Science.gov

Sample records for forms potent contact

  1. Cytochrome P450-mediated activation of the fragrance compound geraniol forms potent contact allergens

    SciTech Connect

    Hagvall, Lina; Baron, Jens Malte; Boerje, Anna; Weidolf, Lars; Merk, Hans; Karlberg, Ann-Therese

    2008-12-01

    Contact sensitization is caused by low molecular weight compounds which penetrate the skin and bind to protein. In many cases, these compounds are activated to reactive species, either by autoxidation on exposure to air or by metabolic activation in the skin. Geraniol, a widely used fragrance chemical, is considered to be a weak allergen, although its chemical structure does not indicate it to be a contact sensitizer. We have shown that geraniol autoxidizes and forms allergenic oxidation products. In the literature, it is suggested but not shown that geraniol could be metabolically activated to geranial. Previously, a skin-like CYP cocktail consisting of cutaneous CYP isoenzymes, was developed as a model system to study cutaneous metabolism. In the present study, we used this system to investigate CYP-mediated activation of geraniol. In incubations with the skin-like CYP cocktail, geranial, neral, 2,3-epoxygeraniol, 6,7-epoxygeraniol and 6,7-epoxygeranial were identified. Geranial was the main metabolite formed followed by 6,7-epoxygeraniol. The allergenic activities of the identified metabolites were determined in the murine local lymph node assay (LLNA). Geranial, neral and 6,7-epoxygeraniol were shown to be moderate sensitizers, and 6,7-epoxygeranial a strong sensitizer. Of the isoenzymes studied, CYP2B6, CYP1A1 and CYP3A5 showed high activities. It is likely that CYP1A1 and CYP3A5 are mainly responsible for the metabolic activation of geraniol in the skin, as they are expressed constitutively at significantly higher levels than CYP2B6. Thus, geraniol is activated through both autoxidation and metabolism. The allergens geranial and neral are formed via both oxidation mechanisms, thereby playing a large role in the sensitization to geraniol.

  2. Method for forming metal contacts

    DOEpatents

    Reddington, Erik; Sutter, Thomas C; Bu, Lujia; Cannon, Alexandra; Habas, Susan E; Curtis, Calvin J; Miedaner, Alexander; Ginley, David S; Van Hest, Marinus Franciscus Antonius Maria

    2013-09-17

    Methods of forming metal contacts with metal inks in the manufacture of photovoltaic devices are disclosed. The metal inks are selectively deposited on semiconductor coatings by inkjet and aerosol apparatus. The composite is heated to selective temperatures where the metal inks burn through the coating to form an electrical contact with the semiconductor. Metal layers are then deposited on the electrical contacts by light induced or light assisted plating.

  3. Front contact solar cell with formed emitter

    SciTech Connect

    Cousins, Peter John

    2014-11-04

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  4. Front contact solar cell with formed emitter

    DOEpatents

    Cousins, Peter John

    2012-07-17

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  5. Pion form factor from a contact interaction

    SciTech Connect

    Gutierrez-Guerrero, L. X.; Bashir, A.; Cloeet, I. C.; Roberts, C. D.

    2010-06-15

    In a Poincare-covariant vector-boson-exchange theory, the pion possesses components of pseudovector origin, which materially influence its observable properties. For a range of such quantities, we explore the consequences of a momentum-independent interaction, regularized in a symmetry-preserving manner. The contact interaction, while capable of describing pion static properties, produces a form factor whose evolution for Q{sup 2}>0.17 GeV{sup 2} disagrees markedly with experiment and whose asymptotic power-law behavior conflicts strongly with perturbative QCD.

  6. Pion form factor from a contact interaction.

    SciTech Connect

    Gutierrez-Guerrero, L. X.; Bashir, A.; Cloet, I. C.; Roberts, C. D.

    2010-01-01

    In a Poincare-covariant vector-boson-exchange theory, the pion possesses components of pseudovector origin, which materially influence its observable properties. For a range of such quantities, we explore the consequences of a momentum-independent interaction, regularized in a symmetry-preserving manner. The contact interaction, while capable of describing pion static properties, produces a form factor whose evolution for Q{sup 2} > 0.17 GeV{sup 2} disagrees markedly with experiment and whose asymptotic power-law behavior conflicts strongly with perturbative QCD.

  7. Ink-Jet Printer Forms Solar-Cell Contacts

    NASA Technical Reports Server (NTRS)

    Alexander, Paul, Jr.; Vest, R. W.; Binford, Don A.; Tweedell, Eric P.

    1988-01-01

    Contacts formed in controllable patterns with metal-based inks. System forms upper metal contact patterns on silicon photovoltaic cells. Uses metallo-organic ink, decomposes when heated, leaving behind metallic, electrically conductive residue in printed area.

  8. Method of forming contacts for a back-contact solar cell

    DOEpatents

    Manning, Jane

    2013-07-23

    Methods of forming contacts for back-contact solar cells are described. In one embodiment, a method includes forming a thin dielectric layer on a substrate, forming a polysilicon layer on the thin dielectric layer, forming and patterning a solid-state p-type dopant source on the polysilicon layer, forming an n-type dopant source layer over exposed regions of the polysilicon layer and over a plurality of regions of the solid-state p-type dopant source, and heating the substrate to provide a plurality of n-type doped polysilicon regions among a plurality of p-type doped polysilicon regions.

  9. Method of forming contacts for a back-contact solar cell

    SciTech Connect

    Manning, Jane

    2015-10-20

    Methods of forming contacts for solar cells are described. In one embodiment, a method includes forming a silicon layer above a substrate, forming and patterning a solid-state p-type dopant source on the silicon layer, forming an n-type dopant source layer over exposed regions of the silicon layer and over a plurality of regions of the solid-state p-type dopant source, and heating the substrate to provide a plurality of n-type doped silicon regions among a plurality of p-type doped silicon regions.

  10. Method of forming contacts for a back-contact solar cell

    SciTech Connect

    Manning, Jane

    2014-07-15

    Methods of forming contacts for solar cells are described. In one embodiment, a method includes forming a silicon layer above a substrate, forming and patterning a solid-state p-type dopant source on the silicon layer, forming an n-type dopant source layer over exposed regions of the silicon layer and over a plurality of regions of the solid-state p-type dopant source, and heating the substrate to provide a plurality of n-type doped silicon regions among a plurality of p-type doped silicon regions.

  11. Contact-spring forming machine for flat conductor cable receptacles

    NASA Technical Reports Server (NTRS)

    Angele, W.; Martineck, H. G.

    1968-01-01

    Machine tool produces beryllium-copper contact springs for FCC /flat conductor cable/ feed-through receptacles. The springs are heat-treated and plated to impart the required electrical contact properties.

  12. Process and structures for fabrication of solar cells with laser ablation steps to form contact holes

    DOEpatents

    Harley, Gabriel; Smith, David D; Dennis, Tim; Waldhauer, Ann; Kim, Taeseok; Cousins, Peter John

    2013-11-19

    Contact holes of solar cells are formed by laser ablation to accomodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thickness.

  13. Phonological Convergence in Dialect Contact: Evidence from Citation Forms.

    ERIC Educational Resources Information Center

    Kerswill, Paul

    1995-01-01

    Using data from three experimental studies on British English, this study addresses whether, in dialect contact, there is a difference in the degree of convergence at different phonological levels. Data suggest that, in a contact situation, surface differences will be eradicated at the expense of phonologically complex differences. (29 references)…

  14. 78 FR 58608 - Proposed Collection; Comment Request for the EFTPS Primary Contact Information Change Form

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-24

    ... Internal Revenue Service Proposed Collection; Comment Request for the EFTPS Primary Contact Information... the EFTPS Primary Contact Information Change Form. DATES: Written comments should be received on or.... FOR FURTHER INFORMATION CONTACT: Requests for additional information or copies of the form...

  15. 75 FR 61245 - Proposed Collection; Comment Request for the EFTPS Primary Contact Information Change Form

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ... Internal Revenue Service Proposed Collection; Comment Request for the EFTPS Primary Contact Information... the EFTPS Primary Contact Information Change Form. DATES: Written comments should be received on or.... FOR FURTHER INFORMATION CONTACT: Requests for additional information or copies of the form...

  16. Helicobacter pylori TlyA Forms Amyloid-like Aggregates with Potent Cytotoxic Activity.

    PubMed

    Lata, Kusum; Chattopadhyay, Kausik

    2015-06-16

    Helicobacter pylori is a potent human gastric pathogen. It is known to be associated with several gastroenteric disorders, including gastritis, peptic ulcer, and gastric cancer. The H. pylori genome encodes a gene product TlyA that has been shown to display potent membrane damaging properties and cytotoxic activity. On the basis of such properties, TlyA is considered as a potential virulence factor of H. pylori. In this study, we show that the H. pylori TlyA protein has a strong propensity to convert into the amyloid-like aggregated assemblies, upon exposure to elevated temperatures. Even at the physiological temperature of 37 C, TlyA shows a strong amyloidogenic property. TlyA aggregates that are generated upon exposure at temperatures of ?37 C show prominent binding to dyes like thioflavin T and Nile Red. Transmission electron microscopy also demonstrates the presence of typical amyloid-like fibrils in the TlyA aggregates generated at 37 C. Conversion of TlyA into the amyloid-like aggregates is found to be associated with major alterations in the secondary and tertiary structural organization of the protein. Finally, our study shows that the preformed amyloid-like aggregates of TlyA are capable of exhibiting potent cytotoxic activities against human gastric adenocarcinoma cells. Altogether, such a propensity of H. pylori TlyA to convert into the amyloid-like aggregated assemblies with cytotoxic activity suggests potential implications for the virulence functionality of the protein. PMID:26015064

  17. 41 CFR 102-194.45 - Who should I contact about Standard and Optional forms?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Who should I contact about Standard and Optional forms? 102-194.45 Section 102-194.45 Public Contracts and Property... about Standard and Optional forms? For Standard and Optional forms, you should contact the: Standard...

  18. Back contacted and small form factor GAAS solar cell.

    SciTech Connect

    Clews, Peggy Jane; Wanlass, Mark W.; Sanchez, Carlos A.; Pluym, Tammy; Cruz-Campa, Jose Luis; Okandan, Murat; Gupta, Vipin P.; Nielson, Gregory N.; Resnick, Paul James

    2010-06-01

    We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

  19. Chronic, irritant contact dermatitis: Mechanisms, variables, and differentiation from other forms of contact dermatitis

    SciTech Connect

    Dahl, M.V. )

    1988-01-01

    Irritant dermatitis is an eczematous reaction to toxic chemicals contacting the skin. The mechanisms by which various chemicals elicit dermatitis are multiple. Strong irritants quickly elicit signs and symptoms of dermatitis, but weak irritants may not. Chronic cumulative exposure to weak irritants can elicit dermatitis which may mimic allergic contact dermatitis and mislead the physician and patient with respect to cause and preventative strategy. The skins of different people vary in susceptibilities to irritation. Susceptibility is also influenced by chemical properties, vehicles, concentrations, amounts applied to the skin surface, surface area, regional variations, length of exposure, method of exposure, age, sex, race, genetic background, environmental factors, hardening, concomitant disease, and the excited skin syndrome as well as treatment. Patch testing can help distinguish between allergens and irritants, but pitfalls may mislead.35 references.

  20. Thermal Contact Resistance Estimation: Influence of the Pressure Contact and the Coating Layer during a Hot Forming Process

    NASA Astrophysics Data System (ADS)

    Abdulhay, B.; Bourouga, B.; Dessain, C.

    2011-05-01

    The application of hot stamping in the automotive industry has experienced a fast growth due to the need for higher passive safety and weight reduction. Today, it is absolutely necessary to have reliable and accurate simulation predictions in order to assess the forming feasibility of a part as early as possible during the car design phase. In this paper, an original experimental procedure developed to estimate the thermal conductance at the Part-Tools interfaces during a hot stamping process, is presented. The tools set (punch and die) have been designed to form samples with an omega shape. Two types of material have been stamped: the Usibor 1500P® and the 22MnB5 galvanized steel. The object is to describe correctly the thermal boundary conditions at the Part-Tools interfaces; the adopted procedure consists in estimating accurately the thermal contact resistance TCR at different contact points for different contact pressure values.

  1. Gear sound levels with various tooth contact ratios and forms

    NASA Technical Reports Server (NTRS)

    Lenski, Joseph W., Jr.; Spencer, Robert H.; Drago, Raymond J.; Valco, Mark J.; Oswald, Fred B.

    1993-01-01

    The real noise reduction benefits which may be obtained through the use of one gear tooth form as compared to another is an important design parameter for any geared system, especially for helicopters in which both weight and reliability are very important factors. The design and testing of nine sets of gears which are as identical as possible except for their basic tooth geometry are described. Noise measurements were made at various combinations of load and speed for each gear set so that direct comparisons could be made. The resultant data was analyzed so that valid conclusions could be drawn and interpreted for design use.

  2. Identification of potent odorants formed during the preparation of extruded potato snacks.

    PubMed

    Majcher, Ma?gorzata A; Jele?, Henryk H

    2005-08-10

    Extrusion cooking processing followed by air-drying has been applied to obtain low-fat potato snacks. Optimal parameters were developed for a dough recipe. Dough contained apart from potato granules 7% of canola oil, 1% of salt, 1% of baking powder, 5% of maltodextrin, and 15% of wheat flour. After the extrusion process, snacks were dried at 85 degrees C for 15 min followed by 130 degrees C for 45 min. The potent odorants of extruded potato snacks were identified using aroma extract dilution analysis and gas chromatography-olfactometry. Among the characteristic compounds, methional with boiled potato flavor, benzenemethanethiol with pepper-seed flavor, 2-acetyl-1-pyrroline with popcorn flavor, benzacetaldehyde with strong flowery flavor, butanal with rancid flavor, and 2-acetylpyrazine with roasty flavor were considered to be the main contributors to the aroma of extruded potato snacks. Several compounds were concluded to be developed during extrusion cooking, such as ethanol, 3-methylbutanal, (Z)-1,5-octadien-3-one with geranium flavor, and unknown ones with the flavor of boiled potato, cumin, candy, or parsley root. Compounds such as methanethiol, 2,3-pentanedione, limonene, 2-acetylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 2-methyl-3,5-diethylpyrazine, 5-methyl-2,3-diethylpyrazine, and (E)-beta-damascenone were probably developed during air-drying of the potato extrudate. PMID:16076130

  3. 78 FR 23898 - Notice of Request for a New Information Collection (Accredited Laboratory Contact Update Form)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-23

    ... Laboratory Contact Update Form) AGENCY: Food Safety and Inspection Service, USDA. ACTION: Notice and request... intention to request a new information collection regarding the compilation of updated contact information..., DC 20250-3700 between 8:00 a.m. and 4:30 p.m., Monday through Friday. FOR FURTHER INFORMATION...

  4. Observations on the Influence of Tool-Sheet Contact Conditions on an Incremental Forming Process

    NASA Astrophysics Data System (ADS)

    Durante, M.; Formisano, A.; Langella, A.

    2011-08-01

    The influence of tool-sheet contact conditions on features such as surface roughness, forming force, and formability was evaluated for components produced by incremental forming, a highly flexible innovative sheet metal-forming process. Experimental tests were carried out on sheets of AA7075T0 to create two types of component: pyramid frusta (for the evaluation of roughness and force) and cone frusta (for the evaluation of formability). Four different types of tool-sheet contact were analyzed, using two types of tool. From the experimental tests, the influence on the surface finishing and on the trend of the forming forces depending on contact type was revealed. Contact types do not, however, influence sheet formability.

  5. Method of forming emitters for a back-contact solar cell

    DOEpatents

    Li, Bo; Cousins, Peter J; Smith, David D

    2014-12-16

    Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

  6. Method or forming emitters for a back-contact solar cell

    DOEpatents

    Li, Bo; Cousins, Peter J.; Smith, David D.

    2014-08-12

    Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

  7. Method of forming emitters for a back-contact solar cell

    DOEpatents

    Li, Bo; Cousins, Peter J.; Smith, David D.

    2015-09-29

    Methods of forming emitters for back-contact solar cells are described. In one embodiment, a method includes forming a first solid-state dopant source above a substrate. The first solid-state dopant source includes a plurality of regions separated by gaps. Regions of a second solid-state dopant source are formed above the substrate by printing.

  8. Tunnel oxide passivated contacts formed by ion implantation for applications in silicon solar cells

    NASA Astrophysics Data System (ADS)

    Reichel, Christian; Feldmann, Frank; Müller, Ralph; Reedy, Robert C.; Lee, Benjamin G.; Young, David L.; Stradins, Paul; Hermle, Martin; Glunz, Stefan W.

    2015-11-01

    Passivated contacts (poly-Si/SiOx/c-Si) doped by shallow ion implantation are an appealing technology for high efficiency silicon solar cells, especially for interdigitated back contact (IBC) solar cells where a masked ion implantation facilitates their fabrication. This paper presents a study on tunnel oxide passivated contacts formed by low-energy ion implantation into amorphous silicon (a-Si) layers and examines the influence of the ion species (P, B, or BF2), the ion implantation dose (5 × 1014 cm-2 to 1 × 1016 cm-2), and the subsequent high-temperature anneal (800 °C or 900 °C) on the passivation quality and junction characteristics using double-sided contacted silicon solar cells. Excellent passivation quality is achieved for n-type passivated contacts by P implantations into either intrinsic (undoped) or in-situ B-doped a-Si layers with implied open-circuit voltages (iVoc) of 725 and 720 mV, respectively. For p-type passivated contacts, BF2 implantations into intrinsic a-Si yield well passivated contacts and allow for iVoc of 690 mV, whereas implanted B gives poor passivation with iVoc of only 640 mV. While solar cells featuring in-situ B-doped selective hole contacts and selective electron contacts with P implanted into intrinsic a-Si layers achieved Voc of 690 mV and fill factor (FF) of 79.1%, selective hole contacts realized by BF2 implantation into intrinsic a-Si suffer from drastically reduced FF which is caused by a non-Ohmic Schottky contact. Finally, implanting P into in-situ B-doped a-Si layers for the purpose of overcompensation (counterdoping) allowed for solar cells with Voc of 680 mV and FF of 80.4%, providing a simplified and promising fabrication process for IBC solar cells featuring passivated contacts.

  9. Disruption of Contact Lens–Associated Pseudomonas aeruginosa Biofilms Formed in the Presence of Neutrophils

    PubMed Central

    Parks, Quinn M.; Young, Robert L.; Kret, Jennifer; Poch, Katie R.; Malcolm, Kenneth C.; Nichols, David P.; Nichols, Michelle; Zhu, Meifang; Cavanagh, H. Dwight; Nick, Jerry A.

    2011-01-01

    Purpose. To evaluate the capacity of neutrophils to enhance biofilm formation on contact lenses by an infectious Pseudomonas aeruginosa (PA) corneal isolate. Agents that target F-actin and DNA were tested as a therapeutic strategy for disrupting biofilms formed in the setting of neutrophils in vitro and for limiting the infectious bioburden in vivo. Methods. Biofilm formation by infectious PA strain 6294 was assessed in the presence of neutrophils on a static biofilm plate and on unworn etafilcon A soft contact lenses. A d-isomer of poly(aspartic acid) was used alone and with DNase to reduce biofilm formation on test contact lenses. The gentamicin survival assay was used to determine the effectiveness of the test compound in reducing subsequent intracellular bacterial load in the corneal epithelium in a contact lens infection model in the rabbit. Results. In a static reactor and on hydrogel lenses, PA biofilm density was enhanced 30-fold at 24 hours in the presence of neutrophils (P < 0.0001). The combination of DNase and anionic poly(aspartic acid) reduced the PA biofilms formed in the presence of activated neutrophils by 79.2% on hydrogel contact lenses (P < 0.001). An identical treatment resulted in a 41% reduction in internalized PA in the rabbit corneal epithelium after 24 hours (P = 0.03). Conclusions. These results demonstrate that PA can exploit the presence of neutrophils to form biofilm on contact lenses within a short time. Incorporation of F-actin and DNA represent a mechanism for neutrophil-induced biofilm enhancement and are targets for available agents to disrupt pathogenic biofilms formed on contact lenses and as a treatment for established corneal infections. PMID:21245396

  10. The G-quadruplex-forming aptamer AS1411 potently inhibits HIV-1 attachment to the host cell

    PubMed Central

    Perrone, Rosalba; Butovskaya, Elena; Lago, Sara; Garzino-Demo, Alfredo; Pannecouque, Christophe; Palù, Giorgio; Richter, Sara N.

    2016-01-01

    AS1411 is a G-rich aptamer that forms a stable G-quadruplex structure and displays antineoplastic properties both in vitro and in vivo. This oligonucleotide has undergone phase 2 clinical trials. The major molecular target of AS1411 is nucleolin (NCL), a multifunctional nucleolar protein also present in the cell membrane where it selectively mediates the binding and uptake of AS1411. Cell-surface NCL has been recognised as a low-affinity co-receptor for human immunodeficiency virus type 1 (HIV-1) anchorage on target cells. Here we assessed the anti-HIV-1 properties and underlying mechanism of action of AS1411. The antiviral activity of AS1411 was determined towards different HIV-1 strains, host cells and at various times post-infection. Acutely, persistently and latently infected cells were tested, including HIV-1-infected peripheral blood mononuclear cells from a healthy donor. Mechanistic studies to exclude modes of action other than virus binding via NCL were performed. AS1411 efficiently inhibited HIV-1 attachment/entry into the host cell. The aptamer displayed antiviral activity in the absence of cytotoxicity at the tested doses, therefore displaying a wide therapeutic window and favourable selectivity indexes. These findings, besides validating cell-surface-expressed NCL as an antiviral target, open the way for the possible use of AS1411 as a new potent and promisingly safe anti-HIV-1 agent. PMID:27032748

  11. The G-quadruplex-forming aptamer AS1411 potently inhibits HIV-1 attachment to the host cell.

    PubMed

    Perrone, Rosalba; Butovskaya, Elena; Lago, Sara; Garzino-Demo, Alfredo; Pannecouque, Christophe; Palù, Giorgio; Richter, Sara N

    2016-04-01

    AS1411 is a G-rich aptamer that forms a stable G-quadruplex structure and displays antineoplastic properties both in vitro and in vivo. This oligonucleotide has undergone phase 2 clinical trials. The major molecular target of AS1411 is nucleolin (NCL), a multifunctional nucleolar protein also present in the cell membrane where it selectively mediates the binding and uptake of AS1411. Cell-surface NCL has been recognised as a low-affinity co-receptor for human immunodeficiency virus type 1 (HIV-1) anchorage on target cells. Here we assessed the anti-HIV-1 properties and underlying mechanism of action of AS1411. The antiviral activity of AS1411 was determined towards different HIV-1 strains, host cells and at various times post-infection. Acutely, persistently and latently infected cells were tested, including HIV-1-infected peripheral blood mononuclear cells from a healthy donor. Mechanistic studies to exclude modes of action other than virus binding via NCL were performed. AS1411 efficiently inhibited HIV-1 attachment/entry into the host cell. The aptamer displayed antiviral activity in the absence of cytotoxicity at the tested doses, therefore displaying a wide therapeutic window and favourable selectivity indexes. These findings, besides validating cell-surface-expressed NCL as an antiviral target, open the way for the possible use of AS1411 as a new potent and promisingly safe anti-HIV-1 agent. PMID:27032748

  12. Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials

    DOEpatents

    Hogan, S.J.

    1983-03-13

    Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components a n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffuse layer and the substrate layer wherein the n-type layer comprises a substantially low doping carrier concentration.

  13. Front contact solar cell with formed electrically conducting layers on the front side and backside

    DOEpatents

    Cousins, Peter John

    2012-06-26

    A bipolar solar cell includes a backside junction formed by a silicon substrate and a first doped layer of a first dopant type on the backside of the solar cell. A second doped layer of a second dopant type makes an electrical connection to the substrate from the front side of the solar cell. A first metal contact of a first electrical polarity electrically connects to the first doped layer on the backside of the solar cell, and a second metal contact of a second electrical polarity electrically connects to the second doped layer on the front side of the solar cell. An external electrical circuit may be electrically connected to the first and second metal contacts to be powered by the solar cell.

  14. Rice endosperm produces an underglycosylated and potent form of the HIV-neutralizing monoclonal antibody 2G12.

    PubMed

    Vamvaka, Evangelia; Twyman, Richard M; Murad, Andre Melro; Melnik, Stanislav; Teh, Audrey Yi-Hui; Arcalis, Elsa; Altmann, Friedrich; Stoger, Eva; Rech, Elibio; Ma, Julian K C; Christou, Paul; Capell, Teresa

    2016-01-01

    Protein microbicides against HIV can help to prevent infection but they are required in large, repetitive doses. This makes current fermenter-based production systems prohibitively expensive. Plants are advantageous as production platforms because they offer a safe, economical and scalable alternative, and cereals such as rice are particularly attractive because they could allow pharmaceutical proteins to be produced economically and on a large scale in developing countries. Pharmaceutical proteins can also be stored as unprocessed seed, circumventing the need for a cold chain. Here, we report the development of transgenic rice plants expressing the HIV-neutralizing antibody 2G12 in the endosperm. Surprisingly for an antibody expressed in plants, the heavy chain was predominantly aglycosylated. Nevertheless, the heavy and light chains assembled into functional antibodies with more potent HIV-neutralizing activity than other plant-derived forms of 2G12 bearing typical high-mannose or plant complex-type glycans. Immunolocalization experiments showed that the assembled antibody accumulated predominantly in protein storage vacuoles but also induced the formation of novel, spherical storage compartments surrounded by ribosomes indicating that they originated from the endoplasmic reticulum. The comparison of wild-type and transgenic plants at the transcriptomic and proteomic levels indicated that endogenous genes related to starch biosynthesis were down-regulated in the endosperm of the transgenic plants, whereas genes encoding prolamin and glutaredoxin-C8 were up-regulated. Our data provide insight into factors that affect the functional efficacy of neutralizing antibodies in plants and the impact of recombinant proteins on endogenous gene expression. PMID:25845722

  15. Effects of varying machine stiffness and contact area in UltraForm Finishing

    NASA Astrophysics Data System (ADS)

    Briggs, Dennis E.; Echaves, Samantha; Pidgeon, Brendan; Travis, Nathan; Ellis, Jonathan D.

    2013-09-01

    UltraForm Finishing (UFF) is a deterministic, subaperture, computer numerically controlled, grinding and polishing platform designed by OptiPro Systems. UFF is used to grind and polish a variety optics from simple spherical to fully freeform, and numerous materials from glasses to optical ceramics. The UFF system consists of an abrasive belt around a compliant wheel that rotates and contacts the part to remove material. This work aims to measure the stiffness variations in the system and how it can affect material removal rates. The stiffness of the entire system is evaluated using a triaxial load cell to measure forces and a capacitance sensor to measure deviations in height. Because the wheel is conformal and elastic, the shapes of contact areas are also of interest. For the scope of this work, the shape of the contact area is estimated via removal spot. The measured forces and removal spot area are directly related to material removal rate through Preston's equation. Using our current testing apparatus, we will demonstrate stiffness measurements and contact areas for a single UFF belt during different states of its lifecycle and assess the material removal function from spot diagrams as a function of wear. This investigation will ultimately allow us to make better estimates of Preston's coefficient and develop spot-morphing models in an effort to more accurately predict instantaneous material removal functions throughout the lifetime of a belt.

  16. Form, figure, and thickness measurement of freeform and conformal optics with non-contact sensors

    NASA Astrophysics Data System (ADS)

    DeFisher, Scott; Fess, Edward; Matthews, Greg

    2014-05-01

    Advancements in optical manufacturing technology allow optical designers to implement freeform and conformal shapes in their systems. Metrology of the shapes has traditionally been difficult, especially at the sub-micron level. Contact measuring systems typically lack the accuracy required for optical qualification and can damage the surface. Interferometric systems are unable to handle high spherical departures and may require complicated lateral calibration to generate feedback for deterministic grinding and polishing. OptiPro has developed UltraSurf, a noncontact coordinate measuring machine to determine the form, figure, and thickness of freeform and conformal optics. We integrated several non-contact sensors that acquire surface information through different optical principles. Each probe has strength and weaknesses relative to an optic's material properties, surface finish, and figure error. The measuring probe is scanned over the optical surface while maintaining perpendicularity and a constant focal offset. Measurements of freeform and conformal shapes will be presented. The scanning method of UltraSurf and the non-contact probes will also be shown. The form, figure, and thickness data will highlight the capabilities of UltraSurf to measure freeform surfaces. Comparisons between accuracy and measureable surface departure will be made with current metrology systems such as coordinate measuring machines, interferometers, and profilometers. Additionally, methods for defining a freeform or conformal surface for metrology analysis and manufacturing will be discussed.

  17. Detection of organochlorine compounds formed during the contact of sodium hypochlorite with dentin and dental pulp.

    PubMed

    Varise, Tiago Gilioli; Estrela, Carlos; Guedes, Débora Fernandes Costa; Sousa-Neto, Manoel Damião; Pécora, Jesus Djalma

    2014-01-01

    This study used gas chromatography-mass spectrometry (GC-MS) to detect the products formed during the contact of sodium hypochlorite (NaOCl) with bovine pulp and dentin. For analysis of the products formed in the volatile phase, 11 mg of bovine pulp tissue were placed in contact with 0.5%, 2.5% and 5.25% NaOCl until complete tissue dissolution occurred. The solid phase microextraction (SPME) fiber was exposed inside the container through the cover membrane and immediately injected into the GC-MS system. 30 mg of the of dentin were kept in contact with NaOCl, and then the SPME fiber was exposed inside the container through the cover membrane for adsorption of the products and injected into the GC-MS system. The same protocol was used for the aqueous phase. For analysis of the volatile compounds, the final solution was extracted using pure ethyl ether. The suspended particulate phase of the mixture was aspirated, and ether was separated from the aqueous phase of the solution. The ether containing the products that resulted from the chemical interaction of dentin and pulp with the NaOCl was filtered and then injected into the GC-MS system for analysis of the aqueous phase. The aqueous and volatile phases of both dentin and pulp showed the formation of chloroform, hexachloroethane, dichloromethylbenzene and benzaldehyde. In conclusion, organochlorine compounds are generated during the contact of dentin and pulp with NaOCl at concentrations of 0.5%, 2.5% and 5.25%. PMID:25140714

  18. Rhodopsin forms a dimer with cytoplasmic helix 8 contacts in native membranes

    PubMed Central

    Knepp, Adam M.; Periole, Xavier; Marrink, Siewert-Jan; Sakmar, Thomas P.; Huber, Thomas

    2012-01-01

    G protein-coupled receptors (GPCRs) form dimers and higher-order oligomers in membranes, but the precise mode of receptor-receptor interaction remains unknown. To probe the intradimeric proximity of helix 8 (H8), we carried out chemical crosslinking of endogenous cysteines in rhodopsin in disk membranes. We identified a Cys316–Cys316 crosslink using partial proteolysis and liquid chromatography-mass spectrometry (LC-MS). These results show that a symmetric dimer interface mediated by H1 and H8 contacts is present in native membranes. PMID:22352709

  19. Non-contact automatic measurement of free-form surface profiles on CNC machines

    NASA Astrophysics Data System (ADS)

    Fan, Kuang-Chao; Wen, Kuang-Pu

    1993-09-01

    This paper describes the work to develop a non-contact type automatic measurement system for any free-form surfaces on a CNC machine tool or a coordinate measuring machine (CMM) and its CAD/CAM integration. A laser probe made by Keyence Co. model LC-2220 was integrated into the CNC machine as the non-contact sensor. A measurement software has been developed for automatic surface tracing of any free-form profile. Data transfer to any commercially available CAD/CAM system for reverse engineering is also available via proper DXF file. Extensive calibration work has been carried out on the systematic accuracy of the laser probe with respect to the color material surface slope and edge detection of the workpiece by the use of a HP5528 laser interferometer system. Having employed the surface painting technique the shape error of the copied object relative to its master piece was found within 30 micrometers which is deemed adequate enough to the mold industry.

  20. Chromium is proposed as an ideal metal to form contacts with monolayer MoS2 and WS2

    NASA Astrophysics Data System (ADS)

    Luo, B.; Liu, J.; Zhu, S. C.; Yi, L.

    2015-10-01

    In this paper, fifteen kinds of metal contacts to monolayer MoS2 and WS2 are investigated by first principles calculations. In a variety of metal contacts, the sixth subgroup metals (including Cr, Mo, W) show collective advantages in forming contacts with MoS2 or WS2. They have more favorable interface bonding, higher densities of states at the Fermi level, and lower potential barriers. Molybdenum (Mo) is one of the elements that form molybdenum disulphide (MoS2), and has been proved to form high quality contacts with MoS2. Similarly, tungsten (W) is one of the elements that form tungsten tellurium (WTe2), and is suggested to form favorable contacts with WTe2. The third metal in the sixth subgroup, chromium (Cr), is found here to be a superior metal compared with molybdenum and tungsten to form favorable contacts with molybdenum disulphide and tungsten disulphide. In all sixth subgroup metal contacts, Cr/MoS2 and Cr/WS2 show the best electronic transport properties and chromium has a lower melting point than molybdenum and tungsten, which lead to easier to process devices with transition-metal dichalcogenides.

  1. Special dendritic and axonal endings formed by the cerebrospinal fluid contacting neurons of the spinal cord.

    PubMed

    Vigh, B; Vigh-Teichmann, I; Aros, B

    1977-10-14

    The cerebrospinal fluid (CSF) contacting neurons have a dendritic process which protrudes into the central canal, and is provided with one long kinocilium and many shorter stereocilia (about 80 in the turtle) as revealed by scanning electron mecroscopy. The shape, number and arrangement of the cilia are similar to those of known receptor endings. The silver impregnated axons of these cells converge to a paired centrosuperficial tract forming terminal enlargements at the ventrolateral surface of the spinal cord. Lying among glial endfeet these terminals are ultrastructurally similar to those present in known neurosecretory areas. The nerve endings are attached to the basal lamina, and they comprise many synaptic vesicles (200 to 400 A in diameter), as well as granular vesicles of different sizes (diameter 600 to 1800 A). The axons may lie within finger-like protrusions on the surface of the spinal cord, or they may terminate around vesseles. Morphological evidence suggests that these nerve terminals and the corresponding CSF contacting perikarya represent a spinal neurosecretory system possibly influenced by information taken up by its special dendrites protruding into the inner CSF space. PMID:922853

  2. Interrogating alkyl and arylalkylpolyamino (bis)urea and (bis)thiourea isosteres as potent antimalarial chemotypes against multiple lifecycle forms of Plasmodium falciparum parasites.

    PubMed

    Verlinden, Bianca K; de Beer, Marna; Pachaiyappan, Boobalan; Besaans, Ethan; Andayi, Warren A; Reader, Janette; Niemand, Jandeli; van Biljon, Riette; Guy, Kiplin; Egan, Timothy; Woster, Patrick M; Birkholtz, Lyn-Marie

    2015-08-15

    A new series of potent potent aryl/alkylated (bis)urea- and (bis)thiourea polyamine analogues were synthesized and evaluated in vitro for their antiplasmodial activity. Altering the carbon backbone and terminal substituents increased the potency of analogues in the compound library 3-fold, with the most active compounds, 15 and 16, showing half-maximal inhibitory concentrations (IC50 values) of 28 and 30 nM, respectively, against various Plasmodium falciparum parasite strains without any cross-resistance. In vitro evaluation of the cytotoxicity of these analogues revealed marked selectivity towards targeting malaria parasites compared to mammalian HepG2 cells (>5000-fold lower IC50 against the parasite). Preliminary biological evaluation of the polyamine analogue antiplasmodial phenotype revealed that (bis)urea compounds target parasite asexual proliferation, whereas (bis)thiourea compounds of the same series have the unique ability to block transmissible gametocyte forms of the parasite, indicating pluripharmacology against proliferative and non-proliferative forms of the parasite. In this manuscript, we describe these results and postulate a refined structure-activity relationship (SAR) model for antiplasmodial polyamine analogues. The terminally aryl/alkylated (bis)urea- and (bis)thiourea-polyamine analogues featuring a 3-5-3 or 3-6-3 carbon backbone represent a structurally novel and distinct class of potential antiplasmodials with activities in the low nanomolar range, and high selectivity against various lifecycle forms of P. falciparum parasites. PMID:25684422

  3. Interrogating alkyl and arylalkylpolyamino (bis)urea and (bis)thiourea isosteres as potent antimalarial chemotypes against multiple lifecycle forms of Plasmodium falciparum parasites

    PubMed Central

    Verlinden, Bianca K.; de Beer, Marna; Pachaiyappan, Boobalan; Besaans, Ethan; Andayi, Warren A.; Reader, Janette; Niemand, Jandeli; van Biljon, Riette; Guy, Kiplin; Egan, Timothy; Woster, Patrick M.; Birkholtz, Lyn-Marie

    2015-01-01

    A new series of potent potent aryl/alkylated (bis)urea- and (bis)thiourea polyamine analogues were synthesized and evaluated in vitro for their antiplasmodial activity. Altering the carbon backbone and terminal substituents increased the potency of analogues in the compound library 3-fold, with the most active compounds, 15 and 16, showing half-maximal inhibitory concentrations (IC50 values) of 28 and 30 nM, respectively, against various Plasmodium falciparum parasite strains without any cross-resistance. In vitro evaluation of the cytotoxicity of these analogues revealed marked selectivity towards targeting malaria parasites compared to mammalian HepG2 cells (>5000-fold lower IC50 against the parasite). Preliminary biological evaluation of the polyamine analogue antiplasmodial phenotype revealed that (bis)urea compounds target parasite asexual proliferation, whereas (bis)thiourea compounds of the same series have the unique ability to block transmissible gametocyte forms of the parasite, indicating pluripharmacology against proliferative and non-proliferative forms of the parasite. In this manuscript, we describe these results and postulate a refined structure-activity relationship (SAR) model for antiplasmodial polyamine analogues. The terminally aryl/alkylated (bis)urea- and (bis)thiourea-polyamine analogues featuring a 3-5-3 or 3-6-3 carbon backbone represent a structurally novel and distinct class of potential antiplasmodials with activities in the low nanomolar range, and high selectivity against various lifecycle forms of P. falciparum parasites. PMID:25684422

  4. Specific Contact Resistance Measurement of Screen-Printed Ag Metal Contacts Formed on Heavily Doped Emitter Region in Multicrystalline Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Vinod, P. Narayanan

    2013-10-01

    Multicrystalline silicon (mc-Si) wafers are widely used to develop low-cost high-efficiency screen-printed solar cells. In this study, the electrical properties of screen-printed Ag metal contacts formed on heavily doped emitter region in mc-Si solar cells have been investigated. Sintering of the screen-printed metal contacts was performed by a co-firing step at 725°C in air ambient followed by low-temperature annealing at 450°C for 15 min. Measurement of the specific contact resistance ( ρ c) of the Ag contacts was performed by the three-point probe method, showing a best value of ρ c = 1.02 × 10-4 Ω cm2 obtained for the Ag contacts. This value is considered as a good figure of merit for screen-printed Ag electrodes formed on a doped mc-Si surface. The plot of ρ c versus the inverse of the square root of the surface doping level ( N {s/-½}) follows a linear relationship for impurity doping levels N s ≥ 1019 atoms/cm3. The power losses due to current traveling through various resistive components of finished solar cells were calculated by using standard expressions. Cross-sectional scanning electron microscopy (SEM) views of the Ag metal and doped mc-Si region show that the Ag metal is firmly coalesced with the doped mc-Si surface upon sintering at an optimum firing temperature of 725°C.

  5. A nanorod polymer micro-array formed by micro-contact printing

    NASA Astrophysics Data System (ADS)

    Roche, Philip J. R.; Wang, Songzhe; Cheung, Maurice C. K.; Chodavarapu, Vamsy P.; Kirk, Andrew G.

    2012-03-01

    In previous work, we demonstrate a simple approach to creating a plasmonic polymer. Reflecting upon the need for greater spot density while still maintaining the objective of low cost analysis, the next generation of device is described where density up to 24000 sensing spots is achievable. A localized surface plasmon micro-array is described formed by single or multiple deposition of a nanorod plasmonic polymer by micro-contact printing. The structure of the polymer can be made micro-porous and thickness can be controlled by a cyclical deposition and rapid heat cure protocol. The consistency of feature deposition is assessed. The resulting micro-structure provides a large surface area for immobilization of biomolecules for assay development. Dark-field analysis of the polymer demonstrates complex microstructure and intense Mie Scattering as expected from gold nanorods. Using fluorescence confocal analysis images of the polymer demonstrates two independent photo-luminescent emission spectra. The two independent emission spectra are linked to the positions of the localized surface plasmons of the nanorods, using a pump source of 543nm excites the transverse plasmon (peak at 550nm)and it's commensurate emission, but doesn't excite the longer emission around 700nm that is linked to the longitudinal Plasmon around 737nm. The different emissions are demonstrated in the illumination of different portions of the polymer matrix under each pump source excitation. The potential for multiple spectroscopic biosensor analysis is discussed.

  6. Method for forming low-resistance ohmic contacts on semiconducting oxides

    DOEpatents

    Narayan, J.

    1979-10-01

    The invention provides a new method for the formation of high-quality ohmic contacts on wide-band-gap semiconducting oxides. As exemplified by the formation of an ohmic contact on n-type BaTiO/sub 3/ containing a p-n junction, the invention entails depositing a film of a metallic electroding material on the BaTiO/sub 3/ surface and irradiating the film with a Q-switched laser pulse effecting complete melting of the film and localized melting of the surface layer of oxide immediately underlying the film. The resulting solidified metallic contact is ohmic, has unusually low contact resistance, and is thermally stable, even at elevated temmperatures. The contact does not require cleaning before attachment of any suitable electrical lead. This method is safe, rapid, reproducible, and relatively inexpensive.

  7. Laser method for forming low-resistance ohmic contacts on semiconducting oxides

    DOEpatents

    Narayan, Jagdish

    1981-01-01

    This invention is a new method for the formation of high-quality ohmic contacts on wide-band-gap semiconducting oxides. As exemplified by the formation of an ohmic contact on n-type BaTiO.sub.3 containing a p-n junction, the invention entails depositing a film of a metallic electroding material on the BaTiO.sub.3 surface and irradiating the film with a Q-switched laser pulse effecting complete melting of the film and localized melting of the surface layer of oxide immediately underlying the film. The resulting solidified metallic contact is ohmic, has unusually low contact resistance, and is thermally stable, even at elevated temperatures. The contact does not require cleaning before attachment of any suitable electrical lead. This method is safe, rapid, reproducible, and relatively inexpensive.

  8. Pt/Ti/n-InP nonalloyed ohmic contacts formed by rapid thermal processing

    NASA Astrophysics Data System (ADS)

    Katz, A.; Weir, B. E.; Chu, S. N. G.; Thomas, P. M.; Soler, M.; Boone, T.; Dautremont-Smith, W. C.

    1990-04-01

    Low resistance nonalloyed ohmic contacts of e-gun evaporated Pt/Ti to S doped n-InP 5×1017, 1×1018, and 5×1018 cm-3 have been fabricated by rapid thermal processing. The contacts to the lower doped substrates (5×1017 and 1×1018 cm-3) were rectifying as-deposited as well as after heat treatment at temperatures lower than 350 °C. Higher processing temperatures stimulated the Schottky to ohmic contact conversion with minimum specific contact resistance of 1.5×10-5 and 5×10-6 Ω cm2, respectively, as a result of rapid thermal processing at 450 °C for 30 s. Heating at a temperature of 550 °C again yielded a Schottky contact. The contact to the 5×1018 cm-3 InP was ohmic as deposited with a specific contact resistance value of 1.1×10-4 Ω cm2. Supplying heat treatment to the contact caused a decrease of the specific contact resistance to a minimum of 8×10-7 Ω cm2 as a result of rapid thermal processing at 450 °C for 30 s. In all cases, this heat treatment caused a limited interfacial reactions between the Ti and the InP, and resulted in an almost abrupt interface. Heating at temperatures higher than 500 °C resulted in an interfacial intermixing and a mutual migration and reaction of the Ti and the semiconductor elements. The Pt/Ti bilayer structure was highly tensile as deposited (5×109 dyn cm-2) and became stress-free as a result of the interfacial reactions which took place while heating the samples to temperature of 400 °C or higher.

  9. Structures of complexes formed by H5 influenza hemagglutinin with a potent broadly neutralizing human monoclonal antibody

    PubMed Central

    Xiong, Xiaoli; Corti, Davide; Liu, Junfeng; Pinna, Debora; Foglierini, Mathilde; Calder, Lesley J.; Martin, Stephen R.; Lin, Yi Pu; Walker, Philip A.; Collins, Patrick J.; Monne, Isabella; Suguitan, Amorsolo L.; Santos, Celia; Temperton, Nigel J.; Subbarao, Kanta; Lanzavecchia, Antonio; Gamblin, Steven J.; Skehel, John J.

    2015-01-01

    H5N1 avian influenza viruses remain a threat to public health mainly because they can cause severe infections in humans. These viruses are widespread in birds, and they vary in antigenicity forming three major clades and numerous antigenic variants. The most important features of the human monoclonal antibody FLD194 studied here are its broad specificity for all major clades of H5 influenza HAs, its high affinity, and its ability to block virus infection, in vitro and in vivo. As a consequence, this antibody may be suitable for anti-H5 therapy and as a component of stockpiles, together with other antiviral agents, for health authorities to use if an appropriate vaccine was not available. Our mutation and structural analyses indicate that the antibody recognizes a relatively conserved site near the membrane distal tip of HA, near to, but distinct from, the receptor-binding site. Our analyses also suggest that the mechanism of infectivity neutralization involves prevention of receptor recognition as a result of steric hindrance by the Fc part of the antibody. Structural analyses by EM indicate that three Fab fragments are bound to each HA trimer. The structure revealed by X-ray crystallography is of an HA monomer bound by one Fab. The monomer has some similarities to HA in the fusion pH conformation, and the monomer’s formation, which results from the presence of isopropanol in the crystallization solvent, contributes to considerations of the process of change in conformation required for membrane fusion. PMID:26170284

  10. A three-dimensional volume-of-fluid method for reconstructing and advecting three-material interfaces forming contact lines

    NASA Astrophysics Data System (ADS)

    Pathak, Ashish; Raessi, Mehdi

    2016-02-01

    We introduce a piecewise-linear, volume-of-fluid method for reconstructing and advecting three-dimensional interfaces and contact lines formed by three materials. The new method employs a set of geometric constructs that can be used in conjunction with any volume-tracking scheme. In this work, we used the mass-conserving scheme of Youngs to handle two-material cells, perform interface reconstruction in three-material cells, and resolve the contact line. The only information required by the method is the available volume fraction field. Although the proposed method is order dependent and requires a priori information on material ordering, it is suitable for typical contact line applications, where the material representing the contact surface is always known. Following the reconstruction of the contact surface, to compute the interface orientation in a three-material cell, the proposed method minimizes an error function that is based on volume fraction distribution around that cell. As an option, the minimization procedure also allows the user to impose a contact angle. Performance of the proposed method is assessed via both static and advection test cases. The tests show that the new method preserves the accuracy and mass-conserving property of the Youngs method in volume-tracking three materials.

  11. Characterization of the metal-semiconductor interface of gold contacts on CdZnTe formed by electroless deposition

    NASA Astrophysics Data System (ADS)

    Bell, Steven J.; Baker, Mark A.; Duarte, Diana D.; Schneider, Andreas; Seller, Paul; Sellin, Paul J.; Veale, Matthew C.; Wilson, Matthew D.

    2015-06-01

    Fully spectroscopic x/γ-ray imaging is now possible thanks to advances in the growth of wide-bandgap semiconductors. One of the most promising materials is cadmium zinc telluride (CdZnTe or CZT), which has been demonstrated in homeland security, medical imaging, astrophysics and industrial analysis applications. These applications have demanding energy and spatial resolution requirements that are not always met by the metal contacts deposited on the CdZnTe. To improve the contacts, the interface formed between metal and semiconductor during contact deposition must be better understood. Gold has a work function closely matching that of high resistivity CdZnTe and is a popular choice of contact metal. Gold contacts are often formed by electroless deposition however this forms a complex interface. The prior CdZnTe surface preparation, such as mechanical or chemo-mechanical polishing, and electroless deposition parameters, such as gold chloride solution temperature, play important roles in the formation of the interface and are the subject of the presented work. Techniques such as focused ion beam (FIB) cross section imaging, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS) and current  -  voltage (I-V) analysis have been used to characterize the interface. It has been found that the electroless reaction depends on the surface preparation and for chemo-mechanically polished (1 1 1) CdZnTe, it also depends on the A/B face identity. Where the deposition occurred at elevated temperature, the deposited contacts were found to produce a greater leakage current and suffered from increased subsurface voiding due to the formation of cadmium chloride.

  12. Ethanol Extract of Peanut Sprout Exhibits a Potent Anti-Inflammatory Activity in Both an Oxazolone-Induced Contact Dermatitis Mouse Model and Compound 48/80-Treated HaCaT Cells

    PubMed Central

    Choi, Da-In; Choi, Jee-Young; Kim, Young Jee; Lee, Jee-Bum; Kim, Sun-Ouck; Shin, Hyong-Taek

    2015-01-01

    Background We developed an ethanol extract of peanut sprouts (EPS), a peanut sprout-derived natural product, which contains a high level of trans-resveratrol (176.75 µg/ml) and was shown to have potent antioxidant activity. Objective We evaluated the potential anti-inflammatory activity of EPS by measuring its antioxidant potential in skin. Methods The anti-inflammatory activity of EPS was tested using two models of skin inflammation: oxazolone (OX)-induced contact dermatitis in mice and compound 48/80-treated HaCaT cells. As biomarkers of skin inflammation, cyclooxygenase-2 (COX-2) and nerve growth factor (NGF) levels were measured. Results OX-induced contact dermatitis was suppressed markedly in mice that were treated with an ointment containing 5% EPS as evidenced by a decrease in the extent of scaling and thickening (p<0.05) and supported by a histological study. COX-2 (messenger RNA [mRNA] and protein) and NGF (mRNA) levels, which were upregulated in the skin of OX-treated mice, were suppressed markedly in the skin of OX+EPS-treated mice. Consistent with this, compound 48/80-induced expression of COX-2 (mRNA and protein) and NGF (mRNA) in HaCaT cells were suppressed by EPS treatment in a dose-dependent manner. As an inhibitor of NF-κB, IκB protein levels were dose-dependently upregulated by EPS. Fluorescence-activated cell sorting (FACS) analysis revealed that EPS scavenged compound 48/80-induced reactive oxygen species (ROS) in HaCaT cells. Conclusion EPS exerts a potent anti-inflammatory activity via its anti-oxidant activity in both mouse skin and compound 48/80-treated HaCaT cells in vitro. Compound 48/80-treated HaCaT cells are a useful new in vitro model of skin inflammation. PMID:25834352

  13. Lithium fluoride injection layers can form quasi-Ohmic contacts for both holes and electrons

    SciTech Connect

    Bory, Benjamin F.; Janssen, René A. J.; Meskers, Stefan C. J.; Rocha, Paulo R. F.; Gomes, Henrique L.; De Leeuw, Dago M.

    2014-09-22

    Thin LiF interlayers are typically used in organic light-emitting diodes to enhance the electron injection. Here, we show that the effective work function of a contact with a LiF interlayer can be either raised or lowered depending on the history of the applied bias. Formation of quasi-Ohmic contacts for both electrons and holes is demonstrated by electroluminescence from symmetric LiF/polymer/LiF diodes in both bias polarities. The origin of the dynamic switching is charging of electrically induced Frenkel defects. The current density–electroluminescence–voltage characteristics can qualitatively be explained. The interpretation is corroborated by unipolar memristive switching and by bias dependent reflection measurements.

  14. Form, symmetry and packing of biomacromolecules. III. Antigenic, receptor and contact binding sites in picornaviruses.

    PubMed

    Janner, A

    2011-03-01

    The relation between serotype differentiation and crystallographic symmetry, revealed by the contact fingerprint diagrams investigated in Part II [Janner (2010). Acta Cryst. A66, 312-326] for the human rhinovirus, is extended to the Picornaviridae family. The approach, outlined in Part I [Janner (2010). Acta Cryst. A66, 301-311] and Part II for biomacromolecules packed in a crystal and based on concepts such as packing lattice, kissing points and crystal-packing parameters, can directly be applied to the picornaviruses. In particular, the contact fingerprint diagrams of 20 different virus strains have been derived. In these cases, as for the rhinovirus, these diagrams are serotype/strain specific, justifying the name fingerprint. The molecular basis for the serotype variability, and the associated conservation requirements, is usually analysed by considering antigenic sites, where capsid residues bind with antibodies, and receptor sites, where other residues bind with molecular receptors of the host cell membrane. Both the antigenic variation and the receptor conservation allow repeated infection of the host cells of the given animals. The graphical description of these sites is usually done by footprints and roadmap diagrams, mapping properties of the capsid surface and using the icosahedral symmetry of the capsid. The alternative fingerprint diagrammatic description, based on the crystal symmetry, adopted in Part II for the contact sites, where a capsid is bound to the next one in the crystal packing, is extended to the antigenic and receptor binding sites. Again, the antigenic/receptor fingerprints are specific, at least for the nine picornaviruses investigated so far, despite the more than a factor of ten larger coarse graining with respect to the corresponding footprint and roadmap diagrams. The latter are based on a grid spacing of about 2 Å, whereas the spacing implied by the packing-lattice approximation adopted in fingerprints varies typically from 20 to 50 Å. The fingerprint diagrams are accordingly simpler (because approximated), but nevertheless still serotype specific, despite the complex character of the interactions involved. PMID:21325720

  15. Back-contacted and small form factor GaAs solar cell.

    SciTech Connect

    Clews, Peggy Jane; Wanlass, Mark W.; Sanchez, Carlos A.; Pluym, Tammy; Cruz-Campa, Jose Luis; Okandan, Murat; Gupta, Vipin P.; Nielson, Gregory N.; Resnick, Paul James

    2010-07-01

    We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

  16. Effects of the novel and potent lymphocyte-specific protein tyrosine kinase inhibitor TKM0150 on mixed lymphocyte reaction and contact hypersensitivity in mice.

    PubMed

    Takayama, Tetsuo; Takaoka, Akiko; Takahashi, Shuya; Takahashi, Akiko; Umemiya, Hiroki; Sato, Masakazu

    2010-01-01

    Lymphocyte-specific protein tyrosine kinase (Lck) plays a critical role in T cell activation. In the present study, the effect of a newly synthesized small molecule compound, 7-[2-(dimethylamino)ethoxy]-2-(4-phenoxyphenyl)-9,10-dihydro-4H- pyrazolo[5,1-b] [1,3]benzodiazepine-3-carboxamide (TKM0150) on Lck activity was investigated. TKM0150 inhibited Lck with an 1C50 value of 0.7 nM. To evaluate if TKM0150 is a specific inhibitor of Lck, the activity against several Src (Proto-oncogene tyrosine-protein kinase Src) and non-Src family kinases were assayed. TKM150 inhibited Src family kinases, Src and Csk (c-Src kinase) (with IC50 values of 0.6 nM and 1.7 nM, respectively) as well as Fyn (p59-Fyn) and Lyn (tyrosine-protein kinase Lyn) at a dose of 1 microM; however, it did not inhibit kinase which is a non-Src family kinase in the tyrosine kinase (TK) group, nor kinases in other groups. Then, the anti-inflammtory potential of TKM0150 was evaluated by known experimental models. TKM0150 inhibited the murine mixed lymphocyte reaction (MLR) in vitro with an IC50 value of 0.7 nM, and 2,4,6-trinitro-1-chlorobenzene-induced contact hypersensitivity in vivo at a dose of 0.3 and 1% w/v administered topically. These results indicate that TKM0150 is a specific inhibitor of Lck/Src kinase and can block T cell-mediated responses in vitro and in vivo. Accordingly, TKM0150 would be expected as a drug candidate for treating T cell-mediated disorders including atopic dermatitis. PMID:20533766

  17. Moisture Battery Formed by Direct Contact of Magnesium with Foamed Polyaniline.

    PubMed

    Xie, Pu; Rong, Min Zhi; Zhang, Ming Qiu

    2016-01-26

    The present communication reports a concept battery made by direct contact of magnesium foil with ultralight polyaniline (PANI) foam in the absence of additional electrolyte. Electrical current is allowed to be steadily released from the junction with a specific energy of 646 mWh g(-1) and specific capacity of 1247 mAh g(-1). Additionally, the battery offers an environmentally friendly route of hydrogen production along with discharging. Mechanistic studies indicated that the ubiquitous galvanic corrosion combined with decomposition of adsorbed trace water in the semi-conducting polymer foam enabled the generation of electricity, which overturns the traditional view. The higher moisture level is conducive to the discharge. This work is believed to open up new possibilities for the design of electrochemical batteries. PMID:26696566

  18. Auger analysis of films formed on metals in sliding contact with halogenated polymers

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1974-01-01

    The use of Auger electron spectroscopy (AES) to search for transferred polymer must contend with the fact that there has been no published work on Auger analysis of polymers. Since this is a new area for AES, the Auger spectra of polymers and of halogenated polymers in particular is discussed. It is shown that the Auger spectra of halogenated polymers have certain characteristics that permit an assessment of whether a polymeric transfer film has been established by sliding contact. The discussion is general and the concepts should be useful in considering the Auger analysis of any polymer. The polymers chosen for this study are the halogenated polymers polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and polychlorotrifluorethylene (PCTFE).

  19. Observation of current polarity effect in stressing as-formed sub-micron Al-Si-Cu/TiW/TiSi 2 contacts

    NASA Astrophysics Data System (ADS)

    Chen, Li-Zen; Hsu, Klaus Y.-J.

    1999-06-01

    Formation of good silicide contacts becomes more important but difficult as the contact size continues shrinking toward the deep sub-micron regime. At the same time, higher current density, which may easily appear in small regions, could pose strong impact to the long-term reliability of sub-micron contacts. In this work, high current density stress experiments were conducted on the Al-Si-Cu/TiW/TiSi 2 contacts with the size ranging from 0.5×0.5 μm 2 down to 0.25×0.25 μm 2. The self-aligned silicide contacts were formed by using collimated sputtering, E-beam lithography, RTA, and RIE techniques. The silicide contacts were sintered at 400°C for 30 min. Cross-bridge Kelvin resistor structures were formed for electrical stressing and contact resistance measurement. One-way and two-way stressings were performed at high current density (˜10 7 A/cm 2) and the contact resistance was measured periodically at low current density during the stressing to monitor the evolution. It was found that the initial resistance of as-formed contacts was higher than expected. This is probably due to the difficulty of forming good interfaces in the small contact region by sputtering and that the sintering temperature may not be high enough to smear out the imperfection. The stressing was found to anneal the contacts. With electrons flowing from metal layer into the contact window, the contact resistance was reduced more efficiently than with reverse current of the same density. Stressed first by reverse current then by normal current, the resistance showed a two-step reduction with a significant transition at the switch of current polarity. For prolonged stressing, the contacts were gradually degraded and the reverse current induced more severe damage. These observations indicate strong electromigration effect at the small contacts.

  20. Induction of Ca2+-Calmodulin Signaling by Hard-Surface Contact Primes Colletotrichum gloeosporioides Conidia To Germinate and Form Appressoria

    PubMed Central

    Kim, Yeon-Ki; Li, Daoxin; Kolattukudy, Pappachan E.

    1998-01-01

    Hard-surface contact primes the conidia of Colletotrichum gloeosporioides to respond to plant surface waxes and a fruit-ripening hormone, ethylene, to germinate and form the appressoria required for infection of the host. Our efforts to elucidate the molecular events in the early phase of the hard-surface contact found that EGTA (5 mM) and U73122 (16 nM), an inhibitor of phospholipase C, inhibited (50%) germination and appressorium formation. Measurements of calmodulin (CaM) transcripts with a CaM cDNA we cloned from C. gloeosporioides showed that CaM was induced by hard-surface contact maximally at 2 h and then declined; ethephon enhanced this induction. The CaM antagonist, compound 48/80, completely inhibited conidial germination and appressorium formation at a concentration of 3 μM, implying that CaM is involved in this process. A putative CaM kinase (CaMK) cDNA of C. gloeosporioides was cloned with transcripts from hard-surface-treated conidia. A selective inhibitor of CaMK, KN93 (20 μM), inhibited (50%) germination and appressorium formation, blocked melanization, and caused the formation of abnormal appressoria. Scytalone, an intermediate in melanin synthesis, reversed the inhibition of melanization but did not restore appressorium formation. The phosphorylation of 18- and 43-kDa proteins induced by hard-surface contact and ethephon was inhibited by the treatment with KN93. These results strongly suggest that hard-surface contact induces Ca2+-calmodulin signaling that primes the conidia to respond to host signals by germination and differentiation into appressoria. PMID:9748448

  1. Structure of diffusion layers formed at liquid aluminum alloy-steel contact boundary

    NASA Astrophysics Data System (ADS)

    Brodova, I. G.; Chikova, O. A.; Shirinkina, I. G.; Yablonskikh, T. I.; Astaf'ev, V. V.

    2013-05-01

    The microstructure and composition of diffusion layers that arise upon the spread of the liquid aluminum alloys AL5, AL9, AL852, and A7075 over the St3 steel has been investigated using optical and electron microscopy. The thermophysical conditions of the interaction of the melt with the substrate under which at the boundary of the substrate the plastic transition layer of iron-based solid solution improving quality of the coating is formed have been determined.

  2. Experiments and simulations show how long-range contacts can form in expanded unfolded proteins with negligible secondary structure

    PubMed Central

    Meng, Wenli; Lyle, Nicholas; Luan, Bowu; Raleigh, Daniel P.; Pappu, Rohit V.

    2013-01-01

    The sizes of unfolded proteins under highly denaturing conditions scale as N0.59 with chain length. This suggests that denaturing conditions mimic good solvents, whereby the preference for favorable chain–solvent interactions causes intrachain interactions to be repulsive, on average. Beyond this generic inference, the broader implications of N0.59 scaling for quantitative descriptions of denatured state ensembles (DSEs) remain unresolved. Of particular interest is the degree to which N0.59 scaling can simultaneously accommodate intrachain attractions and detectable long-range contacts. Here we present data showing that the DSE of the N-terminal domain of the L9 (NTL9) ribosomal protein in 8.3 M urea lacks detectable secondary structure and forms expanded conformations in accord with the expected N0.59 scaling behavior. Paramagnetic relaxation enhancements, however, indicate the presence of detectable long-range contacts in the denatured-state ensemble of NTL9. To explain these observations we used atomistic thermal unfolding simulations to identify ensembles whose properties are consistent with all of the experimental observations, thus serving as useful proxies for the DSE of NTL9 in 8.3 M urea. Analysis of these ensembles shows that residual attractions are present under mimics of good solvent conditions, and for NTL9 they result from low-likelihood, medium/long-range contacts between hydrophobic residues. Our analysis provides a quantitative framework for the simultaneous observation of N0.59 scaling and low-likelihood long-range contacts for the DSE of NTL9. We propose that such low-likelihood intramolecular hydrophobic clusters might be a generic feature of DSEs that play a gatekeeping role to protect against aggregation during protein folding. PMID:23341588

  3. Influence of a deep-level-defect band formed in a heavily Mg-doped GaN contact layer on the Ni/Au contact to p-GaN

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Jing; Zhao, De-Gang; Jiang, De-Sheng; Chen, Ping; Zhu, Jian-Jun; Liu, Zong-Shun; Le, Ling-Cong; Yang, Jing; He, Xiao-Guang; Zhang, Li-Qun; Liu, Jian-Ping; Zhang, Shu-Ming; Yang, Hui

    2015-09-01

    The influence of a deep-level-defect (DLD) band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN (p++-GaN) contact layer with DLD band can effectively improve the performance of Ni/Au ohmic contact to p-GaN. The temperature-dependent I-V measurement shows that the variable-range hopping (VRH) transportation through the DLD band plays a dominant role in the ohmic contact. The thickness and Mg/Ga flow ratio of p++-GaN contact layer have a significant effect on ohmic contact by controlling the Mg impurity doping and the formation of a proper DLD band. When the thickness of the p++-GaN contact layer is 25 nm thick and the Mg/Ga flow rate ratio is 10.29%, an ohmic contact with low specific contact resistivity of 6.97× 10- 4 Ω·cm2 is achieved. Project supported by the National Natural Science Foundation of China (Grant Nos. 61474110, 61377020, 61376089, 61223005, and 61176126), the National Science Fund for Distinguished Young Scholars of China (Grant No. 60925017), One Hundred Person Project of the Chinese Academy of Sciences, and the Basic Research Project of Jiangsu Province, China (Grant No. BK20130362).

