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Sample records for lengths bond angles

  1. Two Comments on Bond Angles

    Science.gov (United States)

    Glaister, P.

    1997-09-01

    Tetrahedral Bond Angle from Elementary Trigonometry The alternative approach of using the scalar (or dot) product of vectors enables the determination of the bond angle in a tetrahedral molecule in a simple way. There is, of course, an even more straightforward derivation suitable for students who are unfamiliar with vectors, or products thereof, but who do know some elementary trigonometry. The starting point is the figure showing triangle OAB. The point O is the center of a cube, and A and B are at opposite corners of a face of that cube in which fits a regular tetrahedron. The required bond angle alpha = AÔB; and using Pythagoras' theorem, AB = 2(square root 2) is the diagonal of a face of the cube. Hence from right-angled triangle OEB, tan(alpha/2) = (square root 2) and therefore alpha = 2tan-1(square root 2) is approx. 109° 28' (see Fig. 1).

  2. Bond-Length Distortions in Strained Semiconductor Alloys

    International Nuclear Information System (INIS)

    Woicik, J.C.; Pellegrino, J.G.; Steiner, B.; Miyano, K.E.; Bompadre, S.G.; Sorensen, L.B.; Lee, T.; Khalid, S.

    1997-01-01

    Extended x-ray absorption fine structure measurements performed at In-K edge have resolved the outstanding issue of bond-length strain in semiconductor-alloy heterostructures. We determine the In-As bond length to be 2.581±0.004 Angstrom in a buried, 213 Angstrom thick Ga 0.78 In 0.22 As layer grown coherently on GaAs(001). This bond length corresponds to a strain-induced contraction of 0.015±0.004 Angstrom relative to the In-As bond length in bulk Ga 1-x In x As of the same composition; it is consistent with a simple model which assumes a uniform bond-length distortion in the epilayer despite the inequivalent In-As and Ga-As bond lengths. copyright 1997 The American Physical Society

  3. The Golden ratio, ionic and atomic radii and bond lengths

    Czech Academy of Sciences Publication Activity Database

    Heyrovská, Rajalakshmi

    2005-01-01

    Roč. 103, 6-8 (2005), s. 877-882 ISSN 0026-8976 R&D Projects: GA MPO(CZ) 1H-PK/42 Institutional research plan: CEZ:AV0Z40400503 Keywords : Bohr radius * bond lengths * axial ratios Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.351, year: 2005

  4. Bond lengths and bond strengths in compounds of the 5f elements

    International Nuclear Information System (INIS)

    Zachariasen, W.H.

    1975-01-01

    The variation of bond length (D) with bond strength (S) in normal valence compounds of 3d, 4d, 5d-4f, and 6d-5f elements can be represented approximately as D(S)=D(0.5) F(S), where D(0.5) is a characteristic constant for a given bond and F(S) an empirical function which is the same for all bonds. A bond strength Ssub(ij)=ssub(ji) is assigned to the bond between atoms i and j such that Σsub(j) Ssub(ij)=vsub(i) and Σsub(i) Ssub(ij)=vsub(j), where vsub(i) and vsub(j) are the normal valences of the two atoms. The function F(S) decreases monotonically with increasing S, and is normalized to unity at S=0.5, so that the constant D(0.5) has the physical meaning of being the bond length adjusted to S=0.5. The method described above was used to interpret and systematize the experimental results on bond lengths in oxides, halides, and oxyhalides of the 5f elements. (U.S.)

  5. The extended variant of the bond valence-bond length correlation curve for boron(III)-oxygen bonds

    International Nuclear Information System (INIS)

    Sidey, Vasyl

    2015-01-01

    The extended variant of the bond valence (s)-bond length (r) correlation curve for boron(III)-oxygen bonds has been closely approximated using the three-parameter function s = [k/(r - l)] - m, where s is measured in valence units (vu), r is measured in Aa, k = 0.53 Aa.vu, l = 0.975(1) Aa and m = 0.32 vu. The function s = exp[(r 0 - r)/b] traditionally used in the modern bond valence model requires the separate set of the bond valence parameters (r 0 = 1.362 Aa; b = 0.23 Aa) in order to approximate the above s-r curve for the bonds shorter than ∝1.3 Aa.

  6. Origin of the X-Hal (Hal = Cl, Br) bond-length change in the halogen-bonded complexes.

    Science.gov (United States)

    Wang, Weizhou; Hobza, Pavel

    2008-05-01

    The origin of the X-Hal bond-length change in the halogen bond of the X-Hal...Y type has been investigated at the MP2(full)/6-311++G(d,p) level of theory using a natural bond orbital analysis, atoms in molecules procedure, and electrostatic potential fitting methods. Our results have clearly shown that various theories explaining the nature of the hydrogen bond cannot be applied to explain the origin of the X-Hal bond-length change in the halogen bond. We provide a new explanation for this change. The elongation of the X-Hal bond length is caused by the electron-density transfer to the X-Hal sigma* antibonding orbital. For the blue-shifting halogen bond, the electron-density transfer to the X-Hal sigma* antibonding orbital is only of minor importance; it is the electrostatic attractive interaction that causes the X-Hal bond contraction.

  7. Bond-length fluctuations in the copper oxide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B [Texas Materials Institute, ETC 9.102, University of Texas at Austin, Austin, TX 78712 (United States)

    2003-02-26

    Superconductivity in the copper oxides occurs at a crossover from localized to itinerant electronic behaviour, a transition that is first order. A spinodal phase segregation is normally accomplished by atomic diffusion; but where it occurs at too low a temperature for atomic diffusion, it may be realized by cooperative atomic displacements. Locally cooperative, fluctuating atomic displacements may stabilize a distinguishable phase lying between a localized-electron phase and a Fermi-liquid phase; this intermediate phase exhibits quantum-critical-point behaviour with strong electron-lattice interactions making charge transport vibronic. Ordering of the bond-length fluctuations at lower temperatures would normally stabilize a charge-density wave (CDW), which suppresses superconductivity. It is argued that in the copper oxide superconductors, crossover occurs at an optimal doping concentration for the formation of ordered two-electron/two-hole bosonic bags of spin S = 0 in a matrix of localized spins; the correlation bags contain two holes in a linear cluster of four copper centres ordered within alternate Cu-O-Cu rows of a CuO{sub 2} sheet. This ordering is optimal at a hole concentration per Cu atom of p {approx} 1/6, but it is not static. Hybridization of the vibronic electrons with the phonons that define long-range order of the fluctuating (Cu-O) bond lengths creates barely itinerant, vibronic quasiparticles of heavy mass. The heavy itinerant vibrons form Cooper pairs having a coherence length of the dimension of the bosonic bags. It is the hybridization of electrons and phonons that, it is suggested, stabilizes the superconductive state relative to a CDW state. (topical review)

  8. Comparison of axial lengths in occludable angle and angle-closure glaucoma-The Bhaktapur Glaucoma Study

    NARCIS (Netherlands)

    Thapa, S.S.; Paudyal, I.; Khanal, S.; Paudel, N.; van Rens, G.H.M.B.

    2011-01-01

    Purpose. To compare the anterior chamber depth (ACD) and axial length of eyes in a population-based sample among normal, occludable angle, and primary angle-closure glaucoma (PACG) groups. Methods. Totally, 3979 subjects from a population-based glaucoma prevalence study underwent complete ocular

  9. The Influences of Overlap Length, Bond Line Thickness and Pretreatmant on the Mechanical Properties of Adhesives : Focussing on Bonding Glass

    NARCIS (Netherlands)

    Vervloed, J.; Kwakernaak, A.; Poulis, H.

    2008-01-01

    This paper focuses on the influences of overlap length, bond line thickness and pretreatment on the mechanical properties of adhesive bonds. In order to determine the bond strength, lap shear tests were performed. The researched adhesives are a 2 component epoxy and MS polymer. The smallest overlap

  10. Performance of quantum Monte Carlo for calculating molecular bond lengths

    Energy Technology Data Exchange (ETDEWEB)

    Cleland, Deidre M., E-mail: deidre.cleland@csiro.au; Per, Manolo C., E-mail: manolo.per@csiro.au [CSIRO Virtual Nanoscience Laboratory, 343 Royal Parade, Parkville, Victoria 3052 (Australia)

    2016-03-28

    This work investigates the accuracy of real-space quantum Monte Carlo (QMC) methods for calculating molecular geometries. We present the equilibrium bond lengths of a test set of 30 diatomic molecules calculated using variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC) methods. The effect of different trial wavefunctions is investigated using single determinants constructed from Hartree-Fock (HF) and Density Functional Theory (DFT) orbitals with LDA, PBE, and B3LYP functionals, as well as small multi-configurational self-consistent field (MCSCF) multi-determinant expansions. When compared to experimental geometries, all DMC methods exhibit smaller mean-absolute deviations (MADs) than those given by HF, DFT, and MCSCF. The most accurate MAD of 3 ± 2 × 10{sup −3} Å is achieved using DMC with a small multi-determinant expansion. However, the more computationally efficient multi-determinant VMC method has a similar MAD of only 4.0 ± 0.9 × 10{sup −3} Å, suggesting that QMC forces calculated from the relatively simple VMC algorithm may often be sufficient for accurate molecular geometries.

  11. Studies of technetium chemistry. Pt.8. The regularities of the bond length and configuration of rhenium and technetium complexes in crystals

    International Nuclear Information System (INIS)

    Liu Guozheng; Liu Boli

    1995-01-01

    Some bond length regularities in MO 6 , MO-4, MX 5 α and MX 4 αβ moieties of technetium and rhenium compounds are summarized and rationalized by cavity model. The chemical properties of technetium and rhenium are so similar that their corresponding complexes have almost the same configuration and M-X bond lengths when they are in cavity-controlled state. Technetium and Rhenium combine preferably with N, O, F, S, Cl and Br when they are in higher oxidation states (>3), but preferably with P, Se etc. when they are in lower oxidation states ( 4 αβ is approximately constant; (2) the average M-X bond length of MX 6 varies moderately with the oxidation state of M; (3) the bond length of M-X trans to M-α in MX 5 α has a linear relationship with the angle

  12. Analysis of surface bond lengths reported for chemisorption on metal surfaces

    Science.gov (United States)

    Mitchell, K. A. R.

    1985-01-01

    A review is given of bond length information available from the techniques of surface crystallography (particularly with LEED, SEXAFS and photoelectron diffraction) for chemisorption on well-defined surfaces of metals (M). For adsorbed main-group atoms (X), measured X-M interatomic distances for 38 combinations of X and M have been assessed with a bond order-bond length relation in combination with the Schomaker-Stevenson approach for determining single-bond lengths. When the surface bond orders are fixed primarily by the valency of X, this approach appears to provide a simple framework for predicing X-M surface bond lengths. Further, in cases where agreement has been reached from different surface crystallographic techniques, this framework has the potential for assessing refinements to the surface bonding model (e.g. in determining the roles of the effective surface valency of M, and of coordinate bonding and supplementary π bonding between X and M). Preliminary comparisons of structural data are also given for molecular adsorption (CO and ethylidyne) and for the chemisorption of other metal atoms.

  13. Effects of setting angle and chord length on performance of four blades bionic wind turbine

    Science.gov (United States)

    Yang, Z. X.; Li, G. S.; Song, L.; Bai, Y. F.

    2017-11-01

    With the energy crisis and the increasing environmental pollution, more and more efforts have been made about wind power development. In this paper, a four blades bionic wind turbine was proposed, and the outline of wind turbine was constructed by the fitted curve. This paper attempted to research the effects of setting angle and chord length on performance of four blades bionic wind turbine by computational fluid dynamics (CFD) simulation. The results showed that the setting angle and chord length of the bionic wind turbine has some significant effects on the efficiency of the wind turbine, and within the range of wind speed from 7 m/s to 15 m/s, the wind turbine achieved maximum efficiency when the setting angle is 31 degree and the chord length is 125 mm. The conclusion will work as a guideline for the improvement of wind turbine design

  14. Charge transfer and bond lengths in YBa2Cu3-xMxO6+y

    International Nuclear Information System (INIS)

    Jorgensen, J.D.; Rhyne, J.J.; Neumann, D.A.; Miceli, P.F.; Tarascon, J.M.; Greene, L.H.; Barboux, P.

    1989-01-01

    We discuss the effects of doping on the Cu chain sites in YBa 2 Cu 3-x M x O 6+y . The relationship between bond lengths obtained from neutron scattering and charge transfer is evaluated in terms of bond valence. In particular, it is concluded that removing an oxygen from the chains transfers one electron to the planes. 24 refs., 3 figs

  15. Effect of Different Bar Embedment Length on Bond-Slip in Plain and Fiber Reinforced Concrete

    NARCIS (Netherlands)

    Jankovic, D.; Chopra, M.B.; Kunnath, S.K.

    2001-01-01

    This research aims to study the behaviour of the concrete-steel bond using numerical models, taking into account the effect of the different bar embedment length. Both plain and fiber reinforced concrete (FRC) are modeled. The interface bond stress as well as load-displacement response of the

  16. Bond length effects during the dissociation of O2 on Ni(1 1 1)

    International Nuclear Information System (INIS)

    Shuttleworth, I.G.

    2015-01-01

    Graphical abstract: - Highlights: • The dissociation of O 2 on Ni(1 1 1) has been investigated using the Nudged Elastic Band (NEB) technique. • An exceptional correlation has been identified between the O/Ni bond order and the O 2 bond length for a series of sterically different reaction paths. • Direct magnetic phenomena accompany these processes suggesting further mechanisms for experimental control. - Abstract: The interaction between O 2 and Ni(1 1 1) has been investigated using spin-polarised density functional theory. A series of low activation energy (E A = 103–315 meV) reaction pathways corresponding to precursor and non-precursor mediated adsorption have been identified. It has been seen that a predominantly pathway-independent correlation exists between O−Ni bond order and the O 2 bond length. This correlation demonstrates that the O−O interaction predominantly determines the bonding of this system

  17. Slack length of gastrocnemius medialis and Achilles tendon occurs at different ankle angles.

    Science.gov (United States)

    Hug, François; Lacourpaille, Lilian; Maïsetti, Olivier; Nordez, Antoine

    2013-09-27

    Although muscle-tendon slack length is a crucial parameter used in muscle models, this is one of the most difficult measures to estimate in vivo. The aim of this study was to determine the onset of the rise in tension (i.e., slack length) during passive stretching in both Achilles tendon and gastrocnemius medialis. Muscle and tendon shear elastic modulus was measured by elastography (supersonic shear imaging) during passive plantarflexion (0° and 90° of knee angle, 0° representing knee fully extended, in a random order) in 9 participants. The within-session repeatability of the determined slack length was good at 90° of knee flexion (SEM=3.3° and 2.2° for Achilles tendon and gastrocnemius medialis, respectively) and very good at 0° of knee flexion (SEM=1.9° and 1.9° for Achilles tendon and gastrocnemius medialis, respectively). The slack length of gastrocnemius medialis was obtained at a significantly lower plantarflexed angle than for Achilles tendon at both 0° (Pslack can be experimentally determined using supersonic shear imaging. The slack length of gastrocnemius medialis and Achilles tendon occurred at different joint angles. Although reporting this result is crucial to a better understanding of muscle-tendon interactions, further experimental investigations are required to explain this result. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Knee Angle and Stride Length in Association with Ball Speed in Youth Baseball Pitchers

    Directory of Open Access Journals (Sweden)

    Bart van Trigt

    2018-05-01

    Full Text Available The purpose of this study was to determine whether stride length and knee angle of the leading leg at foot contact, at the instant of maximal external rotation of the shoulder, and at ball release are associated with ball speed in elite youth baseball pitchers. In this study, fifty-two elite youth baseball pitchers (mean age 15.2 SD (standard deviation 1.7 years pitched ten fastballs. Data were collected with three high-speed video cameras at a frequency of 240 Hz. Stride length and knee angle of the leading leg were calculated at foot contact, maximal external rotation, and ball release. The associations between these kinematic variables and ball speed were separately determined using generalized estimating equations. Stride length as percentage of body height and knee angle at foot contact were not significantly associated with ball speed. However, knee angles at maximal external rotation and ball release were significantly associated with ball speed. Ball speed increased by 0.45 m/s (1 mph with an increase in knee extension of 18 degrees at maximal external rotation and 19.5 degrees at ball release. In conclusion, more knee extension of the leading leg at maximal external rotation and ball release is associated with higher ball speeds in elite youth baseball pitchers.

  19. Inter-tetrahedra bond angle of permanently densified silicas extracted from their Raman spectra

    International Nuclear Information System (INIS)

    Hehlen, B

    2010-01-01

    Relative Raman scattering intensities are obtained in three samples of vitreous silica of increasing density. The variation of the intensity upon densification is very different for bending and stretching modes. For the former we find a Raman coupling-to-light coefficient C B ∝ω 2 . A comparative intensity and frequency dependence of the Raman spectral lines in the three glasses is performed. Provided the Raman spectra are normalized by C B , there exists a simple relation between the Si-O-Si bond angle and the frequency of all O-bending motions, including those of fourfold (n = 4) and threefold (n = 3) rings. For 20% densification we find a reduction of ∼5.7 deg. of the maximum of the network angle distribution, a value in very close agreement with previous NMR experiments. The threefold and fourfold rings are weakly perturbed by the densification, with a bond angle reduction of ∼0.5 deg. for the former.

  20. Bond length contraction in Au nanocrystals formed by ion implantation into thin SiO2

    International Nuclear Information System (INIS)

    Kluth, P.; Johannessen, B.; Giraud, V.; Cheung, A.; Glover, C.J.; Azevedo, G. de M; Foran, G.J.; Ridgway, M.C.

    2004-01-01

    Au nanocrystals (NCs) fabricated by ion implantation into thin SiO 2 and annealing were investigated by means of extended x-ray absorption fine structure (EXAFS) spectroscopy and transmission electron microscopy. A bond length contraction was observed and can be explained by surface tension effects in a simple liquid-drop model. Such results are consistent with previous reports on nonembedded NCs implying a negligible influence of the SiO 2 matrix. Cumulant analysis of the EXAFS data suggests surface reconstruction or relaxation involving a further shortened bond length. A deviation from the octahedral closed shell structure is apparent for NCs of size 25 A

  1. Doping and bond length contributions to Mn K-edge shift in La1 ...

    Indian Academy of Sciences (India)

    ... corresponds to the shift in the center of gravity of the unoccupied Mn 4-band contributing to the Mn K-absorption edge region. This correspondence is then used to separate the doping and size contributions to the edge shift due to variation in the number of electrons in valence band and Mn-O bond lengths, respectively, ...

  2. Magnetic alloy nanowire arrays with different lengths: Insights into the crossover angle of magnetization reversal process

    Energy Technology Data Exchange (ETDEWEB)

    Samanifar, S.; Alikhani, M. [Department of Physics, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Almasi Kashi, M., E-mail: almac@kashanu.ac.ir [Department of Physics, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Ramazani, A. [Department of Physics, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of); Montazer, A.H. [Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan 87317-51167 (Iran, Islamic Republic of)

    2017-05-15

    Nanoscale magnetic alloy wires are being actively investigated, providing fundamental insights into tuning properties in magnetic data storage and processing technologies. However, previous studies give trivial information about the crossover angle of magnetization reversal process in alloy nanowires (NWs). Here, magnetic alloy NW arrays with different compositions, composed of Fe, Co and Ni have been electrochemically deposited into hard-anodic aluminum oxide templates with a pore diameter of approximately 150 nm. Under optimized conditions of alumina barrier layer and deposition bath concentrations, the resulting alloy NWs with aspect ratio and saturation magnetization (M{sub s}) up to 550 and 1900 emu cm{sup −3}, respectively, are systematically investigated in terms of composition, crystalline structure and magnetic properties. Using angular dependence of coercivity extracted from hysteresis loops, the reversal processes are evaluated, indicating non-monotonic behavior. The crossover angle (θ{sub c}) is found to depend on NW length and M{sub s}. At a constant M{sub s}, increasing NW length decreases θ{sub c}, thereby decreasing the involvement of vortex mode during the magnetization reversal process. On the other hand, decreasing M{sub s} decreases θ{sub c} in large aspect ratio (>300) alloy NWs. Phenomenologically, it is newly found that increasing Ni content in the composition decreases θ{sub c}. The angular first-order reversal curve (AFORC) measurements including the irreversibility of magnetization are also investigated to gain a more detailed insight into θ{sub c}. - Highlights: • Magnetic alloy NWs with aspect ratios up to 550 were fabricated into hard-AAO templates. • Morphology, composition, crystal structure and magnetic properties were investigated. • Angular dependence of coercivity was used to describe the magnetization reversal process. • The crossover angle of magnetization reversal was found to depend on NW length and M{sub s}.

  3. MRI Evaluation of Spinal Length and Vertebral Body Angle During Loading with a Spinal Compression Harness

    Science.gov (United States)

    Campbell, James A.; Hargens, Alan R.; Murthy, G.; Ballard, R. E.; Watenpaugh, D. E.; Hargens, Alan, R.; Sanchez, E.; Yang, C.; Mitsui, I.; Schwandt, D.; hide

    1998-01-01

    Weight bearing by the spinal column during upright posture often plays a role in the common problem of low back pain. Therefore, we developed a non-ferromagnetic spinal compression harness to enable MRI investigations of the spinal column during axial loading. Human subjects were fitted with a Nest and a footplate which were connected by adjustable straps to an analog load cell. MRI scans of human subjects (5 males and 1 female with age range of 27-53 yrs) during loaded and unloaded conditions were accomplished with a 1.5 Tesla GE Signa scanner. Studies of two subjects undergoing sequentially increasing spinal loads revealed significant decreases (r(sup 2) = 0.852) in spinal length between T4 and L5 culminating in a 1.5 to 2% length decrease during loading with 75% body weight. Sagittal vertebral body angles of four subjects placed under a constant 50% body weight load for one hour demonstrated increased lordotic and kyphotic curvatures. In the lumbar spine, the L2 vertebral body experienced the greatest angular change (-3 deg. to -5 deg.) in most subjects while in the thoracic spine, T4 angles increased from the unloaded state by +2 deg. to +9 deg. Overall, our studies demonstrate: 1) a progressive, although surprisingly small, decrease in spinal length with increasing load and 2) relatively large changes in spinal column angulation with 50% body weight.

  4. Scaling of the critical free length for progressive unfolding of self-bonded graphene

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, Kenny; Cranford, Steven W., E-mail: s.cranford@neu.edu [Laboratory of Nanotechnology in Civil Engineering (NICE), Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115 (United States)

    2014-05-19

    Like filled pasta, rolled or folded graphene can form a large nanocapsule surrounding a hollow interior. Use as a molecular carrier, however, requires understanding of the opening of such vessels. Here, we investigate a monolayer sheet of graphene as a theoretical trial platform for such a nanocapsule. The graphene is bonded to itself via aligned disulfide (S-S) bonds. Through theoretical analysis and atomistic modeling, we probe the critical nonbonded length (free length, L{sub crit}) that induces fracture-like progressive unfolding as a function of folding radius (R{sub i}). We show a clear linear scaling relationship between the length and radius, which can be used to determine the necessary bond density to predict mechanical opening/closing. However, stochastic dissipated energy limits any exact elastic formulation, and the required energy far exceeds the dissociation energy of the S-S bond. We account for the necessary dissipated kinetic energy through a simple scaling factor (Ω), which agrees well with computational results.

  5. Bond lengths in Cd1-xZnxTe beyond linear laws revisited

    International Nuclear Information System (INIS)

    Koteski, V.; Haas, H.; Holub-Krappe, E.; Ivanovic, N.; Mahnke, H.-E.

    2004-01-01

    We have investigated the development of local bond lengths with composition in the Cd 1-x Zn x Te mixed system by measuring the fine structure in X-ray absorption (EXAFS) at all three constituent atoms. The bond strength is found to dominate over the averaging of the bulk so that the local bond length deviates only slightly from its natural value determined for the pure binary components ZnTe and CdTe, respectively. The deviations are significantly less than predicted by a simple radial force constant model for tetrahedrally co-ordinated binary systems, and the bond-length variation with concentration is significantly non-linear. For the second shell, bimodal anion-anion distances are found while the cation-cation distances can already be described by the virtual crystal approximation. In the diluted regime close to the end-point compounds, we have complemented our experimental work by ab initio calculations based on density functional theory with the WIEN97 program using the linearised augmented plane wave method. Equilibrium atomic lattice positions have been calculated for the substitutional isovalent metal atom in a 32-atom super cell, Zn in the CdTe lattice or Cd in the ZnTe lattice, respectively, yielding good agreement with the atomic distances as determined in our EXAFS experiments

  6. Phi ({Phi}) and psi ({Psi}) angles involved in malarial peptide bonds determine sterile protective immunity

    Energy Technology Data Exchange (ETDEWEB)

    Patarroyo, Manuel E., E-mail: mepatarr@gmail.com [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Universidad Nacional de Colombia, Bogota (Colombia); Moreno-Vranich, Armando; Bermudez, Adriana [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia)

    2012-12-07

    Highlights: Black-Right-Pointing-Pointer Phi ({Phi}) and psi ({Psi}) angles determine sterile protective immunity. Black-Right-Pointing-Pointer Modified peptide's tendency to assume a regular conformation related to a PPII{sub L}. Black-Right-Pointing-Pointer Structural modifications in mHABPs induce Ab and protective immunity. Black-Right-Pointing-Pointer mHABP backbone atom's interaction with HLA-DR{beta}1{sup Asterisk-Operator} is stabilised by H-bonds. -- Abstract: Modified HABP (mHABP) regions interacting with HLA-DR{beta}1{sup Asterisk-Operator} molecules have a more restricted conformation and/or sequence than other mHABPs which do not fit perfectly into their peptide binding regions (PBR) and do not induce an acceptable immune response due to the critical role of their {Phi} and {Psi} torsion angles. These angle's critical role was determined in such highly immunogenic, protection-inducing response against experimental malaria using the conformers (mHABPs) obtained by {sup 1}H-NMR and superimposed into HLA-DR{beta}1{sup Asterisk-Operator }-like Aotus monkey molecules; their phi ({Phi}) and psi ({Psi}) angles were measured and the H-bond formation between these molecules was evaluated. The aforementioned mHABP propensity to assume a regular conformation similar to a left-handed polyproline type II helix (PPII{sub L}) led to suggesting that favouring these conformations according to their amino acid sequence would lead to high antibody titre production and sterile protective immunity induction against malaria, thereby adding new principles or rules for vaccine development, malaria being one of them.

  7. Do the angle and length of the eustachian tube influence the development of chronic otitis media?

    Science.gov (United States)

    Dinç, Aykut Erdem; Damar, Murat; Uğur, Mehmet Birol; Öz, Ibrahim Ilker; Eliçora, Sultan Şevik; Bişkin, Sultan; Tutar, Hakan

    2015-09-01

    To compare the eustachian tube (ET) angle (ETa) and length (ETl) of ears with and without chronic otitis media (COM), and to determine the relationship between ET anatomy and the development of COM. A retrospective case-control study. The study group comprised 125 patients (age range, 8-79 years; 64 males and 61 females) with 124 normal ears and 126 diseased ears, including ears with chronic suppurative otitis media (CSOM) with central perforation, intratympanic tympanosclerosis (ITTS), cholesteatoma, and a tympanic membrane with retraction pockets (TMRP). ET angle and length were measured using computed tomography employing the multiplanar reconstruction technique. The ETa was significantly more horizontal in diseased versus normal ears of all study groups (P = .030), and there was no group difference in ETl (P = .160). ETl was shorter in CSOM versus ITTS ears and normal ears (P = .007 and P = .003, respectively) and in cholesteatoma versus TMRP ears (P = .014). In the unilateral COM group, there were no significant differences in the ETa or ETl of diseased versus contralateral normal ears (P = .155 and P = .710, respectively). The ETa was significantly more horizontal in childhood-onset diseased versus normal ears (P = .027), and there was no group difference in ETl (P = .732). The ETa (P = .002) and ETl (P < .001) were significantly greater in males than females. A more horizontal ETa and shorter ETl could be contributory (though not significantly) etiological factors in the development of COM. 3b. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  8. Measurements of the microwave spectrum, Re-H bond length, and Re quadrupole coupling for HRe(CO)5

    Science.gov (United States)

    Kukolich, Stephen G.; Sickafoose, Shane M.

    1993-11-01

    Rotational transition frequencies for rhenium pentacarbonyl hydride were measured in the 4-10 GHz range using a Flygare-Balle type microwave spectrometer. The rotational constants and Re nuclear quadrupole coupling constants for the four isotopomers, (1) H187Re(CO)5, (2) H185Re(CO)5, (3) D187Re(CO)5, and (4) D185Re(CO)5, were obtained from the spectra. For the most common isotopomer, B(1)=818.5464(2) MHz and eq Q(187Re)=-900.13(3) MHz. The Re-H bond length (r0) determined by fitting the rotational constants is 1.80(1) Å. Although the Re atom is located at a site of near-octahedral symmetry, the quadrupole coupling is large due to the large Re nuclear moments. A 2.7% increase in Re quadrupole coupling was observed for D-substituted isotopomers, giving a rather large isotope effect on the quadrupole coupling. The Cax-Re-Ceq angle is 96(1)°, when all Re-C-O angles are constrained to 180°.

  9. Comparative study on direct and indirect bracket bonding techniques regarding time length and bracket detachment

    Directory of Open Access Journals (Sweden)

    Jefferson Vinicius Bozelli

    2013-12-01

    Full Text Available OBJECTIVE: The aim of this study was to assess the time spent for direct (DBB - direct bracket bonding and indirect (IBB - indirect bracket bonding bracket bonding techniques. The time length of laboratorial (IBB and clinical steps (DBB and IBB as well as the prevalence of loose bracket after a 24-week follow-up were evaluated. METHODS: Seventeen patients (7 men and 10 women with a mean age of 21 years, requiring orthodontic treatment were selected for this study. A total of 304 brackets were used (151 DBB and 153 IBB. The same bracket type and bonding material were used in both groups. Data were submitted to statistical analysis by Wilcoxon non-parametric test at 5% level of significance. RESULTS: Considering the total time length, the IBB technique was more time-consuming than the DBB (p < 0.001. However, considering only the clinical phase, the IBB took less time than the DBB (p < 0.001. There was no significant difference (p = 0.910 for the time spent during laboratorial positioning of the brackets and clinical session for IBB in comparison to the clinical procedure for DBB. Additionally, no difference was found as for the prevalence of loose bracket between both groups. CONCLUSION: the IBB can be suggested as a valid clinical procedure since the clinical session was faster and the total time spent for laboratorial positioning of the brackets and clinical procedure was similar to that of DBB. In addition, both approaches resulted in similar frequency of loose bracket.

  10. Phi (Φ) and psi (Ψ) angles involved in malarial peptide bonds determine sterile protective immunity.

    Science.gov (United States)

    Patarroyo, Manuel E; Moreno-Vranich, Armando; Bermúdez, Adriana

    2012-12-07

    Modified HABP (mHABP) regions interacting with HLA-DRβ1(∗) molecules have a more restricted conformation and/or sequence than other mHABPs which do not fit perfectly into their peptide binding regions (PBR) and do not induce an acceptable immune response due to the critical role of their Φ and Ψ torsion angles. These angle's critical role was determined in such highly immunogenic, protection-inducing response against experimental malaria using the conformers (mHABPs) obtained by (1)H-NMR and superimposed into HLA-DRβ1(∗)-like Aotus monkey molecules; their phi (Φ) and psi (Ψ) angles were measured and the H-bond formation between these molecules was evaluated. The aforementioned mHABP propensity to assume a regular conformation similar to a left-handed polyproline type II helix (PPII(L)) led to suggesting that favouring these conformations according to their amino acid sequence would lead to high antibody titre production and sterile protective immunity induction against malaria, thereby adding new principles or rules for vaccine development, malaria being one of them. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Non-destructive testing of full-length bonded rock bolts based on HHT signal analysis

    Science.gov (United States)

    Shi, Z. M.; Liu, L.; Peng, M.; Liu, C. C.; Tao, F. J.; Liu, C. S.

    2018-04-01

    Full-length bonded rock bolts are commonly used in mining, tunneling and slope engineering because of their simple design and resistance to corrosion. However, the length of a rock bolt and grouting quality do not often meet the required design standards in practice because of the concealment and complexity of bolt construction. Non-destructive testing is preferred when testing a rock bolt's quality because of the convenience, low cost and wide detection range. In this paper, a signal analysis method for the non-destructive sound wave testing of full-length bonded rock bolts is presented, which is based on the Hilbert-Huang transform (HHT). First, we introduce the HHT analysis method to calculate the bolt length and identify defect locations based on sound wave reflection test signals, which includes decomposing the test signal via empirical mode decomposition (EMD), selecting the intrinsic mode functions (IMF) using the Pearson Correlation Index (PCI) and calculating the instantaneous phase and frequency via the Hilbert transform (HT). Second, six model tests are conducted using different grouting defects and bolt protruding lengths to verify the effectiveness of the HHT analysis method. Lastly, the influence of the bolt protruding length on the test signal, identification of multiple reflections from defects, bolt end and protruding end, and mode mixing from EMD are discussed. The HHT analysis method can identify the bolt length and grouting defect locations from signals that contain noise at multiple reflected interfaces. The reflection from the long protruding end creates an irregular test signal with many frequency peaks on the spectrum. The reflections from defects barely change the original signal because they are low energy, which cannot be adequately resolved using existing methods. The HHT analysis method can identify reflections from the long protruding end of the bolt and multiple reflections from grouting defects based on mutations in the instantaneous

  12. Bond length variation in Zn substituted NiO studied from extended X-ray absorption fine structure

    Science.gov (United States)

    Singh, S. D.; Poswal, A. K.; Kamal, C.; Rajput, Parasmani; Chakrabarti, Aparna; Jha, S. N.; Ganguli, Tapas

    2017-06-01

    Bond length behavior for Zn substituted NiO is determined through extended x-ray absorption fine structure (EXAFS) measurements performed at ambient conditions. We report bond length value of 2.11±0.01 Å for Zn-O of rock salt (RS) symmetry, when Zn is doped in RS NiO. Bond length for Zn substituted NiO RS ternary solid solutions shows relaxed behavior for Zn-O bond, while it shows un-relaxed behavior for Ni-O bond. These observations are further supported by first-principles calculations. It is also inferred that Zn sublattice remains nearly unchanged with increase in lattice parameter. On the other hand, Ni sublattice dilates for Zn compositions up to 20% to accommodate increase in the lattice parameter. However, for Zn compositions more than 20%, it does not further dilate. It has been attributed to the large disorder that is incorporated in the system at and beyond 20% of Zn incorporation in the cubic RS lattice of ternary solid solutions. For these large percentages of Zn incorporation, the Ni and the Zn atoms re-arrange themselves microscopically about the same nominal bond length rather than systematically increase in magnitude to minimize the energy of the system. This results in an increase in the Debye-Waller factor with increase in the Zn concentration rather than a systematic increase in the bond lengths.

  13. Relation between frequency and H bond length in heavy water: Towards the understanding of the unusual properties of H bond dynamics in nanoporous media

    International Nuclear Information System (INIS)

    Pommeret, Stanislas; Leicknam, Jean-Claude; Bratos, Savo; Musat, Raluca; Renault, Jean Philippe

    2009-01-01

    The published work on H bond dynamics mainly refers to diluted solutions HDO/D 2 O rather than to normal water. The reasons for this choice are both theoretical and experimental. Mechanical isolation of the OH vibrator eliminating the resonant energy transfer makes it a better probe of the local H bond network, while the dilution in heavy water reduces the infrared absorption, which permits the use of thicker experimental cells. The isotopic substitution does not alter crucially the nature of the problem. The length r of an OH . . . O group is statistically distributed over a large interval comprised between 2.7 and 3.2 A with a mean value r 0 = 2.86 A. Liquid water may thus be viewed as a mixture of hydrogen bonds of different length. Two important characteristics of hydrogen bonding must be mentioned. (i) The OH stretching vibrations are strongly affected by this interaction. The shorter the length r of the hydrogen bond, the strongest the H bond link and the lower is its frequency ω: the covalent OH bond energy is lent to the OH. . .O bond and reinforces the latter. A number of useful relationships between ω and r were published to express this correlation. The one adopted in our previous work is the relationship due to Mikenda. (ii) Not only the OH vibrations, but also the HDO rotations are influenced noticeably by hydrogen bonding. This is due to steric forces that hinder the HDO rotations. As they are stronger in short than in long hydrogen bonds, rotations are slower in the first case than in the second. This effect was only recently discovered, but its existence is hardly to be contested. In the present contribution, we want to revisit the relationship between the frequency of the OH vibrator and the distance OH. . .O.

  14. Predicted bond length variation in wurtzite and zinc-blende InGaN and AlGaN alloys

    International Nuclear Information System (INIS)

    Mattila, T.; Zunger, A.

    1999-01-01

    Valence force field simulations utilizing large supercells are used to investigate the bond lengths in wurtzite and zinc-blende In x Ga 1-x N and Al x Ga 1-x N random alloys. We find that (i) while the first-neighbor cation endash anion shell is split into two distinct values in both wurtzite and zinc-blende alloys (R Ga-N 1 ≠R In-N 1 ), the second-neighbor cation endash anion bonds are equal (R Ga-N 2 =R In-N 2 ). (ii) The second-neighbor cation endash anion bonds exhibit a crucial difference between wurtzite and zinc-blende binary structures: in wurtzite we find two bond distances which differ in length by 13% while in the zinc-blende structure there is only one bond length. This splitting is preserved in the alloy, and acts as a fingerprint, distinguishing the wurtzite from the zinc-blende structure. (iii) The small splitting of the first-neighbor cation endash anion bonds in the wurtzite structure due to nonideal c/a ratio is preserved in the alloy, but is obscured by the bond length broadening. (iv) The cation endash cation bond lengths exhibit three distinct values in the alloy (Ga endash Ga, Ga endash In, and In endash In), while the anion endash anion bonds are split into two values corresponding to N endash Ga endash N and N endash In endash N. (v) The cation endash related splitting of the bonds and alloy broadening are considerably larger in InGaN alloy than in AlGaN alloy due to larger mismatch between the binary compounds. (vi) The calculated first-neighbor cation endash anion and cation endash cation bond lengths in In x Ga 1-x N alloy are in good agreement with the available experimental data. The remaining bond lengths are provided as predictions. In particular, the predicted splitting for the second-neighbor cation endash anion bonds in the wurtzite structure awaits experimental testing. copyright 1999 American Institute of Physics

  15. Models for mean bonding length, melting point and lattice thermal expansion of nanoparticle materials

    Energy Technology Data Exchange (ETDEWEB)

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.com [Department of Physics, College of Science, University of Salahaddin-Erbil, Arbil, Kurdistan (Iraq)

    2012-11-15

    Graphical abstract: Three models are derived to explain the nanoparticles size dependence of mean bonding length, melting temperature and lattice thermal expansion applied on Sn, Si and Au. The following figures are shown as an example for Sn nanoparticles indicates hilly applicable models for nanoparticles radius larger than 3 nm. Highlights: ► A model for a size dependent mean bonding length is derived. ► The size dependent melting point of nanoparticles is modified. ► The bulk model for lattice thermal expansion is successfully used on nanoparticles. -- Abstract: A model, based on the ratio number of surface atoms to that of its internal, is derived to calculate the size dependence of lattice volume of nanoscaled materials. The model is applied to Si, Sn and Au nanoparticles. For Si, that the lattice volume is increases from 20 Å{sup 3} for bulk to 57 Å{sup 3} for a 2 nm size nanocrystals. A model, for calculating melting point of nanoscaled materials, is modified by considering the effect of lattice volume. A good approach of calculating size-dependent melting point begins from the bulk state down to about 2 nm diameter nanoparticle. Both values of lattice volume and melting point obtained for nanosized materials are used to calculate lattice thermal expansion by using a formula applicable for tetrahedral semiconductors. Results for Si, change from 3.7 × 10{sup −6} K{sup −1} for a bulk crystal down to a minimum value of 0.1 × 10{sup −6} K{sup −1} for a 6 nm diameter nanoparticle.

  16. Models for mean bonding length, melting point and lattice thermal expansion of nanoparticle materials

    International Nuclear Information System (INIS)

    Omar, M.S.

    2012-01-01

    Graphical abstract: Three models are derived to explain the nanoparticles size dependence of mean bonding length, melting temperature and lattice thermal expansion applied on Sn, Si and Au. The following figures are shown as an example for Sn nanoparticles indicates hilly applicable models for nanoparticles radius larger than 3 nm. Highlights: ► A model for a size dependent mean bonding length is derived. ► The size dependent melting point of nanoparticles is modified. ► The bulk model for lattice thermal expansion is successfully used on nanoparticles. -- Abstract: A model, based on the ratio number of surface atoms to that of its internal, is derived to calculate the size dependence of lattice volume of nanoscaled materials. The model is applied to Si, Sn and Au nanoparticles. For Si, that the lattice volume is increases from 20 Å 3 for bulk to 57 Å 3 for a 2 nm size nanocrystals. A model, for calculating melting point of nanoscaled materials, is modified by considering the effect of lattice volume. A good approach of calculating size-dependent melting point begins from the bulk state down to about 2 nm diameter nanoparticle. Both values of lattice volume and melting point obtained for nanosized materials are used to calculate lattice thermal expansion by using a formula applicable for tetrahedral semiconductors. Results for Si, change from 3.7 × 10 −6 K −1 for a bulk crystal down to a minimum value of 0.1 × 10 −6 K −1 for a 6 nm diameter nanoparticle.

  17. Increased hallux angle in children and its association with insufficient length of footwear: A community based cross-sectional study

    Directory of Open Access Journals (Sweden)

    Kundi Michael

    2009-12-01

    Full Text Available Abstract Background Wearing shoes of insufficient length during childhood has often been cited as leading to deformities of the foot, particularly to the development of hallux valgus disorders. Until now, these assumptions have not been confirmed through scientific research. This study aims to investigate whether this association can be statistically proven, and if children who wear shoes of insufficient length actually do have a higher risk of a more pronounced lateral deviation of the hallux. Methods 858 pre-school children were included in the study. The study sample was stratified by sex, urban/rural areas and Austrian province. The hallux angle and the length of the feet were recorded. The inside length of the children's footwear (indoor shoes worn in pre-school and outdoor shoes were assessed. Personal data and different anthropometric measurements were taken. The risk of hallux valgus deviation was statistically tested by a stepwise logistic regression analysis and the relative risk (odds ratio for a hallux angle ≥ 4 degrees was calculated. Results Exact examinations of the hallux angle could be conducted on a total of 1,579 individual feet. Only 23.9% out of 1,579 feet presented a straight position of the great toe. The others were characterized by lateral deviations (valgus position at different degrees, equalling 10 degrees or greater in 14.2% of the children's feet. 88.8% of 808 children examined wore indoor footwear that was of insufficient length, and 69.4% of 812 children wore outdoor shoes that were too short. A significant relationship was observed between the lengthwise fit of the shoes and the hallux angle: the shorter the shoe, the higher the value of the hallux angle. The relative risk (odds ratio of a lateral hallux deviation of ≥ 4 degrees in children wearing shoes of insufficient length was significantly increased. Conclusions There is a significant relationship between the hallux angle in children and footwear that is

  18. Increased hallux angle in children and its association with insufficient length of footwear: A community based cross-sectional study

    Science.gov (United States)

    2009-01-01

    Background Wearing shoes of insufficient length during childhood has often been cited as leading to deformities of the foot, particularly to the development of hallux valgus disorders. Until now, these assumptions have not been confirmed through scientific research. This study aims to investigate whether this association can be statistically proven, and if children who wear shoes of insufficient length actually do have a higher risk of a more pronounced lateral deviation of the hallux. Methods 858 pre-school children were included in the study. The study sample was stratified by sex, urban/rural areas and Austrian province. The hallux angle and the length of the feet were recorded. The inside length of the children's footwear (indoor shoes worn in pre-school and outdoor shoes) were assessed. Personal data and different anthropometric measurements were taken. The risk of hallux valgus deviation was statistically tested by a stepwise logistic regression analysis and the relative risk (odds ratio) for a hallux angle ≥ 4 degrees was calculated. Results Exact examinations of the hallux angle could be conducted on a total of 1,579 individual feet. Only 23.9% out of 1,579 feet presented a straight position of the great toe. The others were characterized by lateral deviations (valgus position) at different degrees, equalling 10 degrees or greater in 14.2% of the children's feet. 88.8% of 808 children examined wore indoor footwear that was of insufficient length, and 69.4% of 812 children wore outdoor shoes that were too short. A significant relationship was observed between the lengthwise fit of the shoes and the hallux angle: the shorter the shoe, the higher the value of the hallux angle. The relative risk (odds ratio) of a lateral hallux deviation of ≥ 4 degrees in children wearing shoes of insufficient length was significantly increased. Conclusions There is a significant relationship between the hallux angle in children and footwear that is too short in length. The

  19. Bite angle effects of diphosphines in C-C and C-X bond forming cross coupling reactions

    NARCIS (Netherlands)

    Birkholz, M.N.; Freixa, Z.; van Leeuwen, P.W.N.M.

    2009-01-01

    Catalytic reactions of C-C and C-X bond formation are discussed in this critical review with particular emphasis on cross coupling reactions catalyzed by palladium and wide bite angle bidentate diphosphine ligands. Especially those studies have been collected that allow comparison of the ligand bite

  20. Dependence of the length of the hydrogen bond on the covalent and cationic radii of hydrogen, and additivity of bonding distances

    Czech Academy of Sciences Publication Activity Database

    Heyrovská, Raji

    2006-01-01

    Roč. 432, č. 1-3 (2006), s. 348-351 ISSN 0009-2614 R&D Projects: GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507 Keywords : length of the hydrogen bond * ionic radius * Golden ratio Subject RIV: BO - Biophysics Impact factor: 2.462, year: 2006

  1. Incorporation of Hydrogen Bond Angle Dependency into the Generalized Solvation Free Energy Density Model.

    Science.gov (United States)

    Ma, Songling; Hwang, Sungbo; Lee, Sehan; Acree, William E; No, Kyoung Tai

    2018-04-23

    To describe the physically realistic solvation free energy surface of a molecule in a solvent, a generalized version of the solvation free energy density (G-SFED) calculation method has been developed. In the G-SFED model, the contribution from the hydrogen bond (HB) between a solute and a solvent to the solvation free energy was calculated as the product of the acidity of the donor and the basicity of the acceptor of an HB pair. The acidity and basicity parameters of a solute were derived using the summation of acidities and basicities of the respective acidic and basic functional groups of the solute, and that of the solvent was experimentally determined. Although the contribution of HBs to the solvation free energy could be evenly distributed to grid points on the surface of a molecule, the G-SFED model was still inadequate to describe the angle dependency of the HB of a solute with a polarizable continuum solvent. To overcome this shortcoming of the G-SFED model, the contribution of HBs was formulated using the geometric parameters of the grid points described in the HB coordinate system of the solute. We propose an HB angle dependency incorporated into the G-SFED model, i.e., the G-SFED-HB model, where the angular-dependent acidity and basicity densities are defined and parametrized with experimental data. The G-SFED-HB model was then applied to calculate the solvation free energies of organic molecules in water, various alcohols and ethers, and the log P values of diverse organic molecules, including peptides and a protein. Both the G-SFED model and the G-SFED-HB model reproduced the experimental solvation free energies with similar accuracy, whereas the distributions of the SFED on the molecular surface calculated by the G-SFED and G-SFED-HB models were quite different, especially for molecules having HB donors or acceptors. Since the angle dependency of HBs was included in the G-SFED-HB model, the SFED distribution of the G-SFED-HB model is well described

  2. Origin of the X-Hal (Hal ) Cl, Br) Bond-Length Change in the Halogen-Bonded Complexes

    Czech Academy of Sciences Publication Activity Database

    Wang, Weizhou; Hobza, Pavel

    2008-01-01

    Roč. 112, č. 17 (2008), s. 4114-4119 ISSN 1089-5639 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550510 Institutional research plan: CEZ:AV0Z40550506 Keywords : hal ogen bonded complexes * MP2(full)/6-311++G(d,p) method * natural bond orbital analysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.871, year: 2008

  3. Determination of Hydrogen Bond Structure in Water versus Aprotic Environments To Test the Relationship Between Length and Stability.

    Science.gov (United States)

    Sigala, Paul A; Ruben, Eliza A; Liu, Corey W; Piccoli, Paula M B; Hohenstein, Edward G; Martínez, Todd J; Schultz, Arthur J; Herschlag, Daniel

    2015-05-06

    Hydrogen bonds profoundly influence the architecture and activity of biological macromolecules. Deep appreciation of hydrogen bond contributions to biomolecular function thus requires a detailed understanding of hydrogen bond structure and energetics and the relationship between these properties. Hydrogen bond formation energies (ΔGf) are enormously more favorable in aprotic solvents than in water, and two classes of contributing factors have been proposed to explain this energetic difference, focusing respectively on the isolated and hydrogen-bonded species: (I) water stabilizes the dissociated donor and acceptor groups much better than aprotic solvents, thereby reducing the driving force for hydrogen bond formation; and (II) water lengthens hydrogen bonds compared to aprotic environments, thereby decreasing the potential energy within the hydrogen bond. Each model has been proposed to provide a dominant contribution to ΔGf, but incisive tests that distinguish the importance of these contributions are lacking. Here we directly test the structural basis of model II. Neutron crystallography, NMR spectroscopy, and quantum mechanical calculations demonstrate that O-H···O hydrogen bonds in crystals, chloroform, acetone, and water have nearly identical lengths and very similar potential energy surfaces despite ΔGf differences >8 kcal/mol across these solvents. These results rule out a substantial contribution from solvent-dependent differences in hydrogen bond structure and potential energy after association (model II) and thus support the conclusion that differences in hydrogen bond ΔGf are predominantly determined by solvent interactions with the dissociated groups (model I). These findings advance our understanding of universal hydrogen-bonding interactions and have important implications for biology and engineering.

  4. Validation of hamstrings musculoskeletal modeling by calculating peak hamstrings length at different hip angles

    NARCIS (Netherlands)

    van der Krogt, M.M.; Doorenbosch, C.A.M.; Harlaar, J.

    2008-01-01

    Accurate estimates of hamstrings lengths are useful, for example, to facilitate planning for surgical lengthening of the hamstrings in patients with cerebral palsy. In this study, three models used to estimate hamstrings length (M1: Delp, M2: Klein Horsman, M3: Hawkins and Hull) were evaluated. This

  5. Investigation of field corrosion performance and bond/development length of galvanized reinforcing steel.

    Science.gov (United States)

    2014-12-01

    In reinforced concrete systems, ensuring that a good bond between the concrete and the embedded reinforcing steel is critical to : long-term structural performance. Without good bond between the two, the system simply cannot behave as intended. The b...

  6. The determinants of bond angle variability in protein/peptide backbones: A comprehensive statistical/quantum mechanics analysis.

    Science.gov (United States)

    Improta, Roberto; Vitagliano, Luigi; Esposito, Luciana

    2015-11-01

    The elucidation of the mutual influence between peptide bond geometry and local conformation has important implications for protein structure refinement, validation, and prediction. To gain insights into the structural determinants and the energetic contributions associated with protein/peptide backbone plasticity, we here report an extensive analysis of the variability of the peptide bond angles by combining statistical analyses of protein structures and quantum mechanics calculations on small model peptide systems. Our analyses demonstrate that all the backbone bond angles strongly depend on the peptide conformation and unveil the existence of regular trends as function of ψ and/or φ. The excellent agreement of the quantum mechanics calculations with the statistical surveys of protein structures validates the computational scheme here employed and demonstrates that the valence geometry of protein/peptide backbone is primarily dictated by local interactions. Notably, for the first time we show that the position of the H(α) hydrogen atom, which is an important parameter in NMR structural studies, is also dependent on the local conformation. Most of the trends observed may be satisfactorily explained by invoking steric repulsive interactions; in some specific cases the valence bond variability is also influenced by hydrogen-bond like interactions. Moreover, we can provide a reliable estimate of the energies involved in the interplay between geometry and conformations. © 2015 Wiley Periodicals, Inc.

  7. Angle-Beam Shear Wave Scattering from Buried Crack-like Defects in Bonded Specimens (Postprint)

    Science.gov (United States)

    2017-02-01

    defects: such as understanding the scattering behavior of fatigue cracks emanating from fastener holes in aluminum structural components [2]. Angle...Ultrasonic NDE techniques using angle-beam wedges coupled to PZT transducers have also been utilized in measuring the depth of surface-breaking cracks

  8. Determination by vibrational spectra of the strength and the bond length of atoms U and O in uranyl complexes

    International Nuclear Information System (INIS)

    Rodriguez S, A.; Martinez Q, E.

