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排序方式: 共有162条查询结果,搜索用时 31 毫秒
1.
Terasa Kubala Baldev Gambhir S. Ian Borst 《Drug development and industrial pharmacy》1993,19(7):749-757
A high performance liquid chromatography method is described for the determination of diclofenac sodium, its related compounds and degradation products in commercial sources of raw materials and solid dosage forms. This method is specific, accurate and stability indicating. The method employs a reverse-phase octylsilane (C18) column with a mobile phase composed of acetonitrile/methanol/pic B-6 (25:25:50) and detection at 229 nm. The method resolves six principal related compounds with quantitation in the range 0.3-1.5%. Assay recoveries by spiking commercial formulations with diclofenac sodium were 99.64 ± 1.30%. Drug content in several commercial formulations are reported. Accelerated stability tests were conducted on raw materials and drug products and 1-(2,6-dichlorophenyl)-2-indolin-2-one was identified for the first time as a degradation product in solid dosage forms which are stressed under humidity and heat. 相似文献
2.
Alok Singh Sitaram Dash Mohammed Kamruddin Puthupparampil K. Ajikumar Ashok K. Tyagi Vinjamoor S. Raghunathan Baldev Raj 《Journal of the American Ceramic Society》2002,85(4):927-932
Formation of nanocrystalline calcia from calcite has been studied in situ via transmission electron microscopy. The crystallographic transformation occurred via two mechanisms: the first is by distortion of the cleaved rhombohedron of calcite, formed by {104} planes in hexagonal coordinates, into a cube. This produced a microstructure of oriented, elongated nanocrystals of calcia with planar boundaries. In the second mechanism, the micrometer-sized parent calcite particles broke up into nano-sized grains as the decomposition began, leading to irregularly shaped, randomly oriented nanocrystals of calcia. 相似文献
3.
Anish Kumar Baldev Raj P. Kalyanasundaram T. Jayakumar M. Thavasimuthu 《NDT & E International》2002,35(4)
The impact echo technique is based on the use of transient stress waves for non-destructive detection of flaws in concrete structures. Impact-echo testing has been carried out for assessment of the structural integrity of the ring beam of a pressurised heavy water nuclear reactor. In order to develop the test procedure for carrying out impact echo testing, mock up calibration blocks were made. The detectability of the impact echo system has also been established in terms of the depth and the lateral dimension of the detectable flaw for the ring beam under consideration. Based on the optimised test parameters identified with the help of the studies carried out on the mock up blocks, impact echo testing was carried out on the ring beam of the reactor containment structure, for assessing its structural integrity. 相似文献
4.
S. K. Albert C. R. Das V. Ramasubbu A. K. Bhaduri S. K. Ray Baldev Raj 《Journal of Materials Engineering and Performance》2002,11(3):243-249
A root-cracked blade in a high-pressure steam turbine of a nuclear power plant had to be replaced with a new blade by cutting
the shroud to remove the cracked blade. This necessitated in situ welding of a new shroud piece with the existing shroud after
the blade replacement. The in situ welding of the shroud, a 12% Cr martensitic stainless steel with tempered martensite microstructure,
was carried out using gastungsten arc welding and 316L austenitic stainless steel filler metal followed by localized postweld
heat treatment at 873 K for 1 h using a specially designed electrical resistance-heating furnace. Mock-up trials were carried
out to ensure that sound welds could be made under the constraints present during the in situ repair welding operation. In
situ metallography of the repair weld after postweld heat treatment confirmed the adequate tempering of the martensitic structure
in the heat-affected zone. Metallurgical investigations carried out in the laboratory on a shroud test-piece that had been
welded using the same procedure as employed in the field confirmed the success of the in situ repair operation. The alternate
option available was replacing the cracked blade and the shroud piece to which it is riveted with a new one, reducing the
height of all the blades attached to the shroud by machining, riveting the blades with reduced height to the new shroud, and,
finally, dynamic balancing of the entire turbine after completion of the repair. This option is both time-consuming and expensive.
Hence, the successful completion of this repair welding resulted in enormous savings both in terms of reducing the downtime
of the plant and the cost of the repair. The turbine has been put back into service and has been operating satisfactorily
since December 2000. 相似文献
5.
