Mechanical properties of duplex stainless steel laser joints

[EN] This work presents the influence of welding parameters on the microstructural parameters and mechanical behaviour of welded joints. In doing so, we seek to establish the microstructural changes in the molten area and the heat affected zone, which will define the mechanical properties of the welded joints. This mechanical behaviour is evaluated by means of traction tests on welded test pieces and microhardness scanning of the heat affected zone.The authors would like to express their gratitude to the Asociación de Investigación de Óptica de la Comunidad Valenciana [Community of Valencia Optics Research Association] for the application of the laser welds and to the Spanish Ministry of Science and Technology for its support through Project MAT2001-1123-C03-02.Amigó, V.; Bonache Bezares, V.; Teruel Biosca, L.; Vicente-Escuder, Á. (2006). Mechanical properties of duplex stainless steel laser joints. Welding International. 20(5):361-366. doi:10.1533/wint.2006.3582S36136620

Bone-Mimicking Injectable Gelatine/Hydroxyapatite Hydrogels

[EN] Bioactive synthetic hydrogels have emerged as promising materials because they can provide molecularly tailored biofunctions and adjustable mechanical properties. To mimic the mineralogical and organic components of the natural bone, hydroxyapatite and a tyramine conjugate of gelatine were combined in this study. The effect of various amounts of in situ synthesized hydroxyapatite in gelatine-tyramine on the morphology and physical properties of injectable hydrogels was investigated. Mineralogical identification confirmed successful precipitation of in situ formed hydrox yapatite. Better distribution of hydroxyapatite crystal agglomerates within modified gelatine was found at 5 % of hydroxyapatite, which could be responsible for increased storage modulus with respect to pure gelatine hydrogel. Prepared composite hydrogels are non-toxic and support the proliferation of Hek293 cells.The authors are grateful for the financial support of the Spanish Ministry of Economy and Competitiveness through the MAT2016-76039-C4-1-R project (including Feder funds) and the Croatian Science Foundation under the project IP-2014-09-3752.Rogina, A.; Sandrk, N.; Teruel Biosca, L.; Antunovic, M.; Ivankovic, M.; Gallego Ferrer, G. (2019). Bone-Mimicking Injectable Gelatine/Hydroxyapatite Hydrogels. Chemical and Biochemical Engineering Quarterly Journal. 33(3):325-335. https://doi.org/10.15255/CABEQ.2019.1663S32533533

Osteogenic differentiation of human mesenchymal stem cells on substituted calcium phosphate/chitosan composite scaffold

[EN] Ionic substitutions are a promising strategy to enhance the biological performance of calcium phosphates (CaP) and composite materials for bone tissue engineering applications. However, systematic studies have not been performed on multi-substituted organic/inorganic scaffolds. In this work, highly porous composite scaffolds based on CaPs substituted with Sr2+, Mg2+, Zn2+ and SeO3 2¿ ions, and chitosan have been prepared by freezegelation technique. The scaffolds have shown highly porous structure, with very well interconnected pores and homogeneously dispersed CaPs, and high stability during 28 days in the degradation medium. Osteogenic potential of human mesenchymal stem cells seeded on scaffolds has been determined by histological, immunohistochemical and RT-qPCR analysis of cultured cells in static and dynamic conditions. Results indicated that ionic substitutions have a beneficial effect on cells and tissues. The scaffolds with multi-substituted CaPs have shown increased expression of osteogenesis related markers and increased phosphate deposits, compared to the scaffolds with non-substituted CaPs.The financial supports of the European Regional Development Fund (grant KK.01.1.1.07.0014) , the PID2019-106000RB-C21/AEI/10.13039/501100011033 project from the Spanish Research Agency, and the L'Oreal-UNESCO "For Women in Science" Foundation are gratefully acknowledged.Ressler, A.; Antunovic, M.; Teruel Biosca, L.; Ferrer GG; Babic, S.; Urlic, I.; Ivankovic, M.... (2022). Osteogenic differentiation of human mesenchymal stem cells on substituted calcium phosphate/chitosan composite scaffold. Carbohydrate Polymers. 277:1-16. https://doi.org/10.1016/j.carbpol.2021.11888311627

