ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of chloramphenicol (1979)
    Springer
    Journal of chemical crystallography 9 (1979), S. 295-304 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Chloramphenicol, C11H12Cl2N2O5, is orthorhombic, space groupC2221,a = 17.495(3),b = 7.321(2),c = 22.130(4) Å, andZ = 8. The structure was solved by direct methods and refined to a finalR value of 0.068 for 1186 counter-reflections. Estimated standard deviations for bond lengths and bond angles involving nonhydrogen atoms average 0.009 Å and 0.6 °, respectively. All the hydrogen atoms that are bonded to O or N and are available for hydrogen-bond formation take part in the hydrogen-bonding network. The crystals become brown in color on prolonged exposure to X-rays and γ-rays. Our structural investigation with colored crystal does not indicate any structural change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01200521
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Paramagnetic resonance of the (Cr5+O4)H2 Halperin-Varma center in NH4H2AsO4 and KH2AsO4 (1978)
    Springer
    The European physical journal 31 (1978), S. 151-163 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electron paramagnetic resonance (EPR) spectrum of Cr5+(3d 1,S=1/2) in undeuterated and 58%-deuterated NH4H2AsO4 was investigated. The EPRg-value tensors in the paraelectric and antiferroelectric phases are almost the same as those observed at high and low temperatures in KH2PO4 and KH2AsO4. This shows that the (Cr5+O4)H2 complex is the same in all crystals, i.e., a wave function ofd x 2−y 2 character coupled to two lateral protons which reorient among the four possible Slater configurations in the paraelectric phase. The remarkable isotope shift of the local dynamic reorientational slowing-down observed in KH2PO4 and KH2AsO4 in approximate proportion to the shift of the bulk ferroelectric transition temperaturesT c F , and the antiferroelectricT c AF of NH4H2AsO4, is analyzed qualitatively. It is shown to result mainly from the isotope effect of the short-range interactionJ sr via protons and deuterons for the impurity and for the bulk. Q-band data of the (Cr5+O4)H2 center in 75%-deuterated KH2AsO4 are also reported. An averaged high- and nonaveraged low-temperature EPR spectrum is observed in a temperature range of 250 to 290 K. The intensity ratio of the two follows an exp 2(T′—T)/Δ law over four orders of magnitude atT=266 to 273 K andΔ=5.3 to 6.1 K depending on the orientation of the external magnetic field. This novel result in motional narrowing is analyzed analytically to be compatible with a distributionP A ofτ 0(T′, T, Δ) of half widthΔ, in reorientation times $$\tau = \bar \tau _0 \exp {E \mathord{\left/ {\vphantom {E {k T, }}} \right. \kern-\nulldelimiterspace} {k T, }}\bar \tau _0 = \smallint \tau _0 P_A dT'$$ withE=0.23 ±0.02 eV, $$\vec \tau _0 = 4.7 \times 10^{ - 13} s$$ , probably resulting from the statistical occupation of deuterium atoms among the O—−H−O bridges. Comparison with a theory of Binder definitely proves the extrinsic slowing-down and thus Halperin-Varma type character. In the range of temperatures investigated no local freeze-out has been detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01333886
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Olfactory orientation in frogs (1976)
    Springer
    Naturwissenschaften 63 (1976), S. 49-50 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768696
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Fast LEED-intensity measurements with a computer controlled television system (1976)
    Springer
    Applied physics 9 (1976), S. 247-251 
    Details
    ISSN: 1432-0630
    Keywords: LEED intensities ; Surface physics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A standard television system in combination with a processing computer is used for measurements of LEED beam intensities of a spot pattern. The video signal of the TV camera contains the intensity distribution of each spot. This can be integrated for one selected spot by the computer which also takes care of automatic background subtraction. The processing program controls the energy of the incident electron beam and follows the moving spot position. One integration of a profile and thus the measurement of one point of anI(E) curve takes 0.5 s or less. Diffracted beam currents down to 10−11 A can be detected with the present experimental set-up. The output is immediately displayed and recorded in final reduced formI/I 0.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00900612
