Two distinct lithium diffusive species for polymer gel electrolytes containing LiBF₄, propylene carbonate (PC) and PVDF

Polymer gel electrolytes have been prepared using lithium tetrafluoroborate (LiBF₄), propylene carbonate (PC) and polyvinylidene fluoride (PVDF) at 20% and 30% concentration by mass. Self diffusion coefficients have been measured using pulse field gradient nuclear magnetic resonance (PFG-NMR) for the cation and anion using ⁷Li and ¹⁹F resonant frequencies respectively. It was found that lithium ion diffusion was slow compared to the much larger fluorine anion likely resulting from a large solvation shell of the lithium. Lithium ion diffusion measurements exhibited two distinct diffusive species, whereas the fluorine ions exhibited only a single diffusive species

NMR Self Diffusion and Relaxation Time Measurements for Poly (vinylidene fluoride) (PVDF) Based Polymer Gel Electrolytes Containing LiBF4 and Propylene Carbonate

Polymer gel electrolytes (PGEs) have been prepared using lithium tetrafluoroborate (LiBF4), propylene carbonate (PC) and poly (vinylidene fluoride) (PVDF). Self diffusion coefficients have been measured using pulse field gradient nuclear magnetic resonance (PFG-NMR) for the lithium cation, BF4 anion and solvent molecules using 7Li, 19F and 1H nuclei, respectively. It was found that lithium ion diffusion was slow compared to the much larger fluorinated BF4 anion, which is attributed to a large solvation shell around the lithium ions. The 7Li and 1H diffusion measurements also exhibited two unique environments for the diffusive species. The measurement of NMR transverse relaxation times has confirmed the presence of lithium ions in multiple phases as shown by the diffusion measurements

Dynamic tilting in perovskites

A new computational analysis of tilt behaviour in perovskites is presented. This includes the development of a computational program – PALAMEDES – to extract tilt angles and the tilt phase from molecular dynamics simulations. The results are used to generate simulated selected-area electron and neutron diffraction patterns which are compared with experimental patterns for CaTiO3. The simulations not only reproduced all symmetrically allowed superlattice reflections associated with tilt but also showed local correlations that give rise to symmetrically forbidden reflections and the kinematic origin of diffuse scattering

Yield conditions for deformation of amorphous polymer glasses

Shear yielding of glassy polymers is usually described in terms of the pressure-dependent Tresca or von Mises yield criteria. We test these criteria against molecular dynamics simulations of deformation in amorphous polymer glasses under triaxial loading conditions that are difficult to realize in experiments. Difficulties and ambiguities in extending several standard definitions of the yield point to triaxial loads are described. Two definitions, the maximum and offset octahedral stresses, are then used to evaluate the yield stress for a wide range of model parameters. In all cases, the onset of shear is consistent with the pressure-modified von Mises criterion, and the pressure coefficient is nearly independent of many parameters. Under triaxial tensile loading, the mode of failure changes to cavitation.Comment: 9 pages, 8 figures, revte

Cognitive and Motor Outcomes of Children With Prenatal Opioid Exposure

Importance: Prenatal opioid exposure (POE) is one of the fastest-growing global health problems, but its association with long-term neurologic and physical development remains unknown. Objective: To assess the association between POE and cognitive and motor development in children from age 6 months to 18 years. Data Sources: Key search terms included prenatal opioid exposure, neonatal abstinence syndrome, and neurocognitive development. Studies were searched using PubMed and Embase, with no publication date restriction, through August 20, 2018. Study Selection: Only published cohort studies comparing the results of age-appropriate standardized cognitive and/or motor tests between children with any POE (aged 0-18 years) with drug-free controls were included. Data that were not convertible to means and SDs were excluded. Data Extraction and Synthesis: This study was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Data were pooled using a random-effects model. Main Outcomes and Measures: Standardized mean difference of cognitive and motor tests between POE and nonexposed children. Results: Twenty-six peer-reviewed cohort studies were included. Cognitive outcomes were compared for a total of 1455 children with POE and 2982 nonexposed children across 3 age groups (mean [SE] age at cognitive testing was 13 [1.58] months for the toddler group; 4.5 [0.38] years for the preschool group; and 13 [2.36] years for the school-aged group). Motor outcomes were compared for 688 children with POE and 1500 nonexposed children up to age 6 years (mean [SD] age at motor testing, 2 [0.45] years). Standardized mean difference was lower in cognitive tests for children with POE at 0 to 2 years (d = −0.52; 95% CI, −0.74 to −0.31; P < .001) and 3 to 6 years (d = −0.38; 95% CI, −0.69 to −0.07; P < .001); the difference was not significant for those aged 7 to 18 years (d = −0.44; 95% CI, −1.16 to 0.28; P = .23). Motor scores were lower in children with POE (d = 0.49; 95% CI, 0.23-0.74; P < .001). Conclusions and Relevance: Prenatal opioid exposure appeared to be negatively associated with neurocognitive and physical development from age 6 months, and this association persisted until adolescence. The cause and association of this with POE or other factors (eg, withdrawal treatment) are uncertain but suggest that POE necessitates long-term support and intervention

