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111.
J. C. Phillips A. Peterlin Paul F. Waters 《Journal of Polymer Science.Polymer Physics》1981,19(5):789-802
A new apparatus has been developed for optical measurement of sorption/desorption in transparent polymer films at a given strain or stress. The technique utilizes a chosen infrared absorption frequency of the diffusing vapor in a spectral region where the film has negligible absorption. From the time dependence of the IR absorption at this frequency the sorption/desorption behavior of the film may be determined at any strain or stress. The simultaneous measurement of mechanical relaxation as a function of the amount of sorbed vapor is also possible. The results presented here show the applicability of the apparatus for determining the transport and mechanical properties of a low-density polyethylene film in ethyl acetate vapor at 30°C. 相似文献
112.
113.
Angeles AR Waters SP Danishefsky SJ 《Journal of the American Chemical Society》2008,130(41):13765-13770
A convergent, stereocontrolled route to either antipode of the cell adhesion inhibitor, peribysin E, has been achieved from carvone. Highlights of the synthesis include a Diels-Alder reaction to generate a cis-decalin framework, followed by semipinacol-type ring contraction to secure the stereochemistry of the C7 quaternary center. Potential mechanistic pathways for the critical ring contraction were studied through deuterium incorporation studies. In addition, an optimized olefin isomerization/Saegusa oxidation protocol is described for the conversion of [4+2] cycloadducts of 2-(trialkylsilyloxy)-1,3-dienes to 1,6(2H,7H)-naphthalenediones, having stereochemical arrangements not accessible via conventional Robinson annulation protocols. Finally, the ability to independently prepare either enantiomer of peribysin E from the corresponding antipode of carvone led to a reassignment of the absolute configuration of peribysin E. 相似文献
114.
Laughrey ZR Kiehna SE Riemen AJ Waters ML 《Journal of the American Chemical Society》2008,130(44):14625-14633
Protein-carbohydrate interactions play an important role in many biologically important processes. The recognition is mediated by a number of noncovalent interactions, including an interaction between the alpha-face of the carbohydrate and the aromatic side chain of the protein. To elucidate this interaction, it has been studied in the context of a beta-hairpin in aqueous solution, in which the interaction can be investigated in the absence of other cooperative noncovalent interactions. In this beta-hairpin system, both the aromatic side chain and the carbohydrate were varied in an effort to gain greater insight into the driving force and magnitude of the carbohydrate-pi interaction. The magnitude of the interaction was found to vary from -0.5 to -0.8 kcal/mol, depending on the nature of the aromatic ring and the carbohydrate. Replacement of the aromatic ring with an aliphatic group resulted in a decrease in interaction energy to -0.1 kcal/mol, providing evidence for the contribution of CH-pi interactions to the driving force. These findings demonstrate the significance of carbohydrate-pi interactions within biological systems and also their utility as a molecular recognition element in designed systems. 相似文献
115.
Aziz Takhirov Monika Neda Jiajia Waters 《Numerical Methods for Partial Differential Equations》2016,32(3):757-777
Modeling for fast calculation of fluid flow ensembles based on time relaxation regularization is studied herein. At each time step, the proposed model requires the storage of a single coefficient matrix with multiple right‐hands sides, corresponding to each ensemble member. The time relaxation regularization penalizes the deviation of the fluctuations from the ensemble average. The algorithm is shown to be stable under a time step restriction, which holds provided fluctuations are small enough. Also, the numerical tests show that a grad‐div stabilization weakened the condition considerably. Finite element convergence results for the time relaxation ensemble algorithm are studied too. Then, 2D and 3D numerical experiments that support the theoretical results are presented. © 2015 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 32: 757–777, 2016 相似文献
116.
The first CO2- and water-soluble peptide is reported, in which folding facilitates its solubility in CO2. 相似文献
117.
The utility of Brønsted-acidic imidazolium ionic liquid [BMIM(SO3H)][OTf] as catalyst for the high yield synthesis of a wide variety of amides under mild conditions via the Ritter reaction of alcohols with nitriles has been demonstrated. As alternative methods for the carbocation generation step, NOPF6 immobilized in [BMIM][PF6] ionic liquid was used in the Ritter reaction of bromides with nitriles and for the synthesis of adamantyl amides from adamantane and nitriles. 相似文献
118.
119.
J. Steven Morris Vickie L. Spate Ruth Ann Ngwenyama David J. Waters 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):439-444
Toenails and fingernails are routinely used to estimate selenium status in epidemiological studies; however, literature validating
nail selenium concentration as a surrogate for critical organs is limited. In this study diets of intact male dogs were selenium
supplemented at two physiological levels (3 and 6 μg/kg/day) in two different forms, selenomethionine and selenium-enriched
bioformed yeast. The selenium-adequate basal diet consumed by the treatment and control groups during the 4-week run-in period
and throughout the trial contained 0.3 ppm selenium. After 7 months the dogs in the two treatment groups and the control group
were euthanized. Representative tissue samples from prostate, brain, liver, heart and skeletal muscle were collected, rinsed
and frozen. Toenail clippings from multiple toes were also collected. Selenium was determined by neutron activation analysis
using Se77m (half life = 17.4 s) at the University of Missouri Research Reactor Center. NIST SRM 1577, Bovine Liver was analyzed
as a quality control. The analysts were blinded to control and treatment group assignments. As expected, tissue selenium levels
increased proportionally with supplementation. A slightly greater increase in tissue selenium was observed for the purified
selenomethionine compared to the bioformed yeast; however this trend was significant only for brain tissue. Toenail selenium
concentrations and tissue selenium were highly correlated (p < 0.003) with Pearson coefficients of 0.759 (skeletal muscle), 0.745 (heart), 0.729 (brain), 0.723 (prostate), and 0.632
(liver). The toenail biologic monitor accurately assesses selenium status in skeletal muscle, heart, brain, prostate, and
liver in the canine model. 相似文献
120.
Waters M Moro F Krivokapic I McMaster J van Slageren J 《Dalton transactions (Cambridge, England : 2003)》2012,41(4):1128-1130
Bis(octacyanophthalocyanine)dysprosium(III) (1) has been synthesised, characterised and magnetically studied. By the incorporation of cyano substituents on the phthalocyanine (Pc) rings, a starting point has been created for the chemical modification of double deckers for the purpose of surface self-assembly. The modification of the rings leaves the magnetic properties of the double decker largely unaffected. 相似文献