Relationship between fibre orientation and tensile strength of natural collagen membranes for heart valve leaflets

Heart valve prostheses are used to replace native heart valves which that are damaged because of congenital diseases or due to ageing. Biological prostheses made of bovine pericardium are similar to native valves and do not require any anticoagulation treatment, but are less durable than mechanical prostheses and usually fail by tearing. Researches are oriented in improving the resistance and durability of biological heart valve prostheses in order to increase their life expectancy. To understand the mechanical behaviour of bovine pericardium and relate it to its microstructure (mainly collagen fibres concentration and orientation) uniaxial tensile tests have been performed on a model material made of collagen fibres. Small Angle Light Scattering (SALS) has been also used to characterize the microstructure without damaging the material. Results with the model material allowed us to obtain the orientation of the fibres, relating the microstructure to mechanical performanc

Efficient Hardware Design Of Iterative Stencil Loops

A large number of algorithms for multidimensional signals processing and scientific computation come in the form of iterative stencil loops (ISLs), whose data dependencies span across multiple iterations. Because of their complex inner structure, automatic hardware acceleration of such algorithms is traditionally considered as a difficult task. In this paper, we introduce an automatic design flow that identifies, in a wide family of bidimensional data processing algorithms, sub-portions that exhibit a kind of parallelism close to that of ISLs; these are mapped onto a space of highly optimized ad-hoc architectures, which is efficiently explored to identify the best implementations with respect to both area and throughput. Experimental results show that the proposed methodology generates circuits whose performance is comparable to that of manually-optimized solutions, and orders of magnitude higher than those generated by commercial HLS tools

CATÁLOGO DE LOS LÍQUENES EPIFÍTICOS DE LA SIERRA DE CORBERA (VALENCIA; ESPANA): COMENTARIOS COROLÓGICOS

In this paper the epiphytic lichen flora of ((Sierra de Corbera)) is studied. 65 species are recognized. Scoliciosporum umbrinum (Ach.) Arnold, Bacidia fuscorrubella (Ach.) Bausch, Bacidia subchlorotica (Nyl.) Flagey, Catillaria melanobola (Nyl.) B. de Lesd., Caloplaca pulchrevirens (Anzi.) Jatta, Caloplaca sarcopisioides (Korber) Zahlbr., Physcia vitii Nádv., Pertusaria leucostoma (Bernh.) Massal., Arthonia fuliginosa (Turn. et Bon.) Flot., Melaspilea bagliettoana Zahlbr., Arthopyrenia platypirenia (Nyl.) Arnold, Polyblastiopsis lactea (IVlassal.) Zahlbr. are new records for the spanish flora. A description of the most important species is given. Ecology and chorology of the most recognized taxa is given. Finally chorologyc conclusions are presented.En el presente trabajo se estudia la flora liquénica epifítica de la Sierra de Corbera. Se citan 65 especies de las que se comenta brevemente su ecología. Se describen de manera concisa las más interesantes de las cuales creemos son taxones nuevos para España: Scoliciosporum umbrinum (Ach.) Arnold, Bacidia fuscorrubella (Ach.) Bausch, Bacidia subchlorotica (Nyl.) Flagey, Catillaria melanobola (Nyl.) B. de Lesd., Caloplaca pulchrevirens (Anzi.) Jatta, Caloplaca sarcopisioides (Korber) Zahlbr., Physcia vitii Nádv., Pertusaria leucostoma (Bernh.) Massal., Arthonia fuliginosa (Turn. et Bon.) Flot., Melaspilea bagliettoana Zahlbr., Arthopyrenia platypirenia (Nyl.) Arnold, Polyblastiopsis lactea (Massal.) Zahlbr. Finalmente se realiza una aproximación corológica de la flora del territorio

Methionine cycle rewiring by targeting miR-873-5p modulates ammonia metabolism to protect the liver from acetaminophen

