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1

Novel methods for low resistance ultra-shallow junction formation  

NASA Astrophysics Data System (ADS)

Source Drain parasitic resistance is expected to become one of the major roadblocks to the continued improvements of device performance. Going by the ITRS roadmap, the source drain parasitic resistance is expected to become as much as 26% of the intrinsic device resistance by the 45 nm technology node. As the active concentration in current junctions is approaching the electrical solubility limits, it is unlikely that the current method of junction formation will be able to provide the low resistance junctions required for future technology nodes. It is clear that new annealing techniques that yield active concentrations well above the solubility limit are needed to allow continued scaling of MOS devices. In the first half of my thesis, I will present a new method to obtain B active concentrations above the electrical solubility limits. We show that the boron activation obtained after SPER increases with the temperature at which the regrowth is carried out. Further, by carrying out the regrowth at a high temperature it is possible to obtain active concentrations as high 6.5 x 1020/cm3---which is well above the solubility limits of B in silicon. Subsequent anneals that reduce the leakage current without significant deactivation or diffusion are presented. Finally, we observed that the active B is stable through back end thermal budgets. Pulsed laser annealing is another technique that can give active concentrations well above the solubility limits. The main drawback to junction formation using this method is that light interacts with the patterned surface resulting in (among other effects) the melting and deforming of the poly gate the S/D regions melt. The latter part of my thesis presents a new technique that uses selective absorption to selectively melt the source drain regions without melting the poly gate. Possible solutions to other issues are also discussed. With the increased importance of SiGe as the source-drain material, we also study the stability of various dopants activated using pulsed laser annealing as a function of the germanium fraction.

Jain, Sameer H.

2005-07-01

2

Exploring the limits of N-type ultra-shallow junction formation.  

PubMed

Low resistivity, near-surface doping in silicon represents a formidable challenge for both the microelectronics industry and future quantum electronic devices. Here we employ an ultra-high vacuum strategy to create highly abrupt doping profiles in silicon, which we characterize in situ using a four point probe scanning tunnelling microscope. Using a small molecule gaseous dopant source (PH3) which densely packs on a reconstructed silicon surface, followed by encapsulation in epitaxial silicon, we form highly conductive dopant sheets with subnanometer control of the depth profiles. This approach allows us to test the limits of ultra-shallow junction formation, with room temperature resistivities of 780 ?/? at an encapsulation depth of 4.3 nm, increasing to 23 k?/? at an encapsulation depth of only 0.5 nm. We show that this depth-dependent resistivity can be accounted for by a combination of dopant segregation and surface scattering. PMID:23721101

Polley, Craig M; Clarke, Warrick R; Miwa, Jill A; Scappucci, Giordano; Wells, Justin W; Jaeger, David L; Bischof, Maia R; Reidy, Richard F; Gorman, Brian P; Simmons, Michelle

2013-06-25

3

Depth profile characterization of ultra shallow junction implants.  

PubMed

A need for analysis techniques, complementary to secondary ion mass spectrometry (SIMS), for depth profiling dopants in silicon for ultra shallow junction (USJ) applications in CMOS technologies has recently emerged following the difficulties SIMS is facing there. Grazing incidence X-ray fluorescence (GIXRF) analysis in the soft X-ray range is a high-potential tool for this purpose. It provides excellent conditions for the excitation of the B-K and the As-L(iii,ii) shells. The X-ray standing wave (XSW) field associated with GIXRF on flat samples is used here as a tunable sensor to obtain information about the implantation profile because the in-depth changes of the XSW intensity are dependent on the angle of incidence. This technique is very sensitive to near-surface layers and is therefore well suited for the analysis of USJ distributions. Si wafers implanted with either arsenic or boron at different fluences and implantation energies were used to compare SIMS with synchrotron radiation-induced GIXRF analysis. GIXRF measurements were carried out at the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the electron storage ring BESSY II using monochromatized undulator radiation of well-known radiant power and spectral purity. The use of an absolutely calibrated energy-dispersive detector for the acquisition of the B-Kalpha and As-Lalpha fluorescence radiation enabled the absolute determination of the total retained dose. The concentration profile was obtained by ab initio calculation and comparison with the angular measurements of the X-ray fluorescence. PMID:19941133

Hönicke, Philipp; Beckhoff, Burkhard; Kolbe, Michael; Giubertoni, Damiano; van den Berg, Jaap; Pepponi, Giancarlo

2010-04-01

4

Junction Photovoltge (JPV) Techniques for Ultra-Shallow Junction Characterization  

E-print Network

dependent, non-steady-state surface photo-voltage (SPV) theory for oxidized silicon wafers was developed photovoltage (JPV) theory for abrupt box like doping profiles pn junctions and derived steady state analytical equations describing JPV distribution inside and outside of illumination area. A two-dimensional, non-steady-state

Schroder, Dieter K.

5

Selective Solid-Phase Epitaxy of Ultra-Shallow p+ Aluminum-Doped Silicon Junctions  

E-print Network

). The grown material is highly p+ -doped with aluminum. The abruptness of the doping transition has beenSelective Solid-Phase Epitaxy of Ultra-Shallow p+ Aluminum-Doped Silicon Junctions for Integration and Materials, DIMES, Delft University of Technology, Feldmannweg 17, 2628 CT Delft, The Netherlands. 2 Kavli

Technische Universiteit Delft

6

Down to 2 nm Ultra Shallow Junctions : Fabrication by IBS Plasma Immersion Ion Implantation Prototype PULSION registered  

SciTech Connect

Classical beam line implantation is limited in low energies and cannot achieve P+/N junctions requirements for <45nm node. Compared to conventional beam line ion implantation, limited to a minimum of about 200 eV, the efficiency of Plasma Immersion Ion Implantation (PIII) is no more to prove for the realization of Ultra Shallow Junctions (USJ) in semiconductor applications: this technique allows to get ultimate shallow profiles (as implanted) thanks to no lower limitation of energy and offers high dose rate. In the field of the European consortium NANOCMOS, Ultra Shallow Junctions implanted on a semi-industrial PIII prototype (PULSION registered ) designed by the French company IBS, have been studied. Ultra shallow junctions implanted with BF3 at acceleration voltages down to 20V were realized. Contamination level, homogeneity and depth profile are studied. The SIMS profiles obtained show the capability to make ultra shallow profiles (as implanted) down to 2nm.

Torregrosa, Frank; Etienne, Hasnaa; Mathieu, Gilles; Roux, Laurent [ION BEAM SERVICES, ZI Peynier-Rousset, rue Gaston Imbert Prolongee, 13790 Peynier (France)

2006-11-13

7

Carrier Density Profiling of Ultra-Shallow Junction Layers Through Corrected C-V Plotting  

SciTech Connect

The aim of this report is to present and justify a new approach for carrier density profiling in ultra-shallow junction (USJ) layer. This new approach is based on a capacitance measurement model, which takes series impedance, shunt resistance and the presence of a boron skin on the USJ layer into account. It allows us to extract the depletion layer capacitances in the USJ layer from C-V plotting more accurately and hence to obtain better carrier density profiles. Based on this new approach the carrier density profiles of different USJ layers with and without halo-style implants are obtained and discussed.

Chen, James; Dimitrov, Dimitar; Dimitrova, Tatiana [Four Dimensions, Inc., 3140 Diablo Ave, Hayward, California, 94545 (United States); Timans, Paul [Mattson Technology, Inc. Fremont, California (United States); Gelpey, Jeff; McCoy, Steve [Mattson Technology Canada, Inc., Vancouver (Canada); Lerch, Wilfried; Paul, Silke [Mattson Thermal Products GmbH, Dornstadt (Germany); Bolze, Detlef [IHP, Frankfurt (Oder) (Germany)

2008-11-03

8

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

9

Process advances to achieve ultra-shallow junctions for 0.10 ?m technology requirements  

NASA Astrophysics Data System (ADS)

Ion implants of 11B+, 49BF2+, 31P+ and 75As+ at energies as low as 0.25 keV at various doses were implanted and rapid thermal annealed (RTA) with controlled O2 levels in N2 ambient to investigate the effects of oxygen during anneal. For each of these implant species, an optimal RTA ambient of O2 in N2 is established which maximizes retained dose and uniformity while minimizing oxidation enhanced diffusion (OED) and other oxygen related diffusion effects. TEM analysis was performed for all species and energy thresholds identified (at 1e15/cm2), below which no extended-defects or loops were observed to form and hence a regime where transient enhanced diffusion (TED) should not affect dopant diffusion. In this energy regime with anneals in a low ppm O2 in N2 ambient, the contributions from TED, OED, BED (boridation enhanced diffusion or other dopant enhanced diffusion effects) are minimized/eliminated. With these enhanced diffusion mechanisms under control, the effects of minimizing the thermal diffusion by controlled "slow" and "fast" spike anneals (<0.1s) are investigated. Taking advantage of these various processing techniques, source/drain extension requirements to satisfy the National Technology Roadmap (NTRS) requirements at the 0.10 ?m node are satisfied for the p-extension by both B (0.25 to 0.5 keV) and BF2 (1.1 to 2.2 keV). In addition, n-extension requirements are meet for As+ (1.0 to 2.0 keV), and P+ (1.0 to 5.0 keV) for contact junctions are reviewed for the NTRS requirements at 0.10?m geometries.

Bertuch, Adam F.; Zhao, Zhiyong; Downey, Daniel F.; Falk, Scott W.

1999-06-01

10

Fabrication of Ultra-Shallow Junctions on 300 mm Wafers Using the Plasma Immersion Implanter PULSION registered Followed by Spike Annealing Using LEVITOR Furnace  

SciTech Connect

Thanks to the European Project SEA-NET, an industrial version of the IBS Plasma Ion Implantation tool has been installed in LETI for the fabrication of Ultra-Shallow Junction for 45 and 32 nm CMOS on 200 and 300 mm wafers. In this study, we present first doping results on 300 mm wafers using BF{sub 3} plasma. Annealing after PULSION implantation is performed by the ASM furnace LEVITOR. This tool, which works on conduction heating is emissivity independent for temperature control and allows reaching high ramp up and ramp down speeds (up to 900 deg. C/s). Main characteristics of as implanted wafers are presented (metal contamination 2E10/cm{sup 2}, SIMS depth profiles down to 5 nm). Then the effect of convection gas in the annealing process on sheet resistance, junction depth and uniformity is presented.

Torregrosa, Frank; Etienne, Hasnaa; Sempere, Guillaume; Mathieu, Gilles; Roux, Laurent [ION BEAM SERVICES, ZI Peynier-Rousset, rue Gaston Imbert Prolongee, 13790 Peynier (France); Milesi, Frederic; Gonzatti, Frederic [CEA LETI-MINATEC, DRT/DPTS/SDOT, 17 rue des Martyrs 38054 Grenoble cedex 9 (France); Pages, Xavier [ASM Europe B. V., Versterkerstraat 8, 1322 AP Almere (Netherlands)

2008-11-03

11

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

12

A Deep Level Transient Spectroscopy Study on Recrystallization of Ultra-Shallow Implanted Silicon  

NASA Astrophysics Data System (ADS)

Defect formation and annihilation in ultra-shallow junctions (USJs) during an annealing process is characterized by deep level transient spectroscopy (DLTS). A difference in the recovery of implantation damage was clearly identified between samples with and without pre-amorphization-implantation (PAI). DLTS depth profiles reveal that the defects are formed at the region ten-times deeper than implanted depth. The photoluminescence (PL) intensity probing of the region having defects distinctly correlates to the quantity of defects detected by DLTS.

Okutani, Masashi; Takashima, Shuhei; Yoshimoto, Masahiro; Yoo, Woo Sik

2011-01-01

13

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

14

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

15

Ultra-shallow box-like profiles fabricated by pulsed UV-laser doping process  

SciTech Connect

Ultra-shallow, box-like impurity profiles are produced using Gas Immersion Laser Doping (GILD) and then analyzed by spreading resistance profilometry (SRP) and secondary ion mass spectrometry (SIMS) to determine the impurity distribution. At high concentrations, the profiles obtained by SRP exhibit the expected box-like shape over the entire range of junction depths: The measured concentration within the junction region is uniform while the dopant gradient at the junction exceeds 0.5 decades/nm. In comparison, the same profiles analyzed by SIMS show a broader transition at the metallurgical junction. Caused by knock-ons and ion mixing during the sputtering process, this inaccuracy is reduced, but not eliminated by lowering the acceleration energy of the primary Cs{sup +} ion beam. At lower concentrations (< 10{sup 19}/cm{sup 3}), profiles analyzed by SRP exhibit shallower junctions than expected. Electrical measurements of diodes and Hall structures show that high-quality, ultra-shallow n{sup +}p, np and pn are fabricated with good dose control using GILD. For complete characterization of GILD, accurate measurement of both chemical and electrically-active dopant profiles are required. At present, neither SIMS nor SRP provides an entirely accurate impurity profile.

Ishida, E.; Sigmon, T.W. [Stanford Univ., CA (United States); Weiner, K.H. [Lawrence Livermore National Lab., CA (United States)

1993-03-23

16

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

17

Ultra-Shallow Imaging Using 2D & 3D Seismic Reflection Methods  

E-print Network

The research presented in this dissertation focuses on the survey design, acquisition, processing, and interpretation of ultra-shallow seismic reflection (USR) data in two and three dimensions. The application of 3D USR ...

Sloan, Steven D.

2008-01-01

18

PLAsma Doping For P+ Junction Formation In 90 nm NOR Flash Memory Technology  

SciTech Connect

For MOS devices belonging to 65 nm technology node and beyond, ultra-shallow LDD junctions are needed in order to match requirements in terms of sheet resistance and doping profile. PLAsma Doping has been proposed and developed as an effective and viable technology capable to produce such junctions, while keeping high productivity. Furthermore, as the equipment is simpler and smaller than a common implanter, PLAsma Doping can be considered, from the cost of ownership point of view, an attractive solution also for those applications whose requirements are not so demanding; an example can be the junctions of a Flash Memory. Aim of this study is to evaluate, electrically, the compatibility of PLAsma Doping with a NOR Flash Memory belonging to 90 nm technology node. Results of PLAsma Doping experiment concerning the matching of the device parameters will be here presented. Further investigation is needed in order to exclude any possible effect on device reliability.

Bigarella, Dario; Soncini, Valter [STMicroelectronics srl, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Raj, Deven; Singh, Vikram; Walther, Steve [VSEA Varian Semiconductor Equipment Associates, 35 Dory Road, Gloucester, MA 01930-2297 (United States)

2006-11-13

19

Schottky Barrier Height Modulation by Ultra-Shallow Low-Dose Dopant Diffusion  

E-print Network

Schottky Barrier Height Modulation by Ultra-Shallow Low-Dose Dopant Diffusion Milos Popadi*, Lis K damage that could lead to transient enhanced diffusion of the dopants. Depending on the substrate type. The back of the wafer was metallized and is a diode terminal. Structures for sheet resistance measurements

Technische Universiteit Delft

20

Characteristics of pulsed plasma doping sources for ultrashallow junction formation  

E-print Network

Characteristics of pulsed plasma doping sources for ultrashallow junction formation Ankur Agarwala ultrashallow junctions. In plasma doping, ions are extracted from a quasicontinuous plasma using a pulsed bias-based techniques have been proposed for fabricating USJs, including pulsed plasma implantation PPI .11 PPI

Kushner, Mark

21

PULSION registered: A Versatile 200 to 300 mm Bridge Tool Plasma Immersion Ion Implanter for Ultra-Shallow Doping and Nanotechology Applications  

SciTech Connect

Thanks to the European Projects SEA-NET and PULLNANO, an industrial version of the IBS Plasma Ion Implantation tool has been installed in LETI for the fabrication of Ultra-Shallow Junctions for 45 and 32 nm CMOS on 200 and 300 mm wafers. In this paper, we present the main machine characteristics (layout, contamination, homogeneity, reproducibility, uptime) and we show that implanted wafers are compatible with the 32 nm nodes requirements. Then doping results (sheet resistance vs junction depth and leakage current) using several annealing technics are presented (laser, flash and spike anneals). In the second part of the paper, versatility of the tool is demonstrated with its use for other applications (3D doping, hydrogenation, solar cells...)

Torregrosa, Frank; Etienne, Hasnaa; Sempere, Guillaume; Mathieu, Gilles; Roux, Laurent [Ion Beam Services, ZI Peynier-Rousset, rue Gaston Imbert Prolongee, 13790 Peynier (France); Milesi, Frederic; Gonzatti, Frederic [CEA LETI-MINATEC, DRT/DPTS/SDOT, 17 rue des Martyrs 38054 Grenoble cedex 9 (France)

2008-11-03

22

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

23

Dose Measurements of Ultra-Shallow Implanted As and B in Si by RBS and ERD  

SciTech Connect

Continuous miniaturization of integrated circuits requires narrower dopant profile depth in the Si channel and consequently the use of ultra-shallow implants in the manufacturing process. Secondary Ion Mass Spectroscopy (SIMS) is routinely used to measure the boron depth concentration profiles. However, due to the altered nature of the near-surface sputtering process inherent to SIMS, it underestimates the B implanted doses for implantation energies below 2 keV. Alternate ion beam methods for absolute dose measurements of ultra-shallow implanted As and B in Si are presented in this study. The dopant implant energies ranged from 250 eV, to 5 keV for boron and from 500 eV to 5 keV for arsenic. Implanted doses for both B and As varied from 2 x 1013 to 1 x 1015 atoms/cm2. The arsenic implants were studied with Rutherford Backscattering Spectrometry (RBS) using 2 MeV carbon ions. The absolute arsenic implanted doses were measured to an accuracy of better than 5%. The 1 keV arsenic implants were extensively studied for radiation damage with a 12C beam. No appreciable arsenic dose loss was observed during C irradiation for an integrated charge of {<=} 80 {mu}C, which was the maximum used for these studies. For the B implants, Elastic Recoil Detection (ERD) was used with 14 MeV F4+ ions. A 9.4 {mu}m Mylar foil was found to adequately stop the scattered 19F ions and give good energy separation for the 11B recoiled ions. The absolute dose measurements are {approx} 5% for the 5 keV 11B implants. Significant radiation damage was observed for the ultra shallow implants and the measured B dose has been obtained by extrapolation to the zero integrated charge of the beam. The absolute boron dose measurements of the ultra shallow (250 eV) implants were determined with an accuracy better than 10%.

Pelicon, P. [Ion Beam Modification and Analysis Laboratory, Dept. of Physics, University of North Texas, Denton, TX 76203-1427 (United States); Institute 'Jozef Stefan' , P.O.B. 3000, SI-1001 Ljubljana (Slovenia); Ravi Prasad, G.V. [Ion Beam Modification and Analysis Laboratory, Dept. of Physics, University of North Texas, Denton, TX 76203-1427 (United States); Institute of Physics, Bhubaneswar-751005, Orissa (India); El Bouanani, M. [Laboratory for Electronic Materials and Devices, Dept. of Materials Science, University of North Texas, Denton, TX 76203-5310 (United States); Guo, B.N. [Varian Semiconductor Equipment Associates, Inc., 35 Dory Road, Gloucester, MA 01923 (United States); Birt, D.; Duggan, J.L.; McDaniel, F.D. [Ion Beam Modification and Analysis Laboratory, Dept. of Physics, University of North Texas, Denton, TX 76203-1427 (United States)

2003-08-26

24

Rapid thermal processing, an integral part of shallow junction formation  

NASA Astrophysics Data System (ADS)

Rapid thermal processing (RTP) has become one of the important processing tools for shallow junction formation in ultralarge scale integration (ULSI). However, its application must be integrated with the choice of ion, energy and dose of the ion implantation to optimize and balance the conflicting requirements of minimum dopant penetration and minimum defect formation. The preamorphization of silicon which is widely used to eliminate channeling can lead to end-of-range dislocation formation and it strongly modulates the enhanced diffusion of boron. Preamorphization by silicon — a light ion — implantation leads to a high density of end-of-range dislocations but it can eliminate the enhanced boron diffusion under certain conditions. End-of-range defects are shown to cause junction leakage. Preamorphization by heavy ions results in fewer defects but its effect on boron diffusion is still being worked out. Both the formation of defects and the enhancement of the boron diffusion are due to excess silicon interstitials originating in the ion implant damage. The two most powerful tools to reduce excess interstitials are the use of heavy ions implanted at low energies and the use of RTP for annealing.

Sedgwick, T. O.

1989-02-01

25

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

26

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

27

Plasminogen activator inhibitor-1 regulates myoendothelial junction formation  

PubMed Central

Rationale Plasminogen activator inhibitor-1 (PAI-1) is a biomarker for several vascular disease states; however, its target of action within the vessel wall is undefined. Objective Determine the ability of PAI-1 to regulate myoendothelial junction (MEJ) formation. Methods and Results Myoendothelial junctions are found throughout the vasculature linking endothelial cells (EC) and vascular smooth muscle cells (VSMC). Using a vascular cell co-culture (VCCC) we isolated MEJ fractions and performed two-dimensional differential gel electrophoresis. Mass spectrometry identified PAI-1 as being enriched within MEJ fractions, which we confirmed in vivo. In the VCCC, recombinant PAI-1 (rPAI-1) added to the EC monolayer significantly increased MEJs. Conversely, addition of a PAI-1 monoclonal antibody to the EC monolayer reduced the number of MEJs. This was also observed in vivo where mice fed a high fat diet had increased PAI-1 and MEJs and the number of MEJs in coronary arterioles of PAI-1?/? mice was significantly reduced when compared to C57Bl/6 mice. The presence of MEJs in PAI-1?/? coronary arterioles was restored when their hearts were transplanted into and exposed to the circulation of C57Bl/6 mice. Application of biotin-conjugated PAI-1 to the EC monolayer in vitro confirmed the ability of luminal PAI-1 to translocate to the MEJ. Functionally, phenylephrine-induced heterocellular calcium communication in the VCCC was temporally enhanced when rPAI-1 was present, and prolonged when PAI-1 was absent. Conclusion Our data implicate circulating PAI-1 as a key regulator of MEJ formation and a potential target for pharmacological intervention in diseases with vascular abnormalities (e.g., diabetes mellitus). PMID:20133900

Heberlein, Katherine; Straub, Adam C.; Best, Angela K.; Greyson, Mark A.; Looft-Wilson, Robin C.; Sharma, Poonam R.; Meher, Akshaya; Leitinger, Norbert; Isakson, Brant E

2010-01-01

28

Benefits of Damage Engineering for PMOS Junction Stability  

SciTech Connect

As CMOS devices continue to shrink, the formation of ultra shallow junction (USJ) in the source/drain extension remains to be a key challenge requiring high dopant activation, shallow dopant profile and abrupt junctions. The next generations of sub nano-CMOS devices impose a new set of challenges such as elimination of residual defects resulting in higher leakage, difficulty to control lateral diffusion, junction stability post anneal and junction formation in new materials. To address these challenges for advanced technological nodes beyond 32 nm, it is imperative to explore novel species and techniques. Molecular species such as Carborane (C{sub 2}B{sub 10}H{sub 12}), a novel doping species and a promising alternative to monomer Boron is of considerable interest due to the performance boost for 22 nm low power and high performance devices. Also, to reduce residual defects, damage engineering methodologies have generated a lot of attention as it has demonstrated significant benefits in device performance. Varian proprietary techniques to perform implants at cold temperatures (PTC II) have demonstrated lower junction leakage, enhanced activation, reduced dopant diffusion and less dopant deactivation due to the reduction of self-interstitial atoms present at the end-of-range (EOR) with low implant temperatures. In this paper, for the first time, there is a comprehensive study of the effect of implant temperature on defect engineering affecting deactivation/reactivation, and it is well established in this paper that colder the implant temperature the better it is for damage engineering with reduced EOR defects and better amorphization. The effect has been studied over a wide range of implant temperature. To understand any difference in deactivation between molecular and monomer Boron and to provide direct comparison equivalent Boron implants, co-implanted with Carbon were also studied. Implants with wide range of temperatures are implemented using PTC II. This paper will also show how damage reduction correlates with optimum junction formation and stability.

Khaja, Fareen; Colombeau, Benjamin; Thanigaivelan, Thirumal; Ramappa, Deepak; Henry, Todd [Varian Semiconductor Equipment Associates, Inc. 35 Dory Road, Gloucester, MA 01930 (United States)

2011-01-07

29

Benefits of Damage Engineering for PMOS Junction Stability  

NASA Astrophysics Data System (ADS)

As CMOS devices continue to shrink, the formation of ultra shallow junction (USJ) in the source/drain extension remains to be a key challenge requiring high dopant activation, shallow dopant profile and abrupt junctions. The next generations of sub nano-CMOS devices impose a new set of challenges such as elimination of residual defects resulting in higher leakage, difficulty to control lateral diffusion, junction stability post anneal and junction formation in new materials. To address these challenges for advanced technological nodes beyond 32 nm, it is imperative to explore novel species and techniques. Molecular species such as Carborane (C2B10H12), a novel doping species and a promising alternative to monomer Boron is of considerable interest due to the performance boost for 22 nm low power and high performance devices. Also, to reduce residual defects, damage engineering methodologies have generated a lot of attention as it has demonstrated significant benefits in device performance. Varian proprietary techniques to perform implants at cold temperatures (PTC II) have demonstrated lower junction leakage, enhanced activation, reduced dopant diffusion and less dopant deactivation due to the reduction of self-interstitial atoms present at the end-of-range (EOR) with low implant temperatures. In this paper, for the first time, there is a comprehensive study of the effect of implant temperature on defect engineering affecting deactivation/reactivation, and it is well established in this paper that colder the implant temperature the better it is for damage engineering with reduced EOR defects and better amorphization. The effect has been studied over a wide range of implant temperature. To understand any difference in deactivation between molecular and monomer Boron and to provide direct comparison equivalent Boron implants, co-implanted with Carbon were also studied. Implants with wide range of temperatures are implemented using PTC II. This paper will also show how damage reduction correlates with optimum junction formation and stability.

Khaja, Fareen; Colombeau, Benjamin; Thanigaivelan, Thirumal; Ramappa, Deepak; Henry, Todd

2011-01-01

30

A new approach to photovoltaic junction formation by using pulse implantation doping technique  

E-print Network

in connection with the prospect of mass production of photovoltaic cells. For example, Muller et al. [1] have1353 A new approach to photovoltaic junction formation by using pulse implantation doping technique. 2014 The paper presents the first demonstration of a new method of forming photovoltaic p-n junction

Paris-Sud XI, Université de

31

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

32

Formin-mediated actin polymerization at endothelial junctions is required for vessel lumen formation and stabilization.  

PubMed

During blood vessel formation, endothelial cells (ECs) establish cell-cell junctions and rearrange to form multicellular tubes. Here, we show that during lumen formation, the actin nucleator and elongation factor, formin-like 3 (fmnl3), localizes to EC junctions, where filamentous actin (F-actin) cables assemble. Fluorescent actin reporters and fluorescence recovery after photobleaching experiments in zebrafish embryos identified a pool of dynamic F-actin with high turnover at EC junctions in vessels. Knockdown of fmnl3 expression, chemical inhibition of formin function, and expression of dominant-negative fmnl3 revealed that formin activity maintains a stable F-actin content at EC junctions by continual polymerization of F-actin cables. Reduced actin polymerization leads to destabilized endothelial junctions and consequently to failure in blood vessel lumenization and lumen instability. Our findings highlight the importance of formin activity in blood vessel morphogenesis. PMID:25584798

Phng, Li-Kun; Gebala, Véronique; Bentley, Katie; Philippides, Andrew; Wacker, Andrin; Mathivet, Thomas; Sauteur, Loïc; Stanchi, Fabio; Belting, Heinz-Georg; Affolter, Markus; Gerhardt, Holger

2015-01-12

33

Evaluation of the formation of a junctional DNA nanostructure through annealing curve analysis.  

PubMed

During the self-assembly of different numbers of oligonucleotides comprising junctional DNA nanostructures, a change in environmental variables (e.g., temperature or salt concentration) has a substantial influence on the final products. Further, distinctive annealing temperatures of oligonucleotides are observed depending on the state of hybridization. Here, we present an evaluation of the annealing characteristics of oligonucleotides for the formation of a simple junctional DNA nanostructure using an annealing curve analysis. This method may be useful for analyzing the formation of complex junctional DNA nanostructures. PMID:25597993

Shin, Seung Won; Park, Kyung Soo; Um, Soong Ho

2015-02-20

34

Composition and Formation of Intercellular Junctions in Epithelial Cells  

NSDL National Science Digital Library

The polarized nature of epithelial cells is manifested by the nonrandom partitioning of organelles within the cells, the concentration of intercellular junctions at one pole, and the asymmetric distribution of proteins and lipids within the plasma membrane. These features allow epithelia to fulfill their specific tasks, such as targeted uptake and secretion of molecules and the segregation of different tissue compartments. The accessibility ofDrosophila melanogaster and Caenorhabditis elegans to genetic and cell biological analyses, combined with the study of mammalian cells in culture, provides an ideal basis for understanding the mechanisms that control the establishment and maintenance of epithelial cell polarity and tissue integrity. Here, we focus on some of the best-studied junctions and membrane-associated protein complexes and their relation to cell polarity. Comparisons between fly, worm, and vertebrate epithelia reveal marked similarities with respect to the molecules used, and pronounced differences in the organization of the junctions themselves.

Elisabeth Knust (Heinrich-Heine Universität Düsseldorf; Institut für Genetik)

2002-12-06

35

Interaction between Pericytes and Endothelial Cells Leads to Formation of Tight Junction in Hyaloid Vessels  

PubMed Central

The hyaloid vessel is a transient vascular network that nourishes the lens and the primary vitreous in the early developmental periods. In hyaloid vessels devoid of the support of astrocytes, we demonstrate that tight junction proteins, zonula occludens-1 and occludin, are regularly expressed at the junction of endothelial cells. To figure out the factor influencing the formation of tight junctions in hyaloid vessels, we further progress to investigate the interactions between endothelial cells and pericytes, two representative constituent cells in hyaloid vessels. Interestingly, endothelial cells interact with pericytes in the early postnatal periods and the interaction between two cell types provokes the up-regulation of transforming growth factor ?1. Further in vitro experiments demonstrate that transforming growth factor ?1 induces the activation of Smad2 and Smad3 and the formation of tight junction proteins. Taken together, in hyaloid vessels, pericytes seem to regulate the formation of tight junctions by the interaction with endothelial cells even without the support of astrocytes. Additionally, we suggest that the hyaloid vessel is a valuable system that can be utilized for the investigation of cell-cell interaction in the formation of tight junctions in developing vasculatures. PMID:24213675

Jo, Dong Hyun; Kim, Jin Hyoung; Heo, Jong-Ik; Kim, Jeong Hun; Cho, Chung-Hyun

2013-01-01

36

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

37

Controllable p-n junction formation in monolayer graphene using electrostatic substrate engineering.  

PubMed

We investigate electric transport in graphene on SiO2 in the high field limit and report on the formation of p-n junctions. Previously, doping of graphene has been achieved by using multiple electrostatic gates, or charge transfer from adsorbants. Here we demonstrate a novel approach to create p-n junctions by changing the local electrostatic potential in the vicinity of one of the contacts without the use of extra gates. The approach is based on the electronic modification not of the graphene but of the substrate and produces a well-behaved, sharp junction whose position and height can be controlled. PMID:20886859

Chiu, Hsin-Ying; Perebeinos, Vasili; Lin, Yu-Ming; Avouris, Phaedon

2010-11-10

38

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

39

Infrared Semiconductor Laser Annealing Used for Formation of Shallow Junction  

Microsoft Academic Search

We report continuous-wave (CW) infrared-semiconductor laser annealing of silicon implanted with boron atoms with assistance of diamond-like carbon (DLC) films as optical absorption layer in order to form shallow junctions. Boron ions were implanted at 10 keV at concentrations 5x1014, 1x1015 and 2x1015 cm-2. Boron clusters were also implanted at 30 and 6 keV at 1x1015cm-2. The samples were coated

Toshiyuki Sameshima; Yuta Mizutani; Naoki Sano; Masao Naito

40

Assessment of Sphingosine-1-Phosphate Activity in Biological Samples by Receptor Internalization and Adherens Junction Formation  

PubMed Central

Sphingosine-1-phosphate (S1P) is a bioactive lipid mediator involved in many biological actions, including vascular homeostasis and immune cell trafficking. S1P activity is mediated by specific G protein-coupled receptors, leading to multiple physiological responses including adherens junction formation in endothelial cells. Here, we describe bioassays for rapidly assessing S1P activity in biological fluids based on ligand-induced receptor internalization in transfected HEK293 cells and consequent adherens junction formation of vascular endothelial cells. PMID:22528440

Obinata, Hideru; Hla, Timothy

2013-01-01

41

Effect of nitride sidewall spacer process on boron dose loss in ultrashallow junction formation  

E-print Network

Effect of nitride sidewall spacer process on boron dose loss in ultrashallow junction formation P nitride spacer process on the boron profile in silicon and the related dose loss of B from the Si; published 4 February 2004 A nitride spacer with an underlying deposited tetraethoxysilane oxide

Dunham, Scott

42

Fabrication of single linear aromatic molecular junction with high formation probability  

NASA Astrophysics Data System (ADS)

The fabrication of single molecular junctions (SMJs) with high formation probabilities and high conductance values is important to the progress of molecular electronics. The relationship between formation probability and the structure of a single molecular junction is not clear because of the lack of systematic studies. Here, we propose a guideline for the fabrication of SMJs with high formation probabilities, focusing on the nanogap and molecular sizes. The investigation of simple linear aromatic compounds, which consist of a small number of benzene rings (i.e., benzene, naphthalene, and anthracene), using Au, Ag, and Cu electrodes revealed that SMJs with high formation probabilities and high conductance values can be obtained when the molecular size is equivalent to or smaller than the nanogap size.

Liu, Chenyang; Kaneko, Satoshi; Komoto, Yuuki; Fujii, Shintaro; Kiguchi, Manabu

2014-10-01

43

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

44

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

NASA Astrophysics Data System (ADS)

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 the nMOSFET at the same supply voltage, 0.5 V. For a gate length of 20 nm, Ge tunnel transistors can provide similar speed in comparison to 45-nm-node nMOSFETs (18 nm gate length), but saves more than 2× in power and lowers energy by over 7×. Toward demonstrating these transistors, a process for forming submicron p +n + Ge tunnel junctions has been utilized in which Al-doped p + Ge is regrown on n + Ge, following melt-back of a patterned Al deposition. Transmission electron microscopy (TEM) reveals the regrown film and a contact microstructure consistent with the Al-Ge phase diagram. The low peak-to-valley current ratio (PVR) of devices produced by this growth method is likely a result of point defects or junction doping non-uniformity as TEM suggest no dislocations at the regrown junction. The PVR of these junctions does not improve as the device area is reduced from 100 to 0.1 ?m 2, a size smaller than the formation scale for grains in the Al-Ge system.

Zhang, Qin; Sutar, Surajit; Kosel, Thomas; Seabaugh, Alan

2009-01-01

45

IQGAP1 controls tight junction formation through differential regulation of claudin recruitment.  

PubMed

IQGAP1 is a scaffolding protein previously implicated in adherens junction formation. However, its role in the establishment or maintenance of tight junctions (TJs) has not been explored. We hypothesized that IQGAP1 could regulate TJ formation by modulating the expression and/or localization of junctional proteins, and we systematically tested this hypothesis in the model Madin-Darby canine kidney (MDCK) cell line. We find that IQGAP1 silencing enhances a transient increase in transepithelial electrical resistance (TER) observed during the early stages of TJ formation (Cereijido et al., 1978). Quantitative microscopy and biochemical experiments suggest that this effect of IQGAP1 on TJ assembly is accounted for by reduced expression and TJ recruitment of claudin 2, and increased TJ recruitment of claudin 4. Furthermore, we show that IQGAP1 also regulates TJ formation through its interactor CDC42, because IQGAP1 knockdown increases the activity of the CDC42 effector JNK and dominant-negative CDC42 prevents the increase in TER caused by IQGAP1 silencing. Hence, we provide evidence that IQGAP1 modulates TJ formation by a twofold mechanism: (1) controlling the expression and recruitment of claudin 2 and recruitment of claudin 4 to the TJ, and (2) transient inhibition of the CDC42-JNK pathway. PMID:25588839

Tanos, Barbara E; Perez Bay, Andres E; Salvarezza, Susana; Vivanco, Igor; Mellinghoff, Ingo; Osman, Mahasin; Sacks, David B; Rodriguez-Boulan, Enrique

2015-03-01

46

tal1 regulates the formation of intercellular junctions and the maintenance of identity in the endocardium  

PubMed Central

The endocardium forms the inner lining of the heart tube, where it enables blood flow and also interacts with the myocardium during the formation of valves and trabeculae. Although a number of studies have identified regulators of the morphogenesis of the myocardium, relatively little is known about the molecules that control endocardial morphogenesis. Prior work has implicated the bHLH transcription factor Tal1 in endocardial tube formation: in zebrafish embryos lacking Tal1, endocardial cells form a disorganized mass within the ventricle and do not populate the atrium. Through blastomere transplantation, we find that tal1 plays a cell-autonomous role in regulating endocardial extension, suggesting that Tal1 activity influences the behavior of individual endocardial cells. The defects in endocardial behavior in tal1-deficient embryos originate during the earliest steps of endocardial morphogenesis: tal1-deficient endocardial cells fail to generate a cohesive monolayer at the midline and instead pack tightly together into a multi-layered aggregate. Moreover, the tight junction protein ZO-1 is mislocalized in the tal1-deficient endocardium, indicating a defect in intercellular junction formation. In addition, we find that the tal1-deficient endocardium fails to maintain its identity; over time, a progressively increasing number of tal1-deficient endocardial cells initiate myocardial gene expression. However, the onset of defects in intercellular junction formation precedes the onset of ectopic myocardial gene expression in the tal1-deficient endocardium. We therefore propose a model in which Tal1 has distinct roles in regulating the formation of endocardial intercellular junctions and maintaining endocardial identity. PMID:24075907

Schumacher, Jennifer A.; Bloomekatz, Joshua; Garavito-Aguilar, Zayra V.; Yelon, Deborah

2014-01-01

47

tal1 Regulates the formation of intercellular junctions and the maintenance of identity in the endocardium.  

PubMed

The endocardium forms the inner lining of the heart tube, where it enables blood flow and also interacts with the myocardium during the formation of valves and trabeculae. Although a number of studies have identified regulators in the morphogenesis of the myocardium, relatively little is known about the molecules that control endocardial morphogenesis. Prior work has implicated the bHLH transcription factor Tal1 in endocardial tube formation: in zebrafish embryos lacking Tal1, endocardial cells form a disorganized mass within the ventricle and do not populate the atrium. Through blastomere transplantation, we find that tal1 plays a cell-autonomous role in regulating endocardial extension, suggesting that Tal1 activity influences the behavior of individual endocardial cells. The defects in endocardial behavior in tal1-deficient embryos originate during the earliest steps of endocardial morphogenesis: tal1-deficient endocardial cells fail to generate a cohesive monolayer at the midline and instead pack tightly together into a multi-layered aggregate. Moreover, the tight junction protein ZO-1 is mislocalized in the tal1-deficient endocardium, indicating a defect in intercellular junction formation. In addition, we find that the tal1-deficient endocardium fails to maintain its identity; over time, a progressively increasing number of tal1-deficient endocardial cells initiate myocardial gene expression. However, the onset of defects in intercellular junction formation precedes the onset of ectopic myocardial gene expression in the tal1-deficient endocardium. We therefore propose a model in which Tal1 has distinct roles in regulating the formation of endocardial intercellular junctions and maintaining endocardial identity. PMID:24075907

Schumacher, Jennifer A; Bloomekatz, Joshua; Garavito-Aguilar, Zayra V; Yelon, Deborah

2013-11-15

48

Formation of droplets and bubbles in a microfluidic T-junction--scaling and mechanism of break-up{  

E-print Network

Formation of droplets and bubbles in a microfluidic T-junction--scaling and mechanism of break-up in microfluidic T-junction geometries. At low capillary numbers break-up is not dominated by shear stresses: experimental results support the assertion that the dominant contribution to the dynamics of break-up arises

Prentiss, Mara

49

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

50

Study of silicon-germanium junction formation for SOI based CMOS technology  

Microsoft Academic Search

Si1-xGex source\\/drain technology has been sucessfully applied to bulk metal oxide semiconductor field effect transistors (MOSFETs). Both channel mobility and source\\/drain contact resistivity are substantially improved with this technology. In this dissertation, Si1-xGex junction formation for silicon on insulator (SOI) based CMOS technology was investigated. Strain in epitaxially grown films on SOI films and silicon nanowires is studied using Raman

Yan Du

2008-01-01

51

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

52

Droplet Formation in Microfluidic T-junction Generators Operating in the Transitional Regime  

NASA Astrophysics Data System (ADS)

This study focuses on the droplet generation at a microfluidic T-junction operating in the transition regime where the geometry of the intersection, the capillary number, the flow ratio and viscosity ratio of the two phases influence the droplet formation. We presented our experimental observations by tracking various parameters during the formation cycle such as the shape of the droplet, inter droplet 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. The observations allow a model to be developed to describe the formation process which incorporates a detailed geometric description of the drop shape combined with a force balance and necking criteria to define the droplet size, production rate and spacing. The model inherently captures the influence of the intersection geometry, including the channel width ratio and height/width ratio, Capillary number and flow ratio on the performance of the generator. The model is validated by comparing it to speed videos of the formation process for several T-junction geometries across a range of Capillary numbers and viscosity ratios. /newline /newline The authors acknowledge the Natural Science and Engineering Research Council of Canada, Canada Research Chair program, Canada Foundation for Innovation, and University of Waterloo for research grants to C.R. and research support to C.E.; Ontarios's Early Research Award to C.R.; the Canada Graduate Scholarship to T.G.; and Danny Chan's assistance with the CFD models.

