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151.
In this project concrete mixtures were prepared that were characterized by low ductility due to desiccation by using debris from building demolition, which after a suitable treatment was used as aggregate for partial replacement of natural aggregates. The recycled aggregate used came from a recycling plant, in which rubble from building demolition was selected, crushed, cleaned, sieved, and graded. Such aggregates are known to be more porous as indicated by the Saturated Surface Dry (SSD) moisture content. The recycled concrete used as aggregates were added to the concrete mixture in order to study their influence on the fresh and hardened concrete properties. They were added either after water pre-soaking or in dry condition, in order to evaluate the influence of moisture in aggregates on the performance of concrete containing recycled aggregate. In particular, the effect of internal curing, due to the use of such aggregates, was studied. Concrete behavior due to desiccation under dehydration was studied by means of both drying shrinkage test and German angle test, through which shrinkage under the restrained condition of early age concrete can be evaluated. 相似文献
152.
Feliu López-i-Gelats J. David Tàbara 《Journal of Agricultural and Environmental Ethics》2010,23(4):331-344
The agro-food domain in Europe is characterized by the appearance of recurrent unwanted surprises. These events, although
causing obvious physical consequences, in essence depart from the expectations of the society. We argue that this unstable
situation is best understood as an identity crisis of agriculture rather than as a contingent crisis of a specific economic
sector. Thus the present agro-food crisis is in fact a crisis of identity. This is clearly reflected by the cohabitation within
the agro-food policy domain of different, often contradictory, policy discourses, namely: free tradism, multifunctionality,
and agroecology. All of them try to impose their particular visions. All of them struggle to issue the policy measures they
conceive as appropriate. 相似文献
153.
Biological aspects of the only two epi-/mesopelagic pasiphaeid species distributed along the continental marginof the north-western Mediterranean Sea were studied over the period 1991-1994. The annual reproductive cycle, reproductive output, sex and size distributions by depth (near-bottom distribution), and growth were analysed using 4156 specimens of Pasiphaea sivado (Risso, 1816) and 5491 specimens of P. multidentata Esmark, 1866. The reproductive cycle in the shallower-dwelling species, P. sivado, was nearly continuous, in contrast to the reproductive cycle in P. multidentata, which was markedly seasonal in nature. Both species exhibited similar size and population structure patterns with depth, with individual size increasing along the bottom depth gradient. The shallower-dwelling species had a significantly higher reproductive output level, in terms of the relative number of eggs, than the deeper-dwelling species. Biological trends for each of the species have been compared. The comparative results for these two congeneric species revealed that the biological parameters analysed were closely linked to their population structure. The slight differences in the depth range inhabited by each species have been considered the main environmental factor affecting the life histories of these two species. The data presented supported the hypothesis that depth exerted an important influence on the biological patterns of deep-water species, with the seasonality of reproductive processes increasing in deeper-dwelling species. 相似文献
154.
深基坑施工过程中的风险因素具有模糊性与随机性的特点,基于此提出一种熵权二维云模型的风险评价方法。从环境因素、管理因素和施工因素3个方面进行危险源辨识,确定深基坑施工风险评价指标体系,并应用熵权法对评价指标进行加权处理;将风险概率和风险后果作为二维云模型的基础变量,同时提出风险云相近度的计算方法以确定风险等级。应用上述方法对南宁轨道交通3号线青秀山站明挖站厅基坑的施工过程进行了风险评价,得出该施工过程的风险需采取一定控制措施方可接受,与实际情况相符,表明基于熵权二维云模型的风险评价方法合理可行。 相似文献
155.
156.
M. Sarà 《Marine Biology》1971,11(3):214-221
The association between two species of the genus Aphanocapsa (Cyanophyceae) and the sponge Ircinia variabilis has been studied by electron microscopy. A. feldmanni is localized in the mesohyl or inside the cells of the sponge, while the larger A. raspaigellae is located only in an extracellular position inside cavities of the mesohyl. Both algae differ from other symbiotic Cyanophyceae in having a normal cell wall. They are able to reproduce in symbiotic condition, but also undergo, in their various extracellular and intracellular positions, a massive process of disintegration. A large amount of algal material is dispersed in the sponge tissues, which is a confirmation, at the ultrastructural level, of trophic relationships in the symbiosis Aphanocapsa-Ircinia. 相似文献
157.
