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Sample records for adherens junctions caused

  1. Negatively charged silver nanoparticles cause retinal vascular permeability by activating plasma contact system and disrupting adherens junction.

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    Long, Yan-Min; Zhao, Xing-Chen; Clermont, Allen C; Zhou, Qun-Fang; Liu, Qian; Feener, Edward P; Yan, Bing; Jiang, Gui-Bin

    2016-01-01

    Silver nanoparticles (AgNPs) have been extensively used as antibacterial component in numerous healthcare, biomedical and consumer products. Therefore, their adverse effects to biological systems have become a major concern. AgNPs have been shown to be absorbed into circulation and redistributed into various organs. It is thus of great importance to understand how these nanoparticles affect vascular permeability and uncover the underlying molecular mechanisms. A negatively charged mecaptoundeonic acid-capped silver nanoparticle (MUA@AgNP) was investigated in this work. Ex vivo experiments in mouse plasma revealed that MUA@AgNPs caused plasma prekallikrein cleavage, while positively charged or neutral AgNPs, as well as Ag ions had no effect. In vitro tests revealed that MUA@AgNPs activated the plasma kallikrein-kinin system (KKS) by triggering Hageman factor autoactivation. By using specific inhibitors aprotinin and HOE 140, we demonstrated that KKS activation caused the release of bradykinin, which activated B2 receptors and induced the shedding of adherens junction protein, VE-cadherin. These biological perturbations eventually resulted in endothelial paracellular permeability in mouse retina after intravitreal injection of MUA@AgNPs. The findings from this work provided key insights for toxicity modulation and biomedical applications of AgNPs. PMID:26399585

  2. 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.

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

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    Yamamoto, Hideaki; Maruo, Tomohiko; Majima, Takashi; Ishizaki, Hiroyoshi; Tanaka-Okamoto, Miki; Miyoshi, Jun; Mandai, Kenji; Takai, Yoshimi

    2013-01-01

    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. PMID:24236178

  4. Adherens junction function and regulation during zebrafish gastrulation

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    Schepis, Antonino; Nelson, W. James

    2012-01-01

    The adherens junction (AJ) comprises multi-protein complexes required for cell-cell adhesion in embryonic development and adult tissue homeostasis. Mutations in key proteins and mis-regulation of AJ adhesive properties can lead to pathologies such as cancer. In recent years, the zebrafish has become an excellent model organism to integrate cell biology in the context of a multicellular organization. The combination of classical genetic approaches with new tools for live imaging and biophysica...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Negative pressure induces p120-catenin-dependent adherens junction disassembly in keratinocytes during wound healing.

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    Huang, Ching-Hui; Hsu, Chih-Chin; Chen, Carl Pai-Chu; Chow, Shu-Er; Wang, Jong-Shyan; Shyu, Yu-Chiau; Lu, Mu-Jie

    2016-09-01

    A negative-pressure of 125mmHg (NP) has been widely used to treat chronic wounds in modern medicine. Keratinocytes under NP treatment have shown accelerated cell movement and decreased E-cadherin expression. However, the molecular mechanism of E-cadherin regulation under NP remains incompletely understood. Therefore, we investigated the E-cadherin regulation in keratinocytes (HaCaT cells) under NP. HaCaT cells were treated at ambient pressure (AP) and NP for 12h. Cell movement was measured by traditional and electric wound healing assays at the 2 different pressures. Mutants with overexpression of p120-catenin (p120(ctn)) were used to observe the effect of NP on p120(ctn) and E-cadherin expression during wound healing. Cell fractionation and immunoblotting data showed that NP increased Y228-phosphorylated p120(ctn) level and resulted in the translocation of p120(ctn) from the plasma membrane to cytoplasm. Immunofluorescence images revealed that NP decreased the co-localization of p120(ctn) and E-cadherin on the plasma membrane. Knockdown of p120(ctn) reduced E-cadherin expression and accelerated cell movement under AP. Overexpression of the Y228-phosphorylation-mimic p120(ctn) decreased E-cadherin membrane expression under both AP and NP. Phosphorylation-deficient mutants conferred restored adherens junctions (AJs) under NP. The Src inhibitor blocked the phosphorylation of p120(ctn) and impeded cell migration under NP. In conclusion, Src-dependent phosphorylation of p120(ctn) can respond rapidly to NP and contribute to E-cadherin downregulation. The NP-induced disassembly of the AJ further accelerates wound healing. PMID:27220534

  13. The F-BAR protein pacsin2 inhibits asymmetric VE-cadherin internalization from tensile adherens junctions.

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    Dorland, Yvonne L; Malinova, Tsveta S; van Stalborch, Anne-Marieke D; Grieve, Adam G; van Geemen, Daphne; Jansen, Nicolette S; de Kreuk, Bart-Jan; Nawaz, Kalim; Kole, Jeroen; Geerts, Dirk; Musters, René J P; de Rooij, Johan; Hordijk, Peter L; Huveneers, Stephan

    2016-01-01

    Vascular homoeostasis, development and disease critically depend on the regulation of endothelial cell-cell junctions. Here we uncover a new role for the F-BAR protein pacsin2 in the control of VE-cadherin-based endothelial adhesion. Pacsin2 concentrates at focal adherens junctions (FAJs) that are experiencing unbalanced actomyosin-based pulling. FAJs move in response to differences in local cytoskeletal geometry and pacsin2 is recruited consistently to the trailing end of fast-moving FAJs via a mechanism that requires an intact F-BAR domain. Photoconversion, photobleaching, immunofluorescence and super-resolution microscopy reveal polarized dynamics, and organization of junctional proteins between the front of FAJs and their trailing ends. Interestingly, pacsin2 recruitment inhibits internalization of the VE-cadherin complex from FAJ trailing ends and is important for endothelial monolayer integrity. Together, these findings reveal a novel junction protective mechanism during polarized trafficking of VE-cadherin, which supports barrier maintenance within dynamic endothelial tissue. PMID:27417273

  14. 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

  15. Microtubule plus-end and minus-end capture at adherens junctions is involved in the assembly of apico-basal arrays in polarised epithelial cells.

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    Bellett, Gemma; Carter, Jane M; Keynton, Jennifer; Goldspink, Deborah; James, Colin; Moss, David K; Mogensen, Mette M

    2009-10-01

    Apico-basal polarisation of epithelial cells involves a dramatic reorganisation of the microtubule cytoskeleton. The classic radial array of microtubules focused on a centrally located centrosome typical of many animal cells is lost or greatly reduced and a non-centrosomal apico-basal array develops. The molecules and mechanisms responsible for the assembly and positioning of these non-centrosomal microtubules have not been fully elucidated. Using a Nocodazole induced regrowth assay in invitro culture (MDCK) and in situ epithelial (cochlear Kolliker's) cell models we establish that the apico-basal array originates from the centrosome and that the non-centrosomal microtubule minus-end anchoring sites do not contribute significantly to their nucleation. Confocal and electron microscopy revealed that an extended radial array assembles with microtubule plus-ends targeting cadheren sites at adherens junctions and EB1 and CLIP-170 co-localising with beta-catenin and dynein clusters at the junction sites. The extended radial array is likely to be a vital intermediate step in the assembly process with cortical anchored dynein providing the mechanical force required for microtubule release, translocation and capture. Ultrastructural analyses of the apico-basal arrays in fully polarised MDCK and Kolliker's cells revealed microtubule minus-end association with the most apical adherens junction (Zonula adherens). We propose that a release and capture model involving both microtubule plus- and minus-end capture at adherens junctions is responsible for the generation of non-centrosomal apico-basal arrays in most centrosome containing polarised epithelial cells. PMID:19479825

  16. Transient receptor potential channel 1 maintains adherens junction plasticity by suppressing sphingosine kinase 1 expression to induce endothelial hyperpermeability.

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    Tauseef, Mohammad; Farazuddin, Mohammad; Sukriti, Sukriti; Rajput, Charu; Meyer, James Otto; Ramasamy, Suresh Kumar; Mehta, Dolly

    2016-01-01

    Stability of endothelial cell (EC) adherens junctions (AJs) is central for prevention of tissue edema, the hallmark of chronic inflammatory diseases including acute respiratory distress syndrome. Here, we demonstrate a previously unsuspected role of sphingosine kinase 1 (SPHK1) in the mechanism by which transient receptor potential channel 1 (Trpc1)-mediated Ca(2+) entry destabilizes AJs. Trpc1(-/-) monolayers showed a 2.2-fold increase in vascular endothelial (VE)-cadherin cell-surface expression above wild-type (WT) monolayers. Thrombin increased endothelial permeability (evident by a 5-fold increase in interendothelial gap area and 60% decrease in transendothelial electrical resistance) in WT but not Trpc1(-/-) ECs. Trpc1(-/-) mice resisted the hyperpermeability effects of the edemagenic agonists used and exhibited 60% less endotoxin-induced mortality. Because sphingosine-1-phosphate (S1P) strengthens AJs, we determined if TRPC1 functioned by inhibiting SPHK1 activity, which generates S1P. Intriguingly, Trpc1(-/-) ECs or ECs transducing a TRPC1-inactive mutant showed a 1.5-fold increase in basal SPHK1 expression compared with WT ECs, resulting in a 2-fold higher S1P level. SPHK1 inhibitor SK1-I decreased basal transendothelial electrical resistance more in WT ECs (48 and 72% reduction at 20 and 50 μM, respectively) than in Trpc1(-/-) ECs. However, SK1-I pretreatment rescued thrombin-induced EC permeability in Trpc1(-/-) ECs. Thus, TRPC1 suppression of basal SPHK1 activity enables EC-barrier destabilization by edemagenic agonists. PMID:26316271

  17. Striatins as plaque molecules of zonulae adhaerentes in simple epithelia, of tessellate junctions in stratified epithelia, of cardiac composite junctions and of various size classes of lateral adherens junctions in cultures of epithelia- and carcinoma-derived cells.

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    Franke, Werner W; Rickelt, Steffen; Zimbelmann, Ralf; Dörflinger, Yvette; Kuhn, Caecilia; Frey, Norbert; Heid, Hans; Rosin-Arbesfeld, Rina

    2015-03-01

    Proteins of the striatin family (striatins 1-4; sizes ranging from 90 to 110 kDa on SDS-polyacrylamide gel electrophoresis) are highly homologous in their amino acid sequences but can differ in their cell-type-specific gene expression patterns and biological functions. In various cell types, we have found one, two or three polypeptides of this evolutionarily old and nearly ubiquitous family of proteins known to serve as scaffold proteins for diverse protein complexes. Light and electron microscopic immunolocalization methods have revealed striatins in mammalian cell-cell adherens junctions (AJs). In simple epithelia, we have localized striatins as constitutive components of the plaques of the subapical zonulae adhaerentes of cells, including intestinal, glandular, ductal and urothelial cells and hepatocytes. Striatins colocalize with E-cadherin or E-N-cadherin heterodimers and with the plaque proteins α- and β-catenin, p120 and p0071. In some epithelia and carcinomas and in cultured cells derived therefrom, striatins are also seen in lateral AJs. In stratified epithelia and in corresponding squamous cell carcinomas, striatins can be found in plaques of some forms of tessellate junctions. Moreover, striatins are major plaque proteins of composite junctions (CJs; areae compositae) in the intercalated disks connecting cardiomyocytes, colocalizing with other CJ molecules, including plectin and ankyrin-G. We discuss the "multimodulator" scaffold roles of striatins in the initiation and regulation of the formation of various complex particles and structures. We propose that striatins are included in the diagnostic candidate list of proteins that, in the CJs of human hearts, can occur in mutated forms in the pathogeneses of hereditary cardiomyopathies, as seen in some types of genetically determined heart damage in boxer dogs. PMID:25501894

  18. 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.

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    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.

  19. Protective role of p120-catenin in maintaining the integrity of adherens and tight junctions in ventilator-induced lung injury

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    Gu, Changping; LIU, MENGJIE; Zhao, Tao; Wang, Dong; Wang, Yuelan

    2015-01-01

    Background Ventilator-induced lung injury (VILI) is one of the most common complications for patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Although p120 is an important protein in the regulation of cell junctions, further mechanisms should be explored for prevention and treatment of VILI. Methods Mouse lung epithelial cells (MLE-12), which were transfected with p120 small interfering (si)RNA, p120 cDNA, wild-type E-cadherin juxtamembrane domain or a K83R...

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

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    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

  1. Syncope caused by congenital anomaly at the craniovertebral junction: a case report

    OpenAIRE

    Miyakoshi, Naohisa; Hongo, Michio; Kasukawa, Yuji; Shimada, Yoichi

    2014-01-01

    Introduction Anomalies in the craniovertebral junction may be a rare cause of syncope. The mechanisms of syncope related to craniovertebral junction anomaly remain unknown. We present an extremely rare case with anomaly in the craniovertebral junction and syncope, and discuss the mechanism of the syncope. Case presentation A 10-year-old Japanese boy with a congenital anomaly in the craniovertebral junction presented with recurrent syncope. A physical examination showed generalized hyperreflex...

  2. 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.

  3. 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.

  4. 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. PMID:26365579

  5. 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.

  6. Calcium-Ask1-MKK7-JNK2-c-Src Signaling Cascade Mediates Disruption of Intestinal Epithelial Tight Junctions by Dextran Sulfate Sodium

    Science.gov (United States)

    Samak, Geetha; Chaudhry, Kamaljit K.; Gangwar, Ruchika; Narayanan, Damodaran; Jaggar, Jonathan H.; Rao, RadhaKrishna

    2015-01-01

    Disruption of intestinal epithelial tight junctions is an important event in the pathogenesis of ulcerative colitis. Dextran sodium sulfate (DSS) induces colitis in mice with the symptoms similar to ulcerative colitis. However, the mechanism of DSS-induced colitis is unknown. We investigated the mechanism of DSS-induced disruption of intestinal epithelial tight junctions and barrier dysfunction in Caco-2 cell monolayers in vitro and mouse colon in vivo. DSS treatment resulted in disruption of tight junctions, adherens junctions and actin cytoskeleton leading to barrier dysfunction in Caco-2 cell monolayers. DSS induced a rapid activation of c-jun N-terminal kinase (JNK), and the inhibition or knockdown of JNK2 attenuated DSS-induced tight junction disruption and barrier dysfunction. In mice, DSS administration for 4 days caused redistribution of tight junction and adherens junction proteins from the epithelial junctions, which was blocked by JNK inhibitor. In Caco-2 cell monolayers, DSS increased intracellular Ca2+ concentration, and depletion of intracellular Ca2+ by BAPTA or thapsigargin attenuated DSS-induced JNK activation, tight junction disruption and barrier dysfunction. Knockdown of Ask1 or MKK7 blocked DSS-induced tight junction disruption and barrier dysfunction. DSS activated c-Src by a Ca2+ and JNK-dependent mechanism. Inhibition of Src kinase activity or knockdown of c-Src blocked DSS-induced tight junction disruption and barrier dysfunction. DSS increased Tyr-phosphorylation of occludin, ZO-1, E-cadherin and β-catenin. SP600125 abrogated DSS-induced Tyr-phosphorylation of junctional proteins. Recombinant JNK2 induced threonine phosphorylation and auto phosphorylation of c-Src. This study demonstrates that Ca2+-Ask1-MKK7-JNK2-cSrc signaling cascade mediates DSS-induced tight junction disruption and barrier dysfunction. PMID:25377781

  7. 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.

  8. Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly.

    Science.gov (United States)

    Mao, Hanqian; McMahon, John J; Tsai, Yi-Hsuan; Wang, Zefeng; Silver, Debra L

    2016-09-01

    The exon junction complex (EJC) is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling. Using a new conditional allele, we first show that Eif4a3 haploinsufficiency phenocopies aberrant neurogenesis and microcephaly of Magoh and Rbm8a mutant mice. Transcriptomic and proteomic analyses of embryonic brains at the onset of neurogenesis identifies common pathways altered in each of the 3 EJC mutants, including ribosome, proteasome, and p53 signaling components. We further demonstrate all 3 mutants exhibit defective splicing of RNA regulatory proteins, implying an EJC dependent RNA regulatory network that fine-tunes gene expression. Finally, we show that genetic ablation of one downstream pathway, p53, significantly rescues microcephaly of all 3 EJC mutants. This implicates p53 activation as a major node of neurodevelopmental pathogenesis following EJC impairment. Altogether our study reveals new mechanisms to help explain how EJC mutations influence neurogenesis and underlie neurodevelopmental disease. PMID:27618312

  9. 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.

  10. Destruction of the hepatocyte junction by intercellular invasion of Leptospira causes jaundice in a hamster model of Weil's disease.

    Science.gov (United States)

    Miyahara, Satoshi; Saito, Mitsumasa; Kanemaru, Takaaki; Villanueva, Sharon Y A M; Gloriani, Nina G; Yoshida, Shin-ichi

    2014-08-01

    Weil's disease, the most severe form of leptospirosis, is characterized by jaundice, haemorrhage and renal failure. The mechanisms of jaundice caused by pathogenic Leptospira remain unclear. We therefore aimed to elucidate the mechanisms by integrating histopathological changes with serum biochemical abnormalities during the development of jaundice in a hamster model of Weil's disease. In this work, we obtained three-dimensional images of infected hamster livers using scanning electron microscope together with freeze-cracking and cross-cutting methods for sample preparation. The images displayed the corkscrew-shaped bacteria, which infiltrated the Disse's space, migrated between hepatocytes, detached the intercellular junctions and disrupted the bile canaliculi. Destruction of bile canaliculi coincided with the elevation of conjugated bilirubin, aspartate transaminase and alkaline phosphatase levels in serum, whereas serum alanine transaminase and γ-glutamyl transpeptidase levels increased slightly, but not significantly. We also found in ex vivo experiments that pathogenic, but not non-pathogenic leptospires, tend to adhere to the perijunctional region of hepatocyte couplets isolated from hamsters and initiate invasion of the intercellular junction within 1 h after co-incubation. Our results suggest that pathogenic leptospires invade the intercellular junctions of host hepatocytes, and this invasion contributes in the disruption of the junction. Subsequently, bile leaks from bile canaliculi and jaundice occurs immediately. Our findings revealed not only a novel pathogenicity of leptospires, but also a novel mechanism of jaundice induced by bacterial infection. PMID:24945433

  11. Vinculin associates with endothelial VE-cadherin junctions to control force-dependent remodeling

    NARCIS (Netherlands)

    Huveneers, S.; Oldenburg, J.; Spanjaard, E.; Van Der Krogt, G.; Grigoriev, I.; Akhmanova, A.; Rehmann, H.; de Rooij, J.

    2012-01-01

    To remodel endothelial cell-cell adhesion, inflammatory cytokine- and angiogenic growth factor-induced signals impinge on the vascular endothelial cadherin (VE-cadherin) complex, the central component of endothelial adherens junctions. This study demonstrates that junction remodeling takes place at

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. 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.

  15. 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. PMID:26046524

  16. Molecular anatomy of interendothelial junctions in human blood-brain barrier microvessels.

    Directory of Open Access Journals (Sweden)

    Andrzej W Vorbrodt

    2004-07-01

    Full Text Available Immunogold cytochemical procedure was used to study the localization at the ultrastructural level of interendothelial junction-associated protein molecules in the human brain blood microvessels, representing the anatomic site of the blood-brain barrier (BBB. Ultrathin sections of Lowicryl K4M-embedded biopsy specimens of human cerebral cortex obtained during surgical procedures were exposed to specific antibodies, followed by colloidal gold-labeled secondary antibodies. All tight junction-specific integral membrane (transmembrane proteins--occludin, junctional adhesion molecule (JAM-1, and claudin-5--as well as peripheral zonula occludens protein (ZO-1 were highly expressed. Immunoreactivity of the adherens junction-specific transmembrane protein VE-cadherin was of almost similar intensity. Immunolabeling of the adherens junction-associated peripheral proteins--alpha-catenin, beta-catenin, and p120 catenin--although positive, was evidently less intense. The expression of gamma-catenin (plakoglobin was considered questionable because solitary immunosignals (gold particles appeared in only a few microvascular profiles. Double labeling of some sections made possible to observe strict colocalization of the junctional molecules, such as occludin and ZO-1 or JAM-1 and VE-cadherin, in the interendothelial junctions. We found that in human brain microvessels, the interendothelial junctional complexes contain molecular components specific for both tight and adherens junctions. It is assumed that the data obtained can help us find the immunodetectable junctional molecules that can serve as sensitive markers of normal or abnormal function of the BBB.

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

    International Nuclear Information System (INIS)

    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 cm2/mg enter the silicon surface. The authors also found that the SEU current may cause soft errors with a probability of more than 10−12 per event, which was obtained by approximate solution of the ordinary differential equation of switching probability when the intrinsic critical current (IC0) became less than 30 μA

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

    Science.gov (United States)

    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.

  19. Tight junctions in Hailey-Hailey and Darier’s diseases

    Directory of Open Access Journals (Sweden)

    Laura Raiko

    2009-11-01

    Full Text Available Hailey-Hailey disease (HHD and Darier’s disease (DD are caused by mutations in Ca2+-ATPases with the end result of desmosomal disruption and suprabasal acantholysis. Tight junctions (TJ are located in the granular cell layer in normal skin and contribute to the epidermal barrier. Aberrations in the epidermal differentiation, such as in psoriasis, have been shown to lead to changes in the expression of TJ components. Our aim was to elucidate the expression and dynamics of the TJ proteins during the disruption of desmosomes in HHD and DD lesions. Indirect immunofluorescence and avidin-biotin labeling for TJ, desmosomal and adherens junction proteins, and subsequent analyses with the confocal laser scanning microscope were carried out on 14 HHD and 14 DD skin samples. Transepidermal water loss (TEWL was measured in normal and lesional epidermis of nine HHD and eight DD patients to evaluate the function of the epidermal barrier in HHD and DD skin. The localization of TJ proteins claudin-1, claudin-4, ZO-1, and occludin in perilesional HHD and DD epidermis was similar to that previously described in normal skin. In HHD lesions the tissue distribution of ZO-1 expanded to the acantholytic spinous cells. In agreement with previous findings, desmoplakin was localized intracellularly. In contrast claudin-1 and ZO-1 persisted in the cell-cell contact sites of acantholytic cells. TEWL was increased in the lesional skin. The current results suggest that TJ components follow different dynamics in acantholysis of HHD and DD compared to desmosomal and adherens junction proteins.

  20. Japanese encephalitis virus disrupts cell-cell junctions and affects the epithelial permeability barrier functions.

    Directory of Open Access Journals (Sweden)

    Tanvi Agrawal

    Full Text Available Japanese encephalitis virus (JEV is a neurotropic flavivirus, which causes viral encephalitis leading to death in about 20-30% of severely-infected people. Although JEV is known to be a neurotropic virus its replication in non-neuronal cells in peripheral tissues is likely to play a key role in viral dissemination and pathogenesis. We have investigated the effect of JEV infection on cellular junctions in a number of non-neuronal cells. We show that JEV affects the permeability barrier functions in polarized epithelial cells at later stages of infection. The levels of some of the tight and adherens junction proteins were reduced in epithelial and endothelial cells and also in hepatocytes. Despite the induction of antiviral response, barrier disruption was not mediated by secreted factors from the infected cells. Localization of tight junction protein claudin-1 was severely perturbed in JEV-infected cells and claudin-1 partially colocalized with JEV in intracellular compartments and targeted for lysosomal degradation. Expression of JEV-capsid alone significantly affected the permeability barrier functions in these cells. Our results suggest that JEV infection modulates cellular junctions in non-neuronal cells and compromises the permeability barrier of epithelial and endothelial cells which may play a role in viral dissemination in peripheral tissues.

  1. A missense mutation (G1506E) in the adhesion G domain of laminin-5 causes mild junctional epidermolysis bullosa.

    Science.gov (United States)

    Scaturro, Maria; Posteraro, Patrizia; Mastrogiacomo, Alessandro; Zaccaria, Maria Letizia; De Luca, Naomi; Mazzanti, Cinzia; Zambruno, Giovanna; Castiglia, Daniele

    2003-09-12

    Laminin-5 is the major adhesion ligand for epithelial cells. Mutations in the genes encoding laminin-5 cause junctional epidermolysis bullosa (JEB), a recessive inherited disease characterized by extensive epithelial-mesenchymal disadhesion. We describe a JEB patient compound heterozygote for two novel mutations in the gene (LAMA3) encoding the laminin alpha3 chain. The maternal mutation (1644delG) generates mRNA transcripts that undergo nonsense-mediated decay. The paternal mutation results in the Gly1506-->Glu substitution (G1506E) within the C-terminal globular region of the alpha3 chain (G domain). Mutation G1506E affects the proper folding of the fourth module of the G domain and results in the retention of most of the mutated polypeptide within the endoplasmic reticulum (ER). However, scant amounts of the mutated laminin-5 are secreted, undergo physiologic extracellular maturation, and correctly localize within the cutaneous basement membrane zone in patient's skin. Our findings represent the first demonstration of an ER-retained mutant laminin-5 leading to a mild JEB phenotype. PMID:12943669

  2. A stop-gain in the laminin, alpha 3 gene causes recessive junctional epidermolysis bullosa in Belgian Blue cattle.

    Science.gov (United States)

    Sartelet, Arnaud; Harland, Chad; Tamma, Nico; Karim, Latifa; Bayrou, Calixte; Li, Wanbo; Ahariz, Naima; Coppieters, Wouter; Georges, Michel; Charlier, Carole

    2015-10-01

    Four newborn purebred Belgian Blue calves presenting a severe form of epidermolysis bullosa were recently referred to our heredo-surveillance platform. SNP array genotyping followed by autozygosity mapping located the causative gene in a 8.3-Mb interval on bovine chromosome 24. Combining information from (i) whole-genome sequencing of an affected calf, (ii) transcriptomic data from a panel of tissues and (iii) a list of functionally ranked positional candidates pinpointed a private G to A nucleotide substitution in the LAMA3 gene that creates a premature stop codon (p.Arg2609*) in exon 60, truncating 22% of the corresponding protein. The LAMA3 gene encodes the alpha 3 subunit of the heterotrimeric laminin-332, a key constituent of the lamina lucida that is part of the skin basement membrane connecting epidermis and dermis layers. Homozygous loss-of-function mutations in this gene are known to cause severe junctional epidermolysis bullosa in human, mice, horse, sheep and dog. Overall, our data strongly support the causality of the identified gene and mutation. PMID:26370913

  3. 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

  4. 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.

  5. Ultrastructural studies of the junctional complex in the musculature of the arrow-worm (Sagitta setosa) (Chaetognatha).

    Science.gov (United States)

    Duvert, M; Gros, D; Salat, C

    1980-01-01

    In the A fibres of the primary musculature of Sagitta, the junctional complex is made up of three kinds of junctions. From the apex to the base they occur in the following order: an apical zonula adherens, a columnar zonula then columnar maculae intermingled with gap junction. Each columnar junction joins two intracellular filament networks in adjacent cells; this cytoskeleton is largely developed around the nucleus of the A fibres and in close relation with the contractile apparatus, especially at the I band level. The B fibres, which never reach the general cavity, lack zonula adherens and columnar zonula. The columnar junction constitutes a new type of junction which seems to belong to the adherens kind. At their level fibrous columns cross the extracellular space, joining the membranes. Each column faces two cytoplasmic densities localized against the cytoplasmic leaflets of the membranes. A cytoskeleton composed of bunldes of cytoplasmic filaments is in close contact with these cytoplasmic densities. The great number of columnar junctions and associated cytoskeleton assure the cohesion of the tissue and the distribution of contractile forces in the absence of connective tissue. The abundance of gap junctions can account for the metabolic and ionic coupling of the fibres. PMID:7189067

  6. 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

  7. Gap Junctions

    OpenAIRE

    Goodenough, Daniel A.; Paul, David L.

    2009-01-01

    Gap junctions are aggregates of intercellular channels that permit direct cell–cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hex...

  8. Regulation of cytoskeletal organization and junctional remodeling by the atypical cadherin Fat

    OpenAIRE

    Marcinkevicius, Emily; Zallen, Jennifer A.

    2013-01-01

    The atypical cadherin Fat is a conserved regulator of planar cell polarity, but the mechanisms by which Fat controls cell shape and tissue structure are not well understood. Here, we show that Fat is required for the planar polarized organization of actin denticle precursors, adherens junction proteins and microtubules in the epidermis of the late Drosophila embryo. In wild-type embryos, spatially regulated cell-shape changes and rearrangements organize cells into highly aligned columns. Junc...

  9. 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.

  10. 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

  11. Tight Junction Disruption Induced by Type 3 Secretion System Effectors Injected by Enteropathogenic and Enterohemorrhagic Escherichia coli.

    Science.gov (United States)

    Ugalde-Silva, Paul; Gonzalez-Lugo, Octavio; Navarro-Garcia, Fernando

    2016-01-01

    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. PMID:27606286

  12. 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.

  13. 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.

  14. 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

  15. Neisseria gonorrhoeae induced disruption of cell junction complexes in epithelial cells of the human genital tract.

    Science.gov (United States)

    Rodríguez-Tirado, Carolina; Maisey, Kevin; Rodríguez, Felipe E; Reyes-Cerpa, Sebastián; Reyes-López, Felipe E; Imarai, Mónica

    2012-03-01

    Pathogenic microorganisms, such as Neisseria gonorrhoeae, have developed mechanisms to alter epithelial barriers in order to reach subepithelial tissues for host colonization. The aim of this study was to examine the effects of gonococci on cell junction complexes of genital epithelial cells of women. Polarized Ishikawa cells, a cell line derived from endometrial epithelium, were used for experimental infection. Infected cells displayed a spindle-like shape with an irregular distribution, indicating potential alteration of cell-cell contacts. Accordingly, analysis by confocal microscopy and cellular fractionation revealed that gonococci induced redistribution of the adherens junction proteins E-cadherin and its adapter protein β-catenin from the membrane to a cytoplasmic pool, with no significant differences in protein levels. In contrast, gonococcal infection did not induce modification of either expression or distribution of the tight junction proteins Occludin and ZO-1. Similar results were observed for Fallopian tube epithelia. Interestingly, infected Ishikawa cells also showed an altered pattern of actin cytoskeleton, observed in the form of stress fibers across the cytoplasm, which in turn matched a strong alteration on the expression of fibronectin, an adhesive glycoprotein component of extracellular matrix. Interestingly, using western blotting, activation of the ERK pathway was detected after gonococcal infection while p38 pathway was not activated. All effects were pili and Opa independent. Altogether, results indicated that gonococcus, as a mechanism of pathogenesis, induced disruption of junction complexes with early detaching of E-cadherin and β-catenin from the adherens junction complex, followed by a redistribution and reorganization of actin cytoskeleton and fibronectin within the extracellular matrix. PMID:22146107

  16. A recurrent homozygous nonsense mutation within the LAMA3 gene as a cause of Herlitz junctional epidermolysis bullosa in patients of Pakistani ancestry: evidence for a founder effect.

    Science.gov (United States)

    McGrath, J A; Kivirikko, S; Ciatti, S; Moss, C; Christiano, A M; Uitto, J

    1996-04-01

    The anchoring filament protein laminin 5 is abnormally expressed in the skin of patients with Herlitz junctional epidermolysis bullosa (H-JEB). In this study, we performed mutational analysis on genomic DNA from a H-JEB child of first-cousin Pakistani parents, and identified a homozygous C-to-T transition in the LAMA3 gene of laminin 5 resulting in a premature termination codon (CGA-TGA) on both alleles. This mutation, R650X, has been previously reported in two other seemingly unrelated H-JEB individuals of Pakistani ancestry. Although this mutation may represent a mutational hotspot within the LAMA3 gene, haplotype analysis based on a silent intragenic polymorphism (GCC/GCG, alanine 429; GenBank no. L34155), and on three flanking microsatellite polymorphism (D18S45, D18S478, and D18S480), suggests that a common ancestral allele may be present in all three cases. PMID:8618022

  17. 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.

  18. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-04-01

    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.

  19. 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.

  20. 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.

  1. 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

    Directory of Open Access Journals (Sweden)

    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.

  2. Novel and recurrent mutations in the laminin-5 genes causing lethal junctional epidermolysis bullosa: molecular basis and clinical course of Herlitz disease.

