安全・持続可能な物質と手法を用いるタンタル系ペロブスカイト型酸窒化物顔料の合成法の開発

内容の要約広島大学(Hiroshima University)博士(工学)Doctor of Engineeringdoctora

Local density of states and superconducting gap in the iron chalcogenide superconductor Fe1+δ_{1+\delta}Se1−x_{1-x}Tex_{x} observed by scanning tunneling spectroscopy

We report on the first investigation of the quasiparticle local density of states and superconducting gap in the iron chalcogenide superconductor Fe$_{1+\delta}$Se$_{1-x}$Te$_{x}$ ($T_{\mathrm{c}} \sim 14$ K). The surface of a cleaved crystal revealed an atomic square lattice, superimposed on the inhomogeneous background, with a lattice constant of $\sim 3.8$ \AA without any reconstruction. Tunneling spectra measured at 4.2 K exhibit the superconducting gap, which completely disappears at 18 K, with a magnitude of $\sim 2.3$ meV, corresponding to $2\Delta / k_{\mathrm{B}}T_{\mathrm{c}}=3.8$.In stark contrast to the cuprate superconductors, the value of the observed superconducting gap is relatively homogeneous, following a sharp distribution with a small standard deviation of 0.23 meV. Conversely, the normal-state local density of states observed above $T_{\mathrm{c}}$ shows spatial variation over a wide energy range of more than 1 eV, probably due to the excess iron present in the crystal.Comment: 4 pages, 5 figure

Local Measurement of Microwave Response with Local Tunneling Spectra Using Near Field Microwave Microscopy

We have designed and built a near-field scanning microwave microscope, which has been used to measure the local microwave response and the local density-of-states (LDOS) in the area including the boundary between the gold deposited and the non-deposited region on highly-orientated pyrolytic graphite at a frequency of about 7.3 GHz. We have succeeded in measuring the spatial variation of both the LDOS and the surface resistance. It can be observed that the surface resistance in gold deposited region with the metallic tunneling spectra is smaller than that in the non-deposited region with the U-shaped tunneling spectra.Comment: 3 pages, 3 figures

The Early Decline of alpha-Fetoprotein and Des-gamma-Carboxy Prothrombin Predicts the Response of Hepatic Arterial Infusion Chemotherapy in Hepatocellular Carcinoma Patients

Introduction: Molecular targeting drugs are recommended as second-line treatment for intrahepatic advanced hepatocellular carcinoma (HCC). However, in Asia, hepatic arterial infusion chemotherapy (HAIC) is also considered as a second-line treatment because it improves the survival of responders. The aim of this study was to predict responders and non-responders to HAIC with low-dose cisplatin plus 5-fluorouracil (LFP) using tumor markers. Objective and Methods: The data of 47 patients who received LFP for the first time in our hospital were analyzed retrospectively. We evaluated the association between treatment response by Response Evaluation Criteria in Solid Tumors and the changing ratio of the serum concentration of alpha-fetoprotein (AFP),Lens culinarisagglutinin-reactive fraction of AFP (AFP-L3), and des-gamma-carboxy prothrombin (DCP) 2 weeks after LFP initiation. Results: The number of patients showing a complete response (CR), a partial response (PR), stable disease (SD), and progressive disease (PD) was 0 (0%), 20 (43%), 18 (38%), and 9 (19%), respectively. The AFP ratio showed significant positive correlations for PR vs. SD (p= 0.004) and PR vs. PD (p= 0.003). The DCP ratio correlated significantly for PR vs. SD (p= 0.02). The optimal cutoff values for responders were 0.79 for the AFP ratio and 0.53 for the DCP ratio. Prediction using both or either cutoff value showed 93% sensitivity, 53% specificity, a 94% negative predictive value, and a 57% positive predictive value. Conclusion: Optimal cutoff values for AFP and DCP ratios enable prediction of nonresponders to HAIC with LFP. This simple and early assessment method allows the use of HAIC and molecular targeting drugs for HCC treatment

Accuracy, repeatability, and reproducibility of T1 and T2 relaxation times measurement by 3D magnetic resonance fingerprinting with different dictionary resolutions

