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ObjectivesGI endoscopy units represent the third largest producers of medical waste. We aimed to determine endoscopic instrument composition and life cycle assessment (LCA) and to assess a sustainability proposal based on a mark on the instruments that identifies parts can be safely recycled or ‘green mark’.DesignMaterial composition analysis and LCA of forceps, snares and clips from four different manufacturers (A–D) were performed with four different methods. Carbon footprint from production, transportation and end of life of these instruments was calculated. In 30 consecutive procedures, we marked the contact point with the working channel. 5 cm away from that point was considered asgreen mark. One-week prospective study was conducted with 184 procedures evaluating 143 instruments (75 forceps, 49 snares and 19 haemoclips) to assess the efficacy of this recyclable mark.ResultsComposition from different manufacturers varied widely. Most common materials were high global warming potential (GWP) waste (polyethylene, polypropylene and acrylonitrile) and low GWP waste (stainless steel). Significant differences were found for the forceps (0.31–0.47 kg of CO2equivalent (CO2-eq)) and haemoclips (0.41–0.57 kg CO2-eq) between the manufacturers.Green markwas established 131.26 cm for gastroscope and 195.32 cm for colonoscope. One-week activity produced 67.74 kg CO2-eq. Applying our sustainability intervention, we could reduce up to 27.44% (18.26 kg CO2-eq). This allows the recycling of 61.7% of the instrument total weight (4.69 kg).ConclusionKnowledge of carbon footprint is crucial to select the most sustainable alternatives because there are large variations between brands. A mark to identify recyclable parts could reduce our environmental impact significantly.

[EN] Polycaprolactone/Graphene oxide (PCL/GO) composites are shown to be promising substrates for tissue engineering as their degradation behavior is a key aspect in this type of application. The present paper studies the effect of different GO contents (0.1, 0.2 and 0.5 wt%) of PCL/GO composites on accelerated hydrolytic degradation at pH 13 and pH 1. Degradation kinetics at pH 13 is strongly affected by GO content, and speed up at higher percentages. The composite with 0.5 wt% of GO was completely degraded in 72 hours, while degradation at pH 1 presents a different profile and seems to have an induction period that lasts more than 1500 hours. Morphological changes, molecular weight distribution, weight loss, degree of swelling and calorimetric properties were obtained as a function of degradation time. According to the results obtained, the addition of small percentages of GO significantly influences the degradation behavior of the composites acting as degradation modulators., Isabel Castilla-Cortazar and Alberto J. Campillo-Fernandez are grateful for the support of the Spanish Ministry of Science, Innovation and Universities, through RTI2018-095872-B-C22/ERDE Ana Vidaurre would like to express her gratitude for the support of the Spanish Ministry of Science and Education, through the MAT2016-76039-C4-1-R Project, and also the support from CIBER-BBN, an initiative funded by the Sixth National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CII3ER Actions financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.

[EN] The lockdown period that started on March 2020 due to the COVID-19 pandemic was a big challenge for students and teachers. Technology made the continuation of the teaching easier, and it also allowed teachers to keep the contact both with colleagues and with students. New teaching and evaluation methodologies and new coordination and cooperation systems had to be quickly implemented. Our previous experience in flipped teaching, active methodologies and validation of online exams, helped us to tackle the transition from face-to-face to fully online teaching. The experience was satisfactory for the theory classes, but some problems in the laboratory classes have emerged. After that, right now, some extra work is needed to overcome these difficulties considering that maybe the situation would become chronic. Once that we got over the shock of the first moment, the question is whether the resilience mechanisms will remain, and if the hybrid teaching (face-to-face & online) can replace effectively face-to-face teaching for a long time. In this work we present the students¿ opinion on this question. The analysis has been performed at the School of Design Engineering of the Universitat Politècnica de València, in different courses of physics of several engineering degrees (all of them, first academic year courses). One example of good practice during confinement was the weekly coordination meetings between teachers of the same course and between teachers of physics courses in different degrees. Another one was the online exams, taking advantage of the automatic correction tests, and including images of the documents written by the students for later review. The academic results were comparable to those of a normal course and student and teachers' surveys were conducted to know their opinion. The good performance during this new situation was due to the collaboration, patience, understanding and trust of the students and teachers that was created in those moments of crisis. Students' opinion on the online teaching during their lockdown was positive. This work shows this students' opinion on the methodology used during the lockdown, and the process from previous flipped teaching methodologies experiences to a completely online teaching. At the same time, the students' opinion on the laboratory practices was also analysed. Finally, this work also shows the reflection of the involved teachers on the additional workload and on the capacity for cooperation and communication between them, during the lockdown period and the subsequent year. After gathering the opinion of teachers and students, we can conclude that the situation of the pandemic has been addressed with reasonable success. Performance of students is not affected, the theoretical classes have been developed normally, while the practical classes seem to need some changes to be adapted to the new situation as far as possible. Given that this situation persists, it is useful to carry out this type of study to be able to adapt teaching to future circumstances., Authors would like to thank the Institute of Education Sciences of the Universitat Politècnica de València (Spain) for supporting the Teaching Innovation Group e-MACAFI and for the financial support through PIME Project PIME/2018/B25 and PIME Project PIME/2018/B26

