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1

Formation of Ultra Shallow p+/n Junction in Silicon Using a Combination of Low-Temperature Solid Phase Epitaxy and Non-Melt Double-Pulsed Green Laser Annealing  

NASA Astrophysics Data System (ADS)

MOSFETs scaling-down is an effective way to attain high-performance CMOS operating with lower power and leakage current. However, short channel effects have become a serious problem due to the shortening of channel length. One of the promising methods to suppress this problem is by forming a shallow, highly doped and activated source/drain extension region. Fabricating ultra shallow p+/n junction is difficult due to the channeling of boron ions and anomalous boron diffusion during fabrication processes. A combination of Ge pre-amorphization implantation, low-energy boron implantation and two-step annealing, involving low-temperature solid phase epitaxy preannealing followed by non-melt laser annealing was used for forming ultra shallow p+/n junction in silicon. The physical relationship among the regrowth of implanted layer, boron activation and diffusion, and leakage current is investigated. We have succeeded in forming ultra shallow p+/n junction with junction depth of 8 nm and sheet resistance of 920 ?/\\square.

Aid, Siti Rahmah; Hara, Shuhei; Shigenaga, Yusuke; Fukaya, Takumi; Tanaka, Yuki; Matsumoto, Satoru; Fuse, Genshu; Sakuragi, Susumu

2013-02-01

2

Formation of Ultra Shallow p+/n Junction in Silicon Using a Combination of Low-Temperature Solid Phase Epitaxy and Non-Melt Double-Pulsed Green Laser Annealing  

NASA Astrophysics Data System (ADS)

MOSFETs scaling-down is an effective way to attain high-performance CMOS operating with lower power and leakage current. However, short channel effects have become a serious problem due to the shortening of channel length. One of the promising methods to suppress this problem is by forming a shallow, highly doped and activated source/drain extension region. Fabricating ultra shallow p+/n junction is difficult due to the channeling of boron ions and anomalous boron diffusion during fabrication processes. A combination of Ge pre-amorphization implantation, low-energy boron implantation and two-step annealing, involving low-temperature solid phase epitaxy preannealing followed by non-melt laser annealing was used for forming ultra shallow p+/n junction in silicon. The physical relationship among the regrowth of implanted layer, boron activation and diffusion, and leakage current is investigated. We have succeeded in forming ultra shallow p+/n junction with junction depth of 8 nm and sheet resistance of 920 ?/square.

Rahmah Aid, Siti; Hara, Shuhei; Shigenaga, Yusuke; Fukaya, Takumi; Tanaka, Yuki; Matsumoto, Satoru; Fuse, Genshu; Sakuragi, Susumu

2013-02-01

3

Fabrication of N +\\/P ultra-shallow junctions by plasma doping for 65 nm CMOS technology  

Microsoft Academic Search

As semiconductor devices keep shrinking in size, the fabrication of ultra-shallow junctions (USJ) is becoming a key issue for future CMOS technologies. In this study, we propose for the first time to demonstrate and extensively characterize the capability of plasma doping (PLAD) for fabricating n-type USJ. P-type silicon wafers were used and doped by plasma using AsH3\\/Xe or AsF5 as

F Lallement; A Grouillet; M Juhel; J.-P Reynard; D Lenoble; Z Fang; S Walther; Y Rault; L Godet; J Scheuer

2004-01-01

4

Characterization of Arsenic Ultra-Shallow Junctions in Silicon Using Photocarrier Radiometry and Spectroscopic Ellipsometry  

NASA Astrophysics Data System (ADS)

Photocarrier radiometry (PCR) and spectroscopic ellipsometry (SE) techniques were employed to measure ultra-shallow junction (USJ) wafers. These USJ wafers were prepared by As+ ion implantation at energies of 0.5 keV to 5 keV, at a dose of 1 × 1015 As+/cm2 and spike annealing. The experimental data showed that the PCR signal versus implantation energy exhibits a monotonic behavior. The damaged layer of the as-implanted wafer and the recrystallization and activation of the post-annealed wafer were evaluated by SE in the spectral range from 0.27 ?m to 20 ?m. PCR and SE were shown to provide non-destructive metrology tools for process monitoring in USJ fabrication.

Huang, Qiuping; Li, Bincheng; Gao, Weidong

2012-11-01

5

n-LDD Ultra-Shallow Extension Formation Using Cold and Carbon Ion Implantation  

NASA Astrophysics Data System (ADS)

The sheet resistivity and junction depths of P implants with and without Ge PAI implants and C co-implants were compared. Phosphorus activates well under RTA+LSA annealing conditions, but junction depths did not reach the 15 nm target. Arsenic junctions achieved the junction depth target but with higher sheet resistance. NMOS junction depth was determined to depend heavily on both channeling and transient enhanced diffusion of phosphorus. Combining Ge and C co-implants reduced junction depths to a much larger degree than either species alone. The substitution of the C7H7 molecule for monomer C or the reduction of implant temperature to as low as -40 °C had little effect on the overall sheet resistivity and junction depth. It is possible to eliminate the Ge-PAI for n-LDD if C co-implant energy and dose could be modified. The low implant temperature technique could help the formation of amorphous layer from C co-implant, for which the implant dose and energy need to be tailored in order to reduce junction leakage.

Kuo, P.; Li, C. I.; Lai, H. H.; Liu, R.; Chan, M.; Yang, C. L.; Wu, J. Y.; Ameen, M.; Rubin, L. M.; Tien, E.; Chang, B.

2011-01-01

6

Local Resistance Profiling of Ultra-Shallow Junction with Spike Lamp and Laser Annealing Using Scanning Spreading Resistance Microscopy  

NASA Astrophysics Data System (ADS)

Local resistance profiles of ultra-shallow arsenic implanted into silicon with an energy of 3.5 keV and a dose of 1.2×1015 ions/cm2 activated by conventional spike lamp and laser annealing were measured by SSRM in a nitrogen atmosphere with a depth resolution of less than 10 nm for investigating the combination of the conventional spike lamp and laser annealing. Spike lamp annealing at 1050 °C followed by laser annealing at a power density of 0.42 kW/mm2 was found to give the lowest sheet resistance. The resistance profiles obtained by SSRM also indicated the lowest resistance for the sample after spike lamp annealing at 1050 °C followed by laser annealing with a power density of 0.42 kW/mm2. Laser annealing alone with a power density of 0.42 kW/mm2 resulted in the higher sheet resistance, though the shallower resistance profile could be obtained. Spike lamp annealing followed by laser annealing procedures are effective in activating shallow arsenic profiles.

Abo, Satoshi; Tanaka, Yuji; Nishikawa, Kazuhisa; Wakaya, Fujio; Iwamatsu, Toshiaki; Oda, Hidekazu; Takai, Mikio

2008-11-01

7

Enabling Solutions for 28 nm CMOS Advanced Junction Formation  

NASA Astrophysics Data System (ADS)

Controlling short channel effects for further scaled CMOS is required to take full advantage of the introduction of high K/metal gate or stress induced carrier mobility enhancement. Ultra-Shallow junction formation is necessary to minimize the short channel effects. In this paper, we will discuss the challenges for 28 nm Ultra-Shallow Junction formations in terms of figure of merits of Rs/Xj and junction leakage. We will demonstrate that by adopting and integrating Carborane (CBH, C2B10H12) molecular implant and Phosphorus along with co-implantation and PTC II (VSEA Process Temperature Control) technology, sub-32 nm pLDD and nLDD junction targets can be timely achieved using traditional anneals. Those damage engineering solutions can be readily implemented on state-of-the-art 28 nm device manufacturing.

Li, C. I.; Kuo, P.; Lai, H. H.; Ma, K.; Liu, R.; Wu, H. H.; Chan, M.; Yang, C. L.; Wu, J. Y.; Guo, B. N.; Colombeau, B.; Thirumal, T.; Arevalo, E.; Toh, T.; Shim, K. H.; Sun, H. L.; Wu, T.; Lu, S.

2011-01-01

8

Excimer laser activation of ultra-shallow junctions in doped Si: Modeling, experiments and real time process monitoring  

NASA Astrophysics Data System (ADS)

This work concerns the ALDIP (Laser Activation of Doping agents Implanted by Plasma immersion) project that was a successful collaboration with Ion Beam Services (IBS) corporation, the "Lasers, Plasmas and Photonic Processes" (LP3) laboratory and the GREMI laboratory. The aim of this work is to control the melted thickness (i.e. junction thickness in the range 10-100 nm) by the Real Time Reflectivity (TRR) monitoring during the Laser Thermal Processing (LTP). The LTP is achieved by using a KrF laser beam (248 nm, 27 ns) with a homogeneous 'Top-Hat' space distribution to induce a selective melting and the resolidification of the doped Si:B samples on few nanometers. This recrystallization is conducted here after the pre-amorphisation process resulting from the ionic implantation of Si (PIII IBS implanter). Thus, all the studied samples are partially amorphized and boron doped. TRR method allows the accurate evaluation of the melting threshold, the duration of the melting phase, and the maximum melted thickness. Obtained results versus laser fluence are shown in the new case of under vacuum treatment. In order to calibrate the TRR method (to determine the intensity and the profile of the TRR signal versus the melting depth), we have used the secondary ion mass spectrometry (TOF-SIMS) analysis. This technique gives the doping agents profile versus the depth before and after LTP and confirms also the melting kinetics from TRR results.

Semmar, Nadjib; Darif, Mohamed; Millon, Eric; Petit, Agnès; Etienne, Hasnaa; Delaporte, Philippe

2012-07-01

9

Local Resistance Profiling of Ultra Shallow Junction Annealed with Combination of Spike Lamp and Laser Annealing Processes using Scanning Spreading Resistance Microscope  

NASA Astrophysics Data System (ADS)

Local resistance profiles of ultra shallow boron and arsenic implanted into silicon with energies of 2.0 and 4.0 keV and doses of 2.0×1015 and 1.0×1015 ions/cm2 activated by a combination of conventional spike lamp and laser annealing processes were measured by scanning spreading resistance microscope (SSRM) with a depth resolution of less than 10 nm. The lowest local resistance at the low resistance region in 2.0 keV boron implanted silicon with 1050 °C spike lamp annealing followed by 0.35 kW/mm2 laser annealing was half of that without laser annealing. The lowest local resistance at the low resistance region in the arsenic implanted silicon activated by 1050 °C spike lamp annealing followed by 0.39 kW/mm2 laser annealing was 74% lower than that followed by 0.36 kW/mm2 laser annealing. The lowest local resistances at the low resistance regions in the arsenic implanted silicon with 0.36 and 0.39 kW/mm2 laser annealing followed by 1050 °C spike lamp annealing were 41 and 33% lower than those with spike lamp annealing followed by laser annealing. Laser annealing followed by spike lamp annealing could suppress the diffusion of the impurities and was suitable for making the ultra shallow and low resistance regions.

Abo, Satoshi; Nishikawa, Kazuhisa; Ushigome, Naoya; Wakaya, Fujio; Iwamatsu, Toshiaki; Oda, Hidekazu; Takai, Mikio

2011-01-01

10

Active dopant profiling of ultra shallow junction annealed with combination of spike lamp and laser annealing processes using scanning spreading resistance microscopy  

NASA Astrophysics Data System (ADS)

Depth profiles of a spreading resistance of ultra-shallow arsenic implanted into silicon with an energy of 3.0 keV and a dose of 1.0 × 1015ions/cm2 activated by a combination of conventional spike lamp and laser annealing processes were measured by scanning spreading resistance microscopy (SSRM) with a depth resolution of less than 5 nm. The lowest resistances at the arsenic activated region annealed by laser followed by spike lamp annealing (a laser first process) were lower than those by spike lamp annealing followed by laser annealing (a spike first process) with the same laser power densities. The lowest resistances at the arsenic activated region annealed by the laser and spike first processes with a laser power density of 0.39 kW/mm2 were lower than those with a laser power density of 0.36kW/mm2. The laser first process was suitable for the lower resistance regions than the spike first process.

Abo, Satoshi; Ushigome, Naoya; Osae, Hidenori; Wakaya, Fujio; Iwamatsu, Toshiaki; Oda, Hidekazu; Takai, Mikio

2012-11-01

11

Beyond TED: Understanding Boron Shallow Junction Formation Scott T. Dunham,y  

E-print Network

-low energy implants and short, high temper- ature RTP annealing has greatly diminished the impor- tance 02215 z Dept. of Manufacturing Engineering, Boston University, Boston, MA 02215 Abstract As implant of TED in ultra-shallow boron junctions. Reducing the implant energy is particularly eective as it puts

Dunham, Scott

12

Activation and thermal stability of ultra-shallow B{sup +}-implants in Ge  

SciTech Connect

The activation and thermal stability of ultra-shallow B{sup +} implants in crystalline (c-Ge) and preamorphized Ge (PA-Ge) following rapid thermal annealing was investigated using micro Hall effect and ion beam analysis techniques. The residual implanted dose of ultra-shallow B{sup +} implants in Ge was characterized using elastic recoil detection and was determined to correlate well with simulations with a dose loss of 23.2%, 21.4%, and 17.6% due to ion backscattering for 2, 4, and 6 keV implants in Ge, respectively. The electrical activation of ultra-shallow B{sup +} implants at 2, 4, and 6 keV to fluences ranging from 5.0 Multiplication-Sign 10{sup 13} to 5.0 Multiplication-Sign 10{sup 15} cm{sup -2} was studied using micro Hall effect measurements after annealing at 400-600 Degree-Sign C for 60 s. For both c-Ge and PA-Ge, a large fraction of the implanted dose is rendered inactive due to the formation of a presumable B-Ge cluster. The B lattice location in samples annealed at 400 Degree-Sign C for 60 s was characterized by channeling analysis with a 650 keV H{sup +} beam by utilizing the {sup 11}B(p, {alpha})2{alpha} nuclear reaction and confirmed the large fraction of off-lattice B for both c-Ge and PA-Ge. Within the investigated annealing range, no significant change in activation was observed. An increase in the fraction of activated dopant was observed with increasing energy which suggests that the surface proximity and the local point defect environment has a strong impact on B activation in Ge. The results suggest the presence of an inactive B-Ge cluster for ultra-shallow implants in both c-Ge and PA-Ge that remains stable upon annealing for temperatures up to 600 Degree-Sign C.

Yates, B. R.; Darby, B. L.; Jones, K. S. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Petersen, D. H. [DTU Nanotech, Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Hansen, O. [DTU Nanotech, Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); CINF, Center for Individual Nanoparticle Functionality, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Lin, R.; Nielsen, P. F. [CAPRES A/S, Scion-DTU, DK-2800 Kgs. Lyngby (Denmark); Romano, L. [IMM-CNR MATIS and Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Doyle, B. L. [Sandia National Laboratories, MS-1056, Albuquerque, New Mexico 87185 (United States); Kontos, A. [Applied Materials, Gloucester, Massachusetts 01930 (United States)

2012-12-15

13

Analysis of Tight Junction Formation and Integrity  

SciTech Connect

In this paper, we study segmentation of tight junctions and analyze the formation and integrity of tight junctions in large-scale confocal image stacks, a challenging biological problem because of the low spatial resolution images and the presence of breaks in tight junction structure. We present an automated, three-step processing approach for tight junction analysis. In our approach, we first localize each individual nucleus in the image by using thresholding, morphological filters and active contours. By using each nucleus position as a seed point, we automatically segment the cell body based on the active contour. We then use an intensity-based skeletonization algorithm to generate the boundary regions for each cell, and features are extracted from tight junctions associated with each cell to assess tight junction continuity. Based on qualitative results and quantitative comparisons, we show that we are able to automatically segment tight junctions and compute relevant features that provide a quantitative measure of tight junction formation to which the permeability of the cell monolayer can ultimately be correlated.

Karakaya, Mahmut [ORNL; Kerekes, Ryan A [ORNL; Morrell-Falvey, Jennifer L [ORNL; Foster, Carmen M [ORNL; Retterer, Scott T [ORNL

2012-01-01

14

Loss of implanted heavy elements during annealing of ultra-shallow ion-implanted silicon: The complete picture  

NASA Astrophysics Data System (ADS)

From the observations of the annealing process of ultra-shallow Sn and Pb implanted Si, we propose the mechanism and the triggering conditions for the dopant dose loss effect commonly observed in heavy ion-implanted silicon. The results of high-resolution Rutherford backscattering spectrometry, high-resolution cross-sectional transmission electron microscopy and Monte Carlo simulations are presented. With these results, we construct a complete chain of events that leads to the loss of most of the implanted ions. First, the implanted atoms agglomerate into liquid melts during high temperature electron beam annealing, causing polycrystalline phase formation. Next, liquid phase movement takes place along grain boundaries, and the implanted atoms are forced out of the surface layer as the grain boundaries disappear during grain growth, leaving behind low concentrations of residual atoms. The specific conditions that trigger such a sequence of processes are identified.

Chan, T. K.; Koh, S. Y.; Fang, V.; Markwitz, A.; Osipowicz, T.

2014-09-01

15

Nitric oxide enhances de novo formation of endothelial gap junctions  

Microsoft Academic Search

Objective: Gap junctions (formed by connexins, Cx) are important for functional coordination of cells in the vascular wall. However, little is known about their physiological regulation in this tissue. We examined the effects of nitric oxide (NO), an important mediator of vasomotion, wound healing and angiogenesis, on the formation of gap junctions in endothelial cells (human umbilical vein endothelial cells,

Anke Hoffmann; Torsten Gloe; Ulrich Pohl; Stefan Zahler

2003-01-01

16

Semiconductor junction formation by directed heat  

DOEpatents

The process of the invention includes applying precursors 6 with N- and P-type dopants therein to a silicon web 2, with the web 2 then being baked in an oven 10 to drive off excessive solvents, and the web 2 is then heated using a pulsed high intensity light in a mechanism 12 at 1100.degree.-1150.degree. C. for about 10 seconds to simultaneously form semiconductor junctions in both faces of the web.

Campbell, Robert B. (Pittsburgh, PA)

1988-03-24

17

Photocarrier Radiometry Characterization of Ultra-shallow Junctions (USJ) in Silicon with Excimer Laser Irradiation  

NASA Astrophysics Data System (ADS)

The activation and recrystallization in arsenic ion-implanted silicon under excimer laser (193 nm) irradiation is investigated using photocarrier radiometry (PCR). Arsenic ion-implanted silicon wafers with a dose of 1 × 10^{15} cm^{-2} and an energy of 1 keV were irradiated at different laser parameters, such as the laser fluence, shot number, and repetition rate. The excimer laser irradiation-induced enhancement of PCR signals of implanted silicon samples showed that the implantation-induced crystalline structural damage was reduced and the implanted ions were effectively activated.

Wang, Qian; Li, Bincheng; Ren, Shengdong; Wang, Qiang

2014-04-01

18

Get Ready to Wnt: Prepatterning in Neuromuscular Junction Formation  

PubMed Central

Clustering of acetylcholine receptors (AChR) in muscle fibers prior to innervation by motor neurons is thought to be involved in neuromuscular junction formation. Jing et al. now report in Neuron that this prepatterning of AChRs, via a novel MuSK-dependent Wnt pathway, may guide motor axons to the central region of muscle fibers for synapse formation in zebrafish. PMID:19289078

Zhang, Bin; Xiong, Wen C.; Mei, Lin

2014-01-01

19

Fabrication of sub-40-nm p-n junctions for 0.18 {mu}m MOS device applications using a cluster-tool-compatible, nanosecond thermal doping technique  

SciTech Connect

In this paper, we introduced an alternative deep-submicrometer doping technology, Projection Gas Immersion Laser Doping (P-GILD). Representing the marriage of lithography and diffusion, P-GILD is a resistless, step-and-repeat doping process that utilizes excimer laser light patterned by a dielectric reticle to selectively heat and, thereby, dope regions of an integrated circuit. Results of physical and electrical characterization are presented for ultra-shallow p{sup +} {minus}n and n{sup +} {minus}p junctions produced by gas immersion laser doping (GILD), a phenomenologically identical technique that utilizes an aluminum contact mask rather than a dielectric reticle to pattern the beam. Junctions produced using GILD exhibit uniformly-doped, abrupt impurity profiles with no apparent defect formation in the silicon. Electrically, sheet and contact resistivities of the ultra-shallow junctions are less than 100{Omega}/sheet and 1 {times} 10{sup {minus}6} {Omega}{sm_bullet}cm{sup 2}, respectively, while n{sup +} {minus}p and p{sup +} {minus}n diodes exhibit nearly ideal forward bias behavior and reverse leakage current densities less than 5 nA/cm{sup 2} at {minus}5V. Uniformity of both diode characteristics and sheet resistance for junctions produced by the step-and-repeat process is also shown to be better than {plus_minus}5% across a 4-inch wafer.

Weiner, K.H.; McCarthy, A.M.

1993-09-20

20

An ultra-shallow water storm surge model with quadratically depth-varying eddy viscosity and its application to the numerical modelling of the Bohai Sea storm surges  

Microsoft Academic Search

Based on the ultra-shallow water storm surge theory proposed by Qin and Feng[1] (1975), an ultra-shallow water storm surge model, taking into consideration the effect of the earth's rotation and the quadratically\\u000a depth-varying eddy viscosity, is developed. Using the model wind stress fields as a guide for representing the effect of wind\\u000a stress forcing in our model, a numerical investigation

Dexing Wu; Zenghao Qin

1985-01-01

21

?-Catenin gain of function in muscles impairs neuromuscular junction formation  

PubMed Central

Neuromuscular junction (NMJ) formation requires proper interaction between motoneurons and muscle cells. ?-Catenin is required in muscle cells for NMJ formation. To understand underlying mechanisms, we investigated the effect of ?-catenin gain of function (GOF) on NMJ development. In HSA-?-catflox(ex3)/+ mice, which express stable ?-catenin specifically in muscles, motor nerve terminals became extensively defasciculated and arborized. Ectopic muscles were observed in the diaphragm and were innervated by ectopic phrenic nerve branches. Moreover, extensive outgrowth and branching of spinal axons were evident in the GOF mice. These results indicate that increased ?-catenin in muscles alters presynaptic differentiation. Postsynaptically, AChR clusters in HSA-?-catflox(ex3)/+ diaphragms were distributed in a wider region, suggesting that muscle ?-catenin GOF disrupted the signal that restricts AChR clustering to the middle region of muscle fibers. Expression of stable ?-catenin in motoneurons, however, had no effect on NMJ formation. These observations provide additional genetic evidence that pre- and postsynaptic development of the NMJ requires an intricate balance of ?-catenin activity in muscles. PMID:22627288

Wu, Haitao; Lu, Yisheng; Barik, Arnab; Joseph, Anish; Taketo, Makoto Mark; Xiong, Wen-Cheng; Mei, Lin

2012-01-01

22

Ion oxidation mechanisms controlling the formation of barriers in magnetic tunnel junctions  

E-print Network

Ion oxidation mechanisms controlling the formation of barriers in magnetic tunnel junctions B. F. P, United Kingdom The oxidation mechanisms of the formation of thin insulating barriers in magnetic tunnel junctions are studied. The barriers are prepared by means of an oxidation technique using a highly

Demokritov, S.O.

23

Adherens Junction Formation Inhibits Lentivirus Entry and Gene Transfer  

PubMed Central

Although cellular signaling pathways that affect lentivirus infection have been investigated, the role of cell-cell interactions in lentiviral gene delivery remains elusive. In the course of our studies we observed that lentiviral gene transfer was a strong function of the position of epithelial cells within colonies. While peripheral cells were transduced efficiently, cells in the center of colonies were resistant to gene transfer. In addition, gene delivery was enhanced significantly under culture conditions that disrupted adherens junctions (AJ) but decreased upon AJ formation. In agreement, gene knockdown and gain-of-function approaches showed that ?-catenin, a key component of the AJ complex prevented lentivirus gene transfer. Using a doxycycline regulatable system we showed that expression of dominant negative E-cadherin enhanced gene transfer in a dose-dependent manner. In addition, dissolution of AJ by doxycycline increased entry of lentiviral particles into the cell cytoplasm in a dose-dependent manner. Taken together our results demonstrate that AJ formation renders cells non-permissive to lentiviral gene transfer and may facilitate development of simple means to enhance gene delivery or combat virus infection. PMID:24236116

Padmashali, Roshan; You, Hui; Karnik, Nikhila; Lei, Pedro; Andreadis, Stelios T.

2013-01-01

24

Characterization of dopant profiles produced by ultra-shallow As implantation and spike annealing using medium energy ion scattering  

NASA Astrophysics Data System (ADS)

Medium energy ion scattering (MEIS) combining a toroidal electrostatic analyzer with an energy resolution (d E/ E) of 4 × 10 -3 has been used for ultra-shallow depth profiling of As implanted into Si at 1, 2 and 5 keV to a dose of 1.2 × 10 15 ions/cm 2 before and after spike annealing at 1075 °C. Depth profiling results extracted from MEIS spectra were compared with those of simulation and SIMS measurement. The arsenic re-distribution close to the surface after spike annealing was found by MEIS and SIMS measurements.

Ichihara, S.; Nakagawa, T.; Nitta, M.; Abo, S.; Lohner, T.; Angelov, C.; Ohta, K.; Takai, M.

2004-06-01

25

Numerical Simulation on the Horseshoe Vortex Formation Around the Hull-Sail Junction of Submarine  

Microsoft Academic Search

The horseshoe vortex is typical flow characteristic around the appendage-body junction. The horseshoe vortex formation around the hull-said junction has important influence on the submarine hydrodynamics performance. The origination process of the submarine horseshoe vertex and its influence on submarine flow is analyzed. The numerical simulation on the horseshoe vortex is carried out using DES method (Detached Eddies Simulation); the

Liu Zhihua; Xiong Ying

2010-01-01

26

Dopant profiling of ultra shallow As implanted in Si with and without spike annealing using medium energy ion scattering  

NASA Astrophysics Data System (ADS)

Ultra shallow dopant profiles of arsenic implanted into Si with an energy range from 0.5 to 3 keV to a dose of 8 × 10 14 ions/cm 2 with and without spike annealing were measured by medium energy ion scattering (MEIS) with a toroidal electrostatic analyzer (TEA). A shift of the peak of arsenic profile to the surface after spike annealing was observed by MEIS measurement. Most of the implanted arsenic atoms were trapped in the native oxide layer after spike annealing. A recovery of silicon crystal defects induced by arsenic implantation was observed after spike annealing by glancing angle Rutherford back scattering (RBS) measurement with a solid-state detector. The thickness of disordered Si layers down to 1.5 nm was evaluated from glancing angle RBS measurements for implanted sample before and after spike annealing.

Abo, S.; Ichihara, S.; Lohner, T.; Wakaya, F.; Eimori, T.; Inoue, Y.; Takai, M.

2005-08-01

27

V(D)J recombination coding junction formation without DNA homology: processing of coding termini.  

PubMed Central

Coding junction formation in V(D)J recombination generates diversity in the antigen recognition structures of immunoglobulin and T-cell receptor molecules by combining processes of deletion of terminal coding sequences and addition of nucleotides prior to joining. We have examined the role of coding end DNA composition in junction formation with plasmid substrates containing defined homopolymers flanking the recombination signal sequence elements. We found that coding junctions formed efficiently with or without terminal DNA homology. The extent of junctional deletion was conserved independent of coding ends with increased, partial, or no DNA homology. Interestingly, G/C homopolymer coding ends showed reduced deletion regardless of DNA homology. Therefore, DNA homology cannot be the primary determinant that stabilizes coding end structures for processing and joining. PMID:8413286

Boubnov, N V; Wills, Z P; Weaver, D T

1993-01-01

28

Droplet formation in microfluidic T-junction generators operating in the transitional regime. I. Experimental observations.  

PubMed

This is the first part of a two-part study on the generation of droplets at a microfluidic T-junction operating in the transition regime where confinement of the droplet creates a large squeezing pressure that influences droplet formation. In this regime, the operation of the T-junction depends on the geometry of the intersection (height-to-width ratio, inlet width ratio), capillary number, flow ratio, and viscosity ratio of the two phases. Here in paper I we presented our experimental observations through the analysis of high-speed videos of the droplet formation process. Various parameters are tracked during the formation cycle such as the shape of the droplet (penetration depth and neck), interdroplet spacing, production rate, and flow of both phases across several T-junction designs and flow conditions. Generally, the formation process is defined by a two-stage model consisting of an initial filling stage followed by a necking stage. However, video evidence suggests the inclusion of a third stage, which we term the lag stage, at the beginning of the formation process that accounts for the retraction of the interface back into the injection channel after detachment. Based on the observations made in this paper, a model is developed to describe the formation process in paper II, which can be used to understand the design and operation of T-junction generators in the transition regime. PMID:22400672

Glawdel, Tomasz; Elbuken, Caglar; Ren, Carolyn L

2012-01-01

29

Application of laser annealing to solar cell junction formation  

NASA Technical Reports Server (NTRS)

The possibility of using high-energy Q-switched Nd:glass lasers to form pn junctions in solar cells by annealing ion-implanted substrates is investigated. The properties of laser annealed cells are analyzed by electrical, transmission electron microscopy, Rutherford backscattering and secondary ion mass spectrometry techniques. Tests indicate the laser annealed substrates to be damage-free and electrically active. Similar reference analysis of ion-implanted furnace-annealed substrates reveals the presence of residual defects in the form of dislocation lines and loops with substantial impurity redistribution evident for some anneal temperature/time regimes. Fabricated laser annealed cells exhibit excellent conversion efficiency. It is noted that additional improvements are anticipated once the anneal parameters for a back surface field are optimized.

Katzeff, J. S.; Lopez, M.; Josephs, R. H.

1981-01-01

30

Basic Aspects of the Formation and Activation of Boron Junctions Using Plasma Immersion Ion Implantation  

SciTech Connect

This study investigates the basic aspects of junction formation using Plasma Immersion Ion Implantation using BF{sub 3} and addresses the role of (pre)amorphization, C(F)-co-implantation, plasma parameters (bias, dose) and the thermal anneal cycle (spike versus msec laser anneal). The basic physics are studied using Secondary Ion Mass Spectrometry, sheet resistance and using four point probe and RsL. Profiles with junction depths ranging from 10-12 nm and sheet resistance values below 800 Ohm/sq are readily achievable.

Zschaetzsch, G. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Instituut for Kern-en Stralingsfysica, K.U. Leuven, B-3001 Leuven (Belgium); Vandervorst, W. [Instituut for Kern-en Stralingsfysica, K.U. Leuven, B-3001 Leuven (Belgium); Hoffmann, T.; Goossens, J.; Everaert, J.-L. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Agua Borniquel, J. I. del; Poon, T. [Applied Materials, 974 E. Arques Avenue-Sunnyvale-CA 94087 (United States)

2008-11-03

31

Void formation of nanocrystalline materials at the triple junction of grain boundaries  

NASA Astrophysics Data System (ADS)

A theoretical model of void formation at the triple junction of grain boundaries is described. Based on the combined effects of grain boundary diffusional creep and triple junction diffusional creep as well as dislocation climb, void formation time and void growth rate are derived. The results indicate that vacancy concentration increases with increasing creep strain rate and the angle of the Burgers vector to its dislocation line, and with decreasing grain size. It sharply declines at low creep strain rates, then the asymptotic behavior approaches a constant at high rates. It is also found that the dislocation density is noticeable for small grain sizes in nanocrystalline Cu, and the void growth rate decreases with creep strain rate and time, which are qualitatively consistent with the conclusions in previous work (Dongare et al 2010 J. Appl. Phys. 108 113518; Du et al 2010 Mater. Sci. Eng. A 527 4837).

Li, Jia; Fang, Qihong; Liu, Youwen

2014-03-01

32

Effect of geometry on droplet formation in the squeezing regime in a microfluidic T-junction  

Microsoft Academic Search

In the surface tension-dominated microchannel T-junction, droplets can be formed as a result of the mixing of two dissimilar,\\u000a immiscible fluids. This article presents results for very low Capillary numbers and different flow rates of the continuous\\u000a and dispersed phases. Through three-dimensional lattice Boltzmann-based simulations, the mechanism of the formation of “plugs”\\u000a in the squeezing regime has been examined and

Amit Gupta; Ranganathan Kumar

2010-01-01

33

Experimental validation of plugging during drop formation in a T-junction.  

PubMed

At low capillary number, drop formation in a T-junction is dominated by interfacial effects: as the dispersed fluid flows into the drop maker nozzle, it blocks the path of the continuous fluid; this leads to a pressure rise in the continuous fluid that, in turn, squeezes on the dispersed fluid, inducing pinch-off of a drop. While the resulting drop volume predicted by this "squeezing" mechanism has been validated for a range of systems, as of yet, the pressure rise responsible for the actual pinch-off has not been observed experimentally. This is due to the challenge of measuring the pressures in a T-junction with the requisite speed, accuracy, and localization. Here, we present an empirical study of the pressures in a T-junction during drop formation. Using Laplace sensors, pressure probes we have developed, we confirm the central ideas of the squeezing mechanism; however, we also uncover other findings, including that the pressure of the dispersed fluid is not constant but rather oscillates in anti-phase with that of the continuous fluid. In addition, even at the highest capillary number for which monodisperse drops can be formed, pressure oscillations persist, indicating that drop formation in confined geometries does not transition to an entirely shear-driven mechanism, but to a mechanism combining squeezing and shearing. PMID:22402628

Abate, Adam R; Mary, Pascaline; van Steijn, Volkert; Weitz, David A

2012-04-21

34

In situ Formation of Highly Conducting Covalent Au-C Contacts for Single-Molecule Junctions  

SciTech Connect

Charge transport across metal-molecule interfaces has an important role in organic electronics. Typically, chemical link groups such as thiols or amines are used to bind organic molecules to metal electrodes in single-molecule circuits, with these groups controlling both the physical structure and the electronic coupling at the interface. Direct metal-carbon coupling has been shown through C60, benzene and {pi}-stacked benzene but ideally the carbon backbone of the molecule should be covalently bonded to the electrode without intervening link groups. Here, we demonstrate a method to create junctions with such contacts. Trimethyl tin (SnMe{sub 3})-terminated polymethylene chains are used to form single-molecule junctions with a break-junction technique. Gold atoms at the electrode displace the SnMe{sub 3} linkers, leading to the formation of direct Au-C bonded single-molecule junctions with a conductance that is {approx}100 times larger than analogous alkanes with most other terminations. The conductance of these Au-C bonded alkanes decreases exponentially with molecular length, with a decay constant of 0.97 per methylene, consistent with a non-resonant transport mechanism. Control experiments and ab initio calculations show that high conductances are achieved because a covalent Au-C sigma ({sigma}) bond is formed. This offers a new method for making reproducible and highly conducting metal-organic contacts.

Cheng, Z.L.; Hybertsen, M.; Skouta, R.; Vazquez, H.; Widawsky, J.R.; Schneebeli, S.; Chen, W.; Breslow, R.; Venkataraman, L.

2011-06-01

35

Analysis of USJ formation with combined RTA/laser annealing conditions for 28 nm high-k/metal gate CMOS technology using advanced TCAD for process and device simulation  

NASA Astrophysics Data System (ADS)

TCAD process and device simulations are used to gain physical understanding for the integration of laser-annealed junctions into a 28 nm high-k/metal gate first process flow. Spike-RTA (Rapid Thermal Annealing) scaling used for transient enhanced diffusion (TED) suppression and shallow extension formation is investigated. In order to overcome the performance loss due to a reduced RTA, laser anneal (lsa) is introduced after Spike-RTA to form highly activated and ultra shallow junctions (USJs). In this work, the impact of different annealing conditions on the performance of NMOS and PMOS devices is investigated in terms of Vth and Ion/Ioff, considering lateral dopant diffusion and activation.

Bazizi, E. M.; Zaka, A.; Benistant, F.

2013-05-01

36

Is there evidence for venular large junctional gap formation in inflammation?  

PubMed

Inflammatory edema is associated with vascular macromolecular leakage. Various patterns of vascular macromolecular leakage may be produced depending on the severity and nature of the inflammatory stimulus resulting in transient and/or sustained increases in macromolecular permeability. Inflammatory stimuli which cause endothelial cell damage or destruction induces non-specific increases in macromolecular permeability in all injured microvessels. In the absence of endothelial cell injury, macromolecular permeability is increased in inflammation subsequent to the formation of inter-endothelial cell gaps in capillaries and venules. Various inflammatory mediators including histamine-type agents, immune complexes, and activated leukocytes induce venular large junctional gap formation. Individual, simultaneous, or sequential mediator effects could explain the various patterns of venular macromolecular leakage found in inflammation. The formation of endothelial cell junctional gaps in capillaries cannot be attributed to any known inflammatory mediator. The classical static small pore/large pore model of the microvascular membrane cannot explain the increased extravasation of macromolecules in inflammation. A dual static/variable large pore system would best describe macromolecular transport under normal and inflammatory conditions. PMID:3915340

Grega, G J; Adamski, S W; Svensjo, E

1985-06-01

37

Formation of adherens junctions leads to the emergence of a tissue-level tension in epithelial monolayers  

PubMed Central

ABSTRACT Adherens junctions and desmosomes integrate the cytoskeletons of adjacent cells into a mechanical syncitium. In doing so, intercellular junctions endow tissues with the strength needed to withstand the mechanical stresses encountered in normal physiology and to coordinate tension during morphogenesis. Though much is known about the biological mechanisms underlying junction formation, little is known about how tissue-scale mechanical properties are established. Here, we use deep atomic force microscopy (AFM) indentation to measure the apparent stiffness of epithelial monolayers reforming from dissociated cells and examine which cellular processes give rise to tissue-scale mechanics. We show that the formation of intercellular junctions coincided with an increase in the apparent stiffness of reforming monolayers that reflected the generation of a tissue-level tension. Tension rapidly increased, reaching a maximum after 150?min, before settling to a lower level over the next 3?h as monolayers established homeostasis. The emergence of tissue tension correlated with the formation of adherens junctions but not desmosomes. As a consequence, inhibition of any of the molecular mechanisms participating in adherens junction initiation, remodelling and maturation significantly impeded the emergence of tissue-level tension in monolayers. PMID:24659804

Harris, Andrew R.; Daeden, Alicia; Charras, Guillaume T.

2014-01-01

38

PAR6B is required for tight junction formation and activated PKC? localization in breast cancer  

PubMed Central

Dysregulation of mechanisms that govern the control of epithelial cell polarity, morphology and plasticity are emerging as key processes in tumor progression. In this study we report amplification and overexpression of PAR6B, an essential component in epithelial cell tight junction (TJ) formation and maintenance of apico-basal polarity, in breast cancer cell lines. Analysis of chromosome 20q13.13 in 11 breast cancer cell lines by fluorescence in situ hybridization (FISH) identified a novel small amplicon centered at PARD6B in 5 cell lines, with copy number ranging from 7 to 27. The presence of the PARD6B amplicon correlated with PARD6B transcript and PAR6B protein abundance. Expression of related isoforms PARD6A and PARD6G were detectable at significantly lower levels. PARD6B overexpression correlated with TJ network formation in cultured cell monolayers. SiRNA-mediated inhibition of PAR6B in MCF7 resulted in loss of TJ assembly and membrane localization of atypical PKC? (aPKC), but did not affect adherens junction formation. SiRNA-mediated inhibition of CDC42 in MCF7 also resulted in loss of TJ networks, confirming the requirement of a complete PAR6-aPKC-CDC42-PAR3 complex to activate and stabilize TJs. Immunohistochemical analysis of PAR6B expression on breast tumor microarrays indicated exquisite epithelial cell-specificity. Few quantitative differences in staining were observed between normal epithelium and adjacent tumor margins. However staining appeared reduced and cytoplasmic in more poorly differentiated tumors. We propose that quantitative imbalances in the components of pathways governing normal epithelial cell polarity arising from gain or loss of function may radically alter epithelial cell architecture and contribute to tumor progression. PMID:22957302

Cunliffe, Heather E; Jiang, Yuan; Fornace, Kimberly M; Yang, Fan; Meltzer, Paul S

2012-01-01

39

Estrogen and cyclic amp action, and the involvement of the cytoskeleton on gap junction formation in rat myometrium  

E-print Network

ESTROGEN AND CYCLIC AMP ACTION, ANO THE INVOLVEMENT OF THE CYTOSKELETON ON GAP JUNCTION FORMATION IN RAT MYOMETRIUM A Thesis by OANA GADOY Submitted to the Graduate College of Texas A8M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1985 Major Subject: Zoology ESTROGEN AND CYCLIC ANP ACTION, AND THE INVOLVEHEi4T OF THE CYTOSKELETON ON GAP JUNCTION FORMATION IN RAT HYOMETRIUH A Thesis by DANA GAODY Approved as to style and content by: Ro...

Gaddy, Dana

2012-06-07

40

Afadin Regulates Puncta Adherentia Junction Formation and Presynaptic Differentiation in Hippocampal Neurons  

PubMed Central

The formation and remodeling of mossy fiber-CA3 pyramidal cell synapses in the stratum lucidum of the hippocampus are implicated in the cellular basis of learning and memory. Afadin and its binding cell adhesion molecules, nectin-1 and nectin-3, together with N-cadherin, are concentrated at puncta adherentia junctions (PAJs) in these synapses. Here, we investigated the roles of afadin in PAJ formation and presynaptic differentiation in mossy fiber-CA3 pyramidal cell synapses. At these synapses in the mice in which the afadin gene was conditionally inactivated before synaptogenesis by using nestin-Cre mice, the immunofluorescence signals for the PAJ components, nectin-1, nectin-3 and N-cadherin, disappeared almost completely, while those for the presynaptic components, VGLUT1 and bassoon, were markedly decreased. In addition, these signals were significantly decreased in cultured afadin-deficient hippocampal neurons. Furthermore, the interevent interval of miniature excitatory postsynaptic currents was prolonged in the cultured afadin-deficient hippocampal neurons compared with control neurons, indicating that presynaptic functions were suppressed or a number of synapse was reduced in the afadin-deficient neurons. Analyses of presynaptic vesicle recycling and paired recordings revealed that the cultured afadin-deficient neurons showed impaired presynaptic functions. These results indicate that afadin regulates both PAJ formation and presynaptic differentiation in most mossy fiber-CA3 pyramidal cell synapses, while in a considerable population of these neurons, afadin regulates only PAJ formation but not presynaptic differentiation. PMID:24587018

Toyoshima, Daisaku; Mandai, Kenji; Maruo, Tomohiko; Supriyanto, Irwan; Togashi, Hideru; Inoue, Takahito; Mori, Masahiro; Takai, Yoshimi

2014-01-01

41

Kartogenin induces cartilage-like tissue formation in tendon–bone junction  

PubMed Central

Tendon–bone junctions (TBJs) are frequently injured, especially in athletic settings. Healing of TBJ injuries is slow and is often repaired with scar tissue formation that compromises normal function. This study explored the feasibility of using kartogenin (KGN), a biocompound, to enhance the healing of injured TBJs. We first determined the effects of KGN on the proliferation and chondrogenic differentiation of rabbit bone marrow stromal cells (BMSCs) and patellar tendon stem/progenitor cells (PTSCs) in vitro. KGN enhanced cell proliferation in both cell types in a concentration-dependent manner and induced chondrogenic differentiation of stem cells, as demonstrated by high expression levels of chondrogenic markers aggrecan, collagen II and Sox-9. Besides, KGN induced the formation of cartilage-like tissues in cell cultures, as observed through the staining of abundant proteoglycans, collagen II and osteocalcin. When injected into intact rat patellar tendons in vivo, KGN induced cartilage-like tissue formation in the injected area. Similarly, when KGN was injected into experimentally injured rat Achilles TBJs, wound healing in the TBJs was enhanced, as evidenced by the formation of extensive cartilage-like tissues. These results suggest that KGN may be used as an effective cell-free clinical therapy to enhance the healing of injured TBJs.

Zhang, Jianying; Wang, James H-C

2014-01-01

42

Distinct Roles of Muscle and Motoneuron LRP4 in Neuromuscular Junction Formation  

PubMed Central

SUMMARY Neuromuscular junction (NMJ) formation requires precise interaction between motoneurons and muscle fibers. LRP4 is a receptor of agrin that is thought to act incis to stimulate MuSK in muscle fibers for postsynaptic differentiation. Here we dissected the roles of LRP4 in muscle fibers and motoneurons in NMJ formation by cell-specific mutation. Studies of muscle-specific mutants suggest that LRP4 is involved in deciding where to form AChR clusters in muscle fibers, postsynaptic differentiation, and axon terminal development. LRP4 in HEK293 cells increased synapsin or SV2 puncta in contacting axons of co-cultured neurons, suggesting a synaptogenic function. Analysis of LRP4 muscle and motoneuron double mutants and mechanistic studies suggest that NMJ formation may also be regulated by LRP4 in motoneurons, which could serve as agrin’s receptor in trans to induce AChR clusters. These observations uncovered distinct roles of LRP4 in motoneurons and muscles in NMJ development. PMID:22794264

Wu, Haitao; Lu, Yisheng; Shen, Chengyong; Patel, Neil; Gan, Lin; Xiong, Wen C.; Mei, Lin

2012-01-01

43

Gas-liquid slug formation at a rectangular microchannel T-junction: A CFD benchmark case  

NASA Astrophysics Data System (ADS)

Computational fluid dynamics (CFD) is an important tool for development of microfluidic systems based on gasliquid two-phase flow. The formation of Taylor slugs at microchannel T-junctions has been studied both experimentally and numerically, however discrepancies still exist because of difficulties in correctly representing experimental conditions and uncertainties in the physics controlling slug flow, such as contact line and velocity slip. In this paper detailed methods and results are described for the study of Santos and Kawaji [1] on the comparison of experimental results and numerical modeling. The system studied consisted of a rectangular microchannel Tjunction nominally 100 ?m in hydraulic diameter, used to generate Taylor slugs from air-water perpendicular flow. The effect of flow rates on parameters such as slug length, velocity slip, void fraction and two-phase frictional pressure drop were studied. Numerical simulation was performed using FLUENT volume-of-fluid (VOF) model. It is proposed in this paper that this microfluidic problem be taken up by researchers in the field as a benchmark case to test other numeric codes in comparison to FLUENT on the prediction of micro-scale multiphase flow, and also to model in more detail the experimental system described to obtain greater accuracy in prediction of microfluidic slug formation.

Santos, Rafael M.; Kawaji, Masahiro

2011-12-01

44

Regional changes of AQP0-dependent square array junction and gap junction associated with cortical cataract formation in the Emory mutant mouse.  

PubMed

The Emory mutant mouse has been widely used as an animal model for human senile cataract since it develops late-onset hereditary cataract. Here, we focus on the regional changes of aquaporin-0 (AQP0) and connexins that are associated with the cortical cataract formation in the Emory mutant mice. Emory mutant and CFW wild-type mice at age 1-16 months were used in this study. By using an established photography system with dissecting microscopy, the opacities were first detected at the anterior or posterior lens center surface in Emory mice at age 7 months, and gradually extended toward the equator during the 16 months examined. Scanning EM verified that disorganized and fragmented fiber cells were associated with the areas of opacities within approximately 200 ?m from the lens surface, indicating that Emory mouse cataracts belong to the cortical cataracts. Freeze-fracture TEM further confirmed that cortical cataracts exhibited extensive wavy square array junctions, small gap junctions and globules. Immunofluorescence analysis showed that in contrast to the high labeling intensity of AQP0-loop antibody, the labeling of AQP0 C-terminus antibody was decreased considerably in superficial fibers in Emory cataracts. Similarly, a significant decrease in the labeling of the antibody against Cx50 C-terminus, but not Cx46 C-terminus, occurred in superficial and outer cortical fibers in Emory cataracts. Western blotting further revealed that the C-termini of both AQP0 and Cx50 in Emory cataracts were decreased to over 50% to that of the wild-type. Thus, this systematic study concludes that the Emory mouse cataract belongs to the cortical cataract which is due to regional breakdown of superficial fibers associated with formation of AQP0-dependent wavy square array junctions, small gap junctions and globules. The marked decreases of the C-termini of both AQP0 and Cx50 in the superficial fibers may disturb the needed interaction between these two proteins during fiber cell differentiation and thus play a role in the cortical cataract formation in Emory mutant mice. PMID:25088353

Biswas, Sondip K; Brako, Lawrence; Gu, Sumin; Jiang, Jean X; Lo, Woo-Kuen

2014-10-01

45

Rab35 regulates cadherin-mediated adherens junction formation and myoblast fusion  

PubMed Central

Cadherins are homophilic cell–cell adhesion molecules implicated in many fundamental processes, such as morphogenesis, cell growth, and differentiation. They accumulate at cell–cell contact sites and assemble into large macromolecular complexes named adherens junctions (AJs). Cadherin targeting and function are regulated by various cellular processes, many players of which remain to be uncovered. Here we identify the small GTPase Rab35 as a new regulator of cadherin trafficking and stabilization at cell–cell contacts in C2C12 myoblasts and HeLa cells. We find that Rab35 accumulates at cell–cell contacts in a cadherin-dependent manner. Knockdown of Rab35 or expression of a dominant-negative form of Rab35 impaired N- and M-cadherin recruitment to cell–cell contacts, their stabilization at the plasma membrane, and association with p120 catenin and led to their accumulation in transferrin-, clathrin-, and AP-2–positive intracellular vesicles. We also find that Rab35 function is required for PIP5KI? accumulation at cell–cell contacts and phosphatidyl inositol 4,5-bisphosphate production, which is involved in cadherin stabilization at contact sites. Finally, we show that Rab35 regulates myoblast fusion, a major cellular process under the control of cadherin-dependent signaling. Taken together, these results reveal that Rab35 regulates cadherin-dependent AJ formation and myoblast fusion. PMID:23197472

Charrasse, Sophie; Comunale, Franck; De Rossi, Sylvain; Echard, Arnaud; Gauthier-Rouviere, Cecile

2013-01-01

46

Physical understanding of cryogenic implant benefits for electrical junction stability  

SciTech Connect

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.

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

47

Structural features of aquaporin 4 supporting the formation of arrays and junctions in biomembranes.  

