[en] The work presented here was devoted to the modelling and simulation of the dynamic response of lead cables of Inconel self-powered neutron detectors in a CANDU power reactor. The main goal was to develop a semi-empirical dynamic model of the Inconel lead-cables in Ontario Power Generation’s Darlington Nuclear Generation Station (NGS) able to simulate the lead cables’ response to arbitrary neutron-flux transients. A secondary goal was to compare lead-cable dynamic characteristics evaluated in the Darlington reactor to lead-cable characteristics previously evaluated in AECL’s NRU reactor. A Simulink model of the lead cable was developed. The model’s parameters were obtained by fitting simulation results to measured lead-cable signals acquired during reactor shutdown. The functionality of the Simulink model was demonstrated for arbitrary neutron flux transients and simulation results were found to agree within 1.2% with measurements for reactor trip transients. At the same time, differences between the dynamic characteristics (e.g. prompt fraction) of lead cables in a power reactor (Darlington) and research reactor (NRU) were identified. A tentative explanation of those differences was formulated. A comprehensive elucidation of the reasons for the observed differences will have to be addressed by future studies. (author)

[en] The effect of substitution Ti for Co in Sm₂Co_17-xTi_x compounds with 0≤x≤1.13 on the structure and magnetic properties have been investigated by X-ray diffraction (XRD) and magnetic measurements. The XRD patterns show that all compounds investigated are single phase with the rhombohedral Th₂Zn₁₇-type of structure. Substitution of Ti for Co leads an expansion of the unit cell. The saturation magnetization M_s and Curie temperature T_C are found to decrease with increasing Ti concentration. The XRD patterns of magnetically aligned samples indicate that the easy magnetization direction (EMD) of all compounds is along the c-axis at room temperature. The anisotropy field B_a at 5 K and room temperature is found to increase with increasing Ti concentration, attaining a maximum value at about x=1.0

[en] Among ceramic/metal (C/M) joining technologies, the active filler metal method has been studied extensively due to the simple brazing process and excellent joint strength. Active metal elements, typically Ti, are intentionally added to braze alloys to enhance the formation of reaction products between the ceramic and the braze metal at the C/M interface. In the brazing of Al₂O₃ with the Ag-Cu-Ti filler metal, reaction products such as γ-TiO, Cu₂(Ti, Al)₄O, Ti₃(Cu_0.76Al_0.18Sn_0.06)₃O were found, while products such as Ti₅Si₃ and TiN formed in the brazing of Si₃N₄. The presence of reaction layers at the C/M interface influences the interface strength in a complex way. In Cu/Al₂O₃, Co/Al₂O₃, Ni/Al₂O₃, and Cu/diamond systems, maxima of joint strength were observed at some intermediate Ti addition, while the flexural strength decreased substantially with the thickening of the TiO layer in a ZrO₂/Ag-Cu-Sn-Ti system. Thus, composition of the braze alloy (particularly, the content of the active metal), process conditions such as brazing temperature and time, microstructure and mechanical properties of reaction products at the C/M interfaces, interfacial chemistry, and residual stress are primary factors to be studied in order to understand the strengths of the C/M interfaces systematically. In the present and the following papers, evolutions of interfacial microstructures at various brazing conditions, and corresponding interface strengths are reported, respectively, for a ZrO₂/Ag-Cu-Al-Ti system

[en] This paper presents an automatic performance estimation scheme of conceptual temperature control system with multi-heater configuration prior to constructing the physical system for achieving rapid validation of the conceptual design. An appropriate low-order discrete-time model, which will be used in the controller design, is constructed after determining several basic factors including the geometric shape of controlled object and heaters, material properties, heater arrangement, etc. The proposed temperature controller, which adopts the multivariable GPC (generalized predictive control) scheme with scale factors, is then constructed automatically based on the above model. The performance of the conceptual temperature control system is evaluated by using a FEM (finite element method) simulation combined with the controller.

