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Search Results: 1 - 10 of 1918 matches for " AJ Sami "
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Deletion of amino acid residues 33-46 in growth hormone alters the hydrophobicity of the molecule
AJ Sami
African Journal of Biotechnology , 2010,
Abstract: Growth hormone (GH) variants have been studied for the structure-function relationship of the molecule. The presence of a potential alternate splicing point in mRNA in bGH gene at exon 3, similar to hGH has been reported by workers. Early investigation on the characteristics of the chemistry of 20k oGH showed that the molecule was produced by site-directed mutagenesis by deleting amino acid residues 33-46 and the resultant DNA was expressed in E. coli under the control of lac promoter in pUC based plasmid. The mutant protein remained insoluble and did not refold. To investigate the effect of deletion on the chemistry of the molecule, computational biology tools were employed. The mutant with the deletion of amino acid residues 33-46, was designed and the model was visualized on computer. The structure of 20k bGH was compared with bGH and dissected for hydrogen bonds and hydrophobicity. Computational biology tools were helpful in elucidating the role of 33-46 amino acid residues domain in the chemistry of the molecule. Furthermore, it was revealed that removal of amino acid residues 33-46 which formed the hydrogen bonds involving Glu 33, Gln 46, Pro 38, Arg 42, Tyr 43,Ala 51, Thr 48, Asn 47, led to the formation of new hydrogen bonds between Thr 33, Tyr 144, Asn 32, Asn 32 and Ser and Asp 153. The removal of the amino acids 33-46 decreased the hydro-phobicity of the first helix of bGH molecule, as compared to 20k hGH, thus altering the solubility of the molecule, confirming the earlier reported results for ovine growth hormone with same deletion.
Production, purification and characterization of two recombinant DNA-derived N-terminal ovine growth hormone variants: oGH3 and oGH5
AJ Sami, OC Wallis, M Wallis
African Journal of Biotechnology , 2008,
Abstract: Two recombinant DNA-derived variants of ovine growth hormone were produced, purified, characterized and compared with the authentic pituitary derived GH. The variants oGH3 and oGH5 were isolated by differential centrifugation method and were purified after refolding by ion-exchange chromatography and gel filtration. Both the proteins showed single band on SDS-PAGE and had molecular weight and iso-electric point closer to authentic pituitary GH. The variants oGH3 and oGH5 were compared with the authentic pituitary derived GH in radio immuno assays, radio receptor assays and binding with the monoclonal antibodies OA 11 and OA12.
Preliminary studies on the production of endo-1,4-β–Dglucanases activity produced by Enterobacter cloacae
AJ Sami, M Awais, AR Shakoori
African Journal of Biotechnology , 2008,
Abstract: We report the production and characterization of endo-β-1, 4-glucanase from isolated phytopathogenic bacterium Enterobacter cloacae. The bacterium was grown on different carbon sources including carboxymethyl cellulose (CMC) and 2% Avicel, for the production of endo-1, 4-β –D-glucanases enzyme. E. cloacae produced maximum levels of cellulases after 96 h of fermentation. Higher levels of endoglucanases were produced when microbe was grown on CMC. Endo-1, 4- β-D- glucanase had optimum pH and temperature of 5.8 and 40°C. The enzyme was inactivated by calcium chloride and a reducing agent β-mercaptoethanol.
Isolation of cellulolytic activities from Tribolium castaneum (red flour beetle)
FU Rehman, M Aslam, MI Tariq, A Shaheen, AJ Sami, NH Naveed, AI Batool
African Journal of Biotechnology , 2009,
Abstract: Cellulolytic enzymes have immense potential to convert cellulosic biomass into useful products. Tribolium castaneum crude proteins were isolated to screen the cellulolytic activities. The activity was established by substrate-agar plate assay and confirmed by endoglucanase assay. Cellulolytic activity was further purified and characterized using the different chromatographic techniques and electrophoresis. Gel filtration chromatography showed the presence of multiple forms of enzyme activities with different molecular weights. Stability of enzyme activity was investigated at different temperatures and pH. Optimum pH for was found 4.8 at 40oC determined as optimum temperature. Gradually decreasing Enzyme activity remained half at 60oC. Zymography and SDS-PAGE showed the presence of multiple forms of endoglucanase activities (Cel I and Cel II) with molecular weight of 55 kDa and 35 kDa.