PubMed

A limited class of aquaporins has been described to form regular arrays and junctions in membranes. The biological significance of these structures, however, remains uncertain. Here we analyze the underlying physical principles with the help of a computational procedure that takes into account protein-protein as well as protein-membrane interactions. Experimentally observed array/junction structures are systematically (dis)assembled and major driving forces identified. Aquaporin 4 was found to be markedly different from the non-junction forming aquaporin 1. The environmental stabilization resulting from embedding into the biomembrane was identified as the main driving force. This highlights the role of protein-membrane interactions in aquaporin 4. Analysis of the type presented here can help to decipher the biological role of membrane arrays and junctions formed by aquaporin. PMID:22554469

Höfinger, Siegfried; Yamamoto, Eiji; Hirano, Yoshinori; Zerbetto, Francesco; Narumi, Tetsu; Yasuoka, Kenji; Yasui, Masato

2012-09-01

48

Numerical Study on Taylor Bubble Formation in a Microchannel T-Junction Using VOF Method  

Microsoft Academic Search

A volume of fluid (VOF) method is used to study the immiscible gas–liquid two-phase flow in a microchannel T-junction, through\\u000a which the accurate interface of the Taylor bubble flow inside the micro-channel is captured and compared with visualization\\u000a experiment of Taylor bubbles’ generation inside a T-junction microfluidic chip. The numerical results are in good agreement\\u000a with the experimental measurements, which

Fang Guo; Bin Chen

2009-01-01

49

Arc/Forearc Lengthening at Plate Triple Junctions and the Formation of Ophiolitic Soles  

NASA Astrophysics Data System (ADS)

The principal enigma of large obducted ophiolite slabs is that they clearly must have been generated by some form of organized sea-floor spreading/plate-accretion, such as may be envisioned for the oceanic ridges, yet the volcanics commonly have arc affinity (Miyashiro) with boninites (high-temperature/low-pressure, high Mg and Si andesites), which are suggestive of a forearc origin. PT conditions under which boninites and metamorphic soles form and observations of modern forearc systems lead us to the conclusion that ophiolite formation is associated with overidding plate spreading centers that intersect the trench to form ridge-trench-trench of ridge-trench-tranform triple junctions. The spreading centers extend and lengthen the forearc parallel to the trench and by definition are in supra-subduction zone (SSZ) settings. Many ophiolites likewise have complexly-deformed associated mafic-ultramafic assemblages that suggest fracture zone/transform t along their frontal edges, which in turn has led to models involving the nucleation of subduction zones on fracture zones or transpressional transforms. Hitherto, arc-related sea-floor-spreading has been considered to be either pre-arc (fore-arc boninites) or post-arc (classic Karig-style back arc basins that trench-parallell split arcs). Syn-arc boninites and forearc oceanic spreading centers that involve a stable ridge/trench/trench triple or a ridge-trench-transform triple junction, the ridge being between the two upper plates, are consistent with large slab ophiolite formation in a readied obduction settting. The direction of subduction must be oblique with a different sense in the two subduction zones and the oblique subduction cannot be partitioned into trench orthogonal and parallel strike-slip components. As the ridge spreads, new oceanic lithosphere is created within the forearc, the arc and fore-arc lengthen significantly, and a syn-arc ophiolite forearc complex is generated by this mechanism. The ophiolite ages along arc-strike; a distinctive diachronous MORB-like to boninitic to arc volcanic stratigraphy develops vertically in the forearc and eruption centers progressively migrate from the forearc back to the main arc massif with time. Dikes in the ophiolite are highly oblique to the trench (as are back-arc magnetic anomalies. Boninites and high-mg andesites are generated in the fore-arc under the aqueous, low pressure/high temperature, regime at the ridge above the instantaneously developed subducting and dehydrating slab. Subducted slab refrigeration of the hanging wall ensues and accretion of MORB metabasites to the hanging wall of the subduction channel initiates. Mafic protolith garnet/two pyroxene granulites to greenschists accrete and form the inverted P and T metamorphic sole prior to obduction. Sole accretion of lithosphere begins at about 1000°C and the full retrogressive sole may be fully formed within ten to fifteen million years of accretion, at which time low grade subduction melanges accrete. Obduction of the SSZ forearc ophiolite with its subjacent metamorphic sole occurs whenever the oceanic arc attempts subduction of a stable buoyant continental or back arc margin.

Casey, John; Dewey, John

2013-04-01

50

Focused Ion Beam Process for Formation of a Metal/Insulator/Metal Double Tunnel Junction  

NASA Astrophysics Data System (ADS)

An improved method to fabricate a small lateral double tunnel junction which utilizes focused ion beam (FIB) etching and lift-off techniques is proposed. A double layer resist consisting of nitrocellulose and germanium layers was used. Narrow grooves with widths comparable to or narrower than the FIB diameter were formed in a ferromagnetic layer of Ni, and Ni/Ni-oxide/Au/Ni-oxide/Ni and Al/Al-oxide/Ni/Al-oxide/Al double junction structures were fabricated using the proposed method. The measured voltage and current characteristics of the latter structures indicated that double tunnel junctions with a barrier height of 0.61 eV were fabricated and suggest that this is a promising method to fabricate island structures for devices utilizing Coulomb blockade or spin blockade effects.

Nakayama, Masayoshi; Yanagisawa, Junichi; Wakaya, Fujio; Gamo, Kenji

1999-12-01

51

Electrical current-driven pinhole formation and insulator-metal transition in tunnel junctions  

Microsoft Academic Search

Current Induced Resistance Switching (CIS) was recently observed in thin tunnel junctions (TJs) with ferromagnetic (FM) electrodes and attributed to electromigration of metallic atoms in nanoconstrictions in the insulating barrier. The CIS effect is here studied in TJs with two thin (20 \\\\AA) non-magnetic (NM) Ta electrodes inserted above and below the insulating barrier. We observe resistance (R) switching for

J. Ventura; Z. Zhang; Y. Liu; J. B. Sousa; P. P. Freitas

2007-01-01

52

New insights into charge extraction and formation of the band-bending region in Schottky junction organic solar cells  

NASA Astrophysics Data System (ADS)

Schottky junction organic solar cells were recently introduced and have demonstrated surprising performance with high open circuit voltage and short circuit current. In this study, the formation of the band bending region and charge extraction from the donor molecules in C60 and C70 based Schottky junction solar cells are investigated. Band bending was observed when the ITO anode was treated with CF4O2 and O2 plasma. These cells demonstrated similar performance to cells with MoO3 coated ITO, which are more common in literature. The presence of donor material at the anode interface was also found to decrease the open circuit voltage of the cell by decreasing the number of fullerene molecules at the anode and consequently, decreasing the extent of band bending. The short-circuit current of the Schottky junction solar cells increased when a thin layer of neat fullerene was introduced between the ITO anode and the donor doped mixed layer by reducing exciton quenching at the anode interface. Finally, hole extraction from the donor was found to be efficient up to 5 nm away from the anode interface. If donor molecules were placed beyond this distance the fill factor dropped precipitously along with the overall cell efficiency.

Sutty, Sibi; Williams, Graeme; Aziz, Hany

2013-10-01

53

The SARS coronavirus E protein interacts with PALS1 and alters tight junction formation and epithelial morphogenesis.  

PubMed

Intercellular tight junctions define epithelial apicobasal polarity and form a physical fence which protects underlying tissues from pathogen invasions. PALS1, a tight junction-associated protein, is a member of the CRUMBS3-PALS1-PATJ polarity complex, which is crucial for the establishment and maintenance of epithelial polarity in mammals. Here we report that the carboxy-terminal domain of the SARS-CoV E small envelope protein (E) binds to human PALS1. Using coimmunoprecipitation and pull-down assays, we show that E interacts with PALS1 in mammalian cells and further demonstrate that the last four carboxy-terminal amino acids of E form a novel PDZ-binding motif that binds to PALS1 PDZ domain. PALS1 redistributes to the ERGIC/Golgi region, where E accumulates, in SARS-CoV-infected Vero E6 cells. Ectopic expression of E in MDCKII epithelial cells significantly alters cyst morphogenesis and, furthermore, delays formation of tight junctions, affects polarity, and modifies the subcellular distribution of PALS1, in a PDZ-binding motif-dependent manner. We speculate that hijacking of PALS1 by SARS-CoV E plays a determinant role in the disruption of the lung epithelium in SARS patients. PMID:20861307

Teoh, Kim-Tat; Siu, Yu-Lam; Chan, Wing-Lim; Schlüter, Marc A; Liu, Chia-Jen; Peiris, J S Malik; Bruzzone, Roberto; Margolis, Benjamin; Nal, Béatrice

2010-11-15

54

Fully-depleted Ge interband tunnel transistor: Modeling and junction formation  

Microsoft Academic Search

Complementary fully-depleted Ge interband-tunneling field-effect transistors (TFETs) and static inverters are modeled to quantify TFET performance relative to Si MOSFETs. SYNOPSYS TCAD is used to compute the two-dimensional electrostatics and determine the tunnel junction electric field. This electric field is used in an analytic expression to compute the tunnel current. The speed and power performance of TFETs are compared with

Qin Zhang; Surajit Sutar; Thomas Kosel; Alan Seabaugh

2009-01-01

55

Junction formation of Cu3BiS3 investigated by Kelvin probe force microscopy and surface photovoltage measurements  

PubMed Central

Summary Recently, the compound semiconductor Cu3BiS3 has been demonstrated to have a band gap of ~1.4 eV, well suited for photovoltaic energy harvesting. The preparation of polycrystalline thin films was successfully realized and now the junction formation to the n-type window needs to be developed. We present an investigation of the Cu3BiS3 absorber layer and the junction formation with CdS, ZnS and In2S3 buffer layers. Kelvin probe force microscopy shows the granular structure of the buffer layers with small grains of 20–100 nm, and a considerably smaller work-function distribution for In2S3 compared to that of CdS and ZnS. For In2S3 and CdS buffer layers the KPFM experiments indicate negatively charged Cu3BiS3 grain boundaries resulting from the deposition of the buffer layer. Macroscopic measurements of the surface photovoltage at variable excitation wavelength indicate the influence of defect states below the band gap on charge separation and a surface-defect passivation by the In2S3 buffer layer. Our findings indicate that Cu3BiS3 may become an interesting absorber material for thin-film solar cells; however, for photovoltaic application the band bending at the charge-selective contact has to be increased. PMID:22497001

Mesa, Fredy; Chamorro, William; Vallejo, William; Baier, Robert; Dittrich, Thomas; Grimm, Alexander; Lux-Steiner, Martha C

2012-01-01

56

Moleskin is essential for the formation of the myotendinous junction in Drosophila  

PubMed Central

It is the precise connectivity between skeletal muscles and their corresponding tendon cells to form a functional myotendinous junction (MTJ) that allows for the force generation required for muscle contraction and organismal movement. The Drosophila MTJ is comprised of secreted extracellular matrix (ECM) proteins deposited between integrin-mediated hemi-adherens junctions on the surface of muscle and tendon cells. In this paper, we have identified a novel, cytoplasmic role for the canonical nuclear import protein Moleskin (Msk) in Drosophila embryonic somatic muscle attachment. Msk protein is enriched at muscle attachment sites in late embryogenesis and msk mutant embryos exhibit a failure in muscle-tendon cell attachment. Although the muscle-tendon attachment sites are reduced in size, components of the integrin complexes and ECM proteins are properly localized in msk mutant embryos. However, msk mutants fail to localize phosphorylated Focal adhesion kinase (pFAK) to the sites of muscle-tendon cell junctions. In addition, the tendon cell specific proteins Stripe (Sr) and activated mitogen-activated protein kinase (MAPK) are reduced in msk mutant embryos. Our rescue experiments demonstrate that Msk is required in the muscle cell, but not in the tendon cells. Moreover, muscle attachment defects due to loss of Msk are rescued by an activated form of MAPK or the secreted Epidermal Growth Factor receptor (Egfr) ligand Vein. Taken together, these findings provide strong evidence that Msk signals non-autonomously through the Vein-Egfr signaling pathway for late tendon cell late differentiation and/or maintenance. PMID:21925492

Liu, Ze (Cindy); Geisbrecht, Erika R.

2014-01-01

57

Planar Be-implanted GaAs junction formation using swept-line electron beam annealing  

SciTech Connect

Comparative studies of swept-line electron beam annealing and furnace annealing of Be implanted in n-GaAs doped with Si are presented. Electron beam annealing causes less Be redistribution and results in fewer traps than furnace annealing, but causes site mixing of amphoteric Si. Planar Be-implanted junctions result in a p(+)-nu-n structure for the electron beam annealed samples, similar to thermally quenched samples. It is believed that this is caused by the incorporation of amphoteric Si on Ga and As sites during transient annealing, which produces results similar to thermal quenching. 14 references.

Banerjee, S.K.; De Jule, R.Y.; Soda, K.J.

1983-12-01

58

In-plane epitaxial growth of silicon nanowires and junction formation on si(100) substrates.  

PubMed

Growing self-assembled silicon nanowires (SiNWs) into precise locations represents a critical capability to scale up SiNW-based functionalities. We here report a novel epitaxy growth phenomenon and strategy to fabricate orderly arrays of self-aligned in-plane SiNWs on Si(100) substrates following exactly the underlying crystallographic orientations. We observe also a rich set of distinctive growth dynamics/modes that lead to remarkably different morphologies of epitaxially grown SiNWs/or grains under variant growth balance conditions. High-resolution transmission electron microscopy cross-section analysis confirms a coherent epitaxy (or partial epitaxy) interface between the in-plane SiNWs and the Si(100) substrate, while conductive atomic force microscopy characterization reveals that electrically rectifying p-n junctions are formed between the p-type doped in-plane SiNWs and the n-type c-Si(100) substrate. This in-plane epitaxy growth could provide an effective means to define nanoscale junction and doping profiles, providing a basis for exploring novel nanoelectronics. PMID:25343717

Yu, Linwei; Xu, Mingkun; Xu, Jie; Xue, Zhaoguo; Fan, Zheng; Picardi, Gennaro; Fortuna, Franck; Wang, Junzhuan; Xu, Jun; Shi, Yi; Chen, Kunji; Roca I Cabarrocas, Pere

2014-11-12

59

Formation of cristae and crista junctions in mitochondria depends on antagonism between Fcj1 and Su e/g  

PubMed Central

Crista junctions (CJs) are important for mitochondrial organization and function, but the molecular basis of their formation and architecture is obscure. We have identified and characterized a mitochondrial membrane protein in yeast, Fcj1 (formation of CJ protein 1), which is specifically enriched in CJs. Cells lacking Fcj1 lack CJs, exhibit concentric stacks of inner membrane in the mitochondrial matrix, and show increased levels of F1FO–ATP synthase (F1FO) supercomplexes. Overexpression of Fcj1 leads to increased CJ formation, branching of cristae, enlargement of CJ diameter, and reduced levels of F1FO supercomplexes. Impairment of F1FO oligomer formation by deletion of its subunits e/g (Su e/g) causes CJ diameter enlargement and reduction of cristae tip numbers and promotes cristae branching. Fcj1 and Su e/g genetically interact. We propose a model in which the antagonism between Fcj1 and Su e/g locally modulates the F1FO oligomeric state, thereby controlling membrane curvature of cristae to generate CJs and cristae tips. PMID:19528297

Rabl, Regina; Soubannier, Vincent; Scholz, Roland; Vogel, Frank; Mendl, Nadine; Vasiljev-Neumeyer, Andreja; Korner, Christian; Jagasia, Ravi; Keil, Thomas; Baumeister, Wolfgang; Cyrklaff, Marek; Neupert, Walter

2009-01-01

60

Four-way junction formation promoting ultrasensitive electrochemical detection of microRNA.  

PubMed

MicroRNAs (miRNAs) represent a class of biomarkers that are frequently deregulated in cancer cells and have shown a great promise for cancer classification and prognosis. Here, we endeavored to develop a DNA four-way junction based electrochemical sensor (4J-SENS) for ultrasensitive miRNA analysis. The developed sensor can be operated within the dynamic range from 10 aM to 1 fM and detect as low as 2 aM of miR-122 (?36 molecules per sample), without PCR amplification. Furthermore, the 4J-SENS was employed to profile endogenouse hsa-miR-122 in healthy human and chronic lymphocyitc leukemia (CLL) patient serum, and the results were validated by qPCR analysis. PMID:24047131

Labib, Mahmoud; Ghobadloo, Shahrokh M; Khan, Nasrin; Kolpashchikov, Dmitry M; Berezovski, Maxim V

2013-10-15

61

Involvement of YAP, TAZ and HSP90 in Contact Guidance and Intercellular Junction Formation in Corneal Epithelial Cells  

PubMed Central

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 TGF?). 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 TGF?2 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 TGF?2 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 ?-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. PMID:25290150

Morgan, Joshua T.; Tuyen, Binh C.; Rose, Brad W.; Reilly, Christopher M.; Russell, Paul; Murphy, Christopher J.

2014-01-01

62

Effect of annealing temperature on formation of superparamagnetism in CoFeB/MgO/CoFeB magnetic tunnel junctions  

NASA Astrophysics Data System (ADS)

We report the annealing effect of CoFeB/MgO/CoFeB magnetic tunnel junctions with a thin free layer. For the junctions with CoFeB free layer below the critical thickness, the MR transfer curves are always hysteresis-free and TMR ratio decreases with increasing annealing temperature. For the junctions with CoFeB free layer above the critical thickness, with increasing annealing temperature, both TMR ratio and coercivity increase firstly and then decrease, and finally hysteresis-free MR transfer curves are obtained. The MR loops without hysteresis can be well fitted by using the Langevin equation, suggesting the formation of superparamagnetic particles in the free layer during the high temperature annealing. This behavior originates from the transformation of the ultra-thin CoFeB free layer during annealing: crystallization process of CoFeB and diffusion at MgO/CoFeB and CoFeB/Ru interfaces.

Cao, Jiangwei; Liu, Yan; Ren, Yang; Wei, Fulin; Freitas, P. P.

2014-09-01

63

Nectin-4 mutations causing ectodermal dysplasia with syndactyly perturb the rac1 pathway and the kinetics of adherens junction formation.  

PubMed

Defective nectin-1 and -4 have been implicated in ectodermal dysplasia (ED) syndromes with variably associated features including orofacial and limb defects. In particular, nectin-1 mutations cause cleft lip/palate ED (CLPED1; OMIM#225060), whereas defective nectin-4 is associated with ED-syndactyly syndrome (EDSS1; OMIM#613573). Although the broad phenotypic overlap suggests a common mode of action of nectin-1 and -4, little is known about the pathogenic mechanisms involved. We report the identification of, to our knowledge, a previously undescribed nectin-4 homozygous p.Val242Met missense mutation in a patient with EDSS1. We used patient skin biopsy and primary keratinocytes, as well as nectin-4 ectopic expression in epithelial cell lines, to characterize functional consequences of p.Val242Met and p.Thr185Met mutations, the latter previously identified in compound heterozygosity with a truncating mutation. We show that nectin-4-altered expression perturbs nectin-1 clustering at keratinocyte contact sites and delays, but does not impede cell-cell aggregation and cadherin recruitment at adherens junctions (AJs). Moreover, trans-interaction of nectin-1 and -4 induces the activation of Rac1, a member of the Rho family of small GTPases, and regulates E-cadherin-mediated cell-cell adhesion. These data outline a synergistic action of nectin-1 and -4 in the early steps of AJ formation and implicate this interaction in modulating the Rac1 signaling pathway. PMID:24577405

Fortugno, Paola; Josselin, Emmanuelle; Tsiakas, Konstantinos; Agolini, Emanuele; Cestra, Gianluca; Teson, Massimo; Santer, René; Castiglia, Daniele; Novelli, Giuseppe; Dallapiccola, Bruno; Kurth, Ingo; Lopez, Marc; Zambruno, Giovanna; Brancati, Francesco

2014-08-01

64

Metrology and High Resolution Mapping of Shallow Junctions Formed by Low Energy Implant Processes  

NASA Astrophysics Data System (ADS)

This paper presents results obtained using a Junction Photo-Voltage (JPV) method optimized for characterization of the combined implant-annealing process. The tool was found to be particularly suited to measurement of ultra-shallow junction sheet resistivity and leakage. In this work the authors also evaluated the benefits of improved spatial resolution compared to previous equipment designs. Current technology USJ monitor wafers were made using a BF2 or Arsenic implant followed by a spike anneal and also R&D USJ wafers were made by Plasma Immersion followed by laser annealing. All the wafers were measured using the non-contact JPV measurement tool. Results obtained from the JPV measurements were correlated to destructive off-line analytical measurement tools.

Don, Eric; Pap, Aron; Tutto, Peter; Pavelka, Tibor; Wyon, Christophe; Laviron, Cyrille; Sotta, David; Oechsner, Richard; Pfeffer, Marcus

2006-11-01

65

One step sol–gel method for the formation of etch free texturing, anti-reflection coatings, and p–n junction for silicon solar cells  

Microsoft Academic Search

This study evaluated one step sol–gel process for the simultaneous formation of surface texturing without a series of chemical etching processes, as well as anti-reflection coatings without complicated vacuum processes and p–n junctions. The solutions for this process were prepared from a proper combination of precursors containing phosphorus and nano-size silicon dioxide particles. The specimen heat treated at 1000°C showed

H. J. Bae; S. M. Kang; T. S. Kim; D. H. Yoon

2011-01-01

66

Massive formation of square array junctions dramatically alters cell shape but does not cause lens opacity in the cav1-KO mice.  

PubMed

The wavy square array junctions are composed of truncated aquaporin-0 (AQP0) proteins typically distributed in the deep cortical and nuclear fibers in wild-type lenses. These junctions may help maintain the narrowed extracellular spaces between fiber cells to minimize light scattering. Herein, we investigate the impact of the cell shape changes, due to abnormal formation of extensive square array junctions, on the lens opacification in the caveolin-1 knockout mice. The cav1-KO and wild-type mice at age 1-22 months were used. By light microscopy examinations, cav1-KO lenses at age 1-18 months were transparent in both cortical and nuclear regions, whereas some lenses older than 18 months old exhibited nuclear cataracts. Scanning EM consistently observed the massive formation of ridge-and-valley membrane surfaces in young fibers at approximately 150 ?m deep in all cav1-KO lenses studied. In contrast, the typical ridge-and-valleys were only seen in mature fibers deeper than 400 ?m in wild-type lenses. The resulting extensive ridge-and-valleys dramatically altered the overall cell shape in cav1-KO lenses. Remarkably, despite dramatic shape changes, these deformed fiber cells remained intact and made close contact with their neighboring cells. By freeze-fracture TEM, ridge-and-valleys exhibited the typical orthogonal arrangement of 6.6 nm square array intramembrane particles and displayed the narrowed extracellular spaces. Immunofluorescence analysis showed that AQP0 C-terminus labeling was significantly decreased in outer cortical fibers in cav1-KO lenses. However, freeze-fracture immunogold labeling showed that the AQP0 C-terminus antibody was sparsely distributed on the wavy square array junctions, suggesting that the cleavage of AQP0 C-termini might not yet be complete. The cav1-KO lenses with nuclear cataracts showed complete cellular breakdown and large globule formation in the lens nucleus. This study suggests that despite dramatic cell shape changes, the massive formation of wavy square array junctions in intact fibers may provide additional adhesive support for maintaining the narrowed extracellular spaces that are crucial for the transparency of cav1-KO lenses. PMID:24877741

Biswas, Sondip K; Brako, Lawrence; Lo, Woo-Kuen

2014-08-01

67

The Apical Junctional Complex in Respiratory Diseases  

PubMed Central

The epithelium, including the respiratory system, acts as a selective gate between the outside environment and underlying tissue. Epithelial cells are polarized due to the formation of the apical junctional complex, which includes adherent junctions and tight junctions. Endothelial cells are one of the most important cellular constituents of blood vessels. Endothelial junctional proteins play important roles in tissue integrity as well as in vascular permeability, leukocyte extravasation, and angiogenesis. This review focuses on the apical junctional complex in respiratory diseases. PMID:24855600

2014-01-01

68

Combined evaluation of grazing incidence X-ray fluorescence and X-ray reflectivity data for improved profiling of ultra-shallow depth distributions  

NASA Astrophysics Data System (ADS)

The continuous downscaling of the process size for semiconductor devices pushes the junction depths and consequentially the implantation depths to the top few nanometers of the Si substrate. This motivates the need for sensitive methods capable of analyzing dopant distribution, total dose and possible impurities. X-ray techniques utilizing the external reflection of X-rays are very surface sensitive, hence providing a non-destructive tool for process analysis and control. X-ray reflectometry (XRR) is an established technique for the characterization of single- and multi-layered thin film structures with layer thicknesses in the nanometer range. XRR spectra are acquired by varying the incident angle in the grazing incidence regime while measuring the specular reflected X-ray beam. The shape of the resulting angle-dependent curve is correlated to changes of the electron density in the sample, but does not provide direct information on the presence or distribution of chemical elements in the sample. Grazing Incidence XRF (GIXRF) measures the X-ray fluorescence induced by an X-ray beam incident under grazing angles. The resulting angle dependent intensity curves are correlated to the depth distribution and mass density of the elements in the sample. GIXRF provides information on contaminations, total implanted dose and to some extent on the depth of the dopant distribution, but is ambiguous with regard to the exact distribution function. Both techniques use similar measurement procedures and data evaluation strategies, i.e. optimization of a sample model by fitting measured and calculated angle curves. Moreover, the applied sample models can be derived from the same physical properties, like atomic scattering/form factors and elemental concentrations; a simultaneous analysis is therefore a straightforward approach. This combined analysis in turn reduces the uncertainties of the individual techniques, allowing a determination of dose and depth profile of the implanted elements with drastically increased confidence level. Silicon wafers implanted with Arsenic at different implantation energies were measured by XRR and GIXRF using a combined, simultaneous measurement and data evaluation procedure. The data were processed using a self-developed software package (JGIXA), designed for simultaneous fitting of GIXRF and XRR data. The results were compared with depth profiles obtained by Secondary Ion Mass Spectrometry (SIMS).

Ingerle, D.; Meirer, F.; Pepponi, G.; Demenev, E.; Giubertoni, D.; Wobrauschek, P.; Streli, C.

2014-09-01

69

High-T(sub c) Superconductor-Normal-Superconductor Junctions with Polyimide-Passivated Ambient Temperature Edge Formation  

NASA Technical Reports Server (NTRS)

The ability to controllably fabricate High-Temperature Superconductor (HTS) S-Normal-S (SNS) Josephson Juntions (JJ's) enhances the possibilities fro many applications, including digital circuits, SQUID's, and mixers. A wide variety of approaches to fabricating SNS-like junctions has been tried and analyzed in terms of proximity effect behavior.

Barner, J. B.; Kleinsasser, A. W.; Hunt, B. D.

1996-01-01

70

In situ formation of p-n junction: a novel principle for photoelectrochemical sensor and its application for mercury(II) ion detection.  

PubMed

The discovery and development of photoelectrochemical sensors with novel principles are of great significance to realize sensitive and low-cost detection. In this paper, a new photoelectrochemial sensor based on the in situ formation of p-n junction was designed and used for the accurate determination of mercury(II) ions. Cysteine-capped ZnS quantum dots (QDs) was assembled on the surface of indium tin oxide (ITO) electrode based on the electrostatic interaction between Poly(diallyldimethylammonium chloride) (PDDA) and Cys-capped ZnS QDs. The in situ formation of HgS, a p-type semiconductor, on the surface of ZnS facilitated the charge carrier transport and promoted electron-hole separation, triggered an obviously enhanced anodic photocurrent of Cys-capped ZnS QDs. The formation of p-n junction was confirmed by P-N conductive type discriminator measurements and current-voltage (I-V) curves. The photoelectrochemical method was used for the sensing of trace mercuric (II) ions with a linear concentration of 0.01 to 10.0 µM and a detection limit of 4.6×10(-9)mol/L. It is expected that the present study can serve as a foundation to the application of p-n heterojunction to photoelectrochemical sensors and it might be easily extended to more exciting sensing systems by photoelectrochemistry. PMID:24832992

Wang, Guang-Li; Liu, Kang-Li; Dong, Yu-Ming; Li, Zai-Jun; Zhang, Chi

2014-05-27

71

Ultrastructural studies on neuromuscular contacts and the formation of junctions in the flight muscle of Antheraea polyphemus (Lep.) I. Normal adult development.  

PubMed

The ultrastructure of neuromuscular connections on developing dorsolongitudinal flight muscles were studied in the moth Antheraea polyphemus. Undifferentiated membrane contacts between axon terminals and muscle-fiber anlagen are present in the diapause pupa. They persist during the period of nerve outgrowth, which probably provides a pathway of contact guidance. By the 4th day of adult development some of these contact areas have differentiated into structures similar to neuromuscular junctions although differentiation of muscle structure does not start earlier than the eighth day. Dense-cored vesicles are abundant in many axon terminals at the beginning of development. They later decrease in number quite rapidly. The significance of the above-mentioned early junctions, their possible mode of action and the role of the dense-cored vesicles are discussed. It is proposed that they exercise a stimulating (trophic) influence on the growth of the undifferentiated muscular tissue. The imaginal neuromuscular junctions are formed during the second half of adult development. Clusters of vesicles and electron-dense depositions along the inner face of the axo- and lemma seem to initiate junction formation. Glial processes then grow between the axo- and sarcolemma and divide the large contact area into several small segments. Mutual invaginations and protrusions of the sarcolemma and the glial cell membrane subsequently form an extensive "rete synapticum." Six days before eclosion the glial and sarcoplasmic parts of the rete synapticum are similar in size. Up to eclosion, all glial processes shrink and increase in electron density. Most of the observations are discussed also in relation to findings in vertebrates. PMID:1149098

Stocker, R F; Nüesch, H

1975-06-01

72

A Model for Central Synaptic Junctional Complex Formation Based on the Differential Adhesive Specificities of the Cadherins  

Microsoft Academic Search

Cadherins control critical developmental events through well-documented homophilic interactions. In epithelia, they are hallmark constituents of junctions that mediate intercellular adhesion. Brain tissue expresses several cadherins, and we now show that two of these, neural (N)- and epithelial (E)-cadherin, are localized to synaptic complexes in mutually exclusive distributions. In cerebellum, N-cadherin is frequently found associated with synapses, some of which

Allison M Fannon; David R Colman

1996-01-01

73

Altered ?-defensin 5 expression in cervical squamocolumnar junction: implication in the formation of a viral/tumour-permissive microenvironment.  

PubMed

Human papillomavirus (HPV) infection, particularly type 16, is causally associated with cancer of the uterine cervix, which mainly develops at the squamocolumnar (SC) junction. The progression of cervical HPV infections into (pre)neoplastic lesions suggests that viral antigens are not adequately recognized by innate immunity or presented to the adaptive immune system. Members of the defensin family have recently been found to inhibit viral and bacterial pathogens, to stimulate the migration of immune cells and to play a role in anticancer responses. In the present study, we focused on the poorly characterized human ?-defensin 5 (HD-5) and its possible role in these processes. We showed that HD-5 was able to prevent HPV virion entry into cervical keratinocytes and to influence adaptive immunity. Indeed, this peptide specifically induced the chemoattraction and proliferation of both activated T lymphocytes and immature dendritic cells in a CCR2/CCR6-dependent manner and stimulated the infiltration of these professional antigen-presenting cells in a (pre)neoplastic epithelium transplanted in vivo in immunodeficient mice. No chemotactic effect was observed with plasmacytoid dendritic cells, macrophages or natural killer cells. Proliferative and angiogenic effects of HD-5 were also assessed in vitro and in vivo. However there was a striking regional disparity in expression of HD-5, being prominent in ectocervical, vaginal and vulvar neoplasia, while absent, or nearly so, in the cervical SC junction. Taken together, these results suggest one possible explanation for why the SC junction is uniquely vulnerable to both high-risk HPV infection (via reduced HD-5 expression and viral entry) and progression of neoplasia (via altered cell-mediated immune responses and altered microenvironment). Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. PMID:25196670

Hubert, Pascale; Herman, Ludivine; Roncarati, Patrick; Maillard, Catherine; Renoux, Virginie; Demoulin, Stéphanie; Erpicum, Charlotte; Foidart, Jean-Michel; Boniver, Jacques; Noël, Agnès; Delvenne, Philippe; Herfs, Michael

2014-12-01

74

On the formation and evolution of the Pannonian Basin: Constraints derived from the structure of the junction area between the Carpathians and Dinarides  

NASA Astrophysics Data System (ADS)

The large number and distribution of rollback systems in Mediterranean orogens infer the possibility of interacting extensional back-arc deformation driven by different slabs. The formation of the Pannonian back-arc basin is generally related to the rapid Miocene rollback of a slab attached to the European continent. A key area of the entire system that is neglected by kinematic studies is the connection between the South Carpathians and Dinarides. In order to derive an evolutionary model, we interpreted regional seismic lines traversing the entire Serbian part of the Pannonian Basin. The observed deformation is dominantly expressed by the formation of Miocene extensional detachments and (half) grabens. The extensional geometries and associated synkinematic sedimentation that migrated in time and space allow the definition of a continuous and essentially asymmetric early to late Miocene extensional evolution. This evolution was followed by the formation of few uplifted areas during the subsequent latest Miocene-Quaternary inversion. The present-day extensional geometry changing the strike across the basin is an effect of the clockwise rotation of the South Carpathians and Apuseni Mountains in respect to the Dinarides. Our study infers that the Carpathian rollback is not the only mechanism responsible for the formation of the Pannonian Basin; an additional middle Miocene rollback of a Dinaridic slab is required to explain the observed structures. Furthermore, the study provides constraints for the pre-Neogene orogenic evolution of this junction zone, including the affinity of major crustal blocks, obducted ophiolitic sequences and the Sava suture zone.

Matenco, L.; Radivojevi?, D.

2012-12-01

75

Effects of junction formation conditions on the photovoltaic properties of sintered CdS/CdTe solar cells  

NASA Astrophysics Data System (ADS)

The microstructure and electrical properties of sintered CdS/CdTe heterojunction solar cells were examined experimentally. Borosilicate glass substrates were coated with a slurry of calcined CdS, and the combination was sintered at 650 C for an hour. The resulting films were coated with a CdTe slurry to a thickness of 25 microns and the combinations were sintered at temperatures ranging from 585-700 C. The CdS films had grain sizes averaging 15 microns while the CdTe grains averaged just over 5 microns. The sintering process produced p-n junctions. A maximum solar cell efficiency of 7.18 percent was obtained when the final sintering was 625 C for 1 hr. Effective cells were only obtained when the sintering temperature was between 610-625 C.

Lee, J. S.; Im, H. B.

1986-03-01

76

A model for central synaptic junctional complex formation based on the differential adhesive specificities of the cadherins.  

PubMed

Cadherins control critical developmental events through well-documented homophilic interactions. In epithelia, they are hallmark constituents of junctions that mediate intercellular adhesion. Brain tissue expresses several cadherins, and we now show that two of these, neural (N)- and epithelial (E)-cadherin, are localized to synaptic complexes in mutually exclusive distributions. In cerebellum, N-cadherin is frequently found associated with synapses, some of which are perforated, and in hippocampus, N- and E-cadherin-containing synapses are found aligned along dendritic shafts within the stratum lucidum of CA3. We propose that the cadherins function as primary adhesive moieties between pre- and postsynaptic membranes in the synaptic complex. According to this model, once neurites have been guided to the vicinity of their cognate targets, it is the differential distribution of cadherins along the axonal and dendritic plasma membranes, and ultimately cadherin self-association, that "locks in" nascent synaptic connections. PMID:8816706

Fannon, A M; Colman, D R

1996-09-01

77

Fabrication of hexagonally packed cell culture substrates using droplet formation in a T-shaped microfluidic junction  

PubMed Central

A method is here proposed to fabricate ordered hexagonally packed cell culture substrates with hexagonally arranged cell patterning areas. We generated photo-sensitive polymeric microdroplets in a T-shaped microfluidic junction by an immiscible liquid, and then solidified the collective self-assembled hexagonal droplet array to obtain the cell culture substrate, on which we took the grooves formed between the solidified droplets as the hexagonally arranged cell patterning areas. The most promising advantage of our method is that we can actively tune the droplet size by simply adopting different volumetric flow rates of the two immiscible fluids to form cell culture substrates with differently sized cell patterning areas. Besides, the examination results of the cell culture substrate's characteristics validate whether our method is capable of creating substrates with high spatial uniformity. To verify the cell patterning function of our cell culture substrates, we used the semi-adherent RAW cells to demonstrate the effectiveness of patterning of suspended/adherent cells before/after adhesion. Over 90% cell viability and cell patterning rate suggest that our method may be a promising approach for future applications of cell patterning on biochips. PMID:24396524

Peng Lee, Chiun; Hsin Chen, Yi; Hang Wei, Zung

2013-01-01

78

A Cell Motility Screen Reveals Role for MARCKS-Related Protein in Adherens Junction Formation and Tumorigenesis  

Microsoft Academic Search

Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

Alexander E. Finlayson; Kevin W. Freeman; Juha Klefstrom

2009-01-01

79

Hemicentin 2 and Fibulin 1 are required for epidermal-dermal junction formation and fin mesenchymal cell migration during zebrafish development  

PubMed Central

Summary Hemicentin 1 (Hmcn1) and Hemicentin 2 (Hmcn2) belong to the fibulin family of extracellular matrix (ECM) proteins that play pivotal roles during development and homeostasis of a variety of vertebrate tissues. Recently, we have shown that mutations in zebrafish Hmcn1, also called Fibulin 6, lead to massive fin blistering, similar to the defects caused by the Fraser syndrome gene Fras1. In contrast, the role of Hmcn2 during vertebrate development has thus far been uncharacterized. In zebrafish, hmcn2, like fibulin 1 (fbln1), another member of the fibulin family, is predominantly expressed in fin mesenchymal cells and developing somites, contrasting the strict epithelial expression of hmcn1. While antisense morpholino oligonucleotide (MO) – based knockdown of hmcn2 did not yield any discernable defects, hmcn2/fbln1 double knockdown fish displayed blistering in the trunk, pointing to an essential contribution of these proteins from mesodermal sources for proper epidermal-dermal junction formation. In contrast, and unlike hmcn1 mutants, epidermal-dermal junctions in the fin folds of hmcn2/fbln1 double knockdown fish were only moderately affected. Instead, they displayed impaired migration of fin mesenchymal cells into the fin folds, pointing to a crucial role of Hmcn2 and Fbln1 to remodel the ECM of the fin fold interepidermal space, which is a prerequisite for fibroblast ingrowth. TEM analyses suggest that this ECM remodeling occurs at the level of actinotrichia, the collageneous migration substrate of mesenchymal cells, and at the level of cross fibers, which resemble mammalian microfibers. This work provides first insights into the role of Hmcn2 during vertebrate development, identifying it as an evolutionary conserved protein that acts in functional redundancy with Fbln1C and/or Fbln1D isoforms to regulate tissue adhesion and cell migration, while extending current knowledge of the functions of vertebrate Fbln1. PMID:22771579

Feitosa, Natalia Martins; Zhang, Jinli; Carney, Thomas J.; Metzger, Manuel; Korzh, Vladimir; Bloch, Wilhelm; Hammerschmidt, Matthias

2012-01-01

80

Doped semiconductor nanocrystal junctions  

SciTech Connect

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

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

2013-11-28

81

Development of the neuromuscular junction  

Microsoft Academic Search

The differentiation of the neuromuscular junction is a multistep process requiring coordinated interactions between nerve terminals and muscle. Although innervation is not needed for muscle production, the formation of nerve-muscle contacts, intramuscular nerve branching, and neuronal survival require reciprocal signals from nerve and muscle to regulate the formation of synapses. Following the production of muscle fibers, clusters of acetylcholine receptors

Veit Witzemann

2006-01-01

82

Sound Junction  

NSDL National Science Digital Library

It's hard to learn about music without listening to it closely, and this multimedia website created by a group of organizations in Britain (including the Royal Academy of Music), provides a surfeit of music from all genres. Through interactive games, musical excerpts, interviews, and other such devices, the SoundJunction site is a great way for anyone to learn about music. A good place to start is the "What can I do on SoundJunction?" overview feature, which walks users through the layout of the site. After that, visitors may wish to look at the left-hand side of the homepage and click on through such areas as "Explore Music", "How Music Works", "Music in Context", and "Composing and remixing". For budding Beethovens, there is the "Composer Tool", which allows users to create their own music. Music educators and those who are just generally curious will find that this site merits numerous return visits, and it may prove to be quite habit-forming, in the best possible sense of the phrase.

83

Science Junction  

NSDL National Science Digital Library

North Carolina State University has made available the Science Junction website. The goal of this website is to create an interaction between the researchers and educators at North Carolina State University and the teachers, children, and parents of North Carolina. In addition, the website aims to provide a center for teaching as well as learning and integrating science into people's daily lives. Sections provided at the website are: Data Depot, Student Station, and Teacher Terminal, among others. In the Game Room section, within the Student Station, users can "try their hand at hitting a space vehicle through a special track in space" in the game Space Track. This offers users a fun way to learn more about Newton's Laws while testing their skills and knowledge in physics. Although the website has been launched, some sections are still under construction.

84

p-n junction formation in InSb and InAs(1-x)Sb(x) by metalorganic chemical vapor deposition  

NASA Technical Reports Server (NTRS)

p-n junctions have been fabricated in InSb and InAs(1-x)Sb(x)(0.4 less than x less than 0.7) using metalorganic chemical vapor deposition. These junctions showed soft breakdown in addition to forward characteristics with a diode factor greater than 2. The ternary alloy has a cut-off wavelength in the 8-11-micron range, thus providing a potential material system for detectors covering the 8-12-micron range.

Chiang, P. K.; Bedair, S. M.

1985-01-01

85

Behavior of a chemically doped graphene junction  

NASA Astrophysics Data System (ADS)

Polyethylene imine and diazonium salts are used as complementary molecular dopants to engineer a doping profile in a graphene transistor. Electronic transport in this device reveals the presence of two distinct resistance maxima, alluding to neutrality point separation and subsequent formation of a spatially abrupt junction. Carrier mobility in this device is not significantly affected by molecular doping or junction formation, and carrier transmission is found to scale inversely with the effective channel length of the device. Chemical dilutions are used to modify the dopant concentration and, in effect, alter the properties of the junction.

Farmer, Damon B.; Lin, Yu-Ming; Afzali-Ardakani, Ali; Avouris, Phaedon

2009-05-01

86

Random telegraph signals in molecular junctions.  

PubMed

We investigate conductance fluctuations in molecular junctions using a mechanically controllable break junction setup in a liquid environment. In contrast to conventional break junction measurements, time-dependent conductance signals were recorded while reducing the gap size between the two contact electrodes. Only small amplitude fluctuations of the conductance are observed when measuring in pure solvent. Conductance traces recorded in solutions containing alkanedithiols show significantly larger fluctuations which can take the form of random telegraph signals. Such signals emerge in a limited conductance range, which corresponds well to the known molecular conductance of the compounds investigated. These large-amplitude fluctuations are attributed to the formation and thermally driven breaking of bonds between a molecule and a metal electrode and provide a still poorly explored source of information on the dynamics of molecular junctions formation. The lifetimes of the high and low conductance states are found to vary between 0.1 ms and 0.1 s. PMID:25352489

Brunner, Jan; González, Maria Teresa; Schönenberger, Christian; Calame, Michel

2014-11-26

87

Random telegraph signals in molecular junctions  

NASA Astrophysics Data System (ADS)

We investigate conductance fluctuations in molecular junctions using a mechanically controllable break junction setup in a liquid environment. In contrast to conventional break junction measurements, time-dependent conductance signals were recorded while reducing the gap size between the two contact electrodes. Only small amplitude fluctuations of the conductance are observed when measuring in pure solvent. Conductance traces recorded in solutions containing alkanedithiols show significantly larger fluctuations which can take the form of random telegraph signals. Such signals emerge in a limited conductance range, which corresponds well to the known molecular conductance of the compounds investigated. These large-amplitude fluctuations are attributed to the formation and thermally driven breaking of bonds between a molecule and a metal electrode and provide a still poorly explored source of information on the dynamics of molecular junctions formation. The lifetimes of the high and low conductance states are found to vary between 0.1 ms and 0.1 s.

Brunner, Jan; González, Maria Teresa; Schönenberger, Christian; Calame, Michel

2014-11-01

88

Genetic Diseases of Junctions  

Microsoft Academic Search

Tight junctions, gap junctions, adherens junctions, and desmosomes represent intricate structural intercellular channels and bridges that are present in several tissues, including epidermis. Clues to the important function of these units in epithelial cell biology have been gleaned from a variety of studies including naturally occurring and engineered mutations, animal models and other in vitro experiments. In this review, we

Joey E Lai-Cheong; Ken Arita; John A McGrath

2007-01-01

89

Solitons in Josephson junctions  

NASA Astrophysics Data System (ADS)

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.

Ustinov, A. V.

1998-11-01

90

Inhibition of gap junction and adherens junction assembly by connexin and A-CAM antibodies  

PubMed Central

We examined the roles of the extracellular domains of a gap junction protein and a cell adhesion molecule in gap junction and adherens junction formation by altering cell interactions with antibody Fab fragments. Using immunoblotting and immunocytochemistry we demonstrated that Novikoff cells contained the gap junction protein, connexin43 (Cx43), and the cell adhesion molecule, A-CAM (N-cadherin). Cells were dissociated in EDTA, allowed to recover, and reaggregated for 60 min in media containing Fab fragments prepared from a number of antibodies. We observed no cell-cell dye transfer 4 min after microinjection in 90% of the cell pairs treated with Fab fragments of antibodies for the first or second extracellular domain of Cx43, the second extracellular domain of connexin32 (Cx32) or A-CAM. Cell-cell dye transfer was detected within 30 s in cell pairs treated with control Fab fragments (pre- immune serum, antibodies to the rat major histocompatibility complex or the amino or carboxyl termii of Cx43). We observed no gap junctions by freeze-fracture EM and no adherens junctions by thin section EM between cells treated with the Fab fragments that blocked cell-cell dye transfer. Gap junctions were found on approximately 50% of the cells in control samples using freeze-fracture EM. We demonstrated with reaggregated Novikoff cells that: (a) functional interactions of the extracellular domains of the connexins were necessary for the formation of gap junction channels; (b) cell interactions mediated by A-CAM were required for gap junction assembly; and (c) Fab fragments of antibodies for A-CAM or connexin extracellular domains blocked adherens junction formation. PMID:1326565

1992-01-01

91

Junctions in the central nervous system of the cat  

Microsoft Academic Search

Interendothelial membrane contacts in different segments of brain blood vessels were investigated by the freeze-etching technique. The study demonstrated that the endothelial cells of the pre-and postcapillary segments were coupled by elaborate zonulae occludentes. These tight junction formations encompassed gap junctions of different sizes and distribution. The globules of the pre-and postcapillary tight junctions revealed a great fragility which led

Rolf Dermietzel

1975-01-01

92

Ultrastructural studies on neuromuscular contacts and the formation of junctions in the flight muscle of Antheraea polyphemus (Lep.). II. Changes after motor nerve section.  

PubMed

In the moth Antheraea polyphemed at the onset of adult development. The subsequent breakdown of the isolated motor stulongated vesicles similar in structure to channels of smooth ER, appear in large numbers in the axoplasm. Their nature as well as the functional aspects of early axonal changes are discussed. From the 7th day onward two types of axonal breakdown become prominent. The first is characterized 0y swelling axon profiles, distorted vesicles and strongly shrunken mitochondria, uhile shrinking axon profiles containing tightly packed mitochondria and unaltered vesicles are typical of the second. Both types presumably take place independently of each other in different axon terminals. Axons and the contents of at least the first type are finally removed by transformation into lamellar bodies. Glial processes obviously behave independently of degenerating terminals; they loose any contact with them and never act as phagocytes for axon remnants. During the whole period of breakdown undifferentiated contacts between nerve fibers and muscle anlagen are present but synaptic structures as in normal developing dlm have never been observed. This fact, in comparison with earlier studies, suggests a lack of trophic nervous activity on the muscle anlagen tissue. A short time after removal of the isolated stumps new nerve tracts appear between dlm-fibers (which are, of course, strongly retarded in development). They are presumably sensory wing nerves which lack a guide structure to the central target, due to axotomy. Neuromuscular contacts or even junctions formed by axons of these nerves have occasionally been detected on the dlm. Their nature is discussed. Wallerian axon degeneration is compared to the normal, metamorphic breakdown of the innervation of the larval dlm-precursor. In contrast to the former, glial processes here remain in contact with the terminals. Glia and axons first swell. Then most glial processes are transformed into lamellar bodies whereas neurites shrink and become electron-dense. Axonal organelles remain intact for a long period. PMID:1201608

Nüesch, H; Stocker, R F

1975-12-10

93

Thin Junction Trees  

Microsoft Academic Search

We present an algorithm that induces a class of models with thin junction trees—models that are characterized by an upper bound on the size of the maximal cliques of their triangulated graph. By ensurin g that the junction tree is thin, inference in our models remains tract able throughout the learning process. This allows both an efficient implemen tation of

Francis R. Bach; Michael I. Jordan

2001-01-01

94

The Bouvet Triple Junction.  

National Technical Information Service (NTIS)

The boundaries of three plates, South America, Africa, and Antarctica, Meet in a triple junction 250 km west of Bouvet Island. In the vicinity of the triple junction the most striking features of the Antarctica/South America and Africa/Antarctica plate bo...

J. G. Sclater, C. Bowin, R. Hey, H. Hoskins, J. Peirce

1975-01-01

95

Interface states and Schottky barrier formation at metal/GaAs junctions R. E. Viturro, c. Mailhiot, J. L. Shaw, and L. J. Brillson  

E-print Network

of values of the order ofthe semiconductor band gap. These studies ofroom- temperature formation of metal.4 GaP,' and InAs l showed a strong dependence of Schottky barrier heights (SEH's) on metal work of Schottky'S phenomenological description, thereby suggesting that metal- induced gap states and native

Woodall, Jerry M.

96

Metal Silicides: Active elements of ULSI contacts  

NASA Astrophysics Data System (ADS)

As device dimensions scale to the 0.1 urn regime, the self-aligned suicide (SALICIDE) contact technology increasingly becomes an integral part of both the ultra-shallow junction and the metal oxide semiconductor field-effect transistor device itself. This paper will discuss the effect of suicide materials and formation processes on suicide stability, junction consumption, the ability to accurately profile shallow junctions, and contact resistance in series with the channel. The use of suicides as diffusion sources (SADS) provides an important pathway toward optimization of suicide technology. Diffusion of boron and arsenic from nearly epitaxial layers of CoSi2, formed from bilayers of Ti and Co, offer good suicide stability, ultra-shallow, low-leakage junctions, and low contact resistance.

Osburn, C. M.; Tsai, J. Y.; Sun, J.

