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This paper is the first note on experimental protocol development regarding the use of Iosipescu test specimens with acrylic fibre insertion or without the insertion, with metal or textile fibres in a series of tests in which the structural and constructive characteristics of matrix biomaterials are optimised for removable prosthetic restoration. Tensile and shear tests allowed the determination of specimen consolidation with aluminium plates of clamping jaw heads. Based on the theoretical protocol, the following were determined: shape, size and loading of Iosipescu specimen and deck sizing. The CT-1 silicone adhesive behaviour was evaluated based on experimental data. Poly (methyl methacrylate), denoted as PMMA, was used in the study. PMMA has polyethylene fibre and copper wire mesh inserts. These were individually assembled using this adhesive that was used to fix aluminium plates on the clamping jaw heads. The values obtained for the maximum normal traction stress, smax ranged between 22 and 60 MPa, and the tangential shearing stress tmax, of the adhesive ranged between 2 and 6 MPa, with an average value of 4.75 MPa, both depending on the dimensional characteristics and structural composition of the specimens, thus confirming the role of stratification and inserts in the mechanical strength of the specimens. Stress values of smax and tmax allowed the determination of the dimensions of the surface the specimen clamping jaws are fixed upon, practical aspect influencing the accuracy of the final results. Keywords: Iosipescu test, silicon resin, poly (methyl methacrylate), removable prostheses

The goal of this study was to measure and analyze the water sorption and mechanical properties of 5 experimental flowable composites with different filling ratios and two types of initiation systems: self cured and light-cured. The samples were analysed, in order to observe the influence of initiation type and the amount of filler on the properties required to satisfy the conditions for dentistry use. We have determined the water sorption and mechanical properties (compressive strength, flexural strength, diametral tensile strength) according to ISO 4049/2000 and international norms “American Dental Association’s Specification No.27. The measurements were done using a mechanical testing machine Lloyd Instruments-LR5k Plus. Increased water absorption weakens the bonds in the polymer matrix, causing separation of filler by the polymer matrix, filler hydrolytically degrade, leading ultimately to reducing the mechanical resistance, which represents a major step in the characterization of dental materials to be used in dentistry. Among all the mechanical stress from oral cavity, the compression and the tension are the predominant forces, during which are developing the highest forces that dental hard tissues are subject to. The results of this study highlight the relationship between the composition, initiation system of the dental materials and their properties. Keywords: flowable dental composites, water sorption, compressive strength, flexural stiffness, tensile strength

IOL opacification is a growing issue reported lately in the speciality literature. [1-5] This article follows a series of retrospective cases regarding hydrophobic IOLs that were explanted from three different patients. The explants were examined using AFM and SEM (with EDS), in order to find more details about the surface morphology and the composition of the deposits. The results indicate that they are composed mainly of calcium and phosphate. The authors suggest that ocular comorbidity and other systemic factors are contributing to this complication. Keywords: IOL opacification, explanted IOL, surface deposits

The hepatic portal vein (HPV) is the central element of liver afferent pedicle. The intraparenchymal distribution of HPV determines the liver segmentation. The medial branches (MBs) serving left medial division (LMD) of the liver present the greatest morphological variability. On a total of 125 pieces of liver corrosion casts, one examined the intraparenchymal distribution of portal MBs and the segmentation of LMD. Regarding the intraparenchymal distribution of the branches in the LMD of the liver, we showed three distinct morphological types: Type I (81.6% of cases) where are present several small MBs with oblique downward trajectory; Type II (15.2% of cases) that has two distinct MBs, originating in the distal part of the PHV left branch, with slightly upward trajectory; Type III (3.2% of cases) that has three MBs, originating in the distal part of the PHV left branch, the higher with upward trajectory, the lower with downward trajectory, and the middle branch with variable trajectory and originated from the PHV left branch or in one of the first two MBs. Knowledge of this morphological types of portal MBs is important for clinical and surgical practice. Keywords: corrosion casts; hepatic portal vein; medial branches; variability; morphological typologies

