污泥样品中稀土元素的检测方法研究

取稀土工业园区的污水处理设施和受影响河流的的污泥样品,分别采用三种样品预处理方法(敞开式酸溶法、石墨加热消解和微波消解法)进行对比研究,结果表明:石墨消解法前处理污泥样品后,使用ICP-MS测定其中稀土元素(Y、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu),其方法简便快捷,检出限低,准确度好。     

Mathematical study of hydrocyclone dispersed phase separation in clearing viscoplastic drilling fluids

On the basis of rheodynamic equations, a numerical investigation of the flow structure of a viscoplastic fluid and dispersed phase separation in a hydrocyclone has been carried out. The proposed mathematical model will make it possible to calculate the separation indices and the velocity, pressure, and particle density fields in the apparatus.     

Gas flow-assisted alignment of super long electrospun nanofibers

Electrospinning provides a simple and versatile method for generating ultra thin fibers with diameters ranging from nanometer to micron out of various materials. However, there are still challenges in the alignment of electrospun nanofibers, which is an important step toward the exploitation of these fibers in applications. In this letter, we report a method using the gas flow to assist the alignment of electrospun nanofibers, which can form well-aligned super long polymeric nanofibers over large areas with the length of more than 20 cm. The improved collector is built by coupling a "T"-shaped electrode and a rectangle electrode, and it can make the electrospun nanofiber form a fixed site at the "T"-shaped electrode under the electric field and make it possible to use an assisting gas flow (AGF) to draw the other part of the nanofiber to fly toward the upside of the rectangle electrode and obtain well-aligned long nanofibers. These well-aligned long nanofibers can be further applied easily without disturbing the aligned structure, which is convenient for the measurement and device fabrications.     

GPC separation of polymer samples for MALDI analysis

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is an important technique to characterize the average molecular weights, oligomer repeat units, and end groups of polymer materials. Although MALDI methods have been developed for a broad variety of different synthetic polymers, MALDI continues to struggle with polymer samples having broad polydispersity (PD). We have combined MALDI and gel permeation chromatography (GPC) analyses for broad PD polymer samples with the use of a liquid chromatography (LC) interface. The LC interface uses heated sheath gas and a capillary nozzle to remove most of the mobile phase and deposit the GPC eluants on the precoated matrix on a moving MALDI plate. Our experiments demonstrate that the combination of GPC-LC interface-MALDI can aid in the characterization of broad PD samples, the verification of the presence of low-intensity, high-mass oligomers, and the detection of minor series in polymer samples.     

残留油脂在空分设备运行中的危害性及其检测方法

简介残留油脂对空分设备运行造成的安全隐患以及空分设备中油脂残留量的标准要求,重点介绍油脂残留量定量检测中的油分浓度测定法及其检测实例,最后提出为减小测量误差而采取的措施。     

Real-time potentiometric detection of bacteria in complex samples

Detecting and identifying pathogen bacteria is essential to ensure quality at all stages of the food chain and to diagnose and control microbial infections. Traditional detection methods, including those based on cell culturing, are tedious and time-consuming, and their further application in real samples generally implies more complex pretreatment steps. Even though state-of-the-art techniques for detecting microorganisms enable the quantification of very low concentrations of bacteria, to date it has been difficult to obtain successful results in real samples in a simple, reliable, and rapid manner. In this Article, we demonstrate that the label-free detection and identification of living bacteria in real samples can be carried out in a couple of minutes and in a direct, simple, and selective way at concentration levels as low as 6 colony forming units/mL (CFU) in complex matrices such as milk or 26 CFU/mL in apple juice where the pretreatment step of samples is extremely easy. We chose Escherichia coli ( E. coli ) CECT 675 cells as a model organism as a nonpathogenic surrogate for pathogenic E. coli O157:H7 to test the effectiveness of a potentiometric aptamer-based biosensor. This biosensor uses single-walled carbon nanotubes (SWCNT) as excellent ion-to-electron transducers and covalently immobilized aptamers as biorecognition elements. The selective aptamer-target interaction significantly changes the electrical potential, thus allowing for both interspecies and interstrain selectivity and enabling the direct detection of the target. This technique is therefore a powerful tool for the immediate identification and detection of microorganisms. We demonstrate the highly selective detection of living bacteria with an immediate linear response of up to 10(4) CFU/mL. The biosensor can be easily built and used, is regenerated without difficulty, and can be used at least five times with no loss in the minimum amount of detected bacteria.     

Measurement of the physical properties of dispersed weakly magnetic samples to estimate their stability

A method of estimating the stability of the physical properties of dispersed weakly magnetic samples is developed for the purpose of optimizing the adjustment of an eddy-current detector. Translated from Izmeritel'naya Tekhnika, No. 9, pp. 59–62, September, 2008.     

Microfluidic separation and gateable fraction collection for mass-limited samples

Integrating multiple analytical processes into microfluidic devices is an important research area required for a variety of microchip-based analyses. A microfluidic system is described that achieves preparative separations by intelligent fraction collection of attomole quantities of sample. The device consists of a main microfluidic channel used to perform electrophoresis, which is interconnected at 90 degrees to two vertically displaced channels via a nanocapillary array membrane. The membrane interconnect contains nanometer-diameter pores that provide fluidic communication between the channels. Sample injection and analyte collection are controlled by application of an electrical bias between the microfluidic channels across the nanocapillary array. After the separation, the automated transfer of the FITC-labeled Arg, Gln, and Gly bands occurs; a fluorescence detector located at the separation/collection channel interconnect is used to generate a triggering signal that initiates suitable voltages to allow near-quantitative transfer of analyte from the separation channel to the second fluidic layer. The ability to achieve such sample manipulations from mass-limited samples enables a variety of postseparation processing events.     

