Probing the Molecular Ordering in Azopolymer Thin Films by Second-Order Nonlinear Optics

Second-harmonic generation (SHG), a second-order nonlinear optical technique, was used to investigate the molecular ordering of self-assembled layer-by-layer films of PAH, a cationic polyelectrolyte, and PS-119, an anionic polyelectrolyte containing photoisomerizable azo groups. Possible phase transitions in these multilayer films and their thermal stability were investigated by probing the SHG signal as a function of temperature and comparing the molecular order before and after thermal treatment. These studies were also performed with different pH values for the assembling solutions, a relevant parameter for polyelectrolyte adsorption. The results have shown that the films are not thermally stable, with the SHG signal nearly vanishing at a temperature of 150°C, in contrast to what is reported in the literature. SHG measurements have also confirmed that the films are isotropic in the plane of the samples, independent of their number of layers or the pH of assembling solutions. SHG signal before and after heating indicates that the SHG signal was considerably reduced at high temperatures, but after slow cooling it was recovered to almost the same value as before heating, showing that the thermal disorder is reversible. No phase transition was observed, since the SHG signal reduction was slow and gradual, without any sudden change that would characterize a glass transition. We demonstrate that the SHG technique provides information on the film arrangement at the microscopic level which could be difficult to get with traditional techniques

Ultrathin cellulose ester films: preparation, characterization and protein immobilization

In this study cellulose acetate butyrate (CAB) and carboxymehtylcellulose acetate butyrate (CMCAB) films adsorbed onto silicon wafers were characterized by means of ellipsometry, atomic force microscopy (AFM), sum frequency generation spectroscopy (SFG) and contact angle measurements. The adsorption behavior of lysozyme (LIS) or bovine serum albumin (BSA) onto CAB and CMCAB films was investigated. The amounts of adsorbed LIS or BSA onto CMCAB films were more pronounced than those onto CAB films due to the presence of carboxymethyl group in the CMCAB structure. Besides, the adsorption of BSA molecules on CMCAB films was more favored than that of LIS molecules. Antimicrobial effect of LIS bound to CAB or CMCAB layers was evaluated using Micrococcus luteus as substrate.FAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Squid – a simple bioinformatics grid

BACKGROUND: BLAST is a widely used genetic research tool for analysis of similarity between nucleotide and protein sequences. This paper presents a software application entitled "Squid" that makes use of grid technology. The current version, as an example, is configured for BLAST applications, but adaptation for other computing intensive repetitive tasks can be easily accomplished in the open source version. This enables the allocation of remote resources to perform distributed computing, making large BLAST queries viable without the need of high-end computers. RESULTS: Most distributed computing / grid solutions have complex installation procedures requiring a computer specialist, or have limitations regarding operating systems. Squid is a multi-platform, open-source program designed to "keep things simple" while offering high-end computing power for large scale applications. Squid also has an efficient fault tolerance and crash recovery system against data loss, being able to re-route jobs upon node failure and recover even if the master machine fails. Our results show that a Squid application, working with N nodes and proper network resources, can process BLAST queries almost N times faster than if working with only one computer. CONCLUSION: Squid offers high-end computing, even for the non-specialist, and is freely available at the project web site. Its open-source and binary Windows distributions contain detailed instructions and a "plug-n-play" instalation containing a pre-configured example

A two-step approach for the seismic assessment of masonry structures accounting for the actual masonry pattern

