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排序方式: 共有2176条查询结果,搜索用时 15 毫秒
941.
Hopke PK Cohen DD Begum BA Biswas SK Ni B Pandit GG Santoso M Chung YS Rahman SA Hamzah MS Davy P Markwitz A Waheed S Siddique N Santos FL Pabroa PC Seneviratne MC Wimolwattanapun W Bunprapob S Vuong TB Duy Hien P Markowicz A 《The Science of the total environment》2008,404(1):103-112
Over the past decade, member states of the Regional Co-operation Agreement (RCA), an intergovernmental agreement for the East Asia and Pacific region under the auspices of the IAEA with the assistance of international organizations and financial institutions such as the World Bank and the Asian Development Bank, have started to set in place policies and legislation for air pollution abatement. To support planning and evaluate the effectiveness of control programs, data are needed that characterizes urban air quality. The focus of this measurement program describe in this report is on size segregated particulate air pollution. Such airborne particulate matter can have a significant impact on human health and urban visibility. These data provide the input to receptor models that may permit the mitigation of these impacts by identification and quantitative apportionment of the particle sources. The aim of this report is to provide an overview of the measurements of concentrations and composition of particulate air pollution in two size fractions across the participating countries. For many of the large cities in this region, the measured particulate matter concentrations are greater than air quality standards or guidelines that have been adopted in developed countries. 相似文献
942.
Andrzej Piasecki Dorota Piłakowska-Pietras Anna Baran Anna Krasowska 《Journal of surfactants and detergents》2008,11(3):187-194
A homologous series of surface active 2-(alkanoylamino)ethyldimethylamine-N-oxides, EDA-p(O), and 3-(alkanoylamino)propyldimethylamine-N-oxides, PDA-p(O), were synthesized. Their aqueous stock solutions were processed by the automatically operating apparatus to remove surface-active
contamination and provide chemical purity at the air/water interface. In case of 3-(tetradecanoylamino)propyldimethylamine-N-oxide, PDA-14(O), the difference between equilibrium surface tension values of the purified surfactant solutions and the corresponding values
of the solutions prepared from the “as received” compounds amounts to 15 mN m−1. Moreover, in presence of the surface-active contaminants time needed to reach equilibrium surface tension values is over
2 h. For the solution of the “surface-chemically pure” grade the change of the surface tension within adsorption time is negligible
and the equilibrium is reached instantaneously. Physicochemical properties of obtained surface-chemically pure aqueous solutions
of N-oxides of alkylamidoamines and adsorption parameters (standard free energy of adsorption, ΔG°ads, surface excess by saturation surface concentration, Γ∞, minimum surface area demand per molecule adsorbed, A
min) were evaluated from the equilibrium surface tension versus concentration isotherms at the air/water interface using Gibbs’s
equation. The introduction of the CH2 moiety into the intermediate part of molecule causes a slight decrease of the hydrophobic character of surfactant. Also the
minimum surface area demand, A
min, is slightly greater for PDA series than for the corresponding EDA derivatives. Surface potential measurements were performed in addition to surface tension studies. Electric surface potential
versus concentration isotherms was determined. Surface potential increases with increasing surfactant’s bulk concentration
for all investigated compounds. At highest concentrations, where interface is almost saturated, changes of surface potential
become almost negligible.
相似文献
Andrzej PiaseckiEmail: |
943.
Manganese(II) complexes {[MnII(bpy)2 2+]MeCN} in acetonitrile activate dioxygen for the oxidation of limonene to produce mainly carvone, carveol, limonene oxide, and perillaldehyde. The reaction efficiencies after 24 h reaction time are approximately 5-times higher than those obtained for analogous iron(II) complexes. However, the 5 h long induction period is observed for the common conditions of the reaction. The simultaneous presence of the catalyst, dioxygen and the substrate is necessary for the active species to be formed. When t-BuOOH is present in the reaction mixture, the induction period does not appear. In contrast, the replacement of t-BuOOH by HOOH completely inhibits the reaction. We have proposed a putative mechanism in which a manganese(IV)–hydroperoxo adduct with incorporated substrate is formed during the induction period and it becomes an active catalyst for limonene oxidation. 相似文献
944.
The conjugate Michael addition of methylamine to alkyl acrylates can be performed under mild conditions without a catalyst
to obtain new hydrophobic intermediates of aminodiester-type. The reactants used strictly in 1:2 molar ratio provide almost
quantitative yield of aminodiesters without formation of undesired aminoesters and any other by-products. Aminodiesters can
be purified if necessary by classical methods. The alkyl chain length in the acrylates used has no influence on the results.
相似文献
Andrzej PiaseckiEmail: |
945.
The paper reports experimental results concerning the influence of the support nature (TiO2, ZnO, Al2O3 and Al2O3–Fe2O3) of nickel catalysts on their activity, selectivity and coking phenomenon in the steam reforming of ethanol in the range of 570–870 K. The chemical transformations of ethanol occurring on the catalyst support make its chemical nature an important factor affecting the productivity and selectivity of the process. It was found that the most suitable supports in nickel catalysts designed for hydrogen generation in the steam reforming of ethanol are ZnO and TiO2. Taking into consideration both the efficiency of hydrogen generation and the intensity of carbon deposition, the optimum temperature of the process of the steam reforming of ethanol is below 750 K. An improvement in the selectivity of hydrogen generation and diminishing of the formation of undesirable products may be obtained by promoting nickel catalysts with sodium. 相似文献
946.
