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991.
Yasutaka Kuwahara Keiichi Maki Takashi Kamegawa Kohsuke Mori Hiromi Yamashita 《Topics in Catalysis》2009,52(1-2):193-196
Through the simple process using alkoxide reagent containing fluorine, triethoxyfluorosilane (TEFS), hydrophobic mesoporous silica material (HMS) was prepared. The surface modified HMS have still maintained its mesoporous structure and large surface area and showed considerable hydrophobic property compared with non-modified HMS. Moreover the surface modified HMS was applied as a support of TiO2 photocatalyst with the aim of the efficient degradation of organic pollutant in water. Due to the hydrophobic property, the fine TiO2 photocatalyst particles were generated on the modified HMS and both the adsorption properties and photocatalytic activities for the degradation of 2-propanol diluted in water were dramatically increased. 相似文献
992.
Shinji Kudo Taisuke Maki Masahiro Yamada Kazuhiro Mae 《Chemical engineering science》2010,65(1):214-219
A new preparation method of Au/α-Fe2O3 catalyst for CO oxidation reaction was proposed in this paper. The method includes only a simple modification of the conventional coprecipitation method, adding HAuCl4 solution after the growth of iron hydroxide grain to a certain size, but significantly influenced the catalytic activity in the reaction. In the characterization study, XRD (X-ray diffractometer) analysis, TEM (transmission electron microscope) observation, and N2 adsorption measurement showed similar results among the samples calcined at the same temperature, but the effect of the preparation method appeared in the CO adsorption measurement among the samples calcined at 200 °C. Catalysts having high CO adsorption ability also performed well in CO oxidation tests. The CO adsorption and oxidation studies indicated that the proposed preparation method results in stable and effective loading of Au, compared to the conventional coprecipitation method. In the CO oxidation test, the catalyst prepared by the proposed mixing scheme achieved complete CO conversion for more than 3000 h at 25 °C, space velocity 100,000 h?1, and 500 ppm CO. The selectivity for the CO oxidation was confirmed using reformed gas containing excess H2. In addition, the NO reduction reaction was favored over CO oxidation by the catalyst. Thus, we were able to load Au on the α-Fe2O3 effectively and demonstrate its potential as an environmental catalyst. 相似文献
993.
S. Hashimoto S. Horita Y. Ito H. Hirano S. Honda Y. Iwamoto 《Journal of the European Ceramic Society》2010,30(3):635-639
A porous alumina body was synthesized from anisotropic alumina particles (platelets). The uniaxial pressure in fabricating the green compact body had an influence on the relative density of the alumina body after heating. When green compacts, which had been uniaxially pressed at 1 and 3 MPa, were heated at 1400 °C for 1 h, the relative densities of the resulting alumina bodies were 25.0% and 35.5%, respectively. The compressive strength of compacts that were uniaxially pressed at 1 and 3 MPa were 0.8 and 4.3 MPa, respectively. In an attempt to increase the compressive strength of these porous alumina bodies, aluminum nitrate and magnesium nitrate solution treatments were performed, followed by reheating to 1400 °C for 1 h. When a 0.5 mol/l aluminum nitrate solution was used, the compressive strength of the porous alumina body uniaxially pressed at 1 MPa changed from 0.8 MPa (without solution treatment) to 1.5 MPa. Furthermore, when 0.1 mol/l magnesium nitrate solution was used, the compressive strength of the porous alumina increased to 1.7 MPa. Thus, solution treatment of the porous alumina body had a strong positive effect on its mechanical strength. 相似文献
994.
Saba Samatya Hidenobu Mizuki Yudai Ito Hidetaka Kawakita Kazuya Uezu 《Reactive and Functional Polymers》2010,70(1):63-68
A novel adsorbent, Zr(IV)-immobilized resin, was prepared by surface template polymerization. This adsorbent, prepared by adding polystyrene (PS) to resin, has a high adsorption capacity for the removal of fluoride ion from aqueous solutions. The adsorption capacity increased with rising PS concentration, since the specific surface area can be effectively increased by adding polystyrene as a porogen. The adsorption isotherm has been modeled by the Langmuir and Freundlich equations. The adsorption isotherms were well described by the Langmuir equation. The removal of fluoride was also carried out using a column method. The presence of PS in the resin exerted a remarkable influence on the uptake of fluoride ion. The fluoride adsorbed on the resin was quantitatively eluted with 0.1 M NaOH. 相似文献
995.
Nishikawa I Nakajima Y Ito M Fukuchi S Homma K Nishikawa K 《International journal of molecular sciences》2010,11(12):4991-5008
O-glycosylation of mammalian proteins is one of the important posttranslational modifications. We applied a support vector machine (SVM) to predict whether Ser or Thr is glycosylated, in order to elucidate the O-glycosylation mechanism. O-glycosylated sites were often found clustered along the sequence, whereas other sites were located sporadically. Therefore, we developed two types of SVMs for predicting clustered and isolated sites separately. We found that the amino acid composition was effective for predicting the clustered type, whereas the site-specific algorithm was effective for the isolated type. The highest prediction accuracy for the clustered type was 74%, while that for the isolated type was 79%. The existence frequency of amino acids around the O-glycosylation sites was different in the two types: namely, Pro, Val and Ala had high existence probabilities at each specific position relative to a glycosylation site, especially for the isolated type. Independent component analyses for the amino acid sequences around O-glycosylation sites showed the position-specific existences of the identified amino acids as independent components. The O-glycosylation sites were preferentially located within intrinsically disordered regions of extracellular proteins: particularly, more than 90% of the clustered O-GalNAc glycosylation sites were observed in intrinsically disordered regions. This feature could be the key for understanding the non-conservation property of O-glycosylation, and its role in functional diversity and structural stability. 相似文献
996.
