Measurement of the mechanocaloric effect in rubber

An apparatus for measurement of mechanocaloric effect in rubber has been constructed and tested by measuring the thermal response of three rubber materials to mechanical strain. The results obtained were satisfactory. Detailed measurement has been performed on these materials. The entropy changes that accompany elongation were calculated from the experimental results and compared with those derived from literature data and statistical theory of the macromolecular chain. A dissipative effect was found to accompany the rapid deformation of rubber and attributed to viscoelastic irreversibility. An experimental procedure to eliminate this effect was identified. The apparatus, assembled with the readily available components, will be a useful device for introducing the entropy concept in thermodynamics courses.     

疲劳内耗仪的控制微机的更新及功能开发

介绍了对中法合作研制的疲劳内耗仪微机控制部分的改进，采用的ＩＢＭ－３８６，改进了控制及实验数据处理的方式，并扩展了仪器的功能。     

一种用于大容量逆流色谱制备的立式多层螺旋管行星式离心机

Owing to no complications caused by solid supports, such as adsorptive sample loss and deactivation, tailing of solute peaks, and contamination, countercurrent chromatography (CCC) has been an area of intense research since the first introduction of CCC in 1970,[1] and various apparatus and broad applications have been advanced[2,3]. For these developments, the type-J synchronous planet centrifuge has received considerable attention, which relies not only on its relatively simple mechanic design, but also on its high partition efficiency and short elution time caused by mixing and settling for the efficient chromatographic separations. In the past, however, almost all of type-J centrifuges rotated slowly were disposed horizontally due to the original design and some experiments that gravis plays an important role at a low rotary speed as similar to type-V rotating multilayer helical tube in unit gravity[4-9]. In fact,we discovered that the upright apparatus holds more retention of stationary phase than the horiziontal aparatus when large standard tubings were used as mutilayer coil column and the aparatus was operated under same contions. We report here a new coil planet centrifuge with four upright cylindrical columns for large scale countercurrent chromatographic preparation. The design principle and apparatus of UCCC is as samilar to type-J multilayer coil planet centrifuge. Four uptight cylindrical column holders are symmetrically arranged around the centrifuge axis as similar to the type-J HSCCC with three horizontal multilayer coils connected in series[8] . A series of experiments indicat that upright CCC has many advantages over the horizontal CCC when using a large-bore tube as multilayer coil column for large scale countercurrent chromatographic separation.Upright CCC provide a versatile countercurrent chromatographic method for large-scale preparation from very crude sample. It has good preparative capacity and flexible suitability to various sample and two-phase system.The present apparatus not only can be operated at a high speed as similar as commonly used HSCCC for the system having short settling time and but also can be run at a low speed for the system having relative long settling time. Because of automatical control and seal-free flow through device, the uptight CCC apparatus may be readily scaled up to industrial preparation.     

Home-made temperature-control unit for the Waters Quanta 4000 capillary electrophoresis system

A home-made temperature control unit has been developed for a commercial capillary electrophoresis apparatus, the Waters Quanta 4000. The effect of the unit on the absolute migration times and peak areas of nine β-blockers is described. It was found that this homemade temperature control unit considerably (≥ 100 %) improved the repeatability of the separation.     

Phase Behavior and Morphology of Poly(Methyl Methacrylate)/Poly(α‐Methyl Styrene‐co‐Acrylonitrile) Blends Under Quiescent and Shear Flow

The kinetics of spinodal decomposition (SD) for the binary blend poly(methyl methacrylate), PMMA, and Poly(α‐methylstyrene‐co‐acrylonitrile), PαMSAN, with 31 wt% AN content (LCST‐type phase diagram) has been thoroughly studied using a time‐resolved light scattering technique. The early stage SD was dominated by a diffusion process and can be well described within the framework of the linearized Cahn‐Hilliard theory. The spinodal temperature could be evaluated from the analysis of the early stage SD based on the Cahn theory. In addition, viscoelastic properties of this system have been systematically investigated at temperatures below and above the LCST phase diagram. The linear viscoelastic properties of the blends were found to be greatly changed by phase separation in the two‐phase regime. This change in the linear viscoelastic properties attributed to an additional contribution of concentration fluctuations to the material functions at the phase separation temperatures. The phase diagram of the blends was also estimated rheologically through the dynamic temperature ramps of G′, G″ and η*. Furthermore, the phase behavior and morphology of this system has been studied under different shear rates using simple shear apparatus and transmission electron microscopy (TEM), respectively.     

