Incremental expansions for Hubbard-Peierls systems

The ground state energies of infinite half-filled Hubbard-Peierls chains are investigated combining incremental expansion with exact diagonalization of finite chain segments. The ground state energy of equidistant infinite Hubbard (Heisenberg) chains is calculated with a relative error of less than $3 \cdot 10^{-3}$ for all values of $U$ using diagonalizations of 12-site (20-site) chain segm ents. For dimerized chains the dimerization order parameter $d$ as a function of the onsite repulsion interaction $U$ has a maximum at nonzero values of $U$, if the electron-phonon coupling $g$ is lower than a critical value $g_c$. The critical value $g_c$ is found with high accuracy to be $g_c=0.69$. For smaller values of $g$ the position of the maximum of $d(U)$ is approximately $3t$, and rapidly tends to zero as $g$ approaches $g_c$ from below. We show how our method can be applied to calculate breathers for the problem of phonon dynamics in Hubbard-Peierls systems.Comment: 4 Pages, 3 Figures, REVTE

An Artificial SEI Layer Based on an Inorganic Coordination Polymer with Self-Healing Ability for Long-Lived Rechargeable Lithium-Metal Batteries

Upon immersion of a lithium (Li) anode into a diluted 0.05 to 0.20 M dimethoxyethane solution of the phosphoric-acid derivative (CF$_{3}$CH$_{2}$O)$_{2}$P(O)OH (HBFEP), an artificial solid-electrolyte interphase (SEI) is generated on the Li-metal surface. Hence, HBFEP reacts on the surface to the corresponding Li salt (LiBFEP), which is a Li-ion conducting inorganic coordination polymer. This film exhibits – due to the reversibly breaking ionic bonds – self-healing ability upon cycling-induced volume expansion of Li. The presence of LiBFEP as the major component in the artificial SEI is proven by ATR-IR and XPS measurements. SEM characterization of HBFEP-treated Li samples reveals porous layers on top of the Li surface with at least 3 μm thickness. Li−Li symmetrical cells with HBFEP-modified Li electrodes show a three- to almost fourfold cycle-lifetime increase at 0.1 mA cm$^{-2}$ in a demanding model electrolyte that facilitates fast battery failure (1 M LiOTf in TEGDME). Hence, the LiBFEP-enriched layer apparently acts as a Li-ion conducting protection barrier between Li and the electrolyte, enhancing the rechargeability of Li electrodes

Synthesis of poly(methyl methacrylate)-poly(poly(ethylene glycol) methacrylate)-polyisobutylene ABCBA pentablock copolymers by combining quasiliving carbocationic and atom transfer radical polymerizations and characterization thereof

Novel, unique amphiphilic pentab lock terpolymers consisting of the highly hydrophobic polyisobutylene (PIB) mid - segment attached to the hydrophilic combshaped poly(poly(ethylene glycol ) methacrylate) (PPEGMA) polymacromonomer chains, which are coupled to poly(methyl methacrylate) (PMMA) outer segments were synthesized by the combination of quasiliving carbocationic polymerization and atom transfer radical polymerization ( ATRP ) . First, a bifunctional PIB macroinitiator w as prepared by quasiliving carbocationic polymerization and subsequent quantitative chain end derivatizations. ATRP of PEGMAs with different molecular weights (M n = 188, 300 and 475 g/mol) led to triblock copolymers which were further reacted with MMA under ATRP conditions to obtain P MMA - PPE G MA - PIB - PPEGMA - PMMA AB CB A - type pen ta block copolymers . It was found that slow initi ation takes place between the PIB macroinitiator and PEGMA macromonomers with higher molecular weights via ATRP . ATRP of MMA with the resulting block copolymers composed of PIB and PPEGMA chain segments led t o the desired block copolymers with high initiating efficiency. Investigations of the resulting pentablock copolymers by DSC, SAXS and phase mode AFM revealed that nanophase separation occurs in these new macromolecular structures with average domain dista nces of 11 - 14 nm, and local lamellar self - assembly takes place in the pentablocks with PPEGMA polymacromonomer segments of PEGMAs with M n of 118 g/mol and 300 g/mol , while disordered nanophases are observed in the block copolymer with PEGMA having molecula r weight of 475 g/mol. These new amphiphilic block copolymers composed of biocompatible chain segments can find applications in a variety of advanced fields

On the Navier-Stokes equations with rotating effect and prescribed outflow velocity

