Determination of bismuth in geological materials by automated hydride generation and electrothermal atomic absorption spectrometry

The rapid and precise determination of bismuth (>5 μg kg^?1 in geological materials is described. The sample is decomposed with a HClO₄/HNO₃/HF mixture; interferences are eliminated by addition of aluminium chloride, ascorbic acid and thiourea. Bismuth hydride is introduced into a quartz cell atomizer.     

Density and surface tension of molten calcium fluoride

The density and the surface tension of molten calcium fluoride have been measured in the temperature range from 1690 to 1790 K by an improved Archimedian method and a ring depressing technique (J. Crystal Growth 187 (1998) 391), respectively. The ring depressing technique was demonstrated as an effective technique to measure the surface tension in comparison with the conventional ring pulling technique. The density varied with the temperature change corresponding to a linear relationship: ρ=3.767−6.94×10⁻⁴T (K). The density of the CaF₂ melt at the melting point is 2.594 g/cm³, which is equal to the result obtained by Shiraishi and Watanabe (Bull. Res. Inst. Miner. Dressing Metal, Tohoku Univ. 34 (1978) 1), but the temperature coefficient of the density is different from the results obtained by other investigators. The thermal expansion coefficient of calcium fluoride melt linearly increases with temperature heating. The surface tension of molten calcium fluoride indicates a negative linear relationship as a function of the melt temperature: γ(T)=442.4−0.0816×T(K) (mN/m). The surface tension measured using the ring depressing technique is larger than those results obtained by other techniques.     

Development of Rapid and Facile Solid-Phase Synthesis of PROTACs via a Variety of Binding Styles

Optimizing linker design is important for ensuring efficient degradation activity of proteolysis-targeting chimeras (PROTACs). Therefore, developing a straightforward synthetic approach that combines the protein-of-interest ligand (POI ligand) and the ligand for E3 ubiquitin ligase (E3 ligand) in various binding styles through a linker is essential for rapid PROTAC syntheses. Herein, a solid-phase approach for convenient PROTAC synthesis is presented. We designed azide intermediates with different linker lengths to which the E3 ligand, pomalidomide, is attached and performed facile PROTACs synthesis by forming triazole, amide, and urea bonds from the intermediates.     

Charge-ordered state in single-crystalline CaFeO3 thin film studied by x-ray anomalous diffraction

X-ray anomalous diffraction, together with a band-structure calculation, was employed to obtain a quantitative understanding of the charge-ordering state in a single-crystalline CaFeO3 thin film. The experimental result shows a characteristic energy dispersion of the nearly inhibited reflection at 150 K, implying Fe atoms split into two distinct states. The energy dispersion is in good agreement with the calculated spectrum based on the LDA+U scheme. The calculation also reveals an electronic structure of the system where holes in the oxygen orbital surround one of the distinct Fe atoms, in spite of the total electron number in both Fe atoms remaining unchanged.     

Angle-resolved photoemission spectroscopy of the antiferromagnetic superconductor Nd1.87Ce0.13CuO4: anisotropic spin-correlation gap, pseudogap, and the induced quasiparticle mass enhancement

We performed high-resolution angle-resolved photoemission spectroscopy on Nd1.87Ce0.13CuO4, which is located at the boundary of the antiferromagnetic (AF) and the superconducting phase. We observed that the quasiparticle (QP) effective mass around (pi,0) is strongly enhanced due to the opening of the AF gap. The QP mass and the AF gap are found to be anisotropic, with the largest value near the intersecting point of the Fermi surface and the AF zone boundary. In addition, we observed that the QP peak disappears around the Néel temperature (TN) while the AF pseudogap is gradually filled up at much higher temperatures, possibly due to the short-range AF correlation.     

Synthesis of high transition temperature superconducting Y-Ba-Cu-Ofilms by radio-frequency plasma flash evaporation

The authors have successfully developed a novel process for the deposition of multicomponent systems, namely radio-frequency (RF) plasma flash evaporation, in which powder mixtures of constituents are continuously injected into a RF plasma and are coevaporated and codeposited onto a substrate. The Y-Ba-Cu-O films prepared by this method showed excellent superconducting properties without postannealing; a deposition rate above several hundred nm/min was achieved. The film deposited on a MgO (100) substrate at 700°C reveals c-axis-oriented, polycrystalline orthorhombic oxygen-deficient perovskite showing a superconducting transition temperature of 87 K and a critical current density on the order of 1×10⁶ A/cm² at 77 K estimated from the magnetization. The conditions of plasmas during the deposition were measured by optical emission spectroscopy