Author Keywords: Radiation detection; Long-lasting phosphor; Luminescence; Temperature dependence; Fade-out effect 相似文献
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1.
Keita Ikeue Shingo Ando Tomohiro Mitsuyama Yusuke Ohta Keishi Arayama Akiko Tsutsumi Masato Machida 《Topics in Catalysis》2008,47(3-4):175-180
Lanthanide-based oxysulfides and sulfide, LnTaO3.5S0.5, Ln10OS14 (Ln = La, Pr, Nd, Sm) and La4In5S13, were successively synthesized by sulfurization in a flowing H2S. The sulfurization decreased the band-gap energies from >4 eV to <3eV, because of the formation of occupied S3p orbitals
on the top of valence band. In accordance with the small band gap, the H2 evolution from a 0.01 M Na2S and 0.01 M Na2SO3 solution system was observed under irradiation of light up to >500 nm. The rate of H2 evolution under light irradiation of >500 nm increased in the order of Ni/LaTaO3.5S0.5 < Ru/La10OS14 < Pt/La4In5S13. 相似文献
2.
Munehiko Kowatari Daisuke Koyama Yoshiyuki Satoh Kouichi Iinuma Shunsuke Uchida 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2002,480(2-3):431-439
The temperature dependence of luminescence from a long-lasting phosphor (LLP), SrAl2O4 : Eu2+,Dy3+, exposed to ionizing radiation has been measured to understand the LLP luminescence mechanism. Evaluation of the decay constants of the LLP exposed to -, β- or γ-rays at temperatures from 200 to 390 K showed that the decay constant is divided into four components ranging from 10−4 to 10−1 s−1 with activation energies of 0.02–0.35 eV.
Total luminous intensity from the LLP with changing irradiation temperature has its maximum value around the room temperature. Irradiation at elevated temperature (390 K) has the total luminescence pattern with monotonous decrease as temperature rises. As a result of evaluating the temperature dependence of luminescence, the luminescence mechanism is considered as follows:
3.
Keiji Itabashi Takuji Ikeda Akihiko Matsumoto Kunikazu Kamioka Masanao Kato Kazuo Tsutsumi 《Microporous and mesoporous materials》2008,114(1-3):495-506
Four types of Rb-aluminosilicate zeolites were hydrothermally synthesized in pure phase for the first time from Rb-aluminosilicate gels without using any organic structure-directing agent (SDA) under stirring conditions. The crystal structure of each zeolite was refined by Rietveld analysis of the X-ray diffraction (XRD) data. These crystal structures were confirmed to be Rb-mordenite, Rb-merlinoite, a new aluminosilicate zeolite with an ATT framework topology, and Rb-offretite denoted by RMA-1, RMA-2, RMA-3, and RMA-4, respectively. The Si/Al ratio of RMA-1 with an MOR topology varied from 5.3 to 8.0; however, the variation of the Si/Al ratios of the other zeolites was rather small. The crystal system of RMA-2 was tetragonal with space group I4/mmm, where two Rb sites were distributed at the center of an 8-membered ring (MR). On the other hand, two Rb sites in RMA-3 were located at the center of the 8-MR in small two cages. The structure of RMA-4 was identified as the OFF type with a local disorder or defect, which included a small amount of an intergrown ERI phase. 相似文献
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6.
Asako Yamamoto Lingli Yang Yasutaka Kuroda Jiao Guo Lanting Teng Daisuke Tsuruta Ichiro Katayama 《International journal of molecular sciences》2021,22(1)
As the outermost barrier of the body, skin is a major target of oxidative stress. In the brain, estrogen has been reported synthesized locally and protects neurons from oxidative stress. Here, we explored whether estrogen is also locally synthesized in the skin to protect from oxidative stress and whether aberrant local estrogen synthesis is involved in skin disorders. Enzymes and estrogen receptor expression in skin cells were examined first by quantitative real-time PCR and Western blot analyses. Interestingly, the estrogen synthesis enzyme was mainly localized in epidermal keratinocytes and estrogen receptors were mainly expressed in melanocytes among 13 kinds of cultured human skin cells. The most abundant estrogen synthesis enzyme expressed in the epidermis was 17β-hydroxysteroid dehydrogenase 1 (HSD17β1) localized in keratinocytes, and the most dominant estrogen receptor expressed in the epidermis was G protein-coupled estrogen receptor 1 (GPER1) in melanocytes. To investigate whether keratinocyte-derived estradiol could protect melanocytes from oxidative stress, cultured human primary epidermal melanocytes (HEMn-MPs) were treated with H2O2 in the presence or absence of 17β estradiol or co-cultured with HSD17β1 siRNA-transfected keratinocytes. Keratinocyte-derived estradiol exhibited protective effects against H2O2-induced cell death. Further, reduced expression of HSD17β1 in the epidermis of skin from vitiligo patients was observed compared to the skin from healthy donors or in the normal portions of the skin in vitiligo patients. Our results suggest a possible new target for interventions that may be used in combination with current therapies for patients with vitiligo. 相似文献
7.
