N. Salah - Academia.edu (original) (raw)

Papers by N. Salah

Research paper thumbnail of Holographie numérique appliquée aux écoulements, granulométrie et vélocimétrie

Research paper thumbnail of Direct Bandgap Material Based on Thin Film of Te97Ga3 Nanoparticles

ECS Journal of Solid State Science and Technology, 2012

ABSTRACT

Research paper thumbnail of The performance of Silver modified Tungsten Oxide for the removal of 2-CP and 2-NP in sunlight exposure: Optical, electrochemical and photocatalytic properties

Arabian Journal of Chemistry, 2015

ABSTRACT The optical and electrochemical characterization of synthesized Ag+ modified WO3 photoca... more ABSTRACT The optical and electrochemical characterization of synthesized Ag+ modified WO3 photocatalysts was performed and its photocatalytic activity was estimated in the visible region (420-800 nm) of sunlight for the degradation of 2-chloro and 2-nitrophenol. The catalysts with the varying loading of Ag+ ranging from 0.5% to 10%, exhibited significantly higher activity as compared to pure WO3. Attempts were made to correlate the enhanced activity of Ag+ loaded catalysts with the optical and electrochemical properties. At lower loading (up to 1% Ag+), the enhanced degradation was attributed to the excited electron trap and transfer ability of surface mounted Ag+ species, while the synergic effect between the WO3 support and surface Ag2O resulted the same at higher loadings. The electrochemical properties of the synthesized powders, in comparison to pure WO3, also supported the same findings. The identification of intermediates and estimation of the released anions evidenced the contribution of both hydroxyl radicals (HO•) and superoxide anion (O2•-) radicals in the degradation process. The identification of aliphatic oxygenates as majority intermediates and release of respective ions verified the replacement of Cl- and NO2 groups, insertion of oxygen and aromatic ring cleavage.

Research paper thumbnail of Infuenzae A (H1N1) : about 189 cases

La Tunisie médicale, 2014

Influenza A (H1N1) is a contagious acute respiratory infection caused by a subtype influenza viru... more Influenza A (H1N1) is a contagious acute respiratory infection caused by a subtype influenza virus A (H1N1). The later had caused a pandemic in 2009. Despite its low mortality, the disease was more severe in some subgroups. Describe confirmed cases of influenza A (H1N1) addressed to the pulmonary department of the Rabta hospital and identify risk factors. During the pandemic influenza A (H1N1), pulmonary department of Rabta hospital was identified among the centers to receive and detect new cases in addition to hospitalization of severe ones. All subjects had nasal and pharyngeal swabs. The authors distinguished non-severe and severe cases; hospitalization was indicated for severe forms. From September 2009 to March 2010, influenza A (H1N1) has been confirmed in 189 patients. The average age was 27.3 years [2-72 years]. Sex ratio was 1.2. Contagion was found in all patients. Twenty-two patients were hospitalized for the severe form. Mean age was 56 years, sex ratio was 0.47. Among t...

Research paper thumbnail of Manifestations neuropsychiatriques secondaires au traitement par cycloserine au cours de la tuberculose multirésistante

Revue des Maladies Respiratoires, 2006

Research paper thumbnail of Amelioration of radiation-induced oxidative stress and biochemical alteration by SOD model compounds in pre-treated γ-irradiated rats

Introduction: The role of metalloelements in tissue maintenance, function and response to injury ... more Introduction: The role of metalloelements in tissue maintenance, function and response to injury offer a new approach to decreasing and/or treating radiation injury. We investigated the roles of CuL 2 SO 4 , [MnL 2 O] 2 Cl 4 (H 2 O) 2 and [(VL 2 O)(VL 2 H 2 O)]Cl 6 complexes (L=2-methylaminopyridine) of SOD-mimetic activities, in ameliorating the radiation-induced oxidative stress and alterations in some biochemical parameters in liver, kidney, spleen and brain in pretreated female rats exposed to girradiation. Methods: Both untreated-rats and rats treated with the above complexes were subjected to whole-body g-irradiation (6 Gy). 5V-Nucleotidase (5V-NT), acetylcholinesterase (AChE), adenosne triphosphatase (ATPase), superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GSSG-R) were assessed as well as liver DNA and RNA contents and total protein concentration were estimated in tissue homogenates of the above organs. The same parameters were assessed in non-irradiated treated rats and normal control rats. Results were compared to irradiated non-treated and normal control rats. Results: Pretreatment of g-irradiated rats with Mn(IV) or V(IV) complex produced a significant decrease in liver 5V-NT activity compared to the corresponding value of the untreated irradiated rats. In contrast, liver DNA and RNA contents and brain AChE and ATPase activities were significantly increased in irradiated rat group pre-treated with these metal complexes. Cu II, Mn IV or V IV complex inoculation prior to irradiation of normal rats exhibited a significant increase in SOD, CAT, GSSG-R activities and protein content of liver, kidney, spleen and brain homogenates compared with that of the untreated irradiated rats. The treatment of non-irradiated rats with these complexes produced a highly significant increase in mean activities of SOD and CAT, with no changes in other parameters vs. controls. Conclusions: Cu(II), Mn(IV) and V(IV) 2-methylaminopyridine complexes offer a physiological approach to ameliorate the radiation-induced biochemical alterations. In addition, they provide sufficient protection against radiation injury of radiosensitive tissues. D

