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1.
To help in clarifying the relationship between the time lag and attenuation of nitrogen (N) loads generated in agricultural catchments, long-term trends in activities that generate N loads and in environmental N loads were estimated in catchments in Japan and Korea dominated by non-point-source emissions. Our approach used statistical data and geographical information system software to analyze pollutant loads. The method was successful in both countries because of the availability of well-developed statistics, geographical information, and weather and water quality monitoring systems, and the accumulation of research data concerning the generation of N loads and the fate of N in soils. Comparison of environmental loads with the loads observed in river water at the outlet of each catchment revealed that: (1) the effect of changes in the environmental load in a catchment appeared almost immediately in the river water quality in Korea, but did not appear clearly even 10 years later in Japan; and (2) the strength of the attenuation appeared to be much lower in Korea than in Japan. These findings suggest that regional characteristics play important roles in the sensitivity of water quality to load-generating activities. 相似文献
2.
North American workers usually stand while working, and prolonged standing is associated with discomfort and cardiovascular problems. Since prolonged sitting is also associated with health problems, and standing postures differ as to mobility and access to seating, it is desirable to identify an optimal mix of postures. As a step towards this identification, it is desirable to develop indicators of potential health effects that respond to changes in work requirements. We observed 65 subjects who usually stood at work, in four types of workplaces. Pressure-pain threshold (PPT) recorded on the plantar surface was used as an indicator of discomfort and arterial blood pressure was used as an indicator of cardiovascular effects. PPT after work was significantly lower than that before work. Sitting for even a small part of the day appeared to be protective. The effects of static vs. dynamic work on PPT and arterial blood pressure may differ. 相似文献
3.
Madekurozwa MC Chabvepi TS Matema S Teerds KJ 《Reproduction (Cambridge, England)》2002,123(5):735-742
The immunohistochemical localization of the LH receptor and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) was studied in the testis of the juvenile ostrich (Stuthio camelus) throughout a 1 year period. Spermatogenic activity of juvenile birds changed throughout the year, as has been reported previously for sexually mature birds. During the active stage of the testicular cycle, from September to January, spermatogenesis progressed up to the stage of formation of spermatozoa, although spermatozoa could not be detected in the epididymis. Leydig cells stained intensely with antibodies against the LH receptor and 3beta-HSD during the quiescent, recrudescent and active phases of the testicular cycle. During the regressive phase, there was a slight decrease in immunostaining for 3beta-HSD in these cells. These results indicate that Leydig cells in the testis of the juvenile ostrich are able to respond to LH and are capable of steroid synthesis. Furthermore, in juvenile (prepubertal) ostriches, spermatogeneic activity can be observed and, as in mature birds, spermatogenesis undergoes seasonal changes. 相似文献
4.
PC12 cells were used to examine the in vitro antioxidative and anti-inflammatory effects of oleanolic acid (OA) and ursolic acid (UA). PC12 cells were pretreated with OA or UA at 20 and 40 microM and followed by exposure of hydrogen peroxide (H(2)O(2)) or 1-methyl-4-phenylpyridinium ion (MPP(+)) to induce cell injury. Results showed that H(2)O(2)- or MPP(+)-treatment significantly decreased cell viability and increased lactate dehydrogenase (LDH) release (P < 0.05). The pretreatment from OA or UA significantly and concentration-dependently reduced subsequent H(2)O(2)- or MPP(+)-induced cell death and LDH release (P < 0.05). Either H(2)O(2)- or MPP(+)-treatment significantly increased malonyldialdehyde (MDA) formation, decreased glutathione (GSH) content, and diminished glutathione peroxidase (GPX), catalase, and superoxide dismutase (SOD) activities (P < 0.05). The pretreatment from OA or UA significantly retained GSH, and reversed H(2)O(2)- and MPP(+)-induced impairment in catalase and SOD activities (P < 0.05), and decreased MDA formation (P < 0.05). Either H(2)O(2)- or MPP(+)-treatment significantly elevated interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha levels (P < 0.05). The pretreatments from OA or UA significantly attenuated subsequent H(2)O(2)- or MPP(+)-induced release of IL-6 and TNF-alpha (P < 0.05). Based on the observed antioxidative and anti-inflammatory activities from OA and UA, these 2 compounds were potent agents against neurodegenerative disorder. 相似文献
5.