    Science.gov (United States)

    Mühle, Christiane; Jiang, Qiu-Jie; Charlesworth, Alexandra; Bruckner-Tuderman, Leena; Meneguzzi, Guerrino; Schneider, Holm

    2005-01-01

    Herlitz disease (H-JEB), the lethal form of junctional epidermolysis bullosa, is a rare genodermatosis presenting from birth with widespread erosions and blistering of skin and mucosae because of tissue cleavage within the epidermal basement membrane. Mutations in any of the three genes encoding the alpha3, beta3 and gamma2 chains of laminin-5 underlie this recessively inherited disorder. Here, we report the molecular basis and clinical course of H-JEB in 12 patients. Two novel nonsense mutations in the gene LAMA3 (E281X and K1299X) and a novel frame-shift mutation in the gene LAMB3 (1628insG) leading to a premature termination codon were identified by DNA sequencing and confirmed by restriction fragment length polymorphism analysis. In the four patients affected, neither the resulting truncated polypeptide chains nor assembled laminin-5 protein were detectable by immunofluorescence. Three patients were found to be heterozygous for the known hotspot mutation R635X and the recurrent mutations Q373X or 29insC in the gene LAMB3, whereas five others were homozygous for R635X. Significant variations in the disease progression and survival times between 1 and 30 months in this group of H-JEB patients emphasised the impact of modifying factors and the importance of immunostaining or mRNA assessment as parallel diagnostic methods. Interestingly, the only patients who survived for longer than 6 months were four females carrying the mutation R635X homozygously. In one of them, the clinical course may have been improved by treatment with artificial skin equivalents. These data may stimulate further investigation of genotype-phenotype correlations and facilitate mutation analysis and genetic counselling of affected families. PMID:15538630

  3. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  5. 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)

    Elfers, Kristin; Marr, Isabell; 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

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Striatins as plaque molecules of zonulae adhaerentes in simple epithelia, of tessellate junctions in stratified epithelia, of cardiac composite junctions and of various size classes of lateral adherens junctions in cultures of epithelia- and carcinoma-derived cells

    OpenAIRE

    Franke, Werner W; Rickelt, Steffen; Zimbelmann, Ralf; Dörflinger, Yvette; Kuhn, Caecilia; Frey, Norbert; Heid, Hans; Rosin-Arbesfeld, Rina

    2014-01-01

    Proteins of the striatin family (striatins 1–4; sizes ranging from 90 to 110 kDa on SDS-polyacrylamide gel electrophoresis) are highly homologous in their amino acid sequences but can differ in their cell-type-specific gene expression patterns and biological functions. In various cell types, we have found one, two or three polypeptides of this evolutionarily old and nearly ubiquitous family of proteins known to serve as scaffold proteins for diverse protein complexes. Light and electron micro...

  8. 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...

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Solitons in Josephson junctions

    Science.gov (United States)

    Ustinov, A. V.

    1998-11-01

    Magnetic flux quanta in Josephson junctions, often called fluxons, in many cases behave as solitons. A review of recent experiments and modelling of fluxon dynamics in Josephson circuits is presented. Classic quasi-one-dimensional junctions, stacked junctions (Josephson superlattices), and discrete Josephson transmission lines (JTLs) are discussed. Applications of fluxon devices as high-frequency oscillators and digital circuits are also addressed.

  12. 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.

  13. 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.

  14. Herlitz junctional epidermolysis bullosa.

    Science.gov (United States)

    Laimer, Martin; Lanschuetzer, Christoph M; Diem, Anja; Bauer, Johann W

    2010-01-01

    Junctional epidermolysis bullosa type Herlitz (JEB-H) is the autosomal recessively inherited, more severe variant of "lucidolytic" JEB. Characterized by generalized, extensive mucocutaneous blistering at birth and early lethality, this devastating condition is most often caused by homozygous null mutations in the genes LAMA3, LAMB3, or LAMC2, each encoding for 1 of the 3 chains of the heterotrimer laminin-332. The JEB-H subtype usually presents as a severe and clinically diverse variant of the EB group of mechanobullous genodermatoses. This article outlines the epidemiology, presentation, and diagnosis of JEB-H. Morbidity and mortality are high, necessitating optimized protocols for early (including prenatal) diagnosis and palliative care. Gene therapy remains the most promising perspective. PMID:19945616

  15. Imaging of cervicothoracic junction trauma

    OpenAIRE

    Kaewlai, Rathachai

    2013-01-01

    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...

  16. Reinforcing endothelial junctions prevents microvessel permeability increase and tumor cell adhesion in microvessels in vivo

    Science.gov (United States)

    Fu, Bingmei M.; Yang, Jinlin; Cai, Bin; Fan, Jie; Zhang, Lin; Zeng, Min

    2015-10-01

    Tumor cell adhesion to the microvessel wall is a critical step during tumor metastasis. Vascular endothelial growth factor (VEGF), a secretion of tumor cells, can increase microvessel permeability and tumor cell adhesion in the microvessel. To test the hypothesis that inhibiting permeability increase can reduce tumor cell adhesion, we used in vivo fluorescence microscopy to measure both microvessel permeability and adhesion rates of human mammary carcinoma MDA-MB-231 cells in post-capillary venules of rat mesentery under the treatment of VEGF and a cAMP analog, 8-bromo-cAMP, which can decrease microvessel permeability. By immunostaining adherens junction proteins between endothelial cells forming the microvessel wall, we further investigated the structural mechanism by which cAMP abolishes VEGF-induced increase in microvessel permeability and tumor cell adhesion. Our results demonstrate that 1) Pretreatment of microvessels with cAMP can abolish VEGF-enhanced microvessel permeability and tumor cell adhesion; 2) Tumor cells prefer to adhere to the endothelial cell junctions instead of cell bodies; 3) VEGF increases microvessel permeability and tumor cell adhesion by compromising endothelial junctions while cAMP abolishes these effects of VEGF by reinforcing the junctions. These results suggest that strengthening the microvessel wall integrity can be a potential approach to inhibiting hematogenous tumor metastasis.

  17. 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.

  18. Mutant B-Raf(V600E) Promotes Melanoma Paracellular Transmigration by Inducing Thrombin-mediated Endothelial Junction Breakdown.

    Science.gov (United States)

    Zhang, Pu; Feng, Shan; Liu, Gentao; Wang, Heyong; Zhu, Huifeng; Ren, Qiao; Bai, Huiyuan; Fu, Changliang; Dong, Cheng

    2016-01-29

    Tumor invasiveness depends on the ability of tumor cells to breach endothelial barriers. In this study, we investigated the mechanism by which the adhesion of melanoma cells to endothelium regulates adherens junction integrity and modulates tumor transendothelial migration (TEM) by initiating thrombin generation. We found that the B-Raf(V600E) mutation in metastatic melanoma cells up-regulated tissue factor (TF) expression on cell membranes and promoted thrombin production. Co-culture of endothelial monolayers with metastatic melanoma cells mediated the opening of inter-endothelial spaces near melanoma cell contact sites in the presence of platelet-free plasma (PFP). By using small interfering RNA (siRNA), we demonstrated that B-Raf(V600E) and TF silencing attenuated the focal disassembly of adherens junction induced by tumor contact. Vascular endothelial-cadherin (VE-cadherin) disassembly was dependent on phosphorylation of p120-catenin on Ser-879 and VE-cadherin on Tyr-658, Tyr-685, and Tyr-731, which can be prevented by treatment with the thrombin inhibitor, hirudin, or by silencing the thrombin receptor, protease-activated receptor-1, in endothelial cells. We also provided strong evidence that tumor-derived thrombin enhanced melanoma TEM by inducing ubiquitination-coupled VE-cadherin internalization, focal adhesion formation, and actin assembly in endothelium. Confocal microscopic analysis of tumor TEM revealed that junctions transiently opened and resealed as tumor cells accomplished TEM. In addition, in the presence of PFP, tumor cells preferentially transmigrated via paracellular routes. PFP supported melanoma transmigration under shear conditions via a B-Raf(V600E)-thrombin-dependent mechanism. We concluded that the activation of thrombin generation by cancer cells in plasma is an important process regulating melanoma extravasation by disrupting endothelial junction integrity. PMID:26504080

  19. 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.

  20. 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...

  1. Neuromuscular junctional disorders.

    Science.gov (United States)

    Girija, A S; Ashraf, V V

    2008-07-01

    Neuromuscular junctional disorders (NMJ) in children are distinct entity. They may be acquired or hereditary. They pose problem in diagnosis because of the higher occurrence of sero negative Myasthenia Gravis (MG) cases in children. The identity of MusK antibody positivity in a good percentage of sero negative cases further adds to problems in diagnosis. The Congenital Myasthenic Syndrome (CMS) which are rare disorders of hereditary neuromuscular transmission (NMT) has to be differentiated because immunotherapy has no benefit in this group. Molecular genetic studies of these diseases helps to identify specific type of CMS which is important as other drugs like Fluoxetine, Quinidine are found to be effective in some. In infancy, all can manifest as floppy infant syndrome. The important key to diagnosis is by detailed electrophysiological studies including repetitive nerve stimulation at slow and high rates and its response to anticholinesterases and estimation of Acetyl choline receptor antibodies. Other causes of neuromuscular transmission defects viz. snake venom poisoning and that due to drugs are discussed. PMID:18716738

  2. 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.

  3. Self-organizing actomyosin patterns on the cell cortex at epithelial cell-cell junctions.

    Science.gov (United States)

    Moore, Thomas; Wu, Selwin K; Michael, Magdalene; Yap, Alpha S; Gomez, Guillermo A; Neufeld, Zoltan

    2014-12-01

    The behavior of actomyosin critically determines morphologically distinct patterns of contractility found at the interface between adherent cells. One such pattern is found at the apical region (zonula adherens) of cell-cell junctions in epithelia, where clusters of the adhesion molecule E-cadherin concentrate in a static pattern. Meanwhile, E-cadherin clusters throughout lateral cell-cell contacts display dynamic movements in the plane of the junctions. To gain insight into the principles that determine the nature and organization of these dynamic structures, we analyze this behavior by modeling the 2D actomyosin cell cortex as an active fluid medium. The numerical simulations show that the stability of the actin filaments influences the spatial structure and dynamics of the system. We find that in addition to static Turing-type patterns, persistent dynamic behavior occurs in a wide range of parameters. In the 2D model, mechanical stress-dependent actin breakdown is shown to produce a continuously changing network of actin bridges, whereas with a constant breakdown rate, more isolated clusters of actomyosin tend to form. The model qualitatively reproduces the dynamic and stable patterns experimentally observed at the junctions between epithelial cells. PMID:25468344

  4. p38 MAPK Regulates Cavitation and Tight Junction Function in the Mouse Blastocyst

    Science.gov (United States)

    Bell, Christine E.; Watson, Andrew J.

    2013-01-01

    Blastocyst formation is essential for implantation and maintenance of pregnancy and is dependent on the expression and coordinated function of a series of proteins involved in establishing and maintaining the trans-trophectoderm ion gradient that enables blastocyst expansion. These consist of Na/K-ATPase, adherens junctions, tight junctions (TJ) and aquaporins (AQP). While their role in supporting blastocyst formation is established, the intracellular signaling pathways that coordinate their function is unclear. The p38 MAPK pathway plays a role in regulating these proteins in other cell types and is required for embryo development at the 8–16 cell stage, but its role has not been investigated in the blastocyst. Hypothesis p38 MAPK regulates blastocyst formation by regulating blastocyst formation gene expression and function. Methods Embryos were cultured from the early blastocyst stage for 12 h or 24 h in the presence of a potent and specific p38 MAPK inhibitor, SB 220025. Blastocyst expansion, hatching, gene family expression and localization, TJ function and apoptosis levels were analyzed. Results Inhibition of the p38 MAPK pathway reduced blastocyst expansion and hatching, increased tight junction permeability, affected TJP1 localization, reduced Aqp3 expression, and induced a significant increase in apoptosis. Conclusion The p38 MAPK pathway coordinates the overall events that regulate blastocyst formation. PMID:23593143

  5. 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.

  6. 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.

  7. Potent In Vitro Protection Against PM[Formula: see text]-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

    2016-04-01

    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

  8. Junction-FET dosimeter

    International Nuclear Information System (INIS)

    The performance of a new junction-FET dosimeter and its application to the beam profile measurement are presented. One of the two junction FET's making up an astable multivibrator is used as a small-size (approx.0.4x0.4 mm) high-level dose detector. The irradiated dose can be estimated by the amount of the decrease of the oscillator period of the multivibrator. The distinct advantages in its small size and superior resistive property to radiation effect enable us to measure the cross-sectional profile of the electron beam from a linac with high spatial resolution of about 0.4 mm

  9. 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

  10. 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.

  11. 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...

  12. Lactational exposure of phthalate causes long-term disruption in testicular architecture by altering tight junctional and apoptotic protein expression in Sertoli cells of first filial generation pubertal Wistar rats.

    Science.gov (United States)

    Sekaran, S; Balaganapathy, P; Parsanathan, R; Elangovan, S; Gunashekar, J; Bhat, F A; Jagadeesan, A

    2015-06-01

    Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental contaminant and a well-known endocrine disruptor (ED) that interferes with the reproductive function in both humans and animals. This study aimed to find out the impact of lactational exposure of DEHP in testes of first filial generation (F1) progeny male rat postnatal day (PND)-60. Lactating dams were orally treated with DEHP (0, 1, 10 and 100 mg/kg body weight/day, respectively) from the PND-1 to PND-21. Rats were killed at PND 60. Testes were removed and used for histological analysis and for isolation of Sertoli cells (SCs). The histoarchitecture of DEHP-treated rats showed disturbed testicular structure. DEHP-treated rats also showed increased oxidative stress by decreasing antioxidant levels in the SCs; it disrupted SC tight junctional proteins occludin, claudin, junctional adhesion molecule, zona occludens protein-1 (ZO-1), zona occludens protein-2 (ZO-2), and afadin-6 (AF-6), increased apoptosis by altering the apoptotic genes Bax, cytochrome c, caspase-8, -9, -3 and antiapoptotic gene Bcl-2. It is concluded that early postnatal exposure to DEHP disturbs histoarchitecture of testis and SC function in pubertal Wistar rats. PMID:25352649

  13. 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.

  14. Oncostatin M induces upregulation of claudin-2 in rodent hepatocytes coinciding with changes in morphology and function of tight junctions

    International Nuclear Information System (INIS)

    In rodent livers, integral tight junction (TJ) proteins claudin-1, -2, -3, -5 and -14 are detected and play crucial roles in the barrier to keep bile in bile canaculi away from the blood circulation. Claudin-2 shows a lobular gradient increasing from periportal to pericentral hepatocytes, whereas claudin-1 and -3 are expressed in the whole liver lobule. Although claudin-2 expression induces cation-selective channels in tight junctions of epithelial cells, the physiological functions and regulation of claudin-2 in hepatocytes remain unclear. Oncostatin M (OSM) is a multifunctional cytokine implicated in the differentiation of hepatocytes that induces formation of E-cadherin-based adherens junctions in fetal hepatocytes. In this study, we examined whether OSM could induce expression and function of claudin-2 in rodent hepatocytes, immortalized mouse and primary cultured proliferative rat hepatocytes. In the immortalized mouse and primary cultured proliferative rat hepatocytes, treatment with OSM markedly increased mRNA and protein of claudin-2 together with formation of developed networks of TJ strands. The increase of claudin-2 enhanced the paracellular barrier function which depended on molecular size. The increase of claudin-2 expression induced by OSM in rodent hepatocytes was regulated through distinct signaling pathways including PKC. These results suggest that expression of claudin-2 in rodent hepatocytes may play a specific role as controlling the size of paracellular permeability in the barrier to keep bile in bile canaculi

  15. 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.

  16. 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.

  17. METAL-SEMICONDUCTOR JUNCTIONS

    OpenAIRE

    Flores, F.; Sánchez-Dehesa, J.; Guinea, F.

    1984-01-01

    In spite of many different models there seems to be a general lack of understanding about the mechanism of Schottky barrier formation. In order to elucidate this mechanism for covalent semiconductors, we present theoretical selfconsistent calculations for abrupt Si-Ag, C-Ag and Si-H-Ag junctions. Our results are in good agreement with the available experimental evidence, and show that the interface Fermi level is controlled by a density of states that appears in the semiconductor gap as a res...

  18. Josephson junction simulation of neurons

    OpenAIRE

    Crotty, Patrick; Schult, Daniel; Segall, Ken

    2010-01-01

    With the goal of understanding the intricate behavior and dynamics of collections of neurons, we present superconducting circuits containing Josephson junctions that model biologically realistic neurons. These "Josephson junction neurons" reproduce many characteristic behaviors of biological neurons such as action potentials, refractory periods, and firing thresholds. They can be coupled together in ways that mimic electrical and chemical synapses. Using existing fabrication technologies, lar...

  19. Fluid Flow at Branching Junctions

    OpenAIRE

    Sochi, Taha

    2013-01-01

    The flow of fluids at branching junctions plays important kinematic and dynamic roles in most biological and industrial flow systems. The present paper highlights some key issues related to the flow of fluids at these junctions with special emphasis on the biological flow networks particularly blood transportation vasculature.

  20. 食管胃结合部腺癌流行趋势、病因及防治%Adenocarcinoma of the esophagogastric junction:epidemic trends, causes, prevention and therapy

    Institute of Scientific and Technical Information of China (English)

    陈志峰

    2012-01-01

    Population epidemiology analysis of esophageal cancer for the high risk region in China finds that: incidence of esophageal squamous cell carcinoma has decreased and that of adenocarcinoma of the esophagogastric junction(AEG) has increased significantly. European and American scholars believe that obesity and stomach-esophageal reflux disease are independent risk factors of the two types of cancer. In the high risk region of esophageal cancer in China, the heritability is (29.67±4.32)% and the segregation ratio is 0.181, 95% CI (0.15-0.21). Esophageal cancer belongs to multi-gene genetic disease. According to the evolution of the pathological mechanism of gastric cardia adenocarcinoma and the WHO's clinical treatment principles, cardiac severe atypicalhyperplasia were mainly endoscopic resection in the high riskregion in China. Paying attention to the intervention ofatrophic gastritis or active gastritis may be the realisticmeasures to reduce intestinal metaplasia and the incidence ofAEG.%国内食管癌高发区人群流行病学分析发现:食管鳞癌发病率下降;食管胃结合部腺癌(AEG)发病率显著上升.欧美学者认为,肥胖和胃食管反流性疾病是这两类肿瘤的独立危险因素.我国食管癌高发区的遗传度为(29.67±4.32)%,分离比0.181,95%CI:0.15~0.21,属于多基因遗传病.根据AEG的病理演变机理和WHO的临床处理原则,目前食管癌高发区对贲门重度不典型增生者主要采用内镜下切除;而重视萎缩性或活动性胃炎的干预治疗,对降低肠化,减少AEG的发病也可能是比较现实的措施之一.

  1. Macroscopic quantum effects in capacitively- and inductively-coupled intrinsic Josephson junctions

    Science.gov (United States)

    Koyama, T.; Machida, M.

    2009-03-01

    A theory for macroscopic quantum tunneling (MQT) in intrinsic Josephson junction stacks is formulated. Both capacitive and inductive couplings between junctions are taken into account. We calculate the escape rate in the switching to the first resistive branch in the quantum regime. It is shown that the enhancement of the escape rate is caused mainly by the capacitive coupling between junctions in IJJ's with small in-plane area of ~ 1μm2.

  2. 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.

  3. TRANSITIONAL FLOW IN CHANNEL JUNCTIONS

    Institute of Scientific and Technical Information of China (English)

    NI Han-gen; LIU Ya-kun

    2004-01-01

    On the basis of energy and continuity equations a simple one-dimensional formulation was proposed to predict the transitional flow at an open-channel junction. An empilical relation between the junction losses, the junction angle, and the discharge ratio was suggested which agrees well with the experimental results. The results calculated by the present formulation for the depth ratio were compared with the results of earlier one-dimensional formulations and experiments. It is found that the present results coincide better with experiments than those of others.

  4. 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.

  5. 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

  6. 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.

  7. The nanostructure of myoendothelial junctions contributes to signal rectification between endothelial and vascular smooth muscle cells

    DEFF Research Database (Denmark)

    Brasen, Jens Christian; Jacobsen, Jens Christian Brings; von Holstein-Rathlou, Niels-Henrik

    2012-01-01

    may rectify a signal between the two cell layers. The rectification is caused by the asymmetrical structure of the myoendothelial junction. Because the head of the myoendothelial junction is separated from the cell it is attached to by a narrow neck region, a signal generated in the neighboring cell...

  8. Thermal conductance of superlattice junctions

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Simon; McGaughey, Alan J. H., E-mail: mcgaughey@cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2015-05-15

    We use molecular dynamics simulations and the lattice-based scattering boundary method to compute the thermal conductance of finite-length Lennard-Jones superlattice junctions confined by bulk crystalline leads. The superlattice junction thermal conductance depends on the properties of the leads. For junctions with a superlattice period of four atomic monolayers at temperatures between 5 and 20 K, those with mass-mismatched leads have a greater thermal conductance than those with mass-matched leads. We attribute this lead effect to interference between and the ballistic transport of emergent junction vibrational modes. The lead effect diminishes when the temperature is increased, when the superlattice period is increased, and when interfacial disorder is introduced, but is reversed in the harmonic limit.

  9. Thermal conductance of superlattice junctions

    Directory of Open Access Journals (Sweden)

    Simon Lu

    2015-05-01

    Full Text Available We use molecular dynamics simulations and the lattice-based scattering boundary method to compute the thermal conductance of finite-length Lennard-Jones superlattice junctions confined by bulk crystalline leads. The superlattice junction thermal conductance depends on the properties of the leads. For junctions with a superlattice period of four atomic monolayers at temperatures between 5 and 20 K, those with mass-mismatched leads have a greater thermal conductance than those with mass-matched leads. We attribute this lead effect to interference between and the ballistic transport of emergent junction vibrational modes. The lead effect diminishes when the temperature is increased, when the superlattice period is increased, and when interfacial disorder is introduced, but is reversed in the harmonic limit.

  10. Voltage dependence of the differential capacitance of a p+-n junction

    International Nuclear Information System (INIS)

    The dependences of the differential capacitance and current of a p+-n junction with a uniformly doped n region on the voltage in the junction region are calculated. The p+-n junction capacitance controls the charge change in the junction region taking into account a change in the electric field of the quasi-neutral n region and a change in its bipolar drift mobility with increasing excess charge-carrier concentration. It is shown that the change in the sign of the p+-n junction capacitance with increasing injection level is caused by a decrease in the bipolar drift mobility as the electron-hole pair concentration in the n region increases. It is shown that the p+-n junction capacitance decreases with increasing reverse voltage and tends to a constant positive value.

  11. Josephson junctions with ferromagnetic interlayer

    International Nuclear Information System (INIS)

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlOx/Pd0.82Ni0.18/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 π-coupling is observed for a thickness dF=6 nm of the ferromagnetic Pd0.82Ni0.18 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 Pd0.82Ni0.18 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.

  12. 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.

  13. 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.

  14. Age-dependant expression of alpha-macula adherens protein in rat heart%α-黏着斑蛋白在大鼠心脏表达分布随增龄变化的特征

    Institute of Scientific and Technical Information of China (English)

    张光谋; 吴俊琢; 张艳芬; 郭志坤

    2005-01-01

    BACKGROUND: Macula adherens protein is found closely associated with congenital cardiac malformation and myocardial differentiation. OBJECTIVE: To investigate the expression characteristics of α-macula adherens protein in rat heart, as well as the property of age-dependant expression during myocardial growth. DESIGN: Randomized controlled, observational comparative study. SETTING: Department of Cell Biology of Xinxiang Medical College; Department of Bioengineering and Agricultural Economics of Puyang Vocational Technical School. MATERIALS: This study was conducted at the Morphological Laboratory of Xinxiang Medical College between January and June 2003. Totally 28 Wistar rats of clean grade were divided into infant group, youth group,middle-age group, and old-age group with 7 rats in each group. METHODS: All rats were anaesthetized and then cardiac tissues were cut into consecutive coronal slices of 5 μm thick. The expression of α-macula adherens protein in rat myocardium of infant, youth, middle-age and oldage groups was detected using IHC method. The positive cells displayed brownish yellow granules on the surface, cytoplasm and intercalated disc. Routine HE staining was performed on all specimens for structural comparison. MAIN OUTCOME MEASURES: The expression of α-macula adherens protein in rat myocardium of different groups. RESULTS: All the 28 rats entered the final results analysis. ① α-macula adherens protein was found to be expressed in myocardium in atrium, ventricle, papilla muscles and interventricular septum. ② In infant rats, the expression of α-macula adherens protein was mainly observed in intercalated disc at the end of myocardium, with less expression on cell surface and in cytoplasm; in contrast, α-macula adherens protein in young, middleaged and old rats was found to be typically expressed in intercalated disc at the end of myocardium. CONCLUSION: The expression of α-macula adherens protein displays age-dependant manner during rat

  15. 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.

  16. 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.

  17. 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.

  18. INFLUENCE OF SODIUM ARSENITE ON GAP JUNCTION COMMUNICATION IN RAT LIVER EPITHELIAL CELLS

    Science.gov (United States)

    Influence of sodium arsenite on gap junction communication in rat-Iiver epitheiial cells. Arsenic is known to cause certain types of cancers, hepatitis, cirrhosis and neurological disorders as well as cardiovascular and reproductive effects and skin lesions. The mechanism...

  19. 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.

  20. Physical properties of the junction of scandium and carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Fang LIN

    2011-01-01

    Using first-principles calculations, the contact between the scandium (Sc) and semiconducting carbon nanotube (CNT)is investigated. This is one of the best quality of n-type contacts. Two junction models with (8,0) CNT on low-index Sc surfaces are constructed to elucidate the structural and electronic properties of Sc/CNT junctions. Analyses based on density of states and charge difference reveal that strong chemical bonds are formed between Sc and C atoms due to hybrid states of Sc 3d state and C 2π state. With respect to Ti(0001)/CNT junction, we find the dipole layer formed at the interface of Sc(0001)/CNT is comparable with that of Ti(0001)/CNT but gives a negative barrier at the interface. This indicates that the excellent contact properties of Sc metal electrode are caused by its low work function and excellent binding with CNT.

  1. Transport properties of molecular junctions

    CERN Document Server

    Zimbovskaya, Natalya A

    2013-01-01

    A comprehensive overview of the physical mechanisms that control electron transport and the characteristics of metal-molecule-metal (MMM) junctions is presented. As far as possible, methods and formalisms presented elsewhere to analyze electron transport through molecules are avoided. This title introduces basic concepts—a description of the electron transport through molecular junctions—and briefly describes relevant experimental methods. Theoretical methods commonly used to analyze the electron transport through molecules are presented. Various effects that manifest in the electron transport through MMMs, as well as the basics of density-functional theory and its applications to electronic structure calculations in molecules are presented. Nanoelectronic applications of molecular junctions and similar systems are discussed as well. Molecular electronics is a diverse and rapidly growing field. Transport Properties of Molecular Junctions presents an up-to-date survey of the field suitable for researchers ...

  2. NbN tunnel junctions

    International Nuclear Information System (INIS)

    All-niobium nitride Josephon junctions have been prepared successfully using a new processing called SNOP: Selective Niobium (nitride) Overlap Process. Such a process involves the ''trilayer'' deposition on the whole wafer before selective patterning of the electrodes by optically controlled dry reactive ion etching. Only two photomask levels are need to define an ''overlap'' or a ''cross-type'' junction with a good accuracy. The properties of the niobium nitride films deposited by DC-magnetron sputtering and the surface oxide growth are analysed. The most critical point to obtain high quality and high gap value junctions resides in the early stage of the NbN counterelectrode growth. Some possibilities to overcome such a handicap exist even if the fabrication needs substrate temperatures below 2500C

  3. Myasthenia and related disorders of the neuromuscular junction

    OpenAIRE

    Spillane, Jennifer; Beeson, David J; Kullmann, Dimitri M.

    2010-01-01

    Abstract Our understanding of transmission at the neuromuscular junction has increased greatly in recent years. We now recognise a wide variety of autoimmune and genetic diseases that affect this specialised synapse, causing muscle weakness and fatigue. These disorders greatly affect quality of life and rarely can be fatal. Myasthenia Gravis is the most common disorder and is most commonly caused by auto-antibodies targeting postsynaptic acetylcholine receptors (AChRs). Antibodie...

  4. 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.

  5. 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...

  6. Soliton excitations in Josephson tunnel junctions

    DEFF Research Database (Denmark)

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

    1982-01-01

    A detailed numerical study of a sine-Gordon model of the Josephson tunnel junction is compared with experimental measurements on junctions with different L / λJ ratios. The soliton picture is found to apply well on both relatively long (L / λJ=6) and intermediate (L / λJ=2) junctions. We find good...

  7. delta-biased Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Koshelet, V.;

    2010-01-01

    Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...

  8. 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...

  9. Hidden quantum mirage by negative refraction in semiconductor P-N junctions

    Science.gov (United States)

    Zhang, Shu-Hui; Zhu, Jia-Ji; Yang, Wen; Lin, Hai-Qing; Chang, Kai

    2016-08-01

    We predict a robust quantum interference phenomenon in a semiconductor P-N junction: with a local pump on one side of the junction, the response of a local probe on the other side behaves as if the disturbance emanates not from the pump but instead from its mirror image about the junction. This phenomenon follows from the matching of Fermi surfaces of the constituent materials, thus it is robust against the details of the junction (e.g., width, potential profile, and even disorder), in contrast to the widely studied anomalous focusing caused by negative refraction. The recently fabricated P-N junctions in 2D semiconductors provide ideal platforms to explore this phenomenon and its applications to dramatically enhance charge and spin transport as well as carrier-mediated long-range correlation.

  10. 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

  11. Fabrication of high quality ferromagnetic Josephson junctions

    International Nuclear Information System (INIS)

    We present ferromagnetic Nb/Al2O3/Ni60Cu40/Nb Josephson junctions (SIFS) with an ultrathin Al2O3 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 c spreads less than 2% was obtained

  12. 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.

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

    OpenAIRE

    Abdelaziz Amine; Yamina Mir; Mimoun Zazoui

    2013-01-01

    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 p...

  14. Seebeck effect in molecular junctions

    International Nuclear Information System (INIS)

    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. (topical review)

  15. 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.

  16. Counting Statistics in Nanoscale Junctions

    OpenAIRE

    Liu, Yu-Shen; Chen, Yu-Chang

    2010-01-01

    We present first-principles calculations for moments of the current up to the third order in atomic-scale junctions. The quantum correlations of the current are calculated using the current operator in terms of the wave functions obtained self-consistently within the static density-functional theory. We investigate the relationships of the conductance, the second, and the third moment of the current for carbon atom chains of various lengths bridging two metal electrodes in the linear and nonl...

  17. 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.

  18. 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.

  19. Thermoelectric efficiency of molecular junctions.

    Science.gov (United States)

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

    2016-09-21

    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. PMID:27420149

  20. Bipolar junction transistor models for circuit simulation of cosmic-ray-induced soft errors

    Science.gov (United States)

    Benumof, R.; Zoutendyk, J.

    1984-01-01

    This paper examines bipolar junction transistor models suitable for calculating the effects of large excursions of some of the variables determining the operation of a transistor. Both the Ebers-Moll and Gummel-Poon models are studied, and the junction and diffusion capacitances are evaluated on the basis of the latter model. The most interesting result of this analysis is that a bipolar junction transistor when struck by a cosmic particle may cause a single event upset in an electronic circuit if the transistor is operated at a low forward base-emitter bias.

  1. 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.

  2. 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').

  3. 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.

  4. 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......The motion of fluxons of the same polarity in three vertically stacked Josephson junctions is studied. In this configuration the difference between exterior and interior junctions plays a more important role than in other configurations with several interior junctions. Below the Swihart velocity c......-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...

  5. String junction as a baryonic constituent

    CERN Document Server

    Kalashnikova, Yu S

    1995-01-01

    We extend the model for QCD string with quarks to consider the Mercedes Benz string configuration describing the three-quark baryon. Under the assumption of adiabatic separation of quark and string junction motion we formulate and solve the classical equation of motion for the junction.We dare to quantize the motion of the junction, and discuss the impact of these modes on the baryon spectra.

