Water in oil emulsion droplet size characterization using a pulsed field gradient with diffusion editing (PFG-DE) NMR technique

This paper describes a proton nuclear magnetic resonance (NMR) technique, pulsed field gradient with diffusion editing (PFG-DE), to quantify drop size distributions of brine/crude oil emulsions. The drop size distributions obtained from this technique were compared to results from the traditional pulsed field gradient (PFG) technique. The PFG-DE technique provides both transverse relaxation (T2) and drop size distributions simultaneously. In addition, the PFG-DE technique does not assume a form of the drop size distribution. An algorithm for the selection of the optimal parameters to use in a PFG-DE measurement is described in this paper. The PFG-DE technique is shown to have the ability to resolve drop size distributions when the T2 distribution of the emulsified brine overlaps either the crude oil or the bulk brine T2 distribution. Finally, the PFG-DE technique is shown to have the ability to resolve a bimodal drop size distribution.     

SDAT: analysis of <Superscript>131m</Superscript>Xe with <Superscript>133</Superscript>Xe interference

The Spectral Deconvolution Analysis Tool (SDAT) software was developed at The University of Texas at Austin. SDAT utilizes a standard spectrum technique for the analysis of β–γ coincidence spectra. Testing was performed on the software to compare the standard spectrum analysis technique with a region of interest (ROI) analysis technique. Experimentally produced standard spectra and sample data were produced at the Nuclear Engineering Teaching Laboratory (NETL) TRIGA reactor. The results of the testing showed that the standard spectrum technique had lower errors than the ROI analysis technique for samples with low counting statistics. In contrast, the ROI analysis technique outperformed the standard spectrum technique in high counting statistics samples. It was also shown that the standard spectrum technique benefitted from a compression of the number of channels within the spectra.     

Plasmonic-Based Electrochemical Impedance Imaging of Electrical Activities in Single Cells

Studying electrical activities in cells, such as action potential and its propagation in neurons, requires a sensitive and non-invasive analytical tool that can image local electrical signals with high spatial and temporal resolutions. Here we report a plasmonic-based electrochemical impedance imaging technique to study transient electrical activities in single cells. The technique is based on the conversion of the electrical signal into a plasmonic signal, which is imaged optically without labels. We demonstrate imaging of the fast initiation and propagation of action potential within single neurons, and validate the imaging technique with the traditional patch clamp technique. We anticipate that the plasmonic imaging technique will contribute to the study of electrical activities in various cellular processes.     

Plasmonic‐Based Electrochemical Impedance Imaging of Electrical Activities in Single Cells

Studying electrical activities in cells, such as action potential and its propagation in neurons, requires a sensitive and non‐invasive analytical tool that can image local electrical signals with high spatial and temporal resolutions. Here we report a plasmonic‐based electrochemical impedance imaging technique to study transient electrical activities in single cells. The technique is based on the conversion of the electrical signal into a plasmonic signal, which is imaged optically without labels. We demonstrate imaging of the fast initiation and propagation of action potential within single neurons, and validate the imaging technique with the traditional patch clamp technique. We anticipate that the plasmonic imaging technique will contribute to the study of electrical activities in various cellular processes.     

Simultaneous correlation chromatography,a new technique applied to calibration in high-performance liquid chromatography

Simultaneous correlation chromatography (SCC) is introduced as a technique capable of analyzing several different samples simultaneously on the same chromatographic column. The theoretical basis of the technique is outlined and a computer simulation demonstrates the feasibility of the method. The advantages and potential of the technique are discussed. The technique is applied experimentally in a calibration procedure for high-performance liquid chromatography. During the calibration, unknown sample and calibration standards are processed under the same conditions, resulting in very accurate calibration. Other applications are outlined.     

