Potentiometric pH selective tips for scanning electrochemical microscopy (SECM) have been developed and used to image local pH changes in a variety of model chemical systems. Images of pH profiles around a platinum microelectrode during water reduction, a corroding disk of silver iodide in aqueous potassium cyanide, a disk of immobilized urease hydrolyzing urea, and a disk of immobilized yeast ...

A local magnetic characterization of disk-shaped MgB2 bulk samples synthesized by the Spark-Plasma-Sintering technique was carried out aimed at studying the material magnetic shielding properties. This growth technique allows one to produce samples in different shapes and sizes as required for shielding applications. The analysis employed a linear array of Hall probes mounted on a custom-design...

Introduction: The affinity of oxygen for both gaseous and solid phases makes it and its isotopes important tracers of redox conditions and isotopic reservoirs in the solar nebula. The oxygen fugacity (fO 2) recorded by chondritic meteorites ranges over several orders of magnitudes, from very high values needed to explain such minerals as ferrous olivine in ordinary and carbonaceous chondrites t...

K. T. Faber Department of Materials Science and Engineering, Northwestern University Evanston, IL 60208 There is experimental evidence that stress-induced microcracking near a macrocrack tip enhances thefraclUre toughness of brittle materials. In considering the interaction of the macrocrack with multiple microcracks using a discrete model, it is essential to use approximation methods in order ...

We model the X-rays reprocessed by an accretion disk in a fiducial low-mass X-ray binary system with a neutron star primary. An atmosphere, or the intermediate region between the optically thick disk and a Compton-temperature corona, is photoionized by the neutron star continuum. X-ray lines from the recombination of electrons with ions dominate the atmosphere emission and should be observable ...

Introduction: CO self-shielding is presently the leading hypothesis for explaining the CAI oxygen isotope mixing line [1]. Preliminary analyses of GENESIS solar wind samples show that the solar wind ions have ΔO ~ -20 ‰ [2], similar to the isotopically lightest CAIs. Barring non-mass-dependent fractionation during solar wind acceleration and ion passage through the GENESIS ion concentrator, the...

conclusions comprehensive protection programs with on-the-job training courses for staff members are strongly recommended, as well as, the provision of radiological shields and gonad shielding protocols in radiology departments to reduce the patient’s radiation dose during radiological examinations. materials and methods a retrospective, observational cross-sectional study on the application of...

Abstract We investigate the effect of conductive heating gas surrounding a geometrically thick accretion disk on growth black hole (BH) at high redshift. If BH is accreting super-Eddington rate, X-ray radiation from vicinity would be highly anisotropic due to self-shielding disk, and then radiative feedback medium suppressed in equatorial region, within which can continue. However, if this regi...

Aims. The chemistry, distribution and mass of the gas in the transitional disk around the 5 Myr old B9.5 V star HD 141569A are constrained. Methods. A quasi 2-dimensional (2D) chemistry code for photon dominated regions (PDR) is used to calculate the chemistry and gas temperatures in the disk. The calculations are performed for several gas distributions, PAH abundances and values of the total g...