[EN] Nowadays, it is well stablished the effectiveness of flip teaching in different areas. Video is widely used as a pre-class learning material and it is progressively replacing text-document materials. The students, 70 in total, are enrolled in the laboratory practice of the subject of Physics (Bachelor¿s Degree: Industrial Electronics and Automation Engineering) at the Universitat Politècnica de València. Student¿s perception data were collected from the results of a survey. Students were asked about the usefulness of the videos and the in-class work, paying special attention to the roll of the instructor in relation to the flip teaching methodology and the pre-class material. The students were divided into two groups. In one of them, the videos were recorded by the same instructor present at the lab session, whereas the other group, the videos used were recorded by instructors different from the instructor present at the lab. The results indicate that students feel that the videos are very useful, rather than the written documents. They attribute a high value to the instructor in the lab session as they feel more confident with their work and they can ask for help when needed. They value positively the possibility of work autonomously. Small differences have been found in the opinion of both groups being the higher in the question that concerns the preference of the videos respect to the text., This work has been supported by the Universitat Politècnica de València through the Project of Innovation and Educational Improvement Program (Projects PIME/2018/B26 and PIME/2018/B25 Convocatoria de Proyectos de Innovación y Convergencia).

[EN] This paper shows the data of the Flip Teaching and Traditional Methodology on the laboratory practice in two subjects, Physics and Electricity, of a technical degree. The laboratory and final grades of these subjects were shown in four consecutive years. The characteristics of all four years were quite similar, except that the Traditional teaching Methodology (TM) was used in two, while Flip Teaching methodology (FT) was applied in the other two. For further discussion, please refer to the scientific article entitled "Effectiveness of flip teaching on engineering students' performance in the physics lab" [1]. Additional segmentation data in three levels are presented in this data in brief paper., This work was supported by the Universitat Politecnica de Valencia [Project PIME/2018/B25 Convocatoria de Proyectos de Innovacion y Convergencia de la UPV].

[EN] In recent years, new teaching methodologies have entered in the high education scenario: blended learning, problem-based learning, learning-oriented assessment, flip teaching, teamwork and effective oral and written communication are new pedagogical tools used in new instruction strategies. A key issue to guide the application of these new methodologies is the assessment of students performance. One broadly used tool for measure the student¿s performance in introductory physics is the Brief Electricity and Magnetism Assessment (BEMA), designed specifically as a standardized instrument to evaluate students¿ qualitative understanding of electricity and magnetism (E&M) key concepts. The reliability and discriminatory capability of BEMA has been previously studied. In this paper, BEMA is used to analyse the performance of E&M students. The E&M course analyzed is included in two different Bachelor¿s Degrees: Industrial Electronics and Automation Engineering (DIEA) and Aerospace Engineering (DA) both in Universitat Politècnica de València (UPV), Spain. They are semester traditional curriculums in which the use of traditional textbooks and screencast have been combined, including flip teaching methodologies. BEMA pre- and post-instruction tests were carried out at the beginning and end of the course respectively. To deepen understanding of student learning in the E&M course, correlations of pre- and post-instruction scores have been investigated, identifying the main gain and variance. The relevant information obtained through the BEMA test will allow instructors to monitor the use of new methodologies and teaching tools., This work has been supported by the Universitat Politècnica de València through the Project of Innovation and Educational Improvement Program (Projects PIME/2018/B26 and PIME/2018/B25 Convocatoria de Proyectos de Innovación y Convergencia).

