Natural ventilation driven by a restricted heat source elevated to different levels

The thermal buoyancy generated by the difference in air density in a building can drive hot-pressed natural ventilation,which is an energy-efficient means of ventilation used to obtain higher air quality.Therefore,the effect of a single-point heat source with limited sides at different heights on stratified flow was studied in a naturally ventilated room in this paper.Based on the classical plume diffusion law of an independent point heat source and the mirroring principle,a calculation model of the thermal stratification height with a restricted source elevated to different levels was derived and validated.The quantitative effects of the heat source height from the floor,the effective opening area and other factors on the natural ventilation of hot pressure were analyzed.A threshold X_(T)for the separation between a point source and a sidewall was defined to estimate whether the thermal plume was independent or restricted by a sidewall.And a method for calculating the threshold xt was obtained.This research can provide a reference basis for designing natural ventilation for buildings with a restricted heat source at different levels to achieve a desired indoor environment.

THE RELATIONSHIP BETWEEN THE ERYTHROCYTE POLYAMINE LEVELS AND THE DIFFERENT TYPES OF LEUKEMIA

In a study on erythrocyte polyamine levels in 20 leukemia patients and 18 healthy individuals, following results were obtained. Putrescine(Pu) in ery-throcytes was nearly undetectable but in 2 AMoL patients; Spermidine(Spd) level in ALL was higher than the control volue (P<0.05), in AML (M1, M2) and APL the Spd level was in the range of control group (P>0.1), while that in AMoL and AMMoL was considerably lower as compared to control (P< 0.001); Spermine (Spm) level in all types of leukemia was increased (P<0.001); Spd/Spm ratio was significantly decreased, showing 1.525 in control group, 0.938 in ALL (P<0.025), 0.779 in AML (M1, M2) P< 0.01), 0.319 in APL (P<0.001) and 0.296 in AMoL & AMMoL (P<0.001), and the differences between the Spd/Spm ratio in AMoL and AMMoL and in ALL were noted (P<0.05). These results suggested that determination of erythrocyte polyamines in leukemia patients may be helpful in diagnosis, differential diagnosis and prognosis.

Influence of the Different Level Ammonium on NRA and GSA in Sugar Beet(Vulgaris L.)

Ammonium nitrogen inhibited NR activity in sugar beet,NR activity was lower in endogenous substrate after ammonium nitrogen was used,and the correlation between NR activity and ammonium nitrogen levels was negative.But NR activity raised with the ammonium nitrogen levels raising in exogenous.Ammonium nitrogen prompted GS activity:the correlation between GS activity and ammonium nitrogen was positive,GS activity raised with ammonium nitrogen levels raising,GS activity of roots and leaves had same change trend in sugar beet in the whole growth duration after ammonium nitrogen was used,but GS activity in roots was higher than that in leaves.

常州市各级医院带量采购政策实施效果差异研究

目的评价第二批国家集中带量采购(以下简称“集采”)政策在常州市不同等级医院的实施效果。方法基于双组间断时间序列模型和描述性统计,依托江苏省常州市医疗机构药品采购数据,分析第二批国家集采政策实施对江苏省常州市二级及以上医院和基层医疗卫生机构用药影响差异。结果第二批国家集采政策实施后,常州市二级及以上医院和基层医疗卫生机构集采品种均呈现不同程度药品使用频度(defined drug dose numbers,DDDs)上升、采购金额下降和药品日均费用(defined daily dose cost,DDDc)下降的现象,其中对于基层医疗卫生机构集采中选品种使用增长效果更明显,在具体药物种类上,心血管系统类、消化系统类药物受政策影响更明显。结论政府应该根据不同医院的用药特点制定更为灵活、有针对性的集采品种使用考核标准,并将考核细化到不同种类药品的使用情况。此外,政府相关部门应持续性检测各级医院的合理用药情况,并通过奖惩制度提高医疗机构使用集采品种的积极性。

Dynamic channel reservation scheme based on priorities in LEO satellite systems

According to low earth orbit（LEO） satellite systems with users of different levels, a dynamic channel reservation scheme based on priorities is proposed. Dynamic calculation of the thresholds for reserved channels is the key of this strategy. In order to obtain the optimal thresholds, the traffic is predicted based on the high-speed deterministic movement property of LEO satellites firstly. Then, a channel allocation model based on Markov is established. Finally, the solution of the model is obtained based on the genetic algorithm. Without user location, this strategy effectively reduces handover failures and improves channel utilization by adjusting dynamically the thresholds according to traffic conditions. The simulation results show that the system＇s overall quality of service can be improved by this strategy.

