NRT2.5 a putative sodium dependent high affinity nitrate trasnporter of zostera marina l.

Seagrasses are the only group of vascular plants that recolonized the marine environment, possibly the most severe habitat shift ever accomplished by flowering plants. These plants have regained functions enabling them to thrive in liquid medium with an extremely high salinity (0.5 M Na+), high alkaline conditions (pH 8.2) and very low concentration of essential nutrients as NO3- or Pi. Despite this, seagrasses form one of the highest productive and widespread ecosystems of the planet (Larkum et al., 2006). Zostera marina was the first seagrass fully sequenced and its genome reveals important insights about this secondary adaption. Comparison with land plants indicates that less than 20 % of the genes families are specific in the genome of seagrasses. Thus, adaptation to marine environment seems to be due to molecular changes of the same family genes rather that the speciation of pre-existing genes. This appears to be the case of the high affinity nitrate transporter belonging to the NRT family. In contrast to terrestrial vascular plants, where NRT2 encode high affinity NO3- transporters that operate as H+ symporters, our electrophysiological analysis indicate that in Z. marina high affinity NO3- uptake is mediated by a Na+-dependent mechanism. A detailed analysis of the Z. marina genome indicates the presence of only one gene encoding for this type of transporter: Zosma70g00300.1. Phylogenetic analysis shows that this high affinity nitrate transporter is more related to NRT2.5 than to NTRT2.1, sharing a common ancestor with both, monocot and dicot plants. We have cloned Zosma70g00300.1 and the high-affinity nitrate transporter accessory protein NAR2 (Zosma63g00220.1) in order to characterize the specific transport mechanism mediated by these proteins in Z. marina. Thus, the putative Z. marina NRT2.5 transporter could have evolved to use Na+ as a driving ion, which might be an essential adaptation of seagrasses to colonize the marine environment.MICINN (BFU2017-85117-R; BIO2016-81957-REDT) Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Study of the lateral pass width for conventional and ultrasonic vibrations-assisted ball burnishing on Ti-6Al-4V specimens

Ball burnishing is a technological finishing process based on plastic deformation of the objective surface by means of a hard ball gliding over it. Along with its easiness of application, possible on the same machine where machining was performed [1], burnishing is a comprehensive process able to achieve surface roughness improvements, and compressive residual stresses up to deep layers of the material [2]. Burnishing results have proved to be depending of a proper selection of parameters, which must be correctly controlled during the process. That is the case of burnishing force or the number of passes [3]. Among these parameters, the lateral pass width has proved to be influential on the surface roughness results, due to the behavior that most materials show when being plastically deformed. In effect, the applied force makes the material to flow to the borders of the burnishing imprint, giving way to a pile-up effect. This paper deals with indentation experiments on Ti-6Al-4V to deepen in the burnishing process of this material. Single burnishing imprints are geometrically characterized combining different levels of force, number of passes, and comparing the conventional process with that assisted with vibrations. An optimal lateral pass width is thus determined, and technological recommendations are made for future applications of the process.Peer ReviewedPostprint (author's final draft

Comparison of thermal performance of 3D printer liquefiers through finite element models

Open source 3D printers have experienced an intense expansion during the last years, mainly because of their accessibility and the vast availability of information thanks to user communities. This fact presents researchers with a perfect context for hardware innovation, by improving the overall printing process, also in terms of durability of the printing machine. A 3D printer liquefier must transmit heat to the thermoplastic material in order to extrude it, reaching temperatures above 200 degrees for some materials like ABS on the tip of the nozzle. The design of the heating process must comply with keeping the balance between proper heating of the material and controlling the temperature along the extruding body, so that the printer itself is not harmed for overtemperature. On the other hand, the design must guarantee that the melting front is located in an intermediate point between the nozzle tip and the entrance of the raw material, to minimize pressure drops in the system, and so decreasing the demanding energy to the feeding motors. An alternative design of the heating system, Twist3D, is proposed in this paper.Peer ReviewedPostprint (published version

Experimental analysis of manufacturing parameters’ effect on the flexural properties of wood-PLA composite parts built through FFF