1996-11-01

97

On the formation and evolution of the Pannonian basin: constraints derived from the orogenic collapse recorded at the junction between Carpathians and Dinarides  

NASA Astrophysics Data System (ADS)

Formation and evolution of back-arc basins is related to the evolution of subduction zones, resulting geometries being dependent on the interplay between the velocity of retreating slabs and boundary conditions that often limit rapid subduction systems. Classical models of evolution in the Alps-Carpathians-Dinaridic domain assume that the formation of the Pannonian back-arc basin is related to the rapid roll-back of an European slab and the invasion of Tisza-Dacia and ALCAPA upper plate blocks into the so-called Carpathians embayment starting at ~20Ma. The general mechanism assumes a gradual evolution, an initial mechanical phase of extensional detachments being recognized near the transition between the Alps and the Pannonian basin was subsequently followed by upper crustal normal faulting and a thermal phase during the Middle-late Miocene times that affected the central part of the Pannonian basin. A key area of the entire system often neglected by kinematic studies is the connection between South Carpathians and Dinarides. Here, regional seismic lines traversing the entire Serbian part of the Pannonian basin were calibrated with well data in order to derive an evolutionary model. The deformation is dominantly expressed by the formation of extensional (half-)grabens that are the brittle expression of large-scale extensional detachments. In contrast with previous interpretation restricting the syn-rift phase to the Middle Miocene, the geometry of normal faults and the associated syn-kinematic sedimentation allows the definition of a continuous Early to Late Miocene extensional evolution that was followed by the formation of isolated uplifted areas during the subsequent Pliocene - Quaternary inversion. The orientation of these (half-)grabens changes gradually from W-E to NW-SE and then to N-S, suggesting that the present-day strike of faults is the effect of a clockwise rotational mechanism of South Carpathians and Apuseni Mountains in respect to Dinarides. The S-ward prolongation of the large scale extension in an area that is adjacent across Carpathians to the Moesian platform suggests that the roll-back of the Carpathians is not the only mechanism that is responsible for the formation of the Pannonian basin. The correlation with similar extensional structures superposed over the orogenic chain located S-wards strongly points towards a component of Pannonian collapse driven by a Middle Miocene roll-back of a Dinaridic slab. The study provides critical constraints for the pre-Neogene evolution of an area where there major crustal blocks (i.e. Tisza, Dacia and Dinarides) are juxtaposed together with their partly overlying obducted ophiolitic sequences against the major oceanic suture of Dinarides, the Sava zone.

Matenco, L. C.; Radivojevic, D.

2012-04-01

98

ZO-1 recruitment to ?-catenin - a novel mechanism for coupling the assembly of tight junctions to adherens junctions  

PubMed Central

Summary The formation of a barrier between epithelial cells is a fundamental determinant of cellular homeostasis, protecting underlying cells against pathogens, dehydration and damage. Assembly of the tight junction barrier is dependent upon neighboring epithelial cells binding to one another and forming adherens junctions, but the mechanism for how these processes are linked is poorly understood. Using a knockdown and substitution system, we studied whether ZO-1 binding to ?-catenin is required for coupling tight junction assembly to the formation of adherens junctions. We found that preventing ZO-1 binding to ?-catenin did not appear to affect adherens junctions. Rather the assembly and maintenance of the epithelial barrier were disrupted. This disruption was accompanied by alterations in the mobility of ZO-1 and the organization of the actin cytoskeleton. Thus, our study identifies ?-catenin binding to ZO-1 as a new mechanism for coupling the assembly of the epithelial barrier to cell-to-cell adhesion. PMID:23813953

Maiers, Jessica L.; Peng, Xiao; Fanning, Alan S.; DeMali, Kris A.

2013-01-01

99

Rectosigmoid Junction Coding Guidelines  

Cancer.gov

Coding Guidelines Rectosigmoid Junction C199 Primary Site A tumor is classified as rectosigmoid when differentiation between rectum and sigmoid is not possible. A tumor is classified as rectal if • lower margin lies less than 16 cm from the anal

100

Oxidative Stress, Lens Gap Junctions, and Cataracts  

PubMed Central

Abstract The eye lens is constantly subjected to oxidative stress from radiation and other sources. The lens has several mechanisms to protect its components from oxidative stress and to maintain its redox state, including enzymatic pathways and high concentrations of ascorbate and reduced glutathione. With aging, accumulation of oxidized lens components and decreased efficiency of repair mechanisms can contribute to the development of lens opacities or cataracts. Maintenance of transparency and homeostasis of the avascular lens depend on an extensive network of gap junctions. Communication through gap junction channels allows intercellular passage of molecules (up to 1?kDa) including antioxidants. Lens gap junctions and their constituent proteins, connexins (Cx43, Cx46, and Cx50), are also subject to the effects of oxidative stress. These observations suggest that oxidative stress-induced damage to connexins (and consequent altered intercellular communication) may contribute to cataract formation. Antioxid. Redox Signal. 11, 339–353. PMID:18831679

Beyer, Eric C.

2009-01-01

101

Early events in neuromuscular junction formation in vitro: induction of acetylcholine receptor clusters in the postsynaptic membrane and morphology of newly formed synapses  

PubMed Central

The development of clusters of acetylcholine (ACh) receptors at newly formed synapses between embryonic chick spinal cord and muscle cells grown in vitro has been studied by iontophoretic mapping with ACh. A semi-automated technique using on-line computer analysis of ACh responses and a photographic system to record the position of each ACh application permit the rapid construction of extensive and detailed maps of ACh sensitivity. Clusters of receptors, evident as peaks of ACh sensitivity, are present on many uninnervated myotubes. The distribution of ACh sensitivity closely parallels the distribution of 125I-alpha-bungarotoxin binding sites on the same muscle cell. In all cases where individual myotubes were adequately mapped before and after synapse formation, ingrowing axons induced new clusters of receptors rather than seeking out preexisting clusters. Synapses can form at active growth cones within 3 h of nerve-muscle contact. New receptor clusters can appear beneath neurites within a few hours. Many of the uninnervated clusters on innervated myotubes disappear with time. In contrast, receptor clusters on uninnervated myotubes remain in the same location for many hours. Synaptic clusters and clusters on uninervated myotubes are stable even though individual receptors are metabolized rapidly. The morphology of several identified sites of transmitter release was examined. At the scanning EM level, synapses appeared as small, rough-surfaced varicosities with filopodia that radiated outwards over the muscle surface. One synapse was studied by transmission EM. Acetylcholinesterase and a basement lamina were present within the synaptic cleft. PMID:511937

1979-01-01

102

Magnetic Tunnel Junctions  

NASA Astrophysics Data System (ADS)

In magnetoelectronic devices large opportunities are opened by the spin dependent tunneling resistance, where a strong dependence of the tunneling current on the relative orientation of the magnetization of the electrodes is found. Within a short time, the amplitude of the resistance change of the junctions increased dramatically. We will cover Al-O and MgO based junctions and present highly spin-polarized electrode materials such as Heusler alloys. Furthermore, we will give a short overview on applications such as read heads in hard disk drives, storage cells in MRAMs, field programmable logic circuits and biochips. Finally, we will discuss the currently growing field of current induced magnetization switching.

Reiss, Günter; Schmalhorst, Jan; Thomas, Andre; Hütten, Andreas; Yuasa, Shinji

103

Electronic Properties of Carbon Nanotubes and Junctions  

NASA Technical Reports Server (NTRS)

Metallic and semiconducting Single Wall Carbon Nanotubes (CNT) have recently been characterized using scanning tunneling microscopy (STM) and the manipulation of individual CNT has been demonstrated. These developments make the prospect of using CNT as molecular wires and possibly as electronic devices an even more interesting one. We have been modeling various electronic properties such as the density of states and the transmission coefficient of CNT wires and junctions. These studies involve first calculating the stability of junctions using molecular dynamics simulations and then calculating the electronic properties using a pi-electron tight binding Hamiltonian. We have developed the expertise to calculate the electronic properties of both finite-sized CNT and CNT systems with semi-infinite boundary conditions. In this poster, we will present an overview of some of our results. The electronic application of CNT that is most promising at this time is their use as molecular wires. The conductance can however be greatly reduced because of reflection due to defects and contacts. We have modeled the transmission through CNT in the presence of two types of defects: weak uniform disorder and strong isolated scatterers. We find that the conductance is affected in significantly different manners due to these defects Junctions of CNT have also been imaged using STM. This makes it essential to derive rules for the formation of junctions between tubes of different chirality, study their relative energies and electronic properties. We have generalized the rules for connecting two different CNT and have calculated the transmission and density of states through CNT junctions. Metallic and semiconducting CNT can be joined to form a stable junction and their current versus voltage characteristics are asymmetric. CNT are deformed by the application of external forces including interactions with a substrate or other CNT. In many experiments, these deformation are expected to occur naturally. We will present some preliminary results of our calculations of the modification of CNT electronic properties as a result of deformations.

Anantram, M. P.; Han, Jie; Yang, Liu; Govindan, T. R.; Jaffe, R.; Saini, Subhash (Technical Monitor)

1998-01-01

104

Molecular junctions by joining single-walled carbon nanotubes.  

PubMed

Crossing single-walled carbon nanotubes can be joined by electron beam welding to form molecular junctions. Stable junctions of various geometries are created in situ in a transmission electron microscope. Electron beam exposure at high temperatures induces structural defects which promote the joining of tubes via cross-linking of dangling bonds. The observations are supported by molecular dynamics simulations which show that the creation of vacancies and interstitials induces the formation of junctions involving seven- or eight-membered carbon rings at the surface between the tubes. PMID:12190529

Terrones, M; Banhart, F; Grobert, N; Charlier, J-C; Terrones, H; Ajayan, P M

2002-08-12

105

Wildlife Biologist Delta Junction, Alaska  

E-print Network

Wildlife Biologist Delta Junction, Alaska POSITION A Wildlife Biologist (Research Associate II). This position is located at Donnelly Training Area, Delta Junction, Alaska. ORGANIZATION CEMML is a research south of Delta Junction in Alaska and is located approximately 100 miles southeast of Fairbanks, Alaska

106

Victory Junction Gang Camp  

ERIC Educational Resources Information Center

This article describes the Victory Junction Gang Camp, a not-for-profit, NASCAR-themed camp for children with chronic medical conditions that serves 24 different disease groups. The mission of the camp is to give children life-changing camping experiences that are exciting, fun, and empowering in a safe and medically sound environment. While doing…

Shell, Ryan

2007-01-01

107

Measurement of Tunnel Junction Resistance during Formation  

E-print Network

, Julie S. Lee, Kenneth E. Laws, and Roger W. Bland Department of Physics and Astronomy, San Francisco section. Fig. 2. Gold contact pads. The cap layer is formed by sputtering with a 2­inch­diameter US' gun

Bland, Roger

108

Cell Adhesion Molecules at the Drosophila Neuromuscular Junction  

Microsoft Academic Search

\\u000a A major goal in neuroscience is the understanding of organizational principles underlying cellular communication and the ensuing\\u000a molecular integrations that lead to a functional nervous system. The establishment of neuromuscular connections (junctions)\\u000a is a complex process that requires enumerable cellular and molecular interactions. There are many known and well-characterized\\u000a molecular events involved in every aspect of neuromuscular junction (NMJ) formation.

Franklin A. Carrero-Martínez; Akira Chiba

109

THE BØIFOT ORTHOMODE JUNCTION  

Microsoft Academic Search

Wideband dual-polarization p erformance is desired for low-noi se rece ivers and radiometers at centimeter and m illimeter wavelengths. The use of a wavegui de orthomode transducer (OMT) can increase spectral coverage and sensitivity while reducing exit aperture size, optical spill, an d instr umental polarization offsets. For these reasons, an orthomode junction is favored over a t raditional quasi-optical

E. J. Wollack; W. Grammer; J. Kingsley

110

Involvement of nectin in the localization of junctional adhesion molecule at tight junctions.  

PubMed

Junctional adhesion molecule (JAM) is a Ca2+-independent immunoglobulin-like cell-cell adhesion molecule which localizes at tight junctions (TJs). Claudin is a key cell-cell adhesion molecule that forms TJ strands at TJs. JAM is associated with claudin through their cytoplasmic tail-binding protein, ZO-1. JAM is furthermore associated with Par-3, a cell polarity protein which forms a ternary complex with Par-6 and atypical protein kinase C. Nectin is another Ca2+-independent immunoglobulin-like cell-cell adhesion molecule which localizes at adherens junctions (AJs). Nectin is associated with E-cadherin through their respective cytoplasmic tail-binding proteins, afadin and catenins, and involved in the formation of AJs cooperatively with E-cadherin. We show here that nectin is furthermore involved in the localization of JAM at TJs. During the formation of the junctional complex consisting of AJs and TJs in Madin-Darby canine kidney (MDCK) cells, JAM was recruited to the nectin-based cell-cell adhesion sites. This recruitment of JAM was inhibited by nectin inhibitors, which inhibited the trans-interaction of nectin. Microbeads coated with the extracellular fragment of nectin, that interacted with cellular nectin, also recruited JAM to the bead-MDCK cell contact sites. Furthermore, when cadherin-deficient L fibroblasts stably expressing both exogenous JAM and nectin (nectin-JAM-L cells) were co-cultured with L fibroblasts expressing only nectin (nectin-L cells), JAM was concentrated at the cell-cell adhesion sites between nectin-JAM-L and nectin-L cells without the trans-interaction of JAM. Analyses of the localization and immunoprecipitation of JAM revealed that it was associated with nectin through afadin and ZO-1. These results suggest that nectin has a role in the localization of JAM at TJs in the process of the formation of the junctional complex in epithelial cells. PMID:12400007

Fukuhara, Atsunori; Irie, Kenji; Nakanishi, Hiroyuki; Takekuni, Kyoji; Kawakatsu, Tomomi; Ikeda, Wataru; Yamada, Akio; Katata, Tatsuo; Honda, Tomoyuki; Sato, Tatsuhiro; Shimizu, Kazuya; Ozaki, Harunobu; Horiuchi, Hisanori; Kita, Toru; Takai, Yoshimi

2002-10-31

111

Cementoenamel junction: An insight  

PubMed Central

The location and nature of cemento-enamel junction (CEJ) are more than descriptive terms used simply to describe some aspects of tooth morphology; however, CEJ gains a lot of clinical significance due to various measurements dependent on it. It may be necessary to determine the location and pathological changes occurring at CEJ to make a diagnosis and treat diseases pertaining to epithelial attachment and gingival margin. However, the information related to CEJ is not discussed commonly. Hence, the present review paper provides an insight on CEJ in both primary and permanent dentition.

Vandana, Kharidi Laxman; Haneet, Ryana Kour

2014-01-01

112

Golgi-associated cPLA2? Regulates Endothelial Cell-Cell Junction Integrity by Controlling the Trafficking of Transmembrane Junction Proteins  

PubMed Central

In endothelial cells specifically, cPLA2? translocates from the cytoplasm to the Golgi complex in response to cell confluence. Considering the link between confluence and cell–cell junction formation, and the emerging role of cPLA2? in intracellular trafficking, we tested whether Golgi-associated cPLA2? is involved in the trafficking of junction proteins. Here, we show that the redistribution of cPLA2? from the cytoplasm to the Golgi correlates with adherens junction maturation and occurs before tight junction formation. Disruption of adherens junctions using a blocking anti-VE-cadherin antibody reverses the association of cPLA2? with the Golgi. Silencing of cPLA2? and inhibition of cPLA2? enzymatic activity using various inhibitors result in the diminished presence of the transmembrane junction proteins VE-cadherin, occludin, and claudin-5 at cell–cell contacts, and in their accumulation at the Golgi. Altogether, our data support the idea that VE-cadherin triggers the relocation of cPLA2? to the Golgi and that in turn, Golgi-associated cPLA2? regulates the transport of transmembrane junction proteins through or from the Golgi, thereby controlling the integrity of endothelial cell–cell junctions. PMID:19675210

Krouwer, Vincent; Langelaar-Makkinje, Miriam; Nallan, Laxman; Gelb, Michael; Gerritsen, Hans; Verkleij, Arie J.; Post, Jan Andries

2009-01-01

113

Thermal Stability of Cu/NiSi-Contacted p+n Shallow Junction  

NASA Astrophysics Data System (ADS)

The thermal stability of Cu/NiSi-contacted p+n shallow junction diodes was investigated with respect to their electrical characteristics and metallurgical reactions. The TaN/Cu/NiSi/p+n junction diode remained intact after 30 min thermal annealing at temperatures of up to 350°C. Upon annealing at 375°C, a marked increase in reverse bias leakage current occurred, and secondary ion mass spectrometry (SIMS) analysis indicated that Cu started to penetrate into the NiSi-contacted shallow junction region. After a higher temperature annealing at 425°C, a Cu3Si phase was formed. The failure of the TaN/Cu/NiSi/p+n junction diodes is attributed to the penetration of Cu through the NiSi layer into the junction region, leading to junction degradation by introducing deep-level trap states and the eventual formation of Cu3Si.

Wang, Chao-Chun; Lin, Hsin-Hung; Chen, Mao-Chieh

2004-09-01

114

Resistive neuristor junctions  

NASA Technical Reports Server (NTRS)

A neuristor R-junction is provided by coupling neuristor lines by paths of varying resistance so that a pulse being propagated on one line when coupled to a portion of the second line through a relatively high resistive path will place the second line in the refractory mode thus preventing the propagation of a pulse through that portion of second line; however the same pulse coupled to another portion of the second line through a lower resistance path will cause a pulse to be produced in the second line and propagated in that portion of second line which is not in the refractory mode. Various logic and storage circuits are included in the disclosure.

Reible, Stanley A. (Inventor)

1976-01-01

115

Tight junction dynamics: the role of junctional adhesion molecules (JAMs).  

PubMed

Junctional adhesion molecules (JAMs) are a family of adhesion molecules localized at the tight junction of polarized cells and on the cell surface of leukocytes. The last 20 years of research in this field has shown that several members of the family play an important role in the regulation of cell polarity, endothelium permeability and leukocytes migration. They mediate these pleiotropic functions through a multitude of homophilic and heterophilic interactions with intrafamily and extrafamily partners. In this article, we review the current status of the JAM family and highlight their functional role in tight junction dynamics and leukocyte transmigration. PMID:24595739

Garrido-Urbani, S; Bradfield, P F; Imhof, B A

2014-03-01

116

Bile duct epithelial tight junctions and barrier function  

PubMed Central

Bile ducts play a crucial role in the formation and secretion of bile as well as excretion of circulating xenobiotic substances. In addition to its secretory and excretory functions, bile duct epithelium plays an important role in the formation of a barrier to the diffusion of toxic substances from bile into the hepatic interstitial tissue. Disruption of barrier function and toxic injury to liver cells appear to be involved in the pathogenesis of a variety of liver diseases such as primary sclerosing cholangitis, primary biliary cirrhosis and cholangiocarcinoma. Although the investigations into understanding the structure and regulation of tight junctions in gut, renal and endothelial tissues have expanded rapidly, very little is known about the structure and regulation of tight junctions in the bile duct epithelium. In this article we summarize the current understanding of physiology and pathophysiology of bile duct epithelium, the structure and regulation of tight junctions in canaliculi and bile duct epithelia and different mechanisms involved in the regulation of disruption and protection of bile duct epithelial tight junctions. This article will make a case for the need of future investigations toward our understanding of molecular organization and regulation of canalicular and bile duct epithelial tight junctions. PMID:24665411

Rao, R.K.; Samak, G.

2013-01-01

117

Dispersion relation for surface plasmon polaritons on a Schottky junction.  

PubMed

The conventional analysis of surface plasmon modes on dielectric-metal interfaces requires clearly defining the permittivity discontinuity at the interface. A pivotal assumption of such an analysis is that the formation of the dielectric-metal interface does not change the material properties and the materials forming the interface have identical permittivities before and after the formation of the interface. However, this assumption breaks down if an interface is made between a metal and a semiconductor which is commonly known as a Schottky junction. Under certain conditions, such an interface can sustain a surface plasmon polariton (SPP) mode. It is also possible to change the properties of the media surrounding the Schottky junction interface by applying an external potential difference across the junction. Central to the understanding of the SPP mode behaviour in such a complex morphological interface is the dispersion relation which defines the feasible SPP modes and their characteristics. Here, we carry out a detailed analysis to derive an analytical expression for the dispersion relation for a Schottky junction. Our analysis takes into account the space charge layer formed due to the charge distribution across the Schottky junction and resulting new boundary conditions. PMID:22453397

Wijesinghe, Thamani; Premaratne, Malin

2012-03-26

118

Probing Electronic and Thermoelectric Properties of Single Molecule Junctions  

NASA Astrophysics Data System (ADS)

In an effort to further understand electronic and thermoelectric phenomenon at the nanometer scale, we have studied the transport properties of single molecule junctions. To carry out these transport measurements, we use the scanning tunneling microscope-break junction (STM-BJ) technique, which involves the repeated formation and breakage of a metal point contact in an environment of the target molecule. Using this technique, we are able to create gaps that can trap the molecules, allowing us to sequentially and reproducibly create a large number of junctions. By applying a small bias across the junction, we can measure its conductance and learn about the transport mechanisms at the nanoscale. The experimental work presented here directly probes the transmission properties of single molecules through the systematic measurement of junction conductance (at low and high bias) and thermopower. We present measurements on a variety of molecular families and study how conductance depends on the character of the linkage (metal-molecule bond) and the nature of the molecular backbone. We start by describing a novel way to construct single molecule junctions by covalently connecting the molecular backbone to the electrodes. This eliminates the use of linking substituents, and as a result, the junction conductance increases substantially. Then, we compare transport across silicon chains (silanes) and saturated carbon chains (alkanes) while keeping the linkers the same and find a stark difference in their electronic transport properties. We extend our studies of molecular junctions by looking at two additional aspects of quantum transport -- molecular thermopower and molecular current-voltage characteristics. Each of these additional parameters gives us further insight into transport properties at the nanoscale. Evaluating the junction thermopower allows us to determine the nature of charge carriers in the system and we demonstrate this by contrasting the measurement of amine-terminated and pyridine-terminated molecules (which exhibit hole transport and electron transport, respectively). We also report the thermopower of the highly conducting, covalently bound molecular junctions that we have recently been able to form, and learn that, because of their unique transport properties, the junction power factors, GS2, are extremely high. Finally, we discuss the measurement of molecular current-voltage curves and consider the electronic and physical effects of applying a large bias to the system. We conclude with a summary of the work discussed and an outlook on related scientific studies.

Widawsky, Jonathan R.

119

Molecular Components of the Adherens Junction  

PubMed Central

Adherens junctions serve to couple individual cells into various arrangements required for tissue structure and function. The central structural components of adherens junctions are transmembrane adhesion receptors, and their associated actin-binding/regulatory proteins. The molecular machineries that organize these adhesion receptor complexes into higher order junction structures, and the functional consequences of this junctional organization will be discussed. PMID:18206110

Niessen, Carien M.; Gottardi, Cara J.

2008-01-01

120

Josephson junction Q-spoiler  

DOEpatents

An automatic Q-spoiler comprising at least one Josephson tunnel junction connected in an LC circuit for flow of resonant current therethrough. When in use in a system for detecting the magnetic resonance of a gyromagnetic particle system, a high energy pulse of high frequency energy irradiating the particle system will cause the critical current through the Josephson tunnel junctions to be exceeded, causing the tunnel junctions to act as resistors and thereby damp the ringing of the high-Q detection circuit after the pulse. When the current has damped to below the critical current, the Josephson tunnel junctions revert to their zero-resistance state, restoring the Q of the detection circuit and enabling the low energy magnetic resonance signals to be detected.

Clarke, J.; Hilbert, C.; Hahn, E.L.; Sleator, T.

1986-03-25

121

Solute and dislocation junction interactions  

SciTech Connect

In this study, the role of solute segregation on the strength and the evolution behavior of dislocation junctions is studied by utilizing kinetic Monte Carlo and three-dimensional dislocation dynamics simulations. The different solute concentrations and the character of the junctions are all included in the simulations in an effort to make a parametric investigation. The results indicate that the solutes have a profound effect on the strength of the junctions. Solute segregation can lead to both strengthening and weakening behavior, depending upon the evolution of the dislocation junctions. The local solute concentration seems to be the more relevant parameter to characterizing the solute and dislocation interactions, due to the short-range stress field of solutes; and its bounds are set by the unconstrained volume dilatation.

Chen, Q.; Liu, X.-Y.; Biner, S. B.

2008-03-19

122

Rap1 potentiates endothelial cell junctions by spatially controlling myosin II activity and actin organization  

PubMed Central

Reorganization of the actin cytoskeleton is responsible for dynamic regulation of endothelial cell (EC) barrier function. Circumferential actin bundles (CAB) promote formation of linear adherens junctions (AJs) and tightening of EC junctions, whereas formation of radial stress fibers (RSF) connected to punctate AJs occurs during junction remodeling. The small GTPase Rap1 induces CAB formation to potentiate EC junctions; however, the mechanism underlying Rap1-induced CAB formation remains unknown. Here, we show that myotonic dystrophy kinase–related CDC42-binding kinase (MRCK)-mediated activation of non-muscle myosin II (NM-II) at cell–cell contacts is essential for Rap1-induced CAB formation. Our data suggest that Rap1 induces FGD5-dependent Cdc42 activation at cell–cell junctions to locally activate the NM-II through MRCK, thereby inducing CAB formation. We further reveal that Rap1 suppresses the NM-II activity stimulated by the Rho–ROCK pathway, leading to dissolution of RSF. These findings imply that Rap1 potentiates EC junctions by spatially controlling NM-II activity through activation of the Cdc42–MRCK pathway and suppression of the Rho–ROCK pathway. PMID:24019534

Ando, Koji; Moriya, Takahiro; Obara, Yutaro; Nakahata, Norimichi

2013-01-01

123

Octagonal Defects at Carbon Nanotube Junctions  

PubMed Central

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

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

2013-01-01

124

Wnt Signaling in Neuromuscular Junction Development  

PubMed Central

Wnt proteins are best known for their profound roles in cell patterning, because they are required for the embryonic development of all animal species studied to date. Besides regulating cell fate, Wnt proteins are gaining increasing recognition for their roles in nervous system development and function. New studies indicate that multiple positive and negative Wnt signaling pathways take place simultaneously during the formation of vertebrate and invertebrate neuromuscular junctions. Although some Wnts are essential for the formation of NMJs, others appear to play a more modulatory role as part of multiple signaling pathways. Here we review the most recent findings regarding the function of Wnts at the NMJ from both vertebrate and invertebrate model systems. PMID:22510459

Koles, Kate

2012-01-01

125

Chlorpromazine reduces the intercellular communication via gap junctions in mammalian cells  

SciTech Connect

In the work presented herein, we evaluated the effect of chlorpromazine (CPZ) on gap junctions expressed by two mammalian cell types; Gn-11 cells (cell line derived from mouse LHRH neurons) and rat cortical astrocytes maintained in culture. We also attempted to elucidate possible mechanisms of action of CPZ effects on gap junctions. CPZ, in concentrations comparable with doses used to treat human diseases, was found to reduce the intercellular communication via gap junctions as evaluated with measurements of dye coupling (Lucifer yellow). In both cell types, maximal inhibition of functional gap junctions was reached within about 1 h of treatment with CPZ, an recovery was almost complete at about 5 h after CPZ wash out. In both cell types, CPZ treatment increased the phosphorylation state of connexin43 (Cx43), a gap junction protein subunit. Moreover, CPZ reduced the reactivity of Cx43 (immunofluorescence) at cell interfaces and concomitantly increased its reactivity in intracellular vesicles, suggesting an increased retrieval from and/or reduced insertion into the plasma membrane. CPZ also caused cellular retraction reducing cell-cell contacts in a reversible manner. The reduction in contact area might destabilize existing gap junctions and abrogate formation of new ones. Moreover, the CPZ-induced reduction in gap junctional communication may depend on the connexins (Cxs) forming the junctions. If Cx43 were the only connexin expressed, MAPK-dependent phosphorylation of this connexin would induce closure of gap junction channels.

Orellana, Juan A. [Departamento de Ciencias Fisiologicas, Pontificia Universidad Catolica de Chile, Alameda 340, Santiago (Chile); Palacios-Prado, Nicolas [Departamento de Ciencias Fisiologicas, Pontificia Universidad Catolica de Chile, Alameda 340, Santiago (Chile); Saez, Juan C. [Departamento de Ciencias Fisiologicas, Pontificia Universidad Catolica de Chile, Alameda 340, Santiago (Chile)]. E-mail: jsaez@bio.puc.cl

2006-06-15

126

Single Molecule Junctions: Probing Contact Chemistry and Fundamental Circuit Laws  

SciTech Connect

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].

Hybertsen M. S.

2013-04-11

127

Numerical Study of ?-JUNCTION Using Spin Filtering Barriers  

NASA Astrophysics Data System (ADS)

We numerically investigate the Josephson transport through ferromagnetic insulators (FIs) by taking into account its band structure. By use of the recursive Green's function method, we found the formation of the ? junction in the case of the fully spin-polarized FI (FPFI), e.g., La2BaCuO5. Moreover, the 0-? transition is induced by increasing the thickness of FPFI. On the other hand, Josephson current through the Eu chalcogenides shows the ? junction behavior in the case of the strong d-f hybridization between the conduction d and the localized f electrons of Eu. Such FI-based Josephson junctions may becomes a element in the architecture of future quantum information devices.

Kawabata, Shiro; Asano, Yasuhiro

128

Numerical Study of ?-JUNCTION Using Spin Filtering Barriers  

NASA Astrophysics Data System (ADS)

We numerically investigate the Josephson transport through ferromagnetic insulators (FIs) by taking into account its band structure. By use of the recursive Green's function method, we found the formation of the ? junction in the case of the fully spin-polarized FI (FPFI), e.g., La2BaCuO5. Moreover, the 0-? transition is induced by increasing the thickness of FPFI. On the other hand, Josephson current through the Eu chalcogenides shows the ? junction behavior in the case of the strong d-f hybridization between the conduction d and the localized f electrons of Eu. Such FI-based Josephson junctions may becomes a element in the architecture of future quantum information devices.

Kawabata, Shiro; Asano, Yasuhiro

2010-12-01

129

MgcRacGAP interacts with cingulin and paracingulin to regulate Rac1 activation and development of the tight junction barrier during epithelial junction assembly  

PubMed Central

The regulation of Rho-family GTPases is crucial to direct the formation of cell–cell junctions and tissue barriers. Cingulin (CGN) and paracingulin (CGNL1) control RhoA activation in epithelial cells by interacting with RhoA guanidine exchange factors. CGNL1 depletion also inhibits Rac1 activation during junction assembly. Here we show that, unexpectedly, Madin–Darby canine kidney epithelial cells depleted of both CGN and CGNL1 (double-KD cells) display normal Rac1 activation and tight junction (TJ) formation, despite decreased junctional recruitment of the Rac1 activator Tiam1. The expression of the Rac1 inhibitor MgcRacGAP is decreased in double-KD cells, and the barrier development and Rac1 activation phenotypes are rescued by exogenous expression of MgcRacGAP. MgcRacGAP colocalizes with CGN and CGNL1 at TJs and forms a complex and interacts directly in vitro with CGN and CGNL1. Depletion of either CGN or CGNL1 in epithelial cells results in decreased junctional localization of MgcRacGAP but not of ECT2, a centralspindlin-interacting Rho GEF. These results provide new insight into coordination of Rho-family GTPase activities at junctions, since apical accumulation of CGN and CGNL1 at TJs during junction maturation provides a mechanism to spatially restrict down-regulation of Rac1 activation through the recruitment of MgcRacGAP. PMID:24807907

Guillemot, Laurent; Guerrera, Diego; Spadaro, Domenica; Tapia, Rocio; Jond, Lionel; Citi, Sandra

2014-01-01

130

Abnormal junction leakage characteristics in titanium-capped cobalt disilicide  

NASA Astrophysics Data System (ADS)

Abnormal junction leakage characteristics in titanium-capped cobalt disilicide were investigated. The cobalt silicide n+-p junctions, fabricated with different capping layers, were characterized by current-voltage measurements and transmission electron microscopy. The reverse junction leakage currents of Ti-capped 13.5-nm-thick cobalt disilicide (CT) are higher than those of TiN-capped samples. The activation energy of CT at temperatures below 80 °C is 0.41 eV, and its dominant leakage mechanism is consistent with phonon-assisted tunneling. Transmission electron microscopy analysis indicates the existence of island phases and precipitates located at the silicide/Si interface, which are titanium disilicide and CoxTi1-xSi2 phases, as evidenced by energy dispersive spectroscopy. As a result, for the case of CT, the reasons for higher junction leakage currents and their field dependence appear to be the result of the diffusion of Ti atoms into CoSi2 grain boundaries and the resulting formation of TiSi2 and CoxTi1-xSi2 phases, which gives rise to a rougher silicide interface and a close spacing between silicide and the junction.

Kang, Chang-Yong; Kang, Dae-Gwan; Lee, Joo-Wan

1999-11-01

131

Investigation of Junction Properties of CdS/CdTe Solar Cells and their Correlation to Device Properties (Presentation)  

SciTech Connect

The objective of the Junction Studies are: (1) understand the nature of the junction in the CdTe/CdS device; (2) correlate the device fabrication parameters to the junction formation; and (3) develop a self consistent device model to explain the device properties. Detailed analysis of CdS/CdTe and SnO{sub 2}/CdTe devices prepared using CSS CdTe is discussed.

Dhere, R. G.; Zhang, Y.; Romero, M. J.; Asher, S. E.; Young, M.; To, B.; Noufi, R.; Gessert, T. A.

2008-05-01

132

Dislocation Dynamics Simulations of Junctions in Hexagonal Close-Packed Crystals  

SciTech Connect

The formation and strength of dislocations in the hexagonal closed packed material beryllium are studied through dislocation junctions and the critical stress required to break them. Dislocation dynamics calculations (using the code ParaDiS) of junction maps are compared to an analytical line tension approximation in order to validate our model. Results show that the two models agree very well. Also the critical shear stress necessary to break 30{sup o} - 30{sup o} and 30{sup o} - 90{sup o} dislocation junctions is computed numerically. Yield surfaces are mapped out for these junctions to describe their stability regions as function of resolved shear stresses on the glide planes. The example of two non-coplanar binary dislocation junctions with slip planes [2-1-10] (01-10) and [-12-10] (0001) corresponding to a prismatic and basal slip respectively is chosen to verify and validate our implementation.

Wu, C; Aubry, S; Chung, P; Arsenlis, A

2011-12-05

133

T7 endonuclease I resolves Holliday junctions formed in vitro by RecA protein.  

PubMed Central

T7 endonuclease I is known to bind and cleave four-way junctions in DNA. Since these junctions serve as analogues of Holliday junctions that arise during genetic recombination, we have investigated the action of T7 endonuclease I on recombination intermediates containing Holliday junctions. We find that addition of T7 endonuclease I to strand exchange reactions catalysed by RecA protein of Escherichia coli leads to the formation of duplex products that correspond to 'patch' and 'splice' type recombinants. Resolution of the recombination intermediates occurs by the introduction of nicks at the site of the Holliday junction. The recombinant molecules contain 5'-phosphate and 3'-hydroxyl termini which may be ligated to restore the integrity of the DNA. Images PMID:2216756

Muller, B; Jones, C; West, S C

1990-01-01

134

The kidney tight junction (Review)  

PubMed Central

The tight junction is an important subcellular organelle which plays a vital role in epithelial barrier function. Claudin, as the integral membrane component of tight junctions, creates a paracellular transport pathway for various ions to be reabsorbed by the kidneys. This review summarizes advances in claudin structure, function and pathophysiology in kidney diseases. Different claudin species confer selective paracellular permeability to each of three major renal tubular segments: the proximal tubule, the thick ascending limb of Henle’s loop and the distal nephron. Defects in claudin function can cause a wide spectrum of kidney diseases, such as hypomagnesemia, hypercalciuria, kidney stones and hypertension. Studies using transgenic mouse models with claudin mutations have recapitulated several of these renal disease phenotypes and have elucidated the underlying biological mechanisms. Modern recording approaches based upon scanning ion conductance microscopy may resolve the biophysical nature of claudin transport function and provide novel insight into tight junction architecture. PMID:25319473

HOU, JIANGHUI

2014-01-01

135

The kidney tight junction (Review).  

PubMed

The tight junction is an important subcellular organelle which plays a vital role in epithelial barrier function. Claudin, as the integral membrane component of tight junctions, creates a paracellular transport pathway for various ions to be reabsorbed by the kidneys. This review summarizes advances in claudin structure, function and pathophysiology in kidney diseases. Different claudin species confer selective paracellular permeability to each of three major renal tubular segments: the proximal tubule, the thick ascending limb of Henle's loop and the distal nephron. Defects in claudin function can cause a wide spectrum of kidney diseases, such as hypomagnesemia, hypercalciuria, kidney stones and hypertension. Studies using transgenic mouse models with claudin mutations have recapitulated several of these renal disease phenotypes and have elucidated the underlying biological mechanisms. Modern recording approaches based upon scanning ion conductance microscopy may resolve the biophysical nature of claudin transport function and provide novel insight into tight junction architecture. PMID:25319473

Hou, Jianghui

2014-12-01

136

Probing ?-coupling in molecular junctions  

PubMed Central

Charge transport characteristics for metal–molecule–metal junctions containing two structurally related ?-conjugated systems were studied to probe ?–? interactions in molecular junctions. The first molecule contains a typical ?-conjugated framework derived from phenylene vinylene units, whereas the second has the phenylene vinylene structure interrupted by a [2.2]paracyclophane (pCp) core. Electrochemical investigations were used to characterize the defects and packing density of self-assembled monolayers of the two molecules on gold surfaces and to enable quantitative comparison of their transport characteristics. Current–voltage measurements across molecular junctions containing the two species demonstrate that the pCp moiety yields a highly conductive break in through-bond ?-conjugation. The observed high conductivity is consistent with density functional theory calculations, which demonstrate strong through-space ?–? coupling across the pCp moiety. PMID:15956193

Seferos, Dwight S.; Trammell, Scott A.; Bazan, Guillermo C.; Kushmerick, James G.

2005-01-01

137

Shear-induced reorganization of renal proximal tubule cell actin cytoskeleton and apical junctional complexes  

PubMed Central

In this study, we demonstrate that fluid shear stress (FSS)-induced actin cytoskeletal reorganization and junctional formation in renal epithelial cells are nearly completely opposite the corresponding changes in vascular endothelial cells (ECs) [Thi MM et al. (2004) Proc Natl Acad Sci USA 101:16483–16488]. Mouse proximal tubule cells (PTCs) were subjected to 5 h of FSS (1 dyn/cm2) to investigate the dynamic responses of the cytoskeletal distribution of filamentous actin (F-actin), ZO-1, E-cadherin, vinculin, and paxillin to FSS. Immunofluorescence analysis revealed that FSS caused basal stress fiber disruption, more densely distributed peripheral actin bands (DPABs), and the formation of both tight junctions (TJs) and adherens junctions (AJs). A dramatic reinforcement of vinculin staining was found at the cell borders as well as the cell interior. These responses were abrogated by the actin-disrupting drug, cytochalasin D. To interpret these results, we propose a “junctional buttressing” model for PTCs in which FSS enables the DPABs, TJs, and AJs to become more tightly connected. In contrast, in the “bumper-car” model for ECs, all junctional connections were severely disrupted by FSS. This “junctional buttressing” model explains why a FSS of only 1/10 of that used in the EC study can cause a similarly dramatic, cytoskeletal response in these tall, cuboidal epithelial cells; and why junctional buttressing between adjacent cells may benefit renal epithelium in maximizing flow-activated, brush border-dependent, transcellular salt and water reabsorption. PMID:18685100

Duan, Yi; Gotoh, Nanami; Yan, Qingshang; Du, Zhaopeng; Weinstein, Alan M.; Wang, Tong; Weinbaum, Sheldon

2008-01-01

138

Assessing individual radial junction solar cells over millions on VLS-grown silicon nanowires  

NASA Astrophysics Data System (ADS)

Silicon nanowires (SiNWs) grown on low-cost substrates provide an ideal framework for the monolithic fabrication of radial junction photovoltaics. However, the quality of junction formation over a random matrix of SiNWs, fabricated via a vapor-liquid-solid (VLS) mechanism, has never been assessed in a realistic context. To address this, we probe the current response of individual radial junction solar cells under electron-beam and optical-beam excitations. Excellent current generation from the radial junction units, compared to their planar counterparts, has been recorded, indicating a high junction quality and effective doping in the ultra-thin SiNWs with diameters thinner than 20 nm. Interestingly, we found that the formation of radial junctions by plasma deposition can be quite robust against geometrical disorder and even the crossings of neighboring cell units. These results provide a strong support to the feasibility of building high-quality radial junction solar cells over high-throughput VLS-grown SiNWs on low-cost substrates.

Yu, Linwei; Rigutti, Lorenzo; Tchernycheva, Maria; Misra, Soumyadeep; Foldyna, Martin; Picardi, Gennaro; Cabarrocas, Pere Roca i.

2013-07-01

139

Characterization of buried metal-molecule-metal junctions using Fourier transform infrared microspectroscopy  

NASA Astrophysics Data System (ADS)

We have devised an infrared spectromicroscopy based experimental configuration to enable structural characterization of buried molecular junctions. Our design utilizes a small mercury drop at the focal point of an infrared microscope to act as a mirror in studying metal-molecule-metal (MmM) junctions. An organic molecular monolayer is formed either directly on the mercury drop or on a thin, infrared (IR) semi-transparent layer of Au deposited onto an IR transparent, undoped silicon substrate. Following the formation of the monolayer, films on either metal can be examined independently using specular reflection spectroscopy. Furthermore, by bringing together the two monolayers, a buried molecular bilayer within the MmM junction can be characterized. Independent examination of each half of the junction prior to junction formation also allows probing any structural and/or conformational changes that occur as a result of forming the bilayer. Because our approach allows assembling and disassembling microscopic junctions by forming and withdrawing Hg drops onto the monolayer covered metal, spatial mapping of junctions can be performed simply by translating the location of the derivatized silicon wafer. Finally, the applicability of this technique for the longer-term studies of changes in molecular structure in the presence of electrical bias is discussed.

Babayco, Christopher B.; Land, Donald P.; Parikh, Atul N.; Kiehl, Richard A.

2014-09-01

140

The development of the myotendinous junction. A review  

PubMed Central

Summary The myotendinous junction (MTJ) is a complex specialized region located at the muscle-tendon interface that represents the primary site of force transmission. Despite their different embryologic origins, muscle and tendon morphogenesis occurs in close spatial and temporal association. After muscle attachment, muscle and tendon constitute a dynamic and functional integrated unit that transduces muscle contraction force to the skeletal system. We review here the current understanding of MTJ formation describing changes during morphogenesis and focusing on the crosstalk between muscle and tendon cells that leads to the development of a functional MTJ. Molecules involved in the formation of the linkage, both at the tendon side and at the muscle side of the junction are described. Much of this knowledge comes from studies using different animal models such as mice, zebrafish and Drosophila where powerful methods for in vivo imaging and genetic manipulations can be used to enlighten this developmental process. PMID:23738275

Charvet, Benjamin; Ruggiero, Florence; Le Guellec, Dominique

2012-01-01

141

Spontaneous organization of the cortical structure through endogenous neural firing and gap junction transmission.  

PubMed

We explore the effects of gap junctions, direct neural transmission between adjacent cells, on activity-dependent network formation. It is found that endogenous neural activities and weak firing correlations via gap junctions can regulate elaborately both the topographic structure in vertical connections and the radial structure in horizontal connections. Provided that pre-establishment of the lateral connection structure is required for the postnatal cortical map organization and genetic factors cannot perform such detailed regulation of synaptic connections, neural interactions via gap junctions could play an indispensable role in the brain development. PMID:22484826

Cho, Myoung Won; Choi, M Y

2012-07-01

142

27 CFR 9.164 - River Junction.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false River Junction. 9.164 Section 9.164...American Viticultural Areas § 9.164 River Junction. (a) Name. The name of...viticultural area described in this section is “River Junction.” (b) Approved...

2010-04-01

143

27 CFR 9.164 - River Junction.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false River Junction. 9.164 Section 9.164...American Viticultural Areas § 9.164 River Junction. (a) Name. The name of...viticultural area described in this section is “River Junction.” (b) Approved...

2012-04-01

144

27 CFR 9.164 - River Junction.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false River Junction. 9.164 Section 9.164...American Viticultural Areas § 9.164 River Junction. (a) Name. The name of...viticultural area described in this section is “River Junction.” (b) Approved...

2013-04-01

145

27 CFR 9.164 - River Junction.  

...2014-04-01 2014-04-01 false River Junction. 9.164 Section 9.164...American Viticultural Areas § 9.164 River Junction. (a) Name. The name of...viticultural area described in this section is “River Junction.” (b) Approved...

2014-04-01

146

27 CFR 9.164 - River Junction.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false River Junction. 9.164 Section 9.164...American Viticultural Areas § 9.164 River Junction. (a) Name. The name of...viticultural area described in this section is “River Junction.” (b) Approved...

2011-04-01

147

An oven for many thermocouple reference junctions  

NASA Technical Reports Server (NTRS)

Compact, lightweight oven designed with geometric and heating symmetry holds many junctions at stable temperature. Oven has cylindrical wall with all points equidistant from heating coil. Thermocouple junctions are inserted in holes bored radially in wall. Sensor controls power supplied to heating coil, maintaining cylinder wall and junctions at constant temperature.

Leblanc, L. P.

1981-01-01

148

Molecular Junction Transport - Some Vibronic Effects  

Microsoft Academic Search

The behavior of molecular transport junctions in the coherent tunneling (Landauer-Imry) regime is rapidly becoming understood. But vibronic effects characterize molecules, and understanding how they act in such junctions is a significant issue. This talk will deal with the role of both weak and strong vibronic interactions in molecular junctions. The weak mixing appears in IETS spectra, and can be

Mark Ratner

2007-01-01

149

The Yolla Bolly junction revisited  

SciTech Connect

West of Red Bluff, California, rocks of the northern Coast Ranges, Klamath-Sierra Nevada, and Great Valley provinces come together at what has been called the Yolla Bolly junction. Mapping of the Red Bluff and Willows 1:100,000 quadrangles has greatly clarified the enigmatic features of this complex area. Terranes of the Klamath Mountains and their Cretaceous sedimentary cover have been thrust northwestward over the Elder Creek terrane and Franciscan rocks, north of the left-lateral Cold Fork fault zone. The Condrey Mountain window (Franciscan Pickett Peak terrane) provides a measure of the magnitude of this thrusting (ca 90 km). South of the Cold Fork fault zone, the Franciscan and Elder Creek terranes were driven southeastward as tectonic wedges onto Sierran-Klamath basement. Timing of this scissor-tectonics is not constrained near the junction, but further north in southwest Oregon, Lower Eocene strata were deformed by overthrusting of the Klamath block whereas Upper Eocene strata overlap the thrust, indicating that thrusting occurred between about 52 and 60 Ma. Plate reconstructions for this time interval indicate the close proximity of the Kula-Farallon-North America triple junction and that old (ca 100 m.y.) Farallon lithosphere was being subducted north of the junction whereas to the south, very young (ca 10 m.y.) Kula plate was presumably obducted onto North America.

Blake, M.C.; Jayko, A.S. (Geological Survey, Menlo Park, CA (United States)); Jones, D.L. (Univ. of California, Berkeley, CA (United States). Dept. of Geology and Geophysics); Engebretson, D.C. (Western Washington Univ., Bellingham, WA (United States). Dept. of Geology)

1993-04-01

150

Gap junctions and chagas disease.  

PubMed

Gap junction channels provide intercellular communication between cells. In the heart, these channels coordinate impulse propagation along the conduction system and through the contractile musculature, thereby providing synchronous and optimal cardiac output. As in other arrhythmogenic cardiac diseases, chagasic cardiomyopathy is associated with decreased expression of the gap junction protein connexin43 (Cx43) and its gene. Our studies of cardiac myocytes infected with Trypanosoma cruzi have revealed that synchronous contraction is greatly impaired and gap junction immunoreactivity is lost in infected cells. Such changes are not seen for molecules forming tight junctions, another component of the intercalated disc in cardiac myocytes. Transcriptomic studies of hearts from mouse models of Chagas disease and from acutely infected cardiac myocytes in vitro indicate profound remodelling of gene expression patterns involving heart rhythm determinant genes, suggesting underlying mechanisms of the functional pathology. One curious feature of the altered expression of Cx43 and its gene expression is that it is limited in both extent and location, suggesting that the more global deterioration in cardiac function may result in part from spread of damage signals from more seriously compromised cells to healthier ones. PMID:21884887

Adesse, Daniel; Goldenberg, Regina Coeli; Fortes, Fabio S; Jasmin; Iacobas, Dumitru A; Iacobas, Sanda; Campos de Carvalho, Antonio Carlos; de Narareth Meirelles, Maria; Huang, Huan; Soares, Milena B; Tanowitz, Herbert B; Garzoni, Luciana Ribeiro; Spray, David C

2011-01-01

151

Multifunctional strands in tight junctions  

Microsoft Academic Search

Tight junctions are one mode of cell–cell adhesion in epithelial and endothelial cellular sheets. They act as a primary barrier to the diffusion of solutes through the intercellular space, create a boundary between the apical and the basolateral plasma membrane domains, and recruit various cytoskeletal as well as signalling molecules at their cytoplasmic surface. New insights into the molecular architecture

Shoichiro Tsukita; Mikio Furuse; Masahiko Itoh

2001-01-01

152

The Junction Diode Basic Operation  

E-print Network

releases electrons into the semiconductor lattice. These electrons are not bound and are free to move about energy causes the electrons and holes to move randomly. Electrons diffuse across the junction into the p. A hole is the absence of an electron which acts as a positive charge. The p-type semiconductor is also

Leach Jr.,W. Marshall

153

Magnetic tunnel junction pattern technique  

Microsoft Academic Search

We have developed a magnetic tunnel junction (MTJ) pattern technique that involves transforming the magnetic layer above the tunnel barrier in unwanted areas into an insulator, thus providing insulation between different MTJ devices without suffering common tunnel barrier shorting problems. With this technique, 90%-100% yielding MTJ devices have been observed. MTJ results using this process are superior to an etching

Eugene Chen; Benjamin Schwarz; Chang Ju Choi; Witold Kula; Jerome Wolfman; Kamel Ounadjela; Sam Geha

2003-01-01

154

Calculation of liquid junction potentials  

SciTech Connect

Equations are given and procedures described for calculating liquid junction potentials over wide ranges of concentration and composition. Use is made of the Henderson continuous mixtures assumption, avoiding treatment of the codiffusion problem. Ionic mobilities and activities are incorporated realistically, making use of standard data on binary electrolyte solutions. For ionic strengths up to about 0.1, an equation is derived in terms of ionic properties specified for the two end solutions; typical accuracy is 0.1 mV for simple junctions between two concentrations of the same electrolyte, and 1-2 mV for more complex junctions. Higher concentrations require specification of ionic properties at points intermediate between the end solutions; approximations are developed which prove accurate to about 0.5 mV in simple cases at ionic strengths as high as 5, while in complex cases an accuracy of 1 to a few mV is found at ionic strengths as high as 4.5. Ionic strength ratios across the junctions examined range from 1:1 to 94:1, typically being about 20:1. A rule is given for determining mobilities and activities of ions in mixtures, using standard data for binary solutions. An expression is obtained for the activity coefficients of single ion constitutents in terms of mean activity coefficients, and an estimate of the associated error is derived. This is the error in dividing total cell potentials into a component due to electrode potentials and a component arising at the liquid junction; it appears to be of comparable magnitude to the errors, stated above, due to other approximations in the calculations described.