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Säulenextraktionschromatographie mit Dithizon in o-Dichlorbenzol (1975)
    Springer
    Microchimica acta 64 (1975), S. 603-615 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Dithizone in o-dichlorobenzene as stationary phase on a chromosorb W-H. P. support is used for the enrichment and separation of metal traces. The fundamental aspects of this extraction chromatographic system are discussed and actual procedures are demonstrated with relevant illustrations. By appropriate choice of masking agents and pH value, optimal conditions for the separation of dithizone metals are developed. Nanogram amounts of zinc and cadmium are fixed on the column and afterwards stripped separately with 1-m potassium iodide solutions at various pH values. When comparing the elution efficiency of polycarboxylic acids, it was found that in weakly acidic solutions zinc and cadmium are stronger eluted by oxalate than by citrate and tartrate. In alkaline solutions, the order of elution changes to: Tartrate stronger than oxalate and citrate. Traces of zinc can be separated quantitatively from large amounts of cadmium by adding thiosulfate or iodide as selective masking agents to the test solution. By displacement extraction chromatography it is possible to achieve highly selective separations in one step. For example, the separation of mercury from large amounts of copper on columns coated with silver-dithizonate and the separation of zinc and cadmium on columns coated with lead-dithizonate are reported.
    Notes: Zusammenfassung Es wird über grundsätzliche Möglichkeiten zur säulenextraktionschromatographischen Anreicherung und Trennung von Metallspuren mit Dithizon in o-Dichlorbenzol als stationäre Phase auf Chromosorb W-H. P. berichtet und die jeweilige Arbeitstechnik an Beispielen demonstriert. Durch geschickte Wahl von Komplexierungsmittel und pH-Wert gelingt es, den Trennfaktor für die Trennungen von Dithizonmetallen mit sehr ähnlichen Komplexbildungskonstanten stark zu vergrößern. Nanogrammengen Zink und Cadmium werden zunächst auf dithizon-beladenen Säulen fixiert. Anschließend kann im pH-Bereich 4–6 Cadmium durch 1-m Kaliumjodidlösung quantitativ von der Säule gestrippt werden. Mit dem gleichen Elutionsmittel kann Zink bei pH 〉 10 von der Säule abgelöst werden. Mit 1-m Tartratlösung in 3-n Ammoniak gelingt diese Trennung in einem Schritt. Beim Vergleich der Elutionswirkung von Maskierungsreagenzien wird festgestellt, daß sich die für die Elution von Cadmium und Zink im schwach sauren Milieu geltende Reihenfolge: Oxalat stärker eluierend als Citrat und Tartrat im alkalischen Bereich, ändert; hier gilt: Tartrat stärker eluierend als Oxalat und Citrat. Durch Zusatz selektiver Maskierungsmittel zur Aufgabelösung läßt sich die Fixierung einer Komponente auf der Säule von vornherein verhindern (Matrixabtrennung). Die zweite Komponente bleibt fest gebunden und kann mit einem geeigneten Elutionsmittel abgelöst werden. So können 100 ng Zink durch Zusatz von Jodid oder Thiosulfat in schwach saurem Milieu selektiv von der 105fachen Menge Cadmium abgetrennt werden. Durch die Methode der Säulenverdrängungsextraktionschromatographie ist es möglich, in einem Arbeitsschritt hochselektive bzw. spezifische Trennungen und Anreicherungen von Metallspuren durchzuführen. Als Beispiel wird über eine Zink/Cadmium-Trennung auf bleidithizonat-beladenen Säulen berichtet. Bei Verwendung silberdithizonat-beladener Säulen gelingt mit diesem Verfahren auch die Anreicherung von Quecksilber aus einer Kupfer-Matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01225621
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Bestimmung von Kupfer und Silber in Reinstblei durch Röntgenfluoreszenzanalyse nach säulenextraktionschromatographischer Anreicherung mit Dithizon in o-Dichlorbenzol (1976)
    Springer
    Microchimica acta 65 (1976), S. 375-384 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The sample is solved in a HNO3/H2O2 solution before Cu and Ag are separated from the matrix by means of reversed phase chromatography. (Chromatographic system: Dithizone in o-Dichlorobenzene as stationary phase on a Chromosorb W-HP 80/100 mesh support). In form of [AgI4]3− and [CuI4]2−, the metal traces are concentrated on the strong basic ion exchange resin loaded-paper SERVA-SB 2 and determined by X-ray fluorescence. It is shown, that quantities down to 0,1 ppm Ag and Cu in lead can be determined with sufficient accuracy and precision, when measuring the Ag Lα1 (1) and Cu Kα1 (1) fluorescence. The determination of five reference standards leads to good correspondence of the results.
