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Titanium dioxide nanotubes (TNTs) have been extensively researched for their enhanced biomedical characteristics, including biocompatibility, cell apposition, and growth morphology. However, there is a significant concern in metallic medical devices owing to micro-movements between implants and bone in aggressive environments due to wear and corrosion synergies, leading to adverse body responses and implant failure. In this study, TNTs on Commercially Pure titanium (C.P. Ti) with three different thickness layers were grown to correlate their corrosion and wear behavior. Initially amorphous after anodization, TNTs underwent annealing at 450 °C for 2 h to transform the distorted, into a crystalline structure. The characterization included X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX), X-ray Photoelectron Spectroscopy (XPS), and contact profilometry. Potentiodynamic polarization (PD) and tribocorrosion tests were conducted in Simulated Body Fluid Electrolyte (SBF). SEM micrographs showed TNT thickness layers of 314, 691, and 5280 nm, and X-ray Diffraction showed anatase transformation post-annealing. Results confirmed a significant influence of TNT thickness layers on corrosion and tribocorrosion properties, with higher current density obtained from PD for thicker TNTs layers, associated with surface fluorine content. During tribocorrosion, annealed samples demonstrated lower corrosion tendency, potential drop, and coefficient of friction. Morphology of worn surfaces and volumetric wear rate varied with TNT thickness layer and thermal treatment.

Samples with 40% vol. of pores and a pore size distribution between 100 and 500 µm were produced by powder metallurgy from Ti6Al4V alloy powders. Sintering was performed at 1300 °C during one hour in an inert Argon atmosphere in a vertical dilatometer. The compressive strength and the porosity of these samples was investigated before and after compression tests through X-ray microtomography. The values of the elastic modulus (8GPa) and yield strength (80MPa) are within the range of those used in bone implants. Porosity leads to greater deformation whereas fracture of compacts occurs perpendicularly to the applied load. It was determined that the origin of the failure is generated by rupture of interparticle necks and, large pores enhance the propagation of cracks.

Long-term energy planning increasingly relies on mathematical models offering quantitative insight to support complex policy decisions. However, the increase in their use has meant the proliferation of tools developed at different institutions, with various scopes, dealing with specific aspects of the economy, the power sector, or the climate, with mismatches in temporal or geographic resolution. All this creates a need for using several models concurrently, integrating them to generate a complete perspective on the implications of policy decisions on the energy transition. This article proposes a methodology to categorize and combine energy models and develop a manipulation strategy to answer a target research question. Thus, it gives a formal structure to tasks carried out informally −and suboptimally- in virtually any energy planning project. This methodology is based on structured modeling, a formal mathematical theory conceived for representing and manipulating models. It assumes a soft-linking approach, meaning the models share information without integrating them within the same platform or code. This framework was developed within the European project openENTRANCE, which will develop, use, and disseminate an open, transparent, and integrated modeling platform for assessing low-carbon transition pathways in Europe.

Acute heart failure (HF) is associated with poor prognosis. After the acute event, there is a vulnerable period during which the patient has a marked risk of readmission or death. Therefore, early optimization of treatment is mandatory during the vulnerable period. The objective of this article is to provide recommendations to address the management of patients with HF during the vulnerable period from a practical point of view. A group of Mexican experts met to prepare a consensus document. The vulnerable period, with a duration of up to 6 months after the acute event – either hospitalization, visit to the emergency department or the outpatient clinic/day hospital – represents a real window of opportunity to improve outcomes for these patients. To best individualize the recommendations, the management strategies were divided into three periods (early, intermediate and late vulnerable period), including not only therapeutic options but also evaluation and education. Importantly, the recommendations are addressed to the entire cardiology team, including physicians and nurses, but also other specialists implicated in the management of these patients. In conclusion, this document represents an opportunity to improve the management of this population at high risk, with the aim of reducing the burden of HF.

