60 research outputs found

    Distribution of bacterial keratitis and emerging resistance to antibiotics in China from 2001 to 2004

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    Chen Zhang, Yanchuang Liang, Shijing Deng, Zhiqun Wang, Ran Li, Xuguang SunDepartment of Ocular Microbiology, Beijing Institute of Ophthalmology, Beijing Tongren hospital, Capital University of Medical Science, BeijingObjective: To study on the distribution of bacterial keratitis isolates and the resistance to antibiotics in China from 2001 to 2004.Methods: 1985 specimens from the bacterial keratitis at the Beijing Tong Ren Eye Center were cultured and identified. In vitro susceptibility testing of positive isolates to antibiotics was determined by the Kirby-Bauer disk diffusion method and interpreted according to Clinical and Laboratory Standards Institute.Results: Out of 1985 specimens, 279 were culture positive. The percentage of positive culture was 14.06%. Gram-positive cocci and gram-negative bacilli represented 42.65% (119/270) and 35.13% (98/279) respectively. Pseudomonas sp. was the most common organism (20.07%), followed by Corynebacterium sp. (16.85%) and Staphylococcus epidermidis (13.98%). Resistance to ofloxacin, ciprofloxacin, levofloxacin, and tobramycin was 20.2%, 35.9%, 15.5%, and 29.4% respectively. Gram-negative bacilli showed higher resistance to ciprofloxacin. Staphycoccus sp. revealed significant resistance to ciprofloxacin. Streptococcus sp. showed high resistance to tobramycin. The resistance of isolates from older patients (≥60Y) to ciproloxacin, levofloxacin, and tobramycin was higher than that from adult patients (>14 to 59Y).Conclusion: Staphylococcus sp., Pseudomonas sp., and Corynebacterium sp. were the most common bacterial keratitis isolates in China. Attentions should be paid to the increase of the resistance to levofloxacin.Keywords: bacteria keratitis resistanc

    Global assessment of spatiotemporal changes of frequency of terrestrial wind speed

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    Wind energy, an important component of clean energy, is highly dictated by the disposable wind speed within the working regime of wind turbines (typically between 3 and 25 m s−1 at the hub height). Following a continuous reduction ('stilling') of global annual mean surface wind speed (SWS) since the 1960s, recently, researchers have reported a 'reversal' since 2011. However, little attention has been paid to the evolution of the effective wind speed for wind turbines. Since wind speed at hub height increases with SWS through power law, we focus on the wind speed frequency variations at various ranges of SWS through hourly in-situ observations and quantify their contributions to the average SWS changes over 1981–2021. We found that during the stilling period (here 1981–2010), the strong SWS (⩾ 5.0 m s−1, the 80th of global SWS) with decreasing frequency contributed 220.37% to the continuous weakening of mean SWS. During the reversal period of SWS (here 2011–2021), slight wind (0 m s−1 < SWS < 2.9 m s−1) contributed 64.07% to a strengthening of SWS. The strengthened strong wind (⩾ 5.0 m s−1) contributed 73.38% to the trend change of SWS from decrease to increase in 2010. Based on the synthetic capacity factor series calculated by considering commercial wind turbines (General Electric GE 2.5-120 model with rated power 2.5 MW) at the locations of the meteorological stations, the frequency changes resulted in a reduction of wind power energy (−10.02 TWh yr−1, p < 0.001) from 1981 to 2010 and relatively weak recovery (2.67 TWh yr−1, p < 0.05) during 2011–2021.This study was supported by the National Natural Science Foundation of China (Grant No. 42071022), Guangdong Basic and Applied Basic Research Fund (2022A1515240070) and the start-up fund provided by Southern University of Science and Technology (no. 29/Y01296122). C A-M was supported by the IBER-STILLING (RTI2018-095749-A-I00, MCIU/AEI/FEDER,UE); VENTS (GVA-AICO/2021/023); the CSIC Interdisciplinary Thematic Platform (PTI) Clima (PTI-CLIMA); and the 2021 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation. RJHD was supported by the Met Office Hadley Centre Climate Programme funded by BEIS and by the UK-China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund. SJ was supported by the Ramon y Cajal program and the OPEN project (RYC2020-029993-I and TED2021-131074B-I00, MCIU/AEI/FEDER,UE)

