WorldWideScience

Sample records for exhibiting m-m bonding

  1. An Extended Chain and Trinuclear Complexes Based on Pt(II)-M (M = Tl(I), Pb(II)) Bonds: Contrasting Photophysical Behavior.

    Science.gov (United States)

    Forniés, Juan; Giménez, Nora; Ibáñez, Susana; Lalinde, Elena; Martín, Antonio; Moreno, M Teresa

    2015-05-04

    The syntheses and structural characterizations of a Pt-Tl chain [{Pt(bzq)(C6F5)2}Tl(Me2CO)]n 1 and two trinuclear Pt2M clusters (NBu4)[{Pt(bzq)(C6F5)2}2Tl] 2 and [{Pt(bzq)(C6F5)2}2Pb] 3 (bzq = 7,8-benzoquinolinyl), stabilized by donor-acceptor Pt → M bonds, are reported. The one-dimensional heterometallic chain 1 is formed by alternate "Pt(bzq)(C6F5)2" and "Tl(Me2CO)" fragments, with Pt-Tl bond separations in the range of 2.961(1)-3.067(1) Å. The isoelectronic trinuclear complexes 2 (which crystallizes in three forms, namely, 2a, 2b, and 2c) and 3 present a sandwich structure in which the Tl(I) or Pb(II) is located between two "Pt(bzq)(C6F5)2" subunits. NMR studies suggest equilibria in solution implying cleavage and reformation of Pt-M bonds. The lowest-lying absorption band in the UV-vis spectra in CH2Cl2 and tetrahydrofuran (THF) of 1, associated with (1)MLCT/(1)L'LCT (1)[5dπ(Pt) → π*(bzq)]/(1)[(C6F5) → bzq], displays a blue shift in relation to the precursor, suggesting the cleavage of the chain maintaining bimetallic Pt-Tl fragments in solution, also supported by NMR spectroscopy. In 2 and 3, it shows a blue shift in THF and a red shift in CH2Cl2, supporting a more extensive cleavage of the Pt-M bonds in THF solutions than in CH2Cl2, where the trinuclear entities are predominant. The Pt-Tl chain 1 displays in solid state a bright orange-red emission ascribed to (3)MM'CT (M' = Tl). It exhibits remarkable and fast reversible vapochromic and vapoluminescent response to donor vapors (THF and Et2O), related to the coordination/decoordination of the guest molecule to the Tl(I) ion, and mechanochromic behavior, associated with the shortening of the intermetallic Pt-Tl separations in the chain induced by grinding. In frozen solutions (THF, acetone, and CH2Cl2) 1 shows interesting luminescence thermochromism with emissions strongly dependent on the solvent, concentration, and excitation wavelengths. The Pt2Tl complex 2 shows an emission close to 1, ascribed to

  2. 7 CFR Exhibit F to Subpart A of... - Payment Bond

    Science.gov (United States)

    2010-01-01

    ... REGULATIONS CONSTRUCTION AND REPAIR Planning and Performing Construction and Other Development Pt. 1924, Subpt...) Surety ATTEST: Witness as to Surety (Address) By Attorney-in-Fact (Address) Note. Date of BOND must not...

  3. Micro push-out bond strength of resin cement in roots exhibiting the butterfly effect.

    Science.gov (United States)

    Arslan, Hakan; Uygun, Ahmet Demirhan; Gündüz, Hicran Ateş; Karataş, Ertugrul; Cakici, Fatih; Alsancak, Meltem

    2015-01-01

    The aim of this study was to determine the bond strength of resin cement in root sections with or without butterfly effect. Fifteen single-rooted human maxillary central incisors were decoronated and prepared up to size 40. After post space preparation, the resin cement was placed into the post space and the fiber posts were luted. 1 mm thickness slices were obtained and the presence of the butterfly effect was recorded. A push-out test was then used to measure the bond strength between the resin cement and root dentin. Data were analyzed using independent samples of t and χ(2) tests (p = 0.05). The sections exhibiting butterfly effect showed higher push-out bond strength values than those of without butterfly effect (p Butterfly effect can influence the push-out bond strength. Thus, this phenomena should be taken into account, when push-out bond strength test is performed. Root sections exhibiting butterfly effect resulted in higher push-out bond strength values to root sections without butterfly effect. © Wiley Periodicals, Inc.

  4. Exhibition of veiled features in diffusion bonding of titanium alloy and stainless steel via copper

    Science.gov (United States)

    Thirunavukarasu, Gopinath; Kundu, Sukumar; Laha, Tapas; Roy, Deb; Chatterjee, Subrata

    2017-11-01

    An investigation was carried out to know the extent of influence of bonding-time on the interface structure and mechanical properties of diffusion bonding (DB) of TiA|Cu|SS. DB of Ti6Al4V (TiA) and 304 stainless steel (SS) using pure copper (Cu) of 200-μm thickness were processed in vacuum using 4-MPa bonding-pressure at 1123 K from 15 to 120 min in steps of 15 min. Preparation of DB was not possible when bonding-time was less than 60 min as the bonding at Cu|SS interface was unsuccessful in spite of effective bonding at TiA|Cu interface; however, successful DB were produced when the bonding-time was 60 min and beyond. DB processed for 60 and 75 min (classified as shorter bonding-time interval) showed distinctive characteristics (structural, mechanical, and fractural) as compared to the DB processed for 90, 105, and 120 min (classified as longer bonding-time interval). DB processed for 60 and 75 min exhibited layer-wise Cu–Ti-based intermetallics at TiA|Cu interface, whereas Cu|SS interface was completely free from reaction products. The layer-wise structure of Cu–Ti-based intermetallics were not observed at TiA|Cu interface in the DB processed for longer bonding-time; however, the Cu|SS interface had layer-wise ternary intermetallic compounds (T1, T2, and T3) of Cu–Fe–Ti-based along with σ phase depending upon the bonding-time chosen. Diffusivity of Ti-atoms in Cu-layer (DTi in Cu-layer) was much greater than the diffusivity of Fe-atoms in Cu-layer (DFe in Cu-layer). Ti-atoms reached Cu|SS interface but Fe-atoms were unable to reach TiA|Cu interface. It was observed that DB fractured at Cu|SS interface when processed for shorter bonding-time interval, whereas the DB processed for longer bonding-time interval fractured apparently at the middle of Cu-foil region predominantly due to the existence of brittle Cu–Fe–Ti-based intermetallics.

  5. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    A Look of Hope Islam Mahmoud Sweity From 19 to 30 June 2017 CERN Meyrin, Main Building Islam Mahmoud Sweity Islam Mahmoud Sweity was born in 1997 at Beit Awwa, Palestine. She is currently following a course to get an Art diploma of Painting at the college of Fine Arts at An-Najah National University under the supervision of Esmat Al As'aad. Her portraits, landscapes and still life paintings are full of life and shining colours. Charged of emotional empathy they catch the attention of the viewer and are reminding us that life is beautiful and worth living in spite of all difficulties we have to go through. She participated in many exhibitions and has exposed her drawings in 2015 at CERN and in France in the framework of the exhibition "The Origin“, and in 2017 in the Former Yugoslav Republic of Macedonia, Palestina and Jordan. In this exhibition the oil paintings made in the past year will be presented. For more information : staff.association@cern.ch | T&eacu...

  6. Exhibition

    CERN Multimedia

    Staff Association

    2016-01-01

    Encounters Hanne Blitz From February 1st to 12th 2016 CERN Meyrin, Main Building What is our reaction to a first encounter with a tourist attraction? Contemporary Dutch painter Hanne Blitz captures visitors' responses to art and architecture, sweeping vistas and symbolic memorials. Encounters, a series of oil paintings curated specially for this CERN exhibition, depicts tourists visiting cultural highlights around the world. A thought-provoking journey not to be missed, and a tip of the hat to CERN's large Hadron Collider.

  7. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Sintropie Flavio Pellegrini From 13 to 24 March 2017 CERN Meyrin, Main Building Energia imprigionata - Flavio Pellegrini. The exhibition is composed by eleven wood artworks with the expression of movement as theme. The artworks are the result of harmonics math applied to sculpture. The powerful black colour is dominated by the light source, generating reflexes and modulations. The result is a continuous variation of perspective visions. The works generate, at a first approach, an emotion of mystery and incomprehension, only a deeper contemplation lets one discover entangling and mutative details, evidencing the elegance of the lines and letting the meaning emerge. For more information : staff.association@cern.ch | Tél: 022 766 37 38

  8. Markov Model M/M/m/K in Contact Center

    Directory of Open Access Journals (Sweden)

    Erik Chromy

    2012-01-01

    Full Text Available Our paper deals with a contact center dimensioning. The main task of a contact center is to offer services to customers. The most simple and genuine way of communication with the contact center agent is by phone. From the customer satisfaction point of view, the shortest serving time is the most important factor. It is known that the highest operating costs of the contact center are costs for agents. Therefore, we need to choose the right number of agents and effectively utilize them. For contact center dimensioning we can use various models. In this paper, we introduce the Markov M/M/m/K model which offers the broad range of parameters suitable for the contact center sizing, e.g. required number of agents based on the probability of call refusal and probability of call enqueue.

  9. Disulfide Bond Oxidoreductase DsbA2 of Legionella pneumophila Exhibits Protein Disulfide Isomerase Activity

    OpenAIRE

    Kpadeh, Zegbeh Z.; Jameson-Lee, Max; Anthony J. Yeh; Chertihin, Olga; Shumilin, Igor A.; Dey, Rafik; Day, Shandra R.; Hoffman, Paul S.

    2013-01-01

    The extracytoplasmic assembly of the Dot/Icm type IVb secretion system (T4SS) of Legionella pneumophila is dependent on correct disulfide bond (DSB) formation catalyzed by a novel and essential disulfide bond oxidoreductase DsbA2 and not by DsbA1, a second nonessential DSB oxidoreductase. DsbA2, which is widely distributed in the microbial world, is phylogenetically distinct from the canonical DsbA oxidase and the DsbC protein disulfide isomerase (PDI)/reductase of Escherichia coli. Here we s...

  10. Gold nanoparticles physicochemically bonded onto tungsten disulfide nanosheet edges exhibit augmented plasmon damping

    Directory of Open Access Journals (Sweden)

    Gregory T. Forcherio

    2017-07-01

    Full Text Available Augmented plasmonic damping of dipole-resonant gold (Au nanoparticles (NP physicochemically bonded onto edges of tungsten disulfide (WS2 nanosheets, ostensibly due to hot electron injection, is quantified using electron energy loss spectroscopy (EELS. EELS allows single-particle spatial resolution. A measured 0.23 eV bandwidth expansion of the localized surface plasmon resonance upon covalent bonding of 20 nm AuNP to WS2 edges was deemed significant by Welch’s t-test. Approximately 0.19 eV of the measured 0.23 eV expansion went beyond conventional radiative and nonradiative damping mechanisms according to discrete dipole models, ostensibly indicating emergence of hot electron transport from AuNP into the WS2. A quantum efficiency of up to 11±5% spanning a 7 fs transfer process across the optimized AuNP-TMD ohmic junction is conservatively calculated. Putative hot electron transport for AuNP physicochemically bonded to TMD edges exceeded that for AuNP physically deposited onto the TMD basal plane. This arose from contributions due to (i direct physicochemical bond between AuNP and WS2; (ii AuNP deposition at TMD edge sites; and (iii lower intrinsic Schottky barrier. This improves understanding of photo-induced doping of TMD by metal NP which could benefit emerging catalytic and optoelectronic applications.

  11. Solution and solid-state properties of luminescent M-M bond-containing coordination/organometallic polymers using the RNC-M2(dppm)2-CNR building blocks (M = Pd, Pt; R = Aryl, Alkyl).

    Science.gov (United States)

    Bérubé, Jean-François; Gagnon, Karl; Fortin, Daniel; Decken, Andreas; Harvey, Pierre D

    2006-04-03

    Two families of organometallic polymers built upon the bimetallic M2(dppm)2L(2)2+ fragments (M = Pd, Pt; dppm = bis(diphenylphosphino)methane, L = 1,4-diisocyano-2,3,5,6-tetramethylbenzene (diiso), 1,8-diisocyano-p-menthane (dmb), 1-isocyano-2,6-dimethylbenzene, 1-isocyano-4-isopropylbenzene, and tert-butylisocyanide) were synthesized and fully characterized (1H and 31P NMR, X-ray crystallography (model compounds), IR, Raman, chem. anal., TGA, DSC, powder XRD, 31P NMR T1 and NOE, light scattering, and conductivity measurements). Evidence for polymers in the solid state is provided from the swelling of the polymers upon dissolution and the formation of stand-alone films. However, these species become small oligomers when dissolved. The materials are luminescent in the solid state at 298 and 77 K and in PrCN solution at 77 K. These emissions result from triplet 3(d sigma d sigma*) states despite the presence of low-lying pi-pi* MO levels according to DFT calculations for the aryl isocyanide model compounds. The emission band maxima are located between 640 and 750 nm and exhibit lifetimes of 3-6 ns for the Pd species and 3-4 micros for the Pt analogues in PrCN solution at 77 K. No evidence of intramolecular excitonic photoprocesses was found in any of the polymers.

  12. New Redox Polymers that Exhibit Reversible Cleavage of Sulfur Bonds as Cathode Materials.

    Science.gov (United States)

    Baloch, Marya; Ben Youcef, Hicham; Li, Chunmei; Garcia-Calvo, Oihane; Rodriguez, Lide M; Shanmukaraj, Devaraj; Rojo, Teofilo; Armand, Michel

    2016-11-23

    Two new cathode materials based on redox organosulfur polymers were synthesized and investigated for rechargeable lithium batteries as a proof-of-concept study. These cathodes offered good cycling performance owing to the absence of polysulfide solubility, which plagues Li/S systems. Herein, an aliphatic polyamine or a conjugated polyazomethine was used as the base to tether the redox-active species. The activity comes from the cleavage and formation of S-S or N-S bonds, which is made possible by the rigid conjugated backbone. The synthesized polymers were characterized through FTIR spectroscopy and thermogravimetric analysis (TGA). Galvanostatic measurements were performed to evaluate the discharge/charge cycles and characterize the performance of the lithium-based cells, which displayed initial discharge capacities of approximately 300 mA h g(-1) at C/5 over 100 cycles with approximately 98 % Coulombic efficiency. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. An intravenous clarithromycin lipid emulsion with a high drug loading, H-bonding and a hydrogen-bonded ion pair complex exhibiting excellent antibacterial activity

    Directory of Open Access Journals (Sweden)

    Haoyu Gong

    2016-10-01

    Full Text Available The aim of this study was to develop an intravenous clarithromycin lipid emulsion (CLE with good stability and excellent antibacterial activity. The CLE was prepared by the thin-film dispersed homogenization method. The interaction between clarithromycin (CLA and cholesteryl hemisuccinate (CHEMS was confirmed by DSC, FT-IR and 1H NMR analysis. The interfacial drug loading, thermal sterilization, freeze–thaw stability, and in vitro and in vivo antibacterial activity were investigated systematically. DSC, FT-IR and 1H NMR spectra showed that CHEMS (CLA: CHEMS, M ratio 1:2 could interact with CLA through H-bonding and a hydrogen-bonded ion pair. The CHEMS was found necessary to maintain the stability of CLE. Ultracentrifugation showed that almost 88% CLA could be loaded into the interfacial layer. The optimized CLE formulation could withstand autoclaving at 121 °C for 10 min and remain stable after three freeze–thaw cycles. The in vitro susceptibility test revealed that the CLA–CHEMS ion-pair and CLE have similar activity to the parent drug against many different bacterial strains. The in vivo antibacterial activity showed that the ED50 of intravenous CLE was markedly lower than that of CLA solution administrated orally. CLE exhibited pronounced antibacterial activity and might be a candidate for a new nanocarrier for CLA with potential advantages over the current commercial formulation.

  14. Security architecture of the M&M mobile agent framework

    Science.gov (United States)

    Marques, Paulo J.; Santos, Nuno F.; Silva, Luis; Silva, Joao G.

    2001-07-01

    In the Mobile Agent programming model, small threads of execution migrate from machine to machine, performing their operations locally. For being able to deploy such a model into real world applications, security is a vital concern. In the M&M project we have developed a system that departures from the traditional platform-based execution model for mobile agents. In M&M there are no agent platforms. Instead there is a component framework that allows the applications to become able of sending and receiving agents by themselves in a straightforward manner. In this paper we examine the security mechanisms available in M&M, and how integration with existing applications is done. One difficult aspect of this work is that all the features must work with the security mechanisms that already exist on the applications. This is so because the components are integrated from within into the applications, which already have security mechanisms in place. Currently, M&M provides features like fine-grain security permissions, encryption of agents and data, certificate distribution using LDAP and cryptographic primitives for agents. For validating the approach and solutions found, we have integrated the framework into several off-the-shelf web servers, having the security mechanisms running, with no problems.

  15. R M JOSHl-and M M PATEL* .

    Indian Academy of Sciences (India)

    7-Chelation ion-exchangc properties of salicylic acidQurea—formsldchyde copolymers - , . "' r '. R M JOSHl-and M M PATEL* . likgartmcnt of Chemistry, Sardar Patel University, Vallahhmdyansgar 388120, n 1a '. MS received 2 January 1982'; revised 5 June 1982. Abstract. Chclation ion-exchange properties of copolymers ...

  16. Glycerol-bonded 3C-SiC nanocrystal solid films exhibiting broad and stable violet to blue-green emission.

    Science.gov (United States)

    Wang, J; Xiong, S J; Wu, X L; Li, T H; Chu, Paul K

    2010-04-14

    We have produced glycerol-bonded 3C-SiC nanocrystal (NC) films, which when excited by photons of different wavelengths, produce strong and tunable violet to blue-green (360-540 nm) emission as a result of the quantum confinement effects rendered by the 3C-SiC NCs. The emission is so intense that the emission spots are visible to the naked eyes. The light emission is very stable and even after storing in air for more than six months, no intensity degradation can be observed. X-ray photoelectron spectroscopy and absorption fine structure measurements indicate that the Si-terminated NC surfaces are completely bonded to glycerol molecules. Calculations of geometry optimization and electron structures based on the density functional theory for 3C-SiC NCs with attached glycerol molecules show that these molecules are bonded on the NCs causing strong surface structural change, while the isolated levels in the conduction band of the bare 3C-SiC NCs are replaced with quasi-continuous bands that provide continuous tunability of the emitted light by changing the frequencies of exciting laser. As an application, we demonstrate the potential of using 3C-SiC NCs to fabricate full-color emitting solid films by incorporating porous silicon.

  17. Immersive Exhibitions

    DEFF Research Database (Denmark)

    Achiam, Marianne

    2015-01-01

    The immersive exhibition is a specialized exhibition genre in museums, which creates the illusion of time and place by representing key characteristics of a reference world and by integrating the visitor in this three-dimensionally reconstructed world (Mortensen 2010). A successful representation...... of the reference world depends on three criteria: whether the exhibition is staged as a coherent whole with all the displayed objects supporting the representation, whether the visitor is integrated as a component of the exhibition, and whether the content and message of the exhibition become dramatized...... as a result of the visitor’s interaction with the exhibit....

  18. Human Exhibitions

    DEFF Research Database (Denmark)

    Andreassen, Rikke

    From 1870s to 1910s, more than 50 exhibitions of so-called exotic people took place in Denmark. Here large numbers of people of Asian and African origin were exhibited for the entertainment and ‘education’ of a mass audience. Several of these exhibitions took place in Copenhagen Zoo. Here differe...

  19. Exhibit Engineering

    DEFF Research Database (Denmark)

    Mortensen, Marianne Foss

    ) a synthesis of the findings from the first two studies with findings from the literature to generate two types of results: a coherent series of suggestions for a design iteration of the studied exhibit as well as a more general normative model for exhibit engineering. Finally, another perspective...

  20. Exhibiting design

    DEFF Research Database (Denmark)

    Christensen, Line Hjorth

    2017-01-01

    This article explores how co-curatorial strategies and partnerships can work as driving forces for representing design, and how they can vitalize the exhibition as a media between enlightenment and experience. Focusing on Design Museum DK, drawing on historical as well as recent cases, it identif......This article explores how co-curatorial strategies and partnerships can work as driving forces for representing design, and how they can vitalize the exhibition as a media between enlightenment and experience. Focusing on Design Museum DK, drawing on historical as well as recent cases...

  1. Museum Exhibit

    Science.gov (United States)

    1991-01-01

    A TSP from NASA Tech Briefs provided the solution to an electrical problem at a Florida museum. When a model train would not start without a jerk, a Marshall Space Flight Center development called pulse width control was adapted. The new circuit enables the train to start smoothly and reduces construction and maintenance costs. The same technology is also used in another hands-on exhibit. Applications of other TSPs are anticipated.

  2. Human Exhibitions

    DEFF Research Database (Denmark)

    Andreassen, Rikke

    of displayed people, connecting the attitudes and science of the past with both our (continued) modern fascination with ‘the exotic’, and contemporary language and popular culture. As such, it will be of interest to scholars of sociology, anthropology and history working in the areas of gender and sexuality...... light on the staging of exhibitions, the daily life of the exhibitees, the wider connections between shows across Europe and the thinking of the time on matters of race, science, gender and sexuality. A window onto contemporary racial understandings, the book presents interviews with the descendants...

  3. Human Exhibitions

    DEFF Research Database (Denmark)

    Andreassen, Rikke

    , this book draws on unique archival material, including photographs, documentary evidence and newspaper articles, newly discovered in Copenhagen. This opens for new insights and perspectives on these European exhibitions. The book employs post-colonial and feminist approaches to the material to shed fresh...... of displayed people, connecting the attitudes and science of the past with both our (continued) modern fascination with ‘the exotic’, and contemporary language and popular culture. As such, it will be of interest to scholars of sociology, anthropology and history working in the areas of gender and sexuality...

  4. Signature of tilted Dirac cones in Weiss oscillations of 8 -P m m n borophene

    Science.gov (United States)

    Islam, SK Firoz; Jayannavar, A. M.

    2017-12-01

    Polymorph of 8 -P m m n borophene exhibits anisotropic tilted Dirac cones. In this work, we explore the consequences of the tilted Dirac cones in magnetotransport properties of a periodically modulated borophene. We evaluate modulation-induced diffusive conductivity by using linear response theory in low temperature regime. The application of weak spatial modulation (electric, magnetic or both) gives rise to the magnetic-field-dependent nonzero oscillatory drift velocity which causes Weiss oscillation in the longitudinal conductivity at low magnetic field. The Weiss oscillation is studied in the presence of a weak spatial electric, magnetic, and both modulations individually. The tilting of the Dirac cones gives rise to an additional contribution to the Weiss oscillation in longitudinal conductivity. Moreover, it also enhances the frequency of the Weiss oscillation and modifies its amplitude too. Most remarkably, it is found that the presence of both out-of-phase electric and magnetic modulations can cause a sizable valley polarization in diffusive conductivity. The origin of valley polarization lies in the opposite tilting of the two Dirac cones at two valleys.

  5. A candidate subspecies discrimination system involving a vomeronasal receptor gene with different alleles fixed in M. m. domesticus and M. m. musculus.

    Directory of Open Access Journals (Sweden)

    Robert C Karn

    2010-09-01

    Full Text Available Assortative mating, a potentially efficient prezygotic reproductive barrier, may prevent loss of genetic potential by avoiding the production of unfit hybrids (i.e., because of hybrid infertility or hybrid breakdown that occur at regions of secondary contact between incipient species. In the case of the mouse hybrid zone, where two subspecies of Mus musculus (M. m. domesticus and M. m. musculus meet and exchange genes to a limited extent, assortative mating requires a means of subspecies recognition. We based the work reported here on the hypothesis that, if there is a pheromone sufficiently diverged between M. m. domesticus and M. m. musculus to mediate subspecies recognition, then that process must also require a specific receptor(s, also sufficiently diverged between the subspecies, to receive the signal and elicit an assortative mating response. We studied the mouse V1R genes, which encode a large family of receptors in the vomeronasal organ (VNO, by screening Perlegen SNP data and identified one, Vmn1r67, with 24 fixed SNP differences most of which (15/24 are nonsynonymous nucleotide substitutions between M. m. domesticus and M. m. musculus. We observed substantial linkage disequilibrium (LD between Vmn1r67 and Abpa27, a mouse salivary androgen-binding protein gene that encodes a proteinaceous pheromone (ABP capable of mediating assortative mating, perhaps in conjunction with its bound small lipophilic ligand. The LD we observed is likely a case of association rather than residual physical linkage from a very recent selective sweep, because an intervening gene, Vmn1r71, shows significant intra(subspecific polymorphism but no inter(subspecific divergence in its nucleotide sequence. We discuss alternative explanations of these observations, for example that Abpa27 and Vmn1r67 are coevolving as signal and receptor to reinforce subspecies hybridization barriers or that the unusually divergent Vmn1r67 allele was not a product of fast positive

  6. Stochastic processes and functional analysis a volume of recent advances in honor of M. M. Rao

    CERN Document Server

    Krinik, Alan C

    2004-01-01

    This extraordinary compilation is an expansion of the recent American Mathematical Society Special Session celebrating M. M. Rao's distinguished career and includes most of the presented papers as well as ancillary contributions from session invitees. This book shows the effectiveness of abstract analysis for solving fundamental problems of stochastic theory, specifically the use of functional analytic methods for elucidating stochastic processes, as made manifest in M. M. Rao's prolific research achievements. Featuring a biography of M. M. Rao, a complete bibliography of his published works,

  7. Sujecion de piezas durante las mediciones con M.M.C

    Directory of Open Access Journals (Sweden)

    Miguel Ángel Sellés Cantó

    2012-08-01

    Full Text Available This Coordinate Measuring Machines (C.M.M. has had an increasingly important role throughout history. We are talking to an enterprise-level quality control. A system that is being implemented in all companies, and has developed some tools to control a variety of parameters such as production stabilization.In this paper, we first set out an introduction to the use of C.M.M. as tools for quality control in SME's. Then we explore the importance of piece positioning and clamping before being measured in a C.M.M. We finally analyze four possible moorings, and deviations are obtained. These moorings are designed in order to place the same work piece in the four cases.Finally, the results obtained are compared and show which is the best way to put the part on the C.M.M.

  8. PHILOSOPHY OF CULTURE M.M. BAKHTIN: HISTORICAL AND ANTHROPOLOGICAL DIMENSION

    OpenAIRE

    Spartak Sh. Aytov

    2013-01-01

    The purpose of this paper is to determine the influence of theoretical approaches to the philosophical concepts of culture M. M. Bakhtin on the genesis and implementation of historical and anthropological concepts and renovations mentality and socio-cultural characteristics and behavior of individuals and societies of the past. Methodology. Methodological tools are methods of system and source analyses. Theoretical basis and results: analyzes the concept of the philosophy of culture such M.M....

  9. Modeling and simulation of M/M/c queuing pharmacy system with adjustable parameters

    Science.gov (United States)

    Rashida, A. R.; Fadzli, Mohammad; Ibrahim, Safwati; Goh, Siti Rohana

    2016-02-01

    This paper studies a discrete event simulation (DES) as a computer based modelling that imitates a real system of pharmacy unit. M/M/c queuing theo is used to model and analyse the characteristic of queuing system at the pharmacy unit of Hospital Tuanku Fauziah, Kangar in Perlis, Malaysia. The input of this model is based on statistical data collected for 20 working days in June 2014. Currently, patient waiting time of pharmacy unit is more than 15 minutes. The actual operation of the pharmacy unit is a mixed queuing server with M/M/2 queuing model where the pharmacist is referred as the server parameters. DES approach and ProModel simulation software is used to simulate the queuing model and to propose the improvement for queuing system at this pharmacy system. Waiting time for each server is analysed and found out that Counter 3 and 4 has the highest waiting time which is 16.98 and 16.73 minutes. Three scenarios; M/M/3, M/M/4 and M/M/5 are simulated and waiting time for actual queuing model and experimental queuing model are compared. The simulation results show that by adding the server (pharmacist), it will reduce patient waiting time to a reasonable improvement. Almost 50% average patient waiting time is reduced when one pharmacist is added to the counter. However, it is not necessary to fully utilize all counters because eventhough M/M/4 and M/M/5 produced more reduction in patient waiting time, but it is ineffective since Counter 5 is rarely used.

  10. Anisotropic plasmons, Friedel oscillations, and screening in 8 -P m m n borophene

    Science.gov (United States)

    Sadhukhan, Krishanu; Agarwal, Amit

    2017-07-01

    8 -P m m n borophene is a polymorph of borophene which hosts an anisotropic tilted Dirac cone. Using a low-energy effective Hamiltonian for borophene, we analytically calculate the density-density response function of borophene and study its anisotropic plasmon dispersion and screening properties. We find that the anisotropic plasmon mode in 8 -P m m n borophene remains undamped for higher energies along the mirror symmetry direction. The Friedel oscillation in borophene is found to decay as r-3 in the large-r limit, with both the amplitude as well as the periodicity of the Friedel oscillations being anisotropic.

  11. Performance Analysis and Optimal Allocation of Layered Defense M/M/N Queueing Systems

    Directory of Open Access Journals (Sweden)

    Longyue Li

    2016-01-01

    Full Text Available One important mission of strategic defense is to develop an integrated layered Ballistic Missile Defense System (BMDS. Motivated by the queueing theory, we presented a work for the representation, modeling, performance simulation, and channels optimal allocation of the layered BMDS M/M/N queueing systems. Firstly, in order to simulate the process of defense and to study the Defense Effectiveness (DE, we modeled and simulated the M/M/N queueing system of layered BMDS. Specifically, we proposed the M/M/N/N and M/M/N/C queueing model for short defense depth and long defense depth, respectively; single target channel and multiple target channels were distinguished in each model. Secondly, we considered the problem of assigning limited target channels to incoming targets, we illustrated how to allocate channels for achieving the best DE, and we also proposed a novel and robust search algorithm for obtaining the minimum channel requirements across a set of neighborhoods. Simultaneously, we presented examples of optimal allocation problems under different constraints. Thirdly, several simulation examples verified the effectiveness of the proposed queueing models. This work may help to understand the rules of queueing process and to provide optimal configuration suggestions for defense decision-making.

  12. The M&M Approach: Using Mental and Mechanical Strategies in Teaching and Coaching

    Science.gov (United States)

    Rhea, Chris K.; Wisdom, Stacey

    2007-01-01

    Mental and mechanical (M&M) techniques are very useful in teaching and coaching. Mental techniques are strategies that enhance movement through psychological preparation, such as using imagery to practice a skill. Mechanical techniques are strategies that enhance the physical side of the movement, such as correcting the biomechanics of a golf…

  13. Dalit humanization: A Quest based on M.M. Thomas' theology of salvation and humanization

    NARCIS (Netherlands)

    Rajaiah, J.

    2016-01-01

    Chapter one states the central quest of this thesis: to develop a Dalit theology on the basis of the concepts salvation and humanization of M.M. Thomas. Chapter two elucidates the socio- political and religious milieu which influenced his theology. Thomas’ theology has evolved and developed in

  14. Transient analysis of an M/M/1 queue with multiple vacations

    Directory of Open Access Journals (Sweden)

    Kaliappan Kalidass

    2014-05-01

    Full Text Available In this paper, we have obtained explicit expressions for the time dependent probabilities of the M/M/1  queue with server vacations under a multiple vacation scheme. The corresponding steady state probabilities have been obtained. We also obtain the time dependent performance measures of the systems

  15. Transient analysis of an M/M/1 queue with multiple vacations

    National Research Council Canada - National Science Library

    Kaliappan Kalidass; Kasturi Ramanath

    2014-01-01

    ...; mso-fareast-language: EN-US; mso-bidi-language: AR-SA; mso-no-proof: yes;">In this paper, we have obtained explicit expressions for the time dependent probabilities of the M/M/1 queue with server vacations under a multiple vacation scheme...

  16. Professor M. M. Zagorulko’s school of economic and military history of Russia

    Directory of Open Access Journals (Sweden)

    Redkina Olga Yurievna

    2013-10-01

    Full Text Available Maxim Matveyevich Zagorulko is the first rector of Volgograd State University, the veteran of the Great Patriotic War, the Honorable Citizen of Volgograd. He is the founder and the head of the scientific school studying various aspects of the Fatherland’s history. In the 1960s, M.M. Zagorulko united researches in the field of an economic history of Russia and the Great Patriotic War history. He had chosen as a subject of his doctoral dissertation a history of operation of economy of temporarily occupied territories of the USSR by fascists. In 1970, M.M. Zagorulko in a co-authorship with the Moscow scholar, the active participant of guerrilla movement A.F. Yudenkov published the monograph “Crash of Economic Plans of Fascist Germany on Temporarily Occupied Territory of the USSR”. Soon it was translated into the Czech language. In 1974, there was the second, added and modified edition of the book by M.M. Zagorulko and A.F. Yudenkov – “Crash of the «Oldenburg» Plan”. The third edition of this book was issued in 1980 in the Russian and Czech languages in Moscow and Bratislava. In 1975, Maxim M. Zagorulko defended his doctoral dissertation in the Dissertation Council of Leningrad State University on the subject “Economic Policy of Fascist Germany in the Occupied Territory of the USSR and Its Crash”. M.M. Zagorulko, his pupils and adherents conduct scientific researches in the field of an Economic History of Russia, History of military captivity in the USSR, History of the Battle of Stalingrad and so forth. Under his management multivolume collections of documents were published, monographs were written and dissertations were defended. The fundamental Encyclopedia of the Battle of Stalingrad created by him was declared in 2010 as “The best book of Russia”. In all these projects, theses and monographs M.M. Zagorulko is the organizer and inspirer of scientific researches.

  17. Structural, elastic and electronic properties of C14-type Al{sub 2}M (M=Mg, Ca, Sr and Ba) Laves phases

    Energy Technology Data Exchange (ETDEWEB)

    Lishi, Ma; Yonghua, Duan, E-mail: duanyh@kmust.edu.cn; Runyue, Li

    2017-02-15

    The structural and mechanical properties, Debye temperatures and anisotropic sound velocities of the Laves phases Al{sub 2}M (M=Mg, Ca, Sr and Ba) with C14-type structure were investigated using the first-principles corresponding calculations. The corresponding calculated structural parameters and formation enthalpies are in good agreement with the available theoretical values, and Al{sub 2}Ca has the best phase stability. The mechanical properties, including elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio ν, were deduced within the Voigt-Reuss-Hill approximation. The brittleness and ductility were estimated by the values of Poisson ratio, B/G and Cauchy pressure. Moreover, the elastic anisotropy was investigated by calculating and discussing several anisotropy indexes. Finally, the electronic structures were used to illustrate the bonding characteristics of C14-Al{sub 2}M (M=Mg, Ca, Sr and Ba) phases.

  18. Metal-metal bonds in biology.

    Science.gov (United States)

    Lindahl, Paul A

    2012-01-01

    Nickel-containing carbon monoxide dehydrogenases, acetyl-CoA synthases, nickel-iron hydrogenases, and diron hydrogenases are distinct metalloenzymes yet they share a number of important characteristics. All are O(2)-sensitive, with active-sites composed of iron and/or nickel ions coordinated primarily by sulfur ligands. In each case, two metals are juxtaposed at the "heart" of the active site, within range of forming metal-metal bonds. These active-site clusters exhibit multielectron redox abilities and must be reductively activated for catalysis. Reduction potentials are milder than expected based on formal oxidation state changes. When reductively activated, each cluster attacks an electrophilic substrate via an oxidative addition reaction. This affords a two-electron-reduced substrate bound to one or both metals of an oxidized cluster. M-M bonds have been established in hydrogenases where they serve to initiate the oxidative addition of protons and perhaps stabilize active sites in multiple redox states. The same may be true of the CODH and ACS active sites-Ni-Fe and Ni-Ni bonds in these sites may play critical roles in catalysis, stabilizing low-valence states and initiating oxidative addition of CO(2) and methyl group cations, respectively. In this article, the structural and functional commonalities of these metalloenzyme active sites are described, and the case is made for the formation and use of metal-metal bonds in each enzyme mentioned. As a post-script, the importance of Fe-Fe bonds in the nitrogenase FeMoco active site is discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. PHILOSOPHY OF CULTURE M.M. BAKHTIN: HISTORICAL AND ANTHROPOLOGICAL DIMENSION

    Directory of Open Access Journals (Sweden)

    Spartak Sh. Aytov

    2013-09-01

    Full Text Available The purpose of this paper is to determine the influence of theoretical approaches to the philosophical concepts of culture M. M. Bakhtin on the genesis and implementation of historical and anthropological concepts and renovations mentality and socio-cultural characteristics and behavior of individuals and societies of the past. Methodology. Methodological tools are methods of system and source analyses. Theoretical basis and results: analyzes the concept of the philosophy of culture such M.M. Bakhtin as a carnival, folk culture, culture of humor, doubleworld, concept social-cultural projection material and cultural bottom and its impact on the culture of laughter European Middle Ages and Renaissance. Methodological approaches Bakhtin recreated for historical and anthropological reconstruction mentality and socio-cultural realities of the high Middle Ages and the Renaissance. Investigated the perception of philosophical and cultural concepts M. M. Bakhtin, the scientific community and their impact on the historical and anthropological studies. It was also analyzed the influence of the respective ideas M.M. Bakhtin's historical and anthropological studies of the last quarter of XX - beginning of XXI century. in particular on the work of D. Likhachev, A. Gurevich, E. Thompson and other researchers. Conclusion: concept of the philosophy of culture, MM Bakhtin, in particular, the culture of humor, the popular perception of the world, carnival, social and cultural doubleworld, reconstruction of the domestic foundations of culture laughter Europe era high Middle Ages and the Renaissance were one of the most important conceptual elements in the study of the mentality of socially significant behavior and daily life as these periods, so or any other, from the early Middle Ages to the present.

  20. Transient behaviour of the M/M/2 queue with catastrophes

    Directory of Open Access Journals (Sweden)

    B. Krishna Kumar

    2007-10-01

    Full Text Available This paper presents a transient solution for the system size in the M/M/2 queue with the possibility of catastrophes at the service stations. The state probability of the system size at time t, where the queue starts with any number of customers, in obtained. Asymptotic behaviour of the probability of the server being idle and mean system size are discussed.

  1. Differences in Organizational Structure of Insulin Receptor on Rat Adipocyte and Liver Plasma Membranes: Role of Disulfide Bonds

    Science.gov (United States)

    Schweitzer, John B.; Smith, Robert M.; Jarett, Leonard

    1980-08-01

    Binding of 125I-labeled insulin to rat liver and adipocyte plasma membranes has been investigated after treatment of the membranes with agents that modify disulfide bonds or sulfhydryl groups. Dithiothreitol, a disulfide-reducing agent, produced a bimodal response in adipocyte plasma membranes with dose-dependent increases in binding occurring over the range of 0-1 mM dithiothreitol; 5 mM dithiothreitol produced decreased binding. Insulin binding reached its maximal increase at 1 mM and was 3 times control values. Scatchard analysis of the 1 mM dithiothreitol effect revealed a straight line plot indicative of one class of sites with a Ka of 1.0× 108 M-1 which is intermediate between the two Kas obtained from the curvilinear Scatchard plot of control membranes. There was a 20-fold increase in the number of intermediate-affinity receptors compared to high-affinity receptors. The increased 125I-labeled insulin binding after dithiothreitol treatment was reversed by oxidized glutathione in a dose-dependent manner. Interposition of treatment with N-ethylmaleimide, an alkylating agent, prevented oxidized glutathione from reversing the dithiothreitol effect. Reduced glutathione produced the same effect as dithiothreitol. Liver plasma membranes treated with up to 1 mM dithiothreitol exhibited a maximum increase in insulin binding of 20% compared to control. Dithiothreitol at 5 mM decreased insulin binding below that of control membranes. The results indicate that the dithiothreitol effect on insulin binding to adipocyte plasma membranes is due to disruption of disulfide bonds, and that the structural organization of the insulin receptor on the plasma membranes is different for liver and for adipose tissue. The data imply that the insulin receptors on the plasma membrane of adipocytes possess at least two functionally distinct subclasses of disulfide bond but liver insulin receptors do not.

  2. The M/M/1 queue with inventory, lost sale and general lead times

    DEFF Research Database (Denmark)

    Saffari, Mohammad; Asmussen, Søren; Haji, Rasoul

    We consider an M/M/1 queueing system with inventory under the (r,Q) policy and with lost sales, in which demands occur according to a Poisson process and service times are exponentially distributed. All arriving customers during stockout are lost. We derive the stationary distributions of the joint...... queue length (number of customers in the system) and on-hand inventory when lead times are random variables and can take various distributions. The derived stationary distributions are used to formulate long-run average performance measures and cost functions in some numerical examples....

  3. A New Glow on the Chromatography of M&M Candies

    Science.gov (United States)

    Birdwhistell, Kurt R.; Spence, Thomas G.

    2002-07-01

    This lab experiment for undergraduate or high school students presents the separation and analysis of dyes in the candy shell of M&M chocolate candies. The dyes in the shells of M&Ms are separated using paper chromatography and are identified by comparison of the Rf values, color, and fluorescence properties with those of standard FD&C ([U.S. Federal] Food, Drug, and Cosmetic Act) dyes. The experiment introduces students to chromatography of mixtures, compound identification by using Rf values, and fluorescence. They learn about fluorescence and how it appears in everyday substances and can be used to help identify compounds.

  4. Effect of electron-hole asymmetry on optical conductivity in 8 -P m m n borophene

    Science.gov (United States)

    Verma, Sonu; Mawrie, Alestin; Ghosh, Tarun Kanti

    2017-10-01

    We present a detailed theoretical study of the Drude weight and optical conductivity of 8-P m m n borophene having tilted anisotropic Dirac cones. We provide exact analytical expressions of x x and y y components of the Drude weight as well as maximum optical conductivity. We also obtain exact analytical expressions of the minimum energy (ɛ1) required to trigger the optical transitions and energy (ɛ2) needed to attain maximum optical conductivity. We find that the Drude weight and optical conductivity are highly anisotropic as a consequence of the anisotropic Dirac cone. The optical conductivities have a nonmonotonic behavior with photon energy in the regime between ɛ1 and ɛ2, as a result of the tilted parameter vt. The tilted parameter can be extracted by knowing ɛ1 and ɛ2 from optical measurements. The maximum values of the components of the optical conductivity do not depend on the carrier density and the tilted parameter. The product of the maximum values of the anisotropic conductivities has the universal value (e2/4ℏ ) 2. The tilted anisotropic Dirac cones in 8-P m m n borophene can be realized by the optical conductivity measurement.

  5. A General Strategy for the Synthesis of PtM (M=Fe, Co, Ni) Decorated Three-Dimensional Hollow Graphene Nanospheres for Efficient Methanol Electrooxidation.

    Science.gov (United States)

    Qiu, Xiaoyu; Li, Tiancheng; Deng, Sihui; Cen, Ke; Xu, Lin; Tang, Yawen

    2017-11-02

    A universal sacrificial template-based synthesis strategy was reported to prepare three dimensional (3D) reduced oxide graphene supported PtM (M=Fe, Co, Ni) hollow nanospheres (PtM/RGO HNSs). The inner 3D wrinkle-free graphene skeleton can promote electron and ion kinetics, resulting in enhancement for the permeation of small organic molecule in fuel cells. As inspired by this, the 3D PtM (M=Fe, Co, Ni)/RGO HNSs exhibit clearly enhanced electrocatalytic activity and durability towards the methanol oxidation reaction (MOR) in acidic medium compared with a commercial Pt/C catalyst. This study provides a versatile approach of realizing controlled synthesis of 3D graphene-metal hybrid nanostructures irrespective of the components of the metal domains, and will pave the way for the design of hetero-nanostructures with optimized morphologies and functions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Fluid queues driven by an M/M/1/N queue

    Directory of Open Access Journals (Sweden)

    R. B. Lenin

    2000-01-01

    Full Text Available In this paper, we consider fluid queue models with infinite buffer capacity which receives and releases fluid at variable rates in such a way that the net input rate of fluid into the buffer (which is negative when fluid is flowing out of the buffer is uniquely determined by the number of customers in an M/M/1/N queue model (that is, the fluid queue is driven by this Markovian queue with constant arrival and service rates. We use some interesting identities of tridiagonal determinants to find analytically the eigenvalues of the underlying tridiagonal matrix and hence the distribution function of the buffer occupancy. For specific cases, we verify the results available in the literature.

  7. Optimization of an M/M/1/N Feedback Queue with Retention of Reneged Customers

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar

    2014-01-01

    Full Text Available Customer impatience has become a threat to the business world. Firms employ various customer retention strategies to retain their impatient (or reneged customers. Customer retention mechanisms may help to retain some or all impatient customers. Further, due to unsatisfactory service, customers may rejoin a queue immediately after departure. Such cases are referred to as feedback customers. Kumar and Sharma take this situation into account and study an M/M/1/N feedback queuing system with retention of reneged customers. They obtain only a steady-state solution for this model. In this paper, we extend the work of Kumar and Sharma by performing an economic analysis of the model. We develop a model for the costs incurred and perform the appropriate optimization. The optimum system capacity and optimum service rate are obtained. (original abstract

  8. Effect of ring rotation upon gas adsorption in SIFSIX-3-M (M = Fe, Ni) pillared square grid networks

    Energy Technology Data Exchange (ETDEWEB)

    Elsaidi, Sameh K.; Mohamed, Mona H.; Simon, Cory M.; Braun, Efrem; Pham, Tony; Forrest, Katherine A.; Xu, Wenqian; Banerjee, Debasis; Space, Brian; Zaworotko, Michael J.; Thallapally, Praveen K.

    2017-01-01

    The study of the mobility/rotation of the organic linkers in porous metal-organic frameworks could provide a valuable information about the guest/framework interaction and the factors control the kinetics of adsorption. Here, we analyzed the dynamics of pyrazine ring rotation in a series of pillared square grid frameworks, namely SIFSIX-3-M (M = Fe, Ni). It was found that the rotation of pyrazine ring is influenced by the variation of metal cation, temperature and the guest molecule. The Fe-analogue, [Fe(pz)2(SiF6)2] (pz= Pyrazine), , showed no pronounced ring rotation and exhibited a high affinity toward Xe gas over Kr as exemplified by the sharp Xe uptake at low loading (~0.1 bar) and its high isosteric heat of adsorption (Qst~ 27.4 kJmol-1) compared to the current benchmark materials. The Ni analogue, on the contrary, showed a two-regime adsorption isotherm for Xe with a temperature-dependent inflection point. However, this behavior is not observed with the other gases such as CO2, N2, and Kr which showed one-step adsorption isotherms without any inflection. Using molecular models and simulations, we hypothesize that the inflection point is due to a disordered to ordered transition of the rotational configurations of the pz rings in SIFSIX-3-Ni. These results further support the impact of tuning the pore size and chemistry on the adsorption behavior of porous materials.

  9. Britain exhibition at CERN

    CERN Document Server

    Bertin; CERN PhotoLab

    1969-01-01

    The United Kingdom inaugurated the Industrial Exhibitions in 1968, and it wasn't till 1971 that other countries staged exhibitions at CERN. This photo was taken in 1969, at the second British exhibition, where 16 companies were present.

  10. Peace-Making Ideas by M.M. Kovalevsky at the Beginning of 20th Century

    Directory of Open Access Journals (Sweden)

    NIKOLAEV N.Yu.

    2014-09-01

    Full Text Available The article reveals the peace-making ideas of famous historian, sociologist and lawyer M.M. Kovalevsky at the beginning of 20th century and analyzes the sociological conception of solidarity which served as the basis for his views on war and peace. He considered social progress as broadening of solidarity sphere which was unavoidably promoted to the consciousness of political integration society. The scientist approximately compared the progress with concentric circles which embodied of uninterruptedly widing human solidarity. The final stage of social and political development should be the creation of national and federal unions, which in their turn would unify in international union. The union built on the principles of democracy and observance of international right standards was destined not only to keep and to ensure the common peace, but also to promote the development of international trade and industry. Kovalevsky played important role in building the peace-making movement in Russia by supporting it with his high scientific and moral authority. In particular, he headed the St. Petersburg’s peace society, established in 1909. Besides, there were a lot of contradictions in his peaceful views. Being the patriot and supporter of the state, the scientist was very far from peace when Russian national interests were taken ino account. This contradiction was clearly revealed during Balkan’s conflict (1912-1913 and the First World War.

  11. Nonenzymatic glucose sensor based on ultrasonic-electrodeposition of bimetallic PtM (M=Ru, Pd and Au) nanoparticles on carbon nanotubes-ionic liquid composite film.

    Science.gov (United States)

    Xiao, Fei; Zhao, Faqiong; Mei, Deping; Mo, Zhirong; Zeng, Baizhao

    2009-08-15

    We report here for the first time on the fabrication of highly dispersed PtM (M=Ru, Pd and Au) nanoparticles on composite film of multi-walled carbon nanotubes (MWNTs)-ionic liquid (IL, i.e., trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide) by using ultrasonic-electrodeposition method. The PtM nanoparticles are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction, and we find that they are well-dispersed and exhibit alloy properties. Electrochemical experiments show that the PtRu(1:1, i.e., ratio of c(H(2)PtCl(6))/c(RuCl(3)))-MWNT-IL nanocomposite modified glassy carbon electrode (PtRu(1:1)-MWNT-IL/GCE) has smaller electron transfer resistance and larger active surface area than PtRu(1:1)/GCE, PtRu(1:1)-MWNT/GCE, PtPd(1:1)-MWNT-IL/GCE and PtAu(1:1)-MWNT-IL/GCE. The PtRu(1:1)-MWNT-IL/GCE also presents stronger electrocatalytic activity toward the glucose oxidation than other electrodes. At -0.1 V, the electrode responds linearly to glucose up to 15 mM in neutral media, with a detection limit of 0.05 mM (S/N=3) and detection sensitivity of 10.7 microA cm(-2)mM(-1). Meanwhile, the interference of ascorbic acid, uric acid, acetamidophenol and fructose is effectively avoided. The as-made sensor was applied to the determination of glucose in serum and urine samples. The results agreed closely with the results obtained by a hospital. This novel nonenzyme sensor thus has potential application in glucose detection.

  12. Reactions of Metal-Metal Multiple Bonds. 14. Synthesis and Characterization of Triangulo-W3 and Mo2W-oxo Capped Alkoxide Clusters. Comproportionation of M-M Triple Bonds, sigma(2)pi(4) and d(o) Metal-oxo Groups: M Triple Bond M + M Triple Bond O Yields M3(micron 3-O).

    Science.gov (United States)

    1984-05-02

    the spectra are quite similar consisting of two or more weak bands in the visible region and one or more very intense transitions in the UV region...The weak bands in the visible region were previously assigned for M030(O-i- 17 Pr)1 0 as arising from transitions between metal centered orbitals, with

  13. Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) Alloys for the Hydrogen Separation Membrane.

    Science.gov (United States)

    Nayebossadri, Shahrouz; Speight, John D; Book, David

    2017-01-25

    Self-supported fcc Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) alloys were studied as potential hydrogen purification membranes. The effects of small additions (1-2.6 at. %) of these elements on the structure, hydrogen solubility, diffusivity, and permeability were examined. Structural analyses by X-ray diffraction (XRD) showed the fcc phase for all alloys with induced textures from cold rolling. Heat treatment at 650 °C for 96 h led to the reorientation in all alloys except the Pd-Cu-Zr alloy, exhibiting the possibility to enhance the structural stability by Zr addition. Hydrogen solubility was almost doubled in the ternary alloys containing Y and Zr compared to Pd65.1Cu34.9 alloy at 300 °C. It was noted that hydrogen diffusivity is decreased upon additions of these elements compared to the Pd65.1Cu34.9 alloy, with the Pd-Cu-Zr alloy showing the lowest hydrogen diffusivity. However, the comparable hydrogen permeability of the Pd-Cu-Zr alloy with the corresponding binary alloy, as well as its highest hydrogen permeability among the studied ternary alloys at temperatures higher than 300 °C, suggested that hydrogen permeation of these alloys within the fcc phase is mainly dominated by hydrogen solubility. Hydrogen flux variations of all ternary alloys were studied and compared with the Pd65.1Cu34.9 alloy under 1000 ppm of H2S + H2 feed gas. Pd-Cu-Zr alloy showed superior resistance to the sulfur poisoning probably due to the less favorable H2S-surface interaction and more importantly slower rate of bulk sulfidation as a result of improved structural stability upon Zr addition. Therefore, Pd-Cu-Zr alloys may offer new potential hydrogen purification membranes with improved chemical stability and hydrogen permeation compared to the binary fcc Pd-Cu alloys.

  14. Digital collections and exhibits

    CERN Document Server

    Denzer, Juan

    2015-01-01

    Today's libraries are taking advantage of cutting-edge technologies such as flat panel displays using touch, sound, and hands-free motions to design amazing exhibits using everything from simple computer hardware to advanced technologies such as the Microsoft Kinect. Libraries of all types are striving to add new interactive experiences for their patrons through exciting digital exhibits, both online and off. Digital Collections and Exhibits takes away the mystery of designing stunning digital exhibits to spotlight library trea

  15. Ethics on Exhibit

    Science.gov (United States)

    Vick, Randy M.

    2011-01-01

    This article discusses ethical questions raised by an exhibition of work by an artist with a history of mental illness and the exhibition's relevance to art therapy and “outsider art” discourse on the subject. Considerations for how such an exhibit could be handled had the circumstances included an art therapist and art therapy client are…

  16. Hydrogen bonded supramolecular materials

    CERN Document Server

    Li, Zhan-Ting

    2015-01-01

    This book is an up-to-date text covering topics in utilizing hydrogen bonding for constructing functional architectures and supramolecular materials. The first chapter addresses the control of photo-induced electron and energy transfer. The second chapter summarizes the formation of nano-porous materials. The following two chapters introduce self-assembled gels, many of which exhibit unique functions. Other chapters cover the advances in supramolecular liquid crystals and the versatility of hydrogen bonding in tuning/improving the properties and performance of materials. This book is designed

  17. 7 CFR Exhibit G to Subpart A of... - Performance Bond

    Science.gov (United States)

    2010-01-01

    ... PROGRAM REGULATIONS CONSTRUCTION AND REPAIR Planning and Performing Construction and Other Development Pt... Principal (Address) By _____(s) (Address) Surety ATTEST: Witness as to Surety (Address) By Attorney-in Fact...

  18. Visitors Center Exhibits

    Science.gov (United States)

    1997-01-01

    A child enjoys building his own LEGO model at a play table which was included in the exhibit 'Travel in Space' World Show. The exhibit consisted of 21 displays designed to teach children about flight and space travel from the Wright brothers to future generations of space vehicles.

  19. Sonnesgade 11 - Exhibition

    DEFF Research Database (Denmark)

    Carbone, Claudia; Toft, Anne Elisabeth

    2013-01-01

    This exhibition consists of site specific installations; a collection of work by students from Studio Constructing an Archive at the Aarhus School of Architecture, and SLETH Architects. The exhibition showcases the culmination of a common project which began in February 2013. The project has been...

  20. Exhibition in Sight

    Science.gov (United States)

    Wasserman, Burton

    1977-01-01

    The traveling exhibition titled "The Wild Beasts: Fauvism and its Affinities" opened first at the Museum of Modern Art in New York City and was then moved to the San Francisco Museum of Modern Art in 1976. Discusses the exhibition's historic value, how Fauvism passed through three fairly distinct stylistic phases, and the social…

  1. Space physics exhibits underway

    Science.gov (United States)

    DeVito, M. Catherine

    AGU is planning a new space science exhibit for the Smithsonian Institution's National Air and Space Museum in Washington that will help visitors come to an understanding of space science as a comprehensive, interdisciplinary, and exciting field. The title of the exhibit is “Electric Space: Our Earth-Sun Environment.” The exhibit's five modules will include demonstrations of the effects of particle and field radiation on humans and satellites in space and on human technology on the ground. The project also includes a larger traveling version that will visit science and technology centers throughout the United States. The first exhibit is planned to open at the Air and Space Museum in late summer or early fall 1992, in time for International Space Year activities; the traveling exhibit will begin touring in early 1993.

  2. An iron-capped metal-organic polyyne: {[Fe](C[triple bond]C)2[W][triple bond]CC[triple bond]CC[triple bond][W](C[triple bond]C)2[Fe]}.

    OpenAIRE

    Semenov Sergey N; Taghipourian Shiva F; Blacque Olivier; Fox Thomas; Venkatesan Koushik; Berke Heinz

    2010-01-01

    The organometallic conjugated complex H(C[triple bond]C)(2)[W][triple bond]CC[triple bond]CC[triple bond][W](C[triple bond]C)(2)H {[W] = W(dppe)(2); dppe = 12 bis(diphenylphosphino)ethane} containing a ditungstenatetradecaheptayne unit was synthesized by utilizing a new and efficient coupling method. The stannylated derivative was converted to the tetranuclear complex which exhibits efficient long range electron transfer.

