1,162 research outputs found
Nickel hydrogen bipolar battery electrode design
The preferred approach of the NASA development effort in nickel hydrogen battery design utilizes a bipolar plate stacking arrangement to obtain the required voltage-capacity configuration. In a bipolar stack, component designs must take into account not only the typical design considerations such as voltage, capacity and gas management, but also conductivity to the bipolar (i.e., intercell) plate. The nickel and hydrogen electrode development specifically relevant to bipolar cell operation is discussed. Nickel oxide electrodes, having variable type grids and in thicknesses up to .085 inch are being fabricated and characterized to provide a data base. A selection will be made based upon a system level tradeoff. Negative (hydrpogen) electrodes are being screened to select a high performance electrode which can function as a bipolar electrode. Present nickel hydrogen negative electrodes are not capable of conducting current through their cross-section. An electrode was tested which exhibits low charge and discharge polarization voltages and at the same time is conductive. Test data is presented
High inclination orbits in the secular quadrupolar three-body problem
The Lidov-Kozai mechanism allows a body to periodically exchange its
eccentricity with inclination. It was first discussed in the framework of the
quadrupolar secular restricted three-body problem, where the massless particle
is the inner body, and later extended to the quadrupolar secular nonrestricted
three body problem. In this paper, we propose a different point of view on the
problem by looking first at the restricted problem where the massless particle
is the outer body. In this situation, equilibria at high mutual inclination
appear, which correspond to the population of stable particles that Verrier &
Evans (2008,2009) find in stable, high inclination circumbinary orbits around
one of the components of the quadruple star HD 98800. We provide a simple
analytical framework using a vectorial formalism for these situations. We also
look at the evolution of these high inclination equilibria in the non
restricted case.Comment: 11 pages, 6 figures. Accepted by MNRAS 2009 September 1
Untangling the socio-political knots: A systems view on Indonesia's inclusive energy transitions
National energy transitions face complex socio-political challenges, ranging from inertia to exacerbated inequalities. There are limited studies investigating these dimensions, especially in developing economies. This paper presents Indonesia, a country with high fossil fuel dependency, as a valuable case study to investigate the societal interplay affecting transitions. Interviews and literature analyses were conducted to assess barriers and levers to success. The findings are further analysed with systems thinking (ST), highlighting dynamic patterns and interdependencies. It is found that conflicting interests, inconsistent regulation, and low capability at the implementation level are among the most persistent barriers creating disparities between intentions and reality. These leave some groups disproportionately disadvantaged; notably, regions with fossil fuel-dependent income, informal sectors, and indigenous and local communities. Recommendations include the creation of an independent agency for the energy transition, and empowering regional participation. Addressing inclusion is imperative for social justice as well as to ensure adoptability and acceptance from all
Platelet lysate as a serum substitute for 2D static and 3D perfusion culture of stromal vascular fraction cells from human adipose tissue
Fetal bovine serum (FBS) and fibroblast growth factor (FGF)-2 are key supplements for the culture of stromal vascular fraction (SVF) cells from adipose tissue, both for typical monolayer (2D) expansion and for streamlined generation of osteogenic-vasculogenic grafts in 3D perfusion culture. The present study investigates whether factors present in human platelet lysate (PL) could substitute for FBS and FGF-2 in 2D and 3D culture models of SVF cells from human lipoaspirates. SVF cells were grown in medium supplemented with 10% FBS+FGF-2 or with 5% PL. In 2D cultures, PL initially supported SVF cell proliferation, but resulted in growth arrest shortly after the first passage. Freshly isolated SVF cells cultured with both media under perfusion for 5 days within 3D ceramic scaffolds induced bone formation after subcutaneous implantation in nude mice. However, blood vessels of donor origin were generated only using FBS+FGF-2-cultured cells. This was unexpected, because the proportion of CD34+/CD31+ endothelial lineage cells was significantly higher with PL than that of FBS+FGF-2 (33% vs. 3%, respectively). These results support the use of PL as a substitute of FBS+FGF-2 for short-term culture of human SVF cells, and indicate that more specific serum-free formulations are required to maintain a functionally vasculogenic fraction of SVF cells expanded under 3D perfusion
Impact of the use of cryobank samples in a selected cattle breed: a simulation study
<p>Abstract</p> <p>Background</p> <p>High selection pressure on domestic cattle has led to an undesirable increase in inbreeding, as well as to the deterioration of some functional traits which are indirectly selected. Semen stored in a cryobank may be a useful way to redirect selection or limit the loss of genetic diversity in a selected breed. The purpose of this study was to analyse the efficiency of current cryobank sampling methods, by investigating the benefits of using cryopreserved semen in a selection scheme several generations after the semen was collected.</p> <p>Methods</p> <p>The theoretical impact of using cryopreserved semen in a selection scheme of a dairy cattle breed was investigated by simulating various scenarios involving two negatively correlated traits and a change in genetic variability of the breed.</p> <p>Results</p> <p>Our results indicate that using cryopreserved semen to redirect selection will have an impact on negatively selected traits only if it is combined with major changes in selection objectives or practices. If the purpose is to increase genetic diversity in the breed, it can be a viable option.</p> <p>Conclusions</p> <p>Using cryopreserved semen to redirect selection or to improve genetic diversity should be carried out with caution, by considering the pros and cons of prospective changes in genetic diversity and the value of the selected traits. However, the use of genomic information should lead to more interesting perspectives to choose which animals to store in a cryobank and to increase the value of cryobank collections for selected breeds.</p
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New combinations for Sonoran Desert plants
We provide new nomenclatural combinations for three Sonoran Desert plants: Opuntia
engelmannii var. laevis (J.M. Coulter) Felger, Verrier, & Carnahan, comb. nov.; Parkinsonia
florida subsp. peninsulare (Rose) Hawkins & Felger, comb. nov.; and Parkinsonia ×sonorae (Rose
& I.M. Johnston ex I.M. Johnston) Hawkins & Felger, comb. nov
Symptom Burden, Medication Detriment, and Support for the Use of the 15D Health-Related Quality of Life Instrument in a Chronic Pain Clinic Population
Chronic noncancer pain is a prevalent problem associated with poor quality of life. While symptom burden is frequently mentioned in the literature and clinical settings, this research highlights the considerable negative impact of chronic pain on the individual. The 15D, a measure of health-related quality of life (HRQOL), is a user-friendly tool with good psychometric properties. Using a modified edmonton symptom assessment scale (ESAS), we examined whether demographics, medical history, and symptom burden reports from the ESAS would be related statistically to HRQOL measured with the 15D. Symptom burden, medication detriment scores, and number of medical comorbidities were significant negative predictors of 15D scores with ESAS symptom burden being the strongest predictor. Our findings highlight the tremendous symptom burden experienced in our sample. Our data suggest that heavier prescription medication treatment for chronic pain has the potential to negatively impact HRQOL. Much remains unknown regarding how to assess and improve HRQOL in this relatively heterogeneous clinical population
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