Polymeric Shape-Memory Micro-Patterned Surface for Switching Wettability with Temperature

An innovative method to switch the wettability of a micropatterned polymeric surface by thermally induced shape memory effect is presented. For this purpose, first polycyclooctene (PCO) is crosslinked with dycumil peroxide (DCP) and its melting temperature, which corresponds with the switching transition temperature (Ttrans), is measured by Dynamic Mechanical Thermal Analysis (DMTA) in tension mode. Later, the shape memory behavior of the bulk material is analyzed under different experimental conditions employing a cyclic thermomechanical analysis (TMA). Finally, after creating shape memory micropillars by laser ablation of crosslinked thermo-active polycyclooctene (PCO), shape memory response and associated effect on water contact angle is analyzed. Thus, deformed micropillars cause lower contact angle on the surface from reduced roughness, but the original hydrophobicity is restored by thermally induced recovery of the original surface structureThe authors thank the Basque Country Government for financial support (Ayudas para apoyar las actividades de los grupos de investigacion del sistema universitario vasco, IT718-13). Technical and human support provided by SGIKER (UPV/EHU, MICINN, GV/EJ, ERDF and ESF) is gratefully acknowledged

Effects of Graphene Oxide and Chemically-Reduced Graphene Oxide on the Dynamic Mechanical Properties of Epoxy Amine Composites

Composites based on epoxy/graphene oxide (GO) and epoxy/reduced graphene oxide (rGO) were investigated for thermal-mechanical performance focusing on the effects of the chemical groups present on nanoadditive-enhanced surfaces. GO and rGO obtained in the present study have been characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD) demonstrating that materials with different oxidation degrees have been obtained. Thereafter, GO/epoxy and rGO/epoxy nanocomposites were successfully prepared and thoroughly characterized by dynamic mechanical thermal analysis (DMTA) and transmission electron microscopy (TEM). A significant increase in the glass transition temperature was found in comparison with the neat epoxy. The presence of functional groups on the graphene surface leads to chemical interactions between these functional groups on GO and rGO surfaces with the epoxy, contributing to the possible formation of covalent bonds between GO and rGO with the matrix. The presence of oxidation groups on GO also contributes to an improved exfoliation, intercalation, and distribution of the GO sheets in the composites with respect to the rGO based composites.Authors would like to acknowledge the Basque Government funding within the ELKARTEK 2015-2016 (KK-2015/00094) and 2016-2017 (KK-2016/00097) Programme, "ACTIMAT", ETORGAI 2014, Graphnology (ER-2014/00014) and Ayudas para apoyar las actividades de los grupos de investigacion del sistema universitario vasco (IT718-13)

Reversible First-Order Single Crystal to Single Crystal Thermal Phase Transition in [(CH3)3CNH3]4[V4O12]

[EN] The well-known compound tetrakis(tert-butylammonium)-cyclo-tetrametavanadate (V), [(CH3)3CNH3]4[V4O12] (1h_RT), which crystallizes in the tetragonal I4/m space group, undergoes an irreversible solid state transformation upon heating, constituting one of the few examples in which the initial and the final stages are structurally characterized by sc-XRD. Now, we observed the ability of the same compound to undergo an additional single-crystal-to-single-crystal (SCSC) transformation upon thermal stimuli, but this time at low temperatures (153 K). Compound 1h_RT contains a discrete unprotonated [V4O12]4− tetrahedral anion in which V and O bridging atoms are coplanar. In both phases, these tetrameric anions are linked through tert-butylammonium cations in an extensive network of hydrogen bonds, but at low temperatures, this phase loses its characteristic O-V-O coplanarity, with the resulting rearrangement of the crystal packing and hydrogen-bond network which provide its reversibility at low temperatures. Again, the initial and final stages have been characterized structurally by sc-XRD.This research was funded by IT1722-22, KK-2022/00045 and MCIN, grant MAT2017-89553-P

Towards a new generation of non-cytotoxic shape memory thermoplastic polyurethanes for biomedical applications