[EN] This paper presents a qualitative study on the evaluation work performed by students of two courses, Physics and Electricity, included in the first year of Electronic and Automatic Engineering Degree (School of Design Engineering) at the Universitat Politècnica de València. The teaching methodologies used include continuous and formative assessment. The activity analyzed, based on peer assessment, consists of a problem to be solved by students. The solution is reflected in a document to be evaluated by other students and instructors. In order to guide students in the evaluation process, a rubric was provided, which includes aspects to consider related to the assessment to be performed. In addition, effective communication transversal competence was assessed. Both tasks, problem resolution and evaluation, were performed in teams. Each team was made up of six members. The teams were the same in the two courses since they are consecutive, taught in first and second semester (one academic year). Each team had to solve six problems and evaluate six resolutions (from other teams) throughout both courses, without repeating the evaluated team (144 evaluations were analysed). The study has been developed in three parts; in the first one, it is analysed how the evaluation work of the teams evolved throughout the academic year. In the second part, the evaluations carried out by two different teams on the same problem resolution were compared, and finally, in the last part, the assessment made by students was compared with the one made by experienced instructors, both using the same rubric for the assessment. The results of the study show that students carry out thoughtful and rigorous assessment work. It was also found that evaluations of the same work carried out by different teams resulted in very close ratings, which supported the credibility of the evaluations. Therefore, we can conclude that methodologies based on peer assessment encourage the active participation of students and enhance their learning., This work has been supported by the Universitat Politècnica de València through the Project of Innovation and Educational Improvement Program (Projects PIME/2018/B26 and PIME/2018/B25 Convocatoria de Proyectos de Innovación y Convergencia).

The authors acknowledge the support of the Ministerio de Economia y Competitividad, MINECO, through the MAT2016-76039-C4-1-R project. Maria Amparo Gamiz Gonzalez acknowledges a BES-2011-044740 grant. CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions, and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. The authors acknowledge the assistance and advice of the Electron Microscopy Service of the UPV.

[EN] The use of the PoliformaT tool has been analysed, both in terms of the number of visits and their temporary distribution. As an example, the temporary pattern of visits to some videos has also been analysed. Both patterns have been analysed according to the date of the examination on the topic. In addition, an opinion survey has been carried out in which the students have been asked about the methodology and the tools and means available. The results indicate that the students work regularly with a good organization of time. They visit the page continuously with a slight increase the days before the exam, while they visit the videos earlier, more linked to the presentation of the corresponding topic., [ES] Se ha analizado el uso de la herramienta de PoliformaT, tanto el número de visitas como su distribución temporal. También se ha analizado, a modo de ejemplo, el patrón temporal de visitas a algunos vídeos. Ambos patrones se han analizado en función de la fecha del examen sobre esa materia. Además se ha realizado una encuesta de opinión en la que los estudiantes han valorado la metodología y las herramientas y medios disponibles. Los resultados indican que los alumnos trabajan de forma regular con una buena organización del tiempo. Visitan la página de forma continua con un ligero incremento los días antes del examen, mientras que visitan los vídeos con mayor antelación, más ligado a la presentación del tema correspondiente., Los autores agradecen al Instituto de Ciencias de la Educación de la Universitat Politècnica de València su apoyo al grupo de Innovación e-MACAFI y al Proyecto PIME/2018/B25.

[EN] For this work, we report on the results of the BEMA assessment for students of Electricity courses of Engineering Degrees taught at the Higher Technical School of Design Engineering (ETSED) Universitat Politécnica de Valéncia (UPV). The BEMA pre-test and post-test assessment was delivered at the beginning and at the end of the course to students of the Degrees on Electronic Engineering and Industrial Automation (DEEIA) and Aerospace Engineering (DAE). The gain in the performance of BEMA test was analysed for both curricula and for three categories: electrostatics, dc current circuits and magnetostatics. The results show better results for DAE curriculum in the pre-test, but a lower gain in the post-test. The highest gain is obtained in magnetostatics, and no influence of the use of screencast is appreciated., Financial support through PIME Projects PIME/2018/A25 and PIME/2018/A26.

The present paper studies the effect of pH on hydrolytic degradation of Poly(ε-aprolactone) (PCL) Degradation of the films was performed at 37 C in 2.5 M NaOH solution (pH 13) and 2.5 M HCl solution (pH 1). Weight loss, degree of swelling, molecular weight, and calorimetric and mechanical properties were obtained as a function of degradation time. Morphological changes in the samples were carefully studied through electron microscopy. At the start of the process the degradation rate of PCL films at pH 13 was faster than at pH 1. In the latter case, there was an induction period of around 300 h with no changes in weight loss or swelling rate, but there were drastic changes in molecular weight and crystallinity. The changes in some properties throughout the degradation period, such as crystallinity, molecular weight and Young s modulus were lower in degradations at higher pH, highlighting differences in the degradation mechanism of alkaline and acid hydrolysis. Along with visual inspection of the degraded samples, this suggests a surface degradation at pH 13, whereas bulk degradation may occur at pH 1., The authors would like to acknowledge the support of the Spanish Ministry of Science and Education through the MAT2013-46467-C4-1-R Project. A. Vidaurre would also like to acknowledge the support from CIBER-BBN, an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.

