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1

Formation and characterizations of ultra-shallow p +-n junctions using B 10H 14 ion implantation  

NASA Astrophysics Data System (ADS)

We report on the ultra-shallow p +-n junction formation by decaborane (B 10H 14) ion implantation into n-Si(1 0 0) substrates. The implantation energies of 5, 10 and 15 keV were used with the doses of 1 × 10 12 and 1 × 10 13 cm -2. The implanted samples were then subject to activation-annealing at 800, 900 and 1000 °C for 10 s. According to the results of secondary ion mass spectrometry, the p + layer thinner than 50 nm formed in most of the samples. Current-voltage ( I- V) measurements performed on the p +-n junction exhibited that the minimum leakage current density at -5 V was ˜10 -6 A/cm 2 when the decaborane of 1 × 10 13 cm -2 was implanted, while the maximum activated carrier dose of p + layers was measured up to 8.1 × 10 13 cm -2 by Hall measurements.

Jeon, G. Y.; Kim, J. S.; Whang, C. N.; Im, S.; Song, J.-H.; Song, J. H.; Choi, W. K.; Kim, H. K.

2003-05-01

2

Ultra-Shallow P{sup +}/N Junction Formation in Si Using Low Temperature Solid Phase Epitaxy Assisted with Laser Activation  

SciTech Connect

A combination of Ge pre-amorphization implantation (Ge-PAI), low-energy B implantation and laser annealing is a promising method to form highly-activated, abrupt and ultra-shallow junctions (USJ). In our previous report of IIT 2006, we succeeded in forming pn junctions less than 10 nm using non-melt double-pulsed green laser. However, a large leakage current under reverse bias was observed consequently due to residual defects in the implanted layer. In this study, a method to form USJ is proposed: a combination of low-temperature solid phase epitaxy and non-melt laser irradiation for B activation. Ge pre-amorphization implantation was performed at energy of 6 keV with a dose of 3x10{sup 14}/cm{sup 2}. Then B implantation was performed at energy of 0.2 keV with a dose of 1.2x10{sup 15}/cm{sup 2}. Samples were annealed at 400 deg. C for 10 h in nitrogen atmosphere. Subsequently, non-melt laser irradiation was performed at energy of 690 mJ/cm{sup 2} and pulse duration of 100 ns with intervals of 300 ns. As a result, USJ around 10 nm with better crystallinity was successfully formed. And the leakage current of pn diodes was reduced significantly. Moreover, it is proven from secondary ion mass spectroscopy (SIMS) analysis that transient enhanced diffusion (TED) of B is specifically suppressed.

Hara, Shuhei; Tanaka, Yuki; Fukaya, Takumi; Matsumoto, Satoru [Keio University, 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama, Kanagawa, 223-8522 (Japan); Suzuki, Toshiharu; Fuse, Genshu [SEN Corporation, an SHI and Axcelis Company, SBS Tower 9F, 4-10-1 Yoga, Setagaya-ku, Tokyo, 158-0097 (Japan); Kudo, Toshio; Sakuragi, Susumu [Sumitomo Heavy Industries Ltd., 19 Natsushima-cho, Yokosuka, Kanagawa, 237-8555 (Japan)

2008-11-03

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

Studies of ultra shallow n +–p junctions formed by low-energy As-implantation  

Microsoft Academic Search

The generation and the evolution of extended defects in ultra-shallow n+–p junctions, formed by As ion implantation into silicon at low energies of 15, 10 and 5keV and a dose of 1 × 1015cm?2, and rapid thermal annealing (RTA) at temperatures of 650°C ?T ? 950°C have been studied using transmission electron microscopy (TEM) measurements. The generated defects in the

D. Girginoudi; N. Georgoulas; A. Thanailakis; E. K. Polychroniadis

2004-01-01

5

Ultra-shallow P + \\/N junctions formed by recoil implantation  

Microsoft Academic Search

The concept of recoil implantation is proposed to facilitate fabrication of ultrashallow p+\\/n junctions. In this method, a thin boron film is first deposited onto the Si wafer surface. Then the boron atoms are knocked\\u000a into the Si substrate by Ge implantation or Ar plasma source ion implantation. Dopant activation and damage removal are achieved\\u000a via rapid thermal annealing. Preliminary

Henley L. Liu; Steven S. Gearhart; John H. Booske; Wei Wang

1998-01-01

6

Dopant Activation and Defect Analysis of Ultra-Shallow Junctions Made by Gas Cluster Ion Beams  

SciTech Connect

A long-standing problem in the fabrication of junctions by ion implantation is the enhanced diffusion caused by interstitial agglomeration and dissolution on annealing. Another side effect is residual damage that leads to junction leakage. The gas cluster ion beam technique (GCIB) offers a means of introducing dopant atoms without the creation of interstitials due to the low energy non-ballistic nature of the individual atoms and the localized thermal spike associated with the collision event between the large cluster and the silicon surface. We have employed cluster ion beams to infuse B into Si substrates to fabricate ultra-shallow junctions. Various annealing techniques were used to investigate GCIB B activation. We find that annealing at temperatures around 950 deg. C results in profiles that do not exhibit the extended tail characteristic of enhanced diffusion. This is in contrast to profiles in ion implanted samples, which inevitably result in enhanced diffusion. For laser and flash anneal, because the time scale of process is short, multiple anneal passes are needed in order to achieve low sheet resistance with little diffusion. We have shown that control of interfacial and surface smoothness is critical in improving junction characteristics.

Shao Yan; Hautala, John [TEL Epion, 37 Manning Rd., Billerica, MA 01821 (United States); Larson, Larry [FEP Division, SEMATECH, 2706 Montopolis Drive, Austin TX 78741 (United States); Jain, Amitabh [External Development and Manufacturing, Texas Instruments, 13121 TI Boulevard, MS 365 Dallas, TX 75243 (United States)

2008-11-03

7

A new plasma-aided solid-source implantation method for ultra-shallow p{sup +}/n junction fabrication  

SciTech Connect

Ultra-shallow p{sup +}/n junctions have been fabricated for the application of sub-micron CMOS source/drain formation using a new plasma-aided solid-source implantation method. In this method, very thin film ({approximately} 0.7 nm thick) of boron is first sputter deposited on the surface of the silicon wafer from a solid-form boron target. The wafer is then immersed in Air plasma and biased with a series of negative voltage pulses in a Plasma Source Ion Implantation (PSII) chamber. The argon ions are extracted from the plasma sheath and are accelerated so that they bombard the wafer surface. This drives boron into the Si substrate by means of ion beam mixing. This results in a very shallow boron-doped layer. Dopant activation and damage removal are achieved via short-cycle rapid thermal annealing (RTA). The boron profiles are measured by Secondary Ion Mass Spectroscopy (SIMS). Recent results show that a 0.7-nm thick boron layer implanted with 3-keV argon at a dose of 4 {times} 10{sup 15} cm{sup {minus}2} and annealed at 950 C for 10 seconds show a peak boron concentration of 3 {times} 10{sup 20} cm{sup {minus}3}, and the concentration is more than two orders of magnitude lower at a depth of 20 nm.

Liu, H.; Gearhart, S.S.; Booske, J.H. [Univ. of Wisconsin, Madison, WI (United States). Engineering Research Center for Plasma-Aided Manufacturing

1996-12-31

8

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

9

Material and electrical properties of ultra-shallow p+-n junctions formed by low-energy ion implantation and rapid thermal annealing  

Microsoft Academic Search

A study of low-energy ion implantation processes for the fabrication of ultrashallow p+-n junctions is presented. The resulting junctions are examined in terms of four key parameters: defect annihilation, junction depth, sheet resistance, and diode reverse leakage current. In the realm of very-low-energy ion implantation, Ge preamorphization is found to be largely ineffective at reducing junction depth, despite the fact

Shin Nam Hong; Gary A. Ruggles; Jimmie J. Wortman; M. C. Ozturk

1991-01-01

10

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

SciTech Connect

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

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

2012-12-15

11

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

12

Ultra-shallow seismic imaging of the top of the saturated zone  

NASA Astrophysics Data System (ADS)

We collected ultra-shallow seismic-reflection data to image the near-surface stratigraphy of a Kansas River point bar. We were successful in identifying a discontinuous clay layer and the top of the saturated zone at depths of 0.95 and 1.4 m. Seismic walkaway data collected using various .22-caliber ammunition show that decreased source energy is necessary to generate higher frequencies and prevent clipping of critical near-offset traces needed to identify ultra-shallow reflections. The seismic reflections exhibited average normal moveout velocities of 180-195 m/s with dominant frequencies of 200-450 Hz. Coincident subsurface features were also imaged using 200-MHz ground-penetrating radar. This study presents the shallowest seismic reflection from the top of the saturated zone reported in the literature to date and further demonstrates the potential of using seismic-reflection methods for ultra-shallow imaging of the subsurface as a stand-alone tool or in conjunction with other high-resolution geophysical techniques.

Sloan, Steven D.; Tsoflias, Georgios P.; Steeples, Don W.

2010-04-01

13

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

14

Gap junction expression is required for normal chemical synapse formation  

PubMed Central

Electrical and chemical synapses provide two distinct modes of direct communication between neurons, and the embryonic development of the two is typically not simultaneous. Instead, in both vertebrates and invertebrates, gap junction-based electrical synapses arise prior to chemical synaptogenesis, and the early circuits composed of gap junction-based electrical synapses resemble those produced later by chemical synapses. This developmental sequence from electrical to chemical synapses has led to the hypothesis that in developing neuronal circuits electrical junctions are necessary forerunners of chemical synapses. Up to now it has been difficult to test this hypothesis directly, but we can identify individual neurons in the leech nervous system from before the time when synapses are first forming, so we could test the hypothesis. Using RNA interference, we transiently reduced gap junction expression in individual identified neurons during the 2–4 days when chemical synapses normally form. We found that the expected chemical synapses failed to form on schedule, and they were still missing months later when the nervous system was fully mature. We conclude that the formation of gap junctions between leech neurons is a necessary step in the formation of chemical synaptic junctions, confirming the predicted relation between electrical synapses and chemical synaptogenesis. PMID:21068332

Todd, Krista L.; Kristan, William B.; French, Kathleen A.

2012-01-01

15

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

16

Shallow junction formation by polyatomic cluster ion implantation  

NASA Astrophysics Data System (ADS)

Recent integrated circuits require shallower junctions which are less than 0.1 ?m depth. Therefore, there is a strong demand for low energy ion beam techniques. Equivalent low-energy and high-current ion beams can be realized quite easily with cluster, because the kinetic energy of the cluster is shared between the constituent atoms. Additionally, cluster-ion beams avoid damage due to excessive charge. We have used polyatomic clusters, decaborane (B 10H 14), as a kind of B cluster, in order to form a very shallow {p +}/{n} junction. B SIMS profile of B 10H 14 implanted into Si (100) at 20 keV was quite similar to that of B implanted at 2 keV. These SIMS measurements revealed that the cluster ion beam can realize equivalent low-energy implantation quite easily. The implantation efficiency achieved was about 90%. The damage induced by B 10H 14 implantation was completely removed by a 600°C furnace anneal for 30 min, and implanted B atoms were electrically activated. After rapid thermal annealing (RTA) at 900°C of a sample prepared with a dose of 5 × 10 13 ions/cm 2, the sheet resistance decreased to about 600 ?/sq. and the activation efficiency was about 50%. These results show that a polyatomic cluster ion beam is useful for shallow junction formation.

Takeuchi, D.; Shimada, N.; Matsuo, J.; Yamada, I.

1997-01-01

17

Shallow junction formation by polyatomic cluster ion implantation  

SciTech Connect

Recent integrated circuits require shallow junctions which are less than 0.1 {mu}m depth. This creates a strong demand for low energy ion beam techniques. Equivalent low-energy and high-current ion beams can be realized quite easily with clusters, because the kinetic energy of the cluster is shared between the constituent atoms. Additionally, cluster-ion beams avoid damage due to excessive charge. We have used polyatomic clusters, decaborane (B{sub 10}H{sub 14}), as a kind of B cluster, in order to form a very shallow p{sup +} junction. A B SIMS profile of B{sub 10}H{sub 14} implanted into Si (100) at 20keV was quite similar to that of B implanted at 2keV. These SIMS measurements revealed that the cluster ion beam can realize equivalent low-energy implantation quite easily. The implantation efficiency achieved was about 90%. The damage induced by B{sub 10}H{sub 14} implantation was completely removed by a 600{degrees}C furnace anneal for 30 min, and implanted B atoms were electrically activated. After rapid thermal annealing (RTA) at 900{degrees}C of a sample prepared with a close of 5{times}10{sup 13} ion/cm{sup 2}, the sheet resistance decreased to about 600W/sq. and the activation efficiency was about 50%. These results show that a polyatomic cluster ion beam is useful for shallow junction formation.

Takeuchi, Daisuke; Shimada, Norihiro; Matsuo, Jiro; Yamada, Isao [Kyoto Univ., Sakyo (Japan)

1996-12-31

18

Wnt4 Participates in the Formation of Vertebrate Neuromuscular Junction  

PubMed Central

Neuromuscular junction (NMJ) formation requires the highly coordinated communication of several reciprocal signaling processes between motoneurons and their muscle targets. Identification of the early, spatially restricted cues in target recognition at the NMJ is still poorly documented, especially in mammals. Wnt signaling is one of the key pathways regulating synaptic connectivity. Here, we report that Wnt4 contributes to the formation of vertebrate NMJ in vivo. Results from a microarray screen and quantitative RT-PCR demonstrate that Wnt4 expression is regulated during muscle cell differentiation in vitro and muscle development in vivo, being highly expressed when the first synaptic contacts are formed and subsequently downregulated. Analysis of the mouse Wnt4?/? NMJ phenotype reveals profound innervation defects including motor axons overgrowing and bypassing AChR aggregates with 30% of AChR clusters being unapposed by nerve terminals. In addition, loss of Wnt4 function results in a 35% decrease of the number of prepatterned AChR clusters while Wnt4 overexpression in cultured myotubes increases the number of AChR clusters demonstrating that Wnt4 directly affects postsynaptic differentiation. In contrast, muscle structure and the localization of several synaptic proteins including acetylcholinesterase, MuSK and rapsyn are not perturbed in the Wnt4 mutant. Finally, we identify MuSK as a Wnt4 receptor. Wnt4 not only interacts with MuSK ectodomain but also mediates MuSK activation. Taken together our data reveal a new role for Wnt4 in mammalian NMJ formation that could be mediated by MuSK, a key receptor in synaptogenesis. PMID:22253844

Strochlic, Laure; Falk, Julien; Goillot, Evelyne; Sigoillot, Séverine; Bourgeois, Francine; Delers, Perrine; Rouvière, Jérôme; Swain, Amanda; Castellani, Valérie; Schaeffer, Laurent; Legay, Claire

2012-01-01

19

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

20

Advantageous Decaborane Ion Implantation for Ultra-shallow Junction of PMOSFETs Compared with Boron Monomer Implantation into Germanium Preamorphized Layer  

Microsoft Academic Search

We report the advantage of the decaborane (B10Hx +) ion implantation for sub-40-nm-gate-length PMOSFETs compared with conventional boron monomer ion implantation into pre-amorphized layer. PMOSFETs with decaborane ion implantation have a 5% higher on-current than those with boron monomer into pre-amorphized layer. In addition, the threshold voltage fluctuation of the PMOSFETs is also smaller. This high performance of the PMOSFETs

Takayuki Aoyama; S. Umisedo; N. Hamamoto; T. Nagayama; M. Tanjyo

2006-01-01

21

SOS1 and Ras regulate epithelial tight junction formation in the human airway through EMP1.  

PubMed

The human airway is lined with respiratory epithelial cells, which create a critical barrier through the formation of apical tight junctions. To investigate the molecular mechanisms underlying this process, an RNAi screen for guanine nucleotide exchange factors (GEFs) was performed in human bronchial epithelial cells (16HBE). We report that SOS1, acting through the Ras/MEK/ERK pathway, is essential for tight junction formation. Global microarray analysis identifies epithelial membrane protein 1 (EMP1), an integral tetraspan membrane protein, as a major transcriptional target. EMP1 is indispensable for tight junction formation and function in 16HBE cells and in a human airway basal progenitor-like cell line (BCi-NS1.1). Furthermore, EMP1 is significantly downregulated in human lung cancers. Together, these data identify important roles for SOS1/Ras and EMP1 in tight junction assembly during airway morphogenesis. PMID:25394671

Durgan, Joanne; Tao, Guangbo; Walters, Matthew S; Florey, Oliver; Schmidt, Anja; Arbelaez, Vanessa; Rosen, Neal; Crystal, Ronald G; Hall, Alan

2015-01-01

22

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); Olaf Bossinger (Heinrich-Heine Universität Düsseldorf;Institut für Genetik)

2002-12-06

23

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

24

Application of laser annealing to solar cell junction formation  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

25

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

26

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

27

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

Microsoft Academic Search

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

Amit Gupta; Ranganathan Kumar

2010-01-01

28

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

PubMed Central

Intercellullar junctions formed by cadherins, including desmosomes and adherens junctions, comprise two dimensional arrays of “trans” dimers formed between monomers emanating from opposing cell surfaces. Lateral “cis” interfaces between cadherins from the same cell surface have been proposed to play a role in cadherin clustering. Although the molecular details of cis interactions remain uncertain, they must define an anisotropic arrangement where binding is favorable only in certain orientations. Here we report Monte Carlo simulations performed on a 2D lattice constructed to account for the anisotropy in cadherin cis interactions. A crucial finding is that the “phase transition” between freely diffusing cadherin monomers and dimers and a condensed ordered 2D junction formed by dimers alone is a cooperative process involving both trans and cis interactions. Moreover, cis interactions, despite being too weak to be measured in solution, are critical to the formation of an ordered junction structure. We discuss these results in light of available experimental information on cadherin binding free energies that are transformed from their bulk solution values to interaction energies on a 2D lattice. PMID:20876147

Wu, Yinghao; Jin, Xiangshu; Harrison, Oliver; Shapiro, Lawrence; Honig, Barry H.; Ben-Shaul, Avinoam

2010-01-01

29

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

30

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

31

Effects of Intercellular Junction Protein Expression on Intracellular Ice Formation in Mouse Insulinoma Cells  

PubMed Central

The development of cryopreservation procedures for tissues has proven to be difficult in part because cells within tissue are more susceptible to intracellular ice formation (IIF) than are isolated cells. In particular, previous studies suggest that cell-cell interactions increase the likelihood of IIF by enabling propagation of ice between neighboring cells, a process thought to be mediated by gap junction channels. In this study, we investigated the effects of cell-cell interactions on IIF using three genetically modified strains of the mouse insulinoma cell line MIN6, each of which expressed key intercellular junction proteins (connexin-36, E-cadherin, and occludin) at different levels. High-speed video cryomicroscopy was used to visualize the freezing process in pairs of adherent cells, revealing that the initial IIF event in a given cell pair was correlated with a hitherto unrecognized precursor phenomenon: penetration of extracellular ice into paracellular spaces at the cell-cell interface. Such paracellular ice penetration occurred in the majority of cell pairs observed, and typically preceded and colocalized with the IIF initiation events. Paracellular ice penetration was generally not observed at temperatures >?5.65°C, which is consistent with a penetration mechanism via defects in tight-junction barriers at the cell-cell interface. Although the maximum temperature of paracellular penetration was similar for all four cell strains, genetically modified cells exhibited a significantly higher frequency of ice penetration and a higher mean IIF temperature than did wild-type cells. A four-state Markov chain model was used to quantify the rate constants of the paracellular ice penetration process, the penetration-associated IIF initiation process, and the intercellular ice propagation process. In the initial stages of freezing (>?15°C), junction protein expression appeared to only have a modest effect on the kinetics of propagative IIF, and even cell strains lacking the gap junction protein connexin-36 exhibited nonnegligible ice propagation rates. PMID:24209845

Higgins, Adam Z.; Karlsson, Jens O.M.

2013-01-01

32

Formation of Shallow n+-p Junction in Silicon by Spin-on Technique  

NASA Astrophysics Data System (ADS)

A simple mixture based on tetraethoxysilane was used to form shallow and highly phosphorus-doped n+ layers by the spin-on technique. Simultaneous doping with Yb was also used to improve the characteristics of the structures. The n+-p junctions obtained were investigated using optical methods, electron microscopy and Auger spectroscopy. Additionally, recombination in surfaces prepared under different conditions was monitored by a transient microwave absorption technique. It was found that the depth of the junction is about 0.4?m and the phosphorus concentration at the surface reaches 2 · 1020cm-3. Adding Yb to the spinning solution and the highly doped surface coating by porous silicon layer formation both reduce the surface recombination. The lowest obtained value of the surface recombination velocity was close to 170cm/s.

Grigoras, K.; Pa?ebutas, V.; Sabataityt?, J.; Šimkien?, I.; Tvardauskas, H.; Gaubas, E.; Härkönen, J.

33

Effect of chloroquine on the formation of tight junctions in cultured immature rat Sertoli cells.  

PubMed

Adjoining immature Sertoli cells in the seminiferous epithelium form a tight junctional complex leading to the development of the blood-testis barrier. Protease and antiprotease activities have been implicated in the process of formation of tight junctions. Here, we report the effect of chloroquine, an antimalarial drug with antiprotease activity, on the development of intercellular tight junctions in cultured immature rat Sertoli cells. For positive control, the classical lysosomotropic agent ammonium chloride was used. Sertoli cells were seeded in serum-free defined medium at a density of 3 x 10(6) cells/0.64-cm2 well on Matrigel-covered Millicell-HA filters. Chloroquine at concentrations ranging from 25 to 100 microM was added to the outer chamber of the bicameral system on either day 1 or 7 of the culture. The formation of the tight junction was monitored by the measurement of the transepithelial resistance (TER) at 24-hour intervals using an impedance meter. TER in untreated controls was 50 ohms/cm2 on day 1; it increased progressively to 80 ohms/cm2 by day 7 and plateaued until day 12. The cells treated from day 1 with chloroquine also showed a dose-dependent progressive increase in TER until day 9, reaching 225 ohms/cm2 in cells treated with the 100 microM concentration. In comparison to controls, the increase in TER was significantly higher. In cells treated with chloroquine starting from day 7 of culture onwards, there was no observable difference in TER from the untreated control. These observations demonstrate that chloroquine and ammonium chloride increase the TER of immature Sertoli cells in the bicameral chamber. PMID:8792215

Okanlawon, A; Dym, M

1996-01-01

34

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

35

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

36

Laser annealing of ion implanted CZ silicon for solar cell junction formation  

NASA Technical Reports Server (NTRS)

The merits of large spot size pulsed laser annealing of phosphorus implanted, Czochralski grown silicon for function formation of solar cells are evaluated. The feasibility and requirements are also determined to scale-up a laser system to anneal 7.62 cm diameter wafers at a rate of one wafer/second. Results show that laser annealing yields active, defect-free, shallow junction devices. Functional cells with AM 1 conversion efficiencies up to 15.4% for 2 x 2 cm and 2 x 4 cm sizes were attained. For larger cells, 7.62 cm dia., conversion efficiencies ranged up to 14.5%. Experiments showed that texture etched surfaces are not compatible with pulsed laser annealing due to the surface melting caused by the laser energy. When compared with furnace annealed cells, the laser annealed cells generally exhibited conversion efficiencies which were equal to or better than those furnace annealed. In addition, laser annealing has greater throughput potential.

Katzeff, J. S.

1981-01-01

37

Tetraspanin Protein CD9 Is a Novel Paranodal Component Regulating Paranodal Junctional Formation  

Microsoft Academic Search

The axoglial paranodal junction is essential for the proper localization of ion channels around the node of Ranvier. The integrity of this junction is important for nerve conduction. Although recent studies have made significant progress in understanding the molecular composition of the paranodal junction, it is not known how these membrane components are distributed to the appropriate sites and interact

Tomoko Ishibashi; Lei Ding; Kazuhiro Ikenaka; Yoshiro Inoue; Kenji Miyado; Eisuke Mekada; Hiroko Baba

2004-01-01

38

Dexamethasone disrupts intercellular junction formation and cytoskeleton organization in human trabecular meshwork cells  

PubMed Central

Purpose Patients reproduce symptoms of primary open-angle glaucoma (POAG) when treated with glucocorticoids (GCs) topically on the eyes. Here we investigated the effects of GCs on junctional protein expression and cytoskeleton organization in primary human trabecular meshwork (TM) cultures to understand the molecular pathologies of POAG. Methods Human TM cells from POAG (GTM) and age-matched nondiseased (NTM) individuals were obtained by standard surgical trabeculectomy. Some of the cultures were treated with dexamethasone (DEX), a synthetic GC, at 1–5×10?7 mol/l for 1–7 days. The expression levels of zonula occluden-1 (ZO-1) and connexin43 (Cx43) in TM cells with or without DEX treatment were measured using reverse transcription (RT)–PCR, immunocytochemistry, and western blot analysis. Results mRNA and proteins of ZO-1 and Cx43 were found in both NTM and GTM cells. ZO-1 and Cx43 were located on the plasma membrane, especially along the border of adjacent cells. ZO-1 had no marked changes in localization in NTM and GTM cells after treatment with 10?7 mol/l DEX for 48 h, whereas Cx43 appeared to increase in the cytoplasm. mRNA of two ZO-1 isoforms, ?+ and ?–, were present in TM cells, and the former was expressed less than the latter. Only ZO-1 ?– isoform protein was expressed in NTM cells, whereas proteins of both isoforms were found in GTM cells. DEX increased the protein levels of ZO-1 and Cx43 in both NTM and GTM cells. DEX also altered the F-actin architecture and promoted cross-linked actin network formation, the effects of which were more pronounced in GTM cells. Conclusions Our findings not only provide molecular insights to the pathogenesis of GC-induced glaucoma but also suggest that junctional proteins ZO-1 and Cx43 as well as F-actin are targets for developing new modalities in glaucoma therapy. PMID:20090922

Zhuo, Ye Hong; He, Yuan; Leung, Kar Wah; Hou, Fei; Li, Yi Qing; Chai, Fang

2010-01-01

39

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

40

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

41

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

42

aPKC phosphorylates JAM-A at Ser285 to promote cell contact maturation and tight junction formation  

PubMed Central

The PAR-3–atypical protein kinase C (aPKC)–PAR-6 complex has been implicated in the development of apicobasal polarity and the formation of tight junctions (TJs) in vertebrate epithelial cells. It is recruited by junctional adhesion molecule A (JAM-A) to primordial junctions where aPKC is activated by Rho family small guanosine triphosphatases. In this paper, we show that aPKC can interact directly with JAM-A in a PAR-3–independent manner. Upon recruitment to primordial junctions, aPKC phosphorylates JAM-A at S285 to promote the maturation of immature cell–cell contacts. In fully polarized cells, S285-phosphorylated JAM-A is localized exclusively at the TJs, and S285 phosphorylation of JAM-A is required for the development of a functional epithelial barrier. Protein phosphatase 2A dephosphorylates JAM-A at S285, suggesting that it antagonizes the activity of aPKC. Expression of nonphosphorylatable JAM-A/S285A interferes with single lumen specification during cyst development in three-dimensional culture. Our data suggest that aPKC phosphorylates JAM-A at S285 to regulate cell–cell contact maturation, TJ formation, and single lumen specification. PMID:22371556

Iden, Sandra; Misselwitz, Steve; Peddibhotla, Swetha S.D.; Tuncay, Hüseyin; Rehder, Daniela; Gerke, Volker; Robenek, Horst; Suzuki, Atsushi

2012-01-01

43

Gap junction proteins exhibit early and specific expression during intramembranous bone formation in the developing chick mandible  

Microsoft Academic Search

The spatial and temporal expression of three closely related members of the connexin family of gap junction proteins (connexin42, Cx42; connexin43, Cx43; and connexin45, Cx45) was evaluated during bone formation in the mandibular process of the chick embryo. Mandibles of chick embryos from Hamburger and Hamilton stage 25 (approximately 5 days) through 19 days of development were dissected, serially sectioned

R. Minkoff; V. R. Rundus; S. B. Parker; E. L. Hertzberg; J. G. Laing; E. C. Beyer

1994-01-01

44

The transmembrane protein Macroglobulin complement-related is essential for septate junction formation and epithelial barrier function in Drosophila.  

PubMed

Occluding cell-cell junctions in epithelia form physical barriers that separate different membrane domains, restrict paracellular diffusion and prevent pathogens from spreading across tissues. In invertebrates, these functions are provided by septate junctions (SJs), the functional equivalent of vertebrate tight junctions. How the diverse functions of SJs are integrated and modulated in a multiprotein complex is not clear, and many SJ components are still unknown. Here we report the identification of Macroglobulin complement-related (Mcr), a member of the conserved ?-2-macroglobulin (?2M) complement protein family, as a novel SJ-associated protein in Drosophila. Whereas ?2M complement proteins are generally known as secreted factors that bind to surfaces of pathogens and target them for phagocytic uptake, Mcr represents an unusual ?2M protein with a predicted transmembrane domain. We show that Mcr protein localizes to lateral membranes of epithelial cells, where its distribution overlaps with SJs. Several SJ components are required for the correct localization of Mcr. Conversely, Mcr is required in a cell-autonomous fashion for the correct membrane localization of SJ components, indicating that membrane-bound rather than secreted Mcr isoforms are involved in SJ formation. Finally, we show that loss of Mcr function leads to morphological, ultrastructural and epithelial barrier defects resembling mutants lacking SJ components. Our results, along with previous findings on the role of Mcr in phagocytosis, suggest that Mcr plays dual roles in epithelial barrier formation and innate immunity. Thus, Mcr represents a novel paradigm for investigating functional links between occluding junction formation and pathogen defense mechanisms. PMID:24496626

Bätz, Tilmann; Förster, Dominique; Luschnig, Stefan

2014-02-01

45

Integration of Stem Cells into the Cardiac Syncytium: Formation of Gap Junctions  

Microsoft Academic Search

\\u000a The heart is a functional syncytium. This means that each myocyte is electrically connected to other myocytes in its vicinity.\\u000a Functional electrical coupling requires gap junctions. Gap junctions are composed of connexins. There are over 20 connexins\\u000a in the human genome. If either electrical or mechanical regeneration of cardiac function is to be achieved via cell therapy\\u000a (exclusive of paracrine

Peter R. Brink; Ira S. Cohen; Richard T. Mathias

46

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

47

Formation of electronic junctions on molecularly modified surfaces by lift-and-float electrical contacts.  

PubMed

Here, we report a simple method of forming electrical contacts on soft surfaces of organic monolayers and organically capped nanoparticles. It is based on the lift of predefined contacts of silver paste on a water surface and their pickup and float on a soft surface by capillary force. Three different surfaces of silicon--hydrogen terminated, covalently bonded organic molecules, and a thin film of organically capped CdSe nanoparticles--were used to constitute electronic junctions by lift and float of individual contacts. Charge transport measurements clearly demonstrate that these junctions are free from shorting and wrinkling of the top contact and damage of molecular films. Hence, the method is simple, effective, nondestructive, and economical to form electronic junctions on molecular surfaces. PMID:19437791

Ikram, I Mohamed; Rabinal, M K; Kalasad, M N; Mulimani, B G

2009-03-01

48

Formation of p-n-p junction with ionic liquid gate in graphene  

SciTech Connect

Ionic liquid gating is a technique which is much more efficient than solid gating to tune carrier density. To observe the electronic properties of such a highly doped graphene device, a top gate made of ionic liquid has been used. By sweeping both the top and back gate voltage, a p-n-p junction has been created. The mechanism of forming the p-n-p junction has been discussed. Tuning the carrier density by ionic liquid gate can be an efficient method to be used in flexible electronics.

He, Xin; Tang, Ning, E-mail: ntang@pku.edu.cn, E-mail: geweikun@mail.tsinghua.edu.cn, E-mail: bshen@pku.edu.cn; Duan, Junxi; Zhang, Yuewei; Lu, Fangchao; Xu, Fujun; Yang, Xuelin [State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871 (China); Gao, Li [Institute of Life Sciences, Jiangsu University, Zhenjiang 212013, Jiangsu Province (China); Wang, Xinqiang; Shen, Bo, E-mail: ntang@pku.edu.cn, E-mail: geweikun@mail.tsinghua.edu.cn, E-mail: bshen@pku.edu.cn [State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China); Ge, Weikun, E-mail: ntang@pku.edu.cn, E-mail: geweikun@mail.tsinghua.edu.cn, E-mail: bshen@pku.edu.cn [Department of Physics, Tsinghua University, Beijing 100084 (China)

2014-04-07

49

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

50

Droplet formation in microfluidic T-junction generators operating in the transitional regime. III. Dynamic surfactant effects  

NASA Astrophysics Data System (ADS)

This study extends our previous work on droplet generation in microfluidic T-junction generators to include dynamic interfacial tension effects created by the presence of surfactants. In Paper I [T. Glawdel, C. Elbuken, and C. L. Ren, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.016322 85, 016322 (2012)], we presented experimental findings regarding the formation process in the squeezing-to-transition regime, and in Paper II [T. Glawdel, C. Elbuken, and C. L. Ren, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.016323 85, 016323 (2012)] we developed a theoretical model that describes the performance of T-junction generators without surfactants. Here we study dynamic interfacial tension effects for two surfactants, one with a small molecular weight that adsorbs quickly, and the other with a large molecular weight that adsorbs slowly. Using the force balance developed in Paper II we extract the dynamic interfacial tension from high speed videos obtained during experiments. We then develop a theoretical model to predict the dynamic interfacial tension in microfluidic T-junction generators as a function of the surfactant properties, flow conditions, and generator design. This model is then incorporated into the overall model for generator performance to effectively predict the size of droplets produced when surfactants are present.

Glawdel, Tomasz; Ren, Carolyn L.

2012-08-01

51

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

52

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

PubMed Central

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

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

2012-01-01

53

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

PubMed

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

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

2014-11-12

54

Magnetic oxide formation at Al2O3/Co84Fe16 interface in magnetic tunnel junction  

NASA Astrophysics Data System (ADS)

We investigated the interfacial status of ferromagnetic Co84Fe16/insulating barrier Al2O3 of the Al2O3-based magnetic tunnel junction (MTJ) using various x-ray scattering measurements. The results show formation of orthorhombic AlFeO3 magnetic nanoparticles at the interface, which are embedded in the Al2O3 cage. Their thickness and planner size vary with the plasma oxidation time. We also observed an interesting magnetic anomaly with a minimum magnetic coercivity near the AlFeO3 ferrimagnetic TC, which is successfully explained in terms of the AlFeO3 nanoparticles and nanoscale CoFe grains with size distribution.

Rho, K.-J.; Lee, J.-S.; Lee, K.-B.; Park, J.-H.; Kim, J.-Y.; Park, Y. J.; Kim, K. J.; Joo, S. J.; Rhie, K.