In recent decades, the technology of polymeric materials used in biomedical applications has been greatly improved, replacing the metals that had been used until now. This change has not only meant an improvement in the cost of the raw material and in its processing, but it is also due to the fact that there are applications, such as stents, where the material is required to have a certain flexibility, both during the surgical intervention and during the healing or conditioning the tissue in which the intervention is performed. In this type of application, the so-called shape memory polymers (SMPs) are very interesting, but for this, they must meet the condition of being biocompatible. In this work, new polyurethane materials have been designed in which, in addition to shape memory prevailing, adequate cell proliferation values are obtained for possible use in biomedical applications. Furthermore, during the synthesis, in order to avoid undesired and toxics subproducts, instead of the typical aromatic diisocyanates, an aliphatic 1,6-hexamethylene diisocyanate (HDI) has been selected. Moreover, neither solvents nor catalysts were used, which makes eco-friendly synthesis suitable for scaling at an industrial level. Finally, castor oil (CO) has been used as one of the main synthesis reagents, which is an abundant compound obtained from biological sources. For all this, it can be concluded that the polymers described here have a wide range of application possibilities (biomedicine, food packaging…), and are highly interesting to preserve our Planet.Authors would like to acknowledge the Basque Government funding within the ELKARTEK 2020 AVANSITE (KK-2020/00019). Also, authors gratefully acknowledge funding from the University of the Basque Country (GIU20/075). The authors thank for technical and human support provided by SGIker (UPV/EHU/ ERDF, EU)

Understanding informal jewellery apprenticeship in Ghana: Nature, processes and challanges

Context: The processes of acquiring education in jewellery in Ghana has been dominated by the informal apprenticeship system and it forms the backbone of the workforce of the jewellery industry in Ghana. However, the patronage of informal jewellery apprenticeship in Ghana in recent times has been on decline even though it has the potential of training human resources to transform Ghana’s precious mineral resources sector.This is based on the belief that jewellery trade and its training are shrouded in secrecy, in other words, the jewellery trade is considered to be a sacred profession where information on its operating systems are not allowed to be shared easily. It is believed to be associated with cult and magic, hence the reluctant to admit people who are from outside the family of particular jewellery enterprise. This study is sought to bring to fore the understanding nature, processes and challenges of the informal jewellery apprenticeship in Ghana. Approach: The study adopted the descriptive and phenomenology research designs (qualitative research methods). Jewellers who own a jewellery business and who are training other people through apprenticeships as well as people who are trained are observed and interviewed. A sample size was selected through purposive and convenience sampling techniques from four jewellery enterprises in Accra, Ghana. A thematic analysis plan was adopted to generate fndings of the study. Findings: The results show that for a person to train as a jeweller, s/he has to enrol by going through induction, futhremore fees (money and perishable items) are to be paid. The training content is driven by orders received by the master jeweller, thereby making it unstructured and lacking criteria for assessing the performance and progress of apprentice jewellers. Teaching and learning methods are usually on-the-job training that rely on demonstrations and observation. Conclusion: Informal jewellery apprenticeship in Ghana uses a fexible, cost-efective approach for transferring jewellery making skills from masters to apprentice jewellers, and it has substantial potential for improving skills training in the country. Sometimes the reluctant of some jeweller to train others is to keep the trade to family members only

Analysis of the influence of microencapsulated phase change materials on the behavior of a new generation of thermo-regulating shape memory polyurethane fibers

The present work is a first approach in order to achieve thermo-sensitive and waterproof polyurethane fibers useful in the textile industry. For this, two polyurethane formulations with glass transition temperatures (Tg) close to the body temperature have been synthetized and characterized by several techniques such as Ther-mogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic-Mechanical Analysis (DMA) and Thermo-mechanical analysis (TMA). In this manner their thermal and shape memory behavior were determined. It was also estimated the water vapor transmission rate of both polyurethane films. Then, integration of two different microencapsulated phase change materials (PCMs), one with organic shell and another one, with an inorganic shell, was carried out by extrusion in order to achieve materials with thermo-regulating properties. Fibers for both polyurethanes, pristine or loaded with microencapsulated PCMs, were again characterized to check that the thermal and shape memory properties are maintained, and to study their capability to storage and release energy. The promising results pave the way for a new generation of thermo-regulating materials useful in numerous applications such as the textile sector.Authors would like to acknowledge the Basque Government funding within the ELKARTEK 2019 (KK-2019/00039) and ELKARTEK 2021 (KK-2021/00040) and FRONTIERS IV Prog rammes