  3. Communicating Science through Exhibitions

    Science.gov (United States)

    Dusenbery, Paul

    2005-04-01

    It is critically important for the public to better understand the scientific process. Museum exhibitions are an important part of informal science education that can effectively reach public audiences as well as school groups. They provide an important gateway for the public to learn about compelling scientific endeavors. Science exhibitions also provide a marvelous opportunity for scientists to become engaged in the exhibit development process. The Space Science Institute (SSI) is a national leader in producing traveling science exhibitions and their associated educational programming (i.e. interactive websites, educator workshops, public talks, instructional materials). The focus of this presentation will be on two of its exhibit projects: MarsQuest (on tour for four years) and Alien Earths (its tour began early in 2005). MarsQuest is enabling millions of Americans to share in the excitement of the scientific exploration of Mars and to learn more about their own planet in the process. Alien Earths will bring origins-related research and discoveries to students and the American public. It has four interrelated exhibit areas: Our Place in Space, Star Birth, Planet Quest, and Search for Life. Exhibit visitors will explore the awesome events surrounding the birth of stars and planets; they will join scientists in the hunt for planets outside our solar system including those that may be in ``habitable zones'' around other stars; and finally they will be able to learn about how scientists are looking for signs of life beyond Earth. SSI is also developing interactive web sites based on exhibit themes. New technologies are transforming the Web from a static medium to an interactive environment with tremendous potential for informal education and inquiry-based investigations. This talk will focus on the role informal science projects play in effectively communicating science to a broad, public audience.

  4. A simple coordination complex exhibiting colour change on slight ...

    Indian Academy of Sciences (India)

    Administrator

    gens (from two OPDA ligands) that define equato- rial positions and the axial positions are filled by the nitrogen atoms coming from two different thiocy- anate ligands (figure 1). The thiocyanate ligands generally exhibit different binding modes in its metal complexes like S-bonded, N-bonded, bridging or ionic, etc. 19.

  5. Facial synthesis of PtM (M = Fe, Co, Cu, Ni) bimetallic alloy nanosponges and their enhanced catalysis for oxygen reduction reaction.

    Science.gov (United States)

    Zhu, Zhijun; Zhai, Yanling; Dong, Shaojun

    2014-10-08

    Constructing electrocatalysts with enhanced activity and stability is necessary due to the increasing demands of the fuel cell industry. This work demonstrates a facile approach to synthesize well-defined three-dimensional (3D) PtM (M = Fe, Co, Cu, Ni) bimetallic alloy nanosponges (BANs) in the presence of Al. Significantly, with the aid of Al, the as-prepared BANs exhibit greatly enhanced electrochemistry catalytic activity in an oxygen reduction reaction (ORR), and PtFe BANs appear the best ORR property among the four BANs and commercial Pt/C catalysts. This work may provide a universal approach for convenient and large-scale fabrication of porous bimetallic nanocatalysts, thus providing promising potential application as an efficient cathodic component in fuel cells for industrial production.

  6. Epitaxial Growth of Multimetallic Pd@PtM (M = Ni, Rh, Ru) Core-Shell Nanoplates Realized by in Situ-Produced CO from Interfacial Catalytic Reactions.

    Science.gov (United States)

    Yan, Yucong; Shan, Hao; Li, Ge; Xiao, Fan; Jiang, Yingying; Yan, Youyi; Jin, Chuanhong; Zhang, Hui; Wu, Jianbo; Yang, Deren

    2016-12-14

    Pt-based multimetallic core-shell nanoplates have received great attention as advanced catalysts, but the synthesis is still challenging. Here we report the synthesis of multimetallic Pd@PtM (M = Ni, Rh, Ru) nanoplates including Pd@Pt nanoplates, in which Pt or Pt alloy shells with controlled thickness epitaxially grow on plate-like Pd seeds. The key to achieve high-quality Pt-based multimetallic nanoplates is in situ generation of CO through interfacial catalytic reactions associated with Pd nanoplates and benzyl alcohol. In addition, the accurate control in a trace amount of CO is also of great importance for conformal growth of multimetallic core-shell nanoplates. The Pd@PtNi nanoplates exhibit substantially improved activity and stability for methanol oxidation reaction (MOR) compared to the Pd@Pt nanoplates and commercial Pt catalysts due to the advantages arising from plate-like, core-shell, and alloy structures.

  7. Hydrogen Bonding to Alkanes: Computational Evidence

    DEFF Research Database (Denmark)

    Hammerum, Steen; Olesen, Solveig Gaarn

    2009-01-01

    The structural, vibrational, and energetic properties of adducts of alkanes and strong cationic proton donors were studied with composite ab initio calculations. Hydrogen bonding in [D-H+ H-alkyl] adducts contributes to a significant degree to the interactions between the two components, which...... is substantiated by NBO and AIM results. The hydrogen bonds manifest themselves in the same manner as conventional hydrogen bonds, D-H bond elongation, D-H vibrational stretching frequency red shift and intensity increase, and adduct stabilization. The alkane adducts also exhibit elongation of the C-H bonds...... involved and a concurrent red shift, which is rationalized in terms of charge-transfer interactions that cause simultaneous weakening of both the O-H and C-H bonds. Like other dihydrogen-bonded adducts, the adducts possess a bent structure and asymmetric bifurcated hydrogen bonds. The hydrogen bonds...

  8. Council Chamber exhibition

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    To complete the revamp of CERN’s Council Chamber, a new exhibition is being installed just in time for the June Council meetings.   Panels will showcase highlights of CERN’s history, using some of the content prepared for the exhibitions marking 50 years of the PS, which were displayed in the main building last November. The previous photo exhibition in the Council Chamber stopped at the 1970s. To avoid the new panels becoming quickly out of date, photos are grouped together around specific infrastructures, rather than following a classic time-line. “We have put the focus on the accelerators – the world-class facilities that CERN has been offering researchers over the years, from the well-known large colliders to the lesser-known smaller facilities,” says Emma Sanders, who worked on the content. The new exhibition will be featured in a future issue of the Bulletin with photos and an interview with Fabienne Marcastel, designer of the exhibit...

  9. EXHIBITION: Accelerated Particles

    CERN Multimedia

    2004-01-01

    An exhibition of plastic arts and two evenings of performances by sound and visual artists as part of CERN's 50th anniversary celebrations. Fifty candles for CERN, an international laboratory renowned for fundamental research, is a cause for celebration. Since March this year, Geneva and neighbouring parts of France have been the venues for a wealth of small and large-scale events, which will continue until November. Given CERN's location in the commune of Meyrin, the ForuMeyrin is hosting exhibitions of plastic arts and performances entitled: Accelerated Particles. Several works will be exhibited and performed in two 'salons'. Salon des matières: An exhibition of plastic arts From Tues 12 October to Wed 3 November 2004 Tuesdays to Fridays: 16:00 to 19:00 Saturdays: 14:00 to 18:00 Exhibition open late on performance nights, entrance free Salon des particules: Musical and visual performances Tues 12 and Mon 25 October from 20:00 to 23:00 Preview evening for both events: Tues 12 October from 18:...

  10. Exhibition in Sight

    Science.gov (United States)

    Wasserman, Burton

    1978-01-01

    Ludwig Mies van der Rohe is known primarily as an architect. However, he also designed chairs and tables. Discusses an exhibit held in New York City a few months ago which showed how well the famous architect achieved his goals in the area of furniture design. (Author/RK)

  11. EXHIBITION: Accelerated Particles

    CERN Multimedia

    2004-01-01

    http://www.cern.ch/cern50/ An exhibition of plastic arts and two evenings of performances by sound and visual artists as part of CERN's fiftieth anniversary celebrations. The fiftieth anniversary of a world famous organization like CERN, an international laboratory specializing in fundamental research, is a cause for celebration. Since March this year, Geneva and neighbouring parts of France have been the venues for a wealth of small and large-scale events, which will continue until November. Given CERN's location in the commune of Meyrin, the ForuMeyrin is hosting two "salons" consisting of an exhibition of plastic arts and evenings of music and visual arts performances with the collective title of "Accelerated Particles". Several works will be exhibited and performed. Salon des matières: An exhibition of plastic arts Until Wednesday 3 November 2004. Tuesdays to Fridays: 4.00 p.m. to 7.00 p.m. Saturdays: 2.00 p.m. to 6.00 p.m. Doors open late on the evening of the performances. Salon des ...

  12. Fayez M M Semida

    African Journals Online (AJOL)

    ABSTRACT. Nesting behaviour of the solitary, spring-emerging, univoltine, ground-nesting bee, Anthophora pauperata Walker (Anthophoridae), was studied in the semi-arid mountainous environment of. Wadi El Arbaein, St. Katherine, S. Sinai, Egypt, during spring and summer 1996 - 1998. Female. A. pauperata tend to ...

  13. CERN permanent exhibitions

    CERN Multimedia

    2016-01-01

    Explore by yourself the issues CERN's physicists are trying to solve: given that the entire universe is made of particles, where do they come from? Why do they behave in the way they do? Discover the massive apparatus used by physicists at CERN, like the LHC, and see how each part works. And if you have more time on site, follow the LHC circuit at ground level to understand in situ this giant machine. Enter our exhibitions. Welcome!

  14. Upcycling CERN Exhibitions

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    Summer is coming - and with it, a new Microcosm exhibition showcasing CERN (see here). But while the new exhibit is preparing to enchant visitors, many have been asking about the site's former content. Will it simply be out with the old and in with the new? Not as such!   The plasma ball from Microcosm is now on display at the LHCb site. As Microcosm's new content is moving in, its old content is moving up. From LHCb to IdeaSquare, former Microcosm displays and objects are being installed across the CERN site. "Microcosm featured many elements that were well suited to life outside of the exhibition," says Emma Sanders, Microcosm project leader in the EDU group. "We didn't want this popular content to go to waste, and so set out to find them new homes across CERN." The LHCb experiment has received a number of Microcosm favourites, including the Rutherford experiment, the cosmic ray display and the Thomson experiment. "We&...

  15. Online Exhibits & Concept Maps

    Science.gov (United States)

    Douma, M.

    2009-12-01

    Presenting the complexity of geosciences to the public via the Internet poses a number of challenges. For example, utilizing various - and sometimes redundant - Web 2.0 tools can quickly devour limited time. Do you tweet? Do you write press releases? Do you create an exhibit or concept map? The presentation will provide participants with a context for utilizing Web 2.0 tools by briefly highlighting methods of online scientific communication across several dimensions. It will address issues of: * breadth and depth (e.g. from narrow topics to well-rounded views), * presentation methods (e.g. from text to multimedia, from momentary to enduring), * sources and audiences (e.g. for experts or for the public, content developed by producers to that developed by users), * content display (e.g. from linear to non-linear, from instructive to entertaining), * barriers to entry (e.g. from an incumbent advantage to neophyte accessible, from amateur to professional), * cost and reach (e.g. from cheap to expensive), and * impact (e.g. the amount learned, from anonymity to brand awareness). Against this backdrop, the presentation will provide an overview of two methods of online information dissemination, exhibits and concept maps, using the WebExhibits online museum (www.webexhibits.org) and SpicyNodes information visualization tool (www.spicynodes.org) as examples, with tips on how geoscientists can use either to communicate their science. Richly interactive online exhibits can serve to engage a large audience, appeal to visitors with multiple learning styles, prompt exploration and discovery, and present a topic’s breadth and depth. WebExhibits, which was among the first online museums, delivers interactive information, virtual experiments, and hands-on activities to the public. While large, multidisciplinary exhibits on topics like “Color Vision and Art” or “Calendars Through the Ages” require teams of scholars, user interface experts, professional writers and editors

  16. Smithsonian climate change exhibits

    Science.gov (United States)

    Kumar, Mohi

    2006-05-01

    Two new museum exhibits, ``Arctic: A Friend Acting Strangely'' and ``Atmosphere: Change is in the Air'' opened 15 April at the Smithsonian Institution's National Museum of Natural History in Washington, D.C., in partnership with the U.S. National Oceanic and Atmospheric Administration, NASA, and the U.S. National Science Foundation. In ``Arctic: A Friend Acting Strangely,'' anecdotes from indigenous polar people reveal how climate changes have affected life within the last 50 years. For example, as permafrost melts and sea ice shrinks, plant distributions and animal migration patterns are changing, severely affecting culture.

  17. [Introgression of nuclear and mitochondrial DNA markers of Mus musculus musculus to aboriginal populations of wild mice from central Asia (M. m. wagneri) and south Siberia (M. m. gansuensis)].

    Science.gov (United States)

    Spiridonova, L N

    2014-01-01

    Variability of the nucleotide sequences of the second intron of the b1-chain of hemoglobin (Hbb-b1) and complete control region of mitochondrial DNA (D-loop) was studied in aboriginal and commensal populations of M. m. wagneri from Central Asia and M. m. gansuensis from South Siberia. A difference in frequency of the hemoglobin Hbb(w1) type for natural and urban populations of mice was shown. All mice from natural habitats of studied areas kept musculus-type of mtDNA. Apparently, the substitution of taxonpecific mitochondrial haplotypes of wagneri and gansuensis might occur due to absorbing hybridization with nominate subspecies musculus, what is consistent with the results on nuclear DNA (Hbb-b1 gene) of this work. Two differentiated haplo groups among aboriginal subspecies wagneri were discovered first time (d = 0.01), one of which included house mice from Turkmenistan. This may indicate on mtDNA introgression from commensal forms of Turkmenistan into natural populations of Kazakhstan mice. The castaneus-type of mtDNA was detected in two individuals from the natural habitat of Kazakhstan and Turkmenistan, it had not been met in Central Asia before. It is suggested that the gene flow of nuclear and mitochondrial genomes in microevolution processes in M. musculus is directed from the commensal forms towards wild populations.

  18. Transient solution of an M/M/1 vacation queue with a waiting server and impatient customers

    Directory of Open Access Journals (Sweden)

    Sherif I. Ammar

    2017-07-01

    Full Text Available Recently, Ammar [1] has discussed the transient behavior of a multiple vacations queue with impatient customers. In this paper, a similar technique is used to derive a new elegant explicit solution for an M/M/1 vacation queue with impatient customers and a waiting server, where the server is allowed to take a vacation whenever the system is empty after waiting for a random period of time. If the server does not return from the vacation before the expiry of the customer impatience time, the customer abandons the system forever. Moreover, the formulas of mean and variance expressed in terms of the obtained possibilities for this model.

  19. Anniversary Exhibition. Nechvolodov.

    Directory of Open Access Journals (Sweden)

    - -

    2006-03-01

    Full Text Available On the 10th of August, 2005 in Tartu (the second biggest educational and cultural city in Estonia Stanislav Nechvolodov's exhibition was opened to show the 5-year cycle of his work, traditional for the author and his admirers. At the opening ceremony Nechvolodov said that the exhibition was the last one and appointed on his 70th anniversary.The architectural and building society in Irkutsk remembers Stanislav Nechvolodov as an architect working on dwelling and civil buildings in 1960-70s. Below are some extracts from the Estonian press.«Postimees» newspaper, December 1993. The interview «Expressionistic naturalist, conservative Nechvolodov» by journalist Eric Linnumyagi. He asks about all the details and describes the troubles experienced by Nechvolodov during the perestroika period in Estonia, for example: the Tartu University refused to install the sculpture of Socrat, the art school refused to engage him as an instructor, the sculpture of Socrat moved to Vrotzlav, Poland, and Nechvolodov moved to Poland to read lectures there.«Tartu» newspaper, November 2000. Mats Oun, artist, says in the article «Nechvolodov: a man of Renaissance»: «Nechvolodov works in Estonia, his works are placed in many local and foreign museums. Regardless some insignificant faults, he deserves a high estimation, and his manysided open exhibition can be an example for other artists. He is a man of Renaissance».

  20. Bimetallic PtM (M=Pd, Ir) nanoparticle decorated multi-walled carbon nanotube enzyme-free, mediator-less amperometric sensor for H₂O₂.

    Science.gov (United States)

    Chen, Kuan-Jung; Chandrasekara Pillai, K; Rick, John; Pan, Chun-Jern; Wang, Shih-Han; Liu, Chung-Chiun; Hwang, Bing-Joe

    2012-03-15

    A new highly catalytic and intensely sensitive amperometric sensor based on PtM (where M=Pd, Ir) bimetallic nanoparticles (NPs) for the rapid and accurate estimation of hydrogen peroxide (H(2)O(2)) by electrooxidation in physiological conditions is reported. PtPd and PtIr NPs-decorated multiwalled carbon nanotube nanocatalysts (PtM/MWCNTs) were prepared by a modified Watanabe method, and were characterized by XRD, TEM, ICP, and XAS. The sensors were constructed by immobilizing PtM/MWCNTs nanocatalysts in a Nafion film on a glassy carbon electrode. Both PtPd/MWCNTs and PtIr/MWCNTs assemblies catalyzed the electrochemical oxidation of H(2)O(2). Cyclic voltammetry characterization measurements revealed that both the PtM (M=Pd, Ir)/MWCNTs/GCE possessed similar electrochemical surface areas (∼0.55 cm(2)), and electron transfer rate constants (∼1.23 × 10(-3)cms(-1)); however, the PtPd sensor showed a better performance in H(2)O(2) sensing than did the PtIr counterpart. Explanations were sought from XAS measurements to explain the reasons for differences in sensor activity. When applied to the electrochemical detection of H(2)O(2), the PtPd/MWCNTs/GC electrode exhibited a low detection limit of 1.2 μM with a wide linear range of 2.5-125 μM (R(2)=0.9996). A low working potential (0V (SCE)), fast amperometric response (<5s), and high sensitivity (414.8 μA mM(-1)cm(-2)) were achieved at the PtPd/MWCNTs/GC electrode. In addition, the PtPd/MWCNTs nanocatalyst sensor electrode also exhibited excellent reproducibility and stability. Along with these attractive features, the sensor electrode also displayed very high specificity to H(2)O(2) with complete elimination of interference from UA, AA, AAP and glucose. Copyright © 2012. Published by Elsevier B.V.

  1. Hydrogen bonding in tight environments

    DEFF Research Database (Denmark)

    Pirrotta, Alessandro; Solomon, Gemma C.; Franco, Ignacio

    2016-01-01

    The single-molecule force spectroscopy of a prototypical class of hydrogen-bonded complexes is computationally investigated. The complexes consist of derivatives of a barbituric acid and a Hamilton receptor that can form up to six simultaneous hydrogen bonds. The force-extension (F-L) isotherms...... of the host-guest complexes are simulated using classical molecular dynamics and the MM3 force field, for which a refined set of hydrogen bond parameters was developed from MP2 ab initio computations. The F-L curves exhibit peaks that signal conformational changes during elongation, the most prominent...... of which is in the 60-180 pN range and corresponds to the force required to break the hydrogen bonds. These peaks in the F-L curves are shown to be sensitive to relatively small changes in the chemical structure of the host molecule. Thermodynamic insights into the supramolecular assembly were obtained...

  2. A novel class of compounds--superalkalides: M⁺(en)₃M'₃O⁻ (M, M' = Li, Na, and K; en = ethylenediamine)-with excellent nonlinear optical properties and high stabilities.

    Science.gov (United States)

    Mai, Jinmei; Gong, Shida; Li, Nan; Luo, Qiong; Li, Zhiru

    2015-11-21

    With the aid of ab initio calculations at the MP2 level of theory, we designed a novel class of inorganic salts, M(+)(en)3M3'O(-) (M, M' = Li, Na, and K), by using the M3'O superalkalis. These compounds are the first examples of inorganic salts wherein the superalkali occupies the anionic site, and termed superalkalides. The electronic structural features of the M(+)(en)3M3'O(-) superalkalides are very similar to those of the corresponding M(+)(en)3M'(-) alkalides which have been reported by Zurek (J. Am. Chem. Soc., 2011, 133, 4829). In this study, the calculated NLO properties of M(+)(en)3M3'O(-) and M(+)(en)3M'(-) (M, M' = Li, Na, and K) show that both superalkalides and alkalides have significantly large first hyperpolarizabilities (β0) with the values in the range of 7.80 × 10(3) to 9.16 × 10(4) a.u. and 7.95 × 10(3) to 1.84 × 10(5) a.u., respectively. Computations on the stabilities of M(+)(en)3M3'O(-) and M(+)(en)3M'(-) demonstrate that the M(+)(en)3M3'O(-) superalkalides are preferably stable than the corresponding M(+)(en)3M'(-) alkalides because of the presence of hydrogen bonds in M(+)(en)3M3'O(-). Therefore, the designed superalkalides, M(+)(en)3M3'O(-) (M, M' = Li, Na, and K), with excellent nonlinear optical properties and high stabilities are greatly promising candidates for NLO materials. We hope that this article could attract more research interest in superatom chemistry and for further experimental research.

  3. Noncovalent synthesis using hydrogen bonding

    NARCIS (Netherlands)

    Prins, L.J.; Reinhoudt, David; Timmerman, P.

    2001-01-01

    Hydrogen bonds are like human beings in the sense that they exhibit typical grouplike behavior. As an individual they are feeble, easy to break, and sometimes hard to detect. However, when acting together they become much stronger and lean on each other. This phenomenon, which in scientific terms is

  4. Chemistry of the M (M=Fe, Ca, Ba-Se-H2O Systems at 25 °C

    Directory of Open Access Journals (Sweden)

    Fumihiko Hasegawa

    2009-09-01

    Full Text Available The chemistry of the M (M=Fe, Ca, Ba-Se-H2O systems at 25 °C is reviewed based on our previous papers. In this paper, the phase equilibria in the Fe(III-Se(IV-H2O, Ca-Se(IV,VI-H2O and Ba-Se(IV,VI-H2O systems at 25 °C are discussed. Then, the three-stage process for removal of selenium from industrial waste water [Se(IV,VI < 1,500 mg/L] containing sulfuric acid was introduced. This seems to be a promising process for selenium removal from acidic sulfate waste water containing high concentration levels of selenium to below 0.1 mg/L.

  5. Pricing in M/M/1 queues when cost of waiting in queue differs from cost of waiting in service

    Directory of Open Access Journals (Sweden)

    Görkem Sarıyer

    2016-11-01

    Full Text Available Service providers can adjust the entrance price to the state of the demand in real life service systems where the customers' decision to receive the service, is based on this price, state of demand and other system parameters. We analyzed service provider's short and long term pricing problems in unobservable M/M/1 queues having the rational customers, where, for customers, the unit cost of waiting in the queue is higher than unit cost of waiting in the service. We showed that waiting in the queue has a clear negative effect on customers’ utilities, hence the service provider's price values. We also showed that, in the short term, monopolistic pricing is optimal for congested systems with high server utilization levels, whereas in the long term, market capturing pricing is more profitable.

  6. Bonding over Dentin Replacement Materials.

    Science.gov (United States)

    Meraji, Naghmeh; Camilleri, Josette

    2017-08-01

    Dentin replacement materials are necessary in large cavities to protect the pulp and reduce the bulk of filling material. These materials are layered with a composite resin restorative material. Microleakage caused by poor bonding of composite resin to underlying dentin replacement material will result in pulp damage. The aim of this study was to characterize the interface between dentin replacement materials and composite resin and to measure the shear bond strength after dynamic aging. Biodentine (Septodont, Saint Maur-des-Fosses, France), Theracal LC (Bisco, Schaumburg, IL), and Fuji IX (GC, Tokyo, Japan) were used as dentin replacement materials. They were then overlaid with a total-etch and bonding agent or a self-etch primer and composite resin or a glass ionomer cement. All combinations were thermocycled for 3000 cycles. The interface was characterized using scanning electron microscopy and elemental mapping. Furthermore, the shear bond strength was assessed. The Biodentine surface was modified by etching. The Theracal LC and Fuji IX microstructure was unchanged upon the application of acid etch. The Biodentine and glass ionomer interface showed an evident wide open space, and glass particles from the glass ionomer adhered to the Biodentine surface. Elemental migration was shown with aluminum, barium, fluorine, and ytterbium present in Biodentine from the overlying composite resin. Calcium was more stable. The bond strength between Theracal LC and composite using a total-etch technique followed by self-etch primer achieved the best bond strength values. Biodentine exhibited the weakest bond with complete failure of bonding shown after demolding and thermocycling. Dynamic aging is necessary to have clinically valid data. Bonding composite resin to water-based dentin replacement materials is still challenging, and further alternatives for restoration of teeth using such materials need to be developed. Copyright © 2017 American Association of Endodontists

  7. Understanding Bonds - Denmark

    DEFF Research Database (Denmark)

    Rimmer, Nina Røhr

    2016-01-01

    a specified rate of interest during the life of the bond and to repay the face value of the bond (the principal) when it “matures,” or comes due. Among the types of bonds you can choose from are: Government securities, municipal bonds, corporate bonds, mortgage and asset-backed securities, federal agency...

  8. Bidirectional multi-optical line terminals incorporated converged WSN-PON network using M/M/1 queuing

    Science.gov (United States)

    Kumar, Love; Sharma, Vishal; Singh, Amarpal

    2017-12-01

    Wireless Sensor Networks (WSNs) have an assortment of application areas, for instance, civil, military, and video surveillance with restricted power resources and transmission link. To accommodate the massive traffic load in hefty sensor networks is another key issue. Subsequently, there is a necessity to backhaul the sensed information of such networks and prolong the transmission link to access the distinct receivers. Passive Optical Network (PON), a next-generation access technology, comes out as a suitable candidate for the convergence of the sensed data to the core system. The earlier demonstrated work with single-OLT-PON introduces an overloaded buffer akin to video surveillance scenarios. In this paper, to combine the bandwidth potential of PONs with the mobility capability of WSNs, the viability for the convergence of PONs and WSNs incorporating multi-optical line terminals is demonstrated to handle the overloaded OLTs. The existing M/M/1 queue theory with interleaving polling with adaptive cycle time as dynamic bandwidth algorithm is used to shun the probability of packets clash. Further, the proposed multi-sink WSN and multi-OLT PON converged structure is investigated in bidirectional mode analytically and through computer simulations. The observations establish the proposed structure competent to accommodate the colossal data traffic through less time consumption.

  9. Chemical Bonds II

    Science.gov (United States)

    Sanderson, R. T.

    1972-01-01

    The continuation of a paper discussing chemical bonding from a bond energy viewpoint, with a number of examples of single and multiple bonds. (Part I appeared in volume 1 number 3, pages 16-23, February 1972.) (AL)

  10. What Determines Bond Costs. Municipal Bonds Series.

    Science.gov (United States)

    Young, Douglas; And Others

    Public officials in small towns who participate infrequently in the bond market need information about bond financing. This publication, one in a series of booklets published by the Western Rural Development Center using research gathered between 1967-77, discusses factors influencing the marketability and cost of bond financing for towns and…

  11. Effect of simplified ethanol-wet bonding on microtensile bond strengths of dentin adhesive agents with different solvents

    Directory of Open Access Journals (Sweden)

    Muhammet Kerim Ayar

    2015-09-01

    Conclusion: Simplified ethanol-wet bonding exhibited similar 24-hour bond strength mean values for both ethanol/water-based and acetone-based etch-and-rinse adhesives. Therefore, solvent content may not interfere with bond strength to ethanol-saturated dentin.

  12. Against the Odds Exhibition Opens

    Science.gov (United States)

    ... Issue Past Issues Special Section Against the Odds Exhibition Opens Past Issues / Spring 2008 Table of Contents / ... April 17, Dr. Donald Lindberg officially opened the exhibition, "Against the Odds: Making a Difference in Global ...

  13. Exhibition

    CERN Multimedia

    Staff Association

    2014-01-01

    Energie sombre, matière noire J.-J. Dalmais - J. Maréchal Du 11 au 27 novembre 2014, CERN Meyrin, Bâtiment principal A l’image des particules atomiques qui ont tissé des liens pour créer la matière, deux artistes haut bugistes croisent leurs regards et conjuguent leurs expressions singulières pour faire naître une vision commune de l’univers, produit des forces primordiales. Les sculptures de Jean-Jacques Dalmais et les peintures de Jacki Maréchal se rencontrent pour la première fois et se racontent par un enrichissement mutuel la belle histoire de la Vie. Dialogue magique des œuvres en mouvement qui questionnent en écho l’énergie sombre et la matière noire. Cette harmonieuse confluence de jeux de miroir et de résonnance illumine de poésie et de sobriété l’espace expos&...

  14. Exhibition

    CERN Multimedia

    Staff Association

    2016-01-01

    The Elementary Particles of Painting Alfonso Fratteggiani Bianchi and Ermanno Imbergamo From September 26 to October 7, 2016 CERN Meyrin, Main Building With intentions similar to those of CERN physicists, the artist Alfonso Fratteggiani Bianchi investigates the color pigment, studying its interaction with light and with the support on which it is deposited. He creates monochrome paintings by spreading the color pigment in the pure state on stones, without using glue or any other type of adhesive. With intentions similar to artists, the physicist Ermanno Imbergamo investigates the use of luminescent wavelength shifters, materials commonly used in Particle Physics, for art. He creates other monochrome artworks, which disclose further aspects of interaction among light, color pigments and support. For more information: staff.association@cern.ch | Tel: 022 767 28 19

  15. Exhibition

    CERN Document Server

    Staff Association

    2018-01-01

    Cosmos KOLI Du 15 au 26 janvier 2018 CERN Meyrin, Main Building (Nébuleuse d'Orion- KOLI) KOLI, Artiste confirmé, diplômé de l’Académie de Beaux Arts de Tirana, depuis 26 ans en Suisse, où il a participé à maintes expositions collectives et organisé 10 expositions privées avec  beaucoup de succès, s’exprime actuellement dans un bonheur de couleur et de matières qui côtoient des hautes sphères… le cosmos ! Gagnant d’un premier prix lors d’une exposition collective organisée par le consulat Italien, il s’est installé au bord du lac dans le canton de Vaud où il vit depuis maintenant déjà 13 ans. www.kolicreation.com Pour plus d’informations et demandes d’accès : staff.association@cern.ch | T&eacut...

  16. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    La couleur des jours oriSio Du 2 au 12 mai 2017 CERN Meyrin, Bâtiment principal oriSio - Motus Suite à un fort intérêt pour la Chine et une curiosité pour un médium très ancien, la laque ! Je réinterprète cet art à travers un style abstrait. Je présente ici des laques sur aluminium, travaillés au plasma et ensuite colorés à l’aide de pigments pour l’essentiel. Mes œuvres je les veux brutes, déchirées, évanescentes, gondolées, voire trouées mais avec une belle approche de profondeur de la couleur.   Pour plus d’informations : staff.association@cern.ch | Tél: 022 766 37 38

  17. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Still Life Jérémy Bajulaz Du 25 septembre au 6 octobre 2017 CERN Meyrin, Main Building (Aubergine - Jérémy Bajulaz) Né en 1991 en Haute-Savoie, France. Diplômé de l'Ecole Emile Cohl à Lyon, Jérémy Bajulaz intègre en 2014 le programme d'artiste en résidence au Centre Genevois de Gravure Contemporaine. C'est là que son travail prendra corps, autour de la lumière et de ses vibrations aux travers de sujets comme le portrait et la nature morte, dans le souci de l'observation; le regard prenant une place importante dans le processus créatif. Lauréat 2017 du VII Premio AAAC, son travail a été présenté dans de nombreuses expositions collectives, en 2015 au Bâtiment d’Art Contemporain de Genève, en 2016 au 89e Salon de Lyon et du ...

  18. Exhibition

    CERN Multimedia

    Staff Association

    2016-01-01

    La mosaïque ou quand détruire permet de construire Lauren Decamps Du 28 novembre au 9 décembre 2016 CERN Meyrin, Bâtiment principal Paysage d'Amsterdam - Lauren Decamps On ne doit jamais rien détruire qu'on ne soit sûr de pouvoir remplacer aussi avantageusement " écrivait Plutarque dans ses Œuvres morales du 1er siècle après JC. L'artiste mosaïste Lauren Decamps adhère à cette idée et tente à sa manière de donner une nouvelle vie à ses matériaux en les taillant puis les réassemblant, créant ainsi des œuvres abstraites et figuratives.

  19. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Firmament des toiles Joëlle Lalagüe Du 6 au 16 juin 2017 CERN Meyrin, Bâtiment principal Phylaë Voyage - Joëlle Lalagüe. Each picture is an invitation for a cosmic trip. This is a whispering of soul, which comes from origins. A symphony of the world, some notes of love, a harmony for us to fly to infinity. Pour plus d’informations et demandes d'accès : staff.association@cern.ch | Tél: 022 766 37 38

  20. Exhibition

    CERN Multimedia

    Staff Association

    2016-01-01

    COLORATION Sandra Duchêne From September 5 to 16, 2016 CERN Meyrin, Main Building La recherche de l’Universel. Après tout ! C’est de l’Amour ! What else to say ? …La couleur, l’ENERGIE de la vie…

  1. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Le Point Isabelle Gailland Du 20 février au 3 mars 2017 CERN Meyrin, Bâtiment principal La Diagonale - Isabelle Gailland. Au départ, un toujours même point minuscule posé au centre de ce que la toile est un espace. Une réplique d'autres points, condensés, alignés, isolés, disséminés construiront dans leur extension, la ligne. Ces lignes, croisées, courbées, déviées, prolongées, seront la structure contenant et séparant la matière des couleurs. La rotation de chaque toile en cours d'exécution va offrir un accès illimité à la non-forme et à la forme. Le point final sera l'ouverture sur différents points de vue de ce que le point et la ligne sont devenus une représentation pour l'œil et l'im...

  2. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Harmonie Nathalie Lenoir Du 4 au 15 septembre 2017 CERN Meyrin, Bâtiment principal Peindre est un langage. Le tracé du pinceau sur le lin en est l'expression. A qui appartient un tableau en définitive ? A celui qui l'a peint ? A celui qui le regarde ? A celui qui l'emporte ? La peinture est une émotion partagée... Laissez-vous projeter de l'autre côté de la toile, prenez un moment pour rêver, en harmonie avec les éléments, parce-que la peinture parle à votre âme… Pour plus d’informations et demandes d’accès : staff.association@cern.ch | Tél : 022 766 37 38

  3. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Œuvres recentes Fabienne Wyler Du 6 au 17 février 2017 CERN Meyrin, Bâtiment principal L'escalier du diable B - aquarelle, encre de Chine XLV - Fabienne Wyler. En relation avec certains procédés d’écriture contemporaine (par ex. Webern ou certaines musiques conçues par ordinateur), les compositions picturales de Fabienne Wyler s’élaborent à partir de « modules » (groupes de quadrangles) qu’elle reproduit en leur faisant subir toutes sortes de transformations et de déplacements : étirements, renversements, rotations, effet miroir, transpositions, déphasages, superpositions, etc., et ceci à toutes les échelles. Au fil des œuvres sont apparues des séries intitulées, Bifurcations, Intermittences, Attracteurs étranges, Polyrythmies. Ces titres ont un lien &e...

  4. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Gaïa Manuella Cany Du 10 au 28 avril 2017 CERN Meyrin, Bâtiment principal Oiseau - Manuella Cany. Tableaux abstraits inspirés de vues satellites ou photos prises du ciel. Certains sont à la frontière du figuratif alors que d'autres permettent de laisser libre cours à son imagination. Aux détails infinis, ces tableaux sont faits pour être vus de loin et de près grâce à une attention toute particulière apportée aux effets de matières et aux couleurs le long de volutes tantôt nuancées tantôt contrastées.   Pour plus d’informations : staff.association@cern.ch | Tél: 022 766 37 38

  5. Exhibition

    CERN Multimedia

    Staff Association

    2014-01-01

      Parallels vision Astronomical subjects which evoke extrasensory kinetic visions Alberto Di Fabio From 8 to 10 October, CERN Meyrin, Main Building In the framework of Italy@cern, the Staff Association presents Alberto Di Fabio. Di Fabio’s work is inspired by the fundamental laws of the physical world, as well as organic elements and their interrelation. His paintings and works on paper merge the worlds of art and science, depicting natural forms and biological structures in vivid colour and imaginative detail. For all additional information: staff.association@cern.ch | Tel: 022 767 28 19

  6. Exhibition

    CERN Multimedia

    Staff Association

    2017-01-01

    Les vibrantes Patrick Robbe-Grillet Du 30 octobre au 10 novembre 2017 CERN Meyrin, Main Building Patrick Robbe-Grillet - Feux d'artifices Qui est Patrick Robbe-Grillet ? Artiste Franco-Suisse, né en 1968 à Genève. En recherche du sentiment de paix, autodidacte, après un séjour en Chine en 2000, puis au Japon en 2002, suivi d’un long questionnement, il trouve sa voie dans la peinture, élément libérateur de sa créativité et expression de sa sensibilité à fleur de peau. « La Chine m’a enseigné les courbes, les nuances. Le Japon, la ligne droite, la rigueur. » Vous avez su rendre visible l'invisible ! - commentaire de Monsieur Fawaz Gruosi Pour plus d’informations et demandes d’accès : staff.association@cern.ch | Tél : 022 766 37 38

  7. Exhibition

    CERN Multimedia

    Staff Association

    2011-01-01

    Jan Hladky, physicien de l'Institut de Physique de l'Académie des Sciences de la République tchèque, et membre de la collaboration Alice, expose ses œuvres au Bâtiment principal du 20 avril au 6 mai. Son exposition est dédiée aux victimes du séisme de Sendai. Des copies de ses œuvres seront mises en vente et les sommes récoltées seront versées au profit des victimes.

  8. Comparison of Shear Bond Strengths of three resin systems for a Base Metal Alloy bonded to

    Directory of Open Access Journals (Sweden)

    Jlali H

    1999-12-01

    Full Text Available Resin-bonded fixed partial dentures (F.P.D can be used for conservative treatment of partially edentulous"npatients. There are numerous studies regarding the strength of resin composite bond to base meta! alloys. Shear bond"nstrength of three resin systems were invistigated. In this study these systems consisted of: Panavia Ex, Mirage FLC and"nMarathon V. Thirty base metal specimens were prepared from rexillium III alloy and divided into three groups. Then each"ngroup was bonded to enamel of human extracted molar teeth with these systems. All of specimens were stored in water at"n37ac for 48 hours. A shear force was applied to each specimen by the instron universal testing machine. A statistical"nevaluation of the data using one-way analysis of variance showed that there was highly significant difference (P<0.01"nbetween the bond strengths of these three groups."nThe base metal specimens bonded with panavia Ex luting agent, exhibited the highest mean bond strength. Shear bond"nstrength of the specimens bonded to enamel with Mirage F1C showed lower bond strenght than panavia EX. However, the"nlowest bond strength was obtained by the specimens bonded with Marathon V.

  9. Rice-ball structures of iron-benzene clusters, Fe{sub 4}-(C{sub 6}H{sub 6}){sub m}, m Less-Than-Or-Slanted-Equal-To 3. A density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Valencia, Israel; Tavizon, Gustavo; Barba-Behrens, Norah [Departamento de Fisica y Quimica Teorica, DEPg. Facultad de Quimica, Universidad Nacional Autonoma de Mexico, C.P. 04510, Mexico D.F. (Mexico); Departamento de Quimica Inorganica, DEPg. Facultad de Quimica, Universidad Nacional Autonoma de Mexico, C.P. 04510, Mexico D.F. (Mexico); Castro, Miguel, E-mail: castro@quetzal.pquim.unam.mx [Departamento de Fisica y Quimica Teorica, DEPg. Facultad de Quimica, Universidad Nacional Autonoma de Mexico, C.P. 04510, Mexico D.F. (Mexico); Departamento de Quimica Inorganica, DEPg. Facultad de Quimica, Universidad Nacional Autonoma de Mexico, C.P. 04510, Mexico D.F. (Mexico)

    2011-11-18

    Graphical abstract: Adsorption of benzene molecules on Fe{sub 4} cluster. Highlights: Black-Right-Pointing-Pointer We studied the interactions of iron clusters with benzene molecules. Black-Right-Pointing-Pointer We have used density functional theory based methods for Fe{sub 4} and benzene. Black-Right-Pointing-Pointer The physicochemical properties were determined for the ground states. Black-Right-Pointing-Pointer The ground state structures for the Fe{sub 4}-benzene species were determined. - Abstract: Geometrical rice-ball structures of the Fe{sub 4} cluster with capped adsorbed benzene molecules for neutral, anion, and cation species, Fe{sub 4}-(C{sub 6}H{sub 6}){sub m} (m Less-Than-Or-Slanted-Equal-To 3), are studied by means of all-electron calculations done with the BPW91 approach of density functional theory jointly with 6-311++G(2d, 2p) basis sets. Electronic properties like ionization energies and electron affinities as well as binding energies are estimated and are in good agreement with recently reported experimental results. The computed IR spectra for these species show vibrational bands near those of the isolated benzene molecule and some forbidden IR modes of this ligand become IR active in Fe{sub 4}-(C{sub 6}H{sub 6}){sub m} (m Less-Than-Or-Slanted-Equal-To 3). The metal-benzene bonding issue was studied through the contour plots of molecular orbitals, showing signatures of metal-carbon bonding, originated from the 3d electrons of Fe{sub 4} and the 2p{pi} electrons of benzene.

  10. Wire bonding in microelectronics

    CERN Document Server

    Harman, George G

    2010-01-01

    Wire Bonding in Microelectronics, Third Edition, has been thoroughly revised to help you meet the challenges of today's small-scale and fine-pitch microelectronics. This authoritative guide covers every aspect of designing, manufacturing, and evaluating wire bonds engineered with cutting-edge techniques. In addition to gaining a full grasp of bonding technology, you'll learn how to create reliable bonds at exceedingly high yields, test wire bonds, solve common bonding problems, implement molecular cleaning methods, and much more. Coverage includes: Ultrasonic bonding systems and technologies, including high-frequency systems Bonding wire metallurgy and characteristics, including copper wire Wire bond testing Gold-aluminum intermetallic compounds and other interface reactions Gold and nickel-based bond pad plating materials and problems Cleaning to improve bondability and reliability Mechanical problems in wire bonding High-yield, fine-pitch, specialized-looping, soft-substrate, and extreme-temperature wire bo...

  11. Exhibition: Linus Pauling and the Twentieth Century

    CERN Multimedia

    2003-01-01

    On April 28 the exhibit Linus Pauling and the Twentieth Century organised by UNIDIR (United Nations Institute for Disarmament Research) and SGI (Soka Gakkai International) as well as with the contributions of CERN and the University of Geneva, opened at the United Nations Office of Geneva. Linus Pauling is the only person to date to have won two unshared Nobel Prizes: Chemistry in 1954 and Peace in 1962. The first was awarded for his landmark research on the nature of the chemical bond and its application in understanding the structure of complex substances. The second one acknowledged his courageous protest against atmospheric nuclear testing and his championship of international peace. The exhibit, for audience of all ages, traces seven decades of Linus Pauling's life and influence on the 20th century. Before starting its European tour at the UNESCO headquarters in Paris, the exhibit opened in 1998 in San Francisco and then travelled within the United-States and to Japan with an attendance of more than one...

  12. Exhibition: Linus Pauling and the Twentieth Century

    CERN Multimedia

    2003-01-01

    On April 28 the exhibit Linus Pauling and the Twentieth Century organised by UNIDIR (United Nations Institute for Disarmament Research) and SGI (Soka Gakkai International) as well as with the contributions of CERN and the University of Geneva, opens at the United Nations Office of Geneva. Linus Pauling is the only person to date to have won two unshared Nobel Prizes: Chemistry in 1954 and Peace in 1962. The first was awarded for his landmark research on the nature of the chemical bond and its application in understanding the structure of complex substances. The second one acknowledged his courageous protest against atmospheric nuclear testing and his championship of international peace. The exhibit, for all ages' audiences, traces seven decades of Linus Pauling's life and influence on the 20th century. Before starting its European tour at the UNESCO headquarters in Paris, the exhibit opened in 1998 in San Francisco and then travelled within the United-States and to Japan with an attendance of more than one m...

  13. Defying ageing: An expectation for dentine bonding with universal adhesives?

    Science.gov (United States)

    Zhang, Zheng-yi; Tian, Fu-cong; Niu, Li-na; Ochala, Kirsten; Chen, Chen; Fu, Bai-ping; Wang, Xiao-yan; Pashley, David H; Tay, Franklin R

    2016-02-01

    The present study evaluated the long-term dentine bonding effectiveness of five universal adhesives in etch-and-rinse or self-etch mode after 12 months of water-ageing. The adhesives evaluated included All-Bond Universal, Clearfil Universal Bond, Futurabond U Prime&Bond Elect and Scotchbond Universal. Microtensile bond strength and transmission electron microscopy of the resin-dentine interfaces created in human coronal dentine were examined after 24h or 12 months. Microtensile bond strength were significantly affected by bonding strategy (etch-and-rinse vs self-etch) and ageing (24h vs 12 months). All subgroups showed significantly decreased bond strength after ageing except for Prime&Bond Elect and Scotchbond Universal used in self-etch mode. All five adhesives employed in etch-and-rinse mode exhibited ultrastructural features characteristic of collagen degradation and resin hydrolysis. A previously-unobserved inside-out collagen degradation pattern was identified in hybrid layers created by 10-MDP containing adhesives (All-Bond Universal, Scotchbond Universal and Clearfil Universal Bond) in the etch-and-rinse mode, producing partially degraded collagen fibrils with intact periphery and a hollow core. In the self-etch mode, all adhesives except for Prime&Bond Elect exhibited degradation of the collagen fibrils along the thin hybrid layers. The three 10-MDP containing universal adhesives did not protect surface collagen fibrils from degradation when bonding was performed in the self-etch mode. Despite the adjunctive conclusion that bonds created by universal adhesives in the self-etch bonding mode are more resistant to decline in bond strength when compared with those bonds created using the etch-and-rinse mode, bonds created by universal adhesives are generally incapable of defying ageing. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. The World of Virtual Exhibitions

    Directory of Open Access Journals (Sweden)

    Irena Eiselt

    2013-09-01

    Full Text Available EXTENDED ABSTRACTSpecial collections of the National and University Library (NUK hide a lot of items of precious value. The Slovenian cultural heritage is stored on paper or on other media as a part of the library’s Manuscripts, Incunabula and Rare Books Collection, Old Prints Collection, Maps and Pictorial Collection, Music Collection, Ephemera Collection, Serials Collection, and Slovenian Diaspora Publications Collection. Only a small part of the treasures is temporary revealed to the public on special exhibitions. The idea of virtual exhibitions of library treasures was born in 2005. The library aimed to exhibit precious items of special collections of high historical or artistic value. In 2008 the first two virtual exhibitions were created in-house offering access to the rich collections of old postcards of Ljubljana at the beginning of 20th century kept in the Maps and Pictorial Collection of NUK. They were soon followed by other virtual exhibitions. At the beginning they were organised in the same way as physical exhibitions, afterwards different programs were used for creation of special effects (for ex. 3D wall. About two years ago it was decided that the creation of virtual exhibitions will be simplified. Files of digitised and borndigital library materials in jpg format are imported to MS PowerPoint 2010. Each jpg file is now formatted by adding a frame, a description … to the slides which are saved as jpg files. The last step is the import of jpg files into Cooliris application used for NUK web exhibitions. In the paper the virtual exhibition design and creation, the technical point of view and criteria for the selection of exhibition content are explained following the example of the virtual exhibitions the Old Postcards of Ljubljana, Photo Ateliers in Slovenia, a collection of photographs Four Seasons by Fran Krašovec and photos of Post-Earthquake Ljubljana in 1895.

  15. Exhibitions: Facing Outward, Pointing Inward

    Science.gov (United States)

    McDonald, Joseph P.

    2007-01-01

    The Coalition of Essential Schools (CES) Exhibitions Project of the early 1990s produced a range of work that continues to inform the practice of using exhibitions as a "360 degree" method of transforming teaching and learning, community connections, school design, and assessment. Among that work was this paper coupling the origins of exhibitions…

  16. The Pricing and Efficiency of Australian Treasury Bond Futures

    Directory of Open Access Journals (Sweden)

    Alex Frino

    2014-06-01

    Full Text Available This paper examines the efficiency of the Treasury Bond futures market in Australia. We provide a comprehensive explanation of the method used to price, and evaluate efficiency of the 3 and 10 Year Australian Treasury Bond Futures contracts, against underlying bond baskets. Results indicate that the futures contracts exhibit minimal variation from their theoretical value. The average mispricing equates to 1.96 basis points for 3 Year and 1.19 basis points for 10 Year government bond futures contracts. However, during some periods (including the financial crisis of 2008, the bond futures contracts exhibit greater mispricing. Consistent with prior literature, we find a decreasing pattern of mispricing towards expiry, with the futures contract yields and average forward yields of the underlying bonds converging towards expiry. Further analysis reveals that volatility and time to expiry exhibit a significant positive relationship with the absolute level of mispricing.

  17. A comparative study on the Mn/TiO2-M(M = Sn, Zr or Al) Ox catalysts for NH3-SCR reaction at low temperature.

    Science.gov (United States)

    Zhang, Yaping; Huang, Tianjiao; Xiao, Rui; Xu, Haitao; Shen, Kai; Zhou, Changcheng

    2017-05-29

    A series of TiO2-M(M = Sn, Zr or Al) Ox were prepared and manganese oxide (MnOx) was supported on the carrier by the traditional impregnation method for low-temperature selective catalytic reduction (SCR) of NOx with ammonia as a reductant. The obtained catalysts were characterized by XRD, BET, high-resolution transmission electron microscope (HRTEM), H2-TPR, NH3-TPD, X-ray photoelectron spectroscopy (XPS) and in situ Fourier-transform infrared (FT-IR) and their catalytic activities for NOx reduction with NH3 in the presence of SO2 were investigated comparatively. The results showed that the highest NOx conversion of over 90% could be obtained with the Mn/Ti-Sn catalyst at a wide range of temperature window of 150-270°C. The combination of characterization techniques, such as BET, XRD and HRTEM, revealed that manganese oxides were well dispersed on Ti-Sn. H2-TPR suggested that Ti-Sn and Ti-Zr supports could enhance the reduction ability of catalysts. Accordingly, Mn/Ti-Al exhibited worse activity at low temperature. XPS results were in good agreement with H2-TPR results, and Mn/Ti-Sn had more surface-reducible species of Mn4+ ions and more surface-adsorbed oxygen species, which was conducive to SCR reaction. The in situ FT-IR spectra of NH3 adsorption indicated that all the modified catalysts had more Lewis acid sites and the amide species at 1506 cm-1 had a certain influence on the catalytic reaction at low temperature. Mn/Ti-Zr showed a stronger resistance to SO2 but Mn/Ti-Al was affected more adversely and all the catalysts could not be restored to the initial catalytic activity after stopping feeding SO2. NH3-TPD revealed that the total acid amount of the Mn/Ti-Sn sample was larger than other samples, which indicated that the Ti-Sn solid solution could provide more surface acid sites over the catalyst.

  18. A new series of borophosphate phosphor Cd{sub 3}BPO{sub 7}:M (M = Ce{sup 3+}, Tb{sup 3+}, Mn{sup 2+}) with tunable luminescence and energy transfer properties

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiyu; Liu, Wei, E-mail: weiliu@ouc.edu.cn; Liu, Shuang; Cao, Lixin; Su, Ge; Gao, Rongjie; Jiang, Yu

    2016-04-25

    A new series of Cd{sub 3}BPO{sub 7}:M (M = Ce{sup 3+}, Tb{sup 3+}, Mn{sup 2+}) phosphors have been synthesized and characterized using X-ray powder diffraction as well as excitation and emission spectroscopy. Based on the Cd{sub 3}BPO{sub 7} host, the singly doping Ce{sup 3+}, Tb{sup 3+} and Mn{sup 2+} yield the blue, green and red-emitting phosphors respectively under the irradiation range from 270 to 300 nm UV. By appropriate tuning of Tb{sup 3+} or Mn{sup 2+} activator content, the emission color of the Cd{sub 3}BPO{sub 7}:Ce{sup 3+}/M (M = Tb{sup 3+} or Mn{sup 2+}) phosphors can be changed from blue to green or pink, respectively. Under UV excitation, the mixture of the as-prepared blue, green and red phosphors yields the warm white light, which exhibits their potential application as UV-convertible phosphors for WLEDs. - Highlights: • A new series of Cd{sub 3}BPO{sub 7}:M (M = Ce{sup 3+}, Tb{sup 3+}, Mn{sup 2+}) phosphors have been prepared. • The energy transfer from Ce{sup 3+} to Tb{sup 3+} is observed in Cd{sub 3}BPO{sub 7}:Ce{sup 3+}, Tb{sup 3+}. • Warm white light can be achieved by mixing physically the obtained tirphosphors.

  19. Photowalk Exhibition opens at Microcosm

    CERN Multimedia

    Katarina Anthony

    2011-01-01

    The winning photographs from the 2010 Global Particle Physics Photowalk competition will go on display at Microcosm from 11 February to 2 April. The exhibition is part of a global photography event taking place over three continents, with Photowalk exhibitions opening simultaneously at Fermilab in the US, KEK in Japan and here at CERN.   DESY wire chamber - First place people's choice; second place global jury competition. Photographer: Hans-Peter Hildebrandt  If you were one of the 1,300 photography lovers who voted in last year’s Photowalk competition, this exhibition is your chance to see the winning entries in print. The exhibition will take place in the downstairs gallery of Microcosm, overlooking the garden. 15 photographs will be on display, with each of the laboratories that participated in Photowalk represented by their 3 winning entries. Among them will be the “people’s choice” sunburst photo of a particle detector at DESY (Photo 1), and...

  20. Globe exhibit wins international acclaim

    CERN Multimedia

    Katarina Anthony

    2011-01-01

    The Globe’s “Universe of Particles” exhibition has recently received four prestigious awards for its avant-garde design. This external praise is great encouragement for the CERN exhibitions currently on the drawing board.   The Universe of Particles exhibition has won 4 awards for its avant-garde design. Back in 2008, the design company Atelier Brückner was presented with a challenge: to design the layout of a new permanent exhibition for CERN, one that would epitomize both the Organization and its research. The brief was concise but complex: the exhibit had to be symbolic of the Organization, use modern technology, engage and immerse visitors, and, preferably, use touch-screen technology. With the help of IArt, an interactive technology firm, and based on the content provided by CERN’s Education Group, Atelier Brückner developed the “Universe of Particles” exhibit as it is today. Its principal concept centred on the s...

  1. Halogen Bonds in Novel Polyhalogen Monoanions.

    Science.gov (United States)

    Wang, Changwei; Danovich, David; Shaik, Sason; Mo, Yirong

    2017-06-27

    Polyhalogen monoanions [X 2n+1 ] - (X=Cl and Br; n=1, 2, 3, 4, and 5) have been systematically studied using the block-localized wave function (BLW) method, which offers a valence bond (VB) analysis. For each species, the most stable isomer can be described as a central halide anion X - non-classically bonded to a number of dihalogen molecules X 2 via "halogen bonds". VB analyses confirm the dominant role of the charge-transfer interaction between the lone pair on X - and the σ-anti-bonding orbital of X 2 molecule (n→σ*) in X 3 - and higher analogues. Thus, our study demonstrates that these halogen bonds are essentially dative covalent interactions. Importantly, the charge-transfer interaction between [X 2n-1 ] - and X 2 decreases with the increasing n, in accord with the weakening of the Lewis basicity as characterized by the corresponding HOMO energy. The reduction of the charge transfer interaction underscores the reduction of covalence in halogen bonds in [X 2n+1 ] - . This tendency highlights the anti-cooperative effect in polyhalogen monoanions. All in all, the halogen bond between X - and nX 2 molecules exhibits the same trends as in X - with a single X 2 molecule. In other words, halogen bonding in the larger clusters derives from the same bonding mechanism as the [X 3 ] - anion. As such, the X - ⋅⋅⋅X 2 halogen bond at different bond lengths forms a gauge of covalence for the entire [X 2n+1 ] - family. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Acrylic mechanical bond tests

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, J.M.; Doe, P.J.

    1991-02-01

    The tensile strength of bonded acrylic is tested as a function of bond joint thickness. 0.125 in. thick bond joints were found to posses the maximum strength while the acceptable range of joints varied from 0.063 in. to almost 0.25 in. Such joints are used in the Sudbury Neutrino Observatory.

  3. Phenylacetylene and H bond

    Indian Academy of Sciences (India)

    ... all resembling H bonds. Non-linear H bonds due to secondary interactions. C-H stretching frequency shows blue shift. Heavy atom distances are longer than the sum of van der Waals radii. Formed a task group through IUPAC to come up with a modern definition of H bond. 15 international experts including Desiraju.

