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The study compares the environmental impacts of 500 mL water bottles produced from corn-based polylactide (PLA) and PET. The results of cradle-to-bottle factory gate assessment revealed that the usage of PLA granules instead of PET granules would reduce the net global warming potential and cumulative nonrenewable energy demand of bottles by 30.9% and 32%, respectively. However, if no credits are given for atmospheric CO2 fixed by corn, and the energy in corn-feedstock is accounted for, the advantages of PLA would be largely diminished. Keywords: polylactide, PET, bottles, life cycle assessment

Orthodontic treatment with the clear plastic aligner is becoming one of the most popular treatment options among adults and teenagers. The high precision of the virtual planning of the case leads to well fitted thermoformed plastic aligners and an individualized treatment for each patient. Several cases were treated with Clear Aligner therapy. All treatment outcomes were previsualized with the digital OrthoAnalyzer CAD software (3Shape) in order to design specific appliances for specific dental movements, with a lower risk of root resorption or other secondary effects. All desired dental movements can be measured and then transposed into a series of amorphous plastic aligners. Patient compliance and communication with the dental laboratory are enhanced due to the continuous developing of the CAD/CAM technology and Clear Aligner system. Keywords: digital setup, OrthoAnalyzer, plastic aligners

The paper presents, from a comparative point of view, methods to increase the controllability of a drone. An important step in increasing the controllability is using light weight and resistant materials for the rotating parts of the drone. Also, the controllability can be increased by studying the structure of the propeller in order to reduce its moment of inertia. Keywords: drone, moment of inertia, propeller, controllability, carbon fibre

The prediction of polymer properties, based on its composition, it is a complex problem with no easy method to obtain directly and accurately results. Among the tribological properties, the friction coefficient and wear rate are the most interesting ones. The polymers based on epoxy resin, with clay as filler, show different properties depending on the clay concentration. This paper presents an analysis of the polymer properties variation with its filler concentration. Due to the tribological processes complexity, mechanical and thermal properties must be taken into account. The aim of this study is to find an optimal concentration value, with minimal influence on polymer properties, using neural network models. All value properties were used in order to optimize and predict the composite properties. Keywords: polymer properties, tribology, filler concentration, neural network, prediction

This paper had as special-purpose rendering the enhancing of WNR. 1.2083 steel’s properties by vacuum heat treatment, in protective atmosphere, in order to find adequate solutions for the improvement of the tools destined for the injection molding of PBT reinforced with up to 45% fiberglass, for the total cost of a mold production project divided per the total number of the resulted pieces from that project to reach its minimum value. For that purpose to be achieved, the use of high performance steels with special alloying concept and distinct production technique is mandatory. Although the electroslag remelting process ensures a smaller number of non-metallic inclusions and a homogenous structure characterized by isotropic properties, this has to be extended after heat treatment also. By identifying the problems involved in the injection process PBT reinforced with up to 45% fiberglass, the right characteristics of the WNR. 1.2083 steel were established. In order for those characteristics to be reached, the execution of the proper heat treatment in vacuum furnaces, with protected atmosphere, will be presented in this paper. Keywords: reinforced PBT, fiberglass, heat treatment, vacuum, low tempering, distortion

This work investigates the mechanical properties of polyurethane rigid foams by means of Dynamic Mechanical Analysis (DMA) tests and Impulse Excitation Technique (IET). DMA tests were performed in single cantilever with a sweep in temperature (from -50 °C to 100 °C) and frequency (from 1 Hz to 100 Hz), not determining glass-transition in the test parameter interval. IET tests were used to determine the dynamic modulus of elasticity, showing good accordance with DMA results Keywords: PUR foams, DMA tests, impulse excitation technique

The aim of the present study was to compare the retention rate and caries-preventive efficiency of two types of sealing materials : a glass ionomer cement (Ionofil plus) and a nano-hybrid resin sealant ( Grandio Seal) over a 2-year period. 84.78% with resin composite sealings and 7.39% of the glassionomer sealings were fully retained. New caries lesions were found in 7.82% of the glass ionomer sealed surfaces and 5.65% of the resin sealed surfaces. It can be concluded that Ionofil plus and Grandio Seal exhibit similar caries preventive effects. Keywords: dental sealing; Ionofil plus; Grandio Seal; retention rate; caries outcome

Severe plastic deformation (SPD) is a manufacturing technique for producing bulk ultrafine grained materials and nanomaterials, the advanced grain refinement obtained by SPD substantially improving structural and physico-mechanical characteristics for the processed material. Equal-channel angular pressing (ECAP), the main SPD technology, entails pressing test samples through a die containing two channels equal in cross section and intersecting at a certain angle. The billet theoretically deforms by simple shear and retains the same cross sectional area to allow repeated pressings for several cycles. A commercial Al-Mg-Si alloy (6063- T1) was investigated in this study. As-received 6063-T1 alloy was firstly analyzed in OES and XRD tests. The specimens were subsequently processed at ambient temperature for a number of passes up to nine (one, three, six and nine ECAP passes), using a die channel angle of 100°. After ECAP, samples were cut from each specimen (ECAP treated and as-received) and prepared for microstructural investigations (SEM) and mechanical testing (compression and microhardness tests, fracture surfaces analysis). Furthermore, multiple correlations between ECAP processing parameters and the resulting microstructure and mechanical properties for the ECAP treated 6063-T1 alloy were also determined. Keywords: ultrafine-grained materials, aluminum alloys, severe plastic deformation, equal-channel angular pressing

Hormones are chemical substances which transmit a message as a signal within a physiological system between the place where they are secreted and the place of their receptors where they have the biological action. In the last decades the number of studies on phytohormones has increased continuously. In this study, polyurethane microstructures with and without brassinolide were synthesized in order to assess the release rate. Two different types of drug carriers were obtained (ether- and ester-based microstructures) and the evaluations were done by using two different methods: the measurement of microstructures’ size and the determination of free brassinolide concentration. The results suggest that ester-based polyurethane microstructures degrade faster and the two methods present very similar results. Keywords: brassinolide, drug carrier, DSC, polyurethane, UV-Vis, zetasizer

An increasing number of railway vehicles are using rubber springs as suspension elastic elements. Rubber is a suitable material for suspension purposes due to of its intrinsic properties and due to of the variety of forms into which it can be made. The clouth-type rubber spring may be used in both primary and secondary suspension of the vehicle and it may ensure the desired characteristics by setting the shape of its metallic components. In the present paper, a finite element static analysis was performed regarding the deformation of the clouth spring rubber under the action of various loads: vertical, longitudinal and transversal. The simulations allowed determining the distribution of deformations within the rubber element, the magnitude and the location of the largest deformation. Keywords: rubber, railway vehicle, suspension, clouth-type spring