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501.
Environmentally Friendly Polyurethane Composites: Preparation, Characterization and Mechanical Properties 总被引:1,自引:0,他引:1
J. L. Zhang D. M. Wu D. Y. Yang F. X. Qiu 《Journal of Polymers and the Environment》2010,18(2):128-134
The waterborne polyurethane (PU) prepolymer was prepared based on isophorone diisocyanate (IPDI), polyester polyol (N220), dimethylol propionic acid (DMPA) and hydroxyethyl methyl acrylate (HEMA). The modified waterborne polyurethane–acrylate (PUA) emulsions were obtained with different proportions of acrylate (butyl acrylate and methyl methacrylate) and initiating agent by in situ dispersion technique. The structures and thermal properties of prepared PU and PUA were analyzed and characterized with FT-IR, UV–Vis spectroscopy and DSC. The PUA hybrid samples had lower glass transition temperature of hard segment and higher decomposition temperatures than PU sample. Performances of the emulsion and film were studied by means of apparent viscidity, particle size and polydispersity, surface tension and mechanical properties. The results indicated that the particle sizes of the PUA dispersions were larger than those of the pure PU and the solvent resistance, mechanical properties of PUA films was improved compare with the unmodified polyurethane film. The film had the biggest hardness and the least water absorption when the BA/MMA mass ratio 5:5 modified PU. The obtained PUA have great potential application such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes. 相似文献
502.
Patrick L. Hanrahan 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1332-1338
ABSTRACT A previous paper1 discusses the methodology for a new method for deriving the nitrogen dioxide/nitrogen oxide (NO2/NOx) ratio in plumes that originally are composed mainly of (NOx). It is called the Plume Volume Molar Ratio Method (PVMRM). This paper documents its performance against six different data sets. These performance evaluations show that the PVMRM can realistically predict the NO2 fraction at close-in receptors yet still provide conservative estimates so that the air quality standards can be protected. 相似文献
503.
504.
A. P. Altshuller S. L. Kopczynski D. Wilson W. Lonneman F. D. Sutterfield 《Journal of the Air & Waste Management Association (1995)》2013,63(10):791-794
Effects associated with photochemical air pollution were measured during irradiation of n-butane-nitrogen oxide or n-butane-ethane-nitrogen oxide mixtures, with small amounts of propylene or toluene added. The effects measured including nitrogen dioxide and oxidant dosages, yields of formaldehyde and peroxy-acetyl nitrate, and eye irritation response. The results obtained clearly show that beneficial effects result from selective changes in hydrocarbon composition as well as from reduction of total hydrocarbon concenfration. Exclusion of olefins and alkylbenzenes was highly effective in reducing oxidant dosage, formaldehyde and peroxyacetyl nitrate concentrations, and eye irritation response. The only penalty was a modest increase in nitrogen dioxide dosage. A large reduction in nitrogen oxide concentration reduced nitrogen dioxide dosage and eye irritation response, but with the penalty of a large increase in oxidant dosage. The desirability of preferentially reducing olefins and alkylbenzenes rather than paraffinic hydrocarbons, acetylene, and benzene is strongly supported by this study. Research and development efforts should be directed toward preferential hydrocarbon control by mechanical or catalytic control 相似文献
505.
506.
Igor Linkov Matthew D. Wood Renae Ditmer Anthony Cox Robert Ross 《The Environmentalist》2013,33(3):335-340
Individuals make decisions every day in group contexts which vary in size, structure, and purpose. The US Department of Defense (DoD) is a large organization composed of many groups, and like many organizations, it has a vested interest in improving the performance of its affiliated groups, especially as it concerns risk-informed decision-making. This article discusses current foibles and considerations for decision-making in DoD groups as identified through a workshop with experts in risk-informed decision-making, cognitive science, and military operations. Experts noted that terms associated with risk-informed decision-making were often misconstrued, that formal decision-making frameworks are underutilized, and that many considerations should be taken into account when attempting to improve decision-making performance. 相似文献
507.
REED F. NOSS ERICA FLEISHMAN† DOMINICK A. DELLASALA‡ JOHN M. FITZGERALD§ MART R. GROSS MARTIN B. MAIN†† FIONA NAGLE‡‡ STACEY L. O'MALLEY JON ROSALES§§ 《Conservation biology》2009,23(4):825-833
Abstract: The Society for Conservation Biology (SCB) can enhance conservation of biodiversity in North America by increasing its engagement in public policy. Toward this end, the North America Section of SCB is establishing partnerships with other professional organizations in order to speak more powerfully to decision makers and taking other actions—such as increasing interaction with chapters—geared to engage members more substantively in science-policy issues. Additionally, the section is developing a North American Biodiversity Blueprint, which spans the continental United States and Canada and is informed by natural and social science. This blueprint is intended to clarify the policy challenges for protecting continental biodiversity, to foster bilateral collaboration to resolve common problems, and to suggest rational alternative policies and practices that are more likely than current practices to sustain North America's natural heritage. Conservation scientists and practitioners can play a key role by drawing policy makers' attention to ultimate, as well as proximate, causes of biodiversity decline and to the ecological and economic consequences of not addressing these threats. 相似文献
508.
Salinity levels vary spatially in coastal areas, depending on proximity to freshwater sources, and may also be slowly decreasing
as a result of anthropogenic climatic changes. The impact of salinity on host–parasite interactions is potentially a key regulator
of transmission processes in intertidal areas, where trematodes are extremely common parasites of invertebrates and vertebrates.
We investigated experimentally the effects of long-term exposure to decreased salinity levels on output of infective stages
(cercariae) and their transmission success in the trematode Philophthalmus sp. This parasite uses the snail Zeacumantus subcarinatus as intermediate host, in which it asexually produces cercariae. After leaving the snail, cercariae encyst externally on hard
substrates to await accidental ingestion by shorebirds, which serve as definitive hosts. We found that at reduced salinities
(25 or 30 psu), the cercarial output of the parasite was lower, the time taken by cercariae to encyst was longer, fewer cercariae
successfully encysted and encysted parasites had lower long-term survival than at normal seawater salinity (35 psu). The strong
effect of salinity on the replication and transmission of this parasite suggests that there may be sources and sinks of transmission
to birds along coastal areas, depending on local salinity conditions. Also, unless it evolves to adapt to changing conditions,
the predicted reduction in salinity as a consequence of climate change may have negative impact on the parasite’s abundance. 相似文献
509.
510.
Gómez-Tolosa María Rivera-Velázquez Gustavo Rioja-Paradela Tamara M. Mendoza-Cuenca Luis F. Tejeda-Cruz César López Sergio 《Environmental science and pollution research international》2021,28(2):1381-1396
Environmental Science and Pollution Research - The order Odonata has been regularly used as an indicator of the ecosystem’s condition. The objective of this review was to analyze the... 相似文献