  4. Chemical bond fundamental aspects of chemical bonding

    CERN Document Server

    Frenking, Gernot

    2014-01-01

    This is the perfect complement to ""Chemical Bonding - Across the Periodic Table"" by the same editors, who are two of the top scientists working on this topic, each with extensive experience and important connections within the community. The resulting book is a unique overview of the different approaches used for describing a chemical bond, including molecular-orbital based, valence-bond based, ELF, AIM and density-functional based methods. It takes into account the many developments that have taken place in the field over the past few decades due to the rapid advances in quantum chemica

  5. A Note on Bayesian Estimation of the Traffic Intensity in M/M/1 Queue and Queue Characteristics under Quadratic Loss Function

    Directory of Open Access Journals (Sweden)

    Sanku Dey

    2009-01-01

    Full Text Available Bayes' estimators of the traffic intensity r and various queue characteristics in an M/M/1 queue have been derived under the assumptions of different priors for r and the quadratic error loss function (QELF. Finally, a numerical example is given to illustrate the results

  6. A Dynamic Supramolecular System Exhibiting Substrate Selectivity in the Catalytic Epoxidation of Olefins

    DEFF Research Database (Denmark)

    Jonsson, Stefan; Odille, Fabrice G. J.; Norrby, Per-Ola

    2005-01-01

    A dynamic supramolecular system involving hydrogen bonding between a Mn(III) salen catalyst and a Zn(II) porphyrin receptor exhibits selectivity for pyridine appended cis-beta-substituted styrene derivatives over phenyl appended derivatives in a catalytic epoxidation reaction.......A dynamic supramolecular system involving hydrogen bonding between a Mn(III) salen catalyst and a Zn(II) porphyrin receptor exhibits selectivity for pyridine appended cis-beta-substituted styrene derivatives over phenyl appended derivatives in a catalytic epoxidation reaction....

  7. Prospective bonding applications

    Science.gov (United States)

    Ancenay, H.; Benazet, D.

    1981-07-01

    Adhesive bonding in industry and in the laboratory is surveyed and prospects for its wider utilization are assessed. The economic impact of bonding technology on industry is discussed. Research is reviewed, centering on the development of nondestructive testing and inspection techniques. Traditional (wood) as well as new materials susceptible to bonding are considered. Applications in construction and civil engineering, in aeronautics, and in the automobile industry are covered. The use of glues in mechanical constructions, in assembling cylindrical parts, and in metal-metal bonding are examined. Hybrid assembling and bonding of composite materials are included.

  8. Exhibition - Mathematics, A Beautiful Elsewhere

    CERN Multimedia

    2011-01-01

    From 21 October 2011 to 18 March 2012, the Fondation Cartier pour l’art contemporain will present the exhibition Mathematics: A Beautiful Elsewhere, an exhibition developed in association with the Institut des Hautes Études Scientifiques (IHÉS) and under the patronage of UNESCO. For this unprecedented event, the foundation invited mathematicians to work with artists with whom it has previously worked to create an exhibition that allows visitors to see, hear, do, interpret and think about mathematics. By bringing mathematics into its premises, the Fondation Cartier is itself undergoing the “sudden change of scenery” described by mathematician Alexandre Grothendieck. More information is available here. Fondation Cartier pour l’art contemporain 261, boulevard Raspail 75014 Paris http://fondation.cartier.com Private Visit For professors, researchers and all the staff of Mathematics departments...

  9. Complexes between hypohalous acids and phosphine derivatives. Pnicogen bond versus halogen bond versus hydrogen bond.

    Science.gov (United States)

    Li, Qingzhong; Zhu, Hongjie; Zhuo, Hongying; Yang, Xin; Li, Wenzuo; Cheng, Jianbo

    2014-11-11

    The complexes of HOBr:PH2Y (Y=H, F, Cl, Br, CH3, NH2, OH, and NO2), HOCl:PH2F, and HOI:PH2F have been investigated with ab initio calculations at the MP2/aug-cc-pVTZ level. Four types of structures (1, 2, 3a, and 3b) were observed for these complexes. 1 is stabilized by an O⋯P pnicogen bond, 2 by a P⋯X halogen bond, 3a by a H⋯P hydrogen bond and a P⋯X pnicogen bond, and 3b by H⋯P and H⋯Br hydrogen bonds. Their relative stability is related to the halogen X of HOX and the substituent Y of PH2Y. These structures can compete with interaction energy of -10.22∼-29.40 kJ/mol. The HO stretch vibration shows a small red shift in 1, a small irregular shift in 2, but a prominent red shift in 3a and 3b. The XO stretch vibration exhibits a smaller red shift in 1, a larger red shift in 2, but an insignificant blue shift in 3a and 3b. The PY stretch vibration displays a red shift in 1 but a blue shift in 2, 3a, and 3b. The formation mechanism, stability, and properties of these structures have been analyzed with molecular electrostatic potentials, orbital interactions, and non-covalent interaction index. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Weak bond screening system

    Science.gov (United States)

    Chuang, S. Y.; Chang, F. H.; Bell, J. R.

    Consideration is given to the development of a weak bond screening system which is based on the utilization of a high power ultrasonic (HPU) technique. The instrumentation of the prototype bond strength screening system is described, and the adhesively bonded specimens used in the system developmental effort are detailed. Test results obtained from these specimens are presented in terms of bond strength and level of high power ultrasound irradiation. The following observations were made: (1) for Al/Al specimens, 2.6 sec of HPU irradiation will screen weak bond conditions due to improper preparation of bonding surfaces; (2) for composite/composite specimens, 2.0 sec of HPU irradiation will disrupt weak bonds due to under-cured conditions; (3) for Al honeycomb core with composite skin structure, 3.5 sec of HPU irradiation will disrupt weak bonds due to bad adhesive or oils contamination of bonding surfaces; and (4) for Nomex honeycomb with Al skin structure, 1.3 sec of HPU irradiation will disrupt weak bonds due to bad adhesive.

  11. Markov model M/M/m/K in contact center

    OpenAIRE

    Erik Chromy; Jan Diezka; Matej Kavacky

    2012-01-01

    Our paper deals with a contact center dimensioning. The main task of a contact center is to offer services to customers. The most simple and genuine way of communication with the contact center agent is by phone. From the customer satisfaction point of view, the shortest serving time is the most important factor. It is known that the highest operating costs of the contact center are costs for agents. Therefore, we need to choose the right number of agents and effectively utilize them. For con...

  12. Si-to-Si wafer bonding using evaporated glass

    DEFF Research Database (Denmark)

    Reus, Roger De; Lindahl, M.

    1997-01-01

    Anodic bonding of Si to Si four inch wafers using evaporated glass was performed in air at temperatures ranging from 300°C to 450°C. Although annealing of Si/glass structures around 340°C for 15 minutes eliminates stress, the bonded wafer pairs exhibit compressive stress. Pull testing revealed...

  13. Mobile Technologies in Museum Exhibitions

    Directory of Open Access Journals (Sweden)

    Sandra Medić

    2014-10-01

    Full Text Available In order to be up–to–date and give visitors a memorable and unique experience, museums are including usage of digital technologies in their exhibitions. Even though museums in Serbia are very important part of tourism offer, they still have traditional settings that are poorly interpreted. The majority of them have a scientific and historical review which is unattractive for various target groups of visitors and for museums it’s important to continually try out new ways in interpretation of their settings. Because technology continues to rapidly change the way we communicate, cultural institutions should adapt to new ways of communication with their visitors. This paper examines mobile technologies that can be used in museums to give visitors a different experience and transfer the knowledge innovatively. In that way it will be presented the modern concept of presentation of museum exhibitions, focusing on usage of mobile devices through mobile applications and QR codes. The paper provides the broad understanding of usage mobile technologies in museum exhibitions with its advantages and limitations. The research results can help the museums management to improve interpretation and communication with visitors and enrich the visitor experience.

  14. "Big Science" exhibition at Balexert

    CERN Multimedia

    2008-01-01

    CERN is going out to meet those members of the general public who were unable to attend the recent Open Day. The Laboratory will be taking its "Big Science" exhibition from the Globe of Science and Innovation to the Balexert shopping centre from 19 to 31 May 2008. The exhibition, which shows the LHC and its experiments through the eyes of a photographer, features around thirty spectacular photographs measuring 4.5 metres high and 2.5 metres wide. Welcomed and guided around the exhibition by CERN volunteers, shoppers at Balexert will also have the opportunity to discover LHC components on display and watch films. "Fun with Physics" workshops will be held at certain times of the day. Main hall of the Balexert shopping centre, ground floor, from 9.00 a.m. to 7.00 p.m. Monday to Friday and from 10 a.m. to 6 p.m. on the two Saturdays. Call for volunteers All members of the CERN personnel are invited to enrol as volunteers to help welcom...

  15. Silicon-to-silicon wafer bonding using evaporated glass

    DEFF Research Database (Denmark)

    Weichel, Steen; Reus, Roger De; Lindahl, M.

    1998-01-01

    Anodic bending of silicon to silicon 4-in. wafers using an electron-beam evaporated glass (Schott 8329) was performed successfully in air at temperatures ranging from 200 degrees C to 450 degrees C. The composition of the deposited glass is enriched in sodium as compared to the target material...... of silicon/glass structures in air around 340 degrees C for 15 min leads to stress-free structures. Bonded wafer pairs, however, show no reduction in stress and always exhibit compressive stress. The bond yield is larger than 95% for bonding temperatures around 350 degrees C and is above 80% for bonding...... from 25 N/mm(2) to 0 N/mm(2) at 200 degrees C. A weak dependence on feature size was observed. For bonding temperatures higher than 300 degrees C fracture occurs randomly in the bulk of the silicon, whereas for bonding temperatures lower than 300 degrees C fracture always occurs at the bonding...

  16. Chemical bonding technology

    Science.gov (United States)

    Plueddemann, E.

    1986-01-01

    Primers employed in bonding together the various material interfaces in a photovoltaic module are being developed. The approach develops interfacial adhesion by generating actual chemical bonds between the various materials bonded together. The current status of the program is described along with the progress toward developing two general purpose primers for ethylene vinyl acetate (EVA), one for glass and metals, and another for plastic films.

  17. Measles, mumps, and rubella virus vaccine (M-M-R™II): a review of 32 years of clinical and postmarketing experience.

    Science.gov (United States)

    Lievano, Fabio; Galea, Susan A; Thornton, Michele; Wiedmann, Richard T; Manoff, Susan B; Tran, Trung N; Amin, Manisha A; Seminack, Margaret M; Vagie, Kristen A; Dana, Adrian; Plotkin, Stanley A

    2012-11-06

    M-M-R™II (measles, mumps, and rubella virus vaccine live; Merck, Sharp, & Dohme Corp.) is indicated for simultaneous vaccination against measles, mumps, and rubella in individuals ≥ 12 months of age. Before the vaccine era, these viruses infected most exposed individuals, with subsequent morbidity and mortality. One of the greatest achievements of public health has been to eliminate these 3 diseases in large geographic areas. The safety profile of M-M-R™II is described using data from routine global postmarketing surveillance. Postmarketing surveillance has limitations (including incomplete reporting of case data), but allows collection of real-world information on large numbers of individuals, who may have concurrent medical problems excluding them from clinical trials. It can also identify rare adverse experiences (AEs). Over its 32-year history, ≈ 575 million doses of M-M-R™II have been distributed worldwide, with 17,536 AEs voluntarily reported for an overall rate of 30.5 AEs/1,000,000 doses distributed. This review provides evidence that the vaccine is safe and well-tolerated. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  19. Borneo 2007. Three European Exhibitions

    OpenAIRE

    Bernard Sellato

    2013-01-01

    The year 2007 appears to have been an exceptionally good one for Borneo in Europe. Two exhibitions were held in France, and one in Switzerland, which prominently featured the big island, its forests, its peoples, its cultures, and its arts. Here a brief review of these three events. Bornéo... Dayak et Punan. Peuples de la forêt tropicale humide, Musée d’Art et d’Archéologie, Laon, France, 25 November 2006 – 11 March 2007 The beautiful city of Laon, only a short distance by train or by car fro...

  20. Borneo 2007. Three European Exhibitions

    Directory of Open Access Journals (Sweden)

    Bernard Sellato

    2013-01-01

    Full Text Available The year 2007 appears to have been an exceptionally good one for Borneo in Europe. Two exhibitions were held in France, and one in Switzerland, which prominently featured the big island, its forests, its peoples, its cultures, and its arts. Here a brief review of these three events. Bornéo... Dayak et Punan. Peuples de la forêt tropicale humide, Musée d’Art et d’Archéologie, Laon, France, 25 November 2006 – 11 March 2007 The beautiful city of Laon, only a short distance by train or by car fro...

  1. CERN Permanent exhibitions short version

    CERN Multimedia

    2016-01-01

    Visits Explore by yourself the issues CERN's physicists are trying to solve: given that the entire universe is made of particles, where do they come from? Why do they behave in the way they do? Discover the massive apparatus used by physicists at CERN, like the LHC, and see how each part works. CERN invites the public to discover the mysteries of the Universe and the work of the world's biggest physics laboratory through free of charge guided tours and permanent exhibitions. As a group, with friends, individually, on foot, on your bike, come and discover CERN or explore it virtually. Welcome!

  2. Ethanol-wet bonding technique may enhance the bonding performance of contemporary etch-and-rinse dental adhesives.

    Science.gov (United States)

    Li, Fang; Liu, Xiao-Yang; Zhang, Ling; Kang, Jun-Jun; Chen, Ji-Hua

    2012-04-01

    To determine whether bonds of contemporary etch-and-rinse adhesives made with ethanol-wet bonding are stronger and more durable than those made with water-wet bonding, and to explore the possible reasons for the bonding results. Flat surfaces of midcoronal dentin were made in extracted human third molars. The dentin surfaces were randomized into 6 groups according to bonding techniques (water- vs ethanol-wet bonding) and dental adhesives [Single Bond 2 (SB), Prime Bond NT (PB), and Gluma Comfort Bond (GB)]. After etching and rinsing, dentin surfaces were either left water-moist or immersed in ethanol. Following adhesive application and composite buildups, the bonded teeth were sectioned into beams for microtensile bond strength evaluation with or without NaOCl challenge. The morphology of the hybrid layer was analyzed with SEM. The wettability of water- vs. ethanol-saturated dentin was evaluated. The concentrations of non-volatile ingredients in the adhesives were compared. Compared to water-wet bonding, ethanol-wet bonding yielded similar (p > 0.05 for PB and GB) or higher (p adhesives), and produced more even hybrid layers. Moreover, ethanol-saturated dentin exhibited a lower contact angle than water-saturated specimens, and the concentrations of non-volatile ingredients of the adhesives decreased in the order of SB > GB > PB. Ethanol-wet bonding could improve the bonding efficacy of contemporary etch-and-rinse adhesives, probably due to the good wettability of ethanol-saturated dentin and the structure of the hybrid layer. Moreover, this positive effect of ethanol-wet bonding might be influenced by the composition of adhesives.

  3. 27 CFR 24.147 - Operations bond or unit bond.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Operations bond or unit... § 24.147 Operations bond or unit bond. Notwithstanding the provisions of § 24.146, each person... amended, give an operations bond or unit bond in accordance with the applicable provisions of 27 CFR part...

  4. Comparison of Gold Bonding with Mercury Bonding

    NARCIS (Netherlands)

    Kraka, Elfi; Filatov, Michael; Cremer, Dieter

    2009-01-01

    Nine AuX molecules (X = H, O, S, Se, Te, F, Cl, Br, I), their isoelectronic HgX(+) analogues, and the corresponding neutral HgX diatomics have been investigated using NESC (Normalized Elimination of the Small Component) and B3LYP theory to determine relativistic effects for bond dissociation

  5. Mother-Child Bonding.

    Science.gov (United States)

    Pearce, Joseph Chilton

    1994-01-01

    Examines the nature of mother-child bonding from the prenatal stage through early infancy, discussing how the mother's actions, even before birth, stimulate her child's senses. Explains the crucial role that physical contact, breastfeeding, and visual stimuli have on mother-child bonding in human and animal newborns. (MDM)

  6. Chemical Bonds I

    Science.gov (United States)

    Sanderson, R. T.

    1972-01-01

    Chemical bonding is discussed from a bond energy, rather than a wave mechanics, viewpoint. This approach is considered to be more suitable for the average student. (The second part of the article will appear in a later issue of the journal.) (AL)

  7. Corporate Bonds in Denmark

    DEFF Research Database (Denmark)

    Tell, Michael

    2015-01-01

    to think in alternative ways such as issuing corporate bonds. A market for corporate bonds exists in countries such as Norway, Germany, France, the United Kingdom and the United States, while Denmark is still behind in this trend. Some large Danish corporations have instead used foreign corporate bonds...... markets. However, NASDAQ OMX has introduced the First North Bond Market in December 2012 and new regulatory framework came into place in 2014, which may contribute to a Danish based corporate bond market. The purpose of this article is to present the regulatory changes in Denmark in relation to corporate......Corporate financing is the choice between capital generated by the corporation and capital from external investors. However, since the financial crisis shook the markets in 2007–2008, financing opportunities through the classical means of financing have decreased. As a result, corporations have...

  8. Water's Hydrogen Bond Strength

    CERN Document Server

    Chaplin, Martin

    2007-01-01

    Water is necessary both for the evolution of life and its continuance. It possesses particular properties that cannot be found in other materials and that are required for life-giving processes. These properties are brought about by the hydrogen bonded environment particularly evident in liquid water. Each liquid water molecule is involved in about four hydrogen bonds with strengths considerably less than covalent bonds but considerably greater than the natural thermal energy. These hydrogen bonds are roughly tetrahedrally arranged such that when strongly formed the local clustering expands, decreasing the density. Such low density structuring naturally occurs at low and supercooled temperatures and gives rise to many physical and chemical properties that evidence the particular uniqueness of liquid water. If aqueous hydrogen bonds were actually somewhat stronger then water would behave similar to a glass, whereas if they were weaker then water would be a gas and only exist as a liquid at sub-zero temperature...

  9. Bonding of primed zirconia ceramics: evidence of chemical bonding and improved bond strengths.

    Science.gov (United States)

    Chen, Liang; Suh, Byoung In; Brown, Douglas; Chen, Xinqi

    2012-04-01

    To investigate changes of zirconia surface hydrophobicity (contact angle) following the application of a zirconia primer as a function of post-priming storage period and after exposure to harsh conditions and to analyze whether there is a chemical bond formation between a zirconia primer and zirconia ceramics. Zirconia ceramics were treated with a zirconia primer (ZPrime Plus, Bisco), left undisturbed for specific times (reaction time), followed by ultrasonic cleansing in ethanol or acetone bath, and then contact angles were measured (n = 10). The primed zirconia ceramics were also subjected to harsh conditions (strong acid or boiling water) prior to contact angle testing. The chemical change of zirconia surface with and without being primed was analyzed by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Shear bond strength (Ultradent jig method) on zirconia surface was tested using different zirconia primers. The data were statistically analyzed using one-way ANOVA and Tukey's post-hoc test with 95% confidence level. The contact angle on the primed zirconia surface (from 56 degrees to 72 degrees for different primers) was significantly higher than that of unprimed zirconia (15 degrees) (P reaction time increased within 5 minutes (increased from 58 degree at 10 seconds, to 72 degrees at 5 minutes). Exposure to harsh conditions (i.e. strong acid or boiling water) exhibited no significant change in contact angle values (P > 0.05). The TOF-SIMS detected fragmentations with mass of 549 and 411, indicating that a chemical group of phosphate monomer(P)-O-Zr existed, which indicated a chemical bond was formed between zirconia and ZPrime Plus. All of the zirconia primers tested in the study significantly improved zirconia bond strengths (4 MPa for unprimed zirconia, and 17-23 MPa for primed zirconia, P < 0.05).

  10. Effect of moist bonding on composite/enamel bond strength.

    Science.gov (United States)

    Moll, Karlheinz; Gärtner, Thomas; Haller, Bernd

    2002-04-01

    To evaluate the effect of moist bonding on shear bond strength of resin-based composite to enamel using different adhesive systems. Six restorative systems were selected for this study: OptiBond FL/Prodigy, Solid Bond/Charisma F, Syntac Single Component/Tetric, Prime&Bond 2.1/Spectrum TPH, Single Bond/Z100, Etch&Prime 3.0/Degufill Mineral. Flat enamel surfaces were ground on the buccal and lingual aspects of 80 extracted human molars. OptiBond FL and Solid Bond were tested with and without primer application. Prior to application of the adhesives, the enamel was either carefully dried with compressed air (dry bonding) or blot dried with a cotton pellet (moist bonding). Shear bond strength was determined with a universal testing machine after 24-hour storage in 0.9% NaCl at 37 degrees C. Moist bonding did not significantly affect shear bond strength to enamel of the adhesives tested except for Solid Bond without primer application. Primer contamination of the etched enamel did not significantly influence bond strength, neither in the dry bonding nor in the moist bonding group. Of all adhesives tested in both groups, the highest mean bond strength was observed with Prime&Bond 2.1 and the lowest with Etch&Prime 3.0.

  11. Enrico Fermi exhibition at CERN

    CERN Multimedia

    2002-01-01

    A touring exhibition celebrating the centenary of Enrico Fermi's birth in 1901 will be on display at CERN (Main Building, Mezzanine) from 12-27 September. You are cordially invited to the opening celebration on Thursday 12 September at 16:00 (Main Building, Council Chamber), which will include speechs from: Luciano Maiani Welcome and Introduction Arnaldo Stefanini Celebrating Fermi's Centenary in Documents and Pictures Antonino Zichichi The New 'Centro Enrico Fermi' at Via Panisperna Ugo Amaldi Fermi at Via Panisperna and the birth of Nuclear Medicine Jack Steinberger Fermi in Chicago Valentin Telegdi A Close-up of Fermi and the screening of a documentary video about Fermi: Scienziati a Pisa: Enrico Fermi (Scientists at Pisa: Enrico Fermi) created by Francesco Andreotti for La Limonaia from early film, photographs and sound recordings (In Italian, with English subtitles - c. 30 mins). This will be followed by an aperitif on the Mezz...

  12. Crows spontaneously exhibit analogical reasoning.

    Science.gov (United States)

    Smirnova, Anna; Zorina, Zoya; Obozova, Tanya; Wasserman, Edward

    2015-01-19

    Analogical reasoning is vital to advanced cognition and behavioral adaptation. Many theorists deem analogical thinking to be uniquely human and to be foundational to categorization, creative problem solving, and scientific discovery. Comparative psychologists have long been interested in the species generality of analogical reasoning, but they initially found it difficult to obtain empirical support for such thinking in nonhuman animals (for pioneering efforts, see [2, 3]). Researchers have since mustered considerable evidence and argument that relational matching-to-sample (RMTS) effectively captures the essence of analogy, in which the relevant logical arguments are presented visually. In RMTS, choice of test pair BB would be correct if the sample pair were AA, whereas choice of test pair EF would be correct if the sample pair were CD. Critically, no items in the correct test pair physically match items in the sample pair, thus demanding that only relational sameness or differentness is available to support accurate choice responding. Initial evidence suggested that only humans and apes can successfully learn RMTS with pairs of sample and test items; however, monkeys have subsequently done so. Here, we report that crows too exhibit relational matching behavior. Even more importantly, crows spontaneously display relational responding without ever having been trained on RMTS; they had only been trained on identity matching-to-sample (IMTS). Such robust and uninstructed relational matching behavior represents the most convincing evidence yet of analogical reasoning in a nonprimate species, as apes alone have spontaneously exhibited RMTS behavior after only IMTS training. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Halogen-bonding-triggered supramolecular gel formation

    Science.gov (United States)

    Meazza, Lorenzo; Foster, Jonathan A.; Fucke, Katharina; Metrangolo, Pierangelo; Resnati, Giuseppe; Steed, Jonathan W.

    2013-01-01

    Supramolecular gels are topical soft materials involving the reversible formation of fibrous aggregates using non-covalent interactions. There is significant interest in controlling the properties of such materials by the formation of multicomponent systems, which exhibit non-additive properties emerging from interaction of the components. The use of hydrogen bonding to assemble supramolecular gels in organic solvents is well established. In contrast, the use of halogen bonding to trigger supramolecular gel formation in a two-component gel (‘co-gel’) is essentially unexplored, and forms the basis for this study. Here, we show that halogen bonding between a pyridyl substituent in a bis(pyridyl urea) and 1,4-diiodotetrafluorobenzene brings about gelation, even in polar media such as aqueous methanol and aqueous dimethylsulfoxide. This demonstrates that halogen bonding is sufficiently strong to interfere with competing gel-inhibitory interactions and create a ‘tipping point’ in gel assembly. Using this concept, we have prepared a halogen bond donor bis(urea) gelator that forms co-gels with halogen bond acceptors.

  14. Are One-Electron Bonds Any Different from Standard Two-Electron Covalent Bonds?

    Science.gov (United States)

    Sousa, David Wilian Oliveira de; Nascimento, Marco Antonio Chaer

    2017-09-19

    molecules H 2 + , H 3 C·CH 3 + , B 2 H 4 - , [Cu·BH 3 (PH 3 ) 3 ], and an alkali-metal cation dimer, and we evaluated the components of the electronic energy and density, which account for the formation of the bond, and compared the results with those for the respective analogous molecules exhibiting the "conventional" two-electron bond. In all cases, it was verified that interference is the dominant effect for the one-electron bonds. The GPF-EP results clearly indicate that molecules exhibiting (2c1e) bonds should not be considered as special systems, since one- and two-electron bonds result from quantum interference and therefore there is no conceptual difference between them. Moreover, these results show that quantum interference provides a way to unify the chemical bond concept.

  15. DNA synthesis and microtubule assembly-related events in fertilized Paracentrotus lividus eggs: reversible inhibition by 10 mM procaine.

    Science.gov (United States)

    Raymond, M N; Foucault, G; Coffe, G; Pudles, J

    1986-04-01

    This report describes the effects of 10 mM procaine on microtubule assembly and on DNA synthesis, as followed by [3H]colchicine binding assays and [3H]thymidine incorporation respectively, in fertilized Paracentrotus lividus eggs. In the absence of microtubule assembly inhibitors, about 25% of the total egg tubulin is submitted to two cycles of polymerization prior to the first cell division, this polymerization process precedes DNA synthesis. If the zygotes are treated with 10 mM procaine in the course of the cell cycle, tubulin polymerization is inhibited or microtubules are disassembled. DNA synthesis is inhibited when procaine treatment is performed 10 min, before the initiation of the S-period. However, when the drug is applied in the course of this synthetic period, the process is normally accomplished, but the next S-period becomes inhibited. Moreover, procaine treatment increases the cytoplasmic pH of the fertilized eggs by about 0.6 to 0.8 pH units. This pH increase precedes microtubule disassembly and inhibition of DNA synthesis. Washing out the drug induces a decrease of the intracellular pH which returns to about the same value as that of the fertilized egg controls. This pH change is then followed by the reinitiation of microtubule assembly, DNA synthesis and cell division. Our results show that the inhibition of both tubulin polymerization and DNA synthesis in fertilized eggs treated with 10 mM procaine, appears to be related to the drug-induced increase in cytoplasmic pH.

  16. The effect of repeated fluoride recharge and storage media on bond durability of fluoride rechargeable Giomer bonding agent.

    Science.gov (United States)

    Naoum, S; O'Regan, J; Ellakwa, A; Benkhart, R; Swain, M; Martin, E

    2012-06-01

    For a restorative material or adhesive to exhibit caries inhibitive potential through fluoride release, it must be capable of fluoride recharge. The aim of this study was to evaluate the effect of repeated fluoride recharge and different storage media on dentine bond strength durability. Two self-etch adhesive systems (two-step) were evaluated: fluoride-rechargeable Giomer FL-Bond II and non-fluoride-containing UniFil Bond. For each adhesive 32 human dentine specimens were prepared for shear bond strength testing. The specimens were randomly allocated to one of four storage groups: Group 1 - 24-hour water ageing; Group 2 - four-month water ageing; Group 3 - four-month water ageing with weekly fluoride recharge (5000 ppm for 10 minutes); and Group 4 - four-month acid ageing with weekly fluoride recharge. Weekly fluoride recharge over four months ageing did not significantly (p > 0.05) reduce the dentine shear bond strength of FL-Bond II or UniFil Bond. Storage media did not significantly (p > 0.05) affect bond durability. The adhesion between fluoride rechargeable FL-Bond II and dentine maintained durability despite regular fluoride recharge over the four months ageing. Clinicians prescribing the fluoride recharge regime used in the present study to reduce recurrent caries incidence associated with Giomer FL-Bond II restorations can do so without compromising dentine bond strengths. © 2012 Australian Dental Association.

  17. All-Russian conference on legal and forensic psychology dedicated to the memory of M.M. Kochenov-2016 in MSUPE

    Directory of Open Access Journals (Sweden)

    Dozortseva E.G.

    2017-01-01

    Full Text Available In November 2016 the traditional All-Russian conference on legal and forensic psychology dedicated to the memory of the prominent Russian psychologist M.M. Kochenov took place. In the article a brief description of the history of the biennial conference is given, as well as problems of the current scientific event under the title “Psychology and Law in the modern Russia”, which united Russian and foreign specialists. A range of topics of the articles presented at the conference and being published in the current journal issue is introduced.

  18. A note on the convexity of the expected queue length of the M/M/s queue with respect to the arrival rate: a third proof

    Directory of Open Access Journals (Sweden)

    A. Mehrez

    1992-01-01

    Full Text Available The convexity of the expected number in an M/M/s queue with respect to the arrival rate (or traffic intensity is well known. Grassmann [1] proves this result directly by making use of a bound on the probability that all servers are busy. Independently, Lee and Cohen [2] derive this result by showing that the Erlang delay formula is a convex function. In this note, we provide a third method of proof, which exploits the relationship between the Erlang delay formula and the Poisson probability distribution. Several interesting intermediate results are also obtained.

  19. Impact of reductive cleavage of an intramolecular disulfide bond containing cationic gemini surfactant in monolayers and bilayers.

    Science.gov (United States)

    Säily, V Matti J; Ryhänen, Samppa J; Lankinen, Hilkka; Luciani, Paola; Mancini, Giovanna; Parry, Mikko J; Kinnunen, Paavo K J

    2006-01-31

    The properties of a novel disulfide-bond-containing gemini surfactant bis[N,N-dimethyl-N-hexadecyl-N-(2-mercaptoethyl)ammonium bromide] disulfide (DSP) were studied using a Langmuir balance, supported monolayers, differential scanning calorimetry, giant vesicles, and LUVs. In 150 mM NaCl the cmc for DSP was 7.5 microM whereas that of the monomer N,N-dimethyl-N-hexadecyl-N-(2-mercaptoethyl)ammonium bromide (MSP) was 12.1 microM. Both surfactants exhibited single endotherms upon DSC, with peak temperatures Tm at 21.7 and 20.1 degrees C for DSP and MSP, respectively. The endotherm for MSP was significantly broader indicating less cooperative melting. Both in monolayers and in vesicles reductive cleavage of the disulfide bond of DSP could be obtained by glutathione (GSH). For Langmuir films of DSP the addition of GSH into the subphase led to a decrease in surface pressure pi as well as surface dipole potential psi. Although the cleavage by GSH was significantly slower in the presence of a charge saturating concentration of DNA, it did not prevent the reaction. The resulting monomers detached from supported monolayers, leading to loss of affinity of the surface for DNA. Disruption of giant vesicles containing DSP within approximately 30 s following a local injection of GSH was observed, revealing membrane destabilization.

  20. Initial and fatigue bond strengths of nanofilled and conventional composite bonding adhesives.

    Science.gov (United States)

    BenGassem, Afnan A; Georgiou, George; Jones, Steven Peter

    2013-06-01

    To compare the initial and fatigue shear bond strengths of a nanofilled adhesive with a conventional light-cured adhesive in an ex vivo laboratory study. Fifty hydroxyapatite discs were prepared by cold pressing. Using a standardized bonding protocol, 100 Victory series upper left central incisor brackets were bonded to discs with Transbond™ Supreme LV nanofilled composite resin and 100 brackets were bonded to discs with Transbond XT. Fifty brackets from each group were subjected to cyclic loading (5000 cycles at 2 Hz) at 50% of the mean bond strength in a Dartec Series HC10 Testing Machine. Initial (unfatigued) and fatigued bond strengths were determined by applying a shear force at the bracket/substrate interface using a custom-made metal jig in an Instron Universal Testing Machine. RESULTS AND STATISTICAL ANALYSIS: One-way analysis of variance showed that Transbond Supreme LV exhibited higher initial mean bond strength than Transbond XT (P = 0·001). No statistically significant difference was found between the fatigue bond strengths of Transbond Supreme LV and Transbond XT (P = 0·323). Two-way analysis of variance demonstrated statistically significant differences when the effect of the composite resin (P = 0·013) and fatigue (P = 0·017) were considered individually. However, when considered in combination there was no statistical significance (P = 0·09). Kaplan-Meier survival analysis showed superior survival of unfatigued brackets with Transbond Supreme LV, but there was no significant difference between the adhesives after fatiguing. The initial bond strength of Transbond Supreme LV was significantly higher than Transbond XT, while the fatigue bond strengths of both resins were comparable. Overall, Transbond Supreme LV demonstrated superior survival under loading than Transbond XT. However, while this was statistically significant for the initial loading, it was not significant after fatiguing. Although these laboratory findings are

  1. Indirect bonding technique in orthodontics

    National Research Council Canada - National Science Library

    Kübra Yıldırım; Banu Sağlam Aydınatay

    2016-01-01

    ‘Direct Bonding Technique’ which allows the fixed orthodontic appliances to be directly bonded to teeth without using bands decreased the clinic time for bracket bonding and increased esthetics and oral hygiene during orthodontic treatment...

  2. Transversely Compressed Bonded Joints

    DEFF Research Database (Denmark)

    Hansen, Christian Skodborg; Schmidt, Jacob Wittrup; Stang, Henrik

    2012-01-01

    The load capacity of bonded joints can be increased if transverse pressure is applied at the interface. The transverse pressure is assumed to introduce a Coulomb-friction contribution to the cohesive law for the interface. Response and load capacity for a bonded single-lap joint was derived using...... non-linear fracture mechanics. The results indicated a good correlation between theory and tests. Furthermore, the model is suggested as theoretical base for determining load capacity of bonded anchorages with transverse pressure, in externally reinforced concrete structures....

  3. Analysis of the M/M/N/N Queue with Two Types of Arrival Process: Applications to Future Mobile Radio Systems

    Directory of Open Access Journals (Sweden)

    Peter J. Smith

    2012-01-01

    Full Text Available The queueing system considered is essentially a M/M/N/N queue where two types of users compete for the N resources. The users may have different arrival and service rates and are denoted as primary or secondary users. The primary users have priority access to the resources, and three levels of priority are considered: perfect priority, partial priority, and no priority. This system models the recently developed cognitive radio concept, a methodology that has been proposed for future mobile radio systems. In this context, the primary users have certain rights to use the resources, whereas the secondary users must make opportunistic use of the resources without impacting too much on the performance of the primary users. For all priority settings, the mean number of primary and secondary users is derived as are the blocking probabilities for both users. When no priority is given to the primary user, the system collapses to a truncated form of two independent M/M/∞ queues. The product form solution for this special case is known, and, here, these results are given in a novel, compact form. In the case of nonzero priority, the dropping probability for the secondary users is also derived.

  4. Centers of projective vector fields of spatial quasi-homogeneous systems with weight $(m,m,n$ and degree $2$ on the sphere

    Directory of Open Access Journals (Sweden)

    Haihua Liang

    2016-11-01

    Full Text Available In this paper we study the centers of projective vector fields $\\mathbf{Q}_T$ of three-dimensional quasi-homogeneous differential system $d\\mathbf{x}/dt=\\mathbf{Q}(\\mathbf{x}$ with the weight $(m,m,n$ and degree $2$ on the unit sphere $\\mathbb{S}^2$. We seek the sufficient and necessary conditions under which $\\mathbf{Q}_T$ has at least one center on $\\mathbb{S}^2$. Moreover, we provide the exact number and the positions of the centers of $\\mathbf{Q}_T$. First we give the complete classification of systems $d\\mathbf{x}/dt=\\mathbf{Q}(\\mathbf{x}$ and then, using the induced systems of $\\mathbf{Q}_T$ on the local charts of $\\mathbb{S}^2,$ we determine the conditions for the existence of centers. The results of this paper provide a convenient criterion to find out all the centers of $\\mathbf{Q}_T$ on $\\mathbb{S}^2$ with $\\mathbf{Q}$ being the quasi-homogeneous polynomial vector field of weight $(m,m,n$ and degree $2$.

  5. Unusual H-Bond Topology and Bifurcated H-bonds in the 2-Fluoroethanol Trimer.

    Science.gov (United States)

    Thomas, Javix; Liu, Xunchen; Jäger, Wolfgang; Xu, Yunjie

    2015-09-28

    By using a combination of rotational spectroscopy and ab initio calculations, an unusual H-bond topology was revealed for the 2-fluoroethanol trimer. The trimer exhibits a strong heterochiral preference and adopts an open OH⋅⋅⋅OH H-bond topology while utilizing two types of bifurcated H-bonds involving organic fluorine. This is in stark contrast to the cyclic OH⋅⋅⋅OH H-bond topology adopted by trimers of water and other simple alcohols. The strengths of different H-bonds in the trimer were analyzed by using the quantum theory of atoms in molecules. The study showcases a remarkable example of a chirality-induced switch in H-bond topology in a simple transient chiral fluoroalcohol. It provides important insight into the H-bond topologies of small fluoroalcohol aggregates, which are proposed to play a key role in protein folding and in enantioselective reactions and separations where fluoroalcohols serve as a (co)solvent. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Safe and Liquid Mortgage Bonds

    DEFF Research Database (Denmark)

    Dick-Nielsen, Jens; Gyntelberg, Jacob; Lund, Jesper

    eliminates credit risk from the investor's perspective. Similar to other safe bonds, funding liquidity becomes the main driver of mortgage bond liquidity and this creates commonality in liquidity across markets and countries. These findings have implications for how to design a robust mortgage bond system......This paper shows that strict match pass-through funding of covered bonds provides safe and liquid mortgage bonds. Despite a 30% drop in house prices during the 2008 global crisis Danish mortgage bonds remained as liquid as most European government bonds. The Danish pass-through system effectively...... and for the treatment of covered bonds in capital regulation....

  7. The influence of age and depth of dentin on bonding.

    Science.gov (United States)

    Burrow, M F; Takakura, H; Nakajima, M; Inai, N; Tagami, J; Takatsu, T

    1994-07-01

    The purpose of this study was to investigate what influence the two variables of dentin depth and age may have on the tensile bond strengths of three bonding systems. Dentin discs prepared from human molars were divided into young and old, superficial and deep surfaces. Three bonding systems, Scotchbond Multi-purpose (3M Dental Products), Superbond D-liner (Sun Medical Co.), and Liner Bond II (Kuraray Co.) were the materials tested for tensile bond strength. In addition, the structural variation of the resin-impregnated, or hybrid, layer was compared among the two variables and three bonding systems. Tensile bond strengths exceeding 10 MPa were obtained for all materials. After ANOVA, an effect on tensile bond strength could be attributed to dentin age or depth for only Superbond D-liner used on deep-young dentin as compared with old-superficial dentin. All other group comparisons failed to show any variation between dentin depth or age. However, specimens bonded to deeper dentin showed slightly lower strengths. SEM observations showed thicker resin-impregnated layers for Scotchbond MP and Superbond D-liner compared with Liner Bond II. Liner Bond II exhibited a thinner and more diffuse resin-impregnated layer, believed to be due to the different dentin conditioning method. Dentin age or depth may not show as great an influence on bond strengths with the newer type of bonding systems. The resin-impregnated layer quality, rather than thickness, is believed to be the most important factor for obtaining high tensile bond strengths.

  8. Bonding with Your Baby

    Science.gov (United States)

    ... in infant massage in your area. Breastfeeding and bottle-feeding are both natural times for bonding. Infants respond ... milk you've pumped, the staff, including a lactation consultant, can help you make the transition to ...

  9. Handbook of wafer bonding

    CERN Document Server

    Ramm, Peter; Taklo, Maaike M V

    2011-01-01

    Written by an author and editor team from microsystems companies and industry-near research organizations, this handbook and reference presents dependable, first-hand information on bonding technologies.In the first part, researchers from companies and institutions around the world discuss the most reliable and reproducible technologies for the production of bonded wafers. The second part is devoted to current and emerging applications, including microresonators, biosensors and precise measuring devices.

  10. Denaturation and unfolding of human anaphylatoxin C3a: an unusually low covalent stability of its native disulfide bonds.

    Science.gov (United States)

    Chang, Jui-Yoa; Lin, Curtis C-J; Salamanca, Silvia; Pangburn, Michael K; Wetsel, Rick A

    2008-12-15

    The complement C3a anaphylatoxin is a major molecular mediator of innate immunity. It is a potent activator of mast cells, basophils and eosinophils and causes smooth muscle contraction. Structurally, C3a is a relatively small protein (77 amino acids) comprising a N-terminal domain connected by 3 native disulfide bonds and a helical C-terminal segment. The structural stability of C3a has been investigated here using three different methods: Disulfide scrambling; Differential CD spectroscopy; and Reductive unfolding. Two uncommon features regarding the stability of C3a and the structure of denatured C3a have been observed in this study. (a) There is an unusual disconnection between the conformational stability of C3a and the covalent stability of its three native disulfide bonds that is not seen with other disulfide proteins. As measured by both methods of disulfide scrambling and differential CD spectroscopy, the native C3a exhibits a global conformational stability that is comparable to numerous proteins with similar size and disulfide content, all with mid-point denaturation of [GdmCl](1/2) at 3.4-5M. These proteins include hirudin, tick anticoagulant protein and leech carboxypeptidase inhibitor. However, the native disulfide bonds of C3a is 150-1000 fold less stable than those proteins as evaluated by the method of reductive unfolding. The 3 native disulfide bonds of C3a can be collectively and quantitatively reduced with as low as 1mM of dithiothreitol within 5 min. The fragility of the native disulfide bonds of C3a has not yet been observed with other native disulfide proteins. (b) Using the method of disulfide scrambling, denatured C3a was shown to consist of diverse isomers adopting varied extent of unfolding. Among them, the most extensively unfolded isomer of denatured C3a is found to assume beads-form disulfide pattern, comprising Cys(36)-Cys(49) and two disulfide bonds formed by two pair of consecutive cysteines, Cys(22)-Cys(23) and Cys(56)-Cys(57), a

  11. Phase evolution and magnetic characteristics of TiFeNiCr and TiFeNiCrM (M = Mn, Co) high entropy alloys

    Science.gov (United States)

    Mishra, Rajesh K.; Shahi, Rohit R.

    2017-11-01

    The report describes the effect of elemental addition (Mn and Co) on the phase evolution and magnetic properties of equiatomic TiFeNiCr based high entropy alloys (HEAs). HEAs were synthesized through mechanical alloying (MA) of constituent elements for different milling duration. XRD analysis confirms that simple solid solution of face cantered cubic structure is formed for all the three selected HEAs. Double FCC and a sigma phase are evolved for TiFeNiCr and TiFeNiCrMn HEAs. However, for TiFeNiCrCo HEA single FCC phase is formed. Synthesized HEAs show soft magnetic characteristics and the value of saturation magnetization increases as the content of magnetic element increases. Moreover, the investigation also describes the effect of annealing on phase evolution and magnetic properties of synthesized HEAs. The value of saturation magnetization altered for annealed TiFeNiCrM (M = Mn, Co) HEAs.

  12. Ab-Initio Study on Plutonium Compounds Pu3M (M=Al, Ga, In), PuNp and Elemental Neptunium

    Energy Technology Data Exchange (ETDEWEB)

    Kutepov, A L

    2005-09-07

    Using spin-polarized relativistic density functional theory the electronic and magnetic structures for the plutonium compounds Pu{sub 3}M(M = Al; Ga; In) and PuNp have been investigated. For the first group of compounds the enhanced hybridization between Pu 5f and p-states of alloying element, as it has been found in spin-polarized calculations, is believed to be the main reason for the higher formation energies obtained in such kind of studies in comparison with the non-spin-polarized case. Also, comparative analysis of the actinides U, Np, Pu, Am, and Cm has been performed based on their electronic and magnetic structure. Some noticeable difference in the calculated magnetic structure was discovered between the actinide with local magnetic moments (Cm) and the actinides (Pu, Am) in which magnetic moments were found only in the calculations.

  13. Fundamentals of fiber bonding in thermally point-bonded nonwovens

    Science.gov (United States)

    Chidambaram, Aparna

    Thermal point bonding (TPB) uses heat and pressure to bond a web of fibers at discrete points imparting strength to the manufactured fabric. This process significantly reduces the strength and elongation of the bridging fibers between bond points while strengthening the web. Single fiber experiments were performed with four structurally different polypropylene fibers to analyze the inter-relationships between fiber structure, fiber properties and bonding process. Two fiber types had a low birefringence sheath or surface layer while the remaining had uniform birefringence profiles through their thickness. Bonds were formed between isolated pairs of fibers by subjecting the fibers to a calendering process and simulating TPB process conditions. The dependence of bond strength on bonding temperature and on the type of fiber used was evaluated. Fiber strengths before and after bonding were measured and compared to understand the effect of bonding on fiber strength. Additionally, bonded fiber strength was compared to the strength of single fibers which had experienced the same process conditions as the bonded pairs. This comparison estimated the effect of mechanical damage from pressing fibers together with steel rolls while creating bonds in TPB. Interfiber bond strength increased with bonding temperature for all fiber types. Fiber strength decreased with increasing bonding temperature for all fiber types except for one type of low birefringent sheath fibers. Fiber strength degradation was unavoidable at temperatures required for successful bonding. Mechanical damage from compression of fibers between rolls was an insignificant factor in this strength loss. Thermal damage during bonding was the sole significant contributor to fiber strength degradation. Fibers with low birefringence skins formed strong bonds with minimal fiber strength loss and were superior to fibers without such surface layers in TPB performance. A simple model to predict the behavior of a two-bond

  14. Exhibits Enhanced by Stand-Alone Computers.

    Science.gov (United States)

    Van Rennes, Eve C.

    Both the development and evaluation of one of a set of computer programs designed for use by visitors as adjuncts to museum exhibits are described. Museum displays used were (1) a static, behind-glass exhibit on evolution; (2) a hands-on primitive stone age tools exhibit; and (3) a Foucault pendulum. A computer placed next to each exhibit served…

  15. One-pot synthesis of M (M = Ag, Au)@SiO2 yolk-shell structures via an organosilane-assisted method: preparation, formation mechanism and application in heterogeneous catalysis.

    Science.gov (United States)

    Chen, Yu; Wang, Qihua; Wang, Tingmei

    2015-05-21

    We demonstrate the fabrication of yolk-shell catalysts consisting of a single M (M = Ag, Au) nanoparticle encapsulated within a hollow mesoporous organosilica shell via an organosilane-assisted strategy. The advantages of our method lie in its good controllability of the void space as well as the thickness of the mesoporous shell. The M@CTAB/SiO2 synthesized through a modified Stöber method can transform to yolk-shell structures after adding (3-aminopropyl)trimethoxysilane (APTMS)/TEOS or (3-aminopropyl)triethoxysilane (APTES)/TEOS into the synthetic medium. We give unambiguous evidence that the middle CTAB/SiO2 layer transforms into a less dense APTMS-rich organic-inorganic layer which was selectively removed in alkaline aqueous solution, while the amino-functionalized hybrid shells remain intact. Moreover, we discuss the role of alkylamino groups in the shell in the transformation from Ag@SiO2 nanorattles to hollow structures when impregnating the as-synthesized Ag@SiO2 nanorattles in HAuCl4 aqueous solution. The nanorattles also exhibit high catalytic activity for the catalytic reduction of p-nitrophenol.

  16. Nanostructure, hydrogen bonding and rheology in choline chloride deep eutectic solvents as a function of the hydrogen bond donor.

    Science.gov (United States)

    Stefanovic, Ryan; Ludwig, Michael; Webber, Grant B; Atkin, Rob; Page, Alister J

    2017-01-25

    Deep eutectic solvents (DESs) are a mixture of a salt and a molecular hydrogen bond donor, which form a eutectic liquid with a depressed melting point. Quantum mechanical molecular dynamics (QM/MD) simulations have been used to probe the 1 : 2 choline chloride-urea (ChCl : U), choline chloride-ethylene glycol (ChCl : EG) and choline chloride-glycerol (ChCl : Gly) DESs. DES nanostructure and interactions between the ions is used to rationalise differences in DES eutectic point temperatures and viscosity. Simulations show that the structure of the bulk hydrogen bond donor is largely preserved for hydroxyl based hydrogen bond donors (ChCl:Gly and ChCl:EG), resulting in a smaller melting point depression. By contrast, ChCl:U exhibits a well-established hydrogen bond network between the salt and hydrogen bond donor, leading to a larger melting point depression. This extensive hydrogen bond network in ChCl:U also leads to substantially higher viscosity, compared to ChCl:EG and ChCl:Gly. Of the two hydroxyl based DESs, ChCl:Gly also exhibits a higher viscosity than ChCl:EG. This is attributed to the over-saturation of hydrogen bond donor groups in the ChCl:Gly bulk, which leads to more extensive hydrogen bond donor self-interaction and hence higher cohesive forces within the bulk liquid.

  17. Romanian government bond market

    Directory of Open Access Journals (Sweden)

    Cornelia POP

    2012-12-01

    Full Text Available The present paper aims to present the level of development reached by Romanian government bond market segment, as part of the country financial market. The analysis will be descriptive (the data series available for Romania are short, based on the secondary data offered by the official bodies involved in the process of issuing and trading the Romanian government bonds (Romanian Ministry of Public Finance, Romanian National Bank and Bucharest Stock Exchange, and also on secondary data provided by the Federation of European Stock Exchanges.To enhance the market credibility as a benchmark, a various combination of measures is necessary; among these measures are mentioned: the extension of the yield curve; the issuance calendars in order to improve transparency; increasing the disclosure of information on public debt issuance and statistics; holding regular meetings with dealers, institutional investors and rating agencies; introducing a system of primary dealers; establishing a repurchase (repo market in the government bond market. These measures will be discussed based on the evolution presented inside the paper.The paper conclude with the fact that, until now, the Romanian government bond market did not provide a benchmark for the domestic financial market and that further efforts are needed in order to increase the government bond market transparency and liquidity.

  18. Asymmetric bifurcated halogen bonds.

    Science.gov (United States)

    Novák, Martin; Foroutan-Nejad, Cina; Marek, Radek

    2015-03-07

    Halogen bonding (XB) is being extensively explored for its potential use in advanced materials and drug design. Despite significant progress in describing this interaction by theoretical and experimental methods, the chemical nature remains somewhat elusive, and it seems to vary with the selected system. In this work we present a detailed DFT analysis of three-center asymmetric halogen bond (XB) formed between dihalogen molecules and variously 4-substituted 1,2-dimethoxybenzene. The energy decomposition, orbital, and electron density analyses suggest that the contribution of electrostatic stabilization is comparable with that of non-electrostatic factors. Both terms increase parallel with increasing negative charge of the electron donor molecule in our model systems. Depending on the orientation of the dihalogen molecules, this bifurcated interaction may be classified as 'σ-hole - lone pair' or 'σ-hole - π' halogen bonds. Arrangement of the XB investigated here deviates significantly from a recent IUPAC definition of XB and, in analogy to the hydrogen bonding, the term bifurcated halogen bond (BXB) seems to be appropriate for this type of interaction.

  19. Strength of Chemical Bonds

    Science.gov (United States)

    Christian, Jerry D.

    1973-01-01

    Students are not generally made aware of the extraordinary magnitude of the strengths of chemical bonds in terms of the forces required to pull them apart. Molecular bonds are usually considered in terms of the energies required to break them, and we are not astonished at the values encountered. For example, the Cl2 bond energy, 57.00 kcal/mole, amounts to only 9.46 x 10(sup -20) cal/molecule, a very small amount of energy, indeed, and impossible to measure directly. However, the forces involved in realizing the energy when breaking the bond operate over a very small distance, only 2.94 A, and, thus, f(sub ave) approx. equals De/(r - r(sub e)) must be very large. The forces involved in dissociating the molecule are discussed in the following. In consideration of average forces, the molecule shall be assumed arbitrarily to be dissociated when the atoms are far enough separated so that the potential, relative to that of the infinitely separated atoms, is reduced by 99.5% from the potential of the molecule at the equilibrium bond length (r(sub e)) for Cl2 of 1.988 A this occurs at 4.928 A.

  20. Analysis of tensile bond strengths using Weibull statistics.

    Science.gov (United States)

    Burrow, Michael F; Thomas, David; Swain, Mike V; Tyas, Martin J

    2004-09-01

    Tensile strength tests of restorative resins bonded to dentin, and the resultant strengths of interfaces between the two, exhibit wide variability. Many variables can affect test results, including specimen preparation and storage, test rig design and experimental technique. However, the more fundamental source of variability, that associated with the brittle nature of the materials, has received little attention. This paper analyzes results from micro-tensile tests on unfilled resins and adhesive bonds between restorative resin composite and dentin in terms of reliability using the Weibull probability of failure method. Results for the tensile strengths of Scotchbond Multipurpose Adhesive (3M) and Clearfil LB Bond (Kuraray) bonding resins showed Weibull moduli (m) of 6.17 (95% confidence interval, 5.25-7.19) and 5.01 (95% confidence interval, 4.23-5.8). Analysis of results for micro-tensile tests on bond strengths to dentin gave moduli between 1.81 (Clearfil Liner Bond 2V) and 4.99 (Gluma One Bond, Kulzer). Material systems with m in this range do not have a well-defined strength. The Weibull approach also enables the size dependence of the strength to be estimated. An example where the bonding area was changed from 3.1 to 1.1 mm diameter is shown. Weibull analysis provides a method for determining the reliability of strength measurements in the analysis of data from bond strength and tensile tests on dental restorative materials.

  1. Exhibition of tunnel coupling of negatively charged dangling bonds on Si Surface Using Scanning Tunneling Microscope

    Science.gov (United States)

    Haider, M. Baseer; Livadaru, L.; Pitters, J.; Wolkow, R.

    2011-03-01

    We have performed Scanning tunneling microscopy study of hydrogen terminated Si (100). We will show that single Si atoms in a solid state environment can be served as quantum dots. These negatively charged quantum dots can be tunnel coupled to the nearby Si quantum dots. We will demonstrate that this tunnel coupling can be controlled by adjusting the separation between the two Si atomic quantum dots. Moreover electron occupation in the tunnel coupled Si quantum dots can be controlled. We have used this tunnel coupling effect of Si atomic quantum dots to fabricate Quantum Cellular Automata Cells. Quantum Cellular Automata are used to transmit binary information through electrostatic interaction between adjacent cells without the transfer of charge from one cell to the next. Devices based on Quantum Cellular Automata will consume much less power compared to the conventional transistor based devices. Moreover, since there is no transfer of charge so power dissipation during its operation is minimal compared to conventional semiconductor devices. This Si based Quantum Cellular Automat Cell works at room temperature.

  2. Bond strength comparison of color change adhesives for orthodontic bonding.

    Science.gov (United States)

    Duers, Michael W; English, Jeryl D; Ontiveros, Joe C; Powers, John M; Bussa, Harry I; Frey, Gary N; Gallerano, Ronald L; Paige, Sebastian Z

    2011-03-01

    This study investigated whether three different color change light-cured orthodontic bonding adhesives have comparable shear bond strengths to a conventional light-cured orthodontic bonding adhesive. The sample of 240 bovine incisors was divided into four groups of 60 each. Each group tested one of four orthodontic bonding adhesives: 3M Unitek Transbond PLUS, Ormco Gréngloo, Ormco Blúgloo, and 3M Unitek Transbond XT (control). The four groups were further divided into two subgroups of 30 with shear bond strength tested at two different times (15 minutes and 24 hours) post-bond. The shear bond strength was measured on a universal testing machine. The data were analyzed by two-way analysis of variance and post-hoc comparisons (Fisher's PLSD) at the 0.05 level of significance. The average shear bond strength was greater at 24 hours than at 15 minutes for Transbond PLUS, Blúgloo, and Transbond XT. For Gréngloo, the average shear bond strength was greater at 15 minutes than at 24 hours. Gréngloo tested at 15 minutes had the highest average shear bond strength. Gréngloo tested at 24 hours had the lowest average shear bond strength. All four orthodontic bonding adhesives demonstrated bond strengths considered to be clinically acceptable for orthodontic purposes.

  3. [Direct bonding in orthodontics].

    Science.gov (United States)

    Hablützel, W

    1976-03-01

    Composite materials have been used to attach orthodontic brackets on the conditioned enamel surface. A method of direct bonding with Enamelite of metal brackets with a mechanical retention on the basis is described. Clinical experience with the adhesive technique, its range of indication and possible failures are discussed in several case reports.

  4. Bond strength variation of synthetic resin teeth in dentures.

    Science.gov (United States)

    Cunningham, J L; Benington, I C

    1995-01-01

    The bond strength of denture teeth to acrylic resin denture bases was determined by producing tensile test specimens from standardised and anonymously presented partial dentures. Ten dentures were produced by randomly selected commercial dental laboratories and five were produced in a university dental laboratory. The tooth debonding forces exhibited a wide range of variation both within and between dentures. The university-produced dentures showed, on average, a slightly improved tooth bond strength. This study highlights the need for further investigation of this problem and for the development of a standardised technique to provide satisfactory denture tooth bonding.

  5. Synthesis of PtM (M=Co, Ni)/Reduced Graphene Oxide Nanocomposites as Electrocatalysts for the Oxygen Reduction Reaction.

