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  • Springer  (44)
  • American Physical Society  (28)
  • 1
    ISSN: 1572-8862
    Schlagwort(e): Copper polysulfide ; X-ray crystal structure ; infrared spectroscopy ; UV/visible spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The title compound, Cu4S10(4-methylpyridine)4 · 4-methylpyridine was prepared by three different reactions: the oxidation of copper power by sulfur and the reaction of copper (I) sulfide (or CuBr-SMe2) with cues sulfur, both in the coordinating solvent, 4-methylpyridine. Red crystals of the compound obtained by layering with hexans were subjected to single crystal X-ray diffraction. The structure was refined toR=0.026 and R w =0.036 in a space groupP1bar (No. 2), withZ=2,a=13.983 (2) A,b=15.384( 2) Å,c=9.660 (1) Å, α = 93.87 (1)°,β=93.38 =γ=(1)°,V=2037.9 (9) Å3. The commpound has approximate S4 symmetry and consists of two pentasuffide chains linking four Cu(I) ions, each with a coordinating 2-methylpyridine. The infrared spectrum was dominated by absorption due to coodinated 4-methylpyridine with several low-energy peaks attributable to S-S stretches, which were also observed by Raman spectroscopy. A featureless electronic absorption spectrum yielded a single peak in the mar ultraviolet upon computer enhancement (λ=334 nm, ε = 10,000), most likely an intraligand transition. Cyclic voltammetry indicates that the polysulfide complex undergoes irreversible oxidation and reduction at +0.04 and −0.34 V vs. SCR respectively, at NS K in 4-methylpyridine when swept at 20 mV/sec. The electrochemical behavior was unvaried even at sweep rates as high as 100 V/sec.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Origins of life and evolution of the biospheres 1 (1969), S. 520-530 
    ISSN: 1573-0875
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract An important task related to the formulation of planetary quarantine standards is the achievement of an acceptable compromise between (1) the prevention of planetary contamination and (2) the impact of quarantine requirements on the conduct of planetary missions. Such a task is a continuing effort, which must take all pertinent new information into account as it becomes available. This paper provides an analytical framework for the assessment of data which have become available during the past year or which are currently being evolved. In particular an evaluation is made of the probability of release of viable organisms from the spacecraft as a function of: (1) impact velocity magnitudes and the probability of their occurrence; (2) the degree of equipment fracturing at impact velocities; and (3) the number of viable organisms in spacecraft materials. Work being done to quantify each of three types of contamination, i.e. that on open surfaces, mated surfaces and buried contamination, is described in the context of seeking an approach to spacecraft sterilization that would be most compatible with the implementation of planetary missions. It is concluded that the results of work now in progress on spacecraft-material fracturing, on the estimation of buried contamination loads, and on microbial resistance on mated surfaces, may lead to less severe dry-heat sterilization of planetary spacecraft than had been considered necessary in the past.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Solar physics 21 (1971), S. 167-175 
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Measurements of flare-related impulsive enhancements in solar emission lines in the extreme ultraviolet, observed from the satellite OSO-III, are reported. The enhancement of a line, expressed in percent of the total disk intensity in the line, is of the same order of magnitude as the flare area, expressed in heliocentric square degrees. Rise-times and decay-times of impulsive enhancements average about 2 min and 5 min, respectively. The maximum enhancements of radiation from ions in the chromosphere-corona transition region precede the Hα maximum by an average of 2 min, and occur in the same period of time as the hard component of solar X-rays and the impulsive microwave bursts. Coronal lines in the extreme ultraviolet are less impulsive than the transition region lines in flare-related enhancements and their maxima follow the Hα maximum.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Solar physics 31 (1973), S. 411-426 
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Scanning spectrometer measurements in the range 1310–270 Å, observed from the satellite OSO 3, are reported for the solar flare of 2114 UT March 27, 1967. This flare was a long lasting sequence of bursts with EUV spectra consisting of enhanced lines and recombination continua normally emitted from the chromosphere and chromosphere-corona transition region, with unusually small increases in lines normally emited from the corona. An EUV flare spectrum is presented and suggested as one example for interpreting broadband observations of EUV bursts. Any broadband continuum other than known recombination continua contributed less than 6 % of the meassured line and hydrogen recombination continua in the range 270–1310 Å. The ratio of photon flux of Ciii 1176 Å to that of Ciii 977 Å was 0.86, which suggests an ambient density in the region of emission greater than 1012 cm-3 at temperatures near 60000 K.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Solar physics 6 (1969), S. 175-182 
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Solar electromagnetic radiation of wavelengths ranging from 260–1300 Å was measured by a grazing-incidence grating spectrometer on OSO-III, which operated as a monochromator with a wavelength bandwidth of about 2 Å and an acceptance angle covering the whole disk without any instrumental discrimination of source locations. The monochromator was commanded either to scan the whole spectrum or to operate at variously chosen fixed wavelengths. The latter mode of operation afforded a high-time resolution in the observation of temporal variations such as those associated with solar flares, and also allowed accurate determinations of the absorption characteristic of the earth's upper atmosphere (near sunset and sunrise).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Czechoslovak journal of physics 18 (1968), S. 687-688 
