Measurements of the Rate Capability of Various Resistive Plate Chambers

Resistive Plate Chambers (RPCs) exhibit a significant loss of efficiency for the detection of particles, when subjected to high particle fluxes. This rate limitation is related to the usually high resistivity of the resistive plates used in their construction. This paper reports on measurements of the performance of three different glass RPC designs featuring a different total resistance of the resistive plates. The measurements were performed with 120 GeV protons at varying beam intensitie

Deducing the pathogenic contribution of recessive ABCA4 alleles in an outbred population

Accurate prediction of the pathogenic effects of specific genotypes is important for the design and execution of clinical trials as well as for meaningful counseling of individual patients. However, for many autosomal recessive diseases, it can be difficult to deduce the relative pathogenic contribution of individual alleles because relatively few affected individuals share the same two disease-causing variations. In this study, we used multiple regression analysis to estimate the pathogenicity of specific alleles of ABCA4 in patients with retinal phenotypes ranging from Stargardt disease to retinitis pigmentosa. This analysis revealed quantitative allelic effects on two aspects of the visual phenotype, visual acuity (P < 10−3) and visual field (P < 10−7). Discordance between visual acuity and visual field in individual patients suggests the existence of at least two non-ABCA4 modifying factors. The findings of this study will facilitate the discovery of factors that modify ABCA4 disease and will also aid in the optimal selection of subjects for clinical trials of new therapies

Challenges in Ceramic Science: A Report from the Workshop on Emerging Research Areas in Ceramic Science

In March 2012, a group of researchers met to discuss emerging topics in ceramic science and to identify grand challenges in the field. By the end of the workshop, the group reached a consensus on eight challenges for the future:—understanding rare events in ceramic microstructures, understanding the phase-like behavior of interfaces, predicting and controlling heterogeneous microstructures with unprecedented functionalities, controlling the properties of oxide electronics, understanding defects in the vicinity of interfaces, controlling ceramics far from equilibrium, accelerating the development of new ceramic materials, and harnessing order within disorder in glasses. This paper reports the outcomes of the workshop and provides descriptions of these challenges

The Intersection of Interfacial Forces and Electrochemical Reactions

We review recent developments in experimental techniques that simultaneously combine measurements of the interaction forces or energies between two extended surfaces immersed in electrolyte solutions—primarily aqueous—with simultaneous monitoring of their (electro)chemical reactions and controlling the electrochemical surface potential of at least one of the surfaces. Combination of these complementary techniques allows for simultaneous real time monitoring of angstrom level changes in surface thickness and roughness, surface–surface interaction energies, and charge and mass transferred via electrochemical reactions, dissolution, and adsorption, and/or charging of electric double layers. These techniques employ the surface forces apparatus (SFA) combined with various “electrochemical attachments” for in situ measurements of various physical and (electro)chemical properties (e.g., cyclic voltammetry), optical imaging, and electric potentials and currents generated naturally during an interaction, as well as when electric fields (potential differences) are applied between the surfaces and/or solution—in some cases allowing for the chemical reaction equation to be unambiguously determined. We discuss how the physical interactions between two different surfaces when brought close to each other (<10 nm) can affect their chemistry, and suggest further extensions of these techniques to biological systems and simultaneous in situ spectroscopic measurements for chemical analysis

Tellurium Vanadate Glasses: V4+colorimetric Measure and Its Effect on Conductivity

This research comes as part of a broader resurgence of study on the electrical conductivity of glasses—and the mechanism for electronic motion in the amorphous network—spurred by interest in using glasses as matrices for solid-state batteries, taking advantage of the glasses’ tailorable conductivity, chemical durability, and mechanical strength. The work presented in this study regards the preparation and characterization of some binary glasses belonging to the TeO2–V2O5 system. In particular, we focused on the glasses’ electrical conductivity at room temperature and at higher temperatures as a function of the V4+ ion content in the glass structure. The amount of V4+ in the glass was determined by a colorimetric method. Moreover, density and thermal properties (Tg, Cp) were measured, and scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements were performed as well

