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991.
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
992.
Ikechukwu D. Anyaogu Paul M. Ejikeme John A. Ibemesi 《Journal of Polymers and the Environment》2010,18(2):104-115
Soybean oil (SBO) was dimerized and the crude dimer acid product reacted with 1,2-phenylene diamine at 210 ± 5 °C under inert
atmosphere to obtain fatty polyamide (FPA). The FPA was used to modify a commercial alkyd resin by reacting a mixture of the
alkyd resin with 5 wt% of FPA at 120 °C for 80 min under inert atmosphere. The FTIR spectrum of the FPA modified resin showed
evidence of higher degree of H-bonding than was found for the unmodified alkyd. White gloss coatings of 15, 20, 25, and 30%
solids were formulated from the modified and unmodified resins and examined for performance with respect to: leveling, sag
resistance, drying time, pigment settling, skinning tendency and film hardness. Results showed that the unmodified alkyd coatings
exhibited good leveling but poor sag resistance at all solid contents. In contrast, FPA modified alkyd coatings combined good
leveling with high sag resistance indicating their thixotropic nature. A strong tendency to pigment settling was observed
for unmodified alkyd coatings but was not observed in the FPA modified alkyd coatings. The modified alkyd coatings showed
skinning while the unmodified alkyd coatings did not skin. A 30% solids coating formulation of the FPA modified resin showed
shorter surface dry time but longer hard dry time than the unmodified alkyd resin coating. 相似文献
993.
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
994.
Electrical resistance heating (ERH) has become a common method of remediation for volatile organic compounds (VOCs) in unconsolidated soils, both above and below the water table. Recently, use of ERH has expanded to include treatment of contaminated sedimentary bedrock. This article describes the implementation issues for rock remediation and provides case studies of three sites remediated by ERH in Maryland, New Jersey, and Indiana. With proper design, remediation of bedrock can be as effectively completed as remediation of overburden materials. © 2010 Wiley Periodicals, Inc. 相似文献
995.
Humans can dive with critically endangered grey nurse sharks (Carcharias taurus) along the east coast of Australia. This study investigated both compliance of tourist divers to a code of conduct and legislation
and the behaviour of grey nurse sharks in the presence of divers. A total of 25 data collection dives were conducted from
December 2008 to January 2009. Grey nurse shark and diver behaviour were documented using 2-min scan samples and continuous
observation. The proportion of time spent observing human–shark interactions was 9.4% of total field time and mean human–shark
interaction time was 15.0 min. Results were used to gauge the effectiveness of current management practices for the grey nurse
shark dive industry at Fish Rock in New South Wales, Australia. Grey nurse shark dive tourists were compliant to stipulations
in the code of conduct and legislation (compliance ranged from 88 to 100%). The research detailed factors that may promote
compliance in wildlife tourism operations such as the clarity of the stipulations, locality of the target species and diver
perceptions of sharks. Results indicated that grey nurse sharks spent the majority of their time milling (85%) followed by
active swimming (15%). Milling behaviour significantly decreased in the presence of more than six divers. Distance between
sharks and divers, interaction time and number of sharks were not significantly correlated with grey nurse shark school behaviour.
Jaw gaping, rapid withdrawal and stiff or jerky movement were the specific behaviours of grey nurse sharks that occurred most
frequently and were associated with distance between divers and sharks and the presence of six or more divers. Revision of
the number of divers allowed per interaction with a school of grey nurse sharks and further research on the potential impacts
that shark-diving tourism may pose to grey nurse sharks is recommended. 相似文献
996.
Robert J. Pheasant Mark N. Fisher Greg R. Watts David J. Whitaker Kirill V. Horoshenkov 《Journal of environmental psychology》2010,30(4):501-509
In a world of sensory overload, it is becoming increasingly important to provide environments that enable us to recover our sense of well being. Such restorative (‘tranquil’) environments need to comprise sufficient sensory stimulation to keep us engaged, whilst at the same time providing opportunity for reflection and relaxation. One essential aspect in safeguarding existing, or developing new ‘tranquil space’, is understanding the optimum relationship between the soundscape and the visual composition of a location. This research represents a first step in understanding the effects of audio-visual interaction on the perception of tranquillity and identifies how the interpretation of acoustic information is an integral part of this process. By using uni and bi-modal auditory-visual stimuli in a two stage experimental strategy, it has been possible to measure the key components of the tranquillity construct. The findings of this work should be of particular interest to those charged with landscape management, such as National Park Authorities, Regional Councils, and other agencies concerned with providing and maintaining public amenity. 相似文献
997.
