Browse Articles

The paper addresses the methodology for obtaining biocomposite structures from waste, with sound-absorbing properties, such as: thuja shells, walnut shells, pistachio shells, beech sawdust, pumpkin seeds shells and sunflower seeds shells. The experimental analysis carried out considers the study of the sound-absorbing properties held by the proposed new biocomposite materials, by determining the value of the sound absorption coefficient, reflection coefficient, impedance ratio, using the Kundt tube. The interpretation of the results obtained from the evaluation of biocomposites shows that they have sound-absorbing properties. Consequently, sound-absorbing panels with soundproofing properties can be made from these materials, which can be used in industry, transportation, construction, etc. as well as for decorative purposes in spaces such as cinemas, malls, spas, etc.

Compomers have emerged by modifying dental composites in an effort to combine their desired properties, namely their good aesthetics, with those of glass ionomer cements, namely their ability to release fluoride for a long time. While this combination of good aesthetics and fluoride release may seem to give compomers an advantage, their poor mechanical properties limit their use. The main components of the compomers are polymerizable dimethacrylate resins, such as urethane dimetha-crylate and TCB (a butantetracarboxylic acid reaction product) and hydroxyethyl methacrylate and ionizable glass fillers, such as fluorosilicate glass.

Otitis and middle ear disease present high morbidity rates in spite of current medical treatment, especially in the younger population. Otitis media with effusion (OME) is a chronic disease that is often found in school age children. Its evolution, recurrence, complications and resolution still present a challenge to otologists. For some time, middle ear ventilation tubes were used for this pathology, thus assuring proper middle ear ventilation and higher disease resolution rates. In the current paper, we investigate the connection between ventilation tube usage, the materials out of which they are made, the techniques involved and how these factors may influence disease resolution rates.

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.