Elyas Sadeq AlAghbari | Taiz University (original) (raw)
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Papers by Elyas Sadeq AlAghbari
Low-crystalline polypropylene films (PP) were irradiated with different doses of γ-radiation (0, ... more Low-crystalline polypropylene films (PP) were irradiated with different doses of γ-radiation (0, 1, 2.5, 5, 7.5 and 10 Mrad). Differential scanning calorimetry, (DSC), wide-angle X-ray diffraction (WAXD) and FT-IR measurements were used to study the effects of γ-radiation on crystallinity, crystalline structure and thermal changes. It was found that crystalline structure, thermal behavior and crystallinity significantly changed with γ-irradiation. The crystallinity changes mainly depend on γ-irradiation dose, chain scission and crosslinking. The rise in crystallinity was found to be limited and related to chain scission. However, the reduction was accompanied by formation of crosslinking.
A novel visible– light driven photocatalyst, BIMNVOX.x was synthesized by ethylene glycol–citrat... more A novel visible– light driven photocatalyst, BIMNVOX.x was synthesized by ethylene glycol–citrate sol–gel route and microwave- assisted calcination. The phocatalyst was characterized structurally by X–ray powder diffraction (XRPD) and simultaneous thermogravimetric–differential thermal analysis (TG–DTA). Its optical and surface properties were determined by means of UV–vis absorption spectrophotometry and BET– nitrogen adsorption isotherm measurements, respectively. The photocatalytic efficiency of BIMNVOX.x system was investigated by applying the pseudo first- order kinetic model to the photocatalytic degradation reaction of crystal violet, CV dye in aqueous solution under visible light irradiation. The β (orthorhombic) –BIMNVOX phase, space group Acam exhibited the highest photocatalytic degradability, indicating that the photocatalytic efficiency of BIMNVOX catalyst is essentially enhanced by the increased number of catalyst active sites, irrespective of the kind of phase stabilized and the increasing photoabsorption ability with Mn dopant content. Moreover, the possible photocatalytic degradation mechanism of aqueous CV dye solution under visible light irradiation was also proposed.
Allelopathic effects of khat leaves residues (25 and 50 g) and alleviative effects of salicylic a... more Allelopathic effects of khat leaves residues (25 and 50 g) and alleviative effects of salicylic acid (0.5 mM) in wheat roots were carefully investigated in this study. Khat leaves residues stimulated hydrogen peroxide (H2O2), lipid peroxidation, ascorbate (ASA), glutathione (GHS) and non-proteinthiol (NPT) contents. Salicylic acid (SA) was found to inhibit the stimulatory role of khat leaves residues on the production of H2O2 and lipid peroxidation in roots of wheat plants. On the other hand, SA increased ASA, GSH and NPT contents. Catalase (CAT) and ascrobate peroxide (APX) activities were increased significantly in plants growing in soil amended with khat leaves residues, while the activity of peroxidase (POD) was slightly decreased. SA additively inhibited the stimulatory effect of khat leaves residues on CAT and APX activities. In addition, the applied SA increased POD activity. Residues of khat leaves in the soil showed an inhibitory effect on pectin and cellulose fractions of roots. However, hemicellulose content of roots was stimulated. Soaking wheat caryopses in SA counteracted partially or completely the adverse effect of khat leaves residues on pectin and cellulose composition. Furthermore, the data clearly demonstrated the capability of SA treatment in retarding the stimulatory role of khat leaves residues on the production of hemicellulose in roots of wheat plants.
The release of Azo dyes with wastewaters from various industries, factories, and labo... more The release of Azo dyes with wastewaters from various industries, factories, and laboratories, can cause serious environmental problems and a public health concern. A novel BINIVOX.x photocatalyst series with the general formula, ; 0 ≤ x ≤ 0.20 was successfully synthesized by a solid state reaction method and the as-synthesized photocatalyst powder was characterized by X-ray powder diffraction (XRPD), differential thermal analysis (DTA), UV–vis diffuse reflectance spectroscopy (UV–vis/DRS) and BET surface area. The photocatalytic activity of BINIVOX.x photocatalyst series was evaluated by means of the degradation of a new Azo dye, denoted as 4-SPPN in aqueous solution under visible light irradiation. The highest photocatalytic efficiency was reported for the stabilized ʹ– BINIVOX phases (tetragonal, space group I4/m mm ). The reasons for this enhanced photocatalytic activity were revealed, and a possible photocatalytic degradation mechanism of 4–SPPN dye proposed under visible light irradiation was also illustrated. It is interesting to note that the results obtained from this study provide convincing evidences for promising environmental applications of ʹ– BINIVOX phases, particularly in their efficient photocatalysis under visible light irradiation for the treatment of industrial wastewaters polluted by organic dyes.