Performance of Galvanized Steel Reinforcement in Concrete in Sea and Dead Sea Water  [PDF]
Sami Masadeh
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.35006
Abstract: Steel reinforcements of 8 mm diameter and 24 cm length were cut from steel and after pickling treatment of all specimens. Steel reinforcements then were galvanized by hot dipping method. The measured coating thickness by thickness gage meter of zinc coat was in the range 8 - 11 μm. Bare steel samples were also used for comparison reasons. Each steel bar was inserted in a middle of a plastic tube with 4.5 cm diameter into which concrete was cast. After proper curing, specimens were immersed into 3.5% NaCl and Dead Sea water separately. Electrochemical impedance spectroscopy measurements were performed at different time intervals. Results showed that galvanized steel was corrosion resistant in sea water, and Dead Sea water over the test period.
Electrochemical Impedance Spectroscopy Of Epoxy-Coated Steel Exposed To Dead Sea Water  [PDF]
Sami Masadeh
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2005, DOI: 10.4236/jmmce.2005.42007
Abstract: Electrochemical impedance tests were applied to steel specimens which were coated by epoxy and tested after immersion in Dead Sea water for different periods at room temperature and at 50C. Results taken from Nyquist and Bode plots and as were analyzed by means of software provided with the instrument. Results were presented as the values of capacitance and resistance (Cdl and Rct). Results show that degradation occurred after immersion in the test solution, and were more severe at higher temperature. Specimens were examined under scanning electron microscope, and micrographs showed clear rupture and degradation in epoxy coatings.
The Effect of Added Carbon Black to Concrete Mix on Corrosion of Steel in Concrete  [PDF]
Sami Masadeh
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2015, DOI: 10.4236/jmmce.2015.34029
Abstract: The effect of added carbon black to concrete mix on corrosion of steel reinforcement was studied. This was achieved by inserting steel bars in different concrete mixes containing 0.1, 0.2, 0.3, 0.4, and 0.5, carbon black/cement. Samples were cured, immersed in 3.5% chloride solution for 6 months. Chloride permeability and corrosion rates were measured. Tests showed that corrosion rate and chloride ions penetration decreased with increased carbon black content. This was expressed due to filling effect of very fine particles of carbon black and was in the order less than 250 nm.
Radio Wave Propagation Characteristics in FMCW Radar  [PDF]
Ghada M. SAMI
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2009, DOI: 10.4236/jemaa.2009.14042
Abstract: FMCW Radar (Frequency Modulated Continuous Wave Radar) is used for various purposes, such as atmospheric Remote Sensing, inter-vehicle ranging, etc. FMCW radar systems are usually very compact, relatively cheap in purchase as well as in daily use, and consume little power. In this paper, FMCW radar determines a target range by measuring the beat frequency between a transmitted signal and the received signal from the target, and Combines between PO and radar single. The approach based on frequency domain physical optics for the scattering estimation and the linear system modeling for the estimation of time domain response, and FMCW Radar signal processing.
Multidimensional electrostatic energy and classical renormalization  [PDF]
Sami M. ALJaber
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.27095
Abstract: Recent interest in problems in higher space di mensions is becoming increasingly important and attracted the attention of many investigators in variety of fields in physics. In this paper, the electrostatic energy of two geometries (a charged spherical shell and a nonconducting sphere) is calculated in higher space dimension, N. It is shown that as the space dimension increases, up to N = 9, the electrostatic energy of the two geometries decreases and beyond N = 9 it increases. Furthermore, we discuss a simple example which illustrates classical renormalization in electrostatics in higher dimensions.
Energy and Momentum Considerations in an Ideal Solenoid  [PDF]
Sami Mohammad AL- Jaber
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.23024
Abstract: The electromagnetic linear momentum and the energy balance in an infinite solenoid with a time-dependant current are examined. We show that the electromagnetic linear momentum density and its associated force density are balanced by the hidden momentum density and its associated hidden force density respectively. We also show that exactly half the energy delivered by the power supply appears as stored magnetic energy inside the solenoid. The other half is lost against the induced electromotive force that appears in the windings of the solenoid during the time through which the current is building up towards its final value. This energy loss, which is found in other analogue situations, is necessary to transfer the system from an initial non-equilibrium state to a final equilibrium one.
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