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Effects of alkali solution concentration and soaking time on mechanical properties of coconut fibre

Kondo Y., Arsyad M., Ahmad A., Soenoko R., Arman A.

Archives of Materials Science and Engineering

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2023

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Vol. 124, nr 2

62--70

EN

Purpose: The study aims to determine the effect of the treatment of alkali solution concentration and soaking time on the mechanical properties of coconut fibre. Design/methodology/approach: The study consists of preparing materials and equipment, immersion of coconut fibre in an alkali solution, drying in a furnace, testing, analysis of test results, and conclusions. Materials and equipment used are coconut fibre, alkali solution, polyester matrix, distilled water, furnace, hydrolysis test, tensile test, and SEM analysis. The sample had two treatments; the first was coconut fibre, which was soaked in the sodium hydroxide solution with 5%, 10%, 15%, and 20% concentrations for 3 hours. The second treatment was coconut fibre soaked in the sodium hydroxide solution with a concentration of 20% for 1, 5, 7, 9, and 11 hours. The samples were then dried in a furnace at 90ºC for 5 hours, and then a hydrolysis test, tensile test, pull-out test, and SEM analysis were carried out. Findings: The results suggest that for immersion in an alkali solution of 20%, the highest tensile strength of coconut coir fibre was obtained in soaking for 3 hours at 280.94 N/mm2, and the highest bonding strength between coconut coir fibres with a matrix polyester was obtained at 5 hours immersion at 7.86 N/mm2. Research limitations/implications: In the given study, coconut fibre was treated by soaking it in 5%, 10%, 15%, and 20% sodium hydroxide solution. Then, a single fibre tensile test was carried out, and a pull-out test was carried out to determine the mechanical properties of coconut fibre as a required effect that had been given. Subsequent studies can be carried out with other treatments using other chemical solutions, such as hydrogen peroxide or potassium permanganate. Originality/value: The tensile strength of coconut fibre without treatment was 186.42 N/mm2, whereas after being immersed in 20% sodium hydroxide solution, the tensile strength became 280.94 N/mm2. Likewise, the shear strength of the interface between the fibre and the polyester matrix was 1.85 N/mm2 for untreated coconut fibre to 3.09 N/mm2 for coconut fibre soaked in a 20% sodium hydroxide solution. The results of the study are intended as data for the use of coconut fibre as a natural fibre-reinforced composite material, for example, as a raw material for fishing boat walls.

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Development and Validation of RP-HPLC Method for Simultaneous Estimation of Glibenclamide and Thymoquinone in Rat Plasma and Its Application to Pharmacokinetics

Ahmad A., Khan R. M. A., Alkharfy K. M.

Acta Chromatographica

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2015

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Vol. 27, no. 3

435--448

EN

A rapid, accurate, and sensitive reverse phase high-performance liquid chromatographic method was developed and validated for the simultaneous determination and quantification of glibenclamide and thymoquinone in rat plasma in the presence of internal standard (thymol). Chromatograms were developed with methanol, acetonitrile, and buffer (50:20:30, v/v/v) solvent system on a Symmetry® C18 (5 μm, 3.9 × 150 mm) column, and pH was adjusted to 4.5 with orthophosphoric acid. Mobile phase was pumped at a flow rate of 1.5 mL min-1 with 254 nm ultraviolet (UV) detection. Validation of the method was performed in order to demonstrate its selectivity, linearity, precision, accuracy, limits of detection, and quantification (LOD and LOQ). Standard curves were linear (r2 = 0.996 and 0.999 for glibenclamide and thymoquinone) over the concentration range 0.5–50 μg Ml-1. The coefficient of variation (CV) of < 6% and accurate recovery of 87.54–105.19% for glibenclamide and CV of <5% and accurate recovery of 86.08–103.19% for thymoquinone were found to be in the selected concentration range of 0.5–50 μg Ml-1. The lower limits of detection and quantitation of the method were 0.109 and 0.332 μg Ml-1 for glibenclamide and 0.119 and 0.361 μg Ml-1 for thymoquinone, respectively. The within and between-day coefficients of variation were less than 7%. The validated method has been successfully applied to measure the plasma concentrations in a drug interaction study of glibenclamide with thymoquinone in an animal model to illustrate the scope and application of the method.

