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151.
Kimikazu Sasa Seiji Hosoya Tsutomu Takahashi Kenta Takano Yuta Ochiai 《Journal of Nuclear Science and Technology》2021,58(1):72-79
ABSTRACT Strontium-90 is one of the most important fission products due to the potential health risks of its uptake and retention in the human body. Conventional analysis techniques involve β counting, which requires ingrowth of 90Y over a period of two weeks. Accelerator mass spectrometry (AMS) has the potential to shorten the analysis time while offering a lower limit of detection than β counting. Here, Sr in samples was recovered as SrF2 to provide sufficient negative ions in the caesium-sputtering ion source. In the sample preparation step, 95–98% of Sr was recovered and 99–100% of Zr removed by ion-exchange separation. Sr recovery was ~30% in the precipitation process, and this can be improved. A maximum 500 nA beam current of SrF3 – ions was obtained from SrF2 samples mixed with PbF2. A five-anode gas ionization detector was used to avoid isobaric interference from 90Zr. The 90Sr/Sr atomic ratio background of ~6 × 10–13 (~3 mBq 90Sr) was comparable with that achieved at other AMS facilities. Good linearity in 90Sr/Sr atomic ratios was obtained from 1.75 × 10–10 to 3.38 × 10–9. Suitable techniques for sample preparation and measurement were thus achieved for 90Sr analysis by AMS. 相似文献
152.
Vojislav V. Mitic Goran Lazovic Vesna Paunovic Nenad Cvetkovic Dejan Jovanovic Sandra Veljkovic Branislav Randjelovic Branislav Vlahovic 《Ceramics International》2019,45(7):9679-9685
The world's perennial need for energy and microelectronic miniaturization brings with it a broad set of technological and scientific challenges. Materials characterized by precise microstructural architectures based on fractal analysis and ranging in size down to nano scale represent an important avenue for finding novel solutions. Deep materials structure hierarchies of this type open new possibilities in capacity according to the Heywang model, especially when extended by a fractals approach and intergranular relationships supported and recognized by their fractal nature. These developments are opening new frontiers in microelectronics miniaturization. They build on early fractal applications that were used as tools in miniaturization research and also provided application perspectives for diverse energy technologies. In other words, fractals, as a crucial concept of modern theoretical-experimental physics and materials sciences, are tightly linked to higher integration processes and microelectronics miniaturization. They also hold potential for meeting the energy exploitation challenge. In this research context, for the first time we experimentally and theoretically investigated the electrostatic field between the grains within fractal nature aspects. It is essentially a theoretical experiment based on samples of experimental microstructures imaged with SEM, as previously published in a number of other papers. We now take the research a step further by consolidating the experimental samples with respect to the predicted distribution of grains and pores within the sample mass.We make an original contribution by opening the frame of scale sizes with respect to the technical processes of consolidation. This lets us predict the constitutive elements of the microstructures – approximately equidistant grains and pores. In this paper we define in a practical manner the final target elements for experimental consolidation of real samples. It is the main bridge between a designed microstructure and related characteristics – for example, fractal dimensions and final properties of next-generation fractal microelectronics. 相似文献
153.
154.
Narimasa Sasa Masahiko Machida Hideki Matsumoto 《Journal of Low Temperature Physics》2005,138(3-4):617-622
No Heading We numerically integrate the 3-D time-dependent Gross-Pitaevskii equation suggested by Tsubota et al. [Phys.Rev.A, 65, 023603(2002)] to investigate dynamical transitions of the trapped Bose-Einstein condensate (BEC) from an initial non-vortex state to a steady vortex lattice state after the trigger of the rotation. We use the splitting-fourier method as a numerical scheme to perform stable 3-D numerical simulations with high computational efficiency. We present three stages of characteristic 3-D non-steady dynamics of vortices, i.e., the vortex penetration, the stochastic vortex wandering, the vortex lattice vibration, etc.PACS numbers: 03.75.Lm, 03.75.Kk 相似文献
155.
Djuric Z. Krstajic P. Smiljanic M. Randjelovic D. 《Quantum Electronics, IEEE Journal of》2002,38(2):197-202
We have investigated the effects of carrier diffusion on the impulse response of a resonant-cavity enhanced photodetector using our analytic expression for a short-circuit current. Our theoretical results indicate that diffusion introduces a significant tail in the temporal response of photodetectors. We show that the influence of diffusion becomes significant as the absorption width decreases. A discrepancy in bandwidth as high as 35% between our results and previous theoretical predictions is observed 相似文献
156.
Davis JA Dao LV Wen X Ticknor C Hannaford P Coleman VA Tan HH Jagadish C Koike K Sasa S Inoue M Yano M 《Nanotechnology》2008,19(5):055205
Strong suppression of the effects caused by the internal electric field in ZnO/ZnMgO quantum wells following ion-implantation and rapid thermal annealing, is revealed by photoluminescence, time-resolved photoluminescence, and band structure calculations. The implantation and annealing induces Zn/Mg intermixing, resulting in graded quantum well interfaces. This reduces the quantum-confined Stark shift and increases electron-hole wavefunction overlap, which significantly reduces the exciton lifetime and increases the oscillator strength. 相似文献
157.
