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Sample records for adherens junctions caused

  1. Genetic deletion of afadin causes hydrocephalus by destruction of adherens junctions in radial glial and ependymal cells in the midbrain.

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    Hideaki Yamamoto

    Full Text Available Adherens junctions (AJs play a role in mechanically connecting adjacent cells to maintain tissue structure, particularly in epithelial cells. The major cell-cell adhesion molecules at AJs are cadherins and nectins. Afadin binds to both nectins and α-catenin and recruits the cadherin-β-catenin complex to the nectin-based cell-cell adhesion site to form AJs. To explore the role of afadin in radial glial and ependymal cells in the brain, we generated mice carrying a nestin-Cre-mediated conditional knockout (cKO of the afadin gene. Newborn afadin-cKO mice developed hydrocephalus and died neonatally. The afadin-cKO brain displayed enlarged lateral ventricles and cerebral aqueduct, resulting from stenosis of the caudal end of the cerebral aqueduct and obliteration of the ventral part of the third ventricle. Afadin deficiency further caused the loss of ependymal cells from the ventricular and aqueductal surfaces. During development, radial glial cells, which terminally differentiate into ependymal cells, scattered from the ventricular zone and were replaced by neurons that eventually covered the ventricular and aqueductal surfaces of the afadin-cKO midbrain. Moreover, the denuded ependymal cells were only occasionally observed in the third ventricle and the cerebral aqueduct of the afadin-cKO midbrain. Afadin was co-localized with nectin-1 and N-cadherin at AJs of radial glial and ependymal cells in the control midbrain, but these proteins were not concentrated at AJs in the afadin-cKO midbrain. Thus, the defects in the afadin-cKO midbrain most likely resulted from the destruction of AJs, because AJs in the midbrain were already established before afadin was genetically deleted. These results indicate that afadin is essential for the maintenance of AJs in radial glial and ependymal cells in the midbrain and is required for normal morphogenesis of the cerebral aqueduct and ventral third ventricle in the midbrain.

  2. Fibroblast growth factor signaling potentiates VE-cadherin stability at adherens junctions by regulating SHP2.

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    Kunihiko Hatanaka

    Full Text Available BACKGROUND: The fibroblast growth factor (FGF system plays a critical role in the maintenance of vascular integrity via enhancing the stability of VE-cadherin at adherens junctions. However, the precise molecular mechanism is not well understood. In the present study, we aimed to investigate the detailed mechanism of FGF regulation of VE-cadherin function that leads to endothelial junction stabilization. METHODS AND FINDINGS: In vitro studies demonstrated that the loss of FGF signaling disrupts the VE-cadherin-catenin complex at adherens junctions by increasing tyrosine phosphorylation levels of VE-cadherin. Among protein tyrosine phosphatases (PTPs known to be involved in the maintenance of the VE-cadherin complex, suppression of FGF signaling reduces SHP2 expression levels and SHP2/VE-cadherin interaction due to accelerated SHP2 protein degradation. Increased endothelial permeability caused by FGF signaling inhibition was rescued by SHP2 overexpression, indicating the critical role of SHP2 in the maintenance of endothelial junction integrity. CONCLUSIONS: These results identify FGF-dependent maintenance of SHP2 as an important new mechanism controlling the extent of VE-cadherin tyrosine phosphorylation, thereby regulating its presence in adherens junctions and endothelial permeability.

  3. The adherens junctions control susceptibility to Staphylococcus aureus α-toxin.

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    Popov, Lauren M; Marceau, Caleb D; Starkl, Philipp M; Lumb, Jennifer H; Shah, Jimit; Guerrera, Diego; Cooper, Rachel L; Merakou, Christina; Bouley, Donna M; Meng, Wenxiang; Kiyonari, Hiroshi; Takeichi, Masatoshi; Galli, Stephen J; Bagnoli, Fabio; Citi, Sandra; Carette, Jan E; Amieva, Manuel R

    2015-11-17

    Staphylococcus aureus is both a transient skin colonizer and a formidable human pathogen, ranking among the leading causes of skin and soft tissue infections as well as severe pneumonia. The secreted bacterial α-toxin is essential for S. aureus virulence in these epithelial diseases. To discover host cellular factors required for α-toxin cytotoxicity, we conducted a genetic screen using mutagenized haploid human cells. Our screen identified a cytoplasmic member of the adherens junctions, plekstrin-homology domain containing protein 7 (PLEKHA7), as the second most significantly enriched gene after the known α-toxin receptor, a disintegrin and metalloprotease 10 (ADAM10). Here we report a new, unexpected role for PLEKHA7 and several components of cellular adherens junctions in controlling susceptibility to S. aureus α-toxin. We find that despite being injured by α-toxin pore formation, PLEKHA7 knockout cells recover after intoxication. By infecting PLEKHA7(-/-) mice with methicillin-resistant S. aureus USA300 LAC strain, we demonstrate that this junctional protein controls disease severity in both skin infection and lethal S. aureus pneumonia. Our results suggest that adherens junctions actively control cellular responses to a potent pore-forming bacterial toxin and identify PLEKHA7 as a potential nonessential host target to reduce S. aureus virulence during epithelial infections.

  4. The Drosophila genes crumbs and stardust are involved in the biogenesis of adherens junctions.

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    Grawe, F; Wodarz, A; Lee, B; Knust, E; Skaer, H

    1996-03-01

    Morphogenetic movements of epithelia during development underlie the normal elaboration of the final body plan. The tissue integrity critical for these movements is conferred by anchorage of the cytoskeleton by adherens junctions, initially spot and later belt-like, zonular structures, which encircle the apical side of the cell. Loss-of-function mutations in the Drosophila genes crumbs and stardust lead to the loss of cell polarity in most ectodermally derived epithelia, followed in some, such as the epidermis, by extensive apoptosis. Here we show that both mutants fail to establish proper zonulae adherentes in the epidermis. Our results suggest that the two genes are involved in different aspects of this process. Further, they are compatible with the hypothesis that crumbs delimits the apical border, where the zonula adherens usually forms and where Crumbs protein is normally most abundant. In contrast, stardust seems to be required at an earlier stage for the assembly of the spot adherence junctions. In both mutants, the defect observed at the ultrastructural level are preceded by a misdistribution of Armadillo and DE-cadherin, the homologues of beta-catenin and E-cadherin, respectively, which are two constituents of the vertebrate adherens junctions. Strikingly, expansion of the apical membrane domain in epidermal cells by overexpression of crumbs also abolishes the formation of adherens junctions and results in the disruption of tissue integrity, but without loss of membrane polarity. This result supports the view that membrane polarity is independent of the formation of adherens junctions in epidermal cells.

  5. Rab11 helps maintain apical crumbs and adherens junctions in the Drosophila embryonic ectoderm.

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    Jeremiah F Roeth

    Full Text Available BACKGROUND: Tissue morphogenesis and organogenesis require that cells retain stable cell-cell adhesion while changing shape and moving. One mechanism to accommodate this plasticity in cell adhesion involves regulated trafficking of junctional proteins. METHODOLOGY/PRINCIPAL FINDINGS: Here we explored trafficking of junctional proteins in two well-characterized model epithelia, the Drosophila embryonic ectoderm and amnioserosa. We find that DE-cadherin, the transmembrane protein of adherens junctions, is actively trafficked through putative vesicles, and appears to travel through both Rab5-positive and Rab11-positive structures. We manipulated the functions of Rab11 and Rab5 to examine the effects on junctional stability and morphogenesis. Reducing Rab11 function, either using a dominant negative construct or loss of function alleles, disrupts integrity of the ectoderm and leads to loss of adherens junctions. Strikingly, the apical junctional regulator Crumbs is lost before AJs are destabilized, while the basolateral protein Dlg remains cortical. Altering Rab5 function had less dramatic effects, not disrupting adherens junction integrity but affecting dorsal closure. CONCLUSIONS/SIGNIFICANCE: We contrast our results with what others saw when disrupting other trafficking regulators, and when disrupting Rab function in other tissues; together these data suggest distinct mechanisms regulate junctional stability and plasticity in different tissues.

  6. DHT deficiency perturbs the integrity of the rat seminiferous epithelium by disrupting tight and adherens junctions.

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    Kolasa, Agnieszka; Marchlewicz, Mariola; Wenda-Różewicka, Lidia; Wiszniewska, Barbara

    2011-01-01

    In rats with a DHT deficiency induced by finasteride, morphological changes in the seminiferous epithelium were observed. The structural alterations were manifested by the premature germ cells sloughing into the lumen of seminiferous tubules. The etiology of this disorder could be connected with intercellular junctions disintegration. We showed in the immunohistochemical study the changes in expression of some proteins building tight and adherens junctions. The depression of N-cadherin, β-catenin and occludin immunoexpressions could be the reason for the release of immature germ cells from the seminiferous epithelium. However, the observed increase of the immunohistochemical reaction intensity of vinculin, one of the cadherin/catenin complex regulators, could be insufficient to maintain the proper function of adherens junctions. The hormonal imbalance appears to influence the pattern of expression of junctional proteins in the seminiferous epithelium. It could lead to untimely germ cells sloughing, and ultimately could impair fertility.

  7. Differential regulation of the Hippo pathway by adherens junctions and apical-basal cell polarity modules.

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    Yang, Chih-Chao; Graves, Hillary K; Moya, Ivan M; Tao, Chunyao; Hamaratoglu, Fisun; Gladden, Andrew B; Halder, Georg

    2015-02-10

    Adherens junctions (AJs) and cell polarity complexes are key players in the establishment and maintenance of apical-basal cell polarity. Loss of AJs or basolateral polarity components promotes tumor formation and metastasis. Recent studies in vertebrate models show that loss of AJs or loss of the basolateral component Scribble (Scrib) cause deregulation of the Hippo tumor suppressor pathway and hyperactivation of its downstream effectors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). However, whether AJs and Scrib act through the same or independent mechanisms to regulate Hippo pathway activity is not known. Here, we dissect how disruption of AJs or loss of basolateral components affect the activity of the Drosophila YAP homolog Yorkie (Yki) during imaginal disc development. Surprisingly, disruption of AJs and loss of basolateral proteins produced very different effects on Yki activity. Yki activity was cell-autonomously decreased but non-cell-autonomously elevated in tissues where the AJ components E-cadherin (E-cad) or α-catenin (α-cat) were knocked down. In contrast, scrib knockdown caused a predominantly cell-autonomous activation of Yki. Moreover, disruption of AJs or basolateral proteins had different effects on cell polarity and tissue size. Simultaneous knockdown of α-cat and scrib induced both cell-autonomous and non-cell-autonomous Yki activity. In mammalian cells, knockdown of E-cad or α-cat caused nuclear accumulation and activation of YAP without overt effects on Scrib localization and vice versa. Therefore, our results indicate the existence of multiple, genetically separable inputs from AJs and cell polarity complexes into Yki/YAP regulation.

  8. Alteration of Tight and Adherens Junctions on 50-Hz Magnetic Field Exposure in Madin Darby Canine Kidney (MDCK Cells

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    Zoltán Somosy

    2004-01-01

    Full Text Available Adherens (AJ and tight junctions (TJ, as integrated parts of the junctional complex, are multifunctional specialized regions of the cell membrane in epithelial cells. They are responsible for cell-to-cell interactions and also have great importance in cellular signaling processes including Wnt protein-mediated signals. As electromagnetic field (EMF exposure is known to cause alterations in the function as well as supramolecular organization of different cell contacts, our goal was to investigate the effect of 50-Hz magnetic field (MF exposures on the subcellular distribution of some representative structural proteins (occludin, β-catenin, and cadherin found in AJ and TJ. Additionally, cellular β-catenin content was also quantified by Western blot analysis. 50-Hz MF exposures seemed to increase the staining intensity (amount of occludin, cadherins, and β-catenin in the junctional area of MDCK cells, while Western blot data indicated the quantity of b-catenin was found significantly decreased at both time points after EM exposures. Our results demonstrate that MF are able to modify the distribution of TJ and AJ structural proteins, tending to stabilize these cell contacts. The quantitative changes of β-catenin suggest a causative relationship between MF effects on the cell junctional complex and the Wnt signaling pathway.

  9. Carcinoembryonic antigen promotes colorectal cancer progression by targeting adherens junction complexes

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    Bajenova, Olga, E-mail: o.bazhenova@spbu.ru [Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); Chaika, Nina [Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); Tolkunova, Elena; Davydov-Sinitsyn, Alexander [Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064 (Russian Federation); Gapon, Svetlana [Boston Children' s Hospital, Boston, MA 02115 (United States); Thomas, Peter [Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); O’Brien, Stephen [Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg 199034 (Russian Federation)

    2014-06-10

    Oncomarkers play important roles in the detection and management of human malignancies. Carcinoembryonic antigen (CEA, CEACAM5) and epithelial cadherin (E-cadherin) are considered as independent tumor markers in monitoring metastatic colorectal cancer. They are both expressed by cancer cells and can be detected in the blood serum. We investigated the effect of CEA production by MIP101 colorectal carcinoma cell lines on E-cadherin adherens junction (AJ) protein complexes. No direct interaction between E-cadherin and CEA was detected; however, the functional relationships between E-cadherin and its AJ partners: α-, β- and p120 catenins were impaired. We discovered a novel interaction between CEA and beta-catenin protein in the CEA producing cells. It is shown in the current study that CEA overexpression alters the splicing of p120 catenin and triggers the release of soluble E-cadherin. The influence of CEA production by colorectal cancer cells on the function of E-cadherin junction complexes may explain the link between the elevated levels of CEA and the increase in soluble E-cadherin during the progression of colorectal cancer. - Highlights: • Elevated level of CEA increases the release of soluble E-cadherin during the progression of colorectal cancer. • CEA over-expression alters the binding preferences between E-cadherin and its partners: α-, β- and p120 catenins in adherens junction complexes. • CEA produced by colorectal cancer cells interacts with beta-catenin protein. • CEA over-expression triggers the increase in nuclear beta-catenin. • CEA over-expression alters the splicing of p120 catenin protein.

  10. An introduction to adherens junctions: from molecular mechanisms to tissue development and disease.

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    Harris, Tony J C

    2012-01-01

    Adherens junctions (AJs) are fundamental for the development of animal tissues and organs. The core complex is formed from transmembrane cell-cell adhesion molecules, cadherins, and adaptor molecules, the catenins, that link to cytoskeletal and regulatory networks within the cell. This complex can be considered over a wide range of biological organization, from atoms to molecules, protein complexes, molecular networks, cells, tissues, and overall animal development. AJs have also been an integral part of animal evolution, and play central roles in cancer development and pathogen infection. This book addresses major questions encompassing these aspects of AJ biology. How did AJs evolve? How do the cadherins and catenins interact to assemble AJs and mediate adhesion? How do AJs interface with other cellular machinery to couple adhesion with the whole cell? How do AJs affect cell behaviour and multicellular development? How can abnormal AJ activity lead to disease?

  11. Endothelial Cell Permeability and Adherens Junction Disruption Induced by Junín Virus Infection

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    Lander, Heather M.; Grant, Ashley M.; Albrecht, Thomas; Hill, Terence; Peters, Clarence J.

    2014-01-01

    Junín virus (JUNV) is endemic to the fertile Pampas of Argentina, maintained in nature by the rodent host Calomys musculinus, and the causative agent of Argentine hemorrhagic fever (AHF), which is characterized by vascular dysfunction and fluid distribution abnormalities. Clinical as well as experimental studies implicate involvement of the endothelium in the pathogenesis of AHF, although little is known of its role. JUNV has been shown to result in productive infection of endothelial cells (ECs) in vitro with no visible cytopathic effects. In this study, we show that direct JUNV infection of primary human ECs results in increased vascular permeability as measured by electric cell substrate impedance sensing and transwell permeability assays. We also show that EC adherens junctions are disrupted during virus infection, which may provide insight into the role of the endothelium in the pathogenesis of AHF and possibly, other viral hemorrhagic fevers. PMID:24710609

  12. Photoperiod-Dependent Effects of 4-tert-Octylphenol on Adherens and Gap Junction Proteins in Bank Vole Seminiferous Tubules

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    Anna Hejmej

    2013-01-01

    Full Text Available In the present study we evaluated in vivo and in vitro effects of 4-tert-octylphenol (OP on the expression and distribution of adherens and gap junction proteins, N-cadherin, β-catenin, and connexin 43 (Cx43, in testes of seasonally breeding rodents, bank voles. We found that in bank vole testes expression and distribution of N-cadherin, β-catenin, and Cx43 were photoperiod dependent. Long-term treatment with OP (200 mg/kg b.w. resulted in the reduction of junction proteins expressions (P<0.05, P<0.01 and their delocalization in the testes of males kept in long photoperiod, whereas in short-day animals slight increase of Cx43 (P<0.05, N-cadherin, and β-catenin (statistically nonsignificant levels was observed. Effects of OP appeared to be independent of FSH and were maintained during in vitro organ culture, indicating that OP acts directly on adherens and gap junction proteins in the testes. An experiment performed using an antiestrogen ICI 182,780 demonstrated that the biological effects of OP on β-catenin and Cx43 involve an estrogen receptor-mediated response. Taken together, in bank vole organization of adherens and gap junctions and their susceptibility to OP are related to the length of photoperiod. Alterations in cadherin/catenin and Cx43-based junction may partially result from activation of estrogen receptor α and/or β signaling pathway.

  13. HIV-associated disruption of tight and adherens junctions of oral epithelial cells facilitates HSV-1 infection and spread.

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    Sufiawati, Irna; Tugizov, Sharof M

    2014-01-01

    Herpes simplex virus (HSV) types 1 and 2 are the most common opportunistic infections in HIV/AIDS. In these immunocompromised individuals, HSV-1 reactivates and replicates in oral epithelium, leading to oral disorders such as ulcers, gingivitis, and necrotic lesions. Although the increased risk of HSV infection may be mediated in part by HIV-induced immune dysfunction, direct or indirect interactions of HIV and HSV at the molecular level may also play a role. In this report we show that prolonged interaction of the HIV proteins tat and gp120 and cell-free HIV virions with polarized oral epithelial cells leads to disruption of tight and adherens junctions of epithelial cells through the mitogen-activated protein kinase signaling pathway. HIV-induced disruption of oral epithelial junctions facilitates HSV-1 paracellular spread between the epithelial cells. Furthermore, HIV-associated disruption of adherens junctions exposes sequestered nectin-1, an adhesion protein and critical receptor for HSV envelope glycoprotein D (gD). Exposure of nectin-1 facilitates binding of HSV-1 gD, which substantially increases HSV-1 infection of epithelial cells with disrupted junctions over that of cells with intact junctions. Exposed nectin-1 from disrupted adherens junctions also increases the cell-to-cell spread of HSV-1 from infected to uninfected oral epithelial cells. Antibodies to nectin-1 and HSV-1 gD substantially reduce HSV-1 infection and cell-to-cell spread, indicating that HIV-promoted HSV infection and spread are mediated by the interaction of HSV gD with HIV-exposed nectin-1. Our data suggest that HIV-associated disruption of oral epithelial junctions may potentiate HSV-1 infection and its paracellular and cell-to-cell spread within the oral mucosal epithelium. This could be one of the possible mechanisms of rapid development of HSV-associated oral lesions in HIV-infected individuals.

  14. HIV-associated disruption of tight and adherens junctions of oral epithelial cells facilitates HSV-1 infection and spread.

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    Irna Sufiawati

    Full Text Available Herpes simplex virus (HSV types 1 and 2 are the most common opportunistic infections in HIV/AIDS. In these immunocompromised individuals, HSV-1 reactivates and replicates in oral epithelium, leading to oral disorders such as ulcers, gingivitis, and necrotic lesions. Although the increased risk of HSV infection may be mediated in part by HIV-induced immune dysfunction, direct or indirect interactions of HIV and HSV at the molecular level may also play a role. In this report we show that prolonged interaction of the HIV proteins tat and gp120 and cell-free HIV virions with polarized oral epithelial cells leads to disruption of tight and adherens junctions of epithelial cells through the mitogen-activated protein kinase signaling pathway. HIV-induced disruption of oral epithelial junctions facilitates HSV-1 paracellular spread between the epithelial cells. Furthermore, HIV-associated disruption of adherens junctions exposes sequestered nectin-1, an adhesion protein and critical receptor for HSV envelope glycoprotein D (gD. Exposure of nectin-1 facilitates binding of HSV-1 gD, which substantially increases HSV-1 infection of epithelial cells with disrupted junctions over that of cells with intact junctions. Exposed nectin-1 from disrupted adherens junctions also increases the cell-to-cell spread of HSV-1 from infected to uninfected oral epithelial cells. Antibodies to nectin-1 and HSV-1 gD substantially reduce HSV-1 infection and cell-to-cell spread, indicating that HIV-promoted HSV infection and spread are mediated by the interaction of HSV gD with HIV-exposed nectin-1. Our data suggest that HIV-associated disruption of oral epithelial junctions may potentiate HSV-1 infection and its paracellular and cell-to-cell spread within the oral mucosal epithelium. This could be one of the possible mechanisms of rapid development of HSV-associated oral lesions in HIV-infected individuals.

  15. Adherens junction distribution mechanisms during cell-cell contact elongation in Drosophila.

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    Gabrielle Goldenberg

    Full Text Available During Drosophila gastrulation, amnioserosa (AS cells flatten and spread as an epithelial sheet. We used AS morphogenesis as a model to investigate how adherens junctions (AJs distribute along elongating cell-cell contacts in vivo. As the contacts elongated, total AJ protein levels increased along their length. However, genetically blocking this AJ addition indicated that it was not essential for maintaining AJ continuity. Implicating other remodeling mechanisms, AJ photobleaching revealed non-directional lateral mobility of AJs along the elongating contacts, as well as local AJ removal from the membranes. Actin stabilization with jasplakinolide reduced AJ redistribution, and live imaging of myosin II along elongating contacts revealed fragmented, expanding and contracting actomyosin networks, suggesting a mechanism for lateral AJ mobility. Actin stabilization also increased total AJ levels, suggesting an inhibition of AJ removal. Implicating AJ removal by endocytosis, clathrin endocytic machinery accumulated at AJs. However, dynamin disruption had no apparent effect on AJs, suggesting the involvement of redundant or dynamin-independent mechanisms. Overall, we propose that new synthesis, lateral diffusion, and endocytosis play overlapping roles to populate elongating cell-cell contacts with evenly distributed AJs in this in vivo system.

  16. Segmentation and tracking of adherens junctions in 3D for the analysis of epithelial tissue morphogenesis.

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    Cilla, Rodrigo; Mechery, Vinodh; Hernandez de Madrid, Beatriz; Del Signore, Steven; Dotu, Ivan; Hatini, Victor

    2015-04-01

    Epithelial morphogenesis generates the shape of tissues, organs and embryos and is fundamental for their proper function. It is a dynamic process that occurs at multiple spatial scales from macromolecular dynamics, to cell deformations, mitosis and apoptosis, to coordinated cell rearrangements that lead to global changes of tissue shape. Using time lapse imaging, it is possible to observe these events at a system level. However, to investigate morphogenetic events it is necessary to develop computational tools to extract quantitative information from the time lapse data. Toward this goal, we developed an image-based computational pipeline to preprocess, segment and track epithelial cells in 4D confocal microscopy data. The computational pipeline we developed, for the first time, detects the adherens junctions of epithelial cells in 3D, without the need to first detect cell nuclei. We accentuate and detect cell outlines in a series of steps, symbolically describe the cells and their connectivity, and employ this information to track the cells. We validated the performance of the pipeline for its ability to detect vertices and cell-cell contacts, track cells, and identify mitosis and apoptosis in surface epithelia of Drosophila imaginal discs. We demonstrate the utility of the pipeline to extract key quantitative features of cell behavior with which to elucidate the dynamics and biomechanical control of epithelial tissue morphogenesis. We have made our methods and data available as an open-source multiplatform software tool called TTT (http://github.com/morganrcu/TTT).

  17. Downregulation of blood-brain barrier phenotype by proinflammatory cytokines involves NADPH oxidase-dependent ROS generation: consequences for interendothelial adherens and tight junctions.

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    Keith D Rochfort

    Full Text Available Blood-brain barrier (BBB dysfunction is an integral feature of neurological disorders and involves the action of multiple proinflammatory cytokines on the microvascular endothelial cells lining cerebral capillaries. There is still however, considerable ambiguity throughout the scientific literature regarding the mechanistic role(s of cytokines in this context, thereby warranting a comprehensive in vitro investigation into how different cytokines may cause dysregulation of adherens and tight junctions leading to BBB permeabilization.The present study employs human brain microvascular endothelial cells (HBMvECs to compare/contrast the effects of TNF-α and IL-6 on BBB characteristics ranging from the expression of interendothelial junction proteins (VE-cadherin, occludin and claudin-5 to endothelial monolayer permeability. The contribution of cytokine-induced NADPH oxidase activation to altered barrier phenotype was also investigated.In response to treatment with either TNF-α or IL-6 (0-100 ng/ml, 0-24 hrs, our studies consistently demonstrated significant dose- and time-dependent decreases in the expression of all interendothelial junction proteins examined, in parallel with dose- and time-dependent increases in ROS generation and HBMvEC permeability. Increased expression and co-association of gp91 and p47, pivotal NADPH oxidase subunits, was also observed in response to either cytokine. Finally, cytokine-dependent effects on junctional protein expression, ROS generation and endothelial permeability could all be attenuated to a comparable extent using a range of antioxidant strategies, which included ROS depleting agents (superoxide dismutase, catalase, N-acetylcysteine, apocynin and targeted NADPH oxidase blockade (gp91 and p47 siRNA, NSC23766.A timely and wide-ranging investigation comparing the permeabilizing actions of TNF-α and IL-6 in HBMvECs is presented, in which we demonstrate how either cytokine can similarly downregulate the

  18. Drosophila PATJ supports adherens junction stability by modulating Myosin light chain activity

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    Sen, Arnab; Nagy-Zsvér-Vadas, Zsanett; Krahn, Michael P

    2012-01-01

    ... (Pals1-associated tight junction protein) was not per se crucial for the maintenance of apical-basal polarity in Drosophila melanogaster epithelial cells but rather regulated Myosin localization and phosphorylation...

  19. PLEKHA7 is an adherens junction protein with a tissue distribution and subcellular localization distinct from ZO-1 and E-cadherin.

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    Pamela Pulimeno

    Full Text Available The pleckstrin-homology-domain-containing protein PLEKHA7 was recently identified as a protein linking the E-cadherin-p120 ctn complex to the microtubule cytoskeleton. Here we characterize the expression, tissue distribution and subcellular localization of PLEKHA7 by immunoblotting, immunofluorescence microscopy, immunoelectron microscopy, and northern blotting in mammalian tissues. Anti-PLEKHA7 antibodies label the junctional regions of cultured kidney epithelial cells by immunofluorescence microscopy, and major polypeptides of M(r approximately 135 kDa and approximately 145 kDa by immunoblotting of lysates of cells and tissues. Two PLEKHA7 transcripts ( approximately 5.5 kb and approximately 6.5 kb are detected in epithelial tissues. PLEKHA7 is detected at epithelial junctions in sections of kidney, liver, pancreas, intestine, retina, and cornea, and its tissue distribution and subcellular localization are distinct from ZO-1. For example, PLEKHA7 is not detected within kidney glomeruli. Similarly to E-cadherin, p120 ctn, beta-catenin and alpha-catenin, PLEKHA7 is concentrated in the apical junctional belt, but unlike these adherens junction markers, and similarly to afadin, PLEKHA7 is not localized along the lateral region of polarized epithelial cells. Immunoelectron microscopy definitively establishes that PLEKHA7 is localized at the adherens junctions in colonic epithelial cells, at a mean distance of 28 nm from the plasma membrane. In summary, we show that PLEKHA7 is a cytoplasmic component of the epithelial adherens junction belt, with a subcellular localization and tissue distribution that is distinct from that of ZO-1 and most AJ proteins, and we provide the first description of its distribution and localization in several tissues.

  20. Alpha-catenin-Dependent Recruitment of the Centrosomal Protein CAP350 to Adherens Junctions Allows Epithelial Cells to Acquire a Columnar Shape

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    Zurbano, Angel; Formstecher, Etienne; Martinez-Morales, Juan R.; Bornens, Michel; Rios, Rosa M.

    2015-01-01

    Epithelial morphogenesis involves a dramatic reorganisation of the microtubule cytoskeleton. How this complex process is controlled at the molecular level is still largely unknown. Here, we report that the centrosomal microtubule (MT)-binding protein CAP350 localises at adherens junctions in epithelial cells. By two-hybrid screening, we identified a direct interaction of CAP350 with the adhesion protein α-catenin that was further confirmed by co-immunoprecipitation experiments. Block of epithelial cadherin (E-cadherin)-mediated cell-cell adhesion or α-catenin depletion prevented CAP350 localisation at cell-cell junctions. Knocking down junction-located CAP350 inhibited the establishment of an apico-basal array of microtubules and impaired the acquisition of columnar shape in Madin-Darby canine kidney II (MDCKII) cells grown as polarised epithelia. Furthermore, MDCKII cystogenesis was also defective in junctional CAP350-depleted cells. CAP350-depleted MDCKII cysts were smaller and contained either multiple lumens or no lumen. Membrane polarity was not affected, but cortical microtubule bundles did not properly form. Our results indicate that CAP350 may act as an adaptor between adherens junctions and microtubules, thus regulating epithelial differentiation and contributing to the definition of cell architecture. We also uncover a central role of α-catenin in global cytoskeleton remodelling, in which it acts not only on actin but also on MT reorganisation during epithelial morphogenesis. PMID:25764135

  1. Mild hypothermia alleviates brain oedema and blood-brain barrier disruption by attenuating tight junction and adherens junction breakdown in a swine model of cardiopulmonary resuscitation

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    Li, Jiebin; Li, Chunsheng; Yuan, Wei; Wu, Junyuan; Li, Jie; Li, Zhenhua; Zhao, Yongzhen

    2017-01-01

    Mild hypothermia improves survival and neurological recovery after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). However, the mechanism underlying this phenomenon is not fully elucidated. The aim of this study was to determine whether mild hypothermia alleviates early blood–brain barrier (BBB) disruption. We investigated the effects of mild hypothermia on neurologic outcome, survival rate, brain water content, BBB permeability and changes in tight junctions (TJs) and adherens junctions (AJs) after CA and CPR. Pigs were subjected to 8 min of untreated ventricular fibrillation followed by CPR. Mild hypothermia (33°C) was intravascularly induced and maintained at this temperature for 12 h, followed by active rewarming. Mild hypothermia significantly reduced cortical water content, decreased BBB permeability and attenuated TJ ultrastructural and basement membrane breakdown in brain cortical microvessels. Mild hypothermia also attenuated the CPR-induced decreases in TJ (occludin, claudin-5, ZO-1) and AJ (VE-cadherin) protein and mRNA expression. Furthermore, mild hypothermia decreased the CA- and CPR-induced increases in matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) expression and increased angiogenin-1 (Ang-1) expression. Our findings suggest that mild hypothermia attenuates the CA- and resuscitation-induced early brain oedema and BBB disruption, and this improvement might be at least partially associated with attenuation of the breakdown of TJ and AJ, suppression of MMP-9 and VEGF expression, and upregulation of Ang-1 expression. PMID:28355299

  2. CMTM3 (CKLF-Like Marvel Transmembrane Domain 3) Mediates Angiogenesis by Regulating Cell Surface Availability of VE-Cadherin in Endothelial Adherens Junctions.

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    Chrifi, Ihsan; Louzao-Martinez, Laura; Brandt, Maarten; van Dijk, Christian G M; Burgisser, Petra; Zhu, Changbin; Kros, Johan M; Duncker, Dirk J; Cheng, Caroline

    2017-06-01

    Decrease in VE-cadherin adherens junctions reduces vascular stability, whereas disruption of adherens junctions is a requirement for neovessel sprouting during angiogenesis. Endocytosis plays a key role in regulating junctional strength by altering bioavailability of cell surface proteins, including VE-cadherin. Identification of new mediators of endothelial endocytosis could enhance our understanding of angiogenesis. Here, we assessed the function of CMTM3 (CKLF-like MARVEL transmembrane domain 3), which we have previously identified as highly expressed in Flk1(+) endothelial progenitor cells during embryonic development. Using a 3-dimensional coculture of human umbilical vein endothelial cells-GFP (green fluorescent protein) and pericytes-RFP (red fluorescent protein), we demonstrated that siRNA-mediated CMTM3 silencing in human umbilical vein endothelial cells impairs angiogenesis. In vivo CMTM3 inhibition by morpholino injection in developing zebrafish larvae confirmed that CMTM3 expression is required for vascular sprouting. CMTM3 knockdown in human umbilical vein endothelial cells does not affect proliferation or migration. Intracellular staining demonstrated that CMTM3 colocalizes with early endosome markers EEA1 (early endosome marker 1) and Clathrin(+) vesicles and with cytosolic VE-cadherin in human umbilical vein endothelial cells. Adenovirus-mediated CMTM3 overexpression enhances endothelial endocytosis, shown by an increase in Clathrin(+), EEA1(+), Rab11(+), Rab5(+), and Rab7(+) vesicles. CMTM3 overexpression enhances, whereas CMTM3 knockdown decreases internalization of cell surface VE-cadherin in vitro. CMTM3 promotes loss of endothelial barrier function in thrombin-induced responses, shown by transendothelial electric resistance measurements in vitro. In this study, we have identified a new regulatory function for CMTM3 in angiogenesis. CMTM3 is involved in VE-cadherin turnover and is a regulator of the cell surface pool of VE-cadherin. Therefore

  3. A vertebrate-specific Chp-PAK-PIX pathway maintains E-cadherin at adherens junctions during zebrafish epiboly.

    Science.gov (United States)

    Tay, Hwee Goon; Ng, Yuen Wai; Manser, Ed

    2010-04-12

    In early vertebrate development, embryonic tissues modulate cell adhesiveness and acto-myosin contractility to correctly orchestrate the complex processes of gastrulation. E-cadherin (E-cadh) is the earliest expressed cadherin and is needed in the mesendodermal progenitors for efficient migration. Regulatory mechanisms involving directed E-cadh trafficking have been invoked downstream of Wnt11/5 signaling. This non-canonical Wnt pathway regulates RhoA-ROK/DAAM1 to control the acto-myosin network. However, in this context nothing is known of the intracellular signals that participate in the correct localization of E-cadh, other than a need for Rab5c signaling. By studying loss of Chp induced by morpholino-oligonucleotide injection in zebrafish, we find that the vertebrate atypical Rho-GTPase Chp is essential for the proper disposition of cells in the early embryo. The underlying defect is not leading edge F-actin assembly (prominent in the cells of the envelope layer), but rather the failure to localize E-cadh and beta-catenin at the adherens junctions. Loss of Chp results in delayed epiboly that can be rescued by mRNA co-injection, and phenocopies zebrafish E-cadh mutants. This new signaling pathway involves activation of an effector kinase PAK, and involvement of the adaptor PAK-interacting exchange factor PIX. Loss of signaling by any of the three components results in similar underlying defects, which is most prominent in the epithelial-like envelope layer. Our current study uncovers a developmental pathway involving Chp/PAK/PIX signaling, which helps co-ordinate E-cadh disposition to promote proper cell adhesiveness, and coordinate movements of the three major cell layers in epiboly. Our data shows that without Chp signaling, E-cadh shifts to intracellular vesicles rather than the adhesive contacts needed for directed cell movement. These events may mirror the requirement for PAK2 signaling essential for the proper formation of the blood-brain barrier.

  4. 'Special K' and a Loss of Cell-To-Cell Adhesion in Proximal Tubule-Derived Epithelial Cells: Modulation of the Adherens Junction Complex by Ketamine

    Science.gov (United States)

    Hills, Claire E.; Jin, Tianrong; Siamantouras, Eleftherios; Liu, Issac K-K; Jefferson, Kieran P.; Squires, Paul E.

    2013-01-01

    Ketamine, a mild hallucinogenic class C drug, is the fastest growing ‘party drug’ used by 16–24 year olds in the UK. As the recreational use of Ketamine increases we are beginning to see the signs of major renal and bladder complications. To date however, we know nothing of a role for Ketamine in modulating both structure and function of the human renal proximal tubule. In the current study we have used an established model cell line for human epithelial cells of the proximal tubule (HK2) to demonstrate that Ketamine evokes early changes in expression of proteins central to the adherens junction complex. Furthermore we use AFM single-cell force spectroscopy to assess if these changes functionally uncouple cells of the proximal tubule ahead of any overt loss in epithelial cell function. Our data suggests that Ketamine (24–48 hrs) produces gross changes in cell morphology and cytoskeletal architecture towards a fibrotic phenotype. These physical changes matched the concentration-dependent (0.1–1 mg/mL) cytotoxic effect of Ketamine and reflect a loss in expression of the key adherens junction proteins epithelial (E)- and neural (N)-cadherin and β-catenin. Down-regulation of protein expression does not involve the pro-fibrotic cytokine TGFβ, nor is it regulated by the usual increase in expression of Slug or Snail, the transcriptional regulators for E-cadherin. However, the loss in E-cadherin can be partially rescued pharmacologically by blocking p38 MAPK using SB203580. These data provide compelling evidence that Ketamine alters epithelial cell-to-cell adhesion and cell-coupling in the proximal kidney via a non-classical pro-fibrotic mechanism and the data provides the first indication that this illicit substance can have major implications on renal function. Understanding Ketamine-induced renal pathology may identify targets for future therapeutic intervention. PMID:24009666

  5. Nectin/PRR: an immunoglobulin-like cell adhesion molecule recruited to cadherin-based adherens junctions through interaction with Afadin, a PDZ domain-containing protein.

    Science.gov (United States)

    Takahashi, K; Nakanishi, H; Miyahara, M; Mandai, K; Satoh, K; Satoh, A; Nishioka, H; Aoki, J; Nomoto, A; Mizoguchi, A; Takai, Y

    1999-05-03

    We have isolated a novel actin filament-binding protein, named afadin, localized at cadherin-based cell-cell adherens junctions (AJs) in various tissues and cell lines. Afadin has one PDZ domain, three proline-rich regions, and one actin filament-binding domain. We found here that afadin directly interacted with a family of the immunoglobulin superfamily, which was isolated originally as the poliovirus receptor-related protein (PRR) family consisting of PRR1 and -2, and has been identified recently to be the alphaherpes virus receptor. PRR has a COOH-terminal consensus motif to which the PDZ domain of afadin binds. PRR and afadin were colocalized at cadherin-based cell-cell AJs in various tissues and cell lines. In E-cadherin-expressing EL cells, PRR was recruited to cadherin-based cell-cell AJs through interaction with afadin. PRR showed Ca2+-independent cell-cell adhesion activity. These results indicate that PRR is a cell-cell adhesion molecule of the immunoglobulin superfamily which is recruited to cadherin-based cell-cell AJs through interaction with afadin. We rename PRR as nectin (taken from the Latin word "necto" meaning "to connect").

  6. Structural alteration of tight and adherens junctions in villous and crypt epithelium of the small and large intestine of conventional nursing piglets infected with porcine epidemic diarrhea virus.

    Science.gov (United States)

    Jung, Kwonil; Eyerly, Bryan; Annamalai, Thavamathi; Lu, Zhongyan; Saif, Linda J

    2015-06-12

    Integrity of the intestinal epithelium is critical for proper functioning of the barrier that regulates absorption of water and restricts uptake of luminal bacteria. It is maintained mainly by tight junctions (TJs) and adherens junctions (AJs). We conducted immunofluorescence (IF) staining for in situ identification of zonula occludin (ZO)-1 proteins for TJ and E-Cadherin proteins for AJ in the small and large intestinal villous and crypt epithelium of nursing pigs infected with porcine epidemic diarrhea virus (PEDV). Twenty 9-day-old piglets [PEDV-infected (n=9) and Mock (n=11)] from PEDV seronegative sows, were orally inoculated [8.9 log₁₀ genomic equivalents/pig] with PEDV PC21A strain or mock. At post-inoculation days (PIDs) 1-5, infected pigs showed severe watery diarrhea and/or vomiting and severe atrophic enteritis. By immunohistochemistry, PEDV antigens were evident in enterocytes lining the villous epithelium. At PIDs 1-5, PEDV-infected pigs exhibited mildly to extensively disorganized, irregular distribution and reduced expression of ZO-1 or E-Cadherin in villous, but not crypt epithelial cells of the jejunum and ileum, but not in the large intestine, when compared to the negative controls. The structural destruction and disorganization of TJ and AJ were extensive in PEDV-infected pigs at PIDs 1-3, but then appeared to reversibly recover at PID 5, as evident by increased numbers of ZO-1-positive epithelial cells and markedly improved appearance of E-Cadherin-positive villous epithelium. Our results suggest a possible involvement of structurally impaired TJ and AJ in the pathogenesis of PEDV, potentially leading to secondary bacterial infections.

  7. Cigarette smoke disrupts the integrity of airway adherens junctions through the aberrant interaction of p120-catenin with the cytoplasmic tail of MUC1

    Science.gov (United States)

    Zhang, Lili; Gallup, Marianne; Zlock, Lorna; Basbaum, Carol; Finkbeiner, Walter E.; McNamara, Nancy A.

    2014-01-01

    Adherens junctions (AJs) containing epithelial cadherin (E-cad) bound to p120-catenin (p120ctn) and β-catenin (β-ctn) play a crucial role in regulating cell–cell adhesion. Cigarette smoke abrogates cell–cell adhesion between epithelial cells by disrupting E-cad, a hallmark of epithelial–mesenchymal transition (EMT), yet the underlying mechanism remains unknown. We used an organotypic culture of primary human bronchial epithelial (HBE) cells treated with smoke-concentrated medium (Smk) to establish an essential role for the interaction between p120ctn and the cytoplasmic tail of MUC1 (MUC1-CT) in regulating E-cad disruption. Within the first 4 h of smoke exposure, apical MUC1-CT repositioned to the basolateral membrane of pseudo-stratified HBE cells, where it interacted with p120ctn. A time-dependent increase in MUC1-CT/p120ctn complexes occurred in conjunction with a time-dependent dissociation of p120ctn/E-cad/β-ctn complexes, as well as the coordinated degradation of p120ctn and E-cad. Interestingly, Smk induced a similar interaction between MUC1-CT and β-ctn, but this occurred 44 h after MUC1-CT’s initial interaction with p120ctn, and well after the AJs were destroyed. Blocking MUC1-CT’s interaction with p120ctn using a MUC1-CT dominant-negative peptide, PMIP, successfully abolished Smk’s disruptive effects on AJs and recovered apical-basolateral polarity of HBE cells. The MUC1-CT/p120ctn interaction was highly dependent on EGFR/Src/Jnk-mediated tyrosine phosphorylation (TyrP) of MUC1-CT. Accordingly, EGFR, Src or Jnk inhibitors (AG1478, PP2, SP600125, respectively) abrogated Smk-induced MUC1-CT-TyrP, MUC1-CT/p120ctn interaction, AJ disruption, and loss of cellular polarity. Our work identified MUC1-CT and p120ctn as important regulators of epithelial polarity and cell-cell adhesion during a smoke-induced EMT-like process. Novel therapeutics designed to inhibit MUC1-CT/p120ctn complex formation may prevent EMT in the smoker’s airway. PMID

  8. Reduced expression of adherens and gap junction proteins can have a fundamental role in the development of heart failure following cardiac hypertrophy in rats.

    Science.gov (United States)

    dos Santos, Daniele O; Blefari, Valdecir; Prado, Fernanda P; Silva, Carlos A; Fazan, Rubens; Salgado, Helio C; Ramos, Simone G; Prado, Cibele M

    2016-02-01

    Hypertension causes cardiac hypertrophy, cardiac dysfunction and heart failure (HF). The mechanisms implicated in the transition from compensated to decompensated cardiac hypertrophy are not fully understood. This study was aimed to investigate whether alterations in the expression of intercalated disk proteins could contribute to the transition of compensated cardiac hypertrophy to dilated heart development that culminates in HF. Male rats were submitted to abdominal aortic constriction and at 90 days post surgery (dps), three groups were observed: sham-operated animals (controls), animals with hypertrophic hearts (HH) and animals with hypertrophic + dilated hearts (HD). Blood pressure was evaluated. The hearts were collected and Western blot and immunofluorescence were performed to desmoglein-2, desmocollin-2, N-cadherin, plakoglobin, Bcatenin, and connexin-43. Cardiac systolic function was evaluated using the Vevo 2100 ultrasound system. Data were considered significant when p b 0.05. Seventy percent of the animals presented with HH and 30% were HD at 90 dps. The blood pressure increased in both groups. The amount of desmoglein-2 and desmocollin-2 expression was increased in both groups and no difference was observed in either group. The expression of N-cadherin, plakoglobin and B-catenin increased in the HHgroup and decreased in the HDgroup; and connexin-43 decreased only in theHDgroup. Therewas no difference between the ejection fraction and fractional shortening at 30 and 60 dps; however, they were decreased in the HD group at 90 dps. We found that while some proteins have increased expression accompanied by the increase in the cell volume associated with preserved systolic cardiac function in theHHgroup, these same proteins had decreased expression evenwithout significant reduction in the cell volume associated with decreased systolic cardiac function in HD group. The increased expression of desmoglein-2 and desmocollin-2 in both the HH and HD groups could

  9. On Determination of Pollution in Urban Junction, Caused by Vehicles

    Directory of Open Access Journals (Sweden)

    Asllan Hajderi

    2013-04-01

    Full Text Available In this study, given the determination of the pollution quantity from vehicles in an urbanjunction in order to reduce the pollution level and fuel. The pollution caused by vehicles,it is taken based on production years within the EC directives. Types of vehiclescirculating are determined based on vehicles state, divided by production years and thetype of engine.For urban junction with roundabout "Zogu Zi", they are performed measurements ofvehicles number, that move in an hour, describing way with slowly and relevant time. Forthis junction it is calculated vehicle speed at the junction and pollution quantity isconverted to g/min and then it is determined the pollution quantity per hour for existingstate of vehicles divided into 5 groups, according to pollution level. For practicalapplication, only vehicles manufactured after 2000 in circulation, it results that can beachieved a pollution reduction at the junction up to 3 times. To realize this, it is proposedthe removal of customs duty for vehicles manufactured after 2001 and establishment ofadditional environmental tax, proportional to the pollution degree for vehicles incirculation.

  10. Forming a stone in pelviureteric junction obstruction: cause or effect?

    Science.gov (United States)

    Stasinou, Theodora; Bourdoumis, Andreas; Masood, Junaid

    2017-01-01

    ABSTRACT Objectives To investigate a possible causal relationship for stone formation in pelviureteric junction obstruction and to outline management options. Materials and Methods A literature search and evidence synthesis was conducted via electronic databases in the English language using the key words pelviureteric junction obstruction; urolithiasis; hyperoxaluria; laparoscopic pyeloplasty; flexible nephroscopy; percutaneous nephrolithotomy, alone or in combination. Relevant articles were analysed to extract conclusions. Results Concomitant pelviureteric junction obstruction (PUJO) and renal lithiasis has been reported only scarcely in the literature. Although PUJO has been extensively studied throughout the years, the presence of calculi in such a patient has not received equal attention and there is still doubt surrounding the pathophysiology and global management. Conclusions Metabolic risk factors appear to play an important role, enough to justify metabolic evaluation in these patients. Urinary stasis and infection are well known factors predisposing to lithiasis and contribute to some extent. The choice for treatment is not always straightforward. Management should be tailored according to degree of obstruction, renal function, patient symptoms and stone size. Simultaneous treatment is feasible with the aid of minimally invasive operative techniques and laparoscopy in particular.

  11. Pyelonephritis caused by Actinobaculum schaalii in a child with pyeloureteral junction obstruction.

    NARCIS (Netherlands)

    Pajkrt, D.; Simoons - Smit, A.M.; Savelkoul, P.H.M.; Hoek, van den J.; Hack, WW; Furth, van A.M.

    2003-01-01

    Reported here is the case of a 5-year old boy with a pyeloureteral junction (PUJ) obstruction and pyelonephritis caused by Actinobaculum schaalii, an Actinomyces-like organism. Pyelonephritis or any other urinary tract infection caused by Actinobaculum schaalii has not been described in children

  12. Do cell junction protein mutations cause an airway phenotype in mice or humans?

    Science.gov (United States)

    Chang, Eugene H; Pezzulo, Alejandro A; Zabner, Joseph

    2011-08-01

    Cell junction proteins connect epithelial cells to each other and to the basement membrane. Genetic mutations of these proteins can cause alterations in some epithelia leading to varied phenotypes such as deafness, renal disease, skin disorders, and cancer. This review examines if genetic mutations in these proteins affect the function of lung airway epithelia. We review cell junction proteins with examples of disease mutation phenotypes in humans and in mouse knockout models. We also review which of these genes are expressed in airway epithelium by microarray expression profiling and immunocytochemistry. Last, we present a comprehensive literature review to find the lung phenotype when cell junction and adhesion genes are mutated or subject to targeted deletion. We found that in murine models, targeted deletion of cell junction and adhesion genes rarely result in a lung phenotype. Moreover, mutations in these genes in humans have no obvious lung phenotype. Our research suggests that simply because a cell junction or adhesion protein is expressed in an organ does not imply that it will exhibit a drastic phenotype when mutated. One explanation is that because a functioning lung is critical to survival, redundancy in the system is expected. Therefore mutations in a single gene might be compensated by a related function of a similar gene product. Further studies in human and animal models will help us understand the overlap in the function of cell junction gene products. Finally, it is possible that the human lung phenotype is subtle and has not yet been described.

  13. Reversible cardiogenic shock caused by atrioventricular junctional rhythm after percutaneous coronary intervention

    Institute of Scientific and Technical Information of China (English)

    Jun Wang; Qi-Gao Zhang; Xiao-Min Cai; Li-Jun Wang; Jian-Bin Gong; Shi-Sen Jiang

    2012-01-01

    An 82-year-old female patient undergoing cardiogenic shock caused by atrioventricular junctional rhythm immediately after percutaneous coronary intervention (PCI) is described. Pharmacotherapy was invalid, and subsequent application of atrial pacing reversed the cardiogenic shock. PCI-related injury of sinuatrial nodal artery leading to acute atrial contractility loss, accompanied by atrioventricular junctional arrhythmia, was diagnosed. We recommend that preoperative risk evaluation be required for multi-risk patients. Likewise, emergent measures should to be established in advance. This case reminds us that atrial pacing can be an optimal management technique once cardiogenic shock has occurred.

  14. Gallstone impacted in the rectosigmoid junction causing a biliary ileus and a sigmoid perforation.

    Science.gov (United States)

    Van Kerschaver, O; Van Maele, V; Vereecken, L; Kint, M

    2009-01-01

    A gallstone ileus is an unusual form of bowel obstruction. Colonic gallstone ileus is rare, difficult to diagnose, and still has a high mortality rate. We present a case of biliary ileus caused by an impacted gallstone, causing necrosis and perforation of the rectosigmoid junction. A Hartmann's procedure was performed to treat the perforation and the obstruction. Cholecystectomy and closure of the cholecysto-colonic fistula were delayed until restoration of the intestinal continuity.

  15. West Nile virus infection causes endocytosis of a specific subset of tight junction membrane proteins.

    Directory of Open Access Journals (Sweden)

    Zaikun Xu

    Full Text Available West Nile virus (WNV is a blood-borne pathogen that causes systemic infections and serious neurological disease in human and animals. The most common route of infection is mosquito bites and therefore, the virus must cross a number of polarized cell layers to gain access to organ tissue and the central nervous system. Resistance to trans-cellular movement of macromolecules between epithelial and endothelial cells is mediated by tight junction complexes. While a number of recent studies have documented that WNV infection negatively impacts the barrier function of tight junctions, the intracellular mechanism by which this occurs is poorly understood. In the present study, we report that endocytosis of a subset of tight junction membrane proteins including claudin-1 and JAM-1 occurs in WNV infected epithelial and endothelial cells. This process, which ultimately results in lysosomal degradation of the proteins, is dependent on the GTPase dynamin and microtubule-based transport. Finally, infection of polarized cells with the related flavivirus, Dengue virus-2, did not result in significant loss of tight junction membrane proteins. These results suggest that neurotropic flaviviruses such as WNV modulate the host cell environment differently than hemorrhagic flaviviruses and thus may have implications for understanding the molecular basis for neuroinvasion.

  16. Glutamine supplementation attenuates ethanol-induced disruption of apical junctional complexes in colonic epithelium and ameliorates gut barrier dysfunction and fatty liver in mice.

    Science.gov (United States)

    Chaudhry, Kamaljit K; Shukla, Pradeep K; Mir, Hina; Manda, Bhargavi; Gangwar, Ruchika; Yadav, Nikki; McMullen, Megan; Nagy, Laura E; Rao, RadhaKrishna

    2016-01-01

    Previous in vitro studies showed that glutamine (Gln) prevents acetaldehyde-induced disruption of tight junctions and adherens junctions in Caco-2 cell monolayers and human colonic mucosa. In the present study, we evaluated the effect of Gln supplementation on ethanol-induced gut barrier dysfunction and liver injury in mice in vivo. Ethanol feeding caused a significant increase in inulin permeability in distal colon. Elevated permeability was associated with a redistribution of tight junction and adherens junction proteins and depletion of detergent-insoluble fractions of these proteins, suggesting that ethanol disrupts apical junctional complexes in colonic epithelium and increases paracellular permeability. Ethanol-induced increase in colonic mucosal permeability and disruption of junctional complexes were most severe in mice fed Gln-free diet. Gln supplementation attenuated ethanol-induced mucosal permeability and disruption of tight junctions and adherens junctions in a dose-dependent manner, indicating the potential role of Gln in nutritional intervention to alcoholic tissue injury. Gln supplementation dose-dependently elevated reduced-protein thiols in colon without affecting the level of oxidized-protein thiols. Ethanol feeding depleted reduced protein thiols and elevated oxidized protein thiols. Ethanol-induced protein thiol oxidation was most severe in mice fed with Gln-free diet and absent in mice fed with Gln-supplemented diet, suggesting that antioxidant effect is one of the likely mechanisms involved in Gln-mediated amelioration of ethanol-induced gut barrier dysfunction. Ethanol feeding elevated plasma transaminase and liver triglyceride, which was accompanied by histopathologic lesions in the liver; ethanol-induced liver damage was attenuated by Gln supplementation. These results indicate that Gln supplementation ameliorates alcohol-induced gut and liver injury.

  17. Measurement and understanding of single-molecule break junction rectification caused by asymmetric contacts.

    Science.gov (United States)

    Wang, Kun; Zhou, Jianfeng; Hamill, Joseph M; Xu, Bingqian

    2014-08-01

    The contact effects of single-molecule break junctions on rectification behaviors were experimentally explored by a systematic control of anchoring groups of 1,4-disubstituted benzene molecular junctions. Single-molecule conductance and I-V characteristic measurements reveal a strong correlation between rectifying effects and the asymmetry in contacts. Analysis using energy band models and I-V calculations suggested that the rectification behavior is mainly caused by asymmetric coupling strengths at the two contact interfaces. Fitting of the rectification ratio by a modified Simmons model we developed suggests asymmetry in potential drop across the asymmetric anchoring groups as the mechanism of rectifying I-V behavior. This study provides direct experimental evidence and sheds light on the mechanisms of rectification behavior induced simply by contact asymmetry, which serves as an aid to interpret future single-molecule electronic behavior involved with asymmetric contact conformation.

  18. Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 in a dog

    Directory of Open Access Journals (Sweden)

    Harumichi Itoh

    2017-03-01

    Full Text Available Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 were diagnosed in a 6-month-old female Pomeranian with tetraplegia as a clinical sign. Lateral survey radiography of the neck with flexion revealed atlantoaxial subluxation with ventral subluxation of C2. Computed tomography revealed absence of dens and atlanto-occipital overlapping. Magnetic resonance imaging showed compression of the spinal cord and indentation of caudal cerebellum. The diagnosis was Chiari-like malformation, atlantoaxial subluxation with ventral displacement of C2, atlanto-occipital overlapping, and syringomyelia. The dog underwent foramen magnum decompression, dorsal laminectomy of C1, and ventral fixation of the atlantoaxial joint. Soon after the operation, voluntary movements of the legs were recovered. Finally, the dog could stand and walk without assistance. The dog had complicated malformations at the craniocervical junction but foramen magnum decompression and dorsal laminectomy for Chiari-like malformation, and ventral fixation for atlantoaxial subluxation resulted in an excellent clinical outcome.

  19. A membrane fusion protein αSNAP is a novel regulator of epithelial apical junctions.

    Directory of Open Access Journals (Sweden)

    Nayden G Naydenov

    Full Text Available Tight junctions (TJs and adherens junctions (AJs are key determinants of the structure and permeability of epithelial barriers. Although exocytic delivery to the cell surface is crucial for junctional assembly, little is known about the mechanisms controlling TJ and AJ exocytosis. This study was aimed at investigating whether a key mediator of exocytosis, soluble N-ethylmaleimide sensitive factor (NSF attachment protein alpha (αSNAP, regulates epithelial junctions. αSNAP was enriched at apical junctions in SK-CO15 and T84 colonic epithelial cells and in normal human intestinal mucosa. siRNA-mediated knockdown of αSNAP inhibited AJ/TJ assembly and establishment of the paracellular barrier in SK-CO15 cells, which was accompanied by a significant down-regulation of p120-catenin and E-cadherin expression. A selective depletion of p120 catenin effectively disrupted AJ and TJ structure and compromised the epithelial barrier. However, overexpression of p120 catenin did not rescue the defects of junctional structure and permeability caused by αSNAP knockdown thereby suggesting the involvement of additional mechanisms. Such mechanisms did not depend on NSF functions or induction of cell death, but were associated with disruption of the Golgi complex and down-regulation of a Golgi-associated guanidine nucleotide exchange factor, GBF1. These findings suggest novel roles for αSNAP in promoting the formation of epithelial AJs and TJs by controlling Golgi-dependent expression and trafficking of junctional proteins.

  20. Utilizing ultrasonography in the diagnosis of pediatric fibroepithelial polyps causing ureteropelvic junction obstruction.

    Science.gov (United States)

    Wang, Xiao Man; Jia, Li Qun; Wang, Yu; Wang, Ning

    2012-09-01

    Fibroepithelial polyps are a rare cause of ureteropelvic junction (UPJ) obstruction in children. Preoperative US diagnosis of fibroepithelial polyps is infrequently reported, with intravenous pylogram and retrograde pyelography being most commonly used for diagnosis. To recommend the most accurate process for diagnosing this disease in children by assessing a modified ultrasonographic procedure for the diagnosis of fibroepithelial polyps. A retrospective review of US and IVP imaging studies performed in surgically and histologically confirmed cases of fibroepithelial polyps in children. Each child was asked to drink as much water as possible 30 min before the US testing. For US, the renal pelvis, UPJ and the proximal ureter were inspected for an echogenic mass resulting in hydronephrosis. For IVP studies, abdominal plain films were performed at 7, 15 and 30 min following contrast injection. Thirty-five children, 34 boys and 1 girl, had confirmed fibroepithelial polyps. The children ranged in age from 3 to 14 years (mean age 9 years). Clinical presentation included intermittent vague abdominal pain (100%) and/or hematuria (9.7%) for a period ranging from 1 month to 5 years. Of the 35 children (37 polyps), 21 (23 polyps) were correctly diagnosed preoperatively with US, establishing a 62.2% (23/37) US accuracy rate. Twenty polyps were seen on the left, three on the right and two children had bilateral polyps. The masses were all mildly echogenic with defined edges. Eight children (9 polyps) had an IVP consistent with fibroepithelial polyps giving IVP an accuracy rate of 24.3% (9/37). US is an effective screening tool for identifying fibroepithelial polyps causing UPJ obstruction in children.

  1. Connexin43 mutation causes heterogeneous gap junction loss and sudden infant death.

    Science.gov (United States)

    Van Norstrand, David W; Asimaki, Angeliki; Rubinos, Clio; Dolmatova, Elena; Srinivas, Miduturu; Tester, David J; Saffitz, Jeffrey E; Duffy, Heather S; Ackerman, Michael J

    2012-01-24

    An estimated 10% to 15% of sudden infant death syndrome (SIDS) cases may stem from channelopathy-mediated lethal arrhythmias. Loss of the GJA1-encoded gap junction channel protein connexin43 is known to underlie formation of lethal arrhythmias. GJA1 mutations have been associated with cardiac diseases, including atrial fibrillation. Therefore, GJA1 is a plausible candidate gene for premature sudden death. GJA1 open reading frame mutational analysis was performed with polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing on DNA from 292 SIDS cases. Immunofluorescence and dual whole-cell patch-clamp studies were performed to determine the functionality of mutant gap junctions. Immunostaining for gap junction proteins was performed on SIDS-associated paraffin-embedded cardiac tissue. Two rare, novel missense mutations, E42K and S272P, were detected in 2 of 292 SIDS cases, a 2-month-old white boy and a 3-month-old white girl, respectively. Analysis of the E42K victim's parental DNA demonstrated a de novo mutation. Both mutations involved highly conserved residues and were absent in >1000 ethnically matched reference alleles. Immunofluorescence demonstrated no trafficking abnormalities for either mutation, and S272P demonstrated wild-type junctional conductance. However, junctional conductance measurements for the E42K mutation demonstrated a loss of function not rescued by wild type. Moreover, the E42K victim's cardiac tissue demonstrated a mosaic immunostaining pattern for connexin43 protein. This study provides the first molecular and functional evidence implicating a GJA1 mutation as a novel pathogenic substrate for SIDS. E42K-connexin43 demonstrated a trafficking-independent reduction in junctional coupling in vitro and a mosaic pattern of mutational DNA distribution in deceased cardiac tissue, suggesting a novel mechanism of connexin43-associated sudden death.

  2. Chondromyxoid fibroma invasion of the transverse-sigmoid sinus junction causing posterior fossa hemorrhage.

    Science.gov (United States)

    Hersh, David S; Firempong, Alexander O; Chesler, David; Castellani, Rudolph J; Woodworth, Graeme F

    2016-02-01

    We report a 50-year-old woman with a chondromyxoid fibroma of the occipital bone, who presented with a cerebellar hemorrhage due to invasion of the adjacent sinus. Chondromyxoid fibromas are benign cartilaginous tumors. However, this case represents the first example, to our knowledge, of a chondromyxoid fibroma invading the transverse-sigmoid junction, resulting in intracranial hemorrhage. Our report highlights that the location of an intracranial chondromyxoid fibroma is an important factor in guiding surgical management.