Dye-sensitized solar cells made of titania nanoparticles structured into a mesoporous material

Using cetyltrimethylammonium bromide as the structure-directing agent, titania nanoparticles (3–5 nm) were organized into a mesoporous material (8.6 nm average pore size and 99 m2/g). The textural and spatial structuring of the mesoporous material were studied by hydrothermal gas adsorption, X-ray diffraction, and transmission electron microscopy. Dye-sensitized solar cells using mesoporous material exhibit a one order of magnitude increase in the overall efficiency with respect to analogous cells prepared using the same nanoparticles without periodic mesoporous material. This photovoltaic enhancement is due to increased adsorption of the dye (ruthenium polypyridyl N719) to the mesoporous material arising from the larger area of this mesoporous solid with respect to the same unstructured nanoparticles.Financial support by the Spanish DGI (CTQ2009-11586) is gratefully acknowledged. C. A. thanks the Spanish Ministry of Education for a Juan de la Cierva research associate contract.Aprile, C.; Teruel Biosca, L.; Alvaro Rodríguez, MM.; García Gómez, H. (2011). Dye-sensitized solar cells made of titania nanoparticles structured into a mesoporous material. Canadian Journal of Chemistry. 89(2):158-162. doi:10.1139/V10-122S158162892Grätzel, M. (2003). Dye-sensitized solar cells. Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 4(2), 145-153. doi:10.1016/s1389-5567(03)00026-1Grätzel, M. (1999). Mesoporous oxide junctions and nanostructured solar cells. Current Opinion in Colloid & Interface Science, 4(4), 314-321. doi:10.1016/s1359-0294(99)90013-4Kresge, C. T., Leonowicz, M. E., Roth, W. J., Vartuli, J. C., & Beck, J. S. (1992). Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism. Nature, 359(6397), 710-712. doi:10.1038/359710a0Corma, A. (1997). From Microporous to Mesoporous Molecular Sieve Materials and Their Use in Catalysis. Chemical Reviews, 97(6), 2373-2420. doi:10.1021/cr960406nSoler-Illia, G. J. de A. A., Sanchez, C., Lebeau, B., & Patarin, J. (2002). Chemical Strategies To Design Textured Materials:  from Microporous and Mesoporous Oxides to Nanonetworks and Hierarchical Structures. Chemical Reviews, 102(11), 4093-4138. doi:10.1021/cr0200062Ryoo, R., & Jun, S. (1997). Improvement of Hydrothermal Stability of MCM-41 Using Salt Effects during the Crystallization Process. The Journal of Physical Chemistry B, 101(3), 317-320. doi:10.1021/jp962500dYang, Q., Li, Y., Zhang, L., Yang, J., Liu, J., & Li, C. (2004). Hydrothermal Stability and Catalytic Activity of Aluminum-Containing Mesoporous Ethane−Silicas. The Journal of Physical Chemistry B, 108(23), 7934-7937. doi:10.1021/jp040124oKondo, J. N., & Domen, K. (2008). Crystallization of Mesoporous Metal Oxides†. Chemistry of Materials, 20(3), 835-847. doi:10.1021/cm702176mLlusar, M., & Sanchez, C. (2008). Inorganic and Hybrid Nanofibrous Materials Templated with Organogelators†. Chemistry of Materials, 20(3), 782-820. doi:10.1021/cm702141eTiemann, M. (2008). Repeated Templating†. Chemistry of Materials, 20(3), 961-971. doi:10.1021/cm702050sKartini, I., Menzies, D., Blake, D., da Costa, J. C. D., Meredith, P., Riches, J. D., & Lu, G. Q. (2004). Hydrothermal seeded synthesis of mesoporous titania for application in dye-sensitised solar cells (DSSCs). Journal of Materials Chemistry, 14(19), 2917. doi:10.1039/b406286hChoi, S. Y., Lee, B., Carew, D. B., Mamak, M., Peiris, F. C., Speakman, S., … Ozin, G. A. (2006). 