Research paper thumbnail of Luminescence Properties of CaF

Research paper thumbnail of TL response of LiF: Mg, Cu, P to 24 Me V of 7 Li 2+ ions

Research paper thumbnail of Carbon Ions Irradiation on CaSO4: Dy Nanocubes

Research paper thumbnail of OPTICAL AND ELECTRICAL CHARACTERIZATION OF ZnO THIN FILM

International Journal of Nanoscience, 2010

Title: Optical and Electrical Characterization of ZnO Thin Film. Authors: Khan, Zishan H.; Islamu... more Title: Optical and Electrical Characterization of ZnO Thin Film. Authors: Khan, Zishan H.; Islamuddin; Kumar, Ravi K.; Salah, Numan; Habib, Sami; El-Hamidy, SM Abdallah; Rafat, M.; Husain, M. Publication: International Journal of Nanoscience, vol. 09, issue 05, p. 423. ...

Research paper thumbnail of Nanoparticles of Al2O3:Cr as a sensitive thermoluminescent material for high exposures of gamma rays irradiations

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

Aluminum Oxide (Al 2 O 3 ) doped with proper activators is a highly sensitive phosphor commonly u... more Aluminum Oxide (Al 2 O 3 ) doped with proper activators is a highly sensitive phosphor commonly used for radiation dosimetry using thermoluminescence (TL) technique. Nanoparticles of this material activated with Chromium (Cr) have been synthesized using the propellant chemical combustion technique and studied for their TL response. They were characterized by X-ray diffraction and scanning electron microscope. The synthesized material has spherical nanoparticles with grain size around 25 nm. These nanoparticles were exposed to heavy doses from c-rays of 137 Cs. The TL glow curves show a prominent peak at around 474 K. This peak is found to be sensitive for high exposures of c-rays and has linear response in the range of 100 Gy-20 kGy without showing saturation. This remarkable result suggests that Al 2 O 3 :Cr nanoparticles might be used for the dosimetry of food and seed irradiations.

Research paper thumbnail of Ag/ZnO nanoparticles thin films as visible light photocatalysts

RSC Adv., 2014

Silver (Ag) and zinc oxide (ZnO) nanoparticles were simultaneously deposited on a glass substrate... more Silver (Ag) and zinc oxide (ZnO) nanoparticles were simultaneously deposited on a glass substrate using the radio frequency (RF) sputtering technique at different substrate temperatures. Detailed characterization of the co-sputtered Ag/ZnO thin films was performed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). The as synthesized thin films were tested using UV-Vis diffuse reflectance spectroscopy to evaluate their optical properties. The obtained SEM results show a uniform dispersion of Ag nanoparticles within the ZnO matrix. These nanoparticles have average particle size of 20 nm. The optical band gap value was calculated from UV transmission spectra of Ag/ZnO thin films deposited at various substrate temperatures. This value was observed to be in the visible light range (i.e., 2.7-3.1 eV), which is much smaller than that of pure ZnO (3.37 eV). The photocatalytic activity of the produced thin films was evaluated through visible light photodegradation of 2-chlorophenol (2-CP) which has been used as a pollutant model in water. The synthesized thin films showed enhanced visible light photocatalytic efficiency towards 2-CP degradation at elevated substrate temperature and retained their catalytic efficiency with only 8% loss in efficiency after four reuse cycles. Kinetic parameters involved in the degradation process were investigated by applying a pseudo-second-order kinetic model.

