Showing papers by "Nasser A.M. Barakat published in 2011"

Synthesis and film formation of iron–cobalt nanofibers encapsulated in graphite shell: magnetic, electric and optical properties study

Abstract: Novel characteristics for the FexCoy alloys have been obtained when these compounds were synthesized in the form of nanofibers encapsulated in a graphite shell. The prepared nanofibers reveal good semiconducting features as a thin film from the prepared nanofibers supported on a graphite disk and could be utilized as a diode with good rectifying behaviour. Magnetic properties study showed that the introduced nanofibers are magnetically clean as very low remanent magnetizations were detected; moreover the saturation magnetization is a temperature-independent property. Optical properties study indicated that these nanofibers have band gap energies of 4.73 and 5.43 eV. FexCoy bimetallic alloys could be produced in the form of nanofibers encapsulated in a graphite shell by calcination of electrospun nanofiber mats composed of poly(vinyl alcohol), ferrous acetate and cobalt acetate tetrahydrate in an argon atmosphere at 750 °C. The composition of the nanofibers could be adjusted by controlling the concentration of the original electrospun solution; two formulations have been prepared: FeCo and FeCo2.7. Transmission electron microscopy indicated that the thickness of the graphite shell enveloping the obtained nanofibers is ∼10 nm. A graphite disk possessing on its surface a well attached thin film from the introduced nanofibers could be successfully prepared when a diskette made of poly(acrylonitrile) was used as a collector during the electrospinning process. The introduced methodology is effective, simple and can be exploited to produce different metallic alloys nanofibers.

Improvement of plants salt tolerance by exogenous application of amino acids

Abstract: The present work has been performed to study the growth and metabolic activities of maize and broad bean plants which are shown to have a degree of sensitivity to salinity and to determine the role of amino acids proline or phenylalanine in increasing the salt tolerance of theses plants. Dry mass, water content, leaf area and photosynthetic pigment of maize and broad bean plants decreased with increasing salinity. These changes were accompanied with a drop in the contents of soluble sugars, soluble proteins and amino acids. This was accompanied by a marked increase in the proline content. When maize and broad bean plants sprayed with proline or phenylalanine the opposite effect was occurred, saccharides as well as proteins progressively increased at all sanitization levels and proline concentration significantly declined. Salinity significantly increased the sodium content in both shoots and roots of maize and broad bean plants, while a decline in the accumulation of K+, Ca++, Mg++and P was observed. Amino acids treatments markedly altered the selectivity of Na+, K+, Ca++ and P in both maize and broad bean plants. Spraying with any of either proline or phenylalanine restricted Na+ uptake and enhanced the uptake of K+, K+/Na+ ratio, Ca++ and P selectivity in maize and broad bean plants. Key words: Proline, phenylalanine, spraying, salinity, maize, broad bean.

Oxidative stress markers and antioxidant potential of wheat treated with phytohormones under salinity stress

Abstract: The interactive effects 0.5 mM indole acetic acid or 0.1 mM of salicylic acid as shoot spraying on NaCl wheat stressed plant organs (spike, shoot and root) grown in pot experiment under different salinity levels (0, 50, 100, 150 and 200 mM NaCl) were studied. The antioxidant enzymes as catalase, peroxidase and ascorbate peroxidase, photosynthetic pigments, reducing sugar, proteins, amino acids, and proline contents in spike, shoot and root of salinity stressed plants were the most affected parameters specially at high salinity levels (150-200 mM NaCl).Treatments with 0.5 mM indole acetic acid or 0.1 mM of salicylic acid as shoot spraying on NaCl wheat stressed plant organs mitigated the harmful effect of NaCl. To conclude the phytohormone indole acetic acid or salicylic acid improved salt tolerance in stressed wheat by significantly activated catalase, peroxidase, and ascorbate peroxidase, increased photosynthetic pigments and enhancing the accumulation of nontoxic metabolites (sugars, proteins, amino acid and free proline) as a protective adaptation mechanism in different wheat organs. However, the magnitude of increase was more pronounced in salicylic acid treated plants than in indole acetic acid treated ones, and the spike was more accumulator organ of non toxic metabolites compared to shoot and root. Thus salicylic acid and/or indole acetic acid treatments prevents the deleterious effects of salinity stressed wheat and could be adopted as a potential growth regulator or antioxidant to improve growth particularly under moderate NaCl salinity levels, wheat plant respond positively to SA foliar application than IAA application.

