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Sample records for bond lengths based

  1. 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

  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. 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

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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, ...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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...

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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...

  10. ESTIMATION OF STATURE BASED ON FOOT LENGTH

    Directory of Open Access Journals (Sweden)

    Vidyullatha Shetty

    2015-01-01

    Full Text Available BACKGROUND : Stature is the height of the person in the upright posture. It is an important measure of physical identity. Estimation of body height from its segments or dismember parts has important considerations for identifications of living or dead human body or remains recovered from disasters or other similar conditions. OBJECTIVE : Stature is an important indicator for identification. There are numerous means to establish stature and their significance lies in the simplicity of measurement, applicability and accuracy in prediction. Our aim of the study was to review the relationship between foot length and body height. METHODS : The present study reviews various prospective studies which were done to estimate the stature. All the measurements were taken by using standard measuring devices and standard anthropometric techniques. RESULTS : This review shows there is a correlation between stature and foot dimensions it is found to be positive and statistically highly significant. Prediction of stature was found to be most accurate by multiple regression analysis. CONCLUSIONS : Stature and gender estimation can be done by using foot measurements and stud y will help in medico - legal cases in establishing identity of an individual and this would be useful for Anatomists and Anthropologists to calculate stature based on foot length

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

    Directory of Open Access Journals (Sweden)

    Jlali H

    1999-12-01

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

  12. 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.

  13. 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

  14. 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).

  15. 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)

  16. 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.

  17. 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.

  18. Valuing Convertible Bonds Based on LSRQM Method

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2014-01-01

    Full Text Available Convertible bonds are one of the essential financial products for corporate finance, while the pricing theory is the key problem to the theoretical research of convertible bonds. This paper demonstrates how to price convertible bonds with call and put provisions using Least-Squares Randomized Quasi-Monte Carlo (LSRQM method. We consider the financial market with stochastic interest rates and credit risk and present a detailed description on calculating steps of convertible bonds value. The empirical results show that the model fits well the market prices of convertible bonds in China’s market and the LSRQM method is effective.

  19. 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.

  20. 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

  1. 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)

  2. 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

  3. Competition of hydrogen bonds and halogen bonds in complexes of hypohalous acids with nitrogenated bases.

    Science.gov (United States)

    Alkorta, Ibon; Blanco, Fernando; Solimannejad, Mohammad; Elguero, Jose

    2008-10-30

    A theoretical study of the complexes formed by hypohalous acids (HOX, X = F, Cl, Br, I, and At) with three nitrogenated bases (NH 3, N 2, and NCH) has been carried out by means of ab initio methods, up to MP2/aug-cc-pVTZ computational method. In general, two minima complexes are found, one with an OH...N hydrogen bond and the other one with a X...N halogen bond. While the first one is more stable for the smallest halogen derivatives, the two complexes present similar stabilities for the iodine case and the halogen-bonded structure is the most stable one for the hypoastatous acid complexes.

  4. 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

  5. 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

  6. Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies

    Directory of Open Access Journals (Sweden)

    Laura AlveBastos

    2015-02-01

    Full Text Available Objectives The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Materials and Methods Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE, the specific self-etching adhesive system (Adhesive System P90, 3M ESPE was used with and without pre-etching (Pre-etching/Silorane and Silorane groups. Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray, with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups, or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE (Three-step/Methacrylate group (n = 6. The restored teeth were sectioned into stick-shaped test specimens (1.0 × 1.0 mm, and coupled to a universal test machine (0.5 mm/min to perform microtensile testing. Results Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p < 0.05. However, it was not significantly different from Preetching/Silorane and Methacrylate groups. Conclusions Pre-etching increased bond strength of silorane-based composite specific adhesive system to dentin.

  7. Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies

    OpenAIRE

    Bastos, Laura Alves; Sousa, Ana Beatriz Silva; Drubi-Filho, Brahim; Panzeri Pires-de-Souza, Fernanda de Carvalho; Garcia, Lucas da Fonseca Roberti

    2014-01-01

    Objectives The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Materials and Methods Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/S...

  8. 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.

  9. 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.

  10. Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies.

    Science.gov (United States)

    Bastos, Laura Alves; Sousa, Ana Beatriz Silva; Drubi-Filho, Brahim; Panzeri Pires-de-Souza, Fernanda de Carvalho; Garcia, Lucas da Fonseca Roberti

    2015-02-01

    The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/Silorane and Silorane groups). Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE) were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray), with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups), or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE) (Three-step/Methacrylate group) (n = 6). The restored teeth were sectioned into stick-shaped test specimens (1.0 × 1.0 mm), and coupled to a universal test machine (0.5 mm/min) to perform microtensile testing. Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p adhesive system to dentin.

  11. Bond graph model-based fault diagnosis of hybrid systems

    CERN Document Server

    Borutzky, Wolfgang

    2015-01-01

    This book presents a bond graph model-based approach to fault diagnosis in mechatronic systems appropriately represented by a hybrid model. The book begins by giving a survey of the fundamentals of fault diagnosis and failure prognosis, then recalls state-of-art developments referring to latest publications, and goes on to discuss various bond graph representations of hybrid system models, equations formulation for switched systems, and simulation of their dynamic behavior. The structured text: • focuses on bond graph model-based fault detection and isolation in hybrid systems; • addresses isolation of multiple parametric faults in hybrid systems; • considers system mode identification; • provides a number of elaborated case studies that consider fault scenarios for switched power electronic systems commonly used in a variety of applications; and • indicates that bond graph modelling can also be used for failure prognosis. In order to facilitate the understanding of fault diagnosis and the presented...

  12. 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. :...

  13. 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°.

  14. Speciation of Bactrocera dorsalis complex based on aedeagus length

    International Nuclear Information System (INIS)

    Osamu Iwahashi

    2000-01-01

    A species complex of Bactrocera dorsalis (Hendel) in Southeast Asia is composed of 52 species (Drew and Hancock, 1994) and while some of these species are economically very important, distinguishing them based on morphological characters has been difficult (White and Elson-Harris 1992). Specifically, there is considerable difficulty in differentiating between males of two pairs of sympatric species, B. philippinensis Drew and Hancock/B. occipitalis (Bezzi) in the Philippines and B. carambolae Drew and Hancock/B. papayae Drew and Hancock in Indonesia. This may be, in part, because the evolutionary processes within this species complex are still very dynamic, and that natural hybridisation between sympatric species pairs might be occurring on a regular basis (He and Haymer 1997). Iwaizumi et al. (1997) developed a simple method to differentiate the two sets of sympatric species based on aedeagus lengths. However, these flies had been reared artificially under laboratory conditions and only a small number of specimens (n=5) was used. Consequently, they were not able to obtain a frequency distribution of the aedeagus length for each species. Iwahashi (1998) measured a larger number of wild flies collected on Guimaras Is, Philippines, and found that flies with the aedeagus length of 2.89 mm are B. philippinensis. Iwahashi (1999) also showed that the measurement of the aedeagal length of fruit flies is a reliable characteristic for distinguishing between the 2 sympatric species pairs in the B. dorsalis complex. This being so, it may also be interesting to interpret phylogenetic relationships among B. dorsalis complex species based on the aedeagus length. Thus, aedeagus lengths of different populations of five B. dorsalis complex species are measured and their relationships discussed

  15. Maximum length scale in density based topology optimization

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Wang, Fengwen

    2017-01-01

    The focus of this work is on two new techniques for imposing maximum length scale in topology optimization. Restrictions on the maximum length scale provide designers with full control over the optimized structure and open possibilities to tailor the optimized design for broader range...... of manufacturing processes by fulfilling the associated technological constraints. One of the proposed methods is based on combination of several filters and builds on top of the classical density filtering which can be viewed as a low pass filter applied to the design parametrization. The main idea...

  16. 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

  17. Microshear bond strength of preheated silorane- and methacrylate-based composite resins to dentin.

    Science.gov (United States)

    Demirbuga, Sezer; Ucar, Faruk Izzet; Cayabatmaz, Muhammed; Zorba, Yahya Orcun; Cantekin, Kenan; Topçuoğlu, Hüseyin Sinan; Kilinc, Halil Ibrahim

    2016-01-01

    The aim of this study was to investigate the effect of preheating on microshear bond strength (MSBS) of silorane and methacrylate-based composite resins to human dentin. The teeth were randomly divided into three main groups: (1) composite resins were heated upto 68 °C; (2) cooled to 4 °C; and (3) control [room temperature (RT)]. Each group was then randomly subdivided into four subgroups according to adhesive system used [Solobond M (Voco), All Bond SE (Bisco), Clearfil SE Bond (CSE) (Kuraray), Silorane adhesive system (SAS) (3M ESPE)]. Resin composite cylinders were formed (0.9 mm diameter × 0.7 mm length) and MSBS of each specimen was tested. The preheated groups exhibited the highest MSBS (p composite resins may be an alternative way to increase the MSBS of composites on dentin. © Wiley Periodicals, Inc.

  18. Comparison of the tensile bond strength of high-noble, noble, and base metal alloys bonded to enamel.

    Science.gov (United States)

    Sen, D; Nayir, E; Pamuk, S

    2000-11-01

    Although the bond strengths of various resin composite luting materials have been reported in the literature, the evaluation of these systems with various cast alloys of different compositions has not been completely clarified. To evaluate the tensile bond strength of sandblasted high-noble, noble, and base metal alloys bonded to etched enamel by 2 different bonding agents of different chemical composition: Panavia-Ex (BIS-GMA) and Super-Bond (4-META acrylic). Flat enamel surfaces were prepared on buccal surfaces of 60 extracted noncarious human incisors. Teeth were divided into 3 groups of 20 each. Twenty circular disks of 5 mm diameter were prepared for casting for each group. Group I was cast with a high-noble, group II with a noble, and group III with a base metal alloy. The surfaces of the disks were sandblasted with 250 microm Al(2)O(3). Ten disks of each group were bonded to exposed enamel surfaces with Super-Bond and 10 disks with Panavia-Ex as recommended by the manufacturer. The tensile bond strength was measured with an Instron universal testing machine with a crosshead speed of 0.5 mm/min until failure occurred. Two-way ANOVA was used to evaluate the results. The differences in bond strengths of Super-Bond and Panavia-Ex with different alloys were not significant. The highest bond strengths were obtained in base metal alloys, followed by noble and high-noble alloys. These results were significant. Panavia-Ex and Super-Bond exhibited comparable tensile bond strengths. For both luting agents, the highest bond strengths were achieved with base metal alloys and the lowest with high-noble alloys.

  19. 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

  20. Continuing Bonds in Bereavement: An Attachment Theory Based Perspective

    Science.gov (United States)

    Field, Nigel P.; Gao, Beryl; Paderna, Lisa

    2005-01-01

    An attachment theory based perspective on the continuing bond to the deceased (CB) is proposed. The value of attachment theory in specifying the normative course of CB expression and in identifying adaptive versus maladaptive variants of CB expression based on their deviation from this normative course is outlined. The role of individual…

  1. Supramolecular materials based on hydrogen-bonded polymers

    NARCIS (Netherlands)

    ten Brinke, Gerrit; Ruokolainen, Janne; Ikkala, Olli; Binder, W

    2007-01-01

    Combining supramolecular principles with block copolymer self-assembly offers unique possibilities to create materials with responsive and/or tunable properties. The present chapter focuses on supramolecular materials based on hydrogen bonding and (block co-) polymers. Several cases will be

  2. PMMA to Polystyrene bonding for polymer based microfluidic systems

    KAUST Repository

    Fan, Yiqiang

    2013-03-29

    A thermal bonding technique for Poly (methylmethacrylate) (PMMA) to Polystyrene (PS) is presented in this paper. The PMMA to PS bonding was achieved using a thermocompression method, and the bonding strength was carefully characterized. The bonding temperature ranged from 110 to 125 C with a varying compression force, from 700 to 1,000 N (0.36-0.51 MPa). After the bonding process, two kinds of adhesion quantification methods were used to measure the bonding strength: the double cantilever beam method and the tensile stress method. The results show that the bonding strength increases with a rising bonding temperature and bonding force. The results also indicate that the bonding strength is independent of bonding time. A deep-UV surface treatment method was also provided in this paper to lower the bonding temperature and compression force. Finally, a PMMA to PS bonded microfluidic device was fabricated successfully. © 2013 Springer-Verlag Berlin Heidelberg.

  3. Bond strength test of acrylic artificial teeth with prosthetic base

    Directory of Open Access Journals (Sweden)

    Erna Kurnikasari

    2008-07-01

    Full Text Available Denture consists of acrylic artificial teeth and acrylic prothesis base bond chemically with a bond strength of 315 kgF/cm2. Most of the commercial acrylic artificial teeth do not specify their specifications and all of those acrylic artificial teeth do not include mechanical data (bond strength. The aim of this study is to discover which acrylic artificial teeth meet ADA specification no. 15. This study is a descriptive analytic study performed to 5 acrylic artificial teeth posterior brands commonly used by dentists and technicians. From each brand, 3 sample teeth were taken. The acrylic artificial teeth were prepared into a rectangular shape and were attached between acrylic prothesis base simulation and jigs. The sample was given tensile load using a Universal Testing Machine. The amount of force that causes the teeth to be fractured was recorded and the bond strength was calculated. The results of the study show that the average value for the five acrylic artificial teeth for the five brands were as followed: Brand A, 125.993 kgF/cm2; B, 188.457 kgF/cm2; C, 175.880 kgF/cm2; D, 153.373 kgF/cm2; E, 82.839 kgF/cm2. The data can be tested statistically by using One Way ANOVA test and Dunnett test (alpha = 0.05. From the study, it is concluded that the five acrylic artificial teeth have a bond strength below the ADA specification no. 15.

  4. [The bonding mechanisms of base metals for metal-ceramic crown microstructure analysis of bonding agent and gold bond between porcelain and base metals].

    Science.gov (United States)

    Wang, C C; Hsu, C S

    1996-06-01

    The use of base metal alloys for porcelain fused to a metal crown and bridges has increased recently because of lower price, high hardness, high tensile strength and high elastic modulus. The addition of beryllium to base metal alloys increased fluidity and improved casting fitness. Beryllium also controlled surface oxidation and bonding strength. The bonding agent and gold bonding agent also affected the bonding strength between porcelain and metal alloys. Four commercially available ceramic base alloys were studied (two alloys contained beryllium element, another two did not). The purpose of this investigation was to study the microstructure between porcelain matrix, bonding agent and alloy matrix interfaces. A scanning electron micro-probe analyzer and energy dispersive X-ray spectroscopy (EDXS) were used to study the distribution of elements (Ni, Cr, Mo, Cu, O, Si, Sn, Al) in four base alloys. The following results were obtained: 1. The thickness of the oxidized layer of Rexillium III alloy and Unitbond alloy (contained beryllium) was thinner than Unibond alloy and Wiron 88 alloy (no beryllium). 2. The thickness of the oxidized layer of alloys in air (10 minutes and 30 minutes) was thinner in Unitbond (2.45 microns and 3.80 microns) and thicker in Wiron 88 (4.39 microns and 5.96 microns). 3. The thickness of the oxidized layer occurring for a duration of ten minutes (in vaccum) showed that the Rexillium III alloy was the thinnest (1.93 microns), and Wiron 88 alloy was the thickest (2.30 microns). But in thirty minutes (vacuum), Unitbond alloy was the thinnest (3.37 microns), and Wiron 88 alloy was the thickest (5.51 microns). 4. The intensity of Cr elements was increased obviously near the interface between Unitbond alloy, Wiron 88 alloy (no beryllium) and oxidized layer, but the intensity of Ni and Mo elements was slightly increased. The intensity of Cr element was not increased markedly between Rexillium III alloy, Unitbond alloy (beryllium) and oxidized

  5. 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.

  6. Strengthening of Concrete Structures with cement based bonded composites

    DEFF Research Database (Denmark)

    Täljsten, Björn; Blanksvärd, Thomas

    2008-01-01

    Polymers). The method is very efficient and has achieved world wide attention. However, there are some drawbacks with the use of epoxy, e.g. working environment, compatibility and permeability. Substituting the epoxy adherent with a cement based bonding agent will render a strengthening system...... with improved working environment and better compatibility to the base concrete structure. This study gives an overview of different cement based systems, all with very promising results for structural upgrading. Studied parameters are structural retrofit for bending, shear and confinement. It is concluded...

  7. Continuing bonds in bereavement: an attachment theory based perspective.

    Science.gov (United States)

    Field, Nigel P; Gao, Beryl; Paderna, Lisa

    2005-05-01

    An attachment theory based perspective on the continuing bond to the deceased (CB) is proposed. The value of attachment theory in specifying the normative course of CB expression and in identifying adaptive versus maladaptive variants of CB expression based on their deviation from this normative course is outlined. The role of individual differences in attachment security on effective versus ineffective use of CB in coping with bereavement also is addressed. Finally, the moderating influence of type of loss (e.g., death of a spouse vs. child), culture, and religion on type of CB expression within an overarching attachment framework is discussed.

  8. 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).

  9. 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.

  10. Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds

    Directory of Open Access Journals (Sweden)

    Ibon Alkorta

    2017-10-01

    Full Text Available It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N2, CO, HC≡CH, CH2=CH2, C3H6, PH3, H2S, HCN, H2O, H2CO and NH3 and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H2O, F2, Cl2, Br2, ClF, BrCl, H3SiF, H3GeF, F2CO, CO2, N2O, NO2F, PH2F, AsH2F, SO2, SeO2, SF2, and SeF2 can be represented to good approximation by means of the equation D e = c ′ N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ′ is a constant, conveniently chosen to have the value 1.00 kJ mol−1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1 the hydrogen bond; (2 the halogen bond; (3 the tetrel bond; (4 the pnictogen bond; and (5 the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

  11. Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds.

    Science.gov (United States)

    Alkorta, Ibon; Legon, Anthony C

    2017-10-23

    It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N₂, CO, HC≡CH, CH₂=CH₂, C₃H₆, PH₃, H₂S, HCN, H₂O, H₂CO and NH₃) and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H₂O, F₂, Cl₂, Br₂, ClF, BrCl, H₃SiF, H₃GeF, F₂CO, CO₂, N₂O, NO₂F, PH₂F, AsH₂F, SO₂, SeO₂, SF₂, and SeF₂) can be represented to good approximation by means of the equation D e = c ' N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ' is a constant, conveniently chosen to have the value 1.00 kJ mol -1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1) the hydrogen bond; (2) the halogen bond; (3) the tetrel bond; (4) the pnictogen bond; and (5) the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

  12. Comparison of fish-community size spectra based on length ...

    African Journals Online (AJOL)

    Estimates of fish-community size spectra are promising indicators of the impact of fishing on fish assemblages. Size spectra consist of logarithmic graphs of abundance plotted against fish body size. Size spectra may either be constructed from length frequency data or estimated from the mean sizes and abundances of the ...

  13. Measuring Clearance Mechanics Based on Dynamic Leg Length

    Science.gov (United States)

    Khamis, Sam; Danino, Barry; Hayek, Shlomo; Carmeli, Eli

    2018-01-01

    The aim of this study was to quantify clearance mechanics during gait. Seventeen children diagnosed with hemiplegic cerebral palsy underwent a three-dimensional gait analysis evaluation. Dynamic leg lengths were measured from the hip joint center to the heel, to the ankle joint center and to the forefoot throughout the gait cycle. Significant…

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  15. DNA origami-based nanoribbons: assembly, length distribution, and twist

    Energy Technology Data Exchange (ETDEWEB)

    Jungmann, Ralf; Scheible, Max; Kuzyk, Anton; Pardatscher, Guenther; Simmel, Friedrich C [Lehrstuhl fuer Bioelektronik, Physik-Department and ZNN/WSI, Technische Universitaet Muenchen, Am Coulombwall 4a, 85748 Garching (Germany); Castro, Carlos E, E-mail: simmel@ph.tum.de [Labor fuer Biomolekulare Nanotechnologie, Physik-Department and ZNN/WSI, Technische Universitaet Muenchen, Am Coulombwall 4a, 85748 Garching (Germany)

    2011-07-08

    A variety of polymerization methods for the assembly of elongated nanoribbons from rectangular DNA origami structures are investigated. The most efficient method utilizes single-stranded DNA oligonucleotides to bridge an intermolecular scaffold seam between origami monomers. This approach allows the fabrication of origami ribbons with lengths of several micrometers, which can be used for long-range ordered arrangement of proteins. It is quantitatively shown that the length distribution of origami ribbons obtained with this technique follows the theoretical prediction for a simple linear polymerization reaction. The design of flat single layer origami structures with constant crossover spacing inevitably results in local underwinding of the DNA helix, which leads to a global twist of the origami structures that also translates to the nanoribbons.

  16. DNA origami-based nanoribbons: assembly, length distribution, and twist

    International Nuclear Information System (INIS)

    Jungmann, Ralf; Scheible, Max; Kuzyk, Anton; Pardatscher, Guenther; Simmel, Friedrich C; Castro, Carlos E

    2011-01-01

    A variety of polymerization methods for the assembly of elongated nanoribbons from rectangular DNA origami structures are investigated. The most efficient method utilizes single-stranded DNA oligonucleotides to bridge an intermolecular scaffold seam between origami monomers. This approach allows the fabrication of origami ribbons with lengths of several micrometers, which can be used for long-range ordered arrangement of proteins. It is quantitatively shown that the length distribution of origami ribbons obtained with this technique follows the theoretical prediction for a simple linear polymerization reaction. The design of flat single layer origami structures with constant crossover spacing inevitably results in local underwinding of the DNA helix, which leads to a global twist of the origami structures that also translates to the nanoribbons.

  17. An in vitro study to evaluate the effect of two ethanol-based and two acetone-based dental bonding agents on the bond strength of composite to enamel treated with 10% carbamide peroxide

    Directory of Open Access Journals (Sweden)

    Deepa Basavaraj Benni

    2014-01-01

    Full Text Available Background and Objective: Carbamide peroxide bleaching has been implicated in adversely affecting the bond strength of composite to enamel. The objective of this in vitro study was to evaluate the effect of ethanol-based (Clearfil S 3 bond, Kuraray, Adper Single bond 2, 3M ESPE dental products and acetone-based (Prime and Bond NT, Dentsply, One Step, Bisco bonding agents on the shear bond strength of composite to enamel treated with 10% carbamide peroxide bleaching agent. Materials and Methods: A total of 120 extracted human noncarious permanent incisors were randomly divided into two groups (control and experimental. Experimental group specimens were subjected to a bleaching regimen with a 10% carbamide peroxide bleaching system (Opalescence; Ultradent Products Inc, South Jordan, USA. Composite resin cylinders were bonded to the specimens using four bonding agents and shear bond strength was determined with universal testing machine. Results: There was no statistically significant difference in the shear bond strength between control and experimental groups with both ethanol-based (Clearfil S 3 Bond and Adper Single Bond 2 and acetone-based bonding agent (Prime and Bond NT and One Step. Interpretation and Conclusion: The adverse effect of bleaching on bonding composite to enamel can be reduced or eliminated by using either ethanol- or acetone-based bonding agent. Clinical Significances: Immediate bonding following bleaching procedure can be done using ethanol- or acetone-based bonding agent without compromising bond strength.

  18. PMMA to Polystyrene bonding for polymer based microfluidic systems

    KAUST Repository

    Fan, Yiqiang; Li, Huawei; Yi, Ying; Foulds, Ian G.

    2013-01-01

    temperature ranged from 110 to 125 C with a varying compression force, from 700 to 1,000 N (0.36-0.51 MPa). After the bonding process, two kinds of adhesion quantification methods were used to measure the bonding strength: the double cantilever beam method

  19. Semiempirical search for oxide superconductors based on bond valence sums

    International Nuclear Information System (INIS)

    Tanaka, S.; Fukushima, N.; Niu, H.; Ando, K.

    1992-01-01

    Relationships between crystal structures and electronic states of layered transition-metal oxides are analyzed in the light of bond valence sums. Correlations between the superconducting transition temperature T c and the bond-valence-sum parameters are investigated for the high-T c cuprate compounds. Possibility of making nonsuperconducting oxides superconducting is discussed. (orig.)

  20. Recent mass spectrometry-based techniques and considerations for disulfide bond characterization in proteins.

    Science.gov (United States)

    Lakbub, Jude C; Shipman, Joshua T; Desaire, Heather

    2018-04-01

    Disulfide bonds are important structural moieties of proteins: they ensure proper folding, provide stability, and ensure proper function. With the increasing use of proteins for biotherapeutics, particularly monoclonal antibodies, which are highly disulfide bonded, it is now important to confirm the correct disulfide bond connectivity and to verify the presence, or absence, of disulfide bond variants in the protein therapeutics. These studies help to ensure safety and efficacy. Hence, disulfide bonds are among the critical quality attributes of proteins that have to be monitored closely during the development of biotherapeutics. However, disulfide bond analysis is challenging because of the complexity of the biomolecules. Mass spectrometry (MS) has been the go-to analytical tool for the characterization of such complex biomolecules, and several methods have been reported to meet the challenging task of mapping disulfide bonds in proteins. In this review, we describe the relevant, recent MS-based techniques and provide important considerations needed for efficient disulfide bond analysis in proteins. The review focuses on methods for proper sample preparation, fragmentation techniques for disulfide bond analysis, recent disulfide bond mapping methods based on the fragmentation techniques, and automated algorithms designed for rapid analysis of disulfide bonds from liquid chromatography-MS/MS data. Researchers involved in method development for protein characterization can use the information herein to facilitate development of new MS-based methods for protein disulfide bond analysis. In addition, individuals characterizing biotherapeutics, especially by disulfide bond mapping in antibodies, can use this review to choose the best strategies for disulfide bond assignment of their biologic products. Graphical Abstract This review, describing characterization methods for disulfide bonds in proteins, focuses on three critical components: sample preparation, mass

  1. Ratio-based lengths of intervals to improve fuzzy time series forecasting.

    Science.gov (United States)

    Huarng, Kunhuang; Yu, Tiffany Hui-Kuang

    2006-04-01

    The objective of this study is to explore ways of determining the useful lengths of intervals in fuzzy time series. It is suggested that ratios, instead of equal lengths of intervals, can more properly represent the intervals among observations. Ratio-based lengths of intervals are, therefore, proposed to improve fuzzy time series forecasting. Algebraic growth data, such as enrollments and the stock index, and exponential growth data, such as inventory demand, are chosen as the forecasting targets, before forecasting based on the various lengths of intervals is performed. Furthermore, sensitivity analyses are also carried out for various percentiles. The ratio-based lengths of intervals are found to outperform the effective lengths of intervals, as well as the arbitrary ones in regard to the different statistical measures. The empirical analysis suggests that the ratio-based lengths of intervals can also be used to improve fuzzy time series forecasting.

  2. 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.

  3. Branch length similarity entropy-based descriptors for shape representation

    Science.gov (United States)

    Kwon, Ohsung; Lee, Sang-Hee

    2017-11-01

    In previous studies, we showed that the branch length similarity (BLS) entropy profile could be successfully used for the shape recognition such as battle tanks, facial expressions, and butterflies. In the present study, we proposed new descriptors, roundness, symmetry, and surface roughness, for the recognition, which are more accurate and fast in the computation than the previous descriptors. The roundness represents how closely a shape resembles to a circle, the symmetry characterizes how much one shape is similar with another when the shape is moved in flip, and the surface roughness quantifies the degree of vertical deviations of a shape boundary. To evaluate the performance of the descriptors, we used the database of leaf images with 12 species. Each species consisted of 10 - 20 leaf images and the total number of images were 160. The evaluation showed that the new descriptors successfully discriminated the leaf species. We believe that the descriptors can be a useful tool in the field of pattern recognition.

  4. Metal-mediated DNA base pairing: alternatives to hydrogen-bonded Watson-Crick base pairs.

    Science.gov (United States)

    Takezawa, Yusuke; Shionoya, Mitsuhiko

    2012-12-18

    With its capacity to store and transfer the genetic information within a sequence of monomers, DNA forms its central role in chemical evolution through replication and amplification. This elegant behavior is largely based on highly specific molecular recognition between nucleobases through the specific hydrogen bonds in the Watson-Crick base pairing system. While the native base pairs have been amazingly sophisticated through the long history of evolution, synthetic chemists have devoted considerable efforts to create alternative base pairing systems in recent decades. Most of these new systems were designed based on the shape complementarity of the pairs or the rearrangement of hydrogen-bonding patterns. We wondered whether metal coordination could serve as an alternative driving force for DNA base pairing and why hydrogen bonding was selected on Earth in the course of molecular evolution. Therefore, we envisioned an alternative design strategy: we replaced hydrogen bonding with another important scheme in biological systems, metal-coordination bonding. In this Account, we provide an overview of the chemistry of metal-mediated base pairing including basic concepts, molecular design, characteristic structures and properties, and possible applications of DNA-based molecular systems. We describe several examples of artificial metal-mediated base pairs, such as Cu(2+)-mediated hydroxypyridone base pair, H-Cu(2+)-H (where H denotes a hydroxypyridone-bearing nucleoside), developed by us and other researchers. To design the metallo-base pairs we carefully chose appropriate combinations of ligand-bearing nucleosides and metal ions. As expected from their stronger bonding through metal coordination, DNA duplexes possessing metallo-base pairs exhibited higher thermal stability than natural hydrogen-bonded DNAs. Furthermore, we could also use metal-mediated base pairs to construct or induce other high-order structures. These features could lead to metal-responsive functional

  5. 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.

  6. Fabrication and bonding of thiol-ene-based microfluidic devices

    International Nuclear Information System (INIS)

    Sikanen, Tiina M; Moilanen, Maria-Elisa; Lafleur, Josiane P; Zhuang, Guisheng; Jensen, Thomas G; Kutter, Jörg P

    2013-01-01

    In this work, the bonding strength of microchips fabricated by thiol-ene free-radical polymerization was characterized in detail by varying the monomeric thiol/allyl composition from the stoichiometric ratio (1:1) up to 100% excess of thiol (2:1) or allyl (1:2) functional groups. Four different thiol-ene to thiol-ene bonding combinations were tested by bonding: (i) two stoichiometric layers, (ii) two layers bearing complementary excess of thiols and allyls, (iii) two layers both bearing excess of thiols, or (iv) two layers both bearing excess of allyls. The results showed that the stiffness of the cross-linked polymer plays the most crucial role regarding the bonding strength. The most rigid polymer layers were obtained by using the stoichiometric composition or an excess of allyls, and thus, the bonding combinations (i) and (iv) withstood the highest pressures (up to the cut-off value of 6 bar). On the other hand, excess of thiol monomers yielded more elastic polymer layers and thus decreased the pressure tolerance for bonding combinations (ii) and (iii). By using monomers with more thiol groups (e.g. tetrathiol versus trithiol), a higher cross-linking ratio, and thus, greater stiffness was obtained. Surface characterization by infrared spectroscopy confirmed that the changes in the monomeric thiol/allyl composition were also reflected in the surface chemistry. The flexibility of being able to bond different types of thiol-enes together allows for tuning of the surface chemistry to yield the desired properties for each application. Here, a capillary electrophoresis separation is performed to demonstrate the attractive properties of stoichiometric thiol-ene microchips. (technical note)

  7. Kekulé-based Valence Bond Model.I. The Ground-state Properties of Conjugated π-Systems

    Institute of Scientific and Technical Information of China (English)

    LI,Shu-Hua(黎书华); MA,Jing(马晶); JIANG,Yuan-Sheng(江元生)

    2002-01-01

    The Kekulé-based valence bond ( VB ) method, in which the VB model is solved using covalent Kekulé structures as basis functions, is justified in the present work. This method is dimonstrated to provide satisfactory descriptions for resoance energies and bond ang lengths of benzenoid hydrocarbons, being in good agreement with SCF-MO and experimental results. In additicn, an alternative way of discyssing characters of localizedsubstructures within a polyclic benzenoid system is suggested based upon such sunokufied VB calculations. Finally,the symmetries of VB ground states for nonalternant conjugated systems are also illustrated to be obtainable through these calculations, presenting very useful information for understanding the chemical behaviors of some nonalternant conjugated molecules.

  8. Solvent effects on hydrogen bonds in Watson-Crick, mismatched, and modified DNA base pairs

    NARCIS (Netherlands)

    Poater, Jordi; Swart, Marcel; Guerra, Celia Fonseca; Bickelhaupt, F. Matthias

    2012-01-01

    We have theoretically analyzed a complete series of Watson–Crick and mismatched DNA base pairs, both in gas phase and in solution. Solvation causes a weakening and lengthening of the hydrogen bonds between the DNA bases because of the stabilization of the lone pairs involved in these bonds. We have

  9. Composite adhesive bonds reinforced with microparticle filler based on egg shell waste

    Science.gov (United States)

    Müller, Miroslav; Valášek, Petr

    2018-05-01

    A research on composite adhesive bonds reinforced with waste from hen eggs processing, i.e. egg shell waste (ESW) is based on an assumption of the utilization of agricultural/food production waste. The aim of the research is to gain new pieces of knowledge about the material utilization of ESW, i.e. to evaluate possibilities of the use of various concentrations of ESW microparticles smaller than 100 µm based on hen egg shells as the filler in a structural resin used for a creation of adhesive bonds from bearing metal elements. An adhesive bond strength, an elongation at break and a fracture surface were evaluated within the research on adhesive bonds. The experiment results proved the efficiency of ESW filler in the area of composite adhesive bonds. The adhesive bond strength was increased up of more than 17 % by adding 40 wt.% of ESW microparticles.

  10. Papain-based gel for biochemical caries removal: influence on microtensile bond strength to dentin

    Directory of Open Access Journals (Sweden)

    Evandro Piva

    2008-12-01

    Full Text Available This study investigated the influence of a papain-based gel (Papacárie for chemo-mechanical caries removal on bond strength to dentin. Human molars were assigned to the following groups: Group 1: sound teeth were flattened to expose dentin; Group 2: after flattening of surfaces, the papain-based gel was applied on the sound dentin; Group 3: overlying enamel from carious teeth was removed and mechanical excavation of dentin was conducted; Group 4: chemo-mechanical excavation of carious dentin was conducted using the papain-based gel. The Prime&Bond NT or Clearfil SE Bond adhesive systems were used for restorative procedures. A microtensile bond strength test was performed, and the modes of failure were determined under SEM. The data were submitted to two-way ANOVA and Tukey's test (p < 0.05. No significant differences were observed between the sound dentin groups. For both excavation methods, Clearfil presented a significantly higher bond strength than Prime&Bond NT. Also, for Clearfil, the mechanically excavated samples disclosed a significantly higher bond strength than the chemo-mechanically ones. For Prime&Bond NT, no significant differences were detected between the excavation methods. Predominance of mixed failures for the sound substrate and of adhesive failures for the carious dentin one was detected. The bond strength to carious dentin of the self-etching system was negatively affected by chemo-mechanical excavation using the papain-based gel.

  11. Statistical length of DNA based on AFM image measured by a computer

    International Nuclear Information System (INIS)

    Chen Xinqing; Qiu Xijun; Zhang Yi; Hu Jun; Wu Shiying; Huang Yibo; Ai Xiaobai; Li Minqian

    2001-01-01

    Taking advantage of image processing technology, the contour length of DNA molecule was measured automatically by a computer. Based on the AFM image of DNA, the topography of DNA was simulated into a curve. Then the DNA length was measured automatically by inserting mode. It was shown that the experimental length of a naturally deposited DNA (180.4 +- 16.4 nm) was well consistent with the theoretical length (185.0 nm). Comparing to other methods, the present approach had advantages of precision and automatism. The stretched DNA was also measured. It present approach had advantages of precision and automatism. The stretched DNA was also measured. It was shown that the experimental length (343.6 +- 20.7 nm) was much longer than the theoretical length (307.0 nm). This result indicated that the stretching process had a distinct effect on the DNA length. However, the method provided here avoided the DNA-stretching effect

  12. Measurement and Theory of Hydrogen Bonding Contribution to Isosteric DNA Base Pairs

    OpenAIRE

    Khakshoor, Omid; Wheeler, Steven E.; Houk, K. N.; Kool, Eric T.

    2012-01-01

    We address the recent debate surrounding the ability of 2,4-difluorotoluene (F), a low-polarity mimic of thymine (T), to form a hydrogen-bonded complex with adenine in DNA. The hydrogen bonding ability of F has been characterized as small to zero in various experimental studies, and moderate to small in computational studies. However, recent X-ray crystallographic studies of difluorotoluene in DNA/RNA have indicated, based on interatomic distances, possible hydrogen bonding interactions betwe...

  13. Microstructure and bonding strength of Ni-based alloy coating

    Directory of Open Access Journals (Sweden)

    LIU Qing

    2006-05-01

    Full Text Available A Ni-Cr-B-Si coating technique was developed and successfully applied on austenite grey iron substrate in a conventional resistance furnace under graphite powder protection. The microstructure, phase distribution, chemical composition profile and microhardness along the coating layer depth were investigated. Shear strength of the coating was also tested. Microanalysis shows that the coating is consist of γ-Ni solution and γ-Ni+Ni3B lamellar eutectic, as well as small amount of Cr5B3 particles. Diffusion induced metallurgical bonding occurs at the coating/substrate interfaces, and the higher the temperature, the more sufficient elements diffused, the broader interfusion region and the larger bonding strength, but it has an optimum value. And the bonding strength at the interface can be enable to reach 250-270 MPa, which is nearly the same as that of processed by flame spray. The microhardness along the coating layer depth shows a gradient distribution manner.

  14. Length scale and manufacturability in density-based topology optimization

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Wang, Fengwen; Sigmund, Ole

    2016-01-01

    Since its original introduction in structural design, density-based topology optimization has been applied to a number of other fields such as microelectromechanical systems, photonics, acoustics and fluid mechanics. The methodology has been well accepted in industrial design processes where it can...... provide competitive designs in terms of cost, materials and functionality under a wide set of constraints. However, the optimized topologies are often considered as conceptual due to loosely defined topologies and the need of postprocessing. Subsequent amendments can affect the optimized design...

  15. Analysis of an atom laser based on the spatial control of the scattering length

    International Nuclear Information System (INIS)

    Carpentier, Alicia V.; Michinel, Humberto; Rodas-Verde, Maria I.; Perez-Garcia, Victor M.

    2006-01-01

    In this paper we analyze atom lasers based on the spatial modulation of the scattering length of a Bose-Einstein condensate. We demonstrate, through numerical simulations and approximate analytical methods, the controllable emission of matter-wave bursts and study the dependence of the process on the spatial shape of the scattering length along the axis of emission. We also study the role of an additional modulation of the scattering length in time

  16. Shear Bond Strength of Bracket Bases to Adhesives Based on Bracket Base Design

    Science.gov (United States)

    2016-04-13

    shear bond value when compared to the traditional mesh based orthodontic bracket. Methods: The experimental design included 4 test groups, each... Experimental Design……………………………………………………..…………8 B. Statistical Management of Data………………………………………………….26 IV. RESULTS………………………………………………………………………………28...tooth through which forces may be applied. Through diligent research efforts, clinical experience, and trial and error, this attachment apparatus to

  17. Validity of plant fiber length measurement : a review of fiber length measurement based on kenaf as a model

    Science.gov (United States)

    James S. Han; Theodore. Mianowski; Yi-yu. Lin

    1999-01-01

    The efficacy of fiber length measurement techniques such as digitizing, the Kajaani procedure, and NIH Image are compared in order to determine the optimal tool. Kenaf bast fibers, aspen, and red pine fibers were collected from different anatomical parts, and the fiber lengths were compared using various analytical tools. A statistical analysis on the validity of the...

  18. Errors in Length-weight Parameters at FishBase.org

    OpenAIRE

    Michael Courtney; Simeon Cole-Fletcher; Lucas Marin-Salcedo; Ajaya Rana

    2011-01-01

    Background: FishBase.org is an on-line database of fish related data that has been cited over 1500 times in the fisheries literature. Length-weight relationships in fish traditionally employ the model, W(L) = aL^b^, where L is length and W is weight. Parameters a and b are catalogued by FishBase for a large number of sources and species. FishBase.org detects outliers in a plot of log(a) vs. b to identify dubious length-weight parameters.

  19. Fabrication and bonding of thiol-ene-based microfluidic devices

    DEFF Research Database (Denmark)

    Sikanen, Tiina M; Lafleur, Josiane P.; Moilanen, Maria-Elisa

    2013-01-01

    In this work, the bonding strength of microchips fabricated by thiol-ene free-radical polymerization was characterized in detail by varying the monomeric thiol/allyl composition from the stoichiometric ratio (1:1) up to 100% excess of thiol (2:1) or allyl (1:2) functional groups. Four different...... properties for each application. Here, a capillary electrophoresis separation is performed to demonstrate the attractive properties of stoichiometric thiol-ene microchips....

  20. Hydrogen bond disruption in DNA base pairs from (14)C transmutation.

    Science.gov (United States)

    Sassi, Michel; Carter, Damien J; Uberuaga, Blas P; Stanek, Christopher R; Mancera, Ricardo L; Marks, Nigel A

    2014-09-04

    Recent ab initio molecular dynamics simulations have shown that radioactive carbon does not normally fragment DNA bases when it decays. Motivated by this finding, density functional theory and Bader analysis have been used to quantify the effect of C → N transmutation on hydrogen bonding in DNA base pairs. We find that (14)C decay has the potential to significantly alter hydrogen bonds in a variety of ways including direct proton shuttling (thymine and cytosine), thermally activated proton shuttling (guanine), and hydrogen bond breaking (cytosine). Transmutation substantially modifies both the absolute and relative strengths of the hydrogen bonding pattern, and in two instances (adenine and cytosine), the density at the critical point indicates development of mild covalent character. Since hydrogen bonding is an important component of Watson-Crick pairing, these (14)C-induced modifications, while infrequent, may trigger errors in DNA transcription and replication.

  1. 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

  2. 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.

  3. Microfluidic magnetic switching valves based on aggregates of magnetic nanoparticles: Effects of aggregate length and nanoparticle sizes

    Energy Technology Data Exchange (ETDEWEB)

    Jiemsakul, Thanakorn [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Thanon Phahonyothin, Tambon Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120 (Thailand); Manakasettharn, Supone, E-mail: supone@nanotec.or.th [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Thanon Phahonyothin, Tambon Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120 (Thailand); Kanharattanachai, Sivakorn; Wanna, Yongyuth [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Chalongkrung Road, Bangkok 10520 (Thailand); Wangsuya, Sujint [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Chalongkrung Road, Bangkok 10520 (Thailand); Faculty of Science, Mahidol University, 272 Rama VI Road, Ratchathewi District, Bangkok 10400 (Thailand); Pratontep, Sirapat [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Chalongkrung Road, Bangkok 10520 (Thailand)

    2017-01-15

    We demonstrate microfluidic switching valves using magnetic nanoparticles blended within the working fluid as an alternative microfluidic flow control in microchannels. Y-shaped microchannels have been fabricated by using a CO{sub 2} laser cutter to pattern microchannels on transparent poly(methyl methacrylate) (PMMA) sheets covered with thermally bonded transparent polyvinyl chloride (PVC) sheets. To examine the performance of the microfluidic magnetic switching valves, an aqueous magnetic nanoparticle suspension was injected into the microchannels by a syringe pump. Neodymium magnets were then employed to attract magnetic nanoparticles and form an aggregate that blocked the microchannels at a required position. We have found that the maximum volumetric flow rate of the syringe pump that the magnetic nanoparticle aggregate can withstand scales with the square of the external magnetic flux density. The viscosity of the fluid exhibits dependent on the aggregate length and the size of the magnetic nanoparticles. This microfluidic switching valve based on aggregates of magnetic nanoparticles has strong potentials as an on-demand flow control, which may help simplifying microfluidic channel designs. - Highlights: • We demonstrate microfluidic switching valves based on aggregates of magnetic particles. • Maximum flow rate that the aggregate can withstand scales with the square of the external magnetic flux density. • Aggregates with smaller magnetic nanoparticle size can withstand higher flow rate. • Aggregate length exhibits a linear dependence with flow resistance of a viscous fluid.

  4. Characterization of Binary Organogels Based on Some Azobenzene Compounds and Alkyloxybenzoic Acids with Different Chain Lengths

    Directory of Open Access Journals (Sweden)

    Yongmei Hu

    2014-01-01

    Full Text Available In this work the gelation behaviors of binary organogels composed of azobenzene amino derivatives and alkyloxybenzoic acids with different lengths of alkyl chains in various organic solvents were investigated and characterized. The corresponding gelation behaviors in 20 solvents were characterized and shown as new binary organic systems. It showed that the lengths of substituent alkyl chains in compounds have played an important role in the gelation formation of gelator mixtures in present tested organic solvents. Longer methylene chains in molecular skeletons in these gelators seem more suitable for the gelation of present solvents. Morphological characterization showed that these gelator molecules have the tendency to self-assemble into various aggregates from lamella, wrinkle, and belt to dot with change of solvents and gelator mixtures. Spectral characterization demonstrated different H-bond formation and hydrophobic force existing in gels, depending on different substituent chains in molecular skeletons. Meanwhile, these organogels can self-assemble to form monomolecular or multilayer nanostructures owing to the different lengths of due to alkyl substituent chains. Possible assembly modes for present xerogels were proposed. The present investigation is perspective to provide new clues for the design of new nanomaterials and functional textile materials with special microstructures.

  5. A PCR-based protocol to accurately size C9orf72 intermediate-length alleles.

    Science.gov (United States)

    Biasiotto, Giorgio; Archetti, Silvana; Di Lorenzo, Diego; Merola, Francesca; Paiardi, Giulia; Borroni, Barbara; Alberici, Antonella; Padovani, Alessandro; Filosto, Massimiliano; Bonvicini, Cristian; Caimi, Luigi; Zanella, Isabella

    2017-04-01

    Although large expansions of the non-coding GGGGCC repeat in C9orf72 gene are clearly defined as pathogenic for Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Lobar Degeneration (FTLD), intermediate-length expansions have also been associated with those and other neurodegenerative diseases. Intermediate-length allele sizing is complicated by intrinsic properties of current PCR-based methodologies, in that somatic mosaicism could be suspected. We designed a protocol that allows the exact sizing of intermediate-length alleles, as well as the identification of large expansions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. The acid-base resistant zone in three dentin bonding systems.

    Science.gov (United States)

    Inoue, Go; Nikaido, Toru; Foxton, Richard M; Tagami, Junji

    2009-11-01

    An acid-base resistant zone has been found to exist after acid-base challenge adjacent to the hybrid layer using SEM. The aim of this study was to examine the acid-base resistant zone using three different bonding systems. Dentin disks were applied with three different bonding systems, and then a resin composite was light-cured to make dentin disk sandwiches. After acid-base challenge, the polished surfaces were observed using SEM. For both one- and two-step self-etching primer systems, an acid-base resistant zone was clearly observed adjacent to the hybrid layer - but with differing appearances. For the wet bonding system, the presence of an acid-base resistant zone was unclear. This was because the self-etching primer systems etched the dentin surface mildly, such that the remaining mineral phase of dentin and the bonding agent yielded clear acid-base resistant zones. In conclusion, the acid-base resistant zone was clearly observed when self-etching primer systems were used, but not so for the wet bonding system.

  7. An Investigation of Bond Strength of Reinforcing Bars in Fly Ash and GGBS Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Boopalan C.

    2017-01-01

    Full Text Available Geopolymers are amorphous aluminosilicate materials. Geopolymers are binders formed by alkali activation of Geopolymer Source Materials (GSM using an alkaline activator solution. Concretes made using Geopolymer binders are excellent alternative to the Ordinary Portland Cement concretes from strength, durability, and ecological considerations. Especially, usage of industrial waste materials such as Fly Ash and Slags as GSMs considerably lower the carbon footprint of concrete and mitigate the damage due to the unscientific dumping/disposal of these materials. To use the Geopolymer concrete (GPC for reinforced structural members, the composite action of reinforcing bars with Geopolymer concrete i.e. the bond behaviour should be well understood. This paper describes the bond behaviour of 12mm and 16mm dia. bars embedded in Fly ash and GGBS based Geopolymer concrete and conventional Portland Pozzolana cement concrete specimens investigated using the pull-out tests as per Indian Standard Code IS:2770(Part-I; the bond stresses and corresponding slips were found out. The bond stress increased with increase in compressive strength. The peak bond stress was found to be 4.3 times more than the design bond stress as per IS:456-2000. The Geopolymer concretes possess higher bond strength compared to the conventional cement concretes.

  8. PMMA to SU-8 bonding for polymer based lab-on-a-chip systems with integrated optics

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Nielsen, Theodor; Clausen, Bjarne Hans

    2004-01-01

    We present an adhesive bonding technique developed for SU-8 based "lab-on-a-chip"- systems with integrated optical components. Microfluidic channels and optical components (e.g. wave-guides) are defined in SU-8 photoresist on a Pyrex glass substrate. The microfluidic channels are sealed by a second...... Pyrex substrate, bonded on top of the cross-linked SU-8 structure using an inter- mediate layer of 950K molecular weight poly-methylmethacrylate (PMMA). Due to a lower refractive index of PMMA, this bonding technique offers optical waveguiding in the SU-8 structures in combination with good sealing...... of the microfluidic channels. The bonding technique is investigated with respect to bonding temperature in the range of 50 - 150 degr. C and at bonding forces of 1000 N and 2000 N on a 4-inch wafer. A maximum bonding strength of 16 MPa is achieved for the PMMA to SU-8 bonding at a bonding temperature of 110 degr. C...

  9. All-optical, thermo-optical path length modulation based on the vanadium-doped fibers.

    Science.gov (United States)

    Matjasec, Ziga; Campelj, Stanislav; Donlagic, Denis

    2013-05-20

    This paper presents an all-fiber, fully-optically controlled, optical-path length modulator based on highly absorbing optical fiber. The modulator utilizes a high-power 980 nm pump diode and a short section of vanadium-co-doped single mode fiber that is heated through absorption and a non-radiative relaxation process. The achievable path length modulation range primarily depends on the pump's power and the convective heat-transfer coefficient of the surrounding gas, while the time response primarily depends on the heated fiber's diameter. An absolute optical length change in excess of 500 µm and a time-constant as short as 11 ms, were demonstrated experimentally. The all-fiber design allows for an electrically-passive and remote operation of the modulator. The presented modulator could find use within various fiber-optics systems that require optical (remote) path length control or modulation.

  10. Threshold Research on Highway Length under Typical Landscape Patterns Based on Drivers’ Physiological Performance

    Directory of Open Access Journals (Sweden)

    Xia Zhao

    2015-01-01

    Full Text Available The appropriately landscaped highway scenes may not only help improve road safety and comfort but also help protect ecological environment. Yet there is very little research data on highway length threshold with consideration of distinctive landscape patterns. Against this backdrop, the paper aims to quantitatively analyze highway landscape’s effect on driving behavior based on drivers’ physiological performance and quantify highway length thresholds under three typical landscape patterns, namely, “open,” “semiopen,” and “vertical” ones. The statistical analysis was based on data collected in a driving simulator and electrocardiograph. Specifically, vehicle-related data, ECG data, and supplemental subjective stress perception were collected. The study extracted two characteristic indices, lane deviation and LF/HF, and extrapolated the drivers’ U-shaped physiological response to landscape patterns. Models on highway length were built based on LF/HF’s variation trend with highway length. The results revealed that the theoretical highway length threshold tended to increase when the landscape pattern was switched to open, semiopen, and vertical ones. And the reliability and accuracy of the results were validated by questionnaires and field operational tests. Findings from this research will assist practitioners in taking active environmental countermeasures pertaining to different roadside landscape patterns.

  11. Dynamic Allan Variance Analysis Method with Time-Variant Window Length Based on Fuzzy Control

    Directory of Open Access Journals (Sweden)

    Shanshan Gu

    2015-01-01

    Full Text Available To solve the problem that dynamic Allan variance (DAVAR with fixed length of window cannot meet the identification accuracy requirement of fiber optic gyro (FOG signal over all time domains, a dynamic Allan variance analysis method with time-variant window length based on fuzzy control is proposed. According to the characteristic of FOG signal, a fuzzy controller with the inputs of the first and second derivatives of FOG signal is designed to estimate the window length of the DAVAR. Then the Allan variances of the signals during the time-variant window are simulated to obtain the DAVAR of the FOG signal to describe the dynamic characteristic of the time-varying FOG signal. Additionally, a performance evaluation index of the algorithm based on radar chart is proposed. Experiment results show that, compared with different fixed window lengths DAVAR methods, the change of FOG signal with time can be identified effectively and the evaluation index of performance can be enhanced by 30% at least by the DAVAR method with time-variant window length based on fuzzy control.

  12. Estimation of the flow resistances exerted in coronary arteries using a vessel length-based method.

    Science.gov (United States)

    Lee, Kyung Eun; Kwon, Soon-Sung; Ji, Yoon Cheol; Shin, Eun-Seok; Choi, Jin-Ho; Kim, Sung Joon; Shim, Eun Bo

    2016-08-01

    Flow resistances exerted in the coronary arteries are the key parameters for the image-based computer simulation of coronary hemodynamics. The resistances depend on the anatomical characteristics of the coronary system. A simple and reliable estimation of the resistances is a compulsory procedure to compute the fractional flow reserve (FFR) of stenosed coronary arteries, an important clinical index of coronary artery disease. The cardiac muscle volume reconstructed from computed tomography (CT) images has been used to assess the resistance of the feeding coronary artery (muscle volume-based method). In this study, we estimate the flow resistances exerted in coronary arteries by using a novel method. Based on a physiological observation that longer coronary arteries have more daughter branches feeding a larger mass of cardiac muscle, the method measures the vessel lengths from coronary angiogram or CT images (vessel length-based method) and predicts the coronary flow resistances. The underlying equations are derived from the physiological relation among flow rate, resistance, and vessel length. To validate the present estimation method, we calculate the coronary flow division over coronary major arteries for 50 patients using the vessel length-based method as well as the muscle volume-based one. These results are compared with the direct measurements in a clinical study. Further proving the usefulness of the present method, we compute the coronary FFR from the images of optical coherence tomography.

  13. New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

    Directory of Open Access Journals (Sweden)

    Pavel Nagorny

    2016-12-01

    Full Text Available Hydrogen bond donor catalysis represents a rapidly growing subfield of organocatalysis. While traditional hydrogen bond donors containing N–H and O–H moieties have been effectively used for electrophile activation, activation based on other types of non-covalent interactions is less common. This mini review highlights recent progress in developing and exploring new organic catalysts for electrophile activation through the formation of C–H hydrogen bonds and C–X halogen bonds.

  14. Emergency Department Length of Stay for Critical Care Admissions. A Population-based Study.

    Science.gov (United States)

    Rose, Louise; Scales, Damon C; Atzema, Clare; Burns, Karen E A; Gray, Sara; Doing, Christina; Kiss, Alex; Rubenfeld, Gordon; Lee, Jacques S

    2016-08-01

    Hospital emergency department (ED) strain is common in North America. Excessive strain may result in prolonged ED length of stay and may lead to worse outcomes for patients admitted to intensive care units (ICUs). To describe patient, ED, and hospital characteristics associated with prolonged ED length of stay for adult patients admitted from EDs to ICUs. We conducted a population-based cohort study in the Province of Ontario, Canada, including patients admitted to an adult ICU from an ED and excluding only interhospital transfers and scheduled visits. Using regression modeling, we examined associations between patient- and hospital-level characteristics and two ED performance measures: length of stay in the ED of more than 6 hours and 90-day mortality. From April 2007 to March 2012, 261,274 adults presented to 118 EDs in Ontario, generating 314,836 ICU admissions. This activity represented 4.1% of all adult ED visits (incidence, 1,374 ICU admissions/100,000 ED visits). Median (interquartile range) ED length of stay was 7 (4-13) hours. Less than half (41.4%; 95% confidence interval [CI], 41.2-41.5) of these patients had an ED length of stay of 6 hours or less, whereas 10.5% (95% CI, 10.4-10.6) stayed 24 hours or longer. Hospital characteristics associated with ED length of stay more than 6 hours included shift-level ED crowding (mean length of stay of patients of similar acuity registering during same 8 h epoch) (odds ratio [OR], 1.19/h; 95% CI, 1.19-1.19), ED annual visit volume (OR, 1.01/1,000 patients; 95% CI, 1.01-1.01), time of ED presentation (00:00-07:59) (OR, 1.41; 95% CI, 1.38-1.45), and ICU functioning at greater than 20% above the average annual census (OR, 1.10; 95% CI, 1.08-1.12). ED length of stay more than 6 hours was not associated with 90-day mortality after adjustment for selected confounders (OR, 0.99; 95% CI, 0.97-1.02). In this population-based study, less than half of adult ED patients were admitted to an ICU 6 hours or less after arrival to

  15. A quality quantitative method of silicon direct bonding based on wavelet image analysis

    Science.gov (United States)

    Tan, Xiao; Tao, Zhi; Li, Haiwang; Xu, Tiantong; Yu, Mingxing

    2018-04-01

    The rapid development of MEMS (micro-electro-mechanical systems) has received significant attention from researchers in various fields and subjects. In particular, the MEMS fabrication process is elaborate and, as such, has been the focus of extensive research inquiries. However, in MEMS fabrication, component bonding is difficult to achieve and requires a complex approach. Thus, improvements in bonding quality are relatively important objectives. A higher quality bond can only be achieved with improved measurement and testing capabilities. In particular, the traditional testing methods mainly include infrared testing, tensile testing, and strength testing, despite the fact that using these methods to measure bond quality often results in low efficiency or destructive analysis. Therefore, this paper focuses on the development of a precise, nondestructive visual testing method based on wavelet image analysis that is shown to be highly effective in practice. The process of wavelet image analysis includes wavelet image denoising, wavelet image enhancement, and contrast enhancement, and as an end result, can display an image with low background noise. In addition, because the wavelet analysis software was developed with MATLAB, it can reveal the bonding boundaries and bonding rates to precisely indicate the bond quality at all locations on the wafer. This work also presents a set of orthogonal experiments that consist of three prebonding factors, the prebonding temperature, the positive pressure value and the prebonding time, which are used to analyze the prebonding quality. This method was used to quantify the quality of silicon-to-silicon wafer bonding, yielding standard treatment quantities that could be practical for large-scale use.

