Electrochemical behavior of Ti/Al2O3 interfaces produced by diffusion bonding

In the field of biomedical applications a special interest exists regarding the study of the physicochemical and mechanical behaviour of materials, with special focus on the electrochemical degradation of metal/ceramic interfaces. In fact, etal/ceramic interfaces may be present in several biomedical devices, ranging from external or implantable sensors, to dental implants. Diffusion bonding represents an important technique since, in opposition to other production technologies, such as active metal brazing, avoid the possible liberation of certain chemical components harmful to health. The aim of this work is to study the electrochemical degradation of the interface formed between commercially pure Ti and Al2O3 produced by diffusion bonding, in contact with a physiological solution. The present approach included the evaluation of the contribution of individual and pairs of interfacial layers on the global degradation processes. For this propose d.c. electrochemical techniques were used to monitor the open-circuit potential, and to perform potentiodynamic polarization and galvanic corrosion evaluation. Also, electrochemical impedance spectroscopy was used as a complementary technique of the corrosion behaviour of the interface. Chemical composition and morphology of samples and corrosion products were evaluated by SEM and EDS analysis. According to experimental results, two principal reaction layers were formed in the interface: TiAl and Ti3Al. The TiAl layer appears to be the responsible for the strong increase in corrosion rate of the interface.Fundação para a Ciência e Tecnologia -POCTI/CTM/33384/2000; SFRH/BPD/ 5518/2001

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Registro ACESUR: atención de pacientes adultos con crisis epilépticas en servicios de urgencias: diferencias entre primer episodio y recurrencia

Objetivo. Describir las características y la atención recibida de pacientes adultos que consultan por crisis epiléptica (CE) en los servicios de urgencias hospitalarios (SUH), diferenciando entre primera crisis y recurrencia en epiléptico conocido. Método. ACESUR es un registro observacional de cohortes multipropósito, prospectivo y multicéntrico con un muestreo sistemático, los días pares de febrero y julio alternando con los impares de abril y octubre de 2017. Se incluyeron pacientes 18 años con diagnóstico de CE en los SUH. Se recogieron variables clínico-asistenciales de la visita índice de pacientes, distinguiendo entre primera CE y recurrencia en epiléptico. Resultados. El registro ACESUR recogió a 664 pacientes procedentes de 18 SUH españoles, 229 (34, 5%) con primera CE y 435 (65, 5%) con CE recurrentes. Los pacientes con primera CE fueron de mayor edad (p < 0, 001), presentaron motivos de consulta distintos (p < 0, 001) y requirieron más traslados en ambulancia (p < 0, 001). La atención recibida en el SUH fue diferente, en pacientes con primera CE se solicitó con mayor probabilidad una prueba complementaria específica (OR ajustada = 13, 94; IC95%:7, 29-26, 7; p < 0, 001) y se necesitó mayor hospitalización o estancia prolongada en el SUH (OR ajustada = 1, 69; IC95%:1, 11-2, 58; p = 0, 015). No hubo diferencias en cuanto al tratamiento farmacológico en fase aguda ni preventivo (OR ajustada = 1, 40; IC95%:0, 94-2, 09; p = 0, 096). Se inició tratamiento con fármacos antiepiépticos (FAE) en 100 pacientes (43, 7%) tras primera CE y se reinició o modificó añadiendo nuevo FAE en 142 pacientes (32, 6%) con CE recurrentes. Conclusiones. Las características clínicas y la atención recibida de pacientes adultos con primera CE en SUH en España difieren de las recurrencias en epiléptico conocido. Objective. To describe the characteristics of care received by patients who come to the emergency department with a first epileptic seizure versus a recurrent seizure in a patient with diagnosed epilepsy. Methods. ACESUR (Acute Epileptic Seizures in the Emergency Department) is a prospective multicenter, multipurpose registry of cases obtained by systematic sampling on even days in February and July 2017 and on odd days in April and October 2017. Patients were aged 18 years or older and had an emergency department diagnosis of epileptic seizure. We recorded clinical variables and details related to care given during each patient''s visit, including whether the event was a first or recurrent seizure. Results. A total of 664 patients attended by 18 Spanish emergency departments were entered into the ACESUR registry. Two hundred twenty-nine (34.5%) were first seizures and 435 (65.5%) were recurrences. Patients who were attended for first seizures were older, consulted for a wider variety of reasons, and were transported in ambulances (P<.001, all comparisons). Care received differed between patients with first seizures versus recurrent seizures. Specific complementary testing was more likely in patients with first seizures (adjusted odds ratio [aOR], 13.94; 95% CI, 29-26.7; P<.001), and they were more often hospitalized or stayed longer in the emergency department, (aOR, 1.69; 95% CI, 1.11-2.58; P=.015). Pharmacologic treatment did not differ between the groups, either in the acute phase or for prevention (aOR, 1.40; 95% CI, 0.94-2.09; P=.096). Antiepileptic drugs were given to 100 patients (43.7%) after a first seizure and were restarted or changed in 142 patients with recurrent seizure (32.6%). Conclusions. The clinical characteristics of adults attended for a first epileptic seizure differ from those of patients with diagnosed epilepsy who were attended for recurrent seizures in Spain. The care received also differs

