Assessment of the properties to characterize the interface between clay brick substrate and strengthening mortar

The behaviour of masonry elements under in-plane and out-of-plane loads can be improved through the application of strengthening systems based on reinforcing overlays. After strengthening, the transition region between the original substrate and the strengthening layer is especially stressed, and premature failure of the strengthened masonry is reached if insufficient interfacial capacity is assured. Therefore, the assessment of the mechanical behaviour of the interface is critical to the development of the masonry strengthening system based on the application of strengthening overlays. In this research a method for the characterization of the interface behaviour between two different materials, a polypropylene fibre reinforced mortar (PFRM) and a ceramic brick used for masonry construction is presented. Direct shear tests were carried out in couplet specimens. Due to the orthotropic nature of the bricks surface, the shear load was applied along three different directions in order to perform an overall estimation of the interface behaviour. The peak and residual shear stresses, as well as the failure modes, were obtained at different levels of the normal stress. Based on these experimental results constitutive laws were assessed for the simulation of the interface mechanical behaviour based on the Mohr and Mohr-Coulomb failure criteria.This research was carried in the framework of InoTec, Innovative material of ultra-high ductility for the rehabilitation of the built patrimony, funded by COMPETE/QREN/FEDER (NORTE-07-0202-FEDER-023024). InoTec project is promoted by CiviTest company and University of Minho. S&P Clever Reinforcement Ibérica is gratefully acknowledged for providing the materials used in the strengthening of the masonry specimen

Analysis of the interfacial debonding behaviour of NSM CFRP laminates with cement-based adhesive using Digital Image Correlation technique

The superb performance of carbon fiber reinforced polymer (CFRP) composites as near surface mounted (NSM) reinforcement in strengthening solutions for structures is already well recognized. Due to their deficiencies in fire conditions, cement-based adhesives as an alternative to polymeric matrices are recently suggested as a solution in these systems. However, the interface between the CFRP laminate and cement-based adhesives should have good stress transferring capacity. Thus, it is of great importance the research on improving this interface to increase the bonding capacity of CFRP/cement-based adhesive system. For that purpose, pull-out tests were conducted to examine the interfacial debonding process of two types of CFRP laminates: conventional smooth surface laminates and sand surface treated laminates. Digital image correlation (DIC) technique was used to verify the potentiality of the proposed sand treating approach. Therefore, the interlocking mechanism of sand treated laminates with the developed cement-based adhesive is assessed and the results are compared to those with non-treated smooth surface laminates. Furthermore, the bond-slip behaviour from pull-out tests is compared to obtained data through the DIC technique. The results verified the effectiveness of sand treatment approach applied to NSM CFRP reinforcements. Moreover, the DIC technique has revealed capable of providing qualitative and quantitative information in this regardFCT through the PTDC/ECMEST/1882/2014 FIRECOMPOSITE projec

Possibilidades e desafios do betão auto compactável reforçado com fibras : do laboratório à aplicação real

O estudo descrito neste artigo é parte integrante do programa de investigação “Prefabricated sandwich steel fiber reinforced panels” apoiado pelos FEDER e MCT, e promovido pela ADI (45% do montante solicitado). O terceiro e quarto autores agradecem as bolsas concedidas ao abrigo deste projecto de investigação. Este projecto envolveu as empresas PREGAIA e CIVITEST e a Universidade do Minho. Os autores gostariam de agradecer a cedência dos materias empregues, gentilmente cedidos pela degussa (superplastificante), SECIL (cimento), Bekaert (fibras) e Comital (filler calcárico). Agradece-se ainda a colaboração da Empresa FiberSensing pela colaboração prestada na monitorização do protótipo ensaiado na Prégaia.Neste trabalho resume-se a investigação desenvolvida no âmbito de um projecto de investigação aplicada, que tinha como objectivo essencial o de avaliar a possibilidade de conceber um painel em betão auto-compactável reforçado com fibras de aço (BACRFA) para painéis de fachada de edifícios, com vantagens técnicas e económicas quando se toma por base de comparação a solução em betão projectado reforçado com fibras de vidro. Para tal foi necessário desenvolver um método de concepção para o BACRFA. Posteriormente foi caracterizado o seu comportamento à compressão e à flexão, desde as 12 h aos 28 dias do BACRFA desenvolvido, e foi avaliado o desempenho do sistema estrutural proposto no que respeita ao seu comportamento à flexão e ao punçoamento. Para avaliar as dificuldades associadas à construção, em ambiente de pré-fabricação industrial, da solução proposta para o painel, foi construído um protótipo na empresa associada a este projecto. O desempenho estrutural do protótipo construído foi avaliado por intermédio de ensaio in situ

