Najran University

About: Najran University is a education organization based out in Najrān, Saudi Arabia. It is known for research contribution in the topics: Photocatalysis & Nanoparticle. The organization has 751 authors who have published 1809 publications receiving 28233 citations.

Impact of the annealing temperature on perovskite strontium doped neodymium manganites nanocomposites and their photocatalytic performances

Abstract: In the present work, Nd 0.6 Sr 0.4 MnO 3 nanocomposite perovskite has been synthesized using sol-gel method in the presence of polyethylene glycol and citric acid. As-synthesized Nd 0.6 Sr 0.4 MnO 3 perovskite was annealed at different temperatures (500–1150 °C). The obtained perovskite Nd 0.6 Sr 0.4 MnO 3 nanocomposites exhibit wide optical absorption in the UV–visible range with low bandgap values ∼ 2–2.98 eV relied on annealing temperatures. The crystalline size of the annealed sample at 500 °C was 55 nm increased with boosting temperature to 168 nm at 1150 °C. The newly prepared perovskite has been assessed by MB photodegradation under visible light. Our findings reveal that, Nd 0.6 Sr 0.4 MnO 3 perovskite with 26.18% orthorhombic and 73.82% monoclinic phases annealed at 500 °C is a superior photocatalyst than that of Nd 0.6 Sr 0.4 MnO 3 perovskite containing 82.22% cubic and 17.78% orthorhombic phases annealed at 1150 °C. 100% of MB could be photodegraded by the Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 500 °C. However, with the increase annealing temperature to 1150 °C, the photocatalytic efficiency was reduced to 60%. The overall photodegradation rate of Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 500 °C is significantly 3-times higher than that of Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 1150 °C. The superiority of the perovskite Nd 0.6 Sr 0.4 MnO 3 annealed at 500 °C is attributed to the double phases formed (monoclinic/orthorhombic) framework, high crystallinity, and the high distortion of the Mn-O polyhedron. It is believed that the high visible-light absorption, lattice distortion and narrow band gap are considered to be the key factors for the high photocatalytic activity of the obtained Nd 0.6 Sr 0.4 MnO 3 perovskite annealed at 500 °C.

Modeling of multifunctional donor-bridge-acceptor 4,6-di(thiophen-2-yl)pyrimidine derivatives: a first principles study.

Abstract: We have modeled multifunctional compounds by pi-elongation and push-pull strategy from the 4,6-di(thiophen-2-yl)pyrimidine. The ground state geometries have been optimized by density functional theory while excited state geometries were optimized by time dependent density functional theory (TDDFT). Structure-property relationship, electronic, optical and charge transfer properties (ionization potential, electron affinity and reorganization energies) were computed and discussed. By TDDFT absorption and emission have been calculated. The computed parameters were compared with available experimental data. The long-range corrected functional (LC-BLYP) is overestimating the highest occupied and lowest unoccupied molecular orbital energies, energy gaps while underestimating the absorption and fluorescence wavelengths. The B3LYP is good to reproduce the experimental data. The intra-molecular charge transfer has been observed from highest occupied molecular orbitals to lowest unoccupied molecular orbitals. The strong electron withdrawing and electron donor groups efficiently reduce the energy gaps. The decrease injection barrier and smaller reorganization energies are revealing that our designed derivatives would be efficient hole as well as electron transfer materials. These derivatives would be good light emitters e.g. blue, green, orange, red and near IR. The predicted values showed that the designed derivatives would be efficient for the organic field effect transistors, photovoltaics and light emitters.

Biologically Synthesized Silver Nanoparticles for Enhancing Tetracycline Activity Against Staphylococcus aureus and Klebsiella pneumoniae

Abstract: Phytochemical content of plant extracts can be used effectively to reduce the metal ions to nanoparticles in one-step green synthesis process. In this study, six plant extracts were used for the synthesis of silver nanoparticles (AgNPs). Biologically synthesized AgNPs was characterized using UV-Vis Spectrophotometer, Field Emission Scanning Electron Microscope (FE-SEM), X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared (FTIR) spectroscopy. The individual and combined effects of AgNPs and tetracycline against S. aureus and K. pneumoniae were assessed. Ginger, onion and sidr extracts supported AgNPs formation while arak, garlic and mint extracts failed to convert the silver ions to AgNPs. The present findings revealed significant differences between the tested plant extracts in supporting AgNPs synthesis. AgNPs synthesized by ginger showed the highest individual and combined activity against tested strains followed by AgNPs prepared by sidr then that synthesized by onion. AgNPs significantly enhanced tetracycline activity (p≤0.05) against S. aureus and K. pneumoniae. The results of this study demonstrated that the combination of tetracycline and biologically synthesized AgNPs presented a useful therapeutically method for the treatment of bacterial infection and counterattacking bacterial resistance.