    1996-01-01

    The vibrational spectra of different uranyl compounds were studied. The wave number was related to the harmonic oscillator model and to the mathematical expression of Badger as modified by Jones, to determine the strength and the bond length of atoms U and O in UO 2 2+ . A mathematical simplification develop by us is proposed and its results compared with values obtained by other methods. (Author)

  9. Ligand Bridging-Angle-Driven Assembly of Molecular Architectures Based on Quadruply Bonded Mo-Mo Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian-Rong; Yakovenko, Andrey A; Lu, Weigang; Timmons, Daren J; Zhuang, Wenjuan; Yuan, Daqiang; Zhou, Hong-Cai

    2010-12-15

    A systematic exploration of the assembly of Mo₂(O₂C-)₄-based metal–organic molecular architectures structurally controlled by the bridging angles of rigid organic linkers has been performed. Twelve bridging dicarboxylate ligands were designed to be of different sizes with bridging angles of 0, 60, 90, and 120° while incorporating a variety of nonbridging functional groups, and these ligands were used as linkers. These dicarboxylate linkers assemble with quadruply bonded Mo–Mo clusters acting as nodes to give 13 molecular architectures, termed metal–organic polygons/polyhedra with metal cluster node arrangements of a linear shape, triangle, octahedron, and cuboctahedron/anti-cuboctahedron. The syntheses of these complexes have been optimized and their structures determined by single-crystal X-ray diffraction. The results have shown that the shape and size of the resulting molecular architecture can be controlled by tuning the bridging angle and size of the linker, respectively. Functionalization of the linker can adjust the solubility of the ensuing molecular assembly but has little or no effect on the geometry of the product. Preliminary gas adsorption, spectroscopic, and electrochemical properties of selected members were also studied. The present work is trying to enrich metal-containing supramolecular chemistry through the inclusion of well-characterized quadruply bonded Mo–Mo units into the structures, which can widen the prospect of additional electronic functionality, thereby leading to novel properties.

  10. Ligand bridging-angle-driven assembly of molecular architectures based on quadruply bonded Mo-Mo dimers.

    Science.gov (United States)

    Li, Jian-Rong; Yakovenko, Andrey A; Lu, Weigang; Timmons, Daren J; Zhuang, Wenjuan; Yuan, Daqiang; Zhou, Hong-Cai

    2010-12-15

    A systematic exploration of the assembly of Mo2(O2C-)4-based metal-organic molecular architectures structurally controlled by the bridging angles of rigid organic linkers has been performed. Twelve bridging dicarboxylate ligands were designed to be of different sizes with bridging angles of 0, 60, 90, and 120° while incorporating a variety of nonbridging functional groups, and these ligands were used as linkers. These dicarboxylate linkers assemble with quadruply bonded Mo-Mo clusters acting as nodes to give 13 molecular architectures, termed metal-organic polygons/polyhedra with metal cluster node arrangements of a linear shape, triangle, octahedron, and cuboctahedron/anti-cuboctahedron. The syntheses of these complexes have been optimized and their structures determined by single-crystal X-ray diffraction. The results have shown that the shape and size of the resulting molecular architecture can be controlled by tuning the bridging angle and size of the linker, respectively. Functionalization of the linker can adjust the solubility of the ensuing molecular assembly but has little or no effect on the geometry of the product. Preliminary gas adsorption, spectroscopic, and electrochemical properties of selected members were also studied. The present work is trying to enrich metal-containing supramolecular chemistry through the inclusion of well-characterized quadruply bonded Mo-Mo units into the structures, which can widen the prospect of additional electronic functionality, thereby leading to novel properties.

  11. Distinguishing the Effects of Bond-Length Alternation versus Bond-Order Alternation on the Nonlinear Optical Properties of π-Conjugated Chromophores

    KAUST Repository

    Gieseking, Rebecca L.; Risko, Chad; Bredas, Jean-Luc

    2015-01-01

    Understanding the relationships between the molecular nonlinear optical (NLO) properties and the bond-length alternation (BLA) or π-bond-order alternation (BOA) along the molecular backbone of linear π-conjugated systems has proven widely useful in the development of NLO organic chromophores and materials. Here, we examine model polymethines to elucidate the reliability of these relationships. While BLA is solely a measure of molecular geometric structure, BOA includes information pertaining to the electronic structure. As a result, BLA is found to be a good predictor of NLO properties only when optimized geometries are considered, whereas BOA is more broadly applicable. Proper understanding of the distinction between BLA and BOA is critical when designing computational studies of NLO properties, especially for molecules in complex environments or in nonequilibrium geometries. © 2015 American Chemical Society.

  12. Distinguishing the Effects of Bond-Length Alternation versus Bond-Order Alternation on the Nonlinear Optical Properties of π-Conjugated Chromophores

    KAUST Repository

    Gieseking, Rebecca L.

    2015-06-18

    Understanding the relationships between the molecular nonlinear optical (NLO) properties and the bond-length alternation (BLA) or π-bond-order alternation (BOA) along the molecular backbone of linear π-conjugated systems has proven widely useful in the development of NLO organic chromophores and materials. Here, we examine model polymethines to elucidate the reliability of these relationships. While BLA is solely a measure of molecular geometric structure, BOA includes information pertaining to the electronic structure. As a result, BLA is found to be a good predictor of NLO properties only when optimized geometries are considered, whereas BOA is more broadly applicable. Proper understanding of the distinction between BLA and BOA is critical when designing computational studies of NLO properties, especially for molecules in complex environments or in nonequilibrium geometries. © 2015 American Chemical Society.

  13. Si-O-Si bond-angle distribution in vitreous silica from first-principles 29Si NMR analysis

    International Nuclear Information System (INIS)

    Mauri, Francesco; Pasquarello, Alfredo; Pfrommer, Bernd G.; Yoon, Young-Gui; Louie, Steven G.

    2000-01-01

    The correlation between 29 Si chemical shifts and Si-O-Si bond angles in SiO 2 is determined within density-functional theory for the full range of angles present in vitreous silica. This relation closely reproduces measured shifts of crystalline polymorphs. The knowledge of the correlation allows us to reliably extract from the experimental NMR spectrum the mean (151 degree sign ) and the standard deviation (11 degree sign ) of the Si-O-Si angular distribution of vitreous silica. In particular, we show that the Mozzi-Warren Si-O-Si angular distribution is not consistent with the NMR data. This analysis illustrates the potential of our approach for structural determinations of silicate glasses. (c) 2000 The American Physical Society

  14. Effects of Inclined Treadmill Walking on Pelvic Anterior Tilt Angle, Hamstring Muscle Length, and Trunk Muscle Endurance of Seated Workers with Flat-back Syndrome

    OpenAIRE

    Kim, Min-hee; Yoo, Won-gyu

    2014-01-01

    [Purpose] This study investigated the effects of inclined treadmill walking on pelvic anterior tilt angle, hamstring muscle length, and back muscle endurance of seated workers with flat-back syndrome. [Subjects] Eight seated workers with flat-back syndrome who complained of low-back pain in the L3–5 region participated in this study. [Methods] The subjects performed a walking exercise on a 30° inclined treadmill. We measured the pelvic anterior tilt angle, hamstring muscle length, and back mu...

  15. Internal-strain effect on the valence band of strained silicon and its correlation with the bond angles

    Energy Technology Data Exchange (ETDEWEB)

    Inaoka, Takeshi, E-mail: inaoka@phys.u-ryukyu.ac.jp; Yanagisawa, Susumu; Kadekawa, Yukihiro [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213 (Japan)

    2014-02-14

    By means of the first-principles density-functional theory, we investigate the effect of relative atom displacement in the crystal unit cell, namely, internal strain on the valence-band dispersion of strained silicon, and find close correlation of this effect with variation in the specific bond angles due to internal strain. We consider the [111] ([110]) band dispersion for (111) ((110)) biaxial tensility and [111] ([110]) uniaxial compression, because remarkably small values of hole effective mass m* can be obtained in this dispersion. Under the practical condition of no normal stress, biaxial tensility (uniaxial compression) involves additional normal compression (tensility) and internal strain. With an increase in the internal-strain parameter, the energy separation between the highest and second-highest valence bands becomes strikingly larger, and the highest band with conspicuously small m* extends remarkably down to a lower energy region, until it intersects or becomes admixed with the second band. This is closely correlated with the change in the specific bond angles, and this change can reasonably explain the above enlargement of the band separation.

  16. σ-Bond Electron Delocalization in Oligosilanes as Function of Substitution Pattern, Chain Length, and Spatial Orientation

    Directory of Open Access Journals (Sweden)

    Johann Hlina

    2016-08-01

    Full Text Available Polysilanes are known to exhibit the interesting property of σ-bond electron delocalization. By employing optical spectroscopy (UV-vis, it is possible to judge the degree of delocalization and also differentiate parts of the molecules which are conjugated or not. The current study compares oligosilanes of similar chain length but different substitution pattern. The size of the substituents determines the spatial orientation of the main chain and also controls the conformational flexibility. The chemical nature of the substituents affects the orbital energies of the molecules and thus the positions of the absorption bands.

  17. Correlation between protein secondary structure, backbone bond angles, and side-chain orientations

    Science.gov (United States)

    Lundgren, Martin; Niemi, Antti J.

    2012-08-01

    We investigate the fine structure of the sp3 hybridized covalent bond geometry that governs the tetrahedral architecture around the central Cα carbon of a protein backbone, and for this we develop new visualization techniques to analyze high-resolution x-ray structures in the Protein Data Bank. We observe that there is a correlation between the deformations of the ideal tetrahedral symmetry and the local secondary structure of the protein. We propose a universal coarse-grained energy function to describe the ensuing side-chain geometry in terms of the Cβ carbon orientations. The energy function can model the side-chain geometry with a subatomic precision. As an example we construct the Cα-Cβ structure of HP35 chicken villin headpiece. We obtain a configuration that deviates less than 0.4 Å in root-mean-square distance from the experimental x-ray structure.

  18. Bond-length strain in buried Ga1-xInxAs thin-alloy films grown coherently on InP(001)

    International Nuclear Information System (INIS)

    Woicik, J.C.; Gupta, J.A.; Watkins, S.P.; Crozier, E.D.

    1998-01-01

    The bond lengths in a series of strained, buried Ga 1-x In x As thin-alloy films grown coherently on InP(001) have been determined by high-resolution extended x-ray absorption fine-structure measurements. Comparison with a random-cluster calculation demonstrates that the external in-plane epitaxial strain imposed by pseudomorphic growth opposes the natural bond-length distortions due to alloying.copyright 1998 American Institute of Physics

  19. Effects of Inclined Treadmill Walking on Pelvic Anterior Tilt Angle, Hamstring Muscle Length, and Trunk Muscle Endurance of Seated Workers with Flat-back Syndrome.

    Science.gov (United States)

    Kim, Min-Hee; Yoo, Won-Gyu

    2014-06-01

    [Purpose] This study investigated the effects of inclined treadmill walking on pelvic anterior tilt angle, hamstring muscle length, and back muscle endurance of seated workers with flat-back syndrome. [Subjects] Eight seated workers with flat-back syndrome who complained of low-back pain in the L3-5 region participated in this study. [Methods] The subjects performed a walking exercise on a 30° inclined treadmill. We measured the pelvic anterior tilt angle, hamstring muscle length, and back muscle endurance before and after inclined treadmill walking. [Results] Anterior pelvic tilt angle and active knee extension angle significantly increased after inclined treadmill walking. Trunk extensor and flexor muscle endurance times were also significantly increased compared to the baseline. [Conclusion] Inclined treadmill walking may be an effective approach for the prevention or treatment of low-back pain in flat-back syndrome.

  20. Correcting for the free energy costs of bond or angle constraints in molecular dynamics simulations.

    Science.gov (United States)

    König, Gerhard; Brooks, Bernard R

    2015-05-01

    Free energy simulations are an important tool in the arsenal of computational biophysics, allowing the calculation of thermodynamic properties of binding or enzymatic reactions. This paper introduces methods to increase the accuracy and precision of free energy calculations by calculating the free energy costs of constraints during post-processing. The primary purpose of employing constraints for these free energy methods is to increase the phase space overlap between ensembles, which is required for accuracy and convergence. The free energy costs of applying or removing constraints are calculated as additional explicit steps in the free energy cycle. The new techniques focus on hard degrees of freedom and use both gradients and Hessian estimation. Enthalpy, vibrational entropy, and Jacobian free energy terms are considered. We demonstrate the utility of this method with simple classical systems involving harmonic and anharmonic oscillators, four-atomic benchmark systems, an alchemical mutation of ethane to methanol, and free energy simulations between alanine and serine. The errors for the analytical test cases are all below 0.0007kcal/mol, and the accuracy of the free energy results of ethane to methanol is improved from 0.15 to 0.04kcal/mol. For the alanine to serine case, the phase space overlaps of the unconstrained simulations range between 0.15 and 0.9%. The introduction of constraints increases the overlap up to 2.05%. On average, the overlap increases by 94% relative to the unconstrained value and precision is doubled. The approach reduces errors arising from constraints by about an order of magnitude. Free energy simulations benefit from the use of constraints through enhanced convergence and higher precision. The primary utility of this approach is to calculate free energies for systems with disparate energy surfaces and bonded terms, especially in multi-scale molecular mechanics/quantum mechanics simulations. This article is part of a Special Issue

  1. Low-power grating detection system chip for high-speed low-cost length and angle precision measurement

    Science.gov (United States)

    Hou, Ligang; Luo, Rengui; Wu, Wuchen

    2006-11-01

    This paper forwards a low power grating detection chip (EYAS) on length and angle precision measurement. Traditional grating detection method, such as resister chain divide or phase locked divide circuit are difficult to design and tune. The need of an additional CPU for control and display makes these methods' implementation more complex and costly. Traditional methods also suffer low sampling speed for the complex divide circuit scheme and CPU software compensation. EYAS is an application specific integrated circuit (ASIC). It integrates micro controller unit (MCU), power management unit (PMU), LCD controller, Keyboard interface, grating detection unit and other peripherals. Working at 10MHz, EYAS can afford 5MHz internal sampling rate and can handle 1.25MHz orthogonal signal from grating sensor. With a simple control interface by keyboard, sensor parameter, data processing and system working mode can be configured. Two LCD controllers can adapt to dot array LCD or segment bit LCD, which comprised output interface. PMU alters system between working and standby mode by clock gating technique to save power. EYAS in test mode (system action are more frequently than real world use) consumes 0.9mw, while 0.2mw in real world use. EYAS achieved the whole grating detection system function, high-speed orthogonal signal handling in a single chip with very low power consumption.

  2. The accuracy of molecular bond lengths computed by multireference electronic structure methods

    International Nuclear Information System (INIS)

    Shepard, Ron; Kedziora, Gary S.; Lischka, Hans; Shavitt, Isaiah; Mueller, Thomas; Szalay, Peter G.; Kallay, Mihaly; Seth, Michael

    2008-01-01

    We compare experimental R e values with computed R e values for 20 molecules using three multireference electronic structure methods, MCSCF, MR-SDCI, and MR-AQCC. Three correlation-consistent orbital basis sets are used, along with complete basis set extrapolations, for all of the molecules. These data complement those computed previously with single-reference methods. Several trends are observed. The SCF R e values tend to be shorter than the experimental values, and the MCSCF values tend to be longer than the experimental values. We attribute these trends to the ionic contamination of the SCF wave function and to the corresponding systematic distortion of the potential energy curve. For the individual bonds, the MR-SDCI R e values tend to be shorter than the MR-AQCC values, which in turn tend to be shorter than the MCSCF values. Compared to the previous single-reference results, the MCSCF values are roughly comparable to the MP4 and CCSD methods, which are more accurate than might be expected due to the fact that these MCSCF wave functions include no extra-valence electron correlation effects. This suggests that static valence correlation effects, such as near-degeneracies and the ability to dissociate correctly to neutral fragments, play an important role in determining the shape of the potential energy surface, even near equilibrium structures. The MR-SDCI and MR-AQCC methods predict R e values with an accuracy comparable to, or better than, the best single-reference methods (MP4, CCSD, and CCSD(T)), despite the fact that triple and higher excitations into the extra-valence orbital space are included in the single-reference methods but are absent in the multireference wave functions. The computed R e values using the multireference methods tend to be smooth and monotonic with basis set improvement. The molecular structures are optimized using analytic energy gradients, and the timings for these calculations show the practical advantage of using variational wave

  3. The accuracy of molecular bond lengths computed by multireference electronic structure methods

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, Ron [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)], E-mail: shepard@tcg.anl.gov; Kedziora, Gary S. [High Performance Technologies Inc., 2435 5th Street, WPAFB, OH 45433 (United States); Lischka, Hans [Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna (Austria); Shavitt, Isaiah [Department of Chemistry, University of Illinois, 600 S. Mathews Avenue, Urbana, IL 61801 (United States); Mueller, Thomas [Juelich Supercomputer Centre, Research Centre Juelich, D-52425 Juelich (Germany); Szalay, Peter G. [Laboratory for Theoretical Chemistry, Institute of Chemistry, Eoetvoes Lorand University, P.O. Box 32, H-1518 Budapest (Hungary); Kallay, Mihaly [Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, P.O. Box 91, H-1521 Budapest (Hungary); Seth, Michael [Department of Chemistry, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta, T2N 1N4 (Canada)

    2008-06-16

    We compare experimental R{sub e} values with computed R{sub e} values for 20 molecules using three multireference electronic structure methods, MCSCF, MR-SDCI, and MR-AQCC. Three correlation-consistent orbital basis sets are used, along with complete basis set extrapolations, for all of the molecules. These data complement those computed previously with single-reference methods. Several trends are observed. The SCF R{sub e} values tend to be shorter than the experimental values, and the MCSCF values tend to be longer than the experimental values. We attribute these trends to the ionic contamination of the SCF wave function and to the corresponding systematic distortion of the potential energy curve. For the individual bonds, the MR-SDCI R{sub e} values tend to be shorter than the MR-AQCC values, which in turn tend to be shorter than the MCSCF values. Compared to the previous single-reference results, the MCSCF values are roughly comparable to the MP4 and CCSD methods, which are more accurate than might be expected due to the fact that these MCSCF wave functions include no extra-valence electron correlation effects. This suggests that static valence correlation effects, such as near-degeneracies and the ability to dissociate correctly to neutral fragments, play an important role in determining the shape of the potential energy surface, even near equilibrium structures. The MR-SDCI and MR-AQCC methods predict R{sub e} values with an accuracy comparable to, or better than, the best single-reference methods (MP4, CCSD, and CCSD(T)), despite the fact that triple and higher excitations into the extra-valence orbital space are included in the single-reference methods but are absent in the multireference wave functions. The computed R{sub e} values using the multireference methods tend to be smooth and monotonic with basis set improvement. The molecular structures are optimized using analytic energy gradients, and the timings for these calculations show the practical

  4. 共价键长的变化规律及计算%Variation Rule of Covalent Bond Length and Its Calculation Method

    Institute of Scientific and Technical Information of China (English)

    徐永群; 陈年友

    2001-01-01

    研究了共价键长的变化规律,提出了两个影响键长的参数,即配位体的半径与中心原子半径之比Rratio和由中心原子组成的基团的拓扑指数F2,用BP神经网络法逼近了50个、预测了11个简单无机分子中非含氢原子键的键长,其计算误差基本上在2pm以内。%The variation rule of covalent bond lengths is investigated.Two parameters which influence covalent bond lengths are presented: the radius ratio of the ligand to the centre atom and the topological index of the group of centre atom.With BP neural networks, 50 bond lengths have been approached and other 11 bond lengths have been forecasted. Errors of calculated bond lengths is almost within 2pm.

  5. Raman spectroscopic determination of the length, strength, compressibility, Debye temperature, elasticity, and force constant of the C-C bond in graphene.

    Science.gov (United States)

    Yang, X X; Li, J W; Zhou, Z F; Wang, Y; Yang, L W; Zheng, W T; Sun, Chang Q

    2012-01-21

    From the perspective of bond relaxation and bond vibration, we have formulated the Raman phonon relaxation of graphene, under the stimuli of the number-of-layers, the uni-axial strain, the pressure, and the temperature, in terms of the response of the length and strength of the representative bond of the entire specimen to the applied stimuli. Theoretical unification of the measurements clarifies that: (i) the opposite trends of the Raman shifts, which are due to the number-of-layers reduction, of the G-peak shift and arises from the vibration of a pair of atoms, while the D- and the 2D-peak shifts involve the z-neighbor of a specific atom; (ii) the tensile strain-induced phonon softening and phonon-band splitting arise from the asymmetric response of the C(3v) bond geometry to the C(2v) uni-axial bond elongation; (iii) the thermal softening of the phonons originates from bond expansion and weakening; and (iv) the pressure stiffening of the phonons results from bond compression and work hardening. Reproduction of the measurements has led to quantitative information about the referential frequencies from which the Raman frequencies shift as well as the length, energy, force constant, Debye temperature, compressibility and elastic modulus of the C-C bond in graphene, which is of instrumental importance in the understanding of the unusual behavior of graphene.

  6. X-ray-absorption fine structure determination of pressure-induced bond-angle changes in ReO3

    International Nuclear Information System (INIS)

    Houser, B.; Ingalls, R.

    2000-01-01

    We report here on a Marquardt-type method to fit the x-ray absorption fine structure (XAFS) of ReO 3 . We find that, when the ambient-pressure structure of ReO 3 is used as a starting point, the pressure dependence of the angle of the Re-O-Re bond in ReO 3 is fairly straightforwardly and robustly determined using FEFF curved-wave, multiple-scattering programs and is accurate to about ±1.5 degree sign or better. We present an argument that XAFS and scattering experiments fundamentally differ in what they measure in the case of nearly linear atomic bridges. Focussed multiple-scattering paths involving the Re-O-Re bridge make a contribution to the XAFS spectrum that is sensitive to the rms deviation of oxygen from the [100]-type directions. Fits to simulated spectra back up our contention that for XAFS experiments the effective position of the oxygen atom is its rms displacement whether the average displacement is zero or not. (c) 2000 The American Physical Society

  7. Investigation of field corrosion performance and bond/development length of galvanized reinforcing steel : [tech transfer summary].

    Science.gov (United States)

    2014-12-01

    In reinforced concrete systems, ensuring that a good bond between the : concrete and the embedded reinforcing steel is critical to long-term structural : performance. Without good bond between the two, the system simply cannot : behave as intended. :...

  8. Acute effects of anterior thigh foam rolling on hip angle, knee angle, and rectus femoris length in the modified Thomas test

    Directory of Open Access Journals (Sweden)

    Andrew D. Vigotsky

    2015-09-01

    Full Text Available Background. Foam rolling has been shown to acutely increase range of motion (ROM during knee flexion and hip flexion with the experimenter applying an external force, yet no study to date has measured hip extensibility as a result of foam rolling with controlled knee flexion and hip extension moments. The purpose of this study was to investigate the acute effects of foam rolling on hip extension, knee flexion, and rectus femoris length during the modified Thomas test.Methods. Twenty-three healthy participants (male = 7; female = 16; age = 22 ± 3.3 years; height = 170 ± 9.18 cm; mass = 67.7 ± 14.9 kg performed two, one-minute bouts of foam rolling applied to the anterior thigh. Hip extension and knee flexion were measured via motion capture before and after the foam rolling intervention, from which rectus femoris length was calculated.Results. Although the increase in hip extension (change = +1.86° (+0.11, +3.61; z(22 = 2.08; p = 0.0372; Pearson’s r = 0.43 (0.02, 0.72 was not due to chance alone, it cannot be said that the observed changes in knee flexion (change = −1.39° (−5.53, +2.75; t(22 = −0.70; p = 0.4933; Cohen’s d = − 0.15 (−0.58, 0.29 or rectus femoris length (change = −0.005 (−0.013, +0.003; t(22 = −1.30; p = 0.2070; Cohen’s d = − 0.27 (−0.70, 0.16 were not due to chance alone.Conclusions. Although a small change in hip extension was observed, no changes in knee flexion or rectus femoris length were observed. From these data, it appears unlikely that foam rolling applied to the anterior thigh will improve passive hip extension and knee flexion ROM, especially if performed in combination with a dynamic stretching protocol.

  9. Inhibition of nuclear T3 binding by fatty acids: dependence on chain length, unsaturated bonds, cis-trans configuration and esterification

    NARCIS (Netherlands)

    Wiersinga, W. M.; Platvoet-ter Schiphorst, M.

    1990-01-01

    1. Fatty acids have the capacity for inhibition of nuclear T3 binding (INB). The present studies were undertaken to describe the INB-activity of fatty acids as a function of chain length, unsaturated bonds, cis-trans configuration, and esterification. 2. Isolated rat liver nuclei were incubated with

  10. Application of Berlin's theorem to bond-length changes in isolated molecules and red- and blue-shifting H-bonded clusters

    Czech Academy of Sciences Publication Activity Database

    Wang, Weizhou; Hobza, Pavel

    2008-01-01

    Roč. 73, 6/7 (2008), s. 862-872 ISSN 0010-0765 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550510 Institutional research plan: CEZ:AV0Z40550506 Keywords : Berlin's theorem * H-bonding * Blue -shifting H-bonding Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.784, year: 2008

  11. The accuracy of three-dimensional fused deposition modeling (FDM) compared with three-dimensional CT-Scans on the measurement of the mandibular ramus vertical length, gonion-menton length, and gonial angle

    Science.gov (United States)

    Savitri, I. T.; Badri, C.; Sulistyani, L. D.

    2017-08-01

    Presurgical treatment planning plays an important role in the reconstruction and correction of defects in the craniomaxillofacial region. The advance of solid freeform fabrication techniques has significantly improved the process of preparing a biomodel using computer-aided design and data from medical imaging. Many factors are implicated in the accuracy of the 3D model. To determine the accuracy of three-dimensional fused deposition modeling (FDM) models compared with three-dimensional CT scans in the measurement of the mandibular ramus vertical length, gonion-menton length, and gonial angle. Eight 3D models were produced from the CT scan data (DICOM file) of eight patients at the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, University of Indonesia, Cipto Mangunkusumo Hospital. Three measurements were done three times by two examiners. The measurements of the 3D CT scans were made using OsiriX software, while the measurements of the 3D models were made using a digital caliper and goniometry. The measurement results were then compared. There is no significant difference between the measurements of the mandibular ramus vertical length, gonion-menton length, and gonial angle using 3D CT scans and FDM 3D models. FDM 3D models are considered accurate and are acceptable for clinical applications in dental and craniomaxillofacial surgery.

  12. 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.

  13. Evaluating the effect of dentin surface pretreatment on the static contact angle of a drop of a bonding agent: an in vitro study

    Directory of Open Access Journals (Sweden)

    Mehrdad Barekatain

    2016-03-01

    Full Text Available Introduction: The aim of this study was to investigate the effect of dentinal pretreatment on the static contact angle of a bonding agent as a measure of dentin surface wettability. Materials &Methods: Twenty mid-coronal dentin surfaces were prepared and randomly allocated to four groups (n=5 according to the priming solutions. All segments were etched with 35% phosphoric acid gel for 15 s, rinsed for 30 s and dried. Each group was rehydrated with 10 µL of distilled water, 0.2 % chlorhexidine, 70% ethanol and 5.25% Sodium Hypochlorite respectively and the excess solution was removed after 60 sec using an absorbent paper. Using a micro syringe, a droplet of the Adper Single Bond 2 was placed on each prepared surface. Then the profile and the static contact angle of the droplet were analyzed with a video-based optical contact angle measuring system. The statistical analysis was performed using One-way ANOVA and Dunnett’s t tests (p<0.05. Results: There was a statistically significant difference between the water and sodium hypochlorite groups which indicates the negative effect sodium hypochlorite may have on dentinal surface energy. (p=0.013. The differences between the water and ethanol groups (p=0.168 and between the water and chlorhexidine groups (p=0.665 were not significant. Conclusion: The use of 5.25% sodium hypochlorite as a priming solution in bonding procedure is not recommended. There is no improvement in dentinal surface wettability by using 70% ethanol or 0.2% chlorhexidine instead of water and the recommendation for use of any of the two should be based on other long-term or short-term effects they may have on the bonding procedure.

  14. The Hydrogen Bonded Structures of Two 5-Bromobarbituric Acids and Analysis of Unequal C5–X and C5–X′ Bond Lengths (X = X′ = F, Cl, Br or Me in 5,5-Disubstituted Barbituric Acids

    Directory of Open Access Journals (Sweden)

    Thomas Gelbrich

    2016-04-01

    Full Text Available The crystal structure of the methanol hemisolvate of 5,5-dibromobarbituric acid (1MH displays an H-bonded layer structure which is based on N–H∙∙∙O=C, N–H∙∙∙O(MeOH and (MeOHO–H∙∙∙O interactions. The barbiturate molecules form an H-bonded substructure which has the fes topology. 5,5′-Methanediylbis(5-bromobarbituric acid 2, obtained from a solution of 5,5-dibromobarbituric acid in nitromethane, displays a N–H···O=C bonded framework of the sxd type. The conformation of the pyridmidine ring and the lengths of the ring substituent bonds C5–X and C5–X′ in crystal forms of 5,5-dibromobarbituric acid and three closely related analogues (X = X′ = Br, Cl, F, Me have been investigated. In each case, a conformation close to a C5-endo envelope is correlated with a significant lengthening of the axial C5–X′ in comparison to the equatorial C5–X bond. Isolated molecule geometry optimizations at different levels of theory confirm that the C5-endo envelope is the global conformational energy minimum of 5,5-dihalogenbarbituric acids. The relative lengthening of the axial bond is therefore interpreted as an inherent feature of the preferred envelope conformation of the pyrimidine ring, which minimizes repulsive interactions between the axial substituent and pyrimidine ring atoms.

  15. Bond length and electric current oscillation of long linear carbon chains: Density functional theory, MpB model, and quantum spin transport studies

    International Nuclear Information System (INIS)

    Oeiras, R. Y.; Silva, E. Z. da

    2014-01-01

    Carbon linear atomic chains attached to graphene have experimentally been produced. Motivated by these results, we study the nature of the carbon bonds in these nanowires and how it affects their electrical properties. In the present study we investigate chains with different numbers of atoms and we observe that nanowires with odd number of atoms present a distinct behavior than the ones with even numbers. Using graphene nanoribbons as leads, we identify differences in the quantum transport of the chains with the consequence that even and odd numbered chains have low and high electrical conduction, respectively. We also noted a dependence of current with the wire size. We study this unexpected behavior using a combination of first principles calculations and simple models based on chemical bond theory. From our studies, the electrons of carbon nanowires present a quasi-free electron behavior and this explains qualitatively the high electrical conduction and the bond lengths with unexpected values for the case of odd nanowires. Our study also allows the understanding of the electric conduction dependence with the number of atoms and their parity in the chain. In the case of odd number chains a proposed π-bond (MpB) model describes unsaturated carbons that introduce a mobile π-bond that changes dramatically the structure and transport properties of these wires. Our results indicate that the nature of bonds plays the main role in the oscillation of quantum electrical conduction for chains with even and odd number of atoms and also that nanowires bonded to graphene nanoribbons behave as a quasi-free electron system, suggesting that this behavior is general and it could also remain if the chains are bonded to other materials

  16. A method of coupling the Paternò-Büchi reaction with direct infusion ESI-MS/MS for locating the C[double bond, length as m-dash]C bond in glycerophospholipids.

    Science.gov (United States)

    Stinson, Craig A; Xia, Yu

    2016-06-21

    Tandem mass spectrometry (MS/MS) coupled with soft ionization is established as an essential platform for lipid analysis; however, determining high order structural information, such as the carbon-carbon double bond (C[double bond, length as m-dash]C) location, remains challenging. Recently, our group demonstrated a method for sensitive and confident lipid C[double bond, length as m-dash]C location determination by coupling online the Paternò-Büchi (PB) reaction with nanoelectrospray ionization (nanoESI) and MS/MS. Herein, we aimed to expand the scope of the PB reaction for lipid analysis by enabling the reaction with infusion ESI-MS/MS at much higher flow rates than demonstrated in the nanoESI setup (∼20 nL min(-1)). In the new design, the PB reaction was effected in a fused silica capillary solution transfer line, which also served as a microflow UV reactor, prior to ESI. This setup allowed PB reaction optimization and kinetics studies. Under optimized conditions, a maximum of 50% PB reaction yield could be achieved for a standard glycerophosphocholine (PC) within 6 s of UV exposure over a wide flow rate range (0.1-10 μL min(-1)). A solvent composition of 7 : 3 acetone : H2O (with 1% acid or base modifier) allowed the highest PB yields and good lipid ionization, while lower yields were obtained with an addition of a variety of organic solvents. Radical induced lipid peroxidation was identified to induce undesirable side reactions, which could be effectively suppressed by eliminating trace oxygen in the solution via N2 purge. Finally, the utility of coupling the PB reaction with infusion ESI-MS/MS was demonstrated by analyzing a yeast polar lipid extract where C[double bond, length as m-dash]C bond locations were revealed for 35 glycerophospholipids (GPs).

  17. Aggregation of bovine serum albumin upon cleavage of its disulfide bonds, studied by the time-resolved small-angle X-ray scattering technique with synchrotron radiation

    International Nuclear Information System (INIS)

    Ueki, Tatzuo; Inoko, Yoji; Izumi, Yoshinobu; Tagawa, Hiroyuki; Muroga, Yoshio

    1985-01-01

    A rapid mixing system of the stopped-flow type, used with small-angle X-ray scattering equipment using synchrotron radiation, is described. The process of aggregation of bovine serum albumin was traced with a time interval of 50 s, initiated upon cleavage of its disulfide bonds by reduction with dithiothreitol. The results indicate that a 218-fold molar excess of dithiothreitol over the number of moles of disulfide bonds in bovine serum albumin is sufficient to initiate the reaction immediately after mixing, which reaches equilibrium in about 15 min. On the other hand, half this amount is not sufficient to initiate the reaction, so that the reaction is delayed by about 150 s. Such a single-shot time-resolved experiment showed that experiments with a time interval of 100 ms are possible with repeated multi-shot runs. (Auth.)

  18. Aggregation of bovine serum albumin upon cleavage of its disulfide bonds, studied by the time-resolved small-angle X-ray scattering technique with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ueki, Tatzuo; Inoko, Yoji; Hiragi, Yuzuru; Kataoka, Mikio; Amemiya, Yoshiyuki; Izumi, Yoshinobu; Tagawa, Hiroyuki; Muroga, Yoshio

    1985-11-01

    A rapid mixing system of the stopped-flow type, used with small-angle X-ray scattering equipment using synchrotron radiation, is described. The process of aggregation of bovine serum albumin was traced with a time interval of 50s, initiated upon cleavage of its disulfide bonds by reduction with dithiothreitol. The results indicate that a 218-fold molar excess of dithiothreitol over the number of moles of disulfide bonds in bovine serum albumin is sufficient to initiate the reaction immediately after mixing, which reaches equilibrium in about 15 min. On the other hand, half this amount is not sufficient to initiate the reaction, so that the reaction is delayed by about 150s. Such a single-shot time-resolved experiment showed that experiments with a time interval of 100 ms are possible with repeated multi-shot runs. 26 refs.; 8 figs.

  19. Association of Bruch's membrane opening and optic disc morphology to axial length and visual field defects in eyes with primary open-angle glaucoma.

    Science.gov (United States)

    Nakanishi, Hideo; Suda, Kenji; Yoshikawa, Munemitsu; Akagi, Tadamichi; Kameda, Takanori; Ikeda, Hanako Ohashi; Yokota, Satoshi; Kurimoto, Yasuo; Tsujikawa, Akitaka

    2018-03-01

    To examine the morphology of Bruch's membrane opening (BMO), optic disc, and peripapillary atrophy (PPA) by scanning laser ophthalmoscopy (SLO) and spectral-domain optical coherence tomography (SD-OCT), and to determine their association with the axial length and visual field defects. This was a cross-sectional study of 94 eyes of 56 subjects; 77 eyes were diagnosed with primary open-angle glaucoma and 17 eyes as normal. The margins of the optic disc were determined in the SLO images, and that of the BMO in the SD-OCT images. The ovality and area of the BMO and the optic disc were measured. The beta and gamma-PPA areas were also measured. The association of each parameter with the axial length and the mean deviation (MD) of the visual field tests was determined by generalized estimating equations (GEEs). The optic disc ovality was associated with the axial length and the MD (β = -0.47, P = 7.6 × 10 -4 and β = 0.12, P = 0.040). The BMO ovality was not significantly associated with the axial length and the MD. The BMO area was associated with the axial length (β = 0.30, P = 0.029). A larger BMO area was associated with a thinner BMO-based neuroretinal rim width (BMO-MRW) after adjustments for the MD (β = -0.30, P = 2.1 × 10 -4 ). The beta- and gamma-PPA areas were associated with the axial length (β = 0.50, P = 7.4 × 10 -5 and β = 0.62, P = 4.2 × 10 -6 ). The optic disc ovality was associated with both the axial length and MD, whereas BMO ovality was not. Attention should be paid to the influence of the axial length-related enlargement of the BMO.

  20. Photoelectron spectroscopy of liquid water and aqueous solution: Electron effective attenuation lengths and emission-angle anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Ottosson, Niklas [Department of Physics, Uppsala University, SE-75121 Uppsala (Sweden); Faubel, Manfred [Max-Planck-Institut fuer Dynamik und Selbstorganisation, Bunsenstrasse 10, D-37073 Goettingen (Germany); Bradforth, Stephen E. [Department of Chemistry, University of Southern California, Los Angeles, CA 90089 (United States); Jungwirth, Pavel [Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, and Center for Biomolecules and Complex Molecular Systems, Flemingovo nam. 2, 16610 Prague 6 (Czech Republic); Winter, Bernd, E-mail: winter@bessy.d [Helmholtz-Zentrum Berlin fuer Materialien und Energie, and BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Max-Born-Institut, Max-Born-Strasse 2A, D-12489 Berlin (Germany)

    2010-03-15

    Photoelectron (PE) spectroscopy measurements from liquid water and from a 4 m NaI aqueous solution are performed using a liquid microjet in combination with soft X-ray synchrotron radiation. From the oxygen 1s PE signal intensity from liquid water, measured as a function of photon energy (up to 1500 eV), we quantitatively determine relative electron inelastic effective attenuation lengths (EAL) for (photo)electron kinetic energies in the 70-900 eV range. In order to determine the absolute electron escape depths a calibration point is needed, which is not directly accessible by experiment. This information can instead be indirectly derived by comparing PE experiments and molecular dynamics (MD) simulations of an aqueous solution interface where density profiles of water, anions, and cations are distinctively different. We have chosen sodium iodide in water because iodide has a considerable propensity for the solution surface, whereas the sodium cation is repelled from the surface. By measuring the intensities of photoelectrons emitted from different orbitals of different symmetries from each aqueous ion we also evaluate whether gas-phase ionization cross sections and asymmetry parameters can describe the photoemission from ions at and near the aqueous solution/vapor interface. We show that gas-phase data reproduce surprisingly well the experimental observations for hydrated ions as long as the photon energy is sufficiently far above the ionization threshold. Electrons detected at the higher photon energies originate predominantly from deeper layers, suggesting that bulk-solution electron elastic scattering is relatively weak.

  1. Achieving ultrafine grained and homogeneous AA1050/ZnO nanocomposite with well-developed high angle grain boundaries through accumulative press bonding

    Energy Technology Data Exchange (ETDEWEB)

    Amirkhanlou, Sajjad, E-mail: s.amirkhanlou@aut.ac.ir [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Ketabchi, Mostafa; Parvin, Nader; Askarian, Masoomeh [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Carreño, Fernando [Department of Physical Metallurgy, CENIM-CSIC, Av. Gregorio del Amo 8, 28040 Madrid (Spain)

    2015-03-11

    Aluminum matrix nanocomposites with 2 vol% ZnO nanoparticles were produced using accumulative press bonding (APB) as a very effective and novel severe plastic deformation process. Microstructural evaluation and mechanical properties of specimens were characterized by field-emission scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), electron backscatter diffraction (EBSD) and tensile test. Microstructure of AA1050/ZnO nanocomposite showed a uniform distribution of ZnO nanoparticles throughout the aluminum matrix. STEM and EBSD observations revealed that ultrafine-grained Al/ZnO nanocomposite with the average grain size of <500 nm and well-developed high angle grain boundaries (80% high angle boundaries and 37° average misorientation angle) was successfully obtained by performing 14 cycles of the APB process. When the number of APB cycles increased the tensile strength of Al/ZnO nanocomposite improved and reached 228 MPa after 14 cycles, which was 2.6 and 1.3 times greater than the obtained values for annealed (raw material, 88 MPa) and monolithic aluminum (180 MPa), respectively.

  2. Comparison of the Calcaneal Pitch Angle and Modified Projection Area Per Length Squared Method for Medial Longitudinal Arch Evaluation of the Foot

    Directory of Open Access Journals (Sweden)

    Esat Kıter2

    2012-12-01

    Full Text Available Objective: To compare the calcaneal pitch angle (CPA values measured on direct lateral radiographs of feet, and the modified projection area per length squared (PAL, which was calculated as a new method for the evaluation of the medial longitudinal arch (MLA of the foot.Material and Methods: Direct lateral radiographs of patients who had weightbearing feet radiographies for any reason except trauma were retrospectively obtained from the archives. Direct lateral radiographs of the feet were printed and a transparent sheet was placed on it. A straight line was drawn between the most plantar process of the calcaneus and the head of the first metatarsal bone for the calculation of the PAL of the MLA. Two semilunar arcs were drawn upon this straight line. PAL1 and PAL2 were estimated using a point-counting technique. The CPA, lateral talo-calcaneal angles (LTCA, and talo-first metatarsal angles (TFMA were measured. The correlations between PAL1, PAL2 of right and left feet and CPA, LTCA, and TFMA were explored.Results: Fifty patients (27 females, 23 males with a mean age of 40.12 (4-78 years were evaluated. Significant correlations were detected between PAL1, PAL2 and CPA, and TFMA for both right and left feet (p<0.05. Conclusion: A significant correlation was detected between the modified PAL method as a new technique and the standard CPA method for MLA evaluation. The PAL method is suggested as a simple and practical method for MLA evaluation.

  3. Combining Single-Molecule Optical Trapping and Small-Angle X-Ray Scattering Measurements to Compute the Persistence Length of a Protein ER/K alpha-Helix

    DEFF Research Database (Denmark)

    Sivaramakrishnan, S.; Sung, J.; Ali, M.

    2009-01-01

    as a force transducer, rigid spacer, or flexible linker in proteins. In this study, we quantity this flexibility in terms of persistence length, namely the length scale over which it is rigid. We use single-molecule optical trapping and small-angle x-ray scattering, combined with Monte Carlo simulations...

  4. Variation of solvent scattering-length density small-angle neutron scattering as a means of determining structure of composite materials

    International Nuclear Information System (INIS)

    Hjelm, R.P.; Wampler, W.; Gerspacher, M.

    1994-01-01

    As part of our work on the, structure of composite materials we have been exploring the use of small-angle neutron scattering using the method of contrast variation to dissect the component form, structure and distribution. This approach has resulted in a new look at very old problem reinforcement of elastomers by carbon black. Using this approach we studied an experimental high surface area (HSA) carbon black and a gel of ''HSA-bound'' rubber in cyclohexane/deuterocyclohexane mixtures. HSA in cyclohexane is found to be short rodlike particle aggregates. The aggregates have a shell-core structure with a high density graphitic outer shell and an inner core of lower density amorphous carbon. The core is continuous throughout the carbon black aggregate, making the aggregate a stiff, integral unit. Contrast variation of swollen composite gels shows that there are two length scales in the gel structure. Above 10 Angstrom, scattering from carbon black predominates, and below 10 Angstrom the scattering is from both carbon black and the elastomer. The HSA in the composite is completely embedded in polyisoprene. An estimate of the carbon black structure factor shows strong exclusion of neighboring aggregates, probably from excluded volume effects. The surface structure of the carbon black is unaltered by the interactions with elastomer and appears smooth over length scales above about 10 Angstrom. These results show that contrast variation can provide information on composite structure that is not available by other means. This information relates to the reinforcement mechanism of elastomers by carbon blacks

  5. Utilisation of an eta(3)-allyl hydride complex, formed by UV irradiation, as a controlled source of 16-electron (eta(5)-C(5)Me(5))Rh(CH(2)[double bond, length as m-dash]CHMe).

    Science.gov (United States)

    Sexton, Catherine J; López-Serrano, Joaquín; Lledós, Agustí; Duckett, Simon B

    2008-10-21

    Low temperature UV irradiation of solutions of (eta(5)-C(5)Me(5))Rh(CH(2)[double bond, length as m-dash]CHMe)(2) yields (eta(5)-C(5)Me(5))Rh(eta(3)-CH(2)CHCH(2))(H), which provides controlled access to the 16-electron fragment (eta(5)-C(5)Me(5))Rh(CH(2)[double bond, length as m-dash]CHMe).

  6. Safe-by-Design CuO Nanoparticles via Fe-Doping, Cu-O Bond Length Variation, and Biological Assessment in Cells and Zebrafish Embryos.

    Science.gov (United States)

    Naatz, Hendrik; Lin, Sijie; Li, Ruibin; Jiang, Wen; Ji, Zhaoxia; Chang, Chong Hyun; Köser, Jan; Thöming, Jorg; Xia, Tian; Nel, Andre E; Mädler, Lutz; Pokhrel, Suman

    2017-01-24

    The safe implementation of nanotechnology requires nanomaterial hazard assessment in accordance with the material physicochemical properties that trigger the injury response at the nano/bio interface. Since CuO nanoparticles (NPs) are widely used industrially and their dissolution properties play a major role in hazard potential, we hypothesized that tighter bonding of Cu to Fe by particle doping could constitute a safer-by-design approach through decreased dissolution. Accordingly, we designed a combinatorial library in which CuO was doped with 1-10% Fe in a flame spray pyrolysis reactor. The morphology and structural properties were determined by XRD, BET, Raman spectroscopy, HRTEM, EFTEM, and EELS, which demonstrated a significant reduction in the apical Cu-O bond length while simultaneously increasing the planar bond length (Jahn-Teller distortion). Hazard screening was performed in tissue culture cell lines and zebrafish embryos to discern the change in the hazardous effects of doped vs nondoped particles. This demonstrated that with increased levels of doping there was a progressive decrease in cytotoxicity in BEAS-2B and THP-1 cells, as well as an incremental decrease in the rate of hatching interference in zebrafish embryos. The dissolution profiles were determined and the surface reactions taking place in Holtfreter's solution were validated using cyclic voltammetry measurements to demonstrate that the Cu + /Cu 2+ and Fe 2+ /Fe 3+ redox species play a major role in the dissolution process of pure and Fe-doped CuO. Altogether, a safe-by-design strategy was implemented for the toxic CuO particles via Fe doping and has been demonstrated for their safe use in the environment.

  7. In situ ultra-small-angle X-ray scattering study under uniaxial stretching of colloidal crystals prepared by silica nanoparticles bearing hydrogen-bonding polymer grafts

    Directory of Open Access Journals (Sweden)

    Ryohei Ishige

    2016-05-01

    Full Text Available A molded film of single-component polymer-grafted nanoparticles (SPNP, consisting of a spherical silica core and densely grafted polymer chains bearing hydrogen-bonding side groups capable of physical crosslinking, was investigated by in situ ultra-small-angle X-ray scattering (USAXS measurement during a uniaxial stretching process. Static USAXS revealed that the molded SPNP formed a highly oriented twinned face-centered cubic (f.c.c. lattice structure with the [11−1] plane aligned nearly parallel to the film surface in the initial state. Structural analysis of in situ USAXS using a model of uniaxial deformation induced by rearrangement of the nanoparticles revealed that the f.c.c. lattice was distorted in the stretching direction in proportion to the macroscopic strain until the strain reached 35%, and subsequently changed into other f.c.c. lattices with different orientations. The lattice distortion and structural transition behavior corresponded well to the elastic and plastic deformation regimes, respectively, observed in the stress–strain curve. The attractive interaction of the hydrogen bond is considered to form only at the top surface of the shell and then plays an effective role in cross-linking between nanoparticles. The rearrangement mechanism of the nanoparticles is well accounted for by a strong repulsive interaction between the densely grafted polymer shells of neighboring particles.

  8. Analyses of Non-bonding Length, Partial Atomics Charge and Electrostatic Energy from Molecular Dynamics Simulation of Phospholipase A2 – Substrate

    Directory of Open Access Journals (Sweden)

    Nirwan Syarif

    2016-11-01

    Full Text Available This paper reports molecular dynamics simulation of phospholipase A2 (PLA2– substrate that has been done. Non-bonding length, partial atomic charge and electrostatic energy were used to evaluation the interaction between PLA2 and substrate. The research was subjected for three types of PLA2 of different sources, i.e, homo sapien, bovinus and porcinus, by using computer files of their molecular structures. The files with code 3elo, 1bp2, dan 1y6o were downloaded from protein data bank. Substrate structure can be found in 1y60 and was separated from its enzyme structure and docked into two other PLA2 structures for simulation purpose. Molecular dynamics simulations were done for 30000 steps with constant in number of molecules, volume and temperature (NVT. The results showed the existing of flip-flop mechanism as basic feature of PLA2 – substrate reactions. Interaction length analysis results indicated the presence of water molecules on the structures of 1bp2 and 3elo at the time of the simulation was completed. The existence of aspagine at the reaction site confirmed the theory that this amino acid is responsible for the survival of the reaction. the electrostatic energy increased substantially in the interaction after homo sapien PLA2 (3elo and Bovinus (1bp2 with the substrate. Inverse effect took place in the PLA porcinus (1y6o.

  9. Deuteriation of an asymmetric short hydrogen bond. X-ray crystal structure of KF.(CH2CO2D)2

    International Nuclear Information System (INIS)

    Emsley, J.; Jones, D.J.; Kuroda, R.

    1981-01-01

    Deuteriation of the strong hydrogen bonds of KF.(CH 2 CO 2 H) 2 shows no isotope effect on the bond lengths. The only significant change is in the bond angle at the fluoride ion which widens to 128.5 from 116 0 . The i.r. spectrum shows very little change. Since the O-H ... F - hydrogen bonds are highly asymmetric, these observations challenge previous predictions about the effects of deuteriation on such bonds. (author)

  10. Chemical Speciation and Bond Lengths of Organic Solutes by Core-Level Spectroscopy: pH and Solvent Influence on p-Aminobenzoic Acid.

    Science.gov (United States)

    Stevens, Joanna S; Gainar, Adrian; Suljoti, Edlira; Xiao, Jie; Golnak, Ronny; Aziz, Emad F; Schroeder, Sven L M

    2015-05-04

    Through X-ray absorption and emission spectroscopies, the chemical, electronic and structural properties of organic species in solution can be observed. Near-edge X-ray absorption fine structure (NEXAFS) and resonant inelastic X-ray scattering (RIXS) measurements at the nitrogen K-edge of para-aminobenzoic acid reveal both pH- and solvent-dependent variations in the ionisation potential (IP), 1s→π* resonances and HOMO-LUMO gap. These changes unequivocally identify the chemical species (neutral, cationic or anionic) present in solution. It is shown how this incisive chemical state sensitivity is further enhanced by the possibility of quantitative bond length determination, based on the analysis of chemical shifts in IPs and σ* shape resonances in the NEXAFS spectra. This provides experimental access to detecting even minor variations in the molecular structure of solutes in solution, thereby providing an avenue to examining computational predictions of solute properties and solute-solvent interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Enhanced photocatalytic degradation of Amaranth dye on mesoporous anatase TiO2: evidence of C-N, N[double bond, length as m-dash]N bond cleavage and identification of new intermediates.

    Science.gov (United States)

    Naik, Amarja P; Salkar, Akshay V; Majik, Mahesh S; Morajkar, Pranay P

    2017-07-01

    The photocatalytic degradation mechanism of Amaranth, a recalcitrant carcinogenic azo dye, was investigated using mesoporous anatase TiO 2 under sunlight. Mesoporous anatase TiO 2 of a high photocatalytic activity has been synthesized using a sol-gel method and its photocatalytic activity for the degradation of Amaranth dye has been evaluated with respect to Degussa P25. The effect of bi-dentate complexing agents like oxalic acid, ethylene glycol and urea on the surface properties of TiO 2 catalyst has been investigated using TG-DTA, FTIR, HR-TEM, SAED, PXRD, EDS, UV-DRS, PL, BET N 2 adsorption-desorption isotherm studies and BJH analysis. The influence of catalyst properties such as the mesoporous network, pore volume and surface area on the kinetics of degradation of Amaranth as a function of irradiation time under natural sunlight has been monitored using UV-Vis spectroscopy. The highest rate constant value of 0.069 min -1 was obtained for the photocatalytic degradation of Amaranth using TiO 2 synthesized via a urea assisted sol-gel synthesis method. The effect of the reaction conditions such as pH, TiO 2 concentration and Amaranth concentration on the photodegradation rate has been investigated. The enhanced photocatalytic activity of synthesized TiO 2 in comparison with P25 is attributed to the mesoporous nature of the catalyst leading to increased pore diameter, pore volume, surface area and enhanced charge carrier separation efficiency. New intermediates of photocatalytic degradation of Amaranth, namely, sodium-3-hydroxynaphthalene-2,7-disulphonate, 3-hydroxynaphthalene, sodium-4-aminonaphthalenesulphonate and sodium-4-aminobenzenesulphonate have been identified using LC-ESI-MS for the very first time, providing direct evidence for simultaneous bond cleavage pathways (-C-N-) and (-N[double bond, length as m-dash]N-). A new plausible mechanism of TiO 2 catalysed photodegradation of Amaranth along with the comparison of its toxicity to that of its degradation

  12. Crystallochemistry of rhenium compounds with metal-metal bonds

    International Nuclear Information System (INIS)

    Koz'min, P.A.; Surazhskaya, M.D.

