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排序方式: 共有211条查询结果,搜索用时 156 毫秒
151.
152.
A. Geddo Lehmann C. Sanna N. Lampis F. Congiu G. Concas L. Maritato C. Aruta A. Yu. Petrov 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(4):337-345
Thin films of La0.7Sr0.3MnO3 were grown by
molecular beam epitaxy on (001)LaAlO3 crystals. High resolution X-ray
diffraction analysis proves the presence of twins in the films at room
temperature, showing that the twin structure of the substrate which forms at
the
ferroelastic transition at TF = 813 K
served as a template for the film microstructure. Magnetic measurements
indicate a thermomagnetic irreversibility which is ascribed to the quenched
disorder related to twinning and discussed in terms of coexisting
ferromagnetic and spin disordered regions connected with the undeformed
domain cores and strained domain walls respectively. 相似文献
153.
Chillemi G Mancini G Sanna N Barone V Della Longa S Benfatto M Pavel NV D'Angelo P 《Journal of the American Chemical Society》2007,129(17):5430-5436
A quite unexpected sevenfold coordination of the hydrated Hg(II) complex in aqueous solution is revealed by an extensive study combining X-ray absorption spectroscopy (XAS) and quantum mechanics/molecular dynamics (QM/MD) calculations. As a matter of fact, the generally accepted octahedral solvation of Hg(II) ion cannot be reconciled with XAS results. Next, refined QM computations point out the remarkable stability of a heptacoordinated structure with C2 symmetry, and long-time MD simulations by new interaction potentials including many-body effects reveal that the hydrated complex has a quite flexible structure, corresponding for most of the time to heptacoordinated species. This picture is fully consistent with X-ray absorption near-edge structure experimental data which unambiguously show the preference for a sevenfold instead of a sixfold coordination. 相似文献
154.
Sanna Hokkanen Eveliina Repo Terhi Suopajärvi Henrikki Liimatainen Jouko Niinimaa Mika Sillanpää 《Cellulose (London, England)》2014,21(3):1471-1487
The aim of the present study was to investigate the adsorption properties of aminopropyltriethoxysilane (APS) modified microfibrillated cellulose (MFC) in aqueous solutions containing Ni(II), Cu(II) and Cd(II) ions. The modified adsorbents were characterized using elemental analysis, Fourier transform infrared spectroscopy, SEM and zeta potential analysis. The adsorption and regeneration studies were conducted in batch mode using various different pH values and contact times. The maximum removal capacities of the APS/MFC adsorbent for Ni(II), Cu(II), and Cd(II) ions were 2.734, 3.150 and 4.195 mmol/g, respectively. The Langmuir, Sips and Dubinin-Radushkevich models were representative to simulate adsorption isotherms. The adsorption kinetics of Ni(II) Cu(II), and Cd(II) adsorption by APS/MFC data were modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations. The results indicate that the pseudo-second-order kinetic equation and intra-particle diffusion model were adequate to describe the adsorption kinetics. 相似文献
155.
Tapio Saarinen Sanna Haavisto Anni Sorvari Juha Salmela Jukka Seppälä 《Cellulose (London, England)》2014,21(3):1261-1275
Rheology of microfibrillated cellulose (MFC) water suspensions was characterized with a rotational rheometer, augmented with optical coherence tomography (OCT). To the best of the authors’ knowledge, this is the first time the behavior of MFC in the rheometer gap was characterized by this real-time imaging method. Two concentrations, 0.5 and 1 wt% were used, the latter also with 10?3 and 10?2 M NaCl. The aim was to follow the structure of the suspensions in a rotational rheometer during the measurements and observe wall depletion and other factors that can interfere with the rheological results. The stepped flow measurements were performed using a transparent cylindrical measuring system and combining the optical information to rheological parameters. OCT allows imaging in radial direction from the outer geometry boundary to the inner geometry boundary making both the shear rate profile and the structure of the suspension visible through the rheometer gap. Yield stress and maximum wall stress were determined by start-up of steady shear and logarithmic stress ramp methods and they both reflected in the stepped flow measurements. Above yield stress, floc size was inversely proportional to shear rate. Below the yield stress, flocs adhered to each other and the observed apparent constant shear stress was controlled by flow in the depleted boundary layer. With higher ionic strength (10?2 M NaCl), the combination of yield stress and wall depletion favored the formation of vertical, cylindrical, rotating floc structures (rollers) coupled with a thicker water layer originating at the suspension—inner cylinder boundary at low shear rates. 相似文献
156.