Glawdel, Tomasz; Elbuken, Caglar; Ren, Carolyn

2013-03-01

53

Non-Contact and Non-Destructive Characterization of Shallow Implanted Silicon PN Junctions using Ultra-Violet Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Ultra-shallow boron implanted (B+ 1 keV 1×1015 cm-2) n-type Si wafers were prepared and characterized by four point probe, SIMS and 363.8 nm excited ultra-violet (UV) Raman spectroscopy before and after rapid thermal annealing (RTA). The penetration depth of 363.8 nm laser radiation in a backscattering Raman configuration, is approximately 5 nm. As junction depth increases from high temperature RTA, sheet resistance decreases. Raman peaks shift in the lower wavenumber direction and its full-width-at-half-maximum (FWHM) broadens. There is clear correlation between junction depth and Raman spectra data. UV Raman spectroscopy can be used as a very powerful non-contact, non-destructive, in-line characterization and monitoring technique for ultra-shallow junctions (USJs).

Fukumoto, Masashi; Hasuike, Noriyuki; Harima, Hiroshi; Yoshimoto, Masahiro; Yoo, Woo Sik

2011-01-01

54

Fabrication and Characterization of SUB0.25 Micrometer CMOS PN Junctions by Low Energy Gallium Ion Focused Ion Beam Implantation  

Microsoft Academic Search

The main thrust of this thesis is the investigation of a Focused Ion Beam (FIB)-based approach for fabricating p^+-n shallow junctions approaching the nanometer scale (15-50 nm) which will be compatible with future generation CMOS technology. Ultra shallow junctions are formed by directly implanting low energy (3-25 keV) Ga ions into a crystalline Si substrate using a FIB implanter. Secondary

Homyar Cavas Mogul

1994-01-01

55

The role of the cell adhesion molecule uvomorulin in the formation and maintenance of the epithelial junctional complex  

PubMed Central

The role of the epithelial adhesion molecule uvomorulin in the formation of the epithelial junctional complex in the Madin-Darby canine kidney (MDCK) cell line was investigated. Experiments were carried out to determine whether specific inhibition of uvomorulin function would interfere selectively with the formation, stability, or function of the apical zonula adherens (ZA) and zonula occludens (ZO), or whether it would interfere with all forms of intercellular contact including the desmosomes. The effects of blocking antibodies and Fab fragments to uvomorulin on the formation of the junctional complex was examined with a Ca2+ switch assay for de novo junction assembly. The formation of the ZO, the ZA, and the desmosomes was assayed by fluorescence staining with an antibody to the tight junction-specific protein ZO-1, with rhodamine-phalloidin for ZA-associated actin filaments, and with an anti-desmoplakin antibody, respectively. Under different conditions and times of antibody treatment the extent of inhibition of the formation of each of the junctional elements was very similar. The ability of the cells to eventually overcome the inhibitory effect of the antibodies and form junctions correlated with the reappearance of uvomorulin at the regions of cell-cell contact. Therefore uvomorulin seems to mediate an early adhesion event between epithelial cells that is a prerequisite for the assembly of all elements of the junctional complex. In contrast, the transepithelial electrical resistance of confluent, well-established monolayers of MDCK cells grown on filters was not greatly affected by treatment with the various antibodies or Fab fragments. A small transient decrease in resistance observed with the polyclonal alpha-uvomorulin IgG may be due to a more subtle modulation of the junctional complex. PMID:3049625

1988-01-01

56

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

57

Lattice Boltzmann simulations of bubble formation in a microfluidic T-junction.  

PubMed

A lattice Boltzmann equation method based on the Cahn-Hilliard diffuse interface theory is developed to investigate the bubble formation process in a microchannel with T-junction mixing geometry. The bubble formation process has different regimes, namely, squeezing, dripping and jetting regimes, which correspond to the primary forces acting on the system. Transition from regime to regime is generally dictated by the capillary number Ca, volumetric flow ratio Q and viscosity ratio ?. A systematic analysis is performed to evaluate these effects. The computations are performed in the range of 10(-4)

Amaya-Bower, Luz; Lee, Taehun

2011-06-28

58

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. PMID:25419468

Zhang, Jianying; Wang, James H-C

2014-01-01

59

MuSK Frizzled-Like Domain Is Critical for Mammalian Neuromuscular Junction Formation and Maintenance.  

PubMed

The muscle-specific kinase MuSK is one of the key molecules orchestrating neuromuscular junction (NMJ) formation. MuSK interacts with the Wnt morphogens, through its Frizzled-like domain (cysteine-rich domain [CRD]). Dysfunction of MuSK CRD in patients has been recently associated with the onset of myasthenia, common neuromuscular disorders mainly characterized by fatigable muscle weakness. However, the physiological role of Wnt-MuSK interaction in NMJ formation and function remains to be elucidated. Here, we demonstrate that the CRD deletion of MuSK in mice caused profound defects of both muscle prepatterning, the first step of NMJ formation, and synapse differentiation associated with a drastic deficit in AChR clusters and excessive growth of motor axons that bypass AChR clusters. Moreover, adult MuSK?CRD mice developed signs of congenital myasthenia, including severe NMJs dismantlement, muscle weakness, and fatigability. We also report, for the first time, the beneficial effects of lithium chloride, a reversible inhibitor of the glycogen synthase kinase-3, that rescued NMJ defects in MuSK?CRD mice and therefore constitutes a novel therapeutic reagent for the treatment of neuromuscular disorders linked to Wnt-MuSK signaling pathway deficiency. Together, our data reveal that MuSK CRD is critical for NMJ formation and plays an unsuspected role in NMJ maintenance in adulthood. PMID:25810523

Messéant, Julien; Dobbertin, Alexandre; Girard, Emmanuelle; Delers, Perrine; Manuel, Marin; Mangione, Francesca; Schmitt, Alain; Le Denmat, Dominique; Molgó, Jordi; Zytnicki, Daniel; Schaeffer, Laurent; Legay, Claire; Strochlic, Laure

2015-03-25

60

Mesenchymal stem cells with modification of junctional adhesion molecule a induce hair formation.  

PubMed

The junctional adhesion molecule A (JAM-A) has been shown to serve a crucial role in the proliferation, differentiation, and tube-like formation of epithelial cells during angiogenesis. The role of JAM-A in hair follicle (HF) regeneration has not yet been reported. In this study, we used human JAM-A-modified human mesenchymal stem cells (MSCs) to repair HF abnormalities in BALB/c nu/nu mice. The JAM-A gene and JAM-A short hairpin RNA were transfected into cultured human MSCs to generate the JAM-A overexpression MSCs (JAM-A(ov) MSCs) and JAM-A knockdown MSCs (JAM-A(kd) MSCs), respectively. These cells were injected intradermally into the skin of nude mice during the first telogen phase of the HF that occurs 21 days postnatally. We found that JAM-A(ov) MSCs migrated into the HF sheath and remodeled HF structure effectively. The HF abnormalities such as HF curve and HF zigzag were remodeled, and hair formation was improved 7 days following injection in both the JAM-A(ov) MSC and MSC groups, compared with the JAM-A(kd) MSC group or negative control group. Furthermore, the JAM-A(ov) MSC group showed enhanced hair formation in contrast to the MSC group, and the number of curved and zigzagged HFs was reduced by 80% (p < .05). These results indicated that JAM-A(ov) MSCs improved hair formation in nude mice through HF structure remodeling. PMID:24558164

Wu, Minjuan; Guo, Xiaocan; Yang, Ling; Wang, Yue; Tang, Ying; Yang, Yongji; Liu, Houqi

2014-04-01

61

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

62

A case of cervicomedullary junction tanycytic ependymoma associated with marked cyst formation.  

PubMed

Tanycytic ependymomas are a subtype of ependymomas that were formally recognized as a new pathological entity in the latest World Health Organization (WHO) classification of 2000. They occur mostly in the spinal cord. Only a few reports have analyzed the proliferative potentials of these tumors; however, it has been reported that the MIB-1 labeling index of tanycytic ependymoma is lower than that of other subtypes of WHO grade II ependymomas. We report a rare case of cervicomedullary junction tanycytic ependymoma associated with marked cyst formation. A 62-year-old man had a history of progressive gait disturbance, diplopia, and swallowing disturbance over a one-month period prior to admission. Magnetic resonance imaging (MRI) showed a cystic mass with a mural nodule at the cervicomedullary junction with Gd-DTPA enhancement. Cyst-subarachnoid shunt was performed using a far lateral approach. After 6 years, however, the man was readmitted to the hospital because of reaccumulation of the cyst. Partial removal of a mural nodule and a cyst-subarachnoid shunt were performed simultaneously by a midline suboccipital approach. The pathological diagnosis was tanycytic ependymoma. Postoperatively, the patient recovered well and was discharged from the hospital without further treatment. Most of the tumor cells had small, round nuclei; pleomorphism was minimal. The cytoplasm was dilated. The tumor cells were positive for EMA and s-100, and negative for CD-34. GFAP was not determined due to difficulty caused by background glial processes. The MIB-1 labeling index was less than 1%. Ultrastructurally, the tumor cells had ependymal cell features, such as desmosomes and microvilli. Based on these findings, the pathological diagnosis was tanycytic ependymoma. PMID:18095101

Ito, Tamio; Ozaki, Yoshimaru; Nakagawara, Jyoji; Nakamura, Hirohiko; Tanaka, Shinya; Nagashima, Kazuo

2005-01-01

63

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

64

Rho1 regulates adherens junction remodeling by promoting recycling endosome formation through activation of myosin II  

PubMed Central

Once adherens junctions (AJs) are formed between polarized epithelial cells they must be maintained because AJs are constantly remodeled in dynamic epithelia. AJ maintenance involves endocytosis and subsequent recycling of E-cadherin to a precise location along the basolateral membrane. In the Drosophila pupal eye epithelium, Rho1 GTPase regulates AJ remodeling through Drosophila E-cadherin (DE-cadherin) endocytosis by limiting Cdc42/Par6/aPKC complex activity. We demonstrate that Rho1 also influences AJ remodeling by regulating the formation of DE-cadherin–containing, Rab11-positive recycling endosomes in Drosophila postmitotic pupal eye epithelia. This effect of Rho1 is mediated through Rok-dependent, but not MLCK-dependent, stimulation of myosin II activity yet independent of its effects upon actin remodeling. Both Rho1 and pMLC localize on endosomal vesicles, suggesting that Rho1 might regulate the formation of recycling endosomes through localized myosin II activation. This work identifies spatially distinct functions for Rho1 in the regulation of DE-cadherin–containing vesicular trafficking during AJ remodeling in live epithelia. PMID:25079692

Yashiro, Hanako; Loza, Andrew J.; Skeath, James B.; Longmore, Gregory D.

2014-01-01

65

Vitamin D3 Regulates the Formation and Degradation of Gap Junctions in Androgen-Responsive Human Prostate Cancer Cells  

PubMed Central

1?-25(OH)2 vitamin D3 (1-25D), an active hormonal form of Vitamin D3, is a well-known chemopreventive and pro-differentiating agent. It has been shown to inhibit the growth of several prostate cancer cell lines. Gap junctions, formed of proteins called connexins (Cx), are ensembles of cell-cell channels, which permit the exchange of small growth regulatory molecules between adjoining cells. Cell-cell communication mediated by gap junctional channels is an important homeostatic control mechanism for regulating cell growth and differentiation. We have investigated the effect of 1-25D on the formation and degradation of gap junctions in an androgen-responsive prostate cancer cell line, LNCaP, which expresses retrovirally-introduced Cx32. Connexin32 is expressed by the luminal and well-differentiated cells of normal prostate and prostate tumors. Our results document that 1-25D enhances the expression of Cx32 and its subsequent assembly into gap junctions. Our results further show that 1-25D prevents androgen-regulated degradation of Cx32, post-translationally, independent of androgen receptor (AR)-mediated signaling. Finally, our findings document that formation of gap junctions sensitizes Cx32-expressing LNCaP cells to the growth inhibitory effects of 1-25D and alters their morphology. These findings suggest that the growth-inhibitory effects of 1-25D in LNCaP cells may be related to its ability to modulate the assembly of Cx32 into gap junctions. PMID:25188420

Kelsey, Linda; Katoch, Parul; Ray, Anuttoma; Mitra, Shalini; Chakraborty, Souvik; Lin, Ming-Fong; Mehta, Parmender P.

2014-01-01

66

Formation of shallow p+-n junctions using boron-nitride solid diffusion source  

Microsoft Academic Search

Shallow p+-n junctions on the order of 0.1-µm deep have been fabricated using boron-nitride (BN) solid diffusion sources. The process combines the hydrogen-injection method and rapid thermal processing (RTP). Sheet resistivities, in ranges from 50 to 130 ?\\/sq with junction depths from 0.1 to 0.19 µm, are possible in this technique. Diode characteristics of 0.11-µm junctions show low reverse leakage

Kyeong-Tae Kim; Choong-Ki Kim

1987-01-01

67

Cluster-formation in the Rosette molecular cloud at the junctions of filaments  

NASA Astrophysics Data System (ADS)

Aims: For many years feedback processes generated by OB-stars in molecular clouds, including expanding ionization fronts, stellar winds, or UV-radiation, have been proposed to trigger subsequent star formation. However, hydrodynamic models including radiation and gravity show that UV-illumination has little or no impact on the global dynamical evolution of the cloud. Instead, gravitational collapse of filaments and/or merging of filamentary structures can lead to building up dense high-mass star-forming clumps. However, the overall density structure of the cloud has a large influence on this process, and requires a better understanding. Methods: The Rosette molecular cloud, irradiated by the NGC 2244 cluster, is a template region for triggered star-formation, and we investigated its spatial and density structure by applying a curvelet analysis, a filament-tracing algorithm (DisPerSE), and probability density functions (PDFs) on Herschel column density maps, obtained within the HOBYS key program. Results: The analysis reveals not only the filamentary structure of the cloud but also that all known infrared clusters except one lie at junctions of filaments, as predicted by turbulence simulations. The PDFs of sub-regions in the cloud show systematic differences. The two UV-exposed regions have a double-peaked PDF we interprete as caused by shock compression, while the PDFs of the center and other cloud parts are more complex, partly with a power-law tail. A deviation of the log-normal PDF form occurs at AV ? 9m for the center, and around 4m for the other regions. Only the part of the cloud farthest from the Rosette nebula shows a log-normal PDF. Conclusions: The deviations of the PDF from the log-normal shape typically associated with low- and high-mass star-forming regions at AV ? 3-4m and 8-10m, respectively, are found here within the very same cloud. This shows that there is no fundamental difference in the density structure of low- and high-mass star-forming regions. We conclude that star-formation in Rosette - and probably in high-mass star-forming clouds in general - is not globally triggered by the impact of UV-radiation. Moreover, star formation takes place in filaments that arose from the primordial turbulent structure built up during the formation of the cloud. Clusters form at filament mergers, but star formation can be locally induced in the direct interaction zone between an expanding H II-region and the molecular cloud. Figures 4-6 and Appendices A-C are available in electronic form at http://www.aanda.org

Schneider, N.; Csengeri, T.; Hennemann, M.; Motte, F.; Didelon, P.; Federrath, C.; Bontemps, S.; Di Francesco, J.; Arzoumanian, D.; Minier, V.; André, Ph.; Hill, T.; Zavagno, A.; Nguyen-Luong, Q.; Attard, M.; Bernard, J.-Ph.; Elia, D.; Fallscheer, C.; Griffin, M.; Kirk, J.; Klessen, R.; Könyves, V.; Martin, P.; Men'shchikov, A.; Palmeirim, P.; Peretto, N.; Pestalozzi, M.; Russeil, D.; Sadavoy, S.; Sousbie, T.; Testi, L.; Tremblin, P.; Ward-Thompson, D.; White, G.

2012-04-01

68

Tight junction protein ZO-2 expression and relative function of ZO-1 and ZO-2 during mouse blastocyst formation  

SciTech Connect

Apicolateral tight junctions (TJs) between epithelial cells are multiprotein complexes regulating membrane polarity and paracellular transport and also contribute to signalling pathways affecting cell proliferation and gene expression. ZO-2 and other ZO family members form a sub-membranous scaffold for binding TJ constituents. We investigated ZO-2 contribution to TJ biogenesis and function during trophectoderm epithelium differentiation in mouse preimplantation embryos. Our data indicate that ZO-2 is expressed from maternal and embryonic genomes with maternal ZO-2 protein associated with nuclei in zygotes and particularly early cleavage stages. Embryonic ZO-2 assembled at outer blastomere apicolateral junctional sites from the late 16-cell stage. Junctional ZO-2 first co-localised with E-cadherin in a transient complex comprising adherens junction and TJ constituents before segregating to TJs after their separation from the blastocyst stage (32-cell onwards). ZO-2 siRNA microinjection into zygotes or 2-cell embryos resulted in specific knockdown of ZO-2 mRNA and protein within blastocysts. Embryos lacking ZO-2 protein at trophectoderm TJs exhibited delayed blastocoel cavity formation but underwent normal cell proliferation and outgrowth morphogenesis. Quantitative analysis of trophectoderm TJs in ZO-2-deficient embryos revealed increased assembly of ZO-1 but not occludin, indicating ZO protein redundancy as a compensatory mechanism contributing to the mild phenotype observed. In contrast, ZO-1 knockdown, or combined ZO-1 and ZO-2 knockdown, generated a more severe inhibition of blastocoel formation indicating distinct roles for ZO proteins in blastocyst morphogenesis.

Sheth, Bhavwanti; Nowak, Rachael L.; Anderson, Rebecca; Kwong, Wing Yee; Papenbrock, Thomas [School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX (United Kingdom); Fleming, Tom P. [School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX (United Kingdom)], E-mail: tpf@soton.ac.uk

2008-11-01

69

The MAGUK Protein MPP7 Binds to the Polarity Protein hDlg1 and Facilitates Epithelial Tight Junction Formation  

PubMed Central

Three groups of evolutionarily conserved proteins have been implicated in the establishment of epithelial cell polarity: the apically-localized proteins of the Par (Par3-Par6-aPKC-Cdc42) and Crumbs groups (Crb3-PALS1-PATJ) and the basolaterally localized proteins of the Dlg group (Dlg1-Scribble-Lgl). During epithelial morphogenesis, these proteins participate in a complex network of interdependent interactions that define the position and functional organization of adherens junctions and tight junctions. However, the biochemical pathways through which they control polarity are poorly understood. In this study, we identify an interaction between endogenous hDlg1 and MPP7, a previously uncharacterized MAGUK-p55 subfamily member. We find that MPP7 targets to the lateral surface of epithelial cells via its L27N domain, through an interaction with hDlg1. Loss of either hDlg1 or MPP7 from epithelial Caco-2 cells results in a significant defect in the assembly and maintenance of functional tight junctions. We conclude that the formation of a complex between hDlg1 and MPP7 promotes epithelial cell polarity and tight junction formation. PMID:17332497

Stucke, Volker M.; Timmerman, Evy; Vandekerckhove, Joel; Gevaert, Kris

2007-01-01

70

Formation of Satellite and subsatellite droplets in a flow-focusing junction for viscoelastic fluids  

NASA Astrophysics Data System (ADS)

The formation of a cascade of satellite and subsatellite oil droplets is observed in a flow-focusing microfluidic junction (250 micrometer of characteristic length) in the presence of surfactant (Sodium Dodecyl Sulfate), and polymer (100 to 1000 ppm of PAAm of high molecular mass). The size and distribution of the satellite and subsatellite droplets is quite reproducible. One and only one satellite droplet is formed in the dripping regime in case of Newtonian fluids [1]. When PAAm is added to the solution, the viscosity becomes viscoelastic and satellite droplets are many. The mechanism of breakup leading to multiple satellite droplets is self-repeating, as observed in previous work [2, 3]. At low frequency, the number of satellite droplet can go up to 7 or more. The distribution is generally very structured: a unique mother satellite droplet is surrounded by two daughter droplets, each of these daughter droplet is surrounded again by two grand-daughter droplets so that there are 4 daughter droplets in total. The ratio in volume between each generation is about 30. [1] Funfschilling D., Debas H., Li H.-Z.and Mason T. G., 2009, Phys. Rev. E, 80, 015301 [2] Muzzio F. J., Tjahjadi M. and Ottino J. M. 1991, Phys. Rev. Lett. 67, 54-57 [3] Tjahjadi M., Stone H. A. and Ottino J. M. 1992, J. Fluid Mech. 243, 297-317

Funfschilling, Denis; Carrier, Odile; Li, Huai-Zhi

2011-11-01

71

RhoA Mediates Cyclooxygenase2 Signaling to Disrupt the Formation of Adherens Junctions and Increase Cell Motility  

Microsoft Academic Search

Cyclooxygenase-2 (COX-2) represents an important target for treatment and prevention of colorectal cancer. Although COX-2 signaling is implicated in promoting tumor cell growth and invasion, the molecular mechanisms that mediate these processes are largely unknown. In this study, we show that the RhoA pathway mediates COX-2 signaling to disrupt the formation of adherens junctions and increase cell motility. Disruption of

Yu-Wen E. Chang; Jerry W. Marlin; Terry W. Chance; Rolf Jakobi

2006-01-01

72

Cooperativity between trans and cis interactions in cadherin-mediated junction formation  

E-print Network

to represent the first step in this signaling cascade. The interplay between trans binding and lateral ("cis to form junctions, consists of five tandem extracellular (EC) domains with immunoglobulin-like topology

Ben-Shaul, Avinoam

73

Study of silicon-germanium junction formation for SOI based CMOS technology  

NASA Astrophysics Data System (ADS)

Si1-xGex source/drain technology has been sucessfully applied to bulk metal oxide semiconductor field effect transistors (MOSFETs). Both channel mobility and source/drain contact resistivity are substantially improved with this technology. In this dissertation, Si1-xGex junction formation for silicon on insulator (SOI) based CMOS technology was investigated. Strain in epitaxially grown films on SOI films and silicon nanowires is studied using Raman spectroscopy and transmission electron microscope (TEM). For epitaxially grown Si1-xGe x film on SOI, there is lower degree of strain development in the SOI layer due to the rigid interface between the SOI and the burried oxide as compared to bulk. However, for silicon nanowires on oxide, the situation is different since nanowires serve as compliant substrates. Part of the strain energy is transferred to silicon nanowires. The consistency between synthesized Raman peak shifts and the experimental measurements verified the strain sharing between the epitaxially grown Si1-xGe x films and the silicon nanowires. Splittings of high order Laue zone line (HOLZ) from a convergent beam electron diffraction (CBED) pattern was quantified to study the strain distribution in epitaxial Si1- xGex films grown on silicon nanowires. It was found out in this study that elastic deformation of epitaxial Si 1-xGex at free surfaces leads to strain relaxation at these surfaces. This phenomenon is detrimental to strain engineering in a nanowire MOSFET and provides new challenges to develop smart designs for constraining strain in the nano-structures. Moreover, atomic layer deposition (ALD) Platinum is proposed for metal deposition on 3D epitaxial Si1-xGex source/drain. The uniform deposition around 3D Si1- xGex films effectively increases the contact surface area which is highly desired in the FinFET application.

Du, Yan

74

LSR/angulin-1 is a tricellular tight junction protein involved in blood-brain barrier formation.  

PubMed

The blood-brain barrier (BBB) is a term used to describe the unique properties of central nervous system (CNS) blood vessels. One important BBB property is the formation of a paracellular barrier made by tight junctions (TJs) between CNS endothelial cells (ECs). Here, we show that Lipolysis-stimulated lipoprotein receptor (LSR), a component of paracellular junctions at points in which three cell membranes meet, is greatly enriched in CNS ECs compared with ECs in other nonneural tissues. We demonstrate that LSR is specifically expressed at tricellular junctions and that its expression correlates with the onset of BBB formation during embryogenesis. We further demonstrate that the BBB does not seal during embryogenesis in Lsr knockout mice with a leakage to small molecules. Finally, in mouse models in which BBB was disrupted, including an experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis and a middle cerebral artery occlusion (MCAO) model of stroke, LSR was down-regulated, linking loss of LSR and pathological BBB leakage. PMID:25753034

Sohet, Fabien; Lin, Christina; Munji, Roeben N; Lee, Seo Yeon; Ruderisch, Nadine; Soung, Allison; Arnold, Thomas D; Derugin, Nikita; Vexler, Zinaida S; Yen, Frances T; Daneman, Richard

2015-03-16

75

Buried p-n junction formation in CuGaSe2 thin-film solar cells  

NASA Astrophysics Data System (ADS)

CuGaSe2/CdS interfaces and the mechanism behind the hetero p-n junction formation were investigated using solar cell devices which demonstrated about a 10% energy conversion efficiency. It was found that the CuGaSe2/CdS interface could be described as a CuGaSe2/Cu-deficient Cu-Ga-Se layer (CDL)/CdS structure and the p-n junction was located at the CuGaSe2/CDL interface that was present 50-100 nm from the CDL/CdS interface. While the difficulty of the realization of equilibrium n-type CuGaSe2 has been generally recognized, this result suggests that CDL consisting of ordered vacancy compound phases such as CuGa3Se5 can play the role of an n-type material.

Ishizuka, Shogo; Yamada, Akimasa; Fons, Paul J.; Kamikawa-Shimizu, Yukiko; Komaki, Hironori; Shibata, Hajime; Niki, Shigeru

2014-01-01

76

Gap junctions composed of connexins 41.8 and 39.4 are essential for colour pattern formation in zebrafish  

PubMed Central

Interactions between all three pigment cell types are required to form the stripe pattern of adult zebrafish (Danio rerio), but their molecular nature is poorly understood. Mutations in leopard (leo), encoding Connexin 41.8 (Cx41.8), a gap junction subunit, cause a phenotypic series of spotted patterns. A new dominant allele, leotK3, leads to a complete loss of the pattern, suggesting a dominant negative impact on another component of gap junctions. In a genetic screen, we identified this component as Cx39.4 (luchs). Loss-of-function alleles demonstrate that luchs is required for stripe formation in zebrafish; however, the fins are almost not affected. Double mutants and chimeras, which show that leo and luchs are only required in xanthophores and melanophores, but not in iridophores, suggest that both connexins form heteromeric gap junctions. The phenotypes indicate that these promote homotypic interactions between melanophores and xanthophores, respectively, and those cells instruct the patterning of the iridophores. DOI: http://dx.doi.org/10.7554/eLife.05125.001 PMID:25535837

Irion, Uwe; Frohnhöfer, Hans Georg; Krauss, Jana; Çolak Champollion, Tu?ba; Maischein, Hans-Martin; Geiger-Rudolph, Silke; Weiler, Christian; Nüsslein-Volhard, Christiane

2014-01-01

77

Gap junctions composed of connexins 41.8 and 39.4 are essential for colour pattern formation in zebrafish.  

PubMed

Interactions between all three pigment cell types are required to form the stripe pattern of adult zebrafish (Danio rerio), but their molecular nature is poorly understood. Mutations in leopard (leo), encoding Connexin 41.8 (Cx41.8), a gap junction subunit, cause a phenotypic series of spotted patterns. A new dominant allele, leo(tK3), leads to a complete loss of the pattern, suggesting a dominant negative impact on another component of gap junctions. In a genetic screen, we identified this component as Cx39.4 (luchs). Loss-of-function alleles demonstrate that luchs is required for stripe formation in zebrafish; however, the fins are almost not affected. Double mutants and chimeras, which show that leo and luchs are only required in xanthophores and melanophores, but not in iridophores, suggest that both connexins form heteromeric gap junctions. The phenotypes indicate that these promote homotypic interactions between melanophores and xanthophores, respectively, and those cells instruct the patterning of the iridophores. PMID:25535837

Irion, Uwe; Frohnhöfer, Hans Georg; Krauss, Jana; Çolak Champollion, Tu?ba; Maischein, Hans-Martin; Geiger-Rudolph, Silke; Weiler, Christian; Nüsslein-Volhard, Christiane

2014-01-01

78

Reliable Formation of Single Molecule Junctions with Air-Stable Diphenylphosphine Linkers  

SciTech Connect

We measure the conductance of single Au-molecule-Au junctions with a series of air-stable diphenylphosphine-terminated molecules using the scanning tunneling microscope-based break junction technique. Thousands of conductance versus displacement traces collected for each molecule are used to statistically analyze junction conductance and evolution upon elongation. Measured conductances for a series of alkane-based molecules exhibit an exponential decrease with increasing length, as expected for saturated molecules, with a tunneling decay constant of 0.98 {+-} 0.04. Measurements of junction elongation indicate strong metal-molecule binding, with a length that increases with the number of methylene groups in the backbone. Measured conductance histograms for four molecules with short, unsaturated backbones (e.g., benzene) are much broader with less well-defined peaks. These measurements are supported by density function theory calculations. The phosphine binds selectively to under-coordinated gold atoms through a donor-acceptor bond with a binding energy of about 1 eV. The calculated tunnel coupling correlates very well with experiment.

Parameswaran, R.; Hybertsen, M.; Widawsky, J.R.; Vázquez H.; Park, Y.S.; Boardman, B.M.; Nuckolls, C.; Steigerwald, M.L.; Venkataraman, L.

2010-07-15

79

Formation of three-particle clusters in hetero-junctions and MOSFET structures  

E-print Network

A novel interaction mechanism in MOSFET structures and $GaAs/AlGaAs$ hetero-junctions between the zone electrons of the two-dimensional (2D) gas and the charged traps on the insulator side is considered. By applying a canonical transformation, off-diagonal terms in the Hamiltonian due to the trapped level subsystem are excluded. This yields an effective three-particle attractive interaction as well as a pairing interaction inside the 2D electronic band. A type of Bethe- Goldstone equation for three particles is studied to clarify the character of the binding and the energy of the three-particle bound states. The results are used to offer a possible explanation of the Metal-Insulator transition recently observed in MOSFET and hetero-junctions.

E. P. Nakhmedov; K. Morawetz

2004-03-05

80

Junction formation of Cu(3)BiS(3) investigated by Kelvin probe force microscopy and surface photovoltage measurements.  

PubMed

Recently, the compound semiconductor Cu(3)BiS(3) 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 Cu(3)BiS(3) absorber layer and the junction formation with CdS, ZnS and In(2)S(3) 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 In(2)S(3) compared to that of CdS and ZnS. For In(2)S(3) and CdS buffer layers the KPFM experiments indicate negatively charged Cu(3)BiS(3) 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 In(2)S(3) buffer layer. Our findings indicate that Cu(3)BiS(3) 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; Sadewasser, Sascha

2012-01-01

81

Measurement of Single-Molecule Resistance by Repeated Formation of Molecular Junctions  

Microsoft Academic Search

The conductance of a single molecule connected to two gold electrodes was determined by repeatedly forming thousands of gold-molecule-gold junctions. Conductance histograms revealed well-defined peaks at integer multiples of a fundamental conductance value, which was used to identify the conductance of a single molecule. The resistances near zero bias were 10.5 +\\/- 0.5, 51 +\\/- 5, 630 +\\/- 50, and

Bingqian Xu; Nongjian J. Tao

2003-01-01

82

Dlg3 trafficking and apical tight junction formation is regulated by nedd4 and nedd4-2 e3 ubiquitin ligases.  

PubMed

The Drosophila Discs large (Dlg) scaffolding protein acts as a tumor suppressor regulating basolateral epithelial polarity and proliferation. In mammals, four Dlg homologs have been identified; however, their functions in cell polarity remain poorly understood. Here, we demonstrate that the X-linked mental retardation gene product Dlg3 contributes to apical-basal polarity and epithelial junction formation in mouse organizer tissues, as well as to planar cell polarity in the inner ear. We purified complexes associated with Dlg3 in polarized epithelial cells, including proteins regulating directed trafficking and tight junction formation. Remarkably, of the four Dlg family members, Dlg3 exerts a distinct function by recruiting the ubiquitin ligases Nedd4 and Nedd4-2 through its PPxY motifs. We found that these interactions are required for Dlg3 monoubiquitination, apical membrane recruitment, and tight junction consolidation. Our findings reveal an unexpected evolutionary diversification of the vertebrate Dlg family in basolateral epithelium formation. PMID:21920314

Van Campenhout, Claude A; Eitelhuber, Andrea; Gloeckner, Christian J; Giallonardo, Patrizia; Gegg, Moritz; Oller, Heide; Grant, Seth G N; Krappmann, Daniel; Ueffing, Marius; Lickert, Heiko

2011-09-13

83

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

84

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

PubMed

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 F(1)F(O)-ATP synthase (F(1)F(O)) supercomplexes. Overexpression of Fcj1 leads to increased CJ formation, branching of cristae, enlargement of CJ diameter, and reduced levels of F(1)F(O) supercomplexes. Impairment of F(1)F(O) 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 F(1)F(O) 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; Körner, Christian; Jagasia, Ravi; Keil, Thomas; Baumeister, Wolfgang; Cyrklaff, Marek; Neupert, Walter; Reichert, Andreas S

2009-06-15

85

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; Körner, Christian; Jagasia, Ravi; Keil, Thomas; Baumeister, Wolfgang; Cyrklaff, Marek; Neupert, Walter

2009-01-01

86

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

E-print Network

the myosin light chain kinase-calmodulin complex. This enzyme complex phosphorylates myosin light chains permitting actin-myosin interaction culminating in myometrial contraction. The balance between alpha- and beta-adrenergic receptor activation... of gap junctions in 48 hr organ culture. Page 15 23 3. Presence of gap junctions in response to E28 priming or cAIIP/CSK-altering agent controls. 4. Number of gap junctions in the circular layer of myometrium . 5. Number of gap junctions...

Gaddy, Dana

1985-01-01

87

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

88

Formation of functional gap junctions in amniotic fluid-derived stem cells induced by transmembrane co-culture with neonatal rat cardiomyocytes  

PubMed Central

Amniotic fluid-derived stem cells (AFSC) have been reported to differentiate into cardiomyocyte-like cells and form gap junctions when directly mixed and cultured with neonatal rat ventricular myocytes (NRVM). This study investigated whether or not culture of AFSC on the opposite side of a Transwell membrane from NRVM, allowing for contact and communication without confounding factors such as cell fusion, could direct cardiac differentiation and enhance gap junction formation. Results were compared to shared media (Transwell), conditioned media and monoculture media controls. After a 2-week culture period, AFSC did not express cardiac myosin heavy chain or troponin T in any co-culture group. Protein expression of cardiac calsequestrin 2 was up-regulated in direct transmembrane co-cultures and media control cultures compared to the other experimental groups, but all groups were up-regulated compared with undifferentiated AFSC cultures. Gap junction communication, assessed with a scrape-loading dye transfer assay, was significantly increased in direct transmembrane co-cultures compared to all other conditions. Gap junction communication corresponded with increased connexin 43 gene expression and decreased phosphorylation of connexin 43. Our results suggest that direct transmembrane co-culture does not induce cardiomyocyte differentiation of AFSC, though calsequestrin expression is increased. However, direct transmembrane co-culture does enhance connexin-43-mediated gap junction communication between AFSC. PMID:23634988

Connell, Jennifer Petsche; Augustini, Emily; Moise, Kenneth J; Johnson, Anthony; Jacot, Jeffrey G

2013-01-01

89

The Receptor Tyrosine Kinase MuSK Is Required for Neuromuscular Junction Formation In Vivo  

Microsoft Academic Search

Formation of neuromuscular synapses requires a series of inductive interactions between growing motor axons and differentiating muscle cells, culminating in the precise juxtaposition of a highly specialized nerve terminal with a complex molecular structure on the postsynaptic muscle surface. The receptors and signaling pathways mediating these inductive interactions are not known. We have generated mice with a targeted disruption of

Thomas M DeChiara; David C Bowen; David M Valenzuela; Mary V Simmons; William T Poueymirou; Susan Thomas; Erika Kinetz; Debra L Compton; Eduardo Rojas; John S Park; Cynthia Smith; Peter S DiStefano; David J Glass; Steven J Burden; George D Yancopoulos

1996-01-01

90

Myosins in cell junctions  

PubMed Central

The development of cell-cell junctions was a fundamental step in metazoan evolution, and human health depends on the formation and function of cell junctions. Although it has long been known that actin and conventional myosin have important roles in cell junctions, research has begun to reveal the specific functions of the different forms of conventional myosin. Exciting new data also reveals that a growing number of unconventional myosins have important roles in cell junctions. Experiments showing that cell junctions act as mechanosensors have also provided new impetus to understand the functions of myosins and the forces they exert. In this review we will summarize recent developments on the roles of myosins in cell junctions. PMID:22954512

Liu, Katy C.; Cheney, Richard E.

2012-01-01

91

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

92

Junction Photovoltage Metrology and High Resolution Mapping of Ion Implants Electrically Isolated from the Wafer Surface  

NASA Astrophysics Data System (ADS)

Application of the Junction Photovoltage (JPV) method for metrology of ultra-shallow implant (USJ) has been well documented. In this paper we report the application of the JPV method to control implant processes which create an electrically active layer isolated from the surface. In such structures four point probe (4PP) metrology is unreliable or impossible. This paper presents results obtained using a Junction Photo-Voltage (JPV) method optimized for characterization of these two processes, CMOS: Implantation through a screen oxide followed by anneal and also MeV p-type high energy implantation into n-type doped substrate followed by an anneal. Taking errors and necessary corrections into account the JPV method allows accurate high resolution mapping of such structures without the need for an extra process step. Results obtained from the JPV measurements were correlated to destructive off-line analytical measurement tools.

Korsós, Ferenc; Kis-Szabo, Krisztian; Don, Eric; Pap, Aron; Pavelka, Tibor; Laviron, Cyrille; Pfeffer, Marcus

2008-11-01

93

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

94

Formation of hydrothermal deposits at Kings Triple Junction, northern Lau back-arc basin, SW Pacific: The geochemical perspectives  

NASA Astrophysics Data System (ADS)

An inactive hydrothermal field was discovered near Kings Triple Junction (KTJ) in northern Lau back-arc basin during 19th cruise of R/V Akademik Mstislav Keldysh in 1990. The field consisted of a large elongated basal platform 'the pedestal' with several 'small' chimneys on its periphery and one 'main mound' superposed over it. The surrounding region is carpeted with lava pillows having ferromanganese 'precipitate' as infillings. The adjoining second field consisted of small chimney like growths termed as 'Christmas Tree' Field. The basal pedestal, the peripheral chimneys and small 'Christmas Tree' like growths (samples collected by MIR submersibles), though parts of the same hydrothermal field, differ significantly in their mineralogy and elemental composition indicating different history of formation. The pedestal slab consisting of chalcopyrite and pyrite as major minerals and rich in Cu is likely to have formed at higher temperatures than sphalerite dominated peripheral chimney. Extremely low concentration of high field strength elements (e.g. Zr, Hf, Nb and Ta) and enrichment of light REE in these sulfides indicate prominent influence of aqueous arc-magma, rich in subduction components. The oxide growths in the 'Christmas Tree' Field have two distinct layers, Fe rich orange-red basal part which seems to have formed at very low temperature as precipitates from diffused hydrothermal flows from the seafloor whereas Mn rich black surface coating is formed from hydrothermal fluids emanated from the seafloor during another episode of hydrothermal activity. Perhaps this is for the first time such unique hydrothermal oxide growths are being reported in association with hydrothermal system. Here, we discuss the possible processes responsible for the formation of these different hydrothermal deposits based on their mineralogy and geochemistry.

Paropkari, Anil L.; Ray, Durbar; Balaram, V.; Surya Prakash, L.; Mirza, Imran H.; Satyanarayana, M.; Gnaneshwar Rao, T.; Kaisary, Sujata

2010-04-01

95

An evolutionarily conserved role for SRm160 in 3'-end processing that functions independently of exon junction complex formation.  