Painéis aligeirados em betão auto-compactável reforçado com fibras de aço

No presente artigo, é descrito um método de concepção para betão auto-compactável reforçado com fibras de aço (BACRFA) de custo competitivo, a ser usado na indústria de pré-fabricação. Uma das questões mais importantes na indústria da pré-fabricação é a da descofragem dos elementos, que deve ser feita com a maior brevidade possível. Deste modo, foi levado a cabo um programa experimental para estimar a influência da idade na resistência e na ductilidade do BACRFA desenvolvido. A relação tensão-abertura de fenda foi determinada com base na relação força-flecha obtida em ensaios realizados segundo as recomendações da RILEM (TC 162-TDF). Foi analisada a influência da idade do BACRFA nos parâmetros de fractura deste material. Foi analisada a influência da idade do BACRFA nos parâmetros de fractura deste material.A method to design cost competitive steel fiber reinforced self-compacting concrete (SFRSCC) for precasting industrial applications is described in this paper. Since demolding the elements as soon as possible is an important requirement in this industry, the influence of the age on the resistance and toughness of the designed SFRSCC was assessed carrying out an experimental program. Based on the force-deflection relationship obtained in the three point bending notched beam tests performed according to the RILEM TC 162-TDF recommendations, the stress-crack opening relationship of the SFRSCC was determined. The influence of the SFRSCC age on the fracture parameters of this material was analyzed

Terapia experimental da epilepsia com estimulação magnética transcraniana : ausência de melhora adicional com tratamento prolongado

Objetivo: investigar o efeito de três meses de estimulação magnética transcraniana repetitiva (EMTr) de baixa freqüência, na epilepsia de difícil controle. Método: Cinco pacientes (quatro homens, uma mulher, idades entre 6 e 50 anos), participaram do estudo; suas crises epilépticas não puderam ser controlados por tratamento medicamentoso e não tinham indicação cirúrgica; a EMTr foi realizada duas vezes por semana durante três meses, sendo que os pacientes anotaram o número diário de crises neste período, assim como nos três meses anteriores e posteriores ao tratamento. A aplicação da EMTr foi feita no vértex com bobina circular, com intensidade 5% abaixo do limiar motor. Durante as sessões de EMTr, 100 estímulos (5 séries de 20 estímulos, com um minuto de intervalo entre as séries) foram realizadas na freqüência de 0,3 Hz. Resultados: A média diária de crises (MDC) decresceu em três pacientes e aumentou em dois durante o uso da EMTr; um destes casos foi tratado somente por um mês; o melhor resultado foi encontrado em um paciente com displasia cortical focal (redução de 43,09% na MDC). Em todo o grupo de pacientes, houve decréscimo significativo na MDC de 22,8% (p<0,01). Conclusão: Embora o tratamento prolongado com a EMTr seja seguro e tenha sido registrado decréscimo moderado da MDC em um grupo de pacientes com epilepsia de difícil controle, respostas individuais de pacientes foram imprevisíveis e a relevância clínica deste método é provavelmente baixa. Nossos dados sugerem, contudo, que pacientes com lesões corticais focais podem ser beneficiar deste novo tipo de tratamento. Estudos futuros devem se concentrar neste grupo de pacientes.OBJECTIVE: To investigate the effect of three months of low-frequency repetitive transcranial magnetic stimulation (rTMS) treatment in intractable epilepsy. METHODS: Five patients (four males, one female; ages 6 to 50 years), were enrolled in the study; their epilepsy could not be controlled by medical treatment and surgery was not indicated. rTMS was performed twice a week for three months; patients kept records of seizure frequency for an equal period of time before, during, and after rTMS sessions. rTMS was delivered to the vertex with a round coil, at an intensity 5 % below motor threshold. During rTMS sessions, 100 stimuli (five series of 20 stimuli, with one-minute intervals between series) were delivered at a frequency of 0.3 Hz. RESULTS: Mean daily number of seizures (MDNS) decreased in three patients and increased in two during rTMS- one of these was treated for only one month; the best result was achieved in a patient with focal cortical dysplasia (reduction of 43.09 % in MDNS). In the whole patient group, there was a significant (p<0.01) decrease in MDNS of 22.8 %. CONCLUSION: Although prolonged rTMS treatment is safe and moderately decreases MDNS in a group of patients with intractable epilepsy, individual patient responses were mostly subtle and clinical relevance of this method is probably low. Our data suggest, however, that patients with focal cortical lesions may indeed benefit from this novel treatment. Further studies should concentrate on that patient subgroup

Novel bilayered Gellan gum/Gellan gum hydroxyapatite scaffolds for osteochondral tissue engineering applications

