Performance of hybrid buffer Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) layers doped with plasmonic silver nanoparticles

We compare the performance of a typical hole transport layer for organic photovoltaics (OPVs), Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) thin film with a series of PEDOT:PSS layers doped with silver (Ag) nanoparticles (NPs) of various size distributions. These hybrid layers have attracted great attention as buffer layers in plasmonic OPVs, although there is no report up to date on their isolated performance. In the present study we prepared a series of PEDOT:PSS layers sandwiched between indium tin oxide (ITO) and gold (Au) electrodes. Ag NPs were deposited on top of the ITO by electron beam evaporation followed by spin coating of PEDOT:PSS. Electrical characterization performed in the dark showed linear resistive behavior for all the samples; lower resistance was observed for the hybrid ones. It was found that the resistivity of the samples decreases with increasing the particle's size. A substantial increase of the electric field between the ITO and the Au electrodes was seen through the formation of current paths through the Ag NPs. A striking observation is the slight increase in the slope of the current density versus voltage curves when measured under illumination for the case of the plasmonic layers, indicating that changes in the electric field in the vicinity of the NP due to plasmonic excitation is a non-vanishing factor

Pectus excavatum and scoliosis: a review about the patient’s surgical management

Although Nuss procedure is performed with satisfactory results, there has been a controversy in the literature regarding the effect of a Nuss procedure on the spine. This review article aims to perform an updated overview of the literature about the effect of pectus excavatum correction at the spine and the management of patients with both pectus excavatum and scoliosis. Although acquired scoliosis has been rarely reported after a Nuss procedure, studies show that the Nuss procedure can have a beneficial effect in mild coexisting scoliosis especially when it is performed during the adolescence. The management of cases presented with both pectus excavatum and scoliosis depends on the severity of pre-operative scoliosis and demands detailed evaluation of the spine pre and postoperatively. In the rare condition of post-operative scoliosis following a Nuss procedure, the removal of the metallic bar and conservative measures may have satisfactory results on the spine. © 2020, The Japanese Association for Thoracic Surgery

Mechanically induced waves in metallic glass foils

International audienceThe response of vitrified metallic arc foils under normal load is studied. Application of normal load on an initial arc shaped vitrified metallic foil is followed by multiplication of the initial arc. A sinusoidal mathematical expression can be used for the description of the produced harmonic undulations. The number of the formed waves increases as the displacement increases. Therefore, this undulatory behavior of the vitrified foils can be exploited as a flat spring with multiple spring constants. For comparison crystalline foils were tested. The enormous elastic region of vitrified alloys allows this undulatory response to occur extensively while plastic deformation is unavoidable when crystalline foils are used. Exploiting the metallic glass characteristics, the predefined extrem a positions of the formed undulations and the mechanical characteristics of the vitrified foils a new type of electromechanical switch is suggested. (c) 2015 Elsevier Ltd. All right

Nanoporous titanium obtained from a spinodally decomposed Ti alloy

International audiencePorous noble metal surfaces were produced by gold-smiths in ancient times by dealloying. These processes lead to the formation of gold or other noble metal rich layers. Such dealloying occurs by corrosion as the most electro-chemically active elements dissolve and the more noble elements aggregate into clusters by phase separation (spinodal decomposition). Here we report results from an alternative path to nanoporosity where the structure patterns and length scales are first fixed in the bulk by high temperature spinodal decomposition followed by chemical dissolution of one of the component products of the phase-separation. The process may be used to form nanoporous titanium for biochemical applications. (C) 2015 Elsevier Inc. All rights reserved

Structure and deformation behavior of Zr-Cu thin films deposited on Kapton substrates

International audienceIn the present work we study Zr-Cu thin films deposited on flexible Kapton substrates by magnetron sputtering. The morphology of "as-grown" films had complex hierarchical structure with size of building blocks from similar to 14 nm to similar to 3 mu m. The larger was the size of hierarchical unit, the thicker was the boundary separating it from adjacent units of similar size. During the bending tests cracks propagated predominantly between the largest blocks, indicating the negative impact of the wide interfaces on the mechanical properties of thin films. Crystallization shrinkage and thermal contraction were described as factors that contribute to the development of the boundaries

Ab-initio and experimental study of phase stability of Ti-Nb alloys

International audienceA systematic theoretical and experimental study concerning the crystallographic structure and electronic properties of Ti-xNb (x 18.75 at% the beta-phase is favoured against all other crystallographic structures in line with the experimental results. Interestingly, at high Nb content the alpha' and omega hexagonal phases become unstable due to the electronic band filling close to the Fermi level E-F, which is mainly due to Nb-p and Ti-d antibonding hybridizations. On the contrary, in the cubic beta-Ti-25Nb (at%) the depletion of the occupied electronic states at the EF occurs mainly due to Nbd and Ti-d bonding interactions, resulting in a stable beta-TiNb structure. These data could enlighten the electronic origin of the Ti-Nb phase stability, thus, may contribute to the design of beta stabilized low moduli Ti-based alloys suitable for load-bearing biomedical applications. (C) 2016 Elsevier B. V. All rights reserved