Pakistan Academy of science

Islamabad, Pakistan

Pakistan Academy of science

Islamabad, Pakistan
Time filter
Source Type

Bibi S.,University of PeshawarKhyber Pakhtunkhwa | Alam K.,University of PeshawarKhyber Pakhtunkhwa | Chishtie F.,Pakistan Academy of science | Bibi H.,University of PeshawarKhyber Pakhtunkhwa | Rahman S.,University of Karachi
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2017

Black Carbon (BC) mass concentration was measured continuously for every five-minute interval with ground-based Aethalometer at an urban site in Karachi for the period from 2006 to 2008. In this study, the temporal (diurnal, monthly and seasonal) variations of BC and its relationship with meteorological variables were analyzed. Monthly averaged concentrations of BC ranged from 2.2 to 12.5 µg/m3, with maximum in the month of January 2007 and minimum in the month of June 2006. BC showed higher concentrations during the months of January, February and November while lower during the months of May, June, July and August throughout the years. It also displayed comparatively high concentrations during winter and postmonsoon, while moderate during premonsoon and low during summer. Diurnal analysis of BC concentration showed sharp peaks between 07:00 and 09:00 LST and again around 22:00 during all the months. Moreover, the relationship between BC concentration and meteorological variables such as Temperature (Temp), Relative Humidity (RH), Wind Speed (WS), Visibility (VIS) and RainFall (RF) was found and it was observed that BC concentration showed an inverse relationship with all these meteorological variables. Finally, the analysis of the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) cluster trajectories revealed that almost all the clusters were originating from southwest of the study site. © 2017 Elsevier Ltd

Awan I.Z.,National Graduate School of Chemistry, Montpellier | Khan A.Q.,Pakistan Academy of science
Journal of the Chemical Society of Pakistan | Year: 2017

Summary: Precipitation from solid solutions and supersaturated solutions is a very important process as it plays an important role in the structure and properties of metals/alloys. This process is used widely in the metallurgical engineering to obtain desired mechanical properties. The phenomena under discussion has great practical significance, for they make possible the precipitation or age hardening of metals, an extremely important way of hardening of metals, especially in commercial strengthening of non-ferrous alloys, e.g. aluminum and magnesium alloys. This review discusses precipitation and its effects on hardening in solid solutions and saturated solid solutions.

Rahman L.,Quaid-i-Azam University | Shinwari Z.K.,Quaid-i-Azam University | Shinwari Z.K.,Pakistan Academy of science | Iqrar I.,Quaid-i-Azam University | Tanveer F.,Quaid-i-Azam University
Annals of Clinical Microbiology and Antimicrobials | Year: 2017

Background: Natural products of animals, plants and microbes are potential source of important chemical compounds, with diverse applications including therapeutics. Endophytic bacteria that are especially associated with medicinal plants presents a reservoir of therapeutic compounds. Fagonia indica has been recently investigated by numerous researchers because of its striking therapeutic potential especially in cancer. It is also reported that endophytes play a vital role in the biosynthesis of various metabolites; therefore we believe that endophytes associated with F. indica are of crucial importance in this regard. The present study aims successful isolation, molecular identification of endophytic bacteria and their screening for bioactive metabolites quantification and in vitro pharmacological activities. Methods: 16S rRNA gene sequencing was used for the identification of isolated endophytic bacteria. Methanolic extracts were evaluated for total phenolic contents (TPC), total flavonoids contents (TFC), DPPH free radical scavenging activity, reducing power and total anti-oxidant assays were performed. And also screened for antibacterial and antifungal activities by disc diffusion method and their MIC were calculated by broth dilution method using microplate reader. Further, standard protocols were followed for antileishmanial activity and protein kinase inhibition. Analysis and statistics were performed using SPSS, Table curve and Origin 8.5 for graphs. Results: Bacterial strains belonging to various genera (Bacillus, Enterobacter, Pantoea, Erwinia and Stenotrophomonas) were isolated and identified. Total phenolic contents and total flavonoids contents varies among all the bacterial extracts respectively in which Bacillus subtilis showed high phenolic contents 243μg/mg of gallic acid equivalents (GAE) and Stenotrophomonas maltophilia showed high flavonoids contents 15.9μg/mg quercitin equivalents (QA), total antioxidant capacity (TAC) 37.6μg/mg of extract, reducing power (RP) 206μg/mg of extract and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity with 98.7μg/mL IC50 value. Although all the extracts tested were active to inhibit growth of selected pathogenic microbes (bacteria and fungi), but significant antibacterial activity was observed against Klebsiella pneumonia and B. subtilis. An Enterobacter cloaca was active against Leishmania tropica with IC50 value of 1.4μg/mg extracts. B. subtilis and Bacillus tequilensis correspondingly exhibit significant protein kinase inhibition of 47±0.72 and 42±1.21mm bald zones, indicating anti-infective and antitumor potential. Conclusions: Our findings revealed that crude extracts of selected endophytic bacteria from F. indica possess excellent biological activities indicating their potential as an important source of antibiotics (antifungal, antibacterial) compounds. © 2017 The Author(s).

