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201.
Meingast C Hardy F Heid R Adelmann P Böhmer A Burger P Ernst D Fromknecht R Schweiss P Wolf T 《Physical review letters》2012,108(17):177004
Thermal expansion data are used to study the uniaxial pressure dependence of the electronic-magnetic entropy of Ba(Fe(1-x)Co(x))2As2. Uniaxial pressure is found to be proportional to doping and, thus, also an appropriate tuning parameter in this system. Many of the features predicted to occur for a pressure-tuned quantum critical system, in which superconductivity is an emergent phase hiding the critical point, are observed. The electronic-magnetic Grüneisen parameters associated with the spin-density wave and superconducting transitions further demonstrate an intimate connection between both ordering phenomena. 相似文献
202.
J Alliot E Gravel F Pillon DA Buisson M Nicolas E Doris 《Chemical communications (Cambridge, England)》2012,48(65):8111-8113
A novel approach for the asymmetric synthesis of the active (1S,2R)-enantiomer of the antidepressant milnacipran is reported. The two stereogenic centers borne by the cyclopropane ring were sequentially installed starting from phenylacetic acid. 相似文献
203.
204.
In the present work the complex process of diffusion-controlled wet chemical etching of a rotating silicon wafer is analyzed in the framework of an unsteady integral boundary layer approximation. The obtained results reproduce the waviness and the associated enhancement of the mass transfer in the wavy region, and are in good agreement with experimental findings. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
205.
206.
Ronald Zirbs Wolfgang Binder Markus Gahleitner Doris Machl 《Macromolecular Symposia》2007,254(1):93-96
Summary: This publication discusses the development of new methods for producing organic-inorganic core-shell-nanoparticles (NP's) via a combination of “grafting-from” techniques and living cationic polymerization reactions. Based on the surface initiated, quasiliving cationic polymerization of isobutylene, polymeric shells of polyisobutylene (PIB) were attached onto nanoparticles (silica NP's of different sizes, r = 12–40 nm) with a high degree of precision. “Grafting-from” polymerization provides an ideal method to control the number of polymer chains per particle by means of the degree of initial derivatization and the length of the polymeric chains. The resulting nanocomposite materials were analyzed using DLS, TEM, GPC, TGA, DSC. 相似文献
207.
Supersonic turbulence is a main agent for structure formation in space, from stellar winds to wind-blown bubbles, supernovae remnants, -ray bursts, and star-formation in molecular clouds. Dissipation is mostly due to shocks. Under isothermal conditions, the density follows a log-normal distribution whose variance grows with Mach number. The exact scaling is under debate. We focus on problems with not strictly periodic boundary conditions and present 2D and 3D numerical simulation of supersonic turbulence in plan-parallel slabs. From dimensional analysis we derive scaling laws for the mean quantities under isothermal conditions. Simulations including spatially extended radiative cooling layers reveal a complex interplay between turbulence and RM- and RT-unstable interfaces. Turbulent Mach numbers here are significantly reduced compared to the isothermal case and are of order 1. However, unstable interfaces between the different thermal component of the gas are equally able to produce structure. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
208.
Svetlana Tretsiakova-McNally Aloshy Baby Paul Joseph Doris Pospiech Eileen Schierz Albena Lederer Malavika Arun Gaëlle Fontaine 《Molecules (Basel, Switzerland)》2023,28(1)
Polystyrene (PS) was modified by covalently binding P-, P-N- and/or N- containing fire-retardant moieties through co- or ter-polymerization reactions of styrene with diethyl(acryloyloxymethyl)phosphonate (DEAMP), diethyl-p-vinylbenzyl phosphonate (DEpVBP), acrylic acid-2-[(diethoxyphosphoryl)methylamino]ethyl ester (ADEPMAE) and maleimide (MI). In the present study, the condensed-phase and the gaseous-phase activities of the abovementioned fire retardants within the prepared co- and ter-polymers were evaluated for the first time. Pyrolysis–Gas Chromatography/Mass Spectrometry was employed to identify the volatile products formed during the thermal decomposition of the modified polymers. Benzaldehyde, α-methylstyrene, acetophenone, triethyl phosphate and styrene (monomer, dimer and trimer) were detected in the gaseous phase following the thermal cracking of fire-retardant groups and through main chain scissions. In the case of PS modified with ADEPMAE, the evolution of pyrolysis gases was suppressed by possible inhibitory actions of triethyl phosphate in the gaseous phase. The reactive modification of PS by simultaneously incorporating P- (DEAMP or DEpVBP) and N- (MI) monomeric units, in the chains of ter-polymers, resulted in a predominantly condensed-phase mode of action owing to synergistic P and N interactions. The solid-state 31P NMR spectroscopy, Scanning Electron Microscopy/Energy Dispersive Spectroscopy, Inductively-Coupled Plasma/Optical Emission Spectroscopy and X-ray Photoelectron Spectroscopy of char residues, obtained from ter-polymers, confirmed the retention of the phosphorus species in their structures. 相似文献
209.
A concise approach for the synthesis of optically active chromenes is reported. The process described herein involves, as the key steps, a Sharpless-epoxidation, a selective deoxygenation, and a ring-closing metathesis. 相似文献
210.