SbCl5—wet acetonitrile: a new system for chemoselective O-desilylation

Abstract—A new efficient method for deprotection of TBDMS derivatives of phenols, primary alcohols, carboxylic acids and secondary amines, consisting of SbCl5 and MeCN with 0.1% water (w/v), is reported. It effects inter alia desilylation of a CH2OTBDMS group in the presence of a ketal function

Small-scale field study of window films’ impact on daylight availability under clear sky conditions

Daylight illuminance levels and their spatial distribution are important design elements to achieve indoor visual comfort conditions and sustainability in buildings during the operation stage. While a proper daylighting scheme increases the efficiency of the building, the excessive use of glazed surfaces can contribute to thermal and visual discomfort, hence increasing the cooling demand and use of artificial lighting. Solar control film (SCF) is a self-adhesive thin film that can be applied on glazing systems of existing buildings for retrofitting purposes to modify thermal and optical properties of the glass substrate. This paper analyses experimentally the impact of single glazing with different SCFs on the indoor illuminance levels and respective distribution on horizontal work plane by comparing the measured absolute values and the useful daylight illuminance metric. Field experiments using a small scale model with the glazing oriented to the south, in Lisbon, were performed for a 6 mm clear glass and four different SCFs applied on the external surface of the glass, under clear sky conditions during summer and winter solstice at 9h00, 12h00, and 15h00. The results show that all SCFs reduced the indoor illuminance, which demonstrate their potential for glazing refurbishment when indoor visual discomfort occurs in buildings.FCT - Fundação para a Ciência e a Tecnologia (PD/BD/127848/2016

Synergistic effect of fibres on the physical, mechanical, and microstructural properties of aerogel-based thermal insulating renders

There is an increasing demand for highly efficient thermal insulating materials in buildings. This study presents a novel solution incorporating nanomaterials, such as silica aerogel, which can achieve low thermal conductivity values (below 0.030 W m-1 K-1) in renders. A key challenge of using aerogels is their low mechanical strength and high capillary water absorption. Here we describe a novel approach employing fibres which mitigates against some key properties which are decreased as a consequence of using aerogel. The incorporation of aramid (0.50%), sisal (0.10%), and biomass (0.10%) fibres (by total volume) was evaluated experimentally in terms of physical, mechanical, and microstructural properties. A synergistic effect between the fibres and aerogel increased mechanical resistance and a reduction in the capillary water absorption, when compared to the reference render (without fibres), whilst maintaining the low thermal conductivity. However, these properties depended significantly on whether the fibres were synthetic or organic. This study is important as it demonstrates that aerogel-based fibre-enhanced thermal renders can contribute to higher energy efficiency in both new construction and retrofitting. The use of these materials will have a direct positive impact on addressing the climate crisis

Synergistic effect of fibres on the physical, mechanical, and microstructural properties of aerogel-based thermal insulating renders

There is an increasing demand for highly efficient thermal insulating materials in buildings. This study presents a novel solution incorporating nanomaterials, such as silica aerogel, which can achieve low thermal conductivity values (below 0.030 W m-1 K-1) in renders. A key challenge of using aerogels is their low mechanical strength and high capillary water absorption. Here we describe a novel approach employing fibres which mitigates against some key properties which are decreased as a consequence of using aerogel. The incorporation of aramid (0.50%), sisal (0.10%), and biomass (0.10%) fibres (by total volume) was evaluated experimentally in terms of physical, mechanical, and microstructural properties. A synergistic effect between the fibres and aerogel increased mechanical resistance and a reduction in the capillary water absorption, when compared to the reference render (without fibres), whilst maintaining the low thermal conductivity. However, these properties depended significantly on whether the fibres were synthetic or organic. This study is important as it demonstrates that aerogel-based fibre-enhanced thermal renders can contribute to higher energy efficiency in both new construction and retrofitting. The use of these materials will have a direct positive impact on addressing the climate crisis

Studies in 3-oxy-assisted 3-aza Cope rearrangements

On thermolysis appropriately substituted N-silyloxy-N-allyl enamines undergo smooth 3,3-sigmatropic rearrangments to the corresponding N-silyloxy imino ethers

In-Situ Tests on Silica Aerogel-Based Rendering Walls

In this paper, two aerogel-based renders are characterized based on in-situ testing of walls prototypes. The in-situ tests to assess the mechanical performance are: pull-off, surface impact tests and compressive strength on collected samples. The physical performance includes the water resistance and thermal conductivity coefficient. The tests carried out to assess water-resistance are: Karsten tube, moisture meter and capillary water absorption of collected samples. The thermal performance was tested based on infrared thermography and thermal conductivity transient method. The combination of these in-situ tests allowed a better performance characterization of the aerogelbased renders and characterized the applied renders. These results were carried out under two national research projects (Nanorender and P2020 PEP)

Durability assessment of external thermal insulation composite systems in urban and maritime environments