    Notes: Zusammenfassung Über ein schnelles und einfaches Verfahren zur gemeinsamen Bestimmung von Cu und Ag in Rein- und Reinstblei wurde berichtet. Nach Lösen der Probe in HNO3 und H2O2 werden Cu und Ag zugleich durch ein säulenextraktionschromatographisches Verfahren (stationäre Phase: Dithizon in o-Dichlorbenzol, Träger: Chromosorb W-HP 80/100 mesh) von der Bleimatrix abgetrennt und danach als [AgJ4]3− und [CuJ4]2− am Anionenaustauscherpapier SERVA-SB-2 angereichert. Durch Zusetzen von110mAg und64Cu zur Probe wurde der Trennvorgang untersucht. Die durch das Verfahren bedingten Verluste wurden radiometrisch bestimmt und betragen für beide Ionen etwa 2–5%. Die Endbestimmung erfolgt durch RFA. Kupfer wird durch Messen der Cu Kα1 (1)-Resonanzstrahlung (2 Θ=45,02°) bestimmt, Silber durch Messen der Ag Lα1 (1)-Fluoreszenz (2 Θ=56,76°). Da Interferenzen nur in Extremfällen auftreten, können beide Metallspuren nebeneinander bestimmt werden. Noch 0,1 ppm Silber und Kupfer im Blei können treffsicher und gut reproduzierbar bestimmt werden. An fünf Standard-Rein-und Reinstbleiproben wurden Vergleichsanalysen durchgeführt, die sehr gute Übereinstimmung zwischen gefundenen und gegebenen Analysenwerten erbrachten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01218269
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Bestimmung von Kupfer und Zink in hochreinen Wolframund Molybdänverbindungen durch Atomabsorptionsspektrometrie nach säulenextraktionschromatographischer Anreicherung mit Dithizon in o-Dichlorbenzol (1977)
    Springer
    Microchimica acta 68 (1977), S. 5-13 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Using Flame- and Flameless AAS, nanogram amounts of Cu and Zn are determined in MoO3 and WO3. The sample is dissolved in NaOH, prior to the enrichment of Cu and Zn by means of reversed phase chromatography. Depending on the AAS-technique, the trace metals are recovered in aqueous KI or MIBK. Calibration curves are prepared by using standard zinc and copper solutions with the entire relevant procedure. It is shown, that trace amounts of Cu and Zn can be determined with sufficient accuracy and precision, when high purity reference samples are analyzed. The comparison of Flame AAS and Graphite Tube shows good correspondence of the results.
