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We report our experience with an emergency room (ER) shutdown related to an accidental exposure to a patient with coronavirus disease 2019 (COVID-19) who had not been isolated.
A 635-bed, tertiary-care hospital in Daegu, South Korea.
To prevent nosocomial transmission of the disease, we subsequently isolated patients with suspected symptoms, relevant radiographic findings, or epidemiology. Severe acute respiratory coronavirus 2 (SARS-CoV-2) reverse-transcriptase polymerase chain reaction assays (RT-PCR) were performed for most patients requiring hospitalization. A universal mask policy and comprehensive use of personal protective equipment (PPE) were implemented. We analyzed effects of these interventions.
From the pre-shutdown period (February 10–25, 2020) to the post-shutdown period (February 28 to March 16, 2020), the mean hourly turnaround time decreased from 23:31 ±6:43 hours to 9:27 ±3:41 hours (P < .001). As a result, the proportion of the patients tested increased from 5.8% (N=1,037) to 64.6% (N=690) (P < .001) and the average number of tests per day increased from 3.8±4.3 to 24.7±5.0 (P < .001). All 23 patients with COVID-19 in the post-shutdown period were isolated in the ER without any problematic accidental exposure or nosocomial transmission. After the shutdown, several metrics increased. The median duration of stay in the ER among hospitalized patients increased from 4:30 hours (interquartile range [IQR], 2:17–9:48) to 14:33 hours (IQR, 6:55–24:50) (P < .001). Rates of intensive care unit admissions increased from 1.4% to 2.9% (P = .023), and mortality increased from 0.9% to 3.0% (P = .001).
Problematic accidental exposure and nosocomial transmission of COVID-19 can be successfully prevented through active isolation and surveillance policies and comprehensive PPE use despite longer ER stays and the presence of more severely ill patients during a severe COVID-19 outbreak.
Cultivated soybeans [Glycinemax (L.) Merr.] have various flower colours such as dark purple, purple, light purple, pink, magenta, near white and white. About one-third of the soybean accessions in the United States Department of Agriculture – Germplasm Resource Information Network (USDA-GRIN) Soybean Germplasm Collections have white flowers and are the second dominant accessions after the purple-flowered accessions. Earlier studies have shown that the w1 recessive allele of the W1 gene encoding flavonoid 3′,5′-hydroxylase produces white flowers. In the present study, we aimed to understand why the white-flowered accessions have become abundant among the cultivated soybeans and what their genetic and regional origin is. For this purpose, 99 landraces with white flowers and 39 landraces with purple flowers from eight Asian countries and Russia were analysed with regard to the nucleotide sequences of the W1 locus. We not only found that the w1 alleles of the 99 white-flowered landraces were identical to those of the white-flowered Williams 82, but also found that these w1 alleles displayed no polymorphism at all. By carrying out a phylogenetic analysis, we were able to identify a group with W1 alleles from which the w1 allele might have diverged.
Sesame (Sesamum indicum L.) is one of the oldest oil crops and is widely cultivated in Asia and Africa. The aim of this study was to assess the genetic diversity, phylogenetic relationships and population structure of 277 sesame core collection accessions collected from 15 countries in four different continents. A total of 158 alleles were detected among the sesame accessions, with the number varying from 3 to 25 alleles per locus and an average of 11.3. Polymorphism information content values ranged from 0.34 to 0.84, with an average of 0.568. These values indicated a high genetic diversity at 14 loci both among and within the populations. Of these, 44 genotype-specific alleles were identified in 12 of the 14 polymorphic simple sequence repeat markers. The core collection preserved a much higher level of genetic variation. Therefore, 10.1% was selected as the best sampling percentage from the whole collection when constructing the core collection. The 277 core collection accessions formed four robust clusters in the unweighted pair group method and the arithmetic averages (UPGMA) dendrogram, although the clustering did not indicate any clear division among the sesame accessions based on their geographical locations. Similar patterns were obtained using model-based structure analysis and country-based dendrograms, as some accessions situated geographically far apart were grouped together in the same cluster. The results of these analyses will increase our understanding of the genotype-specific alleles, genetic diversity and population structure of core collections, and the information can be used for the development of a future breeding strategy to improve sesame yield.