We consider the equations of Navier-Stokes modeling viscous fluid flow past a moving or rotating obstacle in $\mathbb{R}^d$ subject to a prescribed velocity condition at infinity. In contrast to previously known results, where the prescribed velocity vector is assumed to be parallel to the axis of rotation, in this paper we are interested in a general outflow velocity. In order to use $L^p$-techniques we introduce a new coordinate system, in which we obtain a non-autonomous partial differential equation with an unbounded drift term. We prove that the linearized problem in $\mathbb{R}^d$ is solved by an evolution system on $L^p_{\sigma}(\mathbb{R}^d)$ for $1<p<\infty$. For this we use results about time-dependent Ornstein-Uhlenbeck operators. Finally, we prove, for $p\geq d$ and initial data $u_0\in L^p_{\sigma}(\mathbb{R}^d)$, the existence of a unique mild solution to the full Navier-Stokes system.Comment: 18 pages, to appear in J. Math. Fluid Mech. (published online first

Direct measurements of the energy flux due to chemical reactions at the surface of a silicon sample interacting with a SF6 plasma

Energy exchanges due to chemical reactions between a silicon surface and a SF6 plasma were directly measured using a heat flux microsensor (HFM). The energy flux evolution was compared with those obtained when only few reactions occur at the surface to show the part of chemical reactions. At 800 W, the measured energy flux due to chemical reactions is estimated at about 7 W.cm\^{-2} against 0.4 W.cm\^{-2} for ion bombardment and other contributions. Time evolution of the HFM signal is also studied. The molar enthalpy of the reaction giving SiF4 molecules was evaluated and is consistent with values given in literature.Comment: 3 page

Weight‐of‐Evidence Approach for Assessing Removal of Metals from the Water Column for Chronic Environmental Hazard Classification

The United Nations and the European Union have developed guidelines for the assessment of long‐term (chronic) chemical environmental hazards. This approach recognizes that these hazards are often related to spillage of chemicals into freshwater environments. The goal of the present study was to examine the concept of metal ion removal from the water column in the context of hazard assessment and classification. We propose a weight‐of‐evidence approach that assesses several aspects of metals including the intrinsic properties of metals, the rate at which metals bind to particles in the water column and settle, the transformation of metals to nonavailable and nontoxic forms, and the potential for remobilization of metals from sediment. We developed a test method to quantify metal removal in aqueous systems: the extended transformation/dissolution protocol (T/DP‐E). The method is based on that of the Organisation for Economic Co‐operation and Development (OECD). The key element of the protocol extension is the addition of substrate particles (as found in nature), allowing the removal processes to occur. The present study focused on extending this test to support the assessment of metal removal from aqueous systems, equivalent to the concept of “degradability” for organic chemicals. Although the technical aspects of our proposed method are different from the OECD method for organics, its use for hazard classification is equivalent. Models were developed providing mechanistic insight into processes occurring during the T/DP‐E method. Some metals, such as copper, rapidly decreased (within 96 h) under the 70% threshold criterion, whereas others, such as strontium, did not. A variety of method variables were evaluated and optimized to allow for a reproducible, realistic hazard classification method that mimics reasonable worst‐case scenarios. We propose that this method be standardized for OECD hazard classification via round robin (ring) testing to ascertain its intra‐ and interlaboratory variability. Environ Toxicol Chem 2019;38:1839–1849. © 2019 SETAC.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151334/1/etc4470_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151334/2/etc4470.pd

Angle-dependent normalization of neutron-proton differential cross sections

Systematic errors in the database of $np$ differential cross sections below 350 MeV are studied. By applying angle-dependent normalizations with the help of the energy-dependent Nijmegen partial-wave analysis PWA93 the $\chi^2$-values of some seriously flawed data sets can be reduced significantly at the expense of a few degrees of freedom. It turns out that in these special cases the renormalized data sets can be made statistically acceptable such that they do not have to be discarded any longer in partial-wave analyses of the two-nucleon scattering data.Comment: 11 pages, 1 figure; expanded versio

KAM for the quantum harmonic oscillator

In this paper we prove an abstract KAM theorem for infinite dimensional Hamiltonians systems. This result extends previous works of S.B. Kuksin and J. P\"oschel and uses recent techniques of H. Eliasson and S.B. Kuksin. As an application we show that some 1D nonlinear Schr\"odinger equations with harmonic potential admits many quasi-periodic solutions. In a second application we prove the reducibility of the 1D Schr\"odinger equations with the harmonic potential and a quasi periodic in time potential.Comment: 54 pages. To appear in Comm. Math. Phy

Solid polymer fuel cell synthesis by low pressure plasmas: a short review

In this review, we report on the use of low pressure plasmas for elaborating materials at the heart of solid polymer fuel cells (SPFC), especially electrodes and the membrane electrolyte. Electrodes are formed using plasma sputtering techniques while the ion conducting membranes are built up using plasma polymerization. Fuel cell performance will be improved by these approaches. The electrode catalyst profile is optimized while membrane working temperature is increased and methanol crossover is lowered compared to conventional PEM fuel cells.We gratefully thank GdR 2479 PACEM, Université d'Orléans, SPI-CNRS, ACI ECD 2004 (Ministry of Research) for grants and constant support