PubMed

SRm160 (the SR-related nuclear matrix protein of 160 kDa) functions as a splicing coactivator and 3'-end cleavage-stimulatory factor. It is also a component of the splicing-dependent exon-junction complex (EJC), which has been implicated in coupling of pre-mRNA splicing with mRNA turnover and mRNA export. We have investigated whether the association of SRm160 with the EJC is important for efficient 3'-end cleavage. The EJC components RNPS1, REF, UAP56, and Y14 interact with SRm160. However, when these factors were tethered to transcripts, only SRm160 and RNPS1 stimulated 3'-end cleavage. Whereas SRm160 stimulated cleavage to a similar extent in the presence or absence of an active intron, stimulation of 3'-end cleavage by tethered RNPS1 is dependent on an active intron. Assembly of an EJC adjacent to the cleavage and polyadenylation signal in vitro did not significantly affect cleavage efficiency. These results suggest that SRm160 stimulates cleavage independently of its association with EJC components and that the cleavage-stimulatory activity of RNPS1 may be an indirect consequence of its ability to stimulate splicing. Using RNA interference (RNAi) in Caenorhabditis elegans, we determined whether interactions between SRm160 and the cleavage machinery are important in a whole organism context. Simultaneous RNAi of SRm160 and the cleavage factor CstF-50 (Cleavage stimulation factor 50-kDa subunit) resulted in late embryonic developmental arrest. In contrast, RNAi of CstF-50 in combination with RNPS1 or REFs did not result in an apparent phenotype. Our combined results provide evidence for an evolutionarily conserved interaction between SRm160 and the 3'-end cleavage machinery that functions independently of EJC formation. PMID:12944400

McCracken, Susan; Longman, Dasa; Johnstone, Iain L; Cáceres, Javier F; Blencowe, Benjamin J

2003-11-01

96

Cadherin Cytoplasmic Domains Inhibit the Cell Surface Localization of Endogenous E-Cadherin, Blocking Desmosome and Tight Junction Formation and Inducing Cell Dissociation  

PubMed Central

The downregulation of E-cadherin function has fundamental consequences with respect to cancer progression, and occurs as part of the epithelial–mesenchymal transition (EMT). In this study, we show that the expression of the Discosoma sp. red fluorescent protein (DsRed)-tagged cadherin cytoplasmic domain in cells inhibited the cell surface localization of endogenous E-cadherin, leading to morphological changes, the inhibition of junctional assembly and cell dissociation. These changes were associated with increased cell migration, but were not accompanied by the down-regulation of epithelial markers and up-regulation of mesenchymal markers. Thus, these changes cannot be classified as EMT. The cadherin cytoplasmic domain interacted with ?-catenin or plakoglobin, reducing the levels of ?-catenin or plakoglobin associated with E-cadherin, and raising the possibility that ?-catenin and plakoglobin sequestration by these constructs induced E-cadherin intracellular localization. Accordingly, a cytoplasmic domain construct bearing mutations that weakened the interactions with ?-catenin or plakoglobin did not impair junction formation and adhesion, indicating that the interaction with ?-catenin or plakoglobin was essential to the potential of the constructs. E-cadherin–?-catenin chimeras that did not require ?-catenin or plakoglobin for their cell surface transport restored cell–cell adhesion and junction formation. PMID:25121615

Ozawa, Masayuki; Kobayashi, Wakako

2014-01-01

97

High second-order nonlinearity by p-n junction formation in plasma enhanced chemical vapor deposition deposited hydrogenated amorphous silicon thin films  

NASA Astrophysics Data System (ADS)

High second-order nonlinearity as high as 115.9 pm/V was obtained through the formation of p-n junction using plasma-enhanced CVD deposition of hydrogenated amorphous silicon thin films on fused silica substrate without additional electrical poling to induce second harmonic generation in the isotropic amorphous materials. No second harmonic generation was observed for films deposited with only p or n type amorphous silicon. The built-in electrostatic field Edc of p-n junction was observed by measuring the I-V curve of the designed p-i-n layered films, and was found to be the main source of high second-order nonlinearity.

Liu, Qiming; Wu, Guoxing; Wang, Mingliang; Zhao, Xiujian; Du, Jincheng

2015-02-01

98

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

99

Nanotube junctions  

DOEpatents

The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

Crespi, Vincent Henry (Darien, IL); Cohen, Marvin Lou (Berkeley, CA); Louie, Steven Gwon Sheng (Berkeley, CA); Zettl, Alexander Karlwalter (Kensington, CA)

2003-01-01

100

Nanotube junctions  

DOEpatents

The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon; Zettl, Alexander Karlwalte

2004-12-28

101

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

102

Effects of rapid thermal annealing on the formation of shallow p+n junction by implanting BF2+ ions into thin metal films on Si substrate. I. Thin titanium films  

Microsoft Academic Search

High-quality Ti-silicided shallow p+n junctions have been fabricated by implanting BF+2 ions into thin Ti films on Si substrate and subsequent silicidation\\/drive-in by rapid thermal annealing (RTA) or conventional furnace annealing (CFA) under proper implant and anneal conditions. For both the RTA and CFA techniques, annealing temperatures higher than 800 °C degrade the junction formation because of more severe dopant

M. H. Juang; H. C. Cheng

1992-01-01

103

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

104

Using point defect engineering to reduce the effects of energy nonmonochromaticity of B ion beams on shallow junction formation  

NASA Astrophysics Data System (ADS)

We have shown that energy contamination introduced by deceleration technology, for increasing the beam currents available for low energy boron implants, can affect fabricated junctions adversely. Energy contamination at a level of 0.1% can extend the profile of 0.5 keV B implants 10 nm deeper after a 1050 °C spike annealing. A highly monoenergetic beam with energy contamination less than 0.1% is required for submicron devices. Furthermore, we have used MeV implantation as a technique of point defect engineering (PDE) to control boron diffusion. PDE can reduce boron clustering and enhance boron activation. Diffusion of B in the tail region has been reduced significantly and the boron profile is much sharper. PDE lowers the critical requirement for beam purity. We conclude that shallower and sharper box-like boron junctions can be achieved by PDE with sub-keV B implants with highly monoenergetic beams.

Shao, Lin; Chen, John; Zhang, Jianming; Tang, D.; Patel, Sanjay; Liu, Jiarui; Wang, Xuemei; Chu, Wei-Kan

2004-07-01

105

Josephson junction  

DOEpatents

A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material.

Wendt, Joel R. (Albuquerque, NM); Plut, Thomas A. (Albuquerque, NM); Martens, Jon S. (Sunnyvale, CA)

1995-01-01

106

Josephson junction  

DOEpatents

A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material. 10 figs.

Wendt, J.R.; Plut, T.A.; Martens, J.S.

1995-05-02

107

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). 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

108

Formation of a pn junction on an anisotropically etched GaAs surface using metalorganic chemical vapor deposition  

SciTech Connect

A continuous p-type GaAs epilayer has been deposited on an n-type sawtooth GaAs surface using metalorganic chemical vapor deposition. A wet chemical etching process was used to expose the intersecting (111)Ga and (1-bar1-bar1)Ga planes with 6 ..mu..m periodicity. Charge collection microscopy was used to verify the presence of the pn junction thus formed and to measure its depth. The ultimate goal of this work is to fabricate a V-groove GaAs cell with improved absorptivity, high short-circuit current, and tolerance to particle radiation.

Leon, R.P.; Bailey, S.G.; Mazaris, G.A.; Williams, W.D.

1986-10-13

109

Time-dependent effects of low-temperature atmospheric-pressure argon plasma on epithelial cell attachment, viability and tight junction formation in vitro  

NASA Astrophysics Data System (ADS)

The application of physical plasma to living tissues is expected to promote wound healing by plasma disinfection and stimulation of tissue regeneration. However, the effects of plasma on healthy cells must be studied and understood. In our experiments we used an argon plasma jet (kINPen®09) to gain insights into time-dependent plasma effects on cell attachment, viability and tight junction formation in vitro. Murine epithelial cells mHepR1 were suspended in complete cell culture medium and were irradiated with argon plasma (direct approach) for 30, 60 and 120 s. Suspecting that physical plasma may exert its effect via the medium, cell culture medium alone was first treated with argon plasma (indirect approach) and immediately afterwards, cells were added and also cultured for 24 h. Cell morphology and vitality were verified using light microscopy and an enzyme-linked immunosorbent assay. Already after 30 s of treatment the mHepR1 cells lost their capability to adhere and the cell vitality decreased with increasing treatment time. Interestingly, the same inhibitory effect was observed in the indirect approach. Furthermore, the argon plasma-treated culture medium-induced large openings of the cell's tight junctions, were verified by the zonula occludens protein ZO-1, which we observed for the first time in confluently grown epithelial cells.

Hoentsch, Maxi; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Nebe, J. Barbara

2012-01-01

110

Actin-related protein2/3 complex regulates tight junctions and terminal differentiation to promote epidermal barrier formation  

PubMed Central

The epidermis provides an essential seal from the external environment and retains fluids within the body. To form an effective barrier, cells in the epidermis must form tight junctions and terminally differentiate into cornified envelopes. Here, we demonstrate that the branched actin nucleator, the actin-related protein (Arp)2/3 complex, is unexpectedly required for both these activities. Loss of the ArpC3 subunit of the Arp2/3 complex resulted in minimal changes in the morphogenesis and architecture of this stratified squamous epithelium, but resulted in profound defects in its physiology. Mutant embryos did not develop an effective barrier to the external environment and died within hours of birth. We discovered two underlying causes for these effects. First, ArpC3 was essential for robust assembly and function of tight junctions, specialized cell–cell adhesions that restrict water loss in the epidermis. Second, there were defects in differentiation of the epidermis and the production of cornified envelopes, structures essential for barrier activity. Underlying this defect, we found that YAP was inappropriately active not only in the ArpC3 mutant tissue, but also in cultured cells. Inhibition of YAP activity rescued the differentiation and barrier defects caused by loss of ArpC3. These results demonstrate previously unappreciated roles for the Arp2/3 complex and highlight the functions of branched actin networks in a complex tissue. PMID:24043783

Zhou, Kang; Muroyama, Andrew; Underwood, Julie; Leylek, Rebecca; Ray, Samriddha; Soderling, Scott H.; Lechler, Terry

2013-01-01

111

Gap Junctions  

PubMed Central

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

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

2013-01-01

112

Development of the blood-retinal barrier in vitro: formation of tight junctions as revealed by occludin and ZO-1 correlates with the barrier function of chick retinal pigment epithelial cells.  

PubMed

To elucidate the molecular mechanisms of the blood-retinal barrier (BRB), we examined chick retinal tissues histochemically using antibodies against tight junction proteins such as ZO-1, 7H6 antigen, and occludin. Retinal pigment epithelial (RPE) cells in situ in chickens and late chick embryos expressed all of the tight junctional proteins examined, showing that tight junctions seal the cell borders of chick RPE cells in vivo. On the other hand, RPE cells isolated from late chick embryos and transferred in vitro did not express occludin, ZO-1 and 7H6 antigen. The effects of differentiation-inducing agents, such as retinoic acid, dexamethasone and dimethyl sulfoxide (DMSO) were tested. Only DMSO induced an increase in transepithelial electrical resistance (TER) in a time-dependent manner. Under supplementation with DMSO, immunofluorescently demonstrable occludin and ZO-1 were induced progressively at cell borders in parallel with the increase in TER that occurred with decreases in inulin and dextran permeability. Electron microscopically tight junction-like junctional apparatus were induced in RPE cells. These results indicated that tight junctions of RPE cells play an important role in the formation of the BRB. PMID:7556475

Konari, K; Sawada, N; Zhong, Y; Isomura, H; Nakagawa, T; Mori, M

1995-07-01

113

[Neuron-glial junction formation in cerebellum after electrical stimulation in presence of no-generating substance].  

PubMed

Molecular layer of frog (Rana temporaria) cerebellum was studied using light and electron microscope after electrical stimulation of parallel fibers in presence of NO-generating compound. Under these conditions, significant swelling of axonal terminals (boutons) of granular cells and astrocyte processes (AP) with a loss of cytoplasmic elements. However, along with the damaged structures, intact boutons were found with synaptic vesicles and APs containing glycogen granules. It is suggested that the remaining viable APs are capable of forming 1) protective glial "wrappings" around damaged synapses or boutons, and 2) neuron-glial junctions, that are formed due to transmission of synaptic vesicles through the damaged membrane of bouton into AP containing glycogen granules. It is also proposed that the presence of glycogen in APs under conditions of oxygen and glucose deficit may serve as the source of such energy-containing substrates, such as glucose and ATP, and thus may provide for neuronal survival in pathological states (ischemia/hypoxia). PMID:17583010

Samosudova, N V; Reutov, V P; Larionova, N P; Cha?lakhian, L M

2007-01-01

114

Graphene-SnO2 nanocomposites decorated with quantum tunneling junctions: preparation strategies, microstructures and formation mechanism.  

PubMed

Tin dioxide (SnO2) and graphene are versatile materials that are vitally important for creating new functional and smart materials. A facile, simple and efficient ultrasonic-assisted hydrothermal synthesis approach has been developed to prepare graphene-SnO2 nanocomposites (GSNCs), including three samples with graphene/Sn weight ratios = 1?:?2 (GSNC-2), 1?:?1 (GSNC-1), and graphene oxide/Sn weight ratio = 1?:?1 (GOSNC-1). Low-magnification electron microscopy analysis indicated that graphene was exfoliated and adorned with SnO2 nanoparticles, which were dispersed uniformly on both the sides of the graphene nanosheets. High-magnification electron microscopy analysis confirmed that the graphene-SnO2 nanocomposites presented network tunneling frameworks, which were decorated with the SnO2 quantum tunneling junctions. The size distribution of SnO2 nanoparticles was estimated to range from 3 to 5.5 nm. Comparing GSNC-2, GSNC-1, and GOSNC-1, GOSNC-1 was found to exhibit a significantly better the homogeneous distribution and a considerably smaller size distribution of SnO2 nanoparticles, which indicated that it was better to use graphene oxide as a supporting material and SnCl4·5H2O as a precursor to synthesize hybrid graphene-SnO2 nanocomposites. Experimental results suggest that the graphene-SnO2 nanocomposites with interesting SnO2 quantum tunneling junctions may be a promising material to facilitate the improvement of the future design of micro/nanodevices. PMID:25099195

Wang, Qingxiu; Wu, Xianzheng; Wang, Lijun; Chen, Zhiwen; Wang, Shilong

2014-09-28

115

The C-terminal domain of Fcj1 is required for formation of crista junctions and interacts with the TOB/SAM complex in mitochondria  

PubMed Central

Crista junctions (CJs) are tubular invaginations of the inner membrane of mitochondria that connect the inner boundary with the cristae membrane. These architectural elements are critical for mitochondrial function. The yeast inner membrane protein Fcj1, called mitofilin in mammals, was reported to be preferentially located at CJs and crucial for their formation. Here we investigate the functional roles of individual domains of Fcj1. The most conserved part of Fcj1, the C-terminal domain, is essential for Fcj1 function. In its absence, formation of CJ is strongly impaired and irregular, and stacked cristae are present. This domain interacts with full-length Fcj1, suggesting a role in oligomer formation. It also interacts with Tob55 of the translocase of outer membrane ?-barrel proteins (TOB)/sorting and assembly machinery (SAM) complex, which is required for the insertion of ?-barrel proteins into the outer membrane. The association of the TOB/SAM complex with contact sites depends on the presence of Fcj1. The biogenesis of ?-barrel proteins is not significantly affected in the absence of Fcj1. However, down-regulation of the TOB/SAM complex leads to altered cristae morphology and a moderate reduction in the number of CJs. We propose that the C-terminal domain of Fcj1 is critical for the interaction of Fcj1 with the TOB/SAM complex and thereby for stabilizing CJs in close proximity to the outer membrane. These results assign novel functions to both the C-terminal domain of Fcj1 and the TOB/SAM complex. PMID:22496419

Körner, Christian; Barrera, Miguel; Dukanovic, Jovana; Eydt, Katharina; Harner, Max; Rabl, Regina; Vogel, Frank; Rapaport, Doron; Neupert, Walter; Reichert, Andreas S.

2012-01-01

116

The C-terminal domain of Fcj1 is required for formation of crista junctions and interacts with the TOB/SAM complex in mitochondria.  

PubMed

Crista junctions (CJs) are tubular invaginations of the inner membrane of mitochondria that connect the inner boundary with the cristae membrane. These architectural elements are critical for mitochondrial function. The yeast inner membrane protein Fcj1, called mitofilin in mammals, was reported to be preferentially located at CJs and crucial for their formation. Here we investigate the functional roles of individual domains of Fcj1. The most conserved part of Fcj1, the C-terminal domain, is essential for Fcj1 function. In its absence, formation of CJ is strongly impaired and irregular, and stacked cristae are present. This domain interacts with full-length Fcj1, suggesting a role in oligomer formation. It also interacts with Tob55 of the translocase of outer membrane ?-barrel proteins (TOB)/sorting and assembly machinery (SAM) complex, which is required for the insertion of ?-barrel proteins into the outer membrane. The association of the TOB/SAM complex with contact sites depends on the presence of Fcj1. The biogenesis of ?-barrel proteins is not significantly affected in the absence of Fcj1. However, down-regulation of the TOB/SAM complex leads to altered cristae morphology and a moderate reduction in the number of CJs. We propose that the C-terminal domain of Fcj1 is critical for the interaction of Fcj1 with the TOB/SAM complex and thereby for stabilizing CJs in close proximity to the outer membrane. These results assign novel functions to both the C-terminal domain of Fcj1 and the TOB/SAM complex. PMID:22496419

Körner, Christian; Barrera, Miguel; Dukanovic, Jovana; Eydt, Katharina; Harner, Max; Rabl, Regina; Vogel, Frank; Rapaport, Doron; Neupert, Walter; Reichert, Andreas S

2012-06-01

117

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

118

Cesium encapsulation in single-walled carbon nanotubes via plasma ion irradiation: Application to junction formation and ab initio investigation  

Microsoft Academic Search

Using an approach different from the conventional vapor doping methods, Cs positive ions in a magnetized-plasma column are irradiated upon a negatively biased substrate which is covered with dispersed single-walled carbon nanotubes (SWNTs). The Cs ions are evidently observed inside SWNTs by the Z-contrast method in scanning transmission electron microscopy, demonstrating the formation of alkali-metal encapsulating SWNTs. Ab initio band

G.-H. Jeong; A. A. Farajian; R. Hatakeyama; T. Hirata; T. Yaguchi; K. Tohji; H. Mizuseki; Y. Kawazoe

2003-01-01

119

Stimulation of Chondrocyte Hypertrophy by Chemokine Stromal Cell-Derived Factor 1 in the Chondro-osseous Junction during Endochondral Bone Formation  

PubMed Central

During endochondral bone formation, chondrocytes undergo differentiation toward hypertrophy before they are replaced by bone and bone marrow. In this study, we found that a G-protein coupled receptor CXCR4 is predominantly expressed in hypertrophic chondrocytes, while its ligand, chemokine stromal cell derived factor 1 (SDF-1) is expressed in the bone marrow adjacent to hypertrophic chondrocytes. Thus, they are expressed in a complementary pattern in the chondro-osseous junction of the growth plate. Transfection of a CXCR4 cDNA into pre-hypertrophic chondrocytes results in a dose-dependent increase of hypertrophic markers including Runx2, Col X, and MMP-13 in response to SDF-1 treatment. In organ culture SDF-1 infiltrates cartilage and accelerates growth plate hypertrophy. Furthermore, a continuous infusion SDF-1 into the rabbit proximal tibial physis results in early physeal closure, which is accompanied by a transient elevation of type X collagen expression. Blocking SDF-1/CXCR4 interaction suppresses the expression of Runx2. Thus, interaction of SDF-1 and CXCR4 is required for Runx2 expression. Interestingly, knocking down Runx2 gene expression results in a decrease of CXCR4 mRNA levels in hypertrophic chondrocytes. This suggests a positive feedback loop of stimulation of chondrocyte hypertrophy by SDF-1/CXCR4, which is mediated by Runx2. PMID:20206617

Wei, Lei; Kanbe, Katsuaki; Lee, Mark; Wei, Xiaochun; Pei, Ming; Sun, Xiaojuan; Terek, Richard; Chen, Qian

2010-01-01

120

Cardiotonic steroid ouabain stimulates expression of blood-testis barrier proteins claudin-1 and -11 and formation of tight junctions in Sertoli cells.  

PubMed

The interaction of ouabain with the sodium pump induces signalling cascades resembling those triggered by hormone/receptor interactions. In the rat Sertoli cell line 93RS2, ouabain at low concentrations stimulates the c-Src/c-Raf/Erk1/2 signalling cascade via its interaction with the ?4 isoform of the sodium pump expressed in these cells, leading to the activation of the transcription factor CREB. As a result of this signalling sequence, ouabain stimulates expression of claudin-1 and claudin-11, which are also controlled by a CRE promoter. Both of these proteins are known to be essential constituents of tight junctions (TJ) between Sertoli cells, and as a result of the ouabain-induced signalling TJ formation between neighbouring Sertoli cells is significantly enhanced by the steroid. Thus, ouabain-treated cell monolayers display higher transepithelial resistance and reduced free diffusion of FITC-coupled dextran in tracer diffusion assays. Taking into consideration that the formation of TJ is indispensable for the maintenance of the blood-testis barrier (BTB) and therefore for male fertility, the actions of ouabain described here and the fact that this and other related cardiotonic steroids (CTS) are produced endogenously suggest a direct influence of ouabain/sodium pump interactions on the maintenance of the BTB and thereby an effect on male fertility. Since claudin-1 and claudin-11 are also present in other blood-tissue barriers, one can speculate that ouabain and perhaps other CTS influence the dynamics of these barriers as well. PMID:25666991

Dietze, Raimund; Shihan, Mazen; Stammler, Angelika; Konrad, Lutz; Scheiner-Bobis, Georgios

2015-04-15

121

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization  

NASA Astrophysics Data System (ADS)

Design and optimization of n-type doped regions in germanium by solid phase epitaxial recrystallization (SPER) have been studied by the authors. A systematic study is presented of process variables that influence activation and thermal stability, including preamorphization, coimplants, recrystallization temperature, and postrecrystallization thermal treatments. Unlike silicon, activation after recrystallization in germanium is not optimum where the postrecrystallization thermal budget is kept to a minimum. With the aid of modeling, a maximum peak activation of 7×1019 cm-3 was extracted. A steady increase in sheet resistance during postrecrystallization anneals confirms the formation of metastable activation by SPER. It is predicted that active concentrations of 6-8×1019 cm-3 are sufficient to meet targets for sub-20 nm technologies.

Duffy, R.; Shayesteh, M.; White, M.; Kearney, J.; Kelleher, A.-M.

2010-06-01

122

Junction formation at the interface of CdS/CuInxGa(1 - x)Se2  

NASA Astrophysics Data System (ADS)

The interfacial band alignment and chemical composition at the cadmium sulfide (CdS)/copper indium gallium diselenide (CuInx Ga1-x Se2?:?CIGS) heterojunction was investigated by photoelectron spectroscopy. Over the two different interfaces made by either thermal deposition of CdS on a CIGS film or step-by-step etching of a chemical-bath deposited (CBD)-CdS/CIGS film by Ar+ ions, the valence band maximum and conduction band minimum were determined using ultraviolet photoelectron spectroscopy and inverse photoemission spectroscopy, respectively. Concurrently, x-ray photoelectron spectroscopy was used to trace chemical changes across the interface. Both interfaces showed a In-rich and Cu-deficient profile. The thermal deposition of CdS on CIGS induces Cd-Cu intermixing and nonstoichiometric CdS formation associated with a strong band bending and high electron injection barrier. However, the CBD-CdS layer shows a rather sharp interface and negligible electron injection barrier in the conduction band, which will show better solar cell characteristics.

Park, Soon Mi; Kim, Tae Gun; Duck Chung, Yong; Cho, Dae-Hyung; Kim, Jeha; Kim, Kyung Joong; Yi, Yeonjin; Kim, Jeong Won

2014-08-01

123

Rapid Determination of Gap Junction Formation Using HeLa Cells Microinjected with cDNAs Encoding Wild-Type and Chimeric Connexins  

Microsoft Academic Search

A procedure for rapidly determining the functionality of gap junctions constructed of recombinant connexins in communication-deficient HeLa cells is described. Nuclear microinjection of cDNA encoding wild-type connexins (Cx) 26, 32, 43, and a range of connexin-aequorin (Cx-Aeq) chimerase resulted in generation of gap junction intercellular communication channels. Expression of recombinant protein was detected in >95% of cells 18–72 h following

C. H. George; P. E. M. Martin; W. H. Evans

1998-01-01

124

Self-organising behavior of arrays of nonidentical Josephson junctions  

Microsoft Academic Search

In this work the global behavior of a parallel array of Josephson junctions is investigated. The single junction, driven by a periodic forcing, behaves chaotically, and is locally coupled in an array of 128 junctions, closed on a parallel resistive load. The array exhibits spatio-temporal chaos. When a spatial diversity is applied, self-organization and pattern formation arise. Moreover, when the

Luigi Fortuna; Mattia Frasca; Alessandro Rizzo

2002-01-01

125

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.

126

Post-translational integration and oligomerization of connexin 26 in plasma membranes and evidence of formation of membrane pores: implications for the assembly of gap junctions.  

PubMed Central

Gap-junction channels provide a widespread intercellular signalling mechanism. They are constructed of a family of connexin membrane proteins that thread across the membrane four times and oligomerize to generate hexameric gap-junction hemichannels. Using an in vitro cell-free transcription/translation system, we demonstrate that connexin (Cx) 26, one of the smallest connexins, is integrated directly in a post-translational manner into plasma membranes. Protein-cleavage studies of Cx26 integrated into plasma membranes indicate a similar native transmembrane topography to that of Cx26 integrated co-translationally into microsomes. Cx26 integrated post-translationally into plasma membranes oligomerizes and, when incorporated into liposomes, provides permeability to ascorbic acid, suggesting that gap-junction hemichannels are generated. The results provide the basis of a novel alternative mechanism for spontaneous assembly in plasma membranes of Cx26 gap-junction hemichannels that occurs independently of the conventional biogenesis of gap junctions involving connexin trafficking and oligomerization via membrane components of the secretory pathway. PMID:11985493

Ahmad, Shoeb; Evans, W Howard

2002-01-01

127

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.

128

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Formation of p—n junctions and ohmic contacts with GaAs by laser solid-phase diffusion  

NASA Astrophysics Data System (ADS)

An experimental investigation was made of the electrophysical properties of p—n junctions and ohmic contacts formed by laser solid-phase diffusion of, respectively, zinc and a contact group of elements (Au—Au : Ge) in a plate of n-type GaAs. The diffusion was induced by radiation from a cw CO2 laser. The zero-bias resistance of the p—n junctions was ~1010 ? and the leakage current did not exceed 1 nA under a reverse bias voltage of 8 V. A typical resistance of the nonrectifying contacts was 5×10-7 ? cm2.

Bonchik, A. Yu; Kiyak, S. G.; Mikhailova, G. N.; Pokhmurskaya, A. V.; Savitskii, G. V.

1995-01-01

129

The Small GTPase Rab13 Regulates Assembly of Functional Tight Junctions in Epithelial Cells  

Microsoft Academic Search

Abstract Junctional complexes such as tight junctions (TJ), and adherens junctions are required for maintaining cell surface asymmetry,and polarized transport in epithelial cells. We have shown that Rab13 is recruited to junctional complexes,from a cytosolic pool after cell-cell contact formation. In this study, we investigate the role of Rab13 in modulating TJ structure and

Anne-Marie Marzesco; Irene Dunia; Rudy Pandjaitan; Michel Recouvreur; Daniel Dauzonne; Ennio Lucio Benedetti; Daniel Louvard; Ahmed Zahraoui

2002-01-01

130

Shh and Gli3 regulate formation of the telencephalic–diencephalic junction and suppress an isthmus-like signaling source in the forebrain  

Microsoft Academic Search

In human holoprosencephaly (HPE), the forebrain does not separate fully into two hemispheres. Further, the border between the telencephalon and diencephalon, the telencephalic\\/diencephalic junction (TDJ), is often indistinct, and the ventricular system can be blocked at the third ventricle, creating a forebrain ‘holosphere’. Mice deficient in Sonic Hedgehog (Shh) have previously been described to show HPE and associated cyclopia. Here

Brian G. Rash; Elizabeth A. Grove

2011-01-01

131

Materials Science and Engineering B 114115 (2004) 390396 Fundamental characterization of the effect of nitride sidewall spacer  

E-print Network

­6] and thereby enhances the amount of B dose loss into the oxide from the Si. Lesser retained dose leads of the effect of nitride sidewall spacer process on boron dose loss in ultra-shallow junction formation P complementary metal oxide semiconductor (CMOS) process flows. In this work, we have investigated the effect

Dunham, Scott

132

Growth sequence and interface formation in the Fe/MgO/Fe(001) tunnel junction analyzed by surface x-ray diffraction  

SciTech Connect

We present a surface x-ray diffraction study of the interface geometric structure in the Fe/MgO/Fe(001) magnetic tunnel junction (MTJ). While the lower MgO/Fe(001) interface is characterized by a substoichiometric FeO{sub x} (x=0.6{+-}0.1) layer in agreement with previous studies, growth of Fe on the MgO spacer and the upper Fe/MgO interface structure strongly depends on the preparation method. If 0.4 monolayers of Fe are initially deposited in ambient oxygen atmosphere (p=10{sup -7} mbar) followed by Fe deposition under ultrahigh-vacuum (UHV) conditions, structural coherence across the trilayer junction is observed. In this case, substoichiometric FeO{sub x} layers are present at both Fe/MgO interfaces corresponding to a symmetric MTJ structure. In contrast, lattice registry is not preserved if Fe deposition is carried out solely under UHV conditions. Our results might have important implications for the preparation of magnetic tunnel junctions optimized to achieve giant tunneling-magnetoresistance amplitudes.

Tusche, C.; Meyerheim, H. L.; Kirschner, J. [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany); Jedrecy, N. [Institut des NanoSciences de Paris, Universites Paris 6 et 7 et CNRS-UMR 7588, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Renaud, G. [CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble (France)

2006-11-15

133

Orientation-controlled single-molecule junctions.  

PubMed

The conductivity of a single aromatic ring, perpendicular to its plane, is determined using a new strategy under ambient conditions and at room temperature by a combination of molecular assembly, scanning tunneling microscopy (STM) imaging, and STM break junction (STM-BJ) techniques. The construction of such molecular junctions exploits the formation of highly ordered structures of flat-oriented mesitylene molecules on Au(111) to enable direct tip/? contacts, a result that is not possible by conventional methods. The measured conductance of Au/?/Au junction is about 0.1?G(o)?, two orders of magnitude higher than the conductance of phenyl rings connected to the electrodes by standard anchoring groups. Our experiments suggest that long-range ordered structures, which hold the aromatic ring in place and parallel to the surface, are essential to increase probability of the formation of orientation-controlled molecular junctions. PMID:25044431

Afsari, Sepideh; Li, Zhihai; Borguet, Eric

2014-09-01

134

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

135

Connexin43 gap junctions in normal, regenerating, and cultured mouse bone marrow and in human leukemias: their possible involvement in blood formation.  

PubMed Central

Communicating channels called gap junctions are thought to play a ubiquitous part in cell growth and development. Based on earlier work, we have recently found functional evidence of their presence in human and mouse bone marrow. In this study we studied the cell-type association of the gap junction channel-forming protein, connexin, in mouse and human bone marrow under different physiological and pathological conditions and tested the pathway of communication in bone marrow cultures. For high-resolution antigen demonstration we took advantage of semi-thin resin sections, antigen retrieval methods, immunofluorescence, and confocal laser scanning microscopy. Connexin43 (Cx43) and its mRNA were consistently expressed in human and rodent marrow. Cx37 was found only in the arteriolar endothelium, but neither Cx32 nor -26 were expressed. In tissue sections, the immunostained junctions appeared as dots, which were digitally measured and counted. Their average size was 0.40 mm in human and 0.49 mm in mice marrow. There were at least twice as many gap junctions in the femoral midshaft of 6-week-old mice (1.75 x 10(5)/mm3) as in those older than 12 weeks (0.89 x 10(5)/mm3). Most Cx43 was associated with collagen III+ endosteal and adventitial stromal cells and with megakaryocytes. Elsewhere, they were few and randomly distributed between all kinds of hematopoietic cells. In the femoral epiphysis of juvenile mice, stromal cell processes full of Cx43 enmeshed three to six layers of hematopoietic cells near the endosteum. The same pattern was seen in the midshaft of regenerating mouse marrow 3 to 5 days after cytotoxic treatment with 5-fluorouracil. Functional tests in cultures showed the transfer of small fluorescent dyes, Lucifer Yellow and 2',7'-bis-(2-carboxyethyl)-5, 6-carboxyfluorescein, between stromal cells and in rare cases between stromal and hematopoietic cells too. The stromal cells were densely packed with Cx43 and we found aggregates of connexon particles in their membrane replicas. In normocellular human bone marrow, gap junctions were as rare as in adult mouse and similarly distributed, except that they were also on adipocytic membranes. In a few leukemic samples, characterized by an increased stromal/hematopoietic cell ratio, there were two- to fourfold more Cx43 (2.8 x 10(5) to 3.9 x 10(5)/mm3) than in the normal (1.0 x 10(5) to 1.2 x 10(5)/mm3). The cases included a hypoplastic acute lymphoblastic leukemia, an acute myeloid leukemia (French-American-British classification M4-5), a case of myelodysplastic syndrome with elevated number of megakaryocytes, and a CD34+ acute hemoblastosis, probably acute myeloid leukemia (French-American-British classification M7). Taken together, our results indicate that direct cell-cell communication may be involved in hematopoiesis, ie, in developmentally active epiphyseal bone marrow and when there is a demand for progenitors in regeneration. However, gap junctions may not play as important a role in resting adult hematopoiesis and in leukemias. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 10 PMID:9546360

Krenacs, T.; Rosendaal, M.

1998-01-01

136

comK Prophage Junction Fragments as Markers for Listeria monocytogenes Genotypes Unique to Individual Meat and Poultry Processing Plants and a Model for Rapid Niche-Specific Adaptation, Biofilm Formation, and Persistence ? †  

PubMed Central

Different strains of Listeria monocytogenes are well known to persist in individual food processing plants and to contaminate foods for many years; however, the specific genotypic and phenotypic mechanisms responsible for persistence of these unique strains remain largely unknown. Based on sequences in comK prophage junction fragments, different strains of epidemic clones (ECs), which included ECII, ECIII, and ECV, were identified and shown to be specific to individual meat and poultry processing plants. The comK prophage-containing strains showed significantly higher cell densities after incubation at 30°C for 48 h on meat and poultry food-conditioning films than did strains lacking the comK prophage (P < 0.05). Overall, the type of strain, the type of conditioning film, and the interaction between the two were all highly significant (P < 0.001). Recombination analysis indicated that the comK prophage junction fragments in these strains had evolved due to extensive recombination. Based on the results of the present study, we propose a novel model in which the concept of defective comK prophage was replaced with the rapid adaptation island (RAI). Genes within the RAI were recharacterized as “adaptons,” as these genes may allow L. monocytogenes to rapidly adapt to different food processing facilities and foods. If confirmed, the model presented would help explain Listeria's rapid niche adaptation, biofilm formation, persistence, and subsequent transmission to foods. Also, comK prophage junction fragment sequences may permit accurate tracking of persistent strains back to and within individual food processing operations and thus allow the design of more effective intervention strategies to reduce contamination and enhance food safety. PMID:21441318

Verghese, Bindhu; Lok, Mei; Wen, Jia; Alessandria, Valentina; Chen, Yi; Kathariou, Sophia; Knabel, Stephen

2011-01-01

137

comK prophage junction fragments as markers for Listeria monocytogenes genotypes unique to individual meat and poultry processing plants and a model for rapid niche-specific adaptation, biofilm formation, and persistence.  

PubMed

Different strains of Listeria monocytogenes are well known to persist in individual food processing plants and to contaminate foods for many years; however, the specific genotypic and phenotypic mechanisms responsible for persistence of these unique strains remain largely unknown. Based on sequences in comK prophage junction fragments, different strains of epidemic clones (ECs), which included ECII, ECIII, and ECV, were identified and shown to be specific to individual meat and poultry processing plants. The comK prophage-containing strains showed significantly higher cell densities after incubation at 30°C for 48 h on meat and poultry food-conditioning films than did strains lacking the comK prophage (P < 0.05). Overall, the type of strain, the type of conditioning film, and the interaction between the two were all highly significant (P < 0.001). Recombination analysis indicated that the comK prophage junction fragments in these strains had evolved due to extensive recombination. Based on the results of the present study, we propose a novel model in which the concept of defective comK prophage was replaced with the rapid adaptation island (RAI). Genes within the RAI were recharacterized as "adaptons," as these genes may allow L. monocytogenes to rapidly adapt to different food processing facilities and foods. If confirmed, the model presented would help explain Listeria's rapid niche adaptation, biofilm formation, persistence, and subsequent transmission to foods. Also, comK prophage junction fragment sequences may permit accurate tracking of persistent strains back to and within individual food processing operations and thus allow the design of more effective intervention strategies to reduce contamination and enhance food safety. PMID:21441318

Verghese, Bindhu; Lok, Mei; Wen, Jia; Alessandria, Valentina; Chen, Yi; Kathariou, Sophia; Knabel, Stephen

2011-05-01

138

Annexin A2 is Required for Endothelial Cell Junctional Response to S1P  

E-print Network

and focal adhesion proteins with immunofluorescence staining. Removal of the ANXA2 protein in ECs resulted in the formation of wide reticular junctions in 2D, affecting localization of adherens junction proteins such as VE-cadherin, platelet endothelial...

Smith, Rebecca

2014-01-14

139

Plasmodium falciparum Adhesion on Human Brain Microvascular Endothelial Cells Involves Transmigration-Like Cup Formation and Induces Opening of Intercellular Junctions  

PubMed Central

Cerebral malaria, a major cause of death during malaria infection, is characterised by the sequestration of infected red blood cells (IRBC) in brain microvessels. Most of the molecules implicated in the adhesion of IRBC on endothelial cells (EC) are already described; however, the structure of the IRBC/EC junction and the impact of this adhesion on the EC are poorly understood. We analysed this interaction using human brain microvascular EC monolayers co-cultured with IRBC. Our study demonstrates the transfer of material from the IRBC to the brain EC plasma membrane in a trogocytosis-like process, followed by a TNF-enhanced IRBC engulfing process. Upon IRBC/EC binding, parasite antigens are transferred to early endosomes in the EC, in a cytoskeleton-dependent process. This is associated with the opening of the intercellular junctions. The transfer of IRBC antigens can thus transform EC into a target for the immune response and contribute to the profound EC alterations, including peri-vascular oedema, associated with cerebral malaria. PMID:20686652

Jambou, Ronan; Combes, Valery; Jambou, Marie-Jose; Weksler, Babeth B.; Couraud, Pierre-Olivier; Grau, Georges E.

2010-01-01

140

The impact of TiSi2 on shallow junctions  

Microsoft Academic Search

We have examined the impact of TiSi2 formation on the properties of shallow n+ and p+ junctions (0.17-0.20 um) in Si. The deposited Ti thickness was varied from 300A to 1000A. The p+ junctions developed high leakage currents after reaction with Ti of initial thickness greater than 700A while the n+ junctions were not degraded. In these studies LOCOS isolation

D. C. Chen; T. R. Cass; J. E. Turner; P. Merchant; K. Y. Chiu

1985-01-01

141

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

142

Cell junctions in early embryos of squid (Loligo pealei).  

PubMed

Squid embryos examined by freeze-fracture and thin-section electron microscopy exhibit identifiable gap junctions during mid-cleavage stages (stages 7-8), and junctional complexes composed of adherent appositions, elaborate septate junctions and gap junctions at slightly later stages (stages 12-13). During germinal layer establishment (stages 12-13) cytoplasmic bridges frequently link the embryonic cells. The presence of gap junctions in cleavage-stage embryos provides the morphological substrate for a demonstrated pathway of direct cell-cell communication that is modifiable by experimental treatments and may be physiologically regulatable. The existence of septate junctions and adherent contacts at later stages suggests that some functional specialization, perhaps the establishment of a strongly joined framework of cells at the surface of the embryo, accompanies the formation of germinal layers. PMID:3986876

Ginzberg, R D; Morales, E A; Spray, D C; Bennett, M V

1985-01-01

143

Three-junction solar cell  

DOEpatents

A photovoltaic solar cell is formed in a monolithic semiconductor. The cell contains three junctions. In sequence from the light-entering face, the junctions have a high, a medium, and a low energy gap. The lower junctions are connected in series by one or more metallic members connecting the top of the lower junction through apertures to the bottom of the middle junction. The upper junction is connected in voltage opposition to the lower and middle junctions by second metallic electrodes deposited in holes 60 through the upper junction. The second electrodes are connected to an external terminal.

