19672 research outputs found
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New class of lead free perovskite material for low-cost solar cell application
No full textIn this paper, we fabricate a new class of perovskite sensitizer material for photovoltaic application. This is not only low-cost perovskite material but also is a non-toxic material for solar cell as compared to the conventional materials used in PSC. Detailed procedure of synthesis of CH 3 NH 3 SnCl 3 material and its application in fabrication of PSC is presented in the article. Perovskite material i.e. methyl ammonium tin tri-chloride (CH 3 NH 3 SnCl 3 ) was prepared by direct deposition of equimolar concentration of CH 3 NH 3 Cl and tin chloride (SnCl 2 ) in dimethylformamide (DMF) solution. X-ray diffraction pattern (XRD) of the material confirms the formation of perovskite structure whereas, UV–vis absorption spectroscopy shows the absorption range of these material. Crystal formation of the perovskite is confirmed from the scanning electron microscope (SEM). A comparison of the crystal and powder form of perovskite material is discussed in depth in terms of structural, optical and electrical properties
Mediating impact of fan-page engagement on social media connectedness and followers purchase intention
No full textPurpose: The purpose of this paper is to identify the mediating effect of fan-page followers’ engagement activities and moderating role of followers’ demographic profile and trust level on their purchase intention. Design/methodology/approach: This study utilised the customer engagement behaviour and consumer involvement theory as a foundation to explore the impact of variables. Structural equation modelling was utilised to test the model with the data collected from 307 Facebook fan pages’ followers of five Malaysian companies. Findings: It was shown that following fan pages will influence fan page engagement, which in turn affects purchase intention and social media connectedness. Further analysis indicated that the impact of “follow” and “engagement” on purchase intention differs between genders, ages, level of trust and income. Research limitations/implications: The study serves as a basic fundamental guideline for academics and researchers to interpret the concept of following fan pages and engagement actions and its effects on purchase intention and social media connectivity, as well as opening a vast area of unexplored researches on the subject of social media. Practical implications: The research provides information for business-to-consumer companies in utilising fan page based on user categories. Originality/value: This study proposes the application of an empirically tested framework to the fan-page follow actions. The authors argue that this framework can provide a useful foundation for future social commerce research. The results would help academics be aware of fan page and its user’s engagement actions, which will provide a new avenue of research
An 8 cm long holmium-doped fiber saturable absorber for Q-switched fiber laser generation at 2-µm region
No full textWe demonstrate a Q-switched all-fiber laser operating at 2-µm region by adding a piece of 8 cm long holmium doped fiber (HDF) as a fiber saturable absorber (SA) in Thulium doped fiber laser (TDFL) ring cavity. Doping of Ho ions into yttria-alumina silica glass was done through conventional Modified Chemical Vapor Deposition (MCVD) technique in conjunction with solution doping process. The fabricated HDF has a linear absorption of 3 dB with a core diameter and a numerical aperture of 10 µm and 0.18, respectively. A self-started Q-switching operation begins at 418 mW pump level and continually dominant until 564 mW pump level. As the pump power increases, stable pulse train presence from 30.61 kHz to 38.89 kHz while the pulse width reduces from 3.18 µs to 2.27 µs. Both maximum output power and maximum peak power are obtained at 5.05 mW and 57.2 mW, respectively, while the maximum pulse energy is calculated to be 129 nJ. The signal-to-noise ratio (SNR) of the fundamental frequency is 50 dB. Our work may contribute to the discovery of stable, robust, and economic SA for pulse fiber laser generation at 2-µm region
Preparation and characterization of Ag nanoparticles decorated with ZnO microstructures for the catalytic photodegradation of methylene blue dye under UV light irradiation (Penyediaan dan pencirian Ag berstruktur nanopartikel diubahsuai dengan ZnO berstruktur mikro untuk penurunan fotokatalisis pewarna metilena biru di bawah sinar UV)
No full textAg nanoparticles (AgNPs) decorated with ZnO microstructures was prepared by sol-gel method at different Ag concentration. The structures, composition and morphology of the samples were characterized by X-ray diffraction (XRD), electron dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM). FESEM images shows that the samples were composed of Ag and ZnO with the particles size ranging from 100 to 500 nm. EDS analysis confirmed that atomic % increases as higher molar concentration applied with value of 5.6 at.% and 16.1 at.% for sample 0.05M and 0.1M AgNPs decorated ZnO microstructures. Methylene blue (MB) dye was used as a representative of dye pollutant to conduct the catalytic photodegradation activity. The AgNPs decorated with ZnO particles exhibited a better photocatalytic activity than the pure ZnO particles. The results show that an increasing of photodegradation rate constant, k was obtained when higher concentration of Ag was applied to the ZnO with value of 0.016, 0.026 and 0.032 min-1 for pure ZnO, 0.05M AgZnO and 0.1M AgZnO nanoparticles, respectively. The increased of k value in the presence of Ag was due to the prolonged lifetime of the photogenerated electron hole pairs in ZnO as a result of Ag nanoparticles acting as electron sink
Identification of Novel Cytotoxic Peptide KENPVLSLVNGMF from Marine Sponge Xestospongia testudinaria, with Characterization of Stability in Human Serum