  6. Quantum Dynamics of a d-wave Josephson Junction

    Science.gov (United States)

    Bauch, Thilo

    2007-03-01

    Thilo Bauch ^1, Floriana Lombardi ^1, Tobias Lindstr"om ^2, Francesco Tafuri ^3, Giacomo Rotoli ^4, Per Delsing ^1, Tord Claeson ^1 1 Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96 G"oteborg, Sweden. 2 National Physical Laboratory, Queens Road, Teddington, Middlesex TW11 0LW, UK. 3 Istituto Nazionale per la Fisica della Materia-Dipartimento Ingegneria dell'Informazione, Seconda Universita di Napoli, Aversa (CE), Italy. 4 Dipartimento di Ingegneria Meccanica, Energetica e Gestionale, Universita of L'Aquila, Localita Monteluco, L'Aquila, Italy. We present direct observation of macroscopic quantum properties in an all high critical temperature superconductor d-wave Josephson junction. Although dissipation caused by low energy excitations is expected to strongly suppress quantum effects we demonstrate macroscopic quantum tunneling [1] and energy level quantization [2] in our d-wave Josephson junction. The results clearly indicate that the role of dissipation mechanisms in high temperature superconductors has to be revised, and may also have consequences for a new class of solid state ``quiet'' quantum bit with superior coherence time. We show that the dynamics of the YBCO grain boundary Josephson junctions fabricated on a STO substrate are strongly affected by their environment. As a first approximation we model the environment by the stray capacitance and stray inductance of the junction electrodes. The total system consisting of the junction and stray elements has two degrees of freedom resulting in two characteristic resonance frequencies. Both frequencies have to be considered to describe the quantum mechanical behavior of the Josephson circuit. [1] T. Bauch et al, Phys. Rev. Lett. 94, 087003 (2005). [2] T. Bauch et al, Science 311, 57 (2006).

  7. Grand Junction Remedial Action Program

    International Nuclear Information System (INIS)

    The Grand Junction Remedial Action Program (hereinafter referred to as the Program) originated in 1972 due to a recognized need to reduce the levels of radiation found in some of the structures identified in Grand Junction, Colorado that were constructed in part with uranium mill tailings. Out of over 640 locations eventually identified as qualifying for corrective action, the Program performed remedial construction on 594 of them. The owners of over 45 unremediated structures either did not wish to participate in the voluntary Program, or the structures were torn down, burned down, or were abandoned before the Program could take action on them. Because this was the first remedial action program of its type, and because its task was to reduce the radiation levels as soon as practical, there was no time for lengthly research and development of remedial methods or techniques. Trial and error combined with basic engineering and health physics produced a Program that learned as it progressed. At a cost of $22.7 million over a 15-year period, a substantial portion of the community had radiation exposure reduced because many public buildings such as schools, churches, and businesses, as well as private residences were remediated. 21 refs., 10 figs., 6 tabs

  8. Keratin 76 is required for tight junction function and maintenance of the skin barrier.

    Directory of Open Access Journals (Sweden)

    Tia DiTommaso

    2014-10-01

    Full Text Available Keratins are cytoskeletal intermediate filament proteins that are increasingly being recognised for their diverse cellular functions. Here we report the consequences of germ line inactivation of Keratin 76 (Krt76 in mice. Homozygous disruption of this epidermally expressed gene causes neonatal skin flaking, hyperpigmentation, inflammation, impaired wound healing, and death prior to 12 weeks of age. We show that this phenotype is associated with functionally defective tight junctions that are characterised by mislocalization of the integral protein CLDN1. We further demonstrate that KRT76 interacts with CLDN1 and propose that this interaction is necessary to correctly position CLDN1 in tight junctions. The mislocalization of CLDN1 has been associated in various dermopathies, including the inflammatory disease, psoriasis. These observations establish a previously unknown connection between the intermediate filament cytoskeleton network and tight junctions and showcase Krt76 null mice as a possible model to study aberrant tight junction driven skin diseases.

  9. Linker-dependent Junction Formation Probability in Single-Molecule Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Pil Sun; Kim, Taekyeong [HankukUniversity of Foreign Studies, Yongin (Korea, Republic of)

    2015-01-15

    We compare the junction formation probabilities of single-molecule junctions with different linker molecules by using a scanning tunneling microscope-based break-junction technique. We found that the junction formation probability varies as SH > SMe > NH2 for the benzene backbone molecule with different types of anchoring groups, through quantitative statistical analysis. These results are attributed to different bonding forces according to the linker groups formed with Au atoms in the electrodes, which is consistent with previous works. Our work allows a better understanding of the contact chemistry in the metal.molecule junction for future molecular electronic devices.

  10. 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...

  11. Spin, Vibrations and Radiation in Superconducting Junctions

    NARCIS (Netherlands)

    Padurariu, C.

    2013-01-01

    This thesis presents the theoretical study of superconducting transport in several devices based on superconducting junctions. The important feature of these devices is that the transport properties of the junction are modified by the interaction with another physical system integrated in the super

  12. Hall effect in NS and SNS junctions

    OpenAIRE

    Zhou, F.; Spivak, B.

    1997-01-01

    Hall effect in SN and SNS junctions is considered. It is shown that at small temperature the Hall voltage is significantly suppressed as compared to its normal metal value. The time dependence of the Hall voltage in SNS junctions has a form of narrow pulses with the Josephson frequency.

  13. 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

  14. Genetics Home Reference: junctional epidermolysis bullosa

    Science.gov (United States)

    ... Junctional epidermolysis bullosa results from mutations in the LAMA3 , LAMB3 , LAMC2 , and COL17A1 genes. Mutations in each ... of all cases of junctional epidermolysis bullosa . The LAMA3 , LAMB3 , and LAMC2 genes each provide instructions for ...

  15. Electrophysiological study in neuromuscular junction disorders

    OpenAIRE

    Cherian, Ajith; Baheti, Neeraj N.; Iype, Thomas

    2013-01-01

    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 i...

  16. Zipper and freeway shear zone junctions

    Science.gov (United States)

    Passchier, Cees; Platt, John

    2016-04-01

    Ductile shear zones are usually presented as isolated planar high-strain domains in a less deformed wall rock, characterised by shear sense indicators such as characteristic deflected foliation traces. Many shear zones, however, form branched systems and if movement on such branches is contemporaneous, the resulting geometry can be complicated and lead to unusual fabric geometries in the wall rock. For Y-shaped shear zone junctions with three simultaneously operating branches, and with slip directions at a high angle to the branch line, eight basic types of shear zone triple junctions are possible, divided into three groups. The simplest type, called freeway junctions, have similar shear sense on all three branches. If shear sense is different on the three branches, this can lead to space problems. Some of these junctions have shear zone branches that join to form a single branch, named zipper junctions, or a single shear zone which splits to form two, known as wedge junctions. Closing zipper junctions are most unusual, since they form a non-active high-strain zone with opposite deflection of foliations. Shear zipper and shear wedge junctions have two shear zones with similar shear sense, and one with the opposite sense. All categories of shear zone junctions show characteristic flow patterns in the shear zone and its wall rock. Shear zone junctions with slip directions normal to the branch line can easily be studied, since ideal sections of shear sense indicators lie in the plane normal to the shear zone branches and the branch line. Expanding the model to allow slip oblique and parallel to the branch line in a full 3D setting gives rise to a large number of geometries in three main groups. Slip directions can be parallel on all branches but oblique to the branch line: two slip directions can be parallel and a third oblique, or all three branches can have slip in different directions. Such more complex shear zone junctions cannot be studied to advantage in a

  17. Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

    International Nuclear Information System (INIS)

    Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q ∼ 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement

  18. 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 biased...... at different points in the current-voltage characteristic. Both numerical calculations based on the Tien-Gordon theory and 70-GHz microwave experiments have confirmed the wide dynamic range (more than 15-dB attenuation for one stage) and the low insertion loss in the ''open'' state. The performance of a fully...... integrated submillimeter receiver circuit which comprises a flux-flow oscillator (FFO) as local oscillator, a superconducting variable attenuator, and a microwave SIS detector with tuned-out capacitance is also reported....

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Graded junction termination extensions for electronic devices

    Science.gov (United States)

    Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

    2007-01-01

    A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

  4. Exploring tight junction alteration using double fluorescent probe combination of lanthanide complex with gold nanoclusters

    Science.gov (United States)

    Wang, Xinyi; Wang, Na; Yuan, Lan; Li, Na; Wang, Junxia; Yang, Xiaoda

    2016-08-01

    Tight junctions play a key role in restricting or regulating passage of liquids, ions and large solutes through various biological barriers by the paracellular route. Changes in paracellular permeation indicate alteration of the tight junction. However, it is very difficult to obtain the structural change information by measuring paracellular flux based on transepithelial electrical resistance or using fluorescein-labeled dextrans. Here we show that the BSA and GSH stabilized gold nanoclusters exhibit marginal cytotoxicity and pass through the MDCK monolayer exclusively through the paracellular pathway. We propose a double fluorescence probe strategy, the combination of a proven paracellular indicator (europium complex) with fluorescent gold nanoclusters. We calculate changes of structural parameters in tight junctions based on determination of the diffusion coefficients of the probes. Two different types of tight junction openers are used to validate our strategy. Results show that EDTA disrupts tight junction structures and induces large and smooth paracellular pore paths with an average radius of 17 nm, but vanadyl complexes induce paths with the radius of 6 nm. The work suggests that the double fluorescence probe strategy is a useful and convenient approach for in vitro investigation of tight junction structural alternations caused by pharmacological or pathological events.

  5. 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.

  6. Motorway junction design with emphasis on traffic performance and safety assesment - case study junction Ljubljana Rudnik

    OpenAIRE

    Mlaker, Pavel

    2013-01-01

    Thesis encompasses reconstruction predesign of the motorway junction Ljubljana Rudnik into motorway interchange. In this area is intended to be the junction of main arterial road with highway network, while today serves only as a minor junction of Rudnik and Ig area on the motorway. The purpose of reconstruction is to enable free traffic flow on most congested directions of the interchange, but also preserve the present function, in which Ig and Rudnik area are connected with the motorway. Bu...

  7. Current trends in salivary gland tight junctions.

    Science.gov (United States)

    Baker, Olga J

    2016-01-01

    Tight junctions form a continuous intercellular barrier between epithelial cells that is required to separate tissue spaces and regulate selective movement of solutes across the epithelium. They are composed of strands containing integral membrane proteins (e.g., claudins, occludin and tricellulin, junctional adhesion molecules and the coxsackie adenovirus receptor). These proteins are anchored to the cytoskeleton via scaffolding proteins such as ZO-1 and ZO-2. In salivary glands, tight junctions are involved in polarized saliva secretion and barrier maintenance between the extracellular environment and the glandular lumen. This review seeks to provide an overview of what is currently known, as well as the major questions and future research directions, regarding tight junction expression, organization and function within salivary glands. PMID:27583188

  8. 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.

  9. Bond resistances in molecular junctions

    Science.gov (United States)

    Painelli, Anna

    2006-03-01

    The description of molecular contacts is one of the hardest problems in modeling molecular junctions. In common approaches macroscopic leads ensure a finite potential drop and hence a driving force for the current. Recently, a different strategy is emerging where a steady-state DC current is forced in the molecule, by making resort to Lagrange multipliers, or by drawing a magnetic flux through the molecule. The strategy is promising, but two main problems remain to be solved: (1) the calculation of the potential drop needed to sustain the current, and (2) the definition of the potential profile along the molecule. Here the Joule law is used to evaluate the potential drop from the electrical power spent on the molecule, and continuity constraints for steady-state DC current are implemented to get information on the potential profile. Borrowing powerful concepts from the field of molecular spectroscopy, emphasis is put on the molecule, while clamping information about contacts in the molecular relaxation matrix. The molecule is described in a real-space approach, leading to a suggestive analogy between the molecule and an electrical circuit where resistances are associated with chemical bonds.

  10. Controllable spin transport in ferromagnetic graphene junctions

    OpenAIRE

    Yokoyama, Takehito

    2008-01-01

    We study spin transport in normal/ferromagnetic/normal graphene junctions where a gate electrode is attached to the ferromagnetic graphene. We find that due to the exchange field of the ferromagnetic graphene, spin current through the junctions has an oscillatory behavior with respect to the chemical potential in the ferromagnetic graphene, which can be tuned by the gate voltage. Especially, we obtain a controllable spin current reversal by the gate voltage. Our prediction of high controllabi...

  11. Heat dissipation in atomic-scale junctions

    OpenAIRE

    Lee, Woochul; Kim, Kyeongtae; Jeong, Wonho; Zotti, Linda Angela; Pauly, Fabian; Cuevas, Juan Carlos; Reddy, Pramod

    2013-01-01

    Atomic and single-molecule junctions represent the ultimate limit to the miniaturization of electrical circuits. They are also ideal platforms for testing quantum transport theories that are required to describe charge and energy transfer in novel functional nanometre-scale devices. Recent work has successfully probed electric and thermoelectric phenomena in atomic-scale junctions. However, heat dissipation and transport in atomic-scale devices remain poorly characterized owing to experimenta...

  12. 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.

  13. Pseudospin dynamics in multimode polaritonic Josephson junctions

    OpenAIRE

    Pavlovic, G.; Malpuech, G.; Shelykh, I. A.

    2012-01-01

    We analyzed multimode Josephson junctions with exciton-polaritons (polaritonic Josephson junctions) when several coupling mechanisms of fundamental and excited states are present. The applied method is based on Keldysh-Green function formalism and takes into account polariton pseudospin. We found that mean value of circular polarization degree in intrinsic Josephson oscillations and microscopic quantum self-trapping follow an oscillator behavior whose renormalizes due to intermode interaction...

  14. The junctional complex in the intestine of Sagitta setosa (Chaetognatha): the paired septate junction.

    Science.gov (United States)

    Duvert, M; Gros, D; Salat, C

    1980-04-01

    The junctional complex of the intestine of Sagitta setosa has been studied in tissues stained with uranyl acetate or after lanthanum impregnation, and by freeze-cleavage. All types of junctions have been characterized in both perpendicular and tangential planes. From the apex to the base of the cell the following junctions occur in this order: a zonula adhaerens; a septate junction where the septa occur in pairs; a pleated sheet septate junction; and numerous gap junctions of the A-type. From the upper part of the cells inwards to the septate junction, the membranes follow a relatively straight path. In the lower part of the cells the membranes are deeply interdigitating. At the intersection between 3 cells a very different junction is to be observed where small units, periodically disposed, bind the membranes of the 3 adjoining cells. Each unit is composed of 3 short segments which bind the cell membranes to a central ring 16.6 +/- 2.3 nm in outer diameter. The paired septate junction constitutes a new type. Its main features are that the septa are paired and occur in 2 formations, one the 'loose formation', with elements between the septa of each pair, and the other, a 'tight formation'. After lanthanum impregnation, the thickness of each septum is seen to be about 3 nm and the undulation period 12.6 +/- 1.6 nm. On freeze-fractures 10-nm particles are found on crests on the PF face and in furrows on the EF face. The possible significance of this type of junction is discussed. The junctional complex described is analogous to those found in various invertebrate epithelia. PMID:6105159

  15. 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.

  16. Herlitz junctional epidermolysis bullosa : diagnostic features, mutational profile, incidence and population carrier frequency in the Netherlands

    NARCIS (Netherlands)

    Yuen, W. Y.; Lemmink, H. H.; van Dijk-Bos, K. K.; Sinke, R. J.; Jonkman, M. F.

    2011-01-01

    Background Junctional epidermolysis bullosa, type Herlitz (JEB-H) is a lethal, autosomal recessive blistering disease caused by null mutations in the genes coding for the lamina lucida/densa adhesion protein laminin-332 (LAMB3, LAMA3 and LAMC2). Objectives To present the diagnostic features and mole

  17. 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

    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....

  18. 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…

  19. Josephson tunnel junctions with ferromagnetic interlayer

    International Nuclear Information System (INIS)

    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 Al2O3 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 π 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, π) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-π Josephson junction. At a certain temperature this 0-π 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 Φ0. 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 → 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.)

  20. 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.)

  1. 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.

  2. 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.

  3. Particle detection with superconducting tunnel junctions

    International Nuclear Information System (INIS)

    At the Institute of Experimental Nuclear Physics of the University of Karlsruhe (TH) and at the Institute for Nuclear Physics of the Kernforschungszentrum Karlsruhe we started to produce superconducting tunnel junctions and to investigate them for their suitability as particle detectors. The required facilities for the production of tunnel junctions and the experimental equipments to carry out experiments with them were erected. Experiments are presented in which radiations of different kinds of particles could successfully be measured with the tunnel junctions produced. At first we succeeded in detectioning light pulses of a laser. In experiments with alpha-particles of an energy of 4,6 MeV the alpha-particles were detected with an energy resolution of 1,1%, and it was shown in specific experiments that the phonons originating from the deposition of energy by an alpha-particle in the substrate can be detected with superconducting tunnel junctions at the surface. On that occasion it turned out that the signals could be separated with respect to their point of origin (tunnel junction, contact leads, substrate). Finally X-rays with an energy of 6 keV were detected with an energy resolution of 8% in a test arrangement that makes use of the so-called trapping effect to read out a larger absorber volume. (orig.)

  4. 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.

  5. 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......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...

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Theory for collective macroscopic tunneling in high- Tc intrinsic Josephson junctions

    Science.gov (United States)

    Machida, M.; Koyama, T.

    2007-10-01

    On the basis of the theory for the capacitive coupling in intrinsic Josephson junctions (IJJ's), we theoretically study the macroscopic quantum tunneling in the switching dynamics into the voltage states in IJJ. The effective action obtained by using the path integral formalism reveals that the capacitive coupling splits each of the lowest and higher quantum levels, which are given inside Josephson potential barrier of the single junction derived by dropping off the coupling, into levels composed of the number of junction (N). This level splitting can cause multiple low-frequency Rabi-oscillations and enhance the switching probability compared to the conventional Caldeira-Leggett theory. Furthermore, a possibility as a naturally built-in multi-qubit is discussed.

  13. 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.

  14. Josephson junctions with ferromagnetic alloy interlayer

    International Nuclear Information System (INIS)

    Josephson junctions are used as active devices in superconducting electronics and quantum information technology. Outstanding properties are their distinct non-linear electrical characteristics and a usually sinusoidal relation between the current and the superconducting phase difference across the junction. In general the insertion of ferromagnetic material in the barrier of a Josephson junction is associated with a suppression of superconducting correlations. But also new phenomena can arise which may allow new circuit layouts and enhance the performance of applications. This thesis presents a systematic investigation for two concepts to fabricate Josephson junctions with a rather uncommon negative critical current. Such devices exhibit an intrinsic phase slip of π between the electrodes, so they are also known as π junctions. Both studies go well beyond existing experiments and in one system a π junction is shown for the first time. All the thin film junctions are based on superconducting Nb electrodes. In a first approach, barriers made from Si and Fe were investigated with respect to the realisation of π junctions by spin-flip processes. The distribution of Fe in the Si matrix was varied from pure layers to disperse compounds. The systematic fabrication of alloy barriers was facilitated by the development of a novel timing-based combinatorial sputtering technique for planetary deposition systems. An orthogonal gradient approach allowed to create binary layer libraries with independent variations of thickness and composition. Second, Nb vertical stroke AlOx vertical stroke Nb vertical stroke Ni60Cu40 vertical stroke Nb (SIsFS) double barrier junctions were experimentally studied for the occurrence of proximity effect induced order parameter oscillations. Detailed dependencies of the critical current density on the thickness of s-layer and F-layer were acquired and show a remarkable agreement to existing theoretical predictions. Especially a variation of jc

  15. Tunnel junction based memristors as artificial synapses

    Directory of Open Access Journals (Sweden)

    Andy eThomas

    2015-07-01

    Full Text Available We prepared magnesia, tantalum oxide and barium titanate based junction structures and investigated their memristive properties. The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use. Here, we increased the amplitude of the resistance change from 10% up to 100%. Utilizing the memristive properties, we looked into the use of the junction structures as artificial synapses. We observed analogs of long-term potentiation, long-term depression and spike-time dependent plasticity in these simple two terminal devices. Finally, we suggest a possible pathway of these devices towards their integration in neuromorphic systems for storing analog synaptic weights and supporting the implementation of biologically plausible learning mechanisms.

  16. 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.

  17. Josephson junctions with ferromagnetic alloy interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Himmel, Nico

    2015-07-23

    Josephson junctions are used as active devices in superconducting electronics and quantum information technology. Outstanding properties are their distinct non-linear electrical characteristics and a usually sinusoidal relation between the current and the superconducting phase difference across the junction. In general the insertion of ferromagnetic material in the barrier of a Josephson junction is associated with a suppression of superconducting correlations. But also new phenomena can arise which may allow new circuit layouts and enhance the performance of applications. This thesis presents a systematic investigation for two concepts to fabricate Josephson junctions with a rather uncommon negative critical current. Such devices exhibit an intrinsic phase slip of π between the electrodes, so they are also known as π junctions. Both studies go well beyond existing experiments and in one system a π junction is shown for the first time. All the thin film junctions are based on superconducting Nb electrodes. In a first approach, barriers made from Si and Fe were investigated with respect to the realisation of π junctions by spin-flip processes. The distribution of Fe in the Si matrix was varied from pure layers to disperse compounds. The systematic fabrication of alloy barriers was facilitated by the development of a novel timing-based combinatorial sputtering technique for planetary deposition systems. An orthogonal gradient approach allowed to create binary layer libraries with independent variations of thickness and composition. Second, Nb vertical stroke AlO{sub x} vertical stroke Nb vertical stroke Ni{sub 60}Cu{sub 40} vertical stroke Nb (SIsFS) double barrier junctions were experimentally studied for the occurrence of proximity effect induced order parameter oscillations. Detailed dependencies of the critical current density on the thickness of s-layer and F-layer were acquired and show a remarkable agreement to existing theoretical predictions. Especially

  18. Synchronized switching in a josephson junction crystal.

    Science.gov (United States)

    Leib, Martin; Hartmann, Michael J

    2014-06-01

    We consider a superconducting coplanar waveguide resonator where the central conductor is interrupted by a series of uniformly spaced Josephson junctions. The device forms an extended medium that is optically nonlinear on the single photon level with normal modes that inherit the full nonlinearity of the junctions but are nonetheless accessible via the resonator ports. For specific plasma frequencies of the junctions, a set of normal modes clusters in a narrow band and eventually becomes entirely degenerate. Upon increasing the intensity of a red detuned drive on these modes, we observe a sharp and synchronized switching from low-occupation quantum states to high-occupation classical fields, accompanied by a pronounced jump from low to high output intensity. PMID:24949766

  19. Spin currents in TFT-Josephson junction

    International Nuclear Information System (INIS)

    The spin of the Cooper pair in a triplet superconductor provides a new degree of freedom in Josephson junction physics. This can be accessed by using a magnetically-active tunneling barrier, leading to a rich variety of unconventional Josephson effects. Because of the triplet state of the pairing wavefunction, triplet superconductor junctions in general also display a Josephson spin current, which can flow even when the equilibrium charge current is vanishing. Using the quasiclassical Green's function theory, we have examined the more general situation of a magnetically-active barrier which does not conserve the spin of a tunneling Cooper-pair. We demonstrate that the Josephson spin currents on either side of the barrier need not be identical, with the magnitude, sign and orientation all allowed to differ. Not only do our calculations enhance the physical understanding of transport through triplet superconductor junctions, but they also open the possibility of novel spintronic Josephson devices.

  20. 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.

  1. Electronic Veselago lensing in graphene PN junctions

    Science.gov (United States)

    Dean, Cory

    Ballistic electrons in a uniform 2D electron gas (2DEG) behave in close analogy to light propagating through an optical medium. In the absence of impurity scattering, electrons follow straight-line trajectories, while the associated de Broglie wavelength can give rise to interference and diffraction. Here we present measurements of ballistic graphene devices in which a graphite gate is used to realize an atomically-smooth junction. We demonstrate unambiguous signatures of negative refraction across a PN junction, paving the way for electron optics inspired by Veselago lensing. Comparison with theoretical simulations reveals the importance of the junction profile towards this effort. Opportunities for future device designs that may take advantage of these effects will be discussed.

  2. 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.

  3. Scale resolved simulations of the OECD/NEA–Vattenfall T-junction benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Höhne, Thomas, E-mail: t.hoehne@hzdr.de

    2014-04-01

    Mixing of fluids in T-junction geometries is of significant interest for nuclear safety research. The most prominent example is the thermal striping phenomena in piping T-junctions, where hot and cold streams join and turbulently mix, however not completely or not immediately at the T-junction. This result in significant temperature fluctuations near the piping wall, either at the side of the secondary pipe branch or at the opposite side of the main branch pipe. The wall temperature fluctuation can cause cyclical thermal stresses and subsequently fatigue cracking of the wall. Thermal mixing in a T-junction has been studied for validation of CFD-calculations. A T-junction thermal mixing test was carried out at the Älvkarleby Laboratory of Vattenfall Research and Development (VRD) in Sweden. Data from this test have been reserved specifically for a OECD CFD benchmark exercise. The computational results show that RANS fail to predict a realistic mixing between the fluids. The results were significantly better with scale-resolving methods such as LES, showing fairly good predictions of the velocity field and mean temperatures. The calculation predicts also similar fluctuations and frequencies observed in the model test.

  4. 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.

  5. Esophagogastric junction distensibility in hiatus hernia.

    Science.gov (United States)

    Lottrup, C; McMahon, B P; Ejstrud, P; Ostapiuk, M A; Funch-Jensen, P; Drewes, A M

    2016-07-01

    Hiatus hernia is known to be an important risk factor for developing gastroesophageal reflux disease. We aimed to use the endoscopic functional lumen imaging probe (EndoFLIP) to evaluate the functional properties of the esophagogastric junction. EndoFLIP assessments were made in 30 patients with hiatus hernia and Barrett's esophagus, and in 14 healthy controls. The EndoFLIP was placed straddling the esophagogastric junction and the bag distended stepwise to 50 mL. Cross-sectional areas of the bag and intra-bag pressures were recorded continuously. Measurements were made in the separate sphincter components and hiatus hernia cavity. EndoFLIP measured functional aspects such as sphincter distensibility and pressure of all esophagogastric junction components and visualized all hiatus hernia present at endoscopy. The lower esophageal sphincter in hiatus hernia patients had a lower pressure (e.g. 47.7 ± 13.0 vs. 61.4 ± 19.2 mm Hg at 50-mL distension volume) and was more distensible (all P hiatus hernia patients, the crural diaphragm had a lower pressure (e.g. 29.6 ± 10.1 vs. 47.7 ± 13.0 mm Hg at 50-mL distension volume) and was more distensible (all P hiatus hernia and to measure the functional properties of the esophagogastric junction. Furthermore, EndoFLIP distinguished the separate esophagogastric junction components in hiatus hernia patients, and may help us understand the biomechanics of the esophagogastric junction and the mechanisms behind hiatal herniation. PMID:25789842

  6. Magnesium gating of cardiac gap junction channels.

    Science.gov (United States)

    Matsuda, Hiroyuki; Kurata, Yasutaka; Oka, Chiaki; Matsuoka, Satoshi; Noma, Akinori

    2010-09-01

    We aimed to study kinetics of modulation by intracellular Mg(2+) of cardiac gap junction (Mg(2+) gate). Paired myocytes of guinea-pig ventricle were superfused with solutions containing various concentrations of Mg(2+). In order to rapidly apply Mg(2+) to one aspect of the gap junction, the non-junctional membrane of one of the pair was perforated at nearly the connecting site by pulses of nitrogen laser beam. The gap junction conductance (G(j)) was measured by clamping the membrane potential of the other cell using two-electrode voltage clamp method. The laser perforation immediately increased G(j), followed by slow G(j) change with time constant of 3.5 s at 10 mM Mg(2+). Mg(2+) more than 1.0 mM attenuated dose-dependently the gap junction conductance and lower Mg(2+) (0.6 mM) increased G(j) with a Hill coefficient of 3.4 and a half-maximum effective concentration of 0.6 mM. The time course of G(j) changes was fitted by single exponential function, and the relationship between the reciprocal of time constant and Mg(2+) concentration was almost linear. Based on the experimental data, a mathematical model of Mg(2+) gate with one open state and three closed states well reproduced experimental results. One-dimensional cable model of thirty ventricular myocytes connected to the Mg(2+) gate model suggested a pivotal role of the Mg(2+) gate of gap junction under pathological conditions. PMID:20553744

  7. 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.

  8. 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.

  9. Electron and Phonon Transport in Molecular Junctions

    DEFF Research Database (Denmark)

    Li, Qian

    Molecular electronics provide the possibility to investigate electron and phonon transport at the smallest imaginable scale, where quantum effects can be investigated and exploited directly in the design. In this thesis, we study both electron transport and phonon transport in molecular junctions...... 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...

  10. Bursting behaviour in coupled Josephson junctions.

    Science.gov (United States)

    Hongray, Thotreithem; Balakrishnan, J; Dana, Syamal K

    2015-12-01

    We report an interesting bow-tie shaped bursting behaviour in a certain parameter regime of two resistive-capacitative shunted Josephson junctions, one in the oscillatory and the other in the excitable mode and coupled together resistively. The burst emerges in both the junctions and they show near-complete synchronization for strong enough couplings. We discuss a possible bifurcation scenario to explain the origin of the burst. An exhaustive study on the parameter space of the system is performed, demarcating the regions of bursting from other solutions. PMID:26723143

  11. 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...... 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....

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. TH-C-BRD-12: Robust Intensity Modulated Proton Therapy Plan Can Eliminate Junction Shifts for Craniospinal Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Liao, L [UT MD Anderson Cancer Center, University of Houston, Houston, TX (United States); Jiang, S [UT MD Anderson Cancer Center, Tianjin Medical University Cancer Instit, Houston, TX (United States); Li, Y [Varian Medical Systems, Houston, TX (United States); Wang, X [UT MD Anderson Cancer Center, Houston, Texas (United States); Li, H; Zhu, X; Sahoo, N; Gillin, M; Mahajan, A; Grosshans, D; Zhang, X [UT MD Anderson Cancer Center, Houston, TX (United States); Lim, G [University of Houston, Houston, Texas (United States)

    2014-06-15

    Purpose: The passive scattering proton therapy (PSPT) technique is the commonly used radiotherapy technique for craniospinal irradiation (CSI). However, PSPT involves many numbers of junction shifts applied over the course of treatment to reduce the cold and hot regions caused by field mismatching. In this work, we introduced a robust planning approach to develop an optimal and clinical efficient techniques for CSI using intensity modulated proton therapy (IMPT) so that junction shifts can essentially be eliminated. Methods: The intra-fractional uncertainty, in which two overlapping fields shift in the opposite directions along the craniospinal axis, are incorporated into the robust optimization algorithm. Treatment plans with junction sizes 3,5,10,15,20,25 cm were designed and compared with the plan designed using the non-robust optimization. Robustness of the plans were evaluated based on dose profiles along the craniospinal axis for the plans applying 3 mm intra-fractional shift. The dose intra-fraction variations (DIV) at the junction are used to evaluate the robustness of the plans. Results: The DIVs are 7.9%, 6.3%, 5.0%, 3.8%, 2.8% and 2.2%, for the robustly optimized plans with junction sizes 3,5,10,15,20,25 cm. The DIV are 10% for the non-robustly optimized plans with junction size 25 cm. The dose profiles along the craniospinal axis exhibit gradual and tapered dose distribution. Using DIVs less than 5% as maximum acceptable intrafractional variation, the overlapping region can be reduced to 10 cm, leading to potential reduced number of the fields. The DIVs are less than 5% for 5 mm intra-fractional shifts with junction size 25 cm, leading to potential no-junction-shift for CSI using IMPT. Conclusion: This work is the first report of the robust optimization on CSI based on IMPT. We demonstrate that robust optimization can lead to much efficient carniospinal irradiation by eliminating the junction shifts.

