Showing papers by "University of Notre Dame published in 1980"

Electrophilic reaction of the hydroxyl radical with phenol. Determination of the distribution of isomeric dihydroxycyclohexadienyl radicals

Abstract: Using pulse radiolysis with optical detection and high-pressure liquid chromatography techniques it is shown that the isomeric dihydroxycyclohexadienyl radicals formed in aqueous solution by reaction of OH with phenol react with quinones by electron transfer to yield semiquinones and dihydroxybenzenes. The rate constants for these electron-transfer reactions depend on the redox potential of the quinone and on the isomer structure of the dihydroxycyclohexadienyl radical; i.e., the rate constants are large (10/sup 7/-10/sup 9/M/sup -1/s/sup -1/) in the case of the ortho and para isomers and small (less than or equal to 10/sup 7/M/sup -1/s/sup -1/) in the case of the meta and ipso isomers. The isomeric dihydroxycyclohexadienyl radicals differ also with respect to their rates of H/sup +/-catalyzed dehydration to yield phenoxyl radical. It is thus possible to distinguish kinetically between the different dihydroxycyclohexadienyl radicals. On this basis and from the product analysis data the fractions of OH attack at the ipso, ortho, meta, and para position of phenol are 0.08, 0.48, 0.08, and 0.36, respectively. These data show the strong preference of the electrophilic OH radical for attack at the ring positions activated by the phenolic OH group.

Laminar Separation, Transition, and Turbulent Reattachment near the Leading Edge of Airfoils

Abstract: The laminar separation, transition, and turbulent reattachment near the leading edge of a cylindrical noseconstant thickness airfoil model were investigated using a low-turbulence, low-speed smoke wind tunnel. The locations of separation, transition, and reattachment were obtained from smoke flow photographs and surface oil flow techniques for chord Reynolds numbers from about 150,000 to 470,000. These visual data combined with static pressure distributions delineate the effects of angle of attack, flap deflection angle, and chord Reynolds number on the separation bubble characteristics. The data concerning the length of the laminar and turbulent portions of the bubble agree with the empirical prediction methods for short bubbles.

Relativistic Random-Phase Approximation

Abstract: The relativistic random phase approximation RRPA is developed from linearized time-dependent Hartree-Fock theory. Applications of the resulting relativistic many-body equations to determine excitation energies and oscillator strengths along the He, Be, Mg, Zn and Ne isoelectronic sequences are discussed and compared with other recent experimental and theoretical work. The multi-channel RRPA treatment of photoionization is described and applications are given to total cross sections, branching ratios, angular distributions and to autoionizing resonances.

Analysis of Beutler-Fano autoionizing resonances in the rare-gas atoms using the relativistic multichannel quantum-defect theory

Abstract: The Beutler-Fano autoionizing resonances in the rare-gas atoms argon, krypton, and xenon are studied using the relativistic multichannel quantum-defect theory (MQDT). Dynamical parameters for the MQDT analyses are obtained from an ab initio relativistic-random-phase-approximation calculation. The position and profile of these resonances are in good agreement with experimental measurements. Angular distribution and spin polarization of photoelectrons in the resonance regions are also studied and are in close agreement with recent measurements.

The background and some current problems of theoretical ecology

Abstract: The term ‘Oekologie’ was coined in 1866 by Ernest Haeckel in a book relating animal morphology to Charles Darwin’s then new theory of evolution by natural selection. Haeckel claimed that the theory of evolution explained and formed the groundwork of ecology. This natal link with the premier theory of biology was quite clear in the minds of early American ecologists. S. A. Forbes (1895) allowed that the whole Darwinian doctrine belonged to ecology. J. C. Arthur (1895) wrote, “We may call Darwin the father of vegetable ecology, for had he not written, the field would have lain largely uncultivated and uninteresting”. H. C. Cowles (1904) was equally explicit, “If ecology has a place at all in modern biology, certainly one of its great tasks is to unravel the mysteries of adaptation”; and J. G. Needham (1904) described it as, “the study of the phenomena of fitness”. The Darwinian derivation and emphasis of ecology has also been noted by historians of science. R. C. Stauffer (1957) asserted, “As a source for a vital stimulus to the continuing development of ecology we must look rather to the work of Charles Darwin”. R. Tobey (1976) wrote the “great theoretical synthesis” of ecology by Darwin was generally assumed by historians; and D. Worster (1977) developed the Darwinian base for ecology in detail. Recent ecologists, like John Harper (1967), reclaimed the theory of natural selection as an ecological theory, and Darwin as “the greatest of all ecologists”, but complained that Darwinian ecology had been largely neglected by ecologists.