  16. State of the science of maternal-infant bonding: a principle-based concept analysis.

    Science.gov (United States)

    Bicking Kinsey, Cara; Hupcey, Judith E

    2013-12-01

    to provide a principle-based analysis of the concept of maternal-infant bonding. principle-based method of concept analysis for which the data set included 44 articles published in the last decade from Pubmed, CINAHL, and PyschINFO/PsychARTICLES. literature inclusion criteria were English language, articles published in the last decade, peer-reviewed journal articles and commentary on published work, and human populations. after a brief review of the history of maternal-infant bonding, a principle-based concept analysis was completed to examine the state of the science with regard to this concept. The concept was critically examined according to the clarity of definition (epistemological principle), applicability of the concept (pragmatic principle), consistency in use and meaning (linguistic principle), and differentiation of the concept from related concepts (logical principle). Analysis of the concept revealed: (1) Maternal-infant bonding describes maternal feelings and emotions towards her infant. Evidence that the concept encompasses behavioural or biological components was limited. (2) The concept is clearly operationalised in the affective domain. (3) Maternal-infant bonding is linguistically confused with attachment, although the boundaries between the concepts are clearly delineated. despite widespread use of the concept, maternal-infant bonding is at times superficially developed and subject to confusion with related concepts. Concept clarification is warranted. A theoretical definition of the concept of maternal-infant bonding was developed to aid in the clarification, but more research is necessary to further clarify and advance the concept. nurse midwives and other practitioners should use the theoretical definition of maternal-infant bonding as a preliminary guide to identification and understanding of the concept in clinical practice. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Improved water resistance of bio-based adhesives for wood bonding

    Science.gov (United States)

    Charles R. Frihart; James M. Wescott

    2004-01-01

    Synthetic resins, such as phenol-formaldehyde (PF), are dominant in wood bonding for exterior and semi-exterior applications because of their excellent water resistance. Replacement of petroleum-based resins with ones having high biomass content would further enhance the environmental preferability of reconstituted wood-based materials. Past studies on using soybean...

  18. Research On Variable-Length Transfer Delay and Delayed Signal Cancellation Based PLLs

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2018-01-01

    large frequency drifts are anticipated and a high accuracy is required. To the best of authors' knowledge, the small-signal modeling of a variable-length delay-based PLL has not yet been conducted. The main aim of this paper is to cover this gap. The tuning procedure and analysis of these PLLs...

  19. Experimental investigation of halogen-bond hard-soft acid-base complementarity.

    Science.gov (United States)

    Riel, Asia Marie S; Jessop, Morly J; Decato, Daniel A; Massena, Casey J; Nascimento, Vinicius R; Berryman, Orion B

    2017-04-01

    The halogen bond (XB) is a topical noncovalent interaction of rapidly increasing importance. The XB employs a `soft' donor atom in comparison to the `hard' proton of the hydrogen bond (HB). This difference has led to the hypothesis that XBs can form more favorable interactions with `soft' bases than HBs. While computational studies have supported this suggestion, solution and solid-state data are lacking. Here, XB soft-soft complementarity is investigated with a bidentate receptor that shows similar associations with neutral carbonyls and heavy chalcogen analogs. The solution speciation and XB soft-soft complementarity is supported by four crystal structures containing neutral and anionic soft Lewis bases.

  20. Characterization of wood-based molding bonded with citric acid

    OpenAIRE

    Umemura, Kenji; Ueda, Tomohide; Kawai, Shuichi

    2012-01-01

    The wood-based moldings were fabricated by using only citric acid as an adhesive. The mechanical properties, water resistances, thermal properties and chemical structure were investigated. Wood powder obtained from Acacia mangium was mixed with citric acid under certain weight ratios (0-40 wt%), and each powder mixture was molded using two types of metal molds at 200 °C and 4MPa for 10 min. The modulus of rupture (MOR) and the modulus of elasticity (MOE) values of the wood-based molding conta...

  1. Node Detection and Internode Length Estimation of Tomato Seedlings Based on Image Analysis and Machine Learning

    Directory of Open Access Journals (Sweden)

    Kyosuke Yamamoto

    2016-07-01

    Full Text Available Seedling vigor in tomatoes determines the quality and growth of fruits and total plant productivity. It is well known that the salient effects of environmental stresses appear on the internode length; the length between adjoining main stem node (henceforth called node. In this study, we develop a method for internode length estimation using image processing technology. The proposed method consists of three steps: node detection, node order estimation, and internode length estimation. This method has two main advantages: (i as it uses machine learning approaches for node detection, it does not require adjustment of threshold values even though seedlings are imaged under varying timings and lighting conditions with complex backgrounds; and (ii as it uses affinity propagation for node order estimation, it can be applied to seedlings with different numbers of nodes without prior provision of the node number as a parameter. Our node detection results show that the proposed method can detect 72% of the 358 nodes in time-series imaging of three seedlings (recall = 0.72, precision = 0.78. In particular, the application of a general object recognition approach, Bag of Visual Words (BoVWs, enabled the elimination of many false positives on leaves occurring in the image segmentation based on pixel color, significantly improving the precision. The internode length estimation results had a relative error of below 15.4%. These results demonstrate that our method has the ability to evaluate the vigor of tomato seedlings quickly and accurately.

  2. Detection of an amphiphilic biosample in a paper microchannel based on length.

    Science.gov (United States)

    Chen, Yu-Tzu; Yang, Jing-Tang

    2015-01-01

    We developed a simple method to achieve semiquantitative detection of an amphiphilic biosample through measuring the length of flow on a microfluidic analytical device (μPAD) based on paper. When an amphiphilic sample was dripped into a straight microchannel defined with a printed wax barrier (hydrophobic) on filter paper (hydrophilic), the length of flow was affected by the reciprocal effect between the sample, the filter-paper channel and the wax barrier. The flow length decreased with increasing concentration of an amphiphilic sample because of adsorption of the sample on the hydrophobic barrier. Measurement of the flow length enabled a determination of the concentration of the amphiphilic sample. The several tested samples included surfactants (Tween 20 and Triton X-100), oligonucleotides (DNA), bovine serum albumin (BSA), human albumin, nitrite, glucose and low-density lipoprotein (LDL). The results show that the measurement of the flow length determined directly the concentration of an amphiphilic sample, whereas a non-amphiphilic sample was not amenable to this method. The proposed method features the advantages of small cost, simplicity, convenience, directness, rapidity (<5 min) and requirement of only a small volume (5 μL) of sample, with prospective applications in developing areas and sites near patients for testing at a point of care (POCT).

  3. Determination of Wind Turbine Near-Wake Length Based on Stability Analysis

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming; Sarmast, Sasan

    2014-01-01

    A numerical study on the wake behind a wind turbine is carried out focusing on determining the length of the near-wake based on the instability onset of the trailing tip vortices shed from the turbine blades. The numerical model is based on large-eddy simulations (LES) of the Navier-Stokes equati......A numerical study on the wake behind a wind turbine is carried out focusing on determining the length of the near-wake based on the instability onset of the trailing tip vortices shed from the turbine blades. The numerical model is based on large-eddy simulations (LES) of the Navier...... of the study it is found that the amplification of specific waves (traveling structures) along the tip vortex spirals is responsible for triggering the instability leading to wake breakdown. The presence of unstable modes in the wake is related to the mutual inductance (vortex pairing) instability where...

  4. Intramolecular hydrogen bonding and tautomerism in Schiff bases ...

    Indian Academy of Sciences (India)

    Administrator

    C NMR, DEPT and aided by 2D HETCOR and HMBC heteronuclear correlation techniques. The UV-vis spectra of the Schiff bases have been systematically studied in organic solvents of different polarity, acidic and basic media and found useful in understanding of tautomeric equilibria (phenol-imine, O–H...N and ...

  5. Modal Analysis of In-Wheel Motor-Driven Electric Vehicle Based on Bond Graph Theory

    Directory of Open Access Journals (Sweden)

    Di Tan

    2017-01-01

    Full Text Available A half-car vibration model of an electric vehicle driven by rear in-wheel motors was developed using bond graph theory and the modular modeling method. Based on the bond graph model, modal analysis was carried out to study the vibration characteristics of the electric vehicle. To verify the effectiveness of the established model, the results were compared to ones computed on the ground of modal analysis and Newton equations. The comparison shows that the vibration model of the electric vehicle based on bond graph theory not only is able to better compute the natural frequency but also can easily determine the deformation mode, momentum mode, and other isomorphism modes and describe the dynamic characteristics of an electric vehicle driven by in-wheel motors more comprehensively than other modal analysis methods.

  6. Thin and thick layers of resin-based sealer cement bonded to root dentine compared: Adhesive behaviour.

    Science.gov (United States)

    Pane, Epita S; Palamara, Joseph E A; Messer, Harold H

    2015-12-01

    This study aims to evaluate tensile and shear bond strengths of one epoxy (AH) and two methacrylate resin-based sealers (EZ and RS) in thin and thick layers bonded to root dentine. An alignment device was prepared for accurate positioning of 20 root dentine cylinders in a predefined gap of 0.1 or 1 mm. Sealer was placed in the interface. Bond strength tests were conducted. Mode of failures and representative surfaces were evaluated. Data were analysed using anova and post-hoc tests, with P thick layer of sealer produced higher bond strength, except for the shear bond strength of EZ. Significant differences between thin and thick layers were found only in tensile bond strengths of AH and RS. Mixed type of failure was constantly found with all sealers. Bond strengths of thick layers of resin-based sealers to root dentine tended to be higher than with thin layers. © 2015 Australian Society of Endodontology.

  7. Pricing index-based catastrophe bonds: Part 2: Object-oriented design issues and sensitivity analysis

    Science.gov (United States)

    Unger, André J. A.

    2010-02-01

    This work is the second installment in a two-part series, and focuses on object-oriented programming methods to implement an augmented-state variable approach to aggregate the PCS index and introduce the Bermudan-style call feature into the proposed CAT bond model. The PCS index is aggregated quarterly using a discrete Asian running-sum formulation. The resulting aggregate PCS index augmented-state variable is used to specify the payoff (principle) on the CAT bond based on reinsurance layers. The purpose of the Bermudan-style call option is to allow the reinsurer to minimize their interest rate risk exposure on making fixed coupon payments under prevailing interest rates. A sensitivity analysis is performed to determine the impact of uncertainty in the frequency and magnitude of hurricanes on the price of the CAT bond. Results indicate that while the CAT bond is highly sensitive to the natural variability in the frequency of landfalling hurricanes between El Ninõ and non-El Ninõ years, it remains relatively insensitive to uncertainty in the magnitude of damages. In addition, results indicate that the maximum price of the CAT bond is insensitive to whether it is engineered to cover low frequency high magnitude events in a 'high' reinsurance layer relative to high frequency low magnitude events in a 'low' reinsurance layer. Also, while it is possible for the reinsurer to minimize their interest rate risk exposure on the fixed coupon payments, the impact of this risk on the price of the CAT bond appears small relative to the natural variability in the CAT bond price, and consequently catastrophic risk, due to uncertainty in the frequency and magnitude of landfalling hurricanes.

  8. Spherical aberration compensation method for long focal-length measurement based on Talbot interferometry

    Science.gov (United States)

    Luo, Yupeng; Huang, Xiao; Bai, Jian; Du, Juan; Liu, Qun; Luo, Yujie; Luo, Jia

    2017-08-01

    Large-aperture and long focal-length lens is widely used in high energy laser system. The method based on Talbot interferometry is a reliable method to measure the focal length of such elements. By employing divergent beam and two gratings of different periods, this method could realize full-aperture measurement, higher accuracy and better repeatability. However, it does not take into account the spherical aberration of the measured lens resulting in the moiré fringes bending, which will introduce measurement error. Furthermore, in long-focal measurement with divergent beam, this error is an important factor affecting the measurement accuracy. In this paper, we propose a new spherical aberration compensation method, which could significantly reduce the measurement error. Characterized by central-symmetric scanning window, the proposed method is based on the relationship between spherical aberration and the lens aperture. Angle data of moiré fringes in each scanning window is retrieved by Fourier analysis and statistically fitted to estimate a globally optimum value for spherical-aberration-free focal length calculation. Simulation and experiment have been carried out. Compared to the previous work, the proposed method is able to reduce the relative measurement error by 50%. The effect of scanning window size and shift step length on the results is also discussed.

  9. 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.

  10. Area-based initiatives – and their work in bonding, bridging and linking social capital

    DEFF Research Database (Denmark)

    Agger, Annika; Jensen, Jesper Ole

    2015-01-01

    In this article, we provide a conceptual and argumentative framework for studying how Area-based Initiatives (ABIs) can facilitate contact between networks in deprived neighbourhoods and external forms of power (linking social capital). These relations provide the residents and other members...... of social capital (bridging, bonding and linking). The article concludes that ABIs contribute to creating linking social capital, but the extent of the contribution depends on the level of bonding and bridging social capital in the area. We argue that public planners as well as evaluators of the ABIs should...

  11. Watson-Crick base pairs with thiocarbonyl groups: How sulfur changes the hydrogen bonds in DNA

    NARCIS (Netherlands)

    Fonseca Guerra, C.; Baerends, E.J.; Bickelhaupt, F.M.

    2008-01-01

    We have theoretically analyzed mimics of Watson-Crick AT and GC base pairs in which N-H•••O hydrogen bonds are replaced by N-H•••S, using the generalized gradient approximation (GGA) of density functional theory at BP86/TZ2P level. The general effect of the above substitutions is an elongation and a

  12. Properties and shaping of lightweight ceramics based on phosphate-bonded hollow silica microspheres

    NARCIS (Netherlands)

    With, de G.; Verweij, H.

    1986-01-01

    The values for the Young's modulus, strength, fracture toughness and thermal conductivity of lightweight ceramics based on phosphate-bonded hollow silica microspheres are reported as a function of the processing conditions. They are compared with the relevant data for other lightweight ceramic

  13. Novel indole-based inhibitors of IMPDH: introduction of hydrogen bond acceptors at indole C-3.

    Science.gov (United States)

    Watterson, Scott H; Dhar, T G Murali; Ballentine, Shelley K; Shen, Zhongqi; Barrish, Joel C; Cheney, Daniel; Fleener, Catherine A; Rouleau, Katherine A; Townsend, Robert; Hollenbaugh, Diane L; Iwanowicz, Edwin J

    2003-04-07

    The development of a series of novel indole-based inhibitors of 5'-inosine monophosphate dehydrogenase (IMPDH) is described. Various hydrogen bond acceptors at C-3 of the indole were explored. The synthesis and the structure-activity relationships (SARs) derived from in vitro studies are outlined.

  14. Shear bond strength of a denture base acrylic resin and gingiva-colored indirect composite material to zirconia ceramics.

    Science.gov (United States)

    Kubochi, Kei; Komine, Futoshi; Fushiki, Ryosuke; Yagawa, Shogo; Mori, Serina; Matsumura, Hideo

    2017-04-01

    To evaluate the shear bond strengths of two gingiva-colored materials (an indirect composite material and a denture base acrylic resin) to zirconia ceramics and determine the effects of surface treatment with various priming agents. A gingiva-colored indirect composite material (CER) or denture base acrylic resin (PAL) was bonded to zirconia disks with unpriming (UP) or one of seven priming agents (n=11 each), namely, Alloy Primer (ALP), Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Act), Metal Link (MEL), Meta Fast Bonding Liner (MFB), MR. bond (MRB), and V-Primer (VPR). Shear bond strength was determined before and after 5000 thermocycles. The data were analyzed with the Kruskal-Wallis test and Steel-Dwass test. The mean pre-/post-thermalcycling bond strengths were 1.0-14.1MPa/0.1-12.1MPa for the CER specimen and 0.9-30.2MPa/0.1-11.1MPa for the PAL specimen. For the CER specimen, the ALP, CPB, and CPB+Act groups had significantly higher bond strengths among the eight groups, at both 0 and 5000 thermocycles. For the PAL specimen, shear bond strength was significantly lower after thermalcycling in all groups tested. After 5000 thermocycles, bond strengths were significantly higher in the CPB and CPB+Act groups than in the other groups. For the PAL specimens, bond strengths were significantly lower after thermalcycling in all groups tested. The MDP functional monomer improved bonding of a gingiva-colored indirect composite material and denture base acrylic resin to zirconia ceramics. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  15. Transient liquid phase bonding of titanium-, iron- and nickel-based alloys

    Science.gov (United States)

    Rahman, A. H. M. Esfakur

    The operating temperature of land-based gas turbines and jet engines are ever-increasing to increase the efficiency, decrease the emissions and minimize the cost. Within the engines, complex-shaped parts experience extreme temperature, fatigue and corrosion conditions. Ti-based, Ni-based and Fe-based alloys are commonly used in gas turbines and jet engines depending on the temperatures of different sections. Although those alloys have superior mechanical, high temperature and corrosion properties, severe operating conditions cause fast degradation and failure of the components. Repair of these components could reduce lifecycle costs. Unfortunately, conventional fusion welding is not very attractive, because Ti reacts very easily with oxygen and nitrogen at high temperatures, Ni-based superalloys show heat affected zone (HAZ) cracking, and stainless steels show intergranular corrosion and knife-line attack. On the other hand, transient liquid phase (TLP) bonding method has been considered as preferred joining method for those types of alloys. During the initial phase of the current work commercially pure Ti, Fe and Ni were diffusion bonded using commercially available interlayer materials. Commercially pure Ti (Ti-grade 2) has been diffusion bonded using silver and copper interlayers and without any interlayer. With a silver (Ag) interlayer, different intermetallics (AgTi, AgTi2) appeared in the joint centerline microstructure. While with a Cu interlayer eutectic mixtures and Ti-Cu solid solutions appeared in the joint centerline. The maximum tensile strengths achieved were 160 MPa, 502 MPa, and 382 MPa when Ag, Cu and no interlayers were used, respectively. Commercially pure Fe (cp-Fe) was diffusion bonded using Cu (25 m) and Au-12Ge eutectic interlayer (100 microm). Cu diffused predominantly along austenite grain boundaries in all bonding conditions. Residual interlayers appeared at lower bonding temperature and time, however, voids were observed in the joint

  16. In vitro comparison of the tensile bond strength of denture adhesives on denture bases.

    Science.gov (United States)

    Kore, Doris R; Kattadiyil, Mathew T; Hall, Dan B; Bahjri, Khaled

    2013-12-01

    With several denture adhesives available, it is important for dentists to make appropriate patient recommendations. The purpose of this study was to evaluate the tensile bond strength of denture adhesives on denture base materials at time intervals of up to 24 hours. Fixodent, Super Poligrip, Effergrip, and SeaBond denture adhesives were tested with 3 denture base materials: 2 heat-polymerized (Lucitone 199 and SR Ivocap) and 1 visible-light-polymerized (shade-stable Eclipse). Artificial saliva with mucin was used as a control. Tensile bond strength was tested in accordance with American Dental Association specifications at 5 minutes, 3 hours, 6 hours, 12 hours, and 24 hours after applying the adhesive. Maximum forces before failure were recorded in megapascals (MPa), and the data were subjected to a 2-way analysis of variance (α=.05). All 4 adhesives had greater tensile bond strength than the control. Fixodent, Super Poligrip, and SeaBond had higher tensile bond strength values than Effergrip. All adhesives had the greatest tensile bond strength at 5 minutes and the least at 24 hours. The 3 denture bases produced significantly different results with each adhesive (Padhesives had the greatest tensile bond strength, followed by Ivocap and Eclipse. All 4 adhesives had greater tensile bond strength than the control, and all 4 adhesives were strongest at the 5-minute interval. On all 3 types of denture bases, Effergrip produced significantly lower tensile bond strength, and Fixodent, Super Poligrip, and SeaBond produced significantly higher tensile bond strength. At 24 hours, the adhesive-base combinations with the highest tensile bond strength were Fixodent on Lucitone 199, Fixodent on Eclipse, Fixodent on Ivocap, and Super Poligrip on Ivocap. Copyright © 2013 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  17. PMMA to SU-8 Bonding for Polymer Based Lab-on-a-chip Systems with Integrated Optics

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Nielsen, Theodor; Nilsson, Daniel

    2003-01-01

    An adhesive bonding technique for wafer-level sealing of SU-8 based lab-on-a-chip microsystems with integrated optical components is presented. Microfluidic channels and optical components, e.g. waveguides, are fabricated in cross-linked SU-8 and sealed with a Pyrex glass substrate by means...... strength of 16 MPa is achieved at bonding temperatures between 110 oC and 120oC, at a bonding force of 2000 N on a 4-inch wafer. The optical propagation loss of multi-mode 10ym (thickness)x 30ym (width)SU-8 waveguides is measured. The propagation loss in PMMA bonded waveguide struc-tures is more than 5 d......B/cm lower, at wavelengths between 600nm and 900 nm, than in similar structures bonded by an intermediate layer of SU-8. Furthermore 950K PMMA shows no tendency to flow into the bonded structures during bonding because of its high viscosity....

  18. The association between intelligence and telomere length: a longitudinal population based study.

    Directory of Open Access Journals (Sweden)

    Eva M Kingma

    Full Text Available Low intelligence has been associated with poor health and mortality, but underlying mechanisms remain obscure. We hypothesized that low intelligence is associated with accelerated biological ageing as reflected by telomere length; we suggested potential mediation of this association by unhealthy behaviors and low socioeconomic position. The study was performed in a longitudinal population-based cohort study of 895 participants (46.8% males. Intelligence was measured with the Generalized Aptitude-Test Battery at mean age 52.8 years (33-79 years, SD=11.3. Leukocyte telomere length was measured by PCR. Lifestyle and socioeconomic factors were assessed using written self-report measures. Linear regression analyses, adjusted for age, sex, and telomere length measured at the first assessment wave (T1, showed that low intelligence was associated with shorter leukocyte telomere length at approximately 2 years follow-up (beta= .081, t=2.160, p= .031. Nearly 40% of this association was explained by an unhealthy lifestyle, while low socioeconomic position did not add any significant mediation. Low intelligence may be a risk factor for accelerated biological ageing, thereby providing an explanation for its association with poor health and mortality.

  19. Flip-chip bonded optoelectronic integration based on ultrathin silicon (UTSi) CMOS

    Science.gov (United States)

    Hong, Sunkwang; Ho, Tawei; Zhang, Liping; Sawchuk, Alexander A.

    2003-06-01

    We describe the design and test of flip-chip bonded optoelectronic CMOS devices based on Peregrine Semiconductor's 0.5 micron Ultra-Thin Silicon on sapphire (UTSi) technology. The UTSi process eliminates the substrate leakage that typically results in crosstalk and reduces parasitic capacitance to the substrate, providing many benefits compared to bulk silicon CMOS. The low-loss synthetic sapphire substrate is optically transparent and has a coefficient of thermal expansion suitable for flip-chip bonding of vertical cavity surface emitting lasers (VCSELs) and detectors. We have designed two different UTSi CMOS chips. One contains a flip-chip bonded 1 x 4 photodiode array, a receiver array, a double edge triggered D-flip flop-based 2047-pattern pseudo random bit stream (PRBS) generator and a quadrature-phase LC-voltage controlled oscillator (VCO). The other chip contains a flip-chip bonded 1 x 4 VCSEL array, a driver array based on high-speed low-voltage differential signals (LVDS) and a full-balanced differential LC-VCO. Each VCSEL driver and receiver has individual input and bias voltage adjustments. Each UTSi chip is mounted on different printed circuit boards (PCBs) which have holes with about 1 mm radius for optical output and input paths through the sapphire substrate. We discuss preliminary testing of these chips.

  20. Flexure mechanism-based parallelism measurements for chip-on-glass bonding

    International Nuclear Information System (INIS)

    Jung, Seung Won; Yun, Won Soo; Jin, Songwan; Jeong, Young Hun; Kim, Bo Sun

    2011-01-01

    Recently, liquid crystal displays (LCDs) have played vital roles in a variety of electronic devices such as televisions, cellular phones, and desktop/laptop monitors because of their enhanced volume, performance, and functionality. However, there is still a need for thinner LCD panels due to the trend of miniaturization in electronic applications. Thus, chip-on-glass (COG) bonding has become one of the most important aspects in the LCD panel manufacturing process. In this study, a novel sensor was developed to measure the parallelism between the tooltip planes of the bonding head and the backup of the COG main bonder, which has previously been estimated by prescale pressure films in industry. The sensor developed in this study is based on a flexure mechanism, and it can measure the total pressing force and the inclination angles in two directions that satisfy the quantitative definition of parallelism. To improve the measurement accuracy, the sensor was calibrated based on the estimation of the total pressing force and the inclination angles using the least-squares method. To verify the accuracy of the sensor, the estimation results for parallelism were compared with those from prescale pressure film measurements. In addition, the influence of parallelism on the bonding quality was experimentally demonstrated. The sensor was successfully applied to the measurement of parallelism in the COG-bonding process with an accuracy of more than three times that of the conventional method using prescale pressure films

  1. INS/EKF-based stride length, height and direction intent detection for walking assistance robots.

    Science.gov (United States)

    Brescianini, Dario; Jung, Jun-Young; Jang, In-Hun; Park, Hyun Sub; Riener, Robert

    2011-01-01

    We propose an algorithm used to obtain the information on stride length, height difference, and direction based on user's intent during walking. For exoskeleton robots used to assist paraplegic patients' walking, this information is used to generate gait patterns by themselves in on-line. To obtain this information, we attach an inertial measurement unit(IMU) on crutches and apply an extended kalman filter-based error correction method to reduce the phenomena of drift due to bias of the IMU. The proposed method is verifed in real walking scenarios including walking, climbing up-stairs, and changing direction of walking with normal. © 2011 IEEE

  2. [Preliminary study of bonding strength between diatomite-based dental ceramic and veneering porcelains].

    Science.gov (United States)

    Lu, Xiao-li; Gao, Mei-qin; Cheng, Yu-ye; Zhang, Fei-min

    2015-04-01

    In order to choose the best veneering porcelain for diatomite-based dental ceramic substrate, the bonding strength between diatomite-based dental ceramics and veneering porcelains was measured, and the microstructure and elements distribution of interface were analyzed. The coefficient of thermal expansion (CTE) of diatomite-based dental ceramics was detected by dilatometry. Three veneering porcelain materials were selected with the best CTE matching including alumina veneering porcelain (group A), titanium porcelain veneering porcelain (group B), and E-max veneering porcelain (group C). Shear bonding strength was detected. SEM and EDS were used to observe the interface microstructure and element distribution. Statistical analysis was performed using SPSS 17.0 software package. The CTE of diatomite-based dental ceramics at 25-500 degrees centigrade was 8.85×10-6K-1. The diatomite-based substrate ceramics combined best with group C. Shear bonding strength between group A and C and group B and C both showed significant differences(P<0.05). SEM and EDS showed that the interface of group C sintered tightly and elements permeated on both sides of the interface. The diatomite-based substrate ceramics combines better with E-max porcelain veneer.

  3. Feedback Linearization Based Arc Length Control for Gas Metal Arc Welding

    DEFF Research Database (Denmark)

    Thomsen, Jesper Sandberg

    2005-01-01

    a linear system to be controlled by linear state feedback control. The advantage of using a nonlinear approach as feedback linearization is the ability of this method to cope with nonlinearities and different operating points. However, the model describing the GMAW process is not exact, and therefore......In this paper a feedback linearization based arc length controller for gas metal arc welding (GMAW) is described. A nonlinear model describing the dynamic arc length is transformed into a system where nonlinearities can be cancelled by a nonlinear state feedback control part, and thus, leaving only......, the cancellation of nonlinear terms might give rise to problems with respect to robustness. Robustness of the closed loop system is therefore nvestigated by simulation....

  4. 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.

  5. Determination of Wind Turbine Near-Wake Length Based on Stability Analysis

    International Nuclear Information System (INIS)

    Sørensen, Jens N; Mikkelsen, Robert; Sarmast, Sasan; Ivanell, Stefan; Henningson, Dan

    2014-01-01

    A numerical study on the wake behind a wind turbine is carried out focusing on determining the length of the near-wake based on the instability onset of the trailing tip vortices shed from the turbine blades. The numerical model is based on large-eddy simulations (LES) of the Navier-Stokes equations using the actuator line (ACL) method. The wake is perturbed by applying stochastic or harmonic excitations in the neighborhood of the tips of the blades. The flow field is then analyzed to obtain the stability properties of the tip vortices in the wake of the wind turbine. As a main outcome of the study it is found that the amplification of specific waves (traveling structures) along the tip vortex spirals is responsible for triggering the instability leading to wake breakdown. The presence of unstable modes in the wake is related to the mutual inductance (vortex pairing) instability where there is an out-of-phase displacement of successive helix turns. Furthermore, using the non-dimensional growth rate, it is found that the pairing instability has a universal growth rate equal to π/2. Using this relationship, and the assumption that breakdown to turbulence occurs once a vortex has experienced sufficient growth, we provide an analytical relationship between the turbulence intensity and the stable wake length. The analysis leads to a simple expression for determining the length of the near wake. This expression shows that the near wake length is inversely proportional to thrust, tip speed ratio and the logarithmic of the turbulence intensity

  6. Refining Lane-Based Traffic Signal Settings to Satisfy Spatial Lane Length Requirements

    Directory of Open Access Journals (Sweden)

    Yanping Liu

    2017-01-01

    Full Text Available In conventional lane-based signal optimization models, lane markings guiding road users in making turns are optimized with traffic signal settings in a unified framework to maximize the overall intersection capacity or minimize the total delay. The spatial queue requirements of road lanes should be considered to avoid overdesigns of green durations. Point queue system adopted in the conventional lane-based framework causes overflow in practice. Based on the optimization results from the original lane-based designs, a refinement is proposed to enhance the lane-based settings to ensure that spatial holding limits of the approaching traffic lanes are not exceeded. A solution heuristic is developed to modify the green start times, green durations, and cycle length by considering the vehicle queuing patterns and physical holding capacities along the approaching traffic lanes. To show the effectiveness of this traffic signal refinement, a case study of one of the busiest and most complicated intersections in Hong Kong is given for demonstration. A site survey was conducted to collect existing traffic demand patterns and existing traffic signal settings in peak periods. Results show that the proposed refinement method is effective to ensure that all vehicle queue lengths satisfy spatial lane capacity limits, including short lanes, for daily operation.

  7. An Alternative Cu-Based Bond Layer for Electric Arc Coating Process

    Science.gov (United States)

    Fadragas, Carlos R.; Morales, E. V.; Muñoz, J. A.; Bott, I. S.; Lariot Sánchez, C. A.

    2011-12-01

    A Cu-Al alloy has been used as bond coat between a carbon steel substrate and a final coating deposit obtained by applying the twin wire electric arc spraying coating technique. The presence of a copper-based material in the composite system can change the overall temperature profile during deposition because copper exhibits a thermal conductivity several times higher than that of the normally recommended bond coat materials (such as nickel-aluminum alloys or nickel-chromium alloys). The microstructures of 420 and 304 stainless steels deposited by the electric arc spray process have been investigated, focusing attention on the deposit homogeneity, porosity, lamellar structure, and microhardness. The nature of the local temperature gradient during deposition can strongly influence the formation of the final coating deposit. This study presents a preliminary study, undertaken to investigate the changes in the temperature profile which occur when a Cu-Al alloy is used as bond coat, and the possible consequences of these changes on the microstructure and adhesion of the final coating deposit. The influence of the thickness of the bond layer on the top coating temperature has also been also evaluated.

  8. Observation of H-bond mediated 3hJH2H3coupling constants across Watson-Crick AU base pairs in RNA

    International Nuclear Information System (INIS)

    Luy, Burkhard; Richter, Uwe; DeJong, Eric S.; Sorensen, Ole W.; Marino, John P.

    2002-01-01

    3h J H2H3 trans-hydrogen bond scalar coupling constants have been observed for the first time in Watson-Crick AU base pairs in uniformly 15 N-labeled RNA oligonucleotides using a new 2h J NN -HNN-E. COSY experiment. The experiment utilizes adenosine H2 (AH2) for original polarization and detection, while employing 2h J NN couplings for coherence transfer across the hydrogen bonds (H-bonds). The H3 protons of uracil bases are unperturbed throughout the experiment so that these protons appear as passive spins in E. COSY patterns. 3h J H2H3 coupling constants can therefore be accurately measured in the acquisition dimension from the displacement of the E. COSY multiplet components, which are separated by the relatively large 1 J H3N3 coupling constants in the indirect dimension of the two-dimensional experiment. The 3h J H2H3 scalar coupling constants determined for AU base pairs in the two RNA hairpins examined here have been found to be positive and range in magnitude up to 1.8 Hz. Using a molecular fragment representation of an AU base pair, density functional theory/finite field perturbation theory (DFT/FPT) methods have been applied to attempt to predict the relative contributions of H-bond length and angular geometry to the magnitude of 3h J H2H3 coupling constants. Although the DFT/FPT calculations did not reproduce the full range of magnitude observed experimentally for the 3h J H2H3 coupling constants, the calculations do predict the correct sign and general trends in variation in size of these coupling constants. The calculations suggest that the magnitude of the coupling constants depends largely on H-bond length, but can also vary with differences in base pair geometry. The dependency of the 3h J H2H3 coupling constant on H-bond strength and geometry makes it a new probe for defining base pairs in NMR studies of nucleic acids

  9. Work-related exhaustion and telomere length: a population-based study.

    Directory of Open Access Journals (Sweden)

    Kirsi Ahola

    Full Text Available Psychological stress is suggested to accelerate the rate of biological aging. We investigated whether work-related exhaustion, an indicator of prolonged work stress, is associated with accelerated biological aging, as indicated by shorter leukocyte telomeres, that is, the DNA-protein complexes that cap chromosomal ends in cells.We used data from a representative sample of the Finnish working-age population, the Health 2000 Study. Our sample consisted of 2911 men and women aged 30-64. Work-related exhaustion was assessed using the Maslach Burnout Inventory--General Survey. We determined relative leukocyte telomere length using a quantitative real-time polymerase chain reaction (PCR -based method.After adjustment for age and sex, individuals with severe exhaustion had leukocyte telomeres on average 0.043 relative units shorter (standard error of the mean 0.016 than those with no exhaustion (p = 0.009. The association between exhaustion and relative telomere length remained significant after additional adjustment for marital and socioeconomic status, smoking, body mass index, and morbidities (adjusted difference 0.044 relative units, standard error of the mean 0.017, p = 0.008.These data suggest that work-related exhaustion is related to the acceleration of the rate of biological aging. This hypothesis awaits confirmation in a prospective study measuring changes in relative telomere length over time.

  10. Single-Camera-Based Method for Step Length Symmetry Measurement in Unconstrained Elderly Home Monitoring.

    Science.gov (United States)

    Cai, Xi; Han, Guang; Song, Xin; Wang, Jinkuan

    2017-11-01

    single-camera-based gait monitoring is unobtrusive, inexpensive, and easy-to-use to monitor daily gait of seniors in their homes. However, most studies require subjects to walk perpendicularly to camera's optical axis or along some specified routes, which limits its application in elderly home monitoring. To build unconstrained monitoring environments, we propose a method to measure step length symmetry ratio (a useful gait parameter representing gait symmetry without significant relationship with age) from unconstrained straight walking using a single camera, without strict restrictions on walking directions or routes. according to projective geometry theory, we first develop a calculation formula of step length ratio for the case of unconstrained straight-line walking. Then, to adapt to general cases, we propose to modify noncollinear footprints, and accordingly provide general procedure for step length ratio extraction from unconstrained straight walking. Our method achieves a mean absolute percentage error (MAPE) of 1.9547% for 15 subjects' normal and abnormal side-view gaits, and also obtains satisfactory MAPEs for non-side-view gaits (2.4026% for 45°-view gaits and 3.9721% for 30°-view gaits). The performance is much better than a well-established monocular gait measurement system suitable only for side-view gaits with a MAPE of 3.5538%. Independently of walking directions, our method can accurately estimate step length ratios from unconstrained straight walking. This demonstrates our method is applicable for elders' daily gait monitoring to provide valuable information for elderly health care, such as abnormal gait recognition, fall risk assessment, etc. single-camera-based gait monitoring is unobtrusive, inexpensive, and easy-to-use to monitor daily gait of seniors in their homes. However, most studies require subjects to walk perpendicularly to camera's optical axis or along some specified routes, which limits its application in elderly home monitoring

  11. The impact of length of stay on recovery measures in faith-based addiction treatment.

    Science.gov (United States)

    Lashley, Mary

    2018-03-30

    To determine the impact of length of stay among homeless men in faith-based residential addictions recovery on physical activity, depression, self-esteem, and nicotine dependence. A time series design was utilized to measure changes in the four quality measures at program entry and at 3, 6, and 9 months following admission. The sample consisted of 175 homeless residents enrolled in a faith-based residential recovery program. Paired t tests were used to determine the change in average instrument response from admission to each follow-up period. Analysis of variance (ANOVA) and Tukey posthoc tests were used to assess for differences in length of stay between demographic variables. Statistically significant improvements were noted in self-esteem and depressive symptomatology at 3 and 6 months following admission and in physical activity levels at 3 months following admission. Nicotine dependence scores declined at 3 and 6 months but were not statistically significant. Time spent in this faith-based spiritual recovery program had a significant impact on depression, self-esteem, and physical activity. Recommendations for future study include conducting research to analyze the relationship between distinct program elements and quality indicators and comparing faith-based programs to other similar programs and to publicly funded secular recovery programs. © 2018 Wiley Periodicals, Inc.

  12. Horizontal Directional Drilling-Length Detection Technology While Drilling Based on Bi-Electro-Magnetic Sensing

    Directory of Open Access Journals (Sweden)

    Yudan Wang

    2017-04-01

    Full Text Available The drilling length is an important parameter in the process of horizontal directional drilling (HDD exploration and recovery, but there has been a lack of accurate, automatically obtained statistics regarding this parameter. Herein, a technique for real-time HDD length detection and a management system based on the electromagnetic detection method with a microprocessor and two magnetoresistive sensors employing the software LabVIEW are proposed. The basic principle is to detect the change in the magnetic-field strength near a current coil while the drill stem and drill-stem joint successively pass through the current coil forward or backward. The detection system consists of a hardware subsystem and a software subsystem. The hardware subsystem employs a single-chip microprocessor as the main controller. A current coil is installed in front of the clamping unit, and two magneto resistive sensors are installed on the sides of the coil symmetrically and perpendicular to the direction of movement of the drill pipe. Their responses are used to judge whether the drill-stem joint is passing through the clamping unit; then, the order of their responses is used to judge the movement direction. The software subsystem is composed of a visual software running on the host computer and a software running in the slave microprocessor. The host-computer software processes, displays, and saves the drilling-length data, whereas the slave microprocessor software operates the hardware system. A combined test demonstrated the feasibility of the entire drilling-length detection system.

  13. Communication disruption of guava moth (Coscinoptycha improbana) using a pheromone analog based on chain length.

    Science.gov (United States)

    Suckling, D M; Dymock, J J; Park, K C; Wakelin, R H; Jamieson, L E

    2013-09-01

    The guava moth, Coscinoptycha improbana, an Australian species that infests fruit crops in commercial and home orchards, was first detected in New Zealand in 1997. A four-component pheromone blend was identified but is not yet commercially available. Using single sensillum recordings from male antennae, we established that the same olfactory receptor neurons responded to two guava moth sex pheromone components, (Z)-11-octadecen-8-one and (Z)-12-nonadecen-9-one, and to a chain length analog, (Z)-13-eicosen-10-one, the sex pheromone of the related peach fruit moth, Carposina sasakii. We then field tested whether this non-specificity of the olfactory neurons might enable disruption of sexual communication by the commercially available analog, using male catch to synthetic lures in traps in single-tree, nine-tree and 2-ha plots. A disruptive pheromone analog, based on chain length, is reported for the first time. Trap catches for guava moth were disrupted by three polyethylene tubing dispensers releasing the analog in single-tree plots (86% disruption of control catches) and in a plots of nine trees (99% disruption). Where peach fruit moth pheromone dispensers were deployed at a density of 1000/ha in two 2-ha areas, pheromone traps for guava moth were completely disrupted for an extended period (up to 470 days in peri-urban gardens in Mangonui and 422 days in macadamia nut orchards in Kerikeri). In contrast, traps in untreated areas over 100 m away caught 302.8 ± 128.1 moths/trap in Mangonui and 327.5 ± 78.5 moths/ trap in Kerikeri. The longer chain length in the pheromone analog has greater longevity than the natural pheromone due to its lower volatility. Chain length analogs may warrant further investigation for mating disruption in Lepidoptera, and screening using single-sensillum recording is recommended.

  14. Interfacial micromorphological differences in hybrid layer formation between water- and solvent-based dentin bonding systems.

    Science.gov (United States)

    Gregoire, Geneviève L; Akon, Bernadette A; Millas, Arlette

    2002-06-01

    Many dentin bonding systems of different compositions, and in particular containing different solvents, have been introduced to the market. Their effect on the quality of the interface requires clarification by means of comparative trials. This study investigated micromorphological differences in hybrid layer formation with a variety of commercially available water- or solvent-based dentin bonding products and their recommended compomers. Five bonding systems were used on groups of 10 teeth each as follows: group I, acetone-based system used with 36% phosphoric acid; group II, a different acetone-based system containing nano-sized particles for filler loading and used with a non-rinsing conditioner containing maleic acid; group III, the acetone-based system of group II used with 36% phosphoric acid (the only difference in the treatment for groups II and III was the acid etching system); group IV, a mixed-solvent-based system (water/ethanol) used with 37% phosphoric acid; and group V, a water-based system used with 37% phosphoric acid. Each bonding system was covered with the recommended compomer. Class I occlusal preparations were made in extracted teeth and restored with one of the above systems. Five specimens of each group were studied with optical microscopy after staining. Scanning electron microscopy was used to examine the interface of the bonding system/dentin of the other 5 teeth in each group. The optical microscopy measurements were made with a 10 x 10 reticle. A micron mark with scale was used for the scanning electron microscope. All measurements were made in microm. The following criteria were used to define a good interface: absence of voids between the different parts of the interface, uniformity of the hybrid layer, good opening of the tubuli orifices, and tag adherence to the tubuli walls. Morphological differences were found at the interface depending on dentin treatment and adhesive composition. The acetone-containing systems were associated

  15. PC-based arc ignition and arc length control system for gas tungsten arc welding

    International Nuclear Information System (INIS)

    Liu, Y.; Cook, G.E.; Barnett, R.J.; Springfield, J.F.

    1992-01-01

    In this paper, a PC-based digital control system for gas tungsten arc welding (GTAW) is presented. This system controls the arc ignition process, the arc length, and the process of welding termination. A DT2818 made by Data Translation is used for interface and A/D and D/A conversions. The digital I/O ports of the DT2818 are used for control of wirefeed, shield gas, cooling water, welding power supply, etc. The DT2818 is housed in a PC. The welding signals and status are displayed on the screen for in-process monitoring. A user can control the welding process by the keyboard

  16. An ancient relation between units of length and volume based on a sphere.

    Directory of Open Access Journals (Sweden)

    Elena Zapassky

    Full Text Available The modern metric system defines units of volume based on the cube. We propose that the ancient Egyptian system of measuring capacity employed a similar concept, but used the sphere instead. When considered in ancient Egyptian units, the volume of a sphere, whose circumference is one royal cubit, equals half a hekat. Using the measurements of large sets of ancient containers as a database, the article demonstrates that this formula was characteristic of Egyptian and Egyptian-related pottery vessels but not of the ceramics of Mesopotamia, which had a different system of measuring length and volume units.

  17. Optimum dose of 2-hydroxyethyl methacrylate based bonding material on pulp cells toxicity

    OpenAIRE

    Saraswati, Widya

    2010-01-01

    Background: 2-hydroxyethyl methacrylate (HEMA), one type of resins commonly used as bonding base material, is commonly used due to its advantageous chemical characteristics. Several preliminary studies indicated that resin is a material capable to induce damage in dentin-pulp complex. It is necessary to perform further investigation related with its biological safety for hard and soft tissues in oral cavity. Purpose: The author performed an in vitro test to find optimum dose of HEMA resin mon...

  18. Moisture diffusion coefficients determination of furan bonded sands and water based foundry coatings

    DEFF Research Database (Denmark)

    Di Muoio, Giovanni Luca; Tiedje, Niels Skat

    2016-01-01

    Moisture content in furan bonded sand and water based coatings can be one of the main causes for gas related defects in large cast iron parts. Moisture diffusion coefficients for these materials are needed to precisely predict the possible moisture levels in foundry moulds. In this study, we first...... provide an example on how it is possible to apply this knowledge to estimate moisture variation in a sand mould during production....

  19. Improving Erosion Resistance of Plasma-Sprayed Ceramic Coatings by Elevating the Deposition Temperature Based on the Critical Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2018-01-01

    Interlamellar bonding within plasma-sprayed coatings is one of the most important factors dominating the properties and performance of coatings. The interface bonding between lamellae significantly influences the erosion behavior of plasma-sprayed ceramic coatings. In this study, TiO2 and Al2O3 coatings with different microstructures were deposited at different deposition temperatures based on the critical bonding temperature concept. The erosion behavior of ceramic coatings was investigated. It was revealed that the coatings prepared at room temperature exhibit a typical lamellar structure with numerous unbonded interfaces, whereas the coatings deposited at the temperature above the critical bonding temperature present a dense structure with well-bonded interfaces. The erosion rate decreases sharply with the improvement of interlamellar bonding when the deposition temperature increases to the critical bonding temperature. In addition, the erosion mechanisms of ceramic coatings were examined. The unbonded interfaces in the conventional coatings act as pre-cracks accelerating the erosion of coatings. Thus, controlling interlamellar bonding formation based on the critical bonding temperature is an effective approach to improve the erosion resistance of plasma-sprayed ceramic coatings.

  20. Chemically-bonded brick production based on burned clay by means of semidry pressing

    Energy Technology Data Exchange (ETDEWEB)

    Voroshilov, Ivan, E-mail: Nixon.06@mail.ru; Endzhievskaya, Irina, E-mail: icaend@mail.ru; Vasilovskaya, Nina, E-mail: icaend@mail.ru [FSAEI HVE Siberian Federal University, 82 Svobodny Prospekt, Krasnoyarsk, 660130 (Russian Federation)

    2016-01-15

    We presented a study on the possibility of using the burnt rocks of the Krasnoyarsk Territory for production of chemically-bonded materials in the form of bricks which are so widely used in multistory housing and private house construction. The radiographic analysis of the composition of burnt rock was conducted and a modifier to adjust the composition uniformity was identified. The mixing moisture content was identified and optimal amount at 13-15% was determined. The method of semidry pressing has been chosen. The process of obtaining moldings has been theoretically proved; the advantages of chemically-bonded wall materials compared to ceramic brick were shown. The production of efficient artificial stone based on material burnt rocks, which is comparable with conventionally effective ceramic materials or effective with cell tile was proved, the density of the burned clay-based cell tile makes up to 1630-1785 kg \\ m{sup 3}, with compressive strength of 13.6-20.0 MPa depending on the compression ratio and cement consumption, frost resistance index is F50, and the thermal conductivity in the masonry is λ = 0,459-0,546 W \\ m {sup *} °C. The clear geometric dimensions of pressed products allow the use of the chemically-bonded brick based on burnt clay as a facing brick.

  1. Cleavage of thymine N3-H bonds by low-energy electrons attached to base π* orbitals

    International Nuclear Information System (INIS)

    Theodore, Magali; Sobczyk, Monika; Simons, Jack

    2006-01-01

    In this work, we extend our earlier studies on single strand break (SSB) formation in DNA to consider the possibility of cleaving a thymine N 3 -H bond to generate a nitrogen-centered anion and a hydrogen radical which might proceed to induce further bond cleavages. In earlier studies, we considered SSBs induced by low-energy electrons that attach to DNA bases' π* orbitals or to phosphate P=O π* orbitals to cleave sugar-phosphate C-O bonds or base-sugar N 1 -C bonds. We also studied the effects of base π-stacking on the rates of such bond cleavages. To date, our results suggest that sugar-phosphate C-O bonds have the lowest barriers to cleavage, that attachment of electrons with energies below 2 eV most likely occurs at the base π* orbitals, that electrons with energy above 2 eV can also attach to phosphate P=O π* orbitals, and that base π stacking has a modest but slowing effect on the rates of SSB formation. However, we had not yet examined the possibility that base N 3 -H bonds could rupture subsequent to base π* orbital capture. In the present work, the latter possibility is considered and it is found that the barrier to cleavage of the N 3 -H bond in thymine is considerably higher than for cleaving sugar-phosphate C-O bonds, so our prediction that SSB formation is dominated by C-O bond cleavage remains intact

  2. Shear Bond Strength of Ceramic Brackets with Different Base Designs: Comparative In-vitro Study

    Science.gov (United States)

    Ansari, Mohd. Younus; Agarwal, Deepak K; Bhattacharya, Preeti; Ansar, Juhi; Bhandari, Ravi

    2016-01-01

    Introduction Knowledge about the Shear Bond Strength (SBS) of ceramic brackets with different base design is essential as it affects bond strength to enamel. Aim The aim of the present study was to evaluate and compare the effect of base designs of different ceramic brackets on SBS, and to determine the fracture site after debonding. Materials and Methods Four groups of ceramic brackets and one group of metal brackets with different base designs were used. Adhesive precoated base of Clarity Advanced (APC Flash-free) (Unitek/3M, Monrovia, California), microcrystalline base of Clarity Advanced (Unitek/3M, Monrovia, California), polymer mesh base of InVu (TP Orthodontics, Inc., La Porte, IN, United States), patented bead ball base of Inspire Ice (Ormco, Glendora, California), and a mechanical mesh base of Gemini Metal bracket (Unitek/3M, Monrovia, California). Ten brackets of each type were bonded to 50 maxillary premolars with Transbond XT (Unitek/3M). Samples were stored in distilled water at room temperature for 24 hours and subsequently tested in shear mode on a universal testing machine (Model 3382; Instron Corp., Canton, Massachusetts, USA) at a cross head speed of 1mm/minute with the help of a chisel. The debonded interface was recorded and analyzed to determine the predominant bond failure site under an optical microscope (Stereomicroscope) at 10X magnification. One way analysis of variance (ANOVA) was used to compare SBS. Tukey’s significant differences tests were used for post-hoc comparisons. The Adhesive Remnant Index (ARI) scores were compared by chi-square test. Results Mean SBS of microcrystalline base (27.26±1.73), was the highest followed by bead ball base (23.45±5.09), adhesive precoated base (20.13±5.20), polymer mesh base (17.54±1.91), and mechanical mesh base (17.50±2.41) the least. Comparing the frequency (%) of ARI Score among the groups, chi-square test showed significantly different ARI scores among the groups (χ2 = 34.07, pbrackets

  3. Evaluation of genetic diversity in jackfruit (Artocarpus heterophyllus Lam.) based on amplified fragment length polymorphism markers.

    Science.gov (United States)

    Shyamalamma, S; Chandra, S B C; Hegde, M; Naryanswamy, P

    2008-07-22

    Artocarpus heterophyllus Lam., commonly called jackfruit, is a medium-sized evergreen tree that bears high yields of the largest known edible fruit. Yet, it has been little explored commercially due to wide variation in fruit quality. The genetic diversity and genetic relatedness of 50 jackfruit accessions were studied using amplified fragment length polymorphism markers. Of 16 primer pairs evaluated, eight were selected for screening of genotypes based on the number and quality of polymorphic fragments produced. These primer combinations produced 5976 bands, 1267 (22%) of which were polymorphic. Among the jackfruit accessions, the similarity coefficient ranged from 0.137 to 0.978; the accessions also shared a large number of monomorphic fragments (78%). Cluster analysis and principal component analysis grouped all jackfruit genotypes into three major clusters. Cluster I included the genotypes grown in a jackfruit region of Karnataka, called Tamaka, with very dry conditions; cluster II contained the genotypes collected from locations having medium to heavy rainfall in Karnataka; cluster III grouped the genotypes in distant locations with different environmental conditions. Strong coincidence of these amplified fragment length polymorphism-based groupings with geographical localities as well as morphological characters was observed. We found moderate genetic diversity in these jackfruit accessions. This information should be useful for tree breeding programs, as part of our effort to popularize jackfruit as a commercial crop.

  4. A QoS-Based Dynamic Queue Length Scheduling Algorithm in Multiantenna Heterogeneous Systems

    Directory of Open Access Journals (Sweden)

    Verikoukis Christos

    2010-01-01

    Full Text Available The use of real-time delay-sensitive applications in wireless systems has significantly grown during the last years. Therefore the designers of wireless systems have faced a challenging issue to guarantee the required Quality of Service (QoS. On the other hand, the recent advances and the extensive use of multiple antennas have already been included in several commercial standards, where the multibeam opportunistic transmission beamforming strategies have been proposed to improve the performance of the wireless systems. A cross-layer-based dynamically tuned queue length scheduler is presented in this paper, for the Downlink of multiuser and multiantenna WLAN systems with heterogeneous traffic requirements. To align with modern wireless systems transmission strategies, an opportunistic scheduling algorithm is employed, while a priority to the different traffic classes is applied. A tradeoff between the maximization of the throughput of the system and the guarantee of the maximum allowed delay is obtained. Therefore, the length of the queue is dynamically adjusted to select the appropriate conditions based on the operator requirements.

  5. [Biological and neural bases of partner preferences in rodents: models to understand human pair bonds].

    Science.gov (United States)

    Coria-Avila, G A; Hernández-Aguilar, M E; Toledo-Cárdenas, R; García-Hernández, L I; Manzo, J; Pacheco, P; Miquel, M; Pfaus, J G

    To analyse the biological and neural bases of partner preference formation in rodents as models to understand human pair bonding. Rodents are social individuals, capable of forming short- or long-lasting partner preferences that develop slowly by stimuli like cohabitation, or rapidly by stimuli like sex and stress. Dopamine, corticosteroids, oxytocin, vasopressin, and opioids form the neurochemical substrate for pair bonding in areas like the nucleus accumbens, the prefrontal cortex, the piriform cortex, the medial preoptic area, the ventral tegmental area and the medial amygdala, among others. Additional areas may participate depending on the nature of the conditioned stimuli by which and individual recognizes a preferred partner. Animal models help us understand that the capacity of an individual to display long-lasting and selective preferences depends on neural bases, selected throughout evolution. The challenge in neuroscience is to use this knowledge to create new solutions for mental problems associated with the incapacity of an individual to display a social bond, keep one, or cope with the disruption of a consolidated one.

  6. Comparison of shear bond strength of four types of orthodontic brackets with different base technologies

    Directory of Open Access Journals (Sweden)

    Gaurang H Chaudhary

    2017-01-01

    Full Text Available Objectives: The aim of this study was to compare the shear bond strength (SBS of brackets systems with four different base technologies. Materials and Methods: Maxillary first premolars were randomly divided into four groups of thirty specimens each: (1 Master Series™ conventional twin, (2 T3™ self-ligating, (3 Victory series™ conventional twin, and (4 H4™ self-ligating brackets. Maxillary first premolars were bracketed using an acid-etch composite system, and the SBS measured using an Instron Universal Testing Machine at a crosshead speed of 2 mm/min. The ANOVA and Tukey's multiple comparison tests were performed with significance predetermined at P ≤ 0.05. Results: The overall mean bond strengths were 8.49 ± 2.93, 10.85 ± 3.34, 9.42 ± 2.97, and 9.73 ± 2.62 for the Groups 1, 2, 3, and 4 brackets, respectively. One-way ANOVA test gave an F = 3.182 with a P = 0.026. The Group 1 and Group 2 were observed to have statistically significant difference with a P = 0.014. Conclusions: The T3 self-ligating one-piece design with microetched Quadra Grip™ base brackets had the highest bond strength. The SBS difference between Group 2, Group 3, and Group 4 was not significant, but the difference between Group 2 and Group 1 was statistically significant.

  7. A Microsystem Based on Porous Silicon-Glass Anodic Bonding for Gas and Liquid Optical Sensing

    Directory of Open Access Journals (Sweden)

    Ivo Rendina

    2006-06-01

    Full Text Available We have recently presented an integrated silicon-glass opto-chemical sensor forlab-on-chip applications, based on porous silicon and anodic bonding technologies. In thiswork, we have optically characterized the sensor response on exposure to vapors of severalorganic compounds by means of reflectivity measurements. The interaction between theporous silicon, which acts as transducer layer, and the organic vapors fluxed into the glasssealed microchamber, is preserved by the fabrication process, resulting in optical pathincrease, due to the capillary condensation of the vapors into the pores. Using theBruggemann theory, we have calculated the filled pores volume for each substance. Thesensor dynamic has been described by time-resolved measurements: due to the analysischamber miniaturization, the response time is only of 2 s. All these results have beencompared with data acquired on the same PSi structure before the anodic bonding process.

  8. Mission-profile-based stress analysis of bond-wires in SiC power modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Blaabjerg, Frede

    2016-01-01

    This paper proposes a novel mission-profile-based reliability analysis approach for stress on bond wires in Silicon Carbide (SiC) MOSFET power modules using statistics and thermo-mechanical FEM analysis. In the proposed approach, both the operational and environmental thermal stresses are taken...... into account. The approach uses a two-dimension statistical analysis of the operating conditions in a real one-year mission profile sampled at time frames 5 minutes long. For every statistical bin corresponding to a given operating condition, the junction temperature evolution is estimated by a thermal network...... and the mechanical stress on bond wires is consequently extracted by finite-element simulations. In the final step, the considered mission profile is translated in a stress sequence to be used for Rainflow counting calculation and lifetime estimation....

  9. Infant bone age estimation based on fibular shaft length: model development and clinical validation

    International Nuclear Information System (INIS)

    Tsai, Andy; Stamoulis, Catherine; Bixby, Sarah D.; Breen, Micheal A.; Connolly, Susan A.; Kleinman, Paul K.

