Previous studies reported the positive viral RNA among coronavirus disease‐2019 (COVID‐19) recovered patients. This study aimed to summarize the current evidence of factors associated with the risk ...of disease recurrence. PubMed and Embase were searched until September 2020 to identify studies assessing characteristics of recurrence and nonrecurrence subjects after discharge. Random‐effect meta‐analysis was used to pool estimates of odds ratio (OR) or weighted mean difference (WMD) and their 95% confidence intervals (CIs) across studies. Meta‐analysis data were available for age, sex, hospital duration, disease severity, seven comorbidities, five symptoms, five indexes of blood routine, nine indexes of blood biochemistry, four treatment therapies, two antibodies, and history of high‐risk contact. Among them, hospital duration of recurrence cases was significantly shorter than nonrecurrence subjects (WMD, −1.55 days; 95% CI, −2.66 to −0.45). Fatigue, positive Immunoglobulin M (IgM), and positive IgG were associated with an increased risk of recurrence cases, with ORs and 95% CIs of 4.06 (1.14–14.4), 2.95 (1.15–7.61), and 3.45 (1.58–7.54), respectively. In contrast, the odds of recurrence cases were observed to significantly lower in subjects with elevated lactate dehydrogenase and C‐reactive protein, low lymphocyte count, steroid and arbidol use, with ORs (95% CIs) of 1.08 (0.27–4.37), 0.49 (0.27–0.97), 0.64 (0.42–0.97), 0.48 (0.25–0.96), and 0.48 (0.25–0.92), respectively. This study provided up‐to‐date evidence of several clinical and epidemiological characteristics in the association with COVID‐19 recurrence cases. Further in‐depth analyses for the causal effect of factors on re‐positive viral RNA are needed for the management of discharged patients with COVID‐19.
Highlights
Previous studies reported the positive viral RNA among COVID‐19 recovered patients.
In this study, we reported factors associated with COVID‐19 recurrence cases by performing a systematic review and meta‐analysis of current evidence.
Overall, factors including age, sex, hospital duration, disease severity, seven comorbidities, five symptoms, five indexes of blood routine, nine indexes of blood biochemistry, four treatment therapies, two antibodies, and history of high‐risk contact were examined in the final analysis.
Previous studies reported the recurrence of coronavirus disease 2019 (COVID-19) among discharge patients. This study aimed to examine the characteristic of COVID-19 recurrence cases by performing a ...systematic review and meta-analysis.
A systematic search was performed in PubMed and Embase and gray literature up to September 19, 2020. A random-effects model was applied to obtain the pooled prevalence of disease recurrence among recovered patients and the prevalence of subjects underlying comorbidity among recurrence cases. The other characteristics were calculated based on the summary data of individual studies.
A total of 41 studies were included in the final analysis, we have described the epidemiological characteristics of COVID-19 recurrence cases. Of 3,644 patients recovering from COVID-19 and being discharged, an estimate of 15% (95% CI, 12% to 19%) patients was re-positive with SARS-CoV-2 during the follow-up. This proportion was 14% (95% CI, 11% to 17%) for China and 31% (95% CI, 26% to 37%) for Korea. Among recurrence cases, it was estimated 39% (95% CI, 31% to 48%) subjects underlying at least one comorbidity. The estimates for times from disease onset to admission, from admission to discharge, and from discharge to RNA positive conversion were 4.8, 16.4, and 10.4 days, respectively.
This study summarized up-to-date evidence from case reports, case series, and observational studies for the characteristic of COVID-19 recurrence cases after discharge. It is recommended to pay attention to follow-up patients after discharge, even if they have been in discharge quarantine.
Phytonutrients exert several pharmacological effects on humans. In this study, we performed an umbrella review of the association of phytonutrient supplements (PNSs) with biomarkers of cardiovascular ...disease. Relevant published systematic reviews and meta‐analyses of clinical trials were identified by searching PubMed, Embase, and Cochrane Library until July 4, 2020. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) for summarized effects and I2 statistics of heterogeneity were extracted from individual studies or reanalyzed using a random‐effects model. Of the 50 included studies, pooled effects of PNSs on blood pressure, lipid profiles, and glycemic control were reported in 16, 25, and 14 articles, respectively. The findings appeared to be highly heterogeneous among individual trials of included systematic reviews and meta‐analyses. Ginger (WMD = −6.36 mmHg, 95% CI = −11.27, −1.46) and Hibiscus sabdariffa (WMD = −7.58 mmHg, 95% CI = −9.69, −5.46) were associated with lowered systolic blood pressure, whereas Aloe vera, Nigella sativa, and spirulina were associated with beneficial effects on both lipid profiles and glycemic control. In summary, this umbrella review has provided up‐to‐date evidence for the effect of PNSs on biomarkers related to hypertension, dyslipidemia, and diabetes. The results must be interpreted with caution due to potential heterogeneity.