    ISSN: 1572-9486
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1432-0703
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik , Medizin
    Notizen: Abstract The goal of this study was to determine the influence of a range of salinities (5, 15, and 25 ppt) on the chronic toxicity of atrazine to the copepod, Eurytemora affinis during 8-day life-cycle tests. Survival, development (proportion of immature organisms) and reproduction (percent of egg-carrying females) were the endpoints used to determine chronic toxicity. Survival was the most sensitive endpoint and was therefore used to determine chronic values. The No Observed Effect Concentration (NOEC) and the Lowest Observed Effect Concentration (LOEC) at 5 ppt were 12.25 and 17.5 mg/L, respectively. The calculated chronic value was 14.6 mg/L. The NOEC and LOEC at 15 ppt were 17.5 and 25 mg/L, respectively, and the calculated chronic value at 15 ppt was 20.9 mg/L. The NOEC and LOEC at 25 ppt were 4.2 and 6.0 mg/L, respectively, while the calculated chronic value at 25 ppt was 5.01 mg/L. Results from a bootstrapping statistical technique demonstrated that there was a significant difference (p〈0.05) between chronic values at 5 ppt (14.6 mg/L) and 25 ppt (5.01 mg/L), and between 15 ppt (20.9 mg/L) and 25 ppt (5.01 mg/L). There was no significant difference between chronic values at 5 ppt (14.6 mg/L) and 15 ppt (20.9 mg/L). These specific data for atrazine have important implications for development of estuarine water quality criteria, as toxicity test results at one salinity are not representative of the salinity range found in many estuaries.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1359-5997
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung
    Beschreibung / Inhaltsverzeichnis: Resume On décrit l’application de l’imagerie de résonance magnétique nucléaire (RMN) à la mesure de distributions de teneur en eau dans le calcaire Lépine, pierre de construction type. On présente les résultats d’une expérience où l’eau est absorbée librement par capillarité de l’extrémité d’une barre rectangulaire. On utilise l’imagerie RMN pour contrôler la vitesse d’absorption de l’eau. On obtient, par l’analyse des images, les distributions à l’intérieur de l’échantillon en fonction du temps. Les distributions de teneur en eau concordent avec l’application de la théorie de l’écoulement en milieu non saturé. La diffusivité hydraulique et le coefficient de sorption se calculent à partir des profiels d’absorption d’eau. Le coefficient de diffusion de la pierre de Lépine est une fonction approximativement exponentielle de la teneur en eau, conforme aux données expérimentales des autres matériaux poreux. La meilleure estimation de la fonction de diffusion est D (m2s−1) = 6.3 × 10−9 exp (4.90θ r), oùθ r est la teneur en eau volumétrique normalisée. Le coefficient de sorption évaluée à partir des données RMN concorde tout à fait avec la mesure directe (1,00 mm min−1/2). Les méthodes d’imagerie RMN semblent prometteuses en tant que technique de laboratoire non-destructive et rapide pour déterminer les distributions d’humidité, et en particulier, mesurer avec précision les propriétés de mouvement d’eau par capillarité de matériaux poreux.
    Notizen: Abstract We report the application of proton nuclear magnetic resonance (NMR) imaging to the measurement of water content distributions in Lépine limestone, a typical constructional stone. The method is used to observe the kinetics of the absorption of water into this material by capillarity. The water content distributions are consistent with the predictions of unsaturated flow theory. The hydraulic diffusivity of Lépine stone is found to be an approximately exponential function of the water content, in agreement with experimental data on other porous materials. The best estimate of the diffusivity function is D (m2s−1) = 6.3 × 10−9 exp (4.90θ r), whereθ r is the normalized volumetric water content. The sorptivity estimated from NMR data is in close agreement with the directly measured value (1.00 mm min−1/2). NMR imaging methods appear promising as a non-destructive and rapid laboratory means of determining moisture distributions, especially for the purpose of accurate measurement of the capillary transport properties of porous materials.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 11 (1968), S. 178-181 
    ISSN: 1432-2234
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A semiempirical MO method (CNDO/2) with empirical constants adjusted to give agreement with ground state geometries has been used to study isomerization mechanism in the N2F2 system. Calculated transition states do not correspond to the simple postulated transition states.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of industrial microbiology and biotechnology 17 (1996), S. 41-46 
    ISSN: 1476-5535
    Schlagwort(e): metallothionein ; cyanobacteria ; metals ; bioremediation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract A cDNA encoding mouse metallothionein was cloned into the shuttle vector pUC303, creating a translational fusion with the bacterial chloramphenicol acetyltransferase gene. The resulting fusion protein has been expressed in the cyanobacteriumSynechococcus PCC7942. Cyanobacterial transformants expressed mouse metallothionein-specific mRNA species as detected by RNA slot blots. In addition, the transformants expressed a unique cadmium ionbinding protein corresponding to the predicted size of the mouse metallothionein fusion protein. Expression of this fusion protein conferred a two-to five-fold increase in cadmium ion tolerance and accumulation onSynechococcus PCC7942.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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