Pakistan Atomic Energy Commission PAEC

Islamabad, Pakistan

Pakistan Atomic Energy Commission PAEC

Islamabad, Pakistan
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Aziz A.,Korean University of Science and Technology | Aziz A.,Korea Institute of Construction Technology | Aziz A.,Pakistan Atomic Energy Commission PAEC | Kim K.S.,Korean University of Science and Technology | Kim K.S.,Korea Institute of Construction Technology
Water, Air, and Soil Pollution | Year: 2017

Because of their adverse effects, such as their toxicity and carcinogenicity, volatile organic compounds (VOCs) are the most important and common pollutants produced by urbanization and industrial processes that contaminate air and water streams. VOCs, commonly originating from many industrial syntheses, and their derivatives, especially halogen, produce an unpleasant odor in the air when present in excess. All the issues related to VOCs make them a severe threat to whole ecosystems and environments as well as humans. Globally growing environmental awareness and knowledge have resulted in strict regulations to control VOC emissions into the air. It is necessary for each component of emitted VOCs to be controlled or removed from the air. NaZSM-5 and HZSM-5, having high ratios of SiO2/Al2O3 (50), which are necessary for good adsorbents of organics, were prepared. Characterization of the prepared materials was done by XRD, SEM, FTIR, N2 adsorption, NH3-TPD, 27Al-NMR, and TGA analysis. The adsorptive removal of VOCs from the air by Na-ZSM-5 and H-ZSM-5 was explored. These adsorption materials were tested with respect to the adsorption capacity, renewability, and selectivity for benzene, toluene, ethylbenzene, and xylene. The effects of the contact time, adsorbent dose, and initial concentration of pollutant on the adsorption process were also studied. Finally, the adsorption data were applied to Langmuir, Freundlich, and Temkin isotherms and two different kinetic models. © 2017, Springer International Publishing AG.

Aziz A.,Korean University of Science and Technology | Aziz A.,Korea Institute of Construction Technology | Aziz A.,Pakistan Atomic Energy Commission PAEC | Kim K.S.,Korean University of Science and Technology | Kim K.S.,Korea Institute of Construction Technology
Journal of Hazardous Materials | Year: 2017

In this work, the performance of benzene, toluene, ethylbenzene, and xylene (BTEX) removal and degradation from gas, air streams on UV pretreated Fe-ZSM-5 in a batch reactor at room temperature were studied. The Fe-ZSM-5 zeolite catalyst was prepared by hydrothermal reaction method. The influence of UV pre-irradiation time on the removal of BTEX were assessed by varying the time, ranging from 15 min to 60s min. Then, sustainability of the activation of the catalyst resulted by UV pretreatment was studied by the four-cycle experiment with one time UV irradiation and after each cycle irradiation followed by BTEX removal after every cycle respectively. The results of BTEX removal depicted that 30 min of UV pretreatment was sufficient for complete organics removal. The UV pretreatment effect on the catalytic oxidation and the stability of the catalyst were studied by modern instrumental techniques. The novelty of the process was the sustainable reuse of catalyst with persistent VOC removal, which works on the -adsorption-oxidation-regeneration-adsorption- cycle, which was confirmed by the characterization studies of the catalyst after four runs. The results revealed that the change in the structure, stability, morphology, and removal efficiency of the catalyst during the experiments was negligible. The VOC degradation mechanism studies showed that the oxidation occurs due to the formation of free radicals as well as hydroxyl ions, so named it heterogeneous photo-Fenton oxidation. The residual materials analysis showed the complete mineralization of VOC except small amount of acetone as oxidation product. Lastly, the kinetics of the VOC removal was studied. © 2017 Elsevier B.V.

Arif A.,National Institute for Biotechnology and Genetic Engineering NIBGE | Zafar Y.,Pakistan Atomic Energy Commission PAEC | Arif M.,National Institute for Biotechnology and Genetic Engineering NIBGE | Blumwald E.,University of California at Davis
Molecular Biotechnology | Year: 2013

An increasing volume of evidence indicating the mechanisms of drought tolerance of AVP1-overexpressing transgenic plants has been reported. In the present study, we are reporting the experiments conducted for the drought tolerance of AVP1 overexpressing plants and WT tobacco plants in three water regimes named as "fully watered," "less-watered," and "desiccated". Results suggest that AVP1 plants exhibited greater vigor and drought tolerance in quantitative terms i.e., increase in size and weight of shoots and capsules. AVP1 plants produced more seeds than WT across all three water regimes. The less-watered regime was found to produce the greatest contrast. AVP1 overexpression enhanced solute accumulation in vacuoles resulting in an increase in water retention and turgor of the cell. The ultrastructure study of AVP1 overexpressing cells and WT leaf cells revealed that AVP1 plants displayed more turgid and hyperosmotic cells than WT. Moreover, guard cells in the AVP1 plants exhibited thick cell walls, few vacuoles, and deep and close stomata, whereas WT plants showed larger vacuoles and relatively open stomata aperture with no significant difference in size and number of the cells per unit area. © 2012 Springer Science+Business Media, LLC.

