Exploring the Interplay between Tribocorrosion and Surface Chemistry of the ASTM F139 Surgical Stainless Steel in Phosphate-Buffered Saline Solution.

Surgical ASTM F139 stainless steel is used for temporary fixtures in the biomedical field. Tribocorrosion is a major concern in this application. The aim of the present work was to study the interplay between tribocorrosion behavior and the surface chemistry of the ASTM F139 stainless steel in phosphate-buffered saline solution (PBS). Sliding wear tests were conducted against alumina balls at different electrochemical potentials: open circuit potential (OCP), cathodic potential (-100 mV versus the OCP), and anodic potentials (+200 mVAg/AgCl and +700 mVAg/AgCl). The normal load was 20 N. The wear volume was estimated based on micrographs obtained from the wear tracks using confocal laser scanning microscopy. Moreover, the wear tracks were also examined by scanning electron microscopy (SEM). The surface chemistry of the ASTM F139 specimens was analyzed by X-ray photoelectron spectroscopy (XPS). The wear volume was dependent on the electrochemical potential, being maximized at +700 mVAg/AgCl. Delamination areas and grooves were observed in the wear tracks. Detailed assessment of the surface chemistry inside the wear tracks allowed identification of the main chemical species and their relative quantities, thus enabling correlation of the passive film composition with the observed tribocorrosion behavior.

Evaluating the catalytic effect of Fe@Fe2O3-modified granulated cork as an innovative heterogeneous catalyst in electro-fenton degradation of benzoquinone in different aqueous matrices.

This study investigated the potential of a novel biomass-derived cork as a suitable catalyst after its modification with Fe@Fe2O3 for in-situ application in heterogeneous electro-Fenton (HEF) process for benzoquinone (BQ) elimination from water. No attempts on the application of modified granulated cork (GC) as a suspended heterogeneous catalyst in the HEF process for water treatment have been published yet. GC was modified by sonification approach in a FeCl3 + NaBH4 solution to reduce the ferric ions to metallic iron in order to obtain Fe@Fe2O3-modified GC (Fe@Fe2O3/GC). Results clearly demonstrated that this catalyst exhibited excellent electrocatalytic properties, such as a high conductivity as well as relatively high redox current and possessed several active sites for water depollution applications. Using Fe@Fe2O3/GC as catalyst in HEF, 100% of BQ removal was achieved in synthetic solutions by applying 33.3 mA cm-2 after 120 min. Different experimental conditions were tested to determine that best possible conditions can be as follow: 50 mmol L-1 Na2SO4 and 10 mg L-1 of Fe@Fe2O3/GC catalyst using Pt/carbon-PTFE air diffusion cell by applying 33.3 mA cm-2. Nevertheless, when Fe@Fe2O3/GC was used in the HEF approach to depollute real water matrices, no complete BQ concentration was removal achieved after 300 min of treatment, achieving between 80 and 95% of effectiveness.

Doped Carbon Quantum Dots/PVA Nanocomposite as a Platform to Sense Nitrite Ions in Meat.

A sensor device based on doped-carbon quantum dots is proposed herein for detection of nitrite in meat products by fluorescence quenching. For the sensing platform, carbon quantum dots doped with boron and functionalized with nitrogen (B,N-Cdot) were synthesized with an excellent 44.3% quantum yield via a one-step hydrothermal route using citric acid, boric acid, and branched polyethylenimine as carbon, boron, and nitrogen sources, respectively. After investigation of their chemical structure and fluorescent properties, the B,N-Cdot at aqueous suspensions showed high selectivity for NO2- in a linear range from 20 to 50 mmol L-1 under optimum conditions at pH 7.4 and a 340 nm excitation. Furthermore, the prepared B,N-Cdots successfully detected NO2- in a real meat sample with recovery of 91.4-104% within the analyzed range. In this manner, a B,N-Cdot/PVA nanocomposite film with blue emission under excitation at 360 nm was prepared, and a first assay detection of NO2- in meat products was tested using a smartphone application. The potential application of the newly developed sensing device containing a highly fluorescent probe should aid in the development of a rapid and inexpensive strategy for NO2- detection.

Gold nanochannels oxidation by confined water.