    2016-01-01

    Bone age in infants (<1 year old) is generally estimated using hand/wrist or knee radiographs, or by counting ossification centers. The accuracy and reproducibility of these techniques are largely unknown. To develop and validate an infant bone age estimation technique using fibular shaft length and compare it to conventional methods. We retrospectively reviewed negative skeletal surveys of 247 term-born low-risk-of-abuse infants (no persistent child protection team concerns) from July 2005 to February 2013, and randomized them into two datasets: (1) model development (n = 123) and (2) model testing (n = 124). Three pediatric radiologists measured all fibular shaft lengths. An ordinary linear regression model was fitted to dataset 1, and the model was evaluated using dataset 2. Readers also estimated infant bone ages in dataset 2 using (1) the hemiskeleton method of Sontag, (2) the hemiskeleton method of Elgenmark, (3) the hand/wrist atlas of Greulich and Pyle, and (4) the knee atlas of Pyle and Hoerr. For validation, we selected lower-extremity radiographs of 114 normal infants with no suspicion of abuse. Readers measured the fibulas and also estimated bone ages using the knee atlas. Bone age estimates from the proposed method were compared to the other methods. The proposed method outperformed all other methods in accuracy and reproducibility. Its accuracy was similar for the testing and validating datasets, with root-mean-square error of 36 days and 37 days; mean absolute error of 28 days and 31 days; and error variability of 22 days and 20 days, respectively. This study provides strong support for an infant bone age estimation technique based on fibular shaft length as a more accurate alternative to conventional methods. (orig.)

  10. Infant bone age estimation based on fibular shaft length: model development and clinical validation

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Andy; Stamoulis, Catherine; Bixby, Sarah D.; Breen, Micheal A.; Connolly, Susan A.; Kleinman, Paul K. [Boston Children' s Hospital, Harvard Medical School, Department of Radiology, Boston, MA (United States)

    2016-03-15

    Bone age in infants (<1 year old) is generally estimated using hand/wrist or knee radiographs, or by counting ossification centers. The accuracy and reproducibility of these techniques are largely unknown. To develop and validate an infant bone age estimation technique using fibular shaft length and compare it to conventional methods. We retrospectively reviewed negative skeletal surveys of 247 term-born low-risk-of-abuse infants (no persistent child protection team concerns) from July 2005 to February 2013, and randomized them into two datasets: (1) model development (n = 123) and (2) model testing (n = 124). Three pediatric radiologists measured all fibular shaft lengths. An ordinary linear regression model was fitted to dataset 1, and the model was evaluated using dataset 2. Readers also estimated infant bone ages in dataset 2 using (1) the hemiskeleton method of Sontag, (2) the hemiskeleton method of Elgenmark, (3) the hand/wrist atlas of Greulich and Pyle, and (4) the knee atlas of Pyle and Hoerr. For validation, we selected lower-extremity radiographs of 114 normal infants with no suspicion of abuse. Readers measured the fibulas and also estimated bone ages using the knee atlas. Bone age estimates from the proposed method were compared to the other methods. The proposed method outperformed all other methods in accuracy and reproducibility. Its accuracy was similar for the testing and validating datasets, with root-mean-square error of 36 days and 37 days; mean absolute error of 28 days and 31 days; and error variability of 22 days and 20 days, respectively. This study provides strong support for an infant bone age estimation technique based on fibular shaft length as a more accurate alternative to conventional methods. (orig.)

  11. 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...

  12. Quantification of wall motion and phase of contraction in tomographic gated blood pool studies using length-based Fourier analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Kenichi; Bunko, Hisashi; Taki, Junichi; Nambu, Ichiro; Shiire, Yasushi; Tonami, Norihisa; Hisada, Kinichi; Tada, Akira; Kojima, Kazuhkio

    1985-03-01

    Length-based Fourier analysis, a new method for quantification of wall motion and timing of contraction, was applied to tomographic gated blood pool study. Two parameters, percent-length shortening (%LS) and length-based phase were calculated based on the time-length curves from a center to ventricular edges, and compared with the count-based method. In mathematical models for tomographic gated blood pool images, the severity of asynergy was easily determined by length-based method, and the accuracy of the parameters was good. As to the setting of the center, fixed center provided more reliable parameters than the method using movable center, i.e., when a center of gravity was determined in each frame. By length-based Fourier analysis, quantification of wall motion was easily performed, and the initial inward movement caused by the accessory conduction pathway was assessed in patients with Wolff-Parkinson-White syndrome. Length-based approach was considered to be reasonable and effective because the movements of the ventricular edges are essential in tomographic gated blood pool images.

  13. Quantification of wall motion and phase of contraction in tomographic gated blood pool studies using length-based Fourier analysis

    International Nuclear Information System (INIS)

    Nakajima, Kenichi; Bunko, Hisashi; Taki, Junichi; Nambu, Ichiro; Shiire, Yasushi; Tonami, Norihisa; Hisada, Kinichi; Tada, Akira; Kojima, Kazuhiko.

    1985-01-01

    Length-based Fourier analysis, a new method for quantification of wall motion and timing of contraction, was applied to tomographic gated blood pool study. Two parameters, percent-length shortening (%LS) and length-based phase were calculated based on the time-length curves from a center to ventricular edges, and compared with the count-based method. In mathematical models for tomographic gated blood pool images, the severity of asynergy was easily determined by length-based method, and the accuracy of the parameters was good. As to the setting of the center, fixed center provided more reliable parameters than the method using movable center, i.e., when a center of gravity was determined in each frame. By length-based Fourier analysis, quantification of wall motion was easily performed, and the initial inward movement caused by the accessory conduction pathway was assessed in patients with Wolff-Parkinson-White syndrome. Length-based approach was considered to be reasonable and effective because the movements of the ventricular edges are essential in tomographic gated blood pool images. (author)

  14. An Erbium-Based Bifuctional Heterogeneous Catalyst: A Cooperative Route Towards C-C Bond Formation

    Directory of Open Access Journals (Sweden)

    Manuela Oliverio

    2014-07-01

    Full Text Available Heterogeneous bifuctional catalysts are multifunctional synthetic catalysts enabling efficient organic transformations by exploiting two opposite functionalities without mutual destruction. In this paper we report the first Er(III-based metallorganic heterogeneous catalyst, synthesized by post-calcination MW-assisted grafting and modification of the natural aminoacid L-cysteine. The natural acid–base distance between sites was maintained to assure the cooperation. The applicability of this new bifunctional heterogeneous catalyst to C-C bond formation and the supposed mechanisms of action are discussed as well.

  15. Marginal microleakage of class V resin-based composite restorations bonded with six one-step self-etch systems

    Directory of Open Access Journals (Sweden)

    Alfonso Sánchez-Ayala

    2013-06-01

    Full Text Available This study compared the microleakage of class V restorations bonded with various one-step self-etching adhesives. Seventy class V resin-based composite restorations were prepared on the buccal and lingual surfaces of 35 premolars, by using: Clearfil S 3 Bond, G-Bond, iBond, One Coat 7.0, OptiBond All-In-One, or Xeno IV. The Adper Single Bond etch-and-rinse two-step adhesive was employed as a control. Specimens were thermocycled for 500 cycles in separate water baths at 5°C and 55°C and loaded under 40 to 70 N for 50,000 cycles. Marginal microleakage was measured based on the penetration of a tracer agent. Although the control showed no microleakage at the enamel margins, there were no differences between groups (p = 0.06. None of the adhesives avoided microleakage at the dentin margins, and they displayed similar performances (p = 0.76. When both margins were compared, iBond® presented higher microleakage (p < 0.05 at the enamel margins (median, 1.00; Q3–Q1, 1.25–0.00 compared to the dentin margins (median, 0.00; Q3–Q1, 0.25–0.00. The study adhesives showed similar abilities to seal the margins of class V restorations, except for iBond®, which presented lower performance at the enamel margin.

  16. Hydrogels Based on Dynamic Covalent and Non Covalent Bonds: A Chemistry Perspective

    Directory of Open Access Journals (Sweden)

    Francesco Picchioni

    2018-03-01

    Full Text Available Hydrogels based on reversible covalent bonds represent an attractive topic for research at both academic and industrial level. While the concept of reversible covalent bonds dates back a few decades, novel developments continue to appear in the general research area of gels and especially hydrogels. The reversible character of the bonds, when translated at the general level of the polymeric network, allows reversible interaction with substrates as well as responsiveness to variety of external stimuli (e.g., self-healing. These represent crucial characteristics in applications such as drug delivery and, more generally, in the biomedical world. Furthermore, the several possible choices that can be made in terms of reversible interactions generate an almost endless number of possibilities in terms of final product structure and properties. In the present work, we aim at reviewing the latest developments in this field (i.e., the last five years by focusing on the chemistry of the systems at hand. As such, this should allow molecular designers to develop a toolbox for the synthesis of new systems with tailored properties for a given application.

  17. Using Agent-Based Modeling to Assess Liquidity Mismatch in Open-End Bond Funds

    Directory of Open Access Journals (Sweden)

    Donald J. Berndt

    2017-12-01

    Full Text Available In this paper, we introduce a small-scale heterogeneous agent-based model of the US corporate bond market. The model includes a realistic micro-grounded ecology of investors that trade a set of bonds through dealers. Using the model, we simulate market dynamics that emerge from agent behaviors in response to basic exogenous factors (such as interest rate shocks and the introduction of regulatory policies and constraints. A first experiment focuses on the liquidity transformation provided by mutual funds and investigates the conditions under which redemption-driven bond sales may trigger market instability. We simulate the effects of increasing mutual fund market shares in the presence of market-wide repricing of risk (in the form of a 100 basis point increase in the expected returns. The simulations highlight robust-yet-fragile aspects of the growing liquidity transformation provided by mutual funds, with an inflection point beyond which redemption-driven negative feedback loops trigger market instability.

  18. Boron-Based Catalysts for C-C Bond-Formation Reactions.

    Science.gov (United States)

    Rao, Bin; Kinjo, Rei

    2018-05-02

    Because the construction of the C-C bond is one of the most significant reactions in organic chemistry, the development of an efficient strategy has attracted much attention throughout the synthetic community. Among various protocols to form C-C bonds, organoboron compounds are not just limited to stoichiometric reagents, but have also made great achievements as catalysts because of the easy modification of the electronic and steric impacts on the boron center. This review presents recent developments of boron-based catalysts applied in the field of C-C bond-formation reactions, which are classified into four kinds on the basis of the type of boron catalyst: 1) highly Lewis acidic borane, B(C 6 F 5 ) 3 ; 2) organoboron acids, RB(OH) 2 , and their ester derivatives; 3) borenium ions, (R 2 BL)X; and 4) other miscellaneous kinds. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. 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.

  20. A chiroptical switch based on supramolecular chirality transfer through alkyl chain entanglement and dynamic covalent bonding.

    Science.gov (United States)

    Lv, Kai; Qin, Long; Wang, Xiufeng; Zhang, Li; Liu, Minghua

    2013-12-14

    Chirality transfer is an interesting phenomenon in Nature, which represents an important step to understand the evolution of chiral bias and the amplification of the chirality. In this paper, we report the chirality transfer via the entanglement of the alkyl chains between chiral gelator molecules and achiral amphiphilic Schiff base. We have found that although an achiral Schiff base amphiphile could not form organogels in any kind of organic solvents, it formed co-organogels when mixed with a chiral gelator molecule. Interestingly, the chirality of the gelator molecules was transferred to the Schiff base chromophore in the mixed co-gels and there was a maximum mixing ratio for the chirality transfer. Furthermore, the supramolecular chirality was also produced based on a dynamic covalent chemistry of an imine formed by the reaction between an aldehyde and an amine. Such a covalent bond of imine was formed reversibly depending on the pH variation. When the covalent bond was formed the chirality transfer occurred, when it was destroyed, the transfer stopped. Thus, a supramolecular chiroptical switch is obtained based on supramolecular chirality transfer and dynamic covalent chemistry.

  1. Evaluation of pipeline defect's characteristic axial length via model-based parameter estimation in ultrasonic guided wave-based inspection

    International Nuclear Information System (INIS)

    Wang, Xiaojuan; Tse, Peter W; Dordjevich, Alexandar

    2011-01-01

    The reflection signal from a defect in the process of guided wave-based pipeline inspection usually includes sufficient information to detect and define the defect. In previous research, it has been found that the reflection of guided waves from even a complex defect primarily results from the interference between reflection components generated at the front and the back edges of the defect. The respective contribution of different parameters of a defect to the overall reflection can be affected by the features of the two primary reflection components. The identification of these components embedded in the reflection signal is therefore useful in characterizing the concerned defect. In this research, we propose a method of model-based parameter estimation with the aid of the Hilbert–Huang transform technique for the purpose of decomposition of a reflection signal to enable characterization of the pipeline defect. Once two primary edge reflection components are decomposed and identified, the distance between the reflection positions, which closely relates to the axial length of the defect, could be easily and accurately determined. Considering the irregular profiles of complex pipeline defects at their two edges, which is often the case in real situations, the average of varied axial lengths of such a defect along the circumference of the pipeline is used in this paper as the characteristic value of actual axial length for comparison purpose. The experimental results of artificial defects and real corrosion in sample pipes were considered in this paper to demonstrate the effectiveness of the proposed method

  2. Race-based differences in length of stay among patients undergoing pancreatoduodenectomy.

    Science.gov (United States)

    Schneider, Eric B; Calkins, Keri L; Weiss, Matthew J; Herman, Joseph M; Wolfgang, Christopher L; Makary, Martin A; Ahuja, Nita; Haider, Adil H; Pawlik, Timothy M

    2014-09-01

    Race-based disparities in operative morbidity and mortality have been demonstrated for various procedures, including pancreatoduodenectomy (PD). Race-based differences in hospital length-of-stay (LOS), especially related to provider volume at the surgeon and hospital level, remain poorly defined. Using the 2003-2009 Nationwide Inpatient Sample, we determined year-specific PD volumes for surgeons and hospitals and grouped them into terciles. Patient race (white, black, or Hispanic), age, sex, and comorbidities were examined. Median length of stay was calculated, and multivariable logistic regression was used to examine factors associated with increased LOS. Among 4,319 eligible individuals, 3,502 (81.1%) were white, 423 (9.8%) were black, and 394 (9.1%) were Hispanic. Overall median LOS was 12 days (range, 0-234). Median annual surgeon volume was 8 (interquartile range [IQR], 2-19; range, 1-54). Annual hospital volume ranged from 1 to 129 (median, 19; IQR, 7-55). White patients were more likely to have been treated at medium- to high-volume hospitals (odds ratio [OR] 1.53, P < .001) and by medium- to high-volume surgeons (OR 1.62, P < .001) than black or Hispanic patients. After PD, white, black, and Hispanic patients demonstrated similar in-hospital mortality (5.1%, 5.7% and 7.2% respectively P = .250). After adjustment, black (OR 1.36, P = .010) and Hispanic (OR 1.68, P < .001) patients were more likely to have a greater LOS after PD. Black and Hispanic PD patients were less likely than white patients to be treated at higher-volume hospitals and by higher-volume surgeons. Proportional mortality and LOS after PD were greater among black and Hispanic patients. Copyright © 2014 Mosby, Inc. All rights reserved.

  3. The influence of size and structure of metal orthodontic bracket base on bond strength on tooth enamel

    Directory of Open Access Journals (Sweden)

    Mitić Vladimir

    2009-01-01

    Full Text Available Introduction. The factors which may influence the bond strength of the applied orthodontic brackets on the tooth surface are the size and structure of the bracket base. Objective. The aim of the paper was to investigate the influence of size and shape of different types of brackets on bond strength on the enamel and analyze the remaining quality of adhesive material on the tooth surface after debonding of orthodontic brackets (adhesive remnant index - ARI. Methods. In this study, three types of metal brackets of different sizes and shapes of Dentaurum manufacturer were used (Utratrimm, Equilibrium 2, Discovery, Dentaurum, Inspringen, Germany. The brackets were applied onto the middle part of the anatomic crowns of buccal surfaces of 30 premolars extracted for orthodontic reasons. In addition, the pre-treatment of teeth by 37% orthophosphoric acid and adhesive material System1+ (Dentaurum, Germany were used. Results. The mean value of the bonded brackets bond strength of Discovery type after debonding was 8.67±0.32 MPa, while the value of the bonded brackets bond strength of Equilibrium 2 type amounted to 8.62±0.22 MPa. The value of the bonded brackets bond strength of Ultratrimm type after debonding was 8.22±0.49 MPa. There were no statistical differences in the values of bond strength regarding all three groups of the investigated orthodontic brackets (F=4.56; p<0.05. Conclusion. The base size and design of metal orthodontic brackets did not play a significant role in bond strength, while the values of ARI index were identical in all three investigated groups.

  4. Biomaterial based novel polyurethane adhesives for wood to wood and metal to metal bonding

    Directory of Open Access Journals (Sweden)

    Mitesh Ramanlal Patel

    2009-01-01

    Full Text Available Polyurethane adhesives made from synthetic chemicals are non-biodegradable, costly and difficult to find raw materials from local market. To avoid solid pollution problem, cost effectiveness and easy availability of raw materials, biomaterials based polyurethane adhesives are used in current industrial interest. Direct use of castor oil in polyurethane adhesive gives limited hardness. Modification on active sites of castor oil to utilize double bond of unsaturated fatty acid and carboxyl group yields new modified or activated polyols, which can be utilized for polyurethane adhesive formulation. In view of this, we have synthesized polyurethane adhesives from polyester polyols, castor oil based polyols and epoxy based polyols with Isocyanate adducts based on castor oil and trimethylolpropane. To study the effects of polyurethane adhesive strength (i.e. lap shear strength on wood-to-wood and metal-to-metal bonding through various types of polyols, cross-linking density, isocyanate adducts and also to compare adhesive strength between wood to wood and metal to metal surface. These polyols and polyurethanes were characterized through GPC, NMR and IR-spectroscopy, gel and surface drying time. Thermal stability of PU adhesives was determined under the effect of cross-linking density (NCO/OH ratio. The NCO/OH ratio (1.5 was optimized for adhesives as the higher NCO/OH ratio (2.0 increasing cross-linking density and decreases adhesion. Lower NCO/OH ratio (1.0 provideslow cross-linking density and low strength of adhesives.

  5. Umbilical cord length in singleton gestations: a Finnish population-based retrospective register study.

    Science.gov (United States)

    Georgiadis, L; Keski-Nisula, L; Harju, M; Räisänen, S; Georgiadis, S; Hannila, M-L; Heinonen, S

    2014-04-01

    Many complications of pregnancy and delivery are associated with umbilical cord length. It is important to examine the variation in length, in order to identify normal and abnormal conditions. Moreover, the factors influencing cord growth and development are not precisely known. The main objectives were to provide updated reference charts for umbilical cord length in singleton pregnancies and to evaluate potential factors affecting cord length. Birth register data of 47,284 singleton pregnant women delivering in Kuopio University Hospital, Finland was collected prospectively. Gender-specific centile charts for cord length from 22 to 44 gestational weeks were obtained using generalized additive models for location, scale, and shape (GAMLSS). Gestational, fetal, and maternal factors were studied for their potential influence on cord length with single variable analysis and stepwise multiple linear regression analysis. Cord length increased according to gestational age, while the growth decelerated post-term. Birth weight, placental weight, pregravid maternal body mass index, parity, and maternal age correlated to cord length. Gestational diabetes and previous miscarriages were associated with longer cords, while female gender and placental abruption were associated with shorter cords. Girls had shorter cords throughout gestation although there was substantial variation in length in both genders. Cord length associated significantly with birth weight, placental weight, and gestational age. Significantly shorter cords were found in women with placental abruption. This important finding requires further investigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Estimation of Hydrogen-Exchange Protection Factors from MD Simulation Based on Amide Hydrogen Bonding Analysis

    Science.gov (United States)

    Park, In-Hee; Venable, John D.; Steckler, Caitlin; Cellitti, Susan E.; Lesley, Scott A.; Spraggon, Glen; Brock, Ansgar

    2015-01-01

    Hydrogen exchange (HX) studies have provided critical insight into our understanding of protein folding, structure and dynamics. More recently, Hydrogen Exchange Mass Spectrometry (HX-MS) has become a widely applicable tool for HX studies. The interpretation of the wealth of data generated by HX-MS experiments as well as other HX methods would greatly benefit from the availability of exchange predictions derived from structures or models for comparison with experiment. Most reported computational HX modeling studies have employed solvent-accessible-surface-area based metrics in attempts to interpret HX data on the basis of structures or models. In this study, a computational HX-MS prediction method based on classification of the amide hydrogen bonding modes mimicking the local unfolding model is demonstrated. Analysis of the NH bonding configurations from Molecular Dynamics (MD) simulation snapshots is used to determine partitioning over bonded and non-bonded NH states and is directly mapped into a protection factor (PF) using a logistics growth function. Predicted PFs are then used for calculating deuteration values of peptides and compared with experimental data. Hydrogen exchange MS data for Fatty acid synthase thioesterase (FAS-TE) collected for a range of pHs and temperatures was used for detailed evaluation of the approach. High correlation between prediction and experiment for observable fragment peptides is observed in the FAS-TE and additional benchmarking systems that included various apo/holo proteins for which literature data were available. In addition, it is shown that HX modeling can improve experimental resolution through decomposition of in-exchange curves into rate classes, which correlate with prediction from MD. Successful rate class decompositions provide further evidence that the presented approach captures the underlying physical processes correctly at the single residue level. This assessment is further strengthened in a comparison of

  7. Periprosthetic hip fractures: A review of the economic burden based on length of stay.

    Science.gov (United States)

    Lyons, Rebecca F; Piggott, Robert P; Curtin, William; Murphy, Colin G

    2018-03-01

    With the increasing rates of total hip replacements being performed worldwide, there is an increasing incidence of periprosthetic fractures. As our patients' demographics change to include older patients with multiple medical co-morbidities, there is a concurrent increase in morbidity and mortality rates. This leads to longer hospital stays and increasing hospital costs. In the current economic climate, the cost of treating periprosthetic fractures must be addressed and appropriate resource and funding allocation for future provision of services should be planned. All periprosthetic hip fractures that were admitted to a single trauma unit over a three-year period were reviewed. Independent chart review, haematological and radiological review was undertaken. All patients with a periprosthetic fracture associated with a total hip arthroplasty or hemiarthroplasty were included. Follow up data including complications were collated. Data from the hospital inpatient database and finance department was utilized for cost analysis. All statistical analysis was preformed using Minitab version 17. 48 patients were identified who met the inclusion criteria for review. The majority of participants were female with a mean age of 73.5 years. The mean time to fracture was 4.5 years (9 months-18.5 years). Periprosthetic fracture was associated with total hip arthroplasty in 24 cases and a Vancouver B2 classification was most common at n = 20. The majority of patients had revision arthroplasty, with a mean length of stay of 24 days for the whole cohort (9-42). Vancouver B3 fractures had the longest inpatient stay at a mean of 26 days. The mean cost of for a full revision of stem with additional plate and cable fixation was over €27000 compared to €14,600 for ORIF and cable fixation based on length of hospital stay. The prolonged length of stay associated with Vancouver B2 and B3 fractures leads to increased costs to the healthcare service. Accurately calculating

  8. Flexibility of short DNA helices with finite-length effect: From base pairs to tens of base pairs

    International Nuclear Information System (INIS)

    Wu, Yuan-Yan; Bao, Lei; Zhang, Xi; Tan, Zhi-Jie

    2015-01-01

    Flexibility of short DNA helices is important for the biological functions such as nucleosome formation and DNA-protein recognition. Recent experiments suggest that short DNAs of tens of base pairs (bps) may have apparently higher flexibility than those of kilo bps, while there is still the debate on such high flexibility. In the present work, we have studied the flexibility of short DNAs with finite-length of 5–50 bps by the all-atomistic molecular dynamics simulations and Monte Carlo simulations with the worm-like chain model. Our microscopic analyses reveal that short DNAs have apparently high flexibility which is attributed to the significantly strong bending and stretching flexibilities of ∼6 bps at each helix end. Correspondingly, the apparent persistence length l p of short DNAs increases gradually from ∼29 nm to ∼45 nm as DNA length increases from 10 to 50 bps, in accordance with the available experimental data. Our further analyses show that the short DNAs with excluding ∼6 bps at each helix end have the similar flexibility with those of kilo bps and can be described by the worm-like chain model with l p ∼ 50 nm

  9. A Fracture-Based Criterion for Debonding Strength of Adhesive-Bonded Double-Strap Steel Joints

    Directory of Open Access Journals (Sweden)

    Prawit Santisukpotha

    2012-01-01

    Full Text Available This paper addresses the debonding strength of adhesive-bonded double-strap steel joints. A fracture-based criterion was formulated in terms of a stress singularity parameter, i.e., the stress intensity factor, which governs the magnitude of a singular stress field near the joint ends. No existing crack was assumed. A total of 24 steel joint specimens were tested under constant amplitude fatigue loadings at stress ratio of 0.2 and frequency of 2 Hz. The joint stiffness ratio was slightly less than one to control the maximum adhesive stresses at the joint ends. To detect the debonding, a simple and practical technique was developed. The test results showed that the interfacial failure near the steel/adhesive corner was a dominant failure mode. The failure was brittle and the debonding life was governed by the crack initiation stage. The finite element analysis was employed to calculate the stress intensity factors and investigate the effects of the adhesive layer thickness, lap length and joint stiffness ratio on the debonding strength.

  10. Office-Based Tools and Primary Care Visit Communication, Length, and Preventive Service Delivery.

    Science.gov (United States)

    Lafata, Jennifer Elston; Shay, L Aubree; Brown, Richard; Street, Richard L

    2016-04-01

    The use of physician office-based tools such as electronic health records (EHRs), health risk appraisal (HRA) instruments, and written patient reminder lists is encouraged to support efficient, high-quality, patient-centered care. We evaluate the association of exam room use of EHRs, HRA instruments, and self-generated written patient reminder lists with patient-physician communication behaviors, recommended preventive health service delivery, and visit length. Observational study of 485 office visits with 64 primary care physicians practicing in a health system serving the Detroit metropolitan area. Study data were obtained from patient surveys, direct observation, office visit audio-recordings, and automated health system records. Outcome measures included visit length in minutes, patient use of active communication behaviors, physician use of supportive talk and partnership-building communication behaviors, and percentage of delivered guideline-recommended preventive health services for which patients are eligible and due. Simultaneous linear regression models were used to evaluate associations between tool use and outcomes. Adjusted models controlled for patient characteristics, physician characteristics, characteristics of the relationship between the patient and physician, and characteristics of the environment in which the visit took place. Prior to adjusting for other factors, visits in which the EHR was used on average were significantly (p communication behaviors facilitating patient involvement (2.1 vs. 2.6 occurrences), but more use of active patient communication behaviors (4.4 vs. 2.6). Likewise, HRA use was significantly associated with increased preventive services delivery (62.1 percent vs. 57.0 percent). All relationships remained significant (p > .05) in adjusted models with the exception of that between HRA use and preventive service delivery. Office-based tools intended to facilitate the implementation of desired primary care practice

  11. Middle finger length-based tracheal intubation depth improves the rate of appropriate tube placement in children.

    Science.gov (United States)

    Zhou, Qing-he; Xiao, Wang-pin; Zhou, Hong-mei

    2015-11-01

    It is challenging for anesthetists to determine the optimal tracheal intubation depth in children. We hypothesize that a measure three times the length of the middle finger can be used for predicting tracheal tube depth in children. Eighty-six children (4-14 years of age) were included in this study. After the children were anesthetized, a fiberoptic bronchoscope (FOB) was inserted into the trachea, the lengths from the upper incisor teeth to carina and vocal cords were measured, and a suitably sized cuffed tracheal tube was inserted into the trachea. Age-based and middle finger length-based formulas were used to determine the tracheal intubation depth. All 86 children enrolled were included in this study. Compared with the age-based intubation, the rate of appropriate tube placement was higher for middle finger length-based intubation (88.37% vs 66.28%, P = 0.001). The proximal intubation rate was lower in middle finger length-based intubation (4.65% vs 32.56%, P tube depth was larger than that between age and optimal tracheal tube depth (0.883 vs 0.845). Our data indicate that the appropriate tube placement rate can be improved by using three times the middle finger length as the tracheal intubation depth in children. © 2015 John Wiley & Sons Ltd.

  12. THE NETWORK OF CITY PUBLIC TRANSPORT AS THE BASE FOR TRIP LENGTH DISTRIBUTION DETERMINING

    Directory of Open Access Journals (Sweden)

    P. Horbachov

    2015-07-01

    Full Text Available The up-to-date methods of modelling the demand for public transport services require an objective estimation and improvement. Such an improvement can be achieved by taking into account the trip length distribution during trip matrix calculation that requires determining the reasons of regularities occurance in city population trip lengths.

  13. Microwave-assisted acid and base hydrolysis of intact proteins containing disulfide bonds for protein sequence analysis by mass spectrometry.

    Science.gov (United States)

    Reiz, Bela; Li, Liang

    2010-09-01

    Controlled hydrolysis of proteins to generate peptide ladders combined with mass spectrometric analysis of the resultant peptides can be used for protein sequencing. In this paper, two methods of improving the microwave-assisted protein hydrolysis process are described to enable rapid sequencing of proteins containing disulfide bonds and increase sequence coverage, respectively. It was demonstrated that proteins containing disulfide bonds could be sequenced by MS analysis by first performing hydrolysis for less than 2 min, followed by 1 h of reduction to release the peptides originally linked by disulfide bonds. It was shown that a strong base could be used as a catalyst for microwave-assisted protein hydrolysis, producing complementary sequence information to that generated by microwave-assisted acid hydrolysis. However, using either acid or base hydrolysis, amide bond breakages in small regions of the polypeptide chains of the model proteins (e.g., cytochrome c and lysozyme) were not detected. Dynamic light scattering measurement of the proteins solubilized in an acid or base indicated that protein-protein interaction or aggregation was not the cause of the failure to hydrolyze certain amide bonds. It was speculated that there were some unknown local structures that might play a role in preventing an acid or base from reacting with the peptide bonds therein. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

  14. An efficient algorithm for computing fixed length attractors based on bounded model checking in synchronous Boolean networks with biochemical applications.

    Science.gov (United States)

    Li, X Y; Yang, G W; Zheng, D S; Guo, W S; Hung, W N N

    2015-04-28

    Genetic regulatory networks are the key to understanding biochemical systems. One condition of the genetic regulatory network under different living environments can be modeled as a synchronous Boolean network. The attractors of these Boolean networks will help biologists to identify determinant and stable factors. Existing methods identify attractors based on a random initial state or the entire state simultaneously. They cannot identify the fixed length attractors directly. The complexity of including time increases exponentially with respect to the attractor number and length of attractors. This study used the bounded model checking to quickly locate fixed length attractors. Based on the SAT solver, we propose a new algorithm for efficiently computing the fixed length attractors, which is more suitable for large Boolean networks and numerous attractors' networks. After comparison using the tool BooleNet, empirical experiments involving biochemical systems demonstrated the feasibility and efficiency of our approach.

  15. Measurement and theory of hydrogen bonding contribution to isosteric DNA base pairs.

    Science.gov (United States)

    Khakshoor, Omid; Wheeler, Steven E; Houk, K N; Kool, Eric T

    2012-02-15

    We address the recent debate surrounding the ability of 2,4-difluorotoluene (F), a low-polarity mimic of thymine (T), to form a hydrogen-bonded complex with adenine in DNA. The hydrogen bonding ability of F has been characterized as small to zero in various experimental studies, and moderate to small in computational studies. However, recent X-ray crystallographic studies of difluorotoluene in DNA/RNA have indicated, based on interatomic distances, possible hydrogen bonding interactions between F and natural bases in nucleic acid duplexes and in a DNA polymerase active site. Since F is widely used to measure electrostatic contributions to pairing and replication, it is important to quantify the impact of this isostere on DNA stability. Here, we studied the pairing stability and selectivity of this compound and a closely related variant, dichlorotoluene deoxyriboside (L), in DNA, using both experimental and computational approaches. We measured the thermodynamics of duplex formation in three sequence contexts and with all possible pairing partners by thermal melting studies using the van't Hoff approach, and for selected cases by isothermal titration calorimetry (ITC). Experimental results showed that internal F-A pairing in DNA is destabilizing by 3.8 kcal/mol (van't Hoff, 37 °C) as compared with T-A pairing. At the end of a duplex, base-base interactions are considerably smaller; however, the net F-A interaction remains repulsive while T-A pairing is attractive. As for selectivity, F is found to be slightly selective for adenine over C, G, T by 0.5 kcal mol, as compared with thymine's selectivity of 2.4 kcal/mol. Interestingly, dichlorotoluene in DNA is slightly less destabilizing and slightly more selective than F, despite the lack of strongly electronegative fluorine atoms. Experimental data were complemented by computational results, evaluated at the M06-2X/6-31+G(d) and MP2/cc-pVTZ levels of theory. These computations suggest that the pairing energy of F to A

  16. Race-Ethnicity, Poverty, Urban Stressors, and Telomere Length in a Detroit Community-based Sample.

    Science.gov (United States)

    Geronimus, Arline T; Pearson, Jay A; Linnenbringer, Erin; Schulz, Amy J; Reyes, Angela G; Epel, Elissa S; Lin, Jue; Blackburn, Elizabeth H

    2015-06-01

    Residents of distressed urban areas suffer early aging-related disease and excess mortality. Using a community-based participatory research approach in a collaboration between social researchers and cellular biologists, we collected a unique data set of 239 black, white, or Mexican adults from a stratified, multistage probability sample of three Detroit neighborhoods. We drew venous blood and measured telomere length (TL), an indicator of stress-mediated biological aging, linking respondents' TL to their community survey responses. We regressed TL on socioeconomic, psychosocial, neighborhood, and behavioral stressors, hypothesizing and finding an interaction between poverty and racial-ethnic group. Poor whites had shorter TL than nonpoor whites; poor and nonpoor blacks had equivalent TL; and poor Mexicans had longer TL than nonpoor Mexicans. Findings suggest unobserved heterogeneity bias is an important threat to the validity of estimates of TL differences by race-ethnicity. They point to health impacts of social identity as contingent, the products of structurally rooted biopsychosocial processes. © American Sociological Association 2015.

  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. Push-out bond strength of different tricalcium silicate-based filling materials to root dentin

    Directory of Open Access Journals (Sweden)

    Jorge Henrique Stefaneli Marques

    2018-03-01

    Full Text Available Abstract: The aim of this study was to evaluate the bond strength of different triccalcium silicate cements to retrograde cavity using a push out test. Thirty maxillary central incisors were shaped using #80 hand files and sectioned transversally. Root slices were obtained from the apical 4 mm after eliminating the apical extremity. The specimens were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. The samples were divided into three groups according to the root-end filling material (n = 10: MTA Angelus, ProRoot MTA and Biodentine. A gutta-percha cone (#80 was tugged-back at the limit between the canal and the root-end cavity. The root-end cavity was filled and the gutta-percha cone was removed after complete setting of the materials. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and push out testing was performed at a crosshead speed of 1.0 mm/min. There was no statistically significant difference in resistance to push out by the materials tested (p > 0.01. MTA Angelus and ProRoot MTA showed predominantly mixed failure while Biodentine exhibited mixed and cohesive failures. The tricalcium silicate-based root-end filling materials showed similar bond strength retrograde cavity.

  19. Push-out bond strength of different tricalcium silicate-based filling materials to root dentin.

    Science.gov (United States)

    Stefaneli Marques, Jorge Henrique; Silva-Sousa, Yara Teresinha Corrêa; Rached-Júnior, Fuad Jacob Abi; Macedo, Luciana Martins Domingues de; Mazzi-Chaves, Jardel Francisco; Camilleri, Josette; Sousa-Neto, Manoel Damião

    2018-03-08

    The aim of this study was to evaluate the bond strength of different triccalcium silicate cements to retrograde cavity using a push out test. Thirty maxillary central incisors were shaped using #80 hand files and sectioned transversally. Root slices were obtained from the apical 4 mm after eliminating the apical extremity. The specimens were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. The samples were divided into three groups according to the root-end filling material (n = 10): MTA Angelus, ProRoot MTA and Biodentine. A gutta-percha cone (#80) was tugged-back at the limit between the canal and the root-end cavity. The root-end cavity was filled and the gutta-percha cone was removed after complete setting of the materials. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and push out testing was performed at a crosshead speed of 1.0 mm/min. There was no statistically significant difference in resistance to push out by the materials tested (p > 0.01). MTA Angelus and ProRoot MTA showed predominantly mixed failure while Biodentine exhibited mixed and cohesive failures. The tricalcium silicate-based root-end filling materials showed similar bond strength retrograde cavity.

  20. Impact of Sliding Window Length in Indoor Human Motion Modes and Pose Pattern Recognition Based on Smartphone Sensors

    Directory of Open Access Journals (Sweden)

    Gaojing Wang

    2018-06-01

    Full Text Available Human activity recognition (HAR is essential for understanding people’s habits and behaviors, providing an important data source for precise marketing and research in psychology and sociology. Different approaches have been proposed and applied to HAR. Data segmentation using a sliding window is a basic step during the HAR procedure, wherein the window length directly affects recognition performance. However, the window length is generally randomly selected without systematic study. In this study, we examined the impact of window length on smartphone sensor-based human motion and pose pattern recognition. With data collected from smartphone sensors, we tested a range of window lengths on five popular machine-learning methods: decision tree, support vector machine, K-nearest neighbor, Gaussian naïve Bayesian, and adaptive boosting. From the results, we provide recommendations for choosing the appropriate window length. Results corroborate that the influence of window length on the recognition of motion modes is significant but largely limited to pose pattern recognition. For motion mode recognition, a window length between 2.5–3.5 s can provide an optimal tradeoff between recognition performance and speed. Adaptive boosting outperformed the other methods. For pose pattern recognition, 0.5 s was enough to obtain a satisfactory result. In addition, all of the tested methods performed well.

  1. Comparative study of freshwater crayfish, Cherax spp. (crustaceae: decapoda: parastacidae) from Papua, Indonesia based on length-weight analysis

    Science.gov (United States)

    Hamidah, H.; Abinawanto, Bowolaksono, A.

    2017-07-01

    The freshwater crayfish is one of the most important fish species as the protein resources. Lake and rivers are the habitat of crayfish in Papua. Morphological characters of crayfish, such as color, total body lengths (L) and body weight (W) were influenced by the habitat. The purpose of the study, therefore, was to compare the total body length and body weight as well as the unique color of crayfish from Uter lake (Atinjo district), Seremuk river (Haha village), Baliem river (Pike village; Hubukiak district, Jayawijaya), and Baliem river (Wesaput village; Wesaput district). Length-weight (body length; LB versus wet weight; WWT) relationships were determined for male and female crayfish (Cherax spp.) The length-weight relationships of total individuals was W = 0,022215.L3,159. This regression differed significantly (R2 = 97.5 %) between locations. Both males and females exhibited positive allometric growth as statistical difference was observed in the mean of the wet weight and body length between males and females. Besides, Canonical function was subjected to determine population distribution based on length-weight data.

  2. Extrafibrillar collagen demineralization-based chelate-and-rinse technique bridges the gap between wet and dry dentin bonding.

    Science.gov (United States)

    Mai, Sui; Wei, Chin-Chuan; Gu, Li-Sha; Tian, Fu-Cong; Arola, Dwayne D; Chen, Ji-Hua; Jiao, Yang; Pashley, David H; Niu, Li-Na; Tay, Franklin R

    2017-07-15

    Limitations associated with wet-bonding led to the recent development of a selective demineralization strategy in which dentin was etched with a reduced concentration of phosphoric acid to create exclusive extrafibrillar demineralization of the collagen matrix. However, the use of acidic conditioners removes calcium via diffusion of very small hydronium ions into the intrafibrillar collagen water compartments. This defeats the purpose of limiting the conditioner to the extrafibrillar space to create a collagen matrix containing only intrafibrillar minerals to prevent collapse of the collagen matrix. The present work examined the use of polymeric chelators (the sodium salt of polyacrylic acid) of different molecular weights to selectively demineralize extrafibrillar dentin. These polymeric chelators exhibit different affinities for calcium ions (isothermal titration calorimetry), penetrated intrafibrillar dentin collagen to different extents based on their molecular sizes (modified size-exclusion chromatography), and preserve the dynamic mechanical properties of mineralized dentin more favorably compared with completely demineralized phosphoric acid-etched dentin (nanoscopical dynamic mechanical analysis). Scanning and transmission electron microscopy provided evidence for retention of intrafibrillar minerals in dentin surfaces conditioned with polymeric chelators. Microtensile bond strengths to wet-bonded and dry-bonded dentin conditioned with these polymeric chelators showed that the use of sodium salts of polyacrylic acid for chelating dentin prior to bonding did not result in significant decline in resin-dentin bond strength. Taken together, the findings led to the conclusion that a chelate-and-rinse conditioning technique based on extrafibrillar collagen demineralization bridges the gap between wet and dry dentin bonding. The chelate-and-rinse dental adhesive bonding concept differentiates from previous research in that it is based on the size

  3. CDKL5 regulates flagellar length and localizes to the base of the flagella in Chlamydomonas

    Science.gov (United States)

    Tam, Lai-Wa; Ranum, Paul T.; Lefebvre, Paul A.

    2013-01-01

    The length of Chlamydomonas flagella is tightly regulated. Mutations in four genes—LF1, LF2, LF3, and LF4—cause cells to assemble flagella up to three times wild-type length. LF2 and LF4 encode protein kinases. Here we describe a new gene, LF5, in which null mutations cause cells to assemble flagella of excess length. The LF5 gene encodes a protein kinase very similar in sequence to the protein kinase CDKL5. In humans, mutations in this kinase cause a severe form of juvenile epilepsy. The LF5 protein localizes to a unique location: the proximal 1 μm of the flagella. The proximal localization of the LF5 protein is lost when genes that make up the proteins in the cytoplasmic length regulatory complex (LRC)—LF1, LF2, and LF3—are mutated. In these mutants LF5p becomes localized either at the distal tip of the flagella or along the flagellar length, indicating that length regulation involves, at least in part, control of LF5p localization by the LRC. PMID:23283985

  4. Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent.

    Science.gov (United States)

    Kavitha, T; Attri, Pankaj; Venkatesu, Pannuru; Devi, R S Rama; Hofman, T

    2012-04-19

    Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R(4)N](+) with commonly used anion hydroxide [OH](-) were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R(4)N](+)[OH](-) are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH(3))(4)N](+)[OH](-) (TMAH), tetraethyl ammonium hydroxide [(C(2)H(5))(4)N](+)[OH](-) (TEAH), tetrapropyl ammonium hydroxide [(C(3)H(7))(4)N](+)[OH](-) (TPAH) and tetrabutyl ammonium hydroxide [(C(4)H(9))(4)N](+)[OH](-) (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (V(E)), the deviation in isentropic compressibility (Δκ(s)) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich-Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7.

  5. The Effect of Food-Simulating Agents on the Bond Strength of Hard Chairside Reline Materials to Denture Base Resin.

    Science.gov (United States)

    Fatemi, Farzaneh Sadat; Vojdani, Mahroo; Khaledi, Amir Ali Reza

    2018-06-08

    To investigate the influence of food-simulating agents on the shear bond strength between direct hard liners and denture base acrylic resin. In addition, mode of failure was evaluated. One hundred fifty cylindrical columns of denture base resin were fabricated and bonded to three types of hard reline materials (Hard GC Reline, Tokuyama Rebase II Fast, TDV Cold Liner Rebase). Specimens of each reline material were divided into five groups (n = 10) to undergo 12-day immersion in distilled water, 0.02 N citric acid aqueous solution, heptane, and 40% ethanol/water solution at 37°C. The control group was not immersed in any solution. The shear bond strength test was performed, and the failure mode was determined. Statistics were analyzed with two-way ANOVA and chi-square test (α = 0.05). Significant interaction was found between the hard liners and food simulating agents (p < 0.001). The shear bond strength of Tokuyama in 40% ethanol and TDV in heptane decreased significantly (p = 0.001, p < 0.001 respectively); however, none of the solutions could significantly affect the shear bond strength of Hard GC Reline (p = 0.208). The mixed failure mode occurred more frequently in Hard GC Reline compared with the other liners (p < 0.001) and was predominant in specimens with higher bond strength values (p = 0.012). Food simulating agents did not adversely affect the shear bond strength of Hard GC Reline; however, ethanol and heptane decreased the bond strength of Tokuyama and TDV, respectively. These findings may provide support to dentists to recommend restricted consumption of some foods and beverages for patients who have to use dentures relined with certain hard liners. © 2018 by the American College of Prosthodontists.

  6. Optical Path Length Calibration: A Standard Approach for Use in Absorption Cell-Based IR-Spectrometric Gas Analysis

    Directory of Open Access Journals (Sweden)

    Javis Anyangwe Nwaboh

    2014-01-01

    Full Text Available We employed a comparison method to determine the optical path length of gas cells which can be used in spectroscopic setup based on laser absorption spectroscopy or FTIR. The method is based on absorption spectroscopy itself. A reference gas cell, whose length is a priori known and desirably traceable to the international system of units (SI, and a gas mixture are used to calibrate the path length of a cell under test. By comparing spectra derived from pressure-dependent measurements on the two cells, the path length of the gas cell under test is determined. The method relies neither on the knowledge of the gas concentration nor on the line strength parameter of the probed transition which is very rarely traceable to the SI and of which the uncertainty is often relatively large. The method is flexible such that any infrared light source and infrared active molecule with isolated lines can be used. We elaborate on the method, substantiate the method by reporting results of this calibration procedure applied to multipass and single pass gas cells of lengths from 0.38 m to 21 m, and compare this to other methods. The relative combined uncertainty of the path length results determined using the comparison method was found to be in the ±0.4% range.

  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. 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.

  9. Taylor-plasticity-based analysis of length scale effects in void growth

    KAUST Repository

    Liu, Junxian

    2014-09-25

    We have studied the void growth problem by employing the Taylor-based strain gradient plasticity theories, from which we have chosen the following three, namely, the mechanism-based strain gradient (MSG) plasticity (Gao et al 1999 J. Mech. Phys. Solids 47 1239, Huang et al 2000 J. Mech. Phys. Solids 48 99-128), the Taylor-based nonlocal theory (TNT; 2001 Gao and Huang 2001 Int. J. Solids Struct. 38 2615) and the conventional theory of MSG (CMSG; Huang et al 2004 Int. J. Plast. 20 753). We have addressed the following three issues which occur when plastic deformation at the void surface is unconstrained. (1) Effects of elastic deformation. Elasticity is essential for cavitation instability. It is therefore important to guarantee that the gradient term entering the Taylor model is the effective plastic strain gradient instead of the total strain gradient. We propose a simple elastic-plastic decomposition method. When the void size approaches the minimum allowable initial void size related to the maximum allowable geometrically necessary dislocation density, overestimation of the flow stress due to the negligence of the elastic strain gradient is on the order of lεY/R0 near the void surface, where l, εY and R0 are, respectively, the intrinsic material length scale, the yield strain and the initial void radius. (2) MSG intrinsic inconsistency, which was initially mentioned in Gao et al (1999 J. Mech. Phys. Solids 47 1239) but has not been the topic of follow-up studies. We realize that MSG higher-order stress arises due to the linear-strain-field approximation within the mesoscale cell with a nonzero size, lε. Simple analysis shows that within an MSG mesoscale cell near the void surface, the difference between microscale and mesoscale strains is on the order of (lε/R0)2, indicating that when lε/R0 ∼ 1.0, the higher-order stress effect can make the MSG result considerably different from the TNT or CMSG results. (3) Critical condition for cavitation instability

  10. Modeling Wood Fibre Length in Black Spruce (Picea mariana (Mill. BSP Based on Ecological Land Classification

    Directory of Open Access Journals (Sweden)

    Elisha Townshend

    2015-09-01

    Full Text Available Effective planning to optimize the forest value chain requires accurate and detailed information about the resource; however, estimates of the distribution of fibre properties on the landscape are largely unavailable prior to harvest. Our objective was to fit a model of the tree-level average fibre length related to ecosite classification and other forest inventory variables depicted at the landscape scale. A series of black spruce increment cores were collected at breast height from trees in nine different ecosite groups within the boreal forest of northeastern Ontario, and processed using standard techniques for maceration and fibre length measurement. Regression tree analysis and random forests were used to fit hierarchical classification models and find the most important predictor variables for the response variable area-weighted mean stem-level fibre length. Ecosite group was the best predictor in the regression tree. Longer mean fibre-length was associated with more productive ecosites that supported faster growth. The explanatory power of the model of fitted data was good; however, random forests simulations indicated poor generalizability. These results suggest the potential to develop localized models linking wood fibre length in black spruce to landscape-level attributes, and improve the sustainability of forest management by identifying ideal locations to harvest wood that has desirable fibre characteristics.

  11. Variable length adjacent partitioning for PTS based PAPR reduction of OFDM signal

    International Nuclear Information System (INIS)

    Ibraheem, Zeyid T.; Rahman, Md. Mijanur; Yaakob, S. N.; Razalli, Mohammad Shahrazel; Kadhim, Rasim A.

    2015-01-01

    Peak-to-Average power ratio (PAPR) is a major drawback in OFDM communication. It leads the power amplifier into nonlinear region operation resulting into loss of data integrity. As such, there is a strong motivation to find techniques to reduce PAPR. Partial Transmit Sequence (PTS) is an attractive scheme for this purpose. Judicious partitioning the OFDM data frame into disjoint subsets is a pivotal component of any PTS scheme. Out of the existing partitioning techniques, adjacent partitioning is characterized by an attractive trade-off between cost and performance. With an aim of determining effects of length variability of adjacent partitions, we performed an investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with other partitioning schemes such as pseudorandom partitioning. Simulation results with different modulation and partitioning scenarios showed that fixed length adjacent partition had better performance compared to variable length adjacent partitioning. As expected, simulation results showed a slightly better performance of pseudorandom partitioning technique compared to fixed and variable adjacent partitioning schemes. However, as the pseudorandom technique incurs high computational complexities, adjacent partitioning schemes were still seen as favorable candidates for PAPR reduction

  12. Variable length adjacent partitioning for PTS based PAPR reduction of OFDM signal

    Energy Technology Data Exchange (ETDEWEB)

    Ibraheem, Zeyid T.; Rahman, Md. Mijanur; Yaakob, S. N.; Razalli, Mohammad Shahrazel; Kadhim, Rasim A. [School of Computer and Communication Engineering, Universiti Malaysia Perlis, 02600 Arau, Perlis (Malaysia)

    2015-05-15

    Peak-to-Average power ratio (PAPR) is a major drawback in OFDM communication. It leads the power amplifier into nonlinear region operation resulting into loss of data integrity. As such, there is a strong motivation to find techniques to reduce PAPR. Partial Transmit Sequence (PTS) is an attractive scheme for this purpose. Judicious partitioning the OFDM data frame into disjoint subsets is a pivotal component of any PTS scheme. Out of the existing partitioning techniques, adjacent partitioning is characterized by an attractive trade-off between cost and performance. With an aim of determining effects of length variability of adjacent partitions, we performed an investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with other partitioning schemes such as pseudorandom partitioning. Simulation results with different modulation and partitioning scenarios showed that fixed length adjacent partition had better performance compared to variable length adjacent partitioning. As expected, simulation results showed a slightly better performance of pseudorandom partitioning technique compared to fixed and variable adjacent partitioning schemes. However, as the pseudorandom technique incurs high computational complexities, adjacent partitioning schemes were still seen as favorable candidates for PAPR reduction.

  13. Molecular dynamics study of some non-hydrogen-bonding base pair DNA strands

    Science.gov (United States)

    Tiwari, Rakesh K.; Ojha, Rajendra P.; Tiwari, Gargi; Pandey, Vishnudatt; Mall, Vijaysree

    2018-05-01

    In order to elucidate the structural activity of hydrophobic modified DNA, the DMMO2-D5SICS, base pair is introduced as a constituent in different set of 12-mer and 14-mer DNA sequences for the molecular dynamics (MD) simulation in explicit water solvent. AMBER 14 force field was employed for each set of duplex during the 200ns production-dynamics simulation in orthogonal-box-water solvent by the Particle-Mesh-Ewald (PME) method in infinite periodic boundary conditions (PBC) to determine conformational parameters of the complex. The force-field parameters of modified base-pair were calculated by Gaussian-code using Hartree-Fock /ab-initio methodology. RMSD Results reveal that the conformation of the duplex is sequence dependent and the binding energy of the complex depends on the position of the modified base-pair in the nucleic acid strand. We found that non-bonding energy had a significant contribution to stabilising such type of duplex in comparison to electrostatic energy. The distortion produced within strands by such type of base-pair was local and destabilised the duplex integrity near to substitution, moreover the binding energy of duplex depends on the position of substitution of hydrophobic base-pair and the DNA sequence and strongly supports the corresponding experimental study.

  14. Estimation of Length and Order of Polynomial-based Filter Implemented in the Form of Farrow Structure

    Directory of Open Access Journals (Sweden)

    S. Vukotic

    2016-08-01

    Full Text Available Digital polynomial-based interpolation filters implemented using the Farrow structure are used in Digital Signal Processing (DSP to calculate the signal between its discrete samples. The two basic design parameters for these filters are number of polynomial-segments defining the finite length of impulse response, and order of polynomials in each polynomial segment. The complexity of the implementation structure and the frequency domain performance depend on these two parameters. This contribution presents estimation formulae for length and polynomial order of polynomial-based filters for various types of requirements including attenuation in stopband, width of transitions band, deviation in passband, weighting in passband/stopband.

  15. The Influence of No-Primer Adhesives and Anchor Pylons Bracket Bases on Shear Bond Strength of Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    Andrea Scribante

    2013-01-01

    Full Text Available Objective. The aim of this study was to compare the shear bond strength (SBS and adhesive remnant index (ARI scores of no-primer adhesives tested with two different bracket bases. Materials and Methods. 120 bovine permanent mandibular incisors were divided into 6 groups of 20 specimens. Two brackets (ODP with different bracket bases (anchor pylons and 80-gauge mesh were bonded to the teeth using a conventional adhesive (Transbond XT and two different no-primer adhesive (Ortho Cem; Heliosit systems. Groups were tested using an instron universal testing machine. SBS values were recorded. ARI scores were measured. SEM microphotographs were taken to evaluate the pattern of bracket bases. Statistical analysis was performed. ANOVA and Tukey tests were carried out for SBS values, whereas a chi-squared test was applied for ARI scores. Results. Highest bond strength values were reported with Transbond XT (with both pad designs, Ortho Cem bonded on anchor pylons and Heliosit on 80-gauge mesh. A higher frequency of ARI score of “3” was reported for Transbond XT groups. Other groups showed a higher frequency of ARI score “2” and “1.” Conclusion. Transbond XT showed the highest shear bond strength values with both pad designs.

  16. Vaporization enthalpies of imidazolium based ionic liquids. A thermogravimetric study of the alkyl chain length dependence

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Zaitsau, Dzmitry H.; Emel’yanenko, Vladimir N.; Ralys, Ricardas V.; Yermalayeu, Andrei V.; Schick, Christoph

    2012-01-01

    Highlights: ► Enthalpies of vaporization of ionic liquids were measured with thermogravimetry. ► We studied 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide. ► The linear alkyl chain length was 4, 6, 8, 10, 12, 14, 16, and 18 C-atoms. ► A linear dependence on the chain length of the alkyl-imidazolium cation was found. - Abstract: Vaporization enthalpies for a series of ten ionic liquids (ILs) 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide [C n mim][NTf 2 ], with the alkyl chain length n = 4, 6, 8, 10, 12, 14, 16, and 18 were determined using the thermogravimetric method. An internally consistent set of experimental data and vaporization enthalpies at 540 K was obtained. Vaporization enthalpies at 540 K have shown a linear dependence on the chain length of the alkyl-imidazolium cation in agreement with the experimental results measured previously with a quartz crystal microbalance. Ambiguity of Δ l g C pm o -values required for the extrapolation of experimental vaporization enthalpies to the reference temperature 298 K has been discussed.

  17. Is group singing special? Health, well-being and social bonds in community-based adult education classes.

    Science.gov (United States)

    Pearce, Eiluned; Launay, Jacques; Machin, Anna; Dunbar, Robin I M

    Evidence demonstrates that group singing improves health and well-being, but the precise mechanisms remain unknown. Given that cohesive social networks also positively influence health, we focus on the social aspects of singing, exploring whether improvements in health and well-being are mediated by stronger social bonds, both to the group as a whole (collective-bonding) and to individual classmates (relational-bonding). To do so, seven newly-formed community-based adult education classes (four singing, N =84, and three comparison classes studying creative writing or crafts, N =51) were followed over seven months. Self-report questionnaire data on mental and physical health, well-being, and social bonding were collected at Months 1, 3 and 7. We demonstrate that physical and mental health and satisfaction with life significantly improved over time in both conditions. Path analysis did not show any indirect effects via social bonding of Condition on health and well-being. However, higher collective-bonding at timepoint 3 significantly predicted increased flourishing, reduced anxiety and improved physical health independently of baseline levels. In contrast, relational-bonding showed no such effects, suggesting that it is feeling part of a group that particularly yields health and well-being benefits. Moreover, these results indicate that singing may not improve health and well-being more than other types of activities. Nonetheless, these findings encourage further work to refine our understanding of the social aspects of community-based adult education classes in promoting health, well-being and community cohesion.

  18. The role of hydrogen bonds in the melting points of sulfonate-based protic organic salts

    DEFF Research Database (Denmark)

    Luo, Jiangshui

    2016-01-01

    There are three main types of interactions inside organic salts - electrostatic interaction, hydrogen bonding and van der Waals force [1-4]. While van der Waals force is relatively weak, it is hydrogen bonding and particularly electrostatic interaction that determine the lattice energies of ionic...

  19. Shielding and mediating of hydrogen bonding in amide-based (macro)molecules

    NARCIS (Netherlands)

    Harings, J.A.W.

