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911.
Carl L. Yaws Ku-Yen Li Thomas C.T. Chu C.S. Fang Ralph Lutwack Anthony Briglio Jr. 《Solar Energy》1981,27(6):539-546
New technologies for producing polysilicon are being developed to provide lower cost material for solar cells which convert sunlight into electricity. This article presents results for a process to produce dichlorosilane (DCS) as a silicon source material for solar energy silicon. Major benefits of dichlorosilane include faster chemical vapor deposition of silicon and higher chemical equilibrium yield for silicon production. Hemlock Semiconductor Corporation has recently demonstrated that under comparable conditions and for rods up tp 42 mm dia., deposition rates and conversions for dichlorosilane are approximately twice those for trichlorosilane. Cost, sensitivity and profitability analysis results are presented based on a preliminary process design of a plant to produce dichlorosilane by the DCS process. Profitability analysis indicates a sales price of $1.29–$1.47/kg of dichlorosilane (1980 dollars) at a 0–15 per cent discounted cash flow rate of return after taxes. These results indicate good potential for dichlorosilane as a silicon source material to provide lower cost material for solar cells. 相似文献
912.
Biochar, unwashed and washed with a solution of Triton and hydrogen peroxide, was wet drum granulated using molasses binder solutions. Unwashed biochar was very hydrophobic and granulation proceeded through forming liquid marbles and layering. Washing reduced the hydrophobicity of the biochar. The effectiveness of the wash depended on the biochar source; it significantly reduced the hydrophobicity of biochar from woodchips and moderately reduced the hydrophobicity of biochar from flower digestate. Therefore, washed biochar from woodchips was granulated using a hydrophilic mechanism, while washed biochar from digestate was granulated according to a combination mechanism of liquid marbles collapsing and then coalescing. The change in granulation mechanism produced stronger and denser granules with higher yields of granules in the 1–4 mm optimal size range. Washing and then granulating biochar created a product that could be further tailored for optimal soil amendment. 相似文献
913.
Nanostructured films of the conducting polymer polyaniline (PANI) were prepared by its potentiostatic polymerization in the presence of thin polystyrene (PS) nanoparticle templates. Two sizes of PS nanoparticles were used (50 and 100 nm) and electron microscopic analysis showed that core–shell composite films of PANI (PANI–PS50 and PANI–PS100) and, following removal of the PS, hollow structures (PANI50 and PANI100) were formed due to the growth mechanism of PANI around the PS templates. The electrochemical behaviour of the PANI-modified electrodes was studied by cyclic voltammetry, chronocoulometry and amperometry in the presence of nitrite and it was found that nitrite reduction was enhanced by the nanostructuring of the films. The electrocatalysis was dependent on the size of the template, being more pronounced at 50 nm than at 100 nm. The hollow PANI50 film was also a better catalyst than PANI–PS50, whereas for structures based on 100 nm templates, the composite film was better. Such behaviour could be explained in terms of larger surface area and surface concentration of PANI50 and PANI–PS50 films on the electrodes and by higher differential capacitance of those films. 相似文献
914.
Jaffe D Chand D Hafner W Westerling A Spracklen D 《Environmental science & technology》2008,42(16):5885-5891
Because forest fires emit substantial NOx and hydrocarbons--known contributors to O3 production--we hypothesize that interannual variation in western U.S. O3 is related to the burned area. To evaluate this hypothesis we used a gridded database of western U.S. summer burned area (BA) and biomass consumed (BC) by fires between 101-125 degrees W. The fire data were compared with daytime summer O3 mixing ratios from nine rural Clean Air Status and Trends Network (CASTNET) and National Park Service (NPS) sites. Large fire years exhibited widespread enhanced O3. The summer BA was significantly correlated with O3 at all sites. For each 1 million acres burned in the western U.S. during summer, we estimate that the daytime mean O3 was enhanced across the region by 2.0 ppbv. For mean and maximum fire years, O3 was enhanced by an average of 3.5 and 8.8 ppbv, respectively. At most sites O3 was significantly correlated with fires in the surrounding 5 x 5 degrees and 10 x 10 degrees regions, but not with fires in the nearest 1 x 1 degree region, reflecting the balance between O3 production and destruction in a high NOx environment. BC was a slightly better predictor of O3, compared with BA. The relationship between O3 and temperature was examined at two sites (Yellowstone and Rocky Mountain National Parks). At these two sites, high fire years were significantly warmer than lowfire years; however, daytime seasonal meantemperature and O3 were not significantly correlated. This indicates that the presence of fire is a more important predictor for O3 than is temperature. 相似文献
915.
Díaz FJ Chow AT O'Geen AT Dahlgren RA Wong PK 《Environmental science & technology》2008,42(16):5992-5997
The effects of a restored wetland system in the Sacramento Valley, California on the production of dissolved organic carbon (DOC) and nitrogen (DON) and the formation potential of common disinfection byproducts (DBPs: trihalomethanes, haloacetonitriles, and chloral hydrate) were examined. Additionally, the effects of photodegradation and microbial degradation on dissolved organic matter properties and reactivitywith respect to DBP formation potential (DBP-FP) were evaluated. The wetlands increased DOC and DON concentrations by a factor of 2.2 and 1.9 times, respectively, but had little influence on the DOC and DON quality as compared to their source waters. The increase in DOC and DON concentrations increased the formation potential of all DBP species by >100%. Solar radiation and microbial degradation reduced the trihalomethane formation potential by 24 and 10%, respectively, during a 14 day incubation. In contrast, the chloral hydrate formation potential was increased by 22% after phototreatment. Results indicate that current flood-pulse management practices with a 2-3 week residence time could lead to wetlands acting as a source of DBP precursors. Enhanced DBP-FP is especially important as these wetlands contribute to a watershed that is a drinking water source for more than 23 million people. 相似文献
916.
