Abstract
Background
Recent studies have focused on initial clinical and epidemiological characteristics of the coronavirus disease 2019 (COVID-19), which is the mainly revealing situation in Wuhan, ...Hubei.
Aim
This study aims to reveal more data on the epidemiological and clinical characteristics of COVID-19 patients outside of Wuhan, Zhejiang, China.
Design
This study was a retrospective case series.
Methods
Eighty-eight cases of laboratory-confirmed and three cases of clinically confirmed COVID-19 were admitted to five hospitals in Zhejiang province, China. Data were collected from 20 January 2020 to 11 February 2020.
Results and discussion
Of all 91 patients, 88 (96.70%) were laboratory-confirmed COVID-19 with throat swab samples that tested positive for SARS-Cov-2, three (3.30%) cases were clinically diagnosed. The median age of the patients was 50 (36.5–57) years, and female accounted for 59.34%. In this sample, 40 (43.96%) patients had contracted the disease from local cases, 31 (34.07%) patients had been to Wuhan/Hubei, eight (8.79%) patients had contacted with people from Wuhan, and 11 (12.09%) patients were diagnosed after having flown together in the same flight with no passenger that could later be identified as the source of infection. In particular within the city of Ningbo, 60.52% cases can be traced back to an event held in a temple. The most common symptoms were fever (71.43%), cough (60.44%) and fatigue (43.96%). The median of incubation period was 6 (interquartile range 3–8) days and the median time from the first visit to a doctor to the confirmed diagnosis was 1 (1–2) days. According to the chest computed tomography scans, 67.03% cases had bilateral pneumonia.
Conclusions
Social activity cluster, family cluster and flying alongside with persons already infected with COVID-19 were how people got infected with COVID-19 in Zhejiang.
The development of new or more sustainable, active, efficient, controlled, and selective polymerization reactions or processes continues to be crucial for the synthesis of important polymers or ...materials with specific structures or functions. In this context, the newly emerged polymerization technique enabled by main-group Lewis pairs (LPs), termed as Lewis pair polymerization (LPP), exploits the synergy and cooperativity between the Lewis acid (LA) and Lewis base (LB) sites of LPs, which can be employed as frustrated Lewis pairs (FLPs), interacting LPs (ILPs), or classical Lewis adducts (CLAs), to effect cooperative monomer activation as well as chain initiation, propagation, termination, and transfer events. Through balancing the Lewis acidity, Lewis basicity, and steric effects of LPs, LPP has shown several unique advantages or intriguing opportunities compared to other polymerization techniques and demonstrated its broad polar monomer scope, high activity, control or livingness, and complete chemo- or regioselectivity, as well as its unique application in materials chemistry. These advances made in LPP are comprehensively reviewed, with the scope of monomers focusing on heteroatom-containing polar monomers, while the polymerizations mediated by main-group LAs and LBs separately that are most relevant to the LPP are also highlighted or updated. Examples of applying the principles of the LPP and LP chemistry as a new platform for advancing materials chemistry are highlighted, and currently unmet challenges in the field of the LPP, and thus the suggested corresponding future research directions, are also presented.
The hot deformation behaviors of 6082 aluminum alloys containing different Mn contents (0.05–1.0 wt%) were systematically investigated by uniaxial compression tests in a temperature range of ...400–550 °C and strain rate range of 0.001–1 s-1. Prior to the hot deformation, a low-temperature homogenization (450 °C for 6 h) was carried out on direct-chill cast billets to promote the precipitation of Mn-containing dispersoids. The large numbers of dispersoids in the Mn-containing alloys yielded significantly increased high-temperature flow stresses, compared to that of the base alloy without dispersoids. The material constants and activation energies for hot deformation were determined using the hyperbolic-sine constitutive equation and experimental peak flow stress data. The activation energy increased from 191 kJ/mol for the base alloy to 286 kJ/mol for the alloy with 0.5% of Mn. With further increase in Mn content, the activation energy increased only moderately to 315 kJ/mol for the alloy with 1.0% of Mn. The influences of the Mn content and deformation conditions on the dynamic recovery and recrystallization were quantitatively analyzed. The precipitation of dispersoids in the Mn-containing alloys promoted the retardation of the dynamic recovery and inhibition of the recrystallization owing to their strong pinning effect on the dislocation movement and subgrain migration.
