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In the recent years, the number of patients treated with fixed orthodontic appliances is permanently increasing, as well as their interest for esthetic treatment issues. One potential unwanted consequence of orthodontic therapy is the onset of white spot lesions on teeth enamel during treatment. The present review includes studies published between 2010 and 2021 on three different databases (Science Direct, PubMed, Google Scholar) regarding the implications of nanoparticles in white spots prevention. The initial databases search identified 471 entries. Following the PRISMA-P 2015 guide, 39 scientific articles were selected for full text evaluation. The studies were divided into four categories. The interpretation of studies included in this review permits us to sustain the idea that the use of nanoparticles in various orthodontic materials improves their bioactivity, decreases the biofilm appearance around components of the fixed appliances, and can even initiate remineralization in the enamel proximity. Most of the analysed articles are in-vitro studies of new biomaterials properties, in the recent years depicting an increase interest of the researchers towards randomized control trials regarding clinical use of new orthodontic biomaterials.

In construction building, the optimum insulation material thickness determines the efficiency of energy consumption. In this paper, heat transfer and the temperature distribution of recycled polymers between construction building components are investigated using theoretical and simulation methods. It has been shown that when the thickness of all recycled polymers being studied is increased, insulation improves and energy consumption decreases, indicating that XPS is the best recycled plastic and the optimum thickness is 7 cm. In this work, experimental and numerical approaches have been used, to conduct a qualitative and quantitative analysis of the thermal performance of an external wall outfitted with new insulation materials, based on the most commercialized recycled thermoplastic polymers (Polyethylene RPE, Polyethylene terephthalate RPET, and Expanded Polystyrene RXPS) waste.

In this study is presented the result obtained for the treatment of waste water from the medical sector using membrane filtration system. Polyethersulfone (PES) membranes were obtained using Dimethylformamide DMF like solvent, with different concentration to determine the rejection variation of different dyes. Membranes were obtained by the immersion precipitation method and permeation properties were determined by dead end technique. The results show that the membranes filtration method can by improved to reduce the cost of the water treatment from the medical sector. Using DMF solvent membranes with a smaller concentration of polymer have a good rejection results in comparison with other membranes obtained with different solvents.

Composites that have a good to lower weight ratio can be used to replace conventionally used Engineering Materials. The properties of natural fibers are almost equal to that of artificial fibres. Natural fibers can be used in many applications and is also a cost-effective material. Bagasse fibre reinforced with dry palm kernel fibre powder is used to improve mechanical properties and fabricated in plate form. In this research work, the input constraints that have been used to fabricate the plate are 10, 20, 30 wt% of bagasse fibre, 10, 20, 30 wt% of palm kernel fibre, at 10, 15, 20 MPa compression pressure and 2, 4, 6 mm of speciemn thickness respectively. The optimization has been performed by Taguchi L27 orthogonal array and influence of output parameters viz. Tensile Strength (MPa), Flexural Strength (MPa) and Hardness (Hv) have been measured by using statistical analysis of variance. The multi-criteria decision making of the output parameters has been performed by Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). This research offers new insight into decision-making, particularly in the optimization part, to increase the strength and mechanical property of natural fiber composites.

This in vitro study aimed to compare the fracture resistance between pressed custom-made polyetheretherketone (PEEK) post and core and fibre reinforced post and composite core. A total of 40 single rooted extracted teeth were selected, endodontically treated, and prepared to receive the posts. Specimens were randomly divided into two main groups (n=20/group): group 1, (PEEK); group 2, fibre post. PEEK post was manufactured with a computer-aided design/computer-aided manufacturing system further divided into four sub groups (P7, P12, F7, F12) based on lengths 7 and 12 mm at which the posts were cemented. All posts were cemented with self-adhesive resin cement, and specimens were stored in 0.1% thymol solution during the experiment at all the times except during preparation and testing. A universal testing machine was used to measure the fracture resistance. The fracture resistance values (mean & SD, in newtons) were 1255N (P7), 1562N (P12), 1065N (F7), and 1384N (F12). Only P12 exhibited a significant difference (p,0.05). The turkey test showed an association between failure mode and post and- core material. In the remaining groups, most failures were nonrepairable and related to fracture. Customized post-and-cores of PEEK exhibited good mechanical performance. Their fracture resistance was comparable to that observed for fibre posts.