Bibi S.,University of PeshawarKhyber Pakhtunkhwa | Alam K.,University of PeshawarKhyber Pakhtunkhwa | Chishtie F.,Pakistan Academy of science | Bibi H.,University of PeshawarKhyber Pakhtunkhwa | Rahman S.,University of Karachi
Science of the Total Environment | Year: 2017

With observations of black carbon (BC) aerosol concentrations, optical and radiative properties were obtained over the urban city of Karachi during the period of March 2006–December 2008. BC concentrations were continuously measured using an Aethalometer, while optical and radiative properties were estimated through the Optical Properties of Aerosols and Clouds (OPAC) and Santa Barbra DISORT Atmospheric Radiative Transfer (SBDART) models, respectively. For the study period, the measured BC concentrations were higher during January, February and November, while lower during May, June, July and August. A maximum peak value was observed during January 2007 while the minimum value was observed during June 2006. The Short Wave (SW) BC Aerosol Radiative Forcing (ARF) both at Top of the Atmosphere (ToA) and within ATMOSphere (ATMOS) were positive during all the months, whereas negative SW BC ARF was found at the SurFaCe (SFC). Overall, SW BC ARF was higher during January, February and November, while relatively lower ARF was found during May, June, July and August. Conversely, the Long Wave (LW) BC ARF at ToA and SFC remained positive, whereas within ATMOS it shifted towards positive values (heating effect) during June–August. Finally, the net (SW + LW) BC ARF were found to be positive at ToA and in ATMOS, while negative at SFC. Moreover, a systematic increase in Atmospheric Heating Rate (AHR) was found during October to January. Additionally, we found highest correlation between Absorption Aerosol Optical Depth (AODabs) and SW BC ARF within ATMOS followed by SFC and ToA. Overall, the contribution of BC to the total ARF was found to greater than 84% for the whole observational period while contributing up to 93% during January 2007. © 2017 Elsevier B.V.

Ryan J.,International Center for Agricultural Research in the Dry Areas | Ibrikci H.,Cukurova University | Delgado A.,University of Seville | Torrent J.,University of Cordoba, Spain | And 2 more authors.
Advances in Agronomy | Year: 2012

Fertilizers have been largely responsible for the massive increases in world food production in the past half century that permitted accelerated global population growth to current unprecedented levels. Fertilizer use not only impacts crop yields but also affects animal production. While nitrogen (N) has been the main driver of such changes, phosphorus (P) also has a major role. Like N, the use of P fertilizers can have implications beyond the farmers' fields, if excessive amounts are applied. The past four decades have witnessed overuse of P fertilizers as well as animal manures in the intensive agricultures of some European countries and North America. Yet ironically in many areas of the world, notably Africa, agricultural output is largely constrained by low soil P in combination with little or no P fertilizer application. Rock phosphate is the global source of the raw material for P fertilizer. However, resources are finite, and therefore efficient and wise use is of paramount importance. The vast West Asia and North Africa (WANA) region is one where agricultural output is beset with major environmental constraints. Yet fertilizer use in the region is still in the incipient to early development stage, ironically in view of the fact that major deposits of exploitable rock phosphate are found in the region, mainly in Morocco and Tunisia. With the predominantly calcareous soils of the region being inherently low in available P, the main focus in the past few decades has been on promoting P use and its efficient management in rainfed and irrigated agriculture. In the 1960s and 1970s, virtually no fertilizer was used in the region, with rapid increases in N and to a lesser extent P since then. The sharp transition from low-input traditional agriculture to conventional modern agriculture has particular implications for efficient P fertilizer use from the economic and environmental standpoints. This review seeks to present a broad overview of P in countries of the WANA region, which varies considerably with respect to economic development and the level of agricultural research, education and extension. It presents the background global considerations with respect to P supplies and use, as well the agricultural context for the region, including climate and cropping systems; it draws heavily on research on soils and soil-P chemistry from Spain, which though technically excluded from WANA, has much in common with the Mediterranean region, and highlights P research from Pakistan at the eastern fringes of WANA. It highlights the discrepancy in P use between developed and developing countries such as those of WANA. The review to some extent builds on extensive research carried out in Syria by the International Center for Agricultural Research in the Dry Areas (ICARDA), with secondary emphasis on countries of the region, many of which collaborate closely with ICARDA. The review covers the past three decades, highlighting progress in field trials on fertilizer use with the region's main crops in relation to rainfall, cropping systems, soil test levels, and efforts to identify P-efficient genotypes and enhance soil P fertility with mycorrhizae. Despite the many isolated, uncoordinated, and often-overlapping, and indeed conflicting, research efforts that have taken place in the region, we have attempted to show a gradual progression in knowledge of P in relation to soils and crops. Developments with regard to P, in the overall framework of agricultural research, have contributed to increased output in the WANA region. Much of the documented research has contributed to the global information on soils of arid and semi-arid regions. Despite achievements in applied research, poorly developed technology transfer systems and weak analytical facilities remain as stumbling blocks to the widespread dissemination of the accumulated knowledge on P use to farmers. © 2012 Elsevier Inc.