Ludowise, Michael J. (Cupertino, CA)

1986-01-01

144

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

145

A Kinetic Monte Carlo model for material aging: Simulations of second phase formation at Au/Bi{sub 2}Te{sub 3} junction in oxygen environments  

SciTech Connect

Electronic properties of semiconductor devices are sensitive to defects such as second phase precipitates, grain sizes, and voids. These defects can evolve over time especially under oxidation environments and it is therefore important to understand the resulting aging behavior in order for the reliable applications of devices. In this paper, we propose a kinetic Monte Carlo framework capable of simultaneous simulation of the evolution of second phases, precipitates, grain sizes, and voids in complicated systems involving many species including oxygen. This kinetic Monte Carlo model calculates the energy barriers of various events based directly on the experimental data. As a first step of our model implementation, we incorporate the second phase formation module in the parallel kinetic Monte Carlo codes SPPARKS. Selected aging simulations are performed to examine the formation of second phase precipitates at the eletroplated Au/Bi{sub 2}Te{sub 3} interface under oxygen and oxygen-free environments, and the results are compared with the corresponding experiments.

Zhou, X. W., E-mail: xzhou@sandia.gov [Mechanics of Materials Department, Sandia National Laboratories, Livermore, California 94550 (United States); Yang, N. Y. C. [Energy Nanomaterials Department, Sandia National Laboratories, Livermore, California 94550 (United States)

2014-03-14

146

Holographic SIS Josephson Junction  

E-print Network

We construct a holographic model for the superconductor-insulator-superconductor (SIS) Josephson junction at zero temperature by considering a complex scalar field coupled with a Maxwell field in the four-dimensional anti-de Sitter soliton background. From the gravity side we reproduce the sine relation between the Josephson current and the phase difference across the junction. We also study the dependence of the maximal current on the dimension of the condensate operator and on the width of the junction, and obtain expected results.

Yong-Qiang Wang; Yu-Xiao Liu; Rong-Gen Cai; Shingo Takeuchi; Hai-Qing Zhang

2012-09-23

147

Nanowire transistors without junctions.  

PubMed

All existing transistors are based on the use of semiconductor junctions formed by introducing dopant atoms into the semiconductor material. As the distance between junctions in modern devices drops below 10 nm, extraordinarily high doping concentration gradients become necessary. Because of the laws of diffusion and the statistical nature of the distribution of the doping atoms, such junctions represent an increasingly difficult fabrication challenge for the semiconductor industry. Here, we propose and demonstrate a new type of transistor in which there are no junctions and no doping concentration gradients. These devices have full CMOS functionality and are made using silicon nanowires. They have near-ideal subthreshold slope, extremely low leakage currents, and less degradation of mobility with gate voltage and temperature than classical transistors. PMID:20173755

Colinge, Jean-Pierre; Lee, Chi-Woo; Afzalian, Aryan; Akhavan, Nima Dehdashti; Yan, Ran; Ferain, Isabelle; Razavi, Pedram; O'Neill, Brendan; Blake, Alan; White, Mary; Kelleher, Anne-Marie; McCarthy, Brendan; Murphy, Richard

2010-03-01

148

Studies of silicon PN junction solar cells  

NASA Technical Reports Server (NTRS)

Silicon pn junction solar cells made with low-resistivity substrates show poorer performance than traditional theory predicts. The purpose of this research was to identify and characterize the physical mechanisms responsible for the discrepancy. Attention was concentrated on the open circuit voltage in shallow junction cells of 0.1 ohm-cm substrate resistivity. A number of possible mechanisms that can occur in silicon devices were considered. Two mechanisms which are likely to be of main importance in explaining the observed low values of open-circuit voltage were found: (1) recombination losses associated with defects introduced during junction formation, and (2) inhomogeneity of defects and impurities across the area of the cell. To explore these theoretical anticipations, various diode test structures were designed and fabricated and measurement configurations for characterizing the defect properties and the areal inhomogeneity were constructed.

Lindholm, F. A.

1975-01-01

149

Altered patterns of cardiac intercellular junction distribution in hypertrophic cardiomyopathy.  

PubMed Central

OBJECTIVE: To examine the distribution pattern of intercellular junctions (the mechanically coupling desmosomes and the electrically coupling gap junctions) in hypertrophic cardiomyopathy (HCM) hearts showing myofibre disarray. DESIGN: Samples from six necropsied hearts were studied, representing the interventricular septum and the free walls of the left and right ventricles. Immunohistochemical labelling of desmoplakin was used as a marker for desmosomes, and of connexin43 as a marker for gap junctions, in single and double stainings. The slides were examined by confocal laser scanning microscopy. RESULTS: Marked disorganisation of intercalated discs was observed in areas featuring myofibre disarray. Besides overall derangement, localised abnormalities in desmosome organisation were evident, which included: (1) the formation of abnormally enlarged megadiscs; (2) the presence of intersecting disc structures; and (3) aberrant side to side desmosomal connections. Gap junctional abnormalities included: (1) random distribution of gap junctions over the surface of myocytes, rather than localisation to intercalated discs; (2) abundant side to side gap junction connections between adjacent myocytes; and (3) formation of abnormally shaped gap junctions. Circles of myocytes continuously interconnected by gap junctions were also observed. Regions of the diseased hearts lacking myofibre disarray, and control hearts of normal patients and patients with other cardiac diseases, did not show these alterations. CONCLUSIONS: The disorganisation of the intercellular junctions associated with myofibre disarray in HCM may play an important role in the pathophysiological manifestations of the disease. The remodelling of gap junction distribution may underlie the formation of an arrhythmogenic substrate, thereby contributing to the generation and maintenance of cardiac arrhythmias associated with HCM. Images PMID:8944586

Sepp, R.; Severs, N. J.; Gourdie, R. G.

1996-01-01

150

Quantum junction solar cells.  

PubMed

Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO(2)); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. PMID:22881834

Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H

2012-09-12

151

Adherens junctions in C. elegans embryonic morphogenesis.  

PubMed

Caenorhabditis elegans provides a simplified, in vivo model system in which to study adherens junctions (AJs) and their role in morphogenesis. The core AJ components-HMR-1/E-cadherin, HMP-2/?-catenin and HMP-1/?-catenin-were initially identified through genetic screens for mutants with body axis elongation defects. In early embryos, AJ proteins are found at sites of contact between blastomeres, and in epithelial cells AJ proteins localize to the multifaceted apical junction (CeAJ)-a single structure that combines the adhesive and barrier functions of vertebrate adherens and tight junctions. The apically localized polarity proteins PAR-3 and PAR-6 mediate formation and maturation of junctions, while the basolaterally localized regulator LET-413/Scribble ensures that junctions remain apically positioned. AJs promote robust adhesion between epithelial cells and provide mechanical resistance for the physical strains of morphogenesis. However, in contrast to vertebrates, C. elegans AJ proteins are not essential for general cell adhesion or for epithelial cell polarization. A combination of conserved and novel proteins localizes to the CeAJ and works together with AJ proteins to mediate adhesion. PMID:22674076

Armenti, Stephen T; Nance, Jeremy

2012-01-01

152

Junctional Membrane Uncoupling  

PubMed Central

The permeability of the membrane surfaces where cells are in contact (junctional membranes) in Chironomus salivary glands depends on Ca++ and Mg++. When the concentration of these ions at the junctional membranes is raised sufficiently, these normally highly permeable membranes seal off; their permeability falls one to three orders, as they approach the nonjunctional membranes in conductance. This permeability transformation is achieved in three ways: (a) by iontophoresis of Ca++ into the cell; (b) by entry of Ca++ and/or Mg++ from the extracellular fluid into the cell through leaks in the cell surface membrane (e.g., injury); or (c) by entry of these ions through leaks arising, probably primarily in the perijunctional insulation, due to trypsin digestion, anisotonicity, alkalinity, or chelation. Ca++ and Mg++ appear to have three roles in the junctional coupling processes: (a) in the permeability of the junctional membranes; (b) in the permeability of the perijunctional insulation; and (c) a role long known— in the mechanical stability of the cell junction. The two latter roles may well be closely interdependent, but the first is clearly independent of the others. PMID:6050971

Loewenstein, W. R.; Nakas, M.; Socolar, S. J.

1967-01-01

153

Fractional order junctions  

NASA Astrophysics Data System (ADS)

Gottfried Leibniz generalized the derivation and integration, extending the operators from integer up to real, or even complex, orders. It is presently recognized that the resulting models capture long term memory effects difficult to describe by classical tools. Leon Chua generalized the set of lumped electrical elements that provide the building blocks in mathematical models. His proposal of the memristor and of higher order elements broadened the scope of variables and relationships embedded in the development of models. This paper follows the two directions and proposes a new logical step, by generalizing the concept of junction. Classical junctions interconnect system elements using simple algebraic restrictions. Nevertheless, this simplistic approach may be misleading in the presence of unexpected dynamical phenomena and requires including additional “parasitic” elements. The novel ?-junction includes, as special cases, the standard series and parallel connections and allows a new degree of freedom when building models. The proposal motivates the search for experimental and real world manifestations of the abstract conjectures.

Machado, J. Tenreiro

2015-01-01

154

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

155

PERMEABLE JUNCTIONAL COMPLEXES  

PubMed Central

Ionic lanthanum has been used to study transepithelial ion permeation in in vitro rabbit gallbladder and intestine (ileum) by adding 1 mM La3+ to only the mucosal bathing solution. Transepithelial fluid transport electrical potential differences (p.d.), and resistances were measured. During La3+ treatment the gallbladder's rate of active solute-coupled fluid transport remained constant, the resistance increased, and the 2:1 NaCl diffusion p.d. decreased. Mucosa-to-serosa fluxes of 140La3+ were measured and indicate a finite permeability of the gallbladder to La3+. La3+ also increased the transepithelial resistance and p d. of ileum. Electron microscopic examination of La3+-treated gallbladder showed: (a) good preservation of the fine structure, (b) electron-opaque lanthanum precipitates in almost every lateral intercellular space, most frequently near the apical end of the lateral spaces close to or within the junctional complex, (c) lanthanum among the subjacent muscle and connective tissue layers, and (d) lanthanum filling almost the entire length of so-called "tight" junctions. No observations were made which unequivocally showed the penetration of lanthanum into the gallbladder cells. Electron micrographs of similar La3+-treated ilea showed lanthanum deposits penetrating the junctional complexes. These results coupled with other physiological studies indicate that the low resistance pathway for transepithelial ion permeation in gallbladder and ileum is through the tight junctions A division of salt-transporting epithelia into two main groups, those with "leaky" junctional complexes and those with tight junctional complexes, has been proposed. PMID:5040861

Machen, Terry E.; Erlij, David; Wooding, F. B. P.

1972-01-01

156

Amorphous molecular junctions produced by ion irradiation on carbon nanotubes  

NASA Astrophysics Data System (ADS)

Experiments and molecular dynamics have demonstrated that electron irradiation could create molecular junctions between crossed single-wall carbon nanotubes. Recently molecular dynamics computation predicted that ion irradiation could also join single-walled carbon nanotubes. Employing carbon ion irradiation on multi-walled carbon nanotubes, we find that these nanotubes evolve into amorphous carbon nanowires, more importantly, during the process of which various molecular junctions of amorphous nanowires are formed by welding from crossed carbon nanotubes. It demonstrates that ion-beam irradiation could be an effective way not only for the welding of nanotubes but also for the formation of nanowire junctions.

Wang, Zhenxia; Yu, Liping; Zhang, Wei; Ding, Yinfeng; Li, Yulan; Han, Jiaguang; Zhu, Zhiyuan; Xu, Hongjie; He, Guowei; Chen, Yi; Hu, Gang

2004-04-01

157

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

158

Graphene Nanoribbon based T Junctions  

Microsoft Academic Search

Graphene nanoribbons (GNRs) based T junctions were designed and studied in this paper. These junctions were made up of shoulders (zigzag GNRs) joined with stems (armchair GNRs). We demonstrated the intrinsic transport properties and effective boron (or nitrogen) doping of the junctions by using first principles quantum transport simulation. Several interesting results were found: i) The I-V characteristics of the

Fangping OuYang; Bing Huang; Zuanyi Li; Xiao jin; Hui Xu

2008-01-01

159

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

160

Non-linear effects in high energy cluster ion implantation  

Microsoft Academic Search

Cluster ion implantation realizes ultra-shallow (<50 nm) junction formation. Cluster ions can provide a low-energy and high-current beam, because each constituent atom in the cluster, with sizes of a few thousands, has an energy of only a few eV. Non-linear effects of high energy cluster ion implantation caused by multiple-collisions and high-density energy deposition within a local surface region, have

D. Takeuchi; T. Aoki; J. Matsuo; I. Yamada

1997-01-01

161

Gliotactin, a novel marker of tricellular junctions, is necessary for septate junction development in Drosophila  

PubMed Central

Septate junctions (SJs), similar to tight junctions, function as transepithelial permeability barriers. Gliotactin (Gli) is a cholinesterase-like molecule that is necessary for blood–nerve barrier integrity, and may, therefore, contribute to SJ development or function. To address this hypothesis, we analyzed Gli expression and the Gli mutant phenotype in Drosophila epithelia. In Gli mutants, localization of SJ markers neurexin-IV, discs large, and coracle are disrupted. Furthermore, SJ barrier function is lost as determined by dye permeability assays. These data suggest that Gli is necessary for SJ formation. Surprisingly, Gli distribution only colocalizes with other SJ markers at tricellular junctions, suggesting that Gli has a unique function in SJ development. Ultrastructural analysis of Gli mutants supports this notion. In contrast to other SJ mutants in which septa are missing, septa are present in Gli mutants, but the junction has an immature morphology. We propose a model, whereby Gli acts at tricellular junctions to bind, anchor, or compact SJ strands apically during SJ development. PMID:12782681

Schulte, Joost; Tepass, Ulrich; Auld, Vanessa J.

2003-01-01

162

PTEN controls junction lengthening and stability during cell rearrangement in epithelial tissue.  

PubMed

Planar cell rearrangements control epithelial tissue morphogenesis and cellular pattern formation. They lead to the formation of new junctions whose length and stability determine the cellular pattern of tissues. Here, we show that during Drosophila wing development the loss of the tumor suppressor PTEN disrupts cell rearrangements by preventing the lengthening of newly formed junctions that become unstable and keep on rearranging. We demonstrate that the failure to lengthen and to stabilize is caused by the lack of a decrease of Myosin II and Rho-kinase concentration at the newly formed junctions. This defect results in a heterogeneous cortical contractility at cell junctions that disrupts regular hexagonal pattern formation. By identifying PTEN as a specific regulator of junction lengthening and stability, our results uncover how a homogenous distribution of cortical contractility along the cell cortex is restored during cell rearrangement to control the formation of epithelial cellular pattern. PMID:23707736

Bardet, Pierre-Luc; Guirao, Boris; Paoletti, Camille; Serman, Fanny; Léopold, Valentine; Bosveld, Floris; Goya, Yûki; Mirouse, Vincent; Graner, François; Bellaïche, Yohanns

2013-06-10

163

Tight junctions in human pancreatic duct epithelial cells  

PubMed Central

Tight junctions of the pancreatic duct are essential regulators of physiologic secretion of the pancreas and disruption of the pancreatic ductal barrier is known to contribute to the pathogenesis of pancreatitis and progression of pancreatic cancer. Various inflammatory mediators and carcinogens can trigger tight junction disassembly and disruption of the pancreatic barrier, however signaling events that mediates such barrier dysfunctions remain poorly understood. This review focuses on structure and regulation of tight junctions in normal pancreatic epithelial cells and mechanisms of junctional disruption during pancreatic inflammation and cancer. We will pay special attention to a novel model of human telomerase reverse transcriptase-transfected human pancreatic ductal epithelial cells and will describe the roles of major signaling molecules such as protein kinase C and c-Jun N-terminal kinase in formation and disassembly of the pancreatic ductal barrier. PMID:24665406

Kojima, Takashi; Yamaguchi, Hiroshi; Ito, Tatsuya; Kyuno, Daisuke; Kono, Tsuyoshi; Konno, Takumi; Sawada, Norimasa

2013-01-01

164

Vitamin-A-induced mucous metaplasia. An in vitro system for modulating tight and gap junction differentiation  

PubMed Central

Stratified squamous epithelia from 14-day chick embryo shank skin contain rare tight-junctional strands and only small gap junctions. Exposure of this tissue to retinoic acid (vitamin-A) (20 U/ml) in organ culture, however, induces mucous metaplasia, accompanied by tight- junction formation and gap-junction growth; untreated specimens continue to keratinize. To investigate sequential stages of junctional assembly and growth, we examined thin sections and freeze-fracture replicas at daily intervals for 3 days. During the metaplastic process, tight junctions assemble in midepidermal and upper regions, beginning on day 1 and becoming maximal on day 3. Two tight-junctional patterns could be tentatively identified as contributing to the emergence of fully formed zonulae occludentes: (a) the formation of individual ridges along the margins of gap junctions; (b) de novo generation of continuous ramifying strands by fusion of short strand segments and linear particulate aggregates near cellular apices. Gap junction enlargement, already maximal at day 1, occurs primarily three to four cell layers deep. Growth appears to occur by annexation of islands of 20-40 8.5-nm particles into larger lattices of islands separated by particle-free aisles. Eventually, a single gap junction may occupy much of the exposed membrane face in freeze-fractured tissue, but during apical migration of the cells such junctions disappear. The vitamin- A chick-skin system is presented as a responsive model for the controlled study of junction assembly. PMID:1245547

1976-01-01

165

An induced junction photovoltaic cell  

NASA Technical Reports Server (NTRS)

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

Call, R. L.

1974-01-01

166

Construction of a DNA four-way junction: Design and NMR spectroscopy  

Microsoft Academic Search

In 1964 Holliday postulated the formation of cruciform structures (four-way junctions) in duplex DNA as intermediate in genetic recombination. Since then, many biochemical and biophysical investigations were directed at solving questions concerning structural details of stable four-way junctions. Thus far, NMR spectroscopy played a minor part in these investigations on account of the minimum size of the molecule (expressed as

Cornelis Altona; Jeroen A. Pikkemaat

1995-01-01

167

Charge Tunneling Rates in Ultrasmall Junctions  

Microsoft Academic Search

1. Introduction 2. Description of the environment 3. Electron tunneling rates for single tunnel junctions 4. Examples of electromagnetic environments 5. Tunneling rates in Josephson junctions 6. Double junction and single electron transistor 7. Microscopic foundation

Gert-Ludwig Ingold; Yu. V. Nazarov

2005-01-01

168

High-speed carrier-depletion silicon Mach-Zehnder optical modulators with lateral PN junctions  

NASA Astrophysics Data System (ADS)

This paper presents new experimental data from a lateral PN junction silicon Mach-Zehnder optical modulator. Efficiencies in the 1.4V.cm to 1.9V.cm range are demonstrated for drive voltages between 0V and 6V. High speed operation up to 52Gbit/s is also presented. The performance of the device which has its PN junction positioned in the centre of the waveguide is then compared to previously reported data from a lateral PN junction device with the junction self-aligned to the edge of the waveguide rib. An improvement in modulation efficiency is demonstrated when the junction is positioned in the centre of the waveguide. Finally we propose schemes for achieving high modulation efficiency whilst retaining self-aligned formation of the PN junction.

Reed, Graham; Thomson, David; Gardes, Frederic; Hu, Youfang; Fedeli, Jean-Marc; Mashanovich, Goran

2014-12-01

169

Very large thermophase in ferromagnetic josephson junctions.  

PubMed

The concept of thermophase refers to the appearance of a phase gradient inside a superconductor originating from the presence of an applied temperature bias across it. The resulting supercurrent flow may, in suitable conditions, fully counterbalance the temperature-bias-induced quasiparticle current therefore preventing the formation of any voltage drop, i.e., a thermovoltage, across the superconductor. Yet, the appearance of a thermophase is expected to occur in Josephson-coupled superconductors as well. Here, we theoretically investigate the thermoelectric response of a thermally biased Josephson junction based on a ferromagnetic insulator. In particular, we predict the occurrence of a very large thermophase that can reach ?/2 across the contact for suitable temperatures and structure parameters; i.e., the quasiparticle thermal current can reach the critical current. Such a thermophase can be several orders of magnitude larger than that predicted to occur in conventional Josephson tunnel junctions. In order to assess experimentally the predicted very large thermophase, we propose a realistic setup realizable with state-of-the-art nanofabrication techniques and well-established materials, based on a superconducting quantum interference device. This effect could be of strong relevance in several low-temperature applications, for example, for revealing tiny temperature differences generated by coupling the electromagnetic radiation to one of the superconductors forming the junction. PMID:25723238

Giazotto, F; Heikkilä, T T; Bergeret, F S

2015-02-13

170

Very Large Thermophase in Ferromagnetic Josephson Junctions  

NASA Astrophysics Data System (ADS)

The concept of thermophase refers to the appearance of a phase gradient inside a superconductor originating from the presence of an applied temperature bias across it. The resulting supercurrent flow may, in suitable conditions, fully counterbalance the temperature-bias-induced quasiparticle current therefore preventing the formation of any voltage drop, i.e., a thermovoltage, across the superconductor. Yet, the appearance of a thermophase is expected to occur in Josephson-coupled superconductors as well. Here, we theoretically investigate the thermoelectric response of a thermally biased Josephson junction based on a ferromagnetic insulator. In particular, we predict the occurrence of a very large thermophase that can reach ? /2 across the contact for suitable temperatures and structure parameters; i.e., the quasiparticle thermal current can reach the critical current. Such a thermophase can be several orders of magnitude larger than that predicted to occur in conventional Josephson tunnel junctions. In order to assess experimentally the predicted very large thermophase, we propose a realistic setup realizable with state-of-the-art nanofabrication techniques and well-established materials, based on a superconducting quantum interference device. This effect could be of strong relevance in several low-temperature applications, for example, for revealing tiny temperature differences generated by coupling the electromagnetic radiation to one of the superconductors forming the junction.

Giazotto, F.; Heikkilä, T. T.; Bergeret, F. S.

2015-02-01

171

THE APPEARANCE AND STRUCTURE OF INTERCELLULAR CONNECTIONS DURING THE ONTOGENY OF THE RABBIT OVARIAN FOLLICLE WITH PARTICULAR REFERENCE TO GAP JUNCTIONS  

Microsoft Academic Search

Lanthanum tracer and freeze-fracture electron microscope techniques were used to study junctional complexes between granulosa cells during the differentiation of the rabbit ovarian follicle. For convenience we refer to cells encompassing the oocyte, before antrum and gap junction formation, as follicle cells. After the appearance of an antrum and gap junctions we call the cells granulosa cells. Maculae adherentes are

DAVID F. ALBERTINI; EVERETT ANDERSON

1974-01-01

172

The Junction Diode Basic Operation  

E-print Network

The Junction Diode Basic Operation The diode is fabricated of a semiconductor material, usually section of the diode. The junction is the dividing line between the n-type and p-type sides. Thermal the electric field sweeps them out. Figure 1: (a) Diode cross section. (b) Reverse biased diode. (c) Forward

Leach Jr.,W. Marshall

173

The Drosophila Claudin Kune-kune Is Required for Septate Junction Organization and Tracheal Tube Size Control  

PubMed Central

The vertebrate tight junction is a critical claudin-based cell–cell junction that functions to prevent free paracellular diffusion between epithelial cells. In Drosophila, this barrier is provided by the septate junction, which, despite being ultrastructurally distinct from the vertebrate tight junction, also contains the claudin-family proteins Megatrachea and Sinuous. Here we identify a third Drosophila claudin, Kune-kune, that localizes to septate junctions and is required for junction organization and paracellular barrier function, but not for apical-basal polarity. In the tracheal system, septate junctions have a barrier-independent function that promotes lumenal secretion of Vermiform and Serpentine, extracellular matrix modifier proteins that are required to restrict tube length. As with Sinuous and Megatrachea, loss of Kune-kune prevents this secretion and results in overly elongated tubes. Embryos lacking all three characterized claudins have tracheal phenotypes similar to any single mutant, indicating that these claudins act in the same pathway controlling tracheal tube length. However, we find that there are distinct requirements for these claudins in epithelial septate junction formation. Megatrachea is predominantly required for correct localization of septate junction components, while Sinuous is predominantly required for maintaining normal levels of septate junction proteins. Kune-kune is required for both localization and levels. Double- and triple-mutant combinations of Sinuous and Megatrachea with Kune-kune resemble the Kune-kune single mutant, suggesting that Kune-kune has a more central role in septate junction formation than either Sinuous or Megatrachea. PMID:20407131

Nelson, Kevin S.; Furuse, Mikio; Beitel, Greg J.

2010-01-01

174

Cadherin controls nectin recruitment into adherens junctions by remodeling the actin cytoskeleton.  

PubMed

The mechanism that coordinates activities of different adhesion receptors is poorly understood. We investigated this mechanism by focusing on the nectin-2 and E-cadherin adherens junction receptors. We found that, cadherin was not required for the basic process of nectin junction formation because nectin-2 formed junctions in cadherin-deficient A431D cells. Formation of nectin-2 junctions in these cells, however, became regulated by cadherin as soon as E-cadherin was re-expressed. E-cadherin recruited nectin-2 into adherens junctions, where both proteins formed distinct but tightly associated clusters. Live-cell imaging showed that the appearance of E-cadherin clusters often preceded that of nectin-2 clusters at sites of junction assembly. Inactivation of E-cadherin clustering by different strategies concomitantly suppressed the formation of nectin clusters. Furthermore, cadherin significantly increased the stability of nectin clusters, thereby making them resistant to the BC-12 antibody, which targets the nectin-2 adhesion interface. By testing different E-cadherin-?-catenin chimeras, we showed that the recruitment of nectin into chimera junctions is mediated by the actin-binding domain of ?-catenin. Our data suggests that E-cadherin regulates assembly of nectin junctions through ?-catenin-induced remodeling of the actin cytoskeleton around the cadherin clusters. PMID:25395582

Troyanovsky, Regina B; Indra, Indrajyoti; Chen, Chi-Shuo; Hong, Soonjin; Troyanovsky, Sergey M

2015-01-01

175

Bipolar Junction Transistors  

NSDL National Science Digital Library

All About Circuits is a website that â??provides a series of online textbooks covering electricity and electronics.â? Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Bipolar Junction Transistors, is the fourth chapter in Volume III â??Semiconductors. A few of the topics covered in this chapter include: The Transistor as a Switch, Active Mode Operation, and Input and Output Coupling. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

176

Disordered graphene Josephson junctions  

NASA Astrophysics Data System (ADS)

A tight-binding approach based on the Chebyshev-Bogoliubov-de Gennes method is used to describe disordered single-layer graphene Josephson junctions. Scattering by vacancies, ripples, or charged impurities is included. We compute the Josephson current and investigate the nature of multiple Andreev reflections, which induce bound states appearing as peaks in the density of states for energies below the superconducting gap. In the presence of single-atom vacancies, we observe a strong suppression of the supercurrent, which is a consequence of strong intervalley scattering. Although lattice deformations should not induce intervalley scattering, we find that the supercurrent is still suppressed, which is due to the presence of pseudomagnetic barriers. For charged impurities, we consider two cases depending on whether the average doping is zero, i.e., existence of electron-hole puddles, or finite. In both cases, short-range impurities strongly affect the supercurrent, similar to the vacancies scenario.

Muñoz, W. A.; Covaci, L.; Peeters, F. M.

2015-02-01

177

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

178

SIS junction reactance complete compensation  

SciTech Connect

SIS junction geometrical capacitance together with out of phase current I{sub kk} impedance component forms sufficient junction reactance X{sub SIS} = ({omega}C + B{sub Q}){sup {minus}1}. This paper suggests the way to resonate out both {omega}C and B{sub Q} by using additional identical SIS junction connected to the first through a long line impedance inverter and RF + DC biased symmetrically to the first. Pumped IV curves without quantum reactance and frequency impedance patterns of the system were calculated. Calculations demonstrated the presence of high and even negative induced dynamic resistance regions at high order quasiparticle steps for the case of SIS junction reactance complete compensation. The suggested method may be used in SIS mixers and detectors for a better RF matching.

Beletsky, V.Y.; Tarasov, M.A. (Inst. of Radio Engineering and Electronics, USSR Academy of Sciences, Marx Avenue 18 (SU))

1991-03-01

179

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, John (Berkeley, CA); Hilbert, Claude (Austin, TX); Hahn, Erwin L. (Berkeley, CA); Sleator, Tycho (Berkeley, CA)

1988-01-01

180

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

181

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

182

Expression of Functional Cell-Cell Channels from Cloned Rat Liver Gap Junction Complementary DNA  

NASA Astrophysics Data System (ADS)

An oocyte expression system was used to test the relation between a complementary DNA (cDNA) clone encoding the liver gap junction protein and cell-cell channels. Total liver polyadenylated messenger RNA injected into oocytes induced cell-cell channels between paired oocytes. This induction was blocked by simultaneous injection of antisense RNA transcribed from the gap junction cDNA. Messenger RNA selected by hybridization to the cDNA clone and translated in oocyte pairs yielded a higher junctional conductance than unselected liver messenger RNA. Cell-cell channels between oocytes were also formed when the cloned cDNA was expressed under the control of a heat-shock promoter. A concentration-dependent induction of channels was observed in response to injection with in vitro transcribed gap junction messenger RNA. Thus, the liver gap junction cDNA encodes a protein that is essential for the formation of functional cell-cell channels.

Dahl, G.; Miller, T.; Paul, D.; Voellmy, R.; Werner, R.

1987-06-01

183

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

184

Stability and structure of three-way DNA junctions containing unpaired nucleotides.  

PubMed Central

Non-paired nucleotides stabilize the formation of three-way helical DNA junctions. Two or more unpaired nucleotides located in the junction region enable oligomers ten to fifteen nucleotides long to assemble, forming conformationally homogeneous junctions, as judged by native gel electrophoresis. The unpaired bases can be present on the same strand or on two different strands. Up to five extra bases on one strand have been tested and found to produce stable junctions. The formation of stable structures is favored by the presence of a divalent cation such as magnesium and by high monovalent salt concentration. The order-disorder transition of representative three-way junctions was monitored optically in the ultraviolet and analyzed to quantify thermodynamically the stabilization provided by unpaired bases in the junction region. We report the first measurements of the thermodynamics of adding an unpaired nucleotide to a nucleic acid three-way junction. We find that delta delta G degrees (37 degrees C) = +0.5 kcal/mol for increasing the number of unpaired adenosines from two to three. Three-way junctions having reporter arms 40 base-pairs long were also prepared. Each of the three reporter arms contained a unique restriction site 15 base-pairs from the junction. Asymmetric complexes produced by selectively cleaving each arm were analyzed on native gels. Cleavage of the double helical arm opposite the strand having the two extra adenosines resulted in a complex that migrated more slowly than complexes produced by cleavage at either of the other two arms. It is likely that the strand containing the unpaired adenosines is kinked at an acute angle, forming a Y-shaped, rather than a T-shaped junction. Images PMID:2017361

Leontis, N B; Kwok, W; Newman, J S

1991-01-01

185

Interconverting conformations of slipped-DNA junctions formed by trinucleotide repeats affect repair outcome.  

PubMed

Expansions of (CTG)·(CAG) repeated DNAs are the mutagenic cause of 14 neurological diseases, likely arising through the formation and processing of slipped-strand DNAs. These transient intermediates of repeat length mutations are formed by out-of-register mispairing of repeat units on complementary strands. The three-way slipped-DNA junction, at which the excess repeats slip out from the duplex, is a poorly understood feature common to these mutagenic intermediates. Here, we reveal that slipped junctions can assume a surprising number of interconverting conformations where the strand opposite the slip-out either is fully base paired or has one or two unpaired nucleotides. These unpaired nucleotides can also arise opposite either of the nonslipped junction arms. Junction conformation can affect binding by various structure-specific DNA repair proteins and can also alter correct nick-directed repair levels. Junctions that have the potential to contain unpaired nucleotides are repaired with a significantly higher efficiency than constrained fully paired junctions. Surprisingly, certain junction conformations are aberrantly repaired to expansion mutations: misdirection of repair to the non-nicked strand opposite the slip-out leads to integration of the excess slipped-out repeats rather than their excision. Thus, slipped-junction structure can determine whether repair attempts lead to correction or expansion mutations. PMID:23339280

Slean, Meghan M; Reddy, Kaalak; Wu, Bin; Nichol Edamura, Kerrie; Kekis, Mariana; Nelissen, Frank H T; Aspers, Ruud L E G; Tessari, Marco; Schärer, Orlando D; Wijmenga, Sybren S; Pearson, Christopher E

2013-02-01

186

Superconducting tunnel junctions  

NASA Astrophysics Data System (ADS)

Superconducting tunnel junctions (STJ) are a class of cryogenic detectors that rely on the generation of free charge carriers by breaking Cooper pairs in a superconducting material with the use of absorbed photon energy. In an STJ, consisting of two superconducting films separated by a thin insulating barrier, the charge carriers can be detected through the tunnel-current pulse they produce if the STJ is under a finite voltage bias. The number of charge carriers generated is proportional to the energy of the absorbed photon, and, depending on the material of choice, ranges from several hundreds to a few thousand per electronvolt of photon energy. This allows STJs to be used as photon-counting detectors with intrinsic energy resolution over a wide energy band from the near infrared to well into the X-ray band. The operating temperature is typically at 10 % of the critical temperature Tc of the superconducting material and may range from 0.1 K to 1 K. Although they have not been deployed in space applications yet, they could well be envisaged as spectrometers with an energy-resolving power of several hundreds in the soft X-ray range, or as highly efficient order-sorting detectors in UV grating spectrographs. STJs can be used simultaneously as absorbers and read-out elements, or alternatively, if a larger sensitive area is required, two or more can be attached as read-out elements to a separate absorber. The state of the art performance comprises energy resolutions of 2 eV to 11 eV in the soft X-ray energy range from 0.4 keV to 5.9 keV, and of 0.1 eV to 0.2 eV in the near-infrared and visible range from 0.5 eV to 5 eV. Imaging arrays of >100 pixels of close-packed STJs have been made and operated in ground-based astronomical applications.

Martin, Didier D. E.; Verhoeve, Peter

187

Junction array carbon nanotube bolometer  

NASA Astrophysics Data System (ADS)

Vertically aligned arrays of multi-walled carbon nanotubes (MWNT forests) irradiated with low-intensity near-infrared laser exhibited bolometric response that became significant with decreasing temperature down from room to about 84 K. High responsivity of 42 V/W with signal bandwidth of about 2600 Hz was observed in the region with a surprisingly small temperature coefficient of resistance. This fact along with peculiar current dependences of material differential photoresistance can be explained by lifting Coulomb blockade in carbon nanotube junctions irradiated with light. A combination of significant bolometric response and nonlinear electrical transport are believed to be characteristic features of the nanostructured junction array system. Investigated material also revealed quite substantial noise with equivalent power of 3 * 10-6 WHz-1/2 that can be reduced by optimization of nanotube junction network in the forest structure.

Kozlov, Mikhail E.

2013-04-01

188

Triple junction distributions in polycrystals  

SciTech Connect

Recently, it has been demonstrated that some material properties can be enhanced by grain boundary engineering, i.e., the systematic modifications in the topology of the microstructure through thermomechanical processing. Experimental observations have shown that the microstructural parameter likely responsible for improved properties is the grain boundary character distribution (GBCD). It has been suggested that improvements in the fractions of special boundaries as defined by the coincident site lattice model (1) are necessary, but not fully sufficient to cause property improvements. For example, it has been observed that cracks propagating along interconnected networks of random grain boundaries can be arrested (2) when intersecting a triple junction where the remaining two pathways are special boundaries. Therefore, it is of interest to characterize microstructures in terms of the distributions of triple junction types. A simple method to describe a triple junction is by the types of grain boundaries intersecting at that junction [special vs. random, as described by the coincident site lattice (CSL) model]. The distribution of 0-CSL, 1-CSL, 2-CSL and 3-CSL triple junctions in the microstructure can then be plotted as a function of the fraction of special boundaries. Such data has been collected using orientation-imaging microscopy (OIM) (3--5) for oxygen-free-electronic (ofe)-Cu and Inconel 600 over a range of special fraction of grain boundaries. These results have been compared with theoretical models considering isolated triple junctions and invoking the {Sigma}-product rule (6) where {Sigma} is the inverse density of coincident lattice sites (7).

King, W.E.; Kumar, M.; Schwartz, A.J.

1999-07-01

189

Simple Electronic Analog of a Josephson Junction.  

ERIC Educational Resources Information Center

Demonstrates that an electronic Josephson junction analog constructed from three integrated circuits plus an external reference oscillator can exhibit many of the circuit phenomena of a real Josephson junction. Includes computer and other applications of the analog. (Author/SK)

Henry, R. W.; And Others

1981-01-01

190

All NbN tunnel junction fabrication  

NASA Technical Reports Server (NTRS)

The development of SIS tunnel junctions based on NbN for mixer applications in the submillimeter range is reported. The unique technological challenges inherent in the development of all refractory-compound superconductor-based tunnel junctions are highlighted. Current deposition and fabrication techniques are discussed, and the current status of all-NbN tunnel junctions is reported.

Leduc, H. G.; Khanna, S. K.; Stern, J. A.

1987-01-01

191

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

192

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

193

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

194

27 CFR 9.164 - River Junction.  

Code of Federal Regulations, 2014 CFR

...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

195

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

196

Tight and adherens junctions in the ovine uterus: differential regulation by pregnancy and progesterone.  

PubMed

In species with noninvasive implantation by conceptus trophectoderm, fetal/maternal communications occur across the endometrial epithelia. The present studies identified changes in junctional complexes in the ovine endometrium that regulate paracellular trafficking of water, ions, and other molecules, and the secretory capacity of the uterine epithelia. Distinct temporal and spatial alterations in occludin, tight junction protein 2, and claudin 1-4 proteins were observed in the endometrium of cyclic and early pregnant ewes. Dynamic changes in tight junction formation were characterized by an abundance of tight junction proteins on d 10 of the estrous cycle and pregnancy that substantially decreased by d 12. Early progesterone administration advanced conceptus development on d 9 and 12 that was associated with loss of tight-junction-associated proteins. Pregnancy increased tight-junction-associated proteins between d 14-16. Cadherin 1 and beta-catenin, which form adherens junctions, were abundant in the endometrial glands, but decreased after d 10 of pregnancy in the luminal epithelium and then increased by d 16 with the onset of implantation. Results support the ideas that progesterone elicits transient decreases in tight and adherens junctions in the endometrial luminal epithelium between d 10-12 that increases selective serum and tissue fluid transudation to enhance blastocyst elongation, which is subsequently followed by an increase in tight and adherens junctions between d 14-16 that may be required for attachment and adherence of the trophectoderm for implantation. The continuous presence of tight and adherens junctions in the uterine glands would allow for vectorial secretion of trophic substances required for conceptus elongation and survival. PMID:17478549

Satterfield, M Carey; Dunlap, Kathrin A; Hayashi, Kanako; Burghardt, Robert C; Spencer, Thomas E; Bazer, Fuller W

2007-08-01

197

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

198

Promoting RNA helical stacking via A-minor junctions  

PubMed Central

RNA molecules take advantage of prevalent structural motifs to fold and assemble into well-defined 3D architectures. The A-minor junction is a class of RNA motifs that specifically controls coaxial stacking of helices in natural RNAs. A sensitive self-assembling supra-molecular system was used as an assay to compare several natural and previously unidentified A-minor junctions by native polyacrylamide gel electrophoresis and atomic force microscopy. This class of modular motifs follows a topological rule that can accommodate a variety of interchangeable A-minor interactions with distinct local structural motifs. Overall, two different types of A-minor junctions can be distinguished based on their functional self-assembling behavior: one group makes use of triloops or GNRA and GNRA-like loops assembling with helices, while the other takes advantage of more complex tertiary receptors specific for the loop to gain higher stability. This study demonstrates how different structural motifs of RNA can contribute to the formation of topologically equivalent helical stacks. It also exemplifies the need of classifying RNA motifs based on their tertiary structural features rather than secondary structural features. The A-minor junction rule can be used to facilitate tertiary structure prediction of RNAs and rational design of RNA parts for nanobiotechnology and synthetic biology. PMID:20876687

Geary, Cody; Chworos, Arkadiusz; Jaeger, Luc

2011-01-01

199

Gap Junctions and Connexin Hemichannels Underpin Haemostasis and Thrombosis  

PubMed Central

Background Connexins are a widespread family of membrane proteins that assemble into hexameric hemichannels, also known as connexons. Connexons regulate membrane permeability in individual cells or couple between adjacent cells to form gap junctions and thereby provide a pathway for regulated intercellular communication. We have now examined the role of connexins in platelets, blood cells that circulate in isolation, but upon tissue injury adhere to each other and the vessel wall to prevent blood loss and facilitate wound repair. Methods and Results We report the presence of connexins in platelets, notably connexin37, and that the formation of gap junctions within platelet thrombi is required for the control of clot retraction. Inhibition of connexin function modulated a range of platelet functional responses prior to platelet-platelet contact, and reduced laser induced thrombosis in vivo in mice. Deletion of the Cx37 gene (Gja4) in transgenic mice reduced platelet aggregation, fibrinogen binding, granule secretion and clot retraction indicating an important role for Cx37 hemichannels and gap junctions in platelet thrombus function. Conclusions Together, these data demonstrate that platelet gap junctions and hemichannels underpin the control of haemostasis and thrombosis and represent potential therapeutic targets. PMID:22528526

Vaiyapuri, Sakthivel; Jones, Chris I.; Sasikumar, Parvathy; Moraes, Leonardo A.; Munger, Stephanie J.; Wright, Joy R.; Ali, Marfoua S.; Sage, Tanya; Kaiser, William J.; Tucker, Katherine L.; Stain, Christopher J.; Bye, Alexander P.; Jones, Sarah; Oviedo-Orta, Ernesto; Simon, Alexander M.; Mahaut-Smith, Martyn P.; Gibbins, Jonathan M.