    1980-01-01

    A review is presented including a brief description of atomic structure of 59 coordination rhenium compounds with metal-metal bond. The most important bond lengths and valent angles are presented for each compound. The dependence of rhenium-rhenium bond length on its multiplicity is discussed and possible causes of deviations from this dependence (namely, axial ligand presence, steric repulsion of ligands) are considered. On the basis of qualitative comparison of electronegativity of ligands in dimer compounds with quarternary bond of rhenium-rhenium a supposition is made on the influence of formal charge of atomic group and summary electro-negativity of ligands on the possibility of the metal-metal bond formation

  13. X-ray diffraction and chemical bonding

    International Nuclear Information System (INIS)

    Bats, J.W.

    1976-01-01

    Chemical bonds are investigated in sulfamic acid (H 3 N-SO 3 ), sodium sulfonlate dihydrate (H 2 NC 6 H 4 SO 3 Na.2H 2 O), 2,5-dimercaptothiadiazole (HS-C 2 N 2 S-SH), sodium cyanide dihydrate (NaCN.2H 2 O), sodium thiocyanate (NaSCN) and ammonium thiocyanate (NH 4 SCN) by X-ray diffraction, and if necessary completed with neutron diffraction. Crystal structures and electron densities are determined together with bond length and angles. Also the effects of thermal motion are discussed

  14. Phase Behavior of Blends of Linear and Branched Polyethylenes on Micron-Length Scales via Ultra-Small-Angle Neutron Scattering (USANS)

    International Nuclear Information System (INIS)

    Agamalian, M.M.; Alamo, R.G.; Londono, J.D.; Mandelkern, L.; Wignall, G.D.

    1999-01-01

    SANS experiments on blends of linear, high density (HD) and long chain branched, low density (LD) polyethylenes indicate that these systems form a one-phase mixture in the melt. However, the maximum spatial resolution of pinhole cameras is approximately equal to 10 3 and it has therefore been suggested that data might also be interpreted as arising from a bi-phasic melt with large a particle size ( 1 m), because most of the scattering from the different phases would not be resolved. We have addressed this hypothesis by means of USANS experiments, which confirm that HDPEILDPE blends are homogenous in the melt on length scales up to 20 m. We have also studied blends of HDPE and short-chain branched linear low density polyethylenes (LLDPEs), which phase separate when the branch content is sufficiently high. LLDPEs prepared with Ziegler-Natta catalysts exhibit a wide distribution of compositions, and may therefore be thought of as a blend of different species. When the composition distribution is broad enough, a fraction of highly branched chains may phase separate on m-length scales, and USANS has also been used to quantify this phenomenon

  15. Comparative analysis of the anterior and posterior length and deflection angle of the cranial base, in individuals with facial Pattern I, II and III

    Directory of Open Access Journals (Sweden)

    Guilherme Thiesen

    2013-02-01

    Full Text Available OBJECTIVE: This study evaluated the variations in the anterior cranial base (S-N, posterior cranial base (S-Ba and deflection of the cranial base (SNBa among three different facial patterns (Pattern I, II and III. METHOD: A sample of 60 lateral cephalometric radiographs of Brazilian Caucasian patients, both genders, between 8 and 17 years of age was selected. The sample was divided into 3 groups (Pattern I, II and III of 20 individuals each. The inclusion criteria for each group were the ANB angle, Wits appraisal and the facial profile angle (G'.Sn.Pg'. To compare the mean values obtained from (SNBa, S-N, S-Ba each group measures, the ANOVA test and Scheffé's Post-Hoc test were applied. RESULTS AND CONCLUSIONS: There was no statistically significant difference for the deflection angle of the cranial base among the different facial patterns (Patterns I, II and III. There was no significant difference for the measures of the anterior and posterior cranial base between the facial Patterns I and II. The mean values for S-Ba were lower in facial Pattern III with statistically significant difference. The mean values of S-N in the facial Pattern III were also reduced, but without showing statistically significant difference. This trend of lower values in the cranial base measurements would explain the maxillary deficiency and/or mandibular prognathism features that characterize the facial Pattern III.OBJETIVO: o presente estudo avaliou as variações da base craniana anterior (S-N, base craniana posterior (S-Ba, e ângulo de deflexão da base do crânio (SNBa entre três diferentes padrões faciais (Padrão I, II e III. MÉTODOS: selecionou-se uma amostra de 60 telerradiografias em norma lateral de pacientes brasileiros leucodermas, de ambos os sexos, com idades entre 8 anos e 17 anos. A amostra foi dividida em três grupos (Padrão I, II e III, sendo cada grupo constituído de 20 indivíduos. Os critérios de seleção dos indivíduos para cada grupo

  16. Low-Resolution Structure of the Full-Length Barley (Hordeum vulgare) SGT1 Protein in Solution, Obtained Using Small-Angle X-Ray Scattering

    Science.gov (United States)

    Taube, Michał; Pieńkowska, Joanna R.; Jarmołowski, Artur; Kozak, Maciej

    2014-01-01

    SGT1 is an evolutionarily conserved eukaryotic protein involved in many important cellular processes. In plants, SGT1 is involved in resistance to disease. In a low ionic strength environment, the SGT1 protein tends to form dimers. The protein consists of three structurally independent domains (the tetratricopeptide repeats domain (TPR), the CHORD- and SGT1-containing domain (CS), and the SGT1-specific domain (SGS)), and two less conserved variable regions (VR1 and VR2). In the present study, we provide the low-resolution structure of the barley (Hordeum vulgare) SGT1 protein in solution and its dimer/monomer equilibrium using small-angle scattering of synchrotron radiation, ab-initio modeling and circular dichroism spectroscopy. The multivariate curve resolution least-square method (MCR-ALS) was applied to separate the scattering data of the monomeric and dimeric species from a complex mixture. The models of the barley SGT1 dimer and monomer were formulated using rigid body modeling with ab-initio structure prediction. Both oligomeric forms of barley SGT1 have elongated shapes with unfolded inter-domain regions. Circular dichroism spectroscopy confirmed that the barley SGT1 protein had a modular architecture, with an α-helical TPR domain, a β-sheet sandwich CS domain, and a disordered SGS domain separated by VR1 and VR2 regions. Using molecular docking and ab-initio protein structure prediction, a model of dimerization of the TPR domains was proposed. PMID:24714665

  17. Peculiarities of structure of rare earth β-diketonates and carboxylates with mostly ionic type of bond

    International Nuclear Information System (INIS)

    Kuz'mina, N.P.; Martynenko, L.I.

    1996-01-01

    X-ray diffraction data on β-diketonates and carboxylates of rare earths (3) have been analyzed. Essential features of the compounds structure have been formulated. It is shown that in the compounds mentioned irregular distortions of chelate cycles over the length and angles of bonds are observed, there is no regularity in the ratios of metal-ligand bridge and chelate bond lengths both in the series of compounds of different composition and inside one compound. 2 refs

  18. Engineering a disulfide bond in the lid hinge region of Rhizopus chinensis lipase: increased thermostability and altered acyl chain length specificity.

    Directory of Open Access Journals (Sweden)

    Xiao-Wei Yu

    Full Text Available The key to enzyme function is the maintenance of an appropriate balance between molecular stability and structural flexibility. The lid domain which is very important for "interfacial activation" is the most flexible part in the lipase structure. In this work, rational design was applied to explore the relationship between lid rigidity and lipase activity by introducing a disulfide bond in the hinge region of the lid, in the hope of improving the thermostability of R. chinensis lipase through stabilization of the lid domain without interfering with its catalytic performance. A disulfide bridge between F95C and F214C was introduced into the lipase from R. chinensis in the hinge region of the lid according to the prediction of the "Disulfide by Design" algorithm. The disulfide variant showed substantially improved thermostability with an eleven-fold increase in the t(1/2 value at 60°C and a 7°C increase of T(m compared with the parent enzyme, probably contributed by the stabilization of the geometric structure of the lid region. The additional disulfide bond did not interfere with the catalytic rate (k(cat and the catalytic efficiency towards the short-chain fatty acid substrate, however, the catalytic efficiency of the disulfide variant towards pNPP decreased by 1.5-fold probably due to the block of the hydrophobic substrate channel by the disulfide bond. Furthermore, in the synthesis of fatty acid methyl esters, the maximum conversion rate by RCLCYS reached 95% which was 9% higher than that by RCL. This is the first report on improving the thermostability of the lipase from R. chinensis by introduction of a disulfide bond in the lid hinge region without compromising the catalytic rate.

  19. Absolute and relative-rate measurement of the rate coefficient for reaction of perfluoro ethyl vinyl ether (C2F5OCF[double bond, length as m-dash]CF2) with OH.

    Science.gov (United States)

    Srinivasulu, G; Bunkan, A J C; Amedro, D; Crowley, J N

    2018-01-31

    The rate coefficient (k 1 ) for the reaction of OH radicals with perfluoro ethyl vinyl ether (PEVE, C 2 F 5 OCF[double bond, length as m-dash]CF 2 ) has been measured as a function of temperature (T = 207-300 K) using the technique of pulsed laser photolysis with detection of OH by laser-induced fluorescence (PLP-LIF) at pressures of 50 or 100 Torr N 2 bath gas. In addition, the rate coefficient was measured at 298 K and in one atmosphere of air by the relative-rate technique with loss of PEVE and reference reactant monitored in situ by IR absorption spectroscopy. The rate coefficient has a negative temperature dependence which can be parameterized as: k 1 (T) = 6.0 × 10 -13  exp[(480 ± 38/T)] cm 3 molecule -1 s -1 and a room temperature value of k 1 (298 K) = (3.0 ± 0.3) × 10 -12 cm 3 molecule -1 s -1 . Highly accurate rate coefficients from the PLP-LIF experiments were achieved by optical on-line measurements of PEVE and by performing the measurements at two different apparatuses. The large rate coefficient and the temperature dependence indicate that the reaction proceeds via OH addition to the C[double bond, length as m-dash]C double bond, the high pressure limit already being reached at 50 Torr N 2 . Based on the rate coefficient and average OH levels, the atmospheric lifetime of PEVE was estimated to be a few days.

  20. Molecular dynamics simulation for the influence of incident angles of energetic carbon atoms on the structure and properties of diamond-like carbon films

    International Nuclear Information System (INIS)

    Li, Xiaowei; Ke, Peiling; Lee, Kwang-Ryeol; Wang, Aiying

    2014-01-01

    The influence of incident angles of energetic carbon atoms (0–60°) on the structure and properties of diamond-like carbon (DLC) films was investigated by the molecular dynamics simulation using a Tersoff interatomic potential. The present simulation revealed that as the incident angles increased from 0 to 60°, the surface roughness of DLC films increased and the more porous structure was generated. Along the growth direction of DLC films, the whole system could be divided into four regions including substrate region, transition region, stable region and surface region except the case at the incident angle of 60°. When the incident angle was 45°, the residual stress was significantly reduced by 12% with little deterioration of mechanical behavior. The further structure analysis using both the bond angles and bond length distributions indicated that the compressive stress reduction mainly resulted from the relaxation of highly distorted C–C bond length. - Highlights: • The dependence of films properties on different incident angles was investigated. • The change of incident angles reduced the stress without obvious damage of density. • The stress reduction attributed to the relaxation of highly distorted bond length

  1. Measurement of the x-ray mass-attenuation coefficients of gold, derived quantities between 14 keV and 21 keV and determination of the bond lengths of gold

    International Nuclear Information System (INIS)

    Glover, J L; Chantler, C T; Barnea, Z; Rae, N A; Tran, C Q

    2010-01-01

    The x-ray mass-attenuation coefficients of gold are measured at 91 energies between 14 keV and 21 keV using synchrotron radiation. The measurements are accurate to between 0.08% and 0.1%. The photoelectric mass-absorption coefficients and the imaginary component of the form factors of gold are also determined. The results include the L I edge and are the most accurate and extensive gold dataset available in this energy range. An analysis of the L I edge XAFS showed excellent agreement between the measured and simulated XAFS and yielded highly accurate values of the bond lengths of gold. When our results are compared with earlier measurements and with predictions of major theoretical tabulations, significant discrepancies are noted. The comparison raises questions about the nature of discrepancies between experimental and theoretical values of mass-attenuation coefficients.

  2. 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.

  3. Application of the O-lattice theory for the reconstruction of the high-angle near 90° tilt Si(1 1 0)/(0 0 1) boundary created by wafer bonding

    International Nuclear Information System (INIS)

    Cherkashin, N.; Kononchuk, O.; Reboh, S.; Hÿtch, M.

    2012-01-01

    This work presents an experimental and theoretical identification of defects and morphologies of a high-angle near-90° tilt Si (1 ¯ 10)//(001) boundary created by direct wafer bonding. Two samples with different twist misorientations, between the (1 ¯ 10) layer and the (0 0 1) substrate, were studied using conventional transmission electron microscopy (TEM) and geometric phase analysis of high-resolution TEM images. The O-lattice theory was used for atom reconstruction of the interface along the [11 ¯ 0] sub //[001] lay direction. It is demonstrated that to preserve covalent bonding across the interface, it should consist of {11 ¯ 1} sub,lay //{1 ¯ 12} lay,sub facets intersected by maximum of six {11 ¯ 1} lay,sub planes with three 90° Shockley dislocations per facet. It is shown that a particular atom reconstruction is needed at transition points from one facet to another. The presence or absence of deviation from exact 90° tilt of the layer with respect to the substrate is shown to be related directly to the undulations of the interface. It is demonstrated that the latter has an influence on the Burgers vector of the dislocations adjusting in-plane twist misorientation. A general model for cubic face-centered materials for an arbitrary 〈1 1 0〉 sub,lay tilt interface is proposed, which predicts the net Burgers vector and the spacing between dislocations necessary to realize transition from the lattice of the substrate (layer) to the layer (substrate).

  4. Scoliosis angle

    International Nuclear Information System (INIS)

    Marklund, T.

    1978-01-01

    The most commonly used methods of assessing the scoliotic deviation measure angles that are not clearly defined in relation to the anatomy of the patient. In order to give an anatomic basis for such measurements it is proposed to define the scoliotic deviation as the deviation the vertebral column makes with the sagittal plane. Both the Cobb and the Ferguson angles may be based on this definition. The present methods of measurement are then attempts to measure these angles. If the plane of these angles is parallel to the film, the measurement will be correct. Errors in the measurements may be incurred by the projection. A hypothetical projection, called a 'rectified orthogonal projection', is presented, which correctly represents all scoliotic angles in accordance with these principles. It can be constructed in practice with the aid of a computer and by performing measurements on two projections of the vertebral column; a scoliotic curve can be represented independent of the kyphosis and lordosis. (Auth.)

  5. Fundamental length and relativistic length

    International Nuclear Information System (INIS)

    Strel'tsov, V.N.

    1988-01-01

    It si noted that the introduction of fundamental length contradicts the conventional representations concerning the contraction of the longitudinal size of fast-moving objects. The use of the concept of relativistic length and the following ''elongation formula'' permits one to solve this problem

  6. Physical mechanisms of copper-copper wafer bonding

    International Nuclear Information System (INIS)

    Rebhan, B.; Hingerl, K.

    2015-01-01

    The study of the physical mechanisms driving Cu-Cu wafer bonding allowed for reducing the bonding temperatures below 200 °C. Metal thermo-compression Cu-Cu wafer bonding results obtained at such low temperatures are very encouraging and suggest that the process is possible even at room temperature if some boundary conditions are fulfilled. Sputtered (PVD) and electroplated Cu thin layers were investigated, and the analysis of both metallization techniques demonstrated the importance of decreasing Cu surface roughness. For an equal surface roughness, the bonding temperature of PVD Cu wafers could be even further reduced due to the favorable microstructure. Their smaller grain size enhances the length of the grain boundaries (observed on the surface prior bonding), acting as efficient mass transfer channels across the interface, and hence the grains are able to grow over the initial bonding interface. Due to the higher concentration of random high-angle grain boundaries, this effect is intensified. The model presented is explaining the microstructural changes based on atomic migration, taking into account that the reduction of the grain boundary area is the major driving force to reduce the Gibbs free energy, and predicts the subsequent microstructure evolution (grain growth) during thermal annealing

  7. Flame Length

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Flame length was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The tool...

  8. Bond Issues.

    Science.gov (United States)

    Pollack, Rachel H.

    2000-01-01

    Notes trends toward increased borrowing by colleges and universities and offers guidelines for institutions that are considering issuing bonds to raise money for capital projects. Discussion covers advantages of using bond financing, how use of bonds impacts on traditional fund raising, other cautions and concerns, and some troubling aspects of…

  9. What is a hydrogen bond?

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. What is a hydrogen bond? Precise definition of a hydrogen bond is still elusive!1. Several criteria are listed usually for X-H•••Y, X and Y initially thought to be F, O and N only1. Structural: The X-Y bond length is less than the sum of their van der Waals radii. X-H•••Y is ...

  10. History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis.

    Science.gov (United States)

    Stubbs, Peter W; Walsh, Lee D; D'Souza, Arkiev; Héroux, Martin E; Bolsterlee, Bart; Gandevia, Simon C; Herbert, Robert D

    2018-06-01

    In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle-tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle-tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle-tendon lengths, (b) strong isometric contractions at short muscle-tendon lengths, (c) weak isometric contractions at long muscle-tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle-tendon slack angles and fascicle slack lengths. Contraction at short muscle-tendon lengths caused a mean 13.5 degree (95% CI 11.8-15.0 degree) shift in the muscle-tendon slack angle towards shorter muscle-tendon lengths, and a mean 5 mm (95% CI 2-8 mm) reduction in fascicle slack length, compared to the

  11. Small-angle scattering study of Aspergillus awamori glycoprotein glucoamylase

    International Nuclear Information System (INIS)

    Schmidt, A. E.; Shvetsov, A. V.; Kuklin, A. I.; Lebedev, D. V.; Surzhik, M. A.; Sergeev, V. R.; Isaev-Ivanov, V. V.

    2016-01-01

    Glucoamylase from fungus Aspergillus awamori is glycoside hydrolase that catalyzes the hydrolysis of α-1,4- and α-1,6-glucosidic bonds in glucose polymers and oligomers. This glycoprotein consists of a catalytic domain and a starch-binding domain connected by an O-glycosylated polypeptide chain. The conformation of the linker, the relative arrangement of the domains, and the structure of the full-length enzyme are unknown. The structure of the recombinant glucoamylase GA1 was studied by molecular modelling and small-angle neutron scattering (SANS) methods. The experimental SANS data provide evidence that glucoamylase exists as a monomer in solution and contains a glycoside component, which makes a substantial contribution to the scattering. The model of full-length glucoamylase, which was calculated without taking into account the effect of glycosylation, is consistent with the experimental data and has a radius of gyration of 33.4 ± 0.6 Å

  12. Small-angle scattering study of Aspergillus awamori glycoprotein glucoamylase

    Science.gov (United States)

    Schmidt, A. E.; Shvetsov, A. V.; Kuklin, A. I.; Lebedev, D. V.; Surzhik, M. A.; Sergeev, V. R.; Isaev-Ivanov, V. V.

    2016-01-01

    Glucoamylase from fungus Aspergillus awamori is glycoside hydrolase that catalyzes the hydrolysis of α-1,4- and α-1,6-glucosidic bonds in glucose polymers and oligomers. This glycoprotein consists of a catalytic domain and a starch-binding domain connected by an O-glycosylated polypeptide chain. The conformation of the linker, the relative arrangement of the domains, and the structure of the full-length enzyme are unknown. The structure of the recombinant glucoamylase GA1 was studied by molecular modelling and small-angle neutron scattering (SANS) methods. The experimental SANS data provide evidence that glucoamylase exists as a monomer in solution and contains a glycoside component, which makes a substantial contribution to the scattering. The model of full-length glucoamylase, which was calculated without taking into account the effect of glycosylation, is consistent with the experimental data and has a radius of gyration of 33.4 ± 0.6 Å.

  13. Small-angle scattering study of Aspergillus awamori glycoprotein glucoamylase

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, A. E., E-mail: schmidt@omrb.pnpi.spb.ru; Shvetsov, A. V. [National Research Center “Kurchatov Institute”, Konstantinov Petersburg Nuclear Physics Institute (Russian Federation); Kuklin, A. I. [Joint Institute for Nuclear Research (Russian Federation); Lebedev, D. V.; Surzhik, M. A.; Sergeev, V. R.; Isaev-Ivanov, V. V. [National Research Center “Kurchatov Institute”, Konstantinov Petersburg Nuclear Physics Institute (Russian Federation)

    2016-01-15

    Glucoamylase from fungus Aspergillus awamori is glycoside hydrolase that catalyzes the hydrolysis of α-1,4- and α-1,6-glucosidic bonds in glucose polymers and oligomers. This glycoprotein consists of a catalytic domain and a starch-binding domain connected by an O-glycosylated polypeptide chain. The conformation of the linker, the relative arrangement of the domains, and the structure of the full-length enzyme are unknown. The structure of the recombinant glucoamylase GA1 was studied by molecular modelling and small-angle neutron scattering (SANS) methods. The experimental SANS data provide evidence that glucoamylase exists as a monomer in solution and contains a glycoside component, which makes a substantial contribution to the scattering. The model of full-length glucoamylase, which was calculated without taking into account the effect of glycosylation, is consistent with the experimental data and has a radius of gyration of 33.4 ± 0.6 Å.

  14. Fundamental length

    International Nuclear Information System (INIS)

    Pradhan, T.

    1975-01-01

    The concept of fundamental length was first put forward by Heisenberg from purely dimensional reasons. From a study of the observed masses of the elementary particles known at that time, it is sumrised that this length should be of the order of magnitude 1 approximately 10 -13 cm. It was Heisenberg's belief that introduction of such a fundamental length would eliminate the divergence difficulties from relativistic quantum field theory by cutting off the high energy regions of the 'proper fields'. Since the divergence difficulties arise primarily due to infinite number of degrees of freedom, one simple remedy would be the introduction of a principle that limits these degrees of freedom by removing the effectiveness of the waves with a frequency exceeding a certain limit without destroying the relativistic invariance of the theory. The principle can be stated as follows: It is in principle impossible to invent an experiment of any kind that will permit a distintion between the positions of two particles at rest, the distance between which is below a certain limit. A more elegant way of introducing fundamental length into quantum theory is through commutation relations between two position operators. In quantum field theory such as quantum electrodynamics, it can be introduced through the commutation relation between two interpolating photon fields (vector potentials). (K.B.)

  15. Parental Bonding

    Directory of Open Access Journals (Sweden)

    T. Paul de Cock

    2014-08-01

    Full Text Available Estimating the early parent–child bonding relationship can be valuable in research and practice. Retrospective dimensional measures of parental bonding provide a means for assessing the experience of the early parent–child relationship. However, combinations of dimensional scores may provide information that is not readily captured with a dimensional approach. This study was designed to assess the presence of homogeneous groups in the population with similar profiles on parental bonding dimensions. Using a short version of the Parental Bonding Instrument (PBI, three parental bonding dimensions (care, authoritarianism, and overprotection were used to assess the presence of unobserved groups in the population using latent profile analysis. The class solutions were regressed on 23 covariates (demographics, parental psychopathology, loss events, and childhood contextual factors to assess the validity of the class solution. The results indicated four distinct profiles of parental bonding for fathers as well as mothers. Parental bonding profiles were significantly associated with a broad range of covariates. This person-centered approach to parental bonding has broad utility in future research which takes into account the effect of parent–child bonding, especially with regard to “affectionless control” style parenting.

  16. NMR-based metabolomics reveals that conjugated double bond content and lipid storage efficiency in HepG2 cells are affected by fatty acid cis/trans configuration and chain length

    DEFF Research Database (Denmark)

    Najbjerg, Heidi; Young, Jette F; Bertram, Hanne Christine S.

    2011-01-01

    from conjugated double bonds (5.65, 5.94, and 6.28 ppm) in cells exposed to vaccenic acid, revealing that vaccenic acid upon uptake by the HepG2 cells is converted into a conjugated fatty acid. Upon exposure of the HepG2 cells to either butyric acid (C4:0), caproic acid (C6:0), lauric acid (C12...

  17. 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.

  18. Raman spectroscopy of supported chromium oxide catalysts : determination of chromium-oxygen bond distances and bond orders

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.

    1996-01-01

    An empirical correlation is described for relating Raman stretching frequencies of chromium—oxygen (Cr—O) bonds to their bond lengths in chromium oxide reference compounds. An exponential fit of crystallographically determined Cr—O bond lengths to Cr—O Raman symmetric stretching frequencies

  19. Directionality of Cation/Molecule Bonding in Lewis Bases Containing the Carbonyl Group.

    Science.gov (United States)

    Valadbeigi, Younes; Gal, Jean-François

    2017-09-14

    Relationship between the C═O-X + (X = H, Li, Na, K, Al, Cu) angle and covalent characteristic of the X + -M (M = CH 2 O, CH 3 CHO, acetone, imidazol-2-one (C 2 H 2 N 2 O), cytosine, γ-butyrolactone) was investigated, theoretically. The calculated electron densities ρ at the bond critical points revealed that the covalency of the M-X + interaction depended on the nature of the cation and varied as H + > Cu + > Al + > Li + > Na + > K + . The alkali cations tended to participate in electrostatic interactions and aligned with the direction of the molecule dipole or local dipole of C═O group to form linear C═O-X geometries. Because of overlapping with lone-pair electrons of the sp 2 carbonyl oxygen, the H + and Cu + formed a bent C═O-X angle. Al + displayed an intermediate behavior; the C═O-Al angle was 180° in [CH 2 O/Al] + (mainly electrostatic), but when the angle was bent (146°) under the effect of local dipole of an adjacent imine group in cytosine, the covalency of the CO-Al + interaction increased. The C═O-X angles in M/X + adduct ions were scanned in different O-X bond lengths. It was found that the most favorable C═O-X angle depended on the O-X bond length. This dependency was attributed to variation of covalent and electrostatic contributions with O-X distance. In addition, the structures of [CH 2 S/X] + and [CH 2 Se/X] + were studied, and only bent C═S-X and C═Se-X angles were obtained for all cations, although the dipole vectors of CH 2 S and CH 2 Se coincide with the C═S and C═Se bonds. The bending of the C═S-X and C═Se-X angles was attributed to the covalent characteristic of S-X and Se-X interactions due to high polarizability of S and Se atoms.

  20. Kondo length in bosonic lattices

    Science.gov (United States)

    Giuliano, Domenico; Sodano, Pasquale; Trombettoni, Andrea

    2017-09-01

    Motivated by the fact that the low-energy properties of the Kondo model can be effectively simulated in spin chains, we study the realization of the effect with bond impurities in ultracold bosonic lattices at half filling. After presenting a discussion of the effective theory and of the mapping of the bosonic chain onto a lattice spin Hamiltonian, we provide estimates for the Kondo length as a function of the parameters of the bosonic model. We point out that the Kondo length can be extracted from the integrated real-space correlation functions, which are experimentally accessible quantities in experiments with cold atoms.

  1. Bond-Slip Relationship for CFRP Sheets Externally Bonded to Concrete under Cyclic Loading.

    Science.gov (United States)

    Li, Ke; Cao, Shuangyin; Yang, Yue; Zhu, Juntao

    2018-02-26

    The objective of this paper was to explore the bond-slip relationship between carbon fiber-reinforced polymer (CFRP) sheets and concrete under cyclic loading through experimental and analytical approaches. Modified beam tests were performed in order to gain insight into the bond-slip relationship under static and cyclic loading. The test variables are the CFRP-to-concrete width ratio, and the bond length of the CFRP sheets. An analysis of the test results in this paper and existing test results indicated that the slope of the ascending segment of the bond-slip curve decreased with an increase in the number of load cycles, but the slip corresponding to the maximum shear stress was almost invariable as the number of load cycles increased. In addition, the rate of reduction in the slope of the ascending range of the bond-slip curve during cyclic loading decreased as the concrete strength increased, and increased as the load level or CFRP-to-concrete width ratio enhanced. However, these were not affected by variations in bond length if the residual bond length was longer than the effective bond length. A bilinear bond-slip model for CFRP sheets that are externally bonded to concrete under cyclic loading, which considered the effects of the cyclic load level, concrete strength, and CFRP-to-concrete ratio, was developed based on the existing static bond-slip model. The accuracy of this proposed model was verified by a comparison between this proposed model and test results.

  2. Bonds Boom.

    Science.gov (United States)

    Reynolds, Cathryn

    1989-01-01

    The combined effect of the "Serrano" decision and Proposition 13 left California school districts with aging, overcrowded facilities. Chico schools won a $18.5 million general obligation bond election for facilities construction. With $11 billion needed for new school construction, California will need to tap local sources. A sidebar…

  3. Diffusion bonding

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1976-01-01

    A method is described for joining beryllium to beryllium by diffusion bonding. At least one surface portion of at least two beryllium pieces is coated with nickel. A coated surface portion is positioned in a contiguous relationship with another surface portion and subjected to an environment having an atmosphere at a pressure lower than ambient pressure. A force is applied on the beryllium pieces for causing the contiguous surface portions to abut against each other. The contiguous surface portions are heated to a maximum temperature less than the melting temperature of the beryllium, and the applied force is decreased while increasing the temperature after attaining a temperature substantially above room temperature. A portion of the applied force is maintained at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions

  4. Glaucoma, Open-Angle

    Science.gov (United States)

    ... Home » Statistics and Data » Glaucoma, Open-angle Listen Glaucoma, Open-angle Open-angle Glaucoma Defined In open-angle glaucoma, the fluid passes ... 2010 2010 U.S. Age-Specific Prevalence Rates for Glaucoma by Age and Race/Ethnicity The prevalence of ...

  5. A study on the contact angles of a water droplet on smooth and rough solid surfaces

    International Nuclear Information System (INIS)

    Park, Ju Young; Ha, Man Yeong; Choi, Ho Jin; Hong, Seung Do; Yoon, Hyun Sik

    2011-01-01

    We investigated the wetting characteristics such as contact angle, wetting radius and topography of water droplets on smooth and random solid surfaces. Molecular dynamic simulation is employed to analyze the wetting behavior of water droplets on smooth and rough surfaces by considering different potential energy models of bond, angle, Lennard-Jones and Coulomb to calculate the interacting forces between water molecules. The Lennard-Jones potential energy model is adopted as an interaction model between water molecules and solid surface atoms. The randomly rough surface is generated by changing the standard deviation of roughness height from 1 A to 3 A with the fixed autocorrelation length. The size of water droplet considered is in the range from 2,000 to 5,000 molecules. The contact angles increase generally with increasing number of water molecules. For a hydrophobic surface whose characteristic energy is 0.1 kcal/mol, the contact angles depend rarely on the standard deviation of the roughness height. However, when the surface energy is 0.5 and 1.0 kcal/mol, the contact angles depend on both the roughness height of surfaces and droplet size

  6. Crystal structure, vibrational spectra and DFT studies of hydrogen bonded 1,2,4-triazolium hydrogenselenate

    Science.gov (United States)

    Arjunan, V.; Thirunarayanan, S.; Marchewka, M. K.; Mohan, S.

    2017-10-01

    The new hydrogen bonded molecular complex 1,2,4-triazolium hydrogenselenate (THS) is prepared by the reaction of 1H-1,2,4-triazole and selenic acid. This complex is stabilised by N-H⋯O and C-H⋯O hydrogen bonding and electrostatic attractive forces between 1H and 1,2,4-triazolium cations and hydrogen selenate anions. The XRD studies revealed that intermolecular proton transfer occur from selenic acid to 1H-1,2,4-triazole molecule, results in the formation of 1,2,4-triazolium hydrogenselenate which contains 1,2,4-triazolium cations and hydrogenselenate anions. The molecular structure of THS crystal has also been optimised by using Density Functional Theory (DFT) using B3LYP/cc-pVTZ and B3LYP/6-311++G** methods in order to find the whole characteristics of the molecular complex. The theoretical structural parameters such as bond length, bond angle and dihedral angle determined by DFT methods are well agreed with the XRD parameters. The atomic charges and thermodynamic properties are also calculated and analysed. The energies of frontier molecular orbitals HOMO, LUMO, HOMO-1, LUMO+1 and LUMO-HUMO energy gap are calculated to understand the kinetic stability and chemical reactivity of the molecular complex. The natural bond orbital analysis (NBO) has been performed in order to study the intramolecular bonding interactions and delocalisation of electrons. These intra molecular charge transfer may induce biological activities such as antimicrobials, antiinflammatory, antifungal etc. The complete vibrational assignments of THS have been performed by using FT-IR and FT-Raman spectra.

  7. Variable angle asymmetric cut monochromator

    International Nuclear Information System (INIS)

    Smither, R.K.; Fernandez, P.B.

    1993-09-01

    A variable incident angle, asymmetric cut, double crystal monochromator was tested for use on beamlines at the Advanced Photon Source (APS). For both undulator and wiggler beams the monochromator can expand area of footprint of beam on surface of the crystals to 50 times the area of incident beam; this will reduce the slope errors by a factor of 2500. The asymmetric cut allows one to increase the acceptance angle for incident radiation and obtain a better match to the opening angle of the incident beam. This can increase intensity of the diffracted beam by a factor of 2 to 5 and can make the beam more monochromatic, as well. The monochromator consists of two matched, asymmetric cut (18 degrees), silicon crystals mounted so that they can be rotated about three independent axes. Rotation around the first axis controls the Bragg angle. The second rotation axis is perpendicular to the diffraction planes and controls the increase of the area of the footprint of the beam on the crystal surface. Rotation around the third axis controls the angle between the surface of the crystal and the wider, horizontal axis for the beam and can make the footprint a rectangle with a minimum. length for this area. The asymmetric cut is 18 degrees for the matched pair of crystals, which allows one to expand the footprint area by a factor of 50 for Bragg angles up to 19.15 degrees (6 keV for Si[111] planes). This monochromator, with proper cooling, will be useful for analyzing the high intensity x-ray beams produced by both undulators and wigglers at the APS

  8. Small angle spectrometers: Summary

    International Nuclear Information System (INIS)

    Courant, E.; Foley, K.J.; Schlein, P.E.

    1986-01-01

    Aspects of experiments at small angles at the Superconducting Super Collider are considered. Topics summarized include a small angle spectrometer, a high contingency spectrometer, dipole and toroid spectrometers, and magnet choices

  9. Contact Angle Goniometer

    Data.gov (United States)

    Federal Laboratory Consortium — Description:The FTA32 goniometer provides video-based contact angle and surface tension measurement. Contact angles are measured by fitting a mathematical expression...

  10. Telomere Length and Mortality

    DEFF Research Database (Denmark)

    Kimura, Masayuki; Hjelmborg, Jacob V B; Gardner, Jeffrey P

    2008-01-01

    Leukocyte telomere length, representing the mean length of all telomeres in leukocytes, is ostensibly a bioindicator of human aging. The authors hypothesized that shorter telomeres might forecast imminent mortality in elderly people better than leukocyte telomere length. They performed mortality...

  11. Behavior of Tilted Angle Shear Connectors

    Science.gov (United States)

    Khorramian, Koosha; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.

    2015-01-01

    According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type. PMID:26642193

  12. Behavior of Tilted Angle Shear Connectors.

    Directory of Open Access Journals (Sweden)

    Koosha Khorramian

    Full Text Available According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type.

  13. The resection angle in apical surgery

    DEFF Research Database (Denmark)

    von Arx, Thomas; Janner, Simone F M; Jensen, Simon S

    2016-01-01

    OBJECTIVES: The primary objective of the present radiographic study was to analyse the resection angle in apical surgery and its correlation with treatment outcome, type of treated tooth, surgical depth and level of root-end filling. MATERIALS AND METHODS: In the context of a prospective clinical...... study, cone beam computed tomography (CBCT) scans were taken before and 1 year after apical surgery to measure the angle of the resection plane relative to the longitudinal axis of the root. Further, the surgical depth (distance from the buccal cortex to the most lingual/palatal point of the resection...... or with the retrofilling length. CONCLUSIONS: Statistically significant differences were observed comparing resection angles of different tooth groups. However, the angle had no significant effect on treatment outcome. CLINICAL RELEVANCE: Contrary to common belief, the resection angle in maxillary anterior teeth...

  14. Bond behavior between CFRP sheet and concrete. Part 2. Improvement of bond strength by out-of plane confinement; CFRP sheet to concrete no fuchaku kyodo (2). Mengai kosoku ni yoru fuchaku tairyoku no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Y.; Kimura, K.; Kobatake, Y. [Obayashigumi Research Inst., Tokyo (Japan)

    1998-07-30

    Behavior of phase at the bond interface between CFRP sheet and concrete is modeled basing on the result of anchoring experiment, and specimens are subjected to finite element analysis to investigate necessary confining stress and anchoring length. Improvement of bonding strength is confirmed by providing lateral sheet for anchoring on the sheet bonded on concrete. The out-of-plane stress acted on the sheet and the out-of-plane displacement during confinement in the experiment are estimated as average 0.5MPa and 0.16mm, respectively. Providing appropriate angle to a two-node joint and setting proper stress/deformation relation of springs crossing each other, the behavior of the phase at the bond interface subjected to out-of-plane confinement is modeled. The maximum bond stress is improved from 4.56MPa to 5.10MPa, and the area where the bond stress becomes larger than 4.56MPa increases from 25mm to 30mm. To anchor the sheet employed in this experiment, larger than 30mm out-of-plane confining stress of 0.5MPa must be provided in the direction of fiber. 16 refs., 17 figs., (plus 1 appended fig.), 3 tabs.

  15. Bond strength of masonry

    NARCIS (Netherlands)

    Pluijm, van der R.; Vermeltfoort, A.Th.

    1992-01-01

    Bond strength is not a well defined property of masonry. Normally three types of bond strength can be distinguished: - tensile bond strength, - shear (and torsional) bond strength, - flexural bond strength. In this contribution the behaviour and strength of masonry in deformation controlled uniaxial

  16. Thumb rule of visual angle: a new confirmation.

    Science.gov (United States)

    Groot, C; Ortega, F; Beltran, F S

    1994-02-01

    The classical thumb rule of visual angle was reexamined. Hence, the visual angle was measured as a function of a thumb's width and the distance between eye and thumb. The measurement of a thumb's width when held at arm's length was taken on 67 second-year students of psychology. The visual angle was about 2 degrees as R. P. O'Shea confirmed in 1991. Also, we confirmed a linear relationship between the size of a thumb's width at arm's length and the visual angle.

  17. Proposal of new bonding technique 'Instantaneous Liquid Phase (ILP) Bonding'

    International Nuclear Information System (INIS)

    Zhang, Yue-Chang; Nakagawa, Hiroji; Matsuda, Fukuhisa.

    1987-01-01

    A new bonding technique named ''Instantaneous Liquid Phase (ILP) bonding'' suitable mainly for welding dissimilar materials was proposed by which instantaneous melting of one or two of the faying surfaces is utilized. The processes of ILP bonding are mainly consisted of three stages, namely the first stage forming thin liquid layer by rapid heating, the second stage joining both specimens by thin liquid layer, and the third stage cooling the specimens rapidly to avoid the formation of brittle layer. The welding temperatures of the specimens to be welded in ILP bonding are generally differentiated from each other. ILP bonding was applied for a variety of combinations of dissimilar materials of aluminum, aluminum alloys, titanium, titanium alloy, carbon steel, austenitic stainless steel, copper and tungsten, and for similar materials of stainless steel and nickel-base alloy. There were no microvoids in these welding joints, and the formation of brittle layer at the bonding interface was suppressed. The welded joints of Al + Ti, Cu + carbon steel and Cu + austenitic stainless steel showed the fracture in base metal having lower tensile strength. Further, the welded joints of Al + carbon steel, Al alloy + Ti, Al alloy + carbon steel or + austenitic stainless steel, Ti + carbon steel or + austenitic stainless steel showed better tensile properties in the comparison with diffusion welding. Furthermore, ILP bonding was available for welding same materials susceptible to hot cracking. Because of the existence of liquid layer, the welding pressure required was extremely low, and preparation of faying surface by simple tooling or polishing by no.80 emery paper was enough. The change in specimen length before and after welding was relatively little, only depending on the thickness of liquid layer. The welding time was very short, and thus high welding efficiency was obtained. (author)

  18. Understanding Bonds - Denmark

    DEFF Research Database (Denmark)

    Rimmer, Nina Røhr

    2016-01-01

    Undervisningsmateriale. A bond is a debt security, similar to an ”I Owe You document” (IOU). When you purchase a bond, you are lending money to a government, municipality, corporation, federal agency or other entity known as the issuer. In return for the loan, the issuer promises to pay you...... 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...... securities and foreign government bonds....

  19. Quantum mechanics models of the methanol dimer: OH⋯O hydrogen bonds of β-d-glucose moieties from crystallographic data.

    Science.gov (United States)

    Cintrón, Michael Santiago; Johnson, Glenn P; French, Alfred D

    2017-04-18

    The interaction of two methanol molecules, simplified models of carbohydrates and cellulose, was examined using a variety of quantum mechanics (QM) levels of theory. Energy plots for hydrogen bonding distance (H⋯O) and angle (OH⋯O) were constructed. All but two experimental structures were located in stabilized areas on the vacuum phase energy plots. Each of the 399 models was analyzed with Bader's atoms-in-molecules (AIM) theory, which showed a widespread ability by the dimer models to form OH⋯O hydrogen bonds that have bond paths and Bond Critical Points. Continuum solvation calculations suggest that a portion of the energy-stabilized structures could occur in the presence of water. A survey of the Cambridge Structural Database (CSD) for all donor-acceptor interactions in β-D-glucose moieties examined the similarities and differences among the hydroxyl groups and acetal oxygen atoms that participate in hydrogen bonds. Comparable behavior was observed for the O2H, O3H, O4H, and O6H hydroxyls, acting either as acceptors or donors. Ring O atoms showed distinct hydrogen bonding behavior that favored mid-length hydrogen bonds. Published by Elsevier Ltd.

  20. 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...

  1. Optimal reconstruction angles

    International Nuclear Information System (INIS)

    Cook, G.O. Jr.; Knight, L.

    1979-07-01

    The question of optimal projection angles has recently become of interest in the field of reconstruction from projections. Here, studies are concentrated on the n x n pixel space, where literative algorithms such as ART and direct matrix techniques due to Katz are considered. The best angles are determined in a Gauss--Markov statistical sense as well as with respect to a function-theoretical error bound. The possibility of making photon intensity a function of angle is also examined. Finally, the best angles to use in an ART-like algorithm are studied. A certain set of unequally spaced angles was found to be preferred in several contexts. 15 figures, 6 tables

  2. Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of 4-chlorobenzothioamide

    Science.gov (United States)

    Çırak, Çağrı; Sert, Yusuf; Ucun, Fatih

    2013-09-01

    In the present work, the experimental and theoretical vibrational spectra of 4-chlorobenzothioamide were investigated. The FT-IR (400-4000 cm-1) and μ-Raman spectra (100-4000 cm-1) of 4-chlorobenzothioamide in the solid phase were recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared and Raman intensities of the title molecule in the ground state were calculated using ab initio Hartree-Fock and density functional theory (B3LYP) methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and the theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 4-chlorobenzothioamide was also simulated to evaluate the effect of intermolecular hydrogen bonding on the vibrational frequencies. It was observed that the Nsbnd H stretching modes shifted to lower frequencies, while the in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular Nsbnd H⋯S hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented.

  3. Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of a biomolecule: 5-Hydroxymethyluracil

    Science.gov (United States)

    Çırak, Çağrı; Sert, Yusuf; Ucun, Fatih

    2014-06-01

    In the present work, the experimental and theoretical vibrational spectra of 5-hydroxymethyluracil were investigated. The FT-IR (4000-400 cm-1) spectrum of the molecule in the solid phase was recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared intensities of the title molecule in the ground state were calculated using density functional B3LYP and M06-2X methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data, and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 5-hydroxymethyluracil molecule was also simulated to evaluate the effect of intermolecular hydrogen bonding on its vibrational frequencies. It was observed that the Nsbnd H stretching modes shifted to lower frequencies, while its in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular Nsbnd H⋯O hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented.

  4. A modification of the Schomaker—Stevenson rule for prediction of single bond distances

    Science.gov (United States)

    Blom, Richard; Haaland, Arne

    1985-04-01

    A modification of the Schomaker—Stevenson rule: ?c = 8.5 pm, n = 1.4, significantly reduces the discrepancy between experimental calculated bond lengths for every polar bonds between main group elements.

  5. Study on the Connecting Length of CFRP

    Science.gov (United States)

    Liu, Xiongfei; Li, Yue; Li, Zhanguo

    2018-05-01

    The paper studied the varying mode of shear stress in the connecting zone of CFRP. Using epoxy resin (EP) as bond material, performance of specimens with different connecting length of CFRP was tested to obtain the conclusion. CFRP-confined concrete column was tested subsequently to verify the conclusion. The results show that: (1) The binding properties of modified epoxy resin with CFRP is good; (2) As the connecting length increased, the ultimate tensile strength of CFRP increased as well in the range of the experiment parameters; (3) Tensile strength of CFRP can reach the ultimate strength when the connecting length is 90mm;(4) The connecting length of 90mm of CFRP meet the reinforcement requirements.

  6. Angles in hyperbolic lattices

    DEFF Research Database (Denmark)

    Risager, Morten S.; Södergren, Carl Anders

    2017-01-01

    It is well known that the angles in a lattice acting on hyperbolic n -space become equidistributed. In this paper we determine a formula for the pair correlation density for angles in such hyperbolic lattices. Using this formula we determine, among other things, the asymptotic behavior of the den......It is well known that the angles in a lattice acting on hyperbolic n -space become equidistributed. In this paper we determine a formula for the pair correlation density for angles in such hyperbolic lattices. Using this formula we determine, among other things, the asymptotic behavior...... of the density function in both the small and large variable limits. This extends earlier results by Boca, Pasol, Popa and Zaharescu and Kelmer and Kontorovich in dimension 2 to general dimension n . Our proofs use the decay of matrix coefficients together with a number of careful estimates, and lead...

  7. Adsorption site and structure determination of c(2x2) N{sub 2}/Ni(100) using angle-resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors have determined the atomic spatial structure of c(2x2) N2Ni(100) with Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) from the nitrogen 1s core level using monochromatized x-rays from beamline 6.1 at SSRL and beamline 9.3.2 at the ALS. The chemically shifted N 1s peak intensities were summed together to obtain ARPEFS curves for both nitrogen atoms in the molecule. They used a new, highly-optimized program based on the Rehr-Albers scattering matrix formalism to find the adsorption site and to quantitatively determine the bond-lengths. The nitrogen molecule stands upright at an atop site, with a N-Ni bond length of 2.25(1) {angstrom}, a N-N bond length of 1.10(7) {angstrom}, and a first layer Ni-Ni spacing of 1.76(4) {angstrom}. The shake-up peak shows an identical ARPEFS diffraction pattern, confirming its intrinsic nature and supporting a previous use of this feature to decompose the peak into contributions from the chemically inequivalent nitrogen atoms. Comparison to a previously published theoretical treatment of N-N-Ni and experimental structures of analogous adsorbate systems demonstrates the importance of adsorbate-adsorbate interactions in weakly chemisorbed systems.

  8. Neutron spin echo scattering angle measurement (SESAME)

    International Nuclear Information System (INIS)

    Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A.

    2005-01-01

    We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-μm-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for

  9. Characterization of porous materials by small-angle scattering

    Indian Academy of Sciences (India)

    With the availability of ultra small-angle scattering instruments, one can investigate porous materials in the sub-micron length scale. Because of the increased accessible length scale vis-a-vis the multiple scattering effect, conventional data analysis procedures based on single scattering approximation quite often fail.

  10. The analysis of projected fission track lengths

    International Nuclear Information System (INIS)

    Laslett, G.M.; Galbraith, R.F.; Green, P.F.

    1994-01-01

    This article deals with the question of how features of the thermal history can be estimated from projected track length measurements, i.e. lengths of the remaining parts of tracks that have intersected a surface, projected onto that surface. The appropriate mathematical theory is described and used to provide a sound basis both for understanding the nature of projected length measurements and for analysing observed data. The estimation of thermal history parameters corresponding to the current temperature, the maximum palaeotemperature and the time since cooling, is studied using laboratory data and simulations. In general the information contained in projected track lengths and angles is fairly limited, compared, for example, with that from a much smaller number of confined tracks, though we identify some circumstances when such measurements may be useful. Also it is not straightforward to extract the information and simple ad hoc estimation methods are generally inadequate. (author)

  11. Bonding with Your Baby

    Science.gov (United States)

    ... the future bonding of the child and parent. Adoptive parents may be concerned about bonding with their ... general emotional support. And it's OK to ask family members and friends for help in the days — ...

  12. Australia's Bond Home Bias

    OpenAIRE

    Anil V. Mishra; Umaru B. Conteh

    2014-01-01

    This paper constructs the float adjusted measure of home bias and explores the determinants of bond home bias by employing the International Monetary Fund's high quality dataset (2001 to 2009) on cross-border bond investment. The paper finds that Australian investors' prefer investing in countries with higher economic development and more developed bond markets. Exchange rate volatility appears to be an impediment for cross-border bond investment. Investors prefer investing in countries with ...

  13. Telomere length analysis.

    Science.gov (United States)

    Canela, Andrés; Klatt, Peter; Blasco, María A

    2007-01-01

    Most somatic cells of long-lived species undergo telomere shortening throughout life. Critically short telomeres trigger loss of cell viability in tissues, which has been related to alteration of tissue function and loss of regenerative capabilities in aging and aging-related diseases. Hence, telomere length is an important biomarker for aging and can be used in the prognosis of aging diseases. These facts highlight the importance of developing methods for telomere length determination that can be employed to evaluate telomere length during the human aging process. Telomere length quantification methods have improved greatly in accuracy and sensitivity since the development of the conventional telomeric Southern blot. Here, we describe the different methodologies recently developed for telomere length quantification, as well as their potential applications for human aging studies.

  14. 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.

  15. 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

  16. The quadriceps angle

    DEFF Research Database (Denmark)

    Miles, James Edward; Frederiksen, Jane V.; Jensen, Bente Rona

    2012-01-01

    : Pelvic limbs from red foxes (Vulpes vulpes). METHODS: Q angles were measured on hip dysplasia (HD) and whole limb (WL) view radiographs of each limb between the acetabular rim, mid-point (Q1: patellar center, Q2: femoral trochlea), and tibial tuberosity. Errors of 0.5-2.0 mm at measurement landmarks...

  17. open angle glaucoma (poag)?

    African Journals Online (AJOL)

    there is a build up of pressure due to poor outflow of aqueous humor. The outflow obstruction could occur at the trabecular meshwork of the anterior chamber angle or subsequently in the episcleral vein due to raised venous pressure. Such build up of pressure results in glaucoma . Elevated intraocular pressure remains the ...

  18. The lateral angle revisited

    DEFF Research Database (Denmark)

    Morgan, Jeannie; Lynnerup, Niels; Hoppa, R.D.

    2013-01-01

    measurements taken from computed tomography (CT) scans. Previous reports have observed that the lateral angle size in females is significantly larger than in males. The method was applied to an independent series of 77 postmortem CT scans (42 males, 35 females) to validate its accuracy and reliability...... method appears to be of minimal practical use in forensic anthropology and archeology....

  19. At Right Angles

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 17; Issue 9. At Right Angles. Shailesh A Shirali. Information and Announcements Volume 17 Issue 9 September 2012 pp 920-920. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/017/09/0920-0920 ...

  20. Wide angle isotope separator

    International Nuclear Information System (INIS)

    Kantrowitz, A.

