Space solar cells: High efficiency and radiation damage

The progress and status of efforts to increase the end-of-life efficiency of solar cells for space use is assessed. High efficiency silicon solar cells, silicon solar cell radiation damage, GaAs solar cell performance and radiation damage and 30 percent devices are discussed

On the cause of the flat-spot phenomenon observed in silicon solar cells at low temperatures and low intensities

A model is presented that explains the "flat-spot" (FS) power loss phenomenon observed in silicon solar cells operating deep space (low temperature, low intensity) conditions. Evidence is presented suggesting that the effect is due to localized metallurgical interactions between the silicon substrate and the contact metallization. These reactions are shown to result in localized regions in which the PN junction is destroyed and replaced with a metal-semiconductor-like interface. The effects of thermal treatment, crystallographic orientation, junction depth, and metallurization are presented along with a method of preventing the effect through the suppression of vacancy formation at the free surface of the contact metallization. Preliminary data indicating the effectiveness of a TiN diffusion barrier in preventing the effect are also given

The Case for Perspicuous Programming

This essay examines the nature of programs, classifies the traditional or enigmatic styles of programming, distinguishing template, prose and literate styles; notes the contrast between batch programs and interactive programs; and highlights the advantages of giving priority in developing interactive programs to the online documentation, and proposes that this documentation should be the principal target of development, with the executable program code being regarded of secondary and consequent

Liver-directed chemotherapy of cetuximab and bevacizumab in combination with oxaliplatin is more effective to inhibit tumor growth of CC531 colorectal rat liver metastases than systemic chemotherapy

Colorectal carcinoma is, through to its high rate of liver metastasis (mCRC), the second most cause of cancer death worldwide. Tumor resection represents the only potential cure. In cases of unresectable disease systemic chemotherapy (sCHT) remains the therapy of choice. Modern sCHT regimens including biological agents can induce tumor response that leads to curative surgery of initially unresectable mCRC. However, liver-directed therapy via hepatic arterial infusion (HAI) may produce higher response rates than sCHT. Herein we studied whether a HAI of cetuximab (CE) plus bevacizumab (BE) with or without oxaliplatin (OX) can inhibit tumor growth in a rat model. WAG/Rij rats underwent subcapsular hepatic tumor implantation. After 10 days animals received either HAI or sCHT of CE plus BE, OX or all three drugs. Saline-treated animals served as controls. Tumor growth was estimated at day 10 and 13. On day 13 liver and tumor tissue was studied histologically and immunohistochemically. In controls the tumors grew about 50 %. OX alone was not capable of inhibiting tumor growth. In contrast, CE plus BE given as HAI significantly reduced tumor growth compared to sCHT (p < 0.05). HAI of CE plus BE combined with OX yielded an even more pronounced inhibition of tumor growth. Immunohistochemistry revealed a decreased tumor cell proliferation and tumor vascularization. The present study demonstrates that HAI of CE plus BE is effective to inhibit tumor growth. This effect is even more pronounced in combination with OX. Systemic application of these agents cannot achieve comparable effects

Sublittoral soft bottom communities and diversity of Mejillones Bay in northern Chile (Humboldt Current upwelling system)

The macrozoobenthos of Mejillones Bay (23°S; Humboldt Current) was quantitatively investigated over a 7-year period from austral summer 1995/1996 to winter 2002. About 78 van Veen grab samples taken at six stations (5, 10, 20 m depth) provided the basis for the analysis of the distribution of 60 species and 28 families of benthic invertebrates, as well as of their abundance and biomass. Mean abundance (2,119 individuals m-2) was in the same order compared to a previous investigation; mean biomass (966 g formalin wet mass m-2), however, exceeded prior estimations mainly due to the dominance of the bivalve Aulacomya ater. About 43% of the taxa inhabited the complete depth range. Mean taxonomic Shannon diversity (H', Log e) was 1.54 ± 0.58 with a maximum at 20 m (1.95 ± 0.33); evenness increased with depth. The fauna was numerically dominated by carnivorous gastropods, polychaetes and crustaceans (48%). About 15% of the species were suspensivorous, 13% sedimentivorous, 11% detritivorous, 7% omnivorous and 6% herbivorous. Cluster analyses showed a significant difference between the shallow and the deeper stations. Gammarid amphipods and the polychaete family Nephtyidae characterized the 5-mzone, the molluscs Aulacomya ater, Mitrella unifasciata and gammarids the intermediate zone, while the gastropod Nassarius gayi and the polychaete family Nereidae were most prominent at the deeper stations. The communities of the three depth zones did not appear to be limited by hypoxia during non-El Niño conditions. Therefore, no typical change in community structure occurred during El Niño 1997–1998, in contrast to what was observed for deeper faunal assemblages and hypoxic bays elsewhere in the coastal Humboldt Current system

Perfluorodecalin enhances in vivo confocal microscopy resolution of Arabidopsis thaliana mesophyll.