2011-05-01

55

Formation of axial metal-semiconductor junctions in GaAs nanowires by thermal annealing  

NASA Astrophysics Data System (ADS)

We demonstrate the formation of nanoscale axial Schottky contacts in GaAs nanowires by thermal annealing of NiGeAu multilayers. Energy dispersive x-ray spectroscopy indicates that in specific annealing conditions a sharply-defined Au-rich phase can be obtained in the vicinity of the metallic contacts. Charge transport characteristics are analyzed for different degrees of diffusion of the Au-rich phase in the wire and indicate that it has a metallic nature. The mechanism behind this local post-growth modification of the nanowire composition and its potential impact on device applications are discussed.

Orrù, Marta; Rubini, Silvia; Roddaro, Stefano

2014-05-01

56

Neuromuscular junction formation between human stem cell-derived motoneurons and human skeletal muscle in a defined system.  

PubMed

Functional in vitro models composed of human cells will constitute an important platform in the next generation of system biology and drug discovery. This study reports a novel human-based in vitro Neuromuscular Junction (NMJ) system developed in a defined serum-free medium and on a patternable non-biological surface. The motoneurons and skeletal muscles were derived from fetal spinal stem cells and skeletal muscle stem cells. The motoneurons and skeletal myotubes were completely differentiated in the co-culture based on morphological analysis and electrophysiology. NMJ formation was demonstrated by phase contrast microscopy, immunocytochemistry and the observation of motoneuron-induced muscle contractions utilizing time-lapse recordings and their subsequent quenching by d-Tubocurarine. Generally, functional human based systems would eliminate the issue of species variability during the drug development process and its derivation from stem cells bypasses the restrictions inherent with utilization of primary human tissue. This defined human-based NMJ system is one of the first steps in creating functional in vitro systems and will play an important role in understanding NMJ development, in developing high information content drug screens and as test beds in preclinical studies for spinal or muscular diseases/injuries such as muscular dystrophy, Amyotrophic lateral sclerosis and spinal cord repair. PMID:21944471

Guo, Xiufang; Gonzalez, Mercedes; Stancescu, Maria; Vandenburgh, Herman H; Hickman, James J

2011-12-01

57

Rab3Gap1 mediates exocytosis of Claudin-1 and tight junction formation during epidermal barrier acquisition  

PubMed Central

Epidermal barrier acquisition during late murine gestation is accompanied by an increase in Akt kinase activity and cJun dephosphorlyation. The latter is directed by the Ppp2r2a regulatory subunit of the Pp2a phosphatase. This was accompanied by a change of Claudin-1 localisation to the cell surface and interaction between Occludin and Claudin-1 which are thought to be required for tight junction formation. The aim of this study was to determine the nature of the barrier defect caused by the loss of AKT/Ppp2r2a function. There was a paracellular barrier defect in rat epidermal keratinocytes expressing a Ppp2r2a siRNA. In Ppp2r2a knockdown cells, Claudin-1 was located to the cytoplasm and its expression was increased. Inhibiting cJun phosphorylation restored barrier function and plasma membrane localisation of Claudin-1. Expression of the Rab3 GTPase activating protein, Rab3Gap1, was restored in Ppp2r2a siRNA cells when cJun phosphorylation was inhibited. During normal mouse epidermal development, Claudin-1 plasma membrane localisation and Rab3Gap1 cell surface expression were co-incident with Akt activation in mouse epidermis, strongly suggesting a role of Rab3Gap1 in epidermal barrier acquisition. Supporting this hypothesis, siRNA knockdown of Rab3Gap1 prevented plasma membrane Claudin-1 expression and the formation of a barrier competent epithelium. Replacing Rab3Gap1 in Ppp2r2a knockdown cells was sufficient to rescue Claudin-1 transport to the cell surface. Therefore these data suggest Rab3Gap1 mediated exocytosis of Claudin-1 is an important component of epidermal barrier acquisition during epidermal development. PMID:23685254

Youssef, G.; Gerner, L.; Naeem, A.S.; Ralph, O.; Ono, M.; O’Neill, C.A.; O’Shaughnessy, R.F.L.

2013-01-01

58

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

PubMed

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

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

2014-08-01

59

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

60

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

61

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

62

Doped semiconductor nanocrystal junctions  

NASA Astrophysics Data System (ADS)

Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (ND?1020-1021cm-3) silicon nanocrystals (NCs) in the 2-50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as ND-1/3, and depleted charge linearly increasing with the NC diameter and varying as ND1/3. We thus establish a "nanocrystal counterpart" of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

Borowik, ?.; Nguyen-Tran, T.; Roca i Cabarrocas, P.; Mélin, T.

2013-11-01

63

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

Microsoft Academic Search

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

Allison M Fannon; David R Colman

1996-01-01

64

Characterization of DNA end joining in a mammalian cell nuclear extract: junction formation is accompanied by nucleotide loss, which is limited and uniform but not site specific.  

PubMed Central

Mammalian cells have a marked capacity to repair double-strand breaks in DNA, but the molecular and biochemical mechanisms underlying this process are largely unknown. A previous report has described an activity from mammalian cell nuclei that is capable of multimerizing blunt-ended DNA substrates (R. Fishel, M.K. Derbyshire, S.P. Moore, and C.S.H. Young, Biochimie 73:257-267, 1991). In this report, we show that nuclear extracts from HeLa cells contain activities which preferentially join linear plasmid substrates in either a head-to-head or tail-to-tail configuration, that the joining reaction is covalent, and that the joining is accompanied by loss of sequence at the junction. Sequencing revealed that there was a loss of a uniform number of nucleotides from junctions formed from any one type of substrate. The loss was not determined by any simple site-specific mechanism, but the number of nucleotides lost was affected by the precise terminal sequence. There was no major effect on the efficiency or outcome of the joining reaction with substrates containing blunt ends or 3' or 5' protruding ends. Using a pair of plasmid molecules with distinguishable restriction enzyme sites, we also observed that blunt-ended DNA substrates could join with those containing protruding 3' ends. As with the junctions formed between molecules with identical ends, there was uniform loss of nucleotides. Taken together, the data are consistent with two models for the joining reaction in which molecules are aligned either throughout most of their length or by using small sequence homologies located toward their ends. Although either model can explain the preferential formation of head-to-head and tail-to-tail products, the latter predicts the precise lossof nucleotides observed. These activities are found in all cell lines examined so far and most likely represent an important repair activity of the mammalian cell. Images PMID:8264584

Nicolás, A L; Young, C S

1994-01-01

65

Numerical modeling and experimental investigation of gas–liquid slug formation in a microchannel T-junction  

Microsoft Academic Search

Gas–liquid two-phase flow in a microfluidic T-junction with nearly square microchannels of 113?m hydraulic diameter was investigated experimentally and numerically. Air and water superficial velocities were 0.018–0.791m\\/s and 0.042–0.757m\\/s, respectively. Three-dimensional modeling was performed with computational fluid dynamics (CFD) software FLUENT and the volume of fluid (VOF) model. Slug flow (snapping\\/breaking\\/jetting) and stratified flow were observed experimentally. Numerically predicted void

Rafael M. Santos; Masahiro Kawaji

2010-01-01

66

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

67

The zinc sensing receptor, ZnR/GPR39, controls proliferation and differentiation of colonocytes and thereby tight junction formation in the colon.  

PubMed

The intestinal epithelium is a renewable tissue that requires precise balance between proliferation and differentiation, an essential process for the formation of a tightly sealed barrier. Zinc deficiency impairs the integrity of the intestinal epithelial barrier and is associated with ulcerative and diarrheal pathologies, but the mechanisms underlying the role of Zn(2+) are not well understood. Here, we determined a role of the colonocytic Zn(2+) sensing receptor, ZnR/GPR39, in mediating Zn(2+)-dependent signaling and regulating the proliferation and differentiation of colonocytes. Silencing of ZnR/GPR39 expression attenuated Zn(2+)-dependent activation of ERK1/2 and AKT as well as downstream activation of mTOR/p70S6K, pathways that are linked with proliferation. Consistently, ZnR/GPR39 silencing inhibited HT29 and Caco-2 colonocyte proliferation, while not inducing caspase-3 cleavage. Remarkably, in differentiating HT29 colonocytes, silencing of ZnR/GPR39 expression inhibited alkaline phosphatase activity, a marker of differentiation. Furthermore, Caco-2 colonocytes showed elevated expression of ZnR/GPR39 during differentiation, whereas silencing of ZnR/GPR39 decreased monolayer transepithelial electrical resistance, suggesting compromised barrier formation. Indeed, silencing of ZnR/GPR39 or chelation of Zn(2+) by the cell impermeable chelator CaEDTA was followed by impaired expression of the junctional proteins, that is, occludin, zonula-1 (ZO-1) and E-cadherin. Importantly, colon tissues of GPR39 knockout mice also showed a decrease in expression levels of ZO-1 and occludin compared with wildtype mice. Altogether, our results indicate that ZnR/GPR39 has a dual role in promoting proliferation of colonocytes and in controlling their differentiation. The latter is followed by ZnR/GPR39-dependent expression of tight junctional proteins, thereby leading to formation of a sealed intestinal epithelial barrier. Thus, ZnR/GPR39 may be a therapeutic target for promoting epithelial function and tight junction barrier integrity during ulcerative colon diseases. PMID:24967969

Cohen, L; Sekler, I; Hershfinkel, M

2014-01-01

68

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

69

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

70

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

71

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

PubMed

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

Fannon, A M; Colman, D R

1996-09-01

72

DNA models of trinucleotide frameshift deletions: the formation of loops and bulges at the primer-template junction.  

PubMed

Although mechanisms of single-nucleotide residue deletion have been investigated, processes involved in the loss of longer nucleotide sequences during DNA replication are poorly understood. Previous reports have shown that in vitro replication of a 3'-TGC TGC template sequence can result in the deletion of one 3'-TGC. We have used low-energy circular dichroism (CD) and fluorescence spectroscopy to investigate the conformations and stabilities of DNA models of the replication intermediates that may be implicated in this frameshift. Pyrrolocytosine or 2-aminopurine residues, site-specifically substituted for cytosine or adenine in the vicinity of extruded base sequences, were used as spectroscopic probes to examine local DNA conformations. An equilibrium mixture of four hybridization conformations was observed when template bases looped-out as a bulge, i.e. a structure flanked on both sides by duplex DNA. In contrast, a single-loop structure with an unusual unstacked DNA conformation at its downstream edge was observed when the extruded bases were positioned at the primer-template junction, showing that misalignments can be modified by neighboring DNA secondary structure. These results must be taken into account in considering the genetic and biochemical mechanisms of frameshift mutagenesis in polymerase-driven DNA replication. PMID:19155277

Baase, Walter A; Jose, Davis; Ponedel, Benjamin C; von Hippel, Peter H; Johnson, Neil P

2009-04-01

73

DNA models of trinucleotide frameshift deletions: the formation of loops and bulges at the primer–template junction  

PubMed Central

Although mechanisms of single-nucleotide residue deletion have been investigated, processes involved in the loss of longer nucleotide sequences during DNA replication are poorly understood. Previous reports have shown that in vitro replication of a 3?-TGC TGC template sequence can result in the deletion of one 3?-TGC. We have used low-energy circular dichroism (CD) and fluorescence spectroscopy to investigate the conformations and stabilities of DNA models of the replication intermediates that may be implicated in this frameshift. Pyrrolocytosine or 2-aminopurine residues, site-specifically substituted for cytosine or adenine in the vicinity of extruded base sequences, were used as spectroscopic probes to examine local DNA conformations. An equilibrium mixture of four hybridization conformations was observed when template bases looped-out as a bulge, i.e. a structure flanked on both sides by duplex DNA. In contrast, a single-loop structure with an unusual unstacked DNA conformation at its downstream edge was observed when the extruded bases were positioned at the primer–template junction, showing that misalignments can be modified by neighboring DNA secondary structure. These results must be taken into account in considering the genetic and biochemical mechanisms of frameshift mutagenesis in polymerase-driven DNA replication. PMID:19155277

Baase, Walter A.; Jose, Davis; Ponedel, Benjamin C.; von Hippel, Peter H.; Johnson, Neil P.

2009-01-01

74

Ultra low energy boron implantation using cluster ions for decananometer MOSFETs  

NASA Astrophysics Data System (ADS)

Two types of applications in ultra low-energy boron implantation with decaborane (B10H14) molecules for highly miniaturized devices are presented. One is the formation of a 7-nm-deep junction. This ultra shallow junction was applied to a pMOSFET with a gate length of around 50 nm. The other application of this technique is the formation of ultra shallow channels in buried-channel pMOSFETs. We successfully fabricated this type of device, achieving a low threshold voltage and a steep subthreshold.

Sugii, T.; Goto, K.; Tanaka, T.; Matsuo, J.; Yamada, I.

1999-06-01

75

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

76

A tectonically controlled alluvial fan which developed into a marine fan-delta at a complex triple junction: Miocene Gildirli Formation of the Adana Basin, Turkey  

NASA Astrophysics Data System (ADS)

The sediments of the Gildirli Formation in the Karaisali embayment of the Adana Basin, southern Turkey, records the evolution, under tectonic control at a complex triple junction, of an alluvial fan into a fan-delta during a rapid Early Miocene transgression. The alluvial fan is represented by the lower part of the formation (Çakmak Member) and is characterized by an internal architecture, recording an overall progradation of the coarse proximal fan conglomerates over distal fine-grained sediments. The conglomerates contain mostly Upper Cretaceous limestone clasts of various sizes derived from the faulted mountain front of the Taurus range where this limestone is widely exposed. This active mountain front delimited the Karaisah embayment to the north and provided, during the fault activity, abundant coarse clasts to this area throughout the deposition of both the alluvial fan and the overlying fan-delta sediments. The production of fine detritus during the faulting was very limited and therefore this source contributed little fine grain detritus to the sediments. Provenance studies indicate that the fine clastics in the Gildirli Formation were carried by streams during periods of active faulting and also during periods of tectonic quiescence from a far-distant source in the hinterlands of the Taurus Mountains. The recurrent activity along the northern boundary-fault resulted in the intercalation of these fine clastics with the predominant coarse sediments in this formation. When the study area was flooded from the south by a rapidly deepening Early Miocene sea, the accumulation of all these sediments took place in a fan-delta environment. The fan-delta sediments constitute the upper parts of the Gildirli Formation (Kabalaktepe Member) and display an inverse facies pattern in which foreset beds overlie topsets and hence an upward-fining and deepening sequence. This deviation from a genetic upward-coarsening sequence of a typical marine delta was perhaps the result of a rapid relative rise in sea-level, due to tectonically induced subsidence of the area possibly coupled with a short-term global sea-level rise in the Burdigalian.

Görür, Naci

1992-12-01

77

Arp2/3 promotes junction formation and maintenance in the Caenorhabditis elegans intestine by regulating membrane association of apical proteins.  

PubMed

It has been proposed that Arp2/3, which promotes nucleation of branched actin, is needed for epithelial junction initiation but is less important as junctions mature. We focus here on how Arp2/3 contributes to the Caenorhabditis elegans intestinal epithelium and find important roles for Arp2/3 in the maturation and maintenance of junctions in embryos and adults. Electron microscope studies show that embryos depleted of Arp2/3 form apical actin-rich microvilli and electron-dense apical junctions. However, whereas apical/basal polarity initiates, apical maturation is defective, including decreased apical F-actin enrichment, aberrant lumen morphology, and reduced accumulation of some apical junctional proteins, including DLG-1. Depletion of Arp2/3 in adult animals leads to similar intestinal defects. The DLG-1/AJM-1 apical junction proteins, and the ezrin-radixin-moesin homologue ERM-1, a protein that connects F-actin to membranes, are required along with Arp2/3 for apical F-actin enrichment in embryos, whereas cadherin junction proteins are not. Arp2/3 affects the subcellular distribution of DLG-1 and ERM-1. Loss of Arp2/3 shifts both ERM-1 and DLG-1 from pellet fractions to supernatant fractions, suggesting a role for Arp2/3 in the distribution of membrane-associated proteins. Thus, Arp2/3 is required as junctions mature to maintain apical proteins associated with the correct membranes. PMID:21697505

Bernadskaya, Yelena Y; Patel, Falshruti B; Hsu, Hsiao-Ting; Soto, Martha C

2011-08-15

78

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

79

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.

80

Inelastic electron tunnelling spectroscopy—IV. A study of the formation of formic acid from atmospheric carbon dioxide and water within an Al—Aloxide—Pb tunnelling junction  

NASA Astrophysics Data System (ADS)

Considerable confusion exists in the literature regarding the interpretation of peaks in the spectra of aluminium—aluminium oxide—lead tunnelling junctions doped with either water or water vapour. These peaks, which appear in the CH bend and stretch regions, have been variously assigned as trace organic impurities or as formic acid chemically produced within the tunnelling junction by a reaction between atmospheric carbon dioxide and the water dopant. The present work attempts to resolve this ambiguity by producing formic acid tunnelling spectra and comparing these with spectra produced from triply distilled water doped junctions. These spectra, which fingerprint exactly, have been assigned. Potential organic impurities in the water have been investigated by high resolution mass spectroscopy. The tunnelling spectrum of a junction electrode penetration doped with a suspension of calcium oxide in water has been produced and is assigned as calcium carbonate. It is suggested that a reaction takes place between calcium hydroxide and carbon dioxide adsorbed on the surface of the alumina to produce calcium carbonate. It is concluded that formic acid is produced within tunnelling junctions by a reaction between atmospheric carbon dioxide and water on the alumina surface.

Field, B. O.; Hart, R.; Lewis, D. M.

1985-01-01

81

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

82

Random telegraph signals in molecular junctions  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

83

Holographic Josephson Junctions  

SciTech Connect

We construct a gravitational dual of a Josephson junction. Calculations on the gravity side reproduce the standard relation between the current across the junction and the phase difference of the condensate. We also study the dependence of the maximum current on the temperature and size of the junction and reproduce familiar results.

Horowitz, Gary T.; Santos, Jorge E.; Way, Benson [Department of Physics, University of California, Santa Barbara, California 93106-4030 (United States)

2011-06-03

84

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

85

Junctional adhesion molecule a promotes epithelial tight junction assembly to augment lung barrier function.  

PubMed

Epithelial barrier function is maintained by tight junction proteins that control paracellular fluid flux. Among these proteins is junctional adhesion molecule A (JAM-A), an Ig fold transmembrane protein. To assess JAM-A function in the lung, we depleted JAM-A in primary alveolar epithelial cells using shRNA. In cultured cells, loss of JAM-A caused an approximately 30% decrease in transepithelial resistance, decreased expression of the tight junction scaffold protein zonula occludens 1, and disrupted junctional localization of the structural transmembrane protein claudin-18. Consistent with findings in other organs, loss of JAM-A decreased ?1 integrin expression and impaired filamentous actin formation. Using a model of mild systemic endoxotemia induced by i.p. injection of lipopolysaccharide, we report that JAM-A(-/-) mice showed increased susceptibility to pulmonary edema. On injury, the enhanced susceptibility of JAM-A(-/-) mice to edema correlated with increased, transient disruption of claudin-18, zonula occludens 1, and zonula occludens 2 localization to lung tight junctions in situ along with a delay in up-regulation of claudin-4. In contrast, wild-type mice showed no change in lung tight junction morphologic features in response to mild systemic endotoxemia. These findings support a key role of JAM-A in promoting tight junction homeostasis and lung barrier function by coordinating interactions among claudins, the tight junction scaffold, and the cytoskeleton. PMID:25438062

Mitchell, Leslie A; Ward, Christina; Kwon, Mike; Mitchell, Patrick O; Quintero, David A; Nusrat, Asma; Parkos, Charles A; Koval, Michael

2015-02-01

86

Can gap junctions deliver?  

PubMed

In vivo delivery of small interfering RNAs (siRNAs) to target cells via the extracellular space has been hampered by dilution effects and immune responses. Gap junction-mediated transfer between cells avoids the extracellular space and its associated limitations. Because of these advantages cell based delivery via gap junctions has emerged as a viable alternative for siRNA or miRNA delivery. Here we discuss the advantages and disadvantages of extracellular delivery and cell to cell delivery via gap junction channels composed of connexins. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics. PMID:21986484

Brink, Peter R; Valiunas, Virginijus; Gordon, Chris; Rosen, Michael R; Cohen, Ira S

2012-08-01

87

Pediatric craniovertebral junction trauma.  

PubMed

The craniovertebral junction consists of the occiput, atlas, and axis, along with their strong ligamentous attachments. Because of its unique anatomical considerations, trauma to the craniovertebral junction requires specialized care. Children with potential injuries to the craniovertebral junction and cervical spinal cord demand specific considerations compared to adult patients. Prehospital immobilization techniques, diagnostic studies, and spinal injury patterns among young children can be different from those in adults. This review highlights the unique aspects in diagnosis and management of children with real or potential craniovertebral junction injuries. PMID:24265053

Oppenlander, Mark E; Clark, Justin C; Sonntag, Volker K H; Theodore, Nicholas

2014-01-01

88

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

89

Optimal junction Trees  

Microsoft Academic Search

The paper deals with optimality issues in connectionwith updating beliefs in networks. Weaddress two processes: triangulation and constructionof junction trees. In the first part,we give a simple algorithm for constructingan optimal junction tree from a triangulatednetwork. In the second part, we argue thatany exact method based on local calculationsmust either be less efficient than the junctiontree method, or it has

Finn Verner Jensen; Frank Jensen

1994-01-01

90

A Kinetic Monte Carlo model for material aging: Simulations of second phase formation at Au/Bi2Te3 junction in oxygen environments  

NASA Astrophysics Data System (ADS)

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/Bi2Te3 interface under oxygen and oxygen-free environments, and the results are compared with the corresponding experiments.

Zhou, X. W.; Yang, N. Y. C.

2014-03-01

91

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

92

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

NASA Astrophysics Data System (ADS)

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

Matenco, L. C.; Radivojevic, D.

2012-04-01

93

Oxidative Stress, Lens Gap Junctions, and Cataracts  

PubMed Central

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

Beyer, Eric C.

2009-01-01

94

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

95

Rectosigmoid Junction Coding Guidelines  

Cancer.gov

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

96

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

97

Low Energy Implantation for Medium Current Implanter with Molecular Ions  

NASA Astrophysics Data System (ADS)

Ion implantation is now indispensable process for semiconductor device fabrication. One of the key issues for the next generation LSI device fabrication is the formation of ultra shallow junction using Boron implantation. Medium current ion implanter for LSI production use can dope ions to the device wafer with accurately controlled uniformity and incident angle at a variety of energy ranges. However, the productivity of LSI at sub-keV energy region with conventional atomic B+ implantation will quickly fall down due to the low beam current caused by the well-known space charge limitation. To achieve a high productivity in this energy region, Decaborane (B10Hx+) implantation is supposed to be an appropriate solution. We are to review the technologies used for the commercial medium current ion implanter including Decaborane implantation for ultra shallow junction formation.

Nagai, Nobuo; Sakai, Shigeki; Hamamoto, Nariaki; Naito, Masao

2003-08-01

98

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

99

Metal-free molecular junctions on ITO via amino-silane binding—towards optoelectronic molecular junctions  

NASA Astrophysics Data System (ADS)

Light control over currents in molecular junctions is desirable as a non-contact input with high spectral and spatial resolution provided by the photonic input and the molecular electronics element, respectively. Expanding the study of molecular junctions to non-metallic transparent substrates, such as indium tin oxide (ITO), is vital for the observation of molecular optoelectronic effects. Non-metallic electrodes are expected to decrease the probability of quenching of molecular photo-excited states, light-induced plasmonic effects, or significant electrode expansion under visible light. We have developed micron-sized, metal free, optically addressable ITO molecular junctions with a conductive polymer serving as the counter-electrode. The electrical transport was shown to be dominated by the nature of the self-assembled monolayer (SAM). The use of amino-silane (APTMS) as the chemical binding scheme to ITO was found to be significant in determining the transport properties of the junctions. APTMS allows high junction yields and the formation of dense molecular layers preventing electrical short. However, polar amino-silane binding to the ITO significantly decreased the conductance compared to thiol-bound SAMs, and caused tilted geometry and disorder in the molecular layer. As the effect of the molecular structure on transport properties is clearly observed in our junctions, such metal-free junctions are suitable for characterizing the optoelectronic properties of molecular junctions.

Sergani, S.; Furmansky, Y.; Visoly-Fisher, I.

2013-11-01

100

A high performance 50 nm PMOSFET using decaborane (B10H 14) ion implantation and 2-step activation annealing process  

Microsoft Academic Search

A high performance 50 nm PMOSFET with 7-nm-deep ultra shallow junction is described. Ultra-low energy implantation of B10H(14+) at 2 keV (effective energy of boron is 0.2 keV) which never causes transient enhanced diffusion (TED) is utilized for the extension formation. To prevent thermal diffusion (TD), we developed a 2-step activation annealing process (2-step AAP) which forms a shallow extension

K.-I. Goto; J. Matsuo; Y. Tada; T. Tanaka; Y. Momiyama; T. Sugii; I. Yamada

1997-01-01

101

Low-energy implantations of decaborane (B10H14) ion clusters in silicon wafers  

Microsoft Academic Search

Low-energy implantation with decaborane (B10H14 ) ion clusters is suitable for ultra-shallow junction formation. Using a high-voltage research implanter with a microwave ion source, decaborane implantation has been performed at energies in the range 2.8 to 440 keV, with doses up to 1014 decaborane\\/cm2 (1015 B atoms\\/cm2). A study of the implantation damage shows that the number of displaced Si

A. G. Dirks; P. H. L. Bancken; J. Politiek; N. E. B. Cowern; J. H. M. Snijders; J. G. M. Van Berkum; M. A. Verheijen

1998-01-01

102

Tight junctions and human diseases  

Microsoft Academic Search

Tight junctions are intercellular junctions adjacent to the apical end of the lateral membrane surface. They have two functions, the barrier (or gate) function and the fence function. The barrier function of tight junctions regulates the passage of ions, water, and various macromolecules, even of cancer cells, through paracellular spaces. The barrier function is thus relevant to edema, jaundice, diarrhea,

Norimasa Sawada; Masaki Murata; Keisuke Kikuchi; Makoto Osanai; Hirotoshi Tobioka; Takashi Kojima; Hideki Chiba

2003-01-01

103

Measurement of Tunnel Junction Resistance during Formation  

E-print Network

and wire­bonding of the device. Under the assumption that oxygen was diffusing through the electrodes, we silicon nitride by reactive sputtering. All films are deposited in a stainless­steel vacuum chamber with the device. We have not been able to discover the mechanism: oxygen diffusing through the electrodes

Bland, Roger

104

Electromagnetic fast firing for ultrashallow junction formation  

Microsoft Academic Search

The creation of low resistivity, ultrashallow source\\/drain regions in MOS device structures requires rapid thermal processing (RTP) techniques that restrict diffusion and activate a significant percentage of the implanted dopant species. While current heating techniques depend upon illumination based heating, a new technology, electromagnetic induction heating (EMIH), achieves a rapid heating of the silicon by coupling electromagnetic radiation directly into

Keith Thompson; John H. Booske; Reid F. Cooper; Yogesh B. Gianchandani

2003-01-01

105

Cluster ion implantation for shallow junction formation  

SciTech Connect

The implantation of Ar and B into Si by cluster ion has been examined. Shallow implantation was clearly demonstrated with a high energy cluster ion. The damage layer thickness is less than 200{angstrom}, when 150keV Ar cluster ions are implanted into Si. This thickness is one order of magnitude smaller than that by Ar monomer ion bombardment with the same total energy. The thickness of the damaged layer formed by cluster ion bombardment increased with the cluster size, when the total energy of cluster ion remain the same. This is one of the non-linear effect of cluster implantation. Poly-atomic cluster-ion implantation with decaborane has also been demonstrated. Shallow implantation (<0.05 {mu}m) can be achieved by decaborane (B{sub 10}H{sub 14}) ions. The sheet resistance of the sample reached a few hundred {Omega}/{open_square} after annealing at 1000{degrees}C for 10s.

Matsuo, Jiro; Takeuchi, Daisuke; Aoki, Takaaki; Yamada, Isao [Kyoto Univ., Sakyo (Japan)

1996-12-31

106

Paranodal junction formation and spermatogenesis require sulfoglycolipids  

Microsoft Academic Search

Mammalian sulfoglycolipids comprise two major members, sulfatide (HSO3-3-galactosylceramide) and seminolipid (HSO3-3-monogalactosylalkylacylglycerol). Sulfatide is a major lipid component of the myelin sheath and serves as the epitope for the well known oligodendrocyte-marker antibody O4. Seminolipid is synthesized in spermatocytes and maintained in the subsequent germ cell stages. Both sulfoglycolipids can be synthesized in vitro by using the isolated cerebroside sulfotransferase. To

Koichi Honke; Yukie Hirahara; Jeffrey Dupree; Kinuko Suzuki; Brian Popko; Kikuro Fukushima; Junko Fukushima; Takashi Nagasawa; Nobuaki Yoshida; Yoshinao Wada; Naoyuki Taniguchi

2002-01-01

107

Phosphatase regulation of intercellular junctions  

PubMed Central

Intercellular junctions represent the key contact points and sites of communication between neighboring cells. Assembly of these junctions is absolutely essential for the structural integrity of cell monolayers, tissues and organs. Disruption of junctions can have severe consequences such as diarrhea, edema and sepsis, and contribute to the development of chronic inflammatory diseases. Cell junctions are not static structures, but rather they represent highly dynamic micro-domains that respond to signals from the intracellular and extracellular environments to modify their composition and function. This review article will focus on the regulation of tight junctions and adherens junctions by phosphatase enzymes that play an essential role in preserving and modulating the properties of intercellular junction proteins. PMID:24868494

McCole, Declan F

2013-01-01

108

Force and Conductance Spectroscopy of Single Molecule Junctions  

NASA Astrophysics Data System (ADS)

Investigation of mechanical properties of single molecule junctions is crucial to develop an understanding and enable control of single molecular junctions. This work presents an experimental and analytical approach that enables the statistical evaluation of force and simultaneous conductance data of metallic atomic point contacts and molecular junctions. A conductive atomic force microscope based break junction technique is developed to form single molecular junctions and collect conductance and force data simultaneously. Improvements of the optical components have been achieved through the use of a super-luminescent diode, enabling tremendous increases in force resolution. An experimental procedure to collect data for various molecular junctions has been developed and includes deposition, calibration, and analysis methods. For the statistical analysis of force, novel approaches based on two dimensional histograms and a direct force identification method are presented. The two dimensional method allows for an unbiased evaluation of force events that are identified using corresponding conductance signatures. This is not always possible however, and in these situations, the force based identification of junction rearrangement events is an attractive alternative method. This combined experimental and analytical approach is then applied to three studies: First, the impact of molecular backbones to the mechanical behavior of single molecule junctions is investigated and it is found that junctions formed with identical linkers but different backbone structure result in junctions with varying breaking forces. All molecules used show a clear molecular signature and force data can be evaluated using the 2D method. Second, the effects of the linker group used to attach molecules to gold electrodes are investigated. A study of four alkane molecules with different linkers finds a drastic difference in the evolution of donor-acceptor and covalently bonded molecules respectively. In fact, the covalent bond is found to significantly distort the metal electrode rearrangement such that junction rearrangement events can no longer be identified with a clean and well defined conductance signature. For this case, the force based identification process is used. Third, results for break junction measurements with different metals are presented. It is found that silver and palladium junctions rupture with forces different from those of gold contacts. In the case of silver experiments in ambient conditions, we can also identify oxygen impurities in the silver contact formation process, leading to force and conductance measurements of silver-oxygen structures. For the future, this work provides an experimental and analytical foundation that will enable insights into single molecule systems not previously accessible.

Frei, Michael

109

Physiology and Function of the Tight Junction  

PubMed Central

Understanding of tight junctions has evolved from their historical perception as inert solute barriers to recognition of their physiological and biochemical complexity. Many proteins are specifically localized to tight junctions, including cytoplasmic actin-binding proteins and adhesive transmembrane proteins. Among the latter are claudins, which are critical barrier proteins. Current information suggests that the paracellular barrier is most usefully modeled as having two physiologic components: a system of charge-selective small pores, 4 Å in radius, and a second pathway created by larger discontinuities in the barrier, lacking charge or size discrimination. The first pathway is influenced by claudin expression patterns and the second is likely controlled by different proteins and signals. Recent information on claudin function and disease-causing mutations have led to a more complete understanding of their role in barrier formation, but progress is impeded by lack of high resolution structural information. PMID:20066090

Anderson, James M.; Van Itallie, Christina M.

2009-01-01

110

Light emission studies of total dose and hot carrier effects on silicon junctions  

SciTech Connect

Electrical characteristics of silicon light emitting devices are changed in similar ways by X-irradiation and hot carrier stresses. Extended hot carrier stress alone causes, coalescence of light emission consistent with junction-localized boron passivation by liberated hydrogen. Optical characterization studies demonstrate the formation of junction micro-environments under hot carrier stress.

Kerns, S.; Jiang, D.; Bardonnie, M. de la [and others] [and others

1999-12-01

111

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

112

Characterization of GaP pyramidal textured p- n junctions  

NASA Astrophysics Data System (ADS)

GaP pyramidal textured p- n junction (PTJ) diodes prepared using liquid phase epitaxy growth were characterized using field-emission scanning electron microscopy (FE-SEM), electron beam induced current (EBIC), I- V and C- V measurements. FE-SEM images of cross-sectional surfaces of the PTJ diode showed sharp textured p- n junction interfaces and flat surfaces. EBIC analysis proved that the current collection follows the textured junction profiles. I- V characteristics of GaP PTJ and flat junction (FJ) diodes prepared under the same conditions both demonstrated very low leakage current, indicating that the formation of PTJ does not introduce extra structure-related defects. Analysis of C- V measurement indicated a 25% increase in junction interface area for the PTJ compared with the flat junction devices, in agreement with the estimated area increase of the textured surfaces. The ? particle irradiation response of a PTJ device showed an 88% increase in short circuit current as compared with that of a FJ counterpart.

Mei, X.; Ruda, H. E.; Berdinskihk, T.; Buchanan, M.

