Assessment of head injury risk caused by impact using finite element models

[ES] Las cargas de impacto son la fuente primaria de lesiones en la cabeza y pueden resultar en un rango de traumatismo desde leve hasta severo. Debido a la existencia de múltiples entornos en los que se pueden desencadenar lesiones por impacto (accidentes automovilísticos, deportes, caídas accidentales, violencia), éstas pueden afectar potencialmente a toda la población independientemente de su estado de salud. Pese al creciente esfuerzo en investigación para comprender la biomecánica de las lesiones por traumatismo en la cabeza, todavía no es del todo posible realizar predicciones precisas ni prevenir estos eventos. En esta Tesis, se han estudiado algunos aspectos del comportamiento ante impacto de los diferentes tejidos biológicos involucrados mediante el desarrollo de un modelo numérico de cabeza humana a partir de imágenes de tomografía computerizada (TAC). Se han realizado simulaciones en elementos finitos (EF) de ensayos experimentales de la literatura con el fin de validar el modelo numérico desarrollado, estableciendo unas propiedades mecánicas adecuadas para cada uno de sus constituyentes. De esta manera se puede adquirir una predicción adecuada del riesgo de sufrir daños. Parte de esta Tesis se centra en el entorno balístico, específicamente en cascos de combate antibalas, los cuales son susceptibles de causar traumatismo craneoencefálico debido a la elevada deformación que sufren durante el impacto. Previamente al estudio de estos fenómenos de alta velocidad, se han realizado ensayos experimentales y numéricos para caracterizar la respuesta mecánica de algunos materiales compuestos ante impacto de baja velocidad. Al principio de esta Tesis se ha realizado una revisión del estado del arte acerca de los criterios existentes para cuantificar el trauma craneoencefálico.Este es un aspecto clave para las simulaciones numéricas, ya que la idoneidad de algunos de estos criterios para la predicción de lesiones cerebrales todavía es un debate abierto. Mediante EF se han realizado simulaciones de impactos balísticos en una cabeza protegida con un casco de combate. Mediante la posterior aplicación de diferentes criterios de daño sobre los resultados obtenidos se ha evaluado el nivel de protección que aseguran los protocolos de aceptación de cascos de combate, así como las estrategias para determinar su tallaje. Se ha demostrado que las normativas existentes para cascos de combate son capaces de mitigar algunos mecanismos de trauma pero no logran prevenir otros como los gradientes de presión intracraneales. Además, se ha demostrado que algunas de las estrategias de tallaje más comúnmente adoptadas por los fabricantes, como producir un solo tamaño de calota, deberían ser reconsideradas ya que existe un mayor riesgo de traumatismo cuando la distancia entre la cabeza y la calota del casco no es suficiente. Siguiendo la línea de protecciones personales, algunos de los materiales compuestos comúnmente empleados en la industria armamentística se han combinado para crear distintas configuraciones de calota para optimizar la relación entre peso del casco y protección para la cabeza. Materiales ligeros como el UHMWPE han resultado en un comportamiento menos eficiente que el de los apilados de tejido de aramida a la hora de limitar la BFD (deformación máxima en la calota del casco en la zona de impacto). Hacia el final de la Tesis se presenta un modelo numérico de cabeza humana detallado, que incluye treinta y tres de las estructuras anatómicas principales. Dicho modelo se ha desarrollado para la simulación de un accidente ecuestre en el que aparecen múltiples lesiones craneoencefálicas. Principalmente, se pretende establecer un criterio mecánico para predecir el hematoma subdural (HS) basado en la ruptura de los vasos sanguíneos intracraneales. Se ha propuesto un valor umbral de ruptura en tensiones de 3.5 MPa, pero tanto este límite como la localización del vaso dañado son altamen[CA] Les càrregues d'impacte son la font primària de lesions al cap i poden resultar en un rang de severitat des de lleu a greu. Degut als múltiples entorns en que poden desencadenar-se lesions per impacte (accidents automobilístics, esports, caigudes accidentals, violència), aquestes poden afectar potencialment a tota la població independentment del seu estat de salut. Malgrat el creixent esforç en investigació per comprendre la biomecànica de les lesions per traumatisme al cap, encara no és del tot possible realitzar prediccions precises ni prevenir aquestos esdeveniments. En aquesta Tesi, s'han estudiat alguns aspectes del comportament a impacte dels diferents teixits biològics involucrats mitjançant el desenvolupament d'un model numèric de cap humà a partir d'imatges de tomografia computeritzada (TAC). S'han realitzat simulacions en elements finits (EF) d'assajos experimentals de la literatura amb la finalitat de validar el model numèric desenvolupat, establint unes propietats mecàniques adequades per a cadascun dels seus constituents. D'aquesta manera es pot aconseguir una predicció del risc de sofrir danys traumàtics. Part d'aquesta Tesi es centra en l'entorn balístic, específicament en cascs de combat antibales, els quals són susceptibles de causar traumatisme degut a l'elevada deformació que sofrixen durant l'impacte. Previament a l'estudi d'aquests fenòmens d'alta velocitat, s'han realitzat assajos experimentals i numèrics per a caracteritzar la resposta mecànica d'alguns materials compostos en condicions d'impacte a baixa velocitat. Al començament d'aquesta Tesi s'ha realitzat una revisió de l'estat de l'art sobre els criteris existents per quantificar el trauma cranioencefàlic. Aquest és un aspecte clau per a les simulacions numèriques, ja que l'utilitat d'alguns d'aquestos criteris per a la predicció de lesions cerebrals és encara un debat obert. Mitjançant EF s'han realitzat simulacions numèriques d'impactes balístics en un