排序方式: 共有26条查询结果,搜索用时 16 毫秒
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Ricardo Garcia-Padron Dan Loyd Stefan Sjökvist 《Subsurface Sensing Technologies and Applications》2002,3(2):125-150
One promising method of locating buried objects, such as land mines, is to use optical systems for detecting contrasts in surface temperature. With enhanced knowledge about the interacting physical processes behind these temperature contrasts, it is possible to improve detection precision. In such a context, moisture movement in the soil and moisture evaporation from the surface have been found to be of particular interest. This study was based on indoor experiments on wet and dry sand exposed to radiation from a solar panel. Simulations of heat and moisture transfer conducted with a one-dimensional model are also presented for the experiments. The calculations were successful in accurately predicting surface temperatures for both wet and dry sand, making it possible to predict surface temperatures under different conditions. These findings will contribute to increasing the probability of successful detection of buried objects under real conditions using optical methods. 相似文献
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Andre Matthew Loyd Roger W. Nightingale Yin Song Jason F. Luck Hattie Cutcliffe Barry S. Myers Cameron ‘Dale’ Bass 《Accident; analysis and prevention》2014
Given the high incidence of TBI, head injury has been studied extensively using both cadavers and anthropomorphic test devices (ATDs). However, few studies have benchmarked the response of ATD heads against human data. Hence, the objective of this study is to investigate the response of adult and ATD heads in impact, and to compare adult Hybrid III head responses to the adult head responses. 相似文献
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IM Robbins EV Colvin TP Doyle WE Kemp JE Loyd WS McMahon GN Kay 《Canadian Metallurgical Quarterly》1998,98(17):1769-1775
BACKGROUND: This report describes the complication of pulmonary vein stenosis with resultant severe pulmonary hypertension that developed in 2 patients after successful catheter ablation of chronic atrial fibrillation. METHODS AND RESULTS: Three months after successful catheter ablation of atrial fibrillation, both patients developed progressive dyspnea and pulmonary hypertension. Both were found to have severe stenosis of all 4 pulmonary veins near the junction with the left atrium. Balloon dilation of the stenotic pulmonary veins was performed in these patients, with improvement in dyspnea and pulmonary hypertension. CONCLUSIONS: The complication of pulmonary vein stenosis is potentially life-threatening, and the application of radiofrequency current within the pulmonary veins with standard catheter technology should be avoided. This complication can be treated with balloon dilation, although the long-term course is unknown. 相似文献
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Meliopoulos A.P. Glysis E.N. Loyd R.E. Horton P.B. 《Industry Applications, IEEE Transactions on》1999,35(3):525
The authors of “Performance evaluation of steel-conduit-enclosed power systems” (see ibid., vol. 35, no. 3, p. 515-23, 1999) respond to the comments on the original paper. They argue that the intention of their paper is that the users should use the proper value of overcurrent device rating as it will be dictated by the application 相似文献
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The strong influence of the oxide support upon the turn-over frequency (TOF) of methanol oxidation over supported metal oxide catalysts has been well documented in recent years. However, the mechanistic origins (adsorption equilibrium of methanol to methoxy species, rate-determining methoxy surface decomposition, or product desorption equilibrium) of this interesting phenomenon are not completely understood. In order to obtain additional insight, the steady-state surface concentrations of adsorbed methoxy intermediates on monolayer catalysts (8 V atoms nm−2) of V2O5/(TiO2, CeO2, Al2O3 and ZrO2) have been quantified with in situ transmission infrared spectroscopy/mass spectrometry. Calculations of the adsorption equilibrium constant, Kads, show a six times increase for vanadia on oxide supports of Al < Ti < Zr < Ce, whereas the methoxy surface decomposition rate constant, krds (rds = rate-determining step), shows a 22 times increase in value over these same catalysts. Thus, changes in both the adsorption equilibrium and the methoxy decomposition properties of supported metal oxide catalysts appear to be responsible for the support effect, although the methoxy decomposition is clearly the reaction step that is more sensitive to the specific metal oxide support. More fundamentally, the support effect appears to correlate with the electronegativity of the support cation, which is proposed to have influence upon the rate of methoxy decomposition through hydride abstraction and on the steady-state equilibrium adsorption capacity of methanol to surface methoxy intermediates through the basicity of the bridging V–O–support bond (the adsorption site). 相似文献
