19672 research outputs found
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Recent advances of aqueous two-phase flotation system for the recovery of biomolecules
No full textRecently, aqueous two-phase flotation system (ATPF) has developed as an established technique for separation and purification technology. This process that utilizes the integration principle of aqueous two-phase system and solvent sublation has wide applications in the extraction and purification of biomaterials in biotechnology field. This method has advantages of high recovery yield, high purity, environmentally friendly technique and economical. Additionally, ATPF is easily scalable to large volume which presents an appealing substitute that meets the conditions of industry processes. In the last decade, several researches were conducted to develop this separation process. With the utilization of various integrated method, diverse application of ATPF for numerous product extraction has been explored. This paper discusses the basic principles of ATPF and review on the latest literature works in the advancement of various application and integration of ATPF in the extraction of biomolecules. Comprehensive study on the application of ATPF and the future directions of this new technology in the biotechnology field will be discussed. © 2019 Elsevier B.V
Nanosecond pulse generation with a gallium nitride saturable absorber
No full textA mode-locked nanosecond Erbium-doped fiber laser (EDFL) was demonstrated using gallium nitrate (GaN) in the form of a polished crystal as a saturable absorber (SA). The GaN film exhibited a modulation depth of 2% with a saturable optical intensity of 0.46 MW/cm2. The laser directly produced nanosecond pulses with stable mode-locking operation at a pump threshold of 149.51 mW. The generated output pulses operated at a 1562 nm central wavelength with a pulse duration and a repetition rate of 485 ns and 967 kHz, respectively. The average output power was 3.068 mW at a pump power of 182.34 mW, corresponding to 3.1 nJ single pulse energy. These results indicate that GaN material has a promising application in ultrafast light generation. © 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Online purchasing: the role of web experience factors
No full textThis paper examines the effect of web experience factors such as usability, interactivity, trust and aesthetics derived from flow theory on purchasing intention. From 360 questionnaires distributed, 300 responses were gathered. Using logistic regression analysis, results indicate that usability, interactivity and trust are positively and significantly associated with purchasing intention whereas aesthetics is not. It seems that online retailers should adopt a targeted aesthetics approach in developing a web store depending on the type of merchandise and the markets approached. As such, retailers can lure new customers, retain existing ones and improve their attitudes toward web stores. Copyright © 2019 Inderscience Enterprises Ltd
Switchable erbium-doped fiber laser (EDFL) using non-adiabatic microfiber
No full textWe have investigated the operation principle of the switchable EDFL which stands for the erbium-doped fiber laser, where a non-adiabatic microfiber has been fabricated and used. Utilizing the flame-brushing technique, the optical microfiber has been fabricated and afterward, it has been inserted into the EDFL cavity, therefore by proposing the setup configuration, the single and multi-wavelength laser could be generated. By applying the different filtering effects of the microfiber, the results of a single wavelength laser (one set), dual-wavelength laser (three sets) and triple wavelength laser (two sets) could be generated over a wavelength range of 1560–1565 nm. The signal to noise ratio (SNR) of 42–50 dB is obtained from the experiment with acceptable wavelength and power fluctuation over the test period of 30 min. Proposed switchable EDFL shows tunable and stable single and multi-wavelength laser generation in C band region. © 2019 Elsevier Inc
Isolation of Oxoaphorpine Alkaloid from Bark of Cryptocarya Ferrea
No full textExtraction, isolation, identification and characterization of the compounds isolated from the bark of Cryptocarya ferrea yielded three known oxoaphorpine alkaloids. They are o-metilmoschatoline 1, ateroline 2 and subsesiline 3. Structural elucidation was established through spectroscopic methods 1D-NMR and 2D-NMR, UV, IR, and Mass Spectrometry and comparison with the published data. © 2019 Phcogj
Genesis of the Selinsing gold deposit, Peninsular Malaysia: Constraints from mineralogy, geochemistry and in situ sulfur isotope compositions of sulfides
No full textAs a renowned orogenic lode gold deposit, the Selinsing gold deposit is located in the Central Belt of Peninsular Malaysia. Geologically, the gold deposit is characterized by auriferous quartz veins and fine-grained gold minerals coexisted with sulfides, and the ore body is hosted by low-grade metamorphic sedimentary rocks and volcanic rocks. Furthermore, gold mineralization is closely related to tectonic deformation. Four main stages of vein formation have been identified, namely, (1) quartz-pyrite-arsenopyrite vein, (2) quartz-pyrite-gold vein, (3) quartz-stibnite-pyrite vein, and (4) quartz-chlorite vein. The occurrence of gold includes two types, i.e., visible gold and invisible gold. The former is featured by coarse-grained gold (millimeter-scale, such as auriferous quartz veins) and fine-grained gold (micron-scale, such as native gold, calaverite, and electrum), the latter is contained in pyrite and arsenopyrite in the form of nano-scale native gold particles (Au0) and lattice gold (Au1+). The geothermometer of arsenopyrite and chlorite as well as temperature-sulfur fugacity diagram indicate that the temperature and sulfur fugacity of hydrothermal fluid decrease gradually. Considering that the sulfur fugacity drops gradually and aqueous inclusions coexist with carbonic inclusions, it is inferred that sulfuration reaction in which sulfur is consumed to produce sulfides and fluid immiscibility or phase separation may be responsible for gold precipitation. Tested by LA-MC-ICP-MS, the in-situ sulfur isotope compositions of sulfides formed in different stages are homogenous (about −1 to 1‰) and the calculated H2S-dominated hydrothermal fluid is also consistent (about −2 to 0‰) in sulfur isotope compositions, which reflect the mantle or ultrabasic rock and basic rock or magmatic rocks may be a potential source of sulfur. Combined with possible source and tectonic evolution of Peninsular Malaysia, possible metallogenic processes are proposed to explain genesis of the Selinsing gold deposit and other gold deposits in the Central Belt, i.e., ore-forming fluid was differentiated from oceanic crust and/or fertilized mantle wedge, or ore-forming fluid may be sourced from concealed magmatic rocks that formed by subduction of the Palaeo-Tethys toward the East Malaysia block. © 2019 Elsevier B.V
