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Cork granules (Quercus suber L.) were slowly pyrolyzed at temperatures between 400-700 degrees C and under N-2 flow. While preserving its structure, some cells of the cork biochar became interconnected, allowing such carbon residue to be used as templates for manufacturing ceria redox materials. The pyrolytic char morphology was similar to that of the natural precursor. The produced cork biochar belonged to Class 1 (C > 60%) and possessed a high heating value of 32 MJ kg(-1). Other pyrolysis-derived compounds were identified and quantified through GC-FID and GC-MS analyses. The yield of gases released during cork pyrolysis was strongly dependent on the temperature used due to the thermal decomposition reactions involved in the degradation of cork. In particular, rising pyrolysis temperature from 500 to 700 T resulted in reducing the total hydrocarbon gases from 74 to 24 vol%. On the other hand, the yield of H-2 increased from 0 to 58% by increasing the pyrolysis temperature from 400 to 700 T. Due to the presence of suberin in cork, the composition and yield of bio-oil could be regulated by the pyrolysis temperature. Cork bio-oil was found to consist of long-chain hydrocarbons (from C11 to C24). The bio-oil resulting from the slow pyrolysis of cork residues is suitable as an appropriate feedstock for producing aliphatic-rich pyrolytic biofuels or as a source of olefms. Overall, the findings of this study suggest that Quercus suber L. could be a promising feedstock for biochar and biofuel production through the pyrolytic route and could contribute to the environmental and economic sustainability of the cork production industry. info:eu-repo/semantics/publishedVersion

DFA/BD/7882/2020 The pursuit of ever‐more efficient, reliable, and affordable solar cells has pushed the development of nano/micro‐technological solutions capable of boosting photovoltaic (PV) performance without significantly increasing costs. One of the most relevant solutions is based on light management via photonic wavelength‐sized structures, as these enable pronounced efficiency improvements by reducing reflection and by trapping the light inside the devices. Furthermore, optimized microstructured coatings allow self‐cleaning functionality via effective water repulsion, which reduces the accumulation of dust and particles that cause shading. Nevertheless, when it comes to market deployment, nano/micro‐patterning strategies can only find application in the PV industry if their integration does not require high additional costs or delays in high‐throughput solar cell manufacturing. As such, colloidal lithography (CL) is considered the preferential structuring method for PV, as it is an inexpensive and highly scalable soft‐patterning technique allowing nanoscopic precision over indefinitely large areas. Tuning specific parameters, such as the size of colloids, shape, monodispersity, and final arrangement, CL enables the production of various templates/masks for different purposes and applications. This review intends to compile several recent high‐profile works on this subject and how they can influence the future of solar electricity. publishersversion published

Developing solar technologies for converting H2O into H2 is a great challenge, as it leads to a sustainable alternative to the production of transportation fuels. The solar thermochemical approach seems particulary interesting since it uses high temperature process heat to drive a two-step cycle base on metal oxide redox reactions. N/A

Cerium oxide (CeO2), known as ceria, is widely used in several applications, such as automobile exhaust catalysts, electrolytes in solid oxide fuel cells, electrodes in gas sensors, and ultraviolet absorbents, owing to superior thermal and chemical stability, high ionic conductivity, good oxygen storage or release capacity and strong UV absorption. N/A