Harper, H.W.

1985-04-25

155

Tight Junction Proteins: From Barrier to Tumorigenesis  

PubMed Central

The tight junction is a multi-protein complex and is the apical most junctional complex in certain epithelial and endothelial cells. A great deal of attention has been devoted to the understanding of these proteins in contributing to the barrier function - that is, regulating the paracellular flux or permeability between adjacent cells. However, tight junction proteins are now recognized as having functions beyond the barrier. The focus of this review is to discuss the barrier function of the tight junction and to summarize the literature with a focus on the role of tight junction proteins in proliferation, transformation, and metastasis. PMID:23743355

Runkle, E. Aaron; Mu, David

2013-01-01

156

TEM4 is a junctional Rho GEF required for cell-cell adhesion, monolayer integrity and barrier function  

PubMed Central

Summary Signaling events mediated by Rho family GTPases orchestrate cytoskeletal dynamics and cell junction formation. The activation of Rho GTPases is tightly regulated by guanine-nucleotide-exchange factors (GEFs). In this study, we identified a novel Rho-specific GEF called TEM4 (tumor endothelial marker 4) that associates with multiple members of the cadherin–catenin complex and with several cytoskeleton-associated proteins. Depending on confluence, TEM4 localized to either actin stress fibers or areas of cell–cell contact. The junctional localization of TEM4 was independent of actin binding. Depletion of endogenous TEM4 by shRNAs impaired Madin–Darby canine kidney (MDCK) and human umbilical vein endothelial cell (HUVEC) cell junctions, disrupted MDCK acini formation in 3D culture and negatively affected endothelial barrier function. Taken together, our findings implicate TEM4 as a novel and crucial junctional Rho GEF that regulates cell junction integrity and epithelial and endothelial cell function. PMID:23729734

Ngok, Siu P.; Geyer, Rory; Kourtidis, Antonis; Mitin, Natalia; Feathers, Ryan; Der, Channing; Anastasiadis, Panos Z.

2013-01-01

157

Autonomic neuromuscular junctions: current developments and future directions.  

PubMed Central

(1) The autonomic neuromuscular junction has been defined, with emphasis on the role of muscle effector bundles and en passage release of transmitter from extensive terminal nerve varicosities to diffuse to muscle across variable and often wide junctional clefts. (2) A multiplicity of neurotransmitters is described in the autonomic nervous system, including purines, peptides, amino acids and monoamines. The ultrastructural identification, projections, roles and interactions of the different nerve types have been discussed. (3) It has been suggested that the part played by peripheral neuroeffector control mechanisms has been underestimated and includes cotransmission, pre- and post-junctional neuromodulation, and the participation of locally released agents. (4) A time-lapse film was shown of the formation of autonomic neuromuscular junctions in culture, introducing questions relating to long-term 'trophic' influences in the autonomic nervous system. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 18 PMID:3319994

Burnstock, G

1986-01-01

158

Rab13 Small G Protein and Junctional Rab13-binding Protein (JRAB) Orchestrate Actin Cytoskeletal Organization during Epithelial Junctional Development*  

PubMed Central

During epithelial junctional development, both vesicle transport and reorganization of the actin cytoskeleton must be spatiotemporally regulated. Coordination of these cellular functions is especially important, but the precise mechanism remains elusive. Previously, we identified junctional Rab13-binding protein (JRAB)/molecules interacting with CasL-like 2 (MICAL-L2) as an effector of the Rab13 small G protein, and we found that the Rab13-JRAB system may be involved in the formation of cell-cell adhesions via transport of adhesion molecules. Here, we showed that JRAB interacts with two actin-binding proteins, actinin-1 and -4, and filamentous actin via different domains and regulates actin cross-linking and stabilization through these interactions. During epithelial junctional development, JRAB is prominently enriched in the actin bundle at the free border; subsequently, JRAB undergoes a Rab13-dependent conformational change that is required for maturation of cell-cell adhesion sites. These results suggest that Rab13 and JRAB regulate reorganization of the actin cytoskeleton throughout epithelial junctional development from establishment to maturation of cell-cell adhesion. PMID:23100251

Sakane, Ayuko; Abdallah, Ahmed Alamir Mahmoud; Nakano, Kiyoshi; Honda, Kazufumi; Ikeda, Wataru; Nishikawa, Yumiko; Matsumoto, Mitsuru; Matsushita, Natsuki; Kitamura, Toshio; Sasaki, Takuya

2012-01-01

159

Spin filter superconducting tunnel junctions  

NASA Astrophysics Data System (ADS)

Studies of the spin filter properties of tunnel barriers consisting of the insulating ferromagnets, EuO and EuS have been conducted for many years, but detailed investigation and application of their properties has been restricted by difficulties associated with growth and stoichiometry. We have recently demonstrated a new insulating ferromagnetic material GdN and shown that GdN barriers are strongly spin-filtering and can be incorporated into superconducting tunnel junctions. S/Insulator/S tunnel junctions enable detailed investigation of the magnitude of non-tunnel (leakage) currents and the optimisation of the tunnel barrier. We show that our insulating ferromagnet devices have a very low zero-bias leakage, but that behaviour for higher bias voltages is strongly non-ideal. We will discuss the potential for such devices to be used as spin-sources for both conventional and superconducting spintronics.

Blamire, M. G.; Pal, A.; Barber, Z. H.; Senapati, Kartik

2012-10-01

160

Morphogenesis of rat myotendinous junction  

PubMed Central

Summary Myotendinous junction (MTJ) is the highly specialized complex which connects the skeletal muscle to the tendon for transmitting the contractile force between the two tissues. The purpose of this study was to investigate the MTJ development and rat EDL was chosen as a model. 1, 15, 30 day animals were considered and the junctions were analyzed by light and electron microscopy. The MTJ interface architecture increased during the development, extending the interaction between muscle and tendon. 1-day-old rats showed disorganized myofibril bundles, spread cytosol and incomplete rough endoplasmic reticulum, features partially improved in 15-day-old rats, and completely developed in 30-day-old animals. These findings indicate that muscle-tendon interface displays, during rat lifetime, numerically increased and longer tendon interdigitations, correlated with an improved organization of both tissues and with a progressive acquirement of full functionality. PMID:24596690

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

2013-01-01

161

JUNCTIONAL COMPLEXES IN VARIOUS EPITHELIA  

Microsoft Academic Search

ABSTRACT The epithelia of a number,of glands and,cavitary organs of the rat and,guinea,pig have been surveyed, and in all cases investigated, a characteristic tripartite junctional complex has been found,between,adjacent,cells. Although,the complex,differs in precise arrange- ment from one organ to another, it has been regularly encountered in the mucosal epi- thelia of the stomach, intestine, gall bladder, uterus, and oviduct; in

Marilyn G. Farquhar; George E. Palade

1963-01-01

162

The catenin/cadherin adhesion system is localized in synaptic junctions bordering transmitter release zones  

PubMed Central

Molecular mechanisms linking pre- and postsynaptic membranes at the interneuronal synapses are little known. We tested the cadherin adhesion system for its localization in synapses of mouse and chick brains. We found that two classes of cadherin-associated proteins, alpha N- and beta-catenin, are broadly distributed in adult brains, colocalizing with a synaptic marker, synaptophysin. At the ultrastructural level, these proteins were localized in synaptic junctions of various types, forming a symmetrical adhesion structure. These structures sharply bordered the transmitter release sites associated with synaptic vesicles, although their segregation was less clear in certain types of synapses. N-cadherin was also localized at a similar site of synaptic junctions but in restricted brain nuclei. In developing synapses, the catenin-bearing contacts dominated their junctional structures. These findings demonstrate that interneuronal synaptic junctions comprise two subdomains, transmitter release zone and catenin-based adherens junction. The catenins localized in these junctions are likely associated with certain cadherin molecules including N-cadherin, and the cadherin/ catenin complex may play a critical role in the formation or maintenance of synaptic junctions. PMID:8909549

1996-01-01

163

The Adherens Junction: A Mosaic of Cadherin and Nectin Clusters Bundled by Actin Filaments  

PubMed Central

Summary Cadherin and nectin are distinct transmembrane proteins of adherens junctions. Their ectodomains mediate adhesion while their cytosolic regions couple the adhesive contact to the cytoskeleton. Both these proteins are essential for adherens junction formation and maintenance. However, some basic aspects of these proteins, such as their organization in adherence junctions, have remained open. Therefore, using super-resolution microscopy and live-imaging, we focused on the subjunctional distribution of these proteins. We showed that cadherin and nectin in the junctions of A431 cells and human keratinocytes are located in separate clusters. The size of each cluster is independent of that of the adjacent clusters and can significantly fluctuate over time. Several nectin and cadherin clusters that constitute an individual adherens junction are united by the same actin filament bundle. Surprisingly, interactions between each cluster and F-actin are not uniform since neither vinculin nor LIM domain actin-binding proteins match the boundaries of cadherin or nectin clusters. Thus, the adherens junction is not a uniform structure but a mosaic of different adhesive units with very diverse modes of interaction with the cytoskeleton. We propose that such a mosaic architecture of adherence junctions is important for the fast regulation of their dynamics. PMID:23639974

Indra, Indrajyoti; Hong, Soonjin; Troyanovsky, Regina; Kormos, Bernadett; Troyanovsky, Sergey

2013-01-01

164

Investigation of modified p-n junctions in crystalline silicon on glass solar cells  

NASA Astrophysics Data System (ADS)

In this paper various methods for studying p-n junctions in thin film solar cells are applied with the aim to localize and investigate defects on a microscopic scale. Different electron and ion beam characterization methods are introduced to determine the p-n junction position using two different examples from crystalline silicon on glass thin film technology. In a first example, planview and cross section electron beam induced current measurements revealed that oxygen rich columnar growth at textured substrates strongly disturbs the p-n junction. In a second example, diffusion from glass substrate is identified by ToF-SIMS to influence the electrical and structural characteristics of the thin Si layer resulting in a modified p-n junction. A model describing the formation of both defect structures is introduced.

Lausch, D.; Werner, M.; Naumann, V.; Schneider, J.; Hagendorf, C.

2011-04-01

165

Gap junctions in health and disease  

Microsoft Academic Search

An international symposium was held on gap junctions in health and disease in Regensburg, Germany, gathering together a panel\\u000a of international scientists who discussed normal functions of gap junctions and their contribution to a variety of human diseases.\\u000a The emphasis was on strategies and models for a better understanding of gap junction-mediated cell-to-cell communication in\\u000a a variety of tissues, including

R. Dermietzel; F. Hofstädter

1998-01-01

166

String junction as a baryonic constituent  

NASA Astrophysics Data System (ADS)

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.

Kalashnikova, Yu. S.; Nefediev, A. V.

1996-02-01

167

Memory cell based on a ? Josephson junction  

NASA Astrophysics Data System (ADS)

The ? Josephson junction has a doubly degenerate ground state with the Josephson phases ±?. We demonstrate the use of such a ? Josephson junction as a memory cell (classical bit), where writing is done by applying a magnetic field and reading by applying a bias current. In the "store" state, the junction does not require any bias or magnetic field, but just needs to stay cooled for permanent storage of the logical bit. Straightforward integration with rapid single flux quantum logic is possible.

Goldobin, E.; Sickinger, H.; Weides, M.; Ruppelt, N.; Kohlstedt, H.; Kleiner, R.; Koelle, D.

2013-06-01

168

Geometry and Topology of String Junctions  

E-print Network

We study elliptic fibrations by analyzing suitable deformations of the fibrations and vanishing cycles. We introduce geometric string junctions and describe some of their properties. We show how the structure of the geometric string junctions is naturally related to the Lie algebra structures of the associated singularities. One application in physics is in F-theory, where our novel approach connecting deformations and Lie algebras describes the structure of generalized type IIB seven-branes and string junction states which end on them.

Grassi, Antonella; Shaneson, Julius L

2014-01-01

169

Gap Junctions Couple Astrocytes and Oligodendrocytes  

PubMed Central

In vertebrates, a family of related proteins called connexins form gap junctions (GJs), which are intercellular channels. In the central nervous system (CNS), GJs couple oligodendrocytes and astrocytes (O/A junctions) and adjacent astrocytes (A/A junctions), but not adjacent oligodendrocytes, forming a “glial syncytium.” Oligodendrocytes and astrocytes each express different connexins. Mutations of these connexin genes demonstrate that the proper functioning of myelin and oligodendrocytes requires the expression of these connexins. The physiological function of O/A and A/A junctions, however, remains to be illuminated. PMID:18236012

Orthmann-Murphy, Jennifer L.; Abrams, Charles K.; Scherer, Steven S.

2009-01-01

170

Inhibition of gap junction and adherens junction assembly by connexin and A-CAM antibodies  

Microsoft Academic Search

We examined the roles of the extracellular domains of a gap junction protein and a cell adhesion molecule in gap junction and adherens junction forma- tion by altering cell interactions with antibody Fab fragments. Using immunoblotting and immunocyto- chemistry we demonstrated that Novikoff cells con- tained the gap junction protein, cormexin43 (Cx43), and the cell adhesion molecule, A-CAM (N-cadherin). Cells

Rita A. Meyer; Dale W. Laird; Jean-Paul Revel; Ross G. Johnson

1992-01-01

171

Magnetic tunnel junction pattern technique  

NASA Astrophysics Data System (ADS)

We have developed a magnetic tunnel junction (MTJ) pattern technique that involves transforming the magnetic layer above the tunnel barrier in unwanted areas into an insulator, thus providing insulation between different MTJ devices without suffering common tunnel barrier shorting problems. With this technique, 90%-100% yielding MTJ devices have been observed. MTJ results using this process are superior to an etching based process. Switching distribution of patterned magnetic bits is also narrower using this novel technique. Process control and the ability to stop on the tunnel barrier have been demonstrated.

Chen, Eugene; Schwarz, Benjamin; Choi, Chang Ju; Kula, Witold; Wolfman, Jerome; Ounadjela, Kamel; Geha, Sam

2003-05-01

172

SHORT COMMUNICATION ISOLATION OF EPIDERMAL CELL PAIRS FROM AN INSECT, TENEBRIO MOLITOR, FOR DUAL WHOLE-CELL RECORDING OF LARGE-CONDUCT ANCE GAP-JUNCTIONAL CHANNELS  

Microsoft Academic Search

The segmented insect integument, composed of an epidermal monolayer and its cuticular secretion, is a paradigm for the study of pattern formation during development (Lawrence, 1992). Epidermal activity during development may be coordinated by the transfer of cytoplasmic molecules through cell-cell gap-junctional channels (reviewed in Caveney, 1985). Gap junctions within intact epidermal segments exhibit dynamic changes in their permeability properties

DENNIS CHURCHILL; STANLEY CAVENEY

173

Dbl3 drives Cdc42 signaling at the apical margin to regulate junction position and apical differentiation.  

PubMed

Epithelial cells develop morphologically characteristic apical domains that are bordered by tight junctions, the apical-lateral border. Cdc42 and its effector complex Par6-atypical protein kinase c (aPKC) regulate multiple steps during epithelial differentiation, but the mechanisms that mediate process-specific activation of Cdc42 to drive apical morphogenesis and activate the transition from junction formation to apical differentiation are poorly understood. Using a small interfering RNA screen, we identify Dbl3 as a guanine nucleotide exchange factor that is recruited by ezrin to the apical membrane, that is enriched at a marginal zone apical to tight junctions, and that drives spatially restricted Cdc42 activation, promoting apical differentiation. Dbl3 depletion did not affect junction formation but did affect epithelial morphogenesis and brush border formation. Conversely, expression of active Dbl3 drove process-specific activation of the Par6-aPKC pathway, stimulating the transition from junction formation to apical differentiation and domain expansion, as well as the positioning of tight junctions. Thus, Dbl3 drives Cdc42 signaling at the apical margin to regulate morphogenesis, apical-lateral border positioning, and apical differentiation. PMID:24379416

Zihni, Ceniz; Munro, Peter M G; Elbediwy, Ahmed; Keep, Nicholas H; Terry, Stephen J; Harris, John; Balda, Maria S; Matter, Karl

2014-01-01

174

Dbl3 drives Cdc42 signaling at the apical margin to regulate junction position and apical differentiation  

PubMed Central

Epithelial cells develop morphologically characteristic apical domains that are bordered by tight junctions, the apical–lateral border. Cdc42 and its effector complex Par6–atypical protein kinase c (aPKC) regulate multiple steps during epithelial differentiation, but the mechanisms that mediate process-specific activation of Cdc42 to drive apical morphogenesis and activate the transition from junction formation to apical differentiation are poorly understood. Using a small interfering RNA screen, we identify Dbl3 as a guanine nucleotide exchange factor that is recruited by ezrin to the apical membrane, that is enriched at a marginal zone apical to tight junctions, and that drives spatially restricted Cdc42 activation, promoting apical differentiation. Dbl3 depletion did not affect junction formation but did affect epithelial morphogenesis and brush border formation. Conversely, expression of active Dbl3 drove process-specific activation of the Par6–aPKC pathway, stimulating the transition from junction formation to apical differentiation and domain expansion, as well as the positioning of tight junctions. Thus, Dbl3 drives Cdc42 signaling at the apical margin to regulate morphogenesis, apical–lateral border positioning, and apical differentiation. PMID:24379416

Zihni, Ceniz; Munro, Peter M.G.; Elbediwy, Ahmed; Keep, Nicholas H.; Terry, Stephen J.; Harris, John

2014-01-01

175

Effect of Front-Side Silver Metallization on Underlying n+-p Junction in Multicrystalline Silicon Solar Cells: Preprint  

SciTech Connect

We report on the effect of front-side Ag metallization on the underlying n+-p junction of multicrystalline Si solar cells. The junction quality beneath the contacts was investigated by characterizing the uniformities of the electrostatic potential and doping concentration across the junction, using scanning Kelvin probe force microscopy and scanning capacitance microscopy. We investigated cells with a commercial Ag paste (DuPont PV159) and fired at furnace setting temperatures of 800 degrees, 840 degrees, and 930 degrees C, which results in actual cell temperatures ~100 degrees C lower than the setting temperature and the three cells being under-, optimal-, and over-fired. We found that the uniformity of the junction beneath the Ag contact was significantly degraded by the over-firing, whereas the junction retained good uniformity with the optimal- and under-fire temperatures. Further, Ag crystallites with widely distributed sizes from <100 nm to several ?m were found at the Ag/Si interface of the over-fired cell. Large crystallites were imaged as protrusions into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of the junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent recrystallization with incorporation of impurities in the Ag paste and with formation of crystallographic defects during quenching.

Jiang, C. S.; Li, Z. G.; Moutinho, H. R.; Liang, L.; Ionkin, A.; Al-Jassim, M. M.

2012-06-01

176

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

SciTech Connect

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 {approx} 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.

Cleland, A.N.

1991-04-01

177

Connexin 43 expression on peripheral blood eosinophils: role of gap junctions in transendothelial migration.  

PubMed

Eosinophils circulate in the blood and are recruited in tissues during allergic inflammation. Gap junctions mediate direct communication between adjacent cells and may represent a new way of communication between immune cells distinct from communication through cytokines and chemokines. We characterized the expression of connexin (Cx)43 by eosinophils isolated from atopic individuals using RT-PCR, Western blotting, and confocal microscopy and studied the biological functions of gap junctions on eosinophils. The formation of functional gap junctions was evaluated measuring dye transfer using flow cytometry. The role of gap junctions on eosinophil transendothelial migration was studied using the inhibitor 18-a-glycyrrhetinic acid. Peripheral blood eosinophils express Cx43 mRNA and protein. Cx43 is localized not only in the cytoplasm but also on the plasma membrane. The membrane impermeable dye BCECF transferred from eosinophils to epithelial or endothelial cells following coculture in a dose and time dependent fashion. The gap junction inhibitors 18-a-glycyrrhetinic acid and octanol did not have a significant effect on dye transfer but reduced dye exit from eosinophils. The gap junction inhibitor 18-a-glycyrrhetinic acid inhibited eosinophil transendothelial migration in a dose dependent manner. Thus, eosinophils from atopic individuals express Cx43 constitutively and Cx43 may play an important role in eosinophil transendothelial migration and function in sites of inflammation. PMID:25110696

Vliagoftis, Harissios; Ebeling, Cory; Ilarraza, Ramses; Mahmudi-Azer, Salahaddin; Abel, Melanie; Adamko, Darryl; Befus, A Dean; Moqbel, Redwan

2014-01-01

178

Dynamic control of slow water transport by aquaporin 0: implications for hydration and junction stability in the eye lens.  

PubMed

Aquaporin 0 (AQP0), the most abundant membrane protein in mammalian lens fiber cells, not only serves as the primary water channel in this tissue but also appears to mediate the formation of thin junctions between fiber cells. AQP0 is remarkably less water permeable than other aquaporins, but the structural basis and biological significance of this low permeability remain uncertain, as does the permeability of the protein in a reported junctional form. To address these issues, we performed molecular dynamics (MD) simulations of water transport through membrane-embedded AQP0 in both its (octameric) junctional and (tetrameric) nonjunctional forms. From our simulations, we measured an osmotic permeability for the nonjunctional form that agrees with experiment and found that the distinct dynamics of the conserved, lumen-protruding side chains of Tyr-23 and Tyr-149 modulate water passage, accounting for the slow permeation. The junctional and nonjunctional forms conducted water equivalently, in contrast to a previous suggestion based on static crystal structures that water conduction is lost on junction formation. Our analysis suggests that the low water permeability of AQP0 may help maintain the mechanical stability of the junction. We hypothesize that the structural features leading to low permeability may have evolved in part to allow AQP0 to form junctions that both conduct water and contribute to the organizational structure of the fiber cell tissue and microcirculation within it, as required to maintain transparency of the lens. PMID:18787121

Jensen, Morten Ø; Dror, Ron O; Xu, Huafeng; Borhani, David W; Arkin, Isaiah T; Eastwood, Michael P; Shaw, David E

2008-09-23

179

Atomic scale 0-pi transition in a high-Tc superconductor/ferromagnetic-insulator/high-T superconductor Josephson junction  

E-print Network

We study the Josephson transport in a high-Tc superconductor/ferromagnetic-insulator(FI)/high-Tc superconductor numerically. We found the formation of a pi-junction in such systems. More remarkably the ground state of such junction alternates between 0- and pi-states when thickness of FI is increasing by a single atomic layer. We propose an experimental setup for observing the atomic-scale 0-pi transition. Such FI-based pi-junctions can be used to implement highly-coherent quantum bits.

Shiro Kawabata; Yukio Tanaka; Yasuhiro Asano

2011-03-11

180

Automatic deployment of a 2-D geophone array for efficient ultra-shallow seismic imaging  

E-print Network

the efficiency of 3-D shallow seismic 53acquisition can have transformative implications in fields 54of study where 2-D surveying is used today. Environmental, 55geotechnical, engineering, hydrogeologic, sedimentologic, 56tectonic, glaciologic, and archaeologic...

Tsoflias, Georgios P.; Steeples, Don W.; Czarnecki, Gerard P.; Sloan, Steven D.; Eslick, Robert C.

2006-01-01

181

High-performance CMOS with oxidation-planarized twin tubs and one-mask sealed diffusion-junctions  

Microsoft Academic Search

Issues of submicron integration in vertical topography, junction silicide, and contact integrity are summarized. Examples include (1) high cost of twin-tub formation to achieve planarity at tub boundaries, (2) silicide-related nonuniformity or defects on shallow junctions, and (3) coverage of a TiN diffusion barrier layer at bottom corners of contact windows. We present a simple process to attack the issues.

C. T. Liu; H. Luftman; W. Lin; C. P. Chang; T. S. Yang; C. C. Fu; K. H. Lee; R. Liu; D. S. Yaney

1993-01-01

182

Crack arrest within teeth at the dentinoenamel junction caused by elastic modulus mismatch  

Microsoft Academic Search

Enamel and dentin compose the crowns of human teeth. They are joined at the dentinoenamel junction (DEJ) which is a very strong and well-bonded interface unlikely to fail within healthy teeth despite the formation of multiple cracks within enamel during a lifetime of exposure to masticatory forces. These cracks commonly are arrested when reaching the DEJ. The phenomenon of crack

Sabine Bechtle; Theo Fett; Gabriele Rizzi; Stefan Habelitz; Arndt Klocke; Gerold A. Schneider

2010-01-01

183

From Dislocation Junctions to Forest Hardening R. Madec, B. Devincre, and L. P. Kubin  

E-print Network

and strain hardening in fcc crystals are examined with emphasis on the process of junction formation the stability of plastic flow, is called strain hardening. Its physical origin is understood in terms crystals and therefore to improve the physical content of current models for strain harden- ing

Devincre, Benoit

184

Rho GTPase signaling regulates tight junction assembly and protects tight junctions during ATP depletion.  

PubMed

Tight junctions control paracellular permeability and cell polarity. Rho GTPase regulates tight junction assembly, and ATP depletion of Madin-Darby canine kidney (MDCK) cells (an in vitro model of renal ischemia) disrupts tight junctions. The relationship between Rho GTPase signaling and ATP depletion was examined. Rho inhibition resulted in decreased localization of zonula occludens-1 (ZO-1) and occludin at cell junctions; conversely, constitutive Rho signaling caused an accumulation of ZO-1 and occludin at cell junctions. Inhibiting Rho before ATP depletion resulted in more extensive loss of junctional components between transfected cells than control junctions, whereas cells expressing activated Rho better maintained junctions during ATP depletion than control cells. ATP depletion and Rho signaling altered phosphorylation signaling mechanisms. ZO-1 and occludin exhibited rapid decreases in phosphoamino acid content following ATP depletion, which was restored on recovery. Expression of Rho mutant proteins in MDCK cells also altered levels of occludin serine/threonine phosphorylation, indicating that occludin is a target for Rho signaling. We conclude that Rho GTPase signaling induces posttranslational effects on tight junction components. Our data also demonstrate that activating Rho signaling protects tight junctions from damage during ATP depletion. PMID:9730964

Gopalakrishnan, S; Raman, N; Atkinson, S J; Marrs, J A

1998-09-01

185

Electrostatic control of thermoelectricity in molecular junctions.  

PubMed

Molecular junctions hold significant promise for efficient and high-power-output thermoelectric energy conversion. Recent experiments have probed the thermoelectric properties of molecular junctions. However, electrostatic control of thermoelectric properties via a gate electrode has not been possible due to technical challenges in creating temperature differentials in three-terminal devices. Here, we show that extremely large temperature gradients (exceeding 1?×?10(9?)K?m(-1)) can be established in nanoscale gaps bridged by molecules, while simultaneously controlling their electronic structure via a gate electrode. Using this platform, we study prototypical Au-biphenyl-4,4'-dithiol-Au and Au-fullerene-Au junctions to demonstrate that the Seebeck coefficient and the electrical conductance of molecular junctions can be simultaneously increased by electrostatic control. Moreover, from our studies of fullerene junctions, we show that thermoelectric properties can be significantly enhanced when the dominant transport orbital is located close to the chemical potential (Fermi level) of the electrodes. These results illustrate the intimate relationship between the thermoelectric properties and charge transmission characteristics of molecular junctions and should enable systematic exploration of the recent computational predictions that promise extremely efficient thermoelectric energy conversion in molecular junctions. PMID:25282046

Kim, Youngsang; Jeong, Wonho; Kim, Kyeongtae; Lee, Woochul; Reddy, Pramod

2014-11-01

186

Palladium Electrodes for Molecular Tunnel Junctions  

PubMed Central

Gold has been the metal of choice for research on molecular tunneling junctions, but it is incompatible with CMOS fabrication because it forms deep level traps in silicon. Palladium electrodes do not contaminate silicon, and also give higher tunnel current signals in the molecular tunnel junctions we have studied. The result is cleaner signals in a recognition-tunneling junction that recognizes the four natural DNA bases as well as 5-methyl cytosine, with no spurious background signals. More than 75% of all the recorded signal peaks call the base correctly. PMID:23037952

Chang, Shuai; Sen, Suman; Zhang, Peiming; Gyarfas, Brett; Ashcroft, Brian; Lefkowitz, Steven; Peng, Hongbo; Lindsay, Stuart

2012-01-01

187

Molecular mechanism of double Holliday junction dissolution  

PubMed Central

Processing of homologous recombination intermediates is tightly coordinated to ensure that chromosomal integrity is maintained and tumorigenesis avoided. Decatenation of double Holliday junctions, for example, is catalysed by two enzymes that work in tight coordination and belong to the same ‘dissolvasome’ complex. Within the dissolvasome, the RecQ-like BLM helicase provides the translocase function for Holliday junction migration, while the topoisomerase III alpha-RMI1 subcomplex works as a proficient DNA decatenase, together resulting in double-Holliday-junction unlinking. Here, we review the available architectural and biochemical knowledge on the dissolvasome machinery, with a focus on the structural interplay between its components. PMID:25061510

2014-01-01

188

The myoendothelial junction: breaking through the matrix?  

PubMed

Within the vasculature, specialized cellular extensions from endothelium (and sometimes smooth muscle) protrude through the extracellular matrix where they interact with the opposing cell type. These structures, termed myoendothelial junctions, have been cited as a possible key element in the control of several vascular physiologies and pathologies. This review will discuss observations that have led to a focus on the myoendothelial junction as a cellular integration point in the vasculature for both homeostatic and pathological conditions and as a possible independent signaling entity. We will also highlight the need for novel approaches to studying the myoendothelial junction in order to comprehend the cellular biology associated with this structure. PMID:19330678

Heberlein, Katherine R; Straub, Adam C; Isakson, Brant E

2009-05-01

189

Thermoelectric efficiency of critical quantum junctions  

E-print Network

We derive the efficiency at maximal power of a scale-invariant (critical) quantum junction in exact form. Both Fermi and Bose statistics are considered. We show that time-reversal invariance is spontaneously broken. For fermions we implement a new mechanism for efficiency enhancement above the Curzon-Ahlborn bound, based on a shift of the particle energy in each heat reservoir, proportional to its temperature. In this setting fermionic junctions can even reach at maximal power the Carnot efficiency. The bosonic junctions at maximal power turn out to be less efficient then the fermionic ones.

Mihail Mintchev; Luca Santoni; Paul Sorba

2013-10-09

190

Molecular Junction Transport - Some Vibronic Effects  

NASA Astrophysics Data System (ADS)

The behavior of molecular transport junctions in the coherent tunneling (Landauer-Imry) regime is rapidly becoming understood. But vibronic effects characterize molecules, and understanding how they act in such junctions is a significant issue. This talk will deal with the role of both weak and strong vibronic interactions in molecular junctions. The weak mixing appears in IETS spectra, and can be handled by perturbation theory in the coherent tunneling limit. It provides some quantitative comparisons between calculation and experiment, And can clarify pathways for transport. But strong vibronic interaction requires a more elaborate analysis, and changes the mechanisms for transport. Hysteresis and switching behaviors will be discussed.

Ratner, Mark

2007-03-01

191

Capacitance extraction in arbitrarily diffused junction  

E-print Network

calculation, three nonlinear equations based upon a, one-dimensional model ol' the p-n junction by Poisson's equation are solved for depletion width. The capacitance density is then calculated from the depletion width. The two-dimensional sidewall and three... axis on top, logarithmic axis on bottom 24 30 31 32 16 The shape of the diffused junction Depletion regions of the bottom 17 The one-dimensional model of the emitter-base junction The meshes used to calculate the depletion width . 38 42...

Chung, Tae-Song

2012-06-07

192

ARP2/3-mediated junction-associated lamellipodia control VE-cadherin–based cell junction dynamics and maintain monolayer integrity  

PubMed Central

Maintenance and remodeling of endothelial cell junctions critically depend on the VE-cadherin/catenin complex and its interaction with the actin filament cytoskeleton. Here we demonstrate that local lack of vascular endothelial (VE)-cadherin at established cell junctions causes actin-driven and actin-related protein 2/3 complex (ARP2/3)–controlled lamellipodia to appear intermittently at those sites. Lamellipodia overlap the VE-cadherin–free adjacent plasma membranes and facilitate formation of new VE-cadherin adhesion sites, which quickly move into the junctions, driving VE-cadherin dynamics and remodeling. Inhibition of the ARP2/3 complex by expression of the N-WASP (V)CA domain or application of two ARP2/3 inhibitors, CK-548 and CK-666, blocks VE-cadherin dynamics and causes intercellular gaps. Furthermore, expression of carboxy-terminal–truncated VE-cadherin increases the number of ARP2/3-controlled lamellipodia, whereas overexpression of wild-type VE-cadherin largely blocks it and decreases cell motility. The data demonstrate a functional interrelationship between VE-cadherin–mediated cell adhesion and actin-driven, ARP2/3-controlled formation of new VE-cadherin adhesion sites via intermittently appearing lamellipodia at established cell junctions. This coordinated mechanism controls VE-cadherin dynamics and cell motility and maintains monolayer integrity, thus potentially being relevant in disease and angiogenesis. PMID:24227887

Taha, Abdallah Abu; Taha, Muna; Seebach, Jochen; Schnittler, Hans-J.

2014-01-01

193

Autonomic control and innervation of the atrioventricular junctional pacemaker  

E-print Network

the junctional rate, and parasympathetic and sympathetic com- ponents can be separated with atropine system; Junctional rhythm; Junctional pacemaker (Heart Rhythm 2007;4:1326­1335) © 2007 Heart Rhythm junction may be- come the pacemaker of the heart. Unlike the well-characterized sinoatrial node (SAN

194

ZnO based organic-inorganic hybrid p-n junction diode  

NASA Astrophysics Data System (ADS)

We have fabricated zinc oxide and metal phthalocyanine based hybrid p-n junction diodes using aluminum doped zinc oxide film as transparent conducting electrode. The current rectifying behavior of these hybrid diodes is similar to those of inorganic p-n junction diodes. The current-voltage measurement gives a rectification ratio of the order of 104 and a current density of 0.6mA/cm2. The formation of depletion region at the inorganic-organic interface has been established by the capacitance-voltage measurements.

Singh, Budhi; Ghosh, Subhasis

2013-02-01

195

Genetics Home Reference: Junctional epidermolysis bullosa  

MedlinePLUS

... erosions form in response to minor injury or friction, such as rubbing or scratching. Researchers classify junctional ... in the epidermis are fragile and easily damaged. Friction or other minor trauma can cause the skin ...

196

Semiconductor tunnel junction with enhancement layer  

DOEpatents

The incorporation of a pseudomorphic GaAsSb layer in a runnel diode structure affords a new degree of freedom in designing runnel junctions for p-n junction device interconnects. Previously only doping levels could be varied to control the tunneling properties. This invention uses the valence band alignment band of the GaAsSb with respect to the surrounding materials to greatly relax the doping requirements for tunneling.

Klem, John F. (Sandia Park, NM); Zolper, John C. (Albuquerque, NM)

1997-01-01

197

Spectroscopy Measurements of Magnesium Diboride Josephson Junctions  

NASA Astrophysics Data System (ADS)

MgB2 has the highest Tc of the conventional superconductors at 39K and exhibits two superconducting energy bands. This material is also inexpensive to produce and has been utilized in new designs for MRI, RF cavities, and Josephson junctions. We report results of recent spectroscopy and transport measurements of Josephson junctions made of MgB2 obtained from our collaborators. We investigate its transport characteristics at sub-kelvin temperatures as well as its responses to resonant microwave activation.

Mlack, J. T.; Lambert, J. G.; Carabello, S. A.; Thrailkill, Z. E.; Galwaduge, P. T.; Ramos, R. C.

2010-03-01

198

Expression of Tight Junction Protein Claudin-1 in Human Crescentic Glomerulonephritis  

PubMed Central

The origin of crescent forming cells in human glomerulonephritis (GN) remains unknown. Some animal studies demonstrated that parietal epithelial cells of Bowman's capsule (PECs) were the main component of proliferating cells and PEC-specific tight junction protein claudin-1 was expressed in crescentic lesions. We investigated the expression of claudin-1 in human GN. Immunohistochemistry for claudin-1 was performed on 17 kidney biopsy samples with crescent formation. Colocalization of claudin-1 with intracellular tight junction protein ZO-1 was also evaluated by immunofluorescence double staining. Claudin-1 is expressed mainly at the cell to cell contact site of proliferating cells in cellular crescentic lesions in patients with these forms of human GN. Small numbers of crescent forming cells showed extrajunctional localization of claudin-1. Colocalization of claudin-1 with ZO-1 was found at cell to cell contact sites of adjacent proliferating cells. In control samples, staining of claudin-1 was positive in PECs, but not in podocytes. Our findings suggest that claudin-1 contributes to crescent formation as a component of the tight junction protein complex that includes ZO-1. Co-localization of claudin-1 with ZO-1 implies the formation of functional tight junction complexes in crescentic lesions to prevent the interstitial damage caused by penetration of filtered molecules from Bowman's space. PMID:24868462

Koda, Ryo; Yoshino, Atsunori; Imanishi, Yuji; Kawamoto, Shinya; Ueda, Yoshihiko; Yaoita, Eishin; Kazama, Junichiro James; Narita, Ichiei; Takeda, Tetsuro

2014-01-01

199

E-cadherin is essential for in vivo epidermal barrier function by regulating tight junctions  

PubMed Central

Cadherin adhesion molecules are key determinants of morphogenesis and tissue architecture. Nevertheless, the molecular mechanisms responsible for the morphogenetic contributions of cadherins remain poorly understood in vivo. Besides supporting cell–cell adhesion, cadherins can affect a wide range of cellular functions that include activation of cell signalling pathways, regulation of the cytoskeleton and control of cell polarity. To determine the role of E-cadherin in stratified epithelium of the epidermis, we have conditionally inactivated its gene in mice. Here we show that loss of E-cadherin in the epidermis in vivo results in perinatal death of mice due to the inability to retain a functional epidermal water barrier. Absence of E-cadherin leads to improper localization of key tight junctional proteins, resulting in permeable tight junctions and thus altered epidermal resistance. In addition, both Rac and activated atypical PKC, crucial for tight junction formation, are mislocalized. Surprisingly, our results indicate that E-cadherin is specifically required for tight junction, but not desmosome, formation and this appears to involve signalling rather than cell contact formation. PMID:15775979

Tunggal, Judith A; Helfrich, Iris; Schmitz, Annika; Schwarz, Heinz; Gunzel, Dorothee; Fromm, Michael; Kemler, Rolf; Krieg, Thomas; Niessen, Carien M

2005-01-01

200

Pannexin channels are not gap junction hemichannels.  

PubMed

Pannexins, a class of membrane channels, bear significant sequence homology with the invertebrate gap junction proteins, innexins and more distant similarities in their membrane topologies and pharmacological sensitivities with the gap junction proteins, connexins. However, the functional role for the pannexin oligomers, or pannexons, is different from connexin oligomers, the connexons. Many pannexin publications have used the term "hemichannels" to describe pannexin oligomers while others use the term "channels" instead. This has led to confusion within the literature about the function of pannexins that promotes the idea that pannexons serve as gap junction hemichannels and thus have an assembly and functional state as gap junctional intercellular channels. Here we present the case that unlike the connexin gap junction intercellular channels, so far, pannexin oligomers have repeatedly been shown to be channels that are functional in single membranes, but not as intercellular channel in appositional membranes. Hence, they should be referred to as channels and not hemichannels. Thus, we advocate that in the absence of firm evidence that pannexins form gap junctions, the use of the term "hemichannel" be discontinued within the pannexin literature. PMID:21532340

Sosinsky, Gina E; Boassa, Daniela; Dermietzel, Rolf; Duffy, Heather S; Laird, Dale W; MacVicar, Brian; Naus, Christian C; Penuela, Silvia; Scemes, Eliana; Spray, David C; Thompson, Roger J; Zhao, Hong-Bo; Dahl, Gerhard

2011-01-01

201

Exercise regulation of intestinal tight junction proteins.  

PubMed

Gastrointestinal distress, such as diarrhoea, cramping, vomiting, nausea and gastric pain are common among athletes during training and competition. The mechanisms that cause these symptoms are not fully understood. The stress of heat and oxidative damage during exercise causes disruption to intestinal epithelial cell tight junction proteins resulting in increased permeability to luminal endotoxins. The endotoxin moves into the blood stream leading to a systemic immune response. Tight junction integrity is altered by the phosphoylation state of the proteins occludin and claudins, and may be regulated by the type of exercise performed. Prolonged exercise and high-intensity exercise lead to an increase in key phosphorylation enzymes that ultimately cause tight junction dysfunction, but the mechanisms are different. The purpose of this review is to (1) explain the function and physiology of tight junction regulation, (2) discuss the effects of prolonged and high-intensity exercise on tight junction permeability leading to gastrointestinal distress and (3) review agents that may increase or decrease tight junction integrity during exercise. PMID:23134759

Zuhl, Micah; Schneider, Suzanne; Lanphere, Katherine; Conn, Carole; Dokladny, Karol; Moseley, Pope

2014-06-01

202

Multi-junction solar cell device  

DOEpatents

A multi-junction solar cell device (10) is provided. The multi-junction solar cell device (10) comprises either two or three active solar cells connected in series in a monolithic structure. The multi-junction device (10) comprises a bottom active cell (20) having a single-crystal silicon substrate base and an emitter layer (23). The multi-junction device (10) further comprises one or two subsequent active cells each having a base layer (32) and an emitter layer (23) with interconnecting tunnel junctions between each active cell. At least one layer that forms each of the top and middle active cells is composed of a single-crystal III-V semiconductor alloy that is substantially lattice-matched to the silicon substrate (22). The polarity of the active p-n junction cells is either p-on-n or n-on-p. The present invention further includes a method for substantially lattice matching single-crystal III-V semiconductor layers with the silicon substrate (22) by including boron and/or nitrogen in the chemical structure of these layers.

Friedman, Daniel J. (Lakewood, CO); Geisz, John F. (Wheat Ridge, CO)

2007-12-18

203

Design and fabrication of internally shunted tantalum nitride barrier Josephson junctions for RSFQ logic applications  

NASA Astrophysics Data System (ADS)

Superconductor/normal-conductor/superconductor (SNS) junctions are the preferred choice for rapid single flux quantum logic (RSFQ) because of their internally shunted current-voltage (I-V) characteristics. Most implementations of SNS junctions have not shown an advantage over the widely used externally shunted Nb/AlOx/Nb tunnel junctions, mainly due to their low barrier resistivity resulting in extremely low I cRn product, a parameter that determines the circuit speed. The design rule of next generation RSFQ circuits requires ˜1 mum junction size, an IcRn of >500 muV, and an Ic of ˜100 muA. Assuming a barrier thickness of 25--100 nm, barrier material is required to have resistivity of ˜5--20 mO-cm. Many materials including semiconductors, metal/oxide composites and defective nitride materials undergo the metal-insulator transition. It is, however, not clear whether any of these barriers can be used to make junctions which support the large, uniform and reproducible critical current needed for RSFQ circuits. In particular, carrier dynamics and the percolative nature of carrier transport through materials near the metal-insulator transition are not well understood and their influence on the junction properties needs to be addressed. We have chosen to explore junctions with TaxN as the barrier because its resistivity can be readily tuned in the desired range by using enhanced nitrogen partial pressures during reactive growth and TaxN does not require the extreme levels of purity and epitaxy to be consistently produced. Our experimental and theoretical investigation discovered that the mechanism responsible for the wide range of resistivities produced can be attributed to the formation of tantalum vacancies (VTa). Being a penta-valent acceptor, V Ta will "freeze out" carriers and result in metal-insulator transition. Utilizing the near metal-insulator transition resistivity of Ta xN, NbN/TaxN/NbN sandwich junctions made on MgO substrates showed unexpectedly large IcR n products of >1 mV at 4.2 K. The high cost and limited size of MgO substrates prevented those junctions from being useful for industry. In order to design TaxN barrier junctions as a drop-in replacement for Nb/AlOx/Nb tunnel junctions in the existing fabrication lines, NbTiN/TaxN/NbTiN and Nb/TaxN/Nb sandwiches are fabricated on oxidized 100 mm diameter Si wafers. Nb0.62Ti0.38N is used as electrode because of the higher Tc and the lower penetration depth than the best epitaxial grown NbN. The junction properties, i.e. temperature dependence of IcRn and xin, and thickness dependence of Jc, are consistent with well-known SNS theories if a longer than expected normal metal coherence length is assumed. The junctions are found to have the desired Jc, Rn , and IcRn values for the next generation RSFQ technology. To develop a more suitable mathematical model for SNS junctions with a barrier near metal-insulator transition and to study the influence of free carrier dynamics in the barrier, the resistively shunted junction (RSJ) model was extended to incorporate a frequency dependent dielectric response. The new model is capable of including response of the free carriers, influence of excitation from shallow defects, very soft phonon modes, and boundary resistances.

Yu, Lei

204

MODULATION OF N-CADHERIN JUNCTIONS AND THEIR ROLE AS EPICENTERS OF DIFFERENTIATION-SPECIFIC ACTIN REGULATION IN THE DEVELOPING LENS  

PubMed Central

Extensive elongation of lens fiber cells is a central feature of lens morphogenesis. Our study investigates the role of N-cadherin junctions in this process in vivo. We investigate both the molecular players involved in N-cadherin junctional maturation and the subsequent function of these junctions as epicenters for the assembly of an actin cytoskeleton that drives morphogenesis. We present the first evidence of nascent cadherin junctions in vivo, and show they are a prominent feature along lateral interfaces of undifferentiated lens epithelial cells. Maturation of these N-cadherin junctions, required for lens cell differentiation, preceded organization of a cortical actin cytoskeleton along the cells’ lateral borders, but was linked to recruitment of ?-catenin and dephosphorylation of N-cadherin-linked ?-catenin. Biochemical analysis revealed differentiation-specific recruitment of actin regulators cortactin and Arp3 to maturing N-cadherin junctions of differentiating cells, linking N-cadherin junctional maturation with actin cytoskeletal assembly during fiber cell elongation. Blocking formation of mature N-cadherin junctions led to reduced association of ?-catenin with N-cadherin, prevented organization of actin along lateral borders of differentiating lens fiber cells and blocked their elongation. These studies provide a molecular link between N-cadherin junctions and the organization of an actin cytoskeleton that governs lens fiber cell morphogenesis in vivo. PMID:20969840

Leonard, Michelle; Zhang, Liping; Zhai, Ni; Cader, Ahmad; Chan, Yim; Nowak, Roberta B.; Fowler, Velia M.; Menko, A. Sue

2010-01-01

205

MicroRNA-205 targets tight junction-related proteins during urothelial cellular differentiation.  

PubMed

The mammalian bladder urothelium classified as basal, intermediate, and terminally differentiated umbrella cells offers one of the most effective permeability barrier functions known to exist in nature because of the formation of apical uroplakin plaques and tight junctions. To improve our understanding of urothelial differentiation, we analyzed the microRNA (miRNA) expression profiles of mouse urinary tissues and by TaqMan miRNA analysis of microdissected urothelial layers and in situ miRNA-specific hybridization to determine the dependence of these miRNAs on the differentiation stage. Our in situ hybridization studies revealed that miR-205 was enriched in the undifferentiated basal and intermediate cell layers. We then used a quantitative proteomics approach to identify miR-205 target genes in primary cultured urothelial cells subjected to antagomir-mediated knockdown of specific miRNAs. Twenty-four genes were reproducibly regulated by miR-205; eleven of them were annotated as cell junction- and tight junction-related molecules. Western blot analysis demonstrated that antagomir-induced silencing of miR-205 in primary cultured urothelial cells elevated the expression levels of Tjp1, Cgnl1, and Cdc42. Ectopic expression of miR-205 in MDCK cells inhibited the expression of tight junction proteins and the formation of tight junctions. miR-205- knockdown urothelial cells showed alterations in keratin synthesis and increases of uroplakin Ia and Ib, which are the urothelial differentiation products. These results suggest that miR-205 may contribute a role in regulation of urothelial differentiation by modulating the expression of tight junction-related molecules. PMID:24912853

Chung, Pei-Jung Katy; Chi, Lang-Ming; Chen, Chien-Lun; Liang, Chih-Lung; Lin, Chung-Tzu; Chang, Yu-Xun; Chen, Chun-Hsien; Chang, Yu-Sun

2014-09-01

206

Precursor configurations and post-rupture evolution of Ag-CO-Ag single-molecule junctions.  

PubMed

Experimental correlation analysis and first-principles theory are used to probe the structure and evolution of Ag-CO-Ag single-molecule junctions both before the formation and after the rupture of the junctions. Two dimensional correlation histograms and conditional histograms demonstrate that prior to the single-molecule bridge configuration the CO molecule is already bound parallel to the Ag single-atom contact. This molecular precursor configuration is accompanied by the opening of additional conductance channels compared to the single-channel transport in pure Ag monoatomic junctions. To investigate the post-rupture evolution of the junction we introduce a cross-correlation analysis between the opening and the subsequent closing conductance traces. This analysis implies that the molecule is bound rigidly to the apex of one electrode, and so the same single-molecule configuration is re-established as the junction is closed. The experimental results are confirmed by ab initio simulations of the evolution of contact geometries, transmission eigenvalues and scattering wavefunctions. PMID:25358380

Balogh, Zoltán; Visontai, Dávid; Makk, Péter; Gillemot, Katalin; Oroszlány, László; Pósa, László; Lambert, Colin; Halbritter, András

2014-12-21

207

Deficiency of triad junction and contraction in mutant skeletal muscle lacking junctophilin type 1.  