No full textResistance and side effects are common problems for anticancer drugs used in chemotherapy. Thus, continued research to discover novel and specific anticancer drugs is obligatory. Marine sponges hold great promise as a source of potent cytotoxic peptides with future applications in cancer treatments. This study aimed to purify and identify cytotoxic peptides from the protein hydrolysates of the giant barrel sponge Xestospongia testudinaria, guided by a cytotoxicity assay based on the human cervical cancer cell line (HeLa). Comparison among trypsin, chymotrypsin, papain and alcalase hydrolysates of X. testudinaria revealed papain hydrolysate (PH) to be the most active. PH was purified consecutively by membrane ultrafiltration, gel filtration chromatography, and reversed-phase high performance liquid chromatography (RP-HPLC). Following liquid chromatography-tandem mass spectrometric analysis, two peptides were identified from the most cytotoxic RP-HPLC fraction: KENPVLSLVNGMF and LLATIPKVGVFSILV. Between the two, only the synthetic peptide KENPVLSLVNGMF showed cytotoxicity toward HeLa cells in a dose-dependent manner. KENPVLSLVNGMF (EC50 0.67 mM) was 3.8-fold more cytotoxic compared with anticancer drug 5-fluorouracil (EC50 2.56 mM). Furthermore, KENPVLSLVNGMF show only marginal 5% cytotoxicity to Hek293, a non-cancerous, human embryonic kidney cell line, when tested at 0.67 mM. The half-life of the peptide was 3.2 ± 0.5 h in human serum in vitro, as revealed by RP-HPLC analyses. These results suggest that KENPVLSLVNGMF identified from X. testudinaria papain hydrolysate has potential applications as peptide lead in future development of potent and specific anticancer drugs
Influence of Mg Doping on ZnO Nanoparticles for Enhanced Photocatalytic Evaluation and Antibacterial Analysis
No full textIn 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
Design and analysis of slotted core photonic crystal fiber for gas sensing application
No full textIn this paper, a slotted core photonic crystal fiber (PCF) has been designed. A rigorous numerical investigation has been done over the wider range of the wavelength from 1.30 µm to 2.0 µm near inferred region (IR). By employing full vectorial finite element method (FV-FEM) having completely circular anisotropic perfectly matched layer (C-PML) different optical parameter such as nonlinearity, confinement loss, sensitivity, beat length, V-parameter and splice loss of the modeled PCF have been uncovered. The investigated upshot testifies that the birefringence gained at the order of 10 −2 . Nevertheless, the proposed fiber experienced with the lower order (1.26 × 10 −5 dB/m) of confinement loss with a higher order of nonlinearity 54.33 W −1 km −1 at simultaneously at the operating optical wavelength λ = 1.33 µm. Moreover, the impacts of the geometric parameters have been turned on birefringence, nonlinearity and confinement losses which are also analyzed in detail. The proposed PCF model with investigated results provides stronger evidence that, the structure will play a substantial role in the area of optical waveguides as well as optical devices or instrumentations
Analysis of Current Harmonics Compensation and the Effect of Frequency Variation for Single-Phase Stand-Alone PV Inverters using PR Controller
No full textThis paper presents the analysis of current harmonics compensation using the proportional-resonant controller for single-phase stand-alone photovoltaic inverter applications. The effect of frequency variation in the reference signal to the controller performance was also analyzed. The controller parameters (K p , K i , and ω c ) and the inductor-capacitor (LC)-filter parameters are optimally selected to obtain a very low current total harmonic distortion. The control algorithm was implemented using a low-cost digital signal processor (DSP) TMS320F28335 eZdsp development board. Both simulation and experimental results validate the performance and the effectiveness of the control technique used
Developing a Quality-Embedded EVM Tool to Facilitate the Iron Triangle in Architectural, Construction, and Engineering Practices
No full textIn modern architecture, engineering, and construction (AEC) practices, the Iron Triangle of schedule, cost, and quality remains the key measurement to gauge project success. Existing tools do not work well at monitoring all three measures of the Iron Triangle, resulting in a huge cost and time overrun, and the existing functionality of Earned Value Management (EVM) covers only time and cost, but not quality. Thus, this study aims to develop a quality extension to EVM that caters to quality measurement. Firstly, this research introduced a measurable index and developed a new quality assessment method named the Quality Performed Assessment Method (QPAM) through a quantitative approach. Subsequently, a new tool named Earned Quality Value Management (EQVM) was developed to manage the Iron Triangle in a single reporting setting. The QPAM and EQVM were validated through three tiers of validation processes, namely, a pilot run to test its functionality in a conceptual model, a scenario analysis to identify its sensitivity, and a real case study to validate its functionality. QPAM and EQVM performed satisfactorily in systematic reporting and monitoring enhancement. This single reporting tool enables project stakeholders to make cross-comparisons and gain more insight into the project portfolio. Academically, this research minimized the gap among Iron Triangle management, quality management, and project portfolio management. Practically, this research developed a method for Iron Triangle control on a daily basis for both a single project and a portfolio
The Influence of Career Adaptability and Work Happiness on ICT Professionals' Intention to Leave
No full textStudies on intention to leave are important to distinguish between stayers and leavers in the organization. This article assesses whether career adaptability and work happiness can be the factors that may have influence on intention to leave among ICT professionals in Malaysia. Samples consist of 393 participants who work in ICT related companies and data were analyzed using structural equation modelling (SEM). The results indicate that individual will have lower level of intention to leave due to higher level of career adaptability and work happiness