  17. Spin and valley transports in junctions of Dirac fermions

    OpenAIRE

    Yokoyama, Takehito

    2014-01-01

    We study spin and valley transports in junctions composed of silicene and topological crystalline insulators. We consider normal/magnetic/normal Dirac metal junctions where a gate electrode is attached to the magnetic region. In normal/antiferromagnetic/normal silicene junction, we show that the current through this junction is valley and spin polarized due to the coupling between valley and spin degrees of freedom, and the valley and spin polarizations can be tuned by local application of a ...

  18. Quasiparticle dynamics in superconducting tunnel junctions

    NARCIS (Netherlands)

    Kozorezov, A.G.; Brammertz, G.; Hijmering, R.A.; Wigmore, J.K.; Peacock, A.; Martin, B.; Verhoeve, P.; Golubov, A.A.; Rogalla, H.

    2006-01-01

    Superconducting Tunnel Junctions (STJs) used as single photon detectors possess extreme sensitivity and excellent resolving power. However, like many other cryogenic detectors they operate under extremely non-equilibrium conditions. In order to understand the physics of the non-equilibrium, non-stat

  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. PMID:25553192

  20. Radiation comb generation with extended Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Solinas, P., E-mail: paolo.solinas@spin.cnr.it [SPIN-CNR, Via Dodecaneso 33, 16146 Genova (Italy); Bosisio, R., E-mail: riccardo.bosisio@nano.cnr.it [SPIN-CNR, Via Dodecaneso 33, 16146 Genova (Italy); NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy); Giazotto, F., E-mail: giazotto@sns.it [NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy)

    2015-09-21

    We propose the implementation of a Josephson radiation comb generator based on an extended Josephson junction subject to a time dependent magnetic field. The junction critical current shows known diffraction patterns and determines the position of the critical nodes when it vanishes. When the magnetic flux passes through one of such critical nodes, the superconducting phase must undergo a π-jump to minimize the Josephson energy. Correspondingly, a voltage pulse is generated at the extremes of the junction. Under periodic driving, this allows us to produce a comb-like voltage pulses sequence. In the frequency domain, it is possible to generate up to hundreds of harmonics of the fundamental driving frequency, thus mimicking the frequency comb used in optics and metrology. We discuss several implementations through a rectangular, cylindrical, and annular junction geometries, allowing us to generate different radiation spectra and to produce an output power up to 10 pW at 50 GHz for a driving frequency of 100 MHz.

  1. Graphene-based magnetic tunnel junctions

    Science.gov (United States)

    Cobas, Enrique

    2013-03-01

    Graphene's in-plane transport has been widely researched and has yielded extraordinary carrier mobilities of 105 cm2/Vs and spin diffusion lengths of exceeding 100 μm. These properties bode well for graphene in future electronics and spintronics technologies. Its out-of-plane transport has been far less studied, although its parent material, graphite, shows a large conductance anisotropy. Recent calculations show graphene's interaction with close-packed ferromagnetic metal surfaces should produce highly spin-polarized transport out-of-plane, an enabling breakthrough for spintronics technology. In this work, we fabricate and measure FM/graphene/FM magnetic tunnel junctions using CVD-grown single-layer graphene. The resulting juctions show non-linear current-voltage characteristics and a very weak temperature dependence consistent with charge tunneling transport. Furthermore, we study spin transport across the junction as a function of bias voltage and temperature. The tunneling magnetoresistance (TMR) peaks at two percent for single-layer graphene junctions and exhibits the expected bias asymmetry and a temperature dependence that fits well with established spin-polarized tunneling models. Results of mutli-layer graphene tunnel junctions will also be discussed.

  2. 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...

  3. 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...

  4. TOPICAL REVIEW: Intrinsic Josephson junctions: recent developments

    Science.gov (United States)

    Yurgens, A. A.

    2000-08-01

    Some recent developments in the fabrication of intrinsic Josephson junctions (IJJ) and their application for studying high-temperature superconductors are discussed. The major advantages of IJJ and unsolved problems are outlined. The feasibility of three-terminal devices based on the stacked IJJ is briefly evaluated.

  5. Electric Field Effect in Intrinsic Josephson Junctions

    Science.gov (United States)

    Koyama, T.

    The electric field effect in intrinsic Josephson junction stacks (IJJ's) is investigated on the basis of the capacitively-coupled IJJ model. We clarify the current-voltage characteristics of the IJJ's in the presence of an external electric field. It is predicted that the IJJ's show a dynamical transition to the voltage state as the external electric field is increased.

  6. Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages

    Science.gov (United States)

    Grabert, Hermann

    2015-12-01

    The theory of the dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that, for standard setups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows us to split off the time dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of the dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.

  7. 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.

  8. Shunted-Josephson-junction model. I. The autonomous case

    DEFF Research Database (Denmark)

    Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

    1977-01-01

    The shunted-Josephson-junction model: the parallel combination of a capacitance, a phase-dependent conductance, and an ideal junction element biased by a constant current, is discussed for arbitrary values of the junction parameters. The main objective is to provide a qualitative understanding of...

  9. [Genetic defects and disorders at the neuromuscular junction].

    Science.gov (United States)

    Ohno, Kinji

    2011-07-01

    Genetic defects in molecules expressed at the neuromuscular junction (NMJ) cause congenital myasthenic syndromes (CMSs), which are characterized by muscle weakness, abnormal fatigability, amyotrophy, and minor facial anomalies. Muscle weakness mostly develops under 2 years but is also sometimes seen in adults. Mutations identified to date include (i) muscle nicotinic acetylcholine receptor (AChR) subunits, (ii) rapsyn that anchors and clusters AChRs at the neuromuscular junction, (iii) agrin that is released from the nerve terminal and induces AChR clustering by stimulating the downstream LRP4/MuSK/Dok-7/rapsyn/AChR pathway, (iv) muscle-specific kinase (MuSK) that transmits the AChR-clustering signal from agrin/LRP4 to rapsyn/AChR, (v) Dok-7 that transmits the AChR-clustering signal from agrin/LRP4/MuSK to rapsyn/AChR, (vi) skeletal muscle sodium channel type 1.4 (Nav1.4) that spreads the depolarization potential from the endplate throughout muscle fibers, (vii) collagen Q that anchors acetylcholinesterase to the synaptic basal lamina, and (viii) choline acetyltransferase that resynthesizes acetylcholine from recycled choline at the nerve terminal. In addition, mutations in the heparin sulfate proteoglycan perlecan, which binds to many molecules including collagen Q and dystroglycan, causes Schwartz-Jampel syndrome. Interestingly, mutations in LRP4 cause Cenani-Lenz syndactyly syndrome but not CMS. AChR, MuSK, and LRP4 are also targets of auto-antibodies in myasthenia gravis. In addition, molecules at the NMJ are targets of many other disease states AChRs are blocked by the snake toxin alpha-bungarotoxin and the plant poison curare. The presynaptic SNARE complex is attacked by botulinum toxin. Acetylcholinesterase is inhibited by the nerve gas sarin and by organophosphate pesticides. This review focuses on the molecular bases underlying defects of AChR, rapsyn, Nav1.4, collagen Q, and choline acetyltransferase. PMID:21747136

  10. Myasthenia and related disorders of the neuromuscular junction.

    Science.gov (United States)

    Spillane, Jennifer; Beeson, David J; Kullmann, Dimitri M

    2010-08-01

    Our understanding of transmission at the neuromuscular junction has increased greatly in recent years. We now recognise a wide variety of autoimmune and genetic diseases that affect this specialised synapse, causing muscle weakness and fatigue. These disorders greatly affect quality of life and rarely can be fatal. Myasthenia gravis is the most common disorder and is most commonly caused by autoantibodies targeting postsynaptic acetylcholine receptors. Antibodies to muscle-specific kinase (MuSK) are detected in a variable proportion of the remainder. Treatment is symptomatic and immunomodulatory. Lambert-Eaton myasthenic syndrome is caused by antibodies to presynaptic calcium channels, and approximately 50% of cases are paraneoplastic, most often related to small cell carcinoma of the lung. Botulism is an acquired disorder caused by neurotoxins produced by Clostridium botulinum, impairing acetylcholine release into the synaptic cleft. In addition, several rare congenital myasthenic syndromes have been identified, caused by inherited defects in presynaptic, synaptic basal lamina and postsynaptic proteins necessary for neuromuscular transmission. This review focuses on recent advances in the diagnosis and treatment of these disorders. PMID:20547629

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

    International Nuclear Information System (INIS)

    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

  12. Model building to facilitate understanding of holliday junction and heteroduplex formation, and holliday junction resolution.

    Science.gov (United States)

    Selvarajah, Geeta; Selvarajah, Susila

    2016-07-01

    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 computer-animated video, we included a model building activity using pipe cleaners. Biotechnology undergraduates (n = 108) used the model to simulate Holliday junction and heteroduplex formation, and Holliday junction resolution. Based on student perception, an average of 12.85 and 78.35% students claimed that they completely and partially understood the two concepts, respectively. A test conducted to ascertain their understanding about the two concepts showed that 66.1% of the students provided the correct response to the three multiple choice questions. A majority of the 108 students attributed the inclusion of model building to their better understanding of Holliday junction and heteroduplex formation, and Holliday junction resolution. This underlines the importance of incorporating model building, particularly in concepts that require spatial visualization. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(4):381-390, 2016. PMID:26899144

  13. Preparation of large-area molecular junctions with metallic conducting Langmuir–Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Kengo [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan); Ohnuki, Hitoshi, E-mail: ohnuki@kaiyodai.ac.jp [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan); Shimizu, Daisuke [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan); Imakubo, Tatsuro [Department of Materials and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Tsuya, Daiju [National Institute for Materials Science,1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Izumi, Mitsuru [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan)

    2014-03-03

    Metallic conducting Langmuir–Blodgett (LB) films were used as soft electrodes to fabricate molecular junctions with self-assembled monolayers (SAMs) of alkanethiols (CH{sub 3}(CH{sub 2}){sub n−1}SH) on an Au surface. Alkanethiols can form highly ordered, stable dielectric SAMs on metal surfaces over large areas. However, it is difficult to establish electrical contacts on such SAMs, which has limited their application. In this work, we used metallic conducting LB films composed of bis(ethylenedioxy)tetrathiafulvalene and stearic acid as a soft electrode onto alkanethiol SAMs (C{sub n}-SAM, n = 12, 14, 16, 18) to prepare Au/SAM/metal junctions of relatively large size (∼ 15.6 × 10{sup 3} μm{sup 2}). The current density–voltage (J–V) characteristics across the junctions exhibited rectifying behavior with a ratio R of ∼ 5 (R = |J(V)|/|J(− V)| at ± 1 V). The lower transfer rate corresponding to the electron transport from Au to the LB films exhibited nonlinear J–V characteristics, while the higher transfer rate of electrons from the LB film to Au showed linear J–V characteristics. Kelvin probe force microscopy revealed that the work function of the metallic LB films was smaller than that of Au. The observed rectification behavior is probably caused by different electron transport mechanisms between the two current directions. - Highlights: • Metallic Langmuir–Blodgett (LB) films were used as soft electrodes. • Molecular junctions of metal–alkanethiol–LB films were fabricated. • The current–voltage curve across the junctions exhibited rectifying behavior. • This is the first observation for alkanethiol monolayer junctions. • The work function difference between the electrodes induces the rectification.

  14. 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

  15. Efficacy of dexmedetomidine for the control of junctional ectopic tachycardia after repair of tetralogy of Fallot

    Directory of Open Access Journals (Sweden)

    Randhir S Rajput

    2014-01-01

    Full Text Available Background: Junctional ectopic tachycardia occurs frequently after congenital cardiac surgery and can be a cause of increased morbidity and mortality. Dexmedetomidine (DEX is an a2 adrenoreceptor agonist, has properties of controlling tachyarrhythmia by regulating the sympatho-adrenal system. Objective: To evaluate the efficacy of DEX for control of junctional ectopic tachycardia after repair of Tetralogy of Fallot (TOF. Materials and Methods: Two hundred and twenty pediatric cardiac patients with TOFs were enrolled in a prospective randomized control study. Patients underwent correction surgery. They were divided into two groups, i.e., Group 1 (DEX and Group 2 (control. Heart rate, rhythm, mean arterial pressure (MAP were recorded after the anesthetic induction (T1, after termination of bypass (T2, after 04 hours (T3, and 08 hours after transferring the patient to intensive care unit (ICU; T4. Results: Heart rate was comparable between two groups before starting the drug but statistically significant after bypass until 08 hours after transferring the patient to ICU. Junctional ectopic tachycardia occurred more in Group-2 (20% as compared to Group-1 (9.09%; P = 0.022. Junctional ectopic tachycardia occurs early in Group-2 (0.14 ± 0.527 hours as compared to Group 1 (0.31 ± 1.29 hours; P = 0.042. The duration of junctional ectopic tachycardia was more prolonged in Group-2 (1.63 ± 3.64 hours as compared to Group-1 (0.382 ± 1.60 hours; P = 0.012. The time to withdraw from mechanical ventilation and ICU stay of Group 1 patient was less than of Group 2 patients (P = <0.001. Conclusion: DEX had a therapeutic role in the prevention of junctional ectopic tachycardia in patients undergoing repair for TOF.

  16. 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.

  17. 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...... magnetic field rather than an in-plane field. The conditions under which this occurs are discussed....

  18. Indentation Tests Reveal Geometry-Regulated Stiffening of Nanotube Junctions.

    Science.gov (United States)

    Ozden, Sehmus; Yang, Yang; Tiwary, Chandra Sekhar; Bhowmick, Sanjit; Asif, Syed; Penev, Evgeni S; Yakobson, Boris I; Ajayan, Pulickel M

    2016-01-13

    Here we report a unique method to locally determine the mechanical response of individual covalent junctions between carbon nanotubes (CNTs), in various configurations such as "X", "Y", and "Λ"-like. The setup is based on in situ indentation using a picoindenter integrated within a scanning electron microscope. This allows for precise mapping between junction geometry and mechanical behavior and uncovers geometry-regulated junction stiffening. Molecular dynamics simulations reveal that the dominant contribution to the nanoindentation response is due to the CNT walls stretching at the junction. Targeted synthesis of desired junction geometries can therefore provide a "structural alphabet" for construction of macroscopic CNT networks with tunable mechanical response. PMID:26618517

  19. Cranio-vertebral junction anomaly: atlanto-occipital assimilation.

    Science.gov (United States)

    Pooja Jain, -; Khursheed Raza, -; Chiman Kumari, -; Manisha Hansda, -; Sb Ray, -

    2016-01-01

    Cranio-vertebral junction is a pivot which holds the globe of the head. Bony anomalies at this point are particularly significant because they lodge the spinal cord and lower part of the brain stem. Clinically fusion of the atlas with the lower part of the occiput is known as Atlanto-occipital assimilation or atlas occipitalization, which can be either partial or complete depending upon the extent of fusion. It can present as totally asymptomatic accidental finding or can be a cause behind major neuro-vascular compression. The present case study is an endeavor to explain occipitalization of atlas bone on the basis of embryology and explain its clinical relevance. PMID:27424507

  20. 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.

  1. 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.

  2. Ballistic transport of graphene pnp junctions with embedded local gates

    International Nuclear Information System (INIS)

    We fabricated graphene pnp devices, by embedding pre-defined local gates in an oxidized surface layer of a silicon substrate. With neither deposition of dielectric material on the graphene nor electron-beam irradiation, we obtained high-quality graphene pnp devices without degradation of the carrier mobility even in the local-gate region. The corresponding increased mean free path leads to the observation of ballistic and phase-coherent transport across a local gate 130 nm wide, which is about an order of magnitude wider than reported previously. Furthermore, in our scheme, we demonstrated independent control of the carrier density in the local-gate region, with a conductance map very much distinct from those of top-gated devices. This was caused by the electric field arising from the global back gate being strongly screened by the embedded local gate. Our scheme allows the realization of ideal multipolar graphene junctions with ballistic carrier transport.

  3. Junction conditions in extended Teleparallel gravities

    International Nuclear Information System (INIS)

    In the context of extended Teleparallel gravity theories, we address the issue of junction conditions required to guarantee the correct matching of different regions of spacetime. In the absence of shells/branes, these conditions turn out to be more restrictive than their counterparts in General Relativity as in other extended theories of gravity. In fact, the general junction conditions on the matching hypersurfaces depend on the underlying theory and a new condition on the induced tetrads in order to avoid delta-like distributions in the field equations. This result imposes strict consequences on the viability of standard solutions such as the Einstein-Straus-like construction. We find that the continuity of the scalar torsion is required in order to recover the usual General Relativity results

  4. 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......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 voltage spacing between the satellites and the main flux-flow step corresponds to the second harmonic of the external frequency. We find that the satellite flux-flow modes are characterized by collective excitations propagating through the fluxon chain. These dynamical states can be interpreted as fluxon...... density waves....

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Characterization of magnetic tunnel junction test pads

    DEFF Research Database (Denmark)

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

    2015-01-01

    relies on four-point probe measurements performed with a range of different probe pitches and was originally developed for infinite samples. Using the method of images, we derive a modified CIPT model, which compensates for the insulating boundaries of a finite rectangular sample geometry. We measure...... 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......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...

  11. 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...... measurements were carried out within frequency bands of 1-2 GHz and 0.3-300 kHz. At bias voltages 10 less than or equal to V less than or equal to 60 mV a linear voltage dependence of noise power has been registered, while at V less than or equal to 5 mV a noticeable noise rise has been observed. The latter...

  12. 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.

  13. Laminin 332 in junctional epidermolysis bullosa.

    Science.gov (United States)

    Kiritsi, Dimitra; Has, Cristina; Bruckner-Tuderman, Leena

    2013-01-01

    Laminin 332 is an essential component of the dermal-epidermal junction, a highly specialized basement membrane zone that attaches the epidermis to the dermis and thereby provides skin integrity and resistance to external mechanical forces. Mutations in the LAMA3, LAMB3 and LAMC2 genes that encode the three constituent polypeptide chains, α3, β3 and γ2, abrogate or perturb the functions of laminin 332. The phenotypic consequences are diminished dermal-epidermal adhesion and, as clinical symptoms, skin fragility and mechanically induced blistering. The disorder is designated as junctional epidermolysis bullosa (JEB). This article delineates the signs and symptoms of the different forms of JEB, the mutational spectrum, genotype-phenotype correlations as well as perspectives for future molecular therapies. PMID:23076207

  14. Gastroesophageal junction adenocarcinoma. A case report

    Directory of Open Access Journals (Sweden)

    Marcos Félix Osorio Pagola

    2010-12-01

    Full Text Available The case of a 68 years old patient, smoking since adolescence, with urban origins, obesity history and gastroesophageal reflux symptoms is presented. The patient was diagnosed with gastroesophageal junction adenocarcinoma type III in the Gastroenterology Department of the Provincial University Hospital of Cienfuegos where he arrived with weight loss of about 20 pounds in four months along with dyspeptic manifestations such as stomach acidity, slow digestion, bloating and epigastric pain unrelated to food consumption. No dysphagia was observed as presentation form of the disease. The patient underwent surgery and chemotherapy and has had a favourable outcome up until today. It was decided to publish this article because of the few cases of gastroesophageal junction adenocarcinoma and especially type III that are commonly presented and also because the diagnosis is, unlike this case, usually made at an advanced stage of the disease

  15. Interface composition in magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Schad, R.; Mayen, K.; McCord, J.; Allen, D.; Yang, D.; Tondra, M.; Wang, D.

    2001-06-01

    The magnetoresistance of magnetic tunnel junctions critically depends on the exact composition at the interfaces. As such the completeness of the oxidation process of the Al layer (used to produce Al{sub 2}O{sub 3}-based tunnel junctions) plays an essential role in the magnetoresistance. We studied the chemical properties of ferromagnet/Al{sub 2}O{sub 3} interfaces as a function of original Al layer thickness. We have studied the concentrations of elementary and oxidized Al, Co, Ni, and Fe for varying roughness of the ferromagnetic layer. The oxidation process critically depends on the roughness of the underlying ferromagnetic (FM) layer. Al layers grown onto smooth FM layers oxidize homogeneously whereas Al layers grown on rough FM layers show a complicated oxidation behavior. Within the sensitivity of the analysis technique, we did not observe oxidation of the ferromagnetic layers, even for the overoxidized part of the samples. {copyright} 2001 American Institute of Physics.

  16. Interface composition in magnetic tunnel junctions

    Science.gov (United States)

    Schad, R.; Mayen, K.; McCord, J.; Allen, D.; Yang, D.; Tondra, M.; Wang, D.

    2001-06-01

    The magnetoresistance of magnetic tunnel junctions critically depends on the exact composition at the interfaces. As such the completeness of the oxidation process of the Al layer (used to produce Al2O3-based tunnel junctions) plays an essential role in the magnetoresistance. We studied the chemical properties of ferromagnet/Al2O3 interfaces as a function of original Al layer thickness. We have studied the concentrations of elementary and oxidized Al, Co, Ni, and Fe for varying roughness of the ferromagnetic layer. The oxidation process critically depends on the roughness of the underlying ferromagnetic (FM) layer. Al layers grown onto smooth FM layers oxidize homogeneously whereas Al layers grown on rough FM layers show a complicated oxidation behavior. Within the sensitivity of the analysis technique, we did not observe oxidation of the ferromagnetic layers, even for the overoxidized part of the samples.

  17. Strongly Correlated Fractional Quantum Hall Line Junctions

    OpenAIRE

    Zuelicke, U.; Shimshoni, E.

    2002-01-01

    We have studied a clean finite-length line junction between interacting counterpropagating single-branch fractional-quantum-Hall edge channels. Exact solutions for low-lying excitations and transport properties are obtained when the two edges belong to quantum Hall systems with different filling factors and interact via the long-range Coulomb interaction. Charging effects due to the coupling to external edge-channel leads are fully taken into account. Conductances and power laws in the curren...

  18. Laminin 332 in junctional epidermolysis bullosa

    OpenAIRE

    Kiritsi, Dimitra; Has, Cristina; Bruckner-Tuderman, Leena

    2013-01-01

    Laminin 332 is an essential component of the dermal-epidermal junction, a highly specialized basement membrane zone that attaches the epidermis to the dermis and thereby provides skin integrity and resistance to external mechanical forces. Mutations in the LAMA3, LAMB3 and LAMC2 genes that encode the three constituent polypeptide chains, α3, β3 and γ2, abrogate or perturb the functions of laminin 332. The phenotypic consequences are diminished dermal-epidermal adhesion and, as clinical sympto...

  19. Electron irradiation of tandem junction solar cells

    Science.gov (United States)

    Anspaugh, B. E.; Miyahira, T. F.; Scott-Monck, J. A.

    1979-01-01

    The electrical behavior of 100 micron thick tandem junction solar cells manufactured by Texas Instruments was studied as a function of 1 MeV electron fluence, photon irradiation, and 60 C annealing. These cells are found to degrade rapidly with radiation, the most serious loss occurring in the blue end of the cell's spectral response. No photon degradation was found to occur, but the cells did anneal a small amount at 60 C.

  20. 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

  1. The emerging diversity of neuromuscular junction disorders

    OpenAIRE

    Newsom-Davis, J

    2007-01-01

    Research advances over the last 30 years have shown that key transmembrane proteins at the neuromuscular junction are vulnerable to antibody-mediated autoimmune attack These targets are acetylcholine receptors (AChRs) and muscle specific kinase (MuSK) in myasthenia gravis, voltage-gated calcium channels (VGCCs) in the Lambert-Eaton myasthenic syndrome (LEMS), and voltage-gated potassium channels (VGKCs) in neuromyotonia. In parallel with these immunological advances, mutations identified in g...

  2. 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...... to the power law with the exponent of either 0.25 or 0.5 depending on the temperature variation in the critical current density....

  3. Gastroesophageal junction adenocarcinoma. A case report

    OpenAIRE

    Marcos Félix Osorio Pagola; Jesús Iván Gonzalez Batista; Nelia Maria Quintana Garcia

    2010-01-01

    The case of a 68 years old patient, smoking since adolescence, with urban origins, obesity history and gastroesophageal reflux symptoms is presented. The patient was diagnosed with gastroesophageal junction adenocarcinoma type III in the Gastroenterology Department of the Provincial University Hospital of Cienfuegos where he arrived with weight loss of about 20 pounds in four months along with dyspeptic manifestations such as stomach acidity, slow digestion, bloating and epigastric pain unrel...

  4. Nonlinearity in superconductivity and Josephson junctions

    International Nuclear Information System (INIS)

    Within the framework of the Bardeen, Cooper and Schrieffers (BCS) theory, the influence of anisotropy on superconducting states are investigated. Crystal anisotropy exists in un-conventional low temperature superconductors as e.g. U1-xThxBe13 and in high temperature superconductors. Starting from a phenomenological pairing interaction of the electrons or holes, the BCS approach is used to derive a set of coupled nonlinear algebraic equations for the momentum dependent gap parameter. The emphasis is put on bifurcation phenomena between s-, d-wave and mixed s- and d-wave symmetry and the influence on measurable quantities as the electron specific heat, spin susceptibility and Josephson tunnelling. Pitch-fork and perturbed pitch-fork bifurcations have been found separating s- and d-wave superconducting states from mixed s- and d-wave states. The additional superconducting states give rise to jumps in the electron specific heat below the transition temperature. These jumps are rounded in the case of perturbed pitch-fork bifurcations. An experiment to measure the sign of the interlayer interaction using dc SQUIDS is suggested. The Ambegaokar-Baratoff formalism has been used for calculating the quasiparticle current and the two phase coherent tunnelling currents in a Josephson junction made of anisotropic superconductors. It is shown that anisotropy can lead to a reduction in the product of the normal resistance and the critical current. For low voltages across the junction the usual resistively shunted Josephson model can be used. Finally, bunching in long circular Josephson junctions and suppression of chaos in point junctions have been investigated. (au) 113 refs

  5. Resonant inelastic tunneling in molecular junctions

    OpenAIRE

    Galperin, Michael; Nitzan, Abraham; Ratner, Mark A.

    2005-01-01

    Within a phonon-assisted resonance level model we develop a self-consistent procedure for calculating electron transport currents in molecular junctions with intermediate to strong electron-phonon interaction. The scheme takes into account the mutual influence of the electron and phonon subsystems. It is based on the 2nd order cumulant expansion, used to express the correlation function of the phonon shift generator in terms of the phonon momentum Green function. Equation of motion (EOM) meth...

  6. 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.

  7. 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.

  8. 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. PMID:25253865

  9. 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.

  10. Fluctuations of the peak current of tunnel diodes in multi-junction solar cells

    International Nuclear Information System (INIS)

    Interband tunnel diodes are widely used to electrically interconnect the individual subcells in multi-junction solar cells. Tunnel diodes have to operate at high current densities and low voltages, especially when used in concentrator solar cells. They represent one of the most critical elements of multi-junction solar cells and the fluctuations of the peak current in the diodes have an essential impact on the performance and reliability of the devices. Recently we have found that GaAs tunnel diodes exhibit extremely high peak currents that can be explained by resonant tunnelling through defects homogeneously distributed in the junction. Experiments evidence rather large fluctuations of the peak current in the diodes fabricated from the same wafer. It is a challenging task to clarify the reason for such large fluctuations in order to improve the performance of the multi-junction solar cells. In this work we show that the large fluctuations of the peak current in tunnel diodes can be caused by relatively small fluctuations of the dopant concentration. We also show that the fluctuations of the peak current become smaller for deeper energy levels of the defects responsible for the resonant tunnelling.

  11. 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.

  12. Tight junctions in Hailey-Hailey and Darier’s diseases

    OpenAIRE

    Laura Raiko; Pekka Leinonen; Päivi Hägg; Juha Peltonen; Aarne Oikarinen; Sirkku Peltonen

    2009-01-01

    Hailey-Hailey disease (HHD) and Darier's disease (DD) are caused by mutations in Ca2+-ATPases with the end result of desmosomal disruption and suprabasal acantholysis. Tight junctions (TJ) are located in the granular cell layer in normal skin and contribute to the epidermal barrier. Aberrations in the epidermal differentiation, such as in psoriasis, have been shown to lead to changes in the expression of TJ components. Our aim was to elucidate the expression and dynamics of the TJ proteins du...

  13. Numerical study for electromagnetic wave emission from intrinsic Josephson junction stacks with a dielectric cover

    Science.gov (United States)

    Koyama, T.; Matsumoto, H.; Ota, Y.; Machida, M.

    2013-08-01

    Electromagnetic (EM) wave emission from the intrinsic Josephson junction stacks (IJJ’s) covered with a thin dielectric medium is numerically investigated, using the multi-scale simulation method developed in our previous paper. It is shown that the power of emitted EM waves is considerably increased in the IJJ’s with a dielectric cover. The emission from the n = 2 resonance mode is greatly enhanced. The enhancement is caused by the excitation of a solitonic mode.

  14. 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

  15. 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

  16. 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

  17. 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

  18. ALS as a distal axonopathy : molecular mechanisms affecting neuromuscular junction stability in the presymptomatic stages of the disease

    NARCIS (Netherlands)

    Moloney, Elizabeth B; de Winter, Fred; Verhaagen, J.

    2014-01-01

    Amyotrophic Lateral Sclerosis (ALS) is being redefined as a distal axonopathy, in that many molecular changes influencing motor neuron degeneration occur at the neuromuscular junction (NMJ) at very early stages of the disease prior to symptom onset. A huge variety of genetic and environmental causes

  19. 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.

  20. Coulomb blockade in turnstile with multiple tunnel junctions

    CERN Document Server

    Lee, S C; Kang, D S; Kim, D C; Choi, C K; Ryu, J Y

    1999-01-01

    On the basis of the analytic solutions to the electrostatic problem of the multi-grated-small-junction systems, the stable domain for the Coulomb blockade of turnstile with multiple tunnel junctions at zero temperature has been analyzed as a function of the number of tunnel junction, the ratio of the gate capacitance to the junction capacitance, and the asymmetric factor. Our results show that domains form various shaped regions according to the asymmetric factor and their size depends on the number of junction and the ratio of the gate capacitance to the junction capacitance. In particular, it is shown that electrons can be transferred in positive and/or negative bias voltage depending on the asymmetric factor when an appropriate gate cycle is applied. Thus, the asymmetric factor plays an important role in determining the turnstile operation.

  1. Coherent diffraction of thermal currents in long Josephson tunnel junctions

    Science.gov (United States)

    Guarcello, Claudio; Giazotto, Francesco; Solinas, Paolo

    2016-08-01

    We discuss heat transport in thermally-biased long Josephson tunnel junctions in the presence of an in-plane magnetic field. In full analogy with the Josephson critical current, the phase-dependent component of the heat current through the junction displays coherent diffraction. Thermal transport is analyzed as a function of both the length and the damping of the junction, highlighting deviations from the standard "Fraunhofer" pattern characteristic of short junctions. The heat current diffraction patterns show features strongly related to the formation and penetration of Josephson vortices, i.e., solitons. We show that a dynamical treatment of the system is crucial for the realistic description of the Josephson junction, and it leads to peculiar results. In fact, hysteretic behaviors in the diffraction patterns when the field is swept up and down are observed, corresponding to the trapping of vortices in the junction.

