Hari metalikoetan eta arku elektrikoan oinarritutako fabrikazio-gehigarriko WAAM teknologiaren oinarriak eta aplikazioak

Additive Manufacturing (AM) is a new production concept based on the formation of parts layer by layer. Thanks to its nature, the design limitations imposed by traditional manufacturing techniques can be overcome. Although, parts can be manufactured in many different types of materials utilizing this technology, this paper will only focused on additive manufacturing techniques based on metallic materials. These techniques can be classified into three main groups: Powder Bed Fusion (PBF), Powder Feed Systems (PFS) and Wire Feed Systems (WFS). Due to the advantages it presents, special attention will be paid to the Wire Arc Additive Manufacturing (WAAM) technique classified within the WFS techniques. Among its characteristics, the most significant is the high deposition rate that it offers which allows the manufacture of large parts. In addition, compared with traditional manufacturing techniques the amount of material used is reduced and therefore a high efficiency of material usage is achieved obtaining preforms close to the final part that must be machined. WAAM technology also enables the manufacturing of parts in any weldable wire-like metallic material. Thus, the price of a kilogram of material in wire format is much cheaper than the powder used by certain additive manufacturing techniques. This work will also describe various real use cases focused on each application area (direct manufacturing, indirect manufacturing and repair).; Fabrikazio-gehigarria geruzaz geruza piezak eratzean oinarritzen den produkzio-kontzeptu berria da. Fabrikazio-gehigarriaren barneko teknikek duten izaera dela eta, orain artean fabrikazio-teknika tradizionalek inposatutako diseinu-mugak gainditzea ahalbidetzen dute. Material mota anitzetan lan egin dezaketen arren, lan honetan material metalikoetan oinarritutako fabrikazio-gehigarriko teknikak azalduko dira. Horien artetik, arku eta hari bidezko fabrikazio gehigarrian (ingelesez, Wire Arc Additive Manufacturing (WAAM)) arreta berezia ezarriko da, erakusten dituen abantailak direla eta. Lan honen helburu nagusia WAAM teknologia metalen fabrikazio-gehigarriaren barruan kokatzea da, teknologia honen deskribapena eginez eta hark industrian dituen hainbat aplikazio azalduz. Horretarako, lehenik eta behin, metalen fabrikazio-gehigarriko prozesu nagusiak azalduko dira, eta materiala elikatzeko eraren araberako sailkapen bat aurkeztuko da. Ondoren, WAAM prozesuaren deskribapena eta xehetasunak azalduko dira. Jarraian, WAAM teknologiaren bidez piezak fabrikatzeko erabilitako ekipamendua eta aplikazio eremu bakoitzeko (fabrikazio zuzena, ez-zuzena eta konponketak) adibide industrial erreal bat azalduko da. Fabrikazio zuzenean, 5356 aluminio-aleazioan topologikoki optimizatutako diseinua duen dorrearen fabrikazioa azalduko da, diseinu originalarekin alderatuta % 31ko pisu aurrezkia lortuz. Fabrikazio ez-zuzenean, ER70S-6 altzairuan tamaina handiko molde baten fabrikazioa aipatuko da. Azkenik, konponketei dagokienez, H13 altzairuzko molde higatu bat WAAM teknologiaren bidez nola konpondu den azalduko da

Crystallization Behavior and Mechanical Properties of Poly(ε-caprolactone) Reinforced with Barium Sulfate Submicron Particles

Poly(ε-caprolactone) (PCL) was mixed with submicron particles of barium sulfate to obtain biodegradable radiopaque composites. X-ray images comparing with aluminum samples show that 15 wt.% barium sulfate (BaSO4) is sufficient to present radiopacity. Thermal studies by differential scanning calorimetry (DSC) show a statistically significant increase in PCL degree of crystallinity from 46% to 52% for 25 wt.% BaSO4. Non-isothermal crystallization tests were performed at different cooling rates to evaluate crystallization kinetics. The nucleation effect of BaSO4 was found to change the morphology and quantity of the primary crystals of PCL, which was also corroborated by the use of a polarized light optical microscope (PLOM). These results fit well with Avrami–Ozawa–Jeziorny model and show a secondary crystallization that contributes to an increase in crystal fraction with internal structure reorganization. The addition of barium sulfate particles in composite formulations with PCL improves stiffness but not strength for all compositions due to possible cavitation effects induced by debonding of reinforcement interphase.The work was financially supported by funding from the Basque Government Department of Education, Linguistic Politics and Culture for a consolidated research group project IT-927-16 and the Spanish Government´s MINECO MAT2016-78527-P (AEI/FEDER,UE). H.A. thanks the predoctoral grant received from the University of the Basque Country (UPV/EHU)

3D zelula-euskarri biodegradagarriak: diseinuaren garrantzia etorkizuneko biomedikuntza-aplikazioetan

Azken urte hauetan, polimero biodegradagarriez eginiko 3D zelula-euskarrien diseinuak garrantzi handia hartu du ehun-ingeniaritza arloaren barnean. Lan honen helburu nagusia da gai honi buruzko ikuspegi orokor bat ematea. Alde batetik, euskarriaren diseinuan polimero biodegradagarriaren hautapenak, mikroegiturak eta euskarriaren morfologiak duten garrantzia azaltzen da. Bestetik, atal honetan euskarriak lortzeko metodo ezberdinak ere deskribatzen dira. Bukatzeko, zelulen eta polimero-euskarriaren arteko elkarrekintzen ikerketak etorkizuneko medikuntza-aplikazioetarako duen garrantzia goraipatzen da

Self-assembled three-dimensional hydrogels based on graphene derivatives and cerium oxide nanoparticles: scaffolds for co-culture of oligodendrocytes and neurons derived from neural stem cells