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The application of in situ Raman, IR, and UV-Vis DRS spectroscopies during steady-state methanol oxidation has demonstrated
that the molecular structures of surface vanadium oxide species supported on metal oxides are very sensitive to the coordination
and H-bonding effects of adsorbed methoxy surface species. Specifically, a decrease in the intensity of spectral bands associated
with the fully oxidized surface (V5+) vanadia active phase occurred in all three studied spectroscopies during methanol oxidation. The terminal V = O (∼1030 cm−1) and bridging V–O–V (∼900–940 cm−1) vibrational bands also shifted toward lower frequency, while the in situ UV-Vis DRS spectra exhibited shifts in the surface
V5+ LMCT band (>25,000 cm−1) to higher edge energies. The magnitude of these distortions correlates with the concentration of adsorbed methoxy intermediates
and is most severe at lower temperatures and higher methanol partial pressures, where the surface methoxy concentrations are
greatest. Conversely, spectral changes caused by actual reductions in surface vanadia (V5+) species to reduced phases (V3+/V4+) would have been more severe at higher temperatures. Moreover, the catalyst (vanadia/silica) exhibiting the greatest shift
in UV-Vis DRS edge energy did not exhibit any bands from reduced V3+/V4+ phases in the d–d transition region (10,000–30,000 cm−1), even though d–d transitions were detected in vanadia/alumina and vanadia/zirconia catalysts. Therefore, V5+ spectral signals are generally not representative of the percent vanadia reduction during the methanol oxidation redox cycle,
although estimates made from the high temperature, low methoxy surface coverage IR spectra suggest that the catalyst surfaces
remain mostly oxidized during steady-state methanol oxidation (15–25% vanadia reduction). Finally, adsorbed surface methoxy
intermediate species were easily detected with in situ IR spectroscopy during methanol oxidation in the C–H stretching region
(2800–3000 cm−1) for all studied catalysts, the vibrations occurring at different frequencies depending on the specific metal oxide upon
which they chemisorb. However, methoxy bands were only found in a few cases using in situ Raman spectroscopy due to the sensitivity
of the Raman scattering cross-sections to the specific substrate onto which the surface methoxy species are adsorbed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Jeffrey Comer Molly Bassette Riley Burghart Mayme Loyd Susumu Ishiguro Ettayapuram Ramaprasad Azhagiya Singam Ariela Vergara-Jaque Ayaka Nakashima Kengo Suzuki Brian V. Geisbrecht Masaaki Tamura 《International journal of molecular sciences》2021,22(6)
Beta glucans are known to have immunomodulatory effects that mediated by a variety of mechanisms. In this article, we describe experiments and simulations suggesting that beta-1,3 glucans may promote activation of T cells by a previously unknown mechanism. First, we find that treatment of a T lymphoblast cell line with beta-1,3 oligoglucan significantly increases mRNA levels of T cell activation-associated cytokines, especially in the presence of the agonistic anti-CD3 antibody. This immunostimulatory activity was observed in the absence of dectin-1, a known receptor for beta-1,3 glucans. To clarify the molecular mechanism underlying this activity, we performed a series of molecular dynamics simulations and free-energy calculations to explore the interaction of beta-1,3 oligoglucans with potential immune receptors. While the simulations reveal little association between beta-1,3 oligoglucan and the immune receptor CD3, we find that beta-1,3 oligoglucans bind to CD28 near the region identified as the binding site for its natural ligands CD80 and CD86. Using a rigorous absolute binding free-energy technique, we calculate a dissociation constant in the low millimolar range for binding of 8-mer beta-1,3 oligoglucan to this site on CD28. The simulations show this binding to be specific, as no such association is computed for alpha-1,4 oligoglucan. This study suggests that beta-1,3 glucans bind to CD28 and may stimulate T cell activation collaboratively with T cell receptor activation, thereby stimulating immune function. 相似文献
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Samples of 16-ply, quasi-isotropic bismaleimide composites were aged in convection ovens at 150°C, 177°C, and 204°C for up to 16,000 hours. As a measure of degradation, transverse microcrack density was characterized as a function of time, temperature, and ply depth. Times required to reach onset and saturation crack density were delayed on the tool side of the laminate, for lower temperatures, and for deeper ply depths. Saturation crack densities ranged from 35 cracks/cm to 46 cracks/cm, depending on ply depth. Master curves were constructed for each ply level to express all time-temperature data for that ply as a single reference curve. A mass transfer analysis further suggests that diffusion is the controlling mechanism in the degradation process. Finally, a prediction of the degradation behavior in the 120,000-h lifetime of the HSCT aircraft for a sustained temperature of 150°C indicates that ∼13 plies will have reached initiation in a quasi-isotropic laminate. 相似文献