731 research outputs found
Nanomechanical and topographical imaging of living cells by Atomic Force Microscopy with colloidal probes
Atomic Force Microscopy (AFM) has a great potential as a tool to characterize
mechanical and morphological properties of living cells; these properties have
been shown to correlate with cells' fate and patho-physiological state in view
of the development of novel early-diagnostic strategies. Although several
reports have described experimental and technical approaches for the
characterization of cell elasticity by means of AFM, a robust and commonly
accepted methodology is still lacking. Here we show that micrometric spherical
probes (also known as colloidal probes) are well suited for performing a
combined topographic and mechanical analysis of living cells, with spatial
resolution suitable for a complete and accurate mapping of cell morphological
and elastic properties, and superior reliability and accuracy in the mechanical
measurements with respect to conventional and widely used sharp AFM tips. We
address a number of issues concerning the nanomechanical analysis, including
the applicability of contact mechanical models and the impact of a constrained
contact geometry on the measured elastic modulus (the finite-thickness effect).
We have tested our protocol by imaging living PC12 and MDA-MB-231 cells, in
order to demonstrate the importance of the correction of the finite-thickness
effect and the change in cell elasticity induced by the action of a
cytoskeleton-targeting drug.Comment: 51 pages, 12 figures, 3 table
Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition
Great emphasis is placed on the development of integrated approaches for the
synthesis and the characterization of ad hoc nanostructured platforms, to be
used as templates with controlled morphology and chemical properties for the
investigation of specific phenomena of great relevance for technological
applications in interdisciplinary fields such as biotechnology, medicine and
advanced materials. Here we discuss the crucial role and the advantages of thin
film deposition strategies based on cluster-assembling from supersonic cluster
beams. We select cluster-assembled nanostructured titania (ns-TiO2) as a case
study to demonstrate that accurate control over morphological parameters can be
routinely achieved, and consequently over several relevant interfacial
properties and phenomena, like surface charging in a liquid electrolyte, and
proteins and nanoparticles adsorption
Asteroid families classification: exploiting very large data sets
The number of asteroids with accurately determined orbits increases fast. The
catalogs of asteroid physical observations have also increased, although the
number of objects is still smaller than in the orbital catalogs. We developed a
new approach to the asteroid family classification by combining the
Hierarchical Clustering Method (HCM) with a method to add new members to
existing families. This procedure makes use of the much larger amount of
information contained in the proper elements catalogs, with respect to
classifications using also physical observations for a smaller number of
asteroids. Our work is based on the large catalog of the high accuracy
synthetic proper elements (available from AstDyS). We first identify a number
of core families; to these we attribute the next layer of smaller objects.
Then, we remove all the family members from the catalog, and reapply the HCM to
the rest. This gives both halo families which extend the core families and new
independent families, consisting mainly of small asteroids. These two cases are
discriminated by another step of attribution of new members and by merging
intersecting families. By using information from absolute magnitudes, we take
advantage of the larger size range in some families to analyze their shape in
the proper semimajor axis vs. inverse diameter plane. This leads to a new
method to estimate the family age (or ages). The results from the previous
steps are then analyzed, using also auxiliary information on physical
properties including WISE albedos and SDSS color indexes. This allows to solve
some difficult cases of families overlapping in the proper elements space but
generated by different collisional events. We analyze some examples of
cratering families (Massalia, Vesta, Eunomia) which show internal structures,
interpreted as multiple collisions. We also discuss why Ceres has no family
Effects of axial torsion on sp carbon atomic nanowires
Ab-initio calculations within Density Functional Theory combined with
experimental Raman spectra on cluster-beam deposited pure carbon films provide
a consistent picture of sp-carbon chains stabilized by sp^3 or sp^2
terminations, the latter being sensitive to torsional strain. This unexplored
effect promises many exciting applications since it allows one to modify the
conductive states near the Fermi level and to switch on and off the on-chain
pi-electron magnetism.Comment: in print in Phys Rev Let
Synthesis, Characterization, and Modeling of Naphthyl-Terminated sp Carbon Chains: Dinaphthylpolyynes
We report a combined study on the synthesis, spectroscopic characterization
and theoretical modelling of a series of {\alpha},{\omega}-dinaphthylpolyynes.
