Field emission property of ZnO nanowires prepared by ultrasonic spray pyrolysis

The field emission property of cold cathode emitters utilizing the ZnO nanowires with various conditions prepared by ultrasonic spray pyrolysis technique was discussed. It is found that the emission current was enhanced in the emitters having higher aspect ratio as well as smaller sheet resistance. Applying of post-annealing process, utilization of additional Mo back electrode in the cathode, and coating of Moon the ZnO nanowires resulted in the improvement of the emission current and lowering the threshold voltage. A threshold voltage of about 5.5 V/mu m to obtain 1.0 mu A/cm(2) was achieved in the sample prepared at the growth temperatures varying continuously from 250 degrees C to 300 degrees C. (C) 2015 Elsevier Ltd. All rights reserved.ArticleSUPERLATTICES AND MICROSTRUCTURES. 84:144-153 (2015)journal articl

Position-selective growth of ZnO nanowires by ultrasonic spray pyrolysis

Position-selective growth of ZnO nanowires was realized by utilizing a patterned soda-lime glass layer. The soda-lime glass layer contributes as the origin of nucleation sites for the growth of nanowires in economically viable ultrasonic spray pyrolysis technique. The formation of nanowires took place with good reproducibility at relatively low substrate temperatures of 250-400 degrees C when the soda-lime glass matrix was present at the surface of substrates, and such a nitrate compound as nitric acid or nitrate salt was mixed in the precursor solutions. Based on this technique, the position-selective growth and density-controlled growth of ZnO nanowires can be performed on various types of substrate. The presence of a CaO compound in the glass matrix was revealed as an important condition to grow the nanowires. (C) 2009 Elsevier B.V. All rights reserved.ArticleJOURNAL OF CRYSTAL GROWTH. 311(20):4499-4504 (2009)journal articl

Synthesis of optical quality ZnO nanowires utilizing ultrasonic spray pyrolysis

ZnO nanowires were grown by an ultrasonic spray pyrolysis technique. The aspect ratio and size of the wire were dependent mainly on the pH value of a precursor solution and the growth temperature. By high-resolution transmission electron microscopic analysis and photoluminescence measurements, it was confirmed that the nanowires are monocrystalline with good optical quality.ArticleJOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS. 20:341-345 (2009)journal articl

Synthesis of a cuprite thin film by oxidation of a Cu metal precursor utilizing ultrasonically generated water vapor

A Cu2O thin film of cuprite crystal structure was fabricated via a decomposition reaction of water vapor generated by ultrasonic vibration. The thin film, which was grown on a soda-lime glass substrate at 530 degrees C, exhibited a prominent (111) preferred orientation with an optical bandgap of about 2.1 eV and resistivity of 2.81 x 10(4) Omega cm. Generation of H-2 gas during the reaction process contributed to suppressing the growth of impurity tenorite phase. In a conventional process of thermal oxidation, the formation of the cuprite phase was always accompanied by that of the tenorite phase due to an excess oxygen exposure near the surface of the films.ArticleTHIN SOLID FILMS. 556:211-215 (2014)journal articl

Caregiver experience and perceived acceptability of a novel near point-of-care early infant HIV diagnostic test among caregivers enrolled in the PMTCT program, Myanmar: A qualitative study

Background: The majority of HIV infection among children occurs through mother-to-child transmission. HIV exposed infants are recommended to have virological testing at birth or 4–6 weeks of age but challenges with centralized laboratory-based testing in Myanmar result in low test- ing rates and delays in result communication and treatment initiation. Decentralized point- of-care (POC) testing when integrated in prevention of mother-to-child transmission of HIV (PMTCT) services, can be an alternative to increase coverage of early infant diagnosis (EID) and timely engagement in HIV treatment and care. Aim: This paper aims to explore experiences of caregivers of HIV-exposed infants enrolled in the PMTCT program in Myanmar and the perceived acceptability of point-of-care EID testing compared to conventional centralised laboratory-based testing. Methods: This is a sub-study of the cluster randomised controlled stepped-wedge trial (Trial registra- tion number: ACTRN12616000734460) that assessed the impact of near POC EID testing using Xpert HIV-1 Qual assay in four public hospitals in Myanmar. Caregivers of infants who were enrolled in the intervention phase of the main study, had been tested with both Xpert and standard of care tests and had received the results were eligible for this qualitative study. Semi-structured interviews were conducted with 23 caregivers. Interviews were audio recorded, transcribed verbatim and translated into English. Thematic data analysis was undertaken using NVivo 12 Software (QSR International). Results: The majority of caregivers were satisfied with the quality of care provided by PMTCT ser- vices. However, they encountered social and financial access barriers to attend the PMTCT clinic regularly. Mothers had concerns about community stigma from the disclosure of their HIV status and the potential consequences for their infants. While medical care at the PMTCT clinics was free, caregivers sometimes experienced financial difficulties associated with out-of-pocket expenses for childbirth and transportation. Some caregivers had to choose not to attend work (impacting their income) or the adult antiretroviral clinic in order to attend the paediatric PMTCT clinic appointment. The acceptability of the Xpert testing pro- cess was high among the caregiver participants and more than half received the Xpert result on the same day as testing. Short turnaround time of the near POC EID testing enabled the caregivers to find out their infants’ HIV status quicker, thereby shortening the stressful wait- ing time for results. Conclusion: Our study identified important access challenges facing caregivers of HIV exposed infants and high acceptability of near POC EID testing. Improving the retention rate in the PMTCT and EID programs necessitates careful attention of program managers and policy makers to these challenges, and POC EID represents a potential solution

Cu2ZnSn(SxSe1-x)4 Thin-Film Solar Cells Utilizing Simultaneous Reaction of a Metallic Precursor with Elemental Sulfur and Selenium Vapor Sources

A Cu2ZnSn(SxSe1-x)(4) (CZTSSe) solid alloy was prepared by reacting a metallic precursor with sulfur and selenium in a closed tube simultaneously. It was confirmed that the CZTSSe alloy could be synthesized over the whole compositional range and its lattice transformation was in good agreement with Vegard's law. The crystal grain size and electrical conductivity were enhanced when the selenium content was increased. In a CdS/CZTSSe heterojunction solar cell, the photovoltaic efficiency was improved due to the enhancement of the short-circuit current in accordance with the narrowing of the optical bandgap of the CZTSSe absorber. (c) 2012 The Japan Society of Applied PhysicsArticleAPPLIED PHYSICS EXPRESS. 5(8): 81201 (2012)journal articl

Island health review, progress and the way forward in the Western Pacific Region

Island health differs from other health care systems, particularly in that there are limited resources and referral faculties available. With globalisation and climate change, island populations have become increasingly vulnerable to natural disasters and global pandemics. This study will identify, explore, compare and report on island health issues facing in the western Pacific, before making appropriate recommendations. A review of selected health indicators in Pacific islands was collected from the World Health Organization (WHO) and other publicly available resources. In the Pacific region, 15 islands saw lower health expenditure (<US $500), one physician and two to six nurses per 1,000 people (fall below WHO recommendation), lower life expectancy (60-70 years), higher fertility rates (2.5 to 6.4 children per women, excepting Palau), and higher adolescent fertility rates (23 to 88 children per 1,000 girls, excepting Tonga). Island populations also suffer a higher disease burden per 100,000 people, with TB, malaria, and non-communicable diseases contributing to elevated mortality rates throughout much of the region. This article highlights four areas: the sustainable development of the health workforce, improved maternal and antenatal health care provisioning, and selective communicable and non-communicable disease control. However, there are some limitations especially under reporting of maternal health data and generalization effect of reported data