Water absorption in chitosan rapidly increases when the deacetylation degree decreases between 85 and 45%. This seems to contradict the fact that water absorption in chitin is much lower than that of chitosan. The aim of this paper is to understand this feature by measuring the main parameters affecting equilibrium water content. Since swelling capacity depends on the water–polymer interaction, the Flory Huggins interaction parameter was evaluated, finding small or null dependence on the deacetylation degree. Other factor influencing elastic energy is chain stiffness related to the elastic modulus that was measured as a function of deacetylation degree. Besides, crystalline structure was measured by X-ray diffraction patterns as a characteristic of cross-linking density. These observations led us to conclude that the instability of crystals during the swelling process increases with decreasing deacetylation degree, explaining the high equilibrium water content of low deacetylation chitosans., The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the MAT2013-46467-C4-1-R project, including FEDER funds. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with the assistance of the European Regional Development Fund.

[EN] Using enteroscopes with therapeutic capacity to explore the small intestine entails certain limitations, including long exploration times, patient discomfort, the need for sedation, a high percentage of incomplete explorations and a long learning curve. This article describes the advances and setbacks encountered in designing the new Endoworm enteroscopy system, a semi-autonomous device consisting of a control unit and three cavities that inflate and deflate in such a way that the bowel retracts over the endoscope. The system can be adapted to any commercial enteroscope. Endoworm was tested in different intestine models: a polymethyl methacrylate rigid tube, an in vitro polyester urethane model, an ex vivo pig model and an in vivo animal model. The general behavior of the prototype was evaluated by experienced medical personnel. The mean distance covered through the lumen was measured in each cycle. The system was found to have excellent performance in the rigid tube and in the in vitro model. The ex vivo tests showed that the behavior depended largely on the mechanical properties of the lumen, while the in vivo experiments suggest that the device will require further modifications to improve its performance., The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through Project PI12/01000 and also from UPV/IIS LA Fe through the Endoworm 3.0 Project. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008–2011, Iniciativa Ingenio 2010, Consolider Program and CIBER Actions, and financed by the Instituto de Salud Carlos III with the assistance of the European Regional Development Fund.

Poly(L-lactic acid)(PLLA)/poly(e-caprolactone)(PCL)/hydroxyapatite(HAp) composites appear as promising materials for healing large bone defects. Highly porous PLLA/PCL scaffolds, 80/20, 20/80 weight ratios, porosity >85%, were prepared by a dual technique of freeze extraction and porogen leaching, with and without HAp. A double pore structure was obtained, with interconnected macroporosity together with interconnected microporosity. Subsequent long-term (78 weeks = 1.5 years) hydrolytic degradation behavior was investigated in terms of the samples' mechanical properties, molecular weight (M w ), mass changes, thermal characteristics, X-ray Diffraction and Thermogravimetric Analysis. Elastic modulus and yield strength of as-synthesized scaffolds were higher for PLLA rich blends and including the inorganic phase does not lead to a mechanical strengthening in these materials. Nevertheless, after 30 weeks of degradation, PLLA rich scaffolds lost more than half of their strength and rigidity. On the contrary, the densification modulus of the PLLA based blends increased with degradation time, whereas PCL-based blends had a relatively constant densification modulus. PCL-based samples showed lower hydrolysis coefficients k than PLLA-based samples, as expected from the higher density of ester bonds in the latter. Interestingly, although including HAp leads to a lower hydrolysis coefficient k in PCL rich samples, it increases k in the PLLA-based sample, which is consistent with the other results obtained.

[EN] In this paper, the use of online exams as part of the evaluation process in the context of blended assessment has been studied. The online exams have been used in three different situations: in an evaluation-proctored exam, in an evaluation-unproctored exam and as a training-homework task. The analysis shows that the students' online mark clearly depends on the way the online exam was performed. It has also been proved that the weight of the online exams in the final mark does not affect the results of the online exams, and that the results obtained in the unproctored environment present a bias towards higher ratings, as well as a greater dispersion of results regarding the case of proctored environment., This work has been supported by the Universitat Politecnica de Valencia through the A26/12 project (Convocatoria de Proyectos de Innovacion y Convergencia de la UPV). We would like to thank the ICE in the Universitat Politecnica de Valencia for their help through the innovation and educational quality program and for supporting the team Innovacion en Metodologias Activas para el Aprendizaje de la Fisica (e-MACAFI).

