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The purpose of this study was: Structural characterization of two commercial nanocomposite materials (Premise ™/Kerr Corp and Tetric EvoCeram®/ Ivoclar-Vivadent); Evaluation of the marginal adaptation and adhesive interface achieved with two commercial adhesive systems (Optibond SoloPlus ™/Kerr Corp and G-Bond ™/GC). Investigation was done using electronic scanning microscopy (SEM).

Medicinal plants continue to be of real interest to researchers in interdisciplinary fields such as chemistry, pharmacy, medicine. Due to the metabolites in which it abounds, the plant material can successfully represent both a prophylactic and curative treatment. At present, countless studies, both in vitro and in vivo, are conducted to elucidate the pharmacological effects and establish the mechanisms involved. The actual experiment was purposed to evaluate the activity of raw birch bark, apple pomace and olive leaves extracts rich in triterpenes, formulated as PLGA nanoparticles, on normal/healthy different cell lines immortalized and of primary origin, such as keratinocytes, dermal fibroblasts, and gingival fibroblasts.

Given the structural resemblances between glass fiber and asbestos, it is important to understand the mechanisms through which exposure to glass fibers may affect the respiratory system. To study the effect of glass fiber on rat lung through intratracheal exposure, considering the subject’s weight variation, together with haematological parameters, C-reactive protein (CRP), total number of lymphocytes, and IL8 concentration in bronchoalveolar lavage. We performed an intratracheal instillation study on four groups of 8 randomly selected Wistar rats, by administering 3 different doses of glass fiber. The hematocrit value was an indirect indicator of chronic hypoxemia; leukocytes and the C-reactive protein assessed systemic inflammation, and total number of lymphocytes and IL8 concentration in bronchoalveolar lavage fluid determined the lung’s inflammatory response. Weight variation evaluated in all 8 measurements revealed no statistically significant changes (p=0.768). The decrease in mean blood leukocytes was interpreted in relation with the glass fiber dose, with a statistically significant difference between the study groups (p=0.003). Statistically significant differences were found in the CRP values, with dose correlations (p[0.001). The bronchoalveolar lavage fluid showed increased levels of IL-8 (p[0.05), and decrease of lymphocytes (p[0.001) in correlation with the administered glass fiber dose. The inflammatory response following exposure to glass fibers in rats is correlated with administrated glass fiber dose. The alterations described as a result of intratracheal glass fiber instillation could predict the effects which occupational exposure to glass fiber may produce in humans.

Oestrogen hormones play key roles in the human body, are involved in complex mechanisms, both beneficial and unwanted. Because semisynthetic oestrogens are commonly used today in various hormonal therapies, they has inevitably been linked to the appearance of certain carcinogenic processes, which are primarily based on oestrogen-based drugs, either as initiators or promoters. A promising alternative that can help reduce unwanted effects is to capture the active substance in a polymeric matrix that is capable of retaining its biological activity. In this study, activity on the viability of breast cancer cells with expressed oestrogen receptors of a polymeric formulation with ethinylestradiol and polylactic acid was evaluated.

This research focuses on the analysis of acacia wood reinforced PLA/PHA blend composites. Acacia wood was processed into small chip particles, which were mixed with pure PLA, pure PHA and PLA/PHA blend. The wood was treated using acetic acid and sodium bicarbonate. It was then compressed into sheet film. The micrograph shows that the PLA and PHA mixture create an interlocking continuous structure and the addition of wood strengthens interlocking between PLA and PHA. Mixtures of this blend also reduce bubble and crack, and create new properties superior than the earlier properties of existing PHA and PLA.