Willem M. Albers Sanna Auer Hannu Helle Tony Munter Inger Vikholm-Lundin 《Colloids and surfaces. B, Biointerfaces》2009,68(2):193-199
Antibody Fab′-fragments have been immobilised on hydrophilic gold by direct self-assembly, and embedded in a matrix of non-ionic hydrophilic polymers, tris(hydroxymethyl)methylacrylamide, carrying lipoate terminal linking groups. Different polymers were synthesised, and co-adsorbed or post-adsorbed between the antibody fragments in order to optimise the antigen binding. Various factors were investigated that influence the activity of the immobilised Fab′-fragments for binding of the antigen, human IgG. The Fab′-fragments were immobilised in dense layers close to monolayer coverage, and the stoichiometric efficiency of immobilisation was up to 30%, with the human IgG also approaching monolayer coverage. The cleaning of the gold surface was a crucial factor in preservation of activity. Besides the usual treatment in hot ammonia/peroxide solution, hot DMSO appeared to be highly effective as a cleaning agent. 相似文献
157.
Antti?Laakso Mihail?Dumitrescu Jukka?Viheri?l? Jarkko?Telkk?l? Juha?Tommila Kimmo?Haring Tomi?Leinonen Sanna?Ranta Markus?Pessa 《Optical and Quantum Electronics》2009,41(1):11-16
The paper presents a simulation-based analysis of laterally-corrugated ridge-waveguide distributed feedback semiconductor
lasers emitting at 980 nm. The simulations were performed using software developed in-house and the PICS3D software package
from Crosslight Software Inc. The effects of the corrugation geometry, phase-shift section, and mirror reflectivities on single
longitudinal mode operation are discussed. The lasers, designed along the guidelines derived from the simulation results,
were fabricated by using molecular beam epitaxy for wafer growth and low-cost nano-imprint lithography. They exhibited stable
single-mode operation with up to 50 dB side-mode suppression ratio. 相似文献
158.
159.
Dr. Giuseppe Di Natale Dr. Katalin Ősz Dr. Csilla Kállay Dr. Giuseppe Pappalardo Dr. Daniele Sanna Prof. Giuseppe Impellizzeri Prof. Imre Sóvágó Prof. Enrico Rizzarelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3751-3761
Characterization of the copper(II) complexes formed with the tetraoctarepeat peptide at low and high metal‐to‐ligand ratios and in a large pH range, would provide a breakthrough in the interpretation of biological relevance of the different metal complexes of copper(II)‐tetraoctarepeat system. In the present work, the potentiometric, UV/Vis, circular dichroism (CD), and electron paramagnetic resonance (EPR) studies were carried out on copper(II) complexes with a PEG‐ylated derivative of the tetraoctarepeats peptide sequence (Ac‐PEG27‐(PHGGGWGQ)4‐NH2) and the peptide Ac‐(PHGGGWGQ)2‐NH2. Conjugation of tetraoctarepeat peptide sequence with polyethyleneglycol improved the solubility of the copper(II) complexes. The results enable a straightforward explanation of the conflicting results originated from the underestimation of all metal–ligand equilibria and the ensuing speciation. A complete and reliable speciation is therefore obtained with the released affinity and binding details of the main complexes species formed in aqueous solution. The results contribute to clarify the discrepancies of several studies in which the authors ascribe the redox activity of copper(II)‐tetraoctarepeat system considering only the average effects of several coexisting species with very different stoichiometries and binding modes. 相似文献
160.
Valeria Alzari Daniele Nuvoli Roberta Sanna Laura Peponi Massimo Piccinini Silvia Bittolo Bon Salvatore Marceddu Luca Valentini Jose Maria Kenny Alberto Mariani 《Colloid and polymer science》2013,291(11):2681-2687
Nanocomposite hydrogels of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) containing graphene were prepared by radical polymerization. Their swelling properties in response to ionic strength and electrical stimuli were assessed. Graphene was obtained through an easy and convenient method lately developed by our research group, which consists in the exfoliation of graphite by sonicating it in a proper solvent medium. It was found that the graphene content influences the swelling properties of hydrogels; in particular, those containing graphene swell more than the filler-free ones; graphene content influences also the swelling ratio variation between the swollen and deswollen states. 相似文献