The electrochemical analysis of ErBa 2 Cu 3 O 7 (ErBCO) superconductor materials, adhered at a gl... more The electrochemical analysis of ErBa 2 Cu 3 O 7 (ErBCO) superconductor materials, adhered at a glassy carbon electrode surface placed in an aqueous media has been investigated by cyclic voltammetry technique. Voltammetric determination of the oxidation of Thiocyanate in 0.1 M NH 4 Cl electrolyte solution by solid phase voltammetry has shown the effect of copper-thiocyanate complexes. Observation revealed a high peak of ErBCO appears at 220 mV vs Ag/AgCl when there is an absence of thiocyanate, while in the presence of thiocyanate, peak current increases by 3.1. The voltammetric response of the ErBCO was found to depend greatly on the scan rate and pH. From CC studies, the amount of charge, Q that was present on the electrode surface is 5.513 µC/cm 2 . The diffusion coefficient,D, value for the copper-thiocyanate complexes was determined to be 7.4810 -05 cm 2 /s .
Electrochemical analyses of Er 1-x Zn x Ba 2 Cu 3 O 7-δ superconductor series were studied using ... more Electrochemical analyses of Er 1-x Zn x Ba 2 Cu 3 O 7-δ superconductor series were studied using solid phase cyclic voltammetry technique. Samples were synthesized via coprecipitation method, and the powder X-ray diffraction (XRD) patterns showed a minor phase of Er 2 BaCuO 5 (211) at higher content of Zn. The higher electrochemical response of current appeared at x=0.2 where the secondary phase was investigated. This phase played a major role in the electrochemical behavior. Cyclic voltammetry of the sample on glassy carbon electrodes in 0.1 M NH 4 Cl at pH 4.12 showed four major peaks attributed to first and second red-ox couple due to the formation of copper complexes. The sensitivity under conditions of cyclic voltammetry is significantly dependant on pH and scan rate. From chronocoulometry (CC) and chronoamperometry (CA) studies, the amount of charge, Q increased from 497.25 μC/cm 2 for the pure sample up to 808.01 μC/cm 2 for doped 0.2 mole of Zn while the diffusion coefficient, D recorded for the pure and 0.2 mole doped samples were 7.4710 -05 and 7.3110 -05 cm 2 /s, respectively.
Journal of Superconductivity and Novel Magnetism, 2012
Zn- and Ca-doped ErBa2Cu3O7−δ were successfully prepared via coprecipitation method using metal a... more Zn- and Ca-doped ErBa2Cu3O7−δ were successfully prepared via coprecipitation method using metal acetates as the starting salts. The precipitated samples were calcined for 20 h at 900 °C and sintered at 920 °C for 24 h. All heat treatments were carried out under oxygen environment. Results show that there is a selectivity of the doping site depending on the ionic radius of the dopant. Furthermore, increase in the critical temperature, T c , was observed in 0.05 mole of calcium and zinc doped samples. The difference in ionic radius of the dopant led to the increase in porosity as the ionic radius decreases. On the other hand, structural distortion increased as the difference of ionic radius became larger.
Thin Solid Films
Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors synthesise... more Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors synthesised via co-precipitation (COP) method were investigated by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis. All samples showed identical thermal decomposition behaviour from the thermogram in which 5 major weight losses were observed. However, XRD of the samples at different heat treatment temperatures showed different diffraction patterns indicating different thermolytic processes. Meanwhile, transmission electron microscopy and surface area analysis revealed that the powders obtained from COP have particle sizes ranging from 7 to 12 nm with relatively large surface area. Molar ratios of prepared samples obtained were near to the theoretical values as confirmed by elemental analyses using X-ray fluorescence (XRF). The TC(R=0) for sintered YGd, YNd and NdGd were 87 K, 86 K and 90 K, respectively. Surface morphological study via scanning electron microscope showed the structures of samples were dense and non porous.