2012-01-01

200

Metal-semiconductor junction of graphene nanoribbons  

NASA Astrophysics Data System (ADS)

Patterned all-graphene circuits, in which semiconducting graphene nanoribbon (GNR) device channels are connected by metallic GNR interconnects, raise possibilities for carbon-based electronics. The properties of GNR metal-semiconductor junctions, which are the key elements in all-graphene circuits, are studied by atomistic simulations. The junction conductance strongly depends on the atomistic features of the access geometry from the metallic GNR to the semiconducting GNR. Highly localized states exist at the junction edges, which can result in sharp metal-induced gap states. A defect of a single lattice vacancy can significantly increase rather than decrease the junction conductance for certain junction geometries.

Hong, Seokmin; Yoon, Youngki; Guo, Jing

2008-02-01

201

Signaling the Junctions in Gut Epithelium  

NSDL National Science Digital Library

This Perspective summarizes recent developments in our understanding of the signaling pathways involved in the regulation of epithelial cell adhesion in the gut. The role of phosphatidylinositol 3-kinase signaling in the modulation of adherens junctions, and the connections between tight junctions and nuclear transcription factors, are discussed. The effect of gastrins on adherens and tight junctions is presented as an example of the regulation of adhesion by growth factors. The consequences of dysregulation of adherens junctions and tight junctions for human pathology are also considered.

Frederic Hollande (CNRS France; Functional Genomics Institute (IGF) and Cellular and Molecular Oncology Department REV)

2005-03-29

202

A membrane fusion protein ?SNAP is a novel regulator of epithelial apical junctions.  

PubMed

Tight junctions (TJs) and adherens junctions (AJs) are key determinants of the structure and permeability of epithelial barriers. Although exocytic delivery to the cell surface is crucial for junctional assembly, little is known about the mechanisms controlling TJ and AJ exocytosis. This study was aimed at investigating whether a key mediator of exocytosis, soluble N-ethylmaleimide sensitive factor (NSF) attachment protein alpha (?SNAP), regulates epithelial junctions. ?SNAP was enriched at apical junctions in SK-CO15 and T84 colonic epithelial cells and in normal human intestinal mucosa. siRNA-mediated knockdown of ?SNAP inhibited AJ/TJ assembly and establishment of the paracellular barrier in SK-CO15 cells, which was accompanied by a significant down-regulation of p120-catenin and E-cadherin expression. A selective depletion of p120 catenin effectively disrupted AJ and TJ structure and compromised the epithelial barrier. However, overexpression of p120 catenin did not rescue the defects of junctional structure and permeability caused by ?SNAP knockdown thereby suggesting the involvement of additional mechanisms. Such mechanisms did not depend on NSF functions or induction of cell death, but were associated with disruption of the Golgi complex and down-regulation of a Golgi-associated guanidine nucleotide exchange factor, GBF1. These findings suggest novel roles for ?SNAP in promoting the formation of epithelial AJs and TJs by controlling Golgi-dependent expression and trafficking of junctional proteins. PMID:22485163

Naydenov, Nayden G; Brown, Bryan; Harris, Gianni; Dohn, Michael R; Morales, Victor M; Baranwal, Somesh; Reynolds, Albert B; Ivanov, Andrei I

2012-01-01

203

Comparison of pre-junctional ?-adrenoceptors at the neuromuscular junction with vascular post-junctional ?-receptors in cat skeletal muscle  

PubMed Central

1 Activation of pre-junctional ?-adrenoceptors at the skeletal neuromuscular junction enhances acetylcholine release whereas activation of such receptors at autonomic nerve endings inhibits transmitter output. In the present study the characteristics of pre-junctional ?-adrenoceptors at motor nerve terminals have been compared with post-junctional (vascular) ?-adrenoceptors in the cat hind limb. 2 Reversal of partial (+)-tubocurarine blockade of contractions of the tibialis anterior muscle was used to monitor pre-junctional activity and increases in hindlimb vascular resistance to assess post-junctional actions at ?-adrenoceptors. 3 Responses to intra-arterial injections of noradrenaline, adrenaline, phenylephrine, oxymetazoline, methoxamine and clonidine were monitored. Dose-response lines for all the compounds except clonidine were parallel. The latter agent produced only weak and inconsistent effects. 4 Ratios of the doses of the agents required to produce pre- and post-junctional effects indicated that oxymetazoline and adrenaline possessed some preferential activity at post-junctional sites, whereas the remaining agents were non-selective in their actions. If dose-ratios with respect to noradrenaline were compared at the two sites none of the compounds possessed a marked degree of selectivity. 5 In the presence of phentolamine or tolazoline, dose-response curves to the pre- and post-junctional effects of phenylephrine were shifted to a similar extent. Thymoxamine showed preferential activity as a pre-junctional ?-receptor antagonist. 6 In comparing the results of this study with those of other authors, it is apparent that there are marked differences in the characteristics of pre-junctional ?-receptors at the skeletal neuromuscular junction and at autonomic nerve endings. The pre- and post-junctional ?-receptors in skeletal muscle show less divergence. PMID:216453

Malta, E.; McPherson, G.A.; Raper, C.

1979-01-01

204

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

205

Gating of gap junction channels.  

PubMed Central

Gap junctional conductance ( gj ) in various species is gated by voltage and intracellular pH (pHi). In amphibian embryos, gj is reduced to half by a 14 mV transjunctional voltage ( Vj ), a change that in fish embryo requires approximately 28 mV. Crayfish septate axon and pairs of dissociated rat myocytes show no voltage dependence of gj over a range of Vj greater than +/- 50 mV. In fish and amphibian blastomeres , gj is steeply decreased by decrease in pHi (n, Hill coefficient: 4.5) and the apparent pKH (7.3) is in the physiological range. In crayfish septate axon the pKH is lower (6.7) and the curve is less steep (n = 2.7). Rises in cytoplasmic Ca can also decrease gj but much higher concentrations are required (greater than 0.1 mM in fish blastomeres). Voltage and pH gates on gap junctions in amphibian embryos appear independent. In squid blastomeres pH gates exhibit some sensitivity to potential, both transjunctional and between inside and outside. A pharmacology of gap junctions is being developed: certain agents block gj directly (aldehydes, alcohols, NEM in crayfish); others block by decreasing pHi (esters that are hydrolyzed by intrinsic esterases, NEM in vertebrates, and, as in the experiments demonstrating the effect of pHi, weak acids). Certain agents block pH sensitivity without affecting voltage dependence (retinoic acid, glutaraldehyde, EEDQ), further indicating separateness of pH and voltage gates. These studies demonstrate a dynamics of gap junctional conductance and variability in gating in a series of possibly homologous membrane channels. Images FIGURE 6 PMID:6324905

Spray, D C; White, R L; de Carvalho, A C; Harris, A L; Bennett, M V

1984-01-01

206

Defect-Free Junction TFT for Improving Reliability under Hot Carrier Stress  

NASA Astrophysics Data System (ADS)

A new polycrystalline silicon thin film transistor (poly-Si TFTs) called 'Defect-Free Junction TFT (DFJ-TFT)', which exhibits improved stability under hot carrier stress, has been proposed and fabricated. In order to remove residual junction defects due to ion implantation, source/drain doping was carried out prior to gate formation. During excimer laser annealing (ELA), large lateral grains are grown near the junction of the proposed TFT due to the different melting conditions between implanted source/drain region and non-implanted channel region. Our TEM image shows that there are large grains near the source/drain junction instead of residual implanted damage. The DFJ-TFT exhibits improved reliability compared with conventional TFT under hot carrier stress.

Jung, Sang-Hoon; Shin, Hee-Sun; Han, Min-Koo

2004-01-01

207

Gap Junctional Communication in Morphogenesis  

PubMed Central

Gap junctions permit the direct passage of small molecules from the cytosol of one cell to that of its neighbor, and thus form a system of cell-cell communication that exists alongside familiar secretion/receptor signaling. Because of the rich potential for regulation of junctional conductance, and directional and molecular gating (specificity), gap junctional communication (GJC) plays a crucial role in many aspects of normal tissue physiology. However, the most exciting role for GJC is in the regulation of information flow that takes place during embryonic development, regeneration, and tumor progression. The molecular mechanisms by which GJC establishes local and long-range instructive morphogenetic cues are just beginning to be understood. This review summarizes the current knowledge of the involvement of GJC in the patterning of both vertebrate and invertebrate systems and discusses in detail several morphogenetic systems in which the properties of this signaling have been molecularly characterized. One model consistent with existing data in the fields of vertebrate left-right patterning and anterior-posterior polarity in flatworm regeneration postulates electrophoretically-guided movement of small molecule morphogens through long-range GJC paths. The discovery of mechanisms controlling embryonic and regenerative GJC-mediated signaling, and identification of the downstream targets of GJC-permeable molecules, represent exciting next areas of research in this fascinating field. PMID:17481700

Levin, Michael

2007-01-01

208

Low-high junction theory applied to solar cells  

NASA Technical Reports Server (NTRS)

Recent use of alloying techniques for rear contact formation has yielded a new kind of silicon solar cell, the back surface field (BSF) cell, with abnormally high open circuit voltage and improved radiation resistance. Several analytical models for open circuit voltage based on the reverse saturation current are formulated to explain these observations. The zero SRV case of the conventional cell model, the drift field model, and the low-high junction (LHJ) model can predict the experimental trends. The LHJ model applies the theory of the low-high junction and is considered to reflect a more realistic view of cell fabrication. This model can predict the experimental trends observed for BSF cells. Detailed descriptions and derivations for the models are included. The correspondences between them are discussed. This modeling suggests that the meaning of minority carrier diffusion length measured in BSF cells be reexamined.

Godlewski, M. P.; Baraona, C. R.; Brandhorst, H. W., Jr.

1973-01-01

209

Do conformational biases of simple helical junctions influence RNA folding stability and specificity?  

SciTech Connect

Structured RNAs must fold into their native structures and discriminate against a large number of alternative ones, an especially difficult task given the limited information content of RNA's nucleotide alphabet. The simplest motifs within structured RNAs are two helices joined by nonhelical junctions. To uncover the fundamental behavior of these motifs and to elucidate the underlying physical forces and challenges faced by structured RNAs, we computationally and experimentally studied a tethered duplex model system composed of two helices joined by flexible single- or double-stranded polyethylene glycol tethers, whose lengths correspond to those typically observed in junctions from structured RNAs. To dissect the thermodynamic properties of these simple motifs, we computationally probed how junction topology, electrostatics, and tertiary contact location influenced folding stability. Small-angle X-ray scattering was used to assess our predictions. Single- or double-stranded junctions, independent of sequence, greatly reduce the space of allowed helical conformations and influencing the preferred location and orientation of their adjoining helices. A double-stranded junction guides the helices along a hinge-like pathway. In contrast, a single-stranded junction samples a broader set of conformations and has different preferences than the double-stranded junction. In turn, these preferences determine the stability and distinct specificities of tertiary structure formation. These sequence-independent effects suggest that properties as simple as a junction's topology can generally define the accessible conformational space, thereby stabilizing desired structures and assisting in discriminating against misfolded structures. Thus, junction topology provides a fundamental strategy for transcending the limitations imposed by the low information content of RNA primary sequence.

Chu, Vincent B.; Lipfert, Jan; Bai, Yu; Pande, Vijay S.; Doniach, Sebastian; Herschlag, Daniel; (Stanford); (Houston); (DUT)

2010-02-11

210

Modulated microwave absorption spectra from Josephson junctions on a scratched niobium wire  

SciTech Connect

Modulated microwave absorption (MMA) spectra from Josephson junction formations on a scratched Nb wire have been studied at 9.3 GHz and 4 K. The peak-to-peak separation, {delta}H of the Josephson lines was found to vary linearly with P{sup 1/2}, where P is the applied microwave power, in contrast to a recent interpretation of junction formation in pressed lead pieces by Rubins, Drumheller, and Trybula. The interpretation of the MMA data on Nb are given in terms of the theory of Vichery, Beuneu, and Lejay for superconducting loops containing weak links. {copyright} {ital 1997} {ital The American Physical Society}

Rubins, R.S. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)] [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States); [University of Texas at Arlington, Box 19059, Arlington, Texas 76019 (United States); Hutton, S.L.; Ravindran, K.; Subbaraman, K.; Drumheller, J.E. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)] [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)

1997-05-01

211

Fabrication of Tunnel Junctions For Direct Detector Arrays With Single-Electron Transistor Readout Using Electron-Beam Lithography  

NASA Technical Reports Server (NTRS)

This paper will describe the fabrication of small aluminum tunnel junctions for applications in astronomy. Antenna-coupled superconducting tunnel junctions with integrated single-electron transistor readout have the potential for photon-counting sensitivity at sub-millimeter wavelengths. The junctions for the detector and single-electron transistor can be made with electron-beam lithography and a standard self-aligned double-angle deposition process. However, high yield and uniformity of the junctions is required for large-format detector arrays. This paper will describe how measurement and modification of the sensitivity ratio in the resist bilayer was used to greatly improve the reliability of forming devices with uniform, sub-micron size, low-leakage junctions.

Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Rhee, K. W.; Teufel, J.; Schoelkopf, R. J.

2002-01-01

212

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

213

Thermal activation of superconducting Josephson junctions  

E-print Network

Superconducting quantum circuits (SQCs) are being explored as model systems for scalable quantum computing architectures. Josephson junctions are extensively used in superconducting quantum interference devices (SQUIDs) ...

Devalapalli, Aditya P. (Aditya Prakash)

2007-01-01

214

mode junction Full-adder design using photonic crystal mode junction structure  

E-print Network

mode junction Full-adder design using photonic crystal mode junction structure , , Abstract We propose a photonic crystal, all-optical full adder based on the mode junction structure. Utilizing non-degenerate orthogonal modes of a tri-atom optical molecule under the effect of Kerr

Park, Namkyoo

215

Interaction of Junctional Adhesion Molecule with the Tight Junction Components ZO-1, Cingulin, and Occludin  

Microsoft Academic Search

Junctional adhesion molecule (JAM) is an integral membrane protein that has been reported to colocalize with the tight junction molecules occludin, ZO-1, and cingulin. However, evidence for the association of JAM with these molecules is missing. Transfection of Chinese hamster ovary cells with JAM (either alone or in combi- nation with occludin) resulted in enhanced junctional localization of both endogenous

Gianfranco Bazzoni; Ofelia Maria Martinez-Estrada; Fabrizio Orsenigo; Michelangelo Cordenonsi; Sandra Citi; Elisabetta Dejana

2000-01-01

216

PROXIMITY EFFECT TUNNEL JUNCTIONS WITH BARRIERS FORMED FROM AMORPHOUS ALLOYS R.B. Laibowitz, C.C. Tsuei, P. Chaudhari, S.I. Raider, R. Drake and J.M. Viggiano  

E-print Network

for barrier formation, high quality tunnel junctions could be fabricated. In this instance, high quality, it was not pos- sible to obtain high current densities i.e. low junc- tion resistance with this barrier formationPROXIMITY EFFECT TUNNEL JUNCTIONS WITH BARRIERS FORMED FROM AMORPHOUS ALLOYS R.B. Laibowitz, C

Boyer, Edmond

217

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

218

Junction angles in drainage networks  

NASA Astrophysics Data System (ADS)

A theoretical model relating the junction angle of a tributary in a drainage network to its own Shreve magnitude and the Shreve magnitude of the stream into which it flows is developed and verified using published data (including Landsat maps) on U.S. networks with different underlying rock types, relief, and basin lengths. Good agreement is found, and a tendency for the slopes of individual network links to evolve toward graded longitudinal profiles as the network approaches an equilibrium (graded') planimetric pattern is noted. The differences between the network patterns predicted by the model and those observed on Mars are indicated, confirming the results of Pieri (1979, 1980).

Pieri, D. C.

1984-08-01

219

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

220

Proliferation of sharp kinks on cosmic (super)string loops with junctions  

SciTech Connect

Motivated by their effect on the gravitational wave signal emitted by cosmic strings, we study the dynamics of kinks on strings of different tensions meeting at junctions. The propagation of a kink through a Y junction leads to the formation of three 'daughter' kinks. Assuming a uniform distribution of the incoming wave vectors at the junction, we find there is a significant region of configuration space in which the sharpness of at least one of the daughter kinks is enhanced relative to the sharpness of the initial kink. For closed loops with junctions we show this leads to an exponential growth in time of very sharp kinks. Using numerical simulations of realistic, evolving cosmic string loops with junctions to calculate the distribution of kink amplitudes as a function of time, we show that loops of this kind typically develop several orders of magnitude of very sharp kinks before the two junctions collide. This collision, or other effects such as gravitational backreaction, may end the proliferation.

Binetruy, P.; Bohe, A.; Hertog, T.; Steer, D. A. [APC, 10 rue Alice Domon et Leonie Duquet, 75205 Paris Cedex 13 (France) and Universite Paris-Diderot, CNRS/IN2P3, CEA/IRFU and Observatoire de Paris (France)

2010-10-15

221

Anti-breast Cancer Agents, Quinolines, Targeting Gap Junction  

PubMed Central

Cancer cells exhibit many defects in cell communication that contribute to the loss of tissue homeostasis (excess cell proliferation, invasion, and metastasis). The process of cancer formation causes a disruption in cell homeostasis, affecting the ability to respond to extracellular signals, as well as triggering some intracellular events which alter gap junctional intercellular communication (GJIC). Previous research has shown that the first two generations of substituted quinolines have anti-cancer effects in human breast cancer cells. This report presents the synthesis and bioactivities of third generation substituted quinolines. Scrape load/dye transfer studies showed that 100 nM of PQ15, a third generation substituted quinoline, causes a 4.5-fold increase of gap junction activity in T47D breast cancer cells. Furthermore, a significant decrease of cell proliferation and viability was observed in the presence of 200 nM PQ15 compared to control. The expression of ?-survivin was reduced to <18% in the treatment of 100 nM PQ15 compared to control without treatment or solvent. Alpha-survivin expression is upregulated in human cancers and associated with resistance to chemotherapy, suggesting that ?-survivin prolongs the survival of cancer cells. Thus, it has been shown that substituted quinolines stimulate gap junction activity, decrease alpha survivin expression, and subsequently inhibit cancer cell growth. Our findings demonstrate that PQ15 has a promising role in exerting anti-cancer activity in human breast cancer cells. PMID:21801150

Bernzweig, Julie; Heiniger, Brian; Prasain, Keshar; Lu, Jianyu; Hua, Duy H.; Nguyen, Thu A.

2011-01-01

222

Magnetoresistance in Boron Carbide junctions  

NASA Astrophysics Data System (ADS)

The properties of thin insulator layers are crucial to the performance of magnetic tunnel junctions. Commercial requirements are a device with a high tunnel magnetoresistance (TMR) with low cost and high stability. At present the vast majority of barriers are made from amorphous Al2O3 and crystalline MgO. The TMR value depends not only on the spin-dependent electronic structure of the electrodes, but on the metal-insulator interface. Oxide-type barriers may suffer from local vacancies and other type of defects, resulting in oxygen diffusion, making the TMR value unstable with time. We present TMR results obtained on a non-oxide barrier, boron carbide (B10C2) for applications in magnetic tunnel junctions. This low Z inorganic material can be grown by plasma enhanced chemical vapor deposition (PECVD) without pinholes in the ultra thin film regime. PECVD grown boron carbide is an excellent dielectric with resistivities in the range of 10^7 ohm-cm, with a band gap that can be adjusted from 0.7 eV to 1.9 eV by altering the boron to carbon ratio and to band gap values well above 2.7 eV by adding phosphorus. This creates a unique opportunity for experimental study of a broad spectrum of phenomena, related to the dielectric properties of the barrier.

Day, Ellen; Sokolov, A.; Baruth, A.; Robertson, B. W.; Adenwalla, S.

2007-03-01

223

Occludin is a functional component of the tight junction.  

PubMed

Occludin's role in mammalian tight junction activity was examined by 'labeling' the occludin pool with immunologically detectable chick occludin. This was accomplished by first transfecting MDCK cell with the Lac repressor gene. HygR clones were then transfected with chick occludin cDNA inserted into a Lac operator construct. The resulting HygR/NeoR clones were plated on porous inserts and allowed to form tight junctions. Once steady state transepithelial electrical resistance was achieved, isopropyl- beta-D-thiogalactoside was added to induce chick occludin expression. Confocal laser scanning microscopy of monolayers immunolabeled with Oc-2 monoclonal antibody revealed that chick occludin localized precisely to the preformed tight junctions. When sparse cultures were maintained in low Ca2+ medium, chick occludin and canine ZO-1 co-localized to punctate sites in the cytoplasm suggesting their association within the same vesicular structures. In low calcium medium both proteins also co-localized to contact sites between occasional cell pairs, where a prominent bar was formed at the plasma membrane. Chick occludin was detectable by western blot within two hours of adding isopropyl- beta-D-thiogalactoside to monolayers that had previously achieved steady state transepithelial electrical resistance; this coincided with focal immunofluorescence staining for chick occludin at the cell membrane of some cells. A gradual rise in transepithelial electrical resistance, above control steady state values, began five hours after addition of the inducing agent reaching new steady state values, which were 30-40% above baseline, 31 hours later. Upon removal of isopropyl- beta-D-thiogalactoside chick occludin expression declined slowly until it was no longer detected in western blots 72 hours later; transepithelial electrical resistance also returned to baseline values during this time. While densitometric analysis of western blots indicated that the presence of chick occludin had no detectable effect on E-cadherin or ZO-1 expression, the possibility cannot be excluded that ZO-1 might be a limiting factor in the expression of chick occludin at the cell surface. To test whether expression of chick occludin affected the process of tight junction assembly, monolayers in low Ca2+ medium were treated with isopropyl- beta-D-thiogalactoside for 24 or 48 hours, before Ca2+ was added to stimulate tight junction assembly. Chick occludin did not alter the rate at which transepithelial electrical resistance developed, however, steady state values were 30-40% above control monolayers not supplemented with the inducing agent. By freeze fracture analysis, the number of parallel tight junction strands shifted from a mode of three in controls to four strands in cells expressing chick occludin and the mean width of the tight junction network increased from 175 +/- 11 nm to 248 +/- 16 nm. Two days after plating confluent monolayers that were induced to express chick occludin, mannitol flux was reduced to a variable degree relative to control monolayers. With continued incubation with the inducing agent, mannitol flux increased on day 11 to 50%, and TER rose to 45% above controls. Both of these changes were reversible upon removal of isopropyl- beta-D-thiogalactoside. These data are consistent with the notion that occludin contributes to the electrical barrier function of the tight junction and possibly to the formation of aqueous pores within tight junction strands. PMID:8886979

McCarthy, K M; Skare, I B; Stankewich, M C; Furuse, M; Tsukita, S; Rogers, R A; Lynch, R D; Schneeberger, E E

1996-09-01

224

Superradiance and superfluorescence in Josephson junction arrays  

NASA Astrophysics Data System (ADS)

Bonifacio et al. (1982) have discussed analogies between free-electron lasers and Josephson junctions, taking into account as basis a simple Hamiltonian model. Bonifacio and Casagrande (1983) have extended the model in the case of free-electron lasers to include dissipative effects. The present investigation is concerned with the introduction of a simple dissipative model for the dynamics of an array of Josephson junctions. The model involves N identical junctions connected in series and interacting with one resonant cavity electromagnetic mode of frequency Omega. Dissipation is taken into account by means of two mechanisms, including the losses of the radiation field and the dephasing (coherence loss) of the junctions. It is found that in a coherent array the ac Josephson oscillations in all the junctions occur with the same phase for a given frequency.

Bonifacio, R.; Casagrande, F.; Milani, M.

1984-04-01

225

Tunneling magnetothermopower in magnetic tunnel junctions  

NASA Astrophysics Data System (ADS)

Thermally induced spin-dependent transport across magnetic tunnel junctions (MTJs) is theoretically investigated. We analyze the thermal analog of Slonczewski's model (as well as its limiting case—Julliere's model) of tunneling magnetoresistance and obtain analytical expressions for the junction thermopower and the tunneling magnetothermopower (TMT). The analytical model is tested numerically for the special case of an Al2O3-based MTJ, for which we analyze the dependence of the thermopower and TMT on the relative magnetization orientations, as well as on the barrier height and thickness. We show that at a certain barrier height TMT vanishes, separating the region of positive and negative TMT. As its electrical prototype, this thermal spin transport model should serve as a phenomenological benchmark for analyzing experimental and first-principles calculations of thermopower in magnetic tunnel junctions. The analytical expressions can be used as a first estimate of the magnetothermopower of the junctions using ab initio band structure data of the junction ferromagnets.

López-Monís, Carlos; Matos-Abiague, Alex; Fabian, Jaroslav

2014-02-01

226

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

227

Parallel and antiparallel Holliday junctions differ in structure and stability.  

PubMed

Two Holliday junction analogs, JA and JP, containing identical base-paired arms have been constructed from oligonucleotides. The former is constrained to adopt an antiparallel Sigal-Alberts structure, and the latter a parallel structure, by means of single strand d(T)9 tethers. We evaluate here the free energy difference between JA and JP using two different methods. One is a direct measurement of the ratio of the equilibrium constants for formation of branched structures from intact duplexes using one labeled strand and a competition assay. The second method estimates the difference in stability from the difference in thermal denaturation temperatures of JA and JP, using urea to shift the tm of the complexes. Both methods reveal a small free energy difference between the two complexes: JA is more stable than JP by -1.1(+/- 0.4) kcal (mol junction)-1, at 25 degrees C, 5 mM-Mg2+, from the first method, and by -1.6(+/- 0.3) kcal (mol junction)-1, according to the second. DNase I and the resolvase, endonuclease I from phage T7, cleave JA differently from JP in the vicinity of the branch, indicating that the structures of these two models differ at this site. Diethyl pyrocarbonate also reveals a difference in the major grooves. Comparison of the scission patterns of JA and JP by the reactive chemical probes methidium-propyl-EDTA..Fe(II), [MPE.Fe(II)] and Cu(I)-[o-phenanthroline]2,[(OP)2Cu(I)], indicates that in both cases the branch point is a site of enhanced binding for drugs, as it is in the untethered four-arm junction containing the same core sequence at the branch. PMID:1942060

Lu, M; Guo, Q; Seeman, N C; Kallenbach, N R

1991-10-20

228

Nectin and junctional adhesion molecule are critical cell adhesion molecules for the apico-basal alignment of adherens and tight junctions in epithelial cells.  

PubMed

Tight junctions (TJs) and adherens junctions (AJs) form an apical junctional complex at the apical side of the lateral membranes of epithelial cells, in which TJs are aligned at the apical side of AJs. Many cell adhesion molecules (CAMs) and cell polarity molecules (CPMs) cooperatively regulate the formation of the apical junctional complex, but the mechanism for the alignment of TJs at the apical side of AJs is not fully understood. We developed a cellular system with which epithelial-like TJs and AJs were reconstituted in fibroblasts and analyzed the cooperative roles of CAMs and CPMs. We exogenously expressed various combinations of CAMs and CPMs in fibroblasts that express negligible amounts of these molecules endogenously. In these cells, the nectin-based cell-cell adhesion was formed at the apical side of the junctional adhesion molecule (JAM)-based cell-cell adhesion, and cadherin and claudin were recruited to the nectin-3- and JAM-based cell-cell adhesion sites to form AJ-like and TJ-like domains, respectively. This inversed alignment of the AJ-like and TJ-like domains was reversed by complementary expression of CPMs Par-3, atypical protein kinase C, Par-6, Crb3, Pals1 and Patj. We describe the cooperative roles of these CAMs and CPMs in the apico-basal alignment of TJs and AJs in epithelial cells. PMID:24112238

Yamada, Tomohiro; Kuramitsu, Kaori; Rikitsu, Etsuko; Kurita, Souichi; Ikeda, Wataru; Takai, Yoshimi

2013-11-01

229

Role of aPKC Isoforms and Their Binding Partners Par3 and Par6 in Epidermal Barrier Formation  

Microsoft Academic Search

The skin water barrier, essential for terrestrial life, is formed by a multilayered stratifying epithelium, which shows a polarized distribution of both differentiation and intercellular junction markers. Recently, several reports showed the crucial importance of tight junctions for the in vivo water barrier function of the skin. In simple epithelial cells, intercellular junction formation is closely coupled to the establishment

Iris Helfrich; Annika Schmitz; Paola Zigrino; Christian Michels; Ingo Haase; André le Bivic; Michael Leitges; Carien M Niessen

2007-01-01

230

Nonparametric generalized belief propagation based on pseudo-junction tree for cooperative localization in wireless networks  

NASA Astrophysics Data System (ADS)

Non-parametric belief propagation (NBP) is a well-known message passing method for cooperative localization in wireless networks. However, due to the over-counting problem in the networks with loops, NBP's convergence is not guaranteed, and its estimates are typically less accurate. One solution for this problem is non-parametric generalized belief propagation based on junction tree. However, this method is intractable in large-scale networks due to the high-complexity of the junction tree formation, and the high-dimensionality of the particles. Therefore, in this article, we propose the non-parametric generalized belief propagation based on pseudo-junction tree (NGBP-PJT). The main difference comparing with the standard method is the formation of pseudo-junction tree, which represents the approximated junction tree based on thin graph. In addition, in order to decrease the number of high-dimensional particles, we use more informative importance density function, and reduce the dimensionality of the messages. As by-product, we also propose NBP based on thin graph (NBP-TG), a cheaper variant of NBP, which runs on the same graph as NGBP-PJT. According to our simulation and experimental results, NGBP-PJT method outperforms NBP and NBP-TG in terms of accuracy, computational, and communication cost in reasonably sized networks.

Savic, Vladimir; Zazo, Santiago

2013-12-01

231

Angiopoietin 2 regulates the transformation and integrity of lymphatic endothelial cell junctions.  

PubMed

Primitive lymphatic vessels are remodeled into functionally specialized initial and collecting lymphatics during development. Lymphatic endothelial cell (LEC) junctions in initial lymphatics transform from a zipper-like to a button-like pattern during collecting vessel development, but what regulates this process is largely unknown. Angiopoietin 2 (Ang2) deficiency leads to abnormal lymphatic vessels. Here we found that an ANG2-blocking antibody inhibited embryonic lymphangiogenesis, whereas endothelium-specific ANG2 overexpression induced lymphatic hyperplasia. ANG2 inhibition blocked VE-cadherin phosphorylation at tyrosine residue 685 and the concomitant formation of button-like junctions in initial lymphatics. The defective junctions were associated with impaired lymph uptake. In collecting lymphatics, adherens junctions were disrupted, and the vessels leaked upon ANG2 blockade or gene deletion. ANG2 inhibition also suppressed the onset of lymphatic valve formation and subsequent valve maturation. These data identify ANG2 as the first essential regulator of the functionally important interendothelial cell-cell junctions that form during lymphatic development. PMID:25030698

Zheng, Wei; Nurmi, Harri; Appak, Sila; Sabine, Amélie; Bovay, Esther; Korhonen, Emilia A; Orsenigo, Fabrizio; Lohela, Marja; D'Amico, Gabriela; Holopainen, Tanja; Leow, Ching Ching; Dejana, Elisabetta; Petrova, Tatiana V; Augustin, Hellmut G; Alitalo, Kari

2014-07-15

232

Angiopoietin 2 regulates the transformation and integrity of lymphatic endothelial cell junctions  

PubMed Central

Primitive lymphatic vessels are remodeled into functionally specialized initial and collecting lymphatics during development. Lymphatic endothelial cell (LEC) junctions in initial lymphatics transform from a zipper-like to a button-like pattern during collecting vessel development, but what regulates this process is largely unknown. Angiopoietin 2 (Ang2) deficiency leads to abnormal lymphatic vessels. Here we found that an ANG2-blocking antibody inhibited embryonic lymphangiogenesis, whereas endothelium-specific ANG2 overexpression induced lymphatic hyperplasia. ANG2 inhibition blocked VE-cadherin phosphorylation at tyrosine residue 685 and the concomitant formation of button-like junctions in initial lymphatics. The defective junctions were associated with impaired lymph uptake. In collecting lymphatics, adherens junctions were disrupted, and the vessels leaked upon ANG2 blockade or gene deletion. ANG2 inhibition also suppressed the onset of lymphatic valve formation and subsequent valve maturation. These data identify ANG2 as the first essential regulator of the functionally important interendothelial cell–cell junctions that form during lymphatic development. PMID:25030698

Zheng, Wei; Nurmi, Harri; Appak, Sila; Sabine, Amélie; Bovay, Esther; Korhonen, Emilia A.; Orsenigo, Fabrizio; Lohela, Marja; D’Amico, Gabriela; Holopainen, Tanja; Leow, Ching Ching; Dejana, Elisabetta; Petrova, Tatiana V.; Augustin, Hellmut G.; Alitalo, Kari

2014-01-01

233

75 FR 6094 - Modification of Class E Airspace; Grand Junction, CO  

Federal Register 2010, 2011, 2012, 2013, 2014

...Modification of Class E Airspace; Grand Junction, CO AGENCY: Federal Aviation Administration...Grand Junction Regional, Grand Junction, CO, to accommodate the vectoring of Instrument...Grand Junction Regional, Grand Junction, CO to en route airspace, and changes the...

2010-02-08

234

Junction Field-Effect Transistors  

NSDL National Science Digital Library

All About Circuits is a website that â??provides a series of online textbooks covering electricity and electronics.â? Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Junction Field-Effect Transistors, is the fifth chapter in Volume III â?? Semiconductors. A few of the topics covered in this chapter include: Meter check of a transistor and Active-mode operation. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

235

LOW RESISTANCE JUNCTIONS IN CRAYFISH  

PubMed Central

Low resistance junctions between axons of crayfish ganglia are studied by freeze-fracture and negative staining. In freeze-fracture, fracture planes that go through a junctional membrane expose two faces, both internal, called face A and face B. Face A belongs to the internal membrane leaflet and faces the gap. Face B belongs to the external membrane leaflet and faces the axoplasm. Face A displays pits, 60–100 Å in diameter, arranged in a hexagonal array with a unit cell of ?200 Å. An ?25 Å bump is frequently seen at the center of each pit. Some pits are occupied by a globule ?125 Å in diameter, which displays a central depression ?25 Å in size. Face B contains globules also arranged in a fairly regular hexagonal pattern. The center-to-center distance between adjacent globules is most frequently ?200 Å; however, occasionally certain globules are seen separated by a distance as short as ?125 Å. The top surface of the globules occasionally displays a starlike profile and seems to contain a central depression ?25 Å in diameter. In negatively stained preparations of membranes from the nerve cord, two types of membranes are seen containing a fairly regular pattern. In one, globules ?95 Å in diameter form a hexagonal close packing with a unit cell of ?95 Å. In the other, globules of the same size are organized in a larger hexagonal array with a unit cell of ?155 Å (swollen arrangement). Some of the globules forming the swollen arrangement are seen containing six subunits. The six subunits form a hexagon which is skewed with respect to the main rows of hexagons in such a way that the subunits lie on rows which make an angle of ?37° with the main rows. PMID:4120611

Peracchia, Camillo

1973-01-01

236

Electric field breakdown in single molecule junctions.  

PubMed

Here we study the stability and rupture of molecular junctions under high voltage bias at the single molecule/single bond level using the scanning tunneling microscope-based break-junction technique. We synthesize carbon-, silicon-, and germanium-based molecular wires terminated by aurophilic linker groups and study how the molecular backbone and linker group affect the probability of voltage-induced junction rupture. First, we find that junctions formed with covalent S-Au bonds are robust under high voltage and their rupture does not demonstrate bias dependence within our bias range. In contrast, junctions formed through donor-acceptor bonds rupture more frequently, and their rupture probability demonstrates a strong bias dependence. Moreover, we find that the junction rupture probability increases significantly above ?1 V in junctions formed from methylthiol-terminated disilanes and digermanes, indicating a voltage-induced rupture of individual Si-Si and Ge-Ge bonds. Finally, we compare the rupture probabilities of the thiol-terminated silane derivatives containing Si-Si, Si-C, and Si-O bonds and find that Si-C backbones have higher probabilities of sustaining the highest voltage. These results establish a new method for studying electric field breakdown phenomena at the single molecule level. PMID:25675085

Li, Haixing; Su, Timothy A; Zhang, Vivian; Steigerwald, Michael L; Nuckolls, Colin; Venkataraman, Latha

2015-04-22

237

Transport properties of Andreev polarons in a superconductor-semiconductor-superconductor junction with superlattice structure  

NASA Astrophysics Data System (ADS)

In superconductor-semiconductor-superconductor (Su-Sm-Su) junctions with superlattice structure, differential resistance as a function of voltage shows oscillatory behavior under the irradiation of radio-frequency (rf) waves with specific frequency regardless of the superconducting materials and the junction geometries. We interpret quantitatively this newly discovered phenomenon in terms of the coupling of superconducting quasiparticles with long-wavelength acoustic phonons indirectly excited by the rf waves. We propose that the strong coupling causes the formation of novel composite particles which we named Andreev polarons.

Inoue, Ryotaro; Takayanagi, Hideaki

2012-09-01

238

Transport properties of Andreev polarons in a superconductor-semiconductor-superconductor junction with superlattice structure.  

PubMed

Transport properties of a superconductor-semiconductor-superconductor (Su-Sm-Su) junction with superlattice structure are investigated. Differential resistance as a function of voltage shows oscillatory behavior under the irradiation of radio-frequency (rf) waves with the specific frequency of 1.77 GHz regardless of the superconducting materials and the junction geometries. Experimental data are quantitatively explained in terms of the coupling of superconducting quasiparticles with long-wavelength acoustic phonons indirectly excited by the rf waves. We propose that the strong coupling causes the formation of novel composite particles, Andreev polarons. PMID:21568603

Inoue, Ryotaro; Muranaga, Kenta; Takayanagi, Hideaki; Hanamura, Eiichi; Jo, Masafumi; Akazaki, Tatsushi; Suemune, Ikuo

2011-04-15

239

Carbon nanotube based magnetic tunnel junctions  

PubMed

Spin-coherent quantum transport in carbon nanotube magnetic tunnel junctions is investigated theoretically. A spin-valve effect is found for metallic, armchair tubes, with a magnetoconductance ratio ranging up to 20%. Because of the finite length of the nanotube junctions, transport is dominated by resonant transmission. The magnetic tunnel junctions are found to have distinctly different transport behavior depending on whether or not the length of the tubes is commensurate with a 3N+1 rule, with N the number of basic carbon repeat units along the nanotube length. PMID:11017299

Mehrez; Taylor; Guo; Wang; Roland

2000-03-20

240

Microwave photon counter based on Josephson junctions.  

PubMed

We describe a microwave photon counter based on the current-biased Josephson junction. The junction is tuned to absorb single microwave photons from the incident field, after which it tunnels into a classically observable voltage state. Using two such detectors, we have performed a microwave version of the Hanbury Brown-Twiss experiment at 4 GHz and demonstrated a clear signature of photon bunching for a thermal source. The design is readily scalable to tens of parallelized junctions, a configuration that would allow number-resolved counting of microwave photons. PMID:22181922

Chen, Y-F; Hover, D; Sendelbach, S; Maurer, L; Merkel, S T; Pritchett, E J; Wilhelm, F K; McDermott, R

2011-11-18

241

The myoendothelial junction: breaking through the matrix?  

