Optimization of a new Ni-free Ti alloy for applications in the implant field

Three new Ni-free Ti alloys, Ti-16.2Hf-24.8Nb-1Zr, Ti-5.2Hf-31.2Nb-0.4Zr and Ti-16Hf-36.2Nb-1Zr (wt%), were designed and produced in order to obtain shape memory and/or low elastic modulus materials in order to avoid stress shielding and to enhance bone regeneration in the load transfer implant field. The alloys were microstructurally and mechanically characterized, cytotoxicity was evaluated using MG63 osteoblast-like cells. The elastic modulus of the new alloys (between 67-90 GPa) are smaller than those of the commercial alloys employed for implantation. The lowest elastic modulus alloy, Ti-16.2Hf-24.8Nb-1Zr (wt %), with 67.5 GPa, was optimized by cold work in order to determine the key factor that promotes the desired shape memory properties and/or low elastic modulus. A higher proportion of martensite was observed by optical and electron transmission microscopy in the low cold work samples compared to the quenched alloy. The elastic modulus for each cold work condition was evaluated by nanoindentation tests using a spherical tip. The elastic modulus decreases when increasing the cold work level. The lowest value corresponds to the 99% cold work condition, with 44 GPa, closer to that of cortical bone and smaller than the quenched alloy (67.5 GPa).Tres nuevas aleaciones de Ti libres de Ni, Ti-16.2Hf-24.8Nb-1Zr, Ti-5.2Hf-31.2Nb-0.4Zr y Ti-16Hf-36.2Nb-1Zr, porcentajes en peso, fueron diseñadas y fabricadas con el fin de obtener memoria de forma y/o bajo módulo elástico con el objetivo de evitar el apantallamiento de cargas y mejorar la regeneración ósea en el campo de la implantología de transferencia de carga. Las aleaciones fueron caracterizadas microestructural y mecánicamente y la citotoxicidad fue evaluada utilizando osteoblastos MG63. El módulo elástico de las nuevas aleaciones (entre 67-90 GPa) es menor que el de las aleaciones comerciales utilizadas en implantología. El menor módulo elástico corresponde a la aleación Ti-16.2Hf-24.8Nb-1Zr, con 67.5 GPa y fue optimizado mediante trabajo en frío con el objetivo de determinar el factor responsable de la obtención de las propiedades deseadas de bajo módulo elástico y/o memoria de forma. Una mayor proporción de martensita fue observada por microscopía óptica y microscopía electrónica de transmisión en las muestras con bajo porcentaje de trabajo en frío en comparación con la muestra templada. El módulo elástico correspondiente a cada condición de trabajo en frío fue evaluado mediante nanoindentación con punta esférica. El módulo elástico disminuye al aumentar el porcentaje de trabajo en frío. El menor valor corresponde a la condición de 95% de trabajo en frío, con 44 GPa, valor cercano al del hueso cortical y menor que el del material templado (67.5 GPa).Peer Reviewe

Estudio de la biocompatibilidad de una nueva aleación beta-titanio de bajo módulo de elasticidad

Peer Reviewe

Diseño e implementación de tareas de alta demanda cognitiva basadas en la sucesión look and say

Pese a que su tratamiento escolar usual se centra en aspectos principalmente de cálculo, las sucesiones son un tópico matemático con el potencial para desarrollar en los alumnos aspectos del razonamiento matemático. En este trabajo se diseña una secuencia de tareas de alta demanda cognitiva basadas en la sucesión ‘look and say’ y se implementa en un grupo de secundaria con especial interés por las matemáticas durante una sesión del Taller de Talento Matemático en la Universidad de Zaragoza. La metodología es exploratoria y descriptiva con análisis mixto de datos cualitativos. Los alumnos participantes resolvieron las tareas con un alto grado de éxito y surgieron bastantes respuestas de gran riqueza conceptual. Estas tareas pueden ser útiles para trabajar aspectos transversales del currículo e identificar alumnos con altas capacidades matemáticas. Even though their school treatment is mainly based on calculations, numerical sequences are a mathematical topic with the potential to develop aspects of mathematical reasoning amongststudents.In this work, we design a sequence of tasksofcognitive high-demandbased on the ‘look and say’se-quence andimplement them with a group of secondary schoolstudents particularly interested in math-ematics during a session of the Workshop of Mathematical Talent at the University of Zaragoza.The methodology is exploratory and descriptive with mixedanalysis of qualitative data.Participants solved the taskswith a high rate of success and several answers were ofhigh conceptual richness. Thesetasksmight be useful to work transversal curricular aspectsand to identifythosemathematically gifted