To explore the characteristics of Helicobacter pylori resistance in China and the association between antibiotic resistance and several clinical factors.
H. pylori strains were collected from ...patients in 13 provinces or cities in China between 2010 and 2016. Demographic data including type of disease, geographic area, age, gender and isolation year were collected to analyse their association with antibiotic resistance. Antibiotic resistance was detected using the Etest test and the Kirby-Bauer disc diffusion method.
H. pylori were successfully cultured from 1117 patients. The prevalence of metronidazole, clarithromycin (CLA), azithromycin, levofloxacin (LEV), moxifloxacin, amoxicillin (AMO), tetracycline and rifampicin resistance was 78.2, 22.1, 23.3, 19.2, 17.2, 3.4, 1.9 and 1.5%, respectively. No resistance to furazolidone was observed. The resistance rates to LEV and moxifloxacin were higher in strains isolated from patients with gastritis compared to those with duodenal ulcer and among women. Compared to patients ≥40 years old, younger patients exhibited lower resistance rates to CLA, azithromycin, LEV and moxifloxacin. The resistance rates to CLA and AMO were higher in strains isolated more recently, and we also found that the prevalence of resistance to metronidazole, CLA, azithromycin and AMO were significantly different among different regions of China.
The resistance rates to metronidazole, CLA and LEV were high in China. Patient age, gender, disease and location were associated with the resistance of H. pylori to some antibiotics. Furazolidone, AMO and tetracycline are better choices for H. pylori treatment in China.
The structure and reorientational dynamics of KB3H8 were studied by using quasielastic and inelastic neutron scattering, Raman spectroscopy, first-principles calculations, differential scanning ...calorimetry, and in situ synchrotron radiation powder X-ray diffraction. The results reveal the existence of a previously unknown polymorph in between the α′- and β-polymorphs. Furthermore, it was found that the B3H8− anion undergoes different reorientational motions in the three polymorphs α, α′, and β. In α-KB3H8, the B3H8− anion performs 3-fold rotations in the plane created by the three boron atoms, which changes to a 2-fold rotation around the C 2 symmetry axis of the B3H8− anion upon transitioning to α′-KB3H8. After transitioning to β-KB3H8, the B3H8− anion performs 4-fold rotations in the plane created by the three boron atoms, which indicates that the local structure of β-KB3H8 deviates from the global cubic NaCl-type structure. The results also indicate that the high reorientational mobility of the B3H8− anion facilitates the K+ cation conductivity, since the 2-orders-of-magnitude increase in the anion reorientational mobility observed between 297 and 311 K coincides with a large increase in K+ conductivity.
The first effective organopolymerization of the biorenewable “non‐polymerizable” γ‐butyrolactone (γ‐BL) to a high‐molecular‐weight metal‐free recyclable polyester is reported. The superbase ...tert‐Bu‐P4 is found to directly initiate this polymerization through deprotonation of γ‐BL to generate reactive enolate species. When combined with a suitable alcohol, the tert‐Bu‐P4‐based system rapidly converts γ‐BL into polyesters with high monomer conversions (up to 90 %), high molecular weights (Mn up to 26.7 kg mol−1), and complete recyclability (quantitative γ‐BL recovery).
Recyclable and renewable: The fast organopolymerization of the biorenewable non‐strained γ‐butyrolactone has led to a high‐molecular‐weight metal‐free polyester with complete recyclability. The monomer has been long believed to be a non‐polymerizable monomer because of its stable five‐membered ring structure.
•Sputtering-derived Hf1−xTixO2 gate dielectrics have been deposited on Si substrates.•Increase in crystallization temperature and reduction in Eg have been observed.•Formation of silicate layer for ...9% TiO2-doped HfO2/Si sample has been detected.