PubMed Central

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; Straub, Adam; Isakson, Brant E

2009-01-01

242

Graded junction termination extensions for electronic devices  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

243

Graded junction termination extensions for electronic devices  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

244

Acoustic hybrid junction in a rectangular waveguide  

PubMed

Acoustic scattering from a hybrid junction in a rectangular waveguide is studied. The Fourier transform and mode matching is used to represent the scattered wave and the simultaneous equations for the modal coefficients are formulated. A residue calculus is utilized to obtain a solution to the simultaneous equations in fast-converging series. Numerical computations are performed to show the behavior of transmission in terms of junction geometry and operating frequency. The utility of acoustic hybrid junction is discussed in terms of its decoupling characteristics. PMID:10790010

Kwon; Eom

2000-04-01

245

Silicon fiber with p-n junction  

NASA Astrophysics Data System (ADS)

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

Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B.

2014-09-01

246

Modeling Social Network Relationships via t-Cherry Junction Trees  

E-print Network

Modeling Social Network Relationships via t-Cherry Junction Trees Brian Proulx and Junshan Zhang the underlying structure therein. In this paper, we employ the t-cherry junction tree, a very recent advancement in this approach: 1) the best approximation possible via junction trees belongs to the class of t-cherry junction

Reisslein, Martin

247

Tunnel junction multiple wavelength light-emitting diodes  

DOEpatents

A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect.

Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO)

1992-01-01

248

Tunnel junction multiple wavelength light-emitting diodes  

DOEpatents

A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect. 5 figs.

Olson, J.M.; Kurtz, S.R.

1992-11-24

249

The loss of boron in ultra-shallow boron implanted Si under heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Heavy ion impact has been known to cause a loss of light elements from the near-surface region of the irradiated sample. One of the possible approaches to a better understanding of the processes responsible for the release of specific elements is to irradiate shallow-implanted samples, which exhibit a well-known depth distribution of the implanted species. In this work, the samples studied were produced by implantation of Si wafers with 11 B at implantation energies of 250 and 500 eV and fluence of 1.0x10(15) atoms/cm 2 . Elastic Recoil Detection Analysis was applied to monitor the remnant boron fluence in the sample. Irradiation of the samples by a 14.2 (MeVF4+)-F-19 beam resulted in a slow decrease of boron remnant fluence with initial loss rates of the order of 0.05 B atom per impact ion. Under irradiation with 12 (MeVS3+)-S-32 ions, the remnant boron fluence in Si decreased exponentially with a much faster loss rate of boron and became constant after a certain heavy ion irradiation dose. A simple model, which assumes a finite desorption range and corresponding depletion of the near-surface region, was used to describe the observations. The depletion depths under the given irradiation conditions were calculated from the measured data.

Pelicon, P.; El Bouanani, M.; Prasad, G. V. R.; Razpet, A.; Simcic, J.; Guo, B. N.; Birt, D.; Duggan, J. L.; McDaniel, F. D.

2006-08-01

250

Plasma Implantation Technology for Upcoming Ultra Shallow and Highly Doped Fully Depleted Silicon On Insulator Transistors  

NASA Astrophysics Data System (ADS)

To face the continuous dimensions downscaling for upcoming semiconductor devices, we have investigated a plasma immersion ion implantation way and have compared the results to a conventional one. This new implantation method allows, in particular, high and thin doping concentration to field source and drain requirements for 32 nm node and below. In addition to this key step, a silicon selective epitaxy growth has been performed. Thus, n-type and p-type ion implantations have been carried out on thin blanket SOI substrates in Pulsion® plasma ion implantation tool manufactured by Ion Beam Services, with AsH3, BF3 or B2H6 precursors. Then a recrystallization annealing followed by silicon selective epitaxial growth has been performed in a reduced pressure chemical vapor deposition tool. Regarding n-type implantation we observed a poly-silicon growth in areas where the top silicon has been amorphous down to the buried oxide and a mono-silicon growth for areas where the top silicon has not been completely amorphous. Indeed, in this case recrystallization annealing was not sufficient to allow lengthwise solid phase epitaxy growth whereas there were no difficulties for axial one. Regarding p-type implantations no epitaxial growths have been observed at all. This lack of growth cannot be explained by a complete silicon amorphization which would have led to a growth of poly-silicon like for n-type implantation. According to our first results this growth vacancy could be explained by the very high boron atoms concentration on the substrate surface. The latter being resistant to HF-last cleaning could thus block silicon nucleation. However some rinsing processes, more or less aggressive, have been tested to remove this boron silicon alloy layer. Among these different tests, hydrochloric or plasma etching have provided, in some specific cases, promising results allowing an epitaxial silicon growth.

Gonzatti, Frederic; Milési, Frederic; Delaye, Vincent; Duchaine, Julian; Torregrosa, Frank; Etienne, Hasnaa; Yckache, Karim

2011-01-01

251

Method of junction formation for CIGS photovoltaic devices  

DOEpatents

Sulfur is used to improve the performance of CIGS devices prepared by the evaporation of a single source ZIS type compound to form a buffer layer on the CIGS. The sulfur may be evaporated, or contained in the ZIS type material, or both. Vacuum evaporation apparatus of many types useful in the practice of the invention are known in the art. Other methods of delivery, such as sputtering, or application of a thiourea solution, may be substituted for evaporation.

Delahoy, Alan E. (Rocky Hill, NJ)

2010-01-26

252

Method of junction formation for CIGS photovoltaic devices  

DOEpatents

Sulfur is used to improve the performance of CIGS devices prepared by the evaporation of a single source ZIS type compound to form a buffer layer on the CIGS. The sulfur may be evaporated, or contained in the ZIS type material, or both. Vacuum evaporation apparatus of many types useful in the practice of the invention are known in the art. Other methods of delivery, such as sputtering, or application of a thiourea solution, may be substituted for evaporation.

Delahoy, Alan E.

2006-03-28

253

Increasing Gap Junctional Coupling: A Tool for Dissecting the Role of Gap Junctions  

Microsoft Academic Search

Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments\\u000a where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions\\u000a are important in many physiological processes. In a number of cases, gap junctions have been implicated in the initiation\\u000a and progress of disease,

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

2007-01-01

254

Chirality effect in disordered graphene ribbon junctions  

NASA Astrophysics Data System (ADS)

We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon.

Long, Wen

2012-05-01

255

MOBILITY IN GRAND JUNCTION DAVID SCHRANK  

E-print Network

INSTITUTE TIM LOMAX RESEARCH ENGINEER TEXAS TRANSPORTATION INSTITUTE TIM BAKER UNIT MANAGER, MOBILITY White · Joe Hill City of Grand Junction Transportation Department · Jody Kliska · Sandra Mallory

256

Development of nano and micro SQUIDs based on Al tunnel junctions  

NASA Astrophysics Data System (ADS)

Superconducting quantum interference devices (SQUIDs) with nano (micro)-meter dimensions are called nano (micro)-SQUIDs. The high sensitivity for flux and position of nano (micro)-SQUIDs can be applied to detect local magnetic fields induced by vortices and the magnetization of mesoscopic superconductors. Nano-SQUIDs based on carbon-nanotube junctions and niobium weak junctions are well known. However, such nano-SQUIDs are not suitable for large-scale integrated circuits and mass production. Therefore, we employ a combination of lithography using the Niemeyer-Dolan technique and the inductively coupled plasma reactive-ion etching technique to fabricate nano-SQUIDs. Here, we report the fabrication of nano (micro)-SQUIDs based on superconducting aluminum tunnel junctions and their application for vortex formation into mesoscopic chiral superconducting Sr2RuO4[1-3].

Ishiguro, Ryosuke; Watanabe, Eiichiro; Sakuma, Daisuke; Shinozaki, Tomoya; Tsuchiya, Shogo; Nago, Yusuke; Osato, Hirotaka; Tsuya, Daiju; Kashiwaya, Hiromi; Kashiwaya, Satoshi; Nomura, Shintaro; Takayanagi, Hideaki; Maeno, Yoshiteru

2014-12-01

257

Charge transport and Kelvin Probe study of organic semiconductor hetero-junction  

NASA Astrophysics Data System (ADS)

We have synthesized organic hetero-junction comprising of n-type copper hexadecafluorophthalocyanine (F16CuPc) / p-type cobalt phthalocyanine (CoPc) using molecular beam epitaxy (MBE). The current - voltage (J-V) characteristics of hetero-junction are ohmic in the entire bias range (0-100 V), while individual films shows a transition from ohmic to space charge limited conduction with increasing bias. Hetero-junction shows one order of magnitude higher current density than individual F16CuPc and CoPc films, indicating the formation of a charge accumulation layers at the interface. The thickness of charge accumulation regions was found to be ˜ 16 nm using Kelvin Probe (KP) method.

Kumar, Arvind; Samanta, Soumen; Singh, Ajay; Debnath, A. K.; Prasad, R.; Aswal, D. K.; Gupta, S. K.

2012-06-01

258

Large-Signal Behavior of Junction Transistors  

Microsoft Academic Search

In the consideration of the junction transistor as a switch there are three characteristics of primary interest, the open impedance, the closed impedance, and the switching-time. A generalized two-terminal-pair theory of junction transistors is presented which is applicable, on a dc basis, in all regions of operation. Using this theory, the open and closed impedances of the transistor switch are

J. J. Ebers; J. L. Moll

1954-01-01

259

Rho Signaling and Tight Junction Functions  

NSDL National Science Digital Library

Tight junctions are heteromeric protein complexes that act as signaling centers by mediating the bidirectional transmission of information between the environment and the cell interior to control paracellular permeability and differentiation. Insight into tight junction-associated signaling mechanisms is of fundamental importance for our understanding of the physiology of epithelia and endothelia in health and disease. Review of RhoGTPase effector pathways and paracellular permeability

Steve Terry (University College London)

2010-02-01

260

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

261

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. 5 figs.

Klem, J.F.; Zolper, J.C.

1997-10-21

262

Capacitance extraction in arbitrarily diffused junction  

E-print Network

B. Objective C. Outline. II IMPURITY PROFILE OF A BIPOLAR TRANSISTOR A. Impurity distribution of the diffused semiconductor B. One-dimensional impurity profile of the test structure III A GENERAL METHOD FOR CALCULATING THE RE- VERSE BIASED P... transistor Many junctions which exist in the vertical npn bipolar transistor . 10 Functional form one-dimensional impurity profile of the test structure 12 A general one-dimensional model for a vertical npn transistor Diffused emitter-base junction of a...

Chung, Tae-Song

1990-01-01

263

A metal-insulator-silicon junction seal  

Microsoft Academic Search

Most semiconductor devices today have a costly vacuum-tight encapsulation that provides a microenvironment for high reliability and electrical connections to the circuit in which it is used. A junction seal consisting of a metal-insulator-silicon (MIS) system of materials has been developed to replace the vacuum-tight encapsulation. The MIS junction seal, consisting of platinum silicide-titanium-platinum-gold contacts and a Silicon nitride overcoat,

G. H. Schneer; W. van Gelder; V. E. Hauser; P. F. Schmidt

1968-01-01

264

Epidermal tight junctions in health and disease.  

PubMed

The skin, the largest organ of the body, is an essential barrier that under homeostatic conditions efficiently protects and/or minimizes damage from both environmental (e.g. microorganisms, physical trauma, ultraviolet radiation) and endogenous (e.g., cancers, inflammation) factors. This formidable barrier function resides mainly in the epidermis, a dynamic, highly-stratified epithelium. The epidermis has 2 major barrier structures: stratum corneum, the outmost layer and tight junctions, intercellular junctions that seal adjacent keratinocytes in the stratum granulosum, found below the stratum corneum. In recent years there have been significant advances in our understanding of tight junction function, composition and regulation. Herein we review what is known about tight junctions in healthy skin and keratinocyte culture systems and highlight the dynamic crosstalk observed between tight junctions and the cutaneous immune system. Finally we discuss the preliminary observations suggesting that tight junction function or protein expression may be relevant for the pathogenesis of a number of common cutaneous inflammatory and neoplastic conditions. PMID:25838981

Brandner, J M; Zorn-Kruppa, M; Yoshida, T; Moll, I; Beck, L A; De Benedetto, A

2015-01-01

265

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

266

Visualization of cellular mechanisms regulating differential neuronal synapse formation  

E-print Network

the idea that gap junctional coupling synchronizes the synaptogenic establishment of functional neural networks. Helisoma neuronal pairs treated with trophic factors exhibit increased electrical coupling and subsequently delay the formation of inhibitory...

Neunuebel, Joshua Paul

2005-11-01

267

Correlation between micromagnetism and tunnel magnetoresistance in magnetic tunnel junctions using artificial ferrimagnets  

NASA Astrophysics Data System (ADS)

The impact of the micromagnetic configuration on transport properties of magnetic tunnel junctions is presented. An artificial ferrimagnet system (AFi), made of two ferromagnetic layers with different magnetic moments antiferromagnetically coupled by exchange interactions through a Ru spacer layer, is used as a hard magnetic subsystem of the magnetic junction. Magnetic-force microscopy studies have shown that the magnetization reversal in artificial ferrimagnet systems occurs through the formation of Néel-type 360° domain walls. The stability of these walls is demonstrated to be different in the two magnetic layers of the AFi. These aspects have major effects in magnetic tunnel junction devices, due to the extreme sensitivity of spin tunneling to spatial variations in local magnetic order. The large tunnel magnetoresistance (TMR) of our samples, in the range of 20-30 % at room temperature, makes the tunnel junctions highly sensitive to magnetic fluctuations. A sharp switching of the soft magnetic layer upon field reversal prevents a domain structure from occurring in the soft magnetic layer, in the field window used for our micromagnetic studies. The tunnel device can thus be used as a sensitive probe for measuring small magnetic fluctuations associated with micromagnetic defects, domains, and walls in the AFi system. These fluctuations modulate the resistance of the tunnel junction and are fully reflected in the shape and the amplitude of the TMR signal.

Tiusan, C.; Dimopoulos, T.; Ounadjela, K.; Hehn, M.; van den Berg, H. A. M.; da Costa, V.; Henry, Y.

2000-01-01

268

Correlation of interfacial bonding mechanism and equilibrium conductance of molecular junctions  

NASA Astrophysics Data System (ADS)

We report theoretical investigations on the role of interfacial bonding mechanism and its resulting structures to quantum transport in molecular wires. Two bonding mechanisms for the Au-S bond in an Au(111)/1,4-benzenedithiol(BDT)/Au(111) junction were identified by ab initio calculation, confirmed by a recent experiment, which, we showed, critically control charge conduction. It was found, for Au/BDT/Aujunctions, the hydrogen atom, bound by a dative bond to the Sulfur, is energetically non-dissociativeafter the interface formation. The calculated conductance and junction breakdown forces of H-non-dissociative Au/BDT/Au devices are consistent with the experimental values, while the H-dissociated devices, with the interface governed by typical covalent bonding, give conductance more than an order of magnitude larger. By examining the scattering states that traverse the junctions, we have revealed that mechanical and electric properties of a junction have strong correlation with the bonding configuration. This work clearly demonstrates that the interfacial details, rather than previously believed many-body effects, is of vital importance for correctly predicting equilibrium conductance of molecular junctions; and manifests that the interfacial contact must be carefully understood for investigating quantum transport properties of molecular nanoelectronics.

Ning, Zhan-Yu; Qiao, Jing-Si; Ji, Wei; Guo, Hong

2014-12-01

269

Black Diamonds at Brane Junctions  

E-print Network

We discuss the properties of black holes in brane-world scenarios where our universe is viewed as a four-dimensional sub-manifold of some higher-dimensional spacetime. We consider in detail such a model where four-dimensional spacetime lies at the junction of several domain walls in a higher dimensional anti-de Sitter spacetime. In this model there may be any number p of infinitely large extra dimensions transverse to the brane-world. We present an exact solution describing a black p-brane which will induce on the brane-world the Schwarzschild solution. This exact solution is unstable to the Gregory-Laflamme instability, whereby long-wavelength perturbations cause the extended horizon to fragment. We therefore argue that at late times a non-rotating uncharged black hole in the brane-world is described by a deformed event horizon in p+4 dimensions which will induce, to good approximation, the Schwarzschild solution in the four-dimensional brane world. When p=2, this deformed horizon resembles a black diamond and more generally for p>2, a polyhedron.

Andrew Chamblin; Csaba Csaki; Joshua Erlich; Timothy J. Hollowood

2000-02-10

270

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

271

The junction size effect on the electromigration flow of copper atoms through carbon-nanotube junctions  

Microsoft Academic Search

The size effect of carbon nanotube (CNT) channel junctions on the flow of copper atoms is investigated using molecular dynamics simulations. A bias voltage is applied along the channel to induce an electromigration force to drive the copper atoms. The study has revealed that the size of the junctions affects the configuration of copper atoms, which is reflected as a

M. C. G. Lim; Z. W. Zhong

2011-01-01

272

Clathrin and Cx43 gap junction plaque endoexocytosis  

SciTech Connect

In earlier transmission electron microscopic studies, we have described pentilaminar gap junctional membrane invaginations and annular gap junction vesicles coated with short, electron-dense bristles. The similarity between these electron-dense bristles and the material surrounding clathrin-coated pits led us to suggest that the dense bristles associated with gap junction structures might be clathrin. To confirm that clathrin is indeed associated with annular gap junction vesicles and gap junction plaques, quantum dot immuno-electron microscopic techniques were used. We report here that clathrin associates with both connexin 43 (Cx43) gap junction plaques and pentilaminar gap junction vesicles. An important finding was the preferential localization of clathrin to the cytoplasmic surface of the annular or of the gap junction plaque membrane of one of the two contacting cells. This is consistent with the possibility that the direction of gap junction plaque internalization into one of two contacting cells is regulated by clathrin.

Nickel, Beth M.; DeFranco, B. Hewa; Gay, Vernon L. [Department of Cell Biology and Physiology, University of Pittsburgh, School of Medicine, 324 South Biomedical Science Tower, Pittsburgh, PA 15261 (United States); Murray, Sandra A. [Department of Cell Biology and Physiology, University of Pittsburgh, School of Medicine, 324 South Biomedical Science Tower, Pittsburgh, PA 15261 (United States)], E-mail: smurray@pitt.edu

2008-10-03

273

Clathrin and Cx43 gap junction plaque endoexocytosis.  

PubMed

In earlier transmission electron microscopic studies, we have described pentilaminar gap junctional membrane invaginations and annular gap junction vesicles coated with short, electron-dense bristles. The similarity between these electron-dense bristles and the material surrounding clathrin-coated pits led us to suggest that the dense bristles associated with gap junction structures might be clathrin. To confirm that clathrin is indeed associated with annular gap junction vesicles and gap junction plaques, quantum dot immuno-electron microscopic techniques were used. We report here that clathrin associates with both connexin 43 (Cx43) gap junction plaques and pentilaminar gap junction vesicles. An important finding was the preferential localization of clathrin to the cytoplasmic surface of the annular or of the gap junction plaque membrane of one of the two contacting cells. This is consistent with the possibility that the direction of gap junction plaque internalization into one of two contacting cells is regulated by clathrin. PMID:18675253

Nickel, Beth M; DeFranco, B Hewa; Gay, Vernon L; Murray, Sandra A

2008-10-01

274

Role of tight junction proteins in gastroesophageal reflux disease  

PubMed Central

Background Gastroesophageal reflux disease (GERD) is associated with impaired epithelial barrier function that is regulated by cell-cell contacts. The aim of the study was to investigate the expression pattern of selected components involved in the formation of tight junctions in relation to GERD. Methods Eighty-four patients with GERD-related symptoms with endoscopic signs (erosive: n?=?47) or without them (non-erosive: n?=?37) as well as 26 patients lacking GERD-specific symptoms as controls were included. Endoscopic and histological characterization of esophagitis was performed according to the Los Angeles and adapted Ismeil-Beigi criteria, respectively. Mucosal biopsies from distal esophagus were taken for analysis by histopathology, immunohistochemistry and quantitative reverse-transcription polymerase chain reaction (RT-PCR) of five genes encoding tight junction components [Occludin, Claudin-1, -2, Zona occludens (ZO-1, -2)]. Results Histopathology confirmed GERD-specific alterations as dilated intercellular spaces in the esophageal mucosa of patients with GERD compared to controls (P?junction-related components and histomorphological GERD-specific alterations does not support a major role of the five proteins studied in the pathogenesis of GERD. PMID:22994974

2012-01-01

275

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

276

Lateral assembly of N-cadherin drives tissue integrity by stabilizing adherens junctions.  

PubMed

Cadherin interactions ensure the correct registry and anchorage of cells during tissue formation. Along the plasma membrane, cadherins form inter-junctional lattices via cis- and trans-dimerization. While structural studies have provided models for cadherin interactions, the molecular nature of cadherin binding in vivo remains unexplored. We undertook a multi-disciplinary approach combining live cell imaging of three-dimensional cell assemblies (spheroids) with a computational model to study the dynamics of N-cadherin interactions. Using a loss-of-function strategy, we demonstrate that each N-cadherin interface plays a distinct role in spheroid formation. We found that cis-dimerization is not a prerequisite for trans-interactions, but rather modulates trans-interfaces to ensure tissue stability. Using a model of N-cadherin junction dynamics, we show that the absence of cis-interactions results in low junction stability and loss of tissue integrity. By quantifying the binding and unbinding dynamics of the N-cadherin binding interfaces, we determined that mutating either interface results in a 10-fold increase in the dissociation constant. These findings provide new quantitative information on the steps driving cadherin intercellular adhesion and demonstrate the role of cis-interactions in junction stability. PMID:25589573

Garg, S; Fischer, S C; Schuman, E M; Stelzer, E H K

2015-03-01

277

A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment.  

PubMed

Craniospinal irradiation (CSI) requires abutting fields at the cervical spine. Junction shifts are conventionally used to prevent setup error-induced overdosage/underdosage from occurring at the same location. This study compared the dosimetric differences at the cranial-spinal junction between a single-gradient junction technique and conventional multiple-junction shifts and evaluated the effect of setup errors on the dose distributions between both techniques for a treatment course and single fraction. Conventionally, 2 lateral brain fields and a posterior spine field(s) are used for CSI with weekly 1-cm junction shifts. We retrospectively replanned 4 CSI patients using a single-gradient junction between the lateral brain fields and the posterior spine field. The fields were extended to allow a minimum 3-cm field overlap. The dose gradient at the junction was achieved using dose painting and intensity-modulated radiation therapy planning. The effect of positioning setup errors on the dose distributions for both techniques was simulated by applying shifts of ± 3 and 5mm. The resulting cervical spine doses across the field junction for both techniques were calculated and compared. Dose profiles were obtained for both a single fraction and entire treatment course to include the effects of the conventional weekly junction shifts. Compared with the conventional technique, the gradient-dose technique resulted in higher dose uniformity and conformity to the target volumes, lower organ at risk (OAR) mean and maximum doses, and diminished hot spots from systematic positioning errors over the course of treatment. Single-fraction hot and cold spots were improved for the gradient-dose technique. The single-gradient junction technique provides improved conformity, dose uniformity, diminished hot spots, lower OAR mean and maximum dose, and one plan for the entire treatment course, which reduces the potential human error associated with conventional 4-shifted plans. PMID:24913466

Hadley, Austin; Ding, George X

2014-01-01

278

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

279

Josephson junctions with nearly superconducting metal silicide barriers  

NASA Astrophysics Data System (ADS)

We present a detailed study of the electrical properties of Nb-based planar Josephson junctions with superconducting metal silicide barriers, TiSi2 and WSi2. While these nonhysteretic junctions are useful for voltage standard applications, they are also an excellent model system to study proximity coupling in junctions having a barrier with a finite superconducting transition temperature. These silicide-barrier junctions have excellent uniformity and controllability, but as opposed to junction barriers with no measurable superconducting transition, the critical current of these superconducting-barrier junctions is a strong function of the operating temperature near 4 K; we also discuss the impact of this temperature dependence on device applications.

Chong, Yonuk; Hadacek, N.; Dresselhaus, P. D.; Burroughs, C. J.; Baek, B.; Benz, S. P.

2005-11-01

280

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

281

Nonlinear pattern dynamics in Josephson-junction arrays  

NASA Astrophysics Data System (ADS)

The dynamics of a two-dimensional array of Josephson junctions under an external load is shown to be equivalent to that of a one-dimensional nonlinear chain of nonidentical, globally, and nonuniformly coupled oscillators. This allows us to determine the dynamical states and collective spatiotemporal patterns the array exhibits in response to varying initial conditions, input patterns, coupling strengths, and bias current. When the bias current goes through critical values, successive bifurcations activate spatially distinct, coupled oscillatory compartments in the array, where semirotating, whirling, and quasiperiodic and aperiodic states coexist, and induce staircase current-voltage characteristics. Classical and vortex-induced row switching phenomena, stable families of frequency synchronized and phase-locked states, subharmonics in compartment couplings, stochastic jumps, and hysteresis loops are deduced, and sequences of input patterns are shown to be dynamically storable in the array's attractors. The dynamical formation of oscillatory compartments is also a general feature of three-dimensional Josephson-junction networks. Coherent microwave radiation emission is possible only for specific input patterns or by using symmetry-breaking array architectures. The theoretical predictions are in close agreement with the dynamics recently observed in low-temperature scanning electron microscopy experiments.

Oppenländer, J.; Dangelmayr, G.; Güttinger, W.

1996-07-01

282

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

283

Exploring Hot Gas at Junctions of Galaxy Filaments with Suzaku  

NASA Astrophysics Data System (ADS)

Galaxies are forced to form filamentary structure reflecting the underlying cosmic web of the dark matter. In particular, at junctions of galaxy filaments, one can naturally expect that intense structure formation has high chances to occur. We identified the galaxy filaments by making use of our original method (Sousbie (2011) & Sousbie et al. (2011)) in conjunction with SDSS spectroscopic galaxies. We performed X-ray pointing observations for 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 compared to a background region. Spectral analysis revealed that six sources originate from diffuse emissions associated with optically bright galaxies, group-scale, or cluster-scale X-ray halos with temperautres of 1-4 keV, while the others are compact object origin. Interestingly, the observed three intracluster media possess peculiar signatures such as complex or elongated morphologies in X-ray and/or optical and hot spot, suggesting that all of the systems are experiencing an ongoing merger (Kawahara et al. (2011) & Mitsuishi et al. (2014)). In this conference, results of follow-up radio observations to search for merger-induced diffuse radio emissions will be reported.

Mitsuishi, I.; Kawahara, H.; Sekiya, N.; Sasaki, S.; Sousbie, T.; Y. Yamasaki, N.

2014-07-01

284

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

285

Electrostatic Modeling of Vacuum Insulator Triple Junctions  

SciTech Connect

Triple junctions are often initiation points for insulator flashover in pulsed power devices. The two-dimensional finite-element TriComp [1] modeling software suite was utilized for its electrostatic field modeling package to investigate electric field behavior in the anode and cathode triple junctions of a high voltage vacuum-insulator interface. TriComp enables simple extraction of values from a macroscopic solution for use as boundary conditions in a subset solution. Electric fields computed with this zoom capability correlate with theoretical analysis of the anode and cathode triple junctions within submicron distances for nominal electrode spacing of 1.0 cm. This paper will discuss the iterative zoom process with TriComp finite-element software and the corresponding theoretical verification of the results.

Tully, L K; Goerz, D A; Houck, T L; Javedani, J B

2006-10-25

286

Junction-side illuminated silicon detector arrays  

DOEpatents

A junction-side illuminated detector array of pixelated detectors is constructed on a silicon wafer. A junction contact on the front-side may cover the whole detector array, and may be used as an entrance window for light, x-ray, gamma ray and/or other particles. The back-side has an array of individual ohmic contact pixels. Each of the ohmic contact pixels on the back-side may be surrounded by a grid or a ring of junction separation implants. Effective pixel size may be changed by separately biasing different sections of the grid. A scintillator may be coupled directly to the entrance window while readout electronics may be coupled directly to the ohmic contact pixels. The detector array may be used as a radiation hardened detector for high-energy physics research or as avalanche imaging arrays.

Iwanczyk, Jan S.; Patt, Bradley E.; Tull, Carolyn

2004-03-30

287

Effect of disorder on longitudinal resistance of a graphene p-n junction in the quantum Hall regime  

NASA Astrophysics Data System (ADS)

The longitudinal resistances of a six-terminal graphene p-n junction under a perpendicular magnetic field are investigated. Because of the chirality of the Hall edge states, the longitudinal resistances on top and bottom edges of the graphene ribbon are not equal. In the presence of suitable disorder, the top-edge and bottom-edge resistances well show the plateau structures in the both unipolar and bipolar regimes, and the plateau values are determined by the Landau filling factors only. These plateau structures are in excellent agreement with the recent experiment. For the unipolar junction, the resistance plateaus emerge in the absence of impurity and they are destroyed by strong disorder. But for the bipolar junction, the resistances are very large without the plateau structures in the clean junction. The disorder can strongly reduce the resistances and leads the formation of the resistance plateaus due to the mixture of the Hall edge states in virtue of the disorder. In addition, the size effect of the junction on the resistances is studied and some extra resistance plateaus are found in the long graphene junction case. This is explained by the fact that only part of the edge states participate in the full mixing.

Chen, Jiang-Chai; Yeung, T. C. Au; Sun, Qing-Feng

2010-06-01

288

Organic/inorganic hybrid pn-junction between copper phthalocyanine and CdSe quantum dot layers as solar cells  

NASA Astrophysics Data System (ADS)

We have introduced an organic/inorganic hybrid pn-junction for solar cell applications. Layers of II-VI quantum dots and a metal-phthalocyanine in sequence have been used as n- and p-type materials, respectively, to form a junction. The film of quantum dots has been formed through a layer-by-layer process by replacing the long-chain ligands of the nanoparticles in each ultrathin layer or a monolayer with short-chain ones so that interparticle distance becomes small leading to a decrease in resistance of the quantum dot layer. With indium tin oxide and Au as electrodes, we have formed an inverted sandwiched structure. These electrodes formed ohmic contacts with the neighboring materials. From the current-voltage characteristics of the hybrid heterostructure, we have inferred formation of a depletion region at the pn-junction that played a key role in charge separation and correspondingly a photocurrent in the external circuit. For comparison, we have also formed and characterized Schottky devices based on components of the pn-junction keeping the electrode combination same. From capacitance-voltage characteristics, we have observed that the depletion region of the hybrid pn-junction was much wider as compared to that in Schottky devices based on components of the junction.

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

2012-08-01

289

Irsogladine maleate regulates gap junctional intercellular communication-dependent epithelial barrier in human nasal epithelial cells.  

PubMed

The airway epithelium of the human nasal mucosa acts as the first physical barrier that protects against inhaled substances and pathogens. Irsogladine maleate (IM) is an enhancer of gastric mucosal protective factors via upregulation of gap junctional intercellular communication (GJIC). GJIC is thought to participate in the formation of functional tight junctions. However, the effects of IM on GJIC and the epithelial barrier in human nasal epithelial cells (HNECs) remain unknown. To investigate the effects of IM on GJIC and the tight junctional barrier in HNECs, primary cultures of HNECs transfected with human telomerase reverse transcriptase (hTERT-HNECs) were treated with IM and the GJIC inhibitors oleamide and 18?-GA. Some cells were pretreated with IM before treatment with TLR3 ligand poly(I:C) to examine whether IM prevented the changes via TLR3-mediated signal pathways. In hTERT-HNECs, GJIC blockers reduced the expression of tight junction molecules claudin-1, -4, -7, occludin, tricellulin, and JAM-A. IM induced GJIC activity and enhanced the expression of claudin-1, -4, and JAM-A at the protein and mRNA levels with an increase of barrier function. GJIC blockers prevented the increase of the tight junction proteins induced by IM. Furthermore, IM prevented the reduction of JAM-A but not induction of IL-8 and TNF-? induced by poly(I:C). In conclusion, IM can maintain the GJIC-dependent tight junctional barrier via regulation of GJIC in upper airway nasal epithelium. Therefore, it is possible that IM may be useful as a nasal spray to prevent the disruption of the epithelial barrier by viral infections and exposure to allergens in human nasal mucosa. PMID:25652184

Miyata, Ryo; Nomura, Kazuaki; Kakuki, Takuya; Takano, Ken-Ichi; Kohno, Takayuki; Konno, Takumi; Sawada, Norimasa; Himi, Tetsuo; Kojima, Takashi

2015-04-01

290

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

291

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

292

Arrays of high temperature superconductor Josephson junctions  

NASA Astrophysics Data System (ADS)

The authors present results on parallel, series, and 2D arrays of high-temperature superconductor junctions. The parallel arrays show the expected field dependence of critical current and can function as vortex flow transistors. The series arrays give data about the spread in junction critical currents for the present process. The 2D arrays show many of the phenomena previously observed in low-Tc technology, such as field frustration of the phase transition, some evidence for superlattice states, and the tentative indications of giant Shapiro steps, showing large-scale cooperative behavior in the device.

Satchell, J. S.; Humphreys, R. G.; Edwards, J. A.; Chew, N. G.

1993-03-01

293

Complementary junction heterostructure field-effect transistor  

DOEpatents

A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits. 10 figs.

Baca, A.G.; Drummond, T.J.; Robertson, P.J.; Zipperian, T.E.

1995-12-26

294

Complementary junction heterostructure field-effect transistor  

DOEpatents

A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits.

Baca, Albert G. (Albuquerque, NM); Drummond, Timothy J. (Albuquerque, NM); Robertson, Perry J. (Albuquerque, NM); Zipperian, Thomas E. (Albuquerque, NM)

1995-01-01

295

Josephson junctions with alternating critical current density  

SciTech Connect

The magnetic-field dependence of the critical current I{sub c}(H) is considered for a short Josephson junction with the critical current density j{sub c} alternating along the tunnel contact. Two model cases, periodic and randomly alternating j{sub c}, are treated in detail. Recent experimental data on I{sub c}(H) for grain-boundary Josephson junctions in YBa{sub 2}Cu{sub 3}O{sub x} are discussed. {copyright} {ital 1997} {ital The American Physical Society}

Mints, R.G. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)] [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Kogan, V.G. [Ames Laboratory and Physics Department, Iowa State University, Ames, Iowa 50011 (United States)] [Ames Laboratory and Physics Department, Iowa State University, Ames, Iowa 50011 (United States)

1997-04-01

296

The multiple junction edge illuminated solar cell  

NASA Technical Reports Server (NTRS)

The multiple junction edge illuminated solar cell was devised for high voltage low current applications. Devices to be flight tested in early 1974 with 96 series connected PNN+ junctions in a 2 cm X 2.3 cm size deliver 36 volts at 1 milliampere. Test data of M-J cells fabricated with resistivities of 10, 50, 100, 200, 450, and 1000 ohm cm silicon are presented and problem areas are discussed. An additional potential application of the M-J cell lies in ultilization of its high intensity performance that has been demonstrated at levels in excess of 100 AMO suns.

Sater, B. I.; Brandhorst, H. W., Jr.; Riley, T. J.; Hart, R. E., Jr.

1973-01-01

297

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

298

Electrical characteristics and interface structure of magnetic tunnel junctions with hafnium oxyfluoride barrier  

SciTech Connect

We have studied the effects of fluorine inclusion on the electrical transport characteristics and interface structure of the hafnium oxide barrier in a magnetic tunnel junction. The tunneling magnetoresistance (TMR) and resistance-area (RA) as a function of oxidation time show that the TMR ratio of the hafnium oxyfluoride barrier is higher (8.3%) than that of the hafnium oxide barrier (5.7%) at their optimum conditions, and the oxyfluoride barrier junctions maintain a high TMR ratio even when the RA product increases by three orders of magnitude. X-ray photoelectron spectroscopy analysis shows that the fluorine atoms in the oxyfluoride barrier play an important role in the formation of a barrier with uniform composition. We believe that the initial fluoride layer is causing the subsequent oxygen diffusion to slow down, resulting in the formation of a defect-free hafnium oxide layer. These results are consistent with what we have found for aluminum oxyfluoride barriers.

Yu, Y.Y.; Kim, D.S.; Char, K. [Center for Strongly Correlated Materials Research and School of Physics, Seoul National University, Seoul 151-742 (Korea, Republic of)

2004-12-01

299

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

300

Ballistic bipolar junctions in chemically gated graphene ribbons.  

PubMed

The realization of ballistic graphene pn-junctions is an essential task in order to study Klein tunneling phenomena. Here we show that intercalation of Ge under the buffer layer of pre-structured SiC-samples succeeds to make truly nano-scaled pn-junctions. By means of local tunneling spectroscopy the junction width is found to be as narrow as 5 nm which is a hundred times smaller compared to electrically gated structures. The ballistic transmission across the junction is directly proven by systematic transport measurements with a 4-tip STM. Various npn- and pnp-junctions are studied with respect to the barrier length. The pn-junctions are shown to act as polarizer and analyzer with the second junction becoming transparent in case of a fully ballistic barrier. This can be attributed to the almost full suppression of electron transmission through the junction away from normal incidence. PMID:25898259

Baringhaus, Jens; Stöhr, Alexander; Forti, Stiven; Starke, Ulrich; Tegenkamp, Christoph

2015-01-01

301

Gap junction- and hemichannel-independent actions of connexins  

PubMed Central

Connexins have been known to be the protein building blocks of gap junctions and mediate cell–cell communication. In contrast to the conventional dogma, recent evidence suggests that in addition to forming gap junction channels, connexins possess gap junction-independent functions. One important gap junction-independent function for connexins is to serve as the major functional component for hemichannels, the un-apposed halves of gap junctions. Hemichannels, as independent functional units, play roles that are different from that of gap junctions in the cell. The other functions of connexins appear to be gap junction- and hemichannel-independent. Published studies implicate the latter functions of connexins in cell growth, differentiation, tumorigenicity, injury, and apoptosis, although the mechanistic aspects of these actions remain largely unknown. In this review, gap junction- and hemichannel-independent functions of connexins are summarized, and the molecular mechanisms underlying these connexin functions are speculated and discussed. PMID:15955305

Jiang, Jean X.; Gu, Sumin

2007-01-01

302

30 CFR 56.12007 - Junction box connection procedures.  

Code of Federal Regulations, 2014 CFR

...DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Electricity § 56.12007 Junction box connection procedures. Trailing cable and power-cable connections to junction boxes...

2014-07-01

303

30 CFR 56.12007 - Junction box connection procedures.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Electricity § 56.12007 Junction box connection procedures. Trailing cable and power-cable connections to junction boxes...

2010-07-01

304

30 CFR 56.12007 - Junction box connection procedures.  

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Electricity § 56.12007 Junction box connection procedures. Trailing cable and power-cable connections to junction boxes...

2012-07-01

305

Role of gap junction intercellular communication in testicular leydig cell apoptosis induced by oxaliplatin via the mitochondrial pathway.  

PubMed

Platinum agents are widely used in the chemotherapy of testicular cancer. However, adverse reactions and resistance to such agents have limited their application in antineoplastic treatment. The aim of the present study was to determine the role of gap junction intercellular communication (GJIC) composed of Cx43 on oxaliplatin?induced survival/apoptosis in mouse leydig normal and cancer cells using MTT, Annexin V/PI double staining assays and western blot analysis. The results showed that GJIC exerted opposite effects on the mouse leydig cancer (I-10) and normal (TM3) cell apoptosis induced by oxaliplatin. In leydig cancer cells, survival of cells exposed to oxaliplatin was substantially reduced when gap junctions formed as compared to no gap junctions. Pharmacological inhibition of gap junctions by oleamide and 18-?-glycyrrhetinic acid resulted in enhanced survival/decreased apoptosis while enhancement of gap junctions by retinoic acid led to decreased survival/increased apoptosis. These effects occurred only in high?density cultures (gap junction formed), while the pharmacological modulations had no effects when there was no opportunity for gap junction formation. Notably, GJIC played an opposite (protective) role in normal leydig cells survival/apoptosis following exposure to oxaliplatin. Furthermore, this converse oxaliplatin?inducing apoptosis exerted through the functional gap junction was correlated with the mitochondrial pathway?related protein Bcl-2/Bax and caspase?3/9. These results suggested that in testicular leydig normal/cancer cells, GJIC plays an opposite role in oxaliplatin?induced apoptosis via the mitochondrial pathway. PMID:25355463

Tong, Xuhui; Han, Xi; Yu, Binbin; Yu, Meiling; Jiang, Guojun; Ji, Jie; Dong, Shuying

2015-01-01

306

Junctions between i-motif tetramers in supramolecular structures  

PubMed Central

The symmetry of i-motif tetramers gives to cytidine-rich oligonucleotides the capacity to associate into supramolecular structures (sms). In order to determine how the tetramers are linked together in such structures, we have measured by gel filtration chromatography and NMR the formation and dissociation kinetics of sms built by oligonucleotides containing two short C stretches separated by a non-cytidine-base. We show that a stretch of only two cytidines either at the 3?- or 5?-end is long enough to link the tetramers into sms. The analysis of the properties of sms formed by oligonucleotides differing by the length of the oligo-C stretches, the sequence orientation and the nature of the non-C base provides a model of the junction connecting the tetramers in sms. PMID:22362739

Guittet, Eric; Renciuk, Daniel; Leroy, Jean-Louis

2012-01-01

307

Molecular Basis of the Core Structure of Tight Junctions  

PubMed Central

The morphological feature of tight junctions (TJs) fits well with their functions. The core of TJs is a fibril-like proteinaceous structure within the lipid bilayer, the so-called TJ strands. TJ strands in apposing plasma membranes associate with each other to eliminate the intercellular space. A network of paired TJ strands generates a continuous belt that circumscribes each cell to establish the diffusion barrier to the solutes in the paracellular pathway throughout the cellular sheet. Identification and characterization of TJ-associated proteins during the last two decades has unveiled the nature of TJ strands and how they are spatially organized. The interplay between integral membrane proteins, claudins, and cytoplasmic plaque proteins, ZO-1/ZO-2, is critical for TJ formation and function. PMID:20182608

Furuse, Mikio

2010-01-01

308

Evolution of the northern Main Ethiopian rift: birth of a triple junction  

Microsoft Academic Search

Models for the formation of the archetypal rift–rift–rift triple junction in the Afar depression have assumed the synchronous development of the Red Sea–Aden–East African rift systems soon after flood basaltic magmatism at 31 Ma, but the timing of intial rifting in the northern sector of the East African rift system had been poorly constrained. The aims of our field, geochronology,

Ellen Wolfenden; Cynthia Ebinger; Gezahegn Yirgu; Alan Deino; Dereje Ayalew

2004-01-01

309

Photoelectric properties of GaAs p-n-junction under illumination of intense laser radiation  

NASA Astrophysics Data System (ADS)

Results of experimental investigation of photoelectric properties of GaAs p-n-junction illuminated by short laser pulses of 1.06 ?m wavelength are presented. The influence of laser radiation intensity and external bias voltage on the formation of photoresponse voltage has been studied. Free carrier heating was recognized to influence significantly the magnitude of the measured photovoltage. Possibility to improve the conversion efficiency of solar cells is discussed.

