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11.
Srinivasa R. Arikati C. Pandu Rangan Glenn K. Manacher 《BIT Numerical Mathematics》1991,31(2):181-193
An efficient reduction process for path problems on circular-arc graphs is introduced. For the parity path problem, this reduction gives anO(n+m) algorithm for proper circular-arc graphs, and anO(n+m) algorithm for general circular-arc graphs. This reduction also gives anO(n+m) algorithm for the two path problem on circular-arc graphs. 相似文献
12.
This paper provides an easily computable one parameter inspection policy for the detection of the failure of a system when the time to failure of the system follows a gamma distribution. This one parameter inspection policy, as suggested by Munford and Shahani, compares fairly well with a computationally difficult optimal policy suggested by Barlow, Hunter and Proschan. Necessary tables are provided for the "optimal" parameter for a wide range of the parameters of the problem, from which the successive inspection times can be computed easily. 相似文献
13.
V. Pandu Ranga Rao D. Satyanarayana A. Suryanarayana 《Fresenius' Journal of Analytical Chemistry》1962,191(3):202-204
Summary Conditions for the use of methyl orange as a redox indicator for the titration of iron(II), hydroquinone and oxalate with cerio ammonium nitrate dissolved in perchloric acid, have been established. It is found that methyl orange behaves as a reversible indicator with a transition potential of 955±10 mV. Nitric acid as a medium of titration is not satisfactory.
Zusammenfassung Methylorange kann als Redoxindicator bei der Titration von Eisen(II), Hydrochinon und Oxalat mit Cer(IV)-ammoniumnitrat in perchlorsaurer Lösung verwendet werden. Der Indicator hat ein Umschlagspotential von 955±10 mV. In salptersaurem Medium erhält man keine befriedigenden Werte.相似文献
14.
In a previous communication it was reported that vanadiumV gives an intense turquoise-blue colour with sulphosalicylic acid in concentrated sulphuric acid and that the colour reaction is specific and very sensitive for the detection of vanadiumV. During our studies on the nature of the complex, it was found that vanadiumIV gives a negative colour test and that the blue colour developed by the reagent with vanadiumV is discharged on the addition of a reducing agent like ironII, uraniumIV or hydroquinone. It was also observed that the blue colour is restored by the addition ceriumIV solution. This reversible property of the complex has been further investigated to see if the complex can be used as a redox indicator. 相似文献
15.
Summary A new specific color reaction for the detection of vanadium(V) has been described. This consists in treating the vanadium(V) solution with 0.1% sodium salicylate solution in a medium of 20 N sulphuric acid or sirupy phosphoric acid. A turquois blue color results. 相似文献
16.
Various metal complexes of 7-iodo-8-hydroxyquinoline-5-sulphonic acid (ferron) were found to be selectively extracted into immiscible alcohols. Vanadium(V) is almost completely extracted into n-butanol in a single extraction from solutions which are 0.05 M in sulphuric acid. A sensitive and selective spectrophotometric method can be based on this extraction. Beer's law is obeyed up to 15.3 μg of vanadium per ml; the sensitivity of the color reaction is 0.011 μg of vanadium per cm2 at 430 mμ. The interference of iron(III) can be eliminated by adding excess pyrophosphate. The extracted species appears to contain vanadium, ferron and n-butanol in the ratio 1:2:4. 相似文献
17.
Bharathi DV Naidu A Jagadeesh B Laxmi KN Laxmi PR Reddy PR Mullangi R 《Biomedical chromatography : BMC》2008,22(6):645-653
A highly sensitive and specific LC-MS/MS method has been developed and validated for the estimation of zafirlukast (ZFK) with 500 microL human plasma using valdecoxib as an internal standard (IS). The API-4,000 LC-MS/MS was operated under multiple reaction-monitoring mode using the electrospray ionization technique. The assay procedure involved extraction of ZFK and IS from human plasma with ethyl acetate. The resolution of peaks was achieved with 10 mm ammonium acetate (pH 6.4):acetonitrile (20:80, v/v) on a Hypersil BDS C(18) column. The total chromatographic run time was 2.0 min and the elution of ZFK and IS occurred at approximately 1.11 and 1.58 min, respectively. The MS/MS ion transitions monitored were 574.2 --> 462.1 for ZFK and 313.3 --> 118.1 for IS. The method was proved to be accurate and precise at a linearity range of 0.15-600 ng/mL with a correlation coefficient (r) of >or=0.999. The method was rugged with 0.15 ng/mL as lower limit of quantitation. The intra- and inter-day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers following oral administration of 20 mg ZFK tablet. 相似文献
18.
