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Consolidation of old frail wood by impregnation with polymers is a key step in wooden cultural heritage conservation. Paraloid B72 is an acrylic polymer widely used for this purpose. FTIR spectroscopy, though microdestructive, was found to be a versatile method able to reveal the presence / penetration of Paraloid B72 into the wood structure. A semiquantitative method of investigation was developed with the aim of correlating FTIR data with gravimetric analysis. Relative consolidant retention indexes were calculated based on the integrated areas of relevant absorption bands and compared with gravimetric data of consolidant retention, resulting a fairly good correlation. The method developed on laboratory treated samples made of new sound wood (poplar Populus tremula) was further applied on three case studies, representing heavily degraded wooden artefacts from cultural heritage. Keywords: Paraloid B72, wood consolidation, FTIR, cultural heritage

Dental restorative materials due to their composition and structure relatively easily reacts in oral environment, subject to a chemical, electrochemical and biological degradation process. Effects vary from material discoloration and pigmentation, leading to cracks or fractures of fillings. Saliva as oral biotope is a continuous environment favouring these changes. In this saliva are dissolved chemicals coming from the external environment (food, beverages), which modifies the composition and the pH of the saliva, elements which are playing a main role inside the degradation processes, and in particular in electrochemical process. The intensity and its effects are heavily determined both by the composition, structure and quality of materials used and the composition and pH of saliva. Keywords: composite materials, restorative dentistry, artifcial saliva

This is a study between ultra-high molecular weight polyethylene (UHMWPE) reinforced with zinc oxide (ZnO) under various filler loadings. These composites were then incorporated with chitosan for hybridization purposes. All composite specimens were prepared by using a hot compression mold through dry ball milling process. Wear and tensile tests were carried out using specific experimental techniques namely pin on disc method as well as universal testing machine, respectively. Results indicated that the addition of ZnO filler up to optimum percentage (12 wt%) has significantly increase the wear resistance of tested composites, in accordance with the minimal weight loss. Contrary, the incorporation of chitosan (1, 2, 3 wt%) in the optimum percentage (12 wt%) of UHMWPE/ZnO composites has slightly reduced the wear resistance of the hybrid composites. For the tensile properties point of view, the results indicated that the yield strength, tensile strength and Young modulus were perpendicularly increased with increasing of ZnO filler loading, up to 12 wt%. Meanwhile, the elongation at break show contradict trend where it was gradually decreased with an increasing ZnO particle loadings. Interestingly, the incorporation of 2 wt% of chitosan in the optimum percentage (12 wt%) of UHMWPE/ZnO composites has further increased the yield strength as well as the elongation at break values of tested hybrid composites. Ultimately, the morphology analysis was also carried out in order to visually justify the state of hybridization and dispersion of fillers within UHMWPE matrix. Keywords: ultra-high molecular weight polyethylene (UHMWPE), hybrid filler, wear resistance, tensile properties, morphology analysis

The emergence of self reinforced polymers relaunched the osteosynthesis with resorbable materials, especially in the case of the long bone ends fractures. The improved mechanical resistance and the slow resorbtion are the main advantages compared with previous generations of bioresorbable materials. These qualities prompted us to conduct this study, which focuses on assessing the strength of new implants made of self reinforced polylactic acid (SR-PLA). The implants are designed for osteosynthesis of transcondylar fractures, one of the most common types of distal humerus fractures. Our innovation in terms of implants is to amend a malleolar bone screw so that it can be locked with a Kirschner wire or a thin screw. Thus, an assembly consisting of two screws of this type and a locking wire significantly increases the contact surface between the fragile epiphyseal bone and the implant. The study uses the finite element method and simulates the postoperative loading conditions of the bone-implant assembly. Two CAD models were created representing a stable and an unstable fracture fixed with these implants having the properties of SR-PLA. The models were imported, edited and analyzed in a state of the art finite element program. The evaluation of the interfragmentary displacements, normal stresses in bone and equivalent stresses in implants shows that the osteosynthesis of the stable fracture successfully bears the loads imposed on the entire arc of flexion-extension, while the unstable fracture fixation is fragile at the extremes of the range of motion. The weak point of both assemblies is the metaphyseal cancellous bone. For both models the screws made of SR-PLA held up very well in the given circumstances: the equivalent stresses were low relative to material mechanical resistance. SR-PLA appears as a suitable material for this type of osteosynthesis, but additional biomechanical studies are needed to confirm these results. Keywords: self-reinforced polylactic acid, transcondylar fracture, finite element analysis