Sizing and applications of battery energy storage technologies in smart grid system: A review
No full textDynamics of the world are changing, and people are preferring low cost and reliable power throughout the day. The addition of renewable energy to the existing system is also one of the ways to provide reliable and cheap electricity. The existing bottle neck in transmission lines, continuous contamination of the environment due to heavy reliance on fossil fuels, and the highly fluctuating cost of fossil fuel are few reasons for the widespread use of renewable energy technology. Energy storage technologies are the need of time and range from low capacity mobile storage batteries to high capacity batteries connected to the intermittent renewable energy sources. Selection of different battery types, each having distinguished characteristics in power and energy, depends on the nature of power required and delivered. This paper presents a detailed review of battery energy storage technologies pertaining to the latest technologies, benefits, sizing considerations, efficiency, cost, and recycling. An in-depth analysis in terms of advantages and limitations between the different types of batteries is discussed and compared. In terms of microgrid application, the economic benefits of battery sizing using optimization and probabilistic methods provide a potential solution during the design stage by taking into account various factors affecting the sizing of the battery such as the degradation rate, reliability, and battery placement. This paper ends with the discussion on the recyclability of these batteries and their impact on the environment. © 2019 Author(s)
High-quality Schistosoma haematobium genome achieved by single-molecule and long-range sequencing
No full textBackground: Schistosoma haematobium causes urogenital schistosomiasis, a neglected tropical disease affecting >100 million people worldwide. Chronic infection with this parasitic trematode can lead to urogenital conditions including female genital schistosomiasis and bladder cancer. At the molecular level, little is known about this blood fluke and the pathogenesis of the disease that it causes. To support molecular studies of this carcinogenic worm, we reported a draft genome for S. haematobium in 2012. Although a useful resource, its utility has been somewhat limited by its fragmentation. Findings: Here, we systematically enhanced the draft genome of S. haematobium using a single-molecule and long-range DNA-sequencing approach. We achieved a major improvement in the accuracy and contiguity of the genome assembly, making it superior or comparable to assemblies for other schistosome species. We transferred curated gene models to this assembly and, using enhanced gene annotation pipelines, inferred a gene set with as many or more complete gene models as those of other well-studied schistosomes. Using conserved, single-copy orthologs, we assessed the phylogenetic position of S. haematobium in relation to other parasitic flatworms for which draft genomes were available. Conclusions: We report a substantially enhanced genomic resource that represents a solid foundation for molecular research on S. haematobium and is poised to better underpin population and functional genomic investigations and to accelerate the search for new disease interventions. © 2019 The Author(s) 2019. Published by Oxford University Press
Reciprocating compressor valve damage estimation under varying speeds through the acoustic emission technique
No full textPurpose: The purpose of this paper is to examine the effect of reciprocating compressor speeds and valve conditions on the roor-mean-square (RMS) value of burst acoustic emission (AE) signals associated with the physical motion of valves. The study attempts to explore the potential of AE signal in the estimation of valve damage under varying compressor speeds. Design/methodology/approach: This study involves the acquisition of AE signal, valve flow rate, pressure and temperature at the suction valve of an air compressor with speed varrying from 450 to 800 rpm. The AE signals correspond to one compressor cycle obtained from two simulated valve damage conditions, namely, the single leak and double leak conditions are compared to those of the normal valve plate. To examine the effects of valve conditions and speeds on AE RMS values, two-way analysis of variance (ANOVA) is conducted. Finally, regression analysis is performed to investigate the relationship of AE RMS with the speed and valve flow rate for different valve conditions. Findings: The results showed that AE RMS values computed from suction valve opening (SVO), suction valve closing (SVC) and discharge valve opening (DVO) events are significantly affected by both valve conditions and speeds. The AE RMS value computed from SVO event showed high linear correlation with speed compared to SVC and DVO events for all valve damage conditions. As this study is conducted at a compressor running at freeload, increasing speed of compressor also results in the increment of flow rate. Thus, the valve flow rate can also be empirically derived from the AE RMS value through the regression method, enabling a better estimation of valve damages. Research limitations/implications: The experimental test rig of this study is confined to a small pressure ratio range of 1.38–2.03 (free-loading condition). Besides, the air compressor is assumed to be operated at a constant speed. Originality/value: This study employed the statistical methods namely the ANOVA and regression analysis for valve damage estimation at varying compressor speeds. It can enable a plant personnel to make a better prediction on the loss of compressor efficiency and help them to justify the time for valve replacement in future. © 2019, Emerald Publishing Limited
