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排序方式: 共有453条查询结果,搜索用时 15 毫秒
51.
A. Arunkumar P. Ramasamy K. Vishnu M. K. Jayaraj 《Journal of Materials Science》2014,49(10):3598-3607
Potassium succinate–succinic acid (KSSA), semi-organic single crystals were grown by slow evaporation growth technique using water solvent. Single crystal X-ray diffraction study revealed that the KSSA crystal belongs to monoclinic system. FT-IR and FT-Raman spectral studies were performed to identify the vibrations of functional groups. TGA/DTA analyses were carried out to characterize the melting behavior and stability of the title compound. The UV–Vis–NIR spectrum showed that the grown crystal is transparent in the entire visible region. Fluorescence studies were carried out in the range of 200–700 nm. The optical nonlinearity of KSSA was investigated at 532 nm using 7 ns laser pulses, employing the open aperture Z-scan technique. The photoconductivity study was carried out to know the conducting nature of the crystal. The laser damage threshold was measured using Q-switched Nd:YAG laser (1064 nm). Electrical properties of the crystal are studied using Hall Effect measurement. 相似文献
52.
Screen-printing technology is used to fabricate large dye-sensitized solar cells (DSSCs). The high series-resistance associated with transparent conductive oxide glass substrates causes poor performance in large DSSCs especially at an exposure of 1 sun. The DSSC design has an embedded silver grid; a fluorine-doped tin oxide (FTO) glass substrate and stripe type titanium dioxide (TiO2) active layers introduced by screen-printing. The counter electrode is prepared from a screen printable paste based on hexachloro platinic acid. A DSSC module, which consists of five stripe-type working electrodes on a 5 cm × 5 cm, embedded silver grid FTO glass substrate, shows stable performance with an energy conversion efficiency of 5.45% under standard test conditions. 相似文献
53.
V.R. Radhakrishnan M. Ramasamy H. Zabiri V. Do Thanh N.M. Tahir H. Mukhtar M.R. Hamdi N. Ramli 《Applied Thermal Engineering》2007,27(17-18):2791-2802
The crude preheat train (CPT) in a petroleum refinery consists of a set of large heat exchangers which recovers the waste heat from product streams to preheat the crude oil. In these exchangers the overall heat transfer coefficient reduces significantly during operation due to fouling. The rate of fouling is highly dependent on the properties of the crude blends being processed as well as the operating temperature and flow conditions. The objective of this paper is to develop a predictive model using statistical methods which can a priori predict the rate of the fouling and the decrease in heat transfer efficiency in a heat exchanger. A neural network based fouling model has been developed using historical plant operating data. Root mean square error (RMSE) of the predictions in tube- and shell-side outlet temperatures of 1.83% and 0.93%, respectively, with a correlation coefficient, R2, of 0.98 and correct directional change (CDC) values of more than 92% show that the model is adequately accurate. A case study illustrates the methodology by which the predictive model can be used to develop a preventive maintenance scheduling tool. 相似文献
54.
Ashok Kavithamani Venugopal Manikandan Nanjundappan Devarajan 《Journal of Electronic Testing》2011,27(5):673-678
A method for detection of parametric faults occurring in linear analog circuits based on location of poles of the Circuit
Under Test (CUT) is proposed. In the proposed method, the value of each component of the CUT is varied within its tolerance
limit using monte carlo simulation. The upper and lower bounds of magnitude, phase angle, real part and imaginary part of
all poles of the CUT are obtained. While testing, the locations of poles are obtained. If any one or more of the poles lies
outside the tolerance limit then the CUT is declared faulty. The effectiveness of the proposed method is validated through
two benchmark circuits like second order sallenkey band pass filter and fourth order leapfrog low pass filter. 相似文献
55.