Ašmontas, S.; Gradauskas, J.; Sužied?lis, A.; Šil?nas, A.; Vai?ikauskas, V.; Žalys, O.; Steik?nas, G.; Steik?nien?, A.

2014-10-01

310

Autonomic control and innervation of the atrioventricular junctional pacemaker  

E-print Network

Autonomic control and innervation of the atrioventricular junctional pacemaker William J. Hucker junction may be- come the pacemaker of the heart. Unlike the well-characterized sinoatrial node (SAN), autonomic control of the AV junctional pacemaker has not been studied. OBJECTIVE The purpose of this study

311

Overview of the Grand Junction Office from Bluff east of ...  

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

Overview of the Grand Junction Office from Bluff east of facility. Note Buildings #35. #33 and #31A in lower left of photograph. VIEW WEST - Department of Energy, Grand Junction Office, 2597 B3/4 Road, Grand Junction, Mesa County, CO

312

Nonvolatile memory disturbs due to gate and junction leakage currents  

E-print Network

Nonvolatile memory disturbs due to gate and junction leakage currents J.E. Park a,b,*, J. Shields c; accepted 10 September 2002 Abstract We address disturbs due to gate oxide and junction leakage currents in floating gate nonvolatile memories (NVM). The junction leakage is important, because the gate oxide current

Schroder, Dieter K.

313

The epithelial tight junction: Structure, function and preliminary biochemical characterization  

Microsoft Academic Search

The tight junction, or zonula occludens (ZO), forms a semi-permeable barrier in the paracellular pathway in most vertebrate epithelia. The ZO is the apical-most member of a series of intercellular junctions, collectively known as the junctional complex, found at the interface of the apical and lateral cell surface. This structure not only restricts movement of substances around the cells, but

Bruce R. Stevenson; James Melvin Anderson; Stanley Bullivant

1988-01-01

314

Conductance Asymmetry of Graphene p-n Junction  

Microsoft Academic Search

We use the nonequilibrium Green function method in the ballistic limit to provide a quantitative description of the conductance of graphene p-n junctions - an important building block for graphene electronics devices. In this paper, recent experiments on graphene junctions are explained by a ballistic transport model, but only if the finite junction transition width D w is accounted for.

Tony Low; Seokmin Hong; Joerg Appenzeller; Supriyo Datta; Mark S. Lundstrom

2009-01-01

315

Routing Trains Through Railway Junctions: A New Set Packing Approach  

E-print Network

Routing Trains Through Railway Junctions: A New Set Packing Approach Richard Lusby1 , Jesper Larsen The problem of routing trains through railway junctions is an integral part of rail- way operations. Large junctions are highly interconnected networks of track where multiple railway lines meet, intersect

316

76 FR 40293 - Proposed Amendment of Class D and Modification of Class E Airspace; Grand Junction, CO  

Federal Register 2010, 2011, 2012, 2013, 2014

...Modification of Class E Airspace; Grand Junction, CO AGENCY: Federal Aviation Administration...Junction Regional Airport, Grand Junction, CO. Additional controlled airspace is necessary...Junction Regional Airport, Grand Junction, CO. Additional controlled airspace...

2011-07-08

317

Photoelectrochemistry of coreshell tandem junction np+  

E-print Network

for water splitting, an integrated solar fuels device requires catalysts connected to the light absorbers S. Lewis*ab Tandem junction (n­p+ -Si/ITO/WO3/liquid) core­shell microwire devices for solar (anode: tandem device, cathode: Pt disc). The solar energy-conversion efficiencies were very low, 0

Atwater, Harry

318

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

2014-06-10

319

The Molecular Physiology of Tight Junction Pores  

NSDL National Science Digital Library

Tight junctions form selective barriers that regulate paracellular transport across epithelia. A large family of tetraspanning cell-cell adhesion proteins called claudins create the barrier and regulate electrical resistance, size, and ionic charge selectivity. Study of inherited human claudin diseases and the outcome of the genetic manupulation of claudins in mice, Drosophila, and Caenorhabditis elegans are furthering our understanding of paracellular physiology.

Christina M. Van Itallie (University of North Carolina at Chapel Hill Departments of Medicine)

2004-12-01

320

Quantum Junction Solar Cells Jiang Tang,,  

E-print Network

To date, the bandgaps of light-absorbing semiconductors making up multijunction solar cells have been quantum dots offer avenues to inexpensive and robust multijunction solar cell architectures. RecentlyQuantum Junction Solar Cells Jiang Tang,, Huan Liu,, David Zhitomirsky,§ Sjoerd Hoogland,§ Xihua

321

Ureteropelvic junction obstruction presenting after antireflux surgery  

PubMed Central

Ureteropelvic junction obstruction (UPJO) and vesicoureteral reflux (VUR) are two of the most common urologic problems in children that sometimes coexist simultaneously in a patient. However, presentation of UPJO after VUR treatment is rare. We will present two cases and discuss diagnostic and therapeutic aspects of the condition. PMID:23210079

Alizadeh, Farshid; Izadpanahi, Mohammad Hossein; Khorrami, Mohammad Hatef; Nouri-Mahdavi, Kia

2012-01-01

322

Gallium nitride junction field-effect transistor  

DOEpatents

An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

Zolper, John C. (Albuquerque, NM); Shul, Randy J. (Albuquerque, NM)

1999-01-01

323

Gallium nitride junction field-effect transistor  

DOEpatents

An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

Zolper, J.C.; Shul, R.J.

1999-02-02

324

Severely Symptomatic Craniovertebral Junction Abnormalities in Children  

Microsoft Academic Search

Objectives: The treatment of symptomatic cranio-vertebral junction (CVJ) instability in children affected by CVJ abnormalities is a challenge. A series of severely symptomatic children has been reviewed to understand the controversial long-term effectiveness of the aggressive management of CVJ abnormalities, in terms of clinical improvement, spinal stability and growth. Methods: Three Down syndrome patients, 1 with mucopolysaccharidosis and 1 with

Carlo Giussani; Franck-Emmanuel Roux; Paolo Guerra; David Pirillo; Marco Grimaldi; Giuseppe Citerio; Erik P. Sganzerla

2009-01-01

325

Carrier Generation and Recombination in PN Junctions and PN Junction Characteristics  

Microsoft Academic Search

For certain p-n junctions, it has been observed that the measured current-voltage characteristics deviate from the ideal case of the diffusion model. It is the purpose of this paper to show that the current due to generation and recombination of carriers from generation-recombination centers in the space charge region of a p-n junction accounts for the observed characteristics. This phenomenon

Chih-Tang Sah; Robert Noyce; William Shockley

1957-01-01

326

Single molecule junction conductance and binding geometry  

NASA Astrophysics Data System (ADS)

This Thesis addresses the fundamental problem of controlling transport through a metal-organic interface by studying electronic and mechanical properties of single organic molecule-metal junctions. Using a Scanning Tunneling Microscope (STM) we image, probe energy-level alignment and perform STM-based break junction (BJ) measurements on molecules bound to a gold surface. Using Scanning Tunneling Microscope-based break-junction (STM-BJ) techniques, we explore the effect of binding geometry on single-molecule conductance by varying the structure of the molecules, metal-molecule binding chemistry and by applying sub-nanometer manipulation control to the junction. These experiments are performed both in ambient conditions and in ultra high vacuum (UHV) at cryogenic temperatures. First, using STM imaging and scanning tunneling spectroscopy (STS) measurements we explore binding configurations and electronic properties of an amine-terminated benzene derivative on gold. We find that details of metal-molecule binding affect energy-level alignment at the interface. Next, using the STM-BJ technique, we form and rupture metal-molecule-metal junctions ˜104 times to obtain conductance-vs-extension curves and extract most likely conductance values for each molecule. With these measurements, we demonstrated that the control of junction conductance is possible through a choice of metal-molecule binding chemistry and sub-nanometer positioning. First, we show that molecules terminated with amines, sulfides and phosphines bind selectively on gold and therefore demonstrate constant conductance levels even as the junction is elongated and the metal-molecule attachment point is modified. Such well-defined conductance is also obtained with paracyclophane molecules which bind to gold directly through the pi system. Next, we are able to create metal-molecule-metal junctions with more than one reproducible conductance signatures that can be accessed by changing junction geometry. In the case of pyridine-linked molecules, conductance can be reliably switched between two distinct conductance states using sub-nanometer mechanical manipulation. Using a methyl sulfide linker attached to an oligoene backbone, we are able to create a 3-nm-long molecular potentiometer, whose resistance can be tuned exponentially with Angstom-scale modulations in metal-molecule configuration. These experiments points to a new paradigm for attaining reproducible electrical characteristics of metal-organic devices which involves controlling linker-metal chemistry rather than fabricating identically structured metal-molecule interfaces. By choosing a linker group which is either insensitive to or responds reproducibly to changes in metal-molecule configuration, one can design single molecule devices with functionality more complex than a simple resistor. These ambient temperature experiments were combined with UHV conductance measurements performed in a commercial STM on amine-terminated benzene derivatives which conduct through a non-resonant tunneling mechanism, at temperatures varying from 5 to 300 Kelvin. Our results indicate that while amine-gold binding remains selective irrespective of environment, conductance is not temperature independent, in contrast to what is expected for a tunneling mechanism. Furthermore, using temperature-dependent measurements in ambient conditions we find that HOMO-conducting amines and LUMO-conducting pyridines show opposite dependence of conductance on temperature. These results indicate that energy-level alignment between the molecule and the electrodes changes as a result of varying electrode structure at different temperatures. We find that temperature can serve as a knob with which to tune transport properties of single molecule-metal junctions.

Kamenetska, Maria

327

Theoretical consideration of III-V nanowire/Si triple-junction solar cells  

NASA Astrophysics Data System (ADS)

In this paper, we report theoretical consideration and simulation of a proposed III-V nanowire (NW)/Si triple-junction solar cell. The cell consists of two axially connected III-V NW subcells that are grown and electrically integrated on an active Si substrate. The optical properties of the cell are thoroughly analyzed by using the finite-difference time-domain method. It is found that NW subcells with optimized geometry have high absorption throughout their absorption region. Meanwhile, beyond the absorption edge of the top and middle NW subcells, the NWs act as an efficient antireflection coating for the bottom Si subcell due to the formation of an optical cavity within the NW layer. The physics responsible for the enhanced light harvesting process is qualitatively explained through modal analysis. In addition, we have shown that the condition of current matching in a III-V NW/Si multi-junction can be fulfilled by adjusting the diameter of the NWs. In order to study the current-voltage characteristics of the proposed cell, the optical generation profiles under AM1.5G illumination are incorporated into an electrical modeling. Our optoelectrical simulations indicate that, with an excellent current matching between subcells, the performance of the proposed structure is comparable with state-of-the-art multi-junction cells. The results presented here indicate that semiconductor NWs may provide a promising route toward high efficiency multi-junction solar cells.

Wen, Long; Li, Xinhua; Zhao, Zhifei; Bu, Shaojiang; Zeng, XueSong; Huang, Jin-hua; Wang, Yuqi

2012-12-01

328

Indium oxide thin-film homo-junctions: Morphology and electrical properties  

NASA Astrophysics Data System (ADS)

Indium oxide shows an unusual combination of electrical and optical properties that give rise to a broad range of applications in optoelectronic devices. Here, we report results of structural, x-ray photoelectron spectroscopy, and electrical transport studies of transparent homo-junctions, obtained by sequential growth of polycrystalline thin layers of indium oxide under O2-rich and O2-poor conditions. We find that the growth temperature, which affects significantly film morphology, is critical for the rectifying behavior of the junctions. Only junctions grown at about 350 °C are rectifying. We also find that p-type-like layers have higher concentration of inter-grain oxygen than n-type layers, presumably coming from oxygen-rich deposition conditions and from much larger number of grain boundaries than in n-type layers. We conjecture that the segregation of oxygen ions at grain boundaries is responsible for the formation of inversion layers in O2-rich films and their apparent p-type dc conduction. This mechanism significantly modifies the capacitance-voltage characteristics of the junctions. However, the rectifying mechanism can be accounted for by a space-charge layer at the p-n interface. Such behavior might be important in other polycrystalline thin films with a large number of interface defects at grain boundaries.

Stankiewicz, Jolanta; Villuendas, Francisco; Pilar Lozano, María; Díez, Isabel

2013-08-01

329

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

330

The energy barrier at noble metal/TiO2 junctions  

NASA Astrophysics Data System (ADS)

Nobel metal/TiO2 structures are used as catalysts in chemical reactors, active components in TiO2-based electronic devices, and connections between such devices and the outside circuitry. Here, we investigate the energy barrier at the junctions between vacuum-deposited Ag, Au, and Pt thin films and TiO2 layers by recording their electrical current vs. voltage diagrams and spectra of optical responses. Deposited Au/, Pt/, and Ag/TiO2 behave like contacts with zero junction energy barriers, but the thermal annealing of the reverse-biased devices for an hour at 523 K in air converts them to Schottky diodes with high junction energy barriers, decreasing their reverse electric currents up to 106 times. Similar thermal processing in vacuum or pure argon proved ineffective. The highest energy barrier and the lowest reverse current among the devices examined belong to the annealed Ag/TiO2 contacts. The observed electronic features are described based on the physicochemical parameters of the constituting materials. The formation of higher junction barriers with rutile than with anatase is demonstrated.

Hossein-Babaei, F.; Lajvardi, Mehdi M.; Alaei-Sheini, Navid

2015-02-01

331

3D maps of RNA interhelical junctions.  

PubMed

More than 50% of RNA secondary structure is estimated to be A-form helices, which are linked together by various junctions. Here we describe a protocol for computing three interhelical Euler angles describing the relative orientation of helices across RNA junctions. 5' and 3' helices, H1 and H2, respectively, are assigned based on the junction topology. A reference canonical helix is constructed using an appropriate molecular builder software consisting of two continuous idealized A-form helices (iH1 and iH2) with helix axis oriented along the molecular Z-direction running toward the positive direction from iH1 to iH2. The phosphate groups and the carbon and oxygen atoms of the sugars are used to superimpose helix H1 of a target interhelical junction onto the corresponding iH1 of the reference helix. A copy of iH2 is then superimposed onto the resulting H2 helix to generate iH2'. A rotation matrix R is computed, which rotates iH2' into iH2 and expresses the rotation parameters in terms of three Euler angles ?(h), ?(h) and ?(h). The angles are processed to resolve a twofold degeneracy and to select an overall rotation around the axis of the reference helix. The three interhelical Euler angles define clockwise rotations around the 5' (-?(h)) and 3' (?(h)) helices and an interhelical bend angle (?(h)). The angles can be depicted graphically to provide a 'Ramachandran'-type view of RNA global structure that can be used to identify unusual conformations as well as to understand variations due to changes in sequence, junction topology and other parameters. PMID:21959236

Bailor, Maximillian H; Mustoe, Anthony M; Brooks, Charles L; Al-Hashimi, Hashim M

2011-10-01

332

Regulation of Adherens Junctions in Trabecular Meshwork Cells by Rac GTPase and their influence on Intraocular Pressure  

PubMed Central

Intercellular adherens junctions and cell-extracellular matrix interactions are presumed to influence aqueous humor (AH) drainage via the conventional route, however, their direct role in modulation of intraocular pressure (IOP) is not well understood. Here, we investigated the role of Rac GTPase signaling in basal and growth factor-induced formation of adherens junctions in human trabecular meshwork (HTM) cells as compared to human umbilical vascular endothelial cells, and evaluated the effects of inhibition of Rac GTPase activity on IOP in rabbits. Expression of a constitutively active Rac1 GTPase or treatment with platelet derived growth factor (PDGF), a known activator of Rac GTPase, induced formation of ?-catenin-based adherens junctions, actin cytoskeletal reorganization and membrane ruffle in HTM cells. In contrast, treatment of HTM cells with inhibitors of Rac GTPase caused cell-cell separation, a decrease in adherens junctions, and reorganization of actin stress fibers to the cell cortical regions and focal adhesion to the cell leading edges. Both, constitutively active Rac1 and PDGF stimulated generation of Reactive Oxygen Species (ROS) in HTM cells, and ROS were found to increase adherens junction formation and transendothelial electrical resistance (TEER) in HTM cells. Topical application of Rac GTPase inhibitors (EHT1864 and NSC23766), however, only marginally influenced IOP in rabbit eyes. Taken together, these data reveal that while Rac GTPase signaling plays a significant role in regulation of adherens junctions, ROS production and TEER in cells of the AH outflow pathway, Rac inhibitors showed only a marginal influence on IOP in live rabbits. PMID:24932460

Pattabiraman, Padmanabhan P; Epstein, David L; Rao, Ponugoti Vasantha

2013-01-01

333

Atomic and electronic structure of a Rashba p -n junction at the BiTeI surface  

NASA Astrophysics Data System (ADS)

The non-centro-symmetric semiconductor BiTeI exhibits two distinct surface terminations that support spin-split Rashba surface states. Their ambipolarity can be exploited for creating spin-polarized p-n junctions at the boundaries between domains with different surface terminations. We use scanning tunneling microscopy (STM) and spectroscopy (STS) to locate such junctions and investigate their atomic and electronic properties. The Te- and I-terminated surfaces are identified owing to their distinct chemical reactivity and an apparent height mismatch of electronic origin. The Rashba surface states are revealed in the STS spectra by the onset of a van Hove singularity at the band edge. Eventually, an electronic depletion is found on interfacial Te atoms, consistent with the formation of a space-charge area in typical p-n junctions.

Tournier-Colletta, C.; Autès, G.; Kierren, B.; Bugnon, Ph.; Berger, H.; Fagot-Revurat, Y.; Yazyev, O. V.; Grioni, M.; Malterre, D.

2014-02-01

334

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

335

Regulation of gap junctional intercellular communication by TCDD in HMEC and MCF-7 breast cancer cells  

SciTech Connect

Previous studies suggest that many neoplastic tissues exhibit a decrease in gap junctional intercellular communication (GJIC). Many hydrocarbons and organochlorine compounds are environmental pollutants known to be carcinogenic. The effect of an organochlorine compound, TCDD, on GJIC in human breast cell lines has not been established. In the present study, we showed that TCDD causes an inhibition in the gap junctional activity in MCF-7 (breast cancer cells). In MCF-7 cells, an increase in the phosphorylated form of gap junctional protein, connexin 43 (Cx43), and PKC {alpha} was seen in the presence of TCDD. Gap junctional plaque formation was significantly decreased in MCF-7 cells in the presence of TCDD. Immunoprecipitation studies of PKC {alpha} showed that TCDD caused a significant 40% increase in the phosphorylated Cx43 in MCF-7 cells. TCDD also modulated the translocation of PKC {alpha} from the cytosol to the membrane and caused a 2-fold increase in the PKC {alpha} activity at 50 nM TCDD in MCF-7 cells. Calphostin C, an inhibitor of PKC {alpha}, showed a significant inhibition of PKC {alpha} activity in the presence of TCDD. Furthermore, TCDD also caused a decrease in the gap junctional activity and Cx43 protein in human mammary epithelial cells (HMEC). However, we observed a shift in the Cx43 plaques towards the perinuclear membrane in the presence of TCDD by confocal microscopy and Western blot. Overall, these results conclude that TCDD decreases GJIC by phosphorylating Cx43 via PKC {alpha} signaling pathway in MCF-7 cells; however, TCDD decreases the GJIC by affecting the localization of Cx43 in HMEC. These new findings elucidate the differential mode of effect of TCDD in the downregulation of GJIC in HMEC and MCF-7 cells.

Gakhar, Gunjan [Diagnostic Medicine/Pathobiology, 1800 Denison Avenue, Kansas State University, Manhattan, KS 66506 (United States)], E-mail: gunjan@ksu.edu; Schrempp, Diane [Diagnostic Medicine/Pathobiology, 1800 Denison Avenue, Kansas State University, Manhattan, KS 66506 (United States)], E-mail: dschrempp@vet.ksu.edu; Nguyen, Thu Annelise [Diagnostic Medicine/Pathobiology, 1800 Denison Avenue, Kansas State University, Manhattan, KS 66506 (United States)], E-mail: tnguyen@vet.ksu.edu

2009-03-01

336

Te doped ultrabroad band tunnel junction  

NASA Astrophysics Data System (ADS)

A GaInP/AlGaAs broadband tunnel junction (TJ) with a peak current density of 65.3 A/cm2 and an AlGaInP/AlGaAs ultrabroad band TJ with a peak current density of 6.1 A/cm2 were studied and fabricated. Diethyltellurium (DETe) was chosen as an n-type dopant in the TJ. The growth temperature, valve switching and flow variation parameters of DETe were studied for better performance. Measurements, including predoping of DETe before growth and heating up reactor temperature after growth, were taken to deal with the effect of turn-on and off of tellurium. The strain balance method was used to the manage lattice mismatch that was introduced by the tellurium. Various flows of DETe were studied to get the appropriate value needed to fabricate a high peak current density tunnel junction.

Hongbo, Lu; Jingman, Shen; Xinyi, Li; Wei, Zhang; Dayong, Zhou; Lijie, Sun; Kaijian, Chen

2014-10-01

337

Stereoelectronic switching in single-molecule junctions  

NASA Astrophysics Data System (ADS)

A new intersection between reaction chemistry and electronic circuitry is emerging from the ultraminiaturization of electronic devices. Over decades chemists have developed a nuanced understanding of stereoelectronics to establish how the electronic properties of molecules relate to their conformation; the recent advent of single-molecule break-junction techniques provides the means to alter this conformation with a level of control previously unimagined. Here we unite these ideas by demonstrating the first single-molecule switch that operates through a stereoelectronic effect. We demonstrate this behaviour in permethyloligosilanes with methylthiomethyl electrode linkers. The strong ? conjugation in the oligosilane backbone couples the stereoelectronic properties of the sulfur–methylene ? bonds that terminate the molecule. Theoretical calculations support the existence of three distinct dihedral conformations that differ drastically in their electronic character. We can shift between these three species by simply lengthening or compressing the molecular junction, and, in doing so, we can switch conductance digitally between two states.

Su, Timothy A.; Li, Haixing; Steigerwald, Michael L.; Venkataraman, Latha; Nuckolls, Colin

2015-03-01

338

Recent developments in magnetic tunnel junction MRAM  

Microsoft Academic Search

We summarize our progress on Magnetoresistive Random Access Memory (MRAM) based on Magnetic Tunnel Junctions (MTJ). We have demonstrated MTJ material in the 1-1000 k?-?m2 range with MR values above 40%. The switching characteristics are mainly governed by the magnetic shape anisotropy that arises from the element boundaries. The switching repeatability, as well as hard axis selectability, are shown to

S. Tehrani; B. Engel; J. M. Slaughter; E. Chen; M. Deherrera; M. Durlam; P. Naji; R. Whig; J. Janesky; J. Calder

2000-01-01

339

Two-mode dipolar bosonic junctions  

NASA Astrophysics Data System (ADS)

We consider a two-mode atomic Josephson junction realized with dilute dipolar bosons confined by a double-well. We employ the two-site extended Bose-Hubbard Hamiltonian and characterize the ground-state of this system by the Fisher information, coherence visibility, and entanglement entropy. These quantities are studied as functions of the interaction between bosons in different wells. The emergence of Schrödinger's cat-like state with a loss of coherence is also commented.

Mazzarella, G.; Dell'Anna, L.

2013-02-01

340

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

2014-11-12

341

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

342

On the structural organization of isolated bovine lens fiber junctions.  

PubMed

Junctions between fiber cells of bovine lenses have been isolated in milligram quantities, without using detergents or proteases. The structure of the isolated junctions has been studied by thin-section, negative-stain, and freeze-fracture electron microscopy and by x-ray diffraction. The junctions are large and most often have an undulating surface topology as determined by thin sectioning and freeze-fracture. These undulations resemble the tongue-and-groove interdigitations between lens fiber cells previously seen by others (D. H. Dickson and G. W. Crock, 1972, Invest. Ophthalmol. 11:809-815). In sections, the isolated junctions display a pentalamellar structure approximately 13-14 nm in overall thickness, which is significantly thinner than liver gap junctions. Each junctional membrane contains in the plane of the lipid bilayers distinct units arranged in a square lattice with a center-to-center spacing of 6.6 nm. Freeze-fracture replicas of the junctions fractured transversely show that the repeating units extend across the entire thickness of each membrane. Each unit is probably constructed from four identical subunits, with each subunit containing a protein of an apparent molecular weight of 27,000. We conclude that the lens junctions are structurally and chemically, different from gap junctions and could represent a new kind of intercellular contact, not simply another crystalline state of the gap junction protein. PMID:7068755

Zampighi, G; Simon, S A; Robertson, J D; McIntosh, T J; Costello, M J

1982-04-01

343

On the structural organization of isolated bovine lens fiber junctions  

PubMed Central

Junctions between fiber cells of bovine lenses have been isolated in milligram quantities, without using detergents or proteases. The structure of the isolated junctions has been studied by thin-section, negative-stain, and freeze-fracture electron microscopy and by x-ray diffraction. The junctions are large and most often have an undulating surface topology as determined by thin sectioning and freeze-fracture. These undulations resemble the tongue-and-groove interdigitations between lens fiber cells previously seen by others (D. H. Dickson and G. W. Crock, 1972, Invest. Ophthalmol. 11:809-815). In sections, the isolated junctions display a pentalamellar structure approximately 13- 14 nm in overall thickness, which is significantly thinner than liver gap junctions. Each junctional membrane contains in the plane of the lipid bilayers distinct units arranged in a square lattice with a center-to-center spacing of 6.6 nm. Freeze-fracture replicas of the junctions fractured transversely show that the repeating units extend across the entire thickness of each membrane. Each unit is probably constructed from four identical subunits, with each subunit containing a protein of an apparent molecular weight of 27,000. We conclude that the lens junctions are structurally and chemically, different from gap junctions and could represent a new kind of intercellular contact, not simply another crystalline state of the gap junction protein. PMID:7068755

1982-01-01

344

Highly Charged Ion (HCI) Modified Tunnel Junctions  

SciTech Connect

The neutralization energy carried by highly charged ions (HCIs) provides an alternative method for localizing energy on a target's surface, producing features and modifying surfaces with fluences and kinetic energy damage that are negligible compared to singly ionized atoms. Since each HCI can deposit an enormous amount of energy into a small volume of the surface (e.g., Xe{sup 44+} delivers 51 keV of neutralization energy per HCI), each individual HCI's interaction with the target can produce a nanoscale feature. Many studies of HCI-surface features have characterized some basic principles of this unique ion-surface interaction, but the activity reported here has been focused on studying ensembles of HCI features in ultra-thin insulating films by fabricating multi-layer tunnel junction devices. The ultra-thin insulating barriers allow current to flow by tunneling, providing a very sensitive means of detecting changes in the barrier due to highly charged ion irradiation and, conversely, HCI modification provides a method of finely tuning the transparency of the tunnel junctions that spans several orders of magnitude for devices produced from a single process recipe. Systematic variation of junction bias, temperature, magnetic field and other parameters provides determination of the transport mechanism, defect densities, and magnetic properties of these nano-features and this novel approach to device fabrication.

Pomeroy, J. M.; Grube, H. [Atomic Physics Division, National Institute of Standards and Technology (NIST) 100 Bureau Dr., MS 8423, Gaithersburg, MD 20899-8423 (United States)

2009-03-10

345

Josephson junction in a thin film  

SciTech Connect

The phase difference {phi}(y) for a vortex at a line Josephson junction in a thin film attenuates at large distances as a power law, unlike the case of a bulk junction where it approaches exponentially the constant values at infinities. The field of a Josephson vortex is a superposition of fields of standard Pearl vortices distributed along the junction with the line density {phi}'(y)/2{pi}. We study the integral equation for {phi}(y) and show that the phase is sensitive to the ratio l/{Lambda}, where l={lambda}{sub J}{sup 2}/{lambda}{sub L}, {Lambda}=2{lambda}{sub L}{sup 2}/d, {lambda}{sub L}, and {lambda}{sub J} are the London and Josephson penetration depths, and d is the film thickness. For l<<{Lambda}, the vortex ''core'' of the size l is nearly temperature independent, while the phase ''tail'' scales as l{Lambda}/y{sup 2}={lambda}{sub J}2{lambda}{sub L}/d/y{sup 2}; i.e., it diverges as T{yields}T{sub c}. For l>>{Lambda}, both the core and the tail have nearly the same characteristic length l{Lambda}.

Kogan, V. G.; Dobrovitski, V. V.; Clem, J. R.; Mawatari, Yasunori; Mints, R. G.

2001-04-01

346

Josephson Effect in SFNS Josephson Junctions  

NASA Astrophysics Data System (ADS)

The critical current, I C, of Josephson junctions both in ramp-type (S-FN-S) and in overlap (SNF-FN-FNS, SN-FN-NS, SNF-N-FNS) geometries has been calculated in the frame of linearized Usadel equations (S-superconductor, F-ferromagnetic, N-normal metal). For the ramp-type structures, in which S electrodes contact directly the end walls of FN bilayer, it is shown that I C may exhibit damping oscillations as a function of both the distance L between superconductors and thicknesses d F,N of ferromagnetic and normal layers. The conditions have been determined under which the decay length and period of oscillation of I C(L) at fixed d F are of the order of decay length of superconducting correlations in the N metal, ?N, that is much larger than in F film. In overlap configurations, in which S films are placed on the top of NF bilayer, the studied junctions have complex SNF or SN electrodes (N or NF bilayer are situated under a superconductor). We demonstrate that in these geometries the critical current can exceed that in ramp-type junctions. Based on these results, the choice of the most practically applicable geometry is discussed.

Karminskaya, T. Yu.; Kupriyanov, M. Yu.; Golubov, A. A.; Sidorenko, A. S.

347

Single-molecule junctions beyond electronic transport  

NASA Astrophysics Data System (ADS)

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.

Aradhya, Sriharsha V.; Venkataraman, Latha

2013-06-01

348

Primary thermometry with nanoscale tunnel junctions  

SciTech Connect

We have found current-voltage (I-V) and conductance (dI/dV) characteristics of arrays of nanoscale tunnel junctions between normal metal electrodes to exhibit suitable features for primary thermometry. The current through a uniform array depends on the ratio of the thermal energy k{sub B}T and the electrostatic charging energy E{sub c} of the islands between the junctions and is completely blocked by Coulomb repulsion at T=0 and at small voltages eV/2 {<=} Ec. In the opposite limit, k{sub B}T {much_gt} E{sub c}, the width of the conductance minimum scales linearly and universally with T and N, the number of tunnel junctions, and qualifies as a primary thermometer. The zero bias drop in the conductance is proportional to T{sup -1} and can be used as a secondary thermometer. We will show with Monte Carlo simulations how background charge and nonuniformities of the array will affect the thermometer.

Hirvi, K.P.; Kauppinen, J.P.; Paalanen, M.A.; Pekola, J.P. [Univ. of Jyvaskyla (Finland)

1995-10-01

349

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

350

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

351

Electron microscopic single particle analysis of a tetrameric RuvA/RuvB/Holliday junction DNA complex  

SciTech Connect

During the late stage of homologous recombination in prokaryotes, RuvA binds to the Holliday junction intermediate and executes branch migration in association with RuvB. The RuvA subunits form two distinct complexes with the Holliday junction: complex I with the single RuvA tetramer on one side of the four way junction DNA, and complex II with two tetramers on both sides. To investigate the functional roles of complexes I and II, we mutated two residues of RuvA (L125D and E126K) to prevent octamer formation. An electron microscopic analysis indicated that the mutant RuvA/RuvB/Holliday junction DNA complex formed the characteristic tripartite structure, with only one RuvA tetramer bound to one side of the Holliday junction, demonstrating the unexpected stability of this complex. The novel bent images of the complex revealed an intriguing morphological similarity to the structure of SV40 large T antigen, which belongs to the same AAA+ family as RuvB.

Mayanagi, Kouta [Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga 526-0829 (Japan); Takara-Bio Endowed Division, Institute for Protein Research, Osaka University, 6-2-3 Furuedai, Suita, Osaka 565-0874 (Japan); BIRD, JST (Japan)], E-mail: maya@protein.osaka-u.ac.jp; Fujiwara, Yoshie [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Miyata, Tomoko [Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871 (Japan); Morikawa, Kosuke [The Takara-Bio Endowed Division, Institute for Protein Research, Osaka University, 6-2-3 Furuedai, Suita, Osaka 565-0874 (Japan); CREST, JST (Japan)], E-mail: morikako@protein.osaka-u.ac.jp

2008-01-11

352

Modulation of Cell-Cell Junctional Complexes by Matrix Metalloproteinases  

PubMed Central

The ameloblast cell layer of the enamel organ is in contact with the forming enamel as it develops into the hardest substance in the body. Ameloblasts move in groups that slide by one another as the enamel layer thickens. Each ameloblast is responsible for the formation of one enamel rod, and the rods are the mineralized trail that moving ameloblasts leave behind. Matrix metalloproteinases (MMPs) facilitate cell movement in various tissues during development, and in this review we suggest that the tooth-specific MMP, enamelysin (MMP20), facilitates ameloblast movements during enamel development. Mmp20 null mice have thin brittle enamel with disrupted rod patterns that easily abrades from the underlying dentin. Strikingly, the Mmp20 null mouse enamel organ morphology is noticeably dysplastic during late-stage development, when MMP20 is no longer expressed. We suggest that in addition to its role of cleaving enamel matrix proteins, MMP20 also cleaves junctional complexes present on ameloblasts to foster the cell movement necessary for formation of the decussating enamel rod pattern. Therefore, inactivation of MMP20 would result in tight ameloblast cell-cell attachments that may cause maturation-stage enamel organ dysplasia. The tight ameloblast attachments would also preclude the ameloblast movement necessary to form decussating enamel rod patterns. PMID:23053846

Bartlett, J.D.; Smith, C.E.

2013-01-01

353

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

354

Bark beetle controls epithelial morphogenesis by septate junction maturation in Drosophila.  

PubMed

Epithelial tissues separate body compartments with different compositions. Tight junctions (TJs) in vertebrates and septate junctions (SJs) in invertebrates control the paracellular flow of molecules between these compartments. This epithelial barrier function of TJs and SJs must be stably maintained in tissue morphogenesis during cell proliferation and cell movement. Here, we show that Bark beetle (Bark), a putative transmembrane scavenger receptor-like protein, is essential for the maturation but not the establishment of SJs in Drosophila. Embryos that lack bark establish functional SJs, but due to rudimentary septae formation during subsequent embryonic development, these become non-functional. Furthermore, cell adhesion is impaired at the lateral cell membrane and the core protein complexes of SJs are mis-localised, but appear to form otherwise normally in such embryos. We propose a model in which Bark acts as a scaffold protein that mediates cell adhesion and mounting of SJ core complexes during cell rearrangement in tissue morphogenesis. PMID:25704509

Hildebrandt, Anja; Pflanz, Ralf; Behr, Matthias; Tarp, Theresa; Riedel, Dietmar; Schuh, Reinhard

2015-04-15

355

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

356

Junction box wiring and connector durability issues in photovoltaic modules  

NASA Astrophysics Data System (ADS)

We report here on Photovoltaic (PV) module durability issues associated with junction boxes which are under study in Task 10 of the International PV Quality Assurance Task Force (PVQAT). A number of failure modes are being identified in junction boxes in PV arrays in the field which have less than 5 years outdoor operation. Observed failure modes include melted contacts and plastic walls in the junction boxes, separated external connectors and broken latches. Standard IEC and UL tests for modules are designed to expose early mortality failures due to materials selection and design in the assembled module and their impact on performance and safety. Test standards for individual junction box components, when not part of a PV module, are still in development. We will give an overview of the reported field failures associated with junction boxes, and examine standard development as it may impact on testing for durability of junction box connectors over a 25 year life.

Kalejs, Juris

2014-10-01

357

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

358

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

359

Frequency-Locked Submillimeter Wave Generation from Josephson Junction Arrays  

NASA Astrophysics Data System (ADS)

We fabricated a Josephson junction array with an additional inductive coupling line to detect the high frequency and power of Josephson self-radiation. The YBa2Cu3Oy Josephson junctions are fabricated by a pulsed laser deposition method on bicrystal MgO substrates. We measured the submillimeter wave and the Josephson self-radiation power in an external waveguide system. The Josephson junction arrays showed the resistively shunted junction (RSJ)-like current voltage characteristics and good frequency-locking of Josephson self-radiation.As the number of Josephson junctions increased, the maximum detected power was increased. We observed the maximum frequency of above 6 THz for Josephson self-radiation in the array with 11 Josephson junctions from the Shapiro steps under 22 GHz irradiation.

Song, Insang; Park, Kwang-Yong

1999-01-01

360

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

361

Fabrication of magnetic tunnel junctions with epitaxial and textured ferromagnetic layers  

DOEpatents

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

Chang, Y. Austin (Middleton, WI); Yang, Jianhua Joshua (Madison, WI)

2008-11-11

362

Terahertz detector with transmission-line type superconducting tunnel junctions  

Microsoft Academic Search

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

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

2012-01-01

363

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

364

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

365

Realistic design of monolithic, multiple-junction amorphous solar cells  

SciTech Connect

A realistic design for multiple-junction, tandem solar cells based on amorphous materials requires a careful choice of bandgaps and material thicknesses. In this paper, we discuss the influence of material properties on the design of tandem-junction amorphous solar cells, and show that the material properties force a non-optimal design. A two-junction cell based on a-Si and a-(Si,Ge) is shown to be as efficient as a 3-junction cell. We also discuss the stability considerations for tandem cells, and show that appropriate design can lead to greater stability in tandem cells than in single cells.

Dalal, V.L.

1984-05-01

366

Interfacial mixing during annealing of zinc oxide nanoparticle junctions  

NASA Astrophysics Data System (ADS)

The process of forming a junction between crystalline zinc oxide (ZnO) nanoparticles during pulsed thermal annealing in liquid tetradecane is studied using molecular dynamics simulation. Pairs of equal and unequal size particles are considered with emphasis on neck growth and atom mixing. The contact area and interface width of the junction are found to increase with heat pulse power albeit at different rates. The results suggest that it is possible to increase the junction area without significant mixing of atoms across the junction interface by tailoring the heat pulse power.

Hu, Ming; Giapis, Konstantinos P.; Poulikakos, Dimos

2011-05-01

367

Analysis of Y-junction and coupled laser arrays  

SciTech Connect

We demonstrate that a recently developed reformulation of the beam propagation method can be employed to give the exact modal structure of infinite Y-junction laser arrays. Our results for realistically short (approx. =50-..mu..m) Y-junction lengths are similar to those of previous approaches based on perfect Y-junction arrays. However, we find a previously unreported anomalous behavior for the gain of some higher-order supermodes. We also study short and weakly guiding nonideal Y-junction laser arrays. We then describe the behavior of coupled laser arrays in terms of band structure and subsequently propose a new high power strongly coupled laser array configuration.

