Search

The structures of melt-spun, and subsequently annealed, Zr[sub 70]Pd[sub 30] alloys, which form a nanosized icosahedral quasicrystalline phase during the primary crystallization of the amorphous phase, have been investigated by means of electron-diffraction pair-distribution-function (PDF) analysis. The PDF analysis for this alloy was performed by precise measurements of elastic halo-electron-diffraction intensities. Possible structure models for as-quenched and annealed amorphous structures were constructed with the help of reverse Monte Carlo simulations. In order to obtain the local atomic structures, the Voronoi-polyhedra analysis was performed. A considerable number of icosahedral clusters with Zr atoms in the center are present in the simulated structure of the as-quenched state, and the number of the clusters increases by annealing. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Compositional analyses were performed on a δ-Sc4Zr3O12 oxide sample following irradiation with 300keV Kr++ ions to a fluence of 3×1020 Kr/m2 at cryogenic temperature (100K). Energy-dispersive X-ray spectroscopy (EDXS), Rutherford backscattering spectrometry (RBS) and depth profile X-ray photoelectron spectroscopy (XPS) analyses revealed that the cation sublattice in the near-surface region of the irradiated sample consists of at least 40% Zr. This is an unexpected result because this region has an irradiation-induced crystal structure known as bixbyite (C-rare-earth), which is a different phase than the unirradiated material and is a phase that normally does not accommodate large quantities of a tetravalent species such as Zr4+. To our knowledge, this is by far the largest concentration of Zr ever observed in a Sc2O3–ZrO2 bixbyite compound. The radiation-induced transformation of δ-Sc4Zr3O12 into a bixbyite-structured phase is also discussed in relation to the Sc2O3–ZrO2 phase diagram. [Copyright &y& Elsevier]

The effect of the iron addition on the glass-forming ability (GFA) of Nd60Al10Ni10Cu20-xFex (x=0, 2, 4) alloys has been investigated with respect to the glass transition and crystallization kinetics. The magnetic property of the as-cast samples varies from paramagnetic to ferromagnetic by partial substitution of Fe for Cu, indicating that the substitution can induce the formation of metastable phase (or cluster) and thus decreases the GFA of the alloys. The dependence of the glass transition on the heating rate was analyzed in terms of the Vogel–Fulcher–Tamman (VFT) equation. The glass-forming ability of these alloys is discussed based on the composition-dependent melting behaviour, the reduced glass transition temperature, and the fragility parameter. It is shown that substitution of Fe for Cu does not improve the glass-forming ability of the alloys and lowers the thermal stability of the alloys. The studied alloys are found to be rather strong glass formers and possess relatively low glass transition temperature. [Copyright &y& Elsevier]

Abstract: Crystallization behavior of Pd42.5 Ni7.5 Cu30 P20 and Pd40 Ni40 P20 (number indicate at.%) bulk metallic glasses under ultrasonic (US) vibrations of sub/low-MHz frequencies has been systematically investigated. It was found that, when the glassy sample was subjected to the US vibrations for a long duration, the crystallization occurred even (near) below the glass transition temperature . The microstructural features of the US-accelerated crystalline phases are presented, and the mechanism of the US-accelerated crystallization is briefly discussed in terms of relaxation. [Copyright &y& Elsevier]

Abstract: The structures of Cu–Zr and Ni–Zr metallic glasses have been studied by neutron diffraction and Reverse Monte Carlo (RMC) modeling. A pre-peak at Q∼17nm−1 was observed in the structure factor, S(Q), of Ni–Zr metallic glasses, and this is associated with the Ni–Ni partial structure factor was well reproduced by the RMC modeling. An analysis of Voronoi polyhedra in the RMC simulations was used to characterise the different atomic configurations around Zr, Ni and Cu atoms. The Zr environments are very similar in the two systems, but there are marked differences between the polyhedra around Ni and Cu atoms. The polyhedra around Ni atoms are dominated by trigonal prismatic-like, Archimedian antiprismatic-like, and similar polyhedra, with smaller total coordination numbers less than 10. In contrast, icosahedron-like polyhedra with total coordination numbers in excess of 11 are preferred for Cu. [Copyright &y& Elsevier]

We have synthesized iron silicides on a Si(111) substrate using an electron-beam evaporation technique in combination with thermal annealing. The microstructures, as a function of heating rate on annealing, were characterized by transmission electron microscopy (TEM). Bright-field plan-view TEM observations revealed that a discontinuous thin film is formed in the sample annealed rapidly, while complete separated nanoparticles were obtained in the specimen annealed slowly. Selected-area and nano-beam electron diffraction patterns indicated that the former and latter specimens mainly consist of iron monosilicide ( ɛ-FeSi) and iron disilicide ( β-FeSi2) phases, respectively. [ABSTRACT FROM AUTHOR]

