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The coronavirus disease 2019 (COVID-19) pandemic has led to significant strain on front-line healthcare workers.
In this multicentre study, we compared the psychological outcomes during the COVID-19 pandemic in various countries in the Asia-Pacific region and identified factors associated with adverse psychological outcomes.
From 29 April to 4 June 2020, the study recruited healthcare workers from major healthcare institutions in five countries in the Asia-Pacific region. A self-administrated survey that collected information on prior medical conditions, presence of symptoms, and scores on the Depression Anxiety Stress Scales and the Impact of Events Scale-Revised were used. The prevalence of depression, anxiety, stress and post-traumatic stress disorder (PTSD) relating to COVID-19 was compared, and multivariable logistic regression identified independent factors associated with adverse psychological outcomes within each country.
A total of 1146 participants from India, Indonesia, Singapore, Malaysia and Vietnam were studied. Despite having the lowest volume of cases, Vietnam displayed the highest prevalence of PTSD. In contrast, Singapore reported the highest case volume, but had a lower prevalence of depression and anxiety. In the multivariable analysis, we found that non-medically trained personnel, the presence of physical symptoms and presence of prior medical conditions were independent predictors across the participating countries.
This study highlights that the varied prevalence of psychological adversity among healthcare workers is independent of the burden of COVID-19 cases within each country. Early psychological interventions may be beneficial for the vulnerable groups of healthcare workers with presence of physical symptoms, prior medical conditions and those who are not medically trained.
Previous studies have suggested that probiotic fermented milk may possess blood pressure (BP)-lowering properties. In the present study, we aimed to systematically examine the effect of probiotic fermented milk on BP by conducting a meta-analysis of randomised controlled trials. PubMed, Cochrane library and the ClinicalTrials.gov databases were searched up to March 2012 to identify eligible studies. The reference lists of the obtained articles were also reviewed. Either a fixed-effects or a random-effects model was used to calculate the combined treatment effect. Meta-analysis of fourteen randomised placebo-controlled trials involving 702 participants showed that probiotic fermented milk, compared with placebo, produced a significant reduction of 3·10 mmHg (95 % CI − 4·64, − 1·56) in systolic BP and 1·09 mmHg (95 % CI − 2·11, − 0·06) in diastolic BP. Subgroup analyses suggested a slightly greater effect on systolic BP in hypertensive participants than in normotensive ones ( − 3·98 v. − 2·09 mmHg). Analysis of trials conducted in Japan showed a greater reduction than those conducted in European countries for both systolic BP ( − 6·12 v. − 2·08 mmHg) and diastolic BP ( − 3·45 v. − 0·52 mmHg). Some evidence of publication bias was present, but sensitivity analysis excluding small trials that reported extreme results only affected the pooled effect size minimally. In summary, the present meta-analysis suggested that probiotic fermented milk has BP-lowering effects in pre-hypertensive and hypertensive subjects.
With extremely disordered atomic structures, a glass possesses a thermal conductivity k that approaches the theoretical minimum of its composition, known as the Einstein’s limit.1 Depending on the material composition and the extent of disorder, the thermal conductivity of some glasses can be down to 0.1-0.3 W/m∙K at room temperature,2,3 representing some of the lowest k values among existing solids. Such a low k can be further reduced by the interfacial phonon scattering within a nanocomposite that can be used for thermal insulation applications. In this work, nanocomposites hot pressed from the mixture of glass nanopowder (GeSe4 or Ge20Te70Se10) and commercial SiO2 nanoparticles, or pure glass nanopowder, are investigated for the potential k reduction. It is found that adding SiO2 nanoparticles will instead increase k if the measured k values for usually porous nanocomposites are converted into those for the corresponding solid (kSolid) with Eucken’s formula. In contrast, pure glass nano-samples always show kSolid data significantly reduced from that for the starting glass. For a pure GeSe4 nano-sample, kSolid would beat the Einstein’s limit for its composition.
