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61.
Stearic acid is one of five major fatty acids found in soybean oil. It is a fully saturated lipid and is known for neutral or positive effects on LDL cholesterol when consumed by humans. Unfortunately, stearic acid only accounts for about 4% of the total seed oil produced in commodity soybean. Previous work has shown that stearic acid can reach levels as high as 28% of the total oil fraction when the SACPD-C gene, encoding the delta-9-stearoyl-acyl carrier protein desaturase responsible for most of the stearic acid variation in soybean seed, is ablated in combination with other loci. In order to increase stearic acid content and create soybeans with improved utility based on fatty acid composition, we combined mutations in SACPD-C with other mutations in the fatty acid biosynthetic pathway. Soybean plants carrying mutant alleles of both SACPD-C and FAD2-1A produce seed with stearic acid levels from 14% to 21%, and with elevated levels of oleic acid. Soybeans carrying mutations in both SACPD-C and FAD3A or FAD3C have both statistically significantly elevated levels of stearic acid (from 15–21%) and statistically reduced linolenic acid levels. Neither mutant combination appears to affect other agronomic properties such as plant morphology or seed protein levels making this a potentially viable trait.  相似文献   
62.
In this study, blend membranes based on a combination of sulfonated poly (styrene-isobutylene-styrene) (SIBS) with isopentylamine (IPA) were synthetized as potential candidates for direct methanol fuel cell (DMFC) applications. The impact of sulfonation level (57–93 mol%) and percentage of IPA incorporation (1, 3, and 5 wt%) were analyzed via different properties of the resulting membrane. FTIR analysis showed that IPA was successfully incorporated into the sulfonated polymer matrix and also confirmed the interaction between the sulfonic and amine groups. This interaction generates significant morphological changes in the nanostructure of the membranes that are evident through results of small angle x-ray scattering and atomic force microscopy analysis. Proton conductivity and methanol permeability of the membranes were also analyzed. Proton conductivity was significantly enhanced with the incorporation of IPA at an optimum loading, creating additional paths for the conduction of protons through the membrane. It was also sensitive to the morphological changes produced after the IPA incorporation and the interconnection between the ionic domains. Methanol permeability increased slightly due to the additional water domains and the inability of the isopentyl groups of IPA to block the free-volume in the membrane. Despite this, the selectivity (proton conductivity over methanol permeability) of the membranes was comparable to the state-of-the-art Nafion®, especially at an optimum IPA incorporation of 3 wt%.  相似文献   
63.
The adherence of plasma sprayed NiCrAlY bond coats can be improved by an appropriate substrate surface finish. The interface fracture energy for crack propagation along the coating/substrate interface has been measured for different surface roughness by means of a specially designed four-point bending test. An increase of the interface fracture energy of about 15% was observed for a three times higher surface roughness. In addition, four-point bending tests with the coating on the side face of bending specimens were performed to analyze the fracture and spalling behavior of the coatings both under large tensile and compressive substrate deformations.  相似文献   
64.
Approximately 15 million cars and trucks reach the end of their useful life in the United States each year. More than 75% of the materials from end-of-life vehicles are profitably recovered and recycled by the private sector; automotive materials recycling is a success story. To achieve greater fuel efficiency and safety, today’s cars incorporate an increasing share of innovative light-weight materials. While these materials greatly enhance efficiency during vehicle use, they can present special challenges for recycling. These challenges will persist as automotive designs and the mix of materials used in vehicles continue evolving to further improve safety and performance. To meet the challenges of automotive materials recycling, the U.S. Department of Energy has recently expanded its collaborative research with industry in this area. This article discusses this collaborative government/industry approach to sustainable end-of-life vehicle recycling. For more information, contact Edward J. Daniels, Argonne National Laboratory, 9700 S. Cass Avenue, Building 362, Room C393, Argonne, IL 60439-4815; (630) 252-5279; fax (630) 252-1342; e-mail edaniels@anl.gov.  相似文献   
65.
Quantum dots (QDs) are increasingly the technology of choice for wide color gamut displays. Two popular options to incorporate QDs into displays include on‐edge and on‐surface solutions. The opto‐mechanical design for an on‐edge QD solution including a LED light bar (“on‐edge QD light bar”) is more complex than the design for a standard white phosphor LED light bar. In this paper, we identify and investigate a range of design parameters for an on‐edge QD light bar, and we show that these parameters have significant influence on system efficiency and color uniformity. The effects of varying these parameters are explored through the use of a custom adjustable testbed and optical raytracing methods. Our testbed data demonstrate the inherent trade‐offs between efficiency and color uniformity and provide guidance for the design of high‐performing displays. The optical raytracing data demonstrate a good predictive capability and support the use of optical modeling methods for a detailed exploration of a wider range of design parameters.  相似文献   
66.
67.
Nucleation in a supercooled or a supersaturated medium is a stochastic event, and hence statistical analyses are required for the understanding and prediction of such events. The development of reliable statistical methods for quantifying nucleation probability is highly desirable for applications where control of nucleation is required. The nucleation of gas hydrates in supercooled conditions is one such application. We describe the design and development of a high pressure automated lag time apparatus (HP-ALTA) for the statistical study of gas hydrate nucleation and growth at elevated gas pressures. The apparatus allows a small volume (≈150 μl) of water to be cooled at a controlled rate in a pressurized gas atmosphere, and the temperature of gas hydrate nucleation, T(f), to be detected. The instrument then raises the sample temperature under controlled conditions to facilitate dissociation of the gas hydrate before repeating the cooling-nucleation cycle again. This process of forming and dissociating gas hydrates can be automatically repeated for a statistically significant (>100) number of nucleation events. The HP-ALTA can be operated in two modes, one for the detection of hydrate in the bulk of the sample, under a stirring action, and the other for the detection of the formation of hydrate films across the water-gas interface of a quiescent sample. The technique can be applied to the study of several parameters, such as gas pressure, cooling rate and gas composition, on the gas hydrate nucleation probability distribution for supercooled water samples.  相似文献   
68.
This paper explores Canada's approach to water governance. It argues that fragmented governance has had negative impacts on Canada's ability to manage water resources adequately (particularly in the context of urbanization, agriculture and resource extraction), and to deal with new issues (such as climate change). Further, it argues that Canada's highly decentralized approach to water governance creates challenges of integration, coordination and data availability. The paper explores possible future strategies for innovations in water governance that may have the potential to improve water management outcomes.  相似文献   
69.
Abstract:

In this self‐study, the author gained in‐depth understanding of how to plan and implement problem‐based learning (PBL), a student‐centred approach to teaching and learning that is driven by messy, open‐ended problems. This paper focuses primarily on the issues and concerns that arose as she developed and implemented a modified form of traditional PBL (Barrows, 1996) in large, pre‐service science‐teacher education classes. To view the research from many perspectives, a variety of data collection methods and sources were used, including field notes, semi‐structured interviews, student‐generated documents, and student journals. The outcomes of this study describe challenges (problem development, facilitation of groups, and assessment) encountered by the author as she planned for and implemented PBL. Furthermore, changes in the author's classroom practice, the connection between these changes and constructivist learning principles, and implications for science‐teacher education are addressed.  相似文献   
70.
This paper is concerned with the elimination of unnecessary states in discrete-event system control agents. Several approaches to supervisor reduction are studied and a new relation between agents, comparability, is defined to encapsulate most of the concepts found in the aforementioned methods. This relation is also proven to be preserved under conjunction, which is commonly employed to determine the centralized representation of two decentralized DES supervisors.
Karen RudieEmail:
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