  2. LRP4 is critical for neuromuscular junction maintenance.

    Science.gov (United States)

    Barik, Arnab; Lu, Yisheng; Sathyamurthy, Anupama; Bowman, Andrew; Shen, Chengyong; Li, Lei; Xiong, Wen-cheng; Mei, Lin

    2014-10-15

    The neuromuscular junction (NMJ) is a synapse between motor neurons and skeletal muscle fibers, and is critical for control of muscle contraction. Its formation requires neuronal agrin that acts by binding to LRP4 to stimulate MuSK. Mutations have been identified in agrin, MuSK, and LRP4 in patients with congenital myasthenic syndrome, and patients with myasthenia gravis develop antibodies against agrin, LRP4, and MuSK. However, it remains unclear whether the agrin signaling pathway is critical for NMJ maintenance because null mutation of any of the three genes is perinatal lethal. In this study, we generated imKO mice, a mutant strain whose LRP4 gene can be deleted in muscles by doxycycline (Dox) treatment. Ablation of the LRP4 gene in adult muscle enabled studies of its role in NMJ maintenance. We demonstrate that Dox treatment of P30 mice reduced muscle strength and compound muscle action potentials. AChR clusters became fragmented with diminished junctional folds and synaptic vesicles. The amplitude and frequency of miniature endplate potentials were reduced, indicating impaired neuromuscular transmission and providing cellular mechanisms of adult LRP4 deficiency. We showed that LRP4 ablation led to the loss of synaptic agrin and the 90 kDa fragments, which occurred ahead of other prejunctional and postjunctional components, suggesting that LRP4 may regulate the stability of synaptic agrin. These observations demonstrate that LRP4 is essential for maintaining the structural and functional integrity of the NMJ and that loss of muscle LRP4 in adulthood alone is sufficient to cause myasthenic symptoms. PMID:25319686

  3. Time domain analysis of dynamical switching in a Josephson junction

    OpenAIRE

    Sjostrand, Joachim; Walter, Jochen; Haviland, David; Hansson, Hans; Karlhede, Anders

    2004-01-01

    We have studied the switching behaviour of a small capacitance Josephson junction both in experiment, and by numerical simulation of a model circuit. The switching is a comples process involving the transition between two dynamical states of the non-linear circuit, arising from a frequency dependent damping of the Josephson junction. We show how a specific type of bias pulse-and-hold, can result in a fast detection of switching, even when the measurement bandwidth of the junction voltage is s...

  4. Macroscopic quantum effects in intrinsic Josephson junction stacks

    Science.gov (United States)

    Koyama, T.; Machida, M.

    2008-09-01

    A macroscopic quantum theory for the capacitively-coupled intrinsic Josephson junctions (IJJ’s) is constructed. We clarify the multi-junction effect for the macroscopic quantum tunneling (MQT) to the first resistive branch. It is shown that the escape rate is greatly enhanced by the capacitive coupling between junctions. We also discuss the origin of the N2-enhancement in the escape rate observed in the uniformly switching in Bi-2212 IJJ’s.

  5. 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.

  6. 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...

  7. F-theory Description of 3-String Junction

    OpenAIRE

    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 an unifying description of both string and string junction, and is advantageous over the M-theory picture of them.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Differences between liver gap junction protein and lens MIP 26 from rat: implications for tissue specificity of gap junctions.

    Science.gov (United States)

    Nicholson, B J; Takemoto, L J; Hunkapiller, M W; Hood, L E; Revel, J P

    1983-03-01

    Liver gap junctions and gap-junction-like structures from eye lenses are each comprised of a single major protein (Mr 28,000 and 26,000, respectively). These proteins display different two-dimensional peptide fingerprints, distinct amino acid compositions, nonhomologous N-terminal amino acid sequences and different sensitivities to proteases when part of the intact junction. However, the junctional protein of each tissue is well conserved between species, as demonstrated previously for lens and now for liver in several mammalian species. The possiblity of tissue-specific gap junction proteins is discussed in the light of data suggesting that rat heart gap junctions are comprised of yet a third protein. PMID:6299583

  14. 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...

  15. Atrioventricular Junction Ablation for Atrial Fibrillation.

    Science.gov (United States)

    Patel, Dilesh; Daoud, Emile G

    2016-04-01

    Atrioventricular junction (AVJ) ablation is an effective therapy in patients with symptomatic atrial fibrillation who are intolerant to or unsuccessfully managed with rhythm control or medical rate control strategies. A drawback is that the procedure mandates a pacing system. Overall, the safety and efficacy of AVJ ablation is high with a majority of the patients reporting significant improvement in symptoms and quality-of-life measures. Risk of sudden cardiac death after device implantation is low, especially with an appropriate postprocedure pacing rate. Mortality benefit with AVJ ablation has been shown in patients with heart failure and cardiac resynchronization therapy devices. PMID:26968669

  16. Phonon interference effects in molecular junctions

    International Nuclear Information System (INIS)

    We study coherent phonon transport through organic, π-conjugated molecules. Using first principles calculations and Green's function methods, we find that the phonon transmission function in cross-conjugated molecules, like meta-connected benzene, exhibits destructive quantum interference features very analogous to those observed theoretically and experimentally for electron transport in similar molecules. The destructive interference features observed in four different cross-conjugated molecules significantly reduce the thermal conductance with respect to linear conjugated analogues. Such control of the thermal conductance by chemical modifications could be important for thermoelectric applications of molecular junctions

  17. Phonon interference effects in molecular junctions

    Energy Technology Data Exchange (ETDEWEB)

    Markussen, Troels, E-mail: troels.markussen@gmail.com [Center for Atomic-scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2013-12-28

    We study coherent phonon transport through organic, π-conjugated molecules. Using first principles calculations and Green's function methods, we find that the phonon transmission function in cross-conjugated molecules, like meta-connected benzene, exhibits destructive quantum interference features very analogous to those observed theoretically and experimentally for electron transport in similar molecules. The destructive interference features observed in four different cross-conjugated molecules significantly reduce the thermal conductance with respect to linear conjugated analogues. Such control of the thermal conductance by chemical modifications could be important for thermoelectric applications of molecular junctions.

  18. Pseudospin dynamics in multimode polaritonic Josephson junctions

    Science.gov (United States)

    Pavlovic, G.; Malpuech, G.; Shelykh, I. A.

    2013-03-01

    Using Keldysh-Green function formalism we theoretically analyzed the dynamics of multimode exciton-polariton Josephson junctions. We took into account the spinor nature of polaritons and considered in detail the role of coupling of the fundamental modes with excited states. We demonstrate that the coupling to the reservoir results in a change of the oscillation pattern. In particular, it can lead to renormalization of the oscillation frequency, appearance of higher order harmonics, and induce transition between the regimes of free Josephson oscillations and macroscopic quantum self-trapping.

  19. Kink motion in a curved Josephson junction

    DEFF Research Database (Denmark)

    Sørensen, Mads Peter

    The sine-Gordon equation is one of the three classical nonlinear partial differential equations possessing soliton solutions in the case of one spatial dimension. Extending the sine-Gordon equation to two spatial dimensions is relevant for applications to the dynamics of large area Josephson...... junctions. In particular we have investigated Josephson waveguides consisting of two rectangular large area regions joined by a bent section of constant curvature. Transverse homogeneous and inhomogeneous Neumann boundary conditions are used. Numerical and approximate analytical tools have been used...

  20. 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…

  1. 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.

  2. 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...

  3. Effects of Total Ionizing Dose on Bipolar Junction Transistor

    Directory of Open Access Journals (Sweden)

    Chee F. Pien

    2010-01-01

    Full Text Available Problem statement: The amount of ionizing radiation that Bipolar Junction Transistor (BJT devices encounter during their lifecycle degrades both of their functional and electrical parameter performances. The different radiation environments either in space, high energy physics experiments, nuclear environment or fabrication process as well as for standard terrestrial operation possess an impact on the devices. Approach: In this research, analytical studies of the effects of ionizing radiation introduced in Commercial-Off-The Shelf (COTS NPN BJTs by 60Co gamma (γ rays had been performed. Results: It was observed that exposure of BJTs to 60Co caused ionizing radiation damage. Ionizing radiation damage was caused mainly by excess charges trapped on or near the surfaces of their insulating layers and interfaces. This phenomenon reduced the minority carrier lifetime and thus, leading to a decrease in the current gain of the BJTs. Conclusion: This ionizing radiation effect was found to arouse either a permanent or temporarily damage in the devices depending on their current drives and also the Total Ionizing Dose (TID absorbed. The performance and degradation of selected BJT devices during irradiation with respect to total dose 60Co were presented in this study.

  4. DICER Regulates the Formation and Maintenance of Cell-Cell Junctions in the Mouse Seminiferous Epithelium.

    Science.gov (United States)

    Korhonen, Hanna Maria; Yadav, Ram Prakash; Da Ros, Matteo; Chalmel, Frédéric; Zimmermann, Céline; Toppari, Jorma; Nef, Serge; Kotaja, Noora

    2015-12-01

    The endonuclease DICER that processes micro-RNAs and small interfering RNAs is essential for normal spermatogenesis and male fertility. We previously showed that the deletion of Dicer1 gene in postnatal spermatogonia in mice using Ngn3 promoter-driven Cre expression caused severe defects in the morphogenesis of haploid spermatid to mature spermatozoon, including problems in cell polarization and nuclear elongation. In this study, we further analyzed the same mouse model and revealed that absence of functional DICER in differentiating male germ cells induces disorganization of the cell-cell junctions in the seminiferous epithelium. We detected discontinuous and irregular apical ectoplasmic specializations between elongating spermatids and Sertoli cells. The defective anchoring of spermatids to Sertoli cells caused a premature release of spermatids into the lumen. Our findings may help also explain the abnormal elongation process of remaining spermatids because these junctions and the correct positioning of germ cells in the epithelium are critically important for the progression of spermiogenesis. Interestingly, cell adhesion-related genes were generally upregulated in Dicer1 knockout germ cells. Claudin 5 ( Cldn5 ) was among the most upregulated genes and we show that the polarized localization of CLAUDIN5 in the apical ectoplasmic specializations was lost in Dicer1 knockout spermatids. Our results suggest that DICER-dependent pathways control the formation and organization of cell-cell junctions in the seminiferous epithelium via the regulation of cell adhesion-related genes. PMID:26510868

  5. 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.

  6. 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.

  7. Fractional Solitons in Excitonic Josephson Junctions.

    Science.gov (United States)

    Hsu, Ya-Fen; Su, Jung-Jung

    2015-01-01

    The Josephson effect is especially appealing to physicists because it reveals macroscopically the quantum order and phase. In excitonic bilayers the effect is even subtler due to the counterflow of supercurrent as well as the tunneling between layers (interlayer tunneling). Here we study, in a quantum Hall bilayer, the excitonic Josephson junction: a conjunct of two exciton condensates with a relative phase ϕ0 applied. The system is mapped into a pseudospin ferromagnet then described numerically by the Landau-Lifshitz-Gilbert equation. In the presence of interlayer tunneling, we identify a family of fractional sine-Gordon solitons which resemble the static fractional Josephson vortices in the extended superconducting Josephson junctions. Each fractional soliton carries a topological charge Q that is not necessarily a half/full integer but can vary continuously. The calculated current-phase relation (CPR) shows that solitons with Q = ϕ0/2π is the lowest energy state starting from zero ϕ0 - until ϕ0 > π - then the alternative group of solitons with Q = ϕ0/2π - 1 takes place and switches the polarity of CPR. PMID:26511770

  8. Josephson current in parallel SFS junctions

    Science.gov (United States)

    Ioselevich, Pavel; Ostrovsky, Pavel; Fominov, Yakov; Feigelman, Mikhail

    We study a Josephson junction between superconductors connected by two parallel ferromagnetic arms. If the ferromagnets are fully polarised, supercurrent can only flow via Cooper pair splitting between the differently polarised arms. The disorder-average current is suppressed, but mesoscopic fluctuations lead to a significant typical current. We extract the typical current from a current-current correlator. The current is proportional to sin2 α / 2 , where α is the angle between the polarisations of the two arms, revealing the spin dependence of crossed Andreev reflection. Compared to an SNS device of the same geometry, the typical SFS current is small by a factor determined by the properties of the superconducting leads alone. The current is insensitive to the flux threading the area between the ferromagnetic arms of the junction. However, if the ferromagnetic arms are replaced by metal with magnetic impurities, or partially polarised ferromagnets, the Josephson current starts depending on the flux with a period of h / e , i.e. twice the superconducting flux quantum.

  9. Fabrication of Niobium Nanobridge Josephson Junctions

    Science.gov (United States)

    Tachiki, T.; Horiguchi, K.; Uchida, T.

    2014-05-01

    To realize antenna-coupled Josephson detectors for microwave and millimeter-wave radiation, planar-type Nb nanobridge Josephson junctions were fabricated. Nb thin films whose thickness, the root mean square roughness and the critical temperature were 20.0 nm, 0.109 nm and 8.4 K, respectively were deposited using a DC magnetron sputtering at a substrate temperature of 700°C. Nanobridges were obtained from the film using 80-kV electron beam lithography and reactive ion-beam etching in CF4 (90%) + O2 (10%) gases. The minimum bridge area was 65 nm wide and 60 nm long. For the nanobridge whose width and length were less than 110 nm, an I-V characteristic showed resistively-shunted-junction behaviour near the critical temperature. Moreover, Shapiro steps were observed in the nanobridge with microwave irradiation at a frequency of 6 - 30 GHz. The Nb nanobridges can be used as detectors in the antenna-coupled devices.

  10. 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.

  11. Functional ferroelectric tunnel junctions on silicon

    Science.gov (United States)

    Guo, Rui; Wang, Zhe; Zeng, Shengwei; Han, Kun; Huang, Lisen; Schlom, Darrell G.; Venkatesan, T.; Ariando; Chen, Jingsheng

    2015-07-01

    The quest for solid state non-volatility memory devices on silicon with high storage density, high speed, low power consumption has attracted intense research on new materials and novel device architectures. Although flash memory dominates in the non-volatile memory market currently, it has drawbacks, such as low operation speed, and limited cycle endurance, which prevents it from becoming the “universal memory”. In this report, we demonstrate ferroelectric tunnel junctions (Pt/BaTiO3/La0.67Sr0.33MnO3) epitaxially grown on silicon substrates. X-ray diffraction spectra and high resolution transmission electron microscope images prove the high epitaxial quality of the single crystal perovskite films grown on silicon. Furthermore, the write speed, data retention and fatigue properties of the device compare favorably with flash memories. The results prove that the silicon-based ferroelectric tunnel junction is a very promising candidate for application in future non-volatile memories.

  12. 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.

  13. 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.

  14. 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. PMID:27273333

  15. Fractional Solitons in Excitonic Josephson Junctions

    Science.gov (United States)

    Hsu, Ya-Fen; Su, Jung-Jung

    2015-10-01

    The Josephson effect is especially appealing to physicists because it reveals macroscopically the quantum order and phase. In excitonic bilayers the effect is even subtler due to the counterflow of supercurrent as well as the tunneling between layers (interlayer tunneling). Here we study, in a quantum Hall bilayer, the excitonic Josephson junction: a conjunct of two exciton condensates with a relative phase ϕ0 applied. The system is mapped into a pseudospin ferromagnet then described numerically by the Landau-Lifshitz-Gilbert equation. In the presence of interlayer tunneling, we identify a family of fractional sine-Gordon solitons which resemble the static fractional Josephson vortices in the extended superconducting Josephson junctions. Each fractional soliton carries a topological charge Q that is not necessarily a half/full integer but can vary continuously. The calculated current-phase relation (CPR) shows that solitons with Q = ϕ0/2π is the lowest energy state starting from zero ϕ0 - until ϕ0 > π - then the alternative group of solitons with Q = ϕ0/2π - 1 takes place and switches the polarity of CPR.

  16. Electrophysiological study in neuromuscular junction disorders.

    Science.gov (United States)

    Cherian, Ajith; Baheti, Neeraj N; Iype, Thomas

    2013-01-01

    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. PMID:23661960

  17. Intrinsic Josephson Junctions with Intermediate Damping

    Science.gov (United States)

    Warburton, Paul A.; Saleem, Sajid; Fenton, Jon C.; Speller, Susie; Grovenor, Chris R. M.

    2011-03-01

    In cuprate superconductors, adjacent cuprate double-planes are intrinsically Josephson-coupled. For bias currents perpendicular to the planes, the current-voltage characteristics correspond to those of an array of underdamped Josephson junctions. We will discuss our experiments on sub-micron Tl-2212 intrinsic Josephson junctions (IJJs). The dynamics of the IJJs at the plasma frequency are moderately damped (Q ~ 8). This results in a number of counter-intuitive observations, including both a suppression of the effect of thermal fluctuations and a shift of the skewness of the switching current distributions from negative to positive as the temperature is increased. Simulations confirm that these phenomena result from repeated phase slips as the IJJ switches from the zero-voltage to the running state. We further show that increased dissipation counter-intuitively increases the maximum supercurrent in the intermediate damping regime (PRL vol. 103, art. no. 217002). We discuss the role of environmental dissipation on the dynamics and describe experiments with on-chip lumped-element passive components in order control the environment seen by the IJJs. Work supported by EPSRC.

  18. 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.

  19. Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels.

    Science.gov (United States)

    Zhang, Yue; Yang, Wan-Xi

    2016-01-01

    Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens)) proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs. PMID:27335757

  20. Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels

    Science.gov (United States)

    Zhang, Yue

    2016-01-01

    Summary Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens)) proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs. PMID:27335757

  1. 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 calculated...

  2. Spin and valley transports in junctions of Dirac fermions

    International Nuclear Information System (INIS)

    We study spin and valley transports in junctions composed of silicene and topological crystalline insulators. We consider normal/magnetic/normal Dirac metal junctions where a gate electrode is attached to the magnetic region. In a normal/antiferromagnetic/normal silicene junction, we show that the current through this junction is valley and spin polarized due to the coupling between valley and spin degrees of freedom, and the valley and spin polarizations can be tuned by local application of a gate voltage. In particular, we find a fully valley and spin polarized current by applying the electric field. In a normal/ferromagnetic/normal topological crystalline insulator junction with a strain induced in the ferromagnetic segment, we investigate valley-resolved conductances and clarify how the valley polarization stemming from the strain and exchange field appears in this junction. It is found that by changing the direction of the magnetization and the potential in the ferromagnetic region, one can control the dominant valley contribution out of four valley degrees of freedom. We also review spin transport in normal/ferromagnetic/normal graphene junctions, and spin and valley transports in normal/ferromagnetic/normal silicene junctions for comparison. (paper)

  3. 75 FR 76294 - Radio Broadcasting Services: Pacific Junction, IA

    Science.gov (United States)

    2010-12-08

    ... Junction, in overcoming objections raised by the FAA to the activation of this allotment. See 75 FR 30756... 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...

  4. 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 dB) w...

  5. 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.

  6. 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.

  7. Activated Microglia do not form Functional Gap Junctions in vivo

    OpenAIRE

    Wasseff, Sameh K.; Scherer, Steven S.

    2014-01-01

    We investigated whether microglia form gap junctions with themselves, or with astrocytes, oligodendrocytes, or neurons in vivo in normal mouse brains, and in pathological conditions that induce microglial activation - brain injury, a model of Alzheimer’s disease. Although microglia are in close physical proximity to glia and neurons, they do not form functional gap junctions under these pathological conditions.

  8. Routing Trains Through Railway Junctions: A New Set Packing Approach

    DEFF Research Database (Denmark)

    Lusby, Richard; Larsen, Jesper; Ryan, David;

    The problem of routing trains through railway junctions is an integral part of railway operations. Large junctions are highly interconnected networks of track where multiple railway lines meet, intersect, and split. The number of possible routings makes this a very complicated problem. Here we show...

  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. Microwave phase locking of Josephson-junction fluxon oscillators

    DEFF Research Database (Denmark)

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

    1990-01-01

    Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two...

  11. Spatial dependence of plasma oscillations in Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Holst, Thorsten; Hansen, Jørn Bindslev

    1991-01-01

    We report on direct measurements of the plasma oscillations in Josephson tunnel junctions of various spatial dimensions. The effect of the spatial variation of the Cooper-pair phase difference (the Josephson phase) on the dynamics of the junction was investigated by application of a static magnet...

  12. Microwave dependence of subharmonic gap structure in superconducting junctions

    DEFF Research Database (Denmark)

    Sørensen, O. Hoffman; Kofoed, Bent; Pedersen, Niels Falsig;

    1974-01-01

    Experiments on both point-contact junctions (Nb-Nb) and on small area thin-film tunnel junctions (Sn-O-Sn) show that applied 4-mm radiation produces satellites associated with "subharmonic" gap structure as well as the familiar microwave-assisted tunneling structure associated with the supercondu...

  13. 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.

  14. 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...

  15. 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...

  16. 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

  17. Molecular Transport Junctions Created By Self-Contacting Gapped Nanowires.

    Science.gov (United States)

    Lim, Jong Kuk; Lee, One-Sun; Jang, Jae-Won; Petrosko, Sarah Hurst; Schatz, George C; Mirkin, Chad A

    2016-08-01

    Molecular transport junctions (MTJs) are important components in molecular electronic devices. However, the synthesis of MTJs remains a significant challenge, as the dimensions of the junction must be tailored for each experiment, based on the molecular lengths. A novel methodology is reported for forming MTJs, taking advantage of capillary and van der Waals forces. PMID:27364594

  18. Duodeno-jejunal junction dyssynergia: Description of a novel syndrome

    Institute of Scientific and Technical Information of China (English)

    Ahmed Shafik; Ismail A Shafik; Olfat El Sibai; Ali A Shafik

    2007-01-01

    AIM: To investigate the hypothesis that duodeno-jejunal dyssynergia existed at the duodeno-jejunal junction.METHODS: Of 112 patients who complained of epigastric distension and discomfort after meals, we encountered nine patients in whom the duodeno-jejunal junction did not open on duodenal contraction. Seven healthy volunteers were included in the study. A condom which was inserted into the 1st duodenum was filled up to 10 mL with saline in increments of 2 mL and pressure response to duodenal distension was recorded from the duodenum, duodeno-jejunal junction and the jejunum.RESULTS: In healthy volunteers, duodenal distension with 2 and 4 mL did not produce pressure changes,while 6 and up to 10 mL distension effected significant duodenal pressure increase, duodeno-jejunal junction pressure decrease but no jejunal pressure change. In patients, resting pressure and duodeno-jejunal junction and jejunal pressure response to 2 and 4 mL duodenal distension were similar to those of healthy volunteers.Six and up to 10 mL 1st duodenal distension produced significant duodenal and duodeno-jejunal junction pressure increase and no jejunal pressure change.CONCLUSION: Duodeno-jejunal junction failed to open on duodenal contraction, a condition we call 'duodeno-jejunal junction dyssynergia syndrome' which probably leads to stagnation of chyme in the duodenum and explains patients' manifestations.

  19. Shapiro and parametric resonances in coupled Josephson junctions

    OpenAIRE

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

    2012-01-01

    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.

  20. Shapiro and parametric resonances in coupled Josephson junctions

    International Nuclear Information System (INIS)

    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.

  1. Temperature dependence of charge transport in conjugated single molecule junctions

    Science.gov (United States)

    Huisman, Eek; Kamenetska, Masha; Venkataraman, Latha

    2011-03-01

    Over the last decade, the break junction technique using a scanning tunneling microscope geometry has proven to be an important tool to understand electron transport through single molecule junctions. Here, we use this technique to probe transport through junctions at temperatures ranging from 5K to 300K. We study three amine-terminated (-NH2) conjugated molecules: a benzene, a biphenyl and a terphenyl derivative. We find that amine groups bind selectively to undercoordinate gold atoms gold all the way down to 5K, yielding single molecule junctions with well-defined conductances. Furthermore, we find that the conductance of a single molecule junction increases with temperature and we present a mechanism for this temperature dependent transport result. Funded by a Rubicon Grant from The Netherlands Organisation for Scientific Research (NWO) and the NSEC program of NSF under grant # CHE-0641523.

  2. 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.

  3. Two coupled Josephson junctions: dc voltage controlled by biharmonic current

    International Nuclear Information System (INIS)

    We study transport properties of two Josephson junctions coupled by an external shunt resistance. One of the junctions (say, the first) is driven by an unbiased ac current consisting of two harmonics. The device can rectify the ac current yielding a dc voltage across the first junction. For some values of coupling strength, controlled by an external shunt resistance, a dc voltage across the second junction can be generated. By variation of system parameters such as the relative phase or frequency of two harmonics, one can conveniently manipulate both voltages with high efficiency, e.g. changing the dc voltages across the first and second junctions from positive to negative values and vice versa. (paper)

  4. Role of autophagy in the regulation of epithelial cell junctions.

    Science.gov (United States)

    Nighot, Prashant; Ma, Thomas

    2016-01-01

    Autophagy is a cell survival mechanism by which bulk cytoplasmic material, including soluble macromolecules and organelles, is targeted for lysosomal degradation. The role of autophagy in diverse cellular processes such as metabolic stress, neurodegeneration, cancer, aging, immunity, and inflammatory diseases is being increasingly recognized. Epithelial cell junctions play an integral role in the cell homeostasis via physical binding, regulating paracellular pathways, integrating extracellular cues into intracellular signaling, and cell-cell communication. Recent data indicates that cell junction composition is very dynamic. The junctional protein complexes are actively regulated in response to various intra- and extra-cellular clues by intracellular trafficking and degradation pathways. This review discusses the recent and emerging information on how autophagy regulates various epithelial cell junctions. The knowledge of autophagy regulation of epithelial junctions will provide further rationale for targeting autophagy in a wide variety of human disease conditions. PMID:27583189

  5. 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.

  6. 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.

  7. Quantum Tunneling Current in Nanoscale Plasmonic Junctions

    Science.gov (United States)

    Zhang, Peng; Lau, Y. Y.; Gilgenbach, R. M.

    2014-10-01

    Recently, electron tunneling between plasmonic resonators is found to support quantum plasmon resonances, which may introduce new regimes in nano-optoelectronics and nonlinear optics. This revelation is of substantial interest to the fundamental problem of electron transport in nano-scale, for example, in a metal-insulator-metal junction (MIM), which has been continuously studied for decades. Here, we present a self-consistent model of electron transport in a nano-scale MIM, by solving the coupled Schrödinger and Poisson equations. The effects of space charge, exchange-correlation, anode emission, and material properties of the electrodes and insulator are examined in detail. The self-consistent calculations are compared with the widely used Simmons formula. Transition from the direct tunneling regime to the space-charge-limited regime is demonstrated. This work was supported by AFOSR.

  8. 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.

  9. 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.

  10. 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.

  11. 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).

  12. 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.

  13. 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.

  14. 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.

  15. Work fluctuations in bosonic Josephson junctions

    Science.gov (United States)

    Lena, R. G.; Palma, G. M.; De Chiara, G.

    2016-05-01

    We calculate the first two moments and full probability distribution of the work performed on a system of bosonic particles in a two-mode Bose-Hubbard Hamiltonian when the self-interaction term is varied instantaneously or with a finite-time ramp. In the instantaneous case, we show how the irreversible work scales differently depending on whether the system is driven to the Josephson or Fock regime of the bosonic Josephson junction. In the finite-time case, we use optimal control techniques to substantially decrease the irreversible work to negligible values. Our analysis can be implemented in present-day experiments with ultracold atoms and we show how to relate the work statistics to that of the population imbalance of the two modes.

  16. Sandwich-type gated mechanical break junctions

    International Nuclear Information System (INIS)

    We introduce a new device architecture for the independent mechanical and electrostatic tuning of nanoscale charge transport. In contrast to previous gated mechanical break junctions with suspended source-drain electrodes, the devices presented here prevent an electromechanical tuning of the electrode gap by the gate. This significant improvement originates from a direct deposition of the source and the drain electrodes on the gate dielectric. The plasma-enhanced native oxide on the aluminum gate electrode enables measurements at gate voltages up to 1.8 V at cryogenic temperatures. Throughout the bending-controlled tuning of the source-drain distance, the electrical continuity of the gate electrode is maintained. A nanoscale island in the Coulomb blockade regime serves as a first experimental test system for the devices, in which the mechanical and electrical control of charge transport is demonstrated.

  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. 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.

  20. High Tc Josephson Junctions, SQUIDs and magnetometers

    International Nuclear Information System (INIS)

    There has recently been considerable progress in the state-of-the-art of high-Tc magnetometers based on dc SQUIDs (Superconducting Quantum Interference Devices). This progress is due partly to the development of more manufacturable Josephson junctions, making SQUIDs easier to fabricate, and partly to the development of multiturn flux transformers that convert the high sensitivity of SQUIDs to magnetic flux to a correspondingly high sensitivity to magnetic field. Needless to say, today's high-Tc SQUIDs are still considerably less sensitive than their low-Tc counterparts, particularly at low frequencies (f) where their level of 1/f noise remains high. Nonetheless, the performance of the high-Tc devices has now reached the point where they are adequate for a number of the less demanding applications; furthermore, as we shall see, at least modest improvements in performance are expected in the near future. In this article, the author outlines these various developments. This is far from a comprehensive review of the field, however, and, apart from Sec. 2, he describes largely his own work. He begins in Sec. 2 with an overview of the various types of Josephson junctions that have been investigated, and in Sec. 3, he describes some of the SQUIDs that have been tested, and assess their performance. Section 4 discuss the development of the multilayer structures essential for an interconnect technology, and, in particular, for crossovers and vias. Section 5 shows how this technology enables one to fabricate multiturn flux transformers which, in turn, can be coupled to SQUIDs to make magnetometers. The performance and possible future improvements in these magnetometers are assessed, and some applications mentioned

  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. 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.

  3. 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.

  4. 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.

  5. Gold plasmonic effects on charge transport through single molecule junctions

    Science.gov (United States)

    Adak, Olgun; Venkataraman, Latha

    2014-03-01

    We study the impact of surface plasmon polaritons, the coupling of electromagnetic waves to collective electron oscillations on metal surfaces, on the conductance of single-molecule junctions. We use a scanning-tunneling microscope based break junction setup that is built into an optical microscope to form molecular junctions. Coherent 685nm light is used to illuminate the molecular junctions formed with 4,4'-bipyridine with diffraction limited focusing performance. We employ a lock-in type technique to measure currents induced by light. Furthermore, the thermal expansion due to laser heating is mimicked by mechanically modulating inter-electrode separation. For each junction studied, we measure current, and use AC techniques to determine molecular junction resonance levels and coupling strengths. We use a cross correlations analysis technique to analyze and compare the effect of light to that of the mechanical modulation. Our results show that junction transmission characteristics are not altered under illumination, within the resolution of our instrument. We argue that photo-currents measured with lock-in techniques in these kinds of structures are due to thermal effects. This work was funded by the Center for Re-Defining Photovoltaic Efficiency through Molecule Scale Control, an EFRC funded by the US Department of Energy, Office of Basic Energy Sciences under Contract No. DESC0001085.

  6. 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.

  7. 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.

  8. Thin-film Josephson junctions with alternating critical current density

    Science.gov (United States)

    Moshe, Maayan; Kogan, V. G.; Mints, R. G.

    2009-01-01

    We study the field dependence of the maximum current Im(H) in narrow edge-type thin-film Josephson junctions with alternating critical current density. Im(H) is evaluated within nonlocal Josephson electrodynamics taking into account the stray fields that affect the difference of the order-parameter phases across the junction and therefore the tunneling currents. We find that the phase difference along the junction is proportional to the applied field, depends on the junction geometry, but is independent of the Josephson critical current density gc , i.e., it is universal. An explicit form for this universal function is derived for small currents through junctions of the width W≪Λ , the Pearl length. The result is used to calculate Im(H) . It is shown that the maxima of Im(H)∝1/H and the zeros of Im(H) are equidistant but only in high fields. We find that the spacing between zeros is proportional to 1/W2 . The general approach is applied to calculate Im(H) for a superconducting quantum interference device with two narrow edge-type junctions. If gc changes sign periodically or randomly, as it does in grain boundaries of high- Tc materials and superconductor-ferromagnet-superconductor heterostructures, Im(H) not only acquires the major side peaks, but due to nonlocality the following peaks decay much slower than in bulk junctions.

  9. 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.

  10. 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.

  11. 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

  12. Robustness of SuperJunction structures against cosmic ray induced breakdown

    Science.gov (United States)

    Antoniou, Marina; Udrea, Florin; Bauer, Friedhelm

    2010-04-01

    In this paper we present a new design approach which dramatically improves the robustness of power semiconductor device against cosmic rays induced breakdown. This failure mode occurs during continuous operation at a DC rail voltage, which in practice is well below the breakdown rating (typically half of the breakdown). This failure is more prominent for higher breakdown rated devices (above 2 kV) and represents one of the main causes of concern, especially if the power systems are operated at higher altitude. Using a mathematical model for the calculation of the cosmic ray breakdown failure rate proposed by Zeller [1], we show that by employing a SuperJunction structure in the drift region of a high voltage diode we can achieve a great improvement in the robustness of the device against cosmic ray radiation. Since the cosmic ray failure rate is strongly dependent on the electric field distribution, the two-dimensional nature of the SuperJunction electric field with lower peaks and more even distribution offers a huge advantage over the use of standard PiN devices. Finally, a physical two-dimensional electric field model for the SuperJunction structures is developed which is then imported into Zeller's model to compute the cosmic ray failure rate for different DC voltage rails.