A Si-29 MAS NMR study of silicate glasses with a high lithium content

A series of lithium silicate glasses approaching the orthosilicate composition (66.7 mol% Li2O) were prepared and their Si-29 magic angle spinning nuclear magnetic resonance (NMR) recorded; this significantly extends the compositional range of glasses studied by this technique. The results indicate that the lever (binary) rule is approximately followed, though with considerable dissociation of the stoichiometric groups into silicate units with lesser and greater numbers of non-bridging oxygens according to the relation 2Q(n)-> Q(n+1)+Q(n-1). The NMR results were compared with the Raman study of Umesaki et al (1988 J. Non-Cryst. Solids 106 77-80) on the same system. Volumes per mol silica, determined from the experimental densities, were also used to test the structural results from the present NMR observations

Challenges In Ceramic Science: A Report From The Workshop On Emerging Research Areas In Ceramic Science

In March 2012, a group of researchers met to discuss emerging topics in ceramic science and to identify grand challenges in the field. By the end of the workshop, the group reached a consensus on eight challenges for the future:-understanding rare events in ceramic microstructures, understanding the phase-like behavior of interfaces, predicting and controlling heterogeneous microstructures with unprecedented functionalities, controlling the properties of oxide electronics, understanding defects in the vicinity of interfaces, controlling ceramics far from equilibrium, accelerating the development of new ceramic materials, and harnessing order within disorder in glasses. This paper reports the outcomes of the workshop and provides descriptions of these challenges. © 2012 The American Ceramic Society

XAFS study on the local order of Pb in PbO borate glasses

An XAFS study on several samples of borate glasses with increasing PbO concentrations was performed in order to detect a possible clustering of Pb atoms or PbO structures. Samples with concentrations from 28.6 up to 75% of PbO were examined at the L-3 edge of Pb. Analysis of data was carried out by experimental comparison with low temperature crystalline references and with the results of theoretical evaluation of amplitude and phases of possible Pb-Pb and Pb-O structures. It was observed that, even at the highest concentration, metallic Pb segregation is incompatible with the obtained XAFS spectra. The most probable structure of Pb neighbours is a tetrahedral replica of the PbO structure (litharge or red PbO). This order weakly extends also to second neighbours, except for the least concentrated sample in which only a distorted first PbO shell was reproduced

Synthesis and characterization of (68-x) CuO – xV<inf>2</inf>O<inf>5</inf> – 32TeO<inf>2</inf> (x = 0–68 mol%) and (35-x) CuO – xV<inf>2</inf>O<inf>5</inf> – 65TeO<inf>2</inf> (x = 0–35 mol%) glasses: Conduction mechanism, structure and EPR study

In this work, two series of glasses, i.e. (68-x) CuO – xV2O5 – 32TeO2 (x = 0–68 mol%, Te32 series) and (35-x) CuO – xV2O5 – 65TeO2 (x = 0–35 mol%, Te65 series), were synthesized by the melt-quenching method and subjected to physical, thermal and electrical characterization. Their vitreous nature was confirmed by X-Ray diffraction and differential scanning calorimetry, while their structural units were determined by Raman spectroscopy. CuO substitution by V2O5 led to a decrease in density and glass-transition temperature, together with a conductivity increase. Conduction mechanism was interpreted as mainly due to small polaron hopping from the lower (V4+) to the higher (V5+) vanadium valence states. Te32 glasses, possessing the highest electronic conductivities (ranging from 2 E−4 to 5 E−7 Ω−1 cm−1), were investigated by the Electron Paramagnetic Resonance technique, in order to more deeply analyze their structure-conductivity correlation. Particularly, the observed signals were determined to consist in a superposition of a first line due to paramagnetic Cu2+ ions and a second line due to exchange-coupled CuO clusters. Differences in the spectra were determined between samples with higher (i.e. 20-30 mol%) Cu2+ concentrations and samples with lower Cu2+ concentrations, suggesting they are located in different local environments. Finally, it was found that the Cu2+ ions are not involved in the process of electron transfer