3D Hexagonal (R-3m) Mesostructured Nanocrystalline Titania Thin Films: Synthesis and Characterization. Advanced Functional Materials, 16(13), 1731-1738. doi:10.1002/adfm.200500507Malfatti, L., Falcaro, P., Amenitsch, H., Caramori, S., Argazzi, R., Bignozzi, C. A., … Innocenzi, P. (2006). Mesostructured self-assembled titania films for photovoltaic applications. Microporous and Mesoporous Materials, 88(1-3), 304-311. doi:10.1016/j.micromeso.2005.09.027Ngamsinlapasathian, S., Pavasupree, S., Suzuki, Y., & Yoshikawa, S. (2006). Dye-sensitized solar cell made of mesoporous titania by surfactant-assisted templating method. Solar Energy Materials and Solar Cells, 90(18-19), 3187-3192. doi:10.1016/j.solmat.2006.06.021Zukalová, M., Zukal, A., Kavan, L., Nazeeruddin, M. K., Liska, P., & Grätzel, M. (2005). Organized Mesoporous TiO2Films Exhibiting Greatly Enhanced Performance in Dye-Sensitized Solar Cells. Nano Letters, 5(9), 1789-1792. doi:10.1021/nl051401lWang, H., Liu, Y., & Pinnavaia, T. J. (2006). Highly Acidic Mesostructured Aluminosilicates Assembled from Surfactant-Mediated Zeolite Hydrolysis Products. The Journal of Physical Chemistry B, 110(10), 4524-4526. doi:10.1021/jp056688pLee, J., Christopher Orilall, M., Warren, S. C., Kamperman, M., DiSalvo, F. J., & Wiesner, U. (2008). Direct access to thermally stable and highly crystalline mesoporous transition-metal oxides with uniform pores. Nature Materials, 7(3), 222-228. doi:10.1038/nmat2111Alvaro, M., Aprile, C., Benitez, M., Carbonell, E., & García, H. (2006). Photocatalytic Activity of Structured Mesoporous TiO2Materials. The Journal of Physical Chemistry B, 110(13), 6661-6665. doi:10.1021/jp0573240Alvaro, M., Aprile, C., Garcia, H., & Gómez-García, C. J. (2006). Synthesis of a Hydrothermally Stable, Periodic Mesoporous Material Containing Magnetite Nanoparticles, and the Preparation of Oriented Films. Advanced Functional Materials, 16(12), 1543-1548. doi:10.1002/adfm.200500766Aprile, C., Corma, A., & Garcia, H. (2008). Enhancement of the photocatalytic activity of TiO2through spatial structuring and particle size control: from subnanometric to submillimetric length scale. Phys. Chem. Chem. Phys., 10(6), 769-783. doi:10.1039/b712168gKim, Y. J., Lee, Y. H., Lee, M. H., Kim, H. J., Pan, J. H., Lim, G. I., … Lee, W. I. (2008). Formation of Efficient Dye-Sensitized Solar Cells by Introducing an Interfacial Layer of Long-Range Ordered Mesoporous TiO2Thin Film. Langmuir, 24(22), 13225-13230. doi:10.1021/la802340gLiu, Z., Li, Y., Zhao, Z., Cui, Y., Hara, K., & Miyauchi, M. (2010). Block copolymer templated nanoporous TiO2for quantum-dot-sensitized solar cells. J. Mater. Chem., 20(3), 492-497. doi:10.1039/b917634aNedelcu, M., Lee, J., Crossland, E. J. W., Warren, S. C., Orilall, M. C., Guldin, S., … Snaith, H. J. (2009). Block copolymer directed synthesis of mesoporous TiO2for dye-sensitized solar cells. Soft Matter, 5(1), 134-139. doi:10.1039/b815166kYoon, J.-H., Jang, S.-R., Vittal, R., Lee, J., & Kim, K.-J. (2006). TiO2 nanorods as additive to TiO2 film for improvement in the performance of dye-sensitized solar cells. Journal of Photochemistry and Photobiology A: Chemistry, 180(1-2), 184-188. doi:10.1016/j.jphotochem.2005.10.013Yue, W., Randorn, C., Attidekou, P. S., Su, Z., Irvine, J. T. S., & Zhou, W. (2009). Syntheses, Li Insertion, and Photoactivity of Mesoporous Crystalline TiO2. Advanced Functional Materials, 19(17), 2826-2833. doi:10.1002/adfm.200900658Yue, W., Xu, X., Irvine, J. T. S., Attidekou, P. S., Liu, C., He, H., … Zhou, W. (2009). Mesoporous Monocrystalline TiO2and Its Solid-State Electrochemical Properties. Chemistry of Materials, 21(12), 2540-2546. doi:10.1021/cm900197pNazeeruddin, M. K., Bessho, T., Cevey, L., Ito, S., Klein, C., De Angelis, F., … Graetzel, M. (2007). A high molar extinction coefficient charge transfer sensitizer and its application in dye-sensitized solar cell. Journal of Photochemistry and Photobiology A: Chemistry, 185(2-3), 331-337. doi:10.1016/j.jphotochem.2006.06.028Nazeeruddin, M. K., Splivallo, R., Liska, P., Comte, P., & Grätzel, M. (2003). A swift dye uptake procedure for dye sensitized solar cells. Chem. Commun., (12), 1456-1457. doi:10.1039/b302566gBrunauer, S., Emmett, P. H., & Teller, E. (1938). Adsorption of Gases in Multimolecular Layers. Journal of the American Chemical Society, 60(2), 309-319. doi:10.1021/ja01269a023Lee, W. J., Ramasamy, E., & Lee, D. Y. (2009). Effect of electrode geometry on the photovoltaic performance of dye-sensitized solar cells. Solar Energy Materials and Solar Cells, 93(8), 1448-1451. doi:10.1016/j.solmat.2009.03.00