The European electricity market is becoming increasingly interconnected, raising questions about how intrazonal congestion management, typically governed by national regulations, interacts with the coupled cross-zonal markets. A major concern is the lack of information regarding intrazonal congestion management methods. This paper addresses this issue by examining different ways in which European transmission system operators (TSOs) use third-party resources to manage congestion in short-term electricity markets. We create a decision-tree-based classification to represent all identified congestion management methods and select three cases for comprehensive evaluation using predefined assessment criteria. While doing so, we identify a trade-off between efficiency and ease of implementation. The balance between these two factors is determined by the severity of the congestion. In a severely congested grid, locational signals are critical, requiring a better alignment between the network representation in the market clearing and the physical network constraints. When the congestion is less severe, TSOs can choose other congestion management methods based on factors such as the predictability of congestion and resource availability. These findings shed light on the complexities of congestion management in an integrated European market and can inform future policy decisions.

La insuficiencia cardiaca crónica sigue siendo unas de las principales causas de afectación en el funcionamiento y en la calidad de vida de las personas que la presentan, así como una de las primeras causas de mortalidad en nuestro país y en todo el mundo. México tiene una alta prevalencia de factores de riesgo para desarrollar insuficiencia cardiaca, tales como hipertensión arterial, diabetes y obesidad, lo que hace imprescindible contar con un documento basado en la evidencia que brinde recomendaciones a los profesionales de la salud involucrados en el diagnóstico y el tratamiento de estos pacientes. Este documento establece la guía de práctica clínica (GPC) elaborada por iniciativa de la Sociedad Mexicana de Cardiología (SMC) en colaboración con la Agencia Iberoamericana de Desarrollo y Evaluación de Tecnologías en Salud, con la finalidad de establecer recomendaciones basadas en la mejor evidencia disponible y consensuadas por un grupo interdisciplinario y multicolaborativo de expertos. Cumple con estándares internacionales de calidad, como los descritos por el Institute of Medicine de los Estados Unidos de América (IOM), el National Institute of Clinical Excellence (NICE) del Reino Unido, la Intercollegiate Network for Scottish Guideline Development (SIGN) de Escocia y la Guidelines International Network (G-I-N). El grupo de desarrollo de la guía se integró de manera interdisciplinaria con el apoyo de metodólogos con experiencia en revisiones sistemáticas de la literatura y en el desarrollo de GPC. Se llevó a cabo y se condujo metodología de panel Delphi modificado para lograr un nivel de consenso adecuado en cada una de las recomendaciones contenidas en esta GPC. Esperamos que este documento contribuya para la mejor toma de decisiones clínicas y se convierta en un punto de referencia para los clínicos que manejan pacientes con insuficiencia cardiaca crónica en todas sus etapas clínicas, y de esta manera logremos mejorar la calidad en la atención clínica, aumentar la calidad de vida de los pacientes y disminuir las complicaciones de la enfermedad.

The authors wish to make the following corrections to their article: Magaña Serrano JA, Cigarroa López JA, Chávez Mendoza A, Ivey-Miranda JB, Mendoza Zavala GH, Olmos Domínguez L, Chávez Leal SA, Pombo Bartelt JE, Herrera-Garza EH, Mercado Leal G, Parra Michel R, Aguilera Mora LF, Nuriulu Escobar PL. Corrigendum: Vulnerable period in heart failure: a window of opportunity for the optimization of treatment – a statement by Mexican experts. Drugs Context. 2024;13:2023-8-1. https://doi.org/10.7573/dic.2023-8-1

Intraday markets can be organized as continuous trading or discrete auction sessions. While many studies have attempted to compare the liquidity of these two models, additional external factors specific to each system, such as the balancing market design and number of bidding zones, affect overall market liquidity. In this regard, the Spanish hybrid intraday markets seem like an excellent case study to compare the two market models. Since the two intraday models are implemented in the same system (the Spanish one), the same conditions apply to their implementation. However, a direct comparison of liquidity is still challenging due to two factors: (1) differences exist in market architecture (timing, pricing scheme, bidding formats, etc.) between the two models, which create preferences among market players for one or the other; (2) the opportunistic behavior of market players in the system responding to the market price signals may affect the liquidity dynamics. We demonstrate the relevance of these two factors coming into play in the Spanish intraday markets, first carrying out a qualitative analysis of the market architecture of both models and then empirically analyzing a market manipulation attempt, which we refer to as the 15:10 rush. Our analysis points towards the need for more efficient regulation governing the interaction of the continuous intraday market with intraday auction markets and the potential risks from increased algorithmic trading.