    2009-01-01

    Polymers are long chain molecules comprising continuously repeating building blocks, monomers, which are chemically linked via covalent bonds, for example the C-C bond in polyethylene. A distinction can be made in biopolymers that are made in nature and synthetic polymers that are produced by the

  20. Experiment-Based Sensitivity Analysis of Scaled Carbon-Fiber-Reinforced Elastomeric Isolators in Bonded Applications

    Directory of Open Access Journals (Sweden)

    Farshad Hedayati Dezfuli

    2016-01-01

    Full Text Available Fiber-reinforced elastomeric isolators (FREIs are a new type of elastomeric base isolation systems. Producing FREIs in the form of long laminated pads and cutting them to the required size significantly reduces the time and cost of the manufacturing process. Due to the lack of adequate information on the performance of FREIs in bonded applications, the goal of this study is to assess the performance sensitivity of 1/4-scale carbon-FREIs based on the experimental tests. The scaled carbon-FREIs are manufactured using a fast cold-vulcanization process. The effect of several factors including the vertical pressure, the lateral cyclic rate, the number of rubber layers, and the thickness of carbon fiber-reinforced layers are explored on the cyclic behavior of rubber bearings. Results show that the effect of vertical pressure on the lateral response of base isolators is negligible. However, decreasing the cyclic loading rate increases the lateral flexibility and the damping capacity. Additionally, carbon fiber-reinforced layers can be considered as a minor source of energy dissipation.

  1. School Nutrition Employees' Perceptions of Farm to School (FTS) Activities Differ Based on Management Type and FTS Participation Length

    Science.gov (United States)

    Kang, Sangwook; Arendt, Susan W.; Stokes, Nathan M.

    2016-01-01

    Purpose: The purpose of this study was to explore school nutrition employees' perceptions of FTS activities and whether the numbers of activities differ based on management type of school foodservice operation and length of FTS participation. Methods: The state with the most FTS programs from each of the eight national FTS regions was selected. A…

  2. Is compliance with hospital accreditation Associated with length of stay and acute readmission? A Danish nationwide population-base study

    DEFF Research Database (Denmark)

    Falstie-Jensen, Anne Mette; Nørgaard, Mette; Hollnagel, Erik

    2015-01-01

    OBJECTIVE: To examine the association between compliance with hospital accreditation and length of stay (LOS) and acute readmission (AR). DESIGN: A nationwide population-based follow-up study from November 2009 to December 2012. SETTING: Public, non-psychiatric Danish hospitals. PARTICIPANTS: In-...

  3. Evaluating the shear bond strength of enamel and dentin with or without etching: A comparative study between dimethacrylate-based and silorane-based adhesives

    Science.gov (United States)

    Hajizadeh, Hila; Nasseh, Atefeh; Rahmanpour, Naim

    2015-01-01

    Background Silorane-based composites and their specific self-etch adhesive were introduced to conquest the polymerization shrinkage of methacrylate-based composites. It has been shown that additional etching of enamel and dentin can improve the bond strength of self-etch methacrylate-based adhesives but this claim is not apparent about silorane-based adhesives. Our objective was to compare the shear bond strength (SBS) of enamel and dentin between silorane-based adhesive resin and a methacrylate-based resin with or without additional etching. Material and Methods 40 sound human premolars were prepared and divided into two groups: 1- Filtek P60 composite and Clearfil SE Bond adhesive; 2- Filtek P90 composite and Silorane adhesive. Each group divided into two subgroups: with or without additional etching. For additional etching, 37% acid phosphoric was applied before bonding procedure. A cylinder of the composite was bonded to the surface. After 24 hours storage and 500 thermo cycling between 5-55°C, shear bond strength was assessed with the cross head speed of 0.5 mm/min. Then, bonded surfaces were observed under stereomicroscope to determine the failure mode. Data were analyzed with two-way ANOVA and Fischer exact test. Results Shear bond strength of Filtek P60 composite was significantly higher than Filtek P90 composite both in enamel and dentin surfaces (Penamel or dentin for each of the composites (P>0.05). There was no interaction between composite type and additional etching (P>0.05). Failure pattern was mainly adhesive and no significant correlation was found between failure and composite type or additional etching (P>0.05). Conclusions Shear bond strength of methacrylate-based composite was significantly higher than silorane-based composite both in enamel and dentin surfaces and additional etching had no significant effect on shear bond strength in enamel or dentin for each of the composites. The mode of failure had no meaningful relation to the type of

  4. Ranking of Prokaryotic Genomes Based on Maximization of Sortedness of Gene Lengths.

    Science.gov (United States)

    Bolshoy, A; Salih, B; Cohen, I; Tatarinova, T

    How variations of gene lengths (some genes become longer than their predecessors, while other genes become shorter and the sizes of these factions are randomly different from organism to organism) depend on organismal evolution and adaptation is still an open question. We propose to rank the genomes according to lengths of their genes, and then find association between the genome rank and variousproperties, such as growth temperature, nucleotide composition, and pathogenicity. This approach reveals evolutionary driving factors. The main purpose of this study is to test effectiveness and robustness of several ranking methods. The selected method of evaluation is measuring of overall sortedness of the data. We have demonstrated that all considered methods give consistent results and Bubble Sort and Simulated Annealing achieve the highest sortedness. Also, Bubble Sort is considerably faster than the Simulated Annealing method.

  5. ESTIMATION OF BURSTS LENGTH AND DESIGN OF A FIBER DELAY LINE BASED OBS ROUTER

    Directory of Open Access Journals (Sweden)

    RICHA AWASTHI

    2017-03-01

    Full Text Available The demand for higher bandwidth is increasing day by day and this ever growing demand cannot be catered to with current electronic technology. Thus new communication technology like optical communication needs to be used. In the similar context OBS (optical burst switching is considered as next generation data transfer technology. In OBS information is transmitted in forms of optical bursts of variable lengths. However, contention among the bursts is a major problem in OBS system, and for contention resolution defection routing is mostly preferred. However, deflection routing increases delay. In this paper, it is shown that the arrival of very large bursts is rare event, and for moderate burst length the buffering of contending burst can provide very effective solution. However, in case of arrival of large bursts deflection can be used.

  6. Development of a thin film vitreous bond based composite ceramic coating for corrosion and abrasion services

    International Nuclear Information System (INIS)

    Franke, B.

    2003-01-01

    IPC has been involved with the Alberta Research Council in developing a vitreous bond (VB) - based composite ceramic fluoropolymer coating technology. Compared to the present state of the art which is based on a hard discontinuous phase (ceramic particles) suspended in a soft continuous matrix (fluoropolymer mix) the novelty of our approach consists of designing a composite system in which both the ceramic and the fluoropolymer phases are continuous. The ceramic matrix will provide the strength and the erosion resistance for the fluoropolymer matrix even at high temperatures. The ceramic formulation employed is not affected by temperatures up to 500 o F while the fluoropolymer matrix provides a corrosion protection seal for the ceramic matrix. The inherent flexibility of the polymer matrix will protect against brittle fractures that may develop by handling or impact. Therefore the composite coating is able to withstand the deformation of the substrate without chipping or disbanding. The fluoropolymer matrix also provides dry lubrication properties further enhancing the erosion resistance of the ceramic phase. The thickness of the coating is very thin, in the 25 to 100 micron range. In summary, the coating technology is able to provide the following features: Corrosion protection levels similar to those of fluoropolymer coatings; Erosion resistance similar to that of ceramic coatings; Price comparable to that of polymer coatings; Exceptional wear resistance properties; and Capability for coating complicated shapes internally or externally or both. This paper will discuss the theory and development of this new technology and the resultant coating and potential properties. (author)

  7. Assessment Of Possible Cycle Lengths For Fully-Ceramic Micro-Encapsulated Fuel-Based Light Water Reactor Concepts

    International Nuclear Information System (INIS)

    Sen, R. Sonat; Pope, Michael A.; Ougouag, Abderrafi M.; Pasamehmetoglu, Kemal; Venneri, Francesco

    2012-01-01

    The use of TRISO-particle-based dispersion fuel within SiC matrix and cladding materials has the potential to allow the design of extremely safe LWRs with failure-proof fuel. This paper examines the feasibility of LWR-like cycle length for such a low enriched uranium fuel with the imposed constraint of strictly retaining the original geometry of the fuel pins and assemblies. The motivation for retaining the original geometry is to provide the ability to incorporate the fuel 'as-is' into existing LWRs while retaining their thermal-hydraulic characteristics. The feasibility of using this fuel is assessed by looking at cycle lengths and fuel failure rates. Other considerations (e.g., safety parameters, etc.) were not considered at this stage of the study. The study includes the examination of different TRISO kernel diameters without changing the coating layer thicknesses. The study shows that a naive use of UO 2 results in cycle lengths too short to be practical for existing LWR designs and operational demands. Increasing fissile inventory within the fuel compacts shows that acceptable cycle lengths can be achieved. In this study, starting with the recognized highest packing fraction practically achievable (44%), higher enrichment, larger fuel kernel sizes, and the use of higher density fuels have been evaluated. The models demonstrate cycle lengths comparable to those of ordinary LWRs. As expected, TRISO particles with extremely large kernels are shown to fail under all considered scenarios. In contrast, the designs that do not depart too drastically from those of the nominal NGNP HTR fuel TRISO particles are shown to perform satisfactorily and display a high rates of survival under all considered scenarios. Finally, it is recognized that relaxing the geometry constraint will result in satisfactory cycle lengths even using UO 2 -loaded TRISO particles-based fuel with enrichment at or below 20 w/o.

  8. COGNAC: a web server for searching and annotating hydrogen-bonded base interactions in RNA three-dimensional structures.

    Science.gov (United States)

    Firdaus-Raih, Mohd; Hamdani, Hazrina Yusof; Nadzirin, Nurul; Ramlan, Effirul Ikhwan; Willett, Peter; Artymiuk, Peter J

    2014-07-01

    Hydrogen bonds are crucial factors that stabilize a complex ribonucleic acid (RNA) molecule's three-dimensional (3D) structure. Minute conformational changes can result in variations in the hydrogen bond interactions in a particular structure. Furthermore, networks of hydrogen bonds, especially those found in tight clusters, may be important elements in structure stabilization or function and can therefore be regarded as potential tertiary motifs. In this paper, we describe a graph theoretical algorithm implemented as a web server that is able to search for unbroken networks of hydrogen-bonded base interactions and thus provide an accounting of such interactions in RNA 3D structures. This server, COGNAC (COnnection tables Graphs for Nucleic ACids), is also able to compare the hydrogen bond networks between two structures and from such annotations enable the mapping of atomic level differences that may have resulted from conformational changes due to mutations or binding events. The COGNAC server can be accessed at http://mfrlab.org/grafss/cognac. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  9. Condition-dependent female preference for male genitalia length is based on male reproductive tactics.

    Science.gov (United States)

    Hernandez-Jimenez, Armando; Rios-Cardenas, Oscar

    2017-12-06

    There is extensive morphological variation of male genitalia across animals with internal fertilization, even among closely related species. Most studies attempting to explain this extraordinary diversity have focused on processes that occur post-copula (e.g. sperm competition, cryptic female choice). Only a few studies have focused on the pre-copula process of female preference. In addition, the extent to which this variation could be associated with the use of different reproductive tactics has yet to be explored. Here, we show that female preference for male genitalia length in two livebearing fishes depends on the type of reproductive tactic of the males being evaluated as well as the body condition of the female. In a species where all males coax females to acquire matings (courters), females preferred males with short genitalia. In a species with genetically influenced alternative reproductive tactics (courter males that only court and produce courter sons, sneaker males that use the coercive tactic of sneak chase and produce sneaker sons), female preference depended on an interaction between male tactic and female condition: females in good condition preferred courter males with short genitalia, and sneaker males with long genitalia. Our results suggest that female preference for male traits favourable to their sons may be an important factor contributing to the diversification of male genitalia. Despite the contrasting selection for genitalia length that our female preference tests suggest, we found no significant differences in genitalia length between coaxing (courters) and coercive (sneakers) males. Our study represents a starting point to more clearly understand the role of alternative reproductive tactics and variation in female mate preference in the evolution of male genitalia. © 2017 The Author(s).

  10. An IEEE 802.3 Compatible Real Time Medium Access Control with Length-based Priority

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethernet frame, message-oriented dynamic priority mechanism is established. Prioritized medium access control operates under a so-called block mode in event of collisions.High priority messages have a chance to preempt block status incurred by low priority ones. By this means, the new MAC provides a conditional deterministic real time performance beyond a statistical one. Experiments demonstrate effectiveness and attractiveness of the proposed scheme. Moreover, this new MAC is completely compatible with IEEE802.3.

  11. Image steganography based on 2k correction and coherent bit length

    Science.gov (United States)

    Sun, Shuliang; Guo, Yongning

    2014-10-01

    In this paper, a novel algorithm is proposed. Firstly, the edge of cover image is detected with Canny operator and secret data is embedded in edge pixels. Sorting method is used to randomize the edge pixels in order to enhance security. Coherent bit length L is determined by relevant edge pixels. Finally, the method of 2k correction is applied to achieve better imperceptibility in stego image. The experiment shows that the proposed method is better than LSB-3 and Jae-Gil Yu's in PSNR and capacity.

  12. Microstructure of bonding interface for resistance welding of Zr-based metallic glass sheets

    International Nuclear Information System (INIS)

    Kuroda, Toshio; Ikeuchi, Kenji; Shimada, Masahiro; Kobayashi, Akira; Kimura, Hisamichi; Inoue, Akihisa

    2009-01-01

    Resistance welding of Zr 55 Cu 30 Al 10 Ni 5 metallic glass sheets was investigated at 723 K in a supercooled liquid region. The welding time was changed from 5 s to 20 s at 723 K. The joint interface of the metallic glass was no defect and no crack. X-ray diffraction technique of the bonding interface of specimens was performed. The specimens showed halo patterns showing existence of only glassy phase, when the welding time was 5 s and 10 s. X-ray diffraction patterns of specimen bonded for 20 s showed crystalline peaks with halo patterns for the welding for 20 s. The crystalline phase at the bonding interface was small. Transmission electron micrograph at the bonding interface showed nanostructures of NiZr 2 and Al 5 Ni 3 Zr 2 . (author)

  13. Retentive Shear Strengths of Various Bonding Attachment Bases: An in vitro Study

    Directory of Open Access Journals (Sweden)

    Abhishek Goyal

    2013-01-01

    Conclusion: Gemini brackets provided the best bond strengths clinically, followed by Mini Diagonali, Nu-Edge, Mini Twin, Mini Diamond and the Sapphire brackets in decreasing order as measured using the Weibull analysis.

  14. Bond Strength Mechanism of Fly Ash Based Geopolymer Mortars: A Review

    Science.gov (United States)

    Zailani, W. W. A.; Abdullah, M. M. A. B.; Razak, R. A.; Zainol, M. R. R. M. A.; Tahir, M. F. M.

    2017-11-01

    Geopolymer possess many excellent properties such as high compressive and bond strength, long term durability, better acid resistance and also known as a “Sustainable Material” due to its low carbon emission and low energy consumption. Thus, it is a good opportunity to develop and explore not only for cement and concrete but also as geopolymeric repair materials. This reviews showed that good bonding properties between geopolymeric repair material and concrete substrate is important in order to acquire an enhanced resistance against penetration of harmful substances and avoiding respalling of the repair material by understanding the bonding behaviour. Bond strength depends to the properties of the repair materials itself and also the surface preparations of concrete substrate.

  15. Effect of the Channel Length on the Transport Characteristics of Transistors Based on Boron-Doped Graphene Ribbons

    Directory of Open Access Journals (Sweden)

    Paolo Marconcini

    2018-04-01

    Full Text Available Substitutional boron doping of devices based on graphene ribbons gives rise to a unipolar behavior, a mobility gap, and an increase of the I O N / I O F F ratio of the transistor. Here we study how this effect depends on the length of the doped channel. By means of self-consistent simulations based on a tight-binding description and a non-equilibrium Green’s function approach, we demonstrate a promising increase of the I O N / I O F F ratio with the length of the channel, as a consequence of the different transport regimes in the ON and OFF states. Therefore, the adoption of doped ribbons with longer aspect ratios could represent a significant step toward graphene-based transistors with an improved switching behavior.

  16. Effect of surface treatments on the bond strength of soft denture lining materials to an acrylic resin denture base.

    Science.gov (United States)

    Gundogdu, Mustafa; Yesil Duymus, Zeynep; Alkurt, Murat

    2014-10-01

    Adhesive failure between acrylic resin and resilient liner material is commonly encountered in clinical practice. The purpose of this study was to evaluate the effect of different surface treatments on the bond strength of 2 different resilient lining materials to an acrylic resin denture base. Ninety-six dumbbell-shaped specimens were fabricated from heat-polymerized acrylic resin, and 3 mm of the material was cut from the thin midsection. The specimens were divided into 6 groups according to their surface treatments: no surface treatment (control group), 36% phosphoric acid etching (acid group), erbium:yttrium-aluminum-garnet (Er:YAG) laser (laser group), airborne-particle abrasion with 50-μm Al2O3 particles (abrasion group), an acid+laser group, and an abrasion+laser group. The specimens in each group were divided into 2 subgroups according to the resilient lining material used: heat-polymerized silicone based resilient liner (Molloplast B) and autopolymerized silicone-based resilient liner (Ufi Gel P). After all of the specimens had been polymerized, they were stored in distilled water at 37°C for 1 week. A tensile bond strength test was then performed. Data were analyzed with a 2-way ANOVA, and the Sidak multiple comparison test was used to identify significant differences (α=.05). The effects of the surface treatments and resilient lining materials on the surface of the denture base resin were examined with scanning electron microscopy. The tensile bond strength was significantly different between Molloplast B and Ufi Gel P (P<.001). The specimens of the acid group had the highest tensile bond strength, whereas those of the abrasion group had the lowest tensile bond strength. The scanning electron microscopy observations showed that the application of surface treatments modified the surface of the denture base resin. Molloplast B exhibited significantly higher bond strength than Ufi Gel P. Altering the surface of the acrylic resin denture base with 36

  17. Comparative evaluation of tensile bond strength of silicone-based denture liners after thermocycling and surface treatment.

    Science.gov (United States)

    Kaur, Harsimran; Datta, Kusum

    2015-01-01

    To examine, evaluate, and compare the tensile bond strength of two silicone-based liners; one autopolymerizing and one heat cured, when treated with different chemical etchants to improve their adhesion with denture base resin. Hundred and sixty test specimens of heat-cured polymethyl methacrylate (PMMA) were fabricated; out of which 80 specimens were tested for tensile bond strength after bonding it to autopolymerizing resilient liner (Ufigel P) and rest 80 to heat-cured resilient liner (Molloplast B). Each main group was further divided into four subgroups of 20 specimens each, one to act as a control and three were subjected to surface treatment with different chemical etchants namely dichloromethane, MMA monomer, and chloroform. The two silicone-based denture liners were processed between 2 PMMA specimens (10 mm × 10 mm × 40 mm) in the space provided by a spacer of 3 mm, thermocycled (5-55°C) for 500 cycles, and then their tensile strength measurements were done in the universal testing machine. One-way ANOVA technique showed a highly significant difference in the mean tensile bond strength values for all the groups. The Student's t-test computed values of statistics for the compared groups were greater than the critical values both at 5% and at 1% levels. Surface treatment of denture base resin with chemical etchants prior to the application of silicone-based liner (Ufigel P and Molloplast-B) increased the tensile bond strength. The increase was the highest with specimens subjected to 180 s of MMA surface treatment and the lowest with control group specimens.

  18. Comparative evaluation of tensile bond strength of silicone-based denture liners after thermocycling and surface treatment

    Directory of Open Access Journals (Sweden)

    Harsimran Kaur

    2015-01-01

    Full Text Available Purpose: To examine, evaluate, and compare the tensile bond strength of two silicone-based liners; one autopolymerizing and one heat cured, when treated with different chemical etchants to improve their adhesion with denture base resin. Materials and Methods: Hundred and sixty test specimens of heat-cured polymethyl methacrylate (PMMA were fabricated; out of which 80 specimens were tested for tensile bond strength after bonding it to autopolymerizing resilient liner (Ufigel P and rest 80 to heat-cured resilient liner (Molloplast B. Each main group was further divided into four subgroups of 20 specimens each, one to act as a control and three were subjected to surface treatment with different chemical etchants namely dichloromethane, MMA monomer, and chloroform. The two silicone-based denture liners were processed between 2 PMMA specimens (10 mm × 10 mm × 40 mm in the space provided by a spacer of 3 mm, thermocycled (5-55°C for 500 cycles, and then their tensile strength measurements were done in the universal testing machine. Results: One-way ANOVA technique showed a highly significant difference in the mean tensile bond strength values for all the groups. The Student′s t-test computed values of statistics for the compared groups were greater than the critical values both at 5% and at 1% levels. Conclusion: Surface treatment of denture base resin with chemical etchants prior to the application of silicone-based liner (Ufigel P and Molloplast-B increased the tensile bond strength. The increase was the highest with specimens subjected to 180 s of MMA surface treatment and the lowest with control group specimens.

  19. Reconfigurable Diodes Based on Vertical WSe2 Transistors with van der Waals Bonded Contacts.

    Science.gov (United States)

    Avsar, Ahmet; Marinov, Kolyo; Marin, Enrique Gonzalez; Iannaccone, Giuseppe; Watanabe, Kenji; Taniguchi, Takashi; Fiori, Gianluca; Kis, Andras

    2018-05-01

    New device concepts can increase the functionality of scaled electronic devices, with reconfigurable diodes allowing the design of more compact logic gates being one of the examples. In recent years, there has been significant interest in creating reconfigurable diodes based on ultrathin transition metal dichalcogenide crystals due to their unique combination of gate-tunable charge carriers, high mobility, and sizeable band gap. Thanks to their large surface areas, these devices are constructed under planar geometry and the device characteristics are controlled by electrostatic gating through rather complex two independent local gates or ionic-liquid gating. In this work, similar reconfigurable diode action is demonstrated in a WSe 2 transistor by only utilizing van der Waals bonded graphene and Co/h-BN contacts. Toward this, first the charge injection efficiencies into WSe 2 by graphene and Co/h-BN contacts are characterized. While Co/h-BN contact results in nearly Schottky-barrier-free charge injection, graphene/WSe 2 interface has an average barrier height of ≈80 meV. By taking the advantage of the electrostatic transparency of graphene and the different work-function values of graphene and Co/h-BN, vertical devices are constructed where different gate-tunable diode actions are demonstrated. This architecture reveals the opportunities for exploring new device concepts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Stable Au–C bonds to the substrate for fullerene-based nanostructures

    Directory of Open Access Journals (Sweden)

    Taras Chutora

    2017-05-01

    Full Text Available We report on the formation of fullerene-derived nanostructures on Au(111 at room temperature and under UHV conditions. After low-energy ion sputtering of fullerene films deposited on Au(111, bright spots appear at the herringbone corner sites when measured using a scanning tunneling microscope. These features are stable at room temperature against diffusion on the surface. We carry out DFT calculations of fullerene molecules having one missing carbon atom to simulate the vacancies in the molecules resulting from the sputtering process. These modified fullerenes have an adsorption energy on the Au(111 surface that is 1.6 eV higher than that of C60 molecules. This increased binding energy arises from the saturation by the Au surface of the bonds around the molecular vacancy defect. We therefore interpret the observed features as adsorbed fullerene-derived molecules with C vacancies. This provides a pathway for the formation of fullerene-based nanostructures on Au at room temperature.

  1. Carboxymethyl chitosan based nanocomposites containing chemically bonded quantum dots and magnetic nanoparticles

    Science.gov (United States)

    Ding, Yongling; Yin, Hong; Chen, Rui; Bai, Ru; Chen, Chunying; Hao, Xiaojuan; Shen, Shirley; Sun, Kangning; Liu, Futian

    2018-03-01

    A biocompatible nanocomposite consisting of fluorescent quantum dots (QDs) and magnetic nanoparticles (MNPs) has been constructed via carboxymethyl chitosan (CMCS), resulting in magnetic-fluorescent nanoparticles (MFNPs). In these MFNPs, QDs and MNPs are successfully conjugated via covalent bonds onto the surface of CMCS. The composite retains favorable magnetic and fluorescent properties and shows a good colloidal stability in physiological environments. Folate (FA) as a specific targeting ligand was further incorporated into the nanocomposites to form a delivery vehicle with a targeting function. The therapeutic activity was achieved by loading chemotherapeutic drug doxorubicin (DOX) through electrostatic and hydrophobic interactions. The cumulative DOX release profile shows pH-sensitive. Both flow cytometry analysis and confocal laser scanning microscopic observation suggested that these nanocomposites were uptaken by cancer cells via FA receptor-mediated endocytosis pathway. In summary, the CMCS based nanocomposites developed in this work have a great potential for effective cancer-targeting and drug delivery, as well as in situ cellular imaging.

  2. Ultrasonic Fingerprint Sensor With Transmit Beamforming Based on a PMUT Array Bonded to CMOS Circuitry.

    Science.gov (United States)

    Jiang, Xiaoyue; Tang, Hao-Yen; Lu, Yipeng; Ng, Eldwin J; Tsai, Julius M; Boser, Bernhard E; Horsley, David A

    2017-09-01

    In this paper, we present a single-chip 65 ×42 element ultrasonic pulse-echo fingerprint sensor with transmit (TX) beamforming based on piezoelectric micromachined ultrasonic transducers directly bonded to a CMOS readout application-specific integrated circuit (ASIC). The readout ASIC was realized in a standard 180-nm CMOS process with a 24-V high-voltage transistor option. Pulse-echo measurements are performed column-by-column in sequence using either one column or five columns to TX the ultrasonic pulse at 20 MHz. TX beamforming is used to focus the ultrasonic beam at the imaging plane where the finger is located, increasing the ultrasonic pressure and narrowing the 3-dB beamwidth to [Formula: see text], a factor of 6.4 narrower than nonbeamformed measurements. The surface of the sensor is coated with a poly-dimethylsiloxane (PDMS) layer to provide good acoustic impedance matching to skin. Scanning laser Doppler vibrometry of the PDMS surface was used to map the ultrasonic pressure field at the imaging surface, demonstrating the expected increase in pressure, and reduction in beamwidth. Imaging experiments were conducted using both PDMS phantoms and real fingerprints. The average image contrast is increased by a factor of 1.5 when beamforming is used.

  3. Nonorthogonal orbital based N-body reduced density matrices and their applications to valence bond theory. I. Hamiltonian matrix elements between internally contracted excited valence bond wave functions

    Science.gov (United States)

    Chen, Zhenhua; Chen, Xun; Wu, Wei

    2013-04-01

    In this series, the n-body reduced density matrix (n-RDM) approach for nonorthogonal orbitals and their applications to ab initio valence bond (VB) methods are presented. As the first paper of this series, Hamiltonian matrix elements between internally contracted VB wave functions are explicitly provided by means of nonorthogonal orbital based RDM approach. To this end, a more generalized Wick's theorem, called enhanced Wick's theorem, is presented both in arithmetical and in graphical forms, by which the deduction of expressions for the matrix elements between internally contracted VB wave functions is dramatically simplified, and the matrix elements are finally expressed in terms of tensor contractions of electronic integrals and n-RDMs of the reference VB self-consistent field wave function. A string-based algorithm is developed for the purpose of evaluating n-RDMs in an efficient way. Using the techniques presented in this paper, one is able to develop new methods and efficient algorithms for nonorthogonal orbital based many-electron theory much easier than by use of the first quantized formulism.

  4. Adjustable, short focal length permanent-magnet quadrupole based electron beam final focus system

    Directory of Open Access Journals (Sweden)

    J. K. Lim

    2005-07-01

    Full Text Available Advanced high-brightness beam applications such as inverse-Compton scattering (ICS depend on achieving of ultrasmall spot sizes in high current beams. Modern injectors and compressors enable the production of high-brightness beams having needed short bunch lengths and small emittances. Along with these beam properties comes the need to produce tighter foci, using stronger, shorter focal length optics. An approach to creating such strong focusing systems using high-field, small-bore permanent-magnet quadrupoles (PMQs is reported here. A final-focus system employing three PMQs, each composed of 16 neodymium iron boride sectors in a Halbach geometry has been installed in the PLEIADES ICS experiment. The field gradient in these PMQs is 560   T/m, the highest ever reported in a magnetic optics system. As the magnets are of a fixed field strength, the focusing system is tuned by adjusting the position of the three magnets along the beam line axis, in analogy to familiar camera optics. This paper discusses the details of the focusing system, simulation, design, fabrication, and experimental procedure in creating ultrasmall beams at PLEIADES.

  5. 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

  6. Existence of both blue-shifting hydrogen bond and Lewis acid-base interaction in the complexes of carbonyls and thiocarbonyls with carbon dioxide.

    Science.gov (United States)

    Nguyen, Tien Trung; Nguyen, Phi Hung; Tran, Thanh Hue; Minh, Tho Nguyen

    2011-08-21

    In this study, 16 gas phase complexes of the pairs of XCHZ and CO(2) (X = F, Cl, Br; Z = O, S) have been identified. Interaction energies calculated at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ level including both BSSE and ZPE corrections range from -5.6 to -10.5 kJ mol(-1) for XCHOCO(2) and from -5.7 to -9.1 kJ mol(-1) for XCHS···CO(2). Substitution of one H atom by one halogen in formaldehyde and thioformaldehyde reduces the interaction energy of XCHZ···CO(2), while a CH(3) substitution increases the interaction energy of both CH(3)CHO···CO(2) and CH(3)CHS···CO(2). NBO and AIM analyses also point out that the strength of Lewis acid-base interactions decreases going from >C1=S3···C6 to >C1=O3C6 and to >C1-X4···C6. This result suggests the higher capacity of solubility of thiocarbonyl compounds in scCO(2), providing an enormous potential application for designing CO(2)-philic materials based on the >C=S functional group in competition with >C=O. The Lewis acid-base interaction of the types >C=S···C, >C-Cl···C and >C-Br···C is demonstrated for the first time. The contribution of the hydrogen bonding interaction to the total interaction energy is larger for XCHS···CO(2) than for XCHO···CO(2). Upon complexation, a contraction of the C1-H2 bond length and a blue shift of its stretching frequency have been observed, as compared to the isolated monomer, indicating the existence of a blue-shifting hydrogen bond in all complexes examined. Calculated results also lend further support for the viewpoint that when acting as proton donor, a C-H bond having a weaker polarization will induce a stronger distance contraction and frequency blue shift upon complexation, and vice versa.

  7. Effect of a bonding agent on in vitro biochemical activities of remineralizing resin-based calcium phosphate cements.

    Science.gov (United States)

    Dickens, Sabine H; Flaim, Glenn M

    2008-09-01

    To test whether fluoride in a resin-based Ca-PO4 ion releasing cement or coating with an acidic bonding agent for improved adhesion compromised the cement remineralization potential. Cements were formulated without fluoride (Cement A) or with fluoride (Cement B). The treatment groups were A=Cement A; A2=Cement A+bonding agent; B=Cement B; B2=Cement B+bonding agent. The calcium, phosphate, and fluoride ion release in saliva-like solution (SLS) was determined from hardened cement disks without or with a coating of bonding agent. For the remineralization, two cavities were prepared in dentin of extracted human molars and demineralized. One cavity received composite resin (control); the other received treatment A, A2, B or B2. After 6 week incubation in SLS, 180 microm cross-sections were cut. The percentage remineralization was determined by transverse microradiography comparing the dentin mineral density under the cement to that under the control. The percentage of remineralization (mean+/-S.D.) was A (39+/-14)=B (37+/-18), A2 (23+/-13), B2 (14+/-7). Two-way analysis of variance (ANOVA) and Holm-Sidak test showed a significant effect from the presence of bonding agent (p0.05). The ion solution concentrations of all groups showed undersaturation with respect to dicalcium phosphate dihydrate and calcium fluoride and supersaturation for fluorapatite and hydroxyapatite suggesting a positive remineralization potential. Compared to the control all treatments resulted in mineral increase. The remineralization was negatively affected by the presence of the bonding agent.

  8. A computational approach for the annotation of hydrogen-bonded base interactions in crystallographic structures of the ribozymes

    Energy Technology Data Exchange (ETDEWEB)

    Hamdani, Hazrina Yusof, E-mail: hazrina@mfrlab.org [School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi (Malaysia); Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bertam, Kepala Batas (Malaysia); Artymiuk, Peter J., E-mail: p.artymiuk@sheffield.ac.uk [Dept. of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, S10 T2N Sheffield (United Kingdom); Firdaus-Raih, Mohd, E-mail: firdaus@mfrlab.org [School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi (Malaysia)

    2015-09-25

    A fundamental understanding of the atomic level interactions in ribonucleic acid (RNA) and how they contribute towards RNA architecture is an important knowledge platform to develop through the discovery of motifs from simple arrangements base pairs, to more complex arrangements such as triples and larger patterns involving non-standard interactions. The network of hydrogen bond interactions is important in connecting bases to form potential tertiary motifs. Therefore, there is an urgent need for the development of automated methods for annotating RNA 3D structures based on hydrogen bond interactions. COnnection tables Graphs for Nucleic ACids (COGNAC) is automated annotation system using graph theoretical approaches that has been developed for the identification of RNA 3D motifs. This program searches for patterns in the unbroken networks of hydrogen bonds for RNA structures and capable of annotating base pairs and higher-order base interactions, which ranges from triples to sextuples. COGNAC was able to discover 22 out of 32 quadruples occurrences of the Haloarcula marismortui large ribosomal subunit (PDB ID: 1FFK) and two out of three occurrences of quintuple interaction reported by the non-canonical interactions in RNA (NCIR) database. These and several other interactions of interest will be discussed in this paper. These examples demonstrate that the COGNAC program can serve as an automated annotation system that can be used to annotate conserved base-base interactions and could be added as additional information to established RNA secondary structure prediction methods.

  9. A computational approach for the annotation of hydrogen-bonded base interactions in crystallographic structures of the ribozymes

    International Nuclear Information System (INIS)

    Hamdani, Hazrina Yusof; Artymiuk, Peter J.; Firdaus-Raih, Mohd

    2015-01-01

    A fundamental understanding of the atomic level interactions in ribonucleic acid (RNA) and how they contribute towards RNA architecture is an important knowledge platform to develop through the discovery of motifs from simple arrangements base pairs, to more complex arrangements such as triples and larger patterns involving non-standard interactions. The network of hydrogen bond interactions is important in connecting bases to form potential tertiary motifs. Therefore, there is an urgent need for the development of automated methods for annotating RNA 3D structures based on hydrogen bond interactions. COnnection tables Graphs for Nucleic ACids (COGNAC) is automated annotation system using graph theoretical approaches that has been developed for the identification of RNA 3D motifs. This program searches for patterns in the unbroken networks of hydrogen bonds for RNA structures and capable of annotating base pairs and higher-order base interactions, which ranges from triples to sextuples. COGNAC was able to discover 22 out of 32 quadruples occurrences of the Haloarcula marismortui large ribosomal subunit (PDB ID: 1FFK) and two out of three occurrences of quintuple interaction reported by the non-canonical interactions in RNA (NCIR) database. These and several other interactions of interest will be discussed in this paper. These examples demonstrate that the COGNAC program can serve as an automated annotation system that can be used to annotate conserved base-base interactions and could be added as additional information to established RNA secondary structure prediction methods

  10. A micromechanical approach of suffusion based on a length scale analysis of the grain detachment and grain transport processes.

    Science.gov (United States)

    Wautier, Antoine; Bonelli, Stéphane; Nicot, François

    2017-06-01

    Suffusion is the selective erosion of the finest particles of a soil subjected to an internal flow. Among the four types of internal erosion and piping identified today, suffusion is the least understood. Indeed, there is a lack of micromechanical approaches for identifying the critical microstructural parameters responsible for this process. Based on a discrete element modeling of non cohesive granular assemblies, specific micromechanical tools are developed in a unified framework to account for the two first steps of suffusion, namely the grain detachment and the grain transport processes. Thanks to the use of an enhanced force chain definition and autocorrelation functions the typical lengths scales associated with grain detachment are characterized. From the definition of transport paths based on a graph description of the pore space the typical lengths scales associated with grain transport are recovered. For a uniform grain size distribution, a separation of scales between these two processes exists for the finest particles of a soil

  11. Variable RF capacitor based on a-Si:H (P-doped) multi-length cantilevers

    International Nuclear Information System (INIS)

    Fu, Y Q; Milne, S B; Luo, J K; Flewitt, A J; Wang, L; Miao, J M; Milne, W I

    2006-01-01

    A variable RF capacitor with a-Si:H (doped with phosphine) cantilevers as the top electrode were designed and fabricated. Because the top multi-cantilever electrodes have different lengths, increasing the applied voltage pulled down the cantilever beams sequentially, thus realizing a gradual increase of the capacitance with the applied voltage. A high-k material, H f O 2 , was used as an insulating layer to increase the tuning range of the capacitance. The measured capacitance from the fabricated capacitor was much lower and the pull-in voltage was much higher than those from theoretical analysis because of incomplete contact of the two electrodes, existence of film differential stresses and charge injection effect. Increase of sweeping voltage rate could significantly shift the pull-in voltage to higher values due to the charge injection mechanisms

  12. The Prediction of Length-of-day Variations Based on Gaussian Processes

    Science.gov (United States)

    Lei, Y.; Zhao, D. N.; Gao, Y. P.; Cai, H. B.

    2015-01-01

    Due to the complicated time-varying characteristics of the length-of-day (LOD) variations, the accuracies of traditional strategies for the prediction of the LOD variations such as the least squares extrapolation model, the time-series analysis model, and so on, have not met the requirements for real-time and high-precision applications. In this paper, a new machine learning algorithm --- the Gaussian process (GP) model is employed to forecast the LOD variations. Its prediction precisions are analyzed and compared with those of the back propagation neural networks (BPNN), general regression neural networks (GRNN) models, and the Earth Orientation Parameters Prediction Comparison Campaign (EOP PCC). The results demonstrate that the application of the GP model to the prediction of the LOD variations is efficient and feasible.

  13. 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

  14. Deuterium isotope effects and fractionation factors of hydrogen-bonded A:T base pairs of DNA

    International Nuclear Information System (INIS)

    Vakonakis, Ioannis; Salazar, Miguel; Kang, Mijeong; Dunbar, Kim R.; Li Wang, Andy C.

    2003-01-01

    Deuterium isotope effects and fractionation factors of N1...H3-N3 hydrogen bonded Watson-Crick A:T base pairs of two DNA dodecamers are presented here. Specifically, two-bond deuterium isotope effects on the chemical shifts of 13 C2 and 13 C4, 2 Δ 13 C2 and 2 Δ 13 C4, and equilibrium deuterium/protium fractionation factors of H3, Φ, were measured and seen to correlate with the chemical shift of the corresponding imino proton, δ H3 . Downfield-shifted imino protons associated with larger values of 2 Δ 13 C2 and 2 Δ 13 C4 and smaller Φ values, which together suggested that the effective H3-N3 vibrational potentials were more anharmonic in the stronger hydrogen bonds of these DNA molecules. We anticipate that 2 Δ 13 C2, 2 Δ 13 C4 and Φ values can be useful gauges of hydrogen bond strength of A:T base pairs

  15. NMR scalar couplings across Watson–Crick base pair hydrogen bonds in DNA observed by transverse relaxation-optimized spectroscopy

    Science.gov (United States)

    Pervushin, Konstantin; Ono, Akira; Fernández, César; Szyperski, Thomas; Kainosho, Masatsune; Wüthrich, Kurt

    1998-01-01

    This paper describes the NMR observation of 15N—15N and 1H—15N scalar couplings across the hydrogen bonds in Watson–Crick base pairs in a DNA duplex, hJNN and hJHN. These couplings represent new parameters of interest for both structural studies of DNA and theoretical investigations into the nature of the hydrogen bonds. Two dimensional [15N,1H]-transverse relaxation-optimized spectroscopy (TROSY) with a 15N-labeled 14-mer DNA duplex was used to measure hJNN, which is in the range 6–7 Hz, and the two-dimensional hJNN-correlation-[15N,1H]-TROSY experiment was used to correlate the chemical shifts of pairs of hydrogen bond-related 15N spins and to observe, for the first time, hJHN scalar couplings, with values in the range 2–3.6 Hz. TROSY-based studies of scalar couplings across hydrogen bonds should be applicable for large molecular sizes, including protein-bound nucleic acids. PMID:9826668

  16. 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...

  17. Fault diagnosis of air conditioning systems based on qualitative bond graph

    International Nuclear Information System (INIS)

    Ghiaus, C.

    1999-01-01

    The bond graph method represents a unified approach for modeling engineering systems. The main idea is that power transfer bonds the components of a system. The bond graph model is the same for both quantitative representation, in which parameters have numerical values, and qualitative approach, in which they are classified qualitatively. To infer the cause of faults using a qualitative method, a system of qualitative equations must be solved. However, the characteristics of qualitative operators require specific methods for solving systems of equations having qualitative variables. This paper proposes both a method for recursively solving the qualitative system of equations derived from bond graph, and a bond graph model of a direct-expansion, mechanical vapor-compression air conditioning system. Results from diagnosing two faults in a real air conditioning system are presented and discussed. Occasionally, more than one fault candidate is inferred for the same set of qualitative values derived from measurements. In these cases, additional information is required to localize the fault. Fault diagnosis is initiated by a fault detection mechanism which also classifies the quantitative measurements into qualitative values; the fault detection is not presented here. (author)

  18. Irreversible bonding of polyimide and polydimethylsiloxane (PDMS) based on a thiol-epoxy click reaction

    International Nuclear Information System (INIS)

    Hoang, Michelle V; Chung, Hyun-Joong; Elias, Anastasia L

    2016-01-01

    Polyimide is one of the most popular substrate materials for the microfabrication of flexible electronics, while polydimethylsiloxane (PDMS) is the most widely used stretchable substrate/encapsulant material. These two polymers are essential in fabricating devices for microfluidics, bioelectronics, and the internet of things; bonding these materials together is a crucial challenge. In this work, we employ click chemistry at room temperature to irreversibly bond polyimide and PDMS through thiol-epoxy bonds using two different methods. In the first method, we functionalize the surfaces of the PDMS and polyimide substrates with mercaptosilanes and epoxysilanes, respectively, for the formation of a thiol-epoxy bond in the click reaction. In the second method, we functionalize one or both surfaces with mercaptosilane and introduce an epoxy adhesive layer between the two surfaces. When the surfaces are bonded using the epoxy adhesive without any surface functionalization, an extremely small peel strength (<0.01 N mm −1 ) is measured with a peel test, and adhesive failure occurs at the PDMS surface. With surface functionalization, however, remarkably higher peel strengths of ∼0.2 N mm −1 (method 1) and  >0.3 N mm −1 (method 2) are observed, and failure occurs by tearing of the PDMS layer. We envision that the novel processing route employing click chemistry can be utilized in various cases of stretchable and flexible device fabrication. (paper)

  19. A Managerial Perspective on Common Identity-based and Common Bond-based Groups in Non-governmental Organizations. Patterns of Interaction, Attachment and Social Network Configuration

    Directory of Open Access Journals (Sweden)

    Elena - Mădălina VĂTĂMĂNESCU

    2014-10-01

    Full Text Available The paper approaches the common identity and common bond theories in analyzing the group patterns of interaction, their causes, processes and outcomes from a managerial perspective. The distinction between identity and bond referred to people’s different reasons for being in a group, stressing out whether they like the group as a whole — identity-based attachment, or they like individuals in the group — bond-based attachment.  While members of the common identity groups reported feeling more attached to their group as a whole than to their fellow group members and tended to perceive others in the group as interchangeable, in bond-based attachment, people felt connected to each other and less to the group as a whole, loyalty or attraction to the group stemming from their attraction primarily to certain members in the group. At this level, the main question concerned with the particularities of common identity-based or common bond-based groups regarding social interaction, the participatory architecture of the group, the levels of personal and work engagement in acting like a cohesive group. In order to address pertinently this issue, the current work was focused on a qualitative research which comprised in-depth (semi-structured interviews with several project coordinators from non-governmental organizations (NGOs. Also, to make the investigation more complex and clear, the research relied on the social network analysis which was indicative of the group dynamics and configuration, highlighting the differences between common identity-based and common bond-based groups.

  20. Oligomers Based on a Weak Hydrogen Bond Network: the Rotational Spectrum of the Tetramer of Difluoromethane

    Science.gov (United States)

    Feng, Gang; Evangelisti, Luca; Caminati, Walther; Cacelli, Ivo; Carbonaro, Laura; Prampolini, Giacomo

    2013-06-01

    Following the investigation of the rotational spectra of three conformers (so-called ``book'', ``prism'' and ``cage'') of the water hexamer, and of some other water oligomers, we report here the rotational spectrum of the tetramer of a freon molecule. The pulse jet Fourier transform microwave (pj-FTMW) spectrum of an isomer of the difluoromethane tetramer has been assigned. This molecular system is made of units of a relatively heavy asymmetric rotor, held together by a network of weak hydrogen bonds. The search of the rotational spectrum has been based on a high-level reference method, the CCSD(T)/CBS protocol. It is interesting to outline that the rotational spectrum of the water tetramer was not observed, probably because the minimum energy structures of this oligomer is effectively nonpolar in its ground states, or because of high energy tunnelling splittings. The rotational spectra of the monomer, dimer, trimer and tetramer of difluoromethane have been assigned in 1952, 1999, 2007, and 2013 (present work), with a decreasing time spacing between the various steps, looking then promising for a continuous and rapid extension of the size limits of molecular systems accessible to MW spectroscopy. C. Pérez, M. T. Muckle, D. P. Zaleski, N. A. Seifert, B. Temelso, G. C. Shields, Z. Kisiel, B. H. Pate, Science {336} (2012) 897. D. R. Lide, Jr., J. Am. Chem. Soc. {74} (1952) 3548. W. Caminati, S. Melandri, P. Moreschini, P. G. Favero, Angew. Chem. Int. Ed. {38} (1999) 2924. S. Blanco, S. Melandri, P. Ottaviani, W. Caminati, J. Am. Chem. Soc. {129} (2007) 2700.

  1. Iron-phosphate-based chemically bonded phosphate ceramics for mixed waste stabilization

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    In an effort to develop chemically bonded phosphate ceramics for mixed waste stabilization, a collaborative project to develop iron-phosphate based ceramics has been initiated between Argonne National Laboratory and the V. G. Khlopin Radium Institute in St. Petersburg, Russia. The starter powders are oxides of iron that are generated as inexpensive byproduct materials in the iron and steel industry. They contain iron oxides as a mixture of magnetite (Fe 3 O 4 ) and haematite (Fe 2 O 3 ). In this initial phase of this project, both of these compounds were investigated independently. Each was reacted with phosphoric acid solution to form iron phosphate ceramics. In the case of magnetite, the reaction was rapid. Adding ash as the waste component containing hazardous contaminants resulted in a dense and hard ceramic rich in glassy phase. On the other hand, the reaction of phosphoric acid solution with a mixture of haematite and ash waste contaminated with cesium and americium was too slow. Samples had to be molded under pressure. They were cured for 2-3 weeks and then hardened by heating at 350 degrees C for 3 h. The resulting ceramics in both cases were subjected to physical tests for measurement of density, open porosity, compression strength, phase analyses using X-ray diffraction and differential thermal analysis, and leaching tests using toxicity characteristic leaching procedure (TCLP) and ANS 16.1 with 7 days of leaching. Using the preliminary information obtained from these tests, we evaluated these materials for stabilization of Department of Energy's mixed waste streams

  2. Relative Leukocyte Telomere Length, Hematological Parameters and Anemia - Data from the Berlin Aging Study II (BASE-II).

    Science.gov (United States)

    Meyer, Antje; Salewsky, Bastian; Buchmann, Nikolaus; Steinhagen-Thiessen, Elisabeth; Demuth, Ilja

    2016-01-01

    The length of the chromosome ends, telomeres, is widely accepted as a biomarker of aging. However, the dynamic of the relationship between telomere length and hematopoietic parameters in the normal aging process, which is of particular interest with respect to age-related anemia, is not well understood. We have analyzed the relationship between relative leukocyte telomere length (rLTL) and several hematological parameters in the older group of the Berlin Aging Study II (BASE-II) participants. This paper also compares rLTL between both BASE-II age groups (22-37 and 60-83 years). Genomic DNA was extracted from peripheral blood leukocytes of BASE-II participants and used to determine rLTL by a quantitative PCR protocol. Standard methods were used to determine blood parameters, and the WHO criteria were used to identify anemic participants. Telomere length data were available for 444 younger participants (28.4 ± 3.1 years old; 52% women) and 1,460 older participants (68.2 ± 3.7 years old; 49.4% women). rLTL was significantly shorter in BASE-II participants of the older group (p = 3.7 × 10-12) and in women (p = 4.2 × 10-31). rLTL of older men exhibited a statistically significant, positive partial correlation with mean corpuscular hemoglobin (MCH; p = 0.012) and MCH concentration (p = 0.002). While these correlations were only observed in men, the rLTL of older women was negatively correlated with the number of thrombocytes (p = 0.015) in the same type of analysis. Among all older participants, 6% met the criteria to be categorized as 'anemic'; however, there was no association between anemia and rLTL. In the present study, we have detected isolated correlations between rLTL and hematological parameters; however, in all cases, rLTL explained only a small part of the variation of the analyzed parameters. In disagreement with some other studies showing similar data, we interpret the association between rLTL and some of the hematological parameters studied here to be

  3. 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…

  4. Verifiable Outsourced Decryption of Attribute-Based Encryption with Constant Ciphertext Length

    Directory of Open Access Journals (Sweden)

    Jiguo Li

    2017-01-01

    Full Text Available Outsourced decryption ABE system largely reduces the computation cost for users who intend to access the encrypted files stored in cloud. However, the correctness of the transformation ciphertext cannot be guaranteed because the user does not have the original ciphertext. Lai et al. provided an ABE scheme with verifiable outsourced decryption which helps the user to check whether the transformation done by the cloud is correct. In order to improve the computation performance and reduce communication overhead, we propose a new verifiable outsourcing scheme with constant ciphertext length. To be specific, our scheme achieves the following goals. (1 Our scheme is verifiable which ensures that the user efficiently checks whether the transformation is done correctly by the CSP. (2 The size of ciphertext and the number of expensive pairing operations are constant, which do not grow with the complexity of the access structure. (3 The access structure in our scheme is AND gates on multivalued attributes and we prove our scheme is verifiable and it is secure against selectively chosen-plaintext attack in the standard model. (4 We give some performance analysis which indicates that our scheme is adaptable for various limited bandwidth and computation-constrained devices, such as mobile phone.

  5. Halogen bonding from a hard and soft acids and bases perspective: investigation by using density functional theory reactivity indices.

    Science.gov (United States)

    Pinter, Balazs; Nagels, Nick; Herrebout, Wouter A; De Proft, Frank

    2013-01-07

    Halogen bonds between the trifluoromethyl halides CF(3)Cl, CF(3)Br and CF(3)I, and dimethyl ether, dimethyl sulfide, trimethylamine and trimethyl phosphine were investigated using Pearson's hard and soft acids and bases (HSAB) concept with conceptual DFT reactivity indices, the Ziegler-Rauk-type energy-decomposition analysis, the natural orbital for chemical valence (NOCV) framework and the non-covalent interaction (NCI) index. It is found that the relative importance of electrostatic and orbital (charge transfer) interactions varies as a function of both the donor and acceptor molecules. Hard and soft interactions were distinguished and characterised by atomic charges, electrophilicity and local softness indices. Dual-descriptor plots indicate an orbital σ hole on the halogen similar to the electrostatic σ hole manifested in the molecular electrostatic potential. The predicted high halogen-bond-acceptor affinity of N-heterocyclic carbenes was evidenced in the highest complexation energy for the hitherto unknown CF(3) I·NHC complex. The dominant NOCV orbital represents an electron-density deformation according to a n→σ*-type interaction. The characteristic signal found in the reduced density gradient versus electron-density diagram corresponds to the non-covalent interaction between contact atoms in the NCI plots, which is the manifestation of halogen bonding within the NCI theory. The unexpected C-X bond strengthening observed in several cases was rationalised within the molecular orbital framework. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. 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 ...

  7. Improved Road-Network-Flow Control Strategy Based on Macroscopic Fundamental Diagrams and Queuing Length in Connected-Vehicle Network

    Directory of Open Access Journals (Sweden)

    Xiaohui Lin

    2017-01-01

    Full Text Available Connected-vehicles network provides opportunities and conditions for improving traffic signal control, and macroscopic fundamental diagrams (MFD can control the road network at the macrolevel effectively. This paper integrated proposed real-time access to the number of mobile vehicles and the maximum road queuing length in the Connected-vehicles network. Moreover, when implementing a simple control strategy to limit the boundary flow of a road network based on MFD, we determined whether the maximum queuing length of each boundary section exceeds the road-safety queuing length in real-time calculations and timely adjusted the road-network influx rate to avoid the overflow phenomenon in the boundary section. We established a road-network microtraffic simulation model in VISSIM software taking a district as the experimental area, determined MFD of the region based on the number of mobile vehicles, and weighted traffic volume of the road network. When the road network was tending to saturate, we implemented a simple control strategy and our algorithm limits the boundary flow. Finally, we compared the traffic signal control indicators with three strategies: (1 no control strategy, (2 boundary control, and (3 boundary control with limiting queue strategy. The results show that our proposed algorithm is better than the other two.

  8. Impact of the alkyl chain length on binding of imidazolium-based ionic liquids to bovine serum albumin

    Science.gov (United States)

    Zhang, Mengyue; Wang, Ying; Zhang, Hongmei; Cao, Jian; Fei, Zhenghao; Wang, Yanqing

    2018-05-01

    The effects of six imidazolium-based ionic liquids (ILs) with different alkyl chain length ([CnMim]Cl, n = 2, 4, 6, 8, 10, 12) on the structure and functions of bovine serum albumin (BSA) were studied by multi-spectral methods and molecular docking. ILs with the longer alkyl chain length have the stronger binding interaction with BSA and the greater conformational damage to protein. The effects of ILs on the functional properties of BSA were further studied by the determination of non-enzyme esterase activity, β-fibrosis and other properties of BSA. The thermal stability of BSA was reduced, the rate of the formation of beta sheet structures of BSA was lowered, and the esterase-like activity of BSA were decreased with the increase of ILs concentration. Simultaneous molecular modeling technique revealed the favorable binding sites of ILs on protein. The hydrophobic force and polar interactions were the mainly binding forces of them. The calculated results are in a good agreement with the spectroscopic experiments. These studies on the impact of the alkyl chain length on binding of imidazolium-based ionic liquids to BSA are of great significance for understanding and developing the application of ionic liquid in life and physiological system.

  9. Evaluation of bond strength of silorane and methacrylate based restorative systems to dentin using different cavity models

    Directory of Open Access Journals (Sweden)

    Stephano Zerlottini Isaac

    2013-09-01

    Full Text Available OBJECTIVE: The aim of this in vitro study was to evaluate the microtensile bond strength (µTBS to dentin of two different restorative systems: silorane-based (P90, and methacrylate-based (P60, using two cavity models. MATERIAL AND METHODS: Occlusal enamel of 40 human third molars was removed to expose flat dentin surface. Class I cavities with 4 mm mesial-distal width, 3 mm buccal-lingual width and 3 mm depth (C-factor=4.5 were prepared in 20 teeth, which were divided into two groups (n=10 restored with P60 and P90, bulk-filled after dentin treatment according to manufacturer's instructions. Flat buccal dentin surfaces were prepared in the 20 remaining teeth (C-factor=0.2 and restored with resin blocks measuring 4x3x3 mm using the two restorative systems (n=10. The teeth were sectioned into samples with area between 0.85 and 1.25 mm2 that were submitted to µTBS testing, using a universal testing machine (EMIC at speed of 0.5 mm/min. Fractured specimens were analyzed under stereomicroscope and categorized according to fracture pattern. Data were analyzed using ANOVA and Tukey Kramer tests. RESULTS: For flat surfaces, P60 obtained higher bond strength values compared with P90. However, for Class I cavities, P60 showed significant reduction in bond strength (p0.05, or between Class I Cavity and Flat Surface group, considering P90 restorative system (p>0.05. Regarding fracture pattern, there was no statistical difference among groups (p=0.0713 and 56.3% of the fractures were adhesive. CONCLUSION: It was concluded that methacrylate-based composite µTBS was influenced by cavity models, and the use of silorane-based composite led to similar bond strength values compared to the methacrylate-based composite in cavities with high C-factor.

  10. 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.

  11. The development of learning materials based on core model to improve students’ learning outcomes in topic of Chemical Bonding

    Science.gov (United States)

    Avianti, R.; Suyatno; Sugiarto, B.

    2018-04-01

    This study aims to create an appropriate learning material based on CORE (Connecting, Organizing, Reflecting, Extending) model to improve students’ learning achievement in Chemical Bonding Topic. This study used 4-D models as research design and one group pretest-posttest as design of the material treatment. The subject of the study was teaching materials based on CORE model, conducted on 30 students of Science class grade 10. The collecting data process involved some techniques such as validation, observation, test, and questionnaire. The findings were that: (1) all the contents were valid, (2) the practicality and the effectiveness of all the contents were good. The conclusion of this research was that the CORE model is appropriate to improve students’ learning outcomes for studying Chemical Bonding.

  12. Parental bonding and suicidality in pregnant teenagers: a population-based study in southern Brazil.

    Science.gov (United States)

    Coelho, Fábio Monteiro da Cunha; Pinheiro, Ricardo Tavares; Silva, Ricardo Azevedo; de Ávila Quevedo, Luciana; de Mattos Souza, Luciano Dias; de Matos, Mariana Bonati; Castelli, Rochele Dias; Pinheiro, Karen Amaral Tavares

    2014-08-01

    To assess the associations of the perceived quality of parental bonding with suicidality in a sample of pregnant adolescents. A cross-sectional study with a sample size of 828 pregnant teenagers receiving prenatal medical assistance in the national public health system in the urban area of Pelotas, southern Brazil. Suicidality and psychiatric disorders were assessed using the Mini International Neuropsychiatric Interview (MINI), and the Parental Bonding Instrument (PBI) was employed to measure the perceived quality of parental bonding. A self-report questionnaire was used to collect sociodemographic, obstetric and other psychosocial data. Forty-three (4.94 %) teenagers from a consecutive sample of 871 refused to participate, resulting in 828 participants. Prevalence of suicidality was 13.3 %, lifetime suicide attempts were 7.4 % with 1.3 % reporting attempting suicide within the last month. Significant associations of suicidality with the 18-19-year-old subgroup, low education, prior abortion, physical abuse within the last 12 months were present, and most psychiatric disorders were associated with a higher suicidality prevalence. Additionally, after adjustment in the multivariate analysis, the style of parental bonding was independently associated with suicidality in the pregnant adolescent, with a PR of 2.53 (95 % CI 1.14-5.59) for the maternal 'affectionless control' and a PR of 2.91 (95 % CI 1.10-7.70) for the paternal 'neglectful parenting.' We found that maternal 'affectionless control' and paternal 'neglectful parenting' were independent predictors of suicidality in this sample of pregnant teenagers.

