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Monitoring of Pesticide Residues in Commonly Used Fruits in Hyderabad Region, Pakistan  [PDF]
Yawar Latif, Syed Tufail Hussain Sherazi, Muhammad Iqbal Bhanger
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.228123
Abstract: A market based survey was carried out to evaluate the level of 26 pesticides in some commonly used fruits in Hyderabad region, Pakistan. Gas chromatography coupled with micro electron capture detector was used to assess the levels of pesticide residues. Gas chromatography-mass spectrometry (GC-MS) was also applied for the confirmation of results. Out of total 131 analyzed samples, 53 (40%) were found contaminated with pesticide residues while only 3 (2%) samples were exceeded the MRLs of some pesticides. Chlorpyrifos and dieldrin were detected in almost all analyzed samples. Residues of chlorpyrifos (1256 µg/kg) and endosulfan sulfate (1236 µg/kg) were found higher in orange and apple samples, respectively. The findings of this study provided important data about contamination of pesticide residue in some fruits sold in Hyderabad, Pakistan, and recommended that monitoring studies should be expanded to other fruits grown in different agro climatic regions, which may serve as basis for future policy about the standards and quality control of pesticides.
Evaluation of Pesticide Residues in Human Blood Samples of Agro Professionals and Non-Agro Professionals  [PDF]
Yawar Latif, Syed Tufail Hussain Sherazi, Muhammad Iqbal Bhanger, Shafi Nizamani
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.38077
Abstract: The aim of the present study was to evaluate the pesticide residues in human blood samples of volunteers related to Hyderabad and Mirpurkhas districts, Pakistan. The volunteers of both districts were divided into four groups on the basis of their exposure period to pesticides i.e. Group A-5 to 9 years, Group B-10 to 14 years, Group C-15 to19 years and Group D-above 20 years. Out of total 188 volunteers, 145 volunteers (77.1%) were agro–professionals and 43 volun- teers (32.9%) were non–agro professionals. Chlorpyrifos, endosulfan, 1, 1, 1-trichloro-2, 2-bis (p-chorophenyl) ethane (p,p'-DDT) and parathion residues were detected in many samples. The predominant pesticides found in blood samples of both district volunteers were chlorpyrifos (with highest mean concentration of 0.37 mg kg-1 in the D group of Mirpurkhas) and endosulfan (with highest mean concentration of 0.30 mg kg-1 in the D group of Hyderabad). The quantity of pesticide residues detected in some blood samples of agro-professionals were found to be at the alarming level.
Yawar Baig,Hamid Latif Siddiqui,Waseeq Ahmad Siddiqui,Ghulam Mustafa
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810035385
Abstract: In the title compound, C14H10Cl2N2O2, the dihedral angle between the two aromatic rings is 17.39 (4)°. An intramolecular O—H...O hydrogen bond forms a six-membered R(6)11 ring motif. In the crystal structure, intermolecular N—H...O and O—H...O hydrogen-bonding interactions occur.
Assessment of Pesticide Residues in Some Fruits Using Gas Chromatography Coupled with Micro Electron Capture Detector
Yawar Latif,S. T. H. Sherazi,M. I. Bhanger
Pakistan Journal of Analytical and Environmental Chemistry , 2011,
Abstract: A very sensitive analytical method for the determination of 26 pesticides in some fruits based on solid phase extraction (SPE) cleanup was developed using gas chromatography (GC) coupled with micro electron capture detector (μECD). The identity of the pesticides was confirmed by gas chromatography mass spectroscopy (GC-MS) using selected ion monitoring (SIM) mode. Ethyl acetate was used as a solvent for the extraction of pesticide residues with assistance of sonication. For cleanup an octadecyl, C18 SPE column was used. A linear response of μECD was observed for all pesticides with good correlation coefficients (>0.9992). Proposed method was successfully applied for the determination of pesticide residues in the orange, apple, and grape fruits. Average recoveries achieved for all of the pesticides at fortification levels of 0.05, 1.0 and 2.0 μg g-1 in analyzed fruits were above 90% with relative standard deviations (RSD) less than 6
Comment on "Dielectric screening and plasmons in AA-stacked bilayer graphene"
Yawar Mohammadi
Physics , 2014,
Abstract: In this comment we show that some equations and results of the paper titled "Dielectric screening and plasmons in AA-stacked bilayer graphene" are not correct. Furthermore, we present our results which seems to be more correct.
Charge screening and carrier transport in AA-stacked bilayer graphene: tuning via a perpendicular electric field
Yawar Mohammadi
Physics , 2014, DOI: 10.1016/j.ssc.2014.10.032
Abstract: The static dielectric function in AA-stacked bilayer graphene (BLG), subjected to an electric field applied perpendicular to layers, is calculated analytically within the random phase approximation (RPA). This result is used to calculate the screened Coulomb interaction and the electrical conductivity. The screened Coulomb interaction, which here can be tuned by the perpendicular electric field, shows a power-law decay as $1/(\gamma^{2}+V^2)$ at long-distance limit where $V$ and $\gamma$ are the electrical potential and the inter-layer hopping energy respectively, indicating that the Coulomb interaction is suppressed at high perpendicular electric fields. Furthermore, Our results for the effect of the short-range and the long-range (Coulomb) scattering on the electrical conductivity show that the shot-range scattering yields a constant electrical conductivity which is not affected by the perpendicular electric filed. While the electrical conductivity limited by the Coulomb scattering is enhanced by the perpendicular electric field and increases linearly in $V^2$ at small $V$ with a finite value at $V=0$, indicating that we can tune the electrical conductivity in AA-stacked BLG by applying a perpendicular electric field.
