Abstract
Aiming to design a catalyst for stable electrooxidation of water at low pH, the present work explores the properties and structural features of electrodeposited composite oxides based on Bi ...and Co, which were anticipated to provide stability and catalytical activity, respectively. Materials deposited as very thin (
ca
50 nm) films on F‐doped SnO
2
(FTO) substrate do not initially exhibit high activity in 0.1 M H
2
SO
4
, but are activated during operation through the electrooxidatively‐induced enrichment of the catalytic surface with Co and Sn oxides. The latter originate from the FTO support and are identified as an important component of the catalyst through control experiments with a Sn‐free substrate and with Sn
2+
intentionally added at the electrodeposition stage. A distinctive feature of the Co−Bi−Sn‐based electrocatalyst is the slow but persistent improvement in the activity during operation in 0.1 M H
2
SO
4
at both ambient and elevated (60 °C) temperatures, which contrasts with the continuously degrading behaviour of state‐of‐the‐art oxygen evolution catalysts at low pH. This is demonstrated by 9‐day‐long galvanostatic tests at 10 mA cm
−2
, during which the Co−Bi−Sn‐based thin film catalyst shows no degradation and sustains stable water oxidation at
ca
1.9 V
vs
. reversible hydrogen electrode. The effects of tin leaching from the support detected herein might have implications to other acidic water oxidation catalysts supported on high‐surface area doped SnO
2
materials.
The capping agent plays a critical function in anisotropic crystal growth to induce polyhedral morphology of a nanocrystal. Uniform and single-crystalline α-Fe2O3 polyhedral nanoparticles in the ...hexagonal single crystal system named truncated hexagonal bipyramid for the first time were successfully synthesized by a facile one-step hydrothermal method with the aid of carboxymethyl cellulose and hydrazine molecules. The appearance and crystal structure of these iron oxide nanoparticles were characterized in detail by physicochemical methods. The results show that the as-synthesized α-Fe2O3 particles are bound by 12 same-side crystalline facets {101} and two other same facets {001} at the tops. These obtained iron oxide particles belong to a pure hematite phase, and the particle size is around 400 nm. The optical property of the as-synthesized product was analyzed, and the determined indirect band gap value E g is 2.08 eV. The magnetic property studies of truncated hexagonal bipyramid hematite particles have shown that this kind of α-Fe2O3 possess a weak ferromagnetism under the T M, and the saturation points do not reach up to the maximum applied magnetic field. Role of the reactants was discussed and investigated systematically in the work. Furthermore, a schematic illustration for the probable formation of this α-Fe2O3 morphology in whole of the synthetic process was also proposed.
The methods for leaf-derived callus induction, callus proliferation, adventitious shoot induction and plant regeneration of Vietnamese ginseng (Panax vietnamensis Ha et Grushv.) were examined. In ...this study, callus induction was formed on both medium containing 2, 4-dichlorophenoxyacetic acid (2, 4-D) alone or in combination with thidiazuron (TDZ). The highest callus induction frequency was obtained on Murashige and Skoog (MS) medium supplemented with 1.0 mg/l 2, 4-D and 0.2 mg/l TDZ. The best callus proliferation medium was Schenk and Hildebrandt (SH) supplemented with 0.2 mg/l TDZ and 1.0 mg/l 2, 4-D. The maximum callus-derived shoot number (8.2) was obtained on SH medium supplemented with 50 g/l sucrose in combination with 2.0 mg/l 6-benzylaminopurine (BA). The most successful rooting of regenerated adventitious shoots was obtained on SH medium with 1.0 mg/l alpha -naphthalene acetic acid (NAA). Plantlets were successfully acclimatized without growth chamber facility on Ngoc Linh mountain with a survival rate of 85% after two months. On the other hand, substantial increase of root length was observed. This study describes an efficient method for in vitro regeneration of P. vietnamensis, which could be considered for large-scale multiplication and propagation of this important medicinal plant.
The COVID-19 pandemic has imposed a heavy burden on health care systems and governments. Health literacy (HL) and eHealth literacy (as measured by the eHealth Literacy Scale eHEALS) are recognized as ...strategic public health elements but they have been underestimated during the pandemic. HL, eHEALS score, practices, lifestyles, and the health status of health care workers (HCWs) play crucial roles in containing the COVID-19 pandemic.
The aim of this study is to evaluate the psychometric properties of the eHEALS and examine associations of HL and eHEALS scores with adherence to infection prevention and control (IPC) procedures, lifestyle changes, and suspected COVID-19 symptoms among HCWs during lockdown.
We conducted an online survey of 5209 HCWs from 15 hospitals and health centers across Vietnam from April 6 to April 19, 2020. Participants answered questions related to sociodemographics, HL, eHEALS, adherence to IPC procedures, behavior changes in eating, smoking, drinking, and physical activity, and suspected COVID-19 symptoms. Principal component analysis, correlation analysis, and bivariate and multivariate linear and logistic regression models were used to validate the eHEALS and examine associations.