1999-04-01

113

PCBS AND TIGHT JUNCTION EXPRESSION  

PubMed Central

Polychlorinated biphenyl (PCB) congeners exhibit a broad range of adverse biological effects including neurotoxicity. The mechanisms by which PCBs cause neurotoxic effects are still not completely understood. The blood-brain barrier (BBB) is a physical and metabolic barrier separating brain microenvironment from the peripheral circulation and is mainly composed of endothelial cells connected by tight junctions. We examined the effects of several highly-chlorinated PCB congeners on expression of tight junction proteins in human brain endothelial cells. Treatment for 24 h with selective PCB congeners disrupted expression of the cytosolic scaffold proteins of tight junctions, such as zonula occludens (ZO)-1, ZO-2, and AF6. In contrast, PCB exposure did not alter expression of integral membrane proteins, junctional adhesion molecule-A (JAM-A), and claudin-1. Based on these data, we suggest that PCB-mediated selective alterations of tight junction protein expression may contribute to their neurotoxic effects in the central nervous system. PMID:18438464

Eum, Sung Yong; András, Ibolya E.; Couraud, Pierre-Olivier; Hennig, Bernhard; Toborek, Michal

2008-01-01

114

Probing Electronic and Thermoelectric Properties of Single Molecule Junctions  

NASA Astrophysics Data System (ADS)

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

Widawsky, Jonathan R.

115

A Novel Role for Embigin to Promote Sprouting of Motor Nerve Terminals at the Neuromuscular Junction*S?  

PubMed Central

Adult skeletal muscle accepts ectopic innervation by foreign motor axons only after section of its own nerve, suggesting that the formation of new neuromuscular junctions is promoted by muscle denervation. With the aim to identify new proteins involved in neuromuscular junction formation we performed an mRNA differential display on innervated versus denervated adult rat muscles. We identified transcripts encoding embigin, a transmembrane protein of the immunoglobulin superfamily (IgSF) class of cell adhesion molecules to be strongly regulated by the state of innervation. In innervated muscle it is preferentially localized to neuromuscular junctions. Forced overexpression in innervated muscle of a full-length embigin transgene, but not of an embigin fragment lacking the intracellular domain, promotes nerve terminal sprouting and the formation of additional acetylcholine receptor clusters at synaptic sites without affecting terminal Schwann cell number or morphology, and it delays the retraction of terminal sprouts following re-innervation of denervated endplates. Conversely, knockdown of embigin by RNA interference in wild-type muscle accelerates terminal sprout retraction, both by itself and synergistically with deletion of neural cell adhesion molecule. These findings indicate that embigin enhances neural cell adhesion molecule-dependent neuromuscular adhesion and thereby modulates neuromuscular junction formation and plasticity. PMID:19164284

Lain, Enzo; Carnejac, Soizic; Escher, Pascal; Wilson, Marieangela C.; Lømo, Terje; Gajendran, Nadesan; Brenner, Hans Rudolf

2009-01-01

116

Ion bipolar junction transistors  

PubMed Central

Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated. PMID:20479274

Tybrandt, Klas; Larsson, Karin C.; Richter-Dahlfors, Agneta; Berggren, Magnus

2010-01-01

117

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

PubMed Central

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

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

2013-01-01

118

Molecular Components of the Adherens Junction  

PubMed Central

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

Niessen, Carien M.; Gottardi, Cara J.

2008-01-01

119

Wnt Signaling in Neuromuscular Junction Development  

PubMed Central

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

Koles, Kate

2012-01-01

120

Josephson junction Q-spoiler  

DOEpatents

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

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

1988-01-01

121

Adherens junctions in endothelial cells regulate vessel maintenance and angiogenesis.  

PubMed

Cell to cell junctions direct endothelial responses both in quiescent and angiogenic vessels. Endothelial cells express both tight and adherens junctions. Although different in their specific molecular composition, these junctional complexes present a relatively similar structural and functional arrangement. Transmembrane adhesive proteins that bind homophilically identical molecules on adjacent cells represent the core component in both types of junctions. This intercellular recognition starts a sequence of signaling events. Signal transmission is mediated through the interaction with cytoplasmic and transmembrane partners. Adherens junctions are ubiquitous along the vascular tree. In these structures VE-cadherin and its intracellular partners mediate adhesion. In vitro and in vivo data show that VE-cadherin is required for endothelial integrity in quiescent vessels and for the correct organization of new vessels. VE-cadherin regulates endothelial functions through different mechanisms which include: (i) direct activation of signaling molecules such as PI3kinase and Rac, to sustain survival and organization of the actin cytoskeleton; (ii) regulation of gene transcription, possibly modulating the nuclear level of transcription co-factors such as beta-catenin and p120; (iii) formation of complexes with growth factor receptors, such as the type 2 receptor of VEGF (VEGFR-2) and modulation of their signaling properties. PMID:18023702

Lampugnani, Maria Grazia; Dejana, Elisabetta

2007-01-01

122

The Extracellular Architecture of Adherens Junctions Revealed by Crystal Structures of Type I Cadherins  

SciTech Connect

Adherens junctions, which play a central role in intercellular adhesion, comprise clusters of type I classical cadherins that bind via extracellular domains extended from opposing cell surfaces. We show that a molecular layer seen in crystal structures of E- and N-cadherin ectodomains reported here and in a previous C-cadherin structure corresponds to the extracellular architecture of adherens junctions. In all three ectodomain crystals, cadherins dimerize through a trans adhesive interface and are connected by a second, cis, interface. Assemblies formed by E-cadherin ectodomains coated on liposomes also appear to adopt this structure. Fluorescent imaging of junctions formed from wild-type and mutant E-cadherins in cultured cells confirm conclusions derived from structural evidence. Mutations that interfere with the trans interface ablate adhesion, whereas cis interface mutations disrupt stable junction formation. Our observations are consistent with a model for junction assembly involving strong trans and weak cis interactions localized in the ectodomain.

O Harrison; X Jin; S Hong; F Bahna; G Ahlsen; J Brasch; Y Wu; J Vendome; K Felsovalyi; et al.

2011-12-31

123

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

124

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

125

Novel shallow junction technology using decaborane (B\\/sub 10\\/H\\/sub 14\\/)  

Microsoft Academic Search

We have developed the first ever low-energy, high-dosage boron ion implantation technology using a decaborane (B 10H 14) molecule. Since B 10H 14 consists of ten boron atoms, they are implanted with about a one-tenth lower effective acceleration energy and a ten times higher effective beam current compared with those of boron. Using this implantation, we achieved an ultra-shallow 39-nm-deep

K. Goto; J. Matsuo; T. Sugii; H. Minakata; I. Yamada; T. Hisatsugu

1996-01-01

126

DEVELOPMENT OF THE NEUROMUSCULAR JUNCTION  

PubMed Central

To determine the effects of nerve explants on the integrity of motor end plates in vitro, cholinesterase activity and structure of end plates were compared in newt muscle denervated in vivo, cultured in the absence of nerve explants, and cultured in the presence of sensory ganglia. In neuromuscular junctions denervated in vivo or in vitro, the synaptic vesicles become clumped and fragmented. A few intact vesicles escape into the synaptic cleft. Axon terminals degenerate until they are left as residual bodies within the Schwann cell cytoplasm. Junctional folds on the muscle surface are reduced in height and are no longer evident once traces of axoplasm within the Schwann cell disappear. End plate cholinesterase activity is reduced as junctional folds are lost. When muscle is cultured in the presence of a sensory ganglion, the terminal axoplasm degenerates in the same manner but junctional folds persist on the muscle surface. Moderately intense cholinesterase activity remains in association with the junctional folds, so that normal motor end plates are maintained in the absence of innervation. These results show that degenerative changes in the structure of the motor end plate and loss of cholinesterase activity occurring in organ culture as a result of denervation can be retarded by nerve explants that do not directly innervate the muscle. PMID:4653422

Lentz, Thomas L.

1972-01-01

127

Interconverting Conformations of Slipped-DNA Junctions Formed by Trinucleotide Repeats Affect Repair Outcome  

PubMed Central

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

2013-01-01

128

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

129

Processing of intermediates in recombination and DNA repair: identification of a new endonuclease that specifically cleaves Holliday junctions.  

PubMed Central

The formation and subsequent resolution of Holliday junctions are critical stages in recombination. We describe a new Escherichia coli endonuclease that resolves Holliday intermediates by junction cleavage. The 14 kDa Rus protein binds DNA containing a synthetic four-way junction (X-DNA) and introduces symmetrical cuts in two strands to give nicked duplex products. Rus also processes Holliday intermediates made by RecA into products that are characteristic of junction resolution. The cleavage activity on X-DNA is remarkably similar to that of RuvC. Both proteins preferentially cut the same two strands at the same location. Increased expression of Rus suppresses the DNA repair and recombination defects of ruvA, ruvB and ruvC mutants. We conclude that all ruv strains are defective in junction cleavage, and discuss pathways for Holliday junction resolution by RuvAB, RuvC, RecG and Rus. Images PMID:7813450

Sharples, G J; Chan, S N; Mahdi, A A; Whitby, M C; Lloyd, R G

1994-01-01

130

The kidney tight junction (Review)  

PubMed Central

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

HOU, JIANGHUI

2014-01-01

131

The kidney tight junction (Review).  

PubMed

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

Hou, Jianghui

2014-12-01

132

Magnetic switching and magnetoresistance in nanoscale spin tunnel junctions  

E-print Network

Magnetic switching and magneto­resistance in nano­scale spin tunnel junctions D. B. Haviland, M multi­junction arrays and double­tunnel junction geometries have been studied. The junctions ex­ hibit

Haviland, David

133

Gap Junctional Communication Modulates Gene Expression in Osteoblastic Cells  

PubMed Central

Bone-forming cells are organized in a multicellular network interconnected by gap junctions. In these cells, gap junctions are formed by connexin43 (Cx43) and connexin45 (Cx45). Cx43 gap junctions form pores that are more permeable to negatively charged dyes such as Lucifer yellow and calcein than are Cx45 pores. We studied whether altering gap junctional communication by manipulating the relative expression of Cx43 and Cx45 affects the osteoblast phenotype. Transfection of Cx45 in cells that express primarily Cx43 (ROS 17/2.8 and MC3T3-E1) decreased both dye transfer and expression of osteocalcin (OC) and bone sialoprotein (BSP), genes pivotal to bone matrix formation and calcification. Conversely, transfection of Cx43 into cells that express predominantly Cx45 (UMR 106–01) increased both cell coupling and expression of OC and BSP. Transient cotransfection of promoter–luciferase constructs and connexin expression vectors demonstrated that OC and BSP gene transcription was down-regulated by Cx45 cotransfection in ROS 17/2.8 and MC3T3-E1 cells, in association with a decrease in dye coupling. Conversely, cotransfection of Cx43 in UMR 106–01 cells up-regulated OC and BSP gene transcription. Activity of other less specific osteoblast promoters, such as osteopontin and osteonectin, was less sensitive to changes in gap junctional communication. Thus, altering gap junctional permeability by manipulating the expression of Cx43 and Cx45 in osteoblastic cells alters transcriptional activity of osteoblast-specific promoters, presumably via modulation of signals that can diffuse from cell to cell. A communicating intercellular network is required for the full elaboration of a differentiated osteoblastic phenotype. PMID:9693379

Lecanda, Fernando; Towler, Dwight A.; Ziambaras, Konstantinos; Cheng, Su-Li; Koval, Michael; Steinberg, Thomas H.; Civitelli, Roberto

1998-01-01

134

Gap junctional communication modulates gene expression in osteoblastic cells.  

PubMed

Bone-forming cells are organized in a multicellular network interconnected by gap junctions. In these cells, gap junctions are formed by connexin43 (Cx43) and connexin45 (Cx45). Cx43 gap junctions form pores that are more permeable to negatively charged dyes such as Lucifer yellow and calcein than are Cx45 pores. We studied whether altering gap junctional communication by manipulating the relative expression of Cx43 and Cx45 affects the osteoblast phenotype. Transfection of Cx45 in cells that express primarily Cx43 (ROS 17/2.8 and MC3T3-E1) decreased both dye transfer and expression of osteocalcin (OC) and bone sialoprotein (BSP), genes pivotal to bone matrix formation and calcification. Conversely, transfection of Cx43 into cells that express predominantly Cx45 (UMR 106-01) increased both cell coupling and expression of OC and BSP. Transient cotransfection of promoter-luciferase constructs and connexin expression vectors demonstrated that OC and BSP gene transcription was down-regulated by Cx45 cotransfection in ROS 17/2. 8 and MC3T3-E1 cells, in association with a decrease in dye coupling. Conversely, cotransfection of Cx43 in UMR 106-01 cells up-regulated OC and BSP gene transcription. Activity of other less specific osteoblast promoters, such as osteopontin and osteonectin, was less sensitive to changes in gap junctional communication. Thus, altering gap junctional permeability by manipulating the expression of Cx43 and Cx45 in osteoblastic cells alters transcriptional activity of osteoblast-specific promoters, presumably via modulation of signals that can diffuse from cell to cell. A communicating intercellular network is required for the full elaboration of a differentiated osteoblastic phenotype. PMID:9693379

Lecanda, F; Towler, D A; Ziambaras, K; Cheng, S L; Koval, M; Steinberg, T H; Civitelli, R

1998-08-01

135

Laser beam induced current microscopy and photocurrent mapping for junction characterization of infrared photodetectors  

NASA Astrophysics Data System (ADS)

For non-destructive optical characterization, laser beam induced current (LBIC) microscopy has been developed into as a quantitative tool to examine individual photodiodes within a large pixel array. Two-dimensional LBIC microscopy, also generally called photocurrent mapping (PC mapping), can provide spatially resolved information about local electrical properties and p-n junction formation in photovoltaic infrared (including visible light) photodetectors from which it is possible to extract material and device parameters such as junction area, junction depth, diffusion length, leakage current position and minority carrier diffusion length etc. This paper presents a comprehensive review of research background, operating principle, fundamental issues, and applications of LBIC or PC mapping.

Qiu, WeiCheng; Hu, WeiDa

2015-02-01

136

Laser beam induced current microscopy and photocurrent mapping for junction characterization of infrared photodetectors  

NASA Astrophysics Data System (ADS)

For non-destructive optical characterization, laser beam induced current (LBIC) microscopy has been developed into as a quantitative tool to examine individual photodiodes within a large pixel array. Two-dimensional LBIC microscopy, also generally called photocurrent mapping (PC mapping), can provide spatially resolved information about local electrical properties and p-n junction formation in photovoltaic infrared (including visible light) photodetectors from which it is possible to extract material and device parameters such as junction area, junction depth, diffusion length, leakage current position and minority carrier diffusion length etc. This paper presents a comprehensive review of research background, operating principle, fundamental issues, and applications of LBIC or PC mapping.

Qiu, WeiCheng; Hu, WeiDa

2014-12-01

137

Thermally induced 0-pi phase transition in Josephson junctions through a ferromagnetic oxide film  

E-print Network

We investigate the Josephson transport through a ferromagnetic oxide film, e.g., La$_2$BaCuO$_5$, theoretically. Using the recursive Green's function technique, we found the formation of a pi-junction in such systems. Moreover the 0-pi phase transition is induced by increasing the temperature. Such ferromagnetic-oxide based Josephson junctions may become an element in the architecture of future quantum computers.

Shiro Kawabata; Yasuhiro Asano; Alexander A. Golubov; Yukio Tanaka; Satoshi Kashiwaya

2010-10-01

138

Conductance of Alkanedithiol Single-Molecule Junctions: A Molecular Dynamics Study  

Microsoft Academic Search

We study the formation and conductance of alkanedithiol molecular wire junctions using density- functional based molecular dynamics and non-equilibrium Green's function techniques. The stretch- ing of the junction involves straightening of the wire, migration of thiol end-groups on the Au contact surfaces and pulling out of Au atoms. The low-bias conductance traces show clear plateaux which magnitude is found to

Magnus Paulsson; Casper Krag; Thomas Frederiksen; Mads Brandbyge

2009-01-01

139

Superconducting Tunnelling in Metal-Semiconductor Junctions  

Microsoft Academic Search

Superconducting tunnelling effects were observed for mechanically contacted Nb-Si, Pb-Si, and Nb-GaAs junctions. The I-V curves of Nb-Si junctions largely deviate from the usual BCS curve. Deviations for Nb-GaAs and Pb-Si junctions are much smaller than that for a Nb-Si junction. This large deviation is explained by the uniformly distributed surface states on the boundary. The upper critical fields Hc2

Nobuo Tsuda

1969-01-01

140

Unexpected Roles of the Na-K-ATPase and Other Ion Transporters in Cell Junctions and Tubulogenesis  

NSDL National Science Digital Library

Recent work shows that transport-independent as well as transport-dependent functions of ion transporters, and in particular the Na-K-ATPase, are required for formation and maintenance of several intercellular junctions. Furthermore, these junctional and other nonjunctional functions of ion transporters contribute to development of epithelial tubes. Here, we consider what has been learned about the roles of ion pumps in formation of junctions and epithelial tubes in mammals, zebrafish, Drosophila, and C. elegans. We propose that asymmetric association of the Na-K-ATPase with cell junctions early in metazoan evolution enabled vectorial transcellular ion transport and control of intraorganismal environment. Ion transport-independent functions of the Na-K-ATPase arose as junctional complexes evolved.

Thomas Krupinski (Department of Biochemistry, Molecular Biology, and Cell Biology)

2009-06-01

141

Parallel p-n junctions across nanowires by one-step ex situ doping.  

PubMed

The bottom-up synthesis of nanoscale building blocks is a versatile approach for the formation of a vast array of materials with controlled structures and compositions. This approach is one of the main driving forces for the immense progress in materials science and nanotechnology witnessed over the past few decades. Despite the overwhelming advances in the bottom-up synthesis of nanoscale building blocks and the fine control of accessible compositions and structures, certain aspects are still lacking. In particular, the transformation of symmetric nanostructures to asymmetric nanostructures by highly controlled processes while preserving the modified structural orientation still poses a significant challenge. We present a one-step ex situ doping process for the transformation of undoped silicon nanowires (i-Si NWs) to p-type/n-type (p-n) parallel p-n junction configuration across NWs. The vertical p-n junctions were measured by scanning tunneling microscopy (STM) in concert with scanning tunneling spectroscopy (STS), termed STM/S, to obtain the spatial electronic properties of the junction formed across the NWs. Additionally, the parallel p-n junction configuration was characterized by off-axis electron holography in a transmission electron microscope to provide an independent verification of junction formation. The doping process was simulated to elucidate the doping mechanisms involved in the one-step p-i-n junction formation. PMID:25030217

Hazut, Ori; Huang, Bo-Chao; Pantzer, Adi; Amit, Iddo; Rosenwaks, Yossi; Kohn, Amit; Chang, Chia-Seng; Chiu, Ya-Ping; Yerushalmi, Roie

2014-08-26

142

Development of synaptic junctions in cerebellar glomeruli.  

PubMed

In the glomerular synapses of developing mouse cerebellar cortex, 2 components of the synaptic junctions assemble independently in the immature granule cell dendrites, and then combine. 'Initial' junctions between mossy fiber axons and immature granule cell dendrites have presynaptic and postsynaptic electron-dense fuzz and a widened synaptic cleft, but lack the aggregate of intramembrane particles associated with the extracellular half of the postsynaptic membrane which characterizes mature synaptic junctions. In the vicinity of 'initial junctions' there are particle aggregates which resemble those at mature synaptic junctions, but which are less densely packed and which are not associated with the other features of a junction. The constituent particles of these aggregates move to the sites of 'initial junctions' to combine with them and form 'immature synaptic junctions'. Many of these immature junctions are larger in area than mature synaptic junctions. The immature junctions accumulate a fairly uniform complement of intramembrane particles, which increase in packing density as the junctions decrease in area and attain smaller, adult size. PMID:6871725

Landis, D M; Weinstein, L A; Halperin, J J

1983-06-01

143

Thin Junction Trees Francis R. Bach  

E-print Network

Thin Junction Trees Francis R. Bach Computer Science Division University of California Berkeley, CA with thin junction trees--models that are characterized by an upper bound on the size of the maximal cliques of their triangulated graph. By ensuring that the junction tree is thin, inference in our models remains tractable

Bach, Francis

144

Thin Junction Trees Francis R. Bach  

E-print Network

Thin Junction Trees Francis R. Bach Computer Science Division University of California Berkeley, CA with thin junction trees---models that are characterized by an upper bound on the size of the maximal cliques of their triangulated graph. By ensuring that the junction tree is thin, inference in our models

Jordan, Michael I.

145

GAP JUNCTION FUNCTION AND CANCER  

EPA Science Inventory

Gap Junctions (GJs) provide cell-to-cell communication (GJIC) of essential metabolites and ions. Js allow tissues to average responses, clear waste products, and minimize the effects of xenobiotics by dilution and allowing steady-state catabolism. any chemicals can adversely affe...

146

The Yolla Bolly junction revisited  

SciTech Connect

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

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

1993-04-01

147

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); Arthur Shulkes (University of Melbourne Department of Surgery and Austin Health; REV); Graham S. Baldwin (University of Melbourne Department of Surgery and Austin Health; REV)

2005-03-29

148

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

PubMed Central

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

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

2012-01-01

149

Nature of well-defined conductance of amine-anchored molecular junctions: Density functional calculations  

NASA Astrophysics Data System (ADS)

Amine-terminated molecules show well-behaved conductance in the scanning tunneling microscope break-junction experimental measurements. We performed density functional theory based electron transport calculations to explain the nature of this phenomenon. We find that amines can be adsorbed only on the apex Au atom, while the thiolate group can be attached equally well to undercoordinated and clean Au surfaces. Our calculations show that only one adsorption geometry is sterically and energetically possible for the amine-anchored junction whereas three different adsorption geometries with very distinct transport properties are almost equally probable for the thiolate-anchored junction. We calculated the conductance as a function of the junction stretching when the molecules are pulled by the scanning tunneling microscope tip from the Au electrode. Our calculations show that the stretching of the thiolate-anchored junction during its formation is accompanied by significant electrode geometry distortion. The amine-anchored junctions exhibit very different behavior—the electrode remains intact when the scanning tunneling microscope tip stretches the junction.

Li, Zhenyu; Kosov, D. S.

2007-07-01

150

AII amacrine cells discriminate between heterocellular and homocellular locations when assembling connexin36-containing gap junctions  

PubMed Central

ABSTRACT Electrical synapses (gap junctions) rapidly transmit signals between neurons and are composed of connexins. In neurons, connexin36 (Cx36) is the most abundant isoform; however, the mechanisms underlying formation of Cx36-containing electrical synapses are unknown. We focus on homocellular and heterocellular gap junctions formed by an AII amacrine cell, a key interneuron found in all mammalian retinas. In mice lacking native Cx36 but expressing a variant tagged with enhanced green fluorescent protein at the C-terminus (KO-Cx36-EGFP), heterocellular gap junctions formed between AII cells and ON cone bipolar cells are fully functional, whereas homocellular gap junctions between two AII cells are not formed. A tracer injected into an AII amacrine cell spreads into ON cone bipolar cells but is excluded from other AII cells. Reconstruction of Cx36–EGFP clusters on an AII cell in the KO-Cx36-EGFP genotype confirmed that the number, but not average size, of the clusters is reduced – as expected for AII cells lacking a subset of electrical synapses. Our studies indicate that some neurons exhibit at least two discriminatory mechanisms for assembling Cx36. We suggest that employing different gap-junction-forming mechanisms could provide the means for a cell to regulate its gap junctions in a target-cell-specific manner, even if these junctions contain the same connexin. PMID:24463820

Meyer, Arndt; Hilgen, Gerrit; Dorgau, Birthe; Sammler, Esther M.; Weiler, Reto; Monyer, Hannah; Dedek, Karin; Hormuzdi, Sheriar G.

2014-01-01

151

Morphogenesis of rat myotendinous junction  

PubMed Central

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

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

2013-01-01

152

Adherens junctions during cell migration.  

PubMed

Migration is a key cellular process, involved during morphogenetic movements as well as in the adult where it participates in immune cell trafficking, wound healing or tumour invasion. As they migrate, cells interact with a microenvironment composed of extracellular matrix and neighbouring cells. Cell-cell adhesions ensure tissue integrity while they allow migration of single or grouped cells within this tissue. Cadherin and nectin-based adherens junctions are key players in intercellular interactions. They are used as adhesive complexes whose mechanical properties improve cell coordination during collective migration and promote cell motility on cadherin substrates. In addition, adherens junctions transduce signals that actively participate in the control of directed cell migration, by providing polarity cues and also participating in contact inhibition of motility. PMID:22674074

Etienne-Manneville, Sandrine

2012-01-01

153

ABERRANT DEVELOPMENT OF NEUROMUSCULAR JUNCTIONS IN GLYCOSYLATION-DEFECTIVE LARGEMYD MICE  

PubMed Central

Mice deficient in the glycosyltransferase Large are characterized by severe muscle and central nervous system abnormalities. In this study, we show that the formation and maintenance of neuromuscular junctions in Largemyd mice are greatly compromised. Neuromuscular junctions are not confined to the muscle endplate zone but are widely spread and are frequently accompanied by exuberant nerve sprouting. Nerve terminals are highly fragmented and binding of ?-bungarotoxin to postsynaptic acetylcholine receptors (AChRs) is greatly reduced. In vitro, Largemyd myotubes are responsive to agrin but produce aberrant AChR clusters, which are larger in area and less densely packed with AChRs. In addition, AChR expression on the cell surface is diminished suggesting that AChR assembly or transport is defective. These results together with the finding that O-linked glycosylation at neuromuscular junctions of Largemyd mice is compromised indicate that the action of Large is necessary for proper neuromuscular junction development. PMID:19346129

Herbst, Ruth; Iskratsch, Thomas; Unger, Ewald; Bittner, Reginald E.

2010-01-01

154

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

155

Calculations predict condensate movement at T junctions  

Microsoft Academic Search

A model for the prediction of the route preference of condensate at T junctions in gas-transportation pipelines has been developed. The double-stream model can be applied to sharpedged and radiused, regular, and reduced T and Y junctions. The model permits an understanding of condensate behavior at a junction. From this knowledge, precautions can be taken to install gas-liquid separators at

J. M. H. Fortuin; P. J. Hamersma; J. Hart; H. J. Smit; W. P. Baan

1991-01-01

156

Gap Junctions Couple Astrocytes and Oligodendrocytes  

PubMed Central

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

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

2009-01-01

157

RWGSCAT - RECTANGULAR WAVEGUIDE JUNCTION SCATTERING PROGRAM  

NASA Technical Reports Server (NTRS)

In order to optimize frequency response and determine the tolerances required to meet RF specifications, accurate computer modeling of passive rectangular waveguide components is often required. Many rectangular waveguide components may be represented either exactly or approximately as a number of different size rectangular waveguides which are connected in series. RWGSCAT, Rectangular WaveGuide junction SCATtering program, solves for the scattering properties of a waveguide device. This device must consist of a number of rectangular waveguide sections of different cross sectional area which are connected in series. Devices which fall into this category include step transformers, filters, and smooth or corrugated rectangular horns. RWGSCAT will model such devices and accurately predict the reflection and transmission characteristics, taking into account higher order (other than dominant TE 10) mode excitation if it occurs, as well as multiple reflections and stored energy at each discontinuity. For devices which are large with respect to the wavelength of operation, the characteristics of the device may be required for computing a higher order mode or a number of higher order modes exciting the device. Such interactions can be represented by defining a scattering matrix for each discontinuity in the device, and then cascading the individual scattering matrices in order to determine the scattering matrix for the overall device. The individual matrices are obtained using the mode matching method. RWGSCAT is written in FORTRAN 77 for IBM PC series and compatible computers running MS-DOS. It has been successfully compiled and implemented using Lahey FORTRAN 77 under MS-DOS. A sample MS-DOS executable is provided on the distribution medium. It requires 377K of RAM for execution. Sample input data is also provided on the distribution medium. The standard distribution medium for this program is one 5.25 inch 360K MS-DOS format diskette. The contents of the diskette are compressed using the PKWARE archiving tools. The utility to unarchive the files, PKUNZIP.EXE, is included. An electronic copy of the documentation is included on the distribution medium in LaTEX format. RWGSCAT is also offered as a bundle with a related program, CWGSCAT (Scattering Matrix Program for Circular WaveGuide Junctions). Please see the abstract for RWGSCAT/CWGSCAT (COS-10045) for information about the bundled package. RWGSCAT was developed in 1993 and is a copyrighted work with all copyright vested in NASA.

Hoppe, D. J.

1994-01-01

158

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

159

The Ly6 Protein Coiled Is Required for Septate Junction and Blood Brain Barrier Organisation in Drosophila  

PubMed Central

Background Genetic analysis of the Drosophila septate junctions has greatly contributed to our understanding of the mechanisms controlling the assembly of these adhesion structures, which bear strong similarities with the vertebrate tight junctions and the paranodal septate junctions. These adhesion complexes share conserved molecular components and have a common function: the formation of paracellular barriers restraining the diffusion of solutes through epithelial and glial envelopes. Methodology/Principal Findings In this work we characterise the function of the Drosophila cold gene, that codes for a protein belonging to the Ly6 superfamily of extracellular ligands. Analysis of cold mutants shows that this gene is specifically required for the organisation of the septate junctions in epithelial tissues and in the nervous system, where its contribution is essential for the maintenance of the blood-brain barrier. We show that cold acts in a cell autonomous way, and we present evidence indicating that this protein could act as a septate junction component. Conclusion/Significance We discuss the specific roles of cold and three other Drosophila members of the Ly6 superfamily that have been shown to participate in a non-redundant way in the process of septate junction assembly. We propose that vertebrate Ly6 proteins could fulfill analogous roles in tight junctions and/or paranodal septate junctions. PMID:21423573

Hijazi, Assia; Haenlin, Marc; Waltzer, Lucas; Roch, Fernando

2011-01-01

160

Self-aligned Ni-GaSb source/drain junctions for GaSb p-channel metal-oxide-semiconductor field-effect transistors  

NASA Astrophysics Data System (ADS)

We demonstrate self-aligned Ni-GaSb alloy source/drain (S/D) junctions for GaSb p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs). Ni-GaSb alloys are used as self-aligned S/D junctions for GaSb p-MOSFETs formed with low-temperature annealing at 250 °C. Low-temperature process is preferred to avoid temperature-induced problems, because GaSb MOS gate stacks can show better MOS interface properties with lowering process temperature. This low-temperature S/D formation allowed us to realize the normal transistor operation of GaSb p-MOSFETs. Ni-GaSb alloy junctions can show the low contact resistivity with shallow junction depth. Self-aligned Ni-GaSb alloy S/D junctions can be an appropriate S/D junction technology for GaSb p-MOSFETs.

Yokoyama, Masafumi; Nishi, Koichi; Kim, Sanghyeon; Yokoyama, Haruki; Takenaka, Mitsuru; Takagi, Shinichi

2014-03-01

161

Computer models of DNA four-way junctions.  

PubMed

A modeling scheme that combines a constrained backbone generating algorithm with simple hard-sphere packing calculations is offered to build the four-stranded structures of DNA found in Holliday junctions. Two standard B-DNA duplexes are oriented side by side with helix axes at different relative inclinations and then systematically rotated and translated to identify closely spaced contact-free states. Attempts are subsequently made to introduce a low-energy sugar-phosphate linkage that serves as the site of strand exchange between the two duplexes. The chemical connection is sought using an algorithm which identifies the possible arrangements of the intervening backbone torsions between arbitrarily positioned bases. The goal is to identify the multiple conformational solutions associated with a particular arrangement of neighboring DNA helices in the four-way junction rather than a single optimum structure. The methodology is general, in terms of accommodating four-way junctions with arms of variable conformation and chain length and of dimensions much greater than treated heretofore. The only deformation in the four-way structures relative to B-DNA occurs at the site of backbone exchange, with base stacking and Watson-Crick pairing completely preserved in all models. The arrangements of neighboring bases at these sites resemble the unusual conformational steps found in a number of small molecule nucleic acid crystal structures. An interesting outcome of the calculations is the formation of sterically acceptable four-arm Holliday junctions over a wide range of angles at the cross. The potential mobility of the Holliday junctions is inferred from visualization and energetic analysis of the various models. Long-range electrostatic energies based on different currently available treatments of the dielectric constant are used to estimate the conformational preferences and flexibility of the four-stranded structures. The various dielectric schemes, however, are not in complete agreement on the likely conformational variability of the four-way junctions. The structures suggest a possible mechanism for branch migration and detail a pathway linking the antiparallel uncrossed Holliday structure inferred from solution measurements and the parallel cross-packed helical arrangements observed in single-crystal X-ray studies. PMID:8068615

Srinivasan, A R; Olson, W K

1994-08-16

162

Gold-gold junction electrodes:the disconnection method.  

PubMed

The formation of gold-gold junction electrodes for application in electroanalysis is described here based on electro-deposition from a non-cyanide gold plating bath. Converging growth of two hemispherical gold deposits on two adjacent platinum microelectrodes (both 100 µm diameter in glass, ca. 45 µm gap) followed by careful etching in aqueous chloride solution was employed. During growth both gold hemispheres "connect" and during etching "disconnection" is evident in a drop in current. Gold-gold junctions with sub-micron gaps are formed and applied for the electroanalytical detection of sub-micromolar concentrations of hydroquinone in 0.1 M phosphate buffer pH 7 (E(rev) = 0.04 V vs. SCE) and sub-micromolar concentration of dopamine in 0.1 M phosphate buffer pH 7 (E(rev) = 0.14 V vs. SCE). The potential future uses in analysis and limitations of gold-gold junction electrodes are discussed. PMID:21898774

Dale, Sara E C; Vuorema, Anne; Ashmore, Ellen M Y; Kasprzyk-Horden, Barbara; Sillanpää, Mika; Denuault, Guy; Marken, Frank

2012-02-01

163

Magnetoresistance in Ferromagnet\\/Semimetal\\/Ferromagnet Junctions  

Microsoft Academic Search

Electrical conductance and magnetoresistance (MR) in ferromagnet (FM) junctions with a nonmagnetic (NM) spacer are calculated within the ballistic limit for the current perpendicular to the junction planes. Emphasis is placed on the roles of the electronic states of the NM spacer in the MR. The MR shows a maximum when the electronic structure of the NM spacer changes from

Akio Watanabe; Hiroyoshi Itoh; Jun-ichiro Inoue

2004-01-01

164

Estimating the junction temperature of AC LEDs  

Microsoft Academic Search

Light-emitting diodes operating on alternating current are gaining popularity in the LED industry, especially for lighting applications. Because junction temperature is a good predictor of LED performance, the availability of a method to accurately estimate the junction temperature of AC LEDs would be very useful. This study investigated a method in which a low reference current having a pulse width

Yi-Wei Liu; Asiri Jayawardena; Terence R. Klein; Nadarajah Narendran

2010-01-01

165

MOBILITY IN GRAND JUNCTION DAVID SCHRANK  

E-print Network

and the preparation of this report. The contributions of these individuals are acknowledged and appreciated. Colorado A .........................................................................................................45 #12;v LIST OF FIGURES 1 Peak Hour Mobility Levels on Grand Junction Arterial Streets ................2 2 Seven Arterial Corridors in Grand Junction .............................................5 3

166

Tight Junction Regulation in the Mammary Gland  

Microsoft Academic Search

Tight junctions form a narrow, continuous sealthat surrounds each endothelial and epithelial cell atthe apical border, and act to regulate the movement ofmaterial through the paracellular pathway. In the mammary gland, the tight junctions of thealveolar epithelial cells are impermeable duringlactation, and thus allow milk to be stored betweennursing periods without leakage of milk components from the lumen. Nonetheless mammary

Duy-Ai D. Nguyen; Margaret C. Neville

1998-01-01

167

Theoretical Design of Symmetrical Junction Stripline Circulators  

Microsoft Academic Search

The results of detailed calculations based on Bosma's theory of 3-port stripline circulators are presented. The analysis has been modified to enable the scattering matrix, and therefore the circulator bandwidth, to be found. The equations of the 4-port junction have been derived and an expression for the scattering matrix of the general m-port junction is given. A comparison of experimental

J. B. Davies; P. Cohen

1963-01-01

168

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

169

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

170

IMPLANTATION AND ACTIVATION OF ULTRA-SHALLOW BORON IN GERMANIUM BRADLEY R. YATES  

E-print Network

to Nick Rudawski with his imitations of those that shall go unmentioned; every instance of `gives credence, Rong Lin, and Ole Hansen have all assisted with acquiring data as well as writing manuscripts. I would

Florida, University of

171

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

E-print Network

with depth 117 Figure 7.1 Clay Center, Kansas site map 125 Figure 7.2 Diagram of water table before and after pumping 126 Figure 7.3 Plot of P-wave velocity versus water saturation 127 Figure 7.4 Illustration of patchy and uniform saturation..., leading to the introduction of a finite-difference algorithm for migration using the scalar wave equation (Claerbout, 1971 and 1972). 3D techniques have continued to evolve and have seen major strides since the 1970s. In 1993 CGG introduced the 5...