RKKY interaction in bilayer graphene
Yawar Mohammadi,Rostam Moradian
Physics , 2014, DOI: 10.1016/j.jmmm.2015.07.094
Abstract: We study the RKKY interaction between two magnetic impurities located on same layer (intralayer case) or on different layers (interlayer case) in undoped bilayer graphene in the four-bands model, by directly calculating the Green functions in the eigenvalues and eigenvectors representation. Our results show that both intra- and interlayer RKKY interactions between two magnetic impurities located on same (opposite) sublattice are always ferromagnetic (antiferromagnetic). Furthermore we find unusual long-distance decay of the RKKY interaction in BLG. The intralyer RKKY interactions between two magnetic impurities located on same sublattice, $J^{A_{n}A_{n}}(\mathbf{R})$ and $J^{B_{n}B_{n}}(\mathbf{R)}$, decay closely as $1/R^{6}$ and $1/R^{2}$ at large impurity distances respectively, but when they are located on opposite sublattices the RKKY interactions exhibit $1/R^{4}$ decays approximately. In the interlayer case, the RKKY interactions between two magnetic impurities located on same sublattice show a decay close to $1/R^{4}$ at large impurity distances, but if two magnetic impurities be on opposite sublattices the RKKY interactions, $J^{A_{1}B_{2}}(\mathbf{R})$ and $J^{B_{1}A_{2}}(\mathbf{R)}$, decay closely as $1/R^{6}$ and $1/R^{2}$ respectively. Both intra- and interlayer RKKY interactions have anisotropic oscillatory factors which for intralayer case is equal to that for single layer graphene. Our results at weak and strong interlayer coupling limits reduce to the RKKY interaction of SLG and that of BLG in the two-bands approximation respectively.
Magnetism of an adatom on biased AA-stacked bilayer graphene
Yawar Mohammadi,Rostam Moradian
Physics , 2014, DOI: 10.1016/j.physb.2014.02.010
Abstract: We study magnetism of an adatom adsorbed on AA-stacked bilayer graphene (BLG) in both unbiased and biased cases, using the Anderson impurity model. We find different magnetic phase diagrams for the adatom, depending on the energy level of the adatom, which varies from the magnetic phase diagram of adatom in normal metals to that in graphene. This is due to the individual energy dependence of the density of states (DOS) of AA-stacked BLG and anomalous broadening of the adatom energy level. Furthermore we investigate the effect of a bias voltage on DOS of AA-stacked and show that the magnetization of the adatom can be controlled by applying the bias voltage. This allows for possibility of using AA-stacked BLG in spintronic devices.
Local moment formation in bilayer graphene
Yawar Mohammadi,Rostam Moradian
Physics , 2014, DOI: 10.1016/j.ssc.2013.10.021
Abstract: The local properties of bilayer graphene (BLG) due to the spatial inhomogeneity of its sublattices are of interest. We apply Anderson impurity model to consider the local moment formation on a magnetic impurity which could be adsorbed on different sublattices of BLG. We find different features for the impurity magnetization when it is adsorbed A and B sublattices. The impurity adsorbed on A sublattice can magnetize even when the impurity level is above the Fermi level and the on-site coulomb energy is very small. But when the impurity is adsorbed on B sublattice the magnetization is possible for limited values of the impurity level and the on-site coulomb energy. This is due to different local density of the low energy states at A and B sublattices which originates from their spatial inhomogeneity. Also we show that electrical controlling the magnetization of adatoms besides it's inhomogeneity in BLG allow for possibility of using BLG in spintronic devices with higher potential than graphene.
Genesis of Polio Vaccination Hindrance Syndrome in Pakistani Society, Religio-Medical Aspects  [PDF]
Sadia Fida Ullah, Farzana Ahmad Deen, Yawar Hussain
Open Journal of Social Sciences (JSS) , 2016, DOI: 10.4236/jss.2016.43015
Abstract: Polio vaccination in Pakistan has received strong reaction from the society. Many reasons have been documented in literature to explain the causes of this issue. The present study is focused on the analysis of anatomy of genesis of Polio Vaccination Hindrance Syndrome (PVHS) in the light of Quranic Verses, Hadiths (saying of Prophet) and their interpretations done by the Muslim clerics at weekly sermons (Khotbat). Along with religious explanation, the medical aspects of vaccination are also taken under consideration. It is concluded from this analysis that Islam does not resist from Polio Vaccination and related medication. The real problem lies in the perception of vaccination as an attempt to genocide Muslims, coupled with lack of interests in international agencies.
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