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Irada S. Isayeva Joseph P. Kennedy 《Journal of polymer science. Part A, Polymer chemistry》2004,42(17):4337-4352
This article concerns the synthesis and characterization of novel tricomponent amphiphilic membranes consisting of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) segments cocrosslinked and reinforced by octasilane polyhedral oligomeric silsesquioxane (octasilane‐POSS) cages. Rapid and efficient network synthesis was effected by cocrosslinking diallyl‐telechelic PEG (A‐PEG‐A) and divinyl‐telechelic PDMS (V‐PDMS‐V) with pentamethylpentacyclosiloxane (D5H), using Karstedt's catalyst in conjunction with Et3N cocatalyst and water. Films were prepared by pouring charges in molds and crosslinking by heating at 60 °C for several hours. The films were characterized by sol fractions and equilibrium swelling both in hexane and water, extent of crosslinking, contact angle hysteresis, oxygen permeability, thermogravimetric analysis, and mechanical properties. The crosslinking of octasilane‐POSS achieved by the same catalyst system was studied in separate experiments. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4337–4352, 2004 相似文献
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Irada S. Isayeva Alan N. Gent Joseph P. Kennedy 《Journal of polymer science. Part A, Polymer chemistry》2002,40(12):2075-2084
A series of amphiphilic hydrogel tubules have been prepared by copolymerizing/crosslinking hydrophilic poly(dimethylacrylamide) segments with hydrophobic di‐, tri‐, and octamethacrylate‐telechelic polyisobutylene crosslinkers, and their elastic modulus and burst strength in the water‐swollen state were investigated. Because the burst characteristics of hydrogels have not yet been quantitatively investigated, equipment was designed and built to generate fundamental insight into the burst properties of thin‐walled (200–250 μm) narrow lumen (2–3 mm i.d.) water‐swollen tubules. The theory developed to describe quantitatively the inflation behavior of thin‐walled rubber tubules was adapted to treat our experimental observations. Changes in the burst strength, elastic modulus, and expansion during the inflation of hydrogel tubules were interpreted in terms of the molecular weight of the hydrophilic segments between crosslinking sites (Mc,hydrophilic), which in turn was calculated according to the rubber elasticity theory. According to these investigations, the burst strength of our water‐swollen amphiphilic tubules is in the 0.2–0.5 MPa range, which is sufficient for implantation and immunoisolatory applications. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2075–2084, 2002 相似文献
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H.M. Mahmudov M.K. Ismayilova S.A. Hasanova S.M. Aliyev G.E. Isayeva O.E. Akberov 《辐射效应与固体损伤》2016,171(7-8):630-635
The aim of this study was to investigate the regularities of molecular hydrogen formation from water dispersing Al2O3 nanoparticles irradiated with gamma ray. It was established that formed molecular hydrogen’s yield changed depending on the size of the catalyst, so that yield of molecular hydrogen formed on the surface with small size is 1.4–1.6 times greater than the one with big size. Equal distribution of nanocatalyst in water medium and much more adsorption of water molecule on the catalyst surface result in more efficient radiolysis process. 相似文献
4.
Krasnoshchekov SV Isayeva EV Stepanov NF 《The journal of physical chemistry. A》2012,116(14):3691-3709
Anharmonic vibrational states of semirigid polyatomic molecules are often studied using the second-order vibrational perturbation theory (VPT2). For efficient higher-order analysis, an approach based on the canonical Van Vleck perturbation theory (CVPT), the Watson Hamiltonian and operators of creation and annihilation of vibrational quanta is employed. This method allows analysis of the convergence of perturbation theory and solves a number of theoretical problems of VPT2, e.g., yields anharmonic constants y(ijk), z(ijkl), and allows the reliable evaluation of vibrational IR and Raman anharmonic intensities in the presence of resonances. Darling-Dennison and higher-order resonance coupling coefficients can be reliably evaluated as well. The method is illustrated on classic molecules: water and formaldehyde. A number of theoretical conclusions results, including the necessity of using sextic force field in the fourth order (CVPT4) and the nearly vanishing CVPT4 contributions for bending and wagging modes. The coefficients of perturbative Dunham-type Hamiltonians in high-orders of CVPT are found to conform to the rules of equality at different orders as earlier proven analytically for diatomic molecules. The method can serve as a good substitution of the more traditional VPT2. 相似文献
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S. V. Krasnoshchekov V. V. Nechayev E. V. Isayeva N. F. Stepanov 《Moscow University Chemistry Bulletin》2010,65(1):19-29
The anharmonic model of vibrations of polyatomic molecule makes it possible, using the secondorder perturbation theory, to
interpret vibrational spectra in detail with resonances taken into account and to calculate the band intensities in spectra
for fundamental frequencies, overtones, and combination frequencies. For molecules possessing a center of symmetry (to which
trans-1,3-butadiene belongs), many vibration modes have zero intensities of absorption in IR spectra due to the mutual exclusion
rule. For meaningful analysis of vibrations of such molecules, measurement of Raman scattering (RS) spectra is necessary,
as is developing a theoretical model for calculating the anharmonic intensity. Perturbation theory (PT) in the form of contact
transformations (CTs) has proven applicable for calculating the anharmonic intensities in RS spectra. The FORTRAN software
program ANCO has been developed, which allows the calculation of vibration frequencies and IR-RS intensities of fundamental
vibrations, overtones, and combination frequencies on the basis of second-order PT in form of CTs using the polynomial representation
of potential energy, dipole moment and polarizability surfaces. The obtained frequencies and modes of anharmonic vibrations
are provided, as well as interpretation of the experimental spectrum of the trans-1,3-butadiene molecule. A procedure for calculating the scale factors of the anharmonic force field is proposed. We also
show that within the anharmonic vibration model, these factors are close to unity. 相似文献
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A mixed problem with acoustic transmission conditions for nonlinear hyperbolic equations with nonlinear dissipation is considered. The existence, uniqueness, and exponential decay of global solutions to this problem with focusing nonlinear sources are proved Additionally, the existence of global solutions and the solution blow-up in a finite time are proved for the case of defocusing nonlinear sources. 相似文献
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Computational Mathematics and Mathematical Physics - The mixed problem for nonlinear strongly dissipative wave equations with acoustic transmission conditions is considered. An existence and... 相似文献
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Abasov S. I. Agayeva S. B. Mamedova M. T. Iskenderova A. A. Imanova A. A. Zarbaliyev R. R. Isayeva E. S. Tagiyev D. B. 《Russian Journal of Applied Chemistry》2019,92(2):228-234
Russian Journal of Applied Chemistry - The conversion of straight-run naphtha on composite catalytic systems containing HZSM-5 zeolite modified with 0.4 wt % Co or Ni and 15% SZ (10% SO 4 2-... 相似文献
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