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The paper presents the application of 3D printing in the forensic field in order to perform facial reconstruction on a 3D printed replica of the victim’s skull. Firstly, imagine data from a computed tomography of a skull was converted into a 3D model. Then, the 3D skull model was sliced and printed in different positions in order to optimize the 3D printing configuration. Since the quality of the 3D printing process depends on the thermal and rheological properties of the 3D printing filaments, the rheological behavior of the ABS was investigated using melt flow rate and capillary rheometry. Lastly, an accurate skull replica was achieved using the optimal printing parameters. The 3D printed skull was used to perform the facial reconstruction of the victim by the forensic team. Based on the results of the present research, the 3D printing technology is a feasible solution to obtain anatomically accurate skull replicas.

In the endeavor to explore more and more materials, this work is focused on the study of the potential applicability of a chelating sorbent based on an acrylic copolymer functionalized with amidoethylenamine groups in Cu(II) removal from wastewaters in batch and dynamic conditions. The proposed sorbent was synthesized by the chemical transformation reaction of ethylacrylate (EA): acrylonitrile (AN):2% divinylbenzene (DVB) copolymer with ethylenediamine (EDA). Batch sorption results pointed out that the Cu(II) retention by the acrylic copolymer functionalized with amidoethylen-amine groups was dependent on the initial solution pH, initial metal concentration and contact time. The sorption of Cu (II) on the tested chelating copolymer obeyed both Langmuir and Freundlich isotherms. The Langmuir maximum sorption capacity was 65.21mg Cu (II)/g of polymer. The kinetic experimental data fitted well with the pseudo - second order model. The dynamic behavior of a fixed bed column filled with the acrylic copolymer functionalized with amidoethylenamine groups has been studied in terms of breakthrough curve. The experimental breakthrough data have been well described by Thomas model. The tested chelating copolymer is suitable for multiple processes of Cu(II) sorption-desorption. The column studies with real wastewater sample presented a removal efficiency of 100% for Cu (II) and a significant improvement of the wastewater quality. The acrylic copolymer functionalized with amidoethyleneamine groups can be successfuly applied for the Cu (II) removal - recovery - recycling.

The preparation of polyether polyols from waste rigid polyurethane foam has been achieved by chemical degradation of ethylene glycol and diethylene glycol as the degradation agent. Then, the modified rigid polyurethane foam was prepared by polyether polyols and glass fiber. To detect the characteristic of rigid polyurethane foam, the density, water absorption, compressive strength, thermal conductivity, infrared spectrum, morphology structure had been tested. Finally, the best degradation formula was explored, and the modified rigid polyurethane foam had been prepared from the recycled polyol.

Posterior endodontically treated teeth are exposed to risk fracture due to the great masticatory forces developed in the area. Fiberglass posts are considered a practical solution for such situations, but their main disadvantage yet remains the poor adhesion to the remaining tooth structures. The purpose of the present study was to evaluate a material that could replace the use of fiberglass posts on posterior teeth. 32 premolars were selected and divided into 4 groups (n=8): the first group was considered the control group; the second group was composed of endodontically treated teeth that were filled with gutta-percha, but without any coronal restoration; the third group was composed of teeth that received the same endodontic treatment as in the second group but were restored with a fibreglass post and a light cured microfilled hybrid composite material; the fourth group was similar to the third one, except teeth were restored with a short-fibre-reinforced composite (EverX Posterior, GC Europe N.V., Leuven, Belgium) and a microfilled hybrid composite over it. The fracture resistance of all the teeth was tested using a universal testing device. One-way ANOVA and the Tukey post-hoc variation tests for multiple comparisons were used to analyze the results. The short-fibre-reinforced composite material increased the fracture resistance of endodontically treated teeth (1159.42 N), twice as much as that obtained by using fiberglass posts (522.35 N)). Within the limitations of the present study, EverX Posterior represents a better alternative compared to fiberglass posts in the crown and root reconstruction of posterior endodontically treated teeth.

Despite the advantages of the non-flammable, good performance and low price, poly (vinyl chloride) (PVC) still suffer from poor thermal stability, restricting its melting process and applications. Although addition of some heat stabilizers can be used to improve the low thermal stability, so far, they normally compromise the environmental issues and smoke density of PVC during combustion. In this work, a series of La doping Mg-Al layered double hydroxides (LaLDHs) with different molar ratio of La3+ / Al3+ were successfully synthesized by coprecipitation-hydrothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), Scanning Electron Microscopy (SEM) and Transmission electron microscopy (TEM). The results showed that the as-prepared LaLDHs exhibit plate-like morphology with a lateral size around 100-180 nm. The different as-prepared LaLDHs were introduced into PVC as heat stabilizer to prepare PVC nanocomposites. The thermal stability and smoke suppression of PVC nanocomposites were investigated by TGA, thermal aging, Congo red and smoke density rating test (SDR), respectively. All the results demonstrated that PVC-LaLDHs2 nanocomposites containing 2% LaLDHs2 (the molar ratio of La3+ / Al3+ is 1 / 3) were optimized, which achieved the maximal T50% value of 337.2 oC, minimal SDR value of 45.6%, and prolonged the thermal aging time from less than 10mins to 90mins, respectively thermal stability time from 1242s to 2751s. In addition, the tensile strength and elastic modulus of PVC-LaLDHs2 respectively increased by 84.4% (56.6 MPa) and 75.5% (1019.4 MPa) with little affecting elongation at break of PVC. LDHs (layered double hydroxides); rare earth ions; thermal stability; smoke suppression; poly (vinyl chloride)

