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221.
Regenerative phenomena reproduce developmental processes in adult organisms and are regulated by neuro-endocrine mechanisms. They can therefore provide sensitive tests for monitoring the effects of exposure to endocrine disrupter contaminants (EDs) which can be bioaccumulated by the organisms causing dysfunctions in steroid hormone metabolism and activities and affecting reproduction and development. Echinoderms are prime candidates for this new ecotoxicological approach, since (1) they offer unique models to study physiological regenerative processes and (2) in echinoderms vertebrate-type steroids can be synthesized and used as terminal hormones along the neuro-endocrine cascades regulating reproductive, growth and developmental processes. We are currently exploring the effects on the regenerative potential of echinoderms of different classes of compounds that are well known to have ED activity. The present paper focuses on the possible effects of well-known compounds with suspected androgenic activity such as TPT-Cl (Triphenyltin-chloride) and Fenarimol [(±)-2,4-dichloro-α-(pyrimidin-5-yl) benzhydryl alcohol]. The selected test-species is the crinoid Antedon mediterranea, a tractable and sensitive benthic filter-feeding species which represents a valuable experimental model for investigation on the regenerative process from the macroscopic to the molecular level. The present investigation employs an integrated approach which combines exposure experiments and biological analysis utilizing microscopy, immunocytochemistry and biochemistry. The experiments were carried out on experimentally induced arm regenerations in semistatic controlled conditions with exposure concentrations comparable to those of moderately polluted coastal zones. The bulk of results obtained so far provide indications of significant sublethal effects from exposure to TPT-Cl and Fenarimol and mechanisms of toxicity related to developmental physiology, which are associated with variations in steroid levels in the animal tissues. The results indicate that these two substances (1) affect growth and development by interfering with the same basic cellular mechanisms of regeneration, such as cell proliferation, migration and differentiation/dedifferentiation, which are possibly controlled by steroid hormones; and (2) can induce a number of significant modifications in the timing, modalities and pattern of arm regeneration, which may involve the activation of cell mechanisms related to steroid synthesis/metabolism. Physical and Chemical Impacts on Marine Organisms, a Bilateral Seminar Italy-Japan held in November 2004  相似文献   
222.
Terrain in natural areas is never homogeneous: there may be a variety of vegetation types and patches of vegetated and unvegetated areas which can modify the mesoscale atmospheric flow. Moreover, horizontal thermal inhomogeneities in the planetary boundary layer are a well known source of mesoscale circulation systems such as land and sea breezes, mountain-valley winds, and urban heat island circulations. Since those phenomena are not resolved in regional scale numerical models, therefore an analytic procedure able to evaluate the relative importance of mesoscale and turbulent heat fluxes associated with surface thermal heterogeneities is of crucial importance in the optic of developing a parameterization of mesoscale effects generated by these heterogeneities for use in larger scale models. In the present paper we analyze how small a horizontal variation in surface heating can be and still produce a significant mesoscale circulation, how the heat and momentum fluxes associated to mesoscale flows can penetrate deeply into the mid-troposphere, and how they modify tropospheric relevant climate parameters, such as the atmospheric static stability. In addition, we evaluate the terms of the pressure gradient force, nonlinear and linear, non-hydrostatic and hydrostatic, as function of time and space scales of the mesoscale flow. The present paper is mainly a review of analytical results, the numerical comparison and verification using RAMS is in progress.  相似文献   
223.
Biodegradability under composting conditions is assessed by test methods, such as ASTM D 5338-92, based on the measurement of CO2 released by test materials when mixed with mature compost and maintained in a controlled composting environment. However, in real composting, biodegradation occurs in fresh waste. To clarify this point, the biodegradation of paper and of a starch-based biodegradable thermoplastic material, Mater-Bi ZI01U, was followed by measuring the weight loss of samples introduced either into a mature compost or into a synthetic waste. The weight loss in mature compost was higher at the beginning but tended to decrease; in synthetic waste a first lag phase was followed by an exponential phase. Complete degradation of paper was noticed simultaneously in the two substrates (after 25 days). The bulkier Mater-Bi samples were fully degraded after 20 days in fresh waste, but after 45 days in mature compost. Therefore, the test methods using mature compost as a substrate can possibly underestimate the biodegradation rate occurring in fresh waste, i.e., in real composting plants, and have to be considered as conservative test methods. The test procedure described in this paper seems very suitable as a screening method to verify the compostability of plastic materials in a composting environment.  相似文献   
224.
Mellini M  Riccobono F 《Chemosphere》2005,60(9):1246-1252
A depleted-uranium penetrator, shot in 1999 at Djakovica, Western Kosovo, and there collected in June 2001, shows evident alteration processes, perceivable as black and yellow coatings. XRD indicates that the black coating mostly consists of uraninite, UO2, with possible presence of other more oxidized uranium forms, such as U3O8. The yellow material is mostly amorphous, with variable weak diffraction lines, due to minor embedded uraninite grains, or possibly to schoepite, UO3 x 2H2O. SEM-EDS reveals only uranium. Whereas uraninite does not show any crystal shape, the yellow material recrystallizes to flattened pseudo-hexagonal prisms, approximately 2-10 microm wide and 1-4 microm long. Raman spectra of the yellow material have peaks at 3474 and 3222 cm(-1), indicative for OH groups, plus at 812 and 744 cm(-1), indicative for UO2(2+) uranyl ions. Based on the different data, the yellow material covering the depleted-uranium dart is an oxidized corrosion product, containing uranyl ions and hydroxyls and/or water molecules, akin to schoepite. Therefore, the Djakovica dart shows evident oxidation and leaching processes, progressively releasing mobile uranium forms. As uranium will be progressively dispersed far from the impact sites, at a rate controlled by the presence of effective fixing mechanisms, we feel necessary to maintain long term geochemical control of water pollution within the battlefield surroundings.  相似文献   
225.