    1976-01-01

    A method and apparatus is described for particle separation. The method uses a wide angle radially expanding vapor of a particle mixture. In particular, selective ionization of one isotope type in the particle mixture is produced in a multichamber separator and the ionized isotope type is accelerated out of the path of the vapor expansion for separate collection

  1. Telomere length and depression

    DEFF Research Database (Denmark)

    Wium-Andersen, Marie Kim; Ørsted, David Dynnes; Rode, Line

    2017-01-01

    BACKGROUND: Depression has been cross-sectionally associated with short telomeres as a measure of biological age. However, the direction and nature of the association is currently unclear. AIMS: We examined whether short telomere length is associated with depression cross-sectionally as well...... as prospectively and genetically. METHOD: Telomere length and three polymorphisms, TERT, TERC and OBFC1, were measured in 67 306 individuals aged 20-100 years from the Danish general population and associated with register-based attendance at hospital for depression and purchase of antidepressant medication....... RESULTS: Attendance at hospital for depression was associated with short telomere length cross-sectionally, but not prospectively. Further, purchase of antidepressant medication was not associated with short telomere length cross-sectionally or prospectively. Mean follow-up was 7.6 years (range 0...

  2. Effect of Bonding Pressure and Bonding Time on the Tensile Properties of Cu-Foam / Cu-Plate Diffusion Bonded Joint

    International Nuclear Information System (INIS)

    Kim, Sang-Ho; Heo, Hoe-Jun; Kang, Chung-Yun; Yoon, Tae-Jin

    2016-01-01

    Open cell Cu foam, which has been widely utilized in various industries because of its high thermal conductivity, lightweight and large surface area, was successfully joined with Cu plate by diffusion bonding. To prevent excessive deformation of the Cu foam during bonding process, the bonding pressure should be lower than 500 kPa at 800 ℃ for 60 min and bonding pressure should be lowered with increasing holding time. The bonding strength was evaluated by tensile tests. The tensile load of joints increased with the bonding pressure and holding time. In the case of higher bonding pressure or time, the bonded length at the interface was usually longer than the cross-sectional length of the foam, so fracture occurred at the foam. For the same reason, base metal (foam) fracture mainly occurred at the node-plate junction rather than in the strut-plate junction because the bonded surface area of the node was relatively larger than that of the strut.

  3. The structure of formate on TiO{sub 2}(110) by scanned-energy and scanned-angle photoelectron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Thevuthasan, S.; Kim, Y.J.; Herman, G.S. [Pacific Northwest National Laboratory, Richland, WA (United States)] [and others

    1997-04-01

    There is a considerable interest in understanding the interaction of small organic molecules with oxide surfaces. The chemistry of formate interactions with TiO{sub 2}(110) has been investigated by several groups, but there is little information on the structure of the adsorbate/surface complex. Recently the authors combined high-energy x-ray photoelectron diffraction (XPD) measurements at PNNL with low-energy scanned-angle and scanned-energy photoelectron diffraction measurements at the ALS to investigate the structure of the formate ion on TiO{sub 2}(110) in detail. The high-energy XPD results reveal that formate binds through the oxygens in a bidentate fashion to Ti cation rows along the [001] direction with an O-C-O bond angle of about 126{degrees}. Low-energy photoelectron diffraction data, which is briefly described below, was used to identify the specific bonding geometry, including the bond length between the Ti cation and the oxygen in the formate.

  4. Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces.

    Science.gov (United States)

    Chen, Szu-Ying; Kaufman, Yair; Schrader, Alex M; Seo, Dongjin; Lee, Dong Woog; Page, Steven H; Koenig, Peter H; Isaacs, Sandra; Gizaw, Yonas; Israelachvili, Jacob N

    2017-09-26

    Measuring truly equilibrium adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 nm/s. We have measured advancing-receding contact angles and loading-unloading adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, ±V, focusing on the thermodynamic limit of ±V → 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) adhesion energies and contact angles suitable for both (i) dynamic adhesion measurements using the classic Johnson-Kendall-Roberts (JKR, 1971) theory of "contact mechanics" and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from V ≈ 10 mm/s to 1 nm/s, where in all cases but one, the advancing (V > 0) and receding (V contact angles converged toward the same theoretical (thermodynamic) values as V → 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular length/dimension or area and characteristic bond formation/rupture lifetime or velocity. Our theoretical and experimental methods and results unify previous kinetic theories of adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, quasi-static, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., viscous, and inertial effects do not play a role at the

  5. Factors influencing bonding fixed restorations

    Directory of Open Access Journals (Sweden)

    Medić Vesna

    2008-01-01

    Full Text Available INTRODUCTION Crown displacement often occurs because the features of tooth preparations do not counteract the forces directed against restorations. OBJECTIVE The purpose of this study was to evaluate the effect of preparation designs on retention and resistance of fixed restorations. METHOD The study was performed on 64 differently sized stainless steel dies. Also, caps which were used for evaluated retention were made of stainless steel for each die. After cementing the caps on experimental dies, measuring of necessary tensile forces to separate cemented caps from dies was done. Caps, which were made of a silver-palladium alloy with a slope of 60° to the longitudinal axis formed on the occlusal surface, were used for evaluating resistance. A sudden drop in load pressure recorded by the test machine indicated failure for that cap. RESULTS A significant difference was found between the tensile force required to remove the caps from the dies with different length (p<0.05 and different taper (p<0.01. The greatest retentive strengths (2579.2 N and 2989.8 N were noticed in experimental dies with the greatest length and smallest taper. No statistically significant (p>0.05 differences were found between tensile loads for caps cemented on dies with different diameter. Although there was an apparent slight increase in resistance values for caps on dies with smaller tapers, the increase in resistance for those preparation designs was not statistically significant. There was a significant difference among the resistance values for caps on dies with different length (p<0.01 and diameter (p<0.05. CONCLUSION In the light of the results obtained, it could be reasonably concluded that retention and resistance of the restoration is in inverse proportion to convergence angle of the prepared teeth. But, at a constant convergence angle, retention and resistance increase with rising length and diameter.

  6. Crystal structure and hydrogen bonding in N-(1-deoxy-β-d-fructopyranos-1-yl-2-aminoisobutyric acid

    Directory of Open Access Journals (Sweden)

    Valeri V. Mossine

    2018-01-01

    Full Text Available The title compound, alternatively called d-fructose-2-aminoisobutyric acid (FruAib, C10H19NO7, (I, crystallizes exclusively in the β-pyranose form, with two conformationally non-equivalent molecules [(IA and (IB] in the asymmetric unit. In solution, FruAib establishes an equilibrium, with 75.6% of the population consisting of β-pyranose, 10.4% β-furanose, 10.1% α-furanose, 3.0% α-pyranose and <0.7% the acyclic forms. The carbohydrate ring in (I has the normal 2C5 chair conformation and the amino acid portion is in the zwitterion form. Bond lengths and valence angles compare well with the average values from related pyranose structures. All carboxyl, hydroxy and ammonium groups are involved in hydrogen bonding and form a three-dimensional network of infinite chains that are connected through homodromic rings and short chains. Intramolecular hydrogen bonds bridge the amino acid and sugar portions in both molecules. A comparative Hirshfeld surfaces analysis of FruAib and four other sugar–amino acids suggests an increasing role of intramolecular heteroatom interactions in crystal structures with an increasing proportion of C—H bonds.

  7. Small angle neutron scattering

    International Nuclear Information System (INIS)

    Bernardini, G.; Cherubini, G.; Fioravanti, A.; Olivi, A.

    1976-09-01

    A method for the analysis of the data derived from neutron small angle scattering measurements has been accomplished in the case of homogeneous particles, starting from the basic theory without making any assumption on the form of particle size distribution function. The experimental scattering curves are interpreted with the aid the computer by means of a proper routine. The parameters obtained are compared with the corresponding ones derived from observations at the transmission electron microscope

  8. Determination of solid angle

    International Nuclear Information System (INIS)

    Qiu, S.; Amano, H.; Kasai, A.

    1988-01-01

    The solid angle in extended alpha source measurement for a series of counting geometries has been obtained by two methods: (1) calculated by means of the Nelson Blachmen series; (2) interpolated from the data table given by Gardner. A particular consequence of the application of the Nelson Blachmen series was deduced which was different from that given by the original author. The applicability of these two methods, as well as an experimentally measured method, is also evaluated. (author)

  9. The Effects of Word-Learning Biases on Children's Concept of Angle

    Science.gov (United States)

    Gibson, Dominic J.; Congdon, Eliza L.; Levine, Susan C.

    2015-01-01

    Despite evidence that young children are sensitive to differences in angle measure, older students frequently struggle to grasp this important mathematical concept. When making judgments about the size of angles, children often rely on erroneous dimensions such as the length of the angles' sides. The present study tested the possibility that…

  10. BONDING ALUMINUM METALS

    Science.gov (United States)

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  11. Nonperfect synchronization of bond-forming and bond-rupturing processes in the reaction H + H2 → H2 + H

    International Nuclear Information System (INIS)

    Chandra, A.K.; Rao, V.S.

    1996-01-01

    The simplest prototypical hydrogen transfer reaction, i.e., H + H 2 → H 2 + H, is studied by the quantum-mechanical ab initio methods. Results reveal that during this reaction free valence which almost equals the square of the spin density develops on the migrating hydrogen atom. Bond orders are calculated using Mayer's formalism. Both the variations of bond orders and bond lengths along the reaction path are examined. This analysis reveals that the bond formation and bond cleavage processes in this reaction are not perfectly synchronous. The bond clevage process is slightly more advanced on the reaction path. 38 refs., 6 figs., 2 tabs

  12. 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...

  13. Extended fuel cycle length

    International Nuclear Information System (INIS)

    Bruyere, M.; Vallee, A.; Collette, C.

    1986-09-01

    Extended fuel cycle length and burnup are currently offered by Framatome and Fragema in order to satisfy the needs of the utilities in terms of fuel cycle cost and of overall systems cost optimization. We intend to point out the consequences of an increased fuel cycle length and burnup on reactor safety, in order to determine whether the bounding safety analyses presented in the Safety Analysis Report are applicable and to evaluate the effect on plant licensing. This paper presents the results of this examination. The first part indicates the consequences of increased fuel cycle length and burnup on the nuclear data used in the bounding accident analyses. In the second part of this paper, the required safety reanalyses are presented and the impact on the safety margins of different fuel management strategies is examined. In addition, systems modifications which can be required are indicated

  14. Analyzing the installation angle error of a SAW torque sensor

    International Nuclear Information System (INIS)

    Fan, Yanping; Ji, Xiaojun; Cai, Ping

    2014-01-01

    When a torque is applied to a shaft, normal strain oriented at ±45° direction to the shaft axis is at its maximum, which requires two one-port SAW resonators to be bonded to the shaft at ±45° to the shaft axis. In order to make the SAW torque sensitivity high enough, the installation angle error of two SAW resonators must be confined within ±5° according to our design requirement. However, there are few studies devoted to the installation angle analysis of a SAW torque sensor presently and the angle error was usually obtained by a manual method. Hence, we propose an approximation method to analyze the angle error. First, according to the sensitive mechanism of the SAW device to torque, the SAW torque sensitivity is deduced based on the linear piezoelectric constitutive equation and the perturbation theory. Then, when a torque is applied to the tested shaft, the stress condition of two SAW resonators mounted with an angle deviating from ±45° to the shaft axis, is analyzed. The angle error is obtained by means of the torque sensitivities of two orthogonal SAW resonators. Finally, the torque measurement system is constructed and the loading and unloading experiments are performed twice. The torque sensitivities of two SAW resonators are obtained by applying average and least square method to the experimental results. Based on the derived angle error estimation function, the angle error is estimated about 3.447°, which is close to the actual angle error 2.915°. The difference between the estimated angle and the actual angle is discussed. The validity of the proposed angle error analysis method is testified to by the experimental results. (technical design note)

  15. Relativistic distances, sizes, lengths

    International Nuclear Information System (INIS)

    Strel'tsov, V.N.

    1992-01-01

    Such notion as light or retarded distance, field size, formation way, visible size of a body, relativistic or radar length and wave length of light from a moving atom are considered. The relation between these notions is cleared up, their classification is given. It is stressed that the formation way is defined by the field size of a moving particle. In the case of the electromagnetic field, longitudinal sizes increase proportionally γ 2 with growing charge velocity (γ is the Lorentz-factor). 18 refs

  16. Small Angle Neutron Scattering Studies on Blends of Poly (Styrene-ran-Vinyl Phenol) with Liquid Crystalline Polyurethane

    Science.gov (United States)

    Mehta, Rujul

    2005-03-01

    Molecular composites, composed of uniformly dispersed rigid-rod liquid crystalline polymer (LCP) molecules in a flexible amorphous polymer matrix, have remained hitherto elusive due to a scarcity of miscible systems containing a LCP and an amorphous polymer. The production of such a blend, with an experimentally accessible miscibility window, has become possible by modifying the architecture of the flexible polymer, so as to induce favorable intermolecular hydrogen bonding. Specifically, liquid crystalline polyurethanes (LCPU) are found to be miscible with a copolymer of styrene and vinyl phenol; with optimum hydrogen bonding between the carbonyl groups of the urethane linkages and the hydroxyl groups present in the styrenic matrix. Availability of a truly miscible molecular composite presents a unique opportunity of studying the confirmation of polymer chains containing rigid-rods that are uniformly dispersed in a flexible coil matrix. A system consisting of the LCPU and the deuterated styrenic copolymer containing 20% vinyl phenol is examined by Small Angle Neutron Scattering at the National Center for Neutron Research at Gaithersburg and Technology, and the Institute of Solid State Research (IFF) at Jülich. Scattering curves for neat dPS-VPh did not fit the Debye-Bueche model; indicating complex structure. A two correlation length Debye-Bueche model was considered to accommodate for this nonlinear behavior. This model utilizes four fitting parameters, including two correlation lengths a1 and a2, corresponding to a Debye-Bueche model and Guinier model.

  17. Gas phase detection of the NH-P hydrogen bond and importance of secondary interactions

    DEFF Research Database (Denmark)

    Møller, Kristian Holten; Hansen, Anne Schou; Kjærgaard, Henrik Grum

    2015-01-01

    bond compared to secondary interactions. We find that B3LYP favors the hydrogen bond and M06-2X favors the secondary interactions leading to under- and overestimation, respectively, of the hydrogen bond angle relative to a DF-LCCSD(T)-F12a calculated angle. The remaining functionals tested, B3LYP-D3, B......3LYP-D3BJ, CAM-B3LYP, and ωB97X-D, as well as MP2, show comparable contributions from the hydrogen bond and the secondary interactions and are close to DF-LCCSD(T)-F12a results....

  18. The influence of flip angle on the magic angle effect

    International Nuclear Information System (INIS)

    Zurlo, J.V.; Blacksin, M.F.; Karimi, S.

    2000-01-01

    Objective. To assess the impact of flip angle with gradient sequences on the ''magic angle effect''. We characterized the magic angle effect in various gradient echo sequences and compared the signal- to-noise ratios present on these sequences with the signal-to-noise ratios of spin echo sequences.Design. Ten normal healthy volunteers were positioned such that the flexor hallucis longus tendon remained at approximately at 55 to the main magnetic field (the magic angle). The tendon was imaged by a conventional spin echo T1- and T2-weighted techniques and by a series of gradient techniques. Gradient sequences were altered by both TE and flip angle. Signal-to-noise measurements were obtained at segments of the flexor hallucis longus tendon demonstrating the magic angle effect to quantify the artifact. Signal-to-noise measurements were compared and statistical analysis performed. Similar measurements were taken of the anterior tibialis tendon as an internal control.Results and conclusions. We demonstrated the magic angle effect on all the gradient sequences. The intensity of the artifact was affected by both the TE and flip angle. Low TE values and a high flip angle demonstrated the greatest magic angle effect. At TE values less than 30 ms, a high flip angle will markedly increase the magic angle effect. (orig.)

  19. 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...

  20. Corporate Bonds in Denmark

    DEFF Research Database (Denmark)

    Tell, Michael

    2015-01-01

    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...... 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...

  1. Variable angle correlation spectroscopy

    International Nuclear Information System (INIS)

    Lee, Y.K.; Lawrence Berkeley Lab., CA

    1994-05-01

    In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with 13 C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system

  2. The chemical bond as an emergent phenomenon.

    Science.gov (United States)

    Golden, Jon C; Ho, Vinh; Lubchenko, Vassiliy

    2017-05-07

    We first argue that the covalent bond and the various closed-shell interactions can be thought of as symmetry broken versions of one and the same interaction, viz., the multi-center bond. We use specially chosen molecular units to show that the symmetry breaking is controlled by density and electronegativity variation. We show that the bond order changes with bond deformation but in a step-like fashion, regions of near constancy separated by electronic localization transitions. These will often cause displacive transitions as well so that the bond strength, order, and length are established self-consistently. We further argue on the inherent relation of the covalent, closed-shell, and multi-center interactions with ionic and metallic bonding. All of these interactions can be viewed as distinct sectors on a phase diagram with density and electronegativity variation as control variables; the ionic and covalent/secondary sectors are associated with on-site and bond-order charge density wave, respectively, the metallic sector with an electronic fluid. While displaying a contiguity at low densities, the metallic and ionic interactions represent distinct phases separated by discontinuous transitions at sufficiently high densities. Multi-center interactions emerge as a hybrid of the metallic and ionic bond that results from spatial coexistence of delocalized and localized electrons. In the present description, the issue of the stability of a compound is that of the mutual miscibility of electronic fluids with distinct degrees of electron localization, supra-atomic ordering in complex inorganic compounds coming about naturally. The notions of electronic localization advanced hereby suggest a high throughput, automated procedure for screening candidate compounds and structures with regard to stability, without the need for computationally costly geometric optimization.

  3. Redshift or adduct stabilization -- a computational study of hydrogen bonding in adducts of protonated carboxylic acids

    DEFF Research Database (Denmark)

    Olesen, Solveig Gaarn; Hammerum, Steen

    2009-01-01

    It is generally expected that the hydrogen bond strength in a D-H-A adduct is predicted by the difference between the proton affinities of D and A, measured by the adduct stabilization, and demonstrated by the IR redshift of the D-H bond stretching vibrational frequency. These criteria do...... not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The delta-PA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length...... carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength....

  4. Pion nucleus scattering lengths

    International Nuclear Information System (INIS)

    Huang, W.T.; Levinson, C.A.; Banerjee, M.K.

    1971-09-01

    Soft pion theory and the Fubini-Furlan mass dispersion relations have been used to analyze the pion nucleon scattering lengths and obtain a value for the sigma commutator term. With this value and using the same principles, scattering lengths have been predicted for nuclei with mass number ranging from 6 to 23. Agreement with experiment is very good. For those who believe in the Gell-Mann-Levy sigma model, the evaluation of the commutator yields the value 0.26(m/sub σ//m/sub π/) 2 for the sigma nucleon coupling constant. The large dispersive corrections for the isosymmetric case implies that the basic idea behind many of the soft pion calculations, namely, slow variation of matrix elements from the soft pion limit to the physical pion mass, is not correct. 11 refs., 1 fig., 3 tabs

  5. Gap length distributions by PEPR

    International Nuclear Information System (INIS)

    Warszawer, T.N.

    1980-01-01

    Conditions guaranteeing exponential gap length distributions are formulated and discussed. Exponential gap length distributions of bubble chamber tracks first obtained on a CRT device are presented. Distributions of resulting average gap lengths and their velocity dependence are discussed. (orig.)

  6. Relativistic length agony continued

    Directory of Open Access Journals (Sweden)

    Redžić D.V.

    2014-01-01

    Full Text Available We made an attempt to remedy recent confusing treatments of some basic relativistic concepts and results. Following the argument presented in an earlier paper (Redžić 2008b, we discussed the misconceptions that are recurrent points in the literature devoted to teaching relativity such as: there is no change in the object in Special Relativity, illusory character of relativistic length contraction, stresses and strains induced by Lorentz contraction, and related issues. We gave several examples of the traps of everyday language that lurk in Special Relativity. To remove a possible conceptual and terminological muddle, we made a distinction between the relativistic length reduction and relativistic FitzGerald-Lorentz contraction, corresponding to a passive and an active aspect of length contraction, respectively; we pointed out that both aspects have fundamental dynamical contents. As an illustration of our considerations, we discussed briefly the Dewan-Beran-Bell spaceship paradox and the ‘pole in a barn’ paradox. [Projekat Ministarstva nauke Republike Srbije, br. 171028

  7. Spatial structure determination of (√3 x √3)R30 degrees and (1.5 x 1.5)R18 degrees CO on Cu(111) using angle-resolved photoemission extended fine structure

    International Nuclear Information System (INIS)

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A.

    1997-01-01

    The authors report a study of the spatial structure of (√3 x √3)R30 degrees (low coverage) and (1.5 x 1.5)R18 degrees (intermediate coverage) CO adsorbed on Cu(111), using the Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) technique at beamline 9.3.2 at the Advanced Light Source. The CO molecule adsorbs on an atop site for both adsorption phases. Full multiple-scattering spherical-wave (MSSW) calculations were used to extract the C-Cu. bond length and the first Cu-Cu layer spacing for each adsorption phase. The authors find that the C-Cu bond length remains unchanged with increasing coverage, but the 1st Cu-Cu layer spacing contracts at the intermediate coverage. They calculate the bending mode force constant in the (1.5 x 1.5)R18 degrees phase to be K δ = 2.2 (1) x 10 -12 dyne-cm/rad from their experimentally determined bond lengths combined with previously published infra-red absorption frequencies

  8. Spatial structure determination of ({radical}3 x {radical}3)R30{degrees} and (1.5 x 1.5)R18{degrees}CO on Cu(111) using angle-resolved photoemission extended fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors report a study of the spatial structure of ({radical}3 x {radical}3)R30{degrees} (low coverage) and (1.5 x 1.5)R18{degrees} (intermediate coverage) CO adsorbed on Cu(111), using the Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) technique at beamline 9.3.2 at the Advanced Light Source. The CO molecule adsorbs on an atop site for both adsorption phases. Full multiple-scattering spherical-wave (MSSW) calculations were used to extract the C-Cu. bond length and the first Cu-Cu layer spacing for each adsorption phase. The authors find that the C-Cu bond length remains unchanged with increasing coverage, but the 1st Cu-Cu layer spacing contracts at the intermediate coverage. They calculate the bending mode force constant in the (1.5 x 1.5)R18{degrees} phase to be K{sub {delta}} = 2.2 (1) x 10{sup {minus}12} dyne-cm/rad from their experimentally determined bond lengths combined with previously published infra-red absorption frequencies.

  9. Ocular Biometrics of Myopic Eyes With Narrow Angles.

    Science.gov (United States)

    Chong, Gabriel T; Wen, Joanne C; Su, Daniel Hsien-Wen; Stinnett, Sandra; Asrani, Sanjay

    2016-02-01

    The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles. Patients with a stable myopic refraction (myopia worse than -1.00 D spherical equivalent) were prospectively recruited. Angle status was assessed using gonioscopy and biometric measurements were performed using an anterior segment optical coherence tomography and an IOLMaster. A total of 29 patients (58 eyes) were enrolled with 13 patients (26 eyes) classified as having narrow angles and 16 patients (32 eyes) classified as having open angles. Baseline demographics of age, sex, and ethnicity did not differ significantly between the 2 groups. The patients with narrow angles were on average older than those with open angles but the difference did not reach statistical significance (P=0.12). The central anterior chamber depth was significantly less in the eyes with narrow angles (P=0.05). However, the average lens thickness, although greater in the eyes with narrow angles, did not reach statistical significance (P=0.10). Refractive error, axial lengths, and iris thicknesses did not differ significantly between the 2 groups (P=0.32, 0.47, 0.15). Narrow angles can occur in myopic eyes. Routine gonioscopy is therefore recommended for all patients regardless of refractive error.

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

    Science.gov (United States)

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

    2014-04-01

    It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation. © 2013 Elsevier B.V. All rights reserved.

  11. Unusual bonding and properties in main group element chemistry: rational synthesis, characterization, and experimental electron density determination of mixed-valent tetraphosphetes.

    Science.gov (United States)

    Breuers, Verena; Lehmann, Christian W; Frank, Walter

    2015-03-16

    Five dispirocyclic λ(3),λ(5)-tetraphosphetes [{R2Si(NR(1))(NR(2))P2}2] (R(1) = R(2) and R(1) ≠ R(2)) are easily prepared in almost quantitative yields via photolysis of the respective bis(trimethylsilyl)phosphanyldiazaphosphasiletidines with intense visible light. These deep-yellow low-coordinate phosphorus compounds can be considered as the first higher congeners of the well-known cyclodiphosphazenes. The tetraphosphetes are remarkably stable in air and show unexpected molecular properties related to the unique bonding situation of the central four-π-electron four-membered phosphorus ring. The extent of rhombic distortion of the central P4 ring is remarkable due to an unusually acute angle at the σ(2)-phosphorus atoms. All of the P-P bonds are approximately equal in length. The distances are in the middle of the range given by phosphorus single and double bonds. The anisotropic absorption of visible light that can easily be observed in the case of the yellow/colorless dichroic crystals of [{Me2Si(NtBu)(NtBu)P2}2] and the exceptional (31)P NMR chemical shift of the σ(2)-phosphorus atoms are the most remarkable features of the λ(3),λ(5)-tetraphosphetes. In the case of [{Me2Si(NtBu)(NtBu)P2}2], the Hansen-Coppens multipole model is applied to extract the electron density from high-resolution X-ray diffraction data obtained at 100 K. Static deformation density and topological analysis reveal a unique bonding situation in the central unsaturated P4 fragment characterized by polar σ-bonding, pronounced out-of-ring non-bonding lone pair density on the σ(2)-phosphorus atoms, and an additional non-classical three-center back-bonding contribution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. ASSESSMENT OF LENS THICKNESS IN ANGLE CLOSURE DISEASE

    Directory of Open Access Journals (Sweden)

    Nishat Sultana Khayoom

    2016-08-01

    Full Text Available BACKGROUND Anterior chamber depth and lens thickness have been considered as important biometric determinants in primary angle-closure glaucoma. Patients with primary narrow angle may be classified as a primary angle closure suspect (PACS, or as having primary angle closure (PAC or primary angle closure glaucoma (PACG. 23.9% of patients with primary angle closure disease are in India, which highlights the importance of understanding the disease, its natural history, and its underlying pathophysiology, so that we may try to establish effective methods of treatment and preventative measures to delay, or even arrest, disease progression, thereby reducing visual morbidity. AIM To determine the lens thickness using A-scan biometry and its significance in various stages of angle closure disease. MATERIALS AND METHODS Patients attending outpatient department at Minto Ophthalmic Hospital between October 2013 to May 2015 were screened for angle closure disease and subsequently evaluated at glaucoma department. In our study, lens thickness showed a direct correlation with shallowing of the anterior chamber by determining the LT/ ACD ratio. A decrease in anterior chamber depth is proportional to the narrowing of the angle which contributes to the progression of the angle closure disease from just apposition to occlusion enhancing the risk for optic nerve damage and visual field loss. Hence, if the lens thickness values are assessed earlier in the disease process, appropriate intervention can be planned. CONCLUSION Determination of lens changes along with anterior chamber depth and axial length morphometrically can aid in early detection of angle closure. The role of lens extraction for PACG is a subject of increased interest. Lens extraction promotes the benefits of anatomical opening of the angle, IOP reduction and improved vision. This potential intervention may be one among the armamentarium of approaches for PACG. Among the current treatment modalities

  13. Odd Length Contraction

    Science.gov (United States)

    Smarandache, Florentin

    2013-09-01

    Let's denote by VE the speed of the Earth and byVR the speed of the rocket. Both travel in the same direction on parallel trajectories. We consider the Earth as a moving (at a constant speed VE -VR) spacecraft of almost spherical form, whose radius is r and thus the diameter 2r, and the rocket as standing still. The non-proper length of Earth's diameter, as measured by the astronaut is: L = 2 r√{ 1 -|/VE -VR|2 c2 } rocket! Also, let's assume that the astronaut is laying down in the direction of motion. Therefore, he would also shrink, or he would die!

  14. discouraged by queue length

    Directory of Open Access Journals (Sweden)

    P. R. Parthasarathy

    2001-01-01

    Full Text Available The transient solution is obtained analytically using continued fractions for a state-dependent birth-death queue in which potential customers are discouraged by the queue length. This queueing system is then compared with the well-known infinite server queueing system which has the same steady state solution as the model under consideration, whereas their transient solutions are different. A natural measure of speed of convergence of the mean number in the system to its stationarity is also computed.

  15. Bond markets in Africa

    Directory of Open Access Journals (Sweden)

    Yibin Mu

    2013-07-01

    Full Text Available African bond markets have been steadily growing in recent years, but nonetheless remain undeveloped. African countries would benefit from greater access to financing and deeper financial markets. This paper compiles a unique set of data on government securities and corporate bond markets in Africa. It then applies an econometric model to analyze the key determinants of African government securities market and corporate bond market capitalization. Government securities market capitalization is directly related to better institutions and interest rate volatility, and inversely related to smaller fiscal deficits, higher interest rate spreads, exchange rate volatility, and current and capital account openness. Corporate bond market capitalization is directly linked to economic size, the level of development of the economy and financial markets, better institutions, and interest rate volatility, and inversely related to higher interest rate spreads and current account openness. Policy implications follow.

  16. EXPERIMENTAL INVESTIGATION ON THE EFFECT OF NATURAL TROPICAL WEATHER ON INTERFACIAL BONDING PERFORMANCE OF CFRP-CONCRETE BONDING SYSTEM

    Directory of Open Access Journals (Sweden)

    MOHD H. MOHD HASHIM

    2016-04-01

    Full Text Available The existing reinforced concrete structures may require rehabilitation and strengthening to overcome deficiencies due to defect and environmental deterioration. Fibre Reinforced Polymer (FRP-concrete bonding systems can provide solution for the deficiencies, but the durability of the bonded joint needs to be investigated for reliable structural performance. In this research the interfacial bonding behaviour of CFRP-concrete system under tropical climate exposure is main interest. A 300 mm concrete prism was bonded with CFRP plate on its two sides and exposed for 3, 6, and 9 months to laboratory environment, continuous natural weather, and wet-dry exposure in 3.5% saltwater solution at room and 40 °C temperature. The prisms were subjected to tension and compression load under bonding test to measure the strain and determine stress distribution and shear stress transfer behaviour. The results of the bonding test showed that load transfer was fairly linear and uniform at lower load level and changed to non-linear and non- uniform at higher load level. The force transfers causes the shear stress distribution being shifted along the bonded length. The combination of climate effects may have provided better curing of the bonded joints, but longer duration of exposure may be required to weaken the bond strength. Nevertheless, CFRP-concrete bonding system was only minimally affected under the tropical climate and salt solution.

  17. 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.

  18. Diffusion bonding techniques

    International Nuclear Information System (INIS)

    Peters, R.D.

    1978-01-01

    The applications of diffusion bonding at the General Electric Neutron Devices Department are briefly discussed, with particular emphasis on the gold/gold or gold/indium joints made between metallized alumina ceramic parts in the vacuum switch tube and the crystal resonator programs. Fixtures which use the differential expansion of dissimilar metals are described and compared to one that uses hydraulic pressure to apply the necessary bonding force

  19. Fusion bonding of Si wafers investigated by x ray diffraction

    DEFF Research Database (Denmark)

    Weichel, Steen; Grey, Francois; Rasmussen, Kurt

    2000-01-01

    The interface structure of bonded Si(001) wafers with twist angle 6.5 degrees is studied as a function of annealing temperature. An ordered structure is observed in x-ray diffraction by monitoring a satellite reflection due to the periodic modulation near the interface, which results from...

  20. The double Brewster angle effect

    Science.gov (United States)

    Thirion-Lefevre, Laetitia; Guinvarc'h, Régis

    2018-01-01

    The Double Brewster angle effect (DBE) is an extension of the Brewster angle to double reflection on two orthogonal dielectric surfaces. It results from the combination of two pseudo-Brewster angles occurring in complementary incidence angles domains. It can be observed for a large range of incidence angles provided that double bounces mechanism is present. As a consequence of this effect, we show that the reflection coefficient at VV polarization can be at least 10 dB lower than the reflection coefficient at HH polarization over a wide range of incidence angle - typically from 20 to 70∘. It is experimentally demonstrated using a Synthetic Aperture Radar (SAR) image that this effect can be seen on buildings and forests. For large buildings, the difference can reach more than 20 dB. xml:lang="fr"

  1. A national facility for small angle neutron scattering

    International Nuclear Information System (INIS)

    Buyers, W.J.L.; Katsaras, J.; Mellors, W.; Potter, M.M.; Powell, B.M.; Rogge, R.B.; Root, J.H.; Tennant, D.C.; Tun, Z.

    1995-01-01

    A world-class small angle neutron scattering (SANS) facility is proposed for Canada. It will provide users from the fields of biology, chemistry, physics, materials science and engineering with a uniquely powerful tool for investigating microstructural properties whose length scales lie in the optical to atomic range. (author). 7 refs

  2. A national facility for small angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Buyers, W J.L.; Katsaras, J; Mellors, W; Potter, M M; Powell, B M; Rogge, R B; Root, J H; Tennant, D C; Tun, Z [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Epand, R; Gaulin, B D [McMaster Univ., Hamilton, ON (Canada)

    1995-09-15

    A world-class small angle neutron scattering (SANS) facility is proposed for Canada. It will provide users from the fields of biology, chemistry, physics, materials science and engineering with a uniquely powerful tool for investigating microstructural properties whose length scales lie in the optical to atomic range. (author). 7 refs.

  3. Angle Performance on Optima XE

    International Nuclear Information System (INIS)

    David, Jonathan; Satoh, Shu

    2011-01-01

    Angle control on high energy implanters is important due to shrinking device dimensions, and sensitivity to channeling at high beam energies. On Optima XE, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through a series of narrow slits, and any angle adjustment is made by steering the beam with the corrector magnet. In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen during implant.Using a sensitive channeling condition, we were able to quantify the angle repeatability of Optima XE. By quantifying the sheet resistance sensitivity to both horizontal and vertical angle variation, the total angle variation was calculated as 0.04 deg. (1σ). Implants were run over a five week period, with all of the wafers selected from a single boule, in order to control for any crystal cut variation.

  4. Control of chemical bonding of the ZnO surface grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Ogata, K.; Komuro, T.; Hama, K.; Koike, K.; Sasa, S.; Inoue, M.; Yano, M.

    2004-01-01

    Toward the fabrication of enzyme modified field effect transistors (EnFETs) as one of organic/inorganic hybridized structures, surface bonding of the ZnO grown by molecular beam epitaxy was controlled by ex situ treatments. Angle resolved X-ray photoelectron spectroscopy (XPS) measurement revealed that O-H bonds exist at the surface of ZnO. It was found that the number of O-H bond could be changed with reversibility using plasma and thermal treatments

  5. The Valency Theory: The Human Bond From A New Psychoanalytic Perspective

    OpenAIRE

    Med Hafsi

    2008-01-01

    The present paper discusses some psychoanalytical conceptions concerning what links people to each other, or the human bond. Psychoanalysis, can be regarded as a science dealing basically with, although not directly, the human bond or link linking the person with his external and internal objects. The fact that this bond is in perpetualtransformation, and therefore can be apprehended from different angles has led to various psychoanalytical conceptions or theories which are more complementary...

  6. Small angle neutron scattering

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice

    2015-01-01

    Full Text Available Small Angle Neutron Scattering (SANS is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ∼ 1 nm up to ∼ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ∼ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area… through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer, form factor analysis (I(q→0, Guinier regime, intermediate regime, Porod regime, polydisperse system, structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates, and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast. It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of

  7. The Influence of Disorder in Multifilament Yarns on the Bond Performance in Textile Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    M. Konrad

    2004-01-01

    Full Text Available In this paper we analyze the performance of a bond layer between the multi-filament yarn and the cementitious matrix. The performance of the bond layer is a central issue in the development of textile-reinforced concrete. The changes in the microstructure during the loading result in distinguished failure mechanisms on the micro, meso and macro scales. The paper provides a brief review of these effects and describes a modeling strategy capable of reflecting the failure process. Using the model of the bond layer we illuminate the correspondence between the disorder in the microstructure of the yarn and the bonding behavior at the meso- and macro level. Particular interest is paid to the influence of irregularities in the micro-structure (relative differences in filament lengths, varying bond quality, bond-free length for different levels of local bond quality between the filament surface and the matrix. 

  8. Topological Qubits from Valence Bond Solids

    Science.gov (United States)

    Wang, Dong-Sheng; Affleck, Ian; Raussendorf, Robert

    2018-05-01

    Topological qubits based on S U (N )-symmetric valence-bond solid models are constructed. A logical topological qubit is the ground subspace with twofold degeneracy, which is due to the spontaneous breaking of a global parity symmetry. A logical Z rotation by an angle 2 π /N , for any integer N >2 , is provided by a global twist operation, which is of a topological nature and protected by the energy gap. A general concatenation scheme with standard quantum error-correction codes is also proposed, which can lead to better codes. Generic error-correction properties of symmetry-protected topological order are also demonstrated.

  9. 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.

  10. Interstellar hydrogen bonding

    Science.gov (United States)

    Etim, Emmanuel E.; Gorai, Prasanta; Das, Ankan; Chakrabarti, Sandip K.; Arunan, Elangannan

    2018-06-01

    This paper reports the first extensive study of the existence and effects of interstellar hydrogen bonding. The reactions that occur on the surface of the interstellar dust grains are the dominant processes by which interstellar molecules are formed. Water molecules constitute about 70% of the interstellar ice. These water molecules serve as the platform for hydrogen bonding. High level quantum chemical simulations for the hydrogen bond interaction between 20 interstellar molecules (known and possible) and water are carried out using different ab-intio methods. It is evident that if the formation of these species is mainly governed by the ice phase reactions, there is a direct correlation between the binding energies of these complexes and the gas phase abundances of these interstellar molecules. Interstellar hydrogen bonding may cause lower gas abundance of the complex organic molecules (COMs) at the low temperature. From these results, ketenes whose less stable isomers that are more strongly bonded to the surface of the interstellar dust grains have been observed are proposed as suitable candidates for astronomical observations.

  11. Coherent Smith-Purcell radiation as a diagnostic for sub-picosecond electron bunch length

    International Nuclear Information System (INIS)

    Nguyen, D.C.

    1996-01-01

    We suggest a novel technique of measuring sub-picosecond electron bunch length base on coherent Smith-Purcell radiation (SPR) emitted when electrons pass close to the surface of a metal grating. With electron bunch lengths comparable to the grating period, we predict that coherent SPR will be emitted at large angles with respect to direction of beam propagation. As the bunch length shortens, the coherent SPR will be enhanced over the incoherent component that is normally observed at small angles. Furthermore, the angular distribution of the coherent SPR will be shifted toward smaller angles as the bunch length becomes much smaller than the grating period. By measuring the angular distribution of the coherent SPR, one can determine the bunch length of sub-picosecond electron pulses. This new technique is easy to implement and appears capable of measuring femtosecond electron bunch lengths

  12. Safe and Liquid Mortgage Bonds

    DEFF Research Database (Denmark)

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

    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...... 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...

  13. Alkyl Radicals as Hydrogen Bond Acceptors: Computational Evidence

    DEFF Research Database (Denmark)

    Hammerum, Steen

    2009-01-01

    Spectroscopic, energetic and structural information obtained by DFT and G3-type computational studies demonstrates that charged proton donors can form moderately strong hydrogen bonds to simple alkyl radicals. The presence of these bonds stabilizes the adducts and modifies their structure......, and gives rise to pronounced shifts of IR stretching frequencies and to increased absorption intensities. The hydrogen bond acceptor properties of alkyl radicals equal those of many conventional acceptors, e.g., the bond length changes and IR red-shifts suggest that tert-butyl radicals are slightly better...... acceptors than formaldehyde molecules, while propyl radicals are as good as H2O. The hydrogen bond strength appears to depend on the proton affinity of the proton donor and on the ionization energy of the acceptor alkyl radical, not on the donor-acceptor proton affinity difference, reflecting...

  14. Automated analysis of angle closure from anterior chamber angle images.

    Science.gov (United States)

    Baskaran, Mani; Cheng, Jun; Perera, Shamira A; Tun, Tin A; Liu, Jiang; Aung, Tin

    2014-10-21

    To evaluate a novel software capable of automatically grading angle closure on EyeCam angle images in comparison with manual grading of images, with gonioscopy as the reference standard. In this hospital-based, prospective study, subjects underwent gonioscopy by a single observer, and EyeCam imaging by a different operator. The anterior chamber angle in a quadrant was classified as closed if the posterior trabecular meshwork could not be seen. An eye was classified as having angle closure if there were two or more quadrants of closure. Automated grading of the angle images was performed using customized software. Agreement between the methods was ascertained by κ statistic and comparison of area under receiver operating characteristic curves (AUC). One hundred forty subjects (140 eyes) were included, most of whom were Chinese (102/140, 72.9%) and women (72/140, 51.5%). Angle closure was detected in 61 eyes (43.6%) with gonioscopy in comparison with 59 eyes (42.1%, P = 0.73) using manual grading, and 67 eyes (47.9%, P = 0.24) with automated grading of EyeCam images. The agreement for angle closure diagnosis between gonioscopy and both manual (κ = 0.88; 95% confidence interval [CI), 0.81-0.96) and automated grading of EyeCam images was good (κ = 0.74; 95% CI, 0.63-0.85). The AUC for detecting eyes with gonioscopic angle closure was comparable for manual and automated grading (AUC 0.974 vs. 0.954, P = 0.31) of EyeCam images. Customized software for automated grading of EyeCam angle images was found to have good agreement with gonioscopy. Human observation of the EyeCam images may still be needed to avoid gross misclassification, especially in eyes with extensive angle closure. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  15. A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

    Directory of Open Access Journals (Sweden)

    Jarosław Poznański

    Full Text Available Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

  16. A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

    Science.gov (United States)

    Poznański, Jarosław; Poznańska, Anna; Shugar, David

    2014-01-01

    Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

  17. Cement bond evaluation method in horizontal wells using segmented bond tool

    Science.gov (United States)

    Song, Ruolong; He, Li

    2018-06-01

    Most of the existing cement evaluation technologies suffer from tool eccentralization due to gravity in highly deviated wells and horizontal wells. This paper proposes a correction method to lessen the effects of tool eccentralization on evaluation results of cement bond using segmented bond tool, which has an omnidirectional sonic transmitter and eight segmented receivers evenly arranged around the tool 2 ft from the transmitter. Using 3-D finite difference parallel numerical simulation method, we investigate the logging responses of centred and eccentred segmented bond tool in a variety of bond conditions. From the numerical results, we find that the tool eccentricity and channel azimuth can be estimated from measured sector amplitude. The average of the sector amplitude when the tool is eccentred can be corrected to the one when the tool is centred. Then the corrected amplitude will be used to calculate the channel size. The proposed method is applied to both synthetic and field data. For synthetic data, it turns out that this method can estimate the tool eccentricity with small error and the bond map is improved after correction. For field data, the tool eccentricity has a good agreement with the measured well deviation angle. Though this method still suffers from the low accuracy of calculating channel azimuth, the credibility of corrected bond map is improved especially in horizontal wells. It gives us a choice to evaluate the bond condition for horizontal wells using existing logging tool. The numerical results in this paper can provide aids for understanding measurements of segmented tool in both vertical and horizontal wells.

  18. Measurement of the angle gamma

    International Nuclear Information System (INIS)

    Aleksan, R.; Sphicas, P.; Massachusetts Inst. of Tech., Cambridge, MA

    1993-12-01

    The angle γ as defined in the Wolfenstein approximation is not completely out of reach of current or proposed dedicated B experiments. This work represents but a first step in the direction of extracting the third angle of the unitarity triangle by study the feasibility of using new decay modes in a hadronic machine. (A.B.). 11 refs., 1 fig., 7 tabs

  19. Nucleation of small angle boundaries

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1996-12-01

    Full Text Available The internal stresses induced by the strain gradients in an array of lattice cells delineated by low-angle dislocation boundaries are partially relieved by the creation of new low-angle boundaries. This is shown to be a first-order transition...

  20. 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

  1. Continuing bonds and place.

    Science.gov (United States)

    Jonsson, Annika; Walter, Tony

    2017-08-01

    Where do people feel closest to those they have lost? This article explores how continuing bonds with a deceased person can be rooted in a particular place or places. Some conceptual resources are sketched, namely continuing bonds, place attachment, ancestral places, home, reminder theory, and loss of place. The authors use these concepts to analyze interview material with seven Swedes and five Britons who often thought warmly of the deceased as residing in a particular place and often performing characteristic actions. The destruction of such a place, by contrast, could create a troubling, haunting absence, complicating the deceased's absent-presence.

  2. A Study of Radiation Incidence Angle in Anteroposterior Cervical Vertebra Examination

    International Nuclear Information System (INIS)

    Jeung, Seung Woon; Lim, Cheong Hwan; Jung, Hong Ryang; Joo, Yeong Cheol; Park, Mi Ja; Han, Beon Hee

    2012-01-01

    In anteroposterior projection for cervical vertebra, it is general that the incidence angle of X-ray is 15 degrees to 20 degrees to head in order to prevent overlap of mandible and occipital bone and to observe array of cervical interbody and shapes of joints. However, the angle is appropriate for foreigners that was determined by foreign literature review long ago, and there have been few researches of incidence angle for Koreans' body type. The purpose of in this study are to identify the incidence angle appropriate for Koreans and to present methodology. In order to measure the incidence angle, 1,044 patients who visited S Hospital located in Seosan were selected and measured of average length of cervical vertebra, OID, axis angle, and FID. The incidence angle was calculated from the applied formula by measuring average values per age groups and sex (see Formula 1 and 2). The average length of cervical vertebra was 6cm: the length was increased from teenagers to twenties but was decreased since thirties. The difference between males and females was around 1cm (p<.01). The OID was almost the same regardless of age groups and sex. As for axis angle, the slope was increased in teenagers and twenties, but was decreased since thirties. The difference between males and females was around 2 degrees (p<.01). The FID measurements were almost the same regardless of age groups and sex, and when the incidence angle was measured from these values, the teenagers were 15.9 degrees, the twenties were 16.9 degrees, the thirties were 16.6 degrees, the forties were 16.2 degrees, the fifties were 15.9 degrees, and the sixties were 14.5 degrees, indicating that the angle was increased from teenagers to the twenties but decreased since the thirties. While the angles of males and females were measured to be the same in the teenagers, the angle was different between males and females by 2 degrees. When the incidence angle statistically analyzed with measurement of average length of

  3. A Study of Radiation Incidence Angle in Anteroposterior Cervical Vertebra Examination

    Energy Technology Data Exchange (ETDEWEB)

    Jeung, Seung Woon; Lim, Cheong Hwan; Jung, Hong Ryang; Joo, Yeong Cheol; Park, Mi Ja [Dept. of Radiological Science, Hanseo University, Seosan (Korea, Republic of); Han, Beon Hee [Dept. of Radiological Science, Seonam University, Namwon (Korea, Republic of)

    2012-06-15

    In anteroposterior projection for cervical vertebra, it is general that the incidence angle of X-ray is 15 degrees to 20 degrees to head in order to prevent overlap of mandible and occipital bone and to observe array of cervical interbody and shapes of joints. However, the angle is appropriate for foreigners that was determined by foreign literature review long ago, and there have been few researches of incidence angle for Koreans' body type. The purpose of in this study are to identify the incidence angle appropriate for Koreans and to present methodology. In order to measure the incidence angle, 1,044 patients who visited S Hospital located in Seosan were selected and measured of average length of cervical vertebra, OID, axis angle, and FID. The incidence angle was calculated from the applied formula by measuring average values per age groups and sex (see Formula 1 and 2). The average length of cervical vertebra was 6cm: the length was increased from teenagers to twenties but was decreased since thirties. The difference between males and females was around 1cm (p<.01). The OID was almost the same regardless of age groups and sex. As for axis angle, the slope was increased in teenagers and twenties, but was decreased since thirties. The difference between males and females was around 2 degrees (p<.01). The FID measurements were almost the same regardless of age groups and sex, and when the incidence angle was measured from these values, the teenagers were 15.9 degrees, the twenties were 16.9 degrees, the thirties were 16.6 degrees, the forties were 16.2 degrees, the fifties were 15.9 degrees, and the sixties were 14.5 degrees, indicating that the angle was increased from teenagers to the twenties but decreased since the thirties. While the angles of males and females were measured to be the same in the teenagers, the angle was different between males and females by 2 degrees. When the incidence angle statistically analyzed with measurement of average length

  4. Short Carboxylic Acid–Carboxylate Hydrogen Bonds Can Have Fully Localized Protons

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jiusheng; Pozharski, Edwin; Wilson, Mark A.

    2017-01-17

    Short hydrogen bonds (H-bonds) have been proposed to play key functional roles in several proteins. The location of the proton in short H-bonds is of central importance, as proton delocalization is a defining feature of low-barrier hydrogen bonds (LBHBs). Experimentally determining proton location in H-bonds is challenging. Here, bond length analysis of atomic (1.15–0.98 Å) resolution X-ray crystal structures of the human protein DJ-1 and its bacterial homologue, YajL, was used to determine the protonation states of H-bonded carboxylic acids. DJ-1 contains a buried, dimer-spanning 2.49 Å H-bond between Glu15 and Asp24 that satisfies standard donor–acceptor distance criteria for a LBHB. Bond length analysis indicates that the proton is localized on Asp24, excluding a LBHB at this location. However, similar analysis of the Escherichia coli homologue YajL shows both residues may be protonated at the H-bonded oxygen atoms, potentially consistent with a LBHB. A Protein Data Bank-wide screen identifies candidate carboxylic acid H-bonds in approximately 14% of proteins, which are typically short [O–O> = 2.542(2) Å]. Chemically similar H-bonds between hydroxylated residues (Ser/Thr/Tyr) and carboxylates show a trend of lengthening O–O distance with increasing H-bond donor pKa. This trend suggests that conventional electronic effects provide an adequate explanation for short, charge-assisted carboxylic acid–carboxylate H-bonds in proteins, without the need to invoke LBHBs in general. This study demonstrates that bond length analysis of atomic resolution X-ray crystal structures provides a useful experimental test of certain candidate LBHBs.

  5. Evaluation of enamel damages following orthodontic bracket debonding in fluorosed teeth bonded with adhesion promoter.

    Science.gov (United States)

    Baherimoghadam, Tahreh; Akbarian, Sahar; Rasouli, Reza; Naseri, Navid

    2016-01-01

    To evaluate shear bond strength (SBS) of the orthodontic brackets bonded to fluorosed and nonfluorosed teeth using Light Bond with and without adhesion promoters and compare their enamel damages following debonding. In this study, 30 fluorosed (Thylstrup and Fejerskov Index = 4-5) and 30 nonfluorosed teeth were randomly distributed between two subgroups according to the bonding materials: Group 1, fluorosed teeth bonded with Light Bond; Group 2, fluorosed teeth bonded with adhesion promoters and Light Bond; Group 3, nonfluorosed teeth bonded with Light Bond; Group 4, nonfluorosed bonded with adhesion promoters and Light Bond. After bonding, the SBS of the brackets was tested with a universal testing machine. Stereomicroscopic evaluation was performed by unbiased stereology in all teeth to determine the amount of adhesive remnants and the number and length of enamel cracks before bonding and after debonding. The data were analyzed using two-way analysis of variance, Kruskal-Wallis, Wilcoxon Signed Rank, and Mann-Whitney test. While fluorosis reduced the SBS of orthodontic bracket (P = 0.017), Enhance Locus Ceruleus LC significantly increased the SBS of the orthodontic bracket in fluorosed and nonfluorosed teeth (P = 0.039). Significant increasing in the number and length of enamel crack after debonding was found in all four groups. There were no significant differences in the length of enamel crack increased after debonding among four groups (P = 0.768) while increasing in the number of enamel cracks after debonding was significantly different among the four groups (P = 0.023). Teeth in Group 2 showed the highest enamel damages among four groups following debonding. Adhesion promoters could improve the bond strength of orthodontic brackets, but conservative debonding methods for decreasing enamel damages would be necessary.

  6. Identification of the formation of metal-vinylidene interfacial bonds of alkyne-capped platinum nanoparticles by isotopic labeling.

    Science.gov (United States)

    Hu, Peiguang; Chen, Limei; Deming, Christopher P; Bonny, Lewis W; Lee, Hsiau-Wei; Chen, Shaowei

    2016-10-07

    Stable platinum nanoparticles were prepared by the self-assembly of 1-dodecyne and dodec-1-deuteroyne onto bare platinum colloid surfaces. The nanoparticles exhibited consistent core size and optical properties. FTIR and NMR measurements confirmed the formation of Pt-vinylidene (Pt[double bond, length as m-dash]C[double bond, length as m-dash]CH-) interfacial linkages rather than Pt-acetylide (Pt-C[triple bond, length as m-dash]C-) and platinum-hydride (Pt-H) bonds.

