[en] A thermogravimetric study has been performed on the nonstoichiometry of very pure monoclinic and tetragonal zirconia, ZrO_2+δ, as a function of oxygen activity at temperatures between 900 and 1400 C. In the temperature range investigated, the deviation of stoichiometry, δ, as a function of oxygen activity is described in good approximation. These observed oxygen activity dependencies suggest that at least two types of point defects are present as majority defects in both monoclinic and tetragonal zirconia. Based on the non-stoichiometry data, it is proposed that the majority defects in both monoclinic and tetragonal zirconia are completely ionized zirconium vacancies at high oxygen activities and doubly charged oxygen vacancies at low oxygen activities, which are charge compensated by holes and electrons, respectively

[en] In this paper, hot air drying (HAD) was applied when moisture content of apple slices range from 50% to 86%, and then vacuum-filling nitrogen drying (VFND) was used till moisture content reaching 7%. Results showed that, the drying rate of apple slice during VFND period increased with temperature increment and decreased with increment of slice thickness; compared to freezing dried samples, samples dried in this research were owned lower Vc and higher flavonoid; when HAD (70°C,3.0m/s)+VFND(relative pressure 0.08MPa, 50°C) and thickness of 6.0mm, nutrients reached better levels: retentions of Vc, total phenolics and flavonoid were 1.63mg/100g, 4.07mg/100g and 2.10mg/100g, respectively. (Author)

[en] The self-energy of the photohole in 2H-TaSe₂ is measured by angle-resolved photoemission spectroscopy as a function of binding energy and temperature. In the charge-density wave (CDW) state, a structure in the self-energy is detected at ∼65 meV that cannot be explained by electron-phonon scattering. A reduction in the scattering rates below this energy indicates the collapse of a major scattering channel with the formation of the CDW state accompanying the appearance of a bosonic ''mode'' in the excitation spectrum of the system

[en] The concept of defence-in-depth is applied to CANDU (CANada Deuterium Uranium) reactor designs and operations to provide series of levels of defence to prevent accidents progressing and to provide protection for reactor and public safety. The level 2 defence-in-depth provisions are designed to detect and intercept deviation from normal operation in order to prevent anticipated operating occurrences (AOOs) from escalating to accident conditions, and to return the plant to a state of normal operations, according to the Canada Nuclear Safety Commission (CNSC) regulatory document RD-337. Historically, safety analysis has focused on the effectiveness of level 3 defence-in-depth provisions in accident conditions, and the effectiveness of level 2 defence-in-depth has not been assessed. In this study, the effectiveness of Level 2 defence-in-depth is assessed for loss of flow (LOF) events for Bruce Nuclear Generating Station (NGS) A reactors. The level 2 defence-in-depth in Bruce NGS A design is identified to be the stepback function of reactor regulating system (RRS). The behavior of RRS stepback following the initiation of loss of flow event is simulated using RFSP/TUF/RRS_-em coupled code. The behavior of full system and single channel is simulated and assessed against the acceptance criteria - fitness for service of systems, structures and components (SSCs). (author)

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No abstract available

[en] Purpose: Elekta Infinity is the one of the latest generation LINAC with unique features. Two Infinity LINACs are recently commissioned at our institution. The dosimetric and mechanical characteristics of the machines are presented. Methods: Both Infinity LINACs with Agility MLC (160 leaves with 0.5 cm leaf width) are configured with five electron energies (6, 9, 12, 15, and 18 MeV) and two photon energies (6 and 15 MV). One machine has additional photon energy (10 MV). The commissioning was performed by following the manufacturer's specifications and AAPM TG recommendations. Beam data of both electron and photon beams are measured with scanning ion chambers and linear diode array. Machines are adjusted to have the dosimetrically equivalent characteristics. Results: The commissioning of mechanical and imaging system meets the tolerances by TG recommendations. The PDD₁₀ of various field sizes for 6 and 15 MV shows < 0.5% difference between two machines. For each electron beams, R₈₀ matches with < 0.4 mm difference. The symmetry and flatness agree within 0.8% and 0.9% differences for photon beams, respectively. For electron beams, the differences of the symmetry and flatness are within 1.2% and 0.8%, respectively. The mean inline penumbras for 6, 10, and 15 MV are respectively 5.1±0.24, 5.6±0.07, and 5.9±0.10 mm for 10x10 cm at 10 cm depth. The crossline penumbras are larger than inline penumbras by 2.2, 1.4, and 1.0 mm, respectively. The MLC transmission factor with interleaf leakage is 0.5 % for all photon energies. Conclusion: The dosimetric and mechanical characteristics of two Infinity LINACs show good agreements between them. Although the Elekta Infinity has been used in many institutions, the detailed characteristics of the machine have not been reported. This study provides invaluable information to understand the Infinity LINAC and to compare the quality of commissioning data for other LINACs

[en] This work investigates resonances in a capacitively coupled, low pressure krypton microdischarge operated at 2.5 GHz. A circuit model for the device, which has a length dimension of approximately 1 mm, calculates impedance values for a range of electron densities. The model results predict several 'parallel' and 'series' resonances at the driving frequency when the electron density is approximately 8 x 10¹¹ cm^-3 and 5 x 10¹² cm^-3. The series resonance occurs when the resistance approaches the output impedance of the radio-frequency signal source, minimizing the reflected power. These resonances explain an experimentally observed jump in intensity with increasing input power.

[en] The US Department of Energy (DOE) is responsible for cleanup activities at a number of facilities under its Environmental Restoration and Waste Management Program. The major goals of this program are to eliminate potential hazards to human health and the environment that are associated with contamination of these sites and, to the extent possible, make surplus real property available for other uses. The assessment of potential baseline health risks and ecological impacts associated with a contaminated site is an important component of the remedial investigation/feasibility study (RI/FS) process required at all Superfund sites. The purpose of this paper is to describe one phase of the baseline assessment, i.e., the characterization of human health risks associated with exposure to chemical contaminants in air and on interior building surfaces at a contaminated site. The model combines data on human activity patterns in a particular microenvironment within a building with contaminant concentrations in that microenvironment to calculate personal exposure profiles and risks within the building. The results of the building assessment are presented as probability distribution functions and cumulative distribution functions, which show the variability and uncertainty in the risk estimates

[en] Spatially resolved measurements of the density of metastable excited atoms in the plume of an argon microplasma are presented. The microplasma device is operated at a relatively low pressure, on the order of 1 Torr, and is exhausted into a vacuum. Line-integrated densities of excited argon neutrals in the exhaust plume are measured using tunable diode laser absorption spectroscopy. The densities of argon metastables in both 1s₅ and 1s₃ states are measured. These line-integrated density measurements are converted to three-dimensional density maps using the Abel inversion. The density of 1s₅ argon peaks at a value of approximately 10¹⁸ m^-3 near the outlet orifice, while the 1s₃ density is roughly five times lower everywhere. It is found that, far from the face of the microplasma outlet orifice, metastable density follows axial and angular distributions consistent with that expected of vacuum gas expansion as predicted by classic rarified flow theory. Integrated metastable density is found to be conserved as the plume expands through 4 mm, suggesting a net production of excited species in the first millimetre and a constant population further downstream.