Experimental research on structural concrete masonry walls subjected to fire

The construction in masonry is one of the oldest ways of construction. However, the knowledge regarding its structural behavior is still not well consolidated, especially regarding extreme conditions, such as fire. Although the few available studies regarding structural masonry under fire conditions show some promising results, still the available normative documents seem to have some limitations regarding the topic, which highlights the need for further research, especially experimental, in this field. This paper presents the results of a study on the behavior of structural masonry walls subjected to simulated fire conditions. The specimens were built with three cells concrete blocks, which are common in European and US construction. In the fire resistance tests the walls were subjected to the action of a serviceability in-plane load and the ISO 834 fire curve. Temperatures were measured in the furnace, while temperatures and displacements were measured in the specimens. The obtained results were also compared with the Eurocode 6 part 1.2 predictions, for similar cases

New implementation of the Tau method for PDEs

AbstractIn this work we propose an extension of the algebraic formulation for the Tau method for the numerical solution of partial differential problems set on domains in Rn,n>2. This extension is based on an appropriate choice of a basis for the space of polynomials in Rn and on the construction of the algebraic equivalent representation of the problem. Another feature of this implementation is related to the solution procedure for the necessarily large dimensional linear systems involved. We developed for this purpose an adapted LU factorization with a special pivoting strategy to build approximants in the sense of Tau method and to allow the solution of large problems.Numerical results for differential problems in 2D and 2D will be shown

Numerical analysis on the behaviour of concrete masonry walls subjected to fire

This paper presents a numerical study on the structural behaviour of concrete masonry at elevated temperatures. Based on an experimental research previously performed on half-scale walls in fire situations, numerical models were developed and validated. The heat transfer models led to thermal fields with good agreement with the temperatures measured by thermocouples installed in the wall, a bigger scatter of temperatures was found in the experimental research. The mechanical analysis led to vertical and out-of-plane displacements in good agreement with the displacements measured by LVDTs. The numerical model was validated and will be used in future researches to perform parametric studies

Síndrome da Hiperemese por Canabinóides: O Diagnóstico Esquecido

Cannabis is the most cultivated and abused illicit drug worldwide. Paradoxically to the antiemetic properties attributed to cannabis, a relatively new cannabinoid hyperemesis syndrome (CHS) started to be recognized and is characterized by cyclic vomiting that are interspaced by asymptomatic phases. We present a case of a 36‑year‑old woman who repeatedly presented to the emergency room with cyclic vomiting that alleviated with hot showers. She was a long‑term cannabis user and the diagnosis was only established several years later after the onset of symptoms. The diagnostic work up was unremarkable, and the only effective treatment was cannabis cessation. Hot bathing behavior is a key characteristic of this syndrome. CHS is a new clinical condition that should be considered in a setting of recurrent and intractable vomiting in patients with a history of cannabis use.O canábis é a substância ilícita mais cultivada e consumida em todo o mundo. Paradoxalmente às propriedades antieméticas atribuídas ao canábis, a síndrome de hiperemese por canabinóides (SHC) começou a ser reconhecido e é caracterizado por episódios de vómitos cíclicos espaçados por períodos assintomáticos. Apresentamos o caso de uma mulher de 36 anos com múltiplos recursos ao serviço de urgência por vómitos persistentes que aliviavam com banhos quentes. Tinha história de consumos de canabinóides desde longa data e o diagnóstico de SHC só foi estabelecido após vários anos. O estudo complementar não revelou alterações e o único tratamento eficaz foi a cessação dos consumos. O recurso a banhos quentes é uma característica central deste quadro clínico. A SHC é uma entidade clínica que deve ser considerada em contexto de vómitos recorrentes difíceis de tratar em doentes com história de consumos de canábis