Low-crystalline polypropylene films (PP) were irradiated with different doses of γ-radiation (0, ... more Low-crystalline polypropylene films (PP) were irradiated with different doses of γ-radiation (0, 1, 2.5, 5, 7.5 and 10 Mrad). Differential scanning calorimetry, (DSC), wide-angle X-ray diffraction (WAXD) and FT-IR measurements were used to study the effects of γ-radiation on crystallinity, crystalline structure and thermal changes. It was found that crystalline structure, thermal behavior and crystallinity significantly changed with γ-irradiation. The crystallinity changes mainly depend on γ-irradiation dose, chain scission and crosslinking. The rise in crystallinity was found to be limited and related to chain scission. However, the reduction was accompanied by formation of crosslinking.
A novel visible– light driven photocatalyst, BIMNVOX.x was synthesized by ethylene glycol–citrat... more A novel visible– light driven photocatalyst, BIMNVOX.x was synthesized by ethylene glycol–citrate sol–gel route and microwave- assisted calcination. The phocatalyst was characterized structurally by X–ray powder diffraction (XRPD) and simultaneous thermogravimetric–differential thermal analysis (TG–DTA). Its optical and surface properties were determined by means of UV–vis absorption spectrophotometry and BET– nitrogen adsorption isotherm measurements, respectively. The photocatalytic efficiency of BIMNVOX.x system was investigated by applying the pseudo first- order kinetic model to the photocatalytic degradation reaction of crystal violet, CV dye in aqueous solution under visible light irradiation. The β (orthorhombic) –BIMNVOX phase, space group Acam exhibited the highest photocatalytic degradability, indicating that the photocatalytic efficiency of BIMNVOX catalyst is essentially enhanced by the increased number of catalyst active sites, irrespective of the kind of phase stabilized and the increasing photoabsorption ability with Mn dopant content. Moreover, the possible photocatalytic degradation mechanism of aqueous CV dye solution under visible light irradiation was also proposed.
Allelopathic effects of khat leaves residues (25 and 50 g) and alleviative effects of salicylic a... more Allelopathic effects of khat leaves residues (25 and 50 g) and alleviative effects of salicylic acid (0.5 mM) in wheat roots were carefully investigated in this study. Khat leaves residues stimulated hydrogen peroxide (H2O2), lipid peroxidation, ascorbate (ASA), glutathione (GHS) and non-proteinthiol (NPT) contents. Salicylic acid (SA) was found to inhibit the stimulatory role of khat leaves residues on the production of H2O2 and lipid peroxidation in roots of wheat plants. On the other hand, SA increased ASA, GSH and NPT contents. Catalase (CAT) and ascrobate peroxide (APX) activities were increased significantly in plants growing in soil amended with khat leaves residues, while the activity of peroxidase (POD) was slightly decreased. SA additively inhibited the stimulatory effect of khat leaves residues on CAT and APX activities. In addition, the applied SA increased POD activity. Residues of khat leaves in the soil showed an inhibitory effect on pectin and cellulose fractions of roots. However, hemicellulose content of roots was stimulated. Soaking wheat caryopses in SA counteracted partially or completely the adverse effect of khat leaves residues on pectin and cellulose composition. Furthermore, the data clearly demonstrated the capability of SA treatment in retarding the stimulatory role of khat leaves residues on the production of hemicellulose in roots of wheat plants.
The release of Azo dyes with wastewaters from various industries, factories, and labo... more The release of Azo dyes with wastewaters from various industries, factories, and laboratories, can cause serious environmental problems and a public health concern. A novel BINIVOX.x photocatalyst series with the general formula, ; 0 ≤ x ≤ 0.20 was successfully synthesized by a solid state reaction method and the as-synthesized photocatalyst powder was characterized by X-ray powder diffraction (XRPD), differential thermal analysis (DTA), UV–vis diffuse reflectance spectroscopy (UV–vis/DRS) and BET surface area. The photocatalytic activity of BINIVOX.x photocatalyst series was evaluated by means of the degradation of a new Azo dye, denoted as 4-SPPN in aqueous solution under visible light irradiation. The highest photocatalytic efficiency was reported for the stabilized ʹ– BINIVOX phases (tetragonal, space group I4/m mm ). The reasons for this enhanced photocatalytic activity were revealed, and a possible photocatalytic degradation mechanism of 4–SPPN dye proposed under visible light irradiation was also illustrated. It is interesting to note that the results obtained from this study provide convincing evidences for promising environmental applications of ʹ– BINIVOX phases, particularly in their efficient photocatalysis under visible light irradiation for the treatment of industrial wastewaters polluted by organic dyes.
