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61.
In this study, we show that the inclusion of a short-range part of the total attractive interaction into a reference system allows a natural extension of the traditional first-order perturbation theory of simple fluids to practically all thermodynamic states. This theory is applied to the thermodynamic functions and the liquid–vapor coexistence curve of the Lennard-Jones-like medium range Yukawa fluid and to the Sutherland fluid. Comparison with computer simulation data and the second-order Barker–Henderson perturbation theory is discussed. 相似文献
62.
Jessica Hain Andrij Pich Hans-Jürgen Adler David Rais Stanislav Nešpůrek 《Macromolecular Symposia》2008,268(1):61-65
Summary : Novel polymeric particles of spherical shape consisting of an electrically insulating poly(styrene-co-acetoacetoxyethyl methacrylate) (PS/PAAEM) core and a conductive shell of poly(3,4-ethylenedioxythiophene) (PEDOT) were synthesized. Electric measurements showed a strong dependence of the conductivity on weight ratio of PEDOT to PS/PAAEM in the composite. As the PEDOT content varied from 2 to 31.4 wt.-%, resistivity of the resulting material changed exponentially from 12 GΩ cm to 100 Ω cm, depending also on the type of the used oxidation agent. Similar studies were performed on the basis of insulating poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate) (PVCL/PAAEM) microgel particles, which acted as microreactors for the synthesis of conductive PEDOT nanorods. In microgel systems, the conductivity was lower than in core-shell systems, when the PEDOT content was less than 5 wt.-%. Above this value of PEDOT concentration, the conductivities in the two systems became similar. 相似文献
63.
We report how the linewidth and line shape of a tunable semiconductor-optical-amplifier-based fiber ring laser can be actively adjusted by applying an intracavity frequency modulation to the laser. Frequency-modulated laser operation is achieved by driving the phase modulator frequency close to the cavity axial-mode spacing, leading to a constant-amplitude laser output having a periodically varying instantaneous frequency. The resulting linewidth varies proportionally with the inverse of the frequency detuning, and it is adjustable from submegahertz to over more than 5 GHz. By appropriate selection of the modulating waveform we have synthesized a near-Gaussian output line shape; other line shapes can be produced by modifying the modulating waveform. Experimental observations are in good agreement with a simple model. 相似文献
64.
65.
Bernstein SL Wyttenbach T Baumketner A Shea JE Bitan G Teplow DB Bowers MT 《Journal of the American Chemical Society》2005,127(7):2075-2084
The amyloid beta-protein (Abeta) is a seminal neuropathic agent in Alzheimer's disease (AD). Recent evidence points to soluble Abeta oligomers as the probable neurotoxic species. Among the naturally occurring Abeta peptides, the 42-residue form Abeta42 is linked particularly strongly with AD, even though it is produced at approximately 10% of the levels of the more abundant 40-residue form Abeta40. Here, we apply mass spectrometry and ion mobility to the study of Abeta42 and its Pro19 alloform. The Phe19 --> Pro19 substitution blocks fibril formation by [Pro19]Abeta42. Evidence indicates that solution-like structures of Abeta monomers are electrosprayed and characterized. Unfiltered solutions of Abeta42 produce only monomers and large oligomers, whereas [Pro19]Abeta42 solutions produce abundant monomers, dimers, trimers, and tetramers but no large oligomers. When passed through a 10,000 amu filter and immediately sampled, Abeta42 solutions produce monomers, dimers, tetramers, hexamers, and an aggregate of two hexamers that may be the first step in protofibril formation. These results are consistent with recently published photochemical cross-linking data and lend support to recent aggregation mechanisms proposed by Bitan, Teplow, and co-workers [J. Biol. Chem. 2003, 278, 34882-34889]. 相似文献
66.
Ján Pich 《Mathematical Logic Quarterly》2011,57(4):379-383
We prove that the Nisan‐Wigderson generators based on computationally hard functions and suitable matrices are hard for propositional proof systems that admit feasible interpolation. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
67.
Wenjing Xu Dr. Andrey Rudov Alex Oppermann Sarah Wypysek Michael Kather Dr. Ricarda Schroeder Prof. Walter Richtering Prof. Igor I. Potemkin Prof. Dominik Wöll Prof. Andrij Pich 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(3):1264-1271
Controlling the distribution of ionizable groups of opposite charge in microgels is an extremely challenging task, which could open new pathways to design a new generation of stimuli-responsive colloids. Herein, we report a straightforward approach for the synthesis of polyampholyte Janus-like microgels, where ionizable groups of opposite charge are located on different sides of the colloidal network. This synthesis approach is based on the controlled self-assembly of growing polyelectrolyte microgel precursors during the precipitation polymerization process. We confirmed the morphology of polyampholyte Janus-like microgels and demonstrate that they are capable of responding quickly to changes in both pH and temperature in aqueous solutions. 相似文献
68.
M. Jamin J.A. Oller A. Pich 《The European Physical Journal C - Particles and Fields》2002,24(2):237-243
In this work, the mass of the strange quark is calculated from QCD sum rules for the divergence of the strangeness-changing
vector current. The phenomenological scalar spectral function which enters the sum rule is determined from our previous work
on strangeness-changing scalar form factors [1]. For the running strange mass in the scheme, we find . Making use of this result and the light quark mass ratios obtained from chiral perturbation theory, we are also able to
extract the masses of the lighter quarks and . We then obtain and . In addition, we present an updated value for the light quark condensate.
Received: 18 October 2001 / Revised version: 22 January 2002 / Published online: 12 April 2002 相似文献
69.
Aqueous microgels for the growth of hydroxyapatite nanocrystals 总被引:1,自引:0,他引:1
Schachschal S Pich A Adler HJ 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):5129-5134
In present article, we demonstrate that aqueous microgels can be used as containers for the in-situ synthesis of hydroxyapatite. The hydroxyapatite nanocrystals (HAp NCs) become integrated into microgels forming hybrid colloids. The HAp NCs loaded in the microgel can be varied over a broad range. The HAp NCs are localized within the microgel corona. The deposition of the inorganic nanocrystals decreases the colloidal stability of the microgels and leads to particle aggregation at high HAp NCs loading. Because of the strong interactions between HAp NCs and polymer chains, the swelling degree of microgels decreases, and temperature-sensitive properties disappear at high loading of the inorganic component. We demonstrate that hybrid colloids can be used as building blocks for the preparation of nanostructured films on solid substrates. 相似文献
70.
Poly(N‐vinylcaprolactam)‐based biodegradable microgels are prepared for drug delivery application via precipitation polymerization using diacetone acrylamide (DAAM) and dimethyl itaconate (IADME) as comonomers. The microgel particles are subsequently crosslinked by addition of adipic acid dihydrazide, which reacts with the ketone groups of DAAM. Itaconic acid (IA) groups are generated by the hydrolysis of IADME units inside the microgels resulting into both pH and temperature sensitive microgel particles. Volume phase transition temperature of the obtained microgels is influenced by both IA content and pH of the surrounding medium. Due to the incorporation of hydrazone linkages, the microgels show degradation under acidic conditions. These microgels can effectively encapsulate doxorubicin (DOX) as a model drug and show low DOX leakage under physiological conditions while rapid DOX release is observed at low pH. The results of the cytotoxicity assay further display that the DOX‐loaded microgels exhibit effective antitumor activity against HeLa cells demonstrating their great potential as drug delivery carriers for cancer therapy. 相似文献