Magnetodynamical modes in a ferrite-filled coaxial cavity

The resonance frequencies of a coaxial ferrite-filled cavity and the field distribution in the cavity are calculated. There are three different groups of modes to be distinguished: the limit-TEM mode, the EH and HE modes, and modes independent of the zco-ordinate, which are TM modes. The eigenvalue equation for all modes is derived and discussed.     

Oxygenated fatty acids of oil from sunflower seeds after prolonged storage

Chemical analysis of a number of sunflower (Helianthus annuus) seed oil samples revealed a low and variable percentage of hydrogen bromide-reactive material. To characterize the compounds responsible for this reactivity, oil was extracted from selected introductions from Uruguay, Turkey, and Yugoslavia that had been subjected to prolonged storage. Two epoxy fatty acids and two conjugated dienolic acids were isolated from the methyl esters derived from these sunflower seed oils by using a combination of column chromatography and countercurrent distribution. The epoxy acids arecis-9,10-epoxystearic acid (0.5%) andcis-9,10-epoxy-cis-12-octadecenoic (coronaric) acid (2.2%). Characterization of the dienols revealed that they are 9-hydroxy-trans-10,cis-12-octadecadienoic acid (1.2%) and 13-hydroxy-cis-9,trans-11-octadecadienoic acid (1.3%). Fresher seed of some of these introductions contained less of the oxygenated components. Oil from recently produced seed of selected high-oil Russian sunflower varieties, including some currently grown in the United States, contained no more than trace amounts of oxygenated acids. Though the relative contributions of genetic and environmental factors toward genesis of oxygenated acids are not established, increase of those acids in some sunflower lines as a result of storage has been demonstrated. Presented at the AOCS-AACC Joint Meeting, Washington, D. C., April 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Overdamped nonlinear systems

Overdamped solutions toddot{z} + KF(z, dot{z}) = 0, z(0) = z_{0}, dot{z}(0) = dot{z}_{0}, are defined to be those that are asymptotically stable to the origin and which are zero at most once for0 < t < x. The main result is a lower bound on the positive constantKto ensure that solutions to the equation are overdamped.     

Spectroelectrochemical sensing based on attenuated total internal reflectance stripping voltammetry. 2. Determination of mercury and lead

Detection of lead and mercury by attenuated total internal reflectance spectroscopy coupled to stripping voltammetry is demonstrated. Changes in attenuation of light passing through an indium tin oxide optically transparent electrode (ITO-OTE) accompany the electrodeposition and stripping of lead and mercury on the electrode surface. The change in absorbance during stripping of electrodeposited metal constitutes the analytical response that enables detection over a range of 2.5 x 10(-7)-5 x 10(-5) and 5 x 10(-8)-5 x 10(-5) M for mercury and lead, respectively. The spectroelectrochemical responses of mercury and lead on the ITO surface are characterized and optimized with respect to solution conditions, the potential excitation signals used for deposition and stripping, and wavelength for detection. The deposited metals were examined by environmental scanning electron miscroscopy, and the electrodeposition pattern of lead and mercury was found to influence the optical response.     

Rooming-in at the maternity department. Results of a questionnaire-action

The authors report from the Univ.-Frauenklinik in Giessen, where rooming-in was first introduced in 1976; the newborn baby's bed is now put in the mother's room. When 171 outpatients, who had never heard of rooming-in, and 81 patients in the maternity ward were consulted, the women agreed to a trial period for rooming-in. It was shown that more than 70% of the women would have prefered a clinic where rooming-in was possible to a traditional type clinic. This tendency was particularly strongly felt among women with a higher level of secondary education and among women who held the view that the fathers should be more involved in the family and in the upbringing of small children. The results of individual questionnaires showed that support for rooming-in was significantly strong on the grounds of interhuman relations; also, the rejection of the traditional mother-image was apparent. Reasons for the introduction of rooming-in, as well as the difficulties involved in putting it into practice are outlined.     

SEM studies of the morphology and chemistry of polar ice

Determining the microphysical location of impurities in natural ice from the polar regions is necessary for understanding the physical properties of ice and for assuring the integrity of ice core records. SEM, using a cold stage and X-ray microanalytical techniques, has proved to be the most powerful method so far for undertaking such work. Methods are adapted from those used to study frozen hydrated biological material. Sublimation within the cryo-chamber is often needed in order to concentrate impurities onto a plane, but this can lead to artifacts that must be recognized. Over 100 samples from different depths and sites in Greenland and Antarctica have been examined. Typical physical features, including air bubbles, clathrate hydrates of air, and dust particles are identified. The dust is found preferentially at grain boundaries in some samples; by pinning the boundaries, it can slow grain growth. Of the soluble material, chloride seems to be found most frequently in the ice lattice. Other impurities are found at grain boundaries, and only when the bulk concentration exceeds a threshold, at triple junctions. These findings give new insights into processes determining the physical properties of ice samples and of ice sheets, and new impetus for theoretical studies of the energetics that lead to this distribution.     

Contents of Volume 111 (2001)

Volume Contents

Contents of Volume 111 (2001)