TiO2-doped HfO2 gate dielectric thin films have been deposited on Si(100) substrates by RF sputtering. The component, morphology, structure, optical and interfacial properties of Hf1−xTixO2 films related to TiO2 concentration are systematically investigated by atomic force microscope (AFM), X-ray diffraction (XRD), spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier transformation infrared (FTIR). By employing Cauchy–Urbach model, the optical constants, such as refractive index (n), extinction coefficient (k), absorption coefficient (α), and optical band gap (Eg) have been determined precisely. Measurements from XRD have confirmed that TiO2 incorporating into HfO2 films leads to the increase of the crystallization temperature of HfO2 films with increasing the TiO2 concentration. SE analyses have indicated that reduction in band gap and refractive index has been observed with increasing the TiO2 component in Hf1−xTixO2 films. The increase in Urbach parameter EU with the increase of TiO2 concentration also suggests the rise in disorder for Hf1−xTixO2 films. FTIR measurements for Hf1−xTixO2/Si gate stack indicate the existence of the interfacial layer regardless of the TiO2 concentration. For the 9% TiO2-doped HfO2 samples, the shift in FTIR characteristic peak suggests the formation of the silicate layer, which leads to the suppressed interfacial layer growth during deposition. As a result, it can be conclude that the TiO2 component in Hf1−xTixO2 films should be controlled precisely to guarantee interfacial properties of Hf1−xTixO2/Si gate stacks.
Minimally important difference (MID) refers to the smallest meaningful difference that carries implications for patient care. Minimally important differences are necessary to help interpret ...patient-reported pain outcomes in research and clinical practice. The PROMIS pain interference scales were validated across diverse samples; however, more information about their MIDs could improve their interpretability. The purpose of this study was to estimate MIDs for 4 fixed-length PROMIS pain interference scales, including the 6-item Pain Short Form and the 4-, 6-, and 8-item pain interference scales used in the PROMIS profile instruments. Data were analyzed from 3 randomized controlled trials (N = 759). The 3 samples, respectively, consisted of patients with chronic low back pain (n = 261), chronic back pain or hip/knee osteoarthritis pain (n = 240), and a history of stroke (n = 258). For each sample, anchor- and distribution-based approaches were used to estimate MIDs. Standard error of measurement and effect sizes were used as distribution-based MID estimates. Anchor-based MID estimates were established by mapping PROMIS pain interference scores onto established anchor measures, including the Brief Pain Inventory, and retrospective and prospective global ratings of change. The distribution- and anchor-based MID estimates showed convergence. For the pain samples, MID estimates ranged from 2 to 3 T-score points. For the nonpain sample, MID estimates ranged from 3.5 to 4.5 T-score points. The MID estimates were comparable across the 4 fixed-length scales. These MIDs can be used to evaluate treatment effects in research and clinical care and to calculate estimates for powering clinical trials.
The development of chemically recyclable polymers promises a closed‐loop approach towards a circular plastic economy but still faces challenges in structure/property diversity and depolymerization ...selectivity. Here we report the first successful coordination ring‐opening polymerization of 4,5‐trans‐cyclohexyl‐fused γ‐butyrolactone (M1) with lanthanide catalysts at room temperature, producing P(M1) with Mn up to 89 kg mol−1, high thermal stability, and a linear or cyclic topology. The same catalyst also catalyses selective depolymerization of P(M1) back to M1 exclusively at 120 °C. This coordination polymerization is also living, enabling the synthesis of well‐defined block copolymer.
Living and reborn: Metal‐mediated coordination polymerization of a trans‐fused six‐five bicyclic lactone is living or catalytic, creating linear or cyclic polymers with high thermal stability and complete chemical recyclability.
The hot deformation behaviors of Al–Mg–Mn 5xxx alloys with different Mn contents (0.1–1 wt.%) were studied by carrying out uniaxial compression tests over the temperature and strain rate ranges of ...350–500 °C and 0.001–1.0 s−1, respectively. In the pre-deformed state, Mn dispersoids appeared in the α-Al matrix once the Mn content reached 0.4%. The density of these dispersoids increased with a further increase in the Mn content. The peak flow stress gradually increased with an increase in the Mn content under a given deformation condition owing to the strong strengthening effect of the dispersoids, and the activation energy of hot deformation also increased with increasing Mn content. The deformed microstructures were analyzed using the electron backscatter diffraction technique, and the dominant restoration mechanisms were classified based on the Zener-Hollomon parameter (Z). Under low-Z deformation conditions, continuous dynamic recrystallization (CDRX) was the principal softening mechanism. At intermediate Z values, CDRX was partially accompanied by particle-stimulated and discontinuous DRX. At higher Z values, dynamic recovery was the only softening mechanism, which was mainly dominated by work hardening.
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