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81.
Hematopoietic stem cells (HSCs) are the only cell population that possesses both a self-renewing capacity and multipotency, and can give rise to all lineages of blood cells throughout an organism’s life. However, the self-renewal capacity of HSCs is not infinite, and cumulative evidence suggests that HSCs alter their function and become less active during organismal aging, leading ultimately to the disruption of hematopoietic homeostasis, such as anemia, perturbed immunity and increased propensity to hematological malignancies. Thus, understanding how HSCs alter their function during aging is a matter of critical importance to prevent or overcome these age-related changes in the blood system. Recent advances in clonal analysis have revealed the functional heterogeneity of murine HSC pools that is established upon development and skewed toward the clonal expansion of functionally poised HSCs during aging. In humans, next-generation sequencing has revealed age-related clonal hematopoiesis that originates from HSC subsets with acquired somatic mutations, and has highlighted it as a significant risk factor for hematological malignancies and cardiovascular diseases. In this review, we summarize the current fate-mapping strategies that are used to track and visualize HSC clonal behavior during development or after stress. We then review the age-related changes in HSCs that can be inherited by daughter cells and act as a cellular memory to form functionally distinct clones. Altogether, we link aging of the hematopoietic system to HSC clonal evolution and discuss how HSC clones with myeloid skewing and low regenerative potential can be expanded during aging. 相似文献
82.
Naoto Kakuta Katsuya Kondo Atsushi Ozaki Hidenobu Arimoto Yukio Yamada 《International Journal of Heat and Mass Transfer》2009,52(19-20):4221-4228
This paper presents a method of imaging temperature distributions of sub-millimeter-thick water using a near-infrared camera and optical narrow-bandpass filter. The principle is based on the temperature dependence of the ν1 + ν3 absorption band of water. Temperature images are constructed by measuring the absorbance of water at the wavelength of 1412 nm through the filter for all pixels of the camera. From calibration measurements on 0.5-mm thick water at temperatures from 26.0 °C to 40.0 °C, the temperature coefficient was 6.3 × 10?4 K?1 and the standard deviation of absorbance was 1.9 × 10?4. Thermal diffusion in 0.5-mm thick water caused by a thin heating wire was visualized with this method. The obtained images were verified against temperature distributions calculated by solving a two-dimensional thermal conduction model. This method would be useful for temperature measurement applications and control of aqueous solutions in microchips. 相似文献
83.
Zhengxin Liu Atsushi Masuda Takehiko Nagai Takashi Miyazaki Miwako Takano Masahiro Takano Haruyuki Yoshigahara Kazutoshi Sakai Koichi Asai Michio Kondo 《Solar Energy Materials & Solar Cells》2007,91(19):1805-1810
Spherical Si solar cell, which is made up of Si spheres with a diameter of approximately 1.0 mm, is expected to be a promising candidate for low consumption of Si feedstock and simple process technology. This paper describes the formation process and the structure of a concentrator module in detail. The concentrator lens was formed by casting with ultraviolet light hardening resin. The concentration ratio was 4.4 times and the pitch between the spheres was 2.0 mm. By this module design, it was possible to realize a consumption of the Si feedstock of about 3.0 g/W. Conversion efficiencies of 11.3% from single-sphere cell, 8.5% from a 23-spheres module and 5.2% from a 105-spheres module under AM1.5, 100 mW/cm2 illumination were achieved. 相似文献
84.
Conservation laws of mass, momentum, and energy for the thermo-inelastic body in the region involving the moving interface between the solid and liquid are introduced to derive jump conditions of velocity, stress, and energy on the interface as the sequence of local form for the generalized Reynolds transport theorem. The jump condition of energy is revealed to be the generalized Stefan condition for moving interface problems. The finite element formulation is used to analyze the modes of flow, deformation, and stresses in a melting or solidifying process by employing a viscoplastic constitutive equation that describes the mechanical behavior of both the solid and liquid phases. The mathematical formalism is applied to simulate bead-on plate welding. 相似文献
85.
Heat transfer characteristics of a swirling impinging jet have been experimentally examined using a combined particle image velocimetry (PIV) and laser‐induced fluorescence (LIF) technique for simultaneous measurement of velocity and temperature fields. The present study shows that the radial width of the jet stretches with increasing swirl intensity, and that the stretching phenomenon contributes to the maximum local heat transfer coefficient. At the stagnation region, the flow near the heated surface is mixed intermittently by reverse flows toward upstream, and spatial distributions of temperature are correlated with instantaneous velocity vector maps. The dynamic behavior of recirculation zones, attributed to swirl number Sw and impinging distance, mainly determines the turbulent heat transfer at the stagnation region. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(8): 663–673, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10120 相似文献
86.