The “LEXT” confocal laser scanning microscope has been used for the three-dimensional (3D) imaging of the surface of specimens, especially in materials science fields, by the penetration of near-infrared (NIR) light without mechanical cutting, deposition, or other specimen pretreatment. Noninvasive investigation of various biological tissues such as human spinal dura mater, rat aorta, and cornea without the dehydration process was successfully carried out with the “LEXT,” in order to access both surface and internal topographic images of the biological structures at a good status of the wet tissue such as in vivo, especially in measuring tissue thickness. The confocal NIR laser microscopy offers the viable means to visualize tissue architecture and its thickness in microdomain to integrate 3D images efficiently. We believe that the “LEXT” has a good application for biological researchers to study biomaterials, and it would be useful as a diagnostic tool in the near future.
Nitrogen (N) and boron (B) codoped diamond-like carbon (DLC) films were prepared on silicon oxide substrates by RF magnetron sputtering to optimize the electrical conductivity and hardness of DLC film. The electrical conductivity and hardness of the N–B codoped DLC films were controlled simultaneously by varying N2 flow rate with fixed B target power and varying B target power with fixed N2flow rate. The electrical resistivity of the B-doped DLC films showed a cup-shaped relationship with B target power and a U-shaped relationship with the N–B codoped DLC film. However, hardness of the B-doped DLC films showed a decreasing behavior but it was maintained almost constant for the N–B codoped DLC film. These particular electrical and hardness behaviors of the N–B codoped DLC films could be explained by a neutralization effect of N and B codoping.
The sap of Acer mono has been called ‘bone-benefit-water’ in Korea because of its mineral and sugar content. In particular, the calcium concentration of the sap of A. mono is 37·5 times higher than commercial spring water. In the current study, we examined whether A. mono sap could improve or prevent osteoporosis-like symptoms in a mouse model. Male mice (3 weeks old) were fed a low-calcium diet supplemented with 25, 50 or 100 % A. mono sap, commercial spring water or a high calcium-containing solution as a beverage for 7 weeks. There were no differences in weekly weight gain and food intake among all the groups. Mice that were given a low-calcium diet supplemented with commercial spring water developed osteoporosis-like symptoms. To assess the effect of sap on osteoporosis-like symptoms, we examined serum calcium concentration, and femur density and length, and carried out a histological examination. Serum calcium levels were significantly lower in mice that received a low-calcium diet supplemented with commercial spring water (the negative control group), and in the 25 % sap group compared to mice fed a normal diet, but were normal in the 50 and 100 % sap and high-calcium solution groups. Femur density and length were significantly reduced in the negative control and 25 % sap groups. These results indicate that a 50 % sap solution can mitigate osteoporosis-like symptoms induced by a low-calcium diet. We also examined the regulation of expression of calcium-processing genes in the duodenum and kidney. Duodenal TRPV6 and renal calbindin-D9k were up-regulated dose-dependently by sap, and the levels of these factors were higher than those attained in the spring water-treated control. The results demonstrate that the sap of A. mono ameliorates the low bone density induced by a low-calcium diet, most likely by increasing calcium ion absorption.
The low frequency noise of individual ZnO nanowire (NW) field effect transistors (FETs) exposed to air is systematically characterized. The measured noise power spectrum shows a classical 1/f type. The noise amplitude is independent of source-drain current and inversely proportional to gate voltage. The extracted Hooge's constant of ZnO NW is found to be 6.52×10−3. In addition, the low frequency noise of ZnO NW according to NW resistance and contact property are investigated. The noise amplitude is proportional to the square of ZnO NW resistance. If a sample shows a nonlinear current-voltage (I-V) characteristic due to a poor electrical contact, the noise power spectrum is proportional to the third power of current instead of the square of current.
This paper presents analysis and experimental verifications of a new robot manipulator with five degrees of freedom developed for the buffing operation of shoes. First, the forward and inverse kinematics are analyzed. Next, an analytic closed-form solution is rigorously derived for the joint angles corresponding to the position and orientation of the end-effector in Cartesian coordinates. A control system, including input/output interfaces and the related electronic system, is designed for the control of the mechanical structure of the buffing robot. Then, peripheral systems integrated with the conveyer, transfer device, and fixture device are designed for the sequential buffing process of shoes. Also, a graphic user interface (GUI) program including the forward/inverse kinematics, control algorithm, and communication program to interact the robot with the peripheral systems is developed by using visual C++ language. A new flexible toolholder (FTH) is proposed to compensate for the excessive applied force between deburring tools and shoes. Finally, the test results are provided to demonstrate the effectiveness of the proposed scheme.