    Notes: Zusammenfassung Über ein einfaches und schnelles säulenextraktionschromatographisches Verfahren zur atomabsorptionsspektrometrischen Bestimmung von Nanogramm-Mengen Kupfer und Zink in doppelt sublimiertem MoO3 und WO3 wurde berichtet. Nach Auflösen der Proben in NaOH wird die Lösung mit HCl auf pH ∼7,0 eingestellt und einer chromatographischen Trennsäule (stationäre Phase: Dithizon ino-Dichlorbenzol, Träger: Chromosorb W-HP 80/100 mesh) aufgegeben. Kupfer und Zink werden am Säulenkopf angereichert und können nach Abtrennung von der Matrix in 1–2 ml Elutionsmittel von der Säule gelöst werden. Soll die Endbestimmung durch AAS in der Flamme erfolgen, so eluiert man mit wäßriger, schwefelsaurer KJ-Lösung. Für die flammenlose atomabsorptionsspektrometrische Bestimmung von Cu und Zn im Graphitrohr werden die beiden Metallspuren mit Methylisobutylketon von der Säule gewaschen. Die extraktionschromatographische Anreicherung auf der Säule wurde radiometrisch mit65Zn und64Cu untersucht. Dabei zeigte sich, daß Zink im Gegensatz zum Cu nur in Gegenwart von Oxalat quantitativ von Wolfram abgetrennt werden kann. Zur Feststellung des mit der beschriebenen Methode der Bestimmung von Cu und Zn erfaßbaren Bereiches wurden Eichkurven erstellt und damit der Gehalt doppelt sublimierter MoO3- und WO3-Proben bestimmt. MoO3-Proben wurden nach Dotieren mit Zn und Cu nach beiden beschriebenen AAS-Verfahren analysiert. Die Übereinstimmung zwischen gefundenen und gegebenen Analysenwerten ist zufriedenstellend.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01196306
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    SIMS and flash desorption studies of nickel oxygen interaction (1978)
    Springer
    Applied physics 16 (1978), S. 367-373 
    Details
    ISSN: 1432-0630
    Keywords: 79.20 ; 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract O2 exposure of polycrystalline nickel at 300 K results in characteristics changes of secondary ion emission. These can be described by a model which is in good agreement with corresponding LEED, AES, XPS, and ΔΦ results of other authors. According to this model, oxygen can be bonded on Ni in at least five different phases: 1) chemisorption, indicated by a rapid increase of Ni+, Ni 2 + , and Ni2O+ (≦5 L); 2) a rearranged chemisorption layer, characterized by a drastic decrease of Ni+, Ni 2 + , and Ni2O+ (5–15 L); 3) nickel oxide (NiO) responsible for a strong NiO−- and NiO 2 − -emission (≦40 L); 4) oxygen on top of this NiO layer, producing a final increase of Ni+ and NiO+ and a O2-flash signal at 400 K (〉40 L); 5) bulk dissolved oxygen in thermal equilibrium with a chemisorption layer (after several exposure/heating cycles). During ion bombardment of a 100 L O2 exposed Ni surface these different binding states occur in a reversed order of succession. O2-flash signals at 400 and 1100 K, related to drastic changes in secondary ion emission at 400, 700, and 1100 K, reflect the disappearance of various oxygen binding states. The exchange between different oxygen phases was studied by16O2/18O2 isotope experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00885861
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The structure of theL 2,3 VV-auger line of silicon and silicon compounds (1977)
    Springer
    Applied physics 14 (1977), S. 283-287 
    Details
    ISSN: 1432-0630
    Keywords: 79.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract TheL 2,3 VV Auger transitions of Si, SiO2, and SiC have been measured and compared with the self-fold electron density of states. The data indicate that Auger matrix effects must be included to explain the structure of the Auger lines. A comparison with soft X-ray measurements of Wiech shows, that the measured Auger line shape is nearly identical with the self-foldK β emission band. The selection rules for X-ray emission lead then to the conclusion that mostlyp-like valence electrons are involved in the Auger transition. This result indicates the relative importance ofs andp states in Auger transitions which is in accordance with theoretical calculations of Feibelman et al.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00882733
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Some aspects of auger electron spectra of 3d transition metal oxides (1977)
    Springer
    Applied physics 13 (1977), S. 43-46 
    Details
    ISSN: 1432-0630
    Keywords: 79.20 ; 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Auger electron spectra of the transition metals Cr, Mn, Fe, Co and Ni as well as their oxides have been investigated in the energy range between 0–100 eV. In each case of the clean metal surface the observed spectrum consists essentially of one Auger line identified asM 2,3 VV transition. After oxidation a line doublet is observed revealing two transitions instead of one. Additional new Auger peaks appear in the low energy range between 0–30 eV. The “splitting” of the Auger line can be explained as resulting from aM 2,3 V dVd and aM 2,3 V pVp transition. The latter is characteristic for the compound and can in a simple way be interpreted as a cross transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00890718
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...