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991.
Grundl TJ Aldstadt JH Harb JG St Germain RW Schweitzer RC 《Environmental science & technology》2003,37(6):1189-1197
We describe the development of a novel method for real-time in situ characterization of polycyclic aromatic hydrocarbons (PAHs) in submerged freshwater sediments. Laser-induced fluorescence (LIF) spectroscopy, a mature technique for PAH characterization in terrestrial sediments, was adapted for shipboard use. A cone penetrometer-type apparatus was designed for probe penetration at a constant rate (1 cm/s) to a depth of 3 m. A field-portable LIF system was used for in situ measurements in which the output of a pulsed excimer laser was transmitted by optical fiber to a sapphire window (6.4-mm o.d.) in the probe wall; fluorescent emission was collected by a separate optical fiber for transmission to the spectrometer on deck. Four wavelengths (340, 390, 440, 490 nm) were selected via optical delay lines, and multiple-wavelength waveforms were created. These multiple-wavelength waveforms contain information on the fluorescence frequency, intensity, and emission decay rate. Field testing was conducted at 10 sites in Milwaukee Harbor (total PAH concentrations ranged from approximately 10 to 650 microg/g); conventional sediment core samples were collected concurrently. The core samples were analyzed by EPA methods 3545 (pressurized fluid extraction, PFE) and 8270C (gas chromatography-mass spectrometry, GC-MS) for PAHs. A partial least-squares regression (PLSR) model wasthen created based on laboratory LIF measurements and PFE-GC-MS of the core samples. The PLSR model was applied to the in situ field test data, and 13 of the 16 EPA-regulated PAHs were quantified with a relative error of <30% overall (the remaining three PAHs were found at levels insufficient to quantify). We additionally describe preliminary source apportionment relationships that were revealed by the PLSR model for the in situ LIF measurements. 相似文献
992.
993.
Chiedozie N Egesi Robert Asiedu James K Egunjobi Mpoko Bokanga 《Journal of the science of food and agriculture》2003,83(8):858-865
Improving the food quality of yams (Dioscorea spp) is an ongoing challenge to yam breeders and researchers. Forty accessions of D alata were evaluated for the suitability of their tubers for the preparation of two dominant food forms (boiled and pounded) as part of an effort to identify potential parents for use in genetic improvement. Trained panellists were presented with randomised, replicated and coded samples of boiled yam tuber pieces and asked to rate them for mealiness, colour, wetness, softness and taste. The sensory attributes considered for pounded yam (dough from boiled and pounded tubers) were consistency, colour, sheen, smoothness, stickiness, elasticity and hardness. Ratings were based on hedonic scales. Cluster analysis revealed groupings of accessions into eight and nine similarity clusters for boiled yam and pounded yam respectively. The mean scores for general preference were regressed on individual attribute scores. Mealiness, colour and taste were important in the general preference for boiled yam. Consistency, colour and stickiness determined the general preference for pounded yam. Of the accessions, 67% were identified as being suitable for preparation as a boiled vegetable, while 55% were assessed to be good for pounded yam, based on the respective quality attributes evaluated. © 2003 Society of Chemical Industry 相似文献
994.
Bei‐Zhong Han Jia‐Huai Wang Frans M Rombouts MJ Robert Nout 《Journal of the science of food and agriculture》2003,83(9):899-904
Sufu is made by solid state fungal fermentation (using Actinomucor elegans) of tofu, followed by salting and maturation in dressing mixtures containing salt, alcohol and various other ingredients. NaCl in dressing mixtures strongly affected the changes in textural properties and the hydrolysis of protein and lipid of sufu. Higher salt contents (14% w/w) resulted in increased hardness (+100%) and elasticity (+18%) and reduced adhesiveness (?30%). Hardness and elasticity could be used to judge the extent of sufu ripening. SDS‐PAGE showed the disappearance of all protein subunits at 80 and 110 g kg?1 salt content; however, some protein subunits were still detectable at 140 g kg?1 salt content after 60 days of ripening. Higher ratios of free amino nitrogen to total nitrogen (FAN/TN = 0.4–0.45) and free amino acids to crude protein (FAA/CP = 0.24–0.26) were observed in sufu with lower (80 g kg?1) salt content. FAN/TN and FAA/CP in white sufu (obtained with dressing mixtures containing only salt and alcohol) were higher than those in red sufu (obtained with dressing mixtures containing angkak or kojic red rice) owing to different dressing mixture compositions. Increases in free fatty acids (FFA) were also observed during ripening. FFA levels in sufu with lower salt content increased rapidly during the first 30–40 days and then increased slowly, probably resulting from the formation of fatty acid esters. Lowering the salt content (80 g kg?1) can shorten the ripening time to 40 days, which is of benefit to manufacturers. However, sufu will spoil, ie undergo souring, during the ripening stage at salt contents of 50 g kg?1 or lower. Copyright © 2003 Society of Chemical Industry 相似文献
995.