Characterization of IHF Binding to DNA Four-Way Junctions and Forks

The objective of the study is to characterise the mechanical properties of Ti-15Zr binary alloy dental implants and to describe their biomechanical behaviour as well as their osseointegration capacity compared with the conventional Ti-6Al-4V (TAV) alloy implants. The mechanical properties of Ti-15Zr binary alloy were characterised using Roxoli

Clinical factors associated with discontinuation of ts/bDMARDs in rheumatic patients from the BIOBADASER III registry

Altres ajuts: Spanish Agency of Medicines and Medical Devices (AEMPS); Biogen; Bristol Myers-Squibb (BMS); Celltrion Healthcare; Lilly; Merck; Novartis; Pfizer; Regeneron Pharmaceuticals; Samsung Bioepis.Biologic and targeted synthetic disease-modifying antirheumatic drugs (ts/bDMARDs) play a pivotal role in the treatment of rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS). Persistence of therapy provides an index of a drug's overall effectiveness. The objective of the study was to identify factors associated with discontinuation of ts/bDMARDs in a real-world dataset. The study population comprised patients diagnosed with RA, PsA, and AS included in the BIOBADASER registry for whom follow-up data were available until November 2019. Patient features and treatment data were included in the analysis. The Kaplan-Meier method was used to study survival of the different drugs according to the reason for discontinuation. Factors associated with discontinuation were studied using Cox regression models and bivariate and multivariate analyses. P values of less than 0.05 were regarded as statistically significant. The study population comprised 4,752 patients who received a total of 8,377 drugs, of which 4,411 (52.65%) were discontinued. The Kaplan-Meier curves showed that survival for first-line treatment was greater in all 3 groups (p < 0.001). Patients with RA had a greater risk of discontinuation if they were younger (HR, 0.99; 95% CI 0.99-1.00), if they were receiving anti-TNFα agents (HR, 0.61; 95% CI 0.54-0.70), and if they had more comorbid conditions (HR, 1.09; 95% CI 1.00-1.17). Patients with PsA had a higher risk if they were women (HR, 1.36; 95% CI 1.15-1.62) and if they were receiving other ts/bDMARDs (HR, 1.29; 95% CI 1.05-1.59). In patients with AS, risk increased with age (HR, 1.01; 95% CI 1.00-1.02), as did the number of comorbid conditions (HR, 1.27; 95% CI 1.12-1.45). The factors that most affected discontinuation of ts/bDMARDs were line of treatment, age, type of drug, sex, comorbidity and the year of initiation of treatment. The association with these factors differed with each disease, except for first-line treatment, which was associated with a lower risk of discontinuation in all 3 diseases

Role of targeted therapies in rheumatic patients on COVID-19 outcomes: Results from the COVIDSER study

Objectives To analyse the effect of targeted therapies, either biological (b) disease-modifying antirheumatic drugs (DMARDs), targeted synthetic (ts) DMARDs and other factors (demographics, comorbidities or COVID-19 symptoms) on the risk of COVID-19 related hospitalisation in patients with inflammatory rheumatic diseases. Methods The COVIDSER study is an observational cohort including 7782 patients with inflammatory rheumatic diseases. Multivariable logistic regression was used to estimate ORs and 95% CIs of hospitalisation. Antirheumatic medication taken immediately prior to infection, demographic characteristics, rheumatic disease diagnosis, comorbidities and COVID-19 symptoms were analysed. Results A total of 426 cases of symptomatic COVID-19 from 1 March 2020 to 13 April 2021 were included in the analyses: 106 (24.9%) were hospitalised and 19 (4.4%) died. In multivariate-adjusted models, bDMARDs and tsDMARDs in combination were not associated with hospitalisation compared with conventional synthetic DMARDs (OR 0.55, 95% CI 0.24 to 1.25 of b/tsDMARDs, p=0.15). Tumour necrosis factor inhibitors (TNF-i) were associated with a reduced likelihood of hospitalisation (OR 0.32, 95% CI 0.12 to 0.82, p=0.018), whereas rituximab showed a tendency to an increased risk of hospitalisation (OR 4.85, 95% CI 0.86 to 27.2). Glucocorticoid use was not associated with hospitalisation (OR 1.69, 95% CI 0.81 to 3.55). A mix of sociodemographic factors, comorbidities and COVID-19 symptoms contribute to patients'' hospitalisation. Conclusions The use of targeted therapies as a group is not associated with COVID-19 severity, except for rituximab, which shows a trend towards an increased risk of hospitalisation, while TNF-i was associated with decreased odds of hospitalisation in patients with rheumatic disease. Other factors like age, male gender, comorbidities and COVID-19 symptoms do play a role.

