Wyniki wyszukiwania - Biblioteka Nauki

1

Diffraction of a cylindrical electromagnetic wave by a dielectric half-plane

100%

Ahmad S.

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tom Vol. 28, nr 2

71-80

EN

An electromagnetic diffraction of a cylindrical wave (emanating from a line source) by a dielectric half-plane is investigated. The problem is solved using integral transforms, the Winer-Hopf technique and asymptotic approximations. The factorizations of kernel functions are accomplished. It is observed that the reflected waves cease to exist if the angle of incidence takes up the value tan -1(1/n), where n represents the refractive index of the material of the half-plane under consideration.

2

Mass violence detection using data mining techniques

63%

Varma R. , Ahmad S.

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tom 113

3

Quantitative analysis of berberine in Berberis aristata fruits and in a traditional anti-inflammatory unani formulation by use of a validated HPLC method

45%

Kamal Y. T. , Singh M. , Tamboli E. T. , Parveen R. , Ahmad S.

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tom Vol. 23, no. 1

157--168

EN

A validated reversed-phase HPLC method has been developed for quantitative analysis of berberine in Berberis aristata fruits and in a polyherbal formulation. Separation of berberine was achieved on a C18 column with a mobile phase consisting of a 10–80% acetonitrile gradient in 0.05% aqueous orthophosphoric acid. The flow rate was 1 mL min-1. Detection was at 266 nm. A sharp, well defined peak was obtained at a retention time of 10.0 ± 0.4 min. The method was validated in accordance with ICH guidelines for accuracy, precision, robustness, and the limits of detection (LOD) and quantification (LOQ). Results from linear regression analysis were indicative of a good linear relationship (r2 = 0.998 ± 0.0011) in a wide concentration range (5–500 μ g mL-1). LOD and LOQ were 1.5 and 5.3 μg mL-1, respectively. Satisfactory recovery results (94.6–103.1%) were obtained by the method of standard addition. Intra-day, inter-day, and intersystem precision was satisfactory, with relative standard deviation in the range 0.7–1.8%. The berberine content of fruit of Berberis aristata and the herbal formulation were 0.033% and 0.0089% (w/w), respectively. This HPLC method for quantification of berberine can be used for quality control and standardization of several crude drugs and different herbal formulations in which berberine is present as a phyto constituent.

4

Parametric optimization of coal desulfurization through Alkaline leaching

45%

Rehman F. , Ahmad S. W. , Zafar M. S. , Ahmad S. , Zia-Ul-Haq M.

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2018

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tom Vol. 20, nr 3

103--109

EN

Desulfurization of Pakistani coal has been carried out through alkaline leaching. During present experimental investigation, the effect of operating parameters like alkali concentration, time, temperature and particle size has also been analyzed, graphically represented and critically discussed. Parametric optimization of leaching process has been carried out by using response surface methodology (RSM) based on central composite design (CCD). The analysis of variance (ANOVA) was performed in order to assess the highest level interactions of variables and three way interactions were observed significant. Further, the optimum value of total sulfur removal was observed as 53% when the operatic conditions fixed at 10% W/V, 60 min, 80°C and 140 mesh for alkaline concentration, leaching time, temperature and particle size, respectively.

5

Parametric optimization of rice bran oil extraction using response surface methodology

45%

Ahmad S. W. , Javed F. , Ahmad S. , Akram M. , Rehman A.

Polish Journal of Chemical Technology

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2016

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tom Vol. 18, nr 3

103--109

EN

Use of bran oil in various edible and nonedible industries is very common. In this research work, efficient and optimized methodology for the recovery of rice bran oil has been investigated. The present statistical study includes parametric optimization, based on experimental results of rice bran oil extraction. In this study, three solvents, acetone, ethanol and solvent mixture (SM) [acetone: ethanol (1:1 v/v)] were employed in extraction investigations. Response surface methodology (RSM), an optimization technique, was exploited for this purpose. A five level central composite design (CCD) consisting four operating parameter, like temperature, stirring rate, solvent-bran ratio and contact time were examined to optimize rice bran oil extraction. Experimental results showed that oil recovery can be enhanced from 71% to 82% when temperature, solvent-bran ratio, stirring rate and contact time were kept at 55°C, 6:1, 180 rpm and 45 minutes, respectively while fixing the pH of the mixture at 7.1.

