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961.
Charge stabilization improves the numeric performance of double ionization potential equation-of-motion (EOM-DIP) method when using unstable (autoionizing) dianion references. However, the stabilization potential introduces an undesirable perturbation to the target states' energies. Here we introduce and benchmark two approaches for removing the perturbation caused by the stabilization. The benchmark calculations of excitation energies in selected diradicals illustrate that the so-called core correction based on evaluating the perturbation in a small basis set is robust and yields reliable EOM-DIP values, i.e., the errors of 0.0-0.3 eV against a similar-level coupled-cluster approach. 相似文献
962.
Katalin Bocz Andrea Toldy Ákos KmettyTamás Bárány Tamás IgriczGyörgy Marosi 《Polymer Degradation and Stability》2012,97(3):221-227
Multilayered self-reinforced composites were developed from a density-separated light fraction of automotive shredder waste of high polyolefin content, which can fulfil the current technical, safety and environmental requirements of structural materials. The significantly enhanced mechanical properties of the recycled composites were ensured by polypropylene fabric reinforcement; meanwhile, reduced flammability was obtained by modifying the matrix layers, made of secondary raw materials, with phosphorous-containing flame retardant additive. The results of the new flame retarded composite systems allowed the discussion of a novel mechanistic observation. The mechanical and flammability properties of the prepared self-reinforced composites are compared to conventional glass fabric reinforced composites and to compounds without reinforcement. 相似文献
963.
Origins of thermodynamically stable superhydrophobicity of boron nitride nanotubes coatings 总被引:1,自引:0,他引:1
Boinovich LB Emelyanenko AM Pashinin AS Lee CH Drelich J Yap YK 《Langmuir : the ACS journal of surfaces and colloids》2012,28(2):1206-1216
Superhydrophobic surfaces are attractive as self-cleaning protective coatings in harsh environments with extreme temperatures and pH levels. Hexagonal phase boron nitride (h-BN) films are promising protective coatings due to their extraordinary chemical and thermal stability. However, their high surface energy makes them hydrophilic and thus not applicable as water repelling coatings. Our recent discovery on the superhydrophobicity of boron nitride nanotubes (BNNTs) is thus contradicting with the fact that BN materials would not be hydrophobic. To resolve this contradiction, we have investigated BNNT coatings by time-dependent contact angle measurement, thermogravimetry, IR spectroscopy, and electron microscopy. We found that the wettability of BNNTs is determined by the packing density, orientation, length of nanotubes, and the environmental condition. The origins of superhydrophobicity of these BNNT coatings are identified as (1) surface morphology and (2) hydrocarbon adsorbates on BNNTs. Hydrocarbon molecules adsorb spontaneously on the curved surfaces of nanotubes more intensively than on flat surfaces of BN films. This means the surface energy of BNNTs was enhanced by their large curvatures and thus increased the affinity of BNNTs to adsorb airborne molecules, which in turn would reduce the surface energy of BNNTs and make them hydrophobic. Our study revealed that both high-temperature and UV-ozone treatments can remove these adsorbates and lead to restitution of hydrophilic BN surface. However, nanotubes have a unique capability in building a hydrophobic layer of adsorbates after a few hours of exposure to ambient air. 相似文献
964.
Krzysztof R. Idzik Tobias Licha Vladimír Lukeš Peter Rapta Jaroslaw Frydel Mario Schaffer Eric Taeuscher Rainer Beckert Lothar Dunsch 《Journal of fluorescence》2014,24(1):153-160
A series of various thienyl derivatives of pyrene were synthesized by Stille cross-coupling procedure. Their structures were characterized by 1H NMR, 13C NMR and elemental analysis. The spectroscopic characteristics were investigated by UV–vis absorption and fluorescence spectra. Based on quantum chemical calculations, the energy levels of investigated molecules with respect to the pyrene molecule were also discussed. 相似文献
965.
Mahdi Hormozi Franciszek Prus-Wiśniowski Hjalmar Rosengren 《Journal of Mathematical Analysis and Applications》2014
The characterization of the inclusion of Waterman–Shiba spaces ΛBV(p) into generalized Wiener classes of functions BV(q;δ) is given. It uses a new and shorter proof and extends an earlier result of U. Goginava. 相似文献
966.
967.