Limit of detection determination for censored samples

The problem of setting the limit of detection is considered for censored samples and heterogeneous errors. After formal definitions of the critical level and of the method detection limit, we obtain simplified maximum likelihood-type estimators. The estimation problem of the truncation parameter and its uncertainty are reviewed. Upper confidence bounds for the limit of detection are derived and some simulation results are given.     

Concentration and size separation of DNA samples at liquid-liquid interfaces

This report introduces a new analytical concept utilizing the mass transfer resistance of a liquid-liquid interface to concentrate and separate DNA samples. DNA molecules can be electrophoretically accumulated at a liquid-liquid interface of an aqueous two-phase system (ATPS) of poly(ethylene glycol) (PEG) and dextran, two polymers that form two immiscible phases in aqueous electrolyte solutions. The detachment of DNA from the interface into the other phase can be triggered by increasing the applied electric field. We experimentally study the size dependence of the detachment process for a broad spectrum of DNA fragments. In a regime where the coiling of the chains does not play a significant role, the process shows a linear dependence on the diffusion coefficient, with shorter DNA chains detaching at lower electric field strengths than larger ones. The concept may enable novel separation protocols for preparative and analytical purposes.     

Some results of an investigation of the kinetics of separation and mixing of dispersed materials

This paper gives the results of an investigation of the kinetics of separation and mixing of dispersed materials due to vibration or a flow of liquid or gas in application to mineral enrichment and screen separation of grain products and other materials.     

Complex samples cyanide detection with immobilized corrinoids

Colorimetric solid phase with spatially separated extraction and detection zones as a rapid, effective and economic method for the optical detection of cyanide in complex samples is described. The system is seven times more sensitive for the optical detection of cyanide than the same class of chemical sensors used under homogeneous conditions. The application of the method in the detection of (i) endogenous cyanide in colored plant samples and of (ii) hydrogen cyanide in tobacco smoke is shown. The optical detection of multiple anions within a single sample has been demonstrated in principle for the detection of both CN(-) and SCN(-). Immobilized aquacyano-corrinoids and immobilized vitamin B12 are applied as chemical sensors, and cyanide is qualitatively identified by the violet color (λ(max) = 583 nm) of the corresponding dicyano-complex. Quantitative determinations with diffuse reflectance spectroscopy (DRUV-vis) are possible in the linear range up to 0.2 mg/L with a LOD of 1 μg/L. Alkyl-modified silica particles are employed for immobilization of the indicator on the surface of the solid phase (detection zone), and for removal of colored hydrophobic interferents (extraction zone).     

Nanostructure enabled extracellular vesicles separation and detection

Extracellular vesicles(EVs) have recently attracted significant research attention owing to their important biological functions, including cell-to-cell communication. EVs are a type of membrane vesicles that are secreted into the extracellular space by most types of cells. Several biological biomolecules found in EVs, such as proteins, microRNA, and DNA, are closely related to the pathogenesis of human malignancies,making EVs valuable biomarkers for disease diagnosis, treatment, and prognosis. ...     

基于局部几何投影法的信号分离技术

文章介绍了局部几何投影法的主要技术思路,提出新的覆盖修正方法和信号分离效果度量。应用该方法对理想混沌信号与调幅正弦脉冲进行分离以及对实测的湖底混响与调幅正弦脉冲进行分离。结果表明：在一定条件下,局部几何投影法对于理想混沌信号与脉冲信号的分离很有效;对实际的混响信号与某些脉冲信号的分离效果也非常好,但是该方法对于混响信号与调幅正弦脉冲信号的分离在两者中心频率相接近的时候效果不理想。     

Application of photoassisted electrochemical detection to explosive-containing environmental samples

High-performance liquid chromatography (HPLC) with ultraviolet (UV) absorbance and photoassisted electrochemical detection (PAED) is applied to the determination of explosives in groundwater and soil samples. On-line, solid-phase extraction minimizes sample pretreatment, enabling direct analysis of groundwater samples and soil extracts. Soils are extracted using pressurized fluid extraction, which is compared to the Environmental Protection Agency (EPA) sonication method. Limits of detection for explosives in the matrixes of interest are equivalent or superior (i.e., <10 parts-per-trillion for HMX) to those achieved using the EPA method 8330. HPLC-UV-PAED is also shown here to be more broadly applicable, as it is capable of determining nitro compounds of interest (e.g., nitroglycerin) that have poor UV chromophores. Additional selectivity of amine-substituted nitroaromatic explosives is achieved by using a photochemical reactor with a 366-nm wavelength lamp. By coupling reversed-phase columns of different selectivities together, baseline resolution of all 14 standard explosives is demonstrated.     

Mass exchange in isotope separation by the distillation method

We investigate the turbulent flow of a gas in a packed column; taking account of this flow, we obtain a general analytic expression for the height of the equilibrium stage in the separation of isotopes by the distillation method.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 1, pp. 117–124, July, 1982.     

断裂韧性测试中的载荷分离法及应用

针对无法直接获得载荷(P)-加载线位移(load line displacement,LLD)对应的塑性功导致无法直接完成基于直通型紧凑拉伸试样(front face compact tension,FFCT)试样材料断裂韧性测试的问题,该文基于迭代理念将适用于台阶型试样(load line compact tension,LLCT)的规则化法推广应用于FFCT试样,得到基于FFCT试样评估延性材料断裂韧性的可行方法.结合汽轮机转子钢和迭代方法,验证新方法准确性,最后将迭代方法应用于核反应堆材料A508-Ⅲ钢的J阻力曲线测试中,有助于解决基于1/2FFCT试样获取断裂韧性的难题.