Capillarity-driven dynamics of water–alcohol mixtures in nanofluidic channels

We investigated the spontaneous capillarity-driven filling of nanofluidic channels with a thickness of 6 and 16 nm using mixtures of ethanol and water of variable composition. To improve the visibility of the fluid, we embedded metal mirrors into the top and bottom walls of the channels that act as a Fabry–Pérot interferometer. The motion of propagating liquid–air menisci was monitored for various concentrations in transmission with an optical microscope. In spite of the visible effects of surface roughness and different affinity of water and ethanol to the channel walls, the dynamics followed the classical t 1/2—dependence according to Lucas and Washburn. While the prefactor of this algebraic relation falls short of the expectations based on bulk properties by 10–30%, the relative variation between mixtures of different composition follows the expectations based on the bulk surface tension and viscosity, implying that—despite the small width of the channels and the large surface-to-volume ratio—specific adsorption or chemical selectivity effects are not relevant. We briefly discuss the impact of surface roughness on our experimental results

The phenomenology of electric dipole moments in models of scalar leptoquarks

We study the phenomenology of electric dipole moments (EDMs) induced in various scalar leptoquark models. We consider generic leptoquark couplings to quarks and leptons and match to Standard Model effective field theory. After evolving the resulting operators to low energies, we connect to EDM experiments by using up-to-date hadronic, nuclear, and atomic matrix elements. We show that current experimental limits set strong constraints on the possible CP-violating phases in leptoquark models. Depending on the quarks and leptons involved in the interaction, the existing searches for EDMs of leptons, nucleons, atoms, and molecules all play a role in constraining the CP-violating couplings. We discuss the impact of hadronic and nuclear uncertainties as well as the sensitivities that can be achieved with future EDM experiments. Finally, we study the impact of EDM constraints on a specific leptoquark model that can explain the recent $B$-physics anomalies.Comment: Published versio

Titanium and water-rich metamorphic olivine in high-pressure serpentinites from the Voltri Massif (Ligurian Alps, Italy): evidence for deep subduction of high-field strength and fluid-mobile elements

Titanium- and water-rich metamorphic olivine (Fo 86-88) is reported from partially dehydrated serpentinites from the Voltri complex, Ligurian Alps. The rocks are composed of mostly antigorite and olivine in addition to magnetite, chlorite, clinopyroxene and Ti-clinohumite. In situ secondary ion mass spectrometry (SIMS) data show that metamorphic olivine has very high and strongly correlated H2O (up to 0.7 wt%) and TiO2 contents (up to 0.85 wt%). Ti-rich olivine shows colourless to yellow pleochroism. Olivine associated with Ti-clinohumite contains low Ti, suggesting that Ti-rich olivine is not the breakdown product of Ti-clinohumite. Fourier transform infrared spectroscopy (FTIR) absorption spectra show peaks of serpentine, Ti-clinohumite and OH-related Si vacancies. Combining FTIR and SIMS data, we suggest the presence of clustered planar defects or nanoscale exsolutions of Ti-clinohumite in olivine. These defects or exsolutions contain more H2O (x similar to 0.1 in the formula 4Mg(2)SiO(4)center dot(1-x)Mg(OH, F)(2)center dot xTiO(2)) than Ti-clinohumite in the sample matrix (x = 0.34-0.46). In addition to TiO2 and H2O, secondary olivine contains significant Li (2-60 ppm), B (10-20 ppm), F (10-130 ppm) and Zr (0.9-2.1 ppm). It is enriched in B-11 (delta B-11 = +17 to +23 parts per thousand). Our data indicate that secondary olivine may play a significant role in transporting water, high-field strength and fluid-mobile elements into the deeper mantle as well as introduce significant B isotope anomalies. Release of hydrogen from H2O-rich olivine subducted into the deep mantle may result in strongly reduced mantle domains.OAIID:oai:osos.snu.ac.kr:snu2014-01/102/0000043439/1SEQ:1PERF_CD:SNU2014-01EVAL_ITEM_CD:102USER_ID:0000043439ADJUST_YN:YEMP_ID:A076886DEPT_CD:3345CITE_RATE:3.476FILENAME:de hoog et al-14-cmp-titanium- and water-ric.pdfDEPT_NM:지구환경과학부SCOPUS_YN:NCONFIRM:

Giant nonlinear response of superconducting single crystal niobium in a sweeping magnetic field

Giant enhancement of the nonlinear response of a single crystal of Nb placed in a sweeping magnetic field has been experimentally observed. The rectified signal from Nb ($Tc=9.15$ K) has been measured by means of an inductive method as a function of temperature, dc field, dc field sweep rate, and the amplitude of ac field. The Nb sample was excited by an amplitude modulated ac field. Under a stationary regime, the rectified signal appears only for magnetic fields ($H_0$) in the range $H_{c2}<H_0<H_{c3}$ . However, when the dc field was swept slowly, the rectified signal appears at $H_0>H_{c1}$. This experiment shows that the amplitude of the rectified signal is two orders of magnitude larger than the amplitude of the signal seen under stationary field conditions. Moreover, the amplitude of the rectified signal is a power function of the sweep rate, with the power exponent close to 1.Comment: 3 pages, 3 figures, presented to EUCAS 200