  3. Connexin26 Mutations Causing Palmoplantar Keratoderma and Deafness Interact with Connexin43, Modifying Gap Junction and Hemichannel Properties.

    Science.gov (United States)

    Shuja, Zunaira; Li, Leping; Gupta, Shashank; Meşe, Gülistan; White, Thomas W

    2016-01-01

    Mutations in GJB2 (connexin [Cx]26) cause either deafness or deafness associated with skin diseases. That different disorders can be caused by distinct mutations within the same gene suggests that unique channel activities are influenced by each class of mutation. We have examined the functional characteristics of two human mutations, Cx26-H73R and Cx26-S183F, causing palmoplantar keratoderma (PPK) and deafness. Both failed to form gap junction channels or hemichannels when expressed alone. Coexpression of the mutants with wild-type Cx43 showed a transdominant inhibition of Cx43 gap junction channels, without reductions in Cx43 protein synthesis. In addition, the presence of mutant Cx26 shifted Cx43 channel gating and kinetics toward a more Cx26-like behavior. Coimmunoprecipitation showed Cx43 being pulled down more efficiently with mutant Cx26 than wild-type, confirming the enhanced formation of heteromeric connexons. Finally, the formation of heteromeric connexons resulted in significantly increased Cx43 hemichannel activity in the presence of Cx26 mutants. These findings suggest a common mechanism whereby Cx26 mutations causing PPK and deafness transdominantly influence multiple functions of wild-type Cx43. They also implicate a role for aberrant hemichannel activity in the pathogenesis of PPK and further highlight an emerging role for Cx43 in genetic skin diseases.

  4. Urothelial Defects from Targeted Inactivation of Exocyst Sec10 in Mice Cause Ureteropelvic Junction Obstructions.

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    Ben Fogelgren

    Full Text Available Most cases of congenital obstructive nephropathy are the result of ureteropelvic junction obstructions, and despite their high prevalence, we have a poor understanding of their etiology and scarcity of genetic models. The eight-protein exocyst complex regulates polarized exocytosis of intracellular vesicles in a large variety of cell types. Here we report generation of a conditional knockout mouse for Sec10, a central component of the exocyst, which is the first conditional allele for any exocyst gene. Inactivation of Sec10 in ureteric bud-derived cells using Ksp1.3-Cre mice resulted in severe bilateral hydronephrosis and complete anuria in newborns, with death occurring 6-14 hours after birth. Sec10 FL/FL;Ksp-Cre embryos developed ureteropelvic junction obstructions between E17.5 and E18.5 as a result of degeneration of the urothelium and subsequent overgrowth by surrounding mesenchymal cells. The urothelial cell layer that lines the urinary tract must maintain a hydrophobic luminal barrier again urine while remaining highly stretchable. This barrier is largely established by production of uroplakin proteins that are transported to the apical surface to establish large plaques. By E16.5, Sec10 FL/FL;Ksp-Cre ureter and pelvic urothelium showed decreased uroplakin-3 protein at the luminal surface, and complete absence of uroplakin-3 by E17.5. Affected urothelium at the UPJ showed irregular barriers that exposed the smooth muscle layer to urine, suggesting this may trigger the surrounding mesenchymal cells to overgrow the lumen. Findings from this novel mouse model show Sec10 is critical for the development of the urothelium in ureters, and provides experimental evidence that failure of this urothelial barrier may contribute to human congenital urinary tract obstructions.

  5. Urothelial Defects from Targeted Inactivation of Exocyst Sec10 in Mice Cause Ureteropelvic Junction Obstructions.

    Science.gov (United States)

    Fogelgren, Ben; Polgar, Noemi; Lui, Vanessa H; Lee, Amanda J; Tamashiro, Kadee-Kalia A; Napoli, Josephine Andrea; Walton, Chad B; Zuo, Xiaofeng; Lipschutz, Joshua H

    2015-01-01

    Most cases of congenital obstructive nephropathy are the result of ureteropelvic junction obstructions, and despite their high prevalence, we have a poor understanding of their etiology and scarcity of genetic models. The eight-protein exocyst complex regulates polarized exocytosis of intracellular vesicles in a large variety of cell types. Here we report generation of a conditional knockout mouse for Sec10, a central component of the exocyst, which is the first conditional allele for any exocyst gene. Inactivation of Sec10 in ureteric bud-derived cells using Ksp1.3-Cre mice resulted in severe bilateral hydronephrosis and complete anuria in newborns, with death occurring 6-14 hours after birth. Sec10 FL/FL;Ksp-Cre embryos developed ureteropelvic junction obstructions between E17.5 and E18.5 as a result of degeneration of the urothelium and subsequent overgrowth by surrounding mesenchymal cells. The urothelial cell layer that lines the urinary tract must maintain a hydrophobic luminal barrier again urine while remaining highly stretchable. This barrier is largely established by production of uroplakin proteins that are transported to the apical surface to establish large plaques. By E16.5, Sec10 FL/FL;Ksp-Cre ureter and pelvic urothelium showed decreased uroplakin-3 protein at the luminal surface, and complete absence of uroplakin-3 by E17.5. Affected urothelium at the UPJ showed irregular barriers that exposed the smooth muscle layer to urine, suggesting this may trigger the surrounding mesenchymal cells to overgrow the lumen. Findings from this novel mouse model show Sec10 is critical for the development of the urothelium in ureters, and provides experimental evidence that failure of this urothelial barrier may contribute to human congenital urinary tract obstructions.

  6. Analysis of single-event upset of magnetic tunnel junction used in spintronic circuits caused by radiation-induced current

    Energy Technology Data Exchange (ETDEWEB)

    Sakimura, N., E-mail: n-sakimura@ap.jp.nec.com [Green Platform Research Laboratories, NEC Corporation, Tsukuba (Japan); Research Institute of Electrical Communication, Tohoku University, Sendai (Japan); Nebashi, R.; Sugibayashi, T. [Green Platform Research Laboratories, NEC Corporation, Tsukuba (Japan); Natsui, M.; Hanyu, T. [Research Institute of Electrical Communication, Tohoku University, Sendai (Japan); Ohno, H. [Research Institute of Electrical Communication, Tohoku University, Sendai (Japan); Center for Spintronics Integrated Systems, Tohoku University, Sendai (Japan); WPI Advanced Institute for Materials Research, Tohoku University, Sendai (Japan)

    2014-05-07

    This paper describes the possibility of a switching upset of a magnetic tunnel junction (MTJ) caused by a terrestrial radiation-induced single-event-upset (SEU) current in spintronic integrated circuits. The current waveforms were simulated by using a 3-D device simulator in a basic circuit including MTJs designed using 90-nm CMOS parameters and design rules. The waveforms have a 400 -μA peak and a 200-ps elapsed time when neutron particles with a linear energy transfer value of 14 MeV cm{sup 2}/mg enter the silicon surface. The authors also found that the SEU current may cause soft errors with a probability of more than 10{sup −12} per event, which was obtained by approximate solution of the ordinary differential equation of switching probability when the intrinsic critical current (I{sub C0}) became less than 30 μA.

  7. Transcriptional mechanisms coordinating tight junction assembly during epithelial differentiation.

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    Boivin, Felix J; Schmidt-Ott, Kai M

    2017-06-01

    Epithelial tissues form a selective barrier via direct cell-cell interactions to separate and establish concentration gradients between the different compartments of the body. Proper function and formation of this barrier rely on the establishment of distinct intercellular junction complexes. These complexes include tight junctions, adherens junctions, desmosomes, and gap junctions. The tight junction is by far the most diverse junctional complex in the epithelial barrier. Its composition varies greatly across different epithelial tissues to confer various barrier properties. Thus, epithelial cells rely on tightly regulated transcriptional mechanisms to ensure proper formation of the epithelial barrier and to achieve tight junction diversity. Here, we review different transcriptional mechanisms utilized during embryogenesis and disease development to promote tight junction assembly and maintenance of intercellular barrier integrity. We focus particularly on the Grainyhead-like transcription factors and ligand-activated nuclear hormone receptors, two central families of proteins in epithelialization. © 2017 New York Academy of Sciences.

  8. Connexins, E-cadherin, Claudin-7 and β-catenin transiently form junctional nexuses during the post-natal mammary gland development.

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    Dianati, Elham; Poiraud, Jérémy; Weber-Ouellette, Anne; Plante, Isabelle

    2016-08-01

    Gap junctions are intercellular channels made of connexins (Cxs) that allow direct communication between adjacent cells. Modulation of Cxs has been associated with abnormal development and function of the mammary gland and breast cancer. However, the mechanisms underlying their expression during normal mammary gland are not yet known. Cxs interact with components of tight and adherens junctions. Thus, we hypothesized that the expression levels of Cxs vary during mammary gland development and are regulated through stage-dependent interactions with members of the tight and adherens junctions. Our specific objectives were to: 1) determine the expression of Cxs and tight and adherens junction proteins throughout development and 2) characterize Cxs interactions with components of tight and adherens junctions. Murine mammary glands were sampled at various developmental stages (pre-pubescent to post-weaning). RT-qPCR and western-blot analyses demonstrated differential expression patterns for all gap (Cx43, Cx32, Cx26, Cx30), tight (Claudin-1, -3, -4, -7) and adherens (β-catenin, E- and P-cadherins) junctions throughout development. Interestingly, co-immunoprecipitation demonstrated interactions between these different types of junctions. Cx30 interacted with Cx26 just at the late pregnancy stage. While Cx43 showed a persistent interaction with β-catenin from virginity to post-weaning, its interactions with E-cadherin and Claudin-7 were transient. Cx32 interacted with Cx26, E-cadherin and β-catenin during lactation. Immunofluorescence results confirmed the existence of a junctional nexus that remodeled during mammary gland development. Together, our results confirm that the expression levels of Cxs vary concomitantly and that Cxs form junctional nexuses with tight and adherens junctions, suggesting the existence of common regulatory pathways.

  9. Giant prolactinoma causing cranio-cervical junction instability: a case report.

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    Zaben, Malik J A; Harrisson, Stuart E; Mathad, N V

    2011-12-01

    Prolactinomas are common secretory pituitary tumours, usually managed with dopamine agonists. There have previously been case reports of rarer giant prolactinomas causing invasion of surrounding structures. We describe a case report of an exceptionally aggressive giant prolactinoma that eroded the occipital condyles causing cranio-cervical joint instability mandating surgical fixation.

  10. Benign Fibroepithelial Polyps: A Rare Cause of Ureteropelvic Junction Obstruction in Children

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    Anitha Ezekiel

    2015-07-01

    Full Text Available FEPs are rare, benign mucosal growths that may cause urinary tract obstruction in both adults and children. We present the case of a ten year old Hispanic male with recurring urinary tract infections and hydronephrosis diagnosed with fibroepithelial polyps (FEPs. Despite multiple radiographic procedures, we were unable to accurately preoperatively diagnose FEPs. Here we demonstrate the difficulties in preoperative diagnosis and suggest that perhaps a combination of US and MRI in the setting of persistent urinary tract infections and flank pain may be the best approach for early diagnosis and conservative management, including less invasive treatment protocols.

  11. Compound inheritance of a low-frequency regulatory SNP and a rare null mutation in exon-junction complex subunit RBM8A causes TAR syndrome

    NARCIS (Netherlands)

    Albers, C.A.; Paul, D.S.; Schulze, H.; Freson, K.; Stephens, J.C.; Smethurst, P.A.; Jolley, J.D.; Cvejic, A.; Kostadima, M.; Bertone, P.; Breuning, M.H.; Debili, N.; Deloukas, P.; Favier, R.; Fiedler, J.; Hobbs, C.M.; Huang, N.; Hurles, M.E.; Kiddle, G.; Krapels, I.; Nurden, P.; Ruivenkamp, C.A.; Sambrook, J.G.; Smith, K.; Stemple, D.L.; Strauss, G.; Thys, C.; Geet, C. van; Newbury-Ecob, R.; Ouwehand, W.H.; Ghevaert, C.

    2012-01-01

    The exon-junction complex (EJC) performs essential RNA processing tasks. Here, we describe the first human disorder, thrombocytopenia with absent radii (TAR), caused by deficiency in one of the four EJC subunits. Compound inheritance of a rare null allele and one of two low-frequency SNPs in the reg

  12. Degeneration of noradrenergic fibres from the locus coeruleus causes tight-junction disorganisation in the rat brain.

    Science.gov (United States)

    Kalinin, Sergey; Feinstein, Douglas L; Xu, Hao-Liang; Huesa, Gema; Pelligrino, Dale A; Galea, Elena

    2006-12-01

    Although functional studies demonstrate that noradrenaline controls the permeability of the blood-brain barrier, it has never been determined whether this neurotransmitter regulates the tight junction (TJ) assembly that confers the barrier property to brain microvessels. We thus tested in rats the effect of pharmacological depletion of noradrenaline with the noradrenergic toxin DSP4 (5 mg/kg) on the expression of the TJ proteins zonula occludens-1 (ZO1) and occludin. The effectiveness of the lesion was confirmed by tyrosine hydroxylase immunoreactivity, which showed noradrenergic fibre reduction accompanied by debris and swollen fibres in DSP4-treated brains. Noradrenergic fibre degeneration caused: (i) gliosis; (ii) disappearance of TJ proteins in vascular cell-to-cell contacts (49.9 and 38.3% reductions for occludin and ZO1, respectively); (iii) a 49.2% decrease in total ZO1 protein, measured by Western blot analysis, parallel to a 39.5% decrease in ZO1 mRNA, measured by real-time PCR; and (iv) a relative increase in the beta occludin isoform (62.9%), with no change in total occludin protein or mRNA. The expression of endothelial brain antigen, a marker of a functionally competent brain endothelium, was also reduced. We conclude that damage to the ascending fibres from the locus coeruleus caused TJ disruption and gliosis, a sign of inflammation. These results imply that the locus coeruleus degeneration reported in Alzheimer's and Parkinson's diseases may contribute to these disorders by causing blood-brain barrier dysfunction. Whether the vascular damage is the result of impaired noradrenergic transmission or secondary to the inflammatory reaction remains to be determined.

  13. THE CELULAR JUNCTIONS AND THE EMERGENCE OF ANIMALS

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    Urquiza-Bardone, Sergio

    2013-07-01

    Full Text Available The emergence of multicellularity and epithelia in relation to the appearance of cellular junctions, in order to illustrate the first steps of animal evolution, is discussed. We analyzed the structure and roles of adherens and occludins, considered to be the oldest. Also treated are some aspects of the main proteins that constitute them, the cadherins and claudins, as well as the related structures observed in sponges and choanoflagellates, the most ancient animals and the ancestors of these, respectively. It was concluded that the animal ancestor probably possessed some kind of adherens and possibly occludins, appearing as the first of major importance. These junctions increased in complexity through until the complexity observed in modern times.

  14. Analysis of trafficking, stability and function of human connexin 26 gap junction channels with deafness-causing mutations in the fourth transmembrane helix.

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    Cinzia Ambrosi

    Full Text Available Human Connexin26 gene mutations cause hearing loss. These hereditary mutations are the leading cause of childhood deafness worldwide. Mutations in gap junction proteins (connexins can impair intercellular communication by eliminating protein synthesis, mis-trafficking, or inducing channels that fail to dock or have aberrant function. We previously identified a new class of mutants that form non-functional gap junction channels and hemichannels (connexons by disrupting packing and inter-helix interactions. Here we analyzed fourteen point mutations in the fourth transmembrane helix of connexin26 (Cx26 that cause non-syndromic hearing loss. Eight mutations caused mis-trafficking (K188R, F191L, V198M, S199F, G200R, I203K, L205P, T208P. Of the remaining six that formed gap junctions in mammalian cells, M195T and A197S formed stable hemichannels after isolation with a baculovirus/Sf9 protein purification system, while C202F, I203T, L205V and N206S formed hemichannels with varying degrees of instability. The function of all six gap junction-forming mutants was further assessed through measurement of dye coupling in mammalian cells and junctional conductance in paired Xenopus oocytes. Dye coupling between cell pairs was reduced by varying degrees for all six mutants. In homotypic oocyte pairings, only A197S induced measurable conductance. In heterotypic pairings with wild-type Cx26, five of the six mutants formed functional gap junction channels, albeit with reduced efficiency. None of the mutants displayed significant alterations in sensitivity to transjunctional voltage or induced conductive hemichannels in single oocytes. Intra-hemichannel interactions between mutant and wild-type proteins were assessed in rescue experiments using baculovirus expression in Sf9 insect cells. Of the four unstable mutations (C202F, I203T, L205V, N206S only C202F and N206S formed stable hemichannels when co-expressed with wild-type Cx26. Stable M195T hemichannels

  15. Instigation of endothelial Nlrp3 inflammasome by adipokine visfatin promotes inter-endothelial junction disruption: role of HMGB1.

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    Chen, Yang; Pitzer, Ashley L; Li, Xiang; Li, Pin-Lan; Wang, Lei; Zhang, Yang

    2015-12-01

    Recent studies have indicated that the inflammasome plays a critical role in the pathogenesis of vascular diseases. However, the pathological relevance of this inflammasome activation, particularly in vascular cells, remains largely unknown. Here, we investigated the role of endothelial (Nucleotide-binding Oligomerization Domain) NOD-like receptor family pyrin domain containing three (Nlrp3) inflammasomes in modulating inter-endothelial junction proteins, which are associated with endothelial barrier dysfunction, an early onset of obesity-associated endothelial injury. Our findings demonstrate that the activation of Nlrp3 inflammasome by visfatin markedly decreased the expression of inter-endothelial junction proteins including tight junction proteins ZO-1, ZO-2 and occludin, and adherens junction protein VE-cadherin in cultured mouse vascular endothelial (VE) cell monolayers. Such visfatin-induced down-regulation of junction proteins in endothelial cells was attributed to high mobility group box protein 1 (HMGB1) release derived from endothelial inflammasome-dependent caspase-1 activity. Similarly, in the coronary arteries of wild-type mice, high-fat diet (HFD) treatment caused a down-regulation of inter-endothelial junction proteins ZO-1, ZO-2, occludin and VE-cadherin, which was accompanied with enhanced inflammasome activation and HMGB1 expression in the endothelium as well as transmigration of CD43(+) T cells into the coronary arterial wall. In contrast, all these HFD-induced alterations in coronary arteries were prevented in mice with Nlrp3 gene deletion. Taken together, these data strongly suggest that the activation of endothelial Nlrp3 inflammasomes as a result of the increased actions of injurious adipokines such as visfatin produces HMGB1, which act in paracrine or autocrine fashion to disrupt inter-endothelial junctions and increase paracellular permeability of the endothelium contributing to the early onset of endothelial injury during metabolic

  16. Connexin mutation that causes dominant congenital cataracts inhibits gap junctions, but not hemichannels, in a dominant negative manner.

    Science.gov (United States)

    Banks, Eric A; Toloue, Masoud M; Shi, Qian; Zhou, Zifei Jade; Liu, Jialu; Nicholson, Bruce J; Jiang, Jean X

    2009-02-01

    The connexin (Cx) 50, E48K, mutation is associated with a human dominant congenital cataract; however, the underlying molecular mechanism has not been characterized. The glutamate (E) residue at position 48 is highly conserved across animal species and types of connexins. When expressed in paired Xenopus oocytes, human (h) and chicken (ch) Cx50 E48K mutants showed no electrical coupling. In addition, this mutation acts in a dominant negative manner when paired hetero-typically or hetero-merically with wild-type Cx50, but has no such effect on Cx46, the other lens fiber connexin. A similar loss-of-function and dominant negative effect was observed using dye transfer assays in the same system. By using two different dye transfer methods, with two different tracer dyes, we found chCx50 E48K expressed in chicken lens embryonic fibroblast cells by retroviral infection similarly failed to induce dye coupling, and prevented wild-type chCx50 from forming functional gap junctions. In contrast to its effect on gap junctions, the E48K mutation has no effect on hemichannel activity when assayed using electrical conductance in oocytes, and mechanically induced dye uptake in cells. Cx50 is functionally involved in cell differentiation and lens development, and the E48K mutant promotes primary lens cell differentiation indistinguishable from wild-type chCx50, despite its lack of junctional channel function. Together the data show that mutations affecting gap junctions but not hemichannel function of Cx50 can lead to dominant congenital cataracts in humans. This clearly supports the model of intercellular coupling of fiber cells creating a microcirculation of nutrients and metabolites required for lens transparency.

  17. Cataract-causing mutation of human connexin 46 impairs gap junction, but increases hemichannel function and cell death.

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    Qian Ren

    Full Text Available Connexin channels play a critical role in maintaining metabolic homeostasis and transparency of the lens. Mutations in connexin genes are linked to congenital cataracts in humans. The G143R missense mutation on connexin (Cx 46 was recently reported to be associated with congenital Coppock cataracts. Here, we showed that the G143R mutation decreased Cx46 gap junctional coupling in a dominant negative manner; however, it significantly increased gap junctional plaques. The G143R mutant also increased hemichannel activity, inversely correlated with the level of Cx46 protein on the cell surface. The interaction between cytoplasmic loop domain and C-terminus has been shown to be involved in gating of connexin channels. Interestingly, the G143R mutation enhanced the interaction between intracellular loop and Cx46. Furthermore, this mutation decreased cell viability and the resistance of the cells to oxidative stress, primarily due to the increased hemichannel function. Together, these results suggest that mutation of this highly conserved residue on the cytoplasmic loop domain of Cx46 enhances its interaction with the C-terminus, resulting in a reduction of gap junction channel function, but increased hemichannel function. This combination leads to the development of human congenital cataracts.

  18. Characterization of cytoskeletal and junctional proteins expressed by cells cultured from human arachnoid granulation tissue

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    Mehta Bhavya C

    2005-10-01

    Full Text Available Abstract Background The arachnoid granulations (AGs are projections of the arachnoid membrane into the dural venous sinuses. They function, along with the extracranial lymphatics, to circulate the cerebrospinal fluid (CSF to the systemic venous circulation. Disruption of normal CSF dynamics may result in increased intracranial pressures causing many problems including headaches and visual loss, as in idiopathic intracranial hypertension and hydrocephalus. To study the role of AGs in CSF egress, we have grown cells from human AG tissue in vitro and have characterized their expression of those cytoskeletal and junctional proteins that may function in the regulation of CSF outflow. Methods Human AG tissue was obtained at autopsy, and explanted to cell culture dishes coated with fibronectin. Typically, cells migrated from the explanted tissue after 7–10 days in vitro. Second or third passage cells were seeded onto fibronectin-coated coverslips at confluent densities and grown to confluency for 7–10 days. Arachnoidal cells were tested using immunocytochemical methods for the expression of several common cytoskeletal and junctional proteins. Second and third passage cultures were also labeled with the common endothelial markers CD-31 or VE-cadherin (CD144 and their expression was quantified using flow cytometry analysis. Results Confluent cultures of arachnoidal cells expressed the intermediate filament protein vimentin. Cytokeratin intermediate filaments were expressed variably in a subpopulation of cells. The cultures also expressed the junctional proteins connexin43, desmoplakin 1 and 2, E-cadherin, and zonula occludens-1. Flow cytometry analysis indicated that second and third passage cultures failed to express the endothelial cell markers CD31 or VE-cadherin in significant quantities, thereby showing that these cultures did not consist of endothelial cells from the venous sinus wall. Conclusion To our knowledge, this is the first report of

  19. Synovial cysts of the cervicothoracic junction causing myelopathy: report of 3 cases and review of the literature.

    Science.gov (United States)

    Bisson, Erica F; Sauri-Barraza, José-Carlos; Niazi, Toba; Schmidt, Meic H

    2013-07-01

    Synovial cysts are uncommon pathological entities in patients with cervical degenerative spinal disease, and there are only a few reports in the literature. Treatment typically involves decompression; however, biomechanical data indicate that laminectomies in the cervical spine also result in cervical instability, specifically within the cervicothoracic junction, supporting the use of fusion as well. The authors describe the use of fusion with decompression in the treatment of 3 patients with cervicothoracic synovial cysts that presented in an acute fashion with associated myelopathy and neurological decline, and they review the diagnostic elements, histopathology, and treatment of these cysts. All 3 of the patients did well with decompression via a posterior approach with a single-level instrumented fusion from C-7 to T-1. Each patient regained complete neurological function and had no residual neurological deficits. These results are promising, although the sample size of 3 cases is too small to make any conclusive evaluations. Future studies incorporating Class I and Class II data are imperative to make firm conclusions regarding general management of this rare entity.

  20. Endocytosis and Recycling of Tight Junction Proteins in Inflammation

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    Markus Utech

    2010-01-01

    Full Text Available A critical function of the epithelial lining is to form a barrier that separates luminal contents from the underlying interstitium. This barrier function is primarily regulated by the apical junctional complex (AJC consisting of tight junctions (TJs and adherens junctions (AJs and is compromised under inflammatory conditions. In intestinal epithelial cells, proinflammatory cytokines, for example, interferon-gamma (IFN-γ, induce internalization of TJ proteins by endocytosis. Endocytosed TJ proteins are passed into early and recycling endosomes, suggesting the involvement of recycling of internalized TJ proteins. This review summarizes mechanisms by which TJ proteins under inflammatory conditions are internalized in intestinal epithelial cells and point out comparable mechanism in nonintestinal epithelial cells.

  1. Deficiency of angulin-2/ILDR1, a tricellular tight junction-associated membrane protein, causes deafness with cochlear hair cell degeneration in mice.

    Science.gov (United States)

    Higashi, Tomohito; Katsuno, Tatsuya; Kitajiri, Shin-Ichiro; Furuse, Mikio

    2015-01-01

    Tricellular tight junctions seal the extracellular spaces of tricellular contacts, where the vertices of three epithelial cells meet, and are required for the establishment of a strong barrier function of the epithelial cellular sheet. Angulins and tricellulin are known as specific protein components of tricellular tight junctions, where angulins recruit tricellulin. Mutations in the genes encoding angulin-2/ILDR1 and tricellulin have been reported to cause human hereditary deafness DFNB42 and DFNB49, respectively. To investigate the pathogenesis of DFNB42, we analyzed mice with a targeted disruption of Ildr1, which encodes angulin-2/ILDR1. Ildr1 null mice exhibited profound deafness. Hair cells in the cochlea of Ildr1 null mice develop normally, but begin to degenerate by two weeks after birth. Tricellulin localization at tricellular contacts of the organ of Corti in the cochlea was retained in Ildr1 null mice, but its distribution along the depth of tricellular contacts was affected. Interestingly, compensatory tricellular contact localization of angulin-1/LSR was observed in the organ of Corti in Ildr1 null mice although it was hardly detected in the organ of Corti in wild-type mice. The onset of hair cell degeneration in Ildr1 null mice was earlier than that in the reported Tric mutant mice, which mimic one of the tricellulin mutations in DFNB49 deafness. These results indicate that the angulin-2/ILDR1 deficiency causes the postnatal degenerative loss of hair cells in the cochlea, leading to human deafness DFNB42. Our data also suggest that angulin family proteins have distinct functions in addition to their common roles of tricellulin recruitment and that the function of angulin-2/ILDR1 for hearing cannot be substituted by angulin-1/LSR.

  2. A MusD retrotransposon insertion in the mouse Slc6a5 gene causes alterations in neuromuscular junction maturation and behavioral phenotypes.

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    Laurent P Bogdanik

    Full Text Available Glycine is the major inhibitory neurotransmitter in the spinal cord and some brain regions. The presynaptic glycine transporter, GlyT2, is required for sustained glycinergic transmission through presynaptic reuptake and recycling of glycine. Mutations in SLC6A5, encoding GlyT2, cause hereditary hyperekplexia in humans, and similar phenotypes in knock-out mice, and variants are associated with schizophrenia. We identified a spontaneous mutation in mouse Slc6a5, caused by a MusD retrotransposon insertion. The GlyT2 protein is undetectable in homozygous mutants, indicating a null allele. Homozygous mutant mice are normal at birth, but develop handling-induced spasms at five days of age, and only survive for two weeks, but allow the study of early activity-regulated developmental processes. At the neuromuscular junction, synapse elimination and the switch from embryonic to adult acetylcholine receptor subunits are hastened, consistent with a presumed increase in motor neuron activity, and transcription of acetylcholine receptors is elevated. Heterozygous mice, which show no reduction in lifespan but nonetheless have reduced levels of GlyT2, have a normal thermal sensitivity with the hot-plate test, but differences in repetitive grooming and decreased sleep time with home-cage monitoring. Open-field and elevated plus-maze tests did not detect anxiety-like behaviors; however, the latter showed a hyperactivity phenotype. Importantly, grooming and hyperactivity are observed in mouse schizophrenia models. Thus, mutations in Slc6a5 show changes in neuromuscular junction development as homozygotes, and behavioral phenotypes as heterozygotes, indicating their usefulness for studies related to glycinergic dysfunction.

  3. An unusual cause of chronic abdominal pain after laparoscopic Roux en Y gastric bypass: Case report of a penetrating fish bone causing adhesions at the biliary-digestive junction resulting in partial obstruction and chronic symptoms

    Science.gov (United States)

    Ochieng, Vincent; Hendrickx, Leo; Valk, Jody

    2016-01-01

    Background The management of chronic abdominal pain after laparoscopic Roux-en-Y gastric bypass (LRYGP) is complex and challenging. Foreign body intestinal perforation including that caused by fish bones has previously been reported in the literature and if clinically unrecognized, can cause significant morbidity and mortality. Fish bone perforation as a cause of chronic abdominal pain after LRYGP has rarely been reported. Summary The unusual case of a 54 year old female presenting with recurrent episodes of postprandial pain 2 years after LRYGP is reported. Previous radiological and endoscopic investigations did not reveal any abnormality and after the most recent clinical presentation, a laparoscopic exploration was performed. A protruding fish bone at the biliary-digestive junction was discovered intra-operatively and successfully extracted. Dense adhesions between the involved intestinal loops were lysed in an attempt to improve intestinal transit and subsequently relieve post-prandial pain. Conclusion This case highlights the possibility of a missed fish bone perforation causing chronic postprandial abdominal pain and discomfort in a patient with a Roux-en-Y gastric bypass anatomy. Foreign body perforation is a rare cause of abdominal pain after gastric bypass that should be considered when evaluating chronic abdominal pain symptoms after LRYGP. PMID:27107305

  4. Gap Junctions

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    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  5. Gap junctions.

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2012-07-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1853-1872, 2012.

  6. Tight junction disruption induced by type 3 secretion system effectors injected by Enteropathogenic and Enterohemorrhagic Escherichia coli

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    Paul Ugalde-Silva

    2016-08-01

    Full Text Available The intestinal epithelium consists of a single cell layer, which is a critical selectively permeable barrier to both absorb nutrients and avoid the entry of potentially harmful entities, including microorganisms. Epithelial cells are held together by the apical junctional complexes, consisting of adherens junctions and tight junctions (TJs, and by underlying desmosomes. TJs lay in the apical domain of epithelial cells and are mainly composed by transmembrane proteins such as occludin, claudins, JAMs, and tricellulin, that are associated with the cytoplasmic plaque formed by proteins from the MAGUK family, such as ZO-1/2/3, connecting TJ to the actin cytoskeleton, and cingulin and paracingulin connecting TJ to the microtubule network. Extracellular bacteria such as EPEC and EHEC living in the intestinal lumen inject effectors proteins directly from the bacterial cytoplasm to the host cell cytoplasm, where they play a relevant role in the manipulation of the eukaryotic cell functions by modifying or blocking cell signaling pathways. TJ integrity depends on various cell functions such as actin cytoskeleton, microtubule network for vesicular trafficking, membrane integrity, inflammation, and cell survival. EPEC and EHEC effectors target most of these functions. Effectors encoded inside or outside of locus of enterocyte effacement (LEE disrupt the TJ strands. EPEC and EHEC exploit the TJ dynamics to open this structure, for causing diarrhea. EPEC and EHEC secrete effectors that mimic host proteins to manipulate the signaling pathways, including those related to TJ dynamics. In this review, we focus on the known mechanisms exploited by EPEC and EHEC effectors for causing TJ disruption.

  7. Loss of αT-catenin alters the hybrid adhering junctions in the heart and leads to dilated cardiomyopathy and ventricular arrhythmia following acute ischemia.

    Science.gov (United States)

    Li, Jifen; Goossens, Steven; van Hengel, Jolanda; Gao, Erhe; Cheng, Lan; Tyberghein, Koen; Shang, Xiying; De Rycke, Riet; van Roy, Frans; Radice, Glenn L

    2012-02-15

    It is generally accepted that the intercalated disc (ICD) required for mechano-electrical coupling in the heart consists of three distinct junctional complexes: adherens junctions, desmosomes and gap junctions. However, recent morphological and molecular data indicate a mixing of adherens junctional and desmosomal components, resulting in a 'hybrid adhering junction' or 'area composita'. The α-catenin family member αT-catenin, part of the N-cadherin-catenin adhesion complex in the heart, is the only α-catenin that interacts with the desmosomal protein plakophilin-2 (PKP2). Thus, it has been postulated that αT-catenin might serve as a molecular integrator of the two adhesion complexes in the area composita. To investigate the role of αT-catenin in the heart, gene targeting technology was used to delete the Ctnna3 gene, encoding αT-catenin, in the mouse. The αT-catenin-null mice are viable and fertile; however, the animals exhibit progressive cardiomyopathy. Adherens junctional and desmosomal proteins were unaffected by loss of αT-catenin, with the exception of the desmosomal protein PKP2. Immunogold labeling at the ICD demonstrated in the αT-catenin-null heart a preferential reduction of PKP2 at the area composita compared with the desmosome. Furthermore, gap junction protein Cx43 was reduced at the ICD, including its colocalization with N-cadherin. Gap junction remodeling in αT-catenin-knockout hearts was associated with an increased incidence of ventricular arrhythmias after acute ischemia. This novel animal model demonstrates for the first time how perturbation in αT-catenin can affect both PKP2 and Cx43 and thereby highlights the importance of understanding the crosstalk between the junctional proteins of the ICD and its implications for arrhythmogenic cardiomyopathy.

  8. ROCK activity regulates functional tight junction assembly during blastocyst formation in porcine parthenogenetic embryos

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    Jeongwoo Kwon

    2016-04-01

    Full Text Available The Rho-associated coiled-coil-containing protein serine/threonine kinases 1 and 2 (ROCK1 and ROCK2 are Rho subfamily GTPase downstream effectors that regulate cell migration, intercellular adhesion, cell polarity, and cell proliferation by stimulating actin cytoskeleton reorganization. Inhibition of ROCK proteins affects specification of the trophectoderm (TE and inner cell mass (ICM lineages, compaction, and blastocyst cavitation. However, the molecules involved in blastocyst formation are not known. Here, we examined developmental competence and levels of adherens/tight junction (AJ/TJ constituent proteins, such as CXADR, OCLN, TJP1, and CDH1, as well as expression of their respective mRNAs, after treating porcine parthenogenetic four-cell embryos with Y-27632, a specific inhibitor of ROCK, at concentrations of 0, 10, 20, 100 µM for 24 h. Following this treatment, the blastocyst development rates were 39.1, 20.7, 10.0, and 0% respectively. In embryos treated with 20 µM treatment, expression levels of CXADR, OCLN, TJP1, and CDH1 mRNA and protein molecules were significantly reduced (P < 0.05. FITC-dextran uptake assay revealed that the treatment caused an increase in TE TJ permeability. Interestingly, the majority of the four-cell and morula embryos treated with 20 µM Y-27643 for 24 h showed defective compaction and cavitation. Taken together, our results indicate that ROCK activity may differentially affect assembly of AJ/TJs as well as regulate expression of genes encoding junctional proteins.

  9. armadillo, bazooka, and stardust are critical for early stages in formation of the zonula adherens and maintenance of the polarized blastoderm epithelium in Drosophila.

    Science.gov (United States)

    Müller, H A; Wieschaus, E

    1996-07-01

    Cellularization of the Drosophila embryo results in the formation of a cell monolayer with many characteristics of a polarized epithelium. We have used antibodies specific to cellular junctions and nascent plasma membranes to study the formation of the zonula adherens (ZA) in relation to the establishment of basolateral membrane polarity. The same approach was then used as a test system to identify X-linked zygotically active genes required for ZA formation. We show that ZA formation begins during cellularization and that the basolateral membrane domain is established at mid-gastrulation. By creating deficiencies for defined regions of the X chromosome, we have identified genes that are required for the formation of the ZA and the generation of basolateral membrane polarity. We show that embryos mutant for both stardust (sdt) and bazooka (baz) fail to form a ZA. In addition to the failure to establish the ZA, the formation of the monolayered epithelium is disrupted after cellularization, resulting in formation of a multilayered cell sheet by mid-gastrulation. SEM analysis of mutant embryos revealed a conversion of cells exhibiting epithelial characteristics into cells exhibiting mesenchymal characteristics. To investigate how mutations that affect an integral component of the ZA itself influence ZA formation, we examined embryos with reduced maternal and zygotic supply of wild-type Arm protein. These embryos, like embryos mutant for both sdt and baz, exhibit an early disruption of ZA formation. These results suggest that early stages in the assembly of the ZA are critical for the stability of the polarized blastoderm epithelium.

  10. Testicular cell junction: a novel target for male contraception.

    Science.gov (United States)

    Lee, Nikki P Y; Wong, Elissa W P; Mruk, Dolores D; Cheng, C Yan

    2009-01-01

    Even though various contraceptive methods are widely available, the number of unwanted pregnancies is still on the rise in developing countries, pressurizing the already resource limited nations. One of the major underlying reasons is the lack of effective, low cost, and safe contraceptives for couples. During the past decade, some studies were performed using animal models to decipher if the Sertoli-germ cell junction in the testis is a target for male fertility regulation. Some of these study models were based on the use of hormones and/or chemicals to disrupt the hypothalamic-pituitary-testicular axis (e.g., androgen-based implants or pills) and others utilized a panel of chemical entities or synthetic peptides to perturb spermatogenesis either reversibly or non-reversibly. Among them, adjudin, a potential male contraceptive, is one of the compounds exerting its action on the unique adherens junctions, known as ectoplasmic specializations, in the testis. Since the testis is equipped with inter-connected cell junctions, an initial targeting of one junction type may affect the others and these accumulative effects could lead to spermatogenic arrest. This review attempts to cover an innovative theme on how male infertility can be achieved by inducing junction instability and defects in the testis, opening a new window of research for male contraceptive development. While it will still take much time and effort of intensive investigation before a product can reach the consumable market, these findings have provided hope for better family planning involving men.

  11. Virus interaction with the apical junctional complex.

    Science.gov (United States)

    Gonzalez-Mariscal, Lorenza; Garay, Erika; Lechuga, Susana

    2009-01-01

    In order to infect pathogens must breach the epithelial barriers that separate the organism from the external environment or that cover the internal cavities and ducts of the body. Epithelia seal the passage through the paracellular pathway with the apical junctional complex integrated by tight and adherens junctions. In this review we describe how viruses like coxsackie, swine vesicular disease virus, adenovirus, reovirus, feline calcivirus, herpes viruses 1 and 2, pseudorabies, bovine herpes virus 1, poliovirus and hepatitis C use as cellular receptors integral proteins present at the AJC of epithelial cells. Interaction with these proteins contributes in a significant manner in defining the particular tropism of each virus. Besides these proteins, viruses exhibit a wide range of cellular co-receptors among which proteins present in the basolateral cell surface like integrins are often found. Therefore targeting proteins of the AJC constitutes a strategy that might allow viruses to bypass the physical barrier that blocks their access to receptors expressed on the basolateral surface of epithelial cells.

  12. Direct Exposure to Ethanol Disrupts Junctional Cell-Cell Contact and Hippo-YAP Signaling in HL-1 Murine Atrial Cardiomyocytes.

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    Kanako Noritake

    Full Text Available Direct exposure of cardiomyocytes to ethanol causes cardiac damage such as cardiac arrythmias and apoptotic cell death. Cardiomyocytes are connected to each other through intercalated disks (ID, which are composed of a gap junction (GJ, adherens junction, and desmosome. Changes in the content as well as the subcellular localization of connexin43 (Cx43, the main component of the cardiac GJ, are reportedly involved in cardiac arrythmias and subsequent damage. Recently, the hippo-YAP signaling pathway, which links cellular physical status to cell proliferation, differentiation, and apoptosis, has been implicated in cardiac homeostasis under physiological as well as pathological conditions. This study was conducted to explore the possible involvement of junctional intercellular communication, mechanotransduction through cytoskeletal organization, and the hippo-YAP pathway in cardiac damage caused by direct exposure to ethanol. HL-1 murine atrial cardiac cells were used since these cells retain cardiac phenotypes through ID formation and subsequent synchronous contraction. Cells were exposed to 0.5-2% ethanol; significant apoptotic cell death was observed after exposure to 2% ethanol for 48 hours. A decrease in Cx43 levels was already observed after 3 hours exposure to 2% ethanol, suggesting a rapid degradation of this protein. Upon exposure to ethanol, Cx43 translocated into lysosomes. Cellular cytoskeletal organization was also dysregulated by ethanol, as demonstrated by the disruption of myofibrils and intermediate filaments. Coinciding with the loss of cell-cell adherence, decreased phosphorylation of YAP, a hippo pathway effector, was also observed in ethanol-treated cells. Taken together, the results provide evidence that cells exposed directly to ethanol show 1 impaired cell-cell adherence/communication, 2 decreased cellular mechanotransduction by the cytoskeleton, and 3 a suppressed hippo-YAP pathway. Suppression of hippo-YAP pathway

  13. Selective permeability of gap junction channels.

    Science.gov (United States)

    Goldberg, Gary S; Valiunas, Virginijus; Brink, Peter R

    2004-03-23

    Gap junctions mediate the transfer of small cytoplasmic molecules between adjacent cells. A family of gap junction proteins exist that form channels with unique properties, and differ in their ability to mediate the transfer of specific molecules. Mutations in a number of individual gap junction proteins, called connexins, cause specific human diseases. Therefore, it is important to understand how gap junctions selectively move molecules between cells. Rules that dictate the ability of a molecule to travel through gap junction channels are complex. In addition to molecular weight and size, the ability of a solute to transverse these channels depends on its net charge, shape, and interactions with specific connexins that constitute gap junctions in particular cells. This review presents some data and interpretations pertaining to mechanisms that govern the differential transfer of signals through gap junction channels.

  14. Imaging of cervicothoracic junction trauma

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    Wongwaisayawan S

    2013-01-01

    Full Text Available Sirote Wongwaisayawan,1 Ruedeekorn Suwannanon,2 Rathachai Kaewlai11Department of Radiology, Ramathibodi Hospital and Mahidol University, Bangkok, Thailand; 2Department of Radiology, Faculty of Medicine, Prince of Songkla University, Hat Yai, ThailandAbstract: Cervicothoracic junction trauma is an important cause of morbidity and mortality in trauma patients. Imaging has played an important role in identifying injuries and guiding appropriate, timely therapy. Computed tomography is currently a method of choice for diagnosing cervicothoracic junction trauma, in which the pattern of injuries often suggests possible mechanisms and potential injuries. In this article, the authors describe and illustrate common and uncommon injuries that can occur in the cervicothoracic junction.Keywords: cervicothoracic junction, cervical spine, trauma, imaging, radiology

  15. Ectopic overexpression of engrailed-2 in cerebellar Purkinje cells causes restricted cell loss and retarded external germinal layer development at lobule junctions.

    Science.gov (United States)

    Baader, S L; Sanlioglu, S; Berrebi, A S; Parker-Thornburg, J; Oberdick, J

    1998-03-01

    Members of the En and Wnt gene families seem to play a key role in the early specification of the brain territory that gives rise to the cerebellum, the midhindbrain junction. To analyze the possible continuous role of the En and Wnt signaling pathway in later cerebellar patterning and function, we expressed En-2 ectopically in Purkinje cells during late embryonic and postnatal cerebellar development. As a result of this expression, the cerebellum is greatly reduced in size, and Purkinje cell numbers throughout the cerebellum are reduced by more than one-third relative to normal animals. Detailed analysis of both adult and developing cerebella reveals a pattern of selectivity to the loss of Purkinje cells and other cerebellar neurons. This is observed as a general loss of prominence of cerebellar fissures that is highlighted by a total loss of sublobular fissures. In contrast, mediolateral patterning is generally only subtly affected. That En-2 overexpression selectively affects Purkinje cells in the transition zone between lobules is evidenced by direct observation of selective Purkinje cell loss in certain fissures and by the observation that growth and migration of the external germinal layer (EGL) is selectively retarded in the deep fissures during early postnatal development. Thus, in addition to demonstrating the critical role of Purkinje cells in the generation and migration of granule cells, the heterogeneous distribution of cellular effects induced by ectopic En expression suggests a relatively late morphogenetic role for this and other segment polarity proteins, mainly oriented at lobule junctions.

  16. Injection of a soluble fragment of neural agrin (NT-1654 considerably improves the muscle pathology caused by the disassembly of the neuromuscular junction.

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    Stefan Hettwer

    Full Text Available Treatment of neuromuscular diseases is still an unsolved problem. Evidence over the last years strongly indicates the involvement of malformation and dysfunction of neuromuscular junctions in the development of such medical conditions. Stabilization of NMJs thus seems to be a promising approach to attenuate the disease progression of muscle wasting diseases. An important pathway for the formation and maintenance of NMJs is the agrin/Lrp4/MuSK pathway. Here we demonstrate that the agrin biologic NT-1654 is capable of activating the agrin/Lrp4/MuSK system in vivo, leading to an almost full reversal of the sarcopenia-like phenotype in neurotrypsin-overexpressing (SARCO mice. We also show that injection of NT-1654 accelerates muscle re-innervation after nerve crush. This report demonstrates that a systemically administered agrin fragment has the potential to counteract the symptoms of neuromuscular disorders.

  17. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-09-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  18. Actin-interacting protein 1 controls assembly and permeability of intestinal epithelial apical junctions.

    Science.gov (United States)

    Lechuga, Susana; Baranwal, Somesh; Ivanov, Andrei I

    2015-05-01

    Adherens junctions (AJs) and tight junctions (TJs) are crucial regulators of the integrity and restitution of the intestinal epithelial barrier. The structure and function of epithelial junctions depend on their association with the cortical actin cytoskeleton that, in polarized epithelial cells, is represented by a prominent perijunctional actomyosin belt. The assembly and stability of the perijunctional cytoskeleton is controlled by constant turnover (disassembly and reassembly) of actin filaments. Actin-interacting protein (Aip) 1 is an emerging regulator of the actin cytoskeleton, playing a critical role in filament disassembly. In this study, we examined the roles of Aip1 in regulating the structure and remodeling of AJs and TJs in human intestinal epithelium. Aip1 was enriched at apical junctions in polarized human intestinal epithelial cells and normal mouse colonic mucosa. Knockdown of Aip1 by RNA interference increased the paracellular permeability of epithelial cell monolayers, decreased recruitment of AJ/TJ proteins to steady-state intercellular contacts, and attenuated junctional reassembly in a calcium-switch model. The observed defects of AJ/TJ structure and functions were accompanied by abnormal organization and dynamics of the perijunctional F-actin cytoskeleton. Moreover, loss of Aip1 impaired the apico-basal polarity of intestinal epithelial cell monolayers and inhibited formation of polarized epithelial cysts in 3-D Matrigel. Our findings demonstrate a previously unanticipated role of Aip1 in regulating the structure and remodeling of intestinal epithelial junctions and early steps of epithelial morphogenesis.

  19. Point correlation dimension can reveal functional changes caused by gap junction blockers in the 4-aminopyridine in vivo rat epilepsy model

    Energy Technology Data Exchange (ETDEWEB)

    Jardanhazy, Anett [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary); Molnar, Mark [Department of Psychophysiology, Institute for Psychology of the Hungarian Academy of Sciences, P.O. Box 398, Budapest H-1394 (Hungary)], E-mail: molnar@cogpsyphy.hu; Jardanhazy, Tamas [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary)], E-mail: jt@nepsy.szote.u-szeged.hu

    2009-04-15

    The contribution of gap junction (GJ) blockers to seizure initiation was reexamined by means of an analysis on nonlinear dynamics with point correlation dimension (PD2i) at as well as around the primary focus, and mirror focus in an already active 4-aminopyridine-induced in vivo epilepsy model. From the data base of the ECoGs of anesthetized adult rats treated with quinine, a selective blocker of Cx36, and in combination with an additional broad-spectrum GJ blocker, carbenoxolone, 14 cases of each condition were reexamined with a stationarity insensitive nonlinear PD2i method. The blockade of the Cx36 channels decreased the usual drop of the point correlation dimension at the beginning of the seizures, and this was enhanced by the additional use of the global blocker carbenoxolone. The so-called characteristic DC shift just prior to seizure onset denotes a low dimensional seizure event and the recognizable seizures display very variable, rapidly changing dynamics, as revealed by the PD2i analysis. This nonlinear PD2i analysis demonstrated that the different GJ blockers in the already active epileptic model helped seizure initiation, but exerted inhibitory effects on the seizure onset itself, acting differently on the local components of the network organization generating seizure discharges, possibly changing the coupling strengths and time delays in the GJ-s.

  20. How useful is esophageal high resolution manometry in diagnosing gastroesophageal junction disruption: causes affecting this disruption and its relationship with manometric alterations and gastroesophageal reflux

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    Constanza Ciriza-de-los-Ríos

    2014-01-01

    Full Text Available Background: High-resolution manometry (HRM is a breakthrough in the morphological study of the gastroesophageal junction (GEJ and its degrees of disruption. Objectives: a Assessment of risk factors involved in the disruption of the GEJ in patients with gastroesophageal reflux (GER symptoms; b the relationship between the type of GEJ and GER demonstrated by 24 hours pH-monitoring; and c identification of the alterations in the manometric parameters related to the morphology of the GEJ. Methods: One hundred and fifteen patients with symptoms of GER studied with HRM and classified by the type of GEJ (type I: Normal; type II: Sliding; type III: Hiatal hernia. Twenty four hour pH-monitoring without proton pump inhibitors was performed in all of them. Epidemiological aspects, manometric parameters (Chicago 2012 classification and the pH-monitoring results were evaluated. Results: Age (OR 1.033 [1.006-1.060]; p = 0.16, BMI (OR 1.097 [1.022-1.176]; p = 0. 01 and abdominal perimeter (OR 1.034 [1.005-1.063]; p = 0.0215 were independent risk factors for the GEJ type III (area under the curve 0.70. Disruption of the GEJ was associated with a lower resting pressure (p = 0.006, greater length (p < 0.001 and greater esophageal shortening (p < 0.001. Abnormal acidic reflux was found in the total period (p = 0.015, standing (p = 0.022 and supine (p = 0.001 in patients with GEJ type II and III with respect to type I. Conclusions: Increased age, overweight and central obesity pose a higher risk of GEJ type III (hiatal hernia. The greater disruption of the GEJ is associated with lower resting pressure, esophageal shortening, and higher acid exposure in the pH-monitoring.

  1. Expression of TM4SF10, a Claudin/EMP/PMP22 family cell junction protein, during mouse kidney development and podocyte differentiation.

    Science.gov (United States)

    Bruggeman, Leslie A; Martinka, Scott; Simske, Jeffrey S

    2007-02-01

    Cell junctions in the nephron are highly specialized to perform specific and distinct filtration and reabsorption functions. The mature kidney forms complex cell junctions including slit diaphragms that prevent the passage of serum proteins into the filtrate, and tubule cell junctions that regulate specific paracellular ion reuptake. We have investigated the expression of TM4SF10 (Trans-Membrane tetra(4)-Span Family 10) in mouse kidneys. TM4SF10 is the vertebrate orthologue of Caenorhabditis elegans VAB-9, a tetraspan adherens junction protein in the PMP22/EMP/Claudin family of proteins. We found that TM4SF10 localizes at the basal-most region of podocyte precursors before the capillary loop stage, at some tubule precursors, and at the ureteric bud junction with S-shaped bodies. Overall expression of TM4SF10 peaked at postnatal day 4 and was virtually absent in adult kidneys. The very limited expression of TM4SF10 protein that persisted into adulthood was restricted to a few tubule segments but remained localized to the basal region of lateral membranes. In undifferentiated cultured podocytes, TM4SF10 localized to the perinuclear region and translocated to the cell membrane after Cadherin appearance at cell-cell contacts. TM4SF10 colocalized with ZO1 and p120ctn in undifferentiated confluent podocytes and also colocalized with the tips of actin filaments at cell contacts. Upon differentiation of cultured podocytes, TM4SF10 protein disappeared from cell contacts and expression ceased. These results suggest that TM4SF10 functions during differentiation of podocytes and may participate in the maturation of cell junctions from simple adherens junctions to elaborate slit diaphragms. TM4SF10 may define a new class of Claudin-like proteins that function during junctional development.

  2. Expression of Tight Junction Proteins and Cadherin 17 in the Small Intestine of Young Goats Offered a Reduced N and/or Ca Diet

    Science.gov (United States)

    Wilkens, Mirja R.; Breves, Gerhard; Langeheine, Marion; Brehm, Ralph; Muscher-Banse, Alexandra S.

    2016-01-01

    Diets fed to ruminants should contain nitrogen (N) as low as possible to reduce feed costs and environmental pollution. Though possessing effective N-recycling mechanisms to maintain the N supply for rumen microbial protein synthesis and hence protein supply for the host, an N reduction caused substantial changes in calcium (Ca) and phosphate homeostasis in young goats including decreased intestinal transepithelial Ca absorption as reported for monogastric species. In contrast to the transcellular component of transepithelial Ca transport, the paracellular route has not been investigated in young goats. Therefore, the aim of the present study was to characterise the effects of dietary N and/or Ca reduction on paracellular transport mechanisms in young goats. Electrophysiological properties of intestinal epithelia were investigated by Ussing chamber experiments. The expression of tight junction (TJ) and adherens junction (AJ) proteins in intestinal epithelia were examined on mRNA level by qPCR and on protein level by western blot analysis. Dietary N reduction led to a segment specific increase in tissue conductances in the proximal jejunum which might be linked to concomitantly decreased expression of cadherin 17 mRNA. Expression of occludin (OCLN) and zonula occludens protein 1 was increased in mid jejunal epithelia of N reduced fed goats on mRNA and partly on protein level. Reduced dietary Ca supply resulted in a segment specific increase in claudin 2 and claudin 12 expression and decreased the expression of OCLN which might have been mediated at least in part by calcitriol. These data show that dietary N as well as Ca reduction affected expression of TJ and AJ proteins in a segment specific manner in young goats and may thus be involved in modulation of paracellular Ca permeability. PMID:27120348

  3. Expression of Tight Junction Proteins and Cadherin 17 in the Small Intestine of Young Goats Offered a Reduced N and/or Ca Diet.

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    Kristin Elfers

    Full Text Available Diets fed to ruminants should contain nitrogen (N as low as possible to reduce feed costs and environmental pollution. Though possessing effective N-recycling mechanisms to maintain the N supply for rumen microbial protein synthesis and hence protein supply for the host, an N reduction caused substantial changes in calcium (Ca and phosphate homeostasis in young goats including decreased intestinal transepithelial Ca absorption as reported for monogastric species. In contrast to the transcellular component of transepithelial Ca transport, the paracellular route has not been investigated in young goats. Therefore, the aim of the present study was to characterise the effects of dietary N and/or Ca reduction on paracellular transport mechanisms in young goats. Electrophysiological properties of intestinal epithelia were investigated by Ussing chamber experiments. The expression of tight junction (TJ and adherens junction (AJ proteins in intestinal epithelia were examined on mRNA level by qPCR and on protein level by western blot analysis. Dietary N reduction led to a segment specific increase in tissue conductances in the proximal jejunum which might be linked to concomitantly decreased expression of cadherin 17 mRNA. Expression of occludin (OCLN and zonula occludens protein 1 was increased in mid jejunal epithelia of N reduced fed goats on mRNA and partly on protein level. Reduced dietary Ca supply resulted in a segment specific increase in claudin 2 and claudin 12 expression and decreased the expression of OCLN which might have been mediated at least in part by calcitriol. These data show that dietary N as well as Ca reduction affected expression of TJ and AJ proteins in a segment specific manner in young goats and may thus be involved in modulation of paracellular Ca permeability.

  4. Desmosomal Molecules In and Out of Adhering Junctions: Normal and Diseased States of Epidermal, Cardiac and Mesenchymally Derived Cells

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    Sebastian Pieperhoff

    2010-01-01

    Full Text Available Current cell biology textbooks mention only two kinds of cell-to-cell adhering junctions coated with the cytoplasmic plaques: the desmosomes (maculae adhaerentes, anchoring intermediate-sized filaments (IFs, and the actin microfilament-anchoring adherens junctions (AJs, including both punctate (puncta adhaerentia and elongate (fasciae adhaerentes structures. In addition, however, a series of other junction types has been identified and characterized which contain desmosomal molecules but do not fit the definition of desmosomes. Of these special cell-cell junctions containing desmosomal glycoproteins or proteins we review the composite junctions (areae compositae connecting the cardiomyocytes of mature mammalian hearts and their importance in relation to human arrhythmogenic cardiomyopathies. We also emphasize the various plakophilin-2-positive plaques in AJs (coniunctiones adhaerentes connecting proliferatively active mesenchymally-derived cells, including interstitial cells of the heart and several soft tissue tumor cell types. Moreover, desmoplakin has also been recognized as a constituent of the plaques of the complexus adhaerentes connecting certain lymphatic endothelial cells. Finally, we emphasize the occurrence of the desmosomal transmembrane glycoprotein, desmoglein Dsg2, out of the context of any junction as dispersed cell surface molecules in certain types of melanoma cells and melanocytes. This broadening of our knowledge on the diversity of AJ structures indicates that it may still be too premature to close the textbook chapters on cell-cell junctions.

  5. Molecular electronic junction transport

    DEFF Research Database (Denmark)

    Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

    2012-01-01

    Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and f...

  6. Cell culture model predicts human disease: Altered expression of junction proteins and matrix metalloproteinases in cervical dysplasia

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    Kivi Niina

    2012-08-01

    Full Text Available Abstract Background Cervical cancer is necessarily caused by human papillomaviruses, which encode three oncogenes manifesting their functions by interfering with a number of cellular proteins and pathways: the E5, E6, and E7 proteins. We have earlier found in our microarray studies that the E5 oncogene crucially affects the expression of cellular genes involved in adhesion and motility of epithelial cells. Methods In order to biologically validate our previous experimental findings we performed immunohistochemical staining of a representative set of tissue samples from different grades of high-risk human papillomavirus associated cervical disease as well as normal squamous and columnar cervical epithelium. Three-dimensional collagen raft cultures established from E5-expressing and control epithelial cells were also examined. The expression of p16, matrix metalloproteinase (MMP -7, MMP-16, cytokeratin (CK 8/18, laminin, E-cadherin and beta-catenin was studied. Results In agreement with our previous microarray studies, we found intense staining for E-cadherin and beta-catenin in adherens junctions even in high-grade cervical lesions. Staining for MMP-16 was increased in severe disease as well. No significant change in staining for MMP-7 and cytokeratin 8/18 along with the grade of cervical squamous epithelial disease was observed. Conclusions Here we have confirmed, using tissue material from human papillomavirus associated lesions, some of the cellular gene expression modifications that we earlier reported in an experimental system studying specifically the E5 oncogene of papillomaviruses. These findings were partially surprising in the context of cervical carcinogenesis and emphasize that the complexity of carcinogenesis is not yet fully understood. Microarray approaches provide a wide overwiev of gene expression in experimental settings, which may yield biologically valid biomarkers for disease diagnostics, prognosis, and follow-up.

  7. An unusual cause of chronic abdominal pain after laparoscopic Roux en Y gastric bypass: Case report of a penetrating fish bone causing adhesions at the biliary-digestive junction resulting in partial obstruction and chronic symptoms

    Directory of Open Access Journals (Sweden)

    Vincent Ochieng

    2016-01-01

    Conclusion: This case highlights the possibility of a missed fish bone perforation causing chronic postprandial abdominal pain and discomfort in a patient with a Roux-en-Y gastric bypass anatomy. Foreign body perforation is a rare cause of abdominal pain after gastric bypass that should be considered when evaluating chronic abdominal pain symptoms after LRYGP.

  8. Lipopolysaccharide Causes an Increase in Intestinal Tight Junction Permeability in Vitro and in Vivo by Inducing Enterocyte Membrane Expression and Localization of TLR-4 and CD14

    Science.gov (United States)

    Guo, Shuhong; Al-Sadi, Rana; Said, Hamid M.; Ma, Thomas Y.

    2014-01-01

    Bacterial-derived lipopolysaccharides (LPS) play an essential role in the inflammatory process of inflammatory bowel disease. A defective intestinal tight junction (TJ) barrier is an important pathogenic factor of inflammatory bowel disease and other inflammatory conditions of the gut. Despite its importance in mediating intestinal inflammation, the physiological effects of LPS on the intestinal epithelial barrier remain unclear. The major aims of this study were to determine the effects of physiologically relevant concentrations of LPS (0 to 1 ng/mL) on intestinal barrier function using an in vitro (filter-grown Caco-2 monolayers) and an in vivo (mouse intestinal perfusion) intestinal epithelial model system. LPS, at physiologically relevant concentrations (0 to 1 ng/mL), in the basolateral compartment produced a time-dependent increase in Caco-2 TJ permeability without inducing cell death. Intraperitoneal injection of LPS (0.1 mg/kg), leading to clinically relevant plasma concentrations, also caused a time-dependent increase in intestinal permeability in vivo. The LPS-induced increase in intestinal TJ permeability was mediated by an increase in enterocyte membrane TLR-4 expression and a TLR-4–dependent increase in membrane colocalization of membrane-associated protein CD14. In conclusion, these studies show for the first time that LPS causes an increase in intestinal permeability via an intracellular mechanism involving TLR-4–dependent up-regulation of CD14 membrane expression. PMID:23201091

  9. Modulation of intercellular junctions by cyclic-ADT peptides as a method to reversibly increase blood-brain barrier permeability.

