Development of structural layers PVC incorporating phase change materials for thermal energy storage

The use of poly(vinyl chloride) (PVC) structural layers incorporating phase change materials (PCM) for latent heat thermal energy storage (LHTES) has become more attractive in the recent years compared to other supporting materials. In this study, PVC layers with different types of PCM were prepared using blending and compression moulding methods. Two types of synthesized PCM, one based on paraffin and calcium carbonate (PCM@CaCO3) and the other on paraffin, silica and graphene oxide (PCM@SiGO) have been developed to enhance the thermal conductivity of the PVC matrix and thus achieve a more effective charging and discharging process. PVC layers prepared using a commercial PCM (PCM@BASF) were also prepared for comparison. SEM images and DSC results reveal homogeneous distribution of the PCM in PVC layers and that most PCM particles are undamaged. The shell material (in the case of PCM@BASF) and the shape stability (in the case of synthesized PCM@CaCO3 and PCM@SiGO) prevent leakage of molten paraffin during the PVC layer production. The thermal conductivity profile of the PVC layer without PCM have a decreasing tendency with the temperature increase when determined using different measurement approaches, the transient plane heat source method (HotDisk Analyser, TPS 2500 S) and thermal flux meter method (steady-state method). However, for PVC layers with PCM the thermal conductivity profile shows a different behaviour when the mean surface temperature of the specimen is below the phase change transition temperature range (increasing tendency). During phase change transition (18–26 °C), the thermal conductivity presents two distinct tendencies. Firstly, the thermal conductivity reveals a decreasing tendency as the mean temperature of the specimen rises and afterwards an increasing tendency. Secondly, when the mean surface temperature is above the phase change transition temperature range, the thermal conductivity profile shows a decreasing tendency, independent of the PCM. The mechanical properties of PVC layers were also assessed and the results obtained revealed that the incorporation of PCM into the PVC matrix reduces the mechanical performance of the composites, however for LHETS applications not subjected to high tensile stress levels (over 1 kPa), this is not a significant drawback.publishe

Magnetic wood-based biomorphic Sr3Co2Fe24O41 Z-type hexaferrite ecoceramics made from cork templates

Ecoceramics (environmentally conscious ceramics) are biomimetic/biomorphic ceramics, which use a naturally occurring and sustainable material as a template for their unique morphology and structure. Usually woods (or lignocellulosics) are used, due to the inherent cellular nature of their microstructures. The wood is pyrolised and the resulting carbon skeleton impregnated with a fluid, and this is then heated to combust the carbon template and convert the fluid precursor into a ceramic, while maintaining the structure of the original natural template. For the first time, ecoceramics have been made from cork, a totally sustainable wood that is harvested without harming the tree. Also for the first time, ecoceramics have been made of soft magnetic Z-type hexaferrites, in this case the room temperature multiferroic strontium Z ferrite Sr3Co2Fe24O41 (SrZ). Cork powder was pyrolised at 1000°C, infiltrated with an aqueous sol-gel SrZ precursor, and then heated at 1200°C/2h to produce the ecoceramic. The cellular structure of the cork was maintained, with a small reduction in the hexagonal cell dimension to 10μm diameter, but the cell walls remained 1-2μm thick, of a similar magnitude to the hexaferrite grain size. Both magnetic and XRD data agreed that there was a small portion of the SrW phase present in these ecoceramics as well, and the magnetic loop showed a magnetically soft ecoceramic with Ms=59.5 A m2 kg -1 (at 3T), and a low Hc of 16 kA m-1

Accuracy of Siri and Brozek equations in the percent body fat estimation in older adults

