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In this study, hydroxyapatite (HA) nanoparticles (~120 nm, 3 vol %) are incorporated within a subsurface layer based on commercial pure titanium using multi-step friction-stir processing (FSP) to fabricate an CP-Ti/HA surface nanocomposite. A combination of electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM) analyses are used to developed a correlation between microstructural features and crystallographic texture formed by material flow and dynamic restoration phenomena in the processed titanium versus CP-Ti/HA surface nanocomposite. An equiaxed ultra-fine grained structure with a mean size <1.4 μm forms on the surface of both samples caused by N and O absorption into the structure of the titanium substrate during high-temperature severe plastic deformation via FSP. The annealed BM does not contain any preferred orientation and its texture is completely random. However, the scenario is significantly altered by FSP treatment due to martensitic phase transformation as well as the absorption of impurities on the titanium surface, the incorporation of HA inclusions, and thermo-mechanical treatment. This results in new crystallographic textures consisting of weak shear and strong prismatic P -fiber dominant components on the surface and center of the processed zone respectively. • A new Ti-matrix surface nanocomposite was prepared by FSP treatment. • A fine recrystallized equiaxed grain structure with the average size of ~1.4 μm formed in the SZ. • A strong prismatic P -fiber texture component induced by incorporation of HA nanoparticles. • A considerable mechanical strength improvement of up to ~30% was obtained by FSP modification. • Complex structure of HA and its decomposition deteriorated the tensile strength of nanocomposite, despite of considerable hardening. [ABSTRACT FROM AUTHOR]

Abstract: Due to a variety of technical problems encountered in advanced mechanical and aerospace industries, traditional reverse engineering in which only a copy of the old component using CAD/CAM systems is developed is less effective. As a matter of fact, re-engineering methodologies should be used to optimize the component/sub-system design concerning new materials and advanced manufacturing technologies often employed in such industries. This may cause to achieve a cheaper, lighter component together with a higher reliability. This paper describes an integrated re-engineering plan for the replacement of aerospace components/sub-systems. As a case study, re-engineering of a rupture disk used as a safety device in a turbofan jet engine is conducted. A new material and a new manufacturing process are suggested for this component to fit in the design with available low cost material and manufacturing process. The obtained results show the effectiveness of the proposed plan. [Copyright &y& Elsevier]

Hydrogen sulphide (H2S) has been recently proposed as a transmitter in the brain and peripheral tissues. Its role in the gastrointestinal tract is still unknown despite some data which suggest an involvement mediating smooth muscle relaxation. The aim of this study was to investigate the effect of this gas on intestinal segments from mouse jejunum and colon, and muscular strips from the human and rat colon. In isolated segments of mouse colon and jejunum, bath applied sodium hydrogen sulphide (NaHS) (a H2S donor) caused a concentration-dependent inhibition of spontaneous motor complexes (MCs) (IC50 121 μmol L−1 in the colon and 150 μmol L−1 in the jejunum). This inhibitory effect of NaHS on MCs was (i) unaffected by tetrodotoxin (TTX), capsaicin, pyridoxal-phosphate-6-azophenyl-2′,4′-disulfonate and N-nitro-l-arginine suggesting a non-neural effect and (ii) significantly reduced by apamin 3 μmol L−1. NaHS concentration-dependently inhibited the spontaneous motility in strips from human colon (IC50 261 μmol L−1) and rat colon (IC50 31 μmol L−1). The inhibitory effect of NaHS on colonic strips was (i) unaffected by the neural blocker TTX (1 μmol L−1) with IC50 183 μmol L−1 for the human colon and of 26 μmol L−1 for the rat colon and (ii) significantly reduced by glybenclamide (10 μmol L−1), apamin (3 μmol L−1) and TEA (10 mmol L−1) with IC50 values of 2464, 1307 and 2421 μmol L−1 for human strips, and 80, 167 and 674 μmol L−1 for rat strips respectively. We conclude that H2S strongly inhibits in vitro intestinal and colonic motor patterns. This effect appears to be critically dependent on K channels particularly apamin-sensitive SK channels and glybenclamide-sensitive K (ATP) channels. [ABSTRACT FROM AUTHOR]

To improve the efficiency of electrochemical processes for environmental remediation, we present a new type of hybrid nanomaterials based on leaf-like copper-based quaternary transition metals and spongy monolayer graphene. To demonstrate the functionality of the hybrid electrocatalyst, fast and competent electrooxidation of water and glucose is shown. The mechanism of improved catalysis is ascribed to the synergetic catalytic effect of quaternary Cu-Ni-Fe-Co alloy with dendritic morphology along with the highly conductive and spongy structure of the graphene monolayer. It is shown that water oxidation can be performed at a low overpotential of 315 mV to reach a current denisty of 100 mA cm-2 and a low Tafel slope of 63.06 mV dec−1. Fast and sensitive amperometric detection of glucose at low concentrations (≥1.3 μM; 4153 μA mM−1 cm−2) in alkaline solutions is also presented. The compelling performance of the hybrid catalyst as compared with many noble-metal and non-precious metal electrocatalysts for water oxidation and electrochemical sensing is reported. [Display omitted] [ABSTRACT FROM AUTHOR]