19672 research outputs found
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Formaldehyde sensing using ZnO nanorods coated glass integrated with microfiber
No full textA proposed formaldehyde (CH2O) sensor is fabricated by exploiting evanescent wave on a glass surface coated with Zinc Oxide (ZnO) nanorods integrated with microfiber. The diameter of silica fiber is reduced by tapering using flame brushing technique to a waist diameter of 6 µm. The glass surface was coated with ZnO nanorods using hydrothermal synthesis method. A significant response to formaldehyde concentrations from 0 ppm to 0.18 ppm was observed due to strong chemisorption process and changeable refractive index of the ZnO nanorods coated glass surface. Thus, the output power of the proposed sensor has reduced linearly from −22.64 dBm to −24.24 dBm with sensitivity and resolution of 9.78 dBm/ppm and 0.0016 ppm respectively. Sensitivity improved by a factor of 3 and the resolution by a factor of 2.5 when the glass surface is coated as compared to uncoated glass surface. The proposed formaldehyde sensor exploit the distinctive features of strong evanescent wave from silica microfiber and surface absorption capability of ZnO nanorods coated glass surface which eased the handling procedure during the synthesis process and sensing applications. Based on the experimental result, the proposed sensor has demonstrated an excellent sensing performance as a formaldehyde sensor. © 2019 Elsevier Lt
Effect of High-cyclic Loads on Dynamic Response of Reinforced Concrete Slabs
No full textBridge reinforced concrete deck slabs are often subjected to various cyclic loadings—making regular checks for fatigue damage necessary. Several experiments on reinforced concrete structures were conducted to evaluate its mechanical fatigue behaviour. Nevertheless, adequate experimental investigations on its dynamic properties are still needed. This paper reports on the test performed on three identical reinforced concrete slabs, with different cyclic load number and after the cycles, the load was increased up to the static failure. Modal testing was performed after each step of loading to assess their dynamic performance using modal parameters (natural frequencies, mode shapes and damping ratios). Finite element model was used to predict the natural frequency of the reinforced concrete slabs and their reliability was checked through model updating. The results showed the intensity of fatigued structures causes significant changes to the modal parameters and structural loading capacity. The study explores how fatigued structure can be assessed from dynamic performance, and also can be quantified through its structural stiffness, ultimately offering a better way of using non-destructive modal testing in identifying its structural health as compared to conventional testing techniques. © 2019, Korean Society of Civil Engineers
Residual Toxicity of Insecticides to Neoseiulus fallacis (Acari: Phytoseiidae) in Apples
No full textNeoseiulus fallacis (Garman) is a predatory mite that is common in apple orchards and distributed throughout North America. However, N. fallacis may be susceptible to pesticides used for the management of crop pests. This study aimed to evaluate the temporal effects of commonly used insecticides on N. fallacis survival. Neoseiulus fallacis adults were exposed to field-aged residues, and mortality and lethal time were measured over 96 h of exposure. Carbaryl caused high mortality to N. fallacis and the shortest lethal time values (LT50), followed by spinetoram, with moderate lethal time values. Esfenvalerate, acetamiprid, chlorantraniliprole, and novaluron showed little to no lethality to N. fallacis following exposure to dry field-aged residues. The results of this study provide important field-relevant knowledge that is often void from laboratory-based studies, which can aid integrated pest management (IPM) decision-makers in apple production systems. © 2019 The Author(s). Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved
Proposed narrowband biphoton generation from an ensemble of solid-state quantum emitters
No full textWe explore a mechanism for producing time-frequency entangled photon pairs (termed a biphoton) from an ensemble of atom-like solid-state quantum emitters. Four distinct energy levels of the solid-state system render four spin-conserving optical transitions as observed in color centers. This feature opens up the possibility to generate a four-wave mixing biphoton based on an electromagnetic induced transparency (EIT) for long-coherence quantum communication as demonstrated in cold atomic systems. We propose a narrow EIT window below a lifetime-limited linewidth of a SiV− in diamond, assuming a few hundred MHz. Consequently, the EIT-induced narrowband guarantees biphoton coherence time to be at least a few tens of a nanosecond without a cavity. Assessing the criteria of solid-state parameters applicable to the existing biphoton model from cold atoms will accelerate solid-state biphoton source research. This study shows that a realization of negligible ground state dephasing of a solid-state sample will be a crucial step toward a solid-state biphoton generation for more than a 100 ns time scale with a subnatural atomic linewidth of a few MHz. © 2019 Optical Society of America
