Darstellung und thermische Zersetzung von Lithiumcyanuraten Eine einfache Methode zur Gewinnung von wasserfreiem Lithiumcyanat

Zusammenfassung Die Darstellung von Mono-, Di- und Tri-Lithiumcyanurat durch Umsetzung von Cyanursäure mit LiOH bzw. Li₂CO₃ in hochsiedenden Alkoholen und durch lösungsmittelfreie Festkörperreaktion wird beschrieben. Die Festkörperreaktionen werden mit Hilfe thermoanalytischer Methoden untersucht. Die Reaktion mit LiOH erfolgt in zwei Schritten und ergibt bei 400°C. Trilithium-cyanurat. Unter denselben Bedingungen wird mit Li₂CO₃ nur Dilithium-cyanurat gebildet. Die Thermolyse von Trilithium-cyanurat bei 550°C liefert in hoher Ausbeute Lithiumcyanat und stellt somit eine einfache Methode zur Darstellung dieser Verbindung in wasserfreier Form dar.

---

Formation and thermolysis of lithium cyanurates (a simple preparation of anhydrous lithium cyanate)

The formation of mono-, di- and tri-lithium cyanurate by reaction of LiOH or Li₂CO₃ with cyanuric acid has been investigated as a solid state reaction and by using high boiling alcohols as reaction medium. For investigating the solid state reactions thermoanalytical methods were used. The reaction with LiOH proceeds in two steps yielding trilithium cyanurate at 400°C. Under the same conditions only dilithium cyanurate is formed by reaction with Li₂CO₃. Lithium cyanate is obtained in high yields by thermolysis of trilithium cyanurate at 550°C. This procedure is therefore a simple method in synthesizing pure anhydrous lithium cyanate.

---

---

Mit 3 Abbildungen

---

Herrn Univ.-Prof. Dr.O. Kratky zum 70. Geburtstag gewidmet.     

ANTIVIRAL ACTIVITY OF MEROCYANINE 540

Abstract Simultaneous exposure to the lipophilic dye merocyanine 540 (MC 540) and white light inactivates several enveloped viruses. The same treatment appears to have little or no effect on pluripotent hematopoietic stem cells, mature red cells, and mature leukocytes. At least some components of the clotting system are spared, too. The molecular basis of the virucidal effect of MC 540 and light is not yet completely understood. Based on what is known about the interactions of MC 540 with cells and artificial membranes, it seems likely that MC 540 binds to and damages the viral envelope. MC 540-mediated photosensitization may have implications for the sterilization of bone marrow and blood products, the preparation of vaccines, and selected areas of antiviral therapy.     

Bestimmung von Iridiumspuren mit Dithizon mittels substöchiometrischer Isotopenverdünnungsanalyse

Iridium(III or IV) reacts with dithizone on heating at pH 6 to form a 1∶2 complex, which can be concentrated by extraction into chloroform. Based on this reaction, a reproducible, selective determination of iridium (1 ppb) is achieved by means of substoichiometric isotope dilution analysis based on¹⁹²Ir.     

(Z)-3-p-tolylsulfinylacrylonitrile as a chiral dienophile: diels-alder reactions with furan and acyclic dienes

The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles.     

Narrow band quantitative and multivariate electroencephalogram analysis of peri-adolescent period

ABSTRACT: BACKGROUND: The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). RESULTS: The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0--20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. CONCLUSIONS: The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages.     

Tunable-chirp pulse compression in quasi-phase-matched second-harmonic generation

We demonstrate continuously tunable compensation of linear chirp on a first-harmonic pump pulse to produce a near-transform-limited second-harmonic output pulse through the use of a chirped, fanned, periodically poled lithium niobate quasi-phase-matching grating. Compensation of positive and negative chirps is possible through reversal of device orientation. The device is simple and monolithic and can be applied to compensation of a higher-order phase with minor modification.     

Static and dynamic elastic moduli in the Thomas Fermi model

If one uses perturbation theory for the electronic contributions, the elastic moduli obtained from static deformations and from lattice vibrations do not agree in the same order [1, 2]. The reason for this is shown by employing a very simple lattice model: Thomas-Fermi-Theory for the electrons, Coulomb interaction and additive central force interaction between ions.     

Balance of mass, momentum, and energy in splintering central collisions for 40Ar up to 115 MeV /Nucleon

For central collisions of (17-115)A MeV 40Ar+Cu, Ag, Au, an overall balance is determined for the average mass, energy, and longitudinal momentum. Light charged particles and fragments are separated into forward-focused and isotropic components in the frame of the heaviest fragment. Energy removal by the isotropic component reaches 1-2 GeV. For such high deposition energies, statistical multifragmentation models predict much more extensive nuclear disassembly than is observed.