  7. Similarities between intra- and intermolecular hydrogen bonds in RNA kissing complexes found by means of cross-correlated relaxation

    International Nuclear Information System (INIS)

    Dittmer, Jens; Kim, Chul-Hyun; Bodenhausen, Geoffrey

    2003-01-01

    The bond lengths and dynamics of intra- and intermolecular hydrogen bonds in an RNA kissing complex have been characterized by determining the NMR relaxation rates of various double- and triple-quantum coherences that involve an imino proton and two neighboring nitrogen-15 nuclei belonging to opposite bases. New experiments allow one to determine the chemical shift anisotropy of the imino protons. The bond lengths derived from dipolar relaxation and the lack of modulations of the nitrogen chemical shifts indicate that the intermolecular hydrogen bonds which hold the kissing complex together are very similar to the intramolecular hydrogen bonds in the double-stranded stem of the RNA

  8. A new hydrocarbon empirical potential in angle bending calculation for the molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ping, Tan Ai; Hoe, Yeak Su [Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Johor Darul Takzim (Malaysia)

    2014-07-10

    Typically, short range potential only depends on neighbouring atoms and its parameters function can be categorized into bond stretching, angle bending and bond rotation potential. In this paper, we present our work called Angle Bending (AB) potential, whereas AB potential is the extension of our previous work namely Bond Stretching (BS) potential. Basically, potential will tend to zero after truncated region, potential in specific region can be represented by different piecewise polynomial. We proposed the AB piecewise potential which is possible to solve a system involving three atoms. AB potential able to handle the potential of covalent bonds for three atoms as well as two atoms cases due to its degeneracy properties. Continuity for the piecewise polynomial has been enforced by coupling with penalty methods. There are still plenty of improvement spaces for this AB potential. The improvement for three atoms AB potential will be studied and further modified into torsional potential which are the ongoing current research.

  9. Relationship between the Angle of Repose and Angle of Internal ...

    African Journals Online (AJOL)

    ). The angle of internal friction ... compression chambers. Lorenzen, 1957 (quoted by Mohsenin,. 1986), reported that the design of deep ... tiongiven for lateral pressure in deep bins as presented by Mohsenin. (1986). The presence of moisture ...

  10. 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-EMU memb......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...

  11. Ring magnet firing angle control

    International Nuclear Information System (INIS)

    Knott, M.J.; Lewis, L.G.; Rabe, H.H.

    1975-01-01

    A device is provided for controlling the firing angles of thyratrons (rectifiers) in a ring magnet power supply. A phase lock loop develops a smooth ac signal of frequency equal to and in phase with the frequency of the voltage wave developed by the main generator of the power supply. A counter that counts from zero to a particular number each cycle of the main generator voltage wave is synchronized with the smooth AC signal of the phase lock loop. Gates compare the number in the counter with predetermined desired firing angles for each thyratron and with coincidence the proper thyratron is fired at the predetermined firing angle

  12. Amalgam shear bond strength to dentin using different bonding agents.

    Science.gov (United States)

    Vargas, M A; Denehy, G E; Ratananakin, T

    1994-01-01

    This study evaluated the shear bond strength of amalgam to dentin using five different bonding agents: Amalgambond Plus, Optibond, Imperva Dual, All-Bond 2, and Clearfil Liner Bond. Flat dentin surfaces obtained by grinding the occlusal portion of 50 human third molars were used for this study. To contain the amalgam on the tooth surface, cylindrical plastic molds were placed on the dentin and secured with sticky wax. The bonding agents were then applied according to the manufacturers' instructions or light activated and Tytin amalgam was condensed into the plastic molds. The samples were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. Analysis by one-way ANOVA indicated significant difference between the five groups (P < 0.05). The bond strength of amalgam to dentin was significantly higher with Amalgambond Plus using the High-Performance Additive than with the other four bonding agents.

  13. The Effect of Glancing Angle Deposition Conditions on the Morphology of a Silver Nanohelix Array

    Directory of Open Access Journals (Sweden)

    Yi-Jun Jen

    2017-09-01

    Full Text Available Silver nanohelices were grown on smooth substrates using glancing angle deposition and substrate cooling. Various nanohelix arrays were deposited under different deposition conditions—different deposition rates, substrate spin rates, deposition angles, and substrate temperatures. The effect of deposition conditions on the morphology of each nanohelix array in terms of pitch angle, pitch length, wire diameter, and radius of curvature was investigated. The dependence of circular dichroism on the size of the nanohelix arrays was also measured and demonstrated.

  14. The influence of adherent surface preparation on bond durability

    International Nuclear Information System (INIS)

    Rider, A.N.; Arnott, D.R.; Olsson-Jacques, C.L.

    1999-01-01

    Full text: One of the major factors limiting the use of adhesive bonding is the problem associated with the production of adhesive joints that can maintain their initial strength over long periods of time in hostile environments. It is well known that the adherent surface preparation method is critical to the formation of a durable adhesive bond. Work presented in this paper focuses on the critical aspects of the surface preparation of aluminium employed for the manufacture of aluminium-epoxy joints. The surface preparation procedure examined is currently employed by the RAAF for repairs requiring metal to adhesive bonding. The influence of each step in the surface preparation on the ultimate bond durability performance of the adhesive joint is examined by a combination of methods. Double cantilever wedge style adhesive joints are loaded in mode 1 opening and then exposed to a humid environment. X-ray photoelectron spectroscopy (XPS) and contact angle measurements of the aluminium adherent before bonding provides information about the adherent surface chemistry. XPS is also employed to analyse the surfaces of the bonded specimens post failure to establish the locus of fracture. This approach provides important information regarding the properties influencing bond durability as well as the bond failure mechanisms. A two step bond degradation model was developed to qualitatively describe the observed bond durability performance and fracture data. The first step involves controlled moisture ingress by stress induced microporosity of the adhesive in the interfacial region. The second step determines the locus of fracture through the relative dominance of one of three competitive processes, viz: oxide degradation, polymer desorption, or polymer degradation. A key element of the model is the control exercised over the interfacial microporosity by the combined interaction of stress and the relative densities of strong and weak linkages at the metal to adhesive interface

  15. Convertible bond valuation focusing on Chinese convertible bond market

    OpenAIRE

    Yang, Ke

    2010-01-01

    This paper mainly discusses the methods of valuation of convertible bonds in Chinese market. Different from common convertible bonds in European market, considering the complicate features of Chinese convertible bond, this paper represents specific pricing approaches for pricing convertible bonds with different provisions along with the increment of complexity of these provisions. More specifically, this paper represents the decomposing method and binomial tree method for pricing both of Non-...

  16. Oblique-Length Contraction Factor in the Special Theory of Relativity

    Directory of Open Access Journals (Sweden)

    Smarandache F.

    2013-01-01

    Full Text Available In this paper one generalizes the Lorentz Contraction Factor for the case when the lengths are moving at an oblique angle with respect to the motion direction. One shows that the angles of the moving relativistic objects are distorted.

  17. Amide proton temperature coefficients as hydrogen bond indicators in proteins

    International Nuclear Information System (INIS)

    Cierpicki, Tomasz; Otlewski, Jacek

    2001-01-01

    Correlations between amide proton temperature coefficients (Δσ HN /ΔT) and hydrogen bonds were investigated for a data set of 793 amides derived from 14 proteins. For amide protons showing temperature gradients more positive than -4.6 ppb/K there is a hydrogen bond predictivity value exceeding 85%. It increases to over 93% for amides within the range between -4 and -1 ppb/K. Detailed analysis shows an inverse proportionality between amide proton temperature coefficients and hydrogen bond lengths. Furthermore, for hydrogen bonds of similar bond lengths, values of temperature gradients in α-helices are on average 1 ppb/K more negative than in β-sheets. In consequence, a number of amide protons in α-helices involved in hydrogen bonds shorter than 2 A show Δσ HN /ΔT 10 helices and 98% in β-turns have temperature coefficients more positive than -4.6ppb/K. Ring current effect also significantly influences temperature coefficients of amide protons. In seven out of eight cases non-hydrogen bonded amides strongly deshielded by neighboring aromatic rings show temperature coefficients more positive than -2 ppb/K. In general, amide proton temperature gradients do not change with pH unless they correspond to conformational changes. Three examples of pH dependent equilibrium showing hydrogen bond formation at higher pH were found. In conclusion, amide proton temperature coefficients offer an attractive and simple way to confirm existence of hydrogen bonds in NMR determined structures

  18. 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.

  19. 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.

  20. Why are Hydrogen Bonds Directional?

    Indian Academy of Sciences (India)

    century and most chemists appear to think of 'chemi- cal bond' as ..... These complexes, in their global min- ima, have ... taneously act as hydrogen bond donor and acceptor displaying ... also has a local minimum, which is linear and similar to.

  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. Corporate Hybrid Bonds

    OpenAIRE

    Ahlberg, Johan; Jansson, Anton

    2016-01-01

    Hybrid securities do not constitute a new phenomenon in the Swedish capital markets. Most commonly, hybrids issued by Swedish real estate companies in recent years are preference shares. Corporate hybrid bonds on the other hand may be considered as somewhat of a new-born child in the family of hybrid instruments. These do, as all other hybrid securities, share some equity-like and some debt-like characteristics. Nevertheless, since 2013 the interest for the instrument has grown rapidly and ha...

  3. Hybrid Cat Bonds

    OpenAIRE

    Barrieu, Pauline; Louberge, Henri

    2009-01-01

    Natural catastrophes attract regularly the attention of media and have become a source of public concern. From a financial viewpoint, natural catastrophes represent idiosyncratic risks, diversifiable at the world level. But for reasons analyzed in this paper reinsurance markets are unable to cope with this risk completely. Insurance-linked securities, such as cat bonds, have been issued to complete the international risk transfer process, but their development is disappointing so far. This pa...

  4. Methods and system for controlled laser-driven explosive bonding

    Science.gov (United States)

    Rubenchik, Alexander M.; Farmer, Joseph C.; Hackel, Lloyd; Rankin, Jon

    2015-11-19

    A technique for bonding two dissimilar materials includes positioning a second material over a first material at an oblique angle and applying a tamping layer over the second martial. A laser beam is directed at the second material that generates a plasma at the location of impact on the second material. The plasma generates pressure that accelerates a portion of the second material to a very high velocity and towards the first material. The second material impacts the first material causing bonding of the two materials.

  5. 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...

  6. 46 CFR Sec. 10 - Bonds.

    Science.gov (United States)

    2010-10-01

    ... REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds. (a... awarded work and the furnishing of the performance and payment bonds required by Article 14 of the NSA... of the NSA-LUMPSUMREP Contract, the standard form of individual performance bond (Standard Form 25...

  7. Anomalous and resonance small-angle scattering

    International Nuclear Information System (INIS)

    Epperson, J.E.; Thiyagarajan, P.

    1988-01-01

    Significant changes in the small-angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous-dispersion terms for the scattering factor (X-rays) or scattering length (neutrons). The physics inherent in these anomalous-dispersion terms is first discussed before consideration of how they enter the relevant scattering theory. Two major areas of anomalous-scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with X-rays. However, it is pointed out that the formalism is the same for the analog experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small-angle neutron scattering are discussed. (orig.)

  8. Physical mechanisms of Cu-Cu wafer bonding

    International Nuclear Information System (INIS)

    Rebhan, B.

    2014-01-01

    Modern manufacturing processes of complex integrated semiconductor devices are based on wafer-level manufacturing of components which are subsequently interconnected. When compared with classical monolithic bi-dimensional integrated circuits (2D ICs), the new approach of three-dimensional integrated circuits (3D ICs) exhibits significant benefits in terms of signal propagation delay and power consumption due to the reduced metal interconnection length and allows high integration levels with reduced form factor. Metal thermo-compression bonding is a process suitable for 3D interconnects applications at wafer level, which facilitates the electrical and mechanical connection of two wafers even processed in different technologies, such as complementary metal oxide semiconductor (CMOS) and microelectromechanical systems (MEMS). Due to its high electrical conductivity, copper is a very attractive material for electrical interconnects. For Cu-Cu wafer bonding the process requires typically bonding for around 1 h at 400°C and high contact pressure applied during bonding. Temperature reduction below such values is required in order to solve issues regarding (i) throughput in the wafer bonder, (ii) wafer-to-wafer misalignment after bonding and (iii) to minimise thermo-mechanical stresses or device degradation. The aim of this work was to study the physical mechanisms of Cu-Cu bonding and based on this study to further optimise the bonding process for low temperatures. The critical sample parameters (roughness, oxide, crystallinity) were identified using selected analytical techniques and correlated with the characteristics of the bonded Cu-Cu interfaces. Based on the results of this study the impact of several materials and process specifications on the bonding result were theoretically defined and experimentally proven. These fundamental findings subsequently facilitated low temperature (LT) metal thermo-compression Cu-Cu wafer bonding and even room temperature direct

  9. Ab initio study of symmetrical tilt grain boundaries in bcc Fe: structural units, magnetic moments, interfacial bonding, local energy and local stress

    International Nuclear Information System (INIS)

    Bhattacharya, Somesh Kr; Tanaka, Shingo; Kohyama, Masanori; Shiihara, Yoshinori

    2013-01-01

    We present first-principle calculations on symmetric tilt grain boundaries (GBs) in bcc Fe. Using density functional theory (DFT), we studied the structural, electronic and magnetic properties of Σ3(111) and Σ11(332) GBs formed by rotation around the [110] axis. The optimized structures, GB energies and GB excess free volumes are consistent with previous DFT and classical simulation studies. The GB configurations can be interpreted by the structural unit model as given by Nakashima and Takeuchi (2000 ISIJ 86 357). Both the GBs are composed of similar structural units of three- and five-membered rings with different densities at the interface according to the rotation angle. The interface atoms with larger atomic volumes reveal higher magnetic moments than the bulk value, while the interface atoms with shorter bond lengths have reduced magnetic moments in each GB. The charge density and local density of states reveal that the interface bonds with short bond lengths have more covalent nature, where minority-spin electrons play a dominant role as the typical nature of ferromagnetic Fe. In order to understand the structural stability of these GBs, we calculated the local energy and local stress for each atomic region using the scheme of Shiihara et al (2010 Phys. Rev. B 81 075441). In each GB, the interface atoms with larger atomic volumes and enhanced magnetic moments reveal larger local energy increase and tensile stress. The interface atoms constituting more covalent-like bonds with reduced magnetic moments have lower local energy increase, contributing to the stabilization, while compressive stress is generated at these atoms. The relative stability between the two GBs can be understood by the local energies at the structural units. The local energy and local stress analysis is a powerful tool to investigate the structural properties of GBs based on the behavior of valence electrons. (paper)

  10. Pullout Performances of Grouted Rockbolt Systems with Bond Defects

    Science.gov (United States)

    Xu, Chang; Li, Zihan; Wang, Shanyong; Wang, Shuren; Fu, Lei; Tang, Chunan

    2018-03-01

    This paper presents a numerical study on the pullout behaviour of fully grouted rockbolts with bond defects. The cohesive zone model (CZM) is adopted to model the bond-slip behaviour between the rockbolt and grout material. Tensile tests were also conducted to validate the numerical model. The results indicate that the defect length can obviously influence the load and stress distributions along the rockbolt as well as the load-displacement response of the grouted system. Moreover, a plateau in the stress distribution forms due to the bond defect. The linear limit and peak load of the load-displacement response decrease as the defect length increases. A bond defect located closer to the loaded end leads to a longer nonlinear stage in the load-displacement response. However, the peak loads measured from the specimens made with various defect locations are almost approximately the same. The peak load for a specimen with the defects equally spaced along the bolt is higher than that for a specimen with defects concentrated in a certain zone, even with the same total defect length. Therefore, the dispersed pattern of bond defects would be much safer than the concentrated pattern. For the specimen with dispersed defects, the peak load increases with an increase in the defect spacing, even if the total defect length is the same. The peak load for a grouted rockbolt system with defects increases with an increases in the bolt diameter. This work leads to a better understanding of the load transfer mechanism for grouted rockbolt systems with bond defects, and paves the way towards developing a general evaluation method for damaged rockbolt grouted systems.

  11. Performance of various density functionals for the hydrogen bonds in DNA base pairs

    NARCIS (Netherlands)

    van der Wijst, T.; Fonseca Guerra, C.; Swart, M.; Bickelhaupt, F.M.

    2006-01-01

    We have investigated the performance of seven popular density functionals (B3LYP, BLYP, BP86, mPW, OPBE, PBE, PW91) for describing the geometry and stability of the hydrogen bonds in DNA base pairs. For the gas-phase situation, the hydrogen-bond lengths and strengths in the DNA pairs have been

  12. 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

  13. 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.

  14. A tensegrity model for hydrogen bond networks in proteins

    Directory of Open Access Journals (Sweden)

    Robert P. Bywater

    2017-05-01

    Full Text Available Hydrogen-bonding networks in proteins considered as structural tensile elements are in balance separately from any other stabilising interactions that may be in operation. The hydrogen bond arrangement in the network is reminiscent of tensegrity structures in architecture and sculpture. Tensegrity has been discussed before in cells and tissues and in proteins. In contrast to previous work only hydrogen bonds are studied here. The other interactions within proteins are either much stronger − covalent bonds connecting the atoms in the molecular skeleton or weaker forces like the so-called hydrophobic interactions. It has been demonstrated that the latter operate independently from hydrogen bonds. Each category of interaction must, if the protein is to have a stable structure, balance out. The hypothesis here is that the entire hydrogen bond network is in balance without any compensating contributions from other types of interaction. For sidechain-sidechain, sidechain-backbone and backbone-backbone hydrogen bonds in proteins, tensegrity balance (“closure” is required over the entire length of the polypeptide chain that defines individually folding units in globular proteins (“domains” as well as within the repeating elements in fibrous proteins that consist of extended chain structures. There is no closure to be found in extended structures that do not have repeating elements. This suggests an explanation as to why globular domains, as well as the repeat units in fibrous proteins, have to have a defined number of residues. Apart from networks of sidechain-sidechain hydrogen bonds there are certain key points at which this closure is achieved in the sidechain-backbone hydrogen bonds and these are associated with demarcation points at the start or end of stretches of secondary structure. Together, these three categories of hydrogen bond achieve the closure that is necessary for the stability of globular protein domains as well as repeating

  15. A tensegrity model for hydrogen bond networks in proteins.

    Science.gov (United States)

    Bywater, Robert P

    2017-05-01

    Hydrogen-bonding networks in proteins considered as structural tensile elements are in balance separately from any other stabilising interactions that may be in operation. The hydrogen bond arrangement in the network is reminiscent of tensegrity structures in architecture and sculpture. Tensegrity has been discussed before in cells and tissues and in proteins. In contrast to previous work only hydrogen bonds are studied here. The other interactions within proteins are either much stronger - covalent bonds connecting the atoms in the molecular skeleton or weaker forces like the so-called hydrophobic interactions. It has been demonstrated that the latter operate independently from hydrogen bonds. Each category of interaction must, if the protein is to have a stable structure, balance out. The hypothesis here is that the entire hydrogen bond network is in balance without any compensating contributions from other types of interaction. For sidechain-sidechain, sidechain-backbone and backbone-backbone hydrogen bonds in proteins, tensegrity balance ("closure") is required over the entire length of the polypeptide chain that defines individually folding units in globular proteins ("domains") as well as within the repeating elements in fibrous proteins that consist of extended chain structures. There is no closure to be found in extended structures that do not have repeating elements. This suggests an explanation as to why globular domains, as well as the repeat units in fibrous proteins, have to have a defined number of residues. Apart from networks of sidechain-sidechain hydrogen bonds there are certain key points at which this closure is achieved in the sidechain-backbone hydrogen bonds and these are associated with demarcation points at the start or end of stretches of secondary structure. Together, these three categories of hydrogen bond achieve the closure that is necessary for the stability of globular protein domains as well as repeating elements in fibrous proteins.

  16. Noise from Propellers with Symmetrical Sections at Zero Blade Angle

    Science.gov (United States)

    Deming, A F

    1937-01-01

    A theory has been deduced for the "rotation noise" from a propeller with blades of symmetrical section about the chord line and set at zero blade angle. Owing to the limitation of the theory, the equations give without appreciable error only the sound pressure for cases where the wave lengths are large compared with the blade lengths. With the aid of experimental data obtained from a two-blade arrangement, an empirical relation was introduced that permitted calculation of higher harmonics. The generality of the final relation given is indicated by the fundamental and second harmonic of a four-blade arrangement.

  17. Study of the Inception Length of Flow over Stepped Spillway Models ...

    African Journals Online (AJOL)

    The results showed that the inception (development) length increases as the unit discharge increases and it decreases with an increase in both stepped roughness height and chute angle. The ratio of the development length, in this study, to that of Bauer's was found to be 4:5. Finally, SMM-5 produced the least velocity of ...

  18. 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...

  19. Frequency scaling for angle gathers

    KAUST Repository

    Zuberi, M. A H; Alkhalifah, Tariq Ali

    2014-01-01

    Angle gathers provide an extra dimension to analyze the velocity after migration. Space-shift and time shift-imaging conditions are two methods used to obtain angle gathers, but both are reasonably expensive. By scaling the time-lag axis of the time-shifted images, the computational cost of the time shift imaging condition can be considerably reduced. In imaging and more so Full waveform inversion, frequencydomain Helmholtz solvers are used more often to solve for the wavefields than conventional time domain extrapolators. In such cases, we do not need to extend the image, instead we scale the frequency axis of the frequency domain image to obtain the angle gathers more efficiently. Application on synthetic data demonstrate such features.

  20. Angle imaging: Advances and challenges

    Science.gov (United States)

    Quek, Desmond T L; Nongpiur, Monisha E; Perera, Shamira A; Aung, Tin

    2011-01-01

    Primary angle closure glaucoma (PACG) is a major form of glaucoma in large populous countries in East and South Asia. The high visual morbidity from PACG is related to the destructive nature of the asymptomatic form of the disease. Early detection of anatomically narrow angles is important and the subsequent prevention of visual loss from PACG depends on an accurate assessment of the anterior chamber angle (ACA). This review paper discusses the advantages and limitations of newer ACA imaging technologies, namely ultrasound biomicroscopy, Scheimpflug photography, anterior segment optical coherence tomography and EyeCam, highlighting the current clinical evidence comparing these devices with each other and with clinical dynamic indentation gonioscopy, the current reference standard. PMID:21150037

  1. Comparison of different passive knee extension torque-angle assessments

    International Nuclear Information System (INIS)

    Freitas, Sandro R; Vaz, João R; Bruno, Paula M; Valamatos, Maria J; Mil-Homens, Pedro

    2013-01-01

    Previous studies have used isokinetic dynamometry to assess joint torques and angles during passive extension of the knee, often without reporting upon methodological errors and reliability outcomes. In addition, the reliability of the techniques used to measure passive knee extension torque-angle and the extent to which reliability may be affected by the position of the subjects is also unclear. Therefore, we conducted an analysis of the intra- and inter-session reliability of two methods of assessing passive knee extension: (A) a 2D kinematic analysis coupled to a custom-made device that enabled the direct measurement of resistance to stretch and (B) an isokinetic dynamometer used in two testing positions (with the non-tested thigh either flexed at 45° or in the neutral position). The intra-class correlation coefficients (ICCs) of torque, the slope of the torque-angle curve, and the parameters of the mathematical model that were fit to the torque-angle data for the above conditions were measured in sixteen healthy male subjects (age: 21.4 ± 2.1 yr; BMI: 22.6 ± 3.3 kg m −2 ; tibial length: 37.4 ± 3.4 cm). The results found were: (1) methods A and B led to distinctly different torque-angle responses; (2) passive torque-angle relationship and stretch tolerance were influenced by the position of the non-tested thigh; and (3) ICCs obtained for torque were higher than for the slope and for the mathematical parameters that were fit to the torque-angle curve. In conclusion, the measurement method that is used and the positioning of subjects can influence the passive knee extension torque-angle outcome. (paper)

  2. Research on the Bond Anchorage Properties of Alkali-Activated Slag Cementitious Material

    Science.gov (United States)

    Zhu, J.; Zheng, W. Z.; Leng, Y. F.; Qin, C. Z.; Xu, Z. Z.

    2017-12-01

    By bond-anchorage property tests at 20°C ∼500°C, the distribution of shear stress between carbon fiber sheets and concrete at all levels of loading and anchorage lengths were measured, which means the bond lengths during CFRP sheets are pulled off at the same time when the concrete is torn and stripped were gotten. The failure modes were obtained. In addition, the failure loads were measured, and the calculated formulas of anchorage lengths were identified by fitting at high temperature. It can be seen that the anchorage lengths of carbon fiber sheets increase with increasing temperature at 20°C ∼100°C, the anchorage lengths of carbon fiber sheets decrease with increasing temperature at 100°C ∼500°C. Tests prove that AASCM has favorable high-temperature resistant and bond anchorage properties.

  3. Silicate bonding properties: Investigation through thermal conductivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzini, M; Cesarini, E; Cagnoli, G; Campagna, E; Losurdo, G; Martelli, F; Piergiovanni, F; Vetrano, F [INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Haughian, K; Hough, J; Martin, I; Reid, S; Rowan, S; Veggel, A A van, E-mail: lorenzini@fi.infn.i [SUPA, University of Glasgow, Department of Physics and Astronomy, Kelvin Building G12 8QQ Glasgow, Scotland (United Kingdom)

    2010-05-01

    A direct approach to reduce the thermal noise contribution to the sensitivity limit of a GW interferometric detector is the cryogenic cooling of the mirrors and mirrors suspensions. Future generations of detectors are foreseen to implement this solution. Silicon has been proposed as a candidate material, thanks to its very low intrinsic loss angle at low temperatures and due to its very high thermal conductivity, allowing the heat deposited in the mirrors by high power lasers to be efficiently extracted. To accomplish such a scheme, both mirror masses and suspension elements must be made of silicon, then bonded together forming a quasi-monolithic stage. Elements can be assembled using hydroxide-catalysis silicate bonding, as for silica monolithic joints. The effect of Si to Si bonding on suspension thermal conductance has therefore to be experimentally studied. A measurement of the effect of silicate bonding on thermal conductance carried out on 1 inch thick silicon bonded samples, from room temperature down to 77 K, is reported. In the explored temperature range, the silicate bonding does not seem to affect in a relevant way the sample conductance.

  4. Angle independent velocity spectrum determination

    DEFF Research Database (Denmark)

    2014-01-01

    An ultrasound imaging system (100) includes a transducer array (102) that emits an ultrasound beam and produces at least one transverse pulse-echo field that oscillates in a direction transverse to the emitted ultrasound beam and that receive echoes produced in response thereto and a spectral vel...... velocity estimator (110) that determines a velocity spectrum for flowing structure, which flows at an angle of 90 degrees and flows at angles less than 90 degrees with respect to the emitted ultrasound beam, based on the received echoes....

  5. Temperature dependence of Brewster's angle.

    Science.gov (United States)

    Guo, Wei

    2018-01-01

    In this work, a dielectric at a finite temperature is modeled as an ensemble of identical atoms moving randomly around where they are trapped. Light reflection from the dielectric is then discussed in terms of atomic radiation. Specific calculation demonstrates that because of the atoms' thermal motion, Brewster's angle is, in principle, temperature-dependent, and the dependence is weak in the low-temperature limit. What is also found is that the Brewster's angle is nothing but a result of destructive superposition of electromagnetic radiation from the atoms.

  6. Evolution of the structure and hydrogen bonding configuration in annealed hydrogenated a-Si/a-Ge multilayers and layers

    International Nuclear Information System (INIS)

    Frigeri, C.; Nasi, L.; Serenyi, M.; Khanh, N.Q.; Csik, A.; Szekrenyes, Zs.; Kamaras, K.

    2012-01-01

    Complete text of publication follows. Among the present available renewable energy sources, energy harvesting from sunlight by means of photovoltaic cells is the most attractive one. In order to win over the traditional energy resources both efficiency and cost effectiveness of photovoltaic conversion must be optimized as far as possible. Efficiency is basically improved by the use of multijunction cells containing semiconductors with different band-gap. In this respect, the III-V compounds guarantee the highest efficiency, up to 41.6 %, but they are quite expensive. The latter drawback also affects other compounds like CdTe and CuIn 1-x Ga x Se 2 (CIGS). Si based solar devices have lower efficiency but are much more cost effective. They can use either crystalline or amorphous Si thin layers or Si nanoparticles. As to the thin films, amorphous Si (a-Si) is preferred to crystalline Si as it has a wider band-gap (1.7 instead of 1.1 eV) thus harvesting a larger portion of solar energy. A tandem cell is formed by using a-SiGe which has a smaller band-gap tunable between 1.1 and 1.7 eV depending on the Ge content. The best value should be 1.4 eV since the material properties seem to degrade below this value whilst the photo-conductivity drops after light soaking if the band gap exceeds 1.4 eV. A key issue of amorphous Si, Ge and SiGe is the high density of defects in the band-gap mostly due to dangling bonds whose density is particularly high (even up to 5 x10 19 cm -3 ) since the lattice is significantly disordered with distorted bond angles and lengths. This increases the probability of rupture of the Si-Si (Ge-Ge) bonds, i.e., formation of dangling bonds. Owing to the fact that hydrogen with its single electron structure can close the dangling bonds, their density can be reduced even by 4 orders of magnitude by doping with hydrogen. However, H is unstable in the host lattice. In fact, several findings showed its evolution from the thin layer upon annealing and that

  7. Influence of knee flexion angle and transverse drill angle on creation of femoral tunnels in double-bundle anterior cruciate ligament reconstruction using the transportal technique: Three-dimensional computed tomography simulation analysis.

    Science.gov (United States)

    Choi, Chong Hyuk; Kim, Sung-Jae; Chun, Yong-Min; Kim, Sung-Hwan; Lee, Su-Keon; Eom, Nam-Kyu; Jung, Min

    2018-01-01

    The purpose of this study was to find appropriate flexion angle and transverse drill angle for optimal femoral tunnels of anteromedial (AM) bundle and posterolateral (PL) bundle in double-bundle ACL reconstruction using transportal technique. Thirty three-dimensional knee models were reconstructed. Knee flexion angles were altered from 100° to 130° at intervals of 10°. Maximum transverse drill angle (MTA), MTA minus 10° and 20° were set up. Twelve different tunnels were determined by four flexion angles and three transverse drill angles for each bundle. Tunnel length, wall breakage, inter-tunnel communication and graft-bending angle were assessed. Mean tunnel length of AM bundle was >30mm at 120° and 130° of flexion in all transverse drill angles. Mean tunnel length of PL bundle was >30mm during every condition. There were ≥1 cases of wall breakage except at 120° and 130° of flexion with MTA for AM bundle. There was no case of wall breakage for PL bundle. Considering inter-tunnel gap of >2mm without communication and obtuse graft-bending angle, 120° of flexion and MTA could be recommended as optimal condition for femoral tunnels of AM and PL bundles. Flexion angle and transverse drill angle had combined effect on femoral tunnel in double-bundle ACL reconstruction using transportal technique. Achieving flexion angle of 120° and transverse drill angle close to the medial femoral condyle could be recommended as optimal condition for femoral tunnels of AM and PL bundles to avoid insufficient tunnel length, wall breakage, inter-tunnel communication and acute graft-bending angle. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Induced Smectic X Phase Through Intermolecular Hydrogen-Bonded Liquid Crystals Formed Between Citric Acid and p- n-(Octyloxy)Benzoic Acid

    Science.gov (United States)

    Sundaram, S.; Subhasri, P.; Rajasekaran, T. R.; Jayaprakasam, R.; Senthil, T. S.; Vijayakumar, V. N.

    2017-08-01

    Hydrogen-bonded liquid crystal (HBLC) is synthesized from citric acid (CA) and 4-(octyloxy)benzoic acid (8OBA) with different mole ratios. Fourier transform infrared spectroscopy (FT-IR) confirms the presence of hydrogen bond between CA and 8OBA. Nuclear magnetic resonance (NMR) spectroscopic studies validate the intermolecular complementary, cyclic type of hydrogen bond, and molecular environment in the designed HBLC complex. Powder X-ray diffraction analysis reveals the monoclinic nature of liquid crystal complex in solid phase. Liquid crystal parameters such as phase transition temperature and enthalpy values for the corresponding mesogenic phases are investigated using a polarizing optical microscope (POM) and differential scanning calorimetry (DSC). It is observed that the change in chain length and steric hindrance while increasing the mole ratio in HBLC complex induces a new smectic X (Sm X) along with higher-order smectic G (Sm G) phases by quenching of smectic C (Sm C). From the experimental observations, induced Sm X phase has been identified as a finger print texture. Also, Sm G is a multi-colored mosaic texture in 1:1, 1:2, and 1:3 mol ratios. The optical tilt angle, thermal stability factor, and enhanced thermal span width of CA + 8OBA complex are discussed.

  9. Influence of body mass and lower limb length on knee flexion angle during walking in humans

    Czech Academy of Sciences Publication Activity Database

    Hora, M.; Sládek, Vladimír; Soumar, L.; Stráníková, K.; Michálek, T.

    2012-01-01

    Roč. 61, 3-4 (2012), s. 330-339 ISSN 0139-7893 R&D Projects: GA ČR GA206/09/0589 Institutional support: RVO:68081766 Keywords : size * posture * locomotion * biomechanics Subject RIV: EG - Zoology Impact factor: 0.494, year: 2012

  10. Neuromuscular adaptations associated with knee joint angle-specific force change.

    Science.gov (United States)

    Noorkõiv, Marika; Nosaka, Kazunori; Blazevich, Anthony J

    2014-08-01

    Neuromuscular adaptations to joint angle-specific force increases after isometric training have not yet been fully elucidated. This study examined angle-specific neuromuscular adaptations in response to isometric knee extension training at short (SL, joint angle 38.1° ± 3.7°) versus long (LL, 87.5° ± 6.0°) muscle lengths. Sixteen men trained three times a week for 6 wk either at SL (n = 8) or LL (n = 8). Voluntary maximal isometric knee extensor (MVC) force, doublet twitch force, EMG amplitudes (EMG/Mmax), and voluntary activation during MVC force (VA%) were measured at eight knee joint angles (30°-100°) at weeks 0, 3, and 6. Muscle volume and cross-sectional area (CSA) were measured from magnetic resonance imaging scans, and fascicle length (Lf) was assessed using ultrasonography before and after training. Clear joint angle specificity of force increase was seen in SL but not in LL. The 13.4% ± 9.7% (P = 0.01) force increase around the training angle in SL was related to changes in vastus lateralis and vastus medialis EMG/Mmax around the training angle (r = 0.84-0.88, P < 0.05), without changes in the doublet twitch force-angle relation or muscle size. In LL, muscle volume and CSA increased and the changes in CSA at specific muscle regions were correlated with changes in MVC force. A 5.4% ± 4.9% (P = 0.001) increase in Lf found in both groups was not associated with angle-specific force changes. There were no angle-specific changes in VA%. The EMG/Mmax, although not VA%, results suggest that neural adaptations underpinned training-related changes at short quadriceps lengths, but hypertrophic changes predominated after training at long lengths. The findings of this study should contribute to the development of more effective and evidence-based rehabilitation and strength training protocols.

  11. Effect of canal length and curvature on working length alteration with WaveOne reciprocating files.

    Science.gov (United States)

    Berutti, Elio; Chiandussi, Giorgio; Paolino, Davide Salvatore; Scotti, Nicola; Cantatore, Giuseppe; Castellucci, Arnaldo; Pasqualini, Damiano

    2011-12-01

    This study evaluated the working length (WL) modification after instrumentation with WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) reciprocating files and the incidence of overinstrumentation in relation to the initial WL. Thirty-two root canals of permanent teeth were used. The angles of curvature of the canals were calculated on digital radiographs. The initial WL with K-files was transferred to the matched WaveOne Primary reciprocating files. After glide paths were established with PathFile (Dentsply Maillefer, Ballaigues, Switzerland), canals were shaped with WaveOne Primary referring to the initial WL. The difference between the postinstrumentation canal length and the initial canal length was analyzed by using a fiberoptic inspection microscope. Data were analyzed with a balanced 2-way factorial analysis of variance (P < .05). Referring to the initial WL, 24 of 32 WaveOne Primary files projected beyond the experimental apical foramen (minimum-maximum, 0.14-0.76 mm). A significant decrease in the canal length after instrumentation (95% confidence interval ranging from -0.34 mm to -0.26 mm) was detected. The canal curvature significantly influenced the WL variation (F(1) = 30.65, P < .001). The interaction between the initial canal length and the canal curvature was statistically significant (F(2) = 4.38, P = .014). Checking the WL before preparation of the apical third of the root canal is recommended when using the new WaveOne NiTi single-file system. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Interplay between Peptide Bond Geometrical Parameters in Nonglobular Structural Contexts

    Directory of Open Access Journals (Sweden)

    Luciana Esposito

    2013-01-01

    Full Text Available Several investigations performed in the last two decades have unveiled that geometrical parameters of protein backbone show a remarkable variability. Although these studies have provided interesting insights into one of the basic aspects of protein structure, they have been conducted on globular and water-soluble proteins. We report here a detailed analysis of backbone geometrical parameters in nonglobular proteins/peptides. We considered membrane proteins and two distinct fibrous systems (amyloid-forming and collagen-like peptides. Present data show that in these systems the local conformation plays a major role in dictating the amplitude of the bond angle N-Cα-C and the propensity of the peptide bond to adopt planar/nonplanar states. Since the trends detected here are in line with the concept of the mutual influence of local geometry and conformation previously established for globular and water-soluble proteins, our analysis demonstrates that the interplay of backbone geometrical parameters is an intrinsic and general property of protein/peptide structures that is preserved also in nonglobular contexts. For amyloid-forming peptides significant distortions of the N-Cα-C bond angle, indicative of sterical hidden strain, may occur in correspondence with side chain interdigitation. The correlation between the dihedral angles Δω/ψ in collagen-like models may have interesting implications for triple helix stability.

  13. Interplay between peptide bond geometrical parameters in nonglobular structural contexts.

    Science.gov (United States)

    Esposito, Luciana; Balasco, Nicole; De Simone, Alfonso; Berisio, Rita; Vitagliano, Luigi

    2013-01-01

    Several investigations performed in the last two decades have unveiled that geometrical parameters of protein backbone show a remarkable variability. Although these studies have provided interesting insights into one of the basic aspects of protein structure, they have been conducted on globular and water-soluble proteins. We report here a detailed analysis of backbone geometrical parameters in nonglobular proteins/peptides. We considered membrane proteins and two distinct fibrous systems (amyloid-forming and collagen-like peptides). Present data show that in these systems the local conformation plays a major role in dictating the amplitude of the bond angle N-C(α)-C and the propensity of the peptide bond to adopt planar/nonplanar states. Since the trends detected here are in line with the concept of the mutual influence of local geometry and conformation previously established for globular and water-soluble proteins, our analysis demonstrates that the interplay of backbone geometrical parameters is an intrinsic and general property of protein/peptide structures that is preserved also in nonglobular contexts. For amyloid-forming peptides significant distortions of the N-C(α)-C bond angle, indicative of sterical hidden strain, may occur in correspondence with side chain interdigitation. The correlation between the dihedral angles Δω/ψ in collagen-like models may have interesting implications for triple helix stability.

  14. Driving force for hydrophobic interaction at different length scales.

    Science.gov (United States)

    Zangi, Ronen

    2011-03-17

    We study by molecular dynamics simulations the driving force for the hydrophobic interaction between graphene sheets of different sizes down to the atomic scale. Similar to the prediction by Lum, Chandler, and Weeks for hard-sphere solvation [J. Phys. Chem. B 1999, 103, 4570-4577], we find the driving force to be length-scale dependent, despite the fact that our model systems do not exhibit dewetting. For small hydrophobic solutes, the association is purely entropic, while enthalpy favors dissociation. The latter is demonstrated to arise from the enhancement of hydrogen bonding between the water molecules around small hydrophobes. On the other hand, the attraction between large graphene sheets is dominated by enthalpy which mainly originates from direct solute-solute interactions. The crossover length is found to be inside the range of 0.3-1.5 nm(2) of the surface area of the hydrophobe that is eliminated in the association process. In the large-scale regime, different thermodynamic properties are scalable with this change of surface area. In particular, upon dimerization, a total and a water-induced stabilization of approximately 65 and 12 kJ/mol/nm(2) are obtained, respectively, and on average around one hydrogen bond is gained per 1 nm(2) of graphene sheet association. Furthermore, the potential of mean force between the sheets is also scalable except for interplate distances smaller than 0.64 nm which corresponds to the region around the barrier for removing the last layer of water. It turns out that, as the surface area increases, the relative height of the barrier for association decreases and the range of attraction increases. It is also shown that, around small hydrophobic solutes, the lifetime of the hydrogen bonds is longer than in the bulk, while around large hydrophobes it is the same. Nevertheless, the rearrangement of the hydrogen-bond network for both length-scale regimes is slower than in bulk water. © 2011 American Chemical Society

  15. Control of concerted two bond versus single bond dissociation in CH3Co(CO)4 via an intermediate state using pump-dump laser pulses

    Science.gov (United States)

    Ambrosek, David; González, Leticia

    2007-10-01

    Wavepacket propagations on ab initio multiconfigurational two-dimensional potential energy surfaces for CH3Co(CO)4 indicate that after irradiation to the lowest first and second electronic excited states, concerted dissociation of CH3 and the axial CO ligand takes place. We employ a pump-dump sequence of pulses with appropriate frequencies and time delays to achieve the selective breakage of a single bond by controlling the dissociation angle. The pump and dump pulse sequence exploits the unbound surface where dissociation occurs in a counterintuitive fashion; stretching of one bond in an intermediate state enhances the single dissociation of the other bond.

  16. Control of concerted two bond versus single bond dissociation in CH(3)Co(CO)(4) via an intermediate state using pump-dump laser pulses.

    Science.gov (United States)

    Ambrosek, David; González, Leticia

    2007-10-07

    Wavepacket propagations on ab initio multiconfigurational two-dimensional potential energy surfaces for CH(3)Co(CO)(4) indicate that after irradiation to the lowest first and second electronic excited states, concerted dissociation of CH(3) and the axial CO ligand takes place. We employ a pump-dump sequence of pulses with appropriate frequencies and time delays to achieve the selective breakage of a single bond by controlling the dissociation angle. The pump and dump pulse sequence exploits the unbound surface where dissociation occurs in a counterintuitive fashion; stretching of one bond in an intermediate state enhances the single dissociation of the other bond.

  17. Multi-angle compound imaging

    DEFF Research Database (Denmark)

    Jespersen, Søren Kragh; Wilhjelm, Jens Erik; Sillesen, Henrik

    1998-01-01

    This paper reports on a scanning technique, denoted multi-angle compound imaging (MACI), using spatial compounding. The MACI method also contains elements of frequency compounding, as the transmit frequency is lowered for the highest beam angles in order to reduce grating lobes. Compared to conve......This paper reports on a scanning technique, denoted multi-angle compound imaging (MACI), using spatial compounding. The MACI method also contains elements of frequency compounding, as the transmit frequency is lowered for the highest beam angles in order to reduce grating lobes. Compared...... to conventional B-mode imaging MACI offers better defined tissue boundaries and lower variance of the speckle pattern, resulting in an image with reduced random variations. Design and implementation of a compound imaging system is described, images of rubber tubes and porcine aorta are shown and effects...... on visualization are discussed. The speckle reduction is analyzed numerically and the results are found to be in excellent agreement with existing theory. An investigation of detectability of low-contrast lesions shows significant improvements compared to conventional imaging. Finally, possibilities for improving...

  18. Femoral varus: what's the angle

    DEFF Research Database (Denmark)

    Miles, James Edward; Svalastoga, Eiliv Lars; Eriksen, Thomas

    angles were calculated using Microsoft Excel for the three previously reported techniques and a novel method, which we believed would be more reliable. Reliability between readings was assessed using the within-subject standard deviation and repeatability coefficient, and the effect of angulation...

  19. FR4-Based Electromagnetic Scanning Micromirror Integrated with Angle Sensor

    Directory of Open Access Journals (Sweden)

    Hongjie Lei

    2018-05-01

    Full Text Available This paper presents a flame retardant 4 (FR4-based electromagnetic scanning micromirror, which aims to overcome the limitations of conventional microelectromechanical systems (MEMS micromirrors for the large-aperture and low-frequency scanning applications. This micromirror is fabricated through a commercial printed circuit board (PCB technology at a low cost and with a short process cycle, before an aluminum-coated silicon mirror plate with a large aperture is bonded on the FR4 platform to provide a high surface quality. In particular, an electromagnetic angle sensor is integrated to monitor the motion of the micromirror in real time. A prototype has been assembled and tested. The results show that the micromirror can reach the optical scan angle of 11.2 ∘ with a low driving voltage of only 425 mV at resonance (361.8 Hz. At the same time, the signal of the integrated angle sensor also shows good signal-to-noise ratio, linearity and sensitivity. Finally, the reliability of the FR4 based micro-mirror has been tested. The prototype successfully passes both shock and vibration tests. Furthermore, the results of the long-term mechanical cycling test (50 million cycles suggest that the maximum variations of resonant frequency and scan angle are less than 0.3% and 6%, respectively. Therefore, this simple and robust micromirror has great potential in being useful in a number of optical microsystems, especially when large-aperture or low-frequency is required.

  20. Topology of charge density of flucytosine and related molecules and characteristics of their bond charge distributions.

    Science.gov (United States)

    Murgich, Juan; Franco, Héctor J; San-Blas, Gioconda

    2006-08-24

    The molecular charge distribution of flucytosine (4-amino-5-fluoro-2-pyrimidone), uracil, 5-fluorouracil, and thymine was studied by means of density functional theory calculations (DFT). The resulting distributions were analyzed by means of the atoms in molecules (AIM) theory. Bonds were characterized through vectors formed with the charge density value, its Laplacian, and the bond ellipticity calculated at the bond critical point (BCP). Within each set of C=O, C-H, and N-H bonds, these vectors showed little dispersion. C-C bonds formed three different subsets, one with a significant degree of double bonding, a second corresponding to single bonds with a finite ellipticity produced by hyperconjugation, and a third one formed by a pure single bond. In N-C bonds, a decrease in bond length (an increase in double bond character) was not reflected as an increase in their ellipticity, as in all C-C bonds studied. It was also found that substitution influenced the N-C, C-O, and C-C bond ellipticity much more than density and its Laplacian at the BCP. The Laplacian of charge density pointed to the existence of both bonding and nonbonding maxima in the valence shell charge concentration of N, O, and F, while only bonding ones were found for the C atoms. The nonbonding maxima related to the sites for electrophilic attack and H bonding in O and N, while sites of nucleophilic attack were suggested by the holes in the valence shell of the C atoms of the carbonyl groups.

  1. Fatigue aging of adhesive bonds

    International Nuclear Information System (INIS)

    DeLollis, N.J.

    1979-01-01

    A year long study has been made of the effect of fatigue on the bond between two epoxy encapsulant formulations and a fused alumina disc. The variables studied included isothermal aging at temperatures up to and including the cure temperature and cyclic thermal aging from +74 to -54 0 C. The encapsulants were glass microballoon filled epoxies differing only in curing agents. One was cured with an aromatic amine eutectic (Shell Curing Agent Z). The other was cured with diethanolamine. The Z cured encapsulant bond failed completely at the bond interface with little or no aging; infrared evidence indicated a soluble interlayer as a possible cause of failure. The diethanolamine cured encapsulant survived a year of isothermal aging with little or no evidence of bond degradation. Cyclic thermal aging resulted in gradual bond failure with time. An extrapolation of the cyclic aging data indicates that the stresses induced by thermal cycling would result in complete bond failure in about 1200 days

  2. Increasing FSW join strength by optimizing feed rate, rotating speed and pin angle

    Science.gov (United States)

    Darmadi, Djarot B.; Purnowidodo, Anindito; Siswanto, Eko

    2017-10-01

    Principally the join in Friction Stir Welding (FSW) is formed due to mechanical bonding. At least there are two factors determines the quality of this join, first is the temperature in the area around the interface and secondly the intense of mixing forces in nugget zone to create the mechanical bonding. The adequate temperature creates good flowability of the nugget zone and an intensive mixing force produces homogeneous strong bonding. Based on those two factors in this research the effects of feed rate, rotating speed and pin angle of the FSW process to the tensile strength of resulted join are studied. The true experimental method was used. Feed rate was varied at 24, 42, 55 and 74 mm/minutes and from the experimental results, it can be concluded that the higher feed rate decreases the tensile strength of weld join and it is believed due to the lower heat embedded in the material. Inversely, the higher rotating speed increases the join’s tensile strength as a result of higher heat embedded in base metal and higher mixing force in the nugget zone. The rotating speed were 1842, 2257 and 2904 RPMs. The pin angle determines the direction of mixing force. With variation of pin angle: 0°, 4°, 8° and 12° the higher pin angle generally increases the tensile strength because of more intensive mixing force. For 12° pin angle the lower tensile strength is found since the force tends to push out the nugget area from the joint gap.

  3. How Is the Enamel Affected by Different Orthodontic Bonding Agents and Polishing Techniques?

    Directory of Open Access Journals (Sweden)

    Farzin Heravi

    2015-10-01

    Full Text Available Objectives: The objective of this study was to assess the effect of new bonding techniques on enamel surface.Materials and Methods: Sixty upper central incisors were randomly divided into two equal groups. In the first group, metal brackets were bonded using Trans- bondXT and, in the second group, the same brackets were bonded with MaxcemElite. The shear bond strength (SBS of both agents to enamel was measured and the number and length of enamel cracks before bonding, after debonding and after polishing were compared. The number of visible cracks and the adhesive remnant index (ARI scores in each group were also measured.Results: There were significantly more enamel cracks in the Transbond XT group after debonding and polishing compared to the Maxcem Elite group. There was no significant difference in the length of enamel cracks between the two groups; but, in each group, a significant increase in the length of enamel cracks was noticeable after debonding. Polishing did not cause any statistically significant change in crack length. The SBS of Maxcem Elite was significantly lower than that of Transbond XT (95% confidence interval.Conclusion: Maxcem Elite offers clinically acceptable bond strength and can thus be used as a routine adhesive for orthodontic purposes since it is less likely todamage the enamel.

  4. Composite interlayer for diffusion bonding

    International Nuclear Information System (INIS)

    1976-01-01

    A ductile interlayer is described, which is useful for transient liquid phase diffusion bonding of metallic articles; the interlayer consisting of a melting point depressant and a plurality of ductile lamellae which are free from carbides, aluminides and borides. The composition and fabrication of the lamellae, and the process for bonding the metallic articles, depend on the composition of the metals to be bonded, and are exemplified in the specification. (U.K.)

  5. Contact angle of a nanodrop on a nanorough solid surface.

    Science.gov (United States)

    Berim, Gersh O; Ruckenstein, Eli

    2015-02-21

    The contact angle of a cylindrical nanodrop on a nanorough solid surface is calculated, for both hydrophobic and hydrophilic surfaces, using the density functional theory. The emphasis of the paper is on the dependence of the contact angle on roughness. The roughness is modeled by rectangular pillars of infinite length located on the smooth surface of a substrate, with fluid-pillar interactions different in strength from the fluid-substrate ones. It is shown that for hydrophobic substrates the trend of the contact angle to increase with increasing roughness, which was noted in all previous studies, is not universally valid, but depends on the fluid-pillar interactions, pillar height, interpillar distance, as well as on the size of the drop. For hydrophilic substrate, an unusual kink-like dependence of the contact angle on the nanodrop size is found which is caused by the change in the location of the leading edges of the nanodrop on the surface. It is also shown that the Wenzel and Cassie-Baxter equations can not explain all the peculiarities of the contact angle of a nanodrop on a nanorough surface.

  6. Effects of interface edge configuration on residual stress in the bonded structures for a divertor application

    International Nuclear Information System (INIS)

    Kitamura, K.; Nagata, K.; Shibui, M.; Tachikawa, N.; Araki, M.

    1998-01-01

    Residual stresses in the interface region, that developed at the cool down during the brazing, were evaluated for several bonded structures to assess the mechanical strength of the bonded interface, using thermoelasto-plastic stress analysis. Normal stress components of the residual stresses around the interface edge of graphite-copper (C-Cu) bonded structures were compared for three types of bonded features such as flat-type, monoblock-type and saddle-type. The saddle-type structure was found to be favorable for its relatively low residual stress, easy fabrication accuracy on bonded interface and armor replacement. Residual stresses around the interface edge in three armor materials/copper bonded structures for a divertor plate were also examined for the C-Cu, tungsten-copper (W-Cu) and molybdenum alloy-copper (TZM-Cu), varying the interface wedge angle from 45 to 135 . An optimal bonded configuration for the least value of residual stress was found to have a wedge angle of 45 for the C-Cu, and 135 for both the W-Cu and TZM-Cu bonded ones. (orig.)

  7. 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.

  8. 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.

  9. 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....