Influences of Silver-Doping on the Crystal Structure, Morphology and Photocatalytic Activity of TiO2 Nanofibers

Abstract: Doping of titanium dioxide nanofibers by silver nanoparticles revealed distinct improvement in the photocatalytic activity; however other influences have not been investigated. In this work, effect of sliver-doping on the crystal structure, the nanofibrous morphology as well as the photocatalytic activity of titanium oxide nanofibers has been studied. Silver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600℃. The results affirmed formation of silver-doped TiO2 nanofibers composed of anatase and rutile when the silver nitrate content in the original electrospun solution was more than 3 wt%. The rutile phase content was directly proportional with the AgNO3 concentration in the electrospun solution. Negative impact of the silver-doping on the nanofibrous morphology was observed as increase the silver content caused to decrease the aspect ratio, i.e. producing nanorods rather nanofibers. However, silver-doping leads to modify the surface roughness. Study of the photocatalytic degradation of methylene blue dye clarified that increase the silver content strongly enhances the dye oxidation process.

Fabrication of Mineralized Collagen from Bovine Waste Materials by Hydrothermal Method as Promised Biomaterials

Abstract: In the present study, we aimed to produce mineralized-collagen by hydrothermal process. A simple method not depending on additional foreign chemicals has been employed to isolate the mineralized-collagen fibers from bovine waste. The process of extraction involves the use of hydrothermal method from available bovine bones. The structural and morphological properties of the collagen fibers were characterized by using scanning electron microscopy and transmission electron microscopy. These results indicated well received collagen fibers, having a diameter less than 1 μm and with established mineral content in the individual fibers. The X-ray diffraction showed the crystalline feature of the obtained nano-compounds. The thermo gravimetric analysis was used to differentiate between the collagen and mineral parts of obtained product. Overall, the results generously indicated production of well received collagen fibers from bovine bones.

Polymer nanofiber-templated fabrication and characterization of gallium oxide nanofibers consisting of granular nanoparticles

Abstract: Gallium oxide (β-Ga2O3) is an interesting semiconductor that has a wide bandgap and can be used as an optoelectronic material in flat-panel displays, solar energy conversion devices and optical limiters for UV light. However, it is difficult to fabricate and process Ga2O3 nanofibers for actual optoelectronic applications. When the excellent processability of polymeric materials is introduced into the inorganic nanofiber fabrication process, this limitation can be easily overcome. The aim of the research reported was to prepare granular Ga2O3 nanofibers utilizing an electrospun polyacrylonitrile nanofiber template combined with sol-gel technology. Ga2O3 nanofibers were successfully fabricated by electrospinning a solution of polyacrylonitrile mixed with gallium nitrate and subsequent calcination. The surface and bulk morphologies of the calcined nanofibers investigated using field-emission scanning electron microscopy and transmission electron microscopy (TEM) indicated that Ga2O3 nanofibers were constructed by the fusion of gallium oxide nanoparticles. TEM bright-field images combined with selected-area electron diffraction indicated that the average diameter of the Ga2O3 nanofibers produced was ca 55 nm and the crystalline structure was β-Ga2O3 with a monoclinic unit cell. Furthermore, the photoluminescence spectrum of the Ga2O3 nanofibers exhibited two strong green emission peaks and one UV emission peak. Copyright © 2010 Society of Chemical Industry

Photocatalytic properties of silver nanoparticles decorated nanobranched TiO2 nanofibers.

