OPERA neutrino oscillation results

The OPERA experiment was designed to perform the first detection of νμ → ντ neutrino oscillations in a direct appearance mode. We present the analysis results of the 2008–2009 statistics corresponding to 4.88 × 1019 p.o.t. In this sample, one ντ candidate event has been observed in the τ → h channel. The statistical significance of this observation is estimated to be 95%

D0D^0 production rate measurement in neutrino interactions and a limit on muon neutrino to tau neutrino oscillations

The CHORUS experiment was designed to search for \nu_\mu---> \nu_\tau oscillations. Recently, Phase I analysis has been completed and no \tau candidate is found. The second phase of the CHORUS analysis was recently started with new scanning systems. The big improvements in the scanning system and methods allow the CHORUS experiment to study also charm physics with large statistics. In this work, D^0 production rate in neutrino charged-current interactions has been evaluated using 122 D^0 candidates found in 8028 located \nu_\mu charged-current interactions in the collaboration, as; \sigma(\nu_mu N--> D^0\mu^-X)/sigma(\nu_mu N--> \mu^-X)= 1.998 \pm 0.223%. The achived precision of the production rate exceeds that of the previous experiments

Tuning viscoelastic properties of supermolecular peptide gels via dynamic covalent crosslinking

Cataloged from PDF version of article.A dynamic covalent crosslinking approach is used to crosslink supramolecular peptide gels. This novel approach facilitates tuning viscoelastic properties of the gel and enhances mechanical stability (storage modulus exceeding 10(5) Pa) of the peptide gels

Indentation of a free beam resting on an elastic substrate with an internal lengthscale

The plane strain problem of a slender and weightless beam-plate loaded by a transversal point force in unilateral contact with a couple stress elastic foundation is investigated. The study aims to explore the consequences of the material internal lengthscale on the contact mechanics. In particular, compatibility between the beam and the foundation surface demands that both displacement and rotation match along the contact line. To this aim, couple tractions are exchanged besides the traditional contact pressure until separation between the beam and the foundation occurs. The problem is formulated making use of the Green's functions for a point force and a point couple acting atop of a couple stress elastic half-plane. A pair of coupled integral equations is thus derived, that governs the distribution of contact pressure and couple tractions, with one of them being immediately solved to provide an explicit relation between the two unknowns. In this sense, we retrieve the concept of a mechanically equivalent action, as it is the case of the Kirchhoff shear for plates. The remaining integral equation sets a cubic eigenvalue problem, whose linear term accounts for the microstructure. Its numerical solution is sought by expanding the equivalent contact pressure in series of Chebyshev polynomials vanishing at the contact region ends points, namely the lift-off points, and then applying a collocation strategy. The contact length, the distributions of contact pressure and couple tractions under the beam and the shearing force and bending moment along the beam are then obtained as a function of the material characteristic length. Results clearly indicate that accounting for the material internal lengthscale is mainly realized through exchange of the couple tractions, in the lack of which results much resemble those of the classical solution. Specifically, greater contact lengths and a stronger focusing effect about the loading point are encountered, which become very significant when the contact length approaches the internal lengthscale

Couple stress effects in a thin film bonded to a half-space

This study investigates the contact mechanics of a thin film laying on an elastic substrate within the context of couple-stress elasticity. It aims to introduce the effects of material internal length scale, which has proven an effective way of modeling structures at micro to nano-scales, allowing to capture their size dependent behavior. Specifically, stress analysis for a thin film bonded to a couple stress elastic half-space is considered under plane strain loading conditions by assuming that both shear stress and couple tractions are exchanged between the thin film and the substrate. The problem is converted to a singular integral equation, which is solved by expanding the shear stress tractions as a Chebyshev series. The results show that the introduction of couple tractions decreases the shear stress tractions and the axial load in the thin film. When the characteristic length is sufficiently small, but still finite, the results for classical elastic behavior are approached

Highly Transparent, Flexible, and Thermally Stable Superhydrophobic ORMOSIL Aerogel Thin Films

Cataloged from PDF version of article.We report preparation of highly transparent, flexible, and thermally stable superhydrophobic organically modified silica (ORMOSIL) aerogel thin films from colloidal dispersions at ambient conditions. The prepared dispersions are suitable for large area processing with ease of coating and be:ing directly applicable without requiring any pre- or post-treatment on a variety of surfaces including glass, wood, and plastics. ORMOSIL films exhibit and retain superhydrophobic behavior up to 500 degrees C and even on bent flexible substrates. The surface of the films can be converted from superhydrophobic (contact angle of 179.9 degrees) to superhydrophilic (contact angle of <5 degrees) by calcination at high temperatures. The wettability of the coatings can be changed by tuning the calcination temperature and duration. The prepared films also exhibit low refractive index and high porosity making them suitable as multifunctional coatings for many application fields including solar cells, flexible electronics, and lab on papers

