Aufbau und Zunderverhalten von Niob-Bor-Silicium-Legierungen

Zusammenfassung Der Aufbau des Dreistoffes Niob-Bor-Silicium wird bei 1600° C mit Hilfe röntgenographischer und mikroskopischer Methoden ermittelt. Die T 2-Phase sowie die ternäre D 8₈-Phase besitzen einen ausgedehnten homogenen Bereich. Während Silicium in T 2 durch Bor bis annähernd Nb₅SiB₂ substituiert wird, besteht beim D 8₈-Typ eine Gitterauffüllung gemäß Nb₅Si₃B. Oxydationsversuche im Bereich von 400 bis 1200° C zeigen vor allem die Selektivität, indem Nb–Mk bzw. die Nb-Boride bevorzugt in Pentoxyd übergehen. Silicium übt einen stabilisierenden Einfluß auch auf das Bestehen von -Nb₂O₅ aus. -Nb₂O₅ tritt als Mischphase mit Anionendefekt auf, wodurch die sogenannte scharfe und diffuse Form erklärt wird. Die Umwandlungstemperatur - wird teilweise erheblich oberhalb der vonGoldschmidt angegebenen beobachtet. Die -Form wird als M-Modifikation nachBrauer identifiziert und relativ häufig nachgewiesen. Die -Form erweist sich alsBrauersche H-Modifikation und entsteht offensichtlich stufenweise (fast kontinuierlich) aus -Nb-Oxyd. Auf die Anionendefekt-Bildung wird nachdrücklich hingewiesen.Mit 3 Abbildungen     

Structurization and Optical Activity in Cellulose Triacetate Modified with Trifluoroacetic Acid Vapor

Structurization in cellulose triacetate modified with trifluoroacetic acid vapor and its effect on the optical activity are studied.     

2,3-Diphenylthiazolo[3,2-a]pyrimidinium salts

The corresponding 2,3-diphenyl[3,2-a]pyrimidinium salts were obtained by the condensation of 4,5-diphenyl-2-aminothiazole perchlorate with -diketones, -chlorovinyl ketones, -chlorovinyl aldehydes, and 1,1,3,3-tetraethoxypropane. The PMR spectra were used to prove the structures of the compounds obtained, particularly to select the structures of the isomeric salts obtained in the condensation with unsymmetrical -diketones, -chlorovinyl ketones, and -chlorovinyl aldehydes. As a rule, the latter give one isomer — the -unsubstituted (relative to the bridge nitrogen atom) derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 629–631, May, 1972.     

Thermal evolution of ferromagnetic metallic glasses

A traditional TG apparatus was modified by placing two permanent magnets producing a controlled magnetic field (TG(M): Magneto Thermogravimetry). This technique proved to be useful to study both structural relaxation and crystallisation of ferromagnetic metallic glasses. Results obtained for the amorphous alloys Fe₄₀Ni₄₀P₁₄B₆ and Fe_62.5Co₆Ni_7.5Zr₆Nb₂Cu₁B₁₅, are reported in this paper. Structural relaxation can be evaluated by measuring changes in Curie temperature induced by thermal treatments. Crystallisation in TG(M) is detected through a change in the measured apparent mass (difference between the sample mass and magnetic force driving it upward). These results were confirmed by DSC analysis. Whether the obtained crystalline phase is ferromagnetic, it can be identified through its Curie temperature, measured by TG(M). In fact the value of 770°C measured as Curie temperature of crystallised Fe_62.5Co₆Ni_7.5Zr₆Nb₂Cu₁B₁₅led to conclude that the only ferromagnetic crystalline phase is a-Fe. These hypothesis was confirmed by XRD analysis, showing that the first crystallisation yields to a-Fe nanocrystals. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reaction of 1,5-diaryl-3-hydroxy-4-methylsulfonyl-3-pyrrolin-2-ones with urea,hydrazine, ethylenediamine,and <Emphasis Type="Italic">o</Emphasis>-phenylenediamine

With urea 1,5-diaryl-3-hydroxy-4-methylsulfonyl-3-pyrrolin-2-ones form the 3-amino derivatives of pyrrolones. In reactions with hydrazine hydrate and ethylenediamine the corresponding salts are formed. With ethylenediamine at 180–185°C the double salt of 3-hydroxy-4-methylsulfonyl-1,5-diphenyl-3-pyrrolin-2-one forms N,N′-di(4-methylsulfonyl-1,5-diphenyl-3-pyrrolin-2-on-3-yl)-ethylenediamine. The reaction with o-phenylenediamine gives 2,3-diaryl-4-methylsulfonylpyrrolo-[2,3-b]quinoxalines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1631–1636, November, 2007.     

Comparison of procedures for correction of matrix interferences in the multi-element analysis of soils by ICP-AES with a CCD detection system

Three procedures, matrix matching, plasma optimisation and single-point standard-addition, have been evaluated to ascertain the best procedure for simultaneous multi-element analysis of industrial soils by ICP-AES with CCD detection. A standard reference material, CRM143 from the Bureau Communautaire de Réference (BCR), has been analysed for Cd, Cr, Cu, Mn, Ni and Pb using the three different matrix interference correction procedures. All three procedures give comparable results which are in good agreement with the BCR values, except for Cr. The single-point standard addition procedure was chosen, on the basis of economy and ease of implementation, to correct for matrix interferences in the determination of Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sn and V in soil samples collected from an industrial site in England. Concentrations of some of the elements were found to vary greatly with sampling depth. For example, the concentration of Mn, determined using the atomic line at 279.920 nm, increased from 426 ± 3 g/g at a depth of 18–28 cm to 5996 ± 144 g/g at 60–85 cm.     

Structure of the products of the cyclization in acetic anhydride of β-(2-carboxy-5-chlorophenylamino) propionic acid and its nitrile

-(2-Carboxy-5-chlorophenylamino)propionic acid cyclizes in acetic anhydride to form 4-chloro-2-(2,4-dioxopiperidino)benzoic acid, which subsequently undergoes conversion into its lactone. Under the same conditions, -[acetyl(2-carboxy-5-chlorophenyl)amino]-propionitrile forms 7-chloro-1--cyanoethyl-1,2,3,4-tetrahydroquinoline-2,4-dione. The structures of the compounds obtained were confirmed by their IR, UV, and PMR spectra. An evaluation of the stability of the ketonic and enolic forms of the compounds obtained on the basis of calculations by Hückel's method has been made.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 7, pp. 879–884, July, 1970.     

The role of dimeric molecules of metalloporphyrins in phototransfer of an electron through liposome membranes

Conclusions Charge separation in solutions of liposomes sensitized by MP at low temperatures and apparently also at 20°C takes place according to a mechanism of two-quantum photoionization of dimeric molecules of the metalloporphyrins.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 277–282, February, 1985.