Le système Ba2Fe2O5BaZnO2. I. Mise en évidence de trois nouvelles phases

In order to obtain phases with a high deficiency of oxygen, iron is progressively substituted by zinc in Ba₂Fe₂O₅ at 900–1000°C. For 0.05 < x < 0.40 ($\text{x =}\text{Zn}\text{Fe}\text{+}\text{Zn}$), the long-range order between tetrahedra and octahedra of the brownmillerite is destroyed and the cell is perovskite type with up to 23% oxygen vacancies. For x = 0.5 there is a new superlattice and an orthorhombic compound Ba₄Fe₂Zn₂O₉. For 0.7 < x < 0.9 a new cubic phase is formed which is related to BaZnO₂.     

LASER-LIGHT INDUCED CHROMOSOME ABERRATIONS IN CHINESE HAMSTER CELLS

Wild-type Chinese hamster cells CHO Kl and their radiosensitive mutant xrs5 were irradiated at 308 nm, using light pulses of a XeCl excimer laser with total energy fluences of 0.1 kj/m² to 4.08 kj/m². Chromosome-type and chromatid-type chromosome aberrations have been observed at pulse irradiances of 2.5 × 10⁷ W/m² and 1.7 × 10⁸ W/m², indicating that in mammalian cells DNA double-strand breaks occur already in this irradiance range. The results obtained with laser irradiation are compared with X-ray irradiation.     

der Nachweis von Flavonen und ihrer Abbauprodukte mit stabilen Diazoniumsalzen durch Tüpfelreaktionen

Zusammenfassung Unter Verwendung von neun stabilen Diazoniumsalzen wird gezeigt, daß mit Hilfe des Tüpfeltestes das Erkennen von Di- und Trihydroxybenzolen und das von aromatischen Hydroxysäuren in Mikrogrammengen durch charakteristische Farbstoffbildung möglich ist. Durch die hohe Empfindlichkeit des Nachweises von Hydroxybenzolen bzw. Hydroxy benzolcarbonsäuren ist es möglich, diese bei der Alkalischmelze der Hydroxyphenyl-benzo--pyron-Derivate auftretenden Spaltprodukte im Tüpfeltest zu identifizieren.Durch Anwendung des Tüpfeltestes wird das Verhalten von 28 Flavonen nach dem Umsetzen mit drei stabilen Diazoniumsalzen, diazotiertem 4-Amino-3,6-dimethoxy-4-nitroazobenzol, diazotiertem 1-Amino-4-benzoylamido-2, 5-diäthoxybenzol und tetraazotiertem Di-o-anisidin, und die Erfassungsgrenze im Tages- und im UV-Licht festgestellt. Auch mit Hilfe des Tüpfeltestes lassen sich bei Verwendung von diazotiertem 4-Amino-3,6-dimethoxy-4-nitroazobenzol als Reagens die Flavonaglykone von den Flavonglykosiden unterscheiden und in gleicher Weise wie im Papierchromatogramm entstehen gelbe oder blaue Farbstoffe je nach der Konstitution der Hydroxyphenyl-benzo--pyron-Derivate.

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Summary By means of nine stabilized diazonium salts it was shown that with the aid of the spot test it is possible to detect microgram quantities of di- and trihydroxybenzenes and of aromatic hydroxy acids through the formation of characteristic dyes. Because of the great sensitivity of the tests for hydroxybenzenes and hydroxybenzene carboxylic acids, it is possible to detect them by a spot test in the fission products of the alkali fusion of hydroxyphenylbenzo--pyrone derivatives.By means of the spot test a study was made of the behavior of 28 flavones after reaction with 3 stable diazonium salts, and with diazotized 4-amino-3, 6-dimethoxy-4-nitro azobenzene, diazotized 1-amino-4-benzoylamino-2,5-diethyloxybenzene, and tetraazotized di-o-anisidine. The limits of identifica-tion were determined in daylight and in ultraviolet. Likewise, with the aid of the spot test, and using diazotized 4-amino-3,5-dimethoxy-4-nitroazobenzene as reagent, it is possible to distinguish the flavone glycosides and the flavon-aglycones; in the same manner as in the paper chromatogram, blue or yellow dyestuffs are produced, depending on the constitution of the hydroxyphenyl-benzo--pyrone derivatives.

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Résumé L'auteur montre qu'il est possible de caractériser à l'échelle du microgramme les di et trihydroxybenzènes et les acides aromatiques hydroxylés par formation de matières colorantes caractéristiques lors d'essais à la touche effectués en employant neuf sels stables de diazonium.La sensibilité de l'identification des hydroxybenzènes et des acides hydroxybenzène carboxyliques est si élevée qu'elle permet par un essai à la touche de mettre en évidence l'apparition de ces composés comme produits de dégradation lors de la fusion alcaline de dérivés de l'hydroxyphényl-benzo--pyrone.On a déterminé par essai à la touche le comportement de 28 flavones lors de leurs réactions sur les 3 sels stables de diazonium suivants: le 4-amino-3, 6-diméthoxy-4-nitroazobenzène diazoté; le 1-amino-4-benzoylamido-2,5-diéthoxybenzène diazoté et la diorthoanisidine tétraazotée; on a établi simultanément les limites de sensibilité correspondantes à la lumière du jour et à la lumière ultraviolette. Les essais à la touche ont également permis la différenciation des flavonoaglucones des flavonoglucosides en employant le 4-amino-3,6-dimethoxy-4-nitroazobenzène diazoté comme réactif; de même qu'en chromatographie sur papier, il se forme une matière colorante soit jaune, soit bleue suivant la constitution des dérivés de l'hydroxyphényl-benzo--pyrone.