The eHEALS had a satisfactory construct validity with 8 items highly loaded on one component, with factor loadings ranked from 0.78 to 0.92 explaining 76.34% of variance; satisfactory criterion validity as correlated with HL (ρ=0.42); satisfactory convergent validity with high item-scale correlations (ρ=0.80-0.84); and high internal consistency (Cronbach α=.95). HL and eHEALS scores were significantly higher in men (unstandardized coefficient B=1.01, 95% CI 0.57-1.45, P<.001; B=0.72, 95% CI 0.43-1.00, P<.001), those with a better ability to pay for medication (B=1.65, 95% CI 1.25-2.05, P<.001; B=0.60, 95% CI 0.34-0.86, P<.001), doctors (B=1.29, 95% CI 0.73-1.84, P<.001; B 0.56, 95% CI 0.20-0.93, P=.003), and those with epidemic containment experience (B=1.96, 95% CI 1.56-2.37, P<.001; B=0.64, 95% CI 0.38-0.91, P<.001), as compared to their counterparts, respectively. HCWs with higher HL or eHEALS scores had better adherence to IPC procedures (B=0.13, 95% CI 0.10-0.15, P<.001; B=0.22, 95% CI 0.19-0.26, P<.001), had a higher likelihood of healthy eating (odds ratio OR 1.04, 95% CI 1.01-1.06, P=.001; OR 1.04, 95% CI 1.02-1.07, P=.002), were more physically active (OR 1.03, 95% CI 1.02-1.03, P<.001; OR 1.04, 95% CI 1.03-1.05, P<.001), and had a lower likelihood of suspected COVID-19 symptoms (OR 0.97, 95% CI 0.96-0.98, P<.001; OR 0.96, 95% CI 0.95-0.98, P<.001), respectively.
The eHEALS is a valid and reliable survey tool. Gender, ability to pay for medication, profession, and epidemic containment experience were independent predictors of HL and eHEALS scores. HCWs with higher HL or eHEALS scores had better adherence to IPC procedures, healthier lifestyles, and a lower likelihood of suspected COVID-19 symptoms. Efforts to improve HCWs' HL and eHEALS scores can help to contain the COVID-19 pandemic and minimize its consequences.
This paper describes elastic behavior and failure mechanisms of plain-knit fabric composites. A single-ply glass-fiber knit fabric impregnated with epoxy resin was used to fabricate composite ...specimens. Tensile tests were then carried out in two directions: the wale and the course directions of the fabric. During the test, the fracture behavior of the composite specimen was identified by a video camera which caught the loop images from the beginning to their failure. Tensile properties were also experimentally determined. Furthermore, a three-dimensional (3-D) finite element model of a knitted loop was proposed for prediction of tensile moduli as well as failure mechanisms of the plain-knit fabric composite. The validation of the loop model was estimated by comparison of the experimental results with the predicted ones.
A study was conducted on the effects of cooling conditions on flexural properties of aramid fiber knitted fabric (AFKF) and glass fiber knitted fabric (GFKF) reinforced thermoplastic polypropylene ...composites. To study these effects, composite laminates were fabricated under a molding pressure of 3MPa for 20min, then consolidated from the melt at different cooling conditions: rapid cooling i.e., quasi-quenching and gradual cooling. Flexural tests were carried out on specimens in two directions: wale and course. Evaluation on thermal properties and morphology was studied using a differential scanning calorimetry (DSC). Flexural properties were little sensitive to the cooling rates; however, gradually cooled specimens showed higher level of crystallinity than rapidly cooled specimens. Furthermore, flexural strengths displayed higher in the wale than in the course directions. SEM micrographs of fracture surfaces revealed poor adhesion between the fiber and polypropylene matrix.
A class of Cauchy problems for interesting complicated periodic pseudodifferential equations is considered. By the Galerkin-wavelet method and with weak solutions one can find sufficient conditions ...to establish convergence estimates of weak Galerkin-wavelet solutions to a Cauchy problem for this class of equations.
ObjectivesWe examined impacts and interactions of COVID-19 response involvement, health-related behaviours and health literacy (HL) on anxiety, depression, and health-related quality of life (HRQoL) ...among healthcare workers (HCWs).DesignA cross-sectional study was conducted. Data were collected 6 April to 19 April 2020 using online-based, self-administered questionnaires.Setting19 hospitals and health centres in Vietnam.Participants7 124 HCWs aged 21–60 years.ResultsThe COVID-19 response-involved HCWs had higher anxiety likelihood (OR (95% CI)=4.41 (3.53 to 5.51)), higher depression likelihood (OR(95% CI)=3.31 (2.71 to 4.05)) and lower HRQoL score (coefficient, b(95% CI)=−2.14 (−2.89 to −1.38)), compared with uninvolved HCWs. Overall, HCWs who smoked or drank at unchanged/increased levels had higher likelihood of anxiety, depression and lower HRQoL scores; those with unchanged/healthier eating, unchanged/more physical activity and higher HL scores had lower likelihood of anxiety, depression and higher HRQoL scores. In comparison to uninvolved HCWs who smoked or drank at never/stopped/reduced levels, involved HCWs with unchanged/increased smoking or drinking had lower anxiety likelihood (OR(95% CI)=0.34 (0.14 to 0.83)) or (OR(95% CI)=0.26 (0.11 to 0.60)), and lower depression likelihood (OR(95% CI)=0.33 (0.15 to 0.74)) or (OR(95% CI)=0.24 (0.11 to 0.53)), respectively. In comparison with uninvolved HCWs who exercised at never/stopped/reduced levels, or with those in the lowest HL quartile, involved HCWs with unchanged/increased exercise or with one-quartile HL increment reported lower anxiety likelihood (OR(95% CI)=0.50 (0.31 to 0.81)) or (OR(95% CI)=0.57 (0.45 to 0.71)), lower depression likelihood (OR(95% CI)=0.40 (0.27 to 0.61)) or (OR(95% CI)=0.63 (0.52 to 0.76)), and higher HRQoL scores (b(95% CI)=2.08 (0.58 to 3.58)), or (b(95% CI)=1.10 (0.42 to 1.78)), respectively.ConclusionsPhysical activity and higher HL were found to protect against anxiety and depression and were associated with higher HRQoL. Unexpectedly, smoking and drinking were also found to be coping behaviours. It is important to have strategic approaches that protect HCWs’ mental health and HRQoL.
PDF
