排序方式: 共有45条查询结果,搜索用时 15 毫秒
1.
Marja Pitkänen Heli Kangas Ossi Laitinen Asko Sneck Panu Lahtinen Maria Soledad Peresin Jouko Niinimäki 《Cellulose (London, England)》2014,21(6):3871-3886
A finely ground fibrillated cellulose was fractionated into separate size fractions. The characteristics of the smallest size fractions were studied, and the toxicity to humans was tested as part of a safety assessment. Morphological studies performed with state-of-the-art methods, such as scanning electron microscopy and atomic force microscopy, showed that the fraction obtained consisted of long thin fibrils but also larger fibril agglomerates, and spherical particles were present. The finest fraction did not show any sub-lethal effects as assessed by RNA inhibition test in vitro, nor were there any indications of genotoxicity as tested by the Ames test in vitro. Systemic effects tested in vivo with the nematode were also absent. No cytotoxic effects were seen in the highest tolerated dose test in vitro, but some indication of cytotoxicity was observed in the total protein content test in vitro at the highest sample concentration. The significance of this toxicity test result should be addressed in relation to the other toxicity tests, in which no toxicity was observed, with special emphasis on the in vivo test. Given this, the overall toxicity analyses support the conclusion that nano-scale cellulose fibrils can be considered to be safe towards humans. However, the reason for the positive cytotoxicity test result and, in addition, the effect of the biocide used in sample preservation on the toxicity tests need to be clarified before generalizing these results and declaring nanocellulose to be unambiguously safe. 相似文献
2.
Andrea Macrelli Nicol Simone Villa Andrea Lucotti David Dellasega Paolo Maria Ossi Matteo Tommasini 《Molecules (Basel, Switzerland)》2022,27(1)
The applications of SERS in therapeutic drug monitoring, or other fields of analytical chemistry, require the availability of sensitive sensors and experimental approaches that can be implemented in affordable ways. In this contribution, we show the production of cost-effective SERS sensors obtained by depositing Lee-Meisel Ag colloids on filter paper either by natural sedimentation or centrifugation. We have characterized the morphological and plasmonic features of the sensors by optical microscopy, SEM, and UV-Vis spectroscopy. Such sensors can be used to quantify by SERS the anti-epileptic drug Perampanel (in the concentration range 1 × 10−4–5 × 10−6 M) by spinning them during the micro-Raman measurements on the top of a custom device obtained from spare part hard disk drives. This approach minimizes laser-induced heating effects and allows averaging over the spatial non-uniformity of the sensor. 相似文献
3.
P. M. Ossi F. Neri N. Santo S. Trusso 《Applied Physics A: Materials Science & Processing》2011,104(3):829-837
Silver and gold thin films were deposited by pulsed laser ablation in a controlled Ar atmosphere at pressures between 10 and
100 Pa. Different morphologies, ranging from isolated nanoparticle arrays up to nanostructured thin films were observed. Fast
imaging of the plasma allowed deducing the expansion dynamics of the ablated plume. Plasma velocity and volume were used together
with the measured average ablated mass per pulse as input parameters in a model to estimate the average size of nanoparticles
grown in the plume. The nanoparticle size is expected to decrease from 4 nm down to 1 nm with decreasing Ar pressure between
100 and 10 Pa: this was confirmed by transmission electron micrographs which indicate a reduced dispersion of particle size
over narrow size ranges. The production of substrates for surface enhanced Raman scattering whose performances critically
depend on nanoparticle size, shape, and structure is discussed. 相似文献
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Nanostructured thin films were deposited by excimer laser ablation of silver targets in controlled atmospheres of He and Ar. The film structural properties were investigated by means of scanning electron microscope and transmission electron microscope imaging. The film growth mechanism was identified as the result of coalescence of nanometric clusters formed during plume flight. Cluster formation involves plume confinement as a consequence of the increased collisional rate among plasma species. Fast photography imaging of the laser-generated silver plasma allowed to identify plasma confinement, shock wave formation and plasma stopping. 相似文献
6.
