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551.
Romeu Casarano Denise F. S. Petri Michael Jaffe Luiz H. Catalani 《Journal of Polymers and the Environment》2010,18(1):33-44
A new aliphatic block copolyester was synthesized in bulk from transesterification techniques between poly((R)-3-hydroxybutyrate)
(PHB) and poly(isosorbide succinate) (PIS). Additionally, other two block copolyesters were synthesized in bulk either from
transesterification reactions involving PHB and poly(l-lactide) (PLLA) or from ring-opening copolymerization of l-lactide and hydroxyl-terminated PHB, as result of a previous transesterification reactions with isosorbide. Two-component
blends of PHB and PIS or PLLA were also prepared as comparative systems. SEC, MALDI-TOF mass spectrometry (MALDI-TOFMS), 1H and 13C NMR spectroscopy, WAXD, solubility tests, and TG thermal analysis were used for characterization. The block copolymer structures
of the products were evidenced by MALDI-TOFMS, 13C NMR, and WAXD data. The block copolymers and the corresponding binary blends presented different solubility properties,
as revealed by solubility tests. Although the incorporation of PIS sequences into PHB main backbone did not enhance the thermal
stability of the product, it reduced its crystallinity, which could be advantageous for faster biodegradation rate. These
products, composed of PHB and PIS or PLLA sequences, are an interesting alternative in biomedical applications. 相似文献
552.
Rachana Bhatt K. C. Patel Ujjval Trivedi 《Journal of Polymers and the Environment》2010,18(2):141-147
An extracellular poly(3-hydroxybutyrate) (PHB) depolymerase produced by a thermotolerant fungal soil isolate, Aspergillus fumigatus 202, was purified and characterized. Maximum PHB depolymerase production was obtained at the end of 48 h with initial medium
pH 7.0 and 45 °C in Bushnell Haas Minerals medium containing PHB as sole source of carbon. The PHB depolymerase was purified
using size exclusion chromatography to a fold purification of 20.62 and 61.62% yield. SDS-PAGE and isoelectric focusing revealed
the molecular weight and pI of the purified enzyme as 63,744 Da and 4.2, respectively. N-terminal amino acid sequence of purified
enzyme was HAXDAYLVK. This non-glycosylated enzyme was most active at pH 9.0 and 45 °C. Purified enzyme was inactivated by
N-bromosuccinimide and dithiothreitol suggesting the involvement of tryptophan residues and disulfide bonds at its active
site. Nonionic detergents like Tween 20, Tween 80 and Triton X-100 inhibited the enzyme activity. Ions like Ca+2 and Mg+2 (5 mM) increased the enzyme activity 1.5 times. Fe+2 effectively inhibited the enzyme activity to 88% whereas Hg+2 completely inhibited the enzyme. 相似文献
553.
Bernadett Bartha Christian Huber Rudolf Harpaintner Peter Schröder 《Environmental science and pollution research international》2010,17(9):1553-1562
Purpose
Besides classical organic pollutants and pesticides, pharmaceuticals and their residues have nowadays become recognized as relevant environmental contaminants. The risks of these chemicals for aquatic ecosystems are well known, but information about the pharmaca-plant interactions and metabolic pathways is scarce. Therefore, we investigate the process of uptake of acetaminophen (N-Acetyl-4-aminophenol) by Brassica juncea, drug-induced defense responses and detoxification mechanisms in different plant parts. 相似文献554.
Ika Paul-Pont Xavier de Montaudouin Patrice Gonzalez Philippe Soudant Magalie Baudrimont 《Environmental science and pollution research international》2010,17(4):987-998
Introduction
Within the last decade, numerous studies have investigated the role of environmental history on tolerance to stress of many organisms. This study aims to assess if Manila clams Ruditapes philippinarum may react differently to cadmium exposure and trematode parasite infection (Himasthla elongata) depending on their origin and environmental history in Arcachon Bay (France). 相似文献555.
556.
According to various reports, climate change is responsible for the change in rainfall amount and pattern accompanied by the
various degrees of extreme events in Sahelian West Africa in recent years. Other reports also suggest that there has been
a “recovery” of the rainy season (Nicholson 2005). In this study, temporal characteristics of meteorological droughts in the Volta basin, a semi-arid region in West Africa,
are investigated in order to provide a guide for sustainable water resource management. For this purpose, drought intensity,
areal extent and recurrence frequency is analysed using the standardised precipitation index (SPI) for a time series between
1961 and 2005 from 52 meteorology stations across the Volta basin. Using this analysis the severity of the historical droughts
of 1961, 1970, 1983, 1992 and 2001 that occurred in the region are assessed and their intensity, areal extent and return periods
are obtained. The drought intensity is lower than −2.0 over nearly 75% of the region, meaning that a major part of the region
was under extreme drought conditions during this year. The drought of 1983/1984 has a probability of occurrence of up to 0.1
from records spanning 44 years. The areal extent of extreme drought conditions is about 90% during this drought period. 相似文献
557.