Nisar J.,Uppsala University | Nisar J.,Pakistan Atomic Energy Commission PAEC | Topalian Z.,Uppsala University | De Sarkar A.,KTH Royal Institute of Technology | And 4 more authors.
ACS Applied Materials and Interfaces | Year: 2013

Fixation of SO2 molecules on anatase TiO2 surfaces with defects have been investigated by first-principles density functional theory (DFT) calculations and in situ Fourier transform infrared (FTIR) surface spectroscopy on porous TiO2 films. Intrinsic oxygen-vacancy defects, which are formed on TiO2(001) and TiO2(101) surfaces by ultraviolet (UV) light irradiation and at elevated temperatures, are found to be most effective in anchoring the SO2 gas molecules to the TiO 2 surfaces. Both TiO2(101) and TiO2(001) surfaces with oxygen vacancies are found to exhibit higher SO2 adsorption energies in the DFT calculations. The adsorption mechanism of SO 2 is explained on the basis of electronic structure, charge transfer between the molecule and the surface, and the oxidation state of the adsorbed molecule. The theoretical findings are corroborated by FTIR experiments. Moreover, the (001) surface with oxygen vacancies is found to bind SO 2 gas molecules more strongly, as compared to the (101) surface. Higher concentration of oxygen vacancies on the TiO2 surfaces is found to significantly increase the adsorption energy. The results shed new insight into the sensing properties of TiO2-based gas sensors. © 2013 American Chemical Society.

Wang B.,KTH Royal Institute of Technology | Kanhere P.D.,Nanyang Technological University | Chen Z.,Nanyang Technological University | Nisar J.,Pakistan Atomic Energy Commission PAEC | And 4 more authors.
Journal of Physical Chemistry C | Year: 2013

In this paper, we have employed DFT and HSE06 methods to study the doping effects on the NaTaO3 photocatalyst. N, S, C, and P monodoping and N-N, C-S, P-P, and N-P codoping have been studied. The redopants' formation energies have been calculated, and we find S monodoping is energetically more favorable than any other elemental doping. The mechanism of anion doping on the electronic properties of NaTaO3 is discussed. We find the band gap reduces significantly if we dope with anionic elements whose p orbital energy is higher than the O 2p orbitals. N and S can shift the valence band edge upward without losing the ability to split water into H2 and O2. Double-hole-mediated codoping can decrease the band gap significantly. On the basis of our calculations, codoping with N-N, C-S, and P-P could absorb visible light. However, they can only decompose water into H2 when the valence band edge is above the water oxidation level. © 2013 American Chemical Society.

Abbas Z.,Pakistan National Agricultural Research Center | Abbas Z.,National Institute for Genomics and Advanced Biotechnology NIGAB | Abbas Z.,National Institute for Biotechnology and Genetic Engineering NIBGE | Zafar Y.,Pakistan Atomic Energy Commission PAEC | And 2 more authors.
International Journal of Agriculture and Biology | Year: 2013

Insects have natural potential to develop resistance against chemical insecticides. Several resistance strategies have been suggested including biopesticides and use of two dissimilar toxins. Advances in molecular biology techniques have now allowed construction of chimeric proteins to delay the development of resistance in insect population, but still there are chances of developing resistance in insect population against them as these fusions are based on Bacillus thuringiensis (Bt) genes only, which have some homology in their amino acid sequences, having same mode of action and derived from same bacterial origin. In the present study ω-ACTX-Hv1a toxin gene (Hvt) as an insect calcium channel antagonist is fused with Bt cry1Ac to combine both strategies (biopesticides and two dissimilar toxins) and delay the resistance in insect population. The recombinant protein has been successfully expressed in prokaryotic system and was detected by SDS PAGE. Topical application of the 1.0 pmol purified recombinant protein to the thoracic region paralyzed and immobilized the Helicoverpa armigera and Spodoptera littoralis larvae within 2 h. 100% mortality was observed in insects after 24 h. The LD50 was found to be 4 and 2 pmol per gram of body weight for H. armigera and S. littoralis larvae, respectively. The present study clearly indicates that this recombinant protein is highly effective against agronomical important lepidopteron insects and is an excellent candidate for use as a biopesticides or expressed heterogeneously in agricultural crops to provide long lasting resistance to insect attacks. © 2013 Friends Science Publishers.