Drug-induced liver injury (DILI) development is commonly associated with acetaminophen (APAP) overdose, where glutathione scavenging leads to mitochondrial dysfunction and hepatocyte death. DILI is a severe disorder without effective late-stage treatment, since N-acetyl cysteine must be administered 8 h after overdose to be efficient. Ammonia homeostasis is altered during liver diseases and, during DILI, it is accompanied by decreased glycine N-methyltransferase (GNMT) expression and S-adenosylmethionine (AdoMet) levels that suggest a reduced methionine cycle. Anti-miR-873-5p treatment prevents cell death in primary hepatocytes and the appearance of necrotic areas in liver from APAP-administered mice. In our study, we demonstrate a GNMT and methionine cycle activity restoration by the anti-miR-873-5p that reduces mitochondrial dysfunction and oxidative stress. The lack of hyperammoniemia caused by the therapy results in a decreased urea cycle, enhancing the synthesis of polyamines from ornithine and AdoMet and thus impacting the observed recovery of mitochondria and hepatocyte proliferation for regeneration. In summary, anti-miR-873-5p appears to be an effective therapy against APAP-induced liver injury, where the restoration of GNMT and the methionine cycle may prevent mitochondrial dysfunction while activating hepatocyte proliferative response

Screening of substance use and mental health problems among Spanish medical students: A multicenter study

Background: This study aimed to determine the prevalence of substance consumption and mental health problems among Spanish medical students, and their association with sociodemographic factors. Methods: A multicentre cross-sectional study was conducted. Self-reported data on sociodemographic and clinical characteristics were collected, including BDI-II, PHQ-9, brief STAI, and single-item academic burnout (IUBA). Results: Overall, 1265 students (74.2% female) completed the survey. Of them, 37.4% scored positive for depressive symptoms, as measured by the BDI-II, and more than half (53%) by the PHQ-9. Suicidal ideation was reported by about 12% whilst high levels of state and trait anxiety were informed by 28.8% and 29.4% of the students. The prevalence of burnout was 40.2%. Female and pre-clinical students reported significantly (p < 0.01) higher rates of depressive, anxiety, and burnout symptoms. Alcohol, energy drinks, and tobacco were the most frequently used substances. Total scores of self-reported mental health problems negatively correlated (p < 0.001) with objective academic results and positively correlated (p < 0.02) with the number of substances consumed in the last 30 days. Limitations: Research-based on self-reported data could favour information bias due to the social desirability effect and memory error. Conclusions: A high prevalence of substance consumption and several mental health problems was found among medical students, especially females. The relevant influence of academic-related factors on students' well-being may be a call for medical schools to implement initiatives aimed to improve students' ability to detect, address, and seek help for their mental health issues

Efecto de la temperatura en la rotura por despegue de una placa de ateroma

Las placas de ateroma de las paredes arteriales son acumulaciones de lípidos y otras sustancias que modifican las propiedades de la pared vascular. El principal problema que presentan estas placas es su rotura y despegue de la pared, con la posibilidad de obstruir la circulación de la sangre. En este trabajo se analiza, mediante un modelo animal en conejos, el efecto que una variación de temperatura (por ejemplo en un proceso febril) puede tener en la aparición de tensiones tangenciales entre la placa y la pared. Para ello se han obtenido las propiedades termomecánicas de la pared arterial y de la placa de ateroma. Asimismo, se ha elaborado un modelo para estimar las tensiones generadas por un incremento de temperatura. Como ejemplo se muestra que un aumento de la temperatura de 4ºC, que correspondería a una fiebre de algo más de 40ºC, puede generar elevadas tensiones capaces de provocar el despegue de la placa. - Atheroma plaques are accumulations of lipids and other substances attached to the inner side of the artery walls, which modify the mechanical behaviour of the artery wall. Their main problem comes when the plaque breaks and incorporates to the blood flow, because it can eventually block blood circulation and damage to the surrounding tissues and organs. This work explores, by means of a rabbit model, the effect of temperature variation on the development of interfacial shear stresses between plaque and wall. The thermomechanical properties of arterial wall and atheroma plaques have been obtained. A simplified model has also been developed in order to estimate the stress level, which has shown that due to a moderate temperature increment of 4ºC interfacial shear stresses can reach high values, enough to provoke plaque rupture and detachment