The high heels footwear industry is permantly evolving due to the increasing attention given to combine confort and elegance. The purpose of footwear has changed with the evolution in the fashion industry and it is no longer limited only to protect the feet. This paper represents a first step to develop customized shoes outer sole, taking into consideration the unicity of each individual anatomy. Another important aspect is the manufacturing of these outer soles using plastic materials. The additive manufacturing presents itself as a viable option in obtaing a working prototype. Based on previous research, an analysis has been performed in order to optimise the design and its functionality. The study validation has been done using FEA and Topology Opimisation.

Generally, the importance of bending test has been employed to analyse the induction level of internal resistance of its larger face size of the test speciemens. Comparatively, stress induction is quite larger at the perpendicular face, where the bending load has been initiated its point of contact. Therefore the estimation of the location of maximum stress induction on bending test specimen must be analysed for the purpose to estimate the breaking point of test specimen, which supported a lot in the lifespan estimation of a component. In this work, three different composites are selected under the category of primary composites and thereby underwent the bending testing for the purpose of material refinement to tackle compressive load based applications. Three-Point flexural tests are conducted on the primary composites. The internal molecules bonds at peak loads are visulaized through SEM approach. Thus, the perfect inital and boundary conditions for computational strurtual analyses are found out. Ansys Workbench is an advancement tool, which is used in this work for composite generation and structural simulations. All the computational tests are effectively executed with the help of advanced coupling facility between different working environments. Finally, the numerical results are compared with experimental results and then suitable material is shortlsted based on high load withstand capacity. Additionally, the conventional analytical approaches are used to validate the flexural outcomes. Further, the advanced finite element analyses are expanded to advanced composites materials such as nanocomposites, shape memory alloys based composites, and sandwich composites. From the above all studies, the superior material is finalized based on the outcomes of this multi-inclusive investigations.

In this paper we have created some composites reinforced with corn cob powder and the matrix was made by a combination between Resoltech 1050 resin with its Resoltech 1058 hardener. For the composites manufacturing, we have used the manual casting technique. For the new manufactured composites, we have determined the mechanical properties from the tensile test according to ASTM D3039: Young modulus, breaking strength and elongation at break. We have also molded samples for the compression test according to ASTM D695-15 and we have determined the breaking strength. The tensile and compression tests were made on universal testing machines. In the end, we have determined also the dynamic mechanical properties for the studied material by clamping the samples at one edge and leaving the samples unconstrained at the other edge. At the unconstrained edge we have placed a Bruel&Kjaer accelerometer which recorded the samples free vibrations. From the free vibrations recording and Euler-Bernoulli theory, we have determined the next dynamic mechanical properties: damping factor per unit mass and length, eigenfrequency, dynamic modulus of elasticity, loss factor and dynamic rigidity. From the experimental results, we have obtained increased breaking strength values for the proposed material at compression compared to the tensile test. Compared to similar materials studied in the engineering literature, we have obtained increased compression breaking strength.

The extension of 3D printing processes for parts made of polymeric materials highlighted the possibility of manufacturing threaded surfaces through such processes. In principle, the operation of a threaded joint involves tensile forces in the threaded rod. The dimensional characteristics of the threaded surface and some input factors in the 3D printing process can influence the tensile strength of threaded rods made of polymeric materials. An experimental research aimed at the tensile behavior of a threaded joint was designed, using a plastic screw and a special steel nut. A factorial experiment was designed and implemented to identify an empirical mathematical model capable of highlighting the influence of the dimensional characteristics of the threaded surface and some of the input factors in the 3D printing process on tensile strength. The test samples from polymeric materials were manufactured by 3D printing, then subjected to tensile tests. The mathematical processing of the experimental results allowed the determination of a mathematical model that allows the inclusion of the ordering of the factors taken into account in terms of the intensity of the influence that these factors exert on the tensile strength of the threaded rods. It was found that the diameter of the threaded rod exerts the strongest influence on the tensile strength of the threaded rod obtained by 3D printing, increasing the diameter of the threaded rod causing an increase in the maximum deformation of the rod. Increasing the thread pitch leads to a decrease in the maximum deformation of the threaded rod.

The effect of bamboo fiber content on mechanical properties, moisture permeability and light transmittance of composite membrane was studied. The results show that the tensile strength of the composite film is increased by 30%, and the mechanical properties of PVA film are improved obviously with the addition of bamboo cellulose, which can be used as a good reinforcing material of PVA matrix. Bamboo cellulose composite film is a kind of transparent material because of its high light transmittance.