Towards diagnosis of rotator cuff tears in 3-D MRI using 3-D convolutional neural networks

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Tracking Brazilian Exchange Rate Volatility

This paper examines the relation between dollar-real exchange rate volatility implied in option prices and subsequent realized volatility. It investigates whether implied volatilities contain information about volatility over the remaining life of the option which is not present in past returns. Using GMM estimation consistent with telescoping observations evidence suggests that implied volatilities give superior forecasts of realized volatility if compared to GARCH(p,q), and Moving Average predictors, and that econometric models forecasts do not provide significant incremental information to that contained in implied volatilities.implied volatility, telescoping observations, GMM

Study of electrical properties of 2- and 3-dimensional carbon nanotubes networks

Des réseaux bi- et tridimensionnels de nanotubes de carbone (2D- et 3D-CNTNs) ont été préparés sur substrat de silice amorphe et dans une matrice silice. Les aptitudes de plusieurs types de CNTs (mono-, double- et multi-parois : SWCNTs, DWCNTs et MWCNTs) à former un réseau percolant ont été comparées par mesure de la conductivité électrique (EC) de suspensions dynamiques de ces CNTs dans le chloroforme. Les suspensions de SWCNTs présentent une EC normalisée maximale (3.08 S.cm2/g) d'où leur choix pour les 2D-CNTNs tandis que les suspensions de DWCNTs ont le plus faible seuil de percolation (0.002-0.06 vol.%) d'où leur choix pour les 3D CNTNs. Pour les 2D-CNTNs, des suspensions aqueuses de SWCNTs (avec surfactant et sonication par sonde (PS)) ont été déposées par trempage, filtration, spray et dépôt électrophorétique. La plupart des 2D-CNTNs forment un réseau percolant dont EC obéit à la loi de puissance (exposant d'environ 1,29). Leurs conductance de surface et transparence dans l'UV permettent leur utilisation dans les écrans d'affichage, les écrans tactiles, les tubes cathodiques et la dissipation des charges électrostatiques. Les CNTNs les plus lisses sont intéressants pour les cellules solaires. Les 3D-CNTNs (nanocomposites) ont été préparés par sol-gel avec des DWCNTs modérément fonctionnalisés (avec/sans séchage) dispersés par PS, puis densifiés par "spark-plasma sintering". La voie sèche conduit au plus faible seuil de percolation (0,35 vol.% DWCNT) alors que le matériau le plus conducteur de la voie humide présente une EC de 1,56 S/cm (6,43 vol.% DWCNT). Les EC sont suffisantes pour l'évacuation des charges électrostatiques ou pour servir d'éléments chauffants.Two and three dimensional carbon nanotube networks (2D- and 3D-CNTNs) were prepared over silica glass substrate and in silica matrix, respectively. The aptitudes of various CNTs (single-, double- and multi-walled CNTs: SWCNTs, DWCNTs and MWCNTs, respectively) to form percolating CNTNs were compared by measurement of their electrical conductivity (EC) in dynamic suspensions in chloroform. The SWCNTs suspensions show the highest maximum normalized EC (3.08 S.cm2/g) while the DWCNTs ones have the lowest percolation thresholds (0.002-0.06 vol.%). This led to choose SWCNTs for 2D-CNTNs and DWCNTs for 3D ones. To produce 2D-CNTNs, SWCNTs aqueous suspensions (prepared with surfactant and probe sonication, PS) were deposited over the substrates through: dip-coating (DC), filtration (FM), spray-coating (SC) and electrophoretic deposition (ED). Most of the 2D-CNTNs formed a percolating CNTN whose EC follow the power law (exponent ~1.29). Their surface conductance and UV transparency allow their use in displays, touch screens, shielding in cathode tubes and electrostatic dissipation. The smoothest CNTNs obtained by DC and ED are also interesting for solar cells. The 3D-CNTNs were prepared by sol-gel route using mildly functionalized DWCNTs (with/without dry step) dispersed with PS. The nanocomposites were fully densified by spark-plasma sintering. The "Dry" route allowed the lowest percolation threshold (0.35 vol.% DWCNT), while the more conductive material from "Wet" route shows EC of 1.56 S/cm (6.43 vol.% DWCNTs). Besides the dispersion of CNTs could be improved, the achieved EC of these nanocomposites is high enough for their use in anti-electrostatic or heating applications

Duality and canonical extensions for stably compact spaces

We construct a canonical extension for strong proximity lattices in order to give an algebraic, point-free description of a finitary duality for stably compact spaces. In this setting not only morphisms, but also objects may have distinct pi- and sigma-extensions.Comment: 29 pages, 1 figur

Electrical conductive double-walled carbon nanotubes � Silica glass nanocomposites prepared by the sol�gel process and spark plasma sintering

The electrical conductivity of suspensions in liquid of several kinds of carbon nanotubes (CNTs) is measured. Raw and soft-functionalized double-walled carbon nanotubes (DWCNTs) appear to be the most promising for achieving a low electrical percolation threshold. A 0.35 vol.% DWCNTs�SiO2 nanocomposite is prepared by the sol�gel process and densified by spark plasma sintering. The obtained material presents a fairly good dispersion of DWCNTs and its electrical conductivity (104 S cm1) is six orders of magnitude higher than that previously reported for 1 vol.% multi-walled CNTs�SiO2