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排序方式: 共有2473条查询结果,搜索用时 67 毫秒
1.
G. C. Morrison H. V. Andersen L. Gunnarsen D. Varol E. Uhde B. Kolarik 《Indoor air》2018,28(1):188-197
Polychlorinated biphenyl (PCB) contamination of buildings continues to pose an exposure threat, even decades after their application in the form of calks and other building materials. In this research, we investigate the ability of clothing to sorb PCBs from contaminated air and thereby influence exposure. The equilibrium concentration of PCB‐28 and PCB‐52 was quantified for nine used clothing fabrics exposed for 56 days to air in a Danish apartment contaminated with PCBs. Fabric materials included pure materials such as cotton and polyester, or blends of polyester, cotton, viscose/rayon, and/or elastane. Air concentrations were fairly stable over the experimental period, with PCB‐28 ranging from 350 to 430 ng/m3 and PCB‐52 ranging from 460 to 550 ng/m3. Mass accumulated in fabric ranged from below detection limits to 4.5 mg/g of fabric. Cotton or materials containing elastane sorbed more than polyester materials on a mass basis. Mass‐normalized partition coefficients above detection limits ranged from 105.7 to 107.0 L/kg. Clothing acts as a reservoir for PCBs that extends dermal exposure, even when outside or in uncontaminated buildings. 相似文献
2.
Measuring cognitive load is important in virtual learning environments (VLE). Thus, valid and reliable measures of cognitive load are important to support instructional design in VLE. Through three studies, we investigated the validity and reliability of Leppink's Cognitive Load Scale (CLS) and developed the extraneous cognitive load (EL) dimension into three sub-scales relevant for VLE: EL instructions, EL interaction, and EL environment. We investigated the validity of the measures using the Partial Credit Model (PCM), Confirmatory Factor Analysis (CFA), and correlations with retention tests. Study 1 (n = 73) investigated the adapted version of the CLS. Study 2 describes the development and validation of the Multidimensional Cognitive Load Scale for Virtual Environments (MCLSVE), with 140 students in higher education. Study 3 tested the generalizability of the results with 121 higher education students in a more complicated VLE. The results provide initial evidence for the validity and reliability of the MCLSVE. 相似文献
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4.
Sarah Gilgunn Keefe Murphy Henning Stckmann Paul J. Conroy T. Brendan Murphy R. William Watson Richard J. OKennedy Pauline M. Rudd Radka Saldova 《International journal of molecular sciences》2020,21(23)
The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies. 相似文献
5.
Mark Winter Erling S. Andersen Roger Elvin Ralph Levene 《International Journal of Project Management》2006,24(8):699
An important development in project management in recent years has been the emergence of a new class of projects, in areas such as organisational change and IT, integrated business solutions, and long-term public service delivery. Often referred to as ‘business projects’, this new class of projects (and programmes) reflects a growing conceptual shift away from the traditional engineering view of projects, towards a more business-oriented view, in which the primary concern is no longer the capital asset, system or facility etc, but increasingly the challenge of implementing business strategy, improving organisational effectiveness, and managing the realisation of stakeholder benefits. Drawing on recent research from the UK Government-funded Rethinking Project Management Network, this paper argues that future research in this area needs to look beyond the mainstream literature on project management, to other relevant disciplines such as strategic management, operations management, and the management of change. Against this background, the authors present four conceptual perspectives from the management literature, which can be usefully applied to business projects. They represent exploratory contributions from four participants in the Network – a special collaboration between researchers – whose ideas and perspectives were either discussed at the Network meetings, or are the subject of research elsewhere. Collectively, the four contributions represent an exploratory discussion of different theoretical perspectives, in order to inform and stimulate other researchers and practitioners working in the field. 相似文献
6.
Johansen P Mulvad G Pedersen HS Hansen JC Riget F 《The Science of the total environment》2006,372(1):58-63
In the Arctic, the traditional diet exposes its people to a very high intake of cadmium because it is highly concentrated in the liver and kidneys of commonly eaten marine mammals. In one study in Greenland, the cadmium intake was estimated to 182 microg/day/person in the fall and 346 in the spring. To determine whether the cadmium is accumulated in humans, we analyzed autopsy samples of liver and kidneys from 95 ethnic Greenlanders (aged 19-89) who died from a wide range of causes. The cadmium concentration in liver (overall mean 1.97 microg/g wet wt) appeared to be unrelated to any particular age group, whereas the concentrations in the kidneys peaked in Greenlanders between 40 and 50 years of age (peak concentration 22.3 microg/g wet wt). Despite the high cadmium levels in the typical Greenlander diet, we found that the cadmium concentrations in livers and kidneys were comparable to those reported from Denmark, Sweden, Australia and Great Britain. Furthermore, even though the mean cadmium intake from the diet was estimated to be 13-25 times higher in Greenlanders than in Danes, we found similar cadmium levels in the kidneys of both. Seal livers and kidneys are the main source of cadmium in the diet of Greenlanders, but these tissues are not eaten in Denmark. Thus, our results suggest that the accumulation of cadmium from Greenlander's marine diet is very low. 相似文献
7.