  13. A study of the impact properties of adhesively-bonded aluminum alloy based on impact velocity

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Teng; Cheon, Seong Sik; Cho, Jae Ung [Kongju National University, Cheonan (Korea, Republic of); Kinloch, Anthony J.; Blackman, Bamber R. K.; Sanchez, F. S. Rodriguez [Imperial College London, London (United Kingdom); Bang, Hye Jin; Lee, Sang Kyo; Cho, Chong Du [Inha University, Seoul (Korea, Republic of)

    2015-02-15

    In this study, an experiment and a simulation were carried out on colliding an adhesively-bonded tapered double cantilever beam (TDCB) at the impact velocities of 5 m/s, 7.5 m/s and 12.5 m/s. The analysis method of the corrected beam theory (CBT) was used to obtain the rate of energy release in the bonded area according to the crack progression, and a simulation was performed to determine the maximum strain energy during the impact analysis as a means to examine the mechanical properties of aluminium alloy. The experimental data were found to be higher than the simulation data. This is deemed to explicable by the fact that the adhesive strength was maintained even after the specimen separated in the experiment. Crack progression occurred, irrespective of the impact velocity, and high strain energy occurred at the end of the bonded region, thereby causing the strain energy to increase in the final stages. Also, the maximum load applied on the pin and the maximum strain energy in the bonded area were shown increase at higher impact velocities. The results of the experiment and simulation performed in this study are expected to serve as important data in developing a safety design for composite materials that can help prevent the progression of cracks caused by impact.

  14. H-shaped supra-amphiphiles based on a dynamic covalent bond.

    Science.gov (United States)

    Wang, Guangtong; Wang, Chao; Wang, Zhiqiang; Zhang, Xi

    2012-10-16

    The imine bond, a kind of dynamic covalent bond, is used to bind two bolaform amphiphiles together with spacers, yielding H-shaped supra-amphiphiles. Micellar aggregates formed by the self-assembly of the H-shaped supra-amphiphiles are observed. When pH is tuned down from basic to slightly acidic, the benzoic imine bond can be hydrolyzed, leading to the dissociation of H-shaped supra-amphiphiles. Moreover, H-shaped supra-amphiphiles have a lower critical micelle concentration than their building blocks, which is very helpful in enhancing the stability of the benzoic imine bond being hydrolyzed by acid. The surface tension isotherms of the H-shaped supra-amphiphiles with different spacers indicate their twisty conformation at a gas-water interface. The study of H-shaped supra-amphiphiles can enrich the family of amphiphiles, and moreover, the pH-responsiveness may make them apply to controlled or targetable drug delivery in a biological environment.

  15. Bond-based linear indices in QSAR: computational discovery of novel anti-trichomonal compounds

    Science.gov (United States)

    Marrero-Ponce, Yovani; Meneses-Marcel, Alfredo; Rivera-Borroto, Oscar M.; García-Domenech, Ramón; De Julián-Ortiz, Jesus Vicente; Montero, Alina; Escario, José Antonio; Barrio, Alicia Gómez; Pereira, David Montero; Nogal, Juan José; Grau, Ricardo; Torrens, Francisco; Vogel, Christian; Arán, Vicente J.

    2008-08-01

    Trichomonas vaginalis ( Tv) is the causative agent of the most common, non-viral, sexually transmitted disease in women and men worldwide. Since 1959, metronidazole (MTZ) has been the drug of choice in the systemic treatment of trichomoniasis. However, resistance to MTZ in some patients and the great cost associated with the development of new trichomonacidals make necessary the development of computational methods that shorten the drug discovery pipeline. Toward this end, bond-based linear indices, new TOMOCOMD-CARDD molecular descriptors, and linear discriminant analysis were used to discover novel trichomonacidal chemicals. The obtained models, using non-stochastic and stochastic indices, are able to classify correctly 89.01% (87.50%) and 82.42% (84.38%) of the chemicals in the training (test) sets, respectively. These results validate the models for their use in the ligand-based virtual screening. In addition, they show large Matthews' correlation coefficients ( C) of 0.78 (0.71) and 0.65 (0.65) for the training (test) sets, correspondingly. The result of predictions on the 10% full-out cross-validation test also evidences the robustness of the obtained models. Later, both models are applied to the virtual screening of 12 compounds already proved against Tv. As a result, they correctly classify 10 out of 12 (83.33%) and 9 out of 12 (75.00%) of the chemicals, respectively; which is the most important criterion for validating the models. Besides, these classification functions are applied to a library of seven chemicals in order to find novel antitrichomonal agents. These compounds are synthesized and tested for in vitro activity against Tv. As a result, experimental observations approached to theoretical predictions, since it was obtained a correct classification of 85.71% (6 out of 7) of the chemicals. Moreover, out of the seven compounds that are screened, synthesized and biologically assayed, six compounds (VA7-34, VA7-35, VA7-37, VA7-38, VA7-68, VA7-70) show

  16. Pricing index-based catastrophe bonds: Part 1: Formulation and discretization issues using a numerical PDE approach

    Science.gov (United States)

    Unger, André J. A.

    2010-02-01

    This work is the first installment in a two-part series, and focuses on the development of a numerical PDE approach to price components of a Bermudan-style callable catastrophe (CAT) bond. The bond is based on two underlying stochastic variables; the PCS index which posts quarterly estimates of industry-wide hurricane losses as well as a single-factor CIR interest rate model for the three-month LIBOR. The aggregate PCS index is analogous to losses claimed under traditional reinsurance in that it is used to specify a reinsurance layer. The proposed CAT bond model contains a Bermudan-style call feature designed to allow the reinsurer to minimize their interest rate risk exposure on making substantial fixed coupon payments using capital from the reinsurance premium. Numerical PDE methods are the fundamental strategy for pricing early-exercise constraints, such as the Bermudan-style call feature, into contingent claim models. Therefore, the objective and unique contribution of this first installment in the two-part series is to develop a formulation and discretization strategy for the proposed CAT bond model utilizing a numerical PDE approach. Object-oriented code design is fundamental to the numerical methods used to aggregate the PCS index, and implement the call feature. Therefore, object-oriented design issues that relate specifically to the development of a numerical PDE approach for the component of the proposed CAT bond model that depends on the PCS index and LIBOR are described here. Formulation, numerical methods and code design issues that relate to aggregating the PCS index and introducing the call option are the subject of the companion paper.

  17. A method for estimating age of medieval sub-adults from infancy to adulthood based on long bone length

    DEFF Research Database (Denmark)

    Primeau, Charlotte; Friis, Laila Saidane; Sejrsen, Birgitte

    2016-01-01

    OBJECTIVES: To develop a series of regression equations for estimating age from length of long bones for archaeological sub-adults when aging from dental development cannot be performed. Further, to compare derived ages when using these regression equations, and two other methods. MATERIAL AND ME...... as later than the medieval period, although this would require further testing. The quadratic equations are suggested to yield more accurate ages then using simply linear regression equations. Am J Phys Anthropol, 2015. © 2015 Wiley Periodicals, Inc.......OBJECTIVES: To develop a series of regression equations for estimating age from length of long bones for archaeological sub-adults when aging from dental development cannot be performed. Further, to compare derived ages when using these regression equations, and two other methods. MATERIAL...... AND METHODS: A total of 183 skeletal sub-adults from the Danish medieval period, were aged from radiographic images. Linear regression formulae were then produced for individual bones. Age was then estimated from the femur length using three different methods: equations developed in this study, data based...

  18. 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.)

  19. Effects of Personalization and Invitation Email Length on Web-Based Survey Response Rates

    Science.gov (United States)

    Trespalacios, Jesús H.; Perkins, Ross A.

    2016-01-01

    Individual strategies to increase response rate and survey completion have been extensively researched. Recently, efforts have been made to investigate a combination of interventions to yield better response rates for web-based surveys. This study examined the effects of four different survey invitation conditions on response rate. From a large…

  20. Size effects in tin-based lead-free solder joints: Kinetics of bond formation and mechanical characteristics

    Science.gov (United States)

    Abdelhadi, Ousama Mohamed Omer

    Continuous miniaturization of microelectronic interconnects demands smaller joints with comparable microstructural and structural sizes. As the size of joints become smaller, the volume of intermetallics (IMCs) becomes comparable with the joint size. As a result, the kinetics of bond formation changes and the types and thicknesses of IMC phases that form within the constrained region of the bond varies. This dissertation focuses on investigating combination effects of process parameters and size on kinetics of bond formation, resulting microstructure and the mechanical properties of joints that are formed under structurally constrained conditions. An experiment is designed where several process parameters such as time of bonding, temperature, and pressure, and bond thickness as structural chracteristic, are varied at multiple levels. The experiment is then implemented on the process. Scanning electron microscope (SEM) is then utilized to determine the bond thickness, IMC phases and their thicknesses, and morphology of the bonds. Electron backscatter diffraction (EBSD) is used to determine the grain size in different regions, including the bulk solder, and different IMC phases. Physics-based analytical models have been developed for growth kinetics of IMC compounds and are verified using the experimental results. Nanoindentation is used to determine the mechanical behavior of IMC phases in joints in different scales. Four-point bending notched multilayer specimen and four-point bending technique were used to determine fracture toughness of the bonds containing IMCs. Analytical modeling of peeling and shear stresses and fracture toughness in tri-layer four-point bend specimen containing intermetallic layer was developed and was verified and validated using finite element simulation and experimental results. The experiment is used in conjunction with the model to calculate and verify the fracture toughness of Cu6Sn5 IMC materials. As expected two different IMC phases

  1. An unbiased stereological method for efficiently quantifying the innervation of the heart and other organs based on total length estimations

    DEFF Research Database (Denmark)

    Mühlfeld, Christian; Papadakis, Tamara; Krasteva, Gabriela

    2010-01-01

    Quantitative information about the innervation is essential to analyze the structure-function relationships of organs. So far, there has been no unbiased stereological tool for this purpose. This study presents a new unbiased and efficient method to quantify the total length of axons in a given...... reference volume, illustrated on the left ventricle of the mouse heart. The method is based on the following steps: 1) estimation of the reference volume; 2) randomization of location and orientation using appropriate sampling techniques; 3) counting of nerve fiber profiles hit by a defined test area within...

  2. An Efficient Key-Policy Attribute-Based Encryption Scheme with Constant Ciphertext Length

    Directory of Open Access Journals (Sweden)

    Changji Wang

    2013-01-01

    Full Text Available There is an acceleration of adoption of cloud computing among enterprises. However, moving the infrastructure and sensitive data from trusted domain of the data owner to public cloud will pose severe security and privacy risks. Attribute-based encryption (ABE is a new cryptographic primitive which provides a promising tool for addressing the problem of secure and fine-grained data sharing and decentralized access control. Key-policy attribute-based encryption (KP-ABE is an important type of ABE, which enables senders to encrypt messages under a set of attributes and private keys are associated with access structures that specify which ciphertexts the key holder will be allowed to decrypt. In most existing KP-ABE scheme, the ciphertext size grows linearly with the number of attributes embedded in ciphertext. In this paper, we propose a new KP-ABE construction with constant ciphertext size. In our construction, the access policy can be expressed as any monotone access structure. Meanwhile, the ciphertext size is independent of the number of ciphertext attributes, and the number of bilinear pairing evaluations is reduced to a constant. We prove that our scheme is semantically secure in the selective-set model based on the general Diffie-Hellman exponent assumption.

  3. Characterization of the Bonds Developed between Calcium Silicate Hydrate and Polycarboxylate-Based Superplasticizers with Silyl Functionalities.

    Science.gov (United States)

    Orozco, Carlos A; Chun, Byong W; Geng, Guoqing; Emwas, Abdul H; Monteiro, Paulo J M

    2017-04-11

    Major developments in concrete technology have been achieved with the use of polycarboxylate-based superplasticizers (PCEs) to improve the concrete rheology without increasing the mix water content. Currently, it is possible to control the fluidity of the fresh concrete and obtain stronger and more durable structures. Therefore, there is a strong incentive to understand the interactions between PCEs and cement hydrates at the atomic scale to design new customized functional PCEs according to the ever-increasing requirements of the concrete industry. Here, the bonding types generated between a PCE with silyl functionalities (PCE-Sil) and a synthetic calcium silicate hydrate (C-S-H) are analyzed using XRD, 29 Si NMR spectroscopy, and synchrotron-based techniques, such as NEXAFS and EXAFS. The results indicated that the carboxylic groups present in PCE-Sil interact by a ligand-type bond with calcium, which modified not only the symmetry and coordination number of the calcium located at the surface of C-S-H but also the neighboring silicon atoms of the C-S-H. In addition, the silyl functionalities of the PCE-Sil generated covalent bonds through siloxane bridges between the silanol groups of PCE-Sil and the nonbonding oxygen located at the dimeric sites in C-S-H, forming new bridging silicon sites and subsequently increasing the silicate polymerization.

  4. Characterization of the Bonds Developed between Calcium Silicate Hydrate and Polycarboxylate-Based Superplasticizers with Silyl Functionalities

    KAUST Repository

    Orozco, Carlos A.; Chun, Byong W.; Geng, Guoqing; Emwas, Abdul-Hamid M.; Monteiro, Paulo J. M.

    2017-01-01

    Major developments in concrete technology have been achieved with the use of polycarboxylate-based superplasticizers (PCEs) to improve the concrete rheology without increasing the mix water content. Currently, it is possible to control the fluidity of the fresh concrete and obtain stronger and more durable structures. Therefore, there is a strong incentive to understand the interactions between PCEs and cement hydrates at the atomic scale to design new customized functional PCEs according to the ever-increasing requirements of the concrete industry. Here, the bonding types generated between a PCE with silyl functionalities (PCE-Sil) and a synthetic calcium silicate hydrate (C-S-H) are analyzed using XRD, 29Si NMR spectroscopy, and synchrotron-based techniques, such as NEXAFS and EXAFS. The results indicated that the carboxylic groups present in PCE-Sil interact by a ligand-type bond with calcium, which modified not only the symmetry and coordination number of the calcium located at the surface of C-S-H but also the neighboring silicon atoms of the C-S-H. In addition, the silyl functionalities of the PCE-Sil generated covalent bonds through siloxane bridges between the silanol groups of PCE-Sil and the nonbonding oxygen located at the dimeric sites in C-S-H, forming new bridging silicon sites and subsequently increasing the silicate polymerization.

  5. Characterization of the Bonds Developed between Calcium Silicate Hydrate and Polycarboxylate-Based Superplasticizers with Silyl Functionalities

    KAUST Repository

    Orozco, Carlos A.

    2017-03-24

    Major developments in concrete technology have been achieved with the use of polycarboxylate-based superplasticizers (PCEs) to improve the concrete rheology without increasing the mix water content. Currently, it is possible to control the fluidity of the fresh concrete and obtain stronger and more durable structures. Therefore, there is a strong incentive to understand the interactions between PCEs and cement hydrates at the atomic scale to design new customized functional PCEs according to the ever-increasing requirements of the concrete industry. Here, the bonding types generated between a PCE with silyl functionalities (PCE-Sil) and a synthetic calcium silicate hydrate (C-S-H) are analyzed using XRD, 29Si NMR spectroscopy, and synchrotron-based techniques, such as NEXAFS and EXAFS. The results indicated that the carboxylic groups present in PCE-Sil interact by a ligand-type bond with calcium, which modified not only the symmetry and coordination number of the calcium located at the surface of C-S-H but also the neighboring silicon atoms of the C-S-H. In addition, the silyl functionalities of the PCE-Sil generated covalent bonds through siloxane bridges between the silanol groups of PCE-Sil and the nonbonding oxygen located at the dimeric sites in C-S-H, forming new bridging silicon sites and subsequently increasing the silicate polymerization.

  6. Novel alternating polymer adsorption/surface activation self-assembled film based on hydrogen bond

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yongjun; Yang Shuguang; Guan Ying; Miao Xiaopeng; Cao Weixiao; Xu Jian

    2003-08-01

    By combining hydrogen bonding layer-by-layer self-assembly and the stepwise chemisorption method, a new alternating polymer adsorption/surface activation self-assembly method was developed. First a layer of diphenylamine-4-diazonium-formaldehyde resin (diazo resin or DR) is deposited on a substrate. In the following surface activation step, the diazonium groups on the surface couple with resorcin in the outside solution. The deposition of another layer of DR is feasible due to the formation of hydrogen bond between the diazonium group of DR and the hydroxy group of the resorcin moieties. The resulting film is photosensitive. After UV irradiation, the film becomes very stable towards polar organic solvents.

  7. Selective bond cleavage in potassium collisions with pyrimidine bases of DNA.

    Science.gov (United States)

    Almeida, Diogo; Ferreira da Silva, Filipe; García, Gustavo; Limão-Vieira, Paulo

    2013-01-11

    Electron transfer in alkali-molecule collisions to gas phase thymine and uracil yielding H- formation is selectively controlled in the energy range between 5.3 and 66.1 eV. By tuning the collision energy, electron transfer from the alkali to partly deuterated thymine, methylated thymine at the N1 and methylated uracil at the N3 positions, H- loss proceeds not only through the breaking of the (C-H) against (N-H) bonds but also through N1 against N3 sites. Such selectivity, as far as bond and site are concerned, is here reported for the first time by electron transfer induced dissociation experiments in alkali-molecule collisions.

  8. Analysis of the physical properties of trehalose-water-lithium iodide based on the bond strength coordination number fluctuation model

    International Nuclear Information System (INIS)

    Sahara; Jean L Ndeugueu; Masaru Aniya

    2010-01-01

    The temperature dependence of the viscosity of trehalose-water-lithium iodide system has been investigated by the mean of the Bond Strength Coordination Number Fluctuation (BSCNF) model. The result indicates that by increasing the trehalose content, maintaining the content of LiI constant, the fragility decreases due to the increase of the connectivity between the structural units. Our analysis suggests also that the fragility of the system is controlled by the amount of water in the composition. By increasing the water content, the total bond strength decreases and its fluctuation increases, resulting in the increase of the fragility. Based on the analysis of the obtained parameters of the BSCNF model, a physical interpretation of the VFT parameters reported in a previous study has been given. (author)

  9. Stable Au-C bonds to the substrate for fullerene-based nanostructures

    Czech Academy of Sciences Publication Activity Database

    Chutora, Taras; López, Roso Redondo Jesús R.; De La Torre Cerdeño, Bruno; Švec, Martin; Jelínek, Pavel; Vázquez, Héctor

    2017-01-01

    Roč. 8, č. 1 (2017), s. 1073-1079 ISSN 2190-4286 R&D Projects: GA ČR GA15-19672S Institutional support: RVO:68378271 Keywords : Au-C bonds * density functional theory (DFT) * fullerenes * scanning tunneling microscopy (STM) * sputtering Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.127, year: 2016

  10. DNA base dimers are stabilized by hydrogen-bonding interactions including non-Watson-Crick pairing near graphite surfaces.

    Science.gov (United States)

    Shankar, Akshaya; Jagota, Anand; Mittal, Jeetain

    2012-10-11

    Single- and double-stranded DNA are increasingly being paired with surfaces and nanoparticles for numerous applications, such as sensing, imaging, and drug delivery. Unlike the majority of DNA structures in bulk that are stabilized by canonical Watson-Crick pairing between Ade-Thy and Gua-Cyt, those adsorbed on surfaces are often stabilized by noncanonical base pairing, quartet formation, and base-surface stacking. Not much is known about these kinds of interactions. To build an understanding of the role of non-Watson-Crick pairing on DNA behavior near surfaces, one requires basic information on DNA base pair stacking and hydrogen-bonding interactions. All-atom molecular simulations of DNA bases in two cases--in bulk water and strongly adsorbed on a graphite surface--are conducted to study the relative strengths of stacking and hydrogen bond interactions for each of the 10 possible combinations of base pairs. The key information obtained from these simulations is the free energy as a function of distance between two bases in a pair. We find that stacking interactions exert the dominant influence on the stability of DNA base pairs in bulk water as expected. The strength of stability for these stacking interactions is found to decrease in the order Gua-Gua > Ade-Gua > Ade-Ade > Gua-Thy > Gua-Cyt > Ade-Thy > Ade-Cyt > Thy-Thy > Cyt-Thy > Cyt-Cyt. On the other hand, mutual interactions of surface-adsorbed base pairs are stabilized mostly by hydrogen-bonding interactions in the order Gua-Cyt > Ade-Gua > Ade-Thy > Ade-Ade > Cyt-Thy > Gua-Gua > Cyt-Cyt > Ade-Cyt > Thy-Thy > Gua-Thy. Interestingly, several non-Watson-Crick base pairings, which are commonly ignored, have similar stabilization free energies due to interbase hydrogen bonding as Watson-Crick pairs. This clearly highlights the importance of non-Watson-Crick base pairing in the development of secondary structures of oligonucleotides near surfaces.

  11. Relationships for the impact sensitivities of energetic C-nitro compounds based on bond dissociation energy.

    Science.gov (United States)

    Li, Jinshan

    2010-02-18

    The ZPE-corrected C-NO(2) bond dissociation energies (BDEs(ZPE)) of a series of model C-nitro compounds and 26 energetic C-nitro compounds have been calculated using density functional theory methods. Computed results show that for C-nitro compounds the UB3LYP calculated BDE(ZPE) is less than the UB3P86 using the 6-31G** basis set, and the UB3P86 BDE(ZPE) changes slightly with the basis set varying from 6-31G** to 6-31++G**. For the series of model C-nitro compounds with different chemical skeletons, it is drawn from NBO analysis that the order of BDE(ZPE) is not only in line with that of the NAO bond order but also with that of the energy gap between C-NO(2) bonding and antibonding orbitals. It is found that for the energetic C-nitro compounds whose drop energies (Es(dr)) are below 24.5 J a good linear correlation exists between E(dr) and BDE(ZPE), implying that these compounds ignite through the C-NO(2) dissociation mechanism. After excluding the so-called trinitrotoluene mechanism compounds, a polynomial correlation of ln(E(dr)) with the BDE(ZPE) calculated at density functional theory levels has been established successfully for the 18 C-NO(2) dissociation energetic C-nitro compounds.

  12. In situ metalation of free base phthalocyanine covalently bonded to silicon surfaces

    Directory of Open Access Journals (Sweden)

    Fabio Lupo

    2014-11-01

    Full Text Available Free 4-undecenoxyphthalocyanine molecules were covalently bonded to Si(100 and porous silicon through thermic hydrosilylation of the terminal double bonds of the undecenyl chains. The success of the anchoring strategy on both surfaces was demonstrated by the combination of X-ray photoelectron spectroscopy with control experiments performed adopting the commercially available 2,3,9,10,16,17,23,24-octakis(octyloxy-29H,31H-phthalocyanine, which is not suited for silicon anchoring. Moreover, the study of the shape of the XPS N 1s band gave relevant information on the interactions occurring between the anchored molecules and the substrates. The spectra suggest that the phthalocyanine ring interacts significantly with the flat Si surface, whilst ring–surface interactions are less relevant on porous Si. The surface-bonded molecules were then metalated in situ with Co by using wet chemistry. The efficiency of the metalation process was evaluated by XPS measurements and, in particular, on porous silicon, the complexation of cobalt was confirmed by the disappearance in the FTIR spectra of the band at 3290 cm−1 due to –NH stretches. Finally, XPS results revealed that the different surface–phthalocyanine interactions observed for flat and porous substrates affect the efficiency of the in situ metalation process.

  13. Mapping Optimal Charge Density and Length of ROMP-Based PTDMs for siRNA Internalization.

    Science.gov (United States)

    Caffrey, Leah M; deRonde, Brittany M; Minter, Lisa M; Tew, Gregory N

    2016-10-10

    A fundamental understanding of how polymer structure impacts internalization and delivery of biologically relevant cargoes, particularly small interfering ribonucleic acid (siRNA), is of critical importance to the successful design of improved delivery reagents. Herein we report the use of ring-opening metathesis polymerization (ROMP) methods to synthesize two series of guanidinium-rich protein transduction domain mimics (PTDMs): one based on an imide scaffold that contains one guanidinium moiety per repeat unit, and another based on a diester scaffold that contains two guanidinium moieties per repeat unit. By varying both the degree of polymerization and, in effect, the relative number of cationic charges in each PTDM, the performances of the two ROMP backbones for siRNA internalization were evaluated and compared. Internalization of fluorescently labeled siRNA into Jurkat T cells demonstrated that fluorescein isothiocyanate (FITC)-siRNA internalization had a charge content dependence, with PTDMs containing approximately 40 to 60 cationic charges facilitating the most internalization. Despite this charge content dependence, the imide scaffold yielded much lower viabilities in Jurkat T cells than the corresponding diester PTDMs with similar numbers of cationic charges, suggesting that the diester scaffold is preferred for siRNA internalization and delivery applications. These developments will not only improve our understanding of the structural factors necessary for optimal siRNA internalization, but will also guide the future development of optimized PTDMs for siRNA internalization and delivery.

  14. 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.

  15. 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.

  16. Formation of base triplets by non-Watson-Crick bonds mediates homologous recognition in RecA recombination filaments.

    OpenAIRE

    Rao, B J; Radding, C M

    1994-01-01

    Whereas complementary strands of DNA recognize one another by forming Watson-Crick base pairs, the way in which RecA protein enables a single strand to recognize homology in duplex DNA has remained unknown. Recent experiments, however, have shown that a single plus strand in the RecA filament can recognize an identical plus strand via bonds that, by definition, are non-Watson-Crick. In experiments reported here, base substitutions had the same qualitative and quantitative effects on the pairi...

  17. Evaluation on the detection limit of blood hemoglobin using photolepthysmography based on path-length optimization

    Science.gov (United States)

    Sun, Di; Guo, Chao; Zhang, Ziyang; Han, Tongshuai; Liu, Jin

    2016-10-01

    The blood hemoglobin concentration's (BHC) measurement using Photoplethysmography (PPG), which gets blood absorption to near infrared light from the instantaneous pulse of transmitted light intensity, has not been applied to the clinical use due to the non-enough precision. The main challenge might be caused of the non-enough stable pulse signal when it's very weak and it often varies in different human bodies or in the same body with different physiological states. We evaluated the detection limit of BHC using PPG as the measurement precision level, which can be considered as a best precision result because we got the relative stable subject's pulse signals recorded by using a spectrometer with high signal-to-noise ratio (SNR) level, which is about 30000:1 in short term. Moreover, we optimized the used pathlength using the theory based on optimum pathlength to get a better sensitivity to the absorption variation in blood. The best detection limit was evaluated as about 1 g/L for BHC, and the best SNR of pulse for in vivo measurement was about 2000:1 at 1130 and 1250 nm. Meanwhile, we conclude that the SNR of pulse signal should be better than 400:1 when the required detection limit is set to 5 g/L. Our result would be a good reference to the BHC measurement to get a desired BHC measurement precision of real application.

  18. Suppression of interfacial voids formation during silane (SiH4)-based silicon oxide bonding with a thin silicon nitride capping layer

    Science.gov (United States)

    Lee, Kwang Hong; Bao, Shuyu; Wang, Yue; Fitzgerald, Eugene A.; Seng Tan, Chuan

    2018-01-01

    The material properties and bonding behavior of silane-based silicon oxide layers deposited by plasma-enhanced chemical vapor deposition were investigated. Fourier transform infrared spectroscopy was employed to determine the chemical composition of the silicon oxide films. The incorporation of hydroxyl (-OH) groups and moisture absorption demonstrates a strong correlation with the storage duration for both as-deposited and annealed silicon oxide films. It is observed that moisture absorption is prevalent in the silane-based silicon oxide film due to its porous nature. The incorporation of -OH groups and moisture absorption in the silicon oxide films increase with the storage time (even in clean-room environments) for both as-deposited and annealed silicon oxide films. Due to silanol condensation and silicon oxidation reactions that take place at the bonding interface and in the bulk silicon, hydrogen (a byproduct of these reactions) is released and diffused towards the bonding interface. The trapped hydrogen forms voids over time. Additionally, the absorbed moisture could evaporate during the post-bond annealing of the bonded wafer pair. As a consequence, defects, such as voids, form at the bonding interface. To address the problem, a thin silicon nitride capping film was deposited on the silicon oxide layer before bonding to serve as a diffusion barrier to prevent moisture absorption and incorporation of -OH groups from the ambient. This process results in defect-free bonded wafers.

  19. The effect of shape, length and diameter of implants on primary stability based on resonance frequency analysis

    Directory of Open Access Journals (Sweden)

    Hamidreza Barikani

    2014-01-01

    Full Text Available Background: The aim of this in vitro study was to evaluate the effect of shape, diameter and length of implants on their primary stability based on resonance frequency analysis. Materials and Methods: Replace select tapered and Branemark MK III implants were selected. Each of these two selected groups was divided into nine subgroups based on the implant length (IL (short, medium and long and the implant diameter (ID (narrow platform [NP], regular platform [RP] and wide platform [WP]. Five implants were assigned to each of the nine subgroups. Implants were placed in artificial bone blocks with bone quality similar to D3 bone. Immediately after the implant placement, its primary stability was measured using Osstell Mentor equipment. T-test and Tukey′s honest significant difference Post hoc were performed for data analysis. Statistical significance was defined at P < 0.05. Results: Replace select system showed significantly higher primary stability compared to the Branemark system, when using the short implants for all three diameters (P ≤ 0.004. However, in medium length implants there were no significant differences between the two implant systems (P ≥ 0.31. In long implants, only when the NP and RP implants were used, the Replace Select system showed significantly higher primary stability compared to the Branemark system (P = 0.000. In the replace select system, long implants had a significantly higher primary stability compared to medium and short length implants (P ≤ 0.003. In the NP and RP Branemark implants, short implants showed significantly lower primary stability compared to medium and long implants (P ≤ 0.002. However, in WP Branemark implants, primary stability increased significantly with increasing the IL from short to medium and from medium to long (P = 0.000. There were also significant differences between NP and the two other wider implants in both systems (P = 0.000. Conclusion: The use of tapered implants is

  20. A multivariate relationship for the impact sensitivities of energetic N-nitrocompounds based on bond dissociation energy.

    Science.gov (United States)

    Li, Jinshan

    2010-02-15

    The ZPE-corrected N-NO(2) bond dissociation energies (BDEs(ZPE)) of a series of model N-nitrocompounds and typical energetic N-nitrocompounds have been calculated using density functional theory methods. Computed results show that using the 6-31G** basis set the UB3LYP calculated BDE(ZPE) is similar to the B3PW91 but is less than the UB3P86 and that for both UB3P86 and UB3PW91 methods the 6-31G(**) calculated BDE(ZPE) is close to the 6-31++G(**). For the series of model N-nitrocompounds it is drawn from the NBO analysis that at the UB3LYP/6-31G(**) level the order of BDE(ZPE) is not only in line with that of bond order but also with that of the energy gap between N-NO(2) bond and antibond orbitals. For the typical energetic N-nitrocompounds the impact sensitivity is strongly related to the BDE(ZPE) indeed, and based on the BDEs(ZPE) calculated at different density functional theory levels this work has established a good multivariate correlation of impact sensitivity with molecular parameters, which provides a method to address the sensitivity problem.

  1. Influence of increment thickness on dentin bond strength and light transmission of composite base materials.

    Science.gov (United States)

    Omran, Tarek A; Garoushi, Sufyan; Abdulmajeed, Aous A; Lassila, Lippo V; Vallittu, Pekka K

    2017-06-01

    Bulk-fill resin composites (BFCs) are gaining popularity in restorative dentistry due to the reduced chair time and ease of application. This study aimed to evaluate the influence of increment thickness on dentin bond strength and light transmission of different BFCs and a new discontinuous fiber-reinforced composite. One hundred eighty extracted sound human molars were prepared for a shear bond strength (SBS) test. The teeth were divided into four groups (n = 45) according to the resin composite used: regular particulate filler resin composite: (1) G-ænial Anterior [GA] (control); bulk-fill resin composites: (2) Tetric EvoCeram Bulk Fill [TEBF] and (3) SDR; and discontinuous fiber-reinforced composite: (4) everX Posterior [EXP]. Each group was subdivided according to increment thickness (2, 4, and 6 mm). The irradiance power through the material of all groups/subgroups was quantified (MARC® Resin Calibrator; BlueLight Analytics Inc.). Data were analyzed using two-way ANOVA followed by Tukey's post hoc test. SBS and light irradiance decreased as the increment's height increased (p composite used. EXP presented the highest SBS in 2- and 4-mm-thick increments when compared to other composites, although the differences were not statistically significant (p > 0.05). Light irradiance mean values arranged in descending order were (p composites. Discontinuous fiber-reinforced composite showed the highest value of curing light transmission, which was also seen in improved bonding strength to the underlying dentin surface. Discontinuous fiber-reinforced composite can be applied safely in bulks of 4-mm increments same as other bulk-fill composites, although, in 2-mm thickness, the investigated composites showed better performance.

  2. High-fidelity in vivo replication of DNA base shape mimics without Watson–Crick hydrogen bonds

    Science.gov (United States)

    Delaney, James C.; Henderson, Paul T.; Helquist, Sandra A.; Morales, Juan C.; Essigmann, John M.; Kool, Eric T.

    2003-01-01

    We report studies testing the importance of Watson–Crick hydrogen bonding, base-pair geometry, and steric effects during DNA replication in living bacterial cells. Nonpolar DNA base shape mimics of thymine and adenine (abbreviated F and Q, respectively) were introduced into Escherichia coli by insertion into a phage genome followed by transfection of the vector into bacteria. Genetic assays showed that these two base mimics were bypassed with moderate to high efficiency in the cells and with very high efficiency under damage-response (SOS induction) conditions. Under both sets of conditions, the T-shape mimic (F) encoded genetic information in the bacteria as if it were thymine, directing incorporation of adenine opposite it with high fidelity. Similarly, the A mimic (Q) directed incorporation of thymine opposite itself with high fidelity. The data establish that Watson–Crick hydrogen bonding is not necessary for high-fidelity replication of a base pair in vivo. The results suggest that recognition of DNA base shape alone serves as the most powerful determinant of fidelity during transfer of genetic information in a living organism. PMID:12676985

  3. Lengths of the maxillary central incisor, the nasal bone, and the anterior cranial base in different skeletal malocclusions

    DEFF Research Database (Denmark)

    Arntsen, Torill; Kjær, Inger; Sonnesen, Liselotte

    2009-01-01

    with neutral occlusion and normal craniofacial morphology (n=39). Two-way ANOVA tests were used to evaluate differences in lengths between groups and gender. Results. Statistically shorter maxillary central incisor length was found in the open bite group (p

  4. PEGylation of Phytantriol-Based Lyotropic Liquid Crystalline Particles-The Effect of Lipid Composition, PEG Chain Length, and Temperature on the Internal Nanostructure

    DEFF Research Database (Denmark)

    Nilsson, Christa; Ostergaard, Jesper; Larsen, Susan Weng

    2014-01-01

    of these lipidic nonlamellar liquid crystalline particles by using DSPE-mPEGs with three different block lengths of the hydrophilic PEG segment. The effects of lipid composition, PEG chain length, and temperature on the morphology and internal nanostructure of these self-assembled lipidic aqueous dispersions based...

  5. Fractal-Based Lightning Channel Length Estimation from Convex-Hull Flash Areas for DC3 Lightning Mapping Array Data

    Science.gov (United States)

    Bruning, Eric C.; Thomas, Ronald J.; Krehbiel, Paul R.; Rison, William; Carey, Larry D.; Koshak, William; Peterson, Harold; MacGorman, Donald R.

    2013-01-01

    We will use VHF Lightning Mapping Array data to estimate NOx per flash and per unit channel length, including the vertical distribution of channel length. What s the best way to find channel length from VHF sources? This paper presents the rationale for the fractal method, which is closely related to the box-covering method.

  6. One-dimensional thermal evolution calculation based on a mixing length theory: Application to Saturnian icy satellites

    Science.gov (United States)

    Kamata, S.

    2017-12-01

    Solid-state thermal convection plays a major role in the thermal evolution of solid planetary bodies. Solving the equation system for thermal evolution considering convection requires 2-D or 3-D modeling, resulting in large calculation costs. A 1-D calculation scheme based on mixing length theory (MLT) requires a much lower calculation cost and is suitable for parameter studies. A major concern for the MLT scheme is its accuracy due to a lack of detailed comparisons with higher dimensional schemes. In this study, I quantify its accuracy via comparisons of thermal profiles obtained by 1-D MLT and 3-D numerical schemes. To improve the accuracy, I propose a new definition of the mixing length (l), which is a parameter controlling the efficiency of heat transportation due to convection. Adopting this new definition of l, I investigate the thermal evolution of Dione and Enceladus under a wide variety of parameter conditions. Calculation results indicate that each satellite requires several tens of GW of heat to possess a 30-km-thick global subsurface ocean. Dynamical tides may be able to account for such an amount of heat, though their ices need to be highly viscous.

  7. Hydrogen bond based smart polymer for highly selective and tunable capture of multiply phosphorylated peptides.

    Science.gov (United States)

    Qing, Guangyan; Lu, Qi; Li, Xiuling; Liu, Jing; Ye, Mingliang; Liang, Xinmiao; Sun, Taolei

    2017-09-06

    Multisite phosphorylation is an important and common mechanism for finely regulating protein functions and subsequent cellular responses. However, this study is largely restricted by the difficulty to capture low-abundance multiply phosphorylated peptides (MPPs) from complex biosamples owing to the limitation of enrichment materials and their interactions with phosphates. Here we show that smart polymer can serve as an ideal platform to resolve this challenge. Driven by specific but tunable hydrogen bonding interactions, the smart polymer displays differential complexation with MPPs, singly phosphorylated and non-modified peptides. Importantly, MPP binding can be modulated conveniently and precisely by solution conditions, resulting in highly controllable MPP adsorption on material surface. This facilitates excellent performance in MPP enrichment and separation from model proteins and real biosamples. High enrichment selectivity and coverage, extraordinary adsorption capacities and recovery towards MPPs, as well as high discovery rates of unique phosphorylation sites, suggest its great potential in phosphoproteomics studies.Capture of low-abundance multiply phosphorylated peptides (MPPs) is difficult due to limitation of enrichment materials and their interactions with phosphates. Here the authors show, a smart polymer driven by specific but tunable hydrogen bonding interactions can differentially complex with MPPs, singly phosphorylated and non-modified peptides.

  8. Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

    International Nuclear Information System (INIS)

    Xu, Yurun; Chen, Dajun

    2017-01-01

    Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

  9. Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yurun; Chen, Dajun, E-mail: cdj@dhu.edu.cn

    2017-07-01

    Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

  10. Assessing the Credit Risk of Corporate Bonds Based on Factor Analysis and Logistic Regress Analysis Techniques: Evidence from New Energy Enterprises in China

    Directory of Open Access Journals (Sweden)

    Yuanxin Liu

    2018-05-01

    Full Text Available In recent years, new energy sources have ushered in tremendous opportunities for development. The difficulties to finance new energy enterprises (NEEs can be estimated through issuing corporate bonds. However, there are few scientific and reasonable methods to assess the credit risk of NEE bonds, which is not conducive to the healthy development of NEEs. Based on this, this paper analyzes the advantages and risks of NEEs issuing bonds and the main factors affecting the credit risk of NEE bonds, constructs a hybrid model for assessing the credit risk of NEE bonds based on factor analysis and logistic regress analysis techniques, and verifies the applicability and effectiveness of the model employing relevant data from 46 Chinese NEEs. The results show that the main factors affecting the credit risk of NEE bonds are internal factors involving the company’s profitability, solvency, operational ability, growth potential, asset structure and viability, and external factors including macroeconomic environment and energy policy support. Based on the empirical results and the exact situation of China’s NEE bonds, this article finally puts forward several targeted recommendations.

  11. Self-assembly of Hydrazide-based Heterodimers Driven by Hydrogen Bonding and Donor-Acceptor Interaction

    Institute of Scientific and Technical Information of China (English)

    FENG,Dai-Jun; WANG,Peng; LI,Xiao-Qiang; LI,Zhan-Ting

    2006-01-01

    A new series of hydrogen bonding-driven heterodimers have been self-assembled in chloroform from hydrazide-based monomers. Additional intermolecular donor-acceptor interaction between the electron-rich bis(p-phenylene)-34-crown-10 unit and the electron-deficient naphthalene diimide unit has been utilized to increase the stability of the dimmers, and pronounced cooperativity of the two discrete non-covalent forces to stabilize the dimer has been revealed by the quantitative 1H (2D) NMR and UV-Vis experiments.

  12. 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...

  13. Method for Car in Dangerous Action Detection by Means of Wavelet Multi Resolution Analysis Based on Appropriate Support Length of Base Function

    OpenAIRE

    Kohei Arai; Tomoko Nishikawa

    2013-01-01

    Multi-Resolution Analysis: MRA based on the mother wavelet function with which support length differs from the image of the automobile rear under run is performed, and the run characteristic of a car is searched for. Speed, deflection, etc. are analyzed and the method of detecting vehicles with high accident danger is proposed. The experimental results show that vehicles in a dangerous action can be detected by the proposed method.

  14. Giant negative thermal expansion in bonded MnCoGe-based compounds with Ni2In-type hexagonal structure.

    Science.gov (United States)

    Zhao, Ying-Ying; Hu, Feng-Xia; Bao, Li-Fu; Wang, Jing; Wu, Hui; Huang, Qing-Zhen; Wu, Rong-Rong; Liu, Yao; Shen, Fei-Ran; Kuang, Hao; Zhang, Ming; Zuo, Wen-Liang; Zheng, Xin-Qi; Sun, Ji-Rong; Shen, Bao-Gen

    2015-02-11

    MnCoGe-based compounds undergo a giant negative thermal expansion (NTE) during the martensitic structural transition from Ni2In-type hexagonal to TiNiSi-type orthorhombic structure. High-resolution neutron diffraction experiments revealed that the expansion of unit cell volume can be as large as ΔV/V ∼ 3.9%. The optimized compositions with concurrent magnetic and structural transitions have been studied for magnetocaloric effect. However, these materials have not been considered as NTE materials partially due to the limited temperature window of phase transition. The as-prepared MnCoGe-based compounds are quite brittle and naturally collapse into powders. By using a few percents (3-4%) of epoxy to bond the powders, we introduced residual stress in the bonded samples and thus realized the broadening of structural transition by utilizing the specific characteristics of lattice softening enforced by the stress. As a result, giant NTE (not only the linear NTE coefficient α but also the operation-temperature window) has been achieved. For example, the average α̅ as much as -51.5 × 10(-6)/K with an operating temperature window as wide as 210 K from 122 to 332 K has been observed in a bonded MnCo0.98Cr0.02Ge compound. Moreover, in the region between 250 and 305 K near room temperature, the α value (-119 × 10(-6)/K) remains nearly independent of temperature. Such an excellent performance exceeds that of most other materials reported previously, suggesting it can potentially be used as a NTE material, particularly for compensating the materials with large positive thermal expansions.

  15. Eutectic-based wafer-level-packaging technique for piezoresistive MEMS accelerometers and bond characterization using molecular dynamics simulations

    Science.gov (United States)

    Aono, T.; Kazama, A.; Okada, R.; Iwasaki, T.; Isono, Y.

    2018-03-01

    We developed a eutectic-based wafer-level-packaging (WLP) technique for piezoresistive micro-electromechanical systems (MEMS) accelerometers on the basis of molecular dynamics analyses and shear tests of WLP accelerometers. The bonding conditions were experimentally and analytically determined to realize a high shear strength without solder material atoms diffusing to adhesion layers. Molecular dynamics (MD) simulations and energy dispersive x-ray (EDX) spectrometry done after the shear tests clarified the eutectic reaction of the solder materials used in this research. Energy relaxation calculations in MD showed that the diffusion of solder material atoms into the adhesive layer was promoted at a higher temperature. Tensile creep MD simulations also suggested that the local potential energy in a solder material model determined the fracture points of the model. These numerical results were supported by the shear tests and EDX analyses for WLP accelerometers. Consequently, a bonding load of 9.8 kN and temperature of 300 °C were found to be rational conditions because the shear strength was sufficient to endure the polishing process after the WLP process and there was little diffusion of solder material atoms to the adhesion layer. Also, eutectic-bonding-based WLP was effective for controlling the attenuation of the accelerometers by determining the thickness of electroplated solder materials that played the role of a cavity between the accelerometers and lids. If the gap distance between the two was less than 6.2 µm, the signal gains for x- and z-axis acceleration were less than 20 dB even at the resonance frequency due to air-damping.

  16. The earthing system of the PRIMA Neutral Beam Test Facility based on the Mesh Common Bonding Network topology

    International Nuclear Information System (INIS)

    Pomaro, Nicola; Boldrin, Marco; Lazzaro, Gabriele

    2015-01-01

    Highlights: • We designed a high performance earthing system for the ITER Neutral Beam Test Facility. • The system is based on the Mesh Common Bonded Network topology. • Careful bonding of all metallic structures allowed to obtain a well meshed system. • Special care was dedicated to improve EMC performance of critical areas like control rooms. • The facility experimental results will be representative also of the ITER situation. - Abstract: PRIMA is a large experimental facility under realization in Padova, aimed at developing and testing the Neutral Beam Injectors for ITER. The operation of these devices involves high RF power and voltage up to 1 MV. Frequent and high voltage electrical breakdowns inside the beam sources occur regularly. The presence of a distributed carefully optimized earthing system is of paramount importance to achieve a satisfying disturbances immunity for equipment and diagnostics. The paper describes the design and the realization of the earthing system of the PRIMA facility, which is based on the MESH-Common Bonding Network (MESH-CBN) topology, as recommended by IEC and IEEE standards for installations with high levels of Electromagnetic Interferences (EMI). The principles of the MESH-CBN approach were adapted to the PRIMA layout, which is composed by several buildings, that are independent for seismic and architectural reasons, but are linked by many electrical conduits and hydraulic pipelines. The availability of huge foundations, with a large number of poles and pillars, was taken into account; building parts dedicated to host control rooms and sensitive equipment were treated with particular care. Moreover, the lightning protection system was integrated and harmonized with the earthing system.

  17. The earthing system of the PRIMA Neutral Beam Test Facility based on the Mesh Common Bonding Network topology

    Energy Technology Data Exchange (ETDEWEB)

    Pomaro, Nicola, E-mail: nicola.pomaro@igi.cnr.it; Boldrin, Marco; Lazzaro, Gabriele

    2015-10-15

    Highlights: • We designed a high performance earthing system for the ITER Neutral Beam Test Facility. • The system is based on the Mesh Common Bonded Network topology. • Careful bonding of all metallic structures allowed to obtain a well meshed system. • Special care was dedicated to improve EMC performance of critical areas like control rooms. • The facility experimental results will be representative also of the ITER situation. - Abstract: PRIMA is a large experimental facility under realization in Padova, aimed at developing and testing the Neutral Beam Injectors for ITER. The operation of these devices involves high RF power and voltage up to 1 MV. Frequent and high voltage electrical breakdowns inside the beam sources occur regularly. The presence of a distributed carefully optimized earthing system is of paramount importance to achieve a satisfying disturbances immunity for equipment and diagnostics. The paper describes the design and the realization of the earthing system of the PRIMA facility, which is based on the MESH-Common Bonding Network (MESH-CBN) topology, as recommended by IEC and IEEE standards for installations with high levels of Electromagnetic Interferences (EMI). The principles of the MESH-CBN approach were adapted to the PRIMA layout, which is composed by several buildings, that are independent for seismic and architectural reasons, but are linked by many electrical conduits and hydraulic pipelines. The availability of huge foundations, with a large number of poles and pillars, was taken into account; building parts dedicated to host control rooms and sensitive equipment were treated with particular care. Moreover, the lightning protection system was integrated and harmonized with the earthing system.

  18. Micromechanics-based determination of effective elastic properties of polymer bonded explosives

    International Nuclear Information System (INIS)

    Banerjee, Biswajit; Adams, D.O.

    2003-01-01

    Polymer bonded explosives are particulate composites containing a high volume fraction of stiff elastic explosive particles in a compliant viscoelastic binder. Since the volume fraction of particles can be greater than 0.9 and the modulus contrast greater than 20 000, rigorous bounds on the elastic moduli of the composite are an order of magnitude different from experimentally determined values. Analytical solutions are also observed to provide inaccurate estimates of effective elastic properties. Direct finite element approximations of effective properties require large computational resources because of the complexity of the microstructure of these composites. An alternative approach, the recursive cells method (RCM) is also explored in this work. Results show that the degree of discretization and the microstructures used in finite element models of PBXs can significantly affect the estimated Young's moduli

  19. Particle Based Alloying by Accumulative Roll Bonding in the System Al-Cu

    Directory of Open Access Journals (Sweden)

    Mathias Göken

    2011-11-01

    Full Text Available The formation of alloys by particle reinforcement during accumulative roll bonding (ARB, and subsequent annealing, is introduced on the basis of the binary alloy system Al-Cu, where strength and electrical conductivity are examined in different microstructural states. An ultimate tensile strength (UTS of 430 MPa for Al with 1.4 vol.% Cu was reached after three ARB cycles, which almost equals UTS of the commercially available Al-Cu alloy AA2017A with a similar copper content. Regarding electrical conductivity, the UFG structure had no significant influence. Alloying of aluminum with copper leads to a linear decrease in conductivity of 0.78 µΩ∙cm/at.% following the Nordheim rule. On the copper-rich side, alloying with aluminum leads to a slight strengthening, but drastically reduces conductivity. A linear decrease of electrical conductivity of 1.19 µΩ∙cm/at.% was obtained.

  20. Functional organic materials based on polymerized liquid-crystal monomers: supramolecular hydrogen-bonded systems.

    Science.gov (United States)

    Broer, Dirk J; Bastiaansen, Cees M W; Debije, Michael G; Schenning, Albertus P H J

    2012-07-16

    Functional organic materials are of great interest for a variety of applications. To obtain precise functional properties, well-defined hierarchically ordered supramolecular materials are crucial. The self-assembly of liquid crystals has proven to be an extremely useful tool in the development of well-defined nanostructured materials. We have chosen the illustrative example of photopolymerizable hydrogen-bonding mesogens to show that a wide variety of functional materials can be made from a relatively simple set of building blocks. Upon mixing these compounds with other reactive mesogens, nematic, chiral nematic, and smectic or columnar liquid-crystalline phases can be formed that can be applied as actuators, sensors and responsive reflectors, and nanoporous membranes, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Printable optical sensors based on H-bonded supramolecular cholesteric liquid crystal networks.

    Science.gov (United States)

    Herzer, Nicole; Guneysu, Hilal; Davies, Dylan J D; Yildirim, Derya; Vaccaro, Antonio R; Broer, Dirk J; Bastiaansen, Cees W M; Schenning, Albertus P H J

    2012-05-09

    A printable H-bonded cholesteric liquid crystal (CLC) polymer film has been fabricated that, after conversion to a hygroscopic polymer salt film, responds to temperature and humidity by changing its reflection color. Fast-responding humidity sensors have been made in which the reflection color changes between green and yellow depending on the relative humidity. The change in reflection band is a result of a change in helix pitch in the film due to absorption and desorption of water, resulting in swelling/deswelling of the film material. When the polymer salt was saturated with water, a red-reflecting film was obtained that can potentially act as a time/temperature integrator. Finally, the films were printed on a foil, showing the potential application of supramolecular CLC materials as low-cost, printable, battery-free optical sensors.

  2. Laser-based surface patterning of composite plates for improved secondary adhesive bonding

    KAUST Repository

    Tao, Ran

    2018-03-01

    The effects of laser irradiation surface pretreatments on the mode I fracture toughness of adhesively bonded composite joints were evaluated. First, pulsed CO2 laser irradiation was uniformly deployed on carbon fiber reinforced polymer (CFRP) substrates. Next, double cantilever beam (DCB) tests were performed to assess the effects of surface pretreatments on the mode I fracture toughness of the adhesive joints. Then, a thoughtful combination of the proposed surface pretreatments was deployed to fabricate DCB specimens with patterned interfaces. A wide range of techniques, including X-ray photoelectron spectroscopy (XPS), contact profilometry, and optical and scanning electron microscopy (SEM) were used to ascertain the effects of all investigated surface pretreatments. It is shown that patterning promoted damage mechanisms that were not observed in the uniformly treated interfaces, resulting in an effective fracture toughness well above that predicted by a classical rule of mixture.

  3. Laser-based surface patterning of composite plates for improved secondary adhesive bonding

    KAUST Repository

    Tao, Ran; Alfano, Marco; Lubineau, Gilles

    2018-01-01

    The effects of laser irradiation surface pretreatments on the mode I fracture toughness of adhesively bonded composite joints were evaluated. First, pulsed CO2 laser irradiation was uniformly deployed on carbon fiber reinforced polymer (CFRP) substrates. Next, double cantilever beam (DCB) tests were performed to assess the effects of surface pretreatments on the mode I fracture toughness of the adhesive joints. Then, a thoughtful combination of the proposed surface pretreatments was deployed to fabricate DCB specimens with patterned interfaces. A wide range of techniques, including X-ray photoelectron spectroscopy (XPS), contact profilometry, and optical and scanning electron microscopy (SEM) were used to ascertain the effects of all investigated surface pretreatments. It is shown that patterning promoted damage mechanisms that were not observed in the uniformly treated interfaces, resulting in an effective fracture toughness well above that predicted by a classical rule of mixture.

  4. 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

  5. Base substitutions at scissile bond sites are sufficient to alter RNA-binding and cleavage activity of RNase III.

    Science.gov (United States)

    Kim, Kyungsub; Sim, Se-Hoon; Jeon, Che Ok; Lee, Younghoon; Lee, Kangseok

    2011-02-01

    RNase III, a double-stranded RNA-specific endoribonuclease, degrades bdm mRNA via cleavage at specific sites. To better understand the mechanism of cleavage site selection by RNase III, we performed a genetic screen for sequences containing mutations at the bdm RNA cleavage sites that resulted in altered mRNA stability using a transcriptional bdm'-'cat fusion construct. While most of the isolated mutants showed the increased bdm'-'cat mRNA stability that resulted from the inability of RNase III to cleave the mutated sequences, one mutant sequence (wt-L) displayed in vivo RNA stability similar to that of the wild-type sequence. In vivo and in vitro analyses of the wt-L RNA substrate showed that it was cut only once on the RNA strand to the 5'-terminus by RNase III, while the binding constant of RNase III to this mutant substrate was moderately increased. A base substitution at the uncleaved RNase III cleavage site in wt-L mutant RNA found in another mutant lowered the RNA-binding affinity by 11-fold and abolished the hydrolysis of scissile bonds by RNase III. Our results show that base substitutions at sites forming the scissile bonds are sufficient to alter RNA cleavage as well as the binding activity of RNase III. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  6. 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.

  7. 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.

  8. Copeptin is associated with kidney length, renal function, and prevalence of simple cysts in a population-based study.

    Science.gov (United States)

    Ponte, Belen; Pruijm, Menno; Ackermann, Daniel; Vuistiner, Philippe; Guessous, Idris; Ehret, Georg; Alwan, Heba; Youhanna, Sonia; Paccaud, Fred; Mohaupt, Markus; Péchère-Bertschi, Antoinette; Vogt, Bruno; Burnier, Michel; Martin, Pierre-Yves; Devuyst, Olivier; Bochud, Murielle

    2015-06-01

    Arginine vasopressin (AVP) has a key role in osmoregulation by facilitating water transport in the collecting duct. Recent evidence suggests that AVP may have additional effects on renal function and favor cyst growth in polycystic kidney disease. Whether AVP also affects kidney structure in the general population is unknown. We analyzed the association of copeptin, an established surrogate for AVP, with parameters of renal function and morphology in a multicentric population-based cohort. Participants from families of European ancestry were randomly selected in three Swiss cities. We used linear multilevel regression analysis to explore the association of copeptin with renal function parameters as well as kidney length and the presence of simple renal cysts assessed by ultrasound examination. Copeptin levels were log-transformed. The 529 women and 481 men had median copeptin levels of 3.0 and 5.2 pmol/L, respectively (P<0.001). In multivariable analyses, the copeptin level was associated inversely with eGFR (β=-2.1; 95% confidence interval [95% CI], -3.3 to -0.8; P=0.002) and kidney length (β=-1.2; 95% CI, -1.9 to -0.4; P=0.003) but positively with 24-hour urinary albumin excretion (β=0.11; 95% CI, 0.01 to 0.20; P=0.03) and urine osmolality (β=0.08; 95% CI, 0.05 to 0.10; P<0.001). A positive association was found between the copeptin level and the presence of renal cysts (odds ratio, 1.6; 95% CI, 1.1 to 2.4; P=0.02). These results suggest that AVP has a pleiotropic role in renal function and may favor the development of simple renal cysts. Copyright © 2015 by the American Society of Nephrology.

