135 research outputs found

    Structures and Magnetic Properties of Tm1-yYyMn1-xCoxO3

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    The structure and magnetic properties of Tm1−y Y y Mn1−x Co x O3 with 0 ≦ x ≦ 0.5 and 0 ≦ y ≦ 0.3 were investigated by X-ray diffraction, specific heat and magnetization measurements. Thulium manganite TmMnO3 prepared by solid-state synthesis at ambient pressure is hexagonal and antiferromagnetic with a Nèel temperature T N of 86 K. The substitution of Y for Tm in TmMnO3 does not greatly affect the fundamental hexagonal structure. The magnetization and specific heat measurement results for Tm1−y Y y MnO3 can be qualitatively explained in terms of the dilution effect of Tm by Y. On the other hand, the structure of TmMn1−x Co x O3 changes gradually from hexagonal to orthorhombic with the substitution of Co for Mn; hexagonal and orthorhombic phases coexist in samples for x ≦ 0.3 whereas TmMn0.6Co0.4O3 is almost a single orthorhombic phase. The magnetization of TmMn0.6Co0.4O3 in a field of 250 Oe increases rapidly at about 60K with decreasing temperature. The difference between zero-field-cooled (ZFC) and field-cooled (FC) magnetizations increases remarkably at about 60 K. Moreover, the temperature dependences of the ZFC and the FC magnetizations exhibit peaks at about 40 and 30K, respectively. Thus, TmMn1−x Co x O3 exhibits complex magnetic properties

    Genetic Encoding of 3-Iodo-l-Tyrosine in Escherichia coli for Single-Wavelength Anomalous Dispersion Phasing in Protein Crystallography

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    SummaryWe developed an Escherichia coli cell-based system to generate proteins containing 3-iodo-l-tyrosine at desired sites, and we used this system for structure determination by single-wavelength anomalous dispersion (SAD) phasing with the strong iodine signal. Tyrosyl-tRNA synthetase from Methanocaldococcus jannaschii was engineered to specifically recognize 3-iodo-l-tyrosine. The 1.7 Å crystal structure of the engineered variant, iodoTyrRS-mj, bound with 3-iodo-l-tyrosine revealed the structural basis underlying the strict specificity for this nonnatural substrate; the iodine moiety makes van der Waals contacts with 5 residues at the binding pocket. E. coli cells expressing iodoTyrRS-mj and the suppressor tRNA were used to incorporate 3-iodo-l-tyrosine site specifically into the ribosomal protein N-acetyltransferase from Thermus thermophilus. The crystal structure of this enzyme with iodotyrosine was determined at 1.8 and 2.2 Å resolutions by SAD phasing at CuKα and CrKα wavelengths, respectively. The native structure, determined by molecular replacement, revealed no significant structural distortion caused by iodotyrosine incorporation

    Lifetime attributable risk of radiation-induced secondary cancer from proton beam therapy compared with that of intensity-modulated X-ray therapy in randomly sampled pediatric cancer patients

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    To investigate the amount that radiation-induced secondary cancer would be reduced by using proton beam therapy (PBT) in place of intensity-modulated X-ray therapy (IMXT) in pediatric patients, we analyzed lifetime attributable risk (LAR) as an in silico surrogate marker of the secondary cancer after these treatments. From 242 pediatric patients with cancers who were treated with PBT, 26 patients were selected by random sampling after stratification into four categories: (i) brain, head and neck, (ii) thoracic, (iii) abdominal, and (iv) whole craniospinal (WCNS) irradiation. IMXT was replanned using the same computed tomography and region of interest. Using the dose-volume histograms (DVHs) of PBT and IMXT, the LARs of Schneider et al. were calculated for the same patient. All the published dose-response models were tested for the organs at risk. Calculation of the LARs of PBT and IMXT based on the DVHs was feasible for all patients. The means +/- standard deviations of the cumulative LAR difference between PBT and IMXT for the four categories were (i) 1.02 +/- 0.52% (n = 7, P = 0.0021), (ii) 23.3 +/- 17.2% (n = 8, P = 0.0065), (iii) 16.6 +/- 19.9% (n = 8, P = 0.0497) and (iv) 50.0 +/- 21.1% (n = 3, P = 0.0274), respectively (one tailed t-test). The numbers needed to treat (NNT) were (i) 98.0, (ii) 4.3, (iii) 6.0 and (iv) 2.0 for WCNS, respectively. In pediatric patients who had undergone PBT, the LAR of PBT was significantly lower than the LAR of IMXT estimated by in silico modeling. Although a validation study is required, it is suggested that the LAR would be useful as an in silico surrogate marker of secondary cancer induced by different radiotherapy techniques

    Amorphization Effect for Kondo Semiconductor CeRu₂Al₁₀

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    We measured the magnetic susceptibility , electrical resistivity , and specific heat of a sputtered amorphous (a-)CeRu2Al10 alloy. value for a-CeRu2Al10 alloy follows a Curie-Weiss paramagnetic behavior in the high-temperature region, and magnetic transition was not observed down to 2 K. The effective paramagnetic moment is 1.19 /Ce-atom. The resistivity shows a typical disordered alloy behavior, that is, small temperature dependence for the whole temperature range. We observed an enhancement of and in the low-temperature region of  K. The enhancement in is suppressed by applying a magnetic field. It is suggested that this behavior is caused by the Kondo effect