Critical micellear concentrations (CMC) were determined for two novel promoters of membrane permeability—7-monoketocholic acid (7-MKC) and 12-monoketocholic acid (12-MKC), using two non-invasive (1H NMR relaxation experiment and conductometry) and two invasive (spectral shift and partition coefficient of the probe molecule) methods. Studies by the former methods suggest the different aggregation abilities of the investigated bile acid derivatives. In an aqueous solution, 7-MKC has a somewhat lower CMC value (43 mM) than 12-MKC (50 mM). Further, it was found that, in addition to primary micelles, 7-MKC forms also secondary micelles. In the experiments with probe (hydrophobic) molecules, the aggregation properties of investigated bile acids did not differ in water, whereas the presence of urea altered the aggregation of 7-MKC.Based on the CMC value, 7-MKC is more hydrophobic than 12-MKC. The apparent hydrophobicity of 7-MKC is a consequence of the formation of secondary micelles, shifting the monomer equilibrium to the direction of primary micelles, which is manifested as a decrease in the CMC value. 相似文献
968.
P. Pasierb Ewa Drożdż-Cieśla R. Gajerski S. Łabuś S. Komornicki M. Rękas 《Journal of Thermal Analysis and Calorimetry》2009,96(2):475-480
The purpose of this work was to investigate the influence of titanium and yttrium dopants on chemical stability of selected
Ba(Ce1−xTix)1−yYyO3 compounds. The presented results are the part of wider research concerning the crystallographic structure, microstructure,
electrical and transport properties of these groups of materials.
Samples of Ba(Ce1−xTix)1−yYyO3 with x=0.05, 0.07, 0.10, 0.15, 0.20, 0.30 and y=0.05, 0.10, 0.20 (for x=0.05) were prepared by solid-state reaction method. Initially, differential thermal analysis (DTA) and thermogravimetry (TG)
were used for optimization of preparation conditions. Subsequently, DTA-TG-MS (mass spectrometry) techniques were applied
for evaluation of the stability of prepared materials in the presence of CO2. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results were used to determine the phase composition,
structure and microstructure of materials and to assist the interpretation of DTA-TG-MS results.
The strong influence of Ti and Y dopants contents (x and y) on the properties was found. The introduction of Ti dopant led to the improvement of chemical stability against CO2. The lower Ti concentration the better resistance against CO2 corrosion was observed. Doping by Y had the opposite effect; the decrease of chemical stability was determined. In this case
the higher Y dopant concentration the better resistance was observed. The attempt to correlate the influence of dopant on
structure and chemical stability was also presented. 相似文献
969.
Reprocessability and melting behaviour of self-reinforced composites based on PP homo and copolymers
Tamás Bárány András Izer Alfréd Menyhárd 《Journal of Thermal Analysis and Calorimetry》2010,101(1):255-263
In our present study, the reprocessability of a self-reinforced PP composites (SRPPC) prepared by compression molding was
studied. The composite materials (handled separately, based on the related matrix material) were ground, then extruded five
times and injection molded after the first and fifth cycle in order to investigate the behaviour of the material during reprocessing.
As a reference, the matrices of the composites were also reprocessed and injection molded similarly to the composites. On
the manufactured specimens, static (tensile and flexural) and dynamic mechanical tests (Charpy) were performed. The melting
and crystalline characteristics were studied by Differential Scanning Calorimetry (DSC). The probable decomposition caused
by multiple extrusions was followed by the Melt Volume Rate (MVR). The results indicated that in case of commercial materials
there is no significant degradation even after multiple reprocessing cycles; therefore, the reprocessability of SRPPC products
has no hindrance. The presence of α-iPP reinforcement in the rPP-based composites after reprocessing results in increased
inclination for crystallization and consequently leads to improved mechanical stiffness compared to rPP neat matrices. 相似文献
970.
Agnieszka Wojciechowska Marek Daszkiewicz Zbigniew Staszak Magdalena Boczar Julia Jezierska Maria Cieślak-Golonka 《Structural chemistry》2010,21(2):337-345
Novel copper(II) complex of the formula [Cu(phen)2OCrO3](phen)0.5
·4H2O (1) (phen = 1,10-phenantroline) was prepared in the crystalline form and characterized by X-ray diffraction and spectroscopic
methods (IR-FIR, NIR-Vis–UV, EPR). In the solid state, the CuN4O chromophore adopts a slightly distorted square-pyramidal geometry around the Cu2+ ion with a magnitude of a distortion parameter τ = 0.14. The chromate unit in (1) was found to be a monodentate. 相似文献