Effects of particle size and additive element on atomic ordering of FePt nanoparticles have been examined by transmission electron microscopy and electron diffraction. Additive Ag deposited after the formation of Fe/Pt nanoparticles effectively reduces the ordering start temperature. The ordering reaction proceeds during the deposition at 673 K when the mean particle sizes are below 7 nm. [Copyright &y& Elsevier]

The ground state energy of nano particles of the CuAu alloy is calculated by utilizing the modified embedded atom method(MEAM), and a computer simulation is made of the order-disorder transition therein by Monte Carlo method with the many-body potential obtained by MEAM. The calculations have been made for three kinds of model crystals of nano particles with 2 nm and 3 nm in diameter, containing 321 and 1061 atoms, respectively, and of a bulk with a size of 5 × 5 × 5 unit cells, on which the periodic boundary condition is imposed. As a result, it is found that the difference in ground state energy between perfectly ordered and disordered states becomes less in nano particles than in the bulk, and that the critical temperature T decreases markedly with decreasing particle size. According to our previous experiments, there seems to be a certain critical size for the atomic ordering in the nano particles, and T is depressed remarkably in the nano particles. These experimental results appear to be accounted for by the present calculated ones qualitatively. [ABSTRACT FROM AUTHOR]

Objective: To determine the useful biomarker for predicting the effects of poly-(ADP ribose)-polymerase (PARP) inhibitors in Japanese patients with ovarian cancer., Methods: We collected clinical information and performed molecular biological analysis on 42 patients with ovarian, fallopian tube, and primary peritoneal carcinomas who received PARP inhibitors., Results: Among the analyzed patients with ovarian cancer, 23.8% had germline BRCA mutation ( gBRCAm ), 42.9% had homologous recombination repair-related gene mutation (HRRm), and 61.1% had a genomic instability score (GIS) of ≥42. Patients with HRRm had a significantly longer progression-free survival (PFS) than those without HRRm (median PFS 35.6 vs. 7.9 months; p=0.009), with a particularly marked increase in PFS in patients with gBRCAm (median PFS 42.3 months). Similarly, among patients with recurrent ovarian cancer, those with HRRm had a longer PFS than those without HRRm (median PFS 42.3 vs. 7.7 months; p=0.040). Multivariate Cox proportional hazards regression analysis found that performance status and gBRCAm status were independent factors associated with prolonged PFS with PARP inhibitors. In recurrent ovarian cancer, multivariate regression analysis identified platinum-free interval (PFI) in addition to performance status as a significant predictor of PFS. On the contrary, no significant association was observed between PFS and a GIS of ≥42 used in clinical practice., Conclusion: We found that HRRm can be a useful biomarker for predicting the effects of PARP inhibitors in treating ovarian cancer and that the PFI can also be useful in recurrent ovarian cancer., Competing Interests: No potential conflict of interest relevant to this article was reported., (© 2024. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology, and Japan Society of Gynecologic Oncology.)

Objectives: Pancreatic cancer (PC) has a poor prognosis and limited treatment options. Liquid biopsy, which analyzes circulating tumor DNA (ctDNA) in blood, holds promise for precision medicine; however, low ctDNA detection rates pose challenges. This study aimed to investigate the utility of wash samples obtained via endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) as a liquid biopsy for PC., Methods: A total of 166 samples (42 formalin-fixed paraffin-embedded [FFPE] tissues, 80 wash samples, and 44 plasma samples) were collected from 48 patients with PC for genomic analysis. DNA was extracted and quantified, and 60 significantly mutated genes were sequenced. The genomic profiles of FFPE tissues, wash samples, and plasma samples were compared. Finally, the ability to detect druggable mutations in 80 wash samples and 44 plasma samples was investigated., Results: The amount of DNA was significantly lower in plasma samples than in wash samples. Genomic analysis revealed a higher detection rate of oncogenic mutations in FFPE tissues (98%) and wash samples (96%) than in plasma samples (18%) and a comparable detection rate in FFPE tissues and wash samples. Tumor-derived oncogenic mutations were detected more frequently in wash samples than in plasma samples. Furthermore, the oncogenic mutations detection rate remained high in wash samples at all PC stages but low in plasma samples even at advanced PC stages. Using wash samples was more sensitive than plasma samples for identifying oncogenic and druggable mutations., Conclusions: The wash sample obtained via EUS-FNB is an ideal specimen for use as a liquid biopsy for PC., (© 2024 Wiley Periodicals LLC.)