Template free preparation of nanoporous organically modified silica thin films on flexible substrates

Cataloged from PDF version of article.We report the preparation and characterization of nanoporous organically modified silica (ormosil) thin films at room temperature and neutral pH conditions from homogeneous methyl silsesquioxane (MSQ) gels. Universally applicable and stable colloidal ormosil suspensions are prepared from the gels by sonication and coated to the substrates including glass, paper and plastics. The nanoporosity and thickness of the films can be tuned, which makes them suitable for certain applications including sensing, functional coatings, and low-dielectric materials. We demonstrate the antireflection property of the films on glass, cellulose acetate (CA) and polyetherimide (PEI) substrates. The films on CA and PEI retain their antireflection property after multiple bending cycles. Furthermore, films are intrinsically hydrophobic, over a wide pH range, with static contact angles up to 143° on paper and 123° on glass and CA. Producing nanoporous ormosil thin films on flexible substrates may expand their use in low cost electronic, optical devices and sensors, and lab-on-paper applications

Tenascin-C Mimetic Peptide Nanofibers Direct Stem Cell Differentiation to Osteogenic Lineage

Cataloged from PDF version of article.Extracellular matrix contains various signals for cell surface receptors that regulate cell fate through modulation of cellular activities such as proliferation and differentiation. Cues from extracellular matrix components can be used for development of new materials to control the stem cell fate. In this study, we achieved control of stem cell fate toward osteogenic commitment by using a single extracellular matrix element despite the contradictory effect of mechanical stiffness. For this purpose, we mimicked bone extracellular matrix by incorporating functional sequence of fibronectin type III domain from native tenascin-C on self-assembled peptide nanofibers. When rat mesenchymal stem cells (rMSCs) were cultured on these peptide nanofibers, alkaline phosphatase (ALP) activity and alizarin red staining indicated osteogenic differentiation even in the absence of osteogenic supplements. Moreover, expression levels of osteogenic marker genes were significantly enhanced revealed by quantitative real-time polymerase chain reaction (qRT-PCR), which showed the remarkable bioactive role of this nanofiber system on osteogenic differentiation. Overall, these results showed that tenascin-C mimetic peptides significantly enhanced the attachment, proliferation, and osteogenic differentiation of rMSCs even in the absence of any external bioactive factors and regardless of the suitable stiff mechanical properties normally required for osteogenic differentiation. Thus, these peptide nanofibers provide a promising new platform for bone regeneratio

Noncovalent funstionalization of mesoporous silica nanoparticles with amphiphilic peptides

Cataloged from PDF version of article.The surface of mesoporous silica nanoparticles (MSNs) has been modified for enhancing their cellular uptake, cell targeting, bioimaging, and controlled drug release. For this purpose, covalent anchorage on the silica surface was predominantly exploited with a wide range of bioactive molecules. Here, we describe a facile self-assembly method to prepare a hybrid peptide silica system composed of octyl-modified mesoporous silica nanoparticles (MSNs) and peptide amphiphiles (PAs). The hydrophobic organosilane surface of mesoporous silica was coated with amphiphilic peptide molecules. The peptide functionalized particles exhibited good cyto-compatibility with vascular smooth muscle and vascular endothelial cells. The peptide coating also improved the cellular uptake of particles up to 6.3 fold, which is promising for the development of highly efficient MSN based theranostic agents. © 2014 the Partner Organisations

Cooperative effect of heparan sulfate and laminin mimetic peptide nanofibers on the promotion of neurite outgrowth

Cataloged from PDF version of article.Extracellular matrix contains an abundant variety of signals that are received by cell surface receptors contributing to cell fate, via regulation of cellular activities such as proliferation, migration and differentiation. Cues from extracellular matrix can be used for the development of materials to direct cells into their desired fate. Neural extracellular matrix (ECM) is rich in axonal growth inducer proteins, and by mimicking these permissive elements in the cellular environment, neural differentiation as well as neurite outgrowth can be induced. In this paper, we used a synthetic peptide nanofiber system that can mimic not only the activity of laminin, an axonal growth-promoting constituent of the neural ECM, but also the activity of heparan sulfate proteoglycans in order to induce neuritogenesis. Heparan sulfate mimetic groups that were utilized in our system have an affinity to growth factors and induce the neuroregenerative effect of laminin mimetic peptide nanofibers. The self-assembled peptide nanofibers with heparan sulfate mimetic and laminin-derived epitopes significantly promoted neurite outgrowth by PC-12 cells. In addition, these scaffolds were even effective in the presence of chondroitin sulfate proteoglycans (CSPGs), which are the major inhibitory components of the central nervous system. In the presence of these nanofibers, cells could overcome CSPG inhibitory effect and extend neurites on peptide nanofiber scaffolds. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved