Interest in dendrimer-based nanomedicines has been growing recently, as it is possible to precisely manipulate the molecular weight, chemical composition, and surface functionality of dendrimers, ...tuning their properties according to the desired biomedical application. However, one important concern about dendrimer-based therapeutics remainsthe nondegradability under physiological conditions of the most commonly used dendrimers. Therefore, biodegradable dendrimers represent an attractive class of nanomaterials, since they present advantages over conventional nondegradable dendrimers regarding the release of the loaded molecules and the prevention of bioaccumulation of synthetic materials and subsequent cytotoxicity. Here, we present an overview of the state-of-the-art of the design of biodegradable dendritic structures, with particular focus on the hurdles regarding the use of these as vectors of drugs and nucleic acids, as well as macromolecular contrast agents.
Understanding the risks associated with the likelihood of extreme events and their respective consequences for the stability of hydraulic infrastructures is essential for flood forecasting and ...engineering design purposes. Accordingly, a hydrological methodology for providing reliable estimates of extreme discharge flows approaching hydraulic infrastructures was developed. It is composed of a preliminary assessment of missing data, quality and reliability for statistically assessing the frequency of flood flows, allied to parametric and non-parametric methods. Model and parameter uncertainties are accounted for by the introduced and proposed modified model averaging (modified MM) approach in the extreme hydrological event's prediction. An assessment of the parametric methods accuracy was performed by using the non-parametric Kernel Density Estimate (KDE) as a benchmark model. For demonstration and validity purposes, this methodology was applied to estimate the design floods approaching the case study 'new Hintze Ribeiro bridge', located in the Douro river, one of the three main rivers in Portugal, and having one of Europe's largest river flood flows. Given the obtained results, the modified MM is considered a better estimation method.
•Three-step risk-based methodology for bridge foundations scour evaluation.•Hydrological modeling incorporates model uncertainty by using an aver-aging approach.•Main flow characteristics are ...simulated with the open-source HEC-RAS model.•Bridge scour assessment takes advantage of HEC-RAS scour module.•Methodology can be potentially incorporated into regular bridge inspection schedules.
The collapse of bridges inevitably leads to economical losses and may also be responsible for human fatalities. A bridge may fail due to several reasons, with local scouring around its foundation being the most common. Despite decades of scouring research, there are still many uncertainties affecting the design process of bridge piers. The most critical and least explored are the hydrological and hydraulic variables. The recent intensification of floods may also increase the vulnerability of bridges to scour effects. Therefore, the present work aims to propose a risk-based methodology for considering scour at bridge foundations. It is composed of three main steps: (i) assessing extreme hydrological events (hazards); (ii) modeling river behavior through the computation of flow characteristics and bridge scour depths; and (iii) assessing bridge scour risk by associating its scour depth to foundation depth ratio with the priority factor (vulnerability) and assigning a qualitative evaluation of the scour risk rating (level of risk). The hydrological modeling incorporates uncertainty with an averaging approach in the design floods definition. The flow characteristics are simulated with the HEC-RAS model, which also contains a scour module for bridge scour assessment. However, other empirical estimates are considered for simple and pile-supported foundations. This study ends with a qualitative assessment of how the scouring phenomenon affects bridge vulnerability and its safety. The proposed risk-based methodology - validated through a case study, the new Hintze Ribeiro bridge in Portugal - can be potentially incorporated into regular bridge inspection schedules as a useful tool for risk management measures, assisting in catastrophic events’ prevention.
The complex trajectories of higher education students are deviations from the regular path due to delays in completing a degree, dropping out, taking breaks, or changing programmes. In this study, we ...investigated degree changing as a cause of complex student trajectories. We characterised cohorts of students who graduated with a complex trajectory and identified the characteristics that influenced the time to graduation. To support this predictive task, we employed machine learning techniques such as neural networks, support vector machines, and random forests. In addition, we used interpretable techniques such as decision trees to derive managerial insights that could prove useful to decision-makers. We validated the proposed methodology taking the University of Porto (Portugal) as case study. The results show that the time to degree (TTD) of students with and without complex trajectories was different. Moreover, the proposed models effectively predicted TTD, outperforming two benchmark models. The random forest model proved to be the best predictor. Finally, this study shows that the factors that best predict TTD are the median TTD and the admission regime of the programme of destination of transfer students, followed by the admission average of the previous programme. By identifying students who take longer to complete their studies, targeted interventions such as counselling and tutoring can be promoted, potentially improving completion rates and educational outcomes without having to use as many resources.
In Large Eddy Simulation (LES), the cost of resolving the boundary layer on a solid wall boundary is high. One way to overcome this difficulty is to employ a wall model that can provide the ...approximate wall boundary conditions into the LES solution. In addition to the wall model, selecting a proper sub-grid model in the LES solution can affect computational time. In this study, the applicability of the Smagorinsky sub-grid model and of a simple wall model was investigated by simulating the turbulent flow past the square and circular cylinders, which are relevant case-studies for marine structures supported by piles. The simple wall model is based on the turbulent boundary layer equations. A solution procedure was developed to solve the set of the flow equations and then calculations were performed by considering different values of the Smagorinsky coefficient and different definitions to compute the spatial filter width scale. The corresponding numerical results are in good agreement with those extracted from available experimental and numerical data at different cylinder Reynolds numbers. The solution procedure used in this study has low computational cost such that all calculations could be performed on a single computer in a short period of time.
