Axial GaAs/Ga(As,Bi) Nanowire Heterostructures

Bi-containing III-V semiconductors constitute an exciting class of metastable compounds with wide-ranging potential optoelectronic and electronic applications. However, the growth of III-V-Bi alloys requires group-III-rich growth conditions, which pose severe challenges for planar growth. In this work, we exploit the naturally-Ga-rich environment present inside the metallic droplet of a self-catalyzed GaAs nanowire to synthesize metastable GaAs/GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ axial nanowire heterostructures with high Bi contents. The axial GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ segments are realized with molecular beam epitaxy by first enriching only the vapor-liquid-solid (VLS) Ga droplets with Bi, followed by exposing the resulting Ga-Bi droplets to As$_2$ at temperatures ranging from 270 to 380\,^{\circ}C to precipitate GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ only under the nanowire droplets. Microstructural and elemental characterization reveals the presence of single crystal zincblende GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ axial nanowire segments with Bi contents up to (10$\pm$2)$\%$. This work illustrates how the unique local growth environment present during the VLS nanowire growth can be exploited to synthesize heterostructures with metastable compounds

Superficial characteristics of titanium after treatment of chorreated surface, passive acid, and decontamination with argon plasma

Background. Titanium is characterized by its biocompatibility, resistance to maximum stress, and fatigue and non-toxicity. The composition, surface structure, and roughness of titanium have a key and direct influence on the osseointegration processes when it is used in the form of dental implants. The objective of the present study is to characterize, at chemical, superficial, and biological levels, the result of the application of the sandblasted with large-grit and acid-etched (SLA) treatment consisting of coarse-grained and double-passivated acid blasting with subsequent decontamination with argon plasma on the surface of titanium implants type IV. (2) Methods. Four Oxtein® dental implants (Zaragoza, Spain) were investigated with the following coding: Code L63713T (titanium grade IV, 3.75 mm in diameter, and 13 mm in length). The surface of the implants was SLA type obtained from coarse-grained, double passivated acid, and decontaminated with argon plasma. The samples were in their sealed packages and were opened in our laboratory. The X-ray photoelectron spectroscopy (XPS) technique was used to characterize the chemical composition of the surface, and the scanning electronic microscope (SEM) technique was used to perform topographic surface evaluation. Cell cultures were also performed on both surfaces. (3) Results. The superficial chemical analysis of the studied samples presented the following components, approximately, expressed in atomic percentage: O: 39%; Ti: 18%; C: 39%; N: 2%; and Si: 1%. In the same way, the topographic analysis values were obtained in the evaluated roughness parameters: Ra: 1.5 μm ± 0.02%; Rq: 1.31 μm ± 0.33; Rz: 8.98 μm ± 0.73; Rp: 5.12 μm ± 0.48; Rv: 3.76 μm ± 0.51; and Rc: 4.92 μm ± 0.24. At a biological level, the expression of osteocalcin was higher (p < 0.05) on the micro-rough surface compared to that machined at 48 and 96 h of culture. (4) Conclusions. The data obtained in our study indicate that the total carbon content, the relative concentration of titanium, and the roughness of the treatment performed on the implants are in agreement with those found in the literature. Further, the roughness of the treatment performed on the implants throws a spongy, three-dimensional surface suitable for bone growth on it. The biological results found are compatible with the clinical use of the surface tested

Superficial characteristics of titanium after treatment of chorreated surface, passive acid, and decontamination with argon plasma

Background. Titanium is characterized by its biocompatibility, resistance to maximum stress, and fatigue and non-toxicity. The composition, surface structure, and roughness of titanium have a key and direct influence on the osseointegration processes when it is used in the form of dental implants. The objective of the present study is to characterize, at chemical, superficial, and biological levels, the result of the application of the sandblasted with large-grit and acid-etched (SLA) treatment consisting of coarse-grained and double-passivated acid blasting with subsequent decontamination with argon plasma on the surface of titanium implants type IV. (2) Methods. Four Oxtein® dental implants (Zaragoza, Spain) were investigated with the following coding: Code L63713T (titanium grade IV, 3.75 mm in diameter, and 13 mm in length). The surface of the implants was SLA type obtained from coarse-grained, double passivated acid, and decontaminated with argon plasma. The samples were in their sealed packages and were opened in our laboratory. The X-ray photoelectron spectroscopy (XPS) technique was used to characterize the chemical composition of the surface, and the scanning electronic microscope (SEM) technique was used to perform topographic surface evaluation. Cell cultures were also performed on both surfaces. (3) Results. The superficial chemical analysis of the studied samples presented the following components, approximately, expressed in atomic percentage: O: 39%; Ti: 18%; C: 39%; N: 2%; and Si: 1%. In the same way, the topographic analysis values were obtained in the evaluated roughness parameters: Ra: 1.5 μm ± 0.02%; Rq: 1.31 μm ± 0.33; Rz: 8.98 μm ± 0.73; Rp: 5.12 μm ± 0.48; Rv: 3.76 μm ± 0.51; and Rc: 4.92 μm ± 0.24. At a biological level, the expression of osteocalcin was higher (p < 0.05) on the micro-rough surface compared to that machined at 48 and 96 h of culture. (4) Conclusions. The data obtained in our study indicate that the total carbon content, the relative concentration of titanium, and the roughness of the treatment performed on the implants are in agreement with those found in the literature. Further, the roughness of the treatment performed on the implants throws a spongy, three-dimensional surface suitable for bone growth on it. The biological results found are compatible with the clinical use of the surface tested