3

Stimuli responsive polymeric nanoparticles in regulated drug delivery for cancer

Yadav D., Suri S., Chaudhary A.A., Hemant, Beg M. N., Asif M., Ahmad A.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 1

57-64

EN

Stimuli-responsive drug delivery system is a concept in which a drug is delivered at a suitable rate in response to stimuli. States of diseases may cause an alteration in some parameters of the body (e.g. in tumors) and the onset and offset of the drug delivery can be done by using this as a stimuli or a "trigger". Stimuli-responsive ("intellectual" or "sharp") resources and molecules show abrupt property changes in response to miniature changes in external stimuli such as pH, temperature etc. For regulated drug delivery, environmental stimuli such as pH and temperature, which undertake phase transition in polymer system, have been investigated. Thermally-responsive polymers can be tuned to a preferred temperature variety by copolymerization with a hydrophilic co-monomer or a hydrophobic co-monomer. Hydrophilic co-monomers increase the LCST while hydrophobic co-monomers decrease the LCST. The stimuli responsive polymer for regulated drug delivery can contain a polymer and copolymers having equilibrium of hydrophilic and hydrophobic groups. A number of these polymers have been investigated extensively and some success in drug delivery with them has been achieved, such as polymers and copolymers of N-isopropylacrylamide, PLGA, and PLA, HEMA etc. Thus this review is designed for stimuli pH and temperature responsive polymeric nanoparticles, which would be helpful to treat various cronic diseases such as cancer and others, for scientists in the field of the regulated drug delivery system.

4

Development and validation of HPTLC method for the estimation of diosgenin in In Vitroculture and rhizome of Dioscorea deltoidea

Amir M, Ahmad A., Siddique N. A, Mujeeb M, Ahmad S., Siddique W. A

Acta Chromatographica

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2012

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Vol. 24, no. 1

111--121

EN

A new simple, accurate, selective, precise, economical and stability-indicating high-performance thin layer chromatographic method for the analysis of diosgenin in callus and rhizome of Dioscorea deltoidea was developed and validated. The method was developed on TLC aluminium plates precoated with silica gel 60F254 using solvent system petroleum ether-isopropanol (12:1, v/v), which gives a compact spot of diosgenin (RF value 0.76 ± 0.02). Densitometric analysis of diosgenin was carried out in the absorbance mode at 366 nm after spraying with methanolic sulphuric acid. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.991 and 0.995 for diosgenin with respect to peak height and peak area, respectively, in the concentration range of 100–1000 ng per spot. The limits of detection and quantification for diosgenin were 16.58 and 50.25 ng per spot. The proposed method was applied for determination of diosgenin in rhizome of D. deltoidea (0.047% w/w) as well as in in vitro culture (callus) (0.092% w/w). Statistical analysis proves that the method is repeatable, selective and accurate for the estimation of diosgenin in D. deltoidea. The developed method effectively resolved the diosgenin in D. deltoidea; hence, it can be employed for routine analysis as a stability indicating method.

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A validated stability-indicating method for simultaneous analysis of mevastatin and pravastatin in fermentation broth during bioconversion by Actinomadura macra

Ahmad A., Panda B. P, Mujeeb M

Acta Chromatographica

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2011

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Vol. 23, no. 1

121--131

EN

A simple, accurate, selective, precise, economical, and stability-indicating high-performance thin-layer chromatographic method for simultaneous analysis of mevastatin and pravastatin in fermentation broth has been established and validated. Compounds were separated on aluminium foil TLC plates precoated with silica gel 60F254; the mobile phase was toluene-ethyl acetate-formic acid 3:2:1 (v/v), which gave compact bands of mevastatin and pravastatin (RF 0.48 ± 0.02 and 0.31 ± 0.02, respectively). Detection at 237 nm resulted in r = 0.992 and 0.995 for mevastatin and r = 0.995 and 0.994 for pravastatin, for peak height and peak area, respectively. The limits of detection and quantification for mevastatin were 20.1 and 60.8 ng per band, and for pravastatin 19.2 and 58.3 ng per band, respectively. The method enabled effective quantification of mevastatin and pravastatin in the fermentation broth of Actinomadura macra and can therefore be used as a stability-indicating method for routine analysis of these compounds during bioconversion.