Improvement of 2-μm Thulium-Doped Fiber Lasers via ASE Suppression Using All-Solid Low-Pass Photonic Bandgap Fibers
No full textAll-solid photonic bandgap fibers (PBGFs) were designed and fabricated to work as low-pass filters in 2-μm region. They were used for manipulating thulium doped fiber laser (TDFL) operating in the 2-μm region via amplified spontaneous emission suppression. A sharp lasing peak at 1915 nm was achieved using a single-stage TDFL with full width at half maximum and optical signal-to-noise ratio of 0.3 nm and 39.5 dB, respectively. This lasing is achieved using the fabricated PBGF low-pass filter with cutoff wavelength at 1945 μm and loss of more than 25 dB. In this respect, the resultant TDFL performed better than the one that did not employ the low-pass filter. In this paper, we present a few representative cases involving the all-solid PBGF. We have shown that by increasing the diameter of the fabricated PBGF from 142 to 189 μm, their cutoffs related to their bandgaps shifted from 1727 nm toward longer wavelengths, 2079 nm. As a result, lasers with different wavelengths were generated within 2-μm region. © 1983-2012 IEEE
Microbiota and potential opportunistic pathogens associated with male and female fruit flies of Malaysian Bactrocera carambolae (Insecta: Tephritidae)
No full textBactrocera carambolae Drew & Hancock is an agricultural pest that causes considerable damage to various fruit crops in Southeast Asia and South America. We report here the bacterial communities associated with field-caught male and female adult flies from University Malaya campus. The microbiota was determined by targeted 16S rRNA gene (V3–V4 region) sequencing using the Illumina MiSeq. At 97% similarity, four bacterial phyla (with relative abundance of ≥1% in at least one specimen) – Bacteroidetes, Firmicutes, Proteobacteria, and Tenericutes – were recovered from the adult flies. Proteobacteria was the predominant phylum in all the samples, with the female flies (86.81 ± 6.57%) having higher mean relative abundance than the male flies (71.57 ± 18.37%). The Firmicutes was more abundant in the male flies (14.47 ± 17.30%) than female flies (0.69 ± 1.25%). There were in total seven classes, nine orders, 13 families, 23 genera, and 31 putative species. Thirteen genera had higher mean relative abundance in male flies, and nine in female flies. Klebsiella was the predominant genus in female flies, while Desulfovibrio was more abundant in some male flies. The mean relative abundances of the putative species Orbus sasakiae and Enterococcus moraviensis were significantly higher in male than female flies, while female flies had significantly higher mean relative abundance for Escherichia fergusonii and Klebsiella variicola. Alpha diversity indices indicated that the bacterial diversity varied within and between male and female flies, and the mean bacterial diversity was significantly higher in male flies. The differences in bacterial diversity and relative abundance may be reasonably attributed to stochastic processes, in part to environmental factors such as food resources and habitats. It is significant that several putative bacterial species recovered in the present study have not been reported in Bactrocera fruit flies. Sixteen of the 31 detected putative bacterial species are potential opportunistic pathogens of medical/public health importance
Electrodeposited reduced graphene oxide as a highly efficient and low-cost electrocatalyst for vanadium redox flow batteries
No full textAn electrochemically reduced graphene oxide was grown on carbon felt surface in a simple one-step electrodeposition process of graphene oxide and it was employed as a positive electrocatalyst of vanadium redox flow battery. The electrodeposited graphene-based nanocomposite on carbon felt presented outstanding electrochemical redox reversibility toward vanadium redox couple. Based on the cyclic voltammetry data and electrochemical impedance spectroscopy curves, the modified composite electrode possesses a huge amount of oxygen functional groups, high surface area, high electrical conductivity and excellent stability in compared to the pristine carbon felt electrode. The prepared electrode showed promising performance for vanadium redox flow battery as the energy efficiency was significantly enhanced by 12% at current density of 60 mA cm−2. This superior performance was probably due to the increase in the surface sites and fast electron transfer rate of the reduced graphene oxide
