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Abdullah G. Al-Sehemi

Bio: Abdullah G. Al-Sehemi is an academic researcher from King Khalid University. The author has contributed to research in topics: Density functional theory & Medicine. The author has an hindex of 32, co-authored 428 publications receiving 4838 citations. Previous affiliations of Abdullah G. Al-Sehemi include Center for Advanced Materials & Al-Azhar University.


Papers
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TL;DR: In this article, different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4) photocatalysts were synthesized by modified Solvothermal (MST) process with and without polysaccharide.
Abstract: Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4) photocatalysts were synthesized by modified Solvothermal (MST) process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV–visible (UV–vis) spectroscopy and N2 adsorption–desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590–619 cm−1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0–76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB) dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst.

183 citations

Journal ArticleDOI
TL;DR: In this article, a theoretical analysis of the NLO properties of sp2 hybridized carbon nanomaterials is presented, and the importance of several structural designs to tune NLO amplitudes is highlighted.
Abstract: Nonlinear optical (NLO) materials are the smartest materials of the era, and have the ability to generate new electromagnetic fields with changed frequencies, phases, and other physical properties. Recently, many cutting edge research reports have been focused on NLO materials especially on those which are composed of sp2 hybridized carbon nanostructures. As the carbon nanostructures are composed of abundant π-electrons and have significant delocalization, these are potential candidates for modern NLO materials. Generally, sp2 hybridized carbon nanostructures can be divided into zero-dimensional fullerenes, one-dimensional nanotubes and two-dimensional graphene nanoribbons and quantum dots etc. These dimensionally different carbon nanomaterials are promising candidates for a wide range of applications in next-generation nanotechnologies. In present feature article, we first briefly explain a theoretical structure–NLO property relationship based on perturbation theory and then elucidate the crucial factors to control the NLO responses. We put together the different random investigations of sp2 hybridized carbon nanostructures for NLO application by highlighting the importance of their several structural designs to tune NLO amplitudes. Furthermore, we make a comparative and updated analysis of the NLO properties of dimensionally different sp2 hybridized carbon nanomaterials i.e. fullerenes, carbon nanotubes, and graphene nanoribbons and quantum dots. Finally, we make a brief discussion about different aspects and opportunities to use the sp2 hybridized carbon nanomaterials as high performance NLO materials of the future. This review is a focused perspective based on different updated quantum chemical investigations about fullerenes, nanotubes and graphene nanoribbons and quantum dots for their possible use in nonlinear optical applications.

146 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the use of different catalysts derived from waste biomass in the biodiesel is presented, which is mainly based on the utilization of various catalysts, including carbon-based catalysts and solid acid catalysts.
Abstract: Biodiesel is produced through the process of transesterification of different edible and non-edible oils and animal fats. The process takes place either in the presence of a homogeneous or heterogeneous catalyst. A suitable catalyst is selected based on the amount of free fatty acid (FFA) content present in the oil. The major difference between homogeneous and heterogeneous catalysts is that the homogeneous catalysts are insensitive to the amount of free fatty acids present in the oil. Also, homogeneous catalysts are toxic, highly flammable, and corrosive. Besides, the use of homogeneous catalysts produces soaps as a by-product and a bulk of wastewater which requires additional pretreatment methods and expenses for proper disposal. The research on the biodiesel synthesis in the presence of heterogeneous catalysts (carbon-based catalysts) is continuously studied to achieve a suitable process to produce biodiesel and to improve fuel quality on an industrial scale. Heterogeneous catalysts have great significance in the biodiesel production because of their simple and less expensive manufacturing process, ease of separation, and high reusability. They can be prepared easily by functionalizing the carbon surface with acid or base. Carbon-based catalysts have a high surface area and porosity that can enhance the rate of the esterification/transesterification process. Also, solid acid catalysts can convert the low-quality feedstocks to biodiesel in the presence of active acidic sites. Besides, carbon-based catalysts can be produced through waste e.g. sugarcane bagasse and their use make the production of biodiesel “Greener” one. This review paper is mainly based on the utilization of different catalysts derived from waste biomass in the biodiesel. Under optimum conditions biodiesel (FAME) yields 90%–99% were reported in the literature.

91 citations

Journal ArticleDOI
TL;DR: Time dependent density functional theory (TD-DFT) calculations along with frontier molecular orbitals, density of states (DOS), second hyperpolarizability density analysis and molecular electrostatic potential (MEP) diagrams are used to trace the origin of electro-optical as well as structure property relationships.
Abstract: Using first-principle methods, several key electronic, optical and nonlinear optical properties are calculated for two recently synthesized chalcone derivatives i.e. (2E)-3-(4-methylphenyl)-1-(3-nitrophenyl)prop-2-en-1-one (comp.1) and (2E)-3-[4-(dimethylamino)phenyl]-1-(3-nitrophenyl)prop-2-en-1-one (comp.2). The calculation of dipole moment, polarizability , anisotropy of polarizability as well as second hyperpolarizability (usually considered as a signature for two photon absorption phenomenon) are performed using density functional theory methods at PBE0/6-311G** level of theory. The linear average polarizability for comp.1 and comp.2 are found to be 32.15×10-24 and 38.76×10-24esu, respectively. Similarly, the second hyperpolarizability amplitudes of comp.1 and comp.2 are found to be reasonably larger mounting to 79.31×10-36 and 181.36×10-36esu, respectively. The importance of donor end is determined by comparing p-methylphenyl group of comp.1 with that of N,N-dimethylaniline group of comp.2 that results a remarkable increase in its amplitude, which is ∼2 times larger as compared with that of comp.1 owing to the stronger donor-acceptor configuration of comp.2. Interestingly, a comparison of average static third-order nonlinear polarizabilities shows that amplitudes of comp.1 and comp.2 are ∼13 times and ∼29 times larger than that of para-nitroaniline (a typical standard push-pull NLO-phore) at the same PBE0/6-311G** level of theory, which indicates a real time NLO application of our titled compounds. Time dependent density functional theory (TD-DFT) calculations along with frontier molecular orbitals, density of states (DOS), second hyperpolarizability density analysis and molecular electrostatic potential (MEP) diagrams are used to trace the origin of electro-optical as well as structure property relationships.

90 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used a two-step precipitation polymerization method and used as adsorbent for removal of heavy metal ions such as Pb(II, Cu(II), Cd(II) and Cr(III) from aqueous medium.

89 citations


Cited by
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08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 Jan 2016
TL;DR: The principles of fluorescence spectroscopy is universally compatible with any devices to read and is available in the digital library an online access to it is set as public so you can download it instantly.
Abstract: Thank you very much for downloading principles of fluorescence spectroscopy. As you may know, people have look hundreds times for their favorite novels like this principles of fluorescence spectroscopy, but end up in malicious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some harmful bugs inside their desktop computer. principles of fluorescence spectroscopy is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the principles of fluorescence spectroscopy is universally compatible with any devices to read.

2,960 citations

01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

1,652 citations

Journal ArticleDOI
TL;DR: Criteria for choosing the optimum isotherm model is established through a critical review of different adsorption models and the use of various mathematically error functions such as linear regression analysis, nonlinear regressionAnalysis, and error functions for adsorption data optimization.

1,151 citations