Colloidal stability of Ni(OH)₂ in water and its dispersion into a ceramic matrix from the reaction media to obtain Ni/Al₂O₃ materials

Ni/Al₂O₃ composites have been fabricated by slip casting of concentrated Ni(OH)₂/Al₂O₃ suspensions and subsequent in situ reduction to metallic nickel during sintering. For that, the synthesis assisted by ultrasound of both α- and β-Ni(OH)₂ polymorphs, as well as their colloidal stability, have been studied. The structural differences between both polymorphs have been thoroughly studied by means of XRD, FTIR, DTA-TG, SSA, SEM and TEM, in order to optimize the starting suspensions. This way, the IEP of both polymorphs have been established (9.7 y 12 for β- and α-Ni(OH)₂, respectively), as well as the optimal content of an anionic dispersant (PAA) to stabilize the particles (0.8 wt. % for beta phase and 3.0 wt. % for alpha phase). Three different Ni/Al₂O₃ composites, with a high dispersion degree of the metallic phase, have been obtained considering the potential vs. particles distance curve of the Ni(OH)₂, and their structure has been discussed in terms of the strength of the agglomerates and/or aggregates of the Ni(OH)₂.La obtención de materiales compuestos Ni/Al₂O₃ se ha llevado a cabo mediante colaje en molde de escayola de suspensiones concentradas de Ni(OH)₂/Al₂O₃ y su posterior reducción in situ para obtener la fase metálica. Para ello, se ha estudiado la síntesis asistida por ultrasonido de los polimorfos α- y β-Ni(OH)₂, así como su comportamiento coloidal en medio acuoso. Las diferencias estructurales entre ambos polimorfos han sido estudiadas en detalle mediante XRD, FTIR, ATD-TG, SSA, MEB y MET, para poder optimizar las suspensiones de partida. De esta manera, se ha establecido el PIE de ambos polimorfos (9.7 y 12 para las fases β- y α-Ni(OH)₂, respectivamente), así como el contenido óptimo de un dispersante aniónico (PAA) para la estabilización de las partículas (0.8 % p/p para la fase beta y 3.0 % p/p para la fase alfa). Tres materiales compuestos Ni/Al₂O₃ diferentes, con un alto grado de dispersión de la fase metálica, han sido obtenidos en función de la curva de potenciales de interacción frente a distancia entre partículas del Ni(OH)₂ y su estructura se ha discutido en función de la fortaleza de los aglomerados y/o agregados del Ni(OH)₂

Can Clinical Pathways be Developed to Offer Assistance in Child Care Cases?

Clinical and care pathways are increasingly being used to help with decision-making in various areas of health and social care. The value of these pathways is that they provide a standard approach to offering care, help maintain quality of delivery, and control cost. This paper reports on the first step in developing a pathway which may assist in the very difficult process of deciding the level of contact to birth parents of children after their removal from their care. The use of such a pathway in this area is fraught with difficulty, but if successful may help practitioners achieve the arrangements that are in the best interests of the child

Electrophoretic Deposition of Chitosan/h-BN and Chitosan/h-BN/TiO2 Composite Coatings on Stainless Steel (316L) Substrates

This article presents the results of an experimental investigation designed to deposit chitosan/hexagonal boron nitride (h-BN) and chitosan/h-BN/titania (TiO2) composites on SS316L substrates using electrophoretic deposition (EPD) for potential antibacterial applications. The influence of EPD parameters (voltage and deposition time) and relative concentrations of chitosan, h-BN and TiO2 in suspension on deposition yield was studied. The composition and structure of deposited coatings were investigated by FTIR, XRD and SEM. It was observed that h-BN and TiO2 particles were dispersed in the chitosan matrix through simultaneous deposition. The adhesion between the electrophoretic coatings and the stainless steel substrates was tested by using tape test technique, and the results showed that the adhesion strength corresponded to 3B and 4B classes. Corrosion resistance was evaluated by electrochemical polarization curves, indicating enhanced corrosion resistance of the chitosan/h-BN/TiO2 and chitosan/h-BN coatings compared to the bare stainless steel substrate. In order to investigate the in-vitro inorganic bioactivity, coatings were immersed in simulated body fluid (SBF) for 28 days. FTIR and XRD results showed no formation of hydroxyapatite on the surface of chitosan/h-BN/TiO2 and chitosan/h-BN coatings, which are therefore non bioactive but potentially useful as antibacterial coatings

Electrophoretic deposition of ZnO/alginate and ZnO-bioactive glass/alginate composite coatings for antimicrobial applications

Two organic/inorganic composite coatings based on alginate, as organic matrix, and zinc oxide nanoparticles (n-ZnO) with and without bioactive glass (BG), as inorganic components, intended for biomedical applications, were developed by electrophoretic deposition (EPD). Different n-ZnO (1–10 g/L) and BG (1–1.5 g/L) contents were studied for a fixed alginate concentration (2 g/L). The presence of n-ZnO was confirmed to impart antibacterial properties to the coatings against gram-negative bacteria Escherichia coli, while the BG induced the formation of hydroxyapatite on coating surfaces thereby imparting bioactivity, making the coating suitable for bone replacement applications. Coating composition was analyzed by thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) analyses. Scanning electron microscopy (SEM) was employed to study both the surface and the cross section morphology of the coatings. Polarization curves of the coated substrates made in cell culture media at 37 °C confirmed the corrosion protection function of the novel organic/inorganic composite coatings.by Luis Cordero-Arias, S. Cabanas-Polo, O. M. Goudouri, Superb K. Misra, J. Gilabert, E. Valsami-Jones, E. Sanchez, S. Virtanen and A. R. Boccaccin

Microstructural and electrical characterization of Mn-Co spinel protective coatings for solid oxide cell interconnects

Electrophoretic deposition, thermal co-evaporation and RF magnetron sputtering methods are used for the preparation of Mn-Co based ceramic coatings for solid oxide fuel cell steel interconnects. Both thin and relatively thick coatings (1–15 μm) are prepared and characterised for their potential protective behaviour. Mn-Co coated Crofer22APU samples are electrically tested for 5000 h at 800 °C under a 500 mA cm−2 current load to determine their Area Specific Resistance increase due to a growing chromia scale. After tests, samples are analysed by scanning and transmission electron microscopy. Analysis is focused on the potential chromium diffusion to or through the coating, the oxide scale thickness and possible reactions at the interfaces. The relationships between the coating type, thickness and effectiveness are reviewed and discussed. Out of the three Mn-Co coatings compared in this study, the one deposited by electrophoretic deposition presents the best protection against Cr diffusion and offers long term stability