  4. Self-formed copper oxide contact interlayer for high-performance oxide thin film transistors

    SciTech Connect

    Gao, Xu E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya; Mitoma, Nobuhiko; Lin, Meng-Fang; Kizu, Takio; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Nabatame, Toshihide

    2014-07-14

    Oxide thin film transistor employing copper source/drain electrodes shows a small turn on voltage and reduced hysteresis. Cross-sectional high-resolution transmission electron microscopy image confirmed the formation of ∼4 nm CuO{sub x} related interlayer. The lower bond-dissociation energy of Cu-O compared to Si-O and In-O suggests that the interlayer was formed by adsorbing oxygen molecules from surrounding environment instead of getting oxygen atoms from the semiconductor film. The formation of CuO{sub x} interlayer acting as an acceptor could suppress the carrier concentration in the transistor channel, which would be utilized to control the turn on voltage shifts in oxide thin film transistors.

  5. Closed form expressions for sheet resistance and mobility from Van-der-Pauw measurement on 90° symmetric devices with four arbitrary contacts

    NASA Astrophysics Data System (ADS)

    Ausserlechner, Udo

    2016-02-01

    Sheet resistance and Hall mobility are commonly measured by Van der Pauw's method. Closed form expressions are known for four point-sized contacts. Recently, for devices with fourfold rotational symmetry a closed form expression for the sheet resistance was given for contacts of arbitrary size. In this paper we discuss its accuracy, link it to the equivalent circuit diagram of the device, and add another expression that determines the Hall mobility with 0.02% accuracy.

  6. The parapatric distribution and contact zone of two forms showing different male-to-male aggressiveness in a social spider mite, Stigmaeopsis miscanthi (Acari: Tetranychidae).

    PubMed

    Sato, Yukie; Saito, Yutaka; Chittenden, Anthony R

    2008-04-01

    Two forms showing different male-to-male aggressiveness, different male morphologies and different diapause attributes are known in Stigmaeopsis miscanthi (Saito), a social spider mite infesting Chinese silver grass (Miscanthus sinensis Anderss). Reproductive isolation exists between the forms, although it is not always complete, and the details of their distributional patterns are unknown, but expected to be parapatric. We searched for the contact zone at Mt. Unzen (Nagasaki Pref., Japan) where both forms are known to occur at different altitudes. We found the two forms together in several M. sinensis stands, suggesting there is frequent contact between the forms in their boundary area. We discuss the mechanism(s) that maintain the parapatry related to their frequent contact and the pattern of reproductive isolation between them. PMID:18392941

  7. The Troy Microneedle: A Rapidly Separating, Dissolving Microneedle Formed by Cyclic Contact and Drying on the Pillar (CCDP)

    PubMed Central

    Kim, Miroo; Yang, Huisuk; Kim, Suyong; Lee, Chisong; Jung, Hyungil

    2015-01-01

    In dissolving microneedle (DMN)-mediated therapy, complete and rapid delivery of DMNs is critical for the desired efficacy. Traditional patch-based DMN delivery, however, may fail due to incomplete delivery from insufficient skin insertion or rapid separation of microneedles due to their strong bond to the backing film. Here, we introduce the Troy microneedle, which was created by cyclic contact and drying on the pillar (CCDP), and which enabled simultaneous complete and rapid delivery of DMN. This CCDP process could be flexibly repeated to achieve a specific desired drug dose in a DMN. We evaluated DMN separation using agarose gel, and the Troy microneedle achieved more complete and rapid separation than other, more deeply dipped DMN, primarily because of the Troy’s minimal junction between the DMN and pillar. When Troy microneedles were applied to pig cadaver skin, it took only 15 s for over 90% of encapsulated rhodamine B to be delivered, compared to 2 h with application of a traditional DMN patch. In vivo skin penetration studies demonstrated rapid DMN-separation of Troy microneedles still in solid form before dissolution. The Troy microneedle overcomes critical issues associated with the low penetration efficiency of flat patch-based DMN and provides an innovative route for DMN-mediated therapy, combining patient convenience with the desire drug efficacy. PMID:26308945

  8. The comparison between two irrigation regimens on the dentine wettability for an epoxy resin based sealer by measuring its contact angle formed to the irrigated dentine

    PubMed Central

    Mohan, Rayapudi Phani; Pai, Annappa Raghavendra Vivekananda

    2015-01-01

    Aim: The aim was to assess the influence of two irrigation regimens having ethylenediaminetetraacetic acid (EDTA) and ethylenediaminetetraacetic acid with cetrimide (EDTAC) as final irrigants, respectively, on the dentine wettability for AH Plus sealer by comparing its contact angle formed to the irrigated dentine. Materials and Methods: Study samples were divided into two groups (n = 10). The groups were irrigated with 3% sodium hypochlorite (NaOCl) solution followed by either 17% EDTA or 17% EDTAC solution. AH Plus was mixed, and controlled volume droplet (0.1 mL) of the sealer was placed on the dried samples. The contact angle was measured using a Dynamic Contact Angle Analyzer and results were analyzed using SPSS 21.0 and 2 sample t-test. Results: There was a significant difference in the contact angle of AH Plus formed to the dentine irrigated with the above two regimens. AH Plus showed significantly lower contact angle with the regimen having EDTAC as a final irrigant than the one with EDTA (P < 0.05). Conclusion: An irrigation regimen consisting of NaOCl with either EDTA or EDTAC solution as a final irrigant influences the dentine wettability and contact angle of a sealer. EDTAC as a final irrigant facilitates better dentin wettability than EDTA for AH Plus to promote its better flow and adhesion. PMID:26180409

  9. Modeling of contact theories for the manipulation of biological micro/nanoparticles in the form of circular crowned rollers based on the atomic force microscope

    SciTech Connect

    Korayem, M. H.; Khaksar, H.; Taheri, M.

    2013-11-14

    This article has dealt with the development and modeling of various contact theories for biological nanoparticles shaped as cylinders and circular crowned rollers for application in the manipulation of different biological micro/nanoparticles based on Atomic Force Microscope. First, the effective contact forces were simulated, and their impact on contact mechanics simulation was investigated. In the next step, the Hertz contact model was simulated and compared for gold and DNA nanoparticles with the three types of spherical, cylindrical, and circular crowned roller type contact geometries. Then by reducing the length of the cylindrical section in the circular crowned roller geometry, the geometry of the body was made to approach that of a sphere, and the results were compared for DNA nanoparticles. To anticipatory validate the developed theories, the results of the cylindrical and the circular crowned roller contacts were compared with the results of the existing spherical contact simulations. Following the development of these contact models for the manipulation of various biological micro/nanoparticles, the cylindrical and the circular crowned roller type contact theories were modeled based on the theories of Lundberg, Dowson, Nikpur, Heoprich, and Hertz for the manipulation of biological micro/nanoparticles. Then, for a more accurate validation, the results obtained from the simulations were compared with those obtained by the finite element method and with the experimental results available in previous articles. The previous research works on the simulation of nanomanipulation have mainly investigated the contact theories used in the manipulation of spherical micro/nanoparticles. However since in real biomanipulation situations, biological micro/nanoparticles of more complex shapes need to be displaced in biological environments, this article therefore has modeled and compared, for the first time, different contact theories for use in the biomanipulation of cylindrical and circular crowned roller shaped micro/nanoparticles. The results of models indicate that the contact model of Hertz achieves the largest amount of deformation for the DNA nanoparticle in cylindrical form and the contact model of Heoprich achieves the largest deformation for the circular crowned roller shaped DNA. Of course, this finding is not always true for the other nanoparticles; and considering the mechanical and environmental characteristics, different results can be obtained. Also, by comparing the deformations of different types of nanoparticles, it was determined that the platelet type nanoparticles display the highest degree of deformation in all the considered models, due to their particular mechanical characteristics.

  10. Modeling of contact theories for the manipulation of biological micro/nanoparticles in the form of circular crowned rollers based on the atomic force microscope

    NASA Astrophysics Data System (ADS)

    Korayem, M. H.; Khaksar, H.; Taheri, M.

    2013-11-01

    This article has dealt with the development and modeling of various contact theories for biological nanoparticles shaped as cylinders and circular crowned rollers for application in the manipulation of different biological micro/nanoparticles based on Atomic Force Microscope. First, the effective contact forces were simulated, and their impact on contact mechanics simulation was investigated. In the next step, the Hertz contact model was simulated and compared for gold and DNA nanoparticles with the three types of spherical, cylindrical, and circular crowned roller type contact geometries. Then by reducing the length of the cylindrical section in the circular crowned roller geometry, the geometry of the body was made to approach that of a sphere, and the results were compared for DNA nanoparticles. To anticipatory validate the developed theories, the results of the cylindrical and the circular crowned roller contacts were compared with the results of the existing spherical contact simulations. Following the development of these contact models for the manipulation of various biological micro/nanoparticles, the cylindrical and the circular crowned roller type contact theories were modeled based on the theories of Lundberg, Dowson, Nikpur, Heoprich, and Hertz for the manipulation of biological micro/nanoparticles. Then, for a more accurate validation, the results obtained from the simulations were compared with those obtained by the finite element method and with the experimental results available in previous articles. The previous research works on the simulation of nanomanipulation have mainly investigated the contact theories used in the manipulation of spherical micro/nanoparticles. However since in real biomanipulation situations, biological micro/nanoparticles of more complex shapes need to be displaced in biological environments, this article therefore has modeled and compared, for the first time, different contact theories for use in the biomanipulation of cylindrical and circular crowned roller shaped micro/nanoparticles. The results of models indicate that the contact model of Hertz achieves the largest amount of deformation for the DNA nanoparticle in cylindrical form and the contact model of Heoprich achieves the largest deformation for the circular crowned roller shaped DNA. Of course, this finding is not always true for the other nanoparticles; and considering the mechanical and environmental characteristics, different results can be obtained. Also, by comparing the deformations of different types of nanoparticles, it was determined that the platelet type nanoparticles display the highest degree of deformation in all the considered models, due to their particular mechanical characteristics.

  11. Structural and electrical characterization of silicided Ni/Au contacts formed at low temperature (<300 °C) on p-type [001] silicon

    NASA Astrophysics Data System (ADS)

    Alberti, A.; Badalà, P.; Pellegrino, G.; Santangelo, A.

    2011-12-01

    Silicided Ni/Au contacts with very low contact resistance were realized on p-type [001] silicon at low temperature by ex-situ or, alternatively, by in situ annealing processes. During the ex-situ annealing, performed at 200 °C for 10 s, a uniformly thin (14 nm) Ni2Si layer was formed having an extremely flat interface with silicon thanks to the trans-rotational structure of the silicide. During the in situ annealing, promoted by a sputter etch processing (T < 300 °C), a 44 nm-thick silicide layer was formed as a mixture of trans-rotational NiSi and epitaxial NiSi2, domains. In both cases, using a low thermal budget has guaranteed a limited consumption of silicon during the reaction process and a good adhesion with the substrate avoiding gold contaminations. As a consequence of the presence of trans-rotational domains, wherein a pseudo-epitaxial relationship between the silicide and the silicon lattices is established, an ohmic behavior was observed in a wide range of substrate doping (3.5 × 1018 ÷ 3 × 1019 B/cm3) for both annealing processes (in situ and ex-situ). On the other hand, conventional TiNiAu and CrNiAu contacts showed, in the same range of B doping concentration, a rectifying behavior with systematically higher specific contact resistance values (Rc) compared to those of the Ni silicided contacts.

  12. Boron trichloride plasma treatment effect on ohmic contact resistance formed on GaN-based epitaxial structure

    NASA Astrophysics Data System (ADS)

    Kobelev, A. A.; Barsukov, Yu V.; Andrianov, N. A.; Smirnov, A. S.

    2015-01-01

    A BCl3 plasma treatment effect on GaN surface and reduction of ohmic contact resistance in GaN/AlGaN epitaxial structure with a GaN cap layer has been studied. The BCl3 plasma treatment was carried out by an inductively coupled plasma reactive ion etching (ICP RIE) system under conditions of low discharge power with zero external bias controlling power to prevent any recess etching of the GaN cap layer. The measured average contact resistances with and without plasma treatment were 1.8×10-5 and 1.05×10-5 Ω·cm2 respectively. To study the BCl3 plasma treatment effect on GaN surface and explain the increasing of contact resistance, the elemental composition of GaN surface was measured using x-ray photoelectron spectroscopy. It was found that a Bx-Cly layer covered the GaN surface after the BCl3 plasma treatment. This can indicate that ion bombardment from plasma is inefficient to prevent deposition of BClx radicals on the GaN cap layer surface and subsequent formation of the Bx-Cly layer which is responsible for increase of ohmic contact resistance after the BCl3 plasma treatment.

  13. Use of separate ZnTe interface layers to form OHMIC contacts to p-CdTe films

    DOEpatents

    Gessert, Timothy A.

    1999-01-01

    A method of improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurim-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact.

  14. Use of separate ZnTe interface layers to form ohmic contacts to p-CdTe films

    DOEpatents

    Gessert, T.A.

    1999-06-01

    A method of is disclosed improving electrical contact to a thin film of a p-type tellurium-containing II-VI semiconductor comprising: depositing a first undoped layer of ZnTe on a thin film of p-type tellurium containing II-VI semiconductor with material properties selected to limit the formation of potential barriers at the interface between the p-CdTe and the undoped layer, to a thickness sufficient to control diffusion of the metallic-doped ZnTe into the p-type tellurium-containing II-VI semiconductor, but thin enough to minimize affects of series resistance; depositing a second heavy doped p-type ZnTe layer to the first layer using an appropriate dopant; and depositing an appropriate metal onto the outer-most surface of the doped ZnTe layer for connecting an external electrical conductor to an ohmic contact. 11 figs.

  15. Structure of Apo- and Monometalated Forms of NDM-1—A Highly Potent Carbapenem-Hydrolyzing Metallo-β-Lactamase

    PubMed Central

    Kim, Youngchang; Sacchettini, James; Joachimiak, Andrzej

    2011-01-01

    The New Delhi Metallo-β-lactamase (NDM-1) gene makes multiple pathogenic microorganisms resistant to all known β-lactam antibiotics. The rapid emergence of NDM-1 has been linked to mobile plasmids that move between different strains resulting in world-wide dissemination. Biochemical studies revealed that NDM-1 is capable of efficiently hydrolyzing a wide range of β-lactams, including many carbapenems considered as “last resort” antibiotics. The crystal structures of metal-free apo- and monozinc forms of NDM-1 presented here revealed an enlarged and flexible active site of class B1 metallo-β-lactamase. This site is capable of accommodating many β-lactam substrates by having many of the catalytic residues on flexible loops, which explains the observed extended spectrum activity of this zinc dependent β-lactamase. Indeed, five loops contribute “keg” residues in the active site including side chains involved in metal binding. Loop 1 in particular, shows conformational flexibility, apparently related to the acceptance and positioning of substrates for cleavage by a zinc-activated water molecule. PMID:21931780

  16. Durable contact active antimicrobial materials formed by a one-step covalent modification of polyvinyl alcohol, cellulose and glass surfaces.

    PubMed

    Poverenov, Elena; Shemesh, Moshe; Gulino, Antonino; Cristaldi, Domenico A; Zakin, Varda; Yefremov, Tatiana; Granit, Rina

    2013-12-01

    In this work we have applied a direct covalent linkage of quaternary ammonium salts (QAS) to prepare a series of contact active antimicrobial surfaces based on widely utilized materials. Formation of antimicrobial polyvinyl alcohol (PVA-QAS), cellulose (cellulose-QAS) and glass (glass-QAS) surfaces was achieved by one step synthesis with no auxiliary linkers. The X-ray photoelectron spectroscopy (XPS) revealed tridentate binding mode of the antimicrobial agent. The antimicrobial activity of the prepared materials was tested on Bacillus cereus, Alicyclobacillus acidoterrestris, Escherichia coli and Pseudomonas aeruginosa. Active site density of the modified materials was examined and found to correlate with their antimicrobial activity. Stability studies at different pH values and temperatures confirmed that the linkage of the bioactive moiety to the surface is robust and resistant to a range of pH and temperatures. Prolonged long-term effectiveness of the contact active materials was demonstrated by their repeated usage, without loss of the antimicrobial efficacy. PMID:24012705

  17. First-principles investigation on the electronic efficiency and binding energy of the contacts formed by graphene and poly-aromatic hydrocarbon anchoring groups

    NASA Astrophysics Data System (ADS)

    Li, Yang; Tu, Xingchen; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-04-01

    The electronic efficiency and binding energy of contacts formed between graphene electrodes and poly-aromatic hydrocarbon (PAH) anchoring groups have been investigated by the non-equilibrium Green's function formalism combined with density functional theory. Our calculations show that PAH molecules always bind in the interior and at the edge of graphene in the AB stacking manner, and that the binding energy increases following the increase of the number of carbon and hydrogen atoms constituting the PAH molecule. When we move to analyzing the electronic transport properties of molecular junctions with a six-carbon alkyne chain as the central molecule, the electronic efficiency of the graphene-PAH contacts is found to depend on the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the corresponding PAH anchoring group, rather than its size. To be specific, the smaller is the HOMO-LUMO gap of the PAH anchoring group, the higher is the electronic efficiency of the graphene-PAH contact. Although the HOMO-LUMO gap of a PAH molecule depends on its specific configuration, PAH molecules with similar atomic structures show a decreasing trend for their HOMO-LUMO gap as the number of fused benzene rings increases. Therefore, graphene-conjugated molecule-graphene junctions with high-binding and high-conducting graphene-PAH contacts can be realized by choosing appropriate PAH anchor groups with a large area and a small HOMO-LUMO gap.

  18. First-principles investigation on the electronic efficiency and binding energy of the contacts formed by graphene and poly-aromatic hydrocarbon anchoring groups

    SciTech Connect

    Li, Yang; Tu, Xingchen; Wang, Hao; Hou, Shimin; Sanvito, Stefano

    2015-04-28

    The electronic efficiency and binding energy of contacts formed between graphene electrodes and poly-aromatic hydrocarbon (PAH) anchoring groups have been investigated by the non-equilibrium Green’s function formalism combined with density functional theory. Our calculations show that PAH molecules always bind in the interior and at the edge of graphene in the AB stacking manner, and that the binding energy increases following the increase of the number of carbon and hydrogen atoms constituting the PAH molecule. When we move to analyzing the electronic transport properties of molecular junctions with a six-carbon alkyne chain as the central molecule, the electronic efficiency of the graphene-PAH contacts is found to depend on the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the corresponding PAH anchoring group, rather than its size. To be specific, the smaller is the HOMO-LUMO gap of the PAH anchoring group, the higher is the electronic efficiency of the graphene-PAH contact. Although the HOMO-LUMO gap of a PAH molecule depends on its specific configuration, PAH molecules with similar atomic structures show a decreasing trend for their HOMO-LUMO gap as the number of fused benzene rings increases. Therefore, graphene-conjugated molecule-graphene junctions with high-binding and high-conducting graphene-PAH contacts can be realized by choosing appropriate PAH anchor groups with a large area and a small HOMO-LUMO gap.

  19. Ultraviolet band-pass Schottky barrier photodetectors formed by Al-doped ZnO contacts to n-GaN

    SciTech Connect

    Sheu, J.K.; Lee, M.L.; Tun, C.J.; Lin, S.W.

    2006-01-23

    This work prepared Al-doped ZnO(AZO) films using dc sputtering to form Schottky contacts onto GaN films with low-temperature-grown GaN cap layer. Application of ultraviolet photodetector showed that spectral responsivity exhibits a narrow bandpass characteristic ranging from 345 to 375 nm. Moreover, unbiased peak responsivity was estimated to be around 0.12 A/W at 365 nm, which corresponds to a quantum efficiency of around 40%. In our study, relatively low responsivity can be explained by the marked absorption of the AZO contact layer. When the reverse biases were below 5 V, the study revealed that dark currents were well below 5x10{sup -12} A even though the samples were annealed at increased temperatures.

  20. A flexible proximity sensor formed by duplex screen/screen-offset printing and its application to non-contact detection of human breathing

    NASA Astrophysics Data System (ADS)

    Nomura, Ken-Ichi; Kaji, Ryosaku; Iwata, Shiro; Otao, Shinobu; Imawaka, Naoto; Yoshino, Katsumi; Mitsui, Ryosuke; Sato, Junya; Takahashi, Seiya; Nakajima, Shin-Ichiro; Ushijima, Hirobumi

    2016-01-01

    We describe a flexible capacitance-type sensor that can detect an approaching human without contact, fabricated by developing and applying duplex conductive-ink printing to a film substrate. The results of our calculations show that the difference in size between the top and bottom electrodes of the sensor allows for the spatial extension of the electric field distribution over the electrodes. Hence, such a component functions as a proximity sensor. This thin and light device with a large form factor can be arranged at various places, including curved surfaces and the back of objects such that it is unnoticeable. In our experiment, we attached it to the back of a bed, and found that our device successfully detected the breathing of a subject on the bed without contacting his body. This should contribute to reducing the physical and psychological discomfort among patients during medical checks, or when their condition is being monitored.

  1. A flexible proximity sensor formed by duplex screen/screen-offset printing and its application to non-contact detection of human breathing

    PubMed Central

    Nomura, Ken-ichi; Kaji, Ryosaku; Iwata, Shiro; Otao, Shinobu; Imawaka, Naoto; Yoshino, Katsumi; Mitsui, Ryosuke; Sato, Junya; Takahashi, Seiya; Nakajima, Shin-ichiro; Ushijima, Hirobumi

    2016-01-01

    We describe a flexible capacitance-type sensor that can detect an approaching human without contact, fabricated by developing and applying duplex conductive-ink printing to a film substrate. The results of our calculations show that the difference in size between the top and bottom electrodes of the sensor allows for the spatial extension of the electric field distribution over the electrodes. Hence, such a component functions as a proximity sensor. This thin and light device with a large form factor can be arranged at various places, including curved surfaces and the back of objects such that it is unnoticeable. In our experiment, we attached it to the back of a bed, and found that our device successfully detected the breathing of a subject on the bed without contacting his body. This should contribute to reducing the physical and psychological discomfort among patients during medical checks, or when their condition is being monitored. PMID:26795237

  2. A flexible proximity sensor formed by duplex screen/screen-offset printing and its application to non-contact detection of human breathing.

    PubMed

    Nomura, Ken-Ichi; Kaji, Ryosaku; Iwata, Shiro; Otao, Shinobu; Imawaka, Naoto; Yoshino, Katsumi; Mitsui, Ryosuke; Sato, Junya; Takahashi, Seiya; Nakajima, Shin-Ichiro; Ushijima, Hirobumi

    2016-01-01

    We describe a flexible capacitance-type sensor that can detect an approaching human without contact, fabricated by developing and applying duplex conductive-ink printing to a film substrate. The results of our calculations show that the difference in size between the top and bottom electrodes of the sensor allows for the spatial extension of the electric field distribution over the electrodes. Hence, such a component functions as a proximity sensor. This thin and light device with a large form factor can be arranged at various places, including curved surfaces and the back of objects such that it is unnoticeable. In our experiment, we attached it to the back of a bed, and found that our device successfully detected the breathing of a subject on the bed without contacting his body. This should contribute to reducing the physical and psychological discomfort among patients during medical checks, or when their condition is being monitored. PMID:26795237

  3. Contact dermatitis

    MedlinePlus

    Dermatitis - contact; Allergic dermatitis; Dermatitis - allergic; Irritant contact dermatitis; Skin rash - contact dermatitis ... There are 2 types of contact dermatitis. Irritant dermatitis: This ... can be by contact with acids, alkaline materials such as soaps ...

  4. The relative noise levels of parallel axis gear sets with various contact ratios and gear tooth forms

    NASA Technical Reports Server (NTRS)

    Drago, Raymond J.; Lenski, Joseph W., Jr.; Spencer, Robert H.; Valco, Mark; Oswald, Fred B.

    1993-01-01

    The real noise reduction benefits which may be obtained through the use of one gear tooth form as compared to another is an important design parameter for any geared system, especially for helicopters in which both weight and reliability are very important factors. This paper describes the design and testing of nine sets of gears which are as identical as possible except for their basic tooth geometry. Noise measurements were made at various combinations of load and speed for each gear set so that direct comparisons could be made. The resultant data was analyzed so that valid conclusions could be drawn and interpreted for design use.

  5. Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System.

    PubMed

    Lavrynenko, O M; Pavlenko, O Yu; Shchukin, Yu S

    2016-12-01

    The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations. PMID:26847693

  6. Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System

    NASA Astrophysics Data System (ADS)

    Lavrynenko, O. M.; Pavlenko, O. Yu; Shchukin, Yu S.

    2016-02-01

    The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations.

  7. Nanosulfur: A Potent Fungicide Against Food Pathogen, Aspergillus niger

    SciTech Connect

    Choudhury, Samrat Roy; Goswami, Arunava; Nair, Kishore K.; Kumar, Rajesh; Gopal, Madhuban; Devakumar, C.; Gogoi, Robin; Srivastava, Chitra; Subhramanyam, B. S.

    2010-10-04

    Elemental sulfur (S{sup 0}), man's oldest eco-friendly fungicide for curing fungal infections in plants and animals, is registered in India as a non-systemic and contact fungicide. However due to its high volume requirement, Indian agrochemical industry and farmers could not effectively use this product till date. We hypothesize that intelligent nanoscience applications might increase the visibility of nanosulfur in Indian agriculture as a potent and eco-safe fungicide. Sulfur nanoparticles (NPs) were synthesized bottom-up via a liquid synthesis method with average particle size in the range of 50-80 nm and the shapes of the NPs were spherical. A comparative study of elemental and nano-sulfur produced has been tested against facultative fungal food pathogen, Aspergillus niger. Results showed that nanosulfur is more efficacious than its elemental form.

  8. Nanosulfur: A Potent Fungicide Against Food Pathogen, Aspergillus niger

    NASA Astrophysics Data System (ADS)

    Choudhury, Samrat Roy; Nair, Kishore K.; Kumar, Rajesh; Gogoi, Robin; Srivastava, Chitra; Gopal, Madhuban; Subhramanyam, B. S.; devakumar, C.; Goswami, Arunava

    2010-10-01

    Elemental sulfur (S0), man's oldest eco-friendly fungicide for curing fungal infections in plants and animals, is registered in India as a non-systemic and contact fungicide. However due to its high volume requirement, Indian agrochemical industry and farmers could not effectively use this product till date. We hypothesize that intelligent nanoscience applications might increase the visibility of nanosulfur in Indian agriculture as a potent and eco-safe fungicide. Sulfur nanoparticles (NPs) were synthesized bottom-up via a liquid synthesis method with average particle size in the range of 50-80 nm and the shapes of the NPs were spherical. A comparative study of elemental and nano-sulfur produced has been tested against facultative fungal food pathogen, Aspergillus niger. Results showed that nanosulfur is more efficacious than its elemental form.

  9. XANES-EXAFS analysis of se solid-phase reaction products formed upon contacting Se(IV) with FeS2 and FeS.

    PubMed

    Breynaert, E; Bruggeman, C; Maes, A

    2008-05-15

    The solid-phase Se speciation after short-term (3 weeks) contact of selenite [Se(IV)] oxyanions with pyrite (FeS2) and troilite (FeS) was investigated using X-ray absorption spectroscopy (XAS; X-ray absorption near-edge spectroscopy-extended X-ray absorption fine structure (XANES-EXAFS)). It was found that the nature of the sulfide mineral dictates the final speciation since respectively Se(0) and FeSe(x) were formed, meaning that the reaction mechanism is different and that these phases cannot be regarded as geochemically similar. The experimental results support the previously proposed sorption/ reduction mechanism for the reaction of selenite with pyrite. In the presence of troilite the reduction proceeds through the intermediate formation of Se(0) by reduction of selenite with dissolved sulfide. XAS data recorded for the FeS2 and FeS were compared with different Se reference phases, ranging in oxidation state from -II to +IV, used for validation of the XAS analysis methodology. This methodology can in principle be used to analyze Se phases formed in "in situ" geochemical conditions such as high-level radioactive waste disposal facilities. PMID:18546695

  10. The determination of phases formed in AlSiCu/TiN/Ti contact metallization structure of integrated circuits by x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Fortin, V.; Gagnon, G.; Caron, M.; Gujrathi, S. C.; Currie, J. F.; Ouellet, L.; Tremblay, Y.; Biberger, M.

    1998-01-01

    X-ray diffraction (XRD) analysis was performed in order to determine the crystallographic phases formed in AlSiCu/TiN/Ti contact metallization multilayers of very large scale integration/ultralarge scale integration devices deposited over SiO2 and Si substrates as a function of the annealing temperatures, the oxidation treatment of the TiN diffusion barrier, the presence of a TiN antireflective coating (ARC) and the barrier thickness. The most striking results of this study are the formation of the Ti7Al5Si12 phase and the recrystallization of Al after a 550 °C annealing for a nonoxidized 50 nm TiN barrier deposited on Si substrate. This Ti7Al5Si12 phase formation and the Al recrystallization tend to be blocked when an oxidized TiN barrier is used. It is also suggested that an air break process tends to lower the junction spiking problems since Ti7Al5Si12 is believed to be detrimental to the contact metallization layers. These effects were very weak for the 95-nm-thick TiN barrier. In addition, a TiN-ARC layer reduces the Al recrystallization on SiO2 substrate. Even after an important Ti7Al5Si12 formation, the transmission electron microscopy results showed that a TiN layer is still present but probably ineffective from an electrical point of view. Although the 550 °C anneal produced important changes, no significant difference was observed between the XRD spectra after a 450 and a 500 °C anneal. The identified phases by the XRD analysis were in agreement with a calculated Al-Ti-O-N quaternary isotherm diagram.

  11. Muon radiography and deformation analysis of the lava dome formed by the 1944 eruption of Usu, Hokkaido--contact between high-energy physics and volcano physics--.

    PubMed

    K M Tanaka, Hiroyuki; Yokoyama, Izumi

    2008-01-01

    Lava domes are one of the conspicuous topographic features on volcanoes. The subsurface structure of the lava dome is important to discuss its formation mechanism. In the 1944 eruption of Volcano Usu, Hokkaido, a new lava dome was formed at its eastern foot. After the completion of the lava dome, various geophysical methods were applied to the dome to study its subsurface structure, but resulted in a rather ambiguous conclusion. Recently, from the results of the levelings, which were repeated during the eruption, "pseudo growth curves" of the lava dome were obtained. The curves suggest that the lava dome has a bulbous shape. In the present work, muon radiography, which previously proved effective in imaging the internal structure of Volcano Asama, has been applied to the Usu lava dome. The muon radiography measures the distribution of the "density length" of volcanic bodies when detectors are arranged properly. The result obtained is consistent with the model deduced from the pseudo growth curves. The measurement appears to afford useful method to clarify the subsurface structure of volcanoes and its temporal changes, and in its turn to discuss volcanic processes. This is a point of contact between high-energy physics and volcano physics. PMID:18941290

  12. Muon radiography and deformation analysis of the lava dome formed by the 1944 eruption of Usu, Hokkaido —Contact between high-energy physics and volcano physics—

    PubMed Central

    TANAKA, Hiroyuki K. M.; YOKOYAMA, Izumi

    2008-01-01

    Lava domes are one of the conspicuous topographic features on volcanoes. The subsurface structure of the lava dome is important to discuss its formation mechanism. In the 1944 eruption of Volcano Usu, Hokkaido, a new lava dome was formed at its eastern foot. After the completion of the lava dome, various geophysical methods were applied to the dome to study its subsurface structure, but resulted in a rather ambiguous conclusion. Recently, from the results of the levelings, which were repeated during the eruption, “pseudo growth curves” of the lava dome were obtained. The curves suggest that the lava dome has a bulbous shape. In the present work, muon radiography, which previously proved effective in imaging the internal structure of Volcano Asama, has been applied to the Usu lava dome. The muon radiography measures the distribution of the “density length” of volcanic bodies when detectors are arranged properly. The result obtained is consistent with the model deduced from the pseudo growth curves. The measurement appears to afford useful method to clarify the subsurface structure of volcanoes and its temporal changes, and in its turn to discuss volcanic processes. This is a point of contact between high-energy physics and volcano physics. PMID:18941290

  13. Generation of a Potent Low Density Lipoprotein Receptor-related Protein 1 (LRP1) Antagonist by Engineering a Stable Form of the Receptor-associated Protein (RAP) D3 Domain.

    PubMed

    Prasad, Joni M; Migliorini, Mary; Galisteo, Rebeca; Strickland, Dudley K

    2015-07-10

    The low density lipoprotein receptor-related protein 1 (LRP1) is a member of the low density lipoprotein receptor family and plays important roles in a number of physiological and pathological processes. Expression of LRP1 requires the receptor-associated protein (RAP), a molecular chaperone that binds LRP1 and other low density lipoprotein receptor family members in the endoplasmic reticulum and traffics with them to the Golgi where the acidic environment causes its dissociation. Exogenously added RAP is a potent LRP1 antagonist and binds to LRP1 on the cell surface, preventing ligands from binding. Following endocytosis, RAP dissociates in the acidic endosome, allowing LRP1 to recycle back to the cell surface. The acid-induced dissociation of RAP is mediated by its D3 domain, a relatively unstable three-helical bundle that denatures at pH <6.2 due to protonation of key histidine residues on helices 2 and 3. To develop an LRP1 inhibitor that does not dissociate at low pH, we introduced a disulfide bond between the second and third helices in the RAP D3 domain. By combining this disulfide bond with elimination of key histidine residues, we generated a stable RAP molecule that is resistant to both pH- and heat-induced denaturation. This molecule bound to LRP1 with high affinity at both neutral and acidic pH and proved to be a potent inhibitor of LRP1 function both in vitro and in vivo, suggesting that our stable RAP molecule may be useful in multiple pathological settings where LRP1 blockade has been shown to be effective. PMID:26013822

  14. Highly potent silver-organoalkoxysilane antimicrobial porous nanomembrane.

    PubMed

    Umar, Sirajo; Liu, Yuanfeng; Wu, Yiguang; Li, Guangtao; Ding, Jiabo; Xiong, Runsong; Chen, Jinchun

    2013-01-01

    We used a simple electrospinning technique to fabricate a highly potent silver-organoalkoxysilane antimicrobial composite from AgNO3-polyvinylpyrrolidone (PVP)/3-aminopropyltrimethoxysilane (APTMS)/tetraethoxysilane (TEOS) solution. Spectroscopic and microscopic analyses of the composite showed that the fibers contain an organoalkoxysilane 'skeleton,' 0.18 molecules/nm2 surface amino groups, and highly dispersed and uniformly distributed silver nanoparticles (5 nm in size). Incorporation of organoalkoxysilanes is highly beneficial to the antimicrobial mat as (1) amino groups of APTMS are adhesive and biocidal to microorganisms, (2) polycondensation of APTMS and TEOS increases the membrane's surface area by forming silicon bonds that stabilize fibers and form a composite mat with membranous structure and high porosity, and (3) the organoalkoxysilanes are also instrumental to the synthesis of the very small-sized and highly dispersed silver metal particles in the fiber mat. Antimicrobial property of the composite was evaluated by disk diffusion, minimum inhibition concentration (MIC), kinetic, and extended use assays on bacteria (Escherichia coli, Bacillus anthracis, Staphylococcus aureus, and Brucella suis), a fungus (Aspergillus niger), and the Newcastle disease virus. The membrane shows quick and sustained broad-spectrum antimicrobial activity. Only 0.3 mg of fibers is required to achieve MIC against all the test organisms. Bacteria are inhibited within 30 min of contact, and the fibers can be used repeatedly. The composite is silver efficient and environment friendly, and its membranous structure is suitable for many practical applications as in air filters, antimicrobial linen, coatings, bioadhesives, and biofilms. PMID:23574791

  15. Highly potent silver-organoalkoxysilane antimicrobial porous nanomembrane

    NASA Astrophysics Data System (ADS)

    Umar, Sirajo; Liu, Yuanfeng; Wu, Yiguang; Li, Guangtao; Ding, Jiabo; Xiong, Runsong; Chen, Jinchun

    2013-04-01

    We used a simple electrospinning technique to fabricate a highly potent silver-organoalkoxysilane antimicrobial composite from AgNO3-polyvinylpyrrolidone (PVP)/3-aminopropyltrimethoxysilane (APTMS)/tetraethoxysilane (TEOS) solution. Spectroscopic and microscopic analyses of the composite showed that the fibers contain an organoalkoxysilane `skeleton,' 0.18 molecules/nm2 surface amino groups, and highly dispersed and uniformly distributed silver nanoparticles (5 nm in size). Incorporation of organoalkoxysilanes is highly beneficial to the antimicrobial mat as (1) amino groups of APTMS are adhesive and biocidal to microorganisms, (2) polycondensation of APTMS and TEOS increases the membrane's surface area by forming silicon bonds that stabilize fibers and form a composite mat with membranous structure and high porosity, and (3) the organoalkoxysilanes are also instrumental to the synthesis of the very small-sized and highly dispersed silver metal particles in the fiber mat. Antimicrobial property of the composite was evaluated by disk diffusion, minimum inhibition concentration (MIC), kinetic, and extended use assays on bacteria (Escherichia coli, Bacillus anthracis, Staphylococcus aureus, and Brucella suis), a fungus (Aspergillus niger), and the Newcastle disease virus. The membrane shows quick and sustained broad-spectrum antimicrobial activity. Only 0.3 mg of fibers is required to achieve MIC against all the test organisms. Bacteria are inhibited within 30 min of contact, and the fibers can be used repeatedly. The composite is silver efficient and environment friendly, and its membranous structure is suitable for many practical applications as in air filters, antimicrobial linen, coatings, bioadhesives, and biofilms.

  16. Electrical, chemical, and structural characterization of the interface formed between nickel/gold and palladium/gold ohmic contacts and cleaned p-type gallium nitride (0001) surfaces

    NASA Astrophysics Data System (ADS)

    Hartlieb, Philip John

    2002-09-01

    Characterization of pre-treated, Mg-doped, p-type GaN(0001) surfaces and Ni/Au and Pd/Au contact structures sequentially deposited on these surfaces has been conducted using X-ray and ultra-violet photoelectron spectroscopies, low energy electron diffraction, atomic force microscopy, scanning electron microscopy, X-ray diffraction, and current-voltage measurements. The effects or several in-situ cleaning techniques, including vacuum annealing, high-temperature nitrogen plasma pre-treatment, and ammonia-based chemical vapor cleaning, on the chemical and electronic properties of the GaN surface have also been assessed. The last technique was the most effective. Stoichiometric surfaces without detectable carbon and an 87% reduction in the surface oxygen to 2 +/- 1 at% were achieved. The band bending and electron affinity at the cleaned surface were within the ranges of 0.7--1.5eV and 2.5--3.2eV, respectively. Ni/Au contact structures deposited on both vacuum annealed and chemical vapor cleaned p-type GaN surfaces and Pd/Au contacts deposited on a chemical vapor cleaned surface were significantly less rectifying than identical contact structures deposited on conventional HCl treated surfaces, as evidenced by larger currents at equivalent voltages in the former two structures. The room temperature specific contact resistivity of these contacts deposited on vacuum annealed surfaces increased from 0.14 +/- 0.04 O•cm 2 to 0.30 +/- 0.04 O•cm2 following annealing at 140°C--150°C for 40 +/- 2min. Identical contact structures on chemical vapor cleaned surfaces performed consistently with no degradation following operation within the same ranges of temperature and time. The formation of Au:Ga (90:10) and Au:Ni (90:10) solid solutions was indicated by the results of X-ray diffraction (o-2theta) studies for Ni/Au contacts on HCl-treated surfaces following a 450°C anneal. Similar studies showed no evidence of interfacial reactions between similarly annealed contacts and chemical vapor cleaned GaN surfaces. Pd/Au contact structures on chemical vapor cleaned surfaces demonstrated excellent high-temperature microstructural stability as evidenced by the absence of significant change in the surface roughness, which was measured to be 6.9 +/- 0.4 nm after successive annealing through 700°C. Identical contact structures on HCl-treated surfaces exhibited poor high temperature microstructural stability, as indicated by a significant increase in the surface roughness to 11.8 +/- 0.5 nm and 80.2 +/- 0.5 nm following successive anneals at 600 and 700°C, respectively.

  17. Making Contact. Generating Interethnic Contact for Multicultural Integration and Tolerance in Amsterdam

    ERIC Educational Resources Information Center

    Muller, Floris

    2012-01-01

    Interethnic contact is considered a potent tool for the generation of interethnic understanding and tolerance. This faith has engendered countless social projects that seek to stimulate contact between members of different ethnic groups under "optimal conditions". However, the academic literature does not stipulate how, if at all, these optimal…

  18. Voltammetric studies on the potent carcinogen, 7,12-dimethylbenz[a]anthracene: Adsorptive stripping voltammetric determination in bulk aqueous forms and human urine samples and detection of DNA interaction on pencil graphite electrode.

    PubMed

    Yardim, Y; Keskin, E; Levent, A; Ozsöz, M; Sentürk, Z

    2010-01-15

    7,12-Dimethylbenz[a]anthracene (DMBA), is a widely studied polycyclic aromatic hydrocarbon that has long been recognized as a very potent carcinogen. Initially, the electrochemical oxidation of DMBA at the glassy carbon and pencil graphite electrodes in non-aqueous media (dimethylsulphoxide with lithium perchlorate) was studied by cyclic voltammetry. DMBA was irreversibly oxidized in two steps at high positive potentials, resulting in the ill-resolved formation of a couple with a reduction and re-oxidation wave at much lower potentials. Special attention was given to the use of adsorptive stripping voltammetry together with a medium exchange procedure on disposable pencil graphite electrode in aqueous solutions over the pH range of 3.0-9.0. The response was characterized with respect to pH of the supporting electrolyte, pre-concentration time and accumulation potential. Using square-wave stripping mode, the compound yielded a well-defined voltammetric response in acetate buffer, pH 4.8 at +1.15V (vs. Ag/AgCl) (a pre-concentration step being carried out at a fixed potential of +0.60V for 360s). The process could be used to determine DMBA concentrations in the range 2-10nM, with an extremely low detection limit of 0.194nM (49.7ngL(-1)). The applicability to assay of spiked human urine samples was also illustrated. Finally, the interaction of DMBA with fish sperm double-stranded DNA based on decreasing of the oxidation signal of adenine base was studied electrochemically by using differential pulse voltammetry with a pencil graphite electrode at the surface and also in solution. The favorable signal-to-noise characteristics of biosensor resulted in low detection limit (ca. 46nM) following a 300-s interaction. These results displayed that the electrochemical DNA-based biosensor could be used for the sensitive, rapid, simple and cost effective detection of DMBA-DNA interaction. PMID:20006098

  19. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo (Inventor)

    1988-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on a normal probability chart, enables prediction of the yield of good integrated circuits from the wafer.

  20. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, U. (Inventor)

    1986-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on normal probability chart enables prediction of the yield of good integrated circuits from the wafer.

  1. Kinetics, Stability, and Thermal Contact Resistance of Nickel-Ca3Co4O9 Interfaces Formed by Spark Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Holgate, T. C.; Wu, N.; Søndergaard, M.; Iversen, B. B.; Nong, N. V.; Pryds, N.

    2013-07-01

    Incorporating oxide thermoelectric (TE) materials into TE power generation modules necessitates study of the interfaces between the oxide TE elements and the interconnect materials used to transfer current between them. In this study, interfaces between pure nickel and undoped calcium cobaltate (Ca3Co4O9) have been formed directly by spark plasma sintering (SPS). An intermediate NiO phase is formed during the SPS processes, which grows during post-heating with Co entering from the cobaltate side to form a graded Ni1- x Co x O interfacial layer. The electrical and thermal transport across these interfaces, as well as the long-term chemical stability of the intermediate layers, have been studied and are discussed.

  2. High response Schottky ultraviolet photodetector formed by PEDOT:PSS transparent electrode contacts to Mg0.1Zn0.9O

    NASA Astrophysics Data System (ADS)

    Hu, Zuo-Fu; Wu, Huai-Hao; Lv, Yan-Wu; Zhang, Xi-Qing

    2015-10-01

    In this paper, we report a Schottky ultraviolet photodetector based on poly (3,4-ethylenedioxy-thiophene) poly(styrenesulfonate) (PEDOT:PSS) transparent electrode contacts to Mg0.1Zn0.9O. The I-V characteristic curves of the device are measured in the dark condition and under the illumination of a 340-nm UV light. The device shows a typical rectifying behavior with a current rectification ratio of 103 at ±2 V, which exhibits a good Schottky behavior. The photo-to-dark current ratio is high, which is 1×103 at -4 V. A peak response of 0.156 A/W at 340 nm is observed. The device also exhibits a wide response from 250 nm to 340 nm, with a response larger than 0.1 A/W. It covers the UV-B region (280 nm-320 nm), which makes the device very suitable for the detection of UV-B light. Project supported by the National Natural Science Foundation of China (Grant No. 50972007), the National Basic Research Program of China (Grant No. 2011CB932703), the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 60825407), and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics.

  3. Assessing the Relative Integrity of Formed Cardiac Linear Lesions by Recording Both Focal Monophasic Action Potentials and Contact Forces: A Technical Brief

    PubMed Central

    Benscoter, Mark A.

    2015-01-01

    The use of therapeutic ablation in patients with atrial fibrillation has become a mainstay in the treatment of this disease, yet often these individuals require multiple procedures. In other words, successful first time treatments are impacted by challenges, including the generation of linear lesions in certain anatomies like the mitral isthmus of the left atrium. Hence, there is a need to find ways to address the presence of unwanted conduction gaps at the time of lesion creation. In this paper, we describe a novel approach to examine conduction gaps, by using a proof of concept device to examine local electrical activation within the cardiac areas of an applied lesion, i.e., to locate gaps in the lesion set. To accomplish this, both epicardial and endocardial linear ablation lines composed of spot lesions with conduction gaps were created in a porcine model. The forces necessary to elicit monophasic action potentials (MAP) were collected from >200 measurements on the epicardium of the right ventricle. Ablations were then performed on the ventricular epicardium and left atrial mitral isthmus endocardially, while recording MAPs. We were able to successfully demonstrate the use of a proof of concept device to identify conduction gaps in linear lesion sets; furthermore, we were able to determine required contact forces to appropriately determine focal electrical changes of the underlying tissues. New catheter designs that incorporate capabilities to record focal MAPs could be employed clinically to better assess a given lesion quality and/or to determine the existence of an undesired conduction gap.

  4. Highly potent silver-organoalkoxysilane antimicrobial porous nanomembrane

    PubMed Central

    2013-01-01

    We used a simple electrospinning technique to fabricate a highly potent silver-organoalkoxysilane antimicrobial composite from AgNO3-polyvinylpyrrolidone (PVP)/3-aminopropyltrimethoxysilane (APTMS)/tetraethoxysilane (TEOS) solution. Spectroscopic and microscopic analyses of the composite showed that the fibers contain an organoalkoxysilane ‘skeleton,’ 0.18 molecules/nm2 surface amino groups, and highly dispersed and uniformly distributed silver nanoparticles (5 nm in size). Incorporation of organoalkoxysilanes is highly beneficial to the antimicrobial mat as (1) amino groups of APTMS are adhesive and biocidal to microorganisms, (2) polycondensation of APTMS and TEOS increases the membrane’s surface area by forming silicon bonds that stabilize fibers and form a composite mat with membranous structure and high porosity, and (3) the organoalkoxysilanes are also instrumental to the synthesis of the very small-sized and highly dispersed silver metal particles in the fiber mat. Antimicrobial property of the composite was evaluated by disk diffusion, minimum inhibition concentration (MIC), kinetic, and extended use assays on bacteria (Escherichia coli, Bacillus anthracis, Staphylococcus aureus, and Brucella suis), a fungus (Aspergillus niger), and the Newcastle disease virus. The membrane shows quick and sustained broad-spectrum antimicrobial activity. Only 0.3 mg of fibers is required to achieve MIC against all the test organisms. Bacteria are inhibited within 30 min of contact, and the fibers can be used repeatedly. The composite is silver efficient and environment friendly, and its membranous structure is suitable for many practical applications as in air filters, antimicrobial linen, coatings, bioadhesives, and biofilms. PMID:23574791

  5. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David; Cousins, Peter

    2012-12-04

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  6. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2014-07-22

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

  7. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2015-07-21

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  8. Phosphoinositides in membrane contact sites.

    PubMed

    Raiborg, Camilla; Wenzel, Eva M; Pedersen, Nina M; Stenmark, Harald

    2016-04-15

    Cellular membranes communicate extensively via contact sites that form between two membranes. Such sites allow exchange of specific ions, lipids or proteins between two compartments without content mixing, thereby preserving organellar architecture during the transfer process. Even though the molecular compositions of membrane contact sites are diverse, it is striking that several of these sites, including contact sites between the endoplasmic reticulum (ER) and endosomes, Golgi and the plasma membrane (PM), and contact sites between lysosomes and peroxisomes, contain phosphorylated derivatives of phosphatidylinositol known as phosphoinositides. In this mini-review we discuss the involvement and functions of phosphoinositides in membrane contact sites. PMID:27068950

  9. Compact contacting device

    NASA Technical Reports Server (NTRS)

    Acharya, Arun (Inventor); Gottzmann, Christian F. (Inventor); Lockett, Michael J. (Inventor); Schneider, James S. (Inventor); Victor, Richard A. (Inventor); Zawierucha, Robert (Inventor)

    1994-01-01

    An apparatus comprising a rotatable mass of structured packing for mass or heat transfer between two contacting fluids of different densities wherein the packing mass is made up of corrugated sheets of involute shape relative to the axis of the packing mass and form a logarithmic spiral curved counter to the direction of rotation.

  10. DIMETHYLARSINE AND TRIMETHYLARSINE ARE POTENT GENOTOXINS IN VITRO.

    EPA Science Inventory

    Dimethylarsine and Trimethylarsine are potent genotoxins in vitro
    Andrewes, P; Kitchin, KT; and Wallace, KA

    Abstract
    The mechanism of arsenic carcinogenesis is unclear. A complicating factor receiving increasing attention is that arsenic is biomethylated to form vari...

  11. Celebrity Patients, VIPs, and Potentates

    PubMed Central

    Groves, James E.; Dunderdale, Barbara A.; Stern, Theodore A.

    2002-01-01

    Background: During the second half of the 20th century, the literature on the doctor-patient relationship mainly dealt with the management of “difficult” (personality-disordered) patients. Similar problems, however, surround other types of “special” patients. Method: An overview and analysis of the literature were conducted. As a result, such patients can be subcategorized by their main presentations; each requires a specific management strategy. Results: Three types of “special” patients stir up irrational feelings in their caregivers. Sick celebrities threaten to focus public scrutiny on the private world of medical caregivers. VIPs generate awe in caregivers, with loss of the objectivity essential to the practice of scientific medicine. Potentates unearth narcissism in the caregiver-patient relationship, which triggers a struggle between power and shame. Pride, privacy, and the staff's need to be in control are all threatened by introduction of the special patient into medicine's closed culture. Conclusion: The privacy that is owed to sick celebrities should be extended to protect overexposed staff. The awe and loss of medical objectivity that VIPs generate are counteracted by team leadership dedicated to avoiding any deviation from standard clinical procedure. Moreover, the collective ill will surrounding potentates can be neutralized by reassuring them that they are “special”—and by caregivers mending their own vulnerable self-esteem. PMID:15014712

  12. JKR adhesion in cylindrical contacts

    NASA Astrophysics Data System (ADS)

    Sundaram, Narayan; Farris, T. N.; Chandrasekar, S.

    2012-01-01

    Planar JKR adhesive solutions use the half-plane assumption and do not permit calculation of indenter approach or visualization of adhesive force-displacement curves unless the contact is periodic. By considering a conforming cylindrical contact and using an arc crack analogy, we obtain closed-form indenter approach and load-contact size relations for a planar adhesive problem. The contact pressure distribution is also obtained in closed-form. The solutions reduce to known cases in both the adhesion-free and small-contact solution ( Barquins, 1988) limits. The cylindrical system shows two distinct regimes of adhesive behavior; in particular, contact sizes exceeding the critical (maximum) size seen in adhesionless contacts are possible. The effects of contact confinement on adhesive behavior are investigated. Some special cases are considered, including contact with an initial neat-fit and the detachment of a rubbery cylinder from a rigid cradle. A comparison of the cylindrical solution with the half-plane adhesive solution is carried out, and it indicates that the latter typically underestimates the adherence force. The cylindrical adhesive system is novel in that it possesses stable contact states that may not be attained even on applying an infinite load in the absence of adhesion.

  13. Types of Contact Lenses

    MedlinePlus

    ... Consumer Devices Consumer Products Contact Lenses Types of Contact Lenses Share Tweet Linkedin Pin it More sharing ... Orthokeratology (Ortho-K) Decorative (Plano) Contact Lenses Soft Contact Lenses Soft contact lenses are made of soft, ...

  14. Prioritized Contact Transport Stream

    NASA Technical Reports Server (NTRS)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  15. Chain Of Test Contacts For Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo

    1989-01-01

    Test structure forms chain of "cross" contacts fabricated together with large-scale integrated circuits. If necessary, number of such chains incorporated at suitable locations in integrated-circuit wafer for determination of fabrication yield of contacts. In new structure, resistances of individual contacts determined: In addition to making it possible to identify local defects, enables generation of statistical distributions of contact resistances for prediction of "parametric" contact yield of fabrication process.

  16. Crystallographic characterization of the first reported crystalline form of the potent hallucinogen (R)-2-amino-1-(8-bromobenzo[1,2-b;5,4-b']difuran-4-yl)propane or 'bromodragonfly': the 1:1 anhydrous proton-transfer compound with 3,5-dinitrosalicylic acid.

    PubMed

    Smith, Graham; Cotton, Marcus S; Wermuth, Urs D; Boyd, Sue E

    2010-05-01

    The 1:1 proton-transfer compound of the potent substituted amphetamine hallucinogen (R)-2-amino-1-(8-bromobenzo[1,2-b;5,4-b']difuran-4-yl)propane (common trivial name 'bromodragonfly') with 3,5-dinitrosalicylic acid, namely 1-(8-bromobenzo[1,2-b;5,4-b']difuran-4-yl)propan-2-aminium 2-carboxy-4,6-dinitrophenolate, C(13)H(13)BrNO(2)(+).C(7)H(3)N(2)O(7)(-), forms hydrogen-bonded cation-anion chain substructures comprising undulating head-to-tail anion chains formed through C(8) carboxyl-nitro O-H...O associations and incorporating the aminium groups of the cations. The intrachain cation-anion hydrogen-bonding associations feature proximal cyclic R(3)(3)(8) interactions involving both an N(+)-H...O(phenolate) and the carboxyl-nitro O-H...O associations and aromatic pi-pi ring interactions [minimum ring centroid separation = 3.566 (2) A]. A lateral hydrogen-bonding interaction between the third aminium H atom and a carboxyl O-atom acceptor links the chain substructures, giving a two-dimensional sheet structure. This determination represents the first of any form of this compound and is in the (R) absolute configuration. The atypical crystal stability is attributed both to the hydrogen-bonded chain substructures provided by the anions, which accommodate the aminium proton-donor groups of the cations and give crosslinking, and to the presence of the cation-anion aromatic ring pi-pi interactions. PMID:20442509

  17. Contact dermatitis in children

    PubMed Central

    2010-01-01

    Contact dermatitis in pediatric population is a common but (previously) under recognized disease. It is usually divided into the allergic and the irritant forms. The diagnosis is usually obtained with the patch test technique after conducting a thorough medical history and careful physical examination but patch testing in infants may be particularly difficult, and false-positive reactions may occur. This study also provides an overview of the most common allergens in pediatric population and discusses various therapeutic modalities. PMID:20205907

  18. Contact Hypersensitivity.

    PubMed

    Gaspari, Anthony A; Katz, Stephen I; Martin, Stefan F

    2016-01-01

    Contact hypersensitivity (CHS) is a simple in vivo assay of cell-mediated immune function in which exposure of epidermal and dermal cells to exogenous haptens results in a delayed-type hypersensitivity (DTH) reaction that can be measured and quantified. Epidermal Langerhans cells and dermal dendritic cells are the critical antigen-presenting cells in this reaction which initiate sensitization to haptens by presenting antigens to CD4- and CD8-bearing T lymphocytes which, in turn, secrete cytokines and recruit other cells to the site of the reaction. In the protocol described here, mice are shaved and the skin of their abdomens is exposed to a hapten. After 5 or 6 days (the afferent phase), the baseline ear thickness is measured prior to initiation of the efferent phase. Finally, the ear is treated epicutaneously with the hapten solution and ear thickness is measured in ∼24 hr. The magnitude of the ear swelling reaction after allergen treatment reflects the strength of the immune response. © 2016 by John Wiley & Sons, Inc. PMID:27038464

  19. EDITORIAL: Close contact Close contact

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2010-07-01

    The development of scanning probe techniques, such as scanning tunnelling microscopy [1], has often been touted as the catalyst for the surge in activity and progress in nanoscale science and technology. Images of nanoscale structural detail have served as an invaluable investigative resource and continue to fascinate with the fantastical reality of an intricate nether world existing all around us, but hidden from view of the naked eye by a disparity in scale. As is so often the case, the invention of the scanning tunnelling microscope heralded far more than just a useful new apparatus, it demonstrated the scope for exploiting the subtleties of electronic contact. The shrinking of electronic devices has been a driving force for research into molecular electronics, in which an understanding of the nature of electronic contact at junctions is crucial. In response, the number of experimental techniques in molecular electronics has increased rapidly in recent years. Scanning tunnelling microscopes have been used to study electron transfer through molecular films on a conducting substrate, and the need to monitor the contact force of scanning tunnelling electrodes led to the use of atomic force microscopy probes coated in a conducting layer as studied by Cui and colleagues in Arizona [2]. In this issue a collaboration of researchers at Delft University and Leiden University in the Netherlands report a new device architecture for the independent mechanical and electrostatic tuning of nanoscale charge transport, which will enable thorough studies of molecular transport in the future [3]. Scanning probes can also be used to pattern surfaces, such as through spatially-localized Suzuki and Heck reactions in chemical scanning probe lithography. Mechanistic aspects of spatially confined Suzuki and Heck chemistry are also reported in this issue by researchers in Oxford [4]. All these developments in molecular electronics fabrication and characterization provide alternative means to produce nanoscale device elements, such as carbon nanotube transistors [5] and high-density memory crossbar circuits [6]. Recently, the use of scanning tunnelling microscopes has broached a new field of research, which is currently attracting enormous interest—single molecule detection. In issue 25 of Nanotechnology researchers in Houston reported unprecedented sensitivities using localized surface plasmon resonance shifts of gold bipyramids to detect concentrations of substances down to the single molecule level [7]. In issue 26 a collaboration of researchers from the US and Czech Republic describe a different approach, namely tunnelling recognition. In their topical review they describe hydrogen-bond mediated tunnelling and the associated experimental methods that facilitate the detection of single molecules in a tunnel junction using chemically functionalized electrodes [8]. The nanoworld depicted by scanning probe microgaphs over 20 years ago may have looked as extraterrestrial as any science fiction generated alien terrain, but though study and analysis these nano-landscapes have become significantly less alien territory. The work so far to unveil the intricacies of electronic contact has been a story of progress in investigating this new territory and manipulating the mechanisms that govern it to formulate new devices and delve deeper into phenomena at the nanoscale. References [1] Binning G, Rohrer H, Gerber Ch and Weibel E 1982 Phys. Rev. Lett. 49 57-61 [2] X D Cui, X Zarate, J Tomfohr, O F Sankey, A Primak, A L Moore, T A Moore, D Gust, G~Harris and S M Lindsay 2002 Nanotechnology 13 5-14 [3] Martin C A, van Ruitenbeek J M and van der Zant S J H 2010 Nanotechnology 21 265201 [4] Davis J J and Hanyu Y 2010 Nanotechnology 21 265302 [5] Tans S J, Verschueren A R M and Dekker C 1998 Nature 393 49-52 [6] Chen Y, Jung G-Y, Ohlberg D A A, Li X, Stewart D R, Jeppesen J O, Nielsen K A, Stoddart J F and Williams R S 2003 Nanotechnology 14 462-8 [7] Mayer K M, Hao F, Lee S, Nordlander P and Hafner J H 2010 Nanotechnology 21 255503 [8] Lindsay S, He J, Sankey O, Hapala P, Jelinek P, Zhang P, Chang S and Huang S 2010 Nanotechnology 21 262001

  20. Formation Of Ohmic Gold Contacts On Epitaxial GaAs

    NASA Technical Reports Server (NTRS)

    Hecht, Michael H.; Bell, L. Doug; Kaiser, William J.

    1991-01-01

    New low-temperature procedure used to deposit ohmic gold contacts on gallium arsenide epitaxial films, forming ohmic electrical contacts. Keeping wafer in vacuum until metallization prevents formation of rectifying contacts.

  1. A Potent Peptidomimetic Inhibitor of Botulinum Neurotoxin Serotype a Has a Very Different Conformation Than SNAP-25 Substrate

    SciTech Connect

    Zuniga, J.E.; Schmidt, J.J.; Fenn, T.; Burnett, J.C.; Arac, D.; Gussio, R.; Stafford, R.G.; Badie, S.S.; Bavari, S.; Brunger, A.T.

    2009-05-28

    Botulinum neurotoxin serotype A is the most lethal of all known toxins. Here, we report the crystal structure, along with SAR data, of the zinc metalloprotease domain of BoNT/A bound to a potent peptidomimetic inhibitor (Ki = 41 nM) that resembles the local sequence of the SNAP-25 substrate. Surprisingly, the inhibitor adopts a helical conformation around the cleavage site, in contrast to the extended conformation of the native substrate. The backbone of the inhibitor's P1 residue displaces the putative catalytic water molecule and concomitantly interacts with the 'proton shuttle' E224. This mechanism of inhibition is aided by residue contacts in the conserved S1' pocket of the substrate binding cleft, and the induction of new hydrophobic pockets, which are not present in the apo form, especially for the P2' residue of the inhibitor. Our inhibitor is specific for BoNT/A as it does not inhibit other BoNT serotypes or thermolysin.

  2. Contact lens management of keratoconus.

    PubMed

    Downie, Laura E; Lindsay, Richard G

    2015-07-01

    Contact lenses are the primary form of visual correction for patients with keratoconus. Contemporary advances in contact lens designs and materials have significantly expanded the available fitting options for patients with corneal ectasia. Furthermore, imaging technology, such as corneal topography and anterior segment optical coherence tomography, can be applied to both gain insight into corneal microstructural changes and to guide contact lens fitting. This paper provides a comprehensive review of the range of contact lens modalities, including soft lenses, hybrid designs, rigid lenses, piggyback configurations, corneo-scleral, mini-scleral and scleral lenses that are currently available for the optical management of keratoconus. The review also discusses the importance of monitoring for disease progression in patients with keratoconus, in particular children, who tend to undergo more rapid progressive changes, so as to facilitate appropriate modification to contact lens fitting and/or potential referral for corneal collagen cross-linking treatment, as appropriate. PMID:26104589

  3. Sinterless Formation Of Contacts On Indium Phosphide

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1995-01-01

    Improved technique makes it possible to form low-resistivity {nearly equal to 10(Sup-6) ohm cm(Sup2)} electrical contacts on indium phosphide semiconductor devices without damaging devices. Layer of AgP2 40 Angstrom thick deposited on InP before depositing metal contact. AgP2 interlayer sharply reduces contact resistance, without need for sintering.