Isolation of Lysozyme from Hen Egg Albumen by Alcohol-Insoluble Cross-Linked Pea Pod Solid Ion-Exchange Chromatography 总被引:2,自引:0,他引:2
ABSTRACT: Albumen from hen eggs was diluted 3-fold with 0.05 M NaCl solution at pH 4.0 and was further treated with 30% ethanol for 8 h. The supernatant (77900 U/mg protein) thus obtained was further diluted (2.5-fold) with distilled water and its pH value was adjusted to 8.0 before being subjected to alcohol-insoluble cross-linked pea pod solid (AICLPPS) ion-exchange chromatography for lysozyme isolation. Results showed that AI-CLPPS ion-exchange chromatography increased the purification to 68-fold with a 72% lysozyme recovery from the starting albumen. 相似文献
6.
An experimental on-site observatory of urban pollutant loads in combined sewers was created in the centre of Paris to quantify and characterise the dry and wet weather flow in relation to spatial scale. Eight rainfall events were studied from April 2003 to May 2004. Samples were analysed for suspended solids, organic matter, nitrogen and heavy metals. Results confirm the extent of wet weather pollution. They have shown the relative homogeneity of SS and organic matter characteristics from one urban catchment area to another. Two groups of heavy metals were identified. The first one concerns Cu, which has a higher concentration in wet weather flow (WWF) than in dry weather flow (DWF), and runoff. The second includes Cd, Pb and Zn, where higher concentrations were measured in urban runoff than in WWF and DWF. A first evaluation of contribution of wastewater, urban runoff and sewer deposit erosion sources to wet weather pollution was established and has highlighted the contribution of wastewater and sewer deposits to this pollution. However, it has shown that sewer deposit erosion remains an important source of wet weather pollution at different spatial scales. 相似文献
7.
Several studies have indicated that only one cleavage site (Ala-1/Val+1) is involved in the release of mature TNF from human pro-TNF, whereas others have suggested that the linking sequence (residues -20 to -1) may be important. We previously demonstrated that a pro-TNF deletion mutant, delta -20- -1, was able to form a trimeric structure and mediate TNF cytotoxicity in a juxtacrine fashion without releasing mature TNF. We constructed seven mutants with smaller deletions within this region. Three 15-residue deletion mutants, delta -20- -6, delta -15- -1 and delta -20- -16, -10- -1, were noncleavable, although able to form a trimer and to mediate cytotoxicity through cell-to-cell contact. Three five- or ten-residue deletion mutants, delta -20- -16, delta -10- -1, and delta -5-, -1, behaved like the wild-type TNF; all formed a trimer and released mature TNF. These results suggested that in pro-TNF (1) the number of residues between the base of the trimer and the plasma membrane determines accessibility of the cleavage site to the pro-TNF processing enzyme(s) since small deletions did not block cleavage whereas large ones did regardless of the presence of the native cleavage site (-1/+1), (2) the native cleavage site is not sufficient for releasing mature TNF because mutant delta -20- -6, in which the native cleavage site was intact, was noncleavable, and (3) alternative cleavage site(s) may exist since mutants delta -10- -1 and delta -5- -1, which lack the native cleavage site, were cleavable. 相似文献
8.