A comprehensive study on antidiabetic and antibacterial activities of ZnO nanoparticles biosynthesized using Silybum marianum L seed extract
No full textGreen synthesis of ZnO nanoparticles (NPs) using the plants’ extract and their potential application have driven a tremendous interest in recent years. This study reports a green microwave-assisted method for synthesis of ZnO NPs using Silybum marianum L. seed extract. Characteristics of the as-prepared sample was explored in terms of crystalline phase, morphology, composition, surface area, optical, and thermal properties. The particles of the biosynthesized sample (ZnO/extract) had smaller sizes than the chemically produced one (ZnO). The existence of biomolecules from Silybum marianum L seed extract linked to the ZnO/extract sample was approved by various analyses. The ZnO/extract sample was used for treating alloxan-induced diabetic rats and its efficiency was compared with ZnO, extract, and insulin treatments. For this purpose, the levels of blood glucose, insulin, total cholesterol, total triglyceride, and high-density lipoprotein were measured before and after treating with the studied treatment agents and compared with each other. Moreover, the antibacterial activities of both ZnO samples were investigated against E. coli to assess their potential antibacterial application. From the results, ZnO/extract NPs represented an outstanding performance in overcoming the diabetic disorders and good antibacterial activity against the studied bacteria
Modelling the utilization of cloud health information systems in the Iraqi public healthcare sector
No full textThe Iraqi healthcare sector has been suffering from health records management issues from the perspectives of low information technology integrity and data complexity. As a solution, cloud computing services can offer an alternative, low-cost, and reliable way to store, manage, and retrieve health-related data, as well as monitoring patients’ health conditions anywhere and anytime using any device with any platform. The migration to cloud services is not yet widespread in Iraqi health facilities due to various challenges, including security and privacy, legal policies, and implementation. For instance, there has been no research shedding light on the utilization of cloud computing services in Iraqi hospitals’ health information systems. This study proposed a model by defining the critical success factors influencing physicians’ confirmation and behavioral control toward utilizing cloud health information systems in Iraqi hospitals. The model's variables were statistically investigated by utilizing an online questionnaire. Data were collected from a probability sample of 259 physicians working in four Iraqi high-IT hospitals. The collected ordinal data were analyzed using the PLS-SEM approach as a nonparametric second-generation multivariate analysis. The results showed that the effects of system compatibility, system complexity, security, and privacy on physicians’ confirmation and behavioral control were statistically significant. Both confirmation and behavioral control had a positive effect on physicians’ utilization of the technology in the Iraqi hospitals. It is believed that such finding may help to aid the current understanding of cloud health systems in managing health data as well as providing the necessary recommendations for policy makers to direct healthcare professionals to continuously consider the use of modern information and communications technology in the workplace
CdSe/TiO2 nanotubes for enhanced photoelectrochemical activity under solar illumination: Influence of soaking time in CdSe bath solution
No full textIn the present study, nanotubular structure of cadmium selenide/titanium dioxide (CdSe/TiO2) was successfully prepared via chemical bath deposition (CBD) chemosynthesis method to improve photoelectrochemical activity under solar illumination. The results revealed that optimum CdSe dopants incorporated into TiO2 nanotubes played a crucial role in determining the photoelectrode performance in water splitting. It was found that synthesized CdSe/TiO2 nanotubes soaked at 30 min of CdSe precursor showed a maximum photocurrent density of 0.0016 A/cm2 with improvement of about 10% than that of pure TiO2 nanotubes under solar illumination. The presence of optimum contents of CdSe dopants incorporated into TiO2 nanotubes could act as efficient mediators for trapping photo-induced electrons and reduce the recombination losses of charge carriers significantly