Mahmood S.,Pakistan Institute of Nuclear Science and Technology | Mahmood S.,Pakistan Institute of Engineering and Applied Sciences | Kanwal S.,Pakistan Institute of Engineering and Applied Sciences | Kanwal S.,Pakistan Atomic Energy Commission PAEC | And 2 more authors.
Physics of Plasmas | Year: 2012

Nonlinear electrostatic vortex structures in the rotating magnetized electron-positron-ion plasmas are investigated. The electrons and positrons are considered to be dynamic while ions are taken to be stationary to neutralize only plasma background. In linear limit, the dispersion relation for electrostatic wave in a rotating electron-positron-ion plasma is discussed for both local and nonlocal cases. It is also found that conditions for the existence of dipolar vortex structures are modified in the presence of stationary ions in a magnetized rotating electron-positron plasma. © 2012 American Institute of Physics.

Rafique J.,Harbin Institute of Technology | Rafique J.,Pakistan Atomic Energy Commission PAEC | Yu J.,Harbin Institute of Technology | Zha X.,Harbin Institute of Technology | Rafique K.,Pakistan Atomic Energy Commission PAEC
Bulletin of Materials Science | Year: 2010

Ultra thin and aligned carbon nanofibres (CNFs) have been fabricated by heat treatment from aligned polyacrylonitrile (PAN) nanofibre precursors prepared by electrospinning. The alignment of the precursor nanofibres was achieved by using a modified electrospinning set up developed recently, where a tip collector was used to collect and align the nanofibres. The average diameter of the aligned CNFs is about 80 nm. The stabilization and carbonization behaviour were studied mainly based on the randomly oriented PAN nanofibres. The effects of stabilization and carbonization temperatures, temperature-increasing rates, and with and without substrates on the morphology and structure of the CNFs were investigated. Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman spectroscopy were used to characterize the structure of the CNFs and thermogravimetric/ differential temperature analysis was used to evaluate the thermal behaviour of PAN nanofibres. © Indian Academy of Sciences.

Sadiq S.,COMSATS Institute of Information Technology | Sadiq S.,Pakistan National Agricultural Research Center | Imran M.,COMSATS Institute of Information Technology | Hassan M.N.,COMSATS Institute of Information Technology | And 4 more authors.
LWT - Food Science and Technology | Year: 2014

Antimicrobial behavior of lactic acid bacteria (LAB) has been explored since many years to assess their ability to produce bacteriocin, a natural preservative, to increase the shelf life of food. This study aims to characterize bacteriocin producing strains of lactic acid bacteria isolated from acidic to slightly acidic raw vegetables including tomato, bell pepper and green chili and to investigate their potential to inhibit food related bacteria. Among twenty nine LAB screened for antimicrobial activity, three exhibited antagonism against closely related bacterial isolates which was influenced by varying temperature and pH. They were identified up to strain level as Lactococcus lactis subsp. lactis TI-4, L. lactis subsp. lactis CE-2 and L. lactis subsp. lactis PI-2 based on 16S rRNA gene sequence. Their spectrum of inhibition was observed against food associated strains of Bacillus subtilis and Staphylococcus aureus. Moreover, L. lactis subsp. lactis PI-2 selected on the basis of higher antimicrobial activity was further evaluated for bacteriocin production which was detected as nisin A and nisin Z. These findings suggest the possible use of L. lactis strains of vegetable origin as protective cultures in slightly acidic as well as slightly alkaline food by the bio-preservative action of bacteriocins. © 2014 Elsevier Ltd.

Zafar A.Y.,National Institute for Genomics and Advanced Biotechnology | Zafar A.Y.,Pakistan Atomic Energy Commission PAEC | Iqbal J.,National Institute for Genomics and Advanced Biotechnology | Iqbal M.M.,National Institute for Genomics and Advanced Biotechnology | And 4 more authors.
Molecular Biotechnology | Year: 2011

Salinity and drought are main threat to agriculture productivity, to avoid further losses it is necessary to improve the genetic material of crops against these stresses In this present study, AtNHX1, a vacuolar type Na +/H + antiporter gene driven by 35S promoter was introduced into groundnut using Agrobacterium tumefaciens transformation system. The stable integration of the AtNHX1 gene was confirmed by polymerase chain reaction (PCR) and southern blot analysis. It was found that transgenic plants having AtNHX1 gene are more resistant to high concentration of salt and water deprivation than the wild type plants. Salt and proline level in the leaves of the transgenic plants were also much higher than that of wild type plants. The results showed that overexpression of AtNHX1 gene not only improved salt tolerance but also drought tolerance in transgenic groundnut. Our results suggest that these plants could be cultivated in salt and drought-affected soils. © Springer Science+Business Media, LLC 2011.

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