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1

Approximation properties of certain summation integral type operators

Patel P., Mishra V. N.

Demonstratio Mathematica

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2015

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Vol. 48, nr 1

77--90

EN

In the present paper, we study approximation properties of a family of linear positive operators and establish direct results, asymptotic formula, rate of convergence, weighted approximation theorem, inverse theorem and better approximation for this family of linear positive operators.

2

The ICH guidance in practice: Stress degradation studies on irbesartan and development of a validated stability-indicating UPLC assay

Sahu K, Patel P, Karthikeyan C, Trivedi P

Acta Chromatographica

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2010

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Vol. 22, no. 2

189--205

EN

In this research work comprehensive stress testing of irbesartan was carried out according to ICH guideline Q1A (R2), and a stability-indicating reversed-phase ultra-performance liquid chromatographic (UPLC) assay was established. The drug was subjected to acid (0.1 M HCl), neutral, and alkaline (0.1 M NaOH) hydrolytic conditions at 80°C, and to oxidative decomposition at room temperature. Photolysis was carried out by exposing the drug to sunlight (60,000–70,000 lux) for two days. The solid drug was also subjected to 50°C for 60 days in a hot-air oven. Degradation of the drug was found to occur under alkaline, acidic, and neutral hydrolytic conditions. Separation of the drug and the degradation products was successfully achieved on a BEH (bridged ethylene hybrid) C 18 column with 40:60 aqueous glacial acetic acid (0.2%)-acetonitrile as mobile phase. The flow rate and detection wavelength were 0.1 mL min -1 and 229 nm, respectively. The method was validated and response was found to be linear in the drug concentration range 10–50 μg mL -1 The mean values (±RSD, %) of slope, intercept, and correlation coefficient were 32102 (± 0.0535), 1295 (± 3.02), and 0.9998 (± 0.0493), respectively. RSD in intra-day and inter-day precision studies was <1%. Recovery of the drug from a mixture of degradation products was between 99.26 and 100.01%. The method was specific to the drug, selective to degradation products, and robust. PDA purity test also confirmed the specificity of the method.

3

Study the effect of commingling parameters on Glass / Polypropylene hybrid yarns properties

Mankodi H., Patel P

Autex Research Journal

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2009

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Vol. 9, no. 3

70--73

EN

The objective of this paper is to discuss effect of commingling parameter on characteristics of Glass/Polypropylene commingled hybrid yarns to get homogenous mix of matrix and reinforcement elements in the final yarn. A commingling machine developed to produce hybrid yarn using two techniques viz. mingling technique and hollow spindle wrapping technique using single machine is highlighted .The machine can run at speed upto 800 meters/min and for hybrid yarn it can go up to 200 meters/min. To study the effect of parameter three variable namely Air pressure, Overfeed and Take-up speed are take in to consideration and the Box-Behanken design is used for experimental setup. The hybrid yarn samples have been evaluated to investigate the influence of process variables the commingling characteristics of hybrid yarn viz. nip frequency; nip stability and nip regularity have also been studied. 'MINITAB' software is used for the analysis of test results. It was observed that effects of individual parameter as well as interaction effects are equally important in deciding final yarn quality. The structural analysis of hybrid yarn is done using SEM (Scanning electron microscope). To study the mixing behaviour of glass/polypropylene hybrid yarn three different methods have been used to prepare hybrid yarn viz. Friction spinning, hollow spindle wrapping, commingling. Its was clearly observed that commingled process gives better homogenous mixing of glass and polypropylene filaments compare to other two method. This yarn is used to make final laminate sample using hot press.