Hybrid composites of in-situ microfibrillar recycled polyethylene terephthalate (rPET)/glass fiber (GF)/polypropylene (PP) were developed as an economical and environmentally friendly alternative to glass fiber reinforced thermoplastic PP composites. The effect of replacing glass fibers with in-situ formed polymer microfibrils on mechanical and viscoelastic properties of the composites was investigated with tensile, flexural, and dynamic mechanical tests. Characterization results showed that mechanical and viscoelastic performance of 34% glass fiber reinforced PP can be obtained with 24% glass fiber, 10% microfibrillar rPET composites. Compatibilization effect of the maleic anhydride grafted PP (MA-g-PP) was studied using Fourier transform infrared (FTIR) spectroscopy. The scanning electron microscopy (SEM) images confirmed the formation of the rPET microfibrils in the hybrid matrix. Besides, composites with MA-g-PP compatibilizers showed significantly improved fiber-matrix interfacial adhesion on the SEM images.

The study performed the biomechanical testing of polymethylmethacrylate (PMMA) specimens with unreinforced progressive antibiotic loading, compared to samples reinforced with Kirschner wires, by subjecting these specimens to mechanical compression forces. A difference was observed in the yield of the reinforced specimens with Kirschner wires, in which an antibiotic concentration that exceeded the usual amount was used. In this antibiotic combination of vancomycin powder and liquid gentamicin, the spacer seemed to have a superior structure compared to using only the antibiotic in liquid form. These results are superior to the usually loaded specimens (not exceeding the threshold of 4 g of antibiotic per 40 g of cement), the maximum force recorded being of 20.98 kN and the minimum of 11.54 kN. The reinforced specimens indicated higher values of force, registering differences that varied between 10 kN and approximately 19 kN, thus considering that through the reinforcement with Kirschner wires, the biomechanical qualities of the cement spacers considerably improved.

The study is highlighting the possibility of modeling the properties of composite materials based on recycled polypropylene (PPR), flour feathers(FF), and compatibilizers (C). The composite materials with 10% and 20% feather flour content were mixed and processed with a two-stage extruder having four heating zones between 200-230°C, in order to obtain granules. The granules were injected in various forms to evaluate the properties. The composite materials have been evaluated for determination of melt flow index (1900C; 2.16kg), density, Charpy impact, breaking strength, elongation at break, and the dielectric behavior. The results showed that the introduction of feather flour in the polymer matrix based on PPR leads to decreased flow properties as well as physical and mechanical properties. The solution in solving these deficiencies was to use compatibility agents, that would improve these properties. The physico mechanical properties were analyzed in order to identify a composite with optimal properties for industrial application.

The goal of the research is to develop an experimental mathematical model of pan coating process effect on the biodegradable polymer and to determine optimal process parameters. The polymer solution was conducted with phosphated di-starch phosphate, polyvinyl alcohol, and polyacrylic acid and performed as material coating for the controlled-release urea fertilizer. The image analysis method has been used to determine the particle size distribution, Sauter mean diameter of the particle and layer thickness that is novel. The central composite rotatable design has been selected to determine the regression models of the process, which described the relationship between two objective variables as layer thickness, release time with angle of pan, spray flow, and coating time. The statistical analysis results indicate the fitness of model.

The Additive Manufacturing (AM) industry has expanded steadily, occupying the market very quickly. New types of 3D printers have appeared and new types of polymeric and composite materials have been developed for these printers. Thus it passed very quickly from the stage in which the parts that were made by rapid prototyping (RP) only to be exposed (demonstration parts) to stage AM the parts are fully functional. Of course, the future of AM is still on the horizon, it is barely visible. The other technologies for forming the geometry of the part, ie subtractive manufacturing technology and formative manufacturing technology are still the basis of industrial production. Each technology has its own advantages and disadvantages and is chosen on a case-by-case basis, depending on the objectives pursued. In this paper, a study is made on the rapid prototyping of a single pump rotor part. The material of the piece is of polymer type, ABS. The piece was made in two variants: by additive manufacturing technology (PolyJet) and by subtractive manufacturing technology (milling). After processing, several parameters were followed, such as the functionality of the part, the surface quality, the mechanical tensile strength, the dimensional accuracy, and last but not least the manufacturing cost and the duration of the manufacturing cycle. The data thus obtained were processed with an artificial intelligence program for decision making.