Sloan, Steven D.

2008-01-01

172

Bioavailability and Efficacy of a Gap Junction Enhancer (PQ7) in a Mouse Mammary Tumor Model  

PubMed Central

The loss of gap junctional intercellular communication is characteristic of neoplastic cells, suggesting that the restoration with a gap junction enhancer may be a new therapeutic treatment option with less detrimental effects than traditional antineoplastic drugs. A gap junction enhancer, 6-methoxy-8-[(2-furanylmethyl) amino]-4-methyl-5-(3-trifluoromethylphenyloxy) quinoline (PQ7), on the normal tissue was evaluated in healthy C57BL/6J mice in a systemic drug distribution study. Immunoblot analysis of the vital organs indicates a reduction in Cx43 expression in PQ7-treated animals with no observable change in morphology. Next the transgenic strain FVB/N-Tg(MMTV-PyVT) 634Mul/J (also known as PyVT) was used as a spontaneous mammary tumor mouse model to determine the biological and histological effects of PQ7 on tumorigenesis and metastasis at three stages of development: Pre tumor, Early tumor, and Late tumor formation. PQ7 was assessed to have a low toxicity through intraperitoneal administration, with the majority of the compound being detected in the heart, liver, and lungs six hours post injection. The treatment of tumor bearing animals with PQ7 had a 98% reduction in tumor growth, while also decreasing the total tumor burden compared to control mice during the Pre stage of development. PQ7 treatment increased Cx43 expression in the neoplastic tissue during Pre-tumor formation; however, this effect was not observed in Late stage tumor formation. This study shows that the gap junction enhancer, PQ7, has low toxicity to normal tissue in healthy C57BL/6J mice, while having clinical efficacy in the treatment of spontaneous mammary tumors of PyVT mice. Additionally, gap junctional intercellular communication and neoplastic cellular growth are shown to be inversely related, while treatment with PQ7 inhibits tumor growth through targeting gap junction expression. PMID:23776708

Shishido, Stephanie N.; Prasain, Keshar; Beck, Amanda; Nguyen, Thi D. T.; Hua, Duy H.; Nguyen, Thu Annelise

2013-01-01

173

Electrostatic control of thermoelectricity in molecular junctions.  

PubMed

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

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

2014-11-01

174

Is Reelin the Answer to Synapse Elimination at the Neuromuscular Junction?  

NSDL National Science Digital Library

The formation of mature neuronal circuits during development involves elimination of a large number of synapses by activity-dependent processes. A recent study suggests that synapse elimination at the neuromuscular junction is impaired in reeler mutant mice, which are lacking the extracellular matrix protein Reelin. In this process, Reelin acts through an unexpected, proteolytic mechanism that is independent of Disabled 1, a cytoplasmic factor that mediates Reelin signaling in the central nervous system. This Perspective discusses possible models for Reelin function in the framework of activity-dependent synapse elimination at the neuromuscular junction.

Ben Chih (Columbia University; Department of Physiology and Cellular Biophysics, and Center for Neurobiology and Behavior REV)

2003-10-21

175

Measuring single molecule conductance with break junctions.  

PubMed

Single-molecule conductance measurements made under potential control provide a critical link between chemical and molecular electronic data. These measurements are made possible by the STM break-junction method introduced recently, but questions remain about its reliability. Here we report the use of a logarithmic current-to-voltage converter to examine a wide range of currents in an STM break junction study of octanedithiol, clearly showing both the gold-quantum wire regime and the single molecule conductance regime. We find two sets of molecular currents that we tentatively ascribe to different bonding geometries of the molecules in the break junction. PMID:16512369

He, Jin; Sankey, Otto; Lee, Myeong; Tao, Nongjian; Li, Xiulan; Lindsay, Stuart

2006-01-01

176

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

177

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

178

Molecular mechanism of double Holliday junction dissolution  

PubMed Central

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

2014-01-01

179

Microwave Photon Counter Based on Josephson Junctions  

NASA Astrophysics Data System (ADS)

We describe progress in the development of a microwave photon counter based on the current biased Josephson junction; absorption of a single photon causes the junction to switch to the voltage state, producing a large and easily measured classical signal. We discuss a self-resetting bias scheme based on a superconducting kinetic inductor that causes the junction to reset automatically to the active state following photon absorption. We investigate detector quantum efficiency and dark rate, and discuss applications to mesoscopic noise and circuit quantum electrodynamics.

Ribeill, Guilhem; Patel, Umeshkumar; Suttle, Joseph; McDermott, Robert

2013-03-01

180

Magnetic switching and magnetoresistance in nanoscale spin tunnel junctions  

E-print Network

Magnetic switching and magnetoresistance in nanoscale spin tunnel junctions M. Urech,a) V magnetic tunnel junctions in both multijunction arrays and double-tunnel junction geometries have been studied. The junctions exhibit magnetoresistance MR and change their resistance by 10% depending

Haviland, David

181

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

182

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

183

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

184

Gravitational Wave Bursts from Cosmic Superstrings with Y-junctions  

E-print Network

Cosmic superstring loops generically contain strings of different tensions that meet at Y-junctions. These loops evolve non-periodically in time, and have cusps and kinks that interact with the junctions. We study the effect of junctions on the gravitational wave signal emanating from cosmic string cusps and kinks. We find that earlier results on the strength of individual bursts from cusps and kinks on strings without junctions remain largely unchanged, but junctions give rise to additional contributions to the gravitational wave signal coming from strings expanding at the speed of light at a junction and kinks passing through a junction.

P. Binetruy; A. Bohe; T. Hertog; D. A. Steer

2009-07-26

185

Acoustic modulation of droplet size in a T-junction  

NASA Astrophysics Data System (ADS)

We introduce an approach and describe the process of acoustically driven formation of droplets in a microfluidic T-junction. Our system allows for fast and precise control of drop volume over a wide range that is fully electrically triggered. We exploit the interaction of a surface acoustic wave (SAW) excited on a piezoelectric, transparent substrate with the fluid to adjust the size of drops in a continuous microflow in real time and relate SAW intensity and drop size. Our device operates in the squeezing regime at low capillary numbers. We describe the mechanism of SAW modulated formation of a monodisperse microemulsion that forms the basis for the integration of more complex operations useful for droplet fluidic systems.

Schmid, Lothar; Franke, Thomas

2014-03-01

186

Do ridge^ridge^fault triple junctions exist on Earth? Evidence from the Aden^Owen^Carlsberg junction in  

E-print Network

^ridge^fault (RRF) types on the basis of large-scale plate motions are the Azores triple junction between the Gloria; Bird etal.,1998; Klein etal., 2005), and in the Atlantic, the Azores and Bouvet junctions cor- respond of RRF triple junctions are known on Earth (Fig.1): (1) the Azores triple junction in the Atlan

Nicolas, Chamot-Rooke

187

Theory of quantum transport in Josephson junctions with a ferromagnetic insulator  

E-print Network

We investigate the Josephson transport through ferromagnetic insulators (FIs) by taking into account the band structure of FIs explicitly. Using the recursive Green's function method, we found the formation of a pi-junction in such systems. Moreover the atomic-scale 0-pi oscillation is induced by increasing the thickness of FI and its oscillation period is universal, i.e., just single atomic layer. Based on these results, we show that stable pi-state can be realized in junctions based on high-Tc superconductors with La$_2$BaCuO$_5$ barrier. Such FI-based Josephson junctions may become an element in the architecture of future quantum computers.

Shiro Kawabata; Yasuhiro Asano

2010-09-28

188

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

189

Genetics Home Reference: Junctional epidermolysis bullosa  

MedlinePLUS

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

190

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

191

Ideal graphene/silicon Schottky junction diodes.  

PubMed

The proper understanding of semiconductor devices begins at the metal-semiconductor interface. The metal/semiconductor interface itself can also be an important device, as Schottky junctions often forms when the doping in the semiconductors is low. Here, we extend the analysis of metal-silicon Schottky junctions by using graphene, an atomically thin semimetal. We show that a fundamentally new transport model is needed to describe the graphene-silicon Schottky junction. While the current-voltage behavior follows the celebrated ideal diode behavior, the details of the diode characteristics is best characterized by the Landauer transport formalism, suggesting that the injection rate from graphene ultimately determines the transport properties of this new Schottky junction. PMID:25000510

Sinha, Dhiraj; Lee, Ji Ung

2014-08-13

192

Silicon p-i-n junction fibers.  

PubMed

Flexible Si p-i-n junction fibers made by high pressure chemical vapor deposition offer new opportunities in textile photovoltaics and optoelectronics, as exemplified by their photovoltaic properties, gigahertz bandwidth for photodetection, and ability to waveguide light. PMID:23212830

He, Rongrui; Day, Todd D; Krishnamurthi, Mahesh; Sparks, Justin R; Sazio, Pier J A; Gopalan, Venkatraman; Badding, John V

2013-03-13

193

Quantum limited detection in tunnel junction mixers  

Microsoft Academic Search

A complete quantum generalization of microwave mixer theory is constructed for nonlinear single-particle tunnel junctions. The result represents a unification of the concepts used to describe these \\

JOHN R. TUCKER

1979-01-01

194

Computing Scattering Characteristics Of Waveguide Junctions  

NASA Technical Reports Server (NTRS)

Rectangular WaveGuide Junction SCATtering RWGSCAT computer program solves scattering properties of waveguide device. Modeled as assembly of rectangular waveguides of different cross sections. RWGSCAT written in FORTRAN 77.

Hoppe, Daniel J.; Manshadi, Farzin

1994-01-01

195

Scanning tunneling microscopy on cleaved silicon pn junctions  

Microsoft Academic Search

A scanning tunneling microscope (STM) was used in air on cleaved Si pn junctions for junction delineation. Two-dimensional STM scans of a 0.3-?m-deep pn junction localized the junction position to within 50 nm. One-dimensional scans of the same junction have a resolution of 7 nm. A dependence of the tunneling current on the local impurity concentration of the sample is

S. Kordic; E. J. van Loenen; D. Dijkkamp; A. J. Hoeven; H. K. Moraal

1989-01-01

196

CELL JUNCTIONS IN AMPHIBIAN SKIN  

PubMed Central

Cell junctions have been investigated in the amphibian epidermis, a stratified squamous epithelium, and compared to those described previously in simple columnar epithelia of mammalian cavitary organs. In adult frogs and toads, and in larvae approaching metamorphosis, belts of membrane fusion or zonulae occludentes of considerable depth are regularly found between adjoining cells of the outermost layer of the stratum corneum, binding the cells together into a continuous, uninterrupted sheet. Another set of occluding zonules appears in the second cornified layer (when such a layer is present), and a third set usually occurs in the outermost layer of the stratum granulosum. Specialized elements described as "modified" and "composite" desmosomes are encountered along the lateral and basal aspects, respectively, of the cornified cells; ordinary desmosomes and maculae occludentes (i.e., spots of membrane fusion) are found in all other strata. The usual 200 A intercellular gap is generally maintained between the cells of the stratum germinativum at the basal ends of the intercellular spaces. Hence, the intercellular spaces of the epidermis form a largely continuous network, closed to the external medium and open to the dermal interstitia. The situation is comparable to that found in columnar epithelia, except that the intercellular spaces are much more extensive, and an extracellular subcompartment (or two) apparently exists in the stratum corneum and between the latter and the stratum granulosum. The last subcompartment is usually filled with a dense substance, probably derived from discharged secretory granules. The tripartite junctional complex characteristic of lumen-lining epithelia (i.e., a zonula occludens followed by a zonula adhaerens, and desmosome) is seen only in early larvae; in adults and in larvae approaching metamorphosis, the occluding zonule is followed directly by a series of modified desmosomes. Interpreted in the light of current physiological data, these findings suggest that the diffusion of water, ions, and small, water-soluble molecules is impeded along the intercellular spaces of the epidermis by zonulae occludentes while it is facilitated from cell to cell within the epidermis by zonulae and maculae occludentes. PMID:5859021

Farquhar, Marilyn G.; Palade, George E.

1965-01-01

197

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

198

Junction Plasmon-Induced Molecular Reorientation  

SciTech Connect

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

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

2013-10-17

199

Long Josephson junctions with multiband superconductors  

NASA Astrophysics Data System (ADS)

I present a study of collective modes and long Josephson junctions made of multiband superconductors with and without breaking of time-reversal symmetry. We discuss how the collective modes manifest themselves in vortices and the magnetic responses of such junctions. Supported by the Swedish Research council, the Knut and Alice Wallenberg Foundation through the Royal Swedish Academy of Sciences fellowship and by NSF CAREER Award No. DMR-0955902. Computational resources provided by NSC, Sweden.

Weston, Daniel; Babaev, Egor

2013-03-01

200

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

201

Paracellular Ion Channel at the Tight Junction  

PubMed Central

The tight junction of epithelial cells excludes macromolecules but allows permeation of ions. However, it is not clear whether this ion-conducting property is mediated by aqueous pores or by ion channels. To investigate the permeability properties of the tight junction, we have developed paracellular ion flux assays for four major extracellular ions, Na+, Cl?, Ca2+, and Mg2+. We found that the tight junction shares biophysical properties with conventional ion channels, including size and charge selectivity, dependency of permeability on ion concentration, competition between permeant molecules, anomalous mole-fraction effects, and sensitivity to pH. Our results support the hypothesis that discrete ion channels are present at the tight junction. Unlike conventional ion channels, which mediate ion transport across lipid bilayers, the tight junction channels must orient parallel to the plane of the plasma membranes to support paracellular ion movements. This new class of paracellular-tight junction channels (PTJC) facilitates the transport of ions between separate extracellular compartments. PMID:12609869

Tang, Vivian W.; Goodenough, Daniel A.

2003-01-01

202

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

203

Calcium-dependent dynamics of cadherin interactions at cell-cell junctions.  

PubMed

Cadherins play a key role in the dynamics of cell-cell contact formation and remodeling of junctions and tissues. Cadherin-cadherin interactions are gated by extracellular Ca(2+), which serves to rigidify the cadherin extracellular domains and promote trans junctional interactions. Here we describe the direct visualization and quantification of spatiotemporal dynamics of N-cadherin interactions across intercellular junctions in living cells using a genetically encodable FRET reporter system. Direct measurements of transjunctional cadherin interactions revealed a sudden, but partial, loss of homophilic interactions (? = 1.17 ± 0.06 s(-1)) upon chelation of extracellular Ca(2+). A cadherin mutant with reduced adhesive activity (W2A) exhibited a faster, more substantial loss of homophilic interactions (? = 0.86 ± 0.02 s(-1)), suggesting two types of native cadherin interactions--one that is rapidly modulated by changes in extracellular Ca(2+) and another with relatively stable adhesive activity that is Ca(2+) independent. The Ca(2+)-sensitive dynamics of cadherin interactions were transmitted to the cell interior where ?-catenin translocated to N-cadherin at the junction in both cells. These data indicate that cadherins can rapidly convey dynamic information about the extracellular environment to both cells that comprise a junction. PMID:21613566

Kim, Sally A; Tai, Chin-Yin; Mok, Lee-Peng; Mosser, Eric A; Schuman, Erin M

2011-06-14

204

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

205

Junction conditions at spacetime singularities  

E-print Network

A classical model for the extension of singular spacetime geometries across their singularities is presented. The regularization introduced by this model is based on the following observation. Among the geometries that satisfy Einstein's field equations there is a class of geometries, with certain singularities, where the components of the metric density and their partial derivatives remain finite in the limit where the singularity is approached. Here we exploit this regular behavior of the metric density and elevate its status to that of a fundamental variable -- from which the metric is constructed. We express Einstein's field equations as a set of equations for the metric density, and postulate junction conditions that the metric density satisfies at singularities. Using this model we extend certain geometries across their singularities. The following examples are discussed: radiation dominated Friedmann-Robertson-Walker Universe, Schwarzschild black hole, Reissner-Nordstr\\"{o}m black hole, and certain Kasner solutions. For all of the above mentioned examples we obtain a unique extension of the geometry beyond the singularity.

Eran Rosenthal

2010-11-21

206

Plasticity of button-like junctions in the endothelium of airway lymphatics in development and inflammation.  

PubMed

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

2012-06-01

207

Distributed Simulation of Real Tunnel Junction Effects in Multi-Junction Solar Cells  

NASA Astrophysics Data System (ADS)

In this paper, we present an improved 3D distributed model that considers real operation regimes in a tunnel junction. This advanced method is able to accurately simulate the high concentrations at which the current in the solar cell surpasses the peak current of the tunnel junction. Simulations of dual-junction solar cells were carried out with different light profiles and including chromatic aberration to show the capabilities of the model. Such simulations show that, under some circumstances, the solar cell short circuit current may be slightly higher than the tunnel junction peak current without showing the characteristic dip in the J-V curve. This behavior is caused by the lateral current spreading towards the dark regions, which occurs through the anode region of the tunnel junction.

Espinet, P.; García, I.; Rey-Stolle, I.; Algora, C.; Baudrit, M.

2010-10-01

208

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

PubMed Central

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

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

2014-01-01

209

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

210

Semiconductor Lasers Containing Quantum Wells in Junctions  

NASA Technical Reports Server (NTRS)

In a recent improvement upon In(x)Ga(1-x)As/InP semiconductor lasers of the bipolar cascade type, quantum wells are added to Esaki tunnel junctions, which are standard parts of such lasers. The energy depths and the geometric locations and thicknesses of the wells are tailored to exploit quantum tunneling such that, as described below, electrical resistances of junctions and concentrations of dopants can be reduced while laser performances can be improved. In(x)Ga(1-x)As/InP bipolar cascade lasers have been investigated as sources of near-infrared radiation (specifically, at wavelengths of about 980 and 1,550 nm) for photonic communication systems. The Esaki tunnel junctions in these lasers have been used to connect adjacent cascade stages and to enable transport of charge carriers between them. Typically, large concentrations of both n (electron-donor) and p (electron-acceptor) dopants have been necessary to impart low electrical resistances to Esaki tunnel junctions. Unfortunately, high doping contributes free-carrier absorption, thereby contributing to optical loss and thereby, further, degrading laser performance. In accordance with the present innovation, quantum wells are incorporated into the Esaki tunnel junctions so that the effective heights of barriers to quantum tunneling are reduced (see figure).

Yang, Rui Q.; Qiu, Yueming

2004-01-01

211

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

212

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

213

Real-Space Microscopic Electrical Imaging of n+-p Junction Beneath Front-Side Ag Contact of Multicrystalline Si Solar Cells  

SciTech Connect

We investigated the quality of the n+-p diffused junction beneath the front-side Ag contact of multicrystalline Si solar cells by characterizing the uniformities of electrostatic potential and doping concentration across the junction using the atomic force microscopy-based electrical imaging techniques of scanning Kelvin probe force microscopy and scanning capacitance microscopy. We found that Ag screen-printing metallization fired at the over-fire temperature significantly degrades the junction uniformity beneath the Ag contact grid, whereas metallization at the optimal- and under-fire temperatures does not cause degradation. Ag crystallites with widely distributed sizes were found at the Ag-grid/emitter-Si interface of the over-fired cell, which is associated with the junction damage beneath the Ag grid. Large crystallites protrude 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 junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent re-crystallization with incorporation of Ag and other impurities and with formation of crystallographic defects during quenching. The effect of this junction damage on solar cell performance is discussed.

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

2012-04-15

214

Synchronized switching in a josephson junction crystal.  

PubMed

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

Leib, Martin; Hartmann, Michael J

2014-06-01

215

Linear ac response of diffusive SNS junctions  

NASA Astrophysics Data System (ADS)

We explore the behavior of the ac admittance of superconductor-normal-metal-superconductor (SNS) junctions as the phase difference of the order parameters between the superconductors is varied. We find three characteristic regimes, defined by comparison of the driving frequency ? to the inelastic scattering rate ? and the Thouless energy ET of the junction (typically ???ET). Only in the first regime ??? does the usual picture of the kinetic inductance hold. We show that the ac admittance can be used to directly access some of the characteristic quantities of the SNS junctions, in particular the phase-dependent energy minigap and the typically phase-dependent inelastic scattering rate. Our results partially explain the recent measurements of the linear response properties of SNS superconducting quantum interference devices (SQUIDs) and predict a number of new effects.

Virtanen, Pauli; Bergeret, F. Sebastián; Cuevas, Juan Carlos; Heikkilä, Tero T.

2011-04-01

216

Isolation of mouse myocardial gap junctions  

PubMed Central

A new method is presented for the isolation of an enriched fraction of mouse myocardial gap junctions without the use of exogenous proteases. The junctions appear well preserved morphologically and similar to their appearance in situ. Contaminants of the preparation include fragments of the fascia adherens region of the intercalated disk. SDS polyacrylamide gel electrophoresis of the preparation reveals seven major bands with apparent mol wt of 28,000; 31,000; 33,500; 43,000; 47,000; 49,000; and 57,000. Only the bands at 38,000; 31,000; 33,500; and possibly the diffuse band at 47,000 copurify with the morphologically assayed gap junctions. Evidence is presented that the peptides at 43,000 and 57,000 are contained within the contaminating fascia adherens. PMID:7410477

1980-01-01

217

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

218

Characterization of discontinuous buffer junctions using pH indicators in capillary electrophoresis for protein preconcentration.  

PubMed

An effective sample preconcentration technique for proteins and peptides was recently developed using capillary electrophoresis (CE) with discontinuous buffers [C.A. Nesbitt, J.T.-M. Lo, K.K.-C. Yeung, J. Chromatogr. A 1073 (2005) 175]. Two buffers of different pH created a junction to trap the sample molecules at their isoelectric points and resulted in over 1000-fold preconcentration for myoglobin within 30 min. To study the formation of pH junctions in CE, a pH indicator, bromothymol blue, is used in this work to reveal the pH changes at the discontinuous buffer boundary. Bromothymol blue (BTB) exhibits a drastic change in its visible absorption spectrum (300-600 nm) going from the acidic to basic pH conditions, and is therefore ideal for visualizing the changes in pH at the junctions created by various buffer combinations. Preconcentration of myoglobin was performed in discontinuous buffers containing BTB. Major differences in the BTB absorption profiles were identified from buffer systems that differ significantly in preconcentration performance, which in turn, allowed for the identification of ideal buffers for sample preconcentration. Up to 2000-fold preconcentrations of myoglobin were achieved in the buffer systems studied in this work. In addition, the role of the electroosmotic flow (EOF) on the preconcentration performance was investigated. A low EOF was found to be desirable, as the pH junction could stay longer in the capillary for accumulation of proteins. The pH junction also displayed characteristics to resist bandbroadening. Potential laminar flow resulted from the mismatched residual EOFs under the two pH conditions within the discontinuous buffers appeared to have minimal effect on the preconcentration. In fact, external applied pressure can be used to control the migration of the pH junction without compromising the protein preconcentration. PMID:17022988

Jurcic, Kristina; Nesbitt, Chandra A; Yeung, Ken K-C

2006-11-17

219

Fundamental understanding of the physics and modeling of boron source/drain extension evolution during CMOS device fabrication  

NASA Astrophysics Data System (ADS)

Improvements in the integrated circuit performance over the past three decades have been mainly possible by the downward scaling of device dimensions. Device scaling requires that all lateral and vertical dimensions of the transistor be scaled. In the last decade, in order to continue conventional scaling of the source/drain junctions, the semiconductor industry has relied heavily on decreasing the implant energy, and also on minimizing the thermal budget of the activation anneal. With Transient Enhanced Diffusion less pronounced for low implant energies and sharper anneal temperature profiles, interactions of dopant atoms and point defects with surface films and interfaces are becoming of paramount importance in determining the concentrations of dopants and point defects, and therefore the resulting device structures. A nitride spacer with an underlying deposited TEOS oxide, that behaves as a convenient etch stop layer, is a popular choice for sidewall spacer in modern CMOS process flows. In this work the effect of the silicon nitride spacer process on the B profile in silicon and the related dose loss of B from the Si into the silicon dioxide has been investigated. This is reflected as a dramatic decrease in the junction depth. The influence of the nitride spacer chemistry on B dose loss from the Si has also been investigated. The different nitride chemistries result in different B dose loss. A new model that predicts B junction depths and dose loss during fabrication of ultra-shallow junctions has been developed. A study of the interactions of dopant atoms and silicon point defects with silicon oxide films during annealing for ultra-shallow junction formation has been included. A new method for activation of source/drain junctions by microwave annealing has been proposed.

Kohli, Puneet

220

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

221

Optimized THz emission from intrinsic Josephson junctions  

NASA Astrophysics Data System (ADS)

Nearly every wavelength from dc to x-rays significantly benefits today's society with a notable exception: the THz or sub-millimeter band. Applications in this range are widespread, penetrating fields ranging from national security to medicine, but remain largely under-utilized due to the difficulty of creating, manipulating, and detecting this type of radiation. Our research focus is THz source development using superconductive Josephson junctions to potentially address the lack of compact, efficient, and tunable source of continuous THz radiation. We review relevant applications for such a source and report an optimized design of a miniature THz emitter using single crystal intrinsic Josephson junctions.

Moody, Nathan A.; Boulaevskii, Lev N.; Pavlenko, Vitaly

2011-05-01

222

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

223

6. View northeast, junction of SR 141 and Rockland Road, ...  

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

6. View northeast, junction of SR 141 and Rockland Road, western estate wall and tree lines to right - A. I. Du Pont Estate, Junction of State Route 141 & Rockland Road, Wilmington, New Castle County, DE

224

8. Vidw southwest, junction of SR 141 and Rockland Road, ...  

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

8. Vidw southwest, junction of SR 141 and Rockland Road, northern estate wall and tree lines to left - A. I. Du Pont Estate, Junction of State Route 141 & Rockland Road, Wilmington, New Castle County, DE

225

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

226

Experimental Studies of Oxide Magnetic Tunnel Junctions and Graphene  

E-print Network

Studies of Oxide Magnetic Tunnel Junctions and Graphene AStudies of Oxide Magnetic Tunnel Junctions and Graphene byGraphene FET devices ..76 xvi Chapter I Manganite Electronic Band Structure and Magnetism I-1 Manganite Crystal Structure Transition metal oxides

Liu, Xinfei

2012-01-01

227

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

228

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

229

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

230

Stable semiconductor liquid junction cell with 9% solar to electrical conversion efficiency  

Microsoft Academic Search

The semiconductor liquid junction cell n-GaAs\\/0.8F K2Se2-1F KOH\\/C has been shown to deliver 9% photovoltaic power conversion efficiency in sunlight. Accelerated tests under 3100 K light sources of several solar intensities indicate very low photocorrosion currents and high output stability. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Keywords (in

K. C. Chang; A. Heller; B. Schwartz; S. Menezes; B. Miller

1977-01-01

231

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

Microsoft Academic Search

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

F. Sarubbi

2010-01-01

232

High voltage series connected tandem junction solar battery  

DOEpatents

A high voltage series connected tandem junction solar battery which comprises a plurality of strips of tandem junction solar cells of hydrogenated amorphous silicon having one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon, arranged in a tandem configuration, can have the same bandgap or differing bandgaps. The tandem junction strip solar cells are series connected to produce a solar battery of any desired voltage.

Hanak, Joseph J. (Lawrenceville, NJ)

1982-01-01

233

Heat conduction across molecular junctions between nanoparticles Samy Merabia,1,  

E-print Network

Heat conduction across molecular junctions between nanoparticles Samy Merabia,1, Jean-Louis Barrat 27, 2011) We investigate the problem of heat conduction across a molecular junction connecting two, a mini- mal thermal conductivity is required to convert heat in electric current; molecular junctions

Paris-Sud XI, Université de

234

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

235

Josephson current in mixed overlap/in-line long junctions  

NASA Astrophysics Data System (ADS)

The static configurations of the phase in a long Josephson junction are investigated by studying the phase space associated with the Static Perturbed Sine-Gordon Equation (SPSGE). Mixed overlap/in-line long Josephson junctions are considered. Analytical results concerning the dependence of the zero-field critical current on the junction length are reported.

Pagano, Sergio; Ruggiero, Berardo; Russo, Maurizio; Sarnelli, Ettore

1990-08-01

236

INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation  

E-print Network

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

237

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

238

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

PubMed

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

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

2014-08-27

239

Axial p-n-junctions in nanowires.  

PubMed

The charge distribution and potential profile of p-n-junctions in thin semiconductor nanowires (NWs) were analyzed. The characteristics of screening in one-dimensional systems result in a specific profile with large electric field at the boundary between the n- and p- regions, and long tails with a logarithmic drop in the potential and charge density. As a result of these tails, the junction properties depend sensitively on the geometry of external contacts and its capacity has an anomalously large value and frequency dispersion. In the presence of an external voltage, electrons and holes in the NWs can not be described by constant quasi-Fermi levels, due to small values of the average electric field, mobility, and lifetime of carriers. Thus, instead of the classical Sah-Noice-Shockley theory, the junction current-voltage characteristic was described by an alternative theory suitable for fast generation-recombination and slow diffusion-drift processes. For the non-uniform electric field in the junction, this theory predicts the forward branch of the characteristic to have a non-ideality factor ? several times larger than the values [Formula: see text] from classical theory. Such values of ? have been experimentally observed by a number of researchers, as well as in the present work. PMID:25656461

Fernandes, C; Shik, A; Byrne, K; Lynall, D; Blumin, M; Saveliev, I; Ruda, H E

2015-02-27

240

Polyphosphonium-based ion bipolar junction transistors.  

PubMed

Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e., ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2??m, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example, addressable drug-delivery devices. PMID:25553192

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

2014-11-01

241

TOPICAL REVIEW: Molecular transport junctions: vibrational effects  

Microsoft Academic Search

Transport of electrons in a single molecule junction is the simplest problem in the general subject area of molecular electronics. In the past few years, this area has been extended to probe beyond the simple tunnelling associated with large energy gaps between electrode Fermi level and molecular levels, to deal with smaller gaps, with near-resonance tunnelling and, particularly, with effects

Michael Galperin; Mark A. Ratner; Abraham Nitzan

2007-01-01

242

Spectroscopy of Capacitively-Coupled Junction Qubits  

Microsoft Academic Search

Capacitively-coupled Josephson junctions may allow fundamentally important observations of macroscopically entangled quantum states and the construction of quantum gates. We show how the quantum states and energy levels of this simple system may be effectively tuned and controlled by numerically computing the metastable states in the full, nonlinear Hamiltonian (our methods have broad applicability to realistic coupled qubit systems). Spectroscopic

Philip R. Johnson; Frederick W. Strauch; Alex J. Dragt; Roberto C. Ramos; Andrew J. Berkley; Huizhong Xu; Mark A. Gubrud; James R. Anderson; Christopher J. Lobb; Frederick C. Wellstood

2003-01-01

243

Miniaturized symmetrization optics for junction laser  

NASA Technical Reports Server (NTRS)

Miniaturized optics comprising transverse and lateral cylindrical lenses composed of millimeter-sized rods with diameters, indices-of-refraction and spacing such that substantially all the light emitted as an asymmetrical beam from the emitting junction of the laser is collected and translated to a symmetrical beam.

Hammer, Jacob M. (Inventor); Kaiser, Charlie J. (Inventor); Neil, Clyde C. (Inventor)

1982-01-01

244

Quantum effects in nanoscale Josephson junction circuits  

E-print Network

of the electromagnetic environment surrounding the junction has to be larger than the quantum resistance (RQ = h/4e2 6 of the electromagnetic environment. By applying a magnetic field perpendicular to the SQUID loops, the Josephson energy.45 k). In this work the high impedance environment is obtained by biasing the sample un- der test

Haviland, David

245

Costochondral junction osteomyelitis in 3 septic foals.  

PubMed

The costochondral junction constitutes a potential site of infection in septic foals and it could be favored by thoracic trauma. Standard radiographs and ultrasonography are useful tools for diagnosis of this condition and ultrasound-guided needle aspiration could permit the definitive confirmation of infection. PMID:22210943

Cesarini, Carla; Macieira, Susana; Girard, Christiane; Drolet, Richard; d'Anjou, Marc-André; Jean, Daniel

2011-07-01

246

Effects of hydration on molecular junction transport  

Microsoft Academic Search

The study of charge transport through increasingly complex small molecules will benefit from a detailed understanding of how contaminants from the environment affect molecular conduction. This should provide a clearer picture of the electronic characteristics of molecules by eliminating interference from adsorbed species. Here we use magnetically assembled microsphere junctions incorporating thiol monolayers to provide insight into changing electron transport

David P. Long; Jason L. Lazorcik; Brent A. Mantooth; Martin H. Moore; Mark A. Ratner; Alessandro Troisi; Yuxing Yao; Jacob W. Ciszek; James M. Tour; Ranganathan Shashidhar

2006-01-01

247

Tandem junction amorphous silicon solar cells  

DOEpatents

An amorphous silicon solar cell has an active body with two or a series of layers of hydrogenated amorphous silicon arranged in a tandem stacked configuration with one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon arranged in tandem configuration can have the same bandgap or differing bandgaps.

