Familiarity, proximity and self-injurious behaviors.

This paper introduces familiarity and proximity of direct-care staff as possible contributors to the etiology of self-injurious behaviors. Analysis suggests that research workers consider these two variables when evaluating the etiology of such behaviors with specific reference to positive and negative reinforcement paradigms.

Coupled-column system for quantitating low levels of aflatoxins.

The combination of Styragel and Florisil columns allows recovery of aflatoxins at low levels. Two switching valves between the columns reduce the analysis time and exposure to solvents. Florisil is modified with oxalic acid, allowing recovery of aflatoxins at levels below 500 pg. The method is useful for contaminated corn and peanut meal samples.

Degradation of aromatic compounds in ground-water, and methods of sample preservation.

The degradation of acenaphthylene, acenaphthene, 2-methylnaphthalene, 2-methylindene, 3-methylindene and indene in water solutions was studied. These compounds at the 25-150 mug/l. level were almost totally degraded at ambient temperature within three days. The microbial population responsible for the degradation occurs naturally in ground-water taken from an aquifer in Ames, Iowa, which is contaminated with coal-tar products. These unidentified micro-organisms adapt readily to other waters when used as an inoculant for the degradation of aromatic compounds. The preservation of water to prevent such degradation was also investigated. Filtration through a 0.45-mum filter was found the most effective procedure for preserving the hydrocarbons in these waters.

Analysis of various Iowa waters for selected pesticides: atrazine, DDE, and dieldrin-1974.

Atrazine, DDE, and dieldrin were extracted and concentrated from various surface, subsurface, and finished waters using the macroreticular resin method. Organic components in the concentrates from these waters were separated by gas chromatography; the amounts of the three pesticides in the waters ranged from 0.5 to 42,000 parts per trillion by weight. Every major watershed in the State of Iowa revealed some degree of pesticide contamination and seasonal variations were consistent with agricultural runoff models. Atrazine concentrations were highest of the three pesticides, a symptom of its widespread use in the corn belt. DDE also appeared in substantial quantities, providing further evidence of the persistence of DDT and its metabolites. Water from several shallow wells and finished water from many water treatment plants were also contaminated. Current treatment processes do not effectively remove these pesticides.

Relative sensitivity coefficients for rare earths in spark-source mass spectrometry.

Relative sensitivity coefficients have been computed for rare earth elements according to empirical models which have been proposed in the literature. Explanations concerning differences between the computed and observed values are based upon possible instrumental discrimination effects which negate some processes occurring in the ion source. Computations relating elemental physical constants to observed results in a semi-random manner are shown which support this contention.

Automatic control of the ion-illumination angle in a spark-source mass spectrometer.

Automatic adjustment of only the spark-gap width in a spark-source mass spectrometer does not ensure that optimum conditions of electrode geometry are maintained with respect to the ion-optics system. A device has been developed which simultaneously maintains a constant gap width and also a more constant z-axis ion-illumination angle. This is the first development to utilize ion-optics parameters to adjust the sparking electrodes automatically. The system maintains the electrodes in an optimum configuration such that higher and more constant instrument sensitivity is maintained automatically. In addition, a significant improvement in the precision of instrumental response is demonstrated. It appears that relative isotopic abundances can be determined directly by the spark-source method which are comparable to those obtained in some cases by surface ionization or by electron bombardment. Results are given that support this contention.

A semi-automatic system for operation of electrical detection for a spark-source mass-spectrometer.

A semi-automatic control system has been developed for a spark-source mass-spectrometer, which permits close interaction between the operator, the instrument via electrical ion-detection and a computer via time-sharing (remote terminal) facilities.

Determination of rare earths in selected rare earth matrices by spark source mass spectrometry.

Three methods of preparing rare earth samples for mass spectrographic analysis are presented. Techniques for adding appropriate internal standards are described and relative sensitivity factors for rare earth impurities in rare earths, lanthanum, yttrium and scandium matrices are presented. Although indium has some value as an internal standard in rare earth samples, best analytical results are obtained when selected rare earths are used as internal standards.

Application of low-cost operational amplifiers to electrical detection in spark-source mass spectrometry.

An electrical detection system for spark-source mass spectrometry has recently been developed. This brief addendum describes an improvement in the signal amplification and its conversion to digital output which has important implications in the future development of electrical detection.

An electrical detection system for a spark-source mass spectrograph.

An electrical detection system has been developed which can be used with the high-frequency spark-source mass spectrograph. Details of the system are discussed and examples are given illustrating its advantages (rapidity and precision). One distinct advantage of electrical detection is that a constant volume of sample material is used for each impurity determination. The system can also be used to assess sample inhomogeneities.