953 resultados para 670999 Ceramics, glass and industrial mineral products not elsewhere classified


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Lithological horizons have been distinguished in sediments cores from different parts of the Sea of Okhotsk based on primary descriptions of sediments and smear slides, and analyses of contents of both calcium carbonate and organic carbon, and opal. Sediment lithology has been correlated with oxygen isotope records and the standard isotope scale and radiocarbon data by AMS method for three cores studied in detail. This allowed to determine in detail periods of carbonaceous and diatomaceous ooze accumulation in the Sea of Okhotsk. Changes in magnetic susceptibility and grain size composition of sediments have been also compared with oxygen-isotope curves and radiocarbon datings. Obtained results confirm that variations in magnetic susceptibility are related with oxygen-isotope stages and influenced by climatic changes. Tephra interlayers K0, TR, K2, K3 have been identified by mineralogical analyses in all studied cores. Stratigraphic location of these tephra interlayers in detailed studied cores and their radiocarbon ages (8.1, 8.05, 26.8, and about 60 ka, respectively) provided base correlation between the interlayers and volcanic eruptions on the Kamchatka Peninsula and the Kuril Islands. This allows to use the former ones as time markers for deep-sea sediments of the Sea of Okhotsk. New lithostratigraphic and tephrochronologic data obtained allowed to correlate Upper Quaternary sediments from the Sea of Okhotsk.

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Appended: p. 343, resolutions of the Board regarding William T. Sutherlin; p. 347-357, A paper prepared by Hon. P. W. McKinney for the convention of southern governors ... and Virginia and her wealth by P. W. McKinney.

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The superplastic deformation behavior and superplastic forming ability of the Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass (BMG) in the supercooled liquid region were investigated. The isothermal tensile results indicate (hat the BMG exhibits a Newtonian behavior at low strain rates but a non-Newtonian behavior at hiqh-strain rates in the initial deformation stage. The maximum elongation reaches as high as 1624% at 656 K. and nanocrystallization was found to occur during the deformation process. Based cm the analysis on tensile deformation. a gear-like micropart is successfully die-forged via a superplastic forgings process. demonstrating that the BMG has excellent workability in the supercooled liquid region. (C) 2004 Elsevier B.V. All rights reserved.

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Bone is the second most widely transplanted tissue after blood. Synthetic alternatives are needed that can reduce the need for transplants and regenerate bone by acting as active temporary templates for bone growth. Bioactive glasses are one of the most promising bone replacement/regeneration materials because they bond to existing bone, are degradable and stimulate new bone growth by the action of their dissolution products on cells. Sol-gel-derived bioactive glasses can be foamed to produce interconnected macropores suitable for tissue ingrowth, particularly cell migration and vascularization and cell penetration. The scaffolds fulfil many of the criteria of an ideal synthetic bone graft, but are not suitable for all bone defect sites because they are brittle. One strategy for improving toughness of the scaffolds without losing their other beneficial properties is to synthesize inorganic/organic hybrids. These hybrids have polymers introduced into the sol-gel process so that the organic and inorganic components interact at the molecular level, providing control over mechanical properties and degradation rates. However, a full understanding of how each feature or property of the glass and hybrid scaffolds affects cellular response is needed to optimize the materials and ensure long-term success and clinical products. This review focuses on the techniques that have been developed for characterizing the hierarchical structures of sol-gel glasses and hybrids, from atomicscale amorphous networks, through the covalent bonding between components in hybrids and nanoporosity, to quantifying open macroporous networks of the scaffolds. Methods for non-destructive in situ monitoring of degradation and bioactivity mechanisms of the materials are also included. © 2012 The Royal Society.

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A LLE-GC-MS method was developed to detect PPCPs in surface water samples from Big Cypress National Park, Everglades National Park and Biscayne National Park in South Florida. The most frequently found PPCPs were caffeine, DEET and triclosan with detected maximum concentration of 169 ng/L, 27.9 ng/L and 10.9 ng/L, respectively. The detection frequencies of hormones were less than PPCPs. Detected maximal concentrations of estrone, 17β-estradiol, coprostan-3-ol, coprostane and coprostan-3-one were 5.98 ng/L, 3.34 ng/L, 16.5 ng/L, 13.5 ng/L and 6.79 ng/L, respectively. An ASE-SPE-GC-MS method was developed and applied to the analysis of the sediment and soil area where reclaimed water was used for irrigation. Most analytes were below detection limits, even though some of analytes were detected in the reclaimed water at relatively high concentrations corroborating the fact that PPCPs do not significantly partition to mineral phases. An online SPE-HPLC-APPI-MS/MS method and an online SPE-HPLC-HESI-MS/MS method were developed to analyze reclaimed water and drinking water samples. In the reclaimed water study, reclaimed water samples were collected from the sprinkler for a year-long period at Florida International University Biscayne Bay Campus, where reclaimed water was reused for irrigation. Analysis results showed that several analytes were continuously detected in all reclaimed water samples. Coprostanol, bisphenol A and DEET's maximum concentration exceeded 10 μg/L (ppb). The four most frequently detected compounds were diphenhydramine (100%), DEET (98%), atenolol (98%) and carbamazepine (96%). In the study of drinking water, 54 tap water samples were collected from the Miami-Dade area. The maximum concentrations of salicylic acid, ibuprofen and DEET were 521 ng/L, 301 ng/L and 290 ng/L, respectively. The three most frequently detected compounds were DEET (93%), carbamazepine (43%) and salicylic acid (37%), respectively. Because the source of drinking water in Miami-Dade County is the relatively pristine Biscayne aquifer, these findings suggest the presence of wastewater intrusions into the delivery system or the onset of direct influence of surface waters into the shallow aquifer.