  9. VLSI Design of a Variable-Length FFT/IFFT Processor for OFDM-Based Communication Systems

    Directory of Open Access Journals (Sweden)

    Jen-Chih Kuo

    2003-12-01

    Full Text Available The technique of {orthogonal frequency division multiplexing (OFDM} is famous for its robustness against frequency-selective fading channel. This technique has been widely used in many wired and wireless communication systems. In general, the {fast Fourier transform (FFT} and {inverse FFT (IFFT} operations are used as the modulation/demodulation kernel in the OFDM systems, and the sizes of FFT/IFFT operations are varied in different applications of OFDM systems. In this paper, we design and implement a variable-length prototype FFT/IFFT processor to cover different specifications of OFDM applications. The cached-memory FFT architecture is our suggested VLSI system architecture to design the prototype FFT/IFFT processor for the consideration of low-power consumption. We also implement the twiddle factor butterfly {processing element (PE} based on the {{coordinate} rotation digital computer (CORDIC} algorithm, which avoids the use of conventional multiplication-and-accumulation unit, but evaluates the trigonometric functions using only add-and-shift operations. Finally, we implement a variable-length prototype FFT/IFFT processor with TSMC 0.35 μm 1P4M CMOS technology. The simulations results show that the chip can perform (64-2048-point FFT/IFFT operations up to 80 MHz operating frequency which can meet the speed requirement of most OFDM standards such as WLAN, ADSL, VDSL (256∼2K, DAB, and 2K-mode DVB.

  10. I-line stepper based overlay evaluation method for wafer bonding applications

    Science.gov (United States)

    Kulse, P.; Sasai, K.; Schulz, K.; Wietstruck, M.

    2018-03-01

    In the last decades the semiconductor technology has been driven by Moore's law leading to high performance CMOS technologies with feature sizes of less than 10 nm [1]. It has been pointed out that not only scaling but also the integration of novel components and technology modules into CMOS/BiCMOS technologies is becoming more attractive to realize smart and miniaturized systems [2]. Driven by new applications in the area of communication, health and automation, new components and technology modules such as BiCMOS embedded RF-MEMS, high-Q passives, Sibased microfluidics and InP-SiGe BiCMOS heterointegration have been demonstrated [3-6]. In contrast to standard VLSI processes fabricated on front side of the silicon wafer, these new technology modules additionally require to process the backside of the wafer; thus require an accurate alignment between the front and backside of the wafer. In previous work an advanced back to front side alignment technique and implementation into IHP's 0.25/0.13 µm high performance SiGe:C BiCMOS backside process module has been presented [7]. The developed technique enables a high resolution and accurate lithography on the backside of BiCMOS wafer for additional backside processing. In addition to the aforementioned back side process technologies, new applications like Through-Silicon Vias (TSV) for interposers and advanced substrate technologies for 3D heterogeneous integration demand not only single wafer fabrication but also processing of wafer stacks provided by temporary and permanent wafer bonding [8-9]. In this work, the non-contact infrared alignment system of the Nikon® i-line Stepper NSR-SF150 for both alignment and the overlay determination of bonded wafer stacks with embedded alignment marks are used to achieve an accurate alignment between the different wafer sides. The embedded field image alignment (FIA) marks of the interface and the device wafer top layer are measured in a single measurement job. By taking the

  11. Thermal barrier coatings with a double-layer bond coat on Ni{sub 3}Al based single-crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xin [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Xu, Zhenhua; Mu, Rende [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); He, Limin, E-mail: he_limin@yahoo.com [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Huang, Guanghong [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Cao, Xueqiang, E-mail: xcao@ciac.ac.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2014-04-05

    Highlights: • Thermal barrier coatings with a double-layer bond coat of (Ni,Pt)Al and NiCrAlYSi. • Good adherence at all interfaces within TBC system. • The underlying (Ni,Pt)Al layer can supply abundant Al content for the upper NiCrAlYSi layer. • Crack nucleation, propagation and coalescence lead to the failure of coating. -- Abstract: Electron-beam physical vapor deposited thermal barrier coatings (TBCs) with a double-layer bond coat of (Ni,Pt)Al and NiCrAlYSi were prepared on a Ni{sub 3}Al based single-crystal superalloy. Phase and cross-sectional microstructure of the developed coatings were studied by using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The experimental results show good adherence at all interfaces within this system. Furthermore, oxidation resistance and elements interdiffusion behavior of the double-layer bond coat were also investigated. The double-layer bond coat system exhibits a better scale adherence than the single layer bond coat systems since the underlying (Ni,Pt)Al layer can supply abundant Al for the upper NiCrAlYSi layer. Finally, thermal cycling behavior of the double-layer bond coat TBC was evaluated and the failure mechanism was discussed. Crack nucleation, propagation and coalescence caused by TGO growth stress and the thermal expansion mismatch stress between TGO and bond coat can be mainly responsible for the spallation of this coating.

  12. 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.

  13. Investigating the Effect of Recruitment Variability on Length-Based Recruitment Indices for Antarctic Krill Using an Individual-Based Population Dynamics Model

    Science.gov (United States)

    Thanassekos, Stéphane; Cox, Martin J.; Reid, Keith

    2014-01-01

    Antarctic krill (Euphausia superba; herein krill) is monitored as part of an on-going fisheries observer program that collects length-frequency data. A krill feedback management programme is currently being developed, and as part of this development, the utility of data-derived indices describing population level processes is being assessed. To date, however, little work has been carried out on the selection of optimum recruitment indices and it has not been possible to assess the performance of length-based recruitment indices across a range of recruitment variability. Neither has there been an assessment of uncertainty in the relationship between an index and the actual level of recruitment. Thus, until now, it has not been possible to take into account recruitment index uncertainty in krill stock management or when investigating relationships between recruitment and environmental drivers. Using length-frequency samples from a simulated population – where recruitment is known – the performance of six potential length-based recruitment indices is assessed, by exploring the index-to-recruitment relationship under increasing levels of recruitment variability (from ±10% to ±100% around a mean annual recruitment). The annual minimum of the proportion of individuals smaller than 40 mm (F40 min, %) was selected because it had the most robust index-to-recruitment relationship across differing levels of recruitment variability. The relationship was curvilinear and best described by a power law. Model uncertainty was described using the 95% prediction intervals, which were used to calculate coverage probabilities and assess model performance. Despite being the optimum recruitment index, the performance of F40 min degraded under high (>50%) recruitment variability. Due to the persistence of cohorts in the population over several years, the inclusion of F40 min values from preceding years in the relationship used to estimate recruitment in a given year improved its

  14. 1 mil gold bond wire study.

    Energy Technology Data Exchange (ETDEWEB)

    Huff, Johnathon; McLean, Michael B.; Jenkins, Mark W.; Rutherford, Brian Milne

    2013-05-01

    In microcircuit fabrication, the diameter and length of a bond wire have been shown to both affect the current versus fusing time ratio of a bond wire as well as the gap length of the fused wire. This study investigated the impact of current level on the time-to-open and gap length of 1 mil by 60 mil gold bond wires. During the experiments, constant current was provided for a control set of bond wires for 250ms, 410ms and until the wire fused; non-destructively pull-tested wires for 250ms; and notched wires. The key findings were that as the current increases, the gap length increases and 73% of the bond wires will fuse at 1.8A, and 100% of the wires fuse at 1.9A within 60ms. Due to the limited scope of experiments and limited data analyzed, further investigation is encouraged to confirm these observations.

  15. Adaptable liquid crystal elastomers with transesterification-based bond exchange reactions.

    Science.gov (United States)

    Hanzon, Drew W; Traugutt, Nicholas A; McBride, Matthew K; Bowman, Christopher N; Yakacki, Christopher M; Yu, Kai

    2018-02-14

    Adaptable liquid crystal elastomers (LCEs) have recently emerged to provide a new and robust method to program monodomain LCE samples. When a constant stress is applied with active bond exchange reactions (BERs), polymer chains and mesogens gradually align in the strain direction. Mesogen alignment is maintained after removing the BER stimulus (e.g. by lowering the temperature) and the programmed LCE samples exhibit free-standing two-way shape switching behavior. Here, a new adaptable main-chain LCE system was developed with thermally induced transesterification BERs. The network combines the conventional properties of LCEs, such as an isotropic phase transition and soft elasticity, with the dynamic features of adaptable network polymers, which are malleable to stress relaxation due to the BERs. Polarized Fourier transform infrared measurements confirmed the alignment of polymer chains and mesogens after strain-induced programming. The influence of the creep stress, temperature, and time on the strain amplitude of two-way shape switching was examined. The LCE network demonstrates an innovative feature of reprogrammability, where the reversible shape-switching memory of programmed LCEs is readily deleted by free-standing heating as random BERs disrupt the mesogen alignment, so LCEs are reprogrammed after returning to the polydomain state. Due to the dynamic nature of the LCE network, it also exhibits a surface welding effect and can be fully dissolved in the organic solvent, which might be utilized for green and sustainable recycling of LCEs.

  16. Chlorhexidine and proanthocyanidin enhance the long-term bond strength of resin-based endodontic sealer

    Directory of Open Access Journals (Sweden)

    Thaís Fantinato Trindade

    2018-05-01

    Full Text Available Abstract The aim of this study was to evaluate the effects of proanthocyanidin (PA and chlorhexidine (CHX on the bond strength (BS, failure pattern, and resin-dentin interface morphology of the endodontic sealers EndoREZ and AH Plus after 24 h and 6 months of water storage. A total of 120 prepared bovine roots were divided into six groups: AH Plus, CHX+AH Plus, PA+AH Plus, EndoREZ, CHX+EndoREZ, and PA+EndoREZ. Dentin was treated for 1 or 5 min with 2% CHX or 15% PA, respectively. Roots were filled and stored in water for 24 h or 6 months (n = 10. Root slices were subjected to push-out test and scanning electron microscopy (SEM. Data were compared using two-way ANOVA and student's t-test (α = 5%. BS decreased over time for AH Plus and untreated EndoREZ (p 0.05. At 6 months, EndoREZ had higher BS values for CHX and PA than control (p 0.05. Cohesive and mixed failures were observed in all groups. SEM revealed sealer tags in the root dentin. In conclusion, BS decreased with time and AH Plus had higher BS than EndoREZ in untreated dentin; however, CHX or PA enhanced long-term BS of EndoREZ. Overall, dentin treatment affected failure pattern and resin-dentin interface morphology, particularly for EndoREZ.

  17. 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

  18. Characterizing Bonding Patterns in Diradicals and Triradicals by Density-Based Wave Function Analysis: A Uniform Approach.

    Science.gov (United States)

    Orms, Natalie; Rehn, Dirk R; Dreuw, Andreas; Krylov, Anna I

    2018-02-13

    Density-based wave function analysis enables unambiguous comparisons of the electronic structure computed by different methods and removes ambiguity of orbital choices. We use this tool to investigate the performance of different spin-flip methods for several prototypical diradicals and triradicals. In contrast to previous calibration studies that focused on energy gaps between high- and low spin-states, we focus on the properties of the underlying wave functions, such as the number of effectively unpaired electrons. Comparison of different density functional and wave function theory results provides insight into the performance of the different methods when applied to strongly correlated systems such as polyradicals. We show that canonical molecular orbitals for species like large copper-containing diradicals fail to correctly represent the underlying electronic structure due to highly non-Koopmans character, while density-based analysis of the same wave function delivers a clear picture of the bonding pattern.

  19. INCLUSION RATIO BASED ESTIMATOR FOR THE MEAN LENGTH OF THE BOOLEAN LINE SEGMENT MODEL WITH AN APPLICATION TO NANOCRYSTALLINE CELLULOSE

    Directory of Open Access Journals (Sweden)

    Mikko Niilo-Rämä

    2014-06-01

    Full Text Available A novel estimator for estimating the mean length of fibres is proposed for censored data observed in square shaped windows. Instead of observing the fibre lengths, we observe the ratio between the intensity estimates of minus-sampling and plus-sampling. It is well-known that both intensity estimators are biased. In the current work, we derive the ratio of these biases as a function of the mean length assuming a Boolean line segment model with exponentially distributed lengths and uniformly distributed directions. Having the observed ratio of the intensity estimators, the inverse of the derived function is suggested as a new estimator for the mean length. For this estimator, an approximation of its variance is derived. The accuracies of the approximations are evaluated by means of simulation experiments. The novel method is compared to other methods and applied to real-world industrial data from nanocellulose crystalline.

  20. 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.

  1. 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.

  2. A WEB-BASED SURVEY OF MOTHER-INFANT BOND, ATTACHMENT EXPERIENCES, AND METACOGNITION IN POSTTRAUMATIC STRESS FOLLOWING CHILDBIRTH.

    Science.gov (United States)

    Williams, Charlotte; Patricia Taylor, Emily; Schwannauer, Matthias

    2016-05-01

    Postnatal depression is linked to adverse outcomes for parent and child, with metacognition and parenting experiences key variables in the development and maintenance of depression. The attachment between mother and infant is especially vulnerable to the effects of untreated postnatal depression. Despite high levels of reported postnatal stress symptoms, less attention has been given the relationship between attachment, metacognition, and postnatal traumatic symptoms in the context of birth trauma. This study tested several hypotheses regarding the relationships between recalled parenting experiences, metacognition, postnatal symptoms of posttraumatic stress disorder and depression and perceptions of the mother-infant bond, confirming and extending upon metacognitive and mentalization theories. A Web-based, cross-sectional, self-report questionnaire design was employed in an analog sample of new mothers. Participants were 502 women recruited via open-access Web sites associated with birth organizations. Structural equation modeling was employed for the principal analysis. Metacognition fully mediated the relationship between recalled parenting experiences and postnatal psychological outcomes. Posttraumatic stress was indirectly associated with maternal perceptions of the bond, with this relationship mediated by depression. Metacognition may have a key role in postnatal psychological distress. Where postnatal depression or traumatic birth experiences are identified, screening for posttraumatic stress is strongly indicated. © 2016 Michigan Association for Infant Mental Health.

  3. Triboelectric-Nanogenerator-Based Soft Energy-Harvesting Skin Enabled by Toughly Bonded Elastomer/Hydrogel Hybrids.

    Science.gov (United States)

    Liu, Ting; Liu, Mengmeng; Dou, Su; Sun, Jiangman; Cong, Zifeng; Jiang, Chunyan; Du, Chunhua; Pu, Xiong; Hu, Weiguo; Wang, Zhong Lin

    2018-03-27

    A major challenge accompanying the booming next-generation soft electronics is providing correspondingly soft and sustainable power sources for driving such devices. Here, we report stretchable triboelectric nanogenerators (TENG) with dual working modes based on the soft hydrogel-elastomer hybrid as energy skins for harvesting biomechanical energies. The tough interfacial bonding between the hydrophilic hydrogel and hydrophobic elastomer, achieved by the interface modification, ensures the stable mechanical and electrical performances of the TENGs. Furthermore, the dehydration of this toughly bonded hydrogel-elastomer hybrid is significantly inhibited (the average dehydration decreases by over 73%). With PDMS as the electrification layer and hydrogel as the electrode, a stretchable, transparent (90% transmittance), and ultrathin (380 μm) single-electrode TENG was fabricated to conformally attach on human skin and deform as the body moves. The two-electrode mode TENG is capable of harvesting energy from arbitrary human motions (press, stretch, bend, and twist) to drive the self-powered electronics. This work provides a feasible technology to design soft power sources, which could potentially solve the energy issues of soft electronics.

  4. Evidence-based concepts and procedures for bonded inlays and onlays. Part II. Guidelines for cavity preparation and restoration fabrication.

    Science.gov (United States)

    Rocca, Giovanni Tommaso; Rizcalla, Nicolas; Krejci, Ivo; Dietschi, Didier

    2015-01-01

    The second part of this article series presents an evidence-based update of clinical protocols and procedures for cavity preparation and restoration selection for bonded inlays and onlays. More than ever, tissue conservation dictates preparation concepts, even though some minimal dimensions still have to be considered for all restorative materials. In cases of severe bruxism or tooth fragilization, CAD/CAM composite resins or pressed CAD/CAM lithium disilicate glass ceramics are often recommended, although this choice relies mainly on scarce in vitro research as there is still a lack of medium- to long-term clinical evidence. The decision about whether or not to cover a cusp can only be made after a multifactorial analysis, which includes cavity dimensions and the resulting tooth biomechanical status, as well as occlusal and esthetic factors. The clinical impact of the modern treatment concepts that were outlined in the previous article - Dual Bonding (DB)/Immediate Dentin Sealing (IDS), Cavity Design Optimization (CDO), and Cervical Margins Relocation (CMR) - are described in detail in this article and discussed in light of existing clinical and scientific evidence for simpler, more predictable, and more durable results. Despite the wide choice of restorative materials (composite resin or ceramic) and techniques (classical or CAD/CAM), the cavity for an indirect restoration should meet five objective criteria before the impression.

  5. Costs, length of stay, and mortality of super-refractory status epilepticus: A population-based study from Germany.

    Science.gov (United States)

    Strzelczyk, Adam; Ansorge, Sonja; Hapfelmeier, Jana; Bonthapally, Vijayveer; Erder, M Haim; Rosenow, Felix

    2017-09-01

    Super-refractory status epilepticus (SRSE) is a severe condition in which a patient in status epilepticus (SE) for ≥24 h does not respond to first-, second-, or third-line therapy. The economic impact of SRSE treatment remains unclear. A health insurance research database was used for a population-based estimation of SRSE-associated inpatient costs, length of stay, and mortality in Germany. An algorithm using International Classification of Diseases, 10th Edition coding and treatment parameters identified and classified patients in a German statutory health insurance database covering admissions from 2008 to 2013 as having refractory SE (RSE) or SRSE. Admissions data in our study refer to these classifications. Associated patient data included costs, procedures, and demographics. The algorithm identified 2,585 (all type) SE admissions, classified as 1,655 nonrefractory SE (64%), 592 (22.9%) RSE, and 338 (13.1%) SRSE, producing database incidence rates of 15.0 in 100,000, 5.2 in 100,000, and 3.0 in 100,000 per year, respectively. Median cost per admission was €4,063 for nonrefractory SE, €4,581 (p < 0.001) for RSE, and €32,706 (p < 0.001) for SRSE. Median length of stay varied significantly between 8 days (mean = 13.6) in nonrefractory SE, 14 days in RSE, and up to 37 days in SRSE. Discharge mortality increased from 9.6% in nonrefractory SE to 15.0% (p < 0.001) in RSE and 39.9% (p < 0.001) in SRSE. This study evaluated the hospital treatment costs associated with admissions classified by the algorithm as SRSE in Germany. SRSE represented 13% of all SE admissions, but resulted in 56% of all SE-related costs. The lack of approved treatments and limited number of evidence-based treatment guidelines highlight the need for further evaluations of the SRSE burden of illness and the potential for further optimization of treatments for SRSE. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

  6. Molecular heterogeneous catalysts derived from bipyridine-based organosilica nanotubes for C-H bond activation.

    Science.gov (United States)

    Zhang, Shengbo; Wang, Hua; Li, Mei; Han, Jinyu; Liu, Xiao; Gong, Jinlong

    2017-06-01

    Heterogeneous metal complex catalysts for direct C-H activation with high activity and durability have always been desired for transforming raw materials into feedstock chemicals. This study described the design and synthesis of one-dimensional organosilica nanotubes containing 2,2'-bipyridine (bpy) ligands in the framework (BPy-NT) and their post-synthetic metalation to provide highly active and robust molecular heterogeneous catalysts. By adjusting the ratios of organosilane precursors, very short BPy-NT with ∼50 nm length could be controllably obtained. The post-synthetic metalation of bipyridine-functionalized nanotubes with [IrCp*Cl(μ-Cl)] 2 (Cp* = η 5 -pentamethylcyclopentadienyl) and [Ir(cod)(OMe)] 2 (cod = 1,5-cyclooctadiene) afforded solid catalysts, IrCp*-BPy-NT and Ir(cod)-BPy-NT, which were utilized for C-H oxidation of heterocycles and cycloalkanes as well as C-H borylation of arenes. The cut-short nanotube catalysts displayed enhanced activities and durability as compared to the analogous homogeneous catalysts and other conventional heterogeneous catalysts, benefiting from the isolated active sites as well as the fast transport of substrates and products. After the reactions, a detailed characterization of Ir-immobilized BPy-NT via TEM, SEM, nitrogen adsorption, UV/vis, XPS, and 13 C CP MAS NMR indicated the molecular nature of the active species as well as stable structures of nanotube scaffolds. This study demonstrates the potential of BPy-NT with a short length as an integration platform for the construction of efficient heterogeneous catalytic systems for organic transformations.

  7. Study of the length of hospital stay for free flap reconstruction of oral and pharyngeal cancer in the context of the new French casemix-based funding.

    Science.gov (United States)

    Girod, Angélique; Brancati, Antonio; Mosseri, Véronique; Kriegel, Irène; Jouffroy, Thomas; Rodriguez, José

    2010-03-01

    The French national health insurance reimbursement system has recently changed from a global hospital funding system to casemix-based funding. The authors studied the factors likely to influence the length of hospital stay for free flap reconstructions after surgery for cancers of the oral cavity or pharynx. Data concerning 207 oral cavity or pharynx free flap reconstructions were extracted from a prospective registration. Lengths of hospital stay were compared by an analysis of variance F test or a nonparametric Kruskal-Wallis test, and transfusion rates were compared by Chi-square test or Fisher's exact test, as appropriate. The median length of hospital stay was 24 days (range: 7-145 days). Length of hospital stay was significantly longer according to the type of flap (pcasemix-based funding, this study raises the problem of harvesting of the fibula flap, management of preoperative haemoglobin and nutritional status. (c) 2009 Elsevier Ltd. All rights reserved.

  8. Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study.

    Science.gov (United States)

    Lau, Mayank; Amarnath, G S; Muddugangadhar, B C; Swetha, M U; Das, Kopal Anshuraj Ashok Kumar

    2014-04-01

    The condition of the denture bearing tissues may be adversely affected by high stress concentration during function. Chairside Denture (Hard and Soft) reliners are used to distribute forces applied to soft tissues during function. Tensile and shear bond strength has been shown to be dependent on their chemical composition. A weak bond could harbor bacteria, promote staining and delamination of the lining material. To investigate tensile and shear bond strength of 4 different commercially available denture relining materials to conventional heat cured acrylic denture base resin. 4 mm sections in the middle of 160 Acrylic cylindrical specimens (20 mm x 8 mm) were removed, packed with test materials (Mollosil, G C Reline Soft, G C Reline Hard (Kooliner) and Ufi Gel Hard and polymerized. Specimens were divided into 8 groups of 20 each. Tensile and shear bond strength to the conventional heat cured acrylic denture base resin were examined by Instron Universal Tensile Testing Machine using the equation F=N/A (F-maximum force exerted on the specimen (Newton) and A-bonding area= 50.24 mm2). One-way ANOVA was used for multiple group comparisons followed by Bonferroni Test and Hsu's MCB for multiple pairwise comparisons to asses any significant differences between the groups. The highest mean Tensile bond strength value was obtained for Ufi Gel Hard (6.49+0.08 MPa) and lowest for G C Reline Soft (0.52+0.01 MPa). The highest mean Shear bond strength value was obtained for Ufi Gel Hard (16.19+0.1 MPa) and lowest for Mollosil (0.59+0.05 MPa). The Benferroni test showed a significant difference in the mean tensile bond strength and the mean shear bond strength when the two denture soft liners were compared as well as when the two denture hard liners were compared. Hsu's MCB implied that Ufi gel hard is better than its other closest competitors. The Tensile and Shear bond strength values of denture soft reliners were significantly lower than denture hard reliners. How to cite the

  9. 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...

  10. A Component-Based Study of the Effect of Diameter on Bond and Anchorage Characteristics of Blind-Bolted Connections.

    Directory of Open Access Journals (Sweden)

    Muhammad Nasir Amin

    Full Text Available Structural hollow sections are gaining worldwide importance due to their structural and architectural advantages over open steel sections. The only obstacle to their use is their connection with other structural members. To overcome the obstacle of tightening the bolt from one side has given birth to the concept of blind bolts. Blind bolts, being the practical solution to the connection hindrance for the use of hollow and concrete filled hollow sections play a vital role. Flowdrill, the Huck High Strength Blind Bolt and the Lindapter Hollobolt are the well-known commercially available blind bolts. Although the development of blind bolts has largely resolved this issue, the use of structural hollow sections remains limited to shear resistance. Therefore, a new modified version of the blind bolt, known as the "Extended Hollo-Bolt" (EHB due to its enhanced capacity for bonding with concrete, can overcome the issue of low moment resistance capacity associated with blind-bolted connections. The load transfer mechanism of this recently developed blind bolt remains unclear, however. This study uses a parametric approach to characterising the EHB, using diameter as the variable parameter. Stiffness and load-carrying capacity were evaluated at two different bolt sizes. To investigate the load transfer mechanism, a component-based study of the bond and anchorage characteristics was performed by breaking down the EHB into its components. The results of the study provide insight into the load transfer mechanism of the blind bolt in question. The proposed component-based model was validated by a spring model, through which the stiffness of the EHB was compared to that of its components combined. The combined stiffness of the components was found to be roughly equivalent to that of the EHB as a whole, validating the use of this component-based approach.

  11. A Component-Based Study of the Effect of Diameter on Bond and Anchorage Characteristics of Blind-Bolted Connections.

    Science.gov (United States)

    Amin, Muhammad Nasir; Zaheer, Salman; Alazba, Abdulrahman Ali; Saleem, Muhammad Umair; Niazi, Muhammad Umar Khan; Khurram, Nauman; Amin, Muhammad Tahir

    2016-01-01

    Structural hollow sections are gaining worldwide importance due to their structural and architectural advantages over open steel sections. The only obstacle to their use is their connection with other structural members. To overcome the obstacle of tightening the bolt from one side has given birth to the concept of blind bolts. Blind bolts, being the practical solution to the connection hindrance for the use of hollow and concrete filled hollow sections play a vital role. Flowdrill, the Huck High Strength Blind Bolt and the Lindapter Hollobolt are the well-known commercially available blind bolts. Although the development of blind bolts has largely resolved this issue, the use of structural hollow sections remains limited to shear resistance. Therefore, a new modified version of the blind bolt, known as the "Extended Hollo-Bolt" (EHB) due to its enhanced capacity for bonding with concrete, can overcome the issue of low moment resistance capacity associated with blind-bolted connections. The load transfer mechanism of this recently developed blind bolt remains unclear, however. This study uses a parametric approach to characterising the EHB, using diameter as the variable parameter. Stiffness and load-carrying capacity were evaluated at two different bolt sizes. To investigate the load transfer mechanism, a component-based study of the bond and anchorage characteristics was performed by breaking down the EHB into its components. The results of the study provide insight into the load transfer mechanism of the blind bolt in question. The proposed component-based model was validated by a spring model, through which the stiffness of the EHB was compared to that of its components combined. The combined stiffness of the components was found to be roughly equivalent to that of the EHB as a whole, validating the use of this component-based approach.

  12. Detection of different-time-scale signals in the length of day variation based on EEMD analysis technique

    Directory of Open Access Journals (Sweden)

    Wenbin Shen

    2016-05-01

    Full Text Available Scientists pay great attention to different-time-scale signals in the length of day (LOD variations ΔLOD, which provide signatures of the Earth's interior structure, couplings among different layers, and potential excitations of ocean and atmosphere. In this study, based on the ensemble empirical mode decomposition (EEMD, we analyzed the latest time series of ΔLOD data spanning from January 1962 to March 2015. We observed the signals with periods and amplitudes of about 0.5 month and 0.19 ms, 1.0 month and 0.19 ms, 0.5 yr and 0.22 ms, 1.0 yr and 0.18 ms, 2.28 yr and 0.03 ms, 5.48 yr and 0.05 ms, respectively, in coincidence with the results of predecessors. In addition, some signals that were previously not definitely observed by predecessors were detected in this study, with periods and amplitudes of 9.13 d and 0.12 ms, 13.69 yr and 0.10 ms, respectively. The mechanisms of the LOD fluctuations of these two signals are still open.

  13. 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.

  14. Shear bond strength evaluation of resin composite to resin-modified glass-ionomer cement using three different resin adhesives vs. glass-ionomer based adhesive

    Directory of Open Access Journals (Sweden)

    Mostafa Sadeghi

    2015-12-01

    Full Text Available Background: The clinical success of sandwich technique depends on the strength of resin-modified glass ionomer cement (RMGIC bonding to both dentin and resin composite. Therefore, the shear bond strength (SBS of resin composite bonded to RMGIC utilizing different resin adhesives versus a GIC-based adhesive was compared. Materials and methods: In this in vitro study, 84 holes (5×2 mm were prepared in acrylic blocks, randomly divided into seven groups (n=12 and filled with RMGIC (Light-Cured Universal Restorative, GC. In the Group I; no adhesive was applied on the RMGIC. In the Group II, non-etched and Group III was etched with phosphoric acid. In groups II and III, after rinsing, etch-and-rinse adhesive (OptiBond Solo Plus; in the Group IV; a two-step self-etch adhesive (OptiBond XTR and in Group V; a one-step self-etch (OptiBond All-in-One were applied on the cement surfaces. Group VI; a GIC-based adhesive (Fuji Bond LC was painted over the cement surface and cured. Group VII; the GIC-based adhesive was brushed over RMGIC followed by the placement of resin composite and co-cured. Afterward; resin composite (Point 4 cylinders were placed on the treated cement surfaces. The specimens were placed in 100% humidity at 37 ± 1°C and thermo cycled. The shear bond test was performed at a cross-head speed of 1 mm/min and calculated in MPa; the specimens were examined to determine mode of failure. The results were analyzed using one-way ANOVA and Tukey test. Results: The maximum (24.62±3.70 MPa and minimum (18.15±3.38 MPa SBS mean values were recorded for OptiBond XTR adhesive and the control group, respectively. The pairwise comparisons showed no significant differences between the groups that bonded with different adhesives. The adhesive failure was the most common failure mode observed. Conclusion: This study suggests that GIC-based adhesive could be applied over RMGIC as co-cure technique for sandwich restorations in lieu of employing the resin

  15. The Comparative Studies of Binding Activity of Curcumin and Didemethylated Curcumin with Selenite: Hydrogen Bonding vs Acid-Base Interactions

    Science.gov (United States)

    Liao, Jiahn-Haur; Wu, Tzu-Hua; Chen, Ming-Yi; Chen, Wei-Ting; Lu, Shou-Yun; Wang, Yi-Hsuan; Wang, Shao-Pin; Hsu, Yen-Min; Huang, Yi-Shiang; Huang, Zih-You; Lin, Yu-Ching; Chang, Ching-Ming; Huang, Fu-Yung; Wu, Shih-Hsiung

    2015-12-01

    In this report, the in vitro relative capabilities of curcumin (CCM) and didemethylated curcumin (DCCM) in preventing the selenite-induced crystallin aggregation were investigated by turbidity tests and isothermal titration calorimetry (ITC). DCCM showed better activity than CCM. The conformers of CCM/SeO32- and DCCM/SeO32- complexes were optimized by molecular orbital calculations. Results reveal that the selenite anion surrounded by CCM through the H-bonding between CCM and selenite, which is also observed via IR and NMR studied. For DCCM, the primary driving force is the formation of an acid-base adduct with selenite showing that the phenolic OH group of DCCM was responsible for forming major conformer of DCCM. The formation mechanisms of selenite complexes with CCM or DCCM explain why DCCM has greater activity than CCM in extenuating the toxicity of selenite as to prevent selenite-induced lens protein aggregation.

  16. Depressive symptoms are not associated with leukocyte telomere length: findings from the Nova Scotia Health Survey (NSHS95, a population-based study.

    Directory of Open Access Journals (Sweden)

    Jonathan A Shaffer

    Full Text Available Premature shortening of leukocyte telomere length has been proposed as a novel mechanism by which depression may confer increased risk of adverse cardiovascular events. Prior studies demonstrating associations of depression and depressive symptoms with shorter leukocyte telomere length were small, included selected psychiatric outpatients, were based on convenience samples, and/or adjusted for a limited number of possible confounding factors.We examined the associations of depressive symptoms, probable depressive disorder, and specific depressive symptom clusters, as assessed by the Center for Epidemiological Studies--Depression (CES-D scale, with leukocyte telomere length, measured by using a real-time PCR method, in 2,225 apparently healthy participants from the 1995 Nova Scotia Health Survey population-based study. The mean age was 48.2 ± 18.9 years; 49.9% of participants were female; and the mean CES-D score was 7.4 ± 7.9. The mean telomere length was 5,301 ± 587 base pairs. In an unadjusted model, depressive symptoms were significantly associated with longer leukocyte telomere length (B = 27.6 base pairs per standard deviation increase in CES-D, 95% confidence interval [CI] = 3.1-52.1, p = 0.027. This association was no longer significant after adjustment for age and sex (B = 9.5, 95% CI = -14.6-33.6, p = 0.44 or after further adjustment for body mass index, Framingham risk score and previous history of ischemic heart disease (all p's ≥ 0.37. Neither probable depressive disorder nor specific depressive symptom clusters were independently associated with leukocyte telomere length.Concurrent depressive symptoms were not associated with leukocyte telomere length in a large, representative, population-based study.

  17. Length-scale dependent mechanical properties of Al-Cu eutectic alloy: Molecular dynamics based model and its experimental verification

    Science.gov (United States)

    Tiwary, C. S.; Chakraborty, S.; Mahapatra, D. R.; Chattopadhyay, K.

    2014-05-01

    This paper attempts to gain an understanding of the effect of lamellar length scale on the mechanical properties of two-phase metal-intermetallic eutectic structure. We first develop a molecular dynamics model for the in-situ grown eutectic interface followed by a model of deformation of Al-Al2Cu lamellar eutectic. Leveraging the insights obtained from the simulation on the behaviour of dislocations at different length scales of the eutectic, we present and explain the experimental results on Al-Al2Cu eutectic with various different lamellar spacing. The physics behind the mechanism is further quantified with help of atomic level energy model for different length scale as well as different strain. An atomic level energy partitioning of the lamellae and the interface regions reveals that the energy of the lamellae core are accumulated more due to dislocations irrespective of the length-scale. Whereas the energy of the interface is accumulated more due to dislocations when the length-scale is smaller, but the trend is reversed when the length-scale is large beyond a critical size of about 80 nm.

  18. 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…

  19. The influence of different bracket base surfaces on tensile and shear bond strength

    NARCIS (Netherlands)

    Algera, T.J.; Kleverlaan, C.J.; Prahl-Andersen, B.; Feilzer, A.J.

    2008-01-01

    Fracture of the bracket-cement-enamel system usually takes place between the bracket and the cement. Especially for glass ionomer-based materials, it is helpful if this part of the system can be improved. The aim of this in vitro study was to investigate the influence of different bracket base

  20. Effect of calcium hydroxide and double and triple antibiotic pastes on the bond strength of epoxy resin-based sealer to root canal dentin.

    Science.gov (United States)

    Akcay, Merve; Arslan, Hakan; Topcuoglu, Hüseyin Sinan; Tuncay, Oznur

    2014-10-01

    The aim of this study was to evaluate the effects of calcium hydroxide (CH) and triple (TAP) and double (DAP) antibiotic pastes on the bond strength of an epoxy resin-based sealer (AH Plus Jet; Dentsply DeTrey, Konstanz, Germany) to the root canal dentin. Sixty-four single-rooted human mandibular premolars were decoronated and prepared using the rotary system to size 40. The specimens were randomly divided into a control group (without intracanal dressing) and 3 experimental groups that received an intracanal dressing with either CH, DAP, or TAP (n = 16). The intracanal dressing was removed by rinsing with 10 mL 17% EDTA followed by 10 mL 2.5% sodium hypochlorite. The root canals were then obturated with gutta-percha and AH Plus Jet sealer. A push-out test was used to measure the bond strength between the root canal dentin and the sealer. The data were analyzed using 2-way analysis of variance and Tukey post hoc tests to detect the effect of the independent variables (intracanal medicaments and root canal thirds) and their interactions on the push-out bond strength of the root canal filling material to the root dentin (P = .05). The push-out bond strength values were significantly affected by the intracanal medicaments (P .05). In the middle and apical third, the bond strength of the TAP group was higher than those of the CH and DAP groups (P < .05). The DAP and CH did not affect the bond strength of the epoxy resin-based sealer. Additionally, the TAP improved the bond strength of the epoxy resin-based sealer in the middle and apical thirds. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  1. The Effect of Titanium Tetrafluoride and Sodium Hypochlorite on the Shear Bond Strength of Methacrylate and Silorane Based Composite Resins: an In-Vitro Study.

    Science.gov (United States)

    Sharafeddin, Farahnaz; Koohpeima, Fatemeh; Razazan, Nader

    2017-06-01

    The bond strength of composites with different adhesive systems with dentin is an important factor in long term durability of composite restorations. The effect of titanium tetrafluoride (TiF 4 ) as anti caries agent and sodium hypochlorite (NaOCl) as disinfectant on the shear bond of nanofilled and silorane based composite resins have not been investigated in previous studies. This study was conducted to determine bond strength between dentin and two composite systems, by means of shear bond test using TiF 4 and NaOCl. Middle dentin of 60 intact extracted maxillary premolar teeth were exposed by sectioning the crowns at a depth of 2mm from central groove and parallel to the occlusal surface. Standardized smear layer was created using a 600-grit silicon carbide paper and then samples were embedded in acrylic resin blocks. Then the samples were randomly divided into 6 \\groups summarized as Group I: Z350, Group II: Z350+ NaOCl, Group III: Z350+ TiF 4 , Group IV: P90, Group V: P90+ NaOCl, Group VI: P90+ TiF 4 according to manufacturer's instruction. Then samples were subjected to shear bond strength (SBS) test using universal testing machine and data were analyzed using ANOVA and Tukey tests ( p composite resin ( p = 0.004), and also silorane based composite resin ( p = 0.006). Application of 4% TiF 4 caused a significant increase in SBS of silorane based composite resin ( p = 0.001). The effect of TiF 4 on nanofilled composite was not statistically significant. Using TiF 4 has a positive effect on increasing the shear bond while NaOCl has negative effect on bond strength.

  2. Self-healing polymer gels based on dynamic covalent bonds%基于动态共价键的可自愈合聚合物凝胶

    Institute of Scientific and Technical Information of China (English)

    张云飞; 邓国华

    2012-01-01

    简要介绍了动态共价键既具有普通共价键的高强度和稳定性,又能像分子间作用力(如氢键)那样可逆地断裂和重组的特点,以及基于动态共价键构筑智能凝胶材料的优势。综述了多种动态共价键,如芳香基苯并呋喃酮二聚体(diarylbibenzo furanone,DABBF)、三硫酯(trithiocarbonate,TTC)、芳基硼酸酯、酰腙键(acylhydrazone bond)、双硫键(disulfide bond)等的结构及其动态化学,以及应用它们合成聚合物凝胶的方法、凝胶的自愈合机理和性能。提出了发现和采用多种动态共价键构筑可自愈合聚合物凝胶的趋势,为此须解决多种动态共价键的相容性、凝胶自愈合机理与性能的光谱表征等问题,并加强应用研究。%Dynamic covalent bonds have high mechanical strength and stability like ordinary covalent bonds and can reversibly break and rebuild like intermolecular forces(such as hydrogen bonding).The properties of dynamic covalent bonds are introduced.The advantages of building smart gels based on dynamic covalent bonds are described.Specifically,the structure and dynamic chemistry of diarylbibenzo furanone(DABBF),trithiocarbonate(TTC),phenylboronic aciddiol ester bond,acylhydrazone bond and disulfide bond are reviewed.The methods of utilizing those dynamic covalent bonds to construct dynamic gels with self-healing properties,including the healing mechanisms,are presented.Combining two or more covalent bonds to construct dynamic gels with more complex responsiveness are proposed.Problems,such as compatibility of the dynamic covalent bonds,spectroscopic methods for characterizing self-healing mechanisms and capabilities,and application-oriented systems need to be further investigated.

  3. Influence of pellet diameter and length on the quality of pellets and performance, nutrient utilisation and digestive tract development of broilers fed on wheat-based diets.

    Science.gov (United States)

    Abdollahi, M R; Ravindran, V; Wester, T J; Ravindran, G; Thomas, D V

    2013-06-01

    1. The influence of pellet diameter and length on the quality of pellets and performance, nutrient utilisation and digestive tract development of broilers given wheat-based diets was examined from 10 to 42 d of age. The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two pellet diameters (3 and 4.76 mm) and two pellet lengths (3 and 6 mm). From 0 to 9 d of age, all birds were offered a common starter diet pelleted with a 3-mm diameter die and 3-mm length. Broiler grower (d 10 to 21) and finisher (d 22 to 42) diets, based on wheat, were formulated and then subjected to the 4 different treatments. 2. In grower diets, increasing pellet diameter and pellet length reduced the gelatinised starch (GS) content of the diets. In finisher diets, GS content of 3-mm diameter pellets did not change with increasing pellet length but decreased in 4.76-mm diameter pellets. 3. In grower and finisher diets, increments in intact pellet weight, pellet durability index and pellet hardness with increasing pellet length were greater in 3-mm diameter pellets than those with 4.76-mm diameter. 4. Increasing pellet length from 3 to 6 mm increased apparent metabolisable energy values. Neither the interaction nor main effects were significant for the ileal digestibility of nitrogen and starch. 5. During the grower period (d 10 to 21), birds given pellets of 6-mm length had greater body-weight gain than those given 3-mm length pellets. Feeding 6-mm length pellets decreased feed per body-weight gain compared to 3-mm length pellets. During the finisher (d 22 to 42) and whole grow-out (d 10 to 42) periods, while different pellet lengths had no effect on feed per body-weight gain values at 3-mm pellet diameter, increasing the pellet length decreased feed per body-weight gain at 4.76-mm pellet diameter. 6. Increasing pellet diameter and pellet length reduced the relative length of duodenum. Birds given 3-mm diameter pellets had heavier proventriculus compared to

  4. The interaction of reaction-bonded silicon carbide and inconel 600 with a nickel-based brazing alloy

    Science.gov (United States)

    McDermid, J. R.; Pugh, M. D.; Drew, R. A. L.

    1989-09-01

    The objective of the present research was to join reaction-bonded silicon carbide (RBSC) to INCONEL 600 (a nickel-based superalloy) for use in advanced heat engine applications using either direct brazing or composite interlayer joining. Direct brazing experiments employed American Welding Society (AWS) BNi-5, a commercial nickel-based brazing alloy, as a filler material; composite interlayers consisted of intimate mixtures of α-SiC and BNi-5 powders. Both methods resulted in the liquid filler metal forming a Ni-Si liquid with the free Si in the RBSC, which, in turn, reacted vigorously with the SiC component of the RBSC to form low melting point constituents in both starting materials and Cr carbides at the metal-ceramic interface. Using solution thermodynamics, it was shown that a Ni-Si liquid of greater than 60 at. pct Ni will decompose a-SiC at the experimental brazing temperature of 1200 ‡C; these calculations are consistent with the experimentally observed composition profiles and reaction morphology within the ceramic. It was concluded that the joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is not feasible due to the inevitability of the filler metal reacting with the ceramic, degrading the high-temperature properties of the base materials.

  5. Bond-based linear indices of the non-stochastic and stochastic edge-adjacency matrix. 1. Theory and modeling of ChemPhys properties of organic molecules.

    Science.gov (United States)

    Marrero-Ponce, Yovani; Martínez-Albelo, Eugenio R; Casañola-Martín, Gerardo M; Castillo-Garit, Juan A; Echevería-Díaz, Yunaimy; Zaldivar, Vicente Romero; Tygat, Jan; Borges, José E Rodriguez; García-Domenech, Ramón; Torrens, Francisco; Pérez-Giménez, Facundo

    2010-11-01

    Novel bond-level molecular descriptors are proposed, based on linear maps similar to the ones defined in algebra theory. The kth edge-adjacency matrix (E(k)) denotes the matrix of bond linear indices (non-stochastic) with regard to canonical basis set. The kth stochastic edge-adjacency matrix, ES(k), is here proposed as a new molecular representation easily calculated from E(k). Then, the kth stochastic bond linear indices are calculated using ES(k) as operators of linear transformations. In both cases, the bond-type formalism is developed. The kth non-stochastic and stochastic total linear indices are calculated by adding the kth non-stochastic and stochastic bond linear indices, respectively, of all bonds in molecule. First, the new bond-based molecular descriptors (MDs) are tested for suitability, for the QSPRs, by analyzing regressions of novel indices for selected physicochemical properties of octane isomers (first round). General performance of the new descriptors in this QSPR studies is evaluated with regard to the well-known sets of 2D/3D MDs. From the analysis, we can conclude that the non-stochastic and stochastic bond-based linear indices have an overall good modeling capability proving their usefulness in QSPR studies. Later, the novel bond-level MDs are also used for the description and prediction of the boiling point of 28 alkyl-alcohols (second round), and to the modeling of the specific rate constant (log k), partition coefficient (log P), as well as the antibacterial activity of 34 derivatives of 2-furylethylenes (third round). The comparison with other approaches (edge- and vertices-based connectivity indices, total and local spectral moments, and quantum chemical descriptors as well as E-state/biomolecular encounter parameters) exposes a good behavior of our method in this QSPR studies. Finally, the approach described in this study appears to be a very promising structural invariant, useful not only for QSPR studies but also for similarity

  6. Weight, length and head circumference standards based on a population of Danish newborn boys and girls in gestational weeks 25 to 43

    DEFF Research Database (Denmark)

    Ulrich, M; Høst, A; Kamper, J

    1997-01-01

    Growth standards of birth weight, birth length and birth head circumference were constructed based on a population of Danish newborn boys and girls in gestational weeks twenty-five to forty-three. Study populations were residents of the municipality of Odense for later gestational ages and reside......Growth standards of birth weight, birth length and birth head circumference were constructed based on a population of Danish newborn boys and girls in gestational weeks twenty-five to forty-three. Study populations were residents of the municipality of Odense for later gestational ages...... and residents of the county of Funen for early gestational ages. Strict selection criteria were employed....

  7. Ultrafast OH-stretching frequency shifts of hydrogen- bonded 2-naphthol photoacid-base complexes in solution

    Directory of Open Access Journals (Sweden)

    Batista VictorS.

    2013-03-01

    Full Text Available We characterize the transient solvent-dependent OH-stretching frequency shifts of photoacid 2-naphthol hydrogen-bonded with CH3CN in the S0- and S1-states using a combined experimental and theoretical approach, and disentangle specific hydrogen-bonding contributions from nonspecific dielectric response.

  8. Probing the structural dependence of carbon space lengths of poly(N-hydroxyalkyl acrylamide)-based brushes on antifouling performance.

    Science.gov (United States)

    Yang, Jintao; Zhang, Mingzhen; Chen, Hong; Chang, Yung; Chen, Zhan; Zheng, Jie

    2014-08-11

    Numerous biocompatible antifouling polymers have been developed for a wide variety of fundamental and practical applications in drug delivery, biosensors, marine coatings, and many other areas. Several antifouling mechanisms have been proposed, but the exact relationship among molecular structure, surface hydration property, and antifouling performance of antifouling polymers still remains elusive. Here this work strives to provide a better understanding of the structure-property relationship of poly(N-hydroxyalkyl acrylamide)-based materials. We have designed, synthesized, and characterized a series of polyHAAA brushes of various carbon spacer lengths (CSLs), that is, poly(N-hydroxymethyl acrylamide) (polyHMAA), poly(N-(2-hydroxyethyl)acrylamide) (polyHEAA), poly(N-(3-hydroxypropyl)acrylamide) (polyHPAA), and poly(N-(5-hydroxypentyl)acrylamide) (polyHPenAA), to study the structural dependence of CSLs on their antifouling performance. HMAA, HEAA, HPAA, and HPenAA monomers contained one, two, three, and five methylene groups between hydroxyl and amide groups, while the other groups in polymer backbones were the same as each other. The relation of such small structural differences of polymer brushes to their surface hydration and antifouling performance was studied by combined experimental and computational methods including surface plasmon resonance sensors, sum frequency generation (SFG) vibrational spectroscopy, cell adhesion assay, and molecular simulations. Antifouling results showed that all polyHAAA-based brushes were highly surface resistant to protein adsorption from single protein solutions, undiluted blood serum and plasma, as well as cell adhesion up to 7 days. In particular, polyHMAA and polyHEAA with the shorter CSLs exhibited higher surface hydration and better antifouling ability than polyHPMA and polyHPenAA. SFG and molecular simulations further revealed that the variation of CSLs changed the ratio of hydrophobicity/hydrophilicity of polymers

  9. Substituent effif ects on hydrogen bonding in Watson-Crick base pairs. A theoretical study

    NARCIS (Netherlands)

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

    2005-01-01

    We have theoretically analyzed Watson-Crick AT and GC base pairs in which purine C8 and/or pyrimidine C6 positions carry a substituent X = H, F, Cl or Br, using the generalized gradient approximation (GGA) of density functional theory at BP86/TZ2P. The purpose is to study the effects on structure

  10. 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

  11. 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

  12. 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

  13. 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.

  14. Short and long term behaviour of externally bonded fibre reinforced polymer laminates with bio-based resins for flexural strengthening of concrete beams

    Science.gov (United States)

    McSwiggan, Ciaran

    The use of bio-based resins in composites for construction is emerging as a way to reduce of embodied energy produced by a structural system. In this study, two types of bio-based resins were explored: an epoxidized pine oil resin blend (EP) and a furfuryl alcohol resin (FA) derived from corn cobs and sugar cane. Nine large-scale reinforced concrete beams strengthened using externally bonded carbon and glass fibre reinforced bio-based polymer (CFRP and GFRP) sheets were tested. The EP resin resulted in a comparable bond strength to conventional epoxy (E) when used in wet layup, with a 7% higher strength for CFRP. The FA resin, on the other hand, resulted in a very weak bond, likely due to concrete alkalinity affecting curing. However, when FA resin was used to produce prefabricated cured CFRP plates which were then bonded to concrete using conventional epoxy paste, it showed an excellent bond strength. The beams achieved an increase in peak load ranging from 18-54% and a 9-46% increase in yielding load, depending on the number of FRP layers and type of fibres and resin. Additionally, 137 concrete prisms with a mid-span half-depth saw cut were used to test CFRP bond durability, and 195 CFRP coupons were used to examine tensile strength durability. Specimens were conditioned in a 3.5% saline solution at 23, 40 or 50°C, for up to 240 days. Reductions in bond strength did not exceed 15%. Bond failure of EP was adhesive with traces of cement paste on CFRP, whereas that of FA was cohesive with a thicker layer of concrete on CFRP, suggesting that the bond between FA and epoxy paste is excellent. EP tension coupons had similar strength and modulus to E resin, whereas FA coupons had a 9% lower strength and 14% higher modulus. After 240 days of exposure, maximum reductions in tensile strength were 8, 19 and 10% for EP, FA and E resins, respectively. Analysis of Variance (ANOVA) was also performed to assess the significance of the reductions observed. High degrees of

  15. Shear force bond analysis between acrylic resin bases and retention framework (open- and mesh-type)

    Science.gov (United States)

    Royhan, A.; Indrasari, M.; Masulili, C.

    2017-08-01

    Occlusions between teeth and the activity of the muscles around an artificial tooth during mastication create a force on dentures. This force causes friction between acrylic resin bases and retention frameworks that can lead to the complete loss of the acrylic resin base from the framework. The purpose of this study was to analyze the design of retention frameworks and determine which ones have a better resistance to shear forces in order to prevent the loss of heat cured acrylic resin base (HCARB). Six samples each of open-and mesh-type retention frameworks, both types made of Co-Cr material, and HCARB, were shear tested by means of a universal testing machine. The average shear force required to release the HCARB for mesh-type retention frameworks was 28.84 kgf, and the average for the open-type was 26.52 kgf. There was no significant difference between the shear forces required to remove HCARB from open- and mesh-type retention frameworks.

  16. Evaluation of shear bond strength of metal bracket to enamel after application of primers over bracket base-an in vitro study

    Directory of Open Access Journals (Sweden)

    Firuzbakht MM

    2011-04-01

    Full Text Available "nBackground and Aims: The aim of this study was to evaluate the effect of application of two types of primers over bracket bases on the shear bond strength (SBS and mode of bond failure."nMaterials and Methods: In this study, 75 human premolar teeth were divided into three equal groups. In group 1 (control, after surface preparation of enamel by conventional method (acid etching+primer brackets were bonded with Transbond XT composite. In group 2 (TX, brackets were bonded to enamel same as the first group but Transbond XT primer were used on bracket bases before placement of composite. In group 3 (PL, Transbond plus primer was applied on bracket bases before placement of composite. After 24 h, the SBS test was performed by universal testing machine at crosshead speed of 0.5 mm/min. Then, adhesive remnant index (ARI scores and percentage of cohesive fracture were determined using stereomicroscopy. SBS data were analyzed by one-way ANOVA and Duncan tests. Kruskal-Wallis and Mann-Whitney tests were used to analyze ARI and cohesive fracture results."nResults: There was significant difference in SBS values among the groups (P<0.001. The highest SBS was shown in TX group and the lowest was seen in PL group. There was no significant difference between control and TX groups in ARI scores (P=0.199. No significant difference was found in cohesive fracture values between the groups (P=0.093. Both the control and TX groups showed significant difference in ARI scores and cohesive fracture compared with the PL group in all of the comparisons (P<0.001."nConclusion: Application of Transbond XT primer over bracket base affects the bond strength and failure mode. Transbond XT primer increased the bond strength but Transbond plus primer decreased it.

  17. 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

  18. Evaluation of predicted Medfly (Ceratitis capitata quarantine length in the United States utilizing degree-day and agent-based models [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Travis Collier

    2017-10-01

    Full Text Available Invasions by pest insects pose a significant threat to agriculture worldwide. In the case of Ceratitis capitata incursions on the US mainland, where it is not officially established, repeated detections are followed by quarantines and treatments to eliminate the invading population. However, it is difficult to accurately set quarantine duration because non-detection may not mean the pest is eliminated. Most programs extend quarantine lengths past the last fly detection by calculating the amount of time required for 3 generations to elapse under a thermal unit accumulation development model (“degree day”. A newer approach is to use an Agent-Based Simulation (ABS to explicitly simulate population demographics and elimination. Here, predicted quarantine lengths for 11 sites in the continental United States are evaluated using both approaches. Results indicate a strong seasonality in quarantine length, with longer predictions in the second half of the year compared with the first; this pattern is more extreme in degree day predictions compared with ABS. Geographically, quarantine lengths increased with latitude, though this was less pronounced under the ABS. Variation in quarantine lengths for particular times and places was dramatically larger for degree day than ABS, generally spiking in the middle of the year for degree day and peaking in second half of the year for ABS. Analysis of 34 C. capitata quarantines from 1975 to 2017 in California shows that, for all but two, quarantines were started in the second half of the year, when degree day quarantine lengths are longest and have the highest uncertainty. For a set of hypothetical outbreaks based on these historical quarantines, the ABS produced significantly shorter quarantines than degree day calculations. Overall, ABS quarantine lengths were more consistent than degree day predictions, avoided unrealistically long values, and captured effects of rare events such as cold snaps.

  19. Nanofiber-bonded cloth materials based on poly-3-hydroxybutyrate with antibacterial properties for medical purposes

    Science.gov (United States)

    Tyubaeva, P. M.; Olkhov, A. A.; Karpova, S. G.; Iordansky, A. L.; Popov, A. A.

    2017-12-01

    Different transdermal systems based on solid polymer matrices or gels containing functional substances with antiseptic (antibacterial) properties have application to the therapy of many infectious diseases and cancer. Today the most promising type of matrices with antiseptic characteristics are the nano- and microfiber nonwoven materials. Fibers on the biopolymer (poly(3-hydroxybutyrate)) basis were obtained using the electrospinning method. In the present work, the effects of iron (III) complex with tetraphenylporphyrin and its influence on bactericidal and antibacterial properties of the ultrathin PHB fibers were investigated.

  20. Effects of Piezoelectric (PZT) Sensor Bonding and the Characteristics of the Host Structure on Impedance Based Structural Health Monitoring

    Science.gov (United States)

    Jalloh, Abdul

    2005-01-01

    This study was conducted to investigate the effects of certain factors on the impedance signal in structural health monitoring. These factors were: the quality of the bond between the sensor and the host structure, and the characteristics of the host structure, such as geometry, mass, and material properties. This work was carried out to answer a set of questions, related to these factors, that were developed by the project team. The project team was comprised of Dr. Doug Ramers and Dr. Abdul Jalloh of the Summer Faculty Fellowship Program, Mr. Arnaldo Colon- Perez, a student intern from the University of Puerto Rico of Turabo, and Mr. John Lassiter and Mr. Bob Engberg of the Structural and Dynamics Test Group at NASA Marshall Space Flight Center (MSFC). This study was based on a review of the literature on structural health monitoring to investigate the factors referred to above because there was not enough time to plan and conduct the appropriate tests at MSFC during the tenure of the Summer Faculty Fellowship Program project members. The surveyed literature documents works on structural health monitoring that were based on laboratory tests that were conducted using bolted trusses and other civil engineering type structures for the most part. These are not the typical types of structures used in designing and building NASA s space vehicles and systems. It was therefore recommended that tests be conducted using NASA type structures, such as pressure vessels, to validate the observations made in this report.

  1. 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.

  2. 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.

  3. Patient-Specific Instruments Based on Knee Joint Computed Tomography and Full-Length Lower Extremity Radiography in Total Knee Replacement

    Directory of Open Access Journals (Sweden)

    Hua Tian

    2018-01-01

    Conclusions: The use of PSIs based on knee joint CT and standing full-length lower extremity radiography in TKR resulted in acceptable alignment compared with the use of conventional instruments, although the marginal advantage was not statistically different. Surgical time and clinical results were also similar between the two groups. However, the PSI group had less postoperative drainage.

  4. The Influence of the Coating Deposition Process on the Interdiffusion Behavior Between Nickel-Based Superalloys and MCrAlY Bond Coats

    Science.gov (United States)

    Elsaß, M.; Frommherz, M.; Oechsner, M.

    2018-02-01

    In this work, interdiffusion between two nickel-based superalloys and two MCrAlY bond coats is investigated. The MCrAlY bond coats were applied using two different spraying processes, high velocity oxygen fuel spraying (HVOF) and low-pressure plasma spraying. Of primary interest is the evolution of Kirkendall porosity, which can form at the interface between substrate and bond coat and depends largely on the chemical compositions of the coating and substrate. Experimental evidence further suggested that the formation of Kirkendall porosity depends on the coating deposition process. Formation of porosity at the interface causes a degradation of the bonding strength between substrate and coating. After coating deposition, the samples were annealed at 1050 °C for up to 2000 h. Microstructural and compositional analyses were performed to determine and evaluate the Kirkendall porosity. The results reveal a strong influence of both the coating deposition process and the chemical compositions. The amount of Kirkendall porosity formed, as well as the location of appearance, is largely influenced by the coating deposition process. In general, samples with bond coats applied by means of HVOF show accelerated element diffusion. It is hypothesized that recrystallization of the substrate material is a main root cause for these observations.