Research paper thumbnail of Electrical Transport Properties of Ni 95 Ti 5 Catalyzed Multi wall Carbon Nanotubes Film

Journal of Nanomaterials, 2009

ABSTRACT

Research paper thumbnail of Luminescence Properties of CaF 2 Nanostructure Activated by Different Elements

Journal of Nanomaterials, 2015

ABSTRACT Nanostructures of calcium fluoride (CaF2) doped with Eu, Tb, Dy, Cu, and Ag were synthes... more ABSTRACT Nanostructures of calcium fluoride (CaF2) doped with Eu, Tb, Dy, Cu, and Ag were synthesized by the coprecipitation method and studied for their thermoluminescence (TL) and photoluminescence (PL) properties. The PL emission spectrum of pure CaF2 nanostructure has a broad band in the 370-550 nm range. Similar spectra were observed in case of doped samples, beside extra bands related to these impurities. The maximum PL intensity was observed in Eu doped sample. The TL results of Eu, Cu, Ag, and Tb doped samples show weak glow peaks below 125°C, whereas Dy doped one is found to be highly sensitive with a prominent peak at 165°C. This sample was further exposed to a wide range of gamma rays exposures from 137Cs source. The response curve is linear in the 100 Gy-10 kGy range. It is also observed that the particle size of CaF2 nanostructure was significantly reduced by increasing Dy concentration. These results showed that Dy is a proper activator in the host of CaF2 nanostructure, providing a highly sensitive dosimeter in a wide range of exposures and also plays a role as a controlling agent for particle size growth.

Research paper thumbnail of Thermoluminescence of gamma rays irradiated LiF nanocubes doped with different elements

Journal of Luminescence, 2015

ABSTRACT Lithium fluoride (LiF) doped with proper activator is a highly sensitive phosphor, widel... more ABSTRACT Lithium fluoride (LiF) doped with proper activator is a highly sensitive phosphor, widely used as a dosimeter for ionizing radiations. This work reports on the thermoluminesence (TL) response of LiF nanocubes doped with different impurities. These nanocubes were synthesized by the co-precipitation method and characterized by different techniques. The dopants used in this study are Eu, Tb, Dy, Cu and Ag. The gamma radiation induced TL glow peaks are located in the temperature range 120–125 °C. These samples have different TL sensitivities, where Eu doped one is found to be the most TL sensitive. Further irradiations in the dose range from 10 Gy to 30 kGy were performed to LiF:Eu and the obtained result is explained using a proposed multilevel TL model. According to this model, Eu dopant (in Eu3+ ionic form) could induce shallow and deep electron traps in the host of LiF nanocubes. These traps differ in their response according to the doses. The optimum concentration of Eu ions in LiF host is found to be 0.2 mol%. It is also found that LiF nanocubes are thermally stable in the range of 30–400 °C with a single phase. This property along with the good sensitivity of Eu doped one makes this tissue equivalent nanomaterial a proper candidate for heavy dose measurement like swift heavy ions used in radiotherapy.

Research paper thumbnail of Evaluation of sunlight induced structural changes and their effect on the photocatalytic activity of V2O5 for the degradation of phenols

Journal of Hazardous Materials, 2015

Despite knowing the fact that vanadium pentoxide is slightly soluble in aqueous medium, its photo... more Despite knowing the fact that vanadium pentoxide is slightly soluble in aqueous medium, its photocatalytic activity was evaluated for the degradation of phenol and its derivatives (2-hydroxyphenol, 2-chlorophenol, 2-aminophenol and 2-nitrophenol) in natural sunlight exposure. The prime objective of the study was to differentiate between the homogeneous and heterogeneous photocatalysis incurred by dissolved and undissolved V2O5 in natural sunlight exposure. V2O5 was synthesized by chemical precipitation procedure using Triton X-100 as morphology mediator and characterized by DRS, PLS, Raman, FESEM and XRD. A lower solubility of ∼5% per 100ml of water at 23°C was observed after calcination at 600°C. The study revealed no contribution of the dissolved V2O5 in the photocatalytic process. In sunlight exposure, V2O5 powder exhibited substantial activity for the degradation, however, a low mineralization of phenolic substrates was observed. The initial low activity of V2O5 followed by a sharp increase both in degradation and mineralization in complete spectrum sunlight exposure, was further investigated that revealed the decrease in the bandgap and the reduction in the particle size with the interaction of UV photons (<420nm) as this effect was not observable in the exposure of visible region of sunlight. The role of the chemically different substituents attached to an aromatic ring at 2-positions and the secondary interaction of released ions during the degradation process with the reactive oxygen species (ROS) was also explored.

