Protective nature of nano-TiN coatings shaped by EPD on Ti substrates

The hardness and corrosion resistance of TiN coatings, processed by Electrophoretic Deposition (EPD) to cover polished and unpolished Ti substrates, have been evaluated. A deposition time of 5 min has been enough to obtain a cohesive layer of 7–8 μm in thickness. The coatings were thermally treated in vacuum atmosphere at 1200 °C for 1 h with heating and cooling rates of 5 °C min−1. The surfaces have been covered homogeneously optimizing the properties of the Ti substrates. Uniform and dense TiN coatings have been obtained onto polished substrates, while on unpolished Ti the nitrogen diffuses toward the substrate, moderately dissolving TiN coating. The nanohardness values of the polished samples have been increased from 2.8–4.8 GPa up to 6.5–8.5 GPa. Besides, the corrosion current density has been reduced more than one order of magnitude obtaining a protective efficiency of 82%. These values have been compared with other works in literature where authors used complex and costly processing techniques, demonstrating the strong impact of the colloidal processing over the specific properties of the material

Effect of surface modifiers on the nanoparticles electro-driven assembly

Understanding the colloidal behavior of particles is mandatory to prepare stable and disperse suspensions suitable for EPD. Up today, most of the proposed models for the EPD kinetics have been formulated considering the electrophoresis process, where depositing features are quantified by the sticking factor, a probabilistic and empiric parameter. Proposed models have demonstrated that interparticles forces are also the clue to understand the way in which particles compact on the electrode under the influence of an electric field in an electrostatically stabilized suspension. Empirically in those systems, the morphology, the crystallography and the reactivity of the particles, determine the charge distribution in their surfaces, while the ionic strength modulates the charge density. However, new perspectives of particles assembly verified that in suspensions stabilized by an electrosteric mechanism, under similar electric conditions, changes in nature, length and ionization strength of surface modifiers or ligands determine the interaction forces among nanoparticles, resulting in an effective tool to manage nanoparticles flocculation and hence kinetics and ordering during the film growth. This fact has been specifically proved in the electrophoretic deposition of nanoplatelets or in the spatial orientation of nanocrystals. In this paper, we will discuss the literature that evidences how the surface modifiers not only define the deposition rate, but they also determine the deposition behavior and the final microstructure of the coating. Particularly the Layer-by-Layer (LbL) technology, understood as the alternate absorption of cationic and anionic polymers onto the particle surface, will be shown as an example of the compaction tailoring in 3D ceramic electrodes for supercapacitor manufacturing

Effect of surface modifiers on the nanoparticles electro-driven assembly

Understanding the colloidal behavior of particles is mandatory to prepare stable and disperse suspensions suitable for EPD. Up today, most of the proposed models for the EPD kinetics have been formulated considering the electrophoresis process, where depositing features are quantified by the sticking factor, a probabilistic and empiric parameter. Proposed models have demonstrated that interparticles forces are also the clue to understand the way in which particles compact on the electrode under the influence of an electric field in an electrostatically stabilized suspension. Please click on the link below for the full content

Manufacturing Tin Films Through A One‐Step Processing Method: Shaping and Sintering by EPD

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Modelling of Electrophoretic Deposition (EPD) of soft particles and experimental verification

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Use of failure-to-rescue after emergency surgery as a dynamic indicator of hospital resilience during the COVID-19 pandemic: A multicenter retrospective propensity score-matched cohort study

Coronavirus; Operacions quirúrgiques; EpidemiologiaCoronavirus; Intervenciones quirúrgicas; EpidemiologíaCoronavirus; Surgical procedures; EpidemiologyBackground: Surgical failure-to-rescue (FTR, death rate following complications) is a reliable cross-sectional quality of care marker, but has not been evaluated dynamically. We aimed to study changes in FTR following emergency surgery during the COVID-19 pandemic. Material and methods: Matched cohort study including all COVID-19-non-infected adult patients undergoing emergency general surgery in 25 Spanish hospitals during COVID-19 pandemic peak (March-April 2020), non-peak (May-June 2020), and 2019 control periods. A propensity score-matched comparative analysis was conducted using a logistic regression model, in which period was regressed on observed baseline characteristics. Subsequently, a mixed effects logistic regression model was constructed for each variable of interest. Main variable was FTR. Secondary variables were post-operative complications, readmissions, reinterventions, and length of stay. Results: 5003 patients were included (948, 1108, and 2947 in the pandemic peak, non-peak, and control periods), with comparable clinical characteristics, prognostic scores, complications, reintervention, rehospitalization rates, and length of stay across periods. FTR was greater during the pandemic peak than during non-peak and pre-pandemic periods (22.5% vs. 17.2% and 12.7%), being this difference confirmed in adjusted analysis (odds ratio [OR] 2.13, 95% confidence interval [95% CI] 1.27-3.66). There was sensible inter-hospital variability in FTR changes during the pandemic peak (median FTR change +8.77%, IQR 0-29.17%) not observed during the pandemic non-peak period (median FTR change 0%, IQR -6.01-6.72%). Greater FTR increase was associated with higher COVID-19 incidence (OR 2.31, 95% CI 1.31-4.16) and some hospital characteristics, including tertiary level (OR 3.07, 95% CI 1.27-8.00), medium-volume (OR 2.79, 95% CI 1.14-7.34), and high basal-adjusted complication risk (OR 2.21, 95% CI 1.07-4.72). Conclusion: FTR following emergency surgery experienced a heterogeneous increase during different periods of the COVID-19 pandemic, suggesting it to behave as an indicator of hospital resilience. FTR monitoring could facilitate identification of centres in special needs during ongoing health care challenges

Synthesis of mesoporous silica nanoparticles by sol–gel as nanocontainer for future drug delivery applications

Development of mesoporous silica nanoparticles as carriers for drug delivery systems has increased exponentially during the last decade. The present work is focused on the synthesis of silica carriers by sol–gel from tetraethyl orthosilicate (TEOS) as precursor of silica and cetyltrimethylammonium bromide (CTAB) as pore generating agent. The synthesis conditions were modified varying the molar ratio of water/TEOS, NH3/TEOS and amount of CTAB. The silica particles were characterized by scan electron microscopy techniques (FESEM), high resolution transmission electron microscopy (HR-TEM), N2 adsorption–desorption isotherms, Zeta-potential and Dynamic Light Scattering (DLS). The results show that the specific surface area and the porosity of silica particles were strongly affected by the addition of CTAB and the amount of H2O. The dispersion and stability of silica mesoporous particles is achieved in spite of the high surface reactivity. The synthesis formulation affects considerably to the particle morphology, which changes from spheres to rods when the molar ratio of H2O increases. A maximum specific surface area of 1480 m2/g was obtained with pore sizes ranging 2.5–2.8 nm