Calorimetric studies of the crystallization process in a-Se75S25-xAgx chalcogenide glasses

Shamshad A. Khan,F.S. Al-Hazmi,A.S. Faidah,A.A. Al-Ghamdi 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Calorimetric studies of amorphous Se75S25-xAgx (x = 2, 4, 6 and 8) chalcogenide glasses are made at different heating rates (5, 10, 15 and 20 K/min) under non-isothermal condition using Differential scanning calorimetry. The values of glass transition temperature and crystallization temperature are observed to be composition and heating rate dependence. From the heating rate dependence of glass transition temperature and crystallization temperature, the activation energy for structural relaxation (△Et), the activation energy of crystallization (△Ec) and the order parameter (n) have been calculated. It is observed that Se75S19Ag6 has a minimum value of activation energy for structural relaxation (△Et), which indicates that this particular glass has a larger probability to jump to a state of lower configurational energy and higher stability in the glassy region. On the basis of the obtained experimental data the temperature difference (Tc - Tg) is found to be maximum for Se75S19Ag6, which further indicate that this glass is the thermally most stable in the entire composition range of investigation. Calorimetric studies of amorphous Se75S25-xAgx (x = 2, 4, 6 and 8) chalcogenide glasses are made at different heating rates (5, 10, 15 and 20 K/min) under non-isothermal condition using Differential scanning calorimetry. The values of glass transition temperature and crystallization temperature are observed to be composition and heating rate dependence. From the heating rate dependence of glass transition temperature and crystallization temperature, the activation energy for structural relaxation (△Et), the activation energy of crystallization (△Ec) and the order parameter (n) have been calculated. It is observed that Se75S19Ag6 has a minimum value of activation energy for structural relaxation (△Et), which indicates that this particular glass has a larger probability to jump to a state of lower configurational energy and higher stability in the glassy region. On the basis of the obtained experimental data the temperature difference (Tc - Tg) is found to be maximum for Se75S19Ag6, which further indicate that this glass is the thermally most stable in the entire composition range of investigation.

A Protective Mechanism in Lungs of Rats Experimentally Infected with Aspergillus fumigatus

Yehia A G. Mahmoud,Abdulaziz Yahya Al Ghamdi,Eman H. F. Abd El Zaher The Korean Society of Mycology 2011 Mycobiology Vol.39 No.1

Aspergillus fumigatus is associated with invasive disease aspergillosis in immunocompromised individuals. The major aim of this study was to investigate the biochemical and immunological responses of male Wistar rats against A. fumigatus experimentally-induced pulmonary fungal infection. Nostril experimental exposure of male Wistar rats to a high dose of A. fumigatus freeze-dried preparation for only 24 hr resulted in a significant increase in levels of catalase, nitric oxide and lipid peroxide in lung homogenates, compared to those of the control animals. However, the oxidative status of the lungs of rats challenged with killed fungus did not change significantly, except for the stimulation in the level of lipid peroxide. IgG level was significantly elevated only in rats that received two low doses of fungus, compared to unexposed animals (p < 0.005). Examining the lung of rats exposed to A. fumigatus revealed no abnormal changes, except for pus in bronchial lumen spaces and per bronchial inflammation. Histologically, large numbers of granuloma cells were evident in the lungs of challenged rats, while no granuloma formation was evident in the lungs of rats exposed to killed fungus.

A novel barium oxide-based Iraqi sand glass to attenuate the low gamma-ray energies: Fabrication, mechanical, and radiation protection capacity evaluation

Al-Saeedi F.H.F.,Sayyed M.I.,Kapustin F.L.,Al-Ghamdi Hanan,Kolobkova E.V.,Tashlykov O.L.,Almuqrin Aljawhara H.,Mahmoud K.A. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

In the present work, untreated Iraqi sand with grain sizes varied between 100 and 200 mm was used to produce a colored glass sample that has shielding features against the low gamma-ray energy. Therefore, a weight of 70e60 wt % sand was mixed with 9e14 wt% B2O3, 8e10 wt% Na2O, 4e6 wt% of CaO, 3e6 wt% Al2O3, in addition to 0.3% of Co2O3. After melting and annealing the glass sample, the X-ray diffraction spectrometry was applied to affirm the amorphous phase of the fabricated glass samples. Moreover, the X-ray dispersive energy spectrometry was used to measure the chemical composition, and the MH-300A densimeter was applied to measure the fabricated sample's density. The Makishima-Makinzie model was applied to predict the mechanical properties of the fabricated glass. Besides, the Monte Carlo simulation was used to estimate the fabricated glass sample's radiation shielding capacity in the low-energy region between 22.1 and 160.6 keV. Therefore, the simulated linear attenuation coefficient changed between 10.725 and 0.484 cm1 , raising the gamma-ray energy between 22.1 and 160.6 keV. Also, other shielding parameters such as a half-value layer, pure lead equivalent thickness, and buildup factors were calculated

Chrysanthemum extract and extract prepared silver nanoparticles as biocides to control Aedes aegypti (L.), the vector of dengue fever