External Thermal Insulation Composite Systems (ETICS) are multilayer solutions which provide an enhanced thermal performance to the building envelope. However, significant anomalies can be detected on ETICS facades, in some cases shortly after the application of these systems. This study intends to evaluate and compare the durability of six commercially available ETICS after two years of outdoor exposure at both urban and maritime conditions in Portugal. The systems were characterized by means of non-destructive testing (i.e., visual and microscopic assessment, water transport properties, thermal conductivity, surface roughness), thus allowing to evaluate the performance loss throughout natural aging. The bio-susceptibility and aesthetic properties (color and gloss) were also investigated. Results showed that the performance and durability of the complete system is significantly affected by the rendering system formulation. The lime-based specimens obtained the highest rate of mold development after one year of aging in a maritime environment, becoming considerably darker and with lower surface gloss. Fungal analysis of this darkish stained area indicated the presence of mold species of the genera Alternaria, Didymella, Cladosporium and Epicoccum, and yeasts of the genera Vishniacozyma and Cystobasidium. An increase of both capillary water absorption and water vapor permeability was also registered for the aged lime-based specimens. Acrylic-based systems obtained lower capillary water absorption after aging and greater dirt deposition on their surfaces, especially in urban conditions. These systems had also higher color variation and surface gloss decrease and slightly higher mold growth, when compared with those aged in a maritime environment. Finally, no mold growth was detected on the silicate-based specimens after two years of aging. However, these specimens obtained higher capillary water absorption and lower vapor permeability after aging, possibly leading to moisture accumulation within the system. Results contribute towards the development of ETICS with enhanced performance and durability.info:eu-repo/semantics/publishedVersio

Durability assessment of external thermal insulation composite systems in urban and maritime environments

Funding Information: The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the research project PTDC/ECI-EGC/30681/2017 (WGB_Shield – Shielding building facades for cities revitalization. Triple resistance to water, graffiti and biocolonization of external thermal insulation systems), the research units CERIS ( UIDB/04625/2020 ), CERENA ( UIDB/04028/2020 ) and iBB ( UIDP/04565/2020 ), the Associate Laboratory Institute for Health and Bioeconomy – i4HB ( LA/P/0140/2020 ), and the Ph.D. scholarship 2020.05180.BD (J. L. Parracha). The authors also acknowledge CIN, Saint-Gobain and Secil for the material supply and the Portuguese Institute for Sea and Atmosphere (IPMA) for the meteorological data. Funding Information: The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the research project PTDC/ECI-EGC/30681/2017 (WGB_Shield – Shielding building facades for cities revitalization. Triple resistance to water, graffiti and biocolonization of external thermal insulation systems), the research units CERIS (UIDB/04625/2020), CERENA (UIDB/04028/2020) and iBB (UIDP/04565/2020), the Associate Laboratory Institute for Health and Bioeconomy – i4HB (LA/P/0140/2020), and the Ph.D. scholarship 2020.05180.BD (J. L. Parracha). The authors also acknowledge CIN, Saint-Gobain and Secil for the material supply and the Portuguese Institute for Sea and Atmosphere (IPMA) for the meteorological data. Publisher Copyright: © 2022 Elsevier B.V.External Thermal Insulation Composite Systems (ETICS) are multilayer solutions which provide an enhanced thermal performance to the building envelope. However, significant anomalies can be detected on ETICS facades, in some cases shortly after the application of these systems. This study intends to evaluate and compare the durability of six commercially available ETICS after two years of outdoor exposure at both urban and maritime conditions in Portugal. The systems were characterized by means of non-destructive testing (i.e., visual and microscopic assessment, water transport properties, thermal conductivity, surface roughness), thus allowing to evaluate the performance loss throughout natural aging. The bio-susceptibility and aesthetic properties (color and gloss) were also investigated. Results showed that the performance and durability of the complete system is significantly affected by the rendering system formulation. The lime-based specimens obtained the highest rate of mold development after one year of aging in a maritime environment, becoming considerably darker and with lower surface gloss. Fungal analysis of this darkish stained area indicated the presence of mold species of the genera Alternaria, Didymella, Cladosporium and Epicoccum, and yeasts of the genera Vishniacozyma and Cystobasidium. An increase of both capillary water absorption and water vapor permeability was also registered for the aged lime-based specimens. Acrylic-based systems obtained lower capillary water absorption after aging and greater dirt deposition on their surfaces, especially in urban conditions. These systems had also higher color variation and surface gloss decrease and slightly higher mold growth, when compared with those aged in a maritime environment. Finally, no mold growth was detected on the silicate-based specimens after two years of aging. However, these specimens obtained higher capillary water absorption and lower vapor permeability after aging, possibly leading to moisture accumulation within the system. Results contribute towards the development of ETICS with enhanced performance and durability.publishersversionpublishe

A dramatic effect of double bond configuration in N-oxy-3-aza Cope rearrangements: a simple synthesis of functionalised allenes

The first examples of low temperature N-oxy-3-aza Cope rearrangements, leading to functionalised allenes are described, where the Z-configuration of the enaminic double bond in the rearranging system proves critical

Estudo das propriedades e biodegradabilidade de blendas de poliéster/amido submetidas ao ataque microbiano

This work deals with the biodegradation of blends of poly(beta-hydroxybutyrate)/starch and poly(beta-hydroxybutyrate-co-hydroxyvalerate)/starch. The blends were obtained by evaporation of the solvent in the mixture of the polymers in chloroform. Tests were carried out in presence of micro-organisms which acted as biodegradation agents. The blends were consumed as carbon substrate and the production of CO2 was evaluated in the process. In addition, the polyesters' mechanical properties were reduced by the incorporation of starch in its structure. (¹H) NMR and infrared spectroscopy detected some characteristic polyester degradation groups in the polyesters' chemical structure, thus confirming the alteration suffered by it