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131.
132.
Ewan Sprong Deon De Wet‐Roos Matthew Tonge Ron Sanderson 《Journal of Polymer Science.Polymer Physics》2004,42(13):2502-2512
Model alkali‐soluble rheology modifiers were synthesized through the reversible addition–fragmentation chain transfer polymerization of methyl methacrylate, methacrylic acid, and three different associative macromonomers containing 20, 50, and 100 ethylene oxide spacer units, respectively. The synthesized polymers showed well‐controlled molar masses and narrow molar mass distributions. The rheological properties of the model alkali‐soluble rheology modifiers were measured in alkali solutions and in the presence of a well‐characterized core–shell emulsion. The steady‐shear viscosity data for the emulsion solutions, thickened with the associative rheology modifiers, were described by the Carreau model. The rheology modifiers containing the macromonomers with the longest ethylene oxide spacer units produced the highest viscosity in the latex systems but the lowest viscosity in alkali solutions. The highest viscosities in alkali solutions were obtained for the rheology modifiers containing macromonomers with 50 ethylene oxide spacer units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2502–2512, 2004 相似文献
133.
We analyze nonlinear coupling between individual vibrational quanta for trapped ions. The nonlinear Coulomb interaction causes a Kerr-type Hamiltonian, for which we derive an analytical expression for the coupling constant χ. In contrast to a previously published formula [C.F. Roos, T. Monz, K. Kim, M. Riebe, H. Häffner, D.F.V. James, R. Blatt, Phys. Rev. A 77 (2008) 040302(R)], our result is in close agreement with experimental data. 相似文献
134.
Interior-point methods for semidefinite optimization have been studied intensively, due to their polynomial complexity and
practical efficiency. Recently, the second author designed a primal-dual infeasible interior-point algorithm with the currently
best iteration bound for linear optimization problems. Since the algorithm uses only full Newton steps, it has the advantage
that no line-searches are needed. In this paper we extend the algorithm to semidefinite optimization. The algorithm constructs
strictly feasible iterates for a sequence of perturbations of the given problem and its dual problem, close to their central
paths. Two types of full-Newton steps are used, feasibility steps and (ordinary) centering steps, respectively. The algorithm
starts from strictly feasible iterates of a perturbed pair, on its central path, and feasibility steps find strictly feasible
iterates for the next perturbed pair. By using centering steps for the new perturbed pair, we obtain strictly feasible iterates
close enough to the central path of the new perturbed pair. The starting point depends on a positive number ζ. The algorithm terminates either by finding an ε-solution or by detecting that the primal-dual problem pair has no optimal solution (X
*,y
*,S
*) with vanishing duality gap such that the eigenvalues of X
* and S
* do not exceed ζ. The iteration bound coincides with the currently best iteration bound for semidefinite optimization problems. 相似文献
135.
Dr. Varsha V. Kapoerchan Dr. Annemiek D. Knijnenburg Miquel Niamat Emile Spalburg Dr. Albert J. de Neeling Dr. Peter H. Nibbering Roos H. Mars‐Groenendijk Dr. Daan Noort José M. Otero Dr. Antonio L. Llamas‐Saiz Dr. Mark J. van Raaij Prof. Dr. Gijs A. van der Marel Prof. Dr. Herman S. Overkleeft Dr. Mark Overhand 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(40):12174-12181
The cyclic cationic antimicrobial peptide gramicidin S (GS) is an effective topical antibacterial agent that is toxic for human red blood cells (hemolysis). Herein, we present a series of amphiphilic derivatives of GS with either two or four positive charges and characteristics ranging between very polar and very hydrophobic. Screening of this series of peptide derivatives identified a compound that combines effective antibacterial activity with virtually no toxicity within the same concentration range. This peptide acts against both Gram‐negative and Gram‐positive bacteria, including several MRSA strains, and represents an interesting lead for the development of a broadly applicable antibiotic. 相似文献
136.
Methyl acrylate reacts with α,β-unsaturated aldehydes in the presence of a tertiary amine to afford 1,2-addition products. 相似文献
137.
138.
Hans-Goerg Roos 《计算数学(英文版)》2009,(2):266-279
The application of a standard Galerkin finite element method for convection-diffusion problems leads to oscillations in the discrete solution, therefore stabilization seems to be necessary. We discuss several recent stabilization methods, especially its combination with a Galerkin method on layer-adapted meshes. Supercloseness results obtained allow an improvement of the discrete solution using recovery techniques. 相似文献
139.
Multiconfigurational quantum chemical methods (CASSCF/CASPT2) have been used to study the chemical bond in the actinide diatoms Ac2, Th2, Pa2, and U2. Scalar relativistic effects and spin-orbit coupling have been included in the calculations. In the Ac2 and Th2 diatoms the atomic 6d, 7s, and 7p orbitals are the significant contributors to the bond, while for the two heavier diatoms, the 5f orbitals become increasingly important. Ac2 is characterized by a double bond with a 3Sigmag-(0g+) ground state, a bond distance of 3.64. A, and a bond energy of 1.19 eV. Th2 has quadruple bond character with a 3Dg(1g) ground state. The bond distance is 2.76 A and the bond energy (D0) 3.28 eV. Pa2 is characterized by a quintuple bond with a 3Sigmag-(0g+) ground state. The bond distance is 2.37 A and the bond energy 4.00 eV. The uranium diatom has also a quintuple bond with a 7Og (8g) ground state, a bond distance of 2.43 A, and a bond energy of 1.15 eV. It is concluded that the strongest bound actinide diatom is Pa2, characterized by a well-developed quintuple bond. 相似文献
140.
Results from quantum chemical calculations that predict the existence of a series of diuranium molecules are reported. Two diuranium chlorides, U(2)Cl(6) and U(2)Cl(8)(2)(-), and three different carboxylates, U(2)(OCHO)(4), U(2)(OCHO)(6), and U(2)(OCHO)(4)Cl(2) have been studied. All species have been found to be stable with a multiply bonded U(2) unit. 相似文献