27,521 research outputs found
Performance of silicon solar cell assemblies
Solar cell assembly current-voltage characteristics, thermal-optical properties, and power performance were determined. Solar cell cover glass thermal radiation, optical properties, confidence limits, and temperature intensity effects on maximum power were discussed
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Fine-Scale Variations in Eucritic Pyroxene FeO/MnO: Process vs. Provenance.
Most asteroidal igneous rocks are eucrite-like basalts and gabbros, composed mostly of ferroan low- and high-Ca pyroxenes and calcic plagioclase, plus smaller amounts of silica (most commonly tridymite), ilmenite, chromite, troilite, Ca-phosphate, metal and sometimes ferroan olivine. Eucrite-like mafic rocks are fragments of the crusts of differentiated asteroids, and most are likely from 4 Vesta
Improved iron-tolerance in recycled aluminum alloys via direct strip casting process
Recycled aluminum alloys are pivotal for sustainable manufacturing, offering
strength, durability, and environmental advantages. However, the presence of
iron (Fe) impurities poses a major challenge, undermining their properties and
recyclability. Conventional manufacturing processes result in coarse Fe-rich
intermetallic compounds that limit the tolerance of Fe content and negatively
influence performance of advanced aluminum alloys. To address this, rapid
solidification techniques like direct strip casting have been explored. In this
work, a detailed study of the strip cast microstructure was conducted by
scanning electron microscopy, electron backscattered diffraction and atom probe
tomography. Our results reveal that alloys produced by DSC exhibit
significantly refined microstructures and are free from coarse Fe-rich
intermetallics, thereby retaining the majority of Fe in solid solution. These
findings indicate that strip casting significantly enhances Fe-tolerance in
aluminum alloys, making it an attractive process for future aluminum recycling,
with implications for sustainable high-performance applications
Thermal gravity, black holes and cosmological entropy
Taking seriously the interpretation of black hole entropy as the logarithm of
the number of microstates, we argue that thermal gravitons may undergo a phase
transition to a kind of black hole condensate. The phase transition proceeds
via nucleation of black holes at a rate governed by a saddlepoint configuration
whose free energy is of order the inverse temperature in Planck units. Whether
the universe remains in a low entropy state as opposed to the high entropy
black hole condensate depends sensitively on its thermal history. Our results
may clarify an old observation of Penrose regarding the very low entropy state
of the universe.Comment: 5 pages, 2 figures, RevTex. v4: to appear in Phys. Rev.
Past approaches and future directions for targeting tumor hypoxia in squamous cell carcinomas of the head and neck
AbstractRecurrent squamous cell carcinoma of the head and neck (SCCHN) carries a poor prognosis. Tumor hypoxia (TH) has been implicated as one of many factors contributing to SCCHN recurrence. TH leads to radiation resistance by reversing radiation-induced DNA damage. Effective strategies to overcome TH may improve outcomes in patients with SCCHN. We searched the English literature on PubMed and reviewed the reference sections of key articles related to TH (publications spanning from the early 1900s to the present). We summarized the underlying theory of TH in SCCHN, methods for quantifying it, and the numerous therapies developed to modulate it. We included articles that set the foundation of TH as a theory and the most relevant articles published within the last 15 years related to TH quantification and therapeutic targeting. Despite extensive research, targeting TH in SCCHN has not become a part of routine clinical practice in North America, and we analyze the pitfalls in hypoxia research that have led to this failure. We propose that future studies should test a combined approach of targeting the immune system in addition to cellular pathways rendered aberrant in TH and should include development of novel surrogate markers of TH and/or TH imaging
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