PubMed

In skeletal muscle excitation-contraction (E-C) coupling, the depolarization signal is converted from the intracellular Ca2+ store into Ca2+ release by functional coupling between the cell surface voltage sensor and the Ca2+ release channel on the sarcoplasmic reticulum (SR). The signal conversion occurs in the junctional membrane complex known as the triad junction, where the invaginated plasma membrane called the transverse-tubule (T-tubule) is pinched from both sides by SR membranes. Previous studies have suggested that junctophilins (JPs) contribute to the formation of the junctional membrane complexes by spanning the intracellular store membrane and interacting with the plasma membrane (PM) in excitable cells. Of the three JP subtypes, both type 1 (JP-1) and type 2 (JP-2) are abundantly expressed in skeletal muscle. To examine the physiological role of JP-1 in skeletal muscle, we generated mutant mice lacking JP-1. The JP-1 knockout mice showed no milk suckling and died shortly after birth. Ultrastructural analysis demonstrated that triad junctions were reduced in number, and that the SR was often structurally abnormal in the skeletal muscles of the mutant mice. The mutant muscle developed less contractile force (evoked by low-frequency electrical stimuli) and showed abnormal sensitivities to extracellular Ca2+. Our results indicate that JP-1 contributes to the construction of triad junctions and that it is essential for the efficiency of signal conversion during E-C coupling in skeletal muscle. PMID:11535622

Ito, K; Komazaki, S; Sasamoto, K; Yoshida, M; Nishi, M; Kitamura, K; Takeshima, H

2001-09-01

208

Electron trap level in a GaN nanorod p-n junction grown by molecular-beam epitaxy  

SciTech Connect

We have studied the electrical properties of a GaN nanorod p-n junction diode by deep level transient spectroscopy measurements. The p-n junction nanorods were patterned on a SiO{sub 2} substrate by using e-beam lithography. In order to confirm the formation of p-n junction, cathodoluminescence and current-voltage measurements, as a function of temperature, were made. The current-voltage curve exhibits strong temperature dependence, suggesting that thermionic emission over a barrier dominates. This barrier most likely corresponds to emission from a deep level in the band. The deep level appears to be an electron trap at Ec-0.40 eV below the conduction band with a capture cross section of 2.22x10 cm{sup 2} near the depletion region of the p-n junction.

Park, Y.S.; Park, C.M.; Park, C.J.; Cho, H.Y.; Lee, Seung Joo; Kang, T.W.; Lee, S.H.; Oh, Jae-Eung; Yoo, Kyung-Hwa; Son, Min-Soo [Quantum Functional Semiconductor Research Center, Dongguk University, Seoul 100-715 (Korea, Republic of) and Department of Physics, Dongguk University, Seoul 100-715 (Korea); School of Electrical and Computer Engineering, Hanyang University, Ansan 425-791 (Korea, Republic of); Department of Physics, Yeonse University, Seoul 120-749 (Korea, Republic of)

2006-05-08

209

Tight junctions are membrane microdomains.  

PubMed

Tight junctions (TJ) of polarized epithelial cells regulate barrier function at mucosal surfaces. Structural proteins of TJs include hyperphosphorylated occludin (HO) and the peripheral membrane protein, ZO-1. Since TJs are dynamically regulated, and lipid-modified signal transduction proteins localize to TJs, we considered the possibility that the TJ itself is composed of microdomains with unique structure. Differential detergent extraction and isopycnic sucrose density gradients were utilized to isolate TJ-enriched membranes from a polarized intestinal epithelial cell line, T84. Here we report that major pools of hyperphosphorylated occludin (HO) and ZO-1 are found in raft-like membrane microdomains with characteristics of the previously described detergent-insoluble glycolipid rafts (DIGs). Properties of such gradient fractions included Triton X-100 (TX-100) insolubility, light scattering at 600 nm, buoyant density of approximately 1.08 g/cm(3) and increased cholesterol content compared to high density fractions. Similar results were obtained using natural epithelium. Unlike the TJ proteins HO and ZO-1, other basolateral transmembrane proteins including E-cadherin, c-met and &bgr; 1 integrin were not increased in DIG-like fractions. Immunoprecipitation studies revealed coprecipitation of a pool of occludin with caveolin-1, a scaffolding protein abundant in DIGs. Coprecipitation results were supported by immunofluorescence and immunogold labeling studies demonstrating caveolin-1 localization in the apical membrane and focal colocalization with occludin in TJs. TJ disassembly by calcium chelation resulted in displacement of TJ proteins from the 'raft-like' compartment. Our findings suggest that raft-like compartments play an important role in the spatial organization of TJs and probably in regulation of paracellular permeability in epithelial cells. PMID:10769208

Nusrat, A; Parkos, C A; Verkade, P; Foley, C S; Liang, T W; Innis-Whitehouse, W; Eastburn, K K; Madara, J L

2000-05-01

210

Co-culture of two MDCK strains with distinct junctional protein expression: a model for intercellular junction rearrangement and cell sorting  

Microsoft Academic Search

Distinct epithelial MDCK cell strains displaying extremes in transepithelial electrical resistance (paracellular permeability) have been established in co-culture and the subsequent cellular behaviour and formation of junctional complexes investigated. After high-density seeding, MDCK strain I and II cells in co-culture are initially randomly distributed but subsequently sort themselves out in a time-dependent manner to form separate homotypic aggregates. The final

Carla B. Collares-Buzato; Mark A. Jepson; Gordon T. A. McEwan; Barry H. Hirst; Nicholas L. Simmons

1998-01-01

211

Two Classes of Gap Junction Channels Mediate Soma-Germline Interactions Essential for Germline Proliferation and Gametogenesis in Caenorhabditis elegans  

PubMed Central

In all animals examined, somatic cells of the gonad control multiple biological processes essential for germline development. Gap junction channels, composed of connexins in vertebrates and innexins in invertebrates, permit direct intercellular communication between cells and frequently form between somatic gonadal cells and germ cells. Gap junctions comprise hexameric hemichannels in apposing cells that dock to form channels for the exchange of small molecules. Here we report essential roles for two classes of gap junction channels, composed of five innexin proteins, in supporting the proliferation of germline stem cells and gametogenesis in the nematode Caenorhabditis elegans. Transmission electron microscopy of freeze-fracture replicas and fluorescence microscopy show that gap junctions between somatic cells and germ cells are more extensive than previously appreciated and are found throughout the gonad. One class of gap junctions, composed of INX-8 and INX-9 in the soma and INX-14 and INX-21 in the germ line, is required for the proliferation and differentiation of germline stem cells. Genetic epistasis experiments establish a role for these gap junction channels in germline proliferation independent of the glp-1/Notch pathway. A second class of gap junctions, composed of somatic INX-8 and INX-9 and germline INX-14 and INX-22, is required for the negative regulation of oocyte meiotic maturation. Rescue of gap junction channel formation in the stem cell niche rescues germline proliferation and uncovers a later channel requirement for embryonic viability. This analysis reveals gap junctions as a central organizing feature of many soma–germline interactions in C. elegans. PMID:25195067

Starich, Todd A.; Hall, David H.; Greenstein, David

2014-01-01

212

Two Classes of Gap Junction Channels Mediate Soma-Germline Interactions Essential for Germline Proliferation and Gametogenesis in Caenorhabditis elegans.  

PubMed

In all animals examined, somatic cells of the gonad control multiple biological processes essential for germline development. Gap junction channels, composed of connexins in vertebrates and innexins in invertebrates, permit direct intercellular communication between cells and frequently form between somatic gonadal cells and germ cells. Gap junctions comprise hexameric hemichannels in apposing cells that dock to form channels for the exchange of small molecules. Here we report essential roles for two classes of gap junction channels, composed of five innexin proteins, in supporting the proliferation of germline stem cells and gametogenesis in the nematode Caenorhabditis elegans. Transmission electron microscopy of freeze-fracture replicas and fluorescence microscopy show that gap junctions between somatic cells and germ cells are more extensive than previously appreciated and are found throughout the gonad. One class of gap junctions, composed of INX-8 and INX-9 in the soma and INX-14 and INX-21 in the germ line, is required for the proliferation and differentiation of germline stem cells. Genetic epistasis experiments establish a role for these gap junction channels in germline proliferation independent of the glp-1/Notch pathway. A second class of gap junctions, composed of somatic INX-8 and INX-9 and germline INX-14 and INX-22, is required for the negative regulation of oocyte meiotic maturation. Rescue of gap junction channel formation in the stem cell niche rescues germline proliferation and uncovers a later channel requirement for embryonic viability. This analysis reveals gap junctions as a central organizing feature of many soma-germline interactions in C. elegans. PMID:25195067

Starich, Todd A; Hall, David H; Greenstein, David

2014-11-01

213

The discovery of epidermal tight junctions.  

PubMed

It was previously thought that the skin barrier is composed singly by the stratum corneum. However, this concept was overturned by the report of Tsukita's group in 2002. They convinced us that tight junctions exist in the stratum granulosum of the epidermis, with the constituent proteins being occludin, claudin-1 and claudin-4. However, more than 30 years before this, Hashimoto et al. described the possible existence of tight junctions in the epidermis in 'Intercellular spaces of the human epidermis as demonstrated with lanthanum' in 1971. Dr. Hashimoto observed lanthanum nitrate-injected human skin by electron microscopy. He discovered that the injected lanthanum penetrated the intercellular spaces of the basal and spinous layers of the epidermis and then moved towards the skin surface until penetration was halted in the granular cell layer near the stratum corneum. He described the cell-to-cell adhesion structures that blocked the movement of lanthanum as 'truly tight junctions'. Thus, this was the first description of the existence of tight junctions in the epidermis. However, the presence of these structures was denied by others and was forgotten. Thanks to the discovery of claudin, the existence of tight junctions between epidermal keratinocytes was finally confirmed. It is interesting that Hashimoto's finding was eventually proved to be correct three decades later as a result of progress in molecular biology. This article encourages us to recognize the importance of careful observation in the molecular biology era. PMID:24673182

Ozawa, Toshiyuki; Sugawara, Koji; Tsuruta, Daisuke

2014-06-01

214

Holding Tight: Cell Junctions and Cancer Spread  

PubMed Central

Cell junctions are sites of intercellular adhesion that maintain the integrity of epithelial tissue and regulate signalling between cells. These adhesive junctions are comprised of protein complexes that serve to establish an intercellular cytoskeletal network for anchoring cells, in addition to regulating cell polarity, molecular transport and communication. The expression of cell adhesion molecules is tightly controlled and their downregulation is essential for epithelial-mesenchymal transition (EMT), a process that facilitates the generation of morphologically and functionally diverse cell types during embryogenesis. The characteristics of EMT are a loss of cell adhesion and increased cellular mobility. Hence, in addition to its normal role in development, dysregulated EMT has been linked to cancer progression and metastasis, the process whereby primary tumors migrate to invasive secondary sites in the body. This paper will review the current understanding of cell junctions and their role in cancer, with reference to the abnormal regulation of junction protein genes. The potential use of cell junction molecules as diagnostic and prognostic markers will also be discussed, as well as possible therapies for adhesive dysregulation. PMID:23450077

Knights, Alexander J.; Funnell, Alister P. W.; Crossley, Merlin; Pearson, Richard C. M.

2013-01-01

215

Methods for the fabrication of thermally stable magnetic tunnel junctions  

DOEpatents

Magnetic tunnel junctions and method for making the magnetic tunnel junctions are provided. The magnetic tunnel junctions are characterized by a tunnel barrier oxide layer sandwiched between two ferromagnetic layers. The methods used to fabricate the magnetic tunnel junctions are capable of completely and selectively oxidizing a tunnel junction precursor material using an oxidizing gas containing a mixture of gases to provide a tunnel junction oxide without oxidizing the adjacent ferromagnetic materials. In some embodiments the gas mixture is a mixture of CO and CO.sub.2 or a mixture of H.sub.2 and H.sub.2O.

Chang, Y. Austin (Middleton, WI); Yang, Jianhua J. (Madison, WI); Ladwig, Peter F. (Hutchinson, MN)

2009-08-25

216

Tunnel junctions, cantilevers, and potentials  

NASA Astrophysics Data System (ADS)

We have developed a process for making sub-micrometer dimensional cantilevers, clamped beams, and more complicate electro-mechanical structures that carry integrated electrical leads. Such objects are perhaps useful as test structures for connecting to and measuring the electrical properties of molecular sized objects, as high frequency electromechanical components for radio and microwave frequency applications, and as sensor components for studying the fluctuation physics of small machines. Our process uses two realigned electron-beam lithography steps, a thin film angled deposition system, and differential removal of sacrificial aluminum layers to produce freely suspended sub-micron electromechanical components. We have produced cantilevers and beams on a variety of substrates (silica, silicon, and poly-imide) and have produced insulating, conductive, and multi-layer mechanical structures. We have measured mechanical resonances in the 10 MHz range by electrostatically actuating the cantilevers while in a magnetic field (3500 gauss) and measuring the voltage that results across the front edge of the cantilever. Two structures are fabricated sharing a common ground so that a balanced detection technique can be used to eliminate background signals. Due to the square dependence of the electrostatic force on the voltage, they can be resonated by a drive voltage of 1/2 the natural frequency or at the natural frequency. Two separate attempts have been made to apply these resonators. First, a process was developed to integrate a tunnel junction with the cantilever. These devices can possibly be used for probing small-scale systems such as molecules. We have verified the exponential variation of the tunneling resistance with both substrate flex and electrostatic gating. Second, a novel gate structure was developed to create a double potential well for resonator motion. This is accomplished by placing a multilayer structure in front of the hairpin cantilever consisting two silver layers separated by a layer of aluminum oxide. By applying a voltage and measuring how the resonant frequency changes, the shape of the potential can be deduced. Ideally, the structure would produce a double potential well with well separation determined by geometry. The effect on the gate potentials on the resonant frequency was measured and compared to simple models.

Tanner, Shawn

217

Plasticity of Button-Like Junctions in the Endothelium of Airway Lymphatics in Development and Inflammation  

PubMed Central

Endothelial cells of initial lymphatics have discontinuous button-like junctions (buttons), unlike continuous zipper-like junctions (zippers) of collecting lymphatics and blood vessels. Buttons are thought to act as primary valves for fluid and cell entry into lymphatics. To learn when and how buttons form during development and whether they change in disease, we examined the appearance of buttons in mouse embryos and their plasticity in sustained inflammation. We found that endothelial cells of lymph sacs at embryonic day (E)12.5 and tracheal lymphatics at E16.5 were joined by zippers, not buttons. However, zippers in initial lymphatics decreased rapidly just before birth, as buttons appeared. The proportion of buttons increased from only 6% at E17.5 and 12% at E18.5 to 35% at birth, 50% at postnatal day (P)7, 90% at P28, and 100% at P70. In inflammation, zippers replaced buttons in airway lymphatics at 14 and 28 days after Mycoplasma pulmonis infection of the respiratory tract. The change in lymphatic junctions was reversed by dexamethasone but not by inhibition of vascular endothelial growth factor receptor-3 signaling by antibody mF4-31C1. Dexamethasone also promoted button formation during early postnatal development through a direct effect involving glucocorticoid receptor phosphorylation in lymphatic endothelial cells. These findings demonstrate the plasticity of intercellular junctions in lymphatics during development and inflammation and show that button formation can be promoted by glucocorticoid receptor signaling in lymphatic endothelial cells. PMID:22538088

Yao, Li-Chin; Baluk, Peter; Srinivasan, R. Sathish; Oliver, Guillermo; McDonald, Donald M.

2012-01-01

218

Membrane specialization at an insect myoneural junction.  

PubMed

Myoneural junctions were examined in the asynchronous basalar flight muscle of the beetle Pachnoda ephippiata. The outer surface of the postjunctional membrane exhibits an array of prominent projections spaced at approximately 200 A intervals which arise directly from the outer dense lamina of the plasma membrane and extend part way across the junctional cleft. The projections follow irregularities in the contour of the postjunctional membrane precisely and they end abruptly near the edge of the junctional region. No separation can be resolved between the projections and the underlying trilaminar plasma membrane after a variety of preparative methods, and the projections therefore appear to be a component part of the membrane. This specialization, which is distinctly different from that at desmosomes and hemidesmosomes, occurs nowhere else on the surface of the muscle and is interpreted as a mosaic of specialized membrane subunits which probably include the receptor sites for the transmitter. PMID:4752402

Rosenbluth, J

1973-10-01

219

MEMBRANE SPECIALIZATION AT AN INSECT MYONEURAL JUNCTION  

PubMed Central

Myoneural junctions were examined in the asynchronous basalar flight muscle of the beetle Pachnoda ephippiata. The outer surface of the postjunctional membrane exhibits an array of prominent projections spaced at ?200 Å intervals which arise directly from the outer dense lamina of the plasma membrane and extend part way across the junctional cleft. The projections follow irregularities in the contour of the postjunctional membrane precisely and they end abruptly near the edge of the junctional region. No separation can be resolved between the projections and the underlying trilaminar plasma membrane after a variety of preparative methods, and the projections therefore appear to be a component part of the membrane. This specialization, which is distinctly different from that at desmosomes and hemidesmosomes, occurs nowhere else on the surface of the muscle and is interpreted as a mosaic of specialized membrane subunits which probably include the receptor sites for the transmitter. PMID:4752402

Rosenbluth, Jack

1973-01-01

220

Molecular organization of tricellular tight junctions  

PubMed Central

When the apicolateral border of epithelial cells is compared with a polygon, its sides correspond to the apical junctional complex, where cell adhesion molecules assemble from the plasma membranes of two adjacent cells. On the other hand, its vertices correspond to tricellular contacts, where the corners of three cells meet. Vertebrate tricellular contacts have specialized structures of tight junctions, termed tricellular tight junctions (tTJs). tTJs were identified by electron microscopic observations more than 40 years ago, but have been largely forgotten in epithelial cell biology since then. The identification of tricellulin and angulin family proteins as tTJ-associated membrane proteins has enabled us to study tTJs in terms of not only the paracellular barrier function but also unknown characteristics of epithelial cell corners via molecular biological approaches. PMID:25097825

Furuse, Mikio; Izumi, Yasushi; Oda, Yukako; Higashi, Tomohito; Iwamoto, Noriko

2014-01-01

221

Photocurrent Measurements of Carbon Nanotube PN Junctions  

NASA Astrophysics Data System (ADS)

Gated p-n junctions in semiconducting nanotubes have recently drawn much attention for their electronic and optoelectronic characteristics [1,2,3]. We investigate the photocurrent response at a nanotube gated p-n junction using a focused laser illumination source. We find that the photocurrent at zero source-drain bias increases linearly with optical power for the component of light along the length of the nanotube. Scanned photocurrent imaging demonstrates that carrier generation occurs primarily between the p- and n- type segments of the device. Measurements in an optical cryostat down to 4K reveal large photoresponse and step-like structure in the reverse bias photocurrent. These results show that nanotube p-n junctions are highly sensitive, nanoscale photodetectors. [1] J.U. Lee et al, App. Phys. Lett. 85, 145 (2004). [2] J.U. Lee, App. Phys. Lett. 87, 073101 (2005). [3] K. Bosnick et al, App. Phys. Lett. 89, 163121 (2006).

Gabor, Nathaniel; Zhong, Zhaohui; Bosnick, Ken; Park, Jiwoong; McEuen, Paul

2007-03-01

222

Flotillin microdomains stabilize cadherins at cell-cell junctions.  

PubMed

Cadherins are essential in many fundamental processes and assemble at regions of cell-cell contact in large macromolecular complexes named adherens junctions. We have identified flotillin 1 and 2 as new partners of the cadherin complexes. We show that flotillins are localised at cell-cell junctions (CCJs) in a cadherin-dependent manner. Flotillins and cadherins are constitutively associated at the plasma membrane and their colocalisation at CCJ increases with CCJ maturation. Using three-dimensional structured illumination super-resolution microscopy, we found that cadherin and flotillin complexes are associated with F-actin bundles at CCJs. The knockdown of flotillins dramatically affected N- and E-cadherin recruitment at CCJs in mesenchymal and epithelial cell types and perturbed CCJ integrity and functionality. Moreover, we determined that flotillins are required for cadherin association with GM1-containing plasma membrane microdomains. This allows p120 catenin binding to the cadherin complex and its stabilization at CCJs. Altogether, these data demonstrate that flotillin microdomains are required for cadherin stabilization at CCJs and for the formation of functional CCJs. PMID:24046456

Guillaume, Emilie; Comunale, Franck; Do Khoa, Nam; Planchon, Damien; Bodin, Stéphane; Gauthier-Rouvière, Cécile

2013-11-15

223

Superconducting tunnel junctions as direct detectors for submillimeter astronomy  

NASA Astrophysics Data System (ADS)

This thesis presents measurements on the of performance of superconducting tunnel junctions (STJ) as direct detectors for submillimeter radiation. Over the past several decades, STJ's have been successfully implemented as energy-resolving detectors of X-ray and optical photons. This work extends their application to ultra-sensitive direct detection of photons near 100 GHz. The focus of this research is to integrate the detector with a readout that is sensitive, fast, and able to be scaled for use in large format arrays. We demonstrate the performance of a radio frequency single electron transistor (RF-SET) configured as a transimpedance current amplifier as one such readout. Unlike traditional semiconductor amplifiers, the RF-SET is compatible with cryogenic operation and naturally lends itself to frequency domain multiplexing. This research progressed to the invention of RF-STJ, whereby the same RF reflectometry as used in the RF-SET is applied directly to the detector junction. This results in a greatly simplified design that preserves many of the advantages of the RF-SET while achieving comparable sensitivity. These experiments culminate in calibration of the detector with an on-chip, mesoscopic noise source. Millimeter wave Johnson noise from a gold microbridge illuminates the detector in situ. This allows for direct measurement of the "optical" properties of the detector and its RF readout, including the response time, responsivity and sensitivity.

Teufel, John Daniel

224

Currents Induced by Injected Charge in Junction Detectors  

PubMed Central

The problem of drifting charge-induced currents is considered in order to predict the pulsed operational characteristics in photo- and particle-detectors with a junction controlled active area. The direct analysis of the field changes induced by drifting charge in the abrupt junction devices with a plane-parallel geometry of finite area electrodes is presented. The problem is solved using the one-dimensional approach. The models of the formation of the induced pulsed currents have been analyzed for the regimes of partial and full depletion. The obtained solutions for the current density contain expressions of a velocity field dependence on the applied voltage, location of the injected surface charge domain and carrier capture parameters. The drift component of this current coincides with Ramo's expression. It has been illustrated, that the synchronous action of carrier drift, trapping, generation and diffusion can lead to a vast variety of possible current pulse waveforms. Experimental illustrations of the current pulse variations determined by either the rather small or large carrier density within the photo-injected charge domain are presented, based on a study of Si detectors. PMID:24036586

Gaubas, Eugenijus; Ceponis, Tomas; Kalesinskas, Vidas

2013-01-01

225

Exploring Hot Gas at Junctions of Galaxy Filaments  

NASA Astrophysics Data System (ADS)

Because galaxies are forced to follow the strong gravitational potential created by the underlying cosmic web of the dark matter, their distribution reflects its filamentary structures. By identifying the filamentary structures, one can therefore recover a map of the network that drives structure formation. Filamentary junctions are regions of particular interest as they identify places where mergers and other interesting astrophysical phenomena have high chances to occur. We identified the galaxy filaments by our original method (Sousbie (2011) & Sousbie et al. (2011)) and X-ray pointing observations were conducted for the six fields locating in the junctions of the galaxy filaments where no specific diffuse X-ray emissions had previously been detected so far. We discovered significant X-ray signals in their images and spectra of the all regions. Spectral analysis demonstrated that six sources originate from diffuse emissions associated with optically bright galaxies, group-scale, or cluster-scale X-ray halos with kT˜1-4 keV, while the others are compact object origin. Interestingly, all of the newly discovered three intracluster media show peculiar features such as complex or elongated morphologies in X-ray and/or optical and hot spot involved in ongoing merger events (Kawahara et al. (2011) & Mitsuishi et al. (2014)). In this conference, results of follow-up radio observations for the merging groups as well as the details of the X-ray observations will be reported.

Mitsuishi, Ikuyuki; Yamasaki, Noriko; Kawahara, Hajime; Sekiya, Norio; Sasaki, Shin; Sousbie, Thierry

226

Generation of terahertz waves by a current in magnetic junctions  

NASA Astrophysics Data System (ADS)

The terahertz region of the electromagnetic spectrum (approximately 0.3-30 THz) is still insufficiently mastered primarily because of the absence of compact and controllable emitters (oscillators) and receivers (detectors) reliably operating in this range in a wide temperature range, including room temperature. The corresponding recent studies in this field, which were supported by the Russian Foundation for Basic Research, have been reviewed. New physical effects have been proposed and principles of the operation of terahertz devices based on these effects have been implemented. These effects refer to the physics of ferromagnetic and/or antiferromagnetic conducting layers assembled in micro- and nanostructures, which are called magnetic junctions. These effects are as follows: the formation of a quasiequilibrium distribution of current-injected electrons over the energy levels and the possibility of inverted population of levels, induction of the macroscopic magnetization by a spin-polarized current in an antiferromagnetic layer in the absence of external magnetic field, the appearance of current-induced contribution to antiferromagnetic resonance, and the experimental observation and study of the properties of terahertz radiation in ferromagnet-ferromagnet and ferromagnet-antiferromagnet junctions.

Gulyaev, Yu. V.; Zilberman, P. E.; Mikhailov, G. M.; Chigarev, S. G.

2014-02-01

227

Currents induced by injected charge in junction detectors.  

PubMed

The problem of drifting charge-induced currents is considered in order to predict the pulsed operational characteristics in photo-and particle-detectors with a junction controlled active area. The direct analysis of the field changes induced by drifting charge in the abrupt junction devices with a plane-parallel geometry of finite area electrodes is presented. The problem is solved using the one-dimensional approach. The models of the formation of the induced pulsed currents have been analyzed for the regimes of partial and full depletion. The obtained solutions for the current density contain expressions of a velocity field dependence on the applied voltage, location of the injected surface charge domain and carrier capture parameters. The drift component of this current coincides with Ramo's expression. It has been illustrated, that the synchronous action of carrier drift, trapping, generation and diffusion can lead to a vast variety of possible current pulse waveforms. Experimental illustrations of the current pulse variations determined by either the rather small or large carrier density within the photo-injected charge domain are presented, based on a study of Si detectors. PMID:24036586

Gaubas, Eugenijus; Ceponis, Tomas; Kalesinskas, Vidas

2013-01-01

228

Oxide tunnel junctions supporting a two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

The discovery of a two-dimensional electron gas (2DEG) at the interface between insulating oxides has led to a well-deserved level of excitement due to possible applications as “in-plane” all-oxide nanoelectronics. Here we expand the range of possibilities to the realm of “out-of-plane” nanoelectronics by examining such all-oxide heterostructures as barriers in tunnel junctions. As an example system we perform first-principles electronic structure and transport calculations of a tunnel junction with a [SrTiO3]4/[LaO]1/[SrTiO3]4 heterostructure tunneling barrier embedded between SrRuO3 electrodes. The presence of the LaO atomic layer induces the formation of a 2DEG within the tunneling barrier which acts as an extended 2D potential well perpendicular to the transport direction, providing a route for resonant tunneling. Our calculations demonstrate that the tunneling conductance in this system can be strongly enhanced compared to a pure SrTiO3 barrier due to resonant tunneling, but that lattice polarization effects play a significant role in determining this behavior. In addition we find that this resonant tunneling is highly selective of the orbital symmetry of the tunneling states due to the “orbital polarization” of the 2DEG. We also discuss how the properties of the 2DEG are affected by the presence of metal electrodes.

Burton, J. D.; Velev, J. P.; Tsymbal, E. Y.

2009-09-01

229

On the derivative discontinuity in molecular junctions  

NASA Astrophysics Data System (ADS)

Both the wave and particle aspects of the electron play essential roles in transport through single-molecule junctions. The wave character is implicit both in the Landauer formula used to understand nanoscale transport and in the very chemical bonds holding the junction together, while the particle aspect is manifested in phenomena such as Coulomb blockade and shot noise. The dominant computational paradigm for transport in single-molecule junctions involves local or semilocal approximations to density functional theory combined with nonequilibrium Green's functions. This approach does exceptionally well at describing the wave aspect of the electron, but fails to describe the particle aspect---due to the omission of the derivative discontinuity in the exchange-correlation potential that arises in the limit of vanishing lead-molecule coupling. To understand the role of the derivative discontinuity in molecular junctions, we investigated the transport and occupancy of a simple Anderson model of a molecular junction. We showedootnotetextJustin P. Bergfield, Zhenfei Liu, Kieron Burke, Charles A. Stafford, arXiv:1106.3104v2 that the exact single-particle Kohn-Sham potential of density functional theory reproduces the linear-response transport of the Anderson model exactly, despite the lack of a Kondo peak in its spectral function. Using Bethe ansatz techniques, we calculated this potential exactly for all coupling strengths, including the cross-over from mean-field behavior to charge quantization caused by the derivative discontinuity. The implications of our results for more complex molecular junctions will be discussed.

Stafford, Charles

2012-02-01

230

Progressive development of gap junctions during growth of human pancreatic duct cells (Capan-1) in vitro and in vivo.  

PubMed

Among their numerous functions, gap junctions play a crucial role in proliferation, differentiation and secretion processes, although their existence and potential role in ion secretion in human pancreatic ducts have yet to be established. To investigate the morphogenesis and the role of gap junctions in human pancreatic duct cells, the Capan-1 cell line maintained in culture or heterotransplanted into nude mice was employed as model system. Capan-1 cells polarize during their growth in vivo and in vitro forming duct-like structures. Furthermore in culture, after confluence, these cells form domes, which is indicative of ion exchange processes. After treatment with tannic acid and freeze-fracture, gap junctions were observed along the basolateral membranes of Capan-1 cells on electron microscopic examination. The presence of alkaline phosphatases on gap junctions was demonstrated cytoenzymatically. In addition, cell-to-cell communication was visualized by microinjection of Lucifer yellow. During differentiation of Capan-1 cells in culture, the frequency of intercellular communications increased markedly over the period (days 11-13) when the cells form duct-like structures. The increase in gap junctions was demonstrated by analysis of the polarized cells organized in duct-like structures that are commonly observed in the tumors formed by heterotransplantation of Capan-1 cells into nude mice. Furthermore, gap junctions associated with tight junctions were also observed in the cells forming such structures. The role of gap junctions in ion exchange was evaluated by counting the number of domes in cultures treated with heptanol. Heptanol (an uncoupling agent of gap junction communication) completely inhibited dome formation in a reversible way, and reduced the frequency of intracellular communications by 44%. These results suggest that the gap junctions expressed by Capan-1 cells are involved in ion secretion by the human cancerous pancreatic duct cell line, Capan-1. In the present study, we show that: i) the expression of gap junctions is linked to development of the spatial conformation of the cells; and ii) gap junctions may be involved in ion secretion. PMID:8785517

Monzat, V; Fanjul, M; Leclerc, C; Palévody, C; Briand, J P; Jarry-Guichard, T; Gabrion, J; Moreau, M; Hollande, E

1995-01-01

231

Dynamical properties of high-temperature-superconductor granular bridge junctions: Inhomogeneous Josephson-junction-array model  

SciTech Connect

As an attempt to understand the dynamical behavior of the high-temperature-superconductor (HTSC) granular bridge junction, we model the granular HTSC bridge junction consisting of many small grains inside by an inhomogeneous Josephson junction array, i.e., randomly arranged Josephson junction arrays (JJA). To describe randomly distributed critical currents between the grains inside the HTSC granular bridge junction, we chose various possible configurations in {l_brace}{ital I}{sub {ital ij}}{sup {ital c}}{r_brace} and {l_brace}{ital R}{sub {ital ij}}{r_brace} for the one-dimensional (1D) and 2D inhomogeneous Josephson junctions, and calculated the current-voltage ({ital IV}) characteristics and self-radiation spectral densities of the 1D and 2D inhomogeneous Josephson junctions. As a result, depending upon the distribution of critical currents and shunted resistances, it is found that there are large variations of {ital IV} characteristics. In contrast to the appearance of giant Shapiro steps in the regular ordered array, such Shapiro steps disappear in the case of the disordered JJA due to the increased randomness in the distribution of critical currents. On the contrary, however, when there exists a correlation between critical currents and resistances, i.e., a constant Josephson voltage, {ital I}{sub {ital ij}}{sup {ital c}}{ital R}{sub {ital ij}}={ital V}{sub {ital J}} (constant), the fundamental Shapiro step emerges despite the disordered distribution of {ital I}{sub {ital ij}}{sup {ital c}}. The relevance of this model to the HTSC granular bridge junctions is discussed. In particular, experimentally observed dynamical behaviors of the HTSC granular bridge junctions are shown to be closely related to the case of the correlated distribution with constant Josephson voltage. {copyright} {ital 1996 The American Physical Society.}

Lee, J.; Lee, S.; Yu, J.; Park, G. [Department of Physics, Sogang University, Seoul 121-742 (Korea)] [Department of Physics, Sogang University, Seoul 121-742 (Korea)

1996-02-01

232

Magnetic Josephson junctions with noncentrosymmetric superconductors  

NASA Astrophysics Data System (ADS)

We study the dc Josephson effect in a clean noncentrosymmetric superconductor/ferromagnet/noncentro-symmetric superconductor junction within the quasiclassical theory of superconductivity. By considering charge and spin currents, we show that in such junctions an exotic Josephson effect can take place, depending on the superconducting pairing state and spin polarization direction. We focus on the importance of spin-triplet/spin-singlet gaps ratio in such systems showing that its value is related to the existence of even and odd high-order harmonics in the charge and spin current-phase relations, and to the possibility of 0-? transitions.

Rahnavard, Yousef; Manske, Dirk; Annunziata, Gaetano

2014-06-01

233

Thermoelectricity and transmission eigenchannels in buckyball junctions  

NASA Astrophysics Data System (ADS)

Transmission through nanoscale junctions consisting of a single Buckminsterfullerene molecule between two Pt or Au electrodes is investigated in the Coulomb blockade regime using the nonequilibrium Green's function approach. The Green's function of the buckyball is calculated in the isolated-resonance approximation, including the degenerate HOMO and LUMO orbitals. Electron-electron interactions were included in a constant-interaction model derived from ?-electron effective field theory. For junctions with Pt electrodes, we find two transmission channels (despite the 5-fold degenerate HOMO and 3-fold degenerate LUMO resonances) and a positive thermopower. For Au electrodes, the thermopower is strongly affected by quantum interference, and we find just one transmission channel.

Stefferson, Michael; Hudson, Jarred; Barr, Joshua; Bergfield, Justin; Stafford, Charles

2012-02-01

234

Deficiency of Transcription Factor Brn4 Disrupts Cochlear Gap Junction Plaques in a Model of DFN3 Non-Syndromic Deafness  

PubMed Central

Brn4, which encodes a POU transcription factor, is the gene responsible for DFN3, an X chromosome–linked, non-syndromic type of hearing loss. Brn4-deficient mice have a low endocochlear potential (EP), hearing loss, and ultrastructural alterations in spiral ligament fibrocytes, however the molecular pathology through which Brn4 deficiency causes low EP is still unclear. Mutations in the Gjb2 and Gjb6 genes encoding the gap junction proteins connexin26 (Cx26) and connexin30 (Cx30) genes, respectively, which encode gap junction proteins and are expressed in cochlear fibrocytes and non-sensory epithelial cells (i.e., cochlear supporting cells) to maintain the proper EP, are responsible for hereditary sensorineural deafness. It has been hypothesized that the gap junction in the cochlea provides an intercellular passage by which K+ is transported to maintain the EP at the high level necessary for sensory hair cell excitation. Here we analyzed the formation of gap junction plaques in cochlear supporting cells of Brn4-deficient mice at different stages by confocal microscopy and three-dimensional graphic reconstructions. Gap junctions from control mice, which are composed mainly of Cx26 and Cx30, formed linear plaques along the cell-cell junction sites with adjacent cells. These plaques formed pentagonal or hexagonal outlines of the normal inner sulcus cells and border cells. Gap junction plaques in Brn4-deficient mice did not, however, show the normal linear structure but instead formed small spots around the cell-cell junction sites. Gap junction lengths were significantly shorter, and the level of Cx26 and Cx30 was significantly reduced in Brn4-deficient mice compared with littermate controls. Thus the Brn4 mutation affected the assembly and localization of gap junction proteins at the cell borders of cochlear supporting cells, suggesting that Brn4 substantially contributes to cochlear gap junction properties to maintain the proper EP in cochleae, similar to connexin-related deafness. PMID:25259580

Kidokoro, Yoshinobu; Karasawa, Keiko; Minowa, Osamu; Sugitani, Yoshinobu; Noda, Tetsuo; Ikeda, Katsuhisa; Kamiya, Kazusaku

2014-01-01

235

Noise and superconducting transition in self-heated tunnel junctions  

SciTech Connect

Distinctive structure in the tunneling characteristics of junctions having a superconducting electrode arises at a bias V/sub 0/ where junction dissipation is sufficient to drive the electrode normal. While details of this structure are dependent upon junction-bath thermal linkage, in all cases a marked increase of junction conductance sigma(V) = dI/dV occurs at V/sub 0/ and this increase reflects an excess current at the superconducting-normal phase transition. In the case of Pb electrode junctions the transition in both normal and superfluid He occurs when junction dissipation triggers film boiling in the liquid. We discuss phase transition-induced tunneling structure, junction noise, and excess current for Pb electrode junctions in different thermal environments and consider the implications for tunneling spectroscopy and Josephson device applications.

Will, T.A.; Adler, J.G.

1983-10-01

236

Stabilization of Ion Concentration Polarization Using a Heterogeneous Nanoporous Junction  

E-print Network

We demonstrate a recycled ion-flux through heterogeneous nanoporous junctions, which induce stable ion concentration polarization with an electric field. The nanoporous junctions are based on integration of ionic hydrogels ...

Kim, Pilnam

237

An ab-initio analysis of bimetallic oligoaniline molecular junctions  

E-print Network

The electron transport characteristics of Oligoaniline molecular junctions terminated with thiol-ends are analyzed with the density functional theory and the Green's function approach. The molecular junction consists of an Oligoaniline molecule...

Wang, Michael Wei-Lueng

2007-09-17

238

A pump-independent function of the Na,K-ATPase is required for epithelial junction function and tracheal tube-size control  

PubMed Central

The heterodimeric Na,K-ATPase has been implicated in vertebrate and invertebrate epithelial cell junctions, morphogenesis and oncogenesis, but the mechanisms involved are unclear. We previously showed that the Drosophila Na,K-ATPase is required for septate junction (SJ) formation and that of the three ?-subunit loci, only Nrv2 isoforms support epithelial SJ barrier function and tracheal tube-size control. Here we show that Nrv1 is endogenously co-expressed with Nrv2 in the epidermis and tracheal system, but Nrv1 has a basolateral localization and appears to be excluded from the Nrv2-containing SJs. When the normally neuronal Nrv3 is expressed in epithelial cells, it does not associate with SJs. Thus, the ?-subunit is a key determinant of Na,K-ATPase subcellular localization as well as function. However, localization of the Na,K-ATPase to SJs is not sufficient for junctional activity because although several Nrv2/Nrv3 chimeric ?-subunits localize to SJs, only those containing the extracellular domain of Nrv2 have junctional activity. Junctional activity is also specific to different ?-subunit isoforms, with only some isoforms from the major ?-subunit locus being able to provide full barrier function and produce normal tracheal tubes. Importantly, mutations predicted to inactivate ATP? catalytic function do not compromise junctional activity, demonstrating that the Drosophila Na,K-ATPase has an ion-pump-independent role in junction formation and tracheal morphogenesis. These results define new functions for the intensively studied Na,K-ATPase. Strikingly, the rat ?1 isoform has full junctional activity and can rescue Atp?-null mutants to viability, suggesting that the Na,K-ATPase has an evolutionarily conserved role in junction formation and function. PMID:17164420

Paul, Sarah M.; Palladino, Michael J.; Beitel, Greg J.

2007-01-01

239

A pump-independent function of the Na,K-ATPase is required for epithelial junction function and tracheal tube-size control.  

PubMed

The heterodimeric Na,K-ATPase has been implicated in vertebrate and invertebrate epithelial cell junctions, morphogenesis and oncogenesis, but the mechanisms involved are unclear. We previously showed that the Drosophila Na,K-ATPase is required for septate junction (SJ) formation and that of the three beta-subunit loci, only Nrv2 isoforms support epithelial SJ barrier function and tracheal tube-size control. Here we show that Nrv1 is endogenously co-expressed with Nrv2 in the epidermis and tracheal system, but Nrv1 has a basolateral localization and appears to be excluded from the Nrv2-containing SJs. When the normally neuronal Nrv3 is expressed in epithelial cells, it does not associate with SJs. Thus, the beta-subunit is a key determinant of Na,K-ATPase subcellular localization as well as function. However, localization of the Na,K-ATPase to SJs is not sufficient for junctional activity because although several Nrv2/Nrv3 chimeric beta-subunits localize to SJs, only those containing the extracellular domain of Nrv2 have junctional activity. Junctional activity is also specific to different alpha-subunit isoforms, with only some isoforms from the major alpha-subunit locus being able to provide full barrier function and produce normal tracheal tubes. Importantly, mutations predicted to inactivate ATPalpha catalytic function do not compromise junctional activity, demonstrating that the Drosophila Na,K-ATPase has an ion-pump-independent role in junction formation and tracheal morphogenesis. These results define new functions for the intensively studied Na,K-ATPase. Strikingly, the rat alpha1 isoform has full junctional activity and can rescue Atpalpha-null mutants to viability, suggesting that the Na,K-ATPase has an evolutionarily conserved role in junction formation and function. PMID:17164420

Paul, Sarah M; Palladino, Michael J; Beitel, Greg J

2007-01-01

240

Hybrid pn-junction solar cells based on layers of inorganic nanocrystals and organic semiconductors: optimization of layer thickness by considering the width of the depletion region.  

PubMed

We report the formation and characterization of hybrid pn-junction solar cells based on a layer of copper diffused silver indium disulfide (AgInS2@Cu) nanoparticles and another layer of copper phthalocyanine (CuPc) molecules. With copper diffusion in the nanocrystals, their optical absorption and hence the activity of the hybrid pn-junction solar cells was extended towards the near-IR region. To decrease the particle-to-particle separation for improved carrier transport through the inorganic layer, we replaced the long-chain ligands of copper-diffused nanocrystals in each monolayer with short-ones. Under illumination, the hybrid pn-junctions yielded a higher short-circuit current as compared to the combined contribution of the Schottky junctions based on the components. A wider depletion region at the interface between the two active layers in the pn-junction device as compared to that of the Schottky junctions has been considered to analyze the results. Capacitance-voltage characteristics under a dark condition supported such a hypothesis. We also determined the width of the depletion region in the two layers separately so that a pn-junction could be formed with a tailored thickness of the two materials. Such a "fully-depleted" device resulted in an improved photovoltaic performance, primarily due to lessening of the internal resistance of the hybrid pn-junction solar cells. PMID:24452695

Saha, Sudip K; Guchhait, Asim; Pal, Amlan J

2014-03-01

241

The Na+/K+ ATPase is required for septate junction function and epithelial tube-size control in the Drosophila tracheal system.  

PubMed

Although the correct architecture of epithelial tubes is crucial for the function of organs such as the lung, kidney and vascular system, little is known about the molecular mechanisms that control tube size. We show that mutations in the ATPalpha alpha and nrv2 beta subunits of the Na+/K+ ATPase cause Drosophila tracheal tubes to have increased lengths and expanded diameters. ATPalpha and nrv2 mutations also disrupt stable formation of septate junctions, structures with some functional and molecular similarities to vertebrate tight junctions. The Nrv2 beta subunit isoforms have unique tube size and junctional functions because Nrv2, but not other Drosophila Na+/K+ ATPase beta subunits, can rescue nrv2 mutant phenotypes. Mutations in known septate junctions genes cause the same tracheal tube-size defects as ATPalpha and nrv2 mutations, indicating that septate junctions have a previously unidentified role in epithelial tube-size control. Double mutant analyses suggest that tube-size control by septate junctions is mediated by at least two discernable pathways, although the paracellular diffusion barrier function does not appear to involved because tube-size control and diffusion barrier function are genetically separable. Together, our results demonstrate that specific isoforms of the Na+/K+ ATPase play a crucial role in septate junction function and that septate junctions have multiple distinct functions that regulate paracellular transport and epithelial tube size. PMID:12930776

Paul, Sarah M; Ternet, Melissa; Salvaterra, Paul M; Beitel, Greg J

2003-10-01

242

Connexin43 Mutation Causes Heterogeneous Gap Junction Loss and Sudden Infant Death  

PubMed Central

Background An estimated 10-15% of sudden infant death syndrome (SIDS) may stem from channelopathy-mediated lethal arrhythmias. Loss of the GJA1-encoded gap junction channel protein connexin43 (Cx43) is known to underlie formation of lethal arrhythmias. GJA1 mutations have been associated with cardiac diseases including atrial fibrillation. Therefore, GJA1 is a plausible candidate gene for premature sudden death. Methods and Results GJA1 open reading frame mutational analysis was performed using PCR, DHPLC, and direct DNA sequencing on DNA from 292 SIDS cases. Immunofluorescence and dual whole cell patch-clamp studies were performed to determine functionality of mutant gap junctions. Immunostaining for gap junction proteins was performed on SIDS-associated paraffin-embedded cardiac tissue. Two rare, novel missense mutations, E42K and S272P, were detected in 2 of 292 SIDS cases, a 2-month-old white male and a 3-month-old white female, respectively. Analysis of the E42K victim’s parental DNA demonstrated a de novo mutation. Both mutations involved highly conserved residues and were absent in over 1000 ethnic-matched reference alleles. Immunofluorescence demonstrated no trafficking abnormalities for either mutation and S272P demonstrated wildtype junctional conductance. However, junctional conductance measurements for the E42K mutation demonstrated a loss-of-function not rescued by wildtype. Moreover, the E42K victim cardiac tissue demonstrated a mosaic immunostaining pattern for Cx43 protein. Conclusions This study provides the first molecular and functional evidence implicating a GJA1 mutation as a novel pathogenic substrate for SIDS. E42K-Cx43 demonstrated a trafficking-independent reduction in junctional coupling in vitro as well as demonstrating a mosaic pattern of mutational DNA distribution in deceased cardiac tissue, suggesting a novel mechanism of Cx43-associated sudden death. PMID:22179534

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

2012-01-01

243

Aberrant chromosome morphology in human cells defective for Holliday junction resolution.  

PubMed

In somatic cells, Holliday junctions can be formed between sister chromatids during the recombinational repair of DNA breaks or after replication fork demise. A variety of processes act upon Holliday junctions to remove them from DNA, in events that are critical for proper chromosome segregation. In human cells, the BLM protein, inactivated in individuals with Bloom's syndrome, acts in combination with topoisomerase III?, RMI1 and RMI2 (BTR complex) to promote the dissolution of double Holliday junctions. Cells defective for BLM exhibit elevated levels of sister chromatid exchanges (SCEs) and patients with Bloom's syndrome develop a broad spectrum of early-onset cancers caused by chromosome instability. MUS81-EME1 (refs 4-7), SLX1-SLX4 (refs 8-11) and GEN1 (refs 12, 13) also process Holliday junctions but, in contrast to the BTR complex, do so by endonucleolytic cleavage. Here we deplete these nucleases from Bloom's syndrome cells to analyse human cells compromised for the known Holliday junction dissolution/resolution pathways. We show that depletion of MUS81 and GEN1, or SLX4 and GEN1, from Bloom's syndrome cells results in severe chromosome abnormalities, such that sister chromatids remain interlinked in a side-by-side arrangement and the chromosomes are elongated and segmented. Our results indicate that normally replicating human cells require Holliday junction processing activities to prevent sister chromatid entanglements and thereby ensure accurate chromosome condensation. This phenotype was not apparent when both MUS81 and SLX4 were depleted from Bloom's syndrome cells, suggesting that GEN1 can compensate for their absence. Additionally, we show that depletion of MUS81 or SLX4 reduces the high frequency of SCEs in Bloom's syndrome cells, indicating that MUS81 and SLX4 promote SCE formation, in events that may ultimately drive the chromosome instabilities that underpin early-onset cancers associated with Bloom's syndrome. PMID:21399624

Wechsler, Thomas; Newman, Scott; West, Stephen C

2011-03-31

244

The mechanical response of lithographically defined break junctions  

SciTech Connect

We present an experimental study on the mechanical response of lithographically defined break junctions by measuring atomic chain formation, tunneling traces and Gundlach oscillations. The calibration factor, i.e., the ratio between the electrode movement and the bending of the substrate, is found to be 2.5 times larger than expected from a simple mechanical model. This result is consistent with previous finite-element calculations. Comparing different samples, the mechanical response is found to be similar for electrode separations >4 A. However, for smaller electrode separations significant sample-to-sample variations appear. These variations are ascribed to differences in the shape of the two electrodes on the atomic scale which cannot be controlled by the fabrication process.

Huisman, E. H.; Bakker, F. L.; Wees, B. J. van [Physics of Nanodevices, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Trouwborst, M. L. [Physics of Nanodevices, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Kamerlingh Onnes Laboratorium, Leiden University, P.O. Box 9504, 2300 RA, Leiden (Netherlands); Molen, S. J. van der [Kamerlingh Onnes Laboratorium, Leiden University, P.O. Box 9504, 2300 RA, Leiden (Netherlands)

2011-05-15

245

INTRODUCTION Gap junctions are intercellular protein channels formed by  

E-print Network

INTRODUCTION Gap junctions are intercellular protein channels formed by 12 subunits of membrane. To date, gap junctions remain the only known ubiquitous conduits for the direct exchange of ions and metabolites between cells, and in this capacity they have been found throughout the metazoa. Gap junctions

Snyder, Scott A.

246

Are Modern Imaging Techniques Over Diagnosing Ureteropelvic Junction Obstruction?  

Microsoft Academic Search

Since the widespread use of real-time ultrasonography in the early 1980s, ureteropelvic junction obstruction has been diagnosed at earlier ages and prenatally on a presumptive basis. However, substantial controversy exists over the diagnosis and treatment of ureteropelvic junction obstruction. We conducted an epidemiological study to determine if modern imaging techniques are leading to the over diagnosis of ureteropelvic junction obstruction.