    Science.gov (United States)

    Li, Jialiang; Fu, Xinning; Mao, Zhou; Yang, Yushi; Qiu, Tong; Wu, Qingzhi

    2016-12-01

    A series of PtM (M=Co, Ni)/reduced graphene oxide (rG-O) nanocomposites were successfully synthesized through a facile hydrothermal method. The as-synthesized nanocomposites were characterized using transmission electron microscopy and high-resolution transmission electron microscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectrometer, and X-ray photoelectron spectroscopy. The electrochemical performance and oxygen reduction reaction (ORR) activity of PtM/rG-O nanocomposites were evaluated using cyclic voltammetry and the rotating disk electrode method. The results show that the addition of the reductant (1,2-hexadecanediol, HAD) in the reaction system slightly improved the ORR activity of PtM/rG-O nanocomposites with a negligible influence on the size and morphology of alloy NPs. Furthermore, PtNi/rG-O nanocomposites displayed the higher electrochemical stability than PtCo/rG-O nanocomposites. These results provide a facile strategy for the synthesis of Pt-based alloy NPs/rG-O nanocomposites for applications in catalysis and energy-related processes.

  6. Final report of AFRIMETS.M.M-S6: supplementary comparison of 100 mg, 100 g 500 g, 1 kg and 5 kg stainless steel mass standards

    Science.gov (United States)

    Mautjana, R. T.; Molefe, P. T.; Mayindu, N. F.; Armah, M. N.; Ramasawmy, V.; Albasini, G. L.; Matali, S.; Richmond, H.; Rusimbi, V.; Kiwanuka, J.; Mutale, D. M.; Mutsimba, F.

    2018-01-01

    This report summarizes the results of AFRIMETS.M.M-S6 mass standards comparison conducted between eleven participating laboratories/countries. Two sets of five weights with nominal values 100 mg, 100 g, 500 g, 1 kg and 5 kg were used as the traveling standards. These nominal values were decided from the needs of participating laboratories submitted to the pilot laboratory through a questionnaire and agreed upon by all participants. The traveling standards were hand carried between laboratories starting from February 2014 and were received from the last participants in October 2014. The programme was coordinated by National Metrology Institute of South Africa (NMISA), who provided the travelling standards and reference values for the comparison. The corrections to the BIPM as-maintained mass unit [5] have insignificant influence on the results of this comparison. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. Thermodynamic Constraints in Using AuM (M = Fe, Co, Ni, and Mo) Alloys as N₂ Dissociation Catalysts: Functionalizing a Plasmon-Active Metal.

    Science.gov (United States)

    Martirez, John Mark P; Carter, Emily A

    2016-02-23

    The Haber-Bosch process for NH3 synthesis is arguably one of the greatest inventions of the 20th century, with a massive footprint in agriculture and, historically, warfare. Current catalysts for this reaction use Fe for N2 activation, conducted at high temperatures and pressures to improve conversion rate and efficiency. A recent finding shows that plasmonic metal nanoparticles can either generate highly reactive electrons and holes or induce resonant surface excitations through plasmonic decay, which catalyze dissociation and redox reactions under mild conditions. It is therefore appealing to consider AuM (M = Fe, Co, Ni, and Mo) alloys to combine the strongly plasmonic nature of Au and the catalytic nature of M metals toward N2 dissociation, which together might facilitate ammonia production. To this end, through density functional theory, we (i) explore the feasibility of forming these surface alloys, (ii) find a pathway that may stabilize/deactivate surface M substituents during fabrication, and (iii) define a complementary route to reactivate them under operational conditions. Finally, we evaluate their reactivity toward N2, as well as their ability to support a pathway for N2 dissociation with a low thermodynamic barrier. We find that AuFe possesses similar appealing qualities, including relative stability with respect to phase separation, reversibility of Fe oxidation and reduction, and reactivity toward N2. While AuMo achieves the best affinity toward N2, its strong propensity toward oxidation could greatly limit its use.

  8. Capturing Guest Dynamics in Metal-Organic Framework CPO-27-M (M = Mg, Zn) by (2)H Solid-State NMR Spectroscopy.

    Science.gov (United States)

    Xu, Jun; Sinelnikov, Regina; Huang, Yining

    2016-06-07

    Metal-organic frameworks (MOFs) are promising porous materials for gas separation and storage as well as sensing. In particular, a series of isostructural MOFs with coordinately unsaturated metal centers, namely, CPO-27-M or M-MOF-74 (M = Mg, Zn, Mn, Fe, Ni, Co, Cu), have shown exceptional adsorption capacity and selectivity compared to those of classical MOFs that contain only fully coordinated metal sites. Although it is widely accepted that the interaction between guest molecules and exposed metal centers is responsible for good selectivity and large maximum uptake, the investigation of such guest-metal interaction is very challenging because adsorbed molecules are usually disordered in the pores and undergo rapid thermal motions. (2)H solid-state NMR (SSNMR) spectroscopy is one of the most extensively used techniques for capturing guest dynamics in porous materials. In this work, variable-temperature (2)H wide-line SSNMR experiments were performed on CPO-27-M (M = Mg, Zn) loaded with four prototypical guest molecules: D2O, CD3CN, acetone-d6, and C6D6. The results indicate that different guest molecules possess distinct dynamic behaviors inside the channel of CPO-27-M. For a given guest molecule, its dynamic behavior also depends on the nature of the metal centers. The binding strength of guest molecules is discussed on the basis of the (2)H SSNMR data.

  9. Investigating Design Research Landscapes through Exhibition

    DEFF Research Database (Denmark)

    Jönsson, Li; Hansen, Flemming Tvede; Mäkelä, Maarit

    2013-01-01

    What characterizes a design research exhibition compared to a traditional design and art exhibition? How do you show the very materialities of the design experiments as a means for communicating knowledge of research and of practice? How do you present, review and utilize such an exhibition? With...

  10. Towards a unified description of the hydrogen bond network of liquid water: a dynamics based approach.

    Science.gov (United States)

    Ozkanlar, Abdullah; Zhou, Tiecheng; Clark, Aurora E

    2014-12-07

    The definition of a hydrogen bond (H-bond) is intimately related to the topological and dynamic properties of the hydrogen bond network within liquid water. The development of a universal H-bond definition for water is an active area of research as it would remove many ambiguities in the network properties that derive from the fixed definition employed to assign whether a water dimer is hydrogen bonded. This work investigates the impact that an electronic-structure based definition, an energetic, and a geometric definition of the H-bond has upon both topological and dynamic network behavior of simulated water. In each definition, the use of a cutoff (either geometric or energetic) to assign the presence of a H-bond leads to the formation of transiently bonded or broken dimers, which have been quantified within the simulation data. The relative concentration of transient species, and their duration, results in two of the three definitions sharing similarities in either topological or dynamic features (H-bond distribution, H-bond lifetime, etc.), however no two definitions exhibit similar behavior for both classes of network properties. In fact, two networks with similar local network topology (as indicated by similar average H-bonds) can have dramatically different global network topology (as indicated by the defect state distributions) and altered H-bond lifetimes. A dynamics based correction scheme is then used to remove artificially transient H-bonds and to repair artificially broken bonds within the network such that the corrected network exhibits the same structural and dynamic properties for two H-bond definitions (the properties of the third definition being significantly improved). The algorithm described represents a significant step forward in the development of a unified hydrogen bond network whose properties are independent of the original hydrogen bond definition that is employed.

  11. The relative roles of electrostatics and dispersion in the stabilization of halogen bonds.

    Science.gov (United States)

    Riley, Kevin E; Hobza, Pavel

    2013-11-07

    In this work we highlight recent work aimed at the characterization of halogen bonds. Here we discuss the origins of the σ-hole, the modulation of halogen bond strength by changing of neighboring chemical groups (i.e. halogen bond tuning), the performance of various computational methods in treating halogen bonds, and the strength and character of the halogen bond, the dihalogen bond, and two hydrogen bonds in bromomethanol dimers (which serve as model complexes) are compared. Symmetry adapted perturbation theory analysis of halogen bonding complexes indicates that halogen bonds strongly depend on both dispersion and electrostatics. The electrostatic interaction that occurs between the halogen σ-hole and the electronegative halogen bond donor is responsible for the high degree of directionality exhibited by halogen bonds. Because these noncovalent interactions have a strong dispersion component, it is important that the computational method used to treat a halogen bonding system be chosen very carefully, with correlated methods (such as CCSD(T)) being optimal. It is also noted here that most forcefield-based molecular mechanics methods do not describe the halogen σ-hole, and thus are not suitable for treating systems with halogen bonds. Recent attempts to improve the molecular mechanics description of halogen bonds are also discussed.

  12. Indirect bonding technique in orthodontics

    Directory of Open Access Journals (Sweden)

    Kübra Yıldırım

    2016-08-01

    Full Text Available ‘Direct Bonding Technique’ which allows the fixed orthodontic appliances to be directly bonded to teeth without using bands decreased the clinic time for bracket bonding and increased esthetics and oral hygiene during orthodontic treatment. However, mistakes in bracket positioning were observed due to decreased direct visual sight and access to posterior teeth. ‘Indirect Bonding Technique’ was developed for eliminating these problems. Initially, decreased bond strength, higher bond failure rate, periodontal tissue irritation, compromised oral hygiene and increased laboratory time were the main disadvantages of this technique when compared to direct bonding. The newly developed materials and modified techniques help to eliminate these negative consequences. Today, the brackets bonded with indirect technique have similar bond strength with brackets bonded directly. Moreover, indirect and direct bonding techniques have similar effects on periodontal tissues. However, indirect bonding technique requires more attention and precision in laboratory and clinical stage, and has higher cost. Orthodontist's preference between these two bonding techniques may differ according to time spent in laboratory and clinic, cost, patient comfort and personal opinion.

  13. Affordances and distributed cognition in museum exhibitions

    DEFF Research Database (Denmark)

    Achiam, Marianne; May, Michael; Marandino, Martha

    2014-01-01

    consistent framework. Here, we invoke the notions of affordance and distributed cognition to explain in a coherent way how visitors interact with exhibits and exhibit spaces and make meaning from those interactions, and we exemplify our points using observations of twelve visitors to exhibits at a natural...... history museum. We show how differences in exhibit characteristics give rise to differences in the interpretive strategies used by visitors in their meaning-making process, and conclude by discussing how the notions of affordance and distributed cognition can be used in an exhibit design perspective....

  14. Comparison of shear bond strength of the stainless steel metallic brackets bonded by three bonding systems

    Directory of Open Access Journals (Sweden)

    Mehdi Ravadgar

    2013-09-01

    Full Text Available Introduction: In orthodontic treatment, it is essential to establish a satisfactory bond between enamel and bracket. After the self-etch primers (SEPs were introduced for the facilitation of bracket bonding in comparison to the conventional etch-and-bond system, multiple studies have been carried out on their shear bond strengths which have yielded different results. This study was aimed at comparing shear bond strengths of the stainless steel metallic brackets bonded by three bonding systems. Methods: In this experimental in vitro study, 60 extracted human maxillary premolar teeth were randomly divided into three equal groups: in the first group, Transbond XT (TBXT light cured composite was bonded with Transbond plus self-etching primer (TPSEP; in the second group, TBXT composite was bonded with the conventional method of acid etching; and in the third group, the self cured composite Unite TM bonding adhesive was bonded with the conventional method of acid etching. In all the groups, Standard edgewise-022 metallic brackets (American Orthodontics, Sheboygan, USA were used. Twenty-four hours after the completion of thermocycling, shear bond strength of brackets was measured by Universal Testing Machine (Zwick. In order to compare the shear bond strengths of the groups, the variance analysis test (ANOVA was adopted and p≤0.05 was considered as a significant level. Results: Based on megapascal, the average shear bond strength for the first, second, and third groups was 8.27±1.9, 9.78±2, and 8.92±2.5, respectively. There was no significant difference in the shear bond strength of the groups. Conclusions: Since TPSEP shear bond strength is approximately at the level of the conventional method of acid etching and within the desirable range for orthodontic brackets shear bond strength, applying TPSEP can serve as a substitute for the conventional method of etch and bond, particularly in orthodontic operations.

  15. Wafer bonding using Cu-Sn intermetallic bonding layers

    NARCIS (Netherlands)

    Flötgen, C.; Pawlak, M.; Pabo, E.; Wiel, H.J. van de; Hayes, G.R.; Dragoi, V.

    2014-01-01

    Wafer-level Cu-Sn intermetallic bonding is an interesting process for advanced applications in the area of MEMS and 3D interconnects. The existence of two intermetallic phases for Cu-Sn system makes the wafer bonding process challenging. The impact of process parameters on final bonding layer

  16. Making Weak Bonds (cooling) and Breaking Strong Bonds (heating ...

    Indian Academy of Sciences (India)

    Making Weak Bonds (cooling) and Breaking Strong Bonds (heating) with Supersonic Techniques · Acknowledgements · Outline · Slide 4 · A comparison of the two techniques · What is a hydrogen bond? Phenylacetylene and its complexes · Slide 8 · Phenylacetylene and PAH · phenylacetylene · Complexes in the interstellar ...

  17. A Heuristic for Improving Transmedia Exhibition Experience

    DEFF Research Database (Denmark)

    Selvadurai, Vashanth; Rosenstand, Claus Andreas Foss

    2017-01-01

    The area of interest is transmedia experiences in exhibitions. The research question is: How to involve visitors in a transmedia experience for an existing exhibition, which bridges the pre-, during- and post-experience? Research through design, and action research are the methods used to design...... and reflect on a transmedia experience for an existing exhibition. This is framed with literature about exhibitions and transmedia, and analyzed with quantitative data from a case-study of visitors in the exhibition; this is organizationally contextualized. The contribution covers a significant gap...... in the scientific field of designing transmedia experience in an exhibition context that links the pre- and post-activities to the actual visit (during-activities). The result of this study is a preliminary heuristic for establishing a relation between the platform and content complexity in transmedia exhibitions....

  18. A chelating-bond breaking and re-linking technique for rapid re-immobilization of immune micro-sensors.

    Science.gov (United States)

    Xu, Tiegang; Yu, Haitao; Xu, Pengchen; Li, Xinxin

    2012-04-01

    With high sensitivity and specificity to antigen, immune micro-sensors can be used in rapid detection of pathogenic microbial. This study proposes and develops a method for rapidly regeneration of antibody on a resonant micro-cantilever sensor. A nitrilotriacetic acid (NTA) derivative is synthesized with cystine and bromoacetic acid, then added with 2-mercaptoethanol to prepare a mixed self-assembled monolayer (SAM) on Au (111) surface of the cantilever. Ni²⁺ ions are thereafter chelated on the mixed SAM to form a breakable and re-linkable chelating-bond layer. Repeatable cycles of antibody immobilization and erasing are experimentally validated with a detectable marker of synthesized biotinylated poly peptides harboring six histidine residues (named as His-Bio). Two distinguished pathogenic microbial, Escherichia. coli O157:H7 and Bacillus Anthracis, are detected with the rapidly regenerated sensor. The E. coli O157:H7 sensor exhibits a three-time repeated detection to the 10³ CFU/ml concentration microbial. Then, an E. coli O157:H7 sensor is eluted with Tris-HCl (20 mM Tris, 150 mM NaCl, 0.1% Tween 20, pH = 3.0) and rapidly reconstructed into a B. Anthracis sensor by changing the re-immobilized antibody. The cantilever sensor no longer responses to E. coli O157:H7 even in a high concentration of 10⁷ CFU/ml. In contrast, the sensor is experimentally confirmed being resoluble to low concentration B. Anthracis at 10³ spores/ml level. The proposed fast regeneration method is promising in repeatedly or multi-target detection applications of micro/nano immune-sensors, e.g. the resonant micro-cantilevers.

  19. Hydrogen Bonding and Vibrational Spectroscopy: A Theoretical Study

    Science.gov (United States)

    Chaban, Galina M.

    2005-01-01

    Effects of hydrogen bonding on vibrational spectra are studied for several hydrogen-bonded complexes, in which hydrogen bonding ranges from weak (25 kcal/mol). The systems studied include complexes of inorganic acids and salts with water and ammonia, as well as complexes of several organic molecules (nitriles and amino acids) with water. Since anharmonic effects are very strong in hydrogen-bonded systems, anharmonic vibrational frequencies and infrared intensities are computed using the correlation-corrected vibrational self-consistent field (CC-VSCF) method with ab initio potential surfaces at the MP2 and CCSD(T) levels. The most common spectral effects induced by hydrogen bonding are red shifts of stretching vibrational frequencies ranging from approx.200/cm to over 2000/cm and significant increases of infrared intensities for those bonds that participate in hydrogen bonding. However, some systems (e.g. nitrile-water complexes) exhibit shifts in the opposite direction (to the blue) upon formation of hydrogen bonds.

  20. Sequential bond energies and structures of the Cr +·(N2)n, n =1−4

    Indian Academy of Sciences (India)

    The di-ligated complex exhibits the strongest bond dissociation energy among these four Cr. +·(N2)n (n = 1—4) complexes since it has the largest. Cr. +. —N bond order. Keywords. Density functional theory; nitrogen; chromium ion; bond dissociation energy; π back donation. 1. Introduction. Transition metal complexes of N2 ...

  1. Bond yield curve construction

    Directory of Open Access Journals (Sweden)

    Kožul Nataša

    2014-01-01

    Full Text Available In the broadest sense, yield curve indicates the market's view of the evolution of interest rates over time. However, given that cost of borrowing it closely linked to creditworthiness (ability to repay, different yield curves will apply to different currencies, market sectors, or even individual issuers. As government borrowing is indicative of interest rate levels available to other market players in a particular country, and considering that bond issuance still remains the dominant form of sovereign debt, this paper describes yield curve construction using bonds. The relationship between zero-coupon yield, par yield and yield to maturity is given and their usage in determining curve discount factors is described. Their usage in deriving forward rates and pricing related derivative instruments is also discussed.

  2. Space exhibitions: the science encounters the public

    Science.gov (United States)

    Coliolo, F.; Menendez, M.

    The widespread dissemination of science has always been one pillar of the development of human knowledge. There are several methods to structure interaction with the public: media, conferences, various written genres, and exhibitions. But: how to attract the public? How to arouse interest among future generation, insatiable for knowledge? In this paper we focus on space exhibitions, whose content combines mystery, discovery and science. The preparation of an exhibition is based on guidelines discussed between an interdisciplinary team and the exhibition project manager, the purpose of which is to find a coherent "strategy" to select information and to choose a concise, efficient, smart and original way to "visualize" the messages. Exhibition visitors are "privileged" because the interactivity is first emotive, then mental and cultural; the audience is universal. The goal of an exhibition is not to explain the content, but to stimulate the audience's curiosity in an attractive environment. We show some photos of ESA exhibitions, and try to understand if the visual impact is the first step towards a "multi-sensory" approach to communication. "A good exhibition can never be replaced by a book, a film or a lecture. A good exhibition creates a thirst for books, film, lectures. A good exhibition changes the visitors"(J. Wagensberg, Modern scientific museology")

  3. Optimal Investment in Structured Bonds

    DEFF Research Database (Denmark)

    Jessen, Pernille; Jørgensen, Peter Løchte

    The paper examines the role of structured bonds in the optimal portfolio of a small retail investor. We consider the typical structured bond essentially repacking an exotic option and a zero coupon bond, i.e. an investment with portfolio insurance. The optimal portfolio is found when the investment...

  4. Integration of European Bond Markets

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    2014-01-01

    I investigate the time variation in the integration of EU government bond markets. The integration is measured by the explanatory power of European factor portfolios for the individual bond markets for each year. The integration of the government bond markets is stronger for EMU than non...

  5. 46 CFR Sec. 10 - Bonds.

    Science.gov (United States)

    2010-10-01

    ...) shall be used. (b) In compliance with the perform- ance bond and payment bond requirements of Article 14... November 1950) respectively, shall be used. Such bonds (in the respective penal sums of 50 percent of the... penal sum of 40 percent of such job order contract price) shall guarantee the Contractor's performance...

  6. The chemical bond in inorganic chemistry the bond valence model

    CERN Document Server

    Brown, I David

    2016-01-01

    The bond valence model is a version of the ionic model in which the chemical constraints are expressed in terms of localized chemical bonds formed by the valence charge of the atoms. Theorems derived from the properties of the electrostatic flux predict the rules obeyed by both ionic and covalent bonds. They make quantitative predictions of coordination number, crystal structure, bond lengths and bond angles. Bond stability depends on the matching of the bonding strengths of the atoms, while the conflicting requirements of chemistry and space lead to the structural instabilities responsible for the unusual physical properties displayed by some materials. The model has applications in many fields ranging from mineralogy to molecular biology.

  7. Expectations, Bond Yields and Monetary Policy

    DEFF Research Database (Denmark)

    Chun, Albert Lee

    2011-01-01

    Through explicitly incorporating analysts' forecasts as observable factors in a dynamic arbitrage-free model of the yield curve, this research proposes a framework for studying the impact of shifts in market sentiment on interest rates of all maturities. An empirical examination reveals that surv...... of this type may provide traders and policymakers with a new set of tools for formally assessing the reaction of bond yields to shifts in market expectations......Through explicitly incorporating analysts' forecasts as observable factors in a dynamic arbitrage-free model of the yield curve, this research proposes a framework for studying the impact of shifts in market sentiment on interest rates of all maturities. An empirical examination reveals that survey...... expectations about inflation, output growth, and the anticipated path of monetary policy actions contain important information for explaining movements in bond yields. Estimates from a forward-looking monetary policy rule suggest that the central bank exhibits a preemptive response to inflationary expectations...

  8. Relationship between chemical structure and supramolecular effective molarity for formation of intramolecular H-bonds.

    Science.gov (United States)

    Sun, Hongmei; Hunter, Christopher A; Navarro, Cristina; Turega, Simon

    2013-09-04

    Effective molarity (EM) is a key parameter that determines the efficiency of a range of supramolecular phenomena from the folding of macromolecules to multivalent ligand binding. Coordination complexes formed between zinc porphyrins equipped H-bond donor sites and pyridine ligands equipped with H-bond acceptor sites have allowed systematic quantification of EM values for the formation of intramolecular H-bonds in 240 different systems. The results provide insights into the relationship of EM to supramolecular architecture, H-bond strength, and solvent. Previous studies on ligands equipped with phosphonate diester and ether H-bond acceptors were inconclusive, but the experiments described here on ligands equipped with phosphine oxide, amide, and ester H-bond acceptors resolve these ambiguities. Chemical double-mutant cycles were used to dissect the thermodynamic contributions of individual H-bond interactions to the overall stabilities of the complexes and hence determine the values of EM, which fall in the range 1-1000 mM. Solvent has little effect on EM, and the values measured in toluene and 1,1,2,2-tetrachloroethane are similar. For H-bond acceptors that have similar geometries but different H-bond strengths (amide and ester), the values of EM are very similar. For H-bond acceptors that have different geometries but similar H-bond strengths (amide and phosphonate diester), there is little correlation between the values of EM. These results imply that supramolecular EMs are independent of solvent and intrinsic H-bond strength but depend on supramolecular architecture and geometric complementarity.

  9. Which exhibition attributes create repeat visitation?

    OpenAIRE

    Whitfield, J.; Webber, D. J.

    2011-01-01

    This study identifies exhibition attributes deemed important by attendees’ in determining their attendance at the UK biennial MICROSCIENCE 2008 exhibition using a self-administered internet-based questionnaire. Perceived performance of attributes by attendees is also established. Attendees consider meeting specialists as well as gaining product and technical information to be very important attributes for exhibition selection. Application of an Importance Performance Analysis suggests that re...

  10. Hydrogen bonding in ionic liquids.

    Science.gov (United States)

    Hunt, Patricia A; Ashworth, Claire R; Matthews, Richard P

    2015-03-07

    Ionic liquids (IL) and hydrogen bonding (H-bonding) are two diverse fields for which there is a developing recognition of significant overlap. Doubly ionic H-bonds occur when a H-bond forms between a cation and anion, and are a key feature of ILs. Doubly ionic H-bonds represent a wide area of H-bonding which has yet to be fully recognised, characterised or explored. H-bonds in ILs (both protic and aprotic) are bifurcated and chelating, and unlike many molecular liquids a significant variety of distinct H-bonds are formed between different types and numbers of donor and acceptor sites within a given IL. Traditional more neutral H-bonds can also be formed in functionalised ILs, adding a further level of complexity. Ab initio computed parameters; association energies, partial charges, density descriptors as encompassed by the QTAIM methodology (ρBCP), qualitative molecular orbital theory and NBO analysis provide established and robust mechanisms for understanding and interpreting traditional neutral and ionic H-bonds. In this review the applicability and extension of these parameters to describe and quantify the doubly ionic H-bond has been explored. Estimating the H-bonding energy is difficult because at a fundamental level the H-bond and ionic interaction are coupled. The NBO and QTAIM methodologies, unlike the total energy, are local descriptors and therefore can be used to directly compare neutral, ionic and doubly ionic H-bonds. The charged nature of the ions influences the ionic characteristics of the H-bond and vice versa, in addition the close association of the ions leads to enhanced orbital overlap and covalent contributions. The charge on the ions raises the energy of the Ylp and lowers the energy of the X-H σ* NBOs resulting in greater charge transfer, strengthening the H-bond. Using this range of parameters and comparing doubly ionic H-bonds to more traditional neutral and ionic H-bonds it is clear that doubly ionic H-bonds cover the full range of weak

  11. Atomically Bonded Transparent Superhydrophobic Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Aytug, Tolga [ORNL

    2015-08-01

    Maintaining clarity and avoiding the accumulation of water and dirt on optically transparent surfaces such as US military vehicle windshields, viewports, periscope optical head windows, and electronic equipment cover glasses are critical to providing a high level of visibility, improved survivability, and much-needed safety for warfighters in the field. Through a combination of physical vapor deposition techniques and the exploitation of metastable phase separation in low-alkali borosilicate, a novel technology was developed for the fabrication of optically transparent, porous nanostructured silica thin film coatings that are strongly bonded to glass platforms. The nanotextured films, initially structurally superhydrophilic, exhibit superior superhydrophobicity, hence antisoiling ability, following a simple but robust modification in surface chemistry. The surfaces yield water droplet contact angles as high as 172°. Moreover, the nanostructured nature of these coatings provides increased light scattering in the UV regime and reduced reflectivity (i.e., enhanced transmission) over a broad range of the visible spectrum. In addition to these functionalities, the coatings exhibit superior mechanical resistance to abrasion and are thermally stable to temperatures approaching 500°C. The overall process technology relies on industry standard equipment and inherently scalable manufacturing processes and demands only nontoxic, naturally abundant, and inexpensive base materials. Such coatings, applied to the optical components of current and future combat equipment and military vehicles will provide a significant strategic advantage for warfighters. The inherent self-cleaning properties of such superhydrophobic coatings will also mitigate biofouling of optical windows exposed to high-humidity conditions and can help decrease repair/replacement costs, reduce maintenance, and increase readiness by limiting equipment downtime.

  12. Additional disulfide bonds in insulin

    DEFF Research Database (Denmark)

    Vinther, Tine N; Pettersson, Ingrid; Huus, Kasper

    2015-01-01

    The structure of insulin, a glucose homeostasis-controlling hormone, is highly conserved in all vertebrates and stabilized by three disulfide bonds. Recently, we designed a novel insulin analogue containing a fourth disulfide bond located between positions A10-B4. The N-terminus of insulin's B......-chain is flexible and can adapt multiple conformations. We examined how well disulfide bond predictions algorithms could identify disulfide bonds in this region of insulin. In order to identify stable insulin analogues with additional disulfide bonds, which could be expressed, the Cβ cut-off distance had...... in comparison to analogues with additional disulfide bonds that were more difficult to predict. In contrast, addition of the fourth disulfide bond rendered all analogues resistant to fibrillation under stress conditions and all stable analogues bound to the insulin receptor with picomolar affinities. Thus...

  13. Aqueous solutions of MgSO3.6H2O:M (M = Co or Co+Ni) and nonlinear optics

    Science.gov (United States)

    Petkova, P.; Vasilev, P.; Mustafa, M.; Nedkov, V.; Tacheva, J.; Tzoukrovsky, Y.

    2015-01-01

    The cations of 3d metals in water and alcohol create aqueous complexes, with the creation and stability of the aqua cations are of particular importance. The number of water molecules connected with the metal by direct metal-oxygen bonds determines the properties of the complex. The traditional measurements of, for example, ions mobility, ostensible radii of the hydration ions and the entropy of hydration, do not yield detailed information for the aqua ions, which is why studies of their spectral properties becomes necessary. These properties depend on the composition and the symmetry of the surrounding medium. In this work, the absorption of the complexes [Co(H2O)6]2+ and [Co+Ni(H2O)6]2+ were measured in the spectral region 395 - 600 nm. The energies of the electron transitions in Co2+ were calculated and the role of the spin-orbit coupling was evaluated. The calculated and experimental Lorentz profiles of the complexes investigated are also presented.

  14. 18 CFR 156.5 - Exhibits.

    Science.gov (United States)

    2010-04-01

    ... local authorizations. (i) A copy of any certificate of public convenience and necessity or similar..., showing towns and communities to be served, and (b) gas producing and storage filed, or other sources of.... (8) Exhibit G-II—Flow diagram data. Exhibits G and G-I shall be accompanied by a statement of...

  15. 18 CFR 50.7 - Applications: exhibits.

    Science.gov (United States)

    2010-04-01

    ... ELECTRIC TRANSMISSION FACILITIES § 50.7 Applications: exhibits. Each exhibit must contain a title page..., and substations description including: (i) Conductor size and type; (ii) Type of structures; (iii... existing if applicable) substations or switching stations that will be associated with the proposed new...

  16. Encountering Nanotechnology in an Interactive Exhibition

    Science.gov (United States)

    Murriello, Sandra E.; Knobel, Marcelo

    2008-01-01

    This article offers findings from a learning sciences-informed evaluation of a nanoscience and nanotechnology exhibition called Nano-Aventura (NanoAdventure), based on four interactive-collaborative games and two narrated videos. This traveling exhibition was developed in Brazil by the Museu Exploratorio de Ciencias for children and teenagers…

  17. Let's play game exhibitions : A curator's perspective

    NARCIS (Netherlands)

    de Vos, Jesse; Glas, M.A.J.|info:eu-repo/dai/nl/330981447; van Vught, J.F.|info:eu-repo/dai/nl/413532682

    2017-01-01

    The Netherlands Institute for Sound and Vision is home to The Experience, a museum exhibiting the history of media in the Netherlands. For ten months in 2016 and 2017, The Experience hosted a temporary exhibition entitled Let’s YouTube . During the Let’s YouTube game month, we programmed a ten-day

  18. Science Fiction Exhibits as STEM Gateways

    Science.gov (United States)

    Robie, Samantha

    Women continue to hold less than a quarter of all STEM jobs in the United States, prompting many museums to develop programs and exhibits with the express goal of interesting young girls in scientific fields. At the same time, a number of recent museum exhibits have harnessed the popularity of pop culture and science fiction in order to interest general audiences in STEM subject matter, as well as using the exhibits as springboards to expand or shift mission goals and focus. Because science fiction appears to be successful at raising interest in STEM fields, it may be an effective way to garner the interest of young girls in STEM in particular. This research seeks to describe the ways in which museums are currently using science fiction exhibits to interest young girls in STEM fields and careers. Research focused on four institutions across the country hosting three separate exhibits, and included staff interviews and content analysis of exhibit descriptions, promotional materials, a summative evaluation and supplementary exhibit productions. In some ways, science fiction exhibits do serve young girls, primarily through the inclusion of female role models, staff awareness, and prototype testing to ensure interactives are attractive to girls as well as to boys. However, STEM appears to be underutilized, which may be partly due to a concern within the field that the outcome of targeting a specific gender could be construed as "stereotyping".

  19. A Heuristic for Improving Transmedia Exhibition Experience

    DEFF Research Database (Denmark)

    Selvadurai, Vashanth; Rosenstand, Claus Andreas Foss

    2017-01-01

    The area of interest is transmedia experiences in exhibitions. The research question is: How to involve visitors in a transmedia experience for an existing exhibition, which bridges the pre-, during- and post-experience? Research through design, and action research are the methods used to design ...

  20. Artefacts and the performance of an exhibition

    DEFF Research Database (Denmark)

    Svabo, Connie

    2008-01-01

    The article explores the role of mediating artefacts in children's encounters with a museum of natural history. Using actor network theory it explores how a specific artefact shapes the way users relate to exhibited objects and how the artefact guides users' movements in the exhibition. The media...

  1. Memory and Mourning: An Exhibit History

    Science.gov (United States)

    Eberle, Scott G.

    2005-01-01

    Mounted by the Strong Museum in Rochester, New York, in 1993, and traveling nationally thereafter, the exhibit Memory and Mourning provided historical and contemporary perspectives to help museum guests explore their own reactions to loss and grief. In the process the exhibit's development team encountered a range of philosophical, historical,…

  2. Paolo Gioli: An Exercise in Exhibition Making

    Directory of Open Access Journals (Sweden)

    Enrico Camporesi

    2015-07-01

    Full Text Available The text is thought as a brief museological and museographical journey of Paolo Gioli’s exhibition “Volti” [“Faces”], that allows the reader to go through the exhibition-making process, discussing, among others, the difficulties that I have encountered.

  3. High Quality Virtual Reality for Architectural Exhibitions

    DEFF Research Database (Denmark)

    Kreutzberg, Anette

    2016-01-01

    This paper will summarise the findings from creating and implementing a visually high quality Virtual Reality (VR) experiment as part of an international architecture exhibition. It was the aim to represent the architectural spatial qualities as well as the atmosphere created from combining natural...... and artificial lighting in a prominent not yet built project. The outcome is twofold: Findings concerning the integration of VR in an exhibition space and findings concerning the experience of the virtual space itself. In the exhibition, an important aspect was the unmanned exhibition space, requiring the VR...... and quantitative methods at two different occasions and setups after the exhibition, both showing a high degree of immersion and experience of reality....

  4. The Culture of Exhibitions and Conservation

    Directory of Open Access Journals (Sweden)

    Dimitrios Doumas

    2013-11-01

    Full Text Available The article reflects on temporary exhibitions from a theoretical as well as practical perspective. Regarded as a particularly effective mass-communication medium, exhibitions have a dual nature: they are scholarly undertakings, bringing off a curator’s vision and, simultaneously, they are projects with economic implications that need to be well managed and administered. The role of conservation in the making of temporary exhibitions, either in-house or touring, is here discussed in relation to how work is planned and prioritized as well as how time is managed and staff is allocated. Reference to weaknesses that lessen the crucial input of conservation in the decision-making process is also made. Much of the debate, which focuses on art exhibitions, concerns practicalities encountered in a private museum that extend from the very early stages of selecting objects for display to the mounting of an exhibition.

  5. Holland at CERN – Industrial exhibition

    CERN Multimedia

    GS Department

    2010-01-01

    Sponsored by EVD, an agency of the Dutch Ministry of the Economy From 8 to 11 November 2010 Industrial Exhibition Administration Building Bldg. 61 9-00 - 17-30 Twenty seven companies will present their latest technology at the industrial exhibition "Holland at CERN". Dutch industry will exhibit products and technologies which are related to the field of particle physics. Individual interviews will take place directly at the stands in the Main Building. The firms will contact relevant users/technicians but any user wishing to make contact with a particular firm is welcome to use the contact details which are available from each departmental secretariat or at the following URL: http://gs-dep.web.cern.ch/gs-dep/groups/sem/ls/Industrial_Exhibitions.htm#Industrial_exhibitions You will find the list of exhibitors below. LIST OF EXHIBITORS: Schelde Exotech Vernooy BV Triumph Group INCAA Computers DeMaCo Holland bv TNO Science & Industry Janssen Precision Engi...

  6. Creating σ-holes through the formation of beryllium bonds.

    Science.gov (United States)

    Brea, Oriana; Mó, Otilia; Yáñez, Manuel; Alkorta, Ibon; Elguero, José

    2015-09-01

    Through the use of ab initio theoretical models based on MP2/aug-cc-pVDZ-optimized geometries and CCSD(T)/aug-cc-pVTZ and CCSD(T)/aug-c-pVDZ total energies, it has been shown that the significant electron density rearrangements that follow the formation of a beryllium bond may lead to the appearance of a σ-hole in systems that previously do not exhibit this feature, such as CH3 OF, NO2 F, NO3 F, and other fluorine-containing systems. The creation of the σ-hole is another manifestation of the bond activation-reinforcement (BAR) rule. The appearance of a σ-hole on the F atoms of CH3 OF is due to the enhancement of the electronegativity of the O atom that participates in the beryllium bond. This atom recovers part of the charge transferred to Be by polarizing the valence density of the F into the bonding region. An analysis of the electron density shows that indeed this bond becomes reinforced, but the F atom becomes more electron deficient with the appearance of the σ-hole. Importantly, similar effects are also observed even when the atom participating in the beryllium bond is not directly attached to the F atom, as in NO2 F, NO3 F, or NCF. Hence, whereas the isolated CH3 OF, NO2 F, and NO3 F are unable to yield F⋅⋅⋅Base halogen bonds, their complexes with BeX2 derivatives are able to yield such bonds. Significant cooperative effects between the new halogen bond and the beryllium bond reinforce the strength of both noncovalent interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Museum Exhibitions: Optimizing Development Using Evaluation

    Science.gov (United States)

    Dusenbery, P. B.

    2002-12-01

    The Space Science Institute (SSI) of Boulder, Colorado, has recently developed two museum exhibits called the Space Weather Center and MarsQuest. It is currently planning to develop a third exhibit called InterActive Earth. The Space Weather Center was developed in partnership with various research missions at NASA's Goddard Space Flight Center. The development of these exhibitions included a comprehensive evaluation plan. I will report on the important role evaluation plays in exhibit design and development using MarsQuest and InterActive Earth as models. The centerpiece of SSI's Mars Education Program is the 5,000-square-foot traveling exhibition, MarsQuest: Exploring the Red Planet, which was developed with support from the National Science Foundation (NSF), NASA, and several corporate donors. The MarsQuest exhibit is nearing the end of a highly successful, fully-booked three-year tour. The Institute plans to send an enhanced and updated MarsQuest on a second three-year tour and is also developing Destination: Mars, a mini-version of MarsQuest designed for smaller venues. They are designed to inspire and empower participants to extend the excitement and science content of the exhibitions into classrooms and museum-based education programs in an ongoing fashion. The centerpiece of the InterActive Earth project is a traveling exhibit that will cover about 4,000 square feet. The major goal of the proposed exhibit is to introduce students and the public to the complexity of the interconnections in the Earth system, and thereby, to inspire them to better understand planet Earth. Evaluation must be an integral part of the exhibition development process. For MarsQuest, a 3-phase evaluation (front end, formative and summative) was conducted by Randi Korn and Associates in close association with the development team. Sampling procedures for all three evaluation phases ensured the participation of all audiences, including family groups, students, and adults. Each phase of

  8. Developing Foreign Bond Markets: The Arirang Bond Experience in Korea

    OpenAIRE

    Jonathan A. Batten; Peter G. Szilagyi

    2006-01-01

    This study investigates the development of Korea’s foreign bond (Arirang) market for won-denominated foreign bonds. We provide an institutional perspective and discuss the problems, concerns and key issues related to the development of this market. We find no evidence that Arirang issuance either crowded out local debt or had exchange rate implications. Overall, the Korean experience provides valuable lessons for other emerging nations seeking to build bond markets for local and foreign issue...

  9. Bonding by Hydroxide-Catalyzed Hydration and Dehydration

    Science.gov (United States)

    Gwo, Dz-Hung

    2008-01-01

    A simple, inexpensive method for bonding solid objects exploits hydroxide-catalyzed hydration and dehydration to form silicate-like networks in thin surface and interfacial layers between the objects. The method can be practiced at room temperature or over a wide range of temperatures. The method was developed especially to enable the formation of precise, reliable bonds between precise optical components. The bonds thus formed exhibit the precision and transparency of bonds formed by the conventional optical-contact method and the strength and reliability of high-temperature frit bonds. The method also lends itself to numerous non-optical applications in which there are requirements for precise bonds and/or requirements for bonds, whether precise or imprecise, that can reliably withstand severe environmental conditions. Categories of such non-optical applications include forming composite materials, coating substrates, forming laminate structures, and preparing objects of defined geometry and composition. The method is applicable to materials that either (1) can form silicate-like networks in the sense that they have silicate-like molecular structures that are extensible into silicate-like networks or (2) can be chemically linked to silicate-like networks by means of hydroxide-catalyzed hydration and dehydration. When hydrated, a material of either type features surface hydroxyl (-OH) groups. In this method, a silicate-like network that bonds two substrates can be formed either by a bonding material alone or by the bonding material together with material from either or both of the substrates. Typically, an aqueous hydroxide bonding solution is dispensed and allowed to flow between the mating surfaces by capillary action. If the surface figures of the substrates do not match precisely, bonding could be improved by including a filling material in the bonding solution. Preferably, the filling material should include at least one ingredient that can be hydrated to

  10. An AAAA–DDDD quadruple hydrogen-bond array.

    Science.gov (United States)

    Blight, Barry A; Hunter, Christopher A; Leigh, David A; McNab, Hamish; Thomson, Patrick I T

    2011-03-01

    Secondary electrostatic interactions between adjacent hydrogen bonds can have a significant effect on the stability of a supramolecular complex. In theory, the binding strength should be maximized if all the hydrogen-bond donors (D) are on one component and all the hydrogen-bond acceptors (A) are on the other. Here, we describe a readily accessible AAAA–DDDD quadruple hydrogen-bonding array that exhibits exceptionally strong binding for a small-molecule hydrogen-bonded complex in a range of different solvents (K(a) > 3 × 10(12) M(-1) in CH2Cl2, 1.5 × 10(6) M(-1) in CH3CN and 3.4 × 10(5) M(-1) in 10% v/v DMSO/CHCl3). The association constant in CH2Cl2 corresponds to a binding free energy (ΔG) in excess of –71 kJ mol(-1) (more than 20% of the thermodynamic stability of a carbon–carbon covalent bond), which is remarkable for a supramolecular complex held together by just four intercomponent hydrogen bonds.

  11. Inspection for kissing bonds in composite materials using vibration measurements

    Science.gov (United States)

    Adams, Douglas E.; Sharp, Nathan D.; Myrent, Noah; Sterkenburg, Ronald

    2011-04-01

    Improper bonding of composite structures can result in close contact cracks under compressive stresses, called kissing bonds. These bond defects are very difficult to detect using conventional inspection techniques such as tap testing or local ultrasonic scanning and can lead to local propagation of damage if the structure is subjected to crack opening stresses. A method is investigated for identifying kissing bonds in composite material repairs based on vibration measurements. A damage feature of the kissing bond is extracted from the response of the input-output measurement that is a function of the structural path. This path exhibits local decoupling associated with the close contact cracks. Experimental vibration measurements from sandwich composite materials are presented along with the results of the damage detection algorithm for the healthy sections of the material and the kissing bond sections. A vibration based inspection technique could increase the ability to detect kissing bonds in composite material repairs while decreasing inspection time. Benefits of this method of identification over conventional techniques include its robust, objective damage detection methodology and the reduced requirement for specimen preparation and surface texture when compared to ultrasonic scanning.

  12. A mini-exhibition with maximum content

    CERN Multimedia

    Laëtitia Pedroso

    2011-01-01

    The University of Budapest has been hosting a CERN mini-exhibition since 8 May. While smaller than the main travelling exhibition it has a number of major advantages: its compact design alleviates transport difficulties and makes it easier to find suitable venues in the Member States. Its content can be updated almost instantaneously and it will become even more interactive and high-tech as time goes by.   The exhibition on display in Budapest. The purpose of CERN's new mini-exhibition is to be more interactive and easier to install. Due to its size, the main travelling exhibition cannot be moved around quickly, which is why it stays in the same country for 4 to 6 months. But this means a long waiting list for the other Member States. To solve this problem, the Education Group has designed a new exhibition, which is smaller and thus easier to install. Smaller maybe, but no less rich in content, as the new exhibition conveys exactly the same messages as its larger counterpart. However, in the slimm...

  13. Bond strength of self-adhesive resin cements to tooth structure

    Directory of Open Access Journals (Sweden)

    Susan Hattar

    2015-04-01

    Conclusions: Regardless of their clinical simplicity, the self-adhesive resin cements examined in this study exhibit limited bond performance to tooth structures; therefore, these cements must be used with caution.

  14. Better Bonded Ethernet Load Balancing

    Energy Technology Data Exchange (ETDEWEB)

    Gabler, Jason

    2006-09-29

    When a High Performance Storage System's mover shuttles large amounts of data to storage over a single Ethernet device that single channel can rapidly become saturated. Using Linux Ethernet channel bonding to address this and similar situations was not, until now, a viable solution. The various modes in which channel bonding could be configured always offered some benefit but only under strict conditions or at a system resource cost that was greater than the benefit gained by using channel bonding. Newer bonding modes designed by various networking hardware companies, helpful in such networking scenarios, were already present in their own switches. However, Linux-based systems were unable to take advantage of those new modes as they had not yet been implemented in the Linux kernel bonding driver. So, except for basic fault tolerance, Linux channel bonding could not positively combine separate Ethernet devices to provide the necessary bandwidth.

  15. France at CERN – Industrial exhibition

    CERN Multimedia

    FP Department

    2012-01-01

    Industrial Exhibition Administration Building Bldg 61 – 1st Floor Tuesday 27 March: 9 a.m. – 5.30 p.m. Wednesday 28 March: 9 a.m. – 2 p.m.   About thirty French companies are presenting their latest technological advances during the industrial exhibition "France at CERN", featuring products and technologies specifically related to CERN activities. Individual B2B meetings can be organized with the sales and technical representatives of participating firms and will take place at either the companies’ exhibition stands or in conference rooms in the Main Building. Individuals wishing to make contact with one or more companies must use the contact details available from each secretariat of department or by using this link. B2B meetings will be coordinated by UBIFRANCE. You will also find the list of exhibiting and participating companies online here. This event is sponsored by the French subsidiary of RS Components, the most important distri...

  16. 18 CFR 32.2 - Required exhibits.

    Science.gov (United States)

    2010-04-01

    ... of operating such facilities. Exhibit B. A general or key map on a scale not greater than 20 miles to... facilities used for the generation and transmission of electric energy, indicating on said map the points...

  17. Communicating Complex Sciences by Means of Exhibitions

    Science.gov (United States)

    Schneider, S.

    2011-12-01

    Earth Sciences will have to take over the leading role in global sustainable policy and in discussions about climate change. Efforts to raise attention within the politically responsible communities as well as in the public are getting more and more support by executive and advisory boards all over the world. But how can you successfully communicate complex sciences? For example, to start communication about climate change, the first step is to encourage people to be concerned about climate change. After that, one has to start thinking about how to present data and how to include the presented data into an unprejudiced context. Therefore, the communication toolbox offers various methods to reach diverse audiences. The R&D programme GEOTECHNOLOGIEN conducts roving exhibitions as one of its most successful communication tools. With roving exhibitions GEOTECHNOLOGIEN is able to get in touch with different audiences at once. The main purpose and theme of these exhibitions is to convey the everyday means of climate change to the visitors. It is within the responsibility of science to communicate the effects of a phenomenon like climate change as well as the impact of research results to the everyday life of people. Currently, a GEOTECHNOLOGIEN roving exhibition on remote sensing with satellites deals with various issues of environmental research, including a chapter on climate change. By following the 3M-concept (Meaning - Memorable - Moving), exhibitions allow to connect the visitors daily environment and personal experiences with the presented issues and objects. Therefore, hands-on exhibits, exciting multimedia effects and high-tech artefacts have to be combined with interpretive text elements to highlight the daily significance of the scientific topics and the exhibition theme respectively. To create such an exhibition, strong conceptual planning has to be conducted. This includes the specification of stern financial as well as time wise milestones. In addition

  18. Why Should Governments Issue Bonds?

    OpenAIRE

    Romer, David

    1993-01-01

    This paper has three purposes. First, it shows that several recent arguments that the optimal nominal interest rate on government bonds is zero even when second best considerations are accounted for rest on perfect substitutes assumptions. Second, it characterizes the conditions under which the issue of interest-bearing bonds is desirable once these assumptions are relaxed. And third, it shows that these potential microeconomic benefits of bond issue are closely related to traditional macroec...

  19. Adhesives for orthodontic bracket bonding

    OpenAIRE

    Déborah Daniella Diniz Fonseca; Daene Patrícia Tenório Salvador da Costa; Renata Cimões; Lúcia Carneiro de Souza Beatrice; Ana Cláudia da Silva Araújo

    2010-01-01

    The advent of acid etching, introduced by Buonocore in 1955, brought the possibility of bonding between the bracket base and enamel, contributing to more esthetic and conservative orthodontics. This direct bracket bonding technique has brought benefits such as reduced cost and time in performing the treatment, as well as making it easier to perform oral hygiene. The aim of this study was to conduct a survey of published studies on orthodontic bracket bonding to dental enamel. It was verified ...

  20. [All-Russian hygienic exhibitions and museums].

    Science.gov (United States)

    Kuzybaeva, M P

    2011-01-01

    The material about the popularization of hygiene and health education in Russia in the second half of the 19th century to early 20th century through exhibition and museum activities has been collected for the first time and analyzed in the paper. The role of scientists and scientific medical societies in this process is noted. The significance of museum and exhibition activities in this area for the development of medical science is defined.

  1. Sex differences in science museum exhibit attraction

    Science.gov (United States)

    Arámbula Greenfield, Teresa

    This study examines the relative attraction of hands-on, interactive science museum exhibits for females and males. Studies have demonstrated that such exhibits can be effective learning experiences for children, with both academic and affective benefits. Other studies have shown that girls and boys do not always experience the same science-related educational opportunities and that, even when they do, they do not necessarily receive the same benefits from them. These early differences can lead to more serious educational and professional disparities later in life. As interactive museum exhibits represent a science experience that is-readily available to both girls and boys, the question arose as to whether they were being used similarly by the two groups as well as by adult women and men. It was found that both girls and boys used all types of exhibits, but that girls were more likely than boys to use puzzles and exhibits focusing on the human body; boys were more likely than girls to use computers and exhibits illustrating physical science principles. However, this was less true of children accompanied by adults (parents) than it was of unaccompanied children on school field trips who roamed the museum more freely.Received: 16 February 1994; Revised: 3 February 1995;

  2. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... circumstances both materials show good bonding, but the high purity material is excluded because of recrystallisation and the resulting loss of mechanical properties. The effect of cross stacking and roll bonding pre-strained sheets of the commercial purity material is investigated and some dependence...

  3. Wafer bonding applications and technology

    CERN Document Server

    Gösele, Ulrich

    2004-01-01

    During the past decade direct wafer bonding has developed into a mature materials integration technology. This book presents state-of-the-art reviews of the most important applications of wafer bonding written by experts from industry and academia. The topics include bonding-based fabrication methods of silicon-on-insulator, photonic crystals, VCSELs, SiGe-based FETs, MEMS together with hybrid integration and laser lift-off. The non-specialist will learn about the basics of wafer bonding and its various application areas, while the researcher in the field will find up-to-date information about this fast-moving area, including relevant patent information.

  4. A simplified indirect bonding technique

    Directory of Open Access Journals (Sweden)

    Radha Katiyar

    2014-01-01

    Full Text Available With the advent of lingual orthodontics, indirect bonding technique has become an integral part of practice. It involves placement of brackets initially on the models and then their transfer to teeth with the help of transfer trays. Problems encountered with current indirect bonding techniques used are (1 the possibility of adhesive flash remaining around the base of the brackets which requires removal (2 longer time required for the adhesive to gain enough bond strength for secure tray removal. The new simplified indirect bonding technique presented here overcomes both these problems.

  5. Evaluation of an alternative technique to optimize direct bonding of orthodontic brackets to temporary crowns.

    Science.gov (United States)

    Dias, Francilena Maria Campos Santos; Pinzan-Vercelino, Célia Regina Maio; Tavares, Rudys Rodolfo de Jesus; Gurgel, Júlio de Araújo; Bramante, Fausto Silva; Fialho, Melissa Nogueira Proença

    2015-01-01

    To compare shear bond strength of different direct bonding techniques of orthodontic brackets to acrylic resin surfaces. The sample comprised 64 discs of chemically activated acrylic resin (CAAR) randomly divided into four groups: discs in group 1 were bonded by means of light-cured composite resin (conventional adhesive); discs in group 2 had surfaces roughened with a diamond bur followed by conventional direct bonding by means of light-cured composite resin; discs in group 3 were bonded by means of CAAR (alternative adhesive); and discs in group 4 had surfaces roughened with a diamond bur followed by direct bonding by means of CAAR. Shear bond strength values were determined after 24 hours by means of a universal testing machine at a speed of 0.5 mm/min, and compared by analysis of variance followed by post-hoc Tukey test. Adhesive remnant index (ARI) was measured and compared among groups by means of Kruskal-Wallis and Dunn tests. Groups 3 and 4 had significantly greater shear bond strength values in comparison to groups 1 and 2. Groups 3 and 4 yielded similar results. Group 2 showed better results when compared to group 1. In ARI analyses, groups 1 and 2 predominantly exhibited a score equal to 0, whereas groups 3 and 4 predominantly exhibited a score equal to 3. Direct bonding of brackets to acrylic resin surfaces using CAAR yielded better results than light-cured composite resin. Surface preparation with diamond bur only increased shear bond strength in group 2.

  6. Human Bond Communication

    DEFF Research Database (Denmark)

    Prasad, Ramjee

    2016-01-01

    Modern dexterous communication technology is progressively enabling humans to communicate their information through them with speech (aural) and media (optical) as underpinning essence. Humans realize this kind of aural and optical information by their optical and auditory senses. However, due...... to certain constraints, the ability to incorporate the other three sensory features namely, olfactory, gustatory, and tactile are still far from reality. Human bond communication is a novel concept that incorporates olfactory, gustatory, and tactile that will allow more expressive and holistic sensory...... information exchange through communication techniques for more human sentiment centric communication. This concept endorses the need of inclusion of other three senses and proposes an innovative approach of holistic communication for future communication network....

  7. Using Comparative Planetology in Exhibit Development

    Science.gov (United States)

    Dusenbery, P. B.; Harold, J. B.; Morrow, C. A.

    2004-12-01

    It is critically important for the public to better understand the scientific process. Museum exhibitions are an important part of informal science education that can effectively reach public audiences as well as school groups. They provide an important gateway for the public to learn about compelling scientific endeavors. The Space Science Institute (SSI) is a national leader in producing traveling science exhibitions and their associated educational programming (i.e. interactive websites, educator workshops, public talks, instructional materials). The focus of this presentation will be on three of its exhibit projects: MarsQuest (currently on tour), Alien Earths (in fabrication), and Giant Planets (in development). MarsQuest is enabling millions of Americans to share in the excitement of the scientific exploration of Mars and to learn more about their own planet in the process. Alien Earths will bring origins-related research and discoveries to students and the American public. It has four interrelated exhibit areas: Our Place in Space, Star Birth, PlanetQuest, and Search for Life. Exhibit visitors will explore the awesome events surrounding the birth of stars and planets; they will join scientists in the hunt for planets outside our solar system including those that may be in "habitable zones" around other stars; and finally they will be able to learn about how scientists are looking for signs of life beyond Earth. Giant Planets: Exploring the Outer Solar System will take advantage of the excitement generated by the Cassini mission and bring planetary and origins research and discoveries to students and the public. It will be organized around four thematic areas: Our Solar System; Colossal Worlds; Moons, Rings, and Fields; and Make Space for Kids. Giant Planets will open in 2007. This talk will focus on the importance of making Earth comparisons in the conceptual design of each exhibit and will show several examples of how these comparisons were manifested in

  8. ANÁLISE SOBRE OS MÉTODOS E ESTRATÉGIAS DE PERDA DE PESO EM ATLETAS DE MIXED MARTIAL ARTS (M.M.A. EM PERÍODO PRÉ-COMPETITIVO

    Directory of Open Access Journals (Sweden)

    Jessica Maria Leite de Oliveira e Silva

    2014-02-01

    Full Text Available Mixed Martial Arts (M.M.A. is a sport that combines various types of fight modes in a single combat rule. It requires heavy training and attention to all details of the mixed martial arts in order for the athlete to be 100% fit and precise in the day of the fight. The aim of this study was to evaluate the methods and strategies used in M.M.A. for weigh loss in the athlete’s physiological system, as well as to evaluate their performance. A questionnaire was given to the M.M.A. athletes for them to answer what they practice in order to accomplish rapid body mass loss. The program, Microsoft Excel 2007, was utilized for tab graphics. A total of 8 male athletes, from the ages of 21 to 35, responded to the questionnaire. The method used for weight loss by using sauna and antiperspirant clothes was 90% and the restriction of carbohydrate was 80% and liquid was 40%, being that this restriction and weight loss occurs in the pre-competitive week. These strategies cause harmful effects to the M.M.A. athletes, such as hormonal imbalance, electrolyte imbalance, cardiovascular system alterations, decreased renal function, impaired mental status in the long term, as well as mood changes. An Inadequate diet and short recovery time can lower the athlete's anaerobic performance, which prevails in M.M.A. This research can teach M.M.A athletes that through gradual changes and some nutritional rules, they can obtain a solution to impede rapid weight loss.