In this study, long-term aerosol particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a condensation particle counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm(-3) and 20,000 cm(-3), whereas the summer min is approximately 5000-6000 cm(-3). In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4-10. The winter maximum in both Rome and Barcelona is close to 100,000 cm(-3), whereas the summer minimum is > 10,000 cm(-3). During the weekdays the maximum of the hourly average concentrations in all of the cities is detected during the morning hours between 7 and 10 a.m. The evening maxima were present in Barcelona, Rome, and Augsburg, but these were not as pronounced as the morning ones. The daily maxima in Helsinki and Stockholm are close or even lower than the daily minima in the more polluted cities. The concentrations between these two groups of cities are different with a factor of about five during the whole day. The study pointed out the influence of the selection of the measurement site and the configuration of the sampling line on the observed concentrations.  相似文献   
226.
The present investigation was carried out on the bluefin tuna (Thunnus thynnus) collected during the month of April 2003 from the Straits of Messina. The aim of this study is to determine heavy metal levels (Cd, Cu, Hg, Mn, Pb and Zn) in liver and muscle tissues of 14 Thunnus thynnus of different age and sex and to investigate the relationships between fish sex and size (length and weight and metal concentrations in the tissues. The concentrations of the various metals were determined by a Varian atomic absorption spectroscopy instrument. The results showsignificant variations (p < 0.01) for Hg and Zn concentrations in muscle than in liver samples. Concentrations of Cd and Pb are below the instrumental detection limits in almost all muscle samples. Levels of Hg (3.03 + 0.55 μg/g) are above the MRLs only in muscle (1μg/g) establishing toxicological risks for the consumer. Regression analysis shows a negative correlation between mercury level and weight and length in samples from both female and male. No significant difference between mean heavy metals concentrations and male or female tuna is seen. For greater food safety, it would be advisable to reduce the mercury intake by selecting safer fish, species and size and by the avoidance of tuna fish consumption by pregnant women, young children and old people, who are more sensitive to mercury exposure.  相似文献   
227.
Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants and is extensively used in electronic equipment, furniture, plastics, and textiles. It is frequently detected in water, soil, air, and organisms, including humans, and has raised concerns in the scientific community regarding its potential adverse health effects. Human exposure to TBBPA is mainly via diet, respiration, and skin contact. Various in vivo and in vitro studies based on animal and cell models have demonstrated that TBBPA can induce multifaceted effects in cells and animals, and potentially exert hepatic, renal, neural, cardiac, and reproductive toxicities. Nevertheless, other reports have claimed that TBBPA might be a safe chemical. In this review, we re-evaluated most of the published TBBPA toxicological assessments with the goal of reaching a conclusion about its potential toxicity. We concluded that, although low TBBPA exposure levels and rapid metabolism in humans may signify that TBBPA is a safe chemical for the general population, particular attention should be paid to the potential effects of TBBPA on early developmental stages.  相似文献   
228.
Air pollution has been linked to many health issues,including skin conditions,especially in children.Among all the atmospheric pollutants,ultrafine particles have been deemed very dangerous since they can readily penetrate the lungs and skin,and be absorbed into the bloodstream.Here,we employed a human embryonic stem cell(h ESC)-based differentiation system towards keratinocytes,to test the effects of ultrafine carbon particles,which mimic ambient ultrafine particles,at environment related concentrations.We found that10 ng/mL to 10 μg/mL ultrafine carbon particles down-regulated the expression of the pluripotency marker SOX2 in h ESCs.Moreover,1 μg/mL to 10 μg/mL carbon particle treatments disrupted the keratinocyte differentiation,and up-regulated inflammationand psoriasis-related genes,such as IL-1β,IL-6,CXCL1,CXCL2,CXCL3,CCL20,CXCL8,and S100 A7 and S100 A9,respectively.Overall,our results provide a new insight into the potential developmental toxicity of atmospheric ultrafine particles.  相似文献   
229.
Soil erosion and associated off-site environmental impacts have attracted increasing attention in recent decades, and there is a growing need for reliable information on rates of soil loss. The potential for using 137Cs fallout to quantify rates and patterns of soil redistribution over medium-term timescales (ca. 45 years) has been successfully demonstrated in a wide range of environments around the world. The similar behaviour of fallout 210Pb in soils offers potential for its use as an alternative to 137Cs, in areas where 137Cs inventories are low or are complicated by additional fallout from the Chernobyl accident. There have, however, to date been few attempts to validate the use of fallout 210Pb measurements for assessing erosion rates. This paper reports an attempt to explore the use of fallout 210Pb to estimate rates of water-induced soil erosion on uncultivated land. It focuses on three small forest/rangeland catchments located in Calabria, southern Italy, for which measurements of sediment output are available. Comparison of the estimates of net soil loss from the catchments derived from 210Pb measurements with the measured sediment output, confirmed the validity of the 210Pb approach. The soil redistribution rates estimated using 210Pb measurements were also consistent with equivalent estimates obtained for the same study catchments using 137Cs measurements.  相似文献   
230.
This paper analyzes the practices adopted and difficulties experienced by Small and Medium-sized Enterprises (SMEs) to transfer socially responsible behaviors to suppliers that operate in developing countries. In particular, a multiple case study was conducted on five Italian socially responsible SMEs. It was found that companies use different strategies as well as diverse management systems and tools to address Corporate Social Responsibility (CSR) issues along their supply chains (SCs). The paper is innovative mainly since few are the existing studies that investigate the CSR practices adopted by SMEs in the SC. Furthermore, it is argued that our research can be helpful to SME managers willing to deal with CSR issues along their SCs, especially when developing countries are involved.  相似文献   
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