24 Matching Results

Search Results

The first weighing of plutonium

Description: The following text, transcribed from the remarks of those scientists who gathered at the University of Chicago on September 10, 1967, to celebrate the 25th anniversary of the first weighing of plutonium, tells an important part of the story of this fascinating new element that is destined to play an increasingly significant role in the future of man.
Date: September 10, 1967
Partner: UNT Libraries Government Documents Department

INELASTIC SCATTERING OF ELECTRONS BY PROTONS.

Description: No Description Available.
Date: January 1, 1967
Creator: Cone, A.A.; Chen, K.W.; Dunning, J.R. Jr.; Hartwig, G.; Ramsey, N.F.; Walker, J.K. et al.
Partner: UNT Libraries Government Documents Department

MEASUREMENT OF THE SIGMA- POLARIZATION IN THE REACTION pi- + p-->SIGMA- + K+

Description: The average polarization of the {Sigma}{sup -} produced in the reaction {pi}{sup -} + p {yields} {Sigma}{sup -} + K{sup +} has been measured between center-of-mass angles 134{sup o} and 166{sup o} for an incident {pi}{sup -} momentum of 1145 MeV/c. A polarized proton target was used, and the {Sigma}{sup -} polarization was found by measuring the difference in the production-rate of K{sup +} mesons for protons polarized along the production-plane normal and against it. Spark chambers were used to record the {pi}{sup -} and K{sup +} trajectories, and the {pi}{sup -} momentum was obtained from a magnetic spectrometer while the K{sup +} momentum was obtained from a range telescope. Each event was kinematically reconstructed in a one constraint fit to help eliminate events produced from protons bound in heavy nuclei of the target. The {Sigma}{sup -} polarization was found to be -0.36 {+-} 0.46.
Date: October 1, 1967
Creator: Weldon, D.; Steiner, H.; Shapiro, G.; Schultz, C; Johnson, C.H.; Holloway, L. et al.
Partner: UNT Libraries Government Documents Department

CHARGE TRANSFER COMPLEXES WITH HEXAFLUDROBENZENE ANDPENTAFLUOROBENZONITRILE AS ACCEPTOR COMPONENTS

Description: Charge transfer associations are a well-established phenomena and a rather extensively investigated one also. Since the acceptor component of such complexes normally does not exist as a liquid under standard conditions, they wish to report on two organic liquids which function as acceptor components with suitable complimentary molecules. As indicated in Figure 1 (the presence of an extended shoulder in the spectra of the mixture), pentafluorobenzonitrile (PFBN) complexes with N,N,N{prime},N{prime}-tetramethyl-p-phenylenediamine (TMPD), with N,N-dimethylaniline (DMA), and with phenothiazine in cyclohexane. In addition, crystalline complexes of TMPN-PFBN and DMA-PFBN are obtained when the pure materials are mixed. These two organic bases also form solid complexes with hexafluorobenzene (HFB) when the materials are mixed in the pure state in a ratio of 1:1. However, new absorption bands are not detected in the spectra (in cyclohexane solutions) of mixtures of TMPD or DMA with HFB. When HFB is used as a solvent for TMPD or DMA, the solutions are visibly yellow. However, with time a reaction occurs as evident by the formation of a black precipitate. The solid complex formed between TMPD-PFBN, which is orange, was analyzed by a combination extraction and spectroscopic method and by vapor phase chromatography and found to contain a ratio of the two components of 1:1 which agrees with an elemental analysis of this complex. Analysis of DMA-PFBN or DMA-HFB complexes were complicated by the presence of excesses of the liquid components on the crystalline complexes. When attempts are made to dry the crystals, the crystals dissociate as the excesses evaporate until the crystals and the two components totally disappear. The TMPD-HFB complex was not analyzed. The complex between phenothiazine and PFBN as not isolated as a crystalline material. The association constants for the TMPD-PFBN and MDA-PFBN complexes were determined according to the method of Hildebrand and Benesi. The ...
Date: October 31, 1967
Creator: Corker, Gerald A. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department