[Objectives] To assess the accuracy, repeatability, and reproducibility of T₁ and T₂ relaxation time measurements by three-dimensional magnetic resonance fingerprinting (3D MRF) using various dictionary resolutions. [Methods] The ISMRM/NIST phantom was scanned daily for 10 days in two 3 T MR scanners using a 3D MRF sequence reconstructed using four dictionaries with varying step sizes and one dictionary with wider ranges. Thirty-nine healthy volunteers were enrolled: 20 subjects underwent whole-brain MRF scans in both scanners and the rest in one scanner. ROI/VOI analyses were performed on phantom and brain MRF maps. Accuracy, repeatability, and reproducibility metrics were calculated. [Results] In the phantom study, all dictionaries showed high T₁ linearity to the reference values (R² > 0.99), repeatability (CV 0.98), repeatability (CV < 6%), and reproducibility (CV ≤ 4%) for T₂ measurement. The volunteer study demonstrated high T1 reproducibility of within-subject CV (wCV) < 4% by all dictionaries with the same ranges, both in the brain parenchyma and CSF. Yet, reproducibility was moderate for T₂ measurement (wCV < 8%). In CSF measurement, dictionaries with a smaller range showed a seemingly better reproducibility (T₁, wCV 3%; T₂, wCV 8%) than the much wider range dictionary (T₁, wCV 5%; T₂, wCV 13%). Truncated CSF relaxometry values were evident in smaller range dictionaries. [Conclusions] The accuracy, repeatability, and reproducibility of 3D MRF across various dictionary resolutions were high for T₁ and moderate for T₂ measurements. A lower-resolution dictionary with a well-defined range may be adequate, thus significantly reducing the computational load. [Key Points] • A lower-resolution dictionary with a well-defined range may be sufficient for 3D MRF reconstruction. • CSF relaxation times might be underestimated due to truncation by the upper dictionary range. • Dictionary with a higher upper range might be advisable, especially for CSF evaluation and elderly subjects whose perivascular spaces are more prominent

Comparison of TGSE-BLADE DWI, RESOLVE DWI, and SS-EPI DWI in healthy volunteers and patients after cerebral aneurysm clipping

Diffusion-weighted magnetic resonance imaging is prone to have susceptibility artifacts in an inhomogeneous magnetic field. We compared distortion and artifacts among three diffusion acquisition techniques (single-shot echo-planar imaging [SS-EPI DWI], readout-segmented EPI [RESOLVE DWI], and 2D turbo gradient- and spin-echo diffusion-weighted imaging with non-Cartesian BLADE trajectory [TGSE-BLADE DWI]) in healthy volunteers and in patients with a cerebral aneurysm clip. Seventeen healthy volunteers and 20 patients who had undergone surgical cerebral aneurysm clipping were prospectively enrolled. SS-EPI DWI, RESOLVE DWI, and TGSE-BLADE DWI of the brain were performed using 3 T scanners. Distortion was the least in TGSE-BLADE DWI, and lower in RESOLVE DWI than SS-EPI DWI near air–bone interfaces in healthy volunteers (P < 0.001). Length of clip-induced artifact and distortion near the metal clip were the least in TGSE-BLADE DWI, and lower in RESOLVE DWI than SS-EPI DWI (P < 0.01). Image quality scores for geometric distortion, susceptibility artifacts, and overall image quality in both healthy volunteers and patients were the best in TGSE-BLADE DWI, and better in RESOLVE DWI than SS-EPI DWI (P < 0.001). Among the three DWI sequences, image quality was the best in TGSE-BLADE DWI in terms of distortion and artifacts, in both healthy volunteers and patients with an aneurysm clip

Hemosiderin Detection inside the Mammillary Bodies Using Quantitative Susceptibility Mapping on Patients with Wernicke-Korsakoff Syndrome

Hemorrhage inside the mammillary bodies (MMBs) is known to be one of the findings of Wernicke encephalopathy. Brain MRI of two patients with Wernicke-Korsakoff syndrome (WKS) demonstrated high susceptibility values representing hemosiderin deposition in MMBs by using quantitative susceptibility mapping (QSM). QSM provided additional information of susceptibility values to susceptibility-weighted imaging in diagnosis of WKS

Quiet Diffusion-weighted MR Imaging of the Brain for Pediatric Patients with Moyamoya Disease

PURPOSE: Diffusion-weighted MRI (DWI) is an essential sequence for evaluating pediatric patients with moyamoya disease (MMD); however, acoustic noise associated with DWI may lead to motion artifact. Compared with conventional DWI (cDWI), quiet DWI (qDWI) is considered less noisy and able to keep children more relaxed and stable. This study aimed to evaluate the suitability of qDWI compared with cDWI for pediatric patients with MMD. METHODS: In this observational study, MR examinations of the brain were performed either with or without sedation in pediatric patients with MMD between September 2017 and August 2018. Three neuroradiologists independently evaluated the images for artifacts and restricted diffusion in the brain. The differences between qDWI and cDWI were compared statistically using a chi-square test. RESULTS: One-hundred and six MR scans of 56 patients with MMD (38 scans of 15 sedated patients: 6 boys and 9 girls; mean age, 5.2 years; range, 1-9 years; and 68 scans of 42 unsedated patients: 19 boys and 23 girls; mean age, 10.7 years; range, 7-16 years) were evaluated. MR examinations were performed either with or without sedation (except in one patient). In sedated patients, no artifact other than susceptibility was observed on qDWI, whereas four artifacts were observed on cDWI (P = .04). One patient awoke from sedation during cDWI scanning, while no patient awoke from sedation during qDWI acquisition. For unsedated patients, three scans showed artifacts on qDWI, whereas two scans showed artifacts on cDWI (P = .65). Regarding restricted diffusion, qDWI revealed three cases, while two cases were found on cDWI (P = .66). CONCLUSION: qDWI induced fewer artifacts compared with cDWI in sedated patients, and similar frequencies of artifacts were induced by qDWI and by cDWI in unsedated patients. qDWI showed restricted diffusion comparable to cDWI