Browse Articles

The work is part of a larger study, representing second note, being focused on the correlation between the behaviour of polymeric materials as such or as copolymers from the group of methyl methacrylate, maleic anhydride and silicone rubber, reinforced or not with polyethylene fiber and metallic copper mesh with antifungal activity for 12 matrix polymer systems used in removable prosthesis and the final, respectively. Keywords: silicone and acrylic resin, maleic anhydride, removable prosthesis, traction resistance, modulus of elasticity, Poisson’s coefficient, fungal activity

Failure of progressive cavity pumps used in oil extraction is mainly due to damage of the elastomer subjected to time-varying load cycles and intensive processes of degradation by abrasive wear. In order to increase the lifetime of progressive cavity pumps is very important to not degrade the elastomer under the influence of operating conditions and working environment. The present paper has the main objective to study the fatigue behaviour of three type of elastomers used for progressive cavity pumps manufacture. Keywords: variable load cycles, progressive cavity pump, elastomer

Viscosupplementation (intra-articular supplementation of hyaluronic acid - HA) provides a useful alternative in treating osteo-arthritis patients and it is included in the professional guidelines for treatment of the disease in knee joint. Rheological investigations add an important element to viscosupplements characterization. In order to improve the hyaluronic acid concentration in currently commercial viscoelastic solution but also for targeted release on the clinical needs, we propose to use the magnetic nanoparticles functionalized with hyaluronic acid. In this paper, we analyze the rheological properties of some experimental viscoelastic solutions obtained after the modification of the commercial viscoelastic solution with a concentration of 40 mg/2mL HA (Arthrum) using different concentration of functionalized magnetic nanoparticles, using a Paar – Physica MC 301 Rheometer. The results indicate improved viscoelastic properties with increased HA concentration. Solutions with lower viscosity are much less effective in converting mechanical energy into elastic deformation and the effect being more visible with time. Keywords: sodium hyaluronate, concentration, ferromagnetic nanoparticles, rheology

Effects of Quantitative Changes on Drinking Water Quality Indicators of Urban Distribution Networks ION MIREL1, CONSTANTIN FLORESCU1, ALINA GIRBACIU1, CRISTIAN GIRBACIU1, PAVEL DUMITRU1, SORIN DAN2, RAMONA AMINA POPOVICI3*, GEORGE-LUCIAN IONESCU4 1 Politehnica University of Timiºoara, Civil Engineering Faculty, Hydrotechnical Engineering Department, 1A George Enescu Str., 300022, Timiºoara, Romania 2 Politehnica University of Timiºoara, Civil Engineering Faculty, Civil Engineering and Building Services Engineering Department, 2 Traian Lalescu Str., 300223, Timiºoara, Romania 3 “Victor Babes” University of Medine and Pharmacy Timisoara, 2 Eftimie Murgu Sq., 300041, Timisoara, Romania 4 University of Oradea, Faculty of Constructions and Architecture, 4 Barbu Stefanescu Delavrancea Str., 410058, Oradea, Romania In this paper are shown quantitative and qualitative changes in the drinking water distribution system, occurring in an urban locality with about 200 000 inhabitants in which water consumption over the past decade have been reduced by 50%. In relation to consumer debts are highlighted oscillations related to water pressure in the system and residual chlorine concentration on pressure zones. Hydraulic modeling of the water distribution system was performed using computer programming software, EPANET type, program that performs hydraulic simulations and water quality in pressure pipeline network. After analyzing and interpreting the results of hydraulic simulations performed in different operational situations (consumption 100; 75; 50%) resulted in areas where residual chlorine levels fall well below the limits imposed by the laws and regulations in force. In this situation are required corrective measures on water quality by reducing or eliminating water stagnation by increasing the velocity of the water circulation pipe sections affected. The book is useful for units or operators that use water networks in areas with significant debt fluctuations where by reducing travel speeds on sections of pipeline in areas where residual chlorine drops below the limits, favoring the formation of ecosystems biological and thereby triggering internal processes of auto-pollution reflected in the degradation of water supplied to consumers. Keywords: disinfection, residual chlorine, stagnation, water demand, pressure

In-homogeneity, anisotropy, abrasiveness, and low thermal conductivity of glass fibre-reinforced polymeric composites make their machining more difficult as compared to metals. This fact explains numerous machinability studies that were carried out for some of these materials. The experiments presented in this paper were devised to assess the machinability in drilling process of a Romanian made glass fibre-reinforced polymeric composite. Keywords: polymeric composites, machinability, drilling

A post-mortem examination of an 8 years old German Shepherd dog was performed in order to find out the death cause. The macroscopically examination revealed a large amount of blood in the abdominal (hemoperitoneum) and pericardial cavity (hemopericardium) and also the rupture of the right atrium. The spleen was sampled for histopathological examination. Hematoxylin-eosin–methylene blue staining was performed in order to prepare the samples for microscopical examination. Based on the specific histopathological changes and taking into account all the pathological data, the diagnosis was hemangiosarcoma. Key words: hemangiosarcoma, German Shepherd dog, hematoxylin-eosin–methylene blue staining

The study compares the environmental impacts of 500 mL water bottles produced from corn-based polylactide (PLA) and PET. The results of cradle-to-bottle factory gate assessment revealed that the usage of PLA granules instead of PET granules would reduce the net global warming potential and cumulative nonrenewable energy demand of bottles by 30.9% and 32%, respectively. However, if no credits are given for atmospheric CO2 fixed by corn, and the energy in corn-feedstock is accounted for, the advantages of PLA would be largely diminished. Keywords: polylactide, PET, bottles, life cycle assessment

Orthodontic treatment with the clear plastic aligner is becoming one of the most popular treatment options among adults and teenagers. The high precision of the virtual planning of the case leads to well fitted thermoformed plastic aligners and an individualized treatment for each patient. Several cases were treated with Clear Aligner therapy. All treatment outcomes were previsualized with the digital OrthoAnalyzer CAD software (3Shape) in order to design specific appliances for specific dental movements, with a lower risk of root resorption or other secondary effects. All desired dental movements can be measured and then transposed into a series of amorphous plastic aligners. Patient compliance and communication with the dental laboratory are enhanced due to the continuous developing of the CAD/CAM technology and Clear Aligner system. Keywords: digital setup, OrthoAnalyzer, plastic aligners

The paper presents, from a comparative point of view, methods to increase the controllability of a drone. An important step in increasing the controllability is using light weight and resistant materials for the rotating parts of the drone. Also, the controllability can be increased by studying the structure of the propeller in order to reduce its moment of inertia. Keywords: drone, moment of inertia, propeller, controllability, carbon fibre

The prediction of polymer properties, based on its composition, it is a complex problem with no easy method to obtain directly and accurately results. Among the tribological properties, the friction coefficient and wear rate are the most interesting ones. The polymers based on epoxy resin, with clay as filler, show different properties depending on the clay concentration. This paper presents an analysis of the polymer properties variation with its filler concentration. Due to the tribological processes complexity, mechanical and thermal properties must be taken into account. The aim of this study is to find an optimal concentration value, with minimal influence on polymer properties, using neural network models. All value properties were used in order to optimize and predict the composite properties. Keywords: polymer properties, tribology, filler concentration, neural network, prediction