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Metal resistance and uptake by Trichosporon asahii and Pichia kudriavzevii isolated from industrial effluents

Ilyas S., Rehman A.

Archives of Environmental Protection

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2018

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Vol. 44, no. 3

77--84

EN

Metal-resistant yeast strains, Trichosporon asahii and Pichia kudriavzevii, were grown-well onto YPD medium at 37°C (pH 6) and 30°C (pH 7), respectively. Tolerance values determined in T. asahii were 35 mM (Pb), 33 mM (Cu), 30 mM (As) and 10 mM (Cd) while P. kudriavzevii resisted up to 31 mM (Pb), 27 mM (Cu), 15 mM (Cd) and 12 mM (As). Yeasts grown in Minimal Salt Medium (MSM) were treated separately with metal challenge (100 mg/L) for 2 days. T. asahii showed elevated glutathione (GSH) level with Cd (83.06), As (81.87), Pb (66.88) and Cu (56.19) mM/g which was 70 (Cu), 69.87 (Pb), 56.47 (As) and 52.76 (Cd) in P. kudriavzevii as compared to the control. The glutathione (GSH): glutathione disulfi de (GSSG) ratio was decreased with all treated heavy-metals except Cd in T. asahii and increased with Cu and Pb in P. kudriavzevii. T. asahii could remove 78% (Cd), 72% (As), 85% (Cu) and 94.5% (Pb) from the medium after 12 days while was able to uptake 44.8, 41, 62 and 72 mg/g Cd, As, Cu and Pb, respectively. Likewise, P. kudriavzevii was able to remove 61% (Cd), 62% (As), 61% (Cu) and 87% (Pb) after 12 days of incubation and also showed capacity to uptake 36.8, 48, 40 and 57 mg/g Cd, As, Cu and Pb, respectively. Total protein profi ling of yeasts revealed marked differences in banding pattern due to increased oxidation under metal stressed conditions. High metal uptake ability makes T. asahii and P. kudriavzevii potential candidates to remove metals from the environment.

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Single-Step Antimicrobial And Moisture Management Finishing Of Pc Fabric Using Zno Nanoparticles

Ashraf M., Siyal M., Nazir A., Rehman A.

Autex Research Journal

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2017

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Vol. 17, no. 3

259--262

EN

Functionalization of textile fabrics with metal oxide nanoparticles can be used to add antibacterial and moisture management properties to them. Current work focuses on the development of these properties on polyester/cotton woven fabrics by treating them with zinc oxide nanoparticles for workwear and sportswear applications. Zinc oxide nanoparticles, prepared by sol-gel method, were applied on fabric samples, which were then tested for antibacterial and moisture management properties using standard test methods AATCC 147 with Staphylococcus aureus and AATCC 195, respectively. It was found that application of ZnO nanoparticles improved both these properties with smaller particle imparting larger effects on both of them.

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Parametric optimization of rice bran oil extraction using response surface methodology

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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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.

4

Stagnation point flow of Eyring Powell fluid in a vertical cylinder with heat transfer

Rehman A., Achakzai S., Nadeem S., Iqbal S.

Journal of Power Technologies

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2016

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Vol. 96, nr 1

57--62

EN

In this paper an analysis is carried out to examine the effects of natural convection heat transfer for steady boundary layer flow of an Eyring Powell fluid flowing through a vertical circular cylinder. The governing partial differential equations along with the boundary conditions are reduced to dimensionless form by using the boundary layer approximation and applying suitable similarity transformations. The resulting nonlinear coupled system of ordinary differential equations subject to the appropriate boundary conditions is solved using the analytic technique homotopy analysis method (HAM). The effects of the physical parameters on the flow and heat transfer characteristics are presented. The behavior of skinfriction coefficient and Nusselt numbers are also studied for different parameters.

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Stagnation flow of couple stress nanofluid over an exponentially stretching sheet through a porous medium

Rehman A., Nadeem S., Malik M. Y.

Journal of Power Technologies

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2013

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Vol. 93, nr 2

122--132

EN

The present investigation is carried for the problem of boundary layer stagnation point flow and heat transfer of couple stress fluid containing nanoparticles and flowing over an exponentially stretching surface in a porous medium. The governing equations of couple stress fluid model for velocity, temperature and nanoparticle profiles are given under boundary layer approach. The nonlinear partial differential equations are simplified by using similar transformations. The analytical solutions of simplified equations are found with the help of homotopy analysis method. The convergence of the HAM solutions has been discussed by plotting - curves and also through homotopy pade approximation. The physical features of pertinent parameters have been discussed through graphs.

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Rayleigh waves speed in transversely isotropic material

Rehman A., Khan A., Ali A.

Engineering Transactions

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2006

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Vol. 54, iss. 4

323-328

EN

Rayleigh wave speed in transversely isotropic material is studied. A very simple technique is adopted to solve the secular equation. Speed in some transversely isotropic materials is calculated.