Hanak, Joseph J. (Lawrenceville, NJ)

1981-01-01

248

A novel Schottky junction back gate VDMOSFET  

Microsoft Academic Search

Using a Schottky barrier type back gate contact to minimize the body diode current of a conventional vertical power MOSFET is an attractive a lternative for device structures related to synchronous rectification power control. This approach is analyzed by device simulation emphasizing static and dynamic transport. The numerical results for steady state show that introducing an independent Schottky junction back

N. Yamashita; E.-S. Vera; T. Sakai; T. Yachi

1992-01-01

249

Graphite-graphene semiconductor junctions and magneto-dielectric coupling in Schottky diodes  

NASA Astrophysics Data System (ADS)

The goal of this dissertation is to incorporate graphite and graphene into today's semiconductor technology as a Schottky barrier diodes (metal/semiconductor junctions) that are widely used in metal semiconductor field effect transistors (MESFETs), high electron mobility transistors (HEMTs), high temperature and frequency devices, solar cells and sensors/detectors. The first part of the dissertation aims to give the reader a general idea about the physics at the metal-semiconductor junctions and essential theory background. The second chapter of the dissertation questions effects of temperature and magnetic field on the diode characteristics of Schottky junctions. In this chapter, we present observation of negative magnetocapacitance on GaAs:Si/Au junctions and fully equipped with the theory, we present a phenomenological explanation for the observed effect. In the third chapter, we for the first time introduce multi-layer-graphene as a metal (semimetal) electrode to form Schottky barriers on various technologically significant semiconductors such as Si, GaAs, SiC and GaN. Multi-layer-graphene/ semiconductor junctions not only display good current-voltage (I - V) and capacitance-voltage (C - V) characteristics but also are significant since the Schottky barrier height and characteristics are mainly governed by the interaction and bond formation at few layers on the metal and semiconductor interface. This automatically implies that the presented results also hold for graphene/semiconductor junctions. Chapter 4, takes the Schottky formation at the multi-layer-graphene(graphene)/ semiconductor junction to another level and aims to change the Fermi level of the metal electrode by intercalation with Bromine and tune the barrier height. Observed results are significant in MESFET technology since different barrier height are desired depending on the application. The remainder of the dissertation, focuses on the properties of graphite and graphene to have more understanding about the content presented in the previous chapters. Chapter 5, gives a brief theory background about graphite and graphene while Chapter 6 and Chapter 7 discuss electrical properties of graphite at high temperatures where it starts to decouple from each graphene layer and acts as bi-layer graphene and with bromine intercation where there is c-axis lattice constant expansion and each graphene plane becomes more isolated. Chapter 8, gives a detailed description about epitaxial graphene growth in SiC by joule annealing technique, and we end the chapter with future directions.

Tongay, Sefaattin

250

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

251

Cx43 in mesenchymal stem cells promotes angiogenesis of the infarcted heart independent of gap junctions.  

PubMed

Mesenchymal stem cells (MSCs) with elevated levels of connexin 43 (Cx43) have been shown to exhibit improved protection for ischemic hearts. However, it remains unclear whether Cx43 is involved in the paracrine actions of angiogenesis, the major mechanism of cell therapy. In the present study, an in vitro model with deprivation of oxygen and a murine myocardial infarction model with permanent ligation of the left anterior?descending (LAD) coronary artery were used to determine whether gap junctions in MSCs promote angiogenesis. It was observed that MSCs that overexpressed Cx43 (MSCs?Cx43), improve the cardiac function of infarcted myocardium as compared with control MSCs (MSCs?vector) and MSCs with Cx43 knocked down by small interfering RNA (MSCs?siCx43), accompanied with a reduction of infarct size and an increase in the vascular density and maturity. Increased levels of representative angiogenic factors [vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF)] were produced by MSCs?Cx43 compared with MSCs?siCx43 in vivo and in vitro. However, neither Cx43 formed gap junction specific inhibitor (Cx43 mimetic peptide) or gap junction opener (antiarrhythmic peptide) affected the production of VEGF and bFGF in MSCs under hypoxic stress. These data support the hypothesis that Cx43 in MSCs promotes angiogenesis in the infarcted heart, independent of gap junction formation. PMID:24481773

Wang, De-Guo; Zhang, Feng-Xiang; Chen, Ming-Long; Zhu, Hong-Jun; Yang, Bing; Cao, Ke-Jiang

2014-04-01

252

Coherent transmission of nodal Dirac fermions through a graphene-based superconducting double barrier junction  

NASA Astrophysics Data System (ADS)

Transport characteristics of relativistic electrons through graphene-based d-wave superconducting double barrier junction and ferromagnet/ d-wave superconductor/normal metal double junction have been investigated based on the Dirac-Bogoliubov-de Gennes equation. We have first presented the results of superconducting double barrier junction. In the subgap regime, both the crossed Andreev and nonlocal tunneling conductance all oscillate with the bias voltage due to the formation of Andreev bound states in the normal metal region. Moreover, the critical voltage beyond which the crossed Andreev conductance becomes to zero decreases with increasing value of superconducting pair potential ?. In the presence of the ferromagnetism, the MR through graphene-based ferromagnet/ d-wave superconductor/normal metal double junction has been investigated. It is shown that the MR increases from exchange splitting h 0=0 to h 0= E F (Fermi energy), and then it goes down. At h 0= E F, MR reaches its maximum 100. In contrast to the case of a single superconducting barrier, Andreev bound states also manifest itself in the zero bias MR, which result in a series of peaks except the maximum one at h 0= E F. Besides, the resonance peak of the MR can appear at certain bias voltage and structure parameter. Those phenomena mean that the coherent transmission can be tuned by superconducting pair potential, structure parameter, and external bias voltage, which benefits the spin-polarized electron device based on the graphene materials.

Bai, Chunxu; Wei, Ke-Wei; Yang, Gui; Yang, Yanling

2013-05-01

253

AlGaAs quantum-well solar cell junctions on beryllium telluride grown on silicon  

NASA Astrophysics Data System (ADS)

A bandgap combination of 1.7 eV and 1.1 eV offers the highest theoretical efficiency for a series-connected tandem-junction solar cell. The monolithic structure of aluminum gallium arsenide grown on silicon is a natural implementation, but has long-standing crystal-quality challenges such as lattice mismatch and island growth of AlGaAs. We address the growth issues by use of an interlayer of BeTe on silicon. AlGaAs grown on BeTe has a strong tendency for island formation, which is suppressed by low-temperature growth initiation. A barrier for electrical transport at the p-BeTe/p-AlGaAs interface is also reduced by low-temperature growth, and BeTe anneal under arsenic rather than tellurium flux. Al0.15Ga0.85As-GaAs multiple quantum-well p-i-n junction structures were grown on both Si/BeTe and GaAs substrates for electrical characterization. In preliminary results, the short-circuit photocurrent JSC and open-circuit voltage VOC is lower in the Si/BeTe based junction than the GaAs based junction, with about twice the fractional reduction of VOC than of JSC. A graded-bandgap emitter structure with different n+GaAs top contact layer thicknesses exhibited JSC reduction less than 15%.

Clark, Kevin; Maldonado, Eduardo; Amir, Fatima; Bate, Robert; Kirk, Wiley

2007-03-01

254

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

255

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

256

Physiological and physiopathological aspects of connexins and communicating gap junctions in spermatogenesis  

PubMed Central

Spermatogenesis is a highly regulated process of germ cell proliferation and differentiation, starting from spermatogonia to spermatocytes and giving rise to spermatids, the future spermatozoa. In addition to endocrine regulation, testicular cell–cell interactions are essential for spermatogenesis. This precise control is mediated through paracrine/autocrine pathways, direct intercellular contacts and through intercellular communication channels, consisting of gap junctions and their constitutive proteins, the connexins. Gap junctions are localized between adjacent Leydig cells, between Sertoli cells and between Sertoli cells and specific germ cells. This review focuses on the distribution of connexins within the seminiferous epithelium, their participation in gap junction channel formation, the control of their expression and the physiological relevance of these junctions in both the Sertoli–Sertoli cell functional synchronization and the Sertoli–germ cell dialogue. In this review, we also discuss the potential implication of disrupted connexin in testis cancer, since impaired expression of connexin has been described as a typical feature of tumoral proliferation. PMID:20403873

Pointis, Georges; Gilleron, Jérome; Carette, Diane; Segretain, Dominique

2010-01-01

257

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

PubMed

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

2013-06-01

258

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

259

The Crystal Structures of Psoralen Cross-linked DNAs: Drug-dependent Formation of  

E-print Network

#12;The Crystal Structures of Psoralen Cross-linked DNAs: Drug-dependent Formation of Holliday-trimethylpsoralen (HMT). The HMT-adduct of d(CCGCTAGCGG) forms a psoralen-induced Holliday junction, showing. The psoralen cross-link de®nes the intramolecular interactions of the drug-induced junction, while the sequence

Eichman, Brandt F.

260

Microwave detector response of the Josephson junction arrays  

SciTech Connect

This paper reports on microwave detector response {eta} for three types of superconducting structures:single edge-type Josephson junction, array of series connected junctions and array of RF series and DC parallel connected junctions investigated in the frequency range 35-120 GHz. Experimental dependence of {eta} vs biasing voltage is mainly determined by the interaction of junctions in array. The Selective response, that means narrow linewidth of Josephson radiation, has been observed for third type of superconducting structures in small magnetic field changing the phase shift between near placed junctions. These arrays have the advantage in coupling with the external microwave system.

Ovsyannikov, G.A.; Babayan, G.E. (Inst. of Radio Engineering and Electronics, Academy of Sciences, Moscow 103907 (SU)); Laptev, V.N.; Makhov, V.I. (Research Inst. of Physical Problems, Moscow 103460 (SU))

1991-03-01

261

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

PubMed Central

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

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

2010-01-01

262

Human cardiac gap junctions: isolation, ultrastructure, and protein composition.  

PubMed

Recent experiments from our laboratory have shown that the ultrastructure and protein composition of gap junctions isolated from rat ventricles are tissue specific, i.e., markedly different from gap junctions of liver and lens. The differences include a cytoplasmic surface component characteristic for cardiac gap junctions; this component can be visualized by two ultrastructural techniques: as a fuzzy layer in electron micrographs of thin-sectioned junctional pellets and as cytoplasmic surface particles in deep-etched freeze-fractured junctions. The component corresponds to a Mr 17,500 cytoplasmic surface domain of each of the six (Mr 47,000) rat heart gap junctional channel protein subunits that make up the gap junctional channel hexamer known as a connexon. The cytoplasmic surface component is localized at the carboxy-terminal of the subunit. Within the cytoplasmic surface component, rat cardiac gap junctions are cross-linked by disulfide linkages between subunits of the same connexon and between subunits of adjacent connexons. By contrast, the Mr 28,000 liver gap junctional subunit lacks a comparably large cytoplasmic surface component, cytoplasmic surface fuzz, cytoplasmic surface particles, and intra- and interconnexon disulfide linkages. Most of these unique characteristics of cardiac gap junctions were discovered in junctions isolated from rat ventricles. Unlike liver and lens gap junctions, cardiac gap junctions from humans, non-human primates, or other large mammals have not previously been isolated and characterized. Here we report the isolation of unproteolyzed gap junctions from the ventricle of a 24 year-old man with advanced cardiomyopathy whose heart was removed for replacement by a transplanted heart.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3573042

Manjunath, C K; Goings, G E; Page, E

1987-02-01

263

New advances in on-line sample preconcentration by capillary electrophoresis using dynamic pH junction.  

PubMed

The small injection volumes and narrow dimensions characteristic of microseparation techniques place constraints on concentration sensitivity that is required for trace chemical analyses. On-line sample preconcentration techniques using dynamic pH junction and its variants have emerged as simple yet effective strategies for enhancing concentration sensitivity of weakly ionic species by capillary electrophoresis (CE). Dynamic pH junction offers a convenient format for electrokinetic focusing of dilute sample plugs directly in-capillary for improved detection without off-line sample pretreatment. In this report, we highlight new advances in dynamic pH junction which have been reported to enhance method performance while discussing challenges for future research. PMID:19082065

Ptolemy, Adam S; Britz-McKibbin, Philip

2008-12-01

264

Electron Holography Characterization of Shallow Junction Fabricated By Diffusion-less Process for Sub-30 nm Gate-Length MOSFETs  

SciTech Connect

Cross-sectional electron holography was used for two-dimensional potential mapping of source/drain extensions (SDEs) in scaled MOSFETs fabricated using state-of-the-art junction formation technology. First, we show that specimen-preparation artifacts, which have prevented detailed examinations of scaled SDEs, are significantly reduced by using low-energy backside Ar{sup +} milling. Next, we demonstrate that electron holography clearly reveals very shallow (10-nm-deep) SDE junction profiles. We also show that the experimental examinations, in conjunction with doping-process simulations, allow examinations of how dopant distribution, such as junction depth and abruptness, affect the potential distribution in planar-bulk MOSFETs approaching the scaling limit.

Ikarashi, Nobuyuki; Toda, Akio [Device Platforms Research Laboratories, NEC Corporation, 1120 Shimokuzawa, Sagamihara, 229-1198 (Japan); Uejima, Kazuya; Fukai, Toshinori; Hane, Masami [NEC Electronics Corporation 1120 Shimokuzawa, Sagamihara, 229-1198 (Japan); Ikezawa, Takeo [NEC Informatic Systems Corporation, 1120 Shimokuzawa, Sagamihara, 229-1198 (Japan)

2008-11-03

265

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

SciTech Connect

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

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

2008-07-15

266

Direct evidences of filamentary resistive switching in Pt/Nb-doped SrTiO3 junctions  

NASA Astrophysics Data System (ADS)

The first concerned question on the fundamental physics of the resistive switching (RS) effect in metal/Nb-doped SrTiO3 junctions is whether the RS does take place at the whole interface or at some local regions of the interface. Even though several investigations provide the clues of the filamentary nature of the RS, direct evidences are still required. Moreover, there is obvious inconsistency between the possible filamentary feature and the observed capacitance-voltage (C-V) hysteresis loops. Here, we report direct evidences of a filamentary RS effect in Pt/Nb-doped SrTiO3 junctions. The virgin Pt/NSTO junctions show an initial RS effect. The current-voltage (I-V) characteristic of the initial RS and the C-V characteristic in the virgin junctions are interpreted by using the theory of metal/semiconductor contacts. The correspondence between the initial RS and the C-V hysteresis loops is also discussed. The most important is that an electroforming process is observed at a large forward voltage, which is a direct indication of the formation of conductive filaments across the Pt/NSTO interface. Following the electroforming, the Pt/NSTO junctions exhibit a filamentary RS effect. The I-V characteristic of the filamentary RS deviates from the theoretical prediction of metal/semiconductor interfaces. However, the C-V characteristic is almost the same as that of the virgin junctions. This demonstrates that the conductive filaments are formed at local regions of the Pt/NSTO interface and a majority of the interface remains invariant. The results clearly show that a filamentary RS effect occurs in the Pt/NSTO junctions and that the observed C-V hysteresis loops are not correlated to the filamentary RS.

Yang, M.; Ren, L. Z.; Wang, Y. J.; Yu, F. M.; Meng, M.; Zhou, W. Q.; Wu, S. X.; Li, S. W.

2014-04-01

267

Gap junctional communication between murine macrophages and intestinal epithelial cell lines.  

PubMed

In intestinal inflammation, inflammatory cells infiltrate the submucosa and are found juxtaposed to intestinal epithelial cell (IEC) basolateral membranes and may directly regulate IEC function. In this study we determined whether macrophage (M phi), P388D1 and J774A.1, are coupled by gap junctions to IEC lines, Mode-K and IEC6. Using flow cytometric analysis, we show bi-directional transfer of the fluorescent dye, calcein (700 Da) between IEC and M phi resulting in a 3.5-20-fold increase in recipient cell fluorescence. Homocellular and heterocellular dye transfer between M phi and/or IEC was detected in cocultures of P388D1, J774A.1, Mode-K, IEC6 and CMT93. However, transfer between P388D1 and Mode-K was asymmetrical in that transfer from P388D1 to Mode-K was always more efficient than transfer from Mode-K to P388D1. Dye transfer was strictly dependent on IEC-M phi adhesion which in turn was dependent on the polarity of IEC adhesion molecule expression. Both calcein dye transfer and adhesion were inhibited by the addition of heptanol to cocultures. Furthermore we demonstrate both IEC homocellular, and M phi-IEC heterocellular propagation of calcium waves in response to mechanical stimulation, typical of gap junctional communication. Finally, areas of close membrane apposition were seen in electron micrographs of IEC-M phi cocultures, suggestive of gap junction formation. These data indicate that IEC and M phi are coupled by gap junctions suggesting that gap junctional communication may provide a means by which inflammatory cells might regulate IEC function. PMID:9791725

Martin, C A; Homaidan, F R; Palaia, T; Burakoff, R; el-Sabban, M E

1998-09-01

268

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

269

Tight junction physiology of pleural mesothelium  

PubMed Central

Pleura consists of visceral and parietal cell layers, producing a fluid, which is necessary for lubrication of the pleural space. Function of both mesothelial cell layers is necessary for the regulation of a constant pleural fluid volume and composition to facilitate lung movement during breathing. Recent studies have demonstrated that pleural mesothelial cells show a distinct expression pattern of tight junction proteins which are known to ubiquitously determine paracellular permeability. Most tight junction proteins provide a sealing function to epithelia, but some have been shown to have a paracellular channel function or ambiguous properties. Here we provide an in-depth review of the current knowledge concerning specific functional contribution of these proteins determining transport and barrier function of pleural mesothelium. PMID:25009499

Markov, Alexander G.; Amasheh, Salah

2014-01-01

270

Heat flow in nonlinear molecular junctions  

E-print Network

We investigate the heat conduction properties of molecular junctions comprising anharmonic interactions. We find that nonlinear interactions can lead to novel phenomena: it negative differential thermal conductance and heat rectification. Based on analytically solvable models we derive an expression for the heat current that clearly reflects the interplay between anharmonic interactions, strengths of coupling to the thermal reservoirs, and junction asymmetry. This expression indicates that negative differential thermal conductance shows up when the molecule is strongly coupled to the thermal baths, even in the absence of internal molecular nonlinearities. In contrast, diode like behavior is expected for a highly anharmonic molecule with an inherent structural asymmetry. Anharmonic interactions are also necessary for manifesting Fourier type transport. We briefly present an extension of our model system that can lead to this behavior.

Dvira Segal

2005-12-22

271

LRP4 is critical for neuromuscular junction maintenance.  

PubMed

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

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

2014-10-15

272

Morphological and functional characteristics of human gingival junctional epithelium  

PubMed Central

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

2014-01-01

273

Reproducible step-edge junction SQUIDs  

Microsoft Academic Search

High-Tc superconducting YBCO SQUIDs have been developed based on step-edge junctions. The step-edges were fabricated by using electron-beam lithography and Ar-ion milling on SrTiO3 substrates. The V(?) peak-to-peak voltage is around 10 ?V, and the IcRn product is 150 ?V at 77 K. The SQUIDs prepared on the same substrate show reproducible parameters within 30%. At 77 K the noise

Y. Q. Shen; Z. J. Sun; R. Kromann; T. Holst; P. Vase; T. Freltoft

1995-01-01

274

Josephson Junctions Help Measure Resonance And Dispersion  

NASA Technical Reports Server (NTRS)

Electrical characteristics of superconducting microstrip transmission lines measured at millimeter and submillimeter wavelengths. Submicron Josephson (super-conductor/insulator/superconductor) junctions used as both voltage-controlled oscillators and detectors to measure frequencies (in range of hundreds of gigahertz) of high-order resonant electromagnetic modes of superconducting microstrip transmission-line resonators. This oscillator/detector approach similar to vacuum-tube grid dip meters and transistor dip meters used to probe resonances at much lower frequencies.

Javadi, Hamid H. S.; Mcgrath, William R.; Bumble, Bruce; Leduc, Henry G.

1994-01-01

275

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

PubMed

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

Dong, Gangqiang; Liu, Fengzhen; Liu, Jing; Zhang, Hailong; Zhu, Meifang

2013-01-01

276

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

277

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

278

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

PubMed

In higher vertebrates, the primordium of the nervous system, the neural tube, is shaped along the rostrocaudal axis through two consecutive, radically different processes referred to as primary and secondary neurulation. Failures in neurulation lead to severe anomalies of the nervous system, called neural tube defects (NTDs), which are among the most common congenital malformations in humans. Mechanisms causing NTDs in humans remain ill-defined. Of particular interest, the thoracolumbar region, which encompasses many NTD cases in the spine, corresponds to the junction between primary and secondary neurulations. Elucidating which developmental processes operate during neurulation in this region is therefore pivotal to unraveling the etiology of NTDs. Here, using the chick embryo as a model, we show that, at the junction, the neural tube is elaborated by a unique developmental program involving concerted movements of elevation and folding combined with local cell ingression and accretion. This process ensures the topological continuity between the primary and secondary neural tubes while supplying all neural progenitors of both the junctional and secondary neural tubes. Because it is distinct from the other neurulation events, we term this phenomenon junctional neurulation. Moreover, the planar-cell-polarity member, Prickle-1, is recruited specifically during junctional neurulation and its misexpression within a limited time period suffices to cause anomalies that phenocopy lower spine NTDs in human. Our study thus provides a molecular and cellular basis for understanding the causality of NTD prevalence in humans and ascribes to Prickle-1 a critical role in lower spinal cord formation. PMID:25253865

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

2014-09-24

279

Fermi edge singularity in a tunnel junction  

NASA Astrophysics Data System (ADS)

We present results on the non-equilibrium Fermi edge singularity (FES) problem in tunnel junctions. The FES, which is present in a Fermi gas subject to any sudden change of potential, manifests itself in the final state many body interaction between the electrons in the leads [1]. We establish a connection between the FES problem in a tunnel junction and the Full Counting Statistics (FCS) for the device [2]. We find that the exact profile of the changing potential (or the profile for the barrier opening and closing in the tunnel junction case) strongly affects the overlap between the initial and final state of the Fermi gas. We factorize the contribution to the FES into two approximately independent terms: one is connected with the short time opening process while the other is concerned with the long time asymptotic effect, namely the Anderson orthogonality catastrophe. We consider applications to a localized level coupled through a tunnel barrier to a 1D lead driven out of equilibrium [3]. References: [1] G. Mahan, Phys. Rev. 163, 1612 (1967); P. Nozieres and C. T. De Dominicis, Phys. Rev. 178, 1079 (1969); P. Anderson, Phys. Rev. Lett. 18, 1049 (1967) [2] J. Zhang, Y. Sherkunov, N. d'Ambrumenil, and B. Muzykantskii, ArXiv:0909.3427 [3] D. Abanin and L. Levitov, Phys. Rev. Lett. 94, 186803 (2005)

Zhang, Jin; Sherkunov, Yury; D'Ambrumenil, Nicholas; Muzykantskii, Boris

2010-03-01

280

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.

281

Acetylcholinesterase Clustering at the Neuromuscular Junction Involves Perlecan and Dystroglycan  

PubMed Central

Formation of the synaptic basal lamina at vertebrate neuromuscular junction involves the accumulation of numerous specialized extracellular matrix molecules including a specific form of acetylcholinesterase (AChE), the collagenic-tailed form. The mechanisms responsible for its localization at sites of nerve– muscle contact are not well understood. To understand synaptic AChE localization, we synthesized a fluorescent conjugate of fasciculin 2, a snake ?-neurotoxin that tightly binds to the catalytic subunit. Prelabeling AChE on the surface of Xenopus muscle cells revealed that preexisting AChE molecules could be recruited to form clusters that colocalize with acetylcholine receptors at sites of nerve–muscle contact. Likewise, purified avian AChE with collagen-like tail, when transplanted to Xenopus muscle cells before the addition of nerves, also accumulated at sites of nerve–muscle contact. Using exogenous avian AChE as a marker, we show that the collagenic-tailed form of the enzyme binds to the heparan-sulfate proteoglycan perlecan, which in turn binds to the dystroglycan complex through ?-dystroglycan. Therefore, the dystroglycan–perlecan complex serves as a cell surface acceptor for AChE, enabling it to be clustered at the synapse by lateral migration within the plane of the membrane. A similar mechanism may underlie the initial formation of all specialized basal lamina interposed between other cell types. PMID:10330416

Peng, H. Benjamin; Xie, Hongbo; Rossi, Susanna G.; Rotundo, Richard L.

1999-01-01

282

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

PubMed

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

Desforges, Bénédicte; Curmi, Patrick A; Bounedjah, Ouissame; Nakib, Samir; Hamon, Loic; De Bandt, Jean-Pascal; Pastré, David

2013-05-01

283

Enhanced photocatalytic performance of porous TiO2 nanobelts with phase junctions  

NASA Astrophysics Data System (ADS)

Porous TiO2 nanobelts with rutile/anatase phase junctions are successfully prepared through a hydrothermal route and ion exchange process. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were conducted to characterize the products. The photocatalytic performance of the porous nanobelts was evaluated by measuring the degradation of methyl blue under UV light irradiation. The photocatalytic activity of the porous nanobelts is much superior to that of P-25 and pristine non-porous nanobelts. The excellent photocatalytic of porous nanobelts can be attributed to pores which enhanced ability in UV-light harvesting. What's more, the existence of rutile/anatase phase junction is favorable for the formation and separation of the hole-electron pair, resulting in a reduced electron-hole recombination.

Pang, Lai-xue; Wang, Xiao-ying; Tang, Xin-de

2015-01-01

284

Effect of ion-milled barriers on electron transport in micrometer-sized tunnel junctions  

NASA Astrophysics Data System (ADS)

We studied the electron transport properties of micrometre-sized all-Al tunnel junctions (TJs) between 2 and 300 K, in which the AlOx layer grown by O2 plasma was moderately Ar-ion-milled prior to top electrode deposition. In contrast to the direct tunnelling in the TJs whose barriers are intact (not ion-milled), the zero-bias conductances and the current-voltage characteristics of the TJs as processed are found to be best described by the fluctuation-induced tunnelling conduction mechanism. This observation indicates the formation of nanoscopic incomplete pinholes in the AlOx layer, owing to large junction-barrier interfacial roughness introduced by the ion-milling process. Topographical features revealed by the cross-sectional transmission electron microscopy imaging of the TJ stack conform to this result. This study is of relevance to cases in which ion-milling techniques are applied in tailoring the TJ properties.

Lee, Yen-Chi; Lin, Yong-Han; Wu, Jong-Ching; Lin, Juhn-Jong

2014-03-01

285

RESEARCH PAPER Effect of geometry on droplet formation in the squeezing regime  

E-print Network

, particularly using co-flowing fluids (Umbanhowar et al. 2000; Cramer et al. 2004), passing dissimilar fluids through an orifice (Anna et al. 2003; Garstecki 2005) and droplet formation at T-junctions (Thorsen et al

Gupta, Amit

286

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

287

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

288

The critical power to maintain thermally stable molecular junctions.  

PubMed

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 10(9)?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. PMID:25005801

Wang, Yanlei; Xu, Zhiping

2014-01-01

289

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

290

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

291

Cell junctions in the subcommissural organ of the rabbit as revealed by use of ruthenium red  

Microsoft Academic Search

Tight junctions were found in the apical junctional complex of the adult rabbit subcommissural organ (SCO) in addition to zonulae adhaerentes and gap junctions of typical ependymal cells. Ventricular perfusion of ruthenium red before fixation was found to give excellent results for distinguishing between gap and tight junctions at the ependymal surface. The implication of tight junctions as a mechanical

Judith E. Kimble; S. C. Sørensen; K. Møllgaard

1973-01-01

292

Quantum dynamics of ultrasmall tunnel junctions: Real-time analysis  

Microsoft Academic Search

We present a real-time path-integral analysis of the quantum dynamics of an ultrasmall tunnel junction interacting with an arbitrary external impedance. For a normal junction, we derive a quasiclassical Langevin equation for the phase variable and calculate the I-V curve beyond perturbation theory for the junction conductance. In the superconducting case, we develop a nonperturbative calculation of the time-dependent expectation

D. S. Golubev; A. D. Zaikin

1992-01-01

293

Inelastic electron tunneling spectroscopy of molecular transport junctions  

NASA Astrophysics Data System (ADS)

Inelastic electron tunneling spectroscopy (IETS) has become a premier analytical tool in the investigation of nanoscale and molecular junctions. The IETS spectrum provides invaluable information about the structure, bonding, and orientation of component molecules in the junctions. One of the major advantages of IETS is its sensitivity and resolution at the level of single molecules. This review discusses how IETS is used to study molecular transport junctions and presents an overview of recent experimental studies.

Song, Hyunwook; Lee, Takhee; Reed, Mark

2014-05-01

294

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

295

Uniform Silicon p-n Junctions. I. Broad Area Breakdown  

Microsoft Academic Search

Small area silicon p-n junctions have been made which are free from exposed edges and dislocations passing through the space-charge region. It is believed that the space-charge regions of these junctions more closely resemble plane parallel geometries than any studied similarly hitherto. The avalanche breakdown phenomena in these uniform junctions are shown to be drastically different from those occuring in

R. L. Batdorf; A. G. Chynoweth; G. C. Dacey; P. W. Foy

1960-01-01

296

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

297

The 'depletion layer' of amorphous p-n junctions  

NASA Technical Reports Server (NTRS)

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

Von Roos, O.

1981-01-01

298

Image-soliton method applied to finite multiple tunnel junctions  

NASA Astrophysics Data System (ADS)

We show that the simple and physically intuitive method of soliton images can be used not only for a semi-infinite multiple tunnel junction (MTJ) array of identical junction capacitances C and stray capacitances C0, but is also applicable to both homogenous and inhomogenous MTJ's of a finite number of junctions. In the latter, a junction capacitance C'?C is replaced by a homogenous chain of equivalent length, thereby extending the method to important circuits relying on inhomogenous MTJ's, such as the multijunction trap and the multijunction turnstile.

Jalil, M. B. A.; Wagner, M.

1999-02-01

299

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

300

Terahertz magnetoplasmon energy concentration and splitting in Graphene PN Junctions.  

PubMed

Terahertz plasmons and magnetoplasmons propagating along electrically and chemically doped graphene p-n junctions are investigated. It is shown that such junctions support non-reciprocal magnetoplasmonic modes which get concentrated at the middle of the junction in one direction and split away from the middle of the junction in the other direction under the application of an external static magnetic field. This phenomenon follows from the combined effects of circular birefringence and carrier density non-uniformity. It can be exploited for the realization of plasmonic isolators. PMID:24150377

Chamanara, Nima; Sounas, Dimitrios; Szkopek, Thomas; Caloz, Christophe

2013-10-21

301

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

302

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.

303

p-n Junction Heterostructure Device Physics Model of a Four Junction Melissa J. Griggs*, Brendan M. Kayes, and Harry A. Atwater  

E-print Network

p-n Junction Heterostructure Device Physics Model of a Four Junction Solar Cell Melissa J. Griggs-n junction device physics model for GaInP/GaAs/GaInAsP/GaInAs four junction solar cells. The model employs characteristics of the cell model include: free carrier absorption, temperature and doping effects on carrier

Atwater, Harry

304

Dual Regulation of Endothelial Junctional Permeability  

NSDL National Science Digital Library

The endothelial monolayer maintains tissue fluid homeostasis by restricting transudation of fluid from intravascular space to underlying tissue. This Review, with two figures and 107 references, describes how proinflammatory stimuli regulate endothelial barrier function. The focus is on G protein–coupled receptor (GPCR)–mediated signaling events and how these signals control adherens junction integrity and thereby endothelial barrier function. We discuss the functional antagonism between thrombin and sphingosine-1-phosphate in generating signaling cascades that lead to barrier dysfunction or enhancement. Cross-talk between these signaling pathways plays a key role in mediating the endothelial barrier set point.

Yulia A. Komarova (Chicago; University of Illinois College of Medicine REV)

2007-11-13

305

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

306

Non-relativistic Josephson Junction from Holography  

E-print Network

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; Wang, Yong-Qiang; Zhang, Hai-Qing

2014-01-01

307

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

308

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

309

Complex Dynamics of Single Josephson Junctions and Josephson-Junction Arrays  

NASA Astrophysics Data System (ADS)

I measured current-voltage (I-V) characteristics of externally shunted Josephson tunnel junctions (Nb/Al _2O_3/Nb) where the external shunts have non-zero inductance. At low temperatures (T < 6.6 K), I observe standard I-V curves, but as temperature is increased above 6.6 K, I observe an anomaly in the I -V curves. I attribute this anomaly to the non-zero inductance in the shunt loop. Numerical simulations which properly take into account the effect of inductance show that the dynamics in the anomalous region of the I-V curve are dominated by subharmonic relaxation oscillations. I use a load-line analysis model to study the transition between the relaxation oscillations and the Josephson oscillations. The analysis is in good agreement with my data. The analysis further predicts, and my data confirm, that in order for the relaxation oscillations to occur it is necessary to have beta_{C} = 2pi I_{c} R_{s}^2 C/Phi_{0} < (4/pi) ^2, regardless of the value of the inductance. I carried out an extensive numerical study of the resistively-capacitively-inductively shunted junction (RCLSJ) model. Even though I considered only the case with dc drive, the dynamics were extremely rich and complex. In addition to the ac Josephson oscillations and relaxation oscillations, I saw chaotic solutions in some regions of the parameter space. I also found long chaotic transients which precede periodic attractors in a wide range of parameters. At low inductance, I observed period doubling as well as intermittency route to chaos. Chaotic transients are generally observed at relatively high inductance values. I also studied the effect of thermal Johnson noise on the dynamics. I discuss the implications of my numerical results for real Josephson junction experiments. I numerically studied phase-locking in two-dimensional (2D) arrays of Josephson junctions. In conventional 2D arrays biased with dc current in the horizontal (X) direction. the phase locked solution is only possible in arrays with no disorder. In the presence of disorder in the junction critical currents, I see vertical (Y) columns of phase locked clusters form in the array with no inter-column locking. As an extension, I introduced a new design which I call XY-biased array, where the array is biased in both X and Y directions. In XY-biased arrays I found a novel phase locked dynamical state, where all junction voltages are strictly dc while the currents oscillate. The new dynamical state is stable against experimentally achievable disorder in the junction critical currents.

Whan, Chagarn Barter

1995-01-01

310

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

311

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...

312

77 FR 10618 - Eric Temple-Control Exemption-Portland Vancouver Junction Railroad, LLC  

Federal Register 2010, 2011, 2012, 2013, 2014

...Temple--Control Exemption--Portland Vancouver Junction Railroad, LLC Eric Temple...to acquire direct control of Portland Vancouver Junction Railroad, LLC (PVJR), a...Cent. Wash. R.R. and Portland Vancouver Junction R.R.--Corporate...

2012-02-22

313

Switching and Rectification in Carbon-Nanotube Junctions  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

314

The three-way junction DNAzyme based probe for label-free colorimetric detection of DNA.  