  9. Push-out bond strengths of two fiber post types bonded with different dentin bonding agents.

    Science.gov (United States)

    Topcu, Fulya Toksoy; Erdemir, Ugur; Sahinkesen, Gunes; Mumcu, Emre; Yildiz, Esra; Uslan, Ibrahim

    2010-05-01

    The aim of this study was to evaluate the regional push-out bond strengths for two fiber-reinforced post types using three different dentin bonding agents. Sixty single-rooted extracted human first premolar teeth were sectioned below the cemento-enamel junction, and the roots were endodontically treated. Following standardized post space preparations, the roots were divided into two fiber-post groups (Glassix and Carbopost), and further divided into three subgroups of 10 specimens each for the bonding systems self-etching dentin bonding agents (Clearfil SE Bond and Optibond all-in-one), and total-etching dentin bonding agent (XP Bond). A dual-cure resin luting cement (Maxcem) was then placed in the post spaces and posts were then seated into the root canals polymerized through the cervical portion. The roots were then cut into 3-mm thick sections. Push-out tests were performed at a crosshead speed of 0.5 mm/min. The data were analyzed with multivariate ANOVA (alpha = 0.05). The morphology of interface between different dentin bonding agents from the cervical sections were analyzed with SEM. Glass fiber-reinforced posts demonstrated significantly higher push-out bond strengths than carbon fiber-reinforced posts (p dentin adhesive Clearfil SE Bond and total-etching dentin adhesive XP Bond demonstrated similar bond strengths values and this was significantly higher compared with the Optibond all-in-one in cervical root canal region. In conclusion, in all root segments, the glass fiber-reinforced posts provided significantly increased post retention than the carbon fiber-reinforced posts, regardless of the adhesive used. (c) 2010 Wiley Periodicals, Inc.

  10. CERN exhibition a big hit in Bulgaria

    CERN Multimedia

    2005-01-01

    The first CERN exhibition in Bulgaria attracted many visitors. In the first ever CERN exhibition to be held in Bulgaria, over 1,400 visitors, many of them students and young physicists, visited the 10-day event in Sofia. The CERN mini-exhibition took place at the National Earth and Mankind Museum between 8 and 17 November. Permanently staffed by young physicists from Sofia University, there were exhibits on display about research activities at CERN, as well as four additional posters describing Bulgaria's participation. The inauguration took place on the morning of 8 November in the presence of the Vice-Minister for Science and Education, Mrs. Vanya Dobreva, and some 200 guests. A series of short speeches were followed by a visit to the exhibition. CERN's representative at the event, Ray Lewis, was then asked by Professor Matey Mateev, President of the Union of Physicists in Bulgaria, to say a few words on behalf of the Organization. Numerous journalists were also present at the inauguration. A painting enti...

  11. Influence of chain topology and bond potential on the glass transition of polymer chains simulated with the bond fluctuation model

    Energy Technology Data Exchange (ETDEWEB)

    Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), Senda del Rey 9, 28040 Madrid (Spain)], E-mail: jfreire@invi.uned.es

    2008-07-16

    The bond fluctuation model with a bond potential has been applied to investigation of the glass transition of linear chains and chains with a regular disposition of small branches. Cooling and subsequent heating curves are obtained for the chain energies and also for the mean acceptance probability of a bead jump. In order to mimic different trends to vitrification, a factor B gauging the strength of the bond potential with respect to the long-range potential (i.e. the intramolecular or intermolecular potential between indirectly bonded beads) has been introduced. (A higher value of B leads to a preference for the highest bond lengths and a higher total energy, implying a greater tendency to vitrify.) Different cases have been considered for linear chains: no long-range potential, no bond potential and several choices for B. Furthermore, two distinct values of B have been considered for alternate bonds in linear chains. In the case of the branched chains, mixed models with different values of B for bonds in the main chain and in the branches have also been investigated. The possible presence of ordering or crystallization has been characterized by calculating the collective light scattering function of the different samples after annealing at a convenient temperature below the onset of the abrupt change in the curves associated with a thermodynamic transition. It is concluded that ordering is inherited more efficiently in the systems with branched chains and also for higher values of B. The branched molecules with the highest B values in the main chain bonds exhibit two distinct transitions in the heating curves, which may be associated with two glass transitions. This behavior has been detected experimentally for chains with relatively long flexible branches.

  12. Optimal Investment in Structured Bonds

    DEFF Research Database (Denmark)

    Jessen, Pernille; Jørgensen, Peter Løchte

    2012-01-01

    of the article is to provide possible explanations for the puzzle of why small retail investors hold structured bonds. The investment universe consists of a stock index, a risk-free bank account, and a structured bond containing an option written on another index. We apply expected utility maximization...

  13. Distance criterion for hydrogen bond

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Distance criterion for hydrogen bond. In a D-H ...A contact, the D...A distance must be less than the sum of van der Waals Radii of the D and A atoms, for it to be a hydrogen bond.

  14. Fusion-bonded fluidic interconnects

    NARCIS (Netherlands)

    Fazal, I.; Elwenspoek, Michael Curt

    2008-01-01

    A new approach to realize fluidic interconnects based on the fusion bonding of glass tubes with silicon is presented. Fusion bond strength analyses have been carried out. Experiments with plain silicon wafers and coated with silicon oxide and silicon nitride are performed. The obtained results are

  15. Why are Hydrogen Bonds Directional?

    Indian Academy of Sciences (India)

    for an interaction to be characterized as a hydro- gen bond but does not provide any rationale for the same. This article reports a rationale for limiting the angle, based on the electron density topology using the quantum theory of atoms in molecules. Electron density topol- ogy for common hydrogen bond donors HF, HCl, ...

  16. The exploration of the exhibition informatization

    Science.gov (United States)

    Zhang, Jiankang

    2017-06-01

    The construction and management of exhibition informatization is the main task and choke point during the process of Chinese exhibition industry’s transformation and promotion. There are three key points expected to realize a breakthrough during the construction of Chinese exhibition informatization, and the three aspects respectively are adopting service outsourcing to construct and maintain the database, adopting advanced chest card technology to collect various kinds of information, developing statistics analysis to maintain good cutomer relations. The success of Chinese exhibition informatization mainly calls for mature suppliers who can provide construction and maintenance of database, the proven technology, a sense of data security, advanced chest card technology, the ability of data mining and analysis and the ability to improve the exhibition service basing on the commercial information got from the data analysis. Several data security measures are expected to apply during the process of system developing, including the measures of the terminal data security, the internet data security, the media data security, the storage data security and the application data security. The informatization of this process is based on the chest card designing. At present, there are several types of chest card technology: bar code chest card; two-dimension code card; magnetic stripe chest card; smart-chip chest card. The information got from the exhibition data will help the organizers to make relevant service strategies, quantify the accumulated indexes of the customers, and improve the level of the customer’s satisfaction and loyalty, what’s more, the information can also provide more additional services like the commercial trips, VIP ceremonial reception.

  17. Exhibits in libraries a practical guide

    CERN Document Server

    Brown, Mary E

    2005-01-01

    "Ccomprehensive...detailed"--Booklist; "thoroughly reseached...highly recommended"--Journal of Access Services. Library exhibits are more than entertainment for patrons. They can inspire and educate, stimulate an interest that can be explored in a book, or attract visitors who otherwise wouldn't stop by. Displays are also an opportunity for a library to put its creative foot forward or help patrons navigate the facility itself. This comprehensive "how-to" includes everything a librarian or staff member needs to know to put on an exhibit, from hatching ideas to evaluating the end result. Illustrations and photographs show practical methods of planning, labeling and displaying.

  18. SOCIAL BONDING: REGULATION BY NEUROPEPTIDES

    Directory of Open Access Journals (Sweden)

    Claudia eLieberwirth

    2014-06-01

    Full Text Available Affiliative social relationships (e.g., among spouses, family members, and friends play an essential role in human society. These relationships affect psychological, physiological, and behavioral functions. As positive and enduring bonds are critical for the overall well-being of humans, it is not surprising that considerable effort has been made to study the neurobiological mechanisms that underlie social bonding behaviors. The present review details the involvement of the nonapeptides, oxytocin (OT and arginine vasopressin (AVP, in the regulation of social bonding in mammals including humans. In particular, we will discuss the role of OT and AVP in the formation of social bonds between partners of a mating pair as well as between parents and their offspring. Furthermore, the role of OT and AVP in the formation of interpersonal bonding involving trust is also discussed.

  19. On the physical origin of the cation-anion intermediate bond in ionic liquids Part I. Placing a (weak) hydrogen bond between two charges.

    Science.gov (United States)

    Lehmann, Sebastian B C; Roatsch, Martin; Schöppke, Matthias; Kirchner, Barbara

    2010-07-21

    The intermediate bond forces in ionic liquids are investigated from static quantum chemical calculations at various methods and two basis sets. The experimentally observed red-shift of the donor-proton bond stretching frequency due to a bond elongation is confirmed by all methods. Comparing Hartree-Fock to second-order Møller-Plesset perturbation theory, the Hartree-Fock method gives in many cases an erroneous description of the geometries. Furthermore, the Hartree-Fock interaction energies can deviate up to 60 kJ mol(-1) from Møller-Plesset perturbation theory indicating the importance of dispersion interaction. While the usual trends of decreasing stability or interaction energies with increasing ion sizes are found, the geometries involving hydrogen atoms do not change this order of total interaction energies. Therefore, the hydrogen bond is not the most important interaction for ion pairs with regard to the total interaction energy. On the other hand, the different established analysis methods give rise to hydrogen bonding in several ion pairs. Charge analysis reveals the hydrogen-bonding character of the ion pair and shows, depending on the type of ions combined and further on the type of conformers considered, that a hydrogen bond can be present. The possibility of hydrogen bonding is also shown by an analysis of the frontier orbitals. Calculating potential energy surfaces and observing from this the change in the donor proton bond indicates that regular hydrogen bonds are possible in ion pairs of ionic liquids. Thereby, the maximum of bond elongation exceeds the one of a usual hydrogen bond by far. The more salt-like hydrogen-bonded ion pair [NH(4)][BF(4)] exhibits a steeper maximum than the more ionic liquid like ion pair [EtNH(3)][BF(4)]. The fact that imidazolium-based ionic liquids as [Emim][Cl] can display two faces, hydrogen bonding and purely ionic bonding, points to a disturbing rather than stabilizing role of hydrogen bonding on the interaction of

  20. Strong Ionic Hydrogen Bonding Causes a Spectral Isotope Effect in Photoactive Yellow Protein

    Science.gov (United States)

    Kaledhonkar, Sandip; Hara, Miwa; Stalcup, T. Page; Xie, Aihua; Hoff, Wouter D.

    2013-01-01

    Standard hydrogen bonds are of great importance for protein structure and function. Ionic hydrogen bonds often are significantly stronger than standard hydrogen bonds and exhibit unique properties, but their role in proteins is not well understood. We report that hydrogen/deuterium exchange causes a redshift in the visible absorbance spectrum of photoactive yellow protein (PYP). We expand the range of interpretable isotope effects by assigning this spectral isotope effect (SIE) to a functionally important hydrogen bond at the active site of PYP. The inverted sign and extent of this SIE is explained by the ionic nature and strength of this hydrogen bond. These results show the relevance of ionic hydrogen bonding for protein active sites, and reveal that the inverted SIE is a novel, to our knowledge, tool to probe ionic hydrogen bonds. Our results support a classification of hydrogen bonds that distinguishes the properties of ionic hydrogen bonds from those of both standard and low barrier hydrogen bonds, and show how this classification helps resolve a recent debate regarding active site hydrogen bonding in PYP. PMID:24314088

  1. Molecularly Tuning the Radicaloid N-H···O═C Hydrogen Bond.

    Science.gov (United States)

    Lu, Norman; Chung, Wei-Cheng; Ley, Rebecca M; Lin, Kwan-Yu; Francisco, Joseph S; Negishi, Ei-Ichi

    2016-03-03

    Substituent effects on the open shell N-H···O═C hydrogen-bond has never been reported. This study examines how 12 functional groups composed of electron donating groups (EDG), halogen atoms and electron withdrawing groups (EWG) affect the N-H···O═C hydrogen-bond properties in a six-membered cyclic model system of O═C(Y)-CH═C(X)N-H. It is found that group effects on this open shell H-bonding system are significant and have predictive trends when X = H and Y is varied. When Y is an EDG, the N-H···O═C hydrogen-bond is strengthened; and when Y is an EWG, the bond is weakened; whereas the variation in electronic properties of X group do not exhibit a significant impact upon the hydrogen bond strength. The structural impact of the stronger N-H···O═C hydrogen-bond are (1) shorter H and O distance, r(H···O) and (2) a longer N-H bond length, r(NH). The stronger N-H···O═C hydrogen-bond also acts to pull the H and O in toward one another which has an effect on the bond angles. Our findings show that there is a linear relationship between hydrogen-bond angle and N-H···O═C hydrogen-bond energy in this unusual H-bonding system. In addition, there is a linear correlation of the r(H···O) and the hydrogen bond energy. A short r(H···O) distance corresponds to a large hydrogen bond energy when Y is varied. The observed trends and findings have been validated using three different methods (UB3LYP, M06-2X, and UMP2) with two different basis sets.

  2. Hydrogen bond and lifetime dynamics in diluted alcohols.

    Science.gov (United States)

    Salamatova, Evgeniia; Cunha, Ana V; Shinokita, Keisuke; Jansen, Thomas L C; Pshenichnikov, Maxim S

    2017-10-25

    Hydrogen-bonding plays a crucial role in many chemical and biochemical reactions. Alcohols, with their hydrophilic and hydrophobic groups, constitute an important class of hydrogen-bonding molecules with functional tuning possibilities through changes in the hydrophobic tails. Recent studies demonstrated that for solutions of alcohols changes in the hydrophobic tail significantly affect a broad range of dynamics properties of the liquid. Still, the understanding is lacking on the origin of such differences in terms of a solvent- versus a solute-dominated effect. Here we reveal this origin by studying hydrogen-bond dynamics in a number of alcohol molecules - from methanol to butanol - diluted in a hydrogen-bond accepting environment, acetonitrile. The dynamics were investigated by pump-probe and 2D infrared spectroscopy combined with molecular dynamics-spectral simulations, using the OH stretching mode as a reporter. For all the considered alcohols, the vibrational lifetime of the OH stretching mode was found to be ∼3 ps. The hydrogen-bond dynamics exhibit similar behavior with a fast (∼200 fs) initial relaxation dominated by librational motion and a slow (∼4 ps) relaxation due to hydrogen-bond exchange dynamics. The similar dynamics over such a broad range of alcohols led us to conclude that the previously observed differences in dynamics in bulk alcohols originate from the dependence of the solvent properties on the hydrophobic tail, while the solute properties as found herein are essentially independent of the hydrophobic tail.

  3. Comic Strips to Accompany Science Museum Exhibits

    Science.gov (United States)

    Chung, Beom Sun; Park, Eun-mi; Kim, Sang-Hee; Cho, Sook-kyoung; Chung, Min Suk

    2016-01-01

    Science museums make the effort to create exhibits with amusing explanations. However, existing explanation signs with lengthy text are not appealing, and as such, visitors do not pay attention to them. In contrast, conspicuous comic strips composed of simple drawings and humors can attract science museum visitors. This study attempted to reveal…

  4. Do cylinders exhibit a cubatic phase?

    NARCIS (Netherlands)

    Blaak, R.; Frenkel, D.; Mulder, B.M.

    1999-01-01

    We investigate the possibility that freely rotating cylinders with an aspect ratio L/D = 0.9 exhibit a cubatic phase similar to the one found for a system of cut spheres. We present theoretical arguments why a cubatic phase might occur in this particular system. Monte Carlo simulations do not

  5. Synchronization in multicell systems exhibiting dynamic plasticity

    Indian Academy of Sciences (India)

    Using two perturbation analyses, we also show that this emergent synchronized dynamical state is fairly robust under external perturbations. Thus, the inherent plasticity in the oscillatory phenotypes in these model cells may get suppressed to exhibit collective dynamics of a single type in a multicell system, but ...

  6. CERN exhibition wins yet another design prize

    CERN Multimedia

    Joannah Caborn Wengler

    2012-01-01

    The “Universe of Particles” exhibition in CERN’s Globe wins the silver design prize from the German direct business communications association FAMAB.   Not only do tens of thousands of people visit the “Universe of Particles” exhibition each year, but juries for design prizes are crossing its threshold more and more frequently too. In 2011 alone it claimed 8 awards, including winning outright the 2011 Annual Multimedia award, the iF Communication Design for Corporate Architecture award and the Modern Decoration Media award (the Bulletin already reported on some of these in July 2011). The FAMAB award is the latest to join the prestigious list. The jury of FAMAB’s “ADAM 2011” award was particularly impressed by the hands-on nature of the exhibition, which encourages visitors to get interested in science. They also appreciated the way that the space in the Globe is not just a container for the exhibits, but itself ...

  7. 18 CFR 153.8 - Required exhibits.

    Science.gov (United States)

    2010-04-01

    ... facilities in the United States and Canada or Mexico; (5) Exhibit E. If the proposal is to import or export..., OR MODIFY FACILITIES USED FOR THE EXPORT OR IMPORT OF NATURAL GAS Application Under Section 3 § 153.8... for the export or the import of natural gas is within the authorized powers of applicant, that...

  8. Dentin-bonding agents

    Directory of Open Access Journals (Sweden)

    João Carlos Gomes

    2008-01-01

    Full Text Available New dental restorative materials have been developed to meet not only the functional demands, but esthetics as well, and in the last few years an enormous range of new materials has appeared for use in dentistry. Among them, several adhesive systems, and different operative techniques for each group materials. Therefore, is indispensable for the professional to know about the properties, characteristics, and association of these materials with the dental structures, in order to select and use them correctly. Should conventional self-etching adhesive systems be used? This question encouraged this literature review to be conducted, with the aim of comparing the conventional adhesive systems with the self-etching systems and to look for scientific data that would help professionals to choose which adhesive system to use. When compared to conventional systems, it was noted that the self-etching systems show less sensitivity to technique, especially as regards errors the operator could commit. The self-etching systems, particularly the 2-step type, have shown equivalent values of bond strength, marginal microleakage and performance, therefore, will be an option for direct composite resin restorations in posterior teeth.

  9. Direct Bonded Pontic (Laporan Kasus

    Directory of Open Access Journals (Sweden)

    Suhandi Sidjaja

    2015-10-01

    Full Text Available Advanced science and technology in dentistry enable dental practitioners to modified she bonding techniques in tooth replacement. A pontic made of composite resin bonded to etched enamel of the adjacent teeth can be used in the replacement of one missing anterior tooth with a virgin or sowed adpicent tooth. The advantages of this technique include a one visit treatment, cow cost, good esthetics, less side effects and easy repair or rebounding. Clinical evaluation showed a high success rate therefore with a proper diagnosis and a perfect skill of the direct bonded technique this treatment can be used as an alternative restoration.

  10. The chemisorptive bond basic concepts

    CERN Document Server

    Clark, Alfred

    1974-01-01

    The Chemisorptive Bond: Basic Concepts describes the basic concepts of the chemisorptive bond on solid surfaces from the simple analogies with ordinary chemical bonds to the quantum-mechanical approaches.This book is composed of 10 chapters and begins with discussions of simple formulas for correlating measurable quantities in chemisorptions and catalysis. The succeeding chapters deal with theories based on quantum-mechanical principles that describe the mutual interactions of atoms of the solid and foreign atoms on the surface. The remaining chapters consider the possible arrangements

  11. Corporate Bonds : Analyzing the availability of the Swedish bond market

    OpenAIRE

    Peterson, Rickard; Höglund, Linn; Jarnegren, Carl

    2006-01-01

    In the past, the Swedish bond market has been distinguished for its illiquidity and difficulties with retrieving information. This is the starting point of our thesis and the purpose is to analyze and describe the availability of the present corporate bond market for manufacturing firms in Sweden. In order to fulfill the purpose, a qualitative method was used and interviews with different operators of the market were conducted. Our respondents were sampled from large issuing companies, the ma...

  12. 77 FR 553 - Surety Companies Acceptable on Federal Bonds: Termination; Western Bonding Company

    Science.gov (United States)

    2012-01-05

    ... Fiscal Service Surety Companies Acceptable on Federal Bonds: Termination; Western Bonding Company AGENCY... Company (NAIC 13191) under 31 U.S.C. 9305 to qualify as an acceptable surety on Federal bonds is... bonds, including continuous bonds, currently in force with above listed Company, bond-approving officers...

  13. Effect of Ni interlayer on diffusion bonding of a W alloy and a Ta alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian; Liu, Ruxia; Wei, Qinqin; Luo, Guoqiang; Shen, Qiang; Zhang, Lianmeng [Wuhan Univ. of Technology (China). The State Key Lab. of Advanced Technology for Materials Synthesis and Processing

    2017-11-01

    The combination of W and Ta is expected to be highly beneficial for many applications from aerospace, weapons, military and nuclear industry. In this paper, W and Ta alloys were successfully diffusion bonded with Ni interlayer. The process of the formation of W/Ni/Ta diffusion bonded joints was investigated by means of scanning electron microscopy, X-ray diffraction system, electron probe micro-analyzer, energy dispersive spectrometry and shear strength measurement. The results show that the shear strength increases when the bonding temperature increases and exhibits a maximum value of 244 MPa at 930 C. The bonding of W/Ni can be attributed to the bonding of Ni to tungsten grains and the bonding of Ni to a Ni-Fe-binder mainly by elemental diffusion. The fracture takes place in the Ni/Ta interface and Ni{sub 3}Ta and Ni{sub 2}Ta intermetallic compounds are formed on the fracture surfaces.

  14. Effect of the Hydrogen Bond on Photochemical Synthesis of Silver Nanoparticles.

    Science.gov (United States)

    Zhao, Feng-jiao; Liu, Lei; Yang, Yang; Zhang, Rui-ling; Ren, Guang-hua; Xu, Da-li; Zhou, Pan-wang; Han, Ke-li

    2015-12-17

    The effect of a hydrogen bond on the photochemical synthesis of silver nanoparticles has been investigated via experimental and theoretical methods. In a benzophenone system, the photochemical synthesis process includes two steps, which are that hydrogen abstraction reaction and the following reduction reaction. We found that for the first step, an intermolecular hydrogen bond enhances the proton transfer. The efficiency of hydrogen abstraction increases with the hydrogen bond strength. For the second step, the hydrogen-bonded ketyl radical complex shows higher reducibility than the ketyl radical. The inductively coupled plasma-optical emission spectroscopy (ICP-OES) measurement exhibits a 2.49 times higher yield of silver nanoparticles in the hydrogen bond ketyl radical complex system than that for the ketyl radical system. Theoretical calculations show that the hydrogen bond accelerates electron transfer from the ketyl radical to the silver ion by raising the SOMO energy of the ketyl radical; thus, the SOMO-LUMO interaction is more favorable.

  15. Atomic bonding effects in annular dark field scanning transmission electron microscopy. I. Computational predictions

    Energy Technology Data Exchange (ETDEWEB)

    Odlyzko, Michael L.; Mkhoyan, K. Andre, E-mail: mkhoyan@umn.edu [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Himmetoglu, Burak [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 and Materials Department, University of California, Santa Barbara, California 93106 (United States); Cococcioni, Matteo [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 and Theory and Simulations of Materials, National Centre for Computational Design and Discovery of Novel Materials, École polytechnique fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2016-07-15

    Annular dark field scanning transmission electron microscopy (ADF-STEM) image simulations were performed for zone-axis-oriented light-element single crystals, using a multislice method adapted to include charge redistribution due to chemical bonding. Examination of these image simulations alongside calculations of the propagation of the focused electron probe reveal that the evolution of the probe intensity with thickness exhibits significant sensitivity to interatomic charge transfer, accounting for observed thickness-dependent bonding sensitivity of contrast in all ADF-STEM imaging conditions. Because changes in image contrast relative to conventional neutral atom simulations scale directly with the net interatomic charge transfer, the strongest effects are seen in crystals with highly polar bonding, while no effects are seen for nonpolar bonding. Although the bonding dependence of ADF-STEM image contrast varies with detector geometry, imaging parameters, and material temperature, these simulations predict the bonding effects to be experimentally measureable.

  16. Enhanced Mechanical Properties of Nanoparticle Networks Cross-Linked by Biomimetic Catch Bonds

    Science.gov (United States)

    Mbanga, Badel L.; Iyer, Balaji V. S.; Yashin, Victor V.; Balazs, Anna C.

    2015-03-01

    The tunable behavior of cross-linked networks of Polymer-Grafted Nanoparticles (PGNs) makes them excellent candidates for designing novel materials with enhanced mechanical properties. The building block of a PGN network is a nanoparticle with grafted polymer chains whose free ends' reactive groups can form bonds with the end chains on the nearby particles. We use computer modeling to study the tensile behavior of 3D samples, in which some fraction of cross-links is formed through the biomimetic ``catch'' bonds. In contrast to conventional ``slip'' bonds, the catch bonds might become stronger under an applied force due to transitions between two conformational states. The mechanical properties of the PGN networks are shown to exhibit a drastic improvement upon introduction of the catch bonds into the network. We discuss how ductility, toughness, and rate of strain recovery of the network depend on the catch bond content.

  17. Bond durability of resin cements to Au-Pd-Ag alloy under cyclic impact load.

    Science.gov (United States)

    Ohsawa, Masahiro; Yokota, Hiroaki; Yoshihiko, Hayashi

    2004-06-01

    The bond durability of resin cements to a 12% Au-Pd-Ag alloy was studied through cyclic impact tests with different loads. A piece of casting alloy was bonded to a cast block with two types of resin cements, Super Bond C&B and Bistite II. A shear load was applied onto a small piece of alloy until debonding of the specimen, using different weights of plungers, 130 g, 230 g, 330 g and 430 g. The specimen bonded with Super Bond exhibited a higher resistance than that with Bistite II. The fracture modes of the debonded cements were completely different from each other. That is, Bistite II showed a bulk fracture of cement by the crack penetrating through the cement layer. On the other hand, Super Bond showed damages limited to the surface and no bulk fracture. The mode of fracture was dependent not on the loading weight but the types of resin cements used.

  18. LHC INAUGURATION, LHC Fest highlights: exhibition time!

    CERN Multimedia

    2008-01-01

    David Gross, one of the twenty-one Nobel Laureates who have participated in the project.Tuesday 21 October 2008 Accelerating Nobels Colliding Charm, Atomic Cuisine, The Good Anomaly, A Quark Somewhere on the White Paper, Wire Proliferation, A Tale of Two Liquids … these are just some of the titles given to artworks by Physics Nobel Laureates who agreed to make drawings of their prize-winning discoveries (more or less reluctantly) during a special photo session. Science photographer Volker Steger made portraits of Physics Nobel Laureates and before the photo sessions he asked them to make a drawing of their most important discovery. The result is "Accelerating Nobels", an exhibition that combines unusual portraits of and original drawings by twenty-one Nobel laureates in physics whose work is closely related to CERN and the LHC. This exhibition will be one of the highlights of the LHC celebrations on 21 October in the SM18 hall b...

  19. Exhibition: Women and Sciences by Fiami

    CERN Multimedia

    Globe Info

    2011-01-01

    The 19-panel exhibition is on display at CERN's Microcosm from Monday to Saturday from 10.00 a.m. to 5.00 p.m.   Marie Curie won the Nobel Prize for Chemistry one hundred years ago. She is the only woman ever to win two Nobel Prizes, which is a testament to her remarkable work. But throughout history, women have played a role in science either in their own right or alongside other scientists. In this special exhibition, the comic-strip artist Fiami takes a look back at the relationship between women and science through his portraits of Mileva Einstein, Marie-Anne Lavoisier and, of course, Marie Curie. Fiami has recently published an entire album devoted to Marie Curie. Texts in French All ages - Entrance free Femmes et Sciences is on display at Microcosm: From Wednesday 21 September 2011 to Tuesday 20 December 2011.

  20. The palaeontological exhibition: a venue for dialogue.

    Science.gov (United States)

    Murriello, Sandra

    2015-01-01

    Understanding the dialogue between museums and their visitors enables museums to subsist, undergo transformations and become consolidated as socially valued cultural venues. The Museo de La Plata (Argentina) was created in the late nineteenth century as a natural history museum, and this study shows that currently the museum is valued socially as a venue for family leisure and education, at which people make sense to the objects exhibited through characteristics conferred upon them by both the institution and the visitor. Nevertheless, such dialogue is somehow affected by the museographic proposal and the public interpretation of the institutional narrative, which could be analysed within the frame of contextual learning. As a consequence, the evolutionary idea that the museum aims to communicate is distorted by the public. This article highlights the importance of considering the visitors' interpretations when planning museum exhibitions, a perspective that has been rather absent in the Argentinian museums. © The Author(s) 2014.

  1. Blebbishields and mitotic cells exhibit robust macropinocytosis.

    Science.gov (United States)

    Jinesh, Goodwin G; Kamat, Ashish M

    2017-03-01

    Cancer stem cells can survive and undergo transformation after apoptosis by initiating robust endocytosis. Endocytosis in-turn drives formation of serpentine filopodia, which promote construction of blebbishields from apoptotic bodies. However, the status and role of macropinocytosis in blebbishields is not known. Here, we show by scanning electron microscopy and by macropinocytosis assays that blebbishields exhibit robust macropinocytosis. Inhibiting dynamin-mediated endocytosis does not affect macropinocytosis in blebbishields or in mitotic cells. In addition, inhibiting macropinocytosis did not inhibit construction of blebbishields from apoptotic bodies. Thus, although apoptotic cancer stem cells exhibit robust macropinocytosis, macropinocytosis is not essential to generate blebbishields, although it may play other roles in blebbishield biology. © 2016 BioFactors, 43(2):181-186, 2017. © 2016 International Union of Biochemistry and Molecular Biology.

  2. CERN's new microcosm exhibition is now open

    CERN Multimedia

    2016-01-01

    After a major revamp in 2015, CERN’s microcosm exhibition is once again open to visitors. The exhibition is free and open to all without reservation and visitors are encouraged to share their #microcosm @CERN experiences on social media. Read more: http://cern.ch/go/7HWC -Producer- CERN Video Productions -Director- Kate Kahle -Camera- indissoluble.com and Julien Ordan -Editor- Julien Ordan -Infography- Daniel Dominguez Noemi Caraban -Music- “Light Years” by Stellardrone http://freemusicarchive.org/music/Ste... You can follow us on: cern.ch youtube.com/cerntv google.com/+CERN facebook.com/cern twitter.com/cern/ linkedin.com/company/cern instagram.com/cern Copyright © 2016 CERN. Terms of use: http://copyright.web.cern.ch/

  3. Fluorescence detection of cytosine/guanine transversion based on a hydrogen bond forming ligand.

    Science.gov (United States)

    Nishizawa, Seiichi; Yoshimoto, Keitaro; Seino, Takehiro; Xu, Chun-Yan; Minagawa, Masakazu; Satake, Hiroyuki; Tong, Aijun; Teramae, Norio

    2004-05-10

    In combination with abasic site (AP site)-containing oligodeoxynucleotides (ODNs), we demonstrate potential use of a hydrogen bond forming ligand, 2-amino-7-methyl-1,8-naphthyridine (AMND), for the fluorescence detection of the cytosine (C)/guanine (G) mutation sequence of the cancer repression gene p53. Our method is based on construction of the AP site in ODN duplexes, which allows small synthetic ligands to bind to target nucleobases accompanied by fluorescence signaling: an AP site-containing ODN is hybridized with a target ODN so as to place the AP site toward a target nucleobase, by which hydrophobic microenvironments are provided for ligands to recognize target nucleobases through hydrogen-bonding. In 10mM sodium cacodylate buffer solutions (pH, 7.0) containing 100mM NaCl and 1.0mM EDTA, AMND is found to strongly bind to C (K(d)=1.5x10(-6)M) in the target ODN while the binding affinity for G is relatively moderate (K(d)=50x10(-6)M). Significant fluorescence quenching of AMND is observed only when binding to C, making it possible to judge the C/G transversion with the naked eye.

  4. Craft Generation - Exhibition / Symposium / Workshops / Tour

    OpenAIRE

    Lamb, Andrew

    2015-01-01

    2014 saw a national programme celebrating 25 years of contemporary visual art under the banner of GENERATION.  \\ud \\ud FCA&C (Fife Contemporary Art & Craft) wanted to recognise and celebrate the achievements of Contemporary Scottish Craft practitioners, highlighting creativity, skills, and the career of key individuals as well as and the continuation and renewal of skill and Craftsmanship. \\ud \\ud Established craft artists will exhibited along with artists from the following generation whose ...

  5. PLATE: Product Lifetimes And The Environment Exhibition

    OpenAIRE

    Hanson, Maria

    2015-01-01

    The PLATE (Product Lifetimes And The Environment) Exhibition explored critical themes related to how long products last in contemporary society. The topic of product longevity is examined in innovative ways through prototypes, objects, artefacts, posters, photographs and films produced by designers, social businesses, artists, researchers, lecturers and students.\\ud \\ud Featuring household products, furniture, lighting, fashion, jewellery and artworks, this collection of visual work embraced ...

  6. Naval Meteorology and Oceanography Command exhibit entrance

    Science.gov (United States)

    2000-01-01

    StenniSphere at NASA's John C. Stennis Space Center in Hancock County, Miss., invites visitors to discover why America comes to Stennis Space Center before going into space. Designed to entertain while educating, StenniSphere includes informative displays and exhibits from NASA and other agencies located at Stennis, such as this one from the Naval Meteorology and Oceanography Command. Visitors can 'travel' three-dimensionally under the sea and check on the weather back home in the Weather Center.

  7. Naval Meteorology and Oceanography Command exhibit

    Science.gov (United States)

    2000-01-01

    Designed to entertain while educating, StenniSphere at the John C. Stennis Space Center in Hancock County, Miss., includes informative displays and exhibits from NASA and other agencies located at Stennis, such as this one from the Naval Meteorology and Oceanography Command. Visitors can 'travel' three-dimensionally under the sea and check on the weather back home in the Weather Center. StenniSphere is open free of charge from 9 a.m. to 5 p.m. daily.

  8. Exhibition: Dialogue between Science and religion

    CERN Multimedia

    2001-01-01

    Can the theory of the Big Bang reached by physicists and the concept of creation beloved of religion ever be reconciled? The two approaches have at least one point in common: they do not provide a final answer to the mysteries of the birth of the Universe. And this means that dialogue is alays possible between the two. It is to show the potential of such an exchange that Geneva's Société Evangélique organization is opening an exhibition under the title 'Big Bang and Creation', at the Planète Charmilles shopping centre, to run from 19 to 30 March. View of the 'Big Bang and Creation' exhibition. The exhibition is divided into three sections, showing the views of the scientist and those of the believer without setting them up in opposition to one another. In the first section, under a representation of the vault of heaven, the visitor will discover the different ideas explaining the birth of the Universe: Genesis and the Big Bang, and the different dominant theories ...

  9. Bumblebees exhibit the memory spacing effect

    Science.gov (United States)

    Toda, Nicholas R. T.; Song, Jeremy; Nieh, James C.

    2009-10-01

    Associative learning is key to how bees recognize and return to rewarding floral resources. It thus plays a major role in pollinator floral constancy and plant gene flow. Honeybees are the primary model for pollinator associative learning, but bumblebees play an important ecological role in a wider range of habitats, and their associative learning abilities are less well understood. We assayed learning with the proboscis extension reflex (PER), using a novel method for restraining bees (capsules) designed to improve bumblebee learning. We present the first results demonstrating that bumblebees exhibit the memory spacing effect. They improve their associative learning of odor and nectar reward by exhibiting increased memory acquisition, a component of long-term memory formation, when the time interval between rewarding trials is increased. Bombus impatiens forager memory acquisition (average discrimination index values) improved by 129% and 65% at inter-trial intervals (ITI) of 5 and 3 min, respectively, as compared to an ITI of 1 min. Memory acquisition rate also increased with increasing ITI. Encapsulation significantly increases olfactory memory acquisition. Ten times more foragers exhibited at least one PER response during training in capsules as compared to traditional PER harnesses. Thus, a novel conditioning assay, encapsulation, enabled us to improve bumblebee-learning acquisition and demonstrate that spaced learning results in better memory consolidation. Such spaced learning likely plays a role in forming long-term memories of rewarding floral resources.

  10. A model of hydrogen bond formation in phosphatidylethanolamine bilayers.

    Science.gov (United States)

    Pink, D A; McNeil, S; Quinn, B; Zuckermann, M J

    1998-01-19

    . The thickness of the headgroup layer underwent essentially no change on going from the gel to the fluid phase. The 2H NMR quadrupole splittings for the alpha and beta CH2 groups were 4.9 and 5.7kHz (fluid phase) and 7.1 and 7.3 kHz (gel phase), respectively, on the assumption of sufficiently rapid rotation around the z-axis. (iv) In both phases, the location of the NH3+ group exhibited a strong peak around 5.2 A into the aqueous medium, with much smaller peaks around 2.6 and 7.8 A, the two CH2 groups exhibited narrower, double-peaked distributions and the O and the PO2 each exhibited a narrow single peak. (v) PE headgroups, in a homogeneous gel phase, exhibited dipolar orientational long-range order in the plane of the bilayer. The distribution of orientation angles exhibited a full width at half height of between approximately 40 degrees and approximately 50 degrees. In a fluid phase no such order was observed. (vi) The number of hydrogen bonds did not differ substantially between the fluid and gel phases. This model is unlikely to display any significant effect of hydrogen bonding upon the "main" hydrocarbon chain melting phase transition at Tm, except, possibly, a broadening of any hysteresis, compared to the case of PC bilayers where interlipid hydrogen bonding is absent.

  11. Interface Phenomena and Bonding Mechanism in Magnetic Pulse Welding

    Science.gov (United States)

    Stern, A.; Shribman, V.; Ben-Artzy, A.; Aizenshtein, M.

    2014-10-01

    Magnetic pulse welding (MPW) is a solid-state impact welding technology that provides metallurgical joints while exhibiting a negligible heat-affected zone. The MPW process is a high speed single shot welding technique used mainly for joining tubular components in a lap configuration and characteristic length scales of few millimeters to centimeters. It is similar in operation to explosive welding and shares the same physical principles. The nature of bonding in MPW is not sufficiently understood yet and some controversial explanations are reported in the literature. The two major ideas are based on either solid state bonding or local melting and solidification. The present work summarizes our current understanding of the bonding mechanism and the structure in various similar and dissimilar metal pairs joined by MPW.

  12. Structural complexity in grain boundaries with covalent bonding

    Energy Technology Data Exchange (ETDEWEB)

    Tarnow, E.; Dallot, P.; Bristowe, P.D.; Joannopoulos, J.D. (Massachusetts Institute of Technology, Cambridge, MA (USA)); Francis, G.P.; Payne, M.C. (Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom))

    1990-08-15

    The structural properties of two short-period twist boundaries in germanium are explored using a state-of-the-art total-energy calculation. The structures of these boundaries are found to be very complex, with boundary bonds that are distorted and weak. These systems are found to exhibit a large degeneracy in the number of local energy minima. Thus the boundaries have difficulty in arriving at a locally ordered state. The situation may be unique to the {ital semiconducting} {ital twist} grain boundaries due to the inherent frustration present between the tendency to form directional bonds and the imposed twist geometry which makes the bond formation improbable. This study focuses on the energy, coordination, volume change, and electronic states characteristic of the local minima. A trend towards dimerization is found especially in the highest-angle twist boundary.

  13. Structural complexity in grain boundaries with covalent bonding

    Science.gov (United States)

    Tarnow, E.; Dallot, P.; Bristowe, P. D.; Joannopoulos, J. D.; Francis, G. P.; Payne, M. C.

    1990-08-01

    The structural properties of two short-period twist boundaries in germanium are explored using a state-of-the-art total-energy calculation. The structures of these boundaries are found to be very complex, with boundary bonds that are distorted and weak. These systems are found to exhibit a large degeneracy in the number of local energy minima. Thus the boundaries have difficulty in arriving at a locally ordered state. The situation may be unique to the semiconducting twist grain boundaries due to the inherent frustration present between the tendency to form directional bonds and the imposed twist geometry which makes the bond formation improbable. This study focuses on the energy, coordination, volume change, and electronic states characteristic of the local minima. A trend towards dimerization is found especially in the highest-angle twist boundary.

  14. Adhesives for orthodontic bracket bonding

    Directory of Open Access Journals (Sweden)

    Déborah Daniella Diniz Fonseca

    2010-04-01

    Full Text Available The advent of acid etching, introduced by Buonocore in 1955, brought the possibility of bonding between the bracket base and enamel, contributing to more esthetic and conservative orthodontics. This direct bracket bonding technique has brought benefits such as reduced cost and time in performing the treatment, as well as making it easier to perform oral hygiene. The aim of this study was to conduct a survey of published studies on orthodontic bracket bonding to dental enamel. It was verified that resin composites and glass ionomer are the most studied and researched materials for this purpose. Resin-modified glass ionomer, with its biocompatibility, capacity of releasing fluoride and no need for acid etching on the tooth structure, has become increasingly popular among dentists. However, due to the esthetic and mechanical properties of light polymerizable resin composite, it continues to be one of the adhesives of choice in the bracket bonding technique and its use is widely disseminated.

  15. “Evaluation of shear bond strength of a composite resin to white mineral trioxide aggregate with three different bonding systems”-An in vitro analysis

    Science.gov (United States)

    Patil, Anand C.

    2016-01-01

    Background Mineral trioxide aggregate (MTA) is a biomaterial that has been investigated for endodontic applications. With the increased use of MTA in pulp capping, pulpotomy, perforation repair, apexification and obturation, the material that would be placed over MTA as a final restoration is an important matter. As composite resins are one of the most widely used final restorative materials, this study was conducted to evaluate the shear bond strength of a composite resin to white mineral trioxide aggregate (WMTA) using three different bonding systems namely the two-step etch and rinse adhesive, the self-etching primer and the All-in-one system. Material and Methods Forty five specimens of white MTA (Angelus) were prepared and randomly divided into three groups of 15 specimens each depending on the bonding systems used respectively. In Group A, a Two-step etch and rinse adhesive or ‘total-etch adhesive’, Adper Single Bond 2 (3M/ESPE) and Filtek Z350 (3M ESPE, St Paul, MN) were placed over WMTA. In group B, a Two-step self-etching primer system, Clearfil SE Bond (Kuraray, Medical Inc) and Filtek Z350 were used. In Group C, an All-in-one system, G Bond (GC corporation, Tokyo, Japan) and Filtek Z350 were used. The shear bond strength was measured for all the specimens. The data obtained was subjected to One way Analysis of Variance (ANOVA) and Scheffe’s post hoc test. Results The results suggested that the Two-step etch and rinse adhesive when used to bond a composite resin to white MTA gave better bond strength values and the All-in-one exhibited the least bond strength values. Conclusions The placement of composite used with a Two-step etch and rinse adhesive over WMTA as a final restoration may be appropriate. Key words:Composite resins, dentin bonding agents, mineral trioxide aggregate, shear bond strength. PMID:27398177

  16. Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns.

    Science.gov (United States)

    Mehmeti, Blerim; Azizi, Bleron; Kelmendi, Jeta; Iljazi-Shahiqi, Donika; Alar, Željko; Anić-Milošević, Sandra

    2017-06-01

    An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​: Aim: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding.

  17. LAMMPS Framework for Directional Dynamic Bonding

    DEFF Research Database (Denmark)

    2012-01-01

    We have extended the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to support directional bonds and dynamic bonding. The framework supports stochastic formation of new bonds, breakage of existing bonds, and conversion between bond types. Bond formation can be controlled...... and bond types. When breaking bonds, all angular and dihedral interactions involving broken bonds are removed. The framework allows chemical reactions to be modeled, and use it to simulate a simplistic, coarse-grained DNA model. The resulting DNA dynamics illustrates the power of the present framework....... to limit the maximal functionality of a bead with respect to various bond types. Concomitant with the bond dynamics, angular and dihedral interactions are dynamically introduced between newly connected triplets and quartets of beads, where the interaction type is determined from the local pattern of bead...

  18. Optimising hydrogen bonding in solid wood

    DEFF Research Database (Denmark)

    Engelund, Emil Tang

    2009-01-01

    The chemical bonds of wood are both covalent bonds within the wood polymers and hydrogen bonds within and between the polymers. Both types of bonds are responsible for the coherence, strength and stiffness of the material. The hydrogen bonds are more easily modified by changes in load, moisture...... and temperature distorting the internal bonding state. A problem arises when studying hydrogen bonding in wood since matched wood specimens of the same species will have very different internal bonding states. Thus, possible changes in the bonding state due to some applied treatment such as conditioning...... maintaining 100 % moisture content of the wood. The hypothesis was that this would enable a fast stress relaxation as a result of reorganization of bonds, since moisture plasticizes the material and temperature promotes faster kinetics. Hereby, all past bond distortions caused by various moisture, temperature...

  19. Mars in their eyes - a cartoon exhibition

    Science.gov (United States)

    Pillinger, Pi.

    Recently a collection of 120 cartoons which tell the story of Mars exploration and scientific discovery, past, present and future, was held in London. We discuss the aims of the exhibition, to what extent we believe the original aims were met and report on additional outreach opportunities resulting from the project. The overriding aim was to capitalise on the popular appeal of accessible art - most people admit to enjoying cartoons. This was strengthened by hanging the originals of cartoons which had, mostly, been published in newspapers and magazines in a wide selection of countries. The provenances served to indicate the attraction of Mars to a wide public. We were fortunate to work with the Cartoon Art Trust of the UK who was in the process of relocating to new premises and opening as The Cartoon Museum, in the tourist area of Bloomsbury, central London, very close to the British Museum. "Mars in their Eyes" ran for 10 weeks during April to July 2006; immediately following which a selection of the cartoons was displayed at the week-long Royal Society Summer Exhibition. We explore the differences between the two exhibitions and comment on the various audience responses. We use this comparison to discuss whether a project which is primarily art can be extended to explain science. Does the coupling merely result in dumbing-down of both cultures or is there a true synergy? The experience has led us to coin the phrase "extreme outreach". Projects which are as ambitious as "Mars in their Eyes", without the security of a safe, captive audience, for example at a Science Centre, must be judged by different criteria. Indeed if the project does not meet comparable targets like large visitor numbers, then the honest evaluation of such details can only inform future activities and must not be reflected in the future funding of only "safe" outreach activities.

  20. Art Therapy Exhibitions: Exploitation or Advocacy?

    Science.gov (United States)

    Davis, Terri

    2017-01-01

    Promoting awareness of human trafficking by sharing trauma survivors' art and summaries of their life stories suggests ethical complexities that have been typically neglected by bioethicists. Although these survivors voluntarily share the objects they created during art therapy sessions, they are still at risk of harm, including further exploitation, due to their vulnerability, high rates of victim sensitivity, and the mental health consequences of their traumatic experiences. While some argue that the benefits of sublimation and art therapy for human trafficking survivors make sharing their art worth the risk, anti-trafficking organizations and supporters of such art exhibitions have responsibilities to be trauma informed. © 2017 American Medical Association. All Rights Reserved.

  1. How do exhibition visitors describe aesthetic qualities?

    DEFF Research Database (Denmark)

    Thomsen, Bente Dahl; Ravn, Anders Peter

    2007-01-01

    In this investigation, visitors to an art and design exhibition have used an interactive computer program to express the qualities they consider important for an art or design object (artefact). They have then used the program with their individually selected qualities to assess the artefacts....... In this article, we present the experiment and its results. They indicate that with such a setting it is relatively easy to reach a degree of consensus about criteria. Such an interactive program can therefore be very useful, for instance when choosing among design proposals or when selecting artefacts...

  2. Applied Gamification in Self-guided Exhibitions

    DEFF Research Database (Denmark)

    Vistisen, Peter; Selvadurai, Vashanth; Krishnasamy, Rameshnath Kala

    2018-01-01

    This paper contributes to the current understanding of applied digital gamification by providing insights from two design cases from the Danish aqua zoo, the North Sea Oceanarium, concerned with self-facilitated exhibitions. Grounded in a short review of the current state of art, we provide two...... of applied gamification research. Specifically, the cases provide insights to the challenge of on-boarding visitors into participating and using the designed products during their visit. In both cases, providing certain incentives for using the app or participating in the Instagram challenge, seemed...

  3. Topology of electron charge density for chemical bonds from valence bond theory: a probe of bonding types.

    Science.gov (United States)

    Zhang, Lixian; Ying, Fuming; Wu, Wei; Hiberty, Philippe C; Shaik, Sason

    2009-01-01

    To characterize the nature of bonding we derive the topological properties of the electron charge density of a variety of bonds based on ab initio valence bond methods. The electron density and its associated Laplacian are partitioned into covalent, ionic, and resonance components in the valence bond spirit. The analysis provides a density-based signature of bonding types and reveals, along with the classical covalent and ionic bonds, the existence of two-electron bonds in which most of the bonding arises from the covalent-ionic resonance energy, so-called charge-shift bonds. As expected, the covalent component of the Laplacian at the bond critical point is found to be largely negative for classical covalent bonds. In contrast, for charge-shift bonds, the covalent part of the Laplacian is small or positive, in agreement with the weakly attractive or repulsive character of the covalent interaction in these bonds. On the other hand, the resonance component of the Laplacian is always negative or nearly zero, and it increases in absolute value with the charge-shift character of the bond, in agreement with the decrease of kinetic energy associated with covalent-ionic mixing. A new interpretation of the topology of the total density at the bond critical point is proposed to characterize covalent, ionic, and charge-shift bonding from the density point of view.

  4. The nature of electron correlation in a dissociating bond

    Science.gov (United States)

    Hollett, Joshua W.; McKemmish, Laura K.; Gill, Peter M. W.

    2011-06-01

    We have constructed the unrestricted Hartree-Fock (UHF), restricted Hartree-Fock (RHF), and full configuration interaction (FCI) position and momentum intracules and holes for HṡṡṡH at bond lengths R from 1 to 10 bohrs. We trace the recently discovered inversion of the UHF position hole at intermediate R to over-localization of the spin-orbitals, and support this by a correlation energy component analysis. The RHF and UHF momentum holes are found to be more complicated; however their features are explained through decomposition of electron correlation effects. The UHF momentum hole is also found to invert and exhibits interesting behavior at large R. The RHF (but not UHF) and FCI momentum intracules exhibit Young-type interference patterns related to recent double photoionization experiments. Our analyses yield the most comprehensive picture to date of the behavior of the electrons during homolytic bond fission.

  5. Fully Enzymatic Membraneless Glucose|Oxygen Fuel Cell That Provides 0.275 mA cm(-2) in 5 mM Glucose, Operates in Human Physiological Solutions, and Powers Transmission of Sensing Data.

    Science.gov (United States)

    Ó Conghaile, Peter; Falk, Magnus; MacAodha, Domhnall; Yakovleva, Maria E; Gonaus, Christoph; Peterbauer, Clemens K; Gorton, Lo; Shleev, Sergey; Leech, Dónal

    2016-02-16

    Coimmobilization of pyranose dehydrogenase as an enzyme catalyst, osmium redox polymers [Os(4,4'-dimethoxy-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) or [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) as mediators, and carbon nanotube conductive scaffolds in films on graphite electrodes provides enzyme electrodes for glucose oxidation. The recombinant enzyme and a deglycosylated form, both expressed in Pichia pastoris, are investigated and compared as biocatalysts for glucose oxidation using flow injection amperometry and voltammetry. In the presence of 5 mM glucose in phosphate-buffered saline (PBS) (50 mM phosphate buffer solution, pH 7.4, with 150 mM NaCl), higher glucose oxidation current densities, 0.41 mA cm(-2), are obtained from enzyme electrodes containing the deglycosylated form of the enzyme. The optimized glucose-oxidizing anode, prepared using deglycosylated enzyme coimmobilized with [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) and carbon nanotubes, was coupled with an oxygen-reducing bilirubin oxidase on gold nanoparticle dispersed on gold electrode as a biocathode to provide a membraneless fully enzymatic fuel cell. A maximum power density of 275 μW cm(-2) is obtained in 5 mM glucose in PBS, the highest to date under these conditions, providing sufficient power to enable wireless transmission of a signal to a data logger. When tested in whole human blood and unstimulated human saliva maximum power densities of 73 and 6 μW cm(-2) are obtained for the same fuel cell configuration, respectively.

  6. Children's drawings exhibited in the Globe

    CERN Multimedia

    Elizabeth Roe

    2010-01-01

    "Draw Me A Physicist" has been a success. Members of the public visiting the exhibition in the Globe of Science and Innovation have praised the scientific and creative balance the children of neighbouring France and the Canton of Geneva have obtained through their visit to CERN.   The Draw Me a Physicist exhibition in the Globe For a six-month period 9 to 11-year olds from the Pays de Gex, Meyrin, Satigny and Vernier have been able to enjoy a balance between science and art, through drawing and defining their interpretations of a physicist. In May, eight pairs of drawings from each participating class were selected by the schools to be displayed on the second floor of the Globe. Since the images have been put up, the viewers have enjoyed the contrast between the "before" pictures of vibrant Albert Einsteins to the "after" pictures of casual people sitting in an office. The large room in the Globe has been transformed from a hollow shell int...

  7. A metafluid exhibiting strong optical magnetism.

    Science.gov (United States)

    Sheikholeslami, Sassan N; Alaeian, Hadiseh; Koh, Ai Leen; Dionne, Jennifer A

    2013-09-11

    Advances in the field of metamaterials have enabled unprecedented control of light-matter interactions. Metamaterial constituents support high-frequency electric and magnetic dipoles, which can be used as building blocks for new materials capable of negative refraction, electromagnetic cloaking, strong visible-frequency circular dichroism, and enhancing magnetic or chiral transitions in ions and molecules. While all metamaterials to date have existed in the solid-state, considerable interest has emerged in designing a colloidal metamaterial or "metafluid". Such metafluids would combine the advantages of solution-based processing with facile integration into conventional optical components. Here we demonstrate the colloidal synthesis of an isotropic metafluid that exhibits a strong magnetic response at visible frequencies. Protein-antibody interactions are used to direct the solution-phase self-assembly of discrete metamolecules comprised of silver nanoparticles tightly packed around a single dielectric core. The electric and magnetic response of individual metamolecules and the bulk metamaterial solution are directly probed with optical scattering and spectroscopy. Effective medium calculations indicate that the bulk metamaterial exhibits a negative effective permeability and a negative refractive index at modest fill factors. This metafluid can be synthesized in large-quantity and high-quality and may accelerate development of advanced nanophotonic and metamaterial devices.

  8. Radiation-related information at science exhibitions

    Energy Technology Data Exchange (ETDEWEB)

    Bannai, Tadaaki [Inst. for Environmental Sciences, Rokkasho, Aomori (Japan)

    1999-09-01

    The aim of the present report was to promote an efficient utilization of science museums providing with educational information concerning radiations. Investigations were made on radiation-related materials exhibited at 38 museums including PR event sites between April 1996 and July 1998 mainly located on Kanto and Tohoku area in Japan. The investigation concerned as to whether the displays on radiation-related material (cosmic rays, X-rays, etc) existed or not, and as to the background of the display as well. As the result, 14 locations had no relevant displays, 10 of them not having things about atomic energy at all. The locations belonging to electricity company mostly had displays related to radiations and atomic energy power generation. A spark chamber was exhibited at 9 locations and a cloud chamber at 3 locations, but only one location among them displayed both. Displays on the actual use of X-radiation were found at 4 locations. Needs to prepare further improved displays exist at the sites visited. (S. Ohno)

  9. CERN Inspires Art in Major New Exhibition

    CERN Multimedia

    2001-01-01

    Signatures of the Invisible, an exhibition inspired by CERN, opened at the Atlantis Gallery in London on Thursday, 1 March before going on a world tour. The fruit of a close collaboration between CERN and the London Institute, the exhibition brings together works from many leading European contemporary artists. White wooden boxes on a grey floor... the lids opened, unveiling brilliant white light from a bunch of optical fibres carefully stuck together in the shape of a square. Another holds a treasure of lead glass surrounded by enigmatic black mirrors. What's it all about? Signatures of the Invisible, that's what, a joint project organised by the London Institute, one of the world's largest college of art, and our Laboratory. Damien Foresy from the EST workshop putting finishing touches to the spinning tops of French artist Jérôme Basserode. Monica Sand's boxes are just one of the many works based around materials used in particle detection at CERN that was admired at the opening o...

  10. NMR Investigations of Noncovalent Carbon Tetrel Bonds. Computational Assessment and Initial Experimental Observation.

