炭的有机质组分、结构、性质与功能的表征与有机质-矿物-微生物相互作用的基础研究是未来土壤可持续管理中的重要研究方向。这些问题将揭示生物质炭对于农业生命的系统健康及绿色农业的巨大价值,也进一步彰显了土壤学服务于中国农业可持续管理与生物质产业融合的巨大价值。     

A hybrid dielectrophoretic system for trapping of microorganisms from water

Assessment of the microbial safety of water resources is among the most critical issues in global water safety. As the current detection methods have limitations such as high cost and long process time, new detection techniques have transpired among which microfluidics is the most attractive alternative. Here, we show a novel hybrid dielectrophoretic (DEP) system to separate and detect two common waterborne pathogens, Escherichia coli (E. coli), a bacterium, and Cryptosporidium parvum (C. parvum), a protozoan parasite, from water. The hybrid DEP system integrates a chemical surface coating with a microfluidic device containing inter-digitated microelectrodes to impart positive dielectrophoresis for enhanced trapping of the cells. Trimethoxy(3,3,3-trifluoropropyl) silane, (3-aminopropyl)triethoxysilane, and polydiallyl dimethyl ammonium chloride (p-DADMAC) were used as surface coatings. Static cell adhesion tests showed that among these coatings, the p-DADMAC-coated glass surface provided the most effective cell adhesion for both the pathogens. This was attributed to the positively charged p-DADMAC-coated surface interacting electrostatically with the negatively charged cells suspended in water leading to increased cell trapping efficiency. The trapping efficiency of E. coli and C. parvum increased from 29.0% and 61.3% in an uncoated DEP system to 51.9% and 82.2% in the hybrid DEP system, respectively. The hybrid system improved the cell trapping by encouraging the formation of cell pearl-chaining. The increment in trapping efficiency in the hybrid DEP system was achieved at an optimal frequency of 1 MHz and voltage of 2.5 V_pp for C. parvum and 2 V_pp for E. coli, the latter is lower than 2.5 V_pp and 7 V_pp, respectively, utilized for obtaining similar efficiency in an uncoated DEP system.     

利益相关者环保导向与企业生态创新——高管环保意识的调节作用

以江浙沪144家制造和有形服务企业为样本,从制度理论和高阶理论的整合视角考察了利益相关者环保导向对生态创新的影响以及高管环保意识的权变效应。主要结论包括:第一,政府环保导向对生态产品创新具有显著正向影响,与生态工艺创新呈倒U型的关系;客户环保导向对生态管理创新具有显著正向影响,与生态产品创新呈倒U型的关系;竞争者环保导向对生态管理创新、生态工艺创新和生态产品创新均具有显著正向影响。第二,不同高管环保意识对不同利益相关者环保导向与不同生态创新的之间调节效应不同。