Development of an automated dual‐mode supercritical fluid chromatography and reversed‐phase liquid chromatography mass‐directed purification system for small‐molecule drug discovery

We report the development of a dual‐mode mass‐directed supercritical fluid chromatography and reversed‐phase liquid chromatography purification system. The addition of a third pump allows for flexible mobile phase control between the two techniques, and enables operation of either chromatography mode within minutes by activation of a set of switching valves on a single system. Software control, fluidic pathways, interface to the mass spectrometer, and fraction collection have been modified for compatibility between both separation methods. The conditioning solvent and tuning parameters for the mass spectrometer were adjusted to achieve an ideal signal trace in either mode with good linearity (r² > 0.970) over a range of concentrations and minimal noise for accurate peak detection and isolation. The registration success rate is 90% and overall sample recovery for either technique is 80?90%. Combining two orthogonal separation and purification modes in one single system has improved the purification throughput of complex mixtures and has been a valuable, cost‐saving tool in our laboratory.     

Rheo-optical properties of polyethylene films in the nonlinear viscoelastic region

A new apparatus was designed to investigate the dynamic viscoelastic properties of solid polymer materials in the nonlinear viscoelastic region. The apparatus was combined with a birefringence apparatus in such a way that birefringence could be measured simultaneously with stress under oscillatory deformation. The nonlinear viscoelastic behavior of bulk-crystallized high-density polyethylene films was examined. Nonlinearity of mechanical properties became evident around 30°C, while optical properties became markedly nonlinear around 50°C. The nonlinearity of viscoelastic properties changes very little when the films are swollen with tetrachloroethane. It is proposed that disruption of lamellae to crystallites in the drawing process is one of the most important causes of the nonlinear behavior of high-density polyethylene films.     

A density-based segmentation for 3D images,an application for X-ray micro-tomography

Density-based spatial clustering of applications with noise (DBSCAN) is an unsupervised classification algorithm which has been widely used in many areas with its simplicity and its ability to deal with hidden clusters of different sizes and shapes and with noise. However, the computational issue of the distance table and the non-stability in detecting the boundaries of adjacent clusters limit the application of the original algorithm to large datasets such as images. In this paper, the DBSCAN algorithm was revised and improved for image clustering and segmentation. The proposed clustering algorithm presents two major advantages over the original one. Firstly, the revised DBSCAN algorithm made it applicable for large 3D image dataset (often with millions of pixels) by using the coordinate system of the image data. Secondly, the revised algorithm solved the non-stability issue of boundary detection in the original DBSCAN. For broader applications, the image dataset can be ordinary 3D images or in general, it can also be a classification result of other type of image data e.g. a multivariate image.     

Requirements and tests for HPLC apparatus and methods in pharmaceutical quality control

Summary One possible method has been demonstrated for pharmaceutical quality control which is not restricted to this field and fulfils and documents the prerequisites for reliable, accurate and precise HPLC analysis. This includes validation which shows that the method is able in principle to fulfil the requirements, the apparatus test which shows that the apparatus generally works correctly and precisely and the system suitability test which shows that the method provides accurate and precise results on this apparatus and with this column for the analysis in question when other non-equipment and non-method-induced errors are excluded.     

Trace analysis of BTEX compounds in water with a membrane interfaced ion mobility spectrometer

A tubular silicone membrane interface has been developed for trace detection of benzene, toluene, ethyl benzene, and xylene (BTEX) compounds in water with a portable ion mobility spectrometer. Effects of flow rate, membrane length and stirring conditions on the IMS signals have been systematically investigated. Besides conventional dynamic mode operation, static mode sampling has been demonstrated for the first time and high sensitivities were achieved by sampling of BTEX contaminated water with static mode operation. A toluene concentration of 0.101 mg l(-1) in purified water, corresponding to a headspace concentration of 2.75 (mug m(-3)), was determined by static mode sampling. Headspace sampling without the membrane interface could not detect toluene at this concentration. This method has high sensitivity for trace concentrations of gasoline components in river water with a response time of several seconds. The apparatus developed is portable and can be used for sensitive detection of organic contaminants in water, with improved performance compared to conventional modes of IMS sampling.     

A modified orsat apparatus for analysis of purified coke-oven gas

With the usual Orsat apparatus ethane in coke-oven gas cannot be determined.The value reported as methane is the sum of methane and ethane.Some modifications have been carried out based on the ascertained conditions for determining the ethane content.With the modified apparatus it is possible to determine the ethane without appreciable increase of the duration of the analysis.The accuracy of the determination of ethane is 0.1 to 0.2 per cent by volume.     