  4. Ion Implanted Passivated Contacts for Interdigitated Back Contacted Solar Cells

    SciTech Connect

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; Reedy, Robert; Bateman, Nicholas; Stradins, Pauls

    2015-06-14

    We describe work towards an interdigitated back contacted (IBC) solar cell utilizing ion implanted, passivated contacts. Formation of electron and hole passivated contacts to n-type CZ wafers using tunneling SiO2 and ion implanted amorphous silicon (a-Si) are described. P and B were ion implanted into intrinsic amorphous Si films at several doses and energies. A series of post-implant anneals showed that the passivation quality improved with increasing annealing temperatures up to 900 degrees C. The recombination parameter, Jo, as measured by a Sinton lifetime tester, was Jo ~ 14 fA/cm2 for Si:P, and Jo ~ 56 fA/cm2 for Si:B contacts. The contact resistivity for the passivated contacts, as measured by TLM patterns, was 14 milliohm-cm2 for the n-type contact and 0.6 milliohm-cm2 for the p-type contact. These Jo and pcontact values are encouraging for forming IBC cells using ion implantation to spatially define dopants.

  5. Hierarchical multicolor nano-pixel matrices formed by coordinating luminescent metal ions to a conjugated poly(4‧-octyl-2‧,6‧-bispyrazoyl pyridine) film via contact printing

    NASA Astrophysics Data System (ADS)

    Basak, Supratim; Mohiddon, Md Ahamad; Baumgarten, Martin; Müllen, Klaus; Chandrasekar, Rajadurai

    2015-02-01

    We introduce a cost-effective, yet feasible reactive printing approach namely, ``coordination chemistry at the conjugated ligand polymer surface''. By using a contact printing technique we selectively fabricated high resolution nano-pixel configurations consisting of red, blue and green (R,G,B) colors arranged in a hierarchical three-dimensional fashion. For this, we have synthesized a novel blue emitting conjugated ligand polymer, [poly(4'-octyl-2',6'-bispyrazoyl pyridine)] ( ~ 7-8 KDa) having a tridentate ligand in its repeating unit which forms a thin film prone of binding metal ions. On top of this ligand polymer film, a layer of high-resolution cross-stripes (width ca. 800 nm) was printed comprised of Eu and Tb ions over a large area ~ 100 × 100 μm2. The final woodpile-like assembly produced a new pixel group consisting of B; BG; BR; and BGR (White) colors. The area of the white emitting square is ca. 0.64 μm2. The patterned layers that make up the pixels are very thin and thus this new technique might find applications in flexible light emitting devices.

  6. Hierarchical multicolor nano-pixel matrices formed by coordinating luminescent metal ions to a conjugated poly(4′-octyl-2′,6′-bispyrazoyl pyridine) film via contact printing

    PubMed Central

    Basak, Supratim; Mohiddon, Md Ahamad; Baumgarten, Martin; Müllen, Klaus; Chandrasekar, Rajadurai

    2015-01-01

    We introduce a cost-effective, yet feasible reactive printing approach namely, “coordination chemistry at the conjugated ligand polymer surface”. By using a contact printing technique we selectively fabricated high resolution nano-pixel configurations consisting of red, blue and green (R,G,B) colors arranged in a hierarchical three-dimensional fashion. For this, we have synthesized a novel blue emitting conjugated ligand polymer, [poly(4′-octyl-2′,6′-bispyrazoyl pyridine)] ( ~ 7–8 KDa) having a tridentate ligand in its repeating unit which forms a thin film prone of binding metal ions. On top of this ligand polymer film, a layer of high-resolution cross-stripes (width ca. 800 nm) was printed comprised of Eu and Tb ions over a large area ~ 100 × 100 μm2. The final woodpile-like assembly produced a new pixel group consisting of B; BG; BR; and BGR (White) colors. The area of the white emitting square is ca. 0.64 μm2. The patterned layers that make up the pixels are very thin and thus this new technique might find applications in flexible light emitting devices. PMID:25673007

  7. Occupational contact urticaria and protein contact dermatitis.

    PubMed

    Doutre, Marie-Sylvie

    2005-01-01

    Irritant dermatitis and eczema are the most prevalent occupational skin diseases. Less common are immediate contact reactions such as contact urticaria and protein contact dermatitis. Occupational contact urticaria can be subdivided into two categories, immunological and non immunological. However, some agents can induce these two types of reactions. Contact urticaria to natural rubber latex is particularly frequent among health care personnel, but contact urticaria to a wide variety of other substances occurs in many other occupations. Among those at risk are cooks, bakers, butchers, restaurant personnel, veterinarians, hairdressers, florists, gardeners, and forestry workers. Protein contact dermatitis in some of these occupations is caused principally by proteins of animal or plant origin, especially among individuals with a history of atopic dermatitis. Diagnosis requires careful interrogation, clinical examination and skin tests (open tests and prick tests with immediate lecture) to identify a particular contact allergen. PMID:16280292

  8. Occupational protein contact dermatitis.

    PubMed

    Barbaud, Annick; Poreaux, Claire; Penven, Emmanuelle; Waton, Julie

    2015-12-01

    Occupational contact dermatitis is generally caused by haptens but can also be induced by proteins causing mainly immunological contact urticaria (ICU); chronic hand eczema in the context of protein contact dermatitis (PCD). In a monocentric retrospective study, from our database, only 31 (0.41%) of patients with contact dermatitis had positive skin tests with proteins: 22 had occupational PCD, 3 had non-occupational PCD, 5 occupational ICU and 1 cook had a neutrophilic fixed food eruption (NFFE) due to fish. From these results and analysis of literature, the characteristics of PCD can be summarized as follows. It is a chronic eczematous dermatitis, possibly exacerbated by work, suggestive if associated with inflammatory perionyxix and immediate erythema with pruritis, to be investigated when the patient resumes work after a period of interruption. Prick tests with the suspected protein-containing material are essential, as patch tests have negative results. In case of multisensitisation revealed by prick tests, it is advisable to analyse IgE against recombinant allergens. A history of atopy, found in 56 to 68% of the patients, has to be checked for. Most of the cases are observed among food-handlers but PCD can also be due to non-edible plants, latex, hydrolysed proteins or animal proteins. Occupational exposure to proteins can thus lead to the development of ICU. Reflecting hypersensitivity to very low concentrations of allergens, investigating ICU therefore requires caution and prick tests should be performed with a diluted form of the causative protein-containing product. Causes are food, especially fruit peel, non-edible plants, cosmetic products, latex, animals. PMID:26242922

  9. Contact Lens Solution Toxicity

    MedlinePlus

    ... rash and rashes clinical tools newsletter | contact Share | Contact Lens Solution Toxicity Information for adults A A A This image shows a reaction to contact lens solution. The prominent blood vessels and redness ...

  10. Contact Lens Care

    MedlinePlus

    ... For Consumers Consumer Information by Audience For Women Contact Lens Care Share Tweet Linkedin Pin it More ... 1088, www.fda.gov/medwatch Learn More about Contact Lens Care Other Tips on Contact Lenses Decorative ...

  11. Irritant Contact Dermatitis

    MedlinePlus

    ... and rashes clinical tools newsletter | contact Share | Irritant Contact Dermatitis Information for adults A A A This ... severe involvement in the patient's armpit. Overview Irritant contact dermatitis is an inflammatory rash caused by direct ...

  12. Contact Lens Risks

    MedlinePlus

    ... Health and Consumer Devices Consumer Products Contact Lenses Contact Lens Risks Share Tweet Linkedin Pin it More ... redness blurred vision swelling pain Serious Hazards of Contact Lenses Symptoms of eye irritation can indicate a ...

  13. Solution-Assisted Optical Contacting

    NASA Technical Reports Server (NTRS)

    Shaddock, Daniel; Abramovici, Alexander

    2004-01-01

    A modified version of a conventional optical-contact procedure has been found to facilitate alignment of optical components. The optical-contact procedure (called simply optical contacting in the art) is a standard means of bonding two highly polished and cleaned glass optical components without using epoxies or other adhesives. In its unmodified form, the procedure does not involve the use of any foreign substances at all: components to be optically contacted are dry. The main disadvantage of conventional optical contacting is that it is difficult or impossible to adjust the alignment of the components once they have become bonded. In the modified version of the procedure, a drop of an alcohol-based optical cleaning solution (isopropyl alcohol or similar) is placed at the interface between two components immediately before putting the components together. The solution forms a weak bond that gradually strengthens during a time interval of the order of tens of seconds as the alcohol evaporates. While the solution is present, the components can be slid, without loss of contact, to perform fine adjustments of their relative positions. After about a minute, most of the alcohol has evaporated and the optical components are rigidly attached to each other. If necessary, more solution can be added to enable resumption or repetition of the adjustment until the components are aligned to the required precision.

  14. Structures and mechanism for the design of highly potent glucocorticoids

    PubMed Central

    He, Yuanzheng; Yi, Wei; Suino-Powell, Kelly; Zhou, X Edward; Tolbert, W David; Tang, Xiaobo; Yang, Jing; Yang, Huaiyu; Shi, Jingjing; Hou, Li; Jiang, Hualiang; Melcher, Karsten; Xu, H Eric

    2014-01-01

    The evolution of glucocorticoid drugs was driven by the demand of lowering the unwanted side effects, while keeping the beneficial anti-inflammatory effects. Potency is an important aspect of this evolution as many undesirable side effects are associated with use of high-dose glucocorticoids. The side effects can be minimized by highly potent glucocorticoids that achieve the same treatment effects at lower doses. This demand propelled the continuous development of synthetic glucocorticoids with increased potencies, but the structural basis of their potencies is poorly understood. To determine the mechanisms underlying potency, we solved the X-ray structures of the glucocorticoid receptor (GR) ligand-binding domain (LBD) bound to its endogenous ligand, cortisol, which has relatively low potency, and a highly potent synthetic glucocorticoid, mometasone furoate (MF). The cortisol-bound GR LBD revealed that the flexibility of the C1-C2 single bond in the steroid A ring is primarily responsible for the low affinity of cortisol to GR. In contrast, we demonstrate that the very high potency of MF is achieved by its C-17α furoate group completely filling the ligand-binding pocket, thus providing additional anchor contacts for high-affinity binding. A single amino acid in the ligand-binding pocket, Q642, plays a discriminating role in ligand potency between MF and cortisol. Structure-based design led to synthesis of several novel glucocorticoids with much improved potency and efficacy. Together, these results reveal key structural mechanisms of glucocorticoid potency and provide a rational basis for developing novel highly potent glucocorticoids. PMID:24763108

  15. Transition metal contacts to graphene

    NASA Astrophysics Data System (ADS)

    Politou, Maria; Asselberghs, Inge; Radu, Iuliana; Conard, Thierry; Richard, Olivier; Lee, Chang Seung; Martens, Koen; Sayan, Safak; Huyghebaert, Cedric; Tokei, Zsolt; De Gendt, Stefan; Heyns, Marc

    2015-10-01

    Achieving low resistance contacts to graphene is a common concern for graphene device performance and hybrid graphene/metal interconnects. In this work, we have used the circular Transfer Length Method (cTLM) to electrically characterize Ag, Au, Ni, Ti, and Pd as contact metals to graphene. The consistency of the obtained results was verified with the characterization of up to 72 cTLM structures per metal. Within our study, the noble metals Au, Ag and Pd, which form a weaker bond with graphene, are shown to result in lower contact resistance (Rc) values compared to the more reactive Ni and Ti. X-ray Photo Electron Spectroscopy and Transmission Electron Microscopy characterization for the latter have shown the formation of Ti and Ni carbides. Graphene/Pd contacts show a distinct intermediate behavior. The weak carbide formation signature and the low Rc values measured agree with theoretical predictions of an intermediate state of weak chemisorption of Pd on graphene.

  16. Potent social synchronization can override photic entrainment of circadian rhythms.

    PubMed

    Fuchikawa, Taro; Eban-Rothschild, Ada; Nagari, Moshe; Shemesh, Yair; Bloch, Guy

    2016-01-01

    Circadian rhythms in behaviour and physiology are important for animal health and survival. Studies with individually isolated animals in the laboratory have consistently emphasized the dominant role of light for the entrainment of circadian rhythms to relevant environmental cycles. Although in nature interactions with conspecifics are functionally significant, social signals are typically not considered important time-givers for the animal circadian clock. Our results challenge this view. By studying honeybees in an ecologically relevant context and using a massive data set, we demonstrate that social entrainment can be potent, may act without direct contact with other individuals and does not rely on gating the exposure to light. We show for the first time that social time cues stably entrain the clock, even in animals experiencing conflicting photic and social environmental cycles. These findings add to the growing appreciation for the importance of studying circadian rhythms in ecologically relevant contexts. PMID:27210069

  17. Contact Lenses for Vision Correction

    MedlinePlus

    ... Ask an Ophthalmologist Español Eye Health / Glasses & Contacts Contact Lenses Sections Contact Lenses for Vision Correction Proper ... to Know About Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Written by: Kierstan Boyd ...

  18. 3-Nitrotriazole-based piperazides as potent antitrypanosomal agents.

    PubMed

    Papadopoulou, Maria V; Bloomer, William D; Rosenzweig, Howard S; O'Shea, Ivan P; Wilkinson, Shane R; Kaiser, Marcel

    2015-10-20

    Novel linear 3-nitro-1H-1,2,4-triazole-based piperazides were synthesized and evaluated as antitrypanosomal agents. In addition, some bisarylpiperazine-ethanones which were formed as by-products were also screened for antiparasitic activity. Most 3-nitrotriazole-based derivatives were potent and selective against Trypanosoma cruzi parasites, but only one displayed these desired properties against Trypanosoma brucei rhodesiense. Moreover, two 3-nitrotriazole-based chlorophenylpiperazides were moderately and selectively active against Leishmania donovani. Although the bisarylpiperazine-ethanones were active or moderately active against T. cruzi, none of them demonstrated an acceptable selectivity. In general, 3-nitrotriazole-based piperazides were less toxic to host L6 cells than the previously evaluated 3-nitrotriazole-based piperazines and seven of 13 were 1.54- to 31.2-fold more potent antichagasic agents than the reference drug benznidazole. Selected compounds showed good ADMET characteristics. One potent in vitro antichagasic compound (3) was tested in an acute murine model and demonstrated antichagasic activity after a 10-day treatment of 15 mg/kg/day. However, neither compound 3 nor benznidazole showed a statistically significant P value compared to control due to high variability in parasite burden among the untreated animals. Working as prodrugs, 3-nitrotriazole-based piperazides were excellent substrates of trypanosomal type I nitroreductases and constitute a novel class of potentially effective and more affordable antitrypanosomal agents. PMID:26363868

  19. Immunologic contact urticaria.

    PubMed

    McFadden, John

    2014-02-01

    The wheal and flare reaction from direct contact with a chemical or protein agent is known as contact urticaria. Contact urticaria can be either nonimmunologic (no sensitization required) or immunologic (sensitization required). Immunologic contact urticaria often gives a more aggravated response and has the potential to spread from the local vicinity. Skin testing in immunologic contact urticaria gives a quicker response compared with skin testing in nonimmunologic contact urticaria. There are a wide variety of agents that can cause immunologic contact urticaria, and they can be either low-molecular-weight chemicals (haptens) or proteins. PMID:24262696

  20. Metal-nanocarbon contacts

    NASA Astrophysics Data System (ADS)

    Wilhite, Patrick; Vyas, Anshul A.; Tan, Jason; Tan, Jasper; Yamada, Toshishige; Wang, Phillip; Park, Jeongwon; Yang, Cary Y.

    2014-05-01

    To realize nanocarbons in general and carbon nanotube (CNT) in particular as on-chip interconnect materials, the contact resistance stemming from the metal-CNT interface must be well understood and minimized. Understanding the complex mechanisms at the interface can lead to effective contact resistance reduction. In this study, we compile existing published results and understanding for two metal-CNT contact geometries, sidewall or side contact and end contact, and address key performance characteristics which lead to low contact resistance. Side contacts typically result in contact resistances >1 kΩ, whereas end contacts, such as that for as-grown vertically aligned CNTs on a metal underlayer, can be substantially lower. The lower contact resistance for the latter is due largely to strong bonding between edge carbon atoms with atoms on the metal surface, while carrier transport across a side-contacted interface via tunneling is generally associated with high contact resistance. Analyses of high-resolution images of interface nanostructures for various metal-CNT structures, along with their measured electrical characteristics, provide the necessary knowledge for continuous improvements of techniques to reduce contact resistance. Such contact engineering approach is described for both side and end-contacted structures.

  1. [Systemic contact dermatitis].

    PubMed

    Nowak, Daria; Gomułka, Krzysztof; Dziemieszonek, Paulina; Panaszek, Bernard

    2016-01-01

    Systemic contact dermatitis (SCD) is a skin inflammation occurring in a patient after systemic administration of a hapten, which previously caused an allergic contact skin reaction in the same person. Most frequently, hypersensitivity reactions typical for SCD occur after absorption of haptens with food or inhalation. Haptens occur mainly in the forms of metals and compounds present in natural resins, preservatives, food thickeners, flavorings and medicines. For many years, several studies have been conducted on understanding the pathogenesis of SCD in which both delayed type hypersensitivity (type IV) and immediate type I are observed. Components of the complement system are also suspected to attend there. Helper T cells (Th) (Th1 and Th2), cytotoxic T lymphocytes (Tc), and NK cells play a crucial role in the pathogenesis of SCD. They secrete a number of pro-inflammatory cytokines. In addition, regulatory T cells (Tregs) have an important role. They control and inhibit activity of the immune system during inflammation. Tregs release suppressor cytokines and interact directly with a target cell through presentation of immunosuppressive particles at the cell surface. Diagnostic methods are generally the patch test, oral provocation test, elimination diet and lymphocyte stimulation test. There are many kinds of inflammatory skin reactions caused by systemic haptens' distribution. They are manifested in a variety of clinical phenotypes of the disease. PMID:26943310

  2. Anilinotriazoles as potent gamma secretase modulators.

    PubMed

    Velter, Adriana I; Bischoff, François P; Berthelot, Didier; De Cleyn, Michel; Oehlrich, Daniel; Jaroskova, Libuse; Macdonald, Gregor; Minne, Garrett; Pieters, Serge; Rombouts, Frederik; Van Brandt, Sven; Van Roosbroeck, Yves; Surkyn, Michel; Trabanco, Andrés A; Tresadern, Gary; Wu, Tongfei; Borghys, Herman; Mercken, Marc; Masungi, Chantal; Gijsen, Harrie

    2014-12-15

    The design and synthesis of a novel series of potent gamma secretase modulators is described. Exploration of various spacer groups between the triazole ring and the aromatic appendix in 2 has led to anilinotriazole 28, which combined high in vitro and in vivo potency with an acceptable drug-like profile. PMID:25454273

  3. QS-21: a potent vaccine adjuvant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    QS-21 is an potent adjuvant derived from the bark of a Chilean tree, Quillaja saponaria. One of the advantages of this adjuvant is that it promotes a balanced humoral and cell-mediaed immune response and can be widely applicable to a variety of vaccines. This adjuvant has used for some veterinary va...

  4. Yttrium hole-barrier contacts for germanium semiconductor detectors

    NASA Astrophysics Data System (ADS)

    Hull, Ethan L.; Pehl, Richard H.; Lathrop, James R.; Suttle, Bruce E.

    2011-01-01

    Sputtered yttrium metal forms a thin hole-barrier contact on both p- and n-type germanium semiconductor detectors. Yttrium contacts can provide a sufficiently high hole barrier to prevent measurable contact leakage current below 120 K. Detectors having yttrium contacts produce good gamma-ray spectroscopy data.

  5. Nanoscale roughness contact in a slider-disk interface.

    PubMed

    Hua, Wei; Liu, Bo; Yu, Shengkai; Zhou, Weidong

    2009-07-15

    The nanoscale roughness contact between molecularly smooth surfaces of a slider-disk interface in a hard disk drive is analyzed, and the lubricant behavior at very high shear rate is presented. A new contact model is developed to study the nanoscale roughness contact behavior by classifying various forms of contact into slider-lubricant contact, slider-disk elastic contact and plastic contact. The contact pressure and the contact probabilities of the three types of contact are investigated. The new contact model is employed to explain and provide insight to an interesting experimental result found in a thermal protrusion slider. The protrusion budget for head surfing in the lubricant, which is the ideal state for contact recording, is also discussed. PMID:19550006

  6. Contact mechanisms and design principles for alloyed ohmic contacts to n-GaN

    NASA Astrophysics Data System (ADS)

    Mohammad, S. Noor

    2004-06-01

    Contact mechanisms and design principles of alloyed ohmic contacts to n-GaN are investigated. For the investigation, both tunnel contacts and thermionic contacts are considered. While the tunnel contacts include the Ti/Al/Ti/Au, Ti/Al/Ni/Au, Ti/Al/Pd/Au, (Ta,Ti)/Ni/Au, Ti/Al/Mo/Au, and Ti/Au/Pd/Au contacts, the thermionic contacts include the Ni/Au contacts. The proposed design principles correctly dictate the characteristics of all these contacts. At present, tunneling is believed to be the primary mechanism for low resistivity of the tunnel contacts. The present study demonstrates that both tunneling and thermionic emission are equally important for the low resistivity of these contacts. Band-gap narrowing and/or image force lowering due to heavy doping also contribute to the resistivity reduction of these contacts. An exciting feature of the present study is the observation of a very low work function intermetallic alloy formed during annealing of an appropriate combination of large work function metals. If the annealing conditions are optimized, the contacts become very robust, thermally stable, and lowly resistive with thermionic emission as the primary mechanism for electron transport. The observation is very promising and has potential to open up avenues for different types of thermionic contacts. The fundamental physics underlying the design principles are discussed. These principles are general enough to be applicable to other III-V nitrides, at the least.

  7. Hybrid emitter all back contact solar cell

    DOEpatents

    Loscutoff, Paul; Rim, Seung

    2016-04-12

    An all back contact solar cell has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. The other emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The solar cell includes contact holes that allow metal contacts to connect to corresponding emitters.

  8. Colored Contact Lens Dangers

    MedlinePlus

    ... Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Sep. 26, 2013 It ... she first put in a pair of colored contact lenses, Laura Butler of Parkersburg, W.Va., had " ...

  9. Simplified contact analysis

    NASA Technical Reports Server (NTRS)

    Brewe, D. E.; Hamrock, B. J.

    1978-01-01

    A simple and straightforward method for calculating the elastic deformation at the center of contact between two solids with different radii of curvature is proposed instead of the conventional contact deformation analysis for ball bearings, gears, and cams, which usually involves tedious iterative procedures or the use of design charts. Ellipticity of the contact is approximated from a least-squares power fit. Simplified expressions are derived which allow rapid calculation of deformation from the material properties and geometry of the contacting elements.

  10. Screen printed interdigitated back contact solar cell

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.; Mazaris, G. A.; Chai, A. T. (Inventor)

    1984-01-01

    Interdigitated back contact solar cells are made by screen printing dopant materials onto the back surface of a semiconductor substrate in a pair of interdigitated patterns. These dopant materials are then diffused into the substrate to form junctions having configurations corresponding to these patterns. Contacts having configurations which match the patterns are then applied over the junctions.

  11. A unified model for insulator selection to form ultra-low resistivity metal-insulator-semiconductor contacts to n-Si, n-Ge, and n-InGaAs

    NASA Astrophysics Data System (ADS)

    Agrawal, Ashish; Shukla, Nikhil; Ahmed, Khaled; Datta, Suman

    2012-07-01

    A comprehensive, physics-based unified model is developed for study of low resistivity metal-insulator-semiconductor (M-I-S) ohmic contact. Reduction in metal-induced gap state density and Fermi unpinning in semiconductor as a function of insulator thickness is coupled with electron transport including tunnel resistance through the metal-insulator-semiconductor (M-I-S) system to calculate specific contact resistivity at each insulator thickness for n-Si, n-Ge, and n-InGaAs. Low conduction band offset results in ˜1×10-9 Ω-cm2 contact resistivity with TiO2 insulator on n-Si, ˜7×10-9 Ω-cm2 can be achieved using TiO2 and ZnO on n-Ge, and ˜6×10-9 Ω-cm2 can be achieved with CdO insulator on n-InGaAs, which meet the sub-22nm CMOS requirements.

  12. Ohmic contacts to compound semiconductor transistors

    NASA Astrophysics Data System (ADS)

    Dormaier, Robert A., III

    This thesis addresses Ohmic contacts to InAlSb/InAs high electron mobility transistor (HEMT) heterostructures and InGaAs epilayers. Palladium-based contacts provide very low contact resistance to both materials, which helps minimize parasitic resistances in transistors. For Pd/Pt/Au and Pd/Ru/Au contacts to the HEMTs, lower contact resistances are correlated with increasing reaction between Pd (and Pt) and the semiconductor during annealing and aging at 175--200°C for 3 h or 1 week. Voids form in the Pt diffusion barrier layer when Pd/Pt/Au contacts are aged 1 week at 175°C and grow larger during aging at higher temperatures. The increase in contact resistance of Pd/Pt/Au contacts by more than a factor of 2 after a 1 week, 225°C aging cycle is discussed in light of the interfacial reactions that occur during aging. Alternatively, no reaction is observed between the Ru diffusion barrier and the semiconductor in Pd/Ru/Au contacts, which yield a contact resistance of 0.05 +/- 0.01 O mm after a 1 week, 225°C aging cycle that is comparable to the minimum value of 0.03 +/- 0.01 O mm yielded by Pd/Pt/Au contacts. Measurement artifacts associated with the transfer length method are identified and probe placements that mitigate the artifacts are used to reliably examine low specific contact resistance (rhoc) Ohmic contacts to InGaAs. Standardization of surface preparation procedures and a low relative humidity processing environment yield very low rhoc contacts to n-InGaAs. Examinations of wet etchants for oxide removal after UV/O 3 treatment demonstrate that BOE- and NH4OH-based etchants yield much lower rhoc values than HCl (5.0+/-0.6x10-9 and 5.7+/-1.4x10-9 versus 1.7+/-0.1x10 -8 O cm2). Palladium and Pt yield lower as-deposited and annealed rhoc values than Mo-, Ti-, and TiW-based contacts. Furthermore, collimated sputter-deposited contacts yield lower rho c values than electron-beam evaporated contacts. Several phenomena that may be responsible for the low rhoc values of Pd-based contacts are proposed and discussed. Ohmic contacts to p-InGaAs with a thin n-InGaAs cap are also examined: Pd/Ti multilayer contacts yield rhoc < 1x10-8 O cm2 after 2 hr at 270°C.

  13. Dimethylarsine and trimethylarsine are potent genotoxins in vitro.

    PubMed

    Andrewes, Paul; Kitchin, Kirk T; Wallace, Kathleen

    2003-08-01

    The mechanism of arsenic carcinogenesis is unclear. A complicating factor receiving increasing attention is that arsenic is biomethylated to form various metabolites. Eleven different arsenicals were studied for in vitro genotoxicity to supercoiled DNA (pBR 322 and phiX174). Five arsenicals showed various degrees of positivity-monomethylarsonous acid, dimethylarsinous acid, monomethylarsine, dimethylarsine, and trimethylarsine. Supercoiled DNA, blotted on nitrocellulose filter paper, was exposed to gaseous arsines by suspending the filter paper above aqueous reaction mixtures of sodium borohydride and an appropriate arsenical. All three methylated arsines damaged DNA; inorganic arsine did not. Arsines were generated in situ in reaction mixtures containing DNA by reaction of sodium borohydride with arsenite, monomethylarsonous acid, dimethylarsinous acid, and trimethylarsine oxide, at pH 8.0. Both dimethylarsine and trimethylarsine (generated from 200 micro M dimethylarsinous acid and trimethylarsine oxide, respectively) damaged DNA in less than 30 min. Under certain conditions, the two most potent genotoxic arsines, trimethylarsine and dimethylarsine, are about 100 times more potent than dimethylarsinous acid (the most potent genotoxic arsenical previously known). There was no evidence to suggest that anything other than the arsines caused the DNA damage. Possible models for the biological production of arsines were examined. The coenzymes, NADH and NADPH, are biological hydride donors. When NADH or NADPH (5 mM) were incubated with dimethylarsinous acid (0-2 mM) for 2 h, DNA damage was increased by at least 10-fold. A possible explanation for this result is that these compounds react with dimethylarsinous acid to generate dimethylarsine. DNA was incubated with a dithiol compound, dithioerythritol (5 mM), and trimethylarsine oxide (0.5 mM) for 2 h, and the reduction of trimethylarsine oxide to trimethylarsine resulted in DNA damage. PMID:12924927

  14. Mixed formulation for frictionless contact problems

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Kim, Kyun O.

    1989-01-01

    Simple mixed finite element models and a computational precedure are presented for the solution of frictionless contact problems. The analytical formulation is based on a form of Reissner's large rotation theory of the structure with the effects of transverse shear deformation included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the internal forces (stress resultants), the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The element characteristic array are obtained by using a modified form of the two-field Hellinger-Reissner mixed variational principle. The internal forces and the Lagrange multipliers are allowed to be discontinuous at interelement boundaries. The Newton-Raphson iterative scheme is used for the solution of the nonlinear algebraic equations, and the determination of the contact area and the contact pressures.

  15. Non-contact measurement of contact wire

    NASA Astrophysics Data System (ADS)

    Yi, Yaxing; Ye, Xuemei; Li, Zhongke; Yue, Kaiduan

    2008-12-01

    The overhead contact system is the power supply unit of the electric locomotive. This article is to introduce our newly developed method to measure the height and pull out value of the contact wire. A carema dolly which can move on railway is applied to bear the weight of the measure equipment; two linear CCD cameras are installed on the dolly symmetrically about the midline of two rails. While the dolly move along the railway, two CCD cameras grasp the image synchronously, and a computer real-time process the images, the height and pull out value can be calculate out from the images.

  16. A mutant with aberrant extracellular LcrV-YscF interactions fails to form pores and translocate Yop effector proteins but retains the ability to trigger Yop secretion in response to host cell contact.

    PubMed

    Harmon, Dana E; Murphy, Julia L; Davis, Alison J; Mecsas, Joan

    2013-05-01

    The plasmid-encoded type three secretion system (TTSS) of Yersinia spp. is responsible for the delivery of effector proteins into cells of the innate immune system, where these effectors disrupt the target cells' activity. Successful translocation of effectors into mammalian cells requires Yersinia to both insert a translocon into the host cell membrane and sense contact with host cells. To probe the events necessary for translocation, we investigated protein-protein interactions among TTSS components of the needle-translocon complex using a chemical cross-linking-based approach. We detected extracellular protein complexes containing YscF, LcrV, and YopD that were dependent upon needle formation. The formation of these complexes was evaluated in a secretion-competent but translocation-defective mutant, the YscFD28AD46A strain (expressing YscF with the mutations D28A and D46A). We found that one of the YscF and most of the LcrV and YopD cross-linked complexes were nearly absent in this mutant. Furthermore, the YscFD28AD46A strain did not support YopB insertion into mammalian membranes, supporting the idea that the LcrV tip complex is required for YopB insertion and translocon formation. However, the YscFD28AD46A strain did secrete Yops in the presence of host cells, indicating that a translocation-competent tip complex is not required to sense contact with host cells to trigger Yop secretion. In conclusion, in the absence of cross-linkable LcrV-YscF interactions, translocon insertion is abolished, but Yersinia still retains the ability to sense cell contact. PMID:23475976

  17. Potent inhibition of tau fibrillization with a multivalent ligand

    PubMed Central

    Honson, Nicolette S.; Jensen, Jordan R.; Darby, Michael V.; Kuret, Jeff

    2007-01-01

    Small-molecule inhibitors of tau fibrillization are under investigation as tools for interrogating the tau aggregation pathway and as potential therapeutic agents for Alzheimer’s disease. Established inhibitors include thiacarbocyanine dyes, which can inhibit recombinant tau fibrillization in the presence of anionic surfactant aggregation inducers. In an effort to increase inhibitory potency, a cyclic bis-thiacarbocyanine molecule containing two thiacarbocyanine moieties was synthesized and characterized with respect to tau fibrillization inhibitory activity by electron microscopy and ligand aggregation state by absorbance spectroscopy. Results showed that the inhibitory activity of the bis-thiacarbocyanine was qualitatively similar to a monomeric cyanine dye, but was more potent with 50% inhibition achieved at ~80 nM concentration. At all concentrations tested in aqueous solution, the bis-thiacarbocyanine collapsed to form a closed clamshell structure. However, the presence of tau protein selectively stabilized the open conformation. These results suggest that the inhibitory activity of bis-thiacarbocyanine results from multivalency, and reveal a route to more potent tau aggregation inhibitors. PMID:17854770

  18. Potent inhibition of tau fibrillization with a multivalent ligand

    SciTech Connect

    Honson, Nicolette S.; Jensen, Jordan R.; Darby, Michael V.; Kuret, Jeff

    2007-11-09

    Small-molecule inhibitors of tau fibrillization are under investigation as tools for interrogating the tau aggregation pathway and as potential therapeutic agents for Alzheimer's disease. Established inhibitors include thiacarbocyanine dyes, which can inhibit recombinant tau fibrillization in the presence of anionic surfactant aggregation inducers. In an effort to increase inhibitory potency, a cyclic bis-thiacarbocyanine molecule containing two thiacarbocyanine moieties was synthesized and characterized with respect to tau fibrillization inhibitory activity by electron microscopy and ligand aggregation state by absorbance spectroscopy. Results showed that the inhibitory activity of the bis-thiacarbocyanine was qualitatively similar to a monomeric cyanine dye, but was more potent with 50% inhibition achieved at {approx}80 nM concentration. At all concentrations tested in aqueous solution, the bis-thiacarbocyanine collapsed to form a closed clamshell structure. However, the presence of tau protein selectively stabilized the open conformation. These results suggest that the inhibitory activity of bis-thiacarbocyanine results from multivalency, and reveal a route to more potent tau aggregation inhibitors.

  19. Optical contact micrometer

    DOEpatents

    Jacobson, Steven D.

    2014-08-19

    Certain examples provide optical contact micrometers and methods of use. An example optical contact micrometer includes a pair of opposable lenses to receive an object and immobilize the object in a position. The example optical contact micrometer includes a pair of opposable mirrors positioned with respect to the pair of lenses to facilitate viewing of the object through the lenses. The example optical contact micrometer includes a microscope to facilitate viewing of the object through the lenses via the mirrors; and an interferometer to obtain one or more measurements of the object.

  20. Miniature intermittent contact switch

    NASA Technical Reports Server (NTRS)

    Sword, A.

    1972-01-01

    Design of electric switch for providing intermittent contact is presented. Switch consists of flexible conductor surrounding, but separated from, fixed conductor. Flexing of outside conductor to contact fixed conductor completes circuit. Advantage is small size of switch compared to standard switches.

  1. Language Contact: An Introduction.

    ERIC Educational Resources Information Center

    Thomason, Sarah G.

    This book surveys situations in which language contact arises and focuses on what happens to the languages themselves: sometimes nothing, sometimes the incorporation of new words, sometimes the spread of new sounds and sentence structures across many languages and wide swathes of territory. It outlines the origins and results of contact-induced…

  2. Superconducting quantum point contacts

    NASA Astrophysics Data System (ADS)

    Bretheau, L.; Girit, Ç.; Tosi, L.; Goffman, M.; Joyez, P.; Pothier, H.; Esteve, D.; Urbina, C.

    2012-01-01

    We review our experiments on the electronic transport properties of atomic contacts between metallic electrodes, in particular superconducting ones. Despite ignorance of the exact atomic configuration, these ultimate quantum point contacts can be manipulated and well characterized in-situ. They allow performing fundamental tests of the scattering theory of quantum transport. In particular, we discuss the case of the Josephson effect.

  3. Serendipitous oxidation product of BIBN4096BS: a potent CGRP receptor antagonist.

    PubMed

    Dasgupta, Bireshwar; Kozlowski, Edward; Schroeder, Daniel R; Torrente, John R; Xu, Cen; Pin, Sokhom; Conway, Charlie M; Dubowchik, Gene M; Macor, John E; Vrudhula, Vivekananda M

    2014-06-15

    An oxidation product (5) formed during the synthesis of BIBN-4096BS (1) was found to be a potent CGRP antagonist (IC50=0.11nM). While 5 was found to be ten-fold less potent than 1, another analog 8 with lower molecular weight containing the oxidized fragment demonstrated twenty-fold higher activity than its parent 7. Alternative conditions which preclude the formation of the oxidation product are described. The activities of 1, 5, 7 and 8 in functional cAMP assay are also discussed. PMID:24794104

  4. Carvacrol as a potent natural acaricide against Dermanyssus gallinae.

    PubMed

    Tabari, Mohaddeseh Abouhosseini; Youssefi, Mohammad Reza; Barimani, Alireza; Araghi, Atefeh

    2015-10-01

    Resistance to conventional synthetic pesticides has been widely reported in Dermanyssus gallinae in poultry production systems. Introducing novel acaricides to poultry industry today is more urgent than ever. Research in this field recently focused on plants and plant-derived compounds as acaricides. In the present study, acaricidal activity of three plant bioactive components, carvacrol, thymol, and farnesol, was assessed against D. gallinae and compared with synthetic pesticide permethrin. Mode of acaricidal action was determined by contact toxicity and fumigant toxicity bioassays. Except farnesol which did not cause any mortality, carvacrol and thymol were found to be toxic to D. gallinae with LD50 values of 1 and 3.15 μg/cm(3), respectively. Permethrin gave the LD50 value of 31.95 μg/cm(3) which was less efficient than carvacrol and thymol. In fumigant toxicity bioassay, mortality rate in carvacrol- and thymol-treated groups in closed method was significantly higher than the open one. On the other hand, permethrin exhibited poor fumigant toxicity as there was no statistically significant difference between mortality rate in open and closed methods. These findings revealed that mechanism of acaricidal activity of carvacrol and thymol but not permethrin was mainly due to fumigant action. Results of the present study suggested that carvacrol and thymol, especially carvacrol, can be developed as a novel potent bioacaricide against D. gallinae. PMID:26143865

  5. Potent antagonists of somatostatin: synthesis and biology.

    PubMed

    Hocart, S J; Jain, R; Murphy, W A; Taylor, J E; Morgan, B; Coy, D H

    1998-03-26

    The search for synthetic analogues of somatostatin (SRIF) which exhibit selective affinities for the five known receptor subtypes (sst1-5) has generated a large number of potent agonist analogues. Many of these agonists display good subtype selectivities and affinities for the subtypes 2, 3, and 5, with very few selective for sst1 or sst4. Until the recent report by Bass and co-workers (Mol. Pharmacol. 1996, 50, 709-715; erratum, Mol. Pharmacol. 1997, 51, 170), no true antagonists had been discovered, let alone any displaying differential receptor subtype selectivity. In this present study, we explore the effect of this putative L5,D6 antagonist motif on various series of somatostatin agonist analogues, both linear and cyclic. It was found that many D5,L6 agonists could be converted into competitive antagonists by applying this motif, the most potent of which was H-Nal-cyclo[DCys-Pal-DTrp-Lys-Val-Cys]-Nal-NH2 (32). This antagonist was selective for hsst2 with an affinity of 75 nM and an IC50 of 15.1 nM against SRIF-14 in a rat in vitro antagonist bioassay. Receptor-selective somatostatin antagonists should provide valuable tools for characterizing the many important physiological functions of this neuropeptide. PMID:9544214

  6. Engineered Promoters for Potent Transient Overexpression

    PubMed Central

    Ideses, Diana; Tikotzki, Ravid; Shir-Shapira, Hila; Shefi, Orit; Juven-Gershon, Tamar

    2016-01-01

    The core promoter, which is generally defined as the region to which RNA Polymerase II is recruited to initiate transcription, plays a pivotal role in the regulation of gene expression. The core promoter consists of different combinations of several short DNA sequences, termed core promoter elements or motifs, which confer specific functional properties to each promoter. Earlier studies that examined the ability to modulate gene expression levels via the core promoter, led to the design of strong synthetic core promoters, which combine different core elements into a single core promoter. Here, we designed a new core promoter, termed super core promoter 3 (SCP3), which combines four core promoter elements (the TATA box, Inr, MTE and DPE) into a single promoter that drives prolonged and potent gene expression. We analyzed the effect of core promoter architecture on the temporal dynamics of reporter gene expression by engineering EGFP expression vectors that are driven by distinct core promoters. We used live cell imaging and flow cytometric analyses in different human cell lines to demonstrate that SCPs, particularly the novel SCP3, drive unusually strong long-term EGFP expression. Importantly, this is the first demonstration of long-term expression in transiently transfected mammalian cells, indicating that engineered core promoters can provide a novel non-viral strategy for biotechnological as well as gene-therapy-related applications that require potent expression for extended time periods. PMID:26872062

  7. BISON Contact Improvements CASL FY14 Report

    SciTech Connect

    B. W. Spencer; J. D. Hales; D. R. Gaston; D. A. Karpeev; R. L. Williamson; S. R. Novascone; D. M. Perez; R. J. Gardner; K. A. Gamble

    2014-09-01

    The BISON code is the foundation for multiple fuel performance modeling efforts, and is cur- rently under heavy development. For a variety of fuel forms, the effects of heat conduction across a gap and mechanical contact between components of a fuel system are very significant. It is thus critical that BISON have robust capabilities for enforcement of thermal and mechanical contact. BISON’s solver robustness has generally been quite good before mechanical contact between the fuel and cladding occurs, but there have been significant challenges obtaining converged so- lutions once that contact occurs and the solver begins to enforce mechanical contact constraints. During the current year, significant development effort has been focused on the enforcement of mechanical contact to provide improved solution robustness. In addition to this work to improve mechanical contact robustness, an investigation into ques- tionable results attributable to thermal contact has been performed. This investigation found that the order of integration typically used on the surfaces involved in thermal contact was not suffi- ciently high. To address this problem, a new option was provided to permit the use of a different integration order for surfaces, and new usage recommendations were provided.

  8. Electrical Contacts to Nanomaterials.

    PubMed

    Bandaru, P R; Faraby, H; DiBattista, M

    2015-12-01

    The efficient passage of electrical current from an external contact to a nanomaterial is necessary for harnessing characteristics unique to the nanoscale, such as those relevant to energy quantization. However, an intrinsic resistance pertinent to dimensionality crossover and the presence of impurities precludes optimal electrical contact formation. In this review, we first discuss the relevant principles and contact resistance measurement methodologies, with modifications necessary for the nanoscale. Aspects related to the deposition of the contact material are deemed to be crucial. Consequently, the use of focused ion beam (FIB) based deposition, which relies on the ion-induced decomposition of a metallorganic precursor, and which has been frequently utilized for nanoscale contacts is considered in detail. PMID:26682353

  9. Hemin as a generic and potent protein misfolding inhibitor.

    PubMed

    Liu, Yanqin; Carver, John A; Ho, Lam H; Elias, Abigail K; Musgrave, Ian F; Pukala, Tara L

    2014-11-14

    Protein misfolding causes serious biological malfunction, resulting in diseases including Alzheimer's disease, Parkinson's disease and cataract. Molecules which inhibit protein misfolding are a promising avenue to explore as therapeutics for the treatment of these diseases. In the present study, thioflavin T fluorescence and transmission electron microscopy experiments demonstrated that hemin prevents amyloid fibril formation of kappa-casein, amyloid beta peptide and α-synuclein by blocking β-sheet structure assembly which is essential in fibril aggregation. Further, inhibition of fibril formation by hemin significantly reduces the cytotoxicity caused by fibrillar amyloid beta peptide in vitro. Interestingly, hemin degrades partially formed amyloid fibrils and prevents further aggregation to mature fibrils. Light scattering assay results revealed that hemin also prevents protein amorphous aggregation of alcohol dehydrogenase, catalase and γs-crystallin. In summary, hemin is a potent agent which generically stabilises proteins against aggregation, and has potential as a key molecule for the development of therapeutics for protein misfolding diseases. PMID:25450392

  10. Telescopic vision contact lens

    NASA Astrophysics Data System (ADS)

    Tremblay, Eric J.; Beer, R. Dirk; Arianpour, Ashkan; Ford, Joseph E.

    2011-03-01

    We present the concept, optical design, and first proof of principle experimental results for a telescopic contact lens intended to become a visual aid for age-related macular degeneration (AMD), providing magnification to the user without surgery or external head-mounted optics. Our contact lens optical system can provide a combination of telescopic and non-magnified vision through two independent optical paths through the contact lens. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8x - 3x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision.

  11. Optical contacting of quartz

    NASA Technical Reports Server (NTRS)

    Payne, L. L.

    1982-01-01

    The strength of the bond between optically contacted quartz surfaces was investigated. The Gravity Probe-B (GP-B) experiment to test the theories of general relativity requires extremely precise measurements. The quartz components of the instruments to make these measurements must be held together in a very stable unit. Optical contacting is suggested as a possible method of joining these components. The fundamental forces involved in optical contacting are reviewed and relates calculations of these forces to the results obtained in experiments.

  12. Making End-Bonded Contacts to Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Tang, Jianshi; Cao, Qing; Tulevski, George; Han, Shu-Jen

    As a promising candidate for post-Si era, the implementation of carbon nanotube (CNT)-based CMOS technology requires both high-quality channel and electrical contacts that can be scaled down to sub-10 nm. In the efforts of making scalable contacts to CNT, we have recently demonstrated low-resistance end-bonded carbide contacts, formed by the reaction of Mo with CNT through high-temperature annealing (>800 oC). Such end-bonded contact scheme leads to a size-independent contact resistance of about 30 kilo-ohms, which overcomes the scaling limit of conventional side contacts. In this talk, we will present another strategy to make end-bonded contacts to CNTs through thermal annealing at much lower temperatures (400-600 oC). The contact metals are carefully chosen to have a high carbon solubility, so that the carbon atoms could dissolve into the contacts to inherently form end-bonded contacts. Experimental results, including Raman, SEM, and electrical measurements, with different annealing temperatures will be presented. The length-dependent contact resistance for this new end-bonded contact will be evaluated and compared with that of conventional side contact and also end-bonded carbide contact.

  13. Conformational Changes in BAK, a Pore-forming Proapoptotic Bcl-2 Family Member, upon Membrane Insertion and Direct Evidence for the Existence of BH3-BH3 Contact Interface in BAK Homo-oligomers*

    PubMed Central

    Oh, Kyoung Joon; Singh, Pawan; Lee, Kyungro; Foss, Kelly; Lee, Shinyoub; Park, Minji; Lee, Steffi; Aluvila, Sreevidya; Park, Matthew; Singh, Puja; Kim, Ryung-Suk; Symersky, Jindrich; Walters, D. Eric

    2010-01-01

    During apoptosis, the pro-apoptotic Bcl-2 family proteins BAK and BAX form large oligomeric pores in the mitochondrial outer membrane. Apoptotic factors, including cytochrome c, are released through these pores from the mitochondrial intermembrane space into the cytoplasm where they initiate the cascade of events leading to cell death. To better understand this pivotal step toward apoptosis, a method was developed to induce membrane permeabilization by BAK in the membrane without using the full-length protein. Using a soluble form of BAK with a hexahistidine tag at the C terminus and a liposomal system containing the Ni2+-nitrilotriacetic acid lipid analog that can bind hexahistidine-tagged proteins, BAK oligomers were formed in the presence of the activator protein p7/p15Bid. In this system, we determined the conformational changes in BAK upon membrane insertion by applying the site-directed spin labeling method of EPR to 13 different amino acid locations. Upon membrane insertion, the BH3 domains were reorganized, and the ?5-?6 helical hairpin structure was partially exposed to the membrane environment. The monomer-monomer interface in the oligomeric structure was also mapped by measuring the distance-dependent spin-spin interactions for each residue location. Spin labels attached in the BH3 domain were juxtaposed within 510 ? distance in the oligomeric form in the membrane. These results are consistent with the current hypothesis that BAK or BAX forms homodimers, and these homodimers assemble into a higher order oligomeric pore. Detailed analyses of the data provide new insights into the structure of the BAX or BAK homodimer. PMID:20605789

  14. Potent antitrypanosomal triterpenoid saponins from Mussaenda luteola.

    PubMed

    Mohamed, Shaymaa M; Bachkeet, Enaam Y; Bayoumi, Soad A; Jain, Surendra; Cutler, Stephen J; Tekwani, Babu L; Ross, Samir A

    2015-12-01

    Five new triterpenoid saponins, heinsiagenin A 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (1), heinsiagenin A 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (2), 2α-hydroxyheinsiagenin A 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (3), 2α-hydroxyheinsiagenin A 3-O-[β-d-glucopyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (4) and N-(2S, 3R, 4R-3-methyl-4-pentanolid-2-yl)-18-hydroxylanosta-8 (9), 22E, 24E-trien-27-amide-3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (5) were isolated from the aerial parts of Mussaenda luteola Delile (Rubiaceae). Structural elucidation was based on the analysis of spectroscopic data (1D and 2D NMR) and HR-ESI-MS. Compound 1 showed potent antitrypanosomal activity with an IC50 value of 8.80μM. Compounds 2-4 showed highly potent antitrypanosomal activity with IC50 values ranging between (2.57-2.84μM) and IC90 values ranging between (3.36-4.35μM), which are 5 fold greater than the positive control DFMO (IC50 and IC90 values of 13.06 and 28.99μM, respectively). Compounds 1 and 2 showed moderate affinity to μ-opioid receptors with Ki values of 9.936μM and 0.872μM, respectively compared to a Ki value of 1.958nM for the positive control, naloxone HCl. PMID:26524249

  15. Occupational Contact Dermatitis

    PubMed Central

    2008-01-01

    Occupational contact dermatitis accounts for 90% of all cases of work-related cutaneous disorders. It can be divided into irritant contact dermatitis, which occurs in 80% of cases, and allergic contact dermatitis. In most cases, both types will present as eczematous lesions on exposed parts of the body, notably the hands. Accurate diagnosis relies on meticulous history taking, thorough physical examination, careful reading of Material Safety Data Sheets to distinguish between irritants and allergens, and comprehensive patch testing to confirm or rule out allergic sensitization. This article reviews the pathogenesis and clinical manifestations of occupational contact dermatitis and provides diagnostic guidelines and a rational approach to management of these often frustrating cases. PMID:20525126

  16. Hemin as a generic and potent protein misfolding inhibitor

    SciTech Connect

    Liu, Yanqin; Carver, John A.; Ho, Lam H.; Elias, Abigail K.; Musgrave, Ian F.; Pukala, Tara L.

    2014-11-14

    Highlights: • Hemin prevents Aβ42, α-synuclein and RCM-κ-casein forming amyloid fibrils. • Hemin inhibits the β-sheet structure formation of Aβ42. • Hemin reduces the cell toxicity caused by fibrillar Aβ42. • Hemin dissociates partially formed Aβ42 fibrils. • Hemin prevents amorphous aggregation by ADH, catalase and γs-crystallin. - Abstract: Protein misfolding causes serious biological malfunction, resulting in diseases including Alzheimer’s disease, Parkinson’s disease and cataract. Molecules which inhibit protein misfolding are a promising avenue to explore as therapeutics for the treatment of these diseases. In the present study, thioflavin T fluorescence and transmission electron microscopy experiments demonstrated that hemin prevents amyloid fibril formation of kappa-casein, amyloid beta peptide and α-synuclein by blocking β-sheet structure assembly which is essential in fibril aggregation. Further, inhibition of fibril formation by hemin significantly reduces the cytotoxicity caused by fibrillar amyloid beta peptide in vitro. Interestingly, hemin degrades partially formed amyloid fibrils and prevents further aggregation to mature fibrils. Light scattering assay results revealed that hemin also prevents protein amorphous aggregation of alcohol dehydrogenase, catalase and γs-crystallin. In summary, hemin is a potent agent which generically stabilises proteins against aggregation, and has potential as a key molecule for the development of therapeutics for protein misfolding diseases.

  17. ELECTRIC CONTACT MEANS

    DOEpatents

    Grear, J.W. Jr.

    1959-03-10

    A switch adapted to maintain electrical connections under conditions of vibration or acceleration is described. According to the invention, thc switch includes a rotatable arm carrying a conductive bar arranged to close against two contacts spaced in the same plane. The firm and continuous engagement of the conductive bar with the contacts is acheived by utilizeing a spring located betwenn the vbar and athe a rem frzme and slidable mounting the bar in channel between two arms suspendef from the arm frame.

  18. The impact of contact

    NASA Astrophysics Data System (ADS)

    Finney, B.

    1986-10-01

    Scenarios of the impact on human society of radio contact with an extraterrestrial civilization are presented. Some believe that contact with advanced extraterrestrials would quickly devastate the human spirit, while others believe that these super-intelligent beings would show the inhabitants of the earth how to live in peace. It is proposed that the possible existence of extraterrestrial civilizations and the development of means of studying and communicating with them need to be considered.

  19. A potent peptidomimetic inhibitor of botulinum neurotoxin serotype A has a very different conformation than SNAP-25 substrate

    PubMed Central

    Zuniga, Jorge E.; Schmidt, James J.; Fenn, Timothy; Burnett, James C.; Ara, Demet; Gussio, Rick; Stafford, Robert G.; Badie, Shirin S.; Bavari, Sina; Brunger, Axel T.

    2008-01-01

    Botulinum neurotoxin serotype A is the most lethal of all known toxins. Here, we report the crystal structure, along with SAR data, of the zinc metalloprotease domain of BoNT/A bound to a potent peptidomimetic inhibitor (Ki = 41 nM) that resembles the local sequence of the SNAP-25 substrate. Surprisingly, the inhibitor adopts a helical conformation around the cleavage site, in contrast to the extended conformation of the native substrate. The backbone of the inhibitors P1 residue displaces the putative catalytic water molecule and concomitantly interacts with the proton shuttle E224. This mechanism of inhibition is aided by residue contacts in the conserved S1? pocket of the substrate binding cleft, and the induction of new hydrophobic pockets, which are not present in the apo form, especially for the P2? residue of the inhibitor. Our inhibitor is specific for BoNT/A as it does not inhibit other BoNT serotypes or thermolysin. PMID:18940613

  20. Specific contact resistance of the porous silicon and silver metal Ohmic contact structure

    NASA Astrophysics Data System (ADS)

    Vinod, P. N.

    2005-09-01

    We report the experimental result of the specific contact resistance (ρc) of porous silicon and silver metal Ohmic contact structure formed on the n+ region (doped with phosphorous atoms) to boron-doped p-type single crystalline silicon. The contact structure consists of sintered Ag metal grid contact on a porous silicon surface, which was formed on the n+ region by an electrochemical etching process. The electrical properties of the Ohmic contact thus formed are estimated by measuring the specific contact resistance at the interface of the porous silicon/silver Ohmic contact structure as a function of surface doping concentration. The measured value of ρc as a function of the surface doping shows that ρc is a strong function of surface doping, and decreases with increasing doping. The measured data provide reliable values of ρc for the silver metal/porous silicon/p-type c-Si structure, which enable us to study the electrical properties of the porous silicon/silver Ohmic contact.

  1. Lettuce contact allergy.

    PubMed

    Paulsen, Evy; Andersen, Klaus E

    2016-02-01

    Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22%. The majority of cases are non-occupational, and may partly be caused by cross-reactivity. The sesquiterpene lactone mix seems to be a poor screening agent for lettuce contact allergy, as the prevalence of positive reactions is significantly higher in non-occupationally sensitized patients. Because of the easy degradability of lettuce allergens, it is recommended to patch test with freshly cut lettuce stem and supplement this with Compositae mix. As contact urticaria and protein contact dermatitis may present as dermatitis, it is important to perform prick-to-prick tests, and possibly scratch patch tests as well. Any person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy. PMID:26289653

  2. Mechanistic Basis for the Potent Anti-angiogenic Activity of Semaphorin 3F

    PubMed Central

    Guo, Hou-Fu; Li, Xiaobo; Parker, Matthew W.; Waltenberger, Johannes; Becker, Patrice M.; Vander Kooi, Craig W.

    2013-01-01

    Neuropilin-1 (Nrp1), an essential type I transmembrane receptor, binds two secreted ligand families, Vascular Endothelial Growth Factor (VEGF) and class III Semaphorin (Sema3). VEGF-A and Sema3F have opposing roles in regulating Nrp1 vascular function in angiogenesis. VEGF-A functions as one of the most potent pro-angiogenic cytokines while Sema3F is a uniquely potent endogenous angiogenesis inhibitor. Sema3 family members require proteolytic processing by furin to enable competitive binding to Nrp1. We demonstrate that the furin processed C-terminal domain of Sema3F (C-furSema) potently inhibits VEGF-A dependent activation of endothelial cells. We find that this potent activity is due to unique hetero-bivalent engagement of Nrp1 by two distinct sites in the Sema3F C-terminal domain. One of the sites is the C-terminal arginine, liberated by furin cleavage, and the other is a novel upstream helical motif centered on the intermolecular disulfide. Using a novel chimeric C-furSema, we demonstrate that combining a single C-terminal arginine with the helical motif is necessary and sufficient for potent inhibition of VEGF-A binding to Nrp1. We further demonstrate that the multiple furin-processed variants of Sema3A, with altered proximity of the two binding motifs, have dramatically different potencies. This suggests that furin processing not only switches Sema3 into an activated form but, depending on the site processed, can also tune potency. These data establish the basis for potent competitive Sema3 binding to Nrp1 and provide a basis for the design of bivalent Nrp inhibitors. PMID:24079887

  3. The contact caveat: negative contact predicts increased prejudice more than positive contact predicts reduced prejudice.

    PubMed

    Barlow, Fiona Kate; Paolini, Stefania; Pedersen, Anne; Hornsey, Matthew J; Radke, Helena R M; Harwood, Jake; Rubin, Mark; Sibley, Chris G

    2012-12-01

    Contact researchers have largely overlooked the potential for negative intergroup contact to increase prejudice. In Study 1, we tested the interaction between contact quantity and valence on prejudice toward Black Australians (n = 1,476), Muslim Australians (n = 173), and asylum seekers (n = 293). In all cases, the association between contact quantity and prejudice was moderated by its valence, with negative contact emerging as a stronger and more consistent predictor than positive contact. In Study 2, White Americans (n = 441) indicated how much positive and negative contact they had with Black Americans on separate measures. Although both quantity of positive and negative contact predicted racism and avoidance, negative contact was the stronger predictor. Furthermore, negative (but not positive) contact independently predicted suspicion about Barack Obama's birthplace. These results extend the contact hypothesis by issuing an important caveat: Negative contact may be more strongly associated with increased racism and discrimination than positive contact is with its reduction. PMID:22941796

  4. Focusing on Contact Lens Safety

    MedlinePlus

    ... Consumers Home For Consumers Consumer Updates Focusing on Contact Lens Safety Share Tweet Linkedin Pin it More ... substantial consumer injury. Back to top Types of Contact Lenses General categories Soft contact lenses. These are ...

  5. Glenohumeral contact forces.

    PubMed

    Anglin, C; Wyss, U P; Pichora, D R

    2000-01-01

    Glenohumeral contact forces have only been calculated previously either for simple abduction or for athletic activities. The objective of this study was to determine the glenohumeral contact forces for tasks which are demanding of the shoulder but which would commonly be performed by older people. The functional tasks chosen were using the arms to stand up from and sit down into a chair, walking with a cane, lifting a 5 kg box to shoulder height with both hands, and lifting a 10 kg suitcase. The trunk angles, arm angles and hand loads of six healthy subjects, average age 55 years, were recorded. This information was input into a biomechanical computer model which optimized the muscle force distribution by minimizing the sum of squared muscle stresses subject to constraints on the maximum muscle forces and maintaining the direction of the resultant force within the glenoid fossa. Average contact forces ranged from 1.3 to 2.4 times body weight (930-1720 N), the highest force being for lifting a suitcase. This latter value would be even higher if lifting either a greater load or to a greater height. Thus, contact forces at the shoulder should not be underestimated. This study provides functionally relevant contact forces which can be used for mechanical testing or finite element modelling of shoulder prostheses. PMID:11201411

  6. Solar cell contacts

    SciTech Connect

    Meier, D.L.; Campbell, R.B.; Davis, J.R.; Rai-Choudhury, P.; Sienkiewicz, L.J.

    1982-09-01

    Two experimental contact systems were examined and compared to a baseline contact system consisting of evaporated layers of titanium, palladium, and silver and an electroplated layer of copper. The first experimental contact system consisted of evaporated layers of titanium, nickel, and copper and an electroplated layer of copper. This system performed as well as the baseline system in all respects, including its response to temperature stress tests, to a humidity test, and to an accelerated aging test. In addition, the cost of this system is estimated to be only 43% of the cost of the baseline system at a production level of 25 MW/year. The second experimental contact system consisted of evaporated layers of nickel and copper and an electroplated layer of copper. Cells with this system show serious degradation in a temperature stress test at 350/sup 0/C for 30 minutes. Auger Electron Spectroscopy was used to show that the evaporated nickel layer is not an adequate barrier to copper diffusion even at temperatures as low as 250/sup 0/C. This fact brings into question the longterm reliability of this contact system.

