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1.
Shigeyuki Toki Igors Sics Benjamin S. Hsiao Syozo Murakami Masatoshi Tosaka Sirilux Poompradub Shinzo Kohjiya Yuko Ikeda 《Journal of Polymer Science.Polymer Physics》2004,42(6):956-964
The molecular orientation and strain‐induced crystallization of synthetic rubbers—polyisoprene rubber, polybutadiene rubber, and butyl rubber [poly(isobutylene isoprene)]—during uniaxial deformation were studied with in situ synchrotron wide‐angle X‐ray diffraction. The high intensity of the synchrotron X‐rays and the new data analysis method made it possible to estimate the mass fractions of the strain‐induced crystals and amorphous chain segments in both the oriented and unoriented states. Contrary to the conventional concept, the majority of the molecules (50–75%) remained in an unoriented amorphous state at high strains. Each synthetic rubber showed a different behavior of strain‐induced crystallization and molecular orientation during extension and retraction. Our results confirmed the occurence of strain‐induced networks in the synthetic rubbers due to the inhomogeneity of the crosslink distribution. The strain‐induced networks containing microfibrillar crystals and oriented amorphous tie chains were responsible for the ultimate mechanical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 956–964, 2004 相似文献
2.
Following a previous systematic theoretical study of the ground-state properties of over 7000 nuclei from the proton drip line to the neutron drip line in the relativistic mean field model [Prog. Theor. Phys. 113 (2005) 785], which is in fair agreement with existing experimental data, we observe a few spurious shell closures, i.e. proton shell closures at Z = 58 and Z = 92. These spurious shell closures are found to persist in all the effective forces of the relativistic mean field model, e.g. TMA, NL3, PKDD and DD-ME2. 相似文献
3.
4.
Adler J Becker JJ Blaylock GT Bolton T Brient J Browder T Brown JS Bunnell KO Burchell M Burnett TH Cassell RE Coffman D Cook V Coward DH DeJongh F Dorfan DE Drinkard J Dubois GP Eigen G Einsweiler KF Eisenstein BI Freese T Gatto C Gladding G Grab C Hamilton RP Hauser J Heusch CA Hitlin DG Izen JM Kim PC Köpke L Li A Lockman WS Mallik U Matthews CG Mincer AI Mir R Mockett PM Mozley RF Nemati B Odian A Parrish L Partridge R Pitman D Plaetzer SA Richman JD Sadrozinski HF Scarlatella M Schalk TL 《Physical review letters》1989,62(16):1821-1824
5.
Blaylock GT Bolton T Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Dorfan DE Dubois GP Eigen G Eisenstein BI Freese T Gladding G Grab C Heusch CA Hitlin DG Izen JM Köpke L Li A Lockman WS Mallik U Matthews CG Mir R Mockett PM Mozley RF Nemati B Odian A Parker J Parrish L Partridge R Pitman D Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Simopoulos C Stockdale IE Stockhausen W Thaler JJ Toki W Tripsas B Villa F Wasserbaech S Wattenberg A Weinstein AJ 《Physical review letters》1987,58(21):2171-2174
6.
Arakawa Y Ohnishi M Yoshimura N Yoshifuji S 《Chemical & pharmaceutical bulletin》2003,51(8):1015-1020
Synthesis of (1R,2S,5S,6R,8S)-3-azabicyclo[3.3.0]octane-2,6,8-tricarboxylic acid (2) from trans-4-hydroxy-L-proline (5) was attempted. A Diels-Alder reaction of 3,4-dehydroproline derivative 9 and cyclopentadiene afforded a single stereoisomer 11. The Diels-Alder adduct was smoothly converted to the hydrochloride of 2 (24) via RuO(4) oxidation. Although some racemization of the material or product was observed during the synthetic processes, the amino acid 24 proved to be optically pure. 相似文献
7.
Baltrusaitis RM Becker JJ Blaylock GT Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Cui H Del Papa C Dorfan DE Duncan AL Einsweiler KF Eisenstein BI Fabrizio R Gladding G Grancagnolo F Hamilton RP Hauser J Heusch CA Hitlin DG Köpke L Mockett PM Moss L Mozley RF Nappi A Odian A Partridge R Perrier J Plaetzer SA Richman JD Roehrig JR Russell JJ Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Sleeman JC Spadafora AL Thaler JJ Toki W Unno Y Villa F Wattenberg A 《Physical review letters》1985,55(17):1723-1726
8.
