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181.
182.
Katsuhito Suzuki Yoko Homma Yuko Igarashi Hiroaki Okumura Hiroyuki Yano 《Cellulose (London, England)》2017,24(9):3789-3801
Microfibrillated cellulose (MFC)-reinforced polypropylene (PP) was prepared via two engineering approaches: disintegration of the pulp by a bead mill followed by a melt-compounding process with PP (B-MFC-reinforced PP); and disintegration of the pulp mixed with PP by a twin screw extruder followed by a melt-compounding process (T-MFC-reinforced PP). The effects that the engineering process and the microfibrillation of the pulp had upon the dispersion and mechanical properties were investigated through tensile tests, rheological analysis and X-ray computed tomography. The bead-milling method enabled a uniform microfibrillation of the pulp to under 100 nm, which corresponded to a surface area of 133–146 m2/g for the pulp, found by the Brunauer–Emmett–Teller (BET) analysis. The T-MFC-reinforced PP with 30 wt% MFC content exhibited a tensile modulus of 5.3 GPa and a strength of 85 MPa, whereas the B-MFC-reinforced PP composites with the same content of MFC exhibited values of 4.1 GPa and 59.6 MPa, respectively. Rheological analysis revealed that the complex viscosity and storage modulus at 170 °C of T-MFC-reinforced PP with 30 wt% MFC content are 5–7 and 5–8 times higher than that of B-MFC-reinforced PP, respectively. This indicated that T-MFC was more dispersed in the PP than B-MFC. Therefore, T-MFC produced a more rigid interconnected network in the matrix during the melting state than B-MFC. 相似文献
183.
In order to develop criteria for the physical evaluation of wood for soundboards of musical instruments, measurements were made of dynamic Young's modulusE, static Young's modulusE, internal frictionQ
–1 in longitudinal direction, and specific gravity for numerous species of broad-leaved wood. From the results obtained, including those of our previous paper on coniferous wood [1], it was found that the suitability of wood for soundboards could be evaluated by the quantity ofQ
–1/(E/), and that there were very high correlations betweenQ
–1/(E/) andE/, and betweenE andE, regardless of wood species. Consequently, it becomes possible to select practically any wood suitable for soundboards by using the value ofE/, which can be measured easily, and it was derived that the relation betweenE/ andQ
–1 of wood could be expressed by an exponential equation regardless of wood species. 相似文献
184.
Iwao Okamoto Masayuki TerashimaHyuma Masu Mayumi NabetaKaori Ono Nobuyoshi MoritaKosuke Katagiri Isao AzumayaOsamu Tamura 《Tetrahedron》2011,67(44):8536-8543
A series of cis-preferential aromatic N-methyl amides was designed and synthesized, and acid-induced conformational alteration of these compounds was investigated by means of NMR measurements in solution and X-ray crystal structure analysis. Compounds with a terminal N-methyl-N-(2-pyridyl) amide unit showed acid-induced conformational change from cis to trans, while those with a terminal N-methyl-2-pyridinecarboxamide unit showed a change of the carbonyl orientation from anti to syn with retention of cis conformation. 相似文献
185.
We propose a conformational search method to find a global minimum energy structure for protein systems. The simulated annealing is a powerful method for local conformational search. On the other hand, the genetic crossover can search the global conformational space. Our method incorporates these attractive features of the simulated annealing and genetic crossover. In the previous works, we have been using the Monte Carlo algorithm for simulated annealing. In the present work, we use the molecular dynamics algorithm instead. To examine the effectiveness of our method, we compared our results with those of the normal simulated annealing molecular dynamics simulations by using an α-helical miniprotein. We used genetic two-point crossover here. The conformations, which have lower energy than those obtained from the conventional simulated annealing, were obtained. 相似文献
186.
Pyrimidine base pairs in DNA duplexes selectively capture metal ions to form metal ion-mediated base pairs, which can be evaluated by thermal denaturation, isothermal titration calorimetry, and nuclear magnetic resonance spectroscopy. In this critical review, we discuss the metal ion binding of pyrimidine bases (thymine, cytosine, 4-thiothymine, 2-thiothymine, 5-fluorouracil) in DNA duplexes. Thymine-thymine (T-T) and cytosine-cytosine (C-C) base pairs selectively capture Hg(II) and Ag(I) ions, respectively, and the metallo-base pairs, T-Hg(II)-T and C-Ag(I)-C, are formed in DNA duplexes. The metal ion binding properties of the pyrimidine-pyrimidine pairs can be changed by small chemical modifications. The binding selectivity of a metal ion to a 5-fluorouracil-5-fluorouracil pair in a DNA duplex can be switched by changing the pH of the solution. Two silver ions bind to each thiopyrimidine-thiopyrimidine pair in the duplexes, and the duplexes are largely stabilized. Oligonucleotides containing these bases are commercially available and can readily be applied in many scientific fields (86 references). 相似文献
187.