[EN] The students’opinion about the videos used in the flipped teaching in laboratory sessions is analized in this work. A survey with 7 multiple choice questions and one open question has been performed, obtanining 54 replies, from a total number of 155 students whi are attending the laboratory sessions. Students were asked about their preference between videos and written material (with some images), and about their preference between the three types of videos pffered: screencast (one of them including the image of the teacher and the other one with his/her voice only), and “Polimedia”. Results have shown that students prefer video files instead of written docuements when they have to prepare their laboratory sessions. Moreover, there is a statistically significant preference for the videos where the image of the professor is shown. On the other hand, despite the format of video “Poliformat” has been the best valuated, there are certain aspects to be added, as the valuation thay made of the other types of videos (which is also good), or the critrica comments on this format shown in the open question of the survey., [ES] En este trabajo se analiza la opinión de los estudiantes sobre los vídeosutilizados en la docencia inversa de prácticas de laboratorio. Se ha realizadouna encuesta con 7 preguntas de respuesta múltiple y una de respuesta abierta,contestada por 54 alumnos de los 155 que asisten al laboratorio. En ella sepregunta sobre la valoración del video frente documentos de texto e imagen,y sobre tres modelos de vídeo: dos de ellos responden al modelo de“screencast” (en uno de ellos está presente la imagen del profesor y en otrono) y el tercero es un “Polimedia”. Los resultados indican que los estudiantes,en general, prefieren archivos de video a documentos de texto para lapreparación de las prácticas de laboratorio. Además, se observa unapreferencia estadísticamente significativa a favor de los videos en los que semuestra la imagen del profesor. Por otra parte, aunque el formato de video“Polimedia” ha sido el mejor valorado, hay ciertos matices a destacar, comoes la valoración que hacen de los otros dos tipos de vídeos, que también esbuena, o los comentarios críticos con este formato mostrados en la preguntade respuesta abierta., Los autores agradecen al Instituto de Ciencias de la Educación de la universitat Politècnica de València su apoyo al grupo de Innovación e-MACAFI y al Proyecto PIME/2016/A/017.

Thermal degradation of chitosan with varying deacetylation degree (DD) ranging between 50 and 85% was analyzed by dynamic thermogravimetric analysis at different heating rates. The present study focused on the temperature range between 500 and 800 K, above water evaporation. Thermal degradation for the samples with the highest DD content showed a single degradation stage in this temperature interval while a second stage appeared in the weight derivative curves as a shoulder in the high temperature side of the main peak for the samples with the lowest DD. The Kissinger and isoconversional Ozawa-Flynn-Wall models were employed to evaluate the Ea of both thermal degradation processes. Different kinetic models were evaluated to simulate the thermogravimetry traces calculating the model parameters with a non-linear least squares fitting routine. The Sestack-Berggren model allowed reproducing accurately the overlapping of the two degradation mechanisms and calculating the mass fraction lost in each of them., The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the MAT2013-46467- C4-1-R Project, including FEDER funds. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with the assistance of the European Regional Development Fund. MAGG acknowledges a grant from the BES-2011-044740. The authors also acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4- 3-R (AEI/FEDER, UE) and from the Basque Government Industry Department under the ELKARTEK program. The authors thank the Portuguese Foundation for Science and Technology (FCT) for support in the framework of the Strategic Funding UID/FIS/04650/2013 and for the SFRH/BPD/121526/2016/ grant (DC)., info:eu-repo/semantics/publishedVersion

[EN] Chitosan/PCL block-copolymer networks were synthesized using different amounts of aldehyde end capped polycaprolactone as crosslinking agent. The crosslinking reaction was performed by dissolving both components in the common solvent hexafluoroisopropanol (HFIP). The formation of the network was confirmed by solubility tests in good solvents of both components. The resulting composition was determined by thermogravimetric analysis. The hydrophilic/hydrophobic networks behave as hydrogels; water sorption at pH7 is around 70% that of pure chitosan for a network containing 36% PCL blocks. The PCL domains were not able to crystallize, except for the CHT-64 sample as shown by DSC and X-ray diffraction. Enzymatic degradation of these networks is quite fast, thus, the network with 36% PCL presented a remaining weight of 22 +/- 1% of their initial mass after 28 days of degradation in lipase. Nevertheless in purely hydrolytic degradation, the remaining weight was 86+3% for the same time and composition., The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the MAT2013-46467-C4-1-R and MAT2016-76039-C4-1-R Project, including FEDER funds. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Institute de Salud Carlos III with the assistance of the European Regional Development Fund. MAGG acknowledges a grant from the BES-2011-044740.

[EN] Peer assessment is a form of collaborative learning where students evaluate the product of learning of other students. In our case, students perform two types of evaluation related to effective communication: they evaluate quantitatively, in teamwork, problems solved by another team, and later they evaluate qualitatively oral presentations of problem solutions. They have been given guidelines on how to perform the evaluation. The result has been compared to the assessment made by teachers. In the qualitative assessment of the oral presentations, we have not found significant differences between students and professors. Furthermore, the arguments that support evaluations are rigorous and show their learning through work done by peers, [ES] La evaluación entre compañeros es una forma de aprendizaje colaborativo en el que los estudiantes valoran el producto de aprendizaje de otros estudiantes. En nuestro caso, efectúan dos tipos de evaluación relacionados con la comunicación efectiva: en equipo evalúan cuantitativamente documentos con la resolución de problemas de otros equipos, y, posteriormente, evalúan cualitativamente las presentaciones orales de los ejercicios. Se les han dado pautas sobre como llevar a cabo la evaluación. El resultado ha sido comparado con la evaluación hecha por los profesores. En la evaluación cualitativa de las presentacions no se ha encontrado diferencias significativas entre la realizada por los alumnos en equipo y la de los profesores. Además, la argumentación que hacen a las valoraciones son rigurosas y muestran su aprendizaje a través del trabajo hecho por los compañeros., Los autores desean agradecer al Instituto de Ciencias de la Educación de la Universitat Politècnica de València (España) el apoyo al Grupo de Innovación Docente e-MACAFI y el apoyo financiero a través del proyecto PIME/2014/A025.