Direct Measurement of the Negative-Kaon Form Factor

Abstract: The electromagnetic form factor of the negative kaon has been measured by direct scattering of 250-GeV/c kaons from the stationary electrons of a liquid-hydrogen target The deviation of the measured elastic scattering cross section from the point cross section may be characterized by a root-mean-square kaon radius of 〈rK−2〉12=0.53±0.05 fm.

Factors involved in overwintering survival of the freeze tolerant beetle,Dendroides canadensis

Abstract: Overwintering larvae of the beetle,Dendroides canadensis, from northern Indiana were able to survice freezing at temperatures down to −28°C. During a late winter thaw or upon warm acclimation the larvae became freeze susceptible, but cold acclimation or acclimatization restored freeze tolerance. Concentrations of the cryoprotectants glycerol and sorbitol, ice nucleating agents (probably proteins) and thermal hysteresis proteins increase in the autumn, peak in winter and decline in spring. These and other, as yet unknown, factors are responsible for the capacity ofDendroides to survice subzero temperatures. The hemolymph ice nucleating agents limit the amount of undercooling to approximately 1°C below the hemolymph freezing point and thereby prevent lethal intracellular ice formation. Therefore, the freezing point depression provided by the thermal hysteresis proteins becomes essential to the survival of the larvae during periods such as winter thaws, autumn, and spring when the larvae are freeze susceptible.

A self-instructional package for increasing attending behavior in educable mentally retarded children.

Abstract: The purpose of this study was to develop a self-instructional package that would aid highly distractible children in increasing their attending behavior in a training and two generalization (a one-to-one and a classroom) situations. Three untrained subjects were monitored for general comparison and social validation purposes. One of these control subjects was distractible and the other two (criterion comparison) were evaluated as not having attentional problems. A multiple baseline design was employed in which training was sequentially introduced across subjects. During training, the experimental subjects were taught through self-instruction to focus their attention and to cope with two tasks, math and printing. After learning the self-instructions the subjects were systematically and sequentially exposed to photo-slides of distracting situations, to audio-distractors composed of noisy lunchroom verbal peer interactions, and to in vivo distractors provided by kindergarten children playing with wooden blocks in the training setting. The entire training procedure was handled in a game-like context to maintain subject interest and to facilitate generalization. The results suggested that the training package produced direct and generalized changes in self-instructional behavior. In addition, a decreae in off-task behavior occurred during math, printing, and also during a phonics program in the one-to-one and classroom situations. However, reliable changes in academic task performance were not observed. Finally, no systematic changes on any of the dependent measures occurred for the three untrained subjects.

The function and meaning of work and the job: Morse and Weiss (1955) revisited.

Abstract: The article presents the results of a study that revisits an earlier study pertaining to the function and meaning of work. The original study asserted that the function of work as a purely an econo...

Proximity electron tunneling spectroscopy I. Experiments on Nb

Abstract: A quantitative proximity electron tunneling spectroscopy (PETS) is demonstrated for the study of strong coupling superconductors which do not form suitable insulating oxides for conventional McMillan-Rowell tunneling spectroscopy. Proximity junctions of the form C-Al2O3-Al/S are employed, with Al thickness d N ≤ 100 ». Here S is the superconductor of interest and C is any convenient counterelectrode. The physical basis for the method, experimental techniques, and data obtained from foils of Nb are presented. The results for Nb include the energy-dependent pair potential δS(E), the renormalization function Z(E), effective phonon spectrum α 2 F(Ω), electron-phonon coupling constant λ, and Coulomb pseudopotential Μ*. A full discussion of the underlying theory and details of the methods of analysis employed to obtain, in addition, the pair potential of the Al proximity layer are contained in a following paper.

Latin America in caricature

Abstract: * Acknowledgments *1. Introduction *2. The Hemisphere as Monolith *3. Latin America as Female *4. The Republics as Children *5. The Republics as Blacks *6. The Latin American Nations as Non-Black Males *7. Social Reform and Militarism *8. Conclusion * Notes * Index

Performance of bilinguals in a picture-word interference task

Abstract: The picture-word interference task was administered to Spanish-English adults in order to determine whether the lexicons of bilinguals are integrated or whether words are stored and accessed separately in semantic memory. Pictures were printed with Spanish words naming other objects, with English translations, and with X's. Spanish and English distractor words were observed to slow down picture naming in both languages. Also, an interaction was detected among subjects naming pictures in English. On the first trial Spanish words produced more interference than English words, whereas the pattern was reversed thereafter. This effect is attributed to task novelty, which disappears with practice. No differential patterns of interference were observed among subjects naming pictures in Spanish, probably because of greater error variance. Results for English picture-naming bilinguals supported the integration hypothesis but suggested that there is less distance between words within a language than between languages in semantic memory.

