1,622 research outputs found
A Kalina Cycle Application for Power Generation
A multi-component (NB3/H2O) Kalina-type cycle that utilizes the exhaust from a gas turbine is investigaed in this paper. The turbine-inlet pressure of 5.96 × 106N/m2 and temperature of 755.372 K were kept constant, as well as the working fluid temperature at the condenser outlet (at 290K). The HN3 mass fraction at the turbine inlet was varied along with the seperator temperature and the effects on the cycle efficiency were studied. The relationships between turbine-inlet flow and the seperator-inlet. How are shown in addition to the upper and lower HN3 mass-fraction bounds. The multi-component working-fluid cycle investigated is 10–20% more efficient than a Rankine cycle with the same boundary conditions
Engineering model system study for a regenerative fuel cell: Study report
Key design issues of the regenerative fuel cell system concept were studied and a design definition of an alkaline electrolyte based engineering model system or low Earth orbit missions was completed. Definition of key design issues for a regenerative fuel cell system include gaseous reactant storage, shared heat exchangers and high pressure pumps. A power flow diagram for the 75 kW initial space station and the impact of different regenerative fuel cell modular sizes on the total 5 year to orbit weight and volume are determined. System characteristics, an isometric drawing, component sizes and mass and energy balances are determined for the 10 kW engineering model system. An open loop regenerative fuel cell concept is considered for integration of the energy storage system with the life support system of the space station. Technical problems and their solutions, pacing technologies and required developments and demonstrations for the regenerative fuel cell system are defined
When two worlds collide: A story about collaboration, witnessing and life story research with soldiers returning from war
The story we share here stems from our research with British military personnel who are adapting to life with a physical and/or psychological disability after serving in the Iraq or Afghanistan wars. Throughout our research, we have struggled to answer the kinds of questions that plague qualitative researchers: How might we gain insights into intense, traumatic, even life-changing experiences? Should we be inviting individuals to recount or revisit such potent moments from their lives? What interpretive framework might we draw on to make sense of what are sometimes senseless experiences? How can we share any ensuing understanding with others without diluting, diminishing or disrespecting the lives of soldiers or their families? The story we share here – which responds to Denzin’s (2003) challenge to reanimate life and Erickson’s (2010) provocation to do so with greater modesty, visibility, and reflexivity – offers one answer to these questions
Endurance Test and Evaluation of Alkaline Water Electrolysis Cells
The overall objective of this program is to assess the state of alkaline water electrolysis cell technology and its potential as part of a Regenerative Fuel Cell System (RFCS) of a multikilowatt orbiting powerplant. The program evaluates the endurance capabilities of alkaline electrolyte water electrolysis cells under various operating conditions, including constant condition testing, cyclic testing and high pressure testing. The RFCS demanded the scale-up of existing cell hardware from 0.1 sq ft active electrode area to 1.0 sq ft active electrode area. A single water electrolysis cell and two six-cell modules of 1.0 sq ft active electrode area were designed and fabricated. The two six-cell 1.0 sq ft modules incorporate 1.0 sq ft utilized cores, which allow for minimization of module assembly complexity and increased tolerance to pressure differential. A water electrolysis subsystem was designed and fabricated to allow testing of the six-cell modules. After completing checkout, shakedown, design verification and parametric testing, a module was incorporated into the Regenerative Fuel Cell System Breadboard (RFCSB) for testing at Life Systems, Inc., and at NASA JSC
Separating Proactive Conservation from Species Listing Decisions
Proactive Conservation is a paradigm of natural resource management in the United States that encourages voluntary, collaborative efforts to restore species before they need to be protected through government regulations. This paradigm is widely used to conserve at-risk species today, and when used in conjunction with the Policy for Evaluation of Conservation Efforts (PECE), it allows for successful conservation actions to preclude listing of species under the Endangered Species Act (ESA). Despite the popularity of this paradigm, and recent flagship examples of its use (e.g., greater sage grouse, Centrocercus urophasianus), critical assessments of the outcomes of Proactive Conservation are lacking from the standpoint of species status and recovery metrics. Here, we provide such an evaluation, using the New England cottontail (Sylvilagus transitionalis), heralded as a success of Proactive Conservation efforts in the northeastern United States, as a case study. We review the history and current status of the species, based on the state of the science, in the context of the Conservation Initiative, and the 2015 PECE decision not to the list the species under the ESA. In addition to the impacts of the PECE decision on the New England cottontail conservation specifically, our review also evaluates the benefits and limits of the Proactive Conservation paradigm more broadly, and we make recommendations for its role in relation to ESA implementation for the future of at-risk species management. We find that the status and assurances for recovery under the PECE policy, presented at the time of the New England cottontail listing decision, were overly optimistic, and the status of the species has worsened in subsequent years. We suggest that use of PECE to avoid listing may occur because of the perception of the ESA as a punitive law and a misconception that it is a failure, although very few listed species have gone extinct. Redefining recovery to decouple it from delisting and instead link it to probability of persistence under recommended conservation measures would remove some of the stigma of listing, and it would strengthen the role of Species Status Assessments in endangered species conservation
Dynamics of findings of non-specific resistance in the mouth cavity in children with lesions of the mucous membrane epithelium of the mouth cavity against acute lymphoblastic leukemia in the treatment process.