Confined and interstitial water has a key role in several chemical, physical and biological processes. It is remarkable that many aspects of water behavior in this regime (e.g., chemical reactivity) remain obscure and unaddressed. In particular for gold surfaces, results from simulations indicated that the first wetting layer would present hydrophilic behavior in contrast to the overall hydrophobic character of the bulk water on this surface. In the present work we investigate the properties of confined water on Au 〈111〉 nanochannels. Our findings, based on a large set of morphological, structural and spectroscopic experimental data and ab initio computer simulations, strongly support the hypothesis of hydrophilicity of the first wetting layer of the Au 〈111〉 surface. A unique oxidation process was also observed in the nanochannels driven by confined water. Our findings indicated that the oxidation product is Au(OH)3. Therefore, the Au surface reactivity against confined water needs to be considered for nanoscopic applications such as, e.g., catalysis in fine chemicals, pharmaceuticals, and the food industry green processes.

Pneumoperitônio idiopático em idoso ­ Relato de Caso / Idiopathic Pneumoperitoneum in the Elderly - Case Report

Introdução: O pneumoperitônio frequentemente é causado por perfurações de vísceras ocas, mas, quando não se identifica uma etiologia, é dito idiopático. Relato de caso: Paciente com 80 anos, admitido com quadro de dor abdominal, em pontada, contínua, especialmente em quadrante inferior esquerdo e parada de eliminação de gases e fezes há seis dias. Apresentava-se sudorético, taquicárdico, normotenso, ausculta cardiopulmonar inocente. Passado de colecistectomia e apendicectomia. Exames laboratoriais inalterados. Radiografia e tomografia computadorizada de abdome evidenciaram pneumoperitônio em região subfrênica direita. Paciente foi submetido à laparotomia exploradora e não foram evidenciados sinais de perfuração de víscera oca pós-busca minuciosa da etiologia. Conclusão: Trata-se realmente de causa idiopática, tendo evoluído bem após o procedimento. Entretanto, não há consenso em relação ao melhor tipo de intervenção.

Introduction: Pneumoperitoneum is often caused by perforations of hollow viscera, but when an etiology is not identified, it is said to be idiopathic. Case report: A patient with 80 years of age, admitted with continuous abdominal pain, especially in the lower left quadrant and Stopping gas and stool for six days. She presented sweating, tachycardia, normotensive, and innocent cardiopulmonary auscultation. Past Cholecystectomy and appendectomy. Unchanged laboratory tests. Radiography and computed tomography of the abdomen showed pneumoperitoneum In the right subphrenic region. Patient was submitted to exploratory laparotomy and no signs of hollow viscera perforation were found after search The etiology. Conclusion: This is indeed an idiopathic cause, having evolved well after the procedure. However, there is no consensus Relation to the best type of intervention.

Gangliosidose GM1 infantil ­ relato de caso / Child GM1 Gangliosidosis ­ Case Report

Introdução: A gangliosidose é uma doença caracterizada pelo acúmulo do substrato gangliosídeo nos lisossomos devido à deficiência da enzima betagalactosidase. É uma desordem rara, estimando-se uma incidência na população de 1:100.000 a 200.000. Clinicamente os pacientes apresentam graus variados de neurodegeneração e alterações esqueléticas, categorizadas pela gravidade e atividade residual da beta-galactosidase, podendo ocorrer dismorfismo facial, hepatoesplenomegalia, displasia esquelética, manchas maculares vermelhas, cegueira e até morte precoce. O atraso no desenvolvimento neuropsicomotor associada à degeneração do sistema nervoso central, pode levar o paciente a um quadro de hipotonia muscular generalizada progressiva, evoluindo para espasticidade e crises convulsivas. Objetivo: Relata-se caso de paciente masculino, apresentando alterações no desenvolvimento neuropsicomotor desde os oito meses, com elucidação diagnóstica através da clínica, exames de imagem e laboratoriais. Método: Busca em bancos de dados digitais artigos científicos que discorram sobre a gangliosidose. Resultados/Conclusão: A gangliosiodose é uma disordem rara, o que torna o relato de caso importante como fonte de pesquisa. (AU)