The electrochemical reactions of two blood coagulation proteins, factors V and VIII (AC globulin and antihemophila factor) at platinum -NaCl interface were investigated using cyclic voltammetric techniques. Voltammograms were recorded for three concentrations of each of the proteins (0·1, 1·0 and 10 times the physiologic concentration) at different scan rates. The results of this preliminary study suggest that these compounds take part in more than one electron transfer reaction at the interface. Some of these may be coupled with chemical reactions. With both the proteins, particularly at lower concentrations, their adsorption has a significant influence on the peak current functions. Prediction as to the detailed type or nature of these reactions is not feasible at the present time due to the complexity of the molecules and to the lack of structural information of the proteins. 相似文献
56.
57.
C. Sekar C. R. V. Rao C. Subramanian P. Ramasamy 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(3):343-358
Good quality C60 crystals have been grown from high purity C60 powder and fullerene mixture (C60/C70) by vacuum sublimation method. The grown crystals were characterized with Optical microscopy, SEM, powder XRD, High Performance Liquid Chromatography and Raman spectroscopic analyses. 相似文献
58.
Single crystals of CulnS2, CulnSe2, CulnTe2, CuGaS2, AgGaS2 CulnSSe, AgGaSSe have been grown by chemical vapour transport technique on the basis of a new general thermodynamical model which enables the minimum source temperature T
s, and the minimum deposition temperature, T
d, to be determined. X-ray analysis, X-ray photoelectron spectroscopic analysis, surface analysis, and microhardness studies have been carried out on the single crystals grown. 相似文献
59.
Govindasamy Kottur Selvaraj Venkatesan Ramasamy Shanmugasundaram Senthil Kumar Subramanian Murugesan 《Journal of the science of food and agriculture》2010,90(9):1533-1537
BACKGROUND: Quality of tea depends on the cultivar and climatic conditions. Biochemical pathways within the plant and climatic factors can result in noticeable changes in chemical composition, which determine the quality of tea. Black tea quality attributes are influenced by various forms of catechins, namely gallated, non‐gallated, dihydroxylated and trihydroxylated catechins and their ratios. Hence the variations in grouped catechins and their synthesizing enzyme in relation to quality of south Indian black tea grown in different seasons and different cultivars were studied. RESULTS: Gallated, non‐gallated, dihydroxylated, trihydroxylated catechins and catechin index were significantly higher in crop shoots harvested during summer. A significant and wide diversity in various forms of catechins was noticed among the cultivars tested. Among the cultivars, UPASI‐3 registered the higher amount of various forms of catechins and activity of phenylalanine ammonia lyase (PAL), followed by UPASI‐9 and UPASI‐17 respectively, while the lowest amount was exhibited by ‘Assam’ seedlings and TRI‐2043. CONCLUSION: Overall quality as evaluated by tea tasters was positively correlated to the cultivars and seasons tested. This positive correlation can be attributed to higher levels of grouped catechins and PAL activity. Thus the contents of various forms of catechins could be the most important quality parameter of the south Indian black teas. Copyright © 2010 Society of Chemical Industry 相似文献
60.
The electrocatalytic reduction of hydrogen peroxide (H2O2) has been studied at nanostructured copper (Cunano) modified glassy carbon (GC/Cunano) electrode in phosphate buffer (pH 7.2). The electrical properties of GC/Cunano modified electrodes were studied by electrochemical impedance spectroscopy (EIS). Surface and electrochemical characterization
were carried out by using atomic force microscopy (AFM) and cyclic voltammetry. A well-defined H2O2 reduction signal, which is due to mediation of a surface active site redox transition exhibits at the GC/Cunano electrode. The Cunano is acting as a bridge without the aid of any other electron mediator, which enables the direct electron transfer between
the modified electrode and the substrate. The results are compared with bulk copper macroelectrode and emphasized the efficiency
of the Cunano modified electrode. Systematic investigations were made to optimize the experimental parameter, such as applied potential
(Eapp) for copper electrodeposition. The calibration curve obtained from chronoamperometric studies was found to be linear in the
range 0.5 to 8.0 μM H2O2 with a detection limit of ca.10 nM (S/N = 3) at the GC/Cunano electrode. The modified electrode is stable for 1 week in phosphate buffer after repetitive measurements. 相似文献