6

Responses of the antioxidative enzymes in Malaysian rice (Oryza sativa L.) cultivars under submergence condition

45%

Damanik R. I. , Maziah M. , Ismail M. R. , Ahmad S. , Zain A. M.

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nr 4

EN

The potential involvement of activated oxygen species by submergence stress was studied in two Malaysian rice cultivars, MR219-4 and MR219-9, and cultivar FR13A that is known to be tolerant to submergence. Seedlings of these three rice cultivars were subjected to different submergence periods (4, 8, and 12 days). Under 8 days of complete submergence, FR13A cultivar showed higher lipid peroxidation in terms of malondialdehyde level and activities of antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) when compared to the MR219-4 and MR219-9 cultivars. MR219-9 showed higher SOD, APX, and GR activities after 12 days of submergence. The levels of SOD activity indicated that detoxification of O₂⁻ to H₂O₂ was maintained at a stable level throughout the submergence stress until up to 8 days and increased rapidly at 12 days of submergence. The results indicated that tolerance to submergence in rice is associated until 8 days submergence for MR219-4 and FR13A cultivars. These findings suggested that tolerance to submergence stress in rice might be proven by increased the capacity of antioxidative system. In addition, CAT activity has much higher affinity for scavenges H₂O₂ than APX. Therefore, ascorbate glutathione cycle might be more efficient to scavenge H₂O₂.

7

Inhibition of hypoxia-induced tolerance to subsequent hyperoxic injury in lung cells by phosphatidyl inositol 3-kinase inhibitors: LY294002 and wortmannin

45%

Ahmad S. , Ahmad A. , Gerasmivoskaya E. , Stenmark K. R. , White C. W.

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2003

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tom 08

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nr 2A

8

Stability-indicating high-performance thin-layer chromatographic method for analysis of terbinafine in pharmaceutical formulations

38%

Ahmad S. , Jain G. K. , Faiyazuddin M. , Iqbal Z. , Talegaonkar S. , Sultana Y. , Ahmad F. J.

Acta Chromatographica

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2009

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tom Vol. 21, no. 4

631--639

EN

A new, simple, selective, precise, robust and stability-indicating high-performance thin-layer chromatographic (HPTLC) method has been established for analysis of terbinafine hydrochloride (TH) in the bulk drug and in pharmaceutical formulations. Separation was achieved on aluminium plates precoated with silica gel 60F 254 , with toluene-ethyl acetate-formic acid 4.5:5.5:0.1 ( v/v ) as mobile phase. Densitometric analysis was performed at 284 nm. Compact bands of TH were obtained at R F 0.31 ± 0.02. Linearity ( r 2 = 0.9985), limit of quantification (35 ng per band), recovery (97.6−101.6%), and precision (≤2.19) were satisfactory. The method was applicable for routine analysis and accelerated stability testing of TH in pharmaceutical drug-delivery systems. Because the method can effectively separate the drug from its degradation products, it can be used as a stability-indicating method.

9

Development and validation of a stability-indicating HPLC method for analysis of celecoxib (CXB) in bulk drug and microemulsion formulations

38%

Baboota S. , Faiyaz S. , Ahuja A. , Ali J. , Shafiq S. , Ahmad S.

Acta Chromatographica

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2007

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tom No. 18

116-129

EN

A simple, economic, selective, precise, and stability-indicating HPLC method has been developed and validated for analysis of celecoxib (CXB), a selective COX-2 inhibitor, both in bulk drug and in microemulsions. Reversed-phase chromatography was performed on a C18 column with methanol–water, 75:25 (%, v/v), as mobile phase at a flow rate of 1.25 mL min-1. Detection was performed at 250 nm and a sharp peak was obtained for CXB at a retention time of 4.8 ± 0.01 min. Linear regression analysis data for the calibration plot showed there was a good linear relationship between response and concentration in the range 0.27–80 µg mL-1; the regression coefficient was 0.996 and the linear regression equation was y = 48415x + 54359. The detection (LOD) and quantification (LOQ) limits were 0.086 and 0.2625 µg mL-1 respectively. The method was validated for accuracy, precision, reproducibility, specificity, robustness, and detection and quantification limits, in accordance with ICH guidelines. Statistical analysis proved the method was precise, reproducible, selective, specific, and accurate for analysis of CXB. The wide linearity range, sensitivity, accuracy, short retention time, and simple mobile phase imply the method is suitable for routine quantification of CXB with high precision and accuracy.

