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61.
Anastassia N. Rissanou Spiros H. Anastasiadis Ioannis A. Bitsanis 《Journal of polymer science. Part A, Polymer chemistry》2009,47(24):2462-2476
When a polymer chain in solution interacts with an atomically smooth solid substrate, its conformational properties are strongly modified and deviate substantially from those of chains in bulk. In this work, the interplay of two competing transitions that affect the conformations of polymer chains near an energetically attractive surface is studied by means of Monte Carlo simulations on a cubic lattice. The transition from an extended to a compact conformation of a polymer chain near an attractive wall, as solubility deteriorates, exhibits characteristics akin to the “coil-to-globule” transition in bulk. An effective θ-temperature is determined. Its role as the transition point is confirmed in a variety of ways. The nature of the coil-to-compact transition is not qualitatively different from that in the bulk. Adsorbed polymer chains may assume “globular” or “pancake” configurations depending on the competition among adsorption strength, cohesive energy, and entropy. In a very relevant range of conditions, the dependence of the adsorbate thickness on chain-length is intermediate between that of 3-d (“semidroplets”) and 2-d (“pancake”) objects. The focus of this study is on rather long polymer chains. Several crucial features of the transitions of the adsorbed chains are N-dependent and various aspects of the adsorption and “dissolution” process are manifested clearly only at the “long chain” limit. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2462–2476, 2009 相似文献
62.
A tris(bromo-methylphenylene)triazine and its corresponding phosphine oxide derivative have been synthesized; the latter compound was found to be a potent ligand for the hydroformylation reaction. Suzuki coupling of the mono-pinacolboronate derivative of the former compound with a tris(iodo-methylphenylene)triazine was possible at two of the three iodine atoms, yielding a bromo- and iodo-methylphenylene periphery-functionalized triazine-based dendritic molecule with a 3,3′-dimethyl-biphenyl linker. 相似文献
63.
Ioannis K. Argyros 《Applied mathematics and computation》2009,215(4):1553-1560
We provide sufficient conditions for the semilocal convergence of Newton’s method to a locally unique solution of a nonlinear operator equation containing operators that are Fréchet-differentiable of order at least two, in a Banach space setting. Numerical examples are also provided to show that our results apply to solve nonlinear equations in cases earlier ones cannot [J.M. Gutiérrez, A new semilocal convergence theorem for Newton’s method, J. Comput. Appl. Math. 79(1997) 131-145; Z. Huang, A note of Kantorovich theorem for Newton iteration, J. Comput. Appl. Math. 47 (1993) 211-217; F.A. Potra, Sharp error bounds for a class of Newton-like methods, Libertas Mathematica 5 (1985) 71-84]. 相似文献
64.
Anno Hein Ioannis Karatasios Dionysis Mourelatos 《Analytical and bioanalytical chemistry》2009,395(7):2061-2071
The present case study concerns the technology of Byzantine wall paintings from the Mani Peninsula, Greece. An assemblage
of 12 Byzantine churches, constructed in the tenth to fifteenth century, was included in an initial analytical survey. Two
random samples of wall paintings were taken in each monument in order to study their micro stratigraphy and the composition
of pigment and plaster layers. Polished sections were fabricated for examination with optical microscopy and scanning electron
microscopy (SEM). Furthermore, selected samples were powdered and analysed with Fourier-transformed infrared spectroscopy
(FTIR) and X-ray diffraction (XRD). The analytical results achieved in this case study provided general conclusions concerning
painting techniques for wall paintings in a rather provincial area of the Byzantine Empire. The palette comprised mainly earthen
pigments like ochres and carbon black but occasionally also other pigments like cinnabar, minium and ultramarine. In view
of future studies, a portable X-ray fluorescence analysis (XRF) set-up was tested. 相似文献
65.
The Kantorovich theorem is a fundamental tool in nonlinear analysis for proving the existence and uniqueness of solutions
of nonlinear equations arising in various fields. In the present paper we formulate and prove a generalized Kantorovich theorem
that contains as special cases the Kantorovich theorem and a weak Kantorovich theorem recently proved by Uko and Argyros.