The aim of this study is to prove the feasibility of a system able to apply local mechanical loading on cells seeded in a hydrogel for tissue engineering applications. This experimental study is based on a previously developed artificial cartilage model with different concentrations of poly(vinyl alcohol) (PVA) that simulates the cartilage extracellular matrix (ECM). Poly(l-lactic acid) (PLLA) microspheres with dispersed magnetic nanoparticles (MNPs) were produced with an emulsion method. These microspheres were embedded in aqueous PVA solutions with varying concentration to resemble increased viscosity of growing tissue during regeneration. The ability to induce a local deformation in the ECM was assessed by applying a steady or an oscillatory magnetic field gradient to different PVA solutions containing the magnetic microparticles, similarly as in ferrogels. PLLA microparticle motion was recorded, and the images were analyzed. Besides, PVA gels and PLLA microparticles were introduced into the pores of a polycaprolactone scaffold, and the microparticle distribution and the mechanical properties of the construct were evaluated. The results of this experimental model show that the dispersion of PLLA microparticles containing MNPs, together with cells in a supporting gel, will allow applying local mechanical stimuli to cells during tissue regeneration. This local stimulation can have a positive effect on the differentiation of seeded cells and improve tissue regeneration., The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the MAT2013-46467-C4-1-R project, including the Feder funds. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. The authors thank "Servicio de Microscopia Electronica" of Universitat Politecnica de Valencia for their invaluable help. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain.

Long-term hydrolytic and enzymatic degradation profiles of poly(å-caprolactone) (PCL) networks were obtained. The hydrolytic degradation studies were performed in water and phosphate buffer solution (PBS) for 65 weeks. In this case, the degradation rate of PCL networks was faster than previous results in the literature on linear PCL, reaching a weight loss of around 20% in 60 weeks after immersing the samples either in water or in PBS conditions. The enzymatic degradation rate in Pseudomonas Lipase for 14 weeks was also studied, with the conclusion that the degradation profile of PCL networks is lower than for linear PCL, also reaching a 20% weight loss. The weight lost, degree of swelling, and calorimetric and mechanical properties were obtained as a function of degradation time. Furthermore, the morphological changes in the samples were studied carefully through electron microscopy and crystal size through X-ray diffraction. The changes in some properties over the degradation period such as crystallinity, crystal size and Young¿s modulus were smaller in the case of enzymatic studies, highlighting differences in the degradation mechanism in the two studies, hydrolytic and enzymatic., The authors would like to acknowledge the support of the Spanish Ministry of Science and Education through the DPI2010-20399-004-03 project. JM Meseguer-Duenas and A Vidaurre also would like to acknowledge the support of the CIBER-BBN, an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain

Alkaline hydrolysis of a polycaprolactone (PCL) network obtained by photopolymerization of a PCL macromer was investigated. The PCL macromer was obtained by the reaction of PCL diol with methacrylic anhydride. Degradation of PCL network is much faster than linear PCL; the weight loss rate is approximately constant until it reaches around 70%, which happens after approximately 60 h in PCL network and 600 h in linear PCL. Calorimetric results show no changes in crystallinity throughout degradation, suggesting that it takes place in the crystalline and amorphous phases simultaneously. Scanning electron microscopy microphotographs indicate that degradation is produced by a different erosion mechanism in both kinds of samples. The more hydrophilic network PCL would follow a bulk-erosion mechanism, whereas linear PCL would follow a surface-erosion mechanism. Mechanical testing of degraded samples shows a decline in mechanical properties due to changes in sample porosity as a consequence of the degradation process.