A straight-bladed vertical axis wind turbine with a directed guide vane row — Effect of guide vane geometry on the performance — 总被引:2,自引:0,他引:2
Manabu Takao Hideki Kuma Takao Maeda Yasunari Kamada Michiaki Oki Atsushi Minoda 《热科学学报(英文版)》2009,18(1):54-57
The objective of this study is to show the effect of guide vane geometry on the performance. In order to overcome the disadvantages
of vertical axis wind turbine, a straight-bladed vertical axis wind turbine (S-VAWT) with a directed guide vane row has been
proposed and tested by the authors. According to previous studies, it was clarified that the performance of the turbine can
be improved by means of the directed guide vane row. However, the guide vane geometry of S-VAWT has not been optimized so
far. In order to clarify the effect of guide vane geometry, the effects of setting angle and gap between rotor blade and guide
vane on power coefficient and starting characteristic were investigated in the experiments. The experimental study of the
proposed wind turbine was carried out by a wind tunnel. The wind tunnel with a diameter of 1.8m is open jet type. The wind
velocity is 8 m/s in the experiments. The rotor has three straight blades with a profile of NACA0018 and a chord length of
100 mm, a diameter of 0.6 m and a blade height of 0.7 m. The guide vane row consists of 3 arc plates. 相似文献
87.
88.
Yoshihiro Hayashi Takuya Oishi Kaede Shirotori Yuki Marumo Atsushi Kosugi Shungo Kumada 《Drug development and industrial pharmacy》2018,44(7):1090-1098
Objectives: The aim of this study was to explore the potential of boosted tree (BT) to develop a correlation model between active pharmaceutical ingredient (API) characteristics and a tensile strength (TS) of tablets as critical quality attributes.Methods: First, we evaluated 81 kinds of API characteristics, such as particle size distribution, bulk density, tapped density, Hausner ratio, moisture content, elastic recovery, molecular weight, and partition coefficient. Next, we prepared tablets containing 50% API, 49% microcrystalline cellulose, and 1% magnesium stearate using direct compression at 6, 8, and 10?kN, and measured TS. Then, we applied BT to our dataset to develop a correlation model. Finally, the constructed BT model was validated using k-fold cross-validation.Results: Results showed that the BT model achieved high-performance statistics, whereas multiple regression analysis resulted in poor estimations. Sensitivity analysis of the BT model revealed that diameter of powder particles at the 10th percentile of the cumulative percentage size distribution was the most crucial factor for TS. In addition, the influences of moisture content, partition coefficients, and modal diameter were appreciably meaningful factors.Conclusions: This study demonstrates that BT model could provide comprehensive understanding of the latent structure underlying APIs and TS of tablets. 相似文献
89.
Nano-structured arrays are engineered to meet the requirements of a variety of applications such as microfilters, sensors, and structural interface due to their unique mechanical characteristics, which cannot be achieved by conventional solid materials. However, it is hard to evaluate the elastic properties of nano-structured arrays owing to the discrete structure, sample size, and availability of suitable techniques. To facilitate this, we develop an advanced three-dimensional microscale vibration testing process. In the test, a specially designed three-dimensional microspecimen with tuned mass is excited by a piezoelectric actuator, and the resonance frequencies are detected by a laser device successfully. The anisotropic elastic moduli of nano-structured array composed of helical nano-springs are identified from a single spectrum. This array shows so strong characteristic anisotropy that the solid one hardly can attain. The microscale testing technique can be extended to other materials and microstructures. 相似文献
90.
Yoshitaka Chikazawa Atsushi Katoh Hiroyuki Obata Masayuki Uzawa Kazuhiro Koga Ryo Chishiro 《Journal of Nuclear Science and Technology》2013,50(4):437-447
A simplified fuel handling system design for the demonstration Japan sodium-cooled fast reactor (JSFR) has been proposed. Fast Reactor Cycle Technology Development project phase I results of key technology evaluations on a pantograph fuel handling machine (FHM), a fuel transfer pot with two core component positions, dry spent fuel cleaning and minor actinide-bearing fresh fuel shipping cask are summarized. A full-scale FHM mockup has been fabricated and tested in the air accumulating performance and seismic tolerance data. A mockup fuel transfer pot with fins and chromium carbide coating has been fabricated and tested with sodium accumulating heat transfer performance data. Several sodium cleaning tests using a dummy subassembly has been conducted accumulating cleaning performance data. For fresh fuel shipping cask, a design tool for evaluation of heat transfer capability has been developed and a helium gas cask shows cooling capability of minor actinide-bearing fresh fuel. Those experimental and analytical efforts have shown that key technologies to develop simplified fuel handling system are matured enough to proceed large-scale sodium experiments and conceptual design study for the demonstration JSFR. 相似文献