    Science.gov (United States)

    Laksitorini, Marlyn D; Kiptoo, Paul K; On, Ngoc H; Thliveris, James A; Miller, Donald W; Siahaan, Teruna J

    2015-03-01

    It is challenging to deliver molecules to the brain for diagnosis and treatment of brain diseases. This is primarily because of the presence of the blood-brain barrier (BBB), which restricts the entry of many molecules into the brain. In this study, cyclic-ADT peptides (ADTC1, ADTC5, and ADTC6) have been shown to modify the BBB to enhance the delivery of marker molecules [e.g., (14) C-mannitol, gadolinium-diethylenetriaminepentacetate (Gd-DTPA)] to the brain via the paracellular pathways of the BBB. The hypothesis is that these peptides modulate cadherin interactions in the adherens junctions of the vascular endothelial cells forming the BBB to increase paracellular drug permeation. In vitro studies indicated that ADTC5 had the best profile to inhibit adherens junction resealing in Madin-Darby canine kidney cell monolayers in a concentration-dependent manner (IC50 = 0.3 mM) with a maximal response at 0.4 mM. Under the current experimental conditions, ADTC5 improved the delivery of (14) C-mannitol to the brain about twofold compared with the negative control in the in situ rat brain perfusion model. Furthermore, ADTC5 peptide increased in vivo delivery of Gd-DTPA to the brain of Balb/c mice when administered intravenously. In conclusion, ADTC5 has the potential to improve delivery of diagnostic and therapeutic agents to the brain.

  10. Overexpression of galectin-7 in mouse epidermis leads to loss of cell junctions and defective skin repair.

    Directory of Open Access Journals (Sweden)

    Gaëlle Gendronneau

    Full Text Available The proteins of the galectin family are implicated in many cellular processes, including cell interactions, polarity, intracellular trafficking, and signal transduction. In human and mouse, galectin-7 is almost exclusively expressed in stratified epithelia, notably in the epidermis. Galectin-7 expression is also altered in several human tumors of epithelial origin. This study aimed at dissecting the consequences of galectin-7 overexpression on epidermis structure and functions in vivo.We established transgenic mice specifically overexpressing galectin-7 in the basal epidermal keratinocytes and analyzed the consequences on untreated skin and after UVB irradiation or mechanical injury.The intercellular cohesion of the epidermis is impaired in transgenic animals, with gaps developing between adjacent keratinocytes, associated with loss of adherens junctions. The epidermal architecture is aberrant with perturbations in the multilayered cellular organisation of the tissue, and structural defects in the basement membrane. These transgenic animals displayed a reduced re-epithelialisation potential following superficial wound, due to a defective collective migration of keratinocytes. Finally, a single mild dose of UVB induced an abnormal apoptotic response in the transgenic epidermis.These results indicate that an excess of galectin-7 leads to a destabilisation of adherens junctions associated with defects in epidermal repair. As this phenotype shares similarities with that of galectin-7 null mutant mice, we conclude that a critical level of this protein is required for maintaining proper epidermal homeostasis. This study brings new insight into the mode of action of galectins in normal and pathological situations.

  11. Unique cell type-specific junctional complexes in vascular endothelium of human and rat liver sinusoids.

    Directory of Open Access Journals (Sweden)

    Cyrill Géraud

    Full Text Available Liver sinusoidal endothelium is strategically positioned to control access of fluids, macromolecules and cells to the liver parenchyma and to serve clearance functions upstream of the hepatocytes. While clearance of macromolecular debris from the peripheral blood is performed by liver sinusoidal endothelial cells (LSECs using a delicate endocytic receptor system featuring stabilin-1 and -2, the mannose receptor and CD32b, vascular permeability and cell trafficking are controlled by transcellular pores, i.e. the fenestrae, and by intercellular junctional complexes. In contrast to blood vascular and lymphatic endothelial cells in other organs, the junctional complexes of LSECs have not yet been consistently characterized in molecular terms. In a comprehensive analysis, we here show that LSECs express the typical proteins found in endothelial adherens junctions (AJ, i.e. VE-cadherin as well as α-, β-, p120-catenin and plakoglobin. Tight junction (TJ transmembrane proteins typical of endothelial cells, i.e. claudin-5 and occludin, were not expressed by rat LSECs while heterogenous immunreactivity for claudin-5 was detected in human LSECs. In contrast, junctional molecules preferentially associating with TJ such as JAM-A, B and C and zonula occludens proteins ZO-1 and ZO-2 were readily detected in LSECs. Remarkably, among the JAMs JAM-C was considerably over-expressed in LSECs as compared to lung microvascular endothelial cells. In conclusion, we show here that LSECs form a special kind of mixed-type intercellular junctions characterized by co-occurrence of endothelial AJ proteins, and of ZO-1 and -2, and JAMs. The distinct molecular architecture of the intercellular junctional complexes of LSECs corroborates previous ultrastructural findings and provides the molecular basis for further analyses of the endothelial barrier function of liver sinusoids under pathologic conditions ranging from hepatic inflammation to formation of liver metastasis.

  12. Microcystin-Leucine Arginine Causes Cytotoxic Effects in Sertoli Cells Resulting in Reproductive Dysfunction in Male Mice

    Science.gov (United States)

    Chen, Yabing; Zhou, Yuan; Wang, Jing; Wang, Lihui; Xiang, Zou; Li, Dongmei; Han, Xiaodong

    2016-01-01

    Microcystin-leucine arginine (MC-LR) is a potent toxin for Sertoli cells. However, the specific molecular mechanisms of MC-induced cytotoxicity still remain unclear. In this study, we performed a comprehensive analyses of changes of miRNAs and mRNAs in Sertoli cells treated with MC-LR. Through computational approaches, we showed the pivotal roles of differentially expressed miRNAs that were associated with cell metabolism, cellular growth and proliferation, cell-to-cell signaling and interaction and cellular movement. Ingenuity Pathway Analyses (IPA) revealed some differentially expressed miRNAs and mRNAs that may cause reproductive system diseases. Target gene analyses suggested that destruction in tight junctions (TJ) and adherens junctions (AJ) in testes may be mediated by miRNAs. Consistent with a significant enrichment of chemokine signaling pathways, we observed numerous macrophages in the testes of mice following treatment with MC-LR, which may cause testicular inflammation. Moreover, miR-98-5p and miR-758 were predicted to bind the 3′-UTR region of the mitogen-activated protein kinase 11 (MAPK11, p38 β isoform) gene which stimulates tumor necrosis factor-α (TNF-α) expression in Sertoli cells. TNF-α could interact with the tumor necrosis factor receptor 1 (TNFR1) on germ cells leading to induction of germ cell apoptosis. Collectively, our integrated miRNA/mRNA analyses provided a molecular paradigm, which was experimentally validated, for understanding MC-LR-induced cytotoxicity. PMID:27976743

  13. Magnetic tunnel junctions (MTJs)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We review the giant tunnel magnetoresistance (TMR) in ferromagnetic-insulator-ferromagnetic junctions discovered in recent years, which is the magnetoresistance (MR) associated with the spin-dependent tunneling between two ferromagnetic metal films separated by an insulating thin tunnel barrier. The theoretical and experimental results including junction conductance, magnetoresistance and their temperature and bias dependences are described.

  14. Stacked Josephson Junctions

    DEFF Research Database (Denmark)

    Madsen, Søren Find; Pedersen, Niels Falsig; Christiansen, Peter Leth

    2010-01-01

    Long Josephson junctions have for some time been considered as a source of THz radiation. Solitons moving coherently in the junctions is a possible source for this radiation. Analytical computations of the bunched state and bunching-inducing methods are reviewed. Experiments showing THz radiation...

  15. Gap junction communication in myelinating glia.

    Science.gov (United States)

    Nualart-Marti, Anna; Solsona, Carles; Fields, R Douglas

    2013-01-01

    Gap junction communication is crucial for myelination and axonal survival in both the peripheral nervous system (PNS) and central nervous system (CNS). This review examines the different types of gap junctions in myelinating glia of the PNS and CNS (Schwann cells and oligodendrocytes respectively), including their functions and involvement in neurological disorders. Gap junctions mediate intercellular communication among Schwann cells in the PNS, and among oligodendrocytes and between oligodendrocytes and astrocytes in the CNS. Reflexive gap junctions mediating transfer between different regions of the same cell promote communication between cellular compartments of myelinating glia that are separated by layers of compact myelin. Gap junctions in myelinating glia regulate physiological processes such as cell growth, proliferation, calcium signaling, and participate in extracellular signaling via release of neurotransmitters from hemijunctions. In the CNS, gap junctions form a glial network between oligodendrocytes and astrocytes. This transcellular communication is hypothesized to maintain homeostasis by facilitating restoration of membrane potential after axonal activity via electrical coupling and the re-distribution of potassium ions released from axons. The generation of transgenic mice for different subsets of connexins has revealed the contribution of different connexins in gap junction formation and illuminated new subcellular mechanisms underlying demyelination and cognitive defects. Alterations in metabolic coupling have been reported in animal models of X-linked Charcot-Marie-Tooth disease (CMTX) and Pelizaeus-Merzbarcher-like disease (PMLD), which are caused by mutations in the genes encoding for connexin 32 and connexin 47 respectively. Future research identifying the expression and regulation of gap junctions in myelinating glia is likely to provide a better understanding of myelinating glia in nervous system function, plasticity, and disease. This

  16. Characterization and significance of adhesion and junction-related proteins in mouse ovarian follicles.

    Science.gov (United States)

    Mora, Jocelyn M; Fenwick, Mark A; Castle, Laura; Baithun, Marianne; Ryder, Timothy A; Mobberley, Margaret; Carzaniga, Raffaella; Franks, Stephen; Hardy, Kate

    2012-05-01

    In the ovary, initiation of follicle growth is marked by cuboidalization of flattened granulosa cells (GCs). The regulation and cell biology of this shape change remains poorly understood. We propose that characterization of intercellular junctions and associated proteins is key to identifying as yet unknown regulators of this important transition. As GCs are conventionally described as epithelial cells, this study used mouse ovaries and isolated follicles to investigate epithelial junctional complexes (tight junctions [TJ], adherens junctions [AJ], and desmosomes) and associated molecules, as well as classic epithelial markers, by quantitative PCR and immunofluorescence. These junctions were further characterized using ultrastructural, calcium depletion and biotin tracer studies. Junctions observed by transmission electron microscopy between GCs and between GCs and oocyte were identified as AJs by expression of N-cadherin and nectin 2 and by the lack of TJ and desmosome-associated proteins. Follicles were also permeable to biotin, confirming a lack of functional TJs. Surprisingly, GCs lacked all epithelial markers analyzed, including E-cadherin, cytokeratin 8, and zonula occludens (ZO)-1alpha+. Furthermore, vimentin was expressed by GCs, suggesting a more mesenchymal phenotype. Under calcium-free conditions, small follicles maintained oocyte-GC contact, confirming the importance of calcium-independent nectin at this stage. However, in primary and multilayered follicles, lack of calcium resulted in loss of contact between GCs and oocyte, showing that nectin alone cannot maintain attachment between these two cell types. Lack of classic markers suggests that GCs are not epithelial. Identification of AJs during GC cuboidalization highlights the importance of AJs in regulating initiation of follicle growth.

  17. Gap junction intercellular communication and benzene toxicity.

    Science.gov (United States)

    Rivedal, Edgar; Witz, Gisela; Leithe, Edward

    2010-03-19

    Aberrant regulation of gap junction intercellular communication (GJIC) has been linked to several human diseases, including cancer and abnormal hematopoietic development. Benzene exposure has been shown to cause hematotoxicity and leukemia, but the underlying mechanisms involved remain unclear. We have observed that several metabolites of benzene have the ability to block gap junction intercellular communication. The ring-opened trans,trans-muconaldehyde (MUC) was found to be the most potent inhibitor of gap junction channels. MUC was found to induce cross-linking of the gap junction protein connexin43, which seemed to be responsible for the induced inhibition of GJIC. Glutaraldehyde, which has a similar molecular structure as MUC, was found to possess similar effects on gap junctions as MUC, while the mono-aldehyde formaldehyde shows lower potency, both as a connexin cross-linker, and as an inhibitor of GJIC. Both glutaraldehyde and formaldehyde have previously been associated with induction of leukemia and disturbance of hematopoiesis. Taken together, the data support a possible link between the effect of MUC on gap junctions, and the toxic effects of benzene. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  18. ROCK2 primes the endothelium for vascular hyperpermeability responses by raising baseline junctional tension.

    Science.gov (United States)

    Beckers, Cora M L; Knezevic, Nebojsa; Valent, Erik T; Tauseef, Mohammad; Krishnan, Ramaswamy; Rajendran, Kavitha; Hardin, C Corey; Aman, Jurjan; van Bezu, Jan; Sweetnam, Paul; van Hinsbergh, Victor W M; Mehta, Dolly; van Nieuw Amerongen, Geerten P

    2015-07-01

    Rho kinase mediates the effects of inflammatory permeability factors by increasing actomyosin-generated traction forces on endothelial adherens junctions, resulting in disassembly of intercellular junctions and increased vascular leakage. In vitro, this is accompanied by the Rho kinase-driven formation of prominent radial F-actin fibers, but the in vivo relevance of those F-actin fibers has been debated, suggesting other Rho kinase-mediated events to occur in vascular leak. Here, we delineated the contributions of the highly homologous isoforms of Rho kinase (ROCK1 and ROCK2) to vascular hyperpermeability responses. We show that ROCK2, rather than ROCK1 is the critical Rho kinase for regulation of thrombin receptor-mediated vascular permeability. Novel traction force mapping in endothelial monolayers, however, shows that ROCK2 is not required for the thrombin-induced force enhancements. Rather, ROCK2 is pivotal to baseline junctional tension as a novel mechanism by which Rho kinase primes the endothelium for hyperpermeability responses, independent from subsequent ROCK1-mediated contractile stress-fiber formation during the late phase of the permeability response.

  19. Basolateral junction proteins regulate competition for the follicle stem cell niche in the Drosophila ovary.

    Science.gov (United States)

    Kronen, Maria R; Schoenfelder, Kevin P; Klein, Allon M; Nystul, Todd G

    2014-01-01

    Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs) in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl) or discs large (dlg), undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib), do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones.

  20. Basolateral junction proteins regulate competition for the follicle stem cell niche in the Drosophila ovary.

    Directory of Open Access Journals (Sweden)

    Maria R Kronen

    Full Text Available Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl or discs large (dlg, undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib, do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones.

  1. Alteration of cadherin isoform expression and inhibition of gap junctions in stomach carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To explore cell malignant phenotype correlated changes of cell surface adhesion molecules and cell-cell communication in carcinogenesis, human stomach transformed and cancer cell lines were investigated. Expressions of E-cadherin, N-cadherin, ?-catenin, ?-catenin as well as gap junction (GJ) protein Cx32 were studied by utilization of immunoblotting, immunocytochemical and fluorescent dye transfer methods. Mammalian normal stomach mucosal cells expressed E-cadherin but not N-cadherin. E-cadherin immunofluorescence was detected at cell membranous adherens junctions (AJ) where colocalization with immunofluorescent staining of inner surface adhesion plaque proteins ?- and ?-catenins was observed. The existence of E-cadherin/ catenin (?-, ?-) protein complexes as AJ was suggested. In transformed and stomach cancer cells E-cadherin was inhibited, instead, N-cadherin was expressed and localized at membranous AJ where co-staining with ?- and ?-catenin fluorescence was observed. Formation of N-cadherin/catenin (?-, ?-) protein complex at AJs of transformed and cancer cells was suggested. The above observations were further supported by immunoblotting results. Normal stomach muscosal and transformed cells expressed Cx32 at membranous GJ and were competent of gap junction communication (GJIC). In stomach cancer cells, Cx32 was inhibited and GJIC was defective. The results suggested that changes of signal pathways mediated by both cell adhesion and cell communication systems are associated intracellular events of stomach carcinogenesis. The alteration of cadherin isoform from E- to N-cadherin in transformed and stomach cancer cells is the first report.

  2. Slowdown promotes muscle integrity by modulating integrin-mediated adhesion at the myotendinous junction.

    Science.gov (United States)

    Gilsohn, Eliezer; Volk, Talila

    2010-03-01

    The correct assembly of the myotendinous junction (MTJ) is crucial for proper muscle function. In Drosophila, this junction comprises hemi-adherens junctions that are formed upon arrival of muscles at their corresponding tendon cells. The MTJ mainly comprises muscle-specific alphaPS2betaPS integrin receptors and their tendon-derived extracellular matrix ligand Thrombospondin (Tsp). We report the identification and functional analysis of a novel tendon-derived secreted protein named Slowdown (Slow). Homozygous slow mutant larvae exhibit muscle or tendon rupture, sluggish larval movement, partial lethality, and the surviving adult flies are unable to fly. These defects result from improper assembly of the embryonic MTJ. In slow mutants, Tsp prematurely accumulates at muscle ends, the morphology of the muscle leading edge changes and the MTJ architecture is aberrant. Slow was found to form a protein complex with Tsp. This complex is biologically active and capable of altering the morphology and directionality of muscle ends. Our analysis implicates Slow as an essential component of the MTJ, crucial for ensuring muscle and tendon integrity during larval locomotion.

  3. Equivalent Josephson junctions

    Science.gov (United States)

    Boyadjiev, T. L.; Semerdjieva, E. G.; Shukrinov, Yu. M.

    2008-01-01

    The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt-or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is adequate to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flow. This fact may explain the improvement of the spectra of microwave radiation noted in the literature.

  4. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  5. Gap junction diseases of the skin.

    NARCIS (Netherlands)

    Steensel, M.A.M. van

    2004-01-01

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by muta

  6. Gap junction diseases of the skin.

    NARCIS (Netherlands)

    Steensel, M.A.M. van

    2004-01-01

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by muta

  7. Significance of MR angiography in the diagnosis of aberrant renal arteries as the cause of ureteropelvic junction obstruction in children; Stellenwert der MR-Angiografie in der Diagnostik aberrierender Nierenarterien als Ursache einer Ureterabgangsstenose bei Kindern

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, L.; Sorge, I.; Hirsch, F.W.; Vieweger, A. [Leipzig Univ. (Germany). Dept. of Pediatric Radiology; Goetz, G.; Lehnert, T.; Buehligen, U.; Geyer, C. [Leipzig Univ. (Germany). Dept. of Pediatric Surgery

    2015-01-15

    To determine the importance of MRI with contrast-enhanced MRA for the detection or exclusion of aberrant or obstructing renal arteries in ureteropelvic junction obstruction in children. Key word-based search in RIS database (ureteropelvic junction obstruction/MRI) and retrospective comparison of arterial findings from preoperative contrast-enhanced MRA and intra-operative inspection. From 2007 to 2013, 19 children with ureteropelvic junction obstruction underwent contrast-enhanced MRA. Based on the results of the MRI scan and MAG3 scintigraphy, the children were referred to surgery (Anderson-Hynes-pyeloplasty). An aberrant renal artery was diagnosed with MRI in 14 of 19 children, and intra-operative inspection confirmed 13 of those 14. In the remaining 5 children, no aberrant vessel could be observed in MRI and this was confirmed intra-operatively in 3 of the 5 cases, while in the remaining 2, an aberrant vessel was found. Of the 14 children with aberrant vessels, 12 underwent surgery due to assumed ureteral obstruction, which was confirmed by surgery in 11 cases. In one case, an aberrant artery was found intra-operatively, but obstruction could not be confirmed. In one of the 14 children, the vessel was found in MRI, but its obstructing character was negated via MRA, which was confirmed intra-operatively. In the diagnosis of aberrant and obstructing renal arteries, contrast-enhanced MRA presents 85 % sensitivity and 80 % specificity, with a positive predictive value of 0.8. MRI with contrast-enhanced MRA is suitable to detect aberrant and obstructing renal arteries. An obstructive effect of the aberrant vessel is to be assumed if the vessel has a close relationship to the ureteropelvic junction and if it is linearly stretched.

  8. Gap junction diseases of the skin.

    Science.gov (United States)

    van Steensel, M A M

    2004-11-15

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by mutations in one of the genes coding for the constituent proteins of gap junctions, known as connexins. In this review, the currently known connexin disorders that feature skin abnormalities are described: keratitis-ichthyosis deafness syndrome, erythrokeratoderma variabilis, Vohwinkel's syndrome, and a novel disorder called hypotrichosis-deafness syndrome. What is known about the pathogenesis of these disorders is discussed and related to gap junction physiology. (c) 2004 Wiley-Liss, Inc.

  9. Ephrin-Bs Drive Junctional Downregulation and Actin Stress Fiber Disassembly to Enable Wound Re-epithelialization.

    Science.gov (United States)

    Nunan, Robert; Campbell, Jessica; Mori, Ryoichi; Pitulescu, Mara E; Jiang, Wen G; Harding, Keith G; Adams, Ralf H; Nobes, Catherine D; Martin, Paul

    2015-11-17

    For a skin wound to successfully heal, the cut epidermal-edge cells have to migrate forward at the interface between scab and healthy granulation tissue. Much is known about how lead-edge cells migrate, but very little is known about the mechanisms that enable active participation by cells further back. Here we show that ephrin-B1 and its receptor EphB2 are both upregulated in vivo, just for the duration of repair, in the first 70 or so rows of epidermal cells, and this signal leads to downregulation of the molecular components of adherens and tight (but not desmosomal) junctions, leading to loosening between neighbors and enabling shuffle room among epidermal cells. Additionally, this signaling leads to the shutdown of actomyosin stress fibers in these same epidermal cells, which may act to release tension within the wound monolayer. If this signaling axis is perturbed, then disrupted healing is a consequence in mouse and man.

  10. The human myotendinous junction

    DEFF Research Database (Denmark)

    Knudsen, A B; Larsen, M; Mackey, Abigail

    2015-01-01

    The myotendinous junction (MTJ) is a specialized structure in the musculotendinous system, where force is transmitted from muscle to tendon. Animal models have shown that the MTJ takes form of tendon finger-like processes merging with muscle tissue. The human MTJ is largely unknown and has never ...

  11. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: thierry.melin@isen.iemn.univ-lille1.fr [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-11-28

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  12. Junction trees of general graphs

    Institute of Scientific and Technical Information of China (English)

    Xiaofei WANG; Jianhua GUO

    2008-01-01

    In this paper,we study the maximal prime subgraphs and their corresponding structure for any undirected graph.We introduce the notion of junction trees and investigate their structural characteristics,including junction properties,induced-subtree properties,running-intersection properties and maximum-weight spanning tree properties.Furthermore,the characters of leaves and edges on junction trees are discussed.

  13. Internal resonances in periodically modulated long Josephson junctions

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Mygind, Jesper; Ustinov, Alexey V.

    1995-01-01

    Current-voltage (I-V) characteristics of long Josephson junctions with a periodic lattice of localized inhomogeneities are studied. The interaction between the moving fluxons and the inhomogeneities causes resonant steps in the IV-curve. Some of these steps are due to a synchronization to resonan...... into account the interaction between the resonance in the sub-junction and the magnetic flux density waves excited in the whole junction is given....... Fiske modes in the sub-junctions formed between the inhomogeneities. The voltage positions of the resonant steps oscillate as function of the applied magnetic field with a period corresponding to the inclusion of one magnetic flux quantum, Φ0=h/2e, per sub-junction. A qualitative explanation that takes...

  14. Visualizing supercurrents in 0-{pi} ferromagnetic Josephson tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Goldobin, Edward; Guerlich, Christian; Gaber, Tobias; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Collective Quantum Phenomena, Universitaet Tuebingen (Germany); Weides, Martin; Kohlstedt, Hermann [Institute of Solid State Physics, Reserch Center Juelich (Germany)

    2009-07-01

    So-called 0 and {pi} Josephson junctions can be treated as having positive and negative critical currents. This implies that the same phase shift applied to a Josephson junction causes counterflow of supercurrents in 0 and in {pi} junctions connected in parallel provided they are short in comparison with Josephson penetration depth {lambda}{sub J}. We have fabricated several 0, {pi}, 0-{pi}, 0-{pi}-0 and 20 x (0-{pi}-) planar superconductor-insulator-ferromagnet-superconductor Josephson junctions and studied the spatial supercurrent density distribution j{sub s}(x,y) across the junction area using low temperature scanning electron microscopy. At zero magnetic field we clearly see counterflow of the supercurrents in 0 and {pi} regions. The picture also changes consistently in the applied magnetic field.

  15. Mechanical tugging force regulates the size of cell–cell junctions

    Science.gov (United States)

    Liu, Zhijun; Tan, John L.; Cohen, Daniel M.; Yang, Michael T.; Sniadecki, Nathan J.; Ruiz, Sami Alom; Nelson, Celeste M.; Chen, Christopher S.

    2010-01-01

    Actomyosin contractility affects cellular organization within tissues in part through the generation of mechanical forces at sites of cell–matrix and cell–cell contact. While increased mechanical loading at cell–matrix adhesions results in focal adhesion growth, whether forces drive changes in the size of cell–cell adhesions remains an open question. To investigate the responsiveness of adherens junctions (AJ) to force, we adapted a system of microfabricated force sensors to quantitatively report cell–cell tugging force and AJ size. We observed that AJ size was modulated by endothelial cell–cell tugging forces: AJs and tugging force grew or decayed with myosin activation or inhibition, respectively. Myosin-dependent regulation of AJs operated in concert with a Rac1, and this coordinated regulation was illustrated by showing that the effects of vascular permeability agents (S1P, thrombin) on junctional stability were reversed by changing the extent to which these agents coupled to the Rac and myosin-dependent pathways. Furthermore, direct application of mechanical tugging force, rather than myosin activity per se, was sufficient to trigger AJ growth. These findings demonstrate that the dynamic coordination of mechanical forces and cell–cell adhesive interactions likely is critical to the maintenance of multicellular integrity and highlight the need for new approaches to study tugging forces. PMID:20463286

  16. Tight junction modulation of the blood brain barrier: CNS delivery of small molecules.

    Science.gov (United States)

    Greene, Chris; Campbell, Matthew

    2016-01-01

    The blood brain barrier (BBB) represents a major obstacle for targeted drug delivery to the brain for the treatment of central nervous system (CNS) disorders. Significant advances in barrier research over the past decade has led to the discovery of an increasing number of structural and regulatory proteins in tight junctions (TJ) and adherens junctions (AJ). These discoveries are providing the framework for the development of novel TJ modulators which can act specifically and temporarily to alter BBB function and regulate paracellular uptake of molecules. TJ modulators that have shown therapeutic potential in preclinical models include claudin-5 and occludin siRNAs, peptides derived from zonula occludens toxin as well as synthetic peptides targeting the extracellular loops of TJs. Adding to the array of modulating agents are novel mechanisms of BBB regulation such as focused ultrasound (FUS). This review will give a succinct overview of BBB biology and TJ modulation in general. Novel insights into BBB regulation in health and disease will also be summarized.

  17. Potent In Vitro Protection Against PM₂.₅-Caused ROS Generation and Vascular Permeability by Long-Term Pretreatment with Ganoderma tsugae.

    Science.gov (United States)

    Tseng, Chia-Yi; Chung, Meng-Chi; Wang, Jhih-Syuan; Chang, Yu-Jung; Chang, Jing-Fen; Lin, Chin-Hung; Hseu, Ruey-Shyang; Chao, Ming-Wei

    2016-01-01

    Epidemiological studies show increased particulate matter (PM[Formula: see text]) particles in ambient air are correlated with increased myocardial infarctions. Given the close association of capillaries and alveoli, the dysfunction is caused when inhaled PM[Formula: see text] particles come in close proximity to capillary endothelial cells. We previously suggested that the inhalation of PM[Formula: see text] diesel exhaust particles (DEP) induces oxidative stress and upregulates the Nrf2/HO-1 pathway, inducing vascular permeability factor VEGFA secretion, which results in cell-cell adherens junction disruption and PM[Formula: see text] transmigratation into circulation. Here, we minimized the level that PM[Formula: see text] traveled in the bloodstream by pre-supplementing with a traditional Chinese medicine (TCM) Ganoderma tsugae DMSO extract (GTDE) prior to PM[Formula: see text] exposure. Our results show that PM[Formula: see text] caused alterations in enzyme activities and cellular anti-oxidant balance. We found decreased glutathione levels, a reduced cellular redox ratio, increased ROS generation and cytotoxicity in the cellular fractions. The oxidative stress caused DNA damage and apoptosis, likely causing downstream molecular events that trigger vasculature permeabilization and, eventually, cardiovascular disorders. Our results show long-term GTDE treatment increased endogenous glutathione level, while PM[Formula: see text]-reduced glutathione levels and the cellular redox ratio. GTDE was protective against the genotoxic and apoptotic effects initiated by PM[Formula: see text] oxidative stress. Vascular permeability revealed that PM[Formula: see text] only accumulated on the surface of cells after GTDE treatment; no penetration was detected. After two weeks of GTDE treatment, VEGFA secretion was significantly reduced in human umbilical vein endothelial cells (HUVEC) and endothelial cell migration was blocked. Our results suggest GTDE prevents PM

  18. Junction conditions of cosmological perturbations

    CERN Document Server

    Tomita, K

    2004-01-01

    The behavior of perturbations is studied in cosmological models which consist of two different homogeneous regions connected in a spherical shell boundary. The junction conditions for the metric perturbations and the displacements of the shell boundary are analyzed and the surface densities of the perturbed energy and momentum in the shell are derived, using Mukohyama's gauge-invariant formalism and the Israel discontinuity condition. In both homogeneous regions the perturbations of scalar, vector and tensor types are expanded using the 3-dimensional harmonic functions, but the model coupling among them is caused in the shell by the inhomogeneity. By treating the perturbations with odd and even parities separately, it is found, however, that we can have consistent displacements and surface densities for given metric parturbations

  19. The stardust family protein MPP7 forms a tripartite complex with LIN7 and DLG1 that regulates the stability and localization of DLG1 to cell junctions.

    Science.gov (United States)

    Bohl, Joanna; Brimer, Nicole; Lyons, Charles; Vande Pol, Scott B

    2007-03-30

    MPP7, a previously uncharacterized member of the p55 Stardust family of membrane-associated guanylate kinase (MAGUK) proteins, was found in a tripartite complex with DLG1 and LIN7A or LIN7C. MPP7 dimerizes with all three LIN7 family members (LIN7A, -B, and -C) through interaction of the single L27 domain of LIN7 with the carboxyl-terminal L27 domain of MPP7, thereby stabilizing both proteins. The dimer of MPP7 with LIN7A or LIN7C associates with DLG1 through an interaction requiring the amino-terminal L27 domain of MPP7. The amino-terminal L27 domain of MPP7 is not sufficient for interaction with DLG1 but interacts efficiently only if MPP7 is in a complex with LIN7A or -C. Thus the specificity of interaction of DLG1 with the LIN7-MPP7 complex is determined by L27 interactions with both MPP7 and LIN7. The tripartite complex forms in a ratio of 1:1:1 and localizes to epithelial adherens junctions in a manner dependent upon MPP7. Expression of MPP7 stabilizes DLG1 in an insoluble compartment. Expression of MPP7 deleted of the PDZ or Src homology 3 domain redistributes MPP7, DLG1, and LIN7 out of adherens junctions and into the soluble cytoplasmic fraction without changing the localization of E-cadherin. Thus, the stability and localization of DLG1 to cell-cell junctions are complex functions determined by the expression and association of particular Stardust family members together with particular LIN7 family members.

  20. Holliday junction resolvases.

    Science.gov (United States)

    Wyatt, Haley D M; West, Stephen C

    2014-09-02

    Four-way DNA intermediates, called Holliday junctions (HJs), can form during meiotic and mitotic recombination, and their removal is crucial for chromosome segregation. A group of ubiquitous and highly specialized structure-selective endonucleases catalyze the cleavage of HJs into two disconnected DNA duplexes in a reaction called HJ resolution. These enzymes, called HJ resolvases, have been identified in bacteria and their bacteriophages, archaea, and eukaryotes. In this review, we discuss fundamental aspects of the HJ structure and their interaction with junction-resolving enzymes. This is followed by a brief discussion of the eubacterial RuvABC enzymes, which provide the paradigm for HJ resolvases in other organisms. Finally, we review the biochemical and structural properties of some well-characterized resolvases from archaea, bacteriophage, and eukaryotes. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  1. Wireless Josephson Junction Arrays

    Science.gov (United States)

    Adams, Laura

    2015-03-01

    We report low temperature, microwave transmission measurements on a wireless two- dimensional network of Josephson junction arrays composed of superconductor-insulator -superconductor tunnel junctions. Unlike their biased counterparts, by removing all electrical contacts to the arrays and superfluous microwave components and interconnects in the transmission line, we observe new collective behavior in the transmission spectra. In particular we will show emergent behavior that systematically responds to changes in microwave power at fixed temperature. Likewise we will show the dynamic and collective response of the arrays while tuning the temperature at fixed microwave power. We discuss these spectra in terms of the Berezinskii-Kosterlitz-Thouless phase transition and Shapiro steps. We gratefully acknowledge the support Prof. Steven Anlage at the University of Maryland and Prof. Allen Goldman at the University of Minnesota. Physics and School of Engineering and Applied Sciences.

  2. Decreased Vision and Junctional Scotoma from Pituicytoma

    Directory of Open Access Journals (Sweden)

    Nancy Huynh

    2012-05-01

    Full Text Available Pituicytomas are rare neoplasms of the sellar region. We report a case of vision loss and a junctional scotoma in a 43-year-old woman caused by compression of the optic chiasm by a pituitary tumor. The morphological and immunohistochemical characteristics of the tumor were consistent with the diagnosis of pituicytoma. The tumor was debulked surgically, and the patient’s vision improved.

  3. Brownian refrigeration by hybrid tunnel junctions

    OpenAIRE

    Peltonen, J. T.; Helle, M.; Timofeev, A. V.; Solinas, P.; Hekking, F. W. J.; Pekola, Jukka P.

    2011-01-01

    Voltage fluctuations generated in a hot resistor can cause extraction of heat from a colder normal metal electrode of a hybrid tunnel junction between a normal metal and a superconductor. We extend the analysis presented in Phys. Rev. Lett. 98, 210604 (2007) of this heat rectifying system, bearing resemblance to a Maxwell’s demon. Explicit analytic calculations show that the entropy of the total system is always increasing. We then consider a single-electron transistor configuration with two ...

  4. An induced junction photovoltaic cell

    Science.gov (United States)

    Call, R. L.

    1974-01-01

    Silicon solar cells operating with induced junctions rather than diffused junctions have been fabricated and tested. Induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. Measurements of the response of the inversion layer cell to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. The greater sensitivity occurs because of the shallow junction and the strong electric field at the surface.

  5. Current distributions in stripe Majorana junctions

    Science.gov (United States)

    Osca, Javier; Llorenç, Serra

    2017-02-01

    We calculate current and density distributions in stripe (2D planar) junctions between normal and Majorana nanowires having a finite ( y) transverse length. In presence of a magnetic field with vertical and in-plane components, the y-symmetry of the charge current distribution in the normal lead changes strongly across the Majorana phase transition: from center-symmetric if a Majorana mode is present to laterally-shifted (as expected by the Hall effect) if the field is tilted such as to destroy the Majorana mode due to the projection rule. We compare quasi-particle and charge distributions of current and density, as well as spin magnetizations. The Majorana mode causes opposite spin accumulations on the transverse sides of the junction and the emergence of a spin current.

  6. An Important Member of Tight Junctions: Claudins

    Directory of Open Access Journals (Sweden)

    Ozlem Demirpence

    2016-01-01

    Full Text Available The tight junction (TJs, the most apically located of the intercellular junctional complexes, inhibits solute and water flow through the paracellular space, termed the %u201Cbarrier%u201D function. TJs participate in signal transduction mechanisms that regulate epithelial cell proliferation, gene expression, differentiation and morphogenesis. The claudin family of transmembrane proteins localized to the TJ. Loss of expression of Claudin causes of suppression TJs function. Recent studies have shown that altered levels of the different claudins may be related to invasion and progression of carcinoma cells in several primary neoplasms. A better knowledge of the mechanisms underlying carcinogenesis will likely result in the development of novel approaches for the diagnosis and therapy.

  7. Mixing in T-junctions

    NARCIS (Netherlands)

    Kok, Jacobus B.W.; van der Wal, S.

    1996-01-01

    The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction

  8. Metallic Junction Thermoelectric Device Simulations

    Science.gov (United States)

    Duzik, Adam J.; Choi, Sang H.

    2017-01-01

    Thermoelectric junctions made of semiconductors have existed in radioisotope thermoelectric generators (RTG) for deep space missions, but are currently being adapted for terrestrial energy harvesting. Unfortunately, these devices are inefficient, operating at only 7% efficiency. This low efficiency has driven efforts to make high-figure-of-merit thermoelectric devices, which require a high electrical conductivity but a low thermal conductivity, a combination that is difficult to achieve. Lowered thermal conductivity has increased efficiency, but at the cost of power output. An alternative setup is to use metallic junctions rather than semiconductors as thermoelectric devices. Metals have orders of magnitude more electrons and electronic conductivities higher than semiconductors, but thermal conductivity is higher as well. To evaluate the viability of metallic junction thermoelectrics, a two dimensional heat transfer MATLAB simulation was constructed to calculate efficiency and power output. High Seebeck coefficient alloys, Chromel (90%Ni-10%Cr) and Constantan (55%Cu-45%Ni), produced efficiencies of around 20-30%. Parameters such as the number of layers of junctions, lateral junction density, and junction sizes for both series- and parallel-connected junctions were explored.

  9. Evolution and cell physiology. 4. Why invent yet another protein complex to build junctions in epithelial cells?

    Science.gov (United States)

    Le Bivic, André

    2013-12-15

    The formation of the first epithelium was an essential step for animal evolution, since it has allowed coordination of the behavior of a cell layer and creation of a selective barrier between the internal medium and the outside world. The possibility of coupling the cells in a single layer has allowed morphogenetic events, such as tube formation, or gastrulation, to form more complex animal morphologies. The invention of sealed junctions between cells has allowed, on the other hand, creation of an asymmetry of nutrients or salts between the apical and the basal side of the epithelial layer. Creation of an internal medium has led to homeostasis, allowing the evolution of more complex physiological functions and the emergence of sophisticated animal shapes. During evolution, the origins of the first animals coincided with the invention of several protein complexes, including true cadherins and the polarity protein complexes. How these complexes regulate formation of the apicolateral border and the adherens junctions is still not fully understood. This review focuses on the role of these apical polarity complexes and, in particular, the Crumbs complex, which is essential for proper organization of epithelial layers from Drosophila to humans.

  10. ADAM10 Is Involved in Cell Junction Assembly in Early Porcine Embryo Development.

    Directory of Open Access Journals (Sweden)

    Jeongwoo Kwon

    Full Text Available ADAM10 (A Disintegrin and Metalloprotease domain-containing protein 10 is a cell surface protein with a unique structure possessing both potential adhesion and protease domains. However, the role of ADAM10 in preimplantation stage embryos is not clear. In this study, we examined the expression patterns and functional roles of ADAM10 in porcine parthenotes during preimplantation development. The transcription level of ADAM10 dramatically increased from the morula stage onward. Immunostaining revealed that ADAM10 was present in both the nucleus and cytoplasm in early cleavage stage embryos, and localized to the apical region of the outer cells in morula and blastocyst embryos. Knockdown (KD of ADAM10 using double strand RNA did not alter preimplantation embryo development until morula stage, but resulted in significantly reduced development to blastocyst stage. Moreover, the KD blastocyst showed a decrease in gene expression of adherens and tight junction (AJ/TJ, and an increase in trophectoderm TJ permeability by disrupting TJ assembly. Treatment with an ADAM10 specific chemical inhibitor, GI254023X, at the morula stage also inhibited blastocyst development and led to disruption of TJ assembly. An in situ proximity ligation assay demonstrated direct interaction of ADAM10 with coxsackie virus and adenovirus receptor (CXADR, supporting the involvement of ADAM10 in TJ assembly. In conclusion, our findings strongly suggest that ADADM10 is important for blastocyst formation rather than compaction, particularly for TJ assembly and stabilization in preimplantation porcine parthenogenetic development.

  11. The connexin43 carboxyl terminus and cardiac gap junction organization.

    Science.gov (United States)

    Palatinus, Joseph A; Rhett, J Matthew; Gourdie, Robert G

    2012-08-01

    The precise spatial order of gap junctions at intercalated disks in adult ventricular myocardium is thought vital for maintaining cardiac synchrony. Breakdown or remodeling of this order is a hallmark of arrhythmic disease of the heart. The principal component of gap junction channels between ventricular cardiomyocytes is connexin43 (Cx43). Protein-protein interactions and modifications of the carboxyl-terminus of Cx43 are key determinants of gap junction function, size, distribution and organization during normal development and in disease processes. Here, we review data on the role of proteins interacting with the Cx43 carboxyl-terminus in the regulation of cardiac gap junction organization, with particular emphasis on Zonula Occludens-1. The rapid progress in this area suggests that in coming years we are likely to develop a fuller understanding of the molecular mechanisms causing pathologic remodeling of gap junctions. With these advances come the promise of novel approach to the treatment of arrhythmia and the prevention of sudden cardiac death. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Demonstrated Anomalous Pancreaticobiliary Ductal Junction

    OpenAIRE

    Koçkar, Cem; ?ENOL, Altu?; BA?TÜRK, Abdulkadir; AYDIN, Bünyamin; Cüre, Erkan

    2015-01-01

    Anomalies of the pancreaticobiliary junction are rare. Clinically anomalies of the pancreaticobiliary junction are uncommonly symptomatic but may present themselves with associated conditions ranging from benign acute abdominal pain to carcinomas. A 52 years old man was admitted to gastroenterology service with complaints of fever, nausea, vomiting and recurrent epigastric pain. He was diagnosed with biliary pancreatitis. Endoscopic retrograde cholangiopancreato-graphy was performed. Papilla ...

  13. Josephson junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Georg Hermann

    2012-03-04

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  14. Electronic thermometry in tunable tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  15. Thermal Spin Transfer in Fe-MgO-Fe Tunnel Junctions

    NARCIS (Netherlands)

    Jia, X.; Xia, K.; Bauer, G.E.W.

    2011-01-01

    We compute thermal spin transfer (TST) torques in Fe-MgO-Fe tunnel junctions using a first principles wave-function-matching method. At room temperature, the TST in a junction with 3 MgO monolayers amounts to 10-7  J/m2/K, which is estimated to cause magnetization reversal for temperature difference

  16. Changes of junctions of endothelial cells in coronary sclerosis:A review

    Institute of Scientific and Technical Information of China (English)

    Li-Zi Zhang; Sun Lei

    2016-01-01

    Atherosclerosis, the major cause of cardiovascular diseases, has been a leading contributor to morbidity and mortality in the United States and it has been on the rise globally. Endothelial cellecell junctions are critical for vascular integrity and maintenance of vascular function. Endothelial cell junctions dysfunction is the onset step of future coronary events and coronary artery dis-ease.

  17. Double Trouble: A Rare Case of Bilateral Upper Pole Ureteropelvic Junction Obstruction

    Directory of Open Access Journals (Sweden)

    Craig A. Peters

    2014-09-01

    Full Text Available A 16-year-old girl presented with bilateral back pain caused by bilateral upper pole ureteropelvic junction obstructions; an extremely rare phenomenon. Bilateral robotically assisted upper pole pyeloplasties were preformed at the same setting with an excellent clinical response. Although rare, upper pole ureteropelvic junction obstruction is a defined entity that urologists should be aware of.

  18. Altered expression of epithelial junctional proteins in atopic asthma: Possible role in inflammation

    NARCIS (Netherlands)

    W.I. de Boer (Pim); H.S. Sharma (Hari); S.M. Baelemans (Sophia); H.C. Hoogsteden (Henk); B.N.M. Lambrecht (Bart); G.J. Braunstahl (Gert-Jan)

    2008-01-01

    textabstractEpithelial cells form a tight barrier against environmental stimuli via tight junctions (TJs) and adherence junctions (AJs). Defects in TJ and AJ proteins may cause changes in epithelial morphology and integrity and potentially lead to faster trafficking of inflammatory cells through the

  19. Octagonal Defects at Carbon Nanotube Junctions

    Science.gov (United States)

    Jaskólski, W.; Pelc, M.; Chico, Leonor; Ayuela, A.

    2013-01-01

    We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (EF). The reconstructed junction has only one state near EF, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system. PMID:24089604

  20. N-glycosylation controls the function of junctional adhesion molecule-A.

    Science.gov (United States)

    Scott, David W; Tolbert, Caitlin E; Graham, David M; Wittchen, Erika; Bear, James E; Burridge, Keith

    2015-09-15

    Junctional adhesion molecule-A (JAM-A) is an adherens and tight junction protein expressed by endothelial and epithelial cells. JAM-A serves many roles and contributes to barrier function and cell migration and motility, and it also acts as a ligand for the leukocyte receptor LFA-1. JAM-A is reported to contain N-glycans, but the extent of this modification and its contribution to the protein's functions are unknown. We show that human JAM-A contains a single N-glycan at N185 and that this residue is conserved across multiple mammalian species. A glycomutant lacking all N-glycans, N185Q, is able to reach the cell surface but exhibits decreased protein half-life compared with the wild- type protein. N-glycosylation of JAM-A is required for the protein's ability to reinforce barrier function and contributes to Rap1 activity. We further show that glycosylation of N185 is required for JAM-A-mediated reduction of cell migration. Finally, we show that N-glycosylation of JAM-A regulates leukocyte adhesion and LFA-1 binding. These findings identify N-glycosylation as critical for JAM-A's many functions. © 2015 Scott et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  1. Cervicomedullary neurocysticercosis causing obstructive hydrocephalus.

    Science.gov (United States)

    Wang, Doris D; Huang, Michael C

    2015-09-01

    We present a 45-year-old man with tussive headache and blurred vision found to have obstructive hydrocephalus from a neurocysticercal cyst at the cervicomedullary junction who underwent surgical removal of the cyst. We performed a suboccipital craniectomy to remove the cervicomedullary cyst en bloc. Cyst removal successfully treated the patient's headaches without necessitating permanent cerebrospinal fluid diversion. Neurocysticercosis is the most common parasite infection of the central nervous system causing seizures and, less commonly, hydrocephalus. Intraventricular cysts or arachnoiditis usually cause hydrocephalus in neurocysticercosis but craniocervical junction cysts causing obstructive hydrocephalus are rare. Neurocysticercosis at the craniocervical junction may cause Chiari-like symptoms. In the absence of arachnoiditis and leptomeningeal enhancement, surgical removal of the intact cyst can lead to favorable outcomes.

  2. Modelling of Dual-Junction Solar Cells including Tunnel Junction

    Directory of Open Access Journals (Sweden)

    Abdelaziz Amine

    2013-01-01

    Full Text Available Monolithically stacked multijunction solar cells based on III–V semiconductors materials are the state-of-art of approach for high efficiency photovoltaic energy conversion, in particular for space applications. The individual subcells of the multi-junction structure are interconnected via tunnel diodes which must be optically transparent and connect the component cells with a minimum electrical resistance. The quality of these diodes determines the output performance of the solar cell. The purpose of this work is to contribute to the investigation of the tunnel electrical resistance of such a multi-junction cell through the analysis of the current-voltage (J-V characteristics under illumination. Our approach is based on an equivalent circuit model of a diode for each subcell. We examine the effect of tunnel resistance on the performance of a multi-junction cell using minimization of the least squares technique.

  3. Electromechanical resistive switching via back-to-back Schottky junctions

    Science.gov (United States)

    Li, Lijie

    2015-09-01

    The physics of the electromechanical resistive switching is uncovered using the theory of back-to-back Schottky junctions combined with the quantum domain space charge transport. A theoretical model of the basic element of resistive switching devices realized by the metal-ZnO nanowires-metal structure has been created and analyzed. Simulation results show that the reverse biased Schottky junction and the air gap impedance dominate the current-voltage relation at higher external voltages; thereby electromechanically varying the air gap thickness causes the device exhibit resistive tuning characteristics. As the device dimension is in nanometre scale, investigation of the model based on quantum mechanics has also been conducted.

  4. Role of spectraplakin in Drosophila photoreceptor morphogenesis.

    Directory of Open Access Journals (Sweden)

    Uyen Ngoc Mui

    Full Text Available BACKGROUND: Crumbs (Crb, a cell polarity gene, has been shown to provide a positional cue for the apical membrane domain and adherens junction during Drosophila photoreceptor morphogenesis. It has recently been found that stable microtubules in developing Drosophila photoreceptors were linked to Crb localization. Coordinated interactions between microtubule and actin cytoskeletons are involved in many polarized cellular processes. Since Spectraplakin is able to bind both microtubule and actin cytoskeletons, the role of Spectraplakin was analyzed in the regulations of apical Crb domain in developing Drosophila photoreceptors. METHODOLOGY/PRINCIPAL FINDINGS: The localization pattern of Spectraplakin in developing pupal photoreceptors showed a unique intracellular distribution. Spectraplakin localized at rhabdomere terminal web which is at the basal side of the apical Crb or rhabdomere, and in between the adherens junctions. The spectraplakin mutant photoreceptors showed dramatic mislocalizations of Crb, adherens junctions, and the stable microtubules. This role of Spectraplakin in Crb and adherens junction regulation was further supported by spectraplakin's gain-of-function phenotype. Spectraplakin overexpression in photoreceptors caused a cell polarity defect including dramatic mislocalization of Crb, adherens junctions and the stable microtubules in the developing photoreceptors. Furthermore, a strong genetic interaction between spectraplakin and crb was found using a genetic modifier test. CONCLUSIONS/SIGNIFICANCE: In summary, we found a unique localization of Spectraplakin in photoreceptors, and identified the role of spectraplakin in the regulation of the apical Crb domain and adherens junctions through genetic mutational analysis. Our data suggest that Spectraplakin, an actin-microtubule cross-linker, is essential in the apical and adherens junction controls during the photoreceptors morphogenesis.

  5. Trichomonas vaginalis perturbs the junctional complex in epithelial cells

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Trichomonas vaginalis, a protist parasite of the urogenital tract in humans, is the causative agent of trichomonosis,which in recent years have been associated with the cervical cancer development. In the present study we analyzed the modifications at the junctional complex level of Caco-2 cells after interaction with two isolates of T. vaginalis and the influence of the iron concentration present in the parasite's culture medium on the interaction effects. Our results show that T. vaginalis adheres to the epithelial cell causing alterations in the junctional complex, such as: (a) a decrease in transepithelial electrical resistance; (b) alteration in the pattern of junctional complex proteins distribution as obseryed for E-cadherin, occludin and ZO-1; and (c) enlargement of the spaces between epithelial cells. These effects were dependent on (a) the degree of the parasite virulence isolate, (b) the iron concentration in the culture medium, and (c) the expression of adhesin proteins on the parasite surface.

  6. Gap junctions - guards of excitability.

    Science.gov (United States)

    Stroemlund, Line Waring; Jensen, Christa Funch; Qvortrup, Klaus; Delmar, Mario; Nielsen, Morten Schak

    2015-06-01

    Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances of the heart and focuses on the role of the gap junctional protein connexin 43 (Cx43). Current evidence shows that Cx43 plays a crucial role in organizing microtubules at the intercalated disc and thereby regulating the trafficking of the cardiac sodium channel NaV1.5 to the membrane.

  7. Molecular mechanisms of gap junction mutations in myelinating cells.

    Science.gov (United States)

    Sargiannidou, Irene; Markoullis, Kyriaki; Kleopa, Kleopas A

    2010-09-01

    There is an emerging group of neurological disorders that result from genetic mutations affecting gap junction proteins in myelinating cells. The X-linked form of Charcot Marie Tooth disease (CMT1X) is caused by numerous mutations in the GJB1 gene encoding the gap junction protein connexin32 (Cx32), which is expressed in both Schwann cells in the PNS and oligodendrocytes in the CNS. Patients with CMT1X present mainly with a progressive peripheral neuropathy, showing mixed axonal and demyelinating features. In many cases there is also clinical or subclinical involvement of the CNS with acute or chronic phenotypes of encephalopathy. Furthermore, mutations in the GJA12/GJC2 gene encoding the gap junction protein Cx47, which is expressed in oligodendrocytes, have been identified in families with progressive leukodystrophy, known as Pelizaeus-Merzbacher-like disease, as well as in patients with hereditary spastic paraplegia. Recent studies have provided insights into the pattern of gap junction protein expression and function in CNS and PNS myelinating cells. Furthermore, in vitro and in vivo disease models have clarified some of the molecular and cellular mechanisms underlying these disorders. Here we provide an overview of the clinical, genetic, and neurobiological aspects of gap junction disorders affecting the nervous system.

  8. Testosterone regulates tight junction proteins and influences prostatic autoimmune responses.

    Science.gov (United States)

    Meng, Jing; Mostaghel, Elahe A; Vakar-Lopez, Funda; Montgomery, Bruce; True, Larry; Nelson, Peter S

    2011-06-01

    Testosterone and inflammation have been linked to the development of common age-associated diseases affecting the prostate gland including prostate cancer, prostatitis, and benign prostatic hypertrophy. We hypothesized that testosterone regulates components of prostate tight junctions which serve as a barrier to inflammation, thus providing a connection between age- and treatment-associated testosterone declines and prostatic pathology. We examined the expression and distribution of tight junction proteins in prostate biospecimens from mouse models and a clinical study of chemical castration, using transcript profiling, immunohistochemistry, and electron microscopy. We determined that low serum testosterone is associated with reduced transcript and protein levels of Claudin 4 and Claudin 8, resulting in defective tight junction ultrastructure in benign prostate glands. Expression of Claudin 4 and Claudin 8 was negatively correlated with the mononuclear inflammatory infiltrate caused by testosterone deprivation. Testosterone suppression also induced an autoimmune humoral response directed toward prostatic proteins. Testosterone supplementation in castrate mice resulted in re-expression of tight junction components in prostate epithelium and significantly reduced prostate inflammatory cell numbers. These data demonstrate that tight junction architecture in the prostate is related to changes in serum testosterone levels, and identify an androgen-regulated mechanism that potentially contributes to the development of prostate inflammation and consequent pathology.

  9. A New Perspective on Intercalated Disc Organization: Implications for Heart Disease

    Directory of Open Access Journals (Sweden)

    Jifen Li

    2010-01-01

    Full Text Available Adherens junctions and desmosomes are intercellular adhesive junctions and essential for the morphogenesis, differentiation, and maintenance of tissues that are subjected to high mechanical stress, including heart and skin. The different junction complexes are organized at the termini of the cardiomyocyte called the intercalated disc. Disruption of adhesive integrity via mutations in genes encoding desmosomal proteins causes an inherited heart disease, arrhythmogenic right ventricular cardiomyopathy (ARVC. Besides plakoglobin, which is shared by adherens junctions and desmosomes, other desmosomal components, desmoglein-2, desmocollin-2, plakophilin-2, and desmoplakin are also present in ultrastructurally defined fascia adherens junctions of heart muscle, but not other tissues. This mixed-type of junctional structure is termed hybrid adhering junction or area composita. Desmosomal plakophilin-2 directly interacts with adherens junction protein alphaT-catenin, providing a new molecular link between the cadherin-catenin complex and desmosome. The area composita only exists in the cardiac intercalated disc of mammalian species suggesting that it evolved to strengthen mechanical coupling in the heart of higher vertebrates. The cross-talk among different junctions and their implication in the pathogenesis of ARVC are discussed in this review.

  10. Regulating cell-cell junctions from A to Z.

    Science.gov (United States)

    Hardin, Jeff

    2016-04-25

    Epithelial sheets often present a "cobblestone" appearance, but the mechanisms underlying the dynamics of this arrangement are unclear. In this issue, Choi et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201506115) show that afadin and ZO-1 regulate tension and maintain zonula adherens architecture in response to changes in contractility.

  11. Control over Rectification in Supramolecular Tunneling Junctions

    NARCIS (Netherlands)

    Wimbush, K.S.; Wimbush, Kim S.; Reus, William F.; van der Wiel, Wilfred Gerard; Reinhoudt, David; Whitesides, George M.; Nijhuis, C.A.; Velders, Aldrik

    2010-01-01

    In complete control: The magnitude of current rectification in well-defined supramolecular tunneling junctions can be controlled by changing the terminal functionality (red spheres) of dendrimers (gray spheres) immobilized on a supramolecular platform (see picture). Junctions containing biferrocene

  12. Nano-Molecular Junctions on STM Tips

    Institute of Scientific and Technical Information of China (English)

    Chun Huang∗; Jianshu Yang

    2011-01-01

    We present a technique for building metal-organic-metal junctions, which contain ten or fewer conjugated molecules between each of such junction, and the investigations of the I-V response of these junctions. The junctions are made by self assembling thiolated molecules onto gold coated tips for use in scanning tunneling microscopy. We show that this easy technique probes the qualitative properties of the molecules. Current-voltage characteristics of a Tour wire and a new molecular rectifier are presented.

  13. Nano-Molecular Junctions on STM Tips

    Institute of Scientific and Technical Information of China (English)

    Chun Huang; Jianshu Yang

    2011-01-01

    We present a technique for building metal-organic-metal junctions, which contain ten or fewer conjugated molecules between each of such junction, and the investigations of the I-V response of these junctions.The junctions are made by self assembling thiolated molecules onto gold coated tips for use in scanning tunneling microscopy. We show that this easy technique probes the qualitative properties of the molecules. Currentvoltage characteristics of a Tour wire and a new molecular rectifier are presented.

  14. Current noise in tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Frey, Moritz; Grabert, Hermann [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104, Freiburg (Germany)

    2017-06-15

    We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc bias...

  16. Stability of large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

    The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

  17. Soliton bunching in annular Josephson junctions

    DEFF Research Database (Denmark)

    Vernik, I.V; Lazarides, Nickos; Sørensen, Mads Peter

    1996-01-01

    By studying soliton (fluxon) motion in long annular Josephson junctions it is possible to avoid the influence of the boundaries and soliton-soliton collisions present in linear junctions. A new experimental design consisting of a niobium coil placed on top of an annular junction has been used...

  18. Long Range Magnetic Interaction between Josephson Junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    1995-01-01

    A new model for magnetic coupling between long Josephson junctions is proposed. The coupling mechanism is a result of the magnetic fields outside the junctions and is consequently effective over long distances between junctions. We give specific expressions for the form and magnitude of the inter...

  19. Dynamics of pi-junction interferometer circuits

    DEFF Research Database (Denmark)

    Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.;

    2002-01-01

    The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current...

  20. Dynamics of pi-junction interferometer circuits

    DEFF Research Database (Denmark)

    Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.

    2002-01-01

    The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current...

  1. Regulation of neuronal axon specification by glia-neuron gap junctions in C. elegans

    Science.gov (United States)

    Meng, Lingfeng; Zhang, Albert; Jin, Yishi; Yan, Dong

    2016-01-01

    Axon specification is a critical step in neuronal development, and the function of glial cells in this process is not fully understood. Here, we show that C. elegans GLR glial cells regulate axon specification of their nearby GABAergic RME neurons through GLR-RME gap junctions. Disruption of GLR-RME gap junctions causes misaccumulation of axonal markers in non-axonal neurites of RME neurons and converts microtubules in those neurites to form an axon-like assembly. We further uncover that GLR-RME gap junctions regulate RME axon specification through activation of the CDK-5 pathway in a calcium-dependent manner, involving a calpain clp-4. Therefore, our study reveals the function of glia-neuron gap junctions in neuronal axon specification and shows that calcium originated from glial cells can regulate neuronal intracellular pathways through gap junctions. DOI: http://dx.doi.org/10.7554/eLife.19510.001 PMID:27767956

  2. Octagonal Defects at Carbon Nanotube Junctions

    Directory of Open Access Journals (Sweden)

    W. Jaskólski

    2013-01-01

    Full Text Available We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (EF. The reconstructed junction has only one state near EF, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system.

  3. Fabrication of high quality ferromagnetic Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M. [Institute for Solid State Research, Research Centre Juelich, D-52425 Juelich (Germany) and CNI-Center of Nanoelectronic Systems for Information Technology, Research Centre Juelich, D-52425 Juelich (Germany)]. E-mail: m.weides@fz-juelich.de; Tillmann, K. [Institute for Solid State Research, Research Centre Juelich, D-52425 Juelich (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich, D-52425 Juelich (Germany); Kohlstedt, H. [Institute for Solid State Research, Research Centre Juelich, D-52425 Juelich (Germany); CNI-Center of Nanoelectronic Systems for Information Technology, Research Centre Juelich, D-52425 Juelich (Germany); Department of Material Science and Engineering and Department of Physics, University of Berkeley, CA 94720 (United States)

    2006-05-15

    We present ferromagnetic Nb/Al{sub 2}O{sub 3}/Ni{sub 60}Cu{sub 40}/Nb Josephson junctions (SIFS) with an ultrathin Al{sub 2}O{sub 3} tunnel barrier. The junction fabrication was optimized regarding junction insulation and homogeneity of current transport. Using ion-beam-etching and anodic oxidation we defined and insulated the junction mesas. The additional 2 nm thin Cu-layer below the ferromagnetic NiCu (SINFS) lowered interface roughness and ensured very homogeneous current transport. A high yield of junctional devices with j {sub c} spreads less than 2% was obtained.

  4. Ephrin-Bs Drive Junctional Downregulation and Actin Stress Fiber Disassembly to Enable Wound Re-epithelialization

    Directory of Open Access Journals (Sweden)

    Robert Nunan

    2015-11-01

    Full Text Available For a skin wound to successfully heal, the cut epidermal-edge cells have to migrate forward at the interface between scab and healthy granulation tissue. Much is known about how lead-edge cells migrate, but very little is known about the mechanisms that enable active participation by cells further back. Here we show that ephrin-B1 and its receptor EphB2 are both upregulated in vivo, just for the duration of repair, in the first 70 or so rows of epidermal cells, and this signal leads to downregulation of the molecular components of adherens and tight (but not desmosomal junctions, leading to loosening between neighbors and enabling shuffle room among epidermal cells. Additionally, this signaling leads to the shutdown of actomyosin stress fibers in these same epidermal cells, which may act to release tension within the wound monolayer. If this signaling axis is perturbed, then disrupted healing is a consequence in mouse and man.

  5. Seebeck effect in molecular junctions

    Science.gov (United States)

    Zimbovskaya, Natalya A.

    2016-05-01

    Advances in the fabrication and characterization of nanoscale systems presently allow for a better understanding of their thermoelectric properties. As is known, the building blocks of thermoelectricity are the Peltier and Seebeck effects. In the present work we review results of theoretical studies of the Seebeck effect in single-molecule junctions and similar systems. The behavior of thermovoltage and thermopower in these systems is controlled by several factors including the geometry of molecular bridges, the characteristics of contacts between the bridge and the electrodes, the strength of the Coulomb interactions between electrons on the bridge, and of electron-phonon interactions. We describe the impact of these factors on the thermopower. Also, we discuss a nonlinear Seebeck effect in molecular junctions.

