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951.
952.
This paper extends the fractional programming problem with set-inclusive constraints studied earlier by replacing every coefficient vector in the objective function with a convex set. A dual is formulated, and well-known duality results are established. A numerical example illustrates the dual strategy to obtain the value of the initial problem.The research of the first author was conducted while he was on sabbatical at the Department of Operations Research, Stanford University, Stanford, California. The financial assistance of the International Council for Exchange of Scholars is gratefully acknowledged. The author is grateful to the Department of Operations Research at Stanford for the use of its research facilities. 相似文献
953.
Forced degradation study on gliclazide was conducted under the conditions of hydrolysis, oxidation, dry heat and photolysis and an isocratic stability-indicating HPLC-UV method was developed and validated. All the seven degradation products (I–VII) formed under different conditions were optimally resolved on a C18 column with mobile phase composed of 40% acetonitrile and 60% ammonium acetate solution (0.025 M, pH 3.5) at a flow rate of 0.25 mL min?1 using 235 nm as detection wavelength. The method was linear between 5–500 μg mL?1 drug concentrations. The %RSD of intra- and inter-day precision studies was <1 and <2% respectively. Excellent recoveries (99.81–100.97%) proved the method sufficiently accurate. Each peak resolved always with a resolution of >1.90 indicating the method to be rugged enough. The method was used to study the drug degradation behaviour under the forced conditions. Four degradation products (I–IV) were formed in 0.1 N HCl and water whereas only I and III were formed in 3% H2O2. Two new products V and VI in addition to I, III and IV were formed in 0.1 N NaOH. The drug was stable to thermal and photolytic decomposition. The degradation behaviour in water and 0.1 N NaOH was similar under dark and light conditions but a new product VII was formed in 0.01 N HCl in light. In general, the rate of degradation was accelerated by the light. The method was applied successfully in stability testing of gliclazide tablets. 相似文献
954.
1,4-Dioxane is a flammable liquid and tends to form explosive peroxides. Its formation in glycols (low parts-per-million levels), which are used as dehumidifying agents in refineries, may take place by condensation. 1,4-Dioxane thus formed gets distilled over with benzene in the refinery process. Therefore, it is necessary to identify and determine the levels of 1,4-dioxane in glycols as well as benzene. Gas chromatography (GC) is probably the best technique for this purpose. GC analysis may be carried out using a flame ionization detector. Results show that 1,4-dioxane can be comfortably determined down to 2 ppm in glycols and benzene. 相似文献
955.
B. S. Randhawa D. K. Chhabra Sandeep Kaur 《Journal of Radioanalytical and Nuclear Chemistry》1986,105(1):13-18
Mössbauer spectra of a series of the complexes of the type Na3[Fe/RCOO/6]xH2O /R=H, CH3, C2H5, C6H5/ has been recorded at 298±2 K. All display a quadrupole doublet with isomer shift and quadrupole splitting values in agreement with high spin iron/III/ octahedral geometry. The quadrupole splitting show an increasing trend with increasing polarizability of the substituent anion /RCOO–/. A linear correlation between quadrupole splitting values and the /Fe–O/ stretching frequencies has also been observed. 相似文献
956.
B. S. Randhawa P. S. Bassi Sandeep Kaur 《Journal of Radioanalytical and Nuclear Chemistry》1994,188(4):279-286
Thermal decomposition of lithium tris (malonato) ferrate (III) tetrahydrate i.e. Li3[Fe(CH2C2O4)3].4H2O has been studied in the temperature range of 353–873 K in static air atmosphere using Mössbauer, infrared spectroscopy and nonisothermal techniques (TG-DTG-DTA). The anhydrous complex decomposed into ferric oxide of varying particle sizes and alkali metal malonates/carbonates in succesive stages. Fimally a solid state reaction between -Fe2O3 and alkali metal carbonate gives fine particles of lithium ferrite (LiFeO2) at a temperature lower than for oxalate precursor and for ceramic method. 相似文献
957.
Navneet Kaur 《Tetrahedron letters》2004,45(37):6883-6885
N-α-Boc-l-Histidine upon direct τ(N-1) ring alkylation with various alkyl halides in the presence of sodium hydride in DMF or CH3CN easily afforded N-α-Boc-1-alkyl-l-histidines 2a-f. The reaction works equally well in either DMF or CH3CN as solvent, however, CH3CN is preferred due to ease of reaction work-up. 相似文献
958.
B. S. Randhawa P. S. Bassi Sukhraj K. Randhawa Sandeep Kaur 《Journal of Radioanalytical and Nuclear Chemistry》1990,145(4):249-257
Solid state photolysis of alkaline earth tris/malonato/ferrates/III/, i.e., M3[Fe(CH2C2O4)3]2.xH2O /M=Mg, Ca, Sr, Ba/ has been investigated employing Mössbauer, infrared and reflectance spectroscopic techniques. The complexes were irradiated for 400 h using a medium pressure mercury vapour lamp of 250 Watts. Photoreduction led to the formation of M[FeII(CH2C2O4)2(H2O)2]. The extent of photoreduction showed the following order: Ca>Sr>Mg>Ba. The results have been compared with those of analogous alkaline earth tris/oxalato/ferrates/III/. 相似文献
959.
A new ion-selective PVC membrane electrode based on salicylaldehyde thiosemicarbazone as an ionophore is developed successfully as sensor for mercury(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear log[Hg2+] versus EMF response over a wide concentration range of 1.778×10−6-1.0×10−1 M with Nernstian slope of 29 mV per decade with the detection limit of 1.0×10−6 M. The response time of the electrode is less than 30 s and the membrane electrode operates well in the pH range of 1.0-3.0. The lifetime of the sensor is about 2 months. The electrode shows better selectivity towards Hg2+ ions in comparison with the alkali, alkaline and some heavy metal ions; most of these metal ions do not show significant interference (KPotHg,M values of the order of 10−3-10−4). The present sensor showed comparable or even better performance vis-à-vis similar PVC based ion-selective electrodes reported in literature. The sensor was also applied as an indicator electrode for potentiometric titration of Hg2+ions with I− and Cr2O72−. 相似文献
960.
Navjeet Kaur Neha Ahlawat Yamini Verma Pooja Grewal Pranshu Bhardwaj Nirmala Kumari Jangid 《合成通讯》2020,50(8):1075-1132
AbstractOne of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review. 相似文献