961 resultados para ISO 12647-2
Resumo:
Tese de mestrado integrado em Engenharia da Energia e do Ambiente, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016
Resumo:
Panktonic foraminiferal tests of the spinose species Orbulina universa, of the non-spinose Globorotalia tumida-menardii complex, and of a mixed species assemblage (grain size fraction 200-400 µm) were isolated from Sierra Leone Rise core GIK13519-2 and analyzed for free, total, and bound (by difference) amino acids to study the isoleucine epimerization mechanism in fossil foraminiferal tests and to define empirical calibration curves for dating deep-sea sediments over the past 900,000 years. Total isoleucine epimerization curves typically separate into three "linear" segments of decreasing apparents rates with increasing time and exhibit a pronounced "species effect". The degree of epimerization attained at time is considerably lower in O. universa than in G. tumida-menardii while the mixed species results scatter between the limits delineated by the two monospecific curves. Total allo/iso ratios are closely related to the proportion of free to total isoleucine accumulating in the tests indicating that the rate of hydrolysis of matrix proteins and peptides controls the overall epimerization reaction. The results are consistent with experimental evidenve where upon isoleucine epimerizes at a rapid rate in terminal positions but at slow rates in interior positions as well as in the free state. Notwithstanding free isoleucine exhibits the highest degree of epimerized terminal isoleucine. Species-specific hydrolysis and epimerization rates are maintained until about 50 % of bound isoleucine have been hydrolyzed to the free state corresponding to a total allo/iso ratio of about 0.5. Remaining peptide units appear to be more resistent against hydrolysis and separate species then show the same apparent epimerization rate dominantly controlled by the slow conversion rate in the free state until equilibrium is achieved in Miocene samples under deep-ocean temperature conditions. The degree of epimerization attained at comparable time in separate species will, however, remain different due to different initial rates of hydrolysis.
Resumo:
The GH72-2 shipborne survey was carried out in the northwest Pacific during 31 days under the 'Basic investigations for exploration of deep sea mineral resources' program. The sediments encountered could be classified as follows: 1) Most of the brown clays occur on the abyssal plain of the basins at depth over 4500m. 2) Calcareous oozes are predominant at the top, slope and foot of seamounts and guyots. 3) Terrigeneous sediments are distributed near islands. The concentrated zone of ferromanganese nodules was located in the Magellan seamounts area. However, the metal contents in Mn, Cu, Ni and Co for these nodules are relatively poor, and these ferromanganese deposits occur at a depth over 5000m. It is interesting to note that the shape of the nodules is sometimes nearly spherical, and that the chemical composition of the nodules is characterized by the low ratio Mn/Fe and Co/Ni.
Resumo:
This research aimed to identify any common factors that have enabled and/or motivated SMEs to successfully implement ISO 14001 whilst the majority have not. It also identified what challenges and barriers SMEs face in doing so and how some have overcome these. The existing literature suggests that the majority of SMEs perceive their environmental impacts to be proportional to their size; have a poor understanding of environmental issues; have a poor awareness of environmental regulations; do that have the necessary expertise or leadership to address environmental issues and that SMEs with an environmental management system such as ISO 14001 are very much the minority. The main factors that influenced whether an SME had implemented ISO 14001 were: competitive advantage, regulatory compliance, supply chain pressures, leadership, expertise, resources and external support. This research used qualitative analysis of interviews with managers and directors from 8 SMEs with ISO 14001 and 4 without. All of the SMEs were based in the West Midlands or Staffordshire. Interviews were also conducted with 3 organisations offering support to businesses on environmental issues and with 1 large business who was engaging their suppliers (which included SMEs within this sample) on environmental issues. The research found that there were four main factors that enabled or motivated the SMEs to implement ISO 14001, these were: leadership, supply chain pressures, external support and SMEs' history and experience of accredited management systems. The main challenges that these business had to overcome and that prevented the other SMEs from achieving ISO 14001 were: achieving regulatory compliance, perceived financial cost, lack of perceived competitive advantage, access to relevant and affordable support and for those SMEs without ISO 14001 there was very little perceived external pressure or need for them to do so.