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71.
Over the last decade, the use of nanocellulose in advanced technological applications has been promoted both due the excellent properties of this material in combination with its renewability. In this study, multilayered thin films composed of nanofibrillated cellulose (NFC), polyvinyl amine (PVAm) and silica nanoparticles were fabricated on polydimethylsiloxane (PDMS) using a layer-by-layer adsorption technique. The multilayer build-up was followed in situ by quartz crystal microbalance with dissipation, which indicated that the PVAm-SiO(2)-PVAm-NFC system adsorbs twice as much wet mass material compared to the PVAm-NFC system for the same number of bilayers. This is accompanied with a higher viscoelasticity for the PVAm-SiO(2)-PVAm-NFC system. Ellipsometry indicated a dry-state thickness of 2.2 and 3.4 nm per bilayer for the PVAm-NFC system and the PVAm-SiO(2)-PVAm-NFC system, respectively. Atomic force microscopy height images indicate that in both systems, a porous network structure is achieved. Young's modulus of these thin films was determined by the Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) technique. The Young's modulus of the PVAm/NFC films was doubled, from 1 to 2 GPa, upon incorporation of silica nanoparticles in the films. The introduction of the silica nanoparticles lowered the refractive index of the films, most probably due to an increased porosity of the films. 相似文献
72.
We describe the catalytic activity of the first chimeric ligase containing a foldameric sequence of β- and γ-amino acids. The chimeric backbone provides for the spatial arrangement of all functional groups involved in the formation of the catalytic site to allow efficient catalysis to take place. Our finding indicates significant progress in the field of functionally active artificial motifs. 相似文献
73.
Rezaei M Norooz Oliaee J Moazzen-Ahmadi N McKellar AR 《Physical chemistry chemical physics : PCCP》2011,13(27):12635-12639
Infrared spectra of a carbon disulfide trimer formed in a pulsed supersonic slit-jet expansion are obtained via direct absorption of a tuneable diode laser in the region of the CS(2)ν(3) fundamental (~1535 cm(-1)). This is the first high-resolution spectroscopic observation of (CS(2))(3). Two bands sharing the same lower state are assigned to ((12)C(32)S(2))(3). These correspond to the two infrared active trimer vibrations (a parallel and a perpendicular band) of the constituent CS(2) monomer asymmetric stretches. The weaker perpendicular band is centered at 1524.613 cm(-1), shifted by -10.74 cm(-1) with respect to the free CS(2) monomer. The parallel band is centered at 1545.669 cm(-1), a vibrational shift of +10.31 cm(-1). Transitions with K≠ 3n and those with K = 0, J = odd in the ground state are absent, establishing that this trimer has D(3) symmetry. The two parameters required to define this structure are determined to be 3.811 ? for the C-C bond distance and 61.8° for the angle between a monomer axis and the plane containing the C atoms. In addition, a parallel band arising from trimers with a single (34)S substitution is observed around 1544.46 cm(-1). Together with the recently observed cross-shaped CS(2) dimer, these results indicate a tendency for CS(2) to form highly symmetric clusters. 相似文献
74.
The impact of fractional wettability on the production characteristics of a VAPEX process at the macroscale was investigated.
Conventional VAPEX experiments were conducted in a 220 Darcy random packing of glass beads in a rectangular physical model
and n-pentane was used to recover the Cold Lake bitumen from the oil-saturated model in the absence of connate water. The composition
of oil-wet beads in the packed bed was altered from completely water-wet beads to completely oil-wet beads at different proportions
of oil-wet beads mixed with water-wet beads. A substantial increase (about 40%) in the production rate of live oil was observed
during the VAPEX process when the wettability of the porous packing was entirely oil-wet beads. A critical oil-wet fraction
of 0.66 was found for the heterogeneous packing of water-wet and oil-wet beads of similar size distribution. Above this critical
composition, the live oil production rate was not affected by further increase in the proportion of the oil-wet beads. It
is believed that above this critical composition of the oil-wet beads, the crevice flow process is dominated by the continuity
of higher conductivity live oil films between particles through the oil-wet regions. Below this critical composition, the
live oil production rate increased linearly with the fraction of the oil-wet beads in the packing. The oil-wet regions favor
the live oil drainage compared to that of the water-wet regions as they enhance the rate of imbibition of the live oil from
the oil-filled pores to the vacated pores near the nominal VAPEX interface. These two factors enhance the live oil production
rate during the VAPEX process. The solvent content of the live oil, the solvent-to-oil ratio (SOR), and the residual oil saturation
did not correlate strongly with the proportion of the oil-wet beads in the packing. The average solvent content of the live
oil and the residual oil saturation were measured to be 48% by weight and 7% by volume respectively. 相似文献
75.
76.
Rock Porous Structure Characterization: A Critical Assessment of Various State-of-the-Art Techniques
Razavifar Mehdi Mukhametdinova Aliya Nikooee Ehsan Burukhin Alexander Rezaei Amin Cheremisin Alexey Riazi Masoud 《Transport in Porous Media》2021,136(2):431-456
Transport in Porous Media - The porous structure of geomaterials is of utmost importance for various industrial and natural processes. In this study, various conventional porous structure... 相似文献
77.
G.Rezaei Behbehani A.A.Saboury M.Mohebbian S.Tahmasbi Sarvestani M.Poorheravi 《中国化学快报》2009,20(11):1389-1392
Cyanide ion was studied as an inhibitor of Jack bean urease at 300 K in 30 mmol/L tris buffer,pH 7.The inhibition was investigated by isothermal titration calorimetry(ITC).The extended solvation model was used for CN~- + JBU interaction over the whole range of CN~- concentrations.The binding parameters recovered from the solvation model were attributed to the cyanide ion interaction.It was found that cyanide ion acted as a non-cooperative inhibitor of urease,and there is a set of 12±0.12 identical and in... 相似文献
78.
Hossein Motavalli Amin Rezaei Akbarieh 《International Journal of Theoretical Physics》2010,49(5):979-987
In this paper we present the exact solutions of the one-dimensional Klein-Gordon equation for the Scarf-type potential with
equal scalar and vector potentials. Exact solutions and corresponding energy eigenvalues equation are obtained using Nikiforov-Uvarov
mathematical method for the s-wave bound state. The PT-symmetry and Hermiticity for this potential are also considered. It
will be shown that the obtained results of the Scarf-type potential are reduced to the results of the well-known potentials
in the special cases. 相似文献
79.
Mohammad A. Rezaei 《Stochastic Processes and their Applications》2018,128(3):884-896
In this paper we prove that the Hausdorff -measure of is zero when for . 相似文献
80.
In a number of fcc materials such as copper or aluminum, as well as more complex materials such as twinning induced plasticity (TWIP) steels, the interaction between dislocations and other defects such as stacking faults or twins plays an important role in the hardening behavior of such materials. Interactions of dislocation and twin or stacking fault layers have been studied in this work using molecular dynamics. Depending on the material and the loading conditions, possible interaction modes include (i) penetration of the dislocation into the faulted layer, (ii) reduction of the faulted layer after interaction, (iii) growth of the faulted layer after interaction. Such studies up to this point have been performed without temperature control near zero K (0 to 2 K). In this work, we extend the previous studies to higher temperature with the help of two methods, both based on molecular dynamics (MD) modeling. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献