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The dissertation consists of three chapters related to the low-price guarantee marketing strategy and energy efficiency analysis. The low-price guarantee is a marketing strategy in which firms promise to charge consumers the lowest price among their competitors. Chapter 1 addresses the research question "Does a Low-Price Guarantee Induce Lower Prices'' by looking into the retail gasoline industry in Quebec where there was a major branded firm which started a low-price guarantee back in 1996. Chapter 2 does a consumer welfare analysis of low-price guarantees to drive police indications and offers a new explanation of the firms' incentives to adopt a low-price guarantee. Chapter 3 develops the energy performance indicators (EPIs) to measure energy efficiency of the manufacturing plants in pulp, paper and paperboard industry.

Chapter 1 revisits the traditional view that a low-price guarantee results in higher prices by facilitating collusion. Using accurate market definitions and station-level data from the retail gasoline industry in Quebec, I conducted a descriptive analysis based on stations and price zones to compare the price and sales movement before and after the guarantee was adopted. I find that, contrary to the traditional view, the stores that offered the guarantee significantly decreased their prices and increased their sales. I also build a difference-in-difference model to quantify the decrease in posted price of the stores that offered the guarantee to be 0.7 cents per liter. While this change is significant, I do not find the response in comeptitors' prices to be significant. The sales of the stores that offered the guarantee increased significantly while the competitors' sales decreased significantly. However, the significance vanishes if I use the station clustered standard errors. Comparing my observations and the predictions of different theories of modeling low-price guarantees, I conclude the empirical evidence here supports that the low-price guarantee is a simple commitment device and induces lower prices.

Chapter 2 conducts a consumer welfare analysis of low-price guarantees to address the antitrust concerns and potential regulations from the government; explains the firms' potential incentives to adopt a low-price guarantee. Using station-level data from the retail gasoline industry in Quebec, I estimated consumers' demand of gasoline by a structural model with spatial competition incorporating the low-price guarantee as a commitment device, which allows firms to pre-commit to charge the lowest price among their competitors. The counterfactual analysis under the Bertrand competition setting shows that the stores that offered the guarantee attracted a lot more consumers and decreased their posted price by 0.6 cents per liter. Although the matching stores suffered a decrease in profits from gasoline sales, they are incentivized to adopt the low-price guarantee to attract more consumers to visit the store likely increasing profits at attached convenience stores. Firms have strong incentives to adopt a low-price guarantee on the product that their consumers are most price-sensitive about, while earning a profit from the products that are not covered in the guarantee. I estimate that consumers earn about 0.3% more surplus when the low-price guarantee is in place, which suggests that the authorities should not be concerned and regulate low-price guarantees. In Appendix B, I also propose an empirical model to look into how low-price guarantees would change consumer search behavior and whether consumer search plays an important role in estimating consumer surplus accurately.

Chapter 3, joint with Gale Boyd, describes work with the pulp, paper, and paperboard (PP&PB) industry to provide a plant-level indicator of energy efficiency for facilities that produce various types of paper products in the United States. Organizations that implement strategic energy management programs undertake a set of activities that, if carried out properly, have the potential to deliver sustained energy savings. Energy performance benchmarking is a key activity of strategic energy management and one way to enable companies to set energy efficiency targets for manufacturing facilities. The opportunity to assess plant energy performance through a comparison with similar plants in its industry is a highly desirable and strategic method of benchmarking for industrial energy managers. However, access to energy performance data for conducting industry benchmarking is usually unavailable to most industrial energy managers. The U.S. Environmental Protection Agency (EPA), through its ENERGY STAR program, seeks to overcome this barrier through the development of manufacturing sector-based plant energy performance indicators (EPIs) that encourage U.S. industries to use energy more efficiently. In the development of the energy performance indicator tools, consideration is given to the role that performance-based indicators play in motivating change; the steps necessary for indicator development, from interacting with an industry in securing adequate data for the indicator; and actual application and use of an indicator when complete. How indicators are employed in EPA’s efforts to encourage industries to voluntarily improve their use of energy is discussed as well. The chapter describes the data and statistical methods used to construct the EPI for plants within selected segments of the pulp, paper, and paperboard industry: specifically pulp mills and integrated paper & paperboard mills. The individual equations are presented, as are the instructions for using those equations as implemented in an associated Microsoft Excel-based spreadsheet tool.

