Data Treatment Procedures Research Articles

Quantitation of Auger and X-ray Photoelectron Spectroscopies

Surface analysis using electron spectroscopies is now a well-established and continuously expanding area. With appropriate data treatment procedures, both Auger electron spectroscopy (AES, not to be confused with atomic expression spectroscopy) and X-ray photoelectron spectroscopy (XPS or ESCA) can routinely supply reliable qualitative and semiquantitative characterization of the near-surface region (top 1-100 /Angstrom/) of most solids. Complex sample matrix and instrumental parameters make quantitation of surface electron spectroscopies a real challenge. Kenneth W. Nebesny, Brian L. Mashloff, and Neal R. Armstrong of the University of Arizona describe approaches that make it possible to obtain reliable compositional information.

X-ray diffraction analysis of the structure of MBBA solid phases

The nematic liquid crystal compound MBBA exhibits a large number of solid phases, e.g., on fast cooling a glassy state may be formed, four metastable phases are obtainable by annealing. Since the sample relaxes by increasing the annealing temperature, the structure of the phases becomes less and less symmetric. X-ray diffraction measurements were performed to characterize the phase structure of non-aligned samples using a position sensitive x-ray camera. A data treatment procedure was elaborated to derive quantitative features of the diffraction patterns. The solid smectic structure of the non-completely-ordered phases are characterized.

A new procedure for determination of electron temperatures and electron concentrations by Thomson scattering from analytical plasmas

A new data-treatment procedure allows for more accurate determination of electron temperatures and electron concentrations in analytical plasmas. A Thomson-scattering spectrum, useful for these determinations, is often not purely Gaussian in shape, even when the probed electrons possess a Maxwellian velocity distribution. Nonetheless, an unambiguous relationship exists between electron temperatures and concentrations that truly exist in a plasma and those calculated from a distorted Thomson-scattering spectrum. Understanding this relationship permits a look-up table to be constructed, from which observed values can be corrected. Theory concerning this procedure is described and details for using it with both a ruby laser and frequency-doubled Nd:YAG laser are discussed. Examples of electron temperature and electron concentration determined with this procedure in an ICP are given. The possibility of using the new procedure to study electron-energy distributions is also assessed.

Strain Amplification of Elastomers Filled with Carbon Black in Tensile Deformation

Abstract This work is based on data previously obtained by the tensile stress-strain and dynamic-shear measurements with several gum rubbers and carbon-black-filled compounds. The gum rubbers were three NBR's of different molecular architecture and two SBR's, one of which was oil extended. The compounds contained 40 phr of N550 carbon black. Through the data treatment procedure developed in this work, the strain amplifications in the dynamic shear and tensile stress-strain measurements were evaluated with the uncrosslinked compounds. Each compound showed a unique pattern of strain amplification.

Detection and Determination of Minor Components in Nominally Pure Solids by Raman Spectroscopy

The problems encountered in applying Raman spectroscopy to direct qualitative and quantitative analysis for minor impurities in nominally pure, colorless solids have been examined. Samples of sulfamethoxazole spiked with 0.5 to 5% of sulfanilamide and sulfanilic acid were used as test materials. A procedure is described which permits detection of spectral features of the specified impurities at the 0.5% level. Least-squares fitting and cross-correlation data treatment procedures for the determination of sulfanilamide in sulfamethoxazole, with limits of detection of about 0.1% for either approach, are described. Computer simulations have been used to examine detection of impurity peaks for a variety of conditions, including the worst-case scenario in which the impurity features coincide with the strongest features of the spectrum of the host material. A least-squares fitting approach is described which permits detection of the impurity peak at the 0.5% level, even under worst case conditions.

A new ultrasonic differential method for measuring diffusion coefficients of drugs inside small gel samples. application to the diffusion of lidocaine hydrochloride and lidocaine base inside a 25% pluronic ® F-127 gel