Haque Q.,Pakistan Institute of Nuclear Science and Technology | Haque Q.,Pakistan Academy of science | Saleem H.,Pakistan Academy of science | Saleem H.,Institute of Space Technology
Physics of Plasmas | Year: 2015

The plasma density non-uniformity gives rise to the coupling of transverse magnetic electron drift vortex (MEDV) mode with the longitudinal perturbations in dissipative and non-dissipative electron plasmas. This coupling produces partially transverse and partially longitudinal low frequency instabilities in classical un-magnetized laser plasmas. The MEDV mode couples with the ion acoustic wave, when the ion dynamics is also included. Both the modes have frequencies of the same order of magnitude and couple to give rise to electromagnetic instabilities in un-magnetized plasmas. © 2015 AIP Publishing LLC.

Afzal I.,Quaid-i-Azam University | Shinwari Z.K.,Pakistan Academy of science | Iqrar I.,Quaid-i-Azam University
Pakistan Journal of Botany | Year: 2015

Endophytic bacteria can provide a useful alternative to synthetic fertilizers to improve plant growth. Wild plants are little investigated as a source of growth promoting endophytic bacteria for commercial application to crops. In present study, endophytic bacteria were isolated from Cannabis sativa L. (hemp) using two different methods to examine their ability to promote canola growth. Besides direct isolation from the roots, endophytic bacteria were also selectively isolated from the rhizosphere of C. sativa using canola. Under gnotobiotic conditions, six bacteria from the selective isolation significantly improved canola root growth, as compared to the two bacteria isolated from direct method. Overall, three isolates performed distinctly well, namely, Pantoea vagans MOSEL-t13, Pseudomonas geniculata MOSEL-tnc1, and Serratia marcescens MOSEL-w2. These bacteria tolerated high salt concentrations and promoted canola growth under salt stress. Further, the isolated bacteria possessed plant growth promoting traits like IAA production, phosphate solubilization, and siderophore production. Most isolates produced plant cell-wall degrading enzymes, cellulase and pectinase. Some isolates were also effective in hindering the growth of two phytopathogenic fungi in dual culture assay, and displayed chitinase and protease activity. Paenibacillus sp. MOSEL-w13 displayed the greatest antifungal activity among all the isolates. Present findings conclude that wild plants can be a good source for isolating beneficial microbes, and validates the employed selective isolation for improved isolation of plant-beneficial endophytic bacteria. © 2015, Pakistan Botanical Society. All rights reserved.

Hashmi A.H.,Institute of Biomedical and Genetic Engineering | Ahmad N.,Institute of Biomedical and Genetic Engineering | Riaz S.,Institute of Biomedical and Genetic Engineering | Ali L.,Institute of Biomedical and Genetic Engineering | And 4 more authors.
Genes and Immunity | Year: 2014

Recent discovery of single-nucleotide polymorphisms located in the upstream region of interleukin-28B (IL28B) has shown association with interferon (IFN) treatment response especially in hepatitis C virus (HCV) genotype 1-infected patients. Pakistan, being the country with second highest prevalence of HCV with predominantly 3a genotype infection, bears a significant disease burden. The present study was conducted to evaluate the effect of rs12979860 genotypes on treatment response in HCV-3a-infected patients. This study shows that the CC genotype is providing protection against infection to HCV. But once infected, the CC genotype patients show viral persistence following IFN therapy. The TT genotype is assisting the 3a patients in viral clearance after IFN treatment. To our knowledge, this is the first study showing rs12979860 genotype association with IFN response in Pakistani HCV-3a-infected patients. © 2014 Macmillan Publishers Limited.

