Effect of ion irradiation on structure and thermal evolution of the Ni–C60 hybrid systems

We report on the thermal response of the transition metal/fullerene thin hybrid multilayers, pristine and ion-modified, i.e., Ni/C₆₀/Ni and Ni/a-C/Ni (a-C amorphous carbon), both prepared on the MgO(1 0 0) monocrystalline substrate. The multilayer sequences were gradually annealed up to high temperatures and their structures were inspected using several analytical techniques. The inspection evidenced differences in the evolution of the virgin and ion-irradiated systems. In pristine (non-irradiated) composites (analyzed in the previous experiment) a significant part of the fullerene molecules out-diffused during annealing < 500 °C. At temperatures around (and above) 500 °C fullerenes underwent (in the vicinity of Ni) massive fragmentation and conversion to a-C. Very high temperature (1000 °C) annealing resulted in the fabrication of an array of micrometer-sized octagonal pits and rod-type particles emerging from the encompassing a-C + Ni mixture. Ion irradiated multilayers (analyzed in the current experiment) developed in a different way. Thermal annealing < 500 °C had only a minor effect on the integrity and composition of the system. Higher temperatures > 500 °C, however, induced a forceful phase separation. The nominal annealing at 1000 °C resulted in the formation of facetted, sub-micrometer-sized (round, plate and rod-type) particles (with a Ni core and a thin a-C rind) that were spread individually (without a complex a-C + Ni matrix) on a thin a-C/MgO(1 0 0) interface. The main axes of the particles were oriented according to the crystallographic axis of the MgO(1 0 0) substrate.     

The thermal regions of the NPU “Topax”: Calculated basis and experimental confirmation

Conclusions Flight tests of two production models of the NPU Topaz confirmed the correspondence of the thermal state of the NPU assembly to the formulated limits throughout prestart preparation, launch, and orbital flight. Thus was shown the well-established basic accuracy of derived solutions of heat shielding and the methodology of experimental operation of thermophysical modes as well as the effectiveness of developed calculational methods. It is especially worth emphasizing that established methods of calculation, refined through testing of NPU models, are highly accurate for the definition of the thrmal state of an NPU underground-based and flight conditions. It is advisable to make use of these results of flight tests for the second generation of the Topaz thermal emissivity NPU.Krasnaya Zvezda Scientific Production Association. Translated from Atomnaya Energiya, Vol. 71, No. 5, pp. 391–396, November, 1991.     

The δ′/δ phase transition in hafnium hydride and deuteride

Bulk samples of hafnium (Hf) hydride and deuteride were prepared and the thermal properties, heat capacity (C_P) and thermal conductivity (κ) were measured. In the C_P–temperature curves for both samples, typical lambda-type peaks were observed at around 350 K, which was due to the second-order phase transition from the δ′-phase to the δ-phase. In Hf hydride, it is considered that the δ′-phase and the δ-phase consist of regularly arranged and randomly arranged hydrogen atoms, respectively. Therefore, it can be said that the δ′/δ phase transition observed in both Hf hydride and deuteride is an order–disorder phase transition. The values of κ as well as C_P changed significantly at around the phase transition temperature.     

Overview of design and thermal–hydraulic analysis of Indian solid breeder blanket concept

India has developed two concepts of breeding blanket for the DEMO reactor: one is Lead Lithium Ceramic Breeder (LLCB), and the other one is Helium-cooled Ceramic Breeder (HCCB) concept. Indian HCCB concept is having edge on configuration of helium-cooled solid breeder with RAFMS structure. Li₂TiO₃/Li₄SiO₄ and beryllium are used as the tritium breeder and neutron multiplier, respectively. 2D thermal–hydraulic simulation studies using ANSYS have been performed based on the heat load obtained from neutronics calculations to confirm heat removal under ITER pulsed operation. Transient thermal analysis has been simulated in ANSYS for the ITER relevant operational conditions. Thermal analysis provides important information about the temperature distribution in different materials used and their temperature–time histories. Result of thermal–hydraulic simulations shows that in each cycle, the maximum temperature of all materials remains same. The peak temperatures of all materials are well within their limiting value. Concept designs of HCCB blanket and its thermal hydraulic analysis will be presented in this paper.     

The Property and Application of Arachidonic Acid

Arachidonic acid(AA) is one of the most important PUFAs(polyunsaturated fatty acids) in human body.A high-yield arachidonic acid-producing strain(mortierella aplina) was selected by ion implantation(the relative content of arachidonic acid is 70.2% among all fatty acids).This paper mainly introduced the structure,distribution,source,physiologic healthcare function and application of AA.     