A novel general and efficient technique for dissociating antigen in circulating immune complexes

Circulating immune complexes (CICs) are produced during the immune response. It is more clinically important to establish a general and efficient CICs dissociation technique for the detection of antigens for CICs other than the detection of free antigens in the serum. Polyethylene glycol (PEG) two‐precipitation separation and glycine‐HCl as a buffer system were employed to develop a general and efficient buffer dissociation technique to separate CICs from serum and dissociate antigens from CICs. The measurement value of new PEG two‐precipitation separation technique was higher than traditional PEG precipitation separation technique. There were slight differences in the dissociation conditions of HCV Core‐IC, HIV P24‐IC, Ins‐IC and TG‐IC as compared to HBsAg‐IC. The detection of antigens in HBsAg‐IC, HCV Core‐IC, HIV P24‐IC, Ins‐IC and TG‐IC with this technique was superior to that with HCl Dissociation, Trypsin Digestion or Immune Complex Transfer technique. PEG two‐precipitation dissociation technique may reduce macromolecular protein and the adhesion of free antigens during the co‐precipitation, which increases the efficiency of separation and precipitation of CICs. This technique also avoids the damage of reagents to antigens, assuring the repeatability, reliability and validity. Thus, this technique is application in samples negative or positive for free antigens.     

微波炉在流动注射体系中的在线应用

微波炉在流动注射体系中的在线应用是近１０年来发展的一项新技术，在样品的在线分解和加速流动注射分析中指示反应速度方面获得广泛应用。本文从仪器技术、结果和应用几个方面概述了从１９８６年以来这项技术的发展。     

Progress of solid-phase microextraction coatings and coating techniques

Solid-phase microextraction (SPME) has been popular as an environmentally friendly sample pretreatment technique to extract a very wide range of analytes. This is partly owing to the development of SPME coatings. One of the key factors affecting the extraction performances, such as the sensitivity, selectivity, and reproducibility, is the properties of the coatings on SPME fibers. This paper classifies the materials used as SPME coatings and introduces some common preparation techniques of SPME coating in detail, such as sol-gel technique, electrochemical polymerization technique, particle direct pasting technique, restricted access matrix SPME technique, and molecularly imprinted SPME technique.     

A new technique for the measurement of the dynamic evolution of surface tension

We develop a novel technique which deduces the surface tension in air of a fluid as a function of surface age, beginning at age zero. The technique utilizes pointwise measurements of perpendicular free surface profiles of a steady oscillating jet corresponding to a discretization interval on the order of 0.1 ms. We implement the technique on constant-surface-tension test fluids (100% ethanol and 15% ethanol/85% water by volume) to demonstrate the extent to which the technique can qualitatively capture that the surface tensions of these fluids are constant in time, and quantitatively produce values of these constants consistent with static measurements. We then implement the technique on jets of two agricultural surfactant mixtures, Triton X-405 and Triton X-100, and quantitatively deduce the decay of surface tension as a function of surfactant concentration.     

热分析联用技术及其在金属材料领域中的应用

热分析联用技术是在热重分析基础上,将多种检测手段并用,准确地研究材料的结构、组成、热反应等特性,从而揭示材料热分解过程本质的技术。在程序升温过程中,利用热分析联用技术对金属材料的质量和热量变化及热分解产物成分等信息进行检测,能更精准地研究金属材料的组成和热分解特性。该文在热重分析法的基础上,着重介绍了其与差热分析、差示扫描量热分析、傅里叶红外光谱分析、质谱分析等分析方法的联用,并以金属材料研究为例,分析了热分析联用技术在金属材料的结构、性能测定等方面的应用,同时展望了热分析联用技术的应用前景。     

Application of the reference-element technique for fast sequential flame atomic-absorption spectrometry

Fast sequential flame atomic-absorption spectrometry (FS-FAAS) is able to measure a sequence of analyte wavelengths in one monochromator scan and so achieves or exceeds the analysis speed of sequential ICP–OES. The requirements and implementation of an FS-FAAS instrument are presented in detail. FS-FAAS is a sequential multi element technique which retains the advantages of conventional FAAS, for example ease of use. While the FS-FAAS technique is an ideal tool for routine determination of elements in the mg L^–1 concentration range, it is still subject to common sources of error such as transport problems and long-term drift. The reference-element technique can be used to correct for these types of common interference; other advantages include correction of some errors which are induced during sample preparation, and improved analytical accuracy and precision. The reference-element technique when utilizing the FS- FAAS technique is described in detail and benefits of the technique will be demonstrated by comparing performance for selected applications, for example a mineral sample and a scrap wood digest.     