U. Kamachi Mudali H. S. Khatak Baldev Raj M. Uhlemann 《Materials and Manufacturing Processes》2004,19(1):61-73
It is well known that the addition of nitrogen to steels and stainless steels enhances the passivity and localized corrosion resistance, in addition to improving the mechanical properties. Selective alloying of surfaces of steels and stainless steels with nitrogen could also enhance the corrosion resistance and improve the mechanical properties without affecting the bulk properties. Techniques like ion implantation, laser alloying, nitriding, etc. can be effectively used to introduce very high levels of nitrogen. In addition, these techniques can also produce modified surfaces with novel microstructures to further improve the properties. The surface alloying methods also provide an opportunity to selectively nitrogenate the surface of finished components in order to obtain better properties. The review highlights the techniques, modifications and the properties obtained further. 相似文献
6.
L. Satyanarayan Anish Kumar T. Jayakumar C. V. Krishnamurthy Krishnan Balasubramaniam Baldev Raj 《Journal of Nondestructive Evaluation》2009,28(3-4):111-124
New techniques developed using the array transducer, to image and size the bottom-surface and near-through-wall crack-like defects in thick carbon steel components are discussed. Three studies are reported here including (a) Optimal beam steering angle for focused and unfocused inspection using phased array method for bottom-surface crack sizing. (b) A front wall correction algorithm for sizing of near-through-wall crack-like defects. (c) A small aperture technique for sizing of near-through-wall crack-like defects. A Finite Difference Time Domain (FDTD) based simulation was used to study and verify the experimental observations. The application of time domain scheme relative arrival time technique (RATT), to measure the size of the near-through wall crack-like defects for the leak before break (LBB) criterion, was also investigated and found to be insufficient. A conventional SAFT algorithm was used for improving the sizing using the small aperture technique. 相似文献
7.
B. Sasi B. P. C. Rao T. Jayakumar Baldev Raj 《Transactions of the Indian Institute of Metals》2010,63(5):773-777
This paper discusses characterisation of microstructures in Ti-4.5Al-3Mo-1V (VT-14) alloy specimens solutionized in the temperature
range of 923K–1373K, using room temperature electrical resistivity measurements. Using phase angle of impedance change in
eddy current coil as a parameter, calibration curve between resistivity and phase angle has been established using three reference
specimens of known resistivity. The changes in the electrical resistivity of the specimens have been correlated with optical
microscopy investigations. The electrical resistivity of unstable β phase has been compared with α and α′ phases and possible
reasons for higher resistivity of β phase and lower resistivity of α′ have been given based on the rule of mixtures and scattering
and mobility of electrons. The electrical resistivity of α′ martensite phase of the chosen VT-14 alloy has been determined
as 1.04 αΩ-m. The studies reveal that it may be possible to identify the β transus temperature of α+β titanium alloys from
the electrical resistivity data. 相似文献
8.
P. Shankar P. Palanichamy T. Jayakumar Baldev Raj S. Ranganathan 《Metallurgical and Materials Transactions A》2001,32(12):2959-2968
The presence of even dilute concentrations of nitrogen (0.08 mass pct) is found to have a strong influence on the microstructure
of a nuclear grade 316LN austenitic stainless steel, thermally aged at 1123 K. High-resolution transmission electron microscopy
(TEM) evidence of pre-precipitation reactions involving formation of Cr-N rich clusters prior to Cr2N precipitation has been presented. A tendency for cellular precipitation has been observed on continued aging above 500 hours.
Beyond 1000 hours, chi precipitates are the most frequently seen phase. The observed microstructural variations correlate
well with ultrasonic velocity and attenuation measurements. The present study reveals that nitrogen in solid solution decreases
all the elastic constants, namely longitudinal modulus, elastic modulus, shear modulus, and bulk modulus in this steel but
has a negligible effect on Poisson’s ratio. The stages associated with the precipitation of intragranular coherent Cr2N are, however, associated with an increase in all the elastic constants including Poisson’s ratio. 相似文献
9.
10.
Electricity has played a pivotal role in the development of Punjab economy. Of late there has been a steep rise in the demand for electricity in the state. The present study undertakes a holistic view of growth of demand for electricity in the state. The technique applied is multiple regression and secondary data is used for the purpose of analysis. The study concludes that demand for electricity in the state is price inelastic but income elastic for majority of consuming sectors. An important policy implication thereof is that price hike will be ineffective in regulating and managing demand unless price is varied in an hourly basis. Therefore, the state has to resort to other demand-side management (DSM) measures, such as improving efficiency of electricity use and its conservation. Considering the high income elasticity of electricity demand, sufficient electricity-generating capacity needs to be created, since demand is expected to grow at an accelerated rate in future. This calls for a comprehensive electricity policy. The study further concludes that in the long run, price-demand as well as income-demand relationship in case of electricity is likely to remain uncertain especially in the post-reform era. 相似文献