A Novel Approach for an Integrated Straw tube-Microstrip Detector

We report on a novel concept of silicon microstrips and straw tubes detector, where integration is accomplished by a straw module with straws not subjected to mechanical tension in a Rohacell $^{\circledR}$ lattice and carbon fiber reinforced plastic shell. Results on mechanical and test beam performances are reported on as well.Comment: Accepted by Transactions on Nuclear Science (2005). 11 pages, 9 figures, uses lnfprep.st

Survey on Adsorption of Low Molecular Weight Compounds in Cu-BTC Metal–Organic Framework: Experimental Results and Thermodynamic Modeling

This contribution aims at providing a critical overview of experimental results for the sorption of low molecular weight compounds in the Cu-BTC Metal–Organic Framework (MOF) and of their interpretation using available and new, specifically developed, theoretical approaches. First, a literature review of experimental results for the sorption of gases and vapors is presented, with particular focus on the results obtained from vibrational spectroscopy techniques. Then, an overview of theoretical models available in the literature is presented starting from semiempirical theoretical approaches suitable to interpret the adsorption thermodynamics of gases and vapors in Cu-BTC. A more detailed description is provided of a recently proposed Lattice Fluid approach, the Rigid Adsorbent Lattice Fluid (RALF) model. In addition, to deal with the cases where specific self- and cross-interactions (e.g., H-bonding, Lewis acid/Lewis base interactions) play a role, a modification of the RALF model, i.e., the RALFHB model, is introduced here for the first time. An extension of both RALF and RALFHB is also presented to cope with the cases in which the heterogeneity of the rigid adsorbent displaying a different kind of adsorbent cages is of relevance, as it occurs for the adsorption of some low molecular weight substances in Cu-BTC MOF

Chemical Vapour Deposition Graphene–PMMA Nanolaminates for Flexible Gas Barrier

Successful ways of fully exploiting the excellent structural and multifunctional performance of graphene and related materials are of great scientific and technological interest. New opportunities are provided by the fabrication of a novel class of nanocomposites with a nanolaminate architecture. In this work, by using the iterative lift-off/float-on process combined with wet depositions, we incorporated cm-size graphene monolayers produced via Chemical Vapour Deposition into a poly (methyl methacrylate) (PMMA) matrix with a controlled, alternate-layered structure. The produced nanolaminate shows a significant improvement in mechanical properties, with enhanced stiffness, strength and toughness, with the addition of only 0.06 vol% of graphene. Furthermore, oxygen and carbon dioxide permeability measurements performed at different relative humidity levels, reveal that the addition of graphene leads to significant reduction of permeability, compared to neat PMMA. Overall, we demonstrate that the produced graphene–PMMA nanolaminate surpasses, in terms of gas barrier properties, the traditional discontinuous graphene–particle composites with a similar filler content. Moreover, we found that the gas permeability through the nanocomposites departs from a monotonic decrease as a function of relative humidity, which is instead evident in the case of the pure PMMA nanolaminate. This work suggests the possible use of Chemical Vapour Deposition graphene–polymer nanolaminates as a flexible gas barrier, thus enlarging the spectrum of applications for this novel material

Antioxidant Supplementation Hinders the Role of Exercise Training as a Natural Activator of SIRT1

