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Orange-red-emitting Eu3+-doped Ca9Gd(PO4)7 phosphors have been obtained by a sol-gel technique. These phosphors, excited by UV (270 nm) and near UV light (394 nm), emit orange-red light in the range of 580–710 nm. The Ca9Gd(PO4)7:7 mol% Eu3+ phosphor annealed at 1100 °C shows the highest PL intensity. Judd-Ofelt analysis reveals that the neighbor surroundings of Eu3+ ions are asymmetric, and the lowest asymmetry value is found at the dopant ratio of 7 mol%. The optimal phosphor excited by the wavelength of 394 nm displays an excellent thermal stability (∼76.4 % at 160 °C) with an activation energy of 0.163 eV. The corresponding CIE chromaticity coordinates (x; y) and color purity are calculated to be (0.5849; 0.3635) and 84.6 %, respectively. The quantum efficiency values of the Ca9... |
In magnetic resonance imaging (MRI), the scan time for acquiring an image is relatively long, resulting in patient uncomfortable and error artifacts. Fortunately, the compressed sensing (CS) and parallel magnetic resonance imaging (pMRI) can reduce the scan time of the MRI without significantly compromising the quality of the images. It has been found that the combination of pMRI and CS can better improve the image reconstruction, which will accelerate the speed of MRI acquisition because the number of measurements is much smaller than that by pMRI. In this paper, we propose combining a combined CS method and pMRI for better accelerating the MRI acquisition. In the combined CS method, the under-sampled data of the K-space is performed by taking both regular sampling and traditional ... |
The energy demand has recently been increasing dramatically; thus, it is evident that scientists worldwide need to find out the solution to solve the above problem. Among these technologies, solar and wind power energy are the most potential source as alternatives to fossil fuels. However, these energy sources are not continuous and are therefore considered as additional sources. A regenerative fuel cell (RFC) is a type of fuel cell that can function as an electrolyzer and fuel cell; therefore, this system is an independent power source and overcome the drawbacks of the original fuel cell system. This research has built a system to control the entire regenerative fuel cell system's flow, temperature, and energy. The system uses electricity to produce hydrogen and oxygen for storage;... |
Bacterial exopolysaccharides (EPSs) are an essential group of compounds secreted by bacteria. These versatile EPSs are utilized individually or in combination with different materials for a broad range of biomedical field functions. The various applications can be explained by the vast number of derivatives with useful properties that can be controlled. This review offers insight on the current research trend of nine commonly used EPSs, their biosynthesis pathways, their characteristics, and the biomedical applications of these relevant bioproducts. |
In recent decades, drastic changes in global social-economic situations have led to significant shifts in the financial market for entrepreneurial firms, thus resulting in changes in entrepreneurial finance discipline. The current body of literature, despite its significant growth, has not provided an overview landscape of this research area. Consequently, this study aims to fill this gap by employing the bibliometric analysis of 6902 articles from 1970 to 2019 extracted from the Web of Science database. By doing so, this paper attempts to provide an overview of the discipline's research output, social and conceptual structure, and offer strategies facilitating the scientific development within the field. The findings indicate that entrepreneurial finance is a young and growing fiel... |
Water evaporation-induced electricity generation technology has become an extremely interesting issue recently for supplying both freshwater and electricity. This review concentrates on advances in the recent development of water evaporation-induced electricity generation systems for possible application in the Internet of Things, resistive switching memory, devices collecting big data. Additionally, its application in powering some small electronic devices, energy storage, electrochemical deposition and electrochemical cells are also specifically clarified in this work. We divided water evaporation-induced electricity generation systems into three classifications, including tandem devices, hybrid devices, and self-powered generators. The mechanism and application of each electricit... |
In this study, we present the fabrication of nitrile butadiene rubber/waste leather fiber (NBR/WLF) composites with different weight percentages of WLF and NBR (0/100, 20/80, 30/70, 40/60, 50/50, 60/40 wt/wt). WLF was prepared by cutting the scrap leathers from the waste product of the Vietnamese leather industry. Subsequently, in order to make the short fibers, it was mixed by a hammer mill. The characteristics of WLF/NBR composites such as mechanical properties (tensile strength, tear strength, hardness), dynamic mechanical properties, toluene absorption, and morphology were carefully evaluated. As a result, the tensile strength and tear strength become larger with increasing WLF content from 0 to 50 wt% and they decrease when further increasing WLF content. The highest tensile st... |
Economic research is vital for creating more suitable policies to facilitate economic growth. Employing a combination of descriptive and Bayesian analyses, this paper investigates the research landscape of the economics discipline in Vietnam, in particular, the leading affiliations in the field and how these institutions compare to each other in terms of productivity, the number of lead authors, new authors and publications' journal impact factor. We also examine the differences in the authors' productivity based on their age and gender. The dataset extracted from the SSHPA database includes 1,444 articles. The findings show that among top producers of economic research in Vietnam, seven are universities, leaving only one representative of research institutes. These top producers ac... |
It is shown for the first time that the deep eutectic solvent, DES, formed by acetylcholine chloride and urea can be successfully used for Ag recovery from the cathode powder of spent silver oxide batteries. This DES performs two important functions namely, as selective leaching liquor to extract Ag(I) ions from the remaining Ag2O, leaving intact the metallic Ag in the solid phase, and as electrolytic bath for silver electrodeposition onto a glassy carbon electrode or graphite. Using potentiodynamic and potentiostatic electrochemical measurements, it was possible to quantify both: the Ag(I) leaching rate and the concentration of Ag(I) ions leached after 24 h. From this value, it was possible to estimate that about 7% of the original mass of the cathode powder corresponds to Ag2O and... |
Although Vietnam has been successful in the fight against the first wave of COVID-19, domestic outbreaks have continued to occur. Given university students constitute a significant proportion of the population in Vietnam, to improve the prevention and control of COVID-19 in Vietnam and comparable countries, we examined their knowledge, attitude, and practice (KAP) towards face mask use which is an important preventive measure and the association between the levels of COVID-19 knowledge and KAP towards face mask use. A cross-sectional survey was conducted on all students studying at Phenikaa University, Hanoi, using a self-developed questionnaire consisted of 42 questions regarding KAP towards face mask use as well as reuse of cloth mask, and COVID-19 knowledge. Among 728 participant... |
