New Generation of High Efficient OLED Using Thermally Activated Delayed Fluorescent Materials

The search for efficient materials for organic light emitting diodes is one of the most imperative research area. The focus is to obtain a bright large area emitter, limited by the low internal quantum efficiency of conventional organic emitters. Recently, a new generation of the organic materials (TADF) with a theoretical internal quantum efficiency up to 100%, opened new frameworks. However, significant challenges persist to achieve full understanding of the TADF mechanism and to improve the OLEDs stability. Starting from the photo-physical analysis, we show the relationship with the molecular electrical carrier dynamics and internal quantum efficiencies. The OLED structure, fabrication, and characterization are also discussed. Several examples for the full color emitters are given. Special emphasis on experimental results is made, showing the major milestones already achieved in this field

Experimental evaluation of the potential use of waste recycled concrete fine aggregates to produce self-compacting concrete

The current concern with sustainability in the construction sector has led to the adoption of processes to minimise the impact on the environment. The use of recycled concrete aggregates in self-compacting concrete (SCC), as an alternative to natural aggregates, seems to be a solution with great potential. However, it is common knowledge that the use of recycled aggregates in the production of SCC instead of natural aggregates may causes changes in some of its properties, both in the fresh and hardened state, and that the magnitude of those changes will depend on the percentages of incorporation and the nature of recycled aggregates. When using the mix design methodology proposed by Nepomuceno et al, SCC is assumed to be consisted basically of two phases, namely, the liquid phase (mortar phase) and the solid phase (coarse aggregates), being the main SCC properties controlled by the mortar phase. In this perspective, this research work reports the results obtained when testing mortars with flow properties appropriate to produce SCC, when binary and ternary blends of powder materials were used and natural fine aggregates were partially replaced by recycled concrete fine aggregates. The experimental program carried out involved, in a first stage, the production and testing of 11 binary mortar mixtures suitable for the production of SCC, with replacement percentages of natural fine aggregate by recycled concrete fine aggregate varying from 0% (reference mixture) to 50%, in 5% increments. Subsequently, 6 ternary mortar mixtures were produced and tested for the same purpose, with replacement percentages of natural fine aggregate by recycled concrete fine aggregate varying from 0% (reference mixture) to 50%, in 10% increments. Binary mortars included Portland cement type I 42.5R and limestone powder, while ternary mortars included Portland cement type I 42.5R, limestone powder and fly ash. In both cases, the dosages of superplasticizer and mixing water were determined experimentally to obtain the required fresh properties suitable to produce SCC. The results indicate that the 28 days age compressive strength and density of the mortars decrease with the increase in the percentage of incorporation of recycled concrete fine aggregates, regardless of whether they are mortars with binary or ternary blends of powders. In binary mixtures, the mixing water dosage increases with the percentage of incorporation of recycled aggregates, while in ternary mixtures the opposite occurs, at least up to a percentage of 40% of incorporation of recycled aggregates. The superplasticizer dosages, necessary to obtain the appropriate flow properties, were always higher in the ternary mixtures compared to the binary mixtures, even comparing only the reference mixtures. It can be concluded that mortars with the incorporation of recycled concrete fine aggregates constitute a viable material with potential for use in the construction industry, provided that the necessary adjustments to its performance are considered, thus contributing to the sustainability of construction.info:eu-repo/semantics/publishedVersio

The thermomechanical behaviour of high alumina bricks

The modelling, design and optimisation of refractory masonry structures and refractory linings requires the understanding of its thermomechanical properties. The most used techniques for thermomechanical characterization of refractory ceramics is presented in this communication, as well the most important properties used for designing. This study is focused on the work lining of steel ladles, the masonry studied is composed by high alumina bricks with dry joints. The mechanical behaviour of alumina spinel bricks is been investigated by compressive strain-stress curves at different temperatures. The characterization of refractory masonry is required for calibration and validation of numerical models and for definitions of nonlinear homogenization techniques. The first step is the mechanical characterization of the bricks. Compressive tests are being performed at cylindrical samples extracted from the bricks to generate its compressive strain-stress curves at room temperature, 600ºC, 800ºC and 1.000ºC. The samples dimension is 50 mm in diameter by 130 mm in height. An electric split furnace will be used to heat the samples at the rate of 5ºC/min. The strains will be measured using a strain gage positioned at the opening of the furnace and the displacement given by the press will monitored. A 200 kN press with an electromechanical jack will be used to apply the compressive load. The results of the brick characterization tests are the compressive strain-stress curves of the material. It will be possible to identify the compressive strength of the material at room temperature (fc) and the compressive strength at a given temperature Θ (fc,Θ). The strain corresponding to fc (ec1) and the rupture strain (ecu) may also be determined for each temperature. The compressive strain-stress curves may be used for modelling, once they represent the damage plasticity of the material. This research will generate experimental results that will be used for calibration and validation of numerical models. Once the models are validated, they will be used to optimise the design of refractory masonry used at steel ladles