This work deals with the problem of developing vibration damping polymeric materials which are effective at low temperatures (from minus 40 to 0°C). Due to the fact that the vibration damping efficiency in the composite is mainly determined by the properties of the polymer matrix, it is necessary to study its properties depending on the type and amount of structure-forming parameters. The purpose of the work is to determine the changes in the dynamic properties of the polymer composition based on butyl rubber, EPDM, ethylene-vinyl acetate copolymer (EVA) filled with increasing amount of calcium carbonate. The leading methods of studying this problem were the method of scanning electron microscopy and the method of dynamic mechanical analysis. It has been stated that the selected polymers can be considered as competent candidates for damping materials at low temperatures, and the calcium carbonate filler allows more fully to realize the vibration damping properties of the polymer. The obtained dependences can be used as initial data for analytical predicting of damping properties of polymer composites.

The three-dimensional printing is a manufacturing method involving the addition of materials by using certain principles valid in printing techniques. There are various techniques of a three-dimensional printing method and the most of them could be applied inclusively to generate objects of polymers. The objective of the research presented in this paper was to analyze the capabilities of 3D printing process or equipment of generating fine details and to identify a way of evaluating these capabilities when using polyester PLA as filament material. The systemic analysis of the printing techniques which use a fused polymer filament deposition showed that there are some groups of factors able to affect the obtaining of fine details. An experimental research was designed in order to highlight the influence exerted by the diameter of the nozzle orifice and by the values of sharp angles of isosceles triangles on the heights of these triangles, thus obtaining an image concerning the possibilities of generating sharp edges by three-dimensional printing. To evaluate the capacity of the 3D printing process of obtaining thin walls, a spiral including linear segments with a decreasing thickness from 1 mm was also achieved on the test piece. By mathematical processing of the experimental results using a specialized software, empirical mathematical models were determined to evaluate the intensity of influences exerted by the two process input factors on the heights corresponding to isosceles triangles characterized by sharp angles.

The main factors that affect the strength of adhesive joints are the exposure to moist environments and high and/or low temperatures. The objective of this paper is to measure the water diffusion in adhesives modified with thermally expandable particles (TEPs) and assess the joint strength of water saturated modified adhesives. Bulk specimens were used to measure the diffusion coefficient of water in a TEPs-modified adhesive. The tensile data as a function of TEPs content, moisture uptake and temperature was measured. It was found that the presence of moisture and the temperature affect the mechanical properties of TEPs-modified adhesive. Further, a scanning electron microscope (SEM) analysis was performed in order to examine the fracture surfaces of the tensile specimens tested as a function of temperature and water uptake. SEM analysis showed that the absorbed moisture and temperature change the fracture mechanisms and the morphology of the specimens.

In this study, capillary rheological tests were performed on polypropylene filled with multi-walled carbon nanotubes (PP/MWCNT) to determine the melt flow curves and pressure-Volume-Temperature (pVT) diagrams. Based on the experimental data, master viscosity curves were constructed using the time-temperature-superposition principle and the Cross and Carreau-Winter models, while the pVT data were fitted to the Tait equation in both liquid and solid states. Results show that the melt shear viscosity decreases with increasing melt temperature and shear rate and increases with MWCNT wt.%. All composites display shear-thinning behavior in the range of medium to high shear rates. The specific volume of PP/MWCNT composite decreases with increasing MWCNT wt.% and pressure and increases with increasing temperature.

The aim of this study is proposing a combination of measurements to assess the functional variability of collagen membranes used in Guided Bone Regeneration (GBR) and Guided Tissue Regeneration (GTR) techniques. As far as clinical applications are concerned, a proper qualification is critical when deciding, among commercially available collagen membranes, upon the most appropriate one for each specific clinical case. Two commercially available collagen membranes, namely Collprotect® and Jason®, were considered for the experimentation. After thickness and density measurements, the quasi-static behavior was studied for both membranes by means of conventional mechanical tests, i.e. tear and tensile tests, whereas their time-dependent behavior was evaluated by means of stress relaxation tests and dynamic mechanical analysis. Collagen membranes showed an elevated among samples variability. The variability within the same kind of membrane is of the same order of magnitude of the between membrane kinds variability. All the membranes showed strong time dependence both in stress relaxation and in dynamic mechanical tests. This fact should be taken under consideration for the membrane final application.