  7. Intergroup contact theory.

    PubMed

    Pettigrew, T F

    1998-01-01

    Allport specified four conditions for optimal intergroup contact: equal group status within the situation, common goals, intergroup cooperation and authority support. Varied research supports the hypothesis, but four problems remain. 1. A selection bias limits cross-sectional studies, since prejudiced people avoid intergroup contact. Yet research finds that the positive effects of cross-group friendship are larger than those of the bias. 2. Writers overburden the hypothesis with facilitating, but not essential, conditions. 3. The hypothesis fails to address process. The chapter proposes four processes: learning about the outgroup, changed behavior, affective ties, and ingroup reappraisal. 4. The hypothesis does not specify how the effects generalize to other situations, the outgroup or uninvolved outgroups. Acting sequentially, three strategies enhance generalization-decategorization, salient categorization, and recategorization. Finally, both individual differences and societal norms shape intergroup contact effects. The chapter outlines a longitudinal intergroup contact theory. It distinguishes between essential and facilitating factors, and emphasizes different outcomes for different stages of contact. PMID:15012467

  8. Diagnosis and management of contact dermatitis.

    PubMed

    Usatine, Richard P; Riojas, Marcela

    2010-08-01

    Contact dermatitis is a common inflammatory skin condition characterized by erythematous and pruritic skin lesions that occur after contact with a foreign substance. There are two forms of contact dermatitis: irritant and allergic. Irritant contact dermatitis is caused by the non-immune-modulated irritation of the skin by a substance, leading to skin changes. Allergic contact dermatitis is a delayed hypersensitivity reaction in which a foreign substance comes into contact with the skin; skin changes occur after reexposure to the substance. The most common substances that cause contact dermatitis include poison ivy, nickel, and fragrances. Contact dermatitis usually leads to erythema and scaling with visible borders. Itching and discomfort may also occur. Acute cases may involve a dramatic flare with erythema, vesicles, and bullae; chronic cases may involve lichen with cracks and fissures. When a possible causative substance is known, the first step in confirming the diagnosis is determining whether the problem resolves with avoidance of the substance. Localized acute allergic contact dermatitis lesions are successfully treated with mid- or high-potency topical steroids, such as triamcinolone 0.1% or clobetasol 0.05%. If allergic contact dermatitis involves an extensive area of skin (greater than 20 percent), systemic steroid therapy is often required and offers relief within 12 to 24 hours. In patients with severe rhus dermatitis, oral prednisone should be tapered over two to three weeks because rapid discontinuation of steroids can cause rebound dermatitis. If treatment fails and the diagnosis or specific allergen remains unknown, patch testing should be performed. PMID:20672788

  9. Polyethyleneimine is a potent mucosal adjuvant for viral glycoprotein antigens.

    PubMed

    Wegmann, Frank; Gartlan, Kate H; Harandi, Ali M; Brinckmann, Sarah A; Coccia, Margherita; Hillson, William R; Kok, Wai Ling; Cole, Suzanne; Ho, Ling-Pei; Lambe, Teresa; Puthia, Manoj; Svanborg, Catharina; Scherer, Erin M; Krashias, George; Williams, Adam; Blattman, Joseph N; Greenberg, Philip D; Flavell, Richard A; Moghaddam, Amin E; Sheppard, Neil C; Sattentau, Quentin J

    2012-09-01

    Protection against mucosally transmitted infections probably requires immunity at the site of pathogen entry, yet there are no mucosal adjuvant formulations licensed for human use. Polyethyleneimine (PEI) represents a family of organic polycations used as nucleic acid transfection reagents in vitro and DNA vaccine delivery vehicles in vivo. Here we show that diverse PEI forms have potent mucosal adjuvant activity for viral subunit glycoprotein antigens. A single intranasal administration of influenza hemagglutinin or herpes simplex virus type-2 (HSV-2) glycoprotein D with PEI elicited robust antibody-mediated protection from an otherwise lethal infection, and was superior to existing experimental mucosal adjuvants. PEI formed nanoscale complexes with antigen, which were taken up by antigen-presenting cells in vitro and in vivo, promoted dendritic cell trafficking to draining lymph nodes and induced non-proinflammatory cytokine responses. PEI adjuvanticity required release of host double-stranded DNA that triggered Irf3-dependent signaling. PEI therefore merits further investigation as a mucosal adjuvant for human use. PMID:22922673

  10. Shoe allergic contact dermatitis.

    PubMed

    Matthys, Erin; Zahir, Amir; Ehrlich, Alison

    2014-01-01

    Foot dermatitis is a widespread condition, affecting men and women of all ages. Because of the location, this condition may present as a debilitating problem to those who have it. Allergic contact dermatitis involving the feet is frequently due to shoes or socks. The allergens that cause shoe dermatitis can be found in any constituent of footwear, including rubber, adhesives, leather, dyes, metals, and medicaments. The goal of treatment is to identify and minimize contact with the offending allergen(s). The lack of product information released from shoe manufacturers and the continually changing trends in footwear present a challenge in treating this condition. The aim of this study is to review the current literature on allergic contact shoe dermatitis; clinical presentation, allergens, patch testing, and management will be discussed. PubMed and MEDLINE databases were used for the search, with a focus on literature updates from the last 15 years. PMID:25000234

  11. Potent effects of dioscin against liver fibrosis.

    PubMed

    Zhang, Xiaoling; Han, Xu; Yin, Lianhong; Xu, Lina; Qi, Yan; Xu, Youwei; Sun, Huijun; Lin, Yuan; Liu, Kexin; Peng, Jinyong

    2015-01-01

    We previously reported the promising effects of dioscin against liver injury, but its effect on liver fibrosis remains unknown. The present work investigated the activities of dioscin against liver fibrosis and the underlying molecular mechanisms. Dioscin effectively inhibited the cell viabilities of HSC-T6, LX-2 and primary rat hepatic stellate cells (HSCs), but not hepatocytes. Furthermore, dioscin markedly increased peroxisome proliferator activated receptor-? (PPAR-?) expression and significantly reduced a-smooth muscle actin (?-SMA), transforming growth factor-?1 (TGF-?1), collagen ?1 (I) (COL1A1) and collagen ?1 (III) (COL3A1) levels in vitro. Notably, dioscin inhibited HSCs activation and induced apoptosis in activated HSCs. In vivo, dioscin significantly improved body weight and hydroxylproline, laminin, ?-SMA, TGF-?1, COL1A1 and COL3A1 levels, which were confirmed by histopathological assays. Dioscin facilitated matrix degradation, and exhibited hepatoprotective effects through the attenuation of oxidative stress and inflammation, in addition to exerting anti-fibrotic effects through the modulation of the TGF-?1/Smad, Wnt/?-catenin, mitogen-activated protein kinase (MAPK) and mitochondrial signaling pathways, which triggered the senescence of activated HSCs. In conclusion, dioscin exhibited potent effects against liver fibrosis through the modulation of multiple targets and signaling pathways and should be developed as a novel candidate for the treatment of liver fibrosis in the future. PMID:25853178

  12. Potent effects of dioscin against liver fibrosis

    PubMed Central

    Zhang, Xiaoling; Han, Xu; Yin, Lianhong; Xu, Lina; Qi, Yan; Xu, Youwei; Sun, Huijun; Lin, Yuan; Liu, Kexin; Peng, Jinyong

    2015-01-01

    We previously reported the promising effects of dioscin against liver injury, but its effect on liver fibrosis remains unknown. The present work investigated the activities of dioscin against liver fibrosis and the underlying molecular mechanisms. Dioscin effectively inhibited the cell viabilities of HSC-T6, LX-2 and primary rat hepatic stellate cells (HSCs), but not hepatocytes. Furthermore, dioscin markedly increased peroxisome proliferator activated receptor-γ (PPAR-γ) expression and significantly reduced a-smooth muscle actin (α-SMA), transforming growth factor-β1 (TGF-β1), collagen α1 (I) (COL1A1) and collagen α1 (III) (COL3A1) levels in vitro. Notably, dioscin inhibited HSCs activation and induced apoptosis in activated HSCs. In vivo, dioscin significantly improved body weight and hydroxylproline, laminin, α-SMA, TGF-β1, COL1A1 and COL3A1 levels, which were confirmed by histopathological assays. Dioscin facilitated matrix degradation, and exhibited hepatoprotective effects through the attenuation of oxidative stress and inflammation, in addition to exerting anti-fibrotic effects through the modulation of the TGF-β1/Smad, Wnt/β-catenin, mitogen-activated protein kinase (MAPK) and mitochondrial signaling pathways, which triggered the senescence of activated HSCs. In conclusion, dioscin exhibited potent effects against liver fibrosis through the modulation of multiple targets and signaling pathways and should be developed as a novel candidate for the treatment of liver fibrosis in the future. PMID:25853178

  13. Potent interaction of flavopiridol with MRP1

    PubMed Central

    Hooijberg, J H; Broxterman, H J; Scheffer, G L; Vrasdonk, C; Heijn, M; Jong, M C de; Scheper, R J; Lankelma, J; Pinedo, HM

    1999-01-01

    The multidrug resistance protein 1 (MRP1) is an ATP-dependent transport protein for organic anions, as well as neutral or positively charged anticancer agents. In this study we show that flavopiridol, a synthetic flavonoid currently studied in phase 1 trials for its anti-proliferative characteristics, interacts with MRP1 in a potent way. Flavopiridol, as well as other (iso)flavonoids stimulate the ATPase activity of MRP1 in a dose-dependent way at low micromolar concentrations. A new specific monoclonal antibody against MRP1 (MIB6) inhibits the (iso)flavonoid-induced ATPase activity of plasma membrane vesicles prepared from the MRP1 overexpressing cell line GLC4/ADR. The accumulation of daunorubicin in GLC4/ADR cells is increased by flavopiridol and by other non-glycosylated (iso)flavonoids that interact with MRP1 ATPase activity. However, flavopiridol is the only tested compound that affects the daunorubicin accumulation when present at concentrations below 1 μM. Glycosylated (iso)flavonoids do not affect MRP1-mediated transport or ATPase activity. Finally, MRP1 overexpressing and transfected cells are resistant to flavopiridol, but not to other (iso)flavonoids tested. These findings may be of relevance for the development of anticancer therapies with flavopiridol. © 1999 Cancer Research Campaign PMID:10496352

  14. Contact problem for a transversely isotropic half-space with an unknown contact region

    NASA Astrophysics Data System (ADS)

    Pozharskii, D. A.

    2014-03-01

    A three-dimensional contact problem with an unknown contact region for a transversely isotropic half-space, when the isotropy planes are perpendicular to the half-space boundary, is investigated. The method described makes it possible to evaluate effectively the Brinell and Vickers hardness and the contact strength of materials, the near-surface properties of which can substantially depend on the direction (titanium, zinc, beryllium, cobalt, aluminum and zinc oxides, graphite, wood, temoral bone, sapphire, etc; five elastic constants). We use the fact that the kernel of the integral equation of a contact problem can be represented in a form free of quadratures. Such a form of the kernel, in view of the simplicity of its regularization in singular points, makes it possible to apply the method of nonlinear boundary integral equations developed by Galanov to solve the contact problem with an unknown contact region. To debug the computer program, an exact solution of the contact problem for a stamp shaped like an elliptic paraboloid is used. Calculations are made for various materials with the incorporation of the stamp shaped as a rectangular pyramid. The contact regions, pressures, and the values of the impressing force with the specified stamp immersion are determined.

  15. Contact Interface Verification for DYNA3D Scenario 1: Basic Contact

    SciTech Connect

    McMichael, L D

    2006-05-10

    A suite of test problems has been developed to examine contact behavior within the nonlinear, three-dimensional, explicit finite element analysis (FEA) code DYNA3D (Lin, 2005). The test problems address the basic functionality of the contact algorithms, including the behavior of various kinematic, penalty, and Lagrangian enforcement formulations. The results from the DYNA3D analyses are compared to closed form solutions to verify the contact behavior. This work was performed as part of the Verification and Validation efforts of LLNL W Program within the NNSA's Advanced Simulation and Computing (ASC) Program. DYNA3D models the transient dynamic response of solids and structures including the interactions between disjoint bodies (parts). A wide variety of contact surfaces are available to represent the diverse interactions possible during an analysis, including relative motion (sliding), separation and gap closure (voids), and fixed relative position (tied). The problem geometry may be defined using a combination of element formulations, including one-dimensional beam and truss elements, two-dimensional shell elements, and three-dimensional solid elements. Consequently, it is necessary to consider various element interactions for each contact algorithm being verified. Most of the contact algorithms currently available in DYNA3D are examined; the exceptions are the Type 4--Single Surface Contact and Type 11--SAND algorithms. It is likely that these algorithms will be removed since their functionality is embodied in other, more robust, contact algorithms. The automatic contact algorithm is evaluated using the Type 12 interface. Two other variations of automatic contact, Type 13 and Type 14, offer additional means to adapt the interface domain, but share the same search and restoration algorithms as Type 12. The contact algorithms are summarized in Table 1. This report and associated test problems examine the scenario where one contact surface exists between two disjoint bodies. These test problems focus on whether a particular contact algorithm properly represents the interactions along the interface. A companion report (McMichael, 2006) and test problems address the multi-contact scenario in which multiple bodies interact with each other via multiple interfaces. The multi-contact test problems examine whether any ordering issues exist in the contact logic. The test problems are analyzed using version 5.2 (compiled on 12/22/2005) of DYNA3D. The analytical results are used to form baseline solutions for subsequent regression testing.

  16. Switchable telescopic contact lens.

    PubMed

    Tremblay, Eric J; Stamenov, Igor; Beer, R Dirk; Arianpour, Ashkan; Ford, Joseph E

    2013-07-01

    We present design and first demonstration of optics for a telescopic contact lens with independent optical paths for switching between normal and magnified vision. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8 x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision. We present an experimental demonstration of the contact lens mounted on a life-sized optomechanical model eye and, using a pair of modified commercial 3D television glasses, demonstrate electrically operated polarization switching between normal and magnified vision. PMID:23842384

  17. Religious Allergic Contact Dermatitis.

    PubMed

    Goldenberg, Alina; Matiz, Catalina; Eichenfield, Lawrence F

    2015-01-01

    Henna, derived from a combination of natural leaves and coloring additives, is a common decorative dye traditionally used in many Islamic religious celebrations. Para-phenylenediamine (PPD), a major component of black henna tattoo, is a strong sensitizer and common allergen. We report a case of severe connubial allergic contact dermatitis after black henna heterotransfer in a girl. PMID:25968562

  18. Thermal Contact Conductance

    NASA Technical Reports Server (NTRS)

    Salerno, Louis J.; Kittel, Peter

    1997-01-01

    The performance of cryogenic instruments is often a function of their operating temperature. Thus, designers of cryogenic instruments often are required to predict the operating temperature of each instrument they design. This requires accurate thermal models of cryogenic components which include the properties of the materials and assembly techniques used. When components are bolted or otherwise pressed together, a knowledge of the thermal performance of such joints are also needed. In some cases, the temperature drop across these joints represents a significant fraction of the total temperature difference between the instrument and its cooler. While extensive databases exist on the thermal properties of bulk materials, similar databases for pressed contacts do not. This has often lead to instrument designs that avoid pressed contacts or to the over-design of such joints at unnecessary expense. Although many people have made measurements of contact conductances at cryogenic temperatures, this data is often very narrow in scope and even more often it has not been published in an easily retrievable fashion, if published at all. This paper presents a summary of the limited pressed contact data available in the literature.

  19. [Contact allergies in musicians].

    PubMed

    Gasenzer, E R; Neugebauer, E A M

    2012-12-01

    During the last years, the problem of allergic diseases has increased. Allergies are errant immune responses to a normally harmless substance. In musicians the allergic contact dermatitis to exotic woods is a special problem. Exotic rosewood contains new flavonoids, which trigger an allergic reaction after permanent contact with the instrument. High quality woodwind instruments such as baroque flute or clarinets are made in ebony or palisander because of its great sound. Today instruments for non-professional players are also made in these exotic materials and non-professionals may have the risk to develop contact dermatitis, too. Brass-player has the risk of an allergic reaction to the different metals contained in the metal sheets of modern flutes and brass instruments. Specially nickel and brass alloys are used to product flute tubes or brass instruments. Special problem arises in children: patients who are allergic to plants or foods have a high risk to develop contact dermatitis. Parents don't know the materials of low-priced instruments for beginners. Often unknown cheap woods from exotic areas are used. Low-priced brass instruments contain high amount of brass and other cheap metals. Physicians should advice musician-patients or parents about the risks of the different materials and look for the reason of eczema on mouth, face, or hands. PMID:23233303

  20. Have Confidence in Contact

    ERIC Educational Resources Information Center

    Crisp, Richard J.; Turner, Rhiannon N.

    2010-01-01

    In an article in the May-June 2009 "American Psychologist," we discussed a new approach to reducing prejudice and encouraging more positive intergroup relations (Crisp & Turner, 2009). We named the approach imagined intergroup contact and defined it as "the mental simulation of a social interaction with a member or members of an outgroup category"…

  1. The Language Contact Profile

    ERIC Educational Resources Information Center

    Freed, Barbara F.; Dewey, Dan P.; Segalowitz, Norman; Halter, Randall

    2004-01-01

    Efforts to gather data of various sorts--demographics, language-learning history, contact with native speakers, use of the language in the field--as they relate to participants in SLA research studies are inherent to understanding more about language acquisition and use. Scholars frequently develop questionnaires of their own, which are rarely…

  2. Contact Efflorescence on Demand

    NASA Astrophysics Data System (ADS)

    Davis, R. D.; Lance, S.; Gordon, J. A.; Ushijima, S.; Tolbert, M. A.

    2014-12-01

    The phase state of atmospheric aerosols (liquid vs solid) plays an important role in particle growth, cloud formation, climate impact and visibility degradation. In the atmosphere, changes in relative humidity (RH) and temperature cause phase transitions in the atmospheric particulate. Efflorescence, the process of salt crystal nucleation from an aqueous electrolyte solution upon decreasing RH, often occurs at a lower RH than the reverse process of deliquescence. It has been shown that the efflorescence RH can occur at a higher RH in the presence of a heterogeneous surface immersed in a liquid particle. Here we present a new laboratory technique using optically levitated particles to study heterogeneous efflorescence initiated by contact with an external particle. In this work, collisions between aqueous microdroplets and heterogeneous nuclei are monitored in situ using scattered laser light to quantify the number of collisions and to detect phase transitions. We find that when contact initiates the phase transition, efflorescence occurs at a higher RH than when the same heterogeneous nucleus is immersed in the particle. The results of these experiments will be discussed in the context of understanding contact nucleation on a mechanistic level and predicting the relative importance of contact efflorescence in the atmosphere.

  3. Contact: Releasing the news

    NASA Astrophysics Data System (ADS)

    Pinotti, Roberto

    The problem of mass behavior after man's future contacts with other intelligences in the universe is not only a challenge for social scientists and political leaders all over the world, but also a cultural time bomb as well. In fact, since the impact of CETI (Contact with Extraterrestrial Intelligence) on human civilization, with its different cultures, might cause a serious socio-anthropological shock, a common and predetermined worldwide strategy is necessary in releasing the news after the contact, in order to keep possible manifestations of fear, panic and hysteria under control. An analysis of past studies in this field and of parallel historical situations as analogs suggests a definite "authority crisis" in the public as a direct consequence of an unexpected release of the news, involving a devastating "chain reaction" process (from both the psychological and sociological viewpoints) of anomie and maybe the collapse of today's society. The only way to prevent all this is to prepare the world's public opinion concerning contact before releasing the news, and to develop a long-term strategy through the combined efforts of scientists, political leaders, intelligence agencies and the mass media, in order to create the cultural conditions in which a confrontation with ETI won't affect mankind in a traumatic way. Definite roles and tasks in this multi-level model are suggested.

  4. Sifuvirtide, a potent HIV fusion inhibitor peptide

    SciTech Connect

    Wang, Rui-Rui; Yang, Liu-Meng; Wang, Yun-Hua; Pang, Wei; Department of Molecular Virology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080 ; Tam, Siu-Cheung; Tien, Po; Zheng, Yong-Tang

    2009-05-08

    Enfuvirtide (ENF) is currently the only FDA approved HIV fusion inhibitor in clinical use. Searching for more drugs in this category with higher efficacy and lower toxicity seems to be a logical next step. In line with this objective, a synthetic peptide with 36 amino acid residues, called Sifuvirtide (SFT), was designed based on the crystal structure of gp41. In this study, we show that SFT is a potent anti-HIV agent with relatively low cytotoxicity. SFT was found to inhibit replication of all tested HIV strains. The effective concentrations that inhibited 50% viral replication (EC{sub 50}), as determined in all tested strains, were either comparable or lower than benchmark values derived from well-known anti-HIV drugs like ENF or AZT, while the cytotoxic concentrations causing 50% cell death (CC{sub 50}) were relatively high, rendering it an ideal anti-HIV agent. A GST-pull down assay was performed to confirm that SFT is a fusion inhibitor. Furthermore, the activity of SFT on other targets in the HIV life cycle was also investigated, and all assays showed negative results. To further understand the mechanism of action of HIV peptide inhibitors, resistant variants of HIV-1{sub IIIB} were derived by serial virus passage in the presence of increasing doses of SFT or ENF. The results showed that there was cross-resistance between SFT and ENF. In conclusion, SFT is an ideal anti-HIV agent with high potency and low cytotoxicity, but may exhibit a certain extent of cross-resistance with ENF.

  5. Lithium-drifted silicon detector with segmented contacts

    DOEpatents

    Tindall, Craig S.; Luke, Paul N.

    2006-06-13

    A method and apparatus for creating both segmented and unsegmented radiation detectors which can operate at room temperature. The devices include a metal contact layer, and an n-type blocking contact formed from a thin layer of amorphous semiconductor. In one embodiment the material beneath the n-type contact is n-type material, such as lithium compensated silicon that forms the active region of the device. The active layer has been compensated to a degree at which the device may be fully depleted at low bias voltages. A p-type blocking contact layer, or a p-type donor material can be formed beneath a second metal contact layer to complete the device structure. When the contacts to the device are segmented, the device is capable of position sensitive detection and spectroscopy of ionizing radiation, such as photons, electrons, and ions.

  6. Exploring the Nature of Contact Freezing

    NASA Astrophysics Data System (ADS)

    Kiselev, A. A.; Hoffmann, N.; Duft, D.; Leisner, T.

    2012-12-01

    The freezing of supercooled water droplets upon contact with aerosol particles (contact nucleation of ice) is the least understood mechanism of ice formation in atmospheric clouds. Although experimental evidences suggest that some aerosols can be better IN in the contact than in the immersion mode (that is, triggering ice nucleation at higher temperature), no final explanation of this phenomena currently exists. On the other hand, the contact freezing is believed to be responsible for the enhanced rate of secondary ice formation occasionally observed in LIDAR measurements in the cold mixed phase clouds. Recently we have been able to show that the freezing of supercooled droplets electrodynamically levitated in the laminar flow containing mineral dust particles (kaolinite) is a process solely governed by a rate of collisions between the supercooled droplet and the aerosol particles. We have shown that the probability of droplet freezing on a single contact with aerosol particle may differ over an order of magnitude for kaolinite particles having different genesis and morphology. In this presentation we extend the study of contact nucleation of ice and compare the IN efficiency measured for DMA-selected kaolinite, illite and hematite particles. We show that the freezing probability increases towards unity as the temperature decreases and discuss the functional form of this temperature dependence. We explore the size dependence of the contact freezing probability and show that it scales with the surface area of the particles, thus resembling the immersion freezing behavior. However, for all minerals investigated so far, the contact freezing has been shown to dominate over immersion freezing on the short experimental time scales. Finally, based on the combined ESEM and electron microprobe analysis, we discuss the significance of particle morphology and variability of chemical composition on its IN efficiency in contact mode.

  7. Allergic contact dermatitis in children.

    PubMed

    Fontana, E; Belloni Fortina, A

    2014-12-01

    Allergic contact dermatitis is an inflammatory skin disease (delayed type hypersensitivity reaction) that accounts for up to 20% of all childhood dermatitis. Allergic contact dermatitis represents a clinical manifestation of contact sensitization and usually occurs at skin sites that have come into contact with the allergen. The clinical features of allergic contact dermatitis are itchy eczematous lesions. Prevalence of contact sensitization varies between 27% and 96% of children with suspected contact dermatitis. The relationship between contact sensitization and atopic dermatitis has been widely discussed but only conflicting data have been reported. Epicutaneous patch testing is the gold standard for the diagnosis of allergic contact dermatitis. The most common allergens detected in children are: metals, topical medicaments, fragrances, and preservatives. The first line management of allergic contact dermatitis in children is to avoid the offending allergens identified with the patch test and a topical corticosteroid therapy. PMID:25315290

  8. Contact Graph Routing

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.

    2011-01-01

    Contact Graph Routing (CGR) is a dynamic routing system that computes routes through a time-varying topology of scheduled communication contacts in a network based on the DTN (Delay-Tolerant Networking) architecture. It is designed to enable dynamic selection of data transmission routes in a space network based on DTN. This dynamic responsiveness in route computation should be significantly more effective and less expensive than static routing, increasing total data return while at the same time reducing mission operations cost and risk. The basic strategy of CGR is to take advantage of the fact that, since flight mission communication operations are planned in detail, the communication routes between any pair of bundle agents in a population of nodes that have all been informed of one another's plans can be inferred from those plans rather than discovered via dialogue (which is impractical over long one-way-light-time space links). Messages that convey this planning information are used to construct contact graphs (time-varying models of network connectivity) from which CGR automatically computes efficient routes for bundles. Automatic route selection increases the flexibility and resilience of the space network, simplifying cross-support and reducing mission management costs. Note that there are no routing tables in Contact Graph Routing. The best route for a bundle destined for a given node may routinely be different from the best route for a different bundle destined for the same node, depending on bundle priority, bundle expiration time, and changes in the current lengths of transmission queues for neighboring nodes; routes must be computed individually for each bundle, from the Bundle Protocol agent's current network connectivity model for the bundle s destination node (the contact graph). Clearly this places a premium on optimizing the implementation of the route computation algorithm. The scalability of CGR to very large networks remains a research topic. The information carried by CGR contact plan messages is useful not only for dynamic route computation, but also for the implementation of rate control, congestion forecasting, transmission episode initiation and termination, timeout interval computation, and retransmission timer suspension and resumption.

  9. A novel cyanobacterial nostocyclopeptide is a potent antitoxin against microcystins.

    PubMed

    Jokela, Jouni; Herfindal, Lars; Wahlsten, Matti; Permi, Perttu; Selheim, Frode; Vasconçelos, Vitor; Døskeland, Stein Ove; Sivonen, Kaarina

    2010-07-26

    Cyanobacterial hepatotoxins (microcystins and nodularins) cause numerous animal poisonings worldwide each year and are threats to human health. However, we found that extracts from several cyanobacteria isolates failed to induce hepatotoxicity even if they contained high concentrations of the liver toxin microcystin. The antitoxic activity abolishes all morphological hallmarks of microcystin-induced apoptosis, and therefore invalidates cell-based assays of the microcystin content of bloom-forming cyanobacteria. The antitoxin was purified from a cyanobacterial isolate (Nostoc sp. XSPORK 13A) from the Baltic Sea, and the activity was shown to reside in a novel cyclic peptide of the nostocyclopeptide family (nostocyclopeptide M1, Ncp-M1) that consists of seven amino acids (Tyr1-Tyr2-D-HSe3-L-Pro4-L-Val5-(2S,4S)-4-MPr6-Tyr7; MW=881) with an imino linkage between Tyr1 and Tyr7. Ncp-M1 did not compete with labelled microcystin for binding to protein phosphatase 2A; this explains why the antitoxin did not interfere with phosphatase-based microcystin assays. Currently used agents that interfere with microcystin action, such as inhibitors of ROS formation, microcystin uptake and Cam-kinase activity, are themselves inherently toxic. Since Ncp-M1 is potent and nontoxic it promises to become a useful mechanistic tool as soon as its exact cellular target is elucidated. PMID:20575133

  10. Carrier Selective, Passivated Contacts for High Efficiency Silicon Solar Cells based on Transparent Conducting Oxides

    DOE PAGESBeta

    Young, David L.; Nemeth, William; Grover, Sachit; Norman, Andrew; Yuan, Hao-Chih; Lee, Benjamin G.; LaSalvia, Vincenzo; Stradins, Paul

    2014-01-01

    We describe the design, fabrication and results of passivated contacts to n-type silicon utilizing thin SiO2 and transparent conducting oxide layers. High temperature silicon dioxide is grown on both surfaces of an n-type wafer to a thickness <50 Å, followed by deposition of tin-doped indium oxide (ITO) and a patterned metal contacting layer. As deposited, the thin-film stack has a very high J0,contact, and a non-ohmic, high contact resistance. However, after a forming gas anneal, the passivation quality and the contact resistivity improve significantly. The contacts are characterized by measuring the recombination parameter of the contact (J0,contact) and the specificmore » contact resistivity (ρcontact) using a TLM pattern. The best ITO/SiO2 passivated contact in this study has J0,contact = 92.5 fA/cm2 and ρcontact = 11.5 mOhm-cm2. These values are placed in context with other passivating contacts using an analysis that determines the ultimate efficiency and the optimal area fraction for contacts for a given set of (J0,contact, ρcontact) values. The ITO/SiO2 contacts are found to have a higher J0,contact, but a similar ρcontact compared to the best reported passivated contacts.« less

  11. Contact dependent growth inhibition of E. coli O157:H7 by EC869 CDI system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Contact Dependent Growth Inhibition (CDI) is a recently discovered mechanism that microorganisms use to compete in various microecosystems. CDI systems express large cell surface exposed CdiA proteins with potent antimicrobial peptide tips. Many CDI systems also contain additional down...

  12. Contact dynamics math model

    NASA Technical Reports Server (NTRS)

    Glaese, John R.; Tobbe, Patrick A.

    1986-01-01

    The Space Station Mechanism Test Bed consists of a hydraulically driven, computer controlled six degree of freedom (DOF) motion system with which docking, berthing, and other mechanisms can be evaluated. Measured contact forces and moments are provided to the simulation host computer to enable representation of orbital contact dynamics. This report describes the development of a generalized math model which represents the relative motion between two rigid orbiting vehicles. The model allows motion in six DOF for each body, with no vehicle size limitation. The rotational and translational equations of motion are derived. The method used to transform the forces and moments from the sensor location to the vehicles' centers of mass is also explained. Two math models of docking mechanisms, a simple translational spring and the Remote Manipulator System end effector, are presented along with simulation results. The translational spring model is used in an attempt to verify the simulation with compensated hardware in the loop results.

  13. Contact dermatitis from propolis.

    PubMed

    Wanscher, B

    1976-04-01

    Two patients with contact dermatitis due to the natural product propolis (bee glue) are reported. They presented perioral eczema and stomatitis which were recalcitrant until propolis was considered as the cause. Patch tests with propolis preparations were positive in both patients, and, furthermore, in the second patient the lesions relapsed after provocation tests. European standard patch test including balsam of Peru were negative. The complexity of propolis, its supposed anti-inflammatory effect due to flavonoids, and the sensitizing agents originating mainly from the poplar trees are discussed together with the cross-sensitization to balsam of Peru. Contact dermatitis due to propolis should be considered in unexplained eczemas, mainly perioral but also in other areas, as propolis preparations are available also as ointments and cosmetic creams. PMID:1268058

  14. Contact stress sensor

    DOEpatents

    Kotovsky, Jack

    2012-02-07

    A contact stress sensor includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a thermal compensator and a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  15. Contact stress sensor

    DOEpatents

    Kotovsky, Jack

    2014-02-11

    A method for producing a contact stress sensor that includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  16. Experimental investigation on the electrical contact behavior of rolling contact connector.

    PubMed

    Chen, Junxing; Yang, Fei; Luo, Kaiyu; Zhu, Mingliang; Wu, Yi; Rong, Mingzhe

    2015-12-01

    Rolling contact connector (RCC) is a new technology utilized in high performance electric power transfer systems with one or more rotating interfaces, such as radars, satellites, wind generators, and medical computed tomography machines. Rolling contact components are used in the RCC instead of traditional sliding contacts to transfer electrical power and/or signal. Since the requirement of the power transmission is increasing in these years, the rolling electrical contact characteristics become more and more important for the long-life design of RCC. In this paper, a typical form of RCC is presented. A series of experimental work are carried out to investigate the rolling electrical contact characteristics during its lifetime. The influence of a variety of factors on the electrical contact degradation behavior of RCC is analyzed under both vacuum and air environment. Based on the surface morphology and elemental composition changes in the contact zone, which are assessed by field emission scanning electron microscope and confocal laser scanning microscope, the mechanism of rolling electrical contact degradation is discussed. PMID:26724076

  17. Experimental investigation on the electrical contact behavior of rolling contact connector

    NASA Astrophysics Data System (ADS)

    Chen, Junxing; Yang, Fei; Luo, Kaiyu; Zhu, Mingliang; Wu, Yi; Rong, Mingzhe

    2015-12-01

    Rolling contact connector (RCC) is a new technology utilized in high performance electric power transfer systems with one or more rotating interfaces, such as radars, satellites, wind generators, and medical computed tomography machines. Rolling contact components are used in the RCC instead of traditional sliding contacts to transfer electrical power and/or signal. Since the requirement of the power transmission is increasing in these years, the rolling electrical contact characteristics become more and more important for the long-life design of RCC. In this paper, a typical form of RCC is presented. A series of experimental work are carried out to investigate the rolling electrical contact characteristics during its lifetime. The influence of a variety of factors on the electrical contact degradation behavior of RCC is analyzed under both vacuum and air environment. Based on the surface morphology and elemental composition changes in the contact zone, which are assessed by field emission scanning electron microscope and confocal laser scanning microscope, the mechanism of rolling electrical contact degradation is discussed.

  18. Experimental investigation on the electrical contact behavior of rolling contact connector

    SciTech Connect

    Chen, Junxing; Yang, Fei Luo, Kaiyu; Zhu, Mingliang; Wu, Yi; Rong, Mingzhe

    2015-12-15

    Rolling contact connector (RCC) is a new technology utilized in high performance electric power transfer systems with one or more rotating interfaces, such as radars, satellites, wind generators, and medical computed tomography machines. Rolling contact components are used in the RCC instead of traditional sliding contacts to transfer electrical power and/or signal. Since the requirement of the power transmission is increasing in these years, the rolling electrical contact characteristics become more and more important for the long-life design of RCC. In this paper, a typical form of RCC is presented. A series of experimental work are carried out to investigate the rolling electrical contact characteristics during its lifetime. The influence of a variety of factors on the electrical contact degradation behavior of RCC is analyzed under both vacuum and air environment. Based on the surface morphology and elemental composition changes in the contact zone, which are assessed by field emission scanning electron microscope and confocal laser scanning microscope, the mechanism of rolling electrical contact degradation is discussed.

  19. Pediatric contact dermatitis.

    PubMed

    Sharma, Vinod K; Asati, Dinesh P

    2010-01-01

    Allergic contact dermatitis (ACD) in children, until recently, was considered rare. ACD was considered as a disorder of the adult population and children were thought to be spared due to a lack of exposure to potential allergens and an immature immune system. Prevalence of ACD to even the most common allergens in children, like poison ivy and parthenium, is relatively rare as compared to adults. However, there is now growing evidence of contact sensitization of the pediatric population, and it begins right from early childhood, including 1-week-old neonates. Vaccinations, piercing, topical medicaments and cosmetics in younger patients are potential exposures for sensitization. Nickel is the most common sensitizer in almost all studies pertaining to pediatric contact dermatitis. Other common allergens reported are cobalt, fragrance mix, rubber, lanolin, thiomersol, neomycin, gold, mercapto mix, balsum of Peru and colophony. Different factors like age, sex, atopy, social and cultural practices, habit of parents and caregivers and geographic changes affect the patterns of ACD and their variable clinical presentation. Patch testing should be considered not only in children with lesions of a morphology suggestive of ACD, but in any child with dermatitis that is difficult to control. PMID:20826990

  20. Functional modular contact lens

    NASA Astrophysics Data System (ADS)

    Shum, Angela J.; Cowan, Melissa; Lähdesmäki, Ilkka; Lingley, Andrew; Otis, Brian; Parviz, Babak A.

    2009-08-01

    Tear fluid offers a potential route for non-invasive sensing of physiological parameters. Utilization of this potential depends on the ability to manufacture sensors that can be placed on the surface of the eye. A contact lens makes a natural platform for such sensors, but contact lens polymers present a challenge for sensor fabrication. This paper describes a microfabrication process for constructing sensors that can be integrated into the structure of a functional contact lens in the future. To demonstrate the capabilities of the process, an amperometric glucose sensor was fabricated on a polymer substrate. The sensor consists of platinum working and counter electrodes, as well as a region of indium-tin oxide (ITO) for glucose oxidase immobilization. An external silver-silver chloride electrode was used as the reference electrode during the characterization experiments. Sensor operation was validated by hydrogen peroxide measurements in the 10- 20 μM range and glucose measurements in the 0.125-20 mM range.

  1. Relaxation damping in oscillating contacts

    NASA Astrophysics Data System (ADS)

    Popov, M.; Popov, V. L.; Pohrt, R.

    2015-11-01

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect “relaxation damping”. The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed.

  2. Obituary--rigid contact lenses.

    PubMed

    Efron, Nathan

    2010-10-01

    Scleral and corneal rigid lenses represented 100 per cent of the contact lens market immediately prior to the invention of soft lenses in the mid-1960s. In the United Kingdom today, rigid lenses comprise 2 per cent of all new lens fits. Low rates of rigid lens fitting are also apparent in 27 other countries which have recently been surveyed. Thus, the 1998 prediction of the author that rigid lenses--also referred to as 'rigid gas permeable' (RGP) lenses or 'gas permeable' (GP) lenses--would be obsolete by the year 2010 has essentially turned out to be correct. In this obituary, the author offers 10 reasons for the demise of rigid lens fitting: initial rigid lens discomfort; intractable rigid lens-induced corneal and lid pathology; extensive soft lens advertising; superior soft lens fitting logistics; lack of rigid lens training opportunities; redundancy of the rigid lens 'problem solver' function; improved soft toric and bifocal/varifocal lenses; limited uptake of orthokeratology; lack of investment in rigid lenses; and the emergence of aberration control soft lenses. Rigid lenses are now being fitted by a minority of practitioners with specialist skills/training. Certainly, rigid lenses can no longer be considered as a mainstream form of contact lens correction. May their dear souls (bulk properties) rest in peace. PMID:20674469

  3. Relaxation damping in oscillating contacts

    PubMed Central

    Popov, M.; Popov, V.L.; Pohrt, R.

    2015-01-01

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect “relaxation damping”. The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed. PMID:26549011

  4. [Systemic contact eczema against Balsam of Peru].

    PubMed

    Pfützner, Wolfgang; Niedermeier, Andrea; Thomas, Peter; Przybilla, Bernhard

    2003-09-01

    Balsam of Peru (PB; Myroxylon pereirae) is a natural product derived from resin of a tropical tree (MyroxyIon balsamum (L.) Harms var. pereirae (Royle) Baillon). Because of its antiseptic and aromatic properties PB or PB-components can be found worldwide not only in many health care and cosmetic products, but also in food items and semiluxury food. PB contains a wide variety of potent contact allergens leading to hypersensitivity reactions not only after topical application but also oral uptake. We report a 51-year-old brewer with chronic eczema of the hands who showed delayed-type patch test reactions against PB and fragrance-mix. Oral PB-challenge led to exacerbation of the eczema 5 and in a repeated test 2 days later. We here review this probably quite often overlooked disease and the therapeutic consequences which require profound knowledge about the wide distribution of PB when advising the patient about a PB-restricted diet. In addition, this unusual case report demonstrates that one has to consider marked delayed hypersensitivity reaction when investigating a systemic contact allergy. PMID:16285279

  5. Time domain contact model for tyre/road interaction including nonlinear contact stiffness due to small-scale roughness

    NASA Astrophysics Data System (ADS)

    Andersson, P. B. U.; Kropp, W.

    2008-11-01

    Rolling resistance, traction, wear, excitation of vibrations, and noise generation are all attributes to consider in optimisation of the interaction between automotive tyres and wearing courses of roads. The key to understand and describe the interaction is to include a wide range of length scales in the description of the contact geometry. This means including scales on the order of micrometres that have been neglected in previous tyre/road interaction models. A time domain contact model for the tyre/road interaction that includes interfacial details is presented. The contact geometry is discretised into multiple elements forming pairs of matching points. The dynamic response of the tyre is calculated by convolving the contact forces with pre-calculated Green's functions. The smaller-length scales are included by using constitutive interfacial relations, i.e. by using nonlinear contact springs, for each pair of contact elements. The method is presented for normal (out-of-plane) contact and a method for assessing the stiffness of the nonlinear springs based on detailed geometry and elastic data of the tread is suggested. The governing equations of the nonlinear contact problem are solved with the Newton-Raphson iterative scheme. Relations between force, indentation, and contact stiffness are calculated for a single tread block in contact with a road surface. The calculated results have the same character as results from measurements found in literature. Comparison to traditional contact formulations shows that the effect of the small-scale roughness is large; the contact stiffness is only up to half of the stiffness that would result if contact is made over the whole element directly to the bulk of the tread. It is concluded that the suggested contact formulation is a suitable model to include more details of the contact interface. Further, the presented result for the tread block in contact with the road is a suitable input for a global tyre/road interaction model that is also based on the presented contact formulation.

  6. A silver nanocomposite biomaterial for blood-contacting implants.

    PubMed

    de Mel, Achala; Chaloupka, Karla; Malam, Yogeshkumar; Darbyshire, Arnold; Cousins, Brian; Seifalian, Alexander M

    2012-09-01

    Cardiovascular implants must resist infection and thrombosis. A nanocomposite polymeric material [polyhedral-oligomeric-silsesquioxane-poly(carbonate-urea)urethane; POSS-PCU] demonstrates ideal properties for cardiovascular applications. Silver nanoparticles or nanosilver (NS) are recognized for efficient antibacterial properties. This study aims to determine the influence of NS integrated POSS-PCU on thrombogenicity. Silver nitrate was reduced with dimethylformamide and stabilized by the inclusion of fumed silica nanoparticles to prevent aggregation of NS and were incorporated into POSS-PCU to form a range of POSS-PCU-NS concentrations (by weight); 0.20% (NS16), 0.40% (NS32), 0.75% (NS64), and 1.50% (NS128). Surface wettability was determined with sessile-drop water contact angles. Platelets were introduced onto test samples and Alamar Blue (AB), mitochondrial-activity assay, quantified the degree of platelet adhesion whilst platelet-factor-4 (PF4) ELISA quantified the degree of platelet activation. Thromboelastography (TEG) determined the profiles of whole blood kinetics while hemolysis assay demonstrated the degree of blood compatibility. Increasing levels of NS induced greater hydrophilicity. A concentration dependant decrease in platelet adhesion and activation was observed with AB and PF4 readings, respectively. TEG demonstrated that the antithrombogenic properties of POSS-PCU were retained with POSS-PCU-NS16, and enhanced with POSS-PCU-NS32, but was reduced with POSS-PCU-NS64 and POSS-PCU-NS128. POSS-PCU-NS64 and POSS-PCU-NS128 demonstrated a hemolytic tendency, but no hemolysis was observed with POSS-PCU-NS16 and POSS-PCU-NS32. Overall, POSS-PCU-NS32 rendered potent antithrombogenic properties. PMID:22528182

  7. Dual contact pogo pin assembly

    DOEpatents

    Hatch, Stephen McGarry

    2015-01-20

    A contact assembly includes a base and a pair of electrical contacts supported by the base. A first end of the first electrical contact corresponds to a first end of the base and is configured to engage a first external conductive circuit element. A first end of the second electrical contact also corresponds to the first end of the base and is configured to engage a second external conductive circuit element. The first contact and the second contact are electrically isolated from one another and configured to compress when engaging an external connector element. The base includes an aperture positioned on a second end of the base outboard of a second end of the first and second electrical contacts. The aperture presents a narrowing shape with a wide mouth distal the electrical contacts and a narrow internal through-hole proximate the electrical contacts.

  8. Structures of Potent Selective Peptide Mimetics Bound to Carboxypeptidase B

    SciTech Connect

    Adler, M.; Buckman, B.; Bryant, J.; Chang, Z.; Chu, K.; Emayan, K.; Hrvatin, P.; Islam, I.; Morser, J.; Sukovich, D.; West, C.; Yuan, S.; Whitlow, M.

    2009-05-11

    This article reports the crystal structures of inhibitors of the functional form of thrombin-activatable fibrinolysis inhibitor (TAFIa). In vivo experiments indicate that selective inhibitors of TAFIa would be useful in the treatment of heart attacks. Since TAFIa rapidly degrades in solution, the homologous protein porcine pancreatic carboxypeptidase B (pp-CpB) was used in these crystallography studies. Both TAFIa and pp-CpB are zinc-based exopeptidases that are specific for basic residues. The final development candidate, BX 528, is a potent inhibitor of TAFIa (2 nM) and has almost no measurable effect on the major selectivity target, carboxypeptidase N. BX 528 was designed to mimic the tripeptide Phe-Val-Lys. A sulfonamide replaces the Phe-Val amide bond and a phosphinate connects the Val and Lys groups. The phosphinate also chelates the active-site zinc. The electrostatic interactions with the protein mimic those of the natural substrate. The primary amine in BX 528 forms a salt bridge to Asp255 at the base of the S1 pocket. The carboxylic acid interacts with Arg145 and the sulfonamide is hydrogen bonded to Arg71. Isopropyl and phenyl groups replace the side chains of Val and Phe, respectively. A series of structures are presented here that illustrate the evolution of BX 528 from thiol-based inhibitors that mimic a free C-terminal arginine. The first step in development was the replacement of the thiol with a phosphinate. This caused a precipitous drop in binding affinity. Potency was reclaimed by extending the inhibitors into the downstream binding sites for the natural substrate.

  9. Single-contact tunneling thermometry

    DOEpatents

    Maksymovych, Petro

    2016-02-23

    A single-contact tunneling thermometry circuit includes a tunnel junction formed between two objects. Junction temperature gradient information is determined based on a mathematical relationship between a target alternating voltage applied across the junction and the junction temperature gradient. Total voltage measured across the junction indicates the magnitude of the target alternating voltage. A thermal gradient is induced across the junction. A reference thermovoltage is measured when zero alternating voltage is applied across the junction. An increasing alternating voltage is applied while measuring a thermovoltage component and a DC rectification voltage component created by the applied alternating voltage. The target alternating voltage is reached when the thermovoltage is nullified or doubled by the DC rectification voltage depending on the sign of the reference thermovoltage. Thermoelectric current and current measurements may be utilized in place of the thermovoltage and voltage measurements. The system may be automated with a feedback loop.

  10. Multiscale electrical contact resistance in clustered contact distribution

    NASA Astrophysics Data System (ADS)

    Lee, Sangyoung; Cho, Hyun; Jang, Yong Hoon

    2009-08-01

    For contact between rough surfaces of conductors in which a clustered contact spot distribution is dominant through a multiscale process, electrical contact resistance (ECR) is analysed using a smoothed version of Greenwood's model (Jang and Barber 2003 J. Appl. Phys. 94 7215), which is extended to estimate the statistical distribution of contact spots considering the size and the location simultaneously. The application of this statistical method to a contact spot distribution, generated by the finite element method using a fractal surface defined by the random midpoint displacement algorithm, identifies the effect of the clustered contact distribution on ECR, showing that including a finer scale in the fractal contact surface causes the predicted resistance to approach a finite limit. It is also confirmed that the results are close to that of Barber's analogy (Barber 2003 Proc. R. Soc. Lond. A 459 53) regarding incremental stiffness and conductance for elastic contact.

  11. Can Imagined Interactions Produce Positive Perceptions?: Reducing Prejudice through Simulated Social Contact

    ERIC Educational Resources Information Center

    Crisp, Richard J.; Turner, Rhiannon N.

    2009-01-01

    The contact hypothesis states that, under the right conditions, contact between members of different groups leads to more positive intergroup relations. The authors track recent trends in contact theory to the emergence of extended, or indirect, forms of contact. These advances lead to an intriguing proposition: that simply imagining intergroup…

  12. Can Imagined Interactions Produce Positive Perceptions?: Reducing Prejudice through Simulated Social Contact

    ERIC Educational Resources Information Center

    Crisp, Richard J.; Turner, Rhiannon N.

    2009-01-01

    The contact hypothesis states that, under the right conditions, contact between members of different groups leads to more positive intergroup relations. The authors track recent trends in contact theory to the emergence of extended, or indirect, forms of contact. These advances lead to an intriguing proposition: that simply imagining intergroup

  13. Contact dermatitis in printing tradesmen.

    PubMed

    Nethercott, J R; Nosal, R

    1986-05-01

    During a 2-year period in Toronto, Canada, 21 printing tradesmen with contact dermatitis were evaluated. 67% had allergic contact dermatitis; 29% due to ultraviolet-cured ink components. Irritant contact dermatitis accounted for 37% of the cases. The prognosis in printing tradesmen with contact dermatitis is guarded, except for those with allergic contact dermatitis due to UV-cured components, as the tradesmen who were sensitized to other contactants eventually left the trade. Offset lithography was associated with the problem in 18 of the 21 cases. A brief outline is given of the printing processes in common use. PMID:2943556

  14. Electrical contacts for a thin-film semiconductor device

    DOEpatents

    Carlson, David E.; Dickson, Charles R.; D'Aiello, Robert V.

    1989-08-08

    A method of fabricating spaced-apart back contacts on a thin film of semiconductor material by forming strips of buffer material on top of the semiconductor material in locations corresponding to the desired dividing lines between back contacts, forming a film of metal substantially covering the semiconductor material and buffer strips, and scribing portions of the metal film overlying the buffer strips with a laser without contacting the underlying semiconductor material to separate the metal layer into a plurality of back contacts. The buffer material serves to protect the underlying semiconductor material from being damaged during the laser scribing. Back contacts and multi-cell photovoltaic modules incorporating such back contacts also are disclosed.

  15. Highly potent and selective pyrazolylpyrimidines as Syk kinase inhibitors.

    PubMed

    Choi, Jang-Sik; Hwang, Hae-Jun; Kim, Se-Won; Lee, Byung Il; Lee, Jaekyoo; Song, Ho-Juhn; Koh, Jong Sung; Kim, Jung-Ho; Lee, Phil Ho

    2015-10-15

    A series of pyrazolylpyrimidine scaffold based Syk inhibitors were synthesized and evaluated for their biological activities and selectivity. Lead optimization efforts provided compounds with potent Syk inhibition in both enzymatic and TNF-α release assay. PMID:26384287

  16. Copper Reduction and Contact Killing of Bacteria by Iron Surfaces

    PubMed Central

    Mathews, Salima; Kumar, Ranjeet

    2015-01-01

    The well-established killing of bacteria by copper surfaces, also called contact killing, is currently believed to be a combined effect of bacterial contact with the copper surface and the dissolution of copper, resulting in lethal bacterial damage. Iron can similarly be released in ionic form from iron surfaces and would thus be expected to also exhibit contact killing, although essentially no contact killing is observed by iron surfaces. However, we show here that the exposure of bacteria to iron surfaces in the presence of copper ions results in efficient contact killing. The process involves reduction of Cu2+ to Cu+ by iron; Cu+ has been shown to be considerably more toxic to cells than Cu2+. The specific Cu+ chelator, bicinchoninic acid, suppresses contact killing by chelating the Cu+ ions. These findings underline the importance of Cu+ ions in the contact killing process and infer that iron-based alloys containing copper could provide novel antimicrobial materials. PMID:26150470

  17. Copper Reduction and Contact Killing of Bacteria by Iron Surfaces.

    PubMed

    Mathews, Salima; Kumar, Ranjeet; Solioz, Marc

    2015-09-01

    The well-established killing of bacteria by copper surfaces, also called contact killing, is currently believed to be a combined effect of bacterial contact with the copper surface and the dissolution of copper, resulting in lethal bacterial damage. Iron can similarly be released in ionic form from iron surfaces and would thus be expected to also exhibit contact killing, although essentially no contact killing is observed by iron surfaces. However, we show here that the exposure of bacteria to iron surfaces in the presence of copper ions results in efficient contact killing. The process involves reduction of Cu(2+) to Cu(+) by iron; Cu(+) has been shown to be considerably more toxic to cells than Cu(2+). The specific Cu(+) chelator, bicinchoninic acid, suppresses contact killing by chelating the Cu(+) ions. These findings underline the importance of Cu(+) ions in the contact killing process and infer that iron-based alloys containing copper could provide novel antimicrobial materials. PMID:26150470

  18. Azachalcones: a new class of potent polyphenol oxidase inhibitors.

    PubMed

    Radhakrishnan, Sini Karanayil; Shimmon, Ronald Gibrial; Conn, Costa; Baker, Anthony T

    2015-04-15

    A library of potent inhibitors of polyphenol oxidase and their structure activity relationships are described. Azachalcone derivatives were synthesized and tested for their tyrosinase inhibitory activity. Their inhibitory activities on mushroom tyrosinase using l-DOPA as a substrate were investigated. Two compounds that are the reduction congeners of the pyridinyl azachalcones strongly inhibited the enzyme activity and were more potent than the positive control kojic acid. PMID:25782744

  19. Contact nuclei formation in aqueous dextrose solutions

    NASA Astrophysics Data System (ADS)

    Cerreta, Michael K.; Berglund, Kris A.

    1990-06-01

    A laser Raman microprobe was used in situ to observe the growth of alpha dextrose monohydrate on alpha anhydrous dextrose crystals. The Raman spectra indicate growth of the monohydrate below 28.1°C, but the presence of only the anhydrous form above 40.5°C. Contact nucleation experiments with parent anhydrous crystals yielded only monohydrate nuclei below 28.1°C, while contacts in solutions between 34.5 and 41.0°C produced both crystalline forms, and contacts in solutions above 43.5°C produced only anhydrous nuclei. The inability of the monohydrate to grow on anhydrous crystals in the same solution that forms the two crystalline phases with a single contact precludes a simple attrition mechanism of nuclei formation. For the same reason, the hypothetical mechanism involving parent crystal stabilization of pre-crystalline clusters, allowing the clusters to grow into nuclei, is also contradicted. A third, mechanism, which may be a combination of the two, is believed to apply.

  20. Contact resistivities of metal-insulator-semiconductor contacts and metal-semiconductor contacts

    NASA Astrophysics Data System (ADS)

    Yu, Hao; Schaekers, Marc; Barla, Kathy; Horiguchi, Naoto; Collaert, Nadine; Thean, Aaron Voon-Yew; De Meyer, Kristin

    2016-04-01

    Applying simulations and experiments, this paper systematically compares contact resistivities (ρc) of metal-insulator-semiconductor (MIS) contacts and metal-semiconductor (MS) contacts with various semiconductor doping concentrations (Nd). Compared with the MS contacts, the MIS contacts with the low Schottky barrier height are more beneficial for ρc on semiconductors with low Nd, but this benefit diminishes gradually when Nd increases. With high Nd, we find that even an "ideal" MIS contact with optimized parameters cannot outperform the MS contact. As a result, the MIS contacts mainly apply to devices that use relatively low doped semiconductors, while we need to focus on the MS contacts to meet the sub-1 × 10-8 Ω cm2 ρc requirement for future Complementary Metal-Oxide-Semiconductor (CMOS) technology.

  1. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  2. Contact dermatitis to methylisothiazolinone.

    PubMed

    Scherrer, Maria Antonieta Rios; Rocha, Vanessa Barreto; Andrade, Ana Regina Coelho

    2015-12-01

    Methylisothiazolinone (MI) is a preservative found in cosmetic and industrial products. Contact dermatitis caused by either methylchloroisothiazolinone/methylisothiazolinone (MCI/MI or Kathon CG) or MI has shown increasing frequency. The latter is preferably detected through epicutaneous testing with aqueous MI 2000 ppm, which is not included in the Brazilian standard tray. We describe a series of 23 patients tested using it and our standard tray. A case with negative reaction to MCI/MI and positive to MI is emphasized. PMID:26734880

  3. Contact dermatitis to methylisothiazolinone*

    PubMed Central

    Scherrer, Maria Antonieta Rios; Rocha, Vanessa Barreto; Andrade, Ana Regina Coelho

    2015-01-01

    Methylisothiazolinone (MI) is a preservative found in cosmetic and industrial products. Contact dermatitis caused by either methylchloroisothiazolinone/methylisothiazolinone (MCI/MI or Kathon CG) or MI has shown increasing frequency. The latter is preferably detected through epicutaneous testing with aqueous MI 2000 ppm, which is not included in the Brazilian standard tray. We describe a series of 23 patients tested using it and our standard tray. A case with negative reaction to MCI/MI and positive to MI is emphasized. PMID:26734880

  4. Novel, potent anti-androgens of therapeutic potential: recent advances and promising developments.

    PubMed

    Vasaitis, Tadas S; Njar, Vincent C O

    2010-04-01

    The beneficial effect of androgen ablation has been well established in prostate cancer therapy. Despite the initial response, patients typically relapse with a more aggressive form described as castration-resistant prostate cancer (CRCP), driven by continued androgen receptor (AR) signaling. This review details the current state of anti-androgen therapy, mainly for CRPC, with major emphasis on the most potent and promising compounds under development. Anti-androgen failure has been linked to elevated AR expression, increased expression of coactivator proteins, AR mutations, ligand-independent AR activation and persistent intraprostatic androgens. MDV3100, BMS-641988 and VN/124-1 were developed to overcome these mechanisms. In CRCP, prostate cancer cells still rely on intracellular androgens and, to a greater extent, on active AR for growth and survival. Therefore, potent anti-androgens that efficiently disrupt the functions (signaling) of AR are envisioned to be effective drugs for all types of prostate cancers. PMID:21426013

  5. Contact Lenses in the Laboratory.

    ERIC Educational Resources Information Center

    Kingston, David W.

    1981-01-01

    Summarizes results of a three-item questionnaire returned by 43 Michigan institutions expressing views on wearing contact lenses in chemical laboratories. Questions focused on eye protection, type of protection, and use of contact lenses. (SK)

  6. Ecosystemic approach to contact dermatitis.

    PubMed

    Stransky, L

    1989-01-01

    Contact dermatitis is looked upon as an ecosystem, including the allgergens from environment and the mechanisms of contact sensitivity. The methods of investigation and the indirect immunological tests are methodologically discussed by ecosystemic approach. PMID:2731628

  7. Allergic Contact Dermatitis

    PubMed Central

    Nelson, Jenny L.

    2010-01-01

    Epicutaneous patch testing is the gold standard method for the diagnosis of allergic contact dermatitis. Despite this knowledge, many clinical dermatologists do not offer patch testing in their offices or offer testing with only a limited number of allergens. Introduced in 1995, the Thin-Layer Rapid Use Epicutaneous Test originally contained 23 allergens and one control. In 2007, five additional allergens were added. This United States Food and Drug Administration-approved patch testing system made patch testing more convenient, and after its introduction, more dermatologists offered patch testing services. However, the number of allergens in the Thin-Layer Rapid Use Epicutaneous Test remains relatively low. Every two years, the North American Contact Dermatitis Group collects and reports the data from patch testing among its members to a standardized series of allergens. In 2005-2006, the Group used a series of 65 allergens. Of the top 30 allergens reported in 2005-2006, 10 were not included in the Thin-Layer Rapid Use Epicutaneous Test. Knowledge of and testing for additional allergens such as these may increase patch testing yield. PMID:20967194

  8. Metal Silicides: Active elements of ULSI contacts

    NASA Astrophysics Data System (ADS)

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

    1996-11-01

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

  9. Contact position sensor using constant contact force control system

    NASA Technical Reports Server (NTRS)

    Sturdevant, Jay (Inventor)

    1995-01-01

    A force control system (50) and method are provided for controlling a position contact sensor (10) so as to produce a constant controlled contact force therewith. The system (50) includes a contact position sensor (10) which has a contact probe (12) for contacting the surface of a target to be measured and an output signal (V.sub.o) for providing a position indication thereof. An actuator (30) is provided for controllably driving the contact position sensor (10) in response to an actuation control signal (I). A controller (52) receives the position indication signal (V.sub.o) and generates in response thereto the actuation control signal (I) so as to provide a substantially constant selective force (F) exerted by the contact probe (12). The actuation drive signal (I) is generated further in response to substantially linear approximation curves based on predetermined force and position data attained from the sensor (10) and the actuator (30).

  10. Spanish in Four Continents: Studies in Language Contact and Bilingualism.

    ERIC Educational Resources Information Center

    Silva-Corvalan, Carmen, Ed.

    Papers on Spanish bilingualism and Spanish in contact with other languages include: "The Study of Language Contact: An Overview of the Issues" (Carmen Silva-Corvalan); "Language Mixture: Ordinary Processes, Extraordinary Results" (Sarah G. Thomason); "The Impact of Quichua on Verb Forms Used in Spanish Requests in Otavalo, Ecuador" (Joni Kay…

  11. Polymer-Metal Schottky Contact with Direct-Current Outputs.

    PubMed

    Shao, Hao; Fang, Jian; Wang, Hongxia; Dai, Liming; Lin, Tong

    2016-02-01

    A freestanding conducting polymer plate with one side forming a Schottky contact and the other side an Ohmic contact with two different metal electrodes can generate a DC voltage with an output current density as high as 218.6 μA cm(-2) upon mechanical deformation. PMID:26639910

  12. Potent Antiscrapie Activities of Degenerate Phosphorothioate Oligonucleotides

    PubMed Central

    Kocisko, David A.; Vaillant, Andrew; Lee, Kil Sun; Arnold, Kevin M.; Bertholet, Nadine; Race, Richard E.; Olsen, Emily A.; Juteau, Jean-Marc; Caughey, Byron

    2006-01-01

    Although transmissible spongiform encephalopathies (TSEs) are incurable, a key therapeutic approach is prevention of conversion of the normal, protease-sensitive form of prion protein (PrP-sen) to the disease-specific protease-resistant form of prion protein (PrP-res). Here degenerate phosphorothioate oligonucleotides (PS-ONs) are introduced as low-nM PrP-res conversion inhibitors with strong antiscrapie activities in vivo. Comparisons of various PS-ON analogs indicated that hydrophobicity and size were important, while base composition was only minimally influential. PS-ONs bound avidly to PrP-sen but could be displaced by sulfated glycan PrP-res inhibitors, indicating the presence of overlapping binding sites. Labeled PS-ONs also bound to PrP-sen on live cells and were internalized. This binding likely accounts for the antiscrapie activity. Prophylactic PS-ON treatments more than tripled scrapie survival periods in mice. Survival times also increased when PS-ONs were mixed with scrapie brain inoculum. With these antiscrapie activities and their much lower anticoagulant activities than that of pentosan polysulfate, degenerate PS-ONs are attractive new compounds for the treatment of TSEs. PMID:16495266

  13. Potent antiscrapie activities of degenerate phosphorothioate oligonucleotides.

    PubMed

    Kocisko, David A; Vaillant, Andrew; Lee, Kil Sun; Arnold, Kevin M; Bertholet, Nadine; Race, Richard E; Olsen, Emily A; Juteau, Jean-Marc; Caughey, Byron

    2006-03-01

    Although transmissible spongiform encephalopathies (TSEs) are incurable, a key therapeutic approach is prevention of conversion of the normal, protease-sensitive form of prion protein (PrP-sen) to the disease-specific protease-resistant form of prion protein (PrP-res). Here degenerate phosphorothioate oligonucleotides (PS-ONs) are introduced as low-nM PrP-res conversion inhibitors with strong antiscrapie activities in vivo. Comparisons of various PS-ON analogs indicated that hydrophobicity and size were important, while base composition was only minimally influential. PS-ONs bound avidly to PrP-sen but could be displaced by sulfated glycan PrP-res inhibitors, indicating the presence of overlapping binding sites. Labeled PS-ONs also bound to PrP-sen on live cells and were internalized. This binding likely accounts for the antiscrapie activity. Prophylactic PS-ON treatments more than tripled scrapie survival periods in mice. Survival times also increased when PS-ONs were mixed with scrapie brain inoculum. With these antiscrapie activities and their much lower anticoagulant activities than that of pentosan polysulfate, degenerate PS-ONs are attractive new compounds for the treatment of TSEs. PMID:16495266

  14. Disproportionate minority contact.

    PubMed

    Piquero, Alex R

    2008-01-01

    For many years, notes Alex Piquero, youth of color have been overrepresented at every stage of the U.S. juvenile justice system. As with racial disparities in a wide variety of social indicators, the causes of these disparities are not immediately apparent. Some analysts attribute the disparities to "differential involvement"--that is, to differences in offending by minorities and whites. Others attribute them to "differential selection"--that is, to the fact that the justice system treats minority and white offenders in different ways. Still others believe the explanation lies in a combination of the two. Differential involvement may be important earlier in the judicial process, especially in youths' contacts with police, and may influence differential selection later as individuals make their way through the juvenile justice system. Adjudicating between these options, says Piquero, is difficult and may even be impossible. Asking how much minority overrepresentation is due to differences in offending and how much to differences in processing no longer seems a helpful way to frame the discussion. Piquero urges future research to move beyond the debate over "which one matters more" and seek to understand how each of the two hypotheses can explain both the fact of minority overrepresentation in the juvenile justice system and how best to address it. Piquero cites many sizable gaps in the research and policy-relevant literature. Work is needed especially, he says, in analyzing the first stage of the justice system that juveniles confront: police contacts. The police are a critical part of the juvenile justice decision-making system and are afforded far more discretion than any other formal agent of social control, but researchers have paid surprisingly little attention to contacts between police and citizens, especially juveniles. Piquero notes that some states and localities are undertaking initiatives to reduce racial and ethnic disparities. He urges researchers and policymakers to evaluate such initiatives, especially those using strategies with a track record of success. Researchers should also examine empirically the far-reaching consequences of disproportionate minority representation in the juvenile justice system, such as poor outcomes in education, labor force participation, and family formation. Finally, Piquero emphasizes that one critical research area involves updating justice system data systems and repositories, which have failed to track changes in U.S. demographic and immigration patterns. PMID:21337998

  15. Streptococcus pyogenes triggers activation of the human contact system by streptokinase.

    PubMed

    Nitzsche, Ramona; Rosenheinrich, Maik; Kreikemeyer, Bernd; Oehmcke-Hecht, Sonja

    2015-08-01

    Severe invasive infectious diseases remain a major and life-threatening health problem. In serious cases, a systemic activation of the coagulation cascade is a critical complication that is associated with high mortality rates. We report here that streptokinase, a group A streptococcal plasminogen activator, triggers the activation of the human contact system. Activation of contact system factors at the surface of the Streptococcus pyogenes serotype M49 is dependent on streptokinase and plasminogen. Our results also show that secreted streptokinase is an efficient contact system activator, independent from a contact surface. This results in the processing of high-molecular-weight kininogen and the release of bradykinin, a potent vascular mediator. We further investigated whether the ability of 50 different clinical S. pyogenes isolates to activate the contact system is associated with an invasive phenotype. The data reveal that isolates from invasive infections trigger an activation of the contact system more potently than strains isolated from noninvasive infections. The present study gives new insights into the mechanisms by which S. pyogenes triggers the human contact system and stresses the function of soluble and surface located plasmin exploited as a group A streptococcal virulence factor through the action of streptokinase. PMID:25987706

  16. Streptococcus pyogenes Triggers Activation of the Human Contact System by Streptokinase

    PubMed Central

    Nitzsche, Ramona; Rosenheinrich, Maik; Kreikemeyer, Bernd

    2015-01-01

    Severe invasive infectious diseases remain a major and life-threatening health problem. In serious cases, a systemic activation of the coagulation cascade is a critical complication that is associated with high mortality rates. We report here that streptokinase, a group A streptococcal plasminogen activator, triggers the activation of the human contact system. Activation of contact system factors at the surface of the Streptococcus pyogenes serotype M49 is dependent on streptokinase and plasminogen. Our results also show that secreted streptokinase is an efficient contact system activator, independent from a contact surface. This results in the processing of high-molecular-weight kininogen and the release of bradykinin, a potent vascular mediator. We further investigated whether the ability of 50 different clinical S. pyogenes isolates to activate the contact system is associated with an invasive phenotype. The data reveal that isolates from invasive infections trigger an activation of the contact system more potently than strains isolated from noninvasive infections. The present study gives new insights into the mechanisms by which S. pyogenes triggers the human contact system and stresses the function of soluble and surface located plasmin exploited as a group A streptococcal virulence factor through the action of streptokinase. PMID:25987706

  17. Contact sensing from force measurements

    NASA Technical Reports Server (NTRS)

    Bicchi, Antonio; Salisbury, J. K.; Brock, David L.