Exercise training (ET) is a natural activator of silent mating type information regulation 2 homolog 1 (SIRT1), a stress-sensor able to increase the endogenous antioxidant system. SIRT1 activators include polyphenols and vitamins, the antioxidant properties of which are well-known. Antioxidant supplements are used to improve athletic performance. However, they might blunt ET-related benefits. Middle-distance runners (MDR) taking (MDR-S) or not taking antioxidant supplements (MDR-NoS) were compared with each other and with sedentary subjects (CTR) to evaluate the ET effects on SIRT1 levels and oxidative stress, and to investigate whether an exogenous source of antioxidants could interfere with such effects. Thirty-two MDR and 14 CTR were enrolled. MDR-S took 240 mg vitamin C and 15 mg vitamin E together with mineral salts. SIRT1 mRNA and activity were measured in PBMCs. Total oxidative status (TOS) and total antioxidant capacity (TEAC) were determined in plasma. MDR showed higher levels of SIRT1 mRNA (p = 0.0387) and activity (p = 0.0055) than did CTR. MDR-NoS also showed higher levels than did MDR-S without reaching statistical significance. SIRT1 activity was higher (p = 0.0012) in MDR-NoS (1909 ± 626) than in MDR-S (1276 ± 474). TOS did not differ among the groups, while MDR showed higher TEAC levels than did CTR (2866 ± 581 vs. 2082 ± 560, p = 0.0001) as did MDR-S (2784 ± 643) and MDR-NoS (2919 ± 551) (MDR-S vs. CTR, p = 0.0007 and MDR-NoS vs. CTR, p = 0.003). TEAC (β = 0.4488356, 95% CI 0.2074645 0.6902067; p < 0.0001) and the MDR-NoS group (β = 744.6433, 95% CI 169.9954 1319.291; p= 0.012) predicted SIRT1 activity levels. Antioxidant supplementation seems to hinder the role of ET as a natural activator of SIRT1

Micrometric Position Monitoring Using Fiber Bragg Grating Sensors in Silicon Detectors

We show R&D results including long term stability, resolution, radiation hardness and characterization of Fiber Grating sensors used to monitor structure deformation, repositioning and surveying of silicon detector in High Energy Physics.Comment: Presented by S.Bianco at ICATPP05, Villa Olmo (Como) Italy, November 2005. 5 pages, 6 figures, uses lnfprep.st

Two- and Three-Dimensional Reconstruction and Analysis of the Straw Tubes Tomography in the Btev Experiment

A check of the eccentricity of the aluminised kapton straw tubes used in the BTeV experiment is accomplished using X-ray tomography of the section of tubes modules. 2 and 3-dimensional images of the single tubes and of the modules are reconstructed and analysed. Preliminary results show that a precision better than 40 $\mu$m can be reached on the measurement of the straw radii.Comment: Presented by F.Massa at ICATPP05, Villa Olmo (Como) Italy, November 2005. 4 pages, 8 figures, uses lnfprep.st

Activity coefficients at infinite dilution via a perturbation method of NRHB model

Activity coefficients of solutes at infinite dilution play a central role in molecular thermodynamics of phase equilibria, solvation, solubility and related properties. Numerous equation-of-state models highly appropriate for concentrated systems have been developed in the open literature. Quite often, however, their equations for the chemical potential or the activity coefficient are not analytical and recursive numerical methods are needed for their use. This is the case for the versatile and widely used Non-Randomness with Hydrogen-Bonding equation of state model and, in the present work, a straightforward perturbation method is used for the derivation of analytical expressions for the chemical potential or the activity coefficient of solute at infinite dilution. The derivations are validated and compared with the full numerical calculations as well as with relevant experimental data. It is shown that calculations with the approximate analytical equations are essentially identical with the full numerical ones. These derivations are of a general character and may be used in a variety of other analogous thermodynamic models

Solubility and diffusivity of low molecular weight compounds in semi-crystalline poly-(2,6-dimethyl-1,4-phenylene)oxide: The role of the crystalline phase

The transport properties , i.e. sorption isotherm and diffusivity, of propane and methanol in totally amorphous polyphenyleneoxide (aPPO) and semi-crystalline nanoporous PPO (bPPO), obtained by treating with benzene vapours the amorphous sample, have been evaluated gravimetrically. In contrast to what is commonly observed in semi-crystalline polymers, bPPO shows a larger sorption capacity and faster sorption kinetics as compared to the totally amorphous sample: this behaviour, observed also in the case of sorption of liquid methanol, is discussed in terms of the morphology of the samples attributing the observed peculiarities prevalently to the non negligible sorption capacity of nanoporous crystalline domain. The nanoporous nature of crystalline phase has been confirmed also by DSC analysis, which points out that the crystalline domain displays a very low melting temperature. Sorption experiments indicate that semi-crystalline PPO is a promising candidate for use as membrane material in gas separation processes, in view of the remarkably high values of solubility and diffusivity. Finally, in the case of propane, the sorption experiments were repeated at different temperatures, to quantify the sorption enthalpy aPPO and bPPO