Field effect transistors(FETs) made of ZnO nanowires are very sensitive to the gas environment, so that the passivation can be a good way to get reliable nanowire FETs with longer lifetime and the better mobility. The studies on the passivation effects with the positive electron-beam resist was investigated by selectively covering the part of nanowire devices between the electrodes. Reproducible electrical characteristics were recorded, reflecting the stable electrical properties by the passivation which deters the degradation of a device. Considering the defect states of oxide nanowires dominate the charge states, the pre-state just before the passivation process will be crucial to understand the reproducible and controllable device characteristics of nanowire devices.
Using disaggregated panel data, we examine how firms change trade credit in response to a monetary tightening. We find that both accounts payable and accounts receivable increase with tighter monetary policy, implying that trade credit helps firms absorb the effect of a credit contraction. Further, both S&P 500 firms and a comparison group of smaller firms increase net trade credit (accounts receivable minus payable), making up for the reduced liquidity associated with tighter policy. However, we find no evidence that large firms play this role more actively than smaller firms.
Silicon carbide (SiC) microtubes were synthesized and characterized via a vapor–solid (VS) reaction of carbon fiber (Csolid) and SiO(gas). The synthesis mechanisms were investigated. The precursor led complete conversion of [SiO(gas) + C(solid)] into [SiC(solid) + CO(gas)] through overall reaction under inert gas flow at and above 1350 °C. Carbon fibers with small surface area (0.7–2.0 m2 g−1) were gradually converted to SiC microtubes with large specific surface area (45–63 m2 g−1). Inner surface of SiC microtubes indicated a villus-like morphology, which consisted of submicron-sized SiC villi. The outer surface of the SiC microtubes was smooth. Inner surface morphology of SiC microtubes was dependent upon synthesizing temperature. Thickness of villus-like layer in SiC microtubes increased with increasing synthesizing temperature, showing 0.25 and 0.5 at 1350 and 1400 °C, respectively. Both VS and gas–liquid–solid (VLS) growth mechanisms were investigated in synthesis of SiC fiber as a reaction byproduct, and the reaction was governed by both growth mechanisms.
Reducing interline capacitance and line resistance is required to minimize RC delays, reduce power consumption and crosstalk below 100nm node technology. For this purpose, various inorganic- and organic polymers have been tested to reduce dielectric constants in parallel with the use of copper as metal line. Lowering the dielectric constants, in particular, causes the detrimental effect on mechanical properties, and then leads to film damage and/or delamination during chemical-mechanical planarization CMP) or repeated thermal cure cycles. To overcome this issue, new carbon-bridged hybrid materials synthesized by organometallic silane precursors and sol-gel reaction are proposed.
In this work, we have developed new organic-inorganic hybrid low-k dielectrics with linear or cyclic carbon bridged structures. The differently bridged carbon structures were formed by a controlled reaction. 1H NMR, 29Si NMR analysis and GC/MSD analysis were conducted for the structural characterization of new hybrid low-k dielectric. The mechanical and dielectric properties of these hybrid materials were characterized by using nanoindentation with continuous stiffness measurement and Al dot MIS techniques. The results indicated that these organic-inorganic hybrid materials were very promising polymers for low-k dielectrics that had low dielectric constants with high thermal and mechanical properties. It has been also demonstrated that electrical and mechanical properties of the hybrid films could be tailored by copolymerization with PMSSQ and through the introduction of porogen.