Yoshio Okamoto Motoyuki Toki Heimei Yuki 《Journal of polymer science. Part A, Polymer chemistry》1979,17(11):3705-3712
S-Methyl thiomethacrylate (methyl thiolmethacrylate, MTMA) was polymerized with a variety of anionic initiators such as n-BuLi, octylpotassium, PhMgBr, and Et2AlNPh2 in toluene and THF. Stereoregularity of the polymer (PMTMA) was determined from the 1H-NMR spectrum of poly(methyl methacrylate), which had been derived from PMTMA, because the α-methyl resonance in the 1H-NMR spectrum of PMTMA was not satisfactorily solved owing to the overlap of pentad signals. The 13C-NMR spectrum of PMTMA also showed the splitting due to pentad sequences. Stereoregularity of PMTMA was always low compared with that of poly(methyl methacrylate), which was prepared under the same reaction conditions. MTMA was much more reactive than methyl methacrylate and methacrylonitrile in the copolymerization with n-BuLi in toluene and in THF at ?78°C. The lower stereoregulation of the polymerization of MTMA and the higher reactivity of MTMA were mainly ascribed to the higher resonance effect of MTMA. 相似文献
9.
Motoyuki Toki 《Journal of Sol-Gel Science and Technology》1994,2(1-3):97-101
This paper describes the attempt to prepare a new group of monodispersed silica-polymer hybrid particles, which consists of silica and amide polymer: poly(vinylpyrrolidone) (PVP) and poly(2-ethyloxazoline) (POXZ). Preparation method is based on the growth of hybrid seeds by the addition of TEOS-polymer solution.Monodispersed PVP-silica hybrid particles of 1.24 µm in diameter were prepared by growing the hybrid seeds of 0.54 µm by the addition of TEOS-PVP solution with ammonia catalyst. In the case of POXZ-silica particles, addition of TEOS-POXZ solution to the solution containing 0.54 µm seeds resulted in monodispersed POXZ-silica hybrid particles and four times repetition of the addition for particle growth gave the hybrid particles of the diameter of 1.6 µm.Improvement of mechanical properties of hybrid particles was observed when the particles were heated at 100 200°C. 相似文献
10.
The elution behaviors of the biogenic amines, histamine (HA) and its metabolite methyl histamine (MHA), were evaluated by means of on-column derivatization (OCD)-capillary electrochromatography (CEC) which employed a monolithic octadecylsilica (ODS) capillary column (20 cm of effective length x 50 microm of inner diameter). Five kinds of alkylthiols, e.g., 2- hydroxyethylthiol (or 2-mercaptoethanol (2-ME)), ethanethiol (ET), 1-propanethiol (1-PT), 2-methyl-1-propanethiol (2-MPT) and 1-butanethiol (1-BT) were separately presented at 5 mM each in the OCD-CEC separation run buffer consisting of 60% acetonitrile in 5 mM o-phthalaldehyde (OPA)-10 mM borate buffer (pH 10). When 2-ME was present in the run buffer solution, both derivatives corresponding to HA and MHA migrated separately, but closely together through the capillary column. Replacement of 2-ME with 1-BT in the run buffer solution caused a delay in their elution profiles on the electrochromatogram and the separation between those two peaks became remarkably improved. The elution times of HA and MHA followed the increase in alkyl chain length or hydrophobicity of thiol, 1-BT > 2-MPT > 1-PT > ET > 2-ME. Performance of on-line preconcentrations of HA and MHA was also evaluated by varying the electrokinetic injection voltage from 1 kV to 8 kV. The peak area counts corresponding to HA recorded about 50 times higher when 2 kV was applied for 240 s to a 0.1 mM HA solution than when 8 kV was applied for 5 s. This method was next applied to a sample of human urine spiked with HA and MHA at levels of 0.1 microM each. Although HA and MHA peaks were not identifiable among the peaks corresponding to the materials in the urine matrix when OPA/2-ME was employed in a run buffer for the OCD-CEC, the separation and identification of their peaks became possible by replacing 2-ME with 1-BT in the run buffer solution. 相似文献