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51.
C. Schmitt A. Guessous J.P. Bocquet H.-G. Clerc R. Brissot D. Engelhardt H.R. Faust F. Gönnenwein M. Mutterer H. Nifenecker J. Pannicke CH. Ristori J.P. Theobald 《Nuclear Physics A》1984,430(1):21-60
At the recoil spectrometer “Lohengrin” of the Institut Laue-Langevin in Grenoble, the yields of the light fission products from the thermal-neutron-induced fission of 239Pu were measured as a function of A, Z, the kinetic energy E and the ionic charge states q. The nuclear charge and mass distributions summed over all ionic charge states were determined for different light fissionproduct kinetic energies between 93 and 112 MeV. The proton odd-even effect which was measured to be (11.6 ± 0.6)% causes considerable fine structure in the yields. The average kinetic energy of even-Z elements in the light fission-product group is 0.3 ± 0.1 MeV larger than for odd-Z elements. The neutron odd-even effect is (6.5 ± 0.7)%. The comparison with previously published data 1) for thermal-neutron-induced fission of 235U reveals a correlation between the proton odd-even effect in the yield and in the kinetic energy of the elements. The dependence of the proton odd-even effect on the fragmentation is very similar for 235U and 239Pu when it is considered as a function of the nuclear charge of the heavy fission products. The isobaric variances σz2. for thermal-neutron fission of 235U and 239Pu coincide at all kinetic energies if the influence of the proton odd-even effect is averaged out. This supports the hypothesis that the magnitude of σz2 is determined only by quantum-mechanical zero-point fluctuations. The influence of the spherical shells Z = 50 and N = 82 on the fragmentation is discussed. 相似文献
52.
Hopmans EC Schouten S Pancost RD van der Meer MT Sinninghe Damsté JS 《Rapid communications in mass spectrometry : RCM》2000,14(7):585-589
A method combining normal phase high performance liquid chromatography (HPLC) with positive ion atmospheric pressure chemical ionization mass spectrometry (APCI-MS) was developed for the analysis of intact glycerol dialkyl glycerol tetraethers (GDGTs) in archaeal cell material and sediments. All GDGTs previously reported to occur in the thermophilic archaeon Sulfolobus solfataricus could be identified based on their mass spectra and retention time. Positive ion mass spectra consisted of abundant protonated molecules and fragment ions corresponding to loss of water and the glycerol moiety. In addition, two novel GDGTs representing alternative combinations of biphytanyl moieties were observed. Using this method, the tetraethers present in the thermophilic archaeon Metallosphaera sedula and two sediment samples were characterized. This rapid method will greatly contribute to the establishment of the sedimentary record of these compounds and increase our understanding of archaea and their occurrence in widely different environments. 相似文献
53.
Inhaltsübersicht. Es ist gelungen, ein durch BeO stabilisiertes Bariumoxoiridat der Zusammensetzung BaIr0,67Be0,33O3 in der Kristallform eines kubischen Perowskits mit kleiner Elementarzelle erstmals darzustellen. Raumgruppe O1h–Pm3m, a = 4,1009 Å, Z = 1. Ir5+ und Be2 + besetzen die Oktaederposition des Perowskits statistisch. BaIr0,67Be0,33O3: A Stabilized Cubic Form of BaIrO3 For the first time it was possible to prepare a new barium-oxoiridate of the formula BaIr0,67Be0,33O3, stabilized by BeO. It crystallizes in a small cubic unit cell of the perovskite type. Space group O1h–Pm3m; a = 4.1009 Å; Z = 1. Ir5+ and Be2+ occupy the octahedra positions of the perovskite structure statistically. 相似文献
54.
In the framework of fusion process, ≈90% of which isg+g→c+ c, we have calculated rapidity correlation andp T /2 of charm particles produced in hadronic collisions. The experimental observation of rapidity correlation by the LEBC-EHS Collaboration is in good agreement with the calculation. From the ratio of double to single charm production an estimate of fusion cross section is made. 相似文献
55.