Research paper thumbnail of Sunlight induced formation of surface Bi2O4−x–Bi2O3 nanocomposite during the photocatalytic mineralization of 2-chloro and 2-nitrophenol

Applied Catalysis B: Environmental, 2015

The photocatalytic mineralization of 2-chlorophenol (2-CP) and 2-nitrophenol (2-NP) was investiga... more The photocatalytic mineralization of 2-chlorophenol (2-CP) and 2-nitrophenol (2-NP) was investigated using ␣-Bi 2 O 3 . The experiments were performed both in complete spectrum and in the visible region (420-800 nm) of the sunlight. The materials were fully characterized by means of UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM). ␣-Bi 2 O 3 showed considerably higher activity for the mineralization of 2-nitrophenol and 2chlorophenol under natural sunlight exposure, however still appreciable activity was observed in the visible region. Formation of surface nanocomposites Bi 2 O 4−x -Bi 2 O 3 was observed under sunlight irradiation due to the presence of UV light. The sunlight exposed Bi 2 O 3 , i.e. Bi 2 O 4−x -Bi 2 O 3 composite, showed excellent activity for the degradation and mineralization of 2-CP and 2-NP in the visible region of sunlight. A key role of both hydroxyl and superoxide anion radicals was evidenced in the degradation and mineralization processes under sunlight while only hydroxyl radicals were identified as major facilitators under visible light irradiation.

Research paper thumbnail of Synthesis and Characterization of Se35Te65−𝑥Ge𝑥 Nanoparticle Films and Their Optical Properties

Journal of Nanomaterials, 2012

Thin films of Se 35 Te 65−x Ge x (x = 0, 3, 6, 9, 12) nanoparticles were synthesized using therma... more Thin films of Se 35 Te 65−x Ge x (x = 0, 3, 6, 9, 12) nanoparticles were synthesized using thermal evaporation method. They were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and absorption and transmission spectra. XRD results show that these films are of amorphous nature, while SEM images show nanoparticles with average particle size around 30 nm. No significant changes are observed in morphology of the deposited films by changing concentrations of Te and Ge. The optical behaviors of these films have been studied using the absorption and transmission spectra in the spectral region 400-1100 nm. The absorption, extinction coefficients and refractive index were obtained and investigated in more detail. The optical band gap (E g ) values were also determined and are found to decrease from 0.83 to 0.69 eV by increasing the concentration of Ge from 0 to 12. The transmission spectra for the thin films of Se 35 Te 65−x Ge x nanoparticles show strong absorption at wavelength less than 500 nm and become highly transparent at wavelength above 800 nm. No significant changes in the transmission spectra are observed by increasing concentration of Ge. These results might be useful for development of optical disks and other semiconducting devices based on these nanochalcogenides.

Research paper thumbnail of J-E characteristics of Ni-catalysed multiwalled carbon nanotubes

International Journal of Nano and Biomaterials, 2009

Center of Nanotechnology, King Abdulaziz University, Jeddah, KSA and Department of Applied Scienc... more Center of Nanotechnology, King Abdulaziz University, Jeddah, KSA and Department of Applied Sciences and Humanities, Jamia Millia Islamia (Central University), New Delhi, India E-mail: zishanhk@rediffmail.com *Corresponding author ... Department of Physics, Jamia Millia ...

Research paper thumbnail of Syntheses and characterization of thin films of Te94Se6 nanoparticles for semiconducting and optical devices

Thin Solid Films, 2013

Thin films of Te 94 Se 6 nanoparticles were synthesized using the physical vapor condensation tec... more Thin films of Te 94 Se 6 nanoparticles were synthesized using the physical vapor condensation technique at different argon (Ar) pressures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy, absorption spectrum, photoluminescence (PL) and Raman spectroscopy. XRD results show that the as-grown films have a polycrystalline structure. SEM images display uniform nanoparticles in these films where the size increases from~12 to about 60 nm by decreasing Ar pressure from 667 to 267 Pa. These as-grown thin films were found to have direct band gaps, whose value decreases with increasing particle size. The absorption and extinction coefficients for these films were also investigated. PL emission spectra exhibit three bands peaking at 666, 718 and 760 nm, while Raman spectra displayed three bands located at 123, 143 and 169 cm −1 . No significant changes are observed in positions or intensities of these bands by decreasing the Ar pressure, except that of the last band of PL; where the intensity increases. The obtained results on this Te 94 Se 6 nanomaterial especially its controlled direct bandgap might be useful for development of optical disks and other semiconducting devices.