Probing polymer surfaces and interfaces using sum frequency generation vibrational spectroscopy - a powerful nonlinear optical technique

Sum frequency generation (SFG) vibrational spectroscopy has been proved to be a powerful technique which substantially impacts on many research areas in surface and interfacial sciences. This paper reviews the recent progress of applying this nonlinear optical technique in the studies of polymer surfaces and interfaces. The theoretical background of SFG is introduced first. Current applications of SFG in polymer science are then described in more detail to demonstrate the significance of this technique. Finally, a short summary is presented on this relatively new but widely applicable spectroscopic technique.     

A single-tilt TEM stereomicroscopy technique for crystalline materials.

A new single-tilt technique for performing TEM stereomicroscopy of strain fields in crystalline materials has been developed. The technique is a weak beam technique that involves changing the value of g and/or s g while tilting across a set of Kikuchi bands. The primary benefit of the technique is it can be used with single-tilt TEM specimen holders including many specialty holders such as in situ straining, heating, and cooling holders. Standard stereo-TEM techniques are almost always limited to holders allowing two degrees of rotational freedom (i.e., double-tilt or tilt/rotation holders). An additional benefit of the new technique is that it eliminates the need to focus with the specimen height control. These advantages make it useful for stereo viewing or for quantitative stereomicroscopy provided necessary consideration is given to errors that may result from the technique.     

羰基化反应的若干开发研究进展

本文介绍了羰基化反应及其特点。指出在我国资源条件下, 开发作为现代化工骨干技术的羰基化反应具有重要的现实与战略意义。报道了国内外羰基化技术研究、开发的若干进展与现状, 对在我国发展羰基化技术提出了建议。     

Atomic absorption spectrometric determination of Cd,Pb, Zn,Cu, Co and Fe in oyster tissue by direct atomization from the solid state using the graphite furnace platform technique

This paper describes a simple and rapid method for direct determination of traces of Cu, Zn, Pb, Co, Fe and Cd in the NBS oyster tissue, SRM No. 1566, by graphite furnace atomic absorption spectrometry. The solid sampling technique has been used and this results in much higher relative sensitivity by avoiding large dilution factors involved in the sample dissolution technique. The solid sampling technique also greatly reduces or eliminates serious risk of introducing contamination and/or loss of analytes involved in sample dissolution. The organic matrix of the oyster tissue is burnt off and removed by using a well-defined selective volatilization technique. Loss of Cd during charring (pyrolysis) stage is prevented by forming a relatively thermally stable compound of cadmium by adding (NH₄₂SO₄ solution to the oyster tissue sample. Also, quantitative data are presented on the effectiveness of the platform technique in removing matrix interferences. The platform technique uses an anisotropic pyrolytic graphite platform which is inserted into a commercial graphite tube.     