  6. Electron transport in molecular junctions

    DEFF Research Database (Denmark)

    Jin, Chengjun

    This thesis addresses the electron transport in molecular junctions, focusing on the energy level alignment and correlation effects. Various levels of theory have been applied to study the structural and electronic effects in different molecular junctions, starting from the single particle density...... charge position are in quantitative agreement with the experiments, while pure DFT is not. This is the consequence of the accurate energy level alignment, where the DFT+∑ method corrects the self-interaction error in the standard DFT functional and uses a static image charge model to include the image...... charge effect on the energy level renormalization. Additionally, the gating of the 4,4’-bipyridine (44BP) molecule contacted to either Ni or Au electrodes has been investigated. Here it is found that the gating mechanism is conceptually different between two cases. In the case of Ni contacts where...

  7. How coherent are Josephson junctions?

    CERN Document Server

    Paik, Hanhee; Bishop, Lev S; Kirchmair, G; Catelani, G; Sears, A P; Johnson, B R; Reagor, M J; Frunzio, L; Glazman, L; Schoelkopf, R J

    2011-01-01

    Attaining sufficient coherence is a requirement for realizing a large-scale quantum computer. We present a new implementation of a superconducting transmon qubit that is strongly coupled to a three-dimensional superconducting cavity. We observe a reproducible increase in the coherence times of qubit (both $T_1$ and $T_2$ > 10 microseconds) and cavity ($T_{cav}$ ~ 50 microseconds) by more than an order of magnitude compared to the current state-of-art superconducting qubits. This enables the study of the stability and quality of Josephson junctions at precisions exceeding one part per million. Surprisingly, we see no evidence for $1/f$ critical current noise. At elevated temperatures, we observe the dissipation due to a small density (< 1 - 10 ppm) of thermally-excited quasiparticles. The results suggest that the overall quality of Josephson junctions will allow error rates of a few $10^{-4}$, approaching the error correction threshold.

  8. Morphogenesis of rat myotendinous junction.

    Science.gov (United States)

    Curzi, Davide; Ambrogini, Patrizia; Falcieri, Elisabetta; Burattini, Sabrina

    2013-10-01

    Myotendinous junction (MTJ) is the highly specialized complex which connects the skeletal muscle to the tendon for transmitting the contractile force between the two tissues. The purpose of this study was to investigate the MTJ development and rat EDL was chosen as a model. 1, 15, 30 day animals were considered and the junctions were analyzed by light and electron microscopy. The MTJ interface architecture increased during the development, extending the interaction between muscle and tendon. 1-day-old rats showed disorganized myofibril bundles, spread cytosol and incomplete rough endoplasmic reticulum, features partially improved in 15-day-old rats, and completely developed in 30-day-old animals. These findings indicate that muscle-tendon interface displays, during rat lifetime, numerically increased and longer tendon interdigitations, correlated with an improved organization of both tissues and with a progressive acquirement of full functionality.

  9. Thermoelectric efficiency of molecular junctions

    Science.gov (United States)

    Perroni, C. A.; Ninno, D.; Cataudella, V.

    2016-09-01

    Focus of the review is on experimental set-ups and theoretical proposals aimed to enhance thermoelectric performances of molecular junctions. In addition to charge conductance, the thermoelectric parameter commonly measured in these systems is the thermopower, which is typically rather low. We review recent experimental outcomes relative to several junction configurations used to optimize the thermopower. On the other hand, theoretical calculations provide estimations of all the thermoelectric parameters in the linear and non-linear regime, in particular of the thermoelectric figure of merit and efficiency, completing our knowledge of molecular thermoelectricity. For this reason, the review will mainly focus on theoretical studies analyzing the role of not only electronic, but also of the vibrational degrees of freedom. Theoretical results about thermoelectric phenomena in the coherent regime are reviewed focusing on interference effects which play a significant role in enhancing the figure of merit. Moreover, we review theoretical studies including the effects of molecular many-body interactions, such as electron-vibration couplings, which typically tend to reduce the efficiency. Since a fine tuning of many parameters and coupling strengths is required to optimize the thermoelectric conversion in molecular junctions, new theoretically proposed set-ups are discussed in the conclusions.

  10. Chaos induced by coupling between Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Azemtsa-Donfack, H.; Botha, A. E.

    2015-02-01

    It is found that, in a stack of intrinsic Josephson junctions in layered high temperature superconductors under external electromagnetic radiation, the chaotic features are triggered by interjunction coupling, i.e., the coupling between different junctions in the stack. While the radiation is well known to produce chaotic effects in the single junction, the effect of interjunction coupling is fundamentally different and it can lead to the onset of chaos via a different route to that of the single junction. A precise numerical study of the phase dynamics of intrinsic Josephson junctions, as described by the CCJJ+DC model, is performed. We demonstrate the charging of superconducting layers, in a bias current interval corresponding to a Shapiro step subharmonic, due to the creation of a longitudinal plasma wave along the stack of junctions. With increase in radiation amplitude chaotic behavior sets in. The chaotic features of the coupled Josephson junctions are analyzed by calculations of the Lyapunov exponents. We compare results for a stack of junctions to the case of a single junction and prove that the observed chaos is induced by the coupling between the junctions. The use of Shapiro step subharmonics may allow longitudinal plasma waves to be excited at low radiation power.

  11. Cell membrane and cell junctions in differentiation of preimplanted mouse embryos.

    Science.gov (United States)

    Izquierdo, L; Fernández, S; López, T

    1976-12-01

    Cell membrane and cell junctions in differentiation of preimplanted mouse embryos, (membrana celular y uniones celulares en la diferenciación del embrión de ratón antes de la implantación). Arch. Biol. Med. Exper. 10: 130-134, 1976. The development of cell junctions that seal the peripheral blastomeres could be a decisive step in the differentiation of morulae into blastocysts. The appearance of these junctions is studied by electron microscopy of late morulae and initial blastocysts. Zonulae occludentes as well as impermeability to lanthanum emulsion precedes the appearance of the blastocel and hence might be considered as one of its necessary causes.

  12. [Remodeling of cardiac gap junctions and arrhythmias].

    Science.gov (United States)

    Yu, Zhi-Bin; Sheng, Juan-Juan

    2011-12-25

    In the heart, gap junctions mediate electrical and chemical coupling between adjacent cardiomyocytes, forming the cell-to-cell pathways for orderly spread of the wave of electrical excitation responsible for a functional syncytium. Three principal connexins are expressed in cardiomyocytes, connexin 43 (CX43), CX40, and CX45. CX43 predominates in ventricular muscle cells. Most of the gap junctions, assembled from CX43, are located at the intercalated discs, often with larger junctional plaques at the disc periphery. The gap junctions are rarely distributed to the sides of the cardiomyocyte. The ischemia-reperfusion, cardiac hypertrophy, heart failure, hypercholesterolemia, and diabetes mellitus induce gap junction remodeling. The gap junction remodeling induced by above-mentioned diseases shows similar characteristics, including down-regulation of CX43, reduction in gap junction plaque size, increased heterogeneity and lateralization of gap junction distribution, and dephosphorylation of CX43. The elevated angiotensin II concentration in local myocardium may play an important role in the gap junction remodeling. The down-regulation of CX43 and lateralization of gap junction distribution alter anisotropic spread of the impulse of ventricular myocardium. The dephosphorylation of CX43 not only reduces electrical conductance, but also decreases permeability of chemicals between cardiomyocytes. The lateralization of gap junctions may increase the number of hemichannels formed by CX43. The opening of hemichannels induces ATP efflux and Na(+) influx, which forms a delayed after-depolarization. The gap junction remodeling in pathological condition produces arrhythmia substrate in the ventricles. In this review, the current knowledge on the relationship between the remodeling of cardiac gap junctions and arrhythmias were summarized.

  13. Involvement of YAP, TAZ and HSP90 in contact guidance and intercellular junction formation in corneal epithelial cells.

    Directory of Open Access Journals (Sweden)

    Vijay Krishna Raghunathan

    Full Text Available The extracellular environment possesses a rich milieu of biophysical and biochemical signaling cues that are simultaneously integrated by cells and influence cellular phenotype. Yes-associated protein (YAP and transcriptional co-activator with PDZ-binding motif (WWTR1; TAZ, two important signaling molecules of the Hippo pathway, have been recently implicated as nuclear relays of cytoskeletal changes mediated by substratum rigidity and topography. These proteins intersect with other important intracellular signaling pathways (e.g. Wnt and TGFβ. In the cornea, epithelial cells adhere to the stroma through a 3-dimensional topography-rich basement membrane, with features in the nano-submicron size-scale that are capable of profoundly modulating a wide range of fundamental cell behaviors. The influences of substratum-topography, YAP/TAZ knockdown, and HSP90 inhibition on cell morphology, YAP/TAZ localization, and the expression of TGFβ2 and CTGF, were investigated. The results demonstrate (a that knockdown of TAZ enhances contact guidance in a YAP dependent manner, (b that CTGF is predominantly regulated by YAP and not TAZ, and (c that TGFβ2 is regulated by both YAP and TAZ in these cells. Additionally, inhibition of HSP90 resulted in nuclear localization and subsequent transcriptional-activation of YAP, formation of cell-cell junctions and co-localization of E-cadherin and β-catenin at adherens junctions. Results presented in this study reflect the complexities underlying the molecular relationships between the cytoskeleton, growth factors, heat shock proteins, and co-activators of transcription that impact mechanotransduction. The data reveal the importance of YAP/TAZ on the cell behaviors, and gene and protein expression.

  14. Incompressible Turbulent Wing-Body Junction Flow

    Science.gov (United States)

    Krishnamurthy, R.; Cagle, Corey D.; Chandra, S.

    1998-01-01

    The overall objective of this study is to contribute to the optimized design of fan bypass systems in advanced turbofan engines. Increasing the engine bypass ratios have provided a major boost in engine performance improvement over the last fifty years. An engine with high bypass ratio (11-16:1) such as the Advanced Ducted Propulsion (ADP) is being developed and is expected to provide an additional 25% improvement in overall efficiency over the early turbofans. Such significant improvements in overall efficiency would reduce the cost per seat mile, which is a major government and Industry challenge for the 21th century. The research is part of the Advanced Subsonic Technology (AST) program that involves a NASA, U.S. Industry and FAA partnership with the goal of a safe and highly productive global air transportation system. The immediate objective of the study is to perform numerical simulation of duct-strut interactions to elucidate the loss mechanisms associated with this configuration that is typical of advanced turbofan engines such as ADP. However, at present experimental data for a duct-strut configuration are not available. Thus, as a first step a wing-body junction flow would be studied and is the specific objective of the present study. At the outset it is to be recognized that while duct-strut interaction flow is similar to that of wing-body junction flows, there are some differences owing to the presence of a wall at both ends of the strut. Likewise, some differences are due to the sheared inflow (as opposed to a uniform inflow) velocity profile. It is however expected that some features of a wing-body junction flow would persist. Next, some of the salient aspects of the complex flow near a wing-body junction, as revealed by various studies reported in the literature will be reviewed. One of the principle characteristics of the juncture flow, is the presence of the mean flow components in a plane perpendicular to the direction of the oncoming free

  15. Experimental investigation of high cycle thermal fatigue in a T-junction piping system

    Energy Technology Data Exchange (ETDEWEB)

    Selvam, P. Karthick; Kulenovic, Rudi; Laurien, Eckart [Stuttgart Univ. (Germany). Inst. of Nuclear Technology and Energy Systems (IKE)

    2015-10-15

    High cycle thermal fatigue damage of structure in the vicinity of T-junction piping systems in nuclear power plants is of importance. Mixing of coolant streams at significant temperature differences causes thermal fluctuations near piping wall leading to gradual thermal degradation. Flow mixing in a T-junction is performed. The determined factors result in bending stresses being imposed on the piping system ('Banana effect').

  16. Physics and Applications of NIS Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Ullom, J N

    2001-08-24

    This paper reviews the physics and applications of Normal-Insulator-Superconductor (NIS) tunnel junctions. The current-voltage properties of NIS junctions are diode-like with a strong temperature dependence. Hence, these structures can be used as sensitive thermometers at temperatures well below the energy gap, {Delta}, of the superconducting electrode. For junction voltages comparable to {Delta}/q, current flow removes energy from the normal electrode. This property has been exploited to build refrigerators capable of cooling thin-film circuits from 0.3 K to 0.1 K. Calorimeters and bolometers for the detection of X-rays and millimeter-wave radiation, respectively, have successfully been built from NIS junctions. NIS junctions have also been used to probe the superconducting state. Finally, recent ideas for the use of NIS junctions as simple circuit elements are described.

  17. Algorithms for Junctions in Directed Acyclic Graphs

    CERN Document Server

    Ferreira, Carlos Eduardo

    2012-01-01

    Given a pair of distinct vertices u, v in a graph G, we say that s is a junction of u, v if there are in G internally vertex disjoint directed paths from s to u and from s to v. We show how to characterize junctions in directed acyclic graphs. We also consider the two problems in the following and derive efficient algorithms to solve them. Given a directed acyclic graph G and a vertex s in G, how can we find all pairs of vertices of G such that s is a junction of them? And given a directed acyclic graph G and k pairs of vertices of G, how can we preprocess G such that all junctions of k given pairs of vertices could be listed quickly? All junctions of k pairs problem arises in an application in Anthropology and we apply our algorithm to find such junctions on kinship networks of some brazilian indian ethnic groups.

  18. Molecular junctions: can pulling influence optical controllability?

    Science.gov (United States)

    Parker, Shane M; Smeu, Manuel; Franco, Ignacio; Ratner, Mark A; Seideman, Tamar

    2014-08-13

    We suggest the combination of single molecule pulling and optical control as a way to enhance control over the electron transport characteristics of a molecular junction. We demonstrate using a model junction consisting of biphenyl-dithiol coupled to gold contacts. The junction is pulled while optically manipulating the dihedral angle between the two rings. Quantum dynamics simulations show that molecular pulling enhances the degree of control over the dihedral angle and hence over the transport properties.

  19. Loss models for long Josephson junctions

    DEFF Research Database (Denmark)

    Olsen, O. H.; Samuelsen, Mogens Rugholm

    1984-01-01

    A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement.......A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement....

  20. Gap junction disorders of myelinating cells.

    Science.gov (United States)

    Kleopa, Kleopas A; Orthmann-Murphy, Jennifer; Sargiannidou, Irene

    2010-01-01

    Gap junctions (GJs) are channels that allow the diffusion of ions and small molecules across apposed cell membranes. In peripheral nerves, Schwann cells express the GJ proteins connexin32 (Cx32) and Cx29, which have distinct localizations. Cx32 forms GJs through non-compact myelin areas, whereas Cx29 forms hemichannels in the innermost layers of myelin apposing axonal Shaker-type K+ channels. In the CNS, rodent oligodendrocytes express Cx47, Cx32 and Cx29. Cx47 is expressed by all types of oligodendrocytes both in the white and grey matter and forms GJs on cell bodies and proximal processes, as well as most of the intercellular channels with astrocytes. Cx32 is expressed mostly by white matter oligodendrocytes and is localized in the myelin sheath of large diameter fibers. Cx29, and its human ortholog Cx31.3, appear to be restricted to oligodendrocytes that myelinate small caliber fibers, likely forming hemichannels. The importance of intercellular and intracellular GJs in myelinating cells are demonstrated by human disorders resulting from mutations affecting GJ proteins. The X-linked Charcot Marie Tooth disease (CMT1X) is caused by hundreds of mutations affecting Cx32. Patients with CMT1X present mainly with a progressive peripheral neuropathy, which may be accompanied by CNS myelin dysfunction. Mutations in Cx47 may cause a devastating leukodystrophy called Pelizaeus-Merzbacher-like disease or a milder spastic paraplegia. In addition, CNS demyelination may be caused by defects in genes expressing astrocytic GJ proteins, which are essential for oligodendrocytes. Findings from in vitro and in vivo models of these disorders developed over the last decade indicate that most mutations cause loss of function and an inability of the mutant connexins to form functional GJs. Here we review the clinical, genetic, and neurobiological aspects of GJ disorders affecting the PNS and CNS myelinating cells.

  1. Electromechanical resistive switching via back-to-back Schottky junctions

    Directory of Open Access Journals (Sweden)

    Lijie Li

    2015-09-01

    Full Text Available The physics of the electromechanical resistive switching is uncovered using the theory of back-to-back Schottky junctions combined with the quantum domain space charge transport. A theoretical model of the basic element of resistive switching devices realized by the metal-ZnO nanowires-metal structure has been created and analyzed. Simulation results show that the reverse biased Schottky junction and the air gap impedance dominate the current-voltage relation at higher external voltages; thereby electromechanically varying the air gap thickness causes the device exhibit resistive tuning characteristics. As the device dimension is in nanometre scale, investigation of the model based on quantum mechanics has also been conducted.

  2. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  3. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

  4. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  5. Shot noise in YBCO bicrystal Josephson junctions

    DEFF Research Database (Denmark)

    Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.;

    2003-01-01

    We measured spectral noise density in YBCO symmetric bicrystal Josephson junctions on sapphire substrates at bias voltages up to 100 mV and T 4.2 K. Normal state resistance of the Josephson junctions, R-N = 20-90 Omega and ICRN up to 2.2 mV have been observed in the experimental samples. Noise...

  6. Excimer laser annealing: A gold process for CZ silicon junction formation

    Science.gov (United States)

    Wong, David C.; Bottenberg, William R.; Byron, Stanley; Alexander, Paul

    A cold process using an excimer laser for junction formation in silicon has been evaluated as a way to avoid problems associated with thermal diffusion. Conventional thermal diffusion can cause bulk precipitation of SiOx and SiC or fail to completely activate the dopant, leaving a degenerate layer at the surface. Experiments were conducted to determine the feasibility of fabricating high quality p-n junctions using a pulsed excimer laser for junction formation at remelt temperature with ion-implanted surfaces. Solar-cell efficiency exceeding 16 percent was obtained using Czochralski single-crystal silicon without benefit of back surface field or surface passivation. Characterization shows that the formation of uniform, shallow junctions (approximately 0.25 micron) by excimer laser scanning preserves the minority carrier lifetime that leads to high current collection. However, the process is sensitive to initial surface conditions and handling parameters that drive the cost up.

  7. Shear zone junctions: Of zippers and freeways

    Science.gov (United States)

    Passchier, Cees W.; Platt, John P.

    2017-02-01

    Ductile shear zones are commonly treated as straight high-strain domains with uniform shear sense and characteristic curved foliation trails, bounded by non-deforming wall rock. Many shear zones, however, are branched, and if movement on such branches is contemporaneous, the resulting shape can be complicated and lead to unusual shear sense arrangement and foliation geometries in the wall rock. For Y-shaped shear zone triple junctions with three joining branches and transport direction at a high angle to the branchline, only eight basic types of junction are thought to be stable and to produce significant displacement. The simplest type, called freeway junctions, have similar shear sense in all three branches. The other types show joining or separating behaviour of shear zone branches similar to the action of a zipper. Such junctions may have shear zone branches that join to form a single branch (closing zipper junction), or a single shear zone that splits to form two branches, (opening zipper junction). All categories of shear zone junctions show characteristic foliation patterns and deflection of markers in the wall rock. Closing zipper junctions are unusual, since they form a non-active zone with opposite deflection of foliations in the wall rock known as an extraction fault or wake. Shear zipper junctions can form domains of overprinting shear sense along their flanks. A small and large field example are given from NE Spain and Eastern Anatolia. The geometry of more complex, 3D shear zone junctions with slip parallel and oblique to the branchline is briefly discussed.

  8. Distribution of the feline calicivirus receptor junctional adhesion molecule a in feline tissues.

    Science.gov (United States)

    Pesavento, P A; Stokol, T; Liu, H; van der List, D A; Gaffney, P M; Parker, J S

    2011-03-01

    Junctional adhesion molecule A (JAM-A) is an immunoglobulin superfamily protein that plays an important role in the assembly and maintenance of tight junctions and the establishment of epithelial cell polarity. The feline JAM-A (fJAM-A) is a functional receptor for feline calicivirus (FCV). Among natural diseases associated with FCV infection, isolates that cause oral vesicular disease are detected in epithelial cells; however, isolates that cause systemic disease are detected in multiple cell types. The distribution of an FCV receptor or receptors in feline tissues is relevant to viral pathogenesis in that it should reflect the wide latitude of clinical sequelae associated with FCV infection. The authors examined the expression of feline JAM-A in the cat by using confocal immunofluorescence localization on normal tissues, with special regard to tissue targets of naturally occurring FCV. As described in the human and the mouse, fJAM-A was widely distributed in feline tissues, where it localized at cell-cell junctions of epithelial and endothelial cells. fJAM-A was highly expressed on feline platelets, with lower levels of expression on feline peripheral blood leukocytes. Additionally, FCV infection of a feline epithelial cell monolayer causes redistribution of fJAM-A to the cytosol of infected cells. It is reasonable to propose that the spectrum of lesions caused by FCV reflects disruption of intercellular junctions that rely on fJAM-A function and tight junctional integrity.

  9. Coordinate transformation in the model of long Josephson junctions: geometrically equivalent Josephson junctions

    Science.gov (United States)

    Semerdzhieva, E. G.; Boyadzhiev, T. L.; Shukrinov, Yu. M.

    2005-10-01

    The transition from the model of a long Josephson junction of variable width to the model of a junction with a coordinate-dependent Josephson current amplitude is effected through a coordinate transformation. This establishes the correspondence between the classes of Josephson junctions of variable width and quasi-one-dimensional junctions with a variable thickness of the barrier layer. It is shown that for a junction of exponentially varying width the barrier layer of the equivalent quasi-one-dimensional junction has a distributed resistive inhomogeneity that acts as an attractor for magnetic flux vortices. The curve of the critical current versus magnetic field for a Josephson junction with a resistive microinhomogeneity is constructed with the aid of a numerical simulation, and a comparison is made with the critical curve of a junction of exponentially varying width. The possibility of replacing a distributed inhomogeneity in a Josephson junction by a local inhomogeneity at the end of the junction is thereby demonstrated; this can have certain advantages from a technological point of view.

  10. Atomically Abrupt Topological p-n Junction.

    Science.gov (United States)

    Kim, Sung Hwan; Jin, Kyung-Hwan; Kho, Byung Woo; Park, Byeong-Gyu; Liu, Feng; Kim, Jun Sung; Yeom, Han Woong

    2017-08-24

    Topological insulators (TI's) are a new class of quantum matter with extraordinary surface electronic states, which bear great potential for spintronics and error-tolerant quantum computing. In order to put a TI into any practical use, these materials need to be fabricated into devices whose basic units are often p-n junctions. Interesting electronic properties of a 'topological' p-n junction were proposed theoretically such as the junction electronic state and the spin rectification. However, the fabrication of a lateral topological p-n junction has been challenging because of materials, process, and fundamental reasons. Here, we demonstrate an innovative approach to realize a p-n junction of topological surface states (TSS's) of a three-dimensional (3D) topological insulator (TI) with an atomically abrupt interface. When a ultrathin Sb film is grown on a 3D TI of Bi2Se3 with a typical n-type TSS, the surface develops a strongly p-type TSS through the substantial hybridization between the 2D Sb film and the Bi2Se3 surface. Thus, the Bi2Se3 surface covered partially with Sb films bifurcates into areas of n- and p-type TSS's as separated by atomic step edges with a lateral electronic junction of as short as 2 nm. This approach opens a different avenue toward various electronic and spintronic devices based on well-defined topological p-n junctions with the scalability down to atomic dimensions.

  11. Bioengineering a Single-Protein Junction.

    Science.gov (United States)

    Ruiz, Marta P; Aragones, Albert C; Camarero, Nuria; Vilhena, J G; Ortega, Maria; Zotti, Linda Angela; Perez, Ruben; Cuevas, Juan Carlos; Gorostiza, Pau; Díez-Pérez, Ismael

    2017-10-05

    Bioelectronics moves towards designing nanoscale electronic platforms that allow in vivo determinations. Such devices require interfacing complex biomolecular moieties as the sensing units to an electronic platform for signal transduction. Inevitably, a systematic design goes through a bottom-up understanding of the structurally related electrical signatures of the biomolecular circuit, which will ultimately lead us to tailor its electrical properties. Toward this aim, we show here the first example of bioengineered charge transport in a single-protein electrical contact. The results reveal that a single point-site mutation at the docking hydrophobic patch of a Cu-Azurin causes minor structural distortion of the protein blue Cu site and a dramatic change in the charge transport regime of the single-protein contact, which goes from the classical Cu-mediated 2-step transport in this system to a direct coherent tunneling. Our extensive spectroscopic studies and molecular-dynamics simulations show that the proteins' folding structures are preserved in the single-protein junction. The DFT-computed frontier orbital of the relevant protein segments suggests that the Cu center participation in each protein variant accounts for the different observed charge transport behavior. This work is a direct evidence of charge transport control in a protein backbone through external mutagenesis and a unique nanoscale platform to study structurally related biological electron transfer.

  12. A model for the CdTe/CdS junction

    Energy Technology Data Exchange (ETDEWEB)

    Linam, David L; Singh, Vijay P; McClure, Jonh C; Lush, Gregory; Mathew, X [Centro de Investigacion en Energia, UNAM, Temixco, Morelos (Mexico)

    2000-07-01

    The saturation current and junction quality factor of a series of commercial CdTe/CdS solar cells have been measured. A high saturation current (compared to, for example, Si cells) is the primary cause of lower than theoretical efficiency. Furthermore, this current and the junction quality factor are functions of both light intensity and voltage bias level. It was found that tunneling is the predominant junction transport mechanism at high light levels and at low voltages while diffusion and regeneration/combination dominate at high voltage and low light levels. A model is presented to account for these observations. [Spanish] Se midieron las corrientes de saturacion y el factor de calidad de la union de una serie de celdas solares CdTe/CdS. Una corriente de saturacion alta (comparada por ejemplo a celdas de Si) es la causa primordial de eficiencia inferior a la teorica. Mas aun esta corriente y el factor de la calidad de la junta son funciones tanto de la intensidad de la luz y del nivel del voltaje de polarizacion. Se encontro que el paso a traves de una barrera de potencial (Tunneling) es el mecanismo de transporte predominate en la junta a altos niveles de luz y bajos voltajes mientras que la difusion y la regeneracion-combinacion predominaba a alto voltaje y bajos niveles de luz. Se presenta un modelo para tomar en cuenta estas observaciones.

  13. Microfluidic mixing in a Y-junction open channel

    Directory of Open Access Journals (Sweden)

    Jue Nee Tan

    2012-09-01

    Full Text Available In the laminar regimes typical of microfluidic systems’, mixing is governed by molecular diffusion; however this process is slow in nature. Consequently, passive or active methods are usually sought for effective mixing. In this work, open fluidic channels will be investigated; these channels are bounded on all but one face by an air/fluid interface. Firstly, it will be shown that flow in open channels can merge at a Y-junction in a stable manner; hence two fluids can be brought into contact with each other. Secondly, the mixing of these two fluids will be studied. At high flow rates (>300 μl/min mixing occurs at the junction without need for additional intervention, this mixing is far swifter than can be expected from molecular diffusion. At lower flow rates, intervention is required. A major motivation for open fluidic channels is the ability to interact with the surrounding air environment; this feature is used to effect the desired mixing. It is shown that by blowing an air jet across the junction, shear stresses at the air/fluid interface causes a flow profile within the fluid inductive to rapid mixing of the fluids.

  14. Fluxon dynamics in three stacked Josephson junctions

    DEFF Research Database (Denmark)

    Gorria, Carlos; Christiansen, Peter Leth; Gaididei, Yuri Borisovich

    2002-01-01

    /sub -/, the coupling between junctions leads to a repulsion of the fluxons with the same polarity. Above this critical velocity a fluxon will induce radiation in the neighboring junctions, leading to a bunching of the fluxons in the stacked junctions. Using the Sakai-Bodin-Pedersen model, three coupled perturbed sine......-Gordon equations are numerically studied for different values of coupling, damping, and bias parameters. In a narrow range of velocities bunching occurs. Outside this interval the fluxons split and new fluxons may be created. I-V characteristics are presented...

  15. Temperature dependence of thermopower in molecular junctions

    Science.gov (United States)

    Kim, Youngsang; Lenert, Andrej; Meyhofer, Edgar; Reddy, Pramod

    2016-07-01

    The thermoelectric properties of molecular junctions are of considerable interest due to their promise for efficient energy conversion. While the dependence of thermoelectric properties of junctions on molecular structure has been recently studied, their temperature dependence remains unexplored. Using a custom built variable temperature scanning tunneling microscope, we measured the thermopower and electrical conductance of individual benzenedithiol junctions over a range of temperatures (100 K-300 K). We find that while the electrical conductance is independent of temperature, the thermopower increases linearly with temperature, confirming the predictions of the Landauer theory.

  16. Phase qubits fabricated with trilayer junctions

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M; Bialczak, R C; Lenander, M; Lucero, E; Mariantoni, Matteo; Neeley, M; O' Connell, A D; Sank, D; Wang, H; Wenner, J; Yamamoto, T; Yin, Y; Cleland, A N; Martinis, J, E-mail: martin.weides@nist.gov, E-mail: martinis@physics.ucsb.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

    2011-05-15

    We have developed a novel Josephson junction geometry with minimal volume of lossy isolation dielectric, suitable for higher quality trilayer junctions implemented in qubits. The junctions are based on in situ deposited trilayers with thermal tunnel oxide, have micron-sized areas and a low subgap current. In qubit spectroscopy only a few avoided level crossings are observed, and the measured relaxation time of T{sub 1{approx}}400 ns is in good agreement with the usual phase qubit decay time, indicating low loss due to the additional isolation dielectric.

  17. Cell-cell junctions: a target of acoustic overstimulation in the sensory epithelium of the cochlea

    Directory of Open Access Journals (Sweden)

    Zheng Guiliang

    2012-06-01

    Full Text Available Abstract Background Exposure to intense noise causes the excessive movement of the organ of Corti, stretching the organ and compromising sensory cell functions. We recently revealed changes in the transcriptional expression of multiple adhesion-related genes during the acute phases of cochlear damage, suggesting that the disruption of cell-cell junctions is an early event in the process of cochlear pathogenesis. However, the functional state of cell junctions in the sensory epithelium is not clear. Here, we employed graded dextran-FITC, a macromolecule tracer that is impermeable to the organ of Corti under physiological conditions, to evaluate the barrier function of cell junctions in normal and noise-traumatized cochlear sensory epithelia. Results Exposure to an impulse noise of 155 dB (peak sound pressure level caused a site-specific disruption in the intercellular junctions within the sensory epithelium of the chinchilla cochlea. The most vulnerable sites were the junctions among the Hensen cells and between the Hensen and Deiters cells within the outer zone of the sensory epithelium. The junction clefts that formed in the reticular lamina were permeable to 40 and 500 but not 2,000 kDa dextran-FITC macromolecules. Moreover, this study showed that the interruption of junction integrity occurred in the reticular lamina and also in the basilar membrane, a site that had been considered to be resistant to acoustic injury. Finally, our study revealed a general spatial correlation between the site of sensory cell damage and the site of junction disruption. However, the two events lacked a strict one-to-one correlation, suggesting that the disruption of cell-cell junctions is a contributing, but not the sole, factor for initiating acute sensory cell death. Conclusions Impulse noise causes the functional disruption of intercellular junctions in the sensory epithelium of the chinchilla cochlea. This disruption occurs at an early phase of cochlear

  18. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions.

    Science.gov (United States)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin; Kjølbye, Anne-Louise; Hennan, James K; Holstein-Rathlou, Niels-Henrik; Petersen, Jørgen Søberg; Nielsen, Morten Schak

    2007-03-01

    Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes. In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs and by interfering with the gating of gap junctional channels.

  19. Gap junction remodeling and cardiac arrhythmogenesis in a murine model of oculodentodigital dysplasia.

    Science.gov (United States)

    Kalcheva, Nellie; Qu, Jiaxiang; Sandeep, Nefthi; Garcia, Luis; Zhang, Jie; Wang, Zhiyong; Lampe, Paul D; Suadicani, Sylvia O; Spray, David C; Fishman, Glenn I

    2007-12-18

    Gap junction channels are required for normal cardiac impulse propagation, and gap junction remodeling is associated with enhanced arrhythmic risk. Oculodentodigital dysplasia (ODDD) is a multisystem syndrome due to mutations in the connexin43 (Cx43) gap junction channel gene. To determine the effects of a human connexin channelopathy on cardiac electrophysiology and arrhythmogenesis, we generated a murine model of ODDD by introducing the disease-causing I130T mutant allele into the mouse genome. Cx43 abundance was markedly reduced in mutant hearts with preferential loss of phosphorylated forms that interfered with trafficking and assembly of gap junctions in the junctional membrane. Dual whole-cell patch-clamp studies showed significantly lower junctional conductance between neonatal cell pairs from mutant hearts, and optical mapping of isolated-perfused hearts with voltage-sensitive dyes demonstrated significant slowing of conduction velocity. Programmed electrical stimulation revealed a markedly increased susceptibility to spontaneous and inducible ventricular tachyarrhythmias. In summary, our data demonstrate that the I130T mutation interferes with Cx43 posttranslational processing, resulting in diminished cell-cell coupling, slowing of impulse propagation, and a proarrhythmic substrate.

  20. Pharmacology of gap junctions. New pharmacological targets for treatment of arrhythmia, seizure and cancer?

    Science.gov (United States)

    Salameh, Aida; Dhein, Stefan

    2005-12-20

    Intercellular communication in many organs is maintained via intercellular gap junction channels composed of connexins, a large protein family with a number of isoforms. This gap junction intercellular communication (GJIC) allows the propagation of action potentials (e.g., in brain, heart), and the transfer of small molecules which may regulate cell growth, differentiation and function. The latter has been shown to be involved in cancer growth: reduced GJIC often is associated with increased tumor growth or with de-differentiation processes. Disturbances of GJIC in the heart can cause arrhythmia, while in brain electrical activity during seizures seems to be propagated via gap junction channels. Many diseases or pathophysiological conditions seem to be associated with alterations of gap junction protein expression. Thus, depending on the target disease opening or closure of gap junctions may be of interest, or alteration of connexin expression. GJIC can be affected acutely by changing gap junction conductance or--more chronic--by altering connexin expression and membrane localisation. This review gives an overview on drugs affecting GJIC.

  1. Presynaptic spike broadening reduces junctional potential amplitude.

    Science.gov (United States)

    Spencer, A N; Przysiezniak, J; Acosta-Urquidi, J; Basarsky, T A

    1989-08-24

    Presynaptic modulation of action potential duration may regulate synaptic transmission in both vertebrates and invertebrates. Such synaptic plasticity is brought about by modifications to membrane currents at presynaptic release sites, which, in turn, lead to changes in the concentration of cytosolic calcium available for mediating transmitter release. The 'primitive' neuromuscular junction of the jellyfish Polyorchis penicillatus is a useful model of presynaptic modulation. In this study, we show that the durations of action potentials in the motor neurons of this jellyfish are negatively correlated with the amplitude of excitatory junctional potentials. We present data from in vitro voltage-clamp experiments showing that short duration voltage spikes, which elicit large excitatory junctional potentials in vivo, produce larger and briefer calcium currents than do long duration action potentials, which elicit small excitatory junctional potentials.

  2. Laparoscopically assisted pyeloplasty for ureteropelvic junction ...

    African Journals Online (AJOL)

    junction obstruction: a transperitoneal versus a retroperitoneal approach ... laparoscopic-assisted dismembered pyeloplasty (TLADP) ... to an open technique for two patients of the TLADP group; ... Annals of Pediatric Surgery 2012, 8:29–31.

  3. Tight Junctions in Salivary Epithelium

    Directory of Open Access Journals (Sweden)

    Olga J. Baker

    2010-01-01

    Full Text Available Epithelial cell tight junctions (TJs consist of a narrow belt-like structure in the apical region of the lateral plasma membrane that circumferentially binds each cell to its neighbor. TJs are found in tissues that are involved in polarized secretions, absorption functions, and maintaining barriers between blood and interstitial fluids. The morphology, permeability, and ion selectivity of TJ vary among different types of tissues and species. TJs are very dynamic structures that assemble, grow, reorganize, and disassemble during physiological or pathological events. Several studies have indicated the active role of TJ in intestinal, renal, and airway epithelial function; however, the functional significance of TJ in salivary gland epithelium is poorly understood. Interactions between different combinations of the TJ family (each with their own unique regulatory proteins define tissue specificity and functions during physiopathological processes; however, these interaction patterns have not been studied in salivary glands. The purpose of this review is to analyze some of the current data regarding the regulatory components of the TJ that could potentially affect cellular functions of the salivary epithelium.

  4. Androgen-Dependent Sertoli Cell Tight Junction Remodeling Is Mediated by Multiple Tight Junction Components

    National Research Council Canada - National Science Library

    Chakraborty, Papia; William Buaas, F; Sharma, Manju; Smith, Benjamin E; Greenlee, Anne R; Eacker, Stephen M; Braun, Robert E

    2014-01-01

    Sertoli cell tight junctions (SCTJs) of the seminiferous epithelium create a specialized microenvironment in the testis to aid differentiation of spermatocytes and spermatids from spermatogonial stem cells...

  5. Junction Plasmon-Induced Molecular Reorientation

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Hu, Dehong; Hess, Wayne P.

    2013-10-17

    Time and frequency dependent intensity variations in sequences of Raman spectra recorded at plasmonic junctions can be assigned to molecular reorientation. This is revealed through Raman trajectories recorded at a nanojunction formed between a silver AFM tip and a corrugated silver surface coated with biphenyl-4,4’-dithiol. Molecular motion is not observed when the tip is retracted and only surface enhancement is operative. In effect, junction plasmon induced molecular reorientation is tracked.

  6. [Clinical anatomy of the esophagogastric junction].

    Science.gov (United States)

    Tănase, M; Aldea, A S

    2012-01-01

    The esophagogastric junction is a controversial anatomical area, due to its sphincteric mechanism which does not show an obvious anatomical basis. The aim of this study is to investigate the anatomical components that endoscopically indicate the mucosal esophagogastric junction in hiatal hernia patients. The esophagogastric junction was investigated in 27 hiatal hernia patients undergoing surgery. Hiatal hernia is an extension of the stomach situated between the esophagogastric junction and the diaphragmatic indentation. The following types of hiatal hernia were found: sliding hiatal hernia (type I) in 4 patients (14.81%), rolling hiatal hernia (type II) in 2 (7.4%), mixed hiatal hernia (type III) in 12 (44.44%), type IV hiatal hernia in 4 (14.81%) and recurrent hiatal hernia in 5 (18.51%). Of the 27 hiatal hernia patients, 8 (29.6%) were operated using classical procedures: laparotomy--6 (75%) and laparoscopic surgery--2 (25%). The angle of His cannot be used for marking the mucosal esophagogastric junction due to the severe damage of the lower esophageal sphincter in hiatal hernia patients. The squamocolumnar junction is displaced in hiatal hernia patients and was not an option for the study group. The distal end of the esophageal longitudinal palisading vessels needs medication (proton pump inhibitors that reduce the gastric acid production), in order to enhance the visibility of these vessels. The proximal end of gastric longitudinal mucosal folds proved to be the most reliable site to identify endoscopically the mucosal esophagogastric junction. The anatomical structure of the esophagogastric junction differs in hiatal hernia patients and these peculiarities are very important in surgery.

  7. The Dissolution of Double Holliday Junctions

    DEFF Research Database (Denmark)

    Bizard, Anna H; Hickson, Ian D

    2014-01-01

    as "double Holliday junction dissolution." This reaction requires the cooperative action of a so-called "dissolvasome" comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding......) fold containing accessory factor (Rmi1). This review details our current knowledge of the dissolution process and the players involved in catalyzing this mechanistically complex means of completing homologous recombination reactions....

  8. Calcium Channels and Oxidative Stress Mediate a Synergistic Disruption of Tight Junctions by Ethanol and Acetaldehyde in Caco-2 Cell Monolayers.

    Science.gov (United States)

    Samak, Geetha; Gangwar, Ruchika; Meena, Avtar S; Rao, Roshan G; Shukla, Pradeep K; Manda, Bhargavi; Narayanan, Damodaran; Jaggar, Jonathan H; Rao, RadhaKrishna

    2016-12-13

    Ethanol is metabolized into acetaldehyde in most tissues. In this study, we investigated the synergistic effect of ethanol and acetaldehyde on the tight junction integrity in Caco-2 cell monolayers. Expression of alcohol dehydrogenase sensitized Caco-2 cells to ethanol-induced tight junction disruption and barrier dysfunction, whereas aldehyde dehydrogenase attenuated acetaldehyde-induced tight junction disruption. Ethanol up to 150 mM did not affect tight junction integrity or barrier function, but it dose-dependently increased acetaldehyde-mediated tight junction disruption and barrier dysfunction. Src kinase and MLCK inhibitors blocked this synergistic effect of ethanol and acetaldehyde on tight junction. Ethanol and acetaldehyde caused a rapid and synergistic elevation of intracellular calcium. Calcium depletion by BAPTA or Ca(2+)-free medium blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. Diltiazem and selective knockdown of TRPV6 or CaV1.3 channels, by shRNA blocked ethanol and acetaldehyde-induced tight junction disruption and barrier dysfunction. Ethanol and acetaldehyde induced a rapid and synergistic increase in reactive oxygen species by a calcium-dependent mechanism. N-acetyl-L-cysteine and cyclosporine A, blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. These results demonstrate that ethanol and acetaldehyde synergistically disrupt tight junctions by a mechanism involving calcium, oxidative stress, Src kinase and MLCK.

  9. Self-filtering oscillations in carbon nanotube hetero-junctions.

    Science.gov (United States)

    Scarpa, F; Narojczyk, J W; Wojciechowski, K W; Inman, D J

    2011-11-18

    We evaluate the vibrational properties of single-wall carbon nanotube (SWCNT) hetero-junction (HJ) oscillators using a hybrid atomistic-continuum approach validated by molecular mechanics/molecular dynamics simulations. The SWCNT-HJs show a broken symmetry topology of their mode shapes, with striction effects caused on the bending and radial modes by the combined effect of the HJ and the tube with the thinner radius. The single-wall nanotube HJs also show selective mass sensing properties based solely on the geometry and type of the boundary conditions of the specific nanostructure. This unusual behaviour has not been observed so far in classical SWCNT systems.

  10. Theories of subharmonic gap structures in superconducting junctions

    DEFF Research Database (Denmark)

    Hasselberg, L.E.; Levinsen, M. T.; Samuelsen, Mogens Rugholm

    1974-01-01

    The two theories of subharmonic gap structures in superconducting junctions, multiparticle tunneling and self-coupling due to an electromagnetic field set up by the ac Josephson current, are analyzed when microwaves are applied. Both theories give the same location in voltage for the microwave......-induced satellites and the same microwave-power dependence for the subharmonic gap structure and the satellites. Therefore other properties than these are to be considered in order to distinguish between the two theories. We suggest that self-coupling is the main cause of the subharmonic gap structure....

  11. Gap junctions: structure and function (Review).

    Science.gov (United States)

    Evans, W Howard; Martin, Patricia E M

    2002-01-01

    Gap junctions are plasma membrane spatial microdomains constructed of assemblies of channel proteins called connexins in vertebrates and innexins in invertebrates. The channels provide direct intercellular communication pathways allowing rapid exchange of ions and metabolites up to approximately 1 kD in size. Approximately 20 connexins are identified in the human or mouse genome, and orthologues are increasingly characterized in other vertebrates. Most cell types express multiple connexin isoforms, making likely the construction of a spectrum of heteromeric hemichannels and heterotypic gap junctions that could provide a structural basis for the charge and size selectivity of these intercellular channels. The precise nature of the potential signalling information traversing junctions in physiologically defined situations remains elusive, but extensive progress has been made in elucidating how connexins are assembled into gap junctions. Also, participation of gap junction hemichannels in the propagation of calcium waves via an extracellular purinergic pathway is emerging. Connexin mutations have been identified in a number of genetically inherited channel communication-opathies. These are detected in connexin 32 in Charcot Marie Tooth-X linked disease, in connexins 26 and 30 in deafness and skin diseases, and in connexins 46 and 50 in hereditary cataracts. Biochemical approaches indicate that many of the mutated connexins are mistargeted to gap junctions and/or fail to oligomerize correctly into hemichannels. Genetic ablation approaches are helping to map out a connexin code and point to specific connexins being required for cell growth and differentiation as well as underwriting basic intercellular communication.

  12. Predictive modelling of ferroelectric tunnel junctions

    Science.gov (United States)

    Velev, Julian P.; Burton, John D.; Zhuravlev, Mikhail Ye; Tsymbal, Evgeny Y.

    2016-05-01

    Ferroelectric tunnel junctions combine the phenomena of quantum-mechanical tunnelling and switchable spontaneous polarisation of a nanometre-thick ferroelectric film into novel device functionality. Switching the ferroelectric barrier polarisation direction produces a sizable change in resistance of the junction—a phenomenon known as the tunnelling electroresistance effect. From a fundamental perspective, ferroelectric tunnel junctions and their version with ferromagnetic electrodes, i.e., multiferroic tunnel junctions, are testbeds for studying the underlying mechanisms of tunnelling electroresistance as well as the interplay between electric and magnetic degrees of freedom and their effect on transport. From a practical perspective, ferroelectric tunnel junctions hold promise for disruptive device applications. In a very short time, they have traversed the path from basic model predictions to prototypes for novel non-volatile ferroelectric random access memories with non-destructive readout. This remarkable progress is to a large extent driven by a productive cycle of predictive modelling and innovative experimental effort. In this review article, we outline the development of the ferroelectric tunnel junction concept and the role of theoretical modelling in guiding experimental work. We discuss a wide range of physical phenomena that control the functional properties of ferroelectric tunnel junctions and summarise the state-of-the-art achievements in the field.

  13. Transport processes and reduction of IcRn product in YBaCuO/PrBaCuO/YBaCuO ramp-type Josephson junctions

    NARCIS (Netherlands)

    Boguslavskij, Y.M.; Gao, J.; Rijnders, A.J.H.M.; Terpstra, D.; Gerritsma, G.J.; Rogalla, H.

    1993-01-01

    The mechanisms of current passage and the causes of IcRn (critical-current normal-resistance) product reduction of YBCO/PBCO/YBCO ramp-type junctions are analyzed. At PBCO (PrBa2Cu3Ox ) barrier thicknesses L=8-20 nm the junction characteristics are determined by the thickness of the PBCO barrier and

  14. Experimental investigation of the influence of junctions on concrete gas permeability; Etude experimentale de l'influence des jonctions sur la permeabilite au gaz des betons

    Energy Technology Data Exchange (ETDEWEB)

    Poyet, St. [CEA Saclay, Dept. de Physico-Chimie (DEN/DANS/DPC/SCCME/LECBA), 91 - Gif sur Yvette (France); Pineau, F. [Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay-Malabry (France)

    2007-07-01

    Permeability is a key parameter in the case of nuclear waste disposal containers (evacuation of hydrogen generated by radiolysis and long-term containment of radionuclides) and nuclear power plants (confinement of radioactive gas in accidental conditions). The presence of construction junctions (formed between previously laid concrete and fresh concrete) might cause an increase of the permeability and question the durability of such concrete structures. In order to quantify the influence of the junctions on the permeability, specimens including a vertical junction were cast. Two different methods for the junction preparation were used: abrasion and chemical deactivation. The permeability was characterized for each specimen using nitrogen. The results show that the permeability to gas of the specimens increases depending on the type of preparation of the junction. The permeability of the junction zone is estimated using elementary homogenization. (authors)

  15. Highly sensitive photodetection using a microwave-coupled BaPb0.7Bi0.3O3 Josephson junction array

    Science.gov (United States)

    Ito, Minoru; Enomoto, Youichi; Murakami, Toshiaki

    1983-08-01

    The BaPb0.7Bi0.3O3 sputtered film possesses tunnel Josephson junctions at boundary layers [boundary Josephson junction (BJJ)] normal to the film plane in a homogeneous junction array. The film has high efficiency for optical irradiation of the junctions because of the high optical transparency. The letter presents the optical effect on the current-voltage characteristics for this Josephson junction array locked to a microwave field. The microwave-induced hysteresis loop caused by voltage locking among junctions in a microwave field is highly sensitive to optical illumination with as low an incident power as a few nanowatts. This probably can be exploited in a future, highly sensitive photodetector.

  16. Macrophages and dendritic cells express tight junction proteins and exchange particles in an in vitro model of the human airway wall.

    Science.gov (United States)

    Blank, Fabian; Wehrli, Marc; Lehmann, Andrea; Baum, Oliver; Gehr, Peter; von Garnier, Christophe; Rothen-Rutishauser, Barbara M

    2011-01-01

    The human airway epithelium serves as structural and functional barrier against inhaled particulate antigen. Previously, we demonstrated in an in vitro epithelial barrier model that monocyte derived dendritic cells (MDDC) and monocyte derived macrophages (MDM) take up particulate antigen by building a trans-epithelial interacting network. Although the epithelial tight junction (TJ) belt was penetrated by processes of MDDC and MDM, the integrity of the epithelium was not affected. These results brought up two main questions: (1) Do MDM and MDDC exchange particles? (2) Are those cells expressing TJ proteins, which are believed to interact with the TJ belt of the epithelium to preserve the epithelial integrity? The expression of TJ and adherens junction (AJ) mRNA and proteins in MDM and MDDC monocultures was determined by RT-PCR, and immunofluorescence, respectively. Particle uptake and exchange was quantified by flow cytometry and laser scanning microscopy in co-cultures of MDM and MDDC exposed to polystyrene particles (1 μm in diameter). MDM and MDDC constantly expressed TJ and AJ mRNA and proteins. Flow cytometry analysis of MDM and MDDC co-cultures showed increased particle uptake in MDDC while MDM lost particles over time. Quantitative analysis revealed significantly higher particle uptake by MDDC in co-cultures of epithelial cells with MDM and MDDC present, compared to co-cultures containing only epithelial cells and MDDC. We conclude from these findings that MDM and MDDC express TJ and AJ proteins which could help to preserve the epithelial integrity during particle uptake and exchange across the lung epithelium.

  17. Charge transport in nanoscale junctions.

    Science.gov (United States)

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-03

    many particle excitations, new surface states in semiconductor electrodes, various mechanisms for single molecule rectification of the current, inelastic electron spectra and SERS spectroscopy. Three terminal architectures allowing (electrochemical) gating and transistor effects. Electrochemical nanojunctions and gating: intermolecular electron transfer in multi-redox metalloproteins, contact force modulation, characteristic current-noise patterns due to conformational fluctuations, resonance effects and electrocatalysis. Novel architectures: linear coupled quantum-dot-bridged junctions, electrochemical redox mediated transfer in two center systems leading to double maxima current-voltage plots and negative differential resistance, molecular-nanoparticle hybrid junctions and unexpected mesoscopic effects in polymeric wires. Device integration: techniques for creating stable metal/molecule/metal junctions using 'nano-alligator clips' and integration with 'traditional' silicon-based technology. The Guest Editors would like to thank all of the authors and referees of this special issue for their meticulous work in making each paper a valuable contribution to this research area, the early-bird authors for their patience, and Journal of Physics: Condensed Matter editorial staff in Bristol for their continuous support.

  18. Josephson tunnel junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M.P.

    2006-07-01

    Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al{sub 2}O{sub 3} tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or {pi} coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, {pi}) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-{pi} Josephson junction. At a certain temperature this 0-{pi} junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum {phi}{sub 0}. Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T {yields} 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

  19. Model Building to Facilitate Understanding of Holliday Junction and Heteroduplex Formation, and Holliday Junction Resolution

    Science.gov (United States)

    Selvarajah, Geeta; Selvarajah, Susila

    2016-01-01

    Students frequently expressed difficulty in understanding the molecular mechanisms involved in chromosomal recombination. Therefore, we explored alternative methods for presenting the two concepts of the double-strand break model: Holliday junction and heteroduplex formation, and Holliday junction resolution. In addition to a lecture and…

  20. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions

    DEFF Research Database (Denmark)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin;

    2007-01-01

    . In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing......Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes...... the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs...

  1. Dislocation Multi-junctions and Strain Hardening

    Energy Technology Data Exchange (ETDEWEB)

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T

    2006-06-20

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  2. Mefloquine gap junction blockade and risk of pregnancy loss.

    Science.gov (United States)

    Nevin, Remington Lee

    2012-09-01

    Obstetric use of the antimalarial drug mefloquine has historically been discouraged during the first trimester and immediately before conception owing to concerns of potential fetal harm. With the rise of resistance to the antimalarial drug sulfadoxine-pyrimethamine (SP), mefloquine is now being considered as a replacement for SP for universal antenatal administration to women from malaria-endemic regions. Recent recommendations have also suggested that mefloquine may be used cautiously among pregnant travelers who cannot otherwise avoid visiting these areas. Mefloquine has been demonstrated to cause blockade of gap junction protein alpha 1 (GJA1) gap junction intercellular communication (GJIC), and recent evidence suggests that GJA1 GJIC is critical to successful embryonic implantation and early placental development. During routine use, mefloquine accumulates in organ and peripheral tissue, crosses the blood-placental barrier, and may plausibly accumulate in developing decidua and trophoblast at concentrations sufficient to interfere with GJA1 GJIC and, thus, cause deleterious effects on fetal outcomes. This conclusion is supported by epidemiological evidence that demonstrates use of the drug during early development is associated with an increased risk of miscarriage and stillbirth. Confirmatory studies are pending, but the available experimental and epidemiological evidence support renewed adherence, where feasible, to existing mefloquine package insert guidance that women avoid the drug during the periconceptional period.

  3. Scattering of MCF7 cells by heregulin ß-1 depends on the MEK and p38 MAP kinase pathway.

    Directory of Open Access Journals (Sweden)

    Rintaro Okoshi

    Full Text Available Heregulin (HRG β1 signaling promotes scattering of MCF7 cells by inducing breakdown of adherens and tight junctions. Here, we show that stimulation with HRG-β1 causes the F-actin backbone of junctions to destabilize prior to the loss of adherent proteins and scattering of the cells. The adherent proteins dissociate and translocate from cell-cell junctions to the cytosol. Moreover, using inhibitors we show that the MEK1 pathway is required for the disappearance of F-actin from junctions and p38 MAP kinase activity is essential for scattering of the cells. Upon treatment with a p38 MAP kinase inhibitor, adherens junction complexes immediately reassemble, most likely in the cytoplasm, and move to the plasma membrane in cells dissociated by HRG-β1 stimulation. Subsequently, tight junction complexes form, most likely in the cytoplasm, and move to the plasma membrane. Thus, the p38 MAP kinase inhibitor causes a re-aggregation of scattered cells, even in the presence of HRG-β1. These results suggest that p38 MAP kinase signaling to adherens junction proteins regulates cell aggregation, providing a novel understanding of the regulation of cell-cell adhesion.

  4. Bias dependence of synergistic radiation effects induced by electrons and protons on silicon bipolar junction transistors

    Science.gov (United States)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Ma, Guoliang; Xiao, Liyi

    2015-06-01

    Bias dependence on synergistic radiation effects caused by 110 keV electrons and 170 keV protons on the current gain of 3DG130 NPN bipolar junction transistors (BJTs) is studied in this paper. Experimental results indicate that the influence induced by 170 keV protons is always enhancement effect during the sequential irradiation. However, the influence induced by 110 keV electrons on the BJT under various bias cases is different during the sequential irradiation. The transition fluence of 110 keV electrons is dependent on the bias case on the emitter-base junction of BJT.

  5. Testing of junctional tourniquets by military medics to control simulated groin hemorrhage.

    Science.gov (United States)

    Kragh, John F; Parsons, Donald L; Kotwal, Russ S; Kheirabadi, Bijan S; Aden, James K; Gerhardt, Robert T; Baer, David G; Dubick, Michael A

    2014-01-01

    Junctional hemorrhage is a common cause of death on the battlefield, but there is no documented direct comparison for the use of junctional tourniquet models by US medics. The purpose of this testing is to assess military medic experience with the use of junctional tourniquets in simulated out-of-hospital trauma care. Nine medics (seven men and two women) used four different junctional tourniquets: Combat Ready Clamp™ (CRoC™; http://www.combatmedicalsystems .com), Abdominal Aortic and Junctional Tourniquet™ (AAJT™; http://www.compressionworks.net), Junctional Emergency Treatment Tool (JETT™; http://www.narescue .com), and SAM Junctional Tourniquet® (SJT®; http://www.sammedical.com/products). These medics also acted as simulated casualties. Effectiveness percentages, as measured by stopped distal pulse by Doppler auscultation, and time to effectiveness were recorded in two tests per tourniquet (72 total tests). Tourniquet users ranked their preference of model by answering the question: "If you had to go to war today and you could only choose one, which tourniquet would you choose to bring?" All tourniquets used were safe under the conditions of this study. Both the SJT and the CRoC had high effectiveness percentages; their rate difference was not statistically significant. The SJT and the CRoC had fast times to effectiveness; their time difference was not statistically significant. Users preferred the SJT and the CRoC; their ranked difference was not statistically significant. The SJT and the CRoC were equally effective and fast and were preferred by the participants. 2014.

  6. Improved electrical properties of n-n and p-n Si/SiC junctions with thermal annealing treatment

    Science.gov (United States)

    Liang, J.; Nishida, S.; Arai, M.; Shigekawa, N.

    2016-07-01

    The effects of annealing process on the electrical properties of n+-Si/n-SiC and p+-Si/n-SiC junctions fabricated by using surface-activated bonding are investigated. It is found by measuring the current-voltage (I-V) characteristics of n+-Si/n-SiC junctions that the reverse-bias current and the ideality factor decreased to 2.0 × 10-5 mA/cm2 and 1.10, respectively, after the junctions annealing at 700 °C. The flat band voltages of n+-Si/n-SiC and p+-Si/n-SiC junctions obtained from capacitance-voltage (C-V) measurements decreased with increasing annealing temperature. Furthermore, their flat band voltages are very close to each other irrespective of the annealing temperature change, which suggests that the Fermi level is still pinned at the bonding interface even for the junctions annealing at high temperature and the interface state density causing Fermi level pinning varies with the junctions annealing. The reverse characteristics of n+-Si/n-SiC junctions are in good agreement with the calculations based on thermionic field emission. In addition, the calculated donor concentration of 4H-SiC epi-layers and flat band voltage is consistent with the values obtained from C-V measurements.

  7. Role of gap junction channel in the development of beat-to-beat action potential repolarization variability and arrhythmias.

    Science.gov (United States)

    Magyar, Janos; Banyasz, Tamas; Szentandrassy, Norbert; Kistamas, Kornel; Nanasi, Peter P; Satin, Jonathan

    2015-01-01

    The short-term beat-to-beat variability of cardiac action potential duration (SBVR) occurs as a random alteration of the ventricular repolarization duration. SBVR has been suggested to be more predictive of the development of lethal arrhythmias than the action potential prolongation or QT prolongation of ECG alone. The mechanism underlying SBVR is not completely understood but it is known that SBVR depends on stochastic ion channel gating, intracellular calcium handling and intercellular coupling. Coupling of single cardiomyocytes significantly decreases the beat-to-beat changes in action potential duration (APD) due to the electrotonic current flow between neighboring cells. The magnitude of this electrotonic current depends on the intercellular gap junction resistance. Reduced gap junction resistance causes greater electrotonic current flow between cells, and reduces SBVR. Myocardial ischaemia (MI) is known to affect gap junction channel protein expression and function. MI increases gap junction resistance that leads to slow conduction, APD and refractory period dispersion, and an increase in SBVR. Ultimately, development of reentry arrhythmias and fibrillation are associated post-MI. Antiarrhythmic drugs have proarrhythmic side effects requiring alternative approaches. A novel idea is to target gap junction channels. Specifically, the use of gap junction channel enhancers and inhibitors may help to reveal the precise role of gap junctions in the development of arrhythmias. Since cell-to-cell coupling is represented in SBVR, this parameter can be used to monitor the degree of coupling of myocardium.

  8. Created-by-current states in long Josephson junctions

    Science.gov (United States)

    Boyadjiev, T. L.; Andreeva, O. Yu.; Semerdjieva, E. G.; Shukrinov, Yu. M.

    2008-08-01

    Critical curves "critical current-external magnetic field" of long Josephson junctions with inhomogeneity and variable width are studied. We demonstrate the existence of regions of magnetic field where some fluxon states are stable only if the external current through the junction is different from zero. Position and size of such regions depend on the length of the junction, its geometry, parameters of inhomogeneity and form of the junction. The noncentral (left and right) pure fluxon states appear in the inhomogeneous Josephson junction with the increase in the junction length. We demonstrate new bifurcation points with change in width of the inhomogeneity and amplitude of the Josephson current through the inhomogeneity.

  9. Thermionic refrigeration at CNT-CNT junctions

    Science.gov (United States)

    Li, C.; Pipe, K. P.

    2016-10-01

    Monte Carlo (MC) simulation is used to study carrier energy relaxation following thermionic emission at the junction of two van der Waals bonded single-walled carbon nanotubes (SWCNTs). An energy-dependent transmission probability gives rise to energy filtering at the junction, which is predicted to increase the average electron transport energy by as much as 0.115 eV, leading to an effective Seebeck coefficient of 386 μV/K. MC results predict a long energy relaxation length (˜8 μm) for hot electrons crossing the junction into the barrier SWCNT. For SWCNTs of optimal length, an analytical transport model is used to show that thermionic cooling can outweigh parasitic heat conduction due to high SWCNT thermal conductivity, leading to a significant cooling capacity (2.4 × 106 W/cm2).

  10. Silicon fiber with p-n junction

    Energy Technology Data Exchange (ETDEWEB)

    Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, 312 Holden Hall, Blacksburg, Virginia 24060 (United States)

    2014-09-22

    In this study, we fabricated a p-n junction in a fiber with a phosphorous doped silicon core and fused silica cladding. The fibers were fabricated via a hybrid process of the core-suction and melt-draw techniques and maintained overall diameters ranging from 200 to 900 μm and core diameters of 20–800 μm. The p-n junction was formed by doping the fiber with boron and confirmed via the current-voltage characteristic. The demonstration of a p-n junction in a melt-drawn silicon core fiber paves the way for the seamless integration of optical and electronic devices in fibers.

  11. Vortex structures in exponentially shaped Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Semerdjieva, E. G.; Boyadjiev, T. L.