10

Impact of family-based selection on growth performance and immune response of Japanese quail

36%

Rehman A. , Hussain J. , Mahmud A. , Javed K. , Ghayas A. , Ahmad S. , Rehman A. , Hussain J. , Mahmud A. , Javed K. , Ghayas A. , Ahmad S.

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nr 4

11

Preparation of Conductive Polyethylene Terephthalate Yarns by Deposition of Silver & Copper Nanoparticles

32%

Ahmad S. , Ashraf M. , Ali A. , Shaker K. , Umair M. , Afzal A. , Nawab Y. , Rasheed A.

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tom Vol. 25, no. 5 (125)

25--29

EN

The assemblage of textiles and electronics in a single structure has led to the development of smart textiles for functional purposes and special products. Conductive yarn as a necessary component of smart textiles is being developed by a number of techniques. The objective of the current study was to impart conductivity to yarn by coating the silver and copper nanoparticles on the surface of multifilament polyester textile fibres. The surface morphology and electrical conductivity of the coated yarns were investigated. The wash ability of the conductive yarns developed was also studied. The yarns showed good retention of the nanoparticles, as proven by the very small loss of the conductivity of the material.

PL

Połączenie tekstyliów i elektroniki w jednej strukturze doprowadziło do rozwoju inteligentnych tekstyliów znajdujących zastosowanie w celach funkcjonalnych i produktach specjalnych. Przędza przewodząca, jako niezbędny składnik inteligentnych wyrobów włókienniczych, może być otrzymywana za pomocą szeregu różnych technik. Celem badania było nadanie przewodnictwa przędzy poliestrowej poprzez powlekanie jej nanocząsteczkami srebra i miedzi. Zbadano morfologię powierzchni i przewodnictwo elektryczne powleczonych przędz, a także ich odporność na pranie. Przędze wykazywały dobrą retencję nanocząstek, co potwierdzała bardzo mała utrata przewodności materiału.

12

Prevalence of multi-drug resistant Mycobacterium tuberculosis in Khyber Pakhtunkhwa – a high tuberculosis endemic area of Pakistan

32%

Ali S. , Khan M. T. , Khan A. S. , Mohammad N. , Khan M. M. , Ahmad S. , Noor S. , Jabbar A. , Daire C. , Hassan F.

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nr 2

13

Growth, yield and nutritional performance of sweet sorghum and legumes in sole and intercropping influenced by type of legume, nitrogen level and air quality

32%

Arshad M. , Nawaz R. , Ahmad S. , Shah G. A. , Faiz F. , Ahmad N. , Irshad M. A. , Ranamukhaarachchi S. L.

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nr 1

14

A Statistical Approach for Obtaining the Controlled Woven Fabric Width

32%

Shaker K. , Umair M. , Maqsood M. , Nawab Y. , Ahmad S. , Rasheed A. , Ashraf M. , Basit A.

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2015

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tom Vol. 15, no. 4

275--279

EN

A common problem faced in fabric manufacturing is the production of inconsistent fabric width on shuttleless looms in spite of the same fabric specifications. Weft-wise crimp controls the fabric width and it depends on a number of factors, including warp tension, temple type, fabric take-up pressing tension and loom working width. The aim of this study is to investigate the effect of these parameters on the fabric width produced. Taguchi’s orthogonal design was used to optimise the weaving parameters for obtaining controlled fabric width. On the basis of signal to noise ratios, it could be concluded that controlled fabric width could be produced using medium temple type and intense take-up pressing tension at relatively lower warp tension and smaller loom working width. The analysis of variance revealed that temple needle size was the most significant factor affecting the fabric width, followed by loom working width and warp tension, whereas take-up pressing tension was least significant of all the factors investigated in the study.

15

Drought tolerance in citrus rootstocks is associated with better antioxidant defense mechanism

32%

Hussain S. , Khalid M. F. , Saqib M. , Ahmad S. , Zafar W. , Rao M. J. , Morillon R. , Anjum M. A.

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nr 08