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21.
An estimation, using a Raman spectroscopic technique, of the Young’s modulus of a single filament of bacterial cellulose is
presented. This technique is used to determine the local molecular deformation of the bacterial cellulose via a shift in the
central position of the 1095 cm–1 Raman band, which corresponds to the stretching of the glycosidic bond in the backbone of the cellulose structure. By calculating
the shift rate with respect to the applied strain it is shown that the stiffness of a single fibril of bacterial cellulose
can be estimated. In order to perform this estimation, networks of fibres are rotated through 360° and the intensity of the
1095 cm−1 Raman band is recorded. It is shown that the intensity of this band is largely independent of the angle of rotation, which
suggests that the networks are randomly distributed. The modulus is predicted from a calibration of Raman band shift against
modulus, using previously published data, and by using Krenchel analysis to back-calculate the modulus of a single fibril.
The value obtained (114 GPa) is higher than previously reported values for this parameter, but lower than estimates of the
crystal modulus of cellulose-I (130–145 GPa). Reasons for these discrepancies are given in terms of the crystallinity and
structural composition of the samples. 相似文献
22.
Hayate Saito Dr. Keisuke Nogi Prof. Dr. Hideki Yorimitsu 《Angewandte Chemie (International ed. in English)》2018,57(34):11030-11034
The catalytic ring‐opening silylation of benzofurans has been achieved by employing a copper catalyst and 1,2‐di‐tert‐butoxy‐1,1,2,2‐tetramethyldisilane, which could be easily prepared and handled without special care. The reaction afforded (E)‐o‐(β‐silylvinyl)phenols with complete stereoselectivity. The scope of benzofurans was well explored, and functional groups such as chloro, fluoro, and acetal were compatible with the reaction conditions. DFT calculations were used to determine the energy profile of the silylation and the origin of the stereoselectivity. The silylated product was proven to be useful as a synthetic intermediate and subsequently underwent transformations such as Pd‐catalyzed cross‐coupling with iodoarenes. 相似文献
23.
Fukui Takehisa Ohara Satoshi Naito Makio Nogi Kiyoshi 《Journal of nanoparticle research》2001,3(2-3):171-174
LSM(La(Sr)MnO3)/YSZ(Y2O3 stabilized ZrO2) composite cathode for Solid Oxide Fuel Cells (SOFCs) was fabricated by using the composite particle consisting of well-dispersed nano-size grains of LSM and YSZ. The composite cathode had a porous structure as well as uniformly dispersed fine LSM and YSZ grains. Such unique morphology of the composite cathode led high electrochemical activity at 800°C. It suggests that the intermediate temperature (less than 800°C) operation of SOFCs will be achieved by using composite particles. 相似文献
24.
25.
ABSTRACTWe have isolated several poly 3-hydroxybutyrate-co-3-hydroxyhexanoate (PHBH) degradable bacteria from the deep-sea sediment samples. The isolated microbes were involved into α-, γ- Proteobacteria group and the phylum Firmicutes, which were commonly diverged in the ocean environment. Four bacterial strains, Bacillus sp. MH10, Alteromonas sp. MH53, Psychrobacillus sp. PL87 and Rheinheimera sp. PL100, were selected as more active strains for the PHBH bio-degradation at high pressure and cold temperature conditions, and showed that those strains were piezotolerant up to 20–30?MPa. Our findings indicated that the PHBH could be well degraded not only in the ocean environment, but also at the deep-sea bottom, by means of those marine microorganisms. 相似文献
26.
Assistant Prof. Etsuro Yamada Assistant Prof. Terukazu Ota 《Heat and Mass Transfer》1980,13(1-2):27-37
Measurements have been made by the comparison method for the effective thermal conductivity of dispersed materials which consist of substances with different thermal conductivities. The applicability of existing predicting formulae is discussed in detail as comparing their predicted values with the present data. A new predicting formula is proposed through analyzing the experimental data, the numerical results, and also the data obtained with the electrolytic-bath. It is found that the proposed formula has a wider range of applicability than that of previously reported ones. 相似文献
27.
Fujihara T Nogi K Xu T Terao J Tsuji Y 《Journal of the American Chemical Society》2012,134(22):9106-9109
Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide has been developed. The reactions proceeded under a CO(2) pressure of 1 atm at room temperature in the presence of nickel catalysts and Mn powder as a reducing agent. Various aryl chlorides could be converted to the corresponding carboxylic acid in good to high yields. Furthermore, vinyl chlorides were successfully carboxylated with CO(2). Mechanistic study suggests that Ni(I) species is involved in the catalytic cycle. 相似文献
28.
K. Matsuishi K. Nogi J. Ohmori S. Onari T. Arai 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):530-533
The effect of confinement on the structural phase of Se clusters in zeolites (LTA and FAU) has been studied in the temperature range of 300 ~ 550K by Raman scattering and differential scanning calorimetry. It has been found in Raman spectra that the structural unit and phase stability of Se clusters are greatly affected by the geometrical restriction in the zeolites. No clear phase transformation was observed by DSC measurements for Se clusters in LTA zeolites, while Se clusters in FAU zeolites exhibit a distinct endothermic peak which is ascribed to a glass transition. The glass transition temperature of amorphous Se (320 K) is remarkably elevated when Se rings/chains are incorporated in FAU zeolites; the higher glass transition temperature for the smaller window diameter of zeolites. We have also found that the activation energy for the glass transition is decreased drastically in the zeolites; the smaller activation energy for the smaller window size. The observations imply that the kinetics of the structural relaxation at the glass transition of Se is significantly influenced by the absence of inter-cluster interaction and that the thermokinetic dimension becomes lower owing to the geometrical restriction in the zeolites. 相似文献
29.
Sulfoxide-promoted ortho-C–H functionalization reactions of aromatic compounds have emerged as powerful tools for organic synthesis. Among them, [3,3] sigmatropic rearrangement induced by interrupted Pummerer reaction or electrophilic activation of sulfoxides has proved to be a fruitful strategy due to its versatility and high reaction efficiency. This digest paper mainly focuses on recent progress on C–H functionalization reactions of aryl sulfoxides via [3,3] sigmatropic rearrangement of sulfonium-tethered intermediates. 相似文献
30.
We have performed low-temperature scanning tunneling microscopy (STM) experiments on the cold-cleaved surface of YBa2Cu3Oy single crystals to study the nanoscale electronic order in high-Tc superconductors. STM images measured at low-bias voltage below ∼50 meV show the one-dimensional (1D) electronic modulation along the Cu-O bonds (parallel to the b-axis). The 1D electronic modulation does not have long-range order and the periodicity along the a-axis varies within the range ∼2a-4a depending on the position on the surface, indicating the glassy electronic order in the underdoped CuO2 plane. 相似文献