PubMed

A novel three-way junction DNAzyme based probe has been designed for the colorimetric sensing of target DNA. Specifically, a DNAzyme-linked hairpin DNA is used as a signal probe. In the presence of target DNA, the signal probe, assistant probe and target DNA can hybridize with each other, resulting in the formation of a three-way junction DNA. At the same time, the signal probe is opened and the DNAzyme sequence in the signal probe is dehybridized. Subsequently, in the presence of hemin, the DNAzyme sequence forms a G-quadruplex-hemin complex, which catalyzes oxidation of 2, 2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) by H(2)O(2) to the colored ABTS(.-)radical. The significant color changes can be distinguished visually. By the combination of the hairpin probe and the three-way junction DNA probe, the proposed sensor exhibits high recognition property for single-nucleotide polymorphisms (SNPs). This sensor allows the detection of target DNA at a concentration as low as 0.25 nmol L(-1). The proposed sensor is easy to fabricate, which avoids the tedious and expensive labeling procedures, and exhibits high selectivity against single-base mismatched DNA. PMID:23017688

Tang, Shurong; Tong, Ping; Li, Heng; Gu, Fang; Zhang, Lan

2013-03-15

315

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

PubMed

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

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

2008-07-01

316

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

317

Novel pharmacologic targeting of tight junctions and focal adhesions in prostate cancer cells.  

PubMed

Cancer cell resistance to anoikis driven by aberrant signaling sustained by the tumor microenvironment confers high invasive potential and therapeutic resistance. We recently generated a novel lead quinazoline-based Doxazosin® derivative, DZ-50, which impairs tumor growth and metastasis via anoikis. Genome-wide analysis in the human prostate cancer cell line DU-145 identified primary downregulated targets of DZ-50, including genes involved in focal adhesion integrity (fibronectin, integrin-?6 and talin), tight junction formation (claudin-11) as well as insulin growth factor binding protein 3 (IGFBP-3) and the angiogenesis modulator thrombospondin 1 (TSP-1). Confocal microscopy demonstrated structural disruption of both focal adhesions and tight junctions by the downregulation of these gene targets, resulting in decreased cell survival, migration and adhesion to extracellular matrix (ECM) components in two androgen-independent human prostate cancer cell lines, PC-3 and DU-145. Stabilization of cell-ECM interactions by overexpression of talin-1 and/or exposing cells to a fibronectin-rich environment mitigated the effect of DZ-50. Loss of expression of the intracellular focal adhesion signaling effectors talin-1 and integrin linked kinase (ILK) sensitized human prostate cancer to anoikis. Our findings suggest that DZ-50 exerts its antitumor effect by targeting the key functional intercellular interactions, focal adhesions and tight junctions, supporting the therapeutic significance of this agent for the treatment of advanced prostate cancer. PMID:24497940

Hensley, Patrick J; Desiniotis, Andreas; Wang, Chi; Stromberg, Arnold; Chen, Ching-Shih; Kyprianou, Natasha

2014-01-01

318

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

319

ARIA is concentrated in the synaptic basal lamina of the developing chick neuromuscular junction  

PubMed Central

ARIA is a member of a family of polypeptide growth and differentiation factors that also includes glial growth factor (GGF), neu differentiation factor, and heregulin. ARIA mRNA is expressed in all cholinergic neurons of the central nervous systems of rats and chicks, including spinal cord motor neurons. In vitro, ARIA elevates the rate of acetylcholine receptor incorporation into the plasma membrane of primary cultures of chick myotubes. To study whether ARIA may regulate the synthesis of junctional synaptic acetylcholine receptors in chick embryos, we have developed riboprobes and polyclonal antibody reagents that recognize isoforms of ARIA that include an amino-terminal immunoglobulin C2 domain and examined the expression and distribution of ARIA in motor neurons and at the neuromuscular junction. We detected significant ARIA mRNA expression in motor neurons as early as embryonic day 5, around the time that motor axons are making initial synaptic contacts with their target muscle cells. In older embryos and postnatal animals, we found ARIA protein concentrated in the synaptic cleft at neuromuscular junctions, consistent with transport down motor axons and release at nerve terminals. At high resolution using immunoelectron microscopy, we detected ARIA immunoreactivity exclusively in the synaptic basal lamina in a pattern consistent with binding to synapse specific components on the presynaptic side of the basal lamina. These results support a role for ARIA as a trophic factor released by motor neuron terminals that may regulate the formation of mature neuromuscular synapses. PMID:7559763

1995-01-01

320

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

321

Vortex depinning in Josephson-junction arrays  

NASA Astrophysics Data System (ADS)

On the basis of a simple model we study the supercurrent-carrying capacity of a planar array of Josephson junctions. In particular we investigate the zero-temperature vortex-depinning current iBc, which is the largest supercurrent in an array containing one extra vortex on top of the ground-state vortex superlattice induced by an external magnetic field f. In the zero-field, f=0, case our results support the tilted-sinusoidal vortex-potential description of previous workers. However, in the fully frustrated, f=1/2 case, a more careful interpretation is required. We find that on the application of a transport current, the resulting vortex motion is not that of the extra vortex moving over a rigid field-induced vortex background. Rather, a vortex belonging to the checkerboard ground-state pattern first crosses over a junction into a neighboring ``empty'' plaquette. Then, the ``extra'' vortex moves to take its place. Our interpretation is based on a linear stability analysis, with the onset of vortex motion being associated with the vanishing of one eigenvalue of the stability matrix. Further applications of the method are suggested.

Dang, E. K. F.; Györffy, B. L.

1993-02-01

322

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

323

Spin Dependent Transport in Co Nano-Scale Tunnel Junctions  

E-print Network

to different orientation of the magnetization between the mag- netic electrodes (magnetoresistance) is given-resistors-in-series model. Single-, triple-, and five- junction arrays were fabricated and measured. In or- der to analyze not show any additional magnetoresistance over the two-junctions-in-series value at low voltage bias

Haviland, David

324

7. View eastsoutheast, junction of SR 141 and Rockland Road, ...  

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

7. View east-southeast, junction of SR 141 and Rockland Road, northern estate wall and tree lines left of center and western estate wall right of center - A. I. Du Pont Estate, Junction of State Route 141 & Rockland Road, Wilmington, New Castle County, DE

325

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

326

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

327

Methods for estimating junction temperature of AC LEDs  

Microsoft Academic Search

Light-emitting diodes operating on alternating current (AC) are gaining popularity in lighting applications. The junction temperature of an LED significantly influences performance. Although there are many proven methods for estimating the junction temperature of direct current (DC) LEDs, only a few methods have been proposed for AC LEDs. Two different methods were investigated and analyzed for their accuracy in estimating

Asiri Jayawardena; Yi-Wei Liu; Nadarajah Narendran

2011-01-01

328

Device properties of nanopore PN junction Si for photovoltaic application  

Microsoft Academic Search

Improvement of energy conversion efficiency of solar cells has led to innovative approaches, in particular the introduction of nanopillar photovoltaics [1]. Previous work on nanopillar Si photovoltaic has shown broadband reduction in optical reflection and enhancement of absorption [2]. Radial or axial PN junctions [3, 4] have been of high interest for improved photovoltaic devices. However, with the PN junction

Hyunjong Jin; Te Wei Chang; Logan Gang Liu

2011-01-01

329

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

330

Wideband frequency metrology using high temperature superconducting Josephson junctions  

Microsoft Academic Search

We have studied the responses of high temperature superconducting (HTS) Josephson junctions to monochromatic and polychromatic electromagnetic irradiations from 50 GHz to 4.25 THz. The highest operating frequency and the maximum value of normalized response are shown to be proportional to the ICRN product of the junction, where IC and RN are the critical current and normal resistance of the

Jian Chen; Yuhei Kurigata; Huabing Wang; Kensuke Nakajima; Tsutomu Yamashita; Peiheng Wu

2003-01-01

331

VORTEX PROPAGATION AND RADIATION EMISSION IN JOSEPHSON TUNNEL JUNCTIONS  

E-print Network

299 VORTEX PROPAGATION AND RADIATION EMISSION IN JOSEPHSON TUNNEL JUNCTIONS T. A. FULTON and L. N, JANVIER 1974, PAGE 1. Introduction. - The possible applications of microwave radiation from Josephson-field effects in tunnel junctions as they pertain to microwave emission. As is well-known, emission of radiation

Boyer, Edmond

332

Molecular Mechanism of Active Zone Organization at Vertebrate Neuromuscular Junctions  

PubMed Central

Organization of presynaptic active zones is essential for development, plasticity, and pathology of the nervous system. Recent studies indicate a trans-synaptic molecular mechanism that organizes the active zones by connecting the pre- and the postsynaptic specialization. The presynaptic component of this trans-synaptic mechanism is comprised of cytosolic active zone proteins bound to the cytosolic domains of voltage-dependent calcium channels (P/Q-, N-, and L-type) on the presynaptic membrane. The postsynaptic component of this mechanism is the synapse organizer (laminin ?2) that is expressed by the postsynaptic cell and accumulates specifically on top of the postsynaptic specialization. The pre- and the postsynaptic components interact directly between the extracellular domains of calcium channels and laminin ?2 to anchor the presynaptic protein complex in front of the postsynaptic specialization. Hence, the presynaptic calcium channel functions as a scaffolding protein for active zone organization and as an ion-conducting channel for synaptic transmission. In contrast to the requirement of calcium influx for synaptic transmission, the formation of the active zone does not require the calcium influx through the calcium channels. Importantly, the active zones of adult synapses are not stable structures and require maintenance for their integrity. Furthermore, aging or diseases of the central and peripheral nervous system impair the active zones. This review will focus on the molecular mechanisms that organize the presynaptic active zones and summarize recent findings at the neuromuscular junctions and other synapses. PMID:22135013

Nishimune, Hiroshi

2013-01-01

333

Investigation of redox processes at semiconductor electrode liquid junctions  

SciTech Connect

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

Koval, C.A.

1990-08-01

334

Multiterminal Nanowire Junctions of Silicon: A Theoretical Prediction of Atomic Structure and Electronic Properties  

NASA Astrophysics Data System (ADS)

Using empirical scheme, atomic structure of a new exotic class of silicon nanoclusters was elaborated upon the central icosahedral core (Si-IC) and pentagonal petals (Si-PP) growing from Si-IC vertexes. It was shown that Si-IC/Si-PP interface formation is energetically preferable. Some experimental observations of silicon nanostructures can be explained by presence of the proposed objects. The Extended Huckel Theory electronic structure calculations demonstrate an ability of the proposed objects to act as nanoscale tunnel junctions.

Avramov, Pavel V.; Chernozatonskii, Leonid A.; Sorokin, Pavel B.; Gordon, Mark S.

2007-07-01

335

Functional xylem anatomy in root-shoot junctions of six cereal species.  

PubMed

In cereals, the formation of safety zones in the root-shoot junction could protect the vessels of roots from embolism originating in the shoot. The root-shoot junction was examined both anatomically, with a light microscope, and experimentally, using a pressurized-air method, in the base of seminal and adventitious roots of maize (Zea mays L. cv. Seneca 60-II), a corngrass mutation of maize (Cg mutant), sorghum (Sorghum bicolor L. cv. Ho-Pak), winter oats (Avena sativa L. cv. Ogle), spring wheat (Triticum aestivum L. cv. Glenlea), winter wheat (T. aestivum cv. Monopol), winter barley (Hordeum vulgare L. cv. Wysor), spring rye (Secale cereale L. cv. JO-02 Finland), and winter rye (S. cereale cv. Musketeer). Two types of hydraulic architecture were found in the cereal roots: (i) a very safe root vessel system, as in winter rye, in which the vessels of the roots are separated from those of the shoots by tracheids, versus (ii) a completely unsafe system, as in corngrass, where the vessels in the root are continuous with the vessels in the shoot. The xylem anatomy of the seminal roots is generally correlated with the species-specific overall root morphology. Rye, wheat and barley, which develop four to six seminal roots, show a high degree of vascular segmentation resulting in, the formation of safe root vessels; maize, sorghum and oats, which typically develop a primary seminal root, contain unsafe vessels that are continuous through the mesocotyl and through the first node. In adventitious roots, vascular segmentation is not related to overall root morphology. Differences in the proportion of safe adventitious roots in which all the vessels end in the root-shoot junction range from 9 to 98% in the cereals studied. In the unsafe roots of these cereals, the number of vessels per root that are continuous through the junction range from 1 to 14. As significant differences in vascular segmentation of the root-shoot junction occur not only between species, but also between cultivars, we suggest that selection based on the occurrence of safety zones might be used in breeding programs designed to improve adaptation of cereals to drought and cold temperatures. PMID:24193938

Aloni, R; Griffith, M

1991-04-01

336

Quasi-optical Josephson-junction oscillator arrays  

NASA Technical Reports Server (NTRS)

Josephson junctions are natural voltage-controlled oscillators capable of generating submillimeter-wavelength radiation, but a single junction usually can produce only 100 nW of power and often has a broad spectral linewidth. The authors are investigating 2D quasi-optical power combining arrays of 103 and 104 NbN/MgO/NbN and Nb/Al-AlO(x)/Nb junctions to overcome these limitations. The junctions are dc-biased in parallel and are distributed along interdigitated lines. The arrays couple to a resonant mode of a Fabry-Perot cavity to achieve mutual phase-locking. The array configuration has a relatively low impedance, which should allow the capacitance of the junctions to be tuned out at the oscillation frequency.

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

1993-01-01

337

The role of titanium in electromigrated tunnel junctions  

NASA Astrophysics Data System (ADS)

A standard route for fabrication of nanoscopic tunnel junctions is via electromigration of lithographically prepared gold nanowires. In the lithography process, a thin adhesion layer, typically titanium, is used to promote the adhesion of the gold nanowires to the substrate. Here, we demonstrate that such an adhesion layer plays a vital role in the electrical transport behavior of electromigrated tunnel junctions. We show that junctions fabricated from gold deposited on top of a titanium adhesion layer are electrically stable at ambient conditions, in contrast to gold junctions without a titanium adhesion layer. We furthermore find that electromigrated junctions fabricated from pure titanium are electrically exceptionally stable. Based on our transport data, we provide evidence that the barrier in gold-on-titanium tunnel devices is formed by the native oxide of titanium.

Frimmer, Martin; Puebla-Hellmann, Gabriel; Wallraff, Andreas; Novotny, Lukas

2014-12-01

338

Role of magnetic anisotropy in spin-filter junctions  

NASA Astrophysics Data System (ADS)

We have fabricated oxide-based spin-filter junctions in which we demonstrate that magnetic anisotropy can be used to tune the transport behavior of spin-filter junctions. We have demonstrated spin-filtering behavior in La0.7Sr0.3MnO3/CoCr2O4/Fe3O4 and La0.7Sr0.3MnO3/MnCr2O4/Fe3O4 junctions where the interface anisotropy plays a significant role in determining transport behavior. Detailed studies of chemical and magnetic structure at the interfaces indicate that abrupt changes in magnetic anisotropy across the nonisostructural interface is the cause of the significant suppression of junction magnetoresistance in junctions with MnCr2O4 barrier layers.

Chopdekar, R. V.; Nelson-Cheeseman, B. B.; Liberati, M.; Arenholz, E.; Suzuki, Y.

2011-06-01

339

Emission of microwave photon pairs by a tunnel junction.  

PubMed

We report the observation of photon pairs in the photoassisted shot noise of a tunnel junction in the quantum regime at very high frequency and very low temperature. We have measured the fluctuations of the noise power generated by the junction at two different frequencies, f(1) = 4.4 and f(2) = 7.2 GHz, while driving the junction with a microwave excitation of frequency f(0) = f(1) + f(2). We observe clear correlations between the fluctuations of the two noise powers even when the mean photon number per measurement is much smaller than one. This is strong evidence for photons being emitted in pairs. We also demonstrate that the electromagnetic field generated by the junction exhibits two-mode amplitude squeezing, a proof of its nonclassicality. The data agree very well with predictions based on the fourth cumulant of the current fluctuations generated by the junction. PMID:25105619

Forgues, Jean-Charles; Lupien, Christian; Reulet, Bertrand

2014-07-25

340

Many faces of drebrin: from building dendritic spines and stabilizing gap junctions to shaping neurite-like cell processes  

Microsoft Academic Search

In this review we consider the multiple functions of developmentally regulated brain protein (drebrin), an actin-binding protein,\\u000a in the formation of cellular polarity in different cell types. Drebrin has a well-established role in the morphogenesis, patterning\\u000a and maintenance of dendritic spines in neurons. We have recently shown that drebrin also stabilizes Connexin-43 containing\\u000a gap junctions at the plasma membrane. The

Irina Majoul; Tomoaki Shirao; Yuko Sekino; Rainer Duden

2007-01-01

341

Scattering form factors for self-assembled network junctions  

NASA Astrophysics Data System (ADS)

The equilibrium microstructures in microemulsions and other self-assembled systems show complex, connected shapes such as symmetric bicontinuous spongelike structures and asymmetric bicontinuous networks formed by cylinders interconnected at junctions. In microemulsions, these cylinder network microstructures may mediate the structural transition from a spherical or globular phase to the bicontinuous microstructure. To understand the structural and statistical properties of such cylinder network microstructures as measured by scattering experiments, models are needed to extract the real-space structure from the scattering data. In this paper, we calculate the scattering functions appropriate for cylinder network microstructures. We focus on such networks that contain a high density of network junctions that connect the cylindrical elements. In this limit, the network microstructure can be regarded as an assembly of randomly oriented, closed packed network junctions (i.e., the cylinder scattering contributions are neglected). Accordingly, the scattering spectrum of the network microstructure can be calculated as the product of the junction number density, the junction form factor, which describes the scattering from the surface of a single junction, and a structure factor, which describes the local correlations of different junctions due to junction interactions (including their excluded volume). This approach is applied to analyze the scattering data from a bicontinuous microemulsion with equal volumes of water and oil. In a second approach, we included the cylinder scattering contribution in the junction form factor by calculating the scattering intensity of Y junctions to which three rods with spherical cross section are attached. The respective theoretical predictions are compared with results of neutron scattering measurements on a water-in-oil microemulsion with a connected microstructure.

Foster, T.; Safran, S. A.; Sottmann, T.; Strey, R.

2007-11-01

342

The bacteroides NBU1 integrase performs a homology-independent strand exchange to form a holliday junction intermediate.  

PubMed

The Bacteroides mobilizable transposon NBU1 uses an integrase (IntN1) that is a tyrosine recombinase for its integration and excision from the host chromosome. Previously we showed that IntN1 makes 7-bp staggered cuts within the NBU1 att sites, and certain mismatches within the crossover region of the attN1 site (G(-2)C attN1) or the chromosomal target site (C(-3)G attBT1-1) enhanced the in vivo integration efficiency. Here we describe an in vitro integration system for NBU1. We used nicked substrates and a Holliday junction trapping peptide to show that NBU1 integration proceeds via formation of a Holliday junction intermediate that is formed by exchange of bottom strands. Some mismatches next to the first strand exchange site (in reactions with C(-3)G attBT1-1 or G(-2)C attN1 with their wild-type partner site) not only allowed formation of the Holliday junction intermediate but also increased the rate of recombinant formation. The second strand exchange appears to be homology-dependent. IntN1 is the only tyrosine recombinase known to catalyze a reaction that is more efficient in the presence of mismatches and where the first strand exchange is homology-independent. The possible mechanisms by which the mismatches stimulate recombination are discussed. PMID:17766246

Rajeev, Lara; Segall, Anca; Gardner, Jeffrey

2007-10-26

343

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

344

Regional differences in cell shape and gap junction expression in rat Achilles tendon: relation to fibrocartilage differentiation  

PubMed Central

Tendon cells have complex shapes, with many cell processes and an intimate association with collagen fibre bundles in their extracellular matrix. Where cells and their processes contact one another, they form gap junctions. In the present study, we have examined the distribution of gap junction components in phenotypically different regions of rat Achilles tendon. This tendon contains a prominent enthesial fibrocartilage at its calcaneal attachment and a sesamoid fibrocartilage where it is pressed against the calcaneus just proximal to the attachment. Studies using DiI staining demonstrated typical stellate cell shape in transverse sections of pure tendon, with cells withdrawing their cell processes and rounding up in the fibrocartilaginous zones. Coincident with change in shape, cells stopped expressing the gap junction proteins connexins 32 and 43, with connexin 43 disappearing earlier in the transition than connexin 32. Thus, there are major differences in the ability of cells to communicate with one another in the phenotypically distinct regions of tendon. Individual fibrocartilage cells must sense alterations in the extracellular matrix by cell/matrix interactions, but can only coordinate their behaviour via indirect cytokine and growth factor signalling. The tendon cells have additional possibilities — in addition to the above, they have the potential to communicate direct cytoplasmic signals via gap junctions. The formation of fibrocartilage in tendons occurs because of the presence of compressive as well as tensile forces. It may be that different systems are used to sense and respond to such forces in fibrous and cartilaginous tissues. PMID:9827637

RALPHS, J. R.; BENJAMIN, M.; WAGGETT, A. D.; RUSSELL, D. C.; MESSNER, K.; GAO, J.

1998-01-01

345

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

346

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

347

Guiding chemical pulses through geometry: Y junctions.  

PubMed

We study computationally and experimentally the propagation of chemical pulses in complex geometries. The reaction of interest, CO oxidation, takes place on single crystal Pt(110) surfaces that are microlithographically patterned; they are also addressable through a focused laser beam, manipulated through galvanometer mirrors, capable of locally altering the crystal temperature and thus affecting pulse propagation. We focus on sudden changes in the domain shape (corners in a Y-junction geometry) that can affect the pulse dynamics; we also show how brief, localized temperature perturbations can be used to control reactive pulse propagation. The computational results are corroborated through experimental studies in which the pulses are visualized using reflection anisotropy microscopy. PMID:16605643

Qiao, L; Kevrekidis, I G; Punckt, C; Rotermund, H H

2006-03-01

348

Ferromagnetism inside of magnetic tunneling junctions  

NASA Astrophysics Data System (ADS)

Over this past summer I performed research with different annealing temperatures cooling rates for Magnetic Tunneling Junctions (MTJ's). The MTJ's were composed of a 3nm FeCoB ferromagnet, a 1.6 nm MgO tunneling barrier, and a 3nm FeCoB ferromagnet pinned by a 15nm IrMn anti-ferromagnet. This speech also includes a review of concepts that include; coercivity (of the free and fixed layer), Tunneling Magneto resistance (TMR), exchange bias, and a basic concept of the parallel/anti-parallel configuration of the sample and how this affects resistance. This particular study was on two things; *How the maximum thermal annealing temperature affects TMR. *How holding the maximum thermal annealing temperature constant and varying the cooling rates (.2 c/sec, 2 c/sec, 137 c/sec) affects the coercivity of the free layer and the exchange bias.

Mesa, Glennie

2010-10-01

349

TEM characterization of a magnetic tunnel junction  

NASA Astrophysics Data System (ADS)

TEM characterization of a CoFeB/MgO/CoFeB magnetic tunnel junction (MTJ) has been performed. A TEM cross section was prepared using focused ion beam (FIB) milling techniques. However, the high energy Ga+ beam causes sample damage and induces the redeposition of the sputtered materials on the section surface. Complementary investigation of the crystal structure of the active trilayer in the MTJ was performed by depositing films directly onto a TEM holey carbon film. The TEM imaging, selected area electron diffraction (SAED) and energy dispersive X-ray (EDX) analysis were employed to study the nanostructure. The MgO layer is found to be incompletely crystalline with randomly oriented MgO crystallites. The CoFeB layer is amorphous and is homogenously deposited.

Harnchana, V.; Brown, A. P.; Brydson, R. M.; Harrington, J. P.; Hindmarch, A. T.; Marrows, C. H.; Hickey, B. J.

2008-08-01

350

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

351

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

352

Metallic conductance in single-molecule junctions  

NASA Astrophysics Data System (ADS)

Through break junction techniques it has become possible to attach metallic wires to individual molecules. The actual presence of the molecule, its identity, and the numbers of molecules involved in the transport in many cases need to be deduced from measurements of current and voltage only. In parallel, several implementations of non-equilibrium Greens function approaches in combination with density functional theory have been developed in order to compute the properties of molecular junctions. For a sensitive test of the computational models there is a need for more detailed experimental observations on well-characterized model systems. In our experiments we focus on such model systems. They are simple, small molecules which have the advantage that they are relatively easy to handle in computations and they allow for more precise experimental tests at low temperatures. The molecules we have studied include H2, H2O, CO, CO2, C6H6 (benzene), and C60 contacted between Pt leads. The molecular levels hybridize strongly with the Pt metal giving rise to a high conductance. The presence of the molecules can be confirmed by the detection of vibration modes. These modes are visible in the differential conductance, dI/dV, as a function of voltage bias as fine steps at the energies eV=?n corresponding to those of the vibration modes. Further test involve isotope-substituted molecules and stretching of the molecular bridge in order to detect shifts in the energy of the modes. The conductance of a single-molecule bridge cannot be uniquely distinguished from bridges due to several parallel channels. However, by measuring shot noise, i.e. the intrinsic noise in the electron current, it is possible to show that the current is carried by a single molecule. For other molecules the measurement gives evidence that the molecule provides two, or sometimes more channels for conductance. The results are compared with state of the art non-equilibrium DFT calculations.

van Ruitenbeek, Jan

2010-03-01

353

Epithelial junctions and Rho family GTPases: the zonular signalosome.  

PubMed

The establishment and maintenance of epithelial cell-cell junctions is crucially important to regulate adhesion, apico-basal polarity and motility of epithelial cells, and ultimately controls the architecture and physiology of epithelial organs. Junctions are supported, shaped and regulated by cytoskeletal filaments, whose dynamic organization and contractility are finely tuned by GTPases of the Rho family, primarily RhoA, Rac1 and Cdc42. Recent research has identified new molecular mechanisms underlying the cross-talk between these GTPases and epithelial junctions. Here we briefly summarize the current knowledge about the organization, molecular evolution and cytoskeletal anchoring of cell-cell junctions, and we comment on the most recent advances in the characterization of the interactions between Rho GTPases and junctional proteins, and their consequences with regards to junction assembly and regulation of cell behavior in vertebrate model systems. The concept of "zonular signalosome" is proposed, which highlights the close functional relationship between proteins of zonular junctions (zonulae occludentes and adhaerentes) and the control of cytoskeletal organization and signaling through Rho GTPases, transcription factors, and their effectors. PMID:25483301

Citi, Sandra; Guerrera, Diego; Spadaro, Domenica; Shah, Jimit

2014-10-01

354

Mechanical deformations of boron nitride nanotubes in crossed junctions  

SciTech Connect

We present a study of the mechanical deformations of boron nitride nanotubes (BNNTs) in crossed junctions. The structure and deformation of the crossed tubes in the junction are characterized by using atomic force microscopy. Our results show that the total tube heights are reduced by 20%–33% at the crossed junctions formed by double-walled BNNTs with outer diameters in the range of 2.21–4.67?nm. The measured tube height reduction is found to be in a nearly linear relationship with the summation of the outer diameters of the two tubes forming the junction. The contact force between the two tubes in the junction is estimated based on contact mechanics theories and found to be within the range of 4.2–7.6 nN. The Young's modulus of BNNTs and their binding strengths with the substrate are quantified, based on the deformation profile of the upper tube in the junction, and are found to be 1.07?±?0.11 TPa and 0.18–0.29 nJ/m, respectively. Finally, we perform finite element simulations on the mechanical deformations of the crossed BNNT junctions. The numerical simulation results are consistent with both the experimental measurements and the analytical analysis. The results reported in this paper contribute to a better understanding of the structural and mechanical properties of BNNTs and to the pursuit of their applications.

Zhao, Yadong; Chen, Xiaoming; Ke, Changhong, E-mail: cke@binghamton.edu [Department of Mechanical Engineering, State University of New York at Binghamton, Binghamton, New York 13902 (United States); Park, Cheol [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Fay, Catharine C. [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Stupkiewicz, Stanislaw [Institute of Fundamental Technological Research, Warsaw (Poland)

2014-04-28

355

A histone octamer blocks branch migration of a Holliday junction.  

PubMed Central

The Holliday junction is a key intermediate in genetic recombination. Here, we examine the effect of a nucleosome core on movement of the Holliday junction in vitro by spontaneous branch migration. Histone octamers consisting of H2A, H2B, H3, and H4 are reconstituted onto DNA duplexes containing an artificial nucleosome-positioning sequence consisting of a tandem array of an alternating AT-GC sequence motif. Characterization of the reconstituted branch migration substrates by micrococcal nuclease mapping and exonuclease III and hydroxyl radical footprinting reveal that 70% of the reconstituted octamers are positioned near the center of the substrate and the remaining 30% are located at the distal end, although in both cases some translational degeneracy is observed. Branch migration assays with the octamer-containing substrates reveal that the Holliday junction cannot migrate spontaneously through DNA organized into a nucleosomal core unless DNA-histone interactions are completely disrupted. Similar results are obtained with branch migration substrates containing an octamer positioned on a naturally occurring sequence derived from the yeast GLN3 locus. Digestion of Holliday junctions with T7 endonuclease I establishes that the junction is not trapped by the octamer but can branch migrate in regions free of histone octamers. Our findings suggest that migration of Holliday junctions during recombination and the recombinational repair of DNA damage requires proteins not only to accelerate the intrinsic rate of branch migration but also to facilitate the passage of the Holliday junction through a nucleosome. PMID:9372946

Grigoriev, M; Hsieh, P

1997-01-01

356

Pallidal gap junctions-triggers of synchrony in Parkinson's disease?  

PubMed Central

Although increased synchrony of the neural activity in the basal ganglia may underlie the motor deficiencies exhibited in Parkinson's disease (PD), how this synchrony arises, propagates through the basal ganglia, and changes under dopamine replacement remains unknown. Gap junctions could play a major role in modifying this synchrony, because they show functional plasticity under the influence of dopamine and after neural injury. In this study, confocal imaging was used to detect connexin-36, the major neural gap junction protein, in postmortem tissues of PD patients and control subjects in the putamen, subthalamic nucleus (STN), and external and internal globus pallidus (GPe and GPi, respectively). Moreover, we quantified how gap junctions affect synchrony in an existing computational model of the basal ganglia. We detected connexin-36 in the human putamen, GPe, and GPi, but not in the STN. Furthermore, we found that the number of connexin-36 spots in PD tissues increased by 50% in the putamen, 43% in the GPe, and 109% in the GPi compared with controls. In the computational model, gap junctions in the GPe and GPi strongly influenced synchrony. The basal ganglia became especially susceptible to synchronize with input from the cortex when gap junctions were numerous and high in conductance. In conclusion, connexin-36 expression in the human GPe and GPi suggests that gap junctional coupling exists within these nuclei. In PD, neural injury and dopamine depletion could increase this coupling. Therefore, we propose that gap junctions act as a powerful modulator of synchrony in the basal ganglia. PMID:25124148

Schwab, Bettina C; Heida, Tjitske; Zhao, Yan; van Gils, Stephan A; van Wezel, Richard J A

2014-01-01

357

The k-junction motif in RNA structure  

PubMed Central

The k-junction is a structural motif in RNA comprising a three-way helical junction based upon kink turn (k-turn) architecture. A computer program written to examine relative helical orientation identified the three-way junction of the Arabidopsis TPP riboswitch as an elaborated k-turn. The Escherichia coli TPP riboswitch contains a related k-junction, and analysis of >11 000 sequences shows that the structure is common to these riboswitches. The k-junction exhibits all the key features of an N1-class k-turn, including the standard cross-strand hydrogen bonds. The third helix of the junction is coaxially aligned with the C (canonical) helix, while the k-turn loop forms the turn into the NC (non-canonical) helix. Analysis of ligand binding by ITC and global folding by gel electrophoresis demonstrates the importance of the k-turn nucleotides. Clearly the basic elements of k-turn structure are structurally well suited to generate a three-way helical junction, retaining all the key features and interactions of the k-turn. PMID:24531930

Wang, Jia; Daldrop, Peter; Huang, Lin; Lilley, David M. J.

2014-01-01

358

Study on electrical properties of metal/GaSb junctions using metal-GaSb alloys  

NASA Astrophysics Data System (ADS)

We study the metal-GaSb alloy formation, the structural properties and the electrical characteristics of the metal-alloy/GaSb diodes by employing metal materials such as Ni, Pd, Co, Ti, Al, and Ta, in order to clarify metals suitable for GaSb p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) as metal-GaSb alloy source/drain (S/D). It is found that Ni, Pd, Co, and Ti can form alloy with GaSb by rapid thermal annealing at 250, 250, 350, and 450 °C, respectively. The Ni-GaSb and Pd-GaSb alloy formation temperature of 250 °C is lower than the conventional dopant activation annealing for ion implantation, which enable us to lower the process temperature. The alloy layers show lower sheet resistance (RSheet) than that of p+-GaSb layer formed by ion implantation and activation annealing. We also study the electrical characteristics of the metal-alloy/GaSb junctions. The alloy/n-GaSb contact has large Schottky barrier height (?B) for electrons, ˜0.6 eV, and low ?B for holes, ˜0.2 eV, which enable us to realize high on/off ratio in pMOSFETs. We have found that the Ni-GaSb/GaSb Schottky junction shows the best electrical characteristics with ideal factor (n) of 1.1 and on-current/off-current ratio (Ion/Ioff) of ˜104 among the metal-GaSb alloy/GaSb junctions evaluated in the present study. These electrical properties are also superior to those of a p+-n diode fabricated by Be ion implantation with activation annealing at 350 °C. As a result, the Ni-GaSb alloy can be regarded as one of the best materials to realize metal S/D in GaSb pMOSFETs.

Nishi, Koichi; Yokoyama, Masafumi; Kim, Sanghyeon; Yokoyama, Haruki; Takenaka, Mitsuru; Takagi, Shinichi

2014-01-01

359

Ultrastructural analysis of chemical synapses and gap junctions between Drosophila brain neurons in culture.  

PubMed

Dissociated cultures from many species have been important tools for exploring factors that regulate structure and function of central neuronal synapses. We have previously shown that cells harvested from brains of late stage Drosophila pupae can regenerate their processes in vitro. Electrophysiological recordings demonstrate the formation of functional synaptic connections as early as 3 days in vitro (DIV), but no information about synapse structure is available. Here, we report that antibodies against pre-synaptic proteins Synapsin and Bruchpilot result in punctate staining of regenerating neurites. Puncta density increases as neuritic plexuses develop over the first 4 DIV. Electron microscopy reveals that closely apposed neurites can form chemical synapses with both pre- and postsynaptic specializations characteristic of many inter-neuronal synapses in the adult brain. Chemical synapses in culture are restricted to neuritic processes and some neurite pairs form reciprocal synapses. GABAergic synapses have a significantly higher percentage of clear core versus granular vesicles than non-GABA synapses. Gap junction profiles, some adjacent to chemical synapses, suggest that neurons in culture can form purely electrical as well as mixed synapses, as they do in the brain. However, unlike adult brain, gap junctions in culture form between neuronal somata as well as neurites, suggesting soma ensheathing glia, largely absent in culture, regulate gap junction location in vivo. Thus pupal brain cultures, which support formation of interneuronal synapses with structural features similar to synapses in adult brain, are a useful model system for identifying intrinsic and extrinsic regulators of central synapse structure as well as function. PMID:18044733

Oh, Hyun-Woo; Campusano, Jorge M; Hilgenberg, Lutz G W; Sun, Xicui; Smith, Martin A; O'Dowd, Diane K

2008-02-15

360

Supraspinatus rupture at the musculotendinous junction in a young woman.  