Research paper thumbnail of Holographie numérique appliquée aux écoulements, granulométrie et vélocimétrie

Research paper thumbnail of Direct Bandgap Material Based on Thin Film of Te97Ga3 Nanoparticles

ECS Journal of Solid State Science and Technology, 2012

ABSTRACT

Research paper thumbnail of The performance of Silver modified Tungsten Oxide for the removal of 2-CP and 2-NP in sunlight exposure: Optical, electrochemical and photocatalytic properties

Arabian Journal of Chemistry, 2015

ABSTRACT The optical and electrochemical characterization of synthesized Ag+ modified WO3 photoca... more ABSTRACT The optical and electrochemical characterization of synthesized Ag+ modified WO3 photocatalysts was performed and its photocatalytic activity was estimated in the visible region (420-800 nm) of sunlight for the degradation of 2-chloro and 2-nitrophenol. The catalysts with the varying loading of Ag+ ranging from 0.5% to 10%, exhibited significantly higher activity as compared to pure WO3. Attempts were made to correlate the enhanced activity of Ag+ loaded catalysts with the optical and electrochemical properties. At lower loading (up to 1% Ag+), the enhanced degradation was attributed to the excited electron trap and transfer ability of surface mounted Ag+ species, while the synergic effect between the WO3 support and surface Ag2O resulted the same at higher loadings. The electrochemical properties of the synthesized powders, in comparison to pure WO3, also supported the same findings. The identification of intermediates and estimation of the released anions evidenced the contribution of both hydroxyl radicals (HO•) and superoxide anion (O2•-) radicals in the degradation process. The identification of aliphatic oxygenates as majority intermediates and release of respective ions verified the replacement of Cl- and NO2 groups, insertion of oxygen and aromatic ring cleavage.

Research paper thumbnail of Infuenzae A (H1N1) : about 189 cases

La Tunisie médicale, 2014

Influenza A (H1N1) is a contagious acute respiratory infection caused by a subtype influenza viru... more Influenza A (H1N1) is a contagious acute respiratory infection caused by a subtype influenza virus A (H1N1). The later had caused a pandemic in 2009. Despite its low mortality, the disease was more severe in some subgroups. Describe confirmed cases of influenza A (H1N1) addressed to the pulmonary department of the Rabta hospital and identify risk factors. During the pandemic influenza A (H1N1), pulmonary department of Rabta hospital was identified among the centers to receive and detect new cases in addition to hospitalization of severe ones. All subjects had nasal and pharyngeal swabs. The authors distinguished non-severe and severe cases; hospitalization was indicated for severe forms. From September 2009 to March 2010, influenza A (H1N1) has been confirmed in 189 patients. The average age was 27.3 years [2-72 years]. Sex ratio was 1.2. Contagion was found in all patients. Twenty-two patients were hospitalized for the severe form. Mean age was 56 years, sex ratio was 0.47. Among t...

Research paper thumbnail of Manifestations neuropsychiatriques secondaires au traitement par cycloserine au cours de la tuberculose multirésistante

Revue des Maladies Respiratoires, 2006

Research paper thumbnail of Amelioration of radiation-induced oxidative stress and biochemical alteration by SOD model compounds in pre-treated γ-irradiated rats

Introduction: The role of metalloelements in tissue maintenance, function and response to injury ... more Introduction: The role of metalloelements in tissue maintenance, function and response to injury offer a new approach to decreasing and/or treating radiation injury. We investigated the roles of CuL 2 SO 4 , [MnL 2 O] 2 Cl 4 (H 2 O) 2 and [(VL 2 O)(VL 2 H 2 O)]Cl 6 complexes (L=2-methylaminopyridine) of SOD-mimetic activities, in ameliorating the radiation-induced oxidative stress and alterations in some biochemical parameters in liver, kidney, spleen and brain in pretreated female rats exposed to girradiation. Methods: Both untreated-rats and rats treated with the above complexes were subjected to whole-body g-irradiation (6 Gy). 5V-Nucleotidase (5V-NT), acetylcholinesterase (AChE), adenosne triphosphatase (ATPase), superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GSSG-R) were assessed as well as liver DNA and RNA contents and total protein concentration were estimated in tissue homogenates of the above organs. The same parameters were assessed in non-irradiated treated rats and normal control rats. Results were compared to irradiated non-treated and normal control rats. Results: Pretreatment of g-irradiated rats with Mn(IV) or V(IV) complex produced a significant decrease in liver 5V-NT activity compared to the corresponding value of the untreated irradiated rats. In contrast, liver DNA and RNA contents and brain AChE and ATPase activities were significantly increased in irradiated rat group pre-treated with these metal complexes. Cu II, Mn IV or V IV complex inoculation prior to irradiation of normal rats exhibited a significant increase in SOD, CAT, GSSG-R activities and protein content of liver, kidney, spleen and brain homogenates compared with that of the untreated irradiated rats. The treatment of non-irradiated rats with these complexes produced a highly significant increase in mean activities of SOD and CAT, with no changes in other parameters vs. controls. Conclusions: Cu(II), Mn(IV) and V(IV) 2-methylaminopyridine complexes offer a physiological approach to ameliorate the radiation-induced biochemical alterations. In addition, they provide sufficient protection against radiation injury of radiosensitive tissues. D