Seismic assessment of masonry structures is a pressing concern in the scientific community. Over the last few decades, significant progress has been made in developing numerical modelling strategies for masonry. However, due to the unique mechanics of masonry, which exhibit a quasi-brittle and anisotropic behaviour, there is no trade-off between accuracy and computational efficiency when conducting numerical simulations of masonry structures. This study proposes a new approach to conduct in-plane numerical simulations of masonry structures, which couple limit and pushover analyses considering the actual masonry pattern. The first step of the procedure involves a block-based limit analysis, which considers the actual masonry pattern. Macroblocks, i.e., the portions which compose the collapse mechanism, are then identified using an ad-hoc algorithm that searches for the pivot point of the obtained failure mechanisms. In the second step, a pushover analysis is conducted on the simplified structure composed of macroblocks, considered as continuum bodies, interacting via frictional interfaces. The proposed approach is preliminary tested on two structural-scale benchmarks made of dry-stack masonry, showing promising results.This research is partially funded by the School of Sustainability, Civil and Environmental Engineering, University of Surrey. This study is partly funded by the STAND4HERITAGE project (New Standards for Seismic Assessment of Built Cultural Heritage), which has received funding from the European Re search Council (ERC) under the European Union's Horizon 2020 research and innovation pro gram (Grant Agreement No. 833123) as an Advanced Grant. This work is also partly financed by MPP2030-FCT PhD Grants under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference PRT/BD/154348/2022. This project has received funding from the European Union's Horizon 2020 research and inno vation programme under the Marie Sklodowska-Curie grant agreement No 101029792 (HOLAHERIS project, "A holistic structural analysis method for cultural heritage structures conservation" https://site.unibo.it/holaheris/en)

Sistema de alvenaria com incorporação de resíduos: blocos de terra compactada com ligante geopolimérico

A produção de resíduos é um problema comum a todas as sociedades, que importa gerir de forma adequada para proteger o meio ambiente do impacto que atividade do Homem lhe provoca. O setor da construção civil é responsável por uma percentagem muito importante dos resíduos produzidos anualmente a nível Mundial. Como tal, exige-se que os agentes ligados a este setor desenvolvam soluções construtivas que promovam a valorização dos resíduos, com base na sua reciclagem em novos materiais de construção. Estes materiais, ao entrarem no mercado e ao serem integrados nas construções, permitiram substituir parte dos materiais correntes por materiais reciclados. Da execução de uma construção resultam resíduos compostos por diversas fileiras de materiais, de onde se destacam os solos resultantes de trabalhos de escavação, que podem ser reutilizados em trabalhos de aterro/enchimento necessários em obra, mas os solos excedentes constituem um problema a gerir. Estes solos podem ser reutilizados em outras obras ou transportados para uma bolsa de solos, onde aguardam reutilização. Contudo, os solos excedentes podem constitur um recurso que pode ser valorizado através da promoção de um uso alternativo em obra. No presente artigo pretende-se caracterizar o desempenho mecânico de um sistema de alvenaria à base de blocos de terra compactada (BTC). Estes BTC foram desenvolvidos com base na incorporação de solo residual granítico (SRG), típico do Norte de Portugal, estabilizado com um ligante geopolimérico. Este ligante é obtido por ativação alcalina de um outro resíduo, proveniente da indústria energética, nomeadamente as cinzas volantes. O desempenho do sistema de alvenaria de BTC foi avaliado através de um programa experimental, constatando-se um bom desempenho mecânico da solução.Este trabalho foi financiado por fundos do FEDER através do Programa Operacional Fatores de Competitividade – COMPETE e por fundos nacionais, através da Fundação para Ciência e a Tecnologia - FCT no âmbito do projeto POCI-01-0145-FEDER-007633 e da bolsa de pósdoutoramento FRH/BPD/97082/2013. Os autores agradecem ao Pedro Esteves o seu contributo na execução do programa experimental e ao Eng.º Jorge Henriques, em representação da PEGOP – Energia Elétrica SA, pela disponibilização da cinza volante

Experimental investigation on the repair of rammed earth by means of injection of mud grouts

This paper assesses the adhesion capacity of unmodified mud grouts used to repair structural cracks on medium and large scale rammed earth specimens. Beam and wallet-specimens were manufactured using a soil from Alentejo (Portugal), whose particle size distribution had to be first corrected due to its high clay content. An “artificial” (composed by kaolin and limestone powder) and a “natural” (composed by sieved soil and limestone powder) mud grout were used to repair the specimens, which were previously tested under three-point bending and diagonal-compression and then retested. The grout injection shown to provide satisfactory results regarding the adhesion capacity, but only if it is performed with the “natural” mud grout.Fundação para a Ciência e a Tecnologia (FCT