  5. Study of chemical bonding in the interhalogen complexes based on density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Poleshchuk, O. Kh., E-mail: poleshch@tspu.edu.ru [National Research Tomsk Polytechnic University (Russian Federation); Fateev, A. V.; Yarkova, A. G. [Tomsk State Pedagogical University (Russian Federation); Ermakhanov, M. N.; Saidakhmetov, P. A. [M. Auezov South Kazakhstan State University (Kazakhstan)

    2016-12-15

    The density functional theory analysis was used for a number XYL complexes (XY is a dihalogen molecule and L is a Lewis base), formed between molecules I{sub 2}, ICl, IBr and pyridine. The calculated geometrical parameters, IR spectra and nuclear quadrupole interaction constants of iodine are consistent with the data of microwave spectroscopy and nuclear quadrupole resonance. The good correlation between the experimental and calculated binding energies of the inner electrons of iodine, chlorine and nitrogen atoms were found with the calculation using both Gaussian and Slater functions. The comparison of experimental and calculated changes in the electron density on the atoms upon complex formation suggested the choice of scheme for calculating the effective charge on the atoms, which allow us to interpret the experimental spectra. It is shown that the use of both calculated schemes allows us to predict the enthalpy of complex formation in close agreement with the experimental values. The energy analysis shows that in the complexes the electrostatic binding energy dominates that of covalent binding.

  6. Psychometric Validation of the Parental Bonding Instrument in a UK Population–Based Sample Role of Gender and Association With Mental Health in Mid-Late Life

    NARCIS (Netherlands)

    M.K. Xu (Kate); A. J. S. Morin (Alexandre); H. W. Marsh (Herbert); M. Richards (Martin); P. B. Jones (Peter)

    2016-01-01

    markdownabstractThe factorial structure of the Parental Bonding Instrument (PBI) has been frequently studied in diverse samples but no study has examined its psychometric properties from large, population-based samples. In particular, important questions have not been addressed such as the

  7. 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

  8. The Influence of Activity-Based Funding on Treatment Intensity and Length of Stay of Geriatric Rehabilitation Patients.

    Science.gov (United States)

    Bouwstra, Hylco; Wattel, Lizette M; de Groot, Aafke J; Smalbrugge, Martin; Hertogh, Cees M

    2017-06-01

    Little is known about the impact of activity-based funding (ABF) to increase treatment intensity and decrease length of stay (LOS) of inpatient geriatric patients. In January 2014, ABF was implemented in The Netherlands with the aim to increase treatment intensity and shorten LOS in geriatric rehabilitation (GR). To describe the influence of ABF on treatment intensity and LOS of inpatient GR patients before and after ABF was implemented. Population-based, retrospective cohort study. Thirty nursing homes providing inpatient GR across The Netherlands. Digital medical records of patients who had received inpatient GR in Dutch nursing homes across The Netherlands were studied between January 1, 2013 and March 14, 2016. We calculated the mean treatment intensity in hours per week and median LOS in days in 3 cohorts according to the year of admittance. In addition, a historical representative cohort of GR patients who were admitted in 2007 was studied that represented the situation before the ABF reform was announced (eg, funding with a fixed price per day). In 2013, the funding with a fixed price per day was still in use but with compulsory ABF registration. In 2014 and 2015, the ABF was fully implemented. Statistical differences in treatment intensity and LOS were calculated between patients admitted in 2007 and 2013, 2013 and 2014, and 2013 and 2015. Statistical significance was set at a P value of <.02 (Bonferroni correction P = .05/3). Discharge destinations of patients discharged from March 1, 2015 to January 1, 2016 could be obtained and compared with 2007. The treatment intensity and LOS of 16,823 GR patients could be obtained and compared with the historical cohort from 2007 (n = 2950). Patients who were admitted in the year 2013 received higher treatment intensities and had the same median LOS compared with 2007. After the implementation of ABF in January 2014, the mean treatment intensity increased significantly by 37% (3.8 hours/week in 2013, 4.7

  9. Typing of Human Mycobacterium avium Isolates in Italy by IS1245-Based Restriction Fragment Length Polymorphism Analysis

    Science.gov (United States)

    Lari, Nicoletta; Cavallini, Michela; Rindi, Laura; Iona, Elisabetta; Fattorini, Lanfranco; Garzelli, Carlo

    1998-01-01

    All but 2 of 63 Mycobacterium avium isolates from distinct geographic areas of Italy exhibited markedly polymorphic, multibanded IS1245 restriction fragment length polymorphism (RFLP) patterns; 2 isolates showed the low-number banding pattern typical of bird isolates. By computer analysis, 41 distinct IS1245 patterns and 10 clusters of essentially identical strains were detected; 40% of the 63 isolates showed genetic relatedness, suggesting the existence of a predominant AIDS-associated IS1245 RFLP pattern. PMID:9817900

  10. Dynamic response of a carbon nanotube-based rotary nano device with different carbon-hydrogen bonding layout

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Hang [College of Water Resources and Architectural Engineering, Northwest A& F University, Yangling 712100 (China); Cai, Kun, E-mail: caikun1978@163.com [College of Water Resources and Architectural Engineering, Northwest A& F University, Yangling 712100 (China); Wan, Jing [College of Water Resources and Architectural Engineering, Northwest A& F University, Yangling 712100 (China); Gao, Zhaoliang, E-mail: coopcg@163.com [Institute of Soil and Water Conservation, Northwest A& F University, Yangling, 712100 (China); Chen, Zhen [State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, Dalian 116024 (China)

    2016-03-01

    Graphical abstract: - Highlights: • The rotational transmission performance of a rotational transmission system (RTS) with different types of C−H bonding layouts on the edge of motor and rotor is investigated using MD simulation method. • The L–J interaction between covalently bonded hydrogen atoms and sp1 carbon atoms is too weak to support a stable rotational transmission when only the motor or rotor has bonded hydrogen atoms. • When both the motor and rotor have the same C−H bonding layout on their adjacent ends, a stable output rotational speed of rotor can be obtained. • A low input rotational speed (e.g., 100 GHz) would lead to a synchronous rotational transmission if the system has (+0.5H) C−H bonding layout. - Abstract: In a nano rotational transmission system (RTS) which consists of a single walled carbon nanotube (SWCNT) as the motor and a coaxially arranged double walled carbon nanotube (DWCNT) as a bearing, the interaction between the motor and the rotor in bearing, which has great effects on the response of the RTS, is determined by their adjacent edges. Using molecular dynamics (MD) simulation, the interaction is analyzed when the adjacent edges have different carbon-hydrogen (C−H) bonding layouts. In the computational models, the rotor in bearing and the motor with a specific input rotational speed are made from the same armchair SWCNT. Simulation results demonstrate that a perfect rotational transmission could happen when the motor and rotor have the same C−H bonding layout on their adjacent ends. If only half or less of the carbon atoms on the adjacent ends are bonded with hydrogen atoms, the strong attraction between the lower speed (100 GHz) motor and rotor leads to a synchronous rotational transmission. If only the motor or the rotor has C−H bonds on their adjacent ends, no rotational transmission happens due to weak interaction between the bonded hydrogen atoms on one end with the sp{sup 1} bonded carbon atoms on the other

  11. Generation of a reliable full-length cDNA of infectiousTembusu virus using a PCR-based protocol.

    Science.gov (United States)

    Liang, Te; Liu, Xiaoxiao; Cui, Shulin; Qu, Shenghua; Wang, Dan; Liu, Ning; Wang, Fumin; Ning, Kang; Zhang, Bing; Zhang, Dabing

    2016-02-02

    Full-length cDNA of Tembusu virus (TMUV) cloned in a plasmid has been found instable in bacterial hosts. Using a PCR-based protocol, we generated a stable full-length cDNA of TMUV. Different cDNA fragments of TMUV were amplified by reverse transcription (RT)-PCR, and cloned into plasmids. Fragmented cDNAs were amplified and assembled by fusion PCR to produce a full-length cDNA using the recombinant plasmids as templates. Subsequently, a full-length RNA was transcribed from the full-length cDNA in vitro and transfected into BHK-21 cells; infectious viral particles were rescued successfully. Following several passages in BKH-21 cells, the rescued virus was compared with the parental virus by genetic marker checks, growth curve determinations and animal experiments. These assays clearly demonstrated the genetic and biological stabilities of the rescued virus. The present work will be useful for future investigations on the molecular mechanisms involved in replication and pathogenesis of TMUV. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. 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.

  13. Microstructure of bonding zones in laser-clad Ni-alloy-based composite coatings reinforced with various ceramic powders

    International Nuclear Information System (INIS)

    Pei, Y.T.; Ouyang, J.H.; Lei, T.C.

    1996-01-01

    Microstructure of the bonding zones (BZs) between laser-clad Ni-alloy-based composite coatings and steel substrates was studied by means of scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. Observations indicate that for pure Ni-alloy coating the laser parameters selected for good interface fusion have no effect on the microstructure of the BZ except for its thickness. However, the addition of ceramic particles (TiN, SiC, or ZrO 2 ) to the Ni alloy varies the compositional or constitutional undercooling of the melt near the solid/liquid interface and consequently leads to the observed changes of microstructure of the BZs. For TiN/Ni-alloy coating the morphology of γ-Ni solid solution in the BZ changes from dendritic to planar form with increasing scanning speed. A colony structure of eutectic is found in the BZ of SiC/Ni-alloy coating in which complete dissolution of SiC particles takes place during laser cladding. The immiscible melting of ZrO 2 and Ni-alloy powders induces the stratification of ZrO 2 /Ni-alloy coating which consists of a pure ZrO 2 layer fin the upper region and a BZ composed mainly of γ-Ni dendrites adjacent to the substrate. All the BZs studied in this investigation have good metallurgical characteristics between the coatings and the substrates

  14. Apatite and sodalite based glass-bonded waste forms for immobilization of 129I and mixed halide radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Goel, Ashutosh [Rutgers Univ., New Brunswick, NJ (United States); McCloy, John S. [Washington State Univ., Pullman, WA (United States); Riley, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Matyas, Josef [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-12-30

    The goal of the project was to utilize the knowledge accumulated by the team, in working with minerals for chloride wastes and biological apatites, toward the development of advanced waste forms for immobilizing 129I and mixed-halide wastes. Based on our knowledge, experience, and thorough literature review, we had selected two minerals with different crystal structures and potential for high chemical durability, sodalite and CaP/PbV-apatite, to form the basis of this project. The focus of the proposed effort was towards: (i) low temperature synthesis of proposed minerals (iodine containing sodalite and apatite) leading to the development of monolithic waste forms, (ii) development of a fundamental understanding of the atomic-scale to meso-scale mechanisms of radionuclide incorporation in them, and (iii) understanding of the mechanism of their chemical corrosion, alteration mechanism, and rates. The proposed work was divided into four broad sections. deliverables. 1. Synthesis of materials 2. Materials structural and thermal characterization 3. Design of glass compositions and synthesis glass-bonded minerals, and 4. Chemical durability testing of materials.

  15. A piezoelectric micro generator worked at low frequency and high acceleration based on PZT and phosphor bronze bonding.

    Science.gov (United States)

    Tang, Gang; Yang, Bin; Hou, Cheng; Li, Guimiao; Liu, Jingquan; Chen, Xiang; Yang, Chunsheng

    2016-12-08

    Recently, piezoelectric energy harvesters (PEHs) have been paid a lot of attention by many researchers to convert mechanical energy into electrical and low level vibration. Currently, most of PEHs worked under high frequency and low level vibration. In this paper, we propose a micro cantilever generator based on the bonding of bulk PZT wafer and phosphor bronze, which is fabricated by MEMS technology, such as mechanical chemical thinning and etching. The experimental results show that the open-circuit output voltage, output power and power density of this fabricated prototype are 35 V, 321 μW and 8664 μW cm -3 at the resonant frequency of 100.8 Hz, respectively, when it matches an optimal loading resistance of 140 kΩ under the excitation of 3.0 g acceleration. The fabricated micro generator can obtain the open-circuit stable output voltage of 61.2 V when the vibration acceleration arrives at 7.0 g. Meanwhile, when this device is pasted on the vibrating vacuum pump, the output voltage is about 11 V. It demonstrates that this novel proposed device can scavenge high vibration level energy at low frequency for powering the inertial sensors in internet of things application.

  16. 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 ...

  17. 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

  18. Density functional theory based-study of 5-fluorouracil adsorption on β-cristobalite (1 1 1) hydroxylated surface: The importance of H-bonding interactions

    Energy Technology Data Exchange (ETDEWEB)

    Simonetti, S., E-mail: ssimonet@uns.edu.ar [Universidad Nacional del Sur (UNS)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca (Argentina); Universidad Tecnológica Nacional (UTN), Bahía Blanca (Argentina); Compañy, A. Díaz [Comisión de Investigaciones Científicas (CIC), Buenos Aires (Argentina); Pronsato, E.; Juan, A.; Brizuela, G. [Universidad Nacional del Sur (UNS)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca (Argentina); Lam, A. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana (Cuba)

    2015-12-30

    Graphical abstract: - Highlights: • Favorable energies results in optimum four adsorption geometries. • Silanols are partially weakening and establish H-bonds with polar groups of 5-FU drug. • Dispersion forces approach the 5-FU molecule toward the surface. • Electron exchange is presented after adsorption. • H-bonds stabilize the molecule playing significant role in the adsorption mechanism. - Abstract: Silica-based mesoporous materials have been recently proposed as an efficient support for the controlled release of a popular anticancer drug, 5-fluorouracil (5-FU). Although the relevance of this topic, the atomistic details about the specific surface-drug interactions and the energy of adsorption are almost unknown. In this work, theoretical calculations using the Vienna Ab-initio Simulation Package (VASP) applying Grimme's—D2 correction were performed to elucidate the drug–silica interactions and the host properties that control 5-FU drug adsorption on β-cristobalite (1 1 1) hydroxylated surface. This study shows that hydrogen bonding, electron exchange, and dispersion forces are mainly involved to perform the 5-FU adsorption onto silica. This phenomenon, revealed by favorable energies, results in optimum four adsorption geometries that can be adopted for 5-FU on the hydroxylated silica surface. Silanols are weakening in response to the molecule approach and establish H-bonds with polar groups of 5-FU drug. The final geometry of 5-FU adopted on hydroxylated silica surface is the results of H-bonding interactions which stabilize and fix the molecule to the surface and dispersion forces which approach it toward silica (1 1 1) plane. The level of hydroxylation of the SiO{sub 2} (1 1 1) surface is reflected by the elevated number of hydrogen bonds that play a significant role in the adsorption mechanisms.

  19. Estimation of radiative forcing and chore length of shallow convective clouds (SCC) based on broadband pyranometer measurement network

    Science.gov (United States)

    Shi, H.

    2017-12-01

    We presented a method to identify and calculate cloud radiative forcing (CRF) and horizontal chore length (L) of shallow convective clouds (SCC) using a network of 9 broadband pyranometers. The analyzing data was collected from the SCC campaign during two years summers (2015 2016) at Baiqi site over Inner Mongolia grassland. The network of pyranometers was operated across a spatial domain covering 42.16-42.30° N and 114.83-114.98° E. The SCC detection method was verified by observer reports and cameras, which showed that the detection method and human observations were in agreement about 75 %. The differences between the SCC detection method and human observations can be responsible for following factors: 1) small or dissipating clouds can be neglected for the value of 1 min of temporal resolution of pyranometer; 2) human observation recorded weather conditions four times every day; 3) SCC was indistinguishable from coexistence of SCC and Cirrus (Ci); 4) the SCC detection method is weighted toward clouds crossing the sun's path, while the human observer can view clouds over the entire sky. The deviation of L can be attributed to two factors: 1) the accuracy of wind speed at height of SCC and the ratio of horizontal and vertical length play a key role in determine values of L; 2) the effect of variance of solar zenith angle can be negligible. The downwelling shortwave CRF of SCC was -134.1 Wm-2. The average value of L of SCC was 1129 m. Besides, the distribution of normalized cloud chore length agreed well with power-law fit.

  20. BiOBr@SiO2 flower-like nanospheres chemically-bonded on cement-based materials for photocatalysis

    Science.gov (United States)

    Wang, Dan; Hou, Pengkun; Yang, Ping; Cheng, Xin

    2018-02-01

    Endowment of photocatalytic property on the surface of concrete structure can contribute to the self-cleaning of the structure and purification of the polluted environment. We developed a nano-structured BiOBr@SiO2 photocatalyst and innovatively used for surface-treatment of cement-based materials with the hope of attaining the photocatalytic property in visible-light region and surface modification/densification performances. The SiO2 layer on the flower-like BiOBr@SiO2 helps to maintain a stable distribution of the photocatalyst, as well as achieving a chemical bonding between the coating and the cement matrix. Results showed that the color fading rate of during the degradation of Rhodamine B dye of the BiOBr-cem sample is 2 times higher compared with the commonly studied C, N-TiO2-cem sample. The photo-degradation rates of samples BiOBr-cem and BiOBr@SiO2-cem are 93 and 81% within 150 min, respectively, while sample BiOBr@SiO2-cem reveals a denser and smoother surface after curing for 28 days and pore-filling effect at size within 0.01-0.2 μm when compared with untreated samples. Moreover, additional C-S-H gel can be formed due to the pozzolanic reaction between BiOBr@SiO2 and the hardened cement matrix. Both advantages of the BiOBr@SiO2 favor its application for surface-treatment of hardened cement-based material to acquire an improved surface quality, as well as durable photocatalytic functionality.

  1. Lubricating Properties of Ceramic-Bonded Calcium Fluoride Coatings on Nickel-Base Alloys from 75 to 1900 deg F

    Science.gov (United States)

    Sliney, Harold E.

    1962-01-01

    The endurance life and the friction coefficient of ceramic-bonded calcium fluoride (CaF2) coatings on nickel-base alloys were determined at temperatures from 75 F to 1900 F. The specimen configuration consisted of a hemispherical rider (3/16-in. rad.) sliding against the flat surface of a rotating disk. Increasing the ambient temperature (up to 1500 F) or the sliding velocity generally reduced the friction coefficient and improved coating life. Base-metal selection was critical above 1500 F. For instance, cast Inconel sliding against coated Inconel X was lubricated effectively to 1500 F, but at 1600 F severe blistering of the coatings occurred. However, good lubrication and adherence were obtained for Rene 41 sliding against coated Rene 41 at temperatures up to 1900 F; no blisters developed, coating wear life was fairly good, and the rider wear rate was significantly lower than for the unlubricated metals. Friction coefficients were 0.12 at 1500 F, 0.15 at 1700 F, and 0.17 at 1800 F and 1900 F. Because of its ready availability, Inconel X appears to be the preferred substrate alloy for applications in which the temperature does not exceed 1500 F. Rene 41 would have to be used in applications involving higher temperatures. Improved coating life was derived by either preoxidizing the substrate metals prior to the coating application or by applying a very thin (less than 0.0002 in.) burnished and sintered overlay to the surface of the coating. Preoxidation did not affect the friction coefficient. The overlay generally resulted in a higher friction coefficient than that obtained without the overlay. The combination of both modifications resulted in longer coating life and in friction coefficients intermediate between those obtained with either modification alone.

  2. PCR-based isolation and identification of full-length low-molecular-weight glutenin subunit genes in bread wheat (Triticum aestivum L.).

    Science.gov (United States)

    Zhang, Xiaofei; Liu, Dongcheng; Jiang, Wei; Guo, Xiaoli; Yang, Wenlong; Sun, Jiazhu; Ling, Hongqing; Zhang, Aimin

    2011-12-01

    Low-molecular-weight glutenin subunits (LMW-GSs) are encoded by a multi-gene family and are essential for determining the quality of wheat flour products, such as bread and noodles. However, the exact role or contribution of individual LMW-GS genes to wheat quality remains unclear. This is, at least in part, due to the difficulty in characterizing complete sequences of all LMW-GS gene family members in bread wheat. To identify full-length LMW-GS genes, a polymerase chain reaction (PCR)-based method was established, consisting of newly designed conserved primers and the previously developed LMW-GS gene molecular marker system. Using the PCR-based method, 17 LMW-GS genes were identified and characterized in Xiaoyan 54, of which 12 contained full-length sequences. Sequence alignments showed that 13 LMW-GS genes were identical to those found in Xiaoyan 54 using the genomic DNA library screening, and the other four full-length LMW-GS genes were first isolated from Xiaoyan 54. In Chinese Spring, 16 unique LMW-GS genes were isolated, and 13 of them contained full-length coding sequences. Additionally, 16 and 17 LMW-GS genes in Dongnong 101 and Lvhan 328 (chosen from the micro-core collections of Chinese germplasm), respectively, were also identified. Sequence alignments revealed that at least 15 LMW-GS genes were common in the four wheat varieties, and allelic variants of each gene shared high sequence identities (>95%) but exhibited length polymorphism in repetitive regions. This study provides a PCR-based method for efficiently identifying LMW-GS genes in bread wheat, which will improve the characterization of complex members of the LMW-GS gene family and facilitate the understanding of their contributions to wheat quality.

  3. Probing electron density of H-bonding between cation-anion of imidazolium-based ionic liquids with different anions by vibrational spectroscopy.

    Science.gov (United States)

    Gao, Yan; Zhang, Liqun; Wang, Yong; Li, Haoran

    2010-03-04

    Attenuated total reflection infrared spectroscopy and density functional theory calculation have been employed to study the spectral properties of imidazolium-based ionic liquids (ILs) with different anions. ILs based on 1-butyl-3-methylimidazolium cation with different anions, OH(-), CF(3)CO(2)(-), HSO(4)(-), H(2)PO(4)(-), Cl(-), PF(6)(-), and BF(4)(-), are investigated in the present work. It has been shown that the C(2)-H stretching vibration of the imidazolium ring is closely related to the electron density of H-bonding between the two closest cations and anions for pure ILs. The electron density of H-bonding between cation and anion with different anions decreases in the order [OH](-) > [H(2)PO(4)](-) > [HSO(4)](-) > [CF(3)CO(2)](-) > [Cl](-) > [BF(4)](-) > [PF(6)](-). For aqueous ILs, with increasing water content, the aromatic C-H stretching vibration of the imidazolium cation showed systematic blue-shifts. Especially for BmimOH, the nu(C(2))(-H) undergoes a drastic blue-shift by 58 cm(-1), suggesting that the formation of the strong hydrogen bonds O-H...O may greatly weaken the electron density of H-bonding between the cation and anion of ILs.

  4. Implementation and Evaluation of Web-Based Learning Activities on Bonding and the Structure of Matter for 10-th Grade Chemistry

    Science.gov (United States)

    Frailich, Marcel

    This study deals with the development, implementation, and evaluation of web-based activities associated with the topic of chemical bonding , as taught in 10th grade chemistry. A website was developed entitled: "Chemistry and the Chemical Industry in the Service of Mankind", its URL is: http://stwww.weizmann.ac.il/g-chem/learnchem (Kesner, Frailich, & Hofstein, 2003). The main goal of this study was to assess the educational effectiveness of website activities dealing with the chemical bonding concept. These activities include visualization tools, as well as topics relevant to daily life and industrial applications. The study investigated the effectiveness of a web-based learning environment regarding the understanding of chemical bonding concepts, students' perceptions of the classroom learning environment, their attitudes regarding the relevance of learning chemistry to everyday life, and their interest in chemistry studies. As mentioned before, in the present study we focused on activities (from the website), all of which deal with chemical bonding concept. The following are the reasons for the decision to focus on this topic: (1) Chemical bonding is a key concept that is taught in 10th grade chemistry in high school. It provides the basis for many other chemistry topics that are taught later, and (2) Chemical bonding is a difficult for students using existing tools (e. g., static models in books, ball-and- stick models), which are insufficient to demonstrate the abstract nature phenomena associated with this topic. The four activities developed for this study are (1) models of the atomic structure, (2) metals -- structure and properties, (3) ionic substances in everyday life and in industry, and (4) molecular substances -- structure, properties, and uses. The study analyzed both quantitative and qualitative research. The quantitative tools of the study included: A Semantic Differential questionnaire and a Chemistry Classroom Web-Based Learning Environment

  5. Effectiveness of different adhesive primers on the bond strength between an indirect composite resin and a base metal alloy.

    Science.gov (United States)

    Sarafianou, Aspasia; Seimenis, Ioannis; Papadopoulos, Triantafillos

    2008-05-01

    There is a need for achieving reliable chemical bond strength between veneering composites resins and casting alloys through the use of simplified procedures. The purpose of this study was to examine the shear bond strength of an indirect composite resin to a Ni-Cr alloy, using 4 primers and 2 airborne-particle-abrasion procedures. Fifty-six Ni-Cr (Heraenium NA) discs, 10 mm in diameter and 1.5 mm in height, were fabricated. Twenty-four discs were airborne-particle abraded with 50-microm Al2O3 particles, while another 24 were airborne-particle abraded with 250-microm Al2O3 particles. The following primers were applied on 6 discs of each airborne-particle-abrasion treatment group: Solidex Metal Photo Primer (MPP50, MPP250), Metal Primer II (MPII50, MPII250), SR Link (SRL50, SRL250), and Tender Bond (TB50, TB250). The Rocatec system was used on another 6 discs, airborne-particle abraded according to the manufacturer's recommendations, which served as the control group (R). Two more discs were airborne-particle abraded with 50-microm and 250-microm Al2O3 particles, respectively, to determine the Al content on their surfaces, without any bonding procedure. The indirect composite resin used was Sinfony. Specimens were thermally cycled (5 degrees C and 55 degrees C, 30-second dwell time, 5000 cycles) and tested in shear mode in a universal testing machine. The failure mode was determined with an optical microscope, and selected specimens were subjected to energy dispersive spectroscopy (EDS). Mean bond strength values were analyzed using 2-way ANOVA followed by Tukey's multiple comparison tests (alpha=.05) and compared to the control group using 1-way ANOVA followed by Tukey's multiple comparison tests (alpha=.05). The groups abraded with 50-microm particles exhibited significantly higher bond strength compared to the groups abraded with 250-microm particles. Group MPII50 exhibited the highest mean value (17.4 +/-2 MPa). Groups MPP50, MPP250, and TB50, TB250 showed

  6. Computational study of An-X bonding (An = Th, U; X = p-block-based ligands) in pyrrolic macrocycle-supported complexes from the quantum theory of atoms in molecules and bond energy decomposition analysis.

    Science.gov (United States)

    O'Brien, Kieran T P; Kaltsoyannis, Nikolas

    2017-01-17

    A systematic computational study of organoactinide complexes of the form [LAnX] n+ has been carried out using density functional theory, the quantum theory of atoms in molecules (QTAIM) and Ziegler-Rauk energy decomposition analysis (EDA) methods. The systems studied feature L = trans-calix[2]benzene[2]pyrrolide, An = Th(iv), Th(iii), U(iii) and X = BH 4 , BO 2 C 2 H 4 , Me, N(SiH 3 ) 2 , OPh, CH 3 , NH 2 , OH, F, SiH 3 , PH 2 , SH, Cl, CH 2 Ph, NHPh, OPh, SiH 2 Ph, PHPh 2 , SPh, CPh 3 , NPh 2 , OPh, SiPh 3 PPh 2 , SPh. The PBE0 hybrid functional proved most suitable for geometry optimisations based on comparisons with available experimental data. An-X bond critical point electron densities, energy densities and An-X delocalisation indices, calculated with the PBE functional at the PBE0 geometries, are correlated with An-X bond energies, enthalpies and with the terms in the EDA. Good correlations are found between energies and QTAIM metrics, particularly for the orbital interaction term, provided the X ligand is part of an isoelectronic series and the number of open shell electrons is low (i.e. for the present Th(iv) and Th(iii) systems).

  7. High-Temperature Oxidation-Resistant and Low Coefficient of Thermal Expansion NiAl-Base Bond Coat Developed for a Turbine Blade Application

    Science.gov (United States)

    2003-01-01

    Many critical gas turbine engine components are currently made from Ni-base superalloys that are coated with a thermal barrier coating (TBC). The TBC consists of a ZrO2-based top coat and a bond coat that is used to enhance the bonding between the superalloy substrate and the top coat. MCrAlY alloys (CoCrAlY and NiCrAlY) are currently used as bond coats and are chosen for their very good oxidation resistance. TBC life is frequently limited by the oxidation resistance of the bond coat, along with a thermal expansion mismatch between the metallic bond coat and the ceramic top coat. The aim of this investigation at the NASA Glenn Research Center was to develop a new longer life, higher temperature bond coat by improving both the oxidation resistance and the thermal expansion characteristics of the bond coat. Nickel aluminide (NiAl) has excellent high-temperature oxidation resistance and can sustain a protective Al2O3 scale to longer times and higher temperatures in comparison to MCrAlY alloys. Cryomilling of NiAl results in aluminum nitride (AlN) formation that reduces the coefficient of thermal expansion (CTE) of the alloy and enhances creep strength. Thus, additions of cryomilled NiAl-AlN to CoCrAlY were examined as a potential bond coat. In this work, the composite alloy was investigated as a stand-alone substrate to demonstrate its feasibility prior to actual use as a coating. About 85 percent of prealloyed NiAl and 15 percent of standard commercial CoCrAlY alloys were mixed and cryomilled in an attritor with stainless steel balls used as grinding media. The milling was carried out in the presence of liquid nitrogen. The milled powder was consolidated by hot extrusion or by hot isostatic pressing. From the consolidated material, oxidation coupons, four-point bend, CTE, and tensile specimens were machined. The CTE measurements were made between room temperature and 1000 C in an argon atmosphere. It is shown that the CTE of the NiAl-AlN-CoCrAlY composite bond coat

  8. Leg length, skull circumference, and the incidence of dementia in Latin America and China: A 10/66 population-based cohort study.

    Science.gov (United States)

    Prince, Martin J; Acosta, Daisy; Guerra, Mariella; Huang, Yueqin; Jimenez-Velazquez, Ivonne Z; Llibre Rodriguez, Juan J; Salas, Aquiles; Sosa, Ana Luisa; Dewey, Michael E; Guerchet, Maelenn M; Liu, Zhaorui; Llibre Guerra, Jorge J; Prina, A Matthew

    2018-01-01

    Adult leg length is influenced by nutrition in the first few years of life. Adult head circumference is an indicator of brain growth. Cross-sectional studies indicate inverse associations with dementia risk, but there have been few prospective studies. Population-based cohort studies in urban sites in Cuba, Dominican Republic Puerto Rico and Venezuela, and rural and urban sites in Peru, Mexico and China. Sociodemographic and risk factor questionnaires were administered to all participants, and anthropometric measures taken, with ascertainment of incident dementia, and mortality, three to five years later. Of the original at risk cohort of 13,587 persons aged 65 years and over, 2,443 (18.0%) were lost to follow-up; 10,540 persons with skull circumference assessments were followed up for 40,466 person years, and 10,400 with leg length assessments were followed up for 39,954 person years. There were 1,009 cases of incident dementia, and 1,605 dementia free deaths. The fixed effect pooled meta-analysed adjusted subhazard ratio (ASHR) for leg length (highest vs. lowest quarter) was 0.80 (95% CI, 0.66-0.97) and for skull circumference was 1.02 (95% CI, 0.84-1.25), with no heterogeneity of effect between sites (I2 = 0%). Leg length measurements tended to be shorter at follow-up, particularly for those with baseline cognitive impairment and dementia. However, leg length change was not associated with dementia incidence (ASHR, per cm 1.006, 95% CI 0.992-1.020), and the effect of leg length was little altered after adjusting for baseline frailty (ASHR 0.82, 95% CI 0.67-0.99). A priori hypotheses regarding effect modification by gender or educational level were not supported. However, the effect of skull circumference was modified by gender (M vs F ASHR 0.86, 95% CI 0.75-0.98), but in the opposite direction to that hypothesized with a greater protective effect of larger skull dimensions in men. Consistent findings across settings provide quite strong support for an

  9. Assessment of Possible Cycle Lengths for Fully-Ceramic Micro-Encapsulated Fuel-Based Light Water Reactor Concepts

    International Nuclear Information System (INIS)

    Sen, R. Sonat; Pope, Michael A.; Ougouag, Abderrafi M.; Pasamehmetoglu, Kemal O.

    2012-01-01

    The tri-isotropic (TRISO) fuel developed for High Temperature reactors is known for its extraordinary fission product retention capabilities (1). Recently, the possibility of extending the use of TRISO particle fuel to Light Water Reactor (LWR) technology, and perhaps other reactor concepts, has received significant attention (2). The Deep Burn project (3) currently focuses on once-through burning of transuranic fissile and fissionable isotopes (TRU) in LWRs. The fuel form for this purpose is called Fully-Ceramic Micro-encapsulated (FCM) fuel, a concept that borrows the TRISO fuel particle design from high temperature reactor technology, but uses SiC as a matrix material rather than graphite. In addition, FCM fuel may also use a cladding made of a variety of possible material, again including SiC as an admissible choice. The FCM fuel used in the Deep Burn (DB) project showed promising results in terms of fission product retention at high burnup values and during high-temperature transients. In the case of DB applications, the fuel loading within a TRISO particle is constituted entirely of fissile or fissionable isotopes. Consequently, the fuel was shown to be capable of achieving reasonable burnup levels and cycle lengths, especially in the case of mixed cores (with coexisting DB and regular LWR UO2 fuels). In contrast, as shown below, the use of UO2-only FCM fuel in a LWR results in considerably shorter cycle length when compared to current-generation ordinary LWR designs. Indeed, the constraint of limited space availability for heavy metal loading within the TRISO particles of FCM fuel and the constraint of low (i.e., below 20 w/0) 235U enrichment combine to result in shorter cycle lengths compared to ordinary LWRs if typical LWR power densities are also assumed and if typical TRISO particle dimensions and UO2 kernels are specified. The primary focus of this summary is on using TRISO particles with up to 20 w/0 enriched uranium kernels loaded in Pressurized Water

  10. Thermodynamics of hydrogen bonding and van der Waals interactions of organic solutes in solutions of imidazolium based ionic liquids: “Structure-property” relationships

    Energy Technology Data Exchange (ETDEWEB)

    Varfolomeev, Mikhail A., E-mail: vma.ksu@gmail.com; Khachatrian, Artashes A.; Akhmadeev, Bulat S.; Solomonov, Boris N.

    2016-06-10

    Highlights: • Solution enthalpies of organic solutes in imidazolium based ionic liquids were measured. • van der Waals interactions scale of imidazolium based ionic liquids was proposed. • Enthalpies of solvation of organic solutes in ionic liquids were determined. • Hydrogen bond enthalpies of organic solutes with ionic liquids were calculated. • Relationships between structure of ionic liquids and thermochemical data were obtained. - Abstract: In the present work thermochemistry of intermolecular interactions of organic compounds in solutions of imidazolium based ionic liquids (ILs) has been studied using solution calorimetry method. Enthalpies of solution at infinite dilution of non-polar (alkanes, aromatic hydrocarbons) and polar (alcohols, amides, and etc.) organic solutes in two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate were measured at 298.15 K. The scale of van der Waals interactions of imidazolium based ILs has been proposed on the basis of solution enthalpies of n-alkanes in their media. The effect of the cation and anion structure of ILs on the enthalpies of solvation was analyzed. Enthalpies of hydrogen bonding of organic solutes with imidazolium based ILs were determined. It has been shown that these values are close to zero for proton acceptor solutes. At the same time, enthalpies of hydrogen bonding of proton donor solutes with ionic liquids are increased depending the anion: tetrafluoroborate ≈ bis(trifluoromethylsulfonyl)imide < 2-(2-methoxyethoxy)ethyl sulfate < trifluoromethanesulfonate. Enthalpies of van der Waals interactions and hydrogen bonding in the solutions of imidazolium based ionic liquids were compared with the same data for molecular solvents.

  11. Thermodynamics of hydrogen bonding and van der Waals interactions of organic solutes in solutions of imidazolium based ionic liquids: “Structure-property” relationships

    International Nuclear Information System (INIS)

    Varfolomeev, Mikhail A.; Khachatrian, Artashes A.; Akhmadeev, Bulat S.; Solomonov, Boris N.

    2016-01-01

    Highlights: • Solution enthalpies of organic solutes in imidazolium based ionic liquids were measured. • van der Waals interactions scale of imidazolium based ionic liquids was proposed. • Enthalpies of solvation of organic solutes in ionic liquids were determined. • Hydrogen bond enthalpies of organic solutes with ionic liquids were calculated. • Relationships between structure of ionic liquids and thermochemical data were obtained. - Abstract: In the present work thermochemistry of intermolecular interactions of organic compounds in solutions of imidazolium based ionic liquids (ILs) has been studied using solution calorimetry method. Enthalpies of solution at infinite dilution of non-polar (alkanes, aromatic hydrocarbons) and polar (alcohols, amides, and etc.) organic solutes in two ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium trifluoromethanesulfonate were measured at 298.15 K. The scale of van der Waals interactions of imidazolium based ILs has been proposed on the basis of solution enthalpies of n-alkanes in their media. The effect of the cation and anion structure of ILs on the enthalpies of solvation was analyzed. Enthalpies of hydrogen bonding of organic solutes with imidazolium based ILs were determined. It has been shown that these values are close to zero for proton acceptor solutes. At the same time, enthalpies of hydrogen bonding of proton donor solutes with ionic liquids are increased depending the anion: tetrafluoroborate ≈ bis(trifluoromethylsulfonyl)imide < 2-(2-methoxyethoxy)ethyl sulfate < trifluoromethanesulfonate. Enthalpies of van der Waals interactions and hydrogen bonding in the solutions of imidazolium based ionic liquids were compared with the same data for molecular solvents.

  12. Self-organization of vortex-length distribution in quantum turbulence: An approach based on the Barabasi-Albert model

    International Nuclear Information System (INIS)

    Mitani, Akira; Tsubota, Makoto

    2006-01-01

    The energy spectrum of decaying quantum turbulence at T=0 obeys Kolmogorov's law. In addition to this, recent studies revealed that the vortex-length distribution (VLD), meaning the size distribution of the vortices, in decaying Kolmogorov quantum turbulence also obeys a power law. This power-law VLD suggests that the decaying turbulence has scale-free structure in real space. Unfortunately, however, there has been no practical study that answers the following important question: why can quantum turbulence acquire a scale-free VLD? We propose here a model to study the origin of the power law of the VLD from a generic point of view. The nature of quantized vortices allows one to describe the decay of quantum turbulence with a simple model that is similar to the Barabasi-Albert model, which explains the scale-invariance structure of large networks. We show here that such a model can reproduce the power law of the VLD well

  13. A new assay based on terminal restriction fragment length polymorphism of homocitrate synthase gene fragments for Candida species identification.

    Science.gov (United States)

    Szemiako, Kasjan; Śledzińska, Anna; Krawczyk, Beata

    2017-08-01

    Candida sp. have been responsible for an increasing number of infections, especially in patients with immunodeficiency. Species-specific differentiation of Candida sp. is difficult in routine diagnosis. This identification can have a highly significant association in therapy and prophylaxis. This work has shown a new application of the terminal restriction fragment length polymorphism (t-RFLP) method in the molecular identification of six species of Candida, which are the most common causes of fungal infections. Specific for fungi homocitrate synthase gene was chosen as a molecular target for amplification. The use of three restriction enzymes, DraI, RsaI, and BglII, for amplicon digestion can generate species-specific fluorescence labeled DNA fragment profiles, which can be used to determine the diagnostic algorithm. The designed method can be a cost-efficient high-throughput molecular technique for the identification of six clinically important Candida species.

  14. Hydrogen Bonding, (1)H NMR, and Molecular Electron Density Topographical Characteristics of Ionic Liquids Based on Amino Acid Cations and Their Ester Derivatives.

    Science.gov (United States)

    Rao, Soniya S; Bejoy, Namitha Brijit; Gejji, Shridhar P

    2015-08-13

    Amino acid ionic liquids (AAILs) have attracted significant attention in the recent literature owing to their ubiquitous applications in diversifying areas of modern chemistry, materials science, and biosciences. The present work focuses on unraveling the molecular interactions underlying AAILs. Electronic structures of ion pairs consisting of amino acid cations ([AA(+)], AA = Gly, Ala, Val, Leu, Ile, Pro, Ser, Thr) and their ester substituted derivatives [AAE(+)] interacting with nitrate anion [NO3(-)] have been obtained from the dispersion corrected M06-2x density functional theory. The formation of ion pair is accompanied by the transfer of proton from quaternary nitrogen to anion facilitated via hydrogen bonding. The [Ile], [Pro], [Ser], and [Thr] and their esters reveal relatively strong inter- as well as intramolecular hydrogen-bonding interactions. Consequently, the hierarchy in binding energies of [AA][NO3] ion pairs and their ester analogues turns out to be [Gly] > [Ala] > [Ser] ∼ [Val] ∼ [Ile] > [Leu] ∼ [Thr] > [Pro]. The work underlines how the interplay of intra- as well as intermolecular hydrogen-bonding interactions in [AA]- and [AAE]-based ILs manifest in their infrared and (1)H NMR spectra. Substitution of -OCH3 functional group in [AA][NO3] ILs lowers the melting point attributed to weaker hydrogen-bonding interactions, making them suitable for room temperature applications. As opposed to gas phase structures, the presence of solvent (DMSO) does not bring about any proton transfer in the ion pairs or their ester analogues. Calculated (1)H NMR chemical shifts of the solvated structures agree well with those from experiment. Correlations of decomposition temperatures in [AA]- and [AAE]-based ILs with binding energies and electron densities at the bond critical point(s) in molecular electron density topography, have been established.

  15. 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...

  16. Environment-friendly adhesives for surface bonding of wood-based flooring using natural tannin to reduce formaldehyde and TVOC emission.

    Science.gov (United States)

    Kim, Sumin

    2009-01-01

    The objective of this research was to develop environment-friendly adhesives for face fancy veneer bonding of engineered flooring using the natural tannin form bark in the wood. The natural wattle tannin adhesive were used to replace UF resin in the formaldehyde-based resin system in order to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. PVAc was added to the natural tannin adhesive to increase viscosity of tannin adhesive for surface bonding. For tannin/PVAc hybrid adhesives, 5%, 10%, 20% and 30% of PVAc to the natural tannin adhesives were added. tannin/PVAc hybrid adhesives showed better bonding than the commercial natural tannin adhesive with a higher level of wood penetration. The initial adhesion strength was sufficient to be maintained within the optimum initial tack range. The standard formaldehyde emission test (desiccator method), field and laboratory emission cell (FLEC) and VOC analyzer were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with commercial the natural tannin adhesive and tannin/PVAc hybrid adhesives. By desiccator method and FLEC, the formaldehyde emission level of each adhesive showed the similar tendency. All adhesives satisfied the E(1) grade (below 1.5 mg/L) and E(0) grade (below 0.5 mg/L) with UV coating. VOC emission results by FLEC and VOC analyzer were different with the formaldehyde emission results. TVOC emission was slightly increased as adding PVAc.

  17. Effects of nano TiN addition on the microstructure and mechanical properties of TiC based steel bonded carbides

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi'an; DAI Haiyang; ZOU Yu

    2008-01-01

    TiC based steel bonded carbides with the addition of nano TiN were prepared by vicuum sintering techniques.The microstructure was investigated using scanning electron microscopy(SEM)and transmission electron microscopy (TEM),and the mechanical properties,such as bending strength,impact toughness,hardness,and density,were measured.The results indicate that the grain size becomes small and there is uniformity in the steel bonded carbide with nano addition;several smaller carbide particles are also found to be inlaid in the rim of the larger carbide grains and prevent the coalescence of TiC grains.The smaller and larger carbide grains joint firmly,and then the reduction of the average size of the grains leads to the increase in the mechanical properties of the steel bonded carbides with nano addition.But the mechanical properties do not increase monotonously with an increase in nano addition.When the nano TiN addition accounts for 6-8 wt.% of the amount of steel bonded carbides.the mechanical properties reach the maximum values and then decrease with further increase in nano TiN addition.

  18. Thermal decay of rhodopsin: role of hydrogen bonds in thermal isomerization of 11-cis retinal in the binding site and hydrolysis of protonated Schiff base.

    Science.gov (United States)

    Liu, Jian; Liu, Monica Yun; Nguyen, Jennifer B; Bhagat, Aditi; Mooney, Victoria; Yan, Elsa C Y

    2009-07-01

    Although thermal stability of the G protein-coupled receptor rhodopsin is directly related to its extremely low dark noise level and has recently generated considerable interest, the chemistry behind the thermal decay process of rhodopsin has remained unclear. Using UV-vis spectroscopy and HPLC analysis, we have demonstrated that the thermal decay of rhodopsin involves both hydrolysis of the protonated Schiff base and thermal isomerization of 11-cis to all-trans retinal. Examining the unfolding of rhodopsin by circular dichroism spectroscopy and measuring the rate of thermal isomerization of 11-cis retinal in solution, we conclude that the observed thermal isomerization of 11-cis to all-trans retinal happens when 11-cis retinal is in the binding pocket of rhodopsin. Furthermore, we demonstrate that solvent deuterium isotope effects are involved in the thermal decay process by decreasing the rates of thermal isomerization and hydrolysis, suggesting that the rate-determining step of these processes involves breaking hydrogen bonds. These results provide insight into understanding the critical role of an extensive hydrogen-bonding network on stabilizing the inactive state of rhodopsin and contribute to our current understanding of the low dark noise level of rhodopsin, which enables this specialized protein to function as an extremely sensitive biological light detector. Because similar hydrogen-bonding networks have also been suggested by structural analysis of two other GPCRs, beta1 and beta2 adrenergic receptors, our results could reveal a general role of hydrogen bonds in facilitating GPCR function.

  19. Stress analysis of mandibular implant overdenture with locator and bar/clip attachment: Comparative study with differences in the denture base length

    OpenAIRE

    Yoo, Jin Suk; Kwon, Kung-Rock; Noh, Kwantae; Lee, Hyeonjong; Paek, Janghyun

    2017-01-01

    PURPOSE The design of the attachment must provide an optimum stress distribution around the implant. In this study, for implant overdentures with a bar/clip attachment or a locator attachment, the stress transmitted to the implant in accordance with the change in the denture base length and the vertical pressure was measured and analyzed. MATERIALS AND METHODS Test model was created with epoxy resin. The strain gauges made a tight contact with implant surfaces. A universal testing machine was...

  20. 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.

  1. 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

  2. Evaluation of bonding strength of porcelain to some commercial nickel-base dental alloys and comparing their interface

    Directory of Open Access Journals (Sweden)

    Rahim Asghari Salavat

    2017-12-01

    Conclusion: To replace the replacing of deleterious elements from the chemical composition of dental alloys. The added new elements should control through the oxide layer and the formation of Cr2O3 in porcelain-alloy interfaces for adequate bond strength.

  3. Intermolecular Formation of Two C−C Bonds across Olefins Enabled by Boron-Based Relay Strategies

    Czech Academy of Sciences Publication Activity Database

    Hidasová, Denisa; Jahn, Ullrich

    2017-01-01

    Roč. 56, č. 33 (2017), s. 9656-9658 ISSN 1433-7851 Institutional support: RVO:61388963 Keywords : 1,2- metal ate rearrangement * C−C bond formation * radical reactions * transition metal catalysis * vinyl boronates Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 11.994, year: 2016

  4. Evaluation of failure characteristics and bond strength after ceramic and polycarbonate bracket debonding : effect of bracket base silanization

    NARCIS (Netherlands)

    Ozcan, M.; Finnema, K.; Ybema, A.

    The objectives of this study were to evaluate the effect of silanization on the failure type and shear-peel bond strength (SBS) of ceramic and polycarbonate brackets, and to determine the type of failure when debonded with either a universal testing machine or orthodontic pliers. Silanized and

  5. Why are convertible bond announcements associated with increasingly negative abnormal stock returns? An arbitrage-based explanation

    NARCIS (Netherlands)

    Duca, E.; Dutordoir, M.; Veld, C.; Verwijmeren, P.

    2012-01-01

    While convertible offerings announced between 1984 and 1999 induce average abnormal stock returns of -1.69%, convertible announcement effects over the period 2000-2008 are more than twice as negative (-4.59%). We hypothesize that this evolution is attributable to a shift in the convertible bond

  6. The Effect of Bracket Base Pylon Orientation on the Shear Bond Strength of the ODP ANCHOR-LOCK Bracket Pad

    Science.gov (United States)

    2013-06-06

    in the dark) ( Bourke et al., 1992; McClean et al., 1994). Resin-modified glass ionomer cements that possess photochemical settling reactions also...primer/adhesive on the shear bond strength of orthodontic brackets. Am J Orthod Dentofacial Orthop 2001; 119(6):621-624. 61 Bourke AM, Walls AW

  7. 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

  8. Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling

    Science.gov (United States)

    Amare, Belachew N.

    Due to the need to increase the efficiency of modern power plants, land-based gas turbines are designed to operate at high temperature creating harsh environments for structural materials. The elevated turbine inlet temperature directly affects the materials at the hottest sections, which includes combustion chamber, blades, and vanes. Therefore, the hottest sections should satisfy a number of material requirements such as high creep strength, ductility at low temperature, high temperature oxidation and corrosion resistance. Such requirements are nowadays satisfied by implementing superalloys coated by high temperature thermal barrier coating (TBC) systems to protect from high operating temperature required to obtain an increased efficiency. Oxide dispersive strengthened (ODS) alloys are being considered due to their high temperature creep strength, good oxidation and corrosion resistance for high temperature applications in advanced power plants. These alloys operating at high temperature are subjected to different loading systems such as thermal, mechanical, and thermo-mechanical combined loads at operation. Thus, it is critical to study the high temperature mechanical and microstructure properties of such alloys for their structural integrity. The primary objective of this research work is to investigate the mechanical and microstructure properties of nickel-based ODS alloys produced by combined mechano-chemical bonding (MCB) and ball milling subjected to high temperature oxidation, which are expected to be applied for high temperature turbine coating with micro-channel cooling system. Stiffness response and microstructure evaluation of such alloy systems was studied along with their oxidation mechanism and structural integrity through thermal cyclic exposure. Another objective is to analyze the heat transfer of ODS alloy coatings with micro-channel cooling system using finite element analysis (FEA) to determine their feasibility as a stand-alone structural

  9. Inhibition of enamel demineralization and bond-strength properties of bioactive glass containing 4-META/MMA-TBB-based resin adhesive.

    Science.gov (United States)

    Kohda, Naohisa; Iijima, Masahiro; Kawaguchi, Kyotaro; Toshima, Hirokazu; Muguruma, Takeshi; Endo, Kazuhiko; Mizoguchi, Itaru

    2015-06-01

    We investigated the enamel demineralization-prevention ability and shear bond strength (SBS) properties of 4-methacryloxyethyl trimellitic anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB)-based resin containing various amounts (0-50%) of bioactive glass (BG). Disk-shaped specimens were immersed in distilled water and ions released were analysed by inductively coupled plasma atomic-emission spectroscopy. Samples were also immersed in lactic acid solution (pH 4.6) to estimate acid-neutralizing ability. Brackets were bonded to human premolars with BG-containing resins and the bonded teeth were alternately immersed in demineralizing (pH 4.55) and remineralizing (pH 6.8) solutions for 14 d. The enamel hardness was determined by nanoindentation testing at twenty equidistant distances from the external surface. The SBS for each sample was examined. The amounts of ions released [calcium (Ca), sodium (Na), silicon (Si), and boron (B)] and the acid-neutralizing ability increased with increasing BG content. After alternating immersion, the specimens bonded with the BG-containing resin with high BG content were harder than those in the other groups in some locations 1-18.5 μm from the enamel surface. Bioactive glass-containing (10-40%) resin had bond strength equivalent to the control specimen. Thus, the SBS obtained for BG-containing resin (6.5-9.2 MPa) was clinically acceptable, suggesting that this material has the ability to prevent enamel demineralization. © 2015 Eur J Oral Sci.

  10. Degree of conversion of resin-based orthodontic bonding materials cured with single-wave or dual-wave LED light-curing units.

    Science.gov (United States)

    Santini, Ario; McGuinness, Niall; Nor, Noor Azreen Md

    2014-12-01

    To evaluate the degree of conversion (DC) of orthodontic adhesives (RBOAs) cured with dual peak or single peak light-emitting diode (LED) light-curing units (LCUs). Standardized samples of RBOAs, APCPlus, Opal® Bond® and LightBond(TM) were prepared (n = 3) and cured with one of two dual peak LCUs (bluephase® G2-Ivoclar-Vivadent or Valo-Ultradent) or a single peak control (bluephase® Ivoclar-Vivadent). The DC was determined using micro-Raman spectroscopy. The presence or absence of initiators other than camphorquinone was confirmed by high-performance liquid chromatography and nuclear magnetic resonance spectroscopy. Data were analysed using general linear model in Minitab 15 (Minitab Inc., State College, PA, USA). There was no significant difference in DC between APCPlus, and Opal® Bond (confidence interval: -3.89- to 2.48); significant difference between APCPlus and LightBond(TM) (-18.55 to -12.18) and Opal® Bond and Lightbond(TM) (-17.85 to -11.48); no significant difference between bluephase (single peak) and dual peak LCUs, bluephase G2 (-4.896 to 1.476) and Valo (-3.935 to 2.437) and between bluephase G2 and Valo (-2.225 to 4.147). APCPlus and Opal® Bond showed higher DC values than LightBond(TM) (P<0.05). Lucirin® TPO was found only in Vit-l-escence. Lucirin® TPO was not identified in the three orthodontic adhesives. All three LCUs performed similarly with the orthodontic adhesives: orthodontic adhesive make had a greater effect on DC than the LCUs. It is strongly suggested that manufacturers of resin-based orthodontic materials test report whether or not dual peak LCUs should be used with their materials. Dual peak LED LCUs, though suitable in the majority of cases, may not be recommended for certain non Lucirin® TPO-containing materials. © 2014 British Orthodontic Society.

  11. 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.

  12. Field-Assisted Splitting of Pure Water Based on Deep-Sub-Debye-Length Nanogap Electrochemical Cells.

    Science.gov (United States)

    Wang, Yifei; Narayanan, S R; Wu, Wei

    2017-08-22

    Owing to the low conductivity of pure water, using an electrolyte is common for achieving efficient water electrolysis. In this paper, we have fundamentally broken through this common sense by using deep-sub-Debye-length nanogap electrochemical cells to achieve efficient electrolysis of pure water (without any added electrolyte) at room temperature. A field-assisted effect resulted from overlapped electrical double layers can greatly enhance water molecules ionization and mass transport, leading to electron-transfer limited reactions. We have named this process "virtual breakdown mechanism" (which is completely different from traditional mechanisms) that couples the two half-reactions together, greatly reducing the energy losses arising from ion transport. This fundamental discovery has been theoretically discussed in this paper and experimentally demonstrated in a group of electrochemical cells with nanogaps between two electrodes down to 37 nm. On the basis of our nanogap electrochemical cells, the electrolysis current density from pure water can be significantly larger than that from 1 mol/L sodium hydroxide solution, indicating the much better performance of pure water splitting as a potential for on-demand clean hydrogen production.

  13. 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

  14. Non-tables look-up search algorithm for efficient H.264/AVC context-based adaptive variable length coding decoding

    Science.gov (United States)

    Han, Yishi; Luo, Zhixiao; Wang, Jianhua; Min, Zhixuan; Qin, Xinyu; Sun, Yunlong

    2014-09-01

    In general, context-based adaptive variable length coding (CAVLC) decoding in H.264/AVC standard requires frequent access to the unstructured variable length coding tables (VLCTs) and significant memory accesses are consumed. Heavy memory accesses will cause high power consumption and time delays, which are serious problems for applications in portable multimedia devices. We propose a method for high-efficiency CAVLC decoding by using a program instead of all the VLCTs. The decoded codeword from VLCTs can be obtained without any table look-up and memory access. The experimental results show that the proposed algorithm achieves 100% memory access saving and 40% decoding time saving without degrading video quality. Additionally, the proposed algorithm shows a better performance compared with conventional CAVLC decoding, such as table look-up by sequential search, table look-up by binary search, Moon's method, and Kim's method.

  15. Development of a coherent transition radiation-based bunch length monitor with application to the APS RF thermionic gun beam optimization

    CERN Document Server

    Lumpkin, Alex H; Berg, W J; Borland, M; Happek, U; Lewellen, J W; Sereno, N S

    2001-01-01

    We report further development of an EPICS-compatible bunch length monitor based on the autocorrelation of coherent transition radiation (CTR). In this case the monitor was used to optimize the beam from the S-band thermionic RF gun on the Advanced Photon Source (APS) linac. Bunch lengths of 400-500 fs (FWHM) were measured in the core of the beam, which corresponded to about 100-A peak current in each micropulse. The dependence of the CTR signal on the square of the beam charge for the beam core was demonstrated. We also report the first use of the beam accelerated to 217 MeV for successful visible wavelength SASE FEL experiments.

  16. A stochastic length-based assessment model for the Pandalus stock in Skagerrak and the Norwegian Deep

    DEFF Research Database (Denmark)

    Nielsen, Anders; Munch-Petersen, Sten; Eigaard, Ole Ritzau

    2013-01-01

    in this paper is based on the assessment data presented at the 2012 NIPAG meeting, but with updated survey information. Also the estimates shown here are based on equal standard deviations for survey and catch L = (c) L , which is the natural assumption, as this parameter describes the standard deviation...

  17. 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...