Two series of amphiphilic hydrogels of various compositions were prepared by sequentially interpenetrating two polymer networks, a poly(2-hydroxyethyl acrylate) (PHEA) network inside either a macroporous matrix of poly(methyl methacrylate) (PMMA) or a macroporous poly(ethyl acrylate) (PEA) network. In both cases poly(2-hydroxyethyl acrylate) (PHEA) served as network II, and the firstly formed porous network was a hydrophobic homonetwork, PMMA or PEA, that conferred mechanical strength to the hydrogel. In order to obtain hydrogels with high hydrophilic content, the first network was prepared in the presence of a solvent, thus yielding a macroporous network. The two families of IPNs thus obtained were: (net-PMMA)-ipn-(net-PHEA) and (net-PEA)-ipn-(net-PHEA), with a PHEA content ranging from 36% to 87% and from 64% to 94%, respectively. The novelty of the work consisted in comparing the effect of using as the first macroporous network a polymer which is glassy at room temperature (PMMA) and another of the same family (PEA) but which is in the rubber state at room temperature. Swelling studies showed that the specific equilibrium water content of PHEA falls from 1.6 for pure (unconfined) PHEA to values that range from 0.4 to 1, for the (net-PMMA)-ipn-(net-PHEA), whereas in the second IPNs family, the equilibrium water uptake of PHEA phase is, at least, the same as that of the pure PHEA (in some cases it is greater). This means that the expansion of the PHEA phase is not restricted by the confining hydrophobic component when this last is in the rubber state at room temperature. Whereas for the first IPNs the mechanical properties significantly increased (storage modulus at 37 °C from 0.25 to 2.5 GPa) compared with those of pure PHEA (25.12 MPa), little if any reinforcing effect was observed in the second type of IPNs. This is due to the fact that the glass transition of the PEA network takes place at a lower temperature than that of PHEA, so both components are in the rubbery state at room temperature. Both series behave differently also in dynamic water sorption experiments: the rigid PMMA network hinders the diffusion of water, yielding lower values of the apparent diffusion coefficients. By contrast, with the PEA polymer as network I this diffusion is similar to that of the pure PHEA homonetwork.

The effect of enzymatic degradation on poly(e-caprolactone) (PCL) films and sponges was investigated at 37 °C using Pseudomonas lipase. Film samples were prepared by the solution casting method, while sponges were obtained by the freeze extraction method. The porosity was 17 and 60% respectively. Weight loss, morphology, crystallinity and mechanical properties were studied. The kinetic study on the enzymatic degradation of PCL porous samples depends on porosity, suggesting that degradation took place on the surface, not suffering bulk degradation. The non-dependence on crystallinity indicates that degradation occurred in both phases, amorphous and crystalline, at the same time.

In this work polymeric scaffolds with macropores in the shape of cylindrical channels aligned in a microporous polymer matrix were obtained. Polymer networks of different hydrophilicity were obtained with the same pore architecture: poly(hydroxyethyl methacrylate) (representative of a very hydrophilic polymer), poly(ethyl acrylate) (hydrophobic) and poly(ethyl acrylate-co-hydroxyethyl methacrylate) (a 50/50 random co-polymer with intermediate hydrophilicity) net-P(EA-co-HEMA). The macroporous structure was obtained by using poly(acrylonitrile) fibres as porogen, while the microporous matrix was produced by phase separation during polymerisation of the monomers diluted in ethanol. Morphology, equilibrium water content and water diffusion properties of the macroporous sponges are compared with the corresponding non-porous networks. The pores collapse when ethanol is evaporated from the swollen samples at room temperature. The pores of the PHEMA hydrogels reopen when the samples are immersed in liquid water, but this does not occur in the hydrophobic networks. Nevertheless, progressive substitution of ethanol by water produces PEA and co-polymer samples swollen in water with an open pore structure.

Synthetic porous hydrogels are becoming more and more important in the field of biomaterials. Different studies demonstrate that the porous structure promotes the colonisation of living cells and improves the biocompatibility of the implants. The macroporous structure allows not only the control of cellular ingrowth morphology but also the mechanical integration and the regulation of nutrient and hydraulic flow in the hydrogel. In this work poly(ethyl acrylate-co-hydroxyethyl methacrylate) (PEA/PHEMA) copolymers were polymerized using 2% of ethylene glycol dimethacrylate as cross-linking agent and azoisobotyronitrile as initiator. Five samples were prepared with the EA/HEMA weight ratios of 75/25, 50/50, 25/75 and pure PEA and PHEMA polymers, obtaining different degrees of hydrophilicity. The macroporous structure was obtained by adding poly(acrylonitrile) fibres to the monomers. After polymerization the fibres were eliminated by dissolution in dimethyl formamide. The holes are cylinders of approximately 40μm diameter and are all, more or less, in the same direction, although they are not uniformly distributed. Water sorption isotherms and diffusion properties of the macroporous samples are compared with the samples without holes.

