25 Matching Results

Search Results

ORBITAL SYMMETRY CONTROL IN THE NITRONE-OXAZIRIDINE SYSTEM.NITRONE PHOTOSTATIONARY STATES

Description: Recent the orbital symmetry rules have been shown to apply to hetero-atom systems such as nitrone thermal cycloaddition reactions and the thermal and photochemical aziridine ring cleavage at the C-C bond. The concerted photocyclization is disrotatory and the reverse thermal cleavage is conrotatory in these molecules with four {pi} electrons. In contrast to the azomethine ylide-aziridine system, the stereochemistry of the nitrone photocyclization to oxaziridine can only be observed on carbon and nitrogen atoms because the oxygen atom has lone pair electrons instead of substituents. For the reverse thermal ring opening of oxaziridine to the nitrone, the two possible conrotatory motions of C-O bond cleavage should result in a mixture of the cis and trans-isomers of the nitrone, in contrast to the photoclosure which should be stereospecific.
Date: June 1, 1971
Creator: Splitter, Janet S.; Su, Tah-mun; Ono, Howard & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

SPECTROSCOPIC INVESTIGATION OF THE INHIBITORY EFFECT OF FATTYACIDS ON PHOTOSYNTHETIC SYSTEMS

Description: Fatty acids have a reversible inhibitory effect on respiration and on photosynthetic action. They investigated the influence of octanoic acid on the photosynthetic bacteria Rhodopseudomonas spheroids R-26. From the spectroscopic data they conclude that a less efficient energy transfer and decoupling of the light harvesting pigment system from the energy converting reaction center is responsible for the inhibitory effect.
Date: May 1, 1971
Creator: Steffea, Hans & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

ABSOLUTE ASYMMETRIC SYNTHESIS. I. ON THE MECHANISM OF THEPHOTOCHEMICAL ABSOLUTE ASYMMETRIC SYNTHESIS OF HELICENES WITH CIRCULARLYPOLARIZED LIGHT. . WAVELENGTH DEPENDENCE OF THE OPTICAL YIELD OFOCTAHELICENE.

Description: The synthesis of nonracemic yields of hexa-, hepta-, octa-, and nonhelicene with circular light was observed, and the structural and wavelength dependence of the induced optical yields was examined. The results obtained, together with a detailed consideration of the mechanism of helicene synthesis from the parent diarylolefins, indicate that the induced optical activity is due to selective reaction of enantiomeric conformations of the parent cis diarylolefins by circular light.
Date: May 1, 1971
Creator: Bernstein, William J.; Calvin, Melvin & Buchardt, Ole.
Partner: UNT Libraries Government Documents Department

BEAM-SURROUNDING INTERACTIONS AND THE STABILITY OF RELATIVISTIC PARTICLE BEAMS

Description: In accord with recent custom, the organizing committee for this conference has scheduled this review paper on beam instabilities. In view of the various review papers which already exist and the fact that the fundamentals of the subject have even been treated in a textbook, I thought this paper might best be devoted to a limited part of the rather large field of beam instabilities. Thus, I have selected only an aspect of the general subject, but an aspect which has during the last years been very much at the center of activity, and will--if my judgment is correct--be even more so in the years to come. I wish to concentrate, here, on the interaction of a relativistic particle beam with itself which is a result of the coupling of the beam with its surroundings. Before approaching this topic, a few remarks on the existing review papers are in order. A comprehensive treatment of beam instabilities may be found in Ref. 1, where, also, the reader will find some 48 references to the original literature. In Refs. 2 and 3, the General subject is approached from other points of view. Reference 4 is concerned with some special topics, but treats them in depth; and the text of Ref. 5 closely follows the original papers.
Date: February 1, 1971
Creator: Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department

Reaction Diffusion in the Silver-Zinc and Silver-Aluminum Systems

Description: Multiphase diffusion was investigated in the silver-zinc and silver-aluminum binary systems using metallographic and electron microprobe techniques. Diffusion couples in the silver-zinc system were prepared by electroplating silver onto coupons of a AgZn alloy (62.2% Ag), and diffusion behavior was studied at 600 and 650 degrees C. Couples in the silver-aluminum system were prepared by electroplating silver onto coupons of a AgAl alloy (87.7% Ag) and diffusion measurements were made between 400-600 degrees C. Significant deviations from equilibrium compositions were observed at the moving interphase boundary in each couple. The nucleation of a non-equilibrium silver-rich phase was observed at the location of the initial interface in many of the couples.
Date: October 1, 1971
Creator: Braun, Japnell D. & Powell, Gordon W.
Partner: UNT Libraries Government Documents Department

An Evaluation of the Use of a Quantitative Image Analyzer to Determine Microhardness Values