Uyama A Yamazoe S Shigematsu S Morimoto M Yokojima S Mayama H Kojima Y Nakamura S Uchida K 《Langmuir : the ACS journal of surfaces and colloids》2011,27(10):6395-6400
By alternate UV and visible light irradiation, reversible topographical changes were observed on a newly synthesized diarylethene microcrystalline surface between the rough crystalline surface of an open-ring isomer and flat eutectic surfaces. The contact angle changes of a water droplet between 80° and 150° and peak intensities changes of the open-ring isomer in XRD patterns within 2 h of repeating cycle were observed. The results indicated that reversibly photogenerated rod-shaped crystals on the surface were produced based on the lattice of the open-ring isomer crystals in the subphase. 相似文献
188.
Atsunori Ono Yohei Takahashi Sumio Kato Masataka Ogasawara Takashi Wakabayashi Yuunosuke Nakahara Shinichi Nakata 《Research on Chemical Intermediates》2011,37(9):1225-1230
A10(PO4)6(OH)2 (A = Ca and Sr)-supported Pt catalysts were prepared and their catalytic activity in NO reduction were investigated. The Sr10(PO4)6(OH)2-supported catalyst had high catalytic activity in the C3H6?CNO?CO2 reaction; the activity was higher than that of the ??-Al2O3-supported catalyst at 300 °C. The basicity of the apatite supports would affect the chemical state of Pt on catalyst, resulting in promotion of NO reduction. 相似文献
189.
Miura S Nishizawa S Suzuki A Fujimoto Y Ono K Gao Q Teramae N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(50):14104-14110
A surface plasmon resonance (SPR) biosensor that carries DNA-binding small ligands has been developed for the detection of single-nucleotide polymorphisms (SNPs). 3,5-Diaminopyrazine derivatives, with a hydrogen-bonding profile fully complementary to the thymine base, were utilized as recognition elements on the sensor surface, and a target single-stranded DNA sequence was hybridized with a DNA probe containing an abasic site to place this site opposite a nucleobase to be detected. In a continuous flow of sample solutions buffered to pH 6.4 (0.25 M NaCl), the 3,5-diaminopyrazine-based SPR sensor can detect an orphan nucleobase in the duplex with a clear selectivity for thymine over cytosine, guanine, and adenine (5'-GTT GGA GCT GXG GGC GTA GGC-3'/3'-CAA CCT CGA CNC CCG CAT CCG-5'; X=abasic site, N=target nucleobase G, C, A, or T). The SPR response was linear in the concentration range 10-100 nM. Allele discrimination is possible based on the combination of different binding surfaces in a flow cell of the SPR system, which is demonstrated for the analysis of the thymine/cytosine mutation present in 63-meric polymerase chain reaction (PCR) amplification products (Ha-ras gene, codon 12, antisense strand). Comparison with a bulk assay based on 3,5-diaminopyrazine/DNA binding shows that the immobilization of 3,5-diaminopyrazine derivatives on the SPR sensor allows more sensitive detection of the target DNA sequence, and binding selectivity can be tuned by controlling the salt concentration of sample solutions. These features of the DNA-binding small-molecule-immobilized SPR sensor are discussed as a basis for the design of SPR biosensors for SNP genotyping. 相似文献
190.
Kurihara H Lu X Iiduka Y Mizorogi N Slanina Z Tsuchiya T Akasaka T Nagase S 《Journal of the American Chemical Society》2011,133(8):2382-2385
Unambiguous X-ray crystallographic results of the carbene adduct of Sc(2)C(82) reveal a new carbide cluster metallofullerene with the unexpected C(2v)(5)-C(80) cage, that is, Sc(2)C(2)@C(2v)(5)-C(80). More interestingly, DFT calculations and NMR results disclose that the dynamic motion of the internal Sc(2)C(2) cluster depends strongly on temperature. At 293 K, the cluster is fixed inside the cage with two nonequivalent Sc atoms on the mirror plane, thereby leading to C(s) symmetry of the whole molecule. However, when the temperature increases to 413 K, the (13)C and (45)Sc NMR spectra show that the cluster rotates rapidly inside the C(2v)(5)-C(80) cage, featuring two equivalent Sc atoms and weaker metal-cage interactions. 相似文献