Co-pyrolysis of sewage sludge and manure

The management and valorization of residual organic matter, such as sewage sludge and manure, is gaining interest because of the increasing volume of these residues, their localized generation and the related problems. The anaerobic digestion of mixtures of sewage sludge and manure could be performed due to the similarities between both residues. The purpose of this study is to evaluate the feasibility of the co-pyrolysis of sewage sludge (SS) and digested manure (DM) as a potential management technology for these residues. Pyrolysis of a sewage sludge/manure blend (50:50%) was performed at 525 °C in a stirred batch reactor under N2 atmosphere. The product yields and some characteristics of the product were analyzed and compared to the results obtained in the pyrolysis of pure residues. Potential synergetic and antagonist effects during the co-pyrolysis process were evaluated. Although sewage sludge and manure seem similar in nature, there are differences in their pyrolysis product properties and distribution due to their distinct ash and organic matter composition. For the co-pyrolysis of SS and DM, the product yields did not show noticeable synergistic effects with the exception of the yields of organic compounds, being slightly higher than the predicted average, and the H2 yield, being lower than expected. Co-pyrolysis of SS and DM could be a feasible management alternative for these residues in locations where both residues are generated, since the benefits and the drawbacks of the co-pyrolysis are similar to those of the pyrolysis of each residue

Manufacture of Carbon Materials with High Nitrogen Content

Nowadays one of the biggest challenges for carbon materials is their use in CO2 capture and their use as electrocatalysts in the oxygen reduction reaction (ORR). In both cases, it is necessary to dope the carbon with nitrogen species. Conventional methods to prepare nitrogen doped carbons such as melamine carbonization or NH3 treatment generate nitrogen doped carbons with insufficient nitrogen content. In the present research, a series of activated carbons derived from MOFs (ZIF-8, ZIF-67) are presented. Activated carbons have been prepared in a single step, by pyrolysis of the MOF in an inert atmosphere, between 600 and 1000 °C. The carbons have a nitrogen content up to 20 at.% and a surface area up to 1000 m2/g. The presence of this nitrogen as pyridine or pyrrolic groups, and as quaternary nitrogen are responsible for the great adsorption capacity of CO2, especially the first two. The presence of Zn and Co generates very different carbonaceous structures. Zn generates a greater porosity development, which makes the doped carbons ideal for CO2 capture. Co generates more graphitized doped carbons, which make them suitable for their use in electrochemistry.Authors acknowledge financial support by MINECO (Spain) through the project MAT2017-86992-R and “Ministerio de Ciencia e Innovación” (PID2020-116998RB-I00)

Fractional calculus applied to model arterial viscoelasticity

Arterial viscoelasticity can be described using stress-relaxation experiments. To fit these curves, models with springs and dashpots, based on differential equations, were widely studied. However, uniaxial tests in arteries show particular shapes with an initial steep decay and a slow asymptotic relaxation. Recently, fractional order derivatives were used to conceive a new component called spring-pot that interpolates between pure elastic and viscous behaviors. In this work we modified a standard linear solid model replacing a dashpot with a spring-pot of order α. We tested the fractional model in human arterial segments. Results showed an accurate relaxation response during 1-hour with least squares errors below 1%. Fractional orders α were 0.2-0.4, justifying the extra parameter. Moreover, the adapted parameters allowed us to predict frequency responses that were similar to reported Complex Elastic Moduli in arteries. Our results indicate that fractional models should be considered as real alternatives to model arterial viscoelasticity

Strength and stiffness of repaired tendons

Rotator cuff tears of the shoulder are a common cause of pain and disability. Although surgery is frequently beneficial, re-tearing of the tendons is likely to re-occur. In many cases even if the reparation is successful it will still generate discomfort, problems with mobility, as well as a sharp pain. This project is funded in the cooperation with the Hospital Clinico San Carlos de Madrid. The purpose of this work is to analyze the effect of the surgical repair and the application of different therapies, including mesenchymal stem cell therapy on the biomechanical properties (strength and stiffness) of the repaired tendon. An animal model of rotator cuff tendon reparations has been developed on laboratory rats.To obtain the mechanical response of the healthy and repaired tendons, it was necessary to develop an experimental set up to reproduce the in-vivo working conditions of the tendons (37 ºC, immersed in physiological serum), and especially the load transfer. The biomechanical properties (maximum load and stiffness) have been measured in healthy and repaired tendons. A total of 70 rats are used in this particular study. It has been found that the repaired tendon is stronger than the original on. However, the repaired tendons demonstrate less flexibility than the healthy (original) ones prior to the damag