  13. 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.

  14. 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.

  15. Ballistic conductivity of graphene channel with p-n junction at ferroelectric domain wall

    Science.gov (United States)

    Morozovska, Anna N.; Eliseev, Eugene A.; Strikha, Maksym V.

    2016-06-01

    The influence of a ferroelectric domain wall on the ballistic conductance of a single-layer graphene channel in the graphene/physical gap/ferroelectric film heterostructure has been studied in the Wentzel-Kramers-Brillouin approximation. The self-consistent numerical simulation of the electric field and the space charge dynamics in the heterostructure, as well as the approximate analytical theory, show that the contact between the domain wall and the surface creates a p-n junction in the graphene channel. We calculated that the carrier concentration induced in graphene by uncompensated ferroelectric dipoles originated from the abrupt spontaneous polarization change near the surface can reach values of about 1019 m-2, which are two orders of magnitude higher than those obtained for the graphene on non-ferroelectric substrates. Therefore, we predict that the graphene channel with the p-n junction caused by the ferroelectric domain wall would be characterized by rather a high ballistic conductivity. Moreover, the graphene p-n junction at the ferroelectric domain wall can be an excellent rectifier with a conductivity ratio of about 10 between the direct and reverse polarities of the applied voltage.

  16. 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

  17. 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

  18. 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.

  19. 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'.

  20. 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”.

  1. Magnetic interaction between spatially extended superconducting tunnel junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    2002-01-01

    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......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...

  2. 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.

  3. 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...

  4. 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 mathematical discussion makes use of the phase-space representation of the solutions to the differential equation. The behavior of the trajectories in phase space is described for different characteristic regions in parameter space and the associated features of the junction IV curve to be...... expected are pointed out. The main objective is to provide a qualitative understanding of the junction behavior, to clarify which kinds of properties may be derived from the shunted-junction model, and to specify the relative arrangement of the important domains in the parameter-space decomposition....

  5. 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...... that have become nervefree. Furthermore we show that epithelial cells are unable to exchange low-molecular weight fluorescent dyes....

  6. 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.)

  7. Bilayer graphene Hall bar with a pn-junction

    OpenAIRE

    Milovanovic, S. P.; Masir, M. Ramezani; Peeters, F. M.

    2013-01-01

    We investigate the magnetic field dependence of the Hall and the bend resistances for a ballistic Hall bar structure containing a pn-junction sculptured from a bilayer of graphene. The electric response is obtained using the billiard model and we investigate the cases of bilayer graphene with and without a band gap. Two different conduction regimes are possible: $i$) both sides of the junction have the same carrier type, and $ii$) one side of the junction is n-type while the other one is p-ty...

  8. 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.

  9. Effects of formaldehyde inhalation on the junctional proteins of nasal respiratory mucosa of rats.

    Science.gov (United States)

    Arican, R Yavuz; Sahin, Zeliha; Ustunel, Ismail; Sarikcioglu, Levent; Ozdem, Sadi; Oguz, Nurettin

    2009-07-01

    Exposure to formaldehyde, which is an organic compound, disturbs the integrity of nasal mucosa. In this study, we aimed to clarify the protein changes in the junctional complex of nasal mucosa of Wistar rats exposed to formaldehyde inhalation. The study was performed in 20 female Wistar rats. Rats were divided into two groups randomly. Control rats were allowed free access to standard rat chaw and tap water (n:10). Experimental group was exposed to formaldehyde vapor at 15ppm, 6h/day, 5 days/week for 12 weeks (n:10). Histological evaluation of the experimental model was determined by hematoxylin-eosin (HE) and periodic acid Schiff (PAS) stainings of paraffin-embedded nasal mucosa tissues and by electron microscopy. The effects of formaldehyde inhalation on the distribution of occludin, E-cadherin, and gamma-catenin were assessed by immunohistochemistry. The nasal mucosa of the experimental group was correlated with hypertrophy in goblet cell, degeneration in basal lamina, stratification of epithelium, and proliferation. Thickness of basal lamina and also local degenerative regions, vacuole increase in cytoplasmic areas, irregular forms of kinocilium and loss of sharpness in the kinocilium membrane were the findings at the ultrastructural level. The expressions of E-cadherin, occludin, gamma-catenin proteins in intercellular junctional complexes of rat nasal mucosa were also decreased in experimental group compared to control group. The findings of the present study indicated that formaldehyde vapor inhalation in the concentrations and duration of exposure used in the present experiment significantly decreased the density of structural proteins of the junctional complex in the nasoepithelium. It was suggested that, the formaldehyde inhalation could cause complete impairment of intercellular junctional complexes and disturb the tissue integrity in nasal mucosa at higher concentrations. PMID:18996001

  10. Anterior Overgrowth in Primary Curves, Compensatory Curves and Junctional Segments in Adolescent Idiopathic Scoliosis

    Science.gov (United States)

    van Stralen, Marijn; Chu, Winnie C. W.; Lam, Tsz-Ping; Ng, Bobby K. W.; Vincken, Koen L.; Cheng, Jack C. Y.; Castelein, René M.

    2016-01-01

    Introduction Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before. Methods A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98–1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between. Results The anterior-posterior difference of spinal length, based on “true” anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; Plumbar lordosis (+7.8%; Plumbar curves). Conclusions Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is confined to the primary as well as the compensatory curves, the junctional zones do not exhibit this growth discrepancy, however, they are straight. PMID:27467745

  11. Severe Spinal Cord Injury Causes Immediate Multi-cellular Dysfunction at the Chondro-Osseous Junction

    OpenAIRE

    Morse, Leslie R; XU, Yan(Department of Music,Guangxi Normal University); Solomon, Bethlehem; Boyle, Lara; Yoganathan, Subbiah; Stashenko, Philip; Battaglino, Ricardo A.

    2011-01-01

    Spinal cord injury is associated with rapid bone loss and arrested long bone growth due to mechanisms that are poorly understood. In this study, we sought to determine the effects of severe T10 contusion spinal cord injury on the sublesional bone microenvironment in adolescent rats. A severe lower thoracic (vertebral T10) spinal cord injury was generated by weight drop (10 g×50 mm). Severely injured and body weight-matched uninjured male Sprague–Dawley rats were studied. At 3 and 5 days post-...

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

    2013-09-01

    We study the temperature dependence of the critical current modulation Ic(H) for two types of planar Josephson junctions: a low-Tc Nb/CuNi/Nb and a high-Tc YBa2Cu3O7-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 Ic(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.

  17. 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 polarity...

  18. Polymer light-emitting electrochemical cells with frozen junctions

    Science.gov (United States)

    Gao, Jun; Li, Yongfang; Yu, Gang; Heeger, Alan J.

    1999-10-01

    We report on polymer light-emitting electrochemical cells (LECs) with frozen p-i-n junctions. The dynamic p-i-n junction in polymer LECs is stabilized by lowering the temperature below the glass transition temperature of the ion-transport polymer. Detailed studies have shown that the frozen p-i-n junction in LECs based on the luminescent polymer poly[5-(2'ethylhexyloxy)-2-methoxy-1,4-phenylene vinylene] and polyethylene oxide containing lithium triflate (PEO:LiCF3SO3) is stable at temperatures up to 200 K. Frozen-junction LECs offer a number of advantages; they exhibit unipolar light emission, balanced injection, fast response, high brightness, low operating voltage, and insensitivity to electrode materials and film thickness.

  19. 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.

  20. Current–voltage characteristics of triple-barrier Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    De Luca, R., E-mail: rdeluca@unisa.it; Giordano, A.

    2015-06-15

    Highlights: • I–V characteristics of triple-barrier Josephson junctions (TBJJs) are studied. • The I–V characteristics are identical to those of an ordinary single-barrier Josephson junction. • In the presence of r. f. radiation integer and fractional Shapiro steps appear. - Abstract: Current–voltage characteristics of triple-barrier Josephson junctions are analytically and numerically studied. In the presence of a constant current bias and for homogeneous Josephson coupling of all layers, these systems behave exactly as ordinary Josephson junctions, despite their non-canonical current-phase relation. Deviation from this behaviour is found for inhomogeneous Josephson coupling between different layers in the device. Appearance of integer and fractional Shapiro steps are predicted in the presence of r. f. frequency radiation. In particular, the amplitudes of these steps are calculated in the homogeneous case as clear footprints of the non-canonical current-phase relation in these systems.

  1. 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.

  2. 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.

  3. Tunnel junction enhanced nanowire ultraviolet light emitting diodes

    International Nuclear Information System (INIS)

    Polarization engineered interband tunnel junctions (TJs) are integrated in nanowire ultraviolet (UV) light emitting diodes (LEDs). A ∼6 V reduction in turn-on voltage is achieved by the integration of tunnel junction at the base of polarization doped nanowire UV LEDs. Moreover, efficient hole injection into the nanowire LEDs leads to suppressed efficiency droop in TJ integrated nanowire LEDs. The combination of both reduced bias voltage and increased hole injection increases the wall plug efficiency in these devices. More than 100 μW of UV emission at ∼310 nm is measured with external quantum efficiency in the range of 4–6 m%. The realization of tunnel junction within the nanowire LEDs opens a pathway towards the monolithic integration of cascaded multi-junction nanowire LEDs on silicon

  4. 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.

  5. Thoracolumbar junction injuries after rollover crashes: difference between belted and unbelted front seat occupants

    OpenAIRE

    Inamasu, Joji; Guiot, Bernard H.

    2009-01-01

    Motor vehicle collision (MVC) is one of the most common causes of thoracolumbar junction (TLJ) injury. Although it is of no doubt that the use of seatbelt reduces the incidence and severity of MVC-induced TLJ injury, how it is protective for front-seat occupants of an automobile after rollover crashes is unclear. Among 200 consecutive patients with a major TLJ (Th11-L2) injury due to high-energy trauma admitted from 2000 to 2004, 22 patients were identified as front-seat occupants of a four-w...

  6. Neutron Radiation Effect On 2N2222 And NTE 123 NPN Silicon Bipolar Junction Transistors

    Science.gov (United States)

    Oo, Myo Min; Rashid, N. K. A. Md; Karim, J. Abdul; Zin, M. R. Mohamed; Hasbullah, N. F.

    2013-12-01

    This paper examines neutron radiation with PTS (Pneumatic Transfer System) effect on silicon NPN bipolar junction transistors (2N2222 and NTE 123) and analysis of the transistors in terms of electrical characterization such as current gain after neutron radiation. The key parameters are measured with Keithley 4200SCS. Experiment results show that the current gain degradation of the transistors is very sensitive to neutron radiation. The neutron radiation can cause displacement damage in the bulk layer of the transistor structure. The current degradation is believed to be governed by increasing recombination current between the base and emitter depletion region.

  7. Resonance effect in the voltage state of intrinsic Josephson junction stacks with multiple tunneling channels

    Science.gov (United States)

    Koyama, Tomio; Ota, Yukihiro; Machida, Masahiko

    2011-06-01

    We investigate the resonance effect caused by the Josephson-Leggett (JL) mode in intrinsic Josephson junction stacks (IJJs) formed by a stack of multigap superconducting layers. Such an IJJ system is expected to be realized in a single crystal of highly anisotropic iron-based superconductors with thick blocking layers. It is shown that the JL mode is resonantly excited by the Josephson oscillations in the voltage state with inhomogeneous electric-field distribution along the c axis. The resonance creates a steplike structure with a negative resistance region in the I-V characteristics.

  8. S and Te inter-diffusion in CdTe/CdS hetero junction

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, J. Pantoja [Cuerpo Academico-Energia y Sustentabilidad, Universidad Politecnica de Chiapas, Eduardo J. Selvas S/N, Col. Magisterial, Tuxtla Gutierrez 29010, Chiapas (Mexico); Gomez Barojas, E. [CIDS-ICUAP, Apdo. Postal 1651, 72000 Puebla (Mexico); Silva Gonzalez, R.; Pal, U. [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, Puebla (Mexico)

    2007-09-22

    Effects of post formation thermal annealing of the CdTe-CdS device on the inter-diffusion of S and Te at the junction in a substrate configuration device have been studied by Auger electron spectroscopy. While the migration of S and Te atoms increases with annealing temperature, the extent of S diffusion is always higher than the diffusion of Te atoms. Inter-diffusion of S and Te causes the formation of CdTe{sub 1-x}S{sub x} ternary compound at the CdTe-CdS interface. (author)

  9. Neutron Radiation Effect On 2N2222 And NTE 123 NPN Silicon Bipolar Junction Transistors

    International Nuclear Information System (INIS)

    This paper examines neutron radiation with PTS (Pneumatic Transfer System) effect on silicon NPN bipolar junction transistors (2N2222 and NTE 123) and analysis of the transistors in terms of electrical characterization such as current gain after neutron radiation. The key parameters are measured with Keithley 4200SCS. Experiment results show that the current gain degradation of the transistors is very sensitive to neutron radiation. The neutron radiation can cause displacement damage in the bulk layer of the transistor structure. The current degradation is believed to be governed by increasing recombination current between the base and emitter depletion region

  10. Comparison of effective noise temperatures in YBa2BCu3O7-δ junctions

    DEFF Research Database (Denmark)

    Fischer, Gerd Michael; Mygind, Jesper; Pedersen, Niels Falsig

    1997-01-01

    The dc voltage response to 70 GHz radiation was measured for YBCO bicrystal junctions, step edge junctions and ramp edge junctions at temperatures from 4 K to 90 K. Employing the RSJ-model and assuming thermal noise, the Josephson radiation is about equal to the voltage difference of the voltage...... temperature within experimental error. Bicrystal grain boundary junctions with non-zero magnetic field, step edge junctions and ramp edge junctions showed excess noise. The scaling of the noise temperature is compared with the width of the junction in units of the Josephson penetration depth...

  11. 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.

  12. 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.

  13. Parallel Quantum Circuit in a Tunnel Junction.

    Science.gov (United States)

    Faizy Namarvar, Omid; Dridi, Ghassen; Joachim, Christian

    2016-01-01

    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 N(2) power law is preserved for Ωab(N) and for Vab(N). PMID:27453262

  14. Dermal eosinophilic infiltrate in junctional epidermolysis bullosa.

    Science.gov (United States)

    Saraiya, Ami; Yang, Catherine S; Kim, Jinah; Bercovitch, Lionel; Robinson-Bostom, Leslie; Telang, Gladys

    2015-08-01

    Junctional epidermolysis bullosa (JEB) is a rare genodermatosis characterized by a split in the lamina lucida usually because of mutations in LAMA3, LAMB3 and LAMC2 resulting in absence or reduction of laminin-332. Rare subtypes of JEB have mutations in COL17A1, ITGB4, ITGA6 and ITGA3 leading to reduction or dysfunction of collagen XVII, integrin α6β4 and integrin α3. The classic finding under light microscopy is a paucicellular, subepidermal split. We describe the unusual presence of an eosinophilic infiltrate in the bullae and subjacent dermis in a neonate with JEB, generalized intermediate (formerly known as non-Herlitz-type JEB), discuss the histologic differential diagnosis for a subepidermal blister in a neonate, review the literature regarding cases of epidermolysis bullosa (EB) presenting with inflammatory infiltrates, and discuss mechanisms to explain these findings. This case highlights that eosinophils can rarely be seen in EB and should not mislead the dermatopathologist into diagnosing an autoimmune blistering disorder. PMID:25950805

  15. Ferroelectric tunnel junctions with graphene electrodes.

    Science.gov (United States)

    Lu, H; Lipatov, A; Ryu, S; Kim, D J; Lee, H; Zhuravlev, M Y; Eom, C B; Tsymbal, E Y; Sinitskii, A; Gruverman, A

    2014-01-01

    Polarization-driven resistive switching in ferroelectric tunnel junctions (FTJs)--structures composed of two electrodes separated by an ultrathin ferroelectric barrier--offers new physics and materials functionalities, as well as exciting opportunities for the next generation of non-volatile memories and logic devices. Performance of FTJs is highly sensitive to the electrical boundary conditions, which can be controlled by electrode material and/or interface engineering. Here, we demonstrate the use of graphene as electrodes in FTJs that allows control of interface properties for significant enhancement of device performance. Ferroelectric polarization stability and resistive switching are strongly affected by a molecular layer at the graphene/BaTiO3 interface. For the FTJ with the interfacial ammonia layer we find an enhanced tunnelling electroresistance (TER) effect of 6 × 10(5)%. The obtained results demonstrate a new approach based on using graphene electrodes for interface-facilitated polarization stability and enhancement of the TER effect, which can be exploited in the FTJ-based devices. PMID:25417720

  16. 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).

  17. 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).

  18. 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.

  19. Magnetothermopower and magnon-assisted transport in ferromagnetic tunnel junctions

    OpenAIRE

    McCann, Edward; Fal'ko, Vladimir I.

    2002-01-01

    We present a model of the thermopower in a mesoscopic tunnel junction between two ferromagnetic metals based upon magnon-assisted tunneling processes. In our model, the thermopower is generated in the course of thermal equilibration between two baths of magnons, mediated by electrons. We predict a particularly large thermopower effect in the case of a junction between two half-metallic ferromagnets with antiparallel polarizations, $S_{AP} \\sim - (k_B/e)$, in contrast to $S_{P} \\approx 0$ for ...

  20. Phase diffusion and charging effects in Josephson junctions

    OpenAIRE

    Grabert, Hermann; Ingold, Gert-Ludwig; Paul, Benjamin

    1998-01-01

    The supercurrent of a Josephson junction is reduced by phase diffusion. For ultrasmall capacitance junctions the current may be further decreased by Coulomb blockade effects. We calculate the Cooper pair current by means of time-dependent perturbation theory to all orders in the Josephson coupling energy and obtain the current-voltage characteristic in closed form in a range of parameters of experimental interest. The results comprehend phase diffusion of the coherent Josephson current in the...

  1. 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.

  2. 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.

  3. Superpoissonian shot noise in organic magnetic tunnel junctions

    OpenAIRE

    Cascales, Juan Pedro; Hong, Jhen-Yong; Martinez, Isidoro; Lin, Minn-Tsong; Szczepanski, Tomasz; Dugaev, Vitalii K.; Barnas, Jozef; Aliev, Farkad G.

    2015-01-01

    Organic molecules have recently revolutionized ways to create new spintronic devices. Despite intense studies, the statistics of tunneling electrons through organic barriers remains unclear. Here we investigate conductance and shot noise in magnetic tunnel junctions with PTCDA barriers a few nm thick. For junctions in the electron tunneling regime, with magnetoresistance ratios between 10 and 40\\%, we observe superpoissonian shot noise. The Fano factor exceeds in 1.5-2 times the maximum value...

  4. Degeneration of Neuromuscular Junction in Age and Dystrophy

    OpenAIRE

    Rüdiger eRudolf; Muzamil Majid Khan; Siegfried eLabeit; Deschenes, Michael R.

    2014-01-01

    Functional denervation is a hallmark of aging sarcopenia as well as of muscular dystrophy. It is thought to be a major factor reducing skeletal muscle mass, particularly in the case of sarcopenia. Neuromuscular junctions serve as the interface between the nervous and skeletal muscular systems, and thus they may receive pathophysiological input of both pre- and postsynaptic origin. Consequently, neuromuscular junctions are good indicators of motor health on a systemic level. Indeed, upon sarco...

  5. 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.)

  6. 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.

  7. Generation of macroscopic entangled coherent states with large Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Feng-Yang, E-mail: zhangfy1986@gmail.com [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); Yang, Chui-Ping [Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 310036 (China); He, Xiao-Ling [School of Science, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023 (China); Song, He-Shan [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2014-04-01

    We propose a simple and experimental architecture to generate macroscopic entanglement in a solid system which consists of two large Josephson junctions and a flux qubit. Through quantum measuring of flux qubit, entangled coherent states of two large Josephson junctions are obtained. The concurrence of entangled coherent states can be accommodated by adjusted systematic parameters. We also give a brief discussion on the experimental feasibility of this proposal.

  8. Variability study of Si nanowire FETs with different junction gradients

    OpenAIRE

    Jun-Sik Yoon; Kihyun Kim; Taiuk Rim; Chang-Ki Baek

    2016-01-01

    Random dopant fluctuation effects of gate-all-around Si nanowire field-effect transistors (FETs) are investigated in terms of different diameters and junction gradients. The nanowire FETs with smaller diameters or shorter junction gradients increase relative variations of the drain currents and the mismatch of the drain currents between source-drain and drain-source bias change in the saturation regime. Smaller diameters decreased current drivability critically compared to standard deviations...

  9. Topological insulator in junction with ferromagnets: quantum Hall effects

    OpenAIRE

    Chudnovskiy, A. L.; Kagalovsky, V.

    2014-01-01

    The ferromagnet-topological insulator-ferromagnet (FM-TI-FM) junction exhibits thermal and electrical quantum Hall effects. The generated Hall voltage and transverse temperature gradient can be controlled by the directions of magnetizations in the FM leads, which inspires the use of FM-TI-FM junctions as electrical and as heat switches in spintronic devices. Thermal and electrical Hall coefficients are calculated as functions of the magnetization directions in ferromagnets and the spin-relaxa...

  10. Synchronization of intrinsic Josephson junctions to a cavity

    DEFF Research Database (Denmark)

    Filatrella, G.; Pedersen, Niels Falsig

    2004-01-01

    In the utilization of intrinsic Josephson junctions of the highly anisotropic BSCCO type for microwave generation the in-phase motion of fluxons in the different layers is highly desirable but difficult to obtain. We propose to couple each stack junction-which constitutes an underdamped fluxon os...... oscillator-to an external high-Q resonator. We have numerically investigated the possibility for in-phase fluxon synchronization using the external cavity....

  11. Shot noise in magnetic double-barrier tunnel junctions

    OpenAIRE

    Szczepański, T; Dugaev, V. K.; Barnaå, J.; Cascales, J. P.; Aliev, F. G.

    2013-01-01

    We calculate shot noise and the corresponding Fano factors in magnetic double-barrier tunnel junctions. Two situations are analyzed: (i) the central metallic layer is nonmagnetic while the external ones are ferromagnetic, and (ii) all of the metallic layers are ferromagnetic. In the latter case, the number of various magnetic configurations of the junctions is larger, which improves the functionality of such devices. The corresponding shot noise and Fano factor are shown to depend on the magn...

  12. Shot Noise in Magnetic Tunnel Junctions: Evidence for Sequential Tunneling

    OpenAIRE

    Guerrero, R.; Aliev, F. G.; Tserkovnyak, Y.; Santos, T. S.; Moodera, J.S.

    2006-01-01

    We report the experimental observation of sub-Poissonian shot noise in single magnetic tunnel junctions, indicating the importance of tunneling via impurity levels inside the tunnel barrier. For junctions with weak zero-bias anomaly in conductance, the Fano factor (normalized shot noise) depends on the magnetic configuration being enhanced for antiparallel alignment of the ferromagnetic electrodes. We propose a model of sequential tunneling through nonmagnetic and paramagnetic impurity levels...

  13. Prism-coupled light emission from tunnel junctions

    Science.gov (United States)

    Ushioda, S.; Rutledge, J. E.; Pierce, R. M.

    1985-01-01

    Completely p-polarized light emission has been observed from smooth Al-AlO(x)-Au tunnel junctions placed on a prism coupler. The angle and polarization dependence demonstrate unambiguously that the emitted light is radiated by the fast-mode surface plasmon polariton. The emission spectra suggest that the dominant process for the excitation of the fast mode is through conversion of the slow mode to the fast mode mediated by residual roughness on the junction surface.

  14. 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

  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. Observation of negative differential resistance in DNA molecular junctions

    OpenAIRE

    Kang, Ning; Erbe, Artur; Scheer, Elke

    2010-01-01

    The mechanically controllable break junction technique is used to study charge transport through suspended DNA molecules. The current-voltage (I-V) characteristics in an aqueous solution display series of negative differential resistance (NDR) and hysteresis behavior. Under high-vacuum conditions, the peak positions of NDR shift to lower voltage, and the amplitude is reduced dramatically. The observed NDR behavior is consistent with the polarization mechanism in DNA molecular junctions, which...

  17. Charge transport through DNA four-way junctions

    OpenAIRE

    Duncan T Odom; Dill, Erik A.; Barton, Jacqueline K.

    2001-01-01

    Long range oxidative damage as a result of charge transport is shown to occur through single crossover junctions assembled from four semi-complementary strands of DNA. When a rhodium complex is tethered to one of the arms of the four-way junction assembly, thereby restricting its intercalation into the π-stack, photo-induced oxidative damage occurs to varying degrees at all guanine doublets in the assembly, though direct strand scission only occurs at the predicted...

  18. Probing electrical transport in individual carbon nanotubes and junctions

    International Nuclear Information System (INIS)

    The electrical transport properties of individual carbon nanotubes (CNTs) and multi-terminal junctions of CNTs are investigated with a quadraprobe scanning tunneling microscope. The CNTs used in this study are made of stacked herringbone-type conical graphite sheets with a cone angle of ∼20 deg. to the tube axis, and the CNT junctions have no catalytic particles in the junction areas. The CNTs have a significantly higher resistivity than conventional CNTs with concentric walls. The straight CNTs display linear current-voltage (I-V) characteristics, indicating diffusive transport rather than ballistic transport. The structural deformation in CNTs with bends substantially increases the resistivity in comparison with that for the straight segments on the same CNTs, and the I-V curve departs slightly from linearity in curved segments. The junction area of the CNT junctions behaves like an ohmic-type scattering center with linear I-V characteristics. In addition, a gating effect has not been observed, in contrast to the case for conventional multi-walled CNT junctions. These unusual transport properties can be attributed to the enhanced inter-layer interaction in the herringbone-type CNTs.

  19. Heat Transport in Graphene Ferromagnet-Insulator-Superconductor Junctions

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Wei

    2011-01-01

    We study heat transport in a graphene ferromagnet-insulator-superconducting junction. It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor (FIS) junction is an oscillatory function of the barrier strength x in the thin-barrier limit. The gate potential U0 decreases the amplitude of thermal conductance oscillation. Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh. The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.%@@ We study heat transport in a graphene ferromagnet-insulator-superconducting junction.It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor(FIS)junction is an oscillatory function of the barrier strength X in the thin-barrier limit.The gate potential Uo decreases the amplitude of thermal conductance oscillation.Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh.The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.

  20. Electronic Transport in Molecular Junction Based on C20 Cages

    Institute of Scientific and Technical Information of China (English)

    OUYANG Fang-Ping; XU Hui

    2007-01-01

    Choosing closed-ended armchair(5,5)single-wall carbon nanotubes(CCNTs)as electrodes,we investigate the electron transport properties across an all-carbon molecular junction consisting of C20 molecules suspended between two semi-infinite carbon nanotubes.It is shown that the conductances are quite sensitive to the number of C20 molecules between electrodes for both configuration CFl and double-bonded models:the conductances of C20 dimers are markedly smaller than those of monomers.The physics is that incident electrons easily pass the C20 molecules and are predominantly scattered at the C20-C20 junctions.Moreover,we study the doping effect of such molecular junction by doping nitrogen atoms substitutionally.The bonding property of the molecular junction with configuration CFl has been analysed by calculating the Mulliken atomic charges.Our results have revealed that the C atoms in N-doped junctions are more ionic than those in pure-carbon ones,leading to the fact that N-doped junctions have relatively large conductance.

  1. The string-junction picture of multiquark states: an update

    Science.gov (United States)

    Rossi, G. C.; Veneziano, G.

    2016-06-01

    We recall and update, both theoretically and phenomenologically, our (nearly) forty-years-old proposal of a string-junction as a necessary complement to the conventional classification of hadrons based just on their quark-antiquark constituents. In that proposal single (though in general metastable) hadronic states are associated with "irreducible" gauge-invariant operators consisting of Wilson lines (visualized as strings of color flux tubes) that may either end on a quark or an antiquark, or annihilate in triplets at a junction J or an anti-junction overline{J} . For the junction-free sector (ordinary qoverline{q} mesons and glueballs) the picture is supported by large- N (number of colors) considerations as well as by a lattice strong-coupling expansion. Both imply the famous OZI rule suppressing quark-antiquark annihilation diagrams. For hadrons with J and/or overline{J} constituents the same expansions support our proposal, including its generalization of the OZI rule to the suppression of J-overline{J} annihilation diagrams. Such a rule implies that hadrons with junctions are "mesophobic" and thus unusually narrow if they are below threshold for decaying into as many baryons as their total number of junctions (two for a tetraquark, three for a pentaquark). Experimental support for our claim, based on the observation that narrow multiquark states typically lie below (well above) the relevant baryonic (mesonic) thresholds, will be presented.

  2. CANDU bundle junction. Misalignment probability and pressure-drop correlation

    International Nuclear Information System (INIS)

    The pressure drop over the bundle junction is an important component of the pressure drop in a CANDU (Canada Deuterium Uranium) fuel channel. This component can represent from ∼ 15% for aligned bundles to ∼ 26% for rotationally misaligned bundles, and is dependent on the degree of misalignment. The geometry of the junction increases the mixing between subchannels, and hence improves the thermal performance of the bundle immediately downstream. It is therefore important to model the junction's performance adequately. This paper summarizes a study sponsored by COG (CANDU Owners Group) and an NSERC (National Science and Engineering Research Council) Industrial Research Grant, undertaken, at CRL (Chalk River Laboratories) to identify and develop a bundle-junction model for potential implementation in the ASSERT (Advanced Solution of Subchannel Equations in Reactor Thermalhydraulics) subchannel code. The work reported in this paper consists of two components of this project: an examination of the statistics of bundle misalignment, demonstrating that there are no preferred positions for the bundles and therefore all misalignment angles are equally possible; and, an empirical model for the single-phase pressure drop across the junction as a function of the misalignment angle. The second section of this paper includes a brief literature review covering the experimental, analytical and numerical studies concerning the single-phase pressure drop across bundle junctions. 32 refs., 9 figs

  3. Resolving Holliday junctions with Escherichia coli UvrD helicase.

    Science.gov (United States)

    Carter, Annamarie S; Tahmaseb, Kambiz; Compton, Sarah A; Matson, Steven W

    2012-03-01

    The Escherichia coli UvrD helicase is known to function in the mismatch repair and nucleotide excision repair pathways and has also been suggested to have roles in recombination and replication restart. The primary intermediate DNA structure in these two processes is the Holliday junction. UvrD has been shown to unwind a variety of substrates including partial duplex DNA, nicked DNA, forked DNA structures, blunt duplex DNA and RNA-DNA hybrids. Here, we demonstrate that UvrD also catalyzes the robust unwinding of Holliday junction substrates. To characterize this unwinding reaction we have employed steady-state helicase assays, pre-steady-state rapid quench helicase assays, DNaseI footprinting, and electron microscopy. We conclude that UvrD binds initially to the junction compared with binding one of the blunt ends of the four-way junction to initiate unwinding and resolves the synthetic substrate into two double-stranded fork structures. We suggest that UvrD, along with its mismatch repair partners, MutS and MutL, may utilize its ability to unwind Holliday junctions directly in the prevention of homeologous recombination. UvrD may also be involved in the resolution of stalled replication forks by unwinding the Holliday junction intermediate to allow bypass of the blockage. PMID:22267744

  4. Affordance-based individuation of junctions in Open Street Map

    Directory of Open Access Journals (Sweden)

    Simon Scheider

    2012-06-01

    Full Text Available We propose an algorithm that can be used to identify automatically the subset of street segments of a road network map that corresponds to a junction. The main idea is to use turn-compliant locomotion affordances, i.e., restricted patterns of supported movement, in order to specify junctions independently of their data representation, and in order to motivate tractable individuation and classification strategies. We argue that common approaches based solely on geometry or topology of the street segment graph are useful but insufficient proxies. They miss certain turn restrictions essential to junctions. From a computational viewpoint, the main challenge of affordance-based individuation of junctions lies in its complex recursive definition. In this paper, we show how Open Street Map data can be interpreted into locomotion affordances, and how the recursive junction definition can be translated into a deterministic algorithm. We evaluate this algorithm by applying it to small map excerpts in order to delineate the contained junctions.