Proyecto de regeneración de una playa en el litoral suratlántico andaluz

La zona de estudio que se aborda en este trabajo se encuadra en el cuadradante Sur-Sureste de la península Ibérica. Playa Peginas pertenece al término municipal de Rota, en la provincia de Cádiz, y se sitúa entre la Barriada de Aguadulce, La Marquesa y La Almadraba, en una zona en expansión urbanística controlada. Abarca un frente litoral de aproximadamente 1.000 metros, situada entre dos polos de difracción formados por sendos salientes rocosos que la separan de la playa de la Ballena y la playa de Punta Candor. (Extraído de los Antecedentes en la Memoria)Universidad de Sevilla. Máster en Ingeniería de Caminos, Canales y Puerto

El desarrollo de competencias digitales en la educación superior

Our research focus on skills acquired by degree students in Universitat Rovira i Virgili. We analyze competences in ICT area to determine if students are “digital natives”. Our literature review concluded ICT use is a critical competence nowadays. We conclude that universities should take part in the development of these skills by developing a holistic learning environment based on technological tools.El presente estudio pretende determinar si las competencias adquiridas por parte de los alumnos de grado de la Universitat Rovira i Virgili convergen con los factores que pudieran definir los nuevos “nativos digitales”. A través de una revisión bibliográfica concluimos que los alumnos cuentan con las habilidades necesarias. Creemos que la universidad debe de tomar parte en el desarrollo de estas competencias, incluyéndolas un entorno holístico en el proceso de aprendizaje

In vitro comparative study of fibroblastic behaviour on polymethacrylate (PMMA) and lithium disilicate polymer surfaces

Polymethyl methacrylate (PMMA) and lithium disilicate are widely used materials in the dental field. PMMA is mainly used for the manufacture of removable prostheses; however, with the incorporation of CAD-CAM technology, new applications have been introduced for this material, including as a provisional implant attachment. Lithium disilicate is considered the gold standard for definitive attachment material. On the other hand, PMMA has begun to be used in clinics as a provisional attachment until the placement of a definitive one occurs. Although there are clinical studies regarding its use, there are few studies on cell reorganization around this type of material. This is why we carried out an in vitro comparative study using discs of both materials in which human gingival fibroblasts (HGFs) were cultured. After processing them, we analyzed various cellular parameters (cell count, cytoskeleton length, core size and coverage area). We analyzed the surface of the discs together with their composition. The results obtained were mostly not statistically significant, which shows that the qualities of PMMA make it a suitable material as an implant attachment

M-learning: aceptación tecnológica de dispositivos móviles en la formación online

Learning is a fundamental tool to develop the Digital Agenda for Europe. Mobile devices are a growing technology with a high penetration in markets, consequently, the future of education must incorporate mobile technologies. The m-learning is a critical dimension to achieve the European 2020 Strategy and improve the competitiveness of European society. Therefore, the purpose of this research is to analyses the acceptance of mobile technologies for learning activities in high education. We identify the key aspects to achieve an adequate strategic and innovative development of m-learning. The main conclusion of the research is that the use of mobile devices is accepted and considered useful by students to carry out their academic activities. We have also found that technological support is not a restriction, since young university students dominate mobile technology and do not require any support to use it as an educational tool. We have also found that technological support is not a restriction, since young university students dominate mobile technology and do not require any support to use it as an educational tool. We demonstrate that user training and technical support are not key aspects for the strategic development of m-learning projects, but whether the adaptation of contents to the mobile environment is crucial.El aprendizaje es una herramienta fundamental en el desarrollo de la Agenda Digital para Europa. Los dispositivos móviles son una tecnología en crecimiento y con unos ratios de uso entre la población cada vez más elevados, lo que hace que el futuro de la educación deba incorporar estos dispositivos. El m-learning es una dimensión crítica para alcanzar la Estrategia Europea 2020 y para mejorar la competitividad de la sociedad europea. El propósito de esta investigación es analizar los retos de la integración de los dispositivos móviles desde la perspectiva de la aceptación tecnológica en las actividades de aprendizaje en la educación superior. Identificamos los aspectos clave para lograr un adecuado desarrollo estratégico e innovador del m-learning. La principal conclusión de la investigación es que el uso de los dispositivos móviles es aceptado y considerado útil por los estudiantes para realizar sus actividades académicas. También hemos encontrado que los conocimientos tecnológicos no representan un freno a su desarrollo, ya que los jóvenes universitarios dominan la tecnología móvil y no necesitan formación alguna para emplearla como herramienta educativa. Demostramos que la formación de usuarios y el soporte técnico no son aspectos clave para el desarrollo estratégico de proyectos de m-learning, pero sí es determinante la adaptación de contenidos al entorno móvil