ORGANIC GEOCHEMICAL STUDIES. I. MOLECULAR CRITERIA FOR HYDROCARBONGENESIS

Description: In recent years the search for life-forms at the earliest periods of geological time has been continued not only at the morphological level but also at the molecular level. This has been possible as a result of the increase in the biochemical knowledge and with the advent of analytical techniques that are capable of describing the intimate molecular architecture of individual molecules in acute detail. The fundamental premises upon which this organic geochemical approach rest are the following: that certain molecules, possessing a characteristic structural skeleton, show a reasonable stability to degradation over long periods of geological time; that their structural specificity can be understood in terms of known biosynthetic sequences; and that their formation by any non-biological means is of negligible probability. In this manuscript it is proposed to critically re-examine these premises and to establish criteria whereby one can differentiate molecules derived from biological systems from those that have their origin in non-biological processes. The importance of establishing such criteria lies in the significance these criteria have in determining whether life exists, or has existed, on other planets. Within the very near future it may be possible to provide an initial answer to this question when the first lunar samples are returned to the earth for analysis.
Date: September 22, 1967
Creator: McCarthy, Eugene D. & Calvin, Kevin
Partner: UNT Libraries Government Documents Department

ORGANIC GEOCHEMICAL STUDIES. II. THE DISTRIBUTION OF ALIPHATICHYDROCARBONS IN ALGAE, BACTERIA, AND IN A RECENT LAKE SEDIMENT: APRELIMINARY REPORT

Description: The theory that algal oozes could give rise to oil shales is not a recent one. Evidence for this theory rests on the finding that algae have less cellulose and a correspondingly greater proportion of lipids than most plant material. In addition, the contemporary alga Botyrococcus is present in microscopic remains in some organic oozes. Since the algal ooze precursor theory rests primarily on geological and paleobotanical evidence, they have sought to complement this evidence by making a study of the constitutents of various genera of algae at the molecular level and comparing them with the organic constituents isolated and identified in the algal ooze from a Florida lake. They have analyzed the hydrocarbon constituents of four species of algae: the blue-greens, Nostoc and Anacystis, the green algae, Spirogyra and Chlorella.
Date: November 1, 1967
Creator: Han, Jerry; McCarthy, E.D.; Van Hoeven Jr., William; Calvin,Melvin & Bradley, W. H.
Partner: UNT Libraries Government Documents Department

PRODUCT ENERGY AND ANGULAR DISTIBUTIONS FROM THE REACTION OP N2+WITH ISOTOPIC HYDROGEN MOLECULES

Description: The energy and angular distributions of N{sub 2}H{sup +} and N{sub 2}D{sup +} formed when a beam of N+2 passes through a scattering cell containing H{sub 2}, D{sub 2}, or HD have been measured at relative kinetic energies ranging from 2.3 to 11.6 eV. From some experiments, intensity contour maps that show the complete product velocity vector distribution in the centre of mass system have been generated. Although backward recoil scattering occurs at all energies, most products are scattered forward in the centre of mass system. The shape and position of the forward scattered product peak are largely consistent with the stripping model modified to account for target motion.
Date: June 1, 1967
Creator: Gentry, W.R.; Gislason, E.A.; Lee, Yuan-tseh; Mahan, B.H. & Tsao,Chi-wing.
Partner: UNT Libraries Government Documents Department

IRRADIATION OF 3- SUBSTITUTED-2-PHENYLOXAZIRIDINES

Description: It was noted previously that 3-(p-dimethylamino)-2-phenyloxaziridine (I) and 3-(p-dimethylamino)-2-(m-nitrophenyl)oxaziridine were photosensitive. Further study on the irradiation (in a variety of solvents under nitrogen) of (I), 2,3-diphenyloxaziridine (II), and 3-(p-nitrophenyl)-2-phenyloxaziridine (III) indicates the major photoreaction to be cleavage to the aldehyde and an intermediate which forms aniline and azobenzene. There is also formed in the photolysis varying amounts of the corresponding anilide. A table provided gives the yields in three different solvents.
Date: August 30, 1967
Creator: Splitter, Janet S. & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

THERMODYNAMICS OF LIGHT EMISSION AND FREE-ENERGY STORAGE INPHOTOSYNTHESIS

Description: A Planck law relationship between absorption and emission spectra is used to compute the fluorescence spectra of some photosynthetic systems from their absorption spectra. Calculated luminescence spectra of purple bacteria agree well but not perfectly with published experimental spectra. Application of the Planck law relation to published activation spectra for Systems I and II of spinach chloroplast permits independent calculation of the luminescence spectra of the two systems; if the luminescence yield of System I is taken to be one-third the yield of System II, then the combined luminescence spectrum closely fits published experimental measurement. Consideration of the entropy associated with the excited state of the absorbing molecules is used to compute the oxidation-reduction potentials and maximum free-energy storage resulting from light absorption. Spinach chloroplasts under an illumination of 1 kilolux of white light can produce at most a potential difference of 1.32 eV for System I, and 1.36 eV for System II. In the absence of non-radiative losses, the maximum amount of free energy stored is 1.19 eV and 1.23 eV per photon absorbed for Systems I and II, respectively. The bacterium Chromatium under an illumination of 1 milliwatt/cm{sup 2} of Na D radiation can produce at most a potential difference of 0.90 eV; the maximum amount of free energy stored is 0.79 eV per photon absorbed. The combined effect of partial thermodynamic reversibility and a finite trapping rate on the amount of luminescence is considered briefly.
Date: April 1, 1967
Creator: Ross, Robert T. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department

