Search

• Evaluation of decay heat removal systems of FHR during thermal-hydraulic transient was performed. • Heat removal performances of FHR systems are investigated. • FHR's decay heat removal system shows sufficient heat removal capability to avoid catastrophic accidents. The Fluoride-salt-cooled High-temperature Reactor (FHR) is one of the Generation IV nuclear reactor concepts being investigated mainly in the U.S. and China. Liquid salt with high boiling point of over 1400 °C is used as a coolant and its baseline fuel is the graphite-matrix coated-particle fuel developed for high-temperature gas-cooled reactors. To establish advanced safety systems in FHR, passive decay heat removal system which utilizes fluid's natural circulation is considered. Three systems are proposed: Direct Reactor Air Cooling System (DRACS), Reactor Vessel Air Cooling System (RVACS), and Silo Cooling System (SCS). Although these three safety systems were previously developed for other types of reactors, their heat removal performances need to be evaluated for the FHR plant. The current study provides evaluation of decay heat removal systems of FHR during thermal-hydraulic transient. In addition, FHR's grace period to start the reactor cooling was determined under the condition where no operable heat removal systems are available. The current study shows that FHR's decay heat removal systems possess sufficient heat removal capability to avoid catastrophic accidents. The construction of Fluoride-salt-cooled High-temperature Test Reactor (FHTR) is currently being planned and its development is a key step to realize the commercialization in near future. This study provides performance evaluation of decay heat systems for FHTR under thermal-hydraulic transient, and also suggests the adequate operation procedure suitable for FHTR to avoid a severe accident. [ABSTRACT FROM AUTHOR]

China and Japan share numerous similarities other than their geographical proximity. Facing the great challenges of non-communicable diseases (NCDs), China and Japan have developed different preventive strategies and systems. While Japan has made great progress in primary prevention of NCDs through strong legislation, the 'Specific Health Check and Guidance System' and a unique licensed health professional system, China is attempting to catch up by changing its strategies in NCDs control. In this manuscript, we compared disease burden of NCDs, health care systems and preventive strategies against NCDs between China and Japan. In this light, we summarized the points that the two countries can learn from each other, and proposed recommendations for the two countries in NCDs control. [ABSTRACT FROM AUTHOR]

We investigate heavy haze episodes (with dense concentrations of atmospheric aerosols) occurring around Beijing in June, when serious air pollution was detected by both satellite and ground measurements. Aerosol retrieval is achieved by radiative transfer simulation in an Earth atmosphere model.We solve the radiative transfer problem in the case of haze episodes by successive order of scattering.We conclude that air pollution around Beijing in June ismainly due to increased emissions of anthropogenic aerosols and that carbonaceous aerosols from agriculture biomass burning in Southeast Asia also contribute to pollution. [ABSTRACT FROM AUTHOR]

Concentrations of persistent organochlorines (OCs), such as DDTs, hexachlorocyclohexanes (HCHs), hexachloro-benzene (HCB), polychlorinated biphenyls (PCBs), and chlordane compounds (CHLs) were determined in 34 human adipose tissues collected from Guizhou Province, southern China, during 2002. DDT was the predominant contaminant among OCs analyzed; concentrations ranged from 420 to 20 000 ng/g on a lipid wt basis (average ± sd: 5700 ± 4100 ng/g). Concentrations of DDTs and the ratio of p,p'-DDT/ ΣDDT in humans in China were significantly higher than those reported for developed countries. DDT levels in humans in Guizhou Province were comparable to those from Shanghai City, implying the presence of significant sources of DDTs in inland and coastal areas in China. Age-dependent accumulation of HCH concentration was found in this study, possibly because of the considerable reduction in average dairy intake (ADI) of HCHs by Chinese during the recent two decades. On the basis of the information of the ADI rates, half-lives, and body burdens of DDTs, the magnitude of historical DDT exposures by Chinese was estimated. This suggested that approximately 80% of DDTs deposited in Chinese adipose tissues was accumulated before the 1990s. The monitoring of OC levels and epidemiological studies are needed in China to understand the status of contamination and the risks to humans. [ABSTRACT FROM AUTHOR]