Research paper thumbnail of Luminescence Properties of CaF

Research paper thumbnail of TL response of LiF: Mg, Cu, P to 24 Me V of 7 Li 2+ ions

Research paper thumbnail of Carbon Ions Irradiation on CaSO4: Dy Nanocubes

Research paper thumbnail of OPTICAL AND ELECTRICAL CHARACTERIZATION OF ZnO THIN FILM

International Journal of Nanoscience, 2010

Title: Optical and Electrical Characterization of ZnO Thin Film. Authors: Khan, Zishan H.; Islamu... more Title: Optical and Electrical Characterization of ZnO Thin Film. Authors: Khan, Zishan H.; Islamuddin; Kumar, Ravi K.; Salah, Numan; Habib, Sami; El-Hamidy, SM Abdallah; Rafat, M.; Husain, M. Publication: International Journal of Nanoscience, vol. 09, issue 05, p. 423. ...

Research paper thumbnail of Nanoparticles of Al2O3:Cr as a sensitive thermoluminescent material for high exposures of gamma rays irradiations

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

Aluminum Oxide (Al 2 O 3 ) doped with proper activators is a highly sensitive phosphor commonly u... more Aluminum Oxide (Al 2 O 3 ) doped with proper activators is a highly sensitive phosphor commonly used for radiation dosimetry using thermoluminescence (TL) technique. Nanoparticles of this material activated with Chromium (Cr) have been synthesized using the propellant chemical combustion technique and studied for their TL response. They were characterized by X-ray diffraction and scanning electron microscope. The synthesized material has spherical nanoparticles with grain size around 25 nm. These nanoparticles were exposed to heavy doses from c-rays of 137 Cs. The TL glow curves show a prominent peak at around 474 K. This peak is found to be sensitive for high exposures of c-rays and has linear response in the range of 100 Gy-20 kGy without showing saturation. This remarkable result suggests that Al 2 O 3 :Cr nanoparticles might be used for the dosimetry of food and seed irradiations.

Research paper thumbnail of Ag/ZnO nanoparticles thin films as visible light photocatalysts

RSC Adv., 2014

Silver (Ag) and zinc oxide (ZnO) nanoparticles were simultaneously deposited on a glass substrate... more Silver (Ag) and zinc oxide (ZnO) nanoparticles were simultaneously deposited on a glass substrate using the radio frequency (RF) sputtering technique at different substrate temperatures. Detailed characterization of the co-sputtered Ag/ZnO thin films was performed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). The as synthesized thin films were tested using UV-Vis diffuse reflectance spectroscopy to evaluate their optical properties. The obtained SEM results show a uniform dispersion of Ag nanoparticles within the ZnO matrix. These nanoparticles have average particle size of 20 nm. The optical band gap value was calculated from UV transmission spectra of Ag/ZnO thin films deposited at various substrate temperatures. This value was observed to be in the visible light range (i.e., 2.7-3.1 eV), which is much smaller than that of pure ZnO (3.37 eV). The photocatalytic activity of the produced thin films was evaluated through visible light photodegradation of 2-chlorophenol (2-CP) which has been used as a pollutant model in water. The synthesized thin films showed enhanced visible light photocatalytic efficiency towards 2-CP degradation at elevated substrate temperature and retained their catalytic efficiency with only 8% loss in efficiency after four reuse cycles. Kinetic parameters involved in the degradation process were investigated by applying a pseudo-second-order kinetic model.