Abstract: In this study, nanobranched TiO2 nanofibers and silver loaded nanobranched TiO2 nanofibers were prepared by electrospinning technique followed by TiCl4 aqueous solution treatment and silver photodeposition method. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to investigate the morphology of the products. X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) were conducted on the samples to study their chemical composition as well as crystallographic structure. The photocatalytic activities of these produced nanofibers were examined with two organic dyes, methylene blue and methyl orange, under ultraviolet (UV) light irradiation. The effect of nanobranches and silver modification on TiO2 nanofibers was revealed in the photocatalysis process. The photocatalytic degradation rates of silver loaded on nanobranched TiO2 nanofibers were 1.6 and 1.7 times as that of pure TiO2 nanofibers in the presence of methylene blue and methyl orange, respectively, which indicated silver nanoparticles combined nanobranches modified on the surface of TiO2 nanofibers could enhance the photocatalytic ability.

Ameliorative effects of Ca 2+ on the growth, metabolism, cationic status and cell wall degrading enzymes of induced salinity stress Vicia faba L.

Abstract: Vicia faba L. Plant was grown in a pot experiment to study the positive role of CaCl 2 on NaCl induced stress in terms of growth parameters, metabolic, cation contents and cell wall degrading enzymes in different plant organs. The salinity treatments were having an osmotic potential of (0.0; -0.23;-0.46; -0.92 and -1.15 MPa), respectively. A hundred mL of 10 mM CaCl 2 were added to the previous concentrations and harvested after 11 weeks old. The data revealed that, NaCl treatments reduced the growth parameters; which most sensitive in root than shoot. Organic cytosolutes were much higher in root than shoot organ except for protein accumulation. The amount of inorganic cytosolutes (Na + and Ca 2+ ) in general increased markedly in shoot than root and vice versa for K + and Mg 2+ . CaCl 2 treatment alone induces these parameters than control one. Mixed salts of NaCL and CaCl 2 positively improve the aforementioned parameters with varying degrees depending on the organs. While root seems to be the more sensitive organ for growth parameters measured, it also seems most accumulator organ than shoot for many metabolites. For the ionic contents, shoot and root varies between the mono and divalent cations. Cell wall degrading enzymes significantly and progressively increased as salinity level of treated plants increased. However, CaCl 2 treatments induced a significant reduction in the activity of these enzymes when compared with their respective NaCL treatments. The ameliorative percentage due to calcium application of stressed faba bean on growth parameters ranges from 17.53 to 79.55 %; for metabolites from 8.69 to 194.91; for ionic status from 9.94 to 56.67 %, and for cell wall degrading enzymes from 16.76 to 39.15 %. These data leads to strongly recommend adding CaCl 2 to saline environment to decrease the deleterious effects of salinity.

Nanobiotechnology approach to fabricate polycaprolactone nanofibers containing solid titanium nanoparticles as future implant materials

Abstract: In this study, a good combination of electrospun poly(caprolactone) nanofibers incorporated with high purity titanium nanoparticles is introduced for hard tissue engineering applications. A simple approach to utilize the colloidal properties of poly(caprolactone) and titanium nanoparticles are exploited to form nanofibers by the simple electrospinning process. The prepared colloidal solutions were characterized using dynamic light scattering and electrophoratic light scattering which indicated unimodal size distribution and negative zeta potential. To investigate the bioactivity of the resultant nanofiber mats, they were incubated in simulated body fluid at 37 °C for 10 days. Field emission scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy indicated that incorporation of titanium strongly activates precipitation of the apatite-like materials from the utilized simulated body fluid. Moreover, in-vivo experiments using experimental dogs revealed that nanofibers ca...

Novel Biodegradable Natural plant Material Reinforced Thermosetting Polymer Composites/Polyester

Abstract: In this study, waste vegetal particles (date palm seed particle (DPSp)) were utilized to improve the mechanical properties of unsaturated polyester (USP). The proposed reinforcing particles were utilized with and without an alkali treatment process. The virgin and treated DPSp particles were characterized by TGA, XRD, FTIR, and SEM analyses. The results demonstrated that the alkali treatment has a large effect on the characteristics of the DPSp. The particles were added to UPS to form composites with DPSp weight percentages of 10, 20, and 40%. Compression and hardness properties of the prepared composites were evaluated. Moreover, their moisture absorption ability was investigated. In addition, the water absorption was direct1y proportion to the DPSp content with relative increases of DPSp.