This paper aims to determine the flexural stiffness and strength of a composite made of a polylactic acid reinforced with wood particles, named commercially as Timberfill, manufactured through fused filament fabrication (FFF). The influence of four factors (layer height, nozzle diameter, fill density, and printing velocity) is studied through an L27Taguchi orthogonal array. The response variables used as output results for an analysis of variance are obtained from a set of four-point bending tests. Results show that the layer height is the most influential parameter on flexural strength, followed by nozzle diameter and infill density, whereas the printing velocity has no significant influence. Ultimately, an optimal parameter set that maximizes the material’s flexural strength is found by combining a 0.2-mm layer height, 0.7-mm nozzle diameter, 75% fill density, and 35-mm/s velocity. The highest flexural resistance achieved experimentally is 47.26 MPa. The statistical results are supported with microscopic photographs of fracture sections, and validated by comparing them with previous studies performed on non-reinforced PLA material, proving that the introduction of wood fibers in PLA matrix reduces the resistance of raw PLA by hindering the cohesion between filaments and generating voids inside it. Lastly, five solid Timberfill specimens manufactured by injection molding were also tested to compare their strength with the additive manufactured samples. Results prove that treating the wood-PLA through additive manufacturing results in an improvement of its resistance and elastic properties, being the Young’s module almost 25% lower than the injected material.Preprin

Mechanical properties of 3D-printing polylactic acid parts subjected to bending stress and fatigue testing

This paper aims to analyse the mechanical properties response of polylactic acid (PLA) parts manufactured through fused filament fabrication. The influence of six manufacturing factors (layer height, filament width, fill density, layer orientation, printing velocity, and infill pattern) on the flexural resistance of PLA specimens is studied through an L27 Taguchi experimental array. Different geometries were tested on a four-point bending machine and on a rotating bending machine. From the first experimental phase, an optimal set of parameters deriving in the highest flexural resistance was determined. The results show that layer orientation is the most influential parameter, followed by layer height, filament width, and printing velocity, whereas the fill density and infill pattern show no significant influence. Finally, the fatigue fracture behaviour is evaluated and compared with that of previous studies’ results, in order to present a comprehensive study of the mechanical properties of the material under different kind of solicitations.Peer ReviewedPostprint (published version

Effectiveness of fentanyl buccal tablet for the treatment of breakthrough cancer pain. Review on pharmacokinetics, safety and clinical use in special situations.

Varios estudios han mostrado que la prevalencia del dolor irruptivo en pacientes oncológicos es elevada y que se trata de un problema no completamente resuelto. El tratamiento del dolor irruptivo oncológico (DIO) requiere un fármaco con características específicas siendo probablemente de elección fentanilo, que se presenta en diversas formulaciones. En este trabajo se ha realizado una revisión de los ensayos clínicos publicados sobre el comprimido bucal de fentanilo para valorar la evidencia disponible en relación a su efectividad en el tratamiento del dolor irruptivo oncológico y aspectos relacionados con su farmacocinética, seguridad y particularmente su empleo en condiciones especiales como la mucositis. La evidencia revisada muestra que el comprimido bucal de fentanilo es eficaz en términos de alivio del dolor en el tratamiento de los episodios de DIO, incluyendo los pacientes con mucositis. Se ha revisado también la bioequivalencia entre la administración bucal (entre la encía y la mejilla) y sublingual (bajo la lengua) del preparado.Several studies have shown that the prevalence of breakthrough pain in cancer patients is high and it is a problem not fully solved. Treatment of breakthrough cancer pain requires a drug with specific characteristics and probably the most useful drug is fentanyl, that is available in several formulations. This paper presents a review of published clinical trials on fentanyl buccal tablet to assess the evidence available regarding its effectiveness in the treatment of breakthrough cancer pain, issues related to its pharmacokinetics, safety and its use in special conditions such as mucositis. Evidence shows that fentanyl buccal tablet is effective for relieving pain in the treatment of episodes in breakthrough pain, including patients with mucositis. The bioequivalence of buccal (between the gum and cheek) and sublingual (under the tongue) administration has been also reviewed