Introduction: Gangliosidosis is a disease characterized by accumulation of the ganglioside substrate in lysosomes due to beta-galactosidase enzyme deficiency. It is a rare disorder, with an incidence of 1: 100,000 to 200,000. Clinically the patients pres- ent varying degrees of neurodegeneration and skeletal changes, categorized by the gravity and residual activity of beta-galactosidase, being able to occur facial dysmorphism, hepatosplenomegaly, skeletal dysplasia, red macular spots, blind- ness and early death. Objective: Delayed neuropsychomotor development associated with degeneration of the central nervous system may lead the patient to progressive generalized muscular hypotonia, evolving into seizures and convulsive seizures. We report a case of male patient, presenting changes in neuropsychomotor devel- opment since eight months of age, with diagnostic elucidation through clinical exam, imaging and laboratory tests. Method: Search in digital databases for scientific articles that discuss gangliosidoses. Results/ conclusion: Gangliosidosis is rare disorder, which makes reporting an important source of research. (AU)

Surface interactions of a W-DLC-coated biomedical AISI 316L stainless steel in physiological solution.

The corrosion stability of a W-DLC coated surgical AISI 316L stainless steel in Hanks' solution has been evaluated. Particle induced X-ray emission (PIXE) measurements were performed to evaluate the incorporation of potentially bioactive elements from the physiological solution. The film structure was analyzed by X-ray diffractometry and micro-Raman spectroscopy. The wear behavior was assessed using the sphere-on-disc geometry. The in vitro biocompatibility of the W-DLC film was evaluated by cytotoxicity tests. The corrosion resistance of the stainless steel substrate decreased in the presence of the PVD layer. EIS measurements suggest that this behavior was closely related to the corrosion attack through the coating pores. PIXE measurements revealed the presence of Ca and P in the W-DLC film after immersion in Hanks' solution. This result shows that the PIXE technique can be applied to identify and evaluate the incorporation of bioactive elements by W-DLC films. The film showed good wear resistance and biocompatibility.

Lessons learned in developing community mental health care in Latin American and Caribbean countries.

This paper summarizes the findings for the Latin American and Caribbean countries of the WPA Task Force on Steps, Obstacles and Mistakes to Avoid in the Implementation of Community Mental Health Care. It presents an overview of the provision of mental health services in the region; describes key experiences in Argentina, Belize, Brazil, Chile, Cuba, Jamaica and Mexico; and discusses the lessons learned in developing community mental health care.

Corrosion fatigue of biomedical metallic alloys: mechanisms and mitigation.

Cyclic stresses are often related to the premature mechanical failure of metallic biomaterials. The complex interaction between fatigue and corrosion in the physiological environment has been subject of many investigations. In this context, microstructure, heat treatments, plastic deformation, surface finishing and coatings have decisive influence on the mechanisms of fatigue crack nucleation and growth. Furthermore, wear is frequently present and contributes to the process. However, despite all the effort at elucidating the mechanisms that govern corrosion fatigue of biomedical alloys, failures continue to occur. This work reviews the literature on corrosion-fatigue-related phenomena of Ti alloys, surgical stainless steels, Co-Cr-Mo and Mg alloys. The aim was to discuss the correlation between structural and surface aspects of these materials and the onset of fatigue in the highly saline environment of the human body. By understanding such correlation, mitigation of corrosion fatigue failure may be achieved in a reliable scientific-based manner. Different mitigation methods are also reviewed and discussed throughout the text. It is intended that the information condensed in this article should be a valuable tool in the development of increasingly successful designs against the corrosion fatigue of metallic implants.

Corrosion processes of physical vapor deposition-coated metallic implants.

Protecting metallic implants from the harsh environment of physiological fluids is essential to guaranteeing successful long-term use in a patient's body. Chemical degradation may lead to the failure of an implant device in two different ways. First, metal ions may cause inflammatory reactions in the tissues surrounding the implant and, in extreme cases, these reactions may inflict acute pain on the patient and lead to loosening of the device. Therefore, increasing wear strength is beneficial to the performance of the metallic implant. Second, localized corrosion processes contribute to the nucleation of fatigue cracks, and corrosion fatigue is the main reason for the mechanical failure of metallic implants. Common biomedical alloys such as stainless steel, cobalt-chrome alloys, and titanium alloys are prone to at least one of these problems. Vapor-deposited hard coatings act directly to improve corrosion, wear, and fatigue resistances of metallic materials. The effectiveness of the corrosion protection is strongly related to the structure of the physical vapor deposition layer. The aim of this paper is to present a comprehensive review of the correlation between the structure of physical vapor deposition layers and the corrosion properties of metallic implants.