Influence of Cation and Anion Type on the Formation of the Electroactive beta-Phase and Thermal and Dynamic Mechanical Properties of Poly(vinylidene fluoride)/Ionic Liquids Blends

[EN] Films based on poly(vinylidene fluoride) (PVDF) blended with ionic liquids (ILs) comprising different cations and anions were developed to investigate the IL influence on the resulting PVDF crystalline phase. Blends with 25 wt % IL content were produced by solvent casting followed by solvent evaporation at 210 degrees C in an air oven. Five different ILs containing the same cation 1-ethyl-3-methylimidazolium [Emim] and five ILs containing the same anion bis(trifluoromethylsulfonyl)imide [TFSI] were selected. The formation of the different phases and the resulting thermal and dynamic mechanical properties were studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. The incorporation of [Emim]-based ILs successfully directs the PVDF crystallization from the nonpolar alpha-phase toward the electroactive and highly polar beta-phase. On the contrary, blends containing [TFSI] as a common anion yield a mixture of alpha and beta phases. Overall, the induced beta-phase ranges between 14 and 95% depending on the incorporated IL type. Interestingly, 1-ethyl-3-methylimidazolium chloride [Emim] [Cl] is the most effective IL among the studied ones to significantly enhance the beta-phase content, showing also a marked nucleating effect. The results suggest that ions favorably interact with PVDF chains and are located occupying the amorphous interlamellar PVDF regions. Furthermore, the studied ILs act as plasticizers, yielding lower glass-transition temperatures of the amorphous phase and decreasing mechanical storage modulus at room temperature.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019. The authors thank FEDER funds through the COMPETE 2020 Programme and National Funds through FCT under the projects PTDC/BTM-MAT/28237/2017, PTDC/EEI-SII/5582/2014, and PTDC/FIS-MAC/28157/2017. D.M.C. and C.M.C. also acknowledge the FCT for grants SFRH/BPD/121526/2016 and SFRH/BPD/112547/2015, respectively. The financial supports from the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-(1 and 3)-R (AEI/FEDER, UE) (including the FEDER financial support) and from the Basque Government Industry and Education Departments under the ELKARTEK, HAZITEK, and PIBA (PIBA-2018-06) programs, respectively, are acknowledged. 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.Correia, D.; Costa, C.; Lizundia, E.; Sabater I Serra, R.; Gómez-Tejedor, J.; Teruel Biosca, L.; Meseguer Dueñas, JM.... (2019). Influence of Cation and Anion Type on the Formation of the Electroactive beta-Phase and Thermal and Dynamic Mechanical Properties of Poly(vinylidene fluoride)/Ionic Liquids Blends. The Journal of Physical Chemistry C. 123(45):27917-27926. https://doi.org/10.1021/acs.jpcc.9b07986S27917279261234