Free tropospheric aerosol particles were collected using a balloon-borne particle impactor in August of 2002 and March of 2003 at Dunhuang in northwestern China (40°00′N, 94°30′E), and the morphology and elemental composition of the aerosol particles were analyzed in order to understand the mixing state of coarse dust particles (diameter >1 μm) over the desert areas in the Asian continent in spring. Electron microscopic experiments on the particles revealed that dust particles were major constituents of coarse mode particles in the free troposphere over the Taklamakan Desert in spring and summer. Si-rich or Ca-rich particles are major components of dust particles collected in the free troposphere over dunhuang and the values of [number of Ca-rich particles]/[number of Si-rich particles] differs markedly between spring and summer, being about 0.3 in the spring of 2003 and about 1.0 in the summer of 2002 at heights 3–5 km above sea level. It is likely that the condition of the ground surface and the strength of vertical mixing in source areas of Asian dust are potential factors causing the difference in the chemical types of dust particles. Comparison of the elemental compositions of these particles with those of particles collected over Japan strongly suggests that these particles were chemically modified during their long-range transport in the free troposphere. Analysis of wind systems shows that both the predominating westerly wind in the free troposphere and the surface wind strongly controlled by the geographical structure of the Tarim Basin are important in the long-range transport of KOSA particles originating in the Taklamakan Desert. [ABSTRACT FROM AUTHOR]

This study focuses on providing a direct insight into the process by which sulfate is formed on mineral dust surface in the actual atmosphere. Six sets of aerosol measurements were conducted in the outskirts of Beijing, China, in 2002–2003 using a tethered balloon. The mineralogy of individual dust particles, as well as its influence on the S (sulfur) loadings was investigated by SEM-EDX analysis of the directly collected particles. The mixed layer in the urban atmosphere was found to be quite low (500–600m), often appearing as a particle dense stagnant layer above the surface. It is suggested that mineral dust is a common and important fraction of the coarse particles in Beijing (35–68%), and that it is relatively enriched with Calcite (>28%). An exceptional amount of S was detected in the mineral particles, which can be explained neither by their original composition, nor by coagulation processes between the submicron sulfates and the dust. Heterogeneous uptake of gaseous SO2, and its subsequent oxidation on dust was suggested as the main pathway that has actually taken place in the ambient environment. The mineral class found with the largest number of particles containing S was Calcite, followed by Dolomite, Clay, Amphibole etc., Feldspar, and Quartz. Among them, Calcite and Dolomite showed distinctly higher efficiency in collecting sulfate than the other types. A positive correlation was found with the number of S containing particles and the relative humidity. Calcite in particular, since almost all of its particles was found to contain S above 60% r.h. On the other hand, the active uptake of SO2 by the carbonates was not suggested in the free troposphere downwind, and all the mineral classes exhibited similar S content. Relative humidity in the free troposphere was suggested as the key factor controlling the SO2 uptake among the mineral types. In terms of sulfate loadings, the relationship was not linear, but rather increased exponentially as a function of relative humidity. The humidity-dependent uptake capacity of mineral types altogether showed an intermediate value of 0.07 gSO42− g−1 mineral at 30% r.h. and 0.40 gSO42− g−1 mineral at 80%, which is fairly consistent with laboratory experiments. [ABSTRACT FROM AUTHOR]

Contamination by persistent organochlorines (OCs), such as DDTs, hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs) were examined in sediments, soils, fishes, crustaceans, birds, and aquaculture feed from Lake Tai, Hangzhou Bay, and in the vicinity of Shanghai city in China during 2000 and 2001. OCs were detected in all samples analyzed, and DDT and its metabolites were the predominant contaminants in most sediments, soils and biota. Concentrations of p,p′-DDT and ratio of p,p′-DDT to ∑DDTs were significantly higher in marine fishes than those in freshwater fishes. While the use of DDTs has been officially banned in China since 1983, these results indicate a recent input of technical DDTs into the marine environment around Hangzhou Bay. Comparison of organochlorine concentrations in fishes collected from Lake Tai and Hangzhou Bay suggests the presence of local sources of HCHs, chlordanes and PCBs at Lake Tai. Higher proportions of penta- and hexa-PCB congeners in fishes at Lake Tai may suggest the use of highly chlorinated PCB product, such as PCB5, around this lake. To our knowledge, this is a first comprehensive study to examine the present status of organochlorine contamination in various environmental media, such as sediments, soils and wildlife, in China. [Copyright &y& Elsevier]