*Air spaces in the leaf mesophyll generate deleterious optical effects that compromise confocal microscopy. *Leaves were mounted in the nontoxic, nonfluorescent perfluorocarbon, perfluorodecalin (PFD), and optical enhancement and physiological effect were assessed using confocal microscopy and chlorophyll fluorescence. *Mounting leaves of Arabidopsis thaliana in PFD significantly improved the optical qualities of the leaf, thereby enabling high-resolution laser scanning confocal imaging over twofold deeper into the mesophyll, compared with using water. Incubation in PFD had less physiological impact on the mounted specimen than water. *We conclude that the application of PFD as a mounting medium substantially increases confocal image resolution of living mesophyll and vascular bundle cells, with minimal physiological impact

Innate Recognition of Fungal Cell Walls

The emergence of fungal infections as major causes of morbidity and mortality in immunosuppressed individuals has prompted studies into how the host recognizes fungal pathogens. Fungi are eukaryotes and as such share many similarities with mammalian cells. The most striking difference, though, is the presence of a cell wall that serves to protect the fungus from environmental stresses, particularly osmotic changes [1]. This task is made challenging because the fungus must remodel itself to allow for cell growth and division, including the conversion to different morphotypes, such as occurs during germination of spherical spores into filamentous hyphae. The cell wall also connects the fungus with its environment by triggering intracellular signaling pathways and mediating adhesion to other cells and extracellular matrices. Here, important facts and concepts critical for understanding innate sensing of the fungal cell wall by mammalian pathogens are reviewed

A Practical Guide to Rodent Islet Isolation and Assessment

Pancreatic islets of Langerhans secrete hormones that are vital to the regulation of blood glucose and are, therefore, a key focus of diabetes research. Purifying viable and functional islets from the pancreas for study is an intricate process. This review highlights the key elements involved with mouse and rat islet isolation, including choices of collagenase, the collagenase digestion process, purification of islets using a density gradient, and islet culture conditions. In addition, this paper reviews commonly used techniques for assessing islet viability and function, including visual assessment, fluorescent markers of cell death, glucose-stimulated insulin secretion, and intracellular calcium measurements. A detailed protocol is also included that describes a common method for rodent islet isolation that our laboratory uses to obtain viable and functional mouse islets for in vitro study of islet function, beta-cell physiology, and in vivo rodent islet transplantation. The purpose of this review is to serve as a resource and foundation for successfully procuring and purifying high-quality islets for research purposes

The TIP30 Protein Complex, Arachidonic Acid and Coenzyme A Are Required for Vesicle Membrane Fusion

Efficient membrane fusion has been successfully mimicked in vitro using artificial membranes and a number of cellular proteins that are currently known to participate in membrane fusion. However, these proteins are not sufficient to promote efficient fusion between biological membranes, indicating that critical fusogenic factors remain unidentified. We have recently identified a TIP30 protein complex containing TIP30, acyl-CoA synthetase long-chain family member 4 (ACSL4) and Endophilin B1 (Endo B1) that promotes the fusion of endocytic vesicles with Rab5a vesicles, which transport endosomal acidification enzymes vacuolar (H+)-ATPases (V-ATPases) to the early endosomes in vivo. Here, we demonstrate that the TIP30 protein complex facilitates the fusion of endocytic vesicles with Rab5a vesicles in vitro. Fusion of the two vesicles also depends on arachidonic acid, coenzyme A and the synthesis of arachidonyl-CoA by ACSL4. Moreover, the TIP30 complex is able to transfer arachidonyl groups onto phosphatidic acid (PA), producing a new lipid species that is capable of inducing close contact between membranes. Together, our data suggest that the TIP30 complex facilitates biological membrane fusion through modification of PA on membranes