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121.
Jason E. Imbriglio Daniel DiRocco Subharekha Raghavan Richard G. Ball Nancy Tsou Ralph T. Mosley James R. Tata Steven L. Colletti 《Tetrahedron letters》2008,49(33):4897-4900
The optimization of a palladium-catalyzed amidation reaction providing a new class of amino acid-tetrahydroanthranilic acid derivatives has been achieved. The scope of the reaction and preliminary conformational analysis of the resulting series of molecules is discussed. 相似文献
122.
J. Greener A. H. Tsou K. C. Ng W. A. Chen 《Journal of Polymer Science.Polymer Physics》1991,29(7):843-858
When a flat film is bent to some fixed curvature, held at this state for some time, and then released, its curvature is usually observed to drop instantaneously to some finite value and then gradually decrease with time. This phenomenon, generally referred to as bending recovery, has been modeled by simple extension of the classical plate-bending theory to linear-viscoelastic materials. The model assumes that the relaxation spectra in tension and compression are dissimilar but are interrelated through a simple temporal shift. Experimental data, including instantaneous recovery at ambient and elevated temperatures as well as recovery over extended times, have been generated for four films with widely different relaxation characteristics. The data are in reasonable agreement with predictions of the model if a constant value of the compressive shift parameter (see text) is used for all materials. The model indicates that the bending recovery of a polymer film is intimately related to its relaxation spectrum and can be effectively manipulated by changes in temperature and winding time. 相似文献
123.
Dorothy J. Rabiger Mildred Y. Chang S. Matsukawa K. C. Tsou 《Journal of heterocyclic chemistry》1970,7(2):307-311
The synthesis of 5-iodo-3-indolyl and 5-nitro-3-indolyl phosphate for cytochemical demonstration of acid phosphatase is reported. Enzymatic hydrolysis of these compounds liberates the corresponding indoxyl which is oxidized to the substituted indigo at an acid pH. In contrast, the 5-bromo and the unsubstituted indoxyl are not oxidized readily at an acid pH. Comparison of the UV and visible, spectra of the disubstituted indigo has offered a partial explanation for this difference. E.S.R. measurements showed that 5,5′-diiodoindigo, unlike 5,5′-dibromoindigo, gives a detectable radical ion at an acid pH. 相似文献
124.
M. Takai S. C. Tsou P. H. Tsien D. Röschenthaler H. Ryssel 《Applied Physics A: Materials Science & Processing》1981,24(4):319-322
A Q-switched Nd: YAG laser with a pulse duration of 20 ns was used to investigate effects of laser annealing in gallium implanted
silicon. Rutherford backscattering and Hall-effect measurements were performed to evaluate the annealed layer. Differential
Hall-effect measurements were carried out to obtain carrier concentration profiles after annealing. It was found that a maximum
sheet carrier concentration of 8×1015 cm−2 can be obtained for a gallium implantation of 1016 cm−2 by laser annealing with an energy density of more than 1.0 J cm−2. Although the peak carrier concentration was found to be 8.0×1020 cm−3, the annealed layer showed polycrystalline structures even after annealing with an energy density up to 4J cm−2. The annealing took place in the solid phase in this energy density range. 相似文献
125.
Staas DD Savage KL Homnick CF Tsou NN Ball RG 《The Journal of organic chemistry》2002,67(23):8276-8279
Addition of the Reformatsky reagent derived from ethyl bromodifluoroacetate to alkyl- and aryl-substituted N-tert-butylsulfinimines furnishes beta-tert-butylsulfinamyl-beta-substituted alpha,alpha-difluoroproponiates in diastereomeric ratios ranging from 80:20 to 95:5. The diastereomers are easily separated and the enantiomerically pure, protected beta-amino esters are readily transformed to the corresponding acid, amide, and amine derivatives as useful synthons for medicinal chemistry targets. 相似文献
126.
Tsung-Shan Tsou 《Computational Statistics》2011,26(3):507-519
This article is concerned with inference about link function in generalized linear models. A parametric and yet robust likelihood
approach is introduced to accomplish the intended goal. More specifically, it is demonstrated that one can convert normal
and gamma likelihoods into robust likelihood functions for the link function. The asymptotic validity of the robust likelihood
requires only the existence of the second moments of the underlying distributions. The application of this novel robust likelihood
method is demonstrated on the Box–Cox transformation. Simulation studies and real data analysis are provided to demonstrate
the efficacy of the new parametric robust procedures. 相似文献
127.