P. M. Ossi 《Il Nuovo Cimento D》1988,10(4):395-406
Summary A model for glass formation and crystal structure retainment in binary alloys undergoing irradiation by energetic ion beams
is presented. The major physical features provided by experimental conditions, namely spike formation and evolution of bombardment-induced
surface compositional variations, are taken into account. At spike-lattice interface interatomic interactions with charge
transfer occur, which induce formation of amorphization, or crystallization nuclei. Qualitative differences are found between
glass forming and crystalline systems.
To speed up publication, the author of this paper has agreed to not receive the proofs for correction. 相似文献
7.
Ossi Horovitz Gheorghe Tomoaia Csaba Racz Aurora Mocanu Liviu-Dorel Bobos Maria Tomoaia-Cotisel 《Central European Journal of Chemistry》2006,4(3):489-501
The surface pressure versus molecular area isotherms of some carotenoids: β,β-carotene-4-one (echinenone, ECH), β,β-carotene-4,4′-dione
(canthaxanthin, CAN) and 4,4′-diapo-ω,ω-carotene-4,4′-dial (APO), spread at the air/water interface, are reported. A van der
Waals type state equation is used to describe the high molecular area portions of the compression isotherms and interaction
parameters within monolayers are derived. Quantum chemical semi-empirical SCF MO calculations (AM1 and PM3) are performed
for the optimized geometries of molecules and dipole moments are calculated. Similar theoretical magnitudes are obtained by
both methods. Surface properties, like collapse pressure, surface compressional modulus and interaction parameters are discussed
in terms of dipole-dipole interactions, and correlations with the calculated quantities for the carotenoid molecules are analyzed.
The orientation of the different carotenoid molecules in the monolayer is discussed. 相似文献
8.
Cu-Cr alloys, irradiated with a low-energy, high-current electron beam, are analyzed by high-resolution secondary ion mass spectrometry. Mass spectra and images of Cu+ and Cr+ surface distributions finely reveal the regions enriched in Cu and Cr. For electron beam energies above a threshold value, the formation of a non-equilibrium Cu1−xCrx solid solution, extending over sub-micrometer areas is highlighted for the first time. A discussion of the process leading to Cu1−xCrx formation is given. 相似文献
9.
P. M. Ossi 《Zeitschrift für Physik B Condensed Matter》1988,69(4):511-519
A model of atomistic nature is presented to interpret experimental data on glass formation, as well as crystalline structure achievement, or retainment in samples undergoing ion implantation, or ion mixing.The essential features of the irradiation-induced highly nonequilibrium state created within the target, namely spike formation and evolution and surface stoichiometry alterations, form the basis of the model.In binary alloys, atoms of one kind are supposed to preferentially migrate to the surface, where the excess stoichiometry causes interatomic interactions with charge transfer to occur.The obtained effective atom pairs exhibit different surface properties from those of the starting alloys.On the basis of the above behaviour, the model allows to identify qualitative physical differences between glass forming systems and crystalline ones. 相似文献
10.
The influence of mesh motion on the quality of large eddy simulation (LES) was studied in the present article. A three‐dimensional, turbulent pipe flow (Reτ=360) was considered as a test case. Simulations with both stretching and static meshes were carried out in order to understand how mesh motion affects the turbulence statistics. The spatial filtering of static and moving mesh direct numerical simulation (DNS) data showed how an ideal LES would perform, while the comparison of DNS cases with static and moving meshes revealed that no significant numerical errors arise from the mesh motion when the simulation is fully resolved. The comparison of the filtered fields of the DNS with a moving mesh with the corresponding LES fields revealed different responses to mesh motion from different numerical approaches. A straightforward test was applied in order to verify that the moving mesh works consistently in LES: when the mesh is stretched in the streamwise direction, the moving mesh results should be in between the two extremal resolutions between which the mesh is stretched. Numerical investigations using four different LES approaches were carried out. In addition to the Smagorinsky model, three implicit LES approaches were used: linear interpolation (non‐dissipative), the Gamma limiter (dissipative), and the scale‐selective discretisation (slightly dissipative). The results indicate that while the Smagorinsky and the scale‐selective discretisation approaches produce results consistent with the resolution of the non‐static mesh, the implicit LES with linear interpolation or the Gamma scheme do not. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献