Rafique E.,Pakistan National Agricultural Research Center | Rashid A.,Pakistan National Agricultural Research Center | Rashid A.,Pakistan Academy of science | Mahmood-ul-Hassan M.,Pakistan National Agricultural Research Center
Plant and Soil | Year: 2012

Aims: The cotton (Gossypium hirsutum L.)-wheat (Triticum aestivum L.) cropping system practised in >3 million ha of irrigated Aridisols in Pakistan is pivotal to its national economy and food security. Thus, the prevalent stagnation in its productivity is a matter of serious concern. Widespread deficiency of zinc (Zn) in these low organic matter alluvial calcareous soils is amongst the suspected constraints. Therefore, studying the impact of improved nutrient management strategies and crop residue recycling on crop productivity and soil Zn balances was thought imperative. Methods: A 5-year permanent layout field experiment was conducted on two predominant soil series of the cotton-wheat belt [i. e., Awagat (coarse loamy mixed, hyperthermic Fluventic Camborthid) and Shahpur (fine silty mixed, hyperthermic Fluventic Camborthid)] to compare the impact of (1) Farmers' fertilizer use (FFU); (2) Recommended fertilizer use (RFU); and (3) Integrated nutrient management (INM) on crop productivity and apparent soil Zn balances. The nutrient management strategies were compared with and without cotton-wheat residue recycling, in flat-bed sown and raised-bed sown cotton systems. Results: Under the FFU treatment, Zn deficiency occurred both in wheat and cotton. Overall lowest mean yields (Mg ha-1), obtained with FFU, were: seed cotton-Awagat, 2. 19; Shahpur, 2. 45; wheat grain-Awagat, 3. 03; Shahpur, 3. 94. Yield increases with RFU were: cotton, 24 % in Awagat and 18 % in Shahpur soil; wheat, 37 % in Awagat and 24 % in Shahpur soil (P ≤ 0. 05). With INM, crop yields were slightly higher than with RFU. Also, cotton yields were ~10 % greater on raised beds than on flat beds. Crop residue also increased yield of both crops, up to 10 %. Zinc uptake patterns of both crops were closely related to their yields. Fertilizer Zn use efficiency by the cotton-wheat system, in both soils, was quite low, i. e., 1. 78-2. 36 % of the annually applied 5 kg Zn ha-1. Thus, ~98 % of the applied Zn was retained (fixed) in the soils. Though Zn input from organic sources (i. e., crop residue and farm yard manure) was inadequate to meet crop requirements, Zn use efficiency from organic sources was much greater, i. e., 13-24 %. As Zn uptakes by the cropping system were quite low (i. e., 62-123 g Zn ha-1 by cotton; 74-170 g Zn ha-1 by wheat) compared with Zn inputs (i. e., 1. 12-1. 79 kg Zn ha-1 year-1), all nutrient management treatments, including FFU, resulted in positive apparent Zn balances in both soils. Conclusions: Thus, unlike nutrient balances for macronutrients, apparent Zn balances have little significance in predicting fertilizer Zn need of the cropping system. Despite positive soil Zn balances, even without using fertilizer Zn, prevalence of Zn deficiency in cotton and wheat crops may be attributed to high Zn fixation in calcareous soils rather than low total Zn content in the soils. In this scenario, soil testing and plant analysis remain the reliable approaches for diagnosing Zn deficiency problem. © 2012 Springer Science+Business Media B.V.

Shinwari Z.K.,Quaid-i-Azam University | Khalil A.T.,Quaid-i-Azam University | Nasim A.,Pakistan Academy of science
Archivum Immunologiae et Therapiae Experimentalis | Year: 2014

Over the last few decades biosecurity and biosafety have emerged as a prominent public health concern due to some high-profile accidents. Effective strategies to deal with the outbreak, whether deliberate or non-deliberate requires a multidisciplinary approach and coordinated decision-making by various state departments such as health, forensics, agriculture, environment, intelligence, law and enforcement, etc. In a dynamic global environment and the overwhelming asymmetric threats from the non-state actors, it is of utmost importance to understand the biosecurity issues and initiate a coordinated global effort to cope with biosecurity and biosafety breaches and develop an as effective response mechanism. An attractive choice for the terrorists, state enemies and non-state actors is the use of biological weapons. An unwanted incident may not only bring chaos to the people, but also can inflict severe economic damage industrially and locally as was in the notorious foot-and-mouth disease outbreak. Because of special geopolitical compulsion, Pakistan is one of the hot spots where special action needs to be taken. The current review focuses on the various approaches, technologies that can be used to alleviate the chances of biosafety and biosecurity incident and emphasizes the role of modern technology that can be used in this regard. © 2014 L. Hirszfeld Institute of Immunology and Experimental Therapy.

Loading Pakistan Academy of science collaborators
Loading Pakistan Academy of science collaborators