Stem cell-based therapies have shown promising results for the regeneration of the nervous system. However, the survival and integration of the stem cells in the neural circuitry is suboptimal and might compromise the therapeutic outcomes of this approach. The development of functional scaffolds capable of actively interacting with stem cells may overcome the current limitations of stem cell-based therapies. In this study, three-dimensional hydrogels based on graphene derivatives and cerium oxide (CeO2) nanoparticles are presented as prospective supports allowing neural stem cell adhesion, migration and differentiation. The morphological, mechanical and electrical properties of the resulting hydrogels can be finely tuned by controlling several parameters of the self-assembly of graphene oxide sheets, namely the amount of incorporated reducing agent (ascorbic acid) and CeO2 nanoparticles. The intrinsic properties of the hydrogels, as well as the presence of CeO2 nanoparticles, clearly influence the cell fate. Thus, stiffer adhesion substrates promote differentiation to glial cell lineages, while softer substrates enhance mature neuronal differentiation. Remarkably, CeO2 nanoparticle-containing hydrogels support the differentiation of neural stem cells to neuronal, astroglial and oligodendroglial lineage cells, promoting the in vitro generation of nerve tissue grafts that might be employed in neuroregenerative cell therapies

3D zelula-euskarri biodegradagarriak: diseinuaren garrantzia etorkizuneko biomedikuntza-aplikazioetan

Azken urte hauetan, polimero biodegradagarriez eginiko 3D zelula-euskarrien diseinuak garrantzi handia hartu du ehun-ingeniaritza arloaren barnean. Lan honen helburu nagusia da gai honi buruzko ikuspegi orokor bat ematea. Alde batetik, euskarriaren diseinuan polimero biodegradagarriaren hautapenak, mikroegiturak eta euskarriaren morfologiak duten garrantzia azaltzen da. Bestetik, atal honetan euskarriak lortzeko metodo ezberdinak ere deskribatzen dira. Bukatzeko, zelulen eta polimero-euskarriaren arteko elkarrekintzen ikerketak etorkizuneko medikuntza-aplikazioetarako duen garrantzia goraipatzen da

Mikrotxantiloien fabrikazioa eta hauen aplikazioak biomedikuntzan

Azken aldian, biobateragarriak diren eta zelulen itsaspen selektiboa baimentzen duten gainazalak biomedikuntzako zenbait aplikazio ezberdinetarako oso desiragarriak bihurtu dira. Bide horretatik, material biobateragarrietan horrelako gainazalak lortzeko, posible da mikrotxantiloiak (maila mikrometrikoan eginiko gainazaleko formak) erabiltzea; izan ere, horiek substratu zehatz baten gainean zelula-hazkunde kontrolatua eta bideratua baimendu ditzakete. Lan honetan, hain zuzen ere, mikrotxantilioak lortzeko teknikak berrikusten dira, hauek ehun-ingeniaritzan eta biomedikuntzan aurkitzen dituzten aplikazio nagusiak azpimarratuz, hala nola, biosentsoreak, ehun-ingeniaritzarako in vitro eginiko kultibo zelularrak eta inplante gainazal egokiak sortzea. Azkenik, zelulen itsaspen selektiboari dagokionez, gure ikerketa taldean 3D inpresioz sortutako mikrotxantiloi polimerikoen aurre-emaitzak aurkezten dira. Hala, emaitza horietatik ondorioztatu da 3D inpresioa teknika egokia dela mikrotxantiloi zehatzak, errepikakorrak eta egonkorrak fabrikatzeko.; The use of biocompatible surfaces that allow selective adhesion of cells has gained tremendous interest in the biomedical field. Micropatterns, defined as surface shapes at the micrometric scale, are introduced as a versatile approach to obtain such surfaces that can promote controlled and directed cell growth in a specific substrate. Here, state of the art techniques found in bibliography to obtain micropatterned surfaces are thoroughly reviewed, together with their main applications in the field of biomedicine and tissue engineering such as biosensors, cell cultures for tissue engineering and/or suitable implant surfaces. Finally, some preliminary results obtained in our research group are presented herein, which highlight the potential of 3D printing to achieve highly precise and accurate polymer micropatterns that promote selective cell adhesion

Radiopaque Material for 3D Printing Scaffolds

The so called “Additive manufacturing” is a new manufacturing process which consists in translating virtual solid model data into physical models in a quick and easy process. The most known example is 3D printing. In the present work, this novel technology will be used to print scaffolds with biomaterials. Due to the problems that arise when controlling the clinical course of an implant, graft or polymer inside the human body, an innovative idea has emerged: it consists in incorporating particles of barium sulfate in order to increase the radiopacity of the polylactide (PLLA) and thus making these materials visible to X-rays. Accordingly, BaSO4 loaded PLLA composites were prepared via melt-blending and then injected for further characterization by thermal transitions, mechanical properties, morphology and radiopacity. X-ray analyses confirmed the enhanced radiopacity of the BaSO4 filled composites in comparison to their unfilled counterparts. It is demonstrated that the loads not only contribute to the material's radiopacity, but also dramatically improve its ductility. As an illustration, the incorporation of 10 wt.% of BaSO4 particles resulted in an outstanding 1647% and 3338% increase in toughness and elongation of PLLA matrix, respectively. In view of the good properties of these materials, they will be used for 3D printing. Through this technique it can be molded with any shape in a matter of minutes, making the use of this technology appealing for further innovations.Authors are thankful for funds of Basque Government (GV/EJ) Department of Education (IT-927-16) and from MINECO (MAT 2016-78527-P). N. Sadaba is thankful for the predoctoral fellowship to POLYMAT Fundazioa- Basque Center for Macromolecular Design and Engineering