Research paper thumbnail of Electrical Transport Properties of Ni 95 Ti 5 Catalyzed Multi wall Carbon Nanotubes Film

Journal of Nanomaterials, 2009

ABSTRACT

Research paper thumbnail of Luminescence Properties of CaF 2 Nanostructure Activated by Different Elements

Journal of Nanomaterials, 2015

ABSTRACT Nanostructures of calcium fluoride (CaF2) doped with Eu, Tb, Dy, Cu, and Ag were synthes... more ABSTRACT Nanostructures of calcium fluoride (CaF2) doped with Eu, Tb, Dy, Cu, and Ag were synthesized by the coprecipitation method and studied for their thermoluminescence (TL) and photoluminescence (PL) properties. The PL emission spectrum of pure CaF2 nanostructure has a broad band in the 370-550 nm range. Similar spectra were observed in case of doped samples, beside extra bands related to these impurities. The maximum PL intensity was observed in Eu doped sample. The TL results of Eu, Cu, Ag, and Tb doped samples show weak glow peaks below 125°C, whereas Dy doped one is found to be highly sensitive with a prominent peak at 165°C. This sample was further exposed to a wide range of gamma rays exposures from 137Cs source. The response curve is linear in the 100 Gy-10 kGy range. It is also observed that the particle size of CaF2 nanostructure was significantly reduced by increasing Dy concentration. These results showed that Dy is a proper activator in the host of CaF2 nanostructure, providing a highly sensitive dosimeter in a wide range of exposures and also plays a role as a controlling agent for particle size growth.

Research paper thumbnail of Thermoluminescence of gamma rays irradiated LiF nanocubes doped with different elements

Journal of Luminescence, 2015

ABSTRACT Lithium fluoride (LiF) doped with proper activator is a highly sensitive phosphor, widel... more ABSTRACT Lithium fluoride (LiF) doped with proper activator is a highly sensitive phosphor, widely used as a dosimeter for ionizing radiations. This work reports on the thermoluminesence (TL) response of LiF nanocubes doped with different impurities. These nanocubes were synthesized by the co-precipitation method and characterized by different techniques. The dopants used in this study are Eu, Tb, Dy, Cu and Ag. The gamma radiation induced TL glow peaks are located in the temperature range 120–125 °C. These samples have different TL sensitivities, where Eu doped one is found to be the most TL sensitive. Further irradiations in the dose range from 10 Gy to 30 kGy were performed to LiF:Eu and the obtained result is explained using a proposed multilevel TL model. According to this model, Eu dopant (in Eu3+ ionic form) could induce shallow and deep electron traps in the host of LiF nanocubes. These traps differ in their response according to the doses. The optimum concentration of Eu ions in LiF host is found to be 0.2 mol%. It is also found that LiF nanocubes are thermally stable in the range of 30–400 °C with a single phase. This property along with the good sensitivity of Eu doped one makes this tissue equivalent nanomaterial a proper candidate for heavy dose measurement like swift heavy ions used in radiotherapy.

Research paper thumbnail of Evaluation of sunlight induced structural changes and their effect on the photocatalytic activity of V2O5 for the degradation of phenols

Journal of Hazardous Materials, 2015

Despite knowing the fact that vanadium pentoxide is slightly soluble in aqueous medium, its photo... more Despite knowing the fact that vanadium pentoxide is slightly soluble in aqueous medium, its photocatalytic activity was evaluated for the degradation of phenol and its derivatives (2-hydroxyphenol, 2-chlorophenol, 2-aminophenol and 2-nitrophenol) in natural sunlight exposure. The prime objective of the study was to differentiate between the homogeneous and heterogeneous photocatalysis incurred by dissolved and undissolved V2O5 in natural sunlight exposure. V2O5 was synthesized by chemical precipitation procedure using Triton X-100 as morphology mediator and characterized by DRS, PLS, Raman, FESEM and XRD. A lower solubility of ∼5% per 100ml of water at 23°C was observed after calcination at 600°C. The study revealed no contribution of the dissolved V2O5 in the photocatalytic process. In sunlight exposure, V2O5 powder exhibited substantial activity for the degradation, however, a low mineralization of phenolic substrates was observed. The initial low activity of V2O5 followed by a sharp increase both in degradation and mineralization in complete spectrum sunlight exposure, was further investigated that revealed the decrease in the bandgap and the reduction in the particle size with the interaction of UV photons (<420nm) as this effect was not observable in the exposure of visible region of sunlight. The role of the chemically different substituents attached to an aromatic ring at 2-positions and the secondary interaction of released ions during the degradation process with the reactive oxygen species (ROS) was also explored.

