[en] In this paper Co-doped Al-substituted α-Ni(OH)₂ was prepared by a homogeneous precipitation method and its electrochemical behavior, in two kinds of electrolyte (7 M KOH solution and 7 M KOH saturated with Al(OH)₃), was investigated by galvanostatic charge-discharge method, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical properties of the commercial β-Ni(OH)₂ in both electrolyte was also studied in order to compare with that of α-Ni(OH)₂. The results show that Co-doped Al-substituted α-Ni(OH)₂ has the largest capacity in 7 M KOH solution (300 mAh g^-1). The addition of Al to KOH solution is harmful to the reversible capacity and cycle life of both α-Ni(OH)₂ and β-Ni(OH)₂. X-ray diffraction (XRD) patterns show that, for Co-doped Al-substituted α-Ni(OH)₂, its turbostratic structure maintains after cycles in both alkaline electrolyte, despite the interlayer distance becoming smaller. For β-Ni(OH)₂, however, γ-NiOOH species appeared after cycling in both electrolyte and its content is higher after cycling in 7 M KOH saturated with Al(OH)₃. And adding Al into KOH solution caused the decrease of solution conductivity and increased the apparent diffusion coefficient which is evidenced by electrochemical impedance spectroscopy

[en] In practice, customers can decide whether to buy an extended warranty or not, at the time of item sale or at the end of the basic warranty. In this paper, by taking into account the moments of customers purchasing two-dimensional extended warranty, the optimization of imperfect preventive maintenance for repairable items is investigated from the manufacturer's perspective. A two-dimensional preventive maintenance strategy is proposed, under which the item is preventively maintained according to a specified age interval or usage interval, whichever occurs first. It is highlighted that when the extended warranty is purchased upon the expiration of the basic warranty, the manufacturer faces a two-stage preventive maintenance optimization problem. Moreover, in the second stage, the possibility of reducing the servicing cost over the extended warranty period is explored by classifying customers on the basis of their usage rates and then providing them with customized preventive maintenance programs. Numerical examples show that offering customized preventive maintenance programs can reduce the manufacturer's warranty cost, while a larger saving in warranty cost comes from encouraging customers to buy the extended warranty at the time of item sale. - Highlights: • A two-dimensional PM strategy is investigated. • Imperfect PM strategy is optimized by considering both two-dimensional BW and EW. • Customers are categorized based on their usage rates throughout the BW period. • Servicing cost of the EW is reduced by offering customized PM programs. • Customers buying the EW at the time of sale is preferred for the manufacturer.

[en] Graphical abstract: - Highlights: • Graphene/nano-Au composite was synthesized by electrochemical co-reduction method in one step. • Glucose oxidase achieves direct electrochemistry on the graphene/nano-Au composite film. • The glucose biosensor shows a high sensitivity of 56.93 μA mM"−"1 cm"−"2 toward glucose. • Glucose was detected with a wide linear range and low detection limit. - Abstract: A simple, green and controllable approach was employed for electrochemical synthesize of the graphene/nano-Au composites. The process was that graphene oxide and HAuCl_4 was electrochemically co-reduced onto the glassy carbon electrode (GCE) by cyclic voltammetry in one step. The obtained graphene/nano-Au/GCE exhibited high electrocatalytic activity toward H_2O_2, which resulted in a remarkable decrease in the overpotential of H_2O_2 electrochemical oxidation compared with bare GCE. Such electrocatalytic behavior of the graphene/nano-Au/GCE permitted effective low-potential amperometric biosensing of glucose via the incorporation of glucose oxidase (GOD) with graphene/nano-Au. An obvious advantage of this enzyme electrode (graphene/nano-Au/GOD/GCE) was that the graphene/nano-Au nanocomposites provided a favorable microenvironment for GOD and facilitated the electron transfer between the active center of GOD and electrode. The immobilized GOD showed a direct, reversible redox reaction. Furthermore, the graphene/nano-Au/GOD/GCE was used as a glucose biosensor, displaying a low detection limit of 17 μM (S/N = 3), a high sensitivity of 56.93 μA mM"−"1 cm"−"2, acceptable reproducibility, very good stability, selectivity and anti-interference ability

[en] Highlights: • CuO-rGO nanocomposites was synthesized with a facile, green and effective chemical method. • The nonenzymatic modified electrode achieved electrocatalytic oxidation towards glucose. • The glucose sensor shows a high sensitivity of 2221 μA mM⁻¹ cm⁻² towards glucose. • Glucose was detected with a wide linear range and low detection limit. - Abstract: A novel, stable and sensitive non-enzymatic glucose biosensor based on nanocomposites of copper oxide (CuO) and the reduced graphene oxide (rGO) was developed. A facile, green and effective chemical method was employed to synthesize the CuO-rGO nanocomposites in a mixture solution of water-isopropanol. During the synthesis process, isopropanol acted as both solvent and reductant. CuO nanoparticles were successfully decorated onto the graphene oxide (GO) sheets through electrostatic force and hydrolysis reaction. Meantime, GO could be partly reduced to the rGO without any addition of strong reduction agents. The information on the structure and topology of as-prepared CuO-rGO nanocomposites was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and its electrochemical catalytical performance was also studied. The results indicated that CuO-rGO nanocomposites could display a synergistic effect of rGO sheets and CuO nanoparticles towards the electro-oxidation of glucose in the alkaline solution, leading to a remarkable decrease in the overpotential of the glucose oxidation. At the applied potential of 0.4 V, the CuO-rGO film modified glassy carbon electrode (CuO/rGO/GCE) presented a high sensitivity of 2221 μA mM⁻¹ cm⁻² and a wide linear range from 0.4 μM to 12 mM towards glucose with good selectivity and stability

