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11.
Tadeusz Kosztołowicz Aldona Dutkiewicz 《Mathematical Methods in the Applied Sciences》2020,43(18):10500-10510
We consider three different diffusion processes in a system with a thin membrane: normal diffusion, classical subdiffusion, and slow subdiffusion. We conduct the considerations following the rule: If a diffusion equation is derived from a certain theoretical model, boundary conditions at a thin membrane should also be derived from this model with additional assumptions taking into account selective properties of the membrane. To derive diffusion equations and boundary conditions at a thin membrane, we use a particle random walk model in one-dimensional membrane system in which space and time variables are discrete. Then we move from discrete to continuous variables. We show that the boundary conditions depend on both selective properties of the membrane and a type of diffusion in the system. 相似文献
12.
Poly(vinyl alcohol), pectin and their blends with different components ratio were exposed to low-temperature air plasma or high energy UV-irradiation (λ = 254 nm) for the purpose of surface modification. The physico-chemical changes in surface properties have been studied by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and contact angle measurements. Surface free energy of polymeric films, its polar and dispersive components have been calculated by Owens-Wendt method. Moreover, the work of adhesion was estimated and the recovery of hydrophobic properties of modified films after storage have been also studied.The few seconds air-plasma treatment caused more effective surface modification than 5-6 h UV-irradiation. The observed changes were partially reversible, contrary to these caused by photo-modification.It was found that pectin/PVA (50:50) blend was characterised by larger susceptibility to plasma modification compared to pure pectin and pure PVA, whereas the photosensitivity to radiation of 254 nm wavelength was the lowest for this specimen in comparison to other studied samples. 相似文献
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Detection of 4‐iodo‐2,2‐dimethyloctanenitrile and 2‐iodo‐2‐methylpropanenitrile proved an operation of two types (I and II) of initiation in the I‐ATRA reaction. 4‐Iodo‐2,2‐dimethyloctanenitrile, resulting from the isobutyronitrile radical attack onto 1‐hexene followed by the iodine atom transfer (type II), was formed in reactions of EWG‐CH(R)‐I [R = H, Me; EWG = (EtO)2P(O), (−)−(MenthylO)2 P(O), CN, Br‐C6H4C(O), MeO(O)C, allyl] with 1‐hexene. Nitriles of analogous structures were also detected in reactions of (EtO)2P(O)CH(R)‐I with 1‐heptene, 1‐heptyne, cyclopentene, cyclohexene, and propargyl alcohol. 2‐Iodo‐2‐methylpropanenitrile as the product of the isobutyronitrile attack onto iodine atom of the starting iodide was detected for the first time in the reaction of allyl iodide and 1‐hexene and proved an operation of the cooperating pathway of initiation (type I). EPR experiments, performed directly in the spectrometer cavity, confirmed extremely low concentration of reacting radical species (for a sample of c = 0.1 mol/dm3, <10−8 mol/dm3, or <10−12 moles of spins in a sample) in I‐ATRA reactions involving low reactive 1‐iodoalkylphosphonates. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:246–253, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20116 相似文献
14.
Piotr Bałczewski Tomasz Białas Aldona Szadowiak Marian Mikołajczyk 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1579-1582
The title reaction in the initiation step proceeds via two mechanistic pathways involving attack of the isobutyronitrile radical either on the starting iodide or on the starting alkene or alkyne followed by the reaction of the adduct radical with the iodide. 相似文献
15.
Bartłomiej Kowalczyk Aldona Tarnowska Piotr Tarnowski Janusz Jurczak 《Journal of inclusion phenomena and macrocyclic chemistry》2004,49(1-2):91-95
Eight new chiral macrocyclic bisamides, containing binaphthyl and some other aromatic (phenyl or naphthyl) subunits, are obtained in racemic form. Preliminary results concerning their ability for complexation of alkali metal cations, using ESI-MS technique, are presented. 相似文献
16.