Hamed A. Ghramh,Kh.M. Al-Ghamdi,Jazem A. Mahyoub,Essam H. Ibrahim 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Mosquitoes play a key role in the transmission of some important diseases. The need for controlling these insectsis critical to reduce their risks to human and domesticated animals. Recently the trend to explore effectivechemical compounds from local plants has begun as a safe means of control. The present study aimed to evaluatethe anti-larval activity of Chrysanthemum extract and the prepared silver nanoparticle (AgNPs) against the Aedesaegypti mosquito, the dengue vector in Saudi Arabia. A series of different concentrations of ethanol extract andextract prepared AgNPs against the fourth-life larvae was tested. The effective concentrations of crude extractand AgNPs ranged from 50 to 250 and 10 to 30 ppm respectively, and the death percentages corresponding tothese concentrations ranged from 18 to 92 and 36 to 96% respectively. According to the LC50 values of treatedlarvae, AgNPs (12.754 ppm) is more effective against A. aegypti mosquito larvae than the crude extract(228.345 ppm) at about 17.9 times. The mixing of the plant extract with the silver nitrate has led to potentiation. This is due to the synergy that occurs between the extract and the silver particles during the reduction process. The compounds in the extract are related to the surface of the particles, increasing the strength of their effects. Itis recommend to separate the active elements in the Chrysanthemum plant and its preparation in the form ofnanoparticles as a promising compound in mosquito control programs with least damage to human kind and theenvironment.

Synthesis and characterization of novel Cu2O/PVDF nanocomposites for flexible ferroelectric organic electronic memory devices

Farag S. Al-Hazmi,Dago M. de Leeuw,A.A. Al-Ghamdi,F.S. Shokr 한국물리학회 2017 Current Applied Physics Vol.17 No.9

Copper oxide nanoparticles loaded Poly(vinylidene fluoride) (PVDF) nanocomposites, at concentrations from 1 to 9 wt%, were developed by casting technique. The effect of the Cu2O nanoparticles on the structure, thermal, mechanical and dielectric properties of the PVDF were inspected. The scanning electron microscopy (FE-SEM) revealed the well dispersion of the Cu2O nanoparticles into the PVDF matrix up to 5 wt%. The X-ray diffraction (XRD) patterns and the infrared spectroscopy (FTIR) measurements implied that the inclusion of the Cu2O nanoparticles into the PVDF matrix leads to a transform of the non-polar semi-crystalline a-phase of the neat PVDF to highly crystallized polar b-phase. Moreover, an increase of the thermal stability and crystallinity of the PVDF after the incorporation of the Cu2O nanoparticles was achieved. The Cu2O/PVDF nanocomposites exhibited excellent cyclic mechanical property compared to the neat PVDF. The introduction of 5 wt% Cu2O nanoparticles into the PVDF composites resulted in remarkable increase of the dielectric constant by 13 times while the dielectric loss was very low. A device based on Al/5 wt% Cu2O doped PVDF/Pt structure is developed. This device shows ferroelectric hysteresis with butterfly like shape and exhibited remanent polarization of 11.2 mC/cm2 with coercive field of 49 MV/m. These superior properties enable the developed Cu2O/PVDF nanocomposite films to be a potential candidate in the field of ferroelectric organic electronic memory devices.

Phytochemical composition, protective and therapeutic effect on gastric ulcer and a-amylase inhibitory activity of Achillea biebersteinii Afan.

Howaida I. Abd-Alla,Nagwa M. M. Shalaby,Manal A. Hamed,Nagy Saba El-Rigal,Samira N. Al-Ghamdi,Jalloul Bouajila 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.1

Three sesquiterpene lactones [two germacranolides (micranthin and sintenin) and one guaianolide (4b,10adihydroxy- 5b,7b,8bH-guaia-1,11(13)dien-12,8a-olide)] and four derivatives of 3-methoxy flavones (santin, quercetagetin- 3,6,30-trimethyl ether, quercetagetin-3,6-dimethyl ether, and 5,7 dihydroxy 3,30,40-trimethoxy flavone) were isolated from the ethyl acetate extract (EAE) of the aerial parts of Achillea biebersteinii Afan. (Asteraceae). Evaluation of protective and therapeutic effects of EAE against ethanol-induced gastric ulcer in rats was carried. Antiulcer activity evaluation was done through measuring ulcer indices, stomach acidity, gastric volume and lesion counts. Oxidative stress markers; malondialdehyde, glutathione and superoxide dismutase were also estimated. The work was extended to determine the histopathological assessment of the stomach. Gastric ulcer exhibited a significant elevation of the ulcer index and oxidative stress markers. The extract attenuated these increments and recorded protective and therapeutic effects against gastric ulcer. Hyperglycaemia increases the mucosal susceptibility to ulcerogenic stimuli and predisposes gastric ulceration. In vitro a-amylase inhibitory assay was applied to evaluate the post prandial antihyperglycaemia activity. The result showing that the EAE has the ability to reduce starch-induced postprandial glycaemic excursions by virtue of potent intestinal a-amylase inhibitory activity. These findings demonstrated the remarkable potential of A. biebersteinii as valuable source of antiulcer agent with post prandial hyperglycaemia lowering effect.