The paper present the experimental results of a comparative research study between classical and ultrasonically processing by extrusion of the HDPE-220J (High Density Polyethylene) polymeric material. For this material, often used in engineering, have been obtained, in flow activated using ultrasonic waves, relatives increases of the flow rate up to 77% of polymer flowing through extrusion compared with the processing without ultrasounds. These results have been obtained in laminar flowing and no imperfections have been presented due to the extrusion process. The experimental results of the state transition using the differential scanning calorimetry analysis DSC (Differential Scanning Calorimeter), realized for classical and ultrasonically flow activation, confirms that ultrasonic microvibrations produced no changes in the internal structure of the polymer. The ultrasonic device used in this research is subject to a patent application registered at OSIM with number A/00979/2013. Keywords: polymeric materials, extrusion, ultrasounds, flow rate

The work is dedicated to the study of the tensile properties of the seven layers of materials which compose the firemen protective clothing. Protective clothing is used to improve the working place safety, diminishing the action of risk factors, which can be of thermal, chemical, biological, mechanical, physical or electric nature and have direct influence on the life and health of the person who carries out a certain activity. The basic material used in manufacturing these products must possess special characteristics, thus ensuring the accomplishment of certain activities which imply the existence of risk factors. The studied firemen equipment has in its composition NOMEX and KEVLAR technical yarns. The analysis of textile material behaviour in the wearing process shows that these are subject to simple or repeated uniaxial or biaxial tensile stresses. The level of these stresses can be close to breaking strength or it can have small, insignificant values; therefore the designer must anticipate the behaviour to such stresses, and this can be done by determining the indices inferred from the stress - strain diagram. Keywords: protection equipment, stress-strain curve, risk factors, Kevlar, Nomex

This paper analyses the influence of the grind percentage on some mechanical properties, obtained by the injection of different technical items, which are made of polyamide 6.6 Grivory HTV-3H1 noir 9205, polyamide 6.6 Grivory HTV-45H1 noir 9205 and polyamide 6.6 Grivory HTV-6H1 noir 9205. The specimens are made of the following compositions: new material 100%, new material 80% + grind 20%, new material 60% + grind 40%, new material 40% + grind 60%, new material 20% + grind 80% and grind 100%. The mechanical properties were measured using tensile tests, the Izod impact test and the Shore Durometer hardness test. It has been observed that the hardness of the three tested polymers is hardly influenced by the increase in grind percentage. The shock resistance decreases along with the increase in the grind percentage, and the tensile strength at break increases along with the increase in the grind percentage. Keywords: polyamide 6.6 (PA 6.6), tensile tests, the Izod impact test, the Shore Durometer hardness test

Acrylic resin materials are used for making dentures, artificial teeth, veneers, crowns, and temporary crowns, etc. The surface structure of acrylic resins as well as composite resin and ceramic are a favourable environment to the bacterial plaque development. Researches from domain lead to more qualitative acrylic resin and polymers: diacrylic composite resins, epoxide resins, etc. Diacrylic composite resins have superior mechanical and aesthetic properties but are inferior to ceramics. The prosthetic restorations and the presence of different materials in the oral cavity represent a proper environment for the development of microbial flora. The oral cavity health depends on correct prosthetic treatments and a balanced microbial flora that can be controlled with bacteriostatic substances, oral hygiene and correct prosthetic restorations. Bacteriostatic effect of silver nano-particles over plastic dental materials may influence and contribute to the activity of bacterial micro-flora and may influence the evolution of periodontal disease and gingivitis by destroying the dental plaque. Key words: acrylic resin, diacrylic composite resins, crowns, silver nano-particles

During endodontic therapy, an important effect of the reparative materials used is to induce periapical recovery and stimulation of osteogenesis. The study aimed to assess the dynamics of alkaline phosphatase levels measured at different time intervals and was conducted by implanting three biomaterials in the rabbit subcutaneous connective tissue, next to the bone. The biomaterials used were: MTA (Mineral Trioxide Aggregate, Dentsply, Tulsa Dental, U.S.A.), Sealapex (Kerr, Switzerland), and DiaRoot Bioaggregate (Inovatore BioCaramixInc, Vancouver, BC, Canada). This study was focused on a quantitative analysis, based on biochemical examination. Keywords: alkaline phosphatase, osteogenesis, biomaterials, endodontic treatment, stomatognathic system homeostatis

The purpose of this study was to analyze the interfacial morphology between dentin and a single-component dental adhesive system (Single Bond Universal, 3M ESPE), applied with or without preliminary phosphoric acid etching. In this study, 20 cavities were prepared in extracted teeth and restored with composite resin, using the tested adhesive. The axial sections were observed by scanning electron microscopy. When the adhesive was applied without etching, the hybrid layer was thin and not uniform. The resin tags could rarely be observed within the tubules. Preliminary acid etching of dentin resulted in thicker hybrid layers and augmented resin tags. However, for the tested adhesive, preliminary etching with phosphoric acid did not seem to significantly improve the quality of the dentin sealing. The EDX determination using the Line mode of the elements variation indicated a more severe drop of calcium in dentin when preliminary etching with phosphoric acid was applied comparing to the situations when the adhesive was applied in self-etching procedures. Keywords: bonding system, phosphoric acid, hybrid layer, dentin, self-etch, total-etch