Study of broadband THz time-domain spectroscopy at different relative humidity levels

Two detection techniques of broadband terahertz（THz）time-domain spectroscopy-THz air-biased coherent detection（THz-ABCD;from 0.3 to 14 THz）and electro-optical（EO）detection（from 0.3 to 7 THz）-are both performed at several different relative humidity levels.The THz power exponentially decays with the increase in relative humidity.The dynamic range of the main pulse in the time domain linearly decreases as the relative humidity increases from 0%to 40%,and linear fittings show that the slopes are-0.017 and-0.019 for THz-ABCD and EO detection,respectively.Because of the multiple reflections caused by the crystal in the common EO detection,THz-ABCD has better spectral resolution（17 GHz）than that of EO detection（170 GHz）.The spectrum of water vapor absorption measured by THz-ABCD is also compared with that measured by the Fourier transform infrared spectroscopy（FTIR）.

Pollution Characteristics and Health Risk Assessment of Heavy Metals in PM2.5 during Winter in the Suburb of Cangzhou, China

The heavy metals in atmospheric fine particles are of great concern to human health. To understand the pollution characteristics and health risks of heavy metals in particulate matter with an aerodynamic equivalent diameter ≤2.5 μm (PM2.5) during winter in the suburb of Cangzhou, PM2.5 samples were collected with an intelligent medium-flow atmospheric particulate matter sampler from January to February 2019. The Fe, Cu, Mn, Pb and Zn contents in PM2.5 were determined via inductively coupled plasma optical emission spectrometry (ICP-OES). The sources and health risks of heavy metals in PM2.5 were analysed via the enrichment factor (EF) method and the United States Environmental Protection Agency (US EPA) health risk assessment model. The results showed that the average PM2.5 concentration in the suburb of Cangzhou reached 71.6 μg/m3, ranging from 23.7 to 169.5 μg/m3. The exceeding standard rate was 29.4% during the sampling period. The PM2.5 concentration during the nighttime was higher than that during the daytime. The heavy metal concentrations in PM2.5 decreased in the order of Fe > Mn > Zn > Cu > Pb, and the Fe, Mn, Pb and Zn concentrations decreased in the order of clean days < pollution days < heavy pollution days. The Fe and Mn concentrations were higher during the daytime than those during the nighttime, while the Cu, Pb and Zn concentrations were higher during the nighttime than those during the daytime. EF analysis revealed that Zn, Pb and Cu were significantly enriched, and Pb was highly enriched on heavy pollution days with increasing pollution degree. The enrichment level of heavy metals during the nighttime was higher than that during the daytime. Health risk assessment demonstrated that Mn posed non-carcinogenic risks to both adults and children, following the sequence of clean days < pollution days < heavy pollution days. Pb posed a carcinogenic risk to adults on heavy pollution days. The study revealed that the pollution levels of heavy metals in PM2.5 in the suburb of Cangzhou were low, and Pb and Mn in PM2.5 posed certain health risks to the population.

The effects of thyroid-stimulating hormone,estradiol and prolactin on sodium/iodide symporter mRNA expression in mouse lactating mammary gland cells under different iodine levels

Objective The present study investigated the sodium/iodide symporter mRNA expression in mouse lactating mammary gland cells under different iodine levels and the effects of thyroid-stimulating hormone(TSH),estradiol(E2)and prolactin(PRL)on NIS mRNA expression in mouse lactating mammary gland cells.

Assessment of Flue Gas Reinjecting Operating Strategy in Performance of CCHP System using Energy Level Difference Analysis

A proper operating strategy is helpful to improve the off-design performance of combined cooling,heating and power(CCHP)systems,providing high efficiency and low emission.The energy level difference graphic analysis method is used to identify energy level as well as exergy destruction of the part-load process.This method illustrates the energy efficiency upgrading mechanism of the flue gas reinjecting(FGR)operating strategy.It is referenced to a reducing turbine inlet temperature(TIT)operating strategy.By comparison,the FGR operating strategy leads to a 2.62%exergy distribution reduction in a gas turbine at an 85%load level due to the decrease of the energy level difference.When the output power is reduced further,the FGR operating strategy is supplanted by the TIT operating strategy with the limit of compressor inlet temperature.However,the opposite results of exergy distribution are presented in the exhaust-heat recovery devices.A heat-driven refrigeration and power cycle is introduced in a typical CCHP system as a solution.Moreover,the results suggest that the operational flexibility of the CCHP system is improved by enlarging the ratio of cooling to electricity.