Comparison of δ13C and 14C activities of CO2 samples combusted in closed-tube and elemental-analyzer systems

For combustion of organic samples, a closed tube-combustion (CTC) method is generally used, but this method requires much time and labor. The AMS facility at the Center for Chronological Research, Nagoya University, has established a CO₂ production and purification system using an elemental analyzer (EA) connected to cryogenic traps. This system enables faster combustion and CO₂ purification of samples than does the conventional CTC method. We compared measured carbon yields, δ¹³C values and ¹⁴C activities between EA and CTC samples of carbon standards of various sample quantities. This newly developed EA system had low background ¹⁴C activity due to sample preparation; the background activity was similar to that observed for the CTC method. The EA system also showed high precision and accuracy for δ¹³C and ¹⁴C measurements. The EA sample data obtained from conventional quantities (>1 mg carbon) of standards showed good agreement with the results obtained by the CTC method and with the consensus values, though background contamination was detected for samples containing <0.5 mg carbon. Oxalic acid standards containing <0.5 mg carbon that were analyzed by the CTC method tended to have widely varying values of carbon yield, δ¹³C and ¹⁴C activity, suggesting that the CO₂ produced by combustion might have been prone to adsorption to an inner wall of the combustion tube, to CuO or to both, and that the CO₂ produced in the CTC method might have decomposed.     

Implementation of high-fidelity neutronics and thermal–hydraulic coupling calculations in HNET

To perform nuclear reactor simulations in a more realistic manner, the coupling scheme between neutronics and thermal-hydraulics was implemented in the HNET program for both steady-state and transient conditions. For simplicity, efficiency, and robustness, the matrixfree Newton/Krylov (MFNK) method was applied to the steady-state coupling calculation. In addition, the optimal perturbation size was adopted to further improve the convergence behavior of the MFNK. For the transient coupling simulat...     

The UV curing behavior of silicone modified polyacrylate resins containing tertiary amine structure

UV-radiation curing has become a well-accepted technology because of its distinct advantages mainly as environmental benign, efficiency, less energy consumption and mild curing condition. The free radical photopolymerizations have been based mainly on acrylate systems, which polymerize rapidly and can be adjusted with ease to modify materials with different properties for different applications.     

The Pre- and Post-Management of Code DWUCK4

P.D.Kung's DWUCK program is a main code to calculate direct reaction data with distorted-wave Born approximation and widely used in studying nuclear reaction mechanism and analysing experimental information, especially, calculating nuclear data. Unfortunately, the preparation of the input data is an arduous affair for multi-point of incident particle energy and multi-level calcu     

The property of Si/SiGe/Si heterostructure during thermal budget characterized by HRXRD

Si/SiGe/Si heterostructures grown by ultra-high-vacuum chemical vapor deposition (UHVCVD) were characterized by Rutherford backscattering/Channeling (RBS/C) together with high resolution X ray diffraction (HRXRD). High quality SiGe base layer was obtained. The Si/SiGe/Si heterostructures were subject to conventional furnace annealing and rapid thermal annealing with temperature between 750℃ and 910℃. Both strain and its relaxation degree in SiGe layer are calculated by HRXRD combined with elastic theory, which are never reported in other literatures. The rapid thermal annealing at elevated temperature between 880℃ and 910℃ for very short time had almost no influence on the strain in Si0.84Ge0.16 epilayer. However, high temperature (900℃@) furnace annealing for 1h prompted the strain in Si0.84Ge0.16 layer to relax.     

Actinide breeding and reactivity variation in a thermal spectrum ADSR – Part 1: Development of a lumped thermal reactor model

The beneficial properties of fast reactor systems in being able to both burn and breed actinides have led to renewed interest in this technology as a means of providing a more sustainable form of nuclear power production. However, despite significant investment over many years in the development of the technology, fast reactors have never been deployed in significant numbers. In view of the difficulties encountered in fast reactor development, enhancements to the existing, well proven light water reactor (LWR) technology may provide a more accessible path to improved sustainability.     

Track structure and energy deposition distribution of heavy ions in liquid water

Progress in theoretical research into track structure and energy deposition distribution of heavy ions in introduced,and some research results are given,such as a Monte Carlo model of heavy ion track structure calculation,frequency distribution of energy deposition inside a electron track and radial dose distribution around a heavy ion path.Moreover,research direction in future is also analysed.     

The level structure of ＆76Se from ^76Br γ—decay

The decay of ^76Br has been investigated for further study of the ^76Se levels.Gamma ray singles were measured with HpGe-NaI compton-suppressed spectrometer,Coincidence spectra were collected with two HpGe detectors coupled to a three-parameter system.There were 138 γ-rays observed.and 120 of these were fitted into 46 levels in ^76Se.37 γ-rays and 15 new energy levels were found for the first time.     

The Synergetic Effects of Hydrogen and Oxygen on the Strength and Ductility of Vanadium Alloys

A V4Ti alloy and several V4Cr4Ti alloys with different oxygen contents were studied on their tensile properties with the effect of hydrogen concentrations. The ductility of the alloys showed a successive decrease in a varied rate with an increased hydrogen concentration, while the ultimate tensile strength remained unchanged or even decreased for the high oxygen content alloy in spite of the occurrence of hardening in the low oxygen content alloy. Oxygen in the alloy causes grain boundary weakening, increasing the possibility of intergranular fractures and thus enhancing the hydrogen embrittlement. V4Ti showed a higher resistance to the hydrogen embrittlement as compared to the V4Cr4Ti alloys on a similar oxygen content level.