The outbreak of novel pneumonia coronavirus disease has become a public health concern worldwide. Here, for the first time, the association between Korean meteorological factors and air pollutants ...and the COVID‐19 infection was investigated. Data of air pollutants, meteorological factors, and daily COVID‐19 confirmed cases of seven metropolitan cities and nine provinces were obtained from 3 February 2020 to 5 May 2020 during the first wave of pandemic across Korea. We applied the generalized additive model to investigate the temporal relationship. There was a significantly nonlinear association between daily temperature and COVID‐19 confirmed cases. Each 1°C increase in temperature was associated with 9% (lag 0‐14; OR = 1.09; 95% CI = 1.03‐1.15) increase of COVID‐19 confirmed cases when the temperature was below 8°C. A 0.01 ppm increase in NO2 (lag 0‐7, lag 0.14, and lag 0‐21) was significantly associated with increases of COVID‐19 confirmed cases, with ORs (95% CIs) of 1.13 (1.02‐1.25), 1.19 (1.09‐1.30), and 1.30 (1.19‐1.41), respectively. A 0.1 ppm increase in CO (lag 0‐21) was associated with the increase in COVID‐19 confirmed cases (OR = 1.10, 95% CI = 1.04‐1.16). There was a positive association between per 0.001 ppm of SO2 concentration (lag 0, lag 0‐7, and lag 0‐14) and COVID‐19 confirmed cases, with ORs (95% CIs) of 1.13 (1.04‐1.22), 1.20 (1.11‐1.31), and 1.15 (1.07‐1.25), respectively. There were significantly temporal associations between temperature, NO2, CO, and SO2 concentrations and daily COVID‐19 confirmed cases in Korea.
Highlights
‐ Data on air pollutants and meteorological factors from 16 cities and provinces in Korea were obtained.
‐ Temperature was associated with an increase of COVID‐19 confirmed cases when below 8oC.
‐ Positive associations between NO2, CO, and SO2 levels and COVID‐19 confirmed cases were observed.
The low hydration and carbonation of reactive MgO cement (RMC) under ambient conditions causes prolonged setting and low compressive strengths (~4 MPa). This study proposed a unique technique which ...led to the enhancement of the hydration and carbonation processes via the synergistic combination of microbial carbonation process (MCP) with a hydration agent (HA) that enabled the self‑carbonation of RMC-based mixes without using of any special curing environments. Through hydrolysing urea (CO(NH2)2) using ureolytic bacteria, CO32− ions were produced to facilitate the carbonation of dissolved Mg2+ ions to form hydrated magnesium hydroxy carbonates (HMHCs). The self‑carbonation of RMC enabled by the MCP resulted in formation of brucite with a poor crystallinity and its rapid conversion into HMHCs, which improved the setting time and compressive strength of RMC-based samples. The simultaneous use of MCP with 2 M urea and HA revealed HMHCs with improved morphologies, resulting in the highest compressive strength (~15 MPa).
The synergistic effect of food groups on health outcomes is better captured by examining dietary patterns (DPs) than single food groups. Regarding this issue, a Gaussian graphical model (GGM) can ...identify pairwise correlations between food groups and adjust for the remaining items. However, the application of GGMs in the nutritional field has not been widely investigated, especially in Korean adults.
The aim of this study was to identify the major DPs of Korean adults by using a GGM and to examine the associations between the DP scores and prevalence of self-reported cancer.
This cross-sectional study used baseline data from the 2007-2019 Cancer Screenee Cohort of the National Cancer Center, Korea.
In total, 10,777 Korean adults who completed a questionnaire regarding their general medical history, including clinical test results, and a validated food frequency questionnaire were included.
The main outcome measure was the prevalence of self-reported cancer at baseline.
DP networks were identified using a GGM. The GGM-identified networks were scored and categorized into tertiles, and their association with the prevalence of self-reported cancer was investigated using a multivariable logistic regression model.