Nano-graphene oxide for cellular imaging and drug delivery 总被引:8,自引:0,他引:8
Xiaoming Sun Zhuang Liu Kevin Welsher Joshua Tucker Robinson Andrew Goodwin Sasa Zaric Hongjie Dai 《Nano Research》2008,1(3):203-212
Two-dimensional graphene offers interesting electronic, thermal, and mechanical properties that are currently being explored
for advanced electronics, membranes, and composites. Here we synthesize and explore the biological applications of nano-graphene
oxide (NGO), i.e., single-layer graphene oxide sheets down to a few nanometers in lateral width. We develop functionalization
chemistry in order to impart solubility and compatibility of NGO in biological environments. We obtain size separated pegylated
NGO sheets that are soluble in buffers and serum without agglomeration. The NGO sheets are found to be photoluminescent in
the visible and infrared regions. The intrinsic photoluminescence (PL) of NGO is used for live cell imaging in the near-infrared
(NIR) with little background. We found that simple physisorption via π-stacking can be used for loading doxorubicin, a widely
used cancer drug onto NGO functionalized with antibody for selective killing of cancer cells in vitro. Owing to its small
size, intrinsic optical properties, large specific surface area, low cost, and useful non-covalent interactions with aromatic
drug molecules, NGO is a promising new material for biological and medical applications.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.
This article is published with open access at Springerlink.com 相似文献
158.
Anastasios Petropoulos Grigoris Kaltsas Danijela Randjelovic Evangelos Gogolides 《Microelectronic Engineering》2010,87(5-8):827-829
In this work a micro-flow sensor integrated in the bottom surface of a rectangular microchannel is used in order to evaluate simultaneously both the flow velocity and the pressure in various micro-flow conditions. In this way direct flow rate measurement is achieved while real-time monitoring of the corresponding flow and pressure values are obtained. The effect of the microchannel dimensions in the flow determination is also studied. An almost linear relation of ΔP/L with respect to Re was extracted, which indicates a laminar flow behavior. The friction factor, corresponding to the specific microchannel dimensions was calculated together with the f × Re value. 相似文献
159.
Hiroyuki Oigawa Kazufumi Tsujimoto Kenji Nishihara Takanori Sugawara Yuji Kurata Hayanori Takei Shigeru Saito Toshinobu Sasa Hironari Obayashi 《Journal of Nuclear Materials》2011,415(3):229-236
Reduction of burden caused by radioactive waste management is one of the most critical issues for the sustainable utilization of nuclear power. The Partitioning and Transmutation (P&T) technology provides the possibility to reduce the amount of the radiotoxic inventory of the high-level radioactive waste (HLW) dramatically and to extend the repository capacity. The accelerator-driven system (ADS) is regarded as a powerful tool to effectively transmute minor actinides (MAs) in the “double-strata” fuel cycle strategy. The ADS has a potential to flexibly manage MA in the transient phase from light water reactors (LWRs) to fast breeder reactors (FBRs), and can co-exist with FBR symbiotically and complementarily to enhance the reliability and the safety of the commercial FBR cycle. The concept of ADS in JAEA is a lead-bismuth eutectic (LBE) cooled, tank-type subcritical reactor with the power of 800 MWth driven by a 30 MW superconducting LINAC. By such an ADS, 250 kg of MA can be transmuted annually, which corresponds to the amount of MA produced in 10 units of LWR with 1 GWe. The design study was performed mainly for the subcritical reactor and the spallation target with a beam window. In Japan, Atomic Energy Commission (AEC) has implemented the check and review (C&R) on P&T technology from 2008 to 2009. In the C&R, the benefit of P&T technology, the current status of the R&D, and the way forward to promote it were discussed. 相似文献
160.
A lot of phenomena related to propagating various waves are seen when the high-speed train goes through the tunnel, the gas
pipeline is broken due to an accident or the air brake of the wagon operates. For instance, a compression wave generated ahead
of a high-speed train entering a tunnel propagates to the tunnel exit and spouts as a micro pressure wave, which causes an
exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a compression
wave propagating along a very long tunnel must be understood and the experimental information on these phenomena is required.
An experimental investigation is carried out to clarify the attenuation and distortion of the propagating compression wave
in a very long tube. Experimental results show that the strength of a compression wave decreases with distance. The attenuation
and distortion of compression waves are affected by the initial waveform of the compression wave and by the unsteady boundary
layer induced by the propagating wave. The shape of a compression wave becomes different with the propagating distance; that
is, a shock wave appears just head of a wavefront and an overshoot on pressure distribution is observed behind a shock wave
due to the transition of the unsteady boundary layer. 相似文献