On The Multiscale Structure and Morphology of PVDF-HFP@MOF Membranes in The Scope of Water Remediation Applications

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is a highly versatile polymer used for water remediation due to its chemical robustness and processability. By incorporating metal-organic frameworks (MOFs) into PVDF-HFP membranes, the material can gain metal-adsorption properties. It is well known that the effectiveness of these composites removing heavy metals depends on the MOF's chemical encoding and the extent of encapsulation within the polymer. In this study, it is examined how the micro to nanoscale structure of PVDF-HFP@MOF membranes influences their adsorption performance for CrVI. To this end, the micro- and nanostructure of PVDF-HFP@MOF membranes are thoroughly studied by a set of complementary techniques. In particular, small-angle X-ray and neutron scattering allow to precisely describe the nanostructure of the polymer-MOF complex systems, while scanning microscopy and mercury porosimetry give a clear insight into the macro and mesoporosity of the system. By correlating nanoscale structural features with the adsorption capacity of the MOF nanoparticles, different degrees of full encapsulation-based on the PVDF-HFP processing and structuration from the macro to nanometer scale are observed. Additionally, the in situ functionalization of MOF nanoparticles with cysteine is investigated to enhance their adsorption toward HgII. This functionalization enhanced the adsorption capacity of the MOFs from 8 to 30 mg·g−1.The authors thank financial support from the Spanish Agencia Estatal de Investigación (AEI) through Tailing43Green-ERAMIN project. This study forms part of the Advanced Materials program and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by The Basque Government under the IKUR program. Basque Government Industry and Education Departments under the ELKARTEK and PIBA (PIBA-2022-1-0032) programs, are also acknowledged. Ainara Valverde thanks the Basque Government (Education Department) for her PhD grant (PREB_2018_1_004). The MSCA-RISE-2017 (No 778412) INDESMOF actions that received funding from the European Union's Horizon 2020 research and innovation programme is also acknowledged. The authors acknowledge as well the CERIC-ERIC Consortium for the access to experimental SANS&SAXS facilities and financial support. The authors would like to acknowledge the use of the Somapp Lab, a core facility supported by the Austrian Federal Ministry of Education, Science and Research, the Graz University of Technology, the University of Graz, and Anton Paar GmbH. This work was supported as well by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project UIDB/04650/2020 and project PTDC/FIS-MAC/28157/2017. P.M.M. thanks the FCT for contract 2020.02802.CEECIND. The authors thank the technical and human support provided by SGIker (UPV/EHU)

Desiccation Tolerance in Chlorophyllous Fern Spores: Are Ecophysiological Features Related to Environmental Conditions?