We synthesized this family of naphtyl-terminated sp carbon chains by reacting
diiodoacetylene and 1-ethynylnaphthalene under the Cadiot-Chodkiewicz reaction
conditions. By means of liquid chromatography (HPLC), we separated the products
and recorded their electronic absorption spectra, which enabled us to identify
the complete series of dinaphthylpolyynes Ar-C2n-Ar (with Ar = naphthyl group
and n = number of acetilenic units) with n ranging from 2 to 6. The longest
wavelength transition (LWT) in the electronic spectra of the dinaphthylpolyynes
red shifts linearly with n away from the LWT of the bare termination. This
result is also supported by DFT-LDA simulations. Finally, we probed the
stability of the dinaphthylpolyynes in a solid-state precipitate by
Fourier-transform infrared spectroscopy and by differential scanning
calorimetry (DSC).Comment: This document is the unedited Author's version of a Submitted Work
that was subsequently accepted for publication in [J. Phys. Chem. B],
copyright \c{opyright} American Chemical Society after peer review. To access
the final edited and published work see
http://pubs.acs.org/doi/abs/10.1021%2Fjp104863
Bevacizumab for Macular Serous Neuroretinal Detachment in Tilted Disk Syndrome
Background. Tilted disc syndrome (TDS) is a congenital anomaly characterized by “tilting” of the optic disc tipycally associated with myopic astigmatism, visual field defect, inferior staphyloma, and retinal pigment epithelium atrophy. Associated complications such as macular serous neuroretinal detachment are well described; however, ideal therapy for such complication is unknown. Methods. One interventional case report is hereby described. A patient affected by macular serous neuroretinal detachment-complicated tilted disk syndrome underwent a complete ophthalmic examination. Optical coherence tomography and fluorescein angiography were taken at baseline and at scheduled visits. Two intravitreal treatments of bevacizumab (avastin, 1.25 mg/0.05 mL) were performed at monthly interval. Results. At scheduled visit, one month after the second injection, OCT depicted persistence of neuroretinal detachment. Best-corrected visual acuity remain stable as well as metamorphopsia and functional discomfort. Conclusion. Clinical evidence of this brief interventional case report indicates that one patient affected by recent serous macular detachment-complicated TDS did not benefit from 2 consecutive monthly intravitreal Avastin treatments. Best-corrected visual acuity remained stable over a total observation period of 6 months
All-for-One and One-For-All: Deep learning-based feature fusion for Synthetic Speech Detection
Recent advances in deep learning and computer vision have made the synthesis
and counterfeiting of multimedia content more accessible than ever, leading to
possible threats and dangers from malicious users. In the audio field, we are
witnessing the growth of speech deepfake generation techniques, which solicit
the development of synthetic speech detection algorithms to counter possible
mischievous uses such as frauds or identity thefts. In this paper, we consider
three different feature sets proposed in the literature for the synthetic
speech detection task and present a model that fuses them, achieving overall
better performances with respect to the state-of-the-art solutions. The system
was tested on different scenarios and datasets to prove its robustness to
anti-forensic attacks and its generalization capabilities.Comment: Accepted at ECML-PKDD 2023 Workshop "Deep Learning and Multimedia
Forensics. Combating fake media and misinformation
Growth of sp-sp² nanostructures in a carbon plasma
The growth of sp and sp² nanostructures in a carbon plasma is simulated by tight-binding molecular dynamics. The simulations are arranged so as to mimic the cluster formation conditions typical of a pulsed microplasma cluster source which is used to grow nanostructured sp-sp² carbon films [L. Ravagnan et al., Phys. Rev. Lett. 98, 216103 (2007)]. The formation of linear, ring, and fullerenelike objects in the carbon plasma is found to proceed through a very long multistep process. Therefore, tight-binding simulations of unprecedented duration have been performed by exploiting the disconnected topology of the simulated carbon plasma which made it possible to implement a computationally efficient divide-and-diagonalize procedure. Present simulations prove that topologically different structures can be formed in experiments, depending on the plasma temperature and density. A thorough characterization of the observed structures as well as their evolution (caused both by thermal annealing and by cluster ripening) is provided.Yasutaka Yamaguchi, Luciano Colombo, Paolo Piseri, Luca Ravagnan, and Paolo Milani. Phys. Rev. B 76, 134119, 2007. Copyright 2007 by the American Physical Society
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