Evanescent Wave Light Scattering A Fusion of the Evanescent Wave and Light Scattering Techniques to the Study of Colloids and Polymers Near the Interface

The evanescent wave light scattering technique, which is produced by a fusion of the evanescent wave technique and light scattering technique, is a very powerful and useful tool for investigation of colloidal particles and polymers near the surface and interfaces. We have developed two kinds of evanescent wave light scattering apparatuses. One is the evanescent wave dynamic light scattering (EVDLS) technique and the other is the evanescent wave light scattering microscope (EVLSM). By EVDLS, the diffusion behavior of a colloidal particle near the interface can be extracted quantitatively as a function of the distance from the interface. The diffusion coefficient was smaller than those for particles in bulk, reflecting electrostatic and hydrodynamic interactions. By EVLSM, the interaction potential profile between a colloidal particle and the surface in dispersion can be evaluated directly. EVLSM will play an important role in colloidal interaction studies, especially at a low ionic strength. It is also pointed out that a particle dynamics study is also possible by the EVLSM technique. A new field will be developed in colloid science and polymer science by application of the evanescent wave light scattering technique, i. e. a fusion of the evanescent light and a light scattering techniques.     

A lab-on-a-chip compatible bioaffinity assay method for human alpha-fetoprotein

A new lab-on-a-chip compatible binding assay platform is introduced. The platform combines dry-chemistry bioaffinity reagents and the recently introduced ArcDia TPX binding assay technique. The technique employs polymer microspheres as a solid phase reaction carrier, fluorescently labeled antibody conjugates, and detection of fluorescence emission from the surface of individual microspheres by two-photon excitation fluorescence. Signal response of the technique is independent of the reaction volume, thus the technique is particularly well suited for detection of bioaffinity reactions from miniature volumes. Performance of the new assay platform is studied by means of an immunometric assay of human alpha-fetoprotein (hAFP) in 384-plate format, and the results are compared to those of a corresponding wet-chemistry assay method. The results show that the ArcDia TPX detection technique can be combined with dry-chemistry reagents without compromises in assay performance. The microchip field has so far been characterized with a lack of microchip-compatible detection platforms which would allow cost-effective microchip design and sensitive bioaffinity detection. The presented detection technique is expected to provide a solution for this shortage.     

The rotating particles probe: A new technique to measure interactions between particles and a substrate

We demonstrate a new probing technique to measure physicochemical interactions between particles and a substrate in a fluid. The technique is based on the measurement of field-induced rotation of individual magnetic particles in contact with the substrate. The parallel measurement of many particles with single-particle resolution gives reliable statistics in a short time. Using this technique, the interaction between streptavidin-coated magnetic particles and a glass substrate is measured for various buffer conditions. Increased binding is quantified for increasing ionic strength and decreasing pH. The results are found to be in agreement with calculations of electrostatic interactions. We also apply the technique to study how binding is reduced by blocking the substrate with albumin.     

Electroelution of proteins from bands in gel electrophoresis without gel sectioning for the purpose of protein transfer into mass spectrometry: elements of a new procedure

Electroelution of protein bands from a gel has advantages over the competitive common technique requiring gel sectioning with respect to yield, speed and the potential for computer-controlled application to multicomponent two-dimensional (2-D) gels. The electroelution design for the commercial high-performance gel electrophoresis (HPGE) apparatus represented the most advanced technique to date until the recent discontinuation of its production. The present report serves to summarize the necessary design elements for the purpose of renewing and further developing the electroelution technique. A rudimentary technique is presented by which the electroeluate is collected in a glass tube superimposed on a reversibly stained gel band and connected to an anolyte reservoir. Although the stain used is insufficiently sensitive, the technique allowed for the qualitative verification of its usefulness in the transfer of the electroeluate into mass spectrometry.     

Langmuir monolayers as unique physical models

Physico-chemical processes at air/liquid interfaces are of paramount importance in nature. The Langmuir technique offers the possibility of forming a well-defined monolayer of amphiphilic molecules under study at the air/liquid interface, with a unique control of the area per molecule and other experimental conditions. Despite being a traditional technique in Colloid and Interface science, there is an ever growing interest in Langmuir studies. Herein, recent developing fields of research currently taking advantage of the Langmuir technique are reviewed, comprising the interfacial structure of: water, biomolecules and inorganic/organic hybrids. The good state of the Langmuir technique at present and the foreseeable increase of its usage are discussed.