The characterization of joint behaviour in mortarless refractory masonry

The understanding of the compressive and tangential behaviour of mortarless joints is mandatory to optimize the design of refractory linings. The joints play an important role during the heating of the equipment, as they reduce the stresses generated due to thermal expansion. This study investigates the normal and tangential behaviour of joints in alumina spinel bricks. The mechanical characterization of the compressive strength of the material is performed at room and elevated temperature. During fabrication this brick, it is pressed, therefore, tests were performed in pressing and orthogonal-to-pressing direction. The thickness of joints is estimated based on a compressive test in two stacked bricks, the joint closure is an nonlinear and strongly heterogeneous and nonlinear phenomena. The determination of the friction angle and friction coefficient of the bricks were performed based on a slipping test.European Commission, Marie Skłodowska-Curie Actions Innovative Training Networks in the frame of the project ATHOR - Advanced THermomechanical multiscale modelling of Refractory linings 764987 Gran

Numerical simulations on refractory lining for steel casting vessels

The manufacturing of several materials adopted in industry, civil construction and our daily life has processes performed at high temperatures, such as melting and heat treatments. Thus, these production processes require products that resist to high temperatures, maintaining their physical and chemical properties in service. Refractory ceramics, due to their properties, have been used for this purpose, having crucial importance in high temperature processes. Refractory linings (composed of refractory ceramics) are used in industrial vessels to produce steel, iron, cement, non-ferrous metals, glass, metallic alloys, in melting process, in petrochemical industry, in incinerators, in mineral processing, in power plants and many other applications. This paper presents the results of a large numerical simulations used to represent the thermomechanical behaviour of steel vessels. Different modelling techniques were used and the results detailed and discussed

Critérios para definição da composição de betões leves autocompactáveis com agregados de argila expandida

[PT] Este artigo resume um estudo experimental que teve como objetivo definir parâmetros para a composição de betões leves autocompactáveis (BAL), incorporando agregados grossos de argila expandida e agregados finos de areia natural. Partindo da metodologia proposta por Nepomuceno et al. para os betões autocompactáveis de densidade normal (BAC), investigaram-se as alterações necessárias para produzir os BAL. Avaliou-se a curva granulométrica de referência dos agregados grossos leves e as propriedades do escoamento das argamassas adequadas à produção dos BAL. Avaliou-se a segregação estática e investigou-se a relação entre os parâmetros da mistura, a trabalhabilidade, a resistência à compressão e a massa volúmica seca. Concluiu-se que a absorção dos agregados leves constitui um aspeto relevante e que a curva de referência dos agregados grossos, bem como as propriedades reológicas das argamassas propostas por Nepomuceno et al. para os BAC, são adequadas à obtenção de BAL. Concluiu-se que a composição terá de resultar do equilíbrio entre a resistência à compressão e a massa volúmica seca pretendidas, uma vez que a resistência à compressão depende da razão água/cimento e do volume de agregados leves e este último afeta a massa volúmica seca.Nepomuceno, M.; Pereira-De-Oliveira, L.; Pereira, S. (2018). Critérios para definição da composição de betões leves autocompactáveis com agregados de argila expandida. En HAC 2018. V Congreso Iberoamericano de hormigón autocompactable y hormigones especiales. Editorial Universitat Politècnica de València. 127-136. https://doi.org/10.4995/HAC2018.2018.5352OCS12713

Patient-Centered Medicine and Self-Care of Patients with Type 2 Diabetes: A Cross-Sectional Study

Introduction: Even though the prevalence rate of diabetes in Portugal is one of the highest in Europe, no studies on the association between patient centered medicine, diabetes self-care, and glycemic control have been published. Assuming that patient centered medicine increases adherence to treatment through the improvement of the doctor-patient relationship, the aim of this study was to assess the influence of patient-centered medicine on the self-care of patients with type 2 diabetes patients’ (T2DM) in two Family Health Units in Central Portugal, according to gender and age. Material and Methods: A cross-sectional study was conducted in two Family Health Units in Central Portugal between the 25th November 2021 and the 15th January 2022. Patients with type 2 diabetes were invited to fill in the Patient-Centered Medicine questionnaire, for patients (PCM-p) (where higher values represent worse results) and the Summary of Diabetes Self-Care Activities Measure (SDSCAM), (where higher values represent better results), while healthcare professionals filled in the epidemiologic variables on pre-defined days. Results: A sample of 298 patients with type 2 diabetes was studied. Linear regressions for the association between SDSCAM scale factors and PCM-p showed significant associations for general diet (β = -0.07, p < 0.001), specific diet (β = -0.10, p < 0.001), exercise (β = -0.03, p = 0.008), foot care (β = -0.11, p < 0.001) and medication adherence in general (β = -0.06, p = 0.001). Multiple linear regression including the association between glycated hemoglobin (HbA1c) and the SDSCAM scale dimensions showed that specific diet was associated with lower HbA1c levels (β = -0.01, p = 0.007) and blood sugar testing (β = 0.01, p < 0.001) and that a higher score in PCMp was associated with higher HbA1c levels (β = 0.06, p < 0.001). Male patients (β = -6.93, p = 0.007) and older patients (β = -0.42, p = 0.001) were associated with lower scores in the specific diet. The male gender was associated with higher scores in exercise (β = 7.62, p = 0.029), lower scores in foot care (β = -6.06, p = 0.029) and lower scores in medication adherence to injectable medicines/6.2 (β = -0.73, p = 0.018). Age was associated with a lower score in medication (β = -0.03, p = 0.045) and a higher PCMp total score (β = 0.07, p = 0.030). Conclusion: Patient-centered medicine in type 2 diabetics is associated with better self-care behaviors in patients with type 2 diabetes. Gender and age differences were observed in self-care behaviors and age differences were observed in Patient Centered Medicine