cap protegit amb un casc de combat. Gràcies a la posterior aplicació de diferents criteris de dany sobre els resultats obtinguts s'ha evaluat el nivell de protecció que asseguren els protocols d'acceptació de cascs de combat, així com les estratègies per a determinar les seues talles. S'ha demostrat que les normatives existents són capaces de mitigar alguns mecanismes de trauma però no aconseguixen prevenir altres com els gradients de pressions intracranials. A més, s'ha demostrat que algunes estratègies per determinar les talles més comunament adoptades pels fabricants (com produir només un tamany de calota i adaptar el gruix de les escumes interiors a les diferents dimensions dels subjectes) haurien de ser reconsiderades ja que existeix un major risc de traumatisme quan la distància entre el cap i la calota del casc no és suficient. Seguint la línia de proteccions personals, alguns dels materials compostos comunament utilitzats en la indústria de l'armament s'han combinat per a crear distintes possibles configuracions de calota amb la finalitat d'optimitzar la relació entre pes i protecció. Materials lleugers com l'UHMWPE han resultat en un comportament menys eficient que el d'apilats de teixit d'aramida a l'hora de limitar la BFD (deformació màxima a la calota del casc a la zona d'impacte). Cap al final de la Tesi es presenta un model numèric detallat de cap humà, que inclou trenta-tres de les estructures anatòmiques principals. Aquest model s'ha desenvolupat per a la simulació d'un accident eqüestre en el qual apareixen múltiples lesions cranioencefàliques. Principalment, es pretén establir un criteri mecànic per a la predicció de l'hematoma subdural (HS) basat en la ruptura dels vasos sanguinis intracranials. S'ha proposat un valor umbral de ruptura en tensions de 3.5 MPa, pero tant aquest límit com la ubicació del vas danyat són altament dependents de l'anatomia específica de cada subjecte.[EN] Impact loading is the primary source of head injuries and can result in a range of trauma from mild to severe. Because of the multiple environments in which impact-related injuries can take place (automotive accidents, sports, accidental falls, violence), they can potentially affect the entire population regardless of their health conditions. Despite the increasing research effort on the understanding of head impact biomechanics, accurate prediction and prevention of traumatic injuries has not been completely achieved. In this Thesis, some aspects of the impact behaviour of the different biological tissues involved have been analysed through the development of a numerical human head model from Computed Tomography (CT) images. FE simulations of experimental tests from the literature have been performed and enhanced the validation of the head model through the establishment of proper material laws for its constituents, which enable adequate prediction of injury risks. Part of this Thesis focuses on the ballistic environment, especifically in bulletproof composite helmets, which are susceptible to cause blunt injuries to the head because of their large deformation during impact. Prior to the study of these high-speed impacts, experimental tests and finite element (FE) models have been performed to characterise the mechanical response of composite materials subjected to low velocity impact. The implementation of a continuum damage mechanics approach coupled to a Hashin failure criterion and surface-to-surface cohesive relations to the numerical model provided a good matching with the impact behaviour obtained experimentally, capturing the principal damage mechanisms. A review of the head injury criteria currently available in the literature has been performed at the beginning of this Thesis. This is a key issue for the numerical simulations, as the suitability of some criteria to predict head injuries is still an open question. Numerical simulation of ballistic impacts on a human head protected with a combat helmet has been conducted employing explicit FE analysis. The level of protection ensured by helmet acceptance protocols as well as their sizing strategies have been studied and discussed by means of the application of different mechanical-based head injury criteria. It has been demonstrated that current helmet testing standards do mitigate some specific forms of head trauma but fail to prevent other injury mechanisms such as the intracranial pressure gradients within the skull. Furthermore, it has been demonstrated that some well-established helmet sizing policies like manufacturing one single composite shell and adapting the thickness of the interior pads to the different head dimensions should be reconsidered, as there is a great risk of head injury when the distance between the head and the helmet shell (stand-off distance) is not sufficient. Following the line of personal protections, some composite materials commonly employed in the soft body armour industry have been combined into different helmet shells configurations to optimise the ratio of weight-to-head protection. Light materials like UHMWPE appear to be less efficient than integral woven-aramid lay-ups in the limitation of the backface deformation (BFD), the maximum deformation sustained by the helmet at the impact site. A detailed head numerical model including thirty-three of its main anatomical structures has been developed for the simulation of an equestrian accident that resulted in many head injuries. Above all, the establishment of a mechanical criterion for the prediction of subdural hematona (SDH) based on the rupture of the head blood vessels is intended. A stress threshold for vein rupture has been set on 3.5 MPa, but both this limit and the location of vessel failure are highly dependent on the specific anatomy of the subject's vascularity.Palomar Toledano, M. (2019). Assessment of head injury risk caused by impact using finite element models [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/135254TESI

