Boundary-induced heterogeneous absorbing states

We study two different types of systems with many absorbing states (with and without a conservation law) and scrutinize the effect of walls/boundaries (either absorbing or reflecting) into them. In some cases, non-trivial structured absorbing configurations (characterized by a background field) develop around the wall. We study such structures using a mean-field approach as well as computer simulations. The main results are: i) for systems in the directed percolation class, a very fast (exponential) convergence of the background to its bulk value is observed; ii) for systems with a conservation law, power-law decaying landscapes are induced by both types of walls: while for absorbing walls this effect is already present in the mean-field approximation, for reflecting walls the structured background is a noise-induced effect. The landscapes are shown to converge to their asymptotic bulk values with an exponent equal to the inverse of the bulk correlation length exponent. Finally, the implications of these results in the context of self-organizing systems are discussed.Comment: 8 pages, 2 figure

Prompt and nonprompt ψ (2S) production in pPb collisions at √sNN = 8. 16 TeV

The production of ψ(2S) mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of √sNN = 8.16 TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb−1. The prompt and nonprompt ψ(2S) production cross-sections and the ratio of the ψ(2S) to J/ψ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt ψ(2S) is observed to be more suppressed compared to pp collisions than the prompt J/ψ production, while the nonprompt productions have similar suppression factors

Calix[4]arenes of Aluminum and Gallium with Benzimidazolyl Ligands: Steric Control of the Conformation via Substitution on the Ligand

Complexes [bzimAlR₂]₄ [bzim = benzimidazolate; R = Et (<b>2</b>), ^<i>i</i>Bu (<b>3</b>)], [mbzimAlR₂]₄ [mbzim = 2-methylbenzimidazolate; R = Et (<b>6</b>), ^<i>i</i>Bu (<b>7</b>)], [dmbzimAlR₂]₄ [dmbzim = 5,6-dimethylbenzimidazolate; R = Me (<b>9</b>), Et (<b>10</b>), ^<i>i</i>Bu (<b>11</b>)], and [tmbzimAlR₂]₄ [tmbzim = 2,5,6-trimethylbenzimidazolate; R = Me (<b>12</b>), Et (<b>13</b>), ^<i>i</i>Bu (<b>14</b>)] have been prepared via alkane elimination and coordinative self-assembly upon the reaction of benzimidazole ligands with aluminum alkyls in benzene, toluene, or xylene. Characterization of the complexes was achieved by spectroscopic methods, microanalysis, and X-ray crystallography of <b>2</b>, <b>7</b>, <b>10</b>, <b>11</b>, <b>13</b>, and <b>14</b>. The complexes reported herein and the aluminum and gallium analogues <b>1</b>, <b>4</b>, <b>5</b>, and <b>8</b> reported in a previous paper are predominantly tetranuclear aggregates related to calix[4]­arenes in which the benzimidazolyl ligands bind two metal atoms in a η¹:η¹ fashion. X-ray crystallography demonstrates that modulation of the conformation adopted by these metallacalix[4]­arenes is achieved by proper substitution on the C atom at the 2 position of the benzimidazolyl ligand. An H substituent for <b>1</b>, <b>2</b>, <b>4</b>, <b>10</b>, and <b>11</b> favors a chair conformation with a small cavity and approximate <i>C</i>_2<i>h</i> symmetry, while a CH₃ substituent for <b>5</b>, <b>7</b>, <b>8</b>, <b>13</b>, and <b>14</b> introduces enough repulsion to switch the conformation to a 1,3-alternate or double cone with a concomitant larger cavity and approximate <i>C</i>_2<i>v</i> symmetry

Mobbning inom skolan - förebyggnad samt åtgärder

Syftet med mitt examensarbete är att lyfta fram vad mobbning innebär. Vad är det som definierar mobbning, vilka utformningar den kan ha och varför det bara är vissa som blir mobbade. Min avsikt är även den att lyfta fram skolans ansvar gentemot mobbning. Hur kan man arbeta förebyggande samt vilka åtgärder finns det i skolan mot mobbning. Mina tre frågeställningar i mitt arbete är följande: – Vad är mobbning? – Hur kan mobbning förebyggas i skola? – Vilka åtgärder inom skolan finns mot mobbning? Som hjälp till mitt arbete har jag använt mig av relevant fakta och litteratur. Undersökningen och insamlingen av mitt empiriska material har utförts på en mellanstor f-9 skola i en rätt så stor kommun. Min undersökning utgjordes av två intervjuer i en klass 2 där jag delade upp klassen i pojkar och flickor. Andra metoder jag använt mig av är att jag var med på ett av skolans antimobbningsmöte samt stämde mötet med en av skolans fritidspedagoger som jag hade ett givande samtal med. Jag har genom min undersökning konstaterat att de som verkar inom skolan har stort ansvar och betydelse i arbetet att förhindra och motverka mobbning

Calix[4]arenes of Aluminum and Gallium with Benzimidazolyl Ligands: Steric Control of the Conformation via Substitution on the Ligand

