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The aim of this study is to compare two different methods used for obtaining printed dental models -intraoral scanning and extraoral scanning; the comparative analysis was made in correlation to the accuracy of the traditional plaster cast model. Nine dental models were obtained: three plaster cast ones, three printed after intraoral scanning and there printed after impression scanning. A total of 137 measurements (arch and tooth measurements) were done on the three types of models and a statistical evaluation was performed (t-test, Fisher Test). Our results highlighted that 3D printed dental models represent a reliable option for clinical application.

The application of plastic materials in various areas of contemporary technology can lead to improvements in the function, quality and performance of engineering components. When determining the field of use of these materials, it is necessary, in addition to knowing the physical and mechanical properties, information about their behavior in service under the influence of the operating and environment factors. Compared to metallic or ceramic materials, polymeric materials exhibit a wide range of scratching deformations in a narrow range of pressure, speed, temperature, lubrication etc.In this paper is proposed a penetration model of a flat surface (from polymeric material) with a rigid conical penetrator and the determination of the flat surface material response mode. The penetration method corresponds to the deformation produced by the asperities in practice.The comparison of the experimental and the theoretical results confirms the veracity of the model and corresponds with many of the experimental results obtained in the specialized works.Based on the proposed models, maps can be produced, that can illustrate the response of any polymeric surface in contact with an abrasive material.

Reduced graphene oxide (r-GO) was synthesized chemically and it was characterized using Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The results revealed that the product r-GO is nano-sheets with non-smooth surface; the size of the obtained nano-sheets ranged from 20 to 100 nm. The well characterized nano-sheets were subjected to cytotoxicity test; results demonstrated that the nano-sheets show low cytotoxicity on the human cell line compared with the chemical nematicide. The r-GO was tested against the nematode during their life span and it was observed that the r-GO is capable to reduce the nematode gall number and egg mass of 94% and 99%, respectively. Moreover, the toxicity of the r-GO against the Juvenile (J2) root-knot nematode (Meloidogyne incognita) was also examined either in laboratory or under the greenhouse conditions. On the other hand, the treatment with the r-GO under greenhouse conditions showed higher mortality of the J2 of 98.5% compared with nematicidal treatment of 96% in a soil infested with M. incognita. Also, the same treatment was sufficient in inducting the growth of tomato plants: fresh weight of the shoot system increased with 30% and of the root system increased up to 285%; dry weight of the shoot system increased with 128% and of the root system increased up to 480%. r-GO has a high nematicidal activity and it is safe for human. The r-Go could be used as safe nematocide because it is safe, cheep, could be produced at large scale, and it is a good additive for the soil.

This paper analyzes the indentation hardness and the indentation elastic modulus variation depending on the variation of the grind percentage of polymer, when the other factors that can influence the injection molding remain unchanged. The analyzed polymers were: acrylonitrile butadiene styrene ABS MAGNUM 3453, polyamide PA 6.6 TECHNYL AR218V30 Blak and polyoxymethylene POM EUROTAL C9 NAT. The samples that were studied had different compositions in new and grinding material. The G-Series Basic Hardness Modulus at a Depth method was used. The increase of the grind percentage of ABS (from 0 to 100 %) leads to insignificant changes in the indentation hardness, indentation modulus, and maximum force applied to samples of tested material. The maximum hardness (0.137 GPa) of PA 6.6 is recorded in the case of the sample with 80% grind content, and the maximum hardness of POM is recorded as well in the case of the sample with 80% grind content, as being 0.215 GPa. The variation of the grind content in the analyzed samples determines changes in the evaluated parameters, depending on the type of polymer. Combining the new material with grind in proportions experimentally established for each techno polymer leads to changes in their mechanical properties.

Breast implants are nowadays used in breast augmentation and reconstruction. These can have a silicone or saline filling and a textured or smooth surface. Textured implants have been more frequently used due to their capacity of impairing moving and developing capsular contracture. Breast associated anaplastic large cell lymphoma has been correlated with the presence of textured implants even if the pathogenesis is not entirely understood and other factors might be involved.

Plasticity of the steel -as an important property of the material -has the role to show the capability of the steel to support plastic deformation necessary to obtain pieces for industry. Plasticity can be influenced by cooling regimes from higher temperatures in the cases of non-conventional treatments. An important factor is the cooling speed of the steel from higher temperatures during non-conventional treatment applied after lamination of the material. To modify the speed of the cooling, the medium of the cooling has been changed. The samples of the steel have been cooled in normal condition, in metallic box and using a jet of cold air. The evolution of the plasticity was studied taking in consideration the evolution of some characteristics. This paper might be considered as a review of the researches from the last years.

Waste electrical and electronic equipment (WEEE) generated in large amounts due to the development of IT and telecommunication industry is considered an important concern for environmental protection. The complex polymer composition of WEEE can be determined in order to consider a proper recycling process for polymeric materials. The aim of the study was to identify the constituent polymers by: density, burning test, solubility, Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), thermo-gravimetric analysis (ATG). The research led to a majority of polystyrenic polymers, together with polyesters, polycarbonates and polyamides.

This study compares the values of the electromagnetic fields generated by three types of microwave ovens with the values available in scientific literature, guides and protocols, considering their impact on human health. Variations in electromagnetic radiation have been determined during and outside the operating time of the microwave ovens at different distances from the oven and in different positions, thereof. The obtained data show higher values of the radiation leakage during operation than those provided by the regulations in force, for all types of studied ovens. The results of the study suggest the need to reduce the time spent near these devices and to optimize the equipment in order to reduce these radiation leakages.

In order to identify the causes that led to microbiological degradation by biofouling increases a top coat painting layer applied to a railway bridge was analyzed by both FTIR and the DSC methods; the analysed painting material was that used to paint the bridge in 2013.The determinations were performed comparatively on samples of a similar painting material after 10 days of curing in a natural atmosphere at 25 ± 5 °C, after 60 days of storage under laboratory conditions (22 ± 5 °C, RH 60 ± 10 %, natural lighting), and on samples from the painting material of a certain railway bridge after approx. 4.5 years (exposed natural weathering of temperate climate with Mediterranean influences). From FTIR determinations, the amount of oxygen containing groups (C = O, C-O, C-O-C, -HO) resulted from ageing under various conditions of the painting material.From DSC determinations, the resistance of the paint to the oxidative degradation decreases with the ageing time as resulted from oxidation onset temperatures and oxidation activation energies values – which decreases with 4 kJ / mole (about 2.2 %) in only 60 days of storage in the laboratory and with 7 kJ/mole (about 3.9 %) following exposure to 100 w/m2 for only 15 h and 29 kJ / mole (over 16 %) after exposure to 4.5 years of natural weathering.

The photochemical degradation of polyolefin-TiO2 composite films was investigated and described in relationship with the concentration of photocatalyst and after different exposure times. UV-Vis-NIR and IR spectra reveal the presence of various degradation products, which are in direct connection with the photodecomposition mechanism. Various ratios between the absorbance of some typical IR characteristic bands can lead to the evaluation of photocomposition of polyethylene and polypropylene composite films containing TiO2 nanoparticles.The results show that the photocatalytic degradation of composites is significantly faster than the simple photolytic decomposition of pure polypropylene and polyethylene and could be used as a solution for the destruction of this type of wastes.