Hermansson, B.; Yevick, D.

1989-01-01

368

Coherent diffraction of thermal currents in Josephson tunnel junctions  

NASA Astrophysics Data System (ADS)

We theoretically investigate heat transport in temperature-biased Josephson tunnel junctions in the presence of an in-plane magnetic field. In full analogy with the Josephson critical current, the phase-dependent component of the heat flux through the junction displays coherent diffraction. Thermal transport is analyzed in three prototypical junction geometries, highlighting their main differences. Notably, minimization of the Josephson coupling energy requires the quantum phase difference across the junction to undergo ? slips in suitable intervals of magnetic flux. An experimental setup suited to detect thermal diffraction is proposed and analyzed.

Giazotto, F.; Martínez-Pérez, M. J.; Solinas, P.

2013-09-01

369

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

370

Quantum manipulation and simulation using Josephson junction arrays  

E-print Network

We discuss the prospect of using quantum properties of large scale Josephson junction arrays for quantum manipulation and simulation. We study the collective vibrational quantum modes of a Josephson junction array and show that they provide a natural and practical method for realizing a high quality cavity for superconducting qubit based QED. We further demonstrate that by using Josephson junction arrays we can simulate a family of problems concerning spinless electron-phonon and electron-electron interactions. These protocols require no or few controls over the Josephson junction array and are thus relatively easy to realize given currently available technology.

Xingxiang Zhou; Ari Mizel

2006-05-01

371

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

372

Evolutionary analyses of gap junction protein families.  

PubMed

Gap junctions are intercellular channels that link the cytoplasm of neighboring cells in animals, enabling straight passage of ions and small molecules. Two different protein families, pannexins and connexins, form these channels. Pannexins are present in all eumetazoans but echinoderms (and are termed innexins in non-chordates) whereas connexins are exclusive of chordates. Despite little sequence similarity, both types of proteins assemble into a common secondary structure with four hydrophobic transmembrane domains linked by one cytoplasmic and two extracellular loops. Although all pannexins and connexins are packed into hexamers forming single channels, only non-chordate pannexins (innexins) and connexins form gap junctions. Here, we revisit and review evolutionary features of pannexin and connexin protein families. For that, we retrieved members of both families from several complete genome projects, and searched for conserved positions in the independent alignments of pannexin and connexin protein families. In addition, the degree of evolutionary conservation was mapped onto the 3D structure of a connexon (i.e. the assembly of six connexins). Finally, we reconstructed independent phylogenies of pannexins and connexins using probabilistic methods of inference. Non-chordate (Drosophila and Caenorhabditis) pannexins (i.e. innexins) were recovered as sister group of chordate pannexins, which included Ciona paralogs and vertebrate pannexins (pannexin-1 and pannexin-3 were recovered as sister groups to the exclusion of pannexin-2). In the reconstructed phylogeny of connexins, subfamilies ? and ? were recovered as sister groups to the exclusion of subfamily ?, whereas ? and (the newly identified) ? subfamilies were recovered at the base of the tree. A sixth highly divergent subfamily (?) was not included in the phylogenetic analyses. Several groups of paralogy were identified within each subfamily. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions. PMID:22366062

Abascal, Federico; Zardoya, Rafael

2013-01-01

373

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.

374

Si, SiC homo junctions and n-SiC/p-Si hetero junction: MM-wave performance characteristics  

NASA Astrophysics Data System (ADS)

A recent report on realization/studies of Si-SiC hetero junction has given impetus to explore them for generation of rf power in double drift impact ionization avalanche transit time (IMPATT) mode. MM-wave properties of this hetero junction are compared with corresponding Si and SiC homo .junction. Interesting feature of ionization free n-SiC zone localizes the avalanche zone to less than 10% of depletion zone resulting in diode efficiency around 27% (against only 10-15% for both homo junctions Si and SiC) and three fold high rf negative resistance, which can be therefore termed as promising high rf power source.

Pati, S. P.; Tripathy, P. R.; Choudhury, S. K.; Mukharjee, M.; Purohit, P.

2012-10-01

375

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

376

Anatomy and biomechanics of the craniovertebral junction.  

PubMed

The craniovertebral junction (CVJ) has unique anatomical structures that separate it from the subaxial cervical spine. In addition to housing vital neural and vascular structures, the majority of cranial flexion, extension, and axial rotation is accomplished at the CVJ. A complex combination of osseous and ligamentous supports allow for stability despite a large degree of motion. An understanding of anatomy and biomechanics is essential to effectively evaluate and address the various pathological processes that may affect this region. Therefore, the authors present an up-to-date narrative review of CVJ anatomy, normal and pathological biomechanics, and fixation techniques. PMID:25828496

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

2015-04-01

377

Radiation tolerance of vertical junction solar cells  

NASA Technical Reports Server (NTRS)

Extensive radiation testing of vertical junction (VJ) solar cells demonstrated a radiation tolerance better than both planar silicon cells and at least one type of (AlGa)As-GaAs cell. Due to tradeoffs between short circuit current and open circuit voltage, the end of life (10 to the 16th power 1 MeV electrons/sq cm) maximum power point is nearly independent of bulk resistivity between 2 and 10 ohm cm, increases slightly with increasing wafer thickness between 3 and 11 mils, and increases slightly with increasing groove depth between 1 and 3 mils.

Schelnine, A.; Wohlgemuth, J.

1980-01-01

378

Elasticity of a soap film junction  

NASA Astrophysics Data System (ADS)

We investigate the elasticity of an isolated, threefold junction of soap films (Plateau border), which displays static undulations when liquid rapidly flows into it. By analyzing the shape of the Plateau border (thickness R and transverse displacement) as a function of the liquid flow rate Q, we show experimentally and theoretically that the elasticity of the Plateau border is dominated by the bending of the soap films pulling on the Plateau border. In this asymptotic regime, the undulation wavelength obeys the scaling law ˜Q2 R-2 and the decay length ˜Q2 R-4.

Elias, F.; Janiaud, E.; Bacri, J.-C.; Andreotti, B.

2014-03-01

379

Junctional angle of a bihanded helix.  

PubMed

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. PMID:25375538

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

2014-10-01

380

Non-relativistic Josephson junction from holography  

NASA Astrophysics Data System (ADS)

We construct a Josephson junction in non-relativistic case with a Lifshitz geometry as the dual gravity. We investigate the effect of the Lifshitz scaling in comparison with its relativistic counterpart. The standard sinusoidal relation between the current and the phase difference is found for various Lifshitz scalings characterised by the dynamical critical exponent. We also find the exponential decreasing relation between the condensate of the scalar operator within the barrier at zero current and the width of the weak link, as well as the relation between the critical current and the width. Nevertheless, the coherence lengths obtained from two exponential decreasing relations generically have discrepancies for non-relativistic dual.

Li, Huai-Fan; Li, Li; Wang, Yong-Qiang; Zhang, Hai-Qing

2014-12-01

381

Nonintrusive Measurement Of Temperature Of LED Junction  

NASA Technical Reports Server (NTRS)

Temperature inferred from spectrum of emitted light. Method of determining temperature of junction based on two relevant characteristics of LED. Gap between valence and conduction electron-energy bands in LED material decreases with increasing temperature, causing wavelength of emitted photon to increase with temperature. Other, as temperature increases, non-radiative processes dissipate more of input electrical energy as heat and less as photons in band-gap wavelenth region; optical and quantum efficiencies decrease with increasing temperature. In principal, either characteristic alone used to determine temperature. However, desirable to use both to obtain indication of uncertainty.

Leidecker, Henning; Powers, Charles

1991-01-01

382

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Modification of Class E Airspace; Grand Junction, CO AGENCY: Federal Aviation Administration...modifies Class E airspace at Grand Junction, CO. Additional controlled airspace is necessary...controlled airspace at Grand Junction, CO (76 FR 40293). Interested parties...

2011-09-15

383

CHLORAL HYDRATE DECREASES GAP JUNCTION COMMUNICATION IN RAT LIVER EPITHELIAL CELLS  

EPA Science Inventory

Chloral hydrate decreases gap junction communication in rat liver epithelial cells Gap junction communication (GJC) is involved in controlling cell proliferation and differentiation. Connexins (Cx) that make up these junctions are composed of a closely related group of m...

384

Gap junction intercellular communication: a microinjection investigation of fibroblast and epithelial cell lines  

E-print Network

. This forms the complete intercellular channel and is now considered a gap junctional channel. Therefore, a complete gap junctional channel is composed of twelve connexins comprising two connexons. The gap junctional channels cluster together into macular...

Pahlka, Raymond Benton

2002-01-01

385

Rap1 Binds Single-stranded DNA at Telomeric Double- and Single-stranded Junctions and Competes with Cdc13 Protein*  

PubMed Central

The ends of eukaryotic chromosomes are protected by specialized telomere chromatin structures. Rap1 and Cdc13 are essential for the formation of functional telomere chromatin in budding yeast by binding to the double-stranded part and the single-stranded 3? overhang, respectively. We analyzed the binding properties of Saccharomyces castellii Rap1 and Cdc13 to partially single-stranded oligonucleotides, mimicking the junction of the double- and single-stranded DNA (ds-ss junction) at telomeres. We determined the optimal and the minimal DNA setup for a simultaneous binding of Rap1 and Cdc13 at the ds-ss junction. Remarkably, Rap1 is able to bind to a partially single-stranded binding site spanning the ds-ss junction. The binding over the ds-ss junction is anchored in a single double-stranded hemi-site and is stabilized by a sequence-independent interaction of Rap1 with the single-stranded 3? overhang. Thus, Rap1 is able to switch between a sequence-specific and a nonspecific binding mode of one hemi-site. At a ds-ss junction configuration where the two binding sites partially overlap, Rap1 and Cdc13 are competing for the binding. These results shed light on the end protection mechanisms and suggest that Rap1 and Cdc13 act together to ensure the protection of both the 3? and the 5? DNA ends at telomeres. PMID:22075002

Gustafsson, Cecilia; Rhodin Edsö, Jenny; Cohn, Marita

2011-01-01

386

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

387

Intermedin restricts vessel sprouting by inhibiting the loosening of endothelial junction.  

PubMed

Vessel sprouting from pre-existing vasculature is a key step for the formation of a functional vasculature. The low level of vascular endothelial growth factor (VEGF) induces normal and stable angiogenesis, whereas high level of VEGF causes irregular and over sprouted vasculature. Intermedin (IMD) is a novel member of calcitonin family, and was found to be able to restrict the excessive vessel sprouting. However, the underlying mechanism had not been elucidated. In this study, using in vitro and in vivo angiogenic models, we found that the loosening of endothelial junction could significantly increase the ability of low-dose VEGF to induce vessel sprouting. IMD inhibited the junction dissociation-induced vessel sprouting by re-establishing the complex of vascular endothelial cadherin on the cell-cell contact. Our findings suggested a novel mechanism through which IMD could restrict the excessive vessel sprouting by preventing the endothelial junction from dissociation, and provide new insight into the understanding of the regulation of sprouting angiogenesis. PMID:25637664

Xiao, Fei; Wang, Li-Jun; Zhao, Huan; Tan, Chun; Wang, De-Nian; Zhang, Heng; Wei, Yong-Gang; Liu, Jin; Zhang, Wei

2015-02-27

388

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

389

Tricellulin regulates junctional tension of epithelial cells at tricellular contacts through Cdc42.  

PubMed

When the surface view of each epithelial cell is compared with a polygon, its sides correspond to cell-cell junctions, whereas its vertices correspond to tricellular contacts, whose roles in epithelial cell morphogenesis have not been well studied. Here, we show that tricellulin (also known as MARVELD2), which is localized at tricellular contacts, regulates F-actin organization through Cdc42. Tricellulin-knockdown epithelial cells exhibit irregular polygonal shapes with curved cell borders and impaired organization of F-actin fibers around tricellular contacts during cell-cell junction formation. The N-terminal cytoplasmic domain of tricellulin binds to the Cdc42 guanine-nucleotide-exchange factor (GEF) Tuba (also known as DNMBP and ARHGEF36), and activates Cdc42. A tricellulin mutant that lacks the ability to bind Tuba cannot rescue the curved cell border phenotype of tricellulin-knockdown cells. These findings indicate that tricellular contacts play crucial roles in regulating the actomyosin-mediated apical junctional complex tension through the tricellulin-Tuba-Cdc42 system. PMID:25097232

Oda, Yukako; Otani, Tetsuhisa; Ikenouchi, Junichi; Furuse, Mikio

2014-10-01

390

Osteocytes up-regulate the terminal differentiation of pre-osteoblasts via gap junctions.  

PubMed

We examined cell-to-cell interaction between pre-osteoblasts and osteocytes using MC3T3-E1 and MLO-Y4, respectively. First, GFP expressing MC3T3-E1 (E1-GFP) cells were generated to isolate the cells from co-culture with MLO-Y4. No changes were observed in the expression of osteogenic transcription factors Runx2, Osterix, Dlx5 and Msx2, but expression of alkaline phosphatase (ALP) and bone sialoprotein (BSP) in E1-GFP co-cultured with MLO-Y4 was 300-400-fold greater than that in mono-cultured E1-GFP. In addition, mineralized nodule formation was drastically increased in co-cultured E1-GFP cells compared to mono-cultured cells. Patch clamp assay showed the presence of gap junctions between E1-GFP and MLO-Y4. Furthermore, when the gap junction inhibitor carbenoxolone (CBX) was added to the culture, increased expression of ALP and BSP in E1-GFP co-cultured with MLO-Y4 was suppressed. These results suggest that gap junction detected between pre-osteoblasts and osteocytes plays an important role on the terminal differentiation of pre-osteoblasts. PMID:25450679

Nishikawa, Yoichi; Akiyama, Yuko; Yamamoto, Kiyofumi; Kobayashi, Masayuki; Watanabe, Eri; Watanabe, Nobukazu; Shimizu, Noriyoshi; Mikami, Yoshikazu; Komiyama, Kazuo

2015-01-01

391

Spin Torque in Magnetic Tunnel Junctions  

NASA Astrophysics Data System (ADS)

The effect of current-induced switching in the orientation of magnetic moments has attracted much attention both experimentally[1] and theoretically in the past several years due to its potential application to spin electronics. The origin of the current-induced switching is the spin torque due to the local exchange interactions between the conduction electrons and the magnetic moments. Using a simple tight-binding Hamiltonian[2] for the magnetic metal-insulator-magnetic metal tunneling junction and the Keldysh formalism for the non-equilibrium Green functions, we have calculated the spin torque and the tunneling current in non-collinear magnetic junctions. We have studied the effect of the bias voltage, the thickness of the barrier and the angle between the magnetizations of the ferromagnetic electrodes on the spin torque and the tunneling current. *E. Myers, D. Ralph, J. Katine, R. Louie, R. Buhrman, Science 285, 867 (1999). *C. Caroli, R. Combescot, P. Nozieres, D. Saint-James, J. Phys. C: Solid St. Phys., 4, 916 (1971). *Supported through the NSF grant No. DMR-0097187

Kalitsov, Alan; Butler, William

2005-03-01

392

Electrophysiological study in neuromuscular junction disorders  

PubMed Central

This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS), congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG) helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS). SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation. PMID:23661960

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

2013-01-01

393

Interfacial effects in magnetic tunneling junctions  

NASA Astrophysics Data System (ADS)

Magnetic tunneling junctions (MTJ) have a rich background in physics that is only beginning to be understood. MTJs a useful probe into physics at the nanoscale level. There are new physics arising from the study of MTJs, such as the effect of spin asymmetry within the ferromagnetic electrodes. Additionally, with the increasingly smaller length scales involved, the physics of the interfaces as compared to the bulk are becoming more critical, and processes such as interfacial charge accumulation begin to manifest themselves. Magnetic tunneling junctions also show much promise for applications as varied as non-volatile random access memory, hard drive read heads, and magnetic field sensors. Before they may be successfully implemented in electronics, it will be necessary to completely understand the underlying physics of their operation. This thesis discusses methods of analyzing the properties of the barrier layer, and its interfaces through transport measurements. This process is facilitated by the implementation of a new fabrication method that allows a series of MTJs to be fabricated with incremental changes to one fabrication parameter along the series. The results of these measurements shed new light onto the process of tunneling. The results discussed herein focus on spin polarized tunneling and how this process is affected by the oxidation level of the barrier, properties of different electrode materials such as work function and density of states, and interfacial charge accumulation.

Landry, Glen Alex

394

Fabrication of Niobium Nanobridge Josephson Junctions  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

395

Dynamics of domain wall networks with junctions  

SciTech Connect

We use a combination of analytic tools and an extensive set of the largest and most accurate three-dimensional field theory numerical simulations to study the dynamics of domain wall networks with junctions. We build upon our previous work and consider a class of models which, in the limit of large number N of coupled scalar fields, approaches the so-called ''ideal'' model (in terms of its potential to lead to network frustration). We consider values of N between N=2 and N=20, and a range of cosmological epochs, and we also compare this class of models with other toy models used in the past. In all cases we find compelling evidence for a gradual approach to scaling, strongly supporting our no-frustration conjecture. We also discuss the various possible types of junctions (including cases where there is a hierarchy of them) and their roles in the dynamics of the network. Finally, we provide a cosmological Zel'dovich-type bound on the energy scale of this kind of defect network: it must be lower than 10 keV.

Avelino, P. P.; Oliveira, J. C. R. E. [Centro de Fisica do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Departamento de Fisica da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Martins, C. J. A. P. [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas s/n, 4150-762 Porto (Portugal); DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Menezes, J. [Centro de Fisica do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Centro de Astrofisica da Universidade do Porto, Rua das Estrelas s/n, 4150-762 Porto (Portugal); Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil); Menezes, R. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil)

2008-11-15

396

Quantum tunneling across a domain wall junction (abstract)  

Microsoft Academic Search

In this paper, we discuss a system that is appropriately called a ‘‘domain wall junction’’ (DWJ). The DWJ is a close analog of the Josephson junction with respect to the usefulness of both systems in studying switching by thermal activation (TA) and by quantum tunneling (QT). What makes this system especially attractive for experimental and theoretical studies is that it

Bernard Barbara; Leon Gunther

1994-01-01

397

Quantum tunneling across a domain-wall junction  

Microsoft Academic Search

In this article, we discuss a system that is appropriately called a domain-wall junction (DWJ). The DWJ is a close analog of the Josephson junction with respect to the usefulness of both systems in studying switching by thermal activation (TA) and by quantum tunneling (QT). We will show through theoretical analysis that it is within our means to fabricate a

Leon Gunther; Bernard Barbara

1994-01-01

398

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

399

Low resistance junctions in crayfish: structural changes with functional uncoupling  

E-print Network

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

Camillo Peracchia; Angela F. Dulhunty

1976-01-01

400

VORTEX PROPAGATION AND RADIATION EMISSION IN JOSEPHSON TUNNEL JUNCTIONS  

E-print Network

the voltage-frequency relation eV = hf, as predicted by the vortex-motion picture. Some aspects of radiation the rf fields distort the antenna pattern. 2. Large 7c junctions and vortex motion. - In these previous299 VORTEX PROPAGATION AND RADIATION EMISSION IN JOSEPHSON TUNNEL JUNCTIONS T. A. FULTON and L. N

Boyer, Edmond

401

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...

402

JUNCTIONS BETWEEN INTIMATELY APPOSED CELL MEMBRANES IN THE VERTEBRATE BRAIN  

Microsoft Academic Search

Certain junctions between ependymal cells, between astrocytes, and between some elec- trically coupled neurons have heretofore been regarded as tight, pentalaminar occlusions of the intercellular cleft. These junctions are now redefined in terms of their configuration after treatment of brain tissue in uranyl acetate before dehydration. Instead of a median dense lamina, they are bisected by a median gap 20-30

M. W. Brightman; T. S. REESE

1969-01-01

403

10. VIEW UPSTREAM OF PIPELINE SECTION AT JUNCTION OF HUME ...  

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

10. VIEW UPSTREAM OF PIPELINE SECTION AT JUNCTION OF HUME CEMENT PIPE AND CAST-IRON (460'). NOTE CYLINDRICAL COLLAR OF CEMENT SECTIONS AND BELL JUNCTIONS OF IRON PIPE. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

404

Dynamic Control of Tunneling Conductance in Ferroelectric Tunnel Junctions  

NASA Astrophysics Data System (ADS)

We investigate the dynamic characteristics of electric polarization P(t) in a ferroelectric junction under ac applied voltage and stress, and calculate the frequency response and the cut-off frequency f0, which provides a reference for the upper limit of the working frequency. Our study might be significant for sensor and memory applications of nanodevices based on ferroelectric junctions.

Zou, Ya-Yi; Chew, Khian-Hooi; Zhou, Yan

2013-10-01

405

Spin and valley transports in junctions of Dirac fermions  

NASA Astrophysics Data System (ADS)

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

Yokoyama, Takehito

2014-08-01

406

Characterization of NbN films and tunnel junctions  

NASA Technical Reports Server (NTRS)

Properties of NbN films and NbN/MgO/NbN tunnel junctions are discussed. NbN junctions are being developed for use in high-frequency, SIS quasiparticle mixers. To properly design mixer circuits, junction and film properties need to be characterized. The specific capacitance of NbN/MgO/NbN junctions has been measured as a function of the product of the normal-state resistance and the junction area (RnA), and it is found to vary by more than a factor of two (35-85 fF/sq microns) over the range of RnA measured (1000-50 ohm sq microns). This variation is important because the specific capacitance determines the RC speed of the tunnel junction at a given RnA value. The magnetic penetration depth of NbN films deposited under different conditions is also measured. The magnetic penetration depth affects the design of microstrip line used in RF tuning circuits. Control of the magnetic penetration depth is necessary to fabricate reproducible tuning circuits. Additionally, the critical current uniformity for arrays of 100 junctions has been measured. Junction uniformity will affect the design of focal-plane arrays of SIS mixers. Finally, the relevance of these measurements to the design of Josephson electronics is discussed.

Stern, J. A.; Leduc, H. G.

1991-01-01

407

Claudins and the Modulation of Tight Junction Permeability  

PubMed Central

Claudins are tight junction membrane proteins that are expressed in epithelia and endothelia and form paracellular barriers and pores that determine tight junction permeability. This review summarizes our current knowledge of this large protein family and discusses recent advances in our understanding of their structure and physiological functions. PMID:23589827

Günzel, Dorothee

2013-01-01

408

The intercellular junctional complexes of retinal pigment epithelia  

Microsoft Academic Search

Previous studies of the retinal pigment epithelium have suggested that its cells are inter- connected by typical arrays of intercellular junctions. Using both conventional and freeze- fracture electron microscopy, we have found on the contrary that pigment epithelial cells in a wide variety of vertebrates (goldfish, frog, newt, mudpuppy, turtle, chicken, mouse, cat, and monkey) in fact have unusual junctional

Albert J. Hudspeth; Ann G. Yee

1973-01-01

409

Dc SQUID based on unshunted Josephson junctions: experimental results  

Microsoft Academic Search

It has been proposed that a new SQUID type be constructed by using unshunted Josephson junctions instead of resistively shunted junctions. Using this approach we are able to present a SQUID having a high output dynamic resistance and a device characterized by a negative output resistance and an extremely low noise. The first mentioned is called a high-gain SQUID, the

H. Seppa; M. Kiviranta; L. Gronberg

1995-01-01

410

5. JUNCTION OF NORTH AND SOUTH FORK TULE RIVER MIDDLE ...  

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

5. JUNCTION OF NORTH AND SOUTH FORK TULE RIVER MIDDLE FORK BRANCH FLUMES SHOWING SPILLWAY VALVES ON EACH FLUME, CONCRETE SANDBOX AT JUNCTION (SPILLING WATER), AND FLUME CONTROL HOUSE AND FISH WHEEL AT UPPER PHOTO LEFT. VIEW TO NORTHWEST. - Tule River Hydroelectric Project, Water Conveyance System, Middle Fork Tule River, Springville, Tulare County, CA

411

Alternative Conformations of a Nucleic Acid Four-way Junction  

E-print Network

was solved at 3.1 AÃ? resolution. The structure of the junction differs substantially from the ``stacked are dynamic structures capable of under- going large conformational changes. Reported crys- tal structures of an all-DNA four-way junction complexed with either Cre or RuvA recombinase reveal a substantial change

Stout, Charles D.

412

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

413

Gap Junction Structures. IV. Revealed by Low-irradiation  

E-print Network

Gap Junction Structures. IV. Revealed by Low-irradiation Asymmetric Microscopy Features T. S. BAKER concentration at six symmetrically related sites ~34 tk from the connexon center, 8° to the right or left of the (1, 1) lattice vector may reveal an intrinsic asymmetric feature of the junction structure

Baker, Timothy S.

414

Resistance switch employing a simple metal nanogap junction  

Microsoft Academic Search

In recent years, several researchers have reported the occurrence of reversible resistance switching effects in simple metal nanogap junctions. A large negative resistance is observed in the I-V characteristics of such a junction when high-bias voltages are applied. This phenomenon is characteristic behaviour on the nanometre scale; it only occurs for gap widths slightly under 13 nm. Furthermore, such a

Yasuhisa Naitoh; Masayo Horikawa; Hidekazu Abe; Tetsuo Shimizu

2006-01-01

415

Negative differential resistance effect in planar graphene nanoribbon break junctions  

NASA Astrophysics Data System (ADS)

Graphene is an interesting material with a number of desirable electrical properties. Graphene-based negative differential resistance (NDR) devices hold great potential for enabling the implementation of several elements required in electronic circuits and systems. In this article we propose a novel device structure that exhibits NDR using single layer graphene that is able to be fabricated using standard lithography techniques. Using theoretical simulation, we show that graphene nanoribbon (GNR) junctions exhibit NDR effect if a gap is introduced in the structure in the transport direction of the ribbon. Using standard lithography techniques, we produce a GNR and use electro-migration to create a nanogap by breaking the GNR device. Scanning electron microscopy images show the formation of a tunnel gap. The predicted NDR phenomenon is experimentally verified in the current-voltage characteristic of the device. The linear and non-linear characteristics of the I-V responses before and after breakdown confirm that the NDR effect arises from the tunnel gap.

Nguyen, Phuong Duc; Nguyen, Thanh Cong; Hossain, Faruque M.; Huynh, Duc Hau; Evans, Robin; Skafidas, Efstratios

2014-11-01

416

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

417

Parametric resonance in the system of long Josephson junctions  

NASA Astrophysics Data System (ADS)

The phase dynamics of the system of long Josephson junctions whose length exceeds the Josephson penetration depth has been studied. The possibility of the appearance of a longitudinal plasma wave and parametric resonance has been demonstrated. Both inductive and capacitive couplings between Josephson junctions have been taken into account in the calculations. The current-voltage characteristics, as well as time evolution of the spatial distribution of the electric charge in superconducting layers and the magnetic field, have been calculated in all Josephson junctions of the system. The coexistence of the longitudinal plasma wave and fluxon states has been observed in the region of parametric resonance beginning with a certain length of the Josephson junction. This indicates the appearance of a new unique collective excitation in the system of coupled Josephson junctions, namely, a composite state of the Josephson current, electric field, and vortex magnetic field.

Rahmonov, I. R.; Shukrinov, Yu. M.; Irie, A.

2014-08-01

418

190-GHz radiation from a quasioptical Josephson junction array  

NASA Technical Reports Server (NTRS)

At 190 GHz, 0.36 micro W has been detected from an 11 x 58 array of niobium Josephson junctions. The power is radiated directly into free space above the surface of the two-dimensional array of junctions. Detection is made by a commercial bolometer outside the array cryostat. The junctions in the array are closely spaced in the y-dimension, but spaced by more than one-half wavelength in the x-direction. This asymmetry results in mutual phase-locking between adjacent junctions suitable for the production of y-polarized radiation. The resonance and asymmetry also result in a reasonable impedance match between the Josephson junctions and the free-space radiation mode.

Wengler, Michael J.; Guan, Boran; Track, Elie K.

1995-01-01

419

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

420

III-nitride tunnel junctions for efficient solid state lighting  

NASA Astrophysics Data System (ADS)

We discuss the design and demonstration ultra-low resistance III-nitride tunnel junctions, and how tunnel junctions could solve the long-standing problem of efficiency droop in solid state lighting. We have used nanoscale band engineering based on polarization and mid-gap states to reduce tunneling resistance by four orders of magnitude. We will discuss experimental demonstration of highly efficient tunnel junctions (resistivity ~ 0.1 mOhm-cm2) in PN junctions, p-contact free LEDs, and multiple junction structures. Finally we will show how tunneling based carrier regeneration in multiple active region cascade LEDs could help to enable low current, high voltage operation to overcome the efficiency droop problem.

Krishnamoorthy, Sriram; Akyol, Fatih; Rajan, Siddharth

2014-03-01

421

Spectral and power properties of inline long Josephson junctions  

NASA Astrophysics Data System (ADS)

Spectral and power properties of inline long Josephson junctions operating in a flux flow regime are investigated using direct computer simulation of the sine-Gordon equation with a noise source. Good agreement of simulation results with the formula for the linewidth [Pankratov, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.65.054504 65, 054504 (2002)] is achieved. The comparison with long Josephson junction of overlap geometry is performed. It is demonstrated that the inline junction has the linewidth which is by a factor of 2 larger than the overlap junction, while the maximal oscillation power is roughly the same in spite of the fact that the velocity-matching step height of the inline junction is much smaller than that of the overlap one.

Revin, Leonid S.; Pankratov, Andrey L.

2012-08-01

422

Nonsense-mediated translational repression involves exon junction complex downstream of premature translation termination codon.  

PubMed

Human transforming growth factor-beta receptor type 2 (TGFbetaR2) mRNA harboring a premature translation termination codon (PTC) generated by frameshift mutation is targeted for nonsense-mediated translational repression (NMTR), rather than nonsense-mediated mRNA decay (NMD). Here we show that exon junction complex (EJC) downstream of a PTC plays an inhibitory role in translation of TGFbetaR2 mRNA. Translational repression by core EJC components occurs after formation of 80S ribosome complex, which is demonstrated using different types of internal ribosome entry sites (IRESes). Our findings implicate EJCs or core EJC components as negative regulators of translation. PMID:20067791

Lee, Hyung Chul; Oh, Nara; Cho, Hana; Choe, Junho; Kim, Yoon Ki

2010-02-19

423

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

424

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

PubMed

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

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

2015-03-01

425

Age-related changes in gap junctional intercellular communication in osteoblastic cells.  

PubMed

Aging demonstrates deleterious effects upon the skeleton which can predispose an individual to osteoporosis and related fractures. Despite the well-documented evidence that aging decreases bone formation, there remains little understanding whereby cellular aging alters skeletal homeostasis. We, and others, have previously demonstrated that gap junctions--membrane-spanning channels that allow direct cell-to-cell conductance of small signaling molecules--are critically involved in osteoblast differentiation and skeletal homeostasis. We examined whether the capacity of rat osteoblastic cells to form gap junctions and respond to known modulators of gap junction intercellular communication (GJIC) was dependent on the age of the animal from which they were isolated. We observed no effect of age upon osteoblastic Cx43 mRNA, protein or GJIC. We also examined age-related changes in PTH-stimulated GJIC. PTH demonstrated age-dependent effects upon GJIC: Osteoblastic cells from young rats increased GJIC in response to PTH, whereas there was no change in GJIC in response to PTH in osteoblastic cells from mature or old rats. PTH-stimulated GJIC occurred independently of changes in Cx43 mRNA or protein expression. Cholera toxin significantly increased GJIC in osteoblastic cells from young rats compared to those from mature and old rats. These data demonstrate an age-related impairment in the capacity of osteoblastic cells to generate functional gap junctions in response to PTH, and suggest that an age-related defect in G protein-coupled adenylate cyclase activity at least partially contributes to decreased PTH-stimulated GJIC. PMID:22696456

Genetos, Damian C; Zhou, Zhiyi; Li, Zhongyong; Donahue, Henry J

2012-12-01

426

Junction Conditions and Consequences of Quasi-Spherical Space-Time with Electro-Magnetic Field and Vaidya Matric  

E-print Network

In this work the junction conditions between the exterior Reissner-Nordstrom-Vaidya space-time with the interior quasi-spherical Szekeres space-time have been studied for analyzing gravitational collapse in the presence of a magneto-hydrodynamic fluid undergoing dissipation in the form of heat flow. We have discussed about the apparent horizon and have evaluated the time difference between the formation of apparent horizon and central singularity.

Nath, Soma; Chakraborty, Subenoy

2007-01-01

427

Junction Conditions and Consequences of Quasi-Spherical Space-Time with Electro-Magnetic Field and Vaidya Matric  

E-print Network

In this work the junction conditions between the exterior Reissner-Nordstrom-Vaidya space-time with the interior quasi-spherical Szekeres space-time have been studied for analyzing gravitational collapse in the presence of a magneto-hydrodynamic fluid undergoing dissipation in the form of heat flow. We have discussed about the apparent horizon and have evaluated the time difference between the formation of apparent horizon and central singularity.

Soma Nath; Ujjal Debnath; Subenoy Chakraborty

2007-11-07

428

Switch in gap junction protein expression is associated with selective changes in junctional permeability during keratinocyte differentiation.  

PubMed Central

Gap junctional communication provides a mechanism for regulating multicellular activities by allowing the exchange of small diffusible molecules between neighboring cells. The diversity of gap junction proteins may exist to form channels that have different permeability properties. We report here that induction of terminal differentiation in mouse primary keratinocytes by calcium results in a specific switch in gap junction protein expression. Expression of alpha 1 (connexin 43) and beta 2 (connexin 26) gap junction proteins is down-modulated, whereas that of beta 3 (connexin 31) and beta 4 (connexin 31.1) proteins is induced. Although both proliferating and differentiating keratinocytes are electrically coupled, there are significant changes in the permeability properties of the junctions to small molecules. In parallel with the changes in gap junction protein expression during differentiation, the intercellular transfer of the small dyes neurobiotin, carboxyfluorescein, and Lucifer yellow is significantly reduced, whereas that of small metabolites, such as nucleotides and amino acids, proceeds unimpeded. Thus, a switch in gap junction protein expression in differentiating keratinocytes is accompanied by selective changes in junctional permeability that may play an important role in the coordinate control of the differentiation process. Images PMID:8022804

Brissette, J L; Kumar, N M; Gilula, N B; Hall, J E; Dotto, G P

1994-01-01

429

The Loss of Cellular Junctions in Epithelial Lung Cells Induced by Cigarette Smoke Is Attenuated by Corilagin  

PubMed Central

Cigarette smoke (CS) contains over 4700 compounds, many of which can affect cellular redox balance through free radicals production or through the modulation of antioxidant enzymes. The respiratory tract is one of the organs directly exposed to CS and it is known that CS can damage the integrity of lung epithelium by affecting cell junctions and increasing epithelium permeability. In this study, we have used a human lung epithelial cell line, Calu-3, to evaluate the effect of CS on lung epithelial cell junctions levels, with special focus on the expression of two proteins involved in intercellular communication: connexins (Cx) 40 and 43. CS exposure increased Cx40 gene expression but not of Cx43. CS also induced NF?B activation and the formation of 4HNE-Cxs adducts. Since corilagin, a natural polyphenol, is able to inhibit NF?B activation, we have determined whether corilagin could counteract the effect of CS on Cxs expression. Corilagin was able to diminish CS induced Cx40 gene expression, 4HNE-Cx40 adducts formation, and NF?B activation. The results of this study demonstrated that CS induced the loss of cellular junctions in lung epithelium, possibly as a consequence of Cx-4HNE adducts formation, and corilagin seems to be able to abolish these CS induced alterations. PMID:25802682

Muresan, Ximena M.; Cervellati, Franco; Sticozzi, Claudia; Belmonte, Giuseppe; Chui, Chung Hin; Lampronti, Ilaria; Borgatti, Monica; Gambari, Roberto

2015-01-01

430

VEGF and Angiopoietin-1 exert opposing effects on cell junctions by regulating the Rho GEF Syx.  

PubMed

Vascular endothelial growth factor (VEGF) and Ang1 (Angiopoietin-1) have opposing effects on vascular permeability, but the molecular basis of these effects is not fully known. We report in this paper that VEGF and Ang1 regulate endothelial cell (EC) junctions by determining the localization of the RhoA-specific guanine nucleotide exchange factor Syx. Syx was recruited to junctions by members of the Crumbs polarity complex and promoted junction integrity by activating Diaphanous. VEGF caused translocation of Syx from cell junctions, promoting junction disassembly, whereas Ang1 maintained Syx at the junctions, inducing junction stabilization. The VEGF-induced translocation of Syx from EC junctions was caused by PKD1 (protein kinase D1)-mediated phosphorylation of Syx at Ser(806), which reduced Syx association to its junctional anchors. In support of the pivotal role of Syx in regulating EC junctions, syx(-/-) mice had defective junctions, resulting in vascular leakiness, edema, and impaired heart function. PMID:23253477

Ngok, Siu P; Geyer, Rory; Liu, Miaoliang; Kourtidis, Antonis; Agrawal, Sudesh; Wu, Chuanshen; Seerapu, Himabindu Reddy; Lewis-Tuffin, Laura J; Moodie, Karen L; Huveldt, Deborah; Marx, Ruth; Baraban, Jay M; Storz, Peter; Horowitz, Arie; Anastasiadis, Panos Z

2012-12-24

431

Low cost solar array project: Cell and module formation research area. Process research of non-CZ silicon material  

NASA Technical Reports Server (NTRS)

Meniscus coates tests, back junction formation using a new boron containing liquid, tests of various SiO2 and boron containing liquids, pelletized silicon for replenishment during web growth, and ion implantation compatibility/feasibility study are discussed.

1983-01-01

432

Ultimately short ballistic vertical graphene Josephson junctions  

PubMed Central

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale. PMID:25635386

Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

2015-01-01

433

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

434

Trypanosoma cruzi alters adherens junctions in cardiomyocytes.  

PubMed

We analyzed the distribution and expression of cadherin and beta-catenin during Trypanosoma cruzi-cardiomyocyte interaction. Confocal microscopy revealed cadherin associated with beta-catenin at the cell-cell contacts. After 24h of infection, the spatial distribution and expression of both adherens junction (AJ) proteins remained unaltered. In contrast, loss of N-cadherin-catenin complex was visualized in highly infected cardiomyocytes. Immunoblotting assays corroborated the spatial disorder, showing a 46% reduction in both N-cadherin and beta-catenin expression at later infection (72h of infection). Our data demonstrate that T. cruzi infection disturbs AJs, which can result in loss of cardiac tension and may contribute to the cardiac dysfunctions present in T. cruzi infection. PMID:18778790

de Melo, Tatiana G; Meirelles, Maria de Nazareth S L; Pereira, Mirian Claudia S

2008-10-01

435

Ultimately short ballistic vertical graphene Josephson junctions  

NASA Astrophysics Data System (ADS)

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale.

Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

2015-01-01

436

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

437

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

438

Advanced Concepts in Josephson Junction Reflection Amplifiers  

NASA Astrophysics Data System (ADS)

Low-noise amplification at microwave frequencies has become increasingly important for the research related to superconducting qubits and nanoelectromechanical systems. The fundamental limit of added noise by a phase-preserving amplifier is the standard quantum limit, often expressed as noise temperature . Towards the goal of the quantum limit, we have developed an amplifier based on intrinsic negative resistance of a selectively damped Josephson junction. Here we present measurement results on previously proposed wide-band microwave amplification and discuss the challenges for improvements on the existing designs. We have also studied flux-pumped metamaterial-based parametric amplifiers, whose operating frequency can be widely tuned by external DC-flux, and demonstrate operation at pumping, in contrast to the typical metamaterial amplifiers pumped via signal lines at.

Lähteenmäki, Pasi; Vesterinen, Visa; Hassel, Juha; Paraoanu, G. S.; Seppä, Heikki; Hakonen, Pertti

2014-06-01

439

Outcome of antenatally diagnosed pelviureteric junction hydronephrosis.  

PubMed

Over a 6-year period, in a series of 107 consecutive patients with antenatally detected urological anomalies, 45 had pelviureteric junction (PUJ) hydronephrosis (66 units). Of these, 24 units (36%) had obstructive (group I) and 42 (64%) non-obstructive hydronephrosis (group II). Significantly compromised renal function was found only in group I. Treatment in group I was by an early pyeloplasty; in group II the patients were kept under close review. During the 6-year period, 2 units (5%) in group II, deteriorated, 13 (31%) improved and 27 (64%) were unchanged. These results suggest that early in life, antenatally diagnosed PUJ hydronephrosis without obstruction may be a relatively benign condition but will require long-term follow-up in order to determine the natural history of the condition. PMID:1993284

Najmaldin, A S; Burge, D M; Atwell, J D

1991-01-01

440

Ultimately short ballistic vertical graphene Josephson junctions.  

PubMed

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale. PMID:25635386

Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

2015-01-01