The focus of this work is to analyze the sintering kinetics of Ti12.5Ta12.5Nb alloy by dilatometry. The mixture of powders was achieved by mixing individual powders of Ti, Ta and Nb, which were then axially pressed. Sintering was performed at 1260 °C using different heating rates. The microstructure was determined by X-ray diffraction and scanning electron microscopy. Results show that densification is achieved by solid state diffusion and that the relative density increased as the heating rate was slow. Due to the full solubility of Ta and Nb in Ti, the relative density reached was up to 93% for all samples. Activation energy was estimated from the densification rate and it was determined that two main diffusion mechanisms were predominant: grain boundary and lattice self-diffusion. This suggests that Ta and Nb diffusion did not affect the atomic diffusion to form the necks between particles. The microstructure shows a combination of α, β and α′, and α″ martensitic phases as a result of the diffusion of Ta and Nb into the Ti unit cell. It was concluded that the heating rate plays a major role in the diffusion of Ta and Nb during sintering, which affects the resulting microstructure.

Ti6Al4V (Ti64) alloy is the most used metal material for bone implants because of its good biocompatibility and adapted mechanical properties. Nevertheless, it shows low antibacterial activity, which may favor its failure. Addition of antibacterial elements such as copper should avoid this drawback. This work studies the addition of Cu into a Ti64 matrix resulting in Ti64/xCu composites. Powder mixtures of Ti64/xCu were compacted in a die and then sintered at 1100 °C. Sintering kinetics indicate that densification is achieved by pore filling due to eutectic liquid formed by the reaction of Ti and Cu. The microstructure of the sintered samples is composed mainly of α-Ti and Ti2Cu phases, but TixCuy intermetallics were also found. Microhardness is increased by the addition of Cu due to densification and the formation of harder phases such as Ti2Cu. However, the stiffness and compression strength are barely the same for all composites. The corrosion resistance is significantly improved by the addition of Cu. Finally, the material with 15 wt% of copper showed the best compromise.

A series of Ti–30Zr alloys have been synthesized by the spark plasma sintering (SPS) process using a mixture of elemental powders processed by mechanical alloying. A sintering temperature of 900 °C was used during SPS with heating rates of 140, 200 and 350 °C min−1 with a constant load of 50 MPa. The effect of the heating rate on the densification, microstructure, phase transformation and microhardness is discussed. The sintering kinetics and the in situ densification were performed by the analysis of the punch displacement during SPS processing. Structural details of consolidated materials were evaluated by the combination of X-ray diffraction, field emission scanning electron microscopy and differential scanning calorimetry tests. Vickers microhardness of samples was also evaluated. The results show that samples reached high densification values up to 99.7% of the relative density by using lower sintering temperatures in comparison to conventional sintering techniques. Phase transformation analysis demonstrates the formation of αʹʹ and ω metastable phases without using any post-treatment. Microhardness values between 950 and 1040 HV were obtained as an effect of the SPS parameters and metastable phase precipitations.