J. A. Kanters F. H. Van Der Steen A. Schouten Pushpa Bagdi N. S. Poonia 《Journal of inclusion phenomena and macrocyclic chemistry》1986,4(3):225-233
NH4(Pic)(DB18C6) (Pic=picrate and DB18C6=dibenzo-18-crown-6), (C26H30N4O13) FW 606.56, arthorhombic,Pmn21,a=26.045(5),b=12.055(3),c=8.982(3) Å,V=2820(1) Å3,Z=4,D
c
=1.429 g/cm3, CuK, =1.54184 Å, (CuK)=9.5 cm–1,F(000)=1272,T=298 K. The structure has been refined toR=0.0475 for 2617 unique observed reflections. In the lattice the 1:1 complex exists as a 2:2 dimer in which the crown are coupled through the Pic anions and NH4
+ cations. The asymmetric unit consists of two independent half crown ethers of which two opposite O atoms are on the mirror plane, two half ammonium cations of which the N and two H atoms are also on the mirror plane while the Pic anion is in a general position. Relative to each other, the corwn ethers are shifted by about 7.3 Å alongb and 1 Å alongc. The 1:1 sandwich of NH4 with DB18C6 and Pic on dimerisation becomes a club pseudo-sandwich with three phenyl rings on either side of the mirror plane, thus forming a nearly parallel stack with a 3.6 Å inter-ring distance. The NH4 ions hold the structure; two H atoms on the mirror plane are hydrogen-bonded to the opposite oxygens of the crown located on the purely aliphatic part of the ring (2.10(1), 2.06(3) and 2.26(3), 2.05(1) Å) for the two independent crowns, respectively, while the other two H atoms form mirror-related bifurcated hydrogen bonds with the phenoxide oxygen (1.99(1) and 2.01(1) Å) and theo-nitrogen oxygen (2.44(2) and 2.34(1) Å) of the picrates.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82037 (29 pages) 相似文献
56.
PHOTOCHEMICAL DAMAGE TO DNA TREATED WITH CHLORPROMAZINE AND NEAR UV RADIATION UNDER AEROBIC AND ANAEROBIC CONDITIONS 总被引:1,自引:0,他引:1
Double stranded salmon sperm DNA in a chlorpromazine (CPZ) solution is damaged when irradiated with near UV light. The damage of irradiated DNA can be estimated by measuring the increase in extinction at 260 nm following incubation at 60°C of the DNA with formaldehyde. Moreover, DNA irradiated in the presence of CPZ or kept in the dark separate quite differently in an aqueous polymer two-phase system. DNA irradiated in the presence of CPZ seemed to be susceptible to digestion by endonuclease S1, while the endonuclease of Neurospora crassa could not digest this DNA. Irradiation under aerobic conditions seemed to be less disastrous for DNA than under anaerobic conditions. 相似文献
57.
N De Kruijf M A Rijk L A Pranoto-Soetardhi A Schouten 《Journal of chromatography. A》1987,410(2):395-411
A thin-layer chromatographic procedure is presented for the separation and identification of preservatives that are listed in the current EEC Council Directive on cosmetic products or have been permitted in the past. The method consists of an extraction of acidified cosmetics with methanol, separation of the extracts by thin-layer chromatography on aluminium oxide and silica gel-coated plates using one developing solvent, and visualization of the preservatives on the plates using short-wavelength UV light and six detection reagents. The retention behaviour and the detectability of 88 preservatives were investigated, of which 74 were characterized by this method. The preservatives in fourteen commercial cosmetic products were tentatively identified by the procedure described. In general this method will permit the routine detection of preservatives in cosmetics in an approximate concentration of 0.1% (w/w). 相似文献
58.
59.
Applicability of the polyphenylene oxide film dosimeter to high UV exposures in aquatic environments
P.W. Schouten A.V. Parisi D.J. Turnbull 《Journal of photochemistry and photobiology. B, Biology》2009,96(3):184-192
Previous research has proven that the Poly (2,6-dimethyl-1, 4-phenylene oxide) (PPO) dosimeter is capable of receiving both in-air and underwater UV exposures that are significantly greater than those of the more commonly used polysulphone dosimeter, within a range of accuracy close to what would be expected of dosimetric measurements made in-air provided that the necessary calibrations are completed correctly by factoring in different atmospheric column ozone levels, SZA ranges, varying water turbidity and DOM levels. However, there is yet to be an investigation detailing the performance of the PPO dosimeter and its ability to measure UV in an actual field environment over an extended period of time. This research aims to bridge this gap in the knowledge by presenting a measurement campaign carried out in two real world aquatic environments and a simulated sea water environment using a batch of PPO dosimeters set at different depths and aligned to a range of different angles and geographical directions by means of attachment to a custom built dosimeter submersible float (DSF) unit over the space of a year at a sub-tropical location. Results obtained from this measurement campaign were used to compute a Kd value for the sea water in each particular season. These Kd values where found to be in close agreement to standalone Kd values derived from results taken using a standard calibrated spectrometer in the same sea water. 相似文献
60.
We consider multistage group testing with incomplete identification and unreliability features. The objective is to find a cost‐efficient group testing policy to select a prespecified number of non‐defective items from some population in the presence of false‐positive and false‐negative test results, subject to reliability and other constraints. To confirm the status of tested groups, various sequential retesting procedures are suggested. We also extend the model to include the possibility of inconclusive test results. We derive all relevant cost functionals in analytically closed form. Numerical examples are also given. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献