Porta M Grimalt JO Jariod M Ruiz L Marco E López T Malats N Puigdomènech E Zumeta E;PANKRAS II Study Group 《Environment international》2007,33(7):946-954
We aimed to analyse the influence of cholesterol and triglycerides, and of tobacco, coffee and alcohol consumption upon correlations between serum concentrations of organochlorine compounds (OCs) in patients with exocrine pancreatic cancer (EPC). Incident cases of EPC diagnosed in eastern Spain were prospectively identified (N=144). OCs were analysed by high-resolution gas chromatography with electron-capture detection. A strong correlation was observed between hexachlorobenzene (HCB) and beta-hexachlorocyclohexane (beta-HCH) (Spearman's rho=0.758). beta-HCH showed rho>0.4 with p,p'-DDT, p,p'-DDE, PCB138 and PCB153 (all p<0.001). Some correlations among compounds were slightly affected by tobacco, coffee or alcohol consumption. We observed a striking diversity of correlation patterns by strata of cholesterol and triglycerides. Most correlations were higher in the lowest category of triglycerides than in the lowest category of cholesterol. Most coefficients above 0.7 were seen in the lowest category of triglycerides (e.g., OC pairs p,p'-DDT and HCB, p,p'-DDT and beta-HCH, p,p'-DDE and beta-HCH, or HCB and beta-HCH). Correlations among OCs may be stronger when concentrations of triglycerides are low than when they are high. This is compatible with a dilution in the early phases of cancer and with a concentration effect as triglycerides become lower in the advanced phases of the disease. 相似文献
158.
Spatial and temporal changes in the biochemical composition of particulate organic matter in a semi-enclosed marine system (Stagnone di Marsala, Mediterranean Sea) were studied, on a monthly basis, from January to December 1994, in order to assess nutritional value of suspended particles for benthic suspension feeders. According to previous findings, the study site displayed a strong oligotrophy. Chlorophyll-a accounted for a very low fraction of the total suspended matter pool (0.1%), whereas at least 75% of POC was of detrital/heterotrophic origin. POC: PON ratio values indicate that bacterioplankton biomass accounted for a significant fraction of the total POC pool, displaying values comparable to those of the phytoplankton biomass (phytoplankton to bacterial biomass ratio was about (1). Temporal and spatial changes in the biochemical composition of particulate organic matter were rather limited and related to its sources, the main of which is represented by detrital particles released by the Posidonia oceanica (L.) beds. the comparison between our results and those encountered in other coastal lagoons indicates that the low abundance of suspension-feeding organisms observed in the study area is related to the “quality depression” of particles due to the dilution of high quality compounds (i.e., biopolymeric carbon) in a largely inorganic matrix. This result leads us to conclude that, to reach the same amount of high quality particulate food, a suspension feeder mollusc in the Marsala lagoon would need to filter a sea water volume around 3 times higher than in other Mediterranean coastal lagoons. 相似文献
159.
Valeria Sodano 《Environmental Chemistry Letters》2018,16(1):5-10
Over the last twenty years, nanotechnology has slowly entered the agrifood sector. Meanwhile, testimonies of possible risks associated with the new nanomaterials were collected. This article investigates the reasons for the delay in regulatory intervention with respect to nanotechnology in the agrifood sector. Findings show that the unregulated introduction of nanomaterials into the food system is the result of the current neoliberal food policy, and the power struggles that govern the economic, social and political dynamics of the global supply chain. It is therefore necessary to put at the center of the regulatory debate the question concerning technology. Specifically, how technology influences power relationships within society should be studied. In other words, attention should be shifted from efficiency issues to power issues. New technologies should be assessed from a political perspective rather than an economic or ethical perspective. 相似文献
160.
Ivon Cuadros-Casanova Andrea Cristiano Dino Biancolini Marta Cimatti Andrea Antonio Sessa Valeria Yeraldin Mendez Angarita Chiara Dragonetti Michela Pacifici Carlo Rondinini Moreno Di Marco 《Conservation biology》2023,37(3):e14052
The Common Agricultural Policy (CAP) is the European Union's main instrument for agricultural planning, with a new reform approved for 2023–2027. The CAP intends to align with the European Green Deal (EGD), a set of policy initiatives underpinning sustainable development and climate neutrality in the European Union (EU), but several flaws cast doubts about the compatibility of the objectives of these 2 policies. We reviewed recent literature on the potential of CAP environmental objectives for integration with the EGD: protection of biodiversity, climate change mitigation and adaptation, and sustainable management of natural resources. The CAP lacks appropriate planning measures, furthering instead risks to biodiversity and ecosystem services driven by landscape and biotic homogenization. Funding allocation mechanisms are not tailored to mitigate agricultural emissions, decreasing the efficiency of climate mitigation actions. The legislation subsidies farmers making extensive use of synthetic inputs without adequately supporting organic production, hindering the transition toward sustainable practices. We recommend proper control mechanisms be introduced in CAP Strategic Plans from each member state to ensure the EU is set on a sustainable production and consumption path. These include proportional assignment of funds to each CAP objective, quantitative targets to set goals and evidence-based interventions, and relevant indicators to facilitate effective monitoring of environmental performance. Both the CAP and the EGD should maintain ambitious environmental commitments in the face of crisis to avoid further degradation of the natural resources on which production systems stand. 相似文献