    Thermal Expansion and Magnetostriction of Heavy Fermion CeRu2Si2 at Millikelvin Temperatures

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    金沢大学理工研究域数物科学系We have measured linear thermal expansion and magnetostriction of single crystal CeRu2Si2 that is well known as a heavy fermion metamagnetic compound. Thermal expansion and magnetostriction along the a-axis (B | a) and the c-axis (B | c) were measured by the capacitive dilatometer at temperatures down to 12 mK and in magnetic fields up to 9 T. We observed a strong anisotropy between a and c axis. In addition, negative deviations from Landau-Fermi liquid behavior for thermal expansion and magnetostriction coefficients were found below 50 mK and 0.4 T indicating non Fermi liquid behavior. © 2015 The Authors. Published by Elsevier B.V.出版社

    Preliminary results of proton radiotherapy for pediatric rhabdomyosarcoma: a multi-institutional study in Japan

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    To evaluate preliminary results of proton radiotherapy (PRT) for pediatric patients with rhabdomyosarcoma (RMS). From 1987 to 2014, PRT was conducted as initial radiotherapy in 55 patients (35 males, 20 females, median age 5 years, range 0–19) with RMS at four institutes in Japan. Thirty‐one, 18, and six patients had embryonal, alveolar, and other RMS, respectively. One, 11, 37, and six patients were in IRSG groups I, II, III, and IV, respectively, and the COG risk group was low, intermediate, and high for nine, 39, and seven patients, respectively. The irradiation dose was 36–60 GyE (median: 50.4 GyE). The median follow‐up period was 24.5 months (range: 1.5–320.3). The 1‐ and 2‐year overall survival rates were 91.9% (95% CI: 84.3–99.5%) and 84.8% (95% CI 75.2–94.3%), respectively, and these rates were 100% and 100%, 97.1% and 90.1%, and 57.1% and 42.9% for COG low‐, intermediate‐, and high‐risk groups, respectively. There were 153 adverse events of Grade ≥3, including 141 hematologic toxicities in 48 patients (87%) and 12 radiation‐induced toxicities in nine patients (16%). Proton‐specific toxicity was not observed. PRT has the same treatment effect as photon radiotherapy with tolerable acute radiation‐induced toxicity

    Particle therapy for prostate cancer: The past, present and future

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    Although prostate cancer control using radiotherapy is dose‐dependent, dose–volume effects on late toxicities in organs at risk, such as the rectum and bladder, have been observed. Both protons and carbon ions offer advantageous physical properties for radiotherapy, and create favorable dose distributions using fewer portals compared with photon‐based radiotherapy. Thus, particle beam therapy using protons and carbon ions theoretically seems suitable for dose escalation and reduced risk of toxicity. However, it is difficult to evaluate the superiority of particle beam radiotherapy over photon beam radiotherapy for prostate cancer, as no clinical trials have directly compared the outcomes between the two types of therapy due to the limited number of facilities using particle beam therapy. The Japanese Society for Radiation Oncology organized a joint effort among research groups to establish standardized treatment policies and indications for particle beam therapy according to disease, and multicenter prospective studies have been planned for several common cancers. Clinical trials of proton beam therapy for intermediate‐risk prostate cancer and carbon‐ion therapy for high‐risk prostate cancer have already begun. As particle beam therapy for prostate cancer is covered by the Japanese national health insurance system as of April 2018, and the number of facilities practicing particle beam therapy has increased recently, the number of prostate cancer patients treated with particle beam therapy in Japan is expected to increase drastically. Here, we review the results from studies of particle beam therapy for prostate cancer and discuss future developments in this field

    Lifetime attributable risk of radiation-induced secondary cancer from proton beam therapy compared with that of intensity-modulated X-ray therapy in randomly sampled pediatric cancer patients

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    To investigate the amount that radiation-induced secondary cancer would be reduced by using proton beam therapy (PBT) in place of intensity-modulated X-ray therapy (IMXT) in pediatric patients, we analyzed lifetime attributable risk (LAR) as an in silico surrogate marker of the secondary cancer after these treatments. From 242 pediatric patients with cancers who were treated with PBT, 26 patients were selected by random sampling after stratification into four categories: (i) brain, head and neck, (ii) thoracic, (iii) abdominal, and (iv) whole craniospinal (WCNS) irradiation. IMXT was replanned using the same computed tomography and region of interest. Using the dose–volume histograms (DVHs) of PBT and IMXT, the LARs of Schneider et al. were calculated for the same patient. All the published dose–response models were tested for the organs at risk. Calculation of the LARs of PBT and IMXT based on the DVHs was feasible for all patients. The means ± standard deviations of the cumulative LAR difference between PBT and IMXT for the four categories were (i) 1.02 ± 0.52% (n = 7, P = 0.0021), (ii) 23.3 ± 17.2% (n = 8, P = 0.0065), (iii) 16.6 ± 19.9% (n = 8, P = 0.0497) and (iv) 50.0 ± 21.1% (n = 3, P = 0.0274), respectively (one tailed t-test). The numbers needed to treat (NNT) were (i) 98.0, (ii) 4.3, (iii) 6.0 and (iv) 2.0 for WCNS, respectively. In pediatric patients who had undergone PBT, the LAR of PBT was significantly lower than the LAR of IMXT estimated by in silico modeling. Although a validation study is required, it is suggested that the LAR would be useful as an in silico surrogate marker of secondary cancer induced by different radiotherapy techniques
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