435 research outputs found

    Copolyamides of nylon-4,6 and nylon-4,T

    Get PDF
    Copolyamides of nylon-4,6 and nylon-4,T were prepared by a two-step method: (1) a prepolymerization in an autoclave (40 min at 210°C) and (2) a postcondensation in the solid state (4 h, 260°C). On these materials was studied the melting behavior with DSC, the crystalline structure with WAXS, the water absorption, and the mechanical properties with a torsion pendulum. In these copolyamides the order was found to remain high, but the crystalline structures of -4,6 and -4,T were not isomorphous. The torsion moduli increased with -4,T content both at RT and at 140°C

    Distribution of particles which produces a "smart" material

    Get PDF
    If Aq(ÎČ,α,k)A_q(\beta, \alpha, k) is the scattering amplitude, corresponding to a potential q∈L2(D)q\in L^2(D), where D⊂R3D\subset\R^3 is a bounded domain, and eikα⋅xe^{ik\alpha \cdot x} is the incident plane wave, then we call the radiation pattern the function A(ÎČ):=Aq(ÎČ,α,k)A(\beta):=A_q(\beta, \alpha, k), where the unit vector α\alpha, the incident direction, is fixed, and k>0k>0, the wavenumber, is fixed. It is shown that any function f(ÎČ)∈L2(S2)f(\beta)\in L^2(S^2), where S2S^2 is the unit sphere in R3\R^3, can be approximated with any desired accuracy by a radiation pattern: ∣∣f(ÎČ)−A(ÎČ)∣∣L2(S2)<Ï”||f(\beta)-A(\beta)||_{L^2(S^2)}<\epsilon, where Ï”>0\epsilon>0 is an arbitrary small fixed number. The potential qq, corresponding to A(ÎČ)A(\beta), depends on ff and Ï”\epsilon, and can be calculated analytically. There is a one-to-one correspondence between the above potential and the density of the number of small acoustically soft particles Dm⊂DD_m\subset D, 1≀m≀M1\leq m\leq M, distributed in an a priori given bounded domain D⊂R3D\subset\R^3. The geometrical shape of a small particle DmD_m is arbitrary, the boundary SmS_m of DmD_m is Lipschitz uniformly with respect to mm. The wave number kk and the direction α\alpha of the incident upon DD plane wave are fixed.It is shown that a suitable distribution of the above particles in DD can produce the scattering amplitude A(αâ€Č,α)A(\alpha',\alpha), αâ€Č,α∈S2\alpha',\alpha\in S^2, at a fixed k>0k>0, arbitrarily close in the norm of L2(S2×S2)L^2(S^2\times S^2) to an arbitrary given scattering amplitude f(αâ€Č,α)f(\alpha',\alpha), corresponding to a real-valued potential q∈L2(D)q\in L^2(D).Comment: corrected typo

    Advance Care Planning: A Story of Trust Within the Family.

    Get PDF
    As the family usually plays a central role at the end of life, the quality of family relationships may influence how individuals approach advance care planning (ACP). Our study investigates the associations of trust in relatives with regard to end-of-life (EOL) issues-used as a proxy measure of family relationship quality-with individuals' engagement in EOL discussions, advance directive (AD) awareness, approval and completion, and designation of a healthcare proxy. Using nationally representative data of adults aged 55 years and over from wave 6 (2015) of the Survey of Health, Ageing, and Retirement in Europe (SHARE) in Switzerland (n = 1911), we show that complete trust in relatives is related to higher engagement in ACP. Subject to patient consent, the family should, therefore, be included in the ACP process, as such practice could enhance patient-centered EOL care and quality of life at the end of life

    The sensitivity of the vortex filament method to different reconnection models

    Full text link
    We present a detailed analysis on the effect of using different algorithms to model the reconnection of vortices in quantum turbulence, using the thin-filament approach. We examine differences between four main algorithms for the case of turbulence driven by a counterflow. In calculating the velocity field we use both the local induction approximation (LIA) and the full Biot-Savart integral. We show that results of Biot-Savart simulations are not sensitive to the particular reconnection method used, but LIA results are.Comment: 9 pages, 9 figure

    Tree method for quantum vortex dynamics

    Full text link
    We present a numerical method to compute the evolution of vortex filaments in superfluid helium. The method is based on a tree algorithm which considerably speeds up the calculation of Biot-Savart integrals. We show that the computational cost scales as Nlog{(N) rather than N squared, where NN is the number of discretization points. We test the method and its properties for a variety of vortex configurations, ranging from simple vortex rings to a counterflow vortex tangle, and compare results against the Local Induction Approximation and the exact Biot-Savart law.Comment: 12 pages, 10 figure

    Photoswitching in nanoporous, crystalline solids: An experimental and theoretical study for azobenzene linkers incorporated in MOFs

    Get PDF
    In this article, we use the popular photoswitchable molecule, azobenzene, to demonstrate that the embedding in a nanoporous, crystalline solid enables a precise understanding of light-induced, reversible molecular motion. We investigate two similar azobenzene-containing, pillared-layer metal-organic frameworks (MOFs): Cu2(AzoBPDC)2(BiPy) and Cu2(NDC)2(AzoBiPy). Experimental results from UV-vis spectroscopy and molecular uptake experiments as well as theoretical results based on density-functional theory (DFT) show that in the Cu2(AzoBPDC)2(BiPy) MOF structure, the azobenzene side groups undergo photoisomerization when irradiated with UV or visible light. In a very similar MOF structure, Cu2(NDC)2(AzoBiPy), the experimental studies show an unexpected absence of photoisomerization. The DFT calculations reveal that in both MOFs the initial and final states of the photoswitching process (the trans and the cis conformation) have similar energies, which strongly suggests that the reason for the effective blocking of photoswitching in the AzoBiPy-based MOFs must be related to the switching process itself. More detailed calculations show that in Cu2(NDC)2(AzoBiPy) a naphthalene linker from the molecular framework blocks the photoisomerization trajectory which leads from the trans to the cis conformation. For Cu2(AzoBPDC)2(BiPy), as a result of the different geometry, such a steric hindrance is absent

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

    Get PDF
    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

    Get PDF
    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
    • 

    corecore