PubMed

The vast majority of rotator cuff tears occur within the tendon or as an avulsion from the greater tuberosity. Supraspinatus injury at the musculotendinous junction is a very uncommon event. We describe a case of supraspinatus rupture at the musculotendinous junction, with successful conservative treatment. It occurred in a 23-year-old woman, the youngest patient with this uncommon type of injury. To our knowledge, this is the first case of rupture of the supraspinatus muscle at the musculotendinous junction in a young woman and the second in a woman. PMID:24292386

Benazzo, Francesco; Marullo, Matteo; Pietrobono, Luigi

2014-09-01

361

The radio-frequency impedance of individual intrinsic Josephson junctions  

SciTech Connect

We have measured the response of an array of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} intrinsic Josephson junctions to irradiation at 3 GHz. By measuring the dependence of the switching current upon the radio-frequency current for five of the junctions in the array we show quantitatively that the junctions have identical impedances at 3 GHz, this impedance being given by the inverse of the slope of the current-voltage characteristics.

Leiner, Johannes; Saleem, Sajid; Fenton, J. C.; Warburton, P. A. [London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Yamamoto, Takashi; Kadowaki, Kazuo [Institute of Materials Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

2009-12-21

362

Josephson junctions with tunable current-phase relation  

NASA Astrophysics Data System (ADS)

We consider 0-? Josephson junctions consisting of 0 and ? regions of lengths L0 and L? with critical current densities jc 0 and jc ?, respectively. The dependence of the Josephson current on the phase-shift averaged along the junction is derived. We show that these systems exhibit the main features of ? Josephson junctions—the ground state is doubly degenerate and the current-phase relation can be tuned in situ by applying magnetic field. In the limit of short and long 0 and ? regions, the current phase relation is derived analytically. In the case of intermediate lengths of 0 and ? regions, the current-phase relation is calculated numerically.

Lipman, A.; Mints, R. G.; Kleiner, R.; Koelle, D.; Goldobin, E.

2014-11-01

363

Effect of current injection into thin-film Josephson junctions  

NASA Astrophysics Data System (ADS)

New thin-film Josephson junctions have recently been tested in which the current injected into one of the junction banks governs Josephson phenomena. One thus can continuously manage the phase distribution at the junction by changing the injected current. A method of calculating the distribution of injected currents is proposed for a half-infinite thin-film strip with source-sink points at arbitrary positions at the film edges. The strip width W is assumed small relative to ? =2 ?2/d ;? is the bulk London penetration depth of the film material and d is the film thickness.

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

2014-11-01

364

Statistical mechanics of strings with Y-junctions  

SciTech Connect

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

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

2008-07-15

365

Gap junction modulation and its implications for heart function  

PubMed Central

Gap junction communication (GJC) mediated by connexins is critical for heart function. To gain insight into the causal relationship of molecular mechanisms of disease pathology, it is important to understand which mechanisms contribute to impairment of gap junctional communication. Here, we present an update on the known modulators of connexins, including various interaction partners, kinases, and signaling cascades. This gap junction network (GJN) can serve as a blueprint for data mining approaches exploring the growing number of publicly available data sets from experimental and clinical studies. PMID:24578694

Kurtenbach, Stefan; Kurtenbach, Sarah; Zoidl, Georg

2014-01-01

366

Magnetoresistive junctions based on epitaxial graphene and hexagonal boron nitride  

NASA Astrophysics Data System (ADS)

We propose monolayer epitaxial graphene and hexagonal boron nitride (h-BN) as ultimate thickness covalent spacers for magnetoresistive junctions. Using a first-principles approach, we investigate the structural, magnetic, and spin transport properties of such junctions based on structurally well-defined interfaces with (111) fcc or (0001) hcp ferromagnetic transition metals. We find low resistance area products, strong exchange couplings across the interface, and magnetoresistance ratios exceeding 100% for certain chemical compositions. These properties can be fine tuned, making the proposed junctions attractive for nanoscale spintronics applications.

Yazyev, Oleg V.; Pasquarello, Alfredo

2009-07-01

367

Statistical mechanics of strings with Y-junctions  

E-print Network

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

R. J. Rivers; D. A. Steer

2008-03-27

368

Junction Temperature Measurement of IGBTs Using Short Circuit Current  

SciTech Connect

In this paper, a method is proposed to measure the junction temperatures of IGBT discrete devices and modules using short circuit current. Experimental results show that the short circuit current has good sensitivity, linearity and selectivity, which is suitable to be used as temperature sensitive electrical parameters (TSEP). Test circuit and hardware design are proposed for junction temperature measurement in single phase and three phase convertes. By connecting a temperature measurement unit to the converter and giving a short circuit pulse, the IGBT junction temperature can be measured.

Wang, Fei [ORNL; Xu, Zhuxian [ORNL; Ning, Puqi [ORNL

2012-01-01

369

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

Microsoft Academic Search

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

Richard R. Shivers

1977-01-01

370

Co{sub 2}MnSi Heusler alloy as magnetic electrodes in magnetic tunnel junctions  

SciTech Connect

As a consequence of the growing theoretical predictions of 100% spin-polarized half- and full-Heusler compounds over the past six years, Heusler alloys are among the most promising materials class for future magnetoelectronic and spintronic applications. We have integrated Co{sub 2}MnSi, as a representative of the full-Heusler compound family, as one magnetic electrode into magnetic tunnel junctions. The preparation strategy has been chosen so as to sputter Co{sub 2}MnSi at room temperature onto a V-buffer layer, which assists in (110) texture formation, and to deposit the Al-barrier layer directly thereafter. After plasma oxidizing the Al-barrier layer, subsequent annealing leads (1) to the texture formation and (2) to the appropriate atomic ordering within the Co{sub 2}MnSi, and (3) homogenizes the AlO{sub x} barrier. It is shown that the magnetic switching of the ferromagnetic electrodes is well controlled from room temperature down to 10 K. The resulting tunnel magnetoresistance-effect amplitude of the Co{sub 2}MnSi containing magnetic tunnel junctions has been determined as a function of temperature and the spin polarization of the Co{sub 2}MnSi Heusler compound has been estimated to be 61% at 10 K. Thus, the spin polarization of the Co{sub 2}MnSi layer at 10K exceeds that of conventional transition metals.

Kaemmerer, S.; Thomas, A.; Huetten, A.; Reiss, G. [Department of Physics, University of Bielefeld, D-33615 Bielefeld (Germany)

2004-07-05

371

Simultaneous Determination of Conductance and Thermopower of Single Molecule Junctions  

E-print Network

molecular orbital (LUMO), respectively. We find that the Seebeck coefficient is negative for pyridine the accessible temperature gradients (Seebeck coefficient on temperature. From histograms of thousands of junctions, we use the most probable Seebeck

Venkataraman, Latha

372

Quantum fluctuations and quantum dynamics of small Josephson junctions  

NASA Astrophysics Data System (ADS)

The quantum properties of small Josephson junctions with both linear Ohmic and quasiparticle (“cosine”) dissipation are investigated by means of a real-time path-integral technique. Quantum diffusion of the quasicharge and quantum corrections to the classical conductivity are analyzed. The current-voltage characteristics and the effect of voltage steps are studied. It is shown that coherent voltage oscillations may exist not only for small, but also for large values of the junction tunneling conductivity. For not very small values of the quasiparticle conductivity of the junction the frequency of these oscillations is twice the Bloch oscillation frequency. The quantum dynamics of the phase difference across the junction is studied for a wide region of parameters. It is shown that linear and “cosine” dissipation mechanisms cause the presence of two dissipative phase transitions, which are qualitatively different from each other in many aspects.

Panyukov, S. V.; Zaikin, A. D.

1988-10-01

373

Quantum dynamics of ultrasmall tunnel junctions: Real-time analysis  

NASA Astrophysics Data System (ADS)

We present a real-time path-integral analysis of the quantum dynamics of an ultrasmall tunnel junction interacting with an arbitrary external impedance. For a normal junction, we derive a quasiclassical Langevin equation for the phase variable and calculate the I-V curve beyond perturbation theory for the junction conductance. In the superconducting case, we develop a nonperturbative calculation of the time-dependent expectation value of the voltage operator and voltage-voltage correlation functions. Provided that dissipation is small enough, both of these quantities show damped oscillations and a power-law decay in the low-temperature limit. We also analyze the effect of resonant voltage steps on the I-V curve of an ac-driven tunnel junction and evaluate the linewidth of Bloch oscillations in the quantum limit.

Golubev, D. S.; Zaikin, A. D.

1992-11-01

374

View southwest; detail view of junction between northerly canopy and ...  

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

View southwest; detail view of junction between northerly canopy and station - New Canaan Railroad Station, Approximately 200 feet southwest of intersection of Park & Elm Streets & approximately 150 feet north of Pine Street, New Canaan, Fairfield County, CT

375

8. VIEW SOUTHWEST, DETAIL OF JUNCTION OF EAST AND NORTH ...  

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

8. VIEW SOUTHWEST, DETAIL OF JUNCTION OF EAST AND NORTH ELEVATIONS AT PORCH ROOF LEVEL SHOWING GLAZED HEADERS AND BELT COURSE - David Sterrett House, State Game Lands Plot No. 169 (Upper Mifflin Township), Newville, Cumberland County, PA

376

B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore ...  

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

B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.85. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

377

Union Junction Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, ...  

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

Union Junction Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.49. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

378

Gap junctions: multifaceted regulators of embryonic cortical development  

PubMed Central

The morphological development of the cerebral cortex from a primitive neuroep ithelium into a complex laminar structure underlying higher cognition must rely on a network of intercellular signaling. Gap junctions are widely expressed during embryonic development and provide a means of cell-cell contact and communication. We review the roles of gap junctions in regulating the proliferation of neural progenitors as well as the migration and differentiation of young neurons in the embryonic cerebral cortex. There is substantial evidence that although gap junctions act in the classical manner coupling neural progenitors, they also act as hemichannels mediating the spread of calcium waves across progenitor cell populations and as adhesive molecules aiding neuronal migration. Gap junctions are thus emerging as multifaceted regulators of cortical development playing diverse roles in intercellular communication. PMID:18403031

2008-01-01

379

Manipulating Josephson junctions in thin-films by nearby vortices  

NASA Astrophysics Data System (ADS)

It is shown that a vortex trapped in one of the banks of a planar edge-type Josephson junction in a narrow thin-film superconducting strip can change drastically the dependence of the junction critical current on the applied field, Ic(H). When the vortex is placed at certain discrete positions in the strip middle, the pattern Ic(H) has zero at H=0 instead of the traditional maximum of ‘0-type’ junctions. The number of these positions is equal to the number of vortices trapped at the same location. When the junction-vortex separation exceeds ?W, the strip width, Ic(H) is no longer sensitive to the vortex presence. The same is true for any separation if the vortex approaches the strip edges.

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

2014-07-01

380

Single-charge detection by an atomic precision tunnel junction  

SciTech Connect

We demonstrate sensitive detection of single charges using a planar tunnel junction 8.5?nm wide and 17.2?nm long defined by an atomically precise phosphorus doping profile in silicon. The conductance of the junction responds to a nearby gate potential and also to changes in the charge state of a quantum dot patterned 52?nm away. The response of this detector is monotonic across the entire working voltage range of the device, which will make it particularly useful for studying systems of multiple quantum dots. The charge sensitivity is maximized when the junction is most conductive, suggesting that more sensitive detection can be achieved by shortening the length of the junction to increase its conductance.

House, M. G., E-mail: matthew.house@unsw.edu.au; Peretz, E.; Keizer, J. G.; Hile, S. J.; Simmons, M. Y., E-mail: michelle.simmons@unsw.edu.au [Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney, NSW 2052 (Australia)

2014-03-17

381

PAINT SHOP, DETAIL OF FABRICATED COLUMN AT JUNCTION OF WEST ...  

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

PAINT SHOP, DETAIL OF FABRICATED COLUMN AT JUNCTION OF WEST BAY (ORIGINAL) AND CENTER BAYS (SECOND ADDITION), LOOKING NORTHEAST. - Southern Pacific, Sacramento Shops, Paint Shop, 111 I Street, Sacramento, Sacramento County, CA

382

Epithelial cell polarity and cell junctions in drosophila  

E-print Network

The polarized architecture of epithelial cells and tissues is a fundamental determinant of animal anatomy and physiology. Recent progress made in the genetic and molecular analysis of epithelial polarity and cellular junctions in Drosophila has led...

Tepass, Ulrich; Tanentzapf­ , Guy; Ward, Robert; Fehon, Richard

2001-12-01

383

Studies of silicon p-n junction solar cells  

NASA Technical Reports Server (NTRS)

To provide theoretical support for investigating different ways to obtain high open-circuit voltages in p-n junction silicon solar cells, an analytical treatment of heavily doped transparent-emitter devices is presented that includes the effects of bandgap narrowing, Fermi-Dirac statistics, a doping concentration gradient, and a finite surface recombination velocity at the emitter surface. Topics covered include: (1) experimental determination of bandgap narrowing in the emitter of silicon p-n junction devices; (2) heavily doped transparent regions in junction solar cells, diodes, and transistors; (3) high-low-emitter solar cell; (4) determination of lifetimes and recombination currents in p-n junction solar cells; (5) MOS and oxide-charged-induced BSF solar cells; and (6) design of high efficiency solar cells for space and terrestrial applications.

Neugroschel, A.; Lindholm, F. A.

1979-01-01

384

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

E-print Network

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

Iglesias Cuervo, Jesus

2012-01-01

385

Polyamines regulate gap junction communication in connexin 43-expressing cells.  

PubMed Central

The control of cell-cell communication through gap junctions is thought to be crucial in normal tissue function and during various stages of tumorigenesis. However, few natural regulators of gap junctions have been found. We show here that increasing the activity of ornithine decarboxylase, or adding polyamines to the outside of cells, increases the level of gap junction communication between various epithelial cells. Conversely, reduction of ornithine decarboxylase activity decreases the level of gap junction communication. This regulation is dependent upon the expression of connexin 43 (Cx43 or Cxalpha1), which is a major connexin expressed in many different cell types, and involves an increase in Cx43 and its cellular re-distribution. PMID:11439099

Shore, L; McLean, P; Gilmour, S K; Hodgins, M B; Finbow, M E

2001-01-01

386

30 CFR 57.12007 - Junction box connection procedures.  

Code of Federal Regulations, 2011 CFR

...LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Electricity Surface and Underground § 57.12007 Junction box connection procedures. Trailing cable and power-cable...

2011-07-01

387

30 CFR 57.12007 - Junction box connection procedures.  

Code of Federal Regulations, 2010 CFR

...LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Electricity Surface and Underground § 57.12007 Junction box connection procedures. Trailing cable and power-cable...

2010-07-01

388

Non-synaptic transmission at autonomic neuroeffector junctions Geoffrey Burnstock *  

E-print Network

Neuroscience Centre, Royal Free and University College School of Medicine, Rowland Hill Street, London NW3 2PF during conduction of an impulse, although excitatory and inhibitory junction poten- tials are probably

Burnstock, Geoffrey

389

Balloon Photography of Earth Fissures Near Apache Junction  

NSDL National Science Digital Library

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

390

Experimental Realization of Josephson Junctions for an Atom SQUID  

NASA Astrophysics Data System (ADS)

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

Ryu, C.; Blackburn, P. W.; Blinova, A. A.; Boshier, M. G.

2013-11-01

391

Experimental realization of Josephson junctions for an atom SQUID.  

PubMed

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

Ryu, C; Blackburn, P W; Blinova, A A; Boshier, M G

2013-11-15

392

Laboratory instrumentation and techniques for characterizing multi-junction solar cells for space applications  

Microsoft Academic Search

Multi-junction solar cells are attractive for space applications because they can be designed to convert a larger fraction of AMO into electrical power at a lower cost than single-junction cells. The performance of multi-junction cells is much more sensitive to the spectral irradiance of the illuminating source than single-junction cells. The design of high efficiency multi-junction cells for space applications

James R. Woodyard

1995-01-01

393

RWGSCAT/CWGSCAT - RECTANGULAR AND CIRCULAR WAVEGUIDE JUNCTION SCATTERING PACKAGE  

NASA Technical Reports Server (NTRS)

Accurate computer modeling of passive circular or rectangular waveguide components is often required during the design phase for optimizing frequency response and/or determining the tolerance required on components in order to meet radio frequency specifications. RWGSCAT/CWGSCAT is capable of modeling both types of waveguide components. The Scattering Matrix Program for Circular Waveguide Junctions, CWGSCAT, computes the scattering matrix for a circular waveguide. This includes a dual mode horn and certain types of corrugated horns. RWGSCAT, Rectangular WaveGuide junction SCATtering program, solves for the scattering properties of a rectangular waveguide device, such as a smooth or corrugated rectangular horn, step transformer, or filter. RWGSCAT and CWGSCAT are also available separately as NPO-19091 and NPO-18708, respectively. Many circular waveguide devices can be represented either exactly or approximately as a series of circular waveguide sections which have a common center. In addition, smooth tapers and horns of arbitrary profile may be approximated by a series of small steps. Devices that may be analyzed in this fashion include a simple waveguide step discontinuity, such as that used in a dual mode horn, a stepped matching section, or a corrugated waveguide section with constant varying slot depth. CWGSCAT will accurately predict the reflection and transmission characteristics of such devices, taking into account higher order mode excitation if it occurs as well as multiple reflections and stored energy at each discontinuity. For large devices, with respect to a wavelength where many modes may propagate, the reflection and transmission properties may be required for a higher order mode or series of modes exciting the device. Such interactions are represented best by defining a scattering matrix for the device. The matrix can be determined by using mode matching at each discontinuity present. The results for individual discontinuities are then cascaded to get the matrix for the entire device. Frequently, rectangular waveguide components may be represented either exactly or approximately as a number of different size rectangular waveguides which are connected in series. RWGSCAT will model such devices and accurately predict the reflection and transmission characteristics, taking into account higher order (other than dominant TE 10) mode excitation if it occurs, as well as multiple reflections and stored energy at each discontinuity. For devices which are large with respect to the wavelength of operation, the characteristics of the device may be required for computing a higher order mode or a number of higher order modes exciting the device. Such interactions can be represented by defining a scattering matrix for each discontinuity in the device, and then cascading the individual scattering matrices in order to determine the scattering matrix for the overall device. The individual matrices are obtained using the mode matching method. RWGSCAT and CWGSCAT are written in FORTRAN 77 for IBM PC series and compatible computers running MS-DOS. They have been successfully compiled and implemented using Lahey FORTRAN 77 under MS-DOS. Sample MS-DOS executables and sample input data files are provided on the distribution media. RWGSCAT requires 377K of RAM for execution. CWGSCAT requires 355K of RAM for execution. The standard distribution medium for this program is a set of two 5.25 inch 360K MS-DOS format diskettes. The contents of the diskettes are compressed using the PKWARE archiving tools. The utility to unarchive the files, PKUNZIP.EXE, is included. An electronic copy of the documentation is included on the distribution medium in LaTEX format. RWGSCAT was developed in 1993. CWGSCAT was developed in 1987, and this version was released in 1991. RWGSCAT and CWGSCAT are copyrighted works with all copyrights vested in NASA.

Hoppe, D. J.

1994-01-01

394

Claudin-7 expressed on lateral membrane of rat epididymal epithelium does not form aberrant tight junction strands.  

PubMed

Claudins are integral membrane proteins at tight junctions (TJs) and form TJ strands. In the present study, we found that claudin-7 was localized along the entire lateral membranes of epididymal epithelium, including the apical junctional region throughout the epididymis, but claudin-8 was restricted to the apical junctional region. This finding raises the possibility that aberrant TJ strands may be formed on lateral membranes. Thus, we focused on examining whether TJ strands exist on lateral membranes of epididymal epithelium. Freeze-fracture electron microscopy showed that aberrant TJ strands were observed in only a few principal cells in all segments of the epididymis except for the initial segment, indicating that the occurrence of aberrant strands is very rare. Aberrant TJ strands were smooth and not subdivided into individual particles in the protoplasmic face, and complementary grooves in the extracellular face were almost free of particles. Aberrant TJ strands in the distal caput and corpus epididymis were accompanied by many vesicle-like structures but those in the proximal caput and cauda epididymis were not. These results suggest that most of claudin-7 in lateral membranes may exist in a nonpolymerized form and may play some different roles other than the formation of TJ strands, for example, in the formation of a pool of claudin proteins or in the reinforcement of cell adhesion. PMID:17853415

Inai, Tetsuichiro; Sengoku, Akihito; Hirose, Eiji; Iida, Hiroshi; Shibata, Yosaburo

2007-11-01

395

Gravitational radiation by cosmic strings in a junction  

SciTech Connect

The formalism for computing the gravitational power radiation from excitations on cosmic strings forming a junction is presented and applied to the simple case of co-planar strings at a junction when the excitations are generated along one string leg. The effects of polarization of the excitations and of the back-reaction of the gravitational radiation on the small scale structure of the strings are studied.

Brandenberger, R.; Karouby, J. [Physics Department, McGill University, Montreal, H3A 2T8 (Canada)] [Physics Department, McGill University, Montreal, H3A 2T8 (Canada); Firouzjahi, H. [School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of)] [School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); Khosravi, S., E-mail: firouz@ipm.ir [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of)

2009-01-15

396

Gravitational Radiation by Cosmic Strings in a Junction  

E-print Network

The formalism for computing the gravitational power radiation from excitations on cosmic strings forming a junction is presented and applied to the simple case of co-planar strings at a junction when the excitations are generated along one string leg. The effects of polarization of the excitations and of the back-reaction of the gravitational radiation on the small scale structure of the strings are studied.

Brandenberger, Robert; Karouby, Johanna; Khosravi, Shahram

2008-01-01

397

From Josephson junction metamaterials to tunable pseudo-cavities  

NASA Astrophysics Data System (ADS)

The scattering through a Josephson junction (JJ) interrupting a superconducting line is revisited including power leakage. We also discuss how to make tunable and broadband resonant mirrors by concatenating junctions. As an application, we show how to construct cavities using these mirrors, thus connecting two research fields: JJ quantum metamaterials and coupled-cavity arrays. We finish by discussing the first nonlinear corrections to the scattering and their measurable effects.

Zueco, D.; Fernández-Juez, C.; Yago, J.; Naether, U.; Peropadre, B.; García-Ripoll, J. J.; Mazo, J. J.

2013-07-01

398

Etching suspended superconducting tunnel junctions from a multilayer  

NASA Astrophysics Data System (ADS)

A method to fabricate large-area superconducting hybrid tunnel junctions with a suspended central normal metal part is presented. The samples are fabricated by combining photo-lithography and chemical etch of a superconductor—insulator—normal metal multilayer. The process involves few fabrication steps, is reliable and produces extremely high-quality tunnel junctions. Under an appropriate voltage bias, a significant electronic cooling is demonstrated. We analyze semi-quantitatively the thermal behavior of a typical device.

Nguyen, H. Q.; Pascal, L. M. A.; Peng, Z. H.; Buisson, O.; Gilles, B.; Winkelmann, C. B.; Courtois, H.

2012-06-01

399

The effects of connexin phosphorylation on gap junctional communication  

Microsoft Academic Search

Gap junctions are specialized membrane domains composed of collections of channels that directly connect neighboring cells providing for the cell-to-cell diffusion of small molecules, including ions, amino acids, nucleotides, and second messengers. Vertebrate gap junctions are composed of proteins encoded by the “connexin” gene family. In most cases examined, connexins are modified post-translationally by phosphorylation. Phosphorylation has been implicated in

Paul D. Lampe; Alan F. Lau

2004-01-01

400

Quantum statistical theory of semiconductor junctions in thermal equilibrium  

NASA Technical Reports Server (NTRS)

Free carrier and electric field distributions of one-dimensional semiconductor junctions are evaluated using a quantum mechanical phase-space distribution and its corresponding Boltzmann equation. Attention is given to quantum and exchange corrections in cases of high doping concentrations when carrier densities become degenerate. Quantitative differences between degenerate and classical junction characteristics, e.g., maximum electric field and built-in voltage and carrier concentration within the transition region, are evaluated numerically.

Von Roos, O.

1977-01-01

401

Solution-Processed Memristive Junctions Used in a Threshold Indicator  

Microsoft Academic Search

Inkjet-patterned memristive metal\\/oxide\\/metal structures were characterized to infer ionic and electronic transport parameters such as mobility and ion distribution. The conductance change with respect to voltage and time was measured for an individual crossbar junction and for junctions that are connected in series. It was found that continuous dopant redistribution during voltage scans led to a peak in conductance. The

Tse Nga Ng; Beverly Russo; Ana Claudia Arias

2011-01-01

402

Mos-oxide charge induced junction solar cells  

Microsoft Academic Search

It has been established in literature that MOS-Inversion Layer Solar Cells have characteristically better performance than conventional diffused junction solar cells, due to its shallow oxide charge induced junction, having very high collection efficiency because of the large electric field existing in the n-induced region; nature of the Si-SiOâ interface where surface recombination velocity is extremely low; and the near

A. K. Vaseashta; S. Kumari

1983-01-01

403

Prism-coupled light emission from tunnel junctions  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

404

Raman scattering at plasmonic junctions shorted by conductive molecular bridges.  

PubMed

Intensity spikes in Raman scattering, accompanied by switching between line spectra and band spectra, can be assigned to shorting the junction plasmon through molecular conductive bridges. This is demonstrated through Raman trajectories recorded at a plasmonic junction formed by a gold AFM tip in contact with a silver surface coated either with biphenyl-4,4'-dithiol or biphenyl-4-thiol. The fluctuations are absent in the monothiol. In effect, the making and breaking of chemical bonds is tracked. PMID:23534898

El-Khoury, Patrick Z; Hu, Dehong; Apkarian, V Ara; Hess, Wayne P

2013-04-10

405

UV to IR photon detection using superconducting tunnel junctions  

Microsoft Academic Search

Superconducting Tunnel Junctions have been investigated in the past as particle and X-ray detectors. We report here on results obtained illuminating Nb-Al-AlOx-Nb junctions with radiation covering the UV to IR (250 – 1100 nm) at 0.30 K. In the presence of continuous illumination, an increase of the subgap current is observed, while the change is found to be consistent with

N. Rando; A. Peacock; M. A. C. Perryman; P. Hübner; A. Dordrecht; P. Videler; J. Lumley

1993-01-01

406

Infrared Reflective and Transparent Inverted Metamorphic Triple Junction Solar Cells  

Microsoft Academic Search

The infrared (IR) portion of the solar spectrum with photon energies below the lowest bandgap in III-V multijunction photovoltaic devices does not contribute to electrical power and is typically ignored during solar cell design. In a three junction inverted metamorphic multijunction (IMM) solar cell with a 1.0 eV bottom junction, this infrared light makes up 16% of the total power

John F. Geisz; J. Scott Ward; Anna Duda; Waldo Olavarria; Lynn Gedvilas; Michelle Young; Mark W. Wanlass; Jeff Carapella; Sarah R. Kurtz; Daniel J. Friedman; Manuel J. Romero; Myles A. Steiner

2010-01-01

407

Magnetic anisotropy in strained manganite films and bicrystal junctions  

NASA Astrophysics Data System (ADS)

Transport and magnetic properties of La0.67Sr0.33MnO3 (LSMO) manganite thin films and bicrystal junctions were investigated. Epitaxial manganite films were grown on SrTiO3, LaAlO3, NdGaO3 (NGO), and (LaAlO3)0.3 + (Sr2AlTaO6)0.7 substrates, and their magnetic anisotropy were determined by two independent techniques of magnetic resonance spectroscopy. It was demonstrated that by using these techniques, a small (0.3%) anisotropy of crystal structure at the (110) surface plane of the orthorhombic NGO substrate leads to uniaxial magnetic anisotropy of the films in the plane of the substrate at least at the room temperature. It was found that on vicinal NGO substrates, the value of magnetic anisotropy strength can be varied in the range 100-200 Oe at T = 295 K by changing the substrate vicinal angle from 0° to 25°. Measurement of the magnetic anisotropy of manganite bicrystal junction demonstrated the presence of two ferromagnetic spin subsystems for both types of bicrystal boundaries with tilting of basal plane of manganite tilted bicrystal (TB-junction) and with rotation of crystallographic axes (RB-junction) used for comparison. The magnetoresistance of TB-junctions increases with decreasing temperature and the misorientation angle. Variation of bicrystal misorientation angle does not lead to change of misorientation of easy magnetic axes in the film parts forming TB-junction. Analysis of the voltage dependencies of bicrystal junction conductivity show that the low value of the magnetoresistance for the LSMO bicrystal junctions can be caused by two scattering mechanisms. The first one is the spin-flip of spin-polarized carriers due to the strong electron-electron interactions in a disordered layer at the bicrystal boundary at low temperatures and the second one is spin-flip by antiferromagnetic magnons at high temperatures.

Demidov, V. V.; Ovsyannikov, G. A.; Petrzhik, A. M.; Borisenko, I. V.; Shadrin, A. V.; Gunnarsson, R.

2013-04-01

408

Tectonic pattern of the Azores spreading centre and triple junction  

Microsoft Academic Search

The major tectonic elements of the Azores triple junction have been mapped using long-range side-scan sonar. The data enable the Mid-Atlantic Ridge axis to be located with a precision of a few kilometres. Major faults and other tectonic and volcanic elements of the ridge maintain their regional trend of 010° to 020° past the triple junction area. There is no

Roger Searle

1980-01-01

409

Finding the optimal lengths for three branches at a junction.  

PubMed

This paper presents an exact analytical solution to the problem of locating the junction point between three branches so that the sum of the total costs of the branches is minimized. When the cost per unit length of each branch is known the angles between each pair of branches can be deduced following reasoning first introduced to biology by Murray. Assuming the outer ends of each branch are fixed, the location of the junction and the length of each branch are then deduced using plane geometry and trigonometry. The model has applications in determining the optimal cost of a branch or branches at a junction. Comparing the optimal to the actual cost of a junction is a new way to compare cost models for goodness of fit to actual junction geometry. It is an unambiguous measure and is superior to comparing observed and optimal angles between each daughter and the parent branch. We present data for 199 junctions in the pulmonary arteries of two human lungs. For the branches at each junction we calculated the best fitting value of x from the relationship that flow alpha (radius)x. We found that the value of x determined whether a junction was best fitted by a surface, volume, drag or power minimization model. While economy of explanation casts doubt that four models operate simultaneously, we found that optimality may still operate, since the angle to the major daughter is less than the angle to the minor daughter. Perhaps optimality combined with a space filling branching pattern governs the branching geometry of the pulmonary artery. PMID:6645558

Woldenberg, M J; Horsfield, K

1983-09-21

410

Control of Spin-Triplet Josephson Junctions with Perpendicular Anisotropy  

NASA Astrophysics Data System (ADS)

We present recent work on S/F'/F/F''/S Josephson Junctions with the magnetic multilayer Ni/[Co/Ni]n as the central F layer [1]. This multilayer possesses strong intrinsic perpendicular (out-of-plane) anisotropy at Co and Ni thicknesses of a few monolayers. If a hard ferromagnet is used for F', and a softer ferromagnet is used for F'', both with magnetizations in plane, the direction of the F'' layer's magnetization is predicted to control the state of the junction [2]. We are fabricating such junctions with the goal of controllably switching the junction between the 0 and ? states. By integrating these junctions in a SQUID device, a measurement of the 0and ? state of the junction can be performed. We will report on our progress.[1] E.C. Gingrich, P. Quarterman, Y. Wang, R. Loloee, W.P. Pratt, and N.O. Birge, arXiv:1208.3118v1.[2] A.F. Volkov, F.S. Bergeret, and K.B. Efetov, Phys. Rev. Lett. 90, 117006 (2003).

Gingrich, Eric; Diesch, Simon; Pratt, William; Birge, Norman

2013-03-01

411

Foundations of Molecular Electronics — Charge Transport in Molecular Conduction Junctions  

NASA Astrophysics Data System (ADS)

The most fundamental structure involved in molecular electronics is a molecular transport junction, consisting of one (ideally) or more molecules extending between two electrodes. These junctions combine the fundamental process of intramolecular electron transfer with the mixing of molecular and continuum levels at the electrodes and the nonequilibrium process of voltage-driven currents. Much of this book is devoted to the complicated but significant behaviors that arise from this conjunction. This introductory chapter attempts to sketch some of the principles and also some of the unresolved issues that characterize molecular transport junctions. Sections 1.2 1.4 deal with fundamental ideas. These include an appropriate theoretical formulation of the conductance calculation in terms of non-equilibrium Green’s functions, the relationship between junction conductance and nonadiabatic electron transfer rates in the same molecular entities, and the role and magnitude of interactions between the dynamics of the transferring electronic charges and the nuclear degrees of freedom. Section 1.5 addresses some of the outstanding and difficult issues in understanding junction transport, including geometry and its change with voltage, the electrostatic profile under applied voltage, electronic structure models and their limitations, and fluctuations and switching phenomena in junctions.

Jortner, Joshua; Nitzan, Abraham; Ratner, Mark A.

412

Electric current in star junctions of molecular wires  

NASA Astrophysics Data System (ADS)

There is an enormous amount of literature on molecular-size circuits. However, no common regularities have ever been reported regarding the embedding of Y-like or, more generally, starlike molecular junctions into circuits. At the same time, connections of several wires are unavoidable components of any circuit. We show that in star junctions of N identical molecular wires, which are equally coupled to the feeding leads, the branched current is inversely proportional to N2. It is also proved that, independently of molecular structure, the minimal resistance that is associated with the terminal-to-terminal current through such junctions is equal to hN2/8e2. In words, it is divided by eight von Klitzing resistance times N2. These predictions rule the performance of quantum wire junctions and provide useful references for studies of complex multiterminal molecular devices. The current-voltage dependence predicted for the circuits that contain a star junction of molecular wires is compared with I-V characteristics of constructively similar junctions of conventional resistors, where the Ohm law prescribes the proportionality of branched current to 1/N. The newly derived basic formulas include the exact solution of Lippman-Schwinger equation for a general model of multiterminal, rigid (coherent) scatterer, and also, a new and general trace formula for multiterminal transmission.