Antecedentes: Las enfermedades cardiovasculares son la principal causa mundial de mortalidad y México no es la excepción. Los datos epidemiológicos obtenidos en 1990 mostraron que los padecimientos cardiovasculares representaron el 19.8% de todas las causas de muerte en nuestro país; esta cifra se incrementó de manera significativa a un 25.5% para 2015. Diversas encuestas nacionales sugieren que más del 60% de la población adulta tiene al menos un factor de riesgo para padecer enfermedades cardiovasculares (obesidad o sobrepeso, hipertensión, tabaquismo, diabetes, dislipidemias). Por otro lado, datos de la Organización Panamericana de la Salud han relacionado el proceso de aterosclerosis como la primer causa de muerte prematura, reduciendo la expectativa de vida de manera sensible, lo que tiene una enorme repercusión social. Objetivo: Este documento constituye la guía de práctica clínica (GPC) elaborada por iniciativa de la Sociedad Mexicana de Cardiología en colaboración con la Sociedad Mexicana de Nutrición y Endocrinología, A.C., Asociación Nacional de Cardiólogos de México, A.C., Asociación Mexicana para la Prevención de la Aterosclerosis y sus Complicaciones, A.C., Comité Normativo Nacional de Medicina General, A.C., Colegio Nacional de Medicina Geriátrica, A.C., Colegio de Medicina Interna de México, A.C., Sociedad Mexicana de Angiología y Cirugía Vascular y Endovenosa, A.C., Instituto Mexicano de Investigaciones Nefrológicas, A.C. y la Academia Mexicana de Neurología, A.C.; con el apoyo metodológico de la Agencia Iberoamericana de Desarrollo y Evaluación de Tecnologías en Salud, con la finalidad de establecer recomendaciones basadas en la mejor evidencia disponible y consensuadas por un grupo interdisciplinario de expertos. El objetivo de este documento es el de brindar recomendaciones basadas en evidencia para ayudar a los tomadores de decisión en el diagnóstico y tratamiento de las dislipidemias en nuestro país. Material y métodos: Este documento cumple con estándares internacionales de calidad, como los descritos por el Instituto de Medicina de EE.UU., el Instituto de Excelencia Clínica de Gran Bretaña, la Red Colegiada para el Desarrollo de Guías de Escocia y la Red Internacional de Guías de Práctica Clínica. Se integró un grupo multidisciplinario de expertos clínicos y metodólogos con experiencia en revisiones sistemáticas de la literatura y el desarrollo de guías de práctica clínica. Se consensuó un documento de alcances, se establecieron las preguntas clínicas relevantes, se identificó de manera exhaustiva la mejor evidencia disponible evaluada críticamente en revisiones sistemáticas de la literatura y se desarrollaron las recomendaciones clínicas. Se utilizó la metodología de Panel Delphi modificado para lograr un nivel de consenso adecuado en cada una de las recomendaciones contenidas en esta GPC. Resultados: Se consensuaron 23 preguntas clínicas que dieron origen a sus respectivas recomendaciones clínicas. Conclusiones: Esperamos que este documento contribuya a la mejor toma de decisiones clínicas y se convierta en un punto de referencia para los clínicos y pacientes en el manejo de las dislipidemias y esto contribuya a disminuir la morbilidad y mortalidad derivada de los eventos cardiovasculares ateroscleróticos en nuestro país.

A detailed experimental and numerical investigation was performed on a Ti6Al4V/xCoCrMo biomedical composite for bone implant applications. The aim was to understand the effect generated by the addition of different volume fractions of CoCrMo particles on a Ti6Al4V matrix composite processed by powder metallurgy. Distribution of CoCrMo particles inside a matrix was observed by computed microtomography. Three-dimensional image analysis allowed for the deduction that the mechanism that permitted percolation within the powder mixture was the cluster formation at 30 vol.% of CoCrMo and at a coordination number of Co–Co contacts of 2.8, which confirms existing models. Densification during powder compaction was driven by larger indentations at the Ti–Co contacts for lower quantities of CoCrMo than for those reaching percolation. Sintering was studied by dilatometry tests at 1130 °C, and results indicated that solid-state sintering generated the formation of a rigid skeleton. This endured the stress generated by the eutectic reaction liquid, which filled the interparticle porosity, resulting in relative densities above 90%. Microstructure was analyzed by SEM and X-ray diffraction, and results showed a Ti6Al4V matrix surrounded by a Ti2Co eutectic phase. In addition, the hardness of composites increased up to three times compared to the Ti6Al4V alloy. It was concluded that the best properties were obtained from 20 vol.% of CoCrMo.

A composite of Ti6Al4V reinforced with CoCrMo particles is fabricated by conventional powder metallurgy and semi-solid sintering. Composites are fabricated by mixing 20% wt. of CoCrMo reinforcing particles into the Ti6Al4V matrix. Sintering is studied by dilatometry tests between 1050 and 1130 °C and compact characterization is performed by SEM and XRD. Microhardness is evaluated on the polished surface in order to obtain the mechanical properties. It is found that densification is achieved by the formation of a liquid phase due to a eutectic point formed by the Ti and Co at around 1130 °C. Composites with 93% of relative density are obtained. Their microstructure is composed by the Ti6Al4V matrix surrounded by a Ti2Co phase. Average microhardness of composites is higher than that obtained for monolithic samples of both alloys. It is assessed that the control of the liquid phase is the key to obtain highly dense composites that could be used as dental or orthopedic implants.

