A High Frequency Oscillometric Technique for the Analysis of Various Chlorides

This study involved the use of an oscillometric technique for the quantitative analysis of various chlorides such as sodium, potassium, calcium and aluminum chlorides. This technique depends on the determination of the capacitance of aqueous solutions of varying normality and the generation of a calibration curve as a function of concentration. These calibration curves for each salt were computerized by means of a modeling equation of a nonlinear type. This gave a parameter set of values which were iterated to constant value and uniquely defined for a particular calibration curve. The results of the quantitative assay of various chlorides was found to be accurate to within two percent and compared favorably with and is somewhat more accurate than a silver nitrate titration with a fluor-cein indicator.     

Propagation and radiation characteristics of the tape helix with aconducting core and dielectric substrate

An equation is presented to describe the dispersion characteristics of a tape helix separated from a concentric conducting core by a dielectric substrate. Numerical solutions of the complex-valued propagation constant can be used to obtain the complete k-β diagram of the helical geometry. The k-β diagram provides information regarding the real-valued solutions for β that represent true axial propagation, as well as the complex-valued solutions that represent surface waves and leaky waves. Several different helix geometries are considered. Under the assumption that these same solutions exist on a finite-length structure, the radiation pattern can be obtained for a given mode of propagation     

Progressive Changes in the Structure of Hardened C3S Cement Pastes due to Carbonation

The structures of partially carbonated hardened C₃S cement pastes have been investigated by a combination of ²⁹Si magic angle spinning nuclear magnetic resonance spectroscopy and analytical transmission electron microscopy, supported by X-ray diffraction and thermogravimetric analysis. Progressive changes in structure are reported for thin slices for a paste carbonated in pure CO₂ for times from 1 to 16 h, and the results are compared with those for a paste carbonated for 2 months in air. C-S-H gel of reduced Ca:Si ratio and increased silicate polymerization was formed during the early stages of carbonation. The morphology of the original C-S-H was, in the main, retained. A cross-linked silica-rich gel formed at later times in paste carbonated in CO₂ but not up to the time of 2 months in air. Calcium carbonate took the form of microcrystals of vaterite and calcite which formed dense masses between gel fibrils and around partially reacted CH crystals, possibly accounting for the observed slowing in the rate of reaction of CH with time.     

Steric and Electronic Effects in Basic Dyes

Absorption spectra of nine derivatives of Malachite Green containing two or three methoxy groups in the phenyl ring have been examined. In the absence of varying steric effects an excellent additive relationship is found between the electronic effects of the substituents and the position of the first electronic absorption band. Conformational changes brought about by crowding substituents are detected by an increase in intensity of the first band accompanied by a decrease in intensity of the second band.     

Reversal of innate aversions: Attempts to induce a preference for chili peppers in rats.

Although humans frequently develop preferences for innately unpalatable bitter or irritant substances, such preferences are extremely rare in animals. An attempt was made to understand the nature of this difference by 5 experiments with Charles River albino rats, using chili pepper as the unpalatable substance. In parallel with major aspects of the human experience with chili pepper, Ss were exposed to it as a flavoring in all their food for periods up to 11 mo from birth without significant preference enhancement. Gradual introduction of chili into the diet also had no effect, nor did poisoning and safety experiences designed to teach Ss that only chili-flavored foods were safe to eat. Seven pairings of chili-flavored diet with prompt recovery from thiamine deficiency did significantly attenuate the innate aversion and may have induced a chili preference in at least 1 case. Extensive experience with chili did not reliably make Ss much less sensitive to its oral effects. The only reliable way to eliminate chili aversion in rats is to destroy their chemical irritant sense, which was accomplished in 1 group. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Specificity of acquired aversions to taste qualities in hamsters and rats.

