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Cells Shows (cell + shows)
Selected AbstractsTel2: a common partner of PIK-related kinases and a link between DNA checkpoint and nutritional response?GENES TO CELLS, Issue 12 2007Junko Kanoh A recent paper (Hayashi et al. 2007) in this issue of Genes to Cells shows that the fission yeast Schizosaccharomyces pombe Tel2, a homologue of mammalian/worm CLK2/Clk-2/Rad-5, physically interacts with all the phosphoinositide 3-kinase-related kinases (PIKKs) that include Rad3/Tel1 (ATR/ATM homologues), Tor1/Tor2 (TOR kinases) and Tra1/Tra2 (TRRAP homologues), raising the possibility that Tel2 family proteins link various PIKK-related cellular processes by interacting with PIKK family proteins. In this minireview, implications and impact of the findings, and a possibility that PIKKs are functionally related through Tel2, are discussed. [source] Synthesis of highly-ordered hierarchical ZnO nanostructures and their application in dye-sensitized solar cellsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2010Y. F. Zhu Abstract In order to improve the performance of ZnO-based solar cells, highly-ordered hierarchical ZnO nanostructures were design and fabricated. The hierarchical nanostructures were grown on FTO (fluorine doped tin oxide, SnO2:F) glass substrates via a facile, low-temperature, and low-cost chemical route. The morphology and structure of the obtained products has been confirmed by field-emission scanning electron microscopy and X-ray diffraction measurements. The performance investigation of the prepared dye-sensitized solar cells (DSSCs) demonstrates that the hierarchical ZnO nanostructure-based solar cell shows a higher short-circuit current density compared with the ZnO nanowire counterpart. The enhanced current density may be due to the fact that the surface area of the hierarchical nanostructures is increased. These results indicate that hierarchical ZnO nanostructures are more suitable for the application as photoelectrode of DSSCs. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Quantitative evaluation of shunts in solar cells by lock-in thermographyPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 8 2003O. Breitenstein Abstract Infrared lock-in thermography allows to image shunts very sensitively in all kinds of solar cells and also to measure dark currents flowing in certain regions of the cell quantitatively. After a summary of the physical basis of lock-in thermography and its practical realization, four types of quantitative measurements are described: local I,V characteristics measured thermally up to a constant factor (LIVT); the quantitative measurement of the current through a local shunt; the evaluation of the influence of shunts on the efficiency of a cell as a function of the illumination intensity; and the mapping of the ideality factor n and the saturation current density J0 over the whole cell. The investigation of a typical multicrystalline solar cell shows that the shunts are predominantly responsible for deterioration of the low-light-level performance of the cell, and that variations of the injection current density related to crystal defects are predominantly determined by variation of J0 rather than of n. Copyright © 2003 John Wiley & Sons, Ltd. [source] Differentiation of the epidermis of scutes in embryos and juveniles of the tortoise Testudo hermanni with emphasis on beta-keratinizationACTA ZOOLOGICA, Issue 3 2005L. Alibardi Abstract The sequence of differentiation of the epidermis of scutes during embryogenesis in the tortoise Testudo hermanni was studied using autoradiography, electron microscopy and immunocytochemistry. The study was mainly conducted on the epidermis of the carapace, plastron and nail. Epidermal differentiation resembles that described for other reptiles, and the embryonic epidermis is composed of numerous cell layers. In the early stages of differentiation of the carapacial ridge, cytoplasmic blebs of epidermal cells are in direct contact with the extracellular matrix and mesenchymal cells. The influence of the dermis on the formation of the beta-layer is discussed. The dermis becomes rich in collagen bundles at later stages of development. The embryonic epidermis is formed by a flat periderm and four to six layers of subperidermal cells, storing 40,70-nm-thick coarse filaments that may represent interkeratin or matrix material. Beta-keratin is associated with the coarse filaments, suggesting that the protein may be polymerized on their surface. The presence of beta-keratin in embryonic epidermis suggests that this keratin might have been produced at the beginning of chelonian evolution. The embryonic epidermis of the scutes is lost around hatching and leaves underneath the definitive corneous beta-layer. Beneath the embryonic epidermis, cells that accumulate typical large bundles of beta-keratin appear at stage 23 and at hatching a compact beta-layer is present. The differentiation of these cells shows the progressive replacement of alpha-keratin bundles with bundles immunolabelled for beta-keratin. The nucleus is degraded and electron-dense nuclear material mixes with beta-keratin. In general, changes in tortoise skin when approaching terrestrial life resemble those of other reptiles. Lepidosaurian