Notes on Exact Multi-Soliton Solutions of Noncommutative Integrable Hierarchies

We study exact multi-soliton solutions of integrable hierarchies on noncommutative space-times which are represented in terms of quasi-determinants of Wronski matrices by Etingof, Gelfand and Retakh. We analyze the asymptotic behavior of the multi-soliton solutions and found that the asymptotic configurations in soliton scattering process can be all the same as commutative ones, that is, the configuration of N-soliton solution has N isolated localized energy densities and the each solitary wave-packet preserves its shape and velocity in the scattering process. The phase shifts are also the same as commutative ones. Furthermore noncommutative toroidal Gelfand-Dickey hierarchy is introduced and the exact multi-soliton solutions are given.Comment: 18 pages, v3: references added, version to appear in JHE

Implementation and Validation of Schapery-Rand Anisotropic Viscoelasticity Model for Super-Pressure Balloons

The thin film used for the NASA Ultra Long Duration Balloons (ULDB) shows con-siderable time-dependent behaviour. Furthermore, experiments on scaled ULDB balloons have revealed that wrinkles are present over a wide range of pressures. A numerical model has been developed describing the nonlinear anisotropic viscoelastic material behaviour by means of a Schapery-type model and this model has been extended to model wrinkling by means of a user-defined subroutine in the finite-element package ABAQUS. After a description of the viscoelastic modelling approach, a lobe of a 48 gore ULDB flat facet balloon is modelled and compared to experimental results. Additionally two test cases of anisotropic wrinkling are presented, one involving a flat membrane and one a cylindrical balloon structure. I

Simulations of the Static Friction Due to Adsorbed Molecules

The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potentials can have larger effects on friction. The observed trends in friction can be understood in terms of a simple hard sphere model.Comment: 13 pages, 13 figure

Strangeness Enhancement in p+Ap+A and S+AS+A Interactions at SPS Energies

The systematics of strangeness enhancement is calculated using the HIJING and VENUS models and compared to recent data on $\,pp\,$, $\,pA\,$ and $\,AA\,$ collisions at CERN/SPS energies ($200A\,\, GeV\,$). The HIJING model is used to perform a {\em linear} extrapolation from $pp$ to $AA$. VENUS is used to estimate the effects of final state cascading and possible non-conventional production mechanisms. This comparison shows that the large enhancement of strangeness observed in $S+Au$ collisions, interpreted previously as possible evidence for quark-gluon plasma formation, has its origins in non-equilibrium dynamics of few nucleon systems. % Strangeness enhancement %is therefore traced back to the change in the production dynamics %from $pp$ to minimum bias $pS$ and central $SS$ collisions. A factor of two enhancement of $\Lambda^{0}$ at mid-rapidity is indicated by recent $pS$ data, where on the average {\em one} projectile nucleon interacts with only {\em two} target nucleons. There appears to be another factor of two enhancement in the light ion reaction $SS$ relative to $pS$, when on the average only two projectile nucleons interact with two target ones.Comment: 29 pages, 8 figures in uuencoded postscript fil

The influence of the hybridisation configuration on the mechancial properties of hybrid self reinforced polyamide 12/carbon fibre composites

This paper compares and contrasts the properties of self-reinforced polyamide 12/carbon fibre hybrid composites made by three different hybridisation routes, termed intra-yarn, intra-layer and inter-layer. The starting point for each route was to manufacture layers of woven cloth (containing both components), from which the hybrid composites were manufactured using the Leeds hot compaction technique. In all cases, a carbon fibre volume fraction of around 8% was the target. On balance, the intra-layer hybrids had the best combination of properties, although all three hybridisation routes yielded interesting results. This intra-layer hybrid configuration showed a significant increase in tensile modulus and strength, bending modulus and strength and penetration impact energy compared to a pure self-reinforced polyamide sheet. The only negative aspect was a reduction in the tensile failure strain from 11 to 2%, whereas the ductility in bending was unaffected by the incorporation of the carbon fibres