TRITIUM INCORPORATION STUDIES IN PHOTO-SYNTHETIC BACTERIA

Description: Although the detailed pathway of carbon, by which carbohydrates are formed from carbon dioxide during photosynthesis, has been established, comparatively little is known about the participation and transport of hydrogen in the complex series of reactions now known to be involved in photosynthesis. The transport of hydrogen may occur concurrently with the redox reactions of photosynthetic electron transport leading to the formation of ATP, as well as in the reduction of carbon dioxide. The participation of the chlorophylls, the carotenoids, the quinones, and other lipoid components in photosynthetic hydrogen transport has been the subject of considerable speculation. In an attempt to elucidate the pathway of hydrogen transport, we are studying the tritium labeling pattern in the lipid extracts of Rhodospirillum rubrum after the bacteria have been illuminated in growth medium containing tritiated water.
Date: July 1, 1967
Creator: Dehner, Thomas R.; Chan, W.-S.; Caple, Marianne B. & Calvin, M.
Partner: UNT Libraries Government Documents Department

VOLATILE SILICON COMPLEXES OF ETTOPORPHY-RIN I

Description: The presence of several homologous series of porphyrins have been demonstrated in some oil shale rocks, shale oils, and petroleums. However, the application of microanalytical techniques (i.e., mass spectrometry and gas chromatography) to structure determination has been limited due to the low volatility of the porphyrin components. The authors report the synthesis of several novel Si(IV) etioporphyrin I derivatives and the effects that their various additional silicon ligands have on porphyrin volatility as measured by gas chromatography at normal pressure.
Date: July 31, 1967
Creator: Boylan, D.B. & Calvin, M.
Partner: UNT Libraries Government Documents Department

THE PHOTOCHEMISTRY OF PYRIDINE N-OXIDE

Description: The authors wish to report their results on the photolysis of pyridine N-oxide in alcoholic solution. Both methanol and ethanol solutions of pyridine N-oxide were irradiated. The reaction mixture was analyzed by gas-liquid chromatography (GLC) using a 2.5% FFAP on Chrom G column and a Porapak Q column. In order to collect the products, the volume of the photolysis solution was reduced in vacuo and the resulting mixture was separated by preparative GLC.
Date: September 14, 1967
Creator: Alkaitis, Algis & Calvin, Melvin.
Partner: UNT Libraries Government Documents Department

Proceedings of the First International Symposium on the Biological Interpretation of Dose from Accelerator-Produced Radiation, Held at the Lawrence Radiation Laboratory, Berkeley, California, March 13--16, 1967

Description: The objective of the meeting was to provide a companion meeting to the ''First Symposium on Accelerator Radiation Dosimetry and Experience'' which was held November 3-5, 1965, at the Brookhaven National Laboratory. This first symposium was limited in scope to an intensified discussion of dosimetry techniques. The biology which is associated with high energy radiation was specifically excluded, since it was the original plan to hold a second symposium devoted entirely to biology. Thus the present Symposium was a sequel to the first and they were inseparable in their objectives. Since those attending the BNL Symposium were almost entirely health physicists with a background in physical science and actively engaged in the solution of radiation protection problems at high energy accelerators, it was felt that it would be necessary to begin the BID Symposium with a general review session on radiation biology, in order to provide a biological background for the proper understanding of the later sessions. This first session was arranged to give the health physicist a meaningful transition from fundamental radiobiological considerations to current new research activities in high energy biology. In our opinion, and also based on the comments of several of those attending these objectives were quite well attained. The talks by Bond, Robertson, Brustad, Wolff, and Patt were quite exhaustive as an introduction to the several areas of specialization in radiobiology. The overall purpose of the meeting was of course to inform the health physicists about the state of knowledge in advanced biological research as it might apply to their problems. It has often been said that it takes a long time for laboratory findings to be applied in practical situations, but this is certainly not true in radiobiology. Through this conference and others like it, the most recent understanding of high energy radiobiology is ...
Date: March 13, 1967
Creator: Wallace, R.
Partner: UNT Libraries Government Documents Department