Hiroaki Sasaki Nobuo Donkai Hiraku Ito Katustoshi Imamura Hideaki Morikawa 《Coloration Technology》2000,116(11):349-351
The dyeing properties were investigated for silk proteins produced by silkworms reared entirely on an artificial diet (A) and a mulberry leaf diet (M). The dyeing experiments were carried out with CI acid orange 7 at pH 3.9 and 60°C. The sericin contents of the A and the M raw silk samples were determined to be 26.0% and 23.7%, respectively. The equilibrium dye uptake and the dyeing rate of the A silk fibroin were almost the same as those of the M silk fibroin. The equilibrium dye uptake on each silk sericin was 3–4 times higher than that of the silk fibroin. On the other hand, the equilibrium dye uptake of the A silk sericin was higher than that of the M silk sericin, but the dyeing rate of the former was slower than that of the latter. 相似文献
997.
Takuya Ito Dr. Niran Roongsawang Dr. Norifumi Shirasaka Dr. Wanli Lu Patricia M. Flatt Dr. Noer Kasanah Dr. Cristobal Miranda Dr. Taifo Mahmud Prof. Dr. 《Chembiochem : a European journal of chemical biology》2009,10(13):2253-2265
Pactamycin is an aminocyclopentitol‐derived natural product that has potent antibacterial and antitumor activities. Sequence analysis of an 86 kb continuous region of the chromosome from Streptomyces pactum ATCC 27456 revealed a gene cluster involved in the biosynthesis of pactamycin. Gene inactivation of the Fe‐S radical SAM oxidoreductase (ptmC) and the glycosyltransferase (ptmJ), individually abrogated pactamycin biosynthesis; this confirmed the involvement of the ptm gene cluster in pactamycin biosynthesis. The polyketide synthase gene (ptmQ) was found to support 6‐methylsalicylic acid (6‐MSA) synthesis in a heterologous host, S. lividans T7. In vivo inactivation of ptmQ in S. pactum impaired pactamycin and pactamycate production but led to production of two new pactamycin analogues, de‐6‐MSA‐pactamycin and de‐6‐MSA‐pactamycate. The new compounds showed equivalent cytotoxic and antibacterial activities with the corresponding parent molecules and shed more light on the structure–activity relationship of pactamycin. 相似文献
998.
Electrochemical copolymerization of aniline and aniline-2,5-disulfonic acid (ADSA) was carried out in HCl solutions. The presence of ADSA inhibited significantly the growth of polyaniline (PAn), although the voltammetry of the copolymer was still similar to that of conventional PAn. As the ADSA concentration increased, the deposition rate of the copolymer decreased rapidly and finally no solid film was deposited on the electrode surface. When the ADSA concentration was lower than ˜ 5 mM, the depression effect of ADSA on the growth rate of the copolymer is mainly due to its stronger adsorption at the electrode surface. For higher ADSA concentrations, the inhibiting effect of ADSA was dominated by its termination effects, which led to more soluble oligomers and in turn resulted in lower deposition efficiency. Electrolysis of ADSA solution might result in a water-soluble fully sulfonated PAn. 相似文献
999.
High-resolution crystal structure of M-protease: phylogeny aided analysis of the high-alkaline adaptation mechanism 总被引:2,自引:0,他引:2
Shirai T; Suzuki A; Yamane T; Ashida T; Kobayashi T; Hitomi J; Ito S 《Protein engineering, design & selection : PEDS》1997,10(6):627-634
M-protease is a subtilisin-family serine protease produced by an
alkaliphilic Bacillus sp. strain. Optimal enzymatic activity of the protein
occurs at pH 12.3. The crystal structure of M-protease (space group
P2(1)2(1)2(1), a = 62.3, b = 75.5, c = 47.2 A) has been refined to a
crystallographic R-factor of 17.2% at 1.5 A resolution. The alkaline
adaptation mechanism of the enzyme was analyzed. Molecular phylogeny
construction was used to determine the amino acid substitutions that
occurred during the high-alkaline adaptation process. This analysis
revealed a decrease in the number of negatively charged amino acids
(aspartic acid and glutamic acid) and lysine residues and an increase in
arginine and neutral hydrophilic amino acids (histidine, asparagine and
glutamine) residues during the course of adaptation. These substitutions
increased the isoelectric point of M- protease. Some of the acquired
arginine residues form hydrogen bonds or ion pairs to combine both N- and
C-terminal regions of M-protease. The substituted residues are localized to
a hemisphere of the globular protein molecule where positional shifts of
peptide segments, relative to those of the less alkaliphilic subtilisin
Carlsberg, are observed. The biased distribution and interactions caused by
the substituted residues seem to be responsible for stabilization of the
conformation in a high-alkaline condition.
相似文献
1000.
A macroporous silica-based (Calix[4]+Dodecanol)/SiO2-P absorbent for separation of Cs(I) from HNO3 solution was prepared by impregnating the 1,3-[(2,4-Diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene and its molecule modifier 1-dodecanol into a macroporous silica/polymer composite support. To establish its application into partitioning of Cs(I) from High Level Liquid Waste (HLLW), the adsorption properties and radiation effects on the adsorbent were investigated. The adsorbent showed a relatively large distribution coefficient of Cs(I) and fast equilibrium time in simulated HLLW. Additionally, the adsorbent under the gamma-ray field was found to be able to selectively adsorb Cs(I) with similar behavior to the adsorption without irradiation up to at least 170 kGy. 相似文献