In vitro assessment of dry powders for inhalation (DPIs) aerodynamic performance is an inevitable test in DPI development. However, contemporary trends in drug development also implicate the use of in silico methods, e.g., computational fluid dynamics (CFD) coupled with discrete phase modeling (DPM). The aim of this study was to compare the designed CFD-DPM outcomes with the results of three in vitro methods for aerodynamic assessment of solid lipid microparticle DPIs. The model was able to simulate particle-to-wall sticking and estimate fractions of particles that stick or bounce off the inhaler’s wall; however, we observed notable differences between the in silico and in vitro results. The predicted emitted fractions (EFs) were comparable to the in vitro determined EFs, whereas the predicted fine particle fractions (FPFs) were generally lower than the corresponding in vitro values. In addition, CFD-DPM predicted higher mass median aerodynamic diameter (MMAD) in comparison to the in vitro values. The outcomes of different in vitro methods also diverged, implying that these methods are not interchangeable. Overall, our results support the utility of CFD-DPM in the DPI development, but highlight the need for additional improvements in these models to capture all the key processes influencing aerodynamic performance of specific DPIs.

This study focuses on preparing piezoelectric polyvinylidene fluoride (PVDF) nanocomposites reinforced with silver nanoparticles (AgNPs) using an electrospinning process. The aim of this study is to assess AgNPs’ influence on the piezoelectric properties of PVDF and, therefore, create an optimal piezoelectric composite with enhanced properties, enabling its application in various fields both as sensor and actuator. Because electrical stimuli have proven to have a positive influence in tissue engineering, combined with AgNPs, which have antimicrobial properties, these composites demonstrate a promising opportunity for application as biomedical scaffolds. The proposed scaffolds were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. In addition, mechanical properties are studied through tensile tests, while piezoelectric response is measured on an in-house built setup coupling mechanical stimuli and electrical response monitoring. An experimental test was combined with numerical simulations through the COMSOL Multiphysics version 6.3 software package, and this paper also presents a short review of the numerical and analytical methods used for the modelling and simulation of piezoelectric composites.

The development of novel dry powders for dry powder inhalers (DPIs) requires the in vitro assessment of DPI aerodynamic performance. As a potential complementary method, in silico numerical simulations can provide additional information about the mechanisms that guide the particles and their behavior inside DPIs. The aim of this study was to apply computational fluid dynamics (CFDs) coupled with a discrete phase model (DPM) to describe the forces and particle trajectories inside the RS01^® as a model DPI device. The methodology included standard fluid flow equations but also additional equations for the particle sticking mechanism, as well as particle behavior after contacting the DPI wall surface, including the particle detachment process. The results show that the coefficient of restitution between the particle and the impact surface does not have a high impact on the results, meaning that all tested combinations gave similar output efficiencies and particle behaviors. No sliding or rolling mechanisms were observed for the particle detachment process, meaning that simple bouncing off or deposition particle behavior is present inside DPIs. The developed methodology can serve as a basis for the additional understanding of the particles’ behavior inside DPIs, which is not possible using only in vitro experiments; this implies the possibility of increasing the efficiency of DPIs.

Hydroxyapatite (HAP) inserts minimize restoration contraction by constituting a major part of the restoration; however, their effect on the relaxation of tooth tissues has not been previously tested. Finite element analysis was employed to estimate stress and displacement when HAP inserts with a thickness of 1.7 mm or 4.7 mm and a diameter of 4.7 mm were used to substitute for dentin. The volumetric contraction of the composite during polymerization, simulated through steady-state heat transfer analysis, yielded a contraction rate of 3.7%. Descriptive statistics revealed that the incorporation of HAP inserts reduced the displacement of dentin, enamel, and restoration caused by contraction by 44.4% to 66.7%, while maximal stress was reduced by 8.1% to 52%. Subsequent loading on the occlusal tooth surface showed that displacement values decreased by 12.1% to 33.3%, while maximum von Mises stress in enamel decreased by 32.8% to 40.6% with the use of HAP inserts. Although the maximum stress values in dentin were not significantly decreased (3% to 8.8%), the stress located at the bottom of the cavity was notably reduced, particularly in deep cavities at root canal entrances. The use of HAP inserts in restorative dentistry provides benefits for the preservation of prepared teeth, especially in preventing irreparable vertical root fractures of endodontically treated teeth.

Phase-field damage modeling (PFDM) is very popular among researchers and engineers, because it offers applications to various fields of interest. Investigating damage in structures and predicting its evolution, which can lead to material stiffness degradation and structural failure, is the most interesting aspect. Various research groups at the top world universities have implemented the latest findings into the commercial and research finite element method (FEM) codes, and the PFDM will probably be recognized technique for structural safety monitoring. However, the practical application is in one of the top interests, but some disadvantages decrease the possibility of efficient and accurate FEM simulations. One of them is the need for a fine FE mesh in the zone where material damage is expected, which makes models with large numbers of degrees of freedom and huge computational time. In this scope, it is important to implement the PFDM for various types of finite elements such as 2D axisymmetric elements, which can decrease the size of the problem by modeling only a cross-section of the axisymmetric structure. In this paper, we have implemented a previously developed PFDM theory into the 2D axisymmetric element and compared the simulation results to the 3D solid element for the well-known large strain circular bar example.

In the modern contemporary environment, simultaneous monitoring of physical and mental strain is very important in order to improve ergonomic conditions and the health of workers. This research paper presents a multimodal approach to assessing the physical and mental strain of workers during assembly activities. The proposed model combines the RULA (Rapid Upper Limb Assessment) method for assessing ergonomic risk and the EEG (electroencephalography) method for evaluating mental strain. Through an experimental study conducted on a sample of 7 subjects, the implications of assuming certain body postures on the physical and cognitive state of the subjects were analyzed. The results indicated a significant association between the adoption of non-physiological and non-ergonomic body postures and increased mental effort, which indicates the need for an integrated assessment when designing ergonomic workplaces. The results obtained showed that the application of ergonomic principles contributes to the reduction of physical and mental strain. The results also confirm that high levels of physical strain lead to changes in the brain activity of the subjects that correspond to increased mental effort. The proposed approach can serve as a basis for the development of advanced systems for monitoring and optimizing worker performance and well-being.