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1.
Kotel'nikova N. E. Wegener G. Paakkari T. Serimaa R. Demidov V. N. Serebriakov A. S. Shchukarev A. V. Gribanov A. V. 《Russian Journal of General Chemistry》2003,73(3):418-426
Diffusion of silver ions into a cellulose matrix and their subsequent reduction both with the matrix itself and with specific reducers lead to preparation of cellulose materials containing silver(0). Most silver metal is intercalated into the cellulose matrix when glycerol is used as solvent and potassium hypophosphite or sodium boron hydrate are used as reducers. 相似文献
2.
Pirita Rämänen Paavo A. Penttilä Kirsi Svedström Sirkka Liisa Maunu Ritva Serimaa 《Cellulose (London, England)》2012,19(3):901-912
Cellulose whiskers were prepared from wood- and cotton-based microcrystalline cellulose and dried by two methods: freeze-drying
or air-drying. The effect of drying method on the properties and structure of the whiskers were studied. Furthermore, the
influence of the source of cellulose on the nanoscale structure was investigated. Drying method was observed to slightly influence
the thermal stability of cellulose whiskers, whereas the char residue varied significantly depending on the drying process
performed. Small- and wide-angle X-ray scattering and solid state nuclear magnetic resonance spectroscopy were used to examine
the crystallinity and nanoscale structure of the dried whiskers. It was observed that the crystal structure and crystallinity
of cellulose whiskers remained during all treatments, whereas their nanoscale structure was significantly influenced by drying
method, neutralization, and source of cellulose. Relationships between thermal behavior and nanoscale structure were reported
and discussed. 相似文献
3.
Nikolaos Pahimanolis Arto Salminen Paavo A. Penttilä Juuso T. Korhonen Leena-Sisko Johansson Janne Ruokolainen Ritva Serimaa Jukka Seppälä 《Cellulose (London, England)》2013,20(3):1459-1468
In this paper, nanofibrillated cellulose/carboxymethyl cellulose (CMC) composite films were prepared using tape casting. The obtained transparent films showed shear induced partial alignment of fibrils along the casting direction, resulting in birefringence in cross polarized light. The carboxyl groups of CMC could be further utilized to create ionic crosslinking by treatment with glycidyl trimethyl ammonium chloride (GTMA). The GTMA treated composite films had improved mechanical properties both in wet and dry state. The chemical composition and morphologies of composites were analyzed with X-ray photoelectron spectroscopy, elemental analysis, scanning electron microscopy and wide-angle X-ray scattering. 相似文献
4.
U. Vainio K. Pirkkalainen K. Kisko G. Goerigk N. E. Kotelnikova R. Serimaa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(1):93-101
Microcrystalline cellulose is a porous natural material which
can be used both as a support for nanoparticles and as a reducer of metal ions.
Cellulose supported nanoparticles can act as catalysts in many reactions.
Cu, CuO, and Cu2O particles were prepared in microcrystalline cellulose
by adding a solution of copper salt
to the insoluble cellulose matrix and by reducing the copper ions
with several reducers.
The porous nanocomposites were studied using anomalous small angle X-ray
scattering (ASAXS), X-ray absorption spectroscopy, and X-ray diffraction.
Reduction of Cu2+ with cellulose in ammonium hydrate medium
yielded crystalline CuO nanoparticles and
the crystallite size was about 6–20 nm irrespective of
the copper concentration. The size distribution of the CuO particles
was determined with ASAXS measurements and
coincided with the crystallite sizes.
Using sodium borohydrate or hydrazine sulfate as a reducer
both metallic Cu and Cu2O nanoparticles
were obtained and the crystallite size and the oxidation state
depended on the amount of reducer. 相似文献
5.
N. E. Kotelnikova E. F. Panarin R. Serimaa T. Paakkari G. Wegener E. Windeisen 《Macromolecular Symposia》1999,138(1):181-189
In order to obtain multicomponent polymer systems exhibiting biological activity microcrystalline cellulose was used as a matrix for biologically active compounds, such as dimethylbenzylalkylammonium chloride, poly-N-vinylpyrrolidone, copolymer of N-vinylpyrrolidone and crotonic acid, and complex of dimethylbenzylalkylammonium chloride with copolymer of N-vinylpyrrolidone and crotonic acid. Adsorption interaction of microcrystalline cellulose with these was studied under various conditions. Adsorption isotherms of compounds of polymer nature are of similar character and are described by the Freundlich equation. The isotherms of dimethylbenzylalkylammonium chloride are described by the Langmuir equation. Characteristics of the resulting compounds were obtained using XPS and IR Fourier spectroscopy, WAXS, and SEM. Chemical interaction between microcrystalline cellulose and dimethylbenzylalkylammonium chloride takes place. This interaction leads to a new labile morphological cellulose structure accessible to penetration, which is confirmed at a morphological level by SEM. 相似文献
6.