Description: The use of quantitative image analyzer to determine microhardness values was investigated. Microhardness traverses were made across chemically polished, partially oxidized T-111 alloy specimens using both Vickers and Knoop indenters. Microhardness values were obtained from both area and diagonal readings using a Classimat image analyzer (Classimat is a registered trademark of E. Leitz, Inc., Rockliegh, N. J.). These values were then compared with those obtained by conventional optical measurements. The data obtained by the various methods are compared and the advantages and disadvantages such as accuracy, time requirements, versatility, and limitations of particular methods are discussed.
Date: October 1, 1971
Creator: Teaney, P. E. & Selle, J. E.
Partner: UNT Libraries Government Documents Department

Muon shielding calculations: heterogeneous passive and active shields, applicat�ons to experimental beams and areas

Description: With the advent of a new generation of high-energy and high-intensity proton accelerators such as the one being built at the National Accelerator Laboratory and the one proposed by CERN, the problem of shielding external proton targets, the secondary beams produced from these targets, and even the secondary targets in the experimental areas becomes quite a massive and expensive project. In addition to the massive hadron shielding required, the high-energy muons produced by the decay of pions and kaons add large amounts of shielding especially in the forward (beam) direction. Homogeneous shields can be designed with programs which have been discussed previously. They have developed a computer program which allows them to design heterogeneous shields with voids and/or magnetic fields. The heterogeneous shields without magnetic fields are called passive shields and those with magnetic fields are called active shields. Results of some of the studies made on the design of such shields are presented. Specific application to the design of shielding for a primary external proton beam target and for a specific experiment are discussed.
Date: January 1, 1971
Creator: Theriot, D.; Awschalom, M.; Lee, K. & /Fermilab
Partner: UNT Libraries Government Documents Department

General remarks concerning some laser-initiated fusion proposals

Description: The advent of very high power, high energy pulsed laser systems has stimulated considerable thinking regarding how such systems might be used to engender thermonuclear microexplosions, and, in particular, explosions which may produce more energy than the inputted laser energy or even more energy than that used to pump the laser. Some of the basic physical principles and processes constraining laser-CTR proposals will be discussed, and application of them made to establish basic levels of feasibility of these published types of CTR schemes. It is demonstrated that this class of thermonuclear microexplosions has no potential CTR utility with lasers likely to be available in the next few years.
Date: November 1, 1971
Creator: Wood, L.; Nuckolls, J. & Zimmerman, G.
Partner: UNT Libraries Government Documents Department

AGS beam loss monitoring system

Description: No Description Available.
Date: January 1, 1971
Creator: Levine, G.S. & Balsamo, J.C. Jr.
Partner: UNT Libraries Government Documents Department

Multiturn injection into the converted AGS

Description: No Description Available.
Date: January 1, 1971
Creator: Claus, J.; Brown, H.N.; Month, M. & van Steenbergen, A.
Partner: UNT Libraries Government Documents Department

Geothermal energy: Geology, exploration, and developments. Part I

Description: Geology, exploration, and initial developments of significant geothermal areas of the world are summarized in this report which is divided into two parts. Part 1 is a review of the geological and explorational aspects of geothermal energy development; areas of potential development in the Western United States are also discussed. The most favorable geological environment for exploration and development of geothermal steam is characterized by recent normal faulting, volcanism, and high heat flow. Successful exploration for steam consists of coordinated multidisciplinary application of geological, geophysical, and geochemical knowledge and techniques. These are reviewed. California leads in known geothermal reserves and is followed by Nevada, Oregon, and New Mexico. Specific prospective areas in these 11 Western States are described.
Date: November 1, 1971
Creator: Grose, L. T.
Partner: UNT Libraries Government Documents Department

A Technique for the Metallographic Preparation of Lead

Description: A technique is described which enables lead to be metallographically prepared to reveal the true microstructure with good edge retention. The technique consists of a series of mechanical grinding and polishing steps each of which is followed by a chemical polish. The depth of the deformed metal layer, due to grinding, was measured as well as the rate of metal removed by the chemical polish. The technique can be used to achieve relatively good results in a short period of time.
Date: October 1, 1971
Creator: Downs, Gene L. & Jones, V. Dean
Partner: UNT Libraries Government Documents Department

A LIQUID-FILLED PROPORTIONAL COUNTER

Description: We report properties of single-wire proportional chambers and multiple-wire ionization chambers filled with liquid xenon. Proportional multiplication is seen for anode fields > 10{sup 6} volts/cm (anode-cathode voltage> 1 kV for a 3.5-{micro}-diam anode wire). The efficiency for detecting ionizing radiation is {approx} 100%. The time resolution of the chambers is {+-} 10{sup -7} sec. We attained a spatial resolution of {+-} 15 {micro} with a multiwire ionization chamber, considerably better than that of any other real-time particle detector.
Date: June 1, 1971
Creator: Muller, Richard A.; Derenzo, Stephen E.; Smadja, Gerard.; Smith, Dennis B.; Smits, Robert G.; Zaklad, Haim. et al.
Partner: UNT Libraries Government Documents Department