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

    International Nuclear Information System (INIS)

    Freire, J J

    2008-01-01

    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

  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. 30 CFR 281.33 - Bonds and bonding requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Bonds and bonding requirements. 281.33 Section 281.33 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL, GAS, AND SULPHUR IN THE OUTER CONTINENTAL SHELF Financial Considerations § 281.33...

  13. 29 CFR 2580.412-19 - Term of the bond, discovery period, other bond clauses.

    Science.gov (United States)

    2010-07-01

    ... SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules § 2580.412-19 Term of the bond, discovery... 29 Labor 9 2010-07-01 2010-07-01 false Term of the bond, discovery period, other bond clauses... new bond must be obtained each year. There is nothing in the Act that prohibits a bond for a term...

  14. Theoretical determination of molecular structure and conformation. 20. Reevaluation of the strain energies of cyclopropane and cyclobutane - CC and CH bond energies, 1,3 interactions, and sigma-aromaticity

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, D.; Gauss, J.

    1986-11-26

    In order to rationalize the striking similarity of the strain energies (SE) of cyclopropane (1, 28 kcal/mol) and cyclobutane (2, 27 kcal/mol), the energetic consequences of Pitzer strain, Baeyer strain, hybridization effects (CH bond strengthening), Dunitz-Schomaker strain (1,3 CC interactions), and bond stretching effects have been quantitatively assessed at the HF/6-31G** level of theory. Calculations have been based on chemically meaningful definitions of bond length, bond angle, bond energy, and bending force constant in strained molecules. Results reveal that Pitzer strain in both 1 and 2 is just 4 kcal/mol and that CH bond strengthening stabilizes 1 by 6 kcal/mol (2 by 3 kcal/mol), far less than has been assumed previously. The calculated Baeyer strain of 1 and 2 is 41 and 13 kcal/mol, respectively. SE(1) and SE(2) can only be compared if a correction term of 9 kcal/mol due to Dunitz-Schomaker strain (present in 2, but absent in 1) is taken into account. The analysis of the various energy contributions to the SEs of 1 and 2 reveals that 1 is stabilized by at least 17 kcal/mol. Both MO and electron density analysis suggest that 1 is totally different from the other cycloalkanes in being stabilized by 3-center 2-electron delocalization. sigma-Electrons are delocalized in the surface of the three-membered ring, a phenomenon which may be described by the term sigma-aromaticity.

  15. Contact angles on stretched solids

    Science.gov (United States)

    Mensink, Liz; Snoeijer, Jacco

    2017-11-01

    The surface energy of solid interfaces plays a central role in wetting, as they dictate the liquid contact angle. Yet, it has been challenging to measure the solid surface energies independently, without making use of Young's law. Here we present Molecular Dynamics (MD) simulations by which we measure the surface properties for all interfaces, including the solids. We observe change in contact angles upon stretching the solid substrates, showing that the surface energy is actually strain dependent. This is clear evidence of the so-called Shuttleworth effect, making it necessary to distinguish surface energy from surface tension. We discuss how this effect gives rise to a new class of elasto-capillary phenomena. ERC Consolidator Grant No. 616918.

  16. Disorders of the cerebellopontine angle

    International Nuclear Information System (INIS)

    Block, F.

    2006-01-01

    Disorders of the cerebellopontine angle may present by symptoms like vertigo, hearing problems, affection of the trigeminal or facial nerve. Ipsilateral ataxia and contralateral hemiparesis develop in case of a rather large tumor in this region and display an involvement of the cerebellum and/or brainstem. However, some of these typical symptoms are not recognized by the patient. Thus, in case of a suspicion of a disorder of the cerebellopontine angle the relevant functions have to be tested clinically. In addition, electrophysiology can confirm dysfunction of these cranial nerves. Mainstay of the therapy should be the treatment of the underlying cause. Nevertheless, not seldom it is necessary to treat symptoms like vertigo or facial pain. (orig.) [de

  17. Measurement of the angle gamma

    International Nuclear Information System (INIS)

    Aleksan, R.; Kayser, B.; Sphicas, P.

    1993-01-01

    The angle γ at least as defined in the Wolfenstein approximation is not completely out of reach of current or proposed dedicated B experiments. This conclusion certainly depends crucially on the assumed trigger and tagging efficiencies and also on the expected backgrounds. The work summarized here represents but a first step in the direction of extracting the third angle of the unitarity triangle. The theoretical developments during the workshop have resulted in a clearer understanding of the quantities studied. On the experimental side, new decay modes (i.e. in addition to the traditional ρK s decay) have resulted in expections for observing CP violation in B s decays which are not unreasonable. It is conceivable that a dedicated B experiment can probe a fundamental aspect of the Standard Model, the CKM matrix, in multiple ways. In the process, new physics can appear anywhere along the line

  18. Short hydrogen bonds in the catalytic mechanism of serine proteases

    Directory of Open Access Journals (Sweden)

    VLADIMIR LESKOVAC

    2008-04-01

    Full Text Available The survey of crystallographic data from the Protein Data Bank for 37 structures of trypsin and other serine proteases at a resolution of 0.78–1.28 Å revealed the presence of hydrogen bonds in the active site of the enzymes, which are formed between the catalytic histidine and aspartate residues and are on average 2.7 Å long. This is the typical bond length for normal hydrogen bonds. The geometric properties of the hydrogen bonds in the active site indicate that the H atom is not centered between the heteroatoms of the catalytic histidine and aspartate residues in the active site. Taken together, these findings exclude the possibility that short “low-barrier” hydrogen bonds are formed in the ground state structure of the active sites examined in this work. Some time ago, it was suggested by Cleland that the “low-barrier hydrogen bond” hypothesis is operative in the catalytic mechanism of serine proteases, and requires the presence of short hydrogen bonds around 2.4 Å long in the active site, with the H atom centered between the catalytic heteroatoms. The conclusions drawn from this work do not exclude the validity of the “low-barrier hydrogen bond” hypothesis at all, but they merely do not support it in this particular case, with this particular class of enzymes.

  19. Noble gas bond and the behaviour of XeO3 under pressure.

    Science.gov (United States)

    Hou, Chunju; Wang, Xianlong; Botana, Jorge; Miao, Maosheng

    2017-10-18

    Over the past few decades, the concept of hydrogen bonds, in which hydrogen is electrophilic, has been extended to halogen bonds, chalcogen bonds and pnicogen bonds. Herein, we show that such a non-covalent bonding also exists in noble gas compounds. Using first principles calculations, we illustrate the OXe-O bond in molecular crystal XeO 3 and its effect on the behavior of this compound under pressure. Our calculations show that the covalent Xe-O bond lengths were elongated with increasing pressure and correspondingly the Xe-O stretching vibration frequencies were red shifted, which is similar to the change of H-bonds under pressure. The OXe-O bond and related hopping of O between neighboring Xe sites also correspond to the structural changes in the XeO 3 compounds at about 2 GPa. Our study extends the concept of hydrogen bonding to include all p-block elements and show a new bonding type for Noble gas elements in which it acts as an electrophilic species.

  20. LHC Report: playing with angles

    CERN Multimedia

    Mike Lamont for the LHC team

    2016-01-01

    Ready (after a machine development period), steady (running), go (for a special run)!   The crossing angles are an essential feature of the machine set-up. They have to be big enough to reduce the long-range beam-beam effect. The LHC has recently enjoyed a period of steady running and managed to set a new record for “Maximum Stable Luminosity Delivered in 7 days” of 3.29 fb-1 between 29 August and 4 September. The number of bunches per beam remains pegged at 2220 because of the limitations imposed by the SPS beam dump. The bunch population is also somewhat reduced due to outgassing near one of the injection kickers at point 8. Both limitations will be addressed during the year-end technical stop, opening the way for increased performance in 2017. On 10 and 11 September, a two day machine development (MD) period took place. The MD programme included a look at the possibility of reducing the crossing angle at the high-luminosity interaction points. The crossing angles are an ess...

  1. Light Scattering at Various Angles

    Science.gov (United States)

    Latimer, Paul; Pyle, B. E.

    1972-01-01

    The Mie theory of scattering is used to provide new information on how changes in particle volume, with no change in dry weight, should influence light scattering for various scattering angles and particle sizes. Many biological cells (e.g., algal cells, erythrocytes) and large subcellular structures (e.g., chloroplasts, mitochondria) in suspension undergo this type of reversible volume change, a change which is related to changes in the rates of cellular processes. A previous study examined the effects of such volume changes on total scattering. In this paper scattering at 10° is found to follow total scattering closely, but scattering at 45°, 90°, 135°, and 170° behaves differently. Small volume changes can cause very large observable changes in large angle scattering if the sample particles are uniform in size; however, the natural particle size heterogeneity of most samples would mask this effect. For heterogeneous samples of most particle size ranges, particle shrink-age is found to increase large angle scattering. PMID:4556610

  2. Angle comparison using an autocollimator

    Science.gov (United States)

    Geckeler, Ralf D.; Just, Andreas; Vasilev, Valentin; Prieto, Emilio; Dvorácek, František; Zelenika, Slobodan; Przybylska, Joanna; Duta, Alexandru; Victorov, Ilya; Pisani, Marco; Saraiva, Fernanda; Salgado, Jose-Antonio; Gao, Sitian; Anusorn, Tonmueanwai; Leng Tan, Siew; Cox, Peter; Watanabe, Tsukasa; Lewis, Andrew; Chaudhary, K. P.; Thalmann, Ruedi; Banreti, Edit; Nurul, Alfiyati; Fira, Roman; Yandayan, Tanfer; Chekirda, Konstantin; Bergmans, Rob; Lassila, Antti

    2018-01-01

    Autocollimators are versatile optical devices for the contactless measurement of the tilt angles of reflecting surfaces. An international key comparison (KC) on autocollimator calibration, EURAMET.L-K3.2009, was initiated by the European Association of National Metrology Institutes (EURAMET) to provide information on the capabilities in this field. The Physikalisch-Technische Bundesanstalt (PTB) acted as the pilot laboratory, with a total of 25 international participants from EURAMET and from the Asia Pacific Metrology Programme (APMP) providing measurements. This KC was the first one to utilise a high-resolution electronic autocollimator as a standard. In contrast to KCs in angle metrology which usually involve the full plane angle, it focused on relatively small angular ranges (+/-10 arcsec and +/-1000 arcsec) and step sizes (10 arcsec and 0.1 arcsec, respectively). This document represents the approved final report on the results of the KC. 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 CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  3. 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.

  4. Does length or neighborhood size cause the word length effect?

    Science.gov (United States)

    Jalbert, Annie; Neath, Ian; Surprenant, Aimée M

    2011-10-01

    Jalbert, Neath, Bireta, and Surprenant (2011) suggested that past demonstrations of the word length effect, the finding that words with fewer syllables are recalled better than words with more syllables, included a confound: The short words had more orthographic neighbors than the long words. The experiments reported here test two predictions that would follow if neighborhood size is a more important factor than word length. In Experiment 1, we found that concurrent articulation removed the effect of neighborhood size, just as it removes the effect of word length. Experiment 2 demonstrated that this pattern is also found with nonwords. For Experiment 3, we factorially manipulated length and neighborhood size, and found only effects of the latter. These results are problematic for any theory of memory that includes decay offset by rehearsal, but they are consistent with accounts that include a redintegrative stage that is susceptible to disruption by noise. The results also confirm the importance of lexical and linguistic factors on memory tasks thought to tap short-term memory.

  5. O hydrogen bonds in alkaloids

    Indian Academy of Sciences (India)

    An overview of general classification scheme, medicinal importance and crystal structure analysis with emphasis on the role of hydrogen bonding in some alkaloids is presented in this paper. The article is based on a general kind of survey while crystallographic analysis and role of hydrogen bonding are limited to only ...

  6. 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.

  7. 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...

  8. 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

  9. Influences of Fascicle Length During Isometric Training on Improvement of Muscle Strength.

    Science.gov (United States)

    Tanaka, Hiroki; Ikezoe, Tome; Umehara, Jun; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Nishishita, Satoru; Fujita, Kosuke; Araki, Kojiro; Ichihashi, Noriaki

    2016-11-01

    Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249-3255, 2016-This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.

  10. Keeping disease at arm's length

    DEFF Research Database (Denmark)

    Lassen, Aske Juul

    2015-01-01

    active ageing change everyday life with chronic disease, and how do older people combine an active life with a range of chronic diseases? The participants in the study use activities to keep their diseases at arm’s length, and this distancing of disease at the same time enables them to engage in social...... and physical activities at the activity centre. In this way, keeping disease at arm’s length is analysed as an ambiguous health strategy. The article shows the importance of looking into how active ageing is practised, as active ageing seems to work well in the everyday life of the older people by not giving...... emphasis to disease. The article is based on ethnographic fieldwork and uses vignettes of four participants to show how they each keep diseases at arm’s length....

  11. Continuously variable focal length lens

    Science.gov (United States)

    Adams, Bernhard W; Chollet, Matthieu C

    2013-12-17

    A material preferably in crystal form having a low atomic number such as beryllium (Z=4) provides for the focusing of x-rays in a continuously variable manner. The material is provided with plural spaced curvilinear, optically matched slots and/or recesses through which an x-ray beam is directed. The focal length of the material may be decreased or increased by increasing or decreasing, respectively, the number of slots (or recesses) through which the x-ray beam is directed, while fine tuning of the focal length is accomplished by rotation of the material so as to change the path length of the x-ray beam through the aligned cylindrical slows. X-ray analysis of a fixed point in a solid material may be performed by scanning the energy of the x-ray beam while rotating the material to maintain the beam's focal point at a fixed point in the specimen undergoing analysis.

  12. CEBAF Upgrade Bunch Length Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Mahmoud [Old Dominion Univ., Norfolk, VA (United States)

    2016-05-01

    Many accelerators use short electron bunches and measuring the bunch length is important for efficient operations. CEBAF needs a suitable bunch length because bunches that are too long will result in beam interruption to the halls due to excessive energy spread and beam loss. In this work, bunch length is measured by invasive and non-invasive techniques at different beam energies. Two new measurement techniques have been commissioned; a harmonic cavity showed good results compared to expectations from simulation, and a real time interferometer is commissioned and first checkouts were performed. Three other techniques were used for measurements and comparison purposes without modifying the old procedures. Two of them can be used when the beam is not compressed longitudinally while the other one, the synchrotron light monitor, can be used with compressed or uncompressed beam.

  13. Experimental Assessment on the Flexural Bonding Performance of Concrete Beam with GFRP Reinforcing Bar under Repeated Loading

    Directory of Open Access Journals (Sweden)

    Minkwan Ju

    2015-01-01

    Full Text Available This study intends to investigate the flexural bond performance of glass fiber-reinforced polymer (GFRP reinforcing bar under repeated loading. The flexural bond tests reinforced with GFRP reinforcing bars were carried out according to the BS EN 12269-1 (2000 specification. The bond test consisted of three loading schemes: static, monotonic, and variable-amplitude loading to simulate ambient loading conditions. The empirical bond length based on the static test was 225 mm, whereas it was 317 mm according to ACI 440 1R-03. Each bond stress on the rib is released and bonding force is enhanced as the bond length is increased. Appropriate level of bond length may be recommended with this energy-based analysis. For the monotonic loading test, the bond strengths at pullout failure after 2,000,000 cycles were 10.4 MPa and 6.5 MPa, respectively: 63–70% of the values from the static loading test. The variable loading test indicated that the linear cumulative damage theory on GFRP bonding may not be appropriate for estimating the fatigue limit when subjected to variable-amplitude loading.

  14. 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.

  15. Fusion-bonded fluidic interconnects

    International Nuclear Information System (INIS)

    Fazal, I; Elwenspoek, M C

    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 discussed in terms of the homogeneity and strength of fusion bond. High pressure testing shows that the bond strength is large enough for most applications of fluidic interconnects. The bond strength for 525 µm thick silicon, with glass tubes having an outer diameter of 6 mm and with a wall thickness of 2 mm, is more than 60 bars after annealing at a temperature of 800 °C

  16. Sibling bereavement and continuing bonds.

    Science.gov (United States)

    Packman, Wendy; Horsley, Heidi; Davies, Betty; Kramer, Robin

    2006-11-01

    Historically, from a Freudian and medical model perspective, emotional disengagement from the deceased was seen as essential to the successful adaptation of bereavement. A major shift in the bereavement literature has occurred and it is now generally accepted that despite the permanence of physical separation, the bereaved remains involved and connected to the deceased and can be emotionally sustained through continuing bonds. The majority of literature has focused on adults and on the nature of continuing bonds following the death of a spouse. In this article, the authors demonstrate how the continuing bonds concept applies to the sibling relationship. We describe the unique continued relationship formed by bereaved children and adolescents following a sibling loss, highlight the factors that influence the siblings continuing bonds expressions, and offer clinical interventions. In our view, mental health professionals can play an important role in helping parents encourage activities that may facilitate the creation and maintenance of continuing bonds in their children.

  17. Continuous lengths of oxide superconductors

    Science.gov (United States)

    Kroeger, Donald M.; List, III, Frederick A.

    2000-01-01

    A layered oxide superconductor prepared by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon. A continuous length of a second substrate ribbon is overlaid on the first substrate ribbon. Sufficient pressure is applied to form a bound layered superconductor precursor powder between the first substrate ribbon and the second substrate ribbon. The layered superconductor precursor is then heat treated to establish the oxide superconducting phase. The layered oxide superconductor has a smooth interface between the substrate and the oxide superconductor.

  18. Summary of neutron scattering lengths

    International Nuclear Information System (INIS)

    Koester, L.

    1981-12-01

    All available neutron-nuclei scattering lengths are collected together with their error bars in a uniform way. Bound scattering lengths are given for the elements, the isotopes, and the various spin-states. They are discussed in the sense of their use as basic parameters for many investigations in the field of nuclear and solid state physics. The data bank is available on magnetic tape, too. Recommended values and a map of these data serve for an uncomplicated use of these quantities. (orig.)

  19. Overview of bunch length measurements

    International Nuclear Information System (INIS)

    Lumpkin, A. H.

    1999-01-01

    An overview of particle and photon beam bunch length measurements is presented in the context of free-electron laser (FEL) challenges. Particle-beam peak current is a critical factor in obtaining adequate FEL gain for both oscillators and self-amplified spontaneous emission (SASE) devices. Since measurement of charge is a standard measurement, the bunch length becomes the key issue for ultrashort bunches. Both time-domain and frequency-domain techniques are presented in the context of using electromagnetic radiation over eight orders of magnitude in wavelength. In addition, the measurement of microbunching in a micropulse is addressed

  20. Effect of different electrode tip angles with tilted torch in stationary gas tungsten arc welding: A 3D simulation

    International Nuclear Information System (INIS)

    Abid, M.; Parvez, S.; Nash, D.H.

    2013-01-01

    In this study, the effect of different tip angles (30°, 60°, 90° and 120°) on the arc and weld pool behavior is analyzed in 2 mm and 5 mm arc lengths with tilted (70°) torch. Arc temperature, velocity, current density, heat flux and gas shear are investigated in the arc region and pool convection and puddle shapes are studied in the weld pool region. The arc temperature at the tungsten electrode is found the maximum with sharp tip and decreases as the tip angle increases. The arc temperature on the anode (workpiece) surface becomes concentrated with increase in tip angle. The arc velocity and gas shear stress are observed large with sharp tip and decreasing as the tip angle increases. Current density on the anode surface does not change with tip angle and observed almost the same in all the tip angles in both 2 mm and 5 mm arc lengths. Heat flux due to conduction and convection is observed more sensitive to the tip angle and decreases as the tip angle increases. The electromagnetic force is slightly observed increasing and the buoyancy force is observed slightly decreasing with increase in tip angle. Analyzing each driving force in the weld pool individually shows that the gas drag and Marangoni forces are much stronger than the electromagnetic and buoyancy forces. The weld pool shape is observed wide and shallow in sharp and narrow and deep in large tip angle. Increasing the arc length does not change the weld pool width; however, the weld pool depth significantly changes with arc length and is observed deep in short arc length. The arc properties and weld pool shapes are observed wide ahead of the electrode tip in the weld direction due to 70° torch angle. Good agreement is observed between the numerical and experimental weld pool shapes

  1. Bonding techniques for flexural strengthening of R.C. beams using CFRP laminates

    Directory of Open Access Journals (Sweden)

    Alaa Morsy

    2013-09-01

    Full Text Available This paper presents an experimental study of an alternative method of attaching FRP laminates to reinforced concrete beams by the way of fasting steel rivets through the FRP laminate and concrete substrate. Five full scale R.C. beams were casted and strengthened in flexural using FRP laminate bonded with conventional epoxy and compared with other beams strengthened with FRP laminate and bonded with fastener “steel rivets” of 50 mm length and 10 mm diameter. Based on experimental evidence the beam strengthened with conventional bonding methods failed due to de-bonding with about 13% increase over the un-strengthened beam. On the other hand, the beams strengthened with FRP laminate and bonded by four steel fastener rivets only failed by de-bonding also but at higher flexural capacity with increase 19% over the un-strengthened beam.

  2. Structure phenomena in the bond zone of explosively bonded plates

    International Nuclear Information System (INIS)

    Livne, Z.

    1979-12-01

    In the bond areas of couples of explosively bonded plates, there are often zones, generally designated as ''molten pockets'', which have undergone melting and solidification. The object of the present study was to investigate molten pockets, which have a decisive effect on bond quality. The experimental samples for the study were chosen in consideration of the mutual behaviour of the plates constituting the couples, according to their equilibrium phase diagrams. To facilitate the investigation, large plates were bonded under conditions that enabled to to obtain wavy bond zones that included relatively large molten pockets. To clarify the complex nature of molten pockets and their surroundings, a wide variety of methods were employed. It was found that the shape and composition of molten pockets largely depend upon the mechanism of formation of both the bond wave and the molten pockets. It was also found that the composition of molten pockets is not homogeneous, which is manifest in the modification of the composition of the pockets, the solidification morphology, the phases, which have been identified by X-ray diffraction, and the bond strenght and hardness. Moreover, the different solidification morphologies revealed by metallography were found to depend upon the types of plates bonded, the bonding conditions and the location of pockets in the wavy interface. For molten pockets, cooling rates of 10 4 to 10 5 (degC/sec) have been deduced from interdendritic spacing, and found to be in good agreement with calculations after a mathematical model. It seems that the fast cooling rates and the steep temperature gradients are at the origin of the particular solidification phenomena observed in molten pockets

  3. 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.

  4. Making a robust carbon-cobalt(III) bond

    DEFF Research Database (Denmark)

    Larsen, Erik; Madsen, Anders Østergaard; Kofod, Pauli

    2009-01-01

    The coordination ion with a well-characterized carbon-cobalt(III) bond, the (1,4,7-triazacyclononane)(1,6-diamino-3-thia-4-hexanido)cobalt(III) dication, [Co(tacn)(C-aeaps)](2+) (aeaps, for aminoethylaminopropylsulfide), has been reacted with iodomethane, and the S-methyl thionium derivative has...... been isolated. The crystal structure of the resulting [Co(tacn)(C-aeaps-SCH(3))]Br(3) x 3 H(2)O at 122 K has been determined by X-ray diffraction techniques to verify the structure. The crystal structure determination shows that the carbon-cobalt bond length is even shorter (2.001(4) A) than in [Co......(tacn)(C-aeaps)](2+) participates in bonding to cobalt(III), having implications for the transformation between the carbon- and sulfur-bound forms of the aeaps ligand....

  5. Diet, nutrition and telomere length.

    Science.gov (United States)

    Paul, Ligi

    2011-10-01

    The ends of human chromosomes are protected by DNA-protein complexes termed telomeres, which prevent the chromosomes from fusing with each other and from being recognized as a double-strand break by DNA repair proteins. Due to the incomplete replication of linear chromosomes by DNA polymerase, telomeric DNA shortens with repeated cell divisions until the telomeres reach a critical length, at which point the cells enter senescence. Telomere length is an indicator of biological aging, and dysfunction of telomeres is linked to age-related pathologies like cardiovascular disease, Parkinson disease, Alzheimer disease and cancer. Telomere length has been shown to be positively associated with nutritional status in human and animal studies. Various nutrients influence telomere length potentially through mechanisms that reflect their role in cellular functions including inflammation, oxidative stress, DNA integrity, DNA methylation and activity of telomerase, the enzyme that adds the telomeric repeats to the ends of the newly synthesized DNA. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Tube Length and Water Flow

    Directory of Open Access Journals (Sweden)

    Ben Ruktantichoke

    2011-06-01

    Full Text Available In this study water flowed through a straight horizontal plastic tube placed at the bottom of a large tank of water. The effect of changing the length of tubing on the velocity of flow was investigated. It was found that the Hagen-Poiseuille Equation is valid when the effect of water entering the tube is accounted for.

  7. Finite length Taylor Couette flow

    Science.gov (United States)

    Streett, C. L.; Hussaini, M. Y.

    1987-01-01

    Axisymmetric numerical solutions of the unsteady Navier-Stokes equations for flow between concentric rotating cylinders of finite length are obtained by a spectral collocation method. These representative results pertain to two-cell/one-cell exchange process, and are compared with recent experiments.

  8. Fragility and cooperativity concepts in hydrogen-bonded organic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Delpouve, N., E-mail: delpouve.nicolas@gmail.com [AMME-LECAP EA 4528 International Laboratory, University of Rouen, Avenue de l' Universite BP 12, 76801 Saint Etienne du Rouvray (France); Vuillequez, A.; Saiter, A.; Youssef, B.; Saiter, J.M. [AMME-LECAP EA 4528 International Laboratory, University of Rouen, Avenue de l' Universite BP 12, 76801 Saint Etienne du Rouvray (France)

    2012-09-01

    Molecular dynamics at the glass transition of three lactose/oil glassy systems have been investigated according to the cooperativity and fragility approaches. From Donth's approach, the cooperativity length is estimated by modulated temperature calorimetric measurements. Results reveal that modification of the disaccharide by oil leads to increase the disorder degree in the lactose, the size of the cooperative domains and the fragility index. These particular hydrogen-bonded organic glasses follow the general tendency observed on organic and inorganic polymers: the higher the cooperativity length, the higher the value of the fragility index at T{sub g}.

  9. Fragility and cooperativity concepts in hydrogen-bonded organic glasses

    International Nuclear Information System (INIS)

    Delpouve, N.; Vuillequez, A.; Saiter, A.; Youssef, B.; Saiter, J.M.

    2012-01-01

    Molecular dynamics at the glass transition of three lactose/oil glassy systems have been investigated according to the cooperativity and fragility approaches. From Donth's approach, the cooperativity length is estimated by modulated temperature calorimetric measurements. Results reveal that modification of the disaccharide by oil leads to increase the disorder degree in the lactose, the size of the cooperative domains and the fragility index. These particular hydrogen-bonded organic glasses follow the general tendency observed on organic and inorganic polymers: the higher the cooperativity length, the higher the value of the fragility index at T g .

  10. Small angle scattering and polymers

    International Nuclear Information System (INIS)

    Cotton, J.P.

    1996-01-01

    The determination of polymer structure is a problem of interest for both statistical physics and industrial applications. The average polymer structure is defined. Then, it is shown why small angle scattering, associated with isotopic substitution, is very well suited to the measurement of the chain conformation. The corresponding example is the old, but pedagogic, measurement of the chain form factor in the polymer melt. The powerful contrast variation method is illustrated by a recent determination of the concentration profile of a polymer interface. (author) 12 figs., 48 refs

  11. Low-Cost High-Efficiency Solar Cells with Wafer Bonding and Plasmonic Technologies

    Science.gov (United States)

    Tanake, Katsuaki

    InP/Si substrates for bulk InP in the fabrication of such a four-junction solar cell could significantly reduce the substrate cost since the current prices for commercial InP substrates are much higher than those for Si substrates by two orders of magnitude. Direct heteroepitaxial growth of InP thin films on Si substrates has not produced the low dislocation-density high quality layers required for active InGaAs/InP in optoelectronic devices due to the ˜8% lattice mismatch between InP and Si. We successfully fabricated InP/Si substrates by He implantation of InP prior to bonding to a thermally oxidized Si substrate and annealing to exfoliate an InP thin film. The thickness of the exfoliated InP films was only 900 nm, which means hundreds of the InP/Si substrates could be prepared from a single InP wafer in principle. The photovoltaic current-voltage characteristics of the In0.53Ga0.47As cells fabricated on the wafer-bonded InP/Si substrates were comparable to those synthesized on commercially available epi-ready InP substrates, and had a ˜20% higher short-circuit current which we attribute to the high reflectivity of the InP/SiO2/Si bonding interface. This work provides an initial demonstration of wafer-bonded InP/Si substrates as an alternative to bulk InP substrates for solar cell applications. We have observed photocurrent enhancements up to 260% at 900 nm for a GaAs cell with a dense array of Ag nanoparticles with 150 nm diameter and 20 nm height deposited through porous alumina membranes by thermal evaporation on top of the cell, relative to reference GaAs cells with no metal nanoparticle array. This dramatic photocurrent enhancement is attributed to the effect of metal nanoparticles to scatter the incident light into photovoltaic layers with a wide range of angles to increase the optical path length in the absorber layer. GaAs solar cells with metallic structures at the bottom of the photovoltaic active layers, not only at the top, using semiconductor

  12. How Is the Enamel Affected by Different Orthodontic Bonding Agents and Polishing Techniques?

    Science.gov (United States)

    Heravi, Farzin; Shafaee, Hooman; Abdollahi, Mojtaba; Rashed, Roozbeh

    2015-03-01

    The objective of this study was to assess the effect of new bonding techniques on enamel surface. Sixty upper central incisors were randomly divided into two equal groups. In the first group, metal brackets were bonded using TransbondXT and, in the second group, the same brackets were bonded with Maxcem Elite. The shear bond strength (SBS) of both agents to enamel was measured and the number and length of enamel cracks before bonding, after debonding and after polishing were compared. The number of visible cracks and the adhesive remnant index (ARI) scores in each group were also measured. There were significantly more enamel cracks in the Transbond XT group after debonding and polishing compared to the Maxcem Elite group. There was no significant difference in the length of enamel cracks between the two groups; but, in each group, a significant increase in the length of enamel cracks was noticeable after debonding. Polishing did not cause any statistically significant change in crack length. The SBS of Maxcem Elite was significantly lower than that of Transbond XT (95% confidence interval). Maxcem Elite offers clinically acceptable bond strength and can thus be used as a routine adhesive for orthodontic purposes since it is less likely to damage the enamel.

  13. Theoretical study of ZnO adsorption and bonding on Al2O3 (0001) surface

    Institute of Scientific and Technical Information of China (English)

    LI Yanrong; YANG Chun; XUE Weidong; LI Jinshan; LIU Yonghua

    2004-01-01

    ZnO adsorption on sapphire (0001) surface is theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on ab initio molecular dynamics. The results reveal that the surface relaxation in the first layer Al-O is reduced, even eliminated after the surface adsorption of ZnO, and the chemical bonding energy is 434.3(±38.6) kJ·mol-1. The chemical bond of ZnO (0.185 ± 0.01 nm) has a 30° angle away from the adjacent Al-O bond, and the stable chemical adsorption position of the Zn is deflected from the surface O-hexagonal symmetry with an angle of about 30°. The analysis of the atomic populations, density of state and bonding electronic density before and after the adsorption indicates that the chemical bond formed by the O2- of the ZnO and the surface Al3+ has a strong ionic bonding characteristic, while the chemical bond formed by the Zn2+ and the surface O2- has an obvious covalent characteristic, which comes mainly from the hybridization of the Zn 4s and the O 2p and partially from that of the Zn 3d and the O 2p.

  14. A Study of Bond of Structural Timber and Carbon Fiber Reinforced Polymer Plate

    Directory of Open Access Journals (Sweden)

    Yongtaeg LEE

    2015-11-01

    Full Text Available The increase of well-being culture of problem related to environmental depletion of resource is not the growing interest in timber the natural material of construction markets. Also, the perception for historic preservation has been increased in respond to heightened interest. However, it is fairly difficult for architectural properties to maintain their durability because it was made by timber construction. Preventing traditional structure from damage and structural performance reduction is paramount in maintenance problem. A number of studies of reinforced method have been conducted in order to solve such a problem. In this paper, external bonded reinforcement and near-surface mounted was used as a way to reinforce timber structure’s durability. Bond strength for specimens with different bond length was investigated. As a result showed, maximum bond strength in bond length 300 mm from all method, was found to be not increased of bond strength over the certain bond length.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9702

  15. Occurrence of protein disulfide bonds in different domains of life: a comparison of proteins from the Protein Data Bank.

    Science.gov (United States)

    Bošnjak, I; Bojović, V; Šegvić-Bubić, T; Bielen, A

    2014-03-01

    Disulfide bonds (SS bonds) are important post-translational modifications of proteins. They stabilize a three-dimensional (3D) structure (structural SS bonds) and also have the catalytic or regulatory functions (redox-active SS bonds). Although SS bonds are present in all groups of organisms, no comparative analyses of their frequency in proteins from different domains of life have been made to date. Using the Protein Data Bank, the number and subcellular locations of SS bonds in Archaea, Bacteria and Eukarya have been compared. Approximately three times higher frequency of proteins with SS bonds in eukaryotic secretory organelles (e.g. endoplasmic reticulum) than in bacterial periplasmic/secretory pathways was calculated. Protein length also affects the SS bond frequency: the average number of SS bonds is positively correlated with the length for longer proteins (>200 amino acids), while for the shorter and less stable proteins (proteins (250-350 amino acids) indicated a high number of SS bonds only in Archaea which could be explained by the need for additional protein stabilization in hyperthermophiles. The results emphasize higher capacity for the SS bond formation and isomerization in Eukarya when compared with Archaea and Bacteria.

  16. Relativistic contributions to the bonding in Cu2

    International Nuclear Information System (INIS)

    Martin, R.L.

    1983-01-01

    The influence of relativity on the spectroscopic parameters of Cu 2 has been investigated by evaluating the mass-velocity and one electron Darwin terms of the Breit--Pauli Hamiltonian in the first order of perturbation theory. The relativistic corrections are of the order of 10% of the SCF and GVB results and result in a deeper (approx.1.5 kcal), stiffer (approx.15 cm - 1 ) well, with the bond length contracted by about 0.1a 0

  17. TDDFT study on intramolecular hydrogen bond of photoexcited methyl salicylate.

    Science.gov (United States)

    Qu, Peng; Tian, Dongxu

    2014-01-01

    The equilibrium geometries, IR-spectra and transition mechanism of intramolecular hydrogen-bonded methyl salicylate in excited state were studied using DFT and TDDFT with 6-31++G (d, p) basis set. The length of hydrogen bond OH⋯OC is decreased from 1.73 Å in the ground state to 1.41 and 1.69 Å in the excited S1 and S3 states. The increase of bond length for HO and CO group also indicates that in excited state the hydrogen bond OH⋯OC is strengthened. IR spectra show HO and CO stretching bands are strongly redshifted by 1387 and 67 cm(-1) in the excited S1 and S3 states comparing to the ground state. The excitation energy and the absorption spectrum show the S3 state is the main excited state of the low-lying excited states. By analyzing the frontier molecular orbitals, the transition from the ground state to the excited S1 and S3 states was predicted to be the π→π∗ mode. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. 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...... of the cross rolled volume fraction is found. To further asses this effect, and the anisotropy, it is necessary to acquire knowledge about both texture and microstructure, e.g. by TEM. Roll bonding of pre-strained aluminium is found to be a possible alternative to ARB in the quest for ultra-fine grained...

  19. 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.

  20. An Angle Criterion for Riesz Bases

    DEFF Research Database (Denmark)

    Lindner, Alexander M; Bittner, B.

    1999-01-01

    We present a characterization of Riesz bases in terms ofthe angles between certain finite dimensional subspaces. Correlationsbetween the bounds of the Riesz basis and the size of the angles arederived....

  1. Interference in a thick plate at large angle of incidence

    International Nuclear Information System (INIS)

    Tavassoli, M.T.; Shah Shehany, F.

    1991-01-01

    A new approach to the interference in a plane parallel plate is introduced which is valid for any angle of incidence and any thickness. It is shown that the interference in a plate can be interpreted as the interference in a double-slit and the corresponding parameters are derived. It is also shown that for a particular angle of incidence, which depends only on the refractive index, the interfringes are minimum. It is proved theoretically and verified experimentally that the interference around this particular angle of incidence has several exploitable features which include: a) In thick plates large numbers of equidistant fringes are formed which are very adequate for producing interference gratings. b) It provides, in comparison to the conventional interferometric methods, an easier and more accurate means for direct measurement of wave-length. c) Multiple-beam interference at this particular angle improve the accuracy of the measurement of the fine structures of the atomic spectra, compared to other interferometric methods. (author). 4 refs, 4 figs

  2. Incident angle dependence of reactions between graphene and hydrogen atom by molecular dynamics simulation

    International Nuclear Information System (INIS)

    Saito, Seiki; Nakamura, Hiroaki; Ito, Atsushi

    2010-01-01

    Incident angle dependence of reactions between graphene and hydrogen atoms are obtained qualitatively by classical molecular dynamics simulation under the NVE condition with modified Brenner reactive empirical bond order (REBO) potential. Chemical reaction depends on two parameters, i.e., polar angle θ and azimuthal angle φ of the incident hydrogen. From the simulation results, it is found that the reaction rates strongly depend on polar angle θ. Reflection rate becomes larger with increasing θ, and the θ dependence of adsorption rate is also found. The θ dependence is caused by three dimensional structure of the small potential barrier which covers adsorption sites. φ dependence of penetration rate is also found for large θ. (author)

  3. Design and Pitch Angle Optimisation of Horizontal Axis Hydrokinetic Turbine with Constant Tip Speed Ratio

    Directory of Open Access Journals (Sweden)

    Nigam Suyash

    2017-01-01

    Full Text Available Booming population and associated energy demands, looming threat of exhaustion of conventional sources of energy and the severe environmental repercussions of the same call for alternate sources of clean energy. Hydrokinetic turbine is one such developing technology which harnesses zero-head free flow of water and affects hydrological ecology minimally. This paper discusses the optimisation of Horizontal Axis Hydrokinetic Turbine (HAHkT blade chord length and twist angle using blade element momentum (BEM theory to achieve a constant optimal angle of attack (AoA, thus maximising the power output. To achieve this while maintaining robustness at the hub end and eliminate cavitation, two different hydrofoils (S832 and E817 are selected. S832 is simulated using ANSYS 14.0 at low (00 and high (150 angles of attack and compared against more widely used NACA 4412 to study flow separation characteristics. This is followed by calculating angles of relative flow, ratios of chord length and subsequently twist angles for each blade element using MATLAB simulations. A blade model is thus developed for visualisation using computer aided designing after obtaining optimal chord lengths and pitch angles.

  4. 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.

  5. Ultrashort Channel Length Black Phosphorus Field-Effect Transistors.

    Science.gov (United States)

    Miao, Jinshui; Zhang, Suoming; Cai, Le; Scherr, Martin; Wang, Chuan

    2015-09-22

    This paper reports high-performance top-gated black phosphorus (BP) field-effect transistors with channel lengths down to 20 nm fabricated using a facile angle evaporation process. By controlling the evaporation angle, the channel length of the transistors can be reproducibly controlled to be anywhere between 20 and 70 nm. The as-fabricated 20 nm top-gated BP transistors exhibit respectable on-state current (174 μA/μm) and transconductance (70 μS/μm) at a VDS of 0.1 V. Due to the use of two-dimensional BP as the channel material, the transistors exhibit relatively small short channel effects, preserving a decent on-off current ratio of 10(2) even at an extremely small channel length of 20 nm. Additionally, unlike the unencapsulated BP devices, which are known to be chemically unstable in ambient conditions, the top-gated BP transistors passivated by the Al2O3 gate dielectric layer remain stable without noticeable degradation in device performance after being stored in ambient conditions for more than 1 week. This work demonstrates the great promise of atomically thin BP for applications in ultimately scaled transistors.

  6. Orbital Exponent Optimization in Elementary VB Calculations of the Chemical Bond in the Ground State of Simple Molecular Systems

    Science.gov (United States)

    Magnasco, Valerio

    2008-01-01

    Orbital exponent optimization in the elementary ab-initio VB calculation of the ground states of H[subscript 2][superscript +], H[subscript 2], He[subscript 2][superscript +], He[subscript 2] gives a fair description of the exchange-overlap component of the interatomic interaction that is important in the bond region. Correct bond lengths and…

  7. Length of a Hanging Cable

    Directory of Open Access Journals (Sweden)

    Eric Costello

    2011-01-01

    Full Text Available The shape of a cable hanging under its own weight and uniform horizontal tension between two power poles is a catenary. The catenary is a curve which has an equation defined by a hyperbolic cosine function and a scaling factor. The scaling factor for power cables hanging under their own weight is equal to the horizontal tension on the cable divided by the weight of the cable. Both of these values are unknown for this problem. Newton's method was used to approximate the scaling factor and the arc length function to determine the length of the cable. A script was written using the Python programming language in order to quickly perform several iterations of Newton's method to get a good approximation for the scaling factor.

  8. Minimal Length, Measurability and Gravity

    Directory of Open Access Journals (Sweden)

    Alexander Shalyt-Margolin

    2016-03-01

    Full Text Available The present work is a continuation of the previous papers written by the author on the subject. In terms of the measurability (or measurable quantities notion introduced in a minimal length theory, first the consideration is given to a quantum theory in the momentum representation. The same terms are used to consider the Markov gravity model that here illustrates the general approach to studies of gravity in terms of measurable quantities.

  9. πK-scattering lengths

    International Nuclear Information System (INIS)

    Volkov, M.K.; Osipov, A.A.

    1983-01-01

    The msub(π)asub(0)sup(1/2)=0.1, msub(π)asub(0)sup(3/2)=-0.1, msub(π)asub(0)sup((-))=0.07, msub(π)sup(3)asub(1)sup(1/2)=0.018, msub(π)sup(3)asub(1)aup(3/2)=0.002, msub(π)sup(3)asub(1)sup((-))=0.0044, msub(π)sup(5)asub(2)sup(1/2)=2.4x10sup(-4) and msub(π)sup(5)asub(2)sup(3/2)=-1.2x10sup(-4) scattering lengths are calculated in the framework of the composite meson model which is based on four-quark interaction. The decay form factors of (rho, epsilon, S*) → 2π, (K tilde, K*) → Kπ are used. The q 2 -terms of the quark box diagrams are taken into account. It is shown that the q 2 -terms of the box diagrams give the main contribution to the s-wave scattering lengths. The diagrams with the intermediate vector mesons begin to play the essential role at calculation of the p- and d-wave scattering lengths

  10. dimensional architectures via hydrogen bonds

    Indian Academy of Sciences (India)

    Administrator

    organization and has potential applications in the field of magnetism ... The concepts of crystal engineering ... 4. However, the utilization of hydrogen bond supramolecular syn- ... sembling the coordination networks by designing the ligands ...

  11. 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...

  12. 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.

  13. Method to improve commercial bonded SOI material

    Science.gov (United States)

    Maris, Humphrey John; Sadana, Devendra Kumar

    2000-07-11

    A method of improving the bonding characteristics of a previously bonded silicon on insulator (SOI) structure is provided. The improvement in the bonding characteristics is achieved in the present invention by, optionally, forming an oxide cap layer on the silicon surface of the bonded SOI structure and then annealing either the uncapped or oxide capped structure in a slightly oxidizing ambient at temperatures greater than 1200.degree. C. Also provided herein is a method for detecting the bonding characteristics of previously bonded SOI structures. According to this aspect of the present invention, a pico-second laser pulse technique is employed to determine the bonding imperfections of previously bonded SOI structures.

  14. Method of bonding

    International Nuclear Information System (INIS)

    Saller, H.A.; Hodge, E.S.; Paprocki, S.J.; Dayton, R.W.

    1987-01-01

    A method of making a fuel-containing structure for nuclear reactors is described comprising providing an assembly comprising fuel units consisting of a core plate containing thermal-neutron-fissionable material, sheets of cladding metal on its bottom and top surfaces, the cladding sheets being of greater width and length than the core plates whereby recesses are formed at the ends and sides of the core plate, and end pieces and first side pieces of cladding metal of the same thickness as the core plate positioned in the recesses. The assembly further comprises second side pieces of cladding metal engaging the cladding sheets so as to space the fuel units from one another, and filler plates of an acid-dissolvable nonresilient material whose melting point is above 2000 0 F, arranged between a pair of the second side pieces and the cladding plates of two adjacent fuel units. The filler plates have the same thickness as the second side pieces. The method further comprises enclosing the entire assembly in an envelope; evacuating the interior of the entire assembly through the envelope; applying inert gas under a pressure of about 10,000 psi to the outside of the envelope while at the same time heating the assembly to a temperature above the flow point of the cladding metal but below the melting point of any material of the assembly, slowly cooling the assembly to room temperature; removing the envelope; and dissolving the filler plates without attacking the cladding metal

  15. Modification of the Gurney Equation for Explosive Bonding by Slanted Elevation Angle

    Science.gov (United States)

    2014-04-01

    weld metal solidification cracking in steels and stainless steels . He has also undertaken extensive work on improving the weld zone toughness of high...welded aluminium–dual phase steel ’, Mater Lett, vol 62(25), 2008, p4158-4160. [8] A. Durgutlu, B. Gulenc, F. Findik, ‘Examination of copper/ stainless ...and utilising an explosive charge with supersonic detonation velocity. Two joint combinations were produced with superaustenitic steel as the flyer

  16. Effect of quantum nuclear motion on hydrogen bonding

    Science.gov (United States)

    McKenzie, Ross H.; Bekker, Christiaan; Athokpam, Bijyalaxmi; Ramesh, Sai G.

    2014-05-01

    This work considers how the properties of hydrogen bonded complexes, X-H⋯Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O-H⋯O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4 - 3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X-H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends.

  17. Effect of quantum nuclear motion on hydrogen bonding

    International Nuclear Information System (INIS)

    McKenzie, Ross H.; Bekker, Christiaan; Athokpam, Bijyalaxmi; Ramesh, Sai G.

    2014-01-01

    This work considers how the properties of hydrogen bonded complexes, X–H⋯Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O–H⋯O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4 − 3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X–H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends

  18. Electro-optical parameters of bond polarizability model for aluminosilicates.

    Science.gov (United States)

    Smirnov, Konstantin S; Bougeard, Daniel; Tandon, Poonam

    2006-04-06

    Electro-optical parameters (EOPs) of bond polarizability model (BPM) for aluminosilicate structures were derived from quantum-chemical DFT calculations of molecular models. The tensor of molecular polarizability and the derivatives of the tensor with respect to the bond length are well reproduced with the BPM, and the EOPs obtained are in a fair agreement with available experimental data. The parameters derived were found to be transferable to larger molecules. This finding suggests that the procedure used can be applied to systems with partially ionic chemical bonds. The transferability of the parameters to periodic systems was tested in molecular dynamics simulation of the polarized Raman spectra of alpha-quartz. It appeared that the molecular Si-O bond EOPs failed to reproduce the intensity of peaks in the spectra. This limitation is due to large values of the longitudinal components of the bond polarizability and its derivative found in the molecular calculations as compared to those obtained from periodic DFT calculations of crystalline silica polymorphs by Umari et al. (Phys. Rev. B 2001, 63, 094305). It is supposed that the electric field of the solid is responsible for the difference of the parameters. Nevertheless, the EOPs obtained can be used as an initial set of parameters for calculations of polarizability related characteristics of relevant systems in the framework of BPM.

  19. Widening of the femoral proximal diaphysis--metaphysis angle in fetuses with achondroplasia.

    Science.gov (United States)

    Khalil, A; Morales-Roselló, J; Morlando, M; Bhide, A; Papageorghiou, A; Thilaganathan, B

    2014-07-01

    It has recently been reported that fetuses with achondroplasia have a wider than expected femoral proximal diaphysis-metaphysis angle (femoral angle). The aim of this case-control study was to investigate this finding. Cases with confirmed achondroplasia (n = 6), small-for-gestational-age fetuses (n = 70) and a group of normal fetuses (n = 377) were included in this study. The ultrasound image of the femur was examined by two independent experienced observers blinded to the diagnosis, who measured the femoral angle. These values were converted into multiples of the expected median (MoM), after adjustment for gestational age and femur length. Prevalence of various prenatal ultrasound signs of achondroplasia was determined in affected fetuses. Intra- and interobserver agreement of measurement of femoral angle was assessed using 95% limits of agreement and kappa statistics. The femoral angle can be measured accurately by ultrasound, and increases with both increasing gestational age and increasing femur length. The femoral angle-MoM was significantly higher in fetuses with achondroplasia than in the control group (1.36 vs 1.00 MoM, P achondroplasia (83.3%), which was the most consistent finding other than shortening of the long bones. The femoral angle is wider in fetuses with achondroplasia. This new ultrasound sign appears promising as an additional discriminatory marker when clinicians are faced with a case of short long bones in the third trimester. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.

  20. Comparative evaluation of shear bond strength of metallic brackets bonded with two different bonding agents under dry conditions and with saliva contamination

    Directory of Open Access Journals (Sweden)

    Mashallah Khanehmasjedi

    2017-02-01

    Conclusion: Application of Single Bond and Assure bonding agents resulted in adequate bond strength of brackets to tooth structures. Contamination with saliva significantly decreased the bond strength of Assure bonding agent compared with dry conditions.

  1. 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. ​: A im: 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.

  2. A facile route for irreversible bonding of plastic-PDMS hybrid microdevices at room temperature.

    Science.gov (United States)

    Tang, Linzhi; Lee, Nae Yoon

    2010-05-21

    Plastic materials do not generally form irreversible bonds with poly(dimethylsiloxane) (PDMS) regardless of oxygen plasma treatment and a subsequent thermal process. In this paper, we perform plastic-PDMS bonding at room temperature, mediated by the formation of a chemically robust amine-epoxy bond at the interfaces. Various plastic materials, such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polyimide (PI), and poly(ethylene terephthalate) (PET) were adopted as choices for plastic materials. Irrespective of the plastic materials used, the surfaces were successfully modified with amine and epoxy functionalities, confirmed by the surface characterizations such as water contact angle measurements and X-ray photoelectron spectroscopy (XPS), and chemically robust and irreversible bonding was successfully achieved within 1 h at room temperature. The bonding strengths of PDMS with PMMA and PC sheets were measured to be 180 and 178 kPa, respectively, and their assemblies containing microchannel structures endured up to 74 and 84 psi (510 and 579 kPa) of introduced compressed air, respectively, without destroying the microdevices, representing a robust and highly stable interfacial bonding. In addition to microchannel-molded PDMS bonded with flat plastic substrates, microchannel-embossed plastics were also bonded with a flat PDMS sheet, and both types of bonded assemblies displayed sufficiently robust bonding, tolerating an intense influx of liquid whose per-minute injection volume was nearly 1000 to 2000 times higher than the total internal volume of the microchannel used. In addition to observing the bonding performance, we also investigated the potential of surface amine and epoxy functionalities as durable chemical adhesives by observing their storage-time-dependent bonding performances.

  3. The Small angle TIle Calorimeter project in DELPHI

    International Nuclear Information System (INIS)

    Alvsvaag, S.J.; Maeland, O.A.; Klovning, A.

    1995-01-01

    The new Small Angle TIle Calorimeter (STIC) covers the forward regions in DELPHI. The main motivation for its construction was to achieve a systematic error of 0.1% on the luminosity determination. This detector consists of a ''shashlik'' type calorimeter, equipped with two planes of silicon pad detectors placed respectively after 4 and 7.4 radiation lengths. A veto counter, composed of two scintillator planes, covers the front of the calorimeter to allow e-γ separation and to provide a neutral energy trigger.The physics motivations for this project, results from extensive testbeam measurements and the performance during the 1994 LEP run are reported here. (orig.)

  4. GALAXI: Gallium anode low-angle x-ray instrument

    Directory of Open Access Journals (Sweden)

    Emmanuel Kentzinger

    2016-03-01

    Full Text Available The high brilliance laboratory small angle X-ray scattering instrument GALAXI, which is operated by JCNS, Forschungszentrum Jülich, permits the investigation of chemical correlations in bulk materials or of structures deposited on a surface at nanometre and mesoscopic length scales. The instrument is capable to perform GISAXS experiments in reflection at grazing incidence as well as SAXS experiments in transmission geometry. The X-ray flux on sample is comparable or higher than the one obtained at a comparable beamline at a second generation synchrotron radiation source.

  5. Voltage-assisted polymer wafer bonding

    International Nuclear Information System (INIS)

    Varsanik, J S; Bernstein, J J

    2012-01-01

    Polymer wafer bonding is a widely used process for fabrication of microfluidic devices. However, best practices for polymer bonds do not achieve sufficient bond strength for many applications. By applying a voltage to a polymer bond in a process called voltage-assisted bonding, bond strength is shown to improve dramatically for two polymers (Cytop™ and poly(methyl methacrylate)). Several experiments were performed to provide a starting point for further exploration of this technique. An optimal voltage range is experimentally observed with a reduction in bonding strength at higher voltages. Additionally, voltage-assisted bonding is shown to reduce void diameter due to bond defects. An electrostatic force model is proposed to explain the improved bond characteristics. This process can be used to improve bond strength for most polymers. (paper)

  6. 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...

