Controlling oxygen coordination and valence of network forming cations

Understanding the structure-property relationship of glass material is still challenging due to a lack of periodicity in disordered materials. Here, we report the properties and atomic structure of vanadium phosphate glasses characterized by reverse Monte Carlo modelling based on neutron/synchrotron X-ray diffraction and EXAFS data, supplemented by Raman and NMR spectroscopy. In vanadium-rich glass, the water durability, thermal stability and hardness improve as the amount of P2O5 increases, and the network former of the glass changes from VOx polyhedra to the interplay between VOx polyhedra and PO4 tetrahedra. We find for the first time that the coordination number of oxygen atoms around a V4+ is four, which is an unusually small coordination number, and plays an important role for water durability, thermal stability and hardness. Furthermore, we show that the similarity between glass and crystal beyond the nearest neighbour distance is important for glass properties. These results demonstrate that controlling the oxygen coordination and valence of the network-forming cation is necessary for designing the properties of glass

Structure and Ionic Diffusion in Molten NaI, RbI, and NaI-RbI mixture

Static structure factors of molten NaI, RbI, and their mixture of (RbI)0.3(NaI)0.7 are measured up to high-Q region by using the high-energy Xray diffraction technique. Moreover, molecular dynamics (MD) simulations are carried out, and the simulation results well reproduce the diffraction data. The partial structure factors, partial pair distribution functions, and ionic diffusion coefficients calculated by the MD simulations are reported in detail. The mixing effects of cations on the structure and ionic diffusion are also discussed

Structure and properties of densified silica glass: characterizing the order within disorder

世界一構造秩序のあるガラスの合成と構造解析に成功 --ガラスの一見無秩序な構造の中に潜む秩序を抽出--. 京都大学プレスリリース. 2021-12-25.The broken symmetry in the atomic-scale ordering of glassy versus crystalline solids leads to a daunting challenge to provide suitable metrics for describing the order within disorder, especially on length scales beyond the nearest neighbor that are characterized by rich structural complexity. Here, we address this challenge for silica, a canonical network-forming glass, by using hot versus cold compression to (i) systematically increase the structural ordering after densification and (ii) prepare two glasses with the same high-density but contrasting structures. The structure was measured by high-energy X-ray and neutron diffraction, and atomistic models were generated that reproduce the experimental results. The vibrational and thermodynamic properties of the glasses were probed by using inelastic neutron scattering and calorimetry, respectively. Traditional measures of amorphous structures show relatively subtle changes upon compacting the glass. The method of persistent homology identifies, however, distinct features in the network topology that change as the initially open structure of the glass is collapsed. The results for the same high-density glasses show that the nature of structural disorder does impact the heat capacity and boson peak in the low-frequency dynamical spectra. Densification is discussed in terms of the loss of locally favored tetrahedral structures comprising oxygen-decorated SiSi4 tetrahedra

Cell Line Models for Acquired Resistance to First-Line Osimertinib in Lung Cancers—Applications and Limitations

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are first-line drugs for lung cancers with activating EGFR mutations. Although first- and second-generation EGFR-TKIs were standard first-line treatments, acquired resistance (AR) to these drugs is almost inevitable. Cell line models have been widely used to explore the molecular mechanisms of AR to first- and second-generation EGFR-TKIs. Many research groups, including ours, have established AR cell lines that harbor the EGFR T790M secondary mutation, MET gene amplification, or epithelial–mesenchymal transition (EMT) features, which are all found in clinical specimens obtained from TKI-refractory lesions. Currently, many oncologists prescribe osimertinib, a third-generation EGFR-TKI that can overcome T790M-mediated resistance, as a first-line TKI. Although few clinical data are available about AR mechanisms that arise when osimertinib is used as a first-line therapy, many research groups have established cell lines with AR to osimertinib and have reported on their AR mechanisms. In this review, we summarize the findings on AR mechanisms against first-line osimertinib obtained from analyses of cell line models