    Science.gov (United States)

    Southern, Scott A; Bryce, David L

    2015-12-10

    Group IV tetrel elements may act as tetrel bond donors, whereby a region of positive electrostatic potential (σ-hole) interacts with a Lewis base. The results of calculations of NMR parameters are reported for a series of model compounds exhibiting tetrel bonding from a methyl carbon to the oxygen or nitrogen atoms in various functional groups. The (13)C chemical shift (δiso) and the (1c)J((13)C,Y) coupling (Y = (17)O, (15)N) across the tetrel bond are recorded as a function of geometry. The sensitivity of the NMR parameters to the noncovalent interaction is demonstrated via an increase in δiso and in |(1c)J((13)C,Y)| as the tetrel bond shortens. Gauge-including projector-augmented wave density functional theory (DFT) calculations of δiso are reported for crystals that exhibit tetrel bonding in the solid state. Experimental δiso values for solid sarcosine and its tetrel-bonded salts corroborate the computational findings. This work offers new insights into tetrel bonding and facilitates the incorporation of tetrel bonds as restraints in NMR crystallographic structure refinement.

  11. "Vibrational bonding": a new type of chemical bond is discovered.

    Science.gov (United States)

    Rhodes, Christopher J; Macrae, Roderick M

    2015-01-01

    A long-sought but elusive new type of chemical bond, occurring on a minimum-free, purely repulsive potential energy surface, has recently been convincingly shown to be possible on the basis of high-level quantum-chemical calculations. This type of bond, termed a vibrational bond, forms because the total energy, including the dynamical energy of the nuclei, is lower than the total energy of the dissociated products, including their vibrational zero-point energy. For this to be the case, the ZPE of the product molecule must be very high, which is ensured by replacing a conventional hydrogen atom with its light isotope muonium (Mu, mass = 1/9 u) in the system Br-H-Br, a natural transition state in the reaction between Br and HBr. A paramagnetic species observed in the reaction Mu +Br2 has been proposed as a first experimental sighting of this species, but definitive identification remains challenging.

  12. School Bond Success: An Exploratory Case Study

    Science.gov (United States)

    Holt, Carleton R.; Wendt, Matthew A,; Smith, Roland M.

    2006-01-01

    Following two-failed school bond issues in 1995 and 1998, one mid-sized rural school district organized an effort that led to two successful school bond elections in 2001 and 2003. The school district's strategic plan mirrored many of the recommendations for successful bond referendums published in School Bond Success: A Strategy for Building…

  13. Common Factors in International Bond Returns

    NARCIS (Netherlands)

    Driessen, J.J.A.G.; Melenberg, B.; Nijman, T.E.

    2000-01-01

    In this paper we estimate and interpret the factors that jointly determine bond returns of different maturities in the US, Germany and Japan.We analyze both currency-hedged and unhedged bond returns.For currency-hedged bond returns, we find that five factors explain 96.5% of the variation of bond

  14. Pet Bonding and Pet Bereavement among Adolescents.

    Science.gov (United States)

    Brown, Brenda H.; And Others

    1996-01-01

    Studied adolescent-pet bonding and bereavement following pet loss (n=55). Hypothesized that highly-bonded adolescents experience more intense grief when a pet dies than do those less bonded; degree of bonding is greater for girls than for boys; and intensity of bereavement is greater for girls than for boys. Results supported the hypotheses. (RB)

  15. Concept of human bonding; concept of dependence

    Directory of Open Access Journals (Sweden)

    Paolo Cianconi

    2014-09-01

    Full Text Available This work explores the anthropological theme of dependence in human cultural frameworks, highlighting the usefulness of the concept of human bonding. The human bonding is seen as a function and useful tool for cross-explaining the construction, maintenance and fall of alliances within the physiological relationships between humans and between humans and objects.Keywords: Bond; Dependence; Bond quality

  16. 27 CFR 19.516 - Bond account.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bond account. 19.516... Determination and Payment of Tax § 19.516 Bond account. Where the proprietor has furnished a withdrawal or unit... maximum penal sum, he shall maintain an account of his bond and he shall charge the bond with the amount...

  17. Scientific inheritance of M. M. Lange

    Directory of Open Access Journals (Sweden)

    С. І. Яковенко

    2014-07-01

    Full Text Available Рец. на кн. : Научное наследие Н. Н. Ланге в университетской библиотеке / В. И. Подшивалкина, Р. Н. Свинаренко, Е. В. Полевщикова; авт.-сост.: М. В. Алексеенко, Е. В. Бережок, О. Л. Ляшенко, И. В. Пигулевская, Е. В. Полевщикова, Е. В. Са­вельева, В. С. Кочмар; науч. ред. В. И. Подшивалкина; отв. ред. М. А. Подрезова; библиогр. ред. В. В. Самодурова; Одес. нац. ун-т им. И. И. Мечникова. — Одесса: Астропринт, 2010. — 352 с., [8] л. ил. — (Сер. «Развитие науки в Одес­ском (Новороссийском университете; вып.: Психология».

  18. Indirect versus direct bonding--a shear bond strength comparison: an in vitro study.

    Science.gov (United States)

    Swetha, M; Pai, Vinaya S; Sanjay, N; Nandini, S

    2011-07-01

    The process of bonding orthodontic appliances to the enamel surface of the teeth has come to the forefront as a major improvement in bonding techniques. The purpose of this study is to compare the shear bond strength of stainless steel orthodontic brackets bonded using conventional direct bonding and indirect bonding as described by Thomas. Forty sound human premolars were divided into two groups of 20 each. Group I samples were bonded directly on the tooth surface using concise two paste adhesive system after etching and drying. Group II samples were bonded indirectly on the tooth surface according to Thomas indirect bonding technique using concise two paste adhesive system. The stored specimen was tested for shear bond strength in an Instron universal testing machine at a crosshead speed of 0.5 mm/minute. Data obtained were subjected to statistical analysis. The results showed that there was no statistically significant difference in the shear bond strength between direct and indirect bonding techniques. Chi-square test showed that there were significant differences among the adhesive remnant index scores between direct and indirect bonding groups. In vitro shear bond strength comparison between direct and indirect-bonded attachments showed no significant difference between the two groups. Bond strength obtained with Thomas indirect bonding technique was comparable with direct bonding technique. Thomas indirect bonding technique can be used for bonding of the posterior teeth, where the risk of moisture contamination is high during bonding.

  19. Solution and solid-state models of peptide CH...O hydrogen bonds.

    Science.gov (United States)

    Baures, Paul W; Beatty, Alicia M; Dhanasekaran, Muthu; Helfrich, Brian A; Pérez-Segarra, Waleska; Desper, John

    2002-09-25

    Fumaramide derivatives were analyzed in solution by (1)H NMR spectroscopy and in the solid state by X-ray crystallography in order to characterize the formation of CH...O interactions under each condition and to thereby serve as models for these interactions in peptide and protein structure. Solutions of fumaramides at 10 mM in CDCl(3) were titrated with DMSO-d(6), resulting in chemical shifts that moved downfield for the CH groups thought to participate in CH...O=S(CD(3))(2) hydrogen bonds concurrent with NH...O=S(CD(3))(2) hydrogen bonding. In this model, nonparticipating CH groups under the same conditions showed no significant change in chemical shifts between 0.0 and 1.0 M DMSO-d(6) and then moved upfield at higher DMSO-d(6) concentrations. At concentrations above 1.0 M DMSO-d(6), the directed CH...O=S(CD(3))(2) hydrogen bonds provide protection from random DMSO-d(6) contact and prevent the chemical shifts for participating CH groups from moving upfield beyond the original value observed in CDCl(3). X-ray crystal structures identified CH...O=C hydrogen bonds alongside intermolecular NH...O=C hydrogen bonding, a result that supports the solution (1)H NMR spectroscopy results. The solution and solid-state data therefore both provide evidence for the presence of CH...O hydrogen bonds formed concurrent with NH...O hydrogen bonding in these structures. The CH...O=C hydrogen bonds in the X-ray crystal structures are similar to those described for antiparallel beta-sheet structure observed in protein X-ray crystal structures.

  20. Enamel Bond Strength of New Universal Adhesive Bonding Agents.

    Science.gov (United States)

    McLean, D E; Meyers, E J; Guillory, V L; Vandewalle, K S

    2015-01-01

    Universal bonding agents have been introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinician's preference. The purpose of this study was to evaluate the shear bond strength (SBS) of composite to enamel using universal adhesives compared to a self-etch adhesive when applied in self-etch and etch-and-rinse modes over time. Extracted human third molars were used to create 120 enamel specimens. The specimens were ground flat and randomly divided into three groups: two universal adhesives and one self-etch adhesive. Each group was then subdivided, with half the specimens bonded in self-etch mode and half in etch-and-rinse mode. The adhesives were applied as per manufacturers' instructions, and composite was bonded using a standardized mold and cured incrementally. The groups were further divided into two subgroups with 10 specimens each. One subgroup was stored for 24 hours and the second for six months in 37°C distilled water and tested in shear. Failure mode was also determined for each specimen. A three-way analysis of variance (ANOVA) found a significant difference between groups based on bonding agent (p0.05). Clearfil SE in etch-and-rinse and self-etch modes had more mixed fractures than either universal adhesive in either mode. Etching enamel significantly increased the SBS of composite to enamel. Clearfil SE had significantly greater bond strength to enamel than either universal adhesive, which were not significantly different from each other.

  1. Three methods to measure RH bond energies

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, J. [Argonne National Lab., IL (United States); Ellison, G.B. [Univ. of Colorado, Boulder, CO (United States). Dept. of Chemistry and Biochemistry; Gutman, D. [Catholic Univ. of America, Washington, DC (United States). Dept. of Chemistry

    1993-03-21

    In this paper the authors compare and contrast three powerful methods for experimentally measuring bond energies in polyatomic molecules. The methods are: radical kinetics; gas phase acidity cycles; and photoionization mass spectroscopy. The knowledge of the values of bond energies are a basic piece of information to a chemist. Chemical reactions involve the making and breaking of chemical bonds. It has been shown that comparable bonds in polyatomic molecules, compared to the same bonds in radicals, can be significantly different. These bond energies can be measured in terms of bond dissociation energies.

  2. Application of an imaging system to a museum exhibition for developing interactive exhibitions

    Science.gov (United States)

    Miyata, Kimiyoshi; Inoue, Yuka; Takiguchi, Takahiro; Tsumura, Norimichi; Nakaguchi, Toshiya; Miyake, Yoichi

    2009-10-01

    In the National Museum of Japanese History, 215,759 artifacts are stored and used for research and exhibitions. In museums, due to the limitation of space in the galleries, a guidance system is required to satisfy visitors' needs and to enhance their understanding of the artifacts. We introduce one exhibition using imaging technology to improve visitors' understanding of a kimono (traditional Japanese clothing) exhibition. In the imaging technology introduced, one data projector, one display with touch panel interface, and magnifiers were used as exhibition tools together with a real kimono. The validity of this exhibition method was confirmed by results from a visitors' interview survey. Second, to further develop the interactive guidance system, an augmented reality system that consisted of cooperation between the projector and a digital video camera was also examined. A white paper board in the observer's hand was used as a projection screen and also as an interface to control the images projected on the board. The basic performance of the proposed system was confirmed; however continuous development was necessary for applying the system to actual exhibitions.

  3. Shape-Memory PVDF Exhibiting Switchable Piezoelectricity.

    Science.gov (United States)

    Hoeher, Robin; Raidt, Thomas; Novak, Nikola; Katzenberg, Frank; Tiller, Joerg C

    2015-12-01

    In this study, a material is designed which combines the properties of shape-memory and electroactive polymers. This is achieved by covalent cross-linking of polyvinylidene fluoride. The resulting polymer network exhibits excellent shape-memory properties with a storable strain of 200%, and fixity as well as recovery values of 100%. Programming upon rolling induces the transformation from the nonelectroactive α-phase to the piezoelectric β-phase. The highest β-phase content is found to be 83% for a programming strain of 200% affording a d33 value of -30 pm V(-1). This is in good accordance with literature known values for piezoelectric properties. Thermal triggering this material does not only result in a shape change but also renders the material nonelectroactive. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Deriving the bond pricing equation

    Directory of Open Access Journals (Sweden)

    Kožul Nataša

    2014-01-01

    Full Text Available Given the recent focus on Eurozone debt crisis and the credit rating downgrade not only of US debt, but that of other countries and many UK major banking institutions, this paper aims to explain the concept of bond yield, its different measures and bond pricing equation. Yields on capital market instruments are rarely quoted on the same basis, which makes direct comparison between different as investment choices impossible. Some debt instruments are quoted on discount basis, whilst coupon-bearing ones accrue interest differently, offer different compounding opportunities, have different coupon payment frequencies, and manage non-business day maturity dates differently. Moreover, rules governing debt vary across countries, markets and currencies, making yield calculation and comparison a rather complex issue. Thus, some fundamental concepts applicable to debt instrument yield measurement, with focus on bond equation, are presented here. In addition, bond equation expressed in annuity form and used to apply Newton-Raphson algorithm to derive true bond yield is also shown.

  5. A Traveling Exhibit of Cassini Image Science

    Science.gov (United States)

    Burns, Joseph A.; Hedman, M. M.; Tiscareno, M. S.; Ebel, D.; Mac Low, M.; Lovett, L. E.; Burns, J. K.; Schaff, N.; Bilson, E. M.

    2007-10-01

    An exhibit of Cassini's images will open at NYC's American Museum of Natural History in March 2008 and then visit the Johnson Art Museum (Cornell) throughout fall 2008, including during next year's DPS. It is under consideration by several other venues in the States and overseas. The exhibit will feature 40-50 images, ranging from letter size to large posters, taken by remote-sensing instruments aboard Cassini and Huygens. Photos will be organized into a half-dozen thematic clusters (e.g., organized by celestial target or by physical process); a panel will introduce each grouping with individual images identified briefly. The Saturn system is a perfect vehicle to educate citizens about planetary science and origins. The images’ beauty should capture the public's attention, allowing us to then engage their curiosity about the relevant science. Among the Saturn system's broad suite of objects are Enceladus and Titan, two satellites of astrobiological interest; moreover, the rings display many processes active in other astrophysical disks. Several auxiliary ideas will be implemented. In Ithaca, we will project images at night against the museum's sand-colored exterior walls. A 10-12 minute musical composition has been commissioned from Roberto Sierra to open the show. We will encourage school children to participate in a human orrery circling the museum and will seek volunteers to participate in several Saturnalia. At Cornell we will involve the university and local communities, by taping their reactions to the images’ exquisite beauty as well as to their scientific content. Cassini will be the E/PO focus of next year's DPS meeting; those materials will be employed throughout the fall at New York schools and be available to travel with the show. We intend to work with NYC partners to offer teacher credits for associated weekend courses. We will produce classroom materials, including a DVD, for teacher use.

  6. Thujone exhibits low affinity for cannabinoid receptors but fails to evoke cannabimimetic responses.

    Science.gov (United States)

    Meschler, J P; Howlett, A C

    1999-03-01

    Absinthe, an abused drug in the early 1900s, has been speculated to activate the receptors responsible for marijuana intoxication (the CB1 cannabinoid receptor) (Nature 253:365-356; 1975). To test this hypothesis, we investigated oil of wormwood (Artemisia absinthium) the active plant product found in absinthe, and thujone, the active compound found in oil of wormwood. Radioligand receptor binding assays employing membrane preparations from rat brains containing CB1 cannabinoid receptors, and human tonsils containing CB2 receptors, demonstrated that thujone displaced [3H]CP55940, a cannabinoid agonist, only at concentrations above 10 microM. HPLC analysis of oil of wormwood revealed that only the fractions having mobility close to thujone displaced [3H]CP55940 from the CB1 cannabinoid receptor. [35S]GTPgammaS binding assays revealed that thujone failed to stimulate G-proteins even at 0.1 mM. Thujone failed to inhibit forskolin-stimulated adenylate cyclase activity in N18TG2 membranes at 1 mM. Rats administered thujone exhibited different behavioral characteristics compared with rats administered a potent cannabinoid agonist, levonantradol. Therefore, the hypothesis that activation of cannabinoid receptors is responsible for the intoxicating effects of thujone is not supported by the present data.

  7. Simultaneous bond degradation and bond formation during phenol-formaldehyde curing with wood

    Science.gov (United States)

    Daniel J. Yelle; John Ralph

    2016-01-01

    Bonding of wood using phenol–formaldehyde adhesive develops highly durable bonds. Phenol– formaldehyde is believed to form primary bonds with wood cell wall polymers (e.g., lignin). However, it is unclear how this adhesive interacts and bonds to lignin. Through wood solubilisation methodologies, earlywood and latewood bonded assemblies were characterized using two-...

  8. FATHER, SOCIAL BOND AND WOMEN

    Directory of Open Access Journals (Sweden)

    SYLVIA DE CASTRO KORGI

    2006-05-01

    Full Text Available On the cross-point of two of the most important and inseparable Freudian questions: What is a father?and, What a woman wants?, this paper begins a reflection about the women’s place in the Freudianarticulation of the relationship between the father and the social bond. In fact, the Freudian father, thanksto the law mediation which he is its agent, has as a function the regulation of the pleasure that participatesin the social bond, making this way possible the human community. On the other hand, the support ofthe human community is the bond among brothers, as well as Freud presents it in his foundational textof the Law. How to precise the women’s place in this arrangement? The reflection stands out this thatexceeds the Father’s Law and that Freud sets on women’s account, initially under the figure of heropposition to the culture.

  9. Electron transfer in pnicogen bonds.

    Science.gov (United States)

    Guan, Liangyu; Mo, Yirong

    2014-10-02

    As a new type of noncovalent interactions, pnicogen bond between a VA group element (N, P, and As) and an electron donor (Lewis base) has grabbed attention in recent several years. Here we employ the block-localized wave function (BLW) based energy decomposition scheme to probe the bonding nature in a series of substituted phosphines X(n)PH(3-n) complexed with ammonia. As the BLW method can derive the optimal monomer orbitals in a complex with the electron transfer among monomers quenched, we can effectively examine the HOMO-LUMO interaction in these pnicogen bonding systems. Among various energy components, electron transfer energy together with the polarization energy dominates the pnicogen bonding energy. Although usually it is assumed that the electron transfer from ammonia to substituted phosphines occurs in the form of n → σ*(XP) hyperconjugative interaction, we identify a kind of new pathway when X = NO2 and CN, i.e., n → dπ*, which results from the interaction between the π orbital of cyano or nitro substituent and d orbitals on P. But still this picture of electron transfer using a single pair of orbitals is greatly simplified, as the electron density difference (EDD) maps corresponding to the overall electron transfer processes show the accumulation of electron density on the P side opposite to the X-P bond, with insignificant or even negligible gain of electron density on the substituent group side. Thus, the EDD maps tend to support the concept of σ-hole in pnicogen bonds.

  10. Exhibition of Stochastic Resonance in Vestibular Perception

    Science.gov (United States)

    Galvan-Garza, R. C.; Clark, T. K.; Merfeld, D. M.; Bloomberg, J. J.; Oman, C. M.; Mulavara, A. P.

    2016-01-01

    Astronauts experience sensorimotor changes during spaceflight, particularly during G-transitions. Post flight sensorimotor changes include spatial disorientation, along with postural and gait instability that may degrade operational capabilities of the astronauts and endanger the crew. A sensorimotor countermeasure that mitigates these effects would improve crewmember safety and decrease risk. The goal of this research is to investigate the potential use of stochastic vestibular stimulation (SVS) as a technology to improve sensorimotor function. We hypothesize that low levels of SVS will improve sensorimotor perception through the phenomenon of stochastic resonance (SR), when the response of a nonlinear system to a weak input signal is enhanced by the application of a particular nonzero level of noise. This study aims to advance the development of SVS as a potential countermeasure by 1) demonstrating the exhibition of stochastic resonance in vestibular perception, a vital component of sensorimotor function, 2) investigating the repeatability of SR exhibition, and 3) determining the relative contribution of the semicircular canals (SCC) and otolith (OTO) organs to vestibular perceptual SR. A constant current stimulator was used to deliver bilateral bipolar SVS via electrodes placed on each of the mastoid processes, as previously done. Vestibular perceptual motion recognition thresholds were measured using a 6-degree of freedom MOOG platform and a 150 trial 3-down/1-up staircase procedure. In the first test session, we measured vestibular perceptual thresholds in upright roll-tilt at 0.2 Hz (SCC+OTO) with SVS ranging from 0-700 µA. In a second test session a week later, we re-measured roll-tilt thresholds with 0, optimal (from test session 1), and 1500 µA SVS levels. A subset of these subjects, plus naive subjects, participated in two additional test sessions in which we measured thresholds in supine roll-rotation at 0.2 Hz (SCC) and upright y-translation at 1 Hz

  11. Analysis Of Chemical Bonding Using Ab Initio Valence Bond Theory

    NARCIS (Netherlands)

    Engelberts, J.J.

    2017-01-01

    In this thesis, theoretical chemical research is presented in which the Valence Bond (VB) Theory plays a central role. For the last three chapters, the VB method is used, in combination with Magnetically Induced Ring Currents, to analyze the aromaticity of several conjugated molecules. The

  12. Why Bond Critical Points Are Not "Bond" Critical Points.

    Science.gov (United States)

    Shahbazian, Shant

    2017-12-28

    Equating (3,-1) critical points (CPs), derived from the topological analysis of the electron densities, to chemical bonds has triggered a lot of confusion in recent years. Part of this confusion stems from calling these CPs "bond" CPs (BCPs). While the origin of this terminology is traceable to the late seventies and beginning of eighties, when it sounded reasonable, new computational studies conducted on molecular electron densities cast serious doubt on the supposed universal equivalence between the chemical bonds and (3,-1) CPs. Herein, recent computational studies are briefly reviewed to demonstrate why (3,-1) CPs are not indicators of chemical bonds. It is discussed why this confusing terminology needs to be changed and reemphasized that (3,-1) CPs should be called "line" critical points (LCPs). The proposed terminology detaches the topological properties of molecular electron densities from any a priori chemical interpretation. Such detachment, if adopted by other authors, will hopefully prevent further misinterpretation of the data emerging from the quantum theory of atoms in molecules (QTAIM). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Exhibiting Good Health: Public Health Exhibitions in London, 1948-71.

    Science.gov (United States)

    Mold, Alex

    2018-01-01

    This article examines the changing nature of public health services and their relationship with the public in post-war Britain by an analysis of the exhibitions mounted by Medical Officers of Health (MOsH) in London. Focusing on the period 1948-71, the article explores a time when public health practice, and the problems it faced, were in flux. A decline in infectious disease and an increase in chronic conditions linked to lifestyle required a new role for public health services. Exhibitions were one of several methods that MOsH used to inform the public about dangers to their health, but also to persuade them to change their behaviour. The exhibition, though, offers a unique insight into the relationship between public health authorities and the public, as exhibitions brought MOsH into direct contact with people. It is suggested that in the MOsH exhibitions we can find signs of a new relationship between public health practitioners and the public. Whilst elements of the pre-war, often moralistic ideology of public health services could still be detected, there is also evidence of a more nuanced, responsive dynamic between practitioners and the people. By the end of the 1960s, 'the public' was increasingly being thought of as a collection of 'publics', including individuals, target groups and vocal respondents.

  14. Exhibiting health and medicine as culture

    DEFF Research Database (Denmark)

    Whiteley, Louise; Tybjerg, Karin; Pedersen, Bente Vinge

    2017-01-01

    Introduction: This paper discusses the potential role of medical museums in public engagement with health and medicine, based on the work of Medical Museion at the University of Copenhagen. Rather than asking whether cultural venues such as museums can directly improve the well-being of their vis......Introduction: This paper discusses the potential role of medical museums in public engagement with health and medicine, based on the work of Medical Museion at the University of Copenhagen. Rather than asking whether cultural venues such as museums can directly improve the well......-being of their visitors, we instead focus on how museums should communicate about health and medicine. Methods: The paper describes three examples of exhibitions at Medical Museion that attempt to display medicine as culture, and draws out three of the key strategies they employ. Results: The three key strategies are: (1......: There is increasing emphasis on the need for health communication to recognize people’s multiple, lived cultures. We argue that we should also recognize that medical research and practice is itself a form of culture, and as such is multiple and historically shifting. This paper demonstrates that museums are an ideal...

  15. Agitated honeybees exhibit pessimistic cognitive biases.

    Science.gov (United States)

    Bateson, Melissa; Desire, Suzanne; Gartside, Sarah E; Wright, Geraldine A

    2011-06-21

    Whether animals experience human-like emotions is controversial and of immense societal concern [1-3]. Because animals cannot provide subjective reports of how they feel, emotional state can only be inferred using physiological, cognitive, and behavioral measures [4-8]. In humans, negative feelings are reliably correlated with pessimistic cognitive biases, defined as the increased expectation of bad outcomes [9-11]. Recently, mammals [12-16] and birds [17-20] with poor welfare have also been found to display pessimistic-like decision making, but cognitive biases have not thus far been explored in invertebrates. Here, we ask whether honeybees display a pessimistic cognitive bias when they are subjected to an anxiety-like state induced by vigorous shaking designed to simulate a predatory attack. We show for the first time that agitated bees are more likely to classify ambiguous stimuli as predicting punishment. Shaken bees also have lower levels of hemolymph dopamine, octopamine, and serotonin. In demonstrating state-dependent modulation of categorization in bees, and thereby a cognitive component of emotion, we show that the bees' response to a negatively valenced event has more in common with that of vertebrates than previously thought. This finding reinforces the use of cognitive bias as a measure of negative emotional states across species and suggests that honeybees could be regarded as exhibiting emotions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Gastric schwannoma exhibiting increased fluorodeoxyglucose uptake.

    Science.gov (United States)

    Komatsu, Daisuke; Koide, Naohiko; Hiraga, Risako; Furuya, Naoyuki; Akamatsu, Taiji; Uehara, Takeshi; Miyagawa, Shinichi

    2009-01-01

    This is the first case of gastric schwannoma that exhibited increased accumulation of [(18)F] fluorodeoxyglucose (FDG) on positron emission tomography (PET) imaging. The patient was a 60-year-old woman in whom esophagogastroduodenoscopy showed a submucosal tumor, about 25 mm in size, in the upper body of the stomach, with ulceration at the top of the tumor. Endoscopic ultrasonography revealed a well-defined hypoechoic mass located in the proper muscle layer of the stomach. The specimen taken from the tumor showed only inflammatory degenerative tissue. Abdominal computed tomography revealed a tumor in the upper body of the stomach. FDG-PET showed FDG uptake (standardized uptake value [SUV] max 5.8) coincident with the tumor. Hence, the tumor was diagnosed initially as a gastrointestinal stromal tumor of the stomach. Laparoscopic partial gastrectomy was performed. Pathological examination showed that the tumor consisted of spindle cells with large nuclei, and mitosis was absent. The Ki-67 labeling index of the tumor cells was 4%. Immunohistochemically, the tumor cells showed a positive reaction for S-100 protein, whereas they were negative for KIT, CD 34, and alpha-smooth muscle actin protein. The tumor was diagnosed as a benign gastric schwannoma. Gastric schwannoma should be included in the differential diagnosis of submucosal tumors of the stomach with FDG uptake.

  17. A second order thermodynamic perturbation theory for hydrogen bond cooperativity in water

    OpenAIRE

    Marshall, Bennett D.

    2017-01-01

    It has been extensively demonstrated through first principles quantum mechanics calculations that water exhibits strong hydrogen bond cooperativity. Classical molecular simulation and statistical mechanics methods typically assume pairwise additivity, meaning they cannot account for these 3-body and higher cooperative effects. In this document, we extend second order thermodynamic perturbation theory to correct for hydrogen bond cooperativity in 4 site water. We show that the association theo...

  18. Preparation and properties of isotropic Nd-Fe-B bonded magnets with sodium silicate binder

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.Q.; Hu, R.J.; Yue, M., E-mail: yueming@bjut.edu.cn; Yin, Y.X.; Zhang, D.T.

    2017-08-01

    Graphical abstract: To improve the working temperature of bonded Nd-Fe-B magnets, the heat-resistant binder, sodium silicate, was used to prepare new type bonded Nd-Fe-B magnets. The three-dimensional Si-O-Si structure formed in the curing process has excellent strength; it can ensure that the bonded magnets have a certain shape and usable magnetic properties when working at 200 °C. - Highlights: • Sodium silicate enables bonded Nd-Fe-B magnets to be used for higher operation temperatures. • The sodium silicate bonded magnets exhibit usable maximum energy product of 4.057 MGOe at 200 °C. • The compressive strength of sodium silicate bonded magnets is twice bigger than that of epoxy resin bonded magnets. - Abstract: In present study, sodium silicate, a kind of heat-resistant binder, was used to prepare bonded Nd-Fe-B magnets with improved thermal stability and mechanical strength. Effect of curing temperature and curing time of the new binder to the magnetic properties, microstructure, and mechanical strength of the magnets was systematically investigated. Fracture surface morphology observation show that sodium silicate in bonded magnets could completely be cured at 175 °C for 40 min, and the magnets prepared under this condition exhibit optimal properties. They exhibit usable magnetic properties of B{sub r} of 4.66 kGs, H{sub cj} of 4.84 kOe, and (BH){sub max} of 4.06 MGOe at 200 °C. Moreover, the magnets possess high compressive strength of 63 MPa.

  19. Effectiveness of immediate bonding of etch-and-rinse adhesives to simplified ethanol-saturated dentin.

    Science.gov (United States)

    Guimarães, Leandro Afonso; Almeida, Júlio César Franco; Wang, Linda; D'Alpino, Paulo Henrique Perlatti; Garcia, Fernanda Cristina Pimentel

    2012-01-01

    This study examined the immediate bond strength of etch-and-rinse adhesives to demineralized dentin saturated with either water or absolute ethanol. The research hypothesis was that there would be no difference in bond strength to dentin between water or ethanol wet-bonding techniques. The medium dentin of 20 third molars was exposed (n = 5). The dentin surface was then acid-etched, left moist and randomly assigned to be saturated via either water wet-bonding (WBT) or absolute ethanol wet-bonding (EBT). The specimens were then treated with one of the following etch-and-rinse adhesive systems: a 3-step, water-based system (Adper Scotchbond Multipurpose, or SBMP) or a 2-step, ethanol/water-based system (Adper Single Bond 2, or SB). Resin composite build-ups were then incrementally constructed. After water storage for 24 h at 37°C, the tensile strength of the specimens was tested in a universal testing machine (0.5 mm/min). Data were analyzed by two-way ANOVA and Tukey's test (a = 5%). The failure modes were verified using a stereomicroscope (40'). For both adhesives, no significant difference in bond strength was observed between WBT and EBT (p > 0.05). The highest bond strength was observed for SB, regardless of the bonding technique (p adhesives and bonding techniques was noticed (p = 0.597). There was a predominance of adhesive failures for all tested groups. The EBT and WBT displayed similar immediate bond strength means for both adhesives. The SB adhesive exhibited higher means for all conditions tested. Further investigations are needed to evaluate long-term bonding to dentin mediated by commercial etch-and-rinse adhesives using the EBT approach.

  20. Effectiveness of immediate bonding of etch-and-rinse adhesives to simplified ethanol-saturated dentin

    Directory of Open Access Journals (Sweden)

    Leandro Afonso Guimarães

    2012-04-01

    Full Text Available This study examined the immediate bond strength of etch-and-rinse adhesives to demineralized dentin saturated with either water or absolute ethanol. The research hypothesis was that there would be no difference in bond strength to dentin between water or ethanol wet-bonding techniques. The medium dentin of 20 third molars was exposed (n = 5. The dentin surface was then acid-etched, left moist and randomly assigned to be saturated via either water wet-bonding (WBT or absolute ethanol wet-bonding (EBT. The specimens were then treated with one of the following etch-and-rinse adhesive systems: a 3-step, water-based system (Adper Scotchbond Multipurpose, or SBMP or a 2-step, ethanol/water-based system (Adper Single Bond 2, or SB. Resin composite build-ups were then incrementally constructed. After water storage for 24 h at 37°C, the tensile strength of the specimens was tested in a universal testing machine (0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey's test (a = 5%. The failure modes were verified using a stereomicroscope (40'. For both adhesives, no significant difference in bond strength was observed between WBT and EBT (p > 0.05. The highest bond strength was observed for SB, regardless of the bonding technique (p < 0.05. No significant interaction between adhesives and bonding techniques was noticed (p = 0.597. There was a predominance of adhesive failures for all tested groups. The EBT and WBT displayed similar immediate bond strength means for both adhesives. The SB adhesive exhibited higher means for all conditions tested. Further investigations are needed to evaluate long-term bonding to dentin mediated by commercial etch-and-rinse adhesives using the EBT approach.

  1. Effects of direct and indirect bonding techniques on bond strength and microleakage after thermocycling

    National Research Council Canada - National Science Library

    Fırat, Öztürk; Babacan, Hasan; Nalçacı, Ruhi; Kuştarcı, Alper

    2009-01-01

    The purpose of this study was to compare the shear bond strength (SBS) of brackets and microleakage of a tooth-adhesive-bracket complex bonded with a direct and an indirect bonding technique after thermocycling...

  2. 76 FR 14746 - Surety Companies Acceptable on Federal Bonds Change in State of Incorporation; Western Bonding...

    Science.gov (United States)

    2011-03-17

    ... Fiscal Service Surety Companies Acceptable on Federal Bonds Change in State of Incorporation; Western Bonding Company; Western Insurance Company AGENCY: Financial Management Service, Fiscal Service... Bonding Company (NAIC 13191) and Western Insurance Company (NAIC 10008) have redomesticated from the state...

  3. Polymer Bonding of Optical Fibers

    Science.gov (United States)

    Goss, W.; Nelson, M. D.

    1983-01-01

    Optical waveguies coupled through their sides. In fiber etching process bonded length for coupling determined by observing optical output powers in two fibers. Surface tension of etchant remaining between two fibes holds then in contact when raised from solution for power measurement. When fibers reimmersed, they separate allowing free access by etchant.

  4. Successful bonding in orthodontics: 1.

    Science.gov (United States)

    Turner, P J

    1996-11-01

    Since it was first described in 1955, direct bonding of orthodontic attachments to the teeth has become routine in fixed appliance therapy. The technique used is deceptively simple: meticulous attention to detail and a thorough understanding of the factors involved are needed to ensure a successful outcome.

  5. Bonded repairs for aircraft fuselages

    OpenAIRE

    Vlot, A.; Verhoeven, S.; Nijssen, P.J.M.

    1998-01-01

    This report will give an overview of the bonded repair work that has been done over the last few years by the Faculty of Aerospace Engineering of Delft University of Technology, in cooperation with the Center for Aircraft Structural Life Extension at the United States Air Force Academy in Colorado Springs.

  6. Bonded repairs for aircraft fuselages

    NARCIS (Netherlands)

    Vlot, A.; Verhoeven, S.; Nijssen, P.J.M.

    1998-01-01

    This report will give an overview of the bonded repair work that has been done over the last few years by the Faculty of Aerospace Engineering of Delft University of Technology, in cooperation with the Center for Aircraft Structural Life Extension at the United States Air Force Academy in Colorado

  7. Essays on European bond markets

    NARCIS (Netherlands)

    Cheung, Y.C.

    2005-01-01

    This dissertation focused on a number of issues that are of importance in the current European bond market. In the past years, the fiscal policy of the Eurozone members, advances in the technology of trading platforms and the introduction of a single currency have reshaped the fixed income markets

  8. Breaking Rules–Making Bonds

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 1. Breaking Rules - Making Bonds. A G Samuelson. General Article Volume 21 Issue 1 January 2016 pp 43-48. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/021/01/0043-0048. Keywords.

  9. Adhesive bonding of wood materials

    Science.gov (United States)

    Charles B. Vick

    1999-01-01

    Adhesive bonding of wood components has played an essential role in the development and growth of the forest products industry and has been a key factor in the efficient utilization of our timber resource. The largest use of adhesives is in the construction industry. By far, the largest amounts of adhesives are used to manufacture building materials, such as plywood,...

  10. Weld bonding of stainless steel

    DEFF Research Database (Denmark)

    Santos, I. O.; Zhang, Wenqi; Goncalves, V.M.

    2004-01-01

    This paper presents a comprehensive theoretical and experimental investigation of the weld bonding process with the purpose of evaluating its relative performance in case of joining stainless steel parts, against alternative solutions based on structural adhesives or conventional spot-welding. Th...

  11. dimensional architectures via hydrogen bonds

    Indian Academy of Sciences (India)

    Administrator

    dimensional architectures via hydrogen bonds. LALIT RAJPUT, MADHUSHREE SARKAR and KUMAR BIRADHA*. Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302 e-mail: kbiradha@chem.iitkgp.ernet.in. Abstract. The reactions of bis(pyridylcarboxamido)alkanes (amides) and bis(3-pyridyl) ...

  12. Bonded polyimide fuel cell package

    Science.gov (United States)

    Morse, Jeffrey D.; Jankowski, Alan; Graff, Robert T.; Bettencourt, Kerry

    2010-06-08

    Described herein are processes for fabricating microfluidic fuel cell systems with embedded components in which micron-scale features are formed by bonding layers of DuPont Kapton.TM. polyimide laminate. A microfluidic fuel cell system fabricated using this process is also described.

  13. Evaluation of an alternative technique to optimize direct bonding of orthodontic brackets to temporary crowns

    Directory of Open Access Journals (Sweden)

    Francilena Maria Campos Santos Dias

    2015-08-01

    Full Text Available OBJECTIVE: To compare shear bond strength of different direct bonding techniques of orthodontic brackets to acrylic resin surfaces.METHODS: The sample comprised 64 discs of chemically activated acrylic resin (CAAR randomly divided into four groups: discs in group 1 were bonded by means of light-cured composite resin (conventional adhesive; discs in group 2 had surfaces roughened with a diamond bur followed by conventional direct bonding by means of light-cured composite resin; discs in group 3 were bonded by means of CAAR (alternative adhesive; and discs in group 4 had surfaces roughened with a diamond bur followed by direct bonding by means of CAAR. Shear bond strength values were determined after 24 hours by means of a universal testing machine at a speed of 0.5 mm/min, and compared by analysis of variance followed by post-hoc Tukey test. Adhesive remnant index (ARI was measured and compared among groups by means of Kruskal-Wallis and Dunn tests.RESULTS: Groups 3 and 4 had significantly greater shear bond strength values in comparison to groups 1 and 2. Groups 3 and 4 yielded similar results. Group 2 showed better results when compared to group 1. In ARI analyses, groups 1 and 2 predominantly exhibited a score equal to 0, whereas groups 3 and 4 predominantly exhibited a score equal to 3.CONCLUSIONS: Direct bonding of brackets to acrylic resin surfaces using CAAR yielded better results than light-cured composite resin. Surface preparation with diamond bur only increased shear bond strength in group 2.

  14. The corrosion behaviour of uncoated bonded NdFeB magnets in humid environments

    Science.gov (United States)

    Tattam, C.; Williams, A. J.; Hay, J. N.; Harris, I. R.; Tedstone, S. F.; Ashraf, M. M.

    1996-01-01

    The corrosion behaviour of uncoated bonded NdFeB magnets prepared using different binders has been assessed in a humid environment (100°C, saturated water vapour) by means of mass change measurements and magnetic characterisation. Epoxy resin, zinc and polytetrafluoroethylene (PTFE) have been used to bond melt spun ribbon, MQP-D, as supplied by General Motors. It has been found that the PTFE bonded samples which had been heat treated prior to testing exhibit superior corrosion resistance to the other samples, as characterised by a smaller mass change and greater retention of magnetic properties.

  15. 77 FR 18295 - Culturally Significant Objects Imported for Exhibition

    Science.gov (United States)

    2012-03-27

    ... Culturally Significant Objects Imported for Exhibition Determinations: ``Roy Lichtenstein: A Retrospective... determine that the objects to be included in the exhibition ``Roy Lichtenstein: A Retrospective'' imported from abroad for temporary exhibition within the United States, are of cultural significance. The...

  16. Bond strength of self-adhesive resin cements to tooth structure.

    Science.gov (United States)

    Hattar, Susan; Hatamleh, Muhanad M; Sawair, Faleh; Al-Rabab'ah, Mohammad

    2015-04-01

    The aim of this study was to evaluate the strength of the bond between newly introduced self-adhesive resin cements and tooth structures (i.e., enamel and dentin). Three self-adhesive cements (SmartCem2, RelyX Unicem, seT SDI) were tested. Cylindrical-shaped cement specimens (diameter, 3 mm; height, 3 mm) were bonded to enamel and dentin. Test specimens were incubated at 37 °C for 24 h. The shear bond strength (SBS) was tested in a Zwick Roll testing machine. Results were analyzed by one-way ANOVA and t-test. Statistically significant differences were defined at the α = 0.05 level. Bond failures were categorized as adhesive, cohesive, or mixed. The SBS values ranged from 3.76 to 6.81 MPa for cements bonded to enamel and from 4.48 to 5.94 MPa for cements bonded to dentin (p > 0.05 between surfaces). There were no statistically significant differences between the SBS values to enamel versus dentin for any given cement type. All cements exhibited adhesive failure at the resin/tooth interface. Regardless of their clinical simplicity, the self-adhesive resin cements examined in this study exhibit limited bond performance to tooth structures; therefore, these cements must be used with caution.

  17. THE CRM-BASED DIGITAL EXHIBITION SYSTEM FOR CLOTHING INDUSTRY

    National Research Council Canada - National Science Library

    Ming-Kuen Chen; Kuo-Hsuan Chen; Chia-Hon Chen

    2014-01-01

    .... Digital exhibition precludes the restrictions of time, location, space and planning on past physical exhibitions, and can demonstrate characteristics of diversity, interaction and low cost, and break...

  18. A 15-month evaluation of bond failures of orthodontic brackets bonded with direct versus indirect bonding technique: a clinical trial

    OpenAIRE

    Menini, Anna; Cozzani, Mauro; Sfondrini, Maria Francesca; Scribante, Andrea; Cozzani, Paolo; Gandini, Paola

    2014-01-01

    Background The purpose of this clinical longitudinal study was to investigate the effectiveness of indirect bonding technique evaluating the number of bond failures which occurred during treatment. Methods Fifty-two patients were selected and divided into two groups: group A (33 patients) bonded with the direct technique and group B (19 patients) bonded with the indirect technique. The number and date of bracket failure were recorded for over 15?months. Moreover, also the effect of crowding l...

  19. Strength of Bond Covenants and Bond Assessment Framework

    Directory of Open Access Journals (Sweden)

    Noel Yahanpath

    2012-06-01

    Full Text Available We examine bond covenants of 29 New Zealand bond issues between 2001 and 2007.Results from the study indicate that protection provided for bondholders is weak and limited.On average, only 2-3 types of covenants are embedded with the issues and only 27% of thesecovenants provide full protection to the bondholders. However, bondholders are not compensated for taking the additional risk. We propose an alternative assessment framework that directly assesses the level of protection offered to bondholders. We calculate thecovenant quality score for the issues and classify them into four levels of protection: very high protection, moderate, low and very low. Recent legislative changes will go some way towards improving investor protection and confidence, but the effect is yet to be seen. This proposed scoring framework can be used by potential investors to complement the traditional credit ratings when making their investment decisions.

  20. Chemical Bonding Technology: Direct Investigation of Interfacial Bonds

    Science.gov (United States)

    Koenig, J. L.; Boerio, F. J.; Plueddemann, E. P.; Miller, J.; Willis, P. B.; Cuddihy, E. F.

    1986-01-01

    This is the third Flat-Plate Solar Array (FSA) Project document reporting on chemical bonding technology for terrestrial photovoltaic (PV) modules. The impetus for this work originated in the late 1970s when PV modules employing silicone encapsulation materials were undergoing delamination during outdoor exposure. At that time, manufacturers were not employing adhesion promoters and, hence, module interfaces in common with the silicone materials were only in physical contact and therefore easily prone to separation if, for example, water were to penetrate to the interfaces. Delamination with silicone materials virtually vanished when adhesion promoters, recommended by silicone manufacturers, were used. The activities related to the direct investigation of chemically bonded interfaces are described.

  1. Halogen light versus LED for bracket bonding: shear bond strength.

    Science.gov (United States)

    Carvalho, Paulo Eduardo Guedes; dos Santos, Valdemir Muzulon; Isber, Hassan; Cotrim-Ferreira, Flávio Augusto

    2013-02-15

    LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus) and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE). Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.

  2. ADHESIVE SYSTEM AFFECTS REPAIR BOND STRENGTH OF RESIN COMPOSITE

    Directory of Open Access Journals (Sweden)

    Özgür IRMAK

    2017-10-01

    Full Text Available Purpose: This study evaluated the effects of different adhesive systems on repair bond strength of aged resin composites. Materials and Methods: Ninety composite discs were built and half of them were subjected to thermal aging. Aged and non-aged specimens were repaired with resin composite using three different adhesive systems; a two-step self-etch adhesive, a two-step total-etch adhesive and a one-step self-etch adhesive; then they were subjected to shear forces. Data were analyzed statistically. Results: Adhesive type and aging significantly affected the repair bond strengths (p<0.0001. No statistical difference was found in aged composite groups repaired with two-step self- etch or two-step total-etch adhesive. One-step self-etch adhesive showed lower bond strength values in aged composite repair (p<0.0001. Conclusion: In the repair of aged resin composite, two-step self-etch and two-step total-etch adhesives exhibited higher shear bond strength values than that of one-step self-etch adhesive.

  3. Cooperativity in Surface Bonding and Hydrogen Bonding of Water and Hydroxyl at Metal Surfaces

    DEFF Research Database (Denmark)

    Schiros, T.; Ogasawara, H.; Naslund, L. A.

    2010-01-01

    of the mixed phase at metal surfaces. The surface bonding can be considered to be similar to accepting a hydrogen bond, and we can thereby apply general cooperativity rules developed for hydrogen-bonded systems. This provides a simple understanding of why water molecules become more strongly bonded......We examine the balance of surface bonding and hydrogen bonding in the mixed OH + H2O overlayer on Pt(111), Cu(111), and Cu(110) via density functional theory calculations. We find that there is a cooperativity effect between surface bonding and hydrogen bonding that underlies the stability...... to the surface upon hydrogen bonding to OH and why the OH surface bonding is instead weakened through hydrogen bonding to water. We extend the application of this simple model to other observed cooperativity effects for pure water adsorption systems and H3O+ on metal surfaces....

  4. Changes in mitochondrial carriers exhibit stress-specific signatures in INS-1Eβ-cells exposed to glucose versus fatty acids.

    Directory of Open Access Journals (Sweden)

    Thierry Brun

    Full Text Available Chronic exposure of β-cells to metabolic stresses impairs their function and potentially induces apoptosis. Mitochondria play a central role in coupling glucose metabolism to insulin secretion. However, little is known on mitochondrial responses to specific stresses; i.e. low versus high glucose, saturated versus unsaturated fatty acids, or oxidative stress. INS-1E cells were exposed for 3 days to 5.6 mM glucose, 25 mM glucose, 0.4 mM palmitate, and 0.4 mM oleate. Culture at standard 11.1 mM glucose served as no-stress control and transient oxidative stress (200 µM H2O2 for 10 min at day 0 served as positive stressful condition. Mito-array analyzed transcripts of 60 mitochondrion-associated genes with special focus on members of the Slc25 family. Transcripts of interest were evaluated at the protein level by immunoblotting. Bioinformatics analyzed the expression profiles to delineate comprehensive networks. Chronic exposure to the different metabolic stresses impaired glucose-stimulated insulin secretion; revealing glucotoxicity and lipo-dysfunction. Both saturated and unsaturated fatty acids increased expression of the carnitine/acylcarnitine carrier CAC, whereas the citrate carrier CIC and energy sensor SIRT1 were specifically upregulated by palmitate and oleate, respectively. High glucose upregulated CIC, the dicarboxylate carrier DIC and glutamate carrier GC1. Conversely, it reduced expression of energy sensors (AMPK, SIRT1, SIRT4, metabolic genes, transcription factor PDX1, and anti-apoptotic Bcl2. This was associated with caspase-3 cleavage and cell death. Expression levels of GC1 and SIRT4 exhibited positive and negative glucose dose-response, respectively. Expression profiles of energy sensors and mitochondrial carriers were selectively modified by the different conditions, exhibiting stress-specific signatures.

  5. G. N. Lewis and the Chemical Bond.

    Science.gov (United States)

    Pauling, Linus

    1984-01-01

    Discusses the contributions of G. N. Lewis to chemistry, focusing on his formulation of the basic principle of the chemical bond--the idea that the chemical bond consists of a pair of electrons held jointly by two atoms. (JN)

  6. Clarifying Chemical Bonding. Overcoming Our Misconceptions.

    Science.gov (United States)

    Hapkiewicz, Annis

    1991-01-01

    Demonstrations to help students change their misconceptions about chemical bond breaking are presented. Students' misconceptions about chemical bonds in both biological and chemical systems are discussed. A calculation for the release of energy from respiration is presented. (KR)

  7. Analysis of "Kiss" Bonds Between Composite Laminates

    Science.gov (United States)

    Poveromo, Scott L.; Earthman, James C.

    2014-06-01

    One of the leading challenges to designing lightweight, cost-effective bonded structures is to detect low shear strength "kiss" bonds where no other defects such as voids and cracks exist. To develop a nondestructive testing method that is sensitive to kiss bonds, standards need to be fabricated with known strength values. In the current work, we attempt to create kiss bonds in between carbon fiber composite laminates that have been bonded with epoxy film adhesive and epoxy paste adhesive. Based on ultrasonic testing, when creating true kiss bonds using film adhesives, a complete disbond could not be avoided because of thermally induced stresses during the high-temperature cure. However, further work demonstrated that kiss bonds can be formed using room-temperature curable epoxy paste adhesives by creating an amine blush on the epoxy surface or applying a release agent on the bonding surfaces.

  8. Do matrix metalloproteinase inhibitors improve the bond durability of universal dental adhesives?

    Science.gov (United States)

    Tekçe, Neslihan; Tuncer, Safa; Demirci, Mustafa; Balci, Sibel

    2016-11-01

    The aim of this study was to evaluate the effects of matrix metalloproteinases (MMPs) inhibitors on the microtensile bond strength (μTBS) and the adhesive-dentin interface of two universal dentin bonding agents, Single Bond Universal and All Bond Universal, after 12 months of water storage. Seventy extracted, caries-free, human third molars were used in this study. Of these, 50 were used for μTBS testing and 20 were used for scanning electron microscopy. The two bonding agents were applied to flat dentin surfaces in five different ways: self-etch mode, etch-and-rinse mode with 37% phosphoric acid, etch-and-rinse mode with phosphoric acid containing 1% benzalkonium chloride, etch-and-rinse mode with phosphoric acid and 2% chlorhexidine, and etch-and-rinse mode with 0.5 M ethylenediaminetetraacetic acid (EDTA) (n = 5 for each bonding agent in each group; N = 50). Half the specimens were subjected to μTBS tests at 24 h, while half were subjected to the tests after 12 months of water storage. For each bonding agent, inhibition, storage, and their interaction effects were tested by two-way analysis of variance and Bonferroni tests. For Single Bond Universal, the benzalkonium chloride (p = 0.024) and chlorhexidine groups (p = 0.033) exhibited significantly higher μTBS values at 24 h compared with the self-etch group. For All Bond Universal, all groups displayed similar bond strengths at 24 h (p > 0.05). After 12 months of water storage, the μTBS values decreased significantly in the benzalkonium chloride group for Single Bond Universal (p = 0.001) and the self-etch (p = 0.029), chlorhexidine (p = 0.046), and EDTA (p = 0.032) groups for All Bond Universal. These results suggest that the immediate dentin bond strength increases when universal bonding systems are applied in the etch-and-rinse mode, although the durability decreases. The use of chlorhexidine and EDTA can increase the bond durability of mild adhesives such as

  9. Foreign Participation in Local Currency Bond Markets

    OpenAIRE

    John D. Burger; Francis E. Warnock

    2006-01-01

    We analyze the development of, and foreign participation in, 49 local bond markets. Countries with stable inflation rates and strong creditor rights have more developed local bond markets and rely less on foreign-currency-denominated bonds. Less developed bond markets have returns characterized by high variance and negative skewness, factors eschewed by U.S. investors. Results based on a three-moment CAPM indicate, however, that it is diversifiable idiosyncratic risk that U.S. investors appea...

  10. Diffusion bonding of Stratapax for drill bits

    Energy Technology Data Exchange (ETDEWEB)

    Middleton, J.N.; Finger, J.T.

    1983-01-01

    A process has been developed for the diffusion bonding of General Electric's Stratapax drill blanks to support studs for cutter assemblies in drill bits. The diffusion bonding process is described and bond strength test data are provided for a variety of materials. The extensive process details, provided in the Appendices, should be sufficient to enable others to successfully build diffusion-bonded drill bit cutter assemblies.

  11. Mie resonances and bonding in photonic crystals

    OpenAIRE

    Antonoyiannakis, M. I.; Pendry, J. B.

    1997-01-01

    Isolated dielectric spheres support resonant electromagnetic modes which are analogous to electronic orbitals and, like their electronic counterparts, can form bonding or anti-bonding interactions between neighbouring spheres. By irradiating the system with light at the bonding frequency an attractive interaction is induced between the spheres. We suggest that by judicious selection of bonding states we can drive a system towards a desired structure, rather than rely on the structure dictated...

  12. The private premium in public bonds

    OpenAIRE

    Anna Kovner; Chenyang Wei

    2012-01-01

    This paper is the first to document the presence of a private premium in public bonds. We find that spreads are 31 basis points higher for public bonds of private companies than for bonds of public companies, even after controlling for observable differences, including rating, financial performance, industry, bond characteristics and issuance timing. The estimated private premium increases to 40-50 basis points when a propensity matching methodology is used or when we control for fixed issuer...

  13. Assessing Bond Market Integration in Asia

    OpenAIRE

    Ip-wing Yu; Laurence Fung; Chi-sang Tam

    2007-01-01

    Development of the local bond markets has been a top priority for financial reforms in the region after the Asian financial crisis. Various initiatives have also been taken to foster the development of the regional bond market. This paper looks into the degree of integration of sovereign (government) bond markets in Asia. It provides a survey of indicators and measures to monitor the development, measure progress and assess the state of bond market integration in the region. Our empirical res...

  14. Effect of indirect composite treatment microtensile bond strength of self-adhesive resin cements.

    Science.gov (United States)

    Fuentes, María-Victoria; Escribano, Nuria; Baracco, Bruno; Romero, Martin; Ceballos, Laura

    2016-02-01

    No specific indications about the pre-treatment of indirect composite restorations is provided by the manufacturers of most self-adhesive resin cements. The potential effect of silane treatment to the bond strength of the complete tooth/indirect restoration complex is not available.The aim of this study was to determine the contribution of different surface treatments on microtensile bond strength of composite overlays to dentin using several self-adhesive resin cements and a total-etch one. Composite overlays were fabricated and bonding surfaces were airborne-particle abraded and randomly assigned to two different surface treatments: no treatment or silane application (RelyX Ceramic Primer) followed by an adhesive (Adper Scotchbond 1 XT). Composite overlays were luted to flat dentin surfaces using the following self-adhesive resin cements: RelyX Unicem, G-Cem, Speedcem, Maxcem Elite or Smartcem2, and the total-etch resin cement RelyX ARC. After 24 h, bonded specimens were cut into sticks 1 mm thick and stressed in tension until failure. Two-way ANOVA and SNK tests were applied at α=0.05. Bond strength values were significantly influenced by the resin cement used (pcement applied and surface treatment did not significantly affect dentin bond strength (p>0.05). All self-adhesive resin cements showed lower bond strength values than the total-etch RelyX ARC. Among self-adhesive resin cements, RelyX Unicem and G-Cem attained statistically higher bond strength values. Smartcem2 and Maxcem Elite exhibited 80-90% of pre-test failures. The silane and adhesive application after indirect resin composite sandblasting did not improve the bond strength of dentin-composite overlay complex. Selection of the resin cement seems to be a more relevant factor when bonding indirect composites to dentin than its surface treatment. Bond strength, self-adhesive cement, silane, dentin, indirect composite.

  15. Doubly ionic hydrogen bond interactions within the choline chloride-urea deep eutectic solvent.

    Science.gov (United States)

    Ashworth, Claire R; Matthews, Richard P; Welton, Tom; Hunt, Patricia A

    2016-07-21

    Deep eutectic solvents (DESs) are exemplars of systems with the ability to form neutral, ionic and doubly ionic H-bonds. Herein, the pairwise interactions of the constituent components of the choline chloride-urea DES are examined. Evidence is found for a tripodal CHCl doubly ionic H-bond motif. Moreover it is found that the covalency of doubly ionic H-bonds can be greater than, or comparable with, neutral and ionic examples. In contrast to many traditional solvents, an "alphabet soup" of many different types of H-bond (OHO[double bond, length as m-dash]C, NHO[double bond, length as m-dash]C, OHCl, NHCl, OHNH, CHCl, CHO[double bond, length as m-dash]C, NHOH and NHNH) can form. These H-bonds exhibit substantial flexibility in terms of number and strength. It is anticipated that H-bonding will have a significant impact on the entropy of the system and thus could play an important role in the formation of the eutectic. The 2 : 1 urea : choline-chloride eutectic point of this DES is often associated with the formation of a [Cl(urea)2](-) complexed anion. However, urea is found to form a H-bonded urea[choline](+) complexed cation that is energetically competitive with [Cl(urea)2](-). The negative charge on [Cl(urea)2](-) is found to remain localised on the chloride, moreover, the urea[choline](+) complexed cation forms the strongest H-bond studied here. Thus, there is potential to consider a urea[choline](+)·urea[Cl](-) interaction.