Aldona Majcher Anna Lewandrowska Franciszek Herold Jacek Stefanowicz Tomasz Słowiński Aleksander P. Mazurek Stefan A. Wieczorek Robert Hołyst 《Analytica chimica acta》2015
We determine the association constants for ligand–protein complex formation using the flow injection method. We carry out the measurements at high flow rates (F = 1 mL min−1) of a carrier phase. Therefore, determination of the association constant takes only a few minutes. Injection of 1 nM of the ligand (10 μL of 1 μM concentration of the ligand solution) is sufficient for a single measurement. This method is tested and verified for a number of complexes of selected drugs (cefaclor, etodolac, sulindac) with albumin (BSA). We obtain K = 4.45 × 103 M−1 for cefaclor, K = 1.00 × 105 M−1 for etodolac and K = 1.03 × 105 M−1 for sulindac in agreement with the literature data. We also determine the association constants of 20 newly synthesized 3β- and 3α-aminotropane derivatives with potential antipsychotic activity – ligands of 5-HT1A, 5-HT2A and D2 receptors with the albumin. Results of the studies reported here indicate that potential antipsychotic drugs bind weakly to the transporter protein (BSA) with K ≈ 102–103 M−1. Our method allows measuring K in a wide range of values (102–109 M−1). This range depends only on the solubility of the ligand and sensitivity of the detector. 相似文献
17.
Aldona Kostuch Iwona A. Rutkowska Beata Dembinska Anna Wadas Enrico Negro Keti Vezz Vito Di Noto Pawel J. Kulesza 《Molecules (Basel, Switzerland)》2021,26(17)
Platinum is a main catalyst for the electroreduction of oxygen, a reaction of primary importance to the technology of low-temperature fuel cells. Due to the high cost of platinum, there is a need to significantly lower its loadings at interfaces. However, then O2-reduction often proceeds at a less positive potential, and produces higher amounts of undesirable H2O2-intermediate. Hybrid supports, which utilize metal oxides (e.g., CeO2, WO3, Ta2O5, Nb2O5, and ZrO2), stabilize Pt and carbon nanostructures and diminish their corrosion while exhibiting high activity toward the four-electron (most efficient) reduction in oxygen. Porosity of carbon supports facilitates dispersion and stability of Pt nanoparticles. Alternatively, the Pt-based bi- and multi-metallic catalysts, including PtM alloys or M-core/Pt-shell nanostructures, where M stands for certain transition metals (e.g., Au, Co, Cu, Ni, and Fe), can be considered. The catalytic efficiency depends on geometric (decrease in Pt–Pt bond distances) and electronic (increase in d-electron vacancy in Pt) factors, in addition to possible metal–support interactions and interfacial structural changes affecting adsorption and activation of O2-molecules. Despite the stabilization of carbons, doping with heteroatoms, such as sulfur, nitrogen, phosphorus, and boron results in the formation of catalytically active centers. Thus, the useful catalysts are likely to be multi-component and multi-functional. 相似文献
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The X-band EPR study of a polycrystalline Cs2Cu(ZrF6)2*6H2O demonstrates a feature of plasticity of the Jahn-Teller Cu(H2O)6 complex in the crystal lattice of this compound. The temperature- and pressure-induced evolution of the spectra shows that the copper complex is extremely sensitive to these factors, which due to the ferroelastic properties of the compound studied modify the internal tetragonal and orthorhombic strains acting on the complex. It is supported by the analysis of the temperature dependencies of the principal values of the g-factor under various pressures, indicating that the complex varies its shape adapting it to the varied conditions. A pressure-induced phase transition is discovered. 相似文献
20.
Sashchiuk Aldona Lifshitz Efrat Reisfeld Renata Saraidarov Tsiala Zelner Marina Willenz Avi 《Journal of Sol-Gel Science and Technology》2002,24(1):31-38
Lead sulfide (PbS) nanocrystals (NCs), embedded in amorphous zirconia sol-gel film with different PbS mole concentration (5–30%), were grown at temperature, ranging from 200°C to 350°C. The size of PbS NCs was determined by TEM and by blue shift of the absorption edge. The size increased with an increase of the synthesis temperature and PbS mole concentration. The optical and electrical properties of various sizes of PbS NCs in zirconia film are investigated utilizing absorption, photoluminescence (PL) and current-voltage measurement. The PL spectra were Stokes shifted from the corresponding absorption edge by about 0.5 eV. The latter can be associated with recombination process from surface state. The electrical properties were investigated by the deposition of the PbS NCs-zirconia films on ITO/glass substrate, followed by their coverage with gold contact. The current-voltage characteristics depend on the PbS NCs size and exhibits nonlinear nearly symmetric curve, associated with the space-charge limited current or the tunneling of carriers through the nanocrystalline film. 相似文献