[en] Polymerases are protein enzymes that move along nucleic acid chains and catalyze template-based polymerization reactions during gene transcription and replication. The polymerases also substantially improve transcription or replication fidelity through the non-equilibrium enzymatic cycles. We briefly review computational efforts that have been made toward understanding mechano–chemical coupling and fidelity control mechanisms of the polymerase elongation. The polymerases are regarded as molecular information motors during the elongation process. It requires a full spectrum of computational approaches from multiple time and length scales to understand the full polymerase functional cycle. We stay away from quantum mechanics based approaches to the polymerase catalysis due to abundant former surveys, while addressing statistical physics modeling approaches along with all-atom molecular dynamics simulation studies. We organize this review around our own modeling and simulation practices on a single subunit T7 RNA polymerase, and summarize commensurate studies on structurally similar DNA polymerases as well. For multi-subunit RNA polymerases that have been actively studied in recent years, we leave systematical reviews of the simulation achievements to latest computational chemistry surveys, while covering only representative studies published very recently, including our own work modeling structure-based elongation kinetic of yeast RNA polymerase II. In the end, we briefly go through physical modeling on elongation pauses and backtracking activities of the multi-subunit RNAPs. We emphasize on the fluctuation and control mechanisms of the polymerase actions, highlight the non-equilibrium nature of the operation system, and try to build some perspectives toward understanding the polymerase impacts from the single molecule level to a genome-wide scale. (topical review)

[en] A comparative study of the mutual separation characteristics and mechanism was made for neighboring rare-earth elements La, Ce, Pr, and Nd from their binary chloride mixtures and oxide mixtures using a chemical vapor-transport reaction under a suitable temperature and pressure gradient. The separation factors, expressed as the atomic ratios for the resulting chlorides, were observed within 6 h up to 21.4 for La:Ce, ≥ 100 for Pr:Ce, and 1.84 for Pr:Nd from the oxide mixtures; however, they were only 12.3 for La:Ce, 5.79 for Pr:Ce, and 1.32 for Pr:Nd from the chloride mixtures under identical reaction conditions, using AlCl₃ as the sole complex former. It was also observed for the mutual separation from the oxide mixtures that the separation factors increased when KCl was added as another complex former, but decreased several times when either without chlorine in the carried gas, or without active carbon in the raw material, or under a poor vapor-transport condition. These results provide evidence that this reaction for the oxide mixtures would mainly be the combination of a carbothermic reduction-chlorination of the oxides, complexation of the chlorides, and transportation of the vapor complexes. (author)

[en] This project aims to develop an effective field system and database structure by analyzing the quantitative and qualitative geological data and establish its application plan. The contents and the scope of this study are as follows : developing a geo-information software, producing digital data from previous works and information-geological, age dating, trench information, topographic and geologic maps, establish a home page

[en] Density functional theory in combination with polarizable continuum model is used to investigate one- and two-photon absorption (TPA) as well as emission properties of newly synthesized photoinduced electron transfer (PET)-based two-photon fluorescent probes QNO and LNO in the absence and presence of nitric oxide (NO). Both fluorescent intensity and TPA are enhanced when QNO (LNO) reacts with NO, which theoretically proves that the compounds QNO and LNO are promising two-photon fluorescent probes for NO. Moreover, QNO is demonstrated to be preferable because of its superior fluorophore. Analysis of molecular orbitals is presented to explore responsive mechanism of QNO (LNO) for NO.

[en] The present study has been performed to select the osmotic tolerant lines using polyethylene glycol (PEG 6000)through an in vitro and in vivo mutagensis with a gamma-ray. During the screening, we selected three mutant lines that seemed to confer elevated osmotic tolerance in high concentrations of PEG 6000. Fruits of these mutants (Os-HK101, Os-HK102 and Os-HK103) were those of the wild type. Also the chlorophyll contents were few decreased more in the three mutant lines than the WT plants. Our results suggest that the Os-HK101 is characterized as osmotic stress tolerance considering the sugar concentration and lycopine content. It is expected that the result of this study can be used for breeding more competitive species with respect to contents in sugar or functional chemicals from the selected osmotic resistant lines

[en] The coexisting phases in the Nd-Fe-B light rare-earth-transition metal permanent alloys are identified with electron diffraction and lattice imaging. The major phase is confirmed to be a tetragonal intermetallic phase with space group P4₂/mnm. The f.c.c. Nd-rich phase has an ordered structure while the tetragonal B-rich phase is an one-dimensional incommensurate structure. A model is suggested for the origin of this one-dimensional incommensuracy. (author)