    TGF-ß Sma/Mab Signaling Mutations Uncouple Reproductive Aging from Somatic Aging

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    Female reproductive cessation is one of the earliest age-related declines humans experience, occurring in mid-adulthood. Similarly, Caenorhabditis elegans' reproductive span is short relative to its total life span, with reproduction ceasing about a third into its 15–20 day adulthood. All of the known mutations and treatments that extend C. elegans' reproductive period also regulate longevity, suggesting that reproductive span is normally linked to life span. C. elegans has two canonical TGF-ß signaling pathways. We recently found that the TGF-ß Dauer pathway regulates longevity through the Insulin/IGF-1 Signaling (IIS) pathway; here we show that this pathway has a moderate effect on reproductive span. By contrast, TGF-ß Sma/Mab signaling mutants exhibit a substantially extended reproductive period, more than doubling reproductive span in some cases. Sma/Mab mutations extend reproductive span disproportionately to life span and act independently of known regulators of somatic aging, such as Insulin/IGF-1 Signaling and Dietary Restriction. This is the first discovery of a pathway that regulates reproductive span independently of longevity and the first identification of the TGF-ß Sma/Mab pathway as a regulator of reproductive aging. Our results suggest that longevity and reproductive span regulation can be uncoupled, although they appear to normally be linked through regulatory pathways

    Constructing a MoS2 QDs/CdS Core/Shell Flowerlike Nanosphere Hierarchical Heterostructure for the Enhanced Stability and Photocatalytic Activity

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    MoS2 quantum dots (QDs)/CdS core/shell nanospheres with a hierarchical heterostructure have been prepared by a simple microwave hydrothermal method. The as-prepared samples are characterized by XRD, TEM, SEM, UV-VIS diffuse reflectance spectra (DRS) and N2-sorption in detail. The photocatalytic activities of the samples are evaluated by water splitting into hydrogen. Results show that the as-prepared MoS2 QDs/CdS core/shell nanospheres with a diameter of about 300 nm are composed of the shell of CdS nanorods and the core of MoS2 QDs. For the photocatalytic reaction, the samples exhibit a high stability of the photocatalytic activity and a much higher hydrogen evolution rate than the pure CdS, the composite prepared by a physical mixture, and the Pt-loaded CdS sample. In addition, the stability of CdS has also been greatly enhanced. The effect of the reaction time on the formations of nanospheres, the photoelectric properties and the photocatalytic activities of the samples has been investigated. Finally, a possible photocatalytic reaction process has also been proposed

    Numerical Modeling and Experimental Verification for High-Speed and Heavy-Load Planar Mechanism with Multiple Clearances

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    Transmission mechanism is one of the most important parts of the Ultra-High Voltage (UHV) circuit breaker. It has specific characteristics such as fast response, high speed, and heavy load in the processes of open and close actions. This paper studies the effects of multiple clearances on the working characteristics of transmission mechanism system, especially the motion of its journal center path during operation. It builds a nonlinear kinetic model of transmission mechanism considering the system energy losses due to the impact and friction between the journal and bearing inside clearance joints. Also, an experimental platform is built to measure the displacement and velocity of the moving contact. The results show that the existence of 15 clearance joints in our mechanism system can cause hysteresis effects on the velocity and acceleration of the moving contact, as well as its acceleration fluctuation. Meanwhile, the increase of friction coefficient will stabilize the dynamic characteristic. In addition, both the experimental and simulation results indicate that the motion of the journal center, which is unevenly distributed along the circle, is characterized by three phases: free flight motion, contact motion, and impact motion

    Modeling and Analysis on Cushion Characteristics of Fast and High-Flow-Rate Hydraulic Cylinder

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    As an indispensable actuator, the hydraulic cylinder has widespread industrial applications in mechanical engineering. The cushion characteristics of hydraulic cylinder directly affect its performance and reliability, especially the one utilized in hydraulic system with fast response, high flow rate, and instantaneous super power. In order to analyze the cushion characteristics, three different simulation models are established. Furthermore, experiments concerning the pressure characteristics of hydraulic cylinder are accomplished to verify the validation of simulation models. It was found that the integrated simulation model had the highest precision and CFD model showed better pattern of cushion process compared with other models. On the basis of the integrated simulation model, plunger structure and key structural parameters were studied in detail with optimal schemes given. The conical structure, proper design of the diameter of cushion hole, and length of plunger turned out to be effective in promoting the cushion performance. The proposed simulation models and research of cushion structure have scientific and engineering value to promote the innovative development of hydraulic cylinder