    1993-01-01

    This article addresses contact sensing (i.e., the problem of resolving the location of a contact, the force at the interface, and the moment about the contact normals). Called 'intrinsic' contact sensing for the use of internal force and torque measurements, this method allows for practical devices that provide simple, relevant contact information in practical robotic applications. Such sensors have been used in conjunction with robot hands to identify objects, determine surface friction, detect slip, augment grasp stability, measure object mass, probe surfaces, and control collision and for a variety of other useful tasks. This article describes the theoretical basis for their operation and provides a framework for future device design.

  18. Contact dermatitis in blacks.

    PubMed

    Berardesca, E; Maibach, H I

    1988-07-01

    Black skin is characterized by structural and functional differences such as increased stratum corneum cohesion, melanin content, and stratum corneum layers. These differences seem to make black skin difficult for irritants and light to penetrate, thus explaining the common opinion that skin in blacks is harder and develops contact dermatitis less frequently. The paucity of interpretable epidemiologic data and of clinical and experimental studies does not permit confirmation of this hypothesis, and the few data available are controversial. This article describes the main physiologic differences between black and white barrier function and reviews the literature on irritation, sensitization, and transcutaneous penetration. We found that the data are still too incomplete to generalize on the resistance, or lack thereof, of black skin (versus white skin) to chemical irritation, sensitization, and penetration. PMID:3048818

  19. Equilibrium contact angle or the most-stable contact angle?

    PubMed

    Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

    2014-04-01

    It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation. PMID:24140073

  20. Point contacts in encapsulated graphene

    SciTech Connect

    Handschin, Clevin; Fülöp, Bálint; Csonka, Szabolcs; Makk, Péter; Blanter, Sofya; Weiss, Markus; Schönenberger, Christian; Watanabe, Kenji; Taniguchi, Takashi

    2015-11-02

    We present a method to establish inner point contacts with dimensions as small as 100 nm on hexagonal boron nitride (hBN) encapsulated graphene heterostructures by pre-patterning the top-hBN in a separate step prior to dry-stacking. 2- and 4-terminal field effect measurements between different lead combinations are in qualitative agreement with an electrostatic model assuming point-like contacts. The measured contact resistances are 0.5–1.5 kΩ per contact, which is quite low for such small contacts. By applying a perpendicular magnetic field, an insulating behaviour in the quantum Hall regime was observed, as expected for inner contacts. The fabricated contacts are compatible with high mobility graphene structures and open up the field for the realization of several electron optical proposals.

  1. Point contacts in encapsulated graphene

    NASA Astrophysics Data System (ADS)

    Handschin, Clevin; Flp, Blint; Makk, Pter; Blanter, Sofya; Weiss, Markus; Watanabe, Kenji; Taniguchi, Takashi; Csonka, Szabolcs; Schnenberger, Christian

    2015-11-01

    We present a method to establish inner point contacts with dimensions as small as 100 nm on hexagonal boron nitride (hBN) encapsulated graphene heterostructures by pre-patterning the top-hBN in a separate step prior to dry-stacking. 2- and 4-terminal field effect measurements between different lead combinations are in qualitative agreement with an electrostatic model assuming point-like contacts. The measured contact resistances are 0.5-1.5 k? per contact, which is quite low for such small contacts. By applying a perpendicular magnetic field, an insulating behaviour in the quantum Hall regime was observed, as expected for inner contacts. The fabricated contacts are compatible with high mobility graphene structures and open up the field for the realization of several electron optical proposals.

  2. A Prototype Antifungal Contact Lens

    PubMed Central

    Ciolino, Joseph B.; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.

    2011-01-01

    Purpose. To design a contact lens to treat and prevent fungal ocular infections. Methods. Curved contact lenses were created by encapsulating econazole-impregnated poly(lactic-co-glycolic) acid (PLGA) films in poly(hydroxyethyl methacrylate) (pHEMA) by ultraviolet photopolymerization. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. The contact lenses and their release media were tested in an antifungal assay against Candida albicans. Cross sections of the pre- and postrelease contact lenses were characterized by scanning electron microscopy and by Raman spectroscopy. Results. Econazole-eluting contact lenses provided extended antifungal activity against Candida albicans fungi. Fungicidal activity varied in duration and effectiveness depending on the mass of the econazole-PLGA film encapsulated in the contact lens. Conclusions. An econazole-eluting contact lens could be used as a treatment for fungal ocular infections. PMID:21527380

  3. Solar cell with improved electrical contacts

    SciTech Connect

    Cavicchi, B.T.; Dill, H.G.; Zemmrich, D.K.

    1987-10-06

    A solar cell is described comprising: a first layer of semiconductor material of a first conductivity type; a second layer of semiconductor material of a second opposite conductivity type disposed on the first layer forming a semiconductor junction therebetween. The first and second layers having first and second major essentially parallel surfaces, respectively, essentially parallel to the semiconductor junction; a layer of aluminum gallium arsenide semiconductor material of the second conductivity type disposed on the second major surface and having an exposed front major surface essentially parallel to the second major surface and further having grooves extending vertically to the second layer; electrically conductive material filling the grooves and electrically contacting the second layer to form metallic contact lines; a flat conductive bar transversely disposed on the exposed front major surface across the grooves and making electrical contact ot the electrically conductive material in the grooves; an electrically conductive flat strip disposed on the exposed major surface and spaced apart from the conductive bar; and at least one electrically conductive bridge electrically coupling the conductive bar to the contact strip.

  4. Promoter Activation by CII, a Potent Transcriptional Activator from Bacteriophage 186*

    PubMed Central

    Murchland, Iain; Ahlgren-Berg, Alexandra; Priest, David G.; Dodd, Ian B.; Shearwin, Keith E.

    2014-01-01

    The lysogeny promoting protein CII from bacteriophage 186 is a potent transcriptional activator, capable of mediating at least a 400-fold increase in transcription over basal activity. Despite being functionally similar to its counterpart in phage λ, it shows no homology at the level of protein sequence and does not belong to any known family of transcriptional activators. It also has the unusual property of binding DNA half-sites that are separated by 20 base pairs, center to center. Here we investigate the structural and functional properties of CII using a combination of genetics, in vitro assays, and mutational analysis. We find that 186 CII possesses two functional domains, with an independent activation epitope in each. 186 CII owes its potent activity to activation mechanisms that are dependent on both the σ70 and α C-terminal domain (αCTD) components of RNA polymerase, contacting different functional domains. We also present evidence that like λ CII, 186 CII is proteolytically degraded in vivo, but unlike λ CII, 186 CII proteolysis results in a specific, transcriptionally inactive, degradation product with altered self-association properties. PMID:25294872

  5. Creation of Principally New Generation of Switching Technique Elements (Reed Switches) with Nanostructured Contact Surfaces

    NASA Astrophysics Data System (ADS)

    Karabanov, S. M.; Zeltser, I. A.; Maizels, R. M.; Moos, E. N.; Arushanov, K. A.

    2011-04-01

    The cycle of activities of the creation of principally new generation of reed switches with nanostructured contact surfaces was implemented. Experimental justification of the opportunity of reed switches creation with modified contact surface was given (instead of precious metals-based galvanic coating). Principally new technological process of modification of magnetically operated contacts contacting surfaces was developed, based on the usage of the ion-plasma methods of nanolayers and nanostructures forming having specified contact features.

  6. Cucurbitacins-type triterpene with potent activity on mouse embryonic fibroblast from Cucumis prophetarum, cucurbitaceae

    PubMed Central

    Ayyad, Seif-Eldin N.; Abdel-Lateff, Ahmed; Basaif, Salim A.; Shier, Thomas

    2011-01-01

    Background: Higher plants are considered as a well-known source of the potent anticancer metabolites with diversity of chemical structures. For instance, taxol is an amazing diterpene alkaloid had been lunched since 1990. Objective: To isolate the major compounds from the fruit extract of Cucumis prophetarum, Cucurbitaceae, which are mainly responsible for the bioactivities as anticancer. Materials and Methods: Plant material was shady air dried, extracted with equal volume of chloroform/methanol, and fractionated with different adsorbents. The structures of obtained pure compounds were elucidated with different spectroscopic techniques employing 1D (1H and 13C) and 2D (COSY, HMQC and HMBC) NMR (Nuclear Magnetic Resonance Spectrometry) and ESI-MS (Eelectrospray Ionization Mass Spectrometry) spectroscopy. The pure isolates were tested towards human cancer cell lines, mouse embryonic fibroblast (NIH3T3) and virally transformed form (KA3IT). Results: Two cucurbitacins derivatives, dihydocucurbitacin B (1) and cucurbitacin B (2), had been obtained. Compounds 1 and 2 showed (showed potent inhibitory activities toward NIH3T3 and KA31T with IC50 0.2, 0.15, 2.5 and 2.0 ?g/ml, respectively. Conclusion: The naturally cucurbitacin derivatives (dihydocucurbitacin B and cucurbitacin B) showed potent activities towards NIH3T3 and KA31T, could be considered as a lead of discovering a new anticancer natural drug. PMID:22022168

  7. Vacuolin-1 potently and reversibly inhibits autophagosome-lysosome fusion by activating RAB5A

    PubMed Central

    Lu, Yingying; Dong, Shichen; Hao, Baixia; Li, Chang; Zhu, Kaiyuan; Guo, Wenjing; Wang, Qian; Cheung, King-Ho; Wong, Connie WM; Wu, Wu-Tian; Markus, Huss; Yue, Jianbo

    2014-01-01

    Autophagy is a catabolic lysosomal degradation process essential for cellular homeostasis and cell survival. Dysfunctional autophagy has been associated with a wide range of human diseases, e.g., cancer and neurodegenerative diseases. A large number of small molecules that modulate autophagy have been widely used to dissect this process and some of them, e.g., chloroquine (CQ), might be ultimately applied to treat a variety of autophagy-associated human diseases. Here we found that vacuolin-1 potently and reversibly inhibited the fusion between autophagosomes and lysosomes in mammalian cells, thereby inducing the accumulation of autophagosomes. Interestingly, vacuolin-1 was less toxic but at least 10-fold more potent in inhibiting autophagy compared with CQ. Vacuolin-1 treatment also blocked the fusion between endosomes and lysosomes, resulting in a defect in general endosomal-lysosomal degradation. Treatment of cells with vacuolin-1 alkalinized lysosomal pH and decreased lysosomal Ca2+ content. Besides marginally inhibiting vacuolar ATPase activity, vacuolin-1 treatment markedly activated RAB5A GTPase activity. Expression of a dominant negative mutant of RAB5A or RAB5A knockdown significantly inhibited vacuolin-1-induced autophagosome-lysosome fusion blockage, whereas expression of a constitutive active form of RAB5A suppressed autophagosome-lysosome fusion. These data suggest that vacuolin-1 activates RAB5A to block autophagosome-lysosome fusion. Vacuolin-1 and its analogs present a novel class of drug that can potently and reversibly modulate autophagy. PMID:25483964

  8. Wireless Measurement of Contact and Motion Between Contact Surfaces

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

    This method uses a magnetic-field- response contact sensor that is designed to identify surface contact and motion between contact locations. The sensor has three components: (1) a capacitor-inductor circuit with two sets of electrical contact pads, (2) a capacitor with a set of electrical contact pads, and (3) an inductor with a set of electrical contact pads. A unique feature of this sensor is that it is inherently multifunctional. Information can be derived from analyzing such sensor response attributes as amplitude, frequency, and bandwidth. A change in one attribute can be due to a change in a physical property of a system. A change in another attribute can be due to another physical property, which has no relationship to the first one.

  9. Method for forming materials

    DOEpatents

    Tolle, Charles R.; Clark, Denis E.; Smartt, Herschel B.; Miller, Karen S.

    2009-10-06

    A material-forming tool and a method for forming a material are described including a shank portion; a shoulder portion that releasably engages the shank portion; a pin that releasably engages the shoulder portion, wherein the pin defines a passageway; and a source of a material coupled in material flowing relation relative to the pin and wherein the material-forming tool is utilized in methodology that includes providing a first material; providing a second material, and placing the second material into contact with the first material; and locally plastically deforming the first material with the material-forming tool so as mix the first material and second material together to form a resulting material having characteristics different from the respective first and second materials.

  10. Contact dermatitis from a presumed allergy to paraphenylenediamine.

    PubMed

    Hansen, Daniel; Voutsalath, Melissa

    2009-12-01

    Paraphenylenediamine (PPD) is a potent skin allergen found in permanent hair dye and temporary henna tattoo ink. Several cases of adverse skin reactions to PPD have been reported in the literature. Here we present a case involving a patient who acquired a temporary tattoo while vacationing in Mexico and subsequently developed contact dermatitis at the tattoo site. He provided a history of permanent hair dye use in the past with associated cutaneous reaction. Temporary tattoos have become increasingly popular with travelers and as a result so have reports of associated allergic contact dermatitis. Of concern is cross-reaction of PPD to related compounds, severe reactions in younger populations and sequelae including increased sensitization, permanent scarring, and persistent postinflammatory hyperpigmentation. PMID:19958436

  11. Antistiction technique using elastomer contact structure in woven electronic textiles

    NASA Astrophysics Data System (ADS)

    Yamashita, Takahiro; Takamatsu, Seiichi; Miyake, Koji; Itoh, Toshihiro

    2014-01-01

    In this paper, we present an antistiction technique using an elastomer contact structure in woven electronic textiles (e-textiles). A coating of poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) in the form of a solid conductive film on a hemispherical silicone elastomer structure is employed in creating an electrical circuit embedded into the fabric of a woven e-textile, where the contact structure reduces the contact area and capillary force generated by the moisture in air between weft and warp ribbons. Stiction occurs between a weft and a warp without the contact structure under an RH of 80%, and the detachment of the stuck ribbon requires a delamination load of about 0.2 N. On the other hand, in the case of contact between the contact structure and the ribbon coated with plain PEDOT:PSS, stiction does not occur as the relative humidity increases from 20 to 80%.

  12. Hysteresis during contact angles measurement.

    PubMed

    Diaz, M Elena; Fuentes, Javier; Cerro, Ramon L; Savage, Michael D

    2010-03-15

    A theory, based on the presence of an adsorbed film in the vicinity of the triple contact line, provides a molecular interpretation of intrinsic hysteresis during the measurement of static contact angles. Static contact angles are measured by placing a sessile drop on top of a flat solid surface. If the solid surface has not been previously in contact with a vapor phase saturated with the molecules of the liquid phase, the solid surface is free of adsorbed liquid molecules. In the absence of an adsorbed film, molecular forces configure an advancing contact angle larger than the static contact angle. After some time, due to an evaporation/adsorption process, the interface of the drop coexists with an adsorbed film of liquid molecules as part of the equilibrium configuration, denoted as the static contact angle. This equilibrium configuration is metastable because the droplet has a larger vapor pressure than the surrounding flat film. As the drop evaporates, the vapor/liquid interface contracts and the apparent contact line moves towards the center of the drop. During this process, the film left behind is thicker than the adsorbed film and molecular attraction results in a receding contact angle, smaller than the equilibrium contact angle. PMID:20060981

  13. Cationic Cell-Penetrating Peptides Are Potent Furin Inhibitors

    PubMed Central

    Ramos-Molina, Bruno; Lick, Adam N.; Nasrolahi Shirazi, Amir; Oh, Donghoon; Tiwari, Rakesh; El-Sayed, Naglaa Salem; Parang, Keykavous; Lindberg, Iris

    2015-01-01

    Cationic cell-penetrating peptides have been widely used to enhance the intracellular delivery of various types of cargoes, such as drugs and proteins. These reagents are chemically similar to the multi-basic peptides that are known to be potent proprotein convertase inhibitors. Here, we report that both HIV-1 TAT47-57 peptide and the Chariot reagent are micromolar inhibitors of furin activity in vitro. In agreement, HIV-1 TAT47-57 reduced HT1080 cell migration, thought to be mediated by proprotein convertases, by 25%. In addition, cyclic polyarginine peptides containing hydrophobic moieties which have been previously used as transfection reagents also exhibited potent furin inhibition in vitro and also inhibited intracellular convertases. Our finding that cationic cell-penetrating peptides exert potent effects on cellular convertase activity should be taken into account when biological effects are assessed. PMID:26110264

  14. Contact Mechanisms and Contact Resistance Characteristics of Solid Tin and Plated Tin Contacts Used for Connectors

    NASA Astrophysics Data System (ADS)

    Tamai, Terutaka; Sawada, Shigeru; Hattori, Yasuhiro

    Tin and its alloys have been applied for the plating of electrical contacts for low electrical power conditions. In particular, tin-plated contacts are widely used as connector contacts in automotive applications and as make-break contacts in keyboard switches. In the relationship between contact resistance (R) and contact load (W) for both solid and plated tin, singularities have been found. Previously established and well known theories on the deformation of contact interfaces cannot explain these singularities. In this study, to clarify these singularities, and to obtain a contact model explaining this phenomenon, contact traces for contact load were examined by SEM and STM. The obtained microscopic images indicated piling-up at the periphery of the contact area for both solid and plated tin. In this case the contact configuration comprised a platinum probe with a hemispherical tip surface and a flat tin surface for both solid and plated. When the probe was loaded, this tip of the probe sank into the soft tin surface owing to its lower hardness. In case of solid tin, the sinking of the probe surface into the tin surface causes piling-up around the periphery of the contact trace. In this deformation process, since the periphery of the indentation of the indented contact area severely slid against the surface of the platinum probe while applying a contact load, the contact resistance rapidly decreased with load. In this case, the center portion of the true contact area was not affected mechanically; thus, the surface film on the bottom portion of the deformed of the flat surface did not break down mechanically. On the other hand, in the case of a tin plated surface, similar piling up occurred; however, it was accompanied by scattering and separation of tin crystal grains from the surface. As a result of this process, a decrease in contact resistance similar to that for the solid tin occurred. Since the piling-up of the contact surface is a very important process in the application of connectors, the above-mentioned unusual characteristics were clarified in this study.

  15. [Vital contact with reality].

    PubMed

    Ravagnan, L M

    1976-12-01

    From the standpoint of existential phenomenology, the contact with reality lies in the very phocus of theory, being closely related to another basic conception: that of being-in-the-world. In order to ratify those conceptions, the author reviews some concepts imported from Kurt Lewin's Field Theory, among which: a) vital psychological space, embedding the subject and in close interchange with him; b) intrapsychic regions, having, to a certain extent, autonomous functions, but being related to each other and integrated into the higher unity of the subject. As both systems are interdependent, any modification of the equilibrium of one of them reverberates into the other's, and changes the general conditions of both of them. Reviewing, at the same time, Minkowski's views on schizophrenia, the author sets forth the production of an inner world that becomes autonomous and possesses a degree of reality that overwhelms the true outer world. There is not only the splitting from reality, but the creation of a whole fantastic field, in which the individual participates with all his vital availability. Both views lead to a similar contention: that in some pathological states, the primal link man-real world, is replaced by a new inner correspondence, focused on the imaginary and having effects similar to those of the real world. PMID:1015337

  16. Electroless copper contacts for low concentration silicon solar cells

    NASA Astrophysics Data System (ADS)

    Janušonis, Julius; Galdikas, Algirdas; Juzumas, Valdemaras; JaraminÄ--, Lina; Lukštaraupis, Tomas; Andrijauskas, Darius; JanušonienÄ--, Vida; Janušonis, Darius; Ulbikas, Juras

    2012-10-01

    The purpose of this work was to form highly conductive and low cost copper contacts on shallow and hence optically thin p-n junctions (<0.4μm deep) on a randomly textured solar cells for low concentration PV (LCPV) module. At first, window formation process in SiNx by femtosecond UV laser pulse ablation on the textured surface was introduced. Then nickel silicide contacts were formed and subsequent contact thickening was performed by electroless copper plating in an industrially feasible way. Characteristics of finished solar cells were investigated in this work. The cells were successfully implemented into the low concentration (C=15x) PV module.

  17. Novel indole sulfides as potent HIV-1 NNRTIs.

    PubMed

    Brigg, Siobhan; Pribut, Nicole; Basson, Adriaan E; Avgenikos, Moscos; Venter, Reinhardt; Blackie, Margaret A; van Otterlo, Willem A L; Pelly, Stephen C

    2016-03-15

    In a previous communication we described a series of indole based NNRTIs which were potent inhibitors of HIV replication, both for the wild type and K103N strains of the virus. However, the methyl ether functionality on these compounds, which was crucial for potency, was susceptible to acid promoted indole assisted SN1 substitution. This particular problem did not bode well for an orally bioavailable drug. Here we describe bioisosteric replacement of this problematic functional group, leading to a series of compounds which are potent inhibitors of HIV replication, and are acid stable. PMID:26876929

  18. A new potent immunosuppressive isoflavanonol from Campylotropis hirtella.

    PubMed

    Xuan, Bixia; Du, Xing; Li, Xiaoping; Shen, Zhengwu

    2016-06-01

    Four new flavonoids were isolated from Campylotropis hirtella and these are a chromone and a 2H-chromene, an isoflavone and an isoflavanonol. The structures of these compounds were elucidated by extensive spectroscopic measurements. All of the compounds were assessed for immunosuppressive activity. Compound 4 showed very strong T lymphocyte suppression activity (IC50: 0.13 μM) and potent B lymphocyte suppression activity (IC50: 0.26 μM). Due to its potent immunosuppressive activity and lower cytotoxicity, further structure-activity studies will be pursued on this compound. PMID:26221996

  19. Design, synthesis and biological evaluation of potent FAAH inhibitors.

    PubMed

    Tuo, Wei; Leleu-Chavain, Natascha; Barczyk, Amélie; Renault, Nicolas; Lemaire, Lucas; Chavatte, Philippe; Millet, Régis

    2016-06-01

    A new series of 3-carboxamido-5-aryl-isoxazoles was designed, synthesized and evaluated for their biological activity. Different pharmacomodulations have been explored and the lipophilicity of these compounds was assessed. Investigation of the in vitro biological activity led to the identification of 5 compounds as potent FAAH inhibitors, their good FAAH inhibition capacity is probably correlated with their suitable lipophilicity. Specifically, compound 25 showed similar inhibition potency against FAAH in comparison with URB597, one of the most potent FAAH inhibitor known to date. PMID:27117424

  20. FORMING PROTECTIVE FILMS ON METAL

    DOEpatents

    Gurinsky, D.H.; Kammerer, O.F.; Sadofsky, J.; Weeks, J.R.

    1958-12-16

    Methods are described of inhibiting the corrosion of ferrous metal by contact with heavy liquid metals such as bismuth and gallium at temperatures above 500 icient laborato C generally by bringing nltrogen and either the metal zirconium, hafnium, or titanium into reactlve contact with the ferrous metal to form a thin adherent layer of the nitride of the metal and thereafter maintaining a fractional percentage of the metal absorbed in the heavy liquid metal in contact with the ferrous metal container. The general purpose for uslng such high boiling liquid metals in ferrous contalners would be as heat transfer agents in liquid-metal-fueled nuclear reactors.

  1. Point contact silicon solar cells

    NASA Technical Reports Server (NTRS)

    Swanson, Richard M.

    1987-01-01

    A new type of silicon solar cell has been developed. It is called the point-contact cell because the metal semiconductor contacts are restricted to an array of small points on the back of the cell. The point contact cell has recently demonstrated 22 percent conversion efficiency at one sun and 27.5 percent at 100 suns under an AM1.5 spectrum.

  2. Contact lenses and corneal shields.

    PubMed

    Lang, G E

    1992-08-01

    Contact lenses are widely used all over the world. If fitted and handled properly, contact lenses can be good cosmetic and therapeutic tools. In this review, the different indications for contact lens wear are discussed. Contact lenses can also lead to serious problems. Tear film and morphologic alterations of the cornea, as well as corneal infections of microbial origin, are reviewed. Collagen bandage lenses have been used for some time in the treatment of corneal epithelial defects. Currently, these lenses are being tested as drug delivery systems, especially for use with poorly penetrating drugs, in serious infections of the cornea. PMID:10147733

  3. Mitigation of epidemics in contact networks through optimal contact adaptation *

    PubMed Central

    Youssef, Mina; Scoglio, Caterina

    2013-01-01

    This paper presents an optimal control problem formulation to minimize the total number of infection cases during the spread of susceptible-infected-recovered SIR epidemics in contact networks. In the new approach, contact weighted are reduced among nodes and a global minimum contact level is preserved in the network. In addition, the infection cost and the cost associated with the contact reduction are linearly combined in a single objective function. Hence, the optimal control formulation addresses the tradeoff between minimization of total infection cases and minimization of contact weights reduction. Using Pontryagin theorem, the obtained solution is a unique candidate representing the dynamical weighted contact network. To find the near-optimal solution in a decentralized way, we propose two heuristics based on Bang-Bang control function and on a piecewise nonlinear control function, respectively. We perform extensive simulations to evaluate the two heuristics on different networks. Our results show that the piecewise nonlinear control function outperforms the well-known Bang-Bang control function in minimizing both the total number of infection cases and the reduction of contact weights. Finally, our results show awareness of the infection level at which the mitigation strategies are effectively applied to the contact weights. PMID:23906209

  4. Potent Antibody Protection against an Emerging Alphavirus Threat.

    PubMed

    Kielian, Margaret; Saphire, Erica Ollmann

    2015-11-19

    Chikungunya virus recently caused large outbreaks world-wide. In this issue of Cell, Fox et al. describe several potently neutralizing antibodies against multiple alphaviruses. The structure of the virus in complex with one of the antibodies reveals the antibody-induced rearrangement and crosslinking of the viral surface proteins that result in neutralization. PMID:26590413

  5. Potent Antioxidant Dendrimers Lacking Pro-oxidant Activity

    PubMed Central

    Lee, Choon Young; Sharma, Ajit; Uzarski, Rebecca L.; Cheong, Jae Eun; Xu, Hao; Held, Rich A.; Upadhaya, Samik K.; Nelson, Julie L.

    2010-01-01

    It is well known that antioxidants have protective effects against oxidative stress. Unfortunately, in the presence of transition metals, antioxidants including polyphenols with potent antioxidant activities may also exhibit pro-oxidant effects, which may irreversibly damage DNA. Therefore, antioxidants with strong free radical scavenging abilities and devoid of pro-oxidant effects would be of immense biological importance. We report two antioxidant dendrimers with a surface rich in multiple phenolic hydroxyl groups, benzylic hydrogens and electron donating ring substituents that contribute to their potent free radical quenching property. In order to minimize their pro-oxidant effects, the dendrimers were designed with a metal chelating tris(2-aminoethyl)amine (TREN) core. The dendritic antioxidants were prepared by attachment of six syringaldehyde or vanillin molecules to TREN by reductive amination. They exhibited potent radical scavenging properties: 5 times stronger than quercetin and 15 times more potent than Trolox according to the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The antioxidant dendrimers also protected low-density lipoprotein, lysozyme and DNA against 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced free radical damage. More importantly, unlike quercetin and Trolox, the two TREN antioxidant dendrimers did not damage DNA via their pro-oxidant effects when incubated with physiological amounts of copper ions. The dendrimers also showed no cytotoxicity towards Chinese hamster ovary cells. PMID:20977937

  6. Potent pyrrolidine- and piperidine-based BACE-1 inhibitors

    SciTech Connect

    Iserloh, U.; Wu, Y.; Cumming, J.N.; Pan, J.; Wang, L.Y.; Stamford, A.W.; Kennedy, M.E.; Kuvelkar, R.; Chen, X.; Parker, E.M.; Strickland, C.; Voigt, J.

    2008-08-18

    Based on lead compound 1 identified from the patent literature, we developed novel patentable BACE-1 inhibitors by introducing a cyclic amine scaffold. Extensive SAR studies on both pyrrolidines and piperidines ultimately led to inhibitor 2f, one of the most potent inhibitors synthesized to date. The discovery and development of novel BACE-1 inhibitors incorporating a cyclic amine scaffold is described.

  7. Potent antioxidant dendrimers lacking pro-oxidant activity.

    PubMed

    Lee, Choon Young; Sharma, Ajit; Uzarski, Rebecca L; Cheong, Jae Eun; Xu, Hao; Held, Rich A; Upadhaya, Samik K; Nelson, Julie L

    2011-04-15

    It is well known that antioxidants have protective effects against oxidative stress. Unfortunately, in the presence of transition metals, antioxidants, including polyphenols with potent antioxidant activities, may also exhibit pro-oxidant effects, which may irreversibly damage DNA. Therefore, antioxidants with strong free radical-scavenging abilities and devoid of pro-oxidant effects would be of immense biological importance. We report two antioxidant dendrimers with a surface rich in multiple phenolic hydroxyl groups, benzylic hydrogens, and electron-donating ring substituents that contribute to their potent free radical-quenching properties. To minimize their pro-oxidant effects, the dendrimers were designed with a metal-chelating tris(2-aminoethyl)amine (TREN) core. The dendritic antioxidants were prepared by attachment of six syringaldehyde or vanillin molecules to TREN by reductive amination. They exhibited potent radical-scavenging properties: 5 times stronger than quercetin and 15 times more potent than Trolox according to the 1,1-diphenyl-2-picrylhydrazyl assay. The antioxidant dendrimers also protected low-density lipoprotein, lysozyme, and DNA against 2,2'-azobis(2-amidinopropane) dihydrochloride-induced free radical damage. More importantly, unlike quercetin and Trolox, the two TREN antioxidant dendrimers did not damage DNA via their pro-oxidant effects when incubated with physiological amounts of copper ions. The dendrimers also showed no cytotoxicity toward Chinese hamster ovary cells. PMID:20977937

  8. Trichosanthin, a potent HIV-1 inhibitor, can cleave supercoiled DNA in vitro.

    PubMed Central

    Li, M X; Yeung, H W; Pan, L P; Chan, S I

    1991-01-01

    Trichosanthin, an abortifacient, immunosuppressive and anti-tumor protein purified from the traditional Chinese herb medicine Tian Hua Fen, is a potent inhibitor against HIV-1 replication. Under normal enzymatic digestion conditions, trichosanthin cleaves the supercoiled double-stranded DNA to produce nicked circular and linear DNA. Trichosanthin has no effect on linear double-stranded DNA. Neither does it convert relaxed circular duplex DNA into a supercoiled form in the presence of ATP. Thus trichosanthin is not a DNA gyrase. However, trichosanthin can cleave the relaxed circular DNA into a linear form, indicating that both the circular as well as the supercoiled forms are essential for trichosanthin recognition. In addition, trichosanthin contains one calcium metal ion per protein molecule, which presumably is related to its endonucleolytic activity. Images PMID:1659689

  9. Predictive models for moving contact line flows

    NASA Technical Reports Server (NTRS)

    Rame, Enrique; Garoff, Stephen

    2003-01-01

    Modeling flows with moving contact lines poses the formidable challenge that the usual assumptions of Newtonian fluid and no-slip condition give rise to a well-known singularity. This singularity prevents one from satisfying the contact angle condition to compute the shape of the fluid-fluid interface, a crucial calculation without which design parameters such as the pressure drop needed to move an immiscible 2-fluid system through a solid matrix cannot be evaluated. Some progress has been made for low Capillary number spreading flows. Combining experimental measurements of fluid-fluid interfaces very near the moving contact line with an analytical expression for the interface shape, we can determine a parameter that forms a boundary condition for the macroscopic interface shape when Ca much les than l. This parameter, which plays the role of an "apparent" or macroscopic dynamic contact angle, is shown by the theory to depend on the system geometry through the macroscopic length scale. This theoretically established dependence on geometry allows this parameter to be "transferable" from the geometry of the measurement to any other geometry involving the same material system. Unfortunately this prediction of the theory cannot be tested on Earth.

  10. Seal for fluid forming tools

    DOEpatents

    Golovashchenko, Sergey Fedorovich; Bonnen, John Joseph Francis

    2012-03-20

    An electro-hydraulic forming tool for forming a sheet metal blank in a one-sided die has first and second rigid rings that engage opposite sides of a sheet metal blank. The rigid rings are contained within slots on a die portion and a hydraulic force applicator portion of the forming tool. The seals are either resiliently biased by an elastomeric member or inherently resiliently biased into contact with the blank.

  11. Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

    NASA Astrophysics Data System (ADS)

    Yang, Chunyan; Persson, Bo

    2008-03-01

    We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load [1-4]. For high load the contact area approaches to the nominal contact area (i.e., complete contact), and the interfacial separation approaches to zero. The present results may be very important for soft solids, e.g., rubber, or for very smooth surfaces, where complete contact can be reached at moderate high loads without plastic deformation of the solids. References: [1] C. Yang and B.N.J. Persson, arXiv:0710.0276, (to appear in Phys. Rev. Lett.) [2] B.N.J. Persson, Phys. Rev. Lett. 99, 125502 (2007) [3] L. Pei, S. Hyun, J.F. Molinari and M.O. Robbins, J. Mech. Phys. Sol. 53, 2385 (2005) [4] M. Benz, K.J. Rosenberg, E.J. Kramer and J.N. Israelachvili, J. Phy. Chem. B.110, 11884 (2006)

  12. Discovery of Novel Pyrazole Derivatives as Potent Neuraminidase Inhibitors against Influenza H1N1 Virus.

    PubMed

    Meng, Fan-Jie; Sun, Tao; Dong, Wen-Zhen; Li, Ming-Hong; Tuo, Zhong-Zhen

    2016-03-01

    Ten pyrazole derivatives were synthesized and evaluated for their ability to inhibit the replication of influenza virions. All the compounds were synthesized in good-to-excellent yield, and the structures were ascertained with the help of (1) H NMR, (13) C NMR, mass, and elemental analysis. Among the tested series, compound 4i was identified as the most potent analog against the H1N1 virus, with IC50  = 5.4 µM, while the rest of the compounds showed mild-to-moderate inhibition of infection. Moreover, these compounds showed excellent inhibitory activity against influenza A neuraminidase (NA), with IC50 values ranging from 2.15 to 7.54 µM, among which compound 4i showed the most prominent inhibition with IC50  = 1.32 µM. To further exemplify the molecular contacts with NA, a molecular docking study of 4i was conducted with the 3D crystal structure of enzyme H5N1-NA in complex. Results showed that target molecules interact in a similar fashion with oseltamivir and zanamivir by creating interatomic contacts with Trp178, Glu227, and Arg371. Moreover, in the toxicity assay with the porcine renal proximal cell line, LLC-PK1, the confocal images showed no appreciable change in morphological character at the highest tested dose. PMID:26797880

  13. Superhydrophobic polyethylcyanoacrylate coatings. Contact area with water measured by Raman spectral images, contact angle and Cassie-Baxter model.

    PubMed

    Bonugli, L O; dos Santos, M V Puydinger; de Souza, E F; Teschke, O

    2012-12-15

    Apolar fibers wired into a mesh-like microstructure forming a coating with a contact angle larger than 160° and fabricated by polycyanoacrylate polymerization are described. Interconnected fibers with diameters measuring approximately 5 μm are formed by texturized linear or folded nanowires. The structure forming the deposited film occupies ~1.5% of the coating's top geometric area. This value agrees with the water/coating contact area given by the Cassie-Baxter contact-angle model (~1.5%). The spatial distribution of the surface in contact with water was determined by Raman spectral imaging (~1.5%) using the polycyanoacrylate lines and by scanning electron microscopy (~2.0%). PMID:23021705

  14. CHARACTERIZING HUMAN CONTACT WITH SEDIMENT

    EPA Science Inventory

    People contact sediment during a variety of activities such as fishing, wading and boating. A number of default assumptions are used today to characterize dermal contact with sediments in terms of magnitude, frequency and duration. The accuracy of these default values are widel...

  15. Contact sensitization in the elderly.

    PubMed

    Balato, Anna; Balato, Nicola; Di Costanzo, Luisa; Ayala, Fabio

    2011-01-01

    Contact dermatitis from irritant and allergic sources is the reason for 6% to 10% of all dermatologic visits with considerable morbidity and economic impact. Allergic contact dermatitis is a T-cell-mediated inflammatory reaction and develops in predisposed individuals as a consequence of environmental exposure to allergens. Aging is correlated with the rate and type of contact sensitization because of "immunosenescence." The number of old people is growing around the world. This contribution reviews the main findings from published epidemiologic studies on contact allergy in elderly populations. In all examined studies, patch testing was performed in patients with cutaneous manifestations possibly related to contact dermatitis; the prevalence of contact dermatitis in the elderly was from 33% to 64%. Establishing the most frequent allergens responsible for allergic contact dermatitis in the elderly is a hard task. The commonest allergens reported were nickel sulfate, fragrance mix, diamino diphenylmethane, lanolin alcohols, paraben mix, Euxyl K400, quinoline mix, and balsam of Peru. We emphasize that allergens surveillance is needed to realize an "elderly series" for having a useful adjunct to contact allergy that may help the treatment of each patient. PMID:21146728

  16. Contact modeling for robotics applications

    SciTech Connect

    Lafarge, R.A.; Lewis, C.

    1998-08-01

    At Sandia National Laboratories (SNL), the authors are developing the ability to accurately predict motions for arbitrary numbers of bodies of arbitrary shapes experiencing multiple applied forces and intermittent contacts. In particular, the authors are concerned with the simulation of systems such as part feeders or mobile robots operating in realistic environments. Preliminary investigation of commercial dynamics software packages led them to the conclusion that they could use commercial software to provide everything they needed except for the contact model. They found that ADAMS best fit their needs for a simulation package. To simulate intermittent contacts, they need collision detection software that can efficiently compute the distances between non-convex objects and return the associated witness features. They also require a computationally efficient contact model for rapid simulation of impact, sustained contact under load, and transition to and from contact conditions. This paper provides a technical review of a custom hierarchical distance computation engine developed at Sandia, called the C-Space Toolkit (CSTk). In addition, they describe an efficient contact model using a non-linear damping term developed by SNL and Ohio State. Both the CSTk and the non-linear damper have been incorporated in a simplified two-body testbed code, which is used to investigate how to correctly model the contact using these two utilities. They have incorporated this model into the ADAMS software using the callable function interface. An example that illustrates the capabilities of the 9.02 release of ADAMS with their extensions is provided.

  17. Increased resistance of contact lens related bacterial biofilms to antimicrobial activity of soft contact lens care solutions

    PubMed Central

    Szczotka-Flynn, Loretta B.; Imamura, Yoshifumi; Chandra, Jyotsna; Yu, Changping; Mukherjee, Pranab K.; Pearlman, Eric; Ghannoum, Mahmoud A.

    2014-01-01

    PURPOSE To determine if clinical and reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus form biofilms on silicone hydrogel contact lenses, and ascertain antimicrobial activities of contact lens care solutions. METHODS Clinical and American Type Culture Collection (ATCC) reference strains of Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus were incubated with lotrafilcon A lenses under conditions that facilitate biofilm formation. Biofilms were quantified by quantitative culturing (colony forming units, CFUs), and gross morphology and architecture were evaluated using scanning electron microscopy (SEM) and confocal microscopy. Susceptibilities of the planktonic and biofilm growth phases of the bacteria to five common multipurpose contact lens care solutions and one hydrogen peroxide care solution were assessed. RESULTS P. aeruginosa, S. marcescens, and S. aureus reference and clinical strains formed biofilms on lotrafilcon A silicone hydrogel contact lenses, as dense networks of cells arranged in multiple layers with visible extracellular matrix. The biofilms were resistant to commonly used biguanide preserved multipurpose care solutions. P. aeruginosa and S. aureus biofilms were susceptible to a hydrogen peroxide and a polyquaternium preserved care solution, whereas S. marcescens biofilm was resistant to a polyquaternium preserved care solution but susceptible to hydrogen peroxide disinfection. In contrast, the planktonic forms were always susceptible. CONCLUSIONS P. aeruginosa, S. marcescens, and S. aureus form biofilms on lotrafilcon A contact lenses, which in contrast to planktonic cells, are resistant to the antimicrobial activity of several soft contact lens care products. PMID:19654521

  18. Three-phase contact line and line tension of electrolyte solutions in contact with charged substrates

    NASA Astrophysics Data System (ADS)

    Ibagon, Ingrid; Bier, Markus; Dietrich, S.

    2016-06-01

    The three-phase contact line formed by the intersection of a liquid–vapor interface of an electrolyte solution with a charged planar substrate is studied in terms of classical density functional theory applied to a lattice model. The influence of the substrate charge density and of the ionic strength of the solution on the intrinsic structure of the three-phase contact line and on the corresponding line tension is analyzed. We find a negative line tension for all values of the surface charge density and of the ionic strength considered. The strength of the line tension decreases upon decreasing the contact angle via varying either the temperature or the substrate charge density.

  19. Three-phase contact line and line tension of electrolyte solutions in contact with charged substrates.

    PubMed

    Ibagon, Ingrid; Bier, Markus; Dietrich, S

    2016-06-22

    The three-phase contact line formed by the intersection of a liquid-vapor interface of an electrolyte solution with a charged planar substrate is studied in terms of classical density functional theory applied to a lattice model. The influence of the substrate charge density and of the ionic strength of the solution on the intrinsic structure of the three-phase contact line and on the corresponding line tension is analyzed. We find a negative line tension for all values of the surface charge density and of the ionic strength considered. The strength of the line tension decreases upon decreasing the contact angle via varying either the temperature or the substrate charge density. PMID:27116050

  20. Modeling contact tracing in outbreaks with application to Ebola.

    PubMed

    Browne, Cameron; Gulbudak, Hayriye; Webb, Glenn

    2015-11-01

    Contact tracing is an important control strategy for containing Ebola epidemics. From a modeling perspective, explicitly incorporating contact tracing with disease dynamics presents challenges, and population level effects of contact tracing are difficult to determine. In this work, we formulate and analyze a mechanistic SEIR type outbreak model which considers the key features of contact tracing, and we characterize the impact of contact tracing on the effective reproduction number, Re, of Ebola. In particular, we determine how relevant epidemiological properties such as incubation period, infectious period and case reporting, along with varying monitoring protocols, affect the efficacy of contact tracing. In the special cases of either perfect monitoring of traced cases or perfect reporting of all cases, we derive simple formulae for the critical proportion of contacts that need to be traced in order to bring the effective reproduction number Re below one. Also, in either case, we show that Re can be expressed completely in terms of observable reported case/tracing quantities, namely Re = k((1-q)/q)+km where k is the number of secondary traced infected contacts per primary untraced reported case, km is the number of secondary traced infected contacts per primary traced reported case and (1-q)/q is the odds that a reported case is not a traced contact. These formulae quantify contact tracing as both an intervention strategy that impacts disease spread and a probe into the current epidemic status at the population level. Data from the West Africa Ebola outbreak is utilized to form real-time estimates of Re, and inform our projections of the impact of contact tracing, and other control measures, on the epidemic trajectory. PMID:26297316

  1. CORRIGENDUM: Multiscale electrical contact resistance in clustered contact distribution Multiscale electrical contact resistance in clustered contact distribution

    NASA Astrophysics Data System (ADS)

    Lee, Sangyoung; Cho, Hyun; Jang, Yong Hoon

    2010-06-01

    The authors wish to explain the similarity between some figures in the above paper (hereafter called the JPD paper) and in their other publication, Lee S, Jang Y H and Kim W 2008 Effects of nanosized contact spots on thermal contact resistance J. Appl. Phys.103 074308 (hereafter called the JAP paper), and to explain the differences between the two papers, which are not explicitly stated in the JPD paper. The main objective of the JAP paper is to calculate the thermal contact resistance of the nanosized contact spots in multiscale contact. During the process of multiscale analysis, the thermal conductivity varies, especially below the phonon mean free path. The JPD paper deals with the electrical contact resistance in the multiscale contact distribution with an assumption of constant electrical resistivity, which is known as a different kind of physics in a larger characteristic length scale. There are similar figures in the JPD paper and the JAP paper: figures 6, 7 and 8 in the JPD paper and figures 3, 4 and 5 in the JAP paper. Two research works were performed on the basis of a specific microcontact distribution. In the JAP paper, the scale of the contact distribution is in the range of the phonon mean free path of Si, which is a very small size of contact distribution. In the JPD paper, the scale of contact distribution is in the continuum scale, which is larger than the phonon mean free path. In addition, due to the characteristics of a fractal surface which repeatedly generates a similar shape of contact distribution in the different length scales, the shape of contact distribution looks similar, but the total sizes of domain in the JPD and JAP figures are different. The projected areas L L of fractal surface of the JAP paper and JPD paper are 10 ?m 10 ?m and 10 mm 10 mm, respectively. The length scale is already stated in the JAP paper, but not in the JPD paper. Thus, we have to state that the figures were adapted from the JAP paper without clear attribution and that credit should be given to the original source of the images. Most significantly, the two most important features of the two works are based on totally different physics and the calculation methods for contact resistance. The text of section 4.3 of the JPD paper should be modified. The left column of page 5 and the first two lines of the right column should be replaced by the following text. The projected area of a self-affine fractal surface is plotted in figure 6. In order to find the microcontact spot distribution from the fractal surface, numerical simulations are applied to the model of multiscale rough surface. Several contact models are constructed according to the resolution of 1/24 to 1/28. Figure 7 shows a typical finite element model in which the rough elastic surface is in contact with a perfectly flat rigid surface. Due to the fine meshes in the contact interface, strong mesh gradations are required. The contact simulation enforcing the impenetrability constraint on the mating surfaces is performed by a commercial finite element package, Abaqus/HKS ([22] of the JPD paper). The resulting microcontact spot distributions for different resolution of the rough surface are obtained in figure 8. As reported by Borri-Brunetto et al ([23] of the JPD paper), the actual contact area decreases and the number of contact spots increases as the resolution of the discretization escalates. A more detailed description for the model can be obtained in the JAP paper.

  2. Producing thin film photovoltaic modules with high integrity interconnects and dual layer contacts

    DOEpatents

    Jansen, Kai W.; Maley, Nagi

    2000-01-01

    High performance photovoltaic modules are produced with improved interconnects by a special process. Advantageously, the photovoltaic modules have a dual layer back (rear) contact and a front contact with at least one layer. The front contact and the inner layer of the back contact can comprise a transparent conductive oxide. The outer layer of the back contact can comprise a metal or metal oxide. The front contact can also have a dielectric layer. In one form, the dual layer back contact comprises a zinc oxide inner layer and an aluminum outer layer and the front contact comprises a tin oxide inner layer and a silicon dioxide dielectric outer layer. One or more amorphous silicon-containing thin film semiconductors can be deposited between the front and back contacts. The contacts can be positioned between a substrate and an optional superstrate. During production, the transparent conductive oxide layer of the front contact is scribed by a laser, then the amorphous silicon-containing semiconductors and inner layer of the dual layer back contact are simultaneously scribed and trenched (drilled) by the laser and the trench is subsequently filled with the same metal as the outer layer of the dual layer back contact to provide a superb mechanical and electrical interconnect between the front contact and the outer layer of the dual layer back contact. The outer layer of the dual layer back contact can then be scribed by the laser. For enhanced environmental protection, the photovoltaic modules can be encapsulated.

  3. Producing thin film photovoltaic modules with high integrity interconnects and dual layer contacts

    DOEpatents

    Jansen, Kai W.; Maley, Nagi

    2001-01-01

    High performance photovoltaic modules are produced with improved interconnects by a special process. Advantageously, the photovoltaic modules have a dual layer back (rear) contact and a front contact with at least one layer. The front contact and the inner layer of the back contact can comprise a transparent conductive oxide. The outer layer of the back contact can comprise a metal or metal oxide. The front contact can also have a dielectric layer. In one form, the dual layer back contact comprises a zinc oxide inner layer and an aluminum outer layer and the front contact comprises a tin oxide inner layer and a silicon dioxide dielectric outer layer. One or more amorphous silicon-containing thin film semiconductors can be deposited between the front and back contacts. The contacts can be positioned between a substrate and an optional superstrate. During production, the transparent conductive oxide layer of the front contact is scribed by a laser, then the amorphous silicon-containing semiconductors and inner layer of the dual layer back contact are simultaneously scribed and trenched (drilled) by the laser and the trench is subsequently filled with the same metal as the outer layer of the dual layer back contact to provide a superb mechanical and electrical interconnect between the front contact and the outer layer of the dual layer back contact. The outer layer of the dual layer back contact can then be scribed by the laser. For enhanced environmental protection, the photovoltaic modules can be encapsulated.

  4. Self Contact Organic Transistors

    NASA Astrophysics Data System (ADS)

    Inoue, Jun-ichi; Wada, Hiroshi; Mori, Takehiko

    2010-07-01

    Thin films of various organic semiconductors, such as pentacene, sexithiophene, copper phthalocyanine, and C60, as well as an organic charge-transfer salt (TTF)(TCNQ) [TTF: tetrathiafulvalene; TCNQ: tetracyanoquinodimethane] are laser-irradiated to form conductive films, which are identified by Raman spectroscopy and atomic force microscopy to be carbon. The resulting practically transparent films are as conductive as laser-sintered carbon films and show temperature-independent conductivity. Source and drain electrodes of organic field-effect transistors are patterned by this method; in these “self-contact” transistors, both the active layers and the electrodes are derived from the same organic film. The laser-sintered carbon films are also utilized for organic single-crystal transistors based on rubrene and TCNQ.

  5. Dancing droplets: Contact angle, drag, and confinement

    NASA Astrophysics Data System (ADS)

    Benusiglio, Adrien; Cira, Nate; Prakash, Manu

    2015-11-01

    When deposited on a clean glass slide, a mixture of water and propylene glycol forms a droplet of given contact angle, when both pure liquids spread. (Cira, Benusiglio, Prakash: Nature, 2015). The droplet is stabilized by a gradient of surface tension due to evaporation that induces a Marangoni flow from the border to the apex of the droplets. The apparent contact angle of the droplets depends on both their composition and the external humidity as captured by simple models. These droplets present remarkable properties such as lack of a large pinning force. We discuss the drag on these droplets as a function of various parameters. We show theoretical and experimental results of how various confinement geometries change the vapor gradient and the dynamics of droplet attraction.

  6. 'Contact' in Space Leads to New Lenses

    NASA Technical Reports Server (NTRS)

    2004-01-01

    While gravity has its advantages in keeping us balanced and grounded here on Earth, scientists often find that they are at a disadvantage when trying to conduct research under its powerful, pulling influence. In these instances, the scientists prefer performing their studies in the weightless atmosphere of microgravity, where gravity is greatly reduced and solids, liquids, and gases behave differently. In 1993, Paragon Vision Sciences, Inc., of Mesa, Arizona, participated in a research project with NASA's Langley Research Center to perfect a process for developing contact lenses. The project called for three experiments that would fly onboard the Space Shuttle over the course of three separate missions, from 1993 to 1996. By unleashing contact lens materials to the microgravity settings of space, scientists from NASA and Paragon hoped to better understand how polymers - large molecules that make up plastics - are formed.

  7. Contact material optimization and contact physics in metal-contact microelectromechanical systems (MEMS) switches

    NASA Astrophysics Data System (ADS)

    Yang, Zhenyin

    Metal-contact MEMS switches hold great promise for implementing agile radio frequency (RF) systems because of their small size, low fabrication cost, low power consumption, wide operational band, excellent isolation and exceptionally low signal insertion loss. Gold is often utilized as a contact material for metal-contact MEMS switches due to its excellent electrical conductivity and corrosion resistance. However contact wear and stiction are the two major failure modes for these switches due to its material softness and high surface adhesion energy. To strengthen the contact material, pure gold was alloyed with other metal elements. We designed and constructed a new micro-contacting test facility that closely mimic the typical MEMS operation and utilized this facility to efficiently evaluate optimized contact materials. Au-Ni binary alloy system as the candidate contact material for MEMS switches was systematically investigated. A correlation between contact material properties (etc. microstructure, micro-hardness, electrical resistivity, topology, surface structures and composition) and micro-contacting performance was established. It was demonstrated nano-scale graded two-phase Au-Ni film could possibly yield an improved device performance. Gold micro-contact degradation mechanisms were also systematically investigated by running the MEMS switching tests under a wide range of test conditions. According to our quantitative failure analysis, field evaporation could be the dominant failure mode for highfield (> critical threshold field) hot switching; transient thermal-assisted wear could be the dominant failure mode for low-field hot switching; on the other hand, pure mechanical wear and steady current heating (1 mA) caused much less contact degradation in cold switching tests. Results from low-force (50 muN/micro-contact), low current (0.1 mA) tests on real MEMS switches indicated that continuous adsorbed films from ambient air could degrade the switch contact resistance. Our work also contributes to the field of general nano-science and technology by resolving the transfer directionality of field evaporation of gold in atomic force microscope (AFM)/scanning tunneling microscope (STM).

  8. Parameters of sexual contact of boys with women.

    PubMed

    Condy, S R; Templer, D I; Brown, R; Veaco, L

    1987-10-01

    The incidence of sexual contact with boys by women was found more prevalent than had been contended in the clinical literature. Male penitentiary inmates reported higher heterosexual contact as children than did college men. The effects upon the boy and his later adult sex life were generally reported as not traumatic, although coercion by the woman tended to be associated with a bad feeling about the experience at the time and a negative effect upon adult sex life. The majority of women were friends, neighbors, baby sitters, and strangers to the boy. Intercourse and genital touching were the predominant forms of sexual activity. Prison women who reported having such contact were significantly higher than the prison women who did not report contact on the Mini-Mult Schizophrenia and Hypomania scales and significantly lower on the Lie scale. Educational levels of the men and their parents were inversely associated with history of sexual contact. PMID:3689106

  9. Au/p-diamond ohmic contacts deposited by RF sputtering

    NASA Astrophysics Data System (ADS)

    Zhen, C. M.; Wang, X. Q.; Wu, X. C.; Liu, C. X.; Hou, D. L.

    2008-12-01

    Ohmic contacts have been formed on diamond films using a monolayer Au. Au film was deposited by radio frequency sputtering. I- V measurements show the good ohmic behavior of the contacts in the as-deposited and annealed states and the specific contact resistivity obtained by circular transmission line model was 1.27 × 10 -3 and 5.43 × 10 -4 Ω cm 2, respectively. Radio frequency sputtering makes an obvious interdiffusion between Au and diamond in the as-deposited contacts. Annealing the contact enhances the interdiffusion. X-ray photoelectron spectroscopy analyses and cross-sectional scan electron microscopy reveal the presence of an intermediate layer at the interface due to the intermixing between Au and diamond. Surface native oxide of the diamond film was effectively removed by treating the substrate film in boiling aqua regia solution.

  10. Dry Eye in Pediatric Contact Lens Wearers

    PubMed Central

    Greiner, Katie L.; Walline, Jeffrey J.

    2015-01-01

    Objectives To determine whether children who wear contact lenses truly have fewer dry eye complaints than adults. Methods Ninety-four pediatric contact lens wearers, ages 8 to 14 years, were recruited and given the Contact Lens Dry Eye Questionnaire (CLDEQ) short form. The survey is designed to diagnose dry eye syndrome by obtaining information on the frequency of dryness and light sensitivity and their corresponding intensity levels within the first two hours of putting in the lenses, in the middle of the day, and at the end of the day. The responses were scored by multiplying the frequency by the average intensity and a constant. A composite score was calculated by subtracting the photophobia score from the dryness score, and the results were compared to adult samples from the literature. The questionnaire also asked whether the subject thought he/she had dry eyes while wearing contact lenses. Subjects that thought they had dry eyes and had a CLDEQ composite score >0.03 were diagnosed with dry eye. Subjects who were unsure if they dry eye or said they did not have dry eye but scored >1.29 were also diagnosed with dry eye. Results The average (± SD) age of the sample was 11.7 ± 1.5 years, 56.4% were female, 59.6% were white, and 19.1% were black. The mean (± SD) CLDEQ composite score was 0.25 ±0.50 (range= -1.20 to 1.45). In the literature, the adult mean (± SD) CLDEQ composite score was 1.02 ±0.80 (range= -0.74 to 4.50). Of the 94 surveys collected, 4.3% of children were categorized with dry eye compared to 56.2% of adults who completed the CLDEQ survey in the adult study. Conclusions Pediatric contact lens wearers have fewer complaints about dry eyes than adult contact lens wearers, which may be due to improved tear film, differences in reporting of symptoms, or modality of contact lens wear. PMID:21060258

  11. 76 FR 33031 - Agency Information Collection (Request for Contact Information) Activity Under OMB Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-07

    ... AFFAIRS Agency Information Collection (Request for Contact Information) Activity Under OMB Review AGENCY... correspondence. FOR FURTHER INFORMATION CONTACT: Denise McLamb, Enterprise Records Service (005R1B), Department... INFORMATION: Title: Request for Contact Information, VA Form 21-30. OMB Control Number: 2900-0660. Type...

  12. Carrier Selective, Passivated Contacts for High Efficiency Silicon Solar Cells based on Transparent Conducting Oxides

    SciTech Connect

    Young, David L.; Nemeth, William; Grover, Sachit; Norman, Andrew; Yuan, Hao-Chih; Lee, Benjamin G.; LaSalvia, Vincenzo; Stradins, Paul

    2014-01-01

    We describe the design, fabrication and results of passivated contacts to n-type silicon utilizing thin SiO2 and transparent conducting oxide layers. High temperature silicon dioxide is grown on both surfaces of an n-type wafer to a thickness <50 Å, followed by deposition of tin-doped indium oxide (ITO) and a patterned metal contacting layer. As deposited, the thin-film stack has a very high J0,contact, and a non-ohmic, high contact resistance. However, after a forming gas anneal, the passivation quality and the contact resistivity improve significantly. The contacts are characterized by measuring the recombination parameter of the contact (J0,contact) and the specific contact resistivity (ρcontact) using a TLM pattern. The best ITO/SiO2 passivated contact in this study has J0,contact = 92.5 fA/cm2 and ρcontact = 11.5 mOhm-cm2. These values are placed in context with other passivating contacts using an analysis that determines the ultimate efficiency and the optimal area fraction for contacts for a given set of (J0,contact, ρcontact) values. The ITO/SiO2 contacts are found to have a higher J0,contact, but a similar ρcontact compared to the best reported passivated contacts.

  13. Status of wraparound contact solar cells and arrays

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.; Young, L. E.

    1978-01-01

    Solar cells with wraparound contacts provide the following advantages in array assembly: (1) eliminate the need for discretely formed, damage susceptible series tabs; (2) eliminate the n gap problem by allowing the use of uniform covers over the entire cell surface; (3) allow a higher packing factor by reducing the additional series spacing formly required for forming, and routing the series tab; and (4) allow the cell bonding to the interconnect system to be a single-side function wherein series contacts can be made at the same time parallel contracts are made.

  14. Contact Pressure and Shear Stress Analysis on Conforming Contact Problem

    NASA Astrophysics Data System (ADS)

    Nagatani, Haruo; Imou, Akitoshi

    Two methods to solve a conforming contact problem are proposed. First method is general and can be applicable to the contact case between elastic arbitrary shape bodies. For verification FEA is performed on the convex-concave sphere contact, and the result of this method is well corresponding to the FEA result. However, the accuracy deteriorates when the mesh aspect ratio is extremely large. This phenomenon is caused by the usage of numerical integration for the calculation of influence coefficient. The second method is devised to avoid this problem, while this improved method is applicable only to the case when the contact area can be considered to be on a cylinder surface. By using this method, the contact pressure can be obtained without the deterioration even in the case of edge load occurring between ball bearing race shoulder and ball. The results of the contact pressure and the shear stress that is necessary for bearing life estimation are compared with the FEA result, which showed well correspondence.

  15. Wraparound-contact solar cells

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.; Klucher, T. M.; Thornhill, J. W.; Scott-Monck, J.

    1979-01-01

    Positive and negative electrical contacts are on back surface of wraparound-contact solar cell. With both terminals on nonilluminated side, cells can be connected back-to-back, and interconnection of many cells can be automated by using printed-circuit techniques. Cells are made by screen-printing layer of dielectric around edge of cell and extending top contact over dielectric to back surface. Wraparound also facilitates application of transparent covers and encapsulants. Efficiencies of cells are in excess of seventeen percent.

  16. Capteur Tridimensionnel Sans Contact

    NASA Astrophysics Data System (ADS)

    Magnant, D.

    1986-07-01

    Three-dimensionnal measurements on human body using a scanning laser beam. The active optical apparatus principle and the image data processing giving three dimensional informations of complex forms is presented. The output is given in terms of one or several files of real coordinates. The basic components of this system are : A light-sheet which is generated by a laser source and, the optical sensors (cameras) with corresponding hard-soft extractor; This 3D sensorial system is especially adapted to partial or total acquisitions of body coordinates. The main advantages are : - Vision and measurement capability of complete accessible contours without shadow areas. - The real time data acquisition and scanning of the object in a few seconds. - The access to distance measurements between significant points. - The presently obtained accuracy is better than 1/1000 in relatives units and lower than one MM absolute. - Physically stuck markers on body are not necessary. - The monochromaticity of the laser light source allows the use of a color filter over the detector (camera) for ambient light rejection. - The fully programmable capability for any use, allows the adaptation to a large variety of particular cases. - The hardware open system offers many options. - The hard-soft tool is designed for auto-calibration operation. - The system offers easy connection to a host computer or a production robot.