reptiles form an embryonic shedding layer and crocodilians have a thin embryonic epidermis that is rapidly lost near hacthing. Chelonians have a thicker embryonic epidermis that accumulates beta-keratin, a protein later used to make a thick corneous layer. [source] In vivo post-transcriptional regulation of CD154 in mouse CD4+ T cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2009Stefano Vavassori Abstract Interactions between CD40 and its ligand CD154 are involved in the progression of both cell mediated and innate immunity. These interactions are brought about by the transient expression of CD154 on activated CD4+ T cells, which is regulated, in part, at the level of mRNA turnover. Here we have focused on analyzing the pattern of post-transcriptional regulation in mouse CD4+ T cells in response to activation. Initial experiments identify a region of the murine CD154 mRNA that binds a polypyrimidine tract-binding protein-containing complex (mComplex I), which is activation-dependent and binds to a single CU-rich site within the 3, uTR Subsequent findings demonstrate that in vivo polyclonal activation of T cells leads to a pattern of differential CD154 mRNA stability that is directly dependent on extent of activation. Furthermore, in vitro activation of antigen-primed T cells shows that the CD154 mRNA half-life increases relative to that of unprimed cells. Importantly, this is the first report demonstrating that the regulation of CD154 in vivo is connected to an activation-induced program of mRNA decay and thus provides strong evidence for post-transcriptional mechanisms having a physiological role in regulating CD154 expression during an ongoing immune response. [source] A highly linear and efficient three-way Doherty amplifier using two-stage GaN HEMT cells for repeater systemsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2009Yong-Sub Lee Abstract In this article, we propose a highly linear and efficient three-way Doherty amplifier using two-stage GaN HEMT cells for repeater systems. The driving cells are used as the predistortion circuit to improve linearity as well as the gain stage. The main cells are optimized to achieve high efficiency at a large back-off power. After gate bias optimization of the driving cells, the proposed three-way Doherty amplifier with two-stage cells shows highly linear and efficient performance. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2895,2898, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24748 [source] Diversity in conducting cells in early land plants and comparisons with extant bryophytesBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2003D. EDWARDS Anatomical screening using scanning electron microscopy (SEM) of short lengths of smooth coalified axes (mesofossils) from a Lochkovian (Lower Devonian) locality in the Welsh Borderland, Shropshire has revealed extensive diversity in the architecture of centrally aggregated, elongate cells. At least 14 types have been discovered, each distinguished by variation in wall architecture and combination of the cells in the central strand. End walls have not been seen. These elongate cells may have smooth, uniformly thick or thin walls, walls with smooth projections either traversing or lining the lumen, or bilayered walls, the innermost perforated by pores of plasmodesmata dimensions. The latter type may be further divided on presence or absence of projections which may line the lumen, but usually cross it and are highly disorganized. Indeed, none of the cells shows the regularity associated with the secondary thickenings of tracheids, but the imperforate/pitted forms with projections superficially resemble the S-type tracheids of the Rhyniopsida in basic construction. Simply pitted types show greater similarity with the water-conducting cells (WCCs) of liverworts and Takakia. To facilitate direct comparison with bryophyte conducting elements, SEM studies were undertaken on the WCCs of a number of mosses and liverworts and on the leptoids of mosses, in conjunction with a range of degradation experiments designed to assess the fossilization potential of these cells. With the exception of polytrichaceous hydroids, the latter demonstrated the resilience of hydroids and leptoids to the chemical treatments. In addition, dehydration of the leptoids produced globular residues similar to those seen in some of the fossils. This combination of techniques raises the possibility that food-conducting cells might well be preserved in coalified fossils, and hence extends the interpretation of the functions of the elongate cells. Broadly speaking, imperforate bilayered examples may have been involved in water conduction, cells with globular residues with or without pitting involved in metabolite movement, and smooth walled examples with or without projections involved in support. The wider affinities of the plants which produced the axes remain equivocal and in the absence of sporangia it is impossible to assign them to a genus. However, this anatomical diversity in vegetative remains of extreme simplicity demonstrates far greater diversity in early land vegetation than is apparent from perusal of species lists. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 141, 297,347. [source] | |||||||||||||