A new processing route is proposed to produce graded porous materials by placing particles of Ti6Al4V with different sizes in different configurations to obtain bilayer samples that can be used as bone implants. The sintering behavior is studied by dilatometry and the effect of the layers’ configuration is established. To determine pore features, SEM and computed microtomography were used. Permeability is evaluated by numerical simulations in the 3D real microstructures and the mechanical properties are evaluated by compression tests. The results show that a graded porosity is obtained as a function of the size of the particle used. The mechanical anisotropy due to the pore size distribution and the sintering kinetics, can be changed by the particle layer arrangements. The Young modulus and yield stress depend on the relative density of the samples and can be roughly predicted by a power law, considering the layers’ configuration on the compression behavior. Permeability is intimately related to the median pore size that leads to anisotropy due to the layers’ configuration with smaller and coarser particles. It is concluded that the proposed processing route can produce materials with specific and graded characteristics, with the radial configuration being the most promising for biomedical applications.

Developing a regional power system to achieve a high level of integration of national systems requires sufficient development of the regional transmission grid. This is possible only with appropriate schemes for the complete cost−benefit analyses, and cost allocation of these transmission investments, which plays a critical role in the selection of the most efficient network investment and the proper assignment of their cost to the national systems. Network reinforcements affect the operation of power systems and, therefore, the externalities of power generation. This paper examines the impacts of integrating local air pollution damage from power production within the benefit assessment and cost allocation of transmission investments. The paper describes the methodology followed and illustrates its application in a real-life case study where a simplified version of a European network is considered. Within this case study, we have assessed the impact of considering the reduction in air pollution damage achieved through a particular HVDC project between France and Spain on the benefits, and benefit-driven cost allocation, computed for this project. In this case study, local pollution related benefits are a relevant fraction of the overall benefits of the considered transmission project. However, considering the local air pollution benefits of the project does not affect the net positive benefits of each country significantly, resulting in a limited change in the cost allocation of the project.

La búsqueda de alternativas energéticas de origen renova-ble y la disminución de gases de efecto invernadero pro-venientes de la descomposición de desechos orgánicos hacen del biogás una prometedora alternativa para la sustitución de combustibles fósiles y para la valorización energética de residuos orgánicos en zonas urbanas, rura-les y agroindustriales. En el presente trabajo se realizó un análisis de sensibilidad de las propiedades de combustión del biogás con enriquecimiento de aire con oxígeno en un rango entre 22 y 35% O2. Los resultados indican que la velocidad de deflagración laminar, la temperatura de lla-ma adiabática, el porcentaje en volumen de CO2, la tem-peratura de rocío y el porcentaje de H2O se incrementa-ron cuando el porcentaje de oxígeno en el aire fue mayor que 21% O2, mientras que propiedades como el volumen de aire estequiométrico, volumen de humos húmedos, vo-lumen de humos secos y la energía mínima de ignición, disminuyeron.

La principal desventaja de las aleaciones con memoria de forma ferromagnéticas obtenidas por fundición es su fragilidad. Para superar esta desventaja la metalurgia de polvos es una técnica ideal para la consolidación de las piezas, por lo que este trabajo se orientó a estudiar el efecto generado por los procesos de molienda y sinterizado de polvos sobre la evolución de las fases cristalinas que le confieren la memoria de forma a estos materiales. Para ello se prepararon polvos de la aleación ferromagnética con memoria de forma Ni53.5-Fe19.5-Ga27 a partir de un lingote fundido mediante molienda mecánica, durante dos tiempos diferentes de molienda de 30 y 60 minutos. La evolución de las fases fue estudiada mediante difracción de rayos X (DRX) a alta temperatura (HTXRD), mientras que el sinterizado fue evaluado por medio de ensayos de dilatometría. Los estudios de DRX mostraron que se pueden presentar cuatro fases diferentes en función del tamaño de partícula y de la temperatura de tratamiento térmico. Los polvos de tamaños más gruesos presentaron una estructura B2 acompañados de la fase γ mientras que los más finos presentaban una estructura L21, cuando se trataron por debajo de 1173 K. Por otro lado, los polvos más finos tenían una estructura martensítica modulada M14 después del sinterizado a una temperatura superior a 1273 K. El sinterizado de los polvos fue lento y no indicó claramente un mecanismo de difusión de masa predominante.