    2005-04-01

    We report the numerical calculations of the static vortex structure and critical curves in exponentially shaped long Josephson junctions for in-line and overlap geometries. Stability of the static solutions is investigated by checking the sign of the smallest eigenvalue of the associated Sturm-Liouville problem. The change in the junction width leads to the renormalization of the magnetic flux in comparison with the case of a linear one-dimensional model. We study the influence of the model's parameters, and particularly, the shape parameter on the stability of the states of the magnetic flux. We compare the vortex structure and critical curves for the in-line and overlap geometries. Our numerically constructed critical curve of the Josephson junction matches well with the experimental one.

  12. Holographic Josephson Junction from Massive Gravity

    CERN Document Server

    Hu, Ya-Peng; Zeng, Hua-Bi; Zhang, Hai-Qing

    2015-01-01

    We study the holographic superconductor-normal metal-superconductor (SNS) Josephon junction in the massive gravity. In the homogeneous case of the chemical potential, we find that the graviton mass will make the normal metal-superconductor phase transition harder to take place. In the holographic model of Josephson junction, it is found that the maximal tunneling current will decrease according to the graviton mass. Besides, the coherence length of the junction decreases as well with respect to the graviton mass. If one interprets the graviton mass as the effect of momentum dissipation in the boundary field theory, it indicates that the stronger the momentum dissipation is, the smaller the coherence length is.

  13. Characterization of magnetic tunnel junction test pads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Kjær, Daniel; Nielsen, Peter Folmer

    2015-01-01

    We show experimentally as well as theoretically that patterned magnetic tunnel junctions can be characterized using the current-in-plane tunneling (CIPT) method, and the key parameters, the resistance-area product (RA) and the tunnel magnetoresistance (TMR), can be determined. The CIPT method...... on square tunnel junction pads with varying sizes and analyze the measured data using both the original and the modified CIPT model. Thus, we determine in which sample size range the modified CIPT model is needed to ensure validity of the extracted sample parameters, RA and TMR. In addition, measurements...... as a function of position on a square tunnel junction pad are used to investigate the sensitivity of the measurement results to probe misalignment....

  14. Overdamped Josephson junctions for digital applications

    Energy Technology Data Exchange (ETDEWEB)

    Febvre, P., E-mail: Pascal.Febvre@univ-savoie.fr [University of Savoie, IMEP-LAHC – CNRS UMR5130, 73376 Le Bourget du Lac (France); De Leo, N.; Fretto, M.; Sosso, A. [I.N.Ri.M., Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino (Italy); Belogolovskii, M. [Donetsk Institute for Physics and Engineering, 72 R. Luxemburg str., 83114 Donetsk (Ukraine); Collot, R. [University of Savoie, IMEP-LAHC – CNRS UMR5130, 73376 Le Bourget du Lac (France); Lacquaniti, V. [I.N.Ri.M., Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino (Italy)

    2013-01-15

    Highlights: ► Properties of self-shunted sub-micron Nb/Al–AlO{sub x}/Nb SNIS junctions are studied. ► 1–100 kA/cm{sup 2} current densities and 0.1–0.7 mV critical voltages are obtained. ► The critical voltage-vs-temperature behavior of SNIS junctions is discussed. ► Numerical results showing an effect of the aluminum film thickness are presented. ► A Josephson balanced comparator is studied for different temperatures of operation. -- Abstract: An interesting feature of Superconductor–Normal metal–Superconductor Josephson junctions for digital applications is due to their non-hysteretic current–voltage characteristics in a broad temperature range below T{sub c}. This allows to design Single-Flux-Quantum (SFQ) cells without the need of external shunts. Two advantages can be drawn from this property: first the SFQ cells can be more compact which leads to a more integrated solution towards nano-devices and more complex circuits; second the absence of electrical parasitic elements associated with the wiring of resistors external to the Josephson junctions increases the performance of SFQ circuits, in particular regarding the ultimate speed of operation. For this purpose Superconductor–Normal metal–Insulator–Superconductor Nb/Al–AlO{sub x}/Nb Josephson junctions have been recently developed at INRiM with aluminum layer thicknesses between 30 and 100 nm. They exhibit non-hysteretic current–voltage characteristics with I{sub c}R{sub n} values higher than 0.5 mV in a broad temperature range and optimal Stewart McCumber parameters at 4.2 K for RSFQ applications. The main features of obtained SNIS junctions regarding digital applications are presented.

  15. Forward voltage short-pulse technique for measuring high power laser array junction temperature

    Science.gov (United States)

    Meadows, Byron L. (Inventor); Amzajerdian, Frazin (Inventor); Barnes, Bruce W. (Inventor); Baker, Nathaniel R. (Inventor)

    2012-01-01

    The present invention relates to a method of measuring the temperature of the P-N junction within the light-emitting region of a quasi-continuous-wave or pulsed semiconductor laser diode device. A series of relatively short and low current monitor pulses are applied to the laser diode in the period between the main drive current pulses necessary to cause the semiconductor to lase. At the sufficiently low current level of the monitor pulses, the laser diode device does not lase and behaves similar to an electronic diode. The voltage across the laser diode resulting from each of these low current monitor pulses is measured with a high degree of precision. The junction temperature is then determined from the measured junction voltage using their known linear relationship.

  16. Vibrationally dependent electron-electron interactions in resonant electron transport through single-molecule junctions

    Science.gov (United States)

    Erpenbeck, A.; Härtle, R.; Bockstedte, M.; Thoss, M.

    2016-03-01

    We investigate the role of electronic-vibrational coupling in resonant electron transport through single-molecule junctions, taking into account that the corresponding coupling strengths may depend on the charge and excitation state of the molecular bridge. Within an effective-model Hamiltonian approach for a molecule with multiple electronic states, this requires to extend the commonly used model and include vibrationally dependent electron-electron interaction. We use Born-Markov master equation methods and consider selected models to exemplify the effect of the additional interaction on the transport characteristics of a single-molecule junction. In particular, we show that it has a significant influence on local cooling and heating mechanisms, it may result in negative differential resistance, and it may cause pronounced asymmetries in the conductance map of a single-molecule junction.

  17. Pathogenic role of glomerulo-tubular junction stenosis in glomerulocystic disease.

    Science.gov (United States)

    Hotta, O; Sato, M; Furuta, T; Taguma, Y

    1999-03-01

    Glomerulocystic disease is an uncommon cystic renal condition characterized by cystic dilatation forming a glomerular cyst. The pathogenesis of this familial disease is unknown. We performed a serial section study using a biopsy specimen of a 16-year old female patient with glomerular cystic disease who had a family history of end stage renal failure. A total of 14 different glomeruli were analyzed, four of which exhibited a cystic appearance. Five glomerulotubular junctions were observed by serial sections, two of which had a stenotic appearance where glomerular cystic changes and periglomerular fibrosis were observed concomitantly. There were no such cystic glomerular changes in the other three glomeruli with non-stenotic glomerulo-tubular junctions. These findings suggest that the glomerular cystic lesion develops as a consequence of glomerulo-tubular junctional stenosis probably caused by periglomerular fibrosis.

  18. Tunnel anisotropic magnetoresistance in CoFeB|MgO|Ta junctions

    Energy Technology Data Exchange (ETDEWEB)

    Hatanaka, S.; Miwa, S., E-mail: miwa@mp.es.osaka-u.ac.jp; Matsuda, K.; Nawaoka, K.; Tanaka, K.; Morishita, H.; Goto, M.; Mizuochi, N.; Shinjo, T.; Suzuki, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2015-08-24

    We found that CoFeB|MgO|Ta tunnel junctions exhibit tunnel anisotropic magnetoresistance (TAMR) at room temperature. The tunnel junctions exhibit positive magnetoresistance with the application of a magnetic field normal to the film plane. The dependencies on the applied magnetic field angle and MgO thickness reveal that the magnetoresistance originates from the TAMR, caused by the spin polarization and the spin-orbit interaction at the CoFeB|MgO interface. We also found that the TAMR can be used to detect ferromagnetic resonance in the CoFeB. This detection method could be useful for the characterization of nanomagnets that are free from the spin-transfer effect and the stray field of a reference layer, unlike conventional magnetic tunnel junctions.

  19. Gap junctions enhancer combined with Vaughan Williams class III antiarrhythmic drugs, a promising antiarrhythmic method?

    Science.gov (United States)

    Li, Lian-dong; Zhang, Cun-tai; Ruan, Lei; Ni, Ming-ke; Quan, Xiao-qing

    2011-01-01

    Arrhythmias is one of the leading causes of death in the world. Current antiarrhythmic drugs are limited by unsatisfactory efficacy and adverse effects such as proarrhythmias. Reentry mechanism plays an important role in persistence of arrhythmias. Reentry can only continue when reentry path-length is longer than cardiac wavelength which is equal to the product of conduction velocity (CV) and effective refractory period (ERP). Gap junctions uncoupling is associated with proarrhythmic CV slowing and transmural dispersion of repolarization (TDR) increasing in many cardiac diseases. Vaughan Williams class III antiarrhythmic drugs prolong ERP with an augmented TDR which is the main mechanism of the proarrhythmic effects. Gap junctions enhancer can augment CV and diminish TDR. As a result, gap junctions enhancer combined with class III drugs may be a promising antiarrhythmic method.

  20. Direct observation of large quantum interference effect in anthraquinone solid-state junctions.

    Science.gov (United States)

    Rabache, Vincent; Chaste, Julien; Petit, Philippe; Della Rocca, Maria Luisa; Martin, Pascal; Lacroix, Jean-Christophe; McCreery, Richard L; Lafarge, Philippe

    2013-07-17

    Quantum interference in cross-conjugated molecules embedded in solid-state devices was investigated by direct current-voltage and differential conductance transport measurements of anthraquinone (AQ)-based large area planar junctions. A thin film of AQ was grafted covalently on the junction base electrode by diazonium electroreduction, while the counter electrode was directly evaporated on top of the molecular layer. Our technique provides direct evidence of a large quantum interference effect in multiple CMOS compatible planar junctions. The quantum interference is manifested by a pronounced dip in the differential conductance close to zero voltage bias. The experimental signature is well developed at low temperature (4 K), showing a large amplitude dip with a minimum >2 orders of magnitude lower than the conductance at higher bias and is still clearly evident at room temperature. A temperature analysis of the conductance curves revealed that electron-phonon coupling is the principal decoherence mechanism causing large conductance oscillations at low temperature.

  1. Multiplication in Silicon p-n Junctions

    DEFF Research Database (Denmark)

    Moll, John L.

    1965-01-01

    Multiplication values were measured in the collector junctions of silicon p-n-p and n-p-n transistors before and after bombardment by 1016 neutrons/cm2. Within experimental error there was no change either in junction fields, as deduced from capacitance measurements, or in multiplication values...... in any of the transistors. The implication is that the electron and hole ionization rates did not change as a result of the addition of extra scattering centers. This result is in direct contradiction to observations of Lee et al. The most likely explanation for the discrepancy is erroneous determination...

  2. Fast transient response of novel Peltier junctions

    Energy Technology Data Exchange (ETDEWEB)

    Hoyos, G.E.; Rao, K.R.; Jerger, D.

    1977-01-01

    The fast transient response of a thermoelectric (TE) cooler with novel geometry is discussed. This geometry involves conical semiconductor legs whose hot to cold junction cross-sectional area ratios can be varied. The novel TE junctions are fabricated such that the thermal capacitance and electrical conductance are decreased while simultaneously increasing the thermal resistance. The experimental apparatus which includes the vacuum system, power supplies, pulse and control circuitry, sensing and measuring instrumentation etc. is described. With narrow pulse width and large amplitudes, additional cooling of the order of 45/sup 0/C below the steady-state maximum with recovery times in the range of 1 to 3 sec is obtained.

  3. The Geometric Field at a Josephson Junction

    CERN Document Server

    Atanasov, Victor

    2016-01-01

    A geometric potential from the kinetic term of a constrained to a curved hyper-plane of space-time quantum superconducting condensate is derived. An energy conservation relation involving the geometric field at every material point in the superconductor is demonstrated. At a Josephson junction the energy conservation relation implies the possibility to transform electric energy into geometric field energy, that is curvature of space-time. Experimental procedures to verify that the Josephson junction can act as a voltage-to-curvature converter are discussed.

  4. Microscopic tunneling theory of long Josephson junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Hattel, Søren A.; Samuelsen, Mogens Rugholm

    1992-01-01

    We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detai......We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate...

  5. Rectangular-to-circular groove waveguide junction

    Institute of Scientific and Technical Information of China (English)

    CUI; Licheng; (崔立成); YANG; Hongsheng; (杨鸿生)

    2003-01-01

    Mode matching method is used to analyze the scattering characteristics of the rectangular-to-circular groove waveguide junction. Firstly, the scattering matrix equation is obtained by matching the electromagnetic fields at the boundary of the junction. The scattering coefficients can be obtained from the equation. Secondly the scattering characteristics of the iris with rectangular window positioned in circular groove waveguide are briefly analyzed. Thirdly, the convergent problem is discussed and the numerical results are given. At last experiment is made and good agreement is found between the calculated results and the measured results.

  6. Electroplated Ni on the PN Junction Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm{sup 2}. The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased.

  7. Morphological adaptation and protein modulation of myotendinous junction following moderate aerobic training.

    Science.gov (United States)

    Curzi, Davide; Baldassarri, Valentina; De Matteis, Rita; Salamanna, Francesca; Bolotta, Alessandra; Frizziero, Antonio; Fini, Milena; Marini, Marina; Falcieri, Elisabetta

    2015-04-01

    Myotendinous junction is the muscle-tendon interface through which the contractile force can be transferred from myofibrils to the tendon extracellular matrix. At the ultrastructural level, aerobic training can modify the distal myotendinous junction of rat gastrocnemius, increasing the contact area between tissues. The aim of this work is to investigate the correlation between morphological changes and protein modulation of the myotendinous junction following moderate training. For this reason, talin, vinculin and type IV collagen amount and spatial distribution were investigated by immunohistochemistry and confocal microscopy. The images were then digitally analyzed by evaluating fluorescence intensity. Morphometric analysis revealed a significant increased thickening of muscle basal lamina in the trained group (53.1 ± 0.4 nm) with respect to the control group (43.9 ± 0.3 nm), and morphological observation showed the presence of an electron-dense area in the exercised muscles, close to the myotendinous junction. Protein concentrations appeared significantly increased in the trained group (talin +22.2%; vinculin +22.8% and type IV collagen +11.8%) with respect to the control group. Therefore, our findings suggest that moderate aerobic training induces/causes morphological changes at the myotendinous junction, correlated to the synthesis of structural proteins of the muscular basal lamina and of the cytoskeleton.

  8. pn-Junction Delineation in Si Devices Using Scanning Capacitance Spectroscopy

    Science.gov (United States)

    Edwards, Hal

    2000-03-01

    The scanning capacitance microscope (SCM) is a carrier-sensitive imaging tool based upon the well-known scanning-probe microscope (SPM). Scanning capacitance spectroscopy (SCS) is a new way to utilize an SCM to delineate pn junctions in Si devices. SCS produces two-dimensional pn-junction maps that show features as small as 10 nm. SCS also provides an estimate of the pn-junction depletion width and hence the doping level near the pn junction. We report SCS measurements of deep-submicron field-effect transistors, showing the source-drain extender profile. We show SCM and SCS data in a failure-analysis application, in which we determined the cause of a leaky field-effect transistor. SCM and SCS are powerful tools for Si bipolar transistors, in which the doping-related structures are quite complex. We show microscopic evidence of the narrow-emitter effect, and image the width of the pn junction to explain an electric field-induced hot-carrier reliability issue. We show a comparison of top-view and cross-sectional SCS measurements of nwell-nwell shallow-trench isolation structures, to reveal the effects of photoresist scumming in sub-design-rule isolation widths. We show initial results on a method to delineate constant-potential contours within the depletion region. We discuss the limits to our present understanding of SCM and SCS and some potential sources of error.

  9. Photocurrent generation in lateral graphene p-n junction created by electron-beam irradiation

    KAUST Repository

    Yu, Xuechao

    2015-07-08

    Graphene has been considered as an attractive material for optoelectronic applications such as photodetectors owing to its extraordinary properties, e.g. broadband absorption and ultrahigh mobility. However, challenges still remain in fundamental and practical aspects of the conventional graphene photodetectors which normally rely on the photoconductive mode of operation which has the drawback of e.g. high dark current. Here, we demonstrated the photovoltaic mode operation in graphene p-n junctions fabricated by a simple but effective electron irradiation method that induces n-type doping in intrinsic p-type graphene. The physical mechanism of the junction formation is owing to the substrate gating effect caused by electron irradiation. Photoresponse was obtained for this type of photodetector because the photoexcited electron-hole pairs can be separated in the graphene p-n junction by the built-in potential. The fabricated graphene p-n junction photodetectors exhibit a high detectivity up to ~3 × 1010 Jones (cm Hz1/2 W−1) at room temperature, which is on a par with that of the traditional III–V photodetectors. The demonstrated novel and simple scheme for obtaining graphene p-n junctions can be used for other optoelectronic devices such as solar cells and be applied to other two dimensional materials based devices.

  10. Common features of a vortex structure in long exponentially shaped Josephson junctions and Josephson junctions with inhomogeneities

    Science.gov (United States)

    Boyadjiev, T. L.; Semerdjieva, E. G.; Shukrinov, Yu. M.

    2007-09-01

    We study the vortex structure in three different models of the long Josephson junction: the exponentially shaped Josephson junction and the Josephson junctions with the resistor and the shunt inhomogeneities in the barrier layer. For these three models the critical curves “critical current-magnetic field” are numerically constructed. We develop the idea of the equivalence of the exponentially shaped Josephson junction and the rectangular junction with the distributed inhomogeneity and demonstrate that at some parameters of the shunt and the resistor inhomogeneities in the ends of the junction the corresponding critical curves are very close to the exponentially shaped one.

  11. Common features of a vortex structure in long exponentially shaped Josephson junctions and Josephson junctions with inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Boyadjiev, T.L. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Semerdjieva, E.G. [Plovdiv University, 24 Tzar Asen Str., Plovdiv 4000 (Bulgaria); Shukrinov, Yu.M. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)], E-mail: shukrinv@theor.jinr.ru

    2007-09-01

    We study the vortex structure in three different models of the long Josephson junction: the exponentially shaped Josephson junction and the Josephson junctions with the resistor and the shunt inhomogeneities in the barrier layer. For these three models the critical curves 'critical current-magnetic field' are numerically constructed. We develop the idea of the equivalence of the exponentially shaped Josephson junction and the rectangular junction with the distributed inhomogeneity and demonstrate that at some parameters of the shunt and the resistor inhomogeneities in the ends of the junction the corresponding critical curves are very close to the exponentially shaped one.

  12. Pancreaticobiliary reflux in patients with a normal pancreaticobiliary junction:Pathologic implications

    Institute of Scientific and Technical Information of China (English)

    Marcelo A Beltrán

    2011-01-01

    Knowledge on pancreaticobiliary reflux in normal pancreaticobiliary junction and its pathologic implications has experienced tremendous progress during the last few years.This editorial reviews the current knowledge on this condition and its pathological implications on gallbladder diseases.The following aspects were defined appropriate for discussion:(1) Evidence of carcinogenesis associated with pancreaticobiliary reflux; (2) Evidence of pancreaticobiliary reflux in normal pancreaticobiliary junction; and (3) Evidence of sphincter of Oddi (SO) dysfunction as a cause of pancreaticobiliary reflux in normal pancreaticobiliary junction.The articles reviewed were selected and classified according to five levels of evidence:LevelⅠ,meta-analysis double-blind randomized clinical trials,Level Ⅱ,cohort non-blinded studies and non-randomized clinical trials,Level Ⅲ, good quality case-control studies and non-randomized cohort studies,Level Ⅳ,case series and poor quality case-control studies,and Level Ⅴ,case report articles and experts' opinion.Evidence levels Ⅱ,Ⅲ,Ⅳ and Ⅴ were found to support biliary carcinogenesis associated with pancreaticobiliary reflux in normal and abnormal pancreaticobiliary junction.The same levels of evidence were found to support the common occurrence of pancreaticobiliary reflux in normal pancreaticobiliary junction, and SO dysfunction as the most plausible cause of this condition.Although an important body of research has been published regarding pancreaticobiliary reflux in normal pancreaticobiliary junction and its clinical significance, the current evidence does not fully support what has been suggested.Studies with evidence level I have not been undertaken.This is a fascinating subject of study,and if finally supported by evidence level I, the importance of this condition will constitute a major breakthrough in biliary pathology.

  13. A study on electrical contact at the PEDOT:PSS electrode/molecule interface in large-area molecular junctions

    Science.gov (United States)

    Jeong, Inho; Song, Hyunwook

    2017-08-01

    We have investigated the effect of the PEDOT:PSS electrode/molecule contact on the charge transport characteristics of large-area molecular junctions. We incorporated two different benzenethiolate molecules into the molecular junctions: 4-methylbenzenethiol (MBT) and benzene- 1,4-dithiol (BDT). They have an identical backbone structure but different top end-groups. From statistical analysis, we found that the tunneling transport behavior showed a significant difference between the two prototype conjugated molecules, which was attributed to their distinct electrical contacts at the PEDOT:PSS electrode/molecule interface. We also observed an enhancement of the junction conductance at elevated temperatures, which would be caused by the increased grain size of the conducting PEDOT-rich cores and the removal of residual solvents or water in the junctions.

  14. Gap junctional regulation of pressure, fluid force, and electrical fields in the epigenetics of cardiac morphogenesis and remodeling.

    Science.gov (United States)

    Seki, Akiko; Nishii, Kiyomasa; Hagiwara, Nobuhisa

    2015-05-15

    Epigenetic factors of pressure load, fluid force, and electrical fields that occur during cardiac contraction affect cardiac development, morphology, function, and pathogenesis. These factors are orchestrated by intercellular communication mediated by gap junctions, which synchronize action potentials and second messengers. Misregulation of the gap junction protein connexin (Cx) alters cardiogenesis, and can be a pathogenic factor causing cardiac conduction disturbance, fatal arrhythmia, and cardiac remodeling in disease states such as hypertension and ischemia. Changes in Cx expression can occur even when the DNA sequence of the Cx gene itself is unaltered. Posttranslational modifications might reduce arrhythmogenic substrates, improve cardiac function, and promote remodeling in a diseased heart. In this review, we discuss the epigenetic features of gap junctions that regulate cardiac morphology and remodeling. We further discuss potential clinical applications of current knowledge of the structure and function of gap junctions. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Comparative Investigation of Postoperative Complications in Patients With Gastroesophageal Junction Cancer Treated With Preoperative Chemotherapy or Surgery Alone

    DEFF Research Database (Denmark)

    Achiam, M P; Jensen, L.B.; Larsson, H.

    2016-01-01

    complications of patients with cancer at the gastroesophageal junction treated with either neoadjuvant chemotherapy or surgery alone in patients from "The Danish Clinical Registry of Carcinomas of the Esophagus, the Gastro-Esophageal Junction and the Stomach." MATERIALS AND METHODS: A historical follow-up study......BACKGROUND AND AIM: Gastroesophageal junction cancer is one of the leading causes to cancer-related death and the prognosis is poor. However, progress has been made over the last couple of decades with the introduction of multimodality treatment and optimized surgery. Three-year survival rates have...... of Carcinomas of the Esophagus, the Gastro-Esophageal Junction and the Stomach. No difference was found in demographics between the two groups, except for alcohol consumption and a lower T and N stage in the surgery-only group, and no difference in complication rates was found. Furthermore, no variable...

  16. Ballistic transport in InSb Josephson junctions

    Science.gov (United States)

    Damasco, John Jeffrey; Gill, Stephen; Car, Diana; Bakkers, Erik; Mason, Nadya

    We present transport measurements on Josephson junctions consisting of InSb nanowires contacted by Al at various junction lengths. Junction behavior as a function of gate voltage, electric field, and magnetic field is discussed. We show that short junctions behave as 1D quantum wires, exhibiting quantized conductance steps. In addition, we show how Josephson behavior changes as transport evolves from ballistic to diffusive as a function of contact spacing.

  17. Dynamics near Resonance Junctions in Hamiltonian Systems

    CERN Document Server

    Goto, S; Goto, Shin-itiro; Nozaki, Kazuhiro

    1999-01-01

    An approximate Poincare map near equally strong multiple resonances is reduced by means the method of averaging. Near the resonance junction of three degrees of freedom, we find that some homoclinic orbits ``whiskers'' in single resonance lines survive and form nearly periodic orbits, each of which looks like a pair of homoclinic orbits.

  18. Cooling of suspended nanostructures with tunnel junctions

    OpenAIRE

    Koppinen, P. J.; Maasilta, I. J.

    2009-01-01

    We have investigated electronic cooling of suspended nanowires with SINIS tunnel junction coolers. The suspended samples consist of a free standing nanowire suspended by four narrow ($\\sim$ 200 nm) bridges. We have compared two different cooler designs for cooling the suspended nanowire. We demonstrate that cooling of the nanowire is possible with a proper SINIS cooler design.

  19. Polyphosphonium-based ion bipolar junction transistors.

    Science.gov (United States)

    Gabrielsson, Erik O; Tybrandt, Klas; Berggren, Magnus

    2014-11-01

    Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e., ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example, addressable drug-delivery devices.

  20. Flux interactions on stacked Josephson junctions

    DEFF Research Database (Denmark)

    Scott, Alwyn C.; A., Petraglia

    1996-01-01

    Perturbation methods are used to study the dynamics of locked fluxon modes on stacked Josephson junctions and single crystals of certain high-T-c, superconductors. Two limiting cases are considered: (i) The nonlinear diffusion regime in which fluxon dynamics are dominated by energy exchange betwe...

  1. Defect formation in long Josephson junctions

    DEFF Research Database (Denmark)

    Gordeeva, Anna; Pankratov, Andrey

    2010-01-01

    We study numerically a mechanism of vortex formation in a long Josephson junction within the framework of the one-dimensional sine-Gordon model. This mechanism is switched on below the critical temperature. It is shown that the number of fluxons versus velocity of cooling roughly scales according...

  2. Gap junctions-guards of excitability

    DEFF Research Database (Denmark)

    Stroemlund, Line Waring; Jensen, Christa Funch; Qvortrup, Klaus;

    2015-01-01

    Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances...

  3. Fluxon density waves in long Josephson junctions

    DEFF Research Database (Denmark)

    Olsen, O. H.; Ustinov, A. V.; Pedersen, Niels Falsig

    1993-01-01

    Numerical simulations of the multiple fluxon dynamics stimulated by an external oscillating force applied at a boundary of a long Josephson junction are presented. The calculated IV characteristics agree well with a recent experimental observation of rf-induced satellite flux-flow steps. The volt...... density waves....

  4. Transmembrane potentials of canine AV junctional tissues.

    Science.gov (United States)

    Tse, W W

    1986-06-01

    The atrioventricular (AV) junction comprises the AV node, His bundle (HB), and specialized tissues proximal to the node called paranodal fibers (PNF). In the present study, an in vitro, dissection-exposed canine right atrial (RA), transitional fiber (TF), AV junctional preparation was used. The TF and PNF formed a pathway running along the base of the septal cusp of the tricuspid valve (SCTV). In the first experiment, impulses elicited at the RA were monitored to propagate sequentially through the TF, PNF, AV node, and then the HB. This functional evidence supports the concept that a conduction pathway connecting the RA and the AV node exists along the base of the SCTV. This internodal pathway is referred to as the septal cusp pathway. In another experiment, transmembrane potentials and Vmax were determined on each of the AV junctional tissues. Results showed that PNF had the lowest Vmax (2.5 V/sec), followed by AV node (7.0 V/sec) and HB (33 V/sec). This finding showed that PNF, and not the AV node, has the lowest Vmax, suggesting that the PNF has the lowest conductivity among the AV junctional tissues, and this study advances our understanding on the mechanism of AV conduction delay in dog hearts.

  5. Lateral junction dynamics lead the way out.

    Science.gov (United States)

    Behrndt, Martin; Heisenberg, Carl-Philipp

    2014-02-01

    Epithelial cell layers need to be tightly regulated to maintain their integrity and correct function. Cell integration into epithelial sheets is now shown to depend on the N-WASP-regulated stabilization of cortical F-actin, which generates distinct patterns of apical-lateral contractility at E-cadherin-based cell-cell junctions.

  6. Soliton excitations in Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Lomdahl, P. S.; Sørensen, O. H.; Christiansen, Peter Leth

    1982-01-01

    on the Nth ZFS yields the frequency Nf1 Coexistence of two adjacent frequencies is found on the third ZFS of the longer junction (L / λJ=6) in a narrow range of bias current as also found in the experiments. Small asymmetries in the experimental environment, a weak magnetic field, e.g., is introduced via...

  7. Fluxon Dynamics in Elliptic Annular Josephson Junctions

    DEFF Research Database (Denmark)

    Monaco, Roberto; Mygind, Jesper

    2016-01-01

    We analyze the dynamics of a magnetic flux quantum (current vortex) trapped in a current-biased long planar elliptic annular Josephson tunnel junction. The system is modeled by a perturbed sine-Gordon equation that determines the spatial and temporal behavior of the phase difference across the tu...

  8. Intercellular junctions in nerve-free hydra

    DEFF Research Database (Denmark)

    McDowall, A W; Grimmelikhuijzen, C J

    1980-01-01

    with particles in an "enplaque conformation appearing as a raised plateau on the E-face or as a depression on the P-face; (ii) structures morphologically similar to gap junctions in rat liver, containing particles on the P-face and corresponding pits on the E-face, both having hexagonal packing with a lattice...

  9. All-carbon molecular tunnel junctions.

    Science.gov (United States)

    Yan, Haijun; Bergren, Adam Johan; McCreery, Richard L

    2011-11-30

    This Article explores the idea of using nonmetallic contacts for molecular electronics. Metal-free, all-carbon molecular electronic junctions were fabricated by orienting a layer of organic molecules between two carbon conductors with high yield (>90%) and good reproducibility (rsd of current density at 0.5 V carbon devices exhibit current density-voltage (J-V) behavior similar to those with metallic Cu top contacts. However, the all-carbon devices display enhanced stability to bias extremes and greatly improved thermal stability. Completed carbon/nitroazobenzene(NAB)/carbon junctions can sustain temperatures up to 300 °C in vacuum for 30 min and can be scanned at ±1 V for at least 1.2 × 10(9) cycles in air at 100 °C without a significant change in J-V characteristics. Furthermore, these all-carbon devices can withstand much higher voltages and current densities than can Cu-containing junctions, which fail upon oxidation and/or electromigration of the copper. The advantages of carbon contacts stem mainly from the strong covalent bonding in the disordered carbon materials, which resists electromigration or penetration into the molecular layer, and provides enhanced stability. These results highlight the significance of nonmetallic contacts for molecular electronics and the potential for integration of all-carbon molecular junctions with conventional microelectronics.

  10. Mesh Currents and Josephson Junction Arrays

    OpenAIRE

    1995-01-01

    A simple but accurate mesh current analysis is performed on a XY model and on a SIMF model to derive the equations for a Josephson junction array. The equations obtained here turn out to be different from other equations already existing in the literature. Moreover, it is shown that the two models come from an unique hidden structure

  11. Gap junction protein connexin43 exacerbates lung vascular permeability.

    Directory of Open Access Journals (Sweden)

    James J O'Donnell

    Full Text Available Increased vascular permeability causes pulmonary edema that impairs arterial oxygenation and thus contributes to morbidity and mortality associated with Acute Respiratory Distress Syndrome and sepsis. Although components of intercellular adhesive and tight junctions are critical for maintaining the endothelial barrier, there has been limited study of the roles of gap junctions and their component proteins (connexins. Since connexins can modulate inflammatory signaling in other systems, we hypothesized that connexins may also regulate pulmonary endothelial permeability. The relationships between connexins and the permeability response to inflammatory stimuli were studied in cultured human pulmonary endothelial cells. Prolonged treatment with thrombin, lipopolysaccharide, or pathological cyclic stretch increased levels of mRNA and protein for the major connexin, connexin43 (Cx43. Thrombin and lipopolysaccharide both increased intercellular communication assayed by transfer of microinjected Lucifer yellow. Although thrombin decreased transendothelial resistance in these cells, the response was attenuated by pretreatment with the connexin inhibitor carbenoxolone. Additionally, the decreases of transendothelial resistance produced by either thrombin or lipopolysaccharide were attenuated by reducing Cx43 expression by siRNA knockdown. Both carbenoxolone and Cx43 knockdown also abrogated thrombin-induced phosphorylation of myosin light chain. Taken together, these data suggest that increased lung vascular permeability induced by inflammatory conditions may be amplified via increased expression of Cx43 and intercellular communication among pulmonary endothelial cells.

  12. Large negative differential conductance in single-molecule break junctions.

    Science.gov (United States)

    Perrin, Mickael L; Frisenda, Riccardo; Koole, Max; Seldenthuis, Johannes S; Gil, Jose A Celis; Valkenier, Hennie; Hummelen, Jan C; Renaud, Nicolas; Grozema, Ferdinand C; Thijssen, Joseph M; Dulić, Diana; van der Zant, Herre S J

    2014-10-01

    Molecular electronics aims at exploiting the internal structure and electronic orbitals of molecules to construct functional building blocks. To date, however, the overwhelming majority of experimentally realized single-molecule junctions can be described as single quantum dots, where transport is mainly determined by the alignment of the molecular orbital levels with respect to the Fermi energies of the electrodes and the electronic coupling with those electrodes. Particularly appealing exceptions include molecules in which two moieties are twisted with respect to each other and molecules in which quantum interference effects are possible. Here, we report the experimental observation of pronounced negative differential conductance in the current-voltage characteristics of a single molecule in break junctions. The molecule of interest consists of two conjugated arms, connected by a non-conjugated segment, resulting in two coupled sites. A voltage applied across the molecule pulls the energy of the sites apart, suppressing resonant transport through the molecule and causing the current to decrease. A generic theoretical model based on a two-site molecular orbital structure captures the experimental findings well, as confirmed by density functional theory with non-equilibrium Green's functions calculations that include the effect of the bias. Our results point towards a conductance mechanism mediated by the intrinsic molecular orbitals alignment of the molecule.

  13. Zero-voltage nondegenerate parametric mode in Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig

    1976-01-01

    A new parametric mode in a Josephson tunnel junction biased in the zero-voltage mode is suggested. It is a nondegenerate parametric excitation where the junction plasma resonance represents the input circuit, and a junction geometrical resonance represents the idler circuit. This nondegenerate mo...... for such a coupling. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  14. Systematic study of shallow junction formation on germanium substrates

    DEFF Research Database (Denmark)

    Hellings, Geert; Rosseel, Erik; Clarysse, Trudo

    2011-01-01

    Published results on Ge junctions are benchmarked systematically using RS–XJ plots. The electrical activation level required to meet the ITRS targets is calculated. Additionally, new results are presented on shallow furnace-annealed B junctions and shallow laser-annealed As junctions. Co-implanti...

  15. Long Josephson Junction Stack Coupled to a Cavity

    DEFF Research Database (Denmark)

    Madsen, Søren Peder; Pedersen, Niels Falsig; Groenbech-Jensen, N.

    2007-01-01

    A stack of inductively coupled long Josephson junctions are modeled as a system of coupled sine-Gordon equations. One boundary of the stack is coupled electrically to a resonant cavity. With one fluxon in each Josephson junction, the inter-junction fluxon forces are repulsive. We look at a possible...

  16. Structure Stability of Ⅰ-Type Carbon Nanotube Junctions

    Institute of Scientific and Technical Information of China (English)

    夏丹; 袁喆; 李家明

    2002-01-01

    Carbon nanotubes with junctions may play an important role in future ‘nanoelectronics' and future ‘nano devices'.In particular, junctions constructed with metal and semiconducting nanotubes have potential applications. Basedon the orthogonal tight-binding molecular dynamics method, we present our study of the structure stability ofI-type carbon nanotube junctions.

  17. Vacuum Tight Threaded Junctions (VTTJ): A new solution for reliable heterogeneous junctions in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Agostinetti, P., E-mail: piero.agostinetti@igi.cnr.it; Palma, M. Dalla; Agostini, F. Degli; Marcuzzi, D.; Rizzolo, A.; Rossetto, F.; Sonato, P.; Zaccaria, P.

    2015-10-15

    Highlights: • Heterogeneous junctions represent a critical issue in Nuclear Fusion experiments. • We have developed a new technique for heterogeneous junctions, called VTTJ, whose main advantages are low cost, high reliability and easiness of construction. • The VTTJ junctions have passed all the tests required by ITER for the heterogeneous junctions of the divertor. • Further tests have demonstrated wide margins for operation (up to 700 °C and 500 bar). - Abstract: A new technique, called Vacuum Tight Threaded Junction (VTTJ), has been developed and patented by Consorzio RFX, permitting to obtain low-cost and reliable non-welded junctions, able to maintain vacuum tightness also in heavy loading conditions (high temperature and high mechanical loads). The technique can be applied also if the materials to be joint are not weldable and for heterogeneous junctions (for example, between steel and copper) and has been tested up to 500 bar internal pressure and up to 700 °C, showing excellent leak tightness in vacuum conditions and high mechanical resistance. The main advantages with respect to existing technologies (for example, friction welding and electron beam welding) are an easy construction, a low cost, a precise positioning of the junction and a high repeatability of the process. Due to these advantages, the new technique has been adopted for several components of the SPIDER experiment and it is proposed for ITER, in particular for the ITER Heat and Current Drive Neutral Beam Injector and for its prototype, the MITICA experiment, to be tested at Consorzio RFX. This paper gives a detailed description of the VTTJ technique, of the samples manufactured and of the qualification tests that have been carried out so far.

  18. Graphene junction field-effect transistor

    Science.gov (United States)

    Ou, Tzu-Min; Borsa, Tomoko; van Zeghbroeck, Bart

    2014-03-01

    We have demonstrated for the first time a novel graphene transistor gated by a graphene/semiconductor junction rather than an insulating gate. The transistor operates much like a semiconductor junction Field Effect Transistor (jFET) where the depletion layer charge in the semiconductor modulates the mobile charge in the channel. The channel in our case is the graphene rather than another semiconductor layer. An increased reverse bias of the graphene/n-silicon junction increases the positive charge in the depletion region and thereby reduces the total charge in the graphene. We fabricated individual graphene/silicon junctions as well as graphene jFETs (GjFETs) on n-type (4.5x1015 cm-3) silicon with Cr/Au electrodes and 3 μm gate length. As a control device, we also fabricated back-gated graphene MOSFETs using a 90nm SiO2 on a p-type silicon substrate (1019 cm-3) . The graphene was grown by APCVD on copper foil and transferred with PMMA onto the silicon substrate. The GjFET exhibited an on-off ratio of 3.75, an intrinsic graphene doping of 1.75x1012 cm-2, compared to 1.17x1013 cm-2 in the MOSFET, and reached the Dirac point at 13.5V. Characteristics of the junctions and transistors were measured as a function of temperature and in response to light. Experimental data and a comparison with simulations will be presented.

  19. On the relevance of low side flows for thermal loads in T-junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zboray, Robert, E-mail: robert.zboray@psi.ch [Nuclear Energy and Safety Research Department, Laboratory for Thermal-hydraulics, Paul Scherrer Institute, CH-5232 Villigen-PSI (Switzerland); Prasser, Horst-Michael [Nuclear Energy and Safety Research Department, Laboratory for Thermal-hydraulics, Paul Scherrer Institute, CH-5232 Villigen-PSI (Switzerland); Swiss Federal Institute of Technology Zuerich, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zuerich (Switzerland)

    2011-08-15

    Highlights: > Turbulent mixing of fluid in a T-junction is investigated being relevant for thermal fatigue. > Special case of extremely low side flows (leakage flows) are studied. > High spatial and time resolution results are obtained using wire mesh sensors. > Entrainment into side branch occurs at very low side flows, which disappears above a critical side flow rate. > Entrainment causes significant low-frequency oscillations in the side branch potentially dangerous to induce thermal fatigue. - Abstract: The mixing of coolant streams of different temperatures in pipe junctions leads to temperature fluctuations that may cause thermal fatigue in the pipe wall. Numerous T-junction experiments are known from literature, which were performed to study the nature of thermal loads in the pipe walls occurring during the mixing of hot and cold liquid. It is common to all known experiments that the experimental boundary conditions are set to reflect cases, in which the flow velocities in both main and side branches of the T-junctions are of the same order of magnitude. In the present experiments, carried out using wire-mesh sensors, it was observed that very low flow velocities in the side branch compared to the main pipe may lead to conditions potentially severe for thermal fatigue due to the low frequency of the temperature fluctuations occurring. The T-junction presented here consists of a perpendicular connection of two pipes of 50 mm inner diameter. The straight and the side branches are supplied with water of different electrical conductivities, to enable performing generic, isothermal tests on turbulent mixing with the idea to model the temperature fluctuations in thermal mixing processes. A pair of wire-mesh sensors, each with a grid of 16 x 16 measuring points, are used to record conductivity distributions in the downstream of the T-junction as well as directly at the junction in both branches. At very low flow rates in the side branch, a characteristic

  20. Gap junctions and hemichannels composed of connexins: potential therapeutic targets for neurodegenerative diseases

    Directory of Open Access Journals (Sweden)

    Hideyuki eTakeuchi

    2014-09-01

    Full Text Available Microglia are macrophage-like resident immune cells that contribute to the maintenance of homeostasis in the central nervous system (CNS. Abnormal activation of microglia can cause damage in the CNS, and accumulation of activated microglia is a characteristic pathological observation in neurologic conditions such as trauma, stroke, inflammation, epilepsy, and neurodegenerative diseases. Activated microglia secrete high levels of glutamate, which damages CNS cells and has been implicated as a major cause of neurodegeneration in these conditions. Glutamate-receptor blockers and microglia inhibitors (e.g. minocycline have been examined as therapeutic candidates for several neurodegenerative diseases; however, these compounds exerted little therapeutic benefit because they either perturbed physiological glutamate signals or suppressed the actions of protective microglia. The ideal therapeutic approach would hamper the deleterious roles of activated microglia without diminishing their protective effects. We recently found that abnormally activated microglia secrete glutamate via gap-junction hemichannels on the cell surface. Moreover, administration of gap-junction inhibitors significantly suppressed excessive microglial glutamate release and improved disease symptoms in animal models of neurologic conditions such as stroke, multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer’s disease. Recent evidence also suggests that neuronal and glial communication via gap junctions amplifies neuroinflammation and neurodegeneration. Elucidation of the precise pathologic roles of gap junctions and hemichannels may lead to a novel therapeutic strategies that can slow and halt the progression of neurodegenerative diseases.

  1. When transcription goes on Holliday: Double Holliday junctions block RNA polymerase II transcription in vitro.

    Science.gov (United States)

    Pipathsouk, Anne; Belotserkovskii, Boris P; Hanawalt, Philip C

    2017-02-01

    Non-canonical DNA structures can obstruct transcription. This transcription blockage could have various biological consequences, including genomic instability and gratuitous transcription-coupled repair. Among potential structures causing transcription blockage are Holliday junctions (HJs), which can be generated as intermediates in homologous recombination or during processing of stalled replication forks. Of particular interest is the double Holliday junction (DHJ), which contains two HJs. Topological considerations impose the constraint that the total number of helical turns in the DNA duplexes between the junctions cannot be altered as long as the flanking DNA duplexes are intact. Thus, the DHJ structure should strongly resist transient unwinding during transcription; consequently, it is predicted to cause significantly stronger blockage than single HJ structures. The patterns of transcription blockage obtained for RNA polymerase II transcription in HeLa cell nuclear extracts were in accordance with this prediction. However, we did not detect transcription blockage with purified T7 phage RNA polymerase; we discuss a possible explanation for this difference. In general, our findings implicate naturally occurring Holliday junctions in transcription arrest. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Gap junctions and hemichannels composed of connexins: potential therapeutic targets for neurodegenerative diseases

    Science.gov (United States)

    Takeuchi, Hideyuki; Suzumura, Akio

    2014-01-01

    Microglia are macrophage-like resident immune cells that contribute to the maintenance of homeostasis in the central nervous system (CNS). Abnormal activation of microglia can cause damage in the CNS, and accumulation of activated microglia is a characteristic pathological observation in neurologic conditions such as trauma, stroke, inflammation, epilepsy, and neurodegenerative diseases. Activated microglia secrete high levels of glutamate, which damages CNS cells and has been implicated as a major cause of neurodegeneration in these conditions. Glutamate-receptor blockers and microglia inhibitors (e.g., minocycline) have been examined as therapeutic candidates for several neurodegenerative diseases; however, these compounds exerted little therapeutic benefit because they either perturbed physiological glutamate signals or suppressed the actions of protective microglia. The ideal therapeutic approach would hamper the deleterious roles of activated microglia without diminishing their protective effects. We recently found that abnormally activated microglia secrete glutamate via gap-junction hemichannels on the cell surface. Moreover, administration of gap-junction inhibitors significantly suppressed excessive microglial glutamate release and improved disease symptoms in animal models of neurologic conditions such as stroke, multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer's disease. Recent evidence also suggests that neuronal and glial communication via gap junctions amplifies neuroinflammation and neurodegeneration. Elucidation of the precise pathologic roles of gap junctions and hemichannels may lead to a novel therapeutic strategies that can slow and halt the progression of neurodegenerative diseases. PMID:25228858

  3. Gap junctions and hemichannels composed of connexins: potential therapeutic targets for neurodegenerative diseases.

    Science.gov (United States)

    Takeuchi, Hideyuki; Suzumura, Akio

    2014-01-01

    Microglia are macrophage-like resident immune cells that contribute to the maintenance of homeostasis in the central nervous system (CNS). Abnormal activation of microglia can cause damage in the CNS, and accumulation of activated microglia is a characteristic pathological observation in neurologic conditions such as trauma, stroke, inflammation, epilepsy, and neurodegenerative diseases. Activated microglia secrete high levels of glutamate, which damages CNS cells and has been implicated as a major cause of neurodegeneration in these conditions. Glutamate-receptor blockers and microglia inhibitors (e.g., minocycline) have been examined as therapeutic candidates for several neurodegenerative diseases; however, these compounds exerted little therapeutic benefit because they either perturbed physiological glutamate signals or suppressed the actions of protective microglia. The ideal therapeutic approach would hamper the deleterious roles of activated microglia without diminishing their protective effects. We recently found that abnormally activated microglia secrete glutamate via gap-junction hemichannels on the cell surface. Moreover, administration of gap-junction inhibitors significantly suppressed excessive microglial glutamate release and improved disease symptoms in animal models of neurologic conditions such as stroke, multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer's disease. Recent evidence also suggests that neuronal and glial communication via gap junctions amplifies neuroinflammation and neurodegeneration. Elucidation of the precise pathologic roles of gap junctions and hemichannels may lead to a novel therapeutic strategies that can slow and halt the progression of neurodegenerative diseases.

  4. Remodeling of gap junctions in ischemic and nonischemic forms of heart disease.

    Science.gov (United States)

    Saffitz, Jeffrey E; Hames, Kiyomi Yamada; Kanno, Shigeto

    2007-08-01

    Electrical activation of the myocardium to produce effective pumping of blood depends on the orderly coordinated spatial and temporal transfer of current from one cell to another via gap junctions. Normal ventricular myocytes are extensively coupled by gap junctions and have the capacity to rapidly increase the amount of connexin within gap junction plaques to meet physiological demands for enhanced cell-cell communication. However, myocytes can also rapidly uncouple in response to injury or disease. In general, both acute and chronic forms of heart disease caused by diverse etiologies are associated with changes in the expression of connexins and remodeling of gap junctions. Such remodeling may have both adaptive and maladaptive consequences and contribute to major clinical processes such as heart failure and sudden cardiac death. Our laboratory has investigated mechanisms regulating cell-cell electrical coupling in the heart under physiological and pathophysiological conditions. This review is focused on selected aspects of this work pertaining to changes in coupling in response to acute and chronic ischemic heart disease and in familial cardiomyopathies caused by mutations in genes encoding desmosomal proteins.

  5. Grainy head promotes expression of septate junction proteins and influences epithelial morphogenesis.

    Science.gov (United States)

    Narasimha, Maithreyi; Uv, Anne; Krejci, Alena; Brown, Nicholas H; Bray, Sarah J

    2008-03-15

    Transcription factors of the Grainy head (Grh) family are required in epithelia to generate the impermeable apical layer that protects against the external environment. This function is conserved in vertebrates and invertebrates, despite the differing molecular composition of the protective barrier. Epithelial cells also have junctions that create a paracellular diffusion barrier (tight or septate junctions). To examine whether Grh has a role in regulating such characteristics, we used an epidermal layer in the Drosophila embryo that has no endogenous Grh and lacks septate junctions, the amnioserosa. Expression of Grh in the amnioserosa caused severe defects in dorsal closure, a process similar to wound closure, and induced robust expression of the septate junction proteins Coracle, Fasciclin 3 and Sinuous. Grh-binding sites are present within the genes encoding these proteins, consistent with them being direct targets. Removal of Grh from imaginal disc cells caused a reduction in Fasciclin 3 and Coracle levels, suggesting that Grh normally fine tunes their epithelial expression and hence contributes to barrier properties. The fact that ectopic Grh arrests dorsal closure also suggests that this dynamic process relies on epithelia having distinct adhesive properties conferred by differential deployment of Grh.

  6. Planar Josephson tunnel junctions in a transverse magnetic field

    DEFF Research Database (Denmark)

    Monacoa, R.; Aarøe, Morten; Mygind, Jesper

    2007-01-01

    Traditionally, since the discovery of the Josephson effect in 1962, the magnetic diffraction pattern of planar Josephson tunnel junctions has been recorded with the field applied in the plane of the junction. Here we discuss the static junction properties in a transverse magnetic field where...... demagnetization effects imposed by the tunnel barrier and electrodes geometry are important. Measurements of the junction critical current versus magnetic field in planar Nb-based high-quality junctions with different geometry, size, and critical current density show that it is advantageous to use a transverse...

  7. The computation of first order moments on junction trees

    CERN Document Server

    Djuric, Milos B; Stankovic, Miomir S

    2012-01-01

    We review some existing methods for the computation of first order moments on junction trees using Shafer-Shenoy algorithm. First, we consider the problem of first order moments computation as vertices problem in junction trees. In this way, the problem is solved using the memory space of an order of the junction tree edge-set cardinality. After that, we consider two algorithms, Lauritzen-Nilsson algorithm, and Mau\\'a et al. algorithm, which computes the first order moments as the normalization problem in junction tree, using the memory space of an order of the junction tree leaf-set cardinality.

  8. MoRe-based and MgB{sub 2} -based tunnel junctions and their characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Shaternik, V; Noskov, V; Chubatyy, V [Kurdyumov Institute for Metal Physics of National Academy of Sciences of Ukraine, Vernadskii boulevard 36, 02142 Kiev (Ukraine); Larkin, S [Concern ' Nauka' , Dovnar-Zapol' skii street 2/20, 03116 Kiev (Ukraine); Belogolovskii, M, E-mail: shaternik@mail.r [Donetsk Institute for Physics and Engineering, National Academy of Sciences of Ukraine, 83114 Donetsk (Ukraine)

    2010-06-01

    Perspective Josephson Mo-Re alloy-oxide-Pb, MgB{sub 2}- oxide - Mo-Re alloy and Mo-Re alloy-normal metal-oxide- normal metal-Mo-Re alloy junctions have been fabricated and investigated. Thin ({approx}50-100 nm) MoRe superconducting films are deposited on Al{sub 2}O{sub 3} substrates by using a dc magnetron sputtering of MoRe target. Thin ({approx}50-100 nm) MgB{sub 2} superconducting films are deposited on Al{sub 2}O{sub 3} substrates by using e-beam evaporation of boron and thermal coevaporation of magnesium. To investigate a transparency spread for the fabricated junctions barriers the computer simulation of the measured quasiparticle I-V curves have been done in framework of the model of multiple Andreev reflections in double-barrier junction interfaces. It's demonstrated the investigated junctions can be described as highly asymmetric double-barrier Josephson junctions with great difference between the two barrier transparencies. Results of computer simulation of quasiparticles I-V curves of junctions are presented and discussed. The I{sub C}(T) characteristics, measured for Josephson heterostructures with different thickness of metal layer s and exposure dose E, essentially deviate from an Ambegaokar- Baratoff (A and B) I{sub C}(T) behavior and Kulik-Omelianchuck (K and O) curves, because of proximity effect caused by the comparatively high value of s (up to 100 nm).

  9. Distal Junctional Disease after Occipitothoracic Fusion for Rheumatoid Cervical Disorders: Correlation with Cervical Spine Sagittal Alignment.

    Science.gov (United States)

    Tanouchi, Tetsu; Shimizu, Takachika; Fueki, Keisuke; Ino, Masatake; Toda, Naofumi; Manabe, Nodoka; Itoh, Kanako

    2015-10-01

    Study Design Retrospective radiographic study. Objective We have performed occipitothoracic (OT) fusion for severe rheumatoid cervical disorders since 1991. In our previous study, we reported that the distal junctional disease occurred in patients with fusion of O-T4 or longer due to increased mechanical stress. The present study further evaluated the association between the distal junctional disease and the cervical spine sagittal alignment. Methods Among 60 consecutive OT fusion cases between 1991 and 2010, 24 patients who underwent O-T5 fusion were enrolled in this study. The patients were grouped based on whether they developed postoperative distal junctional disease (group F) or not (group N). We measured pre- and postoperative O-C2, C2-C7, and O-C7 angles and evaluated the association between these values and the occurrence of distal junctional disease. Results Seven (29%) of 24 patients developed adjacent-level vertebral fractures as distal junctional disease. In group F, the mean pre- and postoperative O-C2, C2-C7, and O-C7 angles were 12.1 and 16.8, 7.2 and 11.2, and 19.4 and 27.9 degrees, respectively. In group N, the mean pre- and postoperative O-C2, C2-C7, and O-C7 angles were 15.9 and 15.0, 4.9 and 5.8, and 21.0 and 20.9 degrees, respectively. There were no significant differences between the two groups. The difference in the O-C7 angle (postoperative angle - preoperative angle) in group F was significantly larger than that in group N (p = 0.04). Conclusion Excessive correction of the O-C7 angle (hyperlordotic alignment) is likely to cause postoperative distal junctional disease following the OT fusion.

  10. Spectrum of Lesions Affecting the Renal Pelvis and Pelviureteric Junction: A 13-Year Retrospective Analysis

    Science.gov (United States)

    Kini, Hema; Suresh, Pooja Kundapur; Guni, Laxman Prabhu Gurupur; Bhat, Shaila; Kini, Jyoti Ramanath

    2016-01-01

    Introduction Both, the renal pelvis and the ureter, are affected by developmental, reactive and neoplastic disorders, though rare in incidence. Aim This series of cases were analysed to study the clinicopathological characteristics of the common and comparatively rare lesions involving the renal pelvis and pelviureteric junction. Materials and Methods A retrospective collection of 476 nephrectomies and pelviureteric junction resections, received over a period of 13 years from 2001 to 2013 was done. The patients’ clinical details were obtained and the histopathological findings reviewed. The lesions were classified into non-neoplastic and neoplastic categories. Results Primary involvement of the renal pelvis and pelviureteric junction was seen in 105 of 476 specimens. The mean age was 54.5 years with a male to female ratio of 2.2:1. The non-neoplastic lesions accounted for 76.2% of cases with a majority being pelviureteric junction obstruction due to inflammation induced fibromuscular hypertrophy (68.6%) causing hydronephrosis. Urothelial carcinomas were encountered in 20% of the cases. A majority of the urothelial carcinomas were infiltrative (81%) and high grade (71%) tumours. Conclusion Renal pelvis, a conduit to propel urine, can be the site for numerous disorders. Non-neoplastic lesions were more common than neoplasms. Pelviureteric junction obstruction due to inflammation induced fibromuscular hypertrophy was the commonest lesion in our study. In the neoplastic category, urothelial carcinoma was most common. However, rare lesions such as hamartomatous fibroepithelial polyp, Von Brunn’s nests, flat urothelial hyperplasia and intramuscular haemangioma of upper ureter at the pelviureteric junction were encountered along with occasional cases of tuberculosis and squamous cell carcinomas. PMID:27042468

  11. Connexin26 regulates assembly and maintenance of cochlear gap junction macromolecular complex for normal hearing

    Science.gov (United States)

    Kamiya, Kazusaku; Fukunaga, Ichiro; Hatakeyama, Kaori; Ikeda, Katsuhisa

    2015-12-01

    Hereditary deafness affects about 1 in 2000 children and GJB2 gene mutation is most frequent cause for this disease in the world. GJB2 encodes connexin26 (Cx26), a component in cochlear gap junction. Recently, we found macromolecular change of gap junction plaques with two different types of Cx26 mutation as major classification of clinical case, one is a model of dominant negative type, Cx26R75W+ and the other is conditional gene deficient mouse, Cx26f/fP0Cre as a model for insufficiency of gap junction protein [6]. Gap junction composed mainly of Cx26 and Cx30 in wild type mice formed large planar gap junction plaques (GJP). In contrast, Cx26R75W+ and Cx26f/fP0Cre showed fragmented small round GJPs around the cell border. In Cx26f/fP0Cre, some of the cells with Cx26 expression due to their cellular mosaicism showed normal large GJP with Cx26 and Cx30 only at the cell junction site between two Cx26 positive cells. These indicate that bilateral Cx26 expressions from both adjacent cells are essential for the formation of the cochlear linear GJP, and it is not compensated by other cochlear Connexins such as Connexin30. In the present study, we demonstrated a new molecular pathology in most common hereditary deafness with different types of Connexin26 mutations, and this machinery can be a new target for drag design of hereditary deafness.

  12. Down-regulation of membrana granulosa cell gap junctions is correlated with irreversible commitment to resume meiosis in golden Syrian hamster oocytes.

    Science.gov (United States)

    Racowsky, C; Baldwin, K V; Larabell, C A; DeMarais, A A; Kazilek, C J

    1989-08-01

    One of the currently popular hypotheses for the regulation of meiotic resumption in mammalian oocytes proposes that the preovulatory surge of luteinizing hormone causes down-regulation of follicular gap junctions, which in turn disrupts transfer of a meiotic arrester from the somatic cells into the oocyte. The present study has investigated this hypothesis by examining the integrity of membrana granulosa cell gap junctions during the period of irreversible commitment to maturation of golden Syrian hamster oocytes in vivo. Our results have revealed a significant progressive decrease in the fractional area of cell surface occupied by gap junction membrane with increasing percentage of oocytes irreversibly committed to mature (1.946% and 0.921% fractional gap junction area at 0% and 100% oocytes irreversibly committed to mature, respectively, P less than 0.05). This net loss of membrana granulosa cell gap junctions from the cell surface was accompanied by a significant decrease in density of gap junction particles, whether they were arranged in rectilinear or non-rectilinear packing patterns. Furthermore, the number of gap junction particles per unit area of surface membrane scanned also underwent a significant progressive decrease with increasing percentage of oocytes irreversibly committed to mature. These data with the hamster are consistent with the hypothesis that down-regulation of membrana granulosa cell gap junctions may be of central importance in the regulation of gonadotropic stimulation of meiotic resumption in mammalian oocytes.

  13. The glomerulo-tubular junction: a target in renal diseases.

    Science.gov (United States)

    Lindop, G B M; Gibson, I W; Downie, T T; Vass, D; Cohen, E P

    2002-05-01

    Both global and segmental glomerulopathies may damage specific areas of the renal glomerulus. Diseases associated with glomerular hyperperfusion cause lesions at the vascular pole, while diseases associated with proteinuria often damage the tubular pole. Atubular glomeruli are now known to be plentiful in a variety of common renal diseases. These glomeruli are disconnected from their tubule at the tubular pole and therefore cannot participate in the production of urine. It is widely believed that the disconnection is a result of external compression by periglomerular fibrosis. However, the variable anatomy and cell populations within both the glomerulus and the beginning of the proximal tubule at the glomerulo-tubular junction may also have important roles to play in the response to damage at this sensitive site of the nephron.

  14. Recovery by triple junction motion in heavily deformed metals

    DEFF Research Database (Denmark)

    Yu, Tianbo; Hansen, Niels; Huang, Xiaoxu

    2015-01-01

    A number of processes may occur during recovery, which reduce the stored energy and coarsen the structure, paving the way for the nucleation of recrystallization. In this review, recovery is discussed based on the initial deformed structure. Recovery in samples deformed to low-to-medium strains...... is briefly considered, whereas recovery in samples deformed to much higher strains is discussed in more detail. An example is Al, where a new and important recovery mechanism is triple junction motion, which can remove thin lamellae and consequently increase the thickness of neighbouring lamellae....... This recovery mechanism therefore coarsens the structure and causes a gradual transition from a lamellar to a near equiaxed structure preceding recrystallization. This mechanism is discussed in conjunction with structural pinning, which stabilizes the coarsening microstructure, thereby balancing the forces...

  15. Optimised Calibration Method for Six-Port Junction

    Institute of Scientific and Technical Information of China (English)

    XIONG Xiang-zheng; LIAO Cheng; XIAO Hua-qing

    2008-01-01

    A dual-tone technique is used to produce multi-samples in optimising calibration of six-port junction. More accurate results are achieved by using the least-square method and excluding those samples which may cause bigger errors. A 0.80 1.10 GHz microwave integrated circuit (MIC) six-port reflectometer is constructed. Nine test samples are used in the measurement. With Engens calibration procedure, the difference between the HP8510 and the six-port reflectrometer is in the order of 0.20 dB/1.5° for most cases, above 0.50 dB/5.0° at boundary frequency . With the optimised method, the difference is less than 0.10 dB/1.0° for most cases, and the biggest error is 0.42 dB/2.1° for boundary frequencies.

  16. String networks with junctions in competition models

    Science.gov (United States)

    Avelino, P. P.; Bazeia, D.; Losano, L.; Menezes, J.; de Oliveira, B. F.

    2017-03-01

    In this work we give specific examples of competition models, with six and eight species, whose three-dimensional dynamics naturally leads to the formation of string networks with junctions, associated with regions that have a high concentration of enemy species. We study the two- and three-dimensional evolution of such networks, both using stochastic network and mean field theory simulations. If the predation, reproduction and mobility probabilities do not vary in space and time, we find that the networks attain scaling regimes with a characteristic length roughly proportional to t 1 / 2, where t is the physical time, thus showing that the presence of junctions, on its own, does not have a significant impact on their scaling properties.

