Our study’s goal was to underline the differences between the girls’ and the boys’ representative in terms of age, in what concerns the moving speed and the effort perception during the dynamic balance when walking on the slackline throughout the activities specific for the Development through Education and Adventure (DEA). The results have shown the fact that the boys have a better speed movement on the slackline rather than the girls, allowing us to conclude that the boys’ dynamic balance is superior to the girls’ balance on both studied age categories. Perceiving the physical effort through heart rate is different according to age category when walking on the slackline for the groups of the study.
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The main goal of this research study was to understand the role of the vegetable oil in the obtaining process of nanoparticles by emulsion solvent evaporation method, respectively the effect of the vegetable oil upon the final characteristics of hybrid PLGA-pomegranate vegetable oil (PMG) nanoparticles. Colloids with mean diameter around 125.6 nm (PLGA-np) and 141.7 nm (PLGA-PMG-np) were obtained. It was noted that the addition of the vegetable oil has a key role in the primary emulsification process leading to hybrid colloids with improved the uniformity (PdI) and stability of hybrid nanoparticles.
Ephedrine is an illicit drug, classified as precursor for methamphetamine, which is also used as stimulant, appetite suppressant, decongestant or asthma. In this study, novel molecularly imprinted polymer (MIP) films were prepared by sol-gel derived techniques, using N-(2-aminoethyl)-3-aminopropyltrimethoxysilane as functional monomer, to recognize ephedrine from aqueous solutions. The films were obtained by air-spraying the precursor solutions, with various concentrations of monomer and template, on glass supports. Infrared, thermogravimetry, ellipsometry, optic and atomic force microscopy analyzes of films provided information regarding the effect of molecular imprinting upon the physical properties of films. Further on, batch rebinding evaluation indicated that thinner films present high affinity for ephedrine, resulting in 6.2 imprinting factor after 15 minutes of contact, which attests the ability of the novel MIP films to recognize and rebind ephedrine.
In this study a fluid elastomer was applied by two different methods on a martensitic stainless steel substrate, in order to obtain coatings for protection against cavitation. The investigations regarding the resistance to cavitation erosion of the elastomeric coatings were carried out by the indirect vibratory method using the values of the cumulative erosion (material loss) developed during a testing period of 600 minutes with a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 50 μm. The experimental results obtained in the laboratory have been processed statistically. They clearly pointed out that the deposition method significantly influences the cavitation resistance of the elastomer.
This paper describes a hip implant model designed to assess the Fused Deposition Modeling (FDM) process for manufacturing investment casting master patterns. In addition, an indirect approach toward manufacturing master pattern via silicone rubber moulding in conjunction with 3D Printing process manufactured hip implant master pattern has been investigated. The dimensional accuracies of the manufactured AM master patterns and the wax pattern are presented. Finally, cost and lead time comparisons carried out between FDM ABS pattern manufacturing, indirect pattern manufacturing via silicone rubber moulding and conventional pattern manufacturing by metal mould are also presented.
Nowadays world is exposing a continuous spreading of composites applications and, as a consequence an enforcement of scientist efforts toward such materials design, testing and modelling. Since polymer reinforced materials are covering a huge area of applications it is obvious that the researchers interest is oriented to these materials study in all its aspects. Fabric reinforced polymers represent a very attractive solution from the manufacturers’ point of view, especially in the case of thermoset polymers where the lay-up method is the most used to form composites. This study is about tensile behavior of lamina or plies of thermoset matrix fabric reinforced materials. The aim of the study is to determine the role of the matrix and the role of fabric (fibers type, specific weight) on the tensile response to gather valuable information regarding the design of layered materials.
The purpose of this article is to present an overview of the trend of using, on a wider scale, plastics in the automotive industry. It is presented the realization of PLA-TPU-Blends with a biogenic mass greater than 90%, by mixing thermoplastic Polyurethan (TPU) with Polylactid-Acid (PLA) at IKT University of Stuttgart. In order to estimate the possibilities of use of bio-materials made from PLA and TPU, the properties were compared with standard thermoplastics such as Polypropylen (PP), Polyethylen (PE), Polyamid (PA), as well as with better performing materials from the engineering thermoplastics range. PBT, ASA and their derivatives. Notable are the properties of PLA-TPU-Blends compared with standard thermoplastics PP, PE, PA. The results show PLA-TPU-Blends superiority in Yeld strength compared to the types of Polypropylene homopolymer (PP-H), block-copolymer (PP-B) and randompolymer (PP-R), the properties being adaptable by flexible modification of the ratio between the components, according to the requirements of the application. Using suitable additives to make components compatible, there were created blends which were partially cross-linked, but their properties remain of thermoplast. When reinforcing PLA-TPU-Blends with fibers (glass and natural), the components also react with the groups (-OH) on the fiber surface, thus making a good connection between fibers and blends, which prevents the so-called pull-out-effect. PLA-TPU-Blends reinforced with natural fibers can be used to make the interior body elements of vehicles. The paper also presents a comparison between bio-materials made at IKT University of Stuttgart with Polyethylen (PE) and other industry standard bio-materials.
The article presents the technology and process, whereby a small-scale demonstration model and the real-scale prototype of vertical axis wind turbine blades are produced using rapid prototyping technology (3DP) and GFRP surface coatings, which help to improve the mechanical properties. In the end of the article the results of the production process and the advantages of combining these technologies are presented.
Explaining the phenomena occurring at the level of relative friction surfaces has become increasingly complex and often contradictory. Research over time has shown that the friction coefficient for a friction coupler is not a constant magnitude, as Amonton-Coulomb has stated, its values being dependent on a multitude of factors (normal load, slip rate, the nature of the material, the state of lubrication, etc.). The laws of the two are considered to be valid only under conditions of dry rubbing and elastic deformation of the surfaces in contact. The present paper proposes in the first part a study on the theoretical expression of the coefficient of friction. The experimental part of the paper highlights the variation of the coefficient of friction with the speed, loading and processing of the contact surface. It was made on a tribological stand of pin / disc type, and the coupler used was polymeric material called Turcit (for disc) / general purpose steel (for pine).
The aim of our study was to evaluate fracture resistance of the PMMA complete dentures and to make a comparison between the classic acrylic maxillary complete dentures and the metal-reinforced ones, in terms of fracture resistance during function and to compare the fracture pattern of the two groups of complete dentures. We used maxillary complete dentures made of heat-processed acrylate, 5 exclusively and 5 in which a metal-cast net in the form of a mesh was inserted after being casted, worn by patients for a period of 5 years. A bilateral progressive force was applied to the PM2-M1 area until the samples failed, recording the force value at which the first change occurred. A Universal Loading Machine was used. The results were analyzed using the ANOVA method. For the classic acrylic complete dentures group, the minimum fracture force value was 1060 N, the maximum fracture force value being 2443 N. For the reinforced complete dentures group, the minimum fracture force value was 3320 N, the maximum value being 3760 N. Statistical analysis of data using the ANOVA shows that the results are statistically relevant, with a p value of 0.000137 (p[0,05). All the dentures from the classic acrylic complete dentures group fractured presenting two or more fracture lines, most of them involving also fractures on the acrylic teeth and breaking into multiple pieces, while all the dentures from the reinforced complete dentures group fractured presenting one or two fracture lines, most of them without detachable fragments and involving also fractures on the acrylic teeth.