次世代シーケンサーによる外科切除症例におけるctDNAの再発予測因子としての意義

本研究ではCAPP-SeqとSignateraを用いて術後の予後予測やctDNAの状態と画像検査における再発の関係を評価した。術後すぐの解析（術後中央値9日、範囲2-53日)では5人の患者がctDNA陽性となり全例が再発し、ctDNA陽性は有意に予後不良であった。さらに経過観察中に5人の患者がctDNA陽性となり全例が再発した。また経過観察中に1回でもctDNAが検出されると、有意に予後不良であった。ctDNA陽性の画像検査に対するリードタイム中央値は2.8（0-12.8）カ月であった。ctDNA陰性は予後良好な転帰と関連しており、長期の陰性適中率は83.3％（30/36人）であった。In this study, we used CAPP-Seq and Signatera to evaluate the relationship between postoperative prognostic and ctDNA status and recurrence on imaging studies. In a landmark analysis (median 9 days postoperatively, range 2-53 days), 5 patients tested positive for ctDNA and all recurred, with ctDNA positivity associated with a significantly worse prognosis. Five more patients tested positive for ctDNA during follow-up, and all relapsed. The prognosis was significantly worse if ctDNA was detected at least once during follow-up. Overall, the median lead time for ctDNA-positive imaging was 2.8 (0-12.8) months. ctDNA negativity was associated with a favorable outcome, with a long-term negative predictive value of 83.3% (30/36 patients).研究分野：Thoracic surger

Structure and Ionic Diffusion in Molten NaI, RbI, and NaI-RbI mixture

Static structure factors of molten NaI, RbI, and their mixture of (RbI)0.3(NaI)0.7 are measured up to high-Q region by using the high-energy Xray diffraction technique. Moreover, molecular dynamics (MD) simulations are carried out, and the simulation results well reproduce the diffraction data. The partial structure factors, partial pair distribution functions, and ionic diffusion coefficients calculated by the MD simulations are reported in detail. The mixing effects of cations on the structure and ionic diffusion are also discussed

The Significance of ctDNA as a Predictor of Recurrence in Surgical Resection Cases Using Next-Generation Sequencing

本研究ではCAPP-SeqとSignateraを用いて術後の予後予測やctDNAの状態と画像検査における再発の関係を評価した。術後すぐの解析（術後中央値9日、範囲2-53日)では5人の患者がctDNA陽性となり全例が再発し、ctDNA陽性は有意に予後不良であった。さらに経過観察中に5人の患者がctDNA陽性となり全例が再発した。また経過観察中に1回でもctDNAが検出されると、有意に予後不良であった。ctDNA陽性の画像検査に対するリードタイム中央値は2.8（0-12.8）カ月であった。ctDNA陰性は予後良好な転帰と関連しており、長期の陰性適中率は83.3％（30/36人）であった。In this study, we used CAPP-Seq and Signatera to evaluate the relationship between postoperative prognostic and ctDNA status and recurrence on imaging studies. In a landmark analysis (median 9 days postoperatively, range 2-53 days), 5 patients tested positive for ctDNA and all recurred, with ctDNA positivity associated with a significantly worse prognosis. Five more patients tested positive for ctDNA during follow-up, and all relapsed. The prognosis was significantly worse if ctDNA was detected at least once during follow-up. Overall, the median lead time for ctDNA-positive imaging was 2.8 (0-12.8) months. ctDNA negativity was associated with a favorable outcome, with a long-term negative predictive value of 83.3% (30/36 patients).研究分野：Thoracic surger

Structure and Ionic Diffusion in Molten NaI, RbI, and NaI-RbI mixture

Static structure factors of molten NaI, RbI, and their mixture of (RbI)0.3(NaI)0.7 are measured up to high-Q region by using the high-energy Xray diffraction technique. Moreover, molecular dynamics (MD) simulations are carried out, and the simulation results well reproduce the diffraction data. The partial structure factors, partial pair distribution functions, and ionic diffusion coefficients calculated by the MD simulations are reported in detail. The mixing effects of cations on the structure and ionic diffusion are also discussed

Structure of alumina glass

The fabrication of novel oxide glass is a challenging topic in glass science. Alumina (Al2O3) glass cannot be fabricated by a conventional melt–quenching method, since Al2O3 is not a glass former. We found that amorphous Al2O3 synthesized by the electrochemical anodization of aluminum metal shows a glass transition. The neutron diffraction pattern of the glass exhibits an extremely sharp diffraction peak owing to the significantly dense packing of oxygen atoms. Structural modeling based on X-ray/neutron diffraction and NMR data suggests that the average Al–O coordination number is 4.66 and confirms the formation of OAl3 triclusters associated with the large contribution of edge-sharing Al–O polyhedra. The formation of edge-sharing AlO5 and AlO6 polyhedra is completely outside of the corner-sharing tetrahedra motif in Zachariasen’s conventional glass formation concept. We show that the electrochemical anodization method leads to a new path for fabricating novel single-component oxide glasses.ISSN:2045-232