[en] Highlights: • Graphene produced from electrochemical exfoliation technique. • Cu–graphene–Ni diffusion couple produced and heated. • Negligible diffusion in Cu–graphene–Ni diffusion couple observed. Electrochemical exfoliation technique using the pyrophosphate anion derived from tetra sodium pyrophosphate was employed to produce graphene. As-synthesized graphene was then drop dried over a cold rolled Cu sheet. Ni coating was then electrodeposited over bare Cu and graphene–Cu substrates. Both substrates were then isothermally annealed at 800 °C for 3 h. WDS analysis showed substantial atomic diffusion in annealed Ni–Cu sample. Cu–graphene–Ni sample, on the other hand, showed negligible diffusion illustrating the diffusion barrier property of the graphene coating.

[en] Fabrication process of microporous filter supports of high permeability and more particularly tubular filter supports used to make porous barriers needed in isotope separation

[en] It is known that the small-world structure constitutes sufficient conditions to sustain cooperation and thus enhances cooperation. On the contrary, the network with a very long average distance is usually thought of as suppressing the emergence of the cooperation. In this paper we show that the fractal structure, of which the average distance is very long, does not always play a negative role in the organization of cooperation. Compared to regular networks, the fractal structure might even facilitate the emergence of cooperation. This mainly depends on the existence of locally compact clusters. The sparse inter-connection between these clusters constructs an asymmetric barrier that the defection strategy is almost impossible to cross, but the cooperation strategy has a not too small chance. More generally, the network need not to be a standard fractal, as long as such structures exist. In turn, when this typical structure is absent, the fractal structure will also suppress the emergence of the cooperation, such as the fractal configuration obtained by diluting a random tree-like network. Our findings also clarify some contradictions in the previous studies, and suggest that both removing and inserting links from/into a regular network can enhance cooperation. (paper)

[en] Study and characterization of gaseous diffusion barriers is obtained through the determination of several parameters representative of the quality of the samples: permeability, porosity, mean pore radius, pore distribution, specific area... Among the points which have to be known with accuracy, the separation efficiency S and the aerodynamic efficiency Z can be obtained by enrichment measurements made on argon isotopes. After a short definition of these factors of efficiency which characterize the functioning of a barrier in given conditions, the principle of the method of separation used for their experimental determination on benches working with argon is presented. A detailed description of the equipment, and a complete analysis of the mode of exploitation of the measurements are given

[en] Highlights: • The correlation between output power and the thickness of the diffusion barrier in the TEG was experimentally investigated. • Ni layers-adopted TEGs was prepared to confirm the correlation between the diffusion barrier and the output power. • The highest output power of 2.79 mW was generated from the TEG with thinnest Ni layer. • The diffusion barrier thickness-related behavior of electrical outputs was supported by the transmission line method. -- Abstract: The diffusion barrier layers in thermoelectric generators (TEGs) are widely used to improve their mechanical/thermal stabilities and energy generation performance; however, thickness dependence of diffusion barrier was rarely reported. In this study, we prepared Bi₂Te₃-based thermoelectric (TE) modules and Ni diffusion barrier with a thickness of 0–30 µm to investigate the correlation between the thickness of Ni layers and TE output performance. A TE module with 1 μm-thick Ni layer harvests a maximum output power of 2.79 mW under a temperature difference (ΔT) of 200 K, which is a higher value than that of a module without a diffusion barrier. Regarding the dependence of TE output performance on the diffusion barrier’s thickness, TEGs based on the thicker Ni layers showed lower output performance for all ΔT ranges compared with a 1 µm-Ni layer TEG. The degradation of TE conversion efficiency was related to the increment of contact resistance (R_c) with the thickness of the diffusion barrier. This Ni thickness-dependent R_c was explored using the transmission line method. The results from this study prove that the thickness of optimized diffusion barriers would maximize the output performance of TEGs, which could be used as a guide for improving the performance of TEGs.

[en] Within Phase 2 of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO), a Collaborative Project (CP), ROKI 'Proliferation Resistance: Acquisition/Diversion Pathway Analysis (PRADA)' has been carried out from 2007 to 2010, and has been used to develop a methodology for evaluating User Requirement (UR) 4 regarding the multiplicity and robustness of barriers against proliferation. This paper describes the main results of the PRADA project

[en] The effect of pre-existing barrier-type film on porous aluminum oxide film formation during anodization was investigated to control the uniform film growth rate. Initial potential fluctuations during anodization indicated that the breakdown of barrier-film is preceded before the porous formation and the induction time for the porous film growth increases with the increases of pre-existing film thickness. The porous film growth mechanism is lot affected by the presence of barrier film on aluminum surface. In parallel, uniform growth of barrier film underneath the porous structure was attained by two-step anodization processes

[en] We present a scheme improving the minimum-mode following method for finding first order saddle points by confining the displacements of atoms to the subset of those subject to the largest force. By doing so it is ensured that the displacement remains of a local character within regions where all eigenvalues of the Hessian matrix are positive. However, as soon as a region is entered where an eigenvalue turns negative all atoms are released to maintain the ability of determining concerted moves. Applying the proposed scheme reduces the required number of force calls for the determination of connected saddle points by a factor two or more compared to a free search. Furthermore, a wider distribution of the relevant low barrier saddle points is obtained. Finally, the dependency on the initial distortion and the applied maximal step size is reduced making minimum-mode guided searches both more robust and applicable

[en] The purpose of the present invention is a process and a device for making imprints on ceramic tubes and these ceramic tubes with imprints. It is known that in uranium enrichment processes by gaseous diffusion, microporous tubes are used to made the diffuser units used for the application of this isotope enrichment process. It is known that these microporous tubes are generally made in two stages. In a first stage, a macroporous ceramic tube called a ''support'' is made. In a second stage, an internal microporous deposit is made which makes it possible to obtain a tube called a ''barrier'' finally having the required porosity to apply the gaseous diffusion enrichment process. The present invention involves the first stage of the manufacturing process of the barriers and, more precisely, a step in the manufacturing process of the supports that makes it possible to improve the efficiency of these barriers

[en] The behaviors of barrier characteristics are analyzed for spherical-oblate systems over different configurations of colliding nuclei. For this purpose, we have extended our previous study [Phys. Rev. C 89 (2014) 054607], it is devoted to optimum “cold” and “hot” configuration] to analyze the same reaction systems in various configurations. The investigation on some chosen systems reveals that the barrier height and its position can be parameterized in times of the different orientations. (paper)