A new method for the determination of the diffusion coefficient inside a solid matrix has been developed. The method is based on simultaneous, automatic, non-destructive measurements of the difference between the ultrasonic velocity (2 MHz) at two fixed positions within the solid matrix as a function of time. The differential technique eliminates problems arising from small temperature fluctuations and time stability of the electronics and increases the sensitivity with the result that the volume of the diffusion cell can be reduced to 1 ml. A data treatment procedure has been developed from which the diffusion coefficient can be obtained from the sound velocity data without any knowledge of the actual concentration, the partition coefficient, or possible interference of inter facial barriers. Thus the method avoids some of the substantial problems in measuring diffusion coefficients in many pharmaceutical systems. Application of the method to the diffusion of sodium chloride in a dilute gelatin gel gave a diffusion coefficient in agreement with the literature value. The diffusion coefficients of lidocaine hydrochloride and lidocaine base in a 25% (w/w) Pluronic ® F-127 gel were found to 2.5 × 10 −6 and 1.6 × 10 −6 cm 2 s −1, respectively, indicating a diffusion in the water channels between the polymer segments. Comparison with literature data obtained by the traditional release experiments showed the possible influence of the partition coefficient and the interfacial barrier on the diffusion process.

Precision Method to Determine Denaturation Temperature of Collagen using Ultraviolet Difference Spectroscopy

Ultraviolet difference spectroscopy was used to measure the thermal stability of molecular collagen under nonequilibrium conditions. A method using equipment commonly found in many laboratories and procedures for data gathering and data treatment are described. The melting temperature (Tm) was determined with high precision (S. D. : 0.10 °C) by means of close thermal spacing of recorded data. Application of curve fitting procedures on the denaturation data enhanced the recognition of details in the thermal transition. Small transitions could be discriminated and thermally located with an accuracy of ± 0.3 °C.

粒子形状の測定，解析のためのアルゴニズム

Profile data for solid particles were automatically measured by a x, y-direction scanning device. The data of several fundamental figures were simulated by the digital computer. The perimeter length, area, unrolled diameter, Feret's diameter and Fourier coefficients of the profile line were determined from those data. The procedure of data treatment consisted of border following, smoothing, interpolation and so on. The error of those geometric quantities depended on the intervals of the scanning line and some kinds of data treatment algorithms.For the periphery diameter, the accuracy (difference between computed and true values) was 1.00±0.04 and the precision (reappearency) was 1.00±0.02 when the number of divisions was about 100. For the area, unrolled and Feret's diameters, the error was 1% under the same conditions. A series of Fourier coefficients of a profile line or a particular group of them could be adopted as shape indices.

Detection of toluene diisocyanate in air with a coated piezoelectric crystal: Part 2. Development of an Instrumental Method For Personal Monitoring

Gases in the atmosphere are monitored with chemically-coated quartz piezoelectric crystals; the method is demonstrated in the use of polyethylene glycol for toluene diisocyanate determination. A microprocessor is used to control the gas sample flow through the detector head as well as the data acquisition. A computer-based procedure for data treatment permits signal integration and background drift correction, resulting in a theoretical detection limit of about 0.006 ppm. The design of a basic portable instrument for piezoelectric crystal monitoring of toxic gas is described with a view to future modification and microprocessor control.

Quantitative thermal desorption spectrometry of ionically implanted inert gases—II. Technical requirements

Experimentally, quantitative thermal desorption spectrometry requires that a well characterized sample be subjected to specified ion bombardments, heated in an accurately defined temperaturetime profile, and the resulting gas desorption rate measured with the highest available sensitivity. This paper discusses the main considerations affecting the design of the sample, its heating equipment, the ion gun and the partial pressure detector to meet these requirements. It was shown in the preceding paper that the system sensitivity and background leak rate are the only apparatus parameters affecting the accuracy with which kinetic parameters (binding energy, frequency factor, reaction order) can be derived from the data. Approximate limits to the achievable values of these two parameters are given. The required properties of the data acquisition system and the data treatment and analysis procedures are also outlined. Some experimental examples are given to illustrate the quantitative accuracies that can be attained.

A statistical method for computer treatment of elastomer flex data

AbstractIn flex testing of elastomers, the length of a cut is measured periodically as a function of the number of flexing cycles. In most cases a large number of measurements is accumulated for each test piece which would lead one to believe that the results should have a high degree of precision. This, however, is not the case, mainly because not all of the measurements are used to express the final result. Instead of being a precise test, flex testing is in fact notorious for its irreproducibility. A new method is proposed for computer treatment of flex data in which all of the flex measurements are fitted to an empirical equation by means of nonlinear regression analysis. From the fitted equation, more precise estimates of rate of growth and growth initiation point can be obtained than is possible using the data treatment procedures proposed by ASTM. Also a new index of flex life is defined which is conveniently scaled from 0–100. This so‐called flex index is a convenient index of overall flex behavior.