A large rapakivi granite batholith in the Neo-Archaean/Palaeoproterozoic Odesan complex, northeastern Gyeonggi massif, South Korea, has been dated at 1839±10 Ma using SHRIMP U–Pb analysis of zircons. The age, petrological and geochemical characteristics of this batholith are similar to those of the rapakivi granite batholiths exposed in the Rangnim massif of North Korea and in the Miyun–Chengde complex of North China. The country rocks of these rapakivi granite batholiths are also comparable; all are composed of granitic gneisses and banded iron formation (BIF)-bearing supracrustal rocks metamorphosed to amphibolite- to granulite-facies. This study provides new evidence for the suggestion that the Gyeonggi and Rangnim massifs may share an affinity with the Precambrian basement of the North China craton. The study provides new insight into the possible eastward extension of the Sulu orogenic belt in the Korean peninsula and further provides evidence to correlate the Korea basement to a possible global 2.1–1.8 Ga supercontinent.
In the scribe lane, which is located at the frame neighboring two chips, most of the test patterns for monitoring electrical characteristics of memory device as well as various key patterns for photo process are formed. The pattern density of these regions is lower than that of the main chip area, and cause nitride erosion by dishing phenomena during HSS STI CMP process. Nitride erosion occurred in the scribe lane region, could the affect erosion properties of cell region in main chip area, results in within die remain nitride variation and marginal fail in device operation. In this work, in order to prevent these problems, pattern design in the scribe lane was modified so as not to occurs within die remain nitride variation. The effects of improvement in within die remain nitride variation were investigated by FIB-TEM analysis and its correlation with electrical properties were explained.
Dispersion characteristics of the surface modified MWNTs (Miltiwalled nanotubes) in the PU (polyurethane) matrix and electrical conductivity of the MWNTs/PU composites are investigated using SEM and DEA (Dielectric analyzer) with respect to the chemical treatment of MWNTs, the kind of surfactants and their content. Several chemical treatments of the MWNTs' surfaces were performed with the acids type, acidic concentration, treatment temperature, and oxidation time. All the surface of modified MWNTs are negatively charged and functionalized with carboxylic group; however, the external walls of some MWNTs were severely damaged so that they were frequently thinned and partially cracked. Compared to those of the composites without the addition of surfactant, the surfactant embedded into composites show much better dispersion of the MWNTs and higher electrical conductivity, these results are in good agreement with the two step adsorption model of cationic surfactants proposed by Y. Gao. Both the optimized MWNTs and cationic surfactant filled PU composites show very low percolation threshold, pc = 0.0089±0.007 vol. %, and relatively higher conductivity after percolation than other carbon nanotubes composite systems reported elsewhere.
Spin-on Low-K materials are potentially very attractive as interconnection
materials in a wide range of semiconductor structures. In this work, new
organic-inorganic hybrid materials synthesized by vinylsilane polymerization
were proposed. According to compositions and additional fabrications,
dielectric constants of these materials were evaluated to be 2.3∼3.1. The
hardness was 2.0GPa after 430°C curing. These materials had good adhesion
strength such that fracture toughness on silicon wafer was 0.22
MPam0.5 without any adhesion promoters. This result indicates
that these organicinorganic hybrid materials are very promising candidates
for low-K dielectrics.
We have analyzed Tb L3-edge x-ray absorption near-edge structure spectra of Tb-doped phosphor compounds for plasma display panel applications. Intensity and lifetime of the green emission from the Tb3+:5D4→7F5 transition were measured with respect to nominal terbium concentration in the host compounds, i.e., YBO3, YPO4,and Y4Al2O9, all of which were made through the solid-state reaction. Typical concentration quenching was evident on the fluorescence intensity and the fluorescing level lifetime in our samples. From the analyses of white line absorption peaks at TbL3-edge, it was verified that terbium is essentially trivalent in all the samples, even invery highly concentrated ones. Thus, this implies that the concentration quenching was not caused by presence of mixed-valent states of terbium. Instead, it is believed that anonradiative energy transfer route among Tb3+ ions might be responsible for thebehavior.
We have demonstrated that an efficient energy transfer takes place from Yb3+ to Cr4+ in calcium aluminate glasses. Yb3+ improves excitation efficiency at around 980 nm, enhancing emission intensity of Cr4+ fluorescence at 1.2–1.6 μm. Nonradiative energy transfer via electric dipole–dipole interaction between ytterbium and chromium ions was found to be dominant over radiative Yb3+ → Cr4+ energy transfer. A diffusionlimited energy transfer mechanism well explains the decay behavior of Yb3+/Cr4+- codoped glasses. This codoping scheme may be applicable to other Cr4+-containing crystals and glasses.