Complexes [bzimAlR₂]₄ [bzim = benzimidazolate; R = Et (<b>2</b>), ^<i>i</i>Bu (<b>3</b>)], [mbzimAlR₂]₄ [mbzim = 2-methylbenzimidazolate; R = Et (<b>6</b>), ^<i>i</i>Bu (<b>7</b>)], [dmbzimAlR₂]₄ [dmbzim = 5,6-dimethylbenzimidazolate; R = Me (<b>9</b>), Et (<b>10</b>), ^<i>i</i>Bu (<b>11</b>)], and [tmbzimAlR₂]₄ [tmbzim = 2,5,6-trimethylbenzimidazolate; R = Me (<b>12</b>), Et (<b>13</b>), ^<i>i</i>Bu (<b>14</b>)] have been prepared via alkane elimination and coordinative self-assembly upon the reaction of benzimidazole ligands with aluminum alkyls in benzene, toluene, or xylene. Characterization of the complexes was achieved by spectroscopic methods, microanalysis, and X-ray crystallography of <b>2</b>, <b>7</b>, <b>10</b>, <b>11</b>, <b>13</b>, and <b>14</b>. The complexes reported herein and the aluminum and gallium analogues <b>1</b>, <b>4</b>, <b>5</b>, and <b>8</b> reported in a previous paper are predominantly tetranuclear aggregates related to calix[4]­arenes in which the benzimidazolyl ligands bind two metal atoms in a η¹:η¹ fashion. X-ray crystallography demonstrates that modulation of the conformation adopted by these metallacalix[4]­arenes is achieved by proper substitution on the C atom at the 2 position of the benzimidazolyl ligand. An H substituent for <b>1</b>, <b>2</b>, <b>4</b>, <b>10</b>, and <b>11</b> favors a chair conformation with a small cavity and approximate <i>C</i>_2<i>h</i> symmetry, while a CH₃ substituent for <b>5</b>, <b>7</b>, <b>8</b>, <b>13</b>, and <b>14</b> introduces enough repulsion to switch the conformation to a 1,3-alternate or double cone with a concomitant larger cavity and approximate <i>C</i>_2<i>v</i> symmetry

The Gold(I)- and Silver(I)-Catalyzed Nicholas Reaction

The Au­(I) and Ag­(I) catalytic Nicholas type reaction has been developed for oxygen and carbon nucleophiles. This process occurs with high reaction yields and selectivity, avoiding the main shortcomings of the acid-promoted standard Nicholas reaction. A catalytic reaction pathway involving trimetallic complex intermediates is proposed

Composition and Evolution of the Solid-Electrolyte Interphase in Na₂Ti₃O₇ Electrodes for Na-Ion Batteries: XPS and Auger Parameter Analysis

Na₂Ti₃O₇ is considered a promising negative electrode for Na-ion batteries; however, poor capacity retention has been reported and the stability of the solid-electrolyte interphase (SEI) could be one of the main actors of this underperformance. The composition and evolution of the SEI in Na₂Ti₃O₇ electrodes is hereby studied by means of X-ray photoelectron spectroscopy (XPS). To overcome typical XPS limitations in the photoelectron energy assignments, the analysis of the Auger parameter is here proposed for the first time in battery materials characterization. We have found that the electrode/electrolyte interface formed upon discharge, mostly composed by carbonates and semicarbonates (Na₂CO₃, NaCO₃R), fluorides (NaF), chlorides (NaCl) and poly­(ethylene oxide)­s, is unstable upon electrochemical cycling. Additionally, solid state nuclear magnetic resonance (NMR) studies prove the reaction of the polyvinylidene difluoride (PVdF) binder with sodium. The powerful approach used in this work, namely Auger parameter study, enables us to correctly determine the composition of the electrode surface layer without any interference from surface charging or absolute binding energy calibration effects. As a result, the suitability for Na-ion batteries of binders and electrolytes widely used for Li-ion batteries is questioned here

Stabilization of Trans Disilyl Coordination at Square-Planar Platinum Complexes

By using two different multidentate phosphinosilyl ligands, we prepared the two platinum complexes [Pt­{PhP­((<i>o</i>-C₆H₄)­CH₂SiMe₂)₂}­PPh₃] (<b>3</b>) and [Pt­{P­((<i>o</i>-C₆H₄)­CH₂SiMe₂)₂(<i>o</i>-C₆H₄)­CHSiMe₂)}­PPh₃] (<b>4</b>) exhibiting a trans configuration of the silicon atoms in a typical square-planar geometry around a Pt­(II) center. Complex <b>4</b> results from intramolecular C–H activation of a methylene moiety by the third silicon atom of the original ligand and displays an anagostic C–H···Pt interaction, as supported by solution NMR data and solid-state X-ray diffraction analysis. The reactivity of <b>3</b> toward small molecules is also discussed. In the case of H₂ and CO, the corresponding dihydride [PtH₂{PhP­((<i>o</i>-C₆H₄)­CH₂SiMe₂)₂}­PPh₃] (<b>5</b>) and dicarbonyl [Pt­{PhP­((<i>o</i>-C₆H₄)­CH₂SiMe₂)₂}­(CO)₂] (<b>6</b>) complexes were characterized, whereas reduction to Pt(0) and release of PPh₃ and HSiMe₃ were observed upon thermolysis in the presence of HBpin