To identify which equation, Siri or Brozek, based on the two compartment model, provides a more accurate conversion of body density (BD) in percent body fat (%BF) in a group of older adults. Cross-sectional study. Research Centre in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto. 60 older adults, aged 60-92 years. Skinfold thickness was used to estimate BD through Visser et al. prediction equation. The conversion of BD to %BF was done with Siri (%BF-Siri) and Brozek (%BF-Brozek) formulas and these determined values were both compared to Dual-Energy X-ray Absorptiometry (%BF-DXA) evaluations. A strong correlation between the %BF-DXA value and %BF-Siri (r=0.91, p < 0.001) and %BF-Brozek (r=0.91, p < 0.001) was found, although %BF-Siri and %BF-Brozek overestimated %BF-DXA (p < 0.001). The comparison of the %BF-Siri and %BF-Brozek mean values also revealed significant differences (p < 0.001). The %BF-Brozek reflects a better agreement than the %BF-Siri with %BF-DXA with respectively a mean difference of -4.0%BF (limits of agreement = -10.9 to 2.9%) and -5.7%BF (-12.6 to 1.2). The Bland and Altman plots confirmed that %BF-Brozek reflects a better agreement with %BF-DXA. The results of the present study show that the use of Brozek equation may correspond to a more accurate alternative than Siri equation for the conversion of BD in %BF in older adults

Development of an injectable PHBV microparticles-GG hydrogel hybrid system for regenerative medicine

Uncontrollable displacements that greatly affect the concentration of active agents at the target tissues are among a major limitation of the use of microparticulate drug delivery systems (DDS). Under this context a biphasic injectable DDS combining poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) microparticles (MPs) and a gellan gum (GG) injectable hydrogel is herein proposed for the localized delivery and long-term retention of MPs carrying hydrophilic and hydrophobic model active agents. A double emulsion-solvent evaporation method was adopted to develop the PHBV MPs, carrying bovine serum albumin (BSA) or dexamethasone (Dex) as hydrophilic and hydrophobic active agents’ models, respectively. Moreover, this method was modified, together with the properties of the hydrogel to tailor the delivery profile of the active agents. Variations of the composition of the organic phase during the process allowed tuning surface topography, particle size distribution and core porosity of the PHBV MPs and, thus, the in vitro release profile of Dex but not of BSA. Besides, after embedding hydrogels of higher GG concentration led to a slower and more sustained release of both active agents, independently of the processing conditions of the microparticulate system.The authors would like to acknowledge the Project RL1 - ABMR - NORTE-01-0124-FEDER-000016 co-financed by North Portugal Regional Operational Programme (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF). This work was partially supported by European Research Council grant agreement ERC-2012-ADG 20120216-321266 for project ComplexiTE

Coulomb and quantum oscillator problems in conical spaces with arbitrary dimensions

The Schr\"odinger equations for the Coulomb and the Harmonic oscillator potentials are solved in the cosmic-string conical space-time. The spherical harmonics with angular deficit are introduced. The algebraic construction of the harmonic oscillator eigenfunctions is performed through the introduction of non-local ladder operators. By exploiting the hidden symmetry of the two-dimensional harmonic oscillator the eigenvalues for the angular momentum operators in three dimensions are reproduced. A generalization for N-dimensions is performed for both Coulomb and harmonic oscillator problems in angular deficit space-times. It is thus established the connection among the states and energies of both problems in these topologically non-trivial space-times.Comment: 15 page

Molecular and functional characterization of a fads2 orthologue in the Amazonian teleost, Arapaima gigas

The Brazilian teleost Arapaima gigas is an iconic species of the Amazon. In recent years a significant effort has been put into the farming of arapaima to mitigate overfishing threats. However, little is known regarding the nutritional requirements of A. gigas in particular those for essential fatty acids including the long-chain polyunsaturated fatty acids (LC-PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The ability to biosynthesize LC-PUFA is dependent upon the gene repertoire of fatty acyl desaturases (Fads) and elongases (Elovl), as well as their fatty acid specificities. In the present study we characterized both molecularly and functionally an orthologue of the desaturase fatty acid desaturase 2 (fads2) from A. gigas. The isolated sequence displayed the typical desaturase features, a cytochrome b5-domain with the heme-binding motif, two transmembrane domains and three histidine-rich regions. Functional characterization of A. gigas fads2 showed that, similar to other teleosts, the A. gigas fads2 exhibited a predominant &Delta;6 activity complemented with some capacity for &Delta;8 desaturation. Given that A. gigas belongs to one of the oldest teleostei lineages, the Osteoglossomorpha, these findings offer a significant insight into the evolution LC-PUFA biosynthesis in teleosts