  5. Characteristics of the Surface-Intrinsic Josephson Junction

    Institute of Scientific and Technical Information of China (English)

    YANG Li; XU Wei-wei; YE Su-li; GUO Da-yuan; YOU Li-xing; WU Pei-heng

    2006-01-01

    During the fabrication of intrinsic Josephson junctions (IJJs) with Bi2Sr2CaCu2O8+δ(BSCCO) single crystals,the superconductivity of the surface Cu-O layer is degraded because of a deposited metal film on top of the stack.Thus,the characteristics of the surface junction consisting of the surface Cu-O double layers remarkably differ from those of the junctions deep in the stack,which will be referred to as ordinary IJJs.The electrical transport characteristics of the surface junction,such as I-V,I'c-T,and R-T,show that the critical temperature T'c of the surface junction is always lower than that of ordinary IJJs,and that the change of its critical current I'c with temperature is different from that of ordinary IIJs.Furthermore,by shunting! the surface junction resistively,we are able to observe the AC Josephson effect at 3-mm waveband.

  6. Renal trauma in occult ureteropelvic junction obstruction: CT findings

    International Nuclear Information System (INIS)

    The aim of this study was to present CT findings of occult ureteropelvic junction obstruction in patients with renal trauma and to describe the clinical signs and singular CT features that are characteristically observed with trauma and are relevant to management of these patients. We retrospectively reviewed 82 helical CT studies in patients with renal trauma referred to our institution. We found 13 cases of occult preexisting renal pathology, six of which were occult ureteropelvic junction obstructions. The clinical presentation, radiologic findings of trauma according to the Federle classification, and CT findings of obstructed ureteropelvic junction are presented. We found three category-I lesions (one in a horseshoe kidney), two of them treated with nephrostomy because of increased ureteropelvic junction obstruction due to pelvic clots; two category-II lesions (parenchymal and renal pelvis lacerations) that had presented only with microhematuria; and one category-IV lesion (pelvic laceration alone). Pelvic extension was demonstrated in all the cases with perirenal collections. The CT studies in all the cases with suspected ureteropelvic junction obstruction showed decreased parenchymal thickness and enhancement, and dilatation of the renal pelvis and calyx, with a normal ureter. Computed tomography can provide information to confidently diagnose underlying ureteropelvic junction obstruction in renal trauma, categorize the traumatic injury (at times clinically silent) and facilitate proper management according to the singularities observed, such us rupture of the renal pelvis alone (Federle category IV) and increasing ureteropelvic obstruction due to clots which can be decompressed by nephrostomy. (orig.)

  7. Synchronisation of Josephson vortices in multi-junction systems

    DEFF Research Database (Denmark)

    Filatrella, G.; Pedersen, Niels Falsig; Wiesenfeld, K.

    2006-01-01

    A largely adopted model for the description of high-temperature superconductors such as BSCCO results in several long Josephson junctions one on the top of the other ("stacked"). The dynamics of the basic nonlinear excitation of the isolated long Josephson junction, the Josephson vortex, is modif......A largely adopted model for the description of high-temperature superconductors such as BSCCO results in several long Josephson junctions one on the top of the other ("stacked"). The dynamics of the basic nonlinear excitation of the isolated long Josephson junction, the Josephson vortex......, is modified by the coupling among the junctions, so the motion of the flux quanta in the various layers is affected by the flux dynamics in all other layers. Two basic states are possible: a synchronous motion, where all junctions are reflected at the edge at the same instant, and an out-of-phase motion......, where vortices in each layer are shifted with respect to neighboring vortices. This is of direct interest for applications since flux quanta emit, upon reflection, radiation at frequencies of great interest (above 100 GHz). Research has been directed towards the optimal conditions to favor such emission...

  8. Engineering design of artificial vascular junctions for 3D printing.

    Science.gov (United States)

    Han, Xiaoxiao; Bibb, Richard; Harris, Russell

    2016-06-01

    Vascular vessels, including arteries, veins and capillaries, are being printed using additive manufacturing technologies, also known as 3D printing. This paper demonstrates that it is important to follow the vascular design by nature as close as possible when 3D printing artificial vascular branches. In previous work, the authors developed an algorithm of computational geometry for constructing smooth junctions for 3D printing. In this work, computational fluid dynamics (CFDs) is used to compare the wall shear stress and blood velocity field for the junctions of different designs. The CFD model can reproduce the expected wall shear stress at locations remote from the junction. For large vessels such as veins, it is shown that ensuring the smoothness of the junction and using smaller joining angles as observed in nature is very important to avoid high wall shear stress and recirculation. The issue is however less significant for capillaries. Large joining angles make no difference to the hemodynamic behavior, which is also consistent with the fact that most capillary junctions have large joining angles. The combination of the CFD analysis and the junction construction method form a complete design method for artificial vascular vessels that can be 3D printed using additive manufacturing technologies. PMID:27321286

  9. Engineering design of artificial vascular junctions for 3D printing.

    Science.gov (United States)

    Han, Xiaoxiao; Bibb, Richard; Harris, Russell

    2016-06-20

    Vascular vessels, including arteries, veins and capillaries, are being printed using additive manufacturing technologies, also known as 3D printing. This paper demonstrates that it is important to follow the vascular design by nature as close as possible when 3D printing artificial vascular branches. In previous work, the authors developed an algorithm of computational geometry for constructing smooth junctions for 3D printing. In this work, computational fluid dynamics (CFDs) is used to compare the wall shear stress and blood velocity field for the junctions of different designs. The CFD model can reproduce the expected wall shear stress at locations remote from the junction. For large vessels such as veins, it is shown that ensuring the smoothness of the junction and using smaller joining angles as observed in nature is very important to avoid high wall shear stress and recirculation. The issue is however less significant for capillaries. Large joining angles make no difference to the hemodynamic behavior, which is also consistent with the fact that most capillary junctions have large joining angles. The combination of the CFD analysis and the junction construction method form a complete design method for artificial vascular vessels that can be 3D printed using additive manufacturing technologies.

  10. Valley detection using a graphene gradual pn junction with spin–orbit coupling: An analytical conductance calculation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Mou, E-mail: yang.mou@hotmail.com [Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Wang, Rui-Qiang [Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Bai, Yan-Kui [College of Physical Science and Information Engineering and Hebei Advance Thin Films Laboratory, Hebei Normal University, Shijiazhuang, Hebei 050024 (China)

    2015-09-04

    Graphene pn junction is the brick to build up variety of graphene nano-structures. The analytical formula of the conductance of graphene gradual pn junctions in the whole bipolar region has been absent up to now. In this paper, we analytically calculated that pn conductance with the spin–orbit coupling and stagger potential taken into account. Our analytical expression indicates that the energy gap causes the conductance to drop a constant value with respect to that without gap in a certain parameter region, and manifests that the curve of the conductance versus the stagger potential consists of two Gaussian peaks – one valley contributes one peak. The latter feature allows one to detect the valley polarization without using double-interface resonant devices. - Highlights: • Analytical conductance formula of the gradual graphene pn junction with spin–orbit coupling in the whole bipolar region. • Exploring the valley-dependent transport of gradual graphene pn junctions analytically. • Conductance peak without resonance.

  11. Photoelectric characteristics of silicon P—N junction with nanopillar texture: Analysis of X-ray photoelectron spectroscopy

    Science.gov (United States)

    Liu, Jing; Wang, Jia-Ou; Yi, Fu-Ting; Wu, Rui; Zhang, Nian; Ibrahim, Kurash

    2014-09-01

    Silicon nanopillars are fabricated by inductively coupled plasma (ICP) dry etching with the cesium chloride (CsCl) islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface are subjected to phosphorus (P) diffusion by liquid dopant source (POCl3) at 870 °C to form P—N junctions with a depth of 300 nm. The X-ray photoelectron spectroscopy (XPS) is used to measure the Si 2p core levels of P—N junction wafer with nanopillar texture and planar surface. With a visible light excitation, the P—N junction produces a new electric potential for photoelectric characteristic, which causes the Si 2p core level to have a energy shift compared with the spectrum without the visible light. The energy shift of the Si 2p core level is -0.27 eV for the planar P—N junction and -0.18 eV for the nanopillar one. The difference in Si 2p energy shift is due to more space lattice defects and chemical bond breaks for nanopillar compared with the planar one.

  12. Maternal uniparental meroisodisomy in the LAMB3 region of chromosome 1 results in lethal junctional epidermolysis bullosa.

    Science.gov (United States)

    Takizawa, Y; Pulkkinen, L; Shimizu, H; Lin, L; Hagiwara, S; Nishikawa, T; Uitto, J

    1998-05-01

    Herlitz junctional epidermolysis bullosa (OMIM#226700) is a lethal, autosomal recessive blistering disorder caused by mutations in one of the three genes LAMA3, LAMB3, or LAMC2, encoding the constitutive polypeptide subunits of laminin 5. In this study, we describe a patient homozygous for a novel nonsense mutation Q936X in exon 19 of LAMB3, which has been mapped to chromosome 1q32. The patient was born with extensive blistering and demonstrated negative immunofluorescence staining for laminin 5, and transmission electron microscopy revealed tissue separation within lamina lucida of the dermal-epidermal junction, diagnostic of Herlitz junctional epidermolysis bullosa. The mother of the proband was found to be a heterozygous carrier for this mutation, whereas the father demonstrated the wild-type LAMB3 allele only. Nonpaternity was excluded by 13 microsatellite markers in six different chromosomes. Genotype analysis using 28 microsatellite markers spanning chromosome 1 revealed that the patient had maternal primary heterodisomy, as well as meroisodisomy within two regions of chromosome 1, one on 1p and the other one on 1q, the latter region containing the maternal LAMB3 mutation. These results suggest that Herlitz junctional epidermolysis bullosa in this patient developed as a result of reduction to homozygosity of the maternal LAMB3 mutation on chromosome 1q32. PMID:9579554

  13. Invasive Bacterial Pathogens Exploit TLR-Mediated Downregulation of Tight Junction Components to Facilitate Translocation across the Epithelium

    OpenAIRE

    Clarke, Thomas B.; Francella, Nicholas; Huegel, Alyssa; Weiser, Jeffrey N.

    2011-01-01

    Streptococcus pneumoniae and Haemophilus influenzae are members of the normal human nasal microbiota with the ability to cause invasive infections. Bacterial invasion requires translocation across the epithelium; however, mechanistic understanding of this process is limited. Examining the epithelial response to murine colonization by S. pneumoniae and H. influenzae, we observed the TLR-dependent downregulation of claudins 7 and 10, tight junction components key to the maintenance of epithelia...

  14. Optimal Normal Tissue Sparing in Craniospinal Axis Irradiation Using IMRT With Daily Intrafractionally Modulated Junction(s)

    Energy Technology Data Exchange (ETDEWEB)

    Kusters, Johannes M.A.M.; Louwe, Rob J.W.; Kollenburg, Peter G.M. van; Kunze-Busch, Martina C. [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Gidding, Corrie E.M. [Department of Pediatric Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Lindert, Erik J. van [Department of Neurosurgery, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Kaanders, Johannes H.A.M. [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands); Janssens, Geert O.R.J., E-mail: g.janssens@rther.umcn.nl [Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen (Netherlands)

    2011-12-01

    Purpose: To develop a treatment technique for craniospinal irradiation using intensity-modulated radiotherapy (IMRT) with improved dose homogeneity at the field junction(s), increased target volume conformity, and minimized dose to the organs at risk (OARs). Methods and Materials: Five patients with high-risk medulloblastoma underwent CT simulation in supine position. For each patient, an IMRT plan with daily intrafractionally modulated junction(s) was generated, as well as a treatment plan based on conventional three-dimensional planning (3DCRT). A dose of 39.6 Gy in 22 daily fractions of 1.8 Gy was prescribed. Dose-volume parameters for target volumes and OARs were compared for the two techniques. Results: The maximum dose with IMRT was <107% in all patients. V{sub <95} and V{sub >107} were <1 cm{sup 3} for IMRT compared with 3-9 cm{sup 3} for the craniospinal and 26-43 cm{sup 3} for the spinal-spinal junction with 3DCRT. These observations corresponded with a lower homogeneity index and a higher conformity index for the spinal planning target volume with IMRT. IMRT provided considerable sparing of acute and late reacting tissues. V{sub 75} for the esophagus, gastroesophageal junction, and intestine was 81%, 81%, and 22% with 3DCRT versus 5%, 0%, and 1% with IMRT, respectively. V{sub 75} for the heart and thyroid was 42% and 32% vs. 0% with IMRT. Conclusion: IMRT with daily intrafractionally modulated junction results in a superior target coverage and junction homogeneity compared with 3DCRT. A significant dose reduction can be obtained for acute as well as late-reacting tissues.

  15. Preparation of a gap junction fraction from uteri of pregnant rats: the 28-kD polypeptides of uterus, liver, and heart gap junctions are homologous

    OpenAIRE

    1985-01-01

    A procedure for the preparation of a gap junction fraction from the uteri of pregnant rats is described. The uterine gap junctions, when examined by electron microscopy of thin sections and in negatively stained preparations, were similar to gap junctions isolated from heart and liver. Major proteins of similar apparent molecular weight (Mr 28,000) were found in gap junction fractions isolated from the uterus, heart, and liver, and were shown to have highly homologous structures by two-dimens...

  16. Reduction of Gap Junctional Conductance by Microinjection of Antibodies against the 27-kDa Liver Gap Junction Polypeptide

    Science.gov (United States)

    Hertzberg, E. L.; Spray, D. C.; Bennett, M. V. L.

    1985-04-01

    Antibody raised against isolated rat liver gap junctions was microinjected into coupled cells in culture to assess its influence on gap junctional conductance. A rapid inhibition of fluorescent dye transfer and electrical coupling was produced in pairs of freshly dissociated adult rat hepatocytes and myocardial cells as well as in pairs of superior cervical ganglion neurons from neonatal rats cultured under conditions in which electrotonic synapses form. The antibodies have been shown by indirect immunofluorescence to bind to punctate regions of the plasma membrane in liver. By immunoreplica analysis of rat liver homogenates, plasma membranes, and isolated gap junctions resolved on NaDodSO4/polyacrylamide gels, binding was shown to be specific for the 27-kDa major polypeptide of gap junctions. This and similar antibodies should provide a tool for further investigation of the role of cell-cell communication mediated by gap junctions and indicate that immunologically similar polypeptides comprise gap junctions in adult mammalian cells derived from all three germ layers.

  17. Vortex dynamics in Josephson junctions arrays

    International Nuclear Information System (INIS)

    In this work we study the dynamics of vortices in two-dimensional overdamped Josephson Junctions Arrays (JJA) driven by dc current in a wide range of conditions varying magnetic field and temperature using experiments, numerical simulations and analytic studies.We develop the Fixed Phase method, a variation of numeric relaxation techniques in which we fix and control the phase of some islands, adjacent to the vortex center, while allowing all other phases in the system to relax.In this way we are able to pull and push the vortex uphill, as we are forcing the center of rotation of the vortex currents to be in a defined location, allowing us to calculate the potential energy of a vortex located in any arbitrary position.We use this method to study the potential energy of a vortex in a variety of situations in homogeneous and non-homogeneous JJA, such as arrays with defects, channel arrays and ratchets.We study the finite size effects in JJA by means of analytic and numerical tools.We implement the rings model, in which we replace the two-dimensional square array by a series of square, concentric, uncoupled rings. This is equivalent to disregarding the radial junctions that couple consecutive rings.In spite of its extreme simplicity, this model holds the main ingredients of the magnetic dependence of the energy.We combine this model with other terms that take into account the dependence in the position of the vortex to obtain a general expression for the potential energy of a vortex in a finite JJA with applied magnetic field.We also present an expression for the first critical field, corresponding to the value of the magnetic field in which the entrance of the first vortex becomes energetically favorable.We build and study JJA modulated to form periodic and asymmetrical potentials for the vortices, named ratchet potentials.The experimental results clearly show the existence of a rectification in the motion of vortices in these potentials.Under certain conditions we

  18. DNA loops and semicatenated DNA junctions

    Directory of Open Access Journals (Sweden)

    Strauss François

    2000-07-01

    Full Text Available Abstract Background Alternative DNA conformations are of particular interest as potential signals to mark important sites on the genome. The structural variability of CA microsatellites is particularly pronounced; these are repetitive poly(CA · poly(TG DNA sequences spread in all eukaryotic genomes as tracts of up to 60 base pairs long. Many in vitro studies have shown that the structure of poly(CA · poly(TG can vary markedly from the classical right handed DNA double helix and adopt diverse alternative conformations. Here we have studied the mechanism of formation and the structure of an alternative DNA structure, named Form X, which was observed previously by polyacrylamide gel electrophoresis of DNA fragments containing a tract of the CA microsatellite poly(CA · poly(TG but had not yet been characterized. Results Formation of Form X was found to occur upon reassociation of the strands of a DNA fragment containing a tract of poly(CA · poly(TG, in a process strongly stimulated by the nuclear proteins HMG1 and HMG2. By inserting Form X into DNA minicircles, we show that the DNA strands do not run fully side by side but instead form a DNA knot. When present in a closed DNA molecule, Form X becomes resistant to heating to 100°C and to alkaline pH. Conclusions Our data strongly support a model of Form X consisting in a DNA loop at the base of which the two DNA duplexes cross, with one of the strands of one duplex passing between the strands of the other duplex, and reciprocally, to form a semicatenated DNA junction also called a DNA hemicatenane.

  19. Preface: Charge transport in nanoscale junctions

    Science.gov (United States)

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-01

    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.

  20. Enamelin Directs Crystallite Organization at the Enamel-Dentine Junction.

    Science.gov (United States)

    Siddiqui, S; Al-Jawad, M

    2016-05-01

    Enamel is an acellular material formed by the intricate process of amelogenesis. Disruption caused at the initial stages of development, by means of mutations in the ENAM gene encoding the enamelin protein, results in enamel hypoplasia. Little is known about the consequence of ENAM mutation on the enamel structure at a crystallographic level. The aim of this study was to characterize the structure of ENAM-mutated enamel to develop a deeper understanding of the role of enamelin protein during formation with regard to crystal organization. Synchrotron X-ray microdiffraction (SXRD) and scanning electron microscopy (SEM) have been used to measure and correlate enamel crystallography and microstructure in hypoplastic and healthy enamel. Rietveld refinement carried out on 2-dimensional diffraction patterns, collected from the Advanced Photon Source, were used to quantify changes in the preferred orientation (crystallographic texture) within the labial regions of each tooth slice and then correlated with the local microstructure. In general, healthy deciduous incisors displayed a higher degree of crystal organization across the labial surface in comparison with the hypoplastic enamel. ENAM plays the greatest functional role at the enamel-dentine junction (EDJ), as it was the region that exhibited lowest texture relative to unaffected controls. Other areas within the tooth, however, such as the cusp tip, displayed greater organization in line with healthy enamel, suggesting its effects are restricted to the early stages of enamel secretion. Observed clinically, the surface of ENAM-mutated hypoplastic enamel can appear to be normal, yet severe sub-nano and microstructural defects appear beneath the subsurface layer. Quantitative characterization of the crystallographic properties from enamel with known genotype expands the understanding of enamel formation processes and can aid better clinical diagnosis and tailor-made treatment.

  1. 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. PMID:25724839

  2. High-field domains in CdS adjacent to a junction of p-type solar cells

    Science.gov (United States)

    Böer, Karl W.

    2016-02-01

    A thin cover layer (150 Å preferred) of copper-doped CdS, when applied on top of any p-type solar cell, can connect this cell directly to an electron-blocking electrode without a pn-junction and increases the open circuit voltage close to its theoretical value; in the example of a CdS/CdTe cell, it increases Voc to its extrapolated value at T = 0 K of the band gap of 1.45 eV. This is caused by a high-field domain that is attached to the junction and limits the field to below tunneling to prevent junction leakage and connects to the CdS that has turned p-type. The large Debye length exceeding the thickness of the CdS forces a direct connection to the electron-blocking cathode with holes tunneling into the metal. The difference of junction-attached high-field domains to the electrode-attached domains, which were described earlier, are given and the consequences are delineated by increasing the conversion efficiency from 8% to 16% in CdTe, while also causing some series resistance limitation. The effect of the added CdS layer is discussed by drawing a to-scale model of the CdS/CdTe solar cell from all experimentally available data and the assumption of the continuity of the hole current. A small jump of the valence band downward is caused by interface recombination. The assistance of high-field domains in CdS is also exemplified by the results of an extremely simple production procedure of the CdS/Cu2S solar cells.

  3. Generators of the auxiliary signals based on the Josephson junctions

    Directory of Open Access Journals (Sweden)

    V. M. Kychak

    2014-06-01

    Full Text Available Introduction and problem statement. Generators based on the Josephson junctions are advisable to use to ensure the generation of signals in the wavelength range from infrared to millimeter. It is necessary to build a dependence of the phase difference of the wave functions superconductor Josephson junctions from the parameters of the equivalent circuit of the resistive shunted tunnel junction. Solution of the problem. An analytical expression for calculating the dependence of the instantaneous voltage values from the parameters of the equivalent circuit resistive shunted Josephson junction is obtained. The dependence of the oscillation period from the parameters of the equivalent circuit elements is researched and a comparison of its values with the period of the output voltage of the generator based on three Josephson junctions is carried out. Conclusions. It is shown that the synchronization leads to decrement in the line width generation and increment the output voltage. Comparison of theoretical calculations and computer modeling shows that the differences do not exceed 25% and therefore they can be used for approximate calculations.

  4. Arrays of Nano Tunnel Junctions as Infrared Image Sensors

    Science.gov (United States)

    Son, Kyung-Ah; Moon, Jeong S.; Prokopuk, Nicholas

    2006-01-01

    Infrared image sensors based on high density rectangular planar arrays of nano tunnel junctions have been proposed. These sensors would differ fundamentally from prior infrared sensors based, variously, on bolometry or conventional semiconductor photodetection. Infrared image sensors based on conventional semiconductor photodetection must typically be cooled to cryogenic temperatures to reduce noise to acceptably low levels. Some bolometer-type infrared sensors can be operated at room temperature, but they exhibit low detectivities and long response times, which limit their utility. The proposed infrared image sensors could be operated at room temperature without incurring excessive noise, and would exhibit high detectivities and short response times. Other advantages would include low power demand, high resolution, and tailorability of spectral response. Neither bolometers nor conventional semiconductor photodetectors, the basic detector units as proposed would partly resemble rectennas. Nanometer-scale tunnel junctions would be created by crossing of nanowires with quantum-mechanical-barrier layers in the form of thin layers of electrically insulating material between them (see figure). A microscopic dipole antenna sized and shaped to respond maximally in the infrared wavelength range that one seeks to detect would be formed integrally with the nanowires at each junction. An incident signal in that wavelength range would become coupled into the antenna and, through the antenna, to the junction. At the junction, the flow of electrons between the crossing wires would be dominated by quantum-mechanical tunneling rather than thermionic emission. Relative to thermionic emission, quantum mechanical tunneling is a fast process.

  5. Measure Guideline: Optimizing the Configuration of Flexible Duct Junction Boxes

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.; Burdick, A.

    2014-03-01

    This measure guideline offers additional recommendations to heating, ventilation, and air conditioning (HVAC) system designers for optimizing flexible duct, constant-volume HVAC systems using junction boxes within Air Conditioning Contractors of America (ACCA) Manual D guidance (Rutkowski, H. Manual D -- Residential Duct Systems, 3rd edition, Version 1.00. Arlington, VA: Air Conditioning Contractors of America, 2009.). IBACOS used computational fluid dynamics software to explore and develop guidance to better control the airflow effects of factors that may impact pressure losses within junction boxes among various design configurations (Beach, R., Prahl, D., and Lange, R. CFD Analysis of Flexible Duct Junction Box Design. Golden, CO: National Renewable Energy Laboratory, submitted for publication 2013). These recommendations can help to ensure that a system aligns more closely with the design and the occupants' comfort expectations. Specifically, the recommendations described herein show how to configure a rectangular box with four outlets, a triangular box with three outlets, metal wyes with two outlets, and multiple configurations for more than four outlets. Designers of HVAC systems, contractors who are fabricating junction boxes on site, and anyone using the ACCA Manual D process for sizing duct runs will find this measure guideline invaluable for more accurately minimizing pressure losses when using junction boxes with flexible ducts.

  6. Thermally assisted vortex motion in intrinsic Josephson junctions

    Science.gov (United States)

    Irie, A.; Oya, G.

    2008-02-01

    The vortex dynamics in intrinsic Josephson junctions (IJJs) at finite temperatures has been investigated numerically by taking into account the thermal fluctuations. Our simulations based on the perturbed, coupled sine-Gordon model successfully reproduce the experimental results associated with the Josephson-vortex flow resistance (JVFR) at low bias currents. Depending on the junction length, bias current, and temperature, the JVFR oscillation is changed from the period of half flux quantum per junction to the period of one flux quantum per junction. It is shown that the oscillation is essentially due to the field dependence of the critical current. At currents slightly exceeding the critical current the stationary vortex lattice structure becomes unstable and an irregular vortex flow can be induced by thermal fluctuations in different junctions. Our simulation results strongly suggest that the triangular lattice of vorticies in the dynamical state is more stable rather than the rectangular one even in a submicrometer IJJ stack when IJJs are biased at a low current.

  7. Controllable 0-π Josephson junctions containing a ferromagnetic spin valve

    Science.gov (United States)

    Gingrich, E. C.; Niedzielski, Bethany M.; Glick, Joseph A.; Wang, Yixing; Miller, D. L.; Loloee, Reza; Pratt, W. P., Jr.; Birge, Norman O.

    2016-06-01

    Superconductivity and ferromagnetism are antagonistic forms of order, and rarely coexist. Many interesting new phenomena occur, however, in hybrid superconducting/ferromagnetic systems. For example, a Josephson junction containing a ferromagnetic material can exhibit an intrinsic phase shift of π in its ground state for certain thicknesses of the material. Such `π-junctions' were first realized experimentally in 2001 (refs ,), and have been proposed as circuit elements for both high-speed classical superconducting computing and for quantum computing. Here we demonstrate experimentally that the phase state of a Josephson junction containing two ferromagnetic layers can be toggled between 0 and π by changing the relative orientation of the two magnetizations. These controllable 0-π junctions have immediate applications in cryogenic memory, where they serve as a necessary component to an ultralow power superconducting computer. Such a fully superconducting computer is estimated to be orders of magnitude more energy-efficient than current semiconductor-based supercomputers. Phase-controllable junctions also open up new possibilities for superconducting circuit elements such as superconducting `programmable logic', where they could function in superconducting analogues to field-programmable gate arrays.

  8. Gap junctions in developing thalamic and neocortical neuronal networks.

    Science.gov (United States)

    Niculescu, Dragos; Lohmann, Christian

    2014-12-01

    The presence of direct, cytoplasmatic, communication between neurons in the brain of vertebrates has been demonstrated a long time ago. These gap junctions have been characterized in many brain areas in terms of subunit composition, biophysical properties, neuronal connectivity patterns, and developmental regulation. Although interesting findings emerged, showing that different subunits are specifically regulated during development, or that excitatory and inhibitory neuronal networks exhibit various electrical connectivity patterns, gap junctions did not receive much further interest. Originally, it was believed that gap junctions represent simple passageways for electrical and biochemical coordination early in development. Today, we know that gap junction connectivity is tightly regulated, following independent developmental patterns for excitatory and inhibitory networks. Electrical connections are important for many specific functions of neurons, and are, for example, required for the development of neuronal stimulus tuning in the visual system. Here, we integrate the available data on neuronal connectivity and gap junction properties, as well as the most recent findings concerning the functional implications of electrical connections in the developing thalamus and neocortex.

  9. The role of the mini-open thoracoscopic-assisted approach in the management of metastatic spine disease at the thoracolumbar junction.

    Science.gov (United States)

    Ravindra, Vijay M; Brock, Andrea; Awad, Al-Wala; Kalra, Ricky; Schmidt, Meic H

    2016-08-01

    OBJECTIVE Treatment advances have resulted in improved survival for many cancer types, and this, in turn, has led to an increased incidence of metastatic disease, specifically to the vertebral column. Surgical decompression and stabilization prior to radiation therapy have been shown to improve functional outcomes, but anterior access to the thoracolumbar junction may involve open thoracotomy, which can cause significant morbidity. The authors describe the treatment of 12 patients in whom a mini-open thoracoscopic-assisted approach (mini-open TAA) to the thoracolumbar junction was used to treat metastatic disease, with an analysis of outcomes. METHODS The authors reviewed a retrospective cohort of patients treated for thoracolumbar junction metastatic disease with mini-open TAA between 2004 and 2016. Data collection included operative time, estimated blood loss, length of stay, follow-up duration, and pre- and postoperative visual analog scale scores and Frankel grades. RESULTS Twelve patients underwent a mini-open TAA procedure for metastatic disease at the thoracolumbar junction. The mean age of patients was 59 years (range 53-77 years), mean estimated blood loss was 613 ml, and the mean duration of the mini-open TAA procedure was 234 minutes (3.8 hours). The median length of stay in the hospital was 7.5 days (range 5-21 days). All 12 patients had significant improvement in their postoperative pain scores in comparison with their preoperative pain scores (p open TAA to the thoracolumbar junction for metastatic disease is a durable procedure that has a reduced morbidity rate compared with traditional open thoracotomy for ventral decompression and fusion. It compares well with traditional and novel posterior approaches to the thoracolumbar junction. The authors found a significant improvement in preoperative pain and neurological symptoms that supports greater use of the mini-open TAA for the treatment of complex metastatic disease at the thoracolumbar junction.

  10. Promoting and avoiding recombination: contrasting activities of the Escherichia coli RuvABC Holliday junction resolvase and RecG DNA translocase.

    Science.gov (United States)

    Zhang, Jing; Mahdi, Akeel A; Briggs, Geoffrey S; Lloyd, Robert G

    2010-05-01

    RuvABC and RecG are thought to provide alternative pathways for the late stages of recombination in Escherichia coli. Inactivation of both blocks the recovery of recombinants in genetic crosses. RuvABC resolves Holliday junctions, with RuvAB driving branch migration and RuvC catalyzing junction cleavage. RecG also drives branch migration, but no nuclease has been identified that might act with RecG to cleave junctions, apart from RusA, which is not normally expressed. We searched for an alternative nuclease using a synthetic lethality assay to screen for mutations causing inviability in the absence of RuvC, on the premise that a strain without any ability to cut junctions might be inviable. All the mutations identified mapped to polA, dam, or uvrD. None of these genes encodes a nuclease that cleaves Holliday junctions. Probing the reason for the inviability using the RusA Holliday junction resolvase provided strong evidence in each case that the RecG pathway is very ineffective at removing junctions and indicated that a nuclease component most probably does not exist. It also revealed new suppressors of recG, which were located to the ssb gene. Taken together with the results from the synthetic lethality assays, the properties of the mutant SSB proteins provide evidence that, rather than promoting recombination, a major function of RecG is to curb potentially pathological replication initiated via PriA protein at sites remote from oriC. PMID:20157002

  11. Cell junction proteins within the cochlea:A review of recent research

    Institute of Scientific and Technical Information of China (English)

    Bo Wang; Bohua Hu; Shiming Yang

    2015-01-01

    Cell—cell junctions in the cochlea are highly complex and well organized. The role of these junctions is to maintain structural and functional integrity of the cochlea. In this review, we describe classification of cell junction-associated proteins identified within the cochlea and provide a brief overview of the function of these proteins in adherent junctions, gap junctions and tight junctions. Copyright © 2016, PLA General Hospital Department of Otolaryngology Head and Neck Surgery. Production and hosting by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

  12. Light Emission Characteristics of Metal/Insulator/Metal and Metal/Insulator/Si Tunnel Junctions Mediated by Surface Plasmon-polaritons

    Institute of Scientific and Technical Information of China (English)

    WANG Mao-xiang; YU Jian-hua; ZHANG You-wen; SUN Cheng-xiu; ZHANG Xu-ping

    2007-01-01

    The Au/Al2O3/Al metal/insulator/metal junction(MIMJ) and Au/SiO2/Si metal/insulator/Si junction(MISJ) have been constructed successfully. The light emission of these junctions was mediated by surface plasmon-polaritons(SPPs) under surface roughness. The light emission from MISJ was more uniform and stable than that from MIMJ. The light power of MISJ was about 2~3 orders higher than that of MIMJ. The light emission spectrum of MISJ was analyzed especially. In the spectrum, there was one main peak located at the wavelength of 610 nm~640 nm, which was mainly due to the couple of SPP with the surface roughness at the Au/air and Au/SiO2 interfaces. A weak peak located at the shorter wavelength region in the spectrum was also found, which was caused by the direct radiation of doped-Si plasma oscillation.