Polymer Solar Cells—Interfacial Processes Related to Performance Issues

Harnessing solar energy with solar cells based on organic materials (in particular polymeric solar cells) is an attractive alternative to silicon-based solar cells due to the advantages of lower weight, flexibility, lower manufacturing costs, easier integration with other products, low environmental impact during manufacturing and operations and short energy payback times. However, even with the latest efficiencies reported up to 17%, the reproducibility of these efficiencies is not up to par, with a significant variation in the efficiencies reported across the literature. Since these devices are based on ultrathin multilayer organic films, interfaces play a major role in their operation and performance. This review gives a concise account of the major interfacial issues that are responsible for influencing the device performance, with emphasis on their physical mechanisms. After an introduction to the basic principles of polymeric solar cells, it briefly discusses charge generation and recombination occurring at the donor-acceptor bulk heterojunction interface. It then discusses interfacial morphology for the active layer and how it affects the performance and stability of these devices. Next, the formation of injection and extraction barriers and their role in the device performance is discussed. Finally, it addresses the most common approaches to change these barriers for improving the solar cell efficiency, including the use of interface dipoles. These issues are interrelated to each other and give a clear and concise understanding of the problem of the underperformance due to interfacial phenomena occurring within the device. This review not only discusses some of the implemented approaches that have been adopted in order to address these problems, but also highlights interfacial issues that are yet to be fully understood in organic solar cells

Modelling the structural behaviour of rammed earth components

Proceedings of the Twelfth International Conference on Computational Structures Technology, B.H.V. Topping and P. Iványi, (Editors), Civil-Comp Press, Stirlingshire, Scotland.The rammed earth technique has a significant presence in the earthen built heritage, where was used to build from simple dwellings to fortresses. However, the high vulnerability of rammed earth construction to decay agents and to seismic events puts at risk their further existence and the lives of millions of people. With respect to the seismic behaviour of rammed earth walls, the understanding and modelling of their shear behaviour are topics rarely approached in literature. Nevertheless, these topics are of significant importance in the preservation and strengthening of rammed earth constructions. This paper presents experimental and numerical work where the shear behaviour of unstabilised rammed earth is analysed. The experimental program consisted in the testing of several unstabilised rammed earth wallets subject to diagonal compression, which allowed a better understanding of the shear behaviour of unstabilised rammed earth. The numerical work consists of the modelling, of the previous tests, using the finite element method and by considering both the macroand micro-modelling approaches. In general, the numerical models showed a good agreement with the experimental results.The authors would like to thank gratefully the funding provided by the Portuguese Science and Technology Foundation through project FCOMP-01-0124-FEDER-028864 (FCT-PTDC/ECM-EST/2396/2012). Furthermore, the authors wish to express their gratitude to Júlio Machado for his valuable help in the experimental program.info:eu-repo/semantics/publishedVersio

Shear behaviour characterization of dry-stack masonry made of compressed earth blocks

Como material de construção não normalizado, a terra é ainda associada à construção de subsistência dos países em desenvolvimento. Porém, as vantagens da construção em terra têm sido cada vez mais reconhecidas, nomeadamente a sua sustentabilidade. Esta mudança de paradigma tem levado ao desenvolvimento de técnicas modernas de construção em terra, particularmente a alvenaria de blocos de terra comprimida (BTC). A estabilização química tradicional do solo é um processo de melhoramento frequentemente utilizado, mas que também aumenta significativamente a energia incorporada dos BTC. Este artigo apresenta uma solução de estabilização alternativa para BTC, baseada na ativação alcalina de cinza volante. O comportamento mecânico dos BTC e da respetiva alvenaria de junta seca é estudado através de um programa experimental, que inclui a caraterização do comportamento ao corte da alvenaria.Raw earth, as a non-standard building material, is still associated to the poor construction from the developing countries. However, the advantages of earth construction have been increasingly recognized, namely its sustainability. This change of paradigm have been led to the development of modern earth construction techniques, in particular of the masonry made of compressed earth blocks (CEBs). The traditional chemical stabilization of the soil is an improvement process used frequently, but which increases significantly the embodied energy of the CEBs. This paper presents an alternative stabilisation technique for CEBs, based on the alkaline activation of fly ash. The mechanical behaviour of the CEBs and of the respective dry-stack masonry is investigated through an experimental program, which includes the characterization of the shear behaviour of the masonryFundação para a Ciência e a Tecnologia (FCT