Research paper thumbnail of Sunlight induced formation of surface Bi2O4−x–Bi2O3 nanocomposite during the photocatalytic mineralization of 2-chloro and 2-nitrophenol

Applied Catalysis B: Environmental, 2015

The photocatalytic mineralization of 2-chlorophenol (2-CP) and 2-nitrophenol (2-NP) was investiga... more The photocatalytic mineralization of 2-chlorophenol (2-CP) and 2-nitrophenol (2-NP) was investigated using ␣-Bi 2 O 3 . The experiments were performed both in complete spectrum and in the visible region (420-800 nm) of the sunlight. The materials were fully characterized by means of UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM). ␣-Bi 2 O 3 showed considerably higher activity for the mineralization of 2-nitrophenol and 2chlorophenol under natural sunlight exposure, however still appreciable activity was observed in the visible region. Formation of surface nanocomposites Bi 2 O 4−x -Bi 2 O 3 was observed under sunlight irradiation due to the presence of UV light. The sunlight exposed Bi 2 O 3 , i.e. Bi 2 O 4−x -Bi 2 O 3 composite, showed excellent activity for the degradation and mineralization of 2-CP and 2-NP in the visible region of sunlight. A key role of both hydroxyl and superoxide anion radicals was evidenced in the degradation and mineralization processes under sunlight while only hydroxyl radicals were identified as major facilitators under visible light irradiation.

Research paper thumbnail of Synthesis and Characterization of Se35Te65−𝑥Ge𝑥 Nanoparticle Films and Their Optical Properties

Journal of Nanomaterials, 2012

Thin films of Se 35 Te 65−x Ge x (x = 0, 3, 6, 9, 12) nanoparticles were synthesized using therma... more Thin films of Se 35 Te 65−x Ge x (x = 0, 3, 6, 9, 12) nanoparticles were synthesized using thermal evaporation method. They were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and absorption and transmission spectra. XRD results show that these films are of amorphous nature, while SEM images show nanoparticles with average particle size around 30 nm. No significant changes are observed in morphology of the deposited films by changing concentrations of Te and Ge. The optical behaviors of these films have been studied using the absorption and transmission spectra in the spectral region 400-1100 nm. The absorption, extinction coefficients and refractive index were obtained and investigated in more detail. The optical band gap (E g ) values were also determined and are found to decrease from 0.83 to 0.69 eV by increasing the concentration of Ge from 0 to 12. The transmission spectra for the thin films of Se 35 Te 65−x Ge x nanoparticles show strong absorption at wavelength less than 500 nm and become highly transparent at wavelength above 800 nm. No significant changes in the transmission spectra are observed by increasing concentration of Ge. These results might be useful for development of optical disks and other semiconducting devices based on these nanochalcogenides.

Research paper thumbnail of J-E characteristics of Ni-catalysed multiwalled carbon nanotubes

International Journal of Nano and Biomaterials, 2009

Center of Nanotechnology, King Abdulaziz University, Jeddah, KSA and Department of Applied Scienc... more Center of Nanotechnology, King Abdulaziz University, Jeddah, KSA and Department of Applied Sciences and Humanities, Jamia Millia Islamia (Central University), New Delhi, India E-mail: zishanhk@rediffmail.com *Corresponding author ... Department of Physics, Jamia Millia ...

Research paper thumbnail of Syntheses and characterization of thin films of Te94Se6 nanoparticles for semiconducting and optical devices

Thin Solid Films, 2013

Thin films of Te 94 Se 6 nanoparticles were synthesized using the physical vapor condensation tec... more Thin films of Te 94 Se 6 nanoparticles were synthesized using the physical vapor condensation technique at different argon (Ar) pressures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy, absorption spectrum, photoluminescence (PL) and Raman spectroscopy. XRD results show that the as-grown films have a polycrystalline structure. SEM images display uniform nanoparticles in these films where the size increases from~12 to about 60 nm by decreasing Ar pressure from 667 to 267 Pa. These as-grown thin films were found to have direct band gaps, whose value decreases with increasing particle size. The absorption and extinction coefficients for these films were also investigated. PL emission spectra exhibit three bands peaking at 666, 718 and 760 nm, while Raman spectra displayed three bands located at 123, 143 and 169 cm −1 . No significant changes are observed in positions or intensities of these bands by decreasing the Ar pressure, except that of the last band of PL; where the intensity increases. The obtained results on this Te 94 Se 6 nanomaterial especially its controlled direct bandgap might be useful for development of optical disks and other semiconducting devices.