John S. Wiener; Gregor K. Emmert; Arthur W. Whitehurst; L. Richard Smith; Lowell R. King

1995-01-01

247

INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation  

E-print Network

1 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation Submitted to the Graduate;2 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS Abstract by Sajid Kabeer In0.53Ga0.47As tunnel-type dopant, exhibited a backward diode behavior. #12;4 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS

248

NMDA receptors regulate developmental gap junction uncoupling via CREB signaling  

Microsoft Academic Search

Signaling through gap junctions (electrical synapses) is important in the development of the mammalian central nervous system. Abundant between neurons during postnatal development, gap junction coupling subsequently decreases and remains low in the adult, confined to specific subsets of neurons. Here we report that developmental uncoupling of gap junctions in the rat hypothalamus in vivo and in vitro is associated

Harsha Arumugam; Xinhuai Liu; Paul J Colombo; Roderick A Corriveau; Andrei B Belousov

2005-01-01

249

Structurally graded core junctions in sandwich beams: fatigue loading conditions  

Microsoft Academic Search

Sandwich beams with inclusion of different core materials were the subject of the experimental study [Bozhevolnaya E, Thomsen OT. Structurally graded core junctions in sandwich beams: quasi-static analysis. Compos Struct, in press], which focused on the static performance of such sandwich elements. The concept of structurally graded core junctions, suggested in [Bozhevolnaya E, Thomsen OT. Structurally graded core junctions in

Elena Bozhevolnaya; Ole Thybo Thomsen

2005-01-01

250

Intercellular junctions in the human fetal membranes  

Microsoft Academic Search

Freeze-fracture replicas of the human reflected and placental amnion and chorion laeve at term were studied in order to give a systematic survey of the nature and extension of the intercellular junctions in the fetal membranes. No differences could be detected between the reflected and placental amniotic epithelium. In both the replicas never displayed plasma membrane differentiations typical of occluding

H. Bartels; T. Wang

1983-01-01

251

Axion mass estimates from resonant Josephson junctions  

E-print Network

Recently it has been proposed that dark matter axions from the galactic halo can produce a small Shapiro step-like signal in Josephson junctions whose Josephson frequency resonates with the axion mass [C. Beck, PRL 111, 231801 (2013)]. Here we show that the axion field equations in a voltage-driven Josephson junction environment allow for a nontrivial solution where the axion-induced electric current manifests itself as an oscillating supercurrent. The linear change of phase associated with this nontrivial solution implies the existence of a large magnetic field in a tiny surface area of the weak link region of the junction which makes incoming axions decay into microwave photons. We derive a condition for the design of Josephson junction experiments so that they can act as optimum axion detectors. Four independent recent experiments are discussed in this context. The observed Shapiro step anomalies of all four experiments consistently point towards an axion mass of $(110 \\pm 2)\\mu $eV. This mass value is com...

Beck, Christian

2014-01-01

252

Axion mass estimates from resonant Josephson junctions  

E-print Network

Recently it has been proposed that dark matter axions from the galactic halo can produce a small Shapiro step-like signal in Josephson junctions whose Josephson frequency resonates with the axion mass [C. Beck, PRL 111, 231801 (2013)]. Here we show that the axion field equations in a voltage-driven Josephson junction environment allow for a nontrivial solution where the axion-induced electric current manifests itself as an oscillating supercurrent. The linear change of phase associated with this nontrivial solution implies the formal existence of a large magnetic field in a tiny surface area of the weak link region of the junction which makes incoming axions decay into microwave photons. We derive a condition for the design of Josephson junction experiments so that they can act as optimum axion detectors. Four independent recent experiments are discussed in this context. The observed Shapiro step anomalies of all four experiments consistently point towards an axion mass of $(110 \\pm 2)\\mu $eV. This mass value is compatible with the recent BICEP2 results and implies that Peccei-Quinn symmetry breaking was taking place after inflation.

Christian Beck

2014-03-22

253

Lateral junction dynamics lead the way out.  

PubMed

Epithelial cell layers need to be tightly regulated to maintain their integrity and correct function. Cell integration into epithelial sheets is now shown to depend on the N-WASP-regulated stabilization of cortical F-actin, which generates distinct patterns of apical-lateral contractility at E-cadherin-based cell-cell junctions. PMID:24481041

Behrndt, Martin; Heisenberg, Carl-Philipp

2014-02-01

254

Thin Junction Trees Francis R. Bach  

E-print Network

with thin junction trees---models that are characterized by an upper bound on the size of the maximal involving low­order marginal or conditional probabilities--- e.g., naive independence models, trees­order depen­ dencies in data, either within the maximum entropy setting---in which features are se­ lected [9

Jordan, Michael I.

255

Thin Junction Trees Francis R. Bach  

E-print Network

with thin junction trees--models that are characterized by an upper bound on the size of the maximal cliques for their computational tractability and their relative immunity to overfitting. Thus models involving low-order marginal within the maximum entropy setting--in which features are se- lected [9, 16]--and the graphical model

Bach, Francis

256

Overdamped Josephson junctions for digital applications  

NASA Astrophysics Data System (ADS)

An interesting feature of Superconductor-Normal metal-Superconductor Josephson junctions for digital applications is due to their non-hysteretic current-voltage characteristics in a broad temperature range below Tc. This allows to design Single-Flux-Quantum (SFQ) cells without the need of external shunts. Two advantages can be drawn from this property: first the SFQ cells can be more compact which leads to a more integrated solution towards nano-devices and more complex circuits; second the absence of electrical parasitic elements associated with the wiring of resistors external to the Josephson junctions increases the performance of SFQ circuits, in particular regarding the ultimate speed of operation. For this purpose Superconductor-Normal metal-Insulator-Superconductor Nb/Al-AlOx/Nb Josephson junctions have been recently developed at INRiM with aluminum layer thicknesses between 30 and 100 nm. They exhibit non-hysteretic current-voltage characteristics with IcRn values higher than 0.5 mV in a broad temperature range and optimal Stewart McCumber parameters at 4.2 K for RSFQ applications. The main features of obtained SNIS junctions regarding digital applications are presented.

Febvre, P.; De Leo, N.; Fretto, M.; Sosso, A.; Belogolovskii, M.; Collot, R.; Lacquaniti, V.

2013-01-01

257

Etching Magnetic Tunnel Junction with Metal Etchers  

Microsoft Academic Search

Etch performances of inductory-coupled plasma (ICP) metal etchers with several gas systems are examined under constant ion energy condition to evaluate extendibility to the 300 mm wafer magnetic tunnel junction (MTJ) etch process. The ICP-Ar sputter etch affects little on magnetic properties, and shows about the same magnetoresistive (MR) ratio with conventional Ar ion milling. Major issue is the electrical

Keizo Kinoshita; Hiroaki Utsumi; Katsumi Suemitsu; Hiromitsu Hada; Tadahiko Sugibayashi

2010-01-01

258

Staphylococcus aureus-derived peptidoglycan induces Cx43 expression and functional gap junction intercellular communication in microglia  

PubMed Central

Gap junctions serve as intercellular conduits that allow the exchange of small molecular weight molecules (up to 1 kDa) including ions, metabolic precursors and second messengers. Microglia are capable of recognizing peptidoglycan (PGN) derived from the outer cell wall of Staphylococcus aureus, a prevalent CNS pathogen, and respond with the robust elaboration of numerous pro-inflammatory mediators. Based on recent reports demonstrating the ability of tumor necrosis factor-? and interferon-? to induce gap junction coupling in macrophages and microglia, it is possible that pro-inflammatory mediators released from PGN-activated microglia are capable of inducing microglial gap junction communication. In this study, we examined the effects of S. aureus-derived PGN on Cx43, the major connexin in microglial gap junction channels, and functional gap junction communication using single-cell microinjections of Lucifer yellow (LY). Exposure of primary mouse microglia to PGN led to a significant increase in Cx43 mRNA and protein expression. LY microinjection studies revealed that PGN-treated microglia were functionally coupled via gap junctions, the specificity of which was confirmed by the reversal of activation-induced dye coupling by the gap junction blocker 18-?-glycyrrhetinic acid. In contrast to PGN-activated microglia, unstimulated cells consistently failed to exhibit LY dye coupling. These results indicate that PGN stimulation can induce the formation of a functional microglial syncytium, suggesting that these cells may be capable of influencing neuroinflammatory responses in the context of CNS bacterial infections through gap junction intercellular communication. PMID:16190870

Garg, Sarita; Md. Syed, Mohsin; Kielian, Tammy

2008-01-01

259

Characterization of pure boron depositions integrated in silicon diodes for nanometer-deep junction applications  

Microsoft Academic Search

Doping technologies for formation of ultrashallow and highly-doped p+ junctions are continuously demanded to face the challenges in front-end processing that have emerged due to the aggressive downscaling of vertical dimensions for future semiconductor devices. As an alternative to implantations, current solutions are based on in-situ boron (B) doping during Si\\/SiGe chemical vapor deposition (CVD) by using diborane (B2H6) as

F. Sarubbi

2010-01-01

260

Inverted Three-Junction Tandem Thermophotovoltaic Modules  

NASA Technical Reports Server (NTRS)

An InGaAs-based three-junction (3J) tandem thermophotovoltaic (TPV) cell has been investigated to utilize more of the blackbody spectrum (from a 1,100 C general purpose heat source GPHS) efficiently. The tandem consists of three vertically stacked subcells, a 0.74-eV InGaAs cell, a 0.6- eV InGaAs cell, and a 0.55-eV InGaAs cell, as well as two interconnecting tunnel junctions. A greater than 20% TPV system efficiency was achieved by another group with a 1,040 C blackbody using a single-bandgap 0.6- eV InGaAs cell MIM (monolithic interconnected module) (30 lateral junctions) that delivered about 12 V/30 or 0.4 V/junction. It is expected that a three-bandgap tandem MIM will eventually have about 3 this voltage (1.15 V) and about half the current. A 4 A/cm2 would be generated by a single-bandgap 0.6-V InGaAs MIM, as opposed to the 2 A/cm2 available from the same spectrum when split among the three series-connected junctions in the tandem stack. This would then be about a 50% increase (3xVoc, 0.5xIsc) in output power if the proposed tandem replaced the single- bandgap MIM. The advantage of the innovation, if successful, would be a 50% increase in power conversion efficiency from radioisotope heat sources using existing thermophotovoltaics. Up to 50% more power would be generated for radioisotope GPHS deep space missions. This type of InGaAs multijunction stack could be used with terrestrial concentrator solar cells to increase efficiency from 41 to 45% or more.

Wojtczuk, Steven

2012-01-01

261

Hydrogen-evolution characteristics of NiMo-coated, radial junction, p-silicon microwire array photocathodes  

E-print Network

Hydrogen-evolution characteristics of Ni­Mo-coated, radial junction, n+ p-silicon microwire array for photoelectrochemical hydrogen evolution. The formation of an emitter layer on the microwires yielded significant with Pt as a catalyst for the hydrogen- evolution reaction (HER), have produced thermodynamically

Atwater, Harry

262

Highly reliable ag nanowire flexible transparent electrode with mechanically welded junctions.  

PubMed

Deformation behavior of the Ag nanowire flexible transparent electrode under bending strain is studied and results in a novel approach for highly reliable Ag nanowire network with mechanically welded junctions. Bending fatigue tests up to 500 000 cycles are used to evaluate the in situ resistance change while imposing fixed, uniform bending strain. In the initial stages of bending cycles, the thermally annealed Ag nanowire networks show a reduction in fractional resistance followed by a transient and steady-state increase at later stages of cycling. SEM analysis reveals that the initial reduction in resistance is caused by mechanical welding as a result of applied bending strain, and the increase in resistance at later stages of cycling is determined to be due to the failure at the thermally locked-in junctions. Based on the observations from this study, a new methodology for highly reliable Ag nanowire network is proposed: formation of Ag nanowire networks with no prior thermal annealing but localized junction formation through simple application of mechanical bending strain. The non-annealed, mechanically welded Ag nanowire network shows significantly enhanced cyclic reliability with essentially 0% increase in resistance due to effective formation of localized wire-to-wire contact. PMID:24789010

Hwang, Byungil; Shin, Hae-A-Seul; Kim, Taegeon; Joo, Young-Chang; Han, Seung Min

2014-08-01

263

Geologic map of the Grand Junction Quadrangle, Mesa County, Colorado  

USGS Publications Warehouse

This 1:24,000-scale geologic map of the Grand Junction 7.5' quadrangle, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of the stratigraphy, structure, and geologic hazards in the area of the junction of the Colorado River and the Gunnison River. Bedrock strata include the Upper Cretaceous Mancos Shale through the Lower Jurassic Wingate Sandstone units. Below the Mancos Shale, which floors the Grand Valley, the Upper and Lower(?)Cretaceous Dakota Formation and the Lower Cretaceous Burro Canyon Formation hold up much of the resistant northeast- dipping monocline along the northeast side of the Uncompahgre uplift. The impressive sequence of Jurassic strata below include the Brushy Basin, Salt Wash, and Tidwell Members of the Upper Jurassic Morrison Formation, the Middle Jurassic Wanakah Formation and informal 'board beds' unit and Slick Rock Member of the Entrada Formation, and the Lower Jurassic Kayenta Formation and Wingate Sandstone. The Upper Triassic Chinle Formation and Early Proterozoic meta-igneous gneiss and migmatitic meta- sedimentary rocks, which are exposed in the Colorado National Monument quadrangle to the west, do not crop out here. The monoclinal dip slope of the northeastern margin of the Uncompahgre uplift is apparently a Laramide structural feature. Unlike the southwest-dipping, high-angle reverse faults in the Proterozoic basement and s-shaped fault- propagation folds in the overlying strata found in the Colorado National Monument 7.5' quadrangle along the front of the uplift to the west, the monocline in the map area is unbroken except at two localities. One locality displays a small asymmetrical graben that drops strata to the southwest. This faulted character of the structure dies out to the northwest into an asymmetric fault-propagation fold that also drops strata to the southwest. Probably both parts of this structure are underlain by a northeast-dipping high-angle reverse fault. The other locality displays a second similar asymmetric fold. No evidence of post-Laramide tilting or uplift exists here, but the antecedent Unaweep Canyon, only 30 km to the south-southwest of the map area, provides clear evidence of Late Cenozoic, if not Pleistocene, uplift. The major geologic hazards in the area include large landslides associated with the dip-slope-underlain, smectite-rich Brushy Basin Member of the Morrison Formation and overlying Dakota and Burro Canyon Formations. Active landslides affect the southern bank of the Colorado River where undercutting by the river and smectitic clays in the Mancos trigger landslides. The Wanakah, Morrison, and Dakota Formations and the Mancos Shale create a significant hazard to houses and other structures by containing expansive smectitic clay. In addition to seasonal spring floods associated with the Colorado and Gunnison Rivers, a serious flash flood hazard associated with sudden summer thunderstorms threatens the intermittent washes that drain the dip slope of the monocline.

Scott, Robert B.; Carrara, Paul E.; Hood, William C.; Murray, Kyle E.

2002-01-01

264

Oligodendrocyte gap junction loss and disconnection from reactive astrocytes in multiple sclerosis gray matter.  

PubMed

Gap junctions are essential for glial cell function and have been increasingly implicated in multiple sclerosis (MS). Because increasing cortical abnormalities correlate with disease progression and cognitive dysfunction, we examined the expression of oligodendrocytic connexin32 (Cx32) and Cx47 and their astrocytic partners Cx30 and Cx43 in cortical lesions and normal-appearing gray matter (NAGM) in MS patients. Postmortem brain tissue samples from 9 MS cases were compared with 10 controls using real-time polymerase chain reaction, immunoblot, and immunohistochemical analyses. Connexin32 and Cx47 gap junction formation in oligodendrocytes was reduced within lesions, whereas Cx32 loss also extended to NAGM. In contrast, astrocytic Cx30 expression was increased within cortical lesions, whereas Cx43 was elevated in both lesions and NAGM. Diffuse microglial activation and marked astrogliotic changes accompanied these connexin abnormalities. Increased expression of Cx43 correlated with inflammatory load (r = 0.828, p = 0.042), whereas Cx32 expression correlated with longer disease duration and, therefore, milder course (r = 0.825, p = 0.043). Thus, there is a loss of intramyelin and intercellular oligodendrocyte gap junctions in MS gray matter lesions and NAGM, whereas interastrocytic gap junctions are increased, reflecting astrogliosis. These changes correlate with inflammation and disease duration and suggest that disconnection of oligodendrocytes from reactive astrocytes may play a role in failed remyelination and disease progression. PMID:25101702

Markoullis, Kyriaki; Sargiannidou, Irene; Schiza, Natasa; Roncaroli, Federico; Reynolds, Richard; Kleopa, Kleopas A

2014-09-01

265

The tight junction protein claudin-1 influences cranial neural crest cell emigration  

PubMed Central

The neural crest is a population of migratory cells that follows specific pathways during development, eventually differentiating to form parts of the face, heart, and peripheral nervous system, the latter of which includes contributions from placodal cells derived from the ectoderm. Stationary, premigratory neural crest cells acquire the capacity to migrate by undergoing an epithelial-to-mesenchymal transition that facilitates their emigration from the dorsal neural tube. This emigration involves, in part, the dismantling of cell-cell junctions, including apically localized tight junctions in the neuroepithelium. In this study, we have characterized the role of the transmembrane tight junction protein claudin-1 during neural crest and placode ontogeny. Our data indicate that claudin-1 is highly expressed in the developing neuroepithelium but is down-regulated in migratory neural crest cells, although expression persists in the ectoderm from which the placode cells arise. Depletion or overexpression of claudin-1 augments or reduces neural crest cell emigration, respectively, but does not impact the development of several cranial placodes. Taken together, our results reveal a novel function for a tight junction protein in the formation of migratory cranial neural crest cells in the developing vertebrate embryo. PMID:22771518

Fishwick, Katherine J.; Neiderer, Theresa; Jhingory, Sharon; Bronner, Marianne; Taneyhill, Lisa A.

2012-01-01

266

Functional dissociation of paracellular permeability and transepithelial electrical resistance and disruption of the apical- basolateral intramembrane diffusion barrier by expression of a mutant tight junction membrane protein  

PubMed Central

Tight junctions, the most apical of the intercellular junctions that connect individual cells in a epithelial sheet, are thought to form a seal that restricts paracellular and intramembrane diffusion. To analyze the functioning of tight junctions, we generated stable MDCK strain 2 cell lines expressing either full-length or COOH-terminally truncated chicken occludin, the only known transmembrane component of tight junctions. Confocal immunofluorescence and immunoelectron microscopy demonstrated that mutant occludin was incorporated into tight junctions but, in contrast to full-length chicken occludin, exhibited a discontinuous junctional staining pattern and also disrupted the continuous junctional ring formed by endogenous occludin. This rearrangement of occludin was not paralleled by apparent changes in the junctional morphology as seen by thin section electron microscopy nor apparent discontinuities of the junctional strands observed by freeze-fracture. Nevertheless, expression of both wild-type and mutant occludin induced increased transepithelial electrical resistance (TER). In contrast to TER, particularly the expression of COOH-terminally truncated occludin led to a severalfold increase in paracellular flux of small molecular weight tracers. Since the selectivity for size or different types of cations was unchanged, expression of wild-type and mutant occludin appears to have activated an existing mechanism that allows selective paracellular flux in the presence of electrically sealed tight junctions. Occludin is also involved in the formation of the apical/basolateral intramembrane diffusion barrier, since expression of the COOH-terminally truncated occludin was found to render MDCK cells incapable of maintaining a fluorescent lipid in a specifically labeled cell surface domain. PMID:8769425

1996-01-01

267

Observation of molecular level behavior in molecular electronic junction device  

NASA Astrophysics Data System (ADS)

In this dissertation, I utilize AFM based scanning probe measurement and surface enhanced Raman scattering based vibrational spectroscopic analysis to directly characterize topographic, electronic, and chemical properties of molecules confined in the local area of M3 junction to elucidate the molecular level behavior of molecular junction electronic devices. In the introduction, the characterization of molecular electronic devices with different types of metal-molecule-metal (M3) structures based upon self-assembled monolayers (SAMs) is reviewed. A background of the characterization methods I use in this dissertation, conducting probe atomic force microscopy (cp-AFM) and surface enhanced Raman spectroscopy (SERS), is provided in chapter 1. Several attempts are performed to create the ideal top metal contacts on SAMs by metal vapor phase deposition in order to prevent the metal penetration inducing critical defects of the molecular electronic devices. The scanning probe microscopy (SPM), such as cp-AFM, contact mode (c-) AFM and non-contact mode (nc-) AFM, in ultra high vacuum conditions are utilized to study the process of the metal-SAM interface construction in terms of the correlation between the morphological and electrical properties including the metal nucleation and filament generation as a function of the functionalization of long-chain alkane thiolate SAMs on Au. In chapter 2, the nascent condensation process of vapor phase Al deposition on inert and reactive SAMs are studied by SPM. The results of top deposition, penetration, and filament generation of deposited Al are discussed and compared to the results previously observed by spectroscopic measurements. Cp-AFM was shown to provide new insights into Al filament formation which has not been observed by conventional spectroscopic analysis. Additionally, the electronic characteristics of individual Al filaments are measured. Chapter 3 reveals SPM characterization of Au deposition onto --COOH terminated SAMs utilized with strong surface dipole-dipole intermolecular interaction based on hydrogen bonding and ionic bonding potentially preventing the metal penetration. The observed results are discussed with kinetic paths of metal atoms on each SAM including temporal vacancies controlled by the intermolecular interactions in SAM upon the comparison with the spectroscopic results previously reported. The results in chapter 2 and 3 strongly suggests that AFM based characterization technique is powerful tool especially for detecting molecular-size local phenomena in vapor phase metal deposition process, especially, the electric short-circuit filaments growing through SAMs, which may induce critical misinterpretation of M3 junction device properties. In Chapter 4, an altered metal deposition process on inert SAM with using a buffer layer is performed to diminish the kinetic energy of impinging metal atoms. SPM characterization reveals an abrupt metal-SAM interface without any metal penetration. Examined electric characteristics also revealed typical non-resonant tunneling characteristics of long chain alkane thiolate SAMs. In chapter 5, the buffer layer assisted growth process is used to prepare a nano particles-SAM pristine interface on SAMs to control the metal-SAM interaction in order to study the fundamental issue of chemical enhancement mechanism of SERS. Identical Au nanoparticles-SAM-Au M3 structures with different Au-SAM interactions reveal a large discrepancy of enhancement factors of ˜100 attributed to the chemical interaction. In chapter 6, Raman spectroscopy of M3 junction is applied to the characterization of molecular electronics devices. A crossed nanowire junction (X-nWJ) device is employed for in-situ electronic-spectroscopic simultaneous characterization using Raman spectroscopy. A detailed study reveals the multi-probe capability of X-nWJ for in-situ Raman and in-elastic electron tunneling spectroscopy (IETS) as vibrational spectroscopies to diagnose molecular electronic devices. In chapter 7, aniline oligomer (OAn) based redox SAMs are characterized b

Maitani, Masato

268

Refraction-type sonic crystal junction diode  

NASA Astrophysics Data System (ADS)

Unidirectional sound transmission across a junction of two square sonic crystals with different orientations and lattice constants is numerically investigated. Re-scaling and rotating the wave vectors through refractions across the air-first sonic crystal interface and the junction, respectively, facilitate coupling into the spatial modes of the second crystal. Unidirectional transmission, demonstrated through finite element method simulations, is accomplished between 10.4 kHz and 12.8 kHz. Transmission values to the right and left are greater than 60% and less than 1.0%, respectively, between 11.0 kHz and 12.4 kHz, resulting in a contrast ratio greater than 0.9.

Cicek, Ahmet; Adem Kaya, Olgun; Ulug, Bulent

2012-03-01

269

Topological ? Josephson junction in superconducting Rashba wires  

NASA Astrophysics Data System (ADS)

In this Rapid Communication we show that Rashba-based topological superconductor nanowires, where the spin-orbit coupling may change its sign, support three topological phases protected by chiral symmetry. When a superconducting phase gradient is applied over the interface of the two nontrivial phases, the Andreev spectrum is qualitatively phase shifted by ? compared to usual Majorana weak links. The topological ? junction has the striking property of exhibiting a maximum supercurrent in the vicinity of vanishing phase difference. Qualitative features of the junction are robust against disorder and magnetic fields violating chiral symmetry. The studied system could be realized by local gating of the wire or by an appropriate stacking of permanent magnets in synthetic Rashba systems.

Ojanen, Teemu

2013-03-01

270

Nonreciprocity in Active Josephson Junction Circuits  

NASA Astrophysics Data System (ADS)

This thesis work explores different ideas for realizing nonreciprocal photon dynamics using active parametric circuits based on Josephson junctions. The motivation stems from developing non-magnetic alternatives to existing nonreciprocal devices, invariably employing magnetic materials and fields and hence limited in their application potential for use with on-chip microwave superconducting circuits. The main idea rests on the fact the "pump" wave (or the carrier) in an active nonlinear system changes the phase of a small modulation signal just as the magnetic field rotates the polarization of the wave propagating in a Faraday medium. All the implementations discussed in this thesis draw from the basic idea of chaining together discrete parametric processes with an optimal phase difference between the respective pumps to realize nonreciprocity. Though discussed specifically for microwave applications using Josephson junctions as a platform, the ideas presented here are generic enough to be adopted for any nonlinear system implementing frequency mixing.

Kamal, Archana

271

Interface composition in magnetic tunnel junctions  

SciTech Connect

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.

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

2001-06-01

272

Crooked, Coiled and Crimpled are three Ly6-like proteins required for proper localization of septate junction components  

PubMed Central

Cellular junction formation is an elaborate process that is dependent on the regulated synthesis, assembly and membrane targeting of constituting components. Here, we report on three Drosophila Ly6-like proteins essential for septate junction (SJ) formation. SJs provide a paracellular diffusion barrier and appear molecularly and structurally similar to vertebrate paranodal septate junctions. We show that Crooked (Crok), a small GPI-anchored Ly6-like protein, is required for septa formation and barrier functions. In embryos that lack Crok, SJ components are produced but fail to accumulate at the plasma membrane. Crok is detected in intracellular puncta and acts tissue-autonomously, which suggests that it resides in intracellular vesicles to assist the cell surface localization of SJ components. In addition, we demonstrate that two related Ly6 proteins, Coiled (Cold) and Crimpled (Crim), are required for SJ formation and function in a tissue-autonomous manner, and that Cold also localizes to intracellular vesicles. Specifically, Crok and Cold are required for correct membrane trafficking of Neurexin IV, a central SJ component. The non-redundant requirement for Crok, Cold, Crim and Boudin (Bou; another Ly6 protein that was recently shown to be involved in SJ formation) suggests that members of this conserved family of proteins cooperate in the assembly of SJ components, possibly by promoting core SJ complex formation in intracellular compartments associated with membrane trafficking. PMID:20570942

Nilton, Anna; Oshima, Kenzi; Zare, Fariba; Byri, Sunitha; Nannmark, Ulf; Nyberg, Kevin G.; Fehon, Richard G.; Uv, Anne E.

2010-01-01

273

Double- and triple-barrier Josephson junctions  

NASA Astrophysics Data System (ADS)

A generalization of the semi-classical model describing the Josephson dynamics of tri-layer superconducting systems is given by assuming a constant non-null arbitrary superconducting phase for the inner electrode and the presence of inhomogeneities in the superconducting coupling between electrodes. Extension of the model to triple-barrier Josephson junctions is proposed. Integer and fractional Shapiro steps are predicted and their amplitudes are calculated.

De Luca, R.; Giordano, A.

2014-11-01

274

Synaptic junctional glycoconjugates from chick brain  

Microsoft Academic Search

Forebrains from day-old chicks were homogenized and fractionated by differential sedimentation and density gradient centrifugation to yield subcellular fractions. The synaptosomal plasma membrane fraction was further treated with Triton X-100 to yield subsynaptic membrane fractions including synaptic junctions. Glycoproteins from these subsynaptic membrane fractions were identified after separation by SDS-polyacrylamide gel electrophoresis by incubating the gel slabs with radioiodinated concanavalin

Joseph C. Webster; Jack D. Klingman

1980-01-01

275

Anatomy and development of the craniovertebral junction  

Microsoft Academic Search

The occipital bone is the upper end of the somatic spine, limited cranially by the tentorium. The bony craniovertebral junction\\u000a (caudal occiput, atlas, and axis) is interposed between the unsegmented occipital and the intersegmental spinal sclerotomes,\\u000a separated from the occiput and C3 by the intrasegmental clefts of O4 and C2 sclerotomes, respectively. It retains a primitive\\u000a segmental hypocentrum (anterior arch

Charles Raybaud

276

Tunneling anisotropic magnetoresistance of helimagnet tunnel junctions  

NASA Astrophysics Data System (ADS)

We theoretically investigate the angular- and spin-dependent transport in normal-metal/helical-multiferroic/ferromagnetic heterojunctions. We find a tunneling anisotropic magnetoresistance (TAMR) effect due to the spiral magnetic order in the tunnel junction and to an effective spin-orbit coupling induced by the topology of the localized magnetic moments in the multiferroic spacer. The predicted TAMR effect is efficiently controllable by an external electric field due to the magnetoelectric coupling.

Jia, Chenglong; Berakdar, Jamal

2010-02-01

277

An epitaxial ferroelectric tunnel junction on silicon.  

PubMed

Epitaxially grown functional perovskites on silicon (001) and the ferroelectricity of a 3.2 nm thick BaTiO3 barrier layer are demonstrated. The polarization-switching-induced change in tunneling resistance is measured to be two orders of magnitude. The obtained results suggest the possibility of integrating ferroelectric tunnel junctions as binary data storage media in non-volatile memory cells on a silicon platform. PMID:25200550

Li, Zhipeng; Guo, Xiao; Lu, Hui-Bin; Zhang, Zaoli; Song, Dongsheng; Cheng, Shaobo; Bosman, Michel; Zhu, Jing; Dong, Zhili; Zhu, Weiguang

2014-11-01

278

Quantum dynamics in the bosonic Josephson junction  

SciTech Connect

We employ a semiclassical picture to study dynamics in a bosonic Josephson junction with various initial conditions. Phase diffusion of coherent preparations in the Josephson regime is shown to depend on the initial relative phase between the two condensates. For initially incoherent condensates, we find a universal value for the buildup of coherence in the Josephson regime. In addition, we contrast two seemingly similar on-separatrix coherent preparations, finding striking differences in their convergence to classicality as the number of particles increases.

Chuchem, Maya; Cohen, Doron [Department of Physics, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 84105 (Israel); Smith-Mannschott, Katrina [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States); MPI for Dynamics and Self-Organization, Bunsenstrasse 10, D-37073 Goettingen (Germany); Hiller, Moritz [Physikalisches Institut, Albert-Ludwigs-Universitaet, Hermann-Herder-Strasse 3, D-79104 Freiburg (Germany); Kottos, Tsampikos [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States); Vardi, Amichay [Department of Chemistry, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 84105 (Israel); Institute for Theoretical Atomic, Molecular and Optical Physics, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)

2010-11-15

279

Pentacene-based photodiode with Schottky junction  

Microsoft Academic Search

We have fabricated a metal\\/organic semiconductor Schottky photodiode based on Al\\/pentacene junction. Since the energy band gap of thin solid pentacene was determined to be 1.82 eV, as characterized by direct absorption spectroscopy, we measured spectral photoresponses on our Schottky photodiode in the monochromatic light illumination range of 325–650 nm applying a reverse bias of ?2 V. The main features

Jiyoul Lee; D. K. Hwang; C. H. Park; S. S. Kim; Seongil Im

2004-01-01

280

Single-molecule junctions beyond electronic transport.  

PubMed

The idea of using individual molecules as active electronic components provided the impetus to develop a variety of experimental platforms to probe their electronic transport properties. Among these, single-molecule junctions in a metal-molecule-metal motif have contributed significantly to our fundamental understanding of the principles required to realize molecular-scale electronic components from resistive wires to reversible switches. The success of these techniques and the growing interest of other disciplines in single-molecule-level characterization are prompting new approaches to investigate metal-molecule-metal junctions with multiple probes. Going beyond electronic transport characterization, these new studies are highlighting both the fundamental and applied aspects of mechanical, optical and thermoelectric properties at the atomic and molecular scales. Furthermore, experimental demonstrations of quantum interference and manipulation of electronic and nuclear spins in single-molecule circuits are heralding new device concepts with no classical analogues. In this Review, we present the emerging methods being used to interrogate multiple properties in single molecule-based devices, detail how these measurements have advanced our understanding of the structure-function relationships in molecular junctions, and discuss the potential for future research and applications. PMID:23736215

Aradhya, Sriharsha V; Venkataraman, Latha

2013-06-01

281

LRP4 Is Critical for Neuromuscular Junction Maintenance.  

PubMed

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

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

2014-10-15

282

Morphological and functional characteristics of human gingival junctional epithelium  

PubMed Central

Background This study aims to observe the morphological characteristics and identify the function characteristics of junctional epithelium (JE) tissues and cultured JE cells. Methods Paraffin sections of human molar or premolar on the gingival buccolingual side were prepared from 6 subjects. HE staining and image analysis were performed to measure and compare the morphological difference among JE, oral gingival epithelium (OGE) and sulcular epithelium (SE). Immunohistochemistry was applied to detect the expression pattern of cytokeratin 5/6, 7, 8/18, 10/13, 16, 17, 19, and 20 in JE, OGE and SE. On the other hand, primary human JE and OGE cells were cultured in vitro. Cell identify was confirmed by histology and immunohistochemistry. In a co-culture model, TEM was used to observe the attachment formation between JE cells and tooth surface. Results Human JE was a unique tissue which was different from SE and OGE in morphology. Similarly, morphology of JE cells was also particular compared with OGE cells cultured in vitro. In addition, JE cells had a longer incubation period than OGE cells. Different expression of several CKs illustrated JE was in a characteristic of low differentiation and high regeneration. After being co-cultured for 14 d, multiple cell layers, basement membrane-like and hemidesmosome-like structures were appeared at the junction of JE cell membrane and tooth surface. Conclusions JE is a specially stratified epithelium with low differentiation and high regeneration ability in gingival tissue both in vivo and in vitro. In co-culture model, human JE cells can form basement membrane-like and hemidesmosome-like structures in about 2 weeks. PMID:24708739

2014-01-01

283

Electrochemical fabrication and characterization of 1 nm-scale molecular device junctions on gallium arsenic  

NASA Astrophysics Data System (ADS)

The fabrication of high-fidelity molecular junctions of 1 nm or less device length is a significant challenge due to penetration of the top contact through the molecular layer. Successively smaller device lengths allow for molecular layers to more strongly modulate semiconductor surface charge and conductivity through semiconductor depolarization; hence, it is of great interest to fabricate molecular junctions of device length scales of ˜1 nm and understand the ensuing transport mechanisms. In this study, electrochemical methods were investigated for the fabrication and characterization of molecular junctions of successively smaller device lengths on GaAs of successively varying substrate doping. Following the electrochemical impedance characterization of carboxylic acid terminal self-assembled monolayers (SAMs) of varying length on GaAs substrates of varying dopant concentration and type, copper complexation of carboxylic acid SAM-modified GaAs was used to nucleate a Cu film on the SAM through electroless deposition (ELD). Electrochemical, electron microscopy and electrical transport characterization of metal (ELD Cu) -- molecule (COOH terminal SAM) -- semiconductor (GaAs of varying dopant concentration) junction demonstrated the highly selective Cu deposition on carboxylic acid terminated GaAs, the strong dependence of ELD morphology on SAM order, and formation of high fidelity device junctions as judged by the absence of Cu penetration through the SAM for device lengths down to sub-nanometer scales. Electrical transport characteristics and electrochemical impedance methods were used to study the molecular layer induced semiconductor depolarization through understanding the transport barriers and elucidating the modifications to semiconductor band bending.

Camacho Alanis, Fernanda Adriana

284

Fabrication of a Schottky junction diode with direct growth graphene on silicon by a solid phase reaction  

NASA Astrophysics Data System (ADS)

We demonstrate fabrication of a Schottky junction diode with direct growth graphene on n-Si by the solid phase reaction approach. Metal-assisted crystallization of a-C thin film was performed to synthesize transfer-free graphene directly on a SiO2 patterned n-Si substrate. Graphene formation at the substrate and catalyst layer interface is achieved in presence of a Co catalytic and CoO carbon diffusion barrier layer. The as-synthesized material shows a linear current-voltage characteristic confirming the metallic behaviour of the graphene structure. The direct grown graphene on n-Si substrate creates a Schottky junction with a potential barrier of 0.44 eV and rectification diode characteristic. Our finding shows that the directly synthesized graphene on Si substrate by a solid phase reaction process can be a promising technique to fabricate an efficient Schottky junction device.

Kalita, Golap; Hirano, Ryo; Ayhan, Muhammed E.; Tanemura, Masaki

2013-11-01

285

Pulsed breakdown of 4H-SiC Schottky diodes terminated with a boron-implanted p-n junction  

SciTech Connect

Pulsed reverse current-voltage characteristics have been measured in the breakdown region for 1-kV 4H-SiC Schottky diodes terminated with a boron-implanted p-n junction. It was shown that the dynamic breakdown voltage of the diodes increases as the pulses become shorter. Owing to the homogeneous avalanche formation at the edge of the guard p-n junction and to the high differential resistance in the breakdown region, the diodes sustain without degradation a pulsed reverse voltage substantially exceeding the static breakdown threshold. Characteristic features of the pulsed breakdown are considered in relation to the specific properties of the boron-implanted guard p-n junction.

Ivanov, P. A., E-mail: Pavel.Ivanov@mail.ioffe.ru; Grekhov, I. V.; Potapov, A. S.; Samsonova, T. P. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2008-07-15

286

High-speed atomic force microscopy: cooperative adhesion and dynamic equilibrium of junctional microdomain membrane proteins.  

PubMed

Junctional microdomains, paradigm for membrane protein segregation in functional assemblies, in eye lens fiber cell membranes are constituted of lens-specific aquaporin-0 tetramers (AQP0(4)) and connexin (Cx) hexamers, termed connexons. Both proteins have double function to assure nutrition and mediate adhesion of lens cells. Here we use high-speed atomic force microscopy to examine microdomain protein dynamics at the single-molecule level. We found that the adhesion function of head-to-head associated AQP0(4) and Cx is cooperative. This finding provides first experimental evidence for the mechanistic importance for junctional microdomain formation. From the observation of lateral association-dissociation events of AQP0(4), we determine that the enthalpic energy gain of a single AQP0(4)-AQP0(4) interaction in the membrane plane is -2.7 k(B)T, sufficient to drive formation of microdomains. Connexon association is stronger as dynamics are rarely observed, explaining their rim localization in junctional microdomains. PMID:22796628

Colom, Adai; Casuso, Ignacio; Boudier, Thomas; Scheuring, Simon

2012-10-19

287

Septate Junctions are Required for Ommatidial Integrity and Blood-Eye Barrier Function in Drosophila  

PubMed Central

The anatomical organization of the Drosophila ommatidia is achieved by specification and contextual placement of photoreceptors, cone and pigment cells. The photoreceptors must be sealed from high ionic concentrations of the hemolymph by a barrier to allow phototransduction. In vertebrates, a blood-retinal barrier (BRB) is established by tight junctions (TJs) present in the retinal pigment epithelium and endothelial membrane of the retinal vessels. In Drosophila ommatidia, the junctional organization and barrier formation is poorly understood. Here we report that septate junctions (SJs), the vertebrate analogs of TJs, are present in the adult ommatidia and are formed between and among the cone and pigment cells. We show that the localization of Neurexin IV (Nrx IV), a SJ-specific protein, coincides with the location of SJs in the cone and pigment cells. Somatic mosaic analysis of nrx IV null mutants shows that loss of Nrx IV leads to defects in ommatidial morphology and integrity. nrx IV hypomorphic allelic combinations generated viable adults with defective SJs and displayed a compromised blood-eye barrier (BEB) function. These findings establish that SJs are essential for ommatidial integrity and in creating a BEB around the ion and light sensitive photoreceptors. Our studies may provide clues towards understanding the vertebrate BEB formation and function. PMID:18407259

Banerjee, Swati; Bainton, Roland J.; Mayer, Nasima; Beckstead, Robert; Bhat, Manzoor A.

2008-01-01

288

Realization of radial p-n junction silicon nanowire solar cell based on low-temperature and shallow phosphorus doping  

PubMed Central

A radial p-n junction solar cell based on vertically free-standing silicon nanowire (SiNW) array is realized using a novel low-temperature and shallow phosphorus doping technique. The SiNW arrays with excellent light trapping property were fabricated by metal-assisted chemical etching technique. The shallow phosphorus doping process was carried out in a hot wire chemical vapor disposition chamber with a low substrate temperature of 250°C and H2-diluted PH3 as the doping gas. Auger electron spectroscopy and Hall effect measurements prove the formation of a shallow p-n junction with P atom surface concentration of above 1020 cm?3 and a junction depth of less than 10 nm. A short circuit current density of 37.13 mA/cm2 is achieved for the radial p-n junction SiNW solar cell, which is enhanced by 7.75% compared with the axial p-n junction SiNW solar cell. The quantum efficiency spectra show that radial transport based on the shallow phosphorus doping of SiNW array improves the carrier collection property and then enhances the blue wavelength region response. The novel shallow doping technique provides great potential in the fabrication of high-efficiency SiNW solar cells. PMID:24369781

2013-01-01

289

Vezatin, an integral membrane protein of adherens junctions, is required for the sound resilience of cochlear hair cells  

PubMed Central

Loud sound exposure is a significant cause of hearing loss worldwide. We asked whether a lack of vezatin, an ubiquitous adherens junction protein, could result in noise-induced hearing loss. Conditional mutant mice bearing non-functional vezatin alleles only in the sensory cells of the inner ear (hair cells) indeed exhibited irreversible hearing loss after only one minute exposure to a 105 dB broadband sound. In addition, mutant mice spontaneously underwent late onset progressive hearing loss and vestibular dysfunction related to substantial hair cell death. We establish that vezatin is an integral membrane protein with two adjacent transmembrane domains, and cytoplasmic N- and C-terminal regions. Late recruitment of vezatin at junctions between MDCKII cells indicates that the protein does not play a role in the formation of junctions, but rather participates in their stability. Moreover, we show that vezatin directly interacts with radixin in its actin-binding conformation. Accordingly, we provide evidence that vezatin associates with actin filaments at cell–cell junctions. Our results emphasize the overlooked role of the junctions between hair cells and their supporting cells in the auditory epithelium resilience to sound trauma. PMID:20049712

Bahloul, Amel; Simmler, Marie-Christine; Michel, Vincent; Leibovici, Michel; Perfettini, Isabelle; Roux, Isabelle; Weil, Dominique; Nouaille, Sylvie; Zuo, Jian; Zadro, Cristina; Licastro, Danilo; Gasparini, Paolo; Avan, Paul; Hardelin, Jean-Pierre; Petit, Christine

2009-01-01

290

An intercellular polyamine transfer via gap junctions regulates proliferation and response to stress in epithelial cells  

PubMed Central

In the organism, quiescent epithelial cells have the potential to resume cycling as a result of various stimuli, including wound healing or oxidative stress. Because quiescent cells have a low polyamine level, resuming their growth requires an increase of their intracellular polyamine levels via de novo polyamine synthesis or their uptake from plasma. Another alternative, explored here, is an intercellular exchange with polyamine-rich cycling cells via gap junctions. We show that polyamines promote gap junction communication between proliferating cells by promoting dynamical microtubule plus ends at the cell periphery and thus allow polyamine exchange between cells. In this way, cycling cells favor regrowth in adjacent cells deprived of polyamines. In addition, intercellular interactions mediated by polyamines can coordinate the translational response to oxidative stress through the formation of stress granules. Some putative in vivo consequences of polyamine-mediated intercellular interactions are also discussed regarding cancer invasiveness and tissue regeneration. PMID:23515223

Desforges, Benedicte; Curmi, Patrick A.; Bounedjah, Ouissame; Nakib, Samir; Hamon, Loic; De Bandt, Jean-Pascal; Pastre, David

2013-01-01

291

Single P-N junction tandem photovoltaic device  

DOEpatents

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

Walukiewicz, Wladyslaw (Kensington, CA); Ager, III, Joel W. (Berkeley, CA); Yu, Kin Man (Lafayette, CA)

2012-03-06

292

Single P-N junction tandem photovoltaic device  

DOEpatents

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

Walukiewicz, Wladyslaw (Kensington, CA); Ager, III, Joel W. (Berkeley, CA); Yu, Kin Man (Lafayette, CA)

2011-10-18

293

The critical power to maintain thermally stable molecular junctions  

NASA Astrophysics Data System (ADS)

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.

Wang, Yanlei; Xu, Zhiping

2014-07-01

294

Design of mode-sorting asymmetric Y-junctions.  

PubMed

The theory of mode-sorting in bimodal asymmetric Y-junctions is extended to multimode asymmetric Y-junctions with multiple output arms. This theory allows for the optimization of these mode-sorting planar structures. Asymmetric Y-junctions provide unique opportunities for spatial mode division multiplexing (MDM) of optical fiber. Spatial MDM is considered paramount to overcoming the bandwidth limitations of single-mode fiber. The design criteria presented in this paper facilitate their design. PMID:22614579

Riesen, Nicolas; Love, John D

2012-05-20

295

Cardiovascular Gap Junction Proteins: Molecular Characterization and Biochemical Regulation  

Microsoft Academic Search

\\u000a Gap junctions are plasma membrane specializations containing channels which permit the intercellular exchange of ions and\\u000a small molecules. Gap junction channels are of central importance in electrically excitable tissues such as myocardium where\\u000a cell-to-cell passage of ions allows propagation of action potentials. Gap junctions are also present in many non-excitable\\u000a cells (for example endothelial cells) where they may facilitate intercellular

Eric C. Beyer; Kyung Hwan Seul; David M. Larson

296

Frequency conversion and computation with PN junction devices  

Microsoft Academic Search

The usual assumptions of PN junction theory have been applied to frequency conversion. The matrix describing superheterodyne operation can be expressed in terms of the small-signal diffusion admittances and a matrix depending on the local-oscillator voltage. The analysis also gives the large-signal admittances of a PN junction. A sufficiently small bonded contact and the emitter junction of a high-frequency transistor

1955-01-01

297

Diacylglycerol downregulates junctional membrane permeability. TMB-8 blocks this effect  

Microsoft Academic Search

Summary We tested the question whether junctional cell-to-cell communication is regulated by the diacylglycerol branch of the phosphoinositide transmembrane signal pathway. Cultured epithelial rat liver cells were treated with the synthetic diacylglycerol 1-oleoyl-2-acetyl glycerol, while their junctional permeability was probed with the microinjected 443-dalton fluorescent tracer Lucifer Yellow. The treatment reduced junctional permeability (without affecting Lucifer permeability of nonjunctional cell

Toshihiko Yada; Birgit Rose; Werner R. Loewenstein

1985-01-01

298

Definitive Evidence for the existence of tight junctions in invertebrates  

PubMed Central

Extensive and unequivocal tight junctions are here reported between the lateral borders of the cellular layer that circumscribes the arachnid (spider) central nervous system. This account details the features of these structures, which form a beltlike reticulum that is more complex than the simple linear tight junctions hitherto found in invertebrate tissues and which bear many of the characteristics of vertebrate zonulae occludentes. We also provide evidence that these junctions form the basis of a permeability barrier to exogenous compounds. In thin sections, the tight junctions are identifiable as punctate points of membrane apposition; they are seen to exclude the stain and appear as election- lucent moniliform strands along the lines of membrane fusion in en face views of uranyl-calcium-treated tissues. In freeze-fracture replicas, the regions of close membrane apposition exhibit P-face (PF) ridges and complementary E-face (EF) furrows that are coincident across face transitions, although slightly offset with respect to one another. The free inward diffusion of both ionic and colloidal lanthanum is inhibited by these punctate tight junctions so that they appear to form the basis of a circumferential blood-brain barrier. These results support the contention that tight junctions exist in the tissues of the invertebrata in spite of earlier suggestions that (a) they are unique to vertebrates and (b) septate junctions are the equivalent invertebrate occluding structure. The component tight junctional 8- to 10-nm-particulate PF ridges are intimately intercalated with, but clearly distinct from, inverted gap junctions possessing the 13-nm EF particles typical of arthropods. Hence, no confusion can occur as to which particles belong to each of the two junctional types, as commonly happens with vertebrate tissues, especially in the analysis of developing junctions. Indeed, their coexistance in this way supports the idea, over which there has been some controversy, that the intramembrane particles making up these two junctional types must be quite distinct entities rather than products of a common precursor. PMID:7410478

Lane, NJ; Chandler, HJ

1980-01-01

299

Origin and evolution of exon\\/intron junctions  

Microsoft Academic Search

In nuclear mRNA genes, exon\\/intron junctions (both exon\\/intron and intron\\/exon junctions in this paper) possess the specific duplex pattern with the corresponding ends (3' to 3', 5' to 5') of exons and introns more or less identical. In genes with group I or group II introns, overall analyses indicate there are also related patterns in their exon\\/intron junctions. From the

SHANG-HONG ZHANG

1998-01-01

300

Molecular Conductance of oligophenylene-vinylene in Metallic Break Junctions  

Microsoft Academic Search

Break junctions between a metallic tip and a metallic substrate have proven to be extremely useful tools for characterizing single-molecule electrical conductance. Conductance measurements while repeatedly breaking and reforming junctions are conducive to rapid statistical characterization. We will present preliminary results of room temperature break junction conductance measurements on amine-terminated oligophenylene-vinylene (OPV) oligomers. Recent low temperature measurements of OPV oligomers

Patrick Wheeler; Meng Lu; David Corley; James Tour; Doug Natelson

2008-01-01

301

Structure and function of gap junctions in the developing brain  

Microsoft Academic Search

Gap-junction-dependent neuronal communication is widespread in the developing brain, and the prevalence of gap-junctional coupling is well correlated with specific developmental events. We summarize here our current knowledge of the contribution of gap junctions to brain development and propose that they carry out this role by taking advantage of the full complement of their functional properties. Thus, hemichannel activation may

Roberto Bruzzone; Rolf Dermietzel

2006-01-01

302

Reciprocal myocardial-endocardial interactions pattern the delay in atrioventricular junction conduction.  