Effective preharvest strategies to eliminate aflatoxin accumulation in crops are not presently available. The molecular biology of aflatoxin biosynthesis has been extensively studied, and genetic and molecular tools such as reporter gene systems for the measurement of fungal growth have been developed. A reporter construct containing the Aspergillus flavus beta-tubulin gene promoter fused to Escherichia coli beta-glucuronidase (GUS) has been shown to be a reliable tool for the indirect measurement of fungal growth in maize kernels. Since cost-saving alternative methods for the direct measurement of aflatoxin levels are needed to facilitate more widespread field and laboratory screening of maize lines, a new reporter gene construct involving the promoter region of the omtA gene of the aflatoxin biosynthetic pathway was constructed and tested. Expression of GUS activity by this construct (omtA::GUS) was correlated with aflatoxin accumulation in culture. In the fungal transformant GAP26-1, which harbors this construct, aflatoxin production and GUS expression on sucrose-containing medium showed the same temporal pattern of toxin induction. Furthermore, GUS expression by GAP26-1 was shown to be associated with aflatoxin accumulation in maize kernels inoculated with this strain. Our results suggest that this and other reporter gene pathway promoter constructs may provide superior alternatives to direct aflatoxin quantification with respect to time, labor, and materials for the screening of maize lines for resistance to aflatoxin accumulation. 相似文献
996.
Martina Nádherná Jakub Reiter Jo?e Moškon Robert Dominko 《Journal of power sources》2011,196(18):7700-7706
Lithium bis(fluorosulfonyl)imide (LiFSI) in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) was successfully tested as an electrolyte for graphite composite anodes at elevated temperature of 55 °C. The graphite anode showed a good cyclability during the galvanostatic testing at C/10 rate and 55 °C with the capacity close to theoretical. The formation of SEI in different electrolytes was the subject of study using impedance spectroscopy on symmetrical cells containing two lithium electrodes. The 0.7 m LiFSI in PYR14TFSI exhibits a good ionic conductivity (5.9 mS cm−1 at 55 °C) along with high electrochemical stability and high thermal stability. These properties allow their potential application in large-scale lithium ion batteries with improved safety. 相似文献
997.
The potential impacts of climate-change policy on freshwater use in thermoelectric power generation 总被引:1,自引:0,他引:1
Climate change policy involving a price on carbon would change the mix of power plants and the amount of water they withdraw and consume to generate electricity. We analyze what these changes could entail for electricity generation in the United States under four climate policy scenarios that involve different costs for emitting CO2 and different technology options for reducing emissions out to the year 2030. The potential impacts of the scenarios on the U.S. electric system are modeled using a modified version of the U.S. National Energy Modeling System and water-use factors for thermoelectric power plants derived from electric utility data compiled by the U.S. Energy Information Administration. Under all the climate-policy scenarios, freshwater withdrawals decline 2–14% relative to a business-as-usual (BAU) scenario of no U.S. climate policy. Furthermore, water use decreases as the price on CO2 under the climate policies increases. At relatively high carbon prices (>$50/tonne CO2), however, retrofitting coal plants to capture CO2 increases freshwater consumption compared to BAU in 2030. Our analysis suggests that climate policies and a carbon price will reduce both electricity generation and freshwater withdrawals compared to BAU unless a substantial number of coal plants are retrofitted to capture CO2. 相似文献
998.