The GGM identified the following 4 DP networks: principal, oil-sweet, meat, and fruit. After adjusting for covariates, the odds of moderate and high consumption of foods in the oil-sweet DP for participants who self-reported cancer were 25% and 34% lower than those for participants who did not report a cancer diagnosis (odds ratio OR = 0.75, 95% confidence interval CI = 0.62-0.90 and OR = 0.66, 95% CI = 0.53-0.81, respectively). Additionally, the odds of meat DP consumption in the self-reported cancer group was 29% lower than in participants who did not report a cancer diagnosis (OR = 0.71 and 95% CI = 0.57-0.88). In contrast, an increase in the odds of fruit DP consumption was observed for self-reported cancer participants (OR = 1.34 and 95% CI = 1.09-1.65). Similar results were observed among the female but not the male subjects.
GGM is a novel method that can distinguish the direct pairwise correlation of food groups and control for the indirect effect of other foods. Future large-scale longitudinal population-based studies are needed to build on these findings in general populations.
Surface acoustic wave spectroscopy has been established as non‐destructive and fast method for characterization of mechanical properties of surfaces and bulk materials in both research and industry. ...The present work shows that by application of a novel and robust aluminum nitride (AlN) coated piezoelectric contact sensor the advantages of the method can be extended from room temperature to at least 600°C. An overview of sensor concepts and applications of the method is discussed first, followed by theoretical and practical considerations for design and coating of a novel temperature stable contact sensor. After fabrication of such a sensor using magnetron sputtering, it was tested in a modified surface acoustic wave spectroscopy setup with an incorporated heating table concerning signal amplitude and frequency range. The AlN coated sensor was found to perform well up to 600°C, with temperature limited by the specification of the heating table. At room temperature, performance was acceptable when compared with a conventional contact sensor using a PVDF piezoelectric foil. Application of the high temperature capabilities of the setup was demonstrated by measuring temperature stability of hydrogen‐free amorphous carbon coatings (a‐C and ta‐C) depending on their sp3 carbon ratio. In another example, high precision temperature dependent measurement of Young's modulus for ultrasonic fatigue test specimen was taken, achieving an accuracy better than 1%. Use of the developed sensor opens up new possibilities in material science for in situ study of temperature depending mechanical properties for coatings and surfaces.
Buckling and postbuckling behaviors of sandwich plates reinforced by single-walled carbon nanotube (CNT), rested on elastic foundations and subjected to uniform temperature rise, are investigated in ...this article. CNT is embedded into matrix phase through uniform or functionally graded distributions. The properties of constituent materials are assumed to be temperature-dependent, and effective properties of nanocomposite are determined by extended rule of mixture. Two models of sandwich plates with face sheets and core layer reinforced by CNTs are presented. Formulations are based on the first-order shear deformation theory taking geometrical nonlinearity, initial geometrical imperfection, plate-foundation interaction, and elasticity of tangential edge constraints into consideration. Analytical solutions of deflection and stress function are assumed, and Galerkin method is applied to derive nonlinear temperature–deflection relation from which buckling temperatures and thermal postbuckling paths are obtained through an iteration algorithm. Numerical examples show the effects of CNT volume fraction, distribution patterns, in-plane edge constraint, elastic foundations, geometrical ratios, initial imperfection, and temperature dependence of properties on thermal postbuckling behavior of nanocomposite sandwich plates. The most important finding is that sandwich plate constructed from CNT-poor nanocomposite core layer and thin homogeneous face sheets with partially movable edges bring the best capacities of thermal buckling resistance and postbuckling load carrying.
This paper examines the bio-derived stabilization of sand-only or sand-plus-silt soils using an extracted bacterial enzyme application to achieve induced calcite precipitation (ICP). As compared to ...conventional microbial induced calcite precipitation (MICP) methods, which use intact bacterial cells, this strategy that uses free urease catalysts to secure bacterial enzyme–induced calcite precipitation (BEICP) appears to offer an improved means of bio-stabilizing silty-sand soils as compared to that of MICP processing. Several benefits may possibly be achieved with this BEICP approach, including bio-safety, environmental, and geotechnical improvements. Notably, the BEICP bio-stabilization results presented in this paper demonstrate (i) higher rates of catalytic urease activity, (ii) a wider range of application with sand-plus-silt soil applications bearing low-plasticity properties, and (iii) the ability to retain higher levels of soil permeability after BEICP processing. Comparative BEICP versus MICP results for sand-only systems are presented, along with BEICP-based results for stabilized soil mixtures at 90:10 and 80:20 percentile sand:silt ratios. This BEICP method’s ability to obtain unconfined compressive strength results in excess of 1000 kPa with sand-plus-silt soil mixtures is particularly noteworthy.
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