Doped Electrospinned Material-Guides High Efficiency Regional Bone Regeneration

Grant PID2020-114694RB-I00 funded by MCIN/AEI 10.13039/501100011033. M.T.-O. is Fellow FPU of Ministry of Universities [grant FPU20/0045].The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/polym15071726/s1The main target of bone tissue engineering is to design biomaterials that support bone regeneration and vascularization. Nanostructured membranes of (MMA)1-co-(HEMA)1/(MA)3- co-(HEA)2 loaded with 5% wt of SiO2-nanoparticles (Si-M) were doped with zinc (Zn-Si-M) or doxycycline (Dox-Si-M). Critical bone defects were effectuated on six New Zealand-bred rabbit skulls and then they were covered with the membranes. After six weeks, a histological analysis (toluidine blue technique) was employed to determine bone cell population as osteoblasts, osteoclasts, osteo- cytes, M1 and M2 macrophages and vasculature. Membranes covering the bone defect determined a higher count of bone cells and blood vessels than in the sham group at the top regions of the defect. Pro-inflammatory M1 appeared in a higher number in the top regions than in the bottom regions, when Si-M and Dox-Si-M were used. Samples treated with Dox-Si-M showed a higher amount of anti-inflammatory and pro-regenerative M2 macrophages. The M1/M2 ratio obtained its lowest value in the absence of membranes. On the top regions, osteoblasts were more abundant when using Si-M and Zn-Si-M. Osteoclasts were equally distributed at the central and lateral regions. The sham group and samples treated with Zn-Si-M attained a higher number of osteocytes at the top regions. A preferential osteoconductive, osteoinductive and angiogenic clinical environment was created in the vicinity of the membrane placed on critical bone defects.MCIN/AEIFPU of Ministry of Universities FPU20/004

Short versus standard implants at sinus augmented sites: a systematic review and meta‑analysis

