Improvement of interation in and properties of PMMA-MWNT nanocomposites through microwave assisted acid treatment of MWNT

Soluble derivatives of multi-walled carbon nanotubes (MWNT) embedded in a poly(methylmethacrylate) (PMMA) matrix forming thick, homogeneous and transparent nanocomposites, were prepared and characterized. A new photo-assisted method using microwaves, to purify the MWNTs from amorphous carbon and synthesis catalyst clusters, was tested in a sulphonitric mix. This method shortened the processing time compared to other methods. Pristine and functionalized MWNTs were introduced into the MMA, then in situ photo-polymerized. Transmission electron microscopy (TEM) and X-ray diffractometry (XRD), as well as Fourier-transform infrared (FTIR), Raman and nuclear magnetic resonance (NMR) spectroscopy were used to monitor the effects of the treatment on the different components. The thermal properties of the composites were determined through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The short, microwave treated and polyethylene glycol (PEG) functionalized MWNTs showed the best dispersion in and interaction with PMMA, and had the most significant influence on the thermal properties of this polymer

Chemogenic versus biogenic synthesis of Selenium nanoparticles: a structural characterization

Among the plethora of available metal- and metalloid-based nanomaterials (NMs), selenium nanostructures (SeNSs) are one of the most interesting from an applicative perspective due to their intermediate properties between metals and non-metals, as well as their high biocompatibility. In this regard, the capability of microorganisms to biotransform toxic Se-oxyanions – i.e., selenite (SeO32-) and selenate (SeO42-) – into their less bioavailable elemental forms [Se(0)], mostly generating Se nanoparticles (SeNPs), represents as a useful and green alternative over chemogenic synthesis allowing to obtain highly thermodynamically stable NMs. However, their structural characterization, in terms of biomolecules and interactions stabilizing the biogenic colloidal solution, is still a black hole in the microbial nanotechnology field, impairing the exploitation of biogenic SeNP full potential. Here, a parallel characterization between biogenic and chemogenic SeNPs was carried out through Fourier Transform Infrared spectroscopy in Attenuated Total Reflectance (ATR-FTIR) mode, Nuclear Magnetic Resonance (NMR) spectroscopy, and Density Functional Theory (DFT) calculations, to better understand which functional groups, hence biomolecules, contribute the most to the stabilization of biogenic SeNPs

Stradivari's Varnish Revisited: Feature Improvements Using Chemical Modification

The most widespread varnish formulations used by master violin-makers of the "Italian Golden Age", including Antonio Stradivari, were based on mixtures of siccative oils (e.g., linseed oil) and natural resins (e.g., colophony). Similar formulations are still used for the finish of contemporary instruments. Although most precious violins made by Stradivari and other Cremonese Masters are kept in museums, several instruments are still played and their finish may undergo deterioration due to contact with the players. Moreover, the decay of the traditional varnish may occur due to mechanical stress and natural aging caused by environmental agents (e.g., exposure to uncontrolled light, humidity, and temperature changes). The main aim of this research work is to investigate the possible improvement of varnish resistance to the decay induced by different aging processes. For this purpose, the traditional varnish (linseed oil/colophony 3:1 w/w) was recreated in the laboratory following an ancient recipe and then it was functionalized with a cross-linking agent (3-Glycidyloxypropyltrimethoxysilane, GLYMO). Plain and functionalized varnishes underwent artificial aging (UV light, temperature, and humidity variations), and their properties were comparatively studied using different techniques. All the results suggest that the functionalized varnish displays improved resistance to the aging process and particularly enhanced photostability and increased hardness (resistance to scratches)

Influence of the Ce :YAG amount on structure and optical properties of Ce :YAG-PMMA composites for white LED

Ce:YAG-poly(methyl methacrylate) (PMMA) composites were prepared by using a melt compounding method, adding several amounts of Ce:YAG in the range 0.1–5wt.%. The optical properties of the obtained composites and of the composites combined with a blue LED were measured to investigate the effect of the amount of Ce:YAG on the resulting emitted light in view of possible application in white LED manufacture. An increase in Ce:YAG amount caused an increase in the emission and a shift of 15 nm, influencing the white LED performance. The structure and morphology of the composites were studied. The results show that the interaction between the two components, observed by using solid state NMR experiments, are the responsible for the observed shift.The authors acknowledge the University of Palermo, FFR 2012–2013 –ATE 0594 and CORI201

The artificial retina processor for track reconstruction at the LHC crossing rate

We present results of an R&D study for a specialized processor capable of precisely reconstructing, in pixel detectors, hundreds of charged-particle tracks from high-energy collisions at 40 MHz rate. We apply a highly parallel pattern-recognition algorithm, inspired by studies of the processing of visual images by the brain as it happens in nature, and describe in detail an efficient hardware implementation in high-speed, high-bandwidth FPGA devices. This is the first detailed demonstration of reconstruction of offline-quality tracks at 40 MHz and makes the device suitable for processing Large Hadron Collider events at the full crossing frequency.Comment: 4th draft of WIT proceedings modified according to JINST referee's comments. 10 pages, 6 figures, 2 table

Cardiac involvement in systemic sclerosis: identification of high-risk patient profiles in different patterns of clinical presentation

Systemic sclerosis (SSc) is a chronic connective tissue disease characterized by widespread microvascular damage, dysregulation of fibroblasts with collagen overproduction and excessive fibrosis of the skin and internal organs, as well as complex immune system abnormalitie\u2026

A novel random counts estimation method for PET using a symmetrical delayed window technique and random single event acquisition

We have developed a novel logic scheme for the estimation of the random count distribution based on a dual symmetrical delayed window technique. The solution has been applied to a dual head PET case. We have also implemented a new method for noise variance reduction in the random count distribution

A flexible acquisition system for modular dual head Positron Emission Mammography

We have developed a dedicated scanner for Positron Emission Mammography, equipped with a new detection architecture that enhances its flexibility and reduces dead time. The scanner is going to use Luthetium based scintillators, which offer good detection efficiency, and a novel modular acquisition system, capable of sustaining the high scintillation rate and being less sensitive to background radiation. The final goal is the construction of an instrument able to provide an early diagnosis and to improve the effectiveness of follow-up studies for smaller tumours with respect to those studied with present clinical equipment (e.g. PET, SPECT o scintigraphy) so as to be able to visualize and characterize breast lesions with diameters < 5 mm

Measurement of the Lifetime Difference Between B_s Mass Eigenstates

We present measurements of the lifetimes and polarization amplitudes for B_s --> J/psi phi and B_d --> J/psi K*0 decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B_s system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203 +/- 15 B_s decays, we obtain tau_L = (1.05 +{0.16}/-{0.13} +/- 0.02) ps and tau_H = (2.07 +{0.58}/-{0.46} +/- 0.03) ps. Expressed in terms of the difference DeltaGamma_s and average Gamma_s, of the decay rates of the two eigenstates, the results are DeltaGamma_s/Gamma_s = (65 +{25}/-{33} +/- 1)%, and DeltaGamma_s = (0.47 +{0.19}/-{0.24} +/- 0.01) inverse ps.Comment: 8 pages, 3 figures, 2 tables; as published in Physical Review Letters on 16 March 2005; revisions are for length and typesetting only, no changes in results or conclusion