Machine learning for next-generation nanotechnology in healthcare

Funding: The authors acknowledge financial support from FCT Portugal in the framework of PhD grant 2020.06638.BD (to D.P.S.), and the European Research Council grant agreement 848325 (J. Conde for the ERC Starting Grant). T.R. is an Investigador Auxiliar supported by FCT Portugal (CEECIND/ 00684/2018).Nanotechnology for healthcare is coming of age, but automating the design of composite materials poses unique challenges. Although machine learning is supporting groundbreaking discoveries in materials science, new initiatives leveraging learned patterns are required to fully realize the promise of nanodelivery systems and accelerate development pipelines.publishersversionpublishe

In situ degradation of YSZ and YSZ + Al2O3 electrolytes of sensors used in glass melting furnaces

This work reports on the degradation of pure YSZ and YSZ +10 wt% alumina composite electrolytes by exposure to the atmosphere of a heat recovery chamber of an industrial glass furnace, at a temperature around 1300 °C. Microstructural observations and impedance spectroscopy measurements were used to evaluate the corrosion effects. YSZ samples directly placed in the sidewalls and intimately exposed to the dusts and volatiles in the atmosphere show strong corrosion effects after short periods. These samples present large amounts of a glassy phase in the intergranular region, containing the same elements as the common batch with inclusion of volatile species from the fuel. At the same time, the average composition of YSZ grains remains almost unchanged. Effects on the electrical properties are obviously stronger in the intergranular response, as confirmed by changes in the typical relaxation frequency. The protection of samples and/or their careful placement in the furnace strongly inhibit the corrosion process. The effectiveness of alumina addition to the YSZ electrolyte in increasing its corrosion resistance was only tested in protected samples, where the corrosion is less severe. For this reason, the expected benefits of this incorporation were found almost irrelevant

Normal and tangential behaviour of dry joints in refractory masonry

Industrial vessels used in high temperature processes of steel and cement production are protected by refractory linings built with mortarless joints. These dry joints, formed by stacked bricks have a crucial importance on the mechanical behaviour of the lining. The stiffness and consequently the stresses generated by thermal expansion are reduced due to the joints. The present article presents the results of experimental and numerical tests on the thermomechanical behaviour of these joints. The compressive strength of the brick was assessed at ambient and high temperatures and a statistical analysis of the distribution of the bricks’ shape imperfections was carried out. Several studies were carried out on the normal behaviour of the joints: classical joint closure test; bed joint closing action in a masonry wallet measured with a DIC; effects of brick’s height imperfections on its loadbearing capacity; effects of brick’s height imperfections on the wall’s behaviour at ambient and high temperatures and a comparison between the bed and head joints behaviour. To characterize the joint’s tangential behaviour at high temperatures a novel device was developed and presented.The authors would like to thank the support of European Commission under the framework of Marie Sklodowska-Curie Actions Innovative Training Networks, project ATHOR -Advanced THermomechanical multiscale mOdelling of Refractory linings 764987 Grant

Exploring chemical compound space with a graph-based recommender system

With the availability of extensive databases of inorganic materials, data-driven approaches leveraging machine learning have gained prominence in materials science research. In this study, we propose an innovative adaptation of data-driven concepts to the mapping and exploration of chemical compound space. Recommender systems, widely utilized for suggesting items to users, employ techniques such as collaborative filtering, which rely on bipartite graphs composed of users, items, and their interactions. Building upon the Open Quantum Materials Database (OQMD), we constructed a bipartite graph where elements from the periodic table and sites within crystal structures are treated as separate entities. The relationships between them, defined by the presence of ions at specific sites and weighted according to the thermodynamic stability of the respective compounds, allowed us to generate an embedding space that contains vector representations for each ion and each site. Through the correlation of ion-site occupancy with their respective distances within the embedding space, we explored new ion-site occupancies, facilitating the discovery of novel stable compounds. Moreover, the graph's embedding space enabled a comprehensive examination of chemical similarities among elements, and a detailed analysis of local geometries of sites. To demonstrate the effectiveness and robustness of our method, we conducted a historical evaluation using different versions of the OQMD and recommended new compounds with Kagome lattices, showcasing the applicability of our approach to practical materials design