Background Short implants are proposed as a less invasive alternative with fewer complications than standard implants in combination with sinus lift. The aim of this systematic review and meta-analysis was to state the efficacy of placing short implants (≤ 6 mm) compared to standard-length implants (≥ 8 mm) performing sinus lift techniques in patients with edentulous posterior atrophic jaws. Efficacy will be evaluated through analyzing implant survival (IS) and maintenance of peri-implant bone (MBL). Methods Screening process was done using the National Library of Medicine (MEDLINE by PubMed), EMBASE, the Cochrane Oral Health, and Web of Science (WOS). The articles included were randomized controlled trials. Risk of bias was evaluated according to The Cochrane Collaboration’s tool. Weighted means were calculated. Heterogeneity was determined using Higgins (I2). A random-effects model was applied. Secondary outcomes such as surgical time, patient satisfaction, mucositis and peri-implantitis, pain, and swelling were analyzed. Results Fourteen studies (597 patients and 901 implants) were evaluated. IS was 1.02 risk ratio, ranging from 1.00 to 1.05 (CI 95%) (p = 0.09), suggesting that IS was similar when both techniques were used. MBL was higher in patients with standard-length implants plus sinus lift elevation (p = 0.03). MBL was 0.11 (0.01–0.20) mm (p = 0.03) and 0.23 (0.07–0.39) mm (p = 0.005) before and after 1 year of follow-up, respectively, indicating that the marginal bone loss is greater for standard-length implants. Discussion Within the limitations of the present study, as relatively small sample size, short dental implants can be used as an alternative to standard-length implants plus sinus elevation in cases of atrophic posterior maxilla. Higher MBL was observed in the groups where standard-length implants were used, but implant survival was similar in both groups. Moreover, with short implants, it was observed a reduced postoperative discomfort, minimal invasiveness, shorter treatment time, and reduced costs. Clinical Clinical relevance The low MBL promoted by short implants does contribute to a paradigm shift from sinus grafting with long implants to short implants. Further high-quality long-term studies are required to confirm these findings.Spanish GovernmentEuropean Commission PID2020-114694RB-I00 MINECO/AEI/FEDER/U

La comunicación como estudio transversal: evolución de las facultades especializadas en España

The digital transformation has caused an unpreceded revolution in the communication industry. This new scenario has led to the appearance of new multipurpose and versatile professional profiles, that now incorporate humanistic and technical skills. These skills have been influenced by current technological developments and include a global vision as well as an interdisciplinary approach. Therefore, the Communication faculties have had to update their education programs to satisfy the demand of the professional world, which has become more and more changeable. At the same time, the digital transformation was boosted by the 2008 economic crisis, and it was necessary to update study programs to promote the employability of graduates. This paper presents the current map of Communication faculties in Spain and analyzes the reason for the denominations given to these centers, which today are quite distant from the original ones in 1971, and it places a special focus on hybrid faculties, those that have in their name the fusion of Communication with another area of knowledge. By reviewing its academic offer and areas of research, the article intends to find out if the new positioning helps to adapt the training communicators receive to the needs of the current society.La transformación digital ha provocado una verdadera revolución en la industria de la comunicación. Este nuevo escenario ha originado la aparición de nuevos profesionales polivalentes y versátiles, que incorporan competencias humanísticas y técnicas, y que deben tener una visión global y una formación interdisciplinar. Además, la comunicación en sí se ha transformado en un eje de estudio transversal. En consecuencia, las facultades de Comunicación españolas han tenido que actualizar su formación con vistas a satisfacer la demanda del mundo profesional, cada vez más cambiante. A su vez, la crisis económica de 2008 aceleró esa transformación y se hace necesario que los planes de estudio estén actualizados para fomentar la empleabilidad. Este artículo presenta el mapa actual de facultades de Comunicación en España, analiza el porqué de las denominaciones de sus centros, cada vez más alejadas de las que adoptaron las primeras facultades en 1971 y se centra en las facultades híbridas, aquellas que anuncian en su concepción la fusión de la Comunicación con otra área de conocimiento. Mediante la revisión de su oferta académica, de las líneas de investigación y de la entrevista a sus decanos se pretende averiguar si el nuevo posicionamiento favorece la formación de los nuevos comunicadores

The Collagen Origin Influences the Degradation Kinetics of Guided Bone Regeneration Membranes