El dolor irruptivo oncológico o la cenicienta revelada

Cinderella is a fairy tale character who represents the archetypal young person getting happiness after bitter experiences due to misunderstanding and lack of attention from her family and social environment. Similarly, breakthrough pain is a relevant clinical problem due to its frequency and intensity but it is also a victim of lack of knowledge and lack of interest. Breakthrough pain, despite is a relevant clinical problem because of its high prevalence and its intensity, remains poorly understood and therefore improperly treated and poorly investigated. However, proper diagnosis and assessment are feasible, and treatment includes drugs as fentanyl administered through mucous membranes that fits to the characteristics of the breakthrough pain as the shoe of glass slipper fits in the foot of Cinderella. Other feet have been tested with no luck but only the mysterious kitchen’s girl can legitimize the ownership and therefore be the chosen by the prince.Al igual que la Cenicienta es un personaje de cuento de hadas que representa el arquetipo de persona joven que consigue la plenitud después de amargas pruebas debido a la incomprensión y falta de atención de su entorno familiar y social, el dolor irruptivo oncológico (DIO) es un problema clínico relevante por su frecuencia y su intensidad pero también víctima del desconocimiento y la falta de interés. A pesar de su alta prevalencia e intensidad, sigue siendo un síntoma mal conocido y, por ello, poco investigado e incorrectamente tratado. Sin embargo, son factibles su diagnóstico y evaluación correctos y el tratamiento ha evolucionado al aparecer fármacos basados en el fentanilo administrado a través de las mucosas que se ajustan, como el pie de Cenicienta al zapato de cristal, a las características del dolor irruptivo. Otros pies se habrán probado el zapatito y se habrán mutilado para intentar encajar en él pero sólo la misteriosa habitante de los fogones puede legitimar la propiedad y, por tanto, ser la elegida del príncip

Monitoring of Processing Conditions of an Ultrasonic Vibration-Assisted Ball-Burnishing Process

Although numerous references present the beneficial effects on surface integrity of ultrasonic vibration-assisted ball burnishing (UVABB), nothing has been reported about the dynamic behavior of the UVABB tool, workpiece, and machine triad during the process. In this paper, a dynamic monitorization through a set of 5 accelerometers is tested to analyze the interactions between the tool–workpiece–machine mechanical assembly. A UVABB tool attached to a milling machine and equipped with a piezoelectric stack that is able to assist the process with a 40-kHz vibration is tested on a milled C45 steel surface. First, the natural frequencies of the mechanical system are obtained through hammer impact tests. Then, the vibratory signals transmitted during the execution of the process are monitored and compared to those: two feed velocities and two burnishing preloads, all with and without vibration-assistance. Results show that the proposed accelerometer set is valid to assess the behavior of a UVABB process. The system’s natural frequencies are not varied by vibration-assistance and are not excited when the piezoelectric is functioning. It is confirmed that UVABB is safe for the machine and the tool, and there is no unexpected excited frequencies due to the piezoelectric excitation.Ministerio de Ciencia, Innovación y Universidades de España RTI2018-101653-B-I00Gobierno regional de Cataluña IU68-016744Unión Europea IU68-01674

Effects of inter-resonator coupling in split ring resonator loaded metamaterial transmission lines

This paper investigates the effects of inter-resonator coupling in metamaterial transmission lines loaded with split ring resonators (SRRs). The study is performed from Bloch mode theory applied to the multiport equivalent circuit model of the unit cell of such artificial lines. From this analysis, it follows that the stopband bandwidth, inherent to SRR-loaded lines, is enhanced as inter-resonator coupling strengthens, and this enhancement is attributed to the presence of complex modes. The theoretical results are corroborated through calculation of the dispersion relation using a full-wave eigenmode solver, and also by measuring the frequency response of SRR-loaded lines with different inter-resonator distance and, hence, coupling

Fatigue performance of ABS specimens obtained by fused filament fabrication

In this paper, the fatigue response of fused filament fabrication (FFF) Acrylonitrile butadiene styrene (ABS) parts is studied. Different building parameters (layer height, nozzle diameter, infill density, and printing speed) were chosen to study their influence on the lifespan of cylindrical specimens according to a design of experiments (DOE) using the Taguchi methodology. The same DOE was applied on two different specimen sets using two different infill patterns—rectilinear and honeycomb. The results show that the infill density is the most important parameter for both of the studied patterns. The specimens manufactured with the honeycomb pattern show longer lifespans. The best parameter set associated to that infill was chosen for a second experimental phase, in which the specimens were tested under different maximum bending stresses so as to construct the Wöhler curve associated with this 3D printing configuration. The results of this study are useful to design and manufacture ABS end-use parts that are expected to work under oscillating periodic loads.Peer ReviewedPostprint (published version