Room-temperature ferromagnetism in pure ZnO nanoflowers

ZnO nanoflowers are synthesized by hydrothermal method. The morphology of ZnO is captured by SEM, TEM and HRTEM, which is composed of closely packed nanorods of about 100 nm in diameter and 1 μm in length. The ZFC/FC curves show superparamagnetic features. The abnormal increase in magnetization curves below 14 K comes from the isolated vacancy clusters with no interaction. The magnetic hysteresis at 300 K displays saturation state and confirms room-temperature ferromagnetism. While the magnetic hysteresis at 5 K shows nonsaturation state due to the enhanced effects of vacancy clusters. The O 1s XPS results can be fitted to three Gaussian peaks. The existence of medium-binding energy located at 531.16 eV confirms the deficiency of O ions at the surface of ZnO nanoflowers.     

Complete suppression of metastable phase and significant enhancement of magnetic properties of B-rich PrFeB nanocomposites prepared by devitrifying amorphous ribbons

The effect of refractory element addition on phase transformation, crystallization behavior and magnetic properties of Pr_8.5Fe_81.5B₁₀ (addition-free) and Pr_8.5Fe_81.5M₂B₁₀ (M=V, Cr, Nb, Zr, Ti) ribbons has been investigated. The annealed addition-free ribbon as well as the samples with V or Cr additions are mainly composed of the metastable Pr₂Fe₂₃B₃ phase, whereas annealed ribbons with Nb, Zr or Ti additions primarily consist of Pr₂Fe₁₄B and a minor amount of Fe₃B/boride. The complete suppression of the metastable Pr₂Fe₂₃B₃ phase due to Nb, Zr or Ti additions leads to a significant enhancement of the magnetic properties. For example, the remanence, the coercivity and the energy product are remarkably increased from 2.5 kG, 0.4 kOe and 0.2 MG Oe for the addition-free material to 9.2 kG, 4.7 kOe and 7.6 MG Oe for the specimens with Nb addition. The successful elimination of the metastable Pr₂Fe₂₃B₃ phase is believed to profit from two factors: (a) Nb, Zr or Ti atoms substitute the Pr site, comparatively increase the Pr content, and thus inhibit the nucleation of Pr-lean Pr₂Fe₂₃B₃ phases, and (b) the formation of Nb, Zr, or Ti borides consumes some part of B, which hinders the generation of the B-rich Pr₂Fe₂₃B₃ phase.     

Eine neue Methode zur Bestimmung von Aluminiumoxyd in Aluminiumlegierungen

Zusammenfassung Wir haben eingangs von der qualitätsvermindernden Wirkung von Oxydeinschlüssen in Aluminiumlegierungen gesprochen und die bisher gebräuchlichen Bestimmungsmethoden, d. h. Erhitzen im HCl-, bezw. Cl₂-Strom näher betrachtet. Dabei zeigten sich in der Schwierigkeit, übereinstimmende Werte zu erzielen, und der Kompliziertheit der Apparatur beträchtliche Nachteile. Diesen trocknen Methoden wurde die neue Oxydbestimmungsmethode auf nassem Weg gegenübergestellt, die auf der Trennung der Metalle von Aluminiumoxyd und Silicium durch Kupferchloridlösung beruht. D e Abweichung der untereinander in guter übereinstimmung stehenden Resultate von den auf trocknem Wege erhaltenen wurde auf verschiedene Modifikationen des Aluminiumoxyds zurückgeführt.     

Die „Unbenetzbarkeit“ von Böden und feinen Pulvern überhaupt

Ohne Zusammenfassung     

Die Schichtenbildung,zumal von Boden- und Tontrübungen,ihre Erklärung und ihre Heranziehung zur landwirtschaftlichen Bodenuntersuchung

Ohne Zusammenfassung     

Misincorporation of alkylated amino acids into hemoglobin--a possible source of background alkylations

Misincorporation of 2-hydroxyethylated amino acids into hemoglobin during de novo synthesis was studied by injecting mice with radiolabelled N-(2-hydroxyethyl)valine, S-(2-hydroxyethyl)cystine or N tau-(2-hydroxyethyl)histidine. The results showed that S-(2-hydroxyethyl)cysteine and N tau-(2-hydroxyethyl)histidine were misincorporated, whereas N-(2-hydroxyethyl)valine was not. Monitoring of in vivo doses of hydroxyethylating agents by determination of N-(2-hydroxyethyl)valine was free of the disturbing influence of such misincorporation.     

Ca3N2 and Mg3N2: unpredicted high-pressure behavior of binary nitrides

High-pressure synthesis allows both fundamental and materials science research to gain unprecedented insight into the inner nature of materials properties at extreme environment conditions. Here, we report on the high-pressure synthesis and characterization of γ-Ca(3)N(2) and the high-pressure behavior of Mg(3)N(2). Investigation of M(3)N(2) (M = Ca, Mg) at high-pressure has been quite challenging due to the high reactivity of these compounds. Ex situ experiments have been performed using a multianvil press at pressures from 8 to 18 GPa (1000-1200 °C). Additional in situ experiments from 0 to 6 GPa (at RT) at the multianvil press MAX 80 (HASYLAB, Beamline F.2.1, Hamburg) have been carried out. The new cubic high-pressure phase γ-Ca(3)N(2) with anti-Th(3)P(4) defect structure exhibits a significant increase in coordination numbers compared to α-Ca(3)N(2). Contrary, Mg(3)N(2) shows decomposition starting at surprisingly low pressures, thereby acting as a precursor for Mg nanoparticle formation with bcc structure. Soft X-ray spectroscopy in conjunction with first principles DFT calculations have been used to explore the electronic structure and show that γ-Ca(3)N(2) is a semiconductor with inherent nitrogen vacancies.