PubMed

Efficient blood flow depends on two developmental processes that occur within the atrioventricular junction (AVJ) of the heart: conduction delay, which entrains sequential chamber contraction; and valve formation, which prevents retrograde fluid movement. Defects in either result in severe congenital heart disease; however, little is known about the interplay between these two crucial developmental processes. Here, we show that AVJ conduction delay is locally assigned by the morphogenetic events that initiate valve formation. Our data demonstrate that physical separation from endocardial-derived factors prevents AVJ myocardium from becoming fast conducting. Mechanistically, this physical separation is induced by myocardial-derived factors that support cardiac jelly deposition at the onset of valve formation. These data offer a novel paradigm for conduction patterning, whereby reciprocal myocardial-endocardial interactions coordinate the processes of valve formation with establishment of conduction delay. This, in turn, synchronizes the electrophysiological and structural events necessary for the optimization of blood flow through the developing heart. PMID:25273084

Bressan, Michael; Yang, PoAn Brian; Louie, Jonathan D; Navetta, Alicia M; Garriock, Robert J; Mikawa, Takashi

2014-11-01

303

Microfluidics Formation of Bubbles in a Multisection Flow-Focusing  

E-print Network

Microfluidics Formation of Bubbles in a Multisection Flow-Focusing Junction Michinao Hashimoto the stable formation of trains of mono-, bi-, and tri-disperse bubbles in microfluidic flow- focusing (FF-assembly through the patterns of flow created by the bubbles. 1.1 Bubbles and Droplets in Microfluidics

Prentiss, Mara

304

PKC? PHOSPHORYLATES OCCLUDIN AND PROMOTES ASSEMBLY OF EPITHELIAL TIGHT JUNCTIONS  

PubMed Central

SYNOPSIS Evidence indicates that protein kinases play an important role in the regulation of epithelial tight junctions. In the present study, we investigated the role of PKC? in tight junction regulation in Caco-2 and MDCK cell monolayers. Inhibition of PKC? by a specific PKC?-pseudosubstrate peptide results in redistribution of occludin and ZO-1 from the intercellular junctions and disruption of barrier function without affecting cell viability. Reduced expression of PKC? by antisense oligonucleotide or shRNA also results in compromised tight junction integrity. Inhibition or knock down of PKC? delays calcium-induced assembly of tight junctions. Tight junction disruption by PKC?-pseudosubstrate is associated with the dephosphorylation of occludin and ZO-1 on Ser and Thr residues. PKC? directly binds to the C-terminal domain of occludin and phosphorylates it on Thr residues. T403, T404, T424 and T438 in occludin C-terminal domain are the predominant sites of PKC?-dependent phosphorylation. T424A or T438A mutation in full length occludin delays its assembly into the tight junctions. Inhibition of PKC? also induces redistribution of occludin and ZO-1 from the tight junctions and dissociates these proteins from the detergent-insoluble fractions in mouse ileum. This study demonstrates that PKC? phosphorylates occludin on specific Thr residues and promotes assembly of epithelial tight junctions. PMID:21545357

Jain, Suneet; Suzuki, Takuya; Seth, Ankur; Samak, Geetha; Rao, RadhaKrishna

2012-01-01

305

Flow mechanotransduction regulates traction forces, intercellular forces, and adherens junctions  

PubMed Central

Endothelial cells respond to fluid shear stress through mechanotransduction responses that affect their cytoskeleton and cell-cell contacts. Here, endothelial cells were grown as monolayers on arrays of microposts and exposed to laminar or disturbed flow to examine the relationship among traction forces, intercellular forces, and cell-cell junctions. Cells under laminar flow had traction forces that were higher than those under static conditions, whereas cells under disturbed flow had lower traction forces. The response in adhesion junction assembly matched closely with changes in traction forces since adherens junctions were larger in size for laminar flow and smaller for disturbed flow. Treating the cells with calyculin-A to increase myosin phosphorylation and traction forces caused an increase in adherens junction size, whereas Y-27362 cause a decrease in their size. Since tugging forces across cell-cell junctions can promote junctional assembly, we developed a novel approach to measure intercellular forces and found that these forces were higher for laminar flow than for static or disturbed flow. The size of adherens junctions and tight junctions matched closely with intercellular forces for these flow conditions. These results indicate that laminar flow can increase cytoskeletal tension while disturbed flow decreases cytoskeletal tension. Consequently, we found that changes in cytoskeletal tension in response to shear flow conditions can affect intercellular tension, which in turn regulates the assembly of cell-cell junctions. PMID:22447948

Ting, Lucas H.; Jahn, Jessica R.; Jung, Joon I.; Shuman, Benjamin R.; Feghhi, Shirin; Han, Sangyoon J.; Rodriguez, Marita L.

2012-01-01

306

The 'depletion layer' of amorphous p-n junctions  

NASA Technical Reports Server (NTRS)

It is shown that within reasonable approximations for the density of state distribution within the mobility gap of a:Si, a one-to-one correspondence exists between the electric field distribution in the transition region of an amorphous p-n junction and that in the depletion layer of a crystalline p-n junction. Thus it is inferred that the depletion layer approximation which leads to a parabolic potential distribution within the depletion layer of crystalline junctions also constitutes a fair approximation in the case of amorphous junctions. This fact greatly simplifies an analysis of solid-state electronic devices based on amorphous material (i.e., solar cells).

Von Roos, O.

1981-01-01

307

Magic-T Junction using Microstrip/Slotline Transitions  

NASA Technical Reports Server (NTRS)

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 among all four ports, and to strong parasitic couplings at the microstrip/slotline T junction, where four microstrip lines and a slotline are combined. The present improved broadband magic-T junction (see figure) includes a microstrip ring structure and two microstrip- to-slotline transitions. One of the microstrip/slotline transitions is a small T junction between the ring and a slotline; the other microstrip/slotline transition effects coupling between the slotline and port E. The smallness of the T junction and the use of minimum-size slotline terminations help to minimize radiation loss. An impedance-transformation network that includes multiple quarter-wavelength sections is used to increase the operating bandwidth and minimize the parasitic coupling around the microstrip/slotline T junction. As a result, the improved junction has greater bandwidth and lower phase imbalance at the sum and difference ports than did the prior junction.

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

2008-01-01

308

Photoresponse in arrays of thermoelectric nanowire junctions  

NASA Astrophysics Data System (ADS)

We report the first demonstration of optical detection by thermoelectric nanowire junctions. We employed devices composed of bismuth nanowire arrays which are capped with a transparent indium tin oxide electrode. The incident surface features very low optical reflectivity and enhanced light trapping. The unique attributes of the thermoelectric arrays are the combination of strong temporal and optical wavelength dependences of the photocurrent. Under infrared illumination, the signal can be completely described by thermoelectric effects considering cooling rates given by heat diffusion through the array. In addition, under visible illumination, we observe a photovoltaic response.

Huber, T. E.; Scott, R.; Johnson, S.; Brower, T.; Belk, J. H.; Hunt, J. H.

2013-07-01

309

Thermal conductance through a nanoscale junction  

NASA Astrophysics Data System (ADS)

We calculate the thermal transport between two macroscopic dielectrics held at different temperatures and connected in a point-contact geometry. In the low-temperature regime, where the phonon transmission probability through the junction is small, the thermal current is found to depend on a product of the local vibrational spectral densities of the two bodies, as in the weak-link geometry [K. R. Patton and M. R. Geller, Phys. Rev. B 64, 155320 (2001)]. These results suggest the possibility of a scanning thermal-conductance microscope, a thermal analog of the STM, that measures the local vibrational density of states of a system with atomic-scale resolution.

Chang, Chun-Min; Geller, Michael

2004-03-01

310

Readout for phase qubits without Josephson junctions  

NASA Astrophysics Data System (ADS)

We present a readout scheme for phase qubits which eliminates the read-out superconducting quantum interference device so that the entire qubit and measurement circuitry only require a single Josephson junction. Our scheme capacitively couples the phase qubit directly to a transmission line and detects its state after the measurement pulse by determining a frequency shift observable in the forward scattering parameter of the readout microwaves. This readout is extendable to multiple phase qubits coupled to a common readout line and can in principle be used for other flux biased qubits having two quasistable readout configurations.

Steffen, Matthias; Kumar, Shwetank; DiVincenzo, David; Keefe, George; Ketchen, Mark; Rothwell, Mary Beth; Rozen, Jim

2010-03-01

311

Junctional angle of a bihanded helix  

NASA Astrophysics Data System (ADS)

Helical filaments having sections of reversed chirality are common phenomena in the biological realm. The apparent angle between the two sections of opposite handedness provides information about the geometry and elasticity of the junctional region. In this paper, the governing differential equations for the local helical axis are developed, and asymptotic solutions of the governing equations are solved by perturbation theory. The asymptotic solutions are compared with the corresponding numerical solutions, and the relative error at second order is found to be less than 1.5% over a range of biologically relevant curvature and torsion values from 0 to 1/2 in dimensionless units.

Yang, Jing; Wolgemuth, Charles W.; Huber, Greg

2014-10-01

312

Phonon interference effects in molecular junctions  

SciTech Connect

We study coherent phonon transport through organic, ?-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.

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)] [Center for Atomic-scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

2013-12-28

313

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

ERIC Educational Resources Information Center

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…

Quinn, David W.; Quinn, Nancy W.

314

Junction current distributions and ac impedances of thin resistive films on semiconductor junctions  

Microsoft Academic Search

Certain aspects of the blocking layer behavior in semiconductor heterojunction lasers can be modeled as a thin resistive film overlaying a semiconductor forward biased junction. The dc behavior of such a model has been studied previously by W. B. Joyce and S. H. Wemple [J. Appl. Phys. 41, 3818 (1970)]. This paper studies the ac aspects of that model, and

G. A. Baraff

1995-01-01

315

Low resistance junctions in crayfish. Structural changes with functional uncoupling  

PubMed Central

Electrical uncoupling of crayfish septate lateral giant axons is paralleled by structural changes in the gap junctions. The changes are characterized by a tighter aggregation of the intramembrane particles and a decrease in the overall width of the junction and the thickness of the gap. Preliminary measurements indicate also a decrease in particle diameter. The uncoupling is produced by in vitro treatment of crayfish abdominal cords either with a Ca++, Mg++-free solution containing EDTA, followed by return to normal saline (Van Harreveld's solution), or with VAn Harreveld's solution containing dinitrophenol (DNP). The uncoupling is monitored by the intracellular recording of the electrical resistance at a septum between lateral giant axons. The junctions of the same septum are examined in thin sections; those of other ganglia of the same chain used for the electrical measurements are studied by freeze-fracture. In controls, most junctions contain a more or less regular array of particles repeating at a center to center distance of approximately 200 A. The overall width of the junctions is approximately 200 A and the gap thickness is 40-50 A. Vesicles (400-700 A in diameter) are closely apposed to the junctional membranes. In uncoupled axons, most junctions contain a hexagonal array of particles repeating at a center to center distance of 150-155 A. The overall width of the junctions is approximately 180 A and the gap thickness is 20-30 A. These junctions are usually curved and are rarely associated with vesicles. Isolated, PTA-stained junctions, also believed to be uncoupled, display similar structural features. There are reasons to believe that the changes in structure and permeability are triggered by an increase in the intracellular free Ca++ concentration. Most likely, the changes in permeability are caused by conformational changes in some components of the intramembrane particles at the gap junctions. PMID:820701

1976-01-01

316

Switching and Rectification in Carbon-Nanotube Junctions  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

317

Enterocytes' tight junctions: From molecules to diseases  

PubMed Central

Tight junctions (TJs) are structures between cells where cells appear in the closest possible contact. They are responsible for sealing compartments when epithelial sheets are generated. They regulate the permeability of ions, (macro) molecules and cells via the paracellular pathway. Their structure at the electron microscopic level has been well known since the 1970s; however, only recently has their macromolecular composition been revealed. This review first examines the major macromolecular components of the TJs (occludin, claudins, junctional adhesion molecule and tricellulin) and then the associated macromolecules at the intracellular plaque [zonula occludens (ZO)-1, ZO-2, ZO-3, AF-6, cingulin, 7H6]. Emphasis is given to their interactions in order to begin to understand the mode of assembly of TJs. The functional significance of TJs is detailed and several mechanisms and factors involved are discussed briefly. Emphasis is given to the role of intestinal TJs and the alterations observed or speculated in diverse disease states. Specifically, intestinal TJs may exert a pathogenetic role in intestinal (inflammatory bowel disease, celiac disease) and extraintestinal diseases (diabetes type 1, food allergies, autoimmune diseases). Additionally, intestinal TJs may be secondarily disrupted during the course of diverse diseases, subsequently allowing the bacterial translocation phenomenon and promoting the systemic inflammatory response, which is often associated with clinical deterioration. The major questions in the field are highlighted. PMID:22184542

Assimakopoulos, Stelios F; Papageorgiou, Ismini; Charonis, Aristidis

2011-01-01

318

Switching of Current in a Molecular Junction  

NASA Astrophysics Data System (ADS)

Achieving atomic level control at the metal-molecule interface in a single molecule conductance measurement is a difficult task that hinders the progress in molecular electronics. The lack of atomic level structural information of the interface makes the theoretical interpretation of experimental data much harder. Herein, we create an ensemble of device structure by varying metal-molecule binding sites, the orientation of the molecule at the interface, interface distance, and conformational change within the molecule to study junction dependent conductance behavior in Ruthenium-Bis(terpyridine) molecular wire, which has been fabricated and characterized. An orbital dependent DFT in conjunction with a parameter free, single particle Green's function approach is used to study the I-V characteristics. Our calculation for the weakly-coupled ONTOP junction geometry yields a relatively small (OFF state) current value below a threshold voltage (Vth). The current value is found to increase at Vth and remains flat (ON state) after the threshold value. A similar non-linear I-V curve with a current switching behavior has been reported experimentally.

Dhungana, Kamal; Mandal, Subhasish; Pati, Ranjit

2013-03-01

319

76 FR 56966 - Amendment of Class D and Modification of Class E Airspace; Grand Junction, CO  

Federal Register 2010, 2011, 2012, 2013

...E airspace to update the airport name from Grand Junction, Walker Field. DATES: Effective date, 0901 UTC, December 15, 2011...E airspace to update the airport name from Grand Junction, Walker Field, to Grand Junction Regional Airport, Grand...

2011-09-15

320

77 FR 38705 - Draft Specification for Airport Light Bases, Transformer Housings, Junction Boxes, and...  

Federal Register 2010, 2011, 2012, 2013

...Administration Draft Specification for Airport Light Bases, Transformer Housings, Junction Boxes...Draft ``Specification for Airport Light Bases, Transformer Housings, Junction Boxes...standards and recommendations for airport light bases, transformer housings, junction...

2012-06-28

321

The cell-cell junctions of mammalian testes: I. The adhering junctions of the seminiferous epithelium represent special differentiation structures.  

PubMed

The seminiferous tubules and the excurrent ducts of the mammalian testis are physiologically separated from the mesenchymal tissues and the blood and lymph system by a special structural barrier to paracellular translocations of molecules and particles: the "blood-testis barrier", formed by junctions connecting Sertoli cells with each other and with spermatogonial cells. In combined biochemical as well as light and electron microscopical studies we systematically determine the molecules located in the adhering junctions of adult mammalian (human, bovine, porcine, murine, i.e., rat and mouse) testis. We show that the seminiferous epithelium does not contain desmosomes, or "desmosome-like" junctions, nor any of the desmosome-specific marker molecules and that the adhering junctions of tubules and ductules are fundamentally different. While the ductules contain classical epithelial cell layers with E-cadherin-based adherens junctions (AJs) and typical desmosomes, the Sertoli cells of the tubules lack desmosomes and "desmosome-like" junctions but are connected by morphologically different forms of AJs. These junctions are based on N-cadherin anchored in cytoplasmic plaques, which in some subforms appear thick and dense but in other subforms contain only scarce and loosely arranged plaque structures formed by ?- and ?-catenin, proteins p120, p0071 and plakoglobin, together with a member of the striatin family and also, in rodents, the proteins ZO-1 and myozap. These N-cadherin-based AJs also include two novel types of junctions: the "areae adhaerentes", i.e., variously-sized, often very large cell-cell contacts and small sieve-plate-like AJs perforated by cytoplasm-to-cytoplasm channels of 5-7 nm internal diameter ("cribelliform junctions"). We emphasize the unique character of this epithelium that totally lacks major epithelial marker molecules and structures such as keratin filaments and desmosomal elements as well as EpCAM- and PERP-containing junctions. We also discuss the nature, development and possible functions of these junctions. PMID:24907851

Domke, Lisa M; Rickelt, Steffen; Dörflinger, Yvette; Kuhn, Caecilia; Winter-Simanowski, Stefanie; Zimbelmann, Ralf; Rosin-Arbesfeld, Rina; Heid, Hans; Franke, Werner W

2014-09-01

322

Gap junctions in the rat cochlea: immunohistochemical and ultrastructural analysis  

Microsoft Academic Search

Gap junctions in the rat cochlea were investigated using immunostaining for connexin26 and transmission electron microscopy. Electron microscopy of normal and pre-embedded immunostained material showed that there were gap junctions between and among all cells that light microscopy showed to have immunostained appositions. Light microscopy showed immunostaining between and among all cell types that electron microscopy showed to be joined

Toshihiko Kikuchi; Robert S. Kimura; David L. Paul; Joe C. Adams

1995-01-01

323

Diencephalic-Mesencephalic Junction Dysplasia: A Novel Recessive Brain Malformation  

ERIC Educational Resources Information Center

We describe six cases from three unrelated consanguineous Egyptian families with a novel characteristic brain malformation at the level of the diencephalic-mesencephalic junction. Brain magnetic resonance imaging demonstrated a dysplasia of the diencephalic-mesencephalic junction with a characteristic "butterfly"-like contour of the midbrain on…

Zaki, Maha S.; Saleem, Sahar N.; Dobyns, William B.; Barkovich, A. James; Bartsch, Hauke; Dale, Anders M.; Ashtari, Manzar; Akizu, Naiara; Gleeson, Joseph G.; Grijalvo-Perez, Ana Maria

2012-01-01

324

Internal Pulse Amplification in High Field, Silicon Radiation Detection Junctions  

Microsoft Academic Search

Significant internal pulse amplification has been observed in silicon p-n junction radiation detectors operated in the very high field (but prebreakdown) region. Such internal electric field values (peak fields of 60 - 250 kilovolts cm-1) are attainable over distances of up to 250 microns through the use of geometrical control of the field existing at the surface of the junction.

Gerald C. Huth; James B. Trice; James A. Shannon; Russell A. McKinney

1965-01-01

325

Josephson junctions in high-T/sub c/ superconductors  

DOEpatents

The invention includes a high T/sub c/ Josephson sperconducting junction as well as the method and apparatus which provides the junction by application of a closely controlled and monitored electrical discharge to a microbridge region connecting two portions of a superconducting film.

Falco, C.M.; Lee, T.W.

1981-01-14

326

THE USE OF SUPERCONDUCTING JUNCTIONS IN MAGNETOMETRY By J. CLARKE,  

E-print Network

of radius R and inductance L. A super- conducting galvanometer of negligible inductance is mounted to the radius of the ring. Thus the magnetometer may be made arbitrarily sensitive to a uniform magnetic field] junctions in parallel. A Josephson junction consists of two superconductors separated by an insulating

Boyer, Edmond

327

Oocyte triplet pairing for electrophysiological investigation of gap junctional coupling  

Microsoft Academic Search

Gap junctions formed by expressing connexin subunits in Xenopus oocytes provide a valuable tool for revealing the gating properties of intercellular gap junctions in electrically coupled cells. We describe a new method that consists of simultaneous triple recordings from 3 apposed oocytes expressing exogenous connexins. The advantages of this method are that in one single experiment, 1 oocyte serves as

Abdallah Hayar; Amanda Charlesworth; Edgar Garcia-Rill

2010-01-01

328

Gap junctions in olfactory neurons modulate olfactory sensitivity  

Microsoft Academic Search

BACKGROUND: One of the fundamental questions in olfaction is whether olfactory receptor neurons (ORNs) behave as independent entities within the olfactory epithelium. On the basis that mature ORNs express multiple connexins, I postulated that gap junctional communication modulates olfactory responses in the periphery and that disruption of gap junctions in ORNs reduces olfactory sensitivity. The data collected from characterizing connexin

Chunbo Zhang

2010-01-01

329

A new compact model for junctions in advanced CMOS technologies  

Microsoft Academic Search

We present a new compact model for the junction capacitances and leakage currents in deep-submicron CMOS technologies. The model contains Shockley-Read-Hall generation\\/recombination, trap-assisted tunneling, band-to-band-tunneling, and avalanche breakdown. It has been validated for a wide range of bias and temperature, for NMOS and PMOS junctions, and for different CMOS generations

A. J. Scholten; G. D. J. Smit; M. Durand; R. van Langevelde; C. J. J. Dachs; D. B. M. Klaassen

2005-01-01

330

DC flux parametron: A new approach to Josephson junction logic  

Microsoft Academic Search

The direct current flux parametron using Josephson junction and based on the principle of parametron seems to be the answer for the search of new technology for the future needs of computer power. The combination of its very high switching speed and highly integrable Josephson junction with the established parametron computer technology accounts for its high performance. This book presents

K. F. Loe; E. Goto

1986-01-01

331

Processing of Superconductor-Normal-Superconductor Josephson Edge Junctions  

NASA Technical Reports Server (NTRS)

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.

Kleinsasser, A. W.; Barner, J. B.

1997-01-01

332

Capacitively coupled Josephson junctions: A two-qubit system  

Microsoft Academic Search

We describe how single Josephson junctions can be connected together capacitively to form a two-qubit system. We discuss the general behavior of this system show the energy level dependence on various junction parameters and choice of coupling strengths. We also discuss measurement techniques for reading out both qubits which are relevant to our ongoing experiments.

R. C. Ramos; F. W. Strauch; P. R. Johnson; A. J. Berkley; H. Xu; M. A. Gubrud; J. R. Anderson; C. J. Lobb; A. J. Dragt; F. C. Wellstood

2003-01-01

333

Duodeno-jejunal junction dyssynergia: Description of a novel syndrome  

PubMed Central

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. PMID:17696232

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

2007-01-01

334

TEMPORAL CHANGE IN GAP JUNCTION FUNCTION IN PRIMARY HEPATOCYTES  

EPA Science Inventory

TEMPORAL CHANGES IN GAP JUNCTION FUNCTION IN PRIMARY * The objective of this study was to examine the reduction in gap junction communication (GJC) in primary hepatocytes due to coincident melatonin and magnetic field treatments to determine if these conditions could prov...

335

Progress in understanding the physics of HTS Josephson junctions  

Microsoft Academic Search

The experimental results obtained in high-Tc Josephson junctions are reviewed with the emphasis on intrinsic Josephson effect and long-range proximity effect junctions (LRPJ). The possibility of the experimental observation of the intrinsic Josephson effect is discussed. A theoretical model based on resonant tunneling via localized states is proposed for the description of normal and supercurrent flow in LRPJ.

M. Yu. Kupriyanov; J. S. Tsai

1995-01-01

336

Profiling the Thermoelectric Power of Semiconductor Junctions with  

E-print Network

Profiling the Thermoelectric Power of Semiconductor Junctions with Nanometer Resolution Ho-Ki Lyeo,3 * We have probed the local thermoelectric power of semiconductor nanostruc- tures with the use of ultrahigh-vacuum scanning thermoelectric microscopy. When applied to a p-n junction, this method reveals

337

Aberrant chromosome morphology in human cells defective for Holliday junction resolution  

PubMed Central

In somatic cells, Holliday junctions can be formed between sister chromatids during the recombinational repair of DNA breaks or after replication fork demise. A variety of processes act upon Holliday junctions to remove them from DNA, in events that are critical for proper chromosome segregation. In human cells, the BLM protein, inactivated in individuals with Bloom’s syndrome, acts in combination with topoisomerase III?, RMI1 and RMI2 (BTR complex) to promote the dissolution of double Holliday junctions1,2. Cells defective for BLM exhibit elevated levels of sister chromatid exchanges (SCEs) and patients with Bloom’s syndrome develop a broad spectrum of early-onset cancers caused by chromosome instability3. MUS81–EME1 (refs 4-7), SLX1–SLX4 (refs 8-11) and GEN1 (refs 12, 13) also process Holliday junctions but, in contrast to the BTR complex, do so by endonucleolytic cleavage. Here we deplete these nucleases from Bloom’s syndrome cells to analyse human cells compromised for the known Holliday junction dissolution/resolution pathways. We show that depletion of MUS81 and GEN1, or SLX4 and GEN1, from Bloom’s syndrome cells results in severe chromosome abnormalities, such that sister chromatids remain interlinked in a side-by-side arrangement and the chromosomes are elongated and segmented. Our results indicate that normally replicating human cells require Holliday junction processing activities to prevent sister chromatid entanglements and thereby ensure accurate chromosome condensation. This phenotype was not apparent when both MUS81 and SLX4 were depleted from Bloom’s syndrome cells, suggesting that GEN1 can compensate for their absence. Additionally, we show that depletion of MUS81 or SLX4 reduces the high frequency of SCEs in Bloom’s syndrome cells, indicating that MUS81 and SLX4 promote SCE formation, in events that may ultimately drive the chromosome instabilities that underpin early-onset cancers associated with Bloom’s syndrome. PMID:21399624

Wechsler, Thomas; Newman, Scott; West, Stephen C.

2013-01-01

338

Endocytosis of cadherin from intracellular junctions is the driving force for cadherin adhesive dimer disassembly.  

PubMed

The adhesion receptor E-cadherin maintains cell-cell junctions by continuously forming short-lived adhesive dimers. Here mixed culture cross-linking and coimmunoprecipitation assays were used to determine the dynamics of adhesive dimer assembly. We showed that the amount of these dimers increased dramatically minutes after the inhibition of endocytosis by ATP depletion or by hypertonic sucrose. This increase was accompanied by the efficient recruitment of E-cadherin into adherens junctions. After 10 min, when the adhesive dimer amount had reached a plateau, the assembly of new dimers stalled completely. These cells, in a striking difference from the control, became unable to disintegrate both their intercellular contacts and adhesive dimers in response to calcium depletion. The same effects, but after a slightly longer time course, were obtained using acidic media, another potent approach inhibiting endocytosis. These data suggest that endocytosis is the main pathway for the dissociation of E-cadherin adhesive dimers. Its inhibition blocks the replenishment of the monomeric cadherin pool, thereby inhibiting new dimer formation. This suggestion has been corroborated by immunoelectron microscopy, which revealed cadherin-enriched coated pit-like structures in close association with adherens junctions. PMID:16760429

Troyanovsky, Regina B; Sokolov, Eugene P; Troyanovsky, Sergey M

2006-08-01

339

National Uranium Resource Evaluation. Bibliographic index of Grand Junction office uranium reports  

SciTech Connect

In October 1978, Mesa College entered into subcontract with Bendix Field Engineering Corporation (BFEC) to prepare a bibliographic index of the uranium raw materials reports issued by the Grand Junction Office of the US Department of Energy (DOE). Bendix, prime contractor to the Grand Junction Office, operates the Technical Library at the DOE facility. Since the early 1950s, approximately 2700 reports have been issued by the Grand Junction Office. These reports were the results of uranium investigations conducted by federal agencies and their subcontractors. The majority of the reports cover geology, mineralogy, and metallurgy of uranium and/or thorium. No single, complete list of these reports existed. The purpose of this subcontract was to compile a comprehensive index to these reports. The Mesa College geology faculty worked with the BFEC and DOE staffs to develop the format for the index. Undergraduate geology students from Mesa compiled a master record sheet for each report. All reports issued up to January 1, 1979 were included in the bibliography. The bibliography is in preliminary, unedited form. It is being open-filed at this time, on microfiche, to make the information available to the public on a timely basis. The bibliography is divided into a master record list arranged in alpha-numeric order by report identification number, with separate indices arranged by title, author, state and county, 1/sup 0/ x 2/sup 0/ NTMS quadrangle, key words, and exploration area.

Johnson, J.B.

1981-05-01

340

Cx30.2 can form heteromeric gap junction channels with other cardiac connexins  

PubMed Central

Since most cells in the heart co-express multiple connexins, we studied the possible heteromeric interactions between connexin30.2 and connexin40, connexin43 or connexin45 in transfected cells. Double label immunofluorescence microscopy showed that connexin30.2 extensively co-localized with each co-expressed connexin at appositional membranes. When Triton X-100 solubilized connexons were affinity purified from co-expressing cells, connexin30.2 was isolated together with connexin40, connexin43, or connexin45. Co-expression of connexin30.2 with connexin40, connexin43, or connexin45 did not significantly reduce total junctional conductance. Gap junction channels in cells co-expressing connexin30.2 with connexin43 or connexin45 exhibited voltage-dependent gating intermediate between that of either connexin alone. In contrast, connexin30.2 dominated the voltage dependence when co-expressed with connexin40. Our data suggest that connexin30.2 can form heteromers with the other cardiac connexins and that mixed channel formation will influence the gating properties of gap junctions in cardiac regions that co-express these connexins. PMID:18291099

Gemel, Joanna; Lin, Xianming; Collins, Raymond; Veenstra, Richard D.; Beyer, Eric C.

2008-01-01

341

Ve-ptp Modulates Vascular Integrity by Promoting Adherens Junction Maturation  

PubMed Central

Background Endothelial cell junctions control blood vessel permeability. Altered permeability can be associated with vascular fragility that leads to vessel weakness and haemorrhage formation. In vivo studies on the function of genes involved in the maintenance of vascular integrity are essential to better understand the molecular basis of diseases linked to permeability defects. Ve-ptp (Vascular Endothelial-Protein Tyrosine Phosphatase) is a transmembrane protein present at endothelial adherens junctions (AJs). Methodology/Principal Findings We investigated the role of Ve-ptp in AJ maturation/stability and in the modulation of endothelial permeability using zebrafish (Danio rerio). Whole-mount in situ hybridizations revealed zve-ptp expression exclusively in the developing vascular system. Generation of altered zve-ptp transcripts, induced separately by two different splicing morpholinos, resulted in permeability defects closely linked to vascular wall fragility. The ultrastructural analysis revealed a statistically significant reduction of junction complexes and the presence of immature AJs in zve-ptp morphants but not in control embryos. Conclusions/Significance Here we show the first in vivo evidence of a potentially critical role played by Ve-ptp in AJ maturation, an important event for permeability modulation and for the development of a functional vascular system. PMID:23251467

Carra, Silvia; Foglia, Efrem; Cermenati, Solei; Bresciani, Erica; Giampietro, Costanza; Lora Lamia, Carla; Dejana, Elisabetta

2012-01-01

342

A morphological and functional study of the cavo-hepatic junction in the human.  

PubMed

The authors studied the morphological and structural aspects of the junctions between the hepatic veins and the inferior vena cava. The study was carried out on 20 specimens obtained from adult cadavers of both sexes, fixed in 10% formaldehyde solution. The hepatic veins with their junctions on the inferior vena cava were isolated. Then a macroscopic analysis of the openings of the hepatic veins into the inferior vena cava was performed. Part of this material was embedded in paraffin, submitted to serial sectioning and stained with Azan's trichrome and resorcin-fuchsin. Three hepatic veins were observed in all cases: right, left and the middle. In 20% of the cases the middle hepatic vein opens directly into the inferior vena cava. The hepatic vein openings are supported by two pillars inferiorly united through a semilunar fold. The hepatic vein wall is greatly thickened at the level of its junction with the inferior vena cava, showing a large amount of muscular and collagenous fibers. These bundles constitute a sphincter-like formation which may play a physiological role in the control of the hepatic circulation. PMID:8896149

Cavalcanti, J S; Andrade, L P; Moreira, I E; Rietra, P H; Oliveira, M L

1995-01-01

343

Morphological observation of Y and T junctions in nanostructured boron nitride thin films.  

PubMed

Formations of Y and T nano junctions have been observed in boron nitride films deposited on silicon substrates by plasma chemical reaction of diborane (B2H6 diluted in hydrogen) and ammonia (NH3) gases using dual frequency (microwave/radio) plasma enhanced chemical vapor deposition technique without any intentional heating of the substrates. It has been observed that these nano junctions form at a critical feed gas ratio of ammonia and diborane. We have investigated the effect of gas feed ratio R (=NH3/B2H6) in the plasma reaction chamber, keeping all other deposition parameters constant, on the morphology of boron nitride films. The deposited films are characterized by SEM, AFM, TEM and Laser Raman. For gas feed ratio, R < 100, octahedron and cubic morphologies have been observed in BN films and on increasing R to >100, size of the crystallites reduces to nanometer level. In some of our BN samples deposited at a critical value of gas ratio (R = 400), uniform Y and T junctions having bamboo like morphologies, in nanometer level, have been observed, which we wish to emphasis here as an interesting and newer observation in boron nitride films deposited by the dual frequency PECVD technique. This change in morphology exhibited by varying gas feed ratio is mainly due to excess nitrogen ions in the plasma. PMID:19051906

Kumar, Sushil; Parashar, A; Rauthan, C M S; Singhal, S K; Dixit, P N; Singh, B P; Bhattacharyya, R

2008-07-01

344

Neural differentiation, NCAM-mediated adhesion, and gap junctional communication in neuroectoderm. A study in vitro  

PubMed Central

We studied the development of NCAM and gap junctional communication, and their mutual relationship in chick neuroectoderm in vitro. Expression of NCAM, as detected by monoclonal and polyclonal antibodies, and development of junctional communication, as detected by extensive cell-to-cell transfer of 400-500-D fluorescent tracers, occurred in cultures from stage-2 embryos onward. Both expressions presumably required primary induction. The differentiating cells formed discrete fields of expression on the second to third day in culture, with the NCAM fields coinciding with the junctional communication fields delineated by the tracers. Other neural differentiations developed in the following order: tetanus toxin receptors, neurofilament protein, and neurite outgrowth. Chronic treatment with antibody Fab fragments against NCAM interfered with the development of communication, suggesting that NCAM-mediated adhesion promotes formation of cell-to-cell channels. Temperature-sensitive mutant Rous sarcoma virus blocked (reversibly) communication and the subsequent development of neurofilament protein and neurites, but expression of NCAM continued. PMID:2834404

1988-01-01

345

NbCN Josephson junctions with AlN barriers  

NASA Astrophysics Data System (ADS)

Niobium carbonitride (NbCN) Josephson circuits can operate over a wider temperature range than either niobium or niobium nitride circuits. Higher operating temperature places NbCN technology more comfortably within the range of closed-cycle refrigerators, a key factor in aerospace applications. Tunnel junctions have been fabricated from NbCN films with transition temperatures up to 18 k. High-quality NbCN tunnel junction fabrication generally requires low stress films with roughness less than the barrier thickness (about 20 A). Scanning tunneling microscopy was developed as a tool for measuring and optimizing film smoothness. Junctions formed in situ with AlN tunneling barriers show reproducible I-V characteristics. Unlike NbN, NbCN oxidizes readily, enabling junction definition by a modified SNAP process. This SNAP lithography technique successfully produced NbCN/AlN/NbCN junctions with Vm values (at 3 mV) up to 27 mV.

Thomasson, S. L.; Murduck, J. M.; Chan, H.

1991-03-01

346

A submicrometer Nb/AlO(x)/Nb Josephson junction  

NASA Astrophysics Data System (ADS)

High-quality, submicrometer Nb/AlO(x)/Nb Josephson junctions were fabricated. The junction area was defined by anodizing an upper Nb electrode using a thin SiO2 mask. By utilizing the anodized Nb as an etch stop during the reactive ion etching of the contact hole in an SiO2 insulator, a junction could be made smaller than the contact hole size. Using stress-free Nb for the junction electrodes was crucial in achieving good current-voltage characteristics. High-quality Nb/AlO(x)/Nb junctions as small as 0.7-micron square were produced. The quality parameter V(m) was greater than 30 mV for a j(c) of 6800 A/sq cm.

Imamura, Takeshi; Hasuo, Shinya

1988-08-01

347

Hybrid magnetic tunnel junction/spin filter device  

SciTech Connect

Surfaces and interfaces of complex oxides materials provide a rich playground for the exploration of novel magnetic properties not found in the bulk but also the development of functional interfaces to be incorporated into applications. We have recently been able to demonstrate a new type of hybrid spin filter/ magnetic tunnel junction. Our hybrid spin-filter/magnetic-tunnel junction devices are epitaxial oxide junctions of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and Fe{sub 3}O{sub 4} electrodes with magnetic NiMn{sub 2}O{sub 4} barrier layers. Depending on whether the barrier is in a paramagnetic or ferromagnetic state, the junction exhibits magnetic tunnel junction behavior where the spin polarized conduction is dominated by the electrode-barrier interface or spin filter behavior where conduction is dominated by barrier layer magnetism.

Suzuki, Y.; Nelson-Cheeseman, B.; Wong, F.; Chopdekar, R.; Arenholz, E.; Chi, Miaofang; Browning, Nigel

2008-07-10

348

A multilayered approach to superconducting tunnel junction x ray detectors  

NASA Technical Reports Server (NTRS)

'First generation' superconducting tunnel junction X-ray detectors (characterized by a single tunnel junction in direct contact with its substrate, with totally external amplification) remain more than an order of magnitude away from their theoretical energy resolutions which are in the order of eV's. The difficulties that first generation devices are encountering are being attacked by a 'second generation' of superconducting X-ray detector designs including quasiparticle trapping configurations and Josephson junction arrays. A second generation design concept, the multilayered superconducting tunnel junction X-ray detector, consisting of tens to hundreds of tunnel junctions stacked on top of one another (a superlattice), is presented. Some of the possibilities of this engineered materials approach include the tuning of phonon transmission characteristics of the material, suppression of parasitic quasiparticle trapping and intrinsic amplification.

Rippert, E. D.; Song, S. N.; Ketterson, J. B.; Maglic, S. R.; Lomatch, S.; Thomas, C.; Cheida, M. A.; Ulmer, M. P.

1992-01-01

349

The role of tight junctions in mammary gland function.  

PubMed

Tight junctions (TJ) are cellular structures that facilitate cell-cell communication and are important in maintaining the three-dimensional structure of epithelia. It is only during the last two decades that the molecular make-up of TJ is becoming unravelled, with two major transmembrane-spanning structural protein families, called occludin and claudins, being the true constituents of the TJ. These TJ proteins are linked via specific scaffolding proteins to the cell's cytoskeleton. In the mammary gland TJ between adjacent secretory epithelial cells are formed during lactogenesis and are instrumental in establishing and maintaining milk synthesis and secretion, whereas TJ integrity is compromised during mammary involution and also as result of mastitis and periods of mammary inflamation (including mastitis). They prevent the paracellular transport of ions and small molecules between the blood and milk compartments. Formation of intact TJ at the start of lactation is important for the establishment of the lactation. Conversely, loss of TJ integrity has been linked to reduced milk secretion and mammary function and increased paracellular transport of blood components into the milk and vice versa. In addition to acting as a paracellular barrier, the TJ is increasingly linked to playing an active role in intracellular signalling. This review focusses on the role of TJ in mammary function of the normal, non-malignant mammary gland, predominantly in ruminants, the major dairy producing species. PMID:24249583

Stelwagen, Kerst; Singh, Kuljeet

2014-03-01

350

Investigation of redox processes at semiconductor electrode liquid junctions  

SciTech Connect

Research in fundamental aspects of photoelectrochemical cells has been in the following areas: chemical probes for hot carrier processes, electrostatic theory for describing electrical interactions at interfaces, and kinetics of electron transfer at ideal semiconductor solution interfaces. Our goal is to achieve a better understanding of dark and photo-induced current flow at the semiconductor electrode/redox electrolyte interface (SEI) so that devices and processes utilizing this interface for solar energy conversion can be developed or improved. Our most important accomplishment has been the development of a redox system capable of detecting hot electrons at the p-InP/acetonitrile interface. Also, we have examined electrostatic theory for the image potential of an ion as a function of distance from the SEI. Finally, our group was one of the first to realize that the 2-dimensional metal chalcogenides (MC) are excellent materials for fundamental studies of electron transfer at the SEI. One of the chief potential advantages for use of MC's is the formation of semiconductor/liquid junctions with nearly ideal electrochemical properties. 27 refs., 1 fig.

Koval, C.A.

1990-08-01

351

Emerging multifunctional roles of Claudin tight junction proteins in bone.  

PubMed

The imbalance between bone formation and resorption during bone remodeling has been documented to be a major factor in the pathogenesis of osteoporosis. Recent evidence suggests a significant role for the tight junction proteins, Claudins (Cldns), in the regulation of bone remodeling processes. In terms of function, whereas Cldns act "canonically" as key determinants of paracellular permeability, there is considerable recent evidence to suggest that Cldns also participate in cell signaling, ie, a "noncanonical function". To this end, Cldns have been shown to regulate cell proliferation, differentiation, and gene expression in a variety of cell types. The present review will discuss Cldns' structure, their expression profile, regulation of expression, and their canonical and non- canonical functions in general with special emphasis on bone cells. In order to shed light on the noncanonical functions of Cldns in bone, we will highlight the role of Cldn-18 in regulating bone resorption and osteoclast differentiation. Collectively, we hope to provide a framework for guiding future research on understanding how Cldns modulate osteoblast and osteoclast function and overall bone homeostasis. Such studies should provide valuable insights into the pathogenesis of osteoporosis, and may highlight Cldns as novel targets for the diagnosis and therapeutic management of osteoporosis. PMID:24758302

Alshbool, Fatima Z; Mohan, Subburaman

2014-07-01

352

Structured chaos in a devil's staircase of the Josephson junction.  

PubMed

The phase dynamics of Josephson junctions (JJs) under external electromagnetic radiation is studied through numerical simulations. Current-voltage characteristics, Lyapunov exponents, and Poincaré sections are analyzed in detail. It is found that the subharmonic Shapiro steps at certain parameters are separated by structured chaotic windows. By performing a linear regression on the linear part of the data, a fractal dimension of D?=?0.868 is obtained, with an uncertainty of ±0.012. The chaotic regions exhibit scaling similarity, and it is shown that the devil's staircase of the system can form a backbone that unifies and explains the highly correlated and structured chaotic behavior. These features suggest a system possessing multiple complete devil's staircases. The onset of chaos for subharmonic steps occurs through the Feigenbaum period doubling scenario. Universality in the sequence of periodic windows is also demonstrated. Finally, the influence of the radiation and JJ parameters on the structured chaos is investigated, and it is concluded that the structured chaos is a stable formation over a wide range of parameter values. PMID:25273195

Shukrinov, Yu M; Botha, A E; Medvedeva, S Yu; Kolahchi, M R; Irie, A

2014-09-01

353

Differential phosphorylation of the gap junction protein connexin43 in junctional communication-competent and -deficient cell lines  

Microsoft Academic Search

Connexin43 is a member of the highly ho- mologous connexin family of gap junction proteins. We have studied how connexin monomers are assem- bled into functional gap junction plaques by examining the biosynthesis of connexin43 in cell types that differ greatly in their ability to form functional gap junc- tions. Using a combination of metabolic radiolabeling and immunoprecipitation, we have

Linda S. Musil; Bruce A. Cunningham; Gerald M. Edelman; Daniel A. Goodenough

1990-01-01

354

Source/Drain Junctions and Contacts for 45 nm CMOS and Beyond  

NASA Astrophysics Data System (ADS)

One of the greatest challenges for future CMOS generations is to limit the series resistance of source/drain junctions and their contacts to a small fraction of the channel `on' resistance. This challenge is paused by structural changes in transistor design as well as fundamental limitations of silicon as a semiconductor. It is anticipated that junctions that rely solely on ion-implantation combined with an advanced annealing technique will not meet our expectations beyond the 45 nm node. Fundamentally different processes and new materials are needed to meet the future requirements. Starting with the 90 nm technology node, we have already begun to see examples of departures from the conventional junction formation methods. A good example is Intel's 90 nm technology process featuring recessed Si1-xGexsource/drain junctions incorporated to address the series resistance concerns and to introduce uniaxial strain into the channel for enhanced mobility. It is predicted that within a few years the conventional planar MOSFET will be replaced with one of the so-called "non-classical" transistor structures, which include the fully-depleted SOI, FINFET and various structures proposed for enhanced carrier mobility via strain engineering. Unfortunately, these structures bring their own source/drain integration challenges requiring further innovations in materials and processes. This paper presents an overview of the key source/drain challenges with emphasis on MOSFET series resistance. Potential solutions to these challenges with emphasis on applications of Si1-xGexin source/drain engineering will be discussed in reference to various transistor structures currently considered as potential candidates for future CMOS generations.

Ozturk, Mehmet C.; Liu, Jing

2005-09-01

355

Optical and electrical simulations of two-junction III-V nanowires on Si solar cell  

NASA Astrophysics Data System (ADS)

A coupled optoelectronic simulation was used to theoretically assess the performance of core-shell GaInP nanowires array (NWA)/Si thin-film two-junction solar cell. Outstanding light harvesting rooted from the strong light trapping and the formation of Fabry-Pérot optical cavity in the NWA enables the cell to produce high photocurrent. From the detailed balance calculation, above 32% of efficiency could be obtained at the current matching geometries. Coupled optoelectronic simulation shows that current matching can be easily achieved even under relatively high recombination rate. A promising efficiency of 27.1% is obtained for the proposed cell with appropriate nanowires surface passivation.

Bu, Shaojiang; Li, Xinhua; Wen, Long; Zeng, Xuesong; Zhao, Yufeng; Wang, Wenbo; Wang, Yuqi

2013-01-01

356

A Silicon Nanocrystal Schottky Junction Solar Cell produced from Colloidal Silicon Nanocrystals  

PubMed Central

Solution-processed semiconductors are seen as a promising route to reducing the cost of the photovoltaic device manufacture. We are reporting a single-layer Schottky photovoltaic device that was fabricated by spin-coating intrinsic silicon nanocrystals (Si NCs) from colloidal suspension. The thin-film formation process was based on Si NCs without any ligand attachment, exchange, or removal reactions. The Schottky junction device showed a photovoltaic response with a power conversion efficiency of 0.02%, a fill factor of 0.26, short circuit-current density of 0.148 mA/cm2, and open-circuit voltage of 0.51 V. PMID:20676200

2010-01-01

357

Fabrication of p(+)-n junction GaAs solar cells by a novel method  

NASA Technical Reports Server (NTRS)

A novel method for making p(+)-n diffused junction GaAs solar cells, with the formation of a diffusion source, an anti-reflective coating, and a protective cover glass in a single chemical-vapor deposition operation is discussed. Consideration is given to device fabrication and to solar-cell characteristics. The advantages of the technique are that the number of process steps is kept to an absolute minimum, the fabrication procedure is low-cost, and the GaAs surface is protected during the entire operation.

Ghandhi, S. K.; Mathur, G.; Rode, H.; Borrego, J. M.

1984-01-01

358

Treatment of Ruptured Saccular Aneurysms of the Fenestrated Vertebrobasilar Junction with Balloon Remodeling Technique  

PubMed Central

Summary Fenestration of the intracranial arteries is a relatively common occurrence. This anatomic variation may predispose to aneurysm formation at certain sites. Treatment of such aneurysms is difficult as it may occlude one of the limbs of fenestration with resultant deficit. Thus, preservation of both the limbs with adequate exclusion of the aneurysm from the circulation should be the aim of any treatment. We describe a series of four cases of ruptured aneurysms arising from a fenestrated vertebrobasilar junction treated with endovascular balloon remodeling technique. PMID:24070077

Gupta, Vivek; Ahuja, Chirag K; Khandelwal, N; Kumar, Ajay; Gupta, S K

2013-01-01

359

Two Bayesian methods for junction classification.  

PubMed

We propose two Bayesian methods for junction classification which evolve from the Kona method: a region-based method and an edge-based method. Our region-based method computes a one-dimensional (1-D) profile where wedges are mapped to intervals with homogeneous intensity. These intervals are found through a growing-and-merging algorithm driven by a greedy rule. On the other hand, our edge-based method computes a different profile which maps wedge limits to peaks of contrast, and these peaks are found through thresholding followed by nonmaximum suppression. Experimental results show that both methods are more robust and efficient than the Kona method, and also that the edge-based method outperforms the region-based one. PMID:18237911

Cazorla, Miguel A; Escolano, Francisco

2003-01-01

360

Quantum Computing with Atomic Josephson Junction Arrays  

E-print Network

We present a quantum computing scheme with atomic Josephson junction arrays. The system consists of a small number of atoms with three internal states and trapped in a far-off resonant optical lattice. Raman lasers provide the "Josephson" tunneling, and the collision interaction between atoms represent the "capacitive" couplings between the modes. The qubit states are collective states of the atoms with opposite persistent currents. This system is closely analogous to the superconducting flux qubit. Single qubit quantum logic gates are performed by modulating the Raman couplings, while two-qubit gates result from a tunnel coupling between neighboring wells. Readout is achieved by tuning the Raman coupling adiabatically between the Josephson regime to the Rabi regime, followed by a detection of atoms in internal electronic states. Decoherence mechanisms are studied in detail promising a high ratio between the decoherence time and the gate operation time.

Lin Tian; P. Zoller

2003-06-12

361

Quantum computing with atomic Josephson junction arrays  

SciTech Connect

We present a quantum computing scheme with atomic Josephson junction arrays. The system consists of a small number of atoms with three internal states and trapped in a far-off-resonant optical lattice. Raman lasers provide the 'Josephson' tunneling, and the collision interaction between atoms represent the 'capacitive' couplings between the modes. The qubit states are collective states of the atoms with opposite persistent currents. This system is closely analogous to the superconducting flux qubit. Single-qubit quantum logic gates are performed by modulating the Raman couplings, while two-qubit gates result from a tunnel coupling between neighboring wells. Readout is achieved by tuning the Raman coupling adiabatically between the Josephson regime to the Rabi regime, followed by a detection of atoms in internal electronic states. Decoherence mechanisms are studied in detail promising a high ratio between the decoherence time and the gate operation time.

Tian Lin; Zoller, P. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria)

2003-10-01

362

Anatomy and development of the craniovertebral junction.  

PubMed

The occipital bone is the upper end of the somatic spine, limited cranially by the tentorium. The bony craniovertebral junction (caudal occiput, atlas, and axis) is interposed between the unsegmented occipital and the intersegmental spinal sclerotomes, separated from the occiput and C3 by the intrasegmental clefts of O4 and C2 sclerotomes, respectively. It retains a primitive segmental hypocentrum (anterior arch of C1) and is unsegmented from caudal O4 to cranial C2 half-sclerotomes (axis). Its morphology relates to the dual function of providing support and mobility (visual/olfactory/auditory pursuit, oral prehension) to the head. The early notochord passes through the odontoid tip to the basiocciput surface before entering the clivus up to the craniopharyngeal canal; later, the rostralmost chordal remnant is the C2/3 nucleus pulposus. Chondrification starts in the second fetal month and ossification in the fetal or postnatal periods depending on the structure. PMID:21822704

Raybaud, Charles

2011-12-01

363

[Bifurcational diverticulum ("aneurisms") of brain arterial junctions].  