EFFECTS OF WHOLE-BODY VIBRATION DURING WHEELCHAIR PROPULSION IN INDIVIDUALS WITH COMPLETE SPINAL CORD INJURY

Background: Push the manual wheelchair is one of the most important activities to the wheelchair users like individuals with spinal cord injury (SCI). The excessive or bad use of the upper limb would lead to biomechanical issues and pain. Whole-body vibration applied by vibratory platform (WBV) has been showing great results increasing muscular performance of the upper limb. Although researches regarding the influence of WBV on activity of the upper limb muscles are unclear due to contradictory findings and dissimilar protocols. Objective: The aim of this study was to evaluate the effects of one single session of WBV increasing muscular performance during the propulsion of the wheelchair in SCI. Methods: Fifteen complete SCI were recruited and performed wheelchair propulsion test that consists in to push the manual wheelchair in a 10 meters path as fast as possible. Average speed, push frequency (cadence) and time of displacement were measured before and after WBV intervention. WBV consisted in 5 sets of 30 second vibration with 60 second rest between. The positioning on the platform consisted in supporting the elbows and forearms. Results: Results show a significant increase in average speed and time of displacement. There was no significant difference in push frequency. Conclusion: In conclusion, WBV is an effective tool increasing upper limb performance during propulsion of the wheelchair and it can be useful during the treatment of SCI individuals.   Article visualizations

WBV ON THE UPPER LIMB PERFORMANCE IN COMPLETE SPINAL CORD INJURY

Background: individuals with spinal cord injury (SCI) need upper limbs during activities of daily living that include transferring and propelling a wheelchair. A single session of Whole-body Vibration (WBV) has shown positive impact on musculoskeletal performance. Objective: To investigate the effects of one single session of WBV over the upper limb function in complete SCI during the execution of functional tasks. Design: Individuals with SCI have performed three functional tasks: a timed push up test, grip strength and throw ball test before and after a session of WBV. Participants: 15 individuals with complete SCI were recruited for this study. Interventions: WBV was composed of one single session, five series of thirty seconds vibration with one-minute rest between. The push up test consisted of attempting a maximum number of repetitions during a fifteen second work period followed by a forty-five second rest period. Grip strength was assessed using a handheld dynamometer. Throw ball test consisted on launching a 2Kg medicine ball as afar as possible. Results: WBV statistically improved performance in all three functional tasks. Conclusions: one single session of WBV can improve upper limb performance in complete SCI.   Article visualizations

Comparison of cytomorphometry and early cell response of human gingival fibroblast (HGFs) between zirconium and new zirconia-reinforced lithium silicate ceramics

New zirconia-reinforced lithium silicate ceramics (ZLS) could be a viable alternative to zirconium (Y-TZP) in the manufacture of implantological abutments—especially in aesthetic cases—due to its good mechanical, optical, and biocompatibility properties. Although there are several studies on the ZLS mechanical properties, there are no studies regarding proliferation, spreading, or cytomorphometry. We designed the present study which compares the surface, cellular proliferation, and cellular morphology between Y-TZP (Vita YZ® T [Vita Zahnfabrik (Postfach, Germany)]) and ZLS (Celtra® Duo [Degudent (Hanau-Wolfgang, Germany)]). The surface characterization was performed with energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and optical profilometry. Human gingival fibroblasts (HGFs) were subsequently cultured on both materials and early cellular response and cell morphology were compared through nuclear and cytoskeletal measurement parameters using confocal microscopy. The results showed greater proliferation and spreading on the surface of Y-TZP. This could indicate that Y-TZP continues to be a gold standard in terms of transgingival implant material: Nevertheless, more in vitro and in vivo research is necessary to confirm the results obtained in this study