Osteoarthritis is a major cause of disability during aging. By the age of 60, close to 100% of the population will have histologic changes of degeneration in their knee cartilage (Loeser, 2000). Because of its avascular nature, cartilage has little capacity to self-regenerate. Despite the progress already achieved in osteochondral regeneration, some limitations have to be overcome. The formation of fibrocartilage has to be avoided and the innervation has to be improved. Further, one main feature to be promoted is the induction of vascularization in the bony part but not in the cartilage part and to avoid de-differentiation processes. A promising strategy could pass through the development and optimization of novel culture systems. The ideal approach could integrate scaffolds presenting regions with different physical characteristics, combined with different growth factors to support different stem cells fates, regarding the complex tissue physiology to be regenerate. This work aims to develop novel bilayered gellan gum (GG)/gellan gumhydroxyapatite (HAp) hydrogels based structures for osteochondral tissue engineering applications. Bilayered GG/GG-HAp hydrogels were produced by joining both solutions of GG 2% (w/v) with and without HAp (20% wt.) for bony and cartilage parts, respectively. The solutions were introduced into a silicone mould with 20:10 mm (height and diameter, respectively). Gelation of GG was promoted by immersion in PBS solution for 24 h. The architecture of the bilayered scaffolds was investigated by micro-computed tomography. Results have shown that the freeze-dried bilayered scaffolds composed by low acyl GG(2%(w/ v)/low acyl GG(2%(w/v)-HAp20%(w/w) possess a porosity of 83.4 ± 0.8%, pore size of 279.3 ± 38.6 lm and interconnectivity of 62.2 ± 5.4%. Degradability assays are being performed with the intent to use this system to culture human adipose derived stem cells inducing cell co-differentiation into chondrocytes and osteoblasts. Ultimately, the developed bilayered scaffolds will provide new therapeutic possibilities for the regeneration of osteochondral defects

Gellan gum-based hydrogel bilayered scaffolds for osteochondral tissue engineering

It has been shown that hydrogel bilayered scaffolds combining cartilage- and bone-like layers are most advantageous for treating osteochondral defects. In this study, it is proposed the use of low acyl gellan gum (LAGG) for developing bilayered hydrogel scaffolds for osteochondral tissue engineering. The cartilage-like layer of the GG-based bilayered hydrogel scaffolds is composed of LAGG (2 wt%). By adding a 2 wt% LAGG aqueous solution to different amounts of HAp (5-20 wt%) it was possible to produce the bone-like layer. In vitro bioactivity tests were performed by means of soaking the LAGG/LAGG-HAp hydrogel scaffolds in a simulated body fluid solution up to 14 days. Scanning electron microscopy, Fourier transform infra-red spectroscopy and X-ray diffraction analyses demonstrated that apatite formation is limited to the bone-like layer of the LAGG/LAGG-HAp bilayered hydrogel scaffolds

Ergonomics in "remote work" activities: a workstation adaptation case study in Brazil

The coronavirus disease 2019 (COVID-19) pandemic decreed by the outbreak of the new coronavirus culminated in the need to implement jobs in the homes of employees who had to adhere to the “remote work” style, due to social isolation actions in Brazil. Many of the employees started to work in the absence of adequate working conditions in their homes, impacting the three dimensions of ergonomics, i.e., physical, organizational and cognitive. The objective of this chapter is to report the adjustments made in a workplace after the change of modality from face-to-face (f2f) activities to “remote work” after the beginning of the pandemic in 2020, aiming to adopt actions aimed at ergonomics. The research was carried out with a professional in the area of Environmental and Sanitary Engineering who started remote work in March 2020. The work is of a qualitative nature, using photos to illustrate the changes occurring before and after the installation of the equipments and reports on strategies to improve working conditions in the “remote work”. The cost of physical adaptations was also computed. The most reported complaints collected by the professional were back pain, neck, forearm, wrist and eye pain, in addition to mental fatigue. The necessary equipment and furniture were acquired for the physical adaptation of the workspace. Issues of working hours, days off, means of communication were also addressed, but aspects of cognitive and organizational ergonomics must have the participation of the entire work group to achieve effective results. The accompaniment of a specialized technical professional would be important for the establishment of further assertive actions, seeking the productivity and quality of life of the employee.info:eu-repo/semantics/publishedVersio

Investigation of the Anticancer and Drug Combination Potential of Brominated Coelenteramines toward Breast and Prostate Cancer

Cancer is a very challenging disease to treat, both in terms of therapeutic efficiency and harmful side effects, which continues to motivate the pursuit for novel molecules with potential anticancer activity. Herein, we have designed, synthesized, and evaluated the cytotoxicity of different brominated coelenteramines, which are metabolic products and synthesis precursors of the chemi-/bioluminescent system of marine coelenterazine. The evaluation of the anticancer potential of these molecules was carried out for both prostate and breast cancer, while also exploring their potential for use in combination therapy. Our results provided further insight into the structure-activity relationship of this type of molecule, such as their high structural specificity, as well highlighting the 4-bromophenyl moiety as essential for the anticancer activity. The obtained data also indicated that, despite their similarity, the anticancer activity displayed by both brominated coelenteramines and coelenterazines should arise from independent mechanisms of action. Finally, one of the studied coelenteramines was able to improve the profile of a known chemotherapeutic agent, even at concentrations in which its anticancer activity was not relevant. Thus, our work showed the potential of different components of marine chemi-/bioluminescent systems as novel anticancer molecules, while providing useful information for future optimizations

PABERFIA : lightweight sandwhich panels in steel fiber reinforced self compacting concrete

Report 05-DEC/E-2