Search

• Three 1.6 m (Length) × 1.6 m (Width) diesel oil pool fire tests were carried out on two URTS in hot summer. • Shafts exhausted out of much smoke, but backflow occurred farther away from the fire sources. • Temperatures/velocities under the ceiling decayed longitudinally with the power index law. • The measured mass flow rates out of unit shafts were in range of 0.31 ∼ 1.76 kg/s.m2. • Dimensionless number Ri′ was adopted to assess the smoke flow under the shafts. Shallow-buried urban road tunnels with shafts (URTS) have been operated in large cities of China, and successfully released the traffic congestion. Fire smoke is expected to exhaust out of one-side shaft groups driven by its own thermal buoyancy. However, full-scale test data of the fire smoke spreading in such tunnel are still lacked, and the prediction models needs to be verified. In hot summer of year 2020, three full-scale experiments were carried out on two URTS. A 1.6 m (length) × 1.6 m (width) iron pan was placed on ground with diesel oil used as the fire source. Testing systems were arranged under the ceiling, on top openings of shafts and at bottoms of shafts. Lots of smoke were rapidly exhausted out of the shafts closer to the fire sources, but backflow occurred at bottoms of those shafts farther from the fire sources being not conducive to smoke extraction. Other three results of full-scale fire experiments conducted on one URTS in cold winter are provided here for comparison. The findings are that both the ceiling smoke temperatures and the smoke spreading velocities decayed longitudinally well with the exponential function, and the downstream temperature attenuation coefficient k 2 were in range of 0.042 ∼ 0.188 being smaller than that of the upstream, also the hotter the weather, the smaller the k 2 ; maximum values on top openings of the shafts were measured to be 47 °C in temperature, 5 m/s in velocity and 180 ppm in CO concentration; mass flow rates of the unit shafts were measured to decrease away from the fire sources that were 0.30 ∼ 1.77 kg/(s·m2) in Fires 1 and 2, and 0.46 ∼ 1.27 kg/(s·m2) in Fire 3, also the prediction models were confirmed not to be accurate enough; number R i ′ differed among all unit shafts of Shaft 6#, and were about 13.5 ∼ 15.2 in Fire 1, but smaller to be about 1.4 in Fire 2. [ABSTRACT FROM AUTHOR]

The unprecedented expansion and development of high-speed rail (HSR) in China provides a unique opportunity and a new way of thinking for addressing the problem of urban-rural wealth disparities. In this paper, I examine the impact of the introduction of HSRs on the income disparity between urban and rural residents in China. Using panel data from 285 prefecture-level cities from 2004 to 2018, in this paper I employ the double-difference method to assess the impact of HSR on the income gap between urban and rural populations and the mechanism of its action; furthermore, I explore the influence of HSR on urban residents' per capita disposable income and rural residents' per capita net income, as well as the impact of HSR on the flow of elements such as labor and capital. My research findings reveal that the introduction of HSR has greatly widened the income gap between urban and rural residents; however, there is heterogeneity between different East, Central, and West regions, as well as between different levels of cities. A further mechanism study finds that HSR lowers farmers' per capita net income, raises urban residents' per capita disposable income, and widens the urban/rural income gap via mechanisms such as facilitating the interregional mobility of labor and capital factors. Therefore, it is necessary to comprehensively assess the economic effects brought about by HSR, strengthen the construction of urban-rural transport networks, and improve support for rural areas, so as to promote the coordinated development of inter-regional and urban-rural areas. [ABSTRACT FROM AUTHOR]

Background: Staphylococcus aureus (S. aureus) is a common cause of bacteremia, which leads to significant morbidity and mortality. We investigated the relationship between time to positivity (TTP) and clinical outcomes in children with S.aureus bacteremia in the China.Methods: A retrospective study of Staphylococcus aureus bacteremia inpatient was performed in Children's Hospital of Chongqing Medical University in China between 29 January 2014 and 29 August 2017. TTP and clinical parameters were determined and analyzed. The receiver operating characteristic (ROC) curves were plotted for optimal cut-off selection, multivariate logistic regression tests were performed to evaluate the association between TTP and clinical outcomes.Results: Overall, 84 cases were enrolled. We stated that in-hospital mortality is significantly higher in the early TTP (≤17 h) than in the late TTP (> 17 h) group (57.14% vs 7.14%, P = 0.000). Septic shock occurred in 57.14% of patients with early TTP and in 18.57% of patients with late TTP (P = 0.002). Detailed multivariate and statistical analysis revealed that early TTP, need for vasoactive agent were independent risk factors of in-hospital mortality; early TTP, need for vasoactive agent and APACHE II score ≥ 15 were independent risk factors of septic shock incidence in S. aureus bacteremia children.Conclusions: Overall, TTP of ≤17 h appeared to correlate with the worse outcomes for S. aureus bacteremia children. These results have important implications in the assessments and management of pediatric S. aureus bacteremia in a clinical setting.Trial Registration: Retrospectively registered. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) has become the main air pollutant in most cities of in China, which greatly threatens the human health. Numerous studies have reported that PM concentrations could be accurately predicted from previous days' meteorological conditions. However, the hysteretic or lagged effects of meteorological factors on PM concentrations are not clear. In this study, the GeoDetector q statistic method was used to quantify the hysteretic influences of meteorological conditions and their interactions on concentrations of PM 2.5 (particles < 2.5 μm in aerodynamic diameter) and PM 10 (particles < 10 μm in aerodynamic diameter) and the ratio of PM 2.5 to PM 10 (PM 2.5 /PM 10) at multiple spatial and temporal scales in China. We found that the temperature, precipitation, and relative humidity had primary impacts on PM 2.5 concentrations, PM 10 concentrations, and the PM 2.5 /PM 10 ratios, respectively, at both national and annual time scales. At the seasonal time scale, precipitation and relative humidity had hysteretic effects on PM concentrations in spring and summer, respectively. Moreover, precipitation and wind speed were dominant hysteretic factors in autumn and winter, respectively. At the regional scale, the dominant hysteretic effects of meteorological factors showed large variations across all regional subdivisions. The interactions between any two meteorological factors had an enhanced hysteretic effect on PM concentrations compared to a single factor. These findings could help us to develop scientific measures to reduce the emissions of air pollution and improve the performance of air pollution prediction models. Image 1 • Hysteretic effects of meteorological factors on particulate matter were identified. • Temperature, rainfall, and humidity are main lagged factors of particulate matter. • Regional and seasonal variations of hysteretic factors were identified in China. • Urgent need to explore mechanisms of lagged effects of meteorological factors on PM. [ABSTRACT FROM AUTHOR]