PubMed

The results of clinico-morfological investigation of 220 arteries of the brain base from dead patients with aneurisms are in the article. The new facts and terms such as bifurcational hemodynamic aneurisms, segmental arterial ring of the brain and aneurysmal disease of the brain have been introduced. We have showed that aneurisms forms in the area of bifurcation, but not in linear segments of vessels. A junction of arteries in the bifurcation of vessels, formed by connective tissue, units muscle segments and takes place in development of aneurisms. The term of "aneurism" as a saccular evagination of all layers of arterial wall was prejudiced. A term as "diverticulum" could be use for denomination of evagination. Two types of aneurysmal disease of the brain clinical course have been separated out. The fist one is dysembryoplastic type with connective tissue deficiency and the second one--involutional hypertensive type at patients with long-term arterial hypertension. PMID:22712310

Medvedev, Iu A; Zabrodskaia, Iu M; Razmologova, O Iu; Sivtsova, E V

2012-01-01

364

[Plication of the sapheno-femoral junction].  

PubMed

Plication of the long saphena at the sapheno-femoral junction (SFJ) is an alternative to flush ligation and stripping. This technique abolishes reflux at the SFJ without altering the vein which may be used for arterial surgery or coronary grafting. The selection of the candidate for plication is done with ambulatory venous pressure measurements and duplex scanning which indicate and quantify the superficial incompetence. The plication of the SFJ reduces the calibre of the vein to 60-70% for a length of 1.5 cm allowing the valvular cusps to close when flow in the femoral vein is reversed. In this study we evaluated 20 limbs (in 20 patients) 6, 12 and 24 months after plication. Venous reflux was significantly reduced with improvement of signs and symptoms. In conclusion, SFJ plication seems to be an effective physiological alternative to flush ligation. However long term results (greater than 5 years) must be still evaluated. PMID:1766560

Ricci, A; Laurora, G; Cesarone, M R; Belcaro, G

1991-10-31

365

Ruptured venous aneurysm of cervicomedullary junction  

PubMed Central

Background: Ruptured venous aneurysm is often seen with arterio-venous malformation (AVM) or developmental venous anomaly (DVA). However, isolated venous aneurysm is unusual. Case Description: We present a case of ruptured venous aneurysm that presented with subarachnoid hemorrhage (SAH) and intraventricular hemorrhage (IVH). Digital substraction angiography (DSA) revealed a saccular contrast filling pouch in the left lateral aspect of cervicomedullary junction (CMJ). Endovascular intervention was not a viable option. During surgery, a saccular pliable structure approx. 1.5 × 1 cm was found in the subarachnoid space that was clipped and excised. There were no arterial feeders, no evidence of surrounding AVM, and no dilated perimedullary vein. Conclusion: This is perhaps the first reported case of ruptured venous aneurysm (without associated AVM) of CMJ, which was successfully managed surgically. The possible etiologies remain an unnoticed head trauma or a congenital vessel wall abnormality. Surgically clipping and excision remains the treatment of choice for such lesion. PMID:24575317

Aggarwal, Ashish; Salunke, Pravin; Futane, Sameer; Mathuriya, S. N.; Kumar, Ajay; Mukherjee, K. K.; Radotra, B. D.

2014-01-01

366

Ultrafast endocytosis at Caenorhabditis elegans neuromuscular junctions  

PubMed Central

Synaptic vesicles can be released at extremely high rates, which places an extraordinary demand on the recycling machinery. Previous ultrastructural studies of vesicle recycling were conducted in dissected preparations using an intense stimulation to maximize the probability of release. Here, a single light stimulus was applied to motor neurons in intact Caenorhabditis elegans nematodes expressing channelrhodopsin, and the animals rapidly frozen. We found that docked vesicles fuse along a broad active zone in response to a single stimulus, and are replenished with a time constant of about 2 s. Endocytosis occurs within 50 ms adjacent to the dense projection and after 1 s adjacent to adherens junctions. These studies suggest that synaptic vesicle endocytosis may occur on a millisecond time scale following a single physiological stimulus in the intact nervous system and is unlikely to conform to current models of endocytosis. DOI: http://dx.doi.org/10.7554/eLife.00723.001 PMID:24015355

Watanabe, Shigeki; Liu, Qiang; Davis, M Wayne; Hollopeter, Gunther; Thomas, Nikita; Jorgensen, Nels B; Jorgensen, Erik M

2013-01-01

367

Studies of silicon pn junction solar cells  

NASA Technical Reports Server (NTRS)

Modifications of the basic Shockley equations that result from the random and nonrandom spatial variations of the chemical composition of a semiconductor were developed. These modifications underlie the existence of the extensive emitter recombination current that limits the voltage over the open circuit of solar cells. The measurement of parameters, series resistance and the base diffusion length is discussed. Two methods are presented for establishing the energy bandgap narrowing in the heavily-doped emitter region. Corrections that can be important in the application of one of these methods to small test cells are examined. Oxide-charge-induced high-low-junction emitter (OCI-HLE) test cells which exhibit considerably higher voltage over the open circuit than was previously seen in n-on-p solar cells are described.

Lindholm, F. A.; Neugroschel, A.

1977-01-01

368

Export of a Toxoplasma gondii Rhoptry Neck Protein Complex at the Host Cell Membrane to Form the Moving Junction during Invasion  

Microsoft Academic Search

One of the most conserved features of the invasion process in Apicomplexa parasites is the formation of a moving junction (MJ) between the apex of the parasite and the host cell membrane that moves along the parasite and serves as support to propel it inside the host cell. The MJ was, up to a recent period, completely unknown at the

Sébastien Besteiro; Adeline Michelin; Joël Poncet; Jean-François Dubremetz; Maryse Lebrun

2009-01-01

369

Carbon nanotube Y-junctions for Nanoscale Electronics  

NASA Astrophysics Data System (ADS)

Carbon Nanotube (CNT) based electronics offer significant potential, as a nanoscale alternative to silicon based devices, for novel molecular electronics technologies. To realize truly nanoelectronic architecture, it is desirable to have a fully integrated nanotube based technology, where both devices and interconnects are based on CNTs. With this aim in mind, we report on the electrical properties of CNT based Y-junctions. The carrier delocalization and the inevitable presence of catalyst particles, introduced during growth, at the junction region induce a net charge and scattering which can be exploited in constructing electronic devices. We have assembled and electrically characterized the DC resistance and the AC impedance of several Y-junction devices^2 with possibilities for switching and transistor related applications. These experiments alert us to the vast potentialities of Y-junction devices in the development of nanoelectronic components including inverters, logic gates, and frequency mixers. An electrical impedance model of a MWNT Y-junction will be presented which will help gain an understanding of the current transport mechanisms in these nanostructures. 1. P. Bandaru et al, ``Novel electrical switching behavior and logic in carbon nanotube Y-junctions'', Nature Materials, vol. 4(9), 663-666, (2005) 2. N. Gothard, et al. ``Controlled growth of Y-junction nanotubes using Ti-doped vapor catalyst'', Nanoletters 4, 213-217 (2004).

Bandaru, Prabhakar; Daraio, Chiara; Jin, Sungho; Rao, Apparao

2006-03-01

370

Structure activity relationship of synaptic and junctional neurotransmission  

PubMed Central

Chemical neurotransmission may include transmission to local or remote sites. Locally, contact between ‘bare’ portions of the bulbous nerve terminal termed a varicosity and the effector cell may be in the form of either synapse or non-synaptic contact. Traditionally, all local transmissions between nerves and effector cells are considered synaptic in nature. This is particularly true for communication between neurons. However, communication between nerves and other effectors such as smooth muscles has been described as nonsynaptic or junctional in nature. Nonsynaptic neurotransmission is now also increasing recognized in the CNS. This review focuses on the relationship between structure and function that orchestrate synaptic and junctional neurotransmissions. A synapse is a specialized focal contact between the presynaptic active zone capable for ultrafast release of soluble transmitters and the postsynaptic density that cluster ionotropic receptors. The presynaptic and the postsynaptic areas are separated by the ‘closed’ synaptic cavity. The physiological hallmark of the synapse is ultrafast postsynaptic potentials lasting in milliseconds. In contrast, junctions are juxtapositions of nerve terminals and the effector cells without clear synaptic specializations and the junctional space is ‘open’ to the extracellular space. Based on the nature of the transmitters, postjunctional receptors and their separation from the release sites, the junctions can be divided into ‘close’ and ‘wide’ junctions. Functionally, the ‘close’ and the ‘wide’ junctions can be distinguished by postjunctional potentials lasting ~1 second and 10s of seconds, respectively. Both synaptic and junctional communications are common between neurons; however, junctional transmission is the rule at many neuro-non-neural effectors. PMID:23535140

Goyal, Raj K; Chaudhury, Arun

2013-01-01

371

Role of N-Cadherin cis and trans Interfaces in the Dynamics of Adherens Junctions in Living Cells  

PubMed Central

Cadherins, Ca2+-dependent adhesion molecules, are crucial for cell-cell junctions and remodeling. Cadherins form inter-junctional lattices by the formation of both cis and trans dimers. Here, we directly visualize and quantify the spatiotemporal dynamics of wild-type and dimer mutant N-cadherin interactions using time-lapse imaging of junction assembly, disassembly and a FRET reporter to assess Ca2+-dependent interactions. A trans dimer mutant (W2A) and a cis mutant (V81D/V174D) exhibited an increased Ca2+-sensitivity for the disassembly of trans dimers compared to the WT, while another mutant (R14E) was insensitive to Ca2+-chelation. Time-lapse imaging of junction assembly and disassembly, monitored in 2D and 3D (using cellular spheroids), revealed kinetic differences in the different mutants as well as different behaviors in the 2D and 3D environment. Taken together, these data provide new insights into the role that the cis and trans dimers play in the dynamic interactions of cadherins. PMID:24312555

Junek, Stephan; Vogel, Dirk; Ansari, Nariman; Stelzer, Ernst H. K.; Schuman, Erin

2013-01-01

372

Pick1 modulates ephrinB1-induced junctional disassembly through an association with ephrinB1.  

PubMed

Members of the Eph family have been implicated in the formation of cell-cell boundaries, cell movement, and positioning during development in the context of cancer progression. De-regulation of this signaling system is linked to the promotion of more aggressive and metastatic tumor phenotypes in a large variety of human cancers, including breast, lung, and prostate cancer, melanoma, and leukemia. Thus, it is interesting to consider the case of cancer progression where de-regulation of the Eph/ephrin signaling system results in invasion and metastasis. Here, we present evidence that Pick1, one of the essential components of the adherens junction, recovers ephrinB1-induced cell-cell de-adhesion. Loss of Pick1 leads to dissociation of epithelial cells via disruption of the adherens junction, a phenotype similar to ephrinB1 overexpression. In addition, overexpressed ephrinB1-induced disruption of the adherens junction is rescued via binding to Pick1. These data indicate that Pick1 is involved in regulating the cell-cell junction in epithelial cells, and this may influence therapeutic strategy decisions with regards to cell adhesion molecules in metastatic disease. PMID:24937449

Son, Jungeun; Park, Mi Seon; Park, Inji; Lee, Hyun-Kyung; Lee, Soo-Ho; Kang, Byungwoo; Min, Byung-Hwa; Ryoo, Jaewoong; Lee, Sanggyu; Bae, Jong-Sup; Kim, Sang-Hyun; Park, Mae-Ja; Lee, Hyun-Shik

2014-07-18

373

Lateral MoS2 p-n Junction Formed by Chemical Doping for Use in High-Performance Optoelectronics.  

PubMed

This paper demonstrates a technique to form a lateral homogeneous 2D MoS2 p-n junction by partially stacking 2D h-BN as a mask to p-dope MoS2. The fabricated lateral MoS2 p-n junction with asymmetric electrodes of Pd and Cr/Au displayed a highly efficient photoresponse (maximum external quantum efficiency of ?7000%, specific detectivity of ?5 × 10(10) Jones, and light switching ratio of ?10(3)) and ideal rectifying behavior. The enhanced photoresponse and generation of open-circuit voltage (VOC) and short-circuit current (ISC) were understood to originate from the formation of a p-n junction after chemical doping. Due to the high photoresponse at low VD and VG attributed to its built-in potential, our MoS2 p-n diode made progress toward the realization of low-power operating photodevices. Thus, this study suggests an effective way to form a lateral p-n junction by the h-BN hard masking technique and to improve the photoresponse of MoS2 by the chemical doping process. PMID:25131298

Choi, Min Sup; Qu, Deshun; Lee, Daeyeong; Liu, Xiaochi; Watanabe, Kenji; Taniguchi, Takashi; Yoo, Won Jong

2014-09-23

374

Single molecular shuttle-junction: Shot noise and decoherence  

NASA Astrophysics Data System (ADS)

Single molecular shuttle-junction is one kind of nanoscale electromechanical tunneling system. In this junction, a molecular island oscillates depending on its charge occupation, and this charge dependent oscillation leads to modulation of electron tunneling through the molecular island. This paper reviews recent development on the study of current, shot noise and decoherence of electrons in the single molecular shuttle-junction. We will give detail discussions on this topic using the typical system model, the theory of fully quantum master equation and the Aharonov-Bohm interferometer.

Lai, Wenxi; Zhang, Chao; Ma, Zhongshui

2014-09-01

375

Selective niobium anodization process for fabricating Josephson tunnel junctions  

NASA Astrophysics Data System (ADS)

A novel process for fabricating refractory sperconducting tunnel junctions is described, which is useful with both deposited and native oxide barriers. The distinguishing feature of the method is that the entire superconductor-barrier-superconductor sandwich is formed before the patterning of any layer. Isolated Josephson junctions are then formed by anodizing through the upper electrode, while the devices themselves are protected by a photoresist mask. Using this process, Nb-Si:H-Nb junctions have been fabricated, whose product of critical current and subgap resistance exceeds 10 mV and whose critical current density varies by about 50% over a 2-in. diameter wafer.

Kroger, H.; Smith, L. N.; Jillie, D. W.

1981-08-01

376

Statistical mechanics of strings with Y-junctions  

E-print Network

We investigate the Hagedorn transitions of string networks with Y-junctions as may occur, for example, with (p,q) cosmic superstrings. In a simplified model with three different types of string, the partition function reduces to three generalised coupled XY models. We calculate the phase diagram and show that, as the system is heated, the lightest strings first undergo the Hagedorn transition despite the junctions. There is then a second, higher, critical temperature above which infinite strings of all tensions, and junctions, exist. Conversely, on cooling to low temperatures, only the lightest strings remain, but they collapse into small loops.

R. J. Rivers; D. A. Steer

2008-03-27

377

Using pn junction depletion regions to position epitaxial nanowires  

NASA Astrophysics Data System (ADS)

Si nanowires were grown horizontally using the vapor-liquid-solid method from vertical {111} surfaces etched into a (110) Si substrate. The nanowires were catalyzed by negatively charged, citrate-stabilized, Au nanoparticles. The negative charge on the nanoparticles was used to position them along a positively charged depletion region formed by a pn junction. By positioning the nanoparticle catalysts, the epitaxial Si nanowires catalyzed by the nanoparticles were also positioned along this junction. The structure that best positioned the nanowires was highly doped n-type material on a lightly doped p-type substrate. Enhanced positioning of the nanowires was accomplished using a reverse bias across the pn junction.

Quitoriano, Nathaniel J.; Kamins, Theodore I.

2007-08-01

378

Statistical mechanics of strings with Y-junctions  

SciTech Connect

We investigate the Hagedorn transitions of string networks with Y-junctions as may occur, for example, with (p,q) cosmic superstrings. In a simplified model with three different types of string, the partition function reduces to three generalized coupled XY models. We calculate the phase diagram and show that, as the system is heated, the lightest strings first undergo the Hagedorn transition despite the junctions. There is then a second, higher, critical temperature above which infinite strings of all tensions, and junctions, exist. Conversely, on cooling to low temperatures, only the lightest strings remain, but they collapse into small loops.

Rivers, R. J.; Steer, D. A. [Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom); APC, Batiment Condorcet, 10 rue Alice Domon et Leonie Duquet 75205 Paris Cedex 13 (France) and CERN Physics Department, Theory Division, CH-1211 Geneva 23 (Switzerland)

2008-07-15

379

Stabilization of Ion Concentration Polarization Using a Heterogeneous Nanoporous Junction  

PubMed Central

We demonstrate a recycled ion – flux through heterogeneous nanoporous junctions, which induce stable ion concentration polarization (ICP) with an electric field. The nanoporous junctions are based on integration of ionic hydrogels whose surfaces are negatively- and positively- charged for cationic selectivity and anionic selectivity, respectively. It is shown that a ‘heterojunction’ structure with cationic selective hydrogels (CSH) and anionic selective hydrogels (ASH) can be matched up in a way to achieve continuous ion-flux operation for stable concentration gradient or ionic conductance. Furthermore, the combined junctions can be used to accumulate ions on a specific region of the device. PMID:20017532

Kim, Pilnam; Kim, Sung Jae; Han, Jongyoon; Suh, Kahp Y.

2010-01-01

380

Incompressible Turbulent Wing-Body Junction Flow  

NASA Technical Reports Server (NTRS)

The overall objective of this study is to contribute to the optimized design of fan bypass systems in advanced turbofan engines. Increasing the engine bypass ratios have provided a major boost in engine performance improvement over the last fifty years. An engine with high bypass ratio (11-16:1) such as the Advanced Ducted Propulsion (ADP) is being developed and is expected to provide an additional 25% improvement in overall efficiency over the early turbofans. Such significant improvements in overall efficiency would reduce the cost per seat mile, which is a major government and Industry challenge for the 21th century. The research is part of the Advanced Subsonic Technology (AST) program that involves a NASA, U.S. Industry and FAA partnership with the goal of a safe and highly productive global air transportation system. The immediate objective of the study is to perform numerical simulation of duct-strut interactions to elucidate the loss mechanisms associated with this configuration that is typical of advanced turbofan engines such as ADP. However, at present experimental data for a duct-strut configuration are not available. Thus, as a first step a wing-body junction flow would be studied and is the specific objective of the present study. At the outset it is to be recognized that while duct-strut interaction flow is similar to that of wing-body junction flows, there are some differences owing to the presence of a wall at both ends of the strut. Likewise, some differences are due to the sheared inflow (as opposed to a uniform inflow) velocity profile. It is however expected that some features of a wing-body junction flow would persist. Next, some of the salient aspects of the complex flow near a wing-body junction, as revealed by various studies reported in the literature will be reviewed. One of the principle characteristics of the juncture flow, is the presence of the mean flow components in a plane perpendicular to the direction of the oncoming free-stream flow. The lateral curvature of the wing/strat causes the oncoming turbulent layer to skew about am axis (x-axis) parallel to the plane (xz-plane) of the mean shear. This is the principle mechanism for the generation of secondary flow. Such skew-induced secondary flows are slow to be attenuated by Reynolds stresses. Additional contribution to the generation of secondary flow comes from anisotropies in Reynolds stresses. Upstream of the strut, the mean-vorticity is directed span wise (along the y-direction). The presence of secondary flow in the vicinity of the strut causes the vorticity to stretch around the obstacle in a horse-shoe shape, with each leg having a vorticity of the opposite sense. The blockage effect of the strut imposes a severe adverse pressure gradient on the oncoming turbulent shear layer, causing boundary layer separation ahead of the leading edge, resulting in a vortex that rolls up and flows downstream into the juncture region. The separation vortices trailing in the wake of the wing can alter the lift or drag characteristics of the surfaces downstream of the wing-body juncture. Likewise, on submarines, the wake flow behind the appendage can degrade the performance of the propeller located downstream. The complex nature of this flow is caused by the presence of all six components of Reynolds stresses. Devenport and Simpson report that in the vicinity of the horse-shoe vortex there is intense recirculation with turbulent stresses being much larger than those normally observed in turbulent flows. These features contribute to making this flow a challenge to predict numerically. Some of the past studies provide useful insights into this flow that would guide our numerical efforts. In measurements reported by Shabaka and Bradshaw, the eddy viscosity tensor is seen to be non-isotropic and has negative components in certain regions. In an effort to evaluate the closure assumptions of various turbulence models, Devenport and Simpson used their own extensive measurements in juncture flows around the nose of a wing-body junction. Measured values of me

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

1998-01-01

381

Part-type Segmentation of Articulated Voxel-Shapes using the Junction Rule  

E-print Network

in a new junction in the curve skeleton located near the intersection. We call this the junction rule-shapes based on the junction rule. The par- ticular curve-skeleton definition we use [DS06] associatesPart-type Segmentation of Articulated Voxel-Shapes using the Junction Rule Dennie Reniers1

Telea, Alexandru C.

382

“Tight” junctions in the sheath of normal and regenerating motor nerves of the crayfish, Orconectes virilis  

Microsoft Academic Search

“Tight” or occluding intercellular junctions occur between adjacent glial processes in normal and regenerating crayfish motor nerve sheaths. Although infrequent, these junctions possess the ridge and groove configuration characteristic of freeze-cleaved occluding junctions. When present, nerve sheath tight junctions consist of a single, or at most a few, parallel intramembrane ridges situated on the EF membrane face of the glial

Richard R. Shivers

1977-01-01

383

Controlling Factors of the Electric Field at the Triple Junction  

NASA Astrophysics Data System (ADS)

The metal-dielectric-vacuum junction is defined as the triple junction owned enhanced electric field, thus this special region is regarded as the location where primary electrons emission is favored. For electron emission, triple junction could affect both the flashover breakdown of insulators and the electron emission property of ferroelectric cathodes. In this study, we theoretically investigate the electric field enhancement in the triple-junction region. It is found that the key parameter to determine the field enhancement is the taper angle of the electrode and the relative permittivity of the dielectric. In addition, we first deduce the accurate expression of the electric field in this special region. The controlling parameters for determining the field enhancement are discussed in detail. We also discover the way to reduce the electric field of this region through simulation. The current analysis would be useful for both the electron emission enhancement and the issue of flashover breakdown.

Liu, Yang; Huang, Xu-Dong; Feng, Yu-Jun; He, Hong-Liang

2014-02-01

384

Terahertz detector with transmission-line type superconducting tunnel junctions  

NASA Astrophysics Data System (ADS)

We demonstrate a new type of terahertz detector with superconducting tunnel junctions. The detector has two long junctions integrated on both wings of a log-periodic antenna. In this type of detector, the long junction is a lossy transmission line working based on the Cooper-pair breaking, as well as a standing-wave resonance line working based on the photon-assisted tunneling. A prototype detector using Nb/Al/AlOx/Al/Nb junctions was fabricated, and the principle of the detector was verified. The prototype shows a gradual increase in sensitivity starting from 0.35 THz. We have also identified a resonance signal at 0.25 THz below the effective gap frequency.

Ariyoshi, S.; Takahashi, K.; Noguchi, T.; Kurakado, M.; Koga, K.; Furukawa, N.; Otani, C.

2012-07-01

385

Frustrated Rotations in Single-Molecule Junctions Young S. Park,,  

E-print Network

,3 When junctions are formed using gold metal electrodes, thiol links are frequently used.4,5 However with methyl iodide.10 3 and 4 were synthesized by hydrogenations of the corre- sponding benzodithiophene

Venkataraman, Latha

386

View of Highway 140 and Overhang Rock. Location of junction ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of Highway 140 and Overhang Rock. Location of junction with Old Coulterville Road behind rock. Looking north-northwest - All Year Highway, Between Arch Rock & Yosemite Valley, El Portal, Mariposa County, CA

387

Enhanced thermoelectric figure of merit in vertical graphene junctions  

NASA Astrophysics Data System (ADS)

In this work, we investigate thermoelectric properties of junctions consisting of two partially overlapped graphene sheets coupled to each other in the cross-plane direction. It is shown that because of the weak van-der Waals interactions between graphene layers, the phonon conductance in these junctions is strongly reduced, compared to that of single graphene layer structures, while their electrical performance is weakly affected. By exploiting this effect, we demonstrate that the thermoelectric figure of merit, ZT, can reach values higher than 1 at room temperature in junctions made of gapped graphene materials, for instance, graphene nanoribbons and graphene nanomeshes. The dependence of thermoelectric properties on the junction length is also discussed. This theoretical study hence suggests an efficient way to enhance thermoelectric efficiency of graphene devices.

Hung Nguyen, V.; Nguyen, M. Chung; Nguyen, Huy-Viet; Saint-Martin, J.; Dollfus, P.

2014-09-01

388

Atomic Layer Deposition of Tunnel Barriers for Superconducting Tunnel Junctions  

NASA Astrophysics Data System (ADS)

We demonstrate a technique for creating high quality, large area tunnel junction barriers for normal-insulating-superconducting or superconducting-insulating-superconducting tunnel junctions. We use atomic layer deposition and an aluminum wetting layer to form a nanometer scale insulating barrier on gold films. Electronic transport measurements confirm that single-particle electron tunneling is the dominant transport mechanism, and the measured current-voltage curves demonstrate the viability of using these devices as self-calibrated, low temperature thermometers with a wide range of tunable parameters. This work represents a promising first step for superconducting technologies with deposited tunnel junction barriers. The potential for fabricating high performance junction refrigerators is also highlighted.

Moyerman, Stephanie M.; Feng, Guangyuan; Krayer, Lisa; Stebor, Nathan; Keating, Brian G.

2014-08-01

389

Non-synaptic transmission at autonomic neuroeffector junctions Geoffrey Burnstock *  

E-print Network

, 2004b; Gabella, 1995). It also occurs in the central nervous system (see Vizi, this issue). Evidence the better known skeletal neuro- muscular junction; it is not a synapse with the well defined prejunctional

Burnstock, Geoffrey

390

Non-synaptic transmission at autonomic neuroeffector junctions Geoffrey Burnstock *  

E-print Network

in the central nervous system (see Vizi, this issue). Evidence in support of non-synaptic neuromuscular transmis differs in several important respects from the better known skeletal neuro- muscular junction

Burnstock, Geoffrey

391

24. OVERGROWN SECTION OF CORINTH ROAD BETWEEN JUNCTION OF RECONNOITERING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. OVERGROWN SECTION OF CORINTH ROAD BETWEEN JUNCTION OF RECONNOITERING ROAD AND THE TOWN OF SHILOH, CLOSED TO TRAFFIC IN 1960s, LOOKING TOWARDS TOWN. VIEW S. - Shiloh National Military Park Tour Roads, Shiloh, Hardin County, TN

392

Raman scattering in molecular junctions: a pseudoparticle formulation.  

PubMed

We present a formulation of Raman spectroscopy in molecular junctions based on a many-body state representation of the molecule. The approach goes beyond the previous effective single orbital formalism and provides a convenient way to incorporate computational methods and tools proven for equilibrium molecular spectroscopy into the realm of current carrying junctions. The presented framework is illustrated by first principle simulations of Raman response in a three-ring oligophenylene vinylene terminating in amine functional groups (OPV3) junction. The calculated shift in Stokes lines and estimate of vibrational heating by electric current agree with available experimental data. In particular, our results suggest that participation of the OPV3 cation in Raman scattering under bias may be responsible for the observed shift, and that the direction of the shift depends on renormalization of normal modes. This work is a step toward atomistic quantum ab initio modeling of the optical response of nonequilibrium electronic dynamics in molecular junctions. PMID:24447295

White, Alexander J; Tretiak, Sergei; Galperin, Michael

2014-02-12

393

Gap junction-mediated electrical transmission: Regulatory mechanisms and plasticity  

E-print Network

Gap junction-mediated electrical transmission: Regulatory mechanisms and plasticity Alberto E of synaptic transmission: chemical and electrical. While most efforts have been dedicated to the understanding of synaptic transmission: chemical and electrical. In chemical synapses, presynaptic electrical currents

Rash, John E.

394

Cambridge Grand Junction transit implementation : alternatives, scheduling, cost, and performance  

E-print Network

The Grand Junction railroad lies at the heart of East Cambridge adjacent to the Kendall Square business district and the Massachusetts Institute of Technology campus. Over the last one hundred years the railroad has gone ...

Iglesias Cuervo, Jesus

2012-01-01

395

Nonlinear microwave absorption in weak-link Josephson junctions  

NASA Astrophysics Data System (ADS)

A model, based on the resistively shunted junction theory, is developed and used to study microwave absorption in weak-link Josephson junctions in high-Tc superconductors. Both linear and nonlinear cases of microwave absorption in Josephson junctions are analyzed. A comparison of the model with microwave absorption loop theory is presented along with a general condition for the applicability of both models. The nonlinear case was solved numerically and the threshold points of sharp microwave absorption are presented. At these points, a 2? phase quantization takes place within each microwave cycle, leading to an onset of a sharp rise of absorption. Existence of the 2? dynamic quantization is the key to the interpretation of nonlinear microwave absorption data. The nonlinear microwave absorption model is extended to the study of nonuniformly coupled junctions, and a general statement for the applicability of such a model is presented.

Xie, L. M.; Wosik, J.; Wolfe, J. C.

1996-12-01

396

Thermoelectricity in atom-sized junctions at room temperatures  

PubMed Central

Atomic and molecular junctions are an emerging class of thermoelectric materials that exploit quantum confinement effects to obtain an enhanced figure of merit. An important feature in such nanoscale systems is that the electron and heat transport become highly sensitive to the atomic configurations. Here we report the characterization of geometry-sensitive thermoelectricity in atom-sized junctions at room temperatures. We measured the electrical conductance and thermoelectric power of gold nanocontacts simultaneously down to the single atom size. We found junction conductance dependent thermoelectric voltage oscillations with period 2e2/h. We also observed quantum suppression of thermovoltage fluctuations in fully-transparent contacts. These quantum confinement effects appeared only statistically due to the geometry-sensitive nature of thermoelectricity in the atom-sized junctions. The present method can be applied to various nanomaterials including single-molecules or nanoparticles and thus may be used as a useful platform for developing low-dimensional thermoelectric building blocks. PMID:24270238

Tsutsui, Makusu; Morikawa, Takanori; Arima, Akihide; Taniguchi, Masateru

2013-01-01

397

Balloon Photography of Earth Fissures Near Apache Junction  

NSDL National Science Digital Library

Hosted by Arizona State University, this site contains balloon photographs taken from above the Apache Junction. A series of geologic structures are shown by these photographs. It gives a comprehensive look at different aspects of this site.

2008-10-16

398

Interface Structure and Transport of Complex Oxide Junctions  

SciTech Connect

The interface structure and magnetism of hybrid magnetic tunnel junction-spin filter devices have been investigated and correlated with the transport behavior exhibited. Magnetic tunnel junctions made of theoretically predicted half-metallic electrodes (perovskite La0.7Sr0.3MnO3 and spinel Fe3O4) sandwiching a spinel NiMn2O4 tunnel barrier exhibit very high crystalline quality as observed by transmission electron microscopy. Structurally abrupt interfaces allow for the distinct magnetic switching of the electrodes as well as large junction magnetoresistance. The change in the magnetic anisotropy observed at the spinel-spinel interface supports the presence of limited interdiffusion and the creation of a magnetically soft interfacial layer, whose strong exchange coupling to the Fe3O4 electrode likely accounts for the low background magnetoresistance observed in these junctions, and the successful spin filtering when the barrier layer is ferrimagnetic.

Nelson-Cheeseman, B. B.; Wong, F.; Chopdekar, R. V.; Chi, M.; Arenholz, E.; Browning, N. D.; Suzuki, Y.

2008-02-01

399

Experimental realization of Josephson junctions for an atom SQUID.  

PubMed

We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor. PMID:24289693

Ryu, C; Blackburn, P W; Blinova, A A; Boshier, M G

2013-11-15

400

Experimental realization of Josephson junctions for an Atom SQUID  

E-print Network

We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor.

C. Ryu; A. A. Blinova; P. W. Blackburn; M. G. Boshier

2013-04-30

401

Experimental Realization of Josephson Junctions for an Atom SQUID  

NASA Astrophysics Data System (ADS)

We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor.

Ryu, C.; Blackburn, P. W.; Blinova, A. A.; Boshier, M. G.

2013-11-01

402

Electron transport in normal-metal/superconductor junctions  

E-print Network

On the basis of the Keldysh method of nonequilibrium systems, we develop a theory of electron tunneling in normal-metal-superconductor junctions. By using the tunneling Hamiltonian model (being appropriate for the tight-binding systems...

Yan, XZ; Zhao, HW; Hu, Chia-Ren.

2000-01-01

403

54. View of junction of unlined canal and lined canal, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

54. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

404

55. View of junction of unlined canal and lined canal, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

55. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

405

8. VIEW SOUTHWEST, DETAIL OF JUNCTION OF EAST AND NORTH ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. VIEW SOUTHWEST, DETAIL OF JUNCTION OF EAST AND NORTH ELEVATIONS AT PORCH ROOF LEVEL SHOWING GLAZED HEADERS AND BELT COURSE - David Sterrett House, State Game Lands Plot No. 169 (Upper Mifflin Township), Newville, Cumberland County, PA

406

A Novel Role of Human Holliday Junction Resolvase GEN1 in the Maintenance of Centrosome Integrity  

PubMed Central

The maintenance of genomic stability requires accurate genome replication, repair of DNA damage, and the precise segregation of chromosomes in mitosis. GEN1 possesses Holliday junction resolvase activity in vitro and presumably functions in homology driven repair of DNA double strand breaks. However, little is currently known about the cellular functions of human GEN1. In the present study we demonstrate that GEN1 is a novel centrosome associated protein and we characterize the various phenotypes associated with GEN1 deficiency. We identify an N-terminal centrosome localization signal in GEN1, which is required and sufficient for centrosome localization. We report that GEN1 depletion results in aberrant centrosome numbers associated with the formation of multiple spindle poles in mitosis, an increased number of cells with multi-nuclei, increased apoptosis and an elevated level of spontaneous DNA damage. We find homologous recombination severely impaired in GEN1 deficient cells, suggesting that GEN1 functions as a Holliday junction resolvase in vivo as well as in vitro. Complementation of GEN1 depleted cells with various GEN1 constructs revealed that centrosome association but not catalytic activity of GEN1 is required for preventing centrosome hyper-amplification, formation of multiple mitotic spindles, and multi-nucleation. Our findings provide novel insight into the biological functions of GEN1 by uncovering an important role of GEN1 in the regulation of centrosome integrity. PMID:23166748

Zhou, Dong-Ping; Xu, Qian; Li, Miao-Miao; Wang, Zhao-Qi; Tong, Wei-Min; Yang, Yun-Gui

2012-01-01

407

Inflammatory conditions induce gap junctional communication between rat Kupffer cells both in vivo and in vitro  

PubMed Central

Connexin43 (Cx43), a gap junction protein subunit, has been previously detected in Kupffer cells (KCs) during liver inflammation, however, KCs phagocytose cell debris that may include Cx43 protein, which could explain the detection of Cx43 in KCs. We determined that KCs express Cx43 and form gap junctions both in vivo and in vitro. In liver sections of animals treated with LPS, Cx43 was detected at ED2+ cells interfaces, indicating formation of GJ between KCs in vivo. In vitro, unstimulated KCs cultures did not form functional GJs, and expressed low levels of Cx43 that showed a diffuse intracellular distribution. In contrast, KCs treated with LPS plus IFN-?, expressed a greater amount of Cx43 at both the, protein and mRNA levels, and showed Cx43 at cell-cell contacts associated with higher dye coupling. In conclusion, activation of KCs in vivo or in vitro resulted in enhanced Cx43 expression levels and formation of GJ that might play relevant roles during liver inflammation. PMID:17900549

Eugenin, Eliseo A.; Gonzalez, Hernan E.; Sanchez, Helmuth A.; Branes, Maria C.; Saez, Juan C.

2007-01-01

408

Cavity-mode excitation in a Josephson tunnel junction  

Microsoft Academic Search

Using Takanaka's theory of the zero-field dc-current steps of a Josephson tunnel junction, we have studied the effect of the junction Q factor on the shape of the current step near the first even-order resonant voltage V=hnuce, where nuc is the frequency of the fundamental cavity mode. In addition, we have found that the effect of a magnetic field on

Jhy-Jiun Chang; J. T. Chen

1980-01-01

409

Cingulin, a new peripheral component of tight junctions  

Microsoft Academic Search

The tight junction (zonula occludens), a belt-like region of contact between cells of polarized epithelia, serves as a selective barrier to small molecules and as a total barrier to large molecules1,2, and is involved in the separation between lumenal and basolateral compartments of the epithelium3,4. In the electron microscope, tight junctions show focal regions of apparent fusion between the adjoining

Sandra Citi; Helena Sabanay; Ross Jakes; Benjamin Geiger; John Kendrick-Jones

1988-01-01

410

Metal\\/insulator\\/metal junctions for electrochemical surface science  

Microsoft Academic Search

.  \\u000a We describe the preparation and characterization of Al-AlOx-Ag tunnel junctions and calculate the energy distribution of the tunneling hot electrons in the range 0–2.5 eV above the\\u000a Fermi level of silver. Because the mean free path of the hot electrons is of the order of the thickness of the silver film\\u000a of the junction, which is at the same time

Detlef Diesing; Guido Kritzler; Matthias Stermann; Dirk Nolting; Andreas Otto

2003-01-01

411

Reappraisal of the Arabia–India–Somalia triple junction kinematics  

Microsoft Academic Search

We propose alternative kinematics for the Arabia–India–Somalia triple junction based on a re-interpretation of seismological and magnetic data. The new triple junction of the ridge–ridge–ridge type is located at the bend of the Sheba Ridge in the eastern gulf of Aden at 14.5°N and 56.4°E. The Owen fracture zone (Arabia–India boundary) is connected to the Sheba Ridge by an ultra-slow

Marc Fournier; Philippe Patriat; Sylvie Leroy

2001-01-01

412

Raman Scattering at Plasmonic Junctions Shorted by Conductive Molecular Bridges  

SciTech Connect

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.

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

2013-04-10

413

The effect of stretching thiyl and ethynyl Au molecular junctions  

Microsoft Academic Search

We perform density functional theory (DFT) calculations of the stretching of Au(111)-X-Au(111) molecular junctions where X is either a thiyl or ethynyl biradical. The equilibrium geometries for the radicals adsorbing on the surface are first calculated and the radicals then placed in the junction geometry. The unit cell is stepwise increased in length and the geometry relaxed at each step.

R. C. Hoft; M. J. Ford; V. M. García-Suárez; C. J. Lambert; M. B. Cortie

2008-01-01

414

From Josephson junction metamaterials to tunable pseudo-cavities  

E-print Network

The scattering through a Josephson junction interrupting a superconducting line is revisited including power leakage. We discuss also how to make tunable and broadband resonant mirrors by concatenating junctions. As an application, we show how to construct cavities using these mirrors, thus connecting two research fields: JJ quantum metamaterials and coupled cavity arrays. We finish by discussing the first non-linear corrections to the scattering and their measurable effects.

D. Zueco; C. Fernández-Juez; J. Yago; U. Naether; B. Peropadre; J. J. García-Ripoll; J. J. Mazo

2013-05-21

415

Measurement of gap junctional communication by fluorescence activated cell sorting  

Microsoft Academic Search

Summary  Cell-to-cell communication via gap junctions has played a fundamental role in the orderly development of multicellular organisms.\\u000a Current methods for measuring this function apply mostly to homotypic cell populations. The newly introduced Fluorescence\\u000a Activated Cell Sorting (FACS) method, albeit with some limitations, is simple, reliable, and quantitative in measuring the\\u000a dye transfer via gap junctions in both homotypic and heterotypic

David T. Kiang; Rahn Kollander; H. Helen Lin; Sigrid LaVilla; Michael M. Atkinson

1994-01-01

416

Effect of sequence on the conformation of DNA holliday junctions.  

PubMed

Structures of the DNA sequences d(CCGGCGCCGG) and d(CCAGTACbr(5)UGG) are presented here as four-way Holliday junctions in their compact stacked-X forms, with antiparallel alignment of the DNA strands. Thus, the ACC-trinucleotide motif, previously identified as important for stabilizing the junction, is now extended to PuCPy, where Pu is either an adenine or guanine, and Py is either a cytosine, 5-methylcytosine, or 5-bromouracil but not thymine nucleotide. We see that both sequence and base substituents affect the geometry of the junction in terms of the interduplex angle as well as the previously defined conformational variables, J(roll) (the rotation of the stacked duplexes about their respective helical axis) and J(slide) (the translational displacement of the stacked duplexes along their respective helical axis). The structures of the GCC and parent ACC containing junctions fall into a distinct conformational class that is relatively undistorted in terms of J(slide) and J(roll), with interduplex angles of 40-43 degrees. The substituted ACbr(5)U structure, however, is more akin to that of the distorted methylated ACm(5)C containing junction, with J(slide) (>or=2.3 A) and a similar J(roll) (164 degrees) opening the major groove-side of the junction, but shows a reduced interduplex angle. In contrast, the analogous d(CCAGTACTGG) sequence has to date been crystallized only as resolved B-DNA duplexes. This suggests that there is an electronic effect of substituents at the pyrimidine Py position on the stability of four-stranded junctions. The single-crystal structures presented here, therefore, show how sequence affects the detailed geometry, and subsequently, the associated stability and conformational dynamics of the Holliday junction. PMID:12911300

Hays, Franklin A; Vargason, Jeffrey M; Ho, P Shing

2003-08-19

417

Hot phonon controlled-junction superconducting quantum interference device  

Microsoft Academic Search

The optimal design of a direct current superconducting quantum interference device (DC-SQUID) with high sensitivity requires two identical Josephson junctions, which is difficult to achieve. The design of a DC-SQUID using controlled Josephson junction technology provides a mechanism for modifying the characteristics of the device. Here we report on the nano-fabrication and measurement of a DC-SQUID utilizing two Dayem bridge

G. D. Hutchinson; H. Qin; D. J. Kang; S. B. Lee; D. G. Hasko; M. G. Blamire; D. A. Williams

2003-01-01

418

Enumerating the junction trees of a decomposable graph  

PubMed Central

We derive methods for enumerating the distinct junction tree representations for any given decomposable graph. We discuss the relevance of the method to estimating conditional independence graphs of graphical models and give an algorithm that, given a junction tree, will generate uniformly at random a tree from the set of those that represent the same graph. Programs implementing these methods are included as supplemental material. PMID:20981245

Thomas, Alun; Green, Peter J

2010-01-01

419

Improved GaAs solar cells with very thin junctions  

NASA Technical Reports Server (NTRS)

Violet cells with 500-1000 A junction depths have been made in GaAs by narrow junction diffusion followed by anodization. The best AM0 efficiencies obtained by this technique have been 10.5% (14% at AM1). GaAlAs-GaAs structures with very thin GaAlAs layers are much more promising, and efficiencies of over 18% at AM0 have been measured (21.9% at AM1).

Hovel, H. J.; Woodall, J. M.

1976-01-01

420

Prism-coupled light emission from tunnel junctions  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

421

Magnesium-diboride ramp-type Josephson junctions  

Microsoft Academic Search

Josephson junctions have been realized in which two superconducting magnesium-diboride (MgB2) layers are separated by a thin MgO barrier layer, using the ramp-type configuration. Their current-voltage characteristics follow the behavior described by the resistively shunted junction model, with an excess current of about 30% of the critical current Ic. A suppression of 70% of Ic was achieved in applied magnetic

Dragana Mijatovic; Alexander Brinkman; Ingrid Oomen; Guus Rijnders; Hans Hilgenkamp; Horst Rogalla; Dave H. A. Blank

2002-01-01

422

Planar Josephson junctions fabricated with magnesium diboride films  

Microsoft Academic Search

Josephson junctions were fabricated in three planar configurations using a focused ion beam (FIB) to cut ?70 nm gaps in MgB2 bridges. In two of the approaches - narrowed microbridges where a 0.1 ?m bridge was left in place after the FIB cut or thinned microbridges where a 20-40 nm-thick film layer remained uncut - we reproduced junction results obtained

D. A. Kahler; J. Talvacchio; J. M. Murduck; A. Kirschenbaum; R. E. Brooks; S. B. Bu; J. Choi; D. M. Kim; C.-B. Eom

2003-01-01

423

Transient photovoltaic phenomena of ITO\\/Si junctions  

Microsoft Academic Search

Photovoltaic decay (PVD) data were obtained from poly-Si\\/ITO junctions and compared to data from single crystal poly-Si\\/ITO junctions. Both cells featured p-type poly-Si for the upper layer. Short light pulses were pumped into the upper layer while measurements were made with an FET probe. The sampling time interval was varied from 100 nsec to several orders of magnitude slower in

Z. Harzion; M. Zafrir; J. Rishpon; M. Evenor; N. Croitoru

1985-01-01

424

Etching Magnetic Tunnel Junction with Metal Etchers  

NASA Astrophysics Data System (ADS)

Etch performances of inductory-coupled plasma (ICP) metal etchers with several gas systems are examined under constant ion energy condition to evaluate extendibility to the 300 mm wafer magnetic tunnel junction (MTJ) etch process. The ICP-Ar sputter etch affects little on magnetic properties, and shows about the same magnetoresistive (MR) ratio with conventional Ar ion milling. Major issue is the electrical short by redeposition. The etch uniformity over the wafer and precise etch end-point detection are important. The Cl2 addition to the ICP-Ar etch plasma shows serious pattern deformation and degradation of loop offset (Hoff). Methanol (Me-OH) etch shows slightly lower MR-ratio due to material degradation. However, better Hoff is observed probably due to the ion protection effect by thin carbon layer over the etched surface. Dilution of Me-OH with Ar improves MR ratio. Ar/Me-OH and ICP-Ar etch processes would be the candidate for 300 mm process at present.

Kinoshita, Keizo; Utsumi, Hiroaki; Suemitsu, Katsumi; Hada, Hiromitsu; Sugibayashi, Tadahiko

2010-08-01

425

Tunneling anisotropic magnetoresistance in Ni break junctions  

NASA Astrophysics Data System (ADS)

Anisotropic magnetoresistance (AMR) is the difference in resistance as the magnetization direction is changed with respect to the direction of current flow. We will present results of first-principles calculations of AMR in Ni nanowires. It is known that in the ballistic regime the conductance of a magnetic nanowire changes in steps of e^2/h as the angle of the magnetization changes with respect to the axis of the wire.[1] This ballistic AMR (BAMR) effect originates from the spin-orbit coupling which can change the number of bands crossing the Fermi energy ( EF ) as the magnetization direction is changed. We extend this consideration to the case of a break junction, where transport occurs via tunneling. We find a significant dependence of the tunneling conductance on the magnetization direction, an effect known as tunneling AMR (TAMR). We find that states localized at the electrode tips near the break are broadened by the spin-orbit interaction and contribute significantly to the tunneling. The position with respect to EF and broadening of these states depend strongly on the orientation of magnetization. Our results bear a striking resemblance to recent experimental results [2], clearly indicating an origin different from the one proposed previously.[2] This work is supported by Seagate Research and Nebraska NSF-MRSEC. [1] J. Velev et al. PRL 94, 127203 (2005), [2] K. Bolotin et al. PRL 97, 127202 (2006).

Burton, J. D.; Tsymbal, E. Y.; Mryasov, O. N.

2007-03-01

426

Charge transport in single photochromic molecular junctions  

NASA Astrophysics Data System (ADS)

Recently, photoswitchable molecules, i.e. diarylethene, gained significant interest due to their applicability in data storage media, as optical switches, and in novel logic circuits [1]. Diarylethene-derivative molecules are the most promising candidates to design electronic functional elements, because of their excellent thermal stability, high fatigue resistance, and negligible change upon switching [1]. Here, we present the preferential conductance of specifically designed sulfur-free diarylethene molecules [2] bridging the mechanically controlled break-junctions at low temperatures [3]. The molecular energy levels and electrode couplings are obtained by evaluating the current-voltage characteristics using the single-level model [4]. The charge transport mechanism of different types of diarylethene molecules is investigated, and the results are discussed within the framework of novel theoretical predictions. [4pt] [1] M. Del Valle etal., Nat Nanotechnol 2, 176 (2007) S. J. van der Molen etal., Nano. Lett. 9, 76 (2009).[0pt] [2] D. Sysoiev etal., Chem. Eur. J. 17, 6663 (2011).[0pt] [3] Y. Kim etal., Phys. Rev. Lett. 106, 196804 (2011).[0pt] [4] Y. Kim etal., Nano Lett. 11, 3734 (2011). L. Zotti etal., Small 6, 1529 (2010).

Kim, Youngsang; Pietsch, T.; Scheer, Elke; Hellmuth, T.; Pauly, F.; Sysoiev, D.; Huhn, T.; Exner, T.; Groth, U.; Steiner, U.; Erbe, A.

2012-02-01

427

Ouabain modulates epithelial cell tight junction  

PubMed Central

Epithelial cells treated with high concentrations of ouabain (e.g., 1 ?M) retrieve molecules involved in cell contacts from the plasma membrane and detach from one another and their substrates. On the basis of this observation, we suggested that ouabain might also modulate cell contacts at low, nontoxic levels (10 or 50 nM). To test this possibility, we analyzed its effect on a particular type of cell–cell contact: the tight junction (TJ). We demonstrate that at concentrations that neither inhibit K+ pumping nor disturb the K+ balance of the cell, ouabain modulates the degree of sealing of the TJ as measured by transepithelial electrical resistance (TER) and the flux of neutral 3 kDa dextran (JDEX). This modulation is accompanied by changes in the levels and distribution patterns of claudins 1, 2, and 4. Interestingly, changes in TER, JDEX, and claudins behavior are mediated through signal pathways containing ERK1/2 and c-Src, which have distinct effects on each physiological parameter and claudin type. These observations support the theory that at low concentrations, ouabain acts as a modulator of cell–cell contacts. PMID:20534449

Larre, Isabel; Lazaro, Amparo; Contreras, Ruben G.; Balda, Maria S.; Matter, Karl; Flores-Maldonado, Catalina; Ponce, Arturo; Flores-Benitez, David; Rincon-Heredia, Ruth; Padilla-Benavides, Teresita; Castillo, Aida; Shoshani, Liora; Cereijido, Marcelino

2010-01-01

428

Ferroelectric tunnel junctions with graphene electrodes.  

PubMed

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

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