High frequency titrations involving chelation with ethylenediaminetetraacetic acid: Determination of uranyl ion

It has been shown that for the pH range of 3.5 to 4.0, ethylenediaminetetraacetic acid reacts with uranyl ion to form a stable salt. The reacting ratio was found to be 2 : 1 (metal to addendum) which is in contrast to the usual reacting ratio of 1 : 1 obtained with ethylenediaminetetraacetic acid and other heavy metals. The chelate obtained with uranyl ion is probably a pseudo salt.A high frequency titration employing tri-sodium ethylenediaminetetraacetate is suggested for the determination of uranyl ion.     

The effect of furniture and boundary conditions on the sound attenuation in a landscaped office: Part 1

Attenuation curves calculated using an image model are compared with measurements taken in an office with a number of different boundary conditions applied. The agreement is good in the absence of screens. Measurements were also taken with different screen layouts, which did not interrupt the line of sight to the source. A method is proposed by which the theoretical predictions can be improved in the presence of screens.     

Spectrophotometric determination of traces of formaldehyde

Summary A comparative study of various colorimetric methods for determining and detecting traces of formaldehyde has been made. Chromotropic acid and 2,7-duiydroxynaphthalene were found to be the best reagents and were subjected to a thorough study. Precise and accurate methods for determining formaldehyde using either chromotropic acid or 2,7-dihydroxynaphthalene are described. The color system produced by following the standard procedure obeys Beer's law. Using chromotropic acid 0.05 g to 2.0 g of formaldehyde per ml can be determined quite accurately. Acrolein seems to be the only seriously interfering substance, and its interference can be much diminished by slightly modifying the standard procedure. The reagent solutions are perfectly stable.     

Kinetische Herleitung verallgemeinerter Nernst-Planck-Gleichungen. IV.) Korrelationen im quasihomogenen System

Kinetic Derivation of Generalized Nernst-Planck-Equations. IV. Correlations in a Quasi-Homogeneous System This paper shows the decoupling for the pair-correlation-equations for ions in an electrolyte solution from the one-particle-equations (generalized Nernst-Planck-equations). The consequence of the decoupling is the fact, that one can solve the pair-correlation-equations independent of the one-particle-equations: their solutions, the pair-correlation-functions, are functionals of the one-particle-functions.     

Temperature and magnetic-field-enhanced hall slope of a dilute 2D hole system in the ballistic regime

We report the temperature (T) and perpendicular magnetic-field (B) dependence of the Hall resistivity rho(xy)(B) of dilute metallic 2D holes in GaAs over a broad range of temperature (0.02-1.25 K). The low B Hall coefficient, R(H), is found to be enhanced when T decreases. Strong magnetic fields further enhance the slope of rho(xy)(B) at all temperatures studied. Coulomb interaction corrections of a Fermi liquid (FL) in the ballistic regime can not explain the enhancement of rho(xy) which occurs in the same regime as the anomalous metallic longitudinal conductivity. In particular, although the metallic conductivity in 2D systems has been attributed to electron interactions in a FL, these same interactions should reduce, not enhance, the slope of rho(xy)(B) as T decreases and/or B increases.     

Evidence for two different solid phases of two-dimensional electrons in high magnetic fields

We have observed two different rf resonances in the frequency dependent real diagonal conductivity of very high quality two-dimensional electron systems in the high magnetic field insulating phase and interpret them as coming from two different pinned electron solid phases (labeled as "A" and "B"). The "A" resonance is observable for Landau level filling nu<2/9 [reentrant around the nu=1/5 fractional quantum Hall effect (FQHE)] and then crosses over to the different "B" resonance which dominates at sufficiently low nu. Moreover, the "A" resonance is found to show dispersion with respect to the size of the transmission line, indicating that the "A" phase has a large correlation length. We suggest that quantum correlations such as those responsible for FQHE may play an important role in giving rise to such different solids.     

Application of rapid, electrochemical Flash Titration to total acidity and alkalinity determinations in buffers, foods, and beverages

A new technique (Flash Titration) for the determination of total acidity and total alkalinity was applied to food and beverage analysis. Requiring no liquid titrants, Flash Titration is a technique made possible through microfabrication of electrochemical components on a silicon chip. Acidic or basic titrant was generated electrochemically at a noble-metal electrode that intimately surrounded an ion-selective, field-effect transistor pH sensor. As acid or base was generated through electrolysis, sample alkalinity or acidity, respectively, was neutralized in the immediate vicinity of the electrode. Through diffusion, a zone comprising a gradient of partially to totally neutralized sample expanded from the generating electrode into the volume element sensed by the nearby pH sensor. An analysis of the pH signal versus time revealed an end point inflection at an elapsed time related to the total alkalinity or acidity of the sample. End point times were typically a few seconds. In this paper, Flash Titration was applied to the analysis of a variety of samples, including juices, soft drinks, wines, and food products. The differences between the results obtained by the Flash Titration method and a commonly used conventional volumetric method were less than 2% in most food products tested. Analysis costs were reduced both through time saving and reduction or elimination of hazardous liquid titrant disposal, by the use of the Flash Titration method.