Heinrich U Koop U Leneveu-Duchemin MC Osterrieder K Bielfeldt S Chkarnat C Degwert J Häntschel D Jaspers S Nissen HP Rohr M Schneider G Tronnier H 《International journal of cosmetic science》2003,25(1-2):45-53
A multicentre study for measuring skin hydration with 349 volunteers was carried out in six different laboratories. The purpose of the study was to investigate physical-, physiological- and product-dependent parameters of three test emulsions (base, base + moisturizer and base + moisturizer + lipids) in a double-blind study. A comparison between analogous and digital sensor technology of the Corneometer CM825 was examined. Here, a clear relationship between both sensor types could be highlighted. A vital point of the study was the division of the test subjects according to their skin type. To get more objective limits for three different skin types - very dry, dry and normal skin - visual expert evaluation, self-assessment and hydration measurements were analysed by means of statistical methods. The moisture-related skin types were determined as follows: very dry skin was characterized with corneometer units below 30, dry skin between 30 and 40 and normal skin higher than 40 a.u. (arbitrary units). The efficacy of the three test emulsions was examined in relation to the mentioned skin types. Analysing the measured data of all test centres, a clear dependency of skin physiology (skin type) and product efficacy became evident. The drier the skin, the higher the increase of hydration. The product performance of the three test emulsions compared to the untreated control resulted in a significant increase of skin hydration in all measuring centres. The evaluation of a product ranking showed a good differentiation between the basic emulsion and the two other products. An increase of efficacy by adding lipids could be observed in four of six centres. The important influence of the skin type of the volunteers on the degree of product performance, as demonstrated in this study, should be especially considered when drawing up guidelines for efficacy testing. 相似文献
9.
Contributions of wastewater, runoff and sewer deposit erosion to wet weather pollutant loads in combined sewer systems 总被引:4,自引:0,他引:4
An observatory of urban pollutants was created in Paris for the purpose of assessing the dynamics of wastewater and wet weather flow (WW and WWF) pollutant loads within combined sewers. This observatory is composed of six urban catchments, covering land areas ranging in size from 42 ha to 2581 ha. For a wide array of parameters including total suspended solids (TSS), chemical and biochemical oxygen demand (COD and BOD5), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), heavy metals (Cu and Zn) and polycyclic aromatic hydrocarbons (PAHs), this article is intended to evaluate the contributions of wastewater, runoff and in-sewer processes to WWF pollutant loads through the use of an entry–exit mass balance approach. To achieve this objective, a total of 16 rain events were sampled on these sites between May 2003 and February 2006. This study has confirmed that at the considered catchment scale (i.e. from 42 ha to 2581 ha) the production and transfer processes associated with WWF pollutant loads do not vary with basin scale. Entry–exit chemical mass balances over all catchments and for a large number of rain events indicate that wastewater constitutes the main source of organic and nitrogenous pollution, while runoff is the predominant source of Zn. For Cu, PAHs and TSS, the calculation underscores the major role played by in-sewer processes, specifically by sediment erosion, as a source of WWF pollution. A significant loss of dissolved metals was also observed during their transfer within the sewer network, likely as a consequence of the adsorption of dissolved metals on TSS and/or on sewer deposits. Moreover, the nature of eroded particles was examined and compared to the various sewer deposits. This comparison has highlighted that such particles exhibit similar organic and PAH contents to those measured in the organic layer, thus suggesting that the deposit eroded during a wet weather period is organic and of a nature comparable to the organic layer. Despite the extent of initial field investigations, no organic deposit was observed to be present on sewer lines within the catchments, which implies that this organic deposit is probably present in another form or to be found elsewhere in the main trunks. 相似文献
10.
The radiolytic degradation of di-2-ethylhexyl-isobutyramide (DEHiBA) was examined by subjecting the compound to gamma irradiation, measuring the remaining concentration of the intact compound, identifying the degradation products, and measuring uranium distribution ratios. The combined effects of radiation dose, contact with aqueous solutions of HNO3, and aeration were also examined. The DEHiBA displayed significant stability at doses up to 1000 kGy, undergoing a slow exponential concentration decrease that was accompanied by the appearance of multiple degradation products. The most abundant compounds that were formed by radiolysis resulted from cleavage of the Ccarbonyl–N and Cethylhexyl–N bonds, generating di-ethylhexylamine and mono-ethylhexyl-isobutyramide. Acid contact did alter the radiolytic pathways, with acid favoring cleavage of the Ccarbonyl-N bond, while a more diverse array of compounds was formed in the absence of acid. Pulsed radiolysis experiments were also conducted, in which picosecond bursts of energetic electrons were used to irradiate solutions of dodecane containing DEHiBA; formation of the dodecane radical cation was implicated, which serially reacted with DEHiBA to form a radical or radical cation species intermediate in the formation of the observed products. The slow degradation kinetics suggests that DEHiBA possesses good potential for selective extraction of uranium in fuel cycle extraction operations. 相似文献