Iskanje po katalogu digitalne knjižnice

Opis: Traditional prosthetic liners are often limited in customization due to constraints in manufacturing processes and materials. Typically made from non-compressible elastomers, these liners can cause discomfort through uneven contact pressures and inadequate adaptation to the complex shape of the residual limb. This study explores the development of bioinspired cellular metamaterial prosthetic liners, designed using additive manufacturing techniques to improve comfort by reducing contact pressure and redistributing deformation at the limb–prosthesis interface. The gyroid unit cell was selected due to its favorable isotropic properties, ease of manufacturing, and ability to distribute loads efficiently. Following the initial unit cell identification analysis, the results from the uniaxial compression test on the metamaterial cellular samples were used to develop a multilinear material model, approximating the response of the metamaterial structure. Finite Element Analysis (FEA) using a previously developed generic limb–liner–socket model was employed to simulate and compare the biomechanical behavior of these novel liners against conventional silicone liners, focusing on key parameters such as peak contact pressure and liner deformation during donning, heel strike, and the push-off phase of the gait cycle. The results showed that while silicone liners provide good overall contact pressure reduction, cellular liners offer superior customization and performance optimization. The soft cellular liner significantly reduced peak contact pressure during donning compared to silicone liners but exhibited higher deformation, making it more suitable for sedentary individuals. In contrast, medium and hard cellular liners outperformed silicone liners for active individuals by reducing both contact pressure and deformation during dynamic gait phases, thereby enhancing stability. Specifically, a medium-density liner (10% infill) balanced contact pressure reduction with low deformation, offering a balance of comfort and stability. The hard cellular liner, ideal for high-impact activities, provided superior shape retention and support with lower liner deformation and comparable contact pressures to silicone liners. The results show that customizable stiffness in cellular metamaterial liners enables personalized design to address individual needs, whether focusing on comfort, stability, or both. These findings suggest that 3D-printed metamaterial liners could be a promising alternative to traditional prosthetic materials, warranting further research and clinical validation
Ključne besede: bioinspired design, metamaterial model, cellular structure, additive manufacturing, lower-limb prosthetic, 3D printing, finite element method
Objavljeno v DKUM: 19.09.2024; Ogledov: 0; Prenosov: 0
Celotno besedilo (8,88 MB)
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Opis: Reading and learning are changing rapidly in today's world, and educational systems sometimes fail to keep pace. To define the needs related to reading in the modern world, the Stavanger Declaration was written, stating that students should be taught online reading and learning strategies. Educators must also adapt to this. As part of the Learning, Teaching, and Training (LTT) activities, participants (21 individuals from different levels of education) were introduced to the Internet reciprocal teaching (IRT) method. The basis of this research was to find out whether we can empower educators to teach online reading, learning, and comprehension skills in a short training session using the ubiquitous topic of ecological problems as an example. We were also interested in whether a short program that empowers educators to use IRT in their classroom can influence teachers to develop students' digital literacy in their pedagogical work. The results show that the ecological issue, with its timeliness and universal presence in our lives, is an appropriate topic for educators to teach digital literacy. The participants were successful in solving the set tasks, and all of them answered that they would use the IRT method in their future pedagogical work.
Ključne besede: digital literacy, ecological problems, internet reciprocal teaching method, problem solving, teacher trening
Objavljeno v DKUM: 18.09.2024; Ogledov: 0; Prenosov: 1
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Opis: Tannins represent secondary plant metabolites that are used to control bacterial populations by chelation of essential metal ions. Their presence in food also affects the bioavailability of iron. This study investigates the influence of ellagitannins (vescalin, castalin, vescalagin, castalagin) structure and pH on the stoichiometry and formation constants of ellagitannin-Fe(II) coordination compounds. We demonstrated that ellagitannins are stable for at least one hour at pH values lower than 7.25. The spectra of neutral compounds were measured and explained with the help of TDDFT calculations. Furthermore, the pH-dependence of the ellagitannins UV–Vis spectra was examined to obtain insight into their protolytic equilibrium. Using Job’s method in the pH range 3.50–5.51, the stoichiometry of the formed ellagitannin-Fe(II) ions complexes was determined. A model explaining interactions between ellagitannins and Fe(II) ions, that took into account the protolytic equilibrium of ellagitannins, was fitted globally to all four Job plots, whereby the corresponding formation constants were obtained.
Ključne besede: Ellagitannins, Fe(II) ions chelation, protolytic equilibrium, Job’s method, model fitting
Objavljeno v DKUM: 22.08.2024; Ogledov: 52; Prenosov: 1
Celotno besedilo (3,98 MB)

Opis: The digitalization of industrial processes is being driven forward worldwide. In parallel, the education system must also be transformed. Currently, education does not follow the opportunities and development of technologies. We can ask ourselves how we can integrate technologies into a traditional learning process or how we can adapt the learning process to these technologies. We focused on robotics education in secondary vocational education. The paper contains research results from a modern learning model that addresses student problem-solving using cyber-physical systems. We proposed a reference model for industrial robotics education in the 21st century based on an innovative cyber-physical didactic model (CPLM). We conducted procedure time measurements, questionnaire evaluations, and EEG evaluations. We could use VR to influence the improvement of spatial and visual memory. The more intense representation of the given information influences multiple centers in the brain and, thus, the formation of multiple neural connections. We can influence knowledge, learning more effectively with short-term training in the virtual world than with classical learning methods. From the studied resources, we can conclude that the newer approach to teaching robotics is not yet available in this form. The emerging modern technologies and the possibility of developing training in this area should be investigated further.
Ključne besede: VR technologies, educational robotics, education, innovative learning method development, evaluation
Objavljeno v DKUM: 08.07.2024; Ogledov: 105; Prenosov: 3
Celotno besedilo (2,43 MB)
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Opis: Dopamine is an important hormone and neurotransmitter, and its levels in human fluids can indicate stress, depression, and various mental disorders. Food products, as well as medications, affect its level in the human body greatly. Therefore, dopamine monitoring is crucial, and necessary for improving the quality of life. The priority is to search for simple and environmentally friendly sensor systems for the in vitro detection of dopamine, enabling mass utilization. In this study, we explored the use of o-phthalaldehyde (OPA) as an indicator for the detection of dopamine, with fluorescence in the visible range (λex/λem = 390/455 nm), while direct dopamine fluorescence measurement was in the UV range (λex/λem = 280/320 nm). The longer excitation/emission wavelengths of dopamine-OPA complex, as well as lower detection limits, are useful for developing a simple detection method using LEDs. Three types of poloxamers were tested as additives to improve the fluorescence signal from the reaction between dopamine and OPA. Pluronic F127 led to a 16-fold increase in the fluorescence. Utilizing 4% Pluronic F127 with OPA at pH 7 resulted in a linear response within concentration ranges of dopamine (0.5–3 µM), achieving a limit of detection of 0.015 µM. In contrast, a direct detection of dopamine within the same range exhibited a detection limit of 0.13 µM.
Ključne besede: fluorometric method, dopamine, O-phthalaldehyde, Pluronic F127
Objavljeno v DKUM: 28.05.2024; Ogledov: 317; Prenosov: 11
Celotno besedilo (3,51 MB)
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