University of Malaya

About: University of Malaya is a education organization based out in Kuala Lumpur, Malaysia. It is known for research contribution in the topics: Population & Fiber laser. The organization has 25087 authors who have published 51491 publications receiving 1036791 citations. The organization is also known as: UM & Universiti Malaya.

Photoelectrochemical and photoresponsive properties of Bi2S3 nanotube and nanoparticle thin films

Abstract: Bi2S3 nanotubes and nanoparticle in the form of thin films were deposited on fluorine doped SnO2 (FTO) coated conducting glass substrates by Aerosol Assisted Chemical Vapor Deposition (AACVD) using tris-(N,N-diethyldithiocarbamato)bismuth(III), [Bi(S2CN(C2H5)2)3]2 (1) as a precursor. Thin films were deposited from solutions of (1) in either chloroform, dichloromethane, or a 1:1 mixture of chloroform and toluene at temperature between 350 to 450 °C and characterized by X-ray diffraction (XRD), UV−vis spectroscopy, field emission gun scanning electron microscopy (FEGSEM), and energy dispersive X-ray (EDX) analysis. FEGSEM images of films deposited from chloroform or dichloromethane exhibit well-defined and evenly distributed nanotubes with an average internal diameter of 40 nm. Films deposited from chloroform/toluene, on the other hand, have compact nanostuctured morphology. Bandgaps of 1.85 and 1.8 eV were estimated for nanotubes and nanoparticles, respectively, by extrapolating the linear part of the Tauc...

The green reduction of graphene oxide

Abstract: Graphene is an ultra-thin material, which has received broad interest in many areas of science and technology because of its unique physical, chemical, mechanical and thermal properties. Synthesis of high quality graphene in an inexpensive and eco-friendly manner is a big challenge. Among various methods, chemical synthesis is considered the best because it is easy, scalable, facile, and inexpensive. Different kinds of chemical reducers have been used to produce graphene sheets. However, some chemicals are toxic, corrosive, and hazardous. For this reason, researchers have been using different environmentally friendly substances (termed green reducers) to produce functional graphene sheets. This paper presents an overview and discussion of the green reduction of graphene oxide (GO) to graphene. It also reviews the characterization of GO and its oxide reduction through the analysis of different spectroscopic and microscopic techniques such as Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy.

An SEM-artificial-neural-network analysis of the relationships between SERVPERF, customer satisfaction and loyalty among low-cost and full-service airline

Abstract: The study examines the effects of SERVPERF on customer satisfaction and loyalty.A comparison between full service and low cost carriers is conducted.A predictive analytic approach via SEM-artificial-neural-networks is engaged.Multiple group analysis is used to assess the group invariance.63.1% and 55.6% of variance in customer satisfaction and loyalty are explained. There is a dearth of studies pertaining to the influence of SERVPERF on customer satisfaction and customer loyalty among low cost and full service airlines. Prior studies have measured service quality using the GAP-5 model with SERVQUAL; however this study offers a new perspective by using the SERVPERF with an SEM-artificial-neural-networks predictive analytic approach. This is different from the previous studies as it contributes to application of expert systems and intelligent algorithms in the context of low cost and full service airline. The findings revealed significant influences of SERVPERF dimensions on customer satisfaction towards customer loyalty with 63.1% and 55.6% variance explained. The implications from this research may help CEOs and managers of the air travel and tourism industry players to make better decisions in their resource planning stage, at the same time improving customer satisfaction and loyalty.

Influence of Mg Doping on ZnO Nanoparticles for Enhanced Photocatalytic Evaluation and Antibacterial Analysis

Abstract: In this research, a facile co-precipitation method was used to synthesize pure and Mg-doped ZnO nanoparticles (NPs). The structure, morphology, chemical composition, and optical and antibacterial activity of the synthesized nanoparticles (NPs) were studied with respect to pure and Mg-doped ZnO concentrations (0–7.5 molar (M) %). X-ray diffraction pattern confirmed the presence of crystalline, hexagonal wurtzite phase of ZnO. Scanning electron microscope (SEM) images revealed that pure and Mg-doped ZnO NPs were in the nanoscale regime with hexagonal crystalline morphology around 30–110 nm. Optical characterization of the sample revealed that the band gap energy (Eg) decreased from 3.36 to 3.04 eV with an increase in Mg2+ doping concentration. Optical absorption spectrum of ZnO redshifted as the Mg concentration varied from 2.5 to 7.5 M. Photoluminescence (PL) spectra showed UV emission peak around 400 nm. Enhanced visible emission between 430 and 600 nm with Mg2+ doping indicated the defect density in ZnO by occupying Zn2+ vacancies with Mg2+ ions. Photocatalytic studies revealed that 7.5% Mg-doped ZnO NPs exhibited maximum degradation (78%) for Rhodamine B (RhB) dye under UV-Vis irradiation. Antibacterial studies were conducted using Gram-positive and Gram-negative bacteria. The results demonstrated that doping with Mg ions inside the ZnO matrix had enhanced the antibacterial activity against all types of bacteria and its performance was improved with successive increment in Mg ion concentration inside ZnO NPs.

Activating mutations in STIM1 and ORAI1 cause overlapping syndromes of tubular myopathy and congenital miosis.

Abstract: Signaling through the store-operated Ca2+ release-activated Ca2+ (CRAC) channel regulates critical cellular functions, including gene expression, cell growth and differentiation, and Ca2+ homeostasis. Loss-of-function mutations in the CRAC channel pore-forming protein ORAI1 or the Ca2+ sensing protein stromal interaction molecule 1 (STIM1) result in severe immune dysfunction and nonprogressive myopathy. Here, we identify gain-of-function mutations in the cytoplasmic domain of STIM1 (p.R304W) associated with thrombocytopenia, bleeding diathesis, miosis, and tubular myopathy in patients with Stormorken syndrome, and in ORAI1 (p.P245L), associated with a Stormorken-like syndrome of congenital miosis and tubular aggregate myopathy but without hematological abnormalities. Heterologous expression of STIM1 p.R304W results in constitutive activation of the CRAC channel in vitro, and spontaneous bleeding accompanied by reduced numbers of thrombocytes in zebrafish embryos, recapitulating key aspects of Stormorken syndrome. p.P245L in ORAI1 does not make a constitutively active CRAC channel, but suppresses the slow Ca2+-dependent inactivation of the CRAC channel, thus also functioning as a gain-of-function mutation. These data expand our understanding of the phenotypic spectrum of dysregulated CRAC channel signaling, advance our knowledge of the molecular function of the CRAC channel, and suggest new therapies aiming at attenuating store-operated Ca2+ entry in the treatment of patients with Stormorken syndrome and related pathologic conditions.