There was conducted study of dynamics of findings of non-specific resistance in the mouth cavity in children with lesions of the mucous membrane epithelium of the mouth cavity against acute lymphoblastic leukemia in the treatment process by authors-developed methods. It is known that in children with leukemia immunodeficiency states develop immunological disorders resulted from treatment with cytotoxic drugs. Moreover, not only general, but also the local immunity of the mouth cavity suffers, which is accompanied by development of infectious processes in the tissues that perform the barrier function, which include mucous membrane epithelium of the mouth cavity. A key role in the system of antimicrobial protection of the mouth cavity is performed by mucolytic enzyme lisocyme and α-defensins (HNP 1-3). 76 children with acute lymphoblastic leukemia aged from 2 to 18 years suffering from such dental diseases as generalized chronic catarrhal gingivitis, erosive-ulcerative and candidal stomatitis took part in the clinical study. All children under clinical study were divided into 2 groups - the main and comparison. Standard protocol treatment was used in the comparison group. Developed treatment-and-prophylactic complex was used in the main group. The children of the main group were prescribed developed treatment-and-prophylactic complex depending on the period of the disease: the first version of local treatment was used in the acute period and the relapse of the disease, the second - in the period of remission. The results of research have shown a stimulating effect of therapeutic and prophylactic measures on the natural antimicrobial system of mouth cavity protection, both in children of the main groups under study and in the comparison groups. Such a phenomenon should be considered as a positive process that contributes to the increase of resistance in periodontal tissues and mucous membrane epithelium of the mouth cavity
Mesozoic intraplate granitic magmatism in the Altai accretionary orogen, NW China: implications for the orogenic architecture and crustal growth
The Central Asian Orogenic Belt (CAOB) is the world's largest Phanerozoic accretionary orogen and is the most important site for juvenile crustal growth in the Phanerozoic. In this work, we employed U-Pb zircon geochronology to identify the early and middle Mesozoic intraplate granitic intrusive events in the Chinese Altai segment of the southern CAOB in order to better understand the crustal architecture of the CAOB. We also used whole-rock geochemical, Sr-Nd isotopic and zircon Hf isotopic data to constrain the generation for these granitic rocks and to evaluate the implications for vertical crustal growth in this region. The Early Mesozoic granitic intrusions were emplaced between 220 and 200 Ma in the central Altai “microcontinental terrane” (also widely referred to as Units 2 and 3). The granites have shoshonitic and high-K calc-alkaline affinities and show the characteristics of differentiated I-type granite. The whole-rock initial 87Sr/86Sr ratios (0.7058-0.7128) and εNd(210) values (−0.6 to −4.3), as well as the zircon εHf(t) values (−4.0 to +5.0) and two-stage Hf model ages (0.94-1.52 Ga), suggest that the granitic magmas were produced from a mixed source with both mantle-derived and recycled crustal components. The middle Mesozoic granites were emplaced at ~150 Ma in the southern Altai “accretionary terrane” (Units 4 and 5). They show A-type characteristics with the REE tetrad effect and have positive εNd(151) whole-rock values of +1.0 to +5.2 and two-stage Nd model ages (TDM2) of 0.6 to 1.0 Ga. Zircon Hf data show positive zircon εHf(151) values of +1 to +8 and two-stage Hf model ages of 0.6 to 1.2 Ga. The Nd-Hf isotopic data suggest that the granitic magmas were derived from short-lived juvenile mantle-derived materials. Thus, the isotopic signatures of all the Mesozoic granites from the central (old terrane) and southern (young accretional terrane) Altai suggest that the basement of both terranes has retained its original nature. The data further imply that the Altai orogen has kept its original architecture of Paleozoic horizontal accretion during Mesozoic time, as commonly observed in accretionary orogens where horizontal tectonics are dominant. All the early Mesozoic intrusions in the Altai were emplaced in an intraplate anorogenic setting; hence are distinguished from the contemporaneous syn- or post-orogenic magmatism in the eastern CAOB. We conclude that the early Mesozoic granites in the CAOB were emplaced in a variety of tectonic settings
EARLY NEOPROTEROZOIC CRUST FORMATON IN THE DZABKHAN MICROCONTINENT, CENTRAL ASIAN OROGENIC BELT
The Dzabkhan microcontinent was defined by [Mossakovsky et al., 1994] as a cratonic terrane with an early Precambrian basement that combines highgrade metamorphic complexes of the Songino, Dzabkhan, Otgon, Baidarik, Ider and Jargalant Blocks. However, early Precambrian ages have so far only been recognized in the Baidarik and Ider blocks [Kozakov et al., 2007, 2011; Kröner et al., 2015].The Dzabkhan microcontinent was defined by [Mossakovsky et al., 1994] as a cratonic terrane with an early Precambrian basement that combines highgrade metamorphic complexes of the Songino, Dzabkhan, Otgon, Baidarik, Ider and Jargalant Blocks. However, early Precambrian ages have so far only been recognized in the Baidarik and Ider blocks [Kozakov et al., 2007, 2011; Kröner et al., 2015]
Comparison of Commercial and Self-Initiated Weight Loss Programs in People With Prediabetes: A Randomized Control Trial
To determine if a widely available weight-management program (Weight Watchers) could achieve sufficient weight loss in persons with prediabetes compared with a Diabetes Prevention Program-based individual counseling program supported by National Diabetes Education Program materials.
METHODS:
We conducted an individual, randomized intervention trial in Indianapolis, Indiana, in 2013 to 2014, in 225 persons with prediabetes. We compared the Weight Watchers weight-management program (n = 112) with Your Game Plan to Prevent Type 2 Diabetes, a program developed by the National Diabetes Education Program. Outcomes were weight and metabolic markers measured at baseline, 6 months, and 12 months.
RESULTS:
Intervention participants lost significantly more weight than controls at 6 months (5.5% vs 0.8%) and 12 months (5.5% vs 0.2%; both P < .001). The intervention group also had significantly greater improvements in hemoglobin A1c and high-density lipoprotein cholesterol level than did controls.
CONCLUSIONS:
A large weight-management program is effective for achieving lifestyle changes associated with diabetes prevention. Such programs could significantly increase the availability of diabetes prevention programs worldwide making an immediate and significant public health impact
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