Suresh B. Sadineni Srikanth Madala Robert F. Boehm 《Renewable & Sustainable Energy Reviews》2011,15(8):3617-3631
A significant portion of the total primary energy is consumed by today's buildings in developed countries. In many of these buildings, the energy consumption can be significantly reduced by adopting energy efficiency strategies. Due to environmental concerns and the high cost of energy in recent years there has been a renewed interest in building energy efficiency. This article strives to make an exhaustive technical review of the building envelope components and respective improvements from an energy efficiency perspective. Different types of energy efficient walls such as Trombe walls, ventilated walls, and glazed walls are discussed. Performance of different fenestration technologies including aerogel, vacuum glazing and frames are presented. Advances in energy efficient roofs including the contemporary green roofs, photovoltaic roofs, radiant-transmittive barrier and evaporative roof cooling systems are discussed. Various types of thermal insulation materials are enumerated along with selection criteria of these materials. The effects of thermal mass and phase change material on building cooling/heating loads and peak loads are discussed. Application of thermal mass as an energy saving method is more effective in places where the outside ambient air temperature differences between the days and nights are high. Air tightness and infiltration of building envelopes are discussed as they play a crucial role in the energy consumption of a building. Energy efficiency approaches sometimes might not require additional capital investment. For example, a holistic energy efficient building design approach can reduce the size of mechanical systems compensating the additional cost of energy efficiency features. 相似文献
999.
Robert J van Barneveld Stephen R Szarvas Andrew R Barr 《Journal of the science of food and agriculture》1998,76(2):277-284
An experiment was conducted to determine the apparent ileal digestibility of amino acids and the digestible energy (DE) content of two samples of naked oats (Avena sativa cv Bandicoot) and to compare these parameters in wheat (Triticum aestivum cv Machete) and dehulled oats (groats; Avena sativa cv Echidna). Four Large White male pigs were fitted with simple T-piece ileal cannulae and allocated to experimental diets in a 4×4 Latin square design. Amino acid digestibility coefficients were determined after continuous eight hour collections of digesta over two consecutive days using acid-insoluble ash as an indigestible marker. Digestible energy was determined using grab samples of faeces. No significant difference between the four test cereals was found in the digestibility of all amino acids, except for proline and lysine. The apparent ileal digestibility of lysine in wheat (0·87) and two samples of naked oats (0·89 and 0·82, respectively) was lower (P<0·05) than dehulled oats (0·91). The mean DE value of the naked oats samples was 16·96 MJ kg−1 (air-dry basis). The results suggest that Bandicoot naked oats and dehulled oats are superior amino acid and DE sources to wheat and have potential for use in weaner and grower pig diets. © 1998 SCI. 相似文献
1000.
Abstract Lakes develop when pits from open cut mines are left to fill with groundwater. In recent years, mining companies, mining communities,
and regulatory agencies have begun to consider potential beneficial end uses for mine lakes. Beneficial end uses are unlikely
to be without environmental impacts, however, and a proper consideration of the total benefit to the community should consider
them. This paper briefly reviews potential beneficial end uses and possible environmental impacts that might arise with them
for mine lakes in the Collie Basin, a coal mining region in Western Australia. We identified eight distinct, but not necessarily
incompatible, end uses from a search of the literature on mine lakes throughout the world: recreation and tourism, wildlife
conservation, aquaculture, irrigation, livestock water, potable water, industrial water, and chemical extraction. Recreation,
conservation, and possibly aquaculture use the mine lake directly, whereas the other end uses utilise extracted water. All
end uses have the potential to have environmental effects, with the most common being an actual or perceived impact on human
health and safety. A semi-quantitative risk assessment, using published literature sources, identified wildlife conservation
as the end use with the least environmental risk, and irrigation as the end use with the greatest environmental risk. Such
risks need to be balanced against economic and social benefits. There is an urgent need for a regulatory framework to address
mine lake options. 相似文献