Measurements of aerosol were made in August and October 2001, and January 2002, at Dunhuang, China (40°00′N, 94°30′E), to understand the nature of atmospheric particles over the desert areas in the Asian continent. Balloon-borne measurements with an optical particle counter suggested that particle size and concentration had a noticeable peak in size range of super micron in not only the boundary mixing layer but also the free troposphere. Thickness of the boundary mixing layer, from distributions of particle concentration, was about 4 km in summer (17 August 2001), about 2.5 km in fall (17 October 2001), and about 3 km in winter (11 January 2002), which suggest active mixing of particles near the boundary in summer. Number-size distribution of particle showed a noticeable peak in the super micron particles size range in the mixing boundary layer: 0.4–2 particles cm-3 at diameter >1.2 μm in summer, 0.05–4 particles cm-3 at diameter >1.2 μm in fall, and 0.1–5 particles cm-3 at diameter >1.2 μm in winter. In winter strong inversion of atmospheric temperature was found in the height range from the boundary to about 3 km and vertical distribution of particle concentration well corresponded with the temperature distribution. Chemical elements of individual aerosols, which were collected in the boundary layer atmosphere at Dunhuang (18 October 2001) were analyzed with an electron microscope equipped with EDX. Those single particle analysis suggested that most of the particles with super micron size were soil particles, and those particles had little sulfate on its surface. This is a very important different point, comparing with the chemical state of soil particles, which were transported from the desert area of China to Japan, and showed frequently the existence of sulfate on the particle surface. Therefore, it is strongly suggested that dust particles can be chemically modified during their long-range transport from desert areas to Japan. [ABSTRACT FROM AUTHOR]

Vertical changes of aerosol concentration and size in the free troposphere over the Asian desert areas were firstly observed using a balloon-borne optical particle counter at DunHuang, China (40°00′N, 94°30′E) (17 August and 17 October 2001, and 11 January 2002). In the free troposphere highly concentrated aerosol layers were frequently observed, suggesting the importance of regional scale particle transportation over the Asian continent. Concentration of particles with a diameter larger than 0.15 μm was about 5–10 particles cm-3 in the free troposphere. Particle number-size distribution in the free troposphere shows important contribution of super micron particles. Regional scale transportation, in addition to diffusion of soil particles from the lower atmosphere to the free troposphere through local and small scale air motions, is suggested by backward trajectory analysis of air masses containing super micron particles. The importance of horizontal transport of coarse size particles in the free troposphere was strongly suggested. Thickness of the boundary mixing layer, from distributions of particle concentration, was about 4 km in summer (17 August 2001) and apparently higher than the height of layers in fall (17 October 2001) and in winter (11 January 2002), which suggest an active mixing of particles near the boundary in summer. In winter measurement (11 January 2002), strong inversion was found in the vertical profile of temperature, suggesting cold ground surface and vertically stable atmosphere near the ground. [ABSTRACT FROM AUTHOR]

To investigate the evolution of the nocturnal boundary layer (NBL) and its impacts on the vertical distributions of pollutant particulates, a combination of in situ observations from a large tethered balloon, remote sensing instruments (aerosol lidar and Doppler wind lidar) and an atmospheric environment-monitoring vehicle were utilized. The observation site was approximately 100 km southwest of Beijing, the capital of China. Results show that a considerable proportion of pollutant particulates were still suspended in the residual layer (RL) (e.g., the nitrate concentration reached 30 μg m−3) after sunset. The NBL height calculated by the aerosol lidar was closer to the top of the RL before midnight because of the pollutants stored aloft in the RL and the shallow surface inversion layer; after midnight, the NBL height was more consistent with the top of the surface inversion layer. As the convective mixing layer gradually became established after sunrise the following day, the pollutants stored in the nocturnal RL of the preceding night were entrained downward into the mixing layer. The early morning PM2.5 concentration near 700 m in the RL on 20 December decreased by 83% compared with the concentration at 13:34 on 20 December at the same height. The nitrate concentration also decreased significantly in the RL, and the mixing down of nitrate from the RL could contribute about 37% to the nitrate in the mixing layer. Turbulence activities still existed in the RL with the bulk Richardson number (Rb) below the threshold value. The corresponding increase in PM2.5 was likely to be correlated with the weak turbulence in the RL in the early morning. [ABSTRACT FROM AUTHOR]

[Display omitted] • Higher COD/N ratio in DNF operation led to more aggravated membrane fouling. • Fouling of DNF effluent: glucose > methanol > ethanol > sodium acetate-fed HOA and HON fractions in DNF effluent dominated subsequent UF membrane fouling. • DNF operation could alleviate UF fouling by regulating external carbon addition. • DNF-UF process should be optimized as an integrated system rather than separate units. The process of denitrification filter (DNF) followed by ultrafiltration (UF) has been widely applied for wastewater reclamation in China. The performance of DNF could have significant influences on subsequent UF membrane fouling. In this study, different chemical oxygen demand to nitrogen (COD/N) ratios and carbon sources in DNF were investigated under pilot scale, with the secondary effluent of a wastewater reclamation plant as DNF influent, to explore the impacts of DNF operation on UF membrane fouling. DNF effluent with the increased COD/N ratios from 2.9 to 6.8 rendered more aggravated membrane fouling performance, suggesting that increase of carbon source dosage could significantly increase the fouling potential of DNF effluent. In terms of four commonly-used carbon sources, the fouling potential was higher in the order of glucose > methanol > ethanol > sodium acetate-fed DNF effluent. According to the resin fractionation and fluorescence spectroscopy analysis, water samples with higher membrane fouling potential contained a larger proportion of hydrophobic components. Extended Derjaguin Landau Verwey Overbeek (XDLVO) analysis revealed fouling mechanism that hydrophobic acids (HOA) and hydrophobic neutrals (HON) exhibited both notably attractive interaction with virgin membranes and a strong tendency to aggregate on the already fouled membranes. Compared with the other fractions, HOA and HON presented significantly stronger interaction energy, demonstrating that HOA and HON dominated the membrane fouling process. Therefore, the contents of HOA and HON fractions in DNF effluent could be effectively regulated by optimizing external carbon addition, thus alleviating the subsequent UF fouling. The DNF-UF process should be considered and optimized as an integrated system rather than independent units, and appropriate external carbon addition should be regulated to achieve an optimal process from the perspective of the whole wastewater reclamation plant. [ABSTRACT FROM AUTHOR]