•The applicability of the LES Smagorinsky model together with a simple wall model was investigated in this study.•The solution procedure used in the present study has low computational cost.•The mean flow characteristics around the square and circular cylinders were good predicted.•The numerical results were found to largely depend on how the spatial filter width is estimated in the solution.
The prediction of scour evolution at bridge foundations is of utmost importance for engineering design and infrastructures’ safety. The complexity of the scouring inherent flow field is the result of ...separation and generation of multiple vortices and further magnified due to the dynamic interaction between the flow and the movable bed throughout the development of a scour hole. In experimental environments, the current approaches for scour characterization rely mainly on measurements of the evolution of movable beds rather than on flow field characterization. This paper investigates the turbulent flow field around oblong bridge pier models in a well-controlled laboratory environment, for understanding the mechanisms of flow responsible for current-induced scour. This study was based on an experimental campaign planned for velocity measurements of the flow around oblong bridge pier models, of different widths, carried out in a large-scale tilting flume. Measurements of stream-wise, cross-wise and vertical velocity distributions, as well as of the Reynolds shear stresses, were performed at both the flat and eroded bed stages of scouring development with a high-resolution acoustic velocimeter. The time-averaged values of velocity and shear stress are larger in the presence of a developed scour hole than in the corresponding flat bed configuration.
•This study establishes a strong correlation between the RAPID score and 3-month mortality in patients undergoing lung decortication for pleural empyema.•Patients were stratified into low, medium, ...and high-risk groups based on the RAPID score, demonstrating that this approach can be valuable in identifying patients with a higher likelihood of complications. This can inform treatment planning and post-operative monitoring.•While the results suggest a strong correlation, prospective studies are needed to fully validate the use of the RAPID score in this population. This underscores the importance of future clinical research to enhance the selection of the initial treatment for patients with pleural empyema.
: This study aims to correlate the RAPID score with the 3-month survival and surgical results of patients undergoing lung decortication with stage III pleural empyema.
: This was a retrospective study with the population of patients with pleural empyema who underwent pulmonary decortication between January 2019 and June 2022. Data were collected from the institution's database, and patients were classified as low, medium, and high risk according to the RAPID score. The primary outcome was 3-month mortality. Secondary outcomes were the length of hospital stay, readmission rate, and the need for pleural re-intervention.
: Of the 34 patients with pleural empyema, according to the RAPID score, patients were stratified into low risk (23.5 %), medium risk (47.1 %), and high risk (29.4 %). The high-risk group had a 3-month mortality of 40 %, while the moderate-risk group had a 6.25 % and the low-risk group had no deaths within 90 days, confirming a good correlation with the RAPID score (p < 0.05). Sensitivity and specificity for the primary outcome in the high-risk score were 80.0 % and 79.3 %, respectively. The secondary outcomes did not reach statistical significance.
: In this retrospective series, the RAPID score had a good correlation with 3-month mortality in patients undergoing lung decortication. The morbidity indicators did not reach statistical significance. The present data justifies further studies to explore the capacity of the RAPID score to be used as a selection tool for treatment modality in patients with stage III pleural empyema.
The present study aims to contribute to the numerical simulation of the flow behavior around a complex bridge pier with the scoured bed. For this purpose, a custom Large Eddy Simulation model was ...developed in which the pier and bed geometries are modeled in a structured grid system with orthogonal grid lines. The top free surface was treated as a shear-free rigid-lid. Moreover, a wall function was employed at the wall boundaries to consider the wall roughness effect on the predictions. This way, reliable numerical simulations could be performed at high Reynolds numbers with low computational cost. The developed numerical model was firstly validated by considering two cases (flow over periodic hills and flow around a single bridge pier on a scoured bed) and then the model was applied to a complex bridge pier for a scoured bed. The obtained numerical results were found to be in good agreement with the corresponding experimental and numerical results. Moreover, this study enabled to characterize the most relevant flow features of the studied cases. Overall, the highest values of the flow parameters and the small flow structures were numerically predicted in the regions where no experimental results are available due to measuring instruments limitations. According to the obtained results, the present numerical model can be considered as an adequate tool to investigate the turbulent flow features near complex geometries in a simple, fast and accurate way.
•Developing a numerical model to predict the flow features around complex geometries.•Validating the model by considering two different benchmark cases.•Applying the model to investigate the flow around a complex pier on the scoured bed.•Accurate prediction of the flow structures for the studied cases.
Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common. ...Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics. This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections. A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others. Four configurations with different bed discordance ratios were investigated. The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces. The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step. Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio. It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently.
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