The spatially developing compressible plane mixing layer with a convective Mach number of 0.7 is investigated by direct numerical simulation. A pair of equal and opposite oblique instability waves is introduced to perturb the mixing layer at the inlet. The full evolution process of instability, including formation of -vortices and hairpin vortices, breakdown of large structures and establishment of self-similar turbulence, is presented clearly in the simulation. In the transition process, the flow fields are populated sequentially by -vortices, hairpin vortices and ‘flower’ structures. This is the first direct evidence showing the dominance of these structures in the spatially developing mixing layer. Hairpin vortices are found to play an important role in the breakdown of the flow. The legs of hairpin vortices first evolve into sheaths with intense vorticity then break up into small slender vortices. The later flower structures are produced by the instability of the heads of the hairpin vortices. They prevail for a long distance in the mixing layer until the flow starts to settle down into its self-similar state. The preponderance of slender inclined streamwise vortices is observed in the transversal middle zone of the transition region after the breakup of the hairpin legs. This predominance of streamwise vortices also persists in the self-similar turbulent region, though the vortices there are found to be relatively very weak. The evolution of both the mean streamwise velocity profile and the Reynolds stresses is found to have close connection to the behaviour of the large vortex structures. High growth rates of the momentum and vorticity thicknesses are observed in the transition region of the flow. The growth rates in the self-similar turbulence region decay to a value that agrees well with previous experimental and numerical studies. Shocklets occur in the simulation, and their formation mechanisms are elaborated and categorized. This is the first three-dimensional simulation that captures shocklets at this low convective Mach number.
A formulation of the boundary integral method for solving partial differential equations has been developed whereby the usual weakly singular integral and the Cauchy principal value integral can be removed analytically. The broad applicability of the approach is illustrated with a number of problems of practical interest to fluid and continuum mechanics including the solution of the Laplace equation for potential flow, the Helmholtz equation as well as the equations for Stokes flow and linear elasticity.
The I-V characteristics of AlGaN/GaN high electron mobility transistors in the temperature range between 100 K and 300 K are studied. It is found that both the maximum drain-source current and transconductance decrease with the increase of temperature. Decrease of the electron mobility with increasing temperature is considered to be the main cause for that condition. The threshold voltage shows a forward shift, which can be explained by the increase of Schottky barrier with increasing temperature. It is found that at VGS = 0 V the drain-source current reduces with the ascending temperature, which should be due to the variation of the electron mobility with the temperature. While at VGS = −5 V the drain-source current is found to increase with the ascending temperature, it is suggested to be caused by the positive temperature coefficient of the electron transport in the depleted region.
We have demonstrated and studied polymeric solid-state dye lasers (SSDLs) fabricated by three-dimensional (3D) polystyrene colloidal crystals and tert-butyl roadamine B (t-Bu RhB) doped Poly (methyl methacrylate) (PMMA) films with different film thickness. The sandwich-typed resonator cavities with different active layer thickness display single-mode lasing oscillations in the reflection bandgap of the colloidal crystals. The lasing thresholds could be optimized by changing the thickness of t-Bu RhB doped PMMA films, which is as low as 7.43 W/cm2. Adjusting active layer thickness would provide an opportunity to accelerate the development of fabricating polymeric SSDLs with low threshold.
Tensile-shear overload tests of spot welded cold-rolled 301LN plates deforming with slow and fast rates were carried out. The deformation behaviors of spot welds can be divided into two stages. Loading force with fast deformation rate increased more along with displacement in the first stage, while the force with slow rate increased more in the second stage. 21and 32(v.%) α´-martensite were introduced by failure deformation with fast and slow rates respectively. The hardness under the fracture surfaces was higher than HV400, which was more than two times of their original. The ultimate strengths and fracture energy absorptions of spot welds deforming with slow rate were higher than that with fast rate, especially for spot-welded thicker plates.