In 2006–2007, we collected human milk from 60 and 48 donors in the Chinese coastal cities of Tianjin and Yantai, respectively, in accordance with the WHO/UNEP global milk survey. We determined the concentrations of organochlorine pesticides by GC/MS/MS and dioxins by XDS-CALUX bioassay in the individual milk specimens. The geometric mean concentrations (GMs) of β-HCH (586.7ng g−1 fat), total DDTs (855.9ngg−1 fat), and dl-PCBs (4.4pg CALUX-TEQg−1 fat) in the milk from Yantai were higher than those from Tianjin (254.4ng g-1 fat, 654.7ngg−1 fat, 1.9pg CALUX-TEQ g−1 fat, respectively). However, the GMs of HCB (41.1ngg−1 fat) and PCDD/Fs (13.1pg CALUX-TEQg−1 fat) from Tianjin were higher than those from Yantai (15.7ng g−1 fat, 9.9pg CALUX-TEQ g−1 fat). The low ratios of DDT/(DDE+DDD) in milk from both areas suggested that past exposure contributed to the total DDTs body burden. The dl-PCBs body burden in the high sea fish intake group was higher than that in the low intake group, both with and without adjustments for potential influencing factors. For β-HCH, a marginal P value (P =0.063) was observed between high and low sea fish consumption groups after adjusting for potential influencing factors. Donors in the high freshwater fish group showed higher PCDD/Fs and HCB levels than those in the low intake group, both with and without adjustments. Further monitoring studies of POPs contamination in human milk and foods are needed in China. [Copyright &y& Elsevier]

Objective: To investigate the co-effect of Demand-control-support (DCS) model and Effort-reward Imbalance (ERI) model on the risk estimation of depression in humans in comparison with the effects when they are used respectively., Methods: A total of 3 632 males and 1 706 females from 13 factories and companies in Henan province were recruited in this cross-sectional study. Perceived job stress was evaluated with the Job Content Questionnaire and Effort-Reward Imbalance Questionnaire (Chinese version). Depressive symptoms were assessed by using the Center for Epidemiological Studies Depression Scale (CES-D)., Results: DC (demands/job control ratio) and ERI were shown to be independently associated with depressive symptoms. The outcome of low social support and overcommitment were similar. High DC and low social support (SS), high ERI and high overcommitment, and high DC and high ERI posed greater risks of depressive symptoms than each of them did alone. ERI model and SS model seem to be effective in estimating the risk of depressive symptoms if they are used respectively., Conclusion: The DC had better performance when it was used in combination with low SS. The effect on physical demands was better than on psychological demands. The combination of DCS and ERI models could improve the risk estimate of depressive symptoms in humans., (Copyright © 2013 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.)

The purpose of this study was to examine the association between psychosocial job stress (by the Job Control-Demand (JCD) model and Effort-Reward imbalance (ERI) model) and musculoskeletal (MS) symptoms among workers in China. Overall, 3,632 male and 1,706 female workers from 13 factories/companies participated in this study. Perceived job stress was evaluated by the Chinese version of the Job Content Questionnaire (JCQ) and ERI Questionnaire. Neck, shoulder and wrist symptoms were assessed by self-report during the past year. Workers reporting high job demands and low job control or high effort and low rewards had moderately increased risk for all MS symptoms. Odds ratios (ORs) were higher in workers reporting both high effort and low rewards. The combination of high physical job demands with low job control showed significant associations with MS symptoms. The effects of psychological demands on symptoms in women, effort and effort-reward imbalance on symptoms among both genders were increased as the number of regions with symptoms increased. These results suggest that high job strain and ERI are associated with neck, shoulder and wrist symptoms in Chinese factory workers independent of individual factors, physical factors, and other psychological variables.