  13. Traumatic Tear of the Latissimus Dorsi Myotendinous Junction

    Science.gov (United States)

    Friedman, Michael V.; Stensby, J. Derek; Hillen, Travis J.; Demertzis, Jennifer L.; Keener, Jay D.

    2015-01-01

    A case of a latissimus dorsi myotendinous junction strain in an avid CrossFit athlete is presented. The patient developed acute onset right axillary burning and swelling and subsequent palpable pop with weakness while performing a “muscle up.” Magnetic resonance imaging examination demonstrated a high-grade tear of the right latissimus dorsi myotendinous junction approximately 9 cm proximal to its intact humeral insertion. There were no other injuries to the adjacent shoulder girdle structures. Isolated strain of the latissimus dorsi myotendinous junction is a very rare injury with a scarcity of information available regarding its imaging appearance and preferred treatment. This patient was treated conservatively and was able to resume active CrossFit training within 3 months. At 6 months postinjury, he had only a mild residual functional deficit compared with his preinjury level. PMID:26502450

  14. Tunnel junctions for InP-on-Si solar cells

    Science.gov (United States)

    Keavney, C.; Vernon, S.; Haven, V.

    1991-01-01

    Growing, by metalorganic chemical vapor deposition, a tunnel junction is described, which makes possible and ohmic back contact in an n-on-p InP solar cell on a silicon substrate. The junction between heavily doped layers of p-type InGaAs and n-type InP shows resistance low enough not to affect the performance of these cells. InP solar cells made on n-type Si substrates with this structure were measured with an efficiency of 9.9 percent. Controls using p-type GaAs substrates showed no significant difference in cell performance, indicating that the resistance associated with the tunnel junction is less than about 0.1 ohm/sq cm.

  15. The distribution of work performed on a NIS junction

    DEFF Research Database (Denmark)

    Santos, Jaime Eduardo Vieira da Silva Moutinho; Ribeiro, Pedro; Kirchner, Stefan

    2016-01-01

    We propose an experimental setup to measure the work performed in a normal-metal/insulator/superconducting (NIS) junction, subjected to a voltage change and in contact with a thermal bath. We compute the performed work and argue that the associated heat release can be measured experimentally. Our...... results are based on an equivalence between the dynamics of the NIS junction and that of an assembly of two-level systems subjected to a circularly polarised field, for which we can determine the work-characteristic function exactly. The average work dissipated by the NIS junction, as well as its...... fluctuations, are determined. From the work characteristic function, we also compute the work probability-distribution and show that it does not have a Gaussian character. Our results allow for a direct experimental test of the Crooks–Tasaki fluctuation relation....

  16. Fabry–Perot filters with tunable Josephson junction defects

    Energy Technology Data Exchange (ETDEWEB)

    Pierro, Vincenzo, E-mail: pierro@unisannio.it [Dept. of Engineering, University of Sannio, Corso Garibaldi, 107, I-82100 Benevento (Italy); Filatrella, Giovanni, E-mail: filatrella@unisannio.it [Dept. of Sciences and Technologies, University of Sannio, Via Port’Arsa, 11, I-82100 Benevento (Italy)

    2015-10-15

    Highlights: • We propose a tunable filter exploiting Josephson junctions nonlinear inductance. • The resonance center frequency is tuned by the external current. • The long Josephson junctions features are within fabrication feasibility. • The full wave analysis of the defect agrees with the linearized approximation. - Abstract: We propose to take advantage of the properties of long Josephson junctions to realize a frequency variable Fabry–Perot filter that operates in the range 100–500 GHz with a bandwidth below 1 GHz. In fact, we show that it is possible to exploit the tunability of the effective impedance of the Josephson component, that is controlled by a dc bias, to tune, up to 10% of the central frequency, the resonance of the system. An analysis of the linearized system indicates the range of operation and the main characteristic parameters. Numerical simulations of the full nonlinear Josephson element confirm the behavior expected from the linear approximation.

  17. Collective Dynamics of Intrinsic Josephson Junctions in HTSC

    Energy Technology Data Exchange (ETDEWEB)

    Shukrinov, Yu M [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow Region, 141980 (Russian Federation); Mahfouzi, F [Institute for Advanced Studies in Basic Sciences, PO Box 45195-1159, Zanjan (Iran, Islamic Republic of)

    2006-06-01

    The dynamics of a stack of intrinsic Josephson junctions (IJJ) in the high-T{sub c} superconductors is theoretically investigated with both the quasineutrality breakdown effect and quasiparticle charge imbalance effect taken into account. The current-voltage characteristics (IVC) of IJJ are numerically calculated in the framework of capacitively coupled Josephson junctions model and charge imbalance model including set of differential equations for phase differences, kinetic equations and generalized Josephson relations. We obtain the branch structure in IVC and investigate it as a function of model parameters such as coupling constant, McCumber parameter and number of junctions in the stack. The dependence of branch slopes and branch endpoints on the coupling and disequilibrium parameters are found. We study the nonequilibrium effects created by current injection and show that the increase in the disequilibrium parameter changes essentially the character of IVC. The new features of the hysteresis behavior of IVC of IJJ are obtained.

  18. Collective Dynamics of Intrinsic Josephson Junctions in HTSC

    Science.gov (United States)

    Shukrinov, Yu M.; Mahfouzi, F.

    2006-06-01

    The dynamics of a stack of intrinsic Josephson junctions (IJJ) in the high-Tc superconductors is theoretically investigated with both the quasineutrality breakdown effect and quasiparticle charge imbalance effect taken into account. The current-voltage characteristics (IVC) of IJJ are numerically calculated in the framework of capacitively coupled Josephson junctions model and charge imbalance model including set of differential equations for phase differences, kinetic equations and generalized Josephson relations. We obtain the branch structure in IVC and investigate it as a function of model parameters such as coupling constant, McCumber parameter and number of junctions in the stack. The dependence of branch slopes and branch endpoints on the coupling and disequilibrium parameters are found. We study the nonequilibrium effects created by current injection and show that the increase in the disequilibrium parameter changes essentially the character of IVC. The new features of the hysteresis behavior of IVC of IJJ are obtained.

  19. Thin film hybrid Josephson junctions with Co doped Ba-122

    International Nuclear Information System (INIS)

    Josephson junctions are a strong tool to investigate fundamental superconducting properties, such as gap behaviour, dependencies from external fields and the order parameter symmetry. Finding secure values enables the possibility of theoretical descriptions to understand the physical processes within the new iron-based superconductors. Based on Co-doped BaFe2As2 (Ba-122) layers produced via pulsed laser deposition (PLD) on (La,Sr)(Al,Ta)O3 substrates, we manufactured superconductor-normal conductor-superconductor (S-N-S) junctions structures by using photolithography, ion beam etching as well as insulating SiO2 layers. We present working Ba-122/Au/PbIn thin film Josephson junctions with different contact areas and barrier thicknesses, their temperature dependence and response to microwave irradiation. The calculated IcRN product is in the range of a couple of microvolts.

  20. Analysis of astronomical data from optical superconducting tunnel junctions

    CERN Document Server

    De Bruijne, J H J; Perryman, M A C; Favata, F; Peacock, A; Bruijne, Jos H.J. de; Reynolds, Alastair P; Perryman, Michael .A.C.; Favata, Fabio; Peacock, Anthony

    2001-01-01

    Currently operating optical superconducting tunnel junction (STJ) detectors, developed in ESA, can simultaneously measure the wavelength (delta lambda = 50 nm at 500 nm) and arrival time (to within ~5 micros) of individual photons in the range 310-720 nm with an efficiency of ~70%, and with count rates of order 5,000 photons per second per junction. A number of STJ junctions placed in an array format generates four-dimensional data: photon arrival time, energy, and array element (X,Y). Such STJ cameras are ideally suited for, e.g., high time- resolution spectrally-resolved monitoring of variable sources or low-resolution spectroscopy of faint extragalactic objects. The reduction of STJ data involves detector efficiency correction, atmo- spheric extinction correction, sky background subtraction, and, unlike that of data from CCD-based systems, a more complex energy calibration, barycentric arrival time correction, energy range selection, and time binning; these steps are, in many respects, analogous to procedu...

  1. Escape Time of Josephson Junctions for Signal Detection

    CERN Document Server

    Addesso, P; Pierro, V

    2014-01-01

    In this Chapter we investigate with the methods of signal detection the response of a Josephson junction to a perturbation to decide if the perturbation contains a coherent oscillation embedded in the background noise. When a Josephson Junction is irradiated by an external noisy source, it eventually leaves the static state and reaches a steady voltage state. The appearance of a voltage step allows to measure the time spent in the metastable state before the transition to the running state, thus defining an escape time. The distribution of the escape times depends upon the characteristics of the noise and the Josephson junction. Moreover, the properties of the distribution depends on the features of the signal (amplitude, frequency and phase), which can be therefore inferred through the appropriate signal processing methods. Signal detection with JJ is interesting for practical purposes, inasmuch as the superconductive elements can be (in principle) cooled to the absolute zero and therefore can add (in practi...

  2. Fluxons in long and annular intrinsic Josephson junction stacks

    Science.gov (United States)

    Clauss, T.; Oehmichen, V.; Mößle, M.; Müller, A.; Weber, A.; Koelle, D.; Kleiner, R.

    2002-12-01

    A promising approach towards a THz oscillator based on intrinsic Josephson junctions in high-temperature superconductors is based on the collective motion of Josephson fluxons, which are predicted to form various configurations ranging from a triangular to a quadratic lattice. Not only for this reason, but certainly also for the sake of basic physics, several experimental and theoretical investigations have been done on the subject of collective fluxon dynamics in stacked intrinsic Josephson junctions. In this paper we will present some experimental results on the fluxon dynamics of long intrinsic Josephson junction stacks made of Bi2Sr2CaCu2O8. The stacks were formed either in an open or in an annular geometry, and clear resonant fluxon modes were observed. Experiments discussed include measurements of current-voltage characteristics in external magnetic fields and in external microwave fields.

  3. Physical understanding of cryogenic implant benefits for electrical junction stability

    Energy Technology Data Exchange (ETDEWEB)

    Adeni Khaja, Fareen; Colombeau, Benjamin; Thanigaivelan, Thirumal; Ramappa, Deepak; Henry, Todd [Applied Materials-Varian Semiconductor Equipment, 35 Dory Road, Gloucester, Massachusetts 01930 (United States)

    2012-03-12

    We investigate the effect of cryogenic temperature implants on electrical junction stability for ultra shallow junction applications for sub-32 nm technology nodes and beyond. A comprehensive study was conducted to gain physical understanding of the impact of cryogenic temperature implants on dopant-defect interactions. Carborane (C{sub 2}B{sub 10}H{sub 12}) molecule, a potential alternative to monomer boron was implanted in carbon preamorphized silicon substrates at cryogenic implant temperatures. Results indicate implants at cryogenic temperatures increase dopant activation with reduced diffusion, resulting in lower sheet resistance for a lower junction depth. Further, this study emphasizes the benefits of co-implants performed at cryogenic temperatures as alternative to traditional preamorphizing implants.

  4. Fabrication of High-Quality Niobium Superconducting Tunnel Junctions

    Institute of Scientific and Technical Information of China (English)

    XU Qin-Yin; CAO Chun-Hai; LI Meng-Yue; JIANG Yi; ZHA Shi-Tong; KANG Lin; XU Wei-Wei; CHEN Jian; WU Pei-Heng

    2011-01-01

    @@ For high-quality superconducting tunnel junctions(STJS), it is necessary to reduce leakage current as much as possible.We describe the fabrication of niobium STJs using the selective niobium(Nb) etching process and various ways to minimize the leakage current.The experiment shows that the leakage current mainly comes from shorts in the tunnel barrier layer rather than those around the junction edges.Through systematic analysis of the thin film stress, surface morphology and modified junction structures, we fabricate high-quality Nb STJs with a gap voltage of 2.8 mV and a leakage current at 1 m V as low as 8.1 % and 0.023% at 4.2K and 0.3 K, respectively.

  5. Superpoissonian shot noise in organic magnetic tunnel junctions

    Science.gov (United States)

    Cascales, Juan Pedro; Hong, Jhen-Yong; Martinez, Isidoro; Lin, Minn-Tsong; Szczepański, Tomasz; Dugaev, Vitalii K.; Barnaś, Józef; Aliev, Farkhad G.

    2014-12-01

    Organic molecules have recently revolutionized ways to create new spintronic devices. Despite intense studies, the statistics of tunneling electrons through organic barriers remains unclear. Here, we investigate conductance and shot noise in magnetic tunnel junctions with 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA) barriers a few nm thick. For junctions in the electron tunneling regime, with magnetoresistance ratios between 10% and 40%, we observe superpoissonian shot noise. The Fano factor exceeds in 1.5-2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. We explain our main findings in terms of a model which includes tunneling through a two level (or multilevel) system, originated from interfacial bonds of the PTCDA molecules. Our results suggest that interfaces play an important role in the control of shot noise when electrons tunnel through organic barriers.

  6. Basilar Artery Aneurysm at a Persistent Trigeminal Artery Junction

    Science.gov (United States)

    Aguiar, G.B.; Conti, M.L.M.; Veiga, J.C.E.; Jory, M.; Souza, R.B.

    2011-01-01

    Summary The trigeminal artery is an anastomosis between the embryonic precursors of the vertebrobasilar and carotid systems, and may persist into adult life. The association of the persistent primitive trigeminal artery (PTA) with cerebral aneurysm is well documented in the literature and, in general, aneurysms are located in the anterior circulation. We describe a patient who presented with a panencephalic Fisher III subarachnoid hemorrhage due to rupture of an intracranial aneurysm. Digital arteriography showed a saccular aneurysm in the middle third of the basilar artery, adjacent to the junction with a persistent trigeminal artery. She was submitted to endovascular treatment with embolization of the basilar artery aneurysm with coils. Aneurysms at the PTA junction with the basilar artery are rare. This paper describes a case of PTA associated with an aneurysm in the basilar artery at PTA junction and briefly reviews the literature. PMID:22005697

  7. Adiabatic quantum pump in a zigzag graphene nanoribbon junction

    Institute of Scientific and Technical Information of China (English)

    张林

    2015-01-01

    The adiabatic electron transport is theoretically studied in a zigzag graphene nanoribbon (ZGNR) junction with two time-dependent pumping electric fields. By modeling a ZGNR p–n junction and applying the Keldysh Green’s function method, we find that a pumped charge current is flowing in the device at a zero external bias, which mainly comes from the photon-assisted tunneling process and the valley selection rule in an even-chain ZGNR junction. The pumped charge current and its ON and OFF states can be efficiently modulated by changing the system parameters such as the pumping frequency, the pumping phase difference, and the Fermi level. A ferromagnetic ZGNR device is also studied to generate a pure spin current and a fully polarized spin current due to the combined spin pump effect and the valley valve effect. Our finding might pave the way to manipulate the degree of freedom of electrons in a graphene-based electronic device.

  8. Claudin heterogeneity and control of lung tight junctions.

    Science.gov (United States)

    Koval, Michael

    2013-01-01

    Lung epithelial cells interconnected by tight junctions provide a barrier to the free diffusion of solutes into airspaces. Transmembrane tight junction proteins known as claudins are essential for epithelial barrier function. Claudins are regulated through interactions with each other that are coordinated with other transmembrane tight junction proteins and cytosolic scaffold proteins. Of the 14 claudins expressed by the alveolar epithelium, claudin-3, claudin-4, and claudin-18 are the most prominent; each confers unique properties to alveolar barrier function. In particular, a protective role for claudin-4 in preventing lung injury has emerged. By contrast, lung diseases that affect claudin expression and impair barrier function, including alcoholic lung syndrome and sepsis, prime the lung for pulmonary edema. Thus, approaches to restore and/or augment lung claudin expression provide potential targets for promoting healthy barrier function. PMID:23072447

  9. Gap junction modulation by extracellular signaling molecules: the thymus model

    Directory of Open Access Journals (Sweden)

    Alves L.A.

    2000-01-01

    Full Text Available Gap junctions are intercellular channels which connect adjacent cells and allow direct exchange of molecules of low molecular weight between them. Such a communication has been described as fundamental in many systems due to its importance in coordination, proliferation and differentiation. Recently, it has been shown that gap junctional intercellular communication (GJIC can be modulated by several extracellular soluble factors such as classical hormones, neurotransmitters, interleukins, growth factors and some paracrine substances. Herein, we discuss some aspects of the general modulation of GJIC by extracellular messenger molecules and more particularly the regulation of such communication in the thymus gland. Additionally, we discuss recent data concerning the study of different neuropeptides and hormones in the modulation of GJIC in thymic epithelial cells. We also suggest that the thymus may be viewed as a model to study the modulation of gap junction communication by different extracellular messengers involved in non-classical circuits, since this organ is under bidirectional neuroimmunoendocrine control.

  10. GaInN-based tunnel junctions with graded layers

    Science.gov (United States)

    Takasuka, Daiki; Akatsuka, Yasuto; Ino, Masataka; Koide, Norikatsu; Takeuchi, Tetsuya; Iwaya, Motoaki; Kamiyama, Satoshi; Akasaki, Isamu

    2016-08-01

    We demonstrated low-resistivity GaInN-based tunnel junctions using graded GaInN layers. A systematic investigation of the samples grown by metalorganic vapor phase epitaxy revealed that a tunnel junction consisting of a 4 nm both-sides graded GaInN layer (Mg: 1 × 1020 cm‑3) and a 2 nm GaN layer (Si: 7 × 1020 cm‑3) showed the lowest specific series resistance of 2.3 × 10‑4 Ω cm2 at 3 kA/cm2 in our experiment. The InN mole fraction in the 4 nm both-sides graded GaInN layer was changed from 0 through 0.4 to 0. The obtained resistance is comparable to those of standard p-contacts with Ni/Au and MBE-grown tunnel junctions.

  11. Single Molecule Junctions: Probing Contact Chemistry and Fundamental Circuit Laws

    Energy Technology Data Exchange (ETDEWEB)

    Hybertsen M. S.

    2013-04-11

    By exploiting selective link chemistry, formation of single molecule junctions with reproducible conductance has become established. Systematic studies reveal the structure-conductance relationships for diverse molecules. I will draw on experiments from my collaborators at Columbia University, atomic-scale calculations and theory to describe progress in two areas. First, I will describe a novel route to form single molecule junctions, based on SnMe3 terminated molecules, in which gold directly bonds to carbon in the molecule backbone resulting in near ideal contact resistance [1]. Second, comparison of the conductance of junctions formed with molecular species containing either one backbone or two backbones in parallel allows demonstration of the role of quantum interference in the conductance superposition law at the molecular scale [2].

  12. Rectifying behaviour of spin coated pn hetero-junction

    Energy Technology Data Exchange (ETDEWEB)

    Yogamalar, N. Rajeswari; Bose, A. Chandra, E-mail: acbose@nitt.edu [Nanomaterials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli – 620 015 (India)

    2015-06-24

    Rectifying pn hetero- junction is fabricated with an acceptor p-type organic semiconductor namely tetra- chloro dihydroxy tetra-iodo fluorescein (Rose Bengal (RB)) followed by an inorganic n-type ZnO semiconductor on indium tin oxide (ITO) substrate. The n-type ZnO films are formed by unintentional doping and doping with aluminium (Al) and yttrium (Y) donors. The surface morphology and the distribution of grains are observed from scanning electron microscopy (SEM) and atomic force microscopy (AFM). The current-voltage (I-V) characteristic of the rectifying diode is measured to characterize the junction properties. The I-V plots obtained from the hetero- junction with electric contact shows a diode characteristic different from that of an ideal behavior. The overall efficiency of the diode exhibits a greater dependency on the film crystallinity, carrier concentration, and reverse saturation current.

  13. Charge Transport across DNA-Based Three-Way Junctions.

    Science.gov (United States)

    Young, Ryan M; Singh, Arunoday P N; Thazhathveetil, Arun K; Cho, Vincent Y; Zhang, Yuqi; Renaud, Nicolas; Grozema, Ferdinand C; Beratan, David N; Ratner, Mark A; Schatz, George C; Berlin, Yuri A; Lewis, Frederick D; Wasielewski, Michael R

    2015-04-22

    DNA-based molecular electronics will require charges to be transported from one site within a 2D or 3D architecture to another. While this has been shown previously in linear, π-stacked DNA sequences, the dynamics and efficiency of charge transport across DNA three-way junction (3WJ) have yet to be determined. Here, we present an investigation of hole transport and trapping across a DNA-based three-way junction systems by a combination of femtosecond transient absorption spectroscopy and molecular dynamics simulations. Hole transport across the junction is proposed to be gated by conformational fluctuations in the ground state which bring the transiently populated hole carrier nucleobases into better aligned geometries on the nanosecond time scale, thus modulating the π-π electronic coupling along the base pair sequence. PMID:25822073

  14. Superpoissonian shot noise in organic magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Cascales, Juan Pedro; Martinez, Isidoro; Aliev, Farkhad G., E-mail: farkhad.aliev@uam.es [Dpto. Fisica Materia Condensada C3, Instituto Nicolas Cabrera (INC), Condensed Matter Physics Institute (IFIMAC), Universidad Autonoma de Madrid, Madrid 28049 (Spain); Hong, Jhen-Yong; Lin, Minn-Tsong, E-mail: mtlin@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 10617, Taiwan and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Szczepański, Tomasz; Dugaev, Vitalii K. [Department of Physics, Rzeszów University of Technology, al. Powstańców Warszawy 6, 35-959 Rzeszów (Poland); Barnaś, Józef [Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland and Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland)

    2014-12-08

    Organic molecules have recently revolutionized ways to create new spintronic devices. Despite intense studies, the statistics of tunneling electrons through organic barriers remains unclear. Here, we investigate conductance and shot noise in magnetic tunnel junctions with 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA) barriers a few nm thick. For junctions in the electron tunneling regime, with magnetoresistance ratios between 10% and 40%, we observe superpoissonian shot noise. The Fano factor exceeds in 1.5–2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. We explain our main findings in terms of a model which includes tunneling through a two level (or multilevel) system, originated from interfacial bonds of the PTCDA molecules. Our results suggest that interfaces play an important role in the control of shot noise when electrons tunnel through organic barriers.

  15. Electric field induced structural modifications in metal/SrTiO{sub 3} junctions and their resistive properties

    Energy Technology Data Exchange (ETDEWEB)

    Stoecker, Hartmut [TU Dresden (Germany). Institut fuer Strukturphysik; TU Bergakademie Freiberg (Germany). Institut fuer Experimentelle Physik; Seibt, Juliane; Hanzig, Florian; Wintz, Susi; Meyer, Dirk C. [TU Bergakademie Freiberg (Germany). Institut fuer Experimentelle Physik; Zschornak, Matthias [TU Dresden (Germany). Institut fuer Strukturphysik

    2010-07-01

    In oxides with perovskite-type of structure, mobile oxygen can cause the formation of non-stoichiometric regions when an electric field of sufficient strength ({proportional_to}1000 V/mm) is applied. Our in-situ investigations of metal/SrTiO{sub 3} junctions revealed reversible structural changes at room temperature caused by a systematic field-induced redistribution of oxygen. The investigations were carried out using wide-angle X-ray scattering, X-ray absorption spectroscopy, photoluminescence, nanoindentation and time-dependent electric I-U measurements. Motivated by the successful use of SrTiO{sub 3} with different doping metals for memory cells on the basis of resistive switching combined with the findings on the major importance of oxygen vacancy redistribution, we show the possibility of realizing a resistance change memory based on vacancy-doped SrTiO{sub 3}. The formation of corresponding metal/SrTiO{sub 3} junctions in an electric field is discussed as well as the switching between ohmic and Schottky-type resistive properties. A notable hysteresis in the I-U characteristics can be used to carry out Write, Read and Erase operations to test the memory cell properties of such junctions.

  16. Elucidation of barrier homogeneity in ZnO/P3HT:PCBM junctions through temperature dependent I-V characteristics

    Science.gov (United States)

    Khare, Neeraj; Zubair Ansari, Mohd; Hoye, Robert L. Z.; Iza, Diana C.; MacManus-Driscoll, Judith L.

    2016-07-01

    The current-voltage (I-V) characteristics of ZnO/P3HT:PCBM junctions using as-deposited ZnO and 300 °C-annealed ZnO (prior to device fabrication) were probed as a function of temperature. The ZnO films were synthesized using two scalable, low temperature methods: Atmospheric pressure spatial atomic layer deposition (AP-SALD) and electrodeposition (ED). In both cases the zero bias Schottky barrier height ({Φ\\text{B}} ) decreases and ideality factor (n) increases with a reduction in the operating temperature of the junctions. This was attributed to the presence of barrier inhomogeneities at the interface from surface states/defects in the ZnO causing a localized variation of work function. For the as-deposited ZnO junctions, two mean barrier heights, arising from a large density of surface states was observed. For the annealed ZnO junction one mean barrier height was observed, indicating reduction in the inhomogeneities of barrier height at the interface for the annealed ZnO. The photoresponce of ZnO/P3HT:PCBM junction was higher for the annealed ZnO which is due to the higher mean barrier height and lower value of ideality factor. This demonstrates that moderate annealing of chemically grown ZnO is crucial for reducing surface defects and barrier inhomogeneities.

  17. Hyperglycaemia and diabetes impair gap junctional communication among astrocytes

    Directory of Open Access Journals (Sweden)

    Gautam K Gandhi

    2010-03-01

    Full Text Available Sensory and cognitive impairments have been documented in diabetic humans and animals, but the pathophysiology of diabetes in the central nervous system is poorly understood. Because a high glucose level disrupts gap junctional communication in various cell types and astrocytes are extensively coupled by gap junctions to form large syncytia, the influence of experimental diabetes on gap junction channel-mediated dye transfer was assessed in astrocytes in tissue culture and in brain slices from diabetic rats. Astrocytes grown in 15–25 mmol/l glucose had a slow-onset, poorly reversible decrement in gap junctional communication compared with those grown in 5.5 mmol/l glucose. Astrocytes in brain slices from adult STZ (streptozotocin-treated rats at 20–24 weeks after the onset of diabetes also exhibited reduced dye transfer. In cultured astrocytes grown in high glucose, increased oxidative stress preceded the decrement in dye transfer by several days, and gap junctional impairment was prevented, but not rescued, after its manifestation by compounds that can block or reduce oxidative stress. In sharp contrast with these findings, chaperone molecules known to facilitate protein folding could prevent and rescue gap junctional impairment, even in the presence of elevated glucose level and oxidative stress. Immunostaining of Cx (connexin 43 and 30, but not Cx26, was altered by growth in high glucose. Disruption of astrocytic trafficking of metabolites and signalling molecules may alter interactions among astrocytes, neurons and endothelial cells and contribute to changes in brain function in diabetes. Involvement of the microvasculature may contribute to diabetic complications in the brain, the cardiovascular system and other organs.

  18. Roles of gap junctions, connexins and pannexins in epilepsy

    Directory of Open Access Journals (Sweden)

    Shanthini eMylvaganam

    2014-05-01

    Full Text Available Enhanced gap junctional communication (GJC between neurons is considered a major factor underlying the neuronal synchrony driving seizure activity. In addition, the hippocampal sharp wave ripple complexes, associated with learning and seizures, are diminished by GJC blocking agents. Although gap junctional blocking drugs inhibit experimental seizures, they all have other nonspecific actions. Besides interneuronal GJC between dendrites, inter-axonal and inter-glial GJC is also considered important for seizure generation. Interestingly, in most studies of cerebral tissue from animal seizure models and from human patients with epilepsy, there is up-regulation of glial, but not neuronal gap junctional mRNA and protein. Significant changes in the expression and post-translational modification of the astrocytic connexin Cx43, and Panx1 were observed in an in vitro Co++ seizure model, further supporting a role for glia in seizure-genesis, although the reasons for this remain unclear. Further suggesting an involvement of astrocytic GJC in epilepsy, is the fact that the expression of astrocytic Cx mRNAs (Cxs 30 and 43 is several fold higher than that of neuronal Cx mRNAs (Cxs 36 and 45, and the number of glial cells outnumber neuronal cells in mammalian hippocampal and cortical tissue. Pannexin expression is also increased in both animal and human epileptic tissues. Specific Cx43 mimetic peptides, Gap 27 and SLS, inhibit the docking of astrocytic connexin Cx43 proteins from forming intercellular gap junctions, diminishing spontaneous seizures. Besides GJs, Cx membrane hemichannels in glia and Panx membrane channels in neurons and glia are also inhibited by gap junctional pharmacological blockers. Although there is no doubt that connexin-based gap junctions and hemichannels, and pannexin-based membrane channels are related to epilepsy, the specific details of how they are involved and how we can modulate their function for therapeutic purposes remain to

  19. Environmental Audit of the Grand Junction Projects Office

    Energy Technology Data Exchange (ETDEWEB)

    1991-08-01

    The Grand Junction Projects Office (GJPO) is located in Mesa County, Colorado, immediately south and west of the Grand Junction city limits. The US Atomic Energy Commission (AEC) established the Colorado Raw Materials Office at the present-day Grand Junction Projects Office in 1947, to aid in the development of a viable domestic uranium industry. Activities at the site included sampling uranium concentrate; pilot-plant milling research, including testing and processing of uranium ores; and operation of a uranium mill pilot plant from 1954 to 1958. The last shipment of uranium concentrate was sent from GJPO in January, 1975. Since that time the site has been utilized to support various DOE programs, such as the former National Uranium Resource Evaluation (NURE) Program, the Uranium Mill Tailings Remedial Action Project (UMTRAP), the Surplus Facilities Management Program (SFMP), and the Technical Measurements Center (TMC). All known contamination at GJPO is believed to be the result of the past uranium milling, analyses, and storage activities. Hazards associated with the wastes impounded at GJPO include surface and ground-water contamination and potential radon and gamma-radiation exposure. This report documents the results of the Baseline Environmental Audit conducted at Grand Junction Projects Office (GJPO) located in Grand Junction, Colorado. The Grand Junction Baseline Environmental Audit was conducted from May 28 to June 12, 1991, by the Office of Environmental Audit (EH-24). This Audit evaluated environmental programs and activities at GJPO, as well as GJPO activities at the State-Owned Temporary Repository. 4 figs., 12 tabs.

  20. Environmental Audit of the Grand Junction Projects Office

    International Nuclear Information System (INIS)

    The Grand Junction Projects Office (GJPO) is located in Mesa County, Colorado, immediately south and west of the Grand Junction city limits. The US Atomic Energy Commission (AEC) established the Colorado Raw Materials Office at the present-day Grand Junction Projects Office in 1947, to aid in the development of a viable domestic uranium industry. Activities at the site included sampling uranium concentrate; pilot-plant milling research, including testing and processing of uranium ores; and operation of a uranium mill pilot plant from 1954 to 1958. The last shipment of uranium concentrate was sent from GJPO in January, 1975. Since that time the site has been utilized to support various DOE programs, such as the former National Uranium Resource Evaluation (NURE) Program, the Uranium Mill Tailings Remedial Action Project (UMTRAP), the Surplus Facilities Management Program (SFMP), and the Technical Measurements Center (TMC). All known contamination at GJPO is believed to be the result of the past uranium milling, analyses, and storage activities. Hazards associated with the wastes impounded at GJPO include surface and ground-water contamination and potential radon and gamma-radiation exposure. This report documents the results of the Baseline Environmental Audit conducted at Grand Junction Projects Office (GJPO) located in Grand Junction, Colorado. The Grand Junction Baseline Environmental Audit was conducted from May 28 to June 12, 1991, by the Office of Environmental Audit (EH-24). This Audit evaluated environmental programs and activities at GJPO, as well as GJPO activities at the State-Owned Temporary Repository. 4 figs., 12 tabs