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991.
992.
Christopher M. Lee Ashutosh Mittal Anna L. Barnette Kabindra Kafle Yong Bum Park Heenae Shin David K. Johnson Sunkyu Park Seong H. Kim 《Cellulose (London, England)》2013,20(3):991-1000
Sum-frequency-generation (SFG) vibration spectroscopy is a technique only sensitive to functional groups arranged without centrosymmetry. For crystalline cellulose, SFG can detect the C6H2 and intra-chain hydrogen-bonded OH groups in the crystal. The geometries of these groups are sensitive to the hydrogen bonding network that stabilizes each cellulose polymorph. Therefore, SFG can distinguish cellulose polymorphs (Iβ, II, IIII and IIIII) which have different conformations of the exocyclic hydroxymethylene group or directionalities of glucan chains. The C6H2 asymmetric stretching peaks at 2,944 cm?1 for cellulose Iβ and 2,960 cm?1 for cellulose II, IIII and IIIII corresponds to the trans-gauche (tg) and gauche-trans (gt) conformation, respectively. The SFG intensity of the stretch peak of intra-chain hydrogen-bonded O–H group implies that the chain arrangement in cellulose crystal is parallel in Iβ and IIII, and antiparallel in II and IIIII. 相似文献
993.
Richard W. Hutchinson Kavita George Doug Johns Lee Craven Gary Zhang Pullen Shnoda 《Cellulose (London, England)》2013,20(1):537-545
Oxidized regenerated cellulose (ORC) has been used as an absorbable hemostat since World War II. In the present study, hemostasis time was determined in a spleen incision model in swine. The effect of mass on absorbable hemostat efficacy and hemostasis time was evaluated by standardizing the ORC materials on a mass basis. The median hemostasis time for a single layer of the new nonwoven ORC was as much as 51 % shorter than woven ORC (P < 0.001). The mean hemostasis time for nonwoven ORC was not affected by the mass of hemostat applied to the wound. The hemostatic efficacy of woven ORC increased with the mass (layers) of hemostat applied to the wound. Nonwoven ORC is significantly faster in achieving hemostasis than woven ORC, and its hemostatic efficacy is not influenced by the mass of material applied. Tissue reaction was minimal and the material was fully absorbed by 14 days. 相似文献
994.
Hyeonbae Kang Hyundae Lee Mikyoung Lim 《Mathematical Methods in the Applied Sciences》2015,38(9):1847-1854
We present a new systematic method to compute the Riemann mapping from the outside of the unit disc to the outside of a simply connected domain. We derive explicit relations between the coefficients of the Riemann mapping and the generalized polarization tensors associated with the domain. Because the generalized polarization tensors can be computed numerically, we are able to compute the coefficients of the Riemann mapping using these relations. Effectiveness of the method is validated by numerical examples. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
995.
996.
This article addresses the dynamic output feedback consensus problem of continuous‐time networked multiagent systems. Both a fixed topology and Markovian switching topologies are considered. The consensus algorithms are on the base of the output information of each agent's itself and its neighbors. Some sufficient conditions for consensus of multiagent systems are obtained in forms of bilinear matrix inequalities. The algorithm based on the homotopy continuation method is given to compute the feasible controller gains. Numerical simulations are given to show the effectiveness of the proposed results. © 2014 Wiley Periodicals, Inc. Complexity 20: 35–42, 2015 相似文献
997.
We synthesized a fluorescent adenosine derivative, rApy, as a probe to study RNA structural transitions, in particular the intermolecular G-quadruplex formation. rApy was incorporated into the dangling positions of guanine-rich oligonucleotides, which under physiological conditions undergo π-stacking on top of each other exhibiting a strong emission signal in their G-quadruplex conformation, but not in their single-stranded state. 相似文献
998.
New methallylsilanated phosphorylcholine (MASPCs) were synthesized via a copper-catalyzed ‘click’ reaction and demonstrated excellent moisture stability. Hydroxylated silicon compounds, silanol, and silica were grafted or modified by MASPCs in the presence of triflic acid (TfOH) and they possessed a good grafting efficiency and high loading rate. 相似文献
999.
seco-Iso-cyclopropylfurano[e]indoline-trimethoxyindole 1 and seco-cyclopropylfurano[f]quinoline-trimethoxyindole 2 are potent cytotoxic agents. Previous synthesis of these compounds was inefficient and the approach required separation of a mixture containing the isomeric indoline and quinoline intermediates 11 and 12, formed from radical cyclization of allylic bromide 10. Reported herein is an efficient and selective synthesis of either intermediate 11 or 12, thus product 1 or 2, as needed. The conditions of the Stobbe condensation, bromination, 5-exo-trig radical cyclization, amine-carboxylic acid coupling, and debenzylation were optimized for multi gram scale. As a result, the reaction times were shortened, the products were readily isolated, and the yields and purity improved. 相似文献
1000.
Eun Joung Choi Eunha Kim Youngjun Lee Ala Jo Seung Bum Park 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(5):1370-1374
Fluorescence imaging enables the uniquely sensitive observation of functional‐ and molecular‐recognition events in living cells. However, only a limited range of biological processes have been subjected to imaging because of the lack of a design strategy and difficulties in the synthesis of biosensors. Herein, we report a facile synthesis of emission‐tunable and predictable Seoul‐Fluors, 9‐aryl‐1,2‐dihydrolopyrrolo[3,4‐b]indolizin‐3‐ones, with various R1 and R2 substituents by coinage‐metal‐catalyzed intramolecular 1,3‐dipolar cycloaddition and subsequent palladium‐mediated C H activation. We also showed that the quantum yields of Seoul‐Fluors are controlled by the electronic nature of the substituents, which influences the extent of photoinduced electron transfer. On the basis of this understanding, we demonstrated our design strategy by the development of a Seoul‐Fluor‐based chemosensor 20 for reactive oxygen species that was not accessible by a previous synthetic route. 相似文献