In the field of the liquid crystals in device applications, the polymer dispersed liquid crystal (PDLC) with permanent memory effect can become feasible in technological applications. Although studies of the liquid crystals in technological applications were extensively reviewed in the literature, not so much has been reported on the permanent memory effect (PME) in PDLCs. PDLCs can change transmittance from a totally opaque state to a totally transparent state during the application of an external electric field. Typically, the opaque appearance returns to the PDLC when the electric field is switched OFF. However, in this work PDLCs have been produced that use the electric field to create a highly transparent state but the transparent state remains even when the electric field is switched OFF giving rise to a permanent alignment state of LC molecules. This property is called a permanent memory effect (PME). For optimizing this effect a series of linear polyethylene glycol di(meth)acrylate and multi-arm polyethylene glycol with linear chains arms extending radially from a central core with reactive (meth)acrylate end groups were synthesized and characterized. The resulting pre-polymers and also some commercial ones were then tested in preparation of PDLCs. The 70 % of PME and the reproducibility even after multiple repetitions of the heating and electric field cycles application make the poly(ethyleneglycol) dimethacrylate of molecular weight 875 g mol-1 the most appropriate pre-polymer in preparation of PDLCs with PME. This effect is also dependent on the thermal polymerization which produces a polymer ball morphology type in the polymer matrix. In addition, PME is also highly dependent on the alignment layer type coating the glass PDLC cell (homogeneous alignment). With the high transparent state permanently displayed at room temperature through PME (70 %), an efficient procedure to allow the PDLC to acquire its opaque state has been achieved. A method of removing the PME has been outlined by Joule effect with the application of the electric current to the conductive layer (ITO) of the glass PDLC cell. This procedure makes the experimental setup to destroy the LC alignment structure simpler and more practical than by radiation heat. Conventional PDLCs need continuity of energy supply for keeping the ON state, which can be a very limiting aspect for many applications. However, PDLCs with PME besides having lower power consumption can be used in digital memory devices based on write-read-erase cycles. For this, a prototype has been assembled as proof of the concept to be used in the digital process of recording information with the binary language.

Dissertation to obtain the degree of master in Bioorganic Polymer dispersed liquid crystal (PDLC) films consist, commonly, on nematic liquid crystal domains dispersed in a polymeric matrix. These composites can be switched electrically from an opaque scattering state to a highly transparent state by an applied electric field. The molecular structure of the polymerisable monomers that can be incorporated as polymeric matrix plays an important role in the performance of PDLCs. Therefore, the aims of this work were to design and synthesise several new monomers that could be polymerised photochemically and thermally to be incorporated as polymeric matrices in PDLCs and investigate the influence of the molecular structure on the performance of these devices. Several monomers were synthesised in order to achieve better miscibility between the liquid crystal and the monomers during preparation of PDLC films. For this purpose, the monomers were synthesised so as to mimic some structural elements of the E7 liquid crystal molecules. Thus, several aromatic mono- and dimethacrylates with and without a linear chain spacer with five methylene units, as well as vinylic monomers were successfully synthesised. Mild and solvent freeprocedures were developed with reaction times as short as 1 to 5 min, using microwave irradiation. The structures of all isolated monomers were supported by 1H NMR, 13C NMR and FTIR spectroscopy, elemental analysis and melting point. Of all the synthesised monomers, the monomers that included in their structure aromatic rings bearing a cyano group and/or a linear chain spacer with five methylene units were fully characterised due to their higher molecular structure affinity with the E7 liquid crystal molecules. In order to evaluate the effect of these groups, these monomers were compared with those of similar structure but without the respective groups. Thus, DSC and POM with temperature ramps were used for the thermal characterisation of the monomers. The structural morphologies of the polymeric matrices were characterised by SEM. The monomers were also copolymerised with glycidyl methacrylate and the molecular weights of the resulting polymers were evaluated by GPC. The electro-optical properties of the PDLC films were determined by measuring the voltage dependence on the transmitted light. Fundação para a Ciência e Tecnologia - Project PTDC/CTM/69145/2006

New Polymer Networks for PDLC Films Application

We study the in vitro adsorption of fluoxetine hydrochloride by different adsorbents in simulated gastric and intestinal fluid, pH 1.2 and 7.5, respectively. The tested materials were two commercial activated carbons, carbomix and maxsorb MSC30, one activated carbon fibre produced in our laboratory and also three MCM-41 samples, also produced by us. Selected samples were modified by liquid phase oxidation and thermal treatment in order to change the surface chemistry without significant modifications to the porous characteristics. The fluoxetine adsorption follows the Langmuir model. The calculated Q0 values range from 54 to 1112 mg/g. A different adsorption mechanism was found for the adsorption of fluoxetine in activated carbon fibres and activated carbons. In the first case the most relevant factors are the molecular sieving effect and the dispersive interactions whereas in the activated carbons the mechanism seams to be based on the electrostatic interactions between the fluoxetine molecules and the charged carbon surface. Despite the different behaviours most of the materials tested have potential for treating potential fluoxetine intoxications.