Glass waste powder addition used as mitigator of concrete alkali-silica reaction

The recycled aggregates from demolition of concrete structures affected by alkali silica reaction as well as the potentially reactive natural aggregates are often a matter of great concern and fear in case of new structures construction. Thus, to encourage the recycling and use of some potential reactive aggregates under scientific basis, this paper presents an experimental study where suspected alkali-silica reactive recycled aggregates was used. The main goal of this study is evaluate the influence of waste glass powder addition as mitigator of the concrete expansive reaction. In a first phase, the level of expansibility of different aggregates was identified using accelerated tests in mortars bars, method ASTM C1260 and an adapted accelerated test on specimens of 40 x 40 x 160 mm. In a second phase, tests were performed on concrete mixtures, according to CMBT method, with 100% recycled reactive coarse aggregates and powder addition, such as the glass powder and metakaolin. The powder additions percentages were incorporated at 20%, 40% and 60% of cement weight. The results of mortars bars test showed opposite results according to the method applied, i.e. , the same aggregates considered as harmless by the adapted method are considered reactive by the ASTM method, if the same expansion limit of 0,10% for 16 days was adopted for both methods. Finally, the concrete results obtained with CMBT method showed that glass powder and metakaolin had a significant mitigation effect in alkali-aggregate reaction development

Rheological behaviour of cement mortars reinforced with acrylic fibres

The fibre reinforcement efficacy of mortar is dependent upon many factors, including the properties of the matrix as well as the fibre geometry, size, type, volume and dispersion. Among the plastic fibres typically used in mortars, little or nothing is known about the rheological behaviour of acrylic fibres. Thus, in this study the influence of different acrylic fibres characteristics on the rheological behaviour of cement mortars was investigated. The method selected is based on factorial design of experiments in which the parameters considered are the length, diameter and acrylic fibre content. The test results indicate that Herschel-Bulkley model better simulate the rheological behaviour of acrylic fibres reinforced mortars. It was also observed that the yield stress increases with the reduction of fibre length and diameter and the plastic viscosity increases as the fibre length increases.info:eu-repo/semantics/publishedVersio

Consultation hold: interruptions during General Practice consultations

Introduction: The impact of interruptions (IR) in consultations is recognized. A study in Ireland identified IR in 53 of 212 consultations (25%) and the most common source was the phone. In Spain, 91% and 54% of consultations of two family doctors had an IR, with a mean duration of 35 and 16 seconds. Objective: To characterize the IR in consultations of the researchers’ Health Unit, in the centre of Portugal. Methods: Cross-sectional study. Authorization granted by Official Ethics Committee. General and Family Medicine consultations periods with at least 2 hours were randomized, by doctor in 2 weeks of evaluation. Informed consent was signed by patients. The researcher physician sat in the corner of the consulting room and recorded the information in a specifically designed data sheet. Significant IR was defined as the one lasting more than 5 seconds and/or changing the flow of the consultation. Inside and outside IR was defined according to origin in relation to consulting room. Data were analyzed by descriptive and nonparametric inferential statistics. Results: 37 of 63 consultations (58.7%) had at least one IR, with a mean duration of 42 seconds. No significant difference comparing weeks (p=0.440) or morning/afternoon periods (p=0.556). 19 consultations had 1 IR (51.4%), followed by 2 IR (10), 3 IR (6), 4 and 5 IR (1). In 34 consultations (91.9%) the IR were considered significant and in 30 consultations (83.3%) were considered unjustified. Of 66 IR, 57 (86.4%) were significant. The commonest source was the door [29 (43.9%) of the total and 27 (47.4%) of the significant IR], mainly caused by a physician [specialist (24%) and intern (21%)], followed by patient (21%), nurse (17%) and technical assistant (17%). Other sources were patient or doctor’s phone mobile (18.2%), lack of material (12.1%), consulting room telephone (10.6%), electronic problem (7.6%) and exit from office (7.6%). Lack of material and 3 cases of exit from office were considered justified. Outside factors had greater impact on consultations (p=0.041). Discussion: In this study at least half of the consultations had an IR. The door stands out as the main source and had a high impact. The IR by an intern may represent peculiarities of the formation. The inside factors, mainly the phone mobile and exit from office, are related to core doctor/patient and revealed to have a lesser impact. Correction measures can improve performance for even the justified IR can be avoided