Crystallization monitoring of semicrystalline poly(vinylidene fluoride)/1-Ethyl-3-methylimidazolium hexafluorophosphate [Emim][PF6] ionic liquid blends

The electroactive characteristics of poly(vinylidene fluoride) (PVDF) are widely and increasingly being used in technological applications, where controlling the crystallization of the PVDF is of utmost importance. The nucleation and growth of crystals in the β or γ electroactive phases, or in the nonelectroactive α phase, depends on a number of factors that, despite the studies carried out, are still to be properly understood, in particular, when blended with specific active fillers. In this context, the crystallization of PVDF blended with the ionic liquid (IL) 1-ethyl-3-methylimidazolium hexafluorophosphate ([Emim][PF6]) has been analyzed. Both components are capable of crystallizing from the melt. The growth of the crystalline phases of PVDF during isothermal crystallization at different temperatures has been monitored using Fourier transform infrared (FTIR) spectroscopy. The isothermal crystallization kinetics of PVDF and the melting temperatures of both PVDF and IL were characterized by differential scanning calorimetry, and the microstructures of the blends were analyzed by optical and electron microscopy. It is observed for [Emim][PF6]/PVDF blends that the isothermal crystallization from the melt between 120 and 162 °C produces PVDF crystallites in the β and γ electroactive phases, while the formation of α-phase crystals is nearly suppressed. The morphology of the blends is altered by the addition of IL, which results in the separation of solid phases at room temperature. In addition, [Emim][PF6] remains liquid when mixed with the amorphous PVDF chains due to the cryoscopic descent.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019. The authors thank FEDER funds through the COMPETE 2020 Program and National Funds through FCT under the projects PTDC/BTM-MAT/28237/2017, PTDC/EEI-SII/5582/2014, and PTDC/FIS-MAC/28157/2017. D.M.C. thank the FCT for grant SFRH/BPD/121526/2016 and C.M.C. for the Investigator FCT Contract 2020.04028.CEECIND. The work of the Spanish groups has been funded by the Spanish State Research Agency (AEI) through the PID2019-106099RB-C41/AEI/10.13039/501100011033 project and from the Basque Government Industry and Education Departments under the ELKARTEK and PIBA (PIBA-2018-06) programs, respectively. 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

Emulsion based microencapsulation of proteins in poly(L-lactic acid) films and membranes for the controlled release of drugs

[EN] The aim of this study was to develop micro- or macro-porous substrates of poly(L-lactic acid) (PLLA) for the sustained release of water-soluble proteins. A model protein, bovine serum albumin (BSA), was incorporated into the hydrophobous PLLA matrix by emulsifying an aqueous BSA solution into an organic PLEA solution. The work focused on the effect of the fabrication procedure on substrates' microstructure and protein delivery kinetics. The films were prepared by solvent casting or freeze-extraction, after which the protein release profiles from both matrices were compared. A homogeneous distribution of BSA in the PLLA-films and membranes was obtained. In vitro release of the protein from the freeze extraction membranes was more significant than the release from the solvent cast films. BSA was found to be released from the freeze-extraction membranes in two stages: an initial fast release followed by a sustained release. The release from the solvent cast films was more moderated and accompanied by the polymer degradation.The authors are grateful for the financial support received from the Spanish Ministry through the 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 are financed by the "Instituto de Salud Carlos III" with assistance from the European Regional Development Fund. The authors' thanks are also due to the "Servicio de Microscopic Electronica" of the "Universitat Politecnica de Valencia" for their valuable assistance.Delmote, J.; Teruel-Biosca, L.; Gómez Ribelles, JL.; Gallego Ferrer, G. (2017). Emulsion based microencapsulation of proteins in poly(L-lactic acid) films and membranes for the controlled release of drugs. Polymer Degradation and Stability. 146:24-33. https://doi.org/10.1016/j.polymdegradstab.2017.09.012S243314