  17. Vibrational Heat Transport in Molecular Junctions

    Science.gov (United States)

    Segal, Dvira; Agarwalla, Bijay Kumar

    2016-05-01

    We review studies of vibrational energy transfer in a molecular junction geometry, consisting of a molecule bridging two heat reservoirs, solids or large chemical compounds. This setup is of interest for applications in molecular electronics, thermoelectrics, and nanophononics, and for addressing basic questions in the theory of classical and quantum transport. Calculations show that system size, disorder, structure, dimensionality, internal anharmonicities, contact interaction, and quantum coherent effects are factors that combine to determine the predominant mechanism (ballistic/diffusive), effectiveness (poor/good), and functionality (linear/nonlinear) of thermal conduction at the nanoscale. We review recent experiments and relevant calculations of quantum heat transfer in molecular junctions. We recount the Landauer approach, appropriate for the study of elastic (harmonic) phononic transport, and outline techniques that incorporate molecular anharmonicities. Theoretical methods are described along with examples illustrating the challenge of reaching control over vibrational heat conduction in molecules.

  18. String networks with junctions in competition models

    CERN Document Server

    Avelino, P P; Losano, L; Menezes, J; de Oliveira, B F

    2016-01-01

    In this work we give specific examples of competition models, with six and eight species, whose three-dimensional dynamics naturally leads to the formation of string networks with junctions, associated with regions that have a high concentration of enemy species. We study the two- and three-dimensional evolution of such networks, both using stochastic network and mean field theory simulations. If the predation, reproduction and mobility probabilities do not vary in space and time, we find that the networks attain scaling regimes with a characteristic length roughly proportional to $t^{1/2}$, where $t$ is the physical time, thus showing that the presence of junctions, on its own, does not have a significant impact on their scaling properties.

  19. Junction between surfaces of two topological insulators

    Science.gov (United States)

    Sen, Diptiman; Deb, Oindrila

    2012-02-01

    We study scattering from a line junction which separates the surfaces of two three-dimensional topological insulators; some aspects of this problem were recently studied in Takahashi and Murakami, Phys. Rev. Lett. 107, 166805 (2011). The velocities of the Dirac electrons on the two surfaces may be unequal and may even have opposite signs; in the latter case, we find that the electrons must, in general, go into the two-dimensional interface separating the two topological insulators. We also study what happens if the two surfaces are at an angle φ with respect to each other. We find in this case that there are bound states which propagate along the line junction with a velocity and direction of spin which depend on the bending angle φ.

  20. Boson Josephson Junction with Trapped Atoms

    Science.gov (United States)

    Raghavan, S.; Smerzi, A.; Fantoni, S.; Shenoy, S. R.

    We consider coherent atomic tunneling between two weakly coupled Bose-Einstein condensates at T=0 in a double-well trap. The condensate dynamics of the macroscopic amplitudes in the two wells is modeled by two Gross-Pitaevskii equations (GPE) coupled by a tunneling matrix element. Analytic elliptic function solutions are obtained for the time evolution of the inter-well fractional population imbalance z(t) (related to the condensate phase difference) of the Boson Josephson junction (BJJ). Surprisingly, the neutral-atom BJJ shows (non-sinusoidal generalizations of) effects seen in charged-electron superconductor Josephson junctions (SJJ). The BJJ elliptic-function behavior has a singular dependence on a GPE parameter ratio Λ at a critical ratio Λ=Λc, beyond which a novel 'macroscopic quantum self-trapping' effect sets in with a non-zero time-averaged imbalance ≠0.

  1. Non-Lagrangian theories from brane junctions

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Ling [Chalmers Univ. of Technology, Goeteborg (Sweden); Mitev, Vladimir [Humboldt Univ., Berlin (Germany). Inst. fuer Mathematik und Inst. fuer Physik; Pomoni, Elli [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Taki, Masato [RIKEN Nishina Center, Saitama (Japan). Mathematical Physics Lab.; Yagi, Futoshi [International School of Advanced Studies (SISSA), Trieste (Italy); INFN, Trieste (Italy); Korea Institute for Advanced Study (KIAS), Seoul (Korea, Republic of)

    2013-10-15

    In this article we use 5-brane junctions to study the 5D T{sub N} SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W{sub N} Toda theories.

  2. Electron transport in doped fullerene molecular junctions

    Science.gov (United States)

    Kaur, Milanpreet; Sawhney, Ravinder Singh; Engles, Derick

    The effect of doping on the electron transport of molecular junctions is analyzed in this paper. The doped fullerene molecules are stringed to two semi-infinite gold electrodes and analyzed at equilibrium and nonequilibrium conditions of these device configurations. The contemplation is done using nonequilibrium Green’s function (NEGF)-density functional theory (DFT) to evaluate its density of states (DOS), transmission coefficient, molecular orbitals, electron density, charge transfer, current, and conductance. We conclude from the elucidated results that Au-C16Li4-Au and Au-C16Ne4-Au devices behave as an ordinary p-n junction diode and a Zener diode, respectively. Moreover, these doped fullerene molecules do not lose their metallic nature when sandwiched between the pair of gold electrodes.

  3. Charge Transport Phenomena in Peptide Molecular Junctions

    Directory of Open Access Journals (Sweden)

    Alessandra Luchini

    2008-01-01

    Full Text Available Inelastic electron tunneling spectroscopy (IETS is a valuable in situ spectroscopic analysis technique that provides a direct portrait of the electron transport properties of a molecular species. In the past, IETS has been applied to small molecules. Using self-assembled nanoelectronic junctions, IETS was performed for the first time on a large polypeptide protein peptide in the phosphorylated and native form, yielding interpretable spectra. A reproducible 10-fold shift of the I/V characteristics of the peptide was observed upon phosphorylation. Phosphorylation can be utilized as a site-specific modification to alter peptide structure and thereby influence electron transport in peptide molecular junctions. It is envisioned that kinases and phosphatases may be used to create tunable systems for molecular electronics applications, such as biosensors and memory devices.

  4. Peltier Junction heats and cools car seat

    Energy Technology Data Exchange (ETDEWEB)

    Gottschalk, M.A.

    1994-10-10

    Electrically heated seats may soon become heated and cooled seats. The design called the CCS module exploits the heat-pump capability of a class of semiconductor thermoelectric devices (TEDs) known as Peltier Junction. Every CCS module contain two TEDs. Heating and cooling occurs through convection and conduction. The heart of the system is the thermoelectric heat pump. This is originally conceived as the sole heating/cooling options for a prototype electric vehicle.

  5. Josephson junction microwave modulators for qubit control

    Science.gov (United States)

    Naaman, O.; Strong, J. A.; Ferguson, D. G.; Egan, J.; Bailey, N.; Hinkey, R. T.

    2017-02-01

    We demonstrate Josephson junction based double-balanced mixer and phase shifter circuits operating at 6-10 GHz and integrate these components to implement both a monolithic amplitude/phase vector modulator and an I/Q quadrature mixer. The devices are actuated by flux signals, dissipate no power on chip, exhibit input saturation powers in excess of 1 nW, and provide cryogenic microwave modulation solutions for integrated control of superconducting qubits.

  6. Internal dynamics of long Josephson junction oscillators

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Lomdahl, P. S.; Scott, Alwyn C.;

    1981-01-01

    Numerical computations on a sine-Gordon model of the Josephson junction fluxon oscillator are compared with experimental measurements. Good agreement is found for the voltage current characteristic, oscillator power output, and range of current bias over which oscillation is observed. Our numeric...... results imply a ''bunched-fluxon'' mode of oscillation at larger values of bias current. Applied Physics Letters is copyrighted by The American Institute of Physics....

  7. RADIOLOGICAL EVALUATION OF CRANIOVERTEBRAL JUNCTION ANOMALIES

    Directory of Open Access Journals (Sweden)

    Joji Reddy

    2015-08-01

    Full Text Available INTRODUCTION: Detailed discussions of the CVJ are conspicuously absent in many standard textbooks and chapters addressing the skull or cervical spine, since it lies in between these regions . CVJ anomalies are common in India subcontinent. OBJECTIVES : To outline the normal anatomy and various abnormalities of craniovertebral junction. To evaluate the most common developmental and acquired craniovertebral junction abnormalities . CRANIOMETRY AND DIAGNOSIS: Radiological evaluation of CVJ requir es identification of only a few anatomic structures. Over the years multiple lines , planes and angles have been described for assessment of CVJ relationship , initially with radiography and later with polytomography. Two lines have remained particularly use ful for evaluation of CVJ relationship with virtually any imaging modality: the chamberlain`s line and weckenheim ’ s clivus base line . Two angles also continue to be useful: the welcher basal angle and atlanto occipital joint axis angle. PATIENTS AND METHOD S: The prospective study of craniovertebral junction anomalies was carried out at Kurnool medical college , Governament general hospital Kurnool from NOV 2012 to AUG 2014. The patients are subjected to clinical evaluation and radiological evaluation. OBSERV ATIONS AND RESULTS : In our study there is male predominance with male to female ratio of 2:1 . Majority of patients are in the age group of 11 - 40 (73.26%. The commonest symptom seen is weakness of extremities ( 70% with associated numbness (50%. On clinica l examination pyramidal tract involvement noticed in 70% of cases. Basilar invagination is the most common followed by Atlantoocoipital assimilation (40% and AAD (30% . CONCLUSION : Computed tomography and magnetic resonance imaging are invalvable adjuncts to the plain radiographs in the evaluation of the craniovertebral junction anomalies. Chamberlain’s line and McGregor line are the most commonly applied craniometric measurements

  8. Interfacial capacitance effects in magnetic tunneling junctions

    CERN Document Server

    Landry, G; Du, J; Xiao, J Q

    2001-01-01

    We have investigated the AC transport properties of magnetic tunnel junctions (MTJ) in order to characterize interfacial properties. One such property is interfacial charge accumulation, which leads to a voltage drop in the electrodes of the MTJ and the measured capacitance differing from the geometrical capacitance. Through measurement of capacitance spectra, we have extracted an interfacial capacitance of 16 mu F/cm sup 2 per interface and a screening length of 0.55 A for FeNi electrodes.

  9. Gap junction channels and cardiac impulse propagation.

    Science.gov (United States)

    Desplantez, Thomas; Dupont, Emmanuel; Severs, Nicholas J; Weingart, Robert

    2007-08-01

    The role of gap junction channels on cardiac impulse propagation is complex. This review focuses on the differential expression of connexins in the heart and the biophysical properties of gap junction channels under normal and disease conditions. Structural determinants of impulse propagation have been gained from biochemical and immunocytochemical studies performed on tissue extracts and intact cardiac tissue. These have defined the distinctive connexin coexpression patterns and relative levels in different cardiac tissues. Functional determinants of impulse propagation have emerged from electrophysiological experiments carried out on cell pairs. The static properties (channel number and conductance) limit the current flow between adjacent cardiomyocytes and thus set the basic conduction velocity. The dynamic properties (voltage-sensitive gating and kinetics of channels) are responsible for a modulation of the conduction velocity during propagated action potentials. The effect is moderate and depends on the type of Cx and channel. For homomeric-homotypic channels, the influence is small to medium; for homomeric-heterotypic channels, it is medium to strong. Since no data are currently available on heteromeric channels, their influence on impulse propagation is speculative. The modulation by gap junction channels is most prominent in tissues at the boundaries between cardiac tissues such as sinoatrial node-atrial muscle, atrioventricular node-His bundle, His bundle-bundle branch and Purkinje fibers-ventricular muscle. The data predict facilitation of orthodromic propagation.

  10. Gap Junctions: The Claymore for Cancerous Cells

    Directory of Open Access Journals (Sweden)

    Ailar Nakhlband

    2011-07-01

    Full Text Available Introduction: Gap junctions play an important role in the cell proliferation in mammalian cells as well as carcinogenesis. However, there are controversial issues about their role in cancer pathogenesis. This study was designed to evaluate genotoxicity and cytotoxicity of Carbenoxolone (CBX as a prototype of inter-cellular gap junction blocker in MCF7 and BT20 human breast cancer cells. Methods: The MCF7and BT20 human breast cancer cell lines were cultivated, and treated at designated confluency with different doses of CBX. Cellular cytotoxicity was examined using standard colorimetric assay associated with cell viability tests. Gene expression evaluation was carried out using real time polymerase chain reaction (PCR. Results: MCF7 and BT20 cells were significantly affected by CBX in a dose dependent manner in cell viability assays. Despite varying expression of genes, down regulation of pro- and anti-apoptotic genes was observed in these cells. Conclusion: Based upon this investigation, it can be concluded that CBX could affect both low and high proliferative types of breast cancer cell lines and disproportionate down regulation of both pre- and anti-apoptotic genes may be related to interacting biomolecules, perhaps via gap junctions.

  11. Molecular beam epitaxy growth of germanium junctions for multi-junction solar cell applications

    Science.gov (United States)

    Masuda, T.; Faucher, J.; Lee, M. L.

    2016-11-01

    We report on the molecular beam epitaxy (MBE) growth and device characteristics of Ge solar cells. Integrating a Ge bottom cell beneath a lattice-matched triple junction stack grown by MBE could enable ultra-high efficiencies without metamorphic growth or wafer bonding. However, a diffused junction cannot be readily formed in Ge by MBE due to the low sticking coefficient of group-V molecules on Ge surfaces. We therefore realized Ge junctions by growth of homo-epitaxial n-Ge on p-Ge wafers within a standard III-V MBE system. We then fabricated Ge solar cells, finding growth temperature and post-growth annealing to be key factors for achieving high efficiency. Open-circuit voltage and fill factor values of ~0.175 V and ~0.59 without a window layer were obtained, both of which are comparable to diffused Ge junctions formed by metal-organic vapor phase epitaxy. We also demonstrate growth of high-quality, single-domain GaAs on the Ge junction, as needed for subsequent growth of III-V subcells, and that the surface passivation afforded by the GaAs layer slightly improves the Ge cell performance.

  12. Bilateral spontaneous pneumothorax secondary to aspiration pneumonia induced by a wristwatch lodged at the pharyngoesophageal junction.

    Science.gov (United States)

    Kawai, Chihiro; Miyao, Masashi; Kotani, Hirokazu; Tamaki, Keiji

    2015-06-01

    Bilateral spontaneous pneumothorax secondary to disease is rare and seldom encountered in forensic autopsies; however, traumatic bilateral pneumothorax occurs often. Herein, we present a forensic case involving a 50-year-old woman who died 4 days after ingesting a wristwatch. Postmortem computed tomography and autopsy findings demonstrated that the wristwatch was lodged at the pharyngoesophageal junction, that she had a bilateral pneumothorax unaccompanied by any thoracic wound, and that macular hemorrhagic lesions on the lung surfaces were responsible for the pneumothorax. A histological examination of the macular lesions revealed that they were aspiration pneumonia foci with many birefringent foreign materials. Furthermore, a necrotic process secondary to aspiration pneumonia with a one way check-valve hyperinflation caused by foreign materials in the bronchioles was the most probable pathogenesis of her pneumothorax. To our knowledge, this is the first reported case of a bilateral secondary spontaneous pneumothorax caused by a large foreign body at the pharyngoesophageal junction leading to death.

  13. The Cape Mendocino, California, earthquakes of April 1992: Subduction at the triple junction

    Science.gov (United States)

    Oppenheimer, D.; Beroza, G.; Carver, G.; Dengler, L.; Eaton, J.; Gee, L.; Gonzalez, F.; Jayko, A.; Li, W.H.; Lisowski, M.; Magee, M.; Marshall, G.; Murray, M.; McPherson, R.; Romanowicz, B.; Satake, K.; Simpson, R.; Somerville, P.; Stein, R.; Valentine, D.

    1993-01-01

    The 25 April 1992 magnitude 7.1 Cape Mendocino thrust earthquake demonstrated that the North America-Gorda plate boundary is seismogenic and illustrated hazards that could result from much larger earthquakes forecast for the Cascadia region. The shock occurred just north of the Mendocino Triple Junction and caused strong ground motion and moderate damage in the immediate area. Rupture initiated onshore at a depth of 10.5 kilometers and propagated up-dip and seaward. Slip on steep faults in the Gorda plate generated two magnitude 6.6 aftershocks on 26 April. The main shock did not produce surface rupture on land but caused coastal uplift and a tsunami. The emerging picture of seismicity and faulting at the triple junction suggests that the region is likely to continue experiencing significant seismicity.

  14. Impaired astrocytic gap junction coupling and potassium buffering in a mouse model of tuberous sclerosis complex.

    Science.gov (United States)

    Xu, Lin; Zeng, Ling-Hui; Wong, Michael

    2009-05-01

    Abnormalities in astrocytes occur in the brains of patients with Tuberous Sclerosis Complex (TSC) and may contribute to the pathogenesis of neurological dysfunction in this disease. Here, we report that knock-out mice with Tsc1 gene inactivation in glia (Tsc1(GFAP)CKO mice) exhibit decreased expression of the astrocytic connexin protein, Cx43, and an associated impairment in gap junction coupling between astrocytes. Correspondingly, hippocampal slices from Tsc1(GFAP)CKO mice have increased extracellular potassium concentration in response to stimulation. This impaired potassium buffering can be attributed to abnormal gap junction coupling, as a gap junction inhibitor elicits an additional increase in potassium concentration in control, but not Tsc1(GFAP)CKO slices. Furthermore, treatment with a mammalian target of rapamycin inhibitor reverses the deficient Cx43 expression and impaired potassium buffering. These findings suggest that Tsc1 inactivation in astrocytes causes defects in astrocytic gap junction coupling and potassium clearance, which may contribute to epilepsy in Tsc1(GFAP)CKO mice.

  15. Effect of the electromagnetic environment on current fluctuations in driven tunnel junctions

    Science.gov (United States)

    Frey, Moritz; Grabert, Hermann

    2016-07-01

    We examine current fluctuations in tunnel junctions driven by a superposition of a constant and a sinusoidal voltage source. In standard setups, the external voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. The modes of this environment are excited by the time-dependent voltage and are the source of Johnson-Nyquist noise. We determine the autocorrelation function of the current flowing in the leads of the junction in the weak tunneling limit up to terms of second order in the tunneling Hamiltonian. The driven modes of the electromagnetic environment are treated exactly by means of a unitary transformation introduced recently. Particular emphasis is placed on the spectral function of the current fluctuations. The spectrum is found to comprise three contributions: a term arising from the Johnson-Nyquist noise of the environmental impedance, a part due to the shot noise of the tunneling element, and a third contribution which comes from the cross correlation between fluctuations caused by the electromagnetic environment and fluctuations of the tunneling current. All three parts of the spectral function occur already for devices under dc bias. The spectral function of ac driven tunneling elements can be determined from the result for a dc bias by means of a photoassisted tunneling relation of the Tien-Gordon type. Specific results are given for an Ohmic environment and for a junction driven through a resonator.

  16. Thermodynamically stable RNA three-way junction for constructing multifunctional nanoparticles for delivery of therapeutics

    Science.gov (United States)

    Shu, Dan; Shu, Yi; Haque, Farzin; Abdelmawla, Sherine; Guo, Peixuan

    2011-10-01

    RNA nanoparticles have applications in the treatment of cancers and viral infection; however, the instability of RNA nanoparticles has hindered their development for therapeutic applications. The lack of covalent linkage or crosslinking in nanoparticles causes dissociation in vivo. Here we show that the packaging RNA of bacteriophage phi29 DNA packaging motor can be assembled from 3-6 pieces of RNA oligomers without the use of metal salts. Each RNA oligomer contains a functional module that can be a receptor-binding ligand, aptamer, short interfering RNA or ribozyme. When mixed together, they self-assemble into thermodynamically stable tri-star nanoparticles with a three-way junction core. These nanoparticles are resistant to 8 M urea denaturation, are stable in serum and remain intact at extremely low concentrations. The modules remain functional in vitro and in vivo, suggesting that the three-way junction core can be used as a platform for building a variety of multifunctional nanoparticles. We studied 25 different three-way junction motifs in biological RNA and found only one other motif that shares characteristics similar to the three-way junction of phi29 pRNA.

  17. Junctional neurulation: a unique developmental program shaping a discrete region of the spinal cord highly susceptible to neural tube defects.

    Science.gov (United States)

    Dady, Alwyn; Havis, Emmanuelle; Escriou, Virginie; Catala, Martin; Duband, Jean-Loup

    2014-09-24

    In higher vertebrates, the primordium of the nervous system, the neural tube, is shaped along the rostrocaudal axis through two consecutive, radically different processes referred to as primary and secondary neurulation. Failures in neurulation lead to severe anomalies of the nervous system, called neural tube defects (NTDs), which are among the most common congenital malformations in humans. Mechanisms causing NTDs in humans remain ill-defined. Of particular interest, the thoracolumbar region, which encompasses many NTD cases in the spine, corresponds to the junction between primary and secondary neurulations. Elucidating which developmental processes operate during neurulation in this region is therefore pivotal to unraveling the etiology of NTDs. Here, using the chick embryo as a model, we show that, at the junction, the neural tube is elaborated by a unique developmental program involving concerted movements of elevation and folding combined with local cell ingression and accretion. This process ensures the topological continuity between the primary and secondary neural tubes while supplying all neural progenitors of both the junctional and secondary neural tubes. Because it is distinct from the other neurulation events, we term this phenomenon junctional neurulation. Moreover, the planar-cell-polarity member, Prickle-1, is recruited specifically during junctional neurulation and its misexpression within a limited time period suffices to cause anomalies that phenocopy lower spine NTDs in human. Our study thus provides a molecular and cellular basis for understanding the causality of NTD prevalence in humans and ascribes to Prickle-1 a critical role in lower spinal cord formation.

  18. Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhao [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States); Jin, Zhu-Qiu, E-mail: zhu-qiu.jin@sdstate.edu [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States)

    2012-08-31

    Highlights: Black-Right-Pointing-Pointer Cardiac tight junctions are present between coronary endothelial cells. Black-Right-Pointing-Pointer Ischemic preconditioning preserves the structural and functional integrity of tight junctions. Black-Right-Pointing-Pointer Myocardial edema is prevented in hearts subjected to ischemic preconditioning. Black-Right-Pointing-Pointer Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood-heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs-Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC

  19. Electron Transport through Porphyrin Molecular Junctions

    Science.gov (United States)

    Zhou, Qi

    The goal of this work is to study the properties that would affect the electron transport through a porphyrin molecular junction. This work contributes to the field of electron transport in molecular junctions in the following 3 aspects. First of all, by carrying out experiments comparing the conductance of the iron (III) porphyrin (protected) and the free base porphyrin (protected), it is confirmed that the molecular energy level broadening and shifting occurs for porphyrin molecules when coupled with the metal electrodes, and this level broadening and shifting plays an important role in the electron transport through molecular junctions. Secondly, by carrying out an in-situ deprotection of the acetyl-protected free base porphyrin molecules, it is found out that the presence of acetyl groups reduces the conductance. Thirdly, by incorporating the Matrix-assisted laser desorption/ionization (MALDI) spectrum and the in-situ deprotection prior to formation of molecular junctions, it allows a more precise understanding of the molecules involved in the formation of molecular junctions, and therefore allows an accurate analysis of the conductance histogram. The molecules are prepared by self-assembly and the junctions are formed using a Scanning Tunneling Microscopy (STM) molecular break junction technique. The porphyrin molecules are characterized by MALDI in solution before self-assembly to a gold/mica substrate. The self-assembled monolayers (SAMs) of porphyrins on gold are characterized by Ultraviolet-visible (UV-Vis) reflection spectroscopy to confirm that the molecules are attached to the substrate. The SAMs are then characterized by Angle-Resolved X-ray photoelectron spectroscopy (ARXPS) to determine the thickness and the average molecular orientation of the molecular layer. The electron transport is measured by conductance-displacement (G-S) experiments under a given bias (-0.4V). The conductance value of a single molecule is identified by a statistical analysis

  20. ADAMTS-10 and -6 differentially regulate cell-cell junctions and focal adhesions

    Science.gov (United States)

    Cain, Stuart A.; Mularczyk, Ewa J.; Singh, Mukti; Massam-Wu, Teresa; Kielty, Cay M.

    2016-01-01

    ADAMTS10 and ADAMTS6 are homologous metalloproteinases with ill-defined roles. ADAMTS10 mutations cause Weill-Marchesani syndrome (WMS), implicating it in fibrillin microfibril biology since some fibrillin-1 mutations also cause WMS. However little is known about ADAMTS6 function. ADAMTS10 is resistant to furin cleavage, however we show that ADAMTS6 is effectively processed and active. Using siRNA, over-expression and mutagenesis, it was found ADAMTS6 inhibits and ADAMTS10 is required for focal adhesions, epithelial cell-cell junction formation, and microfibril deposition. Either knockdown of ADAMTS6, or disruption of its furin processing or catalytic sites restores focal adhesions, implicating its enzyme activity acts on targets in the focal adhesion complex. In ADAMTS10-depleted cultures, expression of syndecan-4 rescues focal adhesions and cell-cell junctions. Recombinant C-termini of ADAMTS10 and ADAMTS6, both of which induce focal adhesions, bind heparin and syndecan-4. However, cells overexpressing full-length ADAMTS6 lack heparan sulphate and focal adhesions, whilst depletion of ADAMTS6 induces a prominent glycocalyx. Thus ADAMTS10 and ADAMTS6 oppositely affect heparan sulphate-rich interfaces including focal adhesions. We previously showed that microfibril deposition requires fibronectin-induced focal adhesions, and cell-cell junctions in epithelial cultures. Here we reveal that ADAMTS6 causes a reduction in heparan sulphate-rich interfaces, and its expression is regulated by ADAMTS10. PMID:27779234

  1. Electron optics with p-n junctions in ballistic graphene

    Science.gov (United States)

    Chen, Shaowen; Han, Zheng; Elahi, Mirza M.; Habib, K. M. Masum; Wang, Lei; Wen, Bo; Gao, Yuanda; Taniguchi, Takashi; Watanabe, Kenji; Hone, James; Ghosh, Avik W.; Dean, Cory R.

    2016-09-01

    Electrons transmitted across a ballistic semiconductor junction are expected to undergo refraction, analogous to light rays across an optical boundary. In graphene, the linear dispersion and zero-gap band structure admit highly transparent p-n junctions by simple electrostatic gating. Here, we employ transverse magnetic focusing to probe the propagation of carriers across an electrostatically defined graphene junction. We find agreement with the predicted Snell’s law for electrons, including the observation of both positive and negative refraction. Resonant transmission across the p-n junction provides a direct measurement of the angle-dependent transmission coefficient. Comparing experimental data with simulations reveals the crucial role played by the effective junction width, providing guidance for future device design. Our results pave the way for realizing electron optics based on graphene p-n junctions.

  2. Single P-N junction tandem photovoltaic device

    Science.gov (United States)

    Walukiewicz, Wladyslaw; Ager, III, Joel W.; Yu, Kin Man

    2011-10-18

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  3. The critical power to maintain thermally stable molecular junctions

    Science.gov (United States)

    Wang, Yanlei; Xu, Zhiping

    2014-07-01

    With the rise of atomic-scale devices such as molecular electronics and scanning probe microscopies, energy transport processes through molecular junctions have attracted notable research interest recently. In this work, heat dissipation and transport across diamond/benzene/diamond molecular junctions are explored by performing atomistic simulations. We identify the critical power Pcr to maintain thermal stability of the junction through efficient dissipation of local heat. We also find that the molecule-probe contact features a power-dependent interfacial thermal resistance RK in the order of 109 kW-1. Moreover, both Pcr and RK display explicit dependence on atomic structures of the junction, force and temperature. For instance, Pcr can be elevated in multiple-molecule junctions, and streching the junction enhances RK by a factor of 2. The applications of these findings in molecular electronics and scanning probing measurements are discussed, providing practical guidelines in their rational design.

  4. Single P-N junction tandem photovoltaic device

    Science.gov (United States)

    Walukiewicz, Wladyslaw [Kensington, CA; Ager, III, Joel W.; Yu, Kin Man [Lafayette, CA

    2012-03-06

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  5. Structure, regulation and function of gap junctions in liver

    Science.gov (United States)

    Maes, Michaël; Decrock, Elke; Wang, Nan; Leybaert, Luc; da Silva, Tereza Cristina; Veloso Alves Pereira, Isabel; Jaeschke, Hartmut; Cogliati, Bruno; Vinken, Mathieu

    2016-01-01

    Gap junctions are a specialized group of cell-to-cell junctions that mediate direct intercellular communication between cells. They arise from the interaction of 2 hemichannels of adjacent cells, which in turn are composed of 6 connexin proteins. In liver, gap junctions are predominantly found in hepatocytes and play critical roles in virtually all phases of the hepatic life cycle, including cell growth, differentiation, liver-specific functionality and cell death. Liver gap junctions are directed through a broad variety of mechanisms ranging from epigenetic control of connexin expression to posttranslational regulation of gap junction activity. This paper reviews established and novel aspects regarding the architecture, control and functional relevance of liver gap junctions. PMID:27001459

  6. Gap junction proteins in the light-damaged albino rat.

    Science.gov (United States)

    Guo, Cindy X; Tran, Henry; Green, Colin R; Danesh-Meyer, Helen V; Acosta, Monica L

    2014-01-01

    Changes in connexin expression are associated with many pathological conditions seen in animal models and in humans. We hypothesized that gap junctions are important mediators in tissue dysfunction and injury processes in the retina, and therefore, we investigated the pattern of connexin protein expression in the light-damaged albino rat eye. Adult Sprague-Dawley rats were exposed to intense light for 24 h. The animals were euthanized, and ocular tissue was harvested at 0 h, 6 h, 24 h, 48 h, and 7 days after light damage. The tissues were processed for immunohistochemistry and western blotting to analyze the expression of the gap junction proteins in the light-damaged condition compared to the non-light-damaged condition. Cell death was detected using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) technique. Intense light exposure caused increased TUNEL labeling of photoreceptor cells. Immunocytochemistry revealed that connexin 36 (Cx36) was significantly increased in the inner plexiform layer and Cx45 was significantly decreased in the light-damaged retina. The pattern of Cx36 and Cx45 labeling returned to normal 7 days after light damage. Cx43 significantly increased in the RPE and the choroid in the light-damaged tissue, and decreased but not significantly in the retina. This elevated Cx43 expression in the choroid colocalized with markers of nitration-related oxidative stress (nitrotyrosine) and inflammation (CD45 and ionized calcium-binding adaptor molecule-1) in the choroid. The results suggest that connexins are regulated differently in the retina than in the choroid in response to photoreceptor damage. Changes in connexins, including Cx36, Cx43, and Cx45, may contribute to the damage process. Specifically, Cx43 was associated with inflammatory damage. Therefore, connexins may be candidate targets for treatment for ameliorating disease progression.

  7. Geometrical theory of triple junctions of CSL boundaries.

    Science.gov (United States)

    Gertsman, V Y

    2001-07-01

    When three grain boundaries having misorientations generating coincidence site lattices (CSLs) meet at a triple junction, a common (triple-junction) CSL is formed. A theory is developed as a set of theorems establishing the relationships between the geometrical parameters of the grain-boundary and triple-junction CSLs. Application of the theory is demonstrated in detail for the case of the cubic crystal system. It is also shown how the theory can be extended to an arbitrary crystal lattice.

  8. Turbulence-induced magnetic flux asymmetry at nanoscale junctions

    OpenAIRE

    2007-01-01

    It was recently predicted [J. Phys.: Condens. Matter 18, 11059 (2006)] that turbulence of the electron flow may develop at nonadiabatic nanoscale junctions under appropriate conditions. Here we show that such an effect leads to an asymmetric current-induced magnetic field on the two sides of an otherwise symmetric junction. We propose that by measuring the fluxes ensuing from these fields across two surfaces placed at the two sides of the junction would provide direct and noninvasive evidence...

  9. Magnetic interaction between spatially extended superconducting tunnel junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    2002-01-01

    A general description of magnetic interactions between superconducting tunnel junctions is given. The description covers a wide range of possible experimental systems, and we explicitly explore two experimentally relevant limits of coupled junctions. One is the limit of junctions with tunneling...... been considered through arrays of superconducting weak links based on semiconductor quantum wells with superconducting electrodes. We use the model to make direct interpretations of the published experiments and thereby propose that long-range magnetic interactions are responsible for the reported...

  10. Endoplasmic reticulum-plasma membrane junctions: structure, function and dynamics.

    Science.gov (United States)

    Okeke, Emmanuel; Dingsdale, Hayley; Parker, Tony; Voronina, Svetlana; Tepikin, Alexei V

    2016-06-01

    Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are contact sites between the ER and the PM; the distance between the two organelles in the junctions is below 40 nm and the membranes are connected by protein tethers. A number of molecular tools and technical approaches have been recently developed to visualise, modify and characterise properties of ER-PM junctions. The junctions serve as the platforms for lipid exchange between the organelles and for cell signalling, notably Ca(2+) and cAMP signalling. Vice versa, signalling events regulate the development and properties of the junctions. Two Ca(2+) -dependent mechanisms of de novo formation of ER-PM junctions have been recently described and characterised. The junction-forming proteins and lipids are currently the focus of vigorous investigation. Junctions can be relatively short-lived and simple structures, forming and dissolving on the time scale of a few minutes. However, complex, sophisticated and multifunctional ER-PM junctions, capable of attracting numerous protein residents and other cellular organelles, have been described in some cell types. The road from simplicity to complexity, i.e. the transformation from simple 'nascent' ER-PM junctions to advanced stable multiorganellar complexes, is likely to become an attractive research avenue for current and future junctologists. Another area of considerable research interest is the downstream cellular processes that can be activated by specific local signalling events in the ER-PM junctions. Studies of the cell physiology and indeed pathophysiology of ER-PM junctions have already produced some surprising discoveries, likely to expand with advances in our understanding of these remarkable organellar contact sites. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  11. Engineering of Droplet Manipulation in Tertiary Junction Microfluidic Channels

    Science.gov (United States)

    2017-06-30

    in silico investigation of path selection by a single droplet inside a tertiary junction microchannel using oil-in-water as a model system. The...droplet was generated at a T-junction inside a microfluidic chip and its flow behaviour as a function of droplet size, streamline position, viscosity...investigation of path selection by a single droplet inside a tertiary- junction microchannel using oil-in-water as a model system. The droplet was generated at

  12. ACCIDENT PREDICTION MODELS FOR UNSIGNALISED URBAN JUNCTIONS IN GHANA

    OpenAIRE

    Mohammed SALIFU, MSc., PhD, MIHT, MGhIE

    2004-01-01

    The main objective of this study was to provide an improved method for safety appraisal in Ghana through the development and application of suitable accident prediction models for unsignalised urban junctions. A case study was designed comprising 91 junctions selected from the two most cosmopolitan cities in Ghana. A wide range of traffic and road data together with the corresponding accident data for each junction for the three-year period 1996-1998 was utilized in the model development p...

  13. Localized and generalized forms of blistering in junctional epidermolysis bullosa due to COL17A1 mutations in the Netherlands

    NARCIS (Netherlands)

    Pasmooij, A. M. G.; Pas, H. H.; Jansen, G. H. L.; Lemmink, H. H.; Jonkman, M. F.

    2007-01-01

    Background Mutations in the gene COL17A1 coding for type XVII collagen cause non-Herlitz junctional epidermolysis bullosa (nH-JEB). Objectives Here we give an overview of the genotype-phenotype correlation in 12 patients from the Netherlands with type XVII collagen-deficient nH-JEB. Patient and meth

  14. Oral bacterial adhesion forces to biomaterial surfaces constituting the bracket-adhesive-enamel junction in orthodontic treatment

    NARCIS (Netherlands)

    Mei, Li; Busscher, Henk J; van der Mei, Henny C; Chen, Yangxi; de Vries, Joop; Ren, Yijin

    2009-01-01

    Bacterial adhesion to biomaterial surfaces constituting the bracket-adhesive-enamel junction represents a growing problem in orthodontics, because bacteria can adversely affect treatment by causing demineralization of the enamel surface around the brackets. It is important to know the forces with wh

  15. Oral bacterial adhesion forces to biomaterial surfaces constituting the bracket-adhesive-enamel junction in orthodontic treatment

    NARCIS (Netherlands)

    Mei, Li; Busscher, Henk J; van der Mei, Henny C; Chen, Yangxi; de Vries, Joop; Ren, Yijin

    Bacterial adhesion to biomaterial surfaces constituting the bracket-adhesive-enamel junction represents a growing problem in orthodontics, because bacteria can adversely affect treatment by causing demineralization of the enamel surface around the brackets. It is important to know the forces with

  16. Localized and generalized forms of blistering in junctional epidermolysis bullosa due to COL17A1 mutations in the Netherlands

    NARCIS (Netherlands)

    Pasmooij, A. M. G.; Pas, H. H.; Jansen, G. H. L.; Lemmink, H. H.; Jonkman, M. F.

    Background Mutations in the gene COL17A1 coding for type XVII collagen cause non-Herlitz junctional epidermolysis bullosa (nH-JEB). Objectives Here we give an overview of the genotype-phenotype correlation in 12 patients from the Netherlands with type XVII collagen-deficient nH-JEB. Patient and

  17. Some chaotic features of intrinsically coupled Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Kolahchi, M.R., E-mail: kolahchi@iasbs.ac.ir [Institute for Advanced Studies in Basic Sciences, Zanjan 45195-1159 (Iran, Islamic Republic of); Shukrinov, Yu.M. [BLTP, JINR, Dubna, Moscow Region 141980 (Russian Federation); Max-Planck-Institute for the Physics of Complex Systems, 01187 Dresden (Germany); Hamdipour, M. [Institute for Advanced Studies in Basic Sciences, Zanjan 45195-1159 (Iran, Islamic Republic of); BLTP, JINR, Dubna, Moscow Region 141980 (Russian Federation); Botha, A.E. [Department of Physics, University of South Africa, P.O. Box 392, Pretoria 0003 (South Africa); Suzuki, M. [Photonics and Electronics Science and Engineering Center and Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan)

    2013-08-15

    Highlights: ► Intrinsically coupled Josephson junctions model a high-T{sub c} superconductor. ► Intrinsically coupled Josephson junctions can act as a chaotic nonlinear system. ► Chaos could be due to resonance overlap. ► Avoiding parameters that lead to chaos is important for the design of resonators. -- Abstract: We look for chaos in an intrinsically coupled system of Josephson junctions. This study has direct applications for the high-T{sub c} resonators which require coherence amongst the junctions.

  18. Imaging snake orbits at graphene n -p junctions

    Science.gov (United States)

    Kolasiński, K.; Mreńca-Kolasińska, A.; Szafran, B.

    2017-01-01

    We consider conductance mapping of the snake orbits confined along the n -p junction defined in graphene by the electrostatic doping in the quantum Hall regime. We explain the periodicity of conductance oscillations at the magnetic field and the Fermi energy scales by the properties of the n -p junction as a conducting channel. We evaluate the conductance maps for a floating gate scanning the surface of the device. In the quantum Hall conditions the currents flow near the edges of the sample and along the n -p junction. The conductance mapping resolves only the n -p junction and not the edges. The conductance oscillations along the junction are found in the maps with periodicity related to the cyclotron orbits of the scattering current. Stronger probe potentials provide support to localized resonances at one of the sides of the junction with current loops that interfere with the n -p junction currents. The interference results in a series of narrow lines parallel to the junction with positions that strongly depend on the magnetic field through the Aharonov-Bohm effect. The consequences of a limited transparency of finite-width n -p junctions are also discussed.

  19. Assemble four-arm DNA junctions into nanoweb

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    DNA is of structural polymorphism, which is useful in nanoarchitecture; especially, four-arm DNA junc tions can be used to assemble nanowebs. The static four-arm DNA junctions were designed and synthesized. One-arm DNA and two-arm DNA came out simultaneously with the four-arm DNA junction's formation. A new method, termed the two-step method, was proposed and the productivity of four-arm DNA junctions was increased. A nanoweb was assembled successfully, but it showed irregularity itself. It was not the same as we expected. We consider that it is aresult from the flexibility of four-arm DNA junction.

  20. Terahertz Detection with Twin Superconductor-Insulator-Superconductor Tunnel Junctions

    Institute of Scientific and Technical Information of China (English)

    LI Jing; WANG Ming-Jye; SHI Sheng-Cai; Hiroshi Mat-suo

    2007-01-01

    Terahertz detection with twin superconductor-insulator-superconductor (SIS) tunnel junctions, which are connected in parallel via an inductive thin-film superconducting microstrip line, is mainly studied. Firstly, we investigate the direct-detection response of a superconducting twin-junction device by means of a Fourier transform spectrometer. Secondly, we construct a direct-detection model of twin SIS tunnel junctions. The superconducting twin-junction device is then simulated in terms of the constructed model. The simulation result is found to be in good agreement with the measured one. In addition, we observe that the direct-detection response of the device is consistent with the noise temperature behaviour.

  1. F-Theory Description of 3-String Junction

    Institute of Scientific and Technical Information of China (English)

    YANGFu-Zhong

    2003-01-01

    The geometrical description of BPS 3-string junction in the F-theory background is given by lifting a string junction in lib into F-theory and constructing a holomorphic curve in K3 with respect to a special complex structure of K3. The holomorphic curve is fibration of 1-cycles of the elliptic fiber over the geodesic string junction. The F-theory picture in this paper provides a unifying description of both string and string junction, and is advantageous over their M-theory picture.

  2. F-Theory Description of 3-String Junction

    Institute of Scientific and Technical Information of China (English)

    YANG Fu-Zhong

    2003-01-01

    The geometrical description of BPS 3-string junction in the F-theory background is given by lifting a string junction in IIB into F-theory and constructing a holomorphic curve in K3 with respect to a special complex structure of K3. The holomorphic curve is fibration of 1-cycles of the elliptic fiber over the geodesic string junction. The F-theory picture in this paper provides a unifying description of both string and string junction, and is advantageous over their M-theory picture.

  3. ‘Gap Junctions and Cancer: Communicating for 50 Years’

    Science.gov (United States)

    Aasen, Trond; Mesnil, Marc; Naus, Christian C.; Lampe, Paul D.; Laird, Dale W.

    2017-01-01

    Fifty years ago, tumour cells were found to lack electrical coupling, leading to the hypothesis that loss of direct intercellular communication is commonly associated with cancer onset and progression. Subsequent studies linked this phenomenon to gap junctions composed of connexin proteins. While many studies support the notion that connexins are tumour suppressors, recent evidence suggests that, in some tumour types, they may facilitate specific stages of tumour progression through both junctional and non-junctional signalling pathways. This Timeline article highlights the milestones connecting gap junctions to cancer, and underscores important unanswered questions, controversies and therapeutic opportunities in the field. PMID:27782134

  4. Superconducting Tunnel Junction Arrays for UV Photon Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative method is described for the fabrication of superconducting tunnel junction (STJ) detector arrays offering true "three dimensional" imaging throughout...

  5. Improving transition voltage spectroscopy of molecular junctions

    DEFF Research Database (Denmark)

    Markussen, Troels; Chen, Jingzhe; Thygesen, Kristian Sommer

    2011-01-01

    Transition voltage spectroscopy (TVS) is a promising spectroscopic tool for molecular junctions. The principles in TVS is to find the minimum on a Fowler-Nordheim plot where ln(I/V2) is plotted against 1/V and relate the voltage at the minimum Vmin to the closest molecular level. Importantly, Vmin...... is approximately half the voltage required to see a peak in the dI/dV curve. Information about the molecular level position can thus be obtained at relatively low voltages. In this work we show that the molecular level position can be determined at even lower voltages, Vmin(α), by finding the minimum of ln...

  6. Anatomy and biomechanics of the craniovertebral junction.

    Science.gov (United States)

    Lopez, Alejandro J; Scheer, Justin K; Leibl, Kayla E; Smith, Zachary A; Dlouhy, Brian J; Dahdaleh, Nader S

    2015-04-01

    The craniovertebral junction (CVJ) has unique anatomical structures that separate it from the subaxial cervical spine. In addition to housing vital neural and vascular structures, the majority of cranial flexion, extension, and axial rotation is accomplished at the CVJ. A complex combination of osseous and ligamentous supports allow for stability despite a large degree of motion. An understanding of anatomy and biomechanics is essential to effectively evaluate and address the various pathological processes that may affect this region. Therefore, the authors present an up-to-date narrative review of CVJ anatomy, normal and pathological biomechanics, and fixation techniques.

  7. Magnetic resonance imaging in craniovertebral junction anomaly

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Shimpei; Hata, Yuichi; Miyamoto, Yukio

    1985-03-01

    Materials consisted of 6 cases with occipitalization of the atlas, (4 of them complicated by basilar impression), 7 with basilar impression, one with hypoplasia of the atlas and C2-3 fusion, and one with os odontoideum. Basal angles after Welcker were all more than 130 in contrast to 118-138 (127 an average) in control group. Basal angle more than 140 denoted platybasia. Syringomyelia was seen in 7 of all 15 cases and 4 of 5 cases with platybasia. Chiari malformation was seen in 9 of all 15 cases and 4 of 5 with platybasia. Basal angles were closely related to craniovertebral junction bone anomaly, syringomyelia, and Chiari malformation. (author).

  8. Magic-T Junction using Microstrip/Slotline Transitions

    Science.gov (United States)

    U-yen, Kongpop; Wollack, Edward J.; Doiron, Terence

    2008-01-01

    An improved broadband planar magic-T junction that incorporates microstrip/slotline transitions has been developed. In comparison with a prior broadband magic-T junction incorporating microstrip/slotline transitions, this junction offers superior broadband performance. In addition, because this junction is geometrically simpler and its performance is less affected by fabrication tolerances, the benefits of the improved design can be realized at lower fabrication cost. There are potential uses for junctions like this one in commercial microwave communication receivers, radar and polarimeter systems, and industrial microwave instrumentation. A magic-T junction is a four-port waveguide junction consisting of a combination of an H-type and an E-type junction. An E-type junction is so named because it includes a junction arm that extends from a main waveguide in the same direction as that of the electric (E) field in the waveguide. An H-type junction is so named because it includes a junction arm parallel to the magnetic (H) field in a main waveguide. A magic-T junction includes two input ports (here labeled 1 and 2, respectively) and two output ports (here labeled E and H, respectively). In an ideal case, (1) a magic-T junction is lossless, (2) the input signals add (that is, they combine in phase with each other) at port H, and (3) the input signals subtract (that is, they combine in opposite phase) at port E. The prior junction over which the present junction is an improvement affords in-phase-combining characterized by a broadband frequency response, and features a small slotline area to minimize in-band loss. However, with respect to isolation between ports 1 and 2 and return loss at port E, it exhibits narrowband frequency responses. In addition, its performance is sensitive to misalignment of microstrip and slotline components: this sensitivity is attributable to a limited number of quarter-wavelength (lambda/4) transmission-line sections for matching impedances

  9. Grades 1-8, Apache Junction Unified School District 43, Apache Junction, Arizona. PLATO Evaluation Series.

    Science.gov (United States)

    Quinn, David W.; Quinn, Nancy W.

    Apache Junction Unified School District, Arizona, has embarked on a 5-year program of instructional improvement using technology. PLATO Elementary reading and mathematics products were installed in the district's elementary and middle schools at the beginning of the 1999-2000 school year. This evaluation studied the use and preliminary student…

  10. Fabrication of magnetic tunnel junctions with epitaxial and textured ferromagnetic layers

    Science.gov (United States)

    Chang, Y. Austin; Yang, Jianhua Joshua

    2008-11-11

    This invention relates to magnetic tunnel junctions and methods for making the magnetic tunnel junctions. The magnetic tunnel junctions include a tunnel barrier oxide layer sandwiched between two ferromagnetic layers both of which are epitaxial or textured with respect to the underlying substrate upon which the magnetic tunnel junctions are grown. The magnetic tunnel junctions provide improved magnetic properties, sharper interfaces and few defects.

  11. Potassium ion recycling pathway via gap junction systems in the mammalian cochlea and its interruption in hereditary nonsyndromic deafness.

    Science.gov (United States)

    Kikuchi, T; Adams, J C; Miyabe, Y; So, E; Kobayashi, T

    2000-01-01

    In the mammalian cochlea, there are two independent gap junction systems, the epithelial cell gap junction system and the connective tissue cell gap junction system. Thus far, four different connexin molecules, including connexin 26, 30, 31, and 43, have been reported in the cochlea. The two networks of gap junctions form the route by which K+ ions that pass through the sensory cells during mechanosensory transduction can be recycled back to the endolymphatic space, from which they reenter the sensory cells. Activation of hair cells by acoustic stimuli induces influx of K+ ions from the endolymph to sensory hair cells. These K+ ions are released basolaterally to the extracellular space of the organ of Corti, from which they enter the cochlear supporting cells. Once inside the supporting cells they move via the epithelial cell gap junction system laterally to the lower part of the spiral ligament. The K+ ions are released into the extracellular space of the spiral ligament by root cells and taken up by type II fibrocytes. This uptake incorporates K+ into the connective tissue gap junction system. Within this system, the K+ ions pass through the tight junctional barrier of the stria vascularis and are released within the intrastrial extracellular space. The marginal cells of the stria vascularis then take up K+ and return it to the endolymphatic space, where it can be used again in sensory transduction. It is highly probable that mutations of connexin genes that result in human nonsyndromic deafness cause dysfunction of cochlear gap junctions and thereby interrupt K+ ion recirculation pathways. In addition to connexin mutations, other conditions may disrupt gap junctions within the ear. For example, mice with a functionally significant mutation of Brain-4, which is expressed in the connective tissue cells within the cochlea, show marked depression of the endolymphatic potential and profound sensorineural hearing loss. It seems likely that disruption of connective

  12. Antenna-Coupled Superconducting Tunnel Junctions with Single-Electron Transistor Readout for Detection of Sub-mm Radiation

    Science.gov (United States)

    Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Wollack, E. J.; Schoelkopf, R. J.; Teufel, J.; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    Antenna-coupled superconducting tunnel junction detectors have the potential for photon-counting sensitivity at sub-mm wavelengths. The device consists of an antenna structure to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure currents through tunnel junction contacts to the absorber volume. We will describe optimization of device parameters, and recent results on fabrication techniques for producing devices with high yield for detector arrays. We will also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

  13. Gap junctions in the nervous system.

    Science.gov (United States)

    Rozental, R; Giaume, C; Spray, D C

    2000-04-01

    Synapses are classically defined as close connections between two nerve cells or between a neuronal cell and a muscle or gland cell across which a chemical signal (i.e., a neurotransmitter) and/or an electrical signal (i.e., current-carrying ions) can pass. The definition of synapse was developed by Charles Sherrington and by Ramon y Cajal at the beginning of this century and refined by John Eccles and Bernard Katz 50 years later; in this collection of papers, the definition of synapses is discussed further in the chapter by Mike Bennett. who provided the first functional demonstration of electrical transmission via gap junction channels between vertebrate neurons. As is evidenced by the range of topics covered in this issue, research dealing with gap junctions in the nervous system has expanded enormously in the past decade, major findings being that specific cell types in the brain expresses specific types of connexins and that expression patterns coincide with tissue compartmentalization and function and that these compartments change during development.

  14. Electrophysiological study in neuromuscular junction disorders

    Directory of Open Access Journals (Sweden)

    Ajith Cherian

    2013-01-01

    Full Text Available This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS, congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS. SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation.

  15. Improving transition voltage spectroscopy of molecular junctions

    Science.gov (United States)

    Markussen, Troels; Chen, Jingzhe; Thygesen, Kristian S.

    2011-04-01

    Transition voltage spectroscopy (TVS) is a promising spectroscopic tool for molecular junctions. The principles in TVS is to find the minimum on a Fowler-Nordheim plot where ln(I/V2) is plotted against 1/V and relate the voltage at the minimum Vmin to the closest molecular level. Importantly, Vmin is approximately half the voltage required to see a peak in the dI/dV curve. Information about the molecular level position can thus be obtained at relatively low voltages. In this work we show that the molecular level position can be determined at even lower voltages, Vmin(α), by finding the minimum of ln(I/Vα) with α<2. On the basis of a simple Lorentzian transmission model we analyze theoretical ab initio as well as experimental I-V curves and show that the voltage required to determine the molecular levels can be reduced by ~30% as compared to conventional TVS. As for conventional TVS, the symmetry/asymmetry of the molecular junction needs to be taken into account in order to gain quantitative information. We show that the degree of asymmetry may be estimated from a plot of Vmin(α) vs α.

  16. Development of superconducting tunnel junction radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Katagiri, Masaki; Kishimoto, Maki; Ukibe, Masahiro; Nakamura, Tatsuya; Nakazawa, Masaharu [Japan Atomic Energy Research Inst., Tokyo (Japan); Kurakado, Masahiko; Ishibashi, Kenji; Maehata, Keisuke

    1998-07-01

    Study on development of high energy resolution X-ray detector using superconducting tunnel junction (STJ) for radiation detection was conducted for 5 years under cooperation of University of Tokyo group and Kyushu University group by Quantum measurement research group of Advanced fundamental research center of JAERI. As the energy resolution of STJ could be obtained better results than that of Si semiconductor detector told to be actually best at present, this study aimed to actualize an X-ray detector usable for the experimental field and to elucidate radiation detection mechanism due to STJ. The STJ element used for this study was the one developed by Kurakado group of Nippon Steel Corp. As a results, some technical problems were almost resolved, which made some trouble when using the STJ element to detection element of X-ray spectrometer. In order to make the X-ray detector better, it is essential to manufacture a STJ element and develop serial junction type STJ element on the base of optimization of the element structure and selection and single crystallization of new superconducting materials such as Ta and others, activating the research results. (G.K.)

  17. Junction like behavior in polycrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran, Shivakumar, E-mail: sbhaskar@mail.uh.edu [Department of Electrical and Computer Engineering, Cullen College of Engineering, University of Houston, TX 77004 (United States); Charlson, Earl Joe; Litvinov, Dmitri [Department of Electrical and Computer Engineering, Cullen College of Engineering, University of Houston, TX 77004 (United States); Makarenko, Boris [Department of Chemistry, University of Houston, TX 77004 (United States)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer The result that we obtained are compared with single crystalline diamond devices. Black-Right-Pointing-Pointer The barrier height of 4.4 eV matches the ideal pn-junction barrier height of diamond thin film. - Abstract: We have successfully fabricated polycrystalline diamond rectifying junction devices on n-type (1 0 0) silicon substrates by Hot Filament Chemical Vapor Deposition (HFCVD) using methane/hydrogen process gas and trimethyl borate and trimethyl phosphite dissolved in acetone as p- and n-type dopants, respectively. Impedance spectroscopy and current-voltage analysis indicates that the conduction is vertical down the grains and facets and not due to surface effects. Electrical characteristics were analyzed with In and Ti/Au top metal contacts with Al as the substrate contact. Current-voltage characteristics as a function of temperature showed barrier potentials of 1.1 eV and 0.77 eV for the In and Ti/Au contacts, respectively. Barrier heights of 4.8 eV (In) and 4.4 eV (Ti/Au) were obtained from capacitance-voltage measurements.

  18. GAP junctional communication in brain secondary organizers.

    Science.gov (United States)

    Bosone, Camilla; Andreu, Abraham; Echevarria, Diego

    2016-06-01

    Gap junctions (GJs) are integral membrane proteins that enable the direct cytoplasmic exchange of ions and low molecular weight metabolites between adjacent cells. They are formed by the apposition of two connexons belonging to adjacent cells. Each connexon is formed by six proteins, named connexins (Cxs). Current evidence suggests that gap junctions play an important part in ensuring normal embryo development. Mutations in connexin genes have been linked to a variety of human diseases, although the precise role and the cell biological mechanisms of their action remain almost unknown. Among the big family of Cxs, several are expressed in nervous tissue but just a few are expressed in the anterior neural tube of vertebrates. Many efforts have been made to elucidate the molecular bases of Cxs cell biology and how they influence the morphogenetic signal activity produced by brain signaling centers. These centers, orchestrated by transcription factors and morphogenes determine the axial patterning of the mammalian brain during its specification and regionalization. The present review revisits the findings of GJ composed by Cx43 and Cx36 in neural tube patterning and discuss Cx43 putative enrollment in the control of Fgf8 signal activity coming from the well known secondary organizer, the isthmic organizer. © 2016 The Authors. Development, Growth & Differentiation published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Developmental Biologists.

  19. Annealing free magnetic tunnel junction sensors

    Science.gov (United States)

    Knudde, S.; Leitao, D. C.; Cardoso, S.; Freitas, P. P.

    2017-04-01

    Annealing is a major step in the fabrication of magnetic tunnel junctions (MTJs). It sets the exchange bias between the pinned and antiferromagnetic layers, and helps to increase the tunnel magnetoresistance (TMR) in both amorphous and crystalline junctions. Recent research on MTJs has focused on MgO-based structures due to their high TMR. However, the strict process control and mandatory annealing step can limit the scope of the application of these structures as sensors. In this paper, we present AlOx-based MTJs that are produced by ion beam sputtering and remote plasma oxidation and show optimum transport properties with no annealing. The microfabricated devices show TMR values of up to 35% and using NiFe/CoFeB free layers provides tunable linear ranges, leading to coercivity-free linear responses with sensitivities of up to 5.5%/mT. The top-pinned synthetic antiferromagnetic reference shows a stability of about 30 mT in the microfabricated devices. Sensors with linear ranges of up to 60 mT are demonstrated. This paves the way for the integration of MTJ sensors in heat-sensitive applications such as flexible substrates, or for the design of low-footprint on-chip multiaxial sensing devices.

  20. Switching and Rectification in Carbon-Nanotube Junctions

    Science.gov (United States)

    Srivastava, Deepak; Andriotis, Antonis N.; Menon, Madhu; Chernozatonskii, Leonid

    2003-01-01

    Multi-terminal carbon-nanotube junctions are under investigation as candidate components of nanoscale electronic devices and circuits. Three-terminal "Y" junctions of carbon nanotubes (see Figure 1) have proven to be especially interesting because (1) it is now possible to synthesize them in high yield in a controlled manner and (2) results of preliminary experimental and theoretical studies suggest that such junctions could exhibit switching and rectification properties. Following the preliminary studies, current-versus-voltage characteristics of a number of different "Y" junctions of single-wall carbon nanotubes connected to metal wires were computed. Both semiconducting and metallic nanotubes of various chiralities were considered. Most of the junctions considered were symmetric. These computations involved modeling of the quantum electrical conductivity of the carbon nanotubes and junctions, taking account of such complicating factors as the topological defects (pentagons, heptagons, and octagons) present in the hexagonal molecular structures at the junctions, and the effects of the nanotube/wire interfaces. A major component of the computational approach was the use of an efficient Green s function embedding scheme. The results of these computations showed that symmetric junctions could be expected to support both rectification and switching. The results also showed that rectification and switching properties of a junction could be expected to depend strongly on its symmetry and, to a lesser degree, on the chirality of the nanotubes. In particular, it was found that a zigzag nanotube branching at a symmetric "Y" junction could exhibit either perfect rectification or partial rectification (asymmetric current-versus-voltage characteristic, as in the example of Figure 2). It was also found that an asymmetric "Y" junction would not exhibit rectification.

  1. Stathmin is required for stability of the Drosophila neuromuscular junction.

    Science.gov (United States)

    Graf, Ethan R; Heerssen, Heather M; Wright, Christina M; Davis, Graeme W; DiAntonio, Aaron

    2011-10-19

    Synaptic connections can be stably maintained for prolonged periods, yet can be rapidly disassembled during the developmental refinement of neural circuitry and following cytological insults that lead to neurodegeneration. To date, the molecular mechanisms that determine whether a synapse will persist versus being remodeled or eliminated remain poorly understood. Mutations in Drosophila stathmin were isolated in two independent genetic screens that sought mutations leading to impaired synapse stability at the Drosophila neuromuscular junction (NMJ). Here we demonstrate that Stathmin, a protein that associates with microtubules and can function as a point of signaling integration, is necessary to maintain the stability of the Drosophila NMJ. We show that Stathmin protein is widely distributed within motoneurons and that loss of Stathmin causes impaired NMJ growth and stability. In addition, we show that stathmin mutants display evidence of defective axonal transport, a common feature associated with neuronal degeneration and altered synapse stability. The disassembly of the NMJ in stathmin includes a predictable sequence of cytological events, suggesting that a common program of synapse disassembly is induced following the loss of Stathmin protein. These data define a required function for Stathmin during synapse maintenance in a model system in which there is only a single stathmin gene, enabling future genetic investigation of Stathmin function with potential relevance to the cause and progression of neuromuscular degenerative disease.

  2. Electrical-stress-induced transport and surface potential characterizations of metal/ TiO 2/metal planar junctions

    Science.gov (United States)

    Kim, Haeri; Kim, Dong-Wook

    2011-03-01

    Electric-field-induced resistive switching (RS) phenomena in metal oxides have attracted considerable research interest due to their potential use in nonvolatile memory device applications. Intensive investigations have revealed that coupled electron ion dynamics play a key role the RS mechanism. Metal/single crystal junction can be an ideal model system to study how the ionic drift and diffusion can affect the resistance. We investigated transport and local electrical properties of Pt/ Ti O2 single crystal/Ti planar junctions with micron- sized gaps between the electrodes. Scanning Kelvin probe microscopy (SKPM) showed that negative (positive) electrical stress to the Pt electrodes significantly reduced (hardly affected) the Pt/ Ti O2 contact resistance. The SKPM results also revealed that the electrical stress caused alteration of the local work function of Ti O2 . The comparative investigations of the transport and SKPM results suggested that the electrical stress induced redistribution of ions, resulting in the change of the junction resistance.

  3. Electron transport in graphene/graphene side-contact junction by plane-wave multiple scattering method

    CERN Document Server

    Li, Xiang-Guo; Zhang, X -G; Cheng, Hai-Ping

    2015-01-01

    Electron transport in graphene is along the sheet but junction devices are often made by stacking different sheets together in a "side-contact" geometry which causes the current to flow perpendicular to the sheets within the device. Such geometry presents a challenge to first-principles transport methods. We solve this problem by implementing a plane-wave based multiple scattering theory for electron transport. This implementation improves the computational efficiency over the existing plane-wave transport code, scales better for parallelization over large number of nodes, and does not require the current direction to be along a lattice axis. As a first application, we calculate the tunneling current through a side-contact graphene junction formed by two separate graphene sheets with the edges overlapping each other. We find that transport properties of this junction depend strongly on the AA or AB stacking within the overlapping region as well as the vacuum gap between two graphene sheets. Such transport beh...