372 golden hamsters and 120 Sprague-Dawley rats tasted 1 of 27 solutions before receiving an ip injection of apomorphine, then were tested for aversions to 4 solutions prototypic of human taste qualities: sucrose, NaCl, HCl, and quinine HCl. With most of the solutions described as sweet employed as CSs, Ss acquired an aversion to sucrose. With CSs described as either salty or sour by humans, Ss acquired an NaCl aversion in the former case or an HCl aversion in the latter case; an aversion to quinine HCl was acquired with 2 of the 3 CSs described as sour. With most of the CSs described as bitter or as having a bitter component, Ss acquired a quinine HCl aversion. Patterns of S activity evoked across 4 classes of peripheral gustatory neurons when the CSs were applied to the tongue were similar to the patterns of aversions across the 4 test stimuli for the CSs. This suggests that 4 neural channels mediate the sensations evoked by the 4 test solutions in rats and hamsters, perhaps even in human beings. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of verbal evaluation feedback and interpersonal distance on behavioral compliance.

80 female clients were individually interviewed in the context of a weight-reduction clinic. In a 2 * 2 factorial design, a counselor offered either accepting or neutral verbal feedback for a client's self-disclosures and sat either at a "personal" or "social" distance from the client. A significant interaction was obtained, which showed that physical proximity strengthened adherence to a counselor's dieting recommendations when accepting feedback was offered and lowered compliance when neutral feedback was expressed. Results are discussed in terms of the notion of consistency in communicative channels. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microfabricated differential mobility spectrometry with pyrolysis gas chromatography for chemical characterization of bacteria

A microfabricated drift tube for differential mobility spectrometry (DMS) was used with pyrolysis-gas chromatography (py-GC) to chemically characterize bacteria through three-dimensional plots of ion intensity, compensation voltage from differential mobility spectra, and chromatographic retention time. The DMS analyzer provided chemical information for positive and negative ions simultaneously from chemical reactions between pyrolysis products in the GC effluent and reactant ions of H+(H2O)n and O2-(H2O)n in air at ambient pressure. Authentic standards for chemicals formed in the pyrolysis of bacteria showed favorable matches with plots from py-GC/DMS analysis and were supported by py-GC/MS results. These and other yet-unidentified constituents provided a means to distinguish Escherichia coli from Micrococcus luteus. A Gram-positive spore former (Bacillus megaterium) was distinguished by an abundant peak for crotonic acid evident in positive and negative ions and not observed with M. luteus. In contrast, plots from py-GC/DMS of lipid A and lipoteichoic acid showed poor matches to plots for a Gram-negative (E. coli) bacterium and a Gram-positive (M. luteus) bacterium and the differences were attributed to differences in genus sources of the biopolymers. A significant percentage of the chemical information available in py-GC/DMS is unidentified, and the analytical utility must be established. Precision in the chemical measurement was determined as +/- 0.2 V, 10% relative standard deviation (RSD), and +/- 0.05 min for compensation voltage, peak intensity, and retention time, respectively. The minimum number of total bacteria (cell forming units) detected was 6000 though detection limits and resolution could be varied by the magnitude of the separation voltage in the differential mobility spectrometer.     

A video-based movement analysis system to quantify behavioral stress responses of fish

Behavioral alterations can be measured as endpoints for sublethal toxicity, and serve as a tool for environmental risk assessment and analysis of toxicological impact. Numerous technical and biological factors have made sublethal effects on fish behavior difficult to quantify. In order to investigate stress- and contaminant-induced behavioral alterations, a video analysis system was designed by our laboratory. With this system up to 12 fish may be individually housed in 20 L exposure arenas and automatically videotaped at multiple and discrete intervals during an experimental period. Analog video data can then digitized, converted into x,y coordinates, and finally transformed into relevant behavioral endpoints using software designed for tracking fish movement combined with specific algorithms. These endpoints include velocity, total distance traveled, angular change, percent movement, space utilization, and fractal dimension (path complexity). Data from fish exposed to a reference toxicant, MS222, and simulation experiments, are presented to exemplify alterations in fish behavior associated with exposure, and accuracy and precision, respectively. The system provides flexibility to analyze any observed movement behavior, is remotely controlled, and can be transportable. These movement analyses can be used to identify characteristic behavioral responses to a variety of environmentally-relevant stressors, and assist in risk assessment and the development of more sensitive lowest observable effect level and no observable effect level for sentinel species.