This work was supported by: (1) the Ministry of Economy and Competitiveness and European Regional Development Fund [Project PID2020-114694RB-100 MINECO/AEI/FEDER/UE], (2) University of Granada/Regional Government of Andalusia Research Fund from Spain and European Regional Development Fund (A-BIO-157-UGR-18/FEDER).Collagen membranes are currently the most widely used membranes for guided bone regeneration; however, their rapid degradation kinetics means that the barrier function may not remain for enough time to permit tissue regeneration to happen. The origin of collagen may have an important effect on the resistance to degradation. The aim of this study was to investigate the biodegradation pattern of five collagen membranes from different origins: Biocollagen, Heart, Evolution X-fine, CopiOs and Parasorb Resodont. Membranes samples were submitted to different degradation tests: (1) hydrolytic degradation in phosphate buffer saline solution, (2) bacterial collagenase from Clostridium histolyticum solution, and (3) enzyme resistance using a 0.25% porcine trypsin solution. Immersion periods from 1 up to 50 days were performed. At each time point, thickness and weight measurements were performed with a digital caliper and an analytic microbalance, respectively. ANOVA and Student–Newman–Keuls tests were used for comparisons (p < 0.05). Differences between time-points within the same membranes and solutions were assessed by pair-wise comparisons (p < 0.001). The Evolution X-fine collagen membrane from porcine pericardium attained the highest resistance to all of the degradation tests. Biocollagen and Parasorb Resodont, both from equine origin, experienced the greatest degradation when immersed in PBS, trypsin and C. histolyticum during challenge tests. The bacterial collagenase solution was shown to be the most aggressive testing method.Ministry of Economy and Competitiveness PID2020-114694RB-100European Commission PID2020-114694RB-100 A-BIO-157-UGR-18/FEDERUniversity of Granada/Regional Government of Andalusia Research Fund from Spain A-BIO-157-UGR-18/FEDE

In Vitro Biodegradation Pattern of Collagen Matrices for Soft Tissue Augmentation

This work was supported by: (1) the Ministry of Economy and Competitiveness and the European Regional Development Fund (Project PID2020-114694RB-100 MINECO/AEI/FEDER/UE), (2) the University of Granada/Regional Government of Andalusia Research Fund from Spain, and the European Regional Development Fund (A-BIO-157-UGR-18/FEDER). This research is part of C.V.'s PhD research study.Collagen matrices have become a great alternative to the use of connective tissue grafts for soft tissue augmentation procedures. One of the main problems with these matrices is their volume instability and rapid degradation. This study has been designed with the objective of examining the degradation of three matrices over time. For this purpose, pieces of 10 10 mm2 of Fibro-Gide, Mucograft and Mucoderm were submitted to three different degradation tests— (1) hydrolytic degradation in phosphate buffer solution (PBS); (2) enzyme resistance, using a 0.25% porcine trypsin solution; and (3) bacterial collagenase resistance (Clostridium histolyticum)—over different immersion periods of up to 50 days. Weight measurements were performed with an analytic microbalance. Thickness was measured with a digital caliper. A stereomicroscope was used to obtain the matrices’ images. ANOVA and Student–Newman–Keuls tests were used for mean comparisons (p < 0.05), except when analyzing differences between time-points within the same matrix and solution, where pair-wise comparisons were applied (p < 0.001). Fibro-Gide attained the highest resistance to all degradation challenges. The bacterial collagenase solution was shown to constitute the most aggressive test as all matrices presented 100% degradation before 14 days of storage.Ministry of Economy and CompetitivenessEuropean Commission PID2020-114694RB-100 A-BIO-157-UGR-18/FEDERUniversity of Granada/Regional Government of Andalusia Research Fund from Spai

Modelado mediante elementos finitos del impacto en elementos de protección personal fabricados con materiales compuestos

Este trabajo se basa en la simulación numérica de impactos balísticos sobre un modelo de elementos finitos compuesto por un casco de combate y una cabeza humana. El objetivo del trabajo es evaluar la respuesta de un casco de combate de aramida y de los tejidos vivos de la cabeza humana ante diferentes condiciones de impacto balístico. Para simular el impacto se emplea un módulo de cálculo explícito con integración directa y se obtiene la respuesta cinemática de los cuerpos involucrados y la energía absorbida por éstos, así como otros parámetros ingenieriles. El modelo numérico de cabeza humana se obtiene a partir de la segmentación de imagen médica, y se valida mediante la recreación de ensayos experimentales obtenidos de la literatura. De esta manera es posible aportar sugerencias para el diseño y la metodología de aceptación de los cascos de combate actuales de manera que garanticen una protección y unas prestaciones requeridas.Palomar Toledano, M. (2017). Modelado mediante elementos finitos del impacto en elementos de protección personal fabricados con materiales compuestos. Universitat Politècnica de València. http://hdl.handle.net/10251/87481TFG