  17. SAH derived potent and selective EZH2 inhibitors.

    PubMed

    Kung, Pei-Pei; Huang, Buwen; Zehnder, Luke; Tatlock, John; Bingham, Patrick; Krivacic, Cody; Gajiwala, Ketan; Diehl, Wade; Yu, Xiu; Maegley, Karen A

    2015-04-01

    A series of novel enhancer of zeste homolog 2 (EZH2) inhibitors was designed based on the chemical structure of the histone methyltransferase (HMT) inhibitor SAH (S-adenosyl-l-homocysteine). These nucleoside-based EZH2 inhibitors blocked the methylation of nucleosomes at H3K27 in biochemical assays employing both WT PRC2 complex as well as a Y641N mutant PRC2 complex. The most potent compound, 27, displayed IC50's against both complexes of 270 nM and 70 nM, respectively. To our knowledge, compound 27 is the most potent SAH-derived inhibitor of the EZH2 PRC2 complex yet identified. This compound also displayed improved potency, lipophilic efficiency (LipE), and selectivity profile against other lysine methyltransferases compared with SAH. PMID:25746813

  18. Phosphinic peptides as potent inhibitors of zinc-metalloproteases.

    PubMed

    Georgiadis, Dimitris; Dive, Vincent

    2015-01-01

    The development of transition-state analogs is a major objective in enzymology, not only for developing potent inhibitors of enzymes but also for dissecting enzyme catalytic mechanisms. Phosphinic peptides, which share closed structural similarities with the transition-state of peptide substrate upon hydrolysis, have thus been considered for identifying potent inhibitors of proteases. Focusing on the zinc-proteases family, this review presents the most important synthetic efforts performed to obtain the desired compounds. Crystal structures of the phosphinic peptides in interaction with their zinc-protease targets are reported to illustrate the structural features which may explain the potency of these compounds and how they contribute to uncover key enzyme catalytic residues. Based on a remarkable metabolic stability, phosphinic peptides can be used to probe the in vivo function of zinc-proteases. Progress on chemistry and better understanding on the functional roles of zinc-proteases should allow transferring these compounds from shelf to clinic. PMID:25370521

  19. Identification of potent inhibitors of the chicken soluble epoxide hydrolase.

    PubMed

    Shihadih, Diyala S; Harris, Todd R; Yang, Jun; Merzlikin, Oleg; Lee, Kin Sing S; Hammock, Bruce D; Morisseau, Christophe

    2015-01-15

    In vertebrates, soluble epoxide hydrolase (sEH) hydrolyzes natural epoxy-fatty acids (EpFAs), which are chemical mediators modulating inflammation, pain, and angiogenesis. Chick embryos are used to study angiogenesis, particularly its role in cardiovascular biology and pathology. To find potent and bio-stable inhibitors of the chicken sEH (chxEH) a library of human sEH inhibitors was screened. Derivatives of 1(adamantan-1-yl)-3-(trans-4-phenoxycyclohexyl) urea were found to be very potent tight binding inhibitors (KI <150pM) of chxEH while being relatively stable in chicken liver microsomes, suggesting their usefulness to study the role of EpFAs in chickens. PMID:25479771

  20. 9-Benzoyl 9-deazaguanines as potent xanthine oxidase inhibitors.

    PubMed

    Rodrigues, Marili V N; Barbosa, Alexandre F; da Silva, Júlia F; dos Santos, Deborah A; Vanzolini, Kenia L; de Moraes, Marcela C; Corrêa, Arlene G; Cass, Quezia B

    2016-01-15

    A novel potent xanthine oxidase inhibitor, 3-nitrobenzoyl 9-deazaguanine (LSPN451), was selected from a series of 10 synthetic derivatives. The enzymatic assays were carried out using an on-flow bidimensional liquid chromatography (2D LC) system, which allowed the screening¸ the measurement of the kinetic inhibition constant and the characterization of the inhibition mode. This compound showed a non-competitive inhibition mechanism with more affinity for the enzyme-substrate complex than for the free enzyme, and inhibition constant of 55.1±9.80 nM, about thirty times more potent than allopurinol. Further details of synthesis and enzymatic studies are presented herein. PMID:26712096

  1. Inhibitors of bacterial transcription are compounds for potent antimicrobial drugs.

    PubMed

    Turecka, Katarzyna; Waleron, Krzysztof

    2013-01-01

    The increasing resistance of microorganisms against antibiotics available on the pharmaceutical market is now a global problem. There is an incessant necessity to search for new, effective treatments against resistant strains of microorganisms, for new potent classes of antibiotics with novel modes of action targeted at important components of microbial cells. Such a critical, essential system for cell functioning is a RNA polymerase (RNAP), an enzyme that catalyses one of the stages of gene expression: transcription. RNAP is a proven target for a number of antibiotics, and it still remains an attractive drug target for new potent antimicrobial compounds. In this review several examples of inhibitors for transcription and RNAP are presented. PMID:24809716

  2. Antileishmanial activity of MDL 28170, a potent calpain inhibitor.

    PubMed

    d'Avila-Levy, Claudia M; Marinho, Fernanda A; Santos, Lívia O; Martins, Juliana L; Santos, André L S; Branquinha, Marta H

    2006-08-01

    Several calpain inhibitors are under development and some are useful agents against important human pathogens. We therefore investigated the effect of MDL 28170, a potent calpain inhibitor, on the growth of Leishmania amazonensis. After 48 h of treatment, the inhibitor exhibited a dose-dependent antileishmanial activity, with a 50% lethal dose (LD(50)) of 23.3 microM. The inhibitor promoted cellular alterations, such as the parasites becoming short and round. A calpain-like protein migrating at 80 kDa was identified by Western blotting. In addition, the calpain-like molecules were identified on the cell surface of the flagellate. These results add new in vitro insights into the exploitation of calpain inhibitors in treating parasitic infections and add this family of peptidases to the list of potential targets for development of more potent and specific inhibitors against trypanosomatids. PMID:16842979

  3. Permission Forms

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2005-01-01

    The prevailing practice in public schools is to routinely require permission or release forms for field trips and other activities that pose potential for liability. The legal status of such forms varies, but they are generally considered to be neither rock-solid protection nor legally valueless in terms of immunity. The following case and the…

  4. Bryostatins: potent, new activators of protein kinase C

    SciTech Connect

    Smith, L.; Pettit, G.R.; Smith, J.B.

    1986-03-01

    Bryostatins (B) are a class of 17 macrocyclic lactones that have antineoplastic activity in the murine P388 lymphocytic leukemia system. Bryostatin-1 (B-1) is a potent co-mitogen for the Swiss 3T3 line of murine fibroblasts that have been arrested in G/sub 1//G/sub 0/. B-1 and insulin synergistically increase entry into the S phase of the cell cycle measured autoradiographically as % nuclei labeled with (/sup 3/H)thymidine. A prior treatment of the cells with phorbol 13-myristate 12-acetate (PMA) selectively eliminated the mitogenic response to B-1 or PMA. Conversely, a prior treatment of the cells with B-1 eliminated the mitogenic response to PMA or B-1. Five other B are approximately equipotent to B-1, but B-3 is 5 to 10 times less potent than B-1 as a mitogen. B-1 inhibits the binding of (/sup 3/H)phorbol dibutyrate ((/sup 3/H)PDB) at 4/sup 0/C to a high affinity receptor in the cells. B-3 was also less potent than B-1 as an inhibitor of (/sup 3/H)PDB binding. B-3 differs from B-1 in the diacylglycerol-like component of the molecule. In vitro B-1 and PMA are similarly potent activators of protein kinase C from bovine brain. Further comparisons of the relative activities of the various B are needed to define the structural features that are critical for the activation of protein kinase C which may help in the design of tumor promoter antagonists.

  5. Diversity Against Adversity: How Adaptive Immune System Evolves Potent Antibodies

    NASA Astrophysics Data System (ADS)

    Heo, Muyoung; Zeldovich, Konstantin B.; Shakhnovich, Eugene I.

    2011-07-01

    Adaptive immunity is an amazing mechanism, whereby new protein functions—affinity of antibodies (Immunoglobulins) to new antigens—evolve through mutation and selection in a matter of a few days. Despite numerous experimental studies, the fundamental physical principles underlying immune response are still poorly understood. In considerable departure from past approaches, here, we propose a microscopic multiscale model of adaptive immune response, which consists of three essential players: The host cells, viruses, and B-cells in Germinal Centers (GC). Each moiety carries a genome, which encodes proteins whose stability and interactions are determined from their sequences using laws of Statistical Mechanics, providing an exact relationship between genomic sequences and strength of interactions between pathogens and antibodies and antibodies and host proteins (autoimmunity). We find that evolution of potent antibodies (the process known as Affinity Maturation (AM)) is a delicate balancing act, which has to reconcile the conflicting requirements of protein stability, lack of autoimmunity, and high affinity of antibodies to incoming antigens. This becomes possible only when antibody producing B cells elevate their mutation rates (process known as Somatic Hypermutation (SHM)) to fall into a certain range—not too low to find potency increasing mutations but not too high to destroy stable Immunoglobulins and/or already achieved affinity. Potent antibodies develop through clonal expansion of initial B cells expressing marginally potent antibodies followed by their subsequent affinity maturation through mutation and selection. As a result, in each GC the population of mature potent Immunoglobulins is monoclonal being ancestors of a single cell from initial (germline) pool. We developed a simple analytical theory, which provides further rationale to our findings. The model and theory reveal the molecular factors that determine the efficiency of affinity maturation, thereby providing insight into the variability of the immune response to cytopathic viruses (the direct response by germline antibodies) and poorly cytopathic viruses (a crucial role of SHM in the response).

  6. Synthesis and Potent Antimalarial Activity of Kalihinol B

    PubMed Central

    2016-01-01

    Of the 50+ kalihinane diterpenoids reported to date, only five had been tested for antimalarial activity, in spite of the fact that kalihinol A is the most potent among the members of the larger family of antimalarial isocyanoterpenes. We have validated a strategy designed to access many of the kalihinanes with a 12-step enantioselective synthesis of kalihinol B, the tetrahydrofuran isomer of kalihinol A (a tetrahydropyran). Kalihinol B shows similarly high potency against chloroquine-resistant Plasmodium falciparum. PMID:25815413

  7. Extensive screening for herbal extracts with potent antioxidant properties

    PubMed Central

    Niwano, Yoshimi; Saito, Keita; Yoshizaki, Fumihiko; Kohno, Masahiro; Ozawa, Toshihiko

    2011-01-01

    This paper summarizes our research for herbal extracts with potent antioxidant activity obtained from a large scale screening based on superoxide radical (O2•−) scavenging activity followed by characterization of antioxidant properties. Firstly, scavenging activity against O2•− was extensively screened from ethanol extracts of approximately 1000 kinds of herbs by applying an electron spin resonance (ESR)-spin trapping method, and we chose four edible herbal extracts with prominently potent ability to scavenge O2•−. They are the extracts from Punica granatum (Peel), Syzygium aromaticum (Bud), Mangifera indica (Kernel), and Phyllanthus emblica (Fruit). These extracts were further examined to determine if they also scavenge hydroxyl radical (•OH), by applying the ESR spin-trapping method, and if they have heat resistance as a desirable characteristic feature. Experiments with the Fenton reaction and photolysis of H2O2 induced by UV irradiation demonstrated that all four extracts have potent ability to directly scavenge •OH. Furthermore, the scavenging activities against O2•− and •OH of the extracts of P. granatum (peel), M. indica (kernel) and P. emblica (fruit) proved to be heat-resistant. The results of the review might give useful information when choosing a potent antioxidant as a foodstuff. For instance, the four herbal extracts chosen from extensive screening possess desirable antioxidant properties. In particular, the extracts of the aforementioned three herbs are expected to be suitable for food processing in which thermal devices are used, because of their heat resistance. PMID:21297917

  8. Biaryl analogues of teriflunomide as potent DHODH inhibitors.

    PubMed

    Erra, Montse; Moreno, Imma; Sanahuja, Jordi; Andrs, Miriam; Reinoso, Raquel F; Lozoya, Estrella; Pizcueta, Pilar; Godessart, Nria; Castro-Palomino, Julio Cesar

    2011-12-15

    The structure-activity relationships of a novel series of biaryl dihydroorotate dehydrogenase (DHODH) inhibitors related to teriflunomide are disclosed. These biaryl derivatives were the result of structure-based design and proved to be potent DHODH inhibitors which in addition showed good antiproliferative activities on peripheral blood mononuclear cells and good efficacies in vivo in the rat adjuvant-induced-arthritis model. PMID:22078215

  9. Racial Disparity in Police Contacts

    PubMed Central

    Crutchfield, Robert D.; Haggerty, Kevin P.; McGlynn, Anne; Catalano, Richard F.

    2013-01-01

    Criminologists agree the race disparity in arrests cannot be fully explained by differences in criminal behavior. We examine social environment factors that may lead to racial differences in police contact in early adolescence, including family, peers, school, and community. Data are from 331 8th-grade students. Blacks were almost twice as likely as Whites to report a police contact. Blacks reported more property crime but not more violent crime than Whites. Police contacts were increased by having a parent who had been arrested, a sibling involved in criminal activity, higher observed reward for negative behavior, having school disciplinary actions, and knowing adults who engaged in substance abuse or criminal behavior. Race differences in police contacts were partially attributable to more school discipline. PMID:24363956

  10. The Type III Secretion Translocation Pore Senses Host Cell Contact

    PubMed Central

    Armentrout, Erin I.; Rietsch, Arne

    2016-01-01

    Type III secretion systems (T3SS) are nano-syringes used by a wide range of Gram-negative pathogens to promote infection by directly injecting effector proteins into targeted host cells. Translocation of effectors is triggered by host-cell contact and requires assembly of a pore in the host-cell plasma membrane, which consists of two translocator proteins. Our understanding of the translocation pore, how it is assembled in the host cell membrane and its precise role in effector translocation, is extremely limited. Here we use a genetic technique to identify protein-protein contacts between pore-forming translocator proteins, as well as the T3SS needle-tip, that are critical for translocon function. The data help establish the orientation of the translocator proteins in the host cell membrane. Analysis of translocon function in mutants that break these contacts demonstrates that an interaction between the pore-forming translocator PopD and the needle-tip is required for sensing host cell contact. Moreover, tethering PopD at a dimer interface also specifically prevents host-cell sensing, arguing that the translocation pore is actively involved in detecting host cell contact. The work presented here therefore establishes a signal transduction pathway for sensing host cell contact that is initiated by a conformational change in the translocation pore, and is subsequently transmitted to the base of the apparatus via a specific contact between the pore and the T3SS needle-tip. PMID:27022930

  11. The Type III Secretion Translocation Pore Senses Host Cell Contact.

    PubMed

    Armentrout, Erin I; Rietsch, Arne

    2016-03-01

    Type III secretion systems (T3SS) are nano-syringes used by a wide range of Gram-negative pathogens to promote infection by directly injecting effector proteins into targeted host cells. Translocation of effectors is triggered by host-cell contact and requires assembly of a pore in the host-cell plasma membrane, which consists of two translocator proteins. Our understanding of the translocation pore, how it is assembled in the host cell membrane and its precise role in effector translocation, is extremely limited. Here we use a genetic technique to identify protein-protein contacts between pore-forming translocator proteins, as well as the T3SS needle-tip, that are critical for translocon function. The data help establish the orientation of the translocator proteins in the host cell membrane. Analysis of translocon function in mutants that break these contacts demonstrates that an interaction between the pore-forming translocator PopD and the needle-tip is required for sensing host cell contact. Moreover, tethering PopD at a dimer interface also specifically prevents host-cell sensing, arguing that the translocation pore is actively involved in detecting host cell contact. The work presented here therefore establishes a signal transduction pathway for sensing host cell contact that is initiated by a conformational change in the translocation pore, and is subsequently transmitted to the base of the apparatus via a specific contact between the pore and the T3SS needle-tip. PMID:27022930

  12. Discovery of a highly potent glucocorticoid for asthma treatment

    PubMed Central

    He, Yuanzheng; Shi, Jingjing; Yi, Wei; Ren, Xin; Gao, Xiang; Li, Jianshuang; Wu, Nanyan; Weaver, Kevin; Xie, Qian; Khoo, Sok Kean; Yang, Tao; Huang, Xiaozhu; Melcher, Karsten; Xu, H Eric

    2016-01-01

    Glucocorticoids are the most effective treatment for asthma. However, their clinical applications are limited by low efficacy in severe asthma and by undesired side effects associated with high dose or prolonged use. The most successful approach to overcome these limitations has been the development of highly potent glucocorticoids that can be delivered to the lungs by inhalation to achieve local efficacy with minimal systemic effects. On the basis of our previous structural studies, we designed and developed a highly potent glucocorticoid, VSGC12, which showed an improved anti-inflammation activity in both cell-based reporter assays and cytokine inhibition experiments, as well as in a gene expression profiling of mouse macrophage RAW264.7 cells. In a mouse asthma model, VSGC12 delivered a higher efficacy than fluticasone furoate, a leading clinical compound, in many categories including histology and the number of differentiated immune cells. VSGC12 also showed a higher potency than fluticasone furoate in repressing most asthma symptoms. Finally, VSGC12 showed a better side effect profile than fluticasone furoate at their respective effective doses, including better insulin response and less bone loss in an animal model. The excellent therapeutic and side effect properties of VSGC12 provide a promising perspective for developing this potent glucocorticoid as a new effective drug for asthma. PMID:27066265

  13. Differentiation of latex allergy from irritant contact dermatitis.

    PubMed

    Burkhart, Craig; Schloemer, Julie; Zirwas, Matthew

    2015-12-01

    The term latex allergy refers to a hypersensitivity to products containing natural rubber latex. Individuals with true latex allergy have developed type I (immediate) hypersensitivity due to previous sensitization and production of immunoglobulin E antibodies. Other forms of adverse reactions to latex-containing products may develop, including irritant contact dermatitis and type IV (delayed) hypersensitivity reactions, although they do not indicate true latex allergy. Several diagnostic tests are available to differentiate true latex allergy from irritant contact dermatitis and allergic contact dermatitis. It is crucial to determine the type of hypersensitivity in patients labeled with "latex allergy" in order to establish the most effective treatment regimen. PMID:26761937

  14. Fabrication of optically reflecting ohmic contacts for semiconductor devices

    DOEpatents

    Sopori, Bhushan L.

    1995-01-01

    A method is provided to produce a low-resistivity ohmic contact having high optical reflectivity on one side of a semiconductor device. The contact is formed by coating the semiconductor substrate with a thin metal film on the back reflecting side and then optically processing the wafer by illuminating it with electromagnetic radiation of a predetermined wavelength and energy level through the front side of the wafer for a predetermined period of time. This method produces a thin epitaxial alloy layer between the semiconductor substrate and the metal layer when a crystalline substrate is used. The alloy layer provides both a low-resistivity ohmic contact and high optical reflectance.

  15. Fabrication of optically reflecting ohmic contacts for semiconductor devices

    DOEpatents

    Sopori, B.L.

    1995-07-04

    A method is provided to produce a low-resistivity ohmic contact having high optical reflectivity on one side of a semiconductor device. The contact is formed by coating the semiconductor substrate with a thin metal film on the back reflecting side and then optically processing the wafer by illuminating it with electromagnetic radiation of a predetermined wavelength and energy level through the front side of the wafer for a predetermined period of time. This method produces a thin epitaxial alloy layer between the semiconductor substrate and the metal layer when a crystalline substrate is used. The alloy layer provides both a low-resistivity ohmic contact and high optical reflectance. 5 figs.

  16. Superconductor-normal-superconductor with distributed Sharvin point contacts

    DOEpatents

    Holcomb, Matthew J.; Little, William A.

    1994-01-01

    A non-linear superconducting junction device comprising a layer of high transient temperature superconducting material which is superconducting at an operating temperature, a layer of metal in contact with the layer of high temperature superconducting material and which remains non-superconducting at the operating temperature, and a metal material which is superconducting at the operating temperature and which forms distributed Sharvin point contacts with the metal layer.

  17. Hopf fibration and monopole connection over the contact quantum spheres

    NASA Astrophysics Data System (ADS)

    Brzeziński, Tomasz; Dąbrowski, Ludwik; Zieliński, Bartosz

    2004-04-01

    Non-commutative geometry of quantised contact spheres introduced by Omori et al. in [J. Math. Soc. Jpn. 50 (1998) 915; Noncommutative 3-sphere as an Example of Noncommutative Contact Algebras, Banach Center Publications, vol. 40, 1997, pp. 329-334] is studied. In particular it is proven that these spheres form a non-commutative Hopf fibration in the sense of Hopf-Galois extensions. The monopole (strong) connection is constructed, and projectors describing projective modules of all monopole charges are computed.

  18. Method for lubricating contacting surfaces

    SciTech Connect

    Dugger, Michael T.; Ohlhausen, James A.; Asay, David B.; Kim, Seong H.

    2011-12-06

    A method is provided for tribological lubrication of sliding contact surfaces, where two surfaces are in contact and in motion relative to each other, operating in a vapor-phase environment containing at least one alcohol compound at a concentration sufficiently high to provide one monolayer of coverage on at least one of the surfaces, where the alcohol compound continuously reacts at the surface to provide lubrication.

  19. Pose and motion from contact

    SciTech Connect

    Jia, Y.B.; Erdmann, M.

    1999-05-01

    In the absence of vision, grasping an object often relies on tactile feedback from the fingertips. As the finger pushes the object, the fingertip can feel the contact point move. If the object is known in advance, from this motion the finger may infer the location of the contact point on the object, and thereby, the object pose. This paper primarily investigates the problem of determining the pose (orientation and position) and motion (velocity and angular velocity) of a planar object with known geometry from such contact motion generated by pushing. A dynamic analysis of pushing yields a nonlinear system that relates through contact the object pose and motion to the finger motion. The contact motion on the fingertip thus encodes certain information about the object pose. Nonlinear observability theory is employed to show that such information is sufficient for the finger to observe not only the pose, but also the motion of the object. Therefore, a sensing strategy can be realized as an observer of the nonlinear dynamic system. Two observers are subsequently introduced. The first observer, based on the work of Gautheir, Hammouri, and Othman (1992), has its gain determined by the solution of a Lyapunov-like equation; it can be activated at any time instant during a push. The second observer, based on Newton`s method, solves for the initial (motionless) object pose from three intermediate contact points during a push. Under the Coulomb-friction model, the paper deals with support friction in the plane and/or contact friction between the finger and the object. Extensive simulations have been done to demonstrate the feasibility of the two observers. Preliminary experiments (with an Adept robot) have also been conducted. A contact sensor has been implemented using strain gauges.

  20. Discrete-contact nanowire photovoltaics

    NASA Astrophysics Data System (ADS)

    Chitambar, Michelle J.; Wen, Wen; Maldonado, Stephen

    2013-11-01

    A series of finite-element simulations have been performed to assess the operational characteristics of a new semiconductor nanowire solar cell design operating under high-level injection conditions. Specifically, the steady-state current-voltage behavior of a cylindrical silicon (Si) nanowire with a series of discrete, ohmic-selective contacts under intense sunlight illumination was investigated. The scope of the analysis was limited to only the factors that impact the net internal quantum yield for solar to electricity conversion. No evaluations were performed with regards to optical light trapping in the modeled structures. Several aspects in a discrete-contact nanowire device that could impact operation were explored, including the size and density of ohmic-selective contacts, the size of the nanowire, the electronic quality and conductivity of the nanowire, the surface defect density of the nanowire, and the type of ohmic selectivity employed at each contact. The analysis showed that there were ranges of values for each parameter that supported good to excellent photoresponses, with certain combinations of experimentally attainable material properties yielding internal energy conversion efficiencies at the thermodynamic limit for a single junction cell. The merits of the discrete-contact nanowire cell were contrasted with "conventional" nanowire photovoltaic cells featuring a uniform conformal contact and also with planar point-contact solar cells. The unique capacity of the discrete-contact nanowire solar cell design to operate at useful energy conversion efficiencies with low quality semiconductor nanowires (i.e., possessing short charge-carrier lifetimes) with only light doping is discussed. This work thus defines the impetus for future experimental work aimed at developing this photovoltaic architecture.

  1. Low resistance, nonalloyed Ohmic contacts to InGaAs

    NASA Astrophysics Data System (ADS)

    Crook, Adam M.; Lind, Erik; Griffith, Zach; Rodwell, Mark J. W.; Zimmerman, Jeremy D.; Gossard, Arthur C.; Bank, Seth R.

    2007-11-01

    We report extremely low specific contact resistivity (ρc) nonalloyed Ohmic contacts to n-type In0.53Ga0.47As, lattice matched to InP. Contacts were formed by oxidizing the semiconductor surface through exposure to ultraviolet-generated ozone, subsequently immersing the wafer in ammonium hydroxide (NH4OH, 14.8 normality), and finally depositing either Ti /Pd/Au contact metal by electron-beam evaporation or TiW contact metal by vacuum sputtering. Ti /Pd/Au contacts exhibited ρc of (0.73±0.44)Ωμm2—i.e., (7.3±4.4)×10-9Ωcm2—while TiW contacts exhibited ρc of (0.84±0.48)Ωμm2. The TiW contacts are thermally stable, showing no observable degradation in resistivity after a 500°C annealing of 1min duration.

  2. Use of contact lenses by firefighters: Part 2. Clinical evaluation.

    PubMed

    Owen, C G; Margrain, T H; Woodward, E G

    1997-05-01

    Contact lenses can be worn in a variety of environmental conditions and do not increase the wearers risk of injury. In many situations they offer significant corneal protection. Currently firefighters are prohibited from using contact lenses. To evaluate whether contact lenses are a safe form of visual correction 50 firefighters were fitted, and examined after 1, 4 and 10 months of contact lens wear. Twenty-nine were fitted with soft contact lenses, and 21 with rigid gas permeable contact lenses. Statistically significant increase in lid sulcus hyperaemia was found in both the SCL and RGPCL groups (P < 0.01, P = 0.02, respectively), as well as an increase in hyperaemia of the vertical quadrant of the bulbar conjunctivae (P = 0.01, P = 0.02, respectively). In addition the RGPCL group showed a statistically significant increase in hyperaemia of the lateral portion of the bulbar conjunctivae (P < 0.01), consistent with exposure epitheliopathy. The SCL group showed statistically significant increase in corneal staining in the vertical quadrant for all visits (P = 0.02, P = 0.01, P = 0.02 for all visits, respectively), indicative of lens dehydration. These findings although clinically significant are not unique to firefighting, and are found within a "normal" population of contact lens wearers. In conjunction with questionnaire data (Owen et all, 1996) we conclude that soft contact lenses can be worn safely by firefighters without additional risk. PMID:9196662

  3. Aurelia aurita (Cnidaria) Oocytes' Contact Plate Structure and Development

    PubMed Central

    Adonin, Leonid S.; Shaposhnikova, Tatyana G.; Podgornaya, Olga

    2012-01-01

    One of the A. aurita medusa main mesoglea polypeptides, mesoglein, has been described previously. Mesoglein belongs to ZP-domain protein family and therefore we focused on A.aurita oogenesis. Antibodies against mesoglein (AB RA47) stain the plate in the place where germinal epithelium contacts oocyte on the paraffin sections. According to its position, we named the structure found the “contact plate”. Our main instrument was AB against mesoglein. ZP-domain occupies about half of the whole amino acid sequence of the mesoglein. Immunoblot after SDS-PAGE and AU-PAGE reveals two charged and high Mr bands among the female gonad germinal epithelium polypeptides. One of the gonads' polypeptides Mr corresponds to that of mesogleal cells, the other ones' Mr is higher. The morphological description of contact plate formation is the subject of the current work. Two types of AB RA47 positive granules were observed during progressive oogenesis stages. Granules form the contact plate in mature oocyte. Contact plate of A.aurita oocyte marks its animal pole and resembles Zona Pellucida by the following features: (1) it attracts spermatozoids; (2) the material of the contact plate is synthesized by oocyte and stored in granules; (3) these granules and the contact plate itself contain ZP domain protein(s); (4) contact plate is an extracellular structure made up of fiber bundles similar to those of conventional Zona Pellucida. PMID:23185235

  4. Mechanisms of rolling contact spalling

    NASA Technical Reports Server (NTRS)

    Kumar, A. M.; Kulkarni, S. M.; Bhargava, V.; Hahn, G. T.; Rubin, C. A.

    1987-01-01

    The results of a study aimed at analyzing the mechanical material interactions responsible for rolling contact spalling of the 440 C steel, high pressure oxygen turbopump bearings are presented. A coupled temperature displacement finite element analysis of the effects of friction heating under the contact is presented. The contact is modelled as a stationary, heat generating, 2 dimensional indent in an elastic perfectly plastic half-space with heat fluxes up to 8.6 x 10000 KW/m sq comparable to those generated in the bearing. Local temperatures in excess of 1000 C are treated. The calculations reveal high levels of residual tension after the contact is unloaded and cools. Efforts to promote Mode 2/Mode 3 fatigue crack growth under cyclic torsion in hardened 440 C steel are described. Spalls produced on 440 C steel by a 3 ball/rod rolling contact testing machine were studied with scanning microscopy. The shapes of the cyclic, stress strain hysteresis loops displayed by hardened 440 C steel in cyclic torsion at room temperature are defined for the plastic strain amplitudes encountered in rolling/sliding contact. Results of these analyses are discussed in detail.

  5. Structure-activity relationship of flavonoids as potent inhibitors of carbonyl reductase 1 (CBR1).

    PubMed

    Arai, Yuki; Endo, Satoshi; Miyagi, Namiki; Abe, Naohito; Miura, Takeshi; Nishinaka, Toru; Terada, Tomoyuki; Oyama, Masayoshi; Goda, Hiroaki; El-Kabbani, Ossama; Hara, Akira; Matsunaga, Toshiyuki; Ikari, Akira

    2015-03-01

    Human carbonyl reductase 1 (CBR1), a member of the short-chain dehydrogenase/reductase superfamily, reduces a variety of carbonyl compounds including therapeutic drugs. CBR1 is involved in the reduction of the anthracycline anticancer drugs to their less anticancer C-13 hydroxy metabolites, which are cardiotoxic. CBR1 inhibitors are thought to be promising agents for adjuvant therapy with twofold beneficial effect in prolonging the anticancer efficacy of the anthracyclines while decreasing cardiotoxicity, a side effect of the drugs. In this study, we evaluated 27 flavonoids for their inhibitory activities of CBR1 in order to explore the structure-activity relationship (SAR). Among them, luteolin (2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4H-1-benzopyran-4-one) showed the most potent inhibition (IC5095nM), which is also more potent compared to all known classes of CBR1 inhibitors. The inhibition of luteolin was noncompetitive with respect to the substrate in the NADPH-dependent reduction direction, but CBR1 exhibited moderate NADP(+)-dependent dehydrogenase activity for some alicyclic alcohols, in which the luteolin inhibition was competitive with respect to the alcohol substrate (Ki59nM). The SAR of the flavonoids indicated that the 7-hydroxy group of luteolin was responsible for the potent inhibition of CBR1. The molecular docking of luteolin in CBR1-NADPH complex showed that theflavonoid binds to the substrate-binding cleft, in which its 7-hydroxy group formed a H-bond with main-chain oxygen of Met234, in addition to H-bond interactions (of its 5-hydroxy and 4-carbonyl groups with catalytically important residues Tyr193 and/or Ser139) and a π-stacking interaction (between its phenyl ring and Trp229). PMID:25549925

  6. New substrate analogues of human serotonin N-acetyltransferase produce in situ specific and potent inhibitors.

    PubMed

    Ferry, Gilles; Ubeaud, Caroline; Mozo, Julien; Péan, Christophe; Hennig, Philippe; Rodriguez, Marianne; Scoul, Catherine; Bonnaud, Anne; Nosjean, Olivier; Galizzi, Jean-Pierre; Delagrange, Philippe; Renard, Pierre; Volland, Jean-Paul; Yous, Said; Lesieur, Daniel; Boutin, Jean A

    2004-01-01

    Melatonin is synthesized by an enzymatic pathway, in which arylalkylamine (serotonin) N-acetyltransferase catalyzes the rate-limiting step. A previous study reported the discovery of bromoacetyltryptamine (BAT), a new type of inhibitor of this enzyme. This compound is the precursor of a potent bifunctional inhibitor (analogue of the transition state), capable of interfering with both the substrate and the cosubstrate binding sites. This inhibitor is biosynthesized by the enzyme itself in the presence of free coenzyme A. In the present report, we describe the potency of new N-halogenoacetyl derivatives leading to a strong in situ inhibition of serotonin N-acetyltransferase. The new concept behind the mechanism of action of these precursors was studied by following the biosynthesis of the inhibitor from tritiated-BAT in a living cell. The fate of tritiated-phenylethylamine (PEA), a natural substrate of the enzyme, in the presence or absence of [(3)H]BAT was also followed, leading to their incorporation into the reaction product or the inhibitor (N-acetyl[(3)H]PEA and coenzyme A-S[(3)H]acetyltryptamine, respectively). The biosynthesis of this bifunctional inhibitor derived from BAT was also followed by nuclear magnetic resonance during its catalytic production by the pure enzyme. In a similar manner we studied the production of another inhibitor generated from N-[2-(7-hydroxynaphth-1-yl)ethyl]bromoacetamide. New derivatives were also screened for their capacity to inhibit a purified enzyme, in addition to enzyme overexpressed in a cellular model. Some of these compounds proved to be extremely potent, with IC(50)s of approximately 30 nM. As these compounds, by definition, closely resemble the natural substrates of arylalkylamine N-acetyltransferase, we also show that they are potent ligands at the melatonin receptors. Nevertheless, these inhibitors form a series of pharmacological tools that could be used to understand more closely the inhibition of pineal melatonin production in vivo. PMID:14717709

  7. Crane-Load Contact Sensor

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert; Mata, Carlos; Cox, Robert

    2005-01-01

    An electronic instrument has been developed as a prototype of a portable crane-load contact sensor. Such a sensor could be helpful in an application in which the load rests on a base in a horizontal position determined by vertical alignment pins (see Figure 1). If the crane is not positioned to lift the load precisely vertically, then the load can be expected to swing once it has been lifted clear of the pins. If the load is especially heavy, large, and/or fragile, it could hurt workers and/or damage itself and nearby objects. By indicating whether the load remains in contact with the pins when it has been lifted a fraction of the length of the pins, the crane-load contact sensor helps the crane operator determine whether it is safe to lift the load clear of the pins: If there is contact, then the load is resting against the sides of the pins and, hence, it may not be safe to lift; if contact is occasionally broken, then the load is probably not resting against the pins, so it should be safe to lift. It is assumed that the load and base, or at least the pins and the surfaces of the alignment holes in the load, are electrically conductive, so the instrument can use electrical contact to indicate mechanical contact. However, DC resistance cannot be used as an indicator of contact for the following reasons: The load and the base are both electrically grounded through cables (the load is grounded through the lifting cable of the crane) to prevent discharge of static electricity. In other words, the DC resistance between the load and the pins is always low, as though they were always in direct contact. Therefore, instead of DC resistance, the instrument utilizes the AC electrical impedance between the pins and the load. The signal frequency used in the measurement is high enough (.1 MHz) that the impedance contributed by the cables and the electrical ground network of the building in which the crane and the base are situated is significantly greater than the contact impedance between the pins and the load. The instrument includes a signal generator and voltage-measuring circuitry, and is connected to the load and the base as shown in Figure 2. The output of the signal generator (typically having amplitude of the order of a volt) is applied to the load via a 50-resistor, and the voltage between the load and the pins is measured. When the load and the pins are not in contact, the impedance between them is relatively high, causing the measured voltage to exceed a threshold value. When the load and the pins are in contact, the impedance between them falls to a much lower value, causing the voltage to fall below the threshold value. The voltage-measuring circuitry turns on a red light-emitting diode (LED) to indicate the lower-voltage/ contact condition. Whenever the contact has been broken and the non-contact/higher-voltage condition has lasted for more than 2 ms, the voltage-measuring circuitry indicates this condition by blinking a green LED.

  8. Role of membrane contact sites in protein import into mitochondria

    PubMed Central

    Horvath, Susanne E; Rampelt, Heike; Oeljeklaus, Silke; Warscheid, Bettina; van der Laan, Martin; Pfanner, Nikolaus

    2015-01-01

    Mitochondria import more than 1,000 different proteins from the cytosol. The proteins are synthesized as precursors on cytosolic ribosomes and are translocated by protein transport machineries of the mitochondrial membranes. Five main pathways for protein import into mitochondria have been identified. Most pathways use the translocase of the outer mitochondrial membrane (TOM) as the entry gate into mitochondria. Depending on specific signals contained in the precursors, the proteins are subsequently transferred to different intramitochondrial translocases. In this article, we discuss the connection between protein import and mitochondrial membrane architecture. Mitochondria possess two membranes. It is a long-standing question how contact sites between outer and inner membranes are formed and which role the contact sites play in the translocation of precursor proteins. A major translocation contact site is formed between the TOM complex and the presequence translocase of the inner membrane (TIM23 complex), promoting transfer of presequence-carrying preproteins to the mitochondrial inner membrane and matrix. Recent findings led to the identification of contact sites that involve the mitochondrial contact site and cristae organizing system (MICOS) of the inner membrane. MICOS plays a dual role. It is crucial for maintaining the inner membrane cristae architecture and forms contacts sites to the outer membrane that promote translocation of precursor proteins into the intermembrane space and outer membrane of mitochondria. The view is emerging that the mitochondrial protein translocases do not function as independent units, but are embedded in a network of interactions with machineries that control mitochondrial activity and architecture. PMID:25514890

  9. Ferromagnetic tunnel contacts to graphene: Contact resistance and spin signal

    SciTech Connect

    Cubukcu, M.; Laczkowski, P.; Vergnaud, C.; Marty, A.; Attané, J.-P.; Notin, L.; Vila, L. Jamet, M.; Martin, M.-B.; Seneor, P.; Anane, A.; Deranlot, C.; Fert, A.; Auffret, S.; Ducruet, C.

    2015-02-28

    We report spin transport in CVD graphene-based lateral spin valves using different magnetic contacts. We compared the spin signal amplitude measured on devices where the cobalt layer is directly in contact with the graphene to the one obtained using tunnel contacts. Although a sizeable spin signal (up to ∼2 Ω) is obtained with direct contacts, the signal is strongly enhanced (∼400 Ω) by inserting a tunnel barrier. In addition, we studied the resistance-area product (R.A) of a variety of contacts on CVD graphene. In particular, we compared the R.A products of alumina and magnesium oxide tunnel barriers grown by sputtering deposition of aluminum or magnesium and subsequent natural oxidation under pure oxygen atmosphere or by plasma. When using an alumina tunnel barrier on CVD graphene, the R.A product is high and exhibits a large dispersion. This dispersion can be highly reduced by using a magnesium oxide tunnel barrier, as for the R.A value. This study gives insight in the material quest for reproducible and efficient spin injection in CVD graphene.

  10. Contact Lens-Related Eye Infections

    MedlinePlus

    ... Ophthalmologist Español Eye Health / Eye Health A-Z Contact Lens-Related Eye Infections Sections Contact Lens-Related ... About Contact Lenses Proper Care of Contact Lenses Contact Lens-Related Eye Infections Written by: Kierstan Boyd ...

  11. Solar cell with back side contacts

    DOEpatents

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J; Wanlass, Mark Woodbury; Clews, Peggy J

    2013-12-24

    A III-V solar cell is described herein that includes all back side contacts. Additionally, the positive and negative electrical contacts contact compoud semiconductor layers of the solar cell other than the absorbing layer of the solar cell. That is, the positive and negative electrical contacts contact passivating layers of the solar cell.

  12. RF Sputtering of Gold Contacts On Niobium

    NASA Technical Reports Server (NTRS)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  13. N° 28-1998: SOHO spacecraft contacted

    NASA Astrophysics Data System (ADS)

    Contact has been re-established with the ESA/NASA Solar and Heliospheric Observatory (SOHO) following six weeks of silence. Signals sent yesterday through the NASA Deep Space Network (DSN) station at Canberra, Australia, were answered at 22:51 GMT in the form of bursts of signal lasting from 2 to 10 seconds. These signals were recorded both by the NASA DSN station and the ESA Perth station. Contact is being maintained through the NASA DSN stations at Goldstone (California), Canberra and Madrid (Spain). Although the signals are intermittent and do not contain any data information, they show that the spacecraft is still capable of receiving and responding to ground commands. The slow process of regaining control of the spacecraft and restoring it to an operational attitude will commence immediately, with attempts to initiate data transmissions in order to perform an initial assessment of the spacecraft on-board conditions. Radio contact with SOHO, a joint mission of the European Space Agency and NASA, was interrupted on 25 June (see ESA press releases N°24,25 and 26-98). More information on SOHO, including mission status reports is available on the Internet at http://sohowww.estec.esa.nl or via the new ESA science website: http://sci.esa.int

  14. On the structure of contact binaries. I - The contact discontinuity

    NASA Technical Reports Server (NTRS)

    Shu, F. H.; Lubow, S. H.; Anderson, L.

    1976-01-01

    The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified.

  15. Reduced contact resistance in top-contact organic field-effect transistors by interface contact doping

    NASA Astrophysics Data System (ADS)

    Hou, Ji-Ling; Kasemann, Daniel; Widmer, Johannes; Günther, Alrun A.; Lüssem, Björn; Leo, Karl

    2016-03-01

    Emerging organic integrated electronics require capability of high speed and the compatibility with high-resolution structuring processes such as photolithography. When downscaling the channel length, the contact resistance is known to limit the performance of the short channel devices. In this report, orthogonal photolithography is used for the patterning of the source/drain electrodes of the organic field-effect transistors (OFETs) as well as the interface dopant insertion layers for further modifications of the contact resistance. Bottom-gate top-contact pentacene OFETs with different thicknesses of the p-dopant 2,2'-(perfluoronaphthalene-2,6-diylidene)dimalononitrile under the Au electrodes show a significant decrease in threshold voltage from -2.2 V to -0.8 V and in contact resistance from 55 k Ω cm to 10 k Ω cm by adding a 1 nm thin dopant interlayer. The influence of doping on charge carrier injection is directly visible in the temperature-dependent output characteristics and a charge-transfer activation energy of ˜20 meV is obtained. Our results provide a systematic study of interface contact doping and also show the connection between interface contact doping and improved charge carrier injection by the activation of charge transfer process.

  16. Enlargement of Axo-Somatic Contacts Formed by GAD-Immunoreactive Axon Terminals onto Layer V Pyramidal Neurons in the Medial Prefrontal Cortex of Adolescent Female Mice Is Associated with Suppression of Food Restriction-Evoked Hyperactivity and Resilience to Activity-Based Anorexia.

    PubMed

    Chen, Yi-Wen; Wable, Gauri Satish; Chowdhury, Tara Gunkali; Aoki, Chiye

    2016-06-01

    Many, but not all, adolescent female mice that are exposed to a running wheel while food restricted (FR) become excessive wheel runners, choosing to run even during the hours of food availability, to the point of death. This phenomenon is called activity-based anorexia (ABA). We used electron microscopic immunocytochemistry to ask whether individual differences in ABA resilience may correlate with the lengths of axo-somatic contacts made by GABAergic axon terminals onto layer 5 pyramidal neurons (L5P) in the prefrontal cortex. Contact lengths were, on average, 40% greater for the ABA-induced mice, relative to controls. Correspondingly, the proportion of L5P perikaryal plasma membrane contacted by GABAergic terminals was 45% greater for the ABA mice. Contact lengths in the anterior cingulate cortex correlated negatively and strongly with the overall wheel activity after FR (R = -0.87, P < 0.01), whereas those in the prelimbic cortex correlated negatively with wheel running specifically during the hours of food availability of the FR days (R = -0.84, P < 0.05). These negative correlations support the idea that increases in the glutamic acid decarboxylase (GAD) terminal contact lengths onto L5P contribute toward ABA resilience through suppression of wheel running, a behavior that is intrinsically rewarding and helpful for foraging but maladaptive within a cage. PMID:25979087

  17. Contact angle and film pressure: study of a talc surface.

    PubMed

    Douillard, J M; Zajac, J; Malandrini, H; Clauss, F

    2002-11-15

    Talc samples in both sheet and powder form are studied by adsorption calorimetry and adsorption isotherm techniques. A model is used to determine the solid surface energy, the solid surface tension and the dispersive, acidic, and basic components of these terms. These results are introduced in an approximate equation relating adsorption to contact angle data. Experimental contact angles are in correct agreement with this approach. The Neumann equation of state is used to fit the data and discussed. It appears as a numerical form of the general equation taking into account gas adsorption and film pressure. Behaviors of talc in contact with liquids do not appear very different whether the solid is in sheet or powder form. PMID:12505082

  18. Discovery of the highly potent fluoroquinolone-based benzothiazolyl-4-thiazolidinone hybrids as antibacterials.

    PubMed

    Patel, Rahul V; Park, Se Won

    2014-07-01

    A new series of fluoroquinolone-based benzothiazolyl-4-thiazolidinone hybrids has been yielded via sulfated tungstate-promoted highly accelerated N-formylation at a piperazine residue of ciprofloxacin and norfloxacin entities. The formylated fluoroquinolone moieties were then coupled with substituted 2-aminobenzothiazoles, which were generated from their respective para-substituted amines to form corresponding Schiff base intermediates. The Schiff bases were then treated with thioglycolic acid to equip a new class of 4-thiazolidinones to be analyzed for their antibacterial effects against two Gram-positive (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains and were found highly potent with lowest Minimum inhibitory concentrations (MIC), 1-2 μg/mL, that is, more potent than control drugs ciprofloxacin (3.12-6.25 μg/mL). Initial outcomes provided for these novel molecular systems will aid researchers to design and develop new antibacterial drugs. The structural assignments of the new products were done on the basis of FT-IR, (1) H NMR and (13) C NMR spectroscopy, and elemental analysis. PMID:24524270

  19. SARS Patients and Their Close Contacts

    MedlinePlus

    ... Fact Sheet for SARS Patients and Their Close Contacts Format: Select one PDF [256 KB] Recommend on ... that are not now known. What does "close contact" mean? In the context of SARS, close contact ...

  20. Multimodal characterization of contact lenses

    NASA Astrophysics Data System (ADS)

    Marcus, Michael A.; Compertore, David; Gibson, Donald S.; Herbrand, Matthew E.; Ignatovich, Filipp V.

    2015-10-01

    A table top instrument has been designed, constructed and tested to characterize all of the primary optical and physical properties of contact lenses. Measured optical properties include base power, cylinder power, cylindrical axis, prism, refractive index and wavefront aberrations. Measured physical properties include center thickness, lens diameter and lens sagittal depth. The instrument combines a Shack-Hartmann wavefront sensor (SHWS), a machine vision sensor, and a low coherence light interferometer (LCI) all coaxially aligned into a single tabletop unit. The unit includes a cuvette, mounted in a translatable sample chamber for holding the contact lens under test, and it can be configured to measure wet or dry contact lenses. During operation, the vision sensor measures the diameter of the lens, and locates the center of the lens. The lens is then aligned for other measurements. The vision sensor can also measure various alignment marks on the lens, as well as identify any alpha numerical features, which can be used to associate the lens orientation with the measured aberrations. The LCI measures the center thickness, sagittal depth and index of refraction of the contact lens. The base radius of curvature is then calculated using these measured parameters. The SHWS measures the lenses prescription power, including spherical, cylinder, prism, and higher order wavefront aberrations. NIST traceable calibration artifacts are used to calibrate the SHWS, machine vision and LCI modalities. Repeatability measurements on a contact lens in a saline solution are presented.

  1. Marine Bioinspired Underwater Contact Adhesion.

    PubMed

    Clancy, Sean K; Sodano, Antonio; Cunningham, Dylan J; Huang, Sharon S; Zalicki, Piotr J; Shin, Seunghan; Ahn, B Kollbe

    2016-05-01

    Marine mussels and barnacles are sessile biofouling organisms that adhere to a number of surfaces in wet environments and maintain remarkably strong bonds. Previous synthetic approaches to mimic biological wet adhesive properties have focused mainly on the catechol moiety, present in mussel foot proteins (mfps), and especially rich in the interfacial mfps, for example, mfp-3 and -5, found at the interface between the mussel plaque and substrate. Barnacles, however, do not use Dopa for their wet adhesion, but are instead rich in noncatecholic aromatic residues. Due to this anomaly, we were intrigued to study the initial contact adhesion properties of copolymerized acrylate films containing the key functionalities of barnacle cement proteins and interfacial mfps, for example, aromatic (catecholic or noncatecholic), cationic, anionic, and nonpolar residues. The initial wet contact adhesion of the copolymers was measured using a probe tack testing apparatus with a flat-punch contact geometry. The wet contact adhesion of an optimized, bioinspired copolymer film was ∼15.0 N/cm(2) in deionized water and ∼9.0 N/cm(2) in artificial seawater, up to 150 times greater than commercial pressure-sensitive adhesive (PSA) tapes (∼0.1 N/cm(2)). Furthermore, maximum wet contact adhesion was obtained at ∼pH 7, suggesting viability for biomedical applications. PMID:27046671

  2. Contact damping in microelectromechanical actuators

    NASA Astrophysics Data System (ADS)

    Khater, M. E.; Akhtar, S.; Park, S.; Ozdemir, S.; Abdel-Rahman, E.; Vyasarayani, C. P.; Yavuz, M.

    2014-12-01

    We examine the significance of the energy loss mechanisms active in electrostatic MEMS actuators. We find that the dominant loss mechanism changes depending on the actuator mode of operation. We find that the active mechanisms in the order of their significance are: fluid-structure interactions dominant for actuators operating in air, actuator-substrate interactions dominant for actuators in contact with a substrate under vacuum, and intrinsic loss mechanisms dominant for actuators in-flight under vacuum. Further, experimental results show that the quality factor of an electrostatic MEMS actuator drops drastically as the actuator first comes into line contact with a substrate. As the contact area expands along the actuator length, the quality factor increases. Measurements under 1 Torr vacuum show a three-fold increase in the quality factor as the contact area expands from a line to 30% of the actuator area. This increase in the quality factor is attributed to the drop in the contribution of friction forces into energy losses as contact expands and adhesion forces increase.

  3. The Effect of Contact Angle on the Depletion Layer when Water Meets a Hydrophobic Surface

    NASA Astrophysics Data System (ADS)

    Poynor, Adele

    2013-03-01

    By definition hydrophobic substances hate water. Water placed on a hydrophobic surface will form a drop in order to minimize its contact area. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low-density depletion layer forms near the surface. We investigate the effect of contact angle on depletion layer formation using the surface sensitive technique of Surface Plasmon Resonance.

  4. Method and apparatus for high-efficiency direct contact condensation

    DOEpatents

    Bharathan, Desikan; Parent, Yves; Hassani, A. Vahab

    1999-01-01

    A direct contact condenser having a downward vapor flow chamber and an upward vapor flow chamber, wherein each of the vapor flow chambers includes a plurality of cooling liquid supplying pipes and a vapor-liquid contact medium disposed thereunder to facilitate contact and direct heat exchange between the vapor and cooling liquid. The contact medium includes a plurality of sheets arranged to form vertical interleaved channels or passageways for the vapor and cooling liquid streams. The upward vapor flow chamber also includes a second set of cooling liquid supplying pipes disposed beneath the vapor-liquid contact medium which operate intermittently in response to a pressure differential within the upward vapor flow chamber. The condenser further includes separate wells for collecting condensate and cooling liquid from each of the vapor flow chambers. In alternate embodiments, the condenser includes a cross-current flow chamber and an upward flow chamber, a plurality of upward flow chambers, or a single upward flow chamber. The method of use of the direct contact condenser of this invention includes passing a vapor stream sequentially through the downward and upward vapor flow chambers, where the vapor is condensed as a result of heat exchange with the cooling liquid in the contact medium. The concentration of noncondensable gases in the resulting condensate-liquid mixtures can be minimized by controlling the partial pressure of the vapor, which depends in part upon the geometry of the vapor-liquid contact medium. In another aspect of this invention, the physical and chemical performance of a direct contact condenser can be predicted based on the vapor and coolant compositions, the condensation conditions. and the geometric properties of the contact medium.

  5. Method and apparatus for high-efficiency direct contact condensation

    DOEpatents

    Bharathan, D.; Parent, Y.; Hassani, A.V.

    1999-07-20

    A direct contact condenser having a downward vapor flow chamber and an upward vapor flow chamber, wherein each of the vapor flow chambers includes a plurality of cooling liquid supplying pipes and a vapor-liquid contact medium disposed thereunder to facilitate contact and direct heat exchange between the vapor and cooling liquid. The contact medium includes a plurality of sheets arranged to form vertical interleaved channels or passageways for the vapor and cooling liquid streams. The upward vapor flow chamber also includes a second set of cooling liquid supplying pipes disposed beneath the vapor-liquid contact medium which operate intermittently in response to a pressure differential within the upward vapor flow chamber. The condenser further includes separate wells for collecting condensate and cooling liquid from each of the vapor flow chambers. In alternate embodiments, the condenser includes a cross-current flow chamber and an upward flow chamber, a plurality of upward flow chambers, or a single upward flow chamber. The method of use of the direct contact condenser of this invention includes passing a vapor stream sequentially through the downward and upward vapor flow chambers, where the vapor is condensed as a result of heat exchange with the cooling liquid in the contact medium. The concentration of noncondensable gases in the resulting condensate-liquid mixtures can be minimized by controlling the partial pressure of the vapor, which depends in part upon the geometry of the vapor-liquid contact medium. In another aspect of this invention, the physical and chemical performance of a direct contact condenser can be predicted based on the vapor and coolant compositions, the condensation conditions, and the geometric properties of the contact medium. 39 figs.

  6. An analytical method for computing atomic contact areas in biomolecules.

    PubMed

    Mach, Paul; Koehl, Patrice

    2013-01-15

    We propose a new analytical method for detecting and computing contacts between atoms in biomolecules. It is based on the alpha shape theory and proceeds in three steps. First, we compute the weighted Delaunay triangulation of the union of spheres representing the molecule. In the second step, the Delaunay complex is filtered to derive the dual complex. Finally, contacts between spheres are collected. In this approach, two atoms i and j are defined to be in contact if their centers are connected by an edge in the dual complex. The contact areas between atom i and its neighbors are computed based on the caps formed by these neighbors on the surface of i; the total area of all these caps is partitioned according to their spherical Laguerre Voronoi diagram on the surface of i. This method is analytical and its implementation in a new program BallContact is fast and robust. We have used BallContact to study contacts in a database of 1551 high resolution protein structures. We show that with this new definition of atomic contacts, we generate realistic representations of the environments of atoms and residues within a protein. In particular, we establish the importance of nonpolar contact areas that complement the information represented by the accessible surface areas. This new method bears similarity to the tessellation methods used to quantify atomic volumes and contacts, with the advantage that it does not require the presence of explicit solvent molecules if the surface of the protein is to be considered. © 2012 Wiley Periodicals, Inc. PMID:22965816

  7. 78 FR 14549 - National Contact Center; Information Collection; National Contact Center Customer Evaluation Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... ADMINISTRATION National Contact Center; Information Collection; National Contact Center Customer Evaluation Survey AGENCY: Contact Center Services, Federal Citizen Information Center, Office of Citizen Services... requirement regarding the National Contact Center customer evaluation surveys. In this request, the...

  8. Scaling effects in Schottky contacts

    NASA Astrophysics Data System (ADS)

    Ruzin, A.

    2015-11-01

    This article reports on scaling effects in Schottky contacts on various types of semiconductors, including low resistivity, semi-intrinsic, and deep-level compensated. The investigation was performed using a finite element computation and drift-diffusion transport model. In low resistivity semiconductors, the currents scale with contact area as long as thermionic emission process dominates the current transport, with limited impact of velocity saturation effect. In high resistivity semiconductors, the scaling is much more complex due to the considerable impact of minority carrier contribution. In several cases, the currents scale with contact radius, rather than with area, due to corresponding electric field variations. In some compensated materials, the impact of velocity saturation was shown to boost the current, due to carrier accumulation and corresponding space charge variations.

  9. Formation of 10-Formylfolic Acid, a Potent Inhibitor of Dihydrofolate Reductase, in Rat Liver Slices Incubated with Folic Acid

    PubMed Central

    d'Urso-Scott, M.; Uhoch, J.; Bertino, J. R.

    1974-01-01

    During investigation of folate polyglutamate biosynthesis in rat liver slices utilizing [2-14C]folic acid, a folate compound that behaved like a polyglutamate form in the Sephadex G-15 gel filtration system was found to accumulate. Subsequent chromatographic, spectral, chemical, and enzymic studies have indicated that the compound formed in liver slices incubated with [14C]folic acid with and without methotrexate was 10-formyl folate. This folate is of interest in that it is the most potent natural inhibitor of dihydrofolate reductase known and may be capable of serving a regulatory function within the cell. PMID:4527808

  10. A potent hypotensive factor in chicken left ventricle.

    PubMed

    Reilly, T; Gregg, C M; Wideman, R F; Jarrett-Zaczek, D

    1987-12-01

    Chicken artria and ventricles both have membrane-bound granules which resemble those containing atriopeptin (ANP) in mammals. However, nothing is known about the contents of the avian granules. A previous study in chickens showed that although extracts of whole chicken heart or synthetic rat ANP both caused profound hypotension, ANP caused both natriuresis and diuresis, while chicken heart extract did not. The present study sought to locate the region(s) of chicken heart containing the hypotensive activity, and to observe the effect on sodium and water excretion and blood pressure in rats. Acid extracts of either atrium, either ventricle, ventricular septum, skeletal muscle, and liver were identically prepared from chickens and rats. Extracts were adjusted to the same protein concentration and injected (0.15 ml/kg) into anesthetized Single Comb White Leghorn roosters. Mean arterial pressure (MAP) and the time for recovery were measured. The most potent extract from chicken hearts was from the left ventricle (-38 +/- 1 mm Hg, 149 +/- 9 sec to recover). All other extracts (including right ventricle) produced only small (10-20 mm Hg), short-lived (20-30 sec) decreases in MAP. In contrast, only rat atrial extracts evoked long-lasting hypotension (greater than 40 mm Hg, recovery time greater than 200 sec). A 30-min infusion of the most potent chicken extract (left ventricle, CLV) into rats produced a small but significant natriuresis and diuresis compared to the vehicle time control (P less than 0.05) and the hypotensive response to bolus injection was about one-third that seen in the chicken. The location of potent spasmolytic activity primarily in chicken left ventricle, the different avian renal responses to chicken heart extract and synthetic rat ANP (5), and the weak diuretic, natriuretic, and hypotensive effects of CLV extract in rats all suggest that the chicken heart substance may be different from mammalian ANP. PMID:2962198

  11. A potent hypotensive factor in chicken left ventricle.

    TOXLINE Toxicology Bibliographic Information

    Reilly T; Gregg CM; Wideman RF Jr; Jarrett-Zaczek D

    1987-12-01

    Chicken artria and ventricles both have membrane-bound granules which resemble those containing atriopeptin (ANP) in mammals. However, nothing is known about the contents of the avian granules. A previous study in chickens showed that although extracts of whole chicken heart or synthetic rat ANP both caused profound hypotension, ANP caused both natriuresis and diuresis, while chicken heart extract did not. The present study sought to locate the region(s) of chicken heart containing the hypotensive activity, and to observe the effect on sodium and water excretion and blood pressure in rats. Acid extracts of either atrium, either ventricle, ventricular septum, skeletal muscle, and liver were identically prepared from chickens and rats. Extracts were adjusted to the same protein concentration and injected (0.15 ml/kg) into anesthetized Single Comb White Leghorn roosters. Mean arterial pressure (MAP) and the time for recovery were measured. The most potent extract from chicken hearts was from the left ventricle (-38 +/- 1 mm Hg, 149 +/- 9 sec to recover). All other extracts (including right ventricle) produced only small (10-20 mm Hg), short-lived (20-30 sec) decreases in MAP. In contrast, only rat atrial extracts evoked long-lasting hypotension (greater than 40 mm Hg, recovery time greater than 200 sec). A 30-min infusion of the most potent chicken extract (left ventricle, CLV) into rats produced a small but significant natriuresis and diuresis compared to the vehicle time control (P less than 0.05) and the hypotensive response to bolus injection was about one-third that seen in the chicken. The location of potent spasmolytic activity primarily in chicken left ventricle, the different avian renal responses to chicken heart extract and synthetic rat ANP (5), and the weak diuretic, natriuretic, and hypotensive effects of CLV extract in rats all suggest that the chicken heart substance may be different from mammalian ANP.

  12. Design of potent substrate-analogue inhibitors of canine renin

    NASA Technical Reports Server (NTRS)

    Hui, K. Y.; Siragy, H. M.; Haber, E.

    1992-01-01

    Through a systematic study of structure-activity relationships, we designed potent renin inhibitors for use in dog models. In assays against dog plasma renin at neutral pH, we found that, as in previous studies of rat renin inhibitors, the structure at the P2 position appears to be important for potency. The substitution of Val for His at this position increases potency by one order of magnitude. At the P3 position, potency appears to depend on a hydrophobic side chain that does not necessarily have to be aromatic. Our results also support the approach of optimizing potency in a renin inhibitor by introducing a moiety that promotes aqueous solubility (an amino group) at the C-terminus of the substrate analogue. In the design of potent dog plasma renin inhibitors, the influence of the transition-state residue 4(S)-amino-3(S)-hydroxy-5-cyclohexylpentanoic acid (ACHPA)-commonly used as a substitute for the scissile-bond dipeptide to boost potency-is not obvious, and appears to be sequence dependent. The canine renin inhibitor Ac-paF-Pro-Phe-Val-statine-Leu-Phe-paF-NH2 (compound 15; IC50 of 1.7 nM against dog plasma renin at pH 7.4; statine, 4(S)-amino-3(S)-hydroxy-6-methylheptanoic acid; paF, para-aminophenylalanine) had a potent hypotensive effect when infused intravenously into conscious, sodium-depleted, normotensive dogs. Also, compound 15 concurrently inhibited plasma renin activity and had a profound diuretic effect.

  13. Vaginal concentrations of lactic acid potently inactivate HIV

    PubMed Central

    Aldunate, Muriel; Tyssen, David; Johnson, Adam; Zakir, Tasnim; Sonza, Secondo; Moench, Thomas; Cone, Richard; Tachedjian, Gilda

    2013-01-01

    Objectives When Lactobacillus spp. dominate the vaginal microbiota of women of reproductive age they acidify the vagina to pH <4.0 by producing ∼1% lactic acid in a nearly racemic mixture of d- and l-isomers. We determined the HIV virucidal activity of racemic lactic acid, and its d- and l-isomers, compared with acetic acid and acidity alone (by the addition of HCl). Methods HIV-1 and HIV-2 were transiently treated with acids in the absence or presence of human genital secretions at 37°C for different time intervals, then immediately neutralized and residual infectivity determined in the TZM-bl reporter cell line. Results l-lactic acid at 0.3% (w/w) was 17-fold more potent than d-lactic acid in inactivating HIVBa-L. Complete inactivation of different HIV-1 subtypes and HIV-2 was achieved with ≥0.4% (w/w) l-lactic acid. At a typical vaginal pH of 3.8, l-lactic acid at 1% (w/w) more potently and rapidly inactivated HIVBa-L and HIV-1 transmitter/founder strains compared with 1% (w/w) acetic acid and with acidity alone, all adjusted to pH 3.8. A final concentration of 1% (w/w) l-lactic acid maximally inactivated HIVBa-L in the presence of cervicovaginal secretions and seminal plasma. The anti-HIV activity of l-lactic acid was pH dependent, being abrogated at neutral pH, indicating that its virucidal activity is mediated by protonated lactic acid and not the lactate anion. Conclusions l-lactic acid at physiological concentrations demonstrates potent HIV virucidal activity distinct from acidity alone and greater than acetic acid, suggesting a protective role in the sexual transmission of HIV. PMID:23657804

  14. Caterpillar dermatitis revisited: lepidopterism after contact with oak processionary caterpillar

    PubMed Central

    Müller, Cornelia S L; Tilgen, Wolfgang; Pföhler, Claudia

    2011-01-01

    Caterpillar dermatitis (lepidopterism) is a disease that is caused by butterflies, moths and their caterpillars. Clinical signs and symptoms vary from itchy skin lesions to conjunctivitis, pharyngitis, malaise and anaphylactic reactions. We present the case of two brothers with typical skin lesions of leptidopterism. The older boy showed skin lesions after playing with caterpillars in the garden, whereas his younger brother was affected without direct contact to the caterpillars but only by playing with his brother. As the mother could show two caterpillars, lepidopterism could easily be diagnosed. Under a local therapy with a medium potent corticosteroid cream and a non-sedating orally administered antihistamine, all skin lesions as well as itching disappeared within 1 week. PMID:22696629

  15. Dermatitis, contact on the cheek (image)

    MedlinePlus

    ... skin inflammation (dermatitis) on the cheek caused by contact with a substance that produced an allergic reaction (allergen). Contact dermatitis causes redness, itching, and small blisters (vesicles).