Towards institutional analysis of sustainability science: a quantitative examination of the patterns of research collaboration 总被引:2,自引:2,他引:0
This paper examines quantitatively the patterns of collaboration over geographical boundaries in the emerging field of sustainability
science by empirically analyzing the bibliometric data of scientific articles. The results indicate that an increasing number
of countries are engaged in research on sustainability, with the proportion of articles published through international collaboration
rising as well. The number of countries engaged in international collaboration on sustainability research has been increasing,
and the diversity of countries engaged in research collaboration beyond national borders is also increasing. The geographical
patterns of collaboration on sustainability show that research collaboration tends to be conducted between countries which
are geographically located closely, suggesting that communication and information exchange might be limited within the regional
clusters. The focused fields of research activities on sustainability are significantly different between countries, as each
country has its focused fields of research related to sustainability. The specialization of research activities is also observed
in international collaboration. While these patterns of international collaboration within regional clusters focusing on specific
fields could be effective in promoting the creation, transmission, and sharing of knowledge on sustainability utilizing the
already existing regional networks, they could pose a serious obstacle to collecting, exchanging, and integrating diverse
types of knowledge, especially when it is necessary to deal with problems involving large-scale complex interactions with
long-term implications, such as climate change. It would be of critical importance to establish inter-regional linkages by
devising appropriate institutional arrangements for global research collaboration on sustainability science. 相似文献
558.
Vo Thi Thanh Loc Simon R. Bush Le Xuan Sinh Nguyen Tri Khiem 《Environment, Development and Sustainability》2010,12(6):889-908
This paper investigates the structure, function and wealth distribution within the Pangasius hypophthalmus and Henicorhynchus spp./Labiobarbus spp. value chains in the Mekong Delta of Vietnam. The analysis is driven by key questions relating to the form and function
of value chains, their contribution to the livelihoods of farmers and fishers, the effectiveness of government policy and
the potential for value chain governance mechanisms, such as contracts and certification, to steer towards sustainable production.
The results indicate that actors in the high value Pangasius hypopthalmus export chain have a higher potential income, but face considerably higher economic vulnerability from global markets. Alternatively,
Henichorhychus/Labiobarbus spp. fishers are severely constrained in their ability to negotiate higher prices for their fish but appear to be less vulnerable
to economic and environmental change. The paper concludes that for value chain governance to improve the livelihoods of fishers
and farmers in both high and low value chains, new arrangements are needed that better accommodate customary institutions
and informal market relations. 相似文献
559.
Developed countries are major markets for developing country fresh produce. Demand by developed country consumers for spotless
produce has encouraged developing country consumers to rely increasingly on pesticides in producing fresh export vegetables.
However developed country pesticide standards enacted in response to reports of increased farmer and farm worker pesticide
poisoning and the food safety scandals of the 1980s and 1990s require changes in the way growers use pesticides. The EU has
especially developed stringent food safety standards relating to, among other things, pesticide usage. Under EU pesticide
standards (EU-PS) farmers are trained by their buyers on safe use of pesticides and then closely monitored under contract.
This paper looks at the impact of these standards on developing country farmers’ use of alternative pest management practices,
pesticide protective clothing and the actual usage of pesticides. It finds that compliance with EU-PS increases the use of
alternative pest management practices and protective clothing. However, EU-PS has mixed effect on the quantity of pesticides
used. The paper also finds that farmer’s education and access to information play an important role in the use of alternative
pest management practices. The paper concludes that EU-PS encourage the use of alternative pest management practices and pesticide
protective gear in production of fresh export vegetables. The findings imply that EU-PS promote environmentally-friendly methods
of production of fresh export vegetables in developing countries. 相似文献
560.
Courtney Fidler 《Environment, Development and Sustainability》2010,12(2):233-244
While the role Aboriginal people play in environmental governance programs are often underpinned by the Crown, Aboriginal
peoples are ratifying negotiated agreements with mining proponents to ensure their issues and concerns are addressed. This
paper examines Aboriginal participation in mine development to show how more inclusive social and environmental development
models can support a more sustainable development. Through two complementary processes, negotiated agreements and environmental
impact assessment, Aboriginal peoples are maximizing their benefits and minimizing the adverse impacts of a project to create
a more sustainable resource development. Case study analysis of the Galore Creek Project in northwestern British Columbia,
Canada, illustrates how environmental impact assessment and negotiated agreements can co-exist to positively contribute to
a successful mineral development, and hence operationalize sustainability within this context. 相似文献