  16. Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding

    Science.gov (United States)

    Li, Rui; Zhou, Hui; Wei, Wei; Wang, Chen; Sun, Ying Chun; Gao, Ping

    2015-01-01

    The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilyl)ethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future. PMID:26066349

  17. Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding.

    Directory of Open Access Journals (Sweden)

    Rui Li

    Full Text Available The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilylethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future.

  18. Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding.

    Science.gov (United States)

    Li, Rui; Zhou, Hui; Wei, Wei; Wang, Chen; Sun, Ying Chun; Gao, Ping

    2015-01-01

    The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilyl)ethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future.

  19. Designing immersion exhibits as border-crossing environments

    DEFF Research Database (Denmark)

    Mortensen, Marianne Foss

    2010-01-01

    be applied to achieve an understanding of the immersion exhibit form. The argument proceeds by demonstrating how the characteristics of immersion exhibits, and visitors to them, classify them as microcultures, and examining the implications of this for exhibit design using a hypothetical immersion exhibit...

  20. Rebond strength of bonded lingual wire retainers

    NARCIS (Netherlands)

    van Westing, K.; Algera, T.J.; Kleverlaan, C.J.

    2012-01-01

    There is no consensus in the literature concerning the rebonding procedure for orthodontic retainers. The aim of this in vitro study was to evaluate the bond and rebond strength of retainers bonded to enamel surfaces with and without composite remnants. The retainers were bonded with Excite and

  1. 36 CFR 9.48 - Performance bond.

    Science.gov (United States)

    2010-07-01

    ... Secretary or his designee, cash or negotiable bonds of the U.S. Government. The cash deposit or the market... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Performance bond. 9.48... MINERALS MANAGEMENT Non-Federal Oil and Gas Rights § 9.48 Performance bond. (a) Prior to approval of a plan...

  2. 43 CFR 23.9 - Performance bond.

    Science.gov (United States)

    2010-10-01

    ... cash or negotiable bonds of the U.S. Government. The cash deposit or the market value of such... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Performance bond. 23.9 Section 23.9 Public... LANDS § 23.9 Performance bond. (a)(1) Upon approval of an exploration plan or mining plan, the operator...

  3. 36 CFR 9.13 - Performance bond.

    Science.gov (United States)

    2010-07-01

    ... deposit or the market value of such securities shall be at least equal to the required sum of the bond. (c... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Performance bond. 9.13... MINERALS MANAGEMENT Mining and Mining Claims § 9.13 Performance bond. (a) Upon approval of a plan of...

  4. Bond Valuation for Colleges and Universities.

    Science.gov (United States)

    National Association of College and University Business Officers, Washington, DC.

    Bond valuation is examined to provide college administrators a more thorough understanding of the process to help them in developing their market values, or to help them in moving to a market valuation on bond holdings. Two methods presently used to value bonds, a matrix system and a trader quotation method, are described. An overview of bond…

  5. 30 CFR 800.21 - Collateral bonds.

    Science.gov (United States)

    2010-07-01

    ... a margin which is the ratio of bond value to market value, as determined by the regulatory authority... value of collateral exceed the market value. (f) Persons with an interest in collateral posted as a bond... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Collateral bonds. 800.21 Section 800.21 Mineral...

  6. Metal bonding during sputter film deposition

    NARCIS (Netherlands)

    Shimatsu, T.; Shimatsu, T.; Mollema, R.H.; Monsma, D.J.; Keim, Enrico G.; Lodder, J.C.

    1998-01-01

    We studied the bonding between two flat Si substrates with thin metal films. The bonding was accomplished during thin film sputter deposition on contamination free surfaces of metal films. In this work we used Ti and Pt. Successful bonding of these metal films (each having a thickness of 10–20 nm)

  7. 75 FR 39730 - Tribal Economic Development Bonds

    Science.gov (United States)

    2010-07-12

    ... Tribal Economic Development Bonds AGENCY: Department of the Treasury, Departmental Offices. ACTION... from Indian Tribal Governments regarding the Tribal Economic Development Bond provision in Section 7871... ``Tribal Economic Development Bonds,'' under Section 7871(f) of the Internal Revenue Code (``Code'') to...

  8. Low temperature anodic bonding to silicon nitride

    DEFF Research Database (Denmark)

    Weichel, Steen; Reus, Roger De; Bouaidat, Salim

    2000-01-01

    Low-temperature anodic bonding to stoichiometric silicon nitride surfaces has been performed in the temperature range from 3508C to 4008C. It is shown that the bonding is improved considerably if the nitride surfaces are either oxidized or exposed to an oxygen plasma prior to the bonding. Both bulk...

  9. 36 CFR 223.35 - Performance bond.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Performance bond. 223.35 Section 223.35 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE SALE AND... Performance bond. Timber sale contracts may require the purchaser to furnish a performance bond for...

  10. 25 CFR 216.8 - Performance bond.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Performance bond. 216.8 Section 216.8 Indians BUREAU OF... RECLAMATION OF LANDS General Provisions § 216.8 Performance bond. (a) Upon approval of an exploration plan or mining plan, the operator shall be required to file a suitable performance bond of not less than $2,000...

  11. Valence-Bond Theory and Chemical Structure.

    Science.gov (United States)

    Klein, Douglas J.; Trinajstic, Nenad

    1990-01-01

    Discussed is the importance of valence bond theory on the quantum-mechanical theory of chemical structure and the nature of the chemical bond. Described briefly are early VB theory, development of VB theory, modern versions, solid-state applications, models, treatment in textbooks, and flaws in criticisms of valence bond theory. (KR)

  12. A Model for the Chemical Bond

    Science.gov (United States)

    Magnasco, Valerio

    2004-01-01

    Bond stereochemistry in polyatomic hydrides is explained in terms of the principle of bond energies maximization, which yields X-H straight bonds and suggests the formation of appropriate sp hybrids on the central atom. An introduction to the electron charge distribution in molecules is given, and atomic, overlap, gross and formal charges are…

  13. 21 CFR 1005.23 - Bonds.

    Science.gov (United States)

    2010-04-01

    ... single-entry bond, customs Form 7551 or term bond, customs Form 7553 or 7595, containing a condition for... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bonds. 1005.23 Section 1005.23 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) RADIOLOGICAL HEALTH...

  14. Hydroxide catalysis bonding of silicon carbide

    NARCIS (Netherlands)

    Veggel, A.A. van; Ende, D.A. van den; Bogenstahl, J.; Rowan, S.; Cunningham, W.; Gubbels, G.H.M.; Nijmeijer, H.

    2008-01-01

    For bonding silicon carbide optics, which require extreme stability, hydroxide catalysis bonding is considered [Rowan, S., Hough, J. and Elliffe, E., Silicon carbide bonding. UK Patent 040 7953.9, 2004. Please contact Mr. D. Whiteford for further information: D.Whiteford@admin.gla.ac.uk]. This

  15. Wood structure and adhesive bond strength

    Science.gov (United States)

    Charles R. Frihart

    2006-01-01

    Much of the literature on the bonding of wood and other lignocellulosic materials has concentrated on traditional adhesion theories. This has led to misconceptions because wood is a porous material on both the macroscopic and microscopic levels. A better understanding of wood bonding can be developed by investigating the theories of adhesion and bond strength, taking...

  16. Bond Percolation on Multiplex Networks

    Science.gov (United States)

    Hackett, A.; Cellai, D.; Gómez, S.; Arenas, A.; Gleeson, J. P.

    2016-04-01

    We present an analytical approach for bond percolation on multiplex networks and use it to determine the expected size of the giant connected component and the value of the critical bond occupation probability in these networks. We advocate the relevance of these tools to the modeling of multilayer robustness and contribute to the debate on whether any benefit is to be yielded from studying a full multiplex structure as opposed to its monoplex projection, especially in the seemingly irrelevant case of a bond occupation probability that does not depend on the layer. Although we find that in many cases the predictions of our theory for multiplex networks coincide with previously derived results for monoplex networks, we also uncover the remarkable result that for a certain class of multiplex networks, well described by our theory, new critical phenomena occur as multiple percolation phase transitions are present. We provide an instance of this phenomenon in a multiplex network constructed from London rail and European air transportation data sets.

  17. Bond Percolation on Multiplex Networks

    Directory of Open Access Journals (Sweden)

    A. Hackett

    2016-04-01

    Full Text Available We present an analytical approach for bond percolation on multiplex networks and use it to determine the expected size of the giant connected component and the value of the critical bond occupation probability in these networks. We advocate the relevance of these tools to the modeling of multilayer robustness and contribute to the debate on whether any benefit is to be yielded from studying a full multiplex structure as opposed to its monoplex projection, especially in the seemingly irrelevant case of a bond occupation probability that does not depend on the layer. Although we find that in many cases the predictions of our theory for multiplex networks coincide with previously derived results for monoplex networks, we also uncover the remarkable result that for a certain class of multiplex networks, well described by our theory, new critical phenomena occur as multiple percolation phase transitions are present. We provide an instance of this phenomenon in a multiplex network constructed from London rail and European air transportation data sets.

  18. Immunogenicity and safety of concomitant administration of a measles, mumps and rubella vaccine (M-M-RvaxPro® and a varicella vaccine (VARIVAX® by intramuscular or subcutaneous routes at separate injection sites: a randomised clinical trial

    Directory of Open Access Journals (Sweden)

    Thomas Stéphane

    2009-04-01

    Full Text Available Abstract Background When this trial was initiated, the combined measles, mumps and rubella (MMR vaccine was licensed for subcutaneous administration in all European countries and for intramuscular administration in some countries, whereas varicella vaccine was licensed only for subcutaneous administration. This study evaluated the intramuscular administration of an MMR vaccine (M-M-RvaxPro® and a varicella vaccine (VARIVAX® compared with the subcutaneous route. Methods An open-label randomised trial was performed in France and Germany. Healthy children, aged 12 to18 months, received single injections of M-M-RvaxPro and VARIVAX concomitantly at separate injection sites. Both vaccines were administered either intramuscularly (IM group, n = 374 or subcutaneously (SC group, n = 378. Immunogenicity was assessed before vaccination and 42 days after vaccination. Injection-site erythema, swelling and pain were recorded from days 0 to 4 after vaccination. Body temperature was monitored daily between 0 and 42 days after vaccination. Other adverse events were recorded up to 42 days after vaccination and serious adverse events until the second study visit. Results Antibody response rates at day 42 in the per-protocol set of children initially seronegative to measles, mumps, rubella or varicella were similar between the IM and SC groups for all four antigens. Response rates were 94 to 96% for measles, 98% for both mumps and rubella and 86 to 88% for varicella. For children initially seronegative to varicella, 99% achieved the seroconversion threshold (antibody concentrations of ≥ 1.25 gpELISA units/ml. Erythema and swelling were the most frequently reported injection-site reactions for both vaccines. Most injection-site reactions were of mild intensity or small size (≤ 2.5 cm. There was a trend for lower rates of injection-site erythema and swelling in the IM group. The incidence and nature of systemic adverse events were comparable for the two routes

  19. Hydrogen-Bonding Modification in Biuret Under Pressure.

    Science.gov (United States)

    Borstad, Gustav M; Ciezak-Jenkins, Jennifer A

    2017-02-02

    Biuret (C2H5N3O2) has been studied to 30 GPa by Raman spectroscopy and 50 GPa by X-ray diffraction. Raman peaks exhibit shoulders and splitting that suggests that the molecules undergo reorientation in response to compression. These are observed in three pressure ranges: the first from 3-5 GPa, the second from 8-12 GPa, and finally from 16-20 GPa. The particular modes in the sample that are observed to change in the Raman are strongly linked to the molecular vibrations involving the N-H and the C═O bond, which are most strongly coupled to the hydrogen-bonded lattice structure. The X-ray diffraction suggests that the crystal maintains a monoclinic structure to the highest pressures studied. Although there was a considerable degree of hysteresis observed in some X-ray runs, all the changes observed under pressure are reversible.

  20. Creating Virtual Exhibitions for Educational and Cultural Development

    Directory of Open Access Journals (Sweden)

    Gabriela DUMITRESCU

    2014-01-01

    Full Text Available The paper presents different tools and mechanisms to implement a virtual exhibition in different cultural areas, such as museums and libraries. Quality characteristics of virtual exhibitions are identified and described. The possibility to create native mobile applications for virtual exhibitions presentation is analyzed. The functional flow of creating a virtual exhibition is presented and discussed. The Seals - History Treasure exhibition is presented and significant historical documents are revealed.

  1. Effect of diamond bur cutting efficacy on dentin bond strengths of different bonding systems

    Directory of Open Access Journals (Sweden)

    Shirani F.

    2009-03-01

    Full Text Available "nBackground and Aim: As composite-dentin bond strength is affected by cavity preparation and the bond strength of composite resin to new and used bur prepared dentin has not yet been evaluated, this study evaluated the effects of cutting dentin with different cutting efficacy (new and used of burs on composite-dentin shear bond strength using self-etching primer bonding system and total etching bonding system. "nMaterials and Methods: Sixty caries free human 3rd molar were sectioned in occlosal surface to expose dentin, then polished with silicon carbide paper and randomly divided into four groups. Each group was prepared in a depth of 0.5mm of dentin, using new diamond bur, or used diamond bur. To change into a used bur, each new rough diamond bur had to work on bovine enamel for 30 minutes, under a load of 150g. Then, each group was bonded, using a total etch adhesive (single Bond or a self etch adhesive (clearfil SE Bond So there were 4 groups : 1-SE Bond, New bur; 2-SE Bond , used bur; 3-Single Bond , New bur ; 4-Single Bond, used bur. Similar composite capsules(Filtek Z250 were bonded to dentin surface and cured. specimens were stored in physiologic saline for 48h at 370 c , then put under shearing load to define composite - dentin shear bond strength. Results were interpreted via statistical analysis (T-test & two - way variance. "nResults: Shear bond strength of each group was as follows: 1-(27.3Mpa, 2-(33.5Mpa, 3-(16.9Mpa 4-(19.3Mpa. Statistical analysis proved that shear bond strength of used diamond bur prepared groups (2,4 was more than new diamond bur prepared ones (1,3. This statistical difference, specially, was seen between SE Bond groups (1,2 but not between single Bond groups (3,4. Also, shear bond strength of (SE Bond bonded groups (1,2 were more significantly than (single Bond bonded ones (3,4. "nConclusion: This study show that Bur cutting efficiency influences composite - dentin shear bond strength especially when the

  2. Effect of ethanol-wet-bonding technique on resin–enamel bonds

    Directory of Open Access Journals (Sweden)

    Muhammet Kerim Ayar

    2014-03-01

    Conclusion: The ethanol-wet-bonding technique may increase the bond strength of commercial adhesives to enamel. The chemical composition of the adhesives can affect the bond strength of adhesives when bonding to acid-etched enamel, using the ethanol-wet-bonding technique. Some adhesive systems used in the present study may simultaneously be applied to enamel and dentin using ethanol-wet-bonding. Furthermore, deploying ethanol-wet-bonding for the tested commercial adhesives to enamel can increase the adhesion abilities of these adhesives to enamel.

  3. Dynamic Integration of Emerging Market Bond Yields into the Global Bond Market

    OpenAIRE

    Anmar Pretorius and Alain Kabundi

    2014-01-01

    This paper investigates empirically the integration of bond markets of emerging market economies into the global bond markets from 2003 to 2012. The paper employs factor analysis based on the Arbitrage Pricing Theory to extract global factors from a panel of 38 bond yields of advanced and emerging market economies.The results reveal that bond yields in advanced economies, which constitute the driving forces behind the global bond market, do not dominate in explaining the variation of emerging...

  4. Valence Bond Theory Reveals Hidden Delocalized Diradical Character of Polyenes.

    Science.gov (United States)

    Gu, Junjing; Wu, Wei; Danovich, David; Hoffmann, Roald; Tsuji, Yuta; Shaik, Sason

    2017-07-12

    The nature of the electronic-structure of polyenes, their delocalization features, and potential diradicaloid characters constitute a fundamental problem in chemistry. To address this problem, we used valence bond self-consistent field (VBSCF) calculations and modeling of polyenes, C2nH2n+2 (n = 2-10). The theoretical treatment shows that starting with n = 5, the polyene's wave function is mainly a shifting 1,4-diradicaloid, a character that increases as the chain length increases, while the contribution of the fundamental Lewis structure with alternating double and single bonds (1) decays quite fast and becomes minor relative to the diradicaloid pack. We show how, nevertheless, it is this wave function that predicts that polyenes will still exhibit alternating short/long CC bonds like the fundamental structure 1. Furthermore, despite the decay of the VB contribution of 1, it remains the single structure with the largest weight among all the individual structures. The mixing of all the 1,4-diradicaloid structures into 1 follows perturbation theory rules, with the result that the delocalization energy due to this mixing is additive and behaves as a linear function of the number of the double bonds, ΔEdel = -6.9 × n (kcal mol(-1)). The VB modeling shows that while the conjugation stabilizes structure 1, this stabilization energy is energetically overridden by the Pauli repulsion between two adjacent double bonds. Nevertheless, unsubstituted polyenes remain planar; this observation is addressed. Potential manifestations of the diradicaloid nature of polyenes are discussed, and it is concluded that the diradicaloid character is clearly not a well-defined physical property as in real diradicals. Thus, we went full circle to realize that our philosophical question may not be strictly resolved. The localized/delocalized properties of polyenes seem to define a "chemical duality principle". This duality of molecular wave functions is a ubiquitous beguiling phenomenon.

  5. Hirshfeld atom refinement for modelling strong hydrogen bonds.

    Science.gov (United States)

    Woińska, Magdalena; Jayatilaka, Dylan; Spackman, Mark A; Edwards, Alison J; Dominiak, Paulina M; Woźniak, Krzysztof; Nishibori, Eiji; Sugimoto, Kunihisa; Grabowsky, Simon

    2014-09-01

    High-resolution low-temperature synchrotron X-ray diffraction data of the salt L-phenylalaninium hydrogen maleate are used to test the new automated iterative Hirshfeld atom refinement (HAR) procedure for the modelling of strong hydrogen bonds. The HAR models used present the first examples of Z' > 1 treatments in the framework of wavefunction-based refinement methods. L-Phenylalaninium hydrogen maleate exhibits several hydrogen bonds in its crystal structure, of which the shortest and the most challenging to model is the O-H...O intramolecular hydrogen bond present in the hydrogen maleate anion (O...O distance is about 2.41 Å). In particular, the reconstruction of the electron density in the hydrogen maleate moiety and the determination of hydrogen-atom properties [positions, bond distances and anisotropic displacement parameters (ADPs)] are the focus of the study. For comparison to the HAR results, different spherical (independent atom model, IAM) and aspherical (free multipole model, MM; transferable aspherical atom model, TAAM) X-ray refinement techniques as well as results from a low-temperature neutron-diffraction experiment are employed. Hydrogen-atom ADPs are furthermore compared to those derived from a TLS/rigid-body (SHADE) treatment of the X-ray structures. The reference neutron-diffraction experiment reveals a truly symmetric hydrogen bond in the hydrogen maleate anion. Only with HAR is it possible to freely refine hydrogen-atom positions and ADPs from the X-ray data, which leads to the best electron-density model and the closest agreement with the structural parameters derived from the neutron-diffraction experiment, e.g. the symmetric hydrogen position can be reproduced. The multipole-based refinement techniques (MM and TAAM) yield slightly asymmetric positions, whereas the IAM yields a significantly asymmetric position.

  6. On The Nature of the Halogen Bond.

    Science.gov (United States)

    Wang, Changwei; Danovich, David; Mo, Yirong; Shaik, Sason

    2014-09-09

    The wide-ranging applications of the halogen bond (X-bond), notably in self-assembling materials and medicinal chemistry, have placed this weak intermolecular interaction in a center of great deal of attention. There is a need to elucidate the physical nature of the halogen bond for better understanding of its similarity and differences vis-à-vis other weak intermolecular interactions, for example, hydrogen bond, as well as for developing improved force-fields to simulate nano- and biomaterials involving X-bonds. This understanding is the focus of the present study that combines the insights of a bottom-up approach based on ab initio valence bond (VB) theory and the block-localized wave function (BLW) theory that uses monomers to reconstruct the wave function of a complex. To this end and with an aim of unification, we studied the nature of X-bonds in 55 complexes using the combination of VB and BLW theories. Our conclusion is clear-cut; most of the X-bonds are held by charge transfer interactions (i.e., intermolecular hyperconjugation) as envisioned more than 60 years ago by Mulliken. This is consistent with the experimental and computational findings that X-bonds are more directional than H-bonds. Furthermore, the good linear correlation between charge transfer energies and total interaction energies partially accounts for the success of simple force fields in the simulation of large systems involving X-bonds.

  7. Liquidity in Government versus Covered Bond Markets

    DEFF Research Database (Denmark)

    Dick-Nielsen, Jens; Gyntelberg, Jacob; Sangill, Thomas

    We present findings on the secondary market liquidity of government and covered bonds in Denmark before, during and after the 2008 financial crisis. The analysis focuses on wholesale trading in the two markets and is based on a complete transaction level dataset covering November 2007 until end...... 2011. Overall, our findings suggest that Danish benchmark covered bonds by and large are as liquid as Danish government bonds - including in periods of market stress. Before the financial crisis of 2008, government bonds were slightly more liquid than covered bonds. During the crisis, trading continued...... in both markets but the government bond market experienced a brief but pronounced decline in market liquidity while liquidity in the covered bond market was more robust - partly reflective of a number of events as well as policy measures introduced in the autumn of 2008. After the crisis, liquidity...

  8. Bonding PMMA microfluidics using commercial microwave ovens

    Science.gov (United States)

    Toossi, A.; Moghadas, H.; Daneshmand, M.; Sameoto, D.

    2015-08-01

    In this paper, a novel low-cost, rapid substrate-bonding technique is successfully applied to polymethyl methacrylate (PMMA) microfluidics bonding for the first time. This technique uses a thin intermediate metallic microwave susceptor layer at the interface of the bonding site (microchannels) which produces localized heating required for bonding during microwave irradiation. The metallic susceptor pattern is designed using a multiphysics simulation model developed in ANSYS Multiphysics software (high-frequency structural simulation (HFSS) coupled with ANSYS-Thermal). In our experiments, the required microwave energy for bonding is delivered using a relatively inexpensive, widely accessible commercial microwave oven. Using this technique, simple PMMA microfluidics prototypes are successfully bonded and sealed in less than 35 seconds with a minimum measured bond strength of 1.375 MPa.

  9. Continuing bonds from a discourse analytic perspective

    Directory of Open Access Journals (Sweden)

    Ziółkowska Justyna

    2015-12-01

    Full Text Available The aim of the article is to contribute to the existing literature on continuing bonds with a deceased relative by exploration of discursive dimensions of the bonds through which the survivors construct their relationship with the person who died. The data come from five interviews with family members who survived the suicidal death of their relative. We argue that a focus upon the form and content of the survivors’ stories offers a complicated and heterogeneous picture of ‘bonding actions’. And so, assuming a constructionist view of discourse, we show two kinds of bonds. First, it is a bond related to social expectations of bereaved families. Second, it is a personal bond, part of which is a bond with a reverse direction, established and maintained by the deceased person.

  10. Adhesive bonding to polymer infiltrated ceramic.

    Science.gov (United States)

    Schwenter, Judith; Schmidli, Fredy; Weiger, Roland; Fischer, Jens

    2016-01-01

    Aim of this study was to investigate the mechanism of adhesive bonding to the polymer-infiltrated ceramic VITA Enamic [VE]. Shear bond strength was measured with three resin composite cements: RelyX Unicem 2 Automix, Clearfil SA and Variolink II on polished surfaces of VE and its components silicate ceramic [SC] and polymer [PM] (n=12). Further, the effect of etching VE with 5% HF for 15-240 s and the application of silane coupling agents was analyzed in a screening test (n=6). Shear bond strength measurements were performed after 24 h of water storage at 37°C. Significant bonding to polished substrates could only be achieved on VE and SC when silane coupling agents were used. Etching of VE with 5% HF increased shear bond strength. Following silanization of etched VE, a further increase in shear bond strength could be established. Etching for more than 30 s did not improve shear bond strength.

  11. Hydrogen-Bonding Surfaces for Ice Mitigation

    Science.gov (United States)

    Smith, Joseph G., Jr.; Wohl, Christopher J.; Kreeger, Richard E.; Hadley, Kevin R.; McDougall, Nicholas

    2014-01-01

    Ice formation on aircraft, either on the ground or in-flight, is a major safety issue. While ground icing events occur predominantly during the winter months, in-flight icing can happen anytime during the year. The latter is more problematic since it could result in increased drag and loss of lift. Under a Phase I ARMD NARI Seedling Activity, coated aluminum surfaces possessing hydrogen-bonding groups were under investigation for mitigating ice formation. Hydroxyl and methyl terminated dimethylethoxysilanes were prepared via known chemistries and characterized by spectroscopic methods. These materials were subsequently used to coat aluminum surfaces. Surface compositions were based on pure hydroxyl and methyl terminated species as well as mixtures of the two. Coated surfaces were characterized by contact angle goniometry. Receding water contact angle data suggested several potential surfaces that may exhibit reduced ice adhesion. Qualitative icing experiments performed under representative environmental temperatures using supercooled distilled water delivered via spray coating were inconclusive. Molecular modeling studies suggested that chain mobility affected the interface between ice and the surface more than terminal group chemical composition. Chain mobility resulted from the creation of "pockets" of increased free volume for longer chains to occupy.

  12. Platinum Nanoparticles Strongly Bonded to Freestanding Graphene

    Science.gov (United States)

    Thibado, Paul; Schoelz, J. K.; Ghosh, P. K.; Thompson, J.; Dong, L.; Neek-Amal, M.; Peeters, F. M.

    2015-03-01

    Freestanding graphene membranes were successfully functionalized with platinum nanoparticles (Pt NPs). The membranes were imaged using high-resolution transmission electron microscopy, revealing a homogeneous distribution of uniformly sized, single-crystal Pt NPs that exhibit a preferred orientation and nearest-neighbor distance. The Pt NPs were also found to be partially elevated by the graphene substrate, as deduced from atomic-resolution scanning tunneling microscopy (STM) images. Furthermore, the electrostatic force between the STM tip and sample was utilized to estimate the binding energy of the Pt NPs to the suspended graphene. Local strain accumulation due to strong sp3 bond formation is thought to be the origin of the Pt NP self-organization. Such detailed insight into the atomic nature of this functionalized system was only possible through the cooperation of dual microscopic techniques combined with molecular dynamics simulations. The findings are expected to shape future approaches to develop high-performance electronics based on nanoparticle-functionalized graphene as well as fuel cells using Pt NP catalysts. Financial support provided by the Office of Naval Research under Grant No. N00014-10-1-0181 and the National Science Foundation under Grant No. DMR-0855358.

  13. Fragmentation modeling of a resin bonded sand

    Science.gov (United States)

    Hilth, William; Ryckelynck, David

    2017-06-01

    Cemented sands exhibit a complex mechanical behavior that can lead to sophisticated models, with numerous parameters without real physical meaning. However, using a rather simple generalized critical state bonded soil model has proven to be a relevant compromise between an easy calibration and good results. The constitutive model formulation considers a non-associated elasto-plastic formulation within the critical state framework. The calibration procedure, using standard laboratory tests, is complemented by the study of an uniaxial compression test observed by tomography. Using finite elements simulations, this test is simulated considering a non-homogeneous 3D media. The tomography of compression sample gives access to 3D displacement fields by using image correlation techniques. Unfortunately these fields have missing experimental data because of the low resolution of correlations for low displacement magnitudes. We propose a recovery method that reconstructs 3D full displacement fields and 2D boundary displacement fields. These fields are mandatory for the calibration of the constitutive parameters by using 3D finite element simulations. The proposed recovery technique is based on a singular value decomposition of available experimental data. This calibration protocol enables an accurate prediction of the fragmentation of the specimen.

  14. A content-oriented model for science exhibit engineering

    DEFF Research Database (Denmark)

    Achiam, Marianne

    2013-01-01

    : as a means to operationalize the link between exhibit features and visitor activities; and as a template to transform scientists’ practices in the research context into visitors’ activities in the exhibit context. The resulting model of science exhibit engineering is presented and exemplified, and its......Recently, science museums have begun to review their educational purposes and redesign their pedagogies. At the most basic level, this entails accounting for the performance of individual exhibits, and indeed, in some cases, research indicates shortcomings in exhibit design: While often successful...... implications for science exhibit design are discussed at three levels: the design product, the design process, and the design methodology....

  15. Hydrogen-bonding directed crystal engineering of some molecular solids

    Science.gov (United States)

    Xue, Feng

    2000-10-01

    The design of crystalline clathrates and microporous solids is a contemporary goal in crystal engineering, in which hydrogen bonds play a central role because of their strength, directionality and flexibility. We have constructed various layer- and channel-type host structures by using hydrogen-bonding interactions. A novel hydrogen-bonded supramolecular rosette structure is generated from guanidinium and hydrogen carbonate ions in (1) and ( 2). The rosettes are fused into linear ribbons, which are cross-linked by terephthalate or 4-nitrobenzoate ions functioning as hydrogen-bond acceptors, resulting in anionic host layers with tetra-n-butylammonium guest species sandwiched between them. In (3) ˜ (6), new crystalline adducts of tetraalkylammonium terephthalate/trimesate with urea and water molecules result from hydrogen-bond directed assembly of complementary acceptors and donors that generate anionic channel- and layer-type host lattices for the accommodation of bulky hydrophobic cations. Some 4,4'-disubstituted biphenyls manifest their robustness and flexibility as supramolecular building blocks to construct host structures. 4,4'-biphenyl dicarboxylate ion has a strong tendency in generating ladder-type structure in (7) ˜ (10) due to its rigidity and effectiveness as a bifunctional hydrogen-bond acceptor. In (11) ˜ (15), 4,4 '-dicyanobiphenyl, 4,4'-bipyridine-N,N '-dioxide and 4,4'-dinitrobiphenyl exhibit a constructive interplay of strong and weak hydrogen bond functionalities that generate robust synthons. 4-Tritylbenzoic acid crystallizes via the carboxyl dimer supramolecular synthon to produce a wheel-and-axle host lattice that includes different aromatic solvents in its microporous framework in (16) ˜ (25 ), in which the host architecture is robust and yet adaptive. Based on the trigonal symmetry of 2,4,6-tris-4-(halo-phenoxy)-1,3,5-triazines (halo = chloro, bromo) and the Br3 or Cl3 supramolecular synthon, a new hexagonal host lattice has been designed

  16. Actor bonds after relationship dissolution

    DEFF Research Database (Denmark)

    Skaates, Maria Anne

    2000-01-01

    Most of the presented papers at the 1st NoRD Workshop can be classified as belonging to the business marketing approach to relationship dissolution. Two papers were conceptual, and the remaining six were empirical studies. The first conceptual study by Skaates (2000) focuses on the nature...... of the actor bonds that remain after a business relationship has ended. The study suggests that an interdisciplinary approach would provide a richer understanding of the phenomenon; this could be achieved by using e.g. Bourdieu's sociological concepts in dissolution research....

  17. Effect of the type of acidic monomer on the bond durability of two-bottle type ceramic primer.

    Science.gov (United States)

    Tanimura, Hideki

    2017-01-01

    Ceramic primers consisting of γ-methacryloxypropyl trimethoxysilane (γ-MPS) and either 4-methacryloyloxyethyl trimellitate (4-MET) or 10-methacryloyloxydecyl dihydrogen phosphate (MDP) are useful for facilitating bonding of resin cement to silica-based ceramic surfaces. However, bond stability at the resin-ceramic interface differs among commercial ceramic primers. To determine the ability of 4-MET or MDP to hydrolyze the methoxy group in γ-MPS, the author designed two-bottle experimental ceramic primers comprising γ-MPS solution and an activator solution of 4-MET or MDP. The effects of the type of acidic monomer on contact angle and ceramic bond durability of resin were investigated. MDP and 4-MET promoted chemisorption of γ-MPS on the ceramic surface and enhanced the ceramic bond strength of the resin. However, thermocycling decreased ceramic bond strengths, as reflected by the increased number of bonded specimens that exhibited interfacial resin failure. Bond strength was greater for 4-MET-activated ceramic primer than for the MDP-activated ceramic primer, although most bonded specimens exhibited interfacial resin failure. Degradation behavior differed between the 4-MET-activated and MDP-activated ceramic primers.

  18. 31 CFR 353.31 - Series HH bonds.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Series HH bonds. 353.31 Section 353... BONDS, SERIES EE AND HH Interest § 353.31 Series HH bonds. (a) General. Series HH bonds are current income bonds issued at par (face amount). Interest on a Series HH bond is paid semiannually beginning six...

  19. Dynamic Performance Optimization for Cloud Computing Using M/M/m Queueing System

    Directory of Open Access Journals (Sweden)

    Lizheng Guo

    2014-01-01

    Full Text Available Successful development of cloud computing has attracted more and more people and enterprises to use it. On one hand, using cloud computing reduces the cost; on the other hand, using cloud computing improves the efficiency. As the users are largely concerned about the Quality of Services (QoS, performance optimization of the cloud computing has become critical to its successful application. In order to optimize the performance of multiple requesters and services in cloud computing, by means of queueing theory, we analyze and conduct the equation of each parameter of the services in the data center. Then, through analyzing the performance parameters of the queueing system, we propose the synthesis optimization mode, function, and strategy. Lastly, we set up the simulation based on the synthesis optimization mode; we also compare and analyze the simulation results to the classical optimization methods (short service time first and first in, first out method, which show that the proposed model can optimize the average wait time, average queue length, and the number of customer.

  20. Revisiting Hydrogen Bond Thermodynamics in Molecular Simulations.

    Science.gov (United States)

    Sapir, Liel; Harries, Daniel

    2017-06-13

    In processes involving aqueous solutions and in almost every biomolecular interaction, hydrogen bonds play important roles. Though weak compared to the covalent bond, hydrogen bonds modify the stability and conformation of numerous small and large molecules and modulate their intermolecular interactions. We propose a simple methodology for extracting hydrogen bond strength from atomistic level simulations. The free energy associated with hydrogen bond formation is conveniently calculated as the reversible work required to reshape a completely random pair probability distribution reference state into the one found in simulations where hydrogen bonds are formed. Requiring only the probability density distribution of donor-acceptor pairs in the first solvation shell of an electronegative atom, the method uniquely defines the free energy, entropy, and enthalpy of the hydrogen bond. The method can be easily extended to molecules other than water and to multiple component mixtures. We demonstrate and apply this methodology to hydrogen bonds that form in molecular dynamics simulations between water molecules in pure water, as well as to bonds formed between different molecules in a binary mixture of a sugar (trehalose) and water. Finally, we comment on how the method should be useful in assessing the role of hydrogen bonds in different molecular mechanisms.

  1. Bond strength of composite to dentin using conventional, one-step, and self-etching adhesive systems.

    Science.gov (United States)

    Bouillaguet, S; Gysi, P; Wataha, J C; Ciucchi, B; Cattani, M; Godin, C; Meyer, J M

    2001-01-01

    This in vitro study compared the dentin bonding performance of eight adhesive systems using a microtensile bond strength test. Thirty bovine teeth were ground to 600-grit to obtain flat root-dentin surfaces. Two conventional adhesive systems (Scotchbond Multipurpose Plus, OptiBond FL), four one-step adhesive systems (Scotchbond 1, Asba S.A.C., Prime and Bond NT, Excite) and two self-etching adhesive materials (Clearfil Liner Bond 2 V and Prompt L-Pop) were evaluated. Each bonding system was applied according to manufacturer's instructions and followed by composite (Z100) application. Immediately after bonding, the teeth were prepared for microtensile testing. Bond strength to dentin was measured using a Vitrodyne V-1000 universal tester. There were 14 replicates for each material. Fractured specimens were further observed by SEM. Scotchbond Multipurpose Plus exhibited significantly (p<0.05) higher bond strength values (30.3+/-9.4 MPa) than all other materials. The bond strengths of the other materials were (from highest to lowest): Opitbond FL (22.4+/-4.3 MPa); Scotchbond 1(18.9+/-3.2); Clearfil Liner Bond 2 V (18.9+/-3.0); Prime and Bond NT (18.3+/-6.9); Asba S.A.C. (14.4+/-2.9); Excite (13.8+/-3.7); and Prompt L-Pop (9.1+/-3.3). Statistical comparisons frequently overlapped, but Optibond was significantly (p<0.05) greater than Asba, Excite, and Prompt L-Pop; whereas, Scotchbond 1 was only significantly (p<0.05) greater than Prompt L-Pop. Asba, Excite and Prompt L-Pop were not significantly different. The fracture modes were mostly adhesive. The conventional adhesive systems produced higher bond strengths to root dentin than most one-step adhesives and one self-etching adhesive; with the exception of one material in each respective system.

  2. Shear bond strength comparison between two orthodontic adhesives and self-ligating and conventional brackets.

    Science.gov (United States)

    Northrup, Rodney G; Berzins, David W; Bradley, Thomas Gerard; Schuckit, William

    2007-07-01

    To evaluate and compare the shear bond strengths of two adhesives using two types of brackets: a conventional and a self-ligating bracket system. Sixty extracted human premolars were collected. The premolars were randomly divided into three groups of 20 teeth. All three groups were direct bonded. Groups 1 and 2 used light-cured adhesive and primer (Transbond XT) with a conventional (Orthos) and a self-ligating bracket (Damon 2), respectively. Group 3 used a light-cured primer (Orthosolo) and a light-cured adhesive (Blūgloo) with a self-ligating bracket (Damon 2). The specimens were stored in distilled water at 37 degrees C for 40 +/- 2 hours, after which they were debonded and inspected for Adhesive Remnant Index (ARI) scoring. The mean shear bond strength was 15.2 MPa for group 1, 23.2 MPa for group 2, and 24.8 MPa for group 3. A one-way analysis of variance and post hoc Tukey test showed significant differences in bond strength (P .05) between groups 2 and 3. A Weibull analysis demonstrated that all three groups provided sufficient bond strength with over 90% survival rate at normal masticatory and orthodontic force levels. A Kruskal-Wallis test showed no significant difference (P > .05) in ARI scores among all three groups. All three groups demonstrated clinically acceptable bond strength. The Damon 2 self-ligating bracket exhibited satisfactory in vitro bond strength with both adhesive systems used.

  3. Bond-slip behavior of superelastic shape memory alloys for near-surface-mounted strengthening applications

    Science.gov (United States)

    Daghash, Sherif M.; Ozbulut, Osman E.

    2017-03-01

    The use of superelastic shape memory alloy (SMA) bars in the near-surface-mounted (NSM) strengthening application can offer advantages such as improved bond behavior, enhanced deformation capacity, and post-event functionality. This study investigates bond characteristics and load transfer mechanisms between NSM SMA reinforcement and concrete. A modified pull-out test specimen that consists of a C-shaped concrete block, where the NSM reinforcement are placed at the center of gravity of the block, was used for experimental investigations. The effects of various parameters such as epoxy type, bonded length, bar diameter, and mechanical anchorage on the bond behavior were studied. The slip of the SMA reinforcement relative to concrete was measured using an optical measurement system and the bond-slip curves were developed. Results indicate that the sandblasted SMA bars exhibit satisfactory bond behavior when used with the correct filling material in NSM strengthening applications, while the mechanical anchorage of SMA bars can significantly increase the bond resistance.

  4. Weight lifting can facilitate appreciative comprehension for museum exhibits

    Directory of Open Access Journals (Sweden)

    Yuki eYamada

    2014-04-01

    Full Text Available Appreciation of exhibits in a museum can be equated to a virtual experience of lives in the contexts originally surrounding the exhibits. Here we focus on the importance of weight information, and hence tested whether experiencing a weight during museum exhibit appreciation affects the beholders’ satisfaction and recognition memory for the exhibits. An experiment was performed at a museum exhibiting skeletal preparations of animals. We used nine preparations and prepared four weight stimuli as weight cues in accordance with the actual weight of four of the preparations: Remaining five preparations was displayed without weight stimuli. In the cued condition, participants were asked to lift up the weight stimuli during their observation of the four exhibits. In the uncued condition, participants observed the exhibits without touching the weight stimuli. After observation of the exhibits, the participants responded to a questionnaire that measured their impressions of the exhibits and the museum, and performed a recognition test on the exhibits. Results showed that memory performance was better and viewing duration was longer with weight lifting instruction than without instruction. A factor analysis on the questionnaires revealed four factors (likeability, contentment, value, and quality. A path analysis showed indirect effects of viewing duration on memory performance and willingness-to-pay for the museum appreciation through the impression factors. Our findings provide insight into a new interactive exhibition that enables long appreciation producing positive effects on visitors’ impression, memory, and value estimation for exhibits.

  5. Weight lifting can facilitate appreciative comprehension for museum exhibits.

    Science.gov (United States)

    Yamada, Yuki; Harada, Shinya; Choi, Wonje; Fujino, Rika; Tokunaga, Akinobu; Gao, Yueyun; Miura, Kayo

    2014-01-01

    Appreciation of exhibits in a museum can be equated to a virtual experience of lives in the contexts originally surrounding the exhibits. Here we focus on the importance of weight information, and hence tested whether experiencing a weight during museum exhibit appreciation affects the beholders' satisfaction and recognition memory for the exhibits. An experiment was performed at a museum exhibiting skeletal preparations of animals. We used nine preparations and prepared four weight stimuli as weight cues in accordance with the actual weight of four of the preparations: Remaining five preparations was displayed without weight stimuli. In the cued condition, participants were asked to lift up the weight stimuli during their observation of the four exhibits. In the uncued condition, participants observed the exhibits without touching the weight stimuli. After observation of the exhibits, the participants responded to a questionnaire that measured their impressions of the exhibits and the museum, and performed a recognition test on the exhibits. Results showed that memory performance was better and viewing duration was longer with weight lifting instruction than without instruction. A factor analysis on the questionnaires revealed four factors (likeability, contentment, value, and quality). A path analysis showed indirect effects of viewing duration on memory performance and willingness-to-pay (WTP) for the museum appreciation through the impression factors. Our findings provide insight into a new interactive exhibition that enables long appreciation producing positive effects on visitors' impression, memory, and value estimation for exhibits.

  6. 78 FR 7849 - Culturally Significant Objects Imported for Exhibition

    Science.gov (United States)

    2013-02-04

    ... Culturally Significant Objects Imported for Exhibition Determinations: ``Edwardian Opulence: British Art at... April 15, 2003), I hereby determine that the objects to be included in the exhibition ``Edwardian Opulence: British Art at the Dawn of the Twentieth Century,'' imported from abroad for temporary exhibition...

  7. 76 FR 68808 - Culturally Significant Objects Imported for Exhibition

    Science.gov (United States)

    2011-11-07

    ... Exhibition Determinations: ``Transition to Christianity: Art of Late Antiquity, 3rd-7th Century AD'' SUMMARY... objects to be included in the exhibition ``Transition to Christianity: Art of Late Antiquity, 3rd-7th Century AD,'' imported from abroad for temporary exhibition within the United States, are of cultural...

  8. 76 FR 52378 - Culturally Significant Objects Imported for Exhibition

    Science.gov (United States)

    2011-08-22

    ... Culturally Significant Objects Imported for Exhibition Determinations: ``5,000 Years of Chinese Jade..., Smithsonian Institution'' Exhibition ACTION: Notice, correction. SUMMARY: On July 29, 2011, notice was... the Department of State pertaining to the exhibition ``5,000 Years of Chinese Jade Featuring...

  9. 45 CFR 1160.5 - Eligibility for domestic exhibitions.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Eligibility for domestic exhibitions. 1160.5... AND ARTIFACTS INDEMNITY ACT § 1160.5 Eligibility for domestic exhibitions. An indemnity agreement for a domestic exhibition made under these regulations shall cover eligible items from the United States...

  10. 45 CFR 1160.4 - Eligibility for international exhibitions.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Eligibility for international exhibitions. 1160.4... AND ARTIFACTS INDEMNITY ACT § 1160.4 Eligibility for international exhibitions. An indemnity agreement for an international exhibition made under these regulations shall cover: (a) Eligible items from...

  11. 75 FR 6079 - Culturally Significant Objects Imported for Exhibition

    Science.gov (United States)

    2010-02-05

    ... Culturally Significant Objects Imported for Exhibition Determinations: ``Compass and Rule: Architecture as... 15, 2003 , I hereby determine that the objects to be included in the exhibition ``Compass and Rule: Architecture as Mathematical Practice in England, 1500-1750,'' imported from abroad for temporary exhibition...

  12. 33 CFR 20.807 - Exhibits and documents.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Exhibits and documents. 20.807 Section 20.807 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY GENERAL RULES... Evidence § 20.807 Exhibits and documents. (a) Each exhibit must be numbered and marked for identification...

  13. The Nature of the Hydrogen Bond Outline of a Comprehensive Hydrogen Bond Theory

    CERN Document Server

    Gilli, Gastone

    2009-01-01

    Hydrogen bond (H-bond) effects are known: it makes sea water liquid, joins cellulose microfibrils in trees, shapes DNA into genes and polypeptide chains into wool, hair, muscles or enzymes. Its true nature is less known and we may still wonder why O-H...O bond energies range from less than 1 to more than 30 kcal/mol without apparent reason. This H-bond puzzle is re-examined here from its very beginning and presented as an inclusive compilation of experimental H-bond energies andgeometries.New concepts emerge from this analysis: new classes of systematically strong H-bonds (CAHBs and RAHBs: cha

  14. Chemical Bonding: The Orthogonal Valence-Bond View

    Directory of Open Access Journals (Sweden)

    Alexander F. Sax

    2015-04-01

    Full Text Available Chemical bonding is the stabilization of a molecular system by charge- and spin-reorganization processes in chemical reactions. These processes are said to be local, because the number of atoms involved is very small. With multi-configurational self-consistent field (MCSCF wave functions, these processes can be calculated, but the local information is hidden by the delocalized molecular orbitals (MO used to construct the wave functions. The transformation of such wave functions into valence bond (VB wave functions, which are based on localized orbitals, reveals the hidden information; this transformation is called a VB reading of MCSCF wave functions. The two-electron VB wave functions describing the Lewis electron pair that connects two atoms are frequently called covalent or neutral, suggesting that these wave functions describe an electronic situation where two electrons are never located at the same atom; such electronic situations and the wave functions describing them are called ionic. When the distance between two atoms decreases, however, every covalent VB wave function composed of non-orthogonal atomic orbitals changes its character from neutral to ionic. However, this change in the character of conventional VB wave functions is hidden by its mathematical form. Orthogonal VB wave functions composed of orthonormalized orbitals never change their character. When localized fragment orbitals are used instead of atomic orbitals, one can decide which local information is revealed and which remains hidden. In this paper, we analyze four chemical reactions by transforming the MCSCF wave functions into orthogonal VB wave functions; we show how the reactions are influenced by changing the atoms involved or by changing their local symmetry. Using orthogonal instead of non-orthogonal orbitals is not just a technical issue; it also changes the interpretation, revealing the properties of wave functions that remain otherwise undetected.

  15. Bonding Durability of Four Adhesive Systems

    Science.gov (United States)

    Seyed Tabai, Elaheh; Mohammadi Basir, Mahshid

    2015-01-01

    Objectives: This study aimed to compare the durability of four adhesive systems by assessing their microtensile bond strength (MTBS) and microleakage during six months of water storage. Materials and Methods: A total of 128 human third molars were used. The adhesives tested were Scotch Bond Multipurpose (SBMP), Single Bond (SB), Clearfil-SE bond (CSEB), and All-Bond SE (ABSE). After sample preparation for MTBS testing, the microspecimens were subjected to microtensile tester after one day and six months of water storage. For microleakage evaluation, facial and lingual class V cavities were prepared and restored with composite. After thermocycling, microleakage was evaluated. Bond strength values were subjected to one-way ANOVA and Tamhane’s test, and the microleakage data were analyzed by the Kruskal-Wallis, Dunn, Mann Whitney and Wilcoxon tests (Pself-etch adhesives at the gingival margin or MTBS of CSEB and SB. PMID:27123015

  16. Halogen Bonding in Nucleic Acid Complexes.

    Science.gov (United States)

    Kolář, Michal H; Tabarrini, Oriana

    2017-11-09

    Halogen bonding (X-bonding) has attracted notable attention among noncovalent interactions. This highly directional attraction between a halogen atom and an electron donor has been exploited in knowledge-based drug design. A great deal of information has been gathered about X-bonds in protein-ligand complexes, as opposed to nucleic acid complexes. Here we provide a thorough analysis of nucleic acid complexes containing either halogenated building blocks or halogenated ligands. We analyzed close contacts between halogens and electron-rich moieties. The phosphate backbone oxygen is clearly the most common halogen acceptor. We identified 21 X-bonds within known structures of nucleic acid complexes. A vast majority of the X-bonds is formed by halogenated nucleobases, such as bromouridine, and feature excellent geometries. Noncovalent ligands have been found to form only interactions with suboptimal interaction geometries. Hence, the first X-bonded nucleic acid binder remains to be discovered.

  17. [Review of the pharmaceutical exhibitions in the Meiji Era (Supplement)].

    Science.gov (United States)

    Koyama, T

    1994-01-01

    The author described (Jpn. J. History Pharm. 16(1), 9-20 (1981) the Review of the Pharmaceutical Exhibitions in the Meiji era. But afterwards the author found there were omissions of three exhibitions. These are the Nagaoka, the Osaka, and the Akita Exhibitions. The Nagaoka Exhibition was organized by the Nagaoka Pharmacists Association in June, 1890. The Osaka Exhibition opened on Jan. 18, 1891 by Osaka Branch of the Pharmaceutical Society of Japan. The Akita Pharmaceutical Exhibition was held on Sept. 24-26, 1892, as the chief event of the opening ceremony of the Akita Drug-Trader Association, united pharmacists, druggists, and drug-manufacturers throughout Akita Prefecture. It is the most large-scaled of the three. The exhibits were 1,419, and the visitors were above 8,830. The planning originated with a young pharmacist Masayasu Hanyu.

  18. Digital Natives: Creating Emergent Exhibitions through Digital Technologies

    DEFF Research Database (Denmark)

    Smith, Rachel Charlotte; Iversen, Ole Sejer; Dindler, Christian

    2011-01-01

    Digital Technology can support the creation of dialogical spaces in the museum, both playful and reflective, that allow audiences to engage in the ongoing construction and reproduction of cultural heritage creating novel connections between self and others and between past, present and future....... In this way, digital technology can contribute to the creation of emergent exhibitions in which the exhibition is created in dialogue between audiences and the museum. We present experiences from a current research project, the Digital Natives exhibition, in which digital technology was designed...... as an integral part of the exhibition to encourage dialogue between audiences and the exhibition materials and thereby investigate how the exhibition emerge as a result of this dialogic co-construction inside the exhibition space. In short, the opportunities offered by digital technologies prompts us to consider...

  19. Scalable bonding of nanofibrous polytetrafluoroethylene (PTFE) membranes on microstructures

    Science.gov (United States)

    Mortazavi, Mehdi; Fazeli, Abdolreza; Moghaddam, Saeed

    2018-01-01

    Expanded polytetrafluoroethylene (ePTFE) nanofibrous membranes exhibit high porosity (80%–90%), high gas permeability, chemical inertness, and superhydrophobicity, which makes them a suitable choice in many demanding fields including industrial filtration, medical implants, bio-/nano- sensors/actuators and microanalysis (i.e. lab-on-a-chip). However, one of the major challenges that inhibit implementation of such membranes is their inability to bond to other materials due to their intrinsic low surface energy and chemical inertness. Prior attempts to improve adhesion of ePTFE membranes to other surfaces involved surface chemical treatments which have not been successful due to degradation of the mechanical integrity and the breakthrough pressure of the membrane. Here, we report a simple and scalable method of bonding ePTFE membranes to different surfaces via the introduction of an intermediate adhesive layer. While a variety of adhesives can be used with this technique, the highest bonding performance is obtained for adhesives that have moderate contact angles with the substrate and low contact angles with the membrane. A thin layer of an adhesive can be uniformly applied onto micro-patterned substrates with feature sizes down to 5 µm using a roll-coating process. Membrane-based microchannel and micropillar devices with burst pressures of up to 200 kPa have been successfully fabricated and tested. A thin layer of the membrane remains attached to the substrate after debonding, suggesting that mechanical interlocking through nanofiber engagement is the main mechanism of adhesion.

  20. How to measure Corporate Bond Liquidity?

    OpenAIRE

    Houweling, Patrick; Mentink, A.A.; Vorst, Ton

    2003-01-01

    textabstractWe consider eight different measures (issued amount, coupon, listed, age, missing prices, price volatility, number of contributors and yield dispersion) to approximate corporate bond liquidity and use a five-variable model to control for maturity, credit and currency differences between bonds. The null hypothesis that liquidity risk is not priced in our data set of euro corporate bonds is rejected for seven out of eight liquidity measures. We find significant liquidity premia, ran...

  1. Extremely strong contiguous hydrogen bonding arrays

    OpenAIRE

    Thomson, Patrick

    2013-01-01

    When multiple hydrogen bonds lie in-plane and parallel to each other in close proximity, they experience additional positive or negative secondary electrostatic interactions. When a pair of molecules are arranged such that every hydrogen bond acceptor is on one molecule and every hydrogen bond donor is on another, the positive secondary electrostatic interactions are maximised, and thus the association constant of the complex is enhanced. This thesis will present the develop...

  2. Explosively Bonded Gun Tube Liner Development

    Science.gov (United States)

    2015-04-01

    some concern was the occasional appearance of iron-Ta intermetallics near the liner-steel interface. This is a brittle phase and subject to...Montgomery JS, de Rosset WS. Examination of intermetallic phases and residual stresses resulting from explosive bonding of refractory metal gun tube...caliber smoothbore gun tube. The metallic bond produced by explosive bonding is extremely strong and presumably would keep the liner in place. In Phase

  3. Strength Optimization of Thermally Bonded Spunbond Nonwovens

    OpenAIRE

    Nataliya Fedorova, Ph.D; Svetlana Verenich, Ph.D.; Behnam Pourdeyhimi, Ph.D.

    2007-01-01

    Recent research on all aspects of thermally point bonded nonwovens has led to considerable improvements in the understanding of material requirements for these nonwovens, the changes that occur during bonding and the resultant deterioration of the mechanical properties of the nonwoven materials. This paper addresses how one may use a bicomponent fiber technology to overcome the shortcomings of the thermal bonding and obtain high strength spunbond fabrics. In particular, we present the utility...

  4. Thin films of molecular materials synthesized from C{sub 32}H{sub 20}N{sub 10}M (M Co, Pb, Fe): Film formation, electrical and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360, Coyoacan, 04510 Mexico, D.F. (Mexico); Sanchez Vergara, M.E., E-mail: elena.sanchez@anahuac.mx [Coordinacion de Ingenieria Mecatronica, Facultad de Ingenieria, Universidad Anahuac del Norte, Avenida Lomas Anahuac 46, Colonia Lomas Anahuac, 52786, Huixquilucan, Estado de Mexico (Mexico); Garcia Montalvo, V. [Instituto de Quimica, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico); Ortiz, A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360, Coyoacan, 04510 Mexico, D.F. (Mexico); Alvarez, J.R. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222, Colonia Ejidos de Huipulco, 14380 Mexico, D.F. (Mexico)

    2010-03-15

    In this work, the synthesis of molecular materials formed from metallic phthalocyanines and 1,4-phenylenediamine is reported. The powder and thin film ({approx}80-115 nm thickness) samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The morphology of the deposited films was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and their optical and electrical properties were studied as well. The optical parameters have been investigated using spectrophotometric measurements of transmittance in the wavelength range 200-1200 nm. The absorption spectra recorded in the UV-vis region for the deposited samples showed two bands, namely the Q and Soret bands. The optical activation energy was calculated and found to be 3.41 eV for the material with cobalt, 3.34 eV for the material including lead and 3.5 eV for the material with iron. The effect of temperature on conductivity was measured for the thin films and the corresponding conduction processes are discussed in this work.

  5. First-Principles Study on the Structural Stability and Segregation Behavior of γ-Fe/Cr2N Interface with Alloying Additives M (M = Mn, V, Ti, Mo, and Ni

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2016-07-01

    Full Text Available This study investigated the structural stability and electrochemical properties of alloying additives M (M = Mn, V, Ti, Mo, or Ni at the γ-Fe(111/Cr2N(0001 interface by the first-principles method. Results indicated that V and Ti were easily segregated at the γ-Fe(111/Cr2N(0001 interface and enhanced interfacial adhesive strength. By contrast, Ni and Mo were difficult to segregate at the γ-Fe(111/Cr2N(0001 interface. Moreover, the results of the work function demonstrated that alloying additives Mn reduced local electrochemical corrosion behavior of the γ-Fe(111/Cr2N(0001 interface by cutting down Volta potential difference (VPD between clean γ-Fe(111 and Cr2N(0001, while alloying additives V, Ti, Mo, and Ni at the γ-Fe(111/Cr2N(0001 interface magnified VPD between clean γ-Fe(111 and Cr2N(0001, which were low-potential sites that usually serve as local attack initiation points.