     

Charge distribution and local structure and speciation in the UO2+x and PuO2+x binary oxides for x?0.25

The local structure and chemical speciation of the mixed valence, fluorite-based oxides UO_2+x (0.00?x?0.20) and PuO_2+x/PuO_2+x−y(OH)_2y·zH₂O have been determined by U/Pu L_III XAFS spectroscopy. The U spectra indicate (1) that the O atoms are incorporated as oxo groups at short (1.75 Å) U-O distances consistent with U(VI) concomitant with a large range of U displacements that reduce the apparent number of U neighbors and (2) that the UO₂ fraction remains intact implying that these O defects interact to form clusters and give the heterogeneous structure consistent with the diffraction patterns. The PuO_2+x system, which does not show a separate phase at its x=0.25 endpoint, also displays (1) oxo groups at longer 1.9 Å distances consistent with Pu(V+δ), (2) a multisite Pu-O distribution even when x is close to zero indicative of the formation of stable species with H₂O and its hydrolysis products with O²⁻, and (3) a highly disordered, spectroscopically invisible Pu-Pu component. The structure and bonding in AnO_2+x are therefore more complicated than have previously been assumed and show both similarities but also distinct differences among the different elements.     

Quadrupole moments of radium isotopes from the 7p 2 P 3/2 hyperfine structure in Ra II

The hyperfine structure and isotope shift of^221–226Ra and^212,214Ra have been measured in the ionic (Ra II) transition 7s ² S _1/2–7p ² P _3/2 (λ=381.4 nm). The method of on-line collinear fast-beam laser spectroscopy has been applied using frequency-doubling of cw dye laser radiation in an external ring cavity. The magnetic hyperfine fields are compared with semi-empirical and ab initio calculations. The analysis of the quadrupole splitting by the same method yields the following, improved values of spectroscopic quadrupole moments:Q _s (²²¹Ra)=1.978(7)b,Q _s (²²³Ra)=1.254(3)b and the reanalyzed valuesQ _s (²⁰⁹Ra)=0.40(2)b,Q _s (²¹¹Ra)=0.48(2)b,Q _s (²²⁷Ra)=1.58(3)b,Q _s (²²⁹Ra)=3.09(4)b with an additional scaling uncertainty of ±5%. Furthermore, theJ-dependence of the isotope shift is analyzed in both Ra II transitions connecting the 7s ² S _1/2 ground state with the first excited doublet 7p ² P _1/2 and 7p ² P _3/2.     

Dissolution of plutonium(IV) hydroxide by desferrioxamine siderophores and simple organic chelators

Plutonium is thought to exist mostly as low soluble plutonium(IV) species in the environment and, therefore, has low potential of becoming mobile. Due to their prevalence and high solution stability constants for Pu(IV), microbial siderophores could significantly affect plutonium solubility and mobility. In this study, the ability of trihydroxamate desferrioxamine siderophores to solubilize Pu(IV) solids was investigated. Both desferrioxamine B and E (DFB and DFE) are far less effective at solubilizing amorphous Pu(IV) hydroxide in neutral solution than are simple chelators, such as EDTA, citrate, and tiron, despite the fact that these chelators have smaller solution stability constants for Pu(IV) than do DFE and DFB. Positively charged, linear DFB is less effective than the neutral cyclic DFE. Hydroxamate siderophores may, in fact, passivate Pu(IV) hydroxide surfaces, thereby inhibiting solubilization by other chelators. PuO(2) solubilization under these conditions is far slower than that of Pu(IV) hydroxide.     

Le syste`me BaFeO2,50BaZnO2. II. Conductivite´mixte et autres proprietes physiques

La phase α de type perovskiteBaFe_1?xZn_xO_2,5?x/2 (0.05 < x < 0,40) pre´sente un ferrimagne´tisme faible pourx < 0,25, avecT_c de l'ordre de 470°C, puis paramagne´tique (au-dessus de 77 K) pourx > 0,25, ce qui traduit la destruction progressive de l'ordre antiferromagne´tique observe´dans BaFeO_2.5. Les phases β (Ba_4Fe2Zn₂O₉) et γ (BaZn_1?yFe_yO_2+y/2) sont en accord avec une forte perturbation du site octae´drique de la perovskite. La conductivite´est asseze´leve´e, de caracte`re mixte, avec une re´partition ionique-e´lectronique qui de´pend des conditions de synthe`se, et de la tempe´rature compte tenu dese´nergies d'activation diffe´rentes. Le coefficient de diffusion de l'oxyge`ne qui s'en de´duit este´leve´, mais le nombre de porteurs est restreint par la formation de paires de lacunes d'oxyge`ne tendant vers la coordinence 4 du fer.     

Eine neue organische Borverbindung als analytisches Reagens

Ohne ZusammenfassungII. Mitteilung über Tetraphenyl-diboroxyd, gleichzeitig auch V. Mitteilung über Mavone und. Flavonole: I. Mitt. diese Z. 139, 96 (1953). -II. Mitt. Naturwissenschaften 40, 411 (1953). — III. Mitt. Arch. Pharmaz. Ber. dtsch. pharmaz. Ges. 286/58, 486 (1953). — IV. Mitt. Arch. Pharmaz Ber. dtsch. pharmaz. Ges. 287/59, 70 (1954).