An illustrative example is given to show that the new theorem is applicable in some situations in which the other two theorems
are not applicable. 相似文献
66.
Emmanouil H. Papaioannou Maria Liakopoulou-Kyriakides Dimitrios Christofilos Ioannis Arvanitidis Gerasimos Kourouklis 《Applied biochemistry and biotechnology》2009,159(2):478-487
In the present study, we explore the feasibility of Raman spectroscopy for intracellular monitoring of carotenoid in filamentous
fungi Blakeslea trispora. Although carotenoid production from this fungus has been extensively studied through various chromatographic methods and
ultraviolet-visible spectroscopy, no intracellular monitoring has been demonstrated until now. The intensity of the Raman
spectrum, and more conveniently that of the strongest ν
1 carotenoid band at ∼1,519 cm−1, exhibits a good linear correlation with the carotenoid content of the sample as determined by high-performance liquid chromatography
(HPLC) and ultraviolet-visible (UV-Vis) spectroscopy. Our results suggest that Raman spectroscopy can serve as an alternative
method for the study and quantification of carotenoid in batch-mated submerged cultivations of B. trispora and similar organisms. Although not as accurate as HPLC, it allows a rapid sampling and analysis, avoiding the prolonged
and tedious classical isolation procedures required for carotenoid determination by HPLC and UV-Vis spectroscopy. 相似文献
67.
The vapor–liquid equilibria of binary polymer–solvent systems was modeled using the Non-Random Hydrogen Bonding (NRHB) model. Mixtures of poly(ethylene glycol), poly(propylene glycol), poly(vinyl alcohol) and poly(vinyl acetate) with various solvents were investigated, while emphasis was put on hydrogen bonding systems, in which functional groups of the polymer chain can self-associate or cross-associate with the solvent molecules. Effort has been made to explicitly account for all hydrogen bonding interactions. The results reveal that the NRHB model offers a flexible approach to account for various self- or cross-associating interactions. In most cases model's predictions (using no binary interaction parameter kij = 0) and model's correlations (using one temperature independent binary interaction parameter, kij ≠ 0) are in satisfactory agreement with the experimental data, despite the complexity of the examined systems. 相似文献
68.
Nikolaos Gialelis Ioannis G. Stratis 《Mathematical Methods in the Applied Sciences》2019,42(15):4939-4956
We show local existence of certain type of solutions for the Cauchy problem of the defocusing nonlinear Schrödinger equation with pure power nonlinearity, in various cases of open sets, unbounded or bounded. These solutions do not vanish at the boundary or at infinity. We also show, in certain cases, that these solutions are unique and global. 相似文献
69.
Stefania Corsaro Ioannis Kyriakou Daniele Marazzina Zelda Marino 《European Journal of Operational Research》2019,272(3):1082-1095
In this paper, we present a transform-based algorithm for pricing discretely monitored arithmetic Asian options with remarkable accuracy in a general stochastic volatility framework, including affine models and time-changed Lévy processes. The accuracy is justified both theoretically and experimentally. In addition, to speed up the valuation process, we employ high-performance computing technologies. More specifically, we develop a parallel option pricing system that can be easily reproduced on parallel computers, also realized as a cluster of personal computers. Numerical results showing the accuracy, speed and efficiency of the procedure are reported in the paper. 相似文献
70.
Christos Raptis Ioannis N. Lykakis Dr. Constantinos Tsangarakis Dr. Manolis Stratakis Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):11918-11927
Based on stereoisotopic studies and β‐secondary isotope effects, we propose that the acid‐catalyzed cyclization of geranyl acetate proceeds through a concerted mechanism. Under heterogeneous conditions (zeolite Y confinement), a preorganized chairlike transition state predominates, whereas under homogeneous conditions the boat‐ and chairlike transition states are almost isoenergetic. For the case of farnesyl acetate, we propose that under homogeneous conditions a concerted dicyclization occurs with a preorganized boat–chair transition state competing with the chair–chair transition state. Under zeolite confinement conditions, the chair–chairlike dicyclization transition state is highly favorable. The preference of chairlike transition states within the cavities of zeolite Y is attributed to a transition state shape selectivity effect. 相似文献