Wojewoda J Stefański A Wiercigroch M Kapitaniak T 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2008,366(1866):747-765
In this paper, the phenomena of hysteretic behaviour of friction force observed during experiments are discussed. On the basis of experimental and theoretical analyses, we argue that such behaviour can be considered as a representation of the system dynamics. According to this approach, a classification of friction models, with respect to their sensitivity on the system motion characteristic, is introduced. General friction modelling of the phenomena accompanying dry friction and a simple yet effective approach to capture the hysteretic effect are proposed. Finally, the experimental results are compared with the numerical simulations for the proposed friction model. 相似文献
947.
The effect of carrageenan and gelatine hydrosols incorporated with acidic electrolysed water on surface microbiota and quality changes on pork meat 下载免费PDF全文
Ewa Brychcy Żaneta Król Dominika Kulig Andrzej Jarmoluk 《International Journal of Food Science & Technology》2016,51(7):1618-1629
The aim of the study was to determine antimicrobial efficiency of carrageenan and gelatine hydrosols containing acidic electrolysed water (AEW) on surface microbiota of meat and evaluate possible quality changes in raw meat after treatment with experimental AEW‐containing hydrosols. Microbiological examination of meat samples covered with AEW‐containing hydrosols (total number of microorganisms, yeast and moulds, and psychrotrophs) was performed. To evaluate quality changes, haem pigments, colour, thiobarbituric acid‐reactive substances (TBARS), antioxidant capacity and preliminary sensory evaluations were performed. Treatment with AEW‐containing hydrosols causes improvement in microbiological quality of meat samples. The treatment with AEW‐containing hydrosols significantly influenced the variability of myoglobin forms of tested meat samples. Changes in L*a*b* colour parameters were found and favourably affected sensory evaluation of meat quality, especially for samples treated with AEW and gelatine‐containing hydrosols. The TBARS values of all AEW–sols‐treated samples were in the range of 0.30–0.39 mg malondialdehyde kg?1. Radical scavenging (DPPH) and reducing ability (FRAP) assays confirmed that process of electrolysis significantly improved antioxidant activity of modified meat samples compared to treatment with hydrosols containing nonelectrolysed salt solutions. Obtained results suggest that hydrosols incorporated with AEW may be used for food preservation because of their antimicrobial activity and positive impact on quality factors of raw meat. 相似文献
948.
Understanding the nature of interactions is regarded as one of the biggest challenges in projects related to complex adaptive systems. We discuss foundations for interactive computations in interactive intelligent systems (IIS), developed in the Wistech program and used for modeling complex systems. We emphasize the key role of risk management in problem solving by IIS. The considerations are based on experience gained in real-life projects concerning, e.g., medical diagnosis and therapy support, control of an unmanned helicopter, fraud detection algorithmic trading or fire commander decision support. 相似文献
949.
Dairy cows in early lactation are often housed in a large group, where they may have to compete for access to feed and space. However, a cow's ability to compete may be impaired due to production disease, and housing in a small group with minimal competition may be beneficial for cow welfare. The aim of this study was to investigate the effect of group size and health on social and feeding behavior of cows during the first 3 d after introduction to a new group. Data included 54 multiparous Holstein-Friesian cows that were moved from an individual maternity pen and individually joined an existing group pen for 6 (N6) or 24 cows (N24) on d 4 after calving. Cows were considered sick if they were diagnosed with and treated for milk fever, mastitis, or retained placenta, diagnosed with subclinical ketosis or metritis within 3 d of calving, or were diagnosed and treated for any other infection (n = 22; balanced across treatments). Stocking density of both pens was 100% at the feeding and lying areas. Behavioral data were collected from video recordings during the 1 d after introduction to the group pen, as well as via electronic feed bins and leg-attached accelerometers during the first 3 d after introduction to the group pen. No interactions between health status and group size were discovered. During the 1 d after introduction, N6 cows displaced other cows from feed less frequently than N24 cows (1.22 vs. 5.76 times/24 h), were less likely to access feed after a displacement (replacement; 0.29 vs. 1.67 times/24 h), and were less frequently being butted by another cow (0.42 vs. 1.69 times/24 h). Second-parity cows received more head butting than later-parity cows. Data obtained from feed bins showed that the number of replacements peaked on d 2 after introduction to the group pen. During the first 3 d we observed no effect of group size on DMI, but sick cows ate less than cows that were not sick (15.2 vs. 16.6 kg of DM/d). However, cows in N6 visited the feeder less often (42.4 vs. 55.6 times/d). Over the 3 d after introduction DMI and feeding time increased, whereas feeding rate decreased. Lying time and the number of lying bouts increased from d 1 to 2. The number of steps decreased over days, but the number of steps was higher among N24 than N6 cows on d 1 and d 2. Results suggest that cows experience less competition when moved to a smaller group after calving regardless of health status. Thus, minimizing competition by housing dairy cows in a small group for the first days after calving may improve cow welfare under commercial conditions. 相似文献
950.
A concept and a practical implementation of the algorithm for detecting of potentially dangerous situations related to crowding in passages is presented. An example of such a situation is a crush which may be caused by an obstructed pedestrian pathway. The surveillance video camera signal analysis performed in the online mode is employed in order to detect hold-ups near bottlenecks like doorways or staircases. The details of the implemented algorithm which uses the optical flow method combined with fuzzy logic are explained. The experiments were carried out on a set of gathered video recordings from the surveillance camera installed in the campus of Gdansk University of Technology. The results of experiments performed on gathered video recordings shows high efficiency of the algorithm. 相似文献