Friction coefficients and wear rates of different orthodontic archwires in artificial saliva

The aim of this paper is to analyze the influence of the nature of the orthodontic archwires on the friction coefficient and wear rate against materials used commonly as brackets (Ti–6Al–4V and 316L Stainless Steel). The mate- rials selected as orthodontic archwires were ASI304 stainless steel, NiTi, Ti, TiMo and NiTiCu. The array archwire’s materials selected presented very similar roughness but different hardness. Materials were chosen from lower and higher hardness degrees than that of the brackets. Wear tests were carried out at in artificial saliva at 37 C. Results show a linear relationship between the hardness of the materials and the friction coefficients. The material that showed lower wear rate was the ASI304 stainless steel. To prevent wear, the wire and the brackets have high hardness values and in the same order of magnitude.Peer ReviewedPostprint (published version

Experimental Observation of Differences in the Dynamic Response of Newtonian and Viscoelastic Fluids

In this paper we present an experimental study of the dynamic responses of a Newtonian fluid and a Maxwellian fluid under an oscillating pressure gradient. We use laser Doppler anemometry in order to determine the velocity of each fluid inside a cylindrical tube. In the case of the Newtonian fluid, the dissipative nature is observed and the response obeys the Zhou and Sheng universality (PRB 39, 12027 (1989)). In the dynamic response of the Maxwellian fluid an enhancement at the frequencies predicted by the corresponding theory (PRE 58, 6323 (1998)) is observed.Comment: 5 pages, 4 Figures, paper to be published in Phys. Rev.

CLUH couples mitochondrial distribution to the energetic and metabolic status

Mitochondrial dynamics and distribution are critical for supplying ATP in response to energy demand. CLUH is a protein involved in mitochondrial distribution whose dysfunction leads to mitochondrial clustering, the metabolic consequences of which remain unknown. To gain insight into the role of CLUH on mitochondrial energy production and cellular metabolism, we have generated CLUH-knockout cells using CRISPR/Cas9. Mitochondrial clustering was associated with a smaller cell size and with decreased abundance of respiratory complexes, resulting in oxidative phosphorylation (OXPHOS) defects. This energetic impairment was found to be due to the alteration of mitochondrial translation and to a metabolic shift towards glucose dependency. Metabolomic profiling by mass spectroscopy revealed an increase in the concentration of some amino acids, indicating a dysfunctional Krebs cycle, and increased palmitoylcarnitine concentration, indicating an alteration of fatty acid oxidation, and a dramatic decrease in the concentrations of phosphatidylcholine and sphingomyeline, consistent with the decreased cell size. Taken together, our study establishes a clear function for CLUH in coupling mitochondrial distribution to the control of cell energetic and metabolic status

The comparative responsiveness of Hospital Universitario Princesa Index and other composite indices for assessing rheumatoid arthritis activity

Objective To evaluate the responsiveness in terms of correlation of the Hospital Universitario La Princesa Index (HUPI) comparatively to the traditional composite indices used to assess disease activity in rheumatoid arthritis (RA), and to compare the performance of HUPI-based response criteria with that of the EULAR response criteria. Methods Secondary data analysis from the following studies: ACT-RAY (clinical trial), PROAR (early RA cohort) and EMECAR (pre-biologic era long term RA cohort). Responsiveness was evaluated by: 1) comparing change from baseline (Delta) of HUPI with Delta in other scores by calculating correlation coefficients; 2) calculating standardised effect sizes. The accuracy of response by HUPI and by EULAR criteria was analyzed using linear regressions in which the dependent variable was change in global assessment by physician (Delta GDA-Phy). Results Delta HUPI correlation with change in all other indices ranged from 0.387 to 0.791); HUPI's standardized effect size was larger than those from the other indices in each database used. In ACT-RAY, depending on visit, between 65 and 80% of patients were equally classified by HUPI and EULAR response criteria. However, HUPI criteria were slightly more stringent, with higher percentage of patients classified as non-responder, especially at early visits. HUPI response criteria showed a slightly higher accuracy than EULAR response criteria when using Delta GDA-Phy as gold standard. Conclusion HUPI shows good responsiveness in terms of correlation in each studied scenario (clinical trial, early RA cohort, and established RA cohort). Response criteria by HUPI seem more stringent than EULAR''s