Effect of different helmet shell configurations on the protection against head trauma

[EN] Head trauma following a ballistic impact in a helmeted head is assessed in this work by means of finite element models. Both the helmet and the head models employed were validated against experimental high-rate impact tests in a previous work. Four different composite ply configurations were tested on the helmet shell, and the energy absorption and the injury outcome resulting from a high-speed impact with full metal jacket bullets were computed. Results reveal that hybrid aramid-polyethylene configurations do not prevent bullet penetration at high velocities, while 16-layer aramid configurations are superior in dissipating the energy absorbed from the impact. The fabric orientation of these laminates proved to be determinant for the injury outcome, as maintaining the same orientations for all the layers led to basilar skull fractures (dangerous), while alternating orientation of the adjacent plies resulted in an undamaged skull. To the authors knowledge, no previous work in the literature has analysed numerically the influence of different stack configurations on a single combat helmet composite shell on human head trauma.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study received the funding support from the Spanish Ministry of Economy and Competitiveness in the framework of the projects DPI2013-46641-R and DPI2017-89197-C2-2-R and the Generalitat Valenciana in the context of the Programme PROMETEO 2016/007.Palomar-Toledano, M.; Belda R.; Giner Maravilla, E. (2019). Effect of different helmet shell configurations on the protection against head trauma. Journal of Strain Analysis for Engineering Design. 54(7-8):408-415. https://doi.org/10.1177/0309324719835706S408415547-

Ensemble harbour forecast performance

Deliverable D3.3 del Proyecto MyWave: A pan-European concerted and integrated approach to operational wave modelling and forecasting – a complement to GMES MyOcean services. Work programme topic: SPA.2011.1.5.03 – R&D to enhance future GMES applications in the Marine and Atmosphere areas.Funded under: FP7-SPACE-2011-284455

Collagen Matrix vs. Autogenous Connective Tissue Graft for Soft Tissue Augmentation: A Systematic Review and Meta-Analysis

This work was supported by: (1) the Ministry of Economy and Competitiveness and European Regional Development Fund [Project MAT2017-85999-P MINECO/AEI/FEDER/UE], (2) University of Granada/Regional Government of Andalusia Research Fund from Spain and European Regional Development Fund (A-BIO-157-UGR-18/FEDER). This research is part of C.V.'s PhD research study.Soft tissues have been shown to be critical for the maintenance of both teeth and implants. Currently, regenerative soft tissue techniques propose the use of collagen matrices, which can avoid the drawbacks derived from the obtainment of autogenous tissue graft. A systematic review and meta-analysis were conducted to ascertain the efficacy of collagen matrices (CM) compared to autogenous connective tissue graft (CTG) to improve soft tissue dimensions. An electronic and manual literature searches were performed to identify randomized clinical trials (RCT) or controlled clinical trials (CCT) that compared CTG and CM. Pooled data of width of keratinized tissue (KT) and mucosal thickness (MT) were collected and weighted means were calculated. Heterogeneity was determined using Higgins (I-2). If I-2 > 50% a random-effects model was applied. Nineteen studies were included based on the eligibility criteria. When using CTG a higher MT gain (0.32 mm, ranging from 0.49 to 0.16 mm) was obtained than when employing CM. Similar result was obtained for the width of KT gain, that was 0.46 mm higher (ranging from 0.89 to 0.02 mm) when employing CTG. However, it can be stated that, although autogenous CTG achieves higher values, CM are an effective alternative in terms of total width of KT and MT gain.Ministry of Economy and Competitiveness MAT2017-85999-P MINECO/AEI/FEDER/UEEuropean Commission MAT2017-85999-P MINECO/AEI/FEDER/UE A-BIO-157-UGR-18/FEDERUniversity of Granada/Regional Government of Andalusia Research Fund from Spai