The Logic of Invention

Abstract: “Is there a logic of discovery?” has been a continuing if not central question of philosophy of science ever since Hanson’s flamboyant defense of an affirmative answer. The question presupposes a distinction — attributed to Reichenbach — between discovery and justification as distinct (logically and perhaps temporally) stages of scientific inquiry. Justification of course, it is said, has a logic (explicated, e.g., by theories of confirmation); but most have thought discovery a nonrational process, amenable only to causal explanation. Hanson and a few others, including myself in (1973b), have contended that discovery has a distinctive logical structure and that explication of this structure will open philosophy of science to important but hitherto neglected aspects of scientific practice.

Tunneling and the electron-phonon-coupled superconductivity of Nb 3 Sn

Abstract: A substantially improved description of published electron-tunneling spectra from ${\mathrm{Nb}}_{3}$Sn is obtained by taking account of a probable surface proximity layer in the junctions studied. The results satisfactorily describe the superconducting properties of ${\mathrm{Nb}}_{3}$Sn within the conventional framework of strong electron-phonon coupling theory, with $\ensuremath{\lambda}=1.8\ifmmode\pm\else\textpm\fi{}0.15$, ${\ensuremath{\mu}}^{*}=0.16\ifmmode\pm\else\textpm\fi{}0.03$.

Colloidal Silver Catalyzed Multi-Electron Transfer Processes in Aqueous Solution

Abstract: (CH3)2COH radicals were γ-radiolytically produced in aqueous solutions of colloidal silver (2.5 · 10−4 mol/l, acetone (0.1 – 0.2 M) and propanol-2(0.2 – 0.4 M). The radicals were able to reduce Cd2+, N2O, and NO−3 with yields of practically 100%. In the absence of colloidal silver, Cd2+ was not reduced, but N2O or NO−3 were reduced with yields of the order of 1%. The reduction processes in the presence of silver occurred in competition with the reduction of water by the organic radicals. The catalytic action of colloidal silver is explained by electron transfer from the organic radicals to the silver particles that become a pool of electrons and adsorbed hydrogen atoms. The stored electrons are then used to carry out the reduction of water or of dissolved substances. Relative rate constants for a number of multi-electron transfer processes at the colloidal silver pool are given and details of the reaction mechanism including the action of adsorbed Hδ- atoms are discussed. — Radiolytically produced Cd+ ions were also reduced at the colloidal silver pool. However, Zn+, Ni+, and Co+ were found to transfer an electron to the pool. The homogeneous reaction between NO−3 and (CH3)2COH was also investigated. A rate constant of 28 M−1 s−1 was found for this reaction. (CH3)2COH-Radikale, die in wasrigen Losungen von kolloidalem Silber (2,5 · 10−4 mol/l, Azeton (0,1 – 0,2M) und Propanol-2(0,2–0,4M) durch γ-Bestrahlung erzeugt werden, vermogen Cd2+, N2O und NO-3 mit Ausbeuten von praktisch 100% zu reduzieren. In Abwesenheit von kolloidalem Silber wird Cd2+ nicht reduziert und N2O und NO-3 nur mit Ausbeuten um 1%. Die Reduktionsprozesse in Gegenwart von Silber konkurrieren mit der Reduktion des Wassers durch die organischen Radikale. Die katalytische Wirkung des kolloidalen Silbers wird durch die ubertragung von Elektronen von den organischen Radikalen zu den Silberteilchen erklart, so das die letzteren zu einem Speicher von Elektronen und adsorbierten H-Atomen werden. Die gespeicherten Elektronen werden dann zur Reduktion des Wassers oder der gelosten Substanzen verwendet. Relative Geschwindigkeitskonstanten fur eine Reihe von multi-Elektronen-ubertragungsreaktionen am kolloidalen Silberspeicher werden mitgeteilt und Details des Reaktionsmechanismus, der auch die Wirkung von adsorbierten Hδ--Atomen einschliest, diskutiert. — Durch Strahlung erzeugte Cd+-Ionen werden ebenfalls am kolloidalen Silberspeicher reduziert. Zn+, Ni+ und Co+ ubertragen dagegen ein Elektron an den Speicher. Die langsame homogene Reaktion zwischen NO−3 und (CH3)2COH-Radikalen wurde ebenfalls untersucht. Eine Geschwindigkeitskonstante von 28 M−1 s−1 wurde fur diese Reaktion gefunden.

The design, fabrication and evaluation of a trileaflet prosthetic heart valve.

Abstract: Although prosthetic heart valves have been in existence for many years, the need for new improved designs and in-vitro evaluation techniques are apparent. This paper presents details on the design considerations, fabrication techniques and heart valve evaluation equipment. A valve performance index is discussed in light of various valve and mock circulatory test section designs. The need for national and indeed international valve evaluation techniques is made apparent.