  16. Contacts de langues et representations (Language Contacts and Representations).

    ERIC Educational Resources Information Center

    Matthey, Marinette, Ed.

    1997-01-01

    Essays on language contact and the image of language, entirely in French, include: "Representations 'du' contexte et representations 'en' contexte? Eleves et enseignants face a l'apprentissage de la langue" ("Representations 'of' Context or Representations 'in' Context? Students and Teachers Facing Language Learning" (Laurent Gajo); "Le crepuscule…

  17. Applying a Multitarget Rational Drug Design Strategy: a First Set of Modulators with Potent and Balanced Activity toward Dopamine D3 Receptor and Fatty Acid Amide Hydrolase

    PubMed Central

    De Simone, Alessio; Filippo, Gian; Albani, Clara; Tarozzo, Glauco; Bandiera, Tiziano; Piomelli, Daniele; Cavalli, Andrea; Bottegoni, Giovanni

    2014-01-01

    Combining computer-assisted drug design and synthetic efforts, we generated compounds with potent and balanced activities toward both D3 dopamine receptor and fatty acid amide hydrolase (FAAH) enzyme. Concurrently modulating these targets, our compounds hold a great potential toward exerting a disease-modifying effect on nicotine addiction and other forms of compulsive behavior. PMID:24691497

  18. Potent, selective spiropyrrolidine pyrimidinetrione inhibitors of MMP-13.

    PubMed

    Freeman-Cook, Kevin D; Reiter, Lawrence A; Noe, Mark C; Antipas, Amy S; Danley, Dennis E; Datta, Kaushik; Downs, James T; Eisenbeis, Shane; Eskra, James D; Garmene, David J; Greer, Elaine M; Griffiths, Richard J; Guzman, Roberto; Hardink, Joel R; Janat, Fouad; Jones, Christopher S; Martinelli, Gary J; Mitchell, Peter G; Laird, Ellen R; Liras, Jennifer L; Lopresti-Morrow, Lori L; Pandit, Jayvardhan; Reilly, Usa D; Robertson, Donald; Vaughn-Bowser, Marcie L; Wolf-Gouviea, Lilli A; Yocum, Sue A

    2007-12-01

    Explorations in the pyrimidinetrione series of MMP-13 inhibitors led to the discovery of a series of spiro-fused compounds that are potent and selective inhibitors of MMP-13. While other spiro-fused motifs are hydrolytically unstable, presumably due to electronic destabilization of the pyrimidinetrione ring, the spiropyrrolidine series does not share this liability. Greater than 100-fold selectivity versus other MMP family members was achieved by incorporation of an extended aryl-heteroaryl P1'group. When dosed as the sodium salt, these compounds displayed excellent oral absorption and pharmacokinetic properties. Despite the selectivity, a representative of this series produced fibroplasia in a 14 day rat study. PMID:17935984

  19. Pyrazolopyridines as potent PDE4B inhibitors: 5-Heterocycle SAR

    SciTech Connect

    Mitchell, Charlotte J.; Ballantine, Stuart P.; Coe, Diane M.; Cook, Caroline M.; Delves, Christopher J.; Dowle, Mike D.; Edlin, Chris D.; Hamblin, J. Nicole; Holman, Stuart; Johnson, Martin R.; Jones, Paul S.; Keeling, Sue E.; Kranz, Michael; Lindvall, Mika; Lucas, Fiona S.; Neu, Margarete; Solanke, Yemisi E.; Somers, Don O.; Trivedi, Naimisha A.; Wiseman, Joanne O.

    2012-05-03

    Following the discovery of 4-(substituted amino)-1-alkyl-pyrazolo[3,4-b]pyridine-5-carboxamides as potent and selective phosphodiesterase 4B inhibitors, [Hamblin, J. N.; Angell, T.; Ballentine, S., et al. Bioorg. Med. Chem. Lett.2008, 18, 4237] the SAR of the 5-position was investigated further. A range of substituted heterocycles showed good potencies against PDE4. Optimisation using X-ray crystallography and computational modelling led to the discovery of 16, with sub-nM inhibition of LPS-induced TNF-{alpha} production from isolated human peripheral blood mononuclear cells.

  20. New potent calcimimetics: II. Discovery of benzothiazole trisubstituted ureas.

    PubMed

    Deprez, Pierre; Temal, Taoues; Jary, Hélène; Auberval, Marielle; Lively, Sarah; Guédin, Denis; Vevert, Jean-Paul

    2013-04-15

    Following the identification of trisubstituted ureas as a promising new chemical series of allosteric modulators of the calcium sensing receptor (CaSR), we further explored the SAR around the urea substitution, leading to the discovery of benzothiazole urea compound 13. This compound is a potent calcimimetic with an EC50=20 nM (luciferase assay). Evaluated in an in vivo model of chronic renal failure (short term and long term in 5/6 nephrectomized rats), benzothiazole urea 13 significantly decreased PTH levels after oral administration while keeping calcemia within the normal range. PMID:23499504

  1. Discovery of Tertiary Sulfonamides as Potent Liver X Receptor Antagonists

    SciTech Connect

    Zuercher, William J.; Buckholz†, Richard G.; Campobasso, Nino; Collins, Jon L.; Galardi, Cristin M.; Gampe, Robert T.; Hyatt, Stephen M.; Merrihew, Susan L.; Moore, John T.; Oplinger, Jeffrey A.; Reid, Paul R.; Spearing, Paul K.; Stanley, Thomas B.; Stewart, Eugene L.; Willson, Timothy M.

    2010-08-12

    Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists. GSK2033 (17) is the first potent cell-active LXR antagonist described to date. 17 may be a useful chemical probe to explore the cell biology of this orphan nuclear receptor.

  2. Organometallic osmium arene complexes with potent cancer cell cytotoxicity.

    PubMed

    Fu, Ying; Habtemariam, Abraha; Pizarro, Ana M; van Rijt, Sabine H; Healey, David J; Cooper, Patricia A; Shnyder, Steven D; Clarkson, Guy J; Sadler, Peter J

    2010-11-25

    Iodido osmium(II) complexes [Os(η(6)-arene)(XY)I](+) (XY = p-hydroxy or p-dimethylaminophenylazopyridine, arene = p-cymene or biphenyl) are potently cytotoxic at nanomolar concentrations toward a panel of human cancer cell lines; e.g., IC(50) = 140 nM for [Os(η(6)-bip)(azpy-NMe(2))I](+) toward A2780 ovarian cancer cells. They exhibit low toxicity and negligible deleterious effects in a colon cancer xenograft model, giving rise to the possibility of a broad therapeutic window. The most active complexes are stable and inert toward aquation. Their cytotoxic activity appears to involve redox mechanisms. PMID:20977192

  3. Kisameet Clay Exhibits Potent Antibacterial Activity against the ESKAPE Pathogens

    PubMed Central

    Behroozian, Shekooh; Svensson, Sarah L.

    2016-01-01

    ABSTRACT The ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens cause an increasing number of nosocomial infections worldwide since they escape the inhibitory effect of the available antibiotics and the immune response. Here, we report the broad-spectrum and potent antibacterial activity of Kisameet clay, a natural clay mineral from British Columbia, Canada, against a group of multidrug-resistant ESKAPE strains. The results suggest that this natural clay might be developed as a therapeutic option for the treatment of serious infections caused by these important pathogens. PMID:26814180

  4. Novel racemic tetrahydrocurcuminoid dihydropyrimidinone analogues as potent acetylcholinesterase inhibitors.

    PubMed

    Arunkhamkaew, Sarawalee; Athipornchai, Anan; Apiratikul, Nuttapon; Suksamrarn, Apichart; Ajavakom, Vachiraporn

    2013-05-15

    The synthesis of racemic tetrahydrocurcumin- (THC-), tetrahydrodemethoxycurcumin- (THDC-) and tetrahydrobisdemethoxycurcumin- (THBDC-) dihydropyrimidinone (DHPM) analogues was achieved by utilizing the multi-component Biginelli reaction in the presence of copper sulphate as a catalyst. The evaluation of acetylcholinesterase inhibitors for Alzheimer's disease of these compounds showed that they exhibited higher inhibitory activity than their parent analogues. THBDC-DHPM demonstrated the most potent inhibitory activity with an IC50 value of 1.34±0.03μM which was more active than the approved drug galanthamine (IC50=1.45±0.04μM). PMID:23583510

  5. Synthesis of Novel Compounds as New Potent Tyrosinase Inhibitors

    PubMed Central

    Hamidian, Hooshang

    2013-01-01

    In the present paper, we report the synthesis and pharmacological evaluation of a new series of azo compounds with different groups (1-naphthol, 2-naphthol, and N,N-dimethylaniline) and trifluoromethoxy and fluoro substituents in the scaffold. All synthesized compounds (5a–5f) showed the most potent mushroom tyrosinase inhibition (IC50 values in the range of 4.39 ± 0.76–1.71 ± 0.49 µM), comparable to the kojic acid, as reference standard inhibitor. All the novel compounds were characterized by FT-IR, 1H NMR, 13C NMR, and elemental analysis. PMID:24260737

  6. [Selection and study of potent lactose-fermenting yeasts].

    PubMed

    Golubev, V I; Golubev, N V

    2004-01-01

    Whey-fermenting Kluyveromyces cultures were revealed among 105 yeast strains assimilating lactose. Eighteen most potent strains isolated from milk products fermented galactose, sucrose, and raffinose, in addition to lactose. Many yeast strains fermented inulin. Most strains were resistant to cycloheximide and grew in medium containing glucose, NaCl, and ethanol at concentrations of up to 50, 11-12, and 10-12%, respectively (4 degrees C). Three strains had mycocinogenic activity. After fermentation of whey with selected yeast strains at 30 degrees C for 2-3 days, ethanol concentration was 4-5%. PMID:15283337

  7. Potent antitubulin tumor cell cytotoxins based on 3-aroyl indazoles.

    PubMed

    Duan, Jian-Xin; Cai, Xiaohong; Meng, Fanying; Lan, Leslie; Hart, Charles; Matteucci, Mark

    2007-03-01

    A series of 3-aroyl indazoles was synthesized. Modification of the C-7 position resulted in a significant structure-activity relationship (SAR) with acetylene modifications conferring unusual potency in a tumor cell cytotoxicity assay. The most potent compounds exceeded the activity of combretastatin A4 (CA-4), showing single digit nM IC50 values against all cell lines tested including those with known efflux resistance pumps. The inhibition of in vitro tubulin polymerization was comparable to CA-4, consistent with tubulin being the target for these compounds. Competition binding experiments employing [3H]colchicine and purified tubulins demonstrated that the compound specifically binds to the colchicine site. PMID:17286393

  8. Trigocherrierin A, a potent inhibitor of chikungunya virus replication.

    PubMed

    Bourjot, Mélanie; Leyssen, Pieter; Neyts, Johan; Dumontet, Vincent; Litaudon, Marc

    2014-01-01

    Trigocherrierin A (1) and trigocherriolide E (2), two new daphnane diterpenoid orthoesters (DDOs), and six chlorinated analogues, trigocherrins A, B, F and trigocherriolides A-C, were isolated from the leaves of Trigonostemon cherrieri. Their structures were identified by mass spectrometry, extensive one- and two-dimensional NMR spectroscopy and through comparison with data reported in the literature. These compounds are potent and selective inhibitors of chikungunya virus (CHIKV) replication. Among the DDOs isolated, compound 1 exhibited the strongest anti-CHIKV activity (EC₅₀ = 0.6 ± 0.1 µM, SI = 71.7). PMID:24662077

  9. Non- contacting capacitive diagnostic device

    DOEpatents

    Ellison, Timothy

    2005-07-12

    A non-contacting capacitive diagnostic device includes a pulsed light source for producing an electric field in a semiconductor or photovoltaic device or material to be evaluated and a circuit responsive to the electric field. The circuit is not in physical contact with the device or material being evaluated and produces an electrical signal characteristic of the electric field produced in the device or material. The diagnostic device permits quality control and evaluation of semiconductor or photovoltaic device properties in continuous manufacturing processes.

  10. Point contact silicon solar cells

    NASA Technical Reports Server (NTRS)

    Swanson, R. M.

    1986-01-01

    The construction of a 22.2% efficient single-crystal silicon solar cell fabricated at Stanford University is described. The cell dimensions were 3 x 5 mm and 100 microns thick with a base lifetime of 500 microseconds. The cell featured light trapping between a texturized top surface and a reflective bottom surface, small point contact diffusions, alternating between n-type and p-type in a polka-dot pattern on the bottom surface, and a surface passivation on all surfaces between contact regions.

  11. Nanotechnology and Food Contact Materials

    NASA Astrophysics Data System (ADS)

    Papaspyrides, Constantine (Costas) D.

    2010-06-01

    The use of nanotechnology in food contact materials is highlighted in relation to novel applications and potential implications for consumer safety and regulatory controls. Nanotechnology applications are expected to bring a range of benefits to the food sector, including improved packaging, antimicrobial properties, traceability and security of food products. The toxicological nature of hazard, likelihood of exposure and risk to consumers from nanotechnology-derived food/food packaging are largely unknown and this work highlights the benefits of nanotechnology in food contact materials but also the gaps in knowledge regarding consumers safety that require further research.

  12. Contacts of space--times

    SciTech Connect

    Maia, M.D.

    1981-03-01

    The concept of contact between manifolds is applied to space--times of general relativity. For a given background space--time a contact approximation of second order is defined and interpreted both from the point of view of a metric pertubation and of a higher order tangent manifold. In the first case, an application to the high frequency gravitational wave hypothesis is suggested. In the second case, a constant curvature tangent bundle is constructed and suggested as a means to define a ten parameter local space--time symmetry.

  13. Using Tutte polynomials to characterize sexual contact networks

    NASA Astrophysics Data System (ADS)

    Cadavid Muñoz, Juan José

    2014-06-01

    Tutte polynomials are used to characterize the dynamic and topology of the sexual contact networks, in which pathogens are transmitted as an epidemic. Tutte polynomials provide an algebraic characterization of the sexual contact networks and allow the projection of spread control strategies for sexual transmission diseases. With the usage of Tutte polynomials, it allows obtaining algebraic expressions for the basic reproductive number of different pathogenic agents. Computations are done using the computer algebra software Maple, and it's GraphTheory Package. The topological complexity of a contact network is represented by the algebraic complexity of the correspondent polynomial. The change in the topology of the contact network is represented as a change in the algebraic form of the associated polynomial. With the usage of the Tutte polynomials, the number of spanning trees for each contact network can be obtained. From the obtained results in the polynomial form, it can be said that Tutte polynomials are of great importance for designing and implementing control measures for slowing down the propagation of sexual transmitted pathologies. As a future research line, the analysis of weighted sexual contact networks using weighted Tutte polynomials is considered.

  14. First principles study of metal contacts to monolayer black phosphorous

    SciTech Connect

    Chanana, Anuja; Mahapatra, Santanu

    2014-11-28

    Atomically thin layered black phosphorous (BP) has recently appeared as an alternative to the transitional metal dichalcogenides for future channel material in a metal-oxide-semiconductor transistor due to its lower carrier effective mass. Investigation of the electronic property of source/drain contact involving metal and two-dimensional material is essential as it impacts the transistor performance. In this paper, we perform a systematic and rigorous study to evaluate the Ohmic nature of the side-contact formed by the monolayer BP (mBP) and metals (gold, titanium, and palladium), which are commonly used in experiments. Employing the Density Functional Theory, we analyse the potential barrier, charge transfer and atomic orbital overlap at the metal-mBP interface in an optimized structure to understand how efficiently carriers could be injected from metal contact to the mBP channel. Our analysis shows that gold forms a Schottky contact with a higher tunnel barrier at the interface in comparison to the titanium and palladium. mBP contact with palladium is found to be purely Ohmic, where as titanium contact demonstrates an intermediate behaviour.

  15. Back contact buffer layer for thin-film solar cells

    DOEpatents

    Compaan, Alvin D.; Plotnikov, Victor V.

    2014-09-09

    A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.

  16. Morphology and the Strength of Intermolecular Contact in Protein Crystals

    NASA Technical Reports Server (NTRS)

    Matsuura, Yoshiki; Chernov, Alexander A.

    2002-01-01

    The strengths of intermolecular contacts (macrobonds) in four lysozyme crystals were estimated based on the strengths of individual intermolecular interatomic interaction pairs. The periodic bond chain of these macrobonds accounts for the morphology of protein crystals as shown previously. Further in this paper, the surface area of contact, polar coordinate representation of contact site, Coulombic contribution on the macrobond strength, and the surface energy of the crystal have been evaluated. Comparing location of intermolecular contacts in different polymorphic crystal modifications, we show that these contacts can form a wide variety of patches on the molecular surface. The patches are located practically everywhere on this surface except for the concave active site. The contacts frequently include water molecules, with specific intermolecular hydrogen-bonds on the background of non-specific attractive interactions. The strengths of macrobonds are also compared to those of other protein complex systems. Making use of the contact strengths and taking into account bond hydration we also estimated crystal-water interfacial energies for different crystal faces.

  17. End-bonded contacts for carbon nanotube transistors with low, size-independent resistance

    NASA Astrophysics Data System (ADS)

    Cao, Qing; Han, Shu-Jen; Tersoff, Jerry; Franklin, Aaron D.; Zhu, Yu; Zhang, Zhen; Tulevski, George S.; Tang, Jianshi; Haensch, Wilfried

    2015-10-01

    Moving beyond the limits of silicon transistors requires both a high-performance channel and high-quality electrical contacts. Carbon nanotubes provide high-performance channels below 10 nanometers, but as with silicon, the increase in contact resistance with decreasing size becomes a major performance roadblock. We report a single-walled carbon nanotube (SWNT) transistor technology with an end-bonded contact scheme that leads to size-independent contact resistance to overcome the scaling limits of conventional side-bonded or planar contact schemes. A high-performance SWNT transistor was fabricated with a sub-10-nanometer contact length, showing a device resistance below 36 kilohms and on-current above 15 microampere per tube. The p-type end-bonded contact, formed through the reaction of molybdenum with the SWNT to form carbide, also exhibited no Schottky barrier. This strategy promises high-performance SWNT transistors, enabling future ultimately scaled device technologies.

  18. Optofluidic realization and retaining of cell–cell contact using an abrupt tapered optical fibre

    PubMed Central

    Xin, Hongbao; Zhang, Yao; Lei, Hongxiang; Li, Yayi; Zhang, Huixian; Li, Baojun

    2013-01-01

    Studies reveal that there exists much interaction and communication between bacterial cells, with parts of these social behaviors depending on cell–cell contacts. The cell–cell contact has proved to be crucial for determining various biochemical processes. However, for cell culture with relatively low cell concentration, it is difficult to precisely control and retain the contact of a small group of cells. Particularly, the retaining of cell–cell contact is difficult when flows occur in the medium. Here, we report an optofluidic method for realization and retaining of Escherichia coli cell–cell contact in a microfluidic channel using an abrupt tapered optical fibre. The contact process is based on launching a 980-nm wavelength laser into the fibre, E. coli cells were trapped onto the fibre tip one after another, retaining cell–cell contact and forming a highly organized cell chain. The formed chains further show the ability as bio-optical waveguides. PMID:23771190

  19. Thermal and electrical contact conductance studies

    NASA Technical Reports Server (NTRS)

    Vansciver, S. W.; Nilles, M.

    1985-01-01

    Prediction of electrical and thermal contact resistance for pressed, nominally flat contacts is complicated by the large number of variables which influence contact formation. This is reflected in experimental results as a wide variation in contact resistances, spanning up to six orders of magnitude. A series of experiments were performed to observe the effects of oxidation and surface roughness on contact resistance. Electrical contact resistance and thermal contact conductance from 4 to 290 K on OFHC Cu contacts are reported. Electrical contact resistance was measured with a 4-wire DC technique. Thermal contact conductance was determined by steady-state longitudinal heat flow. Corrections for the bulk contribution ot the overall measured resistance were made, with the remaining resistance due solely to the presence of the contact.

  20. Ball bearing lubrication: The elastohydrodynamics of elliptical contacts

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    The history of ball bearings is examined, taking into account rollers and the wheel in the early civilizations, the development of early forms of rolling-element bearings in the classical civilizations, the Middle Ages, the Industrial Revolution, the emergence of the precision ball bearing, scientific studies of contact mechanics and rolling friction, and the past fifty years. An introduction to ball bearings is presented, and aspects of ball bearing mechanics are explored. Basic characteristics of lubrication are considered along with lubrication equations, the lubrication of rigid ellipsoidal solids, and elastohydrodynamic lubrication theory. Attention is given to the theoretical results for fully flooded elliptical hydrodynamic contacts, the theoretical results for starved elliptical contacts, experimental investigations, the elastohydrodynamics of elliptical contacts for materials of low elastic modulus, the film thickness for different regimes of fluid-film lubrication, and applications.

  1. Growth of contact area between rough surfaces under normal stress

    NASA Astrophysics Data System (ADS)

    Stesky, R. M.; Hannan, S. S.

    1987-05-01

    The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

  2. Emerging magnetic order in platinum atomic contacts and chains

    PubMed Central

    Strigl, Florian; Espy, Christopher; Bückle, Maximilian; Scheer, Elke; Pietsch, Torsten

    2015-01-01

    The development of atomic-scale structures revealing novel transport phenomena is a major goal of nanotechnology. Examples include chains of atoms that form while stretching a transition metal contact or the predicted formation of magnetic order in these chains, the existence of which is still debated. Here we report an experimental study of the magneto-conductance (MC) and anisotropic MC with atomic-size contacts and mono-atomic chains of the nonmagnetic metal platinum. We find a pronounced and diverse MC behaviour, the amplitude and functional dependence change when stretching the contact by subatomic distances. These findings can be interpreted as a signature of local magnetic order in the chain, which may be of particular importance for the application of atomic-sized contacts in spintronic devices of the smallest possible size. PMID:25649440

  3. Contact Geometry of Hyperbolic Equations of Generic Type

    NASA Astrophysics Data System (ADS)

    The, Dennis

    2008-08-01

    We study the contact geometry of scalar second order hyperbolic equations in the plane of generic type. Following a derivation of parametrized contact-invariants to distinguish Monge-Ampère (class 6-6), Goursat (class 6-7) and generic (class 7-7) hyperbolic equations, we use Cartan's equivalence method to study the generic case. An intriguing feature of this class of equations is that every generic hyperbolic equation admits at most a nine-dimensional contact symmetry algebra. The nine-dimensional bound is sharp: normal forms for the contact-equivalence classes of these maximally symmetric generic hyperbolic equations are derived and explicit symmetry algebras are presented. Moreover, these maximally symmetric equations are Darboux integrable. An enumeration of several submaximally symmetric (eight and seven-dimensional) generic hyperbolic structures is also given.

  4. Imaging surface contacts: Power law contact distributions and contact stresses in quartz, calcite, glass and acrylic plastic

    USGS Publications Warehouse

    Dieterich, J.H.; Kilgore, B.D.

    1996-01-01

    A procedure has been developed to obtain microscope images of regions of contact between roughened surfaces of transparent materials, while the surfaces are subjected to static loads or undergoing frictional slip. Static loading experiments with quartz, calcite, soda-lime glass and acrylic plastic at normal stresses to 30 MPa yield power law distributions of contact areas from the smallest contacts that can be resolved (3.5 ??m2) up to a limiting size that correlates with the grain size of the abrasive grit used to roughen the surfaces. In each material, increasing normal stress results in a roughly linear increase of the real area of contact. Mechanisms of contact area increase are by growth of existing contacts, coalescence of contacts and appearance of new contacts. Mean contacts stresses are consistent with the indentation strength of each material. Contact size distributions are insensitive to normal stress indicating that the increase of contact area is approximately self-similar. The contact images and contact distributions are modeled using simulations of surfaces with random fractal topographies. The contact process for model fractal surfaces is represented by the simple expedient of removing material at regions where surface irregularities overlap. Synthetic contact images created by this approach reproduce observed characteristics of the contacts and demonstrate that the exponent in the power law distributions depends on the scaling exponent used to generate the surface topography.

  5. The effectiveness of potent dental adhesives on the viability of LPS challenged human gingival fibroblasts.

    PubMed

    Garner, Angelia D; Tucci, Michelle A; Benghuzzi, Hamed A

    2014-01-01

    Dental adhesives are necessary for the retention of specific dental restorations utilized to repair the anatomy of the tooth after dental decay is removed. Adhesives come into contact with healthy and diseased periodontal tissues. Porphyromonas gingivalis is a gram negative bacterial pathogen, and lipopolysaccharide (LPS-PG) is an endotoxin found in gingival connective tissues of patients who suffer from periodontal disease. The presence of the endotoxin causes inflammation. This study aims to evaluate the effectiveness of potent dental adhesives when human gingival fibroblasts are challenged with LPS-PG. The fibroblasts were exposed to the dental adhesives polymethly methacrylate (PMMA), OptiBond®, and Prime & Bond® which were purchased from Patterson Dental, a national dental materials supplier. The human gingival fibroblasts (HGF-1, ATCC® CRL-2014™) were purchased from American Type Culture Collection (ATCC). The porphyromonas gingival lipopolysaccharide (LPS-PG) was purchased from Fisher Scientific (Pittsburg, PA). No significant differences in metabolic behavior was detected among the groups (p<0.132). While the glutathione assay determined that there was not any significant increase in oxidative stress levels; the lactate dehydrogenase assay identified significant cellular damage in the group exposed to combinations of the Prime & Bond® adhesives and LPS-PG at 48 hour intervals (p<0.003). No significant changes were noted in cellular morphology at any phases, and all cells demonstrated typical fibroblast spindle shape. PMID:25405402

  6. Assessing Measures of Contact Theory.

    ERIC Educational Resources Information Center

    Brown, William R.; Patchen, Martin

    This paper consolidates findings from two related studies: William Brown's research on the predictive ability of measures of early and non-high school interracial contact/opportunities that appear to affect interracial attitudes and behaviors in high school; and Martin Patchen's investigation in Indianapolis, Indiana high schools analyzing the…

  7. Electrical contact tool set station

    DOEpatents

    Byers, M.E.

    1988-02-22

    An apparatus is provided for the precise setting to zero of electrically conductive cutting tools used in the machining of work pieces. An electrically conductive cylindrical pin, tapered at one end to a small flat, rests in a vee-shaped channel in a base so that its longitudinal axis is parallel to the longitudinal axis of the machine's spindle. Electronic apparatus is connected between the cylindrical pin and the electrically conductive cutting tool to produce a detectable signal when contact between tool and pin is made. The axes of the machine are set to zero by contact between the cutting tool and the sides, end or top of the cylindrical pin. Upon contact, an electrical circuit is completed, and the detectable signal is produced. The tool can then be set to zero for that axis. Should the tool contact the cylindrical pin with too much force, the cylindrical pin would be harmlessly dislodged from the vee-shaped channel, preventing damage either to the cutting tool or the cylindrical pin. 5 figs.

  8. Ohmic contacts to semiconducting diamond

    NASA Astrophysics Data System (ADS)

    Zeidler, James R.; Taylor, M. J.; Zeisse, Carl R.; Hewett, C. A.; Delahoussaye, Paul R.

    1990-10-01

    Work was carried out to improve the electron beam evaporation system in order to achieve better deposited films. The basic system is an ion pumped vacuum chamber, with a three-hearth, single-gun e-beam evaporator. Four improvements were made to the system. The system was thoroughly cleaned and new ion pump elements, an e-gun beam adjust unit, and a more accurate crystal monitor were installed. The system now has a base pressure of 3 X 10(exp -9) Torr, and can easily deposit high-melting-temperature metals such as Ta with an accurately controlled thickness. Improved shadow masks were also fabricated for better alignment and control of corner contacts for electrical transport measurements. Appendices include: A Thermally Activated Solid State Reaction Process for Fabricating Ohmic Contacts to Semiconducting Diamond; Tantalum Ohmic Contacts to Diamond by a Solid State Reaction Process; Metallization of Semiconducting Diamond: Mo, Mo/Au, and Mo/Ni/Au; Specific Contact Resistance Measurements of Ohmic Contracts to Diamond; and Electrical Activation of Boron Implanted into Diamond.

  9. Contact symmetries and Hamiltonian thermodynamics

    SciTech Connect

    Bravetti, A.; Lopez-Monsalvo, C.S.; Nettel, F.

    2015-10-15

    It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher’s Information Matrix. In this work we analyse several unaddressed aspects about the application of contact and metric geometry to thermodynamics. We consider here the Thermodynamic Phase Space and start by investigating the role of gauge transformations and Legendre symmetries for metric contact manifolds and their significance in thermodynamics. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the Thermodynamic Phase Space for which the Legendre symmetry is broken. Moreover, we use contact Hamiltonian dynamics to represent thermodynamic processes in a way that resembles the classical Hamiltonian formulation of conservative mechanics and we show that the relevant Hamiltonian coincides with the irreversible entropy production along thermodynamic processes. Therefore, we use such property to give a geometric definition of thermodynamically admissible fluctuations according to the Second Law of thermodynamics. Finally, we show that the length of a curve describing a thermodynamic process measures its entropy production.

  10. DISEASES CAUSED BY WATER CONTACT

    EPA Science Inventory

    Diseases associated with water contact are reviewed with respect to the sources of etiological agents, the types of diseases and the conditions under which they occur. The sources of disease agents fall into three general groups; point sources such as sewage treatment plants; dis...

  11. Potent Reversible Inhibition of Myeloperoxidase by Aromatic Hydroxamates*

    PubMed Central

    Forbes, Louisa V.; Sjögren, Tove; Auchère, Françoise; Jenkins, David W.; Thong, Bob; Laughton, David; Hemsley, Paul; Pairaudeau, Garry; Turner, Rufus; Eriksson, Håkan; Unitt, John F.; Kettle, Anthony J.

    2013-01-01

    The neutrophil enzyme myeloperoxidase (MPO) promotes oxidative stress in numerous inflammatory pathologies by producing hypohalous acids. Its inadvertent activity is a prime target for pharmacological control. Previously, salicylhydroxamic acid was reported to be a weak reversible inhibitor of MPO. We aimed to identify related hydroxamates that are good inhibitors of the enzyme. We report on three hydroxamates as the first potent reversible inhibitors of MPO. The chlorination activity of purified MPO was inhibited by 50% by a 5 nm concentration of a trifluoromethyl-substituted aromatic hydroxamate, HX1. The hydroxamates were specific for MPO in neutrophils and more potent toward MPO compared with a broad range of redox enzymes and alternative targets. Surface plasmon resonance measurements showed that the strength of binding of hydroxamates to MPO correlated with the degree of enzyme inhibition. The crystal structure of MPO-HX1 revealed that the inhibitor was bound within the active site cavity above the heme and blocked the substrate channel. HX1 was a mixed-type inhibitor of the halogenation activity of MPO with respect to both hydrogen peroxide and halide. Spectral analyses demonstrated that hydroxamates can act variably as substrates for MPO and convert the enzyme to a nitrosyl ferrous intermediate. This property was unrelated to their ability to inhibit MPO. We propose that aromatic hydroxamates bind tightly to the active site of MPO and prevent it from producing hypohalous acids. This mode of reversible inhibition has potential for blocking the activity of MPO and limiting oxidative stress during inflammation. PMID:24194519

  12. Isolation of Potent CGRP Neutralizing Antibodies Using Four Simple Assays.

    PubMed

    Neal, Frances; Arnold, Joanne; Rossant, Christine J; Podichetty, Sadhana; Lowne, David; Dobson, Claire; Wilkinson, Trevor; Colley, Caroline; Howes, Rob; Vaughan, Tristan J

    2016-01-01

    Calcitonin gene-related peptide (CGRP) is a small neuropeptide and a potent vasodilator that is widely associated with chronic pain and migraine. An antibody that inhibits CGRP function would be a potential therapeutic for treatment of these disorders. Here we describe the isolation of highly potent antibodies to CGRP from phage and ribosome display libraries and characterization of their epitope, species cross-reactivity, kinetics, and functional activity. Homogenous time-resolved fluorescence (HTRF) binding assays identified antibodies with the desired species cross-reactivity from naïve libraries, and HTRF epitope competition assays were used to characterize and group scFv by epitope. The functional inhibition of CGRP and species cross-reactivity of purified scFv and antibodies were subsequently confirmed using cAMP assays. We show that epitope competition assays could be used as a surrogate for functional cell-based assays during affinity maturation, in combination with scFv off-rate ranking by biolayer interferometry (BLI). This is the first time it has been shown that off-rate ranking can be predictive of functional activity for anti-CGRP antibodies. Here we demonstrate how, by using just four simple assays, diverse panels of antibodies to CGRP can be identified. These assay formats have potential utility in the identification of antibodies to other therapeutic targets. PMID:26450103

  13. Synthesis, molecular modeling, and biological evaluation of novel chiral thiosemicarbazone derivatives as potent anticancer agents.

    PubMed

    Taşdemir, Demet; Karaküçük-İyidoğan, Ayşegül; Ulaşli, Mustafa; Taşkin-Tok, Tuğba; Oruç-Emre, Emİne Elçİn; Bayram, Hasan

    2015-02-01

    A series of new chiral thiosemicarbazones derived from homochiral amines in both enantiomeric forms were synthesized and evaluated for their in vitro antiproliferative activity against A549 (human alveolar adenocarcinoma), MCF-7 (human breast adenocarcinoma), HeLa (human cervical adenocarcinoma), and HGC-27 (human stomach carcinoma) cell lines. Some of compounds showed inhibitory activities on the growth of cancer cell lines. Especially, compound exhibited the most potent activity (IC50 4.6 μM) against HGC-27 as compared with the reference compound, sindaxel (IC50 10.3 μM), and could be used as a lead compound to search new chiral thiosemicarbazone derivatives as antiproliferative agents. PMID:25399965

  14. Synthesis of potent and orally efficacious 11β-hydroxysteroid dehydrogenase type 1 inhibitor HSD-016.

    PubMed

    Wan, Zhao-Kui; Chenail, Eva; Li, Huan-Qiu; Kendall, Christopher; Wang, Youchu; Gingras, Stéphane; Xiang, Jason; Massefski, Walter W; Mansour, Tarek S; Saiah, Eddine

    2011-09-01

    Cortisol and the glucocorticoid receptor (GR) signaling pathway has been linked to the development of diabetes and metabolic syndrome. In vivo, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyzes the conversion of inactive cortisone to its active form, cortisol. Existing clinical data have supported 11β-HSD1 as a valid therapeutic target for type 2 diabetes. In our research program, (R)-1,1,1-trifluoro-2-(3-((R)-4-(4-fluoro-2-(trifluoromethyl)phenyl)-2-methylpiperazin-1-ylsulfonyl)phenyl)propan-2-ol (HSD-016) was discovered to be a potent, selective, and efficacious 11β-HSD1 inhibitor and advanced as a clinical candidate. Herein, a reliable and scalable synthesis of HSD-016 is described. Key transformations include an asymmetric synthesis of a chiral tertiary alcohol via Sharpless dihydroxylation, epoxide formation, and subsequent mild reduction. This route ensured multikilogram quantities of HSD-016 necessary for clinical studies. PMID:21736359

  15. Proteolytic processing of QSOX1A ensures efficient secretion of a potent disulfide catalyst

    PubMed Central

    Rudolf, Jana; Pringle, MarieA.; Bulleid, NeilJ.

    2013-01-01

    QSOX1 (quiescin sulfhydryl oxidase 1) efficiently catalyses the insertion of disulfide bonds into a wide range of proteins. The enzyme is mechanistically well characterized, but its subcellular location and the identity of its protein substrates remain ill-defined. The function of QSOX1 is likely to involve disulfide formation in proteins entering the secretory pathway or outside the cell. In the present study, we show that this enzyme is efficiently secreted from mammalian cells despite the presence of a transmembrane domain. We identify internal cleavage sites and demonstrate that the protein is processed within the Golgi apparatus to yield soluble enzyme. As a consequence of this efficient processing, QSOX1 is probably functional outside the cell. Also, QSOX1 forms a dimer upon cleavage of the C-terminal domain. The processing of QSOX1 suggests a novel level of regulation of secretion of this potent disulfide catalyst and producer of hydrogen peroxide. PMID:23713614

  16. Chemoproteomics-Enabled Discovery of a Potent and Selective Inhibitor of the DNA Repair Protein MGMT.

    PubMed

    Wang, Chao; Abegg, Daniel; Hoch, Dominic G; Adibekian, Alexander

    2016-02-01

    We present a novel chemical scaffold for cysteine-reactive covalent inhibitors. Chloromethyl triazoles (CMTs) are readily accessed in only two chemical steps, thus enabling the rapid optimization of the pharmacological properties of these inhibitors. We demonstrate the tunability of the CMTs towards a specific biological target by synthesizing AA-CW236 as the first potent non-pseudosubstrate inhibitor of the O(6) -alkylguanine DNA methyltransferase (MGMT), a protein of major clinical significance for the treatment of several severe cancer forms. Using quantitative proteomics profiling techniques, we show that AA-CW236 exhibits a high degree of selectivity towards MGMT. Finally, we validate the effectiveness of our MGMT inhibitor in combination with the DNA alkylating drug temozolomide in breast and colon cancer cells by fluorescence imaging and a cell-viability assay. Our results may open a new avenue towards the development of a clinically approved MGMT inhibitor. PMID:26798972

  17. Aurones: A Promising Heterocyclic Scaffold for the Development of Potent Antileishmanial Agents

    PubMed Central

    Roussaki, Marina; Costa Lima, Sofia; Kypreou, Anna-Maria; Kefalas, Panagiotis; Cordeiro da Silva, Anabela; Detsi, Anastasia

    2012-01-01

    A series of (Z)-2-benzylidenebenzofuran-3-(2H)-ones (aurones) bearing a variety of substituents on rings A and B were synthesized and evaluated for their antiparasitic activity against the intracellular amastigote form of Leishmania infantum and their cytotoxicity against human THP1-differentiated macrophages. In general, aurones bearing no substituents on ring A (compounds 4a–4f) exhibit higher toxicity than aurones with 4,6-dimethoxy substitution (compounds 4g–4l). Among the latter, two aurones possessing a 2′-methoxy or a 2′-methyl group (compounds 4i and 4j) exhibit potent antileishmanial activity (IC50 = 1.3 ± 0.1 μM and IC50 = 1.6 ± 0.2 μM, resp.), comparable to the activity of the reference drug Amphotericin B, whereas they present significantly lower cytotoxicity than Amphotericin B as deduced by the higher selectivity index. PMID:25374683

  18. Ohmic contacts for wide bandgap semiconductors: Processing, properties and mechanisms

    NASA Astrophysics Data System (ADS)

    Park, Mi-Ran

    Stable Ohmic contacts are essential for reliable operation of wide bandgap semiconductor electronic and optoelectronic devices. Such contacts have been made to molecular beam epitaxy (MBE) grown n-type and p-type ZnSe on (100) semi-insulating GaAs substrates and metalorganic chemical vapor deposition (MOCVD) grown p-type GaN on (0001) sapphire substrates. Various metals have been deposited by thermal evaporation and annealing techniques at different temperatures. Chemical etching and cleaning, plasma treatment using reactive ion etching (RIE), and cryogenic treatment in liquid nitrogen have been studied. Ion implantation was also performed to obtain highly doped materials. The electrical characteristics for the contacts were examined by the current versus voltage data and the specific contact resistance was determined by use of the transmission line method (TLM) for II-VI n-type and p-type ZnSe and the circular transmission line method (c-TLM) for III-V p-type GaN, respectively. Contacts formed by In/Au to n-type ZnSe and Cu/Au to p-type ZnSe showed the lowest specific contact resistance values of 1.04 x 10--2 Ocm2 and 1.67 x 10--1 Ocm 2, respectively. A nitrogen plasma treatment of the ZnSe surface prior to metallization was proven to lower the contact resistance to p-type ZnSe. Two different current flow mechanisms involving thermionic emission and thermionic field emission were shown for the Cu/Au contact to low doped p-ZnSe (1 x 1017 cm--3) and three involving thermionic emission, thermionic field emission, and tunneling for the Mg/Au contact to highly doped n-ZnSe (1.15 x 1019 cm--3). MOCVD grown p-type Mg-doped GaN with hole concentration of 1.41 x 1017 cm--3 was used to study Ohmic contacts to p-type GaN. The effects of the cryogenic process on improving Ohmic behavior (I-V linearity) and reducing the specific contact resistance were investigated and may result from a combination of the improved surface morphology and the recrystallizing of new compounds such as NiO and Au:Pd solid solution. The I-V-T measurement for both contacts had similar behavior and closely fit thermionic field emission current mechanisms with little deviation but dominant transport mechanisms were not clear since the contacts were practically Ohmic. (Abstract shortened by UMI.)

  19. Cyclic alpha-conotoxin peptidomimetic chimeras as potent GLP-1R agonists.

    PubMed

    Swedberg, Joakim E; Schroeder, Christina I; Mitchell, Justin M; Durek, Thomas; Fairlie, David P; Edmonds, David J; Griffith, David A; Ruggeri, Roger B; Derksen, David R; Loria, Paula M; Liras, Spiros; Price, David A; Craik, David J

    2015-10-20

    Type 2 diabetes mellitus (T2DM) results from compromised pancreatic β-cell function, reduced insulin production, and lowered insulin sensitivity in target organs resulting in hyperglycemia. The GLP-1 hormone has two biologically active forms, GLP-1-(7-37) and GLP-1-(7-36)amide, which are equipotent at the glucagon-like peptide-1 receptor (GLP-1R). These peptides are central both to normal glucose metabolism and dysregulation in T2DM. Several structurally modified GLP-1 analogues are now approved drugs, and a number of other analogues are in clinical trials. None of these compounds is orally bioavailable and all require parenteral delivery. Recently, a number of smaller peptidomimetics containing 11-12 natural and unnatural amino acids have been identified that have similar insulin regulating profiles as GLP-1. The α-conotoxins are a class of disulfide rich peptide venoms isolated from cone snails, and are known for their highly constrained structures and resistance to enzymatic degradation. In this study, we examined whether 11-residue peptidomimetics incorporated into α-conotoxin scaffolds, forming monocyclic or bicyclic compounds constrained by disulfide bonds and/or backbone cyclization, could activate the GLP-1 receptor (GLP-1R). Several compounds showed potent (nanomolar) agonist activity at GLP-1R, as evaluated via cAMP signaling. In addition, HPLC retention times and in silico calculations suggested that mono- and bicyclic compounds had more favorable n-octanol/water partition coefficients according to the virtual partition coefficient model (vLogP), while maintaining a smaller radius of gyration compared to corresponding uncyclized peptidomimetics. Our findings suggest that cyclic peptidomimetics provide a potential avenue for future design of potent, compact ligands targeting GLP-1R and possessing improved physicochemical properties. PMID:26352676

  20. Contact Trees: Network Visualization beyond Nodes and Edges.

    PubMed

    Sallaberry, Arnaud; Fu, Yang-chih; Ho, Hwai-Chung; Ma, Kwan-Liu

    2016-01-01

    Node-Link diagrams make it possible to take a quick glance at how nodes (or actors) in a network are connected by edges (or ties). A conventional network diagram of a "contact tree" maps out a root and branches that represent the structure of nodes and edges, often without further specifying leaves or fruits that would have grown from small branches. By furnishing such a network structure with leaves and fruits, we reveal details about "contacts" in our ContactTrees upon which ties and relationships are constructed. Our elegant design employs a bottom-up approach that resembles a recent attempt to understand subjective well-being by means of a series of emotions. Such a bottom-up approach to social-network studies decomposes each tie into a series of interactions or contacts, which can help deepen our understanding of the complexity embedded in a network structure. Unlike previous network visualizations, ContactTrees highlight how relationships form and change based upon interactions among actors, as well as how relationships and networks vary by contact attributes. Based on a botanical tree metaphor, the design is easy to construct and the resulting tree-like visualization can display many properties at both tie and contact levels, thus recapturing a key ingredient missing from conventional techniques of network visualization. We demonstrate ContactTrees using data sets consisting of up to three waves of 3-month contact diaries over the 2004-2012 period, and discuss how this design can be applied to other types of datasets. PMID:26784350

  1. Ohmic Contact of Au/Mo on Hg1- x Cd x Te

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Lin, Chun; Zhou, Songmin; Hu, Xiaoning

    2016-06-01

    The contact resistance between Au/Mo and HgCdTe was investigated. The influence of thermal annealing on metal-semiconductor contact on short and middle-wavelength HgCdTe is also discussed in this paper. The specific contact resistance ρ c (300 K, 80 K) of Au/Mo/HgCdTe was measured by the transmission line method. Good ohmic contacts can be formed with Au/Mo on long-wavelength infrared p-HgCdTe ( x = 0.23) with a low specific contact resistivity of 3.78E-04 Ωcm2 measured at 80 K. For the mid-wavelength infrared p-HgCdTe ( x = 0.30), the metal-semiconductor contact is ohmic, and the minimum specific contact resistivity of 7.40E-04 Ωcm2 is obtained after annealing at 120°C/10 min. The as-deposited contact between Au/Mo and the short-wavelength infrared HgCdTe ( x = 0.47) shows non-ohmic behavior. After annealing at 120°C/5 min, although the contact behavior is still a Schottky contact, the contact resistance decreases. For the n-HgCdTe ( x = 0.27), the metal-semiconductor contact is ohmic with a specific contact resistivity of 5.70E-04 Ωcm2 at 80 K.

  2. Ohmic Contact of Au/Mo on Hg1-x Cd x Te

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Lin, Chun; Zhou, Songmin; Hu, Xiaoning

    2016-02-01

    The contact resistance between Au/Mo and HgCdTe was investigated. The influence of thermal annealing on metal-semiconductor contact on short and middle-wavelength HgCdTe is also discussed in this paper. The specific contact resistance ρ c (300 K, 80 K) of Au/Mo/HgCdTe was measured by the transmission line method. Good ohmic contacts can be formed with Au/Mo on long-wavelength infrared p-HgCdTe (x = 0.23) with a low specific contact resistivity of 3.78E-04 Ωcm2 measured at 80 K. For the mid-wavelength infrared p-HgCdTe (x = 0.30), the metal-semiconductor contact is ohmic, and the minimum specific contact resistivity of 7.40E-04 Ωcm2 is obtained after annealing at 120°C/10 min. The as-deposited contact between Au/Mo and the short-wavelength infrared HgCdTe (x = 0.47) shows non-ohmic behavior. After annealing at 120°C/5 min, although the contact behavior is still a Schottky contact, the contact resistance decreases. For the n-HgCdTe (x = 0.27), the metal-semiconductor contact is ohmic with a specific contact resistivity of 5.70E-04 Ωcm2 at 80 K.

  3. Computing Contact Stresses In Gear Teeth

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Somprakit, Paisan; Huston, Ronald L.

    1995-01-01

    Improved method of computing contact stresses in gear teeth accounts for complicating effects like those of static and sliding friction. Provides iterative procedure for determination of contact region and nodal contact forces along with contact stresses. Method based on equations and computational procedure incorporating these effects routinely.

  4. Common environmental contact allergens in Singapore.

    PubMed

    Ng, S K

    1990-12-01

    Contact allergens produce three types of reactions. The commonest reaction is allergic contact dermatitis (ACD). The commonest contactants in Singapore causing ACD are, in decreasing order of importance, nickel, fragrances, neomycin, lanolin, colophony, flavine, rubber chemicals, paraphenylenediamine, clioquinol and chromates. Another type of allergic contact reaction is immunologic contact urticaria (ICU). ICU is an IgE mediated mechanisms. Contact allergens causing ICU in Singapore are proteinaceous foodstuffs and rubber latex products. Photoallergic contact dermatitis is occasionally seen in Singapore. The commonest agent is Musk Ambrette, a perfume fixature found in male colognes. PMID:2281361

  5. Contact bubble bilayers with flush drainage.

    PubMed

    Iwamoto, Masayuki; Oiki, Shigetoshi

    2015-01-01

    Planar lipid bilayers have been used to form stable bilayers into which membrane proteins are reconstituted for measurements of their function under an applied membrane potential. Recently, a lipid bilayer membrane is formed by the apposition of two monolayers that line an oil-electrolyte interface. Here, a bilayer membrane system is developed with picoliter bubbles under mechanically and chemically manipulable conditions. A water bubble lined with a phospholipid monolayer is blown from a glass pipette into an oil phase. Two blowing pipettes are manipulated, and bubbles (each with a diameter of ~ 50 μm) are held side by side to form a bilayer, which is termed a contact bubble bilayer. With the electrode implemented in the blowing pipette, currents through the bilayer are readily measured. The intra-bubble pressure is varied with the pressure-controller, leading to various sizes of the bubble and the membrane area. A rapid solution exchange system is developed by introducing additional pressure-driven injection pipettes, and the blowing pipette works as a drain. The solution is exchanged within 20 ms. Also, an asymmetric membrane with different lipid composition of each leaflet is readily formed. Example applications of this versatile method are presented to characterize the function of ion channels. PMID:25772819

  6. Contact Bubble Bilayers with Flush Drainage

    PubMed Central

    Iwamoto, Masayuki; Oiki, Shigetoshi

    2015-01-01

    Planar lipid bilayers have been used to form stable bilayers into which membrane proteins are reconstituted for measurements of their function under an applied membrane potential. Recently, a lipid bilayer membrane is formed by the apposition of two monolayers that line an oil-electrolyte interface. Here, a bilayer membrane system is developed with picoliter bubbles under mechanically and chemically manipulable conditions. A water bubble lined with a phospholipid monolayer is blown from a glass pipette into an oil phase. Two blowing pipettes are manipulated, and bubbles (each with a diameter of ~ 50 μm) are held side by side to form a bilayer, which is termed a contact bubble bilayer. With the electrode implemented in the blowing pipette, currents through the bilayer are readily measured. The intra-bubble pressure is varied with the pressure-controller, leading to various sizes of the bubble and the membrane area. A rapid solution exchange system is developed by introducing additional pressure-driven injection pipettes, and the blowing pipette works as a drain. The solution is exchanged within 20 ms. Also, an asymmetric membrane with different lipid composition of each leaflet is readily formed. Example applications of this versatile method are presented to characterize the function of ion channels. PMID:25772819

  7. Improved Electrical Contact For Dowhhole Drilling Networks

    DOEpatents

    Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron

    2005-08-16

    An electrical contact system for transmitting information across tool joints while minimizing signal reflections that occur at the tool joints includes a first electrical contact comprising an annular resilient material. An annular conductor is embedded within the annular resilient material and has a surface exposed from the annular resilient material. A second electrical contact is provided that is substantially equal to the first electrical contact. Likewise, the second electrical contact has an annular resilient material and an annular conductor. The two electrical contacts configured to contact one another such that the annular conductors of each come into physical contact. The annular resilient materials of each electrical contact each have dielectric characteristics and dimensions that are adjusted to provide desired impedance to the electrical contacts.

  8. What Does It Take to Synergistically Combine Sub-Potent Natural Products into Drug-Level Potent Combinations?

    PubMed Central

    Qin, Chu; Tan, Kai Leng; Zhang, Cun Long; Tan, Chun Yan; Chen, Yu Zong; Jiang, Yu Yang

    2012-01-01

    There have been renewed interests in natural products as drug discovery sources. In particular, natural product combinations have been extensively studied, clinically tested, and widely used in traditional, folk and alternative medicines. But opinions about their therapeutic efficacies vary from placebo to synergistic effects. The important questions are whether synergistic effects can sufficiently elevate therapeutic potencies to drug levels, and by what mechanisms and at what odds such combinations can be assembled. We studied these questions by analyzing literature-reported cell-based potencies of 190 approved anticancer and antimicrobial drugs, 1378 anticancer and antimicrobial natural products, 99 natural product extracts, 124 synergistic natural product combinations, and 122 molecular interaction profiles of the 19 natural product combinations with collective potency enhanced to drug level or by >10-fold. Most of the evaluated natural products and combinations are sub-potent to drugs. Sub-potent natural products can be assembled into combinations of drug level potency at low probabilities by distinguished multi-target modes modulating primary targets, their regulators and effectors, and intracellular bioavailability of the active natural products. PMID:23209627

  9. Novel Gallate Triphenylphosphonium Derivatives with Potent Antichagasic Activity.

    PubMed

    Cortes, Leonel A; Castro, Lorena; Pesce, Bárbara; Maya, Juan D; Ferreira, Jorge; Castro-Castillo, Vicente; Parra, Eduardo; Jara, José A; López-Muñoz, Rodrigo

    2015-01-01

    disease is one of the most neglected tropical diseases in the world, affecting nearly 15 million people, primarily in Latin America. Only two drugs are used for the treatment of this disease, nifurtimox and benznidazole. These drugs have limited efficacy and frequently induce adverse effects, limiting their usefulness. Consequently, new drugs must be found. In this study, we demonstrated the in vitro trypanocidal effects of a series of four gallic acid derivatives characterized by a gallate group linked to a triphenylphosphonium (TPP(+)) moiety (a delocalized cation) via a hydrocarbon chain of 8, 10, 11, or 12 atoms (TPP(+)-C8, TPP(+)-C10, TPP(+)-C11, and TPP(+)-C12, respectively). We analyzed parasite viability in isolated parasites (by MTT reduction and flow cytometry) and infected mammalian cells using T. cruzi Y strain trypomastigotes. Among the four derivatives, TPP(+)-C10 and TPP(+)-C12 were the most potent in both models, with EC50 values (in isolated parasites) of 1.0 ± 0.6 and 1.0 ± 0.7 μM, respectively, and were significantly more potent than nifurtimox (EC50 = 4.1 ± 0.6 μM). At 1 μM, TPP(+)-C10 and TPP(+)-C12 induced markers of cell death, such as phosphatidylserine exposure and propidium iodide permeabilization. In addition, at 1 μM, TPP(+)-C10 and TPP(+)-C12 significantly decreased the number of intracellular amastigotes (TPP(+)-C10: 24.3%, TPP(+)-C12: 19.0% of control measurements, as measured by DAPI staining) and the parasite's DNA load (C10: 10%, C12: 13% of control measurements, as measured by qPCR). Based on the previous mode of action described for these compounds in cancer cells, we explored their mitochondrial effects in isolated trypomastigotes. TPP(+)-C10 and TPP(+)-C12 were the most potent compounds, significantly altering mitochondrial membrane potential at 1 μM (measured by JC-1 fluorescence) and inducing mitochondrial transition pore opening at 5 μM. Taken together, these results indicate that the TPP(+)-C10 and TPP(+)-C12 derivatives of gallic acid are promising trypanocidal agents with mitochondrial activity. PMID:26317199

  10. Novel Gallate Triphenylphosphonium Derivatives with Potent Antichagasic Activity

    PubMed Central

    Cortes, Leonel A.; Castro, Lorena; Pesce, Bárbara; Maya, Juan D.; Ferreira, Jorge; Castro-Castillo, Vicente; Parra, Eduardo; Jara, José A.; López-Muñoz, Rodrigo

    2015-01-01

    Chagas disease is one of the most neglected tropical diseases in the world, affecting nearly 15 million people, primarily in Latin America. Only two drugs are used for the treatment of this disease, nifurtimox and benznidazole. These drugs have limited efficacy and frequently induce adverse effects, limiting their usefulness. Consequently, new drugs must be found. In this study, we demonstrated the in vitro trypanocidal effects of a series of four gallic acid derivatives characterized by a gallate group linked to a triphenylphosphonium (TPP+) moiety (a delocalized cation) via a hydrocarbon chain of 8, 10, 11, or 12 atoms (TPP+-C8, TPP+-C10, TPP+-C11, and TPP+-C12, respectively). We analyzed parasite viability in isolated parasites (by MTT reduction and flow cytometry) and infected mammalian cells using T. cruzi Y strain trypomastigotes. Among the four derivatives, TPP+-C10 and TPP+-C12 were the most potent in both models, with EC50 values (in isolated parasites) of 1.0 ± 0.6 and 1.0 ± 0.7 μM, respectively, and were significantly more potent than nifurtimox (EC50 = 4.1 ± 0.6 μM). At 1 μM, TPP+-C10 and TPP+-C12 induced markers of cell death, such as phosphatidylserine exposure and propidium iodide permeabilization. In addition, at 1 μM, TPP+-C10 and TPP+-C12 significantly decreased the number of intracellular amastigotes (TPP+-C10: 24.3%, TPP+-C12: 19.0% of control measurements, as measured by DAPI staining) and the parasite’s DNA load (C10: 10%, C12: 13% of control measurements, as measured by qPCR). Based on the previous mode of action described for these compounds in cancer cells, we explored their mitochondrial effects in isolated trypomastigotes. TPP+-C10 and TPP+-C12 were the most potent compounds, significantly altering mitochondrial membrane potential at 1 μM (measured by JC-1 fluorescence) and inducing mitochondrial transition pore opening at 5 μM. Taken together, these results indicate that the TPP+-C10 and TPP+-C12 derivatives of gallic acid are promising trypanocidal agents with mitochondrial activity. PMID:26317199

  11. PREFACE: Non-contact AFM Non-contact AFM

    NASA Astrophysics Data System (ADS)

    Giessibl, Franz J.; Morita, Seizo

    2012-02-01

    This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of Kelvin probe force microscopy for Si surfaces by taking account of chemical forces Masaru Tsukada, Akira Masago and Mamoru Shimizu Reversal of atomic contrast in scanning probe microscopy on (111) metal surfaces M Ondrácek, C González and P Jelínek Mechanical properties of H2Pc self-assembled monolayers at the single molecule level by noncontact atomic force microscopy Han-Qing Mao, Na Li, Xi Chen and Qi-Kun Xue High-resolution imaging of C60 molecules using tuning-fork-based non-contact atomic force microscopy R Pawlak, S Kawai, S Fremy, T Glatzel and E Meyer NC-AFM contrast formation on the calcite (101¯4) surface Philipp Rahe, Jens Schütte and Angelika Kühnle Imaging and manipulation of adatoms on an alumina surface by noncontact atomic force microscopy G H Simon, M Heyde and H-J Freund Three-dimensional scanning force/tunneling spectroscopy at room temperature Yoshiaki Sugimoto, Keiichi Ueda, Masayuki Abe and Seizo Morita Imaging and manipulation of the Si(100) surface by small-amplitude NC-AFM at zero and very low applied biasA Sweetman, R Danza, S Gangopadhyay and P Moriarty Manipulation of individual water molecules on CeO2(111) S Torbrügge, O Custance, S Morita and M Reichling FM-AFM imaging of a commercial polyethylene film immersed in n-dodecaneTakumi Hiasa, Tomoki Sugihara, Kenjiro Kimura and Hiroshi Onishi

  12. On the optimization of VLSI contacts

    NASA Astrophysics Data System (ADS)

    Maddox, R. L.

    1985-03-01

    The contact-resistance characteristic of silicon devices has been a subject of research and development since the early days of silicon integrated-circuit technology. The contact-chain losses suffered by very large scale integration (VLSI), however, have made the minimization of contact resistance a critical parameter due to the large number of contacts per circuit and due to the increase of contact resistance with decreasing contact size. This paper will present a brief review of the theory of contact resistance, the literature, measurement techniques, and of the transmission-line model (TLM) for analyzing contact-resistance data. Contact-resistance data pertaining to shallow high-conductivity contacts for VLSI will be presented as a function of the junction parameters (implant dose, etc.) and of the contact area for BF2 and arsenic implants with aluminum-silicon metallization. Contact-resistance data of a sputtered molybdenum silicide contact barrier for boron and arsenic implants versus contact area will also be presented and compared to the aluminum-silicon control samples with a discussion regarding the uniformity of contacts to silicon.

  13. Seating and Grouping Choices: A Chance for Making Contact

    ERIC Educational Resources Information Center

    Lin, Isadora Jung-Hsiu

    2015-01-01

    This paper discusses how international students negotiated their chances for making contact with other students in higher education and how such effort affected their educational experiences in Australia. In the past few decades, international students have formed part of the increasingly diverse multicultural student population in Australian…

  14. Method and apparatus for producing co-current fluid contact

    DOEpatents

    Trutna, William R.

    1997-01-01

    An improved packing system and method are disclosed wherein a packing section includes a liquid distributor and a separator placed above the distributor so that gas rising through the liquid distributor contacts liquid in the distributor, forming a gas-liquid combination which rises in co-current flow to the separator. Liquid is collected in the separator, from which gas rises.

  15. Method and apparatus for producing co-current fluid contact

    DOEpatents

    Trutna, W.R.

    1997-12-09

    An improved packing system and method are disclosed wherein a packing section includes a liquid distributor and a separator placed above the distributor so that gas rising through the liquid distributor contacts liquid in the distributor, forming a gas-liquid combination which rises in co-current flow to the separator. Liquid is collected in the separator, from which gas rises. 13 figs.

  16. Non-contacting techniques for plant drought stress detection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Non-contacting sensing techniques based on plant canopy temperature, plant leaf motion, and plant canopy reflectance were evaluated for drought stress detection using New Guinea Impatiens as a model plant. The performances of Crop Water Stress Index (CWSI), plant motion in the form of Covariance of ...

  17. Allergic contact dermatitis in dentistry.

    PubMed

    Rubel, D M; Watchorn, R B

    2000-05-01

    Allergic contact dermatitis (ACD) in dentistry may affect dentists and orthodontists, technicians, nurses and patients. Changes to dental practice in recent years have altered the reported frequencies of allergens causing ACD in both dental personnel and patients. Allergic contact dermatitis to medicaments, metals and glutaraldehyde were previously common allergens in dentistry; however, widespread adoption of rubber gloves by staff has resulted in a significant increase in ACD to glove allergens in both dental staff and their patients, while affording protection against the traditional allergens. Both public concerns about potential toxicity of metals in oral restorations and a greater demand for cosmetic dentistry, have resulted in greater use of acrylics and resins by dental personnel, exposing them to highly allergenic materials. Dermatologists need to be aware of the newer allergenic materials used in dentistry in order to correctly manage skin diseases in this high-risk group. PMID:10812698

  18. Contact microscopy with synchrotron radiation

    SciTech Connect

    Panessa-Warren, B.J.

    1985-10-01

    Soft x-ray contact microscopy with synchrotron radiation offers the biologist and especially the microscopist, a way to morphologically study specimens that could not be imaged by conventional TEM, STEM or SEM methods (i.e. hydrated samples, samples easily damaged by an electron beam, electron dense samples, thick specimens, unstained low contrast specimens) at spatial resolutions approaching those of the TEM, with the additional possibility to obtain compositional (elemental) information about the sample as well. Although flash x-ray sources offer faster exposure times, synchrotron radiation provides a highly collimated, intense radiation that can be tuned to select specific discrete ranges of x-ray wavelengths or specific individual wavelengths which optimize imaging or microanalysis of a specific sample. This paper presents an overview of the applications of x-ray contact microscopy to biological research and some current research results using monochromatic synchrotron radiation to image biological samples. 24 refs., 10 figs.