Mika Torkkeli Ritva Serimaa Veli Etelniemi Minna Toivola Kaija Jokela Mikael Paronen Franciska Sundholm 《Journal of Polymer Science.Polymer Physics》2000,38(13):1734-1748
Small‐angle and wide‐angle X‐ray scattering and anomalous small‐angle X‐ray scattering were used to investigate proton‐conducting membranes prepared by radiation‐induced styrene grafting and sulfonation of commercial poly(vinylidene fluoride) (PVDF‐g‐PS) films. The membranes retain the lamellar and highly oriented structure of the original PVDF films even through excessive grafting and sulfonation. The sulfonate groups aggregate in the central part of the amorphous layers, where they form a weakly ordered structure that does not show any preferred orientation. This structure is suggested to be lamellar with alternate metal‐sulfonated hydrate and PVDF‐g‐PS layers. The lamellar period is 15.1 Å. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1734–1748, 2000 相似文献
7.
Hydrophobins are small fungal proteins, which have remarkable surface-chemical properties. They self-assemble at hydrophobic/hydrophilic interfaces and work as adhesive agents and coatings. Sixteen layer Langmuir-Blodgett films of hydrophobins HFBI and HFBII from the fungus Trichoderma reesei were prepared and studied using grazing-incidence X-ray diffraction and reflectivity techniques. Both kind of films contain hexagonally ordered crystallites on the substrate with unit cell parameters of a = b = 54 Å (HFBI) and a = b = 55 Å (HFBII). The structure is similar to the structure of monolayer Langmuir-Blodgett films. 相似文献
8.
We show that fractional (p, p)-Poincaré inequalities and even fractional Sobolev-Poincaré inequalities hold for bounded John domains, and especially for bounded Lipschitz domains. We also prove sharp fractional (1,p)-Poincaré inequalities for s-John domains. 相似文献
9.
Noora Ristolainen Ulla Vainio Santeri Paavola Mika Torkkeli Ritva Serimaa Jukka Seppl 《Journal of Polymer Science.Polymer Physics》2005,43(14):1892-1903
The properties of polypropylene composites can be tailored through the use of nanoclay fillers. The effectiveness of a metallocene‐catalyzed hydroxyl‐functional polypropylene in the compatibilization of polypropylene layered nanosilicate composites was studied, and the results were compared with those for a commercial maleic anhydride functionalized polypropylene. Polypropylene/organoclay nanocomposites were prepared by melt blending, and two polypropylene/compatibilizer/organoclay ratios, 90/5/5 and 70/20/10, were characterized. The organomodification of the clay was carried out with octadecylamine and N‐methylundecenylamine. The structure of the layered silicate was studied by transmission electron microscopy, wide‐angle X‐ray scattering, and small‐angle X‐ray scattering. The fracture surfaces of the composites and thus the efficiency of the compatibilizers to penetrate the galleries of the organoclays were characterized by scanning electron microscopy, and the melt viscosity was studied by stress‐controlled rotational rheometry. The nanostructure was observed with both alkyl amines used for intercalation. The fillers facilitated the processability of all the composites, consisting of equal amounts of compatibilizer and organoclay filler and, in some of the composites, containing twice as much compatibilizer as organoclay filler. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1892–1903, 2005 相似文献
10.
We identified and characterized two genes, LAT1 and LAT2, which encode specific l-arabinose transporters. The genes were identified in the l-arabinose fermenting yeast Ambrosiozyma monospora. The yeast Saccharomyces cerevisiae had only very low l-arabinose transport activity; however, when LAT1 or LAT2 was expressed, l-arabinose transport was facilitated. When the LAT1 or LAT2 were expressed in an S. cerevisiae mutant where the main hexose transporters were deleted, the l-arabinose transporters could not restore growth on d-glucose, d-fructose, d-mannose or d-galactose. This indicates that these sugars are not transported and suggests that the transporters are specific for l-arabinose. 相似文献