  7. The Q-angle and sport

    DEFF Research Database (Denmark)

    Hahn, Thomas; Foldspang, Anders

    1997-01-01

    Quadriceps muscle contraction tends to straighten the Q angle. We expected that sports comprising a high amount of quadriceps training could be associated with low Q angles. The aim of the present study was to estimate the Q angle in athletes and to investigate its potential associations with par......Quadriceps muscle contraction tends to straighten the Q angle. We expected that sports comprising a high amount of quadriceps training could be associated with low Q angles. The aim of the present study was to estimate the Q angle in athletes and to investigate its potential associations...... with participation in sport. Three hundred and thirty-nine athletes had their Q angle measured. The mean of right-side Q angles was higher than left side, and the mean Q angle was higher in women than in men. The Q angle was positively associated with years of jogging, and negatively with years of soccer, swimming...... and sports participation at all. It is concluded that the use of Q angle measurements is questionable....

  8. Wafer scale oblique angle plasma etching

    Science.gov (United States)

    Burckel, David Bruce; Jarecki, Jr., Robert L.; Finnegan, Patrick Sean

    2017-05-23

    Wafer scale oblique angle etching of a semiconductor substrate is performed in a conventional plasma etch chamber by using a fixture that supports a multiple number of separate Faraday cages. Each cage is formed to include an angled grid surface and is positioned such that it will be positioned over a separate one of the die locations on the wafer surface when the fixture is placed over the wafer. The presence of the Faraday cages influences the local electric field surrounding each wafer die, re-shaping the local field to be disposed in alignment with the angled grid surface. The re-shaped plasma causes the reactive ions to follow a linear trajectory through the plasma sheath and angled grid surface, ultimately impinging the wafer surface at an angle. The selected geometry of the Faraday cage angled grid surface thus determines the angle at with the reactive ions will impinge the wafer.

  9. Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure

    Directory of Open Access Journals (Sweden)

    Harsha L Rao

    2012-01-01

    Full Text Available Background: Blotchy pigments in the anterior chamber (AC angle are considered diagnostic of primary angle closure (PAC. But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects, above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3 and in open angles was 4.7% (95% CI, 3.2-6.3. Blotchy pigments were more frequently seen in inferior (16% and superior quadrants (15% of occludable angles, and inferior quadrant of open angles (4%. Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1. Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments.

  10. Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure

    Science.gov (United States)

    Rao, Harsha L; Mungale, Sachin C; Kumbar, Tukaram; Parikh, Rajul S; Garudadri, Chandra S

    2012-01-01

    Background: Blotchy pigments in the anterior chamber (AC) angle are considered diagnostic of primary angle closure (PAC). But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON) in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects), above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3) and in open angles was 4.7% (95% CI, 3.2-6.3). Blotchy pigments were more frequently seen in inferior (16%) and superior quadrants (15%) of occludable angles, and inferior quadrant of open angles (4%). Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1). Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments. PMID:23202393

  11. Small-angle neutron scattering instrument at MINT

    International Nuclear Information System (INIS)

    Mohd Ali Sufi; Yusof Abdullah; Razali Kassim; Hamid; Shahidan Radiman; Mohammad Deraman; Abdul Ghaffar Ramli

    1996-01-01

    The Small Angle Neutron Scattering (SANS) Instrument has been developed at Malaysian Institute for Nuclear Technology Research (MINT) for studying structural properties of materials on the length scale 1 nm to 100 nm. This is the length scale which is relevant for many topics within soft condensed matter, like polymers, colloids, biological macromolecules, etc. The SANS is a complementary technique to X-ray and electron scattering. However, while these later techniques give information on structures near surface, SANS concerns the structure of the bulk. Samples studied by SANS technique are typically bulk materials of the sizes mm's to cm's, or materials dissolved in a liquid. This paper described the general characteristics of SANS instrument as well as the experimental formulation in neutron scattering. The preliminary results obtained by this instrument are shown

  12. Ray-tracing studies for a whole-viewing-angle retroreflector

    International Nuclear Information System (INIS)

    Yang, B.; Friedsam, H.

    2000-01-01

    The APS Survey and Alignment team uses LEICA laser trackers for the majority of their alignment tasks. These instruments utilize several different retroreflectors for tracking the path of the laser interferometer. Currently in use are open-air corner cubes with an acceptance angle of ±20 degree, corner cube prisms with an acceptance angle of ±50degree, and a Cat's eye with an acceptance angle of ±60degree. Best measurement results can be achieved by using an open-air corner cube that eliminates the need for the laser beam to travel through a different medium before it returns to the instrument detector. However, the trade off is a small acceptance angle. In order to overcome the limitations of the small acceptance angles, Takatsuji et al. has proposed the creation of a full-viewing-angle retroreflector. Based on the notion that the radius R 1 of a common Cat's eye is proportional to R 2 , one can write: R 1 = (n minus 1)R 2 . In the case that n, the refractive index of glass, equals 2, the radii R 1 and R 2 are identical, and one can create a solid sphere Cat's eye. This design has the advantages that no adhesives are used to bond the two hemispheres together, misalignments between the hemispheres are not an issue, and most importantly, larger acceptance angles are possible. This paper shows the results of their ray tracing calculations characterizing the geometrical optics

  13. Structure and weak hydrogen bonds in liquid acetaldehyde

    Directory of Open Access Journals (Sweden)

    Cordeiro Maria A. M.

    2004-01-01

    Full Text Available Monte Carlo simulations have been performed to investigate the structure and hydrogen bonds formation in liquid acetaldehyde. An all atom model for the acetaldehyde have been optimized in the present work. Theoretical values obtained for heat of vaporisation and density of the liquid are in good agreement with experimental data. Graphics of radial distribution function indicate a well structured liquid compared to other similar dipolar organic liquids. Molecular mechanics minimization in gas phase leads to a trimer of very stable structure. The geometry of this complex is in very good agreement with the rdf. The shortest site-site correlation is between oxygen and the carbonyl hydrogen, suggesting that this correlation play a important role in the liquid structure and properties. The OxxxH average distance and the C-HxxxO angle obtained are characteristic of weak hydrogen bonds.

  14. Hydrogen bonded networks in formamide [HCONH2]n (n = 1 – 10 ...

    Indian Academy of Sciences (India)

    gns

    Table S1: Comparison of interaction energy (I.E) in kcal/mol in four arrangements of formamide n=1-10 at B3LYP/D95** level of theory. n = #monomers. Table S2: O---H bond length (in Å) for formamide clusters n = (2-10). Table S3: N-H bond stretching frequency (in cm-1) for four arrangements of formamide clusters n.

  15. Measurement of Capillary Radius and Contact Angle within Porous Media.

    Science.gov (United States)

    Ravi, Saitej; Dharmarajan, Ramanathan; Moghaddam, Saeed

    2015-12-01

    The pore radius (i.e., capillary radius) and contact angle determine the capillary pressure generated in a porous medium. The most common method to determine these two parameters is through measurement of the capillary pressure generated by a reference liquid (i.e., a liquid with near-zero contact angle) and a test liquid. The rate of rise technique, commonly used to determine the capillary pressure, results in significant uncertainties. In this study, we utilize a recently developed technique for independently measuring the capillary pressure and permeability to determine the equivalent minimum capillary radii and contact angle of water within micropillar wick structures. In this method, the experimentally measured dryout threshold of a wick structure at different wicking lengths is fit to Darcy's law to extract the maximum capillary pressure generated by the test liquid. The equivalent minimum capillary radii of different wick geometries are determined by measuring the maximum capillary pressures generated using n-hexane as the working fluid. It is found that the equivalent minimum capillary radius is dependent on the diameter of pillars and the spacing between pillars. The equivalent capillary radii of micropillar wicks determined using the new method are found to be up to 7 times greater than the current geometry-based first-order estimates. The contact angle subtended by water at the walls of the micropillars is determined by measuring the capillary pressure generated by water within the arrays and the measured capillary radii for the different geometries. This mean contact angle of water is determined to be 54.7°.

  16. Design considerations for a backlight with switchable viewing angles

    Science.gov (United States)

    Fujieda, Ichiro; Takagi, Yoshihiko; Rahadian, Fanny

    2006-08-01

    Small-sized liquid crystal displays are widely used for mobile applications such as cell phones. Electronic control of a viewing angle range is desired in order to maintain privacy for viewing in public as well as to provide wide viewing angles for solitary viewing. Conventionally, a polymer-dispersed liquid crystal (PDLC) panel is inserted between a backlight and a liquid crystal panel. The PDLC layer either transmits or scatters the light from the backlight, thus providing an electronic control of viewing angles. However, such a display system is obviously thick and expensive. Here, we propose to place an electronically-controlled, light-deflecting device between an LED and a light-guide of a backlight. For example, a liquid crystal lens is investigated for other applications and its focal length is controlled electronically. A liquid crystal phase grating either transmits or diffracts an incoming light depending on whether or not a periodic phase distribution is formed inside its liquid crystal layer. A bias applied to such a device will control the angular distribution of the light propagating inside a light-guide. Output couplers built in the light-guide extract the propagating light to outside. They can be V-shaped grooves, pyramids, or any other structures that can refract, reflect or diffract light. When any of such interactions occur, the output couplers translate the changes in the propagation angles into the angular distribution of the output light. Hence the viewing-angle characteristic can be switched. The designs of the output couplers and the LC devices are important for such a backlight system.

  17. Universal shift of the Brewster angle and disorder-enhanced delocalization of p waves in stratified random media.

    Science.gov (United States)

    Lee, Kwang Jin; Kim, Kihong

    2011-10-10

    We study theoretically the propagation and the Anderson localization of p-polarized electromagnetic waves incident obliquely on randomly stratified dielectric media with weak uncorrelated Gaussian disorder. Using the invariant imbedding method, we calculate the localization length and the disorder-averaged transmittance in a numerically precise manner. We find that the localization length takes an extremely large maximum value at some critical incident angle, which we call the generalized Brewster angle. The disorder-averaged transmittance also takes a maximum very close to one at the same incident angle. Even in the presence of an arbitrarily weak disorder, the generalized Brewster angle is found to be substantially different from the ordinary Brewster angle in uniform media. It is a rapidly increasing function of the average dielectric permittivity and approaches 90° when the average relative dielectric permittivity is slightly larger than two. We make a remarkable observation that the dependence of the generalized Brewster angle on the average dielectric permittivity is universal in the sense that it is independent of the strength of disorder. We also find, surprisingly, that when the average relative dielectric permittivity is less than one and the incident angle is larger than the generalized Brewster angle, both the localization length and the disorder-averaged transmittance increase substantially as the strength of disorder increases in a wide range of the disorder parameter. In other words, the Anderson localization of incident p waves can be weakened by disorder in a certain parameter regime.

  18. "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.

  19. Effect of injection angle, density ratio, and viscosity on droplet formation in a microfluidic T-junction

    Directory of Open Access Journals (Sweden)

    Mohammad Yaghoub Abdollahzadeh Jamalabadi

    2017-07-01

    Full Text Available The T-junction microchannel device makes available a sharp edge to form micro-droplets from bio-material solutions. This article investigates the effects of injection angle, flow rate ratio, density ratio, viscosity ratio, contact angle, and slip length in the process of formation of uniform droplets in microfluidic T-junctions. The governing equations were solved by the commercial software. The results show that contact angle, slip length, and injection angles near the perpendicular and parallel conditions have an increasing effect on the diameter of generated droplets, while flow rate, density and viscosity ratios, and other injection angles had a decreasing effect on the diameter. Keywords: Microfluidics, Droplet formation, Flow rate ratio, Density ratio

  20. Interaction between benzenedithiolate and gold: Classical force field for chemical bonding

    Science.gov (United States)

    Leng, Yongsheng; Krstić, Predrag S.; Wells, Jack C.; Cummings, Peter T.; Dean, David J.

    2005-06-01

    We have constructed a group of classical potentials based on ab initio density-functional theory (DFT) calculations to describe the chemical bonding between benzenedithiolate (BDT) molecule and gold atoms, including bond stretching, bond angle bending, and dihedral angle torsion involved at the interface between the molecule and gold clusters. Three DFT functionals, local-density approximation (LDA), PBE0, and X3LYP, have been implemented to calculate single point energies (SPE) for a large number of molecular configurations of BDT-1, 2 Au complexes. The three DFT methods yield similar bonding curves. The variations of atomic charges from Mulliken population analysis within the molecule/metal complex versus different molecular configurations have been investigated in detail. We found that, except for bonded atoms in BDT-1, 2 Au complexes, the Mulliken partial charges of other atoms in BDT are quite stable, which significantly reduces the uncertainty in partial charge selections in classical molecular simulations. Molecular-dynamics (MD) simulations are performed to investigate the structure of BDT self-assembled monolayer (SAM) and the adsorption geometry of S adatoms on Au (111) surface. We found that the bond-stretching potential is the most dominant part in chemical bonding. Whereas the local bonding geometry of BDT molecular configuration may depend on the DFT functional used, the global packing structure of BDT SAM is quite independent of DFT functional, even though the uncertainty of some force-field parameters for chemical bonding can be as large as ˜100%. This indicates that the intermolecular interactions play a dominant role in determining the BDT SAMs global packing structure.

  1. 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.

  2. The Effect of Nylon and Polyester Peel Ply Surface Preparation on the Bond Quality of Composite Laminates

    Science.gov (United States)

    Moench, Molly K.

    The preparation of the surfaces to be bonded is critical to the success of composite bonds. Peel ply surface preparation is attractive from a manufacturing and quality assurance standpoint, but is a well known example of the extremely system-specific nature of composite bonds. This study examined the role of the surface energy, morphology, and chemistry left by peel ply removal in resulting bond quality. It also evaluated the use of contact angle surface energy measurement techniques for predicting the resulting bond quality of a prepared surface. The surfaces created by preparing three aerospace fiber-reinforced composite prepregs were compared when prepared with a nylon vs a polyester peel ply. The prepared surfaces were characterized with contact angle measurements with multiple fluids, scanning electron microscopy (SEM), and x-ray electron spectroscopy. The laminates were bonded with aerospace grade film adhesives. Bond quality was assessed via double cantilever beam testing followed by optical and scanning electron microscopy of the fracture surfaces.The division was clear between strong bonds (GIC of 600- 1000J/m2 and failure in cohesion) and weak bonds (GIC of 80-400J/m2 and failure in adhesion). All prepared laminates showed the imprint of the peel ply texture and evidence of peel ply remnants after fabric removal, either through SEM or XPS. Within an adhesive system, large amounts of SEM-visible peel ply material transfer correlated with poor bond quality and cleaner surfaces with higher bond quality. The both sides of failed weak bonds showed evidence of peel ply remnants under XPS, showing that at least some failure is occurring through the remnants. The choice of adhesive was found to be significant. AF 555 adhesive was more tolerant of peel ply contamination than MB 1515-3. Although the bond quality results varied substantially between tested combinations, the total surface energies of all prepared surfaces were very similar. Single fluid contact angle

  3. 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

  4. 7 CFR 1726.27 - Contractor's bonds.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 11 2010-01-01 2010-01-01 false Contractor's bonds. 1726.27 Section 1726.27... AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES General § 1726.27 Contractor's bonds. (a) RUS Form 168b, Contractor's Bond, shall be used when a contractor's bond is required by RUS Forms 200, 257...

  5. Oregon School Bond Manual. Fourth Edition.

    Science.gov (United States)

    Oregon State Dept. of Education, Salem.

    The manual is intended to guide attorneys and officials of school districts in the issuance and sale of school district bonds. Purchasers of school district bonds rely on the recommendations of accredited bond attorneys who render opinions concerning the validity and legality of bond issues offered for sale. This manual is designed to assist in…

  6. Oregon School Bond Manual. Fifth Edition.

    Science.gov (United States)

    Oregon State Dept. of Education, Salem.

    To help school districts comply with Oregon's school bond laws, this manual provides guidelines for school district attorneys and personnel in the issuance and sale of school bonds. The document describes the proper time sequence of the bonding procedure, including elections, school board authorizations, necessary certificates, bond registration…

  7. Relaxation of the chemical bond skin chemisorption size matter ZTP mechanics H2O myths

    CERN Document Server

    Sun, Chang Q

    2014-01-01

    The aim of this book is to explore the detectable properties of a material to the parameters of bond and non-bond involved and to clarify the interdependence of various properties. This book is composed of four parts; Part I deals with the formation and relaxation dynamics of bond and non-bond during chemisorptions with uncovering of the correlation among the chemical bond, energy band, and surface potential barrier (3B) during reactions; Part II is focused on the relaxation of bonds between atoms with fewer neighbors than the ideal in bulk with unraveling of the bond order-length-strength (BOLS) correlation mechanism, which clarifies the nature difference between nanostructures and bulk of the same substance; Part III deals with the relaxation dynamics of bond under heating and compressing with revealing of rules on the temperature-resolved elastic and plastic properties of low-dimensional materials; Part IV is focused on the asymmetric relaxation dynamics of the hydrogen bond (O:H-O) and the anomalous behav...

  8. Shear Bond Strengths and Morphological Evaluation of Filled and Unfilled Adhesive Interfaces to Enamel and Dentine

    Science.gov (United States)

    Mortazavi, Vajihesadat; Fathi, Mohammadhosein; Ataei, Ebrahim; Khodaeian, Niloufar; Askari, Navid

    2012-01-01

    In this laboratory study shear bond strengths of three filled and one unfilled adhesive systems to enamel and dentine were compared. Forty-eight extracted intact noncarious human mandibular molars were randomly assigned to two groups of 24 one for bonding to enamel and the other for bonding to dentine. Buccal and lingual surfaces of each tooth were randomly assigned for application of each one of filled (Prime & Bond NT (PBNT), Optibond Solo Plus (OBSP), and Clearfil SE Bond (CSEB)) and unfilled (Single Bond (SB)) adhesive systems (n = 12). A universal resin composite was placed into the translucent plastic cylinders (3 mm in diameter and 2 mm in length) and seated against the enamel and dentine surfaces and polymerized for 40 seconds. Shear bond strength was determined using a universal testing machine, and the results were statistically analyzed using two-way ANOVA, one-way ANOVA, t-test, and Tukey HSD post hoc test with a 5% level of significance.There were no statistically significant differences in bond strength between the adhesive systems in enamel, but CSEB and SB exhibited significantly higher and lower bond strength to dentine, respectively, than the other tested adhesive systems while there were no statistically significant differences between PBNT and OBSP. PMID:23209471

  9. Shear Bond Strengths and Morphological Evaluation of Filled and Unfilled Adhesive Interfaces to Enamel and Dentine

    Directory of Open Access Journals (Sweden)

    Vajihesadat Mortazavi

    2012-01-01

    Full Text Available In this laboratory study shear bond strengths of three filled and one unfilled adhesive systems to enamel and dentine were compared. Forty-eight extracted intact noncarious human mandibular molars were randomly assigned to two groups of 24 one for bonding to enamel and the other for bonding to dentine. Buccal and lingual surfaces of each tooth were randomly assigned for application of each one of filled (Prime & Bond NT (PBNT, Optibond Solo Plus (OBSP, and Clearfil SE Bond (CSEB and unfilled (Single Bond (SB adhesive systems (n=12. A universal resin composite was placed into the translucent plastic cylinders (3 mm in diameter and 2 mm in length and seated against the enamel and dentine surfaces and polymerized for 40 seconds. Shear bond strength was determined using a universal testing machine, and the results were statistically analyzed using two-way ANOVA, one-way ANOVA, t-test, and Tukey HSD post hoc test with a 5% level of significance.There were no statistically significant differences in bond strength between the adhesive systems in enamel, but CSEB and SB exhibited significantly higher and lower bond strength to dentine, respectively, than the other tested adhesive systems while there were no statistically significant differences between PBNT and OBSP.

  10. Electronic properties of interfaces produced by silicon wafer hydrophilic bonding

    Energy Technology Data Exchange (ETDEWEB)

    Trushin, Maxim

    2011-07-15

    The thesis presents the results of the investigations of electronic properties and defect states of dislocation networks (DNs) in silicon produced by wafers direct bonding technique. A new insight into the understanding of their very attractive properties was succeeded due to the usage of a new, recently developed silicon wafer direct bonding technique, allowing to create regular dislocation networks with predefined dislocation types and densities. Samples for the investigations were prepared by hydrophilic bonding of p-type Si (100) wafers with same small misorientation tilt angle ({proportional_to}0.5 ), but with four different twist misorientation angles Atw (being of < , 3 , 6 and 30 , respectively), thus giving rise to the different DN microstructure on every particular sample. The main experimental approach of this work was the measurements of current and capacitance of Schottky diodes prepared on the samples which contained the dislocation network at a depth that allowed one to realize all capabilities of different methods of space charge region spectroscopy (such as CV/IV, DLTS, ITS, etc.). The key tasks for the investigations were specified as the exploration of the DN-related gap states, their variations with gradually increasing twist angle Atw, investigation of the electrical field impact on the carrier emission from the dislocation-related states, as well as the establishing of the correlation between the electrical (DLTS), optical (photoluminescence PL) and structural (TEM) properties of DNs. The most important conclusions drawn from the experimental investigations and theoretical calculations can be formulated as follows: - DLTS measurements have revealed a great difference in the electronic structure of small-angle (SA) and large-angle (LA) bonded interfaces: dominating shallow level and a set of 6-7 deep levels were found in SA-samples with Atw of 1 and 3 , whereas the prevalent deep levels - in LA-samples with Atw of 6 and 30 . The critical twist

  11. The paediatric Bohler's angle and crucial angle of Gissane: a case series

    Directory of Open Access Journals (Sweden)

    Crawford Haemish A

    2011-01-01

    Full Text Available Abstract Background Bohler's angle and the crucial angle of Gissane can be used to assess calcaneal fractures. While the normal adult values of these angles are widely known, the normal paediatric values have not yet been established. Our aim is to investigate Bohler's angle and the crucial angle of Gissane in a paediatric population and establish normal paediatric reference values. Method We measured Bohler's angle and the crucial angle of Gissane using normal plain ankle radiographs of 763 patients from birth to 14 years of age completed over a five year period from July 2003 to June 2008. Results In our paediatric study group, the mean Bohler's angle was 35.2 degrees and the mean crucial angle of Gissane was 111.3 degrees. In an adult comparison group, the mean Bohler's angle was 39.2 degrees and the mean crucial angle of Gissane was 113.8 degrees. The differences in Bohler's angle and the crucial angle of Gissane between these two groups were statistically significant. Conclusion We have presented the normal values of Bohler's angle and the crucial angle of Gissane in a paediatric population. These values may provide a useful comparison to assist with the management of the paediatric calcaneal fracture.

  12. 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.

  13. Welding, Bonding and Fastening, 1984

    Science.gov (United States)

    Buckley, J. D. (Editor); Stein, B. A. (Editor)

    1985-01-01

    A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Soceity, and Society of Manufacturing Engineers conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

  14. Three methods to measure RH bond energies

    International Nuclear Information System (INIS)

    Berkowitz, J.; Ellison, G.B.; Gutman, D.

    1993-01-01

    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

  15. Knee Moment-Angle Characteristics and Semitendinosus Muscle Morphology in Children with Spastic Paresis Selected for Medial Hamstring Lengthening.

    Science.gov (United States)

    Haberfehlner, Helga; Jaspers, Richard T; Rutz, Erich; Becher, Jules G; Harlaar, Jaap; van der Sluijs, Johannes A; Witbreuk, Melinda M; Romkes, Jacqueline; Freslier, Marie; Brunner, Reinald; Maas, Huub; Buizer, Annemieke I

    2016-01-01

    To increase knee range of motion and improve gait in children with spastic paresis (SP), the semitendinosus muscle (ST) amongst other hamstring muscles is frequently lengthened by surgery, but with variable success. Little is known about how the pre-surgical mechanical and morphological characteristics of ST muscle differ between children with SP and typically developing children (TD). The aims of this study were to assess (1) how knee moment-angle characteristics and ST morphology in children with SP selected for medial hamstring lengthening differ from TD children, as well as (2) how knee moment-angle characteristics and ST morphology are related. In nine SP and nine TD children, passive knee moment-angle characteristics and morphology of ST (i.e. fascicle length, muscle belly length, tendon length, physiological cross-sectional area, and volume) were assessed by hand-held dynamometry and freehand 3D ultrasound, respectively. At net knee flexion moments above 0.5 Nm, more flexed knee angles were found for SP compared to TD children. The measured knee angle range between 0 and 4 Nm was 30% smaller in children with SP. Muscle volume, physiological cross-sectional area, and fascicle length normalized to femur length were smaller in SP compared to TD children (62%, 48%, and 18%, respectively). Sixty percent of the variation in knee angles at 4 Nm net knee moment was explained by ST fascicle length. Altered knee moment-angle characteristics indicate an increased ST stiffness in SP children. Morphological observations indicate that in SP children planned for medial hamstring lengthening, the longitudinal and cross-sectional growth of ST muscle fibers is reduced. The reduced fascicle length can partly explain the increased ST stiffness and, hence, a more flexed knee joint in these SP children.

  16. Diffusionless bonding of aluminum to Zircaloy-2

    International Nuclear Information System (INIS)

    Watson, R.D.

    1965-04-01

    Aluminum can be bonded to zirconium without difficulty even when a thin layer of oxide is present on the surface of the zirconium . No detectable diffusion takes place during the bonding process. The bond layer can be stretched as much. as 8% without affecting the bond. The bond can be heated for 1000 hours at 260 o C (500 o F), and can be water quenched from 260 o C (500 o F) without any noticeable change in the bond strength. An extrusion technique has been devised for making transition sections of aluminum bonded to zirconium which can then be used to join these metals by conventional welding. Welding can be done close to the bond zone without seriously affecting the integrity of the bond. This method of bonding aluminum to Zircaloy-2 is covered by Canadian patent 702,438 January 26, 1965. (author)

  17. Pricing catastrophic bonds for earthquakes in Mexico

    OpenAIRE

    Cabrera, Brenda López

    2006-01-01

    After the occurrence of a natural disaster, the reconstruction can be financed with catastrophic bonds (CAT bonds) or reinsurance. For insurers, reinsurers and other corporations CAT bonds provide multi year protection without the credit risk present in reinsurance. For investors CAT bonds offer attractive returns and reduction of portfolio risk, since CAT bonds defaults are uncorrelated with defaults of other securities. As the study of natural catastrophe models plays an important role in t...

  18. 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.

  19. Medieval orality, mothers, and bonding.

    Science.gov (United States)

    Schwartz, Scott C

    2004-01-01

    The role of women in the Middle Ages was vilification, veneration, and exclusion. Due to the high rates of maternal and infant mortality bonding shifted from the mother-child dyad to one in which the Church, Holy Family, and king acted as pseudo-parents. In art this is suggested by the virtual absence of eye contact between the Virgin and Christ-child. Frustration of early oral needs consequent to lack of adequate mother-child bonding prompted a reactive emphasis on orality in art and legend. A decrease in infant mortality and a reciprocal improvement in mother child bonding contributed to cultural shifts in how self-realization would be accomplished during the Renaissance and in the later emergence of secular humanism.

  20. Atomistic spectrometrics of local bond-electron-energy pertaining to Na and K clusters

    Energy Technology Data Exchange (ETDEWEB)

    Bo, Maolin [Key Laboratory of Low-Dimensional Materials and Application Technologies, Ministry of Education, Xiangtan University, Hunan 411105 (China); Wang, Yan, E-mail: YWang8@hnust.edu.cn [School of Information and Electronic Engineering, Hunan University of Science and Technology, Hunan 411201 (China); Huang, Yongli; Liu, Yonghui [Key Laboratory of Low-Dimensional Materials and Application Technologies, Ministry of Education, Xiangtan University, Hunan 411105 (China); Li, Can [Center for Coordination Bond Engineering, School of Materials Science and Engineering, China Jiliang University, Hangzhou 330018 (China); Sun, Chang Q., E-mail: ecqsun@ntu.edu.sg [NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2015-01-15

    Graphical abstract: - Highlights: • Coordination environment resolves electron binding-energy shift of Na and K clusters. • Cohesive energy of the representative bond determines the core-level shift. • XPS derives the energy level of an isolated atom and its bulk shift. • XPS derives the local bond length, bond energy, binding energy density. - Abstract: Consistency between density functional theory calculations and photoelectron spectroscopy measurements confirmed our predications on the undercoordination-induced local bond relaxation and core level shift of Na and K clusters. It is clarified that the shorter and stronger bonds between under-coordinated atoms cause local densification and local potential well depression and shift the electron binding-energy accordingly. Numerical consistency turns out the energy levels for an isolated Na (E{sub 2p} = 31.167 eV) and K (E{sub 3p} = 18.034 eV) atoms and their respective bulk shifts of 2.401 eV and 2.754 eV, which is beyond the scope of conventional approaches. This strategy has also resulted in quantification of the local bond length, bond energy, binding energy density, and atomic cohesive energy associated with the undercoordinated atoms.

  1. A theoretical perspective of the nature of hydrogen-bond types - the atoms in molecules approach

    Science.gov (United States)

    Vijaya Pandiyan, B.; Kolandaivel, P.; Deepa, P.

    2014-06-01

    Hydrogen bonds and their strength were analysed based on their X-H proton-donor bond properties and the parameters of the H-Y distance (Y proton acceptor). Strong, moderate and weak interactions in hydrogen-bond types were verified through the proton affinities of bases (PA), deprotanation enthalpies of acids (DPE) and the chemical shift (σ). The aromaticity and anti-aromaticity were analysed by means of the NICS (0) (nucleus-independent chemical shift), NICS (1) and ΔNICS (0), ΔNICS (1) of hydrogen-bonded molecules. The strength of a hydrogen bond depends on the capacity of hydrogen atom engrossing into the electronegative acceptor atom. The correlation between the above parameters and their relations were discussed through curve fitting. Bader's theory of atoms in molecules has been applied to estimate the occurrence of hydrogen bonds through eight criteria reported by Popelier et al. The lengths and potential energy shifts have been found to have a strong negative linear correlation, whereas the lengths and Laplacian shifts have a strong positive linear correlation. This study illustrates the common factors responsible for strong, moderate and weak interactions in hydrogen-bond types.

  2. Repeated bonding of fixed retainer increases the risk of enamel fracture.

    Science.gov (United States)

    Chinvipas, Netrporn; Hasegawa, Yuh; Terada, Kazuto

    2014-01-01

    The aim of this study was to investigate the influences of repeated bonding, using 2 different orthodontic adhesive systems, on the shear bond strength (SBS) and the enamel surface morphology. Sixty premolars were divided into 2 groups (n = 30), and either Transbond XT (T group) or Fuji Ortho LC (F group) adhesives were used. SBS was measured 24 h after bonding, using a universal testing machine. Then, the enamel surfaces were investigated and the mode of failure was described using adhesive remnant index (ARI) scores. After each debonding, 10 teeth from each group were examined by scanning electron microscopy to determine the penetration of adhesives, the length of resin tags, and the state of the enamel surface. The other teeth were subjected to two more bonding/debonding procedures. In T group, the second debonding sequences had significantly higher bond strengths than the other sequences. The length of resin tags was greatest in the second debonding sequence, although there was no significant difference. In F group, the SBS increased with further rebonding and the failure mode tended towards cohesive failure. In both groups, the ARI scores increased with rebonding. Enamel loss could have occurred with both adhesives, although the surfaces appeared unchanged to the naked eye. From this study, we suggest that enamel damage caused by repeated bonding is of concern. To prevent bond failure, we should pay attention to the adhesion method used for bondable retainers.

  3. A thermodynamic model of contact angle hysteresis.

    Science.gov (United States)

    Makkonen, Lasse

    2017-08-14

    When a three-phase contact line moves along a solid surface, the contact angle no longer corresponds to the static equilibrium angle but is larger when the liquid is advancing and smaller when the liquid is receding. The difference between the advancing and receding contact angles, i.e., the contact angle hysteresis, is of paramount importance in wetting and capillarity. For example, it determines the magnitude of the external force that is required to make a drop slide on a solid surface. Until now, fundamental origin of the contact angle hysteresis has been controversial. Here, this origin is revealed and a quantitative theory is derived. The theory is corroborated by the available experimental data for a large number of solid-liquid combinations. The theory is applied in modelling the contact angle hysteresis on a textured surface, and these results are also in quantitative agreement with the experimental data.

  4. Self-assembly of alkanethiolates directs sulfur bonding with GaAs(100)

    Energy Technology Data Exchange (ETDEWEB)

    Mancheno-Posso, Pablo; Muscat, Anthony J., E-mail: muscat@email.arizona.edu

    2017-03-01

    Highlights: • Alkanethiolate monolayers were formed on GaAs(100) using a 20 min liquid immersion. • The longest chain containing 20 CH{sub 2} groups protected the surface for 30 min from reoxidation. • A reaction-diffusion model shows that oxygen diffusion through the carbon chains is fast. • Alkanethiolates protect the surface by reducing the reaction rate of oxygen with the surface. • Assembly of the alkane chains directs sulfur atoms to bond to the surface. - Abstract: Molecules that contain linear alkane chains self-assemble on a variety of surfaces changing the degree of wetting, lubricity, and reactivity. We report on the reoxidation of GaAs(100) in air after adsorbing five alkanethiols (C{sub n}H{sub 2n+1}-SH where n = 3, 6, 12, 18, 20) and one alkanedithiol (HS-(CH{sub 2}){sub 8}-SH) deposited from the liquid phase. The alignment of the alkane chains forms a self-assembled layer, however, air diffuses readily through the carbon layer and reaches the surface. The impact of alignment is to improve the bonding of sulfur with the surface atoms which reduces the oxidation rate based on fitting the data to a reaction-diffusion model. The layer thickness and molecular density scale linearly with the number of carbon atoms in the alkane chain. The thickness of the alkanethiolate (RS{sup −}) layer grows by 0.87 ± 0.06 Å for each C atom in the chain and the surface density by 0.13 ± 0.03 molecule per nm{sup 2} per C atom up to a coverage of 5.0 molecules/nm{sup 2} for n = 20 or 0.8 monolayer. The surface coverage increases with length because interactions between methylene (CH{sub 2}) groups in neighboring chains reduce the tilt angle of the molecules with the surface normal. The tight packing yields areas per alkanethiolate as low as 20 Å{sup 2} for n = 20. The amount of C in the layer divided by the chain length is approximately constant up to n = 12 but increases sharply by a factor of 2–4× for n = 18 and 20 based on the C 1s X

  5. Small-angle scattering study of mesoscopic structures in charged gel and their evolution on dehydration

    DEFF Research Database (Denmark)

    Sugiyama, Masaaki; Annaka, Masahiko; Hara, Kazuhiro

    2003-01-01

    Mesoscopic structures, with length scales similar to10(2) Angstrom, were investigated by small-angle X-ray and neutron scattering (SAXS and SANS) in several N-isopropylacrylamide-sodium acrylate (NIPA-SA) copolymeric hydrogels with varying [NIPA]/[SA] ratios and water contents. The SAXS experimen...

  6. The neutron small-angle camera D11 at the high-flux reactor, Grenoble

    International Nuclear Information System (INIS)

    Ibel, K.

    1976-01-01

    The neutron small-angle scattering system at the high-flux reactor in Grenoble consists of three major parts: the supply of cold neutrons via bent neutron guides; the small-angle camera D11; and the data handling facilities. The camera D11 has an overall length of 80 m. The effective length of the camera is variable. The full length of the collimator before the fixed sample position can be reduced by movable neutron guides; the second flight path of 40 m full length contains detector sites in various positions. Thus a large range of momentum transfers can be used with the same relative resolution. Scattering angles between 5 x 10 -4 and 0.5 rad and neutron wavelengths from 0.2 to 2.0 nm are available. A large-area position-sensitive detector is used which allows simultaneous recording of intensities scattered at different angles; it is a multiwire proportional chamber. 3808 elements of 1 cm 2 are arranged in a two-dimensional matrix. (Auth.)

  7. Effects of diameter and helical angle of flute on the flow evenness of ...

    African Journals Online (AJOL)

    Jane

    2011-10-24

    Oct 24, 2011 ... of shaft, flute shape, width of slot and wrapping angle. (Turgut et al., 1995, 1996; ... Figure 1. Technical properties of fluted roller used in this study. average length ... The study was conducted for the ground speed of 1.5 m s-1 ...

  8. Longitudinal changes of angle configuration in primary angle-closure suspects: the Zhongshan Angle-Closure Prevention Trial.

    Science.gov (United States)

    Jiang, Yuzhen; Chang, Dolly S; Zhu, Haogang; Khawaja, Anthony P; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M; He, Mingguang; Friedman, David S; Foster, Paul J

    2014-09-01

    To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Longitudinal cohort study. Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (Pgonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8-1.6) in treated eyes and 1.6°/year (95% CI, 1.3-2.0) in untreated eyes (P<0.001). Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period. Copyright © 2014 American Academy of Ophthalmology. Published by

  9. 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-...

  10. Bond Pricing with Default Risk

    OpenAIRE

    Saa-Requejo, Jesus; Santa-Clara, Pedro

    1997-01-01

    We offer a new model for pricing bonds subject to default risk. The event of default is remodeled as the first time that a state variable that captures the solvency of the issue goes below a certain level. The payoff to the bond in case of default is a constant fraction of the value of a security with the same promised payoffs but without the risk of default. We show that our model is very tractable under different models of interest rate risk and of the interaction between default risk and i...

  11. The qualitative criterion of transient angle stability

    DEFF Research Database (Denmark)

    Lyu, R.; Xue, Y.; Xue, F.

    2015-01-01

    In almost all the literatures, the qualitative assessment of transient angle stability extracts the angle information of generators based on the swing curve. As the angle (or angle difference) of concern and the threshold value rely strongly on the engineering experience, the validity and robust...... of these criterions are weak. Based on the stability mechanism from the extended equal area criterion (EEAC) theory and combining with abundant simulations of real system, this paper analyzes the criterions in most literatures and finds that the results could be too conservative or too optimistic. It is concluded...

  12. On the accuracy of triple phase boundary lengths calculated from tomographic image data

    DEFF Research Database (Denmark)

    Jørgensen, Peter Stanley; Yakal-Kremski, Kyle; Wilson, James

    2014-01-01

    to systematic errors in TPB estimates. Here, two approaches for calculating the TPB density are compared to investigate how different TPB aspects such as curvature, orientation, and phase contact angles affect the results. The first approach applies a correction factor to the TPB length calculated by simply...

  13. Influence of inflow angle on flexible flap aerodynamic performance

    International Nuclear Information System (INIS)

    Zhao, H Y; Ye, Z; Li, Z M; Li, C

    2013-01-01

    Large scale wind turbines have larger blade lengths and weights, which creates new challenges for blade design. This paper selects NREL S809 airfoil, and uses the parameterized technology to realize the flexible trailing edge deformation, researches the dynamic aerodynamic characteristics in the process of continuous flexible deformation, analyses the influence of inflow angle on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With inflow angle increases, dynamic lift-drag coefficient hysteresis loop shape deviation occurs, even turns into different shapes. Appropriate swing angle can improve the flap lift coefficient, but may cause early separation of flow. To improve the overall performance of wind turbine blades, different angular control should be used at different cross sections, in order to achieve the best performance

  14. Anterior segment changes after pharmacologic mydriasis using Pentacam and optical coherence tomography in angle closure suspects

    Directory of Open Access Journals (Sweden)

    Jing-Min Guo

    2015-10-01

    Full Text Available AIM:To compare the dynamic changes of anterior segment parameters especially iris morphology induced by pharmacologic mydriasis between angle closure suspects and normal controls.METHODS:The study group comprised 19 eyes of 19 angle closure suspects and 19 eyes of 19 age- and sex-matched normal open-angle eyes. Pentacam and optical coherence tomography measurements before and 30min after instillation of compound tropicamide eye drop were performed and compared. Biometric evaluations of iris tomography and anterior chamber angle were estimated by a customized image-processing software.RESULTS:Baseline axial length, iris cross sectional area and volume did not differ significantly between angle closure suspects and normal controls. Angle closure suspects had smaller pupil size, narrower anterior segment dimension and axial length, thinner iris with greater curve in comparison with normal controls. Pharmacologic mydriasis led to significant increments in iris thickness at 750 μm, anterior chamber depth and volume, whereas significant decrements in iris curve, cross sectional area and volume in both groups. Angle opening distance at 500 μm was increased significantly in normal controls (from 0.465±0.115 mm to 0.539±0.167 mm, P=0.009, but not in angle closure suspects (from 0.125±0.100 mm to 0.145±0.131 mm, P=0.326. Iris volume change per millimeter of pupil dilation (△IV/△PD decreased significantly less in angle closure suspects than normal controls (-2.47±1.33 mm2 vs -3.63±1.58 mm2, P=0.019. Linear regression analysis showed that the change of angle opening distance at 500 μm was associated most with the change of central anterior chamber depth (β=0.841, P=0.002 and △IV/△PD (β=0.028, P=0.002, followed by gender (β=0.062, P=0.032.CONCLUSION:Smaller iris volume decrement per millimeter of pupil dilation is related significantly with the less anterior angle opening in angle closure suspects after pharmacologic mydriasis. Dynamic

  15. A two-angle model of dynamic wetting in microscale capillaries under low capillary numbers with experiments.

    Science.gov (United States)

    Lei, Da; Lin, Mian; Li, Yun; Jiang, Wenbin

    2018-06-15

    An accurate model of the dynamic contact angle θ d is critical for the calculation of capillary force in applications like enhanced oil recovery, where the capillary number Ca ranges from 10 -10 to 10 -5 and the Bond number Bo is less than 10 -4 . The rate-dependence of the dynamic contact angle under such conditions remains blurred, and is the main target of this study. Featuring with pressure control and interface tracking, the innovative experimental system presented in this work achieves the desired ranges of Ca and Bo, and enables the direct optical measurement of dynamic contact angles in capillaries as tiny as 40 × 20 (width × height) μm and 80 × 20 μm. The advancing and receding processes of wetting and nonwetting liquids were tested. The dynamic contact angle was confirmed velocity-independent with 10 -9  contact line velocity V = 0.135-490 μm/s) and it can be described by a two-angle model with desirable accuracy. A modified two-angle model was developed and an empirical form was obtained from experiments. For different liquids contacting the same surface, the advancing angle θ adv approximately equals the static contact angle θ o . The receding angle θ rec was found to be a linear function of θ adv , in good agreement with our and other experiments from the literature. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Predicting backbone Cα angles and dihedrals from protein sequences by stacked sparse auto-encoder deep neural network.

    Science.gov (United States)

    Lyons, James; Dehzangi, Abdollah; Heffernan, Rhys; Sharma, Alok; Paliwal, Kuldip; Sattar, Abdul; Zhou, Yaoqi; Yang, Yuedong

    2014-10-30

    Because a nearly constant distance between two neighbouring Cα atoms, local backbone structure of proteins can be represented accurately by the angle between C(αi-1)-C(αi)-C(αi+1) (θ) and a dihedral angle rotated about the C(αi)-C(αi+1) bond (τ). θ and τ angles, as the representative of structural properties of three to four amino-acid residues, offer a description of backbone conformations that is complementary to φ and ψ angles (single residue) and secondary structures (>3 residues). Here, we report the first machine-learning technique for sequence-based prediction of θ and τ angles. Predicted angles based on an independent test have a mean absolute error of 9° for θ and 34° for τ with a distribution on the θ-τ plane close to that of native values. The average root-mean-square distance of 10-residue fragment structures constructed from predicted θ and τ angles is only 1.9Å from their corresponding native structures. Predicted θ and τ angles are expected to be complementary to predicted ϕ and ψ angles and secondary structures for using in model validation and template-based as well as template-free structure prediction. The deep neural network learning technique is available as an on-line server called Structural Property prediction with Integrated DEep neuRal network (SPIDER) at http://sparks-lab.org. Copyright © 2014 Wiley Periodicals, Inc.

  17. Optimum Tilt Angle at Tropical Region

    Directory of Open Access Journals (Sweden)

    S Soulayman

    2015-02-01

    Full Text Available : One of the important parameters that affect the performance of a solar collector is its tilt angle with the horizon. This is because of the variation of tilt angle changes the amount of solar radiation reaching the collector surface. Meanwhile, is the rule of thumb, which says that solar collector Equator facing position is the best, is valid for tropical region? Thus, it is required to determine the optimum tilt as for Equator facing and for Pole oriented collectors. In addition, the question that may arise: how many times is reasonable for adjusting collector tilt angle for a definite value of surface azimuth angle? A mathematical model was used for estimating the solar radiation on a tilted surface, and to determine the optimum tilt angle and orientation (surface azimuth angle for the solar collector at any latitude. This model was applied for determining optimum tilt angle and orientation in the tropical zones, on a daily basis, as well as for a specific period. The optimum angle was computed by searching for the values for which the radiation on the collector surface is a maximum for a particular day or a specific period. The results reveal that changing the tilt angle 12 times in a year (i.e. using the monthly optimum tilt angle maintains approximately the total amount of solar radiation near the maximum value that is found by changing the tilt angle daily to its optimum value. This achieves a yearly gain in solar radiation of 11% to 18% more than the case of a solar collector fixed on a horizontal surface.

  18. Reaction-bonded silicon nitride

    International Nuclear Information System (INIS)

    Porz, F.

    1982-10-01

    Reaction-bonded silicon nitride (RBSN) has been characterized. The oxidation behaviour in air up to 1500 0 C and 3000 h and the effects of static and cyclic oxidation on room-temperature strength have been studied. (orig./IHOE) [de

  19. Breaking Rules – Making Bonds

    Indian Academy of Sciences (India)

    IAS Admin

    unusual because it has a pair of non-bonding electrons. So we would classify it ... you would expect the boron to be electron rich with a formal oxidation state of ... Principles of Structure and Reactivity, 4th Edition, Pearson Education, 2008. [3].

  20. 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

  1. Analysis of Disulfide Bond Formation

    NARCIS (Netherlands)

    Braakman, Ineke; Lamriben, Lydia; van Zadelhoff, Guus; Hebert, Daniel N.

    2017-01-01

    In this unit, protocols are provided for detection of disulfide bond formation in cultures of intact cells and in an in vitro translation system containing isolated microsomes or semi-permeabilized cells. First, the newly synthesized protein of interest is biosynthetically labeled with radioactive

  2. [Posterior ceramic bonded partial restorations].

    Science.gov (United States)

    Mainjot, Amélie; Vanheusden, Alain

    2006-01-01

    Posterior ceramic bonded partial restorations are conservative and esthetic approaches for compromised teeth. Overlays constitute a less invasive alternative for tooth tissues than crown preparations. With inlays and onlays they are also indicated in case of full arch or quadrant rehabilitations including several teeth. This article screens indications and realization of this type of restorations.

  3. 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,...

  4. Sharper angle, higher risk? The effect of cutting angle on knee mechanics in invasion sport athletes.

    Science.gov (United States)

    Schreurs, Mervin J; Benjaminse, Anne; Lemmink, Koen A P M

    2017-10-03

    Cutting is an important skill in team-sports, but unfortunately is also related to non-contact ACL injuries. The purpose was to examine knee kinetics and kinematics at different cutting angles. 13 males and 16 females performed cuts at different angles (45°, 90°, 135° and 180°) at maximum speed. 3D kinematics and kinetics were collected. To determine differences across cutting angles (45°, 90°, 135° and 180°) and sex (female, male), a 4×2 repeated measures ANOVA was conducted followed by post hoc comparisons (Bonferroni) with alpha level set at α≤0.05a priori. At all cutting angles, males showed greater knee flexion angles than females (pcutting angles with no differences in the amount of knee flexion -42.53°±8.95°, females decreased their knee flexion angle from -40.6°±7.2° when cutting at 45° to -36.81°±9.10° when cutting at 90°, 135° and 180° (pcutting towards sharper angles (pcutting angles and then stabilized compared to the 45° cutting angle (pcutting to sharper angles (pcutting angles demand different knee kinematics and kinetics. Sharper cutting angles place the knee more at risk. However, females and males handle this differently, which has implications for injury prevention. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Page 1 '---------------------------- Presenting features ofprimary angle ...

    African Journals Online (AJOL)

    coma were assessed. The diagnosis of primary angle-closure glaucoma was made on presentation if the intra-ocular pressure was > 21 mmHg, or if a glaucomatous visual field was found, in the presence of a partially or totally closed angle or peripheral anterior synechiae. Provocation tests were not performed. Patients ...

  6. Gaugings at angles from orientifold reductions

    International Nuclear Information System (INIS)

    Roest, Diederik

    2009-01-01

    We consider orientifold reductions to N= 4 gauged supergravity in four dimensions. A special feature of this theory is that different factors of the gauge group can have relative angles with respect to the electro-magnetic SL(2) symmetry. These are crucial for moduli stabilization and de Sitter vacua. We show how such gaugings at angles generically arise in orientifold reductions.

  7. Automatic Cobb Angle Determination From Radiographic Images

    NARCIS (Netherlands)

    Sardjono, Tri Arief; Wilkinson, Michael H. F.; Veldhuizen, Albert G.; van Ooijen, Peter M. A.; Purnama, Ketut E.; Verkerke, Gijsbertus J.

    2013-01-01

    Study Design. Automatic measurement of Cobb angle in patients with scoliosis. Objective. To test the accuracy of an automatic Cobb angle determination method from frontal radiographical images. Summary of Background Data. Thirty-six frontal radiographical images of patients with scoliosis. Methods.

  8. Practical evaluation of action-angle variables

    International Nuclear Information System (INIS)

    Boozer, A.H.

    1984-02-01

    A practical method is described for establishing action-angle variables for a Hamiltonian system. That is, a given nearly integrable Hamiltonian is divided into an exactly integrable system plus a perturbation in action-angle form. The transformation of variables, which is carried out using a few short trajectory integrations, permits a rapid determination of trajectory properties throughout a phase space volume

  9. Contact angles on a soft solid: from Young's law to Neumann's law.

    Science.gov (United States)

    Marchand, Antonin; Das, Siddhartha; Snoeijer, Jacco H; Andreotti, Bruno

    2012-12-07

    The contact angle that a liquid drop makes on a soft substrate does not obey the classical Young's relation, since the solid is deformed elastically by the action of the capillary forces. The finite elasticity of the solid also renders the contact angles differently from those predicted by Neumann's law, which applies when the drop is floating on another liquid. Here, we derive an elastocapillary model for contact angles on a soft solid by coupling a mean-field model for the molecular interactions to elasticity. We demonstrate that the limit of a vanishing elastic modulus yields Neumann's law or a variation thereof, depending on the force transmission in the solid surface layer. The change in contact angle from the rigid limit to the soft limit appears when the length scale defined by the ratio of surface tension to elastic modulus γ/E reaches the range of molecular interactions.

  10. Apparent contact angle and contact angle hysteresis on liquid infused surfaces.

    Science.gov (United States)

    Semprebon, Ciro; McHale, Glen; Kusumaatmaja, Halim

    2016-12-21

    We theoretically investigate the apparent contact angle and contact angle hysteresis of a droplet placed on a liquid infused surface. We show that the apparent contact angle is not uniquely defined by material parameters, but also has a dependence on the relative size between the droplet and its surrounding wetting ridge formed by the infusing liquid. We derive a closed form expression for the contact angle in the limit of vanishing wetting ridge, and compute the correction for small but finite ridge, which corresponds to an effective line tension term. We also predict contact angle hysteresis on liquid infused surfaces generated by the pinning of the contact lines by the surface corrugations. Our analytical expressions for both the apparent contact angle and contact angle hysteresis can be interpreted as 'weighted sums' between the contact angles of the infusing liquid relative to the droplet and surrounding gas phases, where the weighting coefficients are given by ratios of the fluid surface tensions.

  11. A lattice determination of gA and left angle x right angle from overlap fermions

    International Nuclear Information System (INIS)

    Guertler, M.; Schiller, A.; Streuer, T.; Freie Univ. Berlin

    2004-10-01

    We present results for the nucleon's axial charge g A and the first moment left angle x right angle of the unpolarized parton distribution function from a simulation of quenched overlap fermions. (orig.)