OBJECTIVES: The purpose of this study is to monitor and assess human exposure to pollution in the Arctic which presents a potential future health risk for the local populations. Epidemiological studies in Greenland have shown that human blood levels of several organic contaminants are very high, especially in the North where people depend on local food. In East Greenland (Ittoqqortoormiit (Scoresbysund)) the population shows the highest blood levels of several persistent organic pollutants found in Arctic countries, especially PCB, the levels of which exceed Canadian guideline levels. As in other Arctic countries, the predominant source of these contaminants is the local diet. However, other factors such as smoking may influence the metabolism and thereby the accumulation of toxic substances. STUDY DESIGN: This project is part of the human health program of the ongoing circumpolar "Artic Monitoring and Assessment Programme". Lifestyle, anthropometric factors, and dietary survey results covering 500 men and women from 6 Greenlandic districts were analyzed along with other factors blood lipids, fatty acid profiles, heavy metals and concentrations of persistent organic pollutants (POPs). RESULTS: The dietary survey showed that the traditional food on the average provided 20-30% of the total energy intake. However, the relative monthly meal intake of seal, whale, polar bear, fish and game, and the composition of imported food, varied between districts. Seal and polar bear intake, and, in particular all the plasma n-3 fatty acids, were significantly correlated with organic contaminant concentrations, (betaHCH, chlordanes, DDTs, Hexachlorobenzene, Mirex, PCBs, and toxaphenes) p<0.01(). After adjusting for age, district, dietary factors or plasma n-3 fatty acids, smoking was significantly correlated with high levels of all the above mentioned POPs. CONCLUSION: The main predictors of high contaminant levels in Greenland were age, district, male gender, smoking and high plasma n-3/n-6 ratio as a marker of high dietary intake of local marine mammals. 相似文献
8.
T. M. Korves Y. M. Piceno L. M. Tom T. Z. DeSantis B. W. Jones G. L. Andersen G. M. Hwang 《Indoor air》2013,23(1):50-61
Practical Implications
A biosensor that could be deployed in commercial aircraft would be required to function at an extremely low false alarm rate, making an understanding of microbial background important. This study reveals a diverse bacterial background present on aircraft, including bacteria closely related to pathogens of public health concern. Furthermore, this aircraft background is different from outdoor air, suggesting different probes may be needed to detect airborne contaminants to achieve minimal false alarm rates. This study also indicates that aircraft HEPA filters could be used with other molecular techniques to further characterize background bacteria and in investigations in the wake of a disease outbreak.9.
Concentrations and patterns of organochlorine contaminants in white whales (Delphinapterus leucas) from Svalbard, Norway 总被引:2,自引:0,他引:2
Andersen G Kovacs KM Lydersen C Skaare JU Gjertz I Jenssen BM 《The Science of the total environment》2001,264(3):267-281
Blubber was collected from live-captured, adult male white whales (Delphinapterus leucas) from Svalbard, Norway, and analysed for levels and patterns of organochlorine (OC) contaminants. The OC compounds analysed were HCB, dieldrin, sigmaHCH (alpha-HCH, beta-HCH and gamma-HCH), sigmaChl (heptachlor epoxide, oxychlordane, cis-chlordane, trans-nonachlor, and cis-nonachlor), sigmaDDT (pp'-DDT, pp'-DDE and pp'-DDD) and sigmaPCB (27 PCB congeners). The major OC compounds detected in the blubber were sigmaPCB (5103+/-1874 ng/g l.w.) and sigmaDDT (5108+/-1089 ng/g l.w.), which made up 70% of the sigmaOC. These compounds were followed in prevalence by sigmaChl (2872+/-1177 ng/g l.w.), which contributed 20% of the sigmaOC burden. SigmaHCH, HCB and dieldrin were present, but at low concentrations. This OC pattern is typical of top predators in Arctic marine food chains. OC levels in white whales from Svalbard are lower than white whales from the St Lawrence River in Canada and are generally similar to values reported previously for other Arctic white whale stocks. Some geographic patterns in relative prevalence of various OC compounds appear to be quite consistent among various marine mammal species in the Arctic. PCB and DDT concentrations in Svalbard's white whales are below the levels that are thought to have negative effects on reproduction or the immune system. 相似文献
10.
Analyses of structurally modified quasi‐solid‐state electrolytes using electrochemical impedance spectroscopy for dye‐sensitized solar cells 下载免费PDF全文
Seok‐Jun Seo Andreas Hinsch Welmoed Veurman Henning Brandt Moon‐Sung Kang Sung‐Hee Shin Seung‐Hyeon Moon 《应用聚合物科学杂志》2014,131(1)
Electrochemical properties of structurally modified quasi‐solid‐state electrolytes were examined using porous substrates (PSs). The PS was prepared into two categories by a phase inversion method with a brominated poly(phenylene oxide) (BPPO): the sponge and finger types. Effects of the humidification and cosolvent compositions on the morphology of the PS were analyzed by scanning electron microscopy. In all cases of the PSs, a higher VOC was observed of about 0.1 V than that of a liquid electrolyte owing to a suppressed back electron charge transfer. In addition, the PS prepared by the polymer solution of 1 : 4 : 1 (BPPO : N‐methyl‐2‐pyrrolidone : butyl alcohol) with the humidification process showed better photovoltaic properties in terms of the current density and conversion efficiency owing to the appropriate combinations of pore size, tortuosity, and interconnectivity. Effects of the pore structures were intensively examined using electrochemical impedance spectroscopy. The impedance results revealed that large pores at the surface layers are advantageous for a lower RS and RTiO2. Meanwhile, the straight inner structure is beneficial for the facile I?/I3? diffusion, thus lowering RPt. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39739. 相似文献