  4. Spatiotemporal chaos in capacitively coupled intrinsic Josephson junction arrays and control by a shunted LCR series resonance circuit

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, T G; Yan, S L; Fang, L; He, M; Zhao, X J [Department of Electronics, Nankai University, Tianjin 300071 (China)], E-mail: zhoutg@nankai.edu.cn

    2009-05-15

    The dynamics of capacitively coupled intrinsic Josephson junction arrays with a McCumber parameter {beta}{sub c}<1 driven by a dc current are investigated by using numerical simulations. For the first time, spatiotemporal chaotic behaviors are found. Analysis of the dynamics of individual junctions shows that the chaos is caused by the strong diffusive coupling between the junctions in the array. The chaotic regions of different parameters are also presented, from which the conditions for chaos are deduced. The properties of the array shunted by an LCR series resonance circuit are also investigated. The results show that the spatiotemporal chaos can be effectively controlled by the shunted LCR circuit. This presents a new spatiotemporal chaos control method.

  5. Critical role of gap junction coupled KATP channel activity for regulated insulin secretion.

    Directory of Open Access Journals (Sweden)

    Jonathan V Rocheleau

    2006-02-01

    Full Text Available Pancreatic beta-cells secrete insulin in response to closure of ATP-sensitive K+ (KATP channels, which causes membrane depolarization and a concomitant rise in intracellular Ca2+ (Cai. In intact islets, beta-cells are coupled by gap junctions, which are proposed to synchronize electrical activity and Cai oscillations after exposure to stimulatory glucose (>7 mM. To determine the significance of this coupling in regulating insulin secretion, we examined islets and beta-cells from transgenic mice that express zero functional KATP channels in approximately 70% of their beta-cells, but normal KATP channel density in the remainder. We found that KATP channel activity from approximately 30% of the beta-cells is sufficient to maintain strong glucose dependence of metabolism, Cai, membrane potential, and insulin secretion from intact islets, but that glucose dependence is lost in isolated transgenic cells. Further, inhibition of gap junctions caused loss of glucose sensitivity specifically in transgenic islets. These data demonstrate a critical role of gap junctional coupling of KATP channel activity in control of membrane potential across the islet. Control via coupling lessens the effects of cell-cell variation and provides resistance to defects in excitability that would otherwise lead to a profound diabetic state, such as occurs in persistent neonatal diabetes mellitus.

  6. Critical role of gap junction coupled KATP channel activity for regulated insulin secretion.

    Science.gov (United States)

    Rocheleau, Jonathan V; Remedi, Maria S; Granada, Butch; Head, W Steven; Koster, Joseph C; Nichols, Colin G; Piston, David W

    2006-02-01

    Pancreatic beta-cells secrete insulin in response to closure of ATP-sensitive K+ (KATP) channels, which causes membrane depolarization and a concomitant rise in intracellular Ca2+ (Cai). In intact islets, beta-cells are coupled by gap junctions, which are proposed to synchronize electrical activity and Cai oscillations after exposure to stimulatory glucose (>7 mM). To determine the significance of this coupling in regulating insulin secretion, we examined islets and beta-cells from transgenic mice that express zero functional KATP channels in approximately 70% of their beta-cells, but normal KATP channel density in the remainder. We found that KATP channel activity from approximately 30% of the beta-cells is sufficient to maintain strong glucose dependence of metabolism, Cai, membrane potential, and insulin secretion from intact islets, but that glucose dependence is lost in isolated transgenic cells. Further, inhibition of gap junctions caused loss of glucose sensitivity specifically in transgenic islets. These data demonstrate a critical role of gap junctional coupling of KATP channel activity in control of membrane potential across the islet. Control via coupling lessens the effects of cell-cell variation and provides resistance to defects in excitability that would otherwise lead to a profound diabetic state, such as occurs in persistent neonatal diabetes mellitus.

  7. Treatment with the gap junction modifier rotigaptide (ZP123) reduces infarct size in rats with chronic myocardial infarction.

    Science.gov (United States)

    Haugan, Ketil; Marcussen, Niels; Kjølbye, Anne Louise; Nielsen, Morten Schak; Hennan, James K; Petersen, Jørgen Søberg

    2006-02-01

    Treatment with non-selective drugs (eg, long-chain alcohols, halothane) that reduce gap junction intercellular communication (GJIC) is associated with reduced infarct size after myocardial infarction (MI). Therefore, it has been suggested that gap junction intercellular communication stimulating compounds may increase infarct size. The antiarrhythmic peptide analogue rotigaptide (ZP123) increases cardiac gap junction intercellular communication and the purpose of the present study was to examine the effects of rotigaptide treatment on infarct size. Myocardial infarction was induced in male rats by ligation of the left anterior descending artery (LAD). Rats (n = 156) were treated with rotigaptide at three dose levels or vehicle from the onset of ischemia and for 3 weeks following LAD occlusion. Infarct size was determined using histomorphometry after 3 weeks treatment. Rotigaptide treatment producing steady state plasma levels of 0.8 +/- 0.1, 5.5 +/- 0.5, and 86 +/- 8 nmol/L had no effect on mortality, but reduced infarct size to 90 +/- 10% (P = 0.41), 67 +/- 7% (P = 0.005), and 82 +/- 7% (P = 0.13), respectively relative to vehicle-treated myocardial infarction rats (100 +/- 12%). In contrast to what was predicted, our data demonstrates that rotigaptide treatment was associated with a significant infarct size reduction. We conclude that whereas treatment with non-selective inhibitors of gap junction intercellular communication cause a reduction in infarct size, this information cannot be extrapolated to the effects of compounds that selectively increase gap junction intercellular communication.

  8. Electrical characterization of commercial NPN bipolar junction transistors under neutron and gamma irradiation

    Directory of Open Access Journals (Sweden)

    OO Myo Min

    2014-01-01

    Full Text Available Electronics components such as bipolar junction transistors, diodes, etc. which are used in deep space mission are required to be tolerant to extensive exposure to energetic neutrons and ionizing radiation. This paper examines neutron radiation with pneumatic transfer system of TRIGA Mark-II reactor at the Malaysian Nuclear Agency. The effects of the gamma radiation from Co-60 on silicon NPN bipolar junction transistors is also be examined. Analyses on irradiated transistors were performed in terms of the electrical characteristics such as current gain, collector current and base current. Experimental results showed that the current gain on the devices degraded significantly after neutron and gamma radiations. Neutron radiation can cause displacement damage in the bulk layer of the transistor structure and gamma radiation can induce ionizing damage in the oxide layer of emitter-base depletion layer. The current gain degradation is believed to be governed by the increasing recombination current in the base-emitter depletion region.

  9. Enteropathogenic E. coli: breaking the intestinal tight junction barrier [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Anand Prakash Singh

    2016-05-01

    Full Text Available Enteropathogenic E. coli (EPEC causes acute intestinal infections in infants in the developing world. Infection typically spreads through contaminated food and water and leads to severe, watery diarrhea. EPEC attaches to the intestinal epithelial cells and directly injects virulence factors which modulate multiple signaling pathways leading to host cell dysfunction. However, the molecular mechanisms that regulate the onset of diarrhea are poorly defined. A major target of EPEC is the host cell tight junction complex which acts as a barrier and regulates the passage of water and solutes through the paracellular space. In this review, we focus on the EPEC effectors that target the epithelial barrier, alter its functions and contribute to leakage through the tight junctions.

  10. Negative differential thermal conductance and thermal rectification effects across a graphene-based superconducting junction

    Science.gov (United States)

    Zhou, Xingfei; Zhang, Zhi

    2016-05-01

    We study the heat transport in a graphene-based normal-superconducting junction by solving the Bogoliubov-de Gennes (BdG) equation. There are two effects, the competitive and cooperative effects, which come from the interaction between the temperature-dependent energy-gap function in the superconducting region and the occupation difference of quasiparticles. It is found that the competitive effect can not only bring the negative differential thermal conductance effect but also the thermal rectification effect. By contrast, the cooperative effect just causes the thermal rectification effect. Furthermore, the thermal rectification ratio and the magnitude of heat current should be seen as two inseparable signs for characterizing the thermal rectification effect. These discoveries can add more application for the graphene-based superconducting junction, such as heat diode and heat transistor, at cryogenic temperatures.

  11. Large eddy simulation on thermal fluid mixing in a T-junction piping system

    Energy Technology Data Exchange (ETDEWEB)

    Selvam, P. Karthick; Kulenovic, R.; Laurien, E. [Stuttgart Univ. (Germany). Inst fuer Kernenergie und Energiesysteme (IKE)

    2014-11-15

    High cycle thermal fatigue damage caused in piping systems is an important problem encountered in the context of nuclear safety and lifetime management of a Nuclear Power Plant (NPP). The T-junction piping system present in the Residual Heat Removal System (RHRS) is more vulnerable to thermal fatigue cracking. In this numerical study, thermal mixing of fluids at temperature difference (?T) of 117 K between the mixing fluids is analyzed. Large Eddy Simulation (LES) is performed with conjugate heat transfer between the fluid and structure. LES is performed based on the Fluid-Structure Interaction (FSI) test facility at University of Stuttgart. The results show an intense turbulent mixing of fluids downstream of T-junction. Amplitude of temperature fluctuations near the wall region and its corresponding frequency distribution is analyzed. LES is performed using commercial CFD software ANSYS CFX 14.0.

  12. MgB2 tunnel junctions and SQUIDs

    NARCIS (Netherlands)

    Brinkman, A.; Rowell, J.M.

    2007-01-01

    Recent advances in the realization and understanding of MgB2 tunnel junctions and SQUIDs are surveyed. High quality MgB2 junctions with suitable tunnel barriers have been realized based on both oriented and epitaxial thin MgB2 films. Multiband transport properties, such as the existence of two energ

  13. Craniovertebral Junction Instability in the Setting of Chiari I Malformation.

    Science.gov (United States)

    Goldstein, Hannah E; Anderson, Richard C E

    2015-10-01

    This article addresses the key features, clinical presentation, and radiographic findings associated with craniovertebral junction instability in the setting of Chiari I malformation. It further discusses surgical technique for treating patients with Chiari I malformation with concomitant craniovertebral junction instability, focusing on modern posterior rigid instrumentation and fusion techniques.

  14. Parametric excitation of plasma oscillations in a Josephson tunnel junction

    DEFF Research Database (Denmark)

    Bak, Christen Kjeldahl; Kofoed, Bent; Pedersen, Niels Falsig

    1975-01-01

    Experimental evidence for subharmonic parametric excitation of plasma oscillations in Josephson tunnel junctions is presented. The experiments described are performed by measuring the microwave power necessary to switch a Josephson−tunnel junction biased in the zero−voltage state to a finite−volt......−voltage state. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  15. Shapiro and parametric resonances in coupled Josephson junctions

    Science.gov (United States)

    Gaafar, Ma A.; Shukrinov, Yu M.; Foda, A.

    2012-11-01

    The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We compare the current-voltage characteristics for a stack of coupled Josephson junctions under external irradiation calculated in the framework of CCJJ and CCJJ+DC models.

  16. Microwave phase locking of Josephson-junction fluxon oscillators

    DEFF Research Database (Denmark)

    Salerno, M.; Samuelsen, Mogens Rugholm; Filatrella, G.;

    1990-01-01

    -dimensional functional map. Phase-locked states correspond to fixed points of the map. For junctions of in-line geometry, the existence and stability of such fixed points can be studied analytically. Study of overlap-geometry junctions requires the numerical inversion of a functional equation, but the results...

  17. Josephson junctions in high-T/sub c/ superconductors

    Science.gov (United States)

    Falco, C.M.; Lee, T.W.

    1981-01-14

    The invention includes a high T/sub c/ Josephson sperconducting junction as well as the method and apparatus which provides the junction by application of a closely controlled and monitored electrical discharge to a microbridge region connecting two portions of a superconducting film.

  18. Junction leakage measurements with micro four-point probes

    DEFF Research Database (Denmark)

    Lin, Rong; Petersen, Dirch Hjorth; Wang, Fei

    2012-01-01

    We present a new, preparation-free method for measuring the leakage current density on ultra-shallow junctions. The junction leakage is found by making a series of four-point sheet resistance measurements on blanket wafers with variable electrode spacings. The leakage current density is calculate...

  19. How good are one-dimensional Josephson junction models?

    DEFF Research Database (Denmark)

    Lomdahl, P. S.; Olsen, O.H.; Eilbeck, J. C.

    1985-01-01

    A two-dimensional model of Josephson junctions of overlap type is presented and shown to reduce to the usual one-dimensional (1D) model in the limit of a very narrow junction. Comparisons between the stability limits for fluxon reflection obtained from the two models suggest that the many results...

  20. Relaxation towards phase-locked dynamics in long Josephson junctions

    DEFF Research Database (Denmark)

    Salerno, M.; Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    1995-01-01

    We study the relaxation phenomenon towards phase-locked dynamics in long Josephson junctions. In particular the dependence of the relaxation frequency for the equal time of flight solution on the junction parameters is derived. The analysis is based on a phase-locked map and is compared with dire...

  1. Processing of Superconductor-Normal-Superconductor Josephson Edge Junctions

    Science.gov (United States)

    Kleinsasser, A. W.; Barner, J. B.

    1997-01-01

    The electrical behavior of epitaxial superconductor-normal-superconductor (SNS) Josephson edge junctions is strongly affected by processing conditions. Ex-situ processes, utilizing photoresist and polyimide/photoresist mask layers, are employed for ion milling edges for junctions with Yttrium-Barium-Copper-Oxide (YBCO) electrodes and primarily Co-doped YBCO interlayers.

  2. 75 FR 76294 - Radio Broadcasting Services: Pacific Junction, IA

    Science.gov (United States)

    2010-12-08

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 Radio Broadcasting Services: Pacific Junction, IA AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: The staff deletes FM Channel 299C2 at Pacific Junction,...

  3. Shunted-Josephson-junction model. I. The autonomous case

    DEFF Research Database (Denmark)

    Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

    1977-01-01

    of the junction behavior in different regions of the parameter space. Approximate formulas are given for the parameter-space decomposition into regions of qualitatively different junction behavior corroborated by the associated-phase plane portraits and also approximate expressions for the corresponding dc...

  4. Gap junction protein connexin-43 interacts directly with microtubules

    NARCIS (Netherlands)

    Giepmans, B N; Verlaan, I; Hengeveld, T; Janssen, H; Calafat, J; Falk, M M; Moolenaar, W H

    2001-01-01

    Gap junctions are specialized cell-cell junctions that mediate intercellular communication. They are composed of connexin proteins, which form transmembrane channels for small molecules [1, 2]. The C-terminal tail of connexin-43 (Cx43), the most widely expressed connexin member, has been implicated

  5. Septal Junctions in Filamentous Heterocyst-Forming Cyanobacteria.

    Science.gov (United States)

    Flores, Enrique; Herrero, Antonia; Forchhammer, Karl; Maldener, Iris

    2016-02-01

    In the filaments of heterocyst-forming cyanobacteria, septal junctions that traverse the septal peptidoglycan join adjacent cells, allowing intercellular communication. Perforations in the septal peptidoglycan have been observed, and proteins involved in the formation of such perforations and putative protein components of the septal junctions have been identified, but their relationships are debated.

  6. Vortex dynamics in Josephson ladders with II-junctions

    DEFF Research Database (Denmark)

    Kornev, Victor K.; Klenov, N. V.; Oboznov, V.A.;

    2004-01-01

    Both experimental and numerical studies of a self-frustrated triangular array of pi-junctions are reported. The array of SFS Josephson junctions shows a transition to the pi-state and self-frustration with a decrease in temperature. This manifests itself in a half-period shift of the bias critica...

  7. Determination of Relaxation Time of a Josephson Tunnel Junction

    Institute of Scientific and Technical Information of China (English)

    WEN Xue-Da; YU Yang

    2008-01-01

    We propose a non-stationary method to measure the energy relaxation time of Josephson tunnel junctions from microwave enhanced escape phenomena.Compared with the previous methods,our method possesses simple and accurate features.Moreover,having determined the energy relaxation time,we can further obtain the coupling strength between the microwave source and the junction by changing the microwave power.

  8. Shunted-Josephson-junction model. II. The nonautonomous case

    DEFF Research Database (Denmark)

    Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

    1977-01-01

    The shunted-Josephson-junction model with a monochromatic ac current drive is discussed employing the qualitative methods of the theory of nonlinear oscillations. As in the preceding paper dealing with the autonomous junction, the model includes a phase-dependent conductance and a shunt capacitance...

  9. Conditions for synchronization in Josephson-junction arrays

    Energy Technology Data Exchange (ETDEWEB)

    Chernikov, A.A.; Schmidt, G. [Stevens Institute of Technology, Hoboken, NJ (United States)

    1995-12-31

    An effective perturbation theoretical method has been developed to study the dynamics of Josephson Junction series arrays. It is shown that the inclusion of Junction capacitances, often ignored, has a significant impact on synchronization. Comparison of analytic with computational results over a wide range of parameters shows excellent agreement.

  10. Genetic factors for nerve susceptibility to injuries-lessons from PMP22 deifciency

    Institute of Scientific and Technical Information of China (English)

    Jun Li

    2014-01-01

    Genetic factors may be learnt from families with gene mutations that render nerve-injury sus-ceptibility even to ordinary physical activities. A typical example is hereditary neuropathy with liability to pressure palsies (HNPP). HNPP is caused by a heterozygous deletion of PMP22 gene. PMP22 deficiency disrupts myelin junctions (such as tight junction and adherens junctions), leading to abnormally increased myelin permeability that explains the nerve susceptibility to injury. This ifnding should motivate investigators to identify additional genetic factors contribut-ing to nerve vulnerability of injury.

  11. Schottky barrier modulation of metal/4H-SiC junction with thin interface spacer driven by surface polarization charge on 4H-SiC substrate

    Science.gov (United States)

    Choi, Gahyun; Yoon, Hoon Hahn; Jung, Sungchul; Jeon, Youngeun; Lee, Jung Yong; Bahng, Wook; Park, Kibog

    2015-12-01

    The Au/Ni/Al2O3/4H-SiC junction with the Al2O3 film as a thin spacer layer was found to show the electrical characteristics of a typical rectifying Schottky contact, which is considered to be due to the leakiness of the spacer layer. The Schottky barrier of the junction was measured to be higher than an Au/Ni/4H-SiC junction with no spacer layer. It is believed that the negative surface bound charge originating from the spontaneous polarization of 4H-SiC causes the Schottky barrier increase. The use of a thin spacer layer can be an efficient experimental method to modulate Schottky barriers of metal/4H-SiC junctions.

  12. Parametric resonance in the system of long Josephson junctions

    Science.gov (United States)

    Rahmonov, I. R.; Shukrinov, Yu. M.; Irie, A.

    2014-08-01

    The phase dynamics of the system of long Josephson junctions whose length exceeds the Josephson penetration depth has been studied. The possibility of the appearance of a longitudinal plasma wave and parametric resonance has been demonstrated. Both inductive and capacitive couplings between Josephson junctions have been taken into account in the calculations. The current-voltage characteristics, as well as time evolution of the spatial distribution of the electric charge in superconducting layers and the magnetic field, have been calculated in all Josephson junctions of the system. The coexistence of the longitudinal plasma wave and fluxon states has been observed in the region of parametric resonance beginning with a certain length of the Josephson junction. This indicates the appearance of a new unique collective excitation in the system of coupled Josephson junctions, namely, a composite state of the Josephson current, electric field, and vortex magnetic field.

  13. Design of Steerable Wavelets to Detect Multifold Junctions.

    Science.gov (United States)

    Püspöki, Zsuzsanna; Uhlmann, Virginie; Vonesch, Cédric; Unser, Michael

    2016-02-01

    We propose a framework for the detection of junctions in images. Although the detection of edges and key points is a well examined and described area, the multiscale detection of junction centers, especially for odd orders, poses a challenge in pattern analysis. The goal of this paper is to build optimal junction detectors based on 2D steerable wavelets that are polar-separable in the Fourier domain. The approaches we develop are general and can be used for the detection of arbitrary symmetric and asymmetric junctions. The backbone of our construction is a multiscale pyramid with a radial wavelet function where the directional components are represented by circular harmonics and encoded in a shaping matrix. We are able to detect M -fold junctions in different scales and orientations. We provide experimental results on both simulated and real data to demonstrate the effectiveness of the algorithm.

  14. Observation of supercurrent in graphene-based Josephson junction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Libin; Li, Sen; Kang, Ning [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Xu, Chuan; Ren, Wencai [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-07-01

    Josephson junctions with a normal metal region sandwiched between two superconductors (S) are known as superconductor- normal-superconductor (SNS) structures. It has attracted significant attention especially when changing the normal metal with graphene, which allow for high tunability with the gate voltage and to study the proximity effect of the massless Dirac fermions. Here we report our work on graphene-based Josephson junction with a new two dimensional superconductor crystal, which grown directly on graphene, as superconducting electrodes. At low temperature, we observer proximity effect induced supercurrent flowing through the junction. The temperature and the magnetic field dependences of the critical current characteristics of the junction are also studied. The critical current exhibits a Fraunhofer-type diffraction pattern against magnetic field. Our experiments provided a new route of fabrication of graphene-based Josephson junction.

  15. Low conductance of nickel atomic junctions in hydrogen atmosphere

    Science.gov (United States)

    Li, Shuaishuai; Xie, Yi-Qun; Hu, Yibin

    2017-08-01

    The low conductance of nickel atomic junctions in the hydrogen environment is studied using the nonequilibrium Green's function theory combined with first-principles calculations. The Ni junction bridged by a H2 molecule has a conductance of approximately 0.7 G 0. This conductance is contributed by the anti-bonding state of the H2 molecule, which forms a bonding state with the 3 d orbitals of the nearby Ni atoms. In contrast, the Ni junction bridged by the two single H atoms has a conductance of approximately 1 G 0, which is weakly spin-polarized. The spin-up channels were found to contribute mostly to the conductance at a small junction gap, while the spin-down channels play a dominant role at a larger junction gap.

  16. The current-phase relation in HTS Josephson junctions

    Science.gov (United States)

    Il'ichev, E.; Zakosarenko, V.; Ijsselsteijn, R. P. J.; Schultze, V.; Meyer, H.-G.; Hoenig, H. E.

    The current-phase relation of YBa2Cu3O7-x step-edge as well as 24° and 45° grain boundary Josephson junctions has been investigated experimentally. The junctions were incorporated into a washer-shaped superconducting ring with inductance L≈80-300 pH. The ring was inductively coupled to a tank circuit with a resonance frequency 9…40 MHz. The current-phase relation was obtained from the measurement of the impedance of the phase-biased junction. It is shown, that experimentally observed deviations from harmonic behavior of the apparent current-phase relation for step-edge and 24° grain boundary junctions can be explained by the influence of thermal noise. The current-phase relation of 45° grain boundary junctions was found to be extremely non-harmonic. The reasons of this unusual behavior are discussed.

  17. Glial connexins and gap junctions in CNS inflammation and disease.

    Science.gov (United States)

    Kielian, Tammy

    2008-08-01

    Gap junctions facilitate direct cytoplasmic communication between neighboring cells, facilitating the transfer of small molecular weight molecules involved in cell signaling and metabolism. Gap junction channels are formed by the joining of two hemichannels from adjacent cells, each composed of six oligomeric protein subunits called connexins. Of paramount importance to CNS homeostasis are astrocyte networks formed by gap junctions, which play a critical role in maintaining the homeostatic regulation of extracellular pH, K+, and glutamate levels. Inflammation is a hallmark of several diseases afflicting the CNS. Within the past several years, the number of publications reporting effects of cytokines and pathogenic stimuli on glial gap junction communication has increased dramatically. The purpose of this review is to discuss recent observations characterizing the consequences of inflammatory stimuli on homocellular gap junction coupling in astrocytes and microglia as well as changes in connexin expression during various CNS inflammatory conditions.

  18. Fixed-gap tunnel junction for reading DNA nucleotides.

    Science.gov (United States)

    Pang, Pei; Ashcroft, Brian Alan; Song, Weisi; Zhang, Peiming; Biswas, Sovan; Qing, Quan; Yang, Jialing; Nemanich, Robert J; Bai, Jingwei; Smith, Joshua T; Reuter, Kathleen; Balagurusamy, Venkat S K; Astier, Yann; Stolovitzky, Gustavo; Lindsay, Stuart

    2014-12-23

    Previous measurements of the electronic conductance of DNA nucleotides or amino acids have used tunnel junctions in which the gap is mechanically adjusted, such as scanning tunneling microscopes or mechanically controllable break junctions. Fixed-junction devices have, at best, detected the passage of whole DNA molecules without yielding chemical information. Here, we report on a layered tunnel junction in which the tunnel gap is defined by a dielectric layer, deposited by atomic layer deposition. Reactive ion etching is used to drill a hole through the layers so that the tunnel junction can be exposed to molecules in solution. When the metal electrodes are functionalized with recognition molecules that capture DNA nucleotides via hydrogen bonds, the identities of the individual nucleotides are revealed by characteristic features of the fluctuating tunnel current associated with single-molecule binding events.

  19. UK combat-related pelvic junctional vascular injuries 2008-2011: implications for future intervention.

    Science.gov (United States)

    Walker, N M; Eardley, W; Clasper, J C

    2014-10-01

    In a recent publication, 297 of 6450 (4.6%) military coalition deaths over ten years were reported to be due to junctional bleeding. The authors suggested that some of these deaths could have been avoided with a junctional haemorrhage control device. Prospectively collected data on all injuries sustained in Afghanistan by UK military personnel from 1 August 2008 to 31 July 2011 period were reviewed, using the UK Joint Theatre Trauma Registry. All fatalities with significant pelvic injuries were identified and analysed, and the cause of death established to assess the potential role for a junctional haemorrhage control device. Significant upper thigh, groin or pelvic injuries were recorded in 124 casualties, of which 93 died. Of these the pelvic injury was the cause of death in 37, but only 1 casualty with potentially survivable injuries was identified where death was due to a vascular injury below the inguinal ligament, not controlled by a CAT. This represents vascular injury between the aortic bifurcation and the inguinal ligament. Eight of these survived to a medical facility but subsequently died of their wounds. These represent a subset in which vascular control proximal to the inguinal ligament could have altered the outcome. Some potentially survivable deaths due to exsanguination may be amenable to proximal vascular control. Our study does not substantiate previous conclusions that this can be achieved through use of a groin junctional tourniquet. We believe there may be a role for more proximal vascular control of pelvic bleeding, and this merits further research. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Scattering form factors for self-assembled network junctions

    Science.gov (United States)

    Foster, T.; Safran, S. A.; Sottmann, T.; Strey, R.

    2007-11-01

    The equilibrium microstructures in microemulsions and other self-assembled systems show complex, connected shapes such as symmetric bicontinuous spongelike structures and asymmetric bicontinuous networks formed by cylinders interconnected at junctions. In microemulsions, these cylinder network microstructures may mediate the structural transition from a spherical or globular phase to the bicontinuous microstructure. To understand the structural and statistical properties of such cylinder network microstructures as measured by scattering experiments, models are needed to extract the real-space structure from the scattering data. In this paper, we calculate the scattering functions appropriate for cylinder network microstructures. We focus on such networks that contain a high density of network junctions that connect the cylindrical elements. In this limit, the network microstructure can be regarded as an assembly of randomly oriented, closed packed network junctions (i.e., the cylinder scattering contributions are neglected). Accordingly, the scattering spectrum of the network microstructure can be calculated as the product of the junction number density, the junction form factor, which describes the scattering from the surface of a single junction, and a structure factor, which describes the local correlations of different junctions due to junction interactions (including their excluded volume). This approach is applied to analyze the scattering data from a bicontinuous microemulsion with equal volumes of water and oil. In a second approach, we included the cylinder scattering contribution in the junction form factor by calculating the scattering intensity of Y junctions to which three rods with spherical cross section are attached. The respective theoretical predictions are compared with results of neutron scattering measurements on a water-in-oil microemulsion with a connected microstructure.

  1. Influence of Coupling between Junctions on Breakpoint Current in Intrinsic Josephson Junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Mahfouzi, F.

    2007-04-01

    We study theoretically the current-voltage characteristics of intrinsic Josephson junctions in high-Tc superconductors. An oscillation of the breakpoint current on the outermost branch as a function of coupling α and dissipation β parameters is found. We explain this oscillation as a result of the creation of longitudinal plasma waves at the breakpoint with different wave numbers. We demonstrate the commensurability effect and predict a group behavior of the current-voltage characteristics for the stacks with a different number of junctions. A method to determine the wave number of longitudinal plasma waves from α and β dependence of the breakpoint current is suggested. We model the α and β dependence of the breakpoint current and obtain good agreement with the results of the simulation.

  2. Ruptured venous aneurysm of cervicomedullary junction

    Directory of Open Access Journals (Sweden)

    Ashish Aggarwal

    2014-01-01

    Full Text Available Background: Ruptured venous aneurysm is often seen with arterio-venous malformation (AVM or developmental venous anomaly (DVA. However, isolated venous aneurysm is unusual. Case Description: We present a case of ruptured venous aneurysm that presented with subarachnoid hemorrhage (SAH and intraventricular hemorrhage (IVH. Digital substraction angiography (DSA revealed a saccular contrast filling pouch in the left lateral aspect of cervicomedullary junction (CMJ. Endovascular intervention was not a viable option. During surgery, a saccular pliable structure approx. 1.5 Χ 1 cm was found in the subarachnoid space that was clipped and excised. There were no arterial feeders, no evidence of surrounding AVM, and no dilated perimedullary vein. Conclusion: This is perhaps the first reported case of ruptured venous aneurysm (without associated AVM of CMJ, which was successfully managed surgically. The possible etiologies remain an unnoticed head trauma or a congenital vessel wall abnormality. Surgically clipping and excision remains the treatment of choice for such lesion.

  3. Nonlinear nonequilibrium quasiparticle relaxation in Josephson junctions.

    Science.gov (United States)

    Krasnov, V M

    2009-11-27

    I solve numerically a full set of nonlinear kinetic balance equations for stacked Josephson junctions, which allows analysis of strongly nonequilibrium phenomena. It is shown that nonlinearity becomes significant already at very small disequilibrium. The following new, nonlinear effects are obtained: (i) At even-gap voltages V = 2nDelta/e (n = 2, 3, ...) nonequilibrium bosonic bands overlap. This leads to enhanced emission of Omega = 2Delta bosons and to the appearance of dips in tunnel conductance. (ii) A new type of radiative solution is found at strong disequilibrium. It is characterized by the fast stimulated relaxation of quasiparticles. A stack in this state behaves as a light emitting diode and directly converts electric power to boson emission, without utilization of the ac-Josephson effect. The phenomenon can be used for realization of a new type of superconducting cascade laser in the THz frequency range.

  4. Fully magnetic manganite spin filter tunnel junctions

    Science.gov (United States)

    Prasad, Bhagwati; Blamire, Mark G.

    2016-09-01

    In this paper we demonstrate spintronic devices which combine magnetic tunnel junctions with a spin-filtering tunnel barrier. These consist of an ultrathin ferromagnetic insulating barrier, Sm0.75Sr0.25MnO3, sandwiched between two ferromagnetic half-metallic manganite electrodes, La0.7Sr0.3MnO3 and La0.7Ca0.3MnO3, in a nanopillar structure. Depending on the relative magnetic configurations of barrier and electrode layers, three resistance states are well defined, which therefore represent a potential three-state memory concept. These results open the way for the development of spintronic devices by exploiting the many degrees of freedom of perovskite manganite heterostructure systems.

  5. Electron and Phonon Transport in Molecular Junctions

    DEFF Research Database (Denmark)

    Li, Qian

    transmission at the Fermi energy. We propose and analyze a way of using π   stacking to design molecular junctions to control heat transport. We develop a simple model system to identify optimal parameter regimes and then use density functional theory (DFT) to extract model parameters for a number of specific....... The system we are interested in here are π-stacked molecules connected with two semi-infinite leads. π-stacked aromatic rings, connected via π-π electronic coupling, provides a rather soft mechanical bridge while maintaining high electronic conductivity. We investigate electron transport...... and the thermoelectric response of five representative π-stacked systems. We find that the transmission and power factor are both enhanced by increasing the conjugation length or adding substituent groups. The local transmission shows that several extra paths are added by cyano groups, which increases the total...

  6. Electronic transport properties of phenylacetylene molecular junctions

    Institute of Scientific and Technical Information of China (English)

    Liu Wen; Cheng Jie; Yah Cui-Xia; Li Hai-Hong; Wang Yong-Juan; Liu De-Sheng

    2011-01-01

    Electronic transport properties of a kind of phenylacetylene compound- (4-mercaptophenyl)-phenylacetylene are calculated by the first-principles method in the framework of density functional theory and the nonequilibrium Green's function formalism.The molecular junction shows an obvious rectifying behaviour at a bias voltage larger than 1.0 V.The rectification effect is attributed to the asymmetry of the interface contacts.Moreover,at a bias voltage larger than 2.0 V,which is not referred to in a relevant experiment [Fang L,Park J Y,Ma H,Jan A K Y and Salmeron M 2007 Langmuir 23 11522],we find a negative differential resistance phenomenon.The negative differential resistance effect may originate from the change of the delocalization degree of the molecular orbitais induced by the bias.

  7. Functional oesophago-gastric junction imaging

    Institute of Scientific and Technical Information of China (English)

    Barry P McMahon; Asbj(φ)rn M Drewes; Hans Gregersen

    2006-01-01

    Despite its role in disease there is still no definitive method to assess oesophago-gastric junction competence (OGJ). Traditionally the OGJ has been assessed using manometry with lower oesophageal sphincter pressure as the indicator. More recently this has been shown not to be a very reliable marker of sphincter function and competence against reflux.Disorders such as gastro-oesophageal reflux disease and to a lesser extend achalasia still effects a significant number of patients. This review looks at using a new technique known as impedance planimetry to profile the geometry and pressure in the OGJ during distension of a bag. The data gathered can be reconstructed into a dynamic representation of OGJ action. This has been shown to provide a useful representation of the OGJ and to show changes to the competence of the OGJ in terms of compliance and distensibility as a result of endoluminal therapy.

  8. Shot Noise in Ferromagnetic Superconductor Tunnel Junctions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, the superconducting order parameter and the energy spectrum of the Bogoliubov excitations are obtained from the Bogoliubov-de Gennes (BdG) equation for a ferromagnetic superconductor (FS). Taking into account the rough interface scattering effect, we calculate the shot noise and the differential conductance of the normal- metal insulator ferromagnetic superconductor junction. It is shown that the exchange energy Eh in FS can lead to splitting of the differential shot noise peaks and the conductance peaks. The energy difference between the two splitting peaks is equal to 2Eh. The rough interface scattering strength results in descent of conductance peaks and the shot noise-to-current ratio but increases the shot noise.

  9. Permanent junctional reciprocating tachycardia in a dog.

    Science.gov (United States)

    Santilli, Roberto A; Santos, Luis F N; Perego, Manuela

    2013-09-01

    A 5-year-old male English Bulldog was presented with a 1-year history of paroxysmal supraventricular tachycardia (SVT) partially responsive to amiodarone. At admission the surface ECG showed sustained runs of a narrow QRS complex tachycardia, with a ventricular cycle length (R-R interval) of 260 ms, alternating with periods of sinus rhythm. Endocardial mapping identified the electrogenic mechanism of the SVT as a circus movement tachycardia with retrograde and decremental conduction along a concealed postero-septal atrioventricular pathway (AP) and anterograde conduction along the atrioventricular node. These characteristics were indicative of a permanent junctional reciprocating tachycardia (PJRT). Radiofrequency catheter ablation of the AP successfully terminated the PJRT, with no recurrence of tachycardia on Holter monitoring at 12 months follow-up.

  10. Exotic Brane Junctions from F-theory

    CERN Document Server

    Kimura, Tetsuji

    2016-01-01

    Applying string dualities to F-theory, we obtain various $[p,q]$-branes whose constituents are standard branes of codimension two and exotic branes. We construct junctions of the exotic five-branes and their Hanany-Witten transitions associated with those in F-theory. In this procedure, we understand the monodromy of the single $5^2_2$-brane. We also find the objects which are sensitive to the branch cut of the $5^2_2$-brane. Considering the web of branes in the presence of multiple exotic five-branes analogous to the web of five-branes with multiple seven-branes, we obtain novel brane constructions for $SU(2)$ gauge theories with $n$ flavors and their superconformal limit with enhanced $E_{n+1}$ symmetry in five, four, and three dimensions. Hence, adapting the techniques of the seven-branes to the exotic branes, we will be able to construct F-theories in diverse dimensions.

  11. Operating modes of superconducting tunnel junction device

    Energy Technology Data Exchange (ETDEWEB)

    Maehata, Keisuke [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering

    1998-07-01

    In the Electrotechnical Laboratory, an Nb type superconducting tunnel junction (STJ) device with 200 x 200 sq. micron in area and super high quality was manufactured. By using 55-fe source, response of this large area STJ to X-ray was measured. In this measurement, two action modes with different output wave height from front amplifier were observed. Then, in this study, current-voltage feature of the element in each action mode was analyzed to elucidate a mechanism to form such two action modes. The feature was analyzed by using first order approximate solution on cavity resonance mode of Sine-Gordon equation. From the analytical results, it could be supposed that direction and magnitude of effective magnetic field penetrating into jointed area changed by an induction current effect owing to impressing speed of the magnetic field, which brings two different current-voltage features to make possible to observe two action modes with different pulse wave height. (G.K.)

  12. Studies of silicon pn junction solar cells

    Science.gov (United States)

    Lindholm, F. A.; Neugroschel, A.

    1977-01-01

    Modifications of the basic Shockley equations that result from the random and nonrandom spatial variations of the chemical composition of a semiconductor were developed. These modifications underlie the existence of the extensive emitter recombination current that limits the voltage over the open circuit of solar cells. The measurement of parameters, series resistance and the base diffusion length is discussed. Two methods are presented for establishing the energy bandgap narrowing in the heavily-doped emitter region. Corrections that can be important in the application of one of these methods to small test cells are examined. Oxide-charge-induced high-low-junction emitter (OCI-HLE) test cells which exhibit considerably higher voltage over the open circuit than was previously seen in n-on-p solar cells are described.

  13. Tantalum oxide barrier in magnetic tunnel junctions

    Institute of Scientific and Technical Information of China (English)

    Guanghua Yu; Tingting Ren; Wei Ji; Jiao Teng; Fengwu Zhu

    2004-01-01

    Tantalum as an insulating barrier can take the place of Al in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize the oxidation states of Ta barrier.The experimental results show that the chemical state of tantalum is pure Ta5+ and the thickness of the oxide is 1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usually used in MTJs to form an intermetallic compound,NiTa2. A magnetic "dead layer" could be produced in the NiFe/Ta interface. The "dead layer" is likely to influence the spinning electron transport and the magnetoresistance effect.

  14. Controlling local currents in molecular junctions

    CERN Document Server

    Yadalam, Hari Kumar

    2016-01-01

    The effect of non-equilibrium constraints and dephasing on the circulating currents in molecular junctions are analyzed. Circulating currents are manifestations of quantum effects and can be induced either by externally applied bias or an external magnetic field through the molecular system. In symmetric Aharonov-Bohm ring, bond currents have two contributions, bias driven and magnetic field driven. We analyze the competition between these two contributions and show that, as a consequence, current through one of the branches can be completely suppressed. We then study the effect of asymmetry (as a result of chemical substitution) on the current pathways inside the molecule and study asymmetry induced circulating currents (without magnetic field) by tuning the coupling strength of the substituent (at finite bias).

  15. Tunable Magnetic Proximity Effects in Graphene Junctions

    Science.gov (United States)

    Lazic, Predrag; Belashchenko, Kirill; Zutic, Igor

    2015-03-01

    The characteristic length of the magnetic proximity effects exceed the thickness of a graphene layer leading to an important, but typically overlooked, modifications of equilibrium and transport properties, as well as the implications for graphene spintronics. Using the first-principles studies that integrate a real space density functional theory (GPAW) with the state-of-the art boundary elements electrostatic code based on the Robin Hood method, we explore tunable electronic structure and magnetic proximity effects in the ferromagnet/insulator/graphene junctions. We show that the inclusion of a finite-size gate electrodes and van der Walls interaction lead to nontrivial effects that could also be important in other two-dimensional materials beyond graphene. Work supported by US ONR, NSF-DMR and Nebraska NSF MRSEC.

  16. Computation of flow through the oesophagogastric junction

    Institute of Scientific and Technical Information of China (English)

    Barry P McMahon; Karl D Odie; Kenneth W Moloney; Hans Gregersen

    2007-01-01

    Whilst methods exist to indirectly measure the effects of increased flow or gastro-oesophageal refluxing,they cannot quantitatively measure the amount of acid travelling back up into the oesophagus during reflux, nor can they indicate the flow rate through the oesophagogastric junction (OGJ). Since OGJ dysfunction affects flow it seems most appropriate to describe the geometry of the OGJ and its effect on the flow.A device known as the functional lumen imaging probe (FLIP) has been shown to reliably measure the geometry of and pressure changes in the OGJ. FLIP cannot directly measure flow but the data gathered from the probe can be used to model flow through the junction by using computational flow dynamics (CFD).CFD uses a set of equations known as the Navier-Stokes equations to predict flow patterns and is a technique widely used in engineering. These equations are complex and require appropriate assumptions to provide simplifications before useful data can be obtained. With the assumption that the cross-sectional areas obtained via FLIP are circular, the radii of these circles can be obtained. A cubic interpolation scheme can then be applied to give a high-resolution geometry for the OGJ.In the case of modelling a reflux scenario, it can be seen that at the narrowest section a jet of fluid squirts into the oesophagus at a higher velocity than the fluid surrounding it. This jet has a maximum velocity of almost 2 ms-1 that occurs where the OGJ is at its narrowest. This simple prediction of acid 'squirting' into the oesophagus illustrates how the use of numerical methods can be used to develop a better understanding of the OGJ. This initial work using CFD shows some considerable promise for the future.

  17. Influence of coupling between junctions on breakpoint current in intrinsic Josephson junctions

    OpenAIRE

    Shukrinov, Yu M.; Mahfouzi, F.

    2006-01-01

    We study theoretically the current-voltage characteristics of intrinsic Josephson junctions in high-$T_c$ superconductors. An oscillation of the breakpoint current on the outermost branch as a function of coupling $\\alpha$ and dissipation $\\beta$ parameters is found. We explain this oscillation as a result of the creation of longitudinal plasma waves at the breakpoint with different wave numbers. We demonstrate the commensurability effect and predict a group behavior of the current-voltage ch...

  18. Optical trapping of microparticles using silicon nitride waveguide junctions and tapered-waveguide junctions on an optofluidic chip.

    Science.gov (United States)

    Cai, Hong; Poon, Andrew W

    2012-10-01

    We study optical trapping of microparticles on an optofluidic chip using silicon nitride waveguide junctions and tapered-waveguide junctions. We demonstrate the trapping of single 1 μm-sized polystyrene particles using the evanescent field of waveguide junctions connecting a submicrometer-sized input-waveguide and a micrometer-sized output-waveguide. Particle trapping is localized in the vicinity of the junction. We also demonstrate trapping of one and two 1μm-sized polystyrene particles using tapered-waveguide junctions connecting a submicrometer-sized singlemode input-waveguide and a micrometer-sized multimode output-waveguide. Particle trapping occurs near the taper output end, the taper center and the taper input end, depending on the taper aspect ratio.

  19. Molecular signatures in the transport properties of molecular wire junctions: what makes a junction "molecular"?

    Science.gov (United States)

    Troisi, Alessandro; Ratner, Mark A

    2006-02-01

    The simplest component of molecular electronics consists of a single-molecule transport junction: a molecule sandwiched between source and drain electrodes, with or without a third gate electrode. In this Concept article, we focus on how molecules control transport in metal-electrode molecular junctions, and where the molecular signatures are to be found. In the situation where the molecule is relatively short and the gap between injection energy and molecular eigenstates is large, transport occurs largely by elastic tunneling, stochastic switching is common, and the vibronic signature can be found using inelastic electron tunneling spectroscopy (IETS). As the energy gaps for injection become smaller, one begins to see stronger molecular signatures - these include Franck-Condon-like structures in the current/voltage characteristic and strong vibronic interactions, which can lead to hopping behavior at the polaron limit. Conformational changes induced by the strong electric field lead to another strong manifestation of the molecular nature of the junction. We overview some of this mechanistic landscape, focusing on significant effects of switching (both stochastic and controlled by the electric field) and of molecular vibronic coupling.

  20. Mouse Hepatitis Virus Infection Remodels Connexin43-Mediated Gap Junction Intercellular Communication In Vitro and In Vivo.

    Science.gov (United States)

    Basu, Rahul; Banerjee, Kaveri; Bose, Abhishek; Das Sarma, Jayasri

    2015-12-16

    Gap junctions (GJs) form intercellular channels which directly connect the cytoplasm between neighboring cells to facilitate the transfer of ions and small molecules. GJs play a major role in the pathogenesis of infection-associated inflammation. Mutations of gap junction proteins, connexins (Cxs), cause dysmyelination and leukoencephalopathy. In multiple sclerosis (MS) patients and its animal model experimental autoimmune encephalitis (EAE), Cx43 was shown to be modulated in the central nervous system (CNS). The mechanism behind Cx43 alteration and its role in MS remains unexplored. Mouse hepatitis virus (MHV) infection-induced demyelination is one of the best-studied experimental animal models for MS. Our studies demonstrated that MHV infection downregulated Cx43 expression at protein and mRNA levels in vitro in primary astrocytes obtained from neonatal mouse brains. After infection, a significant amount of Cx43 was retained in endoplasmic reticulum/endoplasmic reticulum Golgi intermediate complex (ER/ERGIC) and GJ plaque formation was impaired at the cell surface, as evidenced by a reduction of the Triton X-100 insoluble fraction of Cx43. Altered trafficking and impairment of GJ plaque formation may cause the loss of functional channel formation in MHV-infected primary astrocytes, as demonstrated by a reduced number of dye-coupled cells after a scrape-loading Lucifer yellow dye transfer assay. Upon MHV infection, a significant downregulation of Cx43 was observed in the virus-infected mouse brain. This study demonstrates that astrocytic Cx43 expression and function can be modulated due to virus stress and can be an appropriate model to understand the basis of cellular mechanisms involved in the alteration of gap junction intercellular communication (GJIC) in CNS neuroinflammation. We found that MHV infection leads to the downregulation of Cx43 in vivo in the CNS. In addition, results show that MHV infection impairs Cx43 expression in addition to gap junction

  1. Measurement of Beta Particles Induced Electron-Hole Pairs Recombination in Depletion Region of GaAs PN Junction

    Institute of Scientific and Technical Information of China (English)

    CHEN Hai-Yang; JIANG Lan; LI Da-Rang

    2011-01-01

    PN junctions and schottky diodes are widely employed as electron-hole pair collectors in electron beam induced current (EBIC) techniques and betavoltaic batteries, in which the recombination in depletion regions is ignored.We measured the beta particles induced electron-hole pairs recombination in the depletion region of a GaAs P+ PN+ junction, based on comparisons between measured short currents and ideal values. The results show that only 20% electron-hole pairs in the depletion can be collected, causing the short current. This indicates an electron-hole pair diffusion length of 0.2μm in the depletion region. Hence, it is necessary to evaluate the recombination in the EBIC techniques and betavoltaic design.%@@ PN junctions and schottky diodes are widely employed as electron-hole pair collectors in electron beam induced current(EBIC) techniques and betavoltaic batteries,in which the recombination in depletion regions is ignored.We measured the beta particles induced electron-hole pairs recombination in the depletion region of a GaAs P+ PN+ junction,based on comparisons between measured short currents and ideal values.The results show that only 20% electron-hole pairs in the depletion can be collected,causing the short current.This indicates an electron-hole pair diffusion length of 0.2μm in the depletion region.Hence,it is necessary to evaluate the recombination in the EBIC techniques and betavoltaic design.

  2. Spin transport and dynamics in the F/N junction

    Science.gov (United States)

    Li, Hua; Bedell, Kevin

    2015-03-01

    We study the spin transport in the low temperature regime (often referred to as the precession-dominated regime) between a ferromagnetic Fermi liquid (FFL) and a normal metal metallic Fermi liquid (NFL), the F/N junction, which is considered one of the basic spintronic devices. In particular, we explore the propagation of spin waves and transport of magnetization through the interface of the F/N junction where non-equilibrium spin polarization is created on the normal metal side of the junction by spin injection. We calculate the probable spin wave modes in the precession-dominated regime on both sides of the junction especially on the NFL side where the system is out of equilibrium. Proper boundary conditions at the interface are introduced to establish the transport of the spin properties through the F/N junction. In the end, a possible transmission conduction electron spin resonance experiment is suggested on the F/N junction to see if the predicted spin wave modes could propagate through the junction.

  3. Solar cell junction temperature measurement of PV module

    KAUST Repository

    Huang, B.J.

    2011-02-01

    The present study develops a simple non-destructive method to measure the solar cell junction temperature of PV module. The PV module was put in the environmental chamber with precise temperature control to keep the solar PV module as well as the cell junction in thermal equilibrium with the chamber. The open-circuit voltage of PV module Voc is then measured using a short pulse of solar irradiation provided by a solar simulator. Repeating the measurements at different environment temperature (40-80°C) and solar irradiation S (200-1000W/m2), the correlation between the open-circuit voltage Voc, the junction temperature Tj, and solar irradiation S is derived.The fundamental correlation of the PV module is utilized for on-site monitoring of solar cell junction temperature using the measured Voc and S at a short time instant with open circuit. The junction temperature Tj is then determined using the measured S and Voc through the fundamental correlation. The outdoor test results show that the junction temperature measured using the present method, Tjo, is more accurate. The maximum error using the average surface temperature Tave as the junction temperature is 4.8 °C underestimation; while the maximum error using the present method is 1.3 °C underestimation. © 2010 Elsevier Ltd.

  4. High electronic couplings of single mesitylene molecular junctions

    Directory of Open Access Journals (Sweden)

    Yuki Komoto

    2015-12-01

    Full Text Available We report on an experimental analysis of the charge transport properties of single mesitylene (1,3,5-trimethylbenzene molecular junctions. The electronic conductance and the current–voltage characteristics of mesitylene molecules wired into Au electrodes were measured by a scanning tunnelling microscopy-based break-junction method at room temperature in a liquid environment. We found the molecular junctions exhibited two distinct conductance states with high conductance values of ca. 10−1G0 and of more than 10−3G0 (G0 = 2e2/h in the electronic conductance measurements. We further performed a statistical analysis of the current–voltage characteristics of the molecular junctions in the two states. Within a single channel resonant tunnelling model, we obtained electronic couplings in the molecular junctions by fitting the current–voltage characteristics to the single channel model. The origin of the high conductance was attributed to experimentally obtained large electronic couplings of the direct π-bonded molecular junctions (ca. 0.15 eV. Based on analysis of the stretch length of the molecular junctions and the large electronic couplings obtained from the I–V analysis, we proposed two structural models, in which (i mesitylene binds to the Au electrode perpendicular to the charge transport direction and (ii mesitylene has tilted from the perpendicular orientation.

  5. Gap-junction-mediated cell-to-cell communication.

    Science.gov (United States)

    Hervé, Jean-Claude; Derangeon, Mickaël

    2013-04-01

    Cells of multicellular organisms need to communicate with each other and have evolved various mechanisms for this purpose, the most direct and quickest of which is through channels that directly connect the cytoplasms of adjacent cells. Such intercellular channels span the two plasma membranes and the intercellular space and result from the docking of two hemichannels. These channels are densely packed into plasma-membrane spatial microdomains termed "gap junctions" and allow cells to exchange ions and small molecules directly. A hemichannel is a hexameric torus of junctional proteins around an aqueous pore. Vertebrates express two families of gap-junction proteins: the well-characterized connexins and the more recently discovered pannexins, the latter being related to invertebrate innexins ("invertebrate connexins"). Some gap-junctional hemichannels also appear to mediate cell-extracellular communication. Communicating junctions play crucial roles in the maintenance of homeostasis, morphogenesis, cell differentiation and growth control in metazoans. Gap-junctional channels are not passive conduits, as previously long regarded, but use "gating" mechanisms to open and close the central pore in response to biological stimuli (e.g. a change in the transjunctional voltage). Their permeability is finely tuned by complex mechanisms that have just begun to be identified. Given their ubiquity and diversity, gap junctions play crucial roles in a plethora of functions and their dysfunctions are involved in a wide range of diseases. However, the exact mechanisms involved remain poorly understood.

  6. High electronic couplings of single mesitylene molecular junctions.

    Science.gov (United States)

    Komoto, Yuki; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

    2015-01-01

    We report on an experimental analysis of the charge transport properties of single mesitylene (1,3,5-trimethylbenzene) molecular junctions. The electronic conductance and the current-voltage characteristics of mesitylene molecules wired into Au electrodes were measured by a scanning tunnelling microscopy-based break-junction method at room temperature in a liquid environment. We found the molecular junctions exhibited two distinct conductance states with high conductance values of ca. 10(-1) G 0 and of more than 10(-3) G 0 (G 0 = 2e (2)/h) in the electronic conductance measurements. We further performed a statistical analysis of the current-voltage characteristics of the molecular junctions in the two states. Within a single channel resonant tunnelling model, we obtained electronic couplings in the molecular junctions by fitting the current-voltage characteristics to the single channel model. The origin of the high conductance was attributed to experimentally obtained large electronic couplings of the direct π-bonded molecular junctions (ca. 0.15 eV). Based on analysis of the stretch length of the molecular junctions and the large electronic couplings obtained from the I-V analysis, we proposed two structural models, in which (i) mesitylene binds to the Au electrode perpendicular to the charge transport direction and (ii) mesitylene has tilted from the perpendicular orientation.

  7. Flicker (1/f) noise in tunnel junction DC SQUIDS

    Energy Technology Data Exchange (ETDEWEB)

    Koch, R.H.; Clarke, J.; Goubau, W.M.; Martinis, J.M.; Pegrum, C.M.; Van Harlingen, D.J.

    1983-04-01

    We have measured the spectral density of the 1/f voltage noise in current-biased resistively shunted Josephson tunnel junctions and dc SQUIDs. A theory in which fluctuations in the temperature give rise to fluctuations in the critical current and hence in the voltage predicts the magnitude of the noise quite accurately for junctions with areas of about 2 x 10/sup 4/ ..mu..m/sup 2/, but significantly overestimates the noise for junctions with areas of about 6 ..mu..m/sup 2/. DC SQUIDs fabricated from these two types of junctions exhibit substantially more 1/f voltage noise than would be predicted from a model in which the noise arises from critical current fluctuations in the junctions. This result was confirmed by an experiment involving two different bias current and flux modulation schemes, which demonstrated that the predominant 1/f voltage noise arises not from critical current fluctuations, but from some unknown source that can be regarded as an apparent 1/f flux noise. Measurements on five different configurations of dc SQUIDs fabricated with thin-film tunnel junctions and with widely varying areas, inductances, and junction capacitances show that the spectral density of the 1/f equivalent flux noise is roughtly constant, within a factor of three of (10/sup -10//f)phi/sup 2//sub 0/Hz/sup -1/. It is emphasized that 1/f flux noise may not be the predominant source of 1/f noise in SQUIDS fabricated with other technologies.

  8. Mechanical deformations of boron nitride nanotubes in crossed junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yadong; Chen, Xiaoming; Ke, Changhong, E-mail: cke@binghamton.edu [Department of Mechanical Engineering, State University of New York at Binghamton, Binghamton, New York 13902 (United States); Park, Cheol [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Fay, Catharine C. [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Stupkiewicz, Stanislaw [Institute of Fundamental Technological Research, Warsaw (Poland)

    2014-04-28

    We present a study of the mechanical deformations of boron nitride nanotubes (BNNTs) in crossed junctions. The structure and deformation of the crossed tubes in the junction are characterized by using atomic force microscopy. Our results show that the total tube heights are reduced by 20%–33% at the crossed junctions formed by double-walled BNNTs with outer diameters in the range of 2.21–4.67 nm. The measured tube height reduction is found to be in a nearly linear relationship with the summation of the outer diameters of the two tubes forming the junction. The contact force between the two tubes in the junction is estimated based on contact mechanics theories and found to be within the range of 4.2–7.6 nN. The Young's modulus of BNNTs and their binding strengths with the substrate are quantified, based on the deformation profile of the upper tube in the junction, and are found to be 1.07 ± 0.11 TPa and 0.18–0.29 nJ/m, respectively. Finally, we perform finite element simulations on the mechanical deformations of the crossed BNNT junctions. The numerical simulation results are consistent with both the experimental measurements and the analytical analysis. The results reported in this paper contribute to a better understanding of the structural and mechanical properties of BNNTs and to the pursuit of their applications.

  9. Association of visceral adiposity with oesophageal and junctional adenocarcinomas.

    LENUS (Irish Health Repository)

    Beddy, P

    2012-02-01

    BACKGROUND: Obesity is associated with an increased incidence of oesophageal and oesophagogastric junction adenocarcinoma, in particular Siewert types I and II. This study compared abdominal fat composition in patients with oesophageal\\/junctional adenocarcinoma with that in patients with oesophageal squamous cell carcinoma and gastric adenocarcinoma, and in controls. METHOD: In total, 194 patients (110 with oesophageal\\/junctional adenocarcinoma, 38 with gastric adenocarcinoma and 46 with oesophageal squamous cell carcinoma) and 90 matched control subjects were recruited. The abdominal fat area was assessed using computed tomography (CT), and the total fat area (TFA), visceral fat area (VFA) and subcutaneous fat area (SFA) were calculated. RESULTS: Patients with oesophageal\\/junctional adenocarcinoma had significantly higher TFA and VFA values compared with controls (both P < 0.001), patients with gastric adenocarcinoma (P = 0.013 and P = 0.006 respectively) and patients with oesophageal squamous cell carcinoma (both P < 0.001). For junctional tumours, the highest TFA and VFA values were seen in patients with Siewert type I tumours (respectively P = 0.041 and P = 0.033 versus type III; P = 0.332 and P = 0.152 versus type II). CONCLUSION: Patients with oesophageal\\/junctional adenocarcinoma, in particular oesophageal and Siewert type I junctional tumours, have greater CT-defined visceral adiposity than patients with gastric adenocarcinoma or oesophageal squamous cell carcinoma, or controls.

  10. Josephson radiation from InSb-nanowire junction

    Science.gov (United States)

    van Woerkom, David; Proutski, Alexander; Krivachy, Tamas; Bouman, Daniel; van Gulik, Ruben; Gul, Onder; Cassidy, Maja; Car, Diana; Bakkers, Erik; Kouwenhoven, Leo; Geresdi, Attila

    Semiconducting nanowire Josephson junctions has recently gained interest as building blocks for Majorana circuits and gate-tuneable superconducting qubits . Here we investigate the rich physics of the Andreev bound state spectrum of InSb nanowire junctions utilizing the AC Josephson relation 2eV_bias =hf . We designed and characterized an on-chip microwave circuit coupling the nanowire junction to an Al/AlOx/Al tunnel junction. The DC response of the tunnel junction is affected by photon-assisted quasiparticle current, which gives us the possibility to measure the radiation spectrum of the nanowire junction up to several tens of GHz in frequency. Our circuit design allows for voltage or phase biasing of the Josephson junction enabling direct mapping of Andreev bound states. We discuss our fabrication methods and choice of materials to achieve radiation detection up to a magnetic field of few hundred milliTesla, compatible with Majorana states in spin-orbit coupled nanowires. This work has been supported by the Netherlands Foundations FOM, Abstract NWO and Microsoft Corporation Station Q.

  11. Development of thin wraparound junction silicon solar cells

    Science.gov (United States)

    Ho, F.; Iles, P. A.

    1981-01-01

    The state of the art technologies was applied to fabricate 50 micro thick 2x4 cm, coplanar back contact (CBC) solar cells with AMO efficiency above 12%. A requirement was that the cells have low solar absorptance. A wraparound junction (WAJ) with wraparound metallization was chosen. This WAJ approach avoided the need for very complex fixturing, especially during rotation of the cells for providing adequate contacts over dielectric edge layers. The contact adhesion to silicon was considered better than to an insulator. It is indicated that shunt resistance caused by poor WAJ diode quality, and series resistance from the WAJ contact, give good cell performance. The cells developed reached 14 percent AMO efficiency (at 25 C), with solar absorptance values of 0.73. Space/cell environmental tests were performed on these cells and the thin CSC cells performed well. The optimized design configuration and process sequence were used to make 50 deliverable CBC cells. These cells were all above 12 percent efficiency and had an average efficiency of -13 percent. Results of environmental tests (humidity-temperature, thermal shock, and contact adherence) are also given.

  12. Tunable magnetoresistance in an asymmetrically coupled single-molecule junction

    Science.gov (United States)

    Warner, Ben; El Hallak, Fadi; Prüser, Henning; Sharp, John; Persson, Mats; Fisher, Andrew J.; Hirjibehedin, Cyrus F.

    2015-03-01

    Phenomena that are highly sensitive to magnetic fields can be exploited in sensors and non-volatile memories. The scaling of such phenomena down to the single-molecule level may enable novel spintronic devices. Here, we report magnetoresistance in a single-molecule junction arising from negative differential resistance that shifts in a magnetic field at a rate two orders of magnitude larger than Zeeman shifts. This sensitivity to the magnetic field produces two voltage-tunable forms of magnetoresistance, which can be selected via the applied bias. The negative differential resistance is caused by transient charging of an iron phthalocyanine (FePc) molecule on a single layer of copper nitride (Cu2N) on a Cu(001) surface, and occurs at voltages corresponding to the alignment of sharp resonances in the filled and empty molecular states with the Cu(001) Fermi energy. An asymmetric voltage-divider effect enhances the apparent voltage shift of the negative differential resistance with magnetic field, which inherently is on the scale of the Zeeman energy. These results illustrate the impact that asymmetric coupling to metallic electrodes can have on transport through molecules, and highlight how this coupling can be used to develop molecular spintronic applications.

  13. Atomistic simulations of highly conductive molecular transport junctions under realistic conditions

    KAUST Repository

    French, William R.

    2013-01-01

    We report state-of-the-art atomistic simulations combined with high-fidelity conductance calculations to probe structure-conductance relationships in Au-benzenedithiolate (BDT)-Au junctions under elongation. Our results demonstrate that large increases in conductance are associated with the formation of monatomic chains (MACs) of Au atoms directly connected to BDT. An analysis of the electronic structure of the simulated junctions reveals that enhancement in the s-like states in Au MACs causes the increases in conductance. Other structures also result in increased conductance but are too short-lived to be detected in experiment, while MACs remain stable for long simulation times. Examinations of thermally evolved junctions with and without MACs show negligible overlap between conductance histograms, indicating that the increase in conductance is related to this unique structural change and not thermal fluctuation. These results, which provide an excellent explanation for a recently observed anomalous experimental result [Bruot et al., Nat. Nanotechnol., 2012, 7, 35-40], should aid in the development of mechanically responsive molecular electronic devices. © 2013 The Royal Society of Chemistry.