Prognostic significance of MUC2, CDX2 and SOX2 in stage II colorectal cancer patients

Background: Colorectal cancer (CRC) remains a serious health concern worldwide. Despite advances in diagnosis and treatment, about 15 to 30% of stage II CRC patients subjected to tumor resection with curative intent, develop disease relapse. Moreover, the therapeutic strategy adopted after surgery is not consensual for these patients. This supports the imperative need to find new prognostic and predictive biomarkers for stage II CRC. Methods: For this purpose, we used a one-hospital series of 227 stage II CRC patient samples to assess the biomarker potential of the immunohistochemical expression of MUC2 mucin and CDX2 and SOX2 transcription factors. The Kaplan-Meier method was used to generate disease-free survival curves that were compared using the log-rank test, in order to determine prognosis of cases with different expression of these proteins, different mismatch repair (MMR) status and administration or not of adjuvant chemotherapy. Results: In this stage II CRC series, none of the studied biomarkers showed prognostic value for patient outcome. However low expression of MUC2, in cases with high expression of CDX2, absence of SOX2 or MMR-proficiency, conferred a significantly worst prognosis. Moreover, cases with low expression of MUC2 showed a significantly clear benefit from treatment with adjuvant chemotherapy. Conclusion: In conclusion, we observe that patients with stage II CRC with low expression of MUC2 in the tumor respond better when treated with adjuvant chemotherapy. This observation supports that MUC2 is involved in resistance to fluorouracil-based adjuvant chemotherapy and might be a promising future predictive biomarker in stage II CRC patients.This work was supported by FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020 – Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT – Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Inovação in the framework of the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274) and projects POCI-01-0145-FEDER-029017 and POCI-01-0145-FEDER-016390. Diana Pádua acknowledges FCT for financial support through a PhD fellowship (SFRH/BD/146186/2019). The funding bodies played no role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript

3D-printed gelatin methacrylate scaffolds with controlled architecture and stiffness modulate the fibroblast phenotype towards dermal regeneration

Impaired skin wound healing due to severe injury often leads to dysfunctional scar tissue formation as a result of excessive and persistent myofibroblast activation, characterised by the increased expression of α-smooth muscle actin (αSMA) and extracellular matrix (ECM) proteins. Yet, despite extensive research on impaired wound healing and the advancement in tissue-engineered skin substitutes, scar formation remains a significant clinical challenge. This study aimed to first investigate the effect of methacrylate gelatin (GelMA) biomaterial stiffness on human dermal fibroblast behaviour in order to then design a range of 3D-printed GelMA scaffolds with tuneable structural and mechanical properties and understand whether the introduction of pores and porosity would support fibroblast activity, while inhibiting myofibroblast-related gene and protein expression. Results demonstrated that increasing GelMA stiffness promotes myofibroblast activation through increased fibrosis-related gene and protein expression. However, the introduction of a porous architecture by 3D printing facilitated healthy fibroblast activity, while inhibiting myofibroblast activation. A significant reduction was observed in the gene and protein production of αSMA and the expression of ECM-related proteins, including fibronectin I and collagen III, across the range of porous 3D-printed GelMA scaffolds. These results show that the 3D-printed GelMA scaffolds have the potential to improve dermal skin healing, whilst inhibiting fibrosis and scar formation, therefore potentially offering a new treatment for skin repair.The authors acknowledge funding from Science Foundation Ireland under the M-ERA.NET program, Transnational Call 2016 (17/US/3437; Ireland), EU BlueHuman Interreg Atlantic Area Project (grant EAPA_151/2016) and Science Foundation Ireland, through the Advanced Materials and BioEngineering Research Centre (AMBER; grants 12/RC/2278 and 12/RC/2278_P2)