[en] Raman spectroscopy has been used to characterize uranium hydride and deuteride. Raman shifts of UH_3 and UD_3 are evident to be inversely proportional to the square root of the mass of hydrogen isotope. The typical Raman peaks of UH_3 and UD_3 can be characterized by the mass difference of hydrogen isotope for one another. In addition, Raman peaks of uranium hydride and deuteride are identified to be at 725 and 938 cm"−"1 for UH_3 and 518 and 669 cm"−"1 for UD_3, respectively

[en] To study the behavior of hydrogen corrosion at the surface of U, U–2.5 wt%Nb alloy and U–5.7 wt%Nb, a gas–solid reaction system with an in situ microscope was designed. The nucleation and growth of the hydride of the alloy were continuously observed and recorded by a computer. The different characteristics of the hydrides on U metal and U–2.5 wt%Nb showed that the later alloy is more susceptible to hydrogen corrosion than the former. The growth rate of hydride of U–2.5 wt%Nb, calculated by measuring the perimeter of the hydride spots recorded by the in situ microscope, exhibited a reaction temperature dependency in the range of 40–160 °C, for pressure of 0.8 × 10⁵ Pa. An Arrhenius plot for growth rate versus temperature yielded activation energy of 24.34 kJ/mol for the hydriding of U–2.5 wt%Nb alloy. The maximum hydriding rate was obtained at 125 °C, whose thermodynamics reason was discussed

[en] The paper proposes a prediction and verification methodology that provides an independent verification of declared small modular reactor (SMR) operating conditions, and therefore fissile material content, for safeguards purposes. This methodology consists of high-fidelity simulations of “indicating parameters” (e.g., neutron flux profiles outside the primary reactor system) coupled with off-line neutron dosimetry of retrievable verification specimens. The methodology is intended to detect erroneous reporting and/or undeclared activities during reactor operation, through discrepancies between simulated and measured indicating parameters, confirmed by offline dosimetry of verification specimens. The indicating parameters are simulated using the Monte Carlo reactor physics code SERPENT. The proposed prediction and verification methodology is demonstrated on a small modular fluoride-salt-based molten salt reactor (sm-FMSR) and a microsized high-temperature gas-cooled reactor (m-HTGR). The results show that the flux profiles outside of the reactor primary system, which are unique in value and trend for different SMR designs, are effective indicating parameters for reactor operating conditions. With verified operating conditions, one of the most important nuclear safeguards parameters, the fissile material content in the reactor, can be determined. (author)

[en] In support of the Pan-Canadian Small Modular Reactor (SMR) roadmap activities, radionuclide inventory calculations for structural materials of various SMR types are performed. The calculations provide essential data for improving the understanding of reactor safety, radioactive material management, and environmental impacts. The Monte Carlo code SERPENT is used to model five major types of SMR, based on the latest published design data, to obtain neutron flux distributions in space and energy as functions of operating schedule, and the SCALE/ORIGEN code is then used for time-dependent neutron activation and decay calculations. Radionuclide inventories have been comprehensively estimated for principal structures of five SMRs: integral pressurized water reactor (iPWR), molten salt reactor (MSR), high-temperature gas-cooled reactor (HTGR), lead-cooled fast reactor (LFR), and heat pipe based reactors. The primary contributing reactor components, the dominating radionuclides to the total activity, and the radioactivity evolution with time after reactor shutdown, are discussed. (author)

[en] Highlights: • High-quality PMN-PT 90/10 RFE thin films were prepared by RF magnetron sputtering. • The maximum discharged density of 31.3 J/cm"3 was obtained in the 750-nm-thick film. • PMN-PT RFE films might be a promising material for energy-storage application. - Abstract: 0.9Pb(Mg_1_/_3Nb_2_/_3)O_3-0.1PbTiO_3 (PMN-PT 90/10) relaxor ferroelectric thin films with different thicknesses were deposited on the LaNiO_3/Si (100) by the radio-frequency (RF) magnetron sputtering technique. The effects of thickness and deposition temperature on the microstructure, dielectric properties and the energy-storage performance of the thin films were investigated in detail. X-ray diffraction spectra indicated that the thin films had crystallized into a pure perovskite phase with a (100)-preferred orientation after annealed at 700 °C. Moreover, all the PMN-PT 90/10 thin films showed the uniform and crack-free surface microstructure. As a result, a larger recoverable energy density of 31.3 J/cm"3 was achieved in the 750-nm-thick film under 2640 kV/cm at room temperature. Thus, PMN-PT 90/10 relaxor thin films are the promising candidate for energy-storage capacitor application

[en] Crystals grown from Bi-Sr-Ca-Cu-O system may have different contents of Sr and Ca when varying the ratio of Sr/Ca in the starting composition. The Sr/ Ca ratio in crystals has important influence on the superconducting property of Bi-Sr-Ca-Cu-O crystal. The lattice parameter c increased from 30.60A to 30.01A and Tc(zero) increased from 84K to 90K with the increasing of Sr/Ca ratio from 2:1 to 3:1 accordingly. This result has shown its importance for understanding high-Tc superconducting phenomenon in Bi-Sr-Ca-Cu-O system further. (author). 5 refs., 3 figs., 1 tab