  6. The Synergy Effect of Ni-M (M = Mo, Fe, Co, Mn or Cr Bicomponent Catalysts on Partial Methanation Coupling with Water Gas Shift under Low H2/CO Conditions

    Directory of Open Access Journals (Sweden)

    Xinxin Dong

    2017-02-01

    Full Text Available Ni-M (M = Mo, Fe, Co, Mn or Cr bicomponent catalysts were prepared through the co-impregnation method for upgrading low H2/CO ratio biomass gas into urban gas through partial methanation coupling with water gas shift (WGS. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction (XRD, H2 temperature programmed reduction (H2-TPR, H2 temperature programmed desorption (H2-TPD, scanning electron microscopy (SEM and thermogravimetry (TG. The catalytic performances demonstrated that Mn and Cr were superior to the other three elements due to the increased fraction of reducible NiO particles, promoted dispersion of Ni nanoparticles and enhanced H2 chemisorption ability. The comparative study on Mn and Cr showed that Mn was more suitable due to its smaller carbon deposition rate and wider adaptability to various H2/CO and H2O/CO conditions, indicating its better synergy effect with Ni. A nearly 100 h, the lifetime test and start/stop cycle test further implied that 15Ni-3Mn was stable for industrial application.

  7. Effect of Bonding Application Time on Bond Strength of Composite Resin to Glass Ionomer Cement

    Directory of Open Access Journals (Sweden)

    Narges Panahandeh

    2016-08-01

    Full Text Available Objectives: This experimental study evaluated the effect of bonding application time on the microshear bond strength of composite resin to different types of glass ionomer cements (GICs.Materials and Methods: One-hundred and sixty specimens (two conventional and two resin-modified GICs were prepared and divided into 16 groups. The surface of all specimens was prepared using two different bonding systems (Frog and Stea at three different times. After setting, the composite resin (Z100 was placed over the GICs. The specimens were then stored in distilled water for 24 hours (37oC and exposed to microshear stresses at a crosshead speed of 1 mm/min. The results were analyzed using three-way ANOVA and Tukey’s test (P˂0.05.Results: In conventional GICs, bond strength was affected by the type of bonding system at different times, and bond strength was significantly higher in the Fuji II group compared to Riva Self Cure group. In the Riva Self Cure group, bond strength was significantly affected by time; whereas, the type of bonding system failed to exert a significant effect on bond strength. There was no significant correlation between the type of bonding system and the two brands of resin-modified GICs. Bond strength was not affected by the type of bonding agent; however, among the two brands of resin-modified GICs, Fuji II LC yielded a significantly stronger bond.Conclusion: It appears that the type of bonding agent does not affect the microshear bond strength, and the bonding application time affects the microshear bond strength in Riva Self Cure GICs.

  8. Steric effects governing disulfide bond interchange during thermal aggregation in solutions of beta-lactoglobulin B and alpha-lactalbumin.

    Science.gov (United States)

    Livney, Yoav D; Verespej, Edita; Dalgleish, Douglas G

    2003-12-31

    Intermolecular disulfide bond formation in pure beta-lactoglobulin (beta-Lg) B and in its 1:1 mixture with alpha-lactalbumin (alpha-La), heated at 85 degrees C for 10 min in solutions of low and high (100 mM NaCl) ionic strength and pH 6.0, was studied by reverse-phase HPLC and MALDI-TOF mass spectrometry. Disulfide bonding between beta-Lg monomers was more extensive than reported in the literature for a temperature of 68.5 degrees C, including formation of trimers connected by two of the three adjacent cysteines, C106/C119/C121. The participation of the different thiol groups in disulfide bonds appeared to depend on their location in the native structure, with surface-located cysteines more involved than internally located ones. This also applied to alpha-La-beta-Lg interactions, where the predominant participants were the surface-located alphaC111, alphaC120, alphaC61, and alphaC6. The least active participant was alphaC28, suggesting that it becomes sterically inaccessible during unfolding of the protein. High ionic strength apparently promoted disulfide bonding. The order of cysteine participation at the high ionic strength was similar to that at low ionic strength, with fewer native-location bonds observed and a lower activity of some groups, such as beta-C106/C119/C121 and alphaC61.

  9. Fusion bonding of silicon nitride surfaces

    DEFF Research Database (Denmark)

    Reck, Kasper; Østergaard, Christian; Thomsen, Erik Vilain

    2011-01-01

    results on bonding of thin and thick Si3N4 layers. The new results include high temperature bonding without any pretreatment, along with improved bonding ability achieved by thermal oxidation and chemical pretreatment. The bonded wafers include both unprocessed and processed wafers with a total silicon......While silicon nitride surfaces are widely used in many micro electrical mechanical system devices, e.g. for chemical passivation, electrical isolation or environmental protection, studies on fusion bonding of two silicon nitride surfaces (Si3N4–Si3N4 bonding) are very few and highly application...... specific. Often fusion bonding of silicon nitride surfaces to silicon or silicon dioxide to silicon surfaces is preferred, though Si3N4–Si3N4 bonding is indeed possible and practical for many devices as will be shown in this paper. We present an overview of existing knowledge on Si3N4–Si3N4 bonding and new...

  10. Tensile Bond Strength of So-called Universal Primers and Universal Multimode Adhesives to Zirconia and Lithium Disilicate Ceramics.

    Science.gov (United States)

    Elsayed, Adham; Younes, Feras; Lehmann, Frank; Kern, Matthias

    2017-01-01

    To test the bond strength and durability after artificial aging of so-called universal primers and universal multimode adhesives to lithium disilicate or zirconia ceramics. A total of 240 ceramic plates, divided into two groups, were produced and conditioned: 120 acid-etched lithium disilicate plates (IPS e.max CAD) and 120 air-abraded zirconia plates (Zenostar T). Each group was divided into five subgroups (n = 24), and a universal restorative primer or multimode universal adhesive was used for each subgroup to bond plexiglas tubes filled with a composite resin to the ceramic plate. The specimens were stored in water at 37°C for 3 days without thermal cycling, or for 30 or 150 days with 7500 or 37,500 thermal cycles between 5°C and 55°C, respectively. All specimens then underwent tensile bond strength testing. Initially, all bonding systems exhibited high TBS, but some showed a significant reduction after 30 and 150 days of storage. After 3, 30, and 150 days, Monobond Plus, which contains silane and phosphate monomer, showed significantly higher bond strengths than the other universal primer and adhesive systems. The bond strength to lithium disilicate and zirconia ceramic is significantly affected by the bonding system used. Using a separate primer containg silane and phosphate monomer provides more durable bonding than do silanes incorporated in universal multimode adhesives. Only one of five so-called universal primers and adhesives provided durable bonding to lithium disilicate and zirconia ceramic.

  11. Microstructure, Tensile Adhesion Strength and Thermal Shock Resistance of TBCs with Different Flame-Sprayed Bond Coat Materials Onto BMI Polyimide Matrix Composite

    Science.gov (United States)

    Abedi, H. R.; Salehi, M.; Shafyei, A.

    2017-10-01

    In this study, thermal barrier coatings (TBCs) composed of different bond coats (Zn, Al, Cu-8Al and Cu-6Sn) with mullite top coats were flame-sprayed and air-plasma-sprayed, respectively, onto bismaleimide matrix composites. These polyimide matrix composites are of interest to replace PMR-15, due to concerns about the toxicity of the MDA monomer from which PMR-15 is made. The results showed that pores and cracks appeared at the bond coat/substrate interface for the Al-bonded TBC because of its high thermal conductivity and diffusivity resulting in transferring of high heat flux and temperature to the polymeric substrate during top coat deposition. The other TBC systems due to the lower conductivity and diffusivity of bonding layers could decrease the adverse thermal effect on the polymer substrate during top coat deposition and exhibited adhesive bond coat/substrate interfaces. The tensile adhesion test showed that the adhesion strength of the coatings to the substrate is inversely proportional to the level of residual stress in the coatings. However, the adhesion strength of Al bond-coated sample decreased strongly after mullite top coat deposition due to thermal damage at the bond coat/substrate interface. TBC system with the Cu-6Sn bond coat exhibited the best thermal shock resistance, while Al-bonded TBC showed the lowest. It was inferred that thermal mismatch stresses and oxidation of the bond coats were the main factors causing failure in the thermal shock test.

  12. Comparison of Shear Bond Strength of New Self-etching Primer with Conventional Self-etching Primers: An In-vitro Study.

    Science.gov (United States)

    Sorake, Abhinay; Rai, Rohan; Hegde, Gautham; Suneja, Ridhima; Kumar, Naveena; Skaria, Jibin

    2015-07-01

    In the past few years, there has been a major research drive to increase bond strength between dental materials and dental hard tissue and to reduce the associated demineralization around fixed orthodontic appliances. Thus, a recent approach is to incorporate an antibacterial agent into the primer to reduce the demineralization and enhance bond strength. The objective of this study was: (1) To evaluate the shear bond strength of orthodontic preadjusted edgewise appliance brackets bonded to extracted premolar teeth with antimicrobial self-etch primer (Reliance self-etching primer, Clearfil Protect Bond) and self-etching primer without antimicrobial agent (Clearfil SE bond). (2) To compare the mean shear bond strength values of the tested materials to conventional self-etching primer Transbond Plus. A total of 125 extracted human premolar teeth were randomly divided into five groups of 25 teeth each. Each sample was embedded in an acrylic block of polymethyl meth acrylate resin till coronal portion. Instron testing machine model LR LOYD 50 K was used for testing the shear bond strength of individual samples. The results of the study showed that all five groups had adequate clinically acceptable bond strength. In intergroup comparison, there was statistically significant difference in bond strength of Reliance self-etching primer, Promt L pop, Clearfil Protect Bond, clearfil SE bond and Transbond Plus. Reliance self-etching primer showed highest bond strength, followed by Clearfil Protect Bond, clearfil SE bond, and Transbond Plus. Clearfil Protect Bond primer containing methacryloxy dodecyl pyridium bromide have been demonstrated to kill Streptococcus mutans within a short time of contact and also exhibits an inhibitory effect on the growth of bacteria on its surface.

  13. Bonded aluminum for auto bodies

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, M.J.; Seeds, A.; Sheasby, P.G.; Wheatly, J.E.; Campbell, I.G.; Kewley, D.; Selwood, P.G.; Law, F.J.

    1987-07-01

    When ferrous materials were replaced by aluminum alloys on already-designed vehicles, part weight halved, and the price doubled for bolted-on parts. However, when aluminum is an integral part of an initial design, its lower mass can help to decrease that of other parts used to support it. Decreased vehicle weight can improve fuel economy, so residual cost premiums can be recovered over a vehicle lifetime, the time required decreasing with increasing fuel costs. Several firms in England and the U.S. have been investigating design and manufacturing systems for building automotive structural frames and unibody structures from adhesively bonded sheet aluminum. This article touches some of the important points brought forth in four presentations made during SAE's Annual Congress earlier this year.

  14. Coherent Control of Bond Making

    CERN Document Server

    Levin, Liat; Rybak, Leonid; Kosloff, Ronnie; Koch, Christiane P; Amitay, Zohar

    2014-01-01

    We demonstrate for the first time coherent control of bond making, a milestone on the way to coherent control of photo-induced bimolecular chemical reactions. In strong-field multiphoton femtosecond photoassociation experiments, we find the yield of detected magnesium dimer molecules to be enhanced for positively chirped pulses and suppressed for negatively chirped pulses. Our ab initio model shows that control is achieved by purification via Franck-Condon filtering combined with chirp-dependent Raman transitions. Experimental closed-loop phase optimization using a learning algorithm yields an improved pulse that utilizes vibrational coherent dynamics in addition to chirp-dependent Raman transitions. Our results show that coherent control of binary photo-reactions is feasible even under thermal conditions.

  15. Financial Assets [share, bonds] & Ancylia

    Science.gov (United States)

    Maksoed, Wh-

    2016-11-01

    Instead Elaine Scarry: "Thermonuclear monarchy" reinvent Carry Nation since Aug 17, 1965 the Republic of Indonesia's President speech: "Reach to the Star", for "cancellation" usually found in External Debt herewith retrieved from "the Window of theWorld": Ancylia, feast in March, a month named after Mars, the god of war. "On March 19 they used to put on their biggest performance of gymnastics in order to "bribe" their god for another good year", further we have vacancy & "vacuum tube"- Bulat Air karena Pembuluh, Bulat Kata karena Mufakat" proverb from Minangkabau, West Sumatra. Follows March 19, 1984 are first prototype flight of IAI Astra Jet as well as March 19, 2012 invoice accompanies Electric car Kujang-193, Fainancial Assets [share, bonds] are the answer for "infrastructure" & state owned enterprises assets to be hedged first initial debt per capita accordances. Heartfelt gratitudes to HE. Mr. Ir. Sarwono Kusumaatmadja/PT. Smartfren INDONESIA.

  16. Effect of mucoprotein on the bond strength of resin composite to human dentin.

    Science.gov (United States)

    Pinzon, Lilliam Marie; Powers, John M; O'Keefe, Kathy L; Dusevish, Vladimir; Spencer, Paulette; Marshall, Grayson W

    2011-07-01

    The purpose of this study was to test the bond strength and analyze the morphology of the dentin-adhesive interface of two etch and rinse and two self-etch adhesive systems with two kinds of artificial saliva (with and without 450 mg/L mucin) contamination under different conditions of decontaminating the interface. Bonded specimens were sectioned perpendicularly to the bonded surface in 1-mm thick slabs. These 1-mm thick slabs were remounted in acrylic blocks and sectioned in sticks perpendicular to the bonding interfaces with a 1-mm(2) area. Nine specimens from each condition were tested after 24 h on a testing machine (Instron) at a speed of 0.5 mm/min for a total of 360 specimens. Mean and standard deviations of bond strength (MPa) were calculated. ANOVA showed significant differences as well as Fisher's PLSD intervals (p < 0.05). The following values are the results for different groups: Control group 34-60 MPa, saliva without mucin 0-52 MPa, and saliva with mucin 0-57 MPa. Failure sites were mixed and adhesive failure was common for the low bond strength results. P&BNT with ideal conditions and following the manufacturer's instructions (control) had the highest bond strengths and the dentin-adhesive interface exhibited an ideal morphology of etch-and-rinse system. SEM gave complementary visual evidence of the effect in the dentin/adhesive interface structure with some contaminated conditions compared with their respective control groups. This in vitro artificial saliva model with and without mucin showed that an organic component of saliva could increase or decrease the bond strength depending on the specific bonding agent and decontamination procedure.

  17. Effect of Self-etching Adhesives on the Bond Strength of Glass-Ionomer Cements.

    Science.gov (United States)

    Jaberi Ansari, Zahra; Panahandeh, Narges; Tabatabaei Shafiei, Zahra Sadat; Akbarzadeh Baghban, Alireza

    2014-11-01

    Adequate bond strength between glass ionomer cements and composite resin is necessary for the success of the sandwich technique. This study assessed the micro-shear bond strength of composite resin to glass-ionomer cements (GIC) using self-etch adhesives with different pH values. One hundred specimens (6×4×2 mm) were made using Fuji II and Fuji II LC GICs and treated with different adhesives as follows: Group 1:Fuji II+ Adper Prompt L-Pop, Group-2: Fuji II+SE bond, Group-3: Fuji II + AdheSE, Group-4:Fuji II+ Protect bond, Group-5: Fuji II + Single bond, Group-6:Fuji II LC+ Adper Prompt LPop, Group-7: Fuji II LC+SE bond, Group-8:Fuji II LC+ AdheSE, Group-9: Fuji II LC+ Protect bond, and Group-10: Fuji II LC+ Single bond. Each group consisted of 10 specimens. A cylinder of Z100 composite resin was placed on each sample and light cured. After 24 hours of water storage (37°C), the specimens were subjected to micro-shear bond strength tests (0.5 mm/min). Data were analyzed using two-way ANOVA and Tukey's test. The mean micro-shear bond strength of groups 1-10 was 11.66±1.79, 16.50±1.85, 18.47±1.77, 13.95±1.77, 15.27±1.49, 15.14±0.90, 20.03±1.19, 17.48±3.00, 16.24±1.98 and 16.03±1.49 MPa, respectively. There were significant differences between groups 1 and 7 (P0.05). Fuji II LC showed higher bond strength than Fuji II (Padhesive had no significant effect on micro-shear bond strength of glass-ionomer to composite resin. Resin modified glass ionomer cement (RMGIC) exhibited higher bond strength than the conventional GIC.

  18. Effect of Self-etching Adhesives on the Bond Strength of Glass-Ionomer Cements.

    Directory of Open Access Journals (Sweden)

    Zahra Jaberi Ansari

    2014-12-01

    Full Text Available Adequate bond strength between glass ionomer cements and composite resin is necessary for the success of the sandwich technique.This study assessed the micro-shear bond strength of composite resin to glass-ionomer cements (GIC using self-etch adhesives with different pH values.One hundred specimens (6×4×2 mm were made using Fuji II and Fuji II LC GICs and treated with different adhesives as follows: Group 1:Fuji II+ Adper Prompt L-Pop, Group-2: Fuji II+SE bond, Group-3: Fuji II + AdheSE, Group-4:Fuji II+ Protect bond, Group-5: Fuji II + Single bond, Group-6:Fuji II LC+ Adper Prompt LPop, Group-7: Fuji II LC+SE bond, Group-8:Fuji II LC+ AdheSE, Group-9: Fuji II LC+ Protect bond, and Group-10: Fuji II LC+ Single bond. Each group consisted of 10 specimens. A cylinder of Z100 composite resin was placed on each sample and light cured. After 24 hours of water storage (37°C, the specimens were subjected to micro-shear bond strength tests (0.5 mm/min. Data were analyzed using two-way ANOVA and Tukey's test.The mean micro-shear bond strength of groups 1-10 was 11.66±1.79, 16.50±1.85, 18.47±1.77, 13.95±1.77, 15.27±1.49, 15.14±0.90, 20.03±1.19, 17.48±3.00, 16.24±1.98 and 16.03±1.49 MPa, respectively. There were significant differences between groups 1 and 7 (P0.05. Fuji II LC showed higher bond strength than Fuji II (P<0.05.Type of self-etch adhesive had no significant effect on micro-shear bond strength of glass-ionomer to composite resin. Resin modified glass ionomer cement (RMGIC exhibited higher bond strength than the conventional GIC.

  19. A Unified Theory for the Blue- and Red-Shifting Phenomena in Hydrogen and Halogen Bonds.

    Science.gov (United States)

    Wang, Changwei; Danovich, David; Shaik, Sason; Mo, Yirong

    2017-04-11

    Typical hydrogen and halogen bonds exhibit red-shifts of their vibrational frequencies upon the formation of hydrogen and halogen bonding complexes (denoted as D···Y-A, Y = H and X). The finding of blue-shifts in certain complexes is of significant interest, which has led to numerous studies of the origins of the phenomenon. Because charge transfer mixing (i.e., hyperconjugation in bonding systems) has been regarded as one of the key forces, it would be illuminating to compare the structures and vibrational frequencies in bonding complexes with the charge transfer effect "turned on" and "turned off". Turning off the charge transfer mixing can be achieved by employing the block-localized wave function (BLW) method, which is an ab initio valence bond (VB) method. Further, with the BLW method, the overall stability gained in the formation of a complex can be analyzed in terms of a few physically meaningful terms. Thus, the BLW method provides a unified and physically lucid way to explore the nature of red- and blue-shifting phenomena in both hydrogen and halogen bonding complexes. In this study, a direct correlation between the total stability and the variation of the Y-A bond length is established based on our BLW computations, and the consistent roles of all energy components are clarified. The n(D) → σ*(Y-A) electron transfer stretches the Y-A bond, while the polarization due to the approach of interacting moieties reduces the HOMO-LUMO gap and results in a stronger orbital mixing within the YA monomer. As a consequence, both the charge transfer and polarization stabilize bonding systems with the Y-A bond stretched and red-shift the vibrational frequency of the Y-A bond. Notably, the energy of the frozen wave function is the only energy component which prefers the shrinking of the Y-A bond and thus is responsible for the associated blue-shifting. The total variations of the Y-A bond length and the corresponding stretching vibrational frequency are thus

  20. Attochemistry of Ionized Halogen, Chalcogen, Pnicogen, and Tetrel Noncovalent Bonded Clusters.

    Science.gov (United States)

    Chandra, Sankhabrata; Bhattacharya, Atanu

    2016-12-29

    In general, charge migration can occur via pure electron-electron correlation and relaxation or via coupling with nuclear motion. We must understand both aspects of charge migration through the non-hydrogen noncovalent bonds to harness full potential of the halogen-, chalcogen-, pnicogen- and tetrel-bonded photosensitive functional materials. This feature article, however, is focused on the pure relaxation- and correlation-driven charge migration, subsequent charge localization, and finally on charge-directed reactivity in the non-hydrogen noncovalent bonded clusters. Pure relaxation- and correlation-driven charge migration can occur on a several hundred attosecond (as) time scale, and this is why chemical dynamics associated with this pure electronic charge migration can be named "attochemistry". One of the efficient ways to elucidate the attochemistry is via the vertical ionization by monitoring a nonstationary electronic charge density that evolves in time while the nuclear configuration remains unchanged. So far, attochemistry of several halogen-, chalcogen-, pnicogen-, and tetrel-bonded clusters has been studied theoretically by our group. All the interesting predictions have been summarized in this Feature Article. The time scales of relaxation- and correlation-driven charge migration through the halogen, chalcogen, pnicogen, and tetrel noncovalent bonds are found to be quite similar (approximately in the range of 300-600 as) in different (1:1) AX:NH3 and AX:OH2 complexes (where A represents different substituents, such as NH2, CN, etc.). Basis sets do not exhibit any effect on the predicted charge migration time scale. A very long intermolecular distance (approximately more than 10 Å), for which (physically) no noncovalent bonding interaction can be present, ceases the intermolecular charge migration. The strength of the electron-electron correlation interaction influences the charge migration through these noncovalent bonds, making charge migration faster

  1. A 15-month evaluation of bond failures of orthodontic brackets bonded with direct versus indirect bonding technique: a clinical trial.

    Science.gov (United States)

    Menini, Anna; Cozzani, Mauro; Sfondrini, Maria Francesca; Scribante, Andrea; Cozzani, Paolo; Gandini, Paola

    2014-12-30

    The purpose of this clinical longitudinal study was to investigate the effectiveness of indirect bonding technique evaluating the number of bond failures which occurred during treatment. Fifty-two patients were selected and divided into two groups: group A (33 patients) bonded with the direct technique and group B (19 patients) bonded with the indirect technique. The number and date of bracket failure were recorded for over 15 months. Moreover, also the effect of crowding level on bracket failures was calculated. Statistical analysis was performed by means of t-test, Kaplan-Meier survival estimates and chi-squared test. No statistically significant differences were found in the total bond failure rate between direct and indirect techniques, also when comparing the upper and lower arches. The only significant difference was found comparing the posterior segment of the lower arches, in which a higher percentage of detachments were recorded in group B, bonded with the indirect technique. Moreover, no significant differences between direct and indirect bonding were found when evaluating crowding level. Orthodontic practitioners can safely use the indirect bonding technique, even in patients with severe crowding, because it does not influence the adhesive quality and the bracket survival rate.

  2. Shear bond strength of ceramic and metallic orthodontic brackets bonded with self-etching primer and conventional bonding adhesives.

    Science.gov (United States)

    Arash, Valiollah; Naghipour, Fatemeh; Ravadgar, Mehdi; Karkhah, Ahmad; Barati, Mohammad Saleh

    2017-01-01

    Adult patients typically require high-quality orthodontic treatment for ceramic brackets, but some clinicians remain concerned about the bond strength of these brackets. Therefore, the aim of this study was to determine the shear bond strength and de-bonding characteristics of metallic and ceramic brackets bonded with two types of bonding agents. In an experimental study done in 2013 in Babol, Iran, 120 extracted human maxillary premolar teeth were randomly divided into four groups as follows: HM group: metallic bracket/conventional bonding agent; SM group: metallic bracket/Transbond self-etching primer; HC group: ceramic bracket/conventional bonding agent; SC group: ceramic bracket/Transbond self-etching primer. Twenty-four hours after thermocycling (1000 cycle, 5 °C-55 °C), the shear bond strength values were measured. The amount of resin remaining on the tooth surface (adhesive remnant index: ARI) was determined under a stereomicroscope. Enamel detachment index was evaluated under a scanning electron microscope. To perform statistical analysis, ANOVA, Kruskal-Wallis, and Tukey post-hoc tests were applied. The level of significance was set at p conventional technique. Many samples showed the bracket-adhesive interface failure or failure inside the adhesive.

  3. Three substituted (E)-3-aryl-2-(thienyl)acrylonitriles: isolated molecules, simple hydrogen-bonded chains and hydrogen-bonded sheets.

    Science.gov (United States)

    Cobo, Debora; Quiroga, Jairo; de la Torre, José M; Cobo, Justo; Low, John N; Glidewell, Christopher

    2006-09-01

    The structure of (E)-2-(2-thienyl)-3-(3,4,5-trimethoxyphenyl)acrylonitrile, C16H15NO3S, contains no direction-specific intermolecular interactions. The molecules of (E)-3-(4-bromophenyl)-2-(2-thienyl)acrylonitrile, C13H8BrNS, exhibit orientational disorder of the thienyl fragment, and the molecules are linked into simple C(5) chains by a single C-H...N hydrogen bond. In (E)-3-phenyl-2-(3-thienyl)acrylonitrile, C13H9NS, the molecules are linked into sheets by a combination of one C-H...N hydrogen bond and one C-H...pi(arene) hydrogen bond.

  4. Bond-strength studies for 1-mil-diameter gold wires bonded to hybrid microcircuit substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kan, Y.R.; Prantil, V.C.

    1981-12-01

    Detailed studies of the failure probability for gold wires bonded to multiplexer substrates under severe acceleration in the W79 artillery shell environments were made. The studies included: the calculated resultant pull forces exerted on the bond joints due to the W79 acceleration environments; the suitability of the loop-hook pull tests and the use of the normal Gaussian distribution theory for statistical description of bond strengths; and the probability of failure for gold wires bonded to multiplexer substrates under artillery shell accelerations using fixed angle pull tests and a Weilbull distribution theory for the statistical description. Preliminary statistical analyses of the bond strength data obtained from the conventional loop-hook pull tests for a multiplexer substrate HMC, have shown that the ball bond is strong enough to withstand the 0.17 gram design limit load due to the W79 gun barrel environments with a very low probability of failure. For the wedge bond, however, the results of a statistical analysis for the bond strength agree with experience which shows that the wedge bonds are generally much weaker than ball bonds in multiplexer substrates, and the probability of failure may be high enough to cause a problem. The degradation of the wedge bond strength due to post-assembly testing is significant as indicated by the large increase in probability of failure for the post-assembly-tested wedge bonds. To illustrate this, consider a worst-case example which assumes all wires bonded to the hybrid microcircuit substrates have the same geometry and loading conditions. Assuming the W79 JTA has approximately 2760 of these bonded wires, the probabilities of failure are 0.0179% for virgin wedge bonds and 2.1% for post-assembly-tested wedge bonds.

  5. Hydrogen-Bond Strength of CC and GG Pairs Determined by Steric Repulsion: Electrostatics and Charge Transfer Overruled.

    Science.gov (United States)

    van der Lubbe, Stephanie C C; Fonseca Guerra, Célia

    2017-08-01

    Theoretical and experimental studies have elucidated the bonding mechanism in hydrogen bonds as an electrostatic interaction, which also exhibits considerable stabilization by charge transfer, polarization, and dispersion interactions. Therefore, these components have been used to rationalize the differences in strength of hydrogen-bonded systems. A completely new viewpoint is presented, in which the Pauli (steric) repulsion controls the mechanism of hydrogen bonding. Quantum chemical computations on the mismatched DNA base pairs CC and GG (C=cytosine, G=guanine) show that the enhanced stabilization and shorter distance of GG is determined entirely by the difference in the Pauli repulsion, which is significantly less repulsive for GG than for CC. This is the first time that evidence is presented for the Pauli repulsion as decisive factor in relative hydrogen-bond strengths and lengths. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Are Bonding Agents being Effective on the Shear Bond Strength of Orthodontic Brackets Bonded to the Composite?

    Directory of Open Access Journals (Sweden)

    Fahimeh Farzanegan

    2014-06-01

    Full Text Available Introduction: One of the clinical problems in orthodontics is the bonding of brackets tocomposite restorations. The aim of this study was to evaluate the shear bondstrength of brackets bonded to composite restorations using Excite. Methods:Forty brackets were bonded to composite surfaces, which were embedded inacrylic resin. One of the following four protocols was employed for surfacepreparation of the composite: group 1 37% phosphoric acid for 60 seconds, group2 roughening with a diamond bur plus 37% phosphoric acid for 60 seconds, group3 37% phosphoric acid for 60 seconds and the applying Excite®, group4 roughening with diamond bur plus 37% phosphoric acid for 60 seconds andapplying Excite®. Maxillary central brackets were bonded onto thecomposite prepared samples with Transbond XT. Shear Bond Strength (SBS wasmeasured by a universal testing machine. The ANOVA and Tukey test was utilizedfor data analysis. Results: There was a significant difference betweenthe four groups (P

  7. Long-range behavior of noncovalent bonds. Neutral and charged H-bonds, pnicogen, chalcogen, and halogen bonds

    Science.gov (United States)

    Nepal, Binod; Scheiner, Steve

    2015-07-01

    Ab initio calculations show the drop in interaction energy with bond stretch ΔR can be fit to a common power n, in the functional form ΔR-n. This exponent is smaller for charged H-bonds, as compared to neutral systems, where n varies in the order pnicogen bond. The decay is slowest for the electrostatic term, followed by induction and then by dispersion. The halogen bond has the greatest sensitivity to bond stretching in terms of all three components. The values of the exponent n are smaller for electrostatic energy than would be expected if it arose purely as a result of classical multipole interactions, such as dipole-dipole for the neutral systems. The exponents are larger when the fitting is done with respect to intermolecular distance R, rather than to its stretch relative to equilibrium length, although still not precisely matching what might be expected on classical grounds.

  8. Halogen light versus LED for bracket bonding: shear bond strength

    Directory of Open Access Journals (Sweden)

    Paulo Eduardo Guedes Carvalho

    2013-02-01

    Full Text Available INTRODUCTION: LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. OBJECTIVE: The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE. RESULTS: Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. CONCLUSION: It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.INTRODUÇÃO: os aparelhos de fotopolimerização por LED buscam proporcionar uma luz ativadora fria, que possibilite protocolos de polimerização do material com menor tempo de duração. OBJETIVO: avaliar a resistência à tração da colagem de braquetes, utilizando três tipos de aparelhos fotoativadores: um de luz halógena (Optilight Plus - Gnatus e outros dois de LED (Optilight CL - Gnatus; e Elipar Freelight - 3M/Espe. RESULTADOS: comparando os resultados por meio da análise de variância, o aparelho de LED Gnatus apresentou comportamento estatístico inferior em relação às outras fontes de luz, quando ativado por tempo reduzido. Já quando foi utilizado o tempo de 40 segundos, os resultados de polimerização foram compatíveis com as demais fontes avaliadas. O aparelho que apresentou melhor desempenho médio foi o de luz halógena, seguido pelo LED 3M/Espe. CONCLUSÃO: concluiu-se que os LEDs podem ser indicados na prática ortodôntica, uma vez que seja utilizado

  9. Hydrogen bond, electron donor-acceptor dimer, and residence dynamics in supercritical CO(2)-ethanol mixtures and the effect of hydrogen bonding on single reorientational and translational dynamics: A molecular dynamics simulation study.

    Science.gov (United States)

    Skarmoutsos, Ioannis; Guardia, Elvira; Samios, Jannis

    2010-07-07

    The hydrogen bonding and dynamics in a supercritical mixture of carbon dioxide with ethanol as a cosolvent (X(ethanol) approximately 0.1) were investigated using molecular dynamics simulation techniques. The results obtained reveal that the hydrogen bonds formed between ethanol molecules are significantly more in comparison with those between ethanol-CO(2) molecules and also exhibit much larger lifetimes. Furthermore, the residence dynamics in the solvation shells of ethanol and CO(2) have been calculated, revealing much larger residence times for ethanol molecules in the ethanol solvation shell. These results support strongly the ethanol aggregation effects and the slow local environment reorganization inside the ethanol solvation shell, reported in a previous publication of the authors [Skarmoutsos et al., J. Chem. Phys. 126, 224503 (2007)]. The formation of electron donor-acceptor dimers between the ethanol and CO(2) molecules has been also investigated and the calculated lifetimes of these complexes have been found to be similar to those corresponding to ethanol-CO(2) hydrogen bonds, exhibiting a slightly higher intermittent lifetime. However, the average number of these dimers is larger than the number of ethanol-CO(2) hydrogen bonds in the system. Finally, the effect of the hydrogen bonds formed between the individual ethanol molecules on their reorientational and translational dynamics has been carefully explored showing that the characteristic hydrogen bonding microstructure obtained exhibits sufficiently strong influence upon the behavior of them.

  10. The Eugenides Foundation Interactive Exhibition of Science and Technology

    Science.gov (United States)

    Kontogiannis, Ioannis

    2010-01-01

    The Interactive Exhibition of Science and Technology is installed in an area of 1200 m2 at the Eugenides Foundation. 65 interactive exhibits, designed by the "Cites des Science et de l' Industrie" are organised in themes, stimulate the visitors' mind and provoke scientific thinking. Parallel activities take place inside the exhibition, such as live science demonstrations, performed by young scientists. Extra material such as news bulletins (short news, science comics and portraits), educational paths and treasure-hunting based games, all available online as well, are prepared on a monthly basis and provided along with the visit to the exhibition. Through these exhibits and activities, scientific facts are made simple and easy to comprehend using modern presentation tools. We present details on how this exhibition acts complementary to the science education provided by schools, making it a highly sophisticated educational tool.

  11. CERN exhibition attracts over 100,000 visitors in Belgrade

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    “This must be an 'all-time record',” says Ray Lewis, CERN travelling exhibition manager. “In all my time with the various permanent and travelling exhibitions that have taken place locally and within our Member States I have never experienced such figures.”   Zarko Obradovic (left), Serbian Minister of Education, Science and Technology, and Rolf Heuer (right), CERN Director-General, at the CERN travelling exhibition in Belgrade. Indeed, in approximately 20 days of exhibition time about 120,000 people, mainly school visiters and the general public, visited the 100 m2 CERN mini-exhibition. It was set up in the centre of Belgrade in October, in association with the meeting of the Restricted European Committee for Future Accelerators (RECFA). After attending the RECFA meeting, CERN's Director-General Rofl Heuer opened the CERN exhibition on the evening of 19 October. Lectures about CERN were held every afternoon, and two public de...

  12. 77 FR 32128 - Cancellation of Bond Subject to Enhanced Bonding Requirements Upon CBP's Acceptance of Qualified...

    Science.gov (United States)

    2012-05-31

    ... Administration, Revenue Division, ATTN: Bond Team Intech 1, 6650 Telecom Drive, Indianapolis, IN 46278 or via... to take advantage of this policy must ensure that CBP's Bond Team Intech 1, within the Office of... Administration, Revenue Division, ATTN: Bond Team Intech 1, 6650 Telecom Drive, Indianapolis, IN 46278 or via...

  13. Valence-Bond Concepts in Coordination Chemistry and the Nature of Metal-Metal Bonds.

    Science.gov (United States)

    Pauling, Linus; Herman, Zelek S.

    1984-01-01

    Discusses the valence-bond method, applying it to some coordination compounds of metals, especially those involving metal-metal bonds. Suggests that transition metals can form as many as nine covalent bonds, permitting valence-theory to be extended to transition metal compounds in a more effective way than has been possible before. (JN)

  14. Motion Capture: Drawing and the Moving Image Exhibition, Letterkenny, Donegal.

    OpenAIRE

    Fay, Brian

    2013-01-01

    Motion Capture Drawing & the Moving Image A GLUCKSMAN exhibition, touring to Regional Cultural Centre, Letterkenny, Co. Donegal, 22 January – 9 March 2013 Supported by a Touring and Dissemination award from the Arts Council of Ireland/An Chomhairle Ealaíon. Motion Capture is an exhibition that explores the relationship of movement in two artistic media: drawing and the moving image. Featuring artworks from the mid-twentieth century through to the present day, the exhibition emphasises the ...

  15. Disulfide bonds are necessary for structure and activity in Aspergillus ficuum phytase.

    Science.gov (United States)

    Ullah, A H; Mullaney, E J

    1996-10-14

    The function of disulfide bonds in Aspergillus ficuum phytase was elucidated by unfolding studies, using guanidinium hydrochloride (Gu.HCl) as denaturant. Although the enzyme is totally inactivated by 0.8 M Gu.HCl, at pH 5.0, the active conformation is instantaneously restored by 0.6 M Gu.HCl, at pH 5.0. Conditions which would permit refolding of phytase are completely negated by 10 mM beta-mercaptoethanol and causes its catalytic demise at pH 7.5. Assay of free thiols using Ellman's reagent indicates that none of the thiols in the ten cysteines in phytase are free; five disulfide bonds were predicted for the enzyme. Sequence comparison of mold phytases and yeast acid phosphatases indicates four conserved cysteines. Thus, disulfide bonds play an important role in the folding of fungal phytase; any perturbation of the process of its formation causes an altered three-dimensional structure that is inconsistent with catalytic activity.

  16. 77 FR 31420 - Culturally Significant Objects Imported for Exhibition

    Science.gov (United States)

    2012-05-25

    ... abroad for temporary exhibition within the United States, are of cultural significance. The objects are... Ereli, Principal Deputy Assistant Secretary, Bureau of Educational and Cultural Affairs, Department of...

  17. Hydrogen bond dynamics in bulk alcohols.

    Science.gov (United States)

    Shinokita, Keisuke; Cunha, Ana V; Jansen, Thomas L C; Pshenichnikov, Maxim S

    2015-06-07

    Hydrogen-bonded liquids play a significant role in numerous chemical and biological phenomena. In the past decade, impressive developments in multidimensional vibrational spectroscopy and combined molecular dynamics-quantum mechanical simulation have established many intriguing features of hydrogen bond dynamics in one of the fundamental solvents in nature, water. The next class of a hydrogen-bonded liquid--alcohols--has attracted much less attention. This is surprising given such important differences between water and alcohols as the imbalance between the number of hydrogen bonds, each molecule can accept (two) and donate (one) and the very presence of the hydrophobic group in alcohols. Here, we use polarization-resolved pump-probe and 2D infrared spectroscopy supported by extensive theoretical modeling to investigate hydrogen bond dynamics in methanol, ethanol, and isopropanol employing the OH stretching mode as a reporter. The sub-ps dynamics in alcohols are similar to those in water as they are determined by similar librational and hydrogen-bond stretch motions. However, lower density of hydrogen bond acceptors and donors in alcohols leads to the appearance of slow diffusion-controlled hydrogen bond exchange dynamics, which are essentially absent in water. We anticipate that the findings herein would have a potential impact on fundamental chemistry and biology as many processes in nature involve the interplay of hydrophobic and hydrophilic groups.

  18. HYDROGEN BONDING IN THE METHANOL DIMER

    Science.gov (United States)

    In this work, two methanol molecules are placed in different arrangements to study hydrogen bonding in carbohydrate materials such as cellulose. Energy was calculated as a function of both hydrogen bond length and angle over wide ranges, using quantum mechanics (QM). The QM wavefunctions are analyze...

  19. ROLE OF DIASPORA BONDS IN DEVELOPING COUNTRIES

    Directory of Open Access Journals (Sweden)

    Y. Bunyk

    2015-08-01

    Full Text Available The article deals with the problem of the bond issue for the Diaspora as a source of financing of the national economy and a factor of development. We reveal the following factors driving demand in the diaspora bond market: targeting at a project, channels, audience and marketing. The paper shows international experience to attract migrants’ savings and use them to issue bonds. Investors consider diaspora bonds because: firstly, people who have disposable income, who can commit that income or that excess income to a long term investment should look at diaspora bonds: secondly, people who really want to participate in transforming the home country should look at diaspora bond specifically diaspora bonds related to projects: and last but not least, if there are incentives around diaspora bonds for example whether there’s tax incentive and other kinds of incentive, that also should be taken into account. Also we disclosed the possibility of using this type of securities in Ukraine and its expedience.

  20. Index Driven Price Pressure in Corporate Bonds

    DEFF Research Database (Denmark)

    Dick-Nielsen, Jens

    Inclusion and exclusion of bonds from major indices are information-free, monthly events. At these events, liquidity providers get a significant abnormal return by trading against index trackers. The return is highest for bonds that are excluded because of a recent downgrade with a one-day return...

  1. Shear bond strength of cement to zirconia

    NARCIS (Netherlands)

    Rosentritt, M.; Behr, M.; van der Zel, J.M.; Feilzer, A.J.

    2009-01-01

    This study investigated the shear bond strength (SBS) of various cements to zirconia ceramic. CoCr-cylinders were bonded to zirconia plates (20 mm × 10 mm × 2 mm; n = 8 per group) using four self-adhesive resin cements (one capsule, three hand-mixed) and four resin cements, partly in combination

  2. Interlaminar toughness of fusion bonded thermoplastic composites

    NARCIS (Netherlands)

    Sacchetti, Francisco R.

    2017-01-01

    Thermoplastic composites are of increasing interest to the aerospace industry. The melt-processability of the thermoplastic matrix allows for fast manufacturing and assembling techniques, such as thermoforming and fusion bonding, which are also highly suitable for process automation. Fusion bonding

  3. Hydrogen bond dynamics in bulk alcohols

    Energy Technology Data Exchange (ETDEWEB)

    Shinokita, Keisuke; Cunha, Ana V.; Jansen, Thomas L. C.; Pshenichnikov, Maxim S., E-mail: Maxim.Pchenitchnikov@RuG.nl [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

    2015-06-07

    Hydrogen-bonded liquids play a significant role in numerous chemical and biological phenomena. In the past decade, impressive developments in multidimensional vibrational spectroscopy and combined molecular dynamics–quantum mechanical simulation have established many intriguing features of hydrogen bond dynamics in one of the fundamental solvents in nature, water. The next class of a hydrogen-bonded liquid—alcohols—has attracted much less attention. This is surprising given such important differences between water and alcohols as the imbalance between the number of hydrogen bonds, each molecule can accept (two) and donate (one) and the very presence of the hydrophobic group in alcohols. Here, we use polarization-resolved pump-probe and 2D infrared spectroscopy supported by extensive theoretical modeling to investigate hydrogen bond dynamics in methanol, ethanol, and isopropanol employing the OH stretching mode as a reporter. The sub-ps dynamics in alcohols are similar to those in water as they are determined by similar librational and hydrogen-bond stretch motions. However, lower density of hydrogen bond acceptors and donors in alcohols leads to the appearance of slow diffusion-controlled hydrogen bond exchange dynamics, which are essentially absent in water. We anticipate that the findings herein would have a potential impact on fundamental chemistry and biology as many processes in nature involve the interplay of hydrophobic and hydrophilic groups.

  4. The hydrogen bond in the solid state.

    Science.gov (United States)

    Steiner, Thomas

    2002-01-04

    The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

  5. Traumatic Bonding: Clinical Implications in Incest.

    Science.gov (United States)

    deYoung, Mary; Lowry, Judith A.

    1992-01-01

    "Traumatic bonding" is defined as "the evolution of emotional dependency between...a child and an adult [in] a relationship characterized by periodic sexual abuse." Maintains that the concept holds promise for explaining confusing dynamics of incest. Demonstrates ways in which traumatic bonding can be applied to cases of incest…

  6. Theoretical exploration of pnicogen bond noncovalent interactions ...

    Indian Academy of Sciences (India)

    block-localized wave function (BLW) based energy decomposition scheme, Guan and Mo39 investigated thoroughly the pnicogen bond nature and the corre- sponding electron transfer in a series of substituted phosphines complexed with ammonia. Moreover, some novel pnicogen bond with special electronic structures.

  7. 21 CFR 1.97 - Bonds.

    Science.gov (United States)

    2010-04-01

    ... by the owner or consignee on the appropriate form of a customs single-entry or term bond, containing... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Bonds. 1.97 Section 1.97 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL GENERAL ENFORCEMENT REGULATIONS...

  8. Hydrogen bond dynamics in bulk alcohols

    Science.gov (United States)

    Shinokita, Keisuke; Cunha, Ana V.; Jansen, Thomas L. C.; Pshenichnikov, Maxim S.

    2015-06-01

    Hydrogen-bonded liquids play a significant role in numerous chemical and biological phenomena. In the past decade, impressive developments in multidimensional vibrational spectroscopy and combined molecular dynamics-quantum mechanical simulation have established many intriguing features of hydrogen bond dynamics in one of the fundamental solvents in nature, water. The next class of a hydrogen-bonded liquid—alcohols—has attracted much less attention. This is surprising given such important differences between water and alcohols as the imbalance between the number of hydrogen bonds, each molecule can accept (two) and donate (one) and the very presence of the hydrophobic group in alcohols. Here, we use polarization-resolved pump-probe and 2D infrared spectroscopy supported by extensive theoretical modeling to investigate hydrogen bond dynamics in methanol, ethanol, and isopropanol employing the OH stretching mode as a reporter. The sub-ps dynamics in alcohols are similar to those in water as they are determined by similar librational and hydrogen-bond stretch motions. However, lower density of hydrogen bond acceptors and donors in alcohols leads to the appearance of slow diffusion-controlled hydrogen bond exchange dynamics, which are essentially absent in water. We anticipate that the findings herein would have a potential impact on fundamental chemistry and biology as many processes in nature involve the interplay of hydrophobic and hydrophilic groups.

  9. Hydrogen Bonds and Life in the Universe.

    Science.gov (United States)

    Vladilo, Giovanni; Hassanali, Ali

    2018-01-03

    The scientific community is allocating more and more resources to space missions and astronomical observations dedicated to the search for life beyond Earth. This experimental endeavor needs to be backed by a theoretical framework aimed at defining universal criteria for the existence of life. With this aim in mind, we have explored which chemical and physical properties should be expected for life possibly different from the terrestrial one, but similarly sustained by genetic and catalytic molecules. We show that functional molecules performing genetic and catalytic tasks must feature a hierarchy of chemical interactions operating in distinct energy bands. Of all known chemical bonds and forces, only hydrogen bonds are able to mediate the directional interactions of lower energy that are needed for the operation of genetic and catalytic tasks. For this reason and because of the unique quantum properties of hydrogen bonding, the functional molecules involved in life processes are predicted to have extensive hydrogen-bonding capabilities. A molecular medium generating a hydrogen-bond network is probably essential to support the activity of the functional molecules. These hydrogen-bond requirements constrain the viability of hypothetical biochemistries alternative to the terrestrial one, provide thermal limits to life molecular processes, and offer a conceptual framework to define a transition from a "covalent-bond stage" to a "hydrogen-bond stage" in prebiotic chemistry.

  10. Measuring of bond. A comparative experimental research

    NARCIS (Netherlands)

    Pluijm, R. van der

    1996-01-01

    In the framework of European test methods for masonry a simple test method for bond has to be established. The described research, carried out at Eindhoven University of Technology, tried to contribute to the development of such a test method. In this perspective, the research was focused on bond

  11. Cohesive Fracture Study of a Bonded Coarse Silica Sand Aggregate Bond Interface Subjected to Mixed-Mode Bending Conditions

    Directory of Open Access Journals (Sweden)

    Donna Chen

    2013-12-01

    Full Text Available One of the primary objectives in the design of composite structures is the prevention of premature bond failure. Therefore, the characterization of cohesive behavior is an important field of study in structural engineering. Using fracture mechanics principles, the cohesive behavior of an epoxy bonded coarse silica sand aggregate bond interface is studied in this paper, with a focus on finding a general analytical form of idealizing its behavior when used in a specimen possessing asymmetric and inhomogeneous qualities. Two series of small-scale specimens were experimentally tested under mixed-mode bending (MMB conditions, where it was found that there was negligible influence exerted on the fracture energy of the interface due to changes in the mixed-mode ratio or initial crack length. Using finite element analysis (FEA methods, an appropriate bilinear traction-separation model was developed to both validate as well as obtain a set of consistent parameters applicable to all tested specimens. Comparison of the Global Method and the Local Method, used to obtain partitioned Mode I and Mode II fracture energy values from MMB specimens, were made, with the conclusion that both methods are adequate in the calculation of the total fracture energy though the Local Method should be used to obtain accurate partitioned Mode I and Mode II fracture energy values. Idealization of the bond interface using the cohesive parameters derived can be accurately achieved by the use of both contact interactions and cohesive elements in two-dimensional and three-dimensional FE models, though the results obtained using contact interactions would be expected to exhibit greater global stiffness.

  12. Effect of root canal filling techniques on the bond strength of epoxy resin-based sealers.

    Science.gov (United States)

    Rached-Júnior, Fuad Jacob Abi; Souza, Angélica Moreira; Macedo, Luciana Martins Domingues; Raucci-Neto, Walter; Baratto-Filho, Flares; Silva, Bruno Marques; Silva-Sousa, Yara Teresinha Corrêa

    2016-01-01

    The aim of this study was to evaluate the effects of different root canal filling techniques on the bond strength of epoxy resin-based sealers. Sixty single-rooted canines were prepared using ProTaper (F5) and divided into the following groups based on the root filling technique: Lateral Compaction (LC), Single Cone (SC), and Tagger Hybrid Technique (THT). The following subgroups (n = 10) were also created based on sealer material used: AH Plus and Sealer 26. Two-millimeter-thick slices were cut from all the root thirds and subjected to push-out test. Data (MPa) was analyzed using ANOVA and Tukey's test (α = 0.05). The push-out values were significantly affected by the sealer, filling technique, and root third (p < 0.05). AH Plus (1.37 ± 1.04) exhibited higher values than Sealer 26 (0.92 ± 0.51), while LC (1.80 ± 0.98) showed greater bond strength than THT (1.16 ± 0.50) and SC (0.92 ± 0.25). The cervical (1.45 ± 1.14) third exhibited higher bond strength, followed by the middle (1.20 ± 0.72) and apical (0.78 ± 0.33) thirds. AH Plus/LC (2.26 ± 1.15) exhibited the highest bond strength values, followed by AH Plus/THT (1.32 ± 0.61), Sealer 26/LC (1.34 ± 0.42), and Sealer 26/THT (1.00 ± 0.27). The lowest values were obtained with AH Plus/SC and Sealer 26/SC. Thus, it can be concluded that the filling technique affects the bond strength of sealers. LC was associated with higher bond strength between the material and intra-radicular dentine than THT and SC techniques.

  13. Cold pressure welding - the mechanisms governing bonding

    DEFF Research Database (Denmark)

    Bay, Niels

    1979-01-01

    Investigations of the bonding surface in scanning electron microscope after fracture confirm the mechanisms of bond formation in cold pressure welding to be: fracture of work-hardened surface layer, surface expansion increasing the area of virgin surface, extrusion of virgin material through cracks...... of the original surface layer, and establishment of real contact and bonding between virgin material. This implies that normal pressure as well as surface expansion are basic parameters governing the bond strength. Experimental investigations of pressure welding Al-Al under plane strain compression in a specially...... developed equipment allowing independent variation of normal pressure and surface expansion confirm this. Based upon a slip-line analysis of the extrusion through cracks of the surface layer and upon the establishment of real contact between virgin material, a theory for the bond strength as a function...

  14. 1 mil gold bond wire study.

    Energy Technology Data Exchange (ETDEWEB)

    Huff, Johnathon; McLean, Michael B.; Jenkins, Mark W.; Rutherford, Brian Milne

    2013-05-01

    In microcircuit fabrication, the diameter and length of a bond wire have been shown to both affect the current versus fusing time ratio of a bond wire as well as the gap length of the fused wire. This study investigated the impact of current level on the time-to-open and gap length of 1 mil by 60 mil gold bond wires. During the experiments, constant current was provided for a control set of bond wires for 250ms, 410ms and until the wire fused; non-destructively pull-tested wires for 250ms; and notched wires. The key findings were that as the current increases, the gap length increases and 73% of the bond wires will fuse at 1.8A, and 100% of the wires fuse at 1.9A within 60ms. Due to the limited scope of experiments and limited data analyzed, further investigation is encouraged to confirm these observations.

  15. Halogen bonding origin properties and applications

    Science.gov (United States)

    Hobza, Pavel

    2015-12-01

    σ-hole bonding represents an unusual and novel type of noncovalent interactions in which atom with σ- hole interacts with Lewis base such as an electronegative atom (oxygen, nitrogen, …) or aromatic systems. This bonding is of electrostatic nature since the σ-hole bears a positive charge. Dispersion energy forms equally important energy term what is due to the fact that two heavy atoms (e.g. halogen and oxygen) having high polarizability lie close together (the respective distance is typically shorter than the sum of van der Waals radii). Among different types of σ-hole bondings the halogen bonding is by far the most known but chalcogen and pnictogen bondings are important as well.

  16. Halogen bonding origin properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Hobza, Pavel [Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague (Czech Republic); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Palacky University, 77146 Olomouc (Czech Republic)

    2015-12-31

    σ-hole bonding represents an unusual and novel type of noncovalent interactions in which atom with σ- hole interacts with Lewis base such as an electronegative atom (oxygen, nitrogen, …) or aromatic systems. This bonding is of electrostatic nature since the σ-hole bears a positive charge. Dispersion energy forms equally important energy term what is due to the fact that two heavy atoms (e.g. halogen and oxygen) having high polarizability lie close together (the respective distance is typically shorter than the sum of van der Waals radii). Among different types of σ-hole bondings the halogen bonding is by far the most known but chalcogen and pnictogen bondings are important as well.

  17. PMMA to Polystyrene bonding for polymer based microfluidic systems

    KAUST Repository

    Fan, Yiqiang

    2013-03-29

    A thermal bonding technique for Poly (methylmethacrylate) (PMMA) to Polystyrene (PS) is presented in this paper. The PMMA to PS bonding was achieved using a thermocompression method, and the bonding strength was carefully characterized. The bonding temperature ranged from 110 to 125 C with a varying compression force, from 700 to 1,000 N (0.36-0.51 MPa). After the bonding process, two kinds of adhesion quantification methods were used to measure the bonding strength: the double cantilever beam method and the tensile stress method. The results show that the bonding strength increases with a rising bonding temperature and bonding force. The results also indicate that the bonding strength is independent of bonding time. A deep-UV surface treatment method was also provided in this paper to lower the bonding temperature and compression force. Finally, a PMMA to PS bonded microfluidic device was fabricated successfully. © 2013 Springer-Verlag Berlin Heidelberg.

  18. Probing the Conformational and Functional Consequences of Disulfide Bond Engineering in Growth Hormone by Hydrogen-Deuterium Exchange Mass Spectrometry Coupled to Electron Transfer Dissociation

    DEFF Research Database (Denmark)

    Seger, Signe T; Breinholt, Jens; Faber, Johan H

    2015-01-01

    Human growth hormone (hGH), and its receptor interaction, is essential for cell growth. To stabilize a flexible loop between helices 3 and 4, while retaining affinity for the hGH receptor, we have engineered a new hGH variant (Q84C/Y143C). Here, we employ hydrogen-deuterium exchange mass...... spectrometry (HDX-MS) to map the impact of the new disulfide bond on the conformational dynamics of this new hGH variant. Compared to wild type hGH, the variant exhibits reduced loop dynamics, indicating a stabilizing effect of the introduced disulfide bond. Furthermore, the disulfide bond exhibits longer...

  19. Non destructive evaluation of adhesively bonded carbon fiber reinforced composite lap joints with varied bond quality

    Science.gov (United States)

    Vijayakumar, R. L.; Bhat, M. R.; Murthy, C. R. L.

    2012-05-01

    Structural adhesive bonding is widely used to execute assemblies in automobile and aerospace structures. The quality and reliability of these bonded joints must be ensured during service. In this context non destructive evaluation of these bonded structures play an important role. Evaluation of adhesively bonded composite single lap shear joints has been attempted through experimental approach. Series of tests, non-destructive as well as destructive were performed on different sets of carbon fiber reinforced polymer (CFRP) composite lap joint specimens with varied bond quality. Details of the experimental investigations carried out and the outcome are presented in this paper.

  20. Relation between force constant and bond length for carbon—nitrogen bonds

    Science.gov (United States)

    Byler, D. Michael; Susi, Heino; Damert, William C.

    Using 25 accurately known bond-stretching force constants and bond lengths for 23 molecules, a relation of the form: F = 37.3 r -5.35 has been obtained for carbon—nitrogen bonds. The root-mean-square deviation between the force constant values reported in the literature and those calculated from the equation above is 4.09 %. Fourteen of the molecules studied have a rotational symmetry axis that coincides with the carbon-to-nitrogen bond. The remaining molecules have lower symmetry. The observed force constant—bond length relationship gives quite satisfactory results for both groups of molecules.