Light management via photonic nanostructured coatings sustains a broad set of possible solar energy conversion enhancements, alternatively to conventional texturing processes that deteriorate solar cells (SCs) electrical transport through charge carrier recombination losses. These coatings, composed of high-refractive index materials structured at the sunlight wavelengths scale, can improve SCs efficiency, avoiding surface texturing processes while still allowing high-performance light trapping (LT). Here, through a highly scalable colloidal lithography methodology, proposed titanium dioxide (TiO2) nanovoid coatings were patterned on conventional (250 μm) and thin (90 μm) flat crystalline silicon (c-Si) wafers. These nanostructured coatings were also applied on textured (130 μm c-Si absorber), etched (140 μm) and flat (740 μm) c-Si interdigitated back contact solar cells (IBCSCs). The subsequent broadband absorption amplification was owing to the combined effects of (1) light scattering in near-infrared (NIR) wavelengths and (2) broad anti-reflection. With coated 250 μm c-Si wafers, a photocurrent density (𝐽𝑝ℎ) of 36.6 mA/cm2 was determined by absorption spectrum integration between 350 and 1200 nm. Approximately 84 % of the maximum theoretical 𝐽𝑝ℎ Lambertian LT limit is here attained with 669 and 693 nm of TiO2 thin photonic nanostructured coatings, respectively with the considered conventional and thin c-Si wafers. When integrated into test devices, outstanding optical improvements are attained without diminishing the original electrical performance by applying coatings with TiO2 thicknesses ≥ 545 nm. Unprecedent ~30 % of efficiency enhancement and 31.9 mA/cm2 of short-circuit current density (𝐽𝑠𝑐) are demonstrated with etched IBCSCs coated with 885 nm of TiO2 nanostructured coating. Additionally, unmatched optical angular acceptance is shown: 63 % of efficiency and 68 % of 𝐽𝑠𝑐 enhancements are respectively exhibited with 545 and 885 nm of TiO2 coatings for 80° of light incidence angle. Hence, with straightforward near-future integration in the established industry, a highly promising path for c-Si photovoltaic improvement is entailed. A gestão de luz mediante o uso de revestimentos nanoestruturados fotónicos sustenta um vasto leque de possíveis melhorias de conversão de energia solar, alternativamente a processos convencionais de texturização que deterioram o transporte eléctrico de células solares (CSs). Estes, compostos por materiais de elevado índice de refracção, podem elevar a eficiência de CSs, evitando texturizações enquanto possibilitam a captura de luz de elevado desempenho. Matrizes de nanocavidades de dióxido de titânio (TiO2) foram padronizadas por uma metodologia altamente escalável de litografia coloidal em bolachas de silício cristalino (c-Si) plano convencionais (250 μm) e finas (90 μm) e em CSs de contactos posteriores interdigitados (IBCSCs) texturizadas (130 μm c-Si), erodidas (140 μm) e planas (740 μm). A subsequente amplificação extensa da absorção deve-se à combinação dos seguintes efeitos: (1) dispersão de luz para comprimentos de onda do infravermelho próximo e (2) antirreflexão ampla. Com bolachas de c-Si convencionais, uma densidade de fotocorrente (𝐽𝑝ℎ) de 36.6 mA/cm2 determinada pela integração da absortância (350-1200 nm) foi conseguida. Aproximadamente 84 % do limite máximo teórico Lambertiano foi atingido com bolachas convencionais e finas revestidas com 792 e 693 nm de TiO2 nanoestruturado, respetivamente. Quando integrados em dispositivos de teste, a aplicação desses revestimentos com espessuras de TiO2 ≥ 545 nm conduziu a uma melhoria ótica substancial sem diminuir o desempenho elétrico original. Um aumento de ~30 % de eficiência e 31,9 mA/cm2 de densidade de corrente de curto-circuito (𝐽𝑠𝑐) são apresentados com IBCSCs revestidas com 885 nm de TiO2 nanoestruturado. É ainda demonstrada uma aceitação angular ótica incomparável: ganhos de 63 % de eficiência e 68 % de 𝐽𝑠𝑐, respetivamente com revestimentos de 545 e 885 nm de TiO2 nanoestruturado para um ângulo de luz incidente de 80°. Assim, com uma integração num futuro próximo na indústria, um caminho promissor para a evolução fotovoltaica em c-Si é implicado.