A spectral and polarographic study of the acid--base and complexing behaviour of bromazepam.

A method for the microdetermination of periodate in the presence of iodate is presented. It is based on reduction of periodate to iodate by leucothionine generated in situ by photochemical reaction between EDTA and blue thionine. Biamperometric curves are used for evaluation, representing reduction time for the periodate versus the current generated in the oxidation of the T_red in excess after the end-point. A polarographic study of the process is presented. An applied potential of 100 mV is suitable for the biamperometric measurements with Pt—Pt electrodes. The method is applicable for 0.4–45 ppm periodate. Iodate does not interfere up to IO^-₃ : IO^-₄ ratios of 100:1.     

An investigation of polyphenyl-onium bases and other materials for phosphate ion-selective electrodes

Precipitate-type electrodes (benzidine sulfate or phosphate and hexammino-cobalt(III) nitrate in silicone rubber), and liquid ion-exchanger electrodes based on quaternary ammonium and phosphonium and triphenyltin salts were tested for the assay of phosphate ions. Good sensitivity was achieved with the phosphonium and triphenyltin salts, but both lacked sufficient selectivity for routine-assays.     

The use of amperometric oxygen electrodes for measurements of enzyme reactions

Amperometric oxygen electrodes are useful transducers for enzymatic analyses. One must, however, account for contributions from oxygen incorporation or depletion caused by sample introduction, stirring and diffusion, or non-enzymatic reactions, as well as for instrumental response time. Examples of various characteristics of these contributions are shown and discussed from a theoretical basis.     

Small polaron electron transport in reduced CeO2 single crystals

An investigation of the electrical properties of reduced ceria, CeO_2?x, carried out on single crystals, shows that CeO_2?x provides one of the clearest examples of hopping conduction and the small polaron mechanism. Included are conductivity and Seebeck coefficient measurements at constant x, obtained by sealing off the specimen chamber after reduction. The Seebeck coefficient is independent of temperature, suggesting that the number of carriers is constant. On the other hand, the mobility is activated, with activation energy E_h = 0.40 eV at small x and increasing to 0.52 eV at x = 0.25. The results for the mobility preexponential are consistent with the adiabatic theory of small polaron behavior. A puzzling feature of the Seebeck data as a function of x is that, for low x, the data fit the well-known Heikes formula, without a degeneracy factor of 2 for spin. Nevertheless, these data are interpreted to show that the proportion of mobile carriers decreases as x increases, presumably because of the presence of short-range ordered configurations which immobilize some carriers.     

Intra-elemental photoelectron line intensities and their significance to quantitative analysis

Intraelemental relative photoelectron line intensities for 20 pure elements obtained under ultrahigh vacuum (5·10^?9 torr) and high resolution with cleaned surfaces are presented. Theoretical and experimental aspects of relative photoelectron line intensities as well as other characteristics of significance to quantitative analysis are discussed. Experimental data are related to theoretical results and compared with other recent work.     

A computer program system for kinetic analysis of non-isothermal thermogravimetric data: I. Data acquisition and preparation for kinetic analysis

FORTRAN software is described which enables the generation of rate of weight change data (DTG) from percentage weight change measurements (TG), obtained under non-isothermal conditions. The program also transposes this information into the dimensionless extent and rate of reaction at unit temperature intervals by means of a cubic spline interpolation. A simple search routine identifies all DTG spikes in the thermogravimetric record, and the temperature and extent of reaction at which the rate attains its maximum value. This total information serves as input data for the kinetic analysis software to be discussed in part II of this communication. An example of the application of this program to the pyrolysis of bituminous coal is presented.     

Simultaneous representation of interval and interval-containment orders

We characterize the polysemic interval pairs—pairs of posets that admit simultaneous interval and interval-containment representations—and present algorithms to recoginze them and construct polysemic interval representations.This work, supported in part by NSF grant CCR-9300079, also appears in the author's doctoral thesis [9], written at the Johns Hopkins University under the supervision of Professors Edward R. Scheinerman and Michael T. Goodrich.     

Microwave spectrum and substitutional structure of CH2DF

Forty-two transitions of the microwave spectrum of CH₂DF have been observed in the region between 75 and 450 GHz. The measurement of both a-type and b-type transitions makes possible the analysis of the spectrum and the accurate calculation of the rotational constants (in MHz): = 119 675.0535 ± 0.074, = 24 043.4415 ± 0.072, ? = 22959.3732 °0.072, °j = 0.049371 ±0.00011, °_jk = 0.34268 ±0.0006, 2_k = 3,3774 ± 0.0035, δ _j = 0.002329 ± 0.000045, δ_k = 0.0687 ± 0.036. These constants, in combination with the results of earlier work on the symmetric speci r_s structure calculation based entirely on high-accuracy microwave data. The structural parameters are r_CH = 1.100 Å, r_CF = 1.383 Å, and ∠HCH = 110° 37'.     

Some observations on the interdependence of cyanide concentration and atomization efficiency in the nitrous oxide-acetylene flame

A relationship is derived between CN concentration and atomization efficiency in the C₂H₂-N₂O flame. The relationship is examined under various experimental conditions and β values are estimated for a number of elements. The possibility of complex vapour phase oxide formation by U is considered.