The electrochemical analysis of ErBa 2 Cu 3 O 7 (ErBCO) superconductor materials, adhered at a gl... more The electrochemical analysis of ErBa 2 Cu 3 O 7 (ErBCO) superconductor materials, adhered at a glassy carbon electrode surface placed in an aqueous media has been investigated by cyclic voltammetry technique. Voltammetric determination of the oxidation of Thiocyanate in 0.1 M NH 4 Cl electrolyte solution by solid phase voltammetry has shown the effect of copper-thiocyanate complexes. Observation revealed a high peak of ErBCO appears at 220 mV vs Ag/AgCl when there is an absence of thiocyanate, while in the presence of thiocyanate, peak current increases by 3.1. The voltammetric response of the ErBCO was found to depend greatly on the scan rate and pH. From CC studies, the amount of charge, Q that was present on the electrode surface is 5.513 µC/cm 2 . The diffusion coefficient,D, value for the copper-thiocyanate complexes was determined to be 7.4810 -05 cm 2 /s .
Electrochemical analyses of Er 1-x Zn x Ba 2 Cu 3 O 7-δ superconductor series were studied using ... more Electrochemical analyses of Er 1-x Zn x Ba 2 Cu 3 O 7-δ superconductor series were studied using solid phase cyclic voltammetry technique. Samples were synthesized via coprecipitation method, and the powder X-ray diffraction (XRD) patterns showed a minor phase of Er 2 BaCuO 5 (211) at higher content of Zn. The higher electrochemical response of current appeared at x=0.2 where the secondary phase was investigated. This phase played a major role in the electrochemical behavior. Cyclic voltammetry of the sample on glassy carbon electrodes in 0.1 M NH 4 Cl at pH 4.12 showed four major peaks attributed to first and second red-ox couple due to the formation of copper complexes. The sensitivity under conditions of cyclic voltammetry is significantly dependant on pH and scan rate. From chronocoulometry (CC) and chronoamperometry (CA) studies, the amount of charge, Q increased from 497.25 μC/cm 2 for the pure sample up to 808.01 μC/cm 2 for doped 0.2 mole of Zn while the diffusion coefficient, D recorded for the pure and 0.2 mole doped samples were 7.4710 -05 and 7.3110 -05 cm 2 /s, respectively.
Journal of Superconductivity and Novel Magnetism, 2012
Zn- and Ca-doped ErBa2Cu3O7−δ were successfully prepared via coprecipitation method using metal a... more Zn- and Ca-doped ErBa2Cu3O7−δ were successfully prepared via coprecipitation method using metal acetates as the starting salts. The precipitated samples were calcined for 20 h at 900 °C and sintered at 920 °C for 24 h. All heat treatments were carried out under oxygen environment. Results show that there is a selectivity of the doping site depending on the ionic radius of the dopant. Furthermore, increase in the critical temperature, T c , was observed in 0.05 mole of calcium and zinc doped samples. The difference in ionic radius of the dopant led to the increase in porosity as the ionic radius decreases. On the other hand, structural distortion increased as the difference of ionic radius became larger.
Thin Solid Films
Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors synthesise... more Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors synthesised via co-precipitation (COP) method were investigated by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis. All samples showed identical thermal decomposition behaviour from the thermogram in which 5 major weight losses were observed. However, XRD of the samples at different heat treatment temperatures showed different diffraction patterns indicating different thermolytic processes. Meanwhile, transmission electron microscopy and surface area analysis revealed that the powders obtained from COP have particle sizes ranging from 7 to 12 nm with relatively large surface area. Molar ratios of prepared samples obtained were near to the theoretical values as confirmed by elemental analyses using X-ray fluorescence (XRF). The TC(R=0) for sintered YGd, YNd and NdGd were 87 K, 86 K and 90 K, respectively. Surface morphological study via scanning electron microscope showed the structures of samples were dense and non porous.