Adrián Bonilla-Petriciolet Gade Pandu Rangaiah Juan Gabriel Segovia-Hernández 《Fluid Phase Equilibria》2010
Parameter estimation for vapor–liquid equilibrium (VLE) data modeling plays an important role in design, optimization and control of separation units. This optimization problem is very challenging due to the high non-linearity of thermodynamic models. Recently, several stochastic optimization methods such as Differential Evolution with Tabu List (DETL) and Particle Swarm Optimization (PSO) have evolved as alternative and reliable strategies for solving global optimization problems including parameter estimation in thermodynamic models. However, these methods have not been applied and compared with respect to other stochastic strategies such as Simulated Annealing (SA), Differential Evolution (DE) and Genetic Algorithm (GA) in the context of parameter estimation for VLE data modeling. Therefore, in this study several stochastic optimization methods are applied to solve parameter estimation problems for VLE modeling using both the classical least squares and maximum likelihood approaches. Specifically, we have tested and compared the reliability and efficiency of SA, GA, DE, DETL and PSO for modeling several binary VLE data using local composition models. These methods were also tested on benchmark problems for global optimization. Our results show that the effectiveness of these stochastic methods varies significantly between the different tested problems and also depends on the stopping criterion especially for SA, GA and PSO. Overall, DE and DETL have better performance for solving the parameter estimation problems in VLE data modeling. 相似文献
19.
A very sensitive and specific test for vanadiumV is described using sulphosalicylic acid as reagent. When this reagent is brought into contact with solid vanadiumV (a drop of the test solution evaporated to dryness on a watch glass) in the presence of concentrated sulphuric acid or 80% syrupy phosphoric acid, a blue colour is developed. Using this colour reaction, it is possible to detect 0.05 μg of vanadiumV in 0.05 ml of test solution. AluminiumIII, arsenicV, berylliumII, cadmiumII, chromiumIII, chromiumVI, copperII, ironIII, molybdenumVI, nickelVI, tungstenVI, uraniumVI and vanadiumIV do not interfere with this colour test, although some of them are known to form coloured complexes with sulphosalicylic acid under different conditions. Reducing agents like ironII, uraniumIV, molybdenumV and hydroquinone discharge the colour. The colour of the vanadiumV-sulphosalicylic acid compound is also discharged if the temperature is raised to 60°, though it reappears on cooling. 相似文献
20.
Pankaj Kisan Chatki Kishore Kumar Hotha Pandu Ranga Reddy Kolagatla D. Vijaya Bharathi V. Venkateswarulu 《Biomedical chromatography : BMC》2013,27(7):838-845
A robust, specific and fully validated LC‐MS/MS method as per general practices of industry has been developed for estimation of lacidipine (LAC) with 100 μL of human plasma using lacidipine‐13C8 as an internal standard (IS). The API‐4000 LC‐MS/MS was operated under the multiple reaction‐monitoring mode. A simple liquid–liquid extraction process was used to extract LAC and IS from human plasma. The total run time was 3.0 min and the elution of LAC and IS occurred at 1.96 and 1.97 min; this was achieved with a mobile phase consisting of 5 mm ammonium acetate buffer–acetontrile (15:85 v/v) at a flow rate of 0.60 mL/min on a Zorbax SB C18 (50 × 4.6 mm, 5 µm) column. A linear response function was established for the range of concentrations 50–15,000 pg/mL (r > 0.998) for LAC. The current developed method has negligible matrix effect and is free from unwanted adducts and clusters which are formed owing to system such as solvent or mobile phase. The developed assay method was applied to an oral pharmacokinetic study in humans and successfully characterized the pharmacokinetic data up to 72 h. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献