Annealing and laser irradiation effects on optical constants of Ga_15Se_85 and Ga_15Se_83In_2 chalcogenide thin films

A.A. Al-Ghamdi,Shamshad A. Khan,S. Al-Heniti,F.A. Al-Agel,M. Zulfequar 한국물리학회 2011 Current Applied Physics Vol.11 No.3

Chalcogenide thin films finds extensive applications in optical imaging, optical recording, integrated optics, optical communications and microelectronics. Optical constants (absorption coefficient, refractive index and extinction coefficient) of amorphous, thermally annealed and laser irradiated Ga_15Se_85 and Ga_15Se_83In_2 thin films deposited by thermal evaporation onto chemically cleaned glass substrate, were calculated from absorbance and reflectance spectra as a function of photon energy in the wavelength region 400―900 nm. Analysis of the optical absorption data shows that the rule of non-direct transitions predominates. It has been found that the absorption coefficient increasing with increasing the exposure time of laser irradiation and also by increasing photon energy. The optical band gap decreases with increasing annealing temperatures. The refractive index (n) decreases, while the extinction coefficient (k)increases with increasing annealing temperature. The laser irradiated thin films showed a decrease in optical band gap and absorption coefficient with increasing exposure time of laser irradiation. The values of refractive index (n) increases and extinction coefficient (k) decreases with increasing exposure time of laser irradiation. The results have been analyzed on the bases of thermal annealing and laser irradiation effects in the chalcogenide thin films.

Synthesis, Characterization and Electrical Properties of Hydroxyapatite Nanoparticles from Utilization of Biowaste Eggshells

Nadia Abdel Aal,M. Bououdina,A. Hajry,A. A. Chaudhry,J. A. Darr,A. A. Al-Ghamdi,E. H. El-Mossalamy,Attieh A. Al-Ghamdi,YongKielSung,Farid El-Tantawy 한국생체재료학회 2011 생체재료학회지 Vol.15 No.2

Hydroxyapatite(HAP) nanoparticles were successfully prepared from the biowaste chicken eggshells and phosphoric acid solution by chemical precipitation methods. The structures of HAP were characterized in terms of the X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform-infrared (FT-IR) spectroscopy. The effect of temperature on the crystallinity and lattice parameters of prepared HAP was monitored by X-ray powder diffraction. Energy dispersive X-ray analysis revealed that the HAP had a Ca/P molar ratio of about 1.65 and 1.69for as prepared and sintered HAP at 1200oC (1 hour), respectively. The temperature dependence on the electrical conductivity of sintered HAP nanoparticle was investigated. Furthermore, dielectric properties such as dielectric constant and dielectric loss as a function of frequency for the sintered HAP were also studied.

Parameter-formability Relationship in ISF of Tri-Layered Cu-Steel-Cu Composite Sheet Metal: Response Surface and Microscopic Analyses

Khalid A Al-Ghamdi,Ghulam Hussain 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.12

This study analyzes the parameters effects on the formability in Incremental-Sheet-Forming (ISF) of a tri-layered Cu-Steel-Cu composite sheet. The effects are found to be very complex, highly interactive, and somehow different from those reported in the literature for the monolithic sheet metals. High rotational speed and feed rate pose positive effect, regardless of tool size and step size, when the composite sheet is annealed to low temperature (e.g., 400oC). These high settings have adverse effects, contrarily, specifically when the tool diameter is large and the sheet is annealed to high temperature (e.g., 700oC). This, as per microscopic observation, is attributed to delamination of high-annealed laminates (characterized by low bond strength). The delamination as dictated by hole drill tests possibly occurs due to a reason that the laminates experience low compressive residual stress when processed with the aforesaid parameters. The XRD analysis reveals that the formation of any new element does not occur during ISF, thus ruling out the potential effect of material processing on microstructural change on the sheet fracture. Finally, a correlation is formulated using which one without doing experiments can choose the optimum parameters for the ISF of composite sheet with objective to maximize the formability.

Effect of cadmium addition on the optical constants of thermally evaporated amorphous Se.S.Cd thin films

Shamshad A. Khan,F.S. Al-Hazmi,S. Al-Heniti,A.S. Faidah,A.A. Al-Ghamdi 한국물리학회 2010 Current Applied Physics Vol.10 No.1

Se75S25-xCdx is a promising ternary material, which has received considerable attention due to its applications in the fabrication of various solid state devices. These have distinct advantages, large packing density,mass replication, fast data rate, high signal-to-noise ratio and high immunity to defects. Measurements of optical constants (absorption coefficient, refractive index, extinction coefficient, real and imaginary part of the dielectric constant) have been made on Se75S25-xCdx (where x = 0, 2, 4, 6 and 8) thin films of thickness 3000 Å as a function of photon energy in the wave length range 400–1000 nm. It has been found that the optical band gap and extinction coefficient increases while the value refractive index decreases on incorporation of cadmium in Se–S system. The results are interpreted in terms of the change in concentration of localized states due to the shift in Fermi level. Due to the large absorption coefficient and compositional dependence of reflectance, these materials may be suitable for optical disk material.