    Table2_Gastroesophageal reflux disease and oral symptoms: A two-sample Mendelian randomization study.XLSX

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    Background: The association between Gastroesophageal reflux disease (GERD) and oral symptoms has been reported in observational studies, but the causality of GERD to oral symptoms remained unknown. We aimed to assess the causal effect of GERD on five oral symptoms (mouth ulcers, toothache, loose teeth, bleeding gums, and periodontitis) using the two-sample Mendelian randomization (MR) method.Methods: Summary-level statistics for GERD and five oral symptoms were obtained from large-scale genome-wide association studies. Rigorous quality control of genetic instruments was conducted before MR analysis. Several analytical methods, including the inverse-variance weighted (IVW) method, MR-Egger regression, weighted median, maximum likelihood, and robust adjusted profile score (RAPS) were utilized, and the results of IVW were taken as the main results. The MR-Egger intercept test, Cochran’s Q test, and leave-one-out test were used as sensitivity analysis for quality control.Results: After Bonferroni, IVW detected a significant effect of GERD on mouth ulcers (OR = 1.008, 95% CI = 1.003–1.013, p = 0.003), loose teeth (OR = 1.009, 95% CI = 1.005–1.012, p = 9.20 × 10−7), and periodontitis (OR = 1.229, 95% CI = 1.081–1.398, p = 0.002). Consistent patterns of associations were observed across several MR models and sensitivity analysis found little evidence of bias. Nominal significant associations were observed in toothache and bleeding gums (p Conclusion: Our MR analyses supported the positive causal effect of GERD on oral symptoms, especially for mouth ulcers, loose teeth, and periodontitis. Our findings might shed light on the mechanism of oral disease and might imply that oral care should be enhanced in patients with GERD.</p

    Table1_Gastroesophageal reflux disease and oral symptoms: A two-sample Mendelian randomization study.DOCX

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    Background: The association between Gastroesophageal reflux disease (GERD) and oral symptoms has been reported in observational studies, but the causality of GERD to oral symptoms remained unknown. We aimed to assess the causal effect of GERD on five oral symptoms (mouth ulcers, toothache, loose teeth, bleeding gums, and periodontitis) using the two-sample Mendelian randomization (MR) method.Methods: Summary-level statistics for GERD and five oral symptoms were obtained from large-scale genome-wide association studies. Rigorous quality control of genetic instruments was conducted before MR analysis. Several analytical methods, including the inverse-variance weighted (IVW) method, MR-Egger regression, weighted median, maximum likelihood, and robust adjusted profile score (RAPS) were utilized, and the results of IVW were taken as the main results. The MR-Egger intercept test, Cochran’s Q test, and leave-one-out test were used as sensitivity analysis for quality control.Results: After Bonferroni, IVW detected a significant effect of GERD on mouth ulcers (OR = 1.008, 95% CI = 1.003–1.013, p = 0.003), loose teeth (OR = 1.009, 95% CI = 1.005–1.012, p = 9.20 × 10−7), and periodontitis (OR = 1.229, 95% CI = 1.081–1.398, p = 0.002). Consistent patterns of associations were observed across several MR models and sensitivity analysis found little evidence of bias. Nominal significant associations were observed in toothache and bleeding gums (p Conclusion: Our MR analyses supported the positive causal effect of GERD on oral symptoms, especially for mouth ulcers, loose teeth, and periodontitis. Our findings might shed light on the mechanism of oral disease and might imply that oral care should be enhanced in patients with GERD.</p

    Design and Synthesis of TiO2 Hollow Spheres with Spatially Separated Dual Cocatalysts for Efficient Photocatalytic Hydrogen Production

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    TiO2 hollow spheres modified with spatially separated Ag species and RuO2 cocatalysts have been prepared via an alkoxide hydrolysis–precipitation method and a facile impregnation method. High-resolution transmission electron microscopy studies indicate that Ag species and RuO2 co-located on the inner and outer surface of TiO2 hollow spheres, respectively. The resultant catalysts show significantly enhanced activity in photocatalytic hydrogen production under simulated sunlight attributed to spatially separated Ag species and RuO2 cocatalysts on TiO2 hollow spheres, which results in the efficient separation and transportation of photogenerated charge carriers
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