Rigid–rigid blends made of ionomer and ionomer precursor polymer, based on poly(methyl methacrylate) (PMMA), have been investigated. Two series of blends have been prepared for studying mechanical properties. In one series, dynamic mechanical properties were determined over a wide range of temperatures. As the weight fraction of the ionomer was increased, there was a modest increase of modulus at ambient temperature and a very large increase in the rubbery modulus at elevated temperatures above the glass transition temperature of PMMA. In a second series of tests, tensile stress–strain measurements, made at an ambient temperature, were carried out over a wide range of blend compositions. For all blends tested, the mechanical properties exhibited a synergistic enhancement, i.e., average values of modulus, strength and fracture energy were all higher than expected based on the rule of mixtures. Measurements of fracture toughness also exhibited synergy, with a maximum value, higher than the value of either blend component, being attained in blends containing about 30 wt % of the PMMA ionomer. These results are interpreted in terms of a higher resistance to fracture of the more chain-entangled ionomer phase and good interfacial adhesion between the two components of the blend. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1235–1245, 1998 相似文献
128.
Hsuan‐Ying Chen Hsin‐Jou Fang Yen‐Jen Chen Sodio C. N. Hsu Yi‐Chun Lai Hsiu‐Wei Ou Wei‐Te Peng Ya‐Ju Chang Yu‐Chi Tsou Ting‐Yi Wu Hsuan Chung Yun Chen Ta Chou Huang Bo Sheng Wu 《Journal of polymer science. Part A, Polymer chemistry》2012,50(16):3286-3294
Ring‐opening polymerization (ROP) of ε‐caprolactone and L‐lactide (LA) was studied using stannous(II) 2‐ethylhexanoate (Sn(Oct)2) with N,N‐dimethylformamide‐dimethyl acetal (DMF‐DMA). DMF‐DMA showed a tenfold improvement in catalytic activity over that of Sn(Oct)2 under the same conditions. It also enhanced the capability to control molecular weight in the synthesis of small molecular weight polymers of polycaprolactone and polylactide (PLA). The high molecular weight polymerization demonstrated a strong capability to control molecular weight for the polymerization of LA: a molecular weight of PLA exceeding 400,000 was obtained at very low catalytic loadings. The individual polymerization rates of other tin reagents with DMF‐DMA also clearly increased. Applying this methodology could drastically reduce the time and cost required for the fabrication of these products to increase the competitive advantage of manufacturers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
129.
Collapsed (kippah) hollow silica nanoparticles 总被引:1,自引:0,他引:1
Novel collapsed kippah-like mesoporous silica nanoparticles were synthesized using an O/W microemulsion system. The oil (hexadecane) can escape from the core while water could not enter through the surfactant filled nanopores of the soft shell during synthesis. 相似文献
130.
Shih-Yung Tsou Hsuan-Sheng Lin Po-Jen Cheng Chien-Lin Huang Jeng-Yue Wu Chi Wang 《European Polymer Journal》2013
Polyamide 6 (PA6) solutions in formic acid (FA) and deionized water cosolvent may behave as polyelectrolyte or neutral solutions depending on the cosolvent composition. In this study, both polyelectrolyte and neutral PA6 solutions were prepared for electrospinning, and their spinnability was correlated with their rheological properties. In addition, the effects of PA6 average molecular weight and carbon nanocapsule (CNC) nanoparticle addition on solution rheology and electrospinnability were investigated. Microstructure and thermal properties of the as-spun fibers were identified by wide-angle X-ray diffraction, polarized Fourier infrared spectroscopy, and differential scanning calorimetry (DSC). Due to the chain expansion, polyelectrolyte solutions with 99 vol.% FA solvent possess much lower entanglement concentration (?e, ∼1 wt.%) than neutral solutions (∼7 wt.%) prepared by 90 and 85 vol.% FA solvent. Compared with the neutral solution, the polyelectrolyte solution is more advantageous because a lower concentration is sufficient to obtain bead-free PA6 fibers. However, at a concentrated regime of 15 wt.% solution, the obtained fibers exhibit a larger diameter due to the higher entanglement density. For the crystalline structure, the content and orientation of α-form crystals are higher in the PA6 fibers obtained from the polyelectrolyte than from the neutral solution. When PA6 with a lower molecular weight is used, a higher concentration is required to develop the entangled chains to produce bead-free fibers. Homogeneous PA6 solutions filled with CNCs exhibit more elastic behavior than unfilled solutions due to the presence of the CNC–CNC network, aside from the entangled network of PA6 chains. Electrospinning of the CNC-filled solutions yields PA6 fibers with CNC aggregates protruding from the fiber surface. The inclusion of CNC in the PA6/FA solution produces fibers possessing enhanced α-form crystals with reduced orientation. In all cases, DSC heating traces of the as-spun fibers identify a high melting temperature (HMT) phase of PA6. The amount of HMT phase decreases, provided that more water or CNCs are added into the PA6/FA solution for electrospinning. 相似文献