  12. Laser peripheral iridoplasty for angle-closure.

    Science.gov (United States)

    Ng, Wai Siene; Ang, Ghee Soon; Azuara-Blanco, Augusto

    2012-02-15

    Angle-closure glaucoma is a leading cause of irreversible blindness in the world. Treatment is aimed at opening the anterior chamber angle and lowering the IOP with medical and/or surgical treatment (e.g. trabeculectomy, lens extraction). Laser iridotomy works by eliminating pupillary block and widens the anterior chamber angle in the majority of patients. When laser iridotomy fails to open the anterior chamber angle, laser iridoplasty may be recommended as one of the options in current standard treatment for angle-closure. Laser peripheral iridoplasty works by shrinking and pulling the peripheral iris tissue away from the trabecular meshwork. Laser peripheral iridoplasty can be used for crisis of acute angle-closure and also in non-acute situations.   To assess the effectiveness of laser peripheral iridoplasty in the treatment of narrow angles (i.e. primary angle-closure suspect), primary angle-closure (PAC) or primary angle-closure glaucoma (PACG) in non-acute situations when compared with any other intervention. In this review, angle-closure will refer to patients with narrow angles (PACs), PAC and PACG. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 12), MEDLINE (January 1950 to January 2012), EMBASE (January 1980 to January 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 5 January 2012. We included only randomised controlled trials (RCTs) in this review. Patients with narrow angles, PAC or PACG were eligible. We excluded studies that included only patients with acute presentations

  13. Spectroscopic investigation and computational analysis of charge transfer hydrogen bonded reaction between 3-aminoquinoline with chloranilic acid in 1:1 stoichiometric ratio

    Science.gov (United States)

    Al-Ahmary, Khairia M.; Alenezi, Maha S.; Habeeb, Moustafa M.

    2015-10-01

    Charge transfer hydrogen bonded reaction between the electron donor (proton acceptor) 3-aminoquinoline with the electron acceptor (proton donor) chloranilic acid (H2CA) has been investigated experimentally and theoretically. The experimental work included the application of UV-vis spectroscopy to identify the charge transfer band of the formed complex, its molecular composition as well as estimating its formation constants in different solvent included acetonitrile (AN), methanol (MeOH), ethanol (EtOH) and chloroform (CHL). It has been recorded the presence of new absorption bands in the range 500-550 nm attributing to the formed complex. The molecular composition of the HBCT complex was found to be 1:1 (donor:acceptor) in all studied solvents based on continuous variation and photometric titration methods. In addition, the calculated formation constants from Benesi-Hildebrand equation recorded high values, especially in chloroform referring to the formation of stable HBCT complex. Infrared spectroscopy has been applied for the solid complex where formation of charge and proton transfer was proven in it. Moreover, 1H and 13C NMR spectroscopies were used to characterize the formed complex where charge and proton transfers were reconfirmed. Computational analysis included the use of GAMESS computations as a package of ChemBio3D Ultr12 program were applied for energy minimization and estimation of the stabilization energy for the produced complex. Also, geometrical parameters (bond lengths and bond angles) of the formed HBCT complex were computed and analyzed. Furthermore, Mullikan atomic charges, molecular potential energy surface, HOMO and LUMO molecular orbitals as well as assignment of the electronic spectra of the formed complex were presented. A full agreement between experimental and computational analysis has been found especially in the existence of the charge and proton transfers and the assignment of HOMO and LUMO molecular orbitals in the formed complex as

  14. Scoliosis angle. Conceptual basis and proposed definition

    Energy Technology Data Exchange (ETDEWEB)

    Marklund, T [Linkoepings Hoegskola (Sweden)

    1978-01-01

    The most commonly used methods of assessing the scoliotic deviation measure angles that are not clearly defined in relation to the anatomy of the patient. In order to give an anatomic basis for such measurements it is proposed to define the scoliotic deviation as the deviation the vertebral column makes with the sagittal plane. Both the Cobb and the Ferguson angles may be based on this definition. The present methods of measurement are then attempts to measure these angles. If the plane of these angles is parallel to the film, the measurement will be correct. Errors in the measurements may be incurred by the projection. A hypothetical projection, called a 'rectified orthogonal projection', is presented, which correctly represents all scoliotic angles in accordance with these principles. It can be constructed in practice with the aid of a computer and by performing measurements on two projections of the vertebral column; a scoliotic curve can be represented independent of the kyphosis and lordosis.

  15. Experimental study of crossing angle collision

    International Nuclear Information System (INIS)

    Chen, T.; Rice, D.; Rubin, D.; Sagan, D.; Tigner, M.

    1993-01-01

    The non-linear coupling due to the beam-beam interaction with crossing angle has been studied. The major effect of a small (∼12mrad) crossing angle is to excite 5Q x ±Q s =integer coupling resonance family on large amplitude particles, which results in bad lifetime. On the CESR, a small crossing angle (∼2.4mr) was created at the IP and a reasonable beam-beam tune-shift was achieved. The decay rate of the beam is measured as a function of horizontal tune with and without crossing angle. The theoretical analysis, simulation and experimental measurements have a good agreement. The resonance strength as a function of crossing angle is also measured

  16. Hydrogen bonded C-H···Y (Y = O, S, Hal) molecular complexes: A natural bond orbital analysis

    Science.gov (United States)

    Isaev, A. N.

    2016-03-01

    Hydrogen bonded C-H···Y complexes formed by H2O, H2S molecules, hydrogen halides, and halogen-ions with methane, halogen substituted methane as well as with the C2H2 and NCH molecules were studied at the MP2/aug-cc-pVDZ level. The structure of NBOs corresponding to lone pair of acceptor Y, n Y, and vacant anti-σ-bond C-H of proton donor was analyzed and estimates of second order perturbation energy E(2) characterizing donor-acceptor n Y → σ C-H * charge-transfer interaction were obtained. Computational results for complexes of methane and its halogen substituted derivatives show that for each set of analogous structures, the EnY→σ*C-H (2) energy tends to grow with an increase in the s-component percentage in the lone pair NBO of acceptor Y. Calculations for different C···Y distances show that the equilibrium geometries of complexes lie in the region where the E(2) energy is highest and it changes symbatically with the length of the covalent E-H bond when the R(C···Y) distance is varied. The performed analysis allows us to divide the hydrogen bonded complexes into two groups, depending on the pattern of overlapping for NBOs of the hydrogen bridge.

  17. Bi-directional ultrasonic wave coupling to FBGs in continuously bonded optical fiber sensing.

    Science.gov (United States)

    Wee, Junghyun; Hackney, Drew; Bradford, Philip; Peters, Kara

    2017-09-01

    Fiber Bragg grating (FBG) sensors are typically spot-bonded onto the surface of a structure to detect ultrasonic waves in laboratory demonstrations. However, to protect the rest of the optical fiber from any environmental damage during real applications, bonding the entire length of fiber, called continuous bonding, is commonly done. In this paper, we investigate the impact of continuously bonding FBGs on the measured Lamb wave signal. In theory, the ultrasonic wave signal can bi-directionally transfer between the optical fiber and the plate at any adhered location, which could potentially produce output signal distortion for the continuous bonding case. Therefore, an experiment is performed to investigate the plate-to-fiber and fiber-to-plate signal transfer, from which the signal coupling coefficient of each case is theoretically estimated based on the experimental data. We demonstrate that the two coupling coefficients are comparable, with the plate-to-fiber case approximately 19% larger than the fiber-to-plate case. Finally, the signal waveform and arrival time of the output FBG responses are compared between the continuous and spot bonding cases. The results indicate that the resulting Lamb wave signal output is only that directly detected at the FBG location; however, a slight difference in signal waveform is observed between the two bonding configurations. This paper demonstrates the practicality of using continuously bonded FBGs for ultrasonic wave detection in structural health monitoring (SHM) applications.

  18. Effect of Silica fume and superplasticizer on steel-concrete bond

    International Nuclear Information System (INIS)

    Esfahani, M. R.

    2001-01-01

    This paper presents a study on the influence of silica fume and super plasticizer on bond strength. The study included tests of fifty short length pull-out specimens in five series. The effect of silica fume and super plasticizer on bond strength was evaluated separately by tests of specimens made of concretes with similar strengths but different admixtures. Test results showed that the addition of silica fume in the concrete mixture had not a negative effect on bond strength. Also, there was not a considerable decrease in bond strength of specimens made of concrete with super plasticizer. Comparing the measured bond strengths normalized with respect to the square root of the concrete compressive strength, it was seen that the normalized bond strength increased with the concrete strength. this result agrees with the model previously proposed by the author for local bond strength. For the specimens made of high strength concrete including silica fume and super plasticizer, the normalized bond strength did not increase with the concrete strength

  19. Monitoring of desert dune topography by multi angle sensors

    Science.gov (United States)

    Yun, J.; Kim, J.; Choi, Y.; Yun, H.

    2011-12-01

    Nowadays, the sandy desert is rapidly expanding world widely and results in a lot of risks in the socio-econimical aspects as well as the anthropogenic activities. For example, the increasing occurrences of mineral dust storm which presumably originated from the sandy deserts in northwest China become a serious threat in human activities as well as public health over Far East Asian area as the interpretation by the MODIS analysis (Zhang et al., 2007) and the particle trajectory simulation with HYSPLYT (HYbrid Single-Particle Lagrangian Integrated Trajectory) (Kim et al., 2011) identified. Since the sand dune activity has been recognized as an essential indicator of the progressive desertification, it is important to establish the monitoring method for the variations of topographic properties by the dune activities such as local roughness. Thus it will provide the crucial data about the extent and the transition of sandy desert. For example, it is well known the aerodynamic roughness lengths Zo which can be driven from the specialized sensor such as POLDER (POLarization and Directionality of the Earth's Reflectances) is essential to understand desert dune characteristics. However, for the multi temporal observation of dune fields, the availability of data set to extract Zo is limited. Therefore, we employed MISR (Multi angle imaging Spectro Radiometer) image sequence to extract multi angle topographic parameters such as NDAI (Normalized Difference Angular Index) or the variation of radiance with the viewing geometry which are representing the characteristics of target desert topography instead of Zo. In our approach, NDAI were expanded to the all viewing angles and then compared over the target sandy desert and the surrounding land covers. It showed very strong consistencies according to the land cover type and especially over the dynamic dune fields. On the other hands, the variation of NDAIs of sandy desert combining with the metrological observations were

  20. The Bond Fluctuation Model and Other Lattice Models

    Science.gov (United States)

    Müller, Marcus

    Lattice models constitute a class of coarse-grained representations of polymeric materials. They have enjoyed a longstanding tradition for investigating the universal behavior of long chain molecules by computer simulations and enumeration techniques. A coarse-grained representation is often necessary to investigate properties on large time- and length scales. First, some justification for using lattice models will be given and the benefits and limitations will be discussed. Then, the bond fluctuation model by Carmesin and Kremer [1] is placed into the context of other lattice models and compared to continuum models. Some specific techniques for measuring the pressure in lattice models will be described. The bond fluctuation model has been employed in more than 100 simulation studies in the last decade and only few selected applications can be mentioned.

  1. Apparent Contact Angle and Contact Angle Hysteresis on Liquid Infused Surfaces

    OpenAIRE

    Semprebon, Ciro; McHale, Glen; Kusumaatmaja, Halim

    2016-01-01

    We theoretically investigate the apparent contact angle and contact angle hysteresis of a droplet placed on a liquid infused surface. We show that the apparent contact angle is not uniquely defined by material parameters, but also has a strong dependence on the relative size between the droplet and its surrounding wetting ridge formed by the infusing liquid. We derive a closed form expression for the contact angle in the limit of vanishing wetting ridge, and compute the correction for small b...

  2. 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.

  3. Non-silicon substrate bonding mediated by poly(dimethylsiloxane) interfacial coating

    Science.gov (United States)

    Zhang, Hainan; Lee, Nae Yoon

    2015-02-01

    In this paper, we introduce a simple and robust strategy for bonding poly(dimethylsiloxane) (PDMS) with various thermoplastic substrates to fabricate a thermoplastic-based closed microfluidic device and examine the feasibility of using the proposed method for realizing plastic-plastic bonding. The proposed bonding strategy was realized by first coating amine functionality on an oxidized thermoplastic surface. Next, the amine-functionalized surface was reacted with a monolayer of low-molecular-weight PDMS, terminated with epoxy functionality, by forming a robust amine-epoxy bond. Both the PDMS-coated thermoplastic and PDMS were then oxidized and permanently assembled at 25 °C under a pressure of 0.1 MPa for 15 min, resulting in PDMS-like surfaces on all four inner walls of the microchannel. Surface characterizations were conducted, including water contact angle measurement, X-ray photoelectron spectroscopy (XPS), and fluorescence measurement, to confirm the successful coating of the thin PDMS layer on the plastic surface, and the bond strength was analyzed by conducting a peel test, burst test, and leakage test. Using the proposed method, we could successfully bond various thermoplastics such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polystyrene (PS), and poly(ethylene terephthalate) (PET) with PDMS without the collapse or deformation of the microchannel, and the proposed method was successfully extended to the bonding of two thermoplastics, PMMA, and PC.

  4. A novel bonding method for large scale poly(methyl methacrylate) micro- and nanofluidic chip fabrication

    Science.gov (United States)

    Qu, Xingtian; Li, Jinlai; Yin, Zhifu

    2018-04-01

    Micro- and nanofluidic chips are becoming increasing significance for biological and medical applications. Future advances in micro- and nanofluidics and its utilization in commercial applications depend on the development and fabrication of low cost and high fidelity large scale plastic micro- and nanofluidic chips. However, the majority of the present fabrication methods suffer from a low bonding rate of the chip during thermal bonding process due to air trapping between the substrate and the cover plate. In the present work, a novel bonding technique based on Ar plasma and water treatment was proposed to fully bond the large scale micro- and nanofluidic chips. The influence of Ar plasma parameters on the water contact angle and the effect of bonding conditions on the bonding rate and the bonding strength of the chip were studied. The fluorescence tests demonstrate that the 5 × 5 cm2 poly(methyl methacrylate) chip with 180 nm wide and 180 nm deep nanochannels can be fabricated without any block and leakage by our newly developed method.

  5. Tensile Bond Strength of Self Adhesive Resin Cement After Various Surface Treatment of Enamel.

    Science.gov (United States)

    Sekhri, Sahil; Mittal, Sanjeev; Garg, Sandeep

    2016-01-01

    In self adhesive resin cements adhesion is achieved to dental surface without surface pre-treatment, and requires only single step application. This makes the luting procedure less technique-sensitive and decreases postoperative sensitivity. The purpose of this study was to evaluate bond strength of self adhesive resin after surface treatment of enamel for bonding base metal alloy. On the labial surface of 64 central incisor rectangular base metal block of dimension 6 mm length, 5mm width and 1 mm height was cemented with RelyX U200 and Maxcem Elite self adhesive cements with and without surface treatment of enamel. Surface treatment of enamel was application of etchant, one step bonding agent and both. Tensile bond strength of specimen was measured with universal testing machine at a cross head speed of 1mm/min. Least tensile bond strength (MPa) was in control group i.e. 1.33 (0.32) & 1.59 (0.299), Highest bond strength observed when enamel treated with both etchant and bonding agent i.e. 2.72 (0.43) & 2.97 (0.19) for Relyx U200 and Elite cement. When alone etchant and bonding agent were applied alone bond strength is 2.19 (0.18) & 2.24 (0.47) for Relyx U200, and 2.38 (0.27) 2.49 (0.16) for Max-cem elite. Mean bond strength was higher in case of Max-cem Elite as compared to RelyX U200 resin cement, although differences were non-significant (p > 0.05). Surface treatment of enamel increases the bond strength of self adhesive resin cement.

  6. Tensile Bond Strength of Self Adhesive Resin Cement After Various Surface Treatment of Enamel

    Science.gov (United States)

    Sekhri, Sahil; Garg, Sandeep

    2016-01-01

    Introduction In self adhesive resin cements adhesion is achieved to dental surface without surface pre-treatment, and requires only single step application. This makes the luting procedure less technique-sensitive and decreases postoperative sensitivity. Aim The purpose of this study was to evaluate bond strength of self adhesive resin after surface treatment of enamel for bonding base metal alloy. Materials and Methods On the labial surface of 64 central incisor rectangular base metal block of dimension 6 mm length, 5mm width and 1 mm height was cemented with RelyX U200 and Maxcem Elite self adhesive cements with and without surface treatment of enamel. Surface treatment of enamel was application of etchant, one step bonding agent and both. Tensile bond strength of specimen was measured with universal testing machine at a cross head speed of 1mm/min. Results Least tensile bond strength (MPa) was in control group i.e. 1.33 (0.32) & 1.59 (0.299), Highest bond strength observed when enamel treated with both etchant and bonding agent i.e. 2.72 (0.43) & 2.97 (0.19) for Relyx U200 and Elite cement. When alone etchant and bonding agent were applied alone bond strength is 2.19 (0.18) & 2.24 (0.47) for Relyx U200, and 2.38 (0.27) 2.49 (0.16) for Max-cem elite. Mean bond strength was higher in case of Max-cem Elite as compared to RelyX U200 resin cement, although differences were non–significant (p > 0.05). Conclusion Surface treatment of enamel increases the bond strength of self adhesive resin cement. PMID:26894165

  7. Survival and Growth of Cottonwood Clones After Angle Planting and Base Angle Treatments

    Science.gov (United States)

    W.K. Randall; Harvey E. Kennedy

    1976-01-01

    Presently, commercial cottonwood plantations in the lower Mississippi Valley are established using vertically planted, unrooted cuttings with a flat (90°) base. Neither survival nor first-year growth of a group of six Stoneville clones was improved by angle planting or cutting base angles diagonally. For one clone, survival was significantly better when base angle was...

  8. Joint angles of the ankle, knee, and hip and loading conditions during split squats.

    Science.gov (United States)

    Schütz, Pascal; List, Renate; Zemp, Roland; Schellenberg, Florian; Taylor, William R; Lorenzetti, Silvio

    2014-06-01

    The aim of this study was to quantify how step length and the front tibia angle influence joint angles and loading conditions during the split squat exercise. Eleven subjects performed split squats with an additional load of 25% body weight applied using a barbell. Each subject's movements were recorded using a motion capture system, and the ground reaction force was measured under each foot. The joint angles and loading conditions were calculated using a cluster-based kinematic approach and inverse dynamics modeling respectively. Increases in the tibia angle resulted in a smaller range of motion (ROM) of the front knee and a larger ROM of the rear knee and hip. The external flexion moment in the front knee/hip and the external extension moment in the rear hip decreased as the tibia angle increased. The flexion moment in the rear knee increased as the tibia angle increased. The load distribution between the legs changed squat execution was varied. Our results describing the changes in joint angles and the resulting differences in the moments of the knee and hip will allow coaches and therapists to adapt the split squat exercise to the individual motion and load demands of athletes.

  9. Evidence for intermuscle difference in slack angle in human triceps surae.

    Science.gov (United States)

    Hirata, Kosuke; Kanehisa, Hiroaki; Miyamoto-Mikami, Eri; Miyamoto, Naokazu

    2015-04-13

    This study examined whether the slack angle (i.e., the joint angle corresponding to the slack length) varies among the synergists of the human triceps surae in vivo. By using ultrasound shear wave elastography, shear modulus of each muscle of the triceps surae was measured during passive stretching from 50° of plantar flexion in the knee extended position at an angular velocity of 1°/s in 9 healthy adult subjects. The slack angle of each muscle was determined from the ankle joint angle-shear modulus relationship as the first increase in shear modulus. The slack angle was significantly greater in the medial gastrocnemius (20.7±6.7° plantarflexed position) than in the lateral gastrocnemius (14.9±6.7° plantarflexed position) and soleus (2.0±4.8° dorsiflexed position) and greater in the lateral gastrocnemius than in the soleus. This study provided evidence that the slack angle differs among the triceps surae; the medial gastrocnemius produced passive force at the most plantarflexed position while the slack angle of the soleus was the most dorsiflexed position. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Linear-to-λ-Shape P-O-P Bond Transmutation in Polyphosphates with Infinite (PO3)∞ Chain.

    Science.gov (United States)

    Wang, Ying; Li, Lin; Han, Shujuan; Lei, Bing-Hua; Abudoureheman, Maierhaba; Yang, Zhihua; Pan, Shilie

    2017-09-05

    A new metal polyphosphate, α-CsBa 2 (PO 3 ) 5 , exhibiting the first example of a linear P-O-P bond angle in a one-dimensional (PO 3 ) ∞ chain has been reported. Interestingly, α → β phase transition occurs in CsBa 2 (PO 3 ) 5 along with the P-O-P bonds varying from linear to λ-shape, suggesting that α-CsBa 2 (PO 3 ) 5 with unfavorable linear P-O-P bonds is more stable at ambient temperature.

  11. 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...... 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.......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...

  12. Bond strength of cementitious borehole plugs in welded tuff

    International Nuclear Information System (INIS)

    Akgun, H.; Daemen, J.J.K.

    1991-02-01

    Axial loads on plugs or seals in an underground repository due to gas, water pressures and temperature changes induced subsequent to waste and plug emplacement lead to shear stresses at the plug/rock contact. Therefore, the bond between the plug and rock is a critical element for the design and effectiveness of plugs in boreholes, shafts or tunnels. This study includes a systematic investigation of the bond strength of cementitious borehole plugs in welded tuff. Analytical and numerical analysis of borehole plug-rock stress transfer mechanics is performed. The interface strength and deformation are studied as a function of Young's modulus ratio of plug and rock, plug length and rock cylinder outside-to-inside radius ratio. The tensile stresses in and near an axially loaded plug are analyzed. The frictional interface strength of an axially loaded borehole plug, the effect of axial stress and lateral external stress, and thermal effects are also analyzed. Implications for plug design are discussed. The main conclusion is a strong recommendation to design friction plugs in shafts, drifts, tunnels or boreholes with a minimum length to diameter ratio of four. Such a geometrical design will reduce tensile stresses in the plug and in the host rock to a level which should minimize the risk of long-term deterioration caused by excessive tensile stresses. Push-out tests have been used to determine the bond strength by applying an axial load to cement plugs emplaced in boreholes in welded tuff cylinders. A total of 130 push-out tests have been performed as a function of borehole size, plug length, temperature, and degree of saturation of the host tuff. The use of four different borehole radii enables evaluation of size effects. 119 refs., 42 figs., 20 tabs

  13. Creation of the {pi} angle standard for the flat angle measurements

    Energy Technology Data Exchange (ETDEWEB)

    Giniotis, V; Rybokas, M, E-mail: gi@ap.vtu.l, E-mail: MRybokas@gama.l [Department of Information Technologies, Vilnius Gediminas Technical University, Sauletekio al. 11, 10223 Vilnius-40 (Lithuania)

    2010-07-01

    Angle measurements are based mainly on multiangle prisms - polygons with autocollimators, rotary encoders for high accuracy and circular scales as the standards of the flat angle. Traceability of angle measurements is based on the standard of the plane angle - prism (polygon) calibrated at an appropriate accuracy. Some metrological institutions have established their special test benches (comparators) equipped with circular scales or rotary encoders of high accuracy and polygons with autocollimators for angle calibration purposes. Nevertheless, the standard (etalon) of plane angle - polygon has many restrictions for the transfer of angle unit - radian (rad) and other units of angle. It depends on the number of angles formed by the flat sides of the polygon that is restricted by technological and metrological difficulties related to the production and accuracy determination of the polygon. A possibility to create the standard of the angle equal to {pi} rad or half the circle or the full angle is proposed. It can be created by the circular scale with the rotation axis of very high accuracy and two precision reading instruments, usually, photoelectric microscopes (PM), placed on the opposite sides of the circular scale using the special alignment steps. A great variety of angle units and values can be measured and its traceability ensured by applying the third PM on the scale. Calibration of the circular scale itself and other scale or rotary encoder as well is possible using the proposed method with an implementation of {pi} rad as the primary standard angle. The method proposed enables to assure a traceability of angle measurements at every laboratory having appropriate environment and reading instruments of appropriate accuracy together with a rotary table with the rotation axis of high accuracy - rotation trajectory (runout) being in the range of 0.05 {mu}m. Short information about the multipurpose angle measurement test bench developed is presented.

  14. The adhesive bonding of beryllium structural components

    International Nuclear Information System (INIS)

    Fullerton-Batten, R.C.

    1977-01-01

    Where service conditions permit, adhesive bonding is a highly recommendable, reliable means of joining beryllium structural parts. Several important programs have successfully used adhesive bonding for joining structural and non-structural beryllium components. Adhesive bonding minimizes stress concentrations associated with other joining techniques and considerably improves fatigue resistance. In addition, no degradation of base metal properties occur. In many instances, structural joints can be fabricated more cheaply by adhesive bonding or in combination with adhesive bonding than by any other method used alone. An evaluation program on structural adhesive bonding of beryllium sheet components is described. A suitable surface pretreatment for beryllium adherends prior to bonding is given. Tensile shear strength and fatigue properties of FM 1000 and FM 123-5 adhesive bonded joints are reviewed and compared with data obtained from riveted joints of similar geometry. (author)

  15. Manufacturing study of beryllium bonded structures

    International Nuclear Information System (INIS)

    Onozuka, M.; Hirai, S.; Kikuchi, K.; Oda, Y.; Shimizu, K.

    2004-01-01

    Manufacturing study has been conducted on Be-bonded structures employed in the first-wall panel of the blanket system for the ITER. For Be tiles bonded to the Cu-Cr-Zr alloy heat sink with stainless-steel cooling pipes, a one-axis hot press with two heating process has been used to bond the three materials. First, Cu-alloy and SS materials are bonded diffusively. Then, Be tiles are bonded to the pre-bonded structure under 20 MPa and at 560 degree C. An Al-Si base interlayer has been used to bond Be to the Cu-Alloy. Because of the limited heat processes using a conventional hot press, the manufacturing cost can be minimized. Using the above bonding techniques, a partial mockup of a blanket first-wall panel with 16 Be tiles (with 50 mm in size) has been successfully manufactured. (author)

  16. Angle closure glaucoma in congenital ectropion uvea

    Directory of Open Access Journals (Sweden)

    Grace M. Wang

    2018-06-01

    Full Text Available Purpose: Congenital ectropion uvea is a rare anomaly, which is associated with open, but dysplastic iridocorneal angles that cause childhood glaucoma. Herein, we present 3 cases of angle-closure glaucoma in children with congenital ectropion uvea. Observations: Three children were initially diagnosed with unilateral glaucoma secondary to congenital ectropion uvea at 7, 8 and 13 years of age. The three cases showed 360° of ectropion uvea and iris stromal atrophy in the affected eye. In one case, we have photographic documentation of progression to complete angle closure, which necessitated placement of a glaucoma drainage device 3 years after combined trabeculotomy and trabeculectomy. The 2 other cases, which presented as complete angle closure, also underwent glaucoma drainage device implantation. All three cases had early glaucoma drainage device encapsulation (within 4 months and required additional surgery (cycloablation or trabeculectomy. Conclusions and importance: Congenital ectropion uvea can be associated with angle-closure glaucoma, and placement of glaucoma drainage devices in all 3 of our cases showed early failure due to plate encapsulation. Glaucoma in congenital ectropion uvea requires attention to angle configuration and often requires multiple surgeries to obtain intraocular pressure control. Keywords: Congenital ectropion uvea, Juvenile glaucoma, Angle-closure glaucoma, Glaucoma drainage device

  17. Modified Angle's Classification for Primary Dentition.

    Science.gov (United States)

    Chandranee, Kaushik Narendra; Chandranee, Narendra Jayantilal; Nagpal, Devendra; Lamba, Gagandeep; Choudhari, Purva; Hotwani, Kavita

    2017-01-01

    This study aims to propose a modification of Angle's classification for primary dentition and to assess its applicability in children from Central India, Nagpur. Modification in Angle's classification has been proposed for application in primary dentition. Small roman numbers i/ii/iii are used for primary dentition notation to represent Angle's Class I/II/III molar relationships as in permanent dentition, respectively. To assess applicability of modified Angle's classification a cross-sectional preschool 2000 children population from central India; 3-6 years of age residing in Nagpur metropolitan city of Maharashtra state were selected randomly as per the inclusion and exclusion criteria. Majority 93.35% children were found to have bilateral Class i followed by 2.5% bilateral Class ii and 0.2% bilateral half cusp Class iii molar relationships as per the modified Angle's classification for primary dentition. About 3.75% children had various combinations of Class ii relationships and 0.2% children were having Class iii subdivision relationship. Modification of Angle's classification for application in primary dentition has been proposed. A cross-sectional investigation using new classification revealed various 6.25% Class ii and 0.4% Class iii molar relationships cases in preschool children population in a metropolitan city of Nagpur. Application of the modified Angle's classification to other population groups is warranted to validate its routine application in clinical pediatric dentistry.

  18. Modified angle's classification for primary dentition

    Directory of Open Access Journals (Sweden)

    Kaushik Narendra Chandranee

    2017-01-01

    Full Text Available Aim: This study aims to propose a modification of Angle's classification for primary dentition and to assess its applicability in children from Central India, Nagpur. Methods: Modification in Angle's classification has been proposed for application in primary dentition. Small roman numbers i/ii/iii are used for primary dentition notation to represent Angle's Class I/II/III molar relationships as in permanent dentition, respectively. To assess applicability of modified Angle's classification a cross-sectional preschool 2000 children population from central India; 3–6 years of age residing in Nagpur metropolitan city of Maharashtra state were selected randomly as per the inclusion and exclusion criteria. Results: Majority 93.35% children were found to have bilateral Class i followed by 2.5% bilateral Class ii and 0.2% bilateral half cusp Class iii molar relationships as per the modified Angle's classification for primary dentition. About 3.75% children had various combinations of Class ii relationships and 0.2% children were having Class iii subdivision relationship. Conclusions: Modification of Angle's classification for application in primary dentition has been proposed. A cross-sectional investigation using new classification revealed various 6.25% Class ii and 0.4% Class iii molar relationships cases in preschool children population in a metropolitan city of Nagpur. Application of the modified Angle's classification to other population groups is warranted to validate its routine application in clinical pediatric dentistry.

  19. Preferred nasolabial angle in Middle Eastern population.

    Science.gov (United States)

    Alharethy, Sami

    2017-05-01

    To define the preferred nasolabial angle measurement in Middle Eastern population. An observational study was conducted from January 2012 to January 2016 at the Department of Otolaryngology, Head and Neck Surgery, King Abdulaziz University Hospital, King Saud University, Riyadh, Kingdom of Saudi Arabia. A total of 1027 raters, 506 males, and 521 females were asked to choose the most ideal nasolabial angle for 5 males and 5 females lateral photographs whose nasolabial angle were modified with Photoshop into the following angles (85°, 90°, 95°, 100°, 105°, and 110°). Male raters preferred the angle of 89.5° ± 3.5° (mean ± SD) for males and 90.8° ± 5.6° for females. While female raters preferred the angle of 89.3° ± 3.8° for males and 90.5° ± 4.8° for females. ANOVA test compare means among groups: p: 0.342, and there is no statistically significant difference between groups. The results of our study showed an even more acute angles than degrees found in the literature. It shows that what young generation in our region prefers and clearly reflects that what could be explained as under rotation of the nasal tip in other cultures is just the ideal for some Middle Eastern population.

  20. Weld bonding of stainless steel

    DEFF Research Database (Denmark)

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

    2004-01-01

    . The overall assessment of the weld bonding process is made using several commercial adhesives with varying working times under different surface conditions. The quality of the resulting joints is evaluated by means of macroetching observations, tension-shear tests and peel tests. The theoretical investigation......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...... of the process consists of numerical predictions based on the commercial finite element program SORPAS with the purpose of establishing the most favourable parameters that allow spot-welding through the adhesives....

  1. Structure and bonding in clusters

    International Nuclear Information System (INIS)

    Kumar, V.

    1991-10-01

    We review here the recent progress made in the understanding of the electronic and atomic structure of small clusters of s-p bonded materials using the density functional molecular dynamics technique within the local density approximation. Starting with a brief description of the method, results are presented for alkali metal clusters, clusters of divalent metals such as Mg and Be which show a transition from van der Waals or weak chemical bonding to metallic behaviour as the cluster size grows and clusters of Al, Sn and Sb. In the case of semiconductors, we discuss results for Si, Ge and GaAs clusters. Clusters of other materials such as P, C, S, and Se are also briefly discussed. From these and other available results we suggest the possibility of unique structures for the magic clusters. (author). 69 refs, 7 figs, 1 tab

  2. Bond graph modeling of centrifugal compression systems

    OpenAIRE

    Uddin, Nur; Gravdahl, Jan Tommy

    2015-01-01

    A novel approach to model unsteady fluid dynamics in a compressor network by using a bond graph is presented. The model is intended in particular for compressor control system development. First, we develop a bond graph model of a single compression system. Bond graph modeling offers a different perspective to previous work by modeling the compression system based on energy flow instead of fluid dynamics. Analyzing the bond graph model explains the energy flow during compressor surge. Two pri...

  3. About counterintuitive orbital mixing and bond populations

    International Nuclear Information System (INIS)

    Jorge, F.E.; Giambiagi, M.; Giambiagi, M.S. de

    1983-01-01

    It is shown that negative bond and orbital populations may be avoided by the introduction of a weight factor in a bond index definition, together with a suitable parameterization. The negative bond populations found for first-row metal complexes need not be ascribed to counterintuitive orbital mixing but rather, essentially, to the equipartition of the charge distribution. Different definitions of the bond population are compared for ferrocene and the effects of some parameterizations are discussed. (Author) [pt

  4. A Cat Bond Premium Puzzle?

    OpenAIRE

    Vivek J. Bantwal; Howard C. Kunreuther

    1999-01-01

    Catastrophe Bonds whose payoffs are tied to the occurrence of natural disasters offer insurers the ability to hedge event risk through the capital markets that could otherwise leave them insolvent if concentrated solely on their own balance sheets. At the same time, they offer investors a unique opportunity to enhance their portfolios with an asset that provides an attractive return that is uncorrelated with typical financial securities Despite its attractiveness, spreads in this market remai...

  5. Hydrogen Bonding in DNA Base Pairs: Reconciliation of Theory and Experiment

    NARCIS (Netherlands)

    Fonseca Guerra, C.; Bickelhaupt, F.M.; Snijders, J.G.; Baerends, E.J.

    2000-01-01

    Up till now, there has been a significant disagreement between theory and experiment regarding hydrogen bond lengths in Watson - Crick base pairs. To investigate the possible sources of this discrepancy, we have studied numerous model systems for adenine - thymine (AT) and guanine - cytosine (GC)

  6. Computing angle of arrival of radio signals

    Science.gov (United States)

    Borchardt, John J.; Steele, David K.

    2017-11-07

    Various technologies pertaining to computing angle of arrival of radio signals are described. A system that is configured for computing the angle of arrival of a radio signal includes a cylindrical sheath wrapped around a cylindrical object, where the cylindrical sheath acts as a ground plane. The system further includes a plurality of antennas that are positioned about an exterior surface of the cylindrical sheath, and receivers respectively coupled to the antennas. The receivers output measurements pertaining to the radio signal. A processing circuit receives the measurements and computes the angle of arrival of the radio signal based upon the measurements.

  7. Social impact bonds and their application to preventive health.

    Science.gov (United States)

    Fitzgerald, John L

    2013-05-01

    Although preventive health in Australia has been acknowledged as central to national health and wellbeing, efforts to reform the delivery of preventive health have to date produced limited results. The financing of preventive health at a national level is based on outcome- or performance-based funding mechanisms; however, delivery of interventions and activities at a state level have not been subjected to outcome-based funding processes. A new financing tool being applied in the area of social services (social impact bonds) has emerged as a possible model for application in the prevention arena. This paper explores key issues in the consideration of this funding model in the prevention arena. When preventive health is conceptualised as a merit good, the role of government is clarified and outcome measures fully articulated, social impact bonds may be a viable funding option to supplement core public health activities. WHAT IS KNOWN ABOUT THE TOPIC? The complexities of outcome monitoring in preventive health are well understood.Likewise, the problem of linking funding to outcomes from preventive health practice has also been debated at length in health policy. However, not much is known about the application of social impact bonds into the preventive health arena.WHAT DOES THIS PAPER ADD? This paper discusses the limitations and opportunities facing the application of the social impact bond financing model in the preventive health arena. This has not been undertaken previously.WHAT ARE THE IMPLICATIONS FOR PRACTITIONERS? Social impact bonds have received significant recent attention from federal and state government treasury departments as potential financing tools for government. Health policy practitioners are watching this space very closely to see the outcomes of a New South Wales trial. Health promotion practitioners and primary care practitioners who deliver preventive services will need to keep abreast of this issue as it will have significant impact on their

  8. Simple inorganic complexes but intricate hydrogen bonding ...

    Indian Academy of Sciences (India)

    Administrator

    We are interested in obtaining single crystals of metal-opda complexes because their crystal structures would show complex hydrogen bonding network due to the presence of. –NH2 groups in the opda ligand (hydrogen bonding donor sites) and inorganic anions having mostly oxo groups (hydrogen bonding acceptor sites) ...

  9. 75 FR 39730 - Tribal Economic Development Bonds

    Science.gov (United States)

    2010-07-12

    ... DEPARTMENT OF THE TREASURY Tribal Economic Development Bonds AGENCY: Department of the Treasury... (``Treasury'') seeks comments from Indian Tribal Governments regarding the Tribal Economic Development Bond... governments, known as ``Tribal Economic Development Bonds,'' under Section 7871(f) of the Internal Revenue...

  10. 30 CFR 800.21 - Collateral bonds.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Collateral bonds. 800.21 Section 800.21 Mineral... FOR SURFACE COAL MINING AND RECLAMATION OPERATIONS UNDER REGULATORY PROGRAMS § 800.21 Collateral bonds. (a) Collateral bonds, except for letters of credit, cash accounts, and real property, shall be...

  11. Are Stock and Corporate Bond Markets Integrated?

    NARCIS (Netherlands)

    van Zundert, J.; Driessen, Joost

    2017-01-01

    This study explores the cross-sectional integration of stock and corporate bond markets by comparing a firm’s expected stock return, as implied by corporate bond spreads, to its realized stock return. We compute expected corporate bond returns by correcting credit spreads for expected losses due to

  12. 36 CFR 9.48 - Performance bond.

    Science.gov (United States)

    2010-07-01

    ... 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 of operations, the operator shall be required to file a suitable performance bond with satisfactory...

  13. Environmentally dependent bond-order potentials: New ...

    Indian Academy of Sciences (India)

    Environmentally dependent bond-order potentials: New developments and applications ... for modelling amorphous structure we found that the and bond integrals are not only transferable between graphite and diamond structures but they are also strongly anisotropic due to inter-plan bonding between graphite sheets.

  14. 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 bu...

  15. Liquidity risk premia in corporate bond markets

    NARCIS (Netherlands)

    Driessen, J.J.A.G.; de Jong, F.C.J.M.

    2012-01-01

    This paper explores the role of liquidity risk in the pricing of corporate bonds. We show that corporate bond returns have significant exposures to fluctuations in treasury bond liquidity and equity market liquidity. Further, this liquidity risk is a priced factor for the expected returns on

  16. 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...

  17. 43 CFR 23.9 - Performance bond.

    Science.gov (United States)

    2010-10-01

    ... 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 shall be required to file a suitable performance bond of not less than $2,000 with satisfactory surety...

  18. 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...

  19. 36 CFR 9.13 - Performance bond.

    Science.gov (United States)

    2010-07-01

    ... 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 operations the operator shall be required to file a suitable performance bond with satisfactory surety...

  20. 27 CFR 24.146 - Bonds.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bonds. 24.146 Section 24.146 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE.... (c) Wine vinegar plant bond. The proprietor of a wine vinegar plant who withdraws wine from a bonded...

  1. Recent Advances in Adhesive Bonding - The Role of Biomolecules, Nanocompounds, and Bonding Strategies in Enhancing Resin Bonding to Dental Substrates.

    Science.gov (United States)

    Münchow, Eliseu A; Bottino, Marco C

    2017-09-01

    To present an overview on the main agents (i.e., biomolecules and nanocompounds) and/or strategies currently available to amplify or stabilize resin-dentin bonding. According to studies retrieved for full text reading (2014-2017), there are currently six major strategies available to overcome resin-dentin bond degradation: (i) use of collagen crosslinking agents, which may form stable covalent bonds with collagen fibrils, thus strengthening the hybrid layer; (ii) use of antioxidants, which may allow further polymerization reactions over time; (iii) use of protease inhibitors, which may inhibit or inactivate metalloproteinases; (iv) modification of the bonding procedure, which may be performed by using the ethanol wet-bonding technique or by applying an additional adhesive (hydrophobic) coating, thereby strengthening the hybrid layer; (v) laser treatment of the substrate prior to bonding, which may cause specific topographic changes in the surface of dental substrates, increasing bonding efficacy; and (vi) reinforcement of the resin matrix with inorganic fillers and/or remineralizing agents, which may positively enhance physico-mechanical properties of the hybrid layer. With the present review, we contributed to the better understanding of adhesion concepts and mechanisms of resin-dentin bond degradation, showing the current prospects available to solve that problematic. Also, adhesively-bonded restorations may be benefited by the use of some biomolecules, nanocompounds or alternative bonding strategies in order to minimize bond strength degradation.

  2. A novel disulfide bond in the SH2 Domain of the C-terminal Src kinase controls catalytic activity.

    Science.gov (United States)

    Mills, Jamie E; Whitford, Paul C; Shaffer, Jennifer; Onuchic, Jose N; Adams, Joseph A; Jennings, Patricia A

    2007-02-02

    The SH2 domain of the C-terminal Src kinase [Csk] contains a unique disulfide bond that is not present in other known SH2 domains. To investigate whether this unusual disulfide bond serves a novel function, the effects of disulfide bond formation on catalytic activity of the full-length protein and on the structure of the SH2 domain were investigated. The kinase activity of full-length Csk decreases by an order of magnitude upon formation of the disulfide bond in the distal SH2 domain. NMR spectra of the fully oxidized and fully reduced SH2 domains exhibit similar chemical shift patterns and are indicative of similar, well-defined tertiary structures. The solvent-accessible disulfide bond in the isolated SH2 domain is highly stable and far from the small lobe of the kinase domain. However, reduction of this bond results in chemical shift changes of resonances that map to a cluster of residues that extend from the disulfide bond across the molecule to a surface that is in direct contact with the small lobe of the kinase domain in the intact molecule. Normal mode analyses and molecular dynamics calculations suggest that disulfide bond formation has large effects on residues within the kinase domain, most notably within the active-site cleft. Overall, the data indicate that reversible cross-linking of two cysteine residues in the SH2 domain greatly impacts catalytic function and interdomain communication in Csk.

  3. Optical fibre angle sensor used in MEMS

    International Nuclear Information System (INIS)

    Golebiowski, J; Milcarz, Sz; Rybak, M

    2014-01-01

    There is a need for displacement and angle measurements in many movable MEMS structures. The use of fibre optical sensors helps to measure micrometre displacements and small rotation angles. Advantages of this type of transducers are their simple design, high precision of processing, low costs and ability of a non-contact measurement. The study shows an analysis of a fibre-optic intensity sensor used for MEMS movable structure rotation angle measurement. An intensity of the light in the photodetector is basically dependent on a distance between a reflecting surface and a head surface of the fibre transmitting arm, and the deflection angle. Experimental tests were made for PMMA 980/1000 plastic fibres, Θ NA =33°. The study shows both analytical and practical results. It proves that calculated and experimental characteristics for the analysed transducers are similar.

  4. Gonioscopy in primary angle closure glaucoma.

    Science.gov (United States)

    Bruno, Christina A; Alward, Wallace L M

    2002-06-01

    Primary angle closure is a condition characterized by obstruction to aqueous humor outflow by the peripheral iris, and results in changes in the iridocorneal angle that are visible through gonioscopic examination. Gonioscopy in these eyes, however, can be difficult. This chapter discusses techniques that might help in the examination. These include beginning the examination with the inferior angle, methods to help in looking over the iris, cycloplegia, locating the corneal wedge, indentation, van Herick estimation, examining the other eye, and topical glycerin. Finally, there is a discussion about the pathology associated with the closed angle, with emphasis on the appearance of iris bombé, plateau iris, and the distinction between iris processes and peripheral anterior synechiae.

  5. Low angle X-ray scattering

    International Nuclear Information System (INIS)

    Torrianni, I.L.

    1983-01-01

    The theoretical and experimental problems appearing in diffraction experiments at very low angles by several kinds of materials are discussed. The importance of synchrotron radiation in such problems is shown. (L.C.) [pt

  6. Directional Wide-Angle Range Finder (DWARF)

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation, the Directional Wide-Angle Range Finder (DWARF) is the creation of a laser range-finder with a wide field-of-view (FOV) and a directional...

  7. Angle measurement with laser feedback instrument.

    Science.gov (United States)

    Chen, Wenxue; Zhang, Shulian; Long, Xingwu

    2013-04-08

    An instrument for angle measurement based on laser feedback has been designed. The measurement technique is based on the principle that when a wave plate placed into a feedback cavity rotates, its phase retardation varies. Phase retardation is a function of the rotating angle of the wave plate. Hence, the angle can be converted to phase retardation. The phase retardation is measured at certain characteristic points identified in the laser outputting curve that are then modulated by laser feedback. The angle of a rotating object can be measured if it is connected to the wave plate. The main advantages of this instrument are: high resolution, compact, flexible, low cost, effective power, and fast response.

  8. Precision Guidance with Impact Angle Requirements

    National Research Council Canada - National Science Library

    Ford, Jason

    2001-01-01

    This paper examines a weapon system precision guidance problem in which the objective is to guide a weapon onto a non-manoeuvring target so that a particular desired angle of impact is achieved using...

  9. Sensitivity of hydrogen bonds of DNA and RNA to hydration, as gauged by 1JNH measurements in ethanol-water mixtures

    International Nuclear Information System (INIS)

    Manalo, Marlon N.; Kong Xiangming; LiWang, Andy

    2007-01-01

    Hydrogen-bond lengths of nucleic acids are (1) longer in DNA than in RNA, and (2) sequence dependent. The physicochemical basis for these variations in hydrogen-bond lengths is unknown, however. Here, the notion that hydration plays a significant role in nucleic acid hydrogen-bond lengths is tested. Watson-Crick N1...N3 hydrogen-bond lengths of several DNA and RNA duplexes are gauged using imino 1 J NH measurements, and ethanol is used as a cosolvent to lower water activity. We find that 1 J NH values of DNA and RNA become less negative with added ethanol, which suggests that mild dehydration reduces hydrogen-bond lengths even as the overall thermal stabilities of these duplexes decrease. The 1 J NH of DNA are increased in 8 mol% ethanol to those of RNA in water, which suggests that the greater hydration of DNA plays a significant role in its longer hydrogen bonds. The data also suggest that ethanol-induced dehydration is greater for the more hydrated G:C base pairs and thereby results in greater hydrogen-bond shortening than for the less hydrated A:T/U base pairs of DNA and RNA

  10. Axial vector mass spectrum and mixing angles

    International Nuclear Information System (INIS)

    Caffarelli, R.V.; Kang, K.

    1976-01-01

    Spectral sum rules of the axial-vector current and axial-vector current-pseudoscalar field are used to study the axial-vector mass spectrum and mixing angles, as well as the decay constants and mixing angles of the pseudoscalar mesons. In general, the result is quite persuasive for the existence of the Jsup(PC) = 1 ++ multiplet in which one has a canonical D-E mixing. (Auth.)

  11. Contact angle hysteresis on superhydrophobic stripes.

    Science.gov (United States)

    Dubov, Alexander L; Mourran, Ahmed; Möller, Martin; Vinogradova, Olga I

    2014-08-21

    We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, ϕS. It is shown that the receding regime is determined by a longitudinal sliding motion of the deformed contact line. Despite an anisotropy of the texture the receding contact angle remains isotropic, i.e., is practically the same in the longitudinal and transverse directions. The cosine of the receding angle grows nonlinearly with ϕS. To interpret this we develop a theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the strong defects due to the elastic energy of the deformed contact line, which scales as ϕS(2)lnϕS. The advancing contact angle was found to be anisotropic, except in a dilute regime, and its value is shown to be determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on ϕS, but a satisfactory fit to the data can only be provided if we generalize the Cassie equation to account for weak defects. The cosine of the transverse advancing angle is much smaller and is maximized at ϕS ≃ 0.5. An explanation of its value can be obtained if we invoke an additional energy due to strong defects in this direction, which is shown to be caused by the adhesion of the drop on solid sectors and is proportional to ϕS(2). Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when ϕS ≤ 0.2.

  12. Small-angle neutron-scattering experiments

    International Nuclear Information System (INIS)

    Hardy, A.D.; Thomas, M.W.; Rouse, K.D.

    1981-04-01

    A brief introduction to the technique of small-angle neutron scattering is given. The layout and operation of the small-angle scattering spectrometer, mounted on the AERE PLUTO reactor, is also described. Results obtained using the spectrometer are presented for three materials (doped uranium dioxide, Magnox cladding and nitrided steel) of interest to Springfields Nuclear Power Development Laboratories. The results obtained are discussed in relation to other known data for these materials. (author)

  13. Radiodiagnosis of Cerebellopontine-angle tumors

    International Nuclear Information System (INIS)

    Weyer, K.H. van de

    1979-01-01

    The most important radiodiagnostic signs of cerebellopontine-angle tumors are demonstrated. The value of plain films and special projections is discussed. The use of recent diagnostic procedures like scintography, CT and cisternography with oily contrast medium is critically analyzed. The advantage and disadvantages of these procedures are discussed according to their usefullness in evaluating size, route of spread and localisation of cerebellopontine-angle tumors. (orig.) [de

  14. Estimating Elevation Angles From SAR Crosstalk

    Science.gov (United States)

    Freeman, Anthony

    1994-01-01

    Scheme for processing polarimetric synthetic-aperture-radar (SAR) image data yields estimates of elevation angles along radar beam to target resolution cells. By use of estimated elevation angles, measured distances along radar beam to targets (slant ranges), and measured altitude of aircraft carrying SAR equipment, one can estimate height of target terrain in each resolution cell. Monopulselike scheme yields low-resolution topographical data.

  15. Expressions for the Total Yaw Angle

    Science.gov (United States)

    2016-09-01

    1. Introduction 1 2. Mathematical Notation 1 3. Total Yaw Expression Derivations 2 3.1 First Derivation 2 3.2 Second Derivation 4 3.3 Other...4 iv Approved for public release; distribution is unlimited. 1. Introduction The total yaw angle, γt , of a ballistic projectile is... elevation angles from spherical coordinates.∗ We again place point A at the end point of V. Now imagine a plane parallel to the y-z plane that includes

  16. Lateral displacement in small angle multiple scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bichsel, H.; Hanson, K.M.; Schillaci, K.M. (Los Alamos National Lab., NM (USA))

    1982-07-01

    Values have been calculated for the average lateral displacement in small angle multiple scattering of protons with energies of several hundred MeV. The calculations incorporate the Moliere distribution which does not make the gaussian approximations of the distribution in projected angle and lateral deflections. Compared to other published data, such approximations can lead to errors in the lateral displacement of up to 10% in water.

  17. Strength of Al and Al-Mg/alumina bonds prepared using ultrahigh vacuum diffusion bonding

    International Nuclear Information System (INIS)

    King, W.E.; Campbell, G.H.; Wien, W.L.; Stoner, S.L.

    1994-01-01

    The authors have measured the cross-breaking strength of Al and Al-Mg alloys bonded with alumina. Diffusion bonding of Al and Al-Mg alloys requires significantly more bonding time than previously thought to obtain complete bonding. In contrast to previous diffusion bonding studies, fracture morphologies are similar to those obtained in bonds formed by liquid phase reaction; i.e., bonds are as strong or stronger than the ceramic; and fracture tends to propagate in the metal for pure Al and near the interface in the ceramic for the alloys. There are indications that the fracture morphology depends on Mg content and therefore on plasticity in the metal

  18. 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.

  19. Angle transducer based on fiber Bragg gratings able for tunnel auscultation

    Science.gov (United States)

    Quintela, A.; Lázaro, J. M.; Quintela, M. A.; Mirapeix, J.; Muñoz-Berti, V.; López-Higuera, J. M.

    2010-09-01

    In this paper an angle transducer based on Fiber Bragg Grating (FBG) is presented. Two gratings are glued to a metallic platen, one in each side. It is insensitive to temperature changes, given that the temperature shifts affect equally to both FBG. When the platen is uniformly bent an uniform strain appears in both sides of the platen. It depends on the bend angle and the platen length and thickness. The transducer has been designed to be used in the auscultation of tunnels during their construction process and during their live time. The transducer design and its characterization are presented.

  20. Small angle scattering of X radiation and slow neutrons in structural analyses of amorphous solids

    International Nuclear Information System (INIS)

    Kostorz, G.

    1980-01-01

    Small angle scattering of x radiation and slow neutrons allows to detect inhomogeneities of the dimension of ten to some thousands of Angstroem by the difference in the scattering length density. The progress made during recent years in the development of apparatusses has created the possibility of solving very complicated problems. A first outline shows that in separation processes as well as in investigating extended defects the method of small angle scattering may provide valuable contributions to the analysis of the non-crystalline state