Dr. Daisuke Okuno Dr. Noriho Sakamoto Dr. Mohammed S. O. Tagod Yoshiko Akiyama Dr. Sakiko Moriyama Dr. Takuto Miyamura Dr. Atsuko Hara Dr. Takashi Kido Dr. Hiroshi Ishimoto Prof. Yuji Ishimatsu Prof. Takashi Tanaka Prof. Jun Ishihara Prof. Kohsuke Takeda Prof. Yoshimasa Tanaka Prof. Hiroshi Mukae 《ChemMedChem》2021,16(16):2515-2523
Heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, is causally related to fibrotic diseases, including idiopathic pulmonary fibrosis. The identification of Compounds that interfere with the HSP47-collagen interaction is essential for the development of relevant therapeutics. Herein, we prepared human HSP47 as a soluble fusion protein expressed in E. coli and established an assay system for HSP47 inhibitor screening. We screened a natural and synthetic Compound library established at Nagasaki University. Among 1023 Compounds, 13 exhibited inhibitory activity against human HSP47, of which three inhibited its function in a dose-dependent manner. Epigallocatechin-3-O-gallate, one of these three Compounds, is a typical polyphenol Compound derived from tea leaves. Structurally related Compounds were synthesized and examined for their activity, revealing a hydroxyl group at A-ring position 5 as important for its activity. The present findings provide valuable insight for the development of natural product-derived therapeutics for fibrotic diseases, including idiopathic pulmonary fibrosis. 相似文献
8.
Toshihide Suzuki Teruo Miyazawa Kenshiro Fujimoto Miki Otsuka Masako Tsutsumi 《Lipids》1993,28(8):775-778
The levels of phosphatidylcholine hydroperoxide in serially cultured human fetal diploid fibroblasts at various population
doubling levels were determined by high-performance liquid chromatography combined with chemiluminescence detections. This
methodology utilizes a mixture of cytochromec and luminol as post-column hydroperoxide group specific luminescent reagents. The cellular hydroperoxide content increased
with age from 0.34 to 27.72 pmol/106 cells. At the end of the cells'in vitro lifespan (51st population doubling level), the hydroperoxide content per 106 cells reached about 80 times the level found in cells of the 20th population doubling level. Supplementation of exogenous
α-tocopherol to the culture medium prevented hydroperoxide accumulation, but did not extent the lifespanin vitro. The results indicate that substantial intracellular phospholipid hydroperoxide accumulation occurred in the course of aging
of human fetal liploid fibroblasts. 相似文献
9.
Atsuhiko Yamanaka Tooru Kitagawa Masayuki Tsutsumi Toshihiro Kashima Hiroyuki Fujishiro Kimiko Ema Yoshinobu Izumi Shigehiro Nishijima 《应用聚合物科学杂志》2004,93(6):2918-2925
High strength polyethylene fiber (Toyobo, Dyneema® fiber: hereinafter abbreviated to DF) has a negative thermal expansion coefficient. Relation between fiber structure and thermal strain of DF used as reinforcement of DF reinforced plastic (DFRP) for cryogenic use was investigated. The crystallinities and orientation angles of several kinds of polyethylene fibers having different modulus from 15 to 134Gpa (herein after abbreviated to DFs) were measured by NMR and X‐ray. We obtained the parameters of the mechanical series‐parallel model composed of crystal and amorphous by crystallinity and modulus. Thermal expansion coefficients of DFs were estimated by mechanical series‐parallel model. All DFs having different modulus showed negative thermal expansion coefficients in the temperature range from 180 to 300K, and absolute values of those markedly increased by increasing tensile modulus of DF. The estimated thermal expansion coefficients showed negative values, and thermal strains showed a similar curve to observed ones mostly. Average thermal expansion coefficients in the temperature range from 180 to 300K estimated by mechanical model agreed with the observed ones. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2918–2925, 2004 相似文献
10.
Y. Tsutsumi 《Powder Technology》1973,7(3):181-188
The volume of the unit cell of a powder bed in a general case is calculated, and an equation is proposed for calculating the porosity of the bed consisting of uniformly sized ellipsoidal particles in contact and regularly arranged. In the case of uniformly sized spherical particles in contact, the equation can be simplified.Three dimensions and face angles of the unit cell are given for each regular arrangement both in cases of ellipsoidal and spherical particles. The values of the porosity are calculated by using the author's equation: the results for both ellipsoids and spheres are equal when tire particle arrangements are the same.The face angles of the unit cells proposed by Graton and Fraser are modified in two cases by the author's method of calculation and a system omitted from their classification is described. Other equations for calculation of the porosity are discussed. 相似文献