In our experience of teaching physics for engineering at university level we have learned that the mathematical relationships between the parameters that control a process are important, but not sufficient, to understand a process. Such knowledge will only be consolidated if the new concept is incorporated by student in his field of study. Simulation programs, especially through visualization, can help to attain this target. We have developed three programs using Visual Basic. One of them is devoted to fitting experimental data and is complementary to experimental work; the others focus on dynamics, translation, and rotational movement, helping to understand the Newton's laws. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 45–49, 2002; Published online in Wiley InterScience (www.interscience.wiley.com.); DOI 10.1002/cae.10016

[EN] A poly(L-lactic acid) scaffold prepared by a combination of freeze-extraction and porogen-leaching methods was submitted to static degradation in a phosphate-buffered saline solution at pH 7.4 and 37 C for up to 12 months. After 6 months of degradation, the scaffold maintained its integrity, although noticeable changes in its permeability and pore size were recorded. After 12 months, scanning electron microscopy pictures showed that most of the trabeculae were broken, and the sample disaggregated under minimum loading. Neither weight loss nor crystallinity changes in the first heating calorimetric scan were observed during the degradation experiment. However, after 12 months, a rise in the crystallinity from 13 to 38% and a drop in the glass-transition temperature from 58 to 54 C were measured in the second heating scan. The onset of thermal degradation moved from 300 to 210 C after 12 months. Although the elastic modulus suffered only a very slight reduction with degradation time, the aggregate modulus decreased 44% after 6 months., The authors acknowledge the support of the Instituto de Salud Carlos III, Ministerio de Economıa y Competitividad, and the European Commission through FP7-ERANet EuroNanoMed 2011 PI11/03032 and FP7-PEOPLE-2012-IAPP (contract grant number PIAP-GA-2012–324386). The Biomedical Research Networking Center in Bioengineering, Biomaterials, and Nanomedicine is an initiative funded by the VI National R&D&i Plan 2008–2011, Iniciativa Ingenio 2010, and Consolider Program. Biomedical Research Networking Center actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. The authors also thank the Tissue Characterization Platform of the Biomedical Research Networking Center in Bioengineering, Biomaterials, and Nanomedicine for its technical support. They also thank the Linguistic Assistance Services of the Language Centre, Universitat Politecnica de Valencia, for their help in revising this article.

Thermal degradation of as-electrospun chitosan membranes and samples subsequently treated with ethanol and cross-linked with glutaraldehyde has been studied by thermogravimetry (TG) coupled with an infrared spectrometer. The influence of the electrospinning process and cross-linking in the electrospun chitosan thermal stability was evaluated. Up to three degradation steps were observed in the TG data, corresponding to water dehydration reaction at temperatures below 100 °C, loss of side groups formed between the amine groups of chitosan and trifluoroacetic acid between 150 and 270 °C and chitosan thermal degradation that starts around 250 °C and goes up to 400 °C. The Kissinger model was employed to evaluate the activation energies of the electrospun membranes during isothermal experiments and revealed that thermal degradation activation energy increases for the samples processed by electrospinning and subsequent neutralization and cross-linking treatments with respect to the neat chitosan powder., This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011 and PEST-C/QUI/UIO686/2011. The authors also thank funding from "Matepro-Optimizing Materials and Processes", ref. "NORTE-07-0124-FEDER-000037", co-funded by the "Programa Operacional Regional do Norte" (ON.2 - O Novo Norte), under the "Quadro de Referencia Estrategico Nacional" (QREN), through the "Fundo Europeu de Desenvolvimento Regional" (FEDER). The authors also thank support from the COST Action MP1003 - "European Scientific Network for Artificial Muscles", MP1206 "Electrospun Nano-fibres for bio inspired composite materials and innovative industrial applications" and MP1301 "New Generation Biomimetic and Customized Implants for Bone Engineering". DMC and VS thank the FCT for the SFRH/BD/82411/2011 and SFRH/BPD/63148/2009 grants, respectively. JLGR and MAGG acknowledge the support of the Spanish Ministry of Science and Innovation through project no. MAT2010-21611-C03-01 and MAGG the BES-2011-044740 grant. CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.

Blends of polycarbonate (PC) and poly(acrylonitrile-co-butadiene-co-styrene) (ABS) with different compositions are characterized by means of dynamic mechanical measurements. The samples show phase separation. The shift in the temperatures of the main dynamic mechanical relaxation shown by the blend with respect to those of the pure components is attributed to the migration of oligomers present in the ABS toward the PC in the melt blending process. A comparison with other techniques (dielectric and calorimetric analysis) and the application of the Takayanagi three block model confirm this hypothesis. In all the studied blend compositions (ABS weight up to 28.6%) the PC appears as the matrix where a disperse phase of ABS is present. The scanning and transmission electron microscopy micrographs show that the size of the ABS particles increases when the proportion of ABS in the blend increases. The FTIR results indicate that the interaction between both components are nonpolar in nature and can be enhanced by the preparation procedure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1507–1516, 2002