  19. Remedial Action Contacts Directory - 1997

    SciTech Connect

    1997-05-01

    This document, which was prepared for the US Department of Energy (DOE) Office of Environmental Restoration (ER), is a directory of 2628 individuals interested or involved in environmental restoration and/or remedial actions at radioactively contaminated sites. This directory contains a list of mailing addresses and phone numbers of DOE operations, area, site, project, and contractor offices; an index of DOE operations, area, site, project, and contractor office sorted by state; a list of individuals, presented by last name, facsimile number, and e-mail address; an index of affiliations presented alphabetically, with individual contacts appearing below each affiliation name; and an index of foreign contacta sorted by country and affiliation. This document was generated from the Remedial Action Contacts Database, which is maintained by the Remedial Action Program Information Center (RAPIC).

  20. Freely suspended quantum point contacts

    NASA Astrophysics Data System (ADS)

    Rössler, C.; Herz, M.; Bichler, M.; Ludwig, S.

    2010-05-01

    We present a versatile design of freely suspended quantum point contacts with particular large one-dimensional subband quantization energies of up to Δɛ≈10 meV. The nanoscale bridges embedding a two-dimensional electron system are fabricated from AlGaAs/GaAs heterostructures by electron-beam lithography and etching techniques. Narrow constrictions define quantum point contacts that are capacitively controlled via local in-plane side gates. Employing transport spectroscopy, we investigate the transition from electrostatic subbands to Landau quantization in a perpendicular magnetic field. The large subband quantization energies allow us to utilize a wide magnetic field range and thereby observe a large exchange split spin-gap of the two lowest Landau-levels.

  1. Allergic contact dermatitis from grasses.

    PubMed

    Koh, D; Goh, C L; Tan, H T; Ng, S K; Wong, W K

    1997-07-01

    This study attempts to demonstrate the existence of allergic contact dermatitis from grass, and to develop a patch test series to screen patients with grass intolerance. 6 common grass species from lawns and military training areas were collected. Solvent extracts of polar, non-polar and volatile fractions were prepared and used for patch testing in 20 control subjects and 46 patients with a history of grass intolerance. The 20 controls had negative responses to patch testing. 5 out of 46 patients had positive patch tests to Axonopus compressus (carpet grass), Ischaemum muticum (seashore centipede grass), Imperata cylindrica (lalang), Panicum maximum (Guinea grass) and Pennisetum purpureum (elephant grass). Reactions to the non-polar fraction for all 5 species were noted. This study demonstrates the existence of allergic contact dermatitis from various common species of grass. In our series, this is seen in 11% of those with a history of grass intolerance. PMID:9255483

  2. Sensing with superconducting point contacts.

    PubMed

    Nurbawono, Argo; Zhang, Chun

    2012-01-01

    Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors. PMID:22778630

  3. Allergic contact dermatitis from carmine.

    PubMed

    Shaw, Daniel W

    2009-01-01

    A 28-year-old woman developed allergic contact dermatitis within 6 to 24 hours exclusively after using carmine-containing eyeshadows and lipsticks. She had both a positive patch test result and a positive antecubital repeated open application test result with carmine 2.5% in petrolatum. Thirty other patients had negative patch test results. Carmine is a widely used pigment derived from gravid cochineal insects. Carminic acid is the source of its color. Only two previous publications describing allergic contact dermatitis from carmine could be found. The ingredient in carmine causing these delayed hypersensitivity reactions has not been studied. In contrast, there are numerous reports of immediate hypersensitivity reactions from carmine, mostly from its use in foods and beverages but also from cosmetics and pharmaceuticals. These are immunoglobulin E-mediated reactions directed against cochineal proteins. PMID:19808007

  4. Sensing with Superconducting Point Contacts

    PubMed Central

    Nurbawono, Argo; Zhang, Chun

    2012-01-01

    Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors. PMID:22778630

  5. Contact charge-transfer lasers

    SciTech Connect

    Dharamsi, A.N.; Tulip, J.

    1981-07-01

    A mechanism for sustaining population inversions in contact charge-transfer complexes in which the ground electronic state is not bound is described. The mechanism relies on picosecond radiationless depletion of the lower laser state. This generates an inversion even when the ground-state potential curve, as plotted against the donor-acceptor distance, is not repulsive vertically below the excited state minimum. Contact charge-transfer lasers would offer high gain, high-energy density, and tunable sources of coherent radiation in the uv and visible. A method for pumping such a laser is examined and applied to the pyrrole-oxygen complex. A rate equation analysis is done and estimates for gain and energy density are presented.

  6. Contact | Office of Cancer Genomics

    Cancer.gov

    For more information about the Office of Cancer Genomics, please contact: Office of Cancer Genomics National Cancer Institute 31 Center Drive, 10A07 Bethesda, Maryland 20892-2580 Phone: (301) 451-8027 Fax: (301) 480-4368 Email: ocg@mail.nih.gov *Please note that this site will not function properly in Internet Explorer unless you completely turn off the Compatibility View*

  7. Discovery of Potent and Reversible Monoacylglycerol Lipase Inhibitors

    PubMed Central

    King, Alvin R.; Dotsey, Emmanuel Y.; Lodola, Alessio; Jung, Kwang Mook; Ghomian, Azar; Qiu, Yan; Fu, Jin; Mor, Marco; Piomelli, Daniele

    2011-01-01

    Summary Monoacylglycerol lipase (MGL) is a serine hydrolase involved in the biological deactivation of the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG). Previous efforts to design MGL inhibitors have focused on chemical scaffolds that irreversibly block the activity of this enzyme. Here, we describe two naturally occurring terpenoids, pristimerin and euphol, which inhibit MGL activity with high potency (median effective concentration, IC50 = 93 nM and 315 nM, respectively) through a reversible mechanism. Mutational and modeling studies suggest that the two agents occupy a common hydrophobic pocket located within the putative lid domain of MGL, and each reversibly interact with one of two adjacent cysteine residues (Cys201 and Cys208) flanking such pocket. This previously unrecognized regulatory region may offer a novel molecular target for potent and reversible inhibitors of MGL. PMID:19875078

  8. Deorphaning pyrrolopyrazines as potent multi-target antimalarial agents.

    PubMed

    Reker, Daniel; Seet, Michael; Pillong, Max; Koch, Christian P; Schneider, Petra; Witschel, Matthias C; Rottmann, Matthias; Freymond, Cline; Brun, Reto; Schweizer, Bernd; Illarionov, Boris; Bacher, Adelbert; Fischer, Markus; Diederich, Franois; Schneider, Gisbert

    2014-07-01

    The discovery of pyrrolopyrazines as potent antimalarial agents is presented, with the most effective compounds exhibiting EC50 values in the low nanomolar range against asexual blood stages of Plasmodium falciparum in human red blood cells, and Plasmodium berghei liver schizonts, with negligible HepG2 cytotoxicity. Their potential mode of action is uncovered by predicting macromolecular targets through avant-garde computer modeling. The consensus prediction method suggested a functional resemblance between ligand binding sites in non-homologous target proteins, linking the observed parasite elimination to IspD, an enzyme from the non-mevalonate pathway of isoprenoid biosynthesis, and multi-kinase inhibition. Further computational analysis suggested essential P. falciparum kinases as likely targets of our lead compound. The results obtained validate our methodology for ligand- and structure-based target prediction, expand the bioinformatics toolbox for proteome mining, and provide unique access to deciphering polypharmacological effects of bioactive chemical agents. PMID:24895172

  9. A new potent teratogen in CD rats inducing cleft palate.

    PubMed

    Shibata, M

    1993-08-01

    The teratogenic potential of cis-1-[4-(p-menthane-8-yloxy)phenyl] [corrected] piperidine (YM9429) was evaluated using CD (SD) rats. YM9429 induced cleft palate and specific skeletal variations including accessory cervical and lumbar ribs or excessive formation of the 7th lumbar vertebra by oral treatment during the organogenetic periods. No visceral or external malformations were induced, and no embryo/fetal mortality or fetal growth retardation was observed. Maternal plasma biochemical examination revealed decreases of cholesterol and phospholipid levels during days 15-17 of pregnancy after the treatment. The results suggest that YM9429 is a potent and specific teratogen inducing cleft palate in CD rats, and the reduced maternal plasma levels of cholesterol and phospholipid during the period of palatine closure are related to the induction of cleft palate. PMID:8246309

  10. A Potent and Site-Selective Agonist of TRPA1.

    PubMed

    Takaya, Junichiro; Mio, Kazuhiro; Shiraishi, Takuya; Kurokawa, Tatsuki; Otsuka, Shinya; Mori, Yasuo; Uesugi, Motonari

    2015-12-23

    TRPA1 is a member of the transient receptor potential (TRP) cation channel family that is expressed primarily on sensory neurons. This chemosensor is activated through covalent modification of multiple cysteine residues with a wide range of reactive compounds including allyl isothiocyanate (AITC), a spicy component of wasabi. The present study reports on potent and selective agonists of TRPA1, discovered through screening 1657 electrophilic molecules. In an effort to validate the mode of action of hit molecules, we noted a new TRPA1-selective agonist, JT010 (molecule 1), which opens the TRPA1 channel by covalently and site-selectively binding to Cys621 (EC50 = 0.65 nM). The results suggest that a single modification of Cys621 is sufficient to open the TRPA1 channel. The TRPA1-selective probe described herein might be useful for further mechanistic studies of TRPA1 activation. PMID:26630251

  11. Development of potent inhibitors of the coxsackievirus 3C protease

    SciTech Connect

    Lee, Eui Seung; Lee, Won Gil; Yun, Soo-Hyeon; Rho, Seong Hwan; Im, Isak; Yang, Sung Tae; Sellamuthu, Saravanan; Lee, Yong Jae; Kwon, Sun Jae; Park, Ohkmae K.; Jeon, Eun-Seok; Park, Woo Jin . E-mail: wjpark@gist.ac.kr; Kim, Yong-Chul . E-mail: yongchul@gist.ac.kr

    2007-06-22

    Coxsackievirus B3 (CVB3) 3C protease (3CP) plays essential roles in the viral replication cycle, and therefore, provides an attractive therapeutic target for treatment of human diseases caused by CVB3 infection. CVB3 3CP and human rhinovirus (HRV) 3CP have a high degree of amino acid sequence similarity. Comparative modeling of these two 3CPs revealed one prominent distinction; an Asn residue delineating the S2' pocket in HRV 3CP is replaced by a Tyr residue in CVB3 3CP. AG7088, a potent inhibitor of HRV 3CP, was modified by substitution of the ethyl group at the P2' position with various hydrophobic aromatic rings that are predicted to interact preferentially with the Tyr residue in the S2' pocket of CVB3 3CP. The resulting derivatives showed dramatically increased inhibitory activities against CVB3 3CP. In addition, one of the derivatives effectively inhibited the CVB3 proliferation in vitro.

  12. Potent Insulin Secretagogue from Scoparia dulcis Linn of Nepalese Origin.

    PubMed

    Sharma, Khaga Raj; Adhikari, Achyut; Hafizur, Rahman M; Hameed, Abdul; Raza, Sayed Ali; Kalauni, Surya Kant; Miyazaki, Jun-Ichi; Choudhary, M Iqbal

    2015-10-01

    Ethno-botanical inspired isolation from plant Scoparia dulcis Linn. (Sweet Broomweed) yielded six compounds, coixol (1), glutinol (2), glutinone (3), friedelin (4), betulinic acid (5), and tetratriacontan-1-ol (6). There structures were identified using mass and 1D- and 2D-NMR spectroscopy techniques. Compounds 1-6 were evaluated for their insulin secretory activity on isolated mice islets and MIN-6 pancreatic β-cell line, and compounds 1 and 2 were found to be potent and mildly active, respectively. Compound 1 was further evaluated for insulin secretory activity on MIN-6 cells. Compound 1 was subjected to in vitro cytotoxicity assay against MIN-6, 3T3 cell lines, and islet cells, and in vivo acute toxicity test in mice that was found to be non-toxic. The insulin secretory activity of compounds 1 and 2 supported the ethno-botanic uses of S. dulcis as an anti-diabetic agent. PMID:26178652

  13. New Conjugates of Quinoxaline as Potent Antitubercular and Antibacterial Agents

    PubMed Central

    Kuppusamy, Rajendran; Killi, Sunil Kumar; Reddy, Y. Padmanabha

    2016-01-01

    Considering quinoxaline as a privileged structure for the design of potent intercalating agents, some new sugar conjugates of quinoxaline were synthesized and characterized by IR, 1HNMR, 13C NMR, and mass spectral data. In vitro testing for antitubercular and antimicrobial activities was performed against Mycobacterium tuberculosis H37Rv and some pathogenic bacteria. Results revealed that conjugate containing ribose moiety demonstrated the most promising activity against Mycobacteria and bacteria with minimum inhibitory concentrations (MIC) of 0.65 and 2.07 μM, respectively. Other conjugates from xylose, glucose, and mannose were moderately active whilst disaccharides conjugates were found to be less active. In silico docking analysis of prototype compound revealed that ATP site of DNA gyrase B subunit could be a possible site for inhibitory action of these synthesized compounds. PMID:27051530

  14. Carbostyril derivatives having potent beta-adrenergic agonist properties.

    PubMed

    Milecki, J; Baker, S P; Standifer, K M; Ishizu, T; Chida, Y; Kusiak, J W; Pitha, J

    1987-09-01

    Derivatives carrying a substituent in the para position of the phenyl group of 8-hydroxy-5-[2-[(1-phenyl-2-methylprop-2-yl)amino]-1-hydroxyethyl] carbostyril (10) were prepared and their effects on beta-adrenoceptors evaluated in vitro. Unsubstituted compound 10, iodo 11, amino 12, and bromoacetamido 13 derivatives (all racemic) bound to the receptor with 15-100-fold lower dissociation constants than that of (-)-isoproterenol. All the above compounds stimulated adenylate cyclase more potently than (-)-isoproterenol. The intrinsic activities of compounds 10 and 12 were equal to that of (-)-isoproterenol. The intrinsic activities of compounds 11 and 13 were 1.3 and 1.2 times that of (-)-isoproterenol, respectively. Treatment of membrane preparations with bromoacetamido derivative 13 resulted in an irreversible loss of binding sites, and thus, 13 seems to be an alkylating affinity label for beta-adrenoceptors. PMID:2887658

  15. Guaiane sesquiterpenes from Biscogniauxia nummularia featuring potent antigerminative activity.

    PubMed

    Amand, Séverine; Langenfeld, Aude; Blond, Alain; Dupont, Joëlle; Nay, Bastien; Prado, Soizic

    2012-04-27

    Xylaranone, a previously unreported guaiane sesquiterpene along with the known terpenoid xylaranol B and the two mellein derivatives 3,5-dimethyl-8-methoxy-3,4-dihydroisocoumarin and 3,5-dimethyl-8-hydroxy-3,4-dihydroisocoumarin were isolated from Biscogniauxia nummularia. Pogostol was also isolated from this fungus, and in light of our spectroscopic data, its structure was revised and corrected. This fungus, which was isolated as an endophyte from the plum yew Cephalotaxus harringtonia, is also suspected of being a pathogen. Interestingly, we report here the potent antigerminative activity of xylaranone and xylaranol B against seeds of Raphanus sativus at concentrations comparable to glyphosate, a commonly used herbicide. This effect suggests a role for these metabolites in the latent fungal pathogenesis of B. nummularia. PMID:22486738

  16. Cystobactamids: myxobacterial topoisomerase inhibitors exhibiting potent antibacterial activity.

    PubMed

    Baumann, Sascha; Herrmann, Jennifer; Raju, Ritesh; Steinmetz, Heinrich; Mohr, Kathrin I; Httel, Stephan; Harmrolfs, Kirsten; Stadler, Marc; Mller, Rolf

    2014-12-22

    The development of new antibiotics faces a severe crisis inter?alia owing to a lack of innovative chemical scaffolds with activities against Gram-negative and multiresistant pathogens. Herein, we report highly potent novel antibacterial compounds, the myxobacteria-derived cystobactamids 1-3, which were isolated from Cystobacter sp. and show minimum inhibitory concentrations in the low ?g?mL(-1) range. We describe the isolation and structure elucidation of three congeners as well as the identification and annotation of their biosynthetic gene cluster. By studying the self-resistance mechanism in the natural producer organism, the molecular targets were identified as bacterial type?IIa topoisomerases. As quinolones are largely exhausted as a template for new type II topoisomerase inhibitors, the cystobactamids offer exciting alternatives to generate novel antibiotics using medicinal chemistry and biosynthetic engineering. PMID:25510965

  17. Subleading contributions to the three-nucleon contact interaction

    SciTech Connect

    Girlanda, L.; Kievsky, A.; Viviani, M.

    2011-07-15

    We obtain a minimal form of the two-derivative three-nucleon contact Lagrangian, by imposing all constraints deriving from discrete symmetries, Fierz identities, and Poincare covariance. The resulting interaction, depending on 10 unknown low-energy constants, leads to a three-nucleon potential which we give in a local form in configuration space. We also consider the leading (no-derivative) four-nucleon interaction and show that there exists only one independent operator.

  18. Plasmons in metal contacted graphene

    NASA Astrophysics Data System (ADS)

    Jadidi, M. M.; Suchkov, A. B.; Myers-Ward, R. L.; Boyd, A. K.; Daniels, K. M.; Gaskill, D. K.; Drew, H. D.; Murphy, T. E.

    2015-03-01

    Subwavelength graphene structures exhibit standing-wave plasmon resonances throughout the terahertz spectral range that can be tuned by application of a gate voltage. These features make graphene an attractive candidate for a variety of electrically tunable terahertz devices, including filters, sensors, sources, and modulators. Plasmonic modes have been observed and analyzed in finite-size graphene elements such as ribbons and disks. However, nearly all optoelectronic applications require electrical connection to the graphene element, which drastically alters the plasmonic boundary conditions and mode structure. We present a study of the effects of conductive electrical contacts on the plasmonic modes of a graphene channel, and examine how the contacts affect the coupling to and from free-space radiation. We show that radiation effects are essential in defining and understanding the properties and linewidths of these modes. We also study how the graphene plasmon mode interacts with the antenna modes of the contacts. These results provide valuable insight for designing antenna-coupled graphene plasmonic devices, including detectors and emitters. This work was sponsored by the US ONR (N000141310865) and the US NSF (ECCS 1309750).

  19. RS 30026: a potent and effective calcium channel agonist.

    PubMed Central

    Patmore, L.; Duncan, G. P.; Clarke, B.; Anderson, A. J.; Greenhouse, R.; Pfister, J. R.

    1990-01-01

    1. A series of dihydropyridine derivatives has been evaluated for calcium channel agonist activity using reversal of nisoldipine-induced inhibition of beating of aggregates of embryonic chick myocytes. This test appears to be specific for calcium channel agonists since isoprenaline and cardiac glycosides are inactive. 2. RS 30026 was the most potent of the series, was significantly more potent than CGP 28392 and of similar potency to Bay K 8644 (pEC50 = 7.45, 6.16 and 7.20, respectively). RS 30026 increased edge movement of individual aggregates, in the absence of nisoldipine, by 50% at 2 nM. 3. Compounds were also evaluated for their effects on guinea-pig papillary muscle and porcine coronary artery rings. RS 30026 displayed positive inotropism at concentrations between 10(-9) and 10(-6) M (pEC200 = 8.21), but was a much more powerful inotrope than Bay K 8644, increasing contractility to 1300% of control at 10(-6) M (compared to 350% of control for Bay K 8644). RS 30026 caused vasoconstriction at concentrations between 10(-10) and 10(-7) M. 4. Calcium channel currents in single embryonic chick myocytes were recorded by whole-cell voltage clamp techniques. RS 30026 (100 nM-500 nM) produced large increases in peak current amplitude and shifted the voltage for threshold and maximal currents to more negative values. RS 30026 (500 nM) also produced large increases in the inward tail currents evoked upon repolarization. The effects of Bay K 8644 (50 and 500 nM) were much less marked.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1694461

  20. Polyoxometalates--potent and selective ecto-nucleotidase inhibitors.

    PubMed

    Lee, Sang-Yong; Fiene, Amelie; Li, Wenjin; Hanck, Theodor; Brylev, Konstantin A; Fedorov, Vladimir E; Lecka, Joanna; Haider, Ali; Pietzsch, Hans-Jürgen; Zimmermann, Herbert; Sévigny, Jean; Kortz, Ulrich; Stephan, Holger; Müller, Christa E

    2015-01-15

    Polyoxometalates (POMs) are inorganic cluster metal complexes that possess versatile biological activities, including antibacterial, anticancer, antidiabetic, and antiviral effects. Their mechanisms of action at the molecular level are largely unknown. However, it has been suggested that the inhibition of several enzyme families (e.g., phosphatases, protein kinases or ecto-nucleotidases) by POMs may contribute to their pharmacological properties. Ecto-nucleotidases are cell membrane-bound or secreted glycoproteins involved in the hydrolysis of extracellular nucleotides thereby regulating purinergic (and pyrimidinergic) signaling. They comprise four distinct families: ecto-nucleoside triphosphate diphosphohydrolases (NTPDases), ecto-nucleotide pyrophosphatases/phosphodiesterases (NPPs), alkaline phosphatases (APs) and ecto-5'-nucleotidase (eN). In the present study, we evaluated the inhibitory potency of a series of polyoxometalates as well as chalcogenide hexarhenium cluster complexes at a broad range of ecto-nucleotidases. [Co4(H2O)2(PW9O34)2](10-) (5, PSB-POM142) was discovered to be the most potent inhibitor of human NTPDase1 described so far (Ki: 3.88 nM). Other investigated POMs selectively inhibited human NPP1, [TiW11CoO40](8-) (4, PSB-POM141, Ki: 1.46 nM) and [NaSb9W21O86](18-) (6, PSB-POM143, Ki: 4.98 nM) representing the most potent and selective human NPP1 inhibitors described to date. [NaP5W30O110](14-) (8, PSB-POM144) strongly inhibited NTPDase1-3 and NPP1 and may therefore be used as a pan-inhibitor to block ATP hydrolysis. The polyoxoanionic compounds displayed a non-competitive mechanism of inhibition of NPPs and eN, but appeared to be competitive inhibitors of TNAP. Future in vivo studies with selected inhibitors identified in the current study are warranted. PMID:25449596

  1. Development of a potent and selective GPR7 (NPBW1) agonist: a systematic structure-activity study of neuropeptide B.

    PubMed

    Kanesaka, Maki; Matsuda, Masao; Hirano, Atsushi; Tanaka, Kenichi; Kanatani, Akio; Tokita, Shigeru

    2007-06-01

    Neuropeptide B (NPB) has been recently identified as an endogenous ligand for GPR7 (NPBW1) and GPR8 (NPBW2) and has been shown to possess a relatively high selectivity for GPR7. In order to identify useful experimental tools to address physiological roles of GPR7, we synthesized a series of NPB analogs based on modification of an unbrominated form of 23 amino acids with amidated C-terminal, Br(-)NPB-23-NH(2). We confirmed that truncation of the N-terminal Trp residue resulted in almost complete loss of the binding affinity of NPB for GPR7 and GPR8, supporting the special importance of this residue for binding. Br(-)NPB-23-NH2 analogs in which each amino acid in positions 4, 5, 7, 8, 9, 10, 12 and 21 was replaced with alanine or glycine exhibited potent binding affinity comparable to the parent peptide. In contrast, replacement of Tyr(11) with alanine reduced the binding affinity for both GPR7 and GPR8 four fold. Of particular interest, several NPB analogs in which the consecutive amino acids from Pro4 to Val(13) were replaced with several units of 5-aminovaleric acid (Ava) linkers retained their potent affinity for GPR7. Furthermore, these Ava-substituted NPB analogs exhibited potent agonistic activities for GPR7 expressed in HEK293 cells. Among the Ava-substituted NPB analogs, analog 15 (Ava-5) and 17 (Ava-3) exhibited potency comparable to the parent peptide for GPR7 with significantly reduced activity for GPR8, resulting in high selectivity for GPR7. These highly potent and selective NPB analogs may be useful pharmacological tools to investigate the physiological and pharmacological roles of GPR7. PMID:17486669

  2. Transdermal eperisone elicits more potent and longer-lasting muscle relaxation than oral eperisone.

    PubMed

    Yang, Sang-In; Park, Ha-Young; Lee, Sang-Ho; Lee, Seung-Jin; Han, Ok-Yeun; Lim, Sung-Cil; Jang, Choon-Gon; Lee, Wan-Suk; Shin, Young-Hee; Kim, Jung-Ju; Lee, Seok-Yong

    2004-07-01

    Eperisone hydrochloride is widely used for the treatment of plasticity to relieve muscle stiffness and back pain. However, oral eperisone has a very low bioavailability and short muscle relaxant activity, because of the profound intestinal first-pass metabolism. To improve the efficacy and compliance of eperisone, we designed a new dosage form, a transdermal patch, and evaluated the efficacy of the eperisone patch with the muscle relaxant activity of rats. The muscle relaxant activity was assessed by the measurement of forelimb grip strength and hanging test in rats. The transdermal patch of eperisone showed significantly enhanced muscle relaxant activity at 0.5 1.5 and 3 cm2/200 g rat (1.39, 4.17 and 8.33 mg of eperisone hydrochloride/kg, respectively) in a dose-dependent manner and the effects lasted over 24 h. Even though oral eperisone hydrochloride showed significant muscle relaxant activity at 12.5, 25 and 50 mg/kg in a dose-dependent manner, the activity lasted only 1 or 2 h after administration. These results suggest that eperisone as transdermal patch form showed efficient absorption with more potent and longer-lasting muscle relaxant activity than oral solution. The transdermal patch form of eperisone will increase the efficacy and compliance in the clinical use of eperisone. PMID:15161997

  3. Biomimetic Design Results in a Potent Allosteric Inhibitor of Dihydrodipicolinate Synthase from Campylobacter jejuni.

    PubMed

    Skovpen, Yulia V; Conly, Cuylar J T; Sanders, David A R; Palmer, David R J

    2016-02-17

    Dihydrodipicolinate synthase (DHDPS), an enzyme required for bacterial peptidoglycan biosynthesis, catalyzes the condensation of pyruvate and β-aspartate semialdehyde (ASA) to form a cyclic product which dehydrates to form dihydrodipicolinate. DHDPS has, for several years, been considered a putative target for novel antibiotics. We have designed the first potent inhibitor of this enzyme by mimicking its natural allosteric regulation by lysine, and obtained a crystal structure of the protein-inhibitor complex at 2.2 Å resolution. This novel inhibitor, which we named "bislysine", resembles two lysine molecules linked by an ethylene bridge between the α-carbon atoms. Bislysine is a mixed partial inhibitor with respect to the first substrate, pyruvate, and a noncompetitive partial inhibitor with respect to ASA, and binds to all forms of the enzyme with a Ki near 200 nM, more than 300 times more tightly than lysine. Hill plots show that the inhibition is cooperative, indicating that the allosteric sites are not independent despite being located on opposite sides of the protein tetramer, separated by approximately 50 Å. A mutant enzyme resistant to lysine inhibition, Y110F, is strongly inhibited by this novel inhibitor, suggesting this may be a promising strategy for antibiotic development. PMID:26836694

  4. On the Modeling of Hydrophobic Contact Angles on Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Patankar, Neelesh

    2002-11-01

    The apparent contact angle of a drop on a rough surface is often modeled using either Wenzel's or Cassie's formulas. Previous experiments are not conclusive regarding which formula to use and when. This information is critical in designing a superhydrophobic substrate for applications in microscale devices. A drop on a rough substrate can occupy multiple equilibrium states. These equilibrium states denote respective local minima in energy. The particular shape that a drop attains depends on how the drop is formed. We propose a design procedure to develop a rough superhydrophobic substrate that accounts for the multiple equilibrium drop shapes. The theory is expected to work well to maximize the advancing contact angle of a drop. It is noted in the end that appropriate models for the receding contact angles on rough substrate must be investigated further before appropriate design procedures, that will maximize the receding contact angle or minimize hysteresis (i.e. minimize the difference between the advancing and receding contact angles), are developed. We discuss a model for the receding contact angle based on the limited data in literature.

  5. Heat transfer at nanoscale contacts investigated with scanning thermal microscopy

    NASA Astrophysics Data System (ADS)

    Assy, Ali; Gomès, Séverine

    2015-07-01

    This article investigates heat transfer at nanoscale contacts through scanning thermal microscopy (SThM) under vacuum conditions. Measurements were performed using two types of resistive SThM probes operating in active mode on germanium and silicon samples. The experiments measure the heat transfer through the nanoscale point contacts formed between the probe apex, platinum-rhodium alloy, or silicon nitride depending on the probe used, and the samples. The thermal resistance at the probe apex-sample interface becomes extremely important as the contact size becomes smaller or comparable to the phonon mean free path within the materials in contact. This resistance is derived from the measurements using a nanoconstriction model. Consistent to what is expected, the interfacial thermal resistance is found to be dependent on the tip and sample. Assuming perfect interfaces, the thermal boundary resistance Rb is determined for the different contacts. Results obtained for Rb range from 10-9 m2 K W-1 up to 14 × 10-9 m2 K W-1 and have the same order of magnitude of values previously published for other materials. The determination of the averaged phonon transmission coefficient t from the data is discussed, and coefficients t for the Si3N4/Ge and Si3N4/Si contacts are estimated based on the diffuse mismatch model (tSi3N4/Ge = 0.5 and tSi3N4/Si = 0.9).

  6. Thermal conductance of a pressed Al-Al contact

    NASA Astrophysics Data System (ADS)

    Wanner, M.

    1981-01-01

    Thermal conductance of a screw-fastened joint between two blocks of Al-alloys has been measured. An AlMg4.5Mn-block, the end of which is cooled by liquid helium, constitutes the upper part of the sample and the contact is formed at the face surface of a cylindrical extension of that block onto which a cylinder, made of AlMgSi1, is pressed by means of a copper-nickel screw. Pressing of the contact was carried out at room temperature by applying a defined torque, M, to the fastening screw. Three samples of the same shape but with differently treated surfaces of contact (machined flat, electro-chemically polished, with gold plated contacts) were studied. The results showed that the machined flat surfaces yield the best contact and that the contact conductance (measured in the range 4.2 K to 1.8 K) of all samples increased with increasing torque. In addition to thermal measurements, a study of the electrical conductance would be very interesting to determine the different contributions of phonon and electron heat conduction by means of the Wiedemann-Franz law. The work is useful for the GIRL (German Infra-Red Laboratory) space experiment.

  7. Exploring Mesoscale Contact Mechanics by Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Buzio, Renato

    Mesoscale contact junctions, formed by mechanical interaction of elastic, viscoelastic, and elastoplastic solids, play a crucial role in a wide range of physical phenomena, going from rubber friction and adhesion to biological adhesion in filamentary attachment pads and cell adhesion and interaction with physical scaffolds. Moreover, they affect the response of several microelectromechanical systems and impact the performance of novel lithographies that manipulate objects, pattern surfaces, and transfer molecules with nanoscale accuracy. It is well known that the behavior of contact spots is highly complex since it depends on different factors, namely, contact geometry, bulk and surface (visco)elasticity, plasticity, physical and chemical adhesion. The introduction of novel experimental strategies, aimed to tightly correlate the junction response with their relevant interfacial properties, is certainly mandatory and highly promising. In this chapter, we present atomic force microscopy as an ideal tool for contact mechanics investigations on individual and multiple contact junctions. In particular, we focus on the fabrication of custom probes, with characteristic size from a few hundred nanometers to several microns, and on their use in nanoindentation studies. We also discuss paradigmatic experiments addressing the role of interfacial roughness, viscoelasticity, plasticity, and adhesion on the mechanical response of mesoscale contacts.

  8. Process for fabricating a wraparound contact solar cell

    SciTech Connect

    Minahan, J.A.; Ralph, E.L.; Dill, H.G.

    1986-09-09

    A process is described for fabricating a wraparound contact solar cell comprising: (a) providing a silicon substrate of a chosen size and shape having first and second opposed major surfaces, (b) forming openings in the substrate and extending through the substrate form the first major surface thereof to the second major surface and spaced apart by a desired lateral dimension of a solar cell, (c) processing the substrate to form a p-n junction therein and between the openings, whereby the vertical walls of the substrate defining the openings are exposed for oxidation, photolithography, and junction-forming steps, (d) utilizing these steps in paragraph (c) above to also form p-region and n-region contacts on the major surfaces of the substrate and extending to a single one of the first and second major surfaces thereof through the openings where they are electrically isolated for bonding to a common solar cell support member, and (e) forming grid lines on one major surface of the substrate for interconnection to one of the p- or n-region contacts for deriving a solar cell output voltage resulting from charge carriers generated at the p-n junction.

  9. Ohmic contacts for high power LEDs

    NASA Astrophysics Data System (ADS)

    Jang, Ho Won; Kim, Jong Kyu; Kim, Soo Young; Yu, Hak Ki; Lee, Jong-Lam

    2004-09-01

    We report novel metallization schemes of transparent p-ohmic contacts for conventional LEDs and reflective p-ohmic contacts for flip-chip and vertical-structure LEDs. Thermally stable and low-resistivity Ru/Ni/ITO ohmic contacts on p-type GaN resulted in the low contact resistivity of 2 × 10-4 cm2 and the high transmittance of 92% at 470 nm wavelength. The light output power of the LED with the Ru/Ni/ITO p-contact was increased by 50% compared to the LED of a Ni/Au transparent p-contact. Using a newly developed Ni/Ag/Ru/Ni/Au reflective p-ohmic contact, the low contact resistivity of 5 × 10-5 cm2 could be achieved. The light reflectance of the contact was as high as 90% at 470 nm wavelength.

  10. Implicit Multibody Penalty-BasedDistributed Contact.

    PubMed

    Xu, Hongyi; Zhao, Yili; Barbic, Jernej

    2014-09-01

    The penalty method is a simple and popular approach to resolving contact in computer graphics and robotics. Penalty-based contact, however, suffers from stability problems due to the highly variable and unpredictable net stiffness, and this is particularly pronounced in simulations with time-varying distributed geometrically complex contact. We employ semi-implicit integration, exact analytical contact gradients, symbolic Gaussian elimination and a SVD solver to simulate stable penalty-based frictional contact with large, time-varying contact areas, involving many rigid objects and articulated rigid objects in complex conforming contact and self-contact. We also derive implicit proportional-derivative control forces for real-time control of articulated structures with loops. We present challenging contact scenarios such as screwing a hexbolt into a hole, bowls stacked in perfectly conforming configurations, and manipulating many objects using actively controlled articulated mechanisms in real time. PMID:26357376

  11. Localized contact formation by erythrocyte membranes: electrostatic effects.

    PubMed Central

    Thomas, N E; Coakley, W T

    1995-01-01

    The topology of the contact seam of human erythrocytes adhered by dextran, an uncharged polymer, has been examined. Particular attention has been paid to the influence of electrostatic intermembrane interactions since their magnitude and range can be accurately estimated. Normal cells formed a continuous seam, whereas erythrocytes with pronase-modified glycocalices formed localized contact points on adhesion in 72 kDa dextran in buffered 145 mM NaCl. The dependence of the inter-contact distance lambda on dextran concentration [D] over the range 2-6% w/v, was given by lambda = C[D]-0.62, where C was a constant. The index of [D] was independent of dextran molecular mass over the range 20 to 450 kDa. The inter-contact distance for pronase-pretreated cells in 6% w/v 72 kDa dextran increased from 0.78 to 1.4 microns as [NaCl] was reduced through the range 145 to 90 mM and the suspending phase was maintained at isotonicity by using sorbitol to replace NaCl. The formation and lateral separation of the contact points are discussed from the perspective of linear interfacial instability theory. The theory allows a quantitative explanation for the experimentally observed dependence of inter-contact distance and of disturbance growth rate on change in electrostatic interaction. The results suggest that the dominant wavelength, determining the inter-contact distance, is established on approaching membranes when the layers of cell surface charge are separated by a perpendicular distance of < 14 nm (bilayer separation of 24 nm). Images FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 PMID:8534809

  12. Expanded Human Blood-Derived γδT Cells Display Potent Antigen-Presentation Functions

    PubMed Central

    Khan, Mohd Wajid A.; Curbishley, Stuart M.; Chen, Hung-Chang; Thomas, Andrew D.; Pircher, Hanspeter; Mavilio, Domenico; Steven, Neil M.; Eberl, Matthias; Moser, Bernhard

    2014-01-01

    Cell-based immunotherapy strategies target tumors directly (via cytolytic effector cells) or aim at mobilizing endogenous anti-tumor immunity. The latter approach includes dendritic cells (DC) most frequently in the form of in vitro cultured peripheral blood monocytes-derived DC. Human blood γδT cells are selective for a single class of non-peptide agonists (“phosphoantigens”) and develop into potent antigen-presenting cells (APC), termed γδT-APC within 1–3 days of in vitro culture. Availability of large numbers of γδT-APC would be advantageous for use as a novel cellular vaccine. We here report optimal γδT cell expansion (>107 cells/ml blood) when peripheral blood mononuclear cells (PBMC) from healthy individuals and melanoma patients were stimulated with zoledronate and then cultured for 14 days in the presence of IL-2 and IL-15, yielding γδT cell cultures of variable purity (77 ± 21 and 56 ± 26%, respectively). They resembled effector memory αβT (TEM) cells and retained full functionality as assessed by in vitro tumor cell killing as well as secretion of pro-inflammatory cytokines (IFNγ, TNFα) and cell proliferation in response to stimulation with phosphoantigens. Importantly, day 14 γδT cells expressed numerous APC-related cell surface markers and, in agreement, displayed potent in vitro APC functions. Day 14 γδT cells from PBMC of patients with cancer were equally effective as their counterparts derived from blood of healthy individuals and triggered potent CD8+ αβT cell responses following processing and cross-presentation of simple (influenza M1) and complex (tuberculin purified protein derivative) protein antigens. Of note, and in clear contrast to peripheral blood γδT cells, the ability of day 14 γδT cells to trigger antigen-specific αβT cell responses did not depend on re-stimulation. We conclude that day 14 γδT cell cultures provide a convenient source of autologous APC for use in immunotherapy of patients with various cancers. PMID:25101086

  13. Direct-Write Contacts: Metallization and Contact Formation; Preprint

    SciTech Connect

    van Hest, M. F. A. M.; Curtis, C. J.; Miedaner, A.; Pasquarelli, R. M.; Kaydonova, T.; Hersh, P.; Ginley, D. S.

    2008-05-01

    Using direct-write approaches in photovoltaics for metallization and contact formation can significantly reduce the cost per watt of producing photovoltaic devices. Inks have been developed for various materials, such as Ag, Cu, Ni and Al, which can be used to inkjet print metallizations for various kinds of photovoltaic devices. Use of these inks results in metallization with resistivities close to those of bulk materials. By means of inkjet printing a metallization grid can be printed with better resolution, i.e. smaller lines, than screen-printing. Also inks have been developed to deposit transparent conductive oxide films by means of ultrasonic spraying.

  14. Vocalizations associated with pectoral fin contact in bottlenose dolphins (Tursiops truncatus).

    PubMed

    Evans-Wilent, J; Dudzinski, K M

    2013-11-01

    Pectoral fin contact in bottlenose dolphins represents one form of tactile communication. Acoustic communication associated with pectoral fin contact is an additional level of communication that may change or enhance the tactile message between two individuals. In this study, we examine vocalization types associated with pectoral fin contact in a group of captive bottlenose dolphins (Tursiops truncatus). From 2006 to 2009, vocalizations potentially associated with 748 pectoral fin contacts were examined: whistles, click trains and overlap of whistles and click trains were documented when associated with fin contact. Dolphins were also documented not vocalizing when exchanging pectoral fin contacts. Call type associated with pectoral fin contact was compared for the proportion of the type of pectoral fin contact, vocalizer sex, initiator and receiver roles, and gender pair. Overall, vocalizations differed significantly by vocalizer role as rubber or rubbee, initiator, and sex. Receivers and rubbees clicked and used overlap vocalizations more frequently, and males produced overlap vocalizations more frequently. These results suggest that whistles may be used to initiate pectoral fin contact or show preference for a particular partner, while click trains may be used to show disinterest in pectoral fin contact or to signal the end of a contact. Examining vocalizations produced in conjunction with tactile contact is a relatively new approach in the study of individual dolphin behavior and may be useful for understanding dolphin social alliances and social preferences for various individuals within a population. PMID:23954831

  15. Contact structure for use in catalytic distillation

    DOEpatents

    Jones, E.M. Jr.

    1984-03-27

    A method is described for conducting catalytic chemical reactions and fractionation of the reaction mixture comprising feeding reactants into a distillation column reactor, contracting said reactant in liquid phase with a fixed bed catalyst in the form of a contact catalyst structure consisting of closed porous containers containing the catalyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column. 7 figs.

  16. Contact structure for use in catalytic distillation

    DOEpatents

    Jones, Jr., Edward M.

    1985-01-01

    A method and apparatus for conducting catalytic chemical reactions and fractionation of the reaction mixture, comprising and feeding reactants into a distillation column reactor contracting said reactant in a liquid phase with a fixed bed catalyst in the form of a contact catalyst structure, consisting of closed porous containers containing the catalyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column.

  17. Contact structure for use in catalytic distillation

    DOEpatents

    Jones, Jr., Edward M.

    1984-01-01

    A method for conducting catalytic chemical reactions and fractionation of the reaction mixture comprising feeding reactants into a distillation column reactor contracting said reactant in liquid phase with a fixed bed catalyst in the form of a contact catalyst structure consisting of closed porous containers containing the catatlyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column.

  18. Contact structure for use in catalytic distillation

    DOEpatents

    Jones, E.M. Jr.

    1985-08-20

    A method and apparatus are disclosed for conducting catalytic chemical reactions and fractionation of the reaction mixture, comprising and feeding reactants into a distillation column reactor contracting said reactant in a liquid phase with a fixed bed catalyst in the form of a contact catalyst structure, consisting of closed porous containers containing the catalyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column. 7 figs.

  19. Contact Trees: Network Visualization beyond Nodes and Edges

    PubMed Central

    Sallaberry, Arnaud; Fu, Yang-chih; Ho, Hwai-Chung; Ma, Kwan-Liu

    2016-01-01

    Node-Link diagrams make it possible to take a quick glance at how nodes (or actors) in a network are connected by edges (or ties). A conventional network diagram of a “contact tree” maps out a root and branches that represent the structure of nodes and edges, often without further specifying leaves or fruits that would have grown from small branches. By furnishing such a network structure with leaves and fruits, we reveal details about “contacts” in our ContactTrees upon which ties and relationships are constructed. Our elegant design employs a bottom-up approach that resembles a recent attempt to understand subjective well-being by means of a series of emotions. Such a bottom-up approach to social-network studies decomposes each tie into a series of interactions or contacts, which can help deepen our understanding of the complexity embedded in a network structure. Unlike previous network visualizations, ContactTrees highlight how relationships form and change based upon interactions among actors, as well as how relationships and networks vary by contact attributes. Based on a botanical tree metaphor, the design is easy to construct and the resulting tree-like visualization can display many properties at both tie and contact levels, thus recapturing a key ingredient missing from conventional techniques of network visualization. We demonstrate ContactTrees using data sets consisting of up to three waves of 3-month contact diaries over the 2004-2012 period, and discuss how this design can be applied to other types of datasets. PMID:26784350

  20. Special killing forms on toric Sasaki-Einstein spaces

    NASA Astrophysics Data System (ADS)

    Visinescu, Mihai

    2014-11-01

    We summarize recent results on the construction of the special Killing forms on toric Sasaki-Einstein manifolds. The Killing forms are associated with the contact forms of the Sasaki spaces. Besides these there are two additional Killing forms connected with the parallel forms of the Calabi-Yau cone manifolds.

  1. Neuropeptide W exerts a potent suppressive effect on blood leptin and insulin concentrations in the rat.

    PubMed

    Rucinski, Marcin; Nowak, Krzysztof W; Chmielewska, Joanna; Ziolkowska, Agnieszka; Malendowicz, Ludwik K

    2007-03-01

    Neuropeptide B/W receptor 1 (NPBWR1) and neuropeptide B/W receptor 2 (NPBWR2) are two structurally related orphan receptors linked to protein G. In rodents NPBWR2 is absent, and its counterpart is described as being similar to neuropeptide B/W receptor 2. Endogenous ligands of these receptors have been identified. One of them is 29 amino acid residues long, uniquely modified with bromine and, thus, termed neuropeptide B (NPB). The other, neuropeptide W (NPW), has been identified in two molecular forms of 23 and 30 amino acids (NPW23 and NPW30), respectively. Both NPB and NPW affect food intake and energy expenditure. Since leptin, a potent anti-obesity hormone, and insulin are involved in the control of energy homeostasis, the present study aimed to investigate whether NPB and NPW affect leptin and insulin secretion in the rat. RT-PCR technique revealed the presence of ppNPB, ppNPW, NPBWR1 and NPBWR2-like mRNAs in isolated pancreatic islets of the rat. NPB and NPW immunoreactivities were observed in all of the cells of the pancreatic islets. Only when a higher dose was administered (3 nmol/100 g body weight) did NPW transiently lower blood insulin levels whereas NPB injection did not alter insulinaemia in the studied rats. At 30 min, but not 60, of the experiment, NPW notably lowered blood leptin concentrations at both tested doses. On the contrary, NPB injections had no effect on blood leptin and insulin concentrations. Thus, the results suggest that NPW but not NPB exerts a potent suppressive effect on blood leptin concentrations in the rat, and this mechanism may be involved in NPW regulation of energy homeostasis. PMID:17273787

  2. Highly optimized DNA vaccine targeting human telomerase reverse transcriptase stimulates potent antitumor immunity.

    PubMed

    Yan, Jian; Pankhong, Panyupa; Shin, Thomas H; Obeng-Adjei, Nyamekye; Morrow, Matthew P; Walters, Jewell N; Khan, Amir S; Sardesai, Niranjan Y; Weiner, David B

    2013-09-01

    High levels of human telomerase reverse transcriptase (hTERT) are detected in more than 85% of human cancers. Immunologic analysis supports that hTERT is a widely applicable target recognized by T cells and can be potentially studied as a broad cancer immunotherapeutic, or a unique line of defense against tumor recurrence. There remains an urgent need to develop more potent hTERT vaccines. Here, a synthetic highly optimized full-length hTERT DNA vaccine (phTERT) was designed and the induced immunity was examined in mice and non-human primates (NHP). When delivered by electroporation, phTERT elicited strong, broad hTERT-specific CD8 T-cell responses including induction of T cells expressing CD107a, IFN-?, and TNF-? in mice. The ability of phTERT to overcome tolerance was evaluated in an NHP model, whose TERT is 96% homologous to that of hTERT. Immunized monkeys exhibited robust [average 1,834 spot forming unit (SFU)/10(6) peripheral blood mononuclear cells (PBMC)], diverse (multiple immunodominant epitopes) IFN-? responses and antigen-specific perforin release (average 332 SFU/10(6) PBMCs), suggesting that phTERT breaks tolerance and induces potent cytotoxic responses in this human-relevant model. Moreover, in an HPV16-associated tumor model, vaccination of phTERT slows tumor growth and improves survival rate in both prophylactic and therapeutic studies. Finally, in vivo cytotoxicity assay confirmed that phTERT-induced CD8 T cells exhibited specific cytotoxic T lymphocyte (CTL) activity, capable of eliminating hTERT-pulsed target cells. These findings support that this synthetic electroporation-delivered DNA phTERT may have a role as a broad therapeutic cancer vaccine candidate. PMID:24777680

  3. Pseudosaccharin amines as potent and selective KV1.5 blockers.

    PubMed

    Lloyd, John; Finlay, Heather J; Kover, Alexander; Johnson, James; Pi, Zulan; Jiang, Ji; Neels, James; Cavallaro, Cullen; Wexler, Ruth; Conder, Mary Lee; Shi, Hong; Li, Danshi; Sun, Huabin; Chimalakonda, Anjaneya; Huang, Christine; Salvati, Mark; Levesque, Paul

    2015-11-01

    Phenethyl aminoheterocycles like compound 1 were known to be potent I(Kur) blockers although they lacked potency in vivo. Modification of the heterocycle led to the design and synthesis of pseudosaccharin amines. Compounds such as 14, 17d and 21c were found to be potent K(V)1.5 blockers and selective over other cardiac ion channels. These compounds had potent pharmacodynamic activity, however, they also showed off-target activities such as hemodynamic effects. PMID:25801931

  4. Low resistance contacts for shallow junction semiconductors

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S. (Inventor); Weizer, Victor G. (Inventor)

    1994-01-01

    A method of enhancing the specific contact resistivity in InP semiconductor devices and improved devices produced thereby are disclosed. Low resistivity values are obtained by using gold ohmic contacts that contain small amounts of gallium or indium and by depositing a thin gold phosphide interlayer between the surface of the InP device and the ohmic contact. When both the thin interlayer and the gold-gallium or gold-indium contact metallizations are used, ultra low specific contact resistivities are achieved. Thermal stability with good contact resistivity is achieved by depositing a layer of refractory metal over the gold phosphide interlayer.

  5. Study of Contact Resistances in Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Buehler, M. G.; Lambe, J.; Suszko, S. F.

    1985-01-01

    Techniques explored in search for rapid, reliable test. Resistances of aluminum/silicon contacts and methods to measure subjects of NASA report. Study with three tasks undertaken to evaluate nature and reliability of large numbers of semiconductor contacts of type now being fabricated in integrated circuits: Develop yield analysis for series strings of contacts using wafer-level electrical measurements, and identify different types of faults by visual inspection; develop wafer-level tests to evaluate reliability of contact strings; and develop mathematical model for current flow in contacts and examine contact region for evidence of micro-alloying.

  6. Contact Dermatitis, Patch Testing, and Allergen Avoidance.

    PubMed

    Burkemper, Nicole M

    2015-01-01

    In patients presenting with a complaint of rash, contact dermatitis is often the underlying diagnosis making it an entity with which health care providers should be familiar. Contact dermatitis can be divided into irritant contact dermatitis and allergic contact dermatitis. In a patient suspected of having allergic contact dermatitis, patch testing can be done to identify specific allergens. Education focused on allergen avoidance and safe products is an integral part of treatment for the contact dermatitis patient. Knowledge of the most common allergens is helpful for clinicians to be able to provide this education. PMID:26455061

  7. Method for manufacturing electrical contacts for a thin-film semiconductor device

    DOEpatents

    Carlson, David E.; Dickson, Charles R.; D'Aiello, Robert V.

    1988-11-08

    A method of fabricating spaced-apart back contacts on a thin film of semiconductor material by forming strips of buffer material on top of the semiconductor material in locations corresponding to the desired dividing lines between back contacts, forming a film of metal substantially covering the semiconductor material and buffer strips, and scribing portions of the metal film overlying the buffer strips with a laser without contacting the underlying semiconductor material to separate the metal layer into a plurality of back contacts. The buffer material serves to protect the underlying semiconductor material from being damaged during the laser scribing. Back contacts and multi-cell photovoltaic modules incorporating such back contacts also are disclosed.

  8. Non-hinge-binding pyrazolo[1,5-a]pyrimidines as potent B-Raf kinase inhibitors

    SciTech Connect

    Berger, Dan M.; Torres, Nancy; Dutia, Minu; Powell, Dennis; Ciszewski, Greg; Gopalsamy, Ariamala; Levin, Jeremy I.; Kim, Kyung-Hee; Xu, Weixin; Wilhelm, James; Hu, YongBo; Collins, Karen; Feldberg, Larry; Kim, Steven; Frommer, Eileen; Wojciechowicz, Donald; Mallon, Robert

    2010-11-19

    As part of our research effort to discover B-Raf kinase inhibitors, we prepared a series of C-3 substituted N-(3-(pyrazolo[1,5-a]pyrimidin-7-yl)phenyl)-3-(trifluoromethyl)benzamides. X-ray crystallography studies revealed that one of the more potent inhibitors (10n) bound to B-Raf kinase without forming a hinge-binding hydrogen bond. With basic amine residues appended to C-3 aryl residues, cellular activity and solubility were enhanced over previously described compounds of this class.

  9. 2-Sulfonamidopyridine C-region analogs of 2-(3-fluoro-4-methylsulfonamidophenyl)propanamides as potent TRPV1 antagonists.

    PubMed

    Ann, Jihyae; Ki, Yooran; Yoon, Suyoung; Kim, Myeong Seop; Lee, Jung-Un; Kim, Changhoon; Lee, Sunho; Jung, Aeran; Baek, Jisoo; Hong, Sunhye; Choi, Sun; Pearce, Larry V; Esch, Timothy E; Turcios, Noe A; Lewin, Nancy E; Ogunjirin, Adebowale E; Herold, Brienna K A; McCall, Anna K; Blumberg, Peter M; Lee, Jeewoo

    2016-03-15

    A series of 2-sulfonamidopyridine C-region derivatives of 2-(3-fluoro-4-methylsulfonamidophenyl)propanamide were investigated as hTRPV1 ligands. Systematic modification on the 2-sulfonamido group provided highly potent TRPV1 antagonists. The N-benzyl phenylsulfonamide derivatives 12 and 23 in particular showed higher affinities than that of lead compound 1. Compound 12 exhibited strong analgesic activity in the formalin pain model. Docking analysis of its chiral S-form 12S in our hTRPV1 homology model indicated that its high affinity might arise from additional hydrophobic interactions not present in lead compound 1S. PMID:26860926

  10. Dielectric fluctuations and the origins of non-contact friction

    PubMed Central

    Kuehn, Seppe; Loring, Roger F.; Marohn, John A.

    2006-01-01

    Dielectric fluctuations underlie a wide variety of physical phenomena, from ion mobility in electrolyte solutions and decoherence in quantum systems to dynamics in glass-forming materials and conformational changes in proteins. Here we show that dielectric fluctuations also lead to non-contact friction. Using high sensitivity, custom fabricated, single crystal silicon cantilevers we measure energy losses over poly(methyl methacrylate), poly(vinyl acetate), and polystyrene thin films. A new theoretical analysis, relating non-contact friction to the dielectric response of the film, is consistent with our experimental observations. This work constitutes the first direct, mechanical detection of friction due to dielectric fluctuations. PMID:16712172

  11. The Importance of Immediate Postnatal Contact: Its Effect on Breastfeeding

    PubMed Central

    Thomson, Mary Ellen; Hartsock, Thomas G.; Larson, Charles

    1979-01-01

    Breastfeeding is said to be the ideal form of infant nutrition, but promoting it is thought to be difficult. The results of this study show that success is more likely when breastfeeding and skin-to-skin contact begin in the delivery room. The procedure is simple and the contact period need to be of only 15-20 minutes duration. The primiparas in this study seemed contented, happy or excited with the experience. Possibly it is most beneficial to those mothers who have not asked to hold their infants at birth. PMID:21297814

  12. A contact layer element for large deformations

    NASA Astrophysics Data System (ADS)

    Weißenfels, C.; Wriggers, P.

    2015-05-01

    In many contact situations the material behavior of one contact member strongly influences the force acting between the two bodies. Unfortunately standard friction models cannot reproduce all of these material effects at the contact layer and often continuum interface elements are used instead. These elements are intrinsically tied to the fixed grid and hence cannot be used in large sliding simulations. Due to the shortcomings of the standard contact formulations and of the interface elements a new type of a contact layer element is developed in this work. The advantages of this element are the direct implementation of continuum models into the contact formulation and the application to arbitrary large deformations. Showing a relation between continuum and contact kinematics based on the solid-shell concept the new contact element is at the end a natural extension of the standard contact formulations into 3D. Two examples show that the continuum behavior can be exactly reproduced at the contact surface even in large sliding situations using this contact layer element. For the discretization of the new contact element the Mortar method is chosen exemplary, but it can be combined with all kinds of contact formulations.

  13. Towards an optimal contact metal for CNTFETs.

    PubMed

    Fediai, Artem; Ryndyk, Dmitry A; Seifert, Gotthard; Mothes, Sven; Claus, Martin; Schröter, Michael; Cuniberti, Gianaurelio

    2016-05-21

    Downscaling of the contact length Lc of a side-contacted carbon nanotube field-effect transistor (CNTFET) is challenging because of the rapidly increasing contact resistance as Lc falls below 20-50 nm. If in agreement with existing experimental results, theoretical work might answer the question, which metals yield the lowest CNT-metal contact resistance and what physical mechanisms govern the geometry dependence of the contact resistance. However, at the scale of 10 nm, parameter-free models of electron transport become computationally prohibitively expensive. In our work we used a dedicated combination of the Green function formalism and density functional theory to perform an overall ab initio simulation of extended CNT-metal contacts of an arbitrary length (including infinite), a previously not achievable level of simulations. We provide a systematic and comprehensive discussion of metal-CNT contact properties as a function of the metal type and the contact length. We have found and been able to explain very uncommon relations between chemical, physical and electrical properties observed in CNT-metal contacts. The calculated electrical characteristics are in reasonable quantitative agreement and exhibit similar trends as the latest experimental data in terms of: (i) contact resistance for Lc = ∞, (ii) scaling of contact resistance Rc(Lc); (iii) metal-defined polarity of a CNTFET. Our results can guide technology development and contact material selection for downscaling the length of side-contacts below 10 nm. PMID:27124382

  14. Comparing the relative benefits of grooming-contact and full-contact pairing for laboratory-housed adult female Macaca fascicularis

    PubMed Central

    Lee, Grace H.; Thom, Jinhee P.; Chu, Katherine L.; Crockett, Carolyn M.

    2011-01-01

    Tactile social contact is the most effective form of environmental enrichment for promoting normal behavior in captive primates. For laboratory macaques housed indoors, pair housing is the most common method for socialization. Pairs can be housed either in full contact (FC), or in protected contact (PC). At Washington National Primate Research Center, PC is provided by grooming-contact (GC) cages whereby two partners are housed individually in adjacent cages with access to each other through widely spaced vertical bars. Grooming-contact has been used to accommodate research protocol restrictions and improve the likelihood of compatibility for various pairings, in part by enabling male-female pairs. This study compares the benefits between the two housing types by video recording 14 pairs of adult female Macaca fascicularis in four sequential housing phases following an ABBA design: baseline grooming-contact, full contact shortly after introduction, 1-month-later full contact, and after reversion to grooming-contact. Prior to this study, pairs had been housed compatibly in GC. Twelve of the 14 long-term pairs transitioned successfully to full contact and data presented exclude the two failed pairs. Allogrooming increased significantly when pairs first switched from GC to FC (P = 0.018), but the effect did not last through the on 1-month-later FC phase suggesting that the initial improvement in affiliative behavior was a transitory novelty response that did not persist. Self-grooming significantly decreased between the first GC and first FC phases (P = 0.016), likely due to redirected allogrooming. Non-contact affiliative behavior towards partner or other conspecifics in the room did not differ, nor did agonism towards partner or others in the room. Occurrence of abnormal, tension, manipulation, miscellaneous active, and inactive behaviors did not differ significantly across housing phases. Proximity measurements indicated that pairs were significantly out of arm’s reach more often in protected contact than when in full contact (P ≤ 0.02). Proportion of time spent in physical contact significantly increased between the first GC and first FC phases (P = 0.002), but subsequently declined. For both FC phases, partners chose to spend about 50% of their time in the same cage. Few behavioral improvements were seen after pairs switched to full contact and no negative effects came of reversion to grooming contact. This study suggests that tactile contact provided through widely spaced bars (grooming-contact) is a viable alternative to full contact housing for adult female longtailed macaques. It provides a degree of social housing while allowing both partners choice and control, key concepts in contemporary animal welfare guidelines. PMID:22685366

  15. Humidity-induced room-temperature decomposition of Au contacted indium phosphide

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Weizer, Victor G.

    1990-01-01

    It has been found that Au-contacted InP is chemically unstable at room temperature in a humid ambient due to the leaching action of indium nitrate islands that continually remove In from the contact metallization and thus, in effect, from the Inp substrate. While similar appearing islands form on Au-contacted GaAs, that system appears to be stable since leaching of the group III element does not take place.

  16. Investigating How Contact Angle Effects the Interaction between Water and a Hydrophobic Surface

    NASA Astrophysics Data System (ADS)

    Poynor, Adele; Neidig, Caitlyn

    2012-02-01

    By definition hydrophobic substances hate water. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low-density region forms near the surface. Contact angle is a measure of how hydrophobic a surface is. We have employed an automated home-built Surface Plasmon Resonance (SPR) apparatus to investigate the effect of varying the contact angle on the depletion layer

  17. Thermal Conductances Of Metal Contacts

    NASA Technical Reports Server (NTRS)

    Salerno, L. J.; Kittel, P.; Scherkenbach, F. E.; Spivak, A. L.

    1988-01-01

    Report presents results of measurements of thermal conductances of aluminum and stainless-steel contacts at temperatures from 1.6 to 6.0 K. Measurement apparatus includes gearmotor assembly connected to rocker arm by music wire to load sample pair with forces up to 670 N. Heater placed above upper sample. Germanium resistance thermometers in upper and lower samples measured temperature difference across interface over range of heater powers from 0.1 to 10.0 mW. The thermal conductance calculated from temperature difference. Measurements provide data for prediction of thermal conductances of bolted joints in cryogenic infrared instruments.

  18. Seeking Contact: Issues to Consider

    NASA Astrophysics Data System (ADS)

    Michaud, M.

    Seeking contact with extraterrestrial intelligence is a species enterprise that should be conducted with our shared interests in mind. We must reflect on the full range of possible outcomes; we cannot opt out of the potential consequences of actions taken by small numbers of our fellow humans. Until we have empirical evidence about alien technological civilizations, we can reason about them only by analogy with our own history and behaviour. Given that record, some degree of prudence is in order. To conduct this debate more rationally, we must free our thinking of excessively binary stereotypes.

  19. Smart contact oscillations by IPMCs

    NASA Astrophysics Data System (ADS)

    Asanuma, H.; Asaka, K.; Su, J.; Poubel, L.; Shahinpoor, M.

    2016-02-01

    An ion migration-induced self-oscillation phenomenon observed in ionic polymer metal composites (IPMCs) is reported. These oscillations are generated from a purely static equilibrium configuration of IPMCs in loose contact with a stationary electrode, and in particular the anode of an imposed DC voltage source. Many interesting possibilities emerge, which are described in this paper. Of particular importance is the emergence of the possibility of creating tailor-made electric signals or pulse-width modulation-type signals from a DC source.

  20. Contact dermatitis: facts and controversies.

    PubMed

    Wolf, Ronni; Orion, Edith; Ruocco, Eleonora; Baroni, Adone; Ruocco, Vincenzo

    2013-01-01

    The history of contact dermatitis (CD) is inseparable from the history of the patch test, and the patch test is inseparable from the pioneer in the field, Josef Jadassohn (1860-1936). Despite the fact that we have been diagnosing, treating, and investigating the condition for more than 100 years, there are still many unsolved questions and controversies, which show no signs of coming to an end in the foreseeable future. This contribution reviews and highlights some of the disagreements and discrepancies associated with CD. For example: • What is the real sensitizer in balsam of Peru, one of the most common allergens, and what, if any, is the value of a low-balsam diet? • Is benzalkonium chloride, which has well-known and undisputed irritant properties, a contact allergen as well? • Is cocamidopropyl betaine (CABP) a common contact allergen and what is the actual sensitizer in CABP allergy the molecule itself, or impurities, or intermediaries in its synthesis? • How can the significant differences in the prevalence of sensitization of formaldehyde (FA, a common cause of contact allergy) between the United States (8%-9%) and Europe (2%-3%) be explained? • What is the relationship between formaldehyde releasers (FRs) allergy and an FA allergy? Should we recommend that FA-allergic patients also avoid FRs, and, if so, to what extent? • What is the true frequency of lanolin allergy? This issue remains enigmatic despite the expenditure of thousands of dollars and the innumerable hours spent investigating this subject. • What is the basis behind the so-called "lanolin paradox"? This label was coined in 1996 and is still a matter of controversy. • Is there such a thing as systemic CD from nickel, and, if so, to what extent? Is there a cross-reactivity or concomitant sensitization between nickel and cobalt?These are some of the controversial problems discussed. We have selected the ones that we consider to be of special interest and importance to the practicing dermatologist. PMID:23806164