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This study was conducted to evaluate the inclusion of two levels (2.5 e 5.0%) of dried yeast (Saccharomyces cerevisiae) and its by-products, disrupted yeast cells and yeast cell wall in diets for juveniles of pacu (Piaractus mesopotamicus). Production performance, body and plasmatic composition indexes were evaluated. Seven isoproteic (26% digestible protein) and isoenergetic (3.100 kcal digestible energy) diets were formulated containing increased levels of each ingredient. The diets were supplied for 86 days, "ad libitum". Yeast and by-products increase feed efficiency and protein use, when compared to the control diet. Carcass composition and plasmatic (glucose, cortisol, uric acid, urea and plasmatic protein) levels are not affected by the test ingredient supplementation.

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Ceriporiopsis subvermispora is a promising white-rot fungus for biopulping. However, the underlying biochemistry involved in lignin removal and insignificant cellulose degradation by this species is not completely understood. This paper addresses this topic focusing on the involvement of ethanol-soluble extractives and wood transformation products in the biodegradation process. Cultures containing ethanol-extracted or in natura wood chips presented similar levels of extracellular enzymes and degradation of wood components. Fe3+-reducing compounds present in undecayed Pinus taeda were rapidly diminished by fungal degradation. Lignin-degradation products released during biodegradation restored part of the Fe3+-reducing activity. However, Fe3+ reduction was ineffective in presence of 0.5 mM oxalate at pH 4.5. Fungal consumption of Fe3+-reducing compounds and secretion of oxalic acid minimized the significance of Fenton`s reaction in the initial stages of wood biotreatment. This would explain limited polysaccharide degradation by the fungus that also lacks a complete set of hydrolytic enzymes. Scientific relevance of the paper: Ceriporiopsis subvermispora is a white-rot fungus suitable for biopulping processes because it degrades lignin selectively and causes significant structural changes on the wood components during the earlier decay stages. However, the intricate mechanism to explain lignin transformation and insignificant cellulose degradation by this species remains poorly understood. Some recent evidences pointed out for lipid peroxidation reactions as all initiating process explaining lignin degradation. On the other hand, alkylitaconic acids produced by the fungus via transformations of fatty acids occurring in wood showed to prevent polysaccharide degradation in Fenton reactions. In this context, one may conclude that the involvement of native wood substances or their transformation products in the overall wood biodegradation process induced by C subvermispora is still a matter of discussion. While free and esterified fatty acids present in wood extractives may be involved in the biosynthesis of alkylitaconic acids and in lipid peroxidation reactions, some extractives and lignin degradation products can reduce Fe3+, providing Fe2+ species needed to form OH radical via Fenton`s reaction. The present study focuses on this topic by evaluating the relevance of ethanol-soluble extractives and wood transformation products on the biodegradation of P. taeda by C subvermispora. For this, solid-state cultures containing ethanol-extracted and in natura wood chips were evaluated in details for up to 4 weeks. (C) 2007 Elsevier Ltd. All rights reserved.

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Blends of canola oil (CO) and fully hydrogenated cottonseed oil (FHCSO), with 20, 25, 30, 35 and 40% FHCSO (w/w) were interesterified under the following conditions: 0.4% sodium methoxide, 500 rpm stirring, 100C, 20 min. The original and interesterified blends were examined for triacylglycerol composition, melting point, solid fat content (SFC) and consistency. Interesterification caused considerable rearrangement of triacylglycerol species, reduction of trisaturated triacylglycerol content and increase in disaturated-monounsaturated and monosaturated-diunsaturated triacylglycerols in all blends, resulting in lowering of respective melting points. The interesterified blends showed reduced SFC at all temperatures and more linear melting profiles if compared with the original blends. Consistency, expressed as yield value, significantly decreased after the reaction. Iso-solid curves indicated eutectic interactions for the original blends, which were eliminated after randomization. The 80:20, 75:25, 70:30 and 65:35 (w/w) CO: FHCSO interesterified blends showed characteristics which are appropriate for their application as soft margarines, spreads, fat for bakery/all-purpose shortenings, and icing shortenings, respectively. PRACTICAL APPLICATIONS Recently, a number of studies have suggested a direct relationship between trans isomers and increased risk of vascular disease. In response, many health organizations have recommended reducing consumption of foods containing trans fatty acids. In this connection, chemical interesterification has proven the main alternative for obtaining plastic fats that have low trans isomer content or are even trans isomer free. This work proposes to evaluate the chemical interesterification of binary blends of canola oil and fully hydrogenated cottonseed oil and the specific potential application of these interesterified blends in food products.

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First of all, we would like to clarify that the passive to active transition was determined not by using Solgasmix [1], but by combining thermodynamic equilibrium and mass balance for the oxidation of SiC under pure CO2 and pure CO. The model used in our paper [2]was an extension ofWagner’s model [3], in a similar way as Balat et al. [4] did for the oxidation of SiC in oxygen.