Onipko, Alexander; Malysheva, Lyuba

2012-07-01

413

Symplekin, a novel type of tight junction plaque protein  

PubMed Central

Using a monoclonal antibody we have identified and cDNA-cloned a novel type of protein localized, by light and electron microscopy, to the plaque associated with the cytoplasmic face of the tight junction- containing zone (zonula occludens) of polar epithelial cells and of Sertoli cells of testis, but absent from the junctions of vascular endothelia. The approximately 3.7-kb mRNA encodes a polypeptide of 1142 amino acids (calculated molecular weight 126.5 kD, pI 6.25), for which the name "symplekin" (from Greek sigma upsilon mu pi lambda epsilon kappa epsilon iota, nu, to tie together, to weave, to be intertwined) is proposed. However, both the mRNA and the protein can also be detected in a wide range of cell types that do not form tight junctions or are even completely devoid of any stable cell contacts. Careful analyses have revealed that the protein occurs in all these diverse cells in the nucleoplasm, and only in those cells forming tight junctions is it recruited, partly but specifically, to the plaque structure of the zonula occludens. We discuss symplekin as a representative of a group of dual residence proteins which occur and probably function in the nucleus as well as in the plaques exclusive for either tight junctions, adherens junctions, or desmosomes. PMID:8769423

1996-01-01

414

Electronic Transport in Molecular Junction Based on C20 Cages  

NASA Astrophysics Data System (ADS)

Choosing closed-ended armchair (5, 5) single-wall carbon nanotubes (CCNTs) as electrodes, we investigate the electron transport properties across an all-carbon molecular junction consisting of C20 molecules suspended between two semi-infinite carbon nanotubes. It is shown that the conductances are quite sensitive to the number of C20 molecules between electrodes for both configuration CF1 and double-bonded models: the conductances of C20 dimers are markedly smaller than those of monomers. The physics is that incident electrons easily pass the C20 molecules and are predominantly scattered at the C20-C20 junctions. Moreover, we study the doping effect of such molecular junction by doping nitrogen atoms substitutionally. The bonding property of the molecular junction with configuration CF1 has been analysed by calculating the Mulliken atomic charges. Our results have revealed that the C atoms in N-doped junctions are more ionic than those in pure-carbon ones, leading to the fact that N-doped junctions have relatively large conductance.

Ouyang, Fang-Ping; Xu, Hui

2007-04-01

415

Egg Formation in Lepidoptera  

PubMed Central

Reproductive biology in the Twentieth Century produced comprehensive descriptions of the mechanisms of egg formation in most of the major orders of insects. While many general principles of ovarian development and physiology emerged, every order turned out to have a set of its own special motifs. Discovery of the lepidopteran motifs is summarized in this essay. The emphasis is on developmental mechanisms, beginning with the early growth and differentiation of female germ cells and ending, after many turns in morphogenesis, physiology and biosynthesis, with eggs that are filled with yolk and encased in chorions. Examples of uniquely lepidopteran traits include the cellular composition of ovarian follicles, the number of tubular ovarioles in which they mature, the functions of cell-to-cell junctional complexes in their maturation, their use of glycosaminoglycans to maintain intercellular patency during vitellogenesis, the role of proton and calcium pumps in their ion physiology, a separate postvitellogenic period of water and inorganic ion uptake, and the fine structure and protein composition of their chorions. Discovery of this combination of idiosyncracies was based on advances in the general concepts and techniques of cell and molecular biology and on insights borrowed from studies on other insects. The lepidopteran ovary in turn has contributed much to the understanding of egg formation in insects generally. PMID:20050770

Telfer, William H.

2009-01-01

416

Effects of furosemide on the neuromuscular junction.  

PubMed

These studies investigated the direct effects of furosemide on neuromuscular transmission using the in vitro rat phrenic nerve diaphragm and the in vivo at soleus nerve muscle preparations. Furosemide (10(-6)-10(-4)m) reduced the concentration of d-tubocurarine required to achieve 50% twitch tension depression in the indirectly stimulated rat diaphragm. Intraarterial injection of furosemide had a biphasic effect on the cat neuromuscular junction. At low doses (0.1-10.0 micrograms/kg) the drug had a depressant effect, reduced the force of muscle contraction, prevented nerve and muscle responses to NaF and dibutryl cyclic AMP, and intensified the neuromuscular blockade produced by d-tubocurarine and succinylcholine. In contrast, in higher doses (1-4 mg/kg) furosemide produced stimulus-bound repetitive neural activity, initiated neural activity, increased the force of muscle contraction, enhanced nerve and muscle responses to NaF and dibutyrl cyclic AMP, and antagonized d-tubocurarine and succinylcholine blockades. Furosemide had no effect on denervated preparations. High doses of furosemide inhibit non-competitively both the high- and low-affinity forms of the enzyme cyclic AMP phosphodiesterase in both soluble and particulate fractions of cat sciatic nerve. Thus, furosemide has direct effects on neuromuscular transmission, but the direction of these effects is dose-dependent. PMID:6291433

Scappaticci, K A; Ham, J A; Sohn, Y J; Miller, R D; Dretchen, K L

1982-11-01

417

Aeroacoustics of T-junction merging flow.  

PubMed

This paper reports a numerical study of the aeroacoustics of merging flow at T-junction. The primary focus is to elucidate the acoustic generation by the flow unsteadiness. The study is conducted by performing direct aeroacoustic simulation approach, which solves the unsteady compressible Navier-Stokes equations and the perfect gas equation of state simultaneously using the conservation element and solution element method. For practical flows, the Reynolds number based on duct width is usually quite high (>10(5)). In order to properly account for the effects of flow turbulence, a large eddy simulation methodology together with a wall modeling derived from the classical logarithm wall law is adopted. The numerical simulations are performed in two dimensions and the acoustic generation physics at different ratios of side-branch to main duct flow velocities VR (=0.5,0.67,1.0,2.0) are studied. Both the levels of unsteady interactions of merging flow structures and the efficiency of acoustic generation are observed to increase with VR. Based on Curle's analogy, the major acoustic source is found to be the fluctuating wall pressure induced by the flow unsteadiness occurred in the downstream branch. A scaling between the wall fluctuating force and the efficiency of the acoustic generation is also derived. PMID:23363089

Lam, G C Y; Leung, R C K; Tang, S K

2013-02-01

418

Etching Magnetic Tunnel Junction with Metal Etchers  

NASA Astrophysics Data System (ADS)

Etch performances of inductory-coupled plasma (ICP) metal etchers with several gas systems are examined under constant ion energy condition to evaluate extendibility to the 300 mm wafer magnetic tunnel junction (MTJ) etch process. The ICP-Ar sputter etch affects little on magnetic properties, and shows about the same magnetoresistive (MR) ratio with conventional Ar ion milling. Major issue is the electrical short by redeposition. The etch uniformity over the wafer and precise etch end-point detection are important. The Cl2 addition to the ICP-Ar etch plasma shows serious pattern deformation and degradation of loop offset (Hoff). Methanol (Me-OH) etch shows slightly lower MR-ratio due to material degradation. However, better Hoff is observed probably due to the ion protection effect by thin carbon layer over the etched surface. Dilution of Me-OH with Ar improves MR ratio. Ar/Me-OH and ICP-Ar etch processes would be the candidate for 300 mm process at present.

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

2010-08-01

419

Ferroelectric tunnel junctions with graphene electrodes  

NASA Astrophysics Data System (ADS)

Polarization-driven resistive switching in ferroelectric tunnel junctions (FTJs)—structures composed of two electrodes separated by an ultrathin ferroelectric barrier—offers new physics and materials functionalities, as well as exciting opportunities for the next generation of non-volatile memories and logic devices. Performance of FTJs is highly sensitive to the electrical boundary conditions, which can be controlled by electrode material and/or interface engineering. Here, we demonstrate the use of graphene as electrodes in FTJs that allows control of interface properties for significant enhancement of device performance. Ferroelectric polarization stability and resistive switching are strongly affected by a molecular layer at the graphene/BaTiO3 interface. For the FTJ with the interfacial ammonia layer we find an enhanced tunnelling electroresistance (TER) effect of 6 × 105%. The obtained results demonstrate a new approach based on using graphene electrodes for interface-facilitated polarization stability and enhancement of the TER effect, which can be exploited in the FTJ-based devices.

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

2014-11-01

420

Temporal order judgments activate temporal parietal junction.  

PubMed

Perceptual temporal order judgments require an individual to determine the relative timing of two spatially separate events. Here we reveal the brain regions involved with this task. We had participants observe perceptually identical visual stimuli while conducting two different tasks: discriminating temporal order or discriminating spatial properties. By contrasting the functional magnetic resonance imaging signals during these tasks, we were able to isolate regions specifically engaged by each task. Participants observed two briefly presented rectangles. In one task, participants were instructed to report which appeared first, and, in the other, they were requested to report which rectangle was squarer. A potential confound of this study is that the temporal order judgment (TOJ) task required processing of brief events (onsets), whereas the shape task did not require temporal selectivity. To address this, we conducted a second study in which both tasks required discriminating brief events concurrent with the object onsets. The stimuli were similar to the first experiment, except a gray line was briefly superimposed on each rectangle at onset. Participants reported either which rectangle appeared first (TOJ) or which rectangle had a slightly wider gray line (shape). The first study found that the TOJ task resulted in greater bilateral activation of the temporal parietal junction (TPJ). The second revealed TOJ activation in the TPJ of the left hemisphere. This suggests that TPJ activation increases when we need to temporally sequence information. This finding supports the notion that the TPJ may be a crucial component of the "when" pathway. PMID:19279255

Davis, Ben; Christie, John; Rorden, Christopher

2009-03-11

421

Temporal Order Judgments Activate Temporal Parietal Junction  

PubMed Central

Perceptual temporal order judgments require an individual to determine the relative timing of two spatially separate events. Here we reveal the brain regions involved with this task. We had participants observe perceptually identical visual stimuli while conducting two different tasks: discriminating temporal order or discriminating spatial properties. By contrasting the functional magnetic resonance imaging signals during these tasks, we were able to isolate regions specifically engaged by each task. Participants observed two briefly presented rectangles. In one task, participants were instructed to report which appeared first, and, in the other, they were requested to report which rectangle was squarer. A potential confound of this study is that the temporal order judgment (TOJ) task required processing of brief events (onsets), whereas the shape task did not require temporal selectivity. To address this, we conducted a second study in which both tasks required discriminating brief events concurrent with the object onsets. The stimuli were similar to the first experiment, except a gray line was briefly superimposed on each rectangle at onset. Participants reported either which rectangle appeared first (TOJ) or which rectangle had a slightly wider gray line (shape). The first study found that the TOJ task resulted in greater bilateral activation of the temporal parietal junction (TPJ). The second revealed TOJ activation in the TPJ of the left hemisphere. This suggests that TPJ activation increases when we need to temporally sequence information. This finding supports the notion that the TPJ may be a crucial component of the “when” pathway. PMID:19279255

Davis, Ben; Christie, John

2009-01-01

422

Homeostatic plasticity at the Drosophila neuromuscular junction.  

PubMed

In biology, homeostasis refers to how cells maintain appropriate levels of activity. This concept underlies a balancing act in the nervous system. Synapses require flexibility (i.e. plasticity) to adjust to environmental challenges. Yet there must also exist regulatory mechanisms that constrain activity within appropriate physiological ranges. An abundance of evidence suggests that homeostatic regulation is critical in this regard. In recent years, important progress has been made toward identifying molecules and signaling processes required for homeostatic forms of neuroplasticity. The Drosophila melanogaster third instar larval neuromuscular junction (NMJ) has been an important experimental system in this effort. Drosophila neuroscientists combine genetics, pharmacology, electrophysiology, imaging, and a variety of molecular techniques to understand how homeostatic signaling mechanisms take shape at the synapse. At the NMJ, homeostatic signaling mechanisms couple retrograde (muscle-to-nerve) signaling with changes in presynaptic calcium influx, changes in the dynamics of the readily releasable vesicle pool, and ultimately, changes in presynaptic neurotransmitter release. Roles in these processes have been demonstrated for several molecules and signaling systems discussed here. This review focuses primarily on electrophysiological studies or data. In particular, attention is devoted to understanding what happens when NMJ function is challenged (usually through glutamate receptor inhibition) and the resulting homeostatic responses. A significant area of study not covered in this review, for the sake of simplicity, is the homeostatic control of synapse growth, which naturally, could also impinge upon synapse function in myriad ways. This article is part of the Special Issue entitled 'Homeostatic Synaptic Plasticity'. PMID:23806804

Frank, C Andrew

2014-03-01

423

Tunneling in Heavy-Fermion Junctions  

NASA Astrophysics Data System (ADS)

In this paper I review recent theoretical and experimental advances in understanding of tunneling processes between normal metals and metals containing electrons which occupy partially filled f-orbitals. In heavy-fermion materials the effective mass of the quasiparticles far exceeds the bare electron mass due to strong hybridization between conduction and f-orbital states. Kondo lattices form a class of heavy-fermion systems in which an average occupation number of f-electron states is close to an integer. Therefore, the tunneling into a Kondo lattice necessarily involves co-tunneling process of a tip electron into an f-electron state of a Kondo lattice. This co-tunneling process is manifested in the Fano-lineshape of differential conductance as a function of an applied voltage, which has been routinely observed in recent experiments on various Kondo lattice systems. To illustrate these ideas, I discuss the problem of the tunneling junction when the single particle states in the tip are also a product of hybridization between conduction and f-states, i.e., tunneling between two heavy-fermion materials.

Dzero, Maxim

2014-06-01

424

Age-associated alterations of neuromuscular junction  

PubMed Central

Age-related loss of muscle mass and function greatly affects quality of life in the elderly population. Several hypotheses have been proposed but accumulating evidence point to alterations in neuromuscular system during aging as a key event that leads to functional denervation, muscle wasting, and weakness. Over the past few decades, age-associated degeneration of the neuromuscular junction (NMJ) and its components have been well documented. With advancing age, pre-terminal portions of motor axons exhibit regions of abnormal thinning, distension, and sprouting whereas postsynaptic endplates decrease in size, reduce in number, length, and density of postsynaptic folds. Although the exact underlying mechanisms are still lacking, recent studies provided direct evidence that age-associated increase in oxidative stress plays a crucial role in NMJ degeneration and progression of sarcopenia. Homozygous deletion of an important antioxidant enzyme, Cu,Zn superoxide dismutase (CuZnSOD, SOD1) leads to acceleration of age-dependent muscle atrophy, with a significant NMJ degeneration similar to that seen in old wild type sarcopenic animals. In this short review, we briefly summarize the current understanding of some of the cellular and molecular changes in the NMJ during aging and suggest a role for oxidative stress and mitochondrial dysfunction in age-related changes in the maintenance of neuromuscular innervation. PMID:20854887

Jang, Youngmok C.; Van Remmen, Holly

2010-01-01

425

A Three-Isocenter Jagged-Junction IMRT Approach for Craniospinal Irradiation Without Beam Edge Matching for Field Junctions  

SciTech Connect

Purpose: Traditionally craniospinal irradiation treats the central nervous system using two or three adjacent field sets. We propose a technique using a three-isocenter intensity-modulated radiotherapy (IMRT) plan (jagged-junction IMRT) which overcomes problems associated with field junctions and beam edge matching and improves planning and treatment setup efficiencies with homogenous target dose distribution. Methods and Materials: Treatments for 3 patients with a prescription of 36 Gy in 20 fractions were retrospectively planned with jagged-junction IMRT and compared to conventional treatment plans. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. The plan used three field sets, each with a unique isocenter. One field set with seven fields treated the cranium. Two field sets treated the spine, each set using three fields. Fields from adjacent sets were overlapped, and the optimization process smoothly integrated the dose inside the overlapped junction. Results: For jagged-junction IMRT plans vs. conventional technique, the average homogeneity index equaled 0.08 {+-} 0.01 vs. 0.12 {+-} 0.02, respectively, and conformity number equaled 0.79 {+-} 0.01 vs. 0.47 {+-} 0.12, respectively. The 95% isodose surface covered (99.5 {+-} 0.3)% of the PTV vs. (98.1 {+-} 2.0)%, respectively. Both jagged-junction IMRT plans and the conventional plans had good sparing of organs at risk. Conclusions: Jagged-junction IMRT planning provided good dose homogeneity and conformity to the target while maintaining a low dose to organs at risk. Results from jagged-junction IMRT plans were better than or equivalent to those from the conventional technique. Jagged-junction IMRT optimization smoothly distributed dose in the junction between field sets. Because there was no beam matching, this treatment technique is less likely to produce hot or cold spots at the junction, in contrast to conventional techniques. The planning process is also simplified as only one IMRT plan is required for the entire target volume.

Cao, Fred, E-mail: fcao@bccancer.bc.ca [Department of Medical Physics, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada)] [Department of Medical Physics, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada); Ramaseshan, Ramani; Corns, Robert; Harrop, Sheryl [Department of Medical Physics, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada)] [Department of Medical Physics, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada); Nuraney, Nimet; Steiner, Peter; Aldridge, Stephanie [Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada)] [Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada); Liu, Mitchell; Carolan, Hannah [Department of Radiation Oncology, Vancouver Centre, BC Cancer Agency, Vancouver, British Columbia (Canada)] [Department of Radiation Oncology, Vancouver Centre, BC Cancer Agency, Vancouver, British Columbia (Canada); Agranovich, Alex; Karvat, Anand [Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada)] [Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada)

2012-11-01

426

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

SciTech Connect

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

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

2011-12-01

427

Regulation of vascular endothelial junction stability and remodeling through Rap1-Rasip1 signaling.  

PubMed

The ability of blood vessels to sense and respond to stimuli such as fluid flow, shear stress, and trafficking of immune cells is critical to the proper function of the vascular system. Endothelial cells constantly remodel their cell-cell junctions and the underlying cytoskeletal network in response to these exogenous signals. This remodeling, which depends on regulation of the linkage between actin and integral junction proteins, is controlled by a complex signaling network consisting of small G proteins and their various downstream effectors. In this commentary, we summarize recent developments in understanding the small G protein RAP1 and its effector RASIP1 as critical mediators of endothelial junction stabilization, and the relationship between RAP1 effectors and modulation of different subsets of endothelial junctions.   The vasculature is a dynamic organ that is constantly exposed to a variety of signaling stimuli and mechanical stresses. In embryogenesis, nascent blood vessels form via a process termed vasculogenesis, wherein mesodermally derived endothelial precursor cells aggregate into cords, which subsequently form a lumen that permits trafficking of plasma and erythrocytes. (1)(,) (2) Angiogenesis occurs after establishment of this primitive vascular network, where new vessels sprout from existing vessels, migrate into newly expanded tissues, and anastomose to form a functional and complex circulatory network. (1)(,) (2) In the mouse, this process occurs through the second half of embryogenesis and into postnatal development in some tissues, such as the developing retinal vasculature. (3) Further, angiogenesis occurs in a variety of pathological conditions, such as diabetic retinopathy, age-related macular degeneration, inflammatory diseases such as rheumatoid arthritis, wound healing, and tumor growth. (1)(,) (2)(,) (4) Both vasculogenesis and angiogenesis are driven through signaling by vascular endothelial growth factor (VEGF), and therapeutic agents targeting this pathway have shown efficacy in a number of diseases. (5)(-) (9) Blood vessels must have a sufficient degree of integrity so as to not allow indiscriminate leak of plasma proteins and blood cells into the underlying tissue. However, vessels must be able to sense their environment, respond to local conditions, and mediate the regulated passage of protein, fluid, and cells. For example, endothelial cells are the primary point of attachment for immune cells leaving the blood stream and entering tissue, and leukocytes subsequently migrate either through the endothelial cell body itself (the transcellular route), or through transient disassembly of cell-cell junctions (the paracellular route). (10) Precise regulation of endothelial junctions is critical to the proper maintenance of vascular integrity and related processes, and disruption of vascular cell-cell contacts is an underlying cause or contributor to numerous pathologies such as cerebral cavernous malformations (CCM) and hereditary hemorrhagic telangiectasia (HHT). (11)(-) (13) Understanding the basic mechanisms of endothelial junction formation and maintenance will therefore lead to a greater chance of success of therapeutic intervention in these pathologic conditions, especially in instances where targeting of VEGF signaling is insufficient to resolve vascular abnormalities. PMID:24622510

Wilson, Christopher W; Ye, Weilan

2014-01-01

428

Microstructure of Josephson junctions: Effect on supercurrent transport in YBCO grain boundary and barrier layer junctions  

SciTech Connect

The electric transport of high-temperature superconductors, such as YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} (YBCO), can be strongly restricted by the presence of high-angle grain boundaries (GB). This weak-link behavior is governed by the macroscopic GB geometry and the microscopic grain boundary structure and composition at the atomic level. Whereas grain boundaries present a considerable impediment to high current applications of high T{sub c} materials, there is considerable commercial interest in exploiting the weak-link-nature of grain boundaries for the design of microelectronic devices, such as superconducting quantum interference devices (SQUIDs). The Josephson junctions which form the basis of this technology can also be formed by introducing artificial barriers into the superconductor. The authors have examined both types of Josephson junctions by EM techniques in an effort to understand the connection between microstructure/chemistry and electrical transport properties. This knowledge is a valuable resource for the design and production of improved devices.

Merkle, K.L.; Huang, Y.

1998-01-01

429

Cost-Effective 28-nm LSTP CMOS using gate-first metal gate\\/high-k technology  

Microsoft Academic Search

Metal gate\\/high-k CMOS technology for 28-nm node low power and low standby power application is demonstrated. A gate-first single metal\\/high-k gate stack has been employed together with leading-edge isolation, ultra-shallow junction, and stress engineering technologies. High density and high performance device is provided with least process cost increase.

T. Tomimatsu; Y. Goto; H. Kato; M. Amma; M. Igarashi; Y. Kusakabe; M. Takeuchi; S. Ohbayashi; S. Sakashita; T. Kawahara; M. Mizutani; M. Inoue; M. Sawada; Y. Kawasaki; S. Yamanari; Y. Miyagawa; Y. Takeshima; Y. Yamamoto; S. Endo; T. Hayashi; Y. Nishida; K. Horita; T. Yamashita; H. Oda; K. Tsukamoto; Y. Inoue; H. Fujimoto; Y. Sato; K. Yamashita; R. Mitsuhashi; S. Matsuyama; Y. Moriyama; K. Nakanishi; T. Noda; Y. Sahara; N. Koike; J. Hirase; T. Yamada; H. Ogawa; M. Ogura

2009-01-01

430

Transient behavior in Pt/Nb-doped SrTiO3 Schottky junctions  

NASA Astrophysics Data System (ADS)

We investigated the transient behavior of Pt/Nb-doped SrTiO3 Schottky junctions that exhibit rectifying and hysteric I-V characteristics. We found that regardless of the junction resistance state, the junction under the bias shows the relaxation behavior over 104 s while the behavior is strongly dependent on the junction resistance state. Detailed investigation of the time dependence of the current and the capacitance of the junctions indicates that the junctions have the inhomogeneous Schottky barrier heights and depletion layer widths while the mean junction profile remains unchanged regardless of the junction resistance state. Given the experimental results, we attribute the observed transient behavior to time-dependent changes in the population of electrons trapped in the local conduction regions under the bias, which play an important role in determining the resistance state of Pt/Nb-doped SrTiO3 junction.

Kan, Daisuke; Shimakawa, Yuichi

2013-09-01

431

Microtubules are required for efficient epithelial tight junction homeostasis and restoration.  

PubMed

Epithelial tight junctions are critical for creating a barrier yet allowing paracellular transport. Although it is well established that the actin cytoskeleton is critical for preserving the dynamic organization of the tight junction and maintaining normal tight junction protein recycling, contributions of microtubules to tight junction organization and function remain undefined. The aim of this study is to determine the role of microtubules in tight junction homeostasis and restoration. Our data demonstrate that occludin traffics on microtubules and that microtubule disruption perturbs tight junction structure and function. Microtubules are also shown to be required for restoring barrier function following Ca(2+) chelation and repletion. These processes are mediated by proteins participating in microtubule minus-end-directed trafficking but not plus-end-directed trafficking. These studies show that microtubules participate in the preservation of epithelial tight junction structure and function and play a vital role in tight junction restoration, thus expanding our understanding of the regulation of tight junction physiology. PMID:24920678

Glotfelty, Lila G; Zahs, Anita; Iancu, Catalin; Shen, Le; Hecht, Gail A

2014-08-01

432

Na-K-ATPase regulates tight junction permeability through occludin phosphorylation in pancreatic epithelial cells.  

PubMed

Tight junctions are crucial for maintaining the polarity and vectorial transport functions of epithelial cells. We and others have shown that Na-K-ATPase plays a key role in the organization and permeability of tight junctions in mammalian cells and analogous septate junctions in Drosophila. However, the mechanism by which Na-K-ATPase modulates tight junctions is not known. In this study, using a well-differentiated human pancreatic epithelial cell line HPAF-II, we demonstrate that Na-K-ATPase is present at the apical junctions and forms a complex with protein phosphatase-2A, a protein known to be present at tight junctions. Inhibition of Na-K-ATPase ion transport function reduced protein phosphatase-2A activity, hyperphosphorylated occludin, induced rearrangement of tight junction strands, and increased permeability of tight junctions to ionic and nonionic solutes. These data suggest that Na-K-ATPase is required for controlling the tight junction gate function. PMID:16959951

Rajasekaran, Sigrid A; Barwe, Sonali P; Gopal, Jegan; Ryazantsev, Sergey; Schneeberger, Eveline E; Rajasekaran, Ayyappan K

2007-01-01

433

Regulation of gap junction function and Connexin 43 expression by cytochrome P450 oxidoreductase (CYPOR)  

SciTech Connect

Highlights: {yields} Humans with severe forms of cytochrome P450 oxidoreductase (CYPOR) mutations show bone defects as observed in Antley-Bixler Syndrome. {yields} First report showing knockdown of CYPOR in osteoblasts decreased Connexin 43 (Cx43) protein levels. Cx43 is known to play an important role in bone modeling. {yields} Knockdown of CYPOR decreased Gap Junctional Intercellular Communication and hemichannel activity. {yields} Knockdown of CYPOR decreased Cx43 in mouse primary calvarial osteoblasts. {yields} Decreased Cx43 expression was observed at the transcriptional level. -- Abstract: Cytochrome P450 oxidoreductase (CYPOR) is a microsomal electron-transferring enzyme containing both FAD and FMN as co-factors, which provides the reducing equivalents to various redox partners, such as cytochromes P450 (CYPs), heme oxygenase (HO), cytochrome b{sub 5} and squalene monooxygenase. Human patients with severe forms of CYPOR mutation show bone defects such as cranio- and humeroradial synostoses and long bone fractures, known as Antley-Bixler-like Syndrome (ABS). To elucidate the role of CYPOR in bone, we knocked-down CYPOR in multiple osteoblast cell lines using RNAi technology. In this study, knock-down of CYPOR decreased the expression of Connexin 43 (Cx43), known to play a critical role in bone formation, modeling, and remodeling. Knock-down of CYPOR also decreased Gap Junction Intercellular Communication (GJIC) and hemichannel activity. Promoter luciferase assays revealed that the decrease in expression of Cx43 in CYPOR knock-down cells was due to transcriptional repression. Primary osteoblasts isolated from bone specific Por knock-down mice calvariae confirmed the findings in the cell lines. Taken together, our study provides novel insights into the regulation of gap junction function by CYPOR and suggests that Cx43 may play an important role(s) in CYPOR-mediated bone defects seen in patients.

Polusani, Srikanth R.; Kar, Rekha; Riquelme, Manuel A.; Masters, Bettie Sue [The University of Texas Health Science Center at San Antonio, Department of Biochemistry, San Antonio, TX 78229 (United States)] [The University of Texas Health Science Center at San Antonio, Department of Biochemistry, San Antonio, TX 78229 (United States); Panda, Satya P., E-mail: panda@uthscsa.edu [The University of Texas Health Science Center at San Antonio, Department of Biochemistry, San Antonio, TX 78229 (United States)

2011-08-05

434

Long-range gap junctional signaling controls oncogene-mediated tumorigenesis in Xenopus laevis embryos  

PubMed Central

In addition to the immediate microenvironment, long-range signaling may be an important component of cancer. Molecular-genetic analyses have implicated gap junctions—key mediators of cell-cell communication—in carcinogenesis. We recently showed that the resting voltage potential of distant cell groups is a key determinant of metastatic transformation and tumor induction. Here, we show in the Xenopus laevis model that gap junctional communication (GJC) is a modulator of the long-range bioelectric signaling that regulates tumor formation. Genetic disruption of GJC taking place within tumors, within remote host tissues, or between the host and tumors significantly lowers the incidence of tumors induced by KRAS mutations. The most pronounced suppression of tumor incidence was observed upon GJC disruption taking place farther away from oncogene-expressing cells, revealing a role for GJC in distant cells in the control of tumor growth. In contrast, enhanced GJC communication through the overexpression of wild-type connexin Cx26 increased tumor incidence. Our data confirm a role for GJC in tumorigenesis, and reveal that this effect is non-local. Based on these results and on published data on movement of ions through GJs, we present a quantitative model linking the GJC coupling and bioelectrical state of cells to the ability of oncogenes to initiate tumorigenesis. When integrated with data on endogenous bioelectric signaling during left-right patterning, the model predicts differential tumor incidence outcomes depending on the spatial configurations of gap junction paths relative to tumor location and major anatomical body axes. Testing these predictions, we found that the strongest influence of GJ modulation on tumor suppression by hyperpolarization occurred along the embryonic left-right axis. Together, these data reveal new, long-range aspects of cancer control by the host's physiological parameters. PMID:25646081

Chernet, Brook T.; Fields, Chris; Levin, Michael

2015-01-01

435

Charge transfer in tunnel-junction arrays  

NASA Astrophysics Data System (ADS)

Numerical modeling was used to study charge transfer in tunnel junction arrays. The effects of various configurations of background charge were considered, with the ultimate goal of making predictions about the possibility of device design. First the uniform (no background charge) arrays were considered. In this case solitonantisoliton avalanches were observed. Though the time duration of any avalanche, and the total charge DeltaQ = ne transferred across the array during the avalanche, are always finite, in arrays with length N larger than certain critical value Lc and large width M >> f(N), the avalanche magnitude n may be exponentially large, resulting in particular in a giant increase of shot noise. Next a special distribution of background charge was found, such that the array's Coulomb blockade is completely suppressed and shot noise is reduced substantially at low applied voltages. In particular the Fano factor F can approach the minimum value Fmin = 1/N << 1 (where N is the array length). Finally, the effects of the fully random q = [-e/2; + e/2] background charge were studied. Density of states at zero energy was found to have a dramatically different dependence on the array size in 1D and 2D. Also, in 2D systems a soft Coulomb gap was observed, whit DoS value at low energy diminishing rapidly with the array size. The effects of background charge on shot noise were also studied. At zero temperature and low current in 2D systems a strong increase in shot noise was observed, while addition of moderately low (T < eVt/N) temperature suppresses the noise. Results are discussed in the context of their possible application to single-electron devices.

Kaplan, Daniel M. R.

436

Silicon-based molecular switch junctions  

E-print Network

In contrast to the static operations of conventional semiconductor devices, the dynamic conformational freedom in molecular devices opens up the possibility of using molecules as new types of devices such as a molecular conformational switch or for molecular data storage. Bistable molecules, with e.g. two stable cis and trans isomeric configurations, could provide, once clamped between two electrodes, a switching phenomenon in the nonequilibrium current response. Here, we model molecular switch junctions formed at silicon contacts and demonstrate the potential of tunable molecular switches in electrode/molecule/electrode configurations. Using the non equilibrium Green function approach implemented with the density-functional-based tight-binding theory, a series of properties such as electron transmissions, I-V characteristics in the different isomer-conformations, and potential energy surfaces as a function of the reaction coordinates along the trans to cis transition were calculated. Furthermore, in order to investigate stability of molecular switches in ambient conditions, molecular dynamics (MD) simulations at room temperature were performed and time- dependent fluctuations of the conductance along the MD pathways were calculated. Our numerical results show that the transmission spectra of the cis isomers are more conductive than trans counterparts inside the bias window for all two model molecules. The current-voltage characteristics consequently show the same trends. Additionally, the calculations of time-dependent transmission fluctuations along the MD pathways have shown that the transmission in cis isomers is always significantly larger than that of trans counterparts showing that molecular switches can be expected to work as robust molecular switching components.

Daijiro Nozaki; Gianaurelio Cuniberti

2009-07-01

437

Elongated nanostructures for radial junction solar cells.  

PubMed

In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented. PMID:24088584

Kuang, Yinghuan; Vece, Marcel Di; Rath, Jatindra K; Dijk, Lourens van; Schropp, Ruud E I

2013-10-01

438

Reciprocal influence of connexins and apical junction proteins on their expressions and functions  

PubMed Central

Membranes of adjacent cells form intercellular junctional complexes to mechanically anchor neighbour cells (anchoring junctions), to seal the paracellular space and to prevent diffusion of integral proteins within the plasma membrane (tight junctions) and to allow cell-to-cell diffusion of small ions and molecules (gap junctions). These different types of specialised plasma membrane microdomains, sharing common adaptor molecules, particularly zonula occludens proteins, frequently present intermingled relationships where the different proteins co-assemble into macromolecular complexes and their expressions are co-ordinately regulated. Proteins forming gap junction channels (connexins, particularly) and proteins fulfilling cell attachment or forming tight junction strands mutually influence expression and functions of one another. PMID:19046940

Derangeon, Mickaël; Spray, David C.; Bourmeyster, Nicolas; Sarrouilhe, Denis; Hervé, Jean-Claude

2009-01-01

439

Measure Guideline: Optimizing the Configuration of Flexible Duct Junction Boxes  

SciTech Connect

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

Beach, R.; Burdick, A.

2014-03-01

440

PN junction fabrication of solar cells and integration with metamaterials  

NASA Astrophysics Data System (ADS)

Silicon is the primary material used for the fabrication of solar cells and it is responsible for about 40% of the cost. Metamaterials show promise in enhancing the performance of silicon solar cells thus, improving the efficiency. Here we report on the fabrication of a broadband, antireflective, conductive metamaterial capable of channeling light into a solar cell. As a precursor to making the metamaterial, standard p-n junctions were fabricated. Conventional phosphorus oxychloride (POCl3) furnace diffusion was used to create the p-n junction. When the p-n junction was forward biased, the measured current exhibited a diode characteristic. The measured photocurrent response yielded an open circuit voltage for the p-n junction at 0.48 VDC. The metamaterial film was fabricated, placed atop the p-n junction and characterized. Initial tests showed that the metamaterial antireflective properties were on par with those of standard industrial single-layer silicon nitride coatings. Further testing is being performed to assess the full optical and electrical performance of the metamaterial film.

Enemuo, Amarachukwu; Crouse, David T.; Crouse, Michael

2011-05-01