Studies of the wafer edge uniformity step by step, from hard mask deposition, reactive ion etch, electroplating to post Cu CMP had been done using scanning electron microscopy (SEM) measurements, showed that the major wafer non-uniformity comes from the Cu CMP step. Improvement of Cu CMP edge uniformity had been achieved through engineering of platen 1 using real time profile control as well as CMP head zone pressure adjustment and platen 3 slurry optimizations
Membrane separations are a key enabling technology for future energy conversion devices. Ionic transport membranes must have both proton and electronic conductivity to function as hydrogen separation membranes without an external power supply. A technical obstacle to material modification by compositional changes is that the hydrogen flux through a dense membrane is a function of both the proton ionic conductivity and the electronic conductivity. An alternative way to modify the materials conductivity without changing the ratio of the chemical constituents is by altering the microstructure. In this study, SrCe0.95Yb0.05O3 was produced by conventional mixed oxide bulk ceramic techniques and chemical solution routes self-rising approaches using urea as the leavening agent. In conventional ceramic processing routes, the perovskite phase was observed to form at temperatures near 1300oC, while solution techniques resulted in perovskite phase formation starting near 1000oC with complete phase transformations occurring at 1100oC. Thermogravimetric analysis (TGA) was conducted in various gas atmospheres resulting in bulk oxide route powders exhibiting a 0.6% weight loss at 800oC under a nitrogen environment as compared to chemically derived powders which displayed weight losses on the order of 3.4%.The increased weight loss observed in chemically derived SrCe0.95Yb0.05O3 is correlated with an increase in the number of electron charge carriers and results in elevated electronic conduction. This study will report on the development of structure property relations in the model proton conducting ceramic system SrCe0.95Yb0.05O3.
Endothelial hyperpermeability is a significant problem in vascular inflammation associated with trauma, ischaemia–reperfusion injury, sepsis, adult respiratory distress syndrome, diabetes, thrombosis and cancer. An important mechanism underlying this process is increased paracellular leakage of plasma fluid and protein. Inflammatory stimuli such as histamine, thrombin, vascular endothelial growth factor and activated neutrophils can cause dissociation of cell–cell junctions between endothelial cells as well as cytoskeleton contraction, leading to a widened intercellular space that facilitates transendothelial flux. Such structural changes initiate with agonist–receptor binding, followed by activation of intracellular signalling molecules including calcium, protein kinase C, tyrosine kinases, myosin light chain kinase, and small Rho-GTPases; these kinases and GTPases then phosphorylate or alter the conformation of different subcellular components that control cell–cell adhesion, resulting in paracellular hypermeability. Targeting key signalling molecules that mediate endothelial-junction–cytoskeleton dissociation demonstrates a therapeutic potential to improve vascular barrier function during inflammatory injury.
Bonding of pre-processed silicon wafers at back-end-of-the-line (BEOL) compatible conditions is one of the attractive approaches for three-dimensional (3D) integration. Among various technologies being evaluated, bonding of low temperature oxides (e.g., plasma-enhanced tetraethylorthosilicate (PETEOS)) is of great interest. In this work, we report low-temperature PETEOS-to-PETEOS wafer bonding, using a thin layer of titanium (Ti) as bonding intermediate. The bonding strength is evaluated qualitatively, while the bonding interface is examined by Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Preliminary results of PETEOS/Ti/PETEOS bonding on patterned wafers with single-level Cu damascene structures are also discussed.
To investigate the effects of partially substitution of lanthanum for bismuth in the BiScO3-PbTiO3 (BSPT) ceramics, the 0.38(Bi1−xLax)ScO3-0.62PbTiO3 (BLSPTx) ceramics were prepared by using conventional solid state process. It was found that the partial replacement of lanthanum for bismuth do not affects the crystalline structure of the BSPT ceramics. With increasing of the lanthanum content, the grains of BLSPTx ceramics grown much bigger than those of BSPT ceramics when BLSPTx and BSPT ceramics were sintered at the same temperature. The temperature dependence of dielectric permittivity of BLSPTx ceramics shows that the Curie temperature (Tc) shifts toward lower temperature with the increasing of lanthanum content, and the BLSPTx samples for x=0.02 show the highest value of the dielectric constant at Tc.
Pb(Sc1/2Ta1/2)O3 (PST) relaxor ferroelectric ceramics were investigated widely in the past decades for their excellent pyroelectric, ferroelectric and dielectric properties and comprehensive applications in uncooled focal plane arrays infrared detectors and other electronic devices. However, some other ferroelectrics could be added into the PST ceramics to form the complex perovskite ferroelectrics with better electric properties. In this paper, (1-x)PST-xPZT(PSTZT) relaxor ferroelectric ceramics were prepared by wolframite precursor process (named two-step -sintering method, TSSM). The experiment results showed that the PSTZT ceramics with pure perovskite structure could be prepared by using TSSM. The temperature dependence of permittivity and dielectric loss of PSTZT ceramics were investigated in detail, which indicated that PSTZT ceramics showed partly diffusive phase transition with little frequency dispersion. The dielectric and pyroelectric properties of PSTZT ceramics were also investigated and discussed.