Effect of Heat Treatment on the Electrochemical and Mechanical Behavior of the Ti6Al4V Alloy

The effects of heat treatment on the hardness and electrochemical behavior of the Ti6Al4V alloy were studied. Two heat treatments were performed: one below (800 °C) and the other above (1050 °C) its beta transformation temperature (T= 980 ± 20 °C) and cooled using three conditions: water quenching, normalizing, and furnace. A microstructure observed using Optical Microscopy showed dependence on the heat treatment temperature applied; mainly three microstructures were obtained: martensitic, globular, and lamellar. Besides, alpha and beta phases were characterized by X-ray diffraction (XRD) technique. The Berkovich tests were performed to measure the hardness and reduced modulus (E). The Ti6Al4V alloy treated at 1050 °C and air-cooled exhibited hardness values closer to those of the Ti6Al4V as-received alloy. Electrochemical tests were carried out to analyze the electrochemical behavior after 7-day immersion in Hank’s solution at 37 °C and pH 7.40. Open Circuit Potentials (E) showed less negative values for Ti6Al4V and Ti6Al4V alloys, suggesting ennoblement of these materials. Furthermore, these alloys exhibited an outstanding electrochemical behavior compared to the Ti6Al4V as-received alloy by Electrochemical Impedance Spectroscopy (EIS) technique.The authors thank David Pérez-Risco for sharing his experience and useful advice on Berkovich Nano-indenter at the National Metallurgical Research Center (CENIM-CSIC Madrid, Spain), allowing this work to be carried out. Mercedes Paulina Chávez-Díaz thanks the National Science and Technology Council (CONACyT) for a doctoral fellowship to hold a research stay at CENIM-CSIC. This work was supported by the Government of Spain, through the Ministry of Economy and Competitiveness [MAT2015-67750-C3-1]. Elsa Miriam Arce-Estrada and Román Cabrera-Sierra wish to thank the National Research System (SNI) for the distinction of its members and the stipend received

30-day morbidity and mortality of sleeve gastrectomy, Roux-en-Y gastric bypass and one anastomosis gastric bypass: a propensity score-matched analysis of the GENEVA data

Background: There is a paucity of data comparing 30-day morbidity and mortality of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one anastomosis gastric bypass (OAGB). This study aimed to compare the 30-day safety of SG, RYGB, and OAGB in propensity score-matched cohorts. Materials and methods: This analysis utilised data collected from the GENEVA study which was a multicentre observational cohort study of bariatric and metabolic surgery (BMS) in 185 centres across 42 countries between 01/05/2022 and 31/10/2020 during the Coronavirus Disease-2019 (COVID-19) pandemic. 30-day complications were categorised according to the Clavien–Dindo classification. Patients receiving SG, RYGB, or OAGB were propensity-matched according to baseline characteristics and 30-day complications were compared between groups. Results: In total, 6770 patients (SG 3983; OAGB 702; RYGB 2085) were included in this analysis. Prior to matching, RYGB was associated with highest 30-day complication rate (SG 5.8%; OAGB 7.5%; RYGB 8.0% (p = 0.006)). On multivariate regression modelling, Insulin-dependent type 2 diabetes mellitus and hypercholesterolaemia were associated with increased 30-day complications. Being a non-smoker was associated with reduced complication rates. When compared to SG as a reference category, RYGB, but not OAGB, was associated with an increased rate of 30-day complications. A total of 702 pairs of SG and OAGB were propensity score-matched. The complication rate in the SG group was 7.3% (n = 51) as compared to 7.5% (n = 53) in the OAGB group (p = 0.68). Similarly, 2085 pairs of SG and RYGB were propensity score-matched. The complication rate in the SG group was 6.1% (n = 127) as compared to 7.9% (n = 166) in the RYGB group (p = 0.09). And, 702 pairs of OAGB and RYGB were matched. The complication rate in both groups was the same at 7.5 % (n = 53; p = 0.07). Conclusions: This global study found no significant difference in the 30-day morbidity and mortality of SG, RYGB, and OAGB in propensity score-matched cohorts. © 2021, The Author(s)