The influence of the painting process on a biocompostable waste is studied. Disintegration degree (D %) of a 100% biocompostable plastic made from potato almidon is calculated for both painted and non -painted samples. Solid matrix is also characterized by means of a laboratory scaled composting process following UNE-EN norms [2, 3]. It can be concluded that painting has a negative influence on biocomposting process decreasing 4.48% disintegration degree. Average D% for painted samples is 84.56 %, and 89.04 for non- painted ones. Regarding to solid matrix, dry mass after composting is double (91.12 %) as before process (43.63 %) for painted samples and 91 % and 45.41 % after and before composting for non-painted samples. Volatile solids are reduced 5.17 % after composting for painted samples, and 8.78 % for non-painted. Organic nitrogen is reduced 0.34 % and 0.16% for painted and non-painted samples respectively. The negative effect of painting is mainly due to the barrier effect of the paint that prevents microorganisms from converting organic components of the biopolymer into water, CO2 and compost. Keywords: biodisintegration; composting; painted; bioplastic; waste

In order to investigate the pyrolysis characteristics and mechanism of moso bamboo, its pyrolysis behaviour has been investigated by thermo-gravimetric analysis (TGA), which can be described as four steps: dehydration, hemicellulose pyrolysis, pyrolysis of cellulose and lignin, and residue decomposition. The decomposition of hemicellulose, cellulose and lignin are the main contributions for pyrolysis weight loss. Furthermore, the pyrolysis mechanism has been clarified based on pyrolysis kinetics model fitting. Detailedly, the pyrolysis kinetics of hemicellulose agrees with first order chemical reaction, whereas the pyrolysis kinetic equation of cellulose and lignin accords with the 1D-diffusion parabolic curve. And the apparent activation energy of them is 124.62 and 232.64 KJ/mol, respectively. Keywords: Moso bamboo, pyrolysis characteristics, pyrolysis kinetics, thermo-gravimetric analysis

The paper presents the results of compressive tests performed on Biomet® orthopedic bone cement currently used in arthroplasty. By direct molding of the cement, cylindrical test specimens were manufactured with cross section diameter of 6 mm and height of 12 mm. The stress–strain curves of all specimens tested exhibited similar linear elastic regime with a local maximum followed by yielding. The average compressive strength of the samples is 91.55 MPa, while the average modulus of elasticity was calculated at 1483 MPa. The obtained results can be used in order to asses the fatigue life-time of this type of bone cement. Keywords: total hip replacement, bone cement, PMMA, compression, elastic modulus, Poisson’s ratio

The paper presents a brief overview of the polymeric materials recycling problems and especially those connected with polypropylene reprocessing. It is pointed out the manner in which reprocessing of polymeric materials determines the change of the polymeric melts viscous-elastic properties and, as a consequence, the change of rheological behaviour during the recycling process. It was chosen to do the study of the extrusion reprocessing, so, it was determined, after a significantly number of recycling, the modifying of the process parameters needed in order to obtain the best performances and the highest quality of the product. There were compared the screw extruder performances in the case of the first processing and after ten times recycling of the PP. Keywords: recycling, rheological behavior, polymeric materials, polypropylene, screw extruder

This paper presents the tribological behaviour of four polymeric materials, polybutylene terephthalate (PBT), PBT + 10% micro glass beads, PBT + 10% polytetrafluoroethylene (PTFE) and PBT + 10% aramid fibers, in order to rank them in dry sliding regime. Tests were done using a block-on-ring module. The test parameters were: the sliding speed was set for 0.25 m/s, 0.50 m/s and 0.75 m/s, respectively, the load and the sliding distance being kept constant (5 N and 5000 m, respectively). There were analyzed the dependence of friction coefficient and linear wear rate on the adding material. Particular wear mechanisms were identified with the help of SEM images. Keywords: PBT-based materials, PTFE, glass beads, aramid fibers, friction coefficient, linear wear rate

In this paper we study the influences on mechanical behavior of nonuniformity that appear in bars reinforced with carbon fibers fabric, and respectively carbon-kevlar fibers fabric. We studied the manner in which nonuniformity produced by interruption of a layer or two layers of reinforcement affects the modulus of elasticity, tensile strength and elongation at rupture. In addition to these mechanical properties, we have experimentally determined the coefficient of uniformity for samples with matrix of epoxy resin, reinforced by carbon and carbon-kevlar fibers fabric and which having one and two layers with interruptions. By changing the dimensions of interruptions from layers we analyzed the effect of these nonuniformity on the mechanical properties studied. Keywords: composite materials, uniformity coefficient, elasticity modulus, tensile strength