Fern spores of most species are desiccation tolerant (DT) and, in some cases, are photosynthetic at maturation, the so-called chlorophyllous spores (CS). The lifespan of CS in the dry state is very variable among species. The physiological, biochemical, and biophysical mechanisms underpinning this variability remain understudied and their interpretation from an ecophysiological approach virtually unexplored. In this study, we aimed at fulfilling this gap by assessing photochemical, hydric, and biophysical properties of CS from three temperate species with contrasting biological strategies and longevity in the dry state: Equisetum telmateia (spore maturation and release in spring, ultrashort lifespan), Osmunda regalis (spore maturation and release in summer, medium lifespan), Matteuccia struthiopteris (spore maturation and release in winter, medium-long lifespan). After subjection of CS to controlled drying treatments, results showed that the three species displayed different extents of DT. CS of E. telmateia rapidly lost viability after desiccation, while the other two withstood several dehydration-rehydration cycles without compromising viability. The extent of DT was in concordance with water availability in the sporulation season of each species. CS of O. regalis and M. struthiopteris carried out the characteristic quenching of chlorophyll fluorescence, widely displayed by other DT cryptogams during drying, and had higher tocopherol and proline contents. The turgor loss point of CS is also related to the extent of DT and to the sporulation season: lowest values were found in CS of M. struthiopteris and O. regalis. The hydrophobicity of spores in these two species was higher and probably related to the prevention of water absorption under unfavorable conditions. Molecular mobility, estimated by dynamic mechanical thermal analysis, confirmed an unstable glassy state in the spores of E. telmateia, directly related to the low DT, while the DT species entered in a stable glassy state when dried. Overall, our data revealed a DT syndrome related to the season of sporulation that was characterized by higher photoprotective potential, specific hydric properties, and lower molecular mobility in the dry state. Being unicellular haploid structures, CS represent not only a challenge for germplasm preservation (e.g., as these spores are prone to photooxidation) but also an excellent opportunity for studying mechanisms of DT in photosynthetic cells.This work was funded by (i) the Basque Government (research project UPV/EHU IT-1018-16, UPV/EHU IT-718-13, and Predoctoral Fellowship to MLP); (ii) Royal Botanic Gardens Kew receives grant-in-aid from Defra. Spanish Ministry of Science, Innovation and Universities (MCIU/FEDER, UE) (PGC2018-093824-B-C44). Eusko Jaurlaritza (Award number(s): UPV/EHUIT-1018-16); Eusko Jaurlaritza (Award number(s): UPV/EHUIT-718-13); Department for Environment, Food and Rural Affairs (Award number(s): Royal Botanic Gardens Kew receives grant-in-aid from Defra); Eusko Jaurlaritza (Award number(s): Predoctoral Fellowship to MLP); Spanish Ministry of Science, Innovation and Universities (MCIU/FEDER, EU) (PGC2018-093824-B-C44)

First evidence of freezing tolerance in a resurrection plant: insights into molecular mobility and zeaxanthin synthesis in the dark

The photoprotective mechanisms of desiccation tolerance and freezing toler- ance and their relation to molecular mobility (cell vitrification) were assessed in a single model: the exceptional subalpine and resurrection plant Ramonda myconi. Dehydrated leaves showed a drop in maximal photochemical effi- ciency of PSII (Fv/Fm) accompanied by synthesis of zeaxanthin (Z), even in the dark, which was limited by cell vitrification after complete desiccation. The recovery of Fv/Fm after a severe drying treatment (7 days at 50% rela- tive humidity) confirmed the tolerance of R. myconi leaves to desiccation. In winter, R. myconi plants showed a highly dynamic component of pho- toinhibition. Interestingly, the potential activity of the enzyme violaxanthin de-epoxidase (VDE) occurred at −7∘C, below the freezing temperature range of the leaves (−2 ± 2∘C) and even in the dark. This suggests that, in nature, the enzyme can still be active in frozen leaves, as long as they are above the glass transition temperature. The drop in Fv/Fm and increase in Z were reversible upon rehydration and thawing, respectively, but were not perfectly matched, suggesting that both Z-independent and Z-dependent forms of sustained dissi- pation are occurring. Overall, our data reinforce the light-independent activity of the VDE enzyme under stress and suggest that Z-accumulation could occur in darkness in a scenario when temperatures drop dramatically in the night under natural conditionsFinancial support from Basque Government (UPV/EHU IT-1018-16 and UPV/EHU IT-718-13); Spanish Ministry of Economy and Competitiveness (MINECO) and the ERDF (FEDER) (CTM2014 – 53902-C2 – 2-P) to J.G.-P., A.V. and B.F.-M.; “Juan de la Cierva-Incorporation” postdoctoral fellowship IJCI-2014-22489 to B. F-M.; and Univer- sity of St. Thomas Sabbatical Assistance Grant to A. V. are acknowledge