Jérôme Andrieux Dariusz Swierczynski Laetitia Laversenne Anthony Garron Simona Bennici Christelle Goutaudier Philippe Miele Aline Auroux Bernard Bonnetot 《International Journal of Hydrogen Energy》2009
In the present work, hydrogen generation through hydrolysis of a NaBH4(s)/catalyst(s) solid mixture was realized for the first time as a solid/liquid compact hydrogen storage system using Co nanoparticles as a model catalyst. The performance of the system was analysed from both the thermodynamic and kinetic points of view and compared with the classical catalyzed hydrolysis of a NaBH4 solution. The kinetic analysis of the NaBH4(s)/catalyst(s)/H2O(l) system shows that the reaction is first order with respect to the catalyst concentration, and the activation energy equal to 35 kJ molNaBH4−1. Additionally, calorimetric measurements of the heat evolved during the hydrolysis of NaBH4 solutions evidence the global process energy (−217 kJ molNaBH4−1). Characterization of the cobalt nanoparticles before and after the hydrolysis associated with the calorimetric measurements suggests the “in situ” formation of a catalytically active CoxB phase through “reduction” of an outer protective oxide layer that is regenerated at the end of reaction. 相似文献
917.
Christopher Johnson Nina Orlovskaya Anthony Coratolo Caleb Cross Junwei Wu Randall Gemmen Xingbo Liu 《International Journal of Hydrogen Energy》2009
For IT-SOFC metallic interconnects, surface coating is effective for reducing Cr poisoning of the cathode and controlling scale growth. In this work, LaCrO3 and doped LaCrO3 coatings were deposited by magnetron sputtering on SS446 and Crofer 22 APU substrates. The crystallization process was studied by means of X-ray Diffraction (XRD) during the annealing of the sputter coated samples in ambient and reducing environments. The formation of intermediate phases when annealed in air, LaCrO4 and La2CrO6, results in vacancy formation upon subsequent transformation to the LaCrO3 phase and thus a decreased oxidation resistance. While the avoidance of an intermediate phase change when the coatings are initially annealed in a reducing environment leads to dense and compact coatings. This confirmed both by XRD and by scanning electron microscopy (SEM) of coating cross-sections. Crofer 22 APU alloys with various silicon and aluminum levels are deposited with doped LaCrO3 coating to study substrate impurity effects on coating properties. It was found that silicon content in the substrates leads to increased ASR of the coatings. In addition, long term annealing in air shows that aluminum impurities in the substrate can lead to the formation of alumina at substrate grain boundaries, which in turn leads to enhanced Mn migration at the grain boundaries. Increased manganese concentrations at the film/grain boundary interface in coated samples produces larger than normal amounts of (Mn,Cr)3O4 spinel in these regions, which cracks the coating and reduces the ASR value due to extra electronic conduction path. A similar mechanism is not observed in a low Al/Si alloy. 相似文献
918.
In the context of climate change, efficiency and energy security, biomass gasification is likely to play an important role. Circulating fluidised bed (CFB) technology was selected for the current study. The objective of this research is to develop a computer model of a CFB biomass gasifier that can predict gasifier performance under various operating conditions. An original model was developed using ASPEN Plus. The model is based on Gibbs free energy minimisation. The restricted equilibrium method was used to calibrate it against experimental data. This was achieved by specifying the temperature approach for the gasification reactions. The model predicts syn-gas composition, conversion efficiency and heating values in good agreement with experimental data. Operating parameters were varied over a wide range. Parameters such as equivalence ratio (ER), temperature, air preheating, biomass moisture and steam injection were found to influence syn-gas composition, heating value, and conversion efficiency. The results indicate an ER and temperature range over which hydrogen (H2) and carbon monoxide (CO) are maximised, which in turn ensures a high heating value and cold gas efficiency (CGE). Gas heating value was found to decrease with ER. Air preheating increases H2 and CO production, which increases gas heating value and CGE. Air preheating is more effective at low ERs. A critical air temperature exists after which additional preheating has little influence. Steam has better reactivity than fuel bound moisture. Increasing moisture degrades performance therefore the input fuel should be pre-dried. Steam injection should be employed if a H2 rich syn-gas is desired. 相似文献
919.
Food Analytical Methods - Phytic acid is a compound regularly found in plant-based food and beverages. Although it may provide some health benefits to human body, it is commonly defined as an... 相似文献
920.
Robyn S. Lymbury Matthew J. Marino Anthony V. Perkins 《Molecular nutrition & food research》2010,54(10):1436-1444
Oxidative stress has been directly implicated in hypertension and myocardial remodelling, two pathologies fundamental to the development of chronic heart failure. Selenium (Se) can act directly and indirectly as an antioxidant and a lowered Se status leads to a higher risk of cardiovascular disease. This study examined the role of Se on the development of hypertension and subsequent progression to chronic heart failure in spontaneously hypertensive rats (SHR). Three dietary groups were studied: (i) Se‐free; (ii) normal Se (50 μg Se/kg food); and (iii) high Se (1000 μg Se/kg food). Systolic blood pressure and echocardiography were used to detect cardiac changes in vivo. At study end, cardiac tissues were assayed for glutathione peroxidase activity, thioredoxin reductase activity, and protein carbonyls. The major finding of this study was the high heart failure‐related mortality rate in SHRs fed an Se‐free diet (70%). Normal and high levels of dietary Se resulted in higher survival rates of 78 and 100%, respectively. Furthermore, high dietary Se was clearly associated with lower levels of cardiac oxidative damage and increased antioxidant expression, as well as a reduction in disease severity and mortality in the SHR. 相似文献