  18. Spectroscopic studies of the intramolecular hydrogen bonding in o-hydroxy Schiff bases, derived from diaminomaleonitrile, and their deprotonation reaction products

    Science.gov (United States)

    Szady-Chełmieniecka, Anna; Kołodziej, Beata; Morawiak, Maja; Kamieński, Bohdan; Schilf, Wojciech

    2018-01-01

    The structural study of five Schiff bases derived from diaminomaleonitrile (DAMN) and 2-hydroxy carbonyl compounds was performed using 1H, 13C and 15N NMR methods in solution and in the solid state as well. ATR-FTIR and X-Ray spectroscopies were used for confirmation of the results obtained by NMR method. The imine obtained from DAMN and benzaldehyde was synthesized as a model compound which lacks intramolecular hydrogen bond. Deprotonation of all synthesized compounds was done by treating with tetramethylguanidine (TMG). NMR data revealed that salicylidene Schiff bases in DMSO solution exist as OH forms without intramolecular hydrogen bonds and independent on the substituents in aromatic ring. In the case of 2-hydroxy naphthyl derivative, the OH proton is engaged into weak intramolecular hydrogen bond. Two of imines (salDAMN and 5-BrsalDAMN) exist in DMSO solution as equilibrium mixtures of two isomers (A and B). The structures of equilibrium mixture in the solid state have been studied by NMR, ATR-FTIR and X-Ray methods. The deprotonation of three studied compounds (salDAMN, 5-BrsalDAMN, and 5-CH3salDAMN) proceeded in two different ways: deprotonation of oxygen atom (X form) or of nitrogen atom of free primary amine group of DAMN moiety (Y form). For 5-NO2salDAMN and naphDAMN only one form (X) was observed.

  19. Evaluation of the health status of preschool children stratified based on the weight-length index (WLI).

    Science.gov (United States)

    Shin, Kyung-Ok; Chung, Keun-Hee; Park, Hyun-Suh

    2010-10-01

    This study was conducted to prepare basic materials and offer advice regarding dietary habits to prevent and cure childhood obesity by comparing and analyzing dietary habit, nutritional status, blood factors, and mineral contents of hair. All subjects were stratified by their weight-length index (WLI). According to the standard WLI values, 64.9% of children were within the normal value, 13.5% of children were underweight, and 21.6% of children were overweight and obese (WLI ≥ 110%). Overall, the score assessed dietary habit for all children was 21.32 ± 2.55 point (921 subjects), with 5.1% of children having excellent dietary habits and 3.1% having poor dietary habits. Additionally, 37.9% of underweight children, 37.6% of normal weight children, and 43.2% of overweight and obese children consumed higher amounts of protein than underweight children did (meat, fish, eggs, and soy products) (P < 0.05). Overweight and obese children consumed more fried foods than underweight or normal weight children (P < 0.05). Moreover, 38.0% of the children had hemoglobin levels of 12 g/dl, while 7.6% were anemic (11.1 g/dl). When a hematocrit level of 33% was taken as the standard, 11.0% of children were anemic. The plasma transferrin content was 263.76 ± 54.52 mg/dl in overweight and obese children. The mean values of Fe, Cu, Ca, Cr, Mn, Se, Na, K, Li, V, Co, and Mo were within the reference values, but the Zn concentrations of underweight, normal weight, and overweight and obese children were 67.97 ± 28.51 ppm, 70.09 ± 30.81 ppm, and 73.99 ± 30.36 ppm, respectively. The Zn concentration of overweight and obese children (73.99 ± 30.36 ppm) was lower than that of the standard value (180~220 ppm). Therefore, a nutritional education program and new guidance for dietary pattern should be developed to reduce the number of underweight and overweight and obese children.

  20. Effect of Various Treatment Modalities on Surface Characteristics and Shear Bond Strengths of Polyetheretherketone-Based Core Materials.

    Science.gov (United States)

    Çulhaoğlu, Ahmet Kürşat; Özkır, Serhat Emre; Şahin, Volkan; Yılmaz, Burak; Kılıçarslan, Mehmet Ali

    2017-11-13

    To investigate the effect of different surface treatments on the surface roughness (Ra), wettability, and shear bond strength of polyetheretherketone (PEEK) to composite resin. One hundred ninety eight PEEK specimens were divided into six groups (n = 33). Specimen surfaces were treated with the following surface treatment modalities: silicoating (CoJet), acetone treatment, acid etching (H 2 SO 4 ), airborne particle abrasion (Al 2 O 3 ), laser irradiation (Yb:PL laser), and the nontreated surface serving as the control. Surface roughness was measured with an profilometer (n = 11) and a goniometer was used to measure the surface wettability through contact angle (θ)(n = 11). PEEK surfaces were veneered with a composite resin (n = 11). The specimens were then thermocycled for 10,000 cycles at 5 to 55°C. Shear bond strengths between the PEEK and composite resin were measured with an universal test machine. One-way ANOVA was used to analyze the data. Tukey's post-hoc test was used to determine significant differences between groups (α = 0.05). Surface roughness and wettability of PEEK surfaces along with shear bond strength of PEEK to composite resin were influenced by the surface treatments. (p PEEK surfaces treated by laser irradiation (2.85 ± 0.2 µm) followed by airborne particle abrasion (2.26 ± 0.33 µm), whereas other surface treatment modalities provided similar Ra values, with the acid-etched PEEK surfaces having the lowest mean Ra values (0.35 ± 0.14 µm). Silicoating provided the most wettable PEEK surfaces (48.04 ± 6.28º), followed by either acetone treatment (70.19 ± 4.49º) or acid treatment (76.07 ± 6.61º). Decreased wettability was observed for airborne particle abraded (84.83 ± 4.56º) and laser-treated PEEK surfaces (103.06 ± 4.88º). The highest mean shear bond strength values were observed for acid-etched PEEK surfaces (15.82 ± 4.23 MPa) followed by laser irradiated (11.46 ± 1.97 MPa), airborne particle abraded (10.81 ± 3.06 MPa

  1. 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....

  2. Lewis acid-base interactions in weakly bound formaldehyde complexes with CO2, HCN, and FCN: considerations on the cooperative H-bonding effects.

    Science.gov (United States)

    Rivelino, Roberto

    2008-01-17

    Ab initio quantum chemistry calculations reveal that HCN and mainly FCN can form Lewis acid-base complexes with formaldehyde associated with cooperative H bonds, as first noticed by Wallen et al. (Blatchford, M. A.; Raveendran, P.; Wallen, S. L. J. Am. Chem. Soc. 2002, 124, 14818-14819) for CO2-philic materials under supercritical conditions. The present results, obtained with MP2(Full)/aug-cc-pVDZ calculations, show that the degeneracy of the nu(2) mode in free HCN or FCN is removed upon complexation in the same fashion as that of CO2. The splitting of these bands along with the electron structure analysis provides substantial evidence of the interaction of electron lone pairs of the carbonyl oxygen with the electron-deficient carbon atom of the cyanides. Also, this work investigates the role of H bonds acting as additional stabilizing interactions in the complexes by performing the energetic and geometric characterization.

  3. Effect of transient liquid phase (TLP) bonding on the ductility of a Ni-base single crystal superalloy in a stress rupture test

    International Nuclear Information System (INIS)

    Liu, J.D.; Jin, T.; Zhao, N.R.; Wang, Z.H.; Sun, X.F.; Guan, H.R.; Hu, Z.Q.

    2008-01-01

    A Ni-base single crystal superalloy was transient liquid phase (TLP) bonded using a Ni-Cr-B amorphous foil at 1230 deg. C for 8 h. Stress rupture tests of the TLP joint and a matrix sample were carried out at 982 deg. C/248 MPa and 1010 deg. C/248 MPa. The microstructures and fracture surfaces were studied using scanning electron microscopy (SEM). Transmission electron microscopy (TEM) investigations were performed after creep rupture testing to examine the deformation substructures. The results show that the stress rupture ductility of TLP joints is significantly decreased compared to the matrix sample. This reduction of the ductility of TLP joints can be attributed to solid solution strengthening by boron atoms, subgrain boundaries formed in the bonding zone and the concentration of creep cavities formed during the last stage of the stress rupture test

  4. Improved stability of a metallic state in benzothienobenzothiophene-based molecular conductors: an effective increase of dimensionality with hydrogen bonds.

    Science.gov (United States)

    Higashino, Toshiki; Ueda, Akira; Yoshida, Junya; Mori, Hatsumi

    2017-03-25

    A dihydroxy-substituted benzothienobenzothiophene, BTBT(OH) 2 , was synthesized, and its charge-transfer (CT) salt, β-[BTBT(OH) 2 ] 2 ClO 4 , was successfully obtained. Thanks to the introduced hydroxy groups, a hydrogen-bonded chain structure connecting the BTBT molecules and counter anions was formed in the CT salt, which effectively increases the dimensionality of the electronic structure and consequently leads to a stable metallic state.

  5. Nitroxide stable radicals interacting as Lewis bases in hydrogen bonds: A search in the Cambridge structural data base for intermolecular contacts

    Science.gov (United States)

    Alkorta, Ibon; Elguero, José; Elguero, Eric

    2017-11-01

    1125 X-ray structures of nitroxide free radicals presenting intermolecular hydrogen bonds have been reported in the Cambridge Structural Database. We will report in this paper a qualitative and quantitative analysis of these bonds. The observation in some plots of an excluded region was statistically analyzed using convex hull and kernel smooting methodologies. A theoretical study at the MP2 level with different basis has been carried out indicating that the nitronyl nitroxide radicals (five electrons) lie just in between nitroso compounds (four electrons) and amine N-oxides (six electrons) as far as hydrogen-bond basicity is concerned.

  6. Ultrasonic Relaxation Study of 1-Alkyl-3-methylimidazolium-Based Room-Temperature Ionic Liquids: Probing the Role of Alkyl Chain Length in the Cation.

    Science.gov (United States)

    Zorębski, Michał; Zorębski, Edward; Dzida, Marzena; Skowronek, Justyna; Jężak, Sylwia; Goodrich, Peter; Jacquemin, Johan

    2016-04-14

    Ultrasound absorption spectra of four 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides were determined as a function of the alkyl chain length on the cation from 1-propyl to 1-hexyl from 293.15 to 323.15 K at ambient pressure. Herein, the ultrasound absorption measurements were carried out using a standard pulse technique within a frequency range from 10 to 300 MHz. Additionally, the speed of sound, density, and viscosity have been measured. The presence of strong dissipative processes during the ultrasound wave propagation was found experimentally, i.e., relaxation processes in the megahertz range were observed for all compounds over the whole temperature range. The relaxation spectra (both relaxation amplitude and relaxation frequency) were shown to be dependent on the alkyl side chain length of the 1-alkyl-3-methylimidazolium ring. In most cases, a single-Debye model described the absorption spectra very well. However, a comparison of the determined spectra with the spectra of a few other imidazolium-based ionic liquids reported in the literature (in part recalculated in this work) shows that the complexity of the spectra increases rapidly with the elongation of the alkyl chain length on the cation. This complexity indicates that both the volume viscosity and the shear viscosity are involved in relaxation processes even in relatively low frequency ranges. As a consequence, the sound velocity dispersion is present at relatively low megahertz frequencies.

  7. Measurement of the Length of Installed Rock Bolt Based on Stress Wave Reflection by Using a Giant Magnetostrictive (GMS) Actuator and a PZT Sensor.

    Science.gov (United States)

    Luo, Mingzhang; Li, Weijie; Wang, Bo; Fu, Qingqing; Song, Gangbing

    2017-02-23

    Rock bolts, as a type of reinforcing element, are widely adopted in underground excavations and civil engineering structures. Given the importance of rock bolts, the research outlined in this paper attempts to develop a portable non-destructive evaluation method for assessing the length of installed rock bolts for inspection purposes. Traditionally, piezoelectric elements or hammer impacts were used to perform non-destructive evaluation of rock bolts. However, such methods suffered from many major issues, such as the weak energy generated and the requirement for permanent installation for piezoelectric elements, and the inconsistency of wave generation for hammer impact. In this paper, we proposed a portable device for the non-destructive evaluation of rock bolt conditions based on a giant magnetostrictive (GMS) actuator. The GMS actuator generates enough energy to ensure multiple reflections of the stress waves along the rock bolt and a lead zirconate titantate (PZT) sensor is used to detect the reflected waves. A new integrated procedure that involves correlation analysis, wavelet denoising, and Hilbert transform was proposed to process the multiple reflection signals to determine the length of an installed rock bolt. The experimental results from a lab test and field tests showed that, by analyzing the instant phase of the periodic reflections of the stress wave generated by the GMS transducer, the length of an embedded rock bolt can be accurately determined.

  8. A colorimetric platform for sensitively differentiating telomere DNA with different lengths, monitoring G-quadruplex and dsDNA based on silver nanoclusters and unmodified gold nanoparticles

    Science.gov (United States)

    Qu, Fei; Chen, Zeqiu; You, Jinmao; Song, Cuihua

    2018-05-01

    Human telomere DNA plays a vital role in genome integrity control and carcinogenesis as an indication for extensive cell proliferation. Herein, silver nanoclusters (Ag NCs) templated by polymer and unmodified gold nanoparticles (Au NPs) are designed as a new colorimetric platform for sensitively differentiating telomere DNA with different lengths, monitoring G-quadruplex and dsDNA. Ag NCs can produce the aggregation of Au NPs, so the color of Au NPs changes to blue and the absorption peak moves to 700 nm. While the telomere DNA can protect Au NPs from aggregation, the color turns to red again and the absorption band blue shift. Benefiting from the obvious color change, we can differentiate the length of telomere DNA by naked eyes. As the length of telomere DNA is longer, the variation of color becomes more noticeable. The detection limits of telomere DNA containing 10, 22, 40, 64 bases are estimated to be 1.41, 1.21, 0.23 and 0.22 nM, respectively. On the other hand, when telomere DNA forms G-quadruplex in the presence of K+, or dsDNA with complementary sequence, both G-quadruplex and dsDNA can protect Au NPs better than the unfolded telomere DNA. Hence, a new colorimetric platform for monitoring structure conversion of DNA is established by Ag NCs-Au NPs system, and to prove this type of application, a selective K+ sensor is developed.

  9. Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

    Directory of Open Access Journals (Sweden)

    Torben Fiedler

    2014-11-01

    Full Text Available To increase the lifetime of rocket combustion chambers, thermal barrier coatings (TBC may be applied on the copper chamber wall. Since standard TBC systems used in gas turbines are not suitable for rocket-engine application and fail at the interface between the substrate and bond coat, a new bond-coat material has to be designed. This bond-coat material has to be chemically compatible to the copper substrate to improve the adhesion and needs a coefficient of thermal expansion close to that of copper to reduce thermal stresses. One approach to achieve this is to modify the standard NiCrAlY alloy used in gas turbines by adding copper. In this work, the influence of copper on the microstructure of NiCrAlY-alloys is investigated with thermodynamical calculations, optical microscopy, SEM, EDX and calorimetry. Adding copper leads to the formation of a significant amount of \\(\\beta\\ and \\(\\alpha\\ Reducing the aluminum and chromium content leads furthermore to a two-phase fcc microstructure.

  10. Effect of double bonds on the conducting properties of ciguatoxin 3C and tetrahydropyrane-based polymers: a theoretical study.

    Science.gov (United States)

    Matus, Myrna H; Garza, Jorge; Galván, Marcelo

    2006-01-26

    The electronic structure of the ciguatoxin 3C is analyzed through the Kohn-Sham model by using two different kinds of basis sets: localized basis set (Gaussian functions) and nonlocalized basis set (plane wave functions). With the localized basis functions, two approximations are used for the exchange-correlation functional: the local density approximation and the generalized gradient approximation. With the nonlocalized basis set, just the local density approximation is used. The energy gap, obtained from the frontier molecular orbitals, for this molecule predicts that this system is a semiconductor, even when the number of double bonds is increased inside the structure. However, as large molecules built with the basic unit--the tetrahydropyrane--of the ciguatoxin 3C are found in nature, it suggests studying the gap in polymeric systems built with the basic unit of this molecule. It is demonstrated that the presence of double bonds reduces considerably the gap, indicating the possibility of forming conducting materials by introducing double bonds in this kind of molecular systems. Thus, molecules strongly linked with biological systems can be used as precursor to build electric conducting systems.

  11. The effect of coating patterns with spinel-based investment on the castability and porosity of titanium cast into three phosphate-bonded investments.

    Science.gov (United States)

    Pieralini, Anelise R F; Benjamin, Camila M; Ribeiro, Ricardo Faria; Scaf, Gulnara; Adabo, Gelson Luis

    2010-10-01

    This study evaluated the effect of pattern coating with spinel-based investment Rematitan Ultra (RU) on the castability and internal porosity of commercially pure (CP) titanium invested into phosphate-bonded investments. The apparent porosity of the investment was also measured. Square patterns (15 × 15 × 0.3 mm(3)) were either coated with RU, or not and invested into the phosphate-bonded investments: Rematitan Plus (RP), Rema Exakt (RE), Castorit Super C (CA), and RU (control group). The castings were made in an Ar-arc vacuum-pressure machine. The castability area (mm(2) ) was measured by an image-analysis system (n = 10). For internal porosity, the casting (12 × 12 × 2 mm(3) ) was studied by the X-ray method, and the projected porous area percentage was measured by an image-analysis system (n = 10). The apparent porosity of the investment (n = 10) was measured in accordance with the ASTM C373-88 standard. Analysis of variance (One-way ANOVA) of castability was significant, and the Tukey test indicated that RU had the highest mean but the investing technique with coating increased the castability for all phosphate-bonded investments. The analysis of the internal porosity of the cast by the nonparametric test demonstrated that the RP, RE, and CA with coating and RP without coating did not differ from the control group (RU), while the CA and RE casts without coating were more porous. The one-way ANOVA of apparent porosity of the investment was significant, and the Tukey test showed that the means of RU (36.10%) and CA (37.22%) were higher than those of RP (25.91%) and RE (26.02%). Pattern coating with spinel-based material prior to phosphate-bonded investments can influence the castability and the internal porosity of CP Ti. © 2010 by The American College of Prosthodontists.

  12. Proton transfer and hydrogen bonding in the organic solid state: a combined XRD/XPS/ssNMR study of 17 organic acid-base complexes.

    Science.gov (United States)

    Stevens, Joanna S; Byard, Stephen J; Seaton, Colin C; Sadiq, Ghazala; Davey, Roger J; Schroeder, Sven L M

    2014-01-21

    The properties of nitrogen centres acting either as hydrogen-bond or Brønsted acceptors in solid molecular acid-base complexes have been probed by N 1s X-ray photoelectron spectroscopy (XPS) as well as (15)N solid-state nuclear magnetic resonance (ssNMR) spectroscopy and are interpreted with reference to local crystallographic structure information provided by X-ray diffraction (XRD). We have previously shown that the strong chemical shift of the N 1s binding energy associated with the protonation of nitrogen centres unequivocally distinguishes protonated (salt) from hydrogen-bonded (co-crystal) nitrogen species. This result is further supported by significant ssNMR shifts to low frequency, which occur with proton transfer from the acid to the base component. Generally, only minor chemical shifts occur upon co-crystal formation, unless a strong hydrogen bond is formed. CASTEP density functional theory (DFT) calculations of (15)N ssNMR isotropic chemical shifts correlate well with the experimental data, confirming that computational predictions of H-bond strengths and associated ssNMR chemical shifts allow the identification of salt and co-crystal structures (NMR crystallography). The excellent agreement between the conclusions drawn by XPS and the combined CASTEP/ssNMR investigations opens up a reliable avenue for local structure characterization in molecular systems even in the absence of crystal structure information, for example for non-crystalline or amorphous matter. The range of 17 different systems investigated in this study demonstrates the generic nature of this approach, which will be applicable to many other molecular materials in organic, physical, and materials chemistry.

  13. Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population.

    Science.gov (United States)

    Bosco, Aju; Venugopal, Prakash; Shetty, Ajoy Prasad; Shanmuganathan, Rajasekaran; Kanna, Rishi Mugesh

    2018-04-01

    Computed tomographic (CT) morphometric analysis. To assess the feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomical zones and screw lengths for safe screw placement. Limitations of occipital squama-based OCF has led to development of two novel OC-based OCF techniques. Morphometric analysis was performed on the OCs of 70 Indian adults. The feasibility of placing a 3.5-mm-diameter screw into OCs was investigated. Safe trajectories and screw lengths for OC screws and C0-C1 transarticular screws without hypoglossal canal or atlantooccipital joint compromise were estimated. The average screw length and safe sagittal and medial angulations for OC screws were 19.9±2.3 mm, ≤6.4°±2.4° cranially, and 31.1°±3° medially, respectively. An OC screw could not be accommodated by 27% of the population. The safe sagittal angles and screw lengths for C0-C1 transarticular screw insertion (48.9°±5.7° cranial, 26.7±2.9 mm for junctional entry technique; 36.7°±4.6° cranial, 31.6±2.7 mm for caudal C1 arch entry technique, respectively) were significantly different than those in other populations. The risk of vertebral artery injury was high for the caudal C1 arch entry technique. Screw placement was uncertain in 48% of Indians due to the presence of aberrant anatomy. There were significant differences in the metrics of OC-based OCF between Indian and other populations. Because of the smaller occipital squama dimensions in Indians, OC-based OCF techniques may have a higher application rate and could be a viable alternative/salvage option in selected cases. Preoperative CT, including three-dimensional-CT-angiography (to delineate vertebral artery course), is imperative to avoid complications resulting from aberrant bony and vascular anatomy. Our data can serve as a valuable reference guide in placing these screws safely under fluoroscopic guidance.

  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. Critical determinant of intestinal permeability and oral bioavailability of pegylated all trans-retinoic acid prodrug-based nanomicelles: Chain length of poly (ethylene glycol) corona.

    Science.gov (United States)

    Li, Zhenbao; Han, Xiaopeng; Zhai, Yinglei; Lian, He; Zhang, Dong; Zhang, Wenjuan; Wang, Yongjun; He, Zhonggui; Liu, Zheng; Sun, Jin

    2015-06-01

    Pegylation method is widely used to prolong the blood circulation time of proteins and nanoparticles after intravenous administration, but the effect of surface poly (ethylene glycol) (PEG) chain length on oral absorption of the pegylated nanoparticles is poorly reported. The aim of our study was to investigate the influence of PEG corona chain length on membrane permeability and oral bioavailability of the amphiphilic pegylated prodrug-based nanomicelles, taking all trans-retinoic acid (ATRA) as a model drug. The amphiphilic ATRA-PEG conjugates were synthesized by esterification reaction between all trans-retinoic acid and mPEGs (mPEG500, mPEG1000, mPEG2000, and mPEG5000). The conjugates could self-assemble in aqueous medium to form nanomicelles by emulsion-solvent evaporation method. The resultant nanomicelles were in spherical shape with an average diameter of 13-20 nm. The drug loading efficiency of ATRA-PEG500, ATRA-PEG1000, ATRA-PEG2000, and ATRA-PEG5000 was about 38.4, 26.6, 13.1, and 5.68 wt%, respectively. With PEG chain length ranging from 500 to 5000, ATRA-PEG nanomicelles exhibited a bell shape of chemical stability in different pH buffers, intestinal homogenate and plasma. More importantly, they were all rapidly hydrolyzed into the parent drug in hepatic homogenate, with the half-time values being 0.3-0.4h. In comparison to ATRA solution and ATRA prodrug-based nanomicelles, ATRA-PEG1000 showed the highest intestinal permeability. After oral administration, ATRA-PEG2000 and ATRA-PEG5000 nanomicelles were not nearly absorbed, while the oral bioavailability of ATRA-PEG500 and ATRA-PEG1000 demonstrated about 1.2- and 2.0-fold higher than ATRA solution. Our results indicated that PEG1000 chain length of ATRA-PEG prodrug nanomicelles has the optimal oral bioavailability probably due to improved stability and balanced mucus penetration capability and cell binding, and that the PEG chain length on a surface of nanoparticles cannot exceed a key threshold with

  17. A simple semi-empirical approximation for bond energy

    International Nuclear Information System (INIS)

    Jorge, F.E.; Giambiagi, M.; Giambiagi, M.S. de.

    1985-01-01

    A simple semi-empirical expression for bond energy, related with a generalized bond index, is proposed and applied within the IEH framework. The correlation with experimental data is good for the intermolecular bond energy of base pairs of nucleic acids and other hydrogen bonded systems. The intramolecular bond energies for a sample of molecules containing typical bonds and for hydrides are discussed. The results are compared with those obtained by other methods. (Author) [pt

  18. Ion Mobility Separations of Isomers based upon Long Path Length Structures for Lossless Ion Manipulations Combined with Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Liulin [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Ibrahim, Yehia M. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Baker, Erin S. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Aly, Noor A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Hamid, Ahmed M. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Zhang, Xing [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Zheng, Xueyun [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Garimella, Sandilya V. B. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Webb, Ian K. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Prost, Spencer A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Sandoval, Jeremy A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Norheim, Randolph V. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Anderson, Gordon A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Tolmachev, Aleksey V. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Smith, Richard D. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA

    2016-07-01

    Mass spectrometry (MS)-based multi-omic measurements, including proteomics, metabolomics, lipidomics, and glycomics, are increasingly transforming our ability to characterize and understand biological systems, but, presently have limitations due to the chemical diversity and range of abundances of biomolecules in complex samples. Advances addressing these challenges increasingly are based upon the ability to quickly separate, react and otherwise manipulate sample components for analysis by MS. Here we report on a new approach using Structures for Lossless Ion Manipulations (SLIM) to enable long serpentine path ion mobility spectrometry (IMS) separations followed by MS analyses. This approach provides previously unachieved mobility biomolecule isomer separations for biomolecular species, in conjunction with more effective ion utilization, and producing a basis for the improved characterization of very small samples.

  19. Mechanisms of strand break formation in DNA due to the direct effect of ionizing radiation: the dependency of free base release on the length of alternating CG oligodeoxynucleotides.

    Science.gov (United States)

    Sharma, Kiran K; Razskazovskiy, Yuriy; Purkayastha, Shubhadeep; Bernhard, William A

    2009-06-11

    The question of how NA base sequence influences the yield of DNA strand breaks produced by the direct effect of ionizing radiation was investigated in a series of oligodeoxynucleotides of the form (d(CG)(n))(2) and (d(GC)(n))(2). The yields of free base release from X-irradiated DNA films containing 2.5 waters/nucleotide were measured by HPLC as a function of oligomer length. For (d(CG)(n))(2), the ratio of the Gua yield to Cyt yield, R, was relatively constant at 2.4-2.5 for n = 2-4 and it decreased to 1.2 as n increased from 5 to 10. When Gua was moved to the 5' end, for example going from d(CG)(5) to d(GC)(5), R dropped from 1.9 +/- 0.1 to 1.1 +/- 0.1. These effects are poorly described if the chemistry at the oligomer ends is assumed to be independent of the remainder of the oligomer. A mathematical model incorporating charge transfer through the base stack was derived to explain these effects. In addition, EPR was used to measure the yield of trapped-deoxyribose radicals at 4 K following X-irradiation at 4 K. The yield of free base release was substantially greater, by 50-100 nmol/J, than the yield of trapped-deoxyribose radicals. Therefore, a large fraction of free base release stems from a nonradical intermediate. For this intermediate, a deoxyribose carbocation formed by two one-electron oxidations is proposed. This reaction pathway requires that the hole (electron loss site) transfers through the base stack and, upon encountering a deoxyribose hole, oxidizes that site to form a deoxyribose carbocation. This reaction mechanism provides a consistent way of explaining both the absence of trapped radical intermediates and the unusual dependence of free base release on oligomer length.

  20. Density functional theory study of β-hairpins in antiparallel β-sheets, a new classification based upon H-bond topology.

    Science.gov (United States)

    Roy, Dipankar; Pohl, Gabor; Ali-Torres, Jorge; Marianski, Mateusz; Dannenberg, J J

    2012-07-10

    We present a new classification of β-turns specific to antiparallel β-sheets based upon the topology of H-bond formation. This classification results from ONIOM calculations using B3LYP/D95** density functional theory and AM1 semiempirical calculations as the high and low levels, respectively. We chose acetyl(Ala)(6)NH(2) as a model system as it is the simplest all-alanine system that can form all the H-bonds required for a β-turn in a sheet. Of the 10 different conformations we have found, the most stable structures have C(7) cyclic H-bonds in place of the C(10) interactions specified in the classic definition. Also, the chiralities specified for residues i + 1 and i + 2 in the classic definition disappear when the structures are optimized using our techniques, as the energetic differences among the four diastereomers of each structure are not substantial for 8 of the 10 conformations.

  1. Examination of hydrogen-bonding interactions between dissolved solutes and alkylbenzene solvents based on Abraham model correlations derived from measured enthalpies of solvation

    Energy Technology Data Exchange (ETDEWEB)

    Varfolomeev, Mikhail A.; Rakipov, Ilnaz T. [Chemical Institute, Kazan Federal University, Kremlevskaya 18, Kazan 420008 (Russian Federation); Acree, William E., E-mail: acree@unt.edu [Department of Chemistry, 1155 Union Circle # 305070, University of North Texas, Denton, TX 76203-5017 (United States); Brumfield, Michela [Department of Chemistry, 1155 Union Circle # 305070, University of North Texas, Denton, TX 76203-5017 (United States); Abraham, Michael H. [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2014-10-20

    Highlights: • Enthalpies of solution measured for 48 solutes dissolved in mesitylene. • Enthalpies of solution measured for 81 solutes dissolved in p-xylene. • Abraham model correlations derived for enthalpies of solvation of solutes in mesitylene. • Abraham model correlations derived for enthalpies of solvation of solutes in p-xylene. • Hydrogen-bonding enthalpies reported for interactions of aromatic hydrocarbons with hydrogen-bond acidic solutes. - Abstract: Enthalpies of solution at infinite dilution of 48 organic solutes in mesitylene and 81 organic solutes in p-xylene were measured using isothermal solution calorimeter. Enthalpies of solvation for 92 organic vapors and gaseous solutes in mesitylene and for 130 gaseous compounds in p-xylene were determined from the experimental and literature data. Abraham model correlations are determined from the experimental enthalpy of solvation data. The derived correlations describe the experimental gas-to-mesitylene and gas-to-p-xylene solvation enthalpies to within average standard deviations of 1.87 kJ mol{sup −1} and 2.08 kJ mol{sup −1}, respectively. Enthalpies of X-H⋯π (X-O, N, and C) hydrogen bond formation of proton donor solutes (alcohols, amines, chlorinated hydrocarbons etc.) with mesitylene and p-xylene were calculated based on the Abraham solvation equation. Obtained values are in good agreement with the results determined using conventional methods.

  2. Streptococcus mutans counts in plaque adjacent to orthodontic brackets bonded with resin-modified glass ionomer cement or resin-based composite

    Directory of Open Access Journals (Sweden)

    Solange Machado Mota

    2008-03-01

    Full Text Available This study investigated the number of Streptococcus mutans CFU (colony forming units in the saliva and plaque adjacent to orthodontic brackets bonded with a glass ionomer cement - GIC (Fuji Ortho or a resin-based composite - RC (Concise. Twenty male and female patients, aged 12 to 20 years, participated in the study. Saliva was collected before and after placement of appliances. Plaque was collected from areas adjacent to brackets and saliva was again collected on the 15th, 30th, and 45th day after placement. On the 30th day, 0.4% stannous fluoride gel was applied for 4 minutes. No significant modification in the number of Streptococcus mutans CFU in saliva was observed after placement of the fixed orthodontic appliances. On the 15th day, the percentage of Streptococcus mutans CFU in plaque was statistically lower in sites adjacent to GIC-bonded brackets (mean = 0.365 than in those adjacent to RC-bonded brackets (mean = 0.935. No evidence was found of a contribution of GIC to the reduction of CFU in plaque after the 15th day. Topical application of stannous fluoride gel on the 30th day reduced the number of CFU in saliva, but not in plaque. This study suggests that the antimicrobial activity of GIC occurs only in the initial phase and is not responsible for a long-term anticariogenic property.

  3. A METHOD OF EXTRACTING SHORELINE BASED ON SEMANTIC INFORMATION USING DUAL-LENGTH LiDAR DATA

    Directory of Open Access Journals (Sweden)

    C. Yao

    2017-09-01

    Full Text Available Shoreline is a spatial varying separation between water and land. By utilizing dual-wavelength LiDAR point data together with semantic information that shoreline often appears beyond water surface profile and is observable on the beach, the paper generates the shoreline and the details are as follows: (1 Gain the water surface profile: first we obtain water surface by roughly selecting water points based on several features of water body, then apply least square fitting method to get the whole water trend surface. Then we get the ground surface connecting the under -water surface by both TIN progressive filtering method and surface interpolation method. After that, we have two fitting surfaces intersected to get water surface profile of the island. (2 Gain the sandy beach: we grid all points and select the water surface profile grids points as seeds, then extract sandy beach points based on eight-neighborhood method and features, then we get all sandy beaches. (3 Get the island shoreline: first we get the sandy beach shoreline based on intensity information, then we get a threshold value to distinguish wet area and dry area, therefore we get the shoreline of several sandy beaches. In some extent, the shoreline has the same height values within a small area, by using all the sandy shoreline points to fit a plane P, and the intersection line of the ground surface and the shoreline plane P can be regarded as the island shoreline. By comparing with the surveying shoreline, the results show that the proposed method can successfully extract shoreline.

  4. Magnetic feature and near-infrared absorption of a [Pt(mnt)2]-based H-bond supramolecular crystal

    International Nuclear Information System (INIS)

    Li, Cui-Ping; Nie, Li; Pei, Wen-Bo; Li, Li; Tian, Zheng-Fang; Liu, Jian-Lan; Gao, Xu-Sheng; Ren, Xiao-Ming

    2016-01-01

    A new salt [H 2 DABCO][Pt(mnt) 2 ] 2 (1) (mnt 2- =maleonitriledithiolate and H 2 DABCO 2+ is diprotonated 1,4-diazabicyclo[2.2.2]octane) has been synthesized; its crystal structure, magnetic and near-IR absorption properties have been investigated. Two different [Pt(mnt) 2 ] - anions form the strong π-dimers, labeled as Pt(1)-dimer and Pt(2)-dimer, with quite shorter Pt…Pt and S…S distances and molecular plane-to-plane distance (<3.5 Å) within a dimer. The [Pt(mnt) 2 ] 2 2- π-dimers are connected through the cations in the strong H-bond manner to form three-dimensional H-bond supramolecular crystal. The salt shows weak paramagnetism in 1.99–300 K and this is due to the existence of strong antiferromagnetic coupling within a π-dimer. In addition, a small thermal hysteresis loop is observed at ca. 120 K, indicating that a phase transition probably occurs that is further confirmed by variable-temperature IR spectra. Another fascinating functionality of 1 is the intense near-IR absorption in the region of 750–2500 nm, and this near-IR absorption feature makes it to be a promising optical material. - Graphical abstract: A H-bond supramolecular crystal of [H 2 DABCO][Pt(mnt) 2 ] 2 shows a magnetic phase transition at ca. 120 K with sizable thermal hysteresis loop and intense near-IR absorption in the region of 750–2500 nm.

  5. Analysis of parameters for technological equipment of parallel kinematics based on rods of variable length for processing accuracy assurance

    Science.gov (United States)

    Koltsov, A. G.; Shamutdinov, A. H.; Blokhin, D. A.; Krivonos, E. V.

    2018-01-01

    A new classification of parallel kinematics mechanisms on symmetry coefficient, being proportional to mechanism stiffness and accuracy of the processing product using the technological equipment under study, is proposed. A new version of the Stewart platform with a high symmetry coefficient is presented for analysis. The workspace of the mechanism under study is described, this space being a complex solid figure. The workspace end points are reached by the center of the mobile platform which moves in parallel related to the base plate. Parameters affecting the processing accuracy, namely the static and dynamic stiffness, natural vibration frequencies are determined. The capability assessment of the mechanism operation under various loads, taking into account resonance phenomena at different points of the workspace, was conducted. The study proved that stiffness and therefore, processing accuracy with the use of the above mentioned mechanisms are comparable with the stiffness and accuracy of medium-sized series-produced machines.

  6. Construction of an SNP-based high-density linkage map for flax (Linum usitatissimum L.) using specific length amplified fragment sequencing (SLAF-seq) technology.

    Science.gov (United States)

    Yi, Liuxi; Gao, Fengyun; Siqin, Bateer; Zhou, Yu; Li, Qiang; Zhao, Xiaoqing; Jia, Xiaoyun; Zhang, Hui

    2017-01-01

    Flax is an important crop for oil and fiber, however, no high-density genetic maps have been reported for this species. Specific length amplified fragment sequencing (SLAF-seq) is a high-resolution strategy for large scale de novo discovery and genotyping of single nucleotide polymorphisms. In this study, SLAF-seq was employed to develop SNP markers in an F2 population to construct a high-density genetic map for flax. In total, 196.29 million paired-end reads were obtained. The average sequencing depth was 25.08 in male parent, 32.17 in the female parent, and 9.64 in each F2 progeny. In total, 389,288 polymorphic SLAFs were detected, from which 260,380 polymorphic SNPs were developed. After filtering, 4,638 SNPs were found suitable for genetic map construction. The final genetic map included 4,145 SNP markers on 15 linkage groups and was 2,632.94 cM in length, with an average distance of 0.64 cM between adjacent markers. To our knowledge, this map is the densest SNP-based genetic map for flax. The SNP markers and genetic map reported in here will serve as a foundation for the fine mapping of quantitative trait loci (QTLs), map-based gene cloning and marker assisted selection (MAS) for flax.

  7. Variation in Wood Quality in White Spruce (Picea Glauca (Moench Voss. Part I. Defining the Juvenile–Mature Wood Transition Based on Tracheid Length

    Directory of Open Access Journals (Sweden)

    Cyriac Serge Mvolo

    2015-01-01

    Full Text Available Estimations of transition age (TA and juvenile wood proportion (JWP are important for wood industries due to their impact on end-product quality. However, the relationships between analytical determination of TA based on tracheid length (TL and recognized thresholds for adequate end products have not yet been established. In this study, we used three different statistical models to estimate TA in white spruce (Picea glauca (Moench Voss based on TL radial variation. We compared the results with technological maturity. A two-millimeter threshold, previously suggested for good paper tear strength, was used. Tracheid length increased from pith to bark and from breast height to upper height. Juvenile wood (JW was conical with the three models. At breast height, TA ranged from 11 to 27 years and JWP ranged from 15.3% to 47.5% across the three models. The linear mixed model produced more conservative estimates than the maximum-quadratic-linear (M_Q_L model. Both the linear mixed model and the M_Q_L model produced more conservative TA estimates than the piecewise model. TA estimates by the MIXED model, and to a lesser extent by the M_Q_L model, were equivalent to those for real mature wood, whereas TA estimates by the piecewise model were considerably lower, falling into the transition wood area.

  8. Design and fabrication of PMMA-micromachined fluid lens based on electromagnetic actuation on PMMA–PDMS bonded membrane

    International Nuclear Information System (INIS)

    Lee, June Kyoo; Park, Kyung-Woo; Choi, Ju Chan; Kim, Hak-Rin; Kong, Seong Ho

    2012-01-01

    The fabrication of a poly(methyl methacrylate) (PMMA)-micromachined fluid lens with an optimally designed built-in electromagnetic actuator was demonstrated in this study. Through a finite element method, the number of winding turns and the distance between magnetic moments were estimated to design an effective and miniaturized electromagnetic actuator. The lens body composed of PMMA structures was simply and rapidly micromachined using computer numerical control micro-milling. The poly(dimethylsiloxane) (PDMS) membranes for electromagnetic actuation were bonded to the PMMA structures by using the proposed PMMA–PDMS bonding technique, which uses an SiO 2 intermediate layer. A physical repulsive force produced by the electromagnetic actuator applies a controllable fluidic pressure to a fluidic chamber that is sealed with the PDMS membrane, thus allowing dynamic focusing. The focus tunability of the fabricated lens was 67 diopters with a focus hysteresis of less than 1 mm and a response time of 2 ms. The solenoid of the built-in actuator showed negligible thermal crosstalk to the lens. (paper)

  9. The demagnetising factors for bonded neodymium iron boron (NdFeB) magnets

    International Nuclear Information System (INIS)

    Wang, Z.

    2000-10-01

    Both analytical and computational methods have been, for the first time, employed to study the demagnetising factors for bonded magnets. The demagnetising factors for bonded NdFeB magnets are dependent on the external shape of the bonded magnet, the shapes of magnetic particles, the magnetic loading percentage and the distributions of magnetic particles. Particularly, it has been shown that the demagnetising factor along the length of an infinitely long bonded magnet is not equal to zero but that it also depends on the shapes of the magnetic particles, magnetic loading percentage and the distribution of magnetic particles. However, the sum of the demagnetising factors along the x, y and z directions is, as expected, unity for all bonded magnets. The demagnetising factor for a fully dense magnet, which is dependent only on the external shape of the magnet, can be considered as a special case of bonded magnets in which the magnetic loading is 100%. Simplified formulae for calculating the demagnetising factors for simple shaped magnets such as cuboid, cylindroid and ellipsoid shapes were obtained and the values are in reasonable agreement with precise analytical solutions. A Lorentz ''sphere'' concept has, for the first time, been employed to calculate the demagnetising factors for hollow magnets and bonded NdFeB magnets. The simplified formulae for hollow magnets and bonded magnets were derived. Computer programmes based on the basic energy method were developed and employed to calculate the demagnetising factors for bonded magnet models, such as a one-dimensional NdFeB ribbon array, two-dimensional bonded magnets and three-dimensional bonded magnets. A finite difference method and a finite element method have been, for the first time, employed to calculate the demagnetising factors for two-dimensional bonded magnet models and the results are comparable with those obtained using the basic energy method. Procedures for calculating demagnetising curves (J vs H) for

  10. 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.

  11. Self assembly of dialkoxo bridged dinuclear Fe(III) complex of pyridoxal Schiff base with C-C bond formation - structure, spectral and magnetic properties

    Czech Academy of Sciences Publication Activity Database

    Murašková, V.; Szabó, N.; Pižl, M.; Hoskovcová, I.; Dušek, Michal; Huber, Š.; Sedmidubský, D.

    2017-01-01

    Roč. 461, May (2017), s. 111-119 ISSN 0020-1693 R&D Projects: GA ČR(CZ) GA15-12653S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : iron(III) dinuclear complex * dialkoxo bridged pyridoxal Schiff base * C-C bond * crystal structure * magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.002, year: 2016

  12. Oxide-Free Bonding of III-V-Based Material on Silicon and Nano-Structuration of the Hybrid Waveguide for Advanced Optical Functions

    Directory of Open Access Journals (Sweden)

    Konstantinos Pantzas

    2015-10-01

    Full Text Available Oxide-free bonding of III-V-based materials for integrated optics is demonstrated on both planar Silicon (Si surfaces and nanostructured ones, using Silicon on Isolator (SOI or Si substrates. The hybrid interface is characterized electrically and mechanically. A hybrid InP-on-SOI waveguide, including a bi-periodic nano structuration of the silicon guiding layer is demonstrated to provide wavelength selective transmission. Such an oxide-free interface associated with the nanostructured design of the guiding geometry has great potential for both electrical and optical operation of improved hybrid devices.

  13. 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.

  14. 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

  15. 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.

  16. Highly stretchable strain sensor based on polyurethane substrate using hydrogen bond-assisted laminated structure for monitoring of tiny human motions

    Science.gov (United States)

    Huang, Ying; Zhao, Yunong; Wang, Yang; Guo, Xiaohui; Zhang, Yangyang; Liu, Ping; Liu, Caixia; Zhang, Yugang

    2018-03-01

    Strain sensors used as flexible and wearable electronic devices have improved prospects in the fields of artificial skin, robotics, human-machine interfaces, and healthcare. This work introduces a highly stretchable fiber-based strain sensor with a laminated structure made up of a graphene nanoplatelet layer and a carbon black/single-walled carbon nanotube synergetic conductive network layer. An ultrathin, flexible, and elastic two-layer polyurethane (PU) yarn substrate was successively deposited by a novel chemical bonding-based layered dip-coating process. These strain sensors demonstrated high stretchability (˜350%), little hysteresis, and long-term durability (over 2400 cycles) due to the favorable tensile properties of the PU substrate. The linearity of the strain sensor could reach an adjusted R-squared of 0.990 at 100% strain, which is better than most of the recently reported strain sensors. Meanwhile, the strain sensor exhibited good sensibility, rapid response, and a lower detection limit. The lower detection limit benefited from the hydrogen bond-assisted laminated structure and continuous conductive path. Finally, a series of experiments were carried out based on the special features of the PU strain sensor to show its capacity of detecting and monitoring tiny human motions.

  17. Age, growth and population structure of invasive lionfish (Pterois volitans/miles in northeast Florida using a length-based, age-structured population model

    Directory of Open Access Journals (Sweden)

    Eric G. Johnson

    2016-12-01

    Full Text Available The effective management of invasive species requires detailed understanding of the invader’s life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish (Pterois volitans/miles have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1 lionfish exhibited rapid growth with seasonal variation in growth rates; (2 distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3 the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water.

  18. Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model.

    Science.gov (United States)

    Johnson, Eric G; Swenarton, Mary Katherine

    2016-01-01

    The effective management of invasive species requires detailed understanding of the invader's life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish ( Pterois volitans/miles ) have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1) lionfish exhibited rapid growth with seasonal variation in growth rates; (2) distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3) the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water.

  19. Understanding the stable boron clusters: A bond model and first-principles calculations based on high-throughput screening

    International Nuclear Information System (INIS)

    Xu, Shao-Gang; Liao, Ji-Hai; Zhao, Yu-Jun; Yang, Xiao-Bao

    2015-01-01

    The unique electronic property induced diversified structure of boron (B) cluster has attracted much interest from experimentalists and theorists. B 30–40 were reported to be planar fragments of triangular lattice with proper concentrations of vacancies recently. Here, we have performed high-throughput screening for possible B clusters through the first-principles calculations, including various shapes and distributions of vacancies. As a result, we have determined the structures of B n clusters with n = 30–51 and found a stable planar cluster of B 49 with a double-hexagon vacancy. Considering the 8-electron rule and the electron delocalization, a concise model for the distribution of the 2c–2e and 3c–2e bonds has been proposed to explain the stability of B planar clusters, as well as the reported B cages

  20. Correspondence optimization in 2D standardized carotid wall thickness map by description length minimization: A tool for increasing reproducibility of 3D ultrasound-based measurements.

    Science.gov (United States)

    Chen, Yimin; Chiu, Bernard

    2016-12-01

    The previously described 2D standardized vessel-wall-plus-plaque thickness (VWT) maps constructed from 3D ultrasound vessel wall measurements using an arc-length (AL) scaling approach adjusted the geometric variability of carotid arteries and has allowed for the comparisons of VWT distributions in longitudinal and cross-sectional studies. However, this mapping technique did not optimize point correspondence of the carotid arteries investigated. The potential misalignment may lead to errors in point-wise VWT comparisons. In this paper, we developed and validated an algorithm based on steepest description length (DL) descent to optimize the point correspondence implied by the 2D VWT maps. The previously described AL approach was applied to obtain initial 2D maps for a group of carotid arteries. The 2D maps were reparameterized based on an iterative steepest DL descent approach, which consists of the following two steps. First, landmarks established by resampling the 2D maps were aligned using the Procrustes algorithm. Then, the gradient of the DL with respect to horizontal and vertical reparameterizations of each landmark on the 2D maps was computed, and the 2D maps were subsequently deformed in the direction of the steepest descent of DL. These two steps were repeated until convergence. The quality of the correspondence was evaluated in a phantom study and an in vivo study involving ten carotid arteries enrolled in a 3D ultrasound interscan variability study. The correspondence quality was evaluated in terms of the compactness and generalization ability of the statistical shape model built based on the established point correspondence in both studies. In the in vivo study, the effect of the proposed algorithm on interscan variability of VWT measurements was evaluated by comparing the percentage of landmarks with statistically significant VWT-change before and after point correspondence optimization. The statistical shape model constructed with optimized

  1. Creation and validation of the Singapore birth nomograms for birth weight, length and head circumference based on a 12-year birth cohort.

    Science.gov (United States)

    Poon, Woei Bing; Fook-Chong, Stephanie M C; Ler, Grace Y L; Loh, Zhi Wen; Yeo, Cheo Lian

    2014-06-01

    Both gestation and birth weight have significant impact on mortality and morbidity in newborn infants. Nomograms at birth allow classification of infants into small for gestational age (SGA) and large for gestational age (LGA) categories, for risk stratification and more intensive monitoring. To date, the growth charts for preterm newborn infants in Singapore are based on the Fenton growth charts, which are constructed based on combining data from various Western growth cohorts. Hence, we aim to create Singapore nomograms for birth weight, length and head circumference at birth, which would reflect the norms and challenges faced by local infants. Growth parameters of all babies born or admitted to our unit from 2001 to 2012 were retrieved. Following exclusion of outliers, nomograms for 3 percentiles of 10th, 50th, and 90th were generated for the gestational age (GA) ranges of 25 to 42 weeks using quantile regression (QR) combined with the use of restricted cubic splines. Various polynomial models (second to third degrees) were investigated for suitability of fit. The optimum QR model was found to be a third degree polynomial with a single knotted cubic spline in the mid-point of the GA range, at 33.5 weeks. Check for goodness of fit was done by visual inspection first. Next, check was performed to ensure the correct proportion: 10% of all cases fall above the upper 90th percentile and 10% fall below the lower 10th percentile. Furthermore, an alternative formula-based method of nomogram construction, using mean, standard deviation (SD) and assumption of normality at each gestational age, was used for counterchecking. A total of 13,403 newborns were included in the analysis. The new infant-foetal growth charts with respect to birth weight, heel-crown length and occipitofrontal circumference from 25 to 42 weeks gestations with the 10th, 50th and 90th were presented. Nomograms for birth weight, length and head circumference at birth had significant impact on neonatal

  2. Liquidity in Government versus Covered Bond Markets

    DEFF Research Database (Denmark)

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

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

  3. FE modeling of Cu wire bond process and reliability

    NARCIS (Netherlands)

    Yuan, C.A.; Weltevreden, E.R.; Akker, P. van den; Kregting, R.; Vreugd, J. de; Zhang, G.Q.

    2011-01-01

    Copper based wire bonding technology is widely accepted by electronic packaging industry due to the world-wide cost reduction actions (compared to gold wire bond). However, the mechanical characterization of copper wire differs from the gold wire; hence the new wire bond process setting and new bond

  4. Development of a method to accurately calculate the Dpb and quickly predict the strength of a chemical bond

    International Nuclear Information System (INIS)

    Du, Xia; Zhao, Dong-Xia; Yang, Zhong-Zhi

    2013-01-01

    Highlights: ► A method from new respect to characterize and measure the bond strength is proposed. ► We calculate the D pb of a series of various bonds to justify our approach. ► A quite good linear relationship of the D pb with the bond lengths for series of various bonds is shown. ► Take the prediction of strengths of C–H and N–H bonds for base pairs in DNA as a practical application of our method. - Abstract: A new approach to characterize and measure bond strength has been developed. First, we propose a method to accurately calculate the potential acting on an electron in a molecule (PAEM) at the saddle point along a chemical bond in situ, denoted by D pb . Then, a direct method to quickly evaluate bond strength is established. We choose some familiar molecules as models for benchmarking this method. As a practical application, the D pb of base pairs in DNA along C–H and N–H bonds are obtained for the first time. All results show that C 7 –H of A–T and C 8 –H of G–C are the relatively weak bonds that are the injured positions in DNA damage. The significance of this work is twofold: (i) A method is developed to calculate D pb of various sizable molecules in situ quickly and accurately; (ii) This work demonstrates the feasibility to quickly predict the bond strength in macromolecules

  5. Effect of curing modes of dual-curing core systems on microtensile bond strength to dentin and formation of an acid-base resistant zone.

    Science.gov (United States)

    Li, Na; Takagaki, Tomohiro; Sadr, Alireza; Waidyasekera, Kanchana; Ikeda, Masaomi; Chen, Jihua; Nikaido, Toru; Tagami, Junji

    2011-12-01

    To evaluate the microtensile bond strength (μTBS) and acid-base resistant zone (ABRZ) of two dualcuring core systems to dentin using four curing modes. Sixty-four caries-free human molars were randomly divided into two groups according to two dual-curing resin core systems: (1) Clearfil DC Core Automix; (2) Estelite Core Quick. For each core system, four different curing modes were applied to the adhesive and core resin: (1) dual-cured and dual-cured (DD); (2) chemically cured and dual-cured (CD); (3) dual-cured and chemically cured (DC); (4) chemically cured and chemically cured (CC). The specimens were sectioned into sticks (n = 20 for each group) for the microtensile bond test. μTBS data were analyzed using two-way ANOVA and the Dunnett T3 test. Failure patterns were examined with scanning electron microscopy (SEM) to determine the proportion of each mode. Dentin sandwiches were produced and subjected to an acid-base challenge. After argon-ion etching, the ultrastructure of ABRZ was observed using SEM. For Clearfil DC Core Automix, the μTBS values in MPa were as follows: DD: 29.1 ± 5.4, CD: 21.6 ± 5.6, DC: 17.9 ± 2.8, CC: 11.5 ± 3.2. For Estelite Core Quick, they were: DD: 48.9 ±5.7, CD: 20.5 ± 4.7, DC: 41.4 ± 8.3, CC: 19.1 ± 6.0. The bond strength was affected by both material and curing mode, and the interaction of the two factors was significant (p < 0.001). Within both systems, there were significant differences among groups, and the DD group showed the highest μTBS (p < 0.05). ABRZ morphology was not affected by curing mode, but it was highly adhesive-material dependent. The curing mode of dual-curing core systems affects bond strength to dentin, but has no significant effect on the formation of ABRZ.

  6. Dependency of Anion and Chain Length of Imidazolium Based Ionic Liquid on Micellization of the Block Copolymer F127 in Aqueous Solution: An Experimental Deep Insight

    Directory of Open Access Journals (Sweden)

    Jignesh Lunagariya

    2017-07-01

    Full Text Available The non-ionic triblock copolymer, Pluronic® F127, has been selected to observe its interaction with ionic liquids (ILs in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC of F127 increased with the addition of ILs, which appeared logical since it increases the solubility of PPO (and PEO moiety, making it behaves more like a hydrophilic block copolymer that is micellized at a higher copolymer concentration. The results from DLS data showed good agreement with those obtained from the surface tension measurements. Upon the addition of ILs, the tendency in micellar size reduction was demonstrated by viscosity results, and therefore, intrinsic viscosity decreased compared to pure F127 in aqueous solution. The results were discussed as a function of alkyl chain length and anions of imidazolium based ILs.

  7. AnSBBR with circulation applied to biohydrogen production treating sucrose based wastewater: effects of organic loading, influent concentration and cycle length

    Directory of Open Access Journals (Sweden)

    D. A. Santos

    2014-09-01

    Full Text Available An anaerobic sequencing batch biofilm reactor (AnSBBR containing immobilized biomass and operating with recirculation of the liquid phase (total liquid volume 4.5 L; treated volume per cycle 1.9 L was used to treat sucrose-based wastewater at 30 ºC and produce biohydrogen. The influence of applied volumetric organic load was studied by varying the influent concentration at 3600 and 5400 mgCOD.L-1 and using cycle lengths of 4, 3 and 2 hours, obtaining in this manner volumetric organic loads of 9, 12, 13.5, 18 and 27 gCOD.L-1.d-1. Different performance indicators were used: productivity and yield of biohydrogen per applied and removed load, reactor stability and efficiency based on the applied and removed organic loads, both in terms of organic matter (measured as COD and carbohydrate (sucrose. The results revealed system stability (32-37% of H2 in biogas during biohydrogen production, as well as substrate consumption (12-19% COD; 97-99% sucrose. Conversion efficiencies decreased when the influent concentration was increased (at constant cycle length and when cycle lengths were reduced (at constant influent concentrations. The best yield was 4.16 mol-H2.kg-SUC-1 (sucrose load at 9 gCOD.L-1.d-1 (3600 mgCOD.L-1 and 4 h with H2 content in the biogas of 36% (64% CO2 and 0% CH4. However, the best specific molar productivity of hydrogen was 8.5 molH2.kgTVS-1.d-1 (32% H2; 68% CO2; 0% CH4, at 18 gCOD.L-1.d-1 (5400 mgCOD.L-1 and 3 h, indicating that the best productivity tends to occur at higher organic loads, as this parameter involves the "biochemical generation" of biogas, whereas the best yield tends to occur at lower and/or intermediate organic loads, as this parameter involves "biochemical consumption" of the substrate. The most significant metabolites were ethanol, acetic acid and butyric acid. Microbiological analyses revealed that the biomass contained bacilli and endospore filaments and showed no significant variations in morphology between

  8. A novel bonding method for fabrication of PET planar nanofluidic chip with low dimension loss and high bonding strength

    International Nuclear Information System (INIS)

    Yin, Zhifu; Zou, Helin; Sun, Lei; Xu, Shenbo; Qi, Liping

    2015-01-01

    Plastic planar nanofluidic chips are becoming increasingly important for biological and chemical applications. However, the majority of the present bonding methods for planar nanofluidic chips suffer from high dimension loss and low bonding strength. In this work, a novel thermal bonding technique based on O 2 plasma and ethanol treatment was proposed. With the assistance of O 2 plasma and ethanol, the PET (polyethylene terephthalate) planar nanofluidic chip can be bonded at a low bonding temperature of 50 °C. To increase the bonding rate and bonding strength, the O 2 plasma parameters and thermal bonding parameters were optimized during the bonding process. The tensile test indicates that the bonding strength of the PET planar nanofluidic chip can reach 0.954 MPa, while the auto-fluorescence test demonstrates that there is no leakage or blockage in any of the bonded micro- or nanochannels. (paper)

  9. 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 — ...

  10. Crystal engineered acid–base complexes with 2D and 3D hydrogen bonding systems using p-hydroxybenzoic acid as the building block

    Directory of Open Access Journals (Sweden)

    PU SU ZHAO

    2010-04-01

    Full Text Available p-Hydroxybenzoic acid (p-HOBA was selected as the building block for self-assembly with five bases, i.e., diethylamine, tert-butylamine, cyclohexylamine, imidazole and piperazine, and generation of the corresponding acid–base complexes 1–5. Crystal structure analyses suggest that proton-transfer from the carboxyl hydr