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71.
Mikael Mohtaschemi Katarina Dimic-Misic Antti Puisto Marko Korhonen Thaddeus Maloney Jouni Paltakari Mikko J. Alava 《Cellulose (London, England)》2014,21(3):1305-1312
This paper discusses the practical application of a bucket vane viscometer in the characterization of novel nanofibrillated cellulose suspensions. Specifically, we use two different grades of nanocellulose, Masuko grinded and TEMPO oxidized ones. We work at the consistency range of 1–2.3 % w/w. We find, in agreement to more accurate rheometer based experiments, that both these materials behave in a highly non-linear manner. Thus, as we discuss in this paper, using a wide gap device necessitates the use of a correction algorithm in the conversion of the angular velocity to global shear rate to access the materials intrinsic, geometry independent, flow behavior. Furthermore, from the application viewpoint, we find that the classically measured low shear rate viscosity is not a good quantity to characterize these materials. 相似文献
72.
73.
74.
Husu H Mäkitalo J Siikanen R Genty G Pietarinen H Lehtolahti J Laukkanen J Kuittinen M Kauranen M 《Optics letters》2011,36(12):2375-2377
We introduce a concept to control the spectral and dichroic properties of metamaterials. The approach is based on anisotropic metal nanoparticles and on varying their mutual orientation in a periodic lattice. Even seemingly inconsequential changes in particle ordering strongly modify the dichroic properties of the arrays and result in either very narrow resonances or ultrabroad extinction ranges. The results arise from long-range diffractive coupling between the particles, as determined by the dependence of the array unit cell size on particle ordering. 相似文献
75.
Given a negatively curved geodesic metric space M, we study the asymptotic penetration behaviour of geodesic lines of M in small neighbourhoods of closed geodesics and of other compact convex subsets of M. We define a spiraling spectrum which gives precise information on the asymptotic spiraling lengths of geodesic lines around these objects. We prove analogs of the theorems of Dirichlet, Hall and Cusick in this context. As a consequence, we obtain Diophantine approximation results of elements of ${\mathbb{R},\mathbb{C}}$ or the Heisenberg group by quadratic irrational ones. 相似文献
76.
Tiina Nypel? Hanna Pynn?nen Monika ?sterberg Jouni Paltakari Janne Laine 《Cellulose (London, England)》2012,19(3):779-792
Nanofibrillated cellulose (NFC) is increasingly utilized in materials and biomedical applications consequently increasing
interest in the modification of its surface properties. Besides modification using polyelectrolytes and polysaccharides, NFC
can be combined with solid particles enabling formation of fibril network loaded with particles. Use of particles enabling
easy functionalization could be beneficial for the development of hybrid structures, and lead to preparation of nanocomposites
and functional materials. In order to explore interactions related to preparation of such structures, the interactions between
nanosized precipitated calcium carbonate (nanoPCC) and nanoclay particles and NFC were examined by observing adsorption of
the particles on NFC substrate using a quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy
(AFM) imaging. By a treatment with carboxymethylated cellulose (CMC), the anionicity of the NFC substrate could be increased,
providing an additional tool to affect the interplay between NFC and the inorganic particles. For slightly cationic nanoPCC
particles an increase in the anionicity of the NFC by the CMC treatment increased the affinity, while the opposite was true
for anionic nanoclay. Additionally, for interactions between nanoclay and NFC, dispersion stability was an important factor.
QCM-D was successfully used to examine the adsorption characteristics of nanoparticles although the technique is commonly
used to study the adsorption of thin polymer layers. Distinct adsorption characteristics were observed depending on the nanoparticle
used; nanoclay particles deposited as a thin layer, whereas nanoPCC particles formed clusters. 相似文献
77.
Maurel V Jouni M Baran P Onofrio N Gambarelli S Mouesca JM Djurado D Dubois L Jacquot JF Desfonds G Kulszewicz-Bajer I 《Physical chemistry chemical physics : PCCP》2012,14(4):1399-1407
Magnetic properties of a doped linear polyarylamine (PA2), whose chain includes alternating para-phenylene and meta-phenylene groups, and of two cyclic and linear model compounds (C2 and D2) were explored by pulsed-EPR nutation spectroscopy, SQUID magnetometry and DFT calculations. Stoichiometrically doped PA2 samples exhibit a pure S = 1 state (exchange coupling constant J = 18 K) with a high spin concentration (0.65) corresponding to 65% of mers bearing holes. Such properties were already observed for doped reticulated polyarylamines but are quite unusual for doped linear polyarylamines. In order to better understand the properties of PA2, model compounds C2 and D2 were also investigated: pure S = 1 spin states could also be obtained, but with higher J (respectively 57 K and 35 K) and, surprisingly, with high but still limited spin concentrations (respectively 0.77 and 0.65). 相似文献
78.
79.
Necessary and sufficient conditions for the analytic coefficients of the complex linear differential equation
(†) 相似文献
80.
Using Hart Smith’s and curvelet transforms, new necessary and new sufficient conditions for an L 2(?2) function to possess Hölder regularity, uniform and pointwise, with exponent α>0 are given. Similar to the characterization of Hölder regularity by the continuous wavelet transform, the conditions here are in terms of bounds of the transforms across fine scales. However, due to the parabolic scaling, the sufficient and necessary conditions differ in both the uniform and pointwise cases. We also investigate square-integrable functions with sufficiently smooth background. Specifically, sufficient and necessary conditions, which include the special case with 1-dimensional singularity line, are derived for pointwise Hölder exponent. Inside their “cones” of influence, these conditions are practically the same, giving near-characterization of direction of singularity. 相似文献