Zhou X Helmers MJ Asbjornsen H Kolka R Tomer MD 《Journal of environmental quality》2010,39(6):2006-2015
Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3-N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed-scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20 PFS (distributed on toe and as contour strips). All treatments were established in fall 2006 on watersheds that were under bromegrass (Bromus L.) cover for at least 10 yr. Nonperennial areas were maintained under a no-till 2-yr corn (Zea mays L.)--soybean [Glycine max. (L.) Merr.] rotation since spring 2007. Suction lysimeter and shallow groundwater wells located at upslope and toeslope positions were sampled monthly during the growing season to determine NO3-N concentration from 2005 to 2008. The results indicated significant increases in NO3-N concentration in soil and groundwater following grassland-to-cropland conversion. Nitrate-nitrogen levels in the vadose zone and groundwater under PFS were lower compared with 100% cropland, with the most significant differences occurring at the toeslope position. During the years following conversion, PFS mitigated increases in subsurface nitrate, but long-term monitoring is needed to observe and understand the full response to land-use conversion. 相似文献
998.
This work was undertaken to analyze nutrient contents of vegetation in an alpine meadow—Tungnath, North-West Himalaya, India.
The study pertains to the uptake, transfer and release of four main macronutrients (organic carbon, total nitrogen, total
potassium and total phosphorus) in grazed (exposed to extensive grazing by cattles) and ungrazed (grazing completely prohibited)
communities. Mineral concentration was recorded higher for the ungrazed sites compared to the grazed sites, and maximum standing
state of nutrients was found in roots. Belowground compartment (roots) contributed maximum share of mineral elements to soil.
Litter nutrients release was low because of low microbial activity and continuous removal of phytomass. Observations reveal
that there was very little amount of nutrient release from phytomass and vegetation in alpine are very poor source of mineral
recycling. Low transfer rate of minerals from one compartment to other is adequate for greater amount of these minerals that
are translocated back into the storage organs. A small proportion get removed through rain splash or through the removal of
hay during grazing as relatively high release rates in ungrazed sites when compared to grazed sites was observed. This translocation
can be considered as an important adaptation in alpine plants for survival during adverse environmental conditions, against
all types of biotic pressures and also for regeneration in the forthcoming growing season. 相似文献
999.
Ruchi Badola Syed Ainul Hussain Bidyut Kumar Mishra Bidyarani Konthoujam Sneha Thapliyal Parag Madhukar Dhakate 《The Environmentalist》2010,30(4):320-329
This paper examines the economic value of selected ecosystem services of Corbett Tiger Reserve, India. The direct cost was
derived from secondary sources, and indirect and opportunity costs through socioeconomic surveys. For recreational value the
individual approach to travel cost method was used, and to assess carbon sequestration the replacement cost method was used.
The maintenance cost of the reserve was estimated as US $2,153,174.3 year−1. The indirect costs in terms of crop and livestock depredation by wild animals ranged from US $2,153,174.3 year−1. The indirect costs in terms of crop and livestock depredation by wild animals ranged from US 2,408 to US $37,958 village−1 over a period of 5 years. The dependence of local communities was for fuel wood (US $37,958 village−1 over a period of 5 years. The dependence of local communities was for fuel wood (US 7,346 day−1), fodder (US $5,290 day−1), small timber, and other nontimber forest products. The recreational value of the reserve was estimated as US $5,290 day−1), small timber, and other nontimber forest products. The recreational value of the reserve was estimated as US 167,619 year−1. With the cost per visitor being US $2.5, the consumers’ surplus was large, showing the willingness of visitors to pay for
wildlife recreation. The forests of the reserve mitigate carbon worth US $2.5, the consumers’ surplus was large, showing the willingness of visitors to pay for
wildlife recreation. The forests of the reserve mitigate carbon worth US 63.6 million, with an annual flow of US $65.0 ha−1 year−1. The other benefits of the reserve include US $65.0 ha−1 year−1. The other benefits of the reserve include US 41 million through generation of electricity since 1972. The analysis reveals
that, though the benefits outweigh costs, they need to be accrued to local communities so as to balance the distribution of
benefits and costs. 相似文献
1000.
By means of environmental education, teachers are supposed to intervene in pupils’ awareness and concern of environmental
issues. Teachers’ environmental attitudes, however, have rarely been studied. We analysed 367 German pre- and in-service teachers’
environmental attitudes for their structure and socio-economic correlates within the frame of a European project. Thus, we
retrieved for adults the two-dimensional model of ecological values (2-MEV) presented for adolescents by Bogner and Wiseman
(Sci Educ Int 15(1):27–48, 2004). For the two domains, Preservation and Utilisation, the psychometric structure was confirmed and discriminative correlations
with age, gender and teaching subject were unveiled. Further research is needed to deduce the implications for teaching practice. 相似文献