  14. Detailed Observation of Cell Junction in Anodic Porous Alumina with Square Cells

    Science.gov (United States)

    Asoh, Hidetaka; Ono, Sachiko; Hirose, Tomohito; Takatori, Ikuo; Masuda, Hideki

    2004-09-01

    The local structure of a cell junction in anodic porous alumina with square cells was studied by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The initiation of a square lattice pattern, which is different from a normal hexagonal cell arrangement, induced the characteristic growth of a porous structure. The obtained oxide film was formed by a close-packed array of square cells following the initiation. The shape of the pores changed from circular to square corresponding to the transformation of the cell structure at the steady state. The incorporation of unoxidized aluminum into the oxide film and the generation of voids were observed at the fourfold point of the cell junction. The height of the protrusions of the aluminum substrate at the cell junction was considerably larger than that of protrusions formed in naturally occurring anodic porous alumina with hexagonal cells. These specific features were thought to be caused by the inhomogeneous distribution of current at the square pore base.

  15. Weak Fermi Level Pinning Effect in Schottky Junction of α-MoTe2

    Science.gov (United States)

    Nakaharai, Shu; Yamamoto, Mahito; Ueno, Keiji; Tsukagoshi, Kazuhito

    Difficulty in hole injection from metal contacts to transition metal dichalcogenide (TMDC) semiconductors has been one of the most serious issues in the application of these 2D materials to future nanoelectronics, which is caused by the strong Fermi level pinning effect in the metal/TMDC Schottky junction. In this work, we found that the holes can be injected efficiently from a large work function metal of Pt to α-molybdenum ditelluride (α-MoTe2; 2H-type), a TMDC semiconductor. The Schottky barrier height for holes at the Pt/ α-MoTe2 interface was extracted to be 40 meV by the temperature dependence of back-gate modulated currents under the flat band condition at the junction, while the Schottky barrier for electrons in the junction with a small work function metal of Ti was found to be 50 meV. Considering the difference in the work functions of Pt and Ti, the Fermi level pinning effect in α-MoTe2 was found to be much weaker than that in other TMDC semiconductors such as MoS2. These results open a way to the realization of complementary type circuits in the 2D materials for future low-power consumption electronics. This work was supported by JSPS KAKENHI Grant Numbers 15K06006, 25107004.

  16. Experimental observations of thermal mixing characteristics in T-junction piping

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Mei-Shiue, E-mail: chenms@mx.nthu.edu.tw; Hsieh, Huai-En; Ferng, Yuh-Ming; Pei, Bau-Shi

    2014-09-15

    Highlights: • The effects of flow velocity ratio on thermal mixing phenomenon are the major parameters. • The flow velocity ratio (V{sub b}/V{sub m}) is greater than 13.6, reverse flow occurs. • The flow velocity ratio is greater than 13.7, a “good” mixing quality is achieved. - Abstract: The T-junction piping is frequently used in many industrial applications, including the nuclear plants. For a pressurized water reactor (PWR), the emergency core cooling systems (ECCS) inject cold water into the primary loops if a loss-of-coolant accident (LOCA) happens. Inappropriate mixing of the two streams with significant temperature different at a junction may cause strong thermal stresses to the downstream structures in the reactor vessel. The downstream structures may be damaged. This study is an experimental investigation into the thermal mixing effect occurring at a T-junction. A small-scale test facility was established to observe the mixing effect of flows with different temperature. Thermal mixing effect with different flow rates in the main and branch pipes are investigated by measuring the temperature distribution along the main pipe. In test condition I, we found that lower main pipe flow rate leads to better mixing effect with constant branch pipe flow rate. And in conditions II and III, higher injection flow velocity would enhance the turbulence effect which results in better thermal mixing. The results will be useful for applications with mixing fluids with different temperature.

  17. A cephalometric method to diagnosis the craniovertebral junction abnormalities in osteogenesis imperfecta patients

    Science.gov (United States)

    Ríos-Rodenas, Mercedes; Gutiérrez-Díez, María-Pilar; Feijóo, Gonzalo; Mourelle, Maria-Rosa; Garcilazo, Mario; Ortega-Aranegui, Ricardo

    2015-01-01

    Osteogenesis imperfecta (OI) is a hereditary bone fragility disorder that in most patients is caused by mutations affecting collagen type I. Their typical oral and craneofacial characteristics (Dentinogenesis imperfecta type I and class III malocclusion), involve the dentist in the multidisciplinary team that treat these patients. It is usual to perform lateral skull radiographs for the orthodontic diagnosis. In addition, this radiograph is useful to analyse the junctional area between skull base and spine, that could be damaged in OI. Pathology in the craneovertebral junction (CVJ) is a serious complication of OI with a prevalence ranging from rare to 37%. To diagnosis early skull base anomalies in these patients, previously the neurological symptoms have been appear, we make a simple cephalometric analysis of the CVJ. This method has four measurements and one angle. Once we calculate the values of the OI patient, we compare the result with the mean and the standard deviations of an age-appropriate average in healthy controls. If the patient has a result more than 2,5 SDs above the age-appropriate average in healthy controls, we should to refer the patient to his/her pediatrician or neurologist. These doctors have to consider acquiring another diagnostic images to be used to determine cranial base measurements with more reliability. Thereby, dentists who treat these patients, must be aware of the normal radiological anatomy of the cervical spine on the lateral cephalogram. Key words:Osteogenesis imperfecta, craniovertebral junction, cephalometric. PMID:25810828

  18. CFD validation in OECD/NEA t-junction benchmark.

    Energy Technology Data Exchange (ETDEWEB)

    Obabko, A. V.; Fischer, P. F.; Tautges, T. J.; Karabasov, S.; Goloviznin, V. M.; Zaytsev, M. A.; Chudanov, V. V.; Pervichko, V. A.; Aksenova, A. E. (Mathematics and Computer Science); (Cambridge Univ.); (Moscow Institute of Nuclar Energy Safety)

    2011-08-23

    When streams of rapidly moving flow merge in a T-junction, the potential arises for large oscillations at the scale of the diameter, D, with a period scaling as O(D/U), where U is the characteristic flow velocity. If the streams are of different temperatures, the oscillations result in experimental fluctuations (thermal striping) at the pipe wall in the outlet branch that can accelerate thermal-mechanical fatigue and ultimately cause pipe failure. The importance of this phenomenon has prompted the nuclear energy modeling and simulation community to establish a benchmark to test the ability of computational fluid dynamics (CFD) codes to predict thermal striping. The benchmark is based on thermal and velocity data measured in an experiment designed specifically for this purpose. Thermal striping is intrinsically unsteady and hence not accessible to steady state simulation approaches such as steady state Reynolds-averaged Navier-Stokes (RANS) models.1 Consequently, one must consider either unsteady RANS or large eddy simulation (LES). This report compares the results for three LES codes: Nek5000, developed at Argonne National Laboratory (USA), and Cabaret and Conv3D, developed at the Moscow Institute of Nuclear Energy Safety at (IBRAE) in Russia. Nek5000 is based on the spectral element method (SEM), which is a high-order weighted residual technique that combines the geometric flexibility of the finite element method (FEM) with the tensor-product efficiencies of spectral methods. Cabaret is a 'compact accurately boundary-adjusting high-resolution technique' for fluid dynamics simulation. The method is second-order accurate on nonuniform grids in space and time, and has a small dispersion error and computational stencil defined within one space-time cell. The scheme is equipped with a conservative nonlinear correction procedure based on the maximum principle. CONV3D is based on the immersed boundary method and is validated on a wide set of the experimental

  19. Negative differential resistance in Josephson junctions coupled to a cavity

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Filatrella, G.; Pierro, V.

    2014-01-01

    or external – is often used. A cavity may also induce a negative differential resistance region at the lower side of the resonance frequency. We investigate the dynamics of Josephson junctions with a negative differential resistance in the quasi particle tunnel current, i.e. in the McCumber curve. We find......Regions with negative differential resistance can arise in the IV curve of Josephson junctions and this phenomenon plays an essential role for applications, in particular for THz radiation emission. For the measurement of high frequency radiation from Josephson junctions, a cavity – either internal...

  20. Temporal correlations and structural memory effects in break junction measurements

    DEFF Research Database (Denmark)

    Magyarkuti, A.; Lauritzen, Kasper Primdal; Balogh, Zoltan Imre

    2017-01-01

    that correlations between the opening and subsequent closing traces may indicate structural memory effects in atomic-sized metallic and molecular junctions. Applying these methods on measured and simulated gold metallic contacts as a test system, we show that the surface diffusion induced flattening of the broken......-molecule junctions, we demonstrate pronounced contact memory effects and recovery of the molecule for junctions breaking before atomic chains are formed. However, if chains are pulled the random relaxation of the chain and molecule after rupture prevents opening-closing correlations....

  1. Vortex structure in a long Josephson junction with two inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Andreeva, O.Yu. [Tumen Thermal Networks OAO ' TRGK' , Tobolsk 626150 (Russian Federation); Boyadjiev, T.L. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Shukrinov, Yu.M. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)], E-mail: shukrinv@theor.jinr.ru

    2007-09-01

    We study the vortex structure in the long Josephson junctions with one and two rectangular inhomogeneities in the barrier layer. In case of one inhomogeneity we demonstrate the existence of the asymmetric fluxon states. The disappearance of the mixed fluxon-antifluxon states is shown when the position of the inhomogeneity shifted to the end of the junction. In case of two inhomogeneities the change of the amplitude of Josephson current through the inhomogeneity in the end of the junction makes strong effect on the stability of the fluxon states and smoothes the maximums on the dependence 'critical current-magnetic field'.

  2. Vortex structure in a long Josephson junction with two inhomogeneities

    Science.gov (United States)

    Andreeva, O. Yu.; Boyadjiev, T. L.; Shukrinov, Yu. M.

    2007-09-01

    We study the vortex structure in the long Josephson junctions with one and two rectangular inhomogeneities in the barrier layer. In case of one inhomogeneity we demonstrate the existence of the asymmetric fluxon states. The disappearance of the mixed fluxon-antifluxon states is shown when the position of the inhomogeneity shifted to the end of the junction. In case of two inhomogeneities the change of the amplitude of Josephson current through the inhomogeneity in the end of the junction makes strong effect on the stability of the fluxon states and smoothes the maximums on the dependence “critical current-magnetic field”.

  3. Bloch inductance in small-capacitance Josephson junctions.

    Science.gov (United States)

    Zorin, A B

    2006-04-28

    We show that the electrical impedance of a small-capacitance Josephson junction also includes, in addition to the capacitive term -i/(omega)CB, an inductive term i(omega)LB. Similar to the known Bloch capacitance CB(q), the Bloch inductance LB(q) also depends periodically on the quasicharge, q, and its maximum value achieved at q=e(mod 2e) always exceeds the value of the Josephson inductance of this junction LJ(phi) at fixed phi=0. The effect of the Bloch inductance on the dynamics of a single junction and a one-dimensional array is described.

  4. Two new septate junctions in the phylum Coelenterata.

    Science.gov (United States)

    Green, C R; Flower, N E

    1980-04-01

    Freeze-fracture of fixed and unfixed tissue, lanthanum tracer and conventional thin-section studies have revealed 2 new types of septate junction in the class Anthozoa, phylum Coelenterata. These new junctions have the 15-18-nm intercellular spacing of all other described septate junctions and are found around the apical circumference of cells lining a lumen or outside edge. However, in freeze-fracture replicas and tangential views of lanthanum-impregnated tissue, they are seen to be quite different from other known septate junction types. One of the new junctions is found in endothelial tissue such as that lining the gut or the inside of the tentacles. In tangential view it is seen to consist of relatively short, straight, double septa, again with lateral projections. In feeeze-fracture of unfixed tissue, the junction consists of double rows of particles on the P face, the particles of one row being rounded, those of the other being elongated at right angles to the line of the septum. This dichotomy in particle size is unexpected, as the 2 halves of the septa as seen in tangential view are symmetrical. In freeze-fracture of fixed material the particle arrays remain on the P face and appear similar to those of unfixed material, but never as clear. In fixed tissue, some distortion had occurred and in extreme cases septa appear as a single broad jumbled row of particles. In this double septa junction, the rows of particles seen in freeze-fracture are occasionally seen to anastomose with a septum dividing into 2 and a third row of particles aligning with the 2 new septa to form their double particle rows. In both fixed and unfixed tissues, the E face of the junction consists of wide, shallow grooves. The second of the new junctions occurs in epithelial tissue, such as around the outer edge of sea-anemone tentacles, and consists of long wavy septa with lateral projections. In views where these projections appear longest, they arise predominantly from one side of the

  5. Externally pumped millimeter-wave Josephson-junction parametric amplifier

    DEFF Research Database (Denmark)

    Levinsen, M.T; Pedersen, Niels Falsig; Sørensen, Ole;

    1980-01-01

    A unified theory of the singly and doubly degenerate Josephson-junction parametric amplifier is presented. Experiments with single junctions on both amplifier modes at frequencies 10, 35, and 70 GHz are discussed. Low-noise temperature (∼100 K, single sideband (SSB)) and reasonable gain (∼8 d......B) were obtained at 35 GHz in the singly degenerate mode. On the basis of the theory and experiments, a general procedure for optimizing junction parameters is discussed and illustrated by the specific design of a 100-GHz amplifier....

  6. Junction temperature estimation for an advanced active power cycling test

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Jørgensen, S.

    2015-01-01

    estimation method using on-state VCE for an advanced active power cycling test is proposed. The concept of the advanced power cycling test is explained first. Afterwards the junction temperature estimation method using on-state VCE and current is presented. Further, the method to improve the accuracy......On-state collector-emitter voltage (VCE) is a good indicator to determine the wear-out condition of power device modules. Further, it is a one of the Temperature Sensitive Electrical Parameters (TSEPs) and thus can be used for junction temperature estimation. In this paper, the junction temperature...

  7. Turbulence-induced magnetic flux asymmetry at nanoscale junctions.

    Science.gov (United States)

    Bushong, Neil; Pershin, Yuriy; Di Ventra, Massimiliano

    2007-11-30

    It was recently predicted [J. Phys. Condens. Matter 18, 11059 (2006)] that turbulence of electron flow may develop at nonadiabatic nanoscale junctions under appropriate conditions. Here we show that such an effect leads to an asymmetric current-induced magnetic field on the two sides of an otherwise symmetric junction. We propose that measuring the fluxes ensuing from these fields across two surfaces placed at the two sides of the junction would provide direct and noninvasive evidence of the transition from laminar to turbulent electron flow. The flux asymmetry is predicted to first increase, reach a maximum, and then decrease with increasing current, i.e., with increasing amount of turbulence.

  8. Nonequilibrium and proximity effects in superconductor-normal metal junctions

    Science.gov (United States)

    Kauppila, V. J.; Nguyen, H. Q.; Heikkilä, T. T.

    2013-08-01

    We study the consequences of nonequilibrium heating and inverse proximity effect in normal metal-insulator-superconductor-insulator-normal metal (NISIN) junctions with a simple quasi-one-dimensional model. We especially focus on observables and parameter regions that are of interest in the design of SINIS coolers with quasiparticle traps. We present numerical results calculated by solving the Usadel equation and also present analytical approximations in two limiting cases: a short junction with a non-negligible resistance in both ends and a long junction with a transparent contact at one end.

  9. Gap junction modulation and its implications for heart function.

    Science.gov (United States)

    Kurtenbach, Stefan; Kurtenbach, Sarah; Zoidl, Georg

    2014-01-01

    Gap junction communication (GJC) mediated by connexins is critical for heart function. To gain insight into the causal relationship of molecular mechanisms of disease pathology, it is important to understand which mechanisms contribute to impairment of gap junctional communication. Here, we present an update on the known modulators of connexins, including various interaction partners, kinases, and signaling cascades. This gap junction network (GJN) can serve as a blueprint for data mining approaches exploring the growing number of publicly available data sets from experimental and clinical studies.

  10. Gap junction modulation and its implications for heart function

    Directory of Open Access Journals (Sweden)

    Stefan eKurtenbach

    2014-02-01

    Full Text Available Gap junction communication mediated by connexins is critical for heart function. To gain insight into the causal relationship of molecular mechanisms of disease pathology, it is important to understand which mechanisms contribute to impairment of gap junctional communication. Here, we present an update on the known modulators of connexins, including various interaction partners, kinases and signaling cascades. This gap junction network can serve as a blueprint for data mining approaches exploring the growing number of publicly available data sets from experimental and clinical studies.

  11. No junctional communication between epithelial cells in hydra

    DEFF Research Database (Denmark)

    de Laat, S W; Tertoolen, L G; Grimmelikhuijzen, C J

    1980-01-01

    junctions between epithelial cells of hydra. However, until now, there has been no report published on whether these junctions enable the epithelial cells to exchange molecules of small molecular weight, as has been described in other organisms. Therefore we decided to investigate the communicative...... properties of the junctional membranes by electrophysiological methods and by intracellular-dye iontophoresis. We report here that no electrotonic coupling is detectable between epithelial cells of Hydra attenuata in: (1) intact animals, (2) head-regenerating animals, (3) cell re-aggregates, and (4) hydra...

  12. Soft nanostructuring of YBCO Josephson junctions by phase separation.

    Science.gov (United States)

    Gustafsson, D; Pettersson, H; Iandolo, B; Olsson, E; Bauch, T; Lombardi, F

    2010-12-08

    We have developed a new method to fabricate biepitaxial YBa2 Cu3 O7-δ (YBCO) Josephson junctions at the nanoscale, allowing junctions widths down to 100 nm and simultaneously avoiding the typical damage in grain boundary interfaces due to conventional patterning procedures. By using the competition between the superconducting YBCO and the insulating Y2 BaCuO5 phases during film growth, we formed nanometer sized grain boundary junctions in the insulating Y2 BaCuO5 matrix as confirmed by high-resolution transmission electron microscopy. Electrical transport measurements give clear indications that we are close to probing the intrinsic properties of the grain boundaries.

  13. Dependence of transport properties in tunnel junction on boron doping

    Energy Technology Data Exchange (ETDEWEB)

    Shi, M.J.; Zeng, X.B.; Liu, S.Y.; Peng, W.B; Xiao, H.B; Liao, X.B.; Wang, Z.G.; Kong, G.L. [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2010-04-15

    Boron-doped hydrogenated silicon films with different gaseous doping ratio (B{sub 2}H{sub 6}/SiH{sub 4}) were fabricated as recombination p layers in tunnel junctions. The measurements of I-V characteristics of the junctions and transparency spectra of p layer indicated that the best gaseous doping ratio of the recombination layer is 0.04, which is correlated to the degradation of short range order (SRO) in the inserted p thin film. The junction with such recombination layer has small resistance, near ohmic contact. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Phosphorylation on Ser-279 and Ser-282 of connexin43 regulates endocytosis and gap junction assembly in pancreatic cancer cells

    Science.gov (United States)

    Johnson, Kristen E.; Mitra, Shalini; Katoch, Parul; Kelsey, Linda S.; Johnson, Keith R.; Mehta, Parmender P.

    2013-01-01

    The molecular mechanisms regulating the assembly of connexins (Cxs) into gap junctions are poorly understood. Using human pancreatic tumor cell lines BxPC3 and Capan-1, which express Cx26 and Cx43, we show that, upon arrival at the cell surface, the assembly of Cx43 is impaired. Connexin43 fails to assemble, because it is internalized by clathrin-mediated endocytosis. Assembly is restored upon expressing a sorting-motif mutant of Cx43, which does not interact with the AP2 complex, and by expressing mutants that cannot be phosphorylated on Ser-279 and Ser-282. The mutants restore assembly by preventing clathrin-mediated endocytosis of Cx43. Our results also document that the sorting-motif mutant is assembled into gap junctions in cells in which the expression of endogenous Cx43 has been knocked down. Remarkably, Cx43 mutants that cannot be phosphorylated on Ser-279 or Ser-282 are assembled into gap junctions only when connexons are composed of Cx43 forms that can be phosphorylated on these serines and forms in which phosphorylation on these serines is abolished. Based on the subcellular fate of Cx43 in single and contacting cells, our results document that the endocytic itinerary of Cx43 is altered upon cell–cell contact, which causes Cx43 to traffic by EEA1-negative endosomes en route to lysosomes. Our results further show that gap-junctional plaques formed of a sorting motif–deficient mutant of Cx43, which is unable to be internalized by the clathrin-mediated pathway, are predominantly endocytosed in the form of annular junctions. Thus the differential phosphorylation of Cx43 on Ser-279 and Ser-282 is fine-tuned to control Cx43’s endocytosis and assembly into gap junctions. PMID:23363606

  15. SLO BK Potassium Channels Couple Gap Junctions to Inhibition of Calcium Signaling in Olfactory Neuron Diversification.

    Science.gov (United States)

    Alqadah, Amel; Hsieh, Yi-Wen; Schumacher, Jennifer A; Wang, Xiaohong; Merrill, Sean A; Millington, Grethel; Bayne, Brittany; Jorgensen, Erik M; Chuang, Chiou-Fen

    2016-01-01

    The C. elegans AWC olfactory neuron pair communicates to specify asymmetric subtypes AWCOFF and AWCON in a stochastic manner. Intercellular communication between AWC and other neurons in a transient NSY-5 gap junction network antagonizes voltage-activated calcium channels, UNC-2 (CaV2) and EGL-19 (CaV1), in the AWCON cell, but how calcium signaling is downregulated by NSY-5 is only partly understood. Here, we show that voltage- and calcium-activated SLO BK potassium channels mediate gap junction signaling to inhibit calcium pathways for asymmetric AWC differentiation. Activation of vertebrate SLO-1 channels causes transient membrane hyperpolarization, which makes it an important negative feedback system for calcium entry through voltage-activated calcium channels. Consistent with the physiological roles of SLO-1, our genetic results suggest that slo-1 BK channels act downstream of NSY-5 gap junctions to inhibit calcium channel-mediated signaling in the specification of AWCON. We also show for the first time that slo-2 BK channels are important for AWC asymmetry and act redundantly with slo-1 to inhibit calcium signaling. In addition, nsy-5-dependent asymmetric expression of slo-1 and slo-2 in the AWCON neuron is necessary and sufficient for AWC asymmetry. SLO-1 and SLO-2 localize close to UNC-2 and EGL-19 in AWC, suggesting a role of possible functional coupling between SLO BK channels and voltage-activated calcium channels in AWC asymmetry. Furthermore, slo-1 and slo-2 regulate the localization of synaptic markers, UNC-2 and RAB-3, in AWC neurons to control AWC asymmetry. We also identify the requirement of bkip-1, which encodes a previously identified auxiliary subunit of SLO-1, for slo-1 and slo-2 function in AWC asymmetry. Together, these results provide an unprecedented molecular link between gap junctions and calcium pathways for terminal differentiation of olfactory neurons.

  16. Josephson effect in multiterminal superconductor-ferromagnet junctions coupled via triplet components

    Science.gov (United States)

    Moor, Andreas; Volkov, Anatoly F.; Efetov, Konstantin B.

    2016-03-01

    On the basis of the Usadel equation we study a multiterminal Josephson junction. This junction is composed by "magnetic" superconductors Sm, which have singlet pairing and are separated from the normal n wire by spin filters so that the Josephson coupling is caused only by fully polarized triplet components. We show that there is no interaction between triplet Cooper pairs with antiparallel total spin orientations. The presence of an additional singlet superconductor S attached to the n wire leads to a finite Josephson current IQ with an unusual current-phase relation. The density of states in the n wire for different orientations of spins of Cooper pairs is calculated. We derive a general formula for the current IQ in a multiterminal Josephson contact and apply this formula for analysis of two four-terminal Josephson junctions of different structures. It is shown in particular that both the "nematic" and the "magnetic" cases can be realized in these junctions. In a two-terminal structure with parallel filter orientations and in a three-terminal structure with antiparallel filter orientations of the "magnetic" superconductors with attached additional singlet superconductor, we find a nonmonotonic temperature dependence of the critical current. Also, in these structures, the critical current shows a Riedel peak like dependence on the exchange field in the "magnetic" superconductors. Although there is no current through the S/n interface due to orthogonality of the singlet and triplet components, the phase of the order parameter in the superconuctor S is shown to affect the Josephson current in a multiterminal structure.

  17. Pharmacological blockade of gap junctions induces repetitive surging of extracellular potassium within the locust CNS.

    Science.gov (United States)

    Spong, Kristin E; Robertson, R Meldrum

    2013-10-01

    The maintenance of cellular ion homeostasis is crucial for optimal neural function and thus it is of great importance to understand its regulation. Glial cells are extensively coupled by gap junctions forming a network that is suggested to serve as a spatial buffer for potassium (K(+)) ions. We have investigated the role of glial spatial buffering in the regulation of extracellular K(+) concentration ([K(+)]o) within the locust metathoracic ganglion by pharmacologically inhibiting gap junctions. Using K(+)-sensitive microelectrodes, we measured [K(+)]o near the ventilatory neuropile while simultaneously recording the ventilatory rhythm as a model of neural circuit function. We found that blockade of gap junctions with either carbenoxolone (CBX), 18β-glycyrrhetinic acid (18β-GA) or meclofenamic acid (MFA) reliably induced repetitive [K(+)]o surges and caused a progressive impairment in the ability to maintain baseline [K(+)]o levels throughout the treatment period. We also show that a low dose of CBX that did not induce surging activity increased the vulnerability of locust neural tissue to spreading depression (SD) induced by Na(+)/K(+)-ATPase inhibition with ouabain. CBX pre-treatment increased the number of SD events induced by ouabain and hindered the recovery of [K(+)]o back to baseline levels between events. Our results suggest that glial spatial buffering through gap junctions plays an essential role in the regulation of [K(+)]o under normal conditions and also contributes to a component of [K(+)]o clearance following physiologically elevated levels of [K(+)]o.

  18. The serine protease-mediated increase in intestinal epithelial barrier function is dependent on occludin and requires an intact tight junction.

    Science.gov (United States)

    Ronaghan, Natalie J; Shang, Judie; Iablokov, Vadim; Zaheer, Raza; Colarusso, Pina; Dion, Sébastien; Désilets, Antoine; Leduc, Richard; Turner, Jerrold R; MacNaughton, Wallace K

    2016-09-01

    Barrier dysfunction is a characteristic of the inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Understanding how the tight junction is modified to maintain barrier function may provide avenues for treatment of IBD. We have previously shown that the apical addition of serine proteases to intestinal epithelial cell lines causes a rapid and sustained increase in transepithelial electrical resistance (TER), but the mechanisms are unknown. We hypothesized that serine proteases increase barrier function through trafficking and insertion of tight junction proteins into the membrane, and this could enhance recovery of a disrupted monolayer after calcium switch or cytokine treatment. In the canine epithelial cell line, SCBN, we showed that matriptase, an endogenous serine protease, could potently increase TER. Using detergent solubility-based cell fractionation, we found that neither trypsin nor matriptase treatment changed levels of tight junction proteins at the membrane. In a fast calcium switch assay, serine proteases did not enhance the rate of recovery of the junction. In addition, serine proteases could not reverse barrier disruption induced by IFNγ and TNFα. We knocked down occludin in our cells using siRNA and found this prevented the serine protease-induced increase in TER. Using fluorescence recovery after photobleaching (FRAP), we found serine proteases induce a greater mobile fraction of occludin in the membrane. These data suggest that a functional tight junction is needed for serine proteases to have an effect on TER, and that occludin is a crucial tight junction protein in this mechanism.

  19. Calcium oxalate crystals induces tight junction disruption in distal renal tubular epithelial cells by activating ROS/Akt/p38 MAPK signaling pathway.

    Science.gov (United States)

    Yu, Lei; Gan, Xiuguo; Liu, Xukun; An, Ruihua

    2017-11-01

    Tight junction plays important roles in regulating paracellular transports and maintaining cell polarity. Calcium oxalate monohydrate (COM) crystals, the major crystalline composition of kidney stones, have been demonstrated to be able to cause tight junction disruption to accelerate renal cell injury. However, the cellular signaling involved in COM crystal-induced tight junction disruption remains largely to be investigated. In the present study, we proved that COM crystals induced tight junction disruption by activating ROS/Akt/p38 MAPK pathway. Treating Madin-Darby canine kidney (MDCK) cells with COM crystals induced a substantial increasing of ROS generation and activation of Akt that triggered subsequential activation of ASK1 and p38 mitogen-activated protein kinase (MAPK). Western blot revealed a significantly decreased expression of ZO-1 and occludin, two important structural proteins of tight junction. Besides, redistribution and dissociation of ZO-1 were observed by COM crystals treatment. Inhibition of ROS by N-acetyl-l-cysteine (NAC) attenuated the activation of Akt, ASK1, p38 MAPK, and down-regulation of ZO-1 and occludin. The redistribution and dissociation of ZO-1 were also alleviated by NAC treatment. These results indicated that ROS were involved in the regulation of tight junction disruption induced by COM crystals. In addition, the down-regulation of ZO-1 and occludin, the phosphorylation of ASK1 and p38 MAPK were also attenuated by MK-2206, an inhibitor of Akt kinase, implying Akt was involved in the disruption of tight junction upstream of p38 MAPK. Thus, these results suggested that ROS-Akt-p38 MAPK signaling pathway was activated in COM crystal-induced disruption of tight junction in MDCK cells.

  20. Magnetic domain wall engineering in a nanoscale permalloy junction

    Science.gov (United States)

    Wang, Junlin; Zhang, Xichao; Lu, Xianyang; Zhang, Jason; Yan, Yu; Ling, Hua; Wu, Jing; Zhou, Yan; Xu, Yongbing

    2017-08-01

    Nanoscale magnetic junctions provide a useful approach to act as building blocks for magnetoresistive random access memories (MRAM), where one of the key issues is to control the magnetic domain configuration. Here, we study the domain structure and the magnetic switching in the Permalloy (Fe20Ni80) nanoscale magnetic junctions with different thicknesses by using micromagnetic simulations. It is found that both the 90-° and 45-° domain walls can be formed between the junctions and the wire arms depending on the thickness of the device. The magnetic switching fields show distinct thickness dependencies with a broad peak varying from 7 nm to 22 nm depending on the junction sizes, and the large magnetic switching fields favor the stability of the MRAM operation.

  1. Manipulating Josephson junctions in thin-films by nearby vortices

    Energy Technology Data Exchange (ETDEWEB)

    Kogan, V G; Mints, R G

    2014-07-01

    It is shown that a vortex trapped in one of the banks of a planar edge-type Josephson junction in a narrow thin-film superconducting strip can change drastically the dependence of the junction critical current on the applied field, I-c(H). When the vortex is placed at certain discrete positions in the strip middle, the pattern I-c(H) has zero at H = 0 instead of the traditional maximum of '0-type' junctions. The number of these positions is equal to the number of vortices trapped at the same location. When the junction-vortex separation exceeds similar to W, the strip width, I-c(H) is no longer sensitive to the vortex presence. The same is true for any separation if the vortex approaches the strip edges. (C) 2014 Elsevier B.V. All rights reserved.

  2. Low-Cost Multi-Junction Photovoltaic Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed SBIR project will provide a pathway to dramatically reduce the cost of multi-junction solar cells. The project leverages a TRL6 micropackaging process...

  3. Static vortices in long Josephson junctions of exponentially varying width

    Science.gov (United States)

    Semerdjieva, E. G.; Boyadjiev, T. L.; Shukrinov, Yu. M.

    2004-06-01

    A numerical simulation is carried out for static vortices in a long Josephson junction with an exponentially varying width. At specified values of the parameters the corresponding boundary-value problem admits more than one solution. Each solution (distribution of the magnetic flux in the junction) is associated to a Sturm-Liouville problem, the smallest eigenvalue of which can be used, in a first approximation, to assess the stability of the vortex against relatively small spatiotemporal perturbations. The change in width of the junction leads to a renormalization of the magnetic flux in comparison with the case of a linear one-dimensional model. The influence of the model parameters on the stability of the states of the magnetic flux is investigated in detail, particularly that of the shape parameter. The critical curve of the junction is constructed from pieces of the critical curves for the different magnetic flux distributions having the highest critical currents for the given magnetic field.

  4. High-temperature superconductor vertically-stacked Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Yoshinaga, Y; Kito, T; Izawa, S; Maruyama, M; Inoue, M; Fujimaki, A; Hayakawa, H [Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2002-12-01

    We study vertically-stacked interface-treated Josephson junctions (ITJs). The barriers of ITJs are formed by Ar ion etching and subsequent annealing, not by depositing an artificial barrier. We have investigated the dependences of the junction properties on the processing parameters. It is found that the control of junction properties can be realized by controlling the incidence angle of Ar, and that the higher accelerating voltage of Ar reduces leakage paths in a barrier. Moreover, we have successfully eliminated the excess current of the junctions using the PrGaO{sub 3} (PGO) doping process. We conclude that the conjunction of the interface treatment and the PGO doping technique leads to highly integrated Josephson circuits.

  5. High-temperature superconductor vertically-stacked Josephson junctions

    CERN Document Server

    Yoshinaga, Y; Izawa, S; Maruyama, M; Inoue, M; Fujimaki, A; Hayakawa, H

    2002-01-01

    We study vertically-stacked interface-treated Josephson junctions (ITJs). The barriers of ITJs are formed by Ar ion etching and subsequent annealing, not by depositing an artificial barrier. We have investigated the dependences of the junction properties on the processing parameters. It is found that the control of junction properties can be realized by controlling the incidence angle of Ar, and that the higher accelerating voltage of Ar reduces leakage paths in a barrier. Moreover, we have successfully eliminated the excess current of the junctions using the PrGaO sub 3 (PGO) doping process. We conclude that the conjunction of the interface treatment and the PGO doping technique leads to highly integrated Josephson circuits.

  6. Effect of surface losses on soliton propagation in Josephson junctions

    DEFF Research Database (Denmark)

    Davidson, A.; Pedersen, Niels Falsig; Pagano, S.

    1986-01-01

    We have explored numerically the effects on soliton propagation of a third order damping term in the modified sine-Gordon equation. In Josephson tunnel junctions such a term corresponds physically to quasiparticle losses within the metal electrodes of the junction. We find that this loss term pla...... the dominant role in determining the shape and stability of the soliton at high velocity. Applied Physics Letters is copyrighted by The American Institute of Physics.......We have explored numerically the effects on soliton propagation of a third order damping term in the modified sine-Gordon equation. In Josephson tunnel junctions such a term corresponds physically to quasiparticle losses within the metal electrodes of the junction. We find that this loss term plays...

  7. Radiologic staging of esophageal and gastroesophageal junction carcinoma

    NARCIS (Netherlands)

    H. van Overhagen (Hans)

    1993-01-01

    textabstractPretreatment radiologic staging can, theoretically, improve the effectiveness and results of surgical treatment in esophageal and gastroesophageal junction carcinoma. Ideally, on these studies it is possible to select only patients with limited local disease for surgery, whereas those

  8. Fluxon bunching in supercurrent-coupled Josephson junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Lomdahl, Peter S.; Samuelsen, Mogens Rugholm

    1993-01-01

    We investigate analytically and numerically the interaction between fluxons of different Josephson junctions coupled through Cooper-pair tunneling. We find that the supercurrent interaction gives rise to attraction between fluxons regardless of their polarity, although fluxons of different polari...

  9. Magnetoanisotropic Andreev reflection in ferromagnet-superconductor junctions.

    Science.gov (United States)

    Högl, Petra; Matos-Abiague, Alex; Žutić, Igor; Fabian, Jaroslav

    2015-09-11

    Andreev reflection spectroscopy of ferromagnet-superconductor (FS) junctions [corrected] is an important probe of spin polarization. We theoretically investigate spin-polarized transport in FS junctions in the presence of Rashba and Dresselhaus interfacial spin-orbit fields and show that Andreev reflection can be controlled by changing the magnetization orientation. We predict a giant in- and out-of-plane magnetoanisotropy of the junction conductance. If the ferromagnet is highly spin polarized-in the half-metal limit-the magnetoanisotropic Andreev reflection depends universally on the spin-orbit fields only. Our results show that Andreev reflection spectroscopy can be used for sensitive probing of interfacial spin-orbit fields in a FS junction.

  10. Coherent Magnetic Switching in a Permalloy Submicron Junction

    CERN Document Server

    Wang, Junlin; Lu, Xianyang; Zhang, Jason; Ling, Hua; Wu, Jing; Zhou, Yan; Xu, Yongbing

    2016-01-01

    This work provides a numerical micromagnetic study of the magnetic switching of a submicron magnetic junction in a Permalloy (Ni80Fe20) cross structure. The simulation results demonstrate that the magnetic domain at the junction can be controlled to switch coherently by the applied magnetic field. This coherent magnetic switching in the cross structure has been found to be reversible and the 2-bit information can be written in the magnetic junction. For information storage, this kind of device can also realize the function of a quaternary arithmetic unit. By varying the direction of the applied magnetic field, we have demonstrated that this magnetic junction could be the building block for a magnetoresistive random access memory (MRAM) or a quaternary magnetic arithmetic unit.

  11. The gap junction proteome and its relationship to disease.

    Science.gov (United States)

    Laird, Dale W

    2010-02-01

    In recent years our understanding of connexins has advanced from viewing them simply as proteins with a surprisingly short lifespan that form gap junction channels. Connexins are now known to be multifaceted proteins at the core of many multiprotein complexes that link to structural junctional complexes and cytoskeletal elements, and also to the cellular machinery that facilitates their transport, assembly, function and internalization. Collectively, these connexin-binding proteins can be termed the 'gap junction proteome'. The mechanistic understanding of the gap junction proteome with regards to the dynamic life cycle of connexins has grown further in importance in light of the large number of human diseases attributed to connexin gene mutations and regulatory changes in connexin spatial localization and expression levels.

  12. Congenital right sided ureteropelvic junction obstruction in right ...

    African Journals Online (AJOL)

    V. Singh

    Congenital right sided ureteropelvic junction obstruction in right crossed ... Peer review under responsibility of Pan African Urological Surgeons' Asso- ciation. ... There was large gap between the UPJ and the .... relationship to renal disease.

  13. Quantum-confined Stark effect in band-inverted junctions

    Science.gov (United States)

    Díaz-Fernández, A.; Domínguez-Adame, F.

    2017-09-01

    Topological phases of matter are often characterized by interface states, which were already known to occur at the boundary of a band-inverted junction in semiconductor heterostructures. In IV-VI compounds such interface states are properly described by a two-band model, predicting the appearance of a Dirac cone in single junctions. We study the quantum-confined Stark effect of interface states due to an electric field perpendicular to a band-inverted junction. We find a closed expression to obtain the interface dispersion relation at any field strength and show that the Dirac cone widens under an applied bias. Thus, the Fermi velocity can be substantially lowered even at moderate fields, paving the way for tunable band-engineered devices based on band-inverted junctions.

  14. Studies of silicon p-n junction solar cells

    Science.gov (United States)

    Neugroschel, A.; Lindholm, F. A.

    1979-01-01

    To provide theoretical support for investigating different ways to obtain high open-circuit voltages in p-n junction silicon solar cells, an analytical treatment of heavily doped transparent-emitter devices is presented that includes the effects of bandgap narrowing, Fermi-Dirac statistics, a doping concentration gradient, and a finite surface recombination velocity at the emitter surface. Topics covered include: (1) experimental determination of bandgap narrowing in the emitter of silicon p-n junction devices; (2) heavily doped transparent regions in junction solar cells, diodes, and transistors; (3) high-low-emitter solar cell; (4) determination of lifetimes and recombination currents in p-n junction solar cells; (5) MOS and oxide-charged-induced BSF solar cells; and (6) design of high efficiency solar cells for space and terrestrial applications.

  15. Evidence for nonlocal electrodynamics in planar Josephson junctions.

    Science.gov (United States)

    Boris, A A; Rydh, A; Golod, T; Motzkau, H; Klushin, A M; Krasnov, V M

    2013-09-13

    We study the temperature dependence of the critical current modulation I(c)(H) for two types of planar Josephson junctions: a low-Tc Nb/CuNi/Nb and a high-Tc YBa2Cu3O(7-δ) bicrystal grain-boundary junction. At low T both junctions exhibit a conventional behavior, described by the local sine-Gordon equation. However, at elevated T the behavior becomes qualitatively different: the I(c)(H) modulation field ΔH becomes almost T independent and neither ΔH nor the critical field for the penetration of Josephson vortices vanish at Tc. Such an unusual behavior is in good agreement with theoretical predictions for junctions with nonlocal electrodynamics. We extract absolute values of the London penetration depth λ from our data and show that a crossover from local to nonlocal electrodynamics occurs with increasing T when λ(T) becomes larger than the electrode thickness.

  16. Bedrock Geologic Map of the Essex Junction Quadrangle, Vermont

    Data.gov (United States)

    Vermont Center for Geographic Information — Digital data from VG12-3, Gale, M., Kim. J., and Ruksznis, A., 2012, Bedrock Geologic Map of the essex Junction Quadrangle: Vermont Geological Survey Open File...

  17. Memory cell operation based on small Josephson junctions arrays

    Science.gov (United States)

    Braiman, Y.; Nair, N.; Rezac, J.; Imam, N.

    2016-12-01

    In this paper we analyze a cryogenic memory cell circuit based on a small coupled array of Josephson junctions. All the basic memory operations (e.g., write, read, and reset) are implemented on the same circuit and different junctions in the array can in principle be utilized for these operations. The presented memory operation paradigm is fundamentally different from conventional single quantum flux operation logics (SFQ). As an example, we demonstrate memory operation driven by a SFQ pulse employing an inductively coupled array of three Josephson junctions. We have chosen realistic Josephson junction parameters based on state-of-the-art fabrication capabilities and have calculated access times and access energies for basic memory cell operations. We also implemented an optimization procedure based on the simulated annealing algorithm to calculate the optimized and typical values of access times and access energies.

  18. Systematic optimization of quantum junction colloidal quantum dot solar cells

    KAUST Repository

    Liu, Huan

    2012-01-01

    The recently reported quantum junction architecture represents a promising approach to building a rectifying photovoltaic device that employs colloidal quantum dot layers on each side of the p-n junction. Here, we report an optimized quantum junction solar cell that leverages an improved aluminum zinc oxide electrode for a stable contact to the n-side of the quantum junction and silver doping of the p-layer that greatly enhances the photocurrent by expanding the depletion region in the n-side of the device. These improvements result in greater stability and a power conversion efficiency of 6.1 under AM1.5 simulated solar illumination. © 2012 American Institute of Physics.

  19. Formation of bubbles in a multisection flow-focusing junction.

    Science.gov (United States)

    Hashimoto, Michinao; Whitesides, George M

    2010-05-01

    The formation of bubbles in a flow-focusing (FF) junction comprising multiple rectangular sections is described. The simplest junctions comprise two sections (throat and orifice). Systematic investigation of the influence on the formation of bubbles of the flow of liquid and the geometry of the junction identifies regimes that generate monodisperse, bidisperse, and tridisperse trains of bubbles. The mechanisms by which these junctions form monodisperse and bidisperse bubbles are inferred from the shapes of the gas thread during breakup: these mechanisms differ primarily by the process in which the gas thread collapses in the throat and/or orifice. The dynamic self-assembly of bidisperse bubbles leads to unexpected groupings of bubbles during their flow along the outlet channel.

  20. Niobium nitride technology for Josephson junction devices

    Energy Technology Data Exchange (ETDEWEB)

    Meckbach, Johannes Maximilian; Merker, Michael; Il' in, Konstantin; Siegel, Michael [Institut fuer Mikro- und Nanoelektronische Systeme (IMS), Karlsruher Institut fuer Technologie (KIT), Hertzstrasse 16, 76187 Karlsruhe (Germany); Haeffelin, Andreas [Institut fuer Werkstoffe der Elektrotechnik (IWE), Karlsruher Institut fuer Technologie(KIT), Adenauerring 20b, 76131 Karlsruhe (Germany)

    2013-07-01

    Over the last decades Nb/Al-AlO{sub x}/Nb multi-layers have been the primary choice for Josephson junction (JJ) devices such as SIS mixers, SQUIDs and RSFQ. Various applications require high critical-current densities j{sub c} and low sub-gap leakage. Additionally, a large gap-voltage benefits the performance of most devices. Nb/Al-AlO{sub x}/Nb technology is limited in j{sub c} due to an increasing transparency of the barrier with increasing j{sub c}, and the energy-gap of the Nb electrodes poses an upper frequency limit for SIS mixers. NbN/AlN/NbN multi-layer technology has emerged as an alternative to Nb/Al-AlO{sub x}/Nb. The upper frequency limit of NbN-based SIS mixing element significantly exceeds that of Nb, and AlN-barriers result in higher j{sub c}'s at identical thicknesses as compared to AlO{sub x}. We have developed an in-situ fabrication technology for NbN/AlN/NbN multi-layers. We found a clear influence of the sputter parameters on the surface morphology of the NbN electrodes, which directly impacts on the quality of the JJs. Transport properties of JJs on different substrates are presented.

  1. Seebeck effect in magnetic tunnel junctions.

    Science.gov (United States)

    Walter, Marvin; Walowski, Jakob; Zbarsky, Vladyslav; Münzenberg, Markus; Schäfers, Markus; Ebke, Daniel; Reiss, Günter; Thomas, Andy; Peretzki, Patrick; Seibt, Michael; Moodera, Jagadeesh S; Czerner, Michael; Bachmann, Michael; Heiliger, Christian

    2011-10-01

    Creating temperature gradients in magnetic nanostructures has resulted in a new research direction, that is, the combination of magneto- and thermoelectric effects. Here, we demonstrate the observation of one important effect of this class: the magneto-Seebeck effect. It is observed when a magnetic configuration changes the charge-based Seebeck coefficient. In particular, the Seebeck coefficient changes during the transition from a parallel to an antiparallel magnetic configuration in a tunnel junction. In this respect, it is the analogue to the tunnelling magnetoresistance. The Seebeck coefficients in parallel and antiparallel configurations are of the order of the voltages known from the charge-Seebeck effect. The size and sign of the effect can be controlled by the composition of the electrodes' atomic layers adjacent to the barrier and the temperature. The geometric centre of the electronic density of states relative to the Fermi level determines the size of the Seebeck effect. Experimentally, we realized 8.8% magneto-Seebeck effect, which results from a voltage change of about -8.7 μV K⁻¹ from the antiparallel to the parallel direction close to the predicted value of -12.1 μV K⁻¹. In contrast to the spin-Seebeck effect, it can be measured as a voltage change directly without conversion of a spin current.

  2. Revisiting the Darmois and Lichnerowicz junction conditions

    Science.gov (United States)

    Lake, Kayll

    2017-10-01

    What have become known as the "Darmois" and "Lichnerowicz" junction conditions are often stated to be equivalent, "essentially" equivalent, in a "sense" equivalent, and so on. One even sees not infrequent reference to the "Darmois-Lichnerowicz" conditions. Whereas the equivalence of these conditions is manifest in Gaussian-normal coordinates, a fact that has been known for close to a century, this equivalence does not extend to a loose definition of "admissible" coordinates (coordinates in which the metric and its first order derivatives are continuous). We show this here by way of a simple, but physically relevant, example. In general, a loose definition of the "Lichnerowicz" conditions gives additional restrictions, some of which simply amount to a convenient choice of gauge, and some of which amount to real physical restrictions, away from strict "admissible" coordinates. The situation was totally confused by a very influential, and now frequently misquoted, paper by Bonnor and Vickers, that erroneously claimed a proof of the equivalence of the "Darmois" and "Lichnerowicz" conditions within this loose definition of "admissible" coordinates. A correct proof, based on a strict definition of "admissible" coordinates, was given years previous by Israel. It is that proof, generally unrecognized, that we must refer to. Attention here is given to a clarification of the subject, and to the history of the subject, which, it turns out, is rather fascinating in itself.

  3. Gamma Radiation Tolerance of Magnetic Tunnel Junctions

    Science.gov (United States)

    Ren, Fanghui; Jander, Albrecht; Dhagat, Pallavi; Nordman, Cathy

    2011-10-01

    Determining the radiation tolerance of magnetic tunnel junctions (MTJ), which are the storage elements of non-volatile magnetoresistive random access memories (MRAM), is important for investigating their potential application in space. In this effort, the effect of gamma radiation on MTJs with MgO tunnel barriers was studied. Experimental and control groups of samples were characterized by ex situ measurements of the magnetoresistive hysteresis loops and I-V curves. The experimental group was exposed to gamma rays from a ^60Co source. The samples initially received a dose of 5.9 Mrad (Si) after which they were again characterized electrically and magnetically. Irradiation was then continued for a cumulative dose of 10 Mrad and the devices re-measured. The result shows no change in magnetic properties such as coercivity or exchange coupling due to irradiation. After correcting for differences in temperature at the time of testing, the tunneling magnetoresistance was also found to be unchanged. Thus, it has been determined that MgO-based MTJs are highly tolerant of gamma radiation, particularly in comparison to silicon field-effect transistors which have been shown to degrade with gamma ray exposure even as low as 100 Krad [Zhiyuan Hu. et al., IEEE trans. on Nucl. Sci., vol. 58, 2011].

  4. Photoinduced carrier annihilation in silicon pn junction

    Science.gov (United States)

    Sameshima, Toshiyuki; Motoki, Takayuki; Yasuda, Keisuke; Nakamura, Tomohiko; Hasumi, Masahiko; Mizuno, Toshihisa

    2015-08-01

    We report analysis of the photo-induced minority carrier effective lifetime (τeff) in a p+n junction formed on the top surfaces of a n-type silicon substrate by ion implantation of boron and phosphorus atoms at the top and bottom surfaces followed by activation by microwave heating. Bias voltages were applied to the p+ boron-doped surface with n+ phosphorus-doped surface kept at 0 V. The values of τeff were lower than 1 × 10-5 s under the reverse-bias condition. On the other hand, τeff markedly increased to 1.4 × 10-4 s as the forward-bias voltage increased to 0.7 V and then it leveled off when continuous-wave 635 nm light was illuminated at 0.74 mW/cm2 on the p+ surface. The carrier annihilation velocity S\\text{p + } at the p+ surface region was numerically estimated from the experimental τeff. S\\text{p + } ranged from 4000 to 7200 cm/s under the reverse-bias condition when the carrier annihilation velocity S\\text{n + } at the n+ surface region was assumed to be a constant value of 100 cm/s. S\\text{p + } markedly decreased to 265 cm/s as the forward-bias voltage increased to 0.7 V.

  5. Spin-crossover molecule based thermoelectric junction

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Dibyajyoti [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); Parida, Prakash [Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg (Germany); Pati, Swapan K. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2015-05-11

    Using ab-initio numerical methods, we explore the spin-dependent transport and thermoelectric properties of a spin-crossover molecule (i.e., iron complex of 2-(1H-pyrazol-1-yl)-6-(1H-tetrazole-5-yl)pyridine) based nano-junction. We demonstrate a large magnetoresistance, efficient conductance-switching, and spin-filter activity in this molecule-based two-terminal device. The spin-crossover process also modulates the thermoelectric entities. It can efficiently switch the magnitude as well as spin-polarization of the thermocurrent. We find that thermocurrent is changed by ∼4 orders of magnitude upon spin-crossover. Moreover, it also substantially affects the thermopower and consequently, the device shows extremely efficient spin-crossover magnetothermopower generation. Furthermore, by tuning the chemical potential of electrodes into a certain range, a pure spin-thermopower can be achieved for the high-spin state. Finally, the reasonably large values of figure-of-merit in the presence and absence of phonon demonstrate a large heat-to-voltage conversion efficiency of the device. We believe that our study will pave an alternative way of tuning the transport and thermoelectric properties through the spin-crossover process and can have potential applications in generation of spin-dependent current, information storage, and processing.

  6. Parallel Quantum Circuit in a Tunnel Junction

    Science.gov (United States)

    Faizy Namarvar, Omid; Dridi, Ghassen; Joachim, Christian

    2016-07-01

    Spectral analysis of 1 and 2-states per line quantum bus are normally sufficient to determine the effective Vab(N) electronic coupling between the emitter and receiver states through the bus as a function of the number N of parallel lines. When Vab(N) is difficult to determine, an Heisenberg-Rabi time dependent quantum exchange process must be triggered through the bus to capture the secular oscillation frequency Ωab(N) between those states. Two different linear and regimes are demonstrated for Ωab(N) as a function of N. When the initial preparation is replaced by coupling of the quantum bus to semi-infinite electrodes, the resulting quantum transduction process is not faithfully following the Ωab(N) variations. Because of the electronic transparency normalisation to unity and of the low pass filter character of this transduction, large Ωab(N) cannot be captured by the tunnel junction. The broadly used concept of electrical contact between a metallic nanopad and a molecular device must be better described as a quantum transduction process. At small coupling and when N is small enough not to compensate for this small coupling, an N2 power law is preserved for Ωab(N) and for Vab(N).

  7. Parallel Quantum Circuit in a Tunnel Junction.

    Science.gov (United States)

    Faizy Namarvar, Omid; Dridi, Ghassen; Joachim, Christian

    2016-07-25

    Spectral analysis of 1 and 2-states per line quantum bus are normally sufficient to determine the effective Vab(N) electronic coupling between the emitter and receiver states through the bus as a function of the number N of parallel lines. When Vab(N) is difficult to determine, an Heisenberg-Rabi time dependent quantum exchange process must be triggered through the bus to capture the secular oscillation frequency Ωab(N) between those states. Two different linear and regimes are demonstrated for Ωab(N) as a function of N. When the initial preparation is replaced by coupling of the quantum bus to semi-infinite electrodes, the resulting quantum transduction process is not faithfully following the Ωab(N) variations. Because of the electronic transparency normalisation to unity and of the low pass filter character of this transduction, large Ωab(N) cannot be captured by the tunnel junction. The broadly used concept of electrical contact between a metallic nanopad and a molecular device must be better described as a quantum transduction process. At small coupling and when N is small enough not to compensate for this small coupling, an N(2) power law is preserved for Ωab(N) and for Vab(N).

  8. Quantum statistical theory of semiconductor junctions in thermal equilibrium

    Science.gov (United States)

    Von Roos, O.

    1977-01-01

    Free carrier and electric field distributions of one-dimensional semiconductor junctions are evaluated using a quantum mechanical phase-space distribution and its corresponding Boltzmann equation. Attention is given to quantum and exchange corrections in cases of high doping concentrations when carrier densities become degenerate. Quantitative differences between degenerate and classical junction characteristics, e.g., maximum electric field and built-in voltage and carrier concentration within the transition region, are evaluated numerically.

  9. Raman Scattering at Plasmonic Junctions Shorted by Conductive Molecular Bridges

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Hu, Dehong; Apkarian, V. Ara; Hess, Wayne P.

    2013-04-10

    Intensity spikes in Raman scattering, accompanied by switching between line spectra and band spectra, can be assigned to shorting the junction plasmon through molecular conductive bridges. This is demonstrated through Raman trajectories recorded at a plasmonic junction formed by a gold AFM tip in contact with a silver surface coated either with biphenyl-4,4’-dithiol or biphenyl-4-thiol. The fluctuations are absent in the monothiol. In effect, the making and breaking of chemical bonds is tracked.

  10. Craniovertebral junction stenosis in Lenz-Majewski syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Mizuguchi, Koichi; Ishigro, Akira [National Center for Child Health and Development, Department of General Pediatrics and Interdisciplinary Medicine, Setagaya-ku, Tokyo (Japan); Miyazaki, Osamu [National Center for Child Health and Development, Department of Radiology, Tokyo (Japan); Nishimura, Gen [Tokyo Metropolitan Children' s Medical Center, Department of Pediatric Imaging, Tokyo (Japan)

    2015-09-15

    We report a girl with Lenz-Majewski syndrome associated with craniovertebral junction stenosis that led to communicating hydrocephalus and cervical myelopathy. The life-threatening complication was related to progressive craniovertebral hyperostosis that rapidly exacerbated during early childhood. Despite initial success of surgical intervention at 2 years of age, she developed apneic spells and died suddenly at age 5 years. Close monitoring for craniovertebral junction stenosis is essential to reduce morbidity and mortality in children with Lenz-Majewski syndrome. (orig.)

  11. Paracellular drug absorption enhancement through tight junction modulation

    OpenAIRE

    Lemmer, Hendrik Jacobus Righard; Josias H. Hamman

    2013-01-01

    Introduction: Inclusion of absorption-enhancing agents in dosage forms is one approach to improve the bioavailability of active pharmaceutical ingredients with low membrane permeability. Tight junctions are dynamic protein structures that form a regulated barrier for movement of molecules through the intercellular spaces across the intestinal epithelium. Some drug absorption enhancers are capable of loosening tight junctions and thereby facilitate paracellular absorption of drug molecules. ...

  12. Resonance features of coupled Josephson junctions: radiation and shunting

    Science.gov (United States)

    Shukrinov, Yu M.; Seidel, P.; Il'ichev, E.; Nawrocki, W.; Grajcar, M.; Plecenik, P. A.; Rahmonov, I. R.; Kulikov, K.

    2012-11-01

    We study the phase dynamics and the resonance features of coupled Josephson junctions in layered superconductors and their manifestations in the current- voltage characteristics and temporal dependence of the electric charge in the superconducting layers. Results on the effect of the external radiation and shunting of the stack of Josephson junctions by LC-elements are presented. We discuss the ideas concerning the experimental observation of these resonances.

  13. High Density Planar High Temperature Superconducting Josephson Junctions Arrays

    Science.gov (United States)

    2006-09-01

    TIT,) 3 dependance . At lower temperatures it follows a (1 - T/T,)2 depen- dance ........ ................................... 57 4.7 Shapiro steps in...70 4.23 Dependance of the critical current for a ten junction array on mi- crowave power ..................................... 71 4.24 Resistance vs...GHz microwave radiation. (b) Microwave power dependance of the critical current and 1st-order Shapiro step. 76 5.2 (a) Single junction critical current

  14. Recognition of Nucleic Acid Junctions Using Triptycene-Based Molecules

    OpenAIRE

    Barros, Stephanie A.; Chenoweth, David M.

    2014-01-01

    Nucleic acid modulation by small molecules is an essential process across the kingdoms of life. Targeting nucleic acids with small molecules represents a significant challenge at the forefront of chemical biology. Nucleic acid junctions are ubiquitous structural motifs in nature and in designed materials. Herein, we describe a new class of structure specific nucleic acid junction stabilizers based on a triptycene scaffold. Triptycenes provide significant stabilization of DNA and RNA three-way...

  15. Craniovertebral junction stenosis in Lenz-Majewski syndrome.

    Science.gov (United States)

    Mizuguchi, Koichi; Miyazaki, Osamu; Nishimura, Gen; Ishigro, Akira

    2015-09-01

    We report a girl with Lenz-Majewski syndrome associated with craniovertebral junction stenosis that led to communicating hydrocephalus and cervical myelopathy. The life-threatening complication was related to progressive craniovertebral hyperostosis that rapidly exacerbated during early childhood. Despite initial success of surgical intervention at 2 years of age, she developed apneic spells and died suddenly at age 5 years. Close monitoring for craniovertebral junction stenosis is essential to reduce morbidity and mortality in children with Lenz-Majewski syndrome.

  16. A rare presentation of lipoma on mandibular mucogingival junction

    Science.gov (United States)

    Sharma, Gaurav; Jain, Kanu; Nagpal, Archna; Baiju, Chandrababu Sudha

    2016-01-01

    Lipoma is the most common tumor of mesenchymal tissues of body, but its occurrence in oral cavity is infrequent. Buccal mucosa is the most common intraoral site of lipoma followed by tongue, floor of the mouth, and buccal vestibule. The involvement of mucogingival junction is rare. We present a unique case report of oral lipoma occurring on mandibular mucogingival junction with review of literature which has emphasis on differential diagnosis. PMID:27143835

  17. Development of Junction Elements from Study of the Bionics

    Institute of Scientific and Technical Information of China (English)

    Wilson Kindlein Junior; Luis Henrique Alves C(a)ndido; André Canal Marques; Sandra Souza dos Santos; Maurício da Silva Viegas

    2007-01-01

    The applications of bionic methodology developed by the Laboratory of Design and Material Selection as basis in the creation of junction elements were demonstrated.These elements favor the application of Ecodesign in reference to the effectiveness of product dismount aiming the reduction of ambient impact in all its phases of use.The creation,the development and the confection of new junction elements were described,and case studies of new products developed specificallv with this purpose were presented.

  18. Resonator coupled Josephson junctions; parametric excitations and mutual locking

    DEFF Research Database (Denmark)

    Jensen, H. Dalsgaard; Larsen, A.; Mygind, Jesper

    1991-01-01

    Self-pumped parametric excitations and mutual locking in systems of Josephson tunnel junctions coupled to multimode resonators are reported. For the very large values of the coupling parameter, obtained with small Nb-Al2O3-Nb junctions integrated in superconducting microstrip resonators, the DC I......-V characteristic shows an equidistant series of current steps generated by subharmonic pumping of the fundamental resonator mode. This is confirmed by measurement of frequency and linewidth of the emitted Josephson radiation...

  19. Evidence for a minigap in YBCO grain boundary Josephson junctions.

    Science.gov (United States)

    Lucignano, P; Stornaiuolo, D; Tafuri, F; Altshuler, B L; Tagliacozzo, A

    2010-10-01

    Self-assembled YBaCuO diffusive grain boundary submicron Josephson junctions offer a realization of a special regime of the proximity effect, where normal state coherence prevails on the superconducting coherence in the barrier region. Resistance oscillations from the current-voltage characteristic encode mesoscopic information on the junction and more specifically on the minigap induced in the barrier. Their persistence at large voltages is evidence of the long lifetime of the antinodal (high energy) quasiparticles.

  20. Reinventing the PN Junction: Dimensionality Effects on Tunneling Switches

    Science.gov (United States)

    2012-05-11

    lower paraboloid represents all of the available states in k-space on the left side of the junction and the upper paraboloid represents the available...and so the paraboloids must overlap. However, as seen in the right part of the figure, they can only overlap at a single energy. Furthermore, the... paraboloids on each side of the junction only intersect at a single energy. 62 need to sum Eqn. (6.8.3) over all initial states or final