An economic approach for construction of a multiplexed capillary electrophoresis system

We describe in this report an economic approach to construct a multiplexed capillary electrophoresis (CE) system with optic-fiber UV detection. To demonstrate the feasibility of this approach, a seven-lane CE setup is built. The system has a background noise of ∼10⁻⁵ absorbance unit, a limit of detection of 3-4 μM for uracil at 254 nm, and a linear dynamic range of 2.5 orders of magnitude. The apparatus consists of three major components: a UV light source, a photodiode array (PDA) and optical module assembly, and a computer. Compared to the recently reported 96-lane capillary electrophoresis system with UV-vis absorbance detection, the cost of goods is reduced by more than 10-fold, and the noise level is improved by 2 to 3 folds. Parallel CE separations of a protein mixture have been performed on this apparatus, and reproducible and high resolution separation results have been obtained. Detailed construction and characterization of the system have also been discussed.     

RAPID AND SENSITIVE OPTICAL ROTATION MEASUREMENT: KINETICS OF CONFORMATIONAL CHANGE OF RHODOPSIN INTERMEDIATE

A rapid and sensitive optical rotation (OR) measurement system using laser light has been developed to meet the demands of flash-photolysis experiments. The optimal OR resolution of the apparatus is 0.3mdeg with 10 μs time constant with single shot. The OR resolution could be easily improved less than 0.1 mdeg with accumulation of data by a kinetic processor. Applications are briefly described for the study of transient conformational change of photochemical intermediates of octopus rhodopsin following a blue light flash.     

The Wickbold combustion method for the determination of mercury under statistical aspects

The combination of the Wickbold combustion apparatus with a mercury/hydride atomic absorption spectrometer for the routine determination of mercury is investigated. A flow injection system is used to introduce the solution from the decomposition into the spectrometer. The data obtained are treated by several statistical tests which have been recommended for quality control purposes. Simplicity of the statistical treatment is emphasized. The mercury content of certified reference materials is determined using the Wickbold combustion unit, and the resulting data are analyzed statistically.     

Pulse mode operation of Love wave devices for biosensing applications

In this work we present a novel pulse mode Love wave biosensor that monitors both changes in amplitude and phase. A series of concentrations of 3350 molecular weight poly(ethylene glycol) (PEG) solutions are used as a calibration sequence for the pulse mode system using a network analyzer and high frequency oscilloscope. The operation of the pulse mode system is then compared to the continuous wave network analyzer by showing a sequence of deposition and removal of a model mass layer of palmitoyl-oleoyl-sn-glycerophosphocholine (POPC) vesicles. This experimental apparatus has the potential for making many hundreds of measurements a minute and so allowing the dynamics of fast interactions to be observed.     

Recent developments with light-exposure apparatus and measurement of radiation of their light sources

New techniques and devices which were recently developed in order to avoid various drawbacks of current light-exposure apparatus are introduced. The spectral distribution of the open flame carbon arc approximates more closely to that of sunlight by modifications of the filter system.The life of carbon arcs was lengthened more than two fold. The long-life xenon arc lamp minimized the reduction in output of radiation.The slanted holder improved the locational variance of radiation falling on a specimen.The instrumental methods for measuring light dosage are explained.     

Infrared glass fibers for in-situ sensing, chemical and biochemical reactions

Infrared optical fibres based on chalcogenide glasses have been designed for evanescent wave spectroscopy. The sensitivity of the optical sensor is improved in tapering the sensing zone by chemical etching and the working optical domain of the system has been tested on a chloroform sample. This original remote sensor, based on the analysis of infrared signatures, has been applied to follow the fermentation process in cider fabrication as well as to detect and monitor a bacterial biofilm.     

Equation of state for high density solid and melt polyethylene

Pressure‐volume‐temperature (PVT) measurements for high‐density linear polyethylene (LPE) are studied experimentally over a temperature range of 290 to 470 K and pressures up to 3.1 kbar. For melt, the results can be represented by the Tait equation within the precision of the data. It is noticed that for each isotherm, an abrupt departure from the Tait representation occurs at a particular pressure. This is ascribed to onset of solidification due to pressure. Further, variation of the degree of crystallinity with pressure at various temperatures has been investigated. Finally, the PVT data has been analyzed in terms of the LJD cell theory in its original form without any modifications or simplifications of the cell potential. Satisfactory agreement is obtained between experiment and theory over the entire range of PVT data both in solids and melt states. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1618–1623, 2005