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The change of the organic bone cements’composition (COO) determines the adjustment of some important properties for the behaviour as fixing material, such as the: superficial tension, polarity, surface energy, viscosity, contraction at polymerisation, porosity. In the present paper we monitored the influence of the composition’s changes for some acrylic cements upon their handling features. The samples were obtained via the partial replacement of the methyl methacrylate (MMA) in the liquid phase of some usual formulas with another acrylic monomer. For these, it was measured the contact angles as wettablility of the fixing material. Moreover, it was estimated the values of the hardening time, important parameter for the application phases of the cements with cold hardening and fixing of the articular endoprostheses.

The purpose of this experimental laboratory work is to obtain composite membranes having carbon and gold nanoparticles in the matrix. Consideration was made of using graphene oxide, a material which, under certain conditions, can generate membranes by a self-assembly process under vacuum in an aqueous or organic medium. The cellulose acetate (CA) - graphene oxide (GO) composite membranes have been functionalized with gold nanoparticles (AuNP) by two technological processes: thermal evaporation and ultrasonic mixing of stable graphene oxide and gold suspensions. The stable suspensions containing gold nanoparticles were obtained by chemical reduction of aqueous solutions of Tetrachloroauric acid trihydrate (HAuCl4) precursors with sodium citrate under high temperature conditions. Dispersibility of carbon nanostructures and precious metal nanoparticles has been studied with a DLS granulometer - Malvern Instruments Zetasizer ZS90. It was determined the mean particle size and Zeta potential function of the suspensions pH. The graphite based membranes were further subjected to various characterizations techniques. It was found that both the surfaces and the cross-sections were functionalized with gold particles. The presence of Au particles was revealed both on the membrane surface and also inside its structure. Hydrophilic tests demonstrate that the membrane filters have potential to be used in various applications.

A facile and inexpensive approach was established to prepare spherical molecularly imprinted polymers with hypericin (H-MIPs) via the wet-phase inversion method. The H-MIPs were characterized by infrared spectroscopy and thermogravimetric analysis. High-performance liquid chromatography combined with UV–Visible spectroscopy were used to assess the efficiency of the extraction procedure and, furthermore, to investigate the recognition properties of the H-MIPs. Obtaining an imprinting factor of 3.38 for hypericin strongly indicated a successful formation of molecularly imprinted cavities onto the H-MIPs. A fair selectivity towards hypericin was tested in comparison to the interfering molecule pseudohypericin.

Propolis is a natural apicultural product derived from plant resins with impressive health benefits. Its major biologically active substances are barely soluble in water, but this could be increased by proper formulations.The aim of the present study was to obtain a transmembrane delivery system based on polyurethane microstructures for eight propolis samples collected from different regions of Western Romania and to characterize them by differential scanning calorimetry (DSC); the assessed parameters were the particle size, the polydispersity index and their clustering tendency. Polyurethane polymers based on isophorone-diisocyanate and polyethylene glycol 200/ethylene glycol were chosen as carriers for the propolis extract. A perfect inclusion of propolis inside the structures was observed for half of the samples. Particle size ranged between 504 and 621 nm and was confirmed by the low stability against aggregation (Zeta potential: 16.3-19.8 mV). The polydispersity index was between 0.4 and 0.7.

The new generation of newly developed materials, namely the high-crystallinity and high temperature polypropylene random copolymer, called PP-RCT, increases the crystalline capability of polypropylene, which allows pipes produced from this material to operate at higher pressures at elevated temperatures. Pressure tests on pipes made of PP-RCT materials show a resistance over a period of 50 years at 7000C (1580 F) 5 MPa (725 psi) compared with 3.2 MPa (464 psi) for standard materials PPR. By reinforcing PP-RCT with aluminum, glass and basalt composite results in a more resistant structure. As a result of the traction tests, it was found that in all three samples the tensile strength exceeds the manufacturer s limit (10 - 12.7 MPa), the values obtained being: st1 = 8 MPa - sample no. 1; st2 = 13 MPa - sample no. 2; st1 = 11 MPa - sample no. 3. The fiber glass insert is less resistant, the best variant being the basal insect sample (st2 = 13 MPa). Elongation at break for specimen no. 3 was recorded at 0.027 mm / mm. Tests on these material combinations were performed for stretching and flexing requests and compared to 3D created virtual models. Simulations of internal pressure behavior were also performed for different material configurations and the results were compared with the experimental data and the data supplied by the manufacturers.

This paper shows the ageing study of some coatings and / or impregnation lacquers due to microbiological stress through fungal attack. Dielectric spectroscopy has shown that the dielectric losses of the investigated materials increase as result of microbiological ageing. The mean recorded increases are about 4 times for the alkyl-epoxy-melamine copolymer, 2 times for epoxy polymer and 1.5 times for urethane polymer in agreement with the mould coverage degree of about 20 %, 10 %, and 3 %, respectively. The fungal attack of the investigated polymers led to a decrease in volume resistivity of about 65 % for the alkyl-epoxy-melamine copolymer, 45 % for the epoxy polymer, and 14 % for polyurethane, in agreement with the increase of dielectric losses and degree of mold coverage of the samples. FTIR determinations have shown that fungal attack significantly increased the number of aliphatic -OH and C-H bonds and decreased the number of C–O bonds, respectively of C–O–C oxiran groups and C-C aromatic bonds. DSC thermograms recorded at different temperature ranges and the activation energies calculation for first major oxidation process indicate that after the fungal attack the thermooxidative reactivity of the investigated polymers increases.

PLGA (Poli-lactic-co-glycolic acid) nanoparticles (NPs) are curently used as drug delivery systems for many types of drugs including antioxidants such as vitamin E. The main aim of our study was to test the antioxidant effects of PLGA-vitamin E on Wistar male rats. Two groups of Wistar rats received a hypercaloric diet for 21 days: the first group received besides the hypercaloric diet a daily dose of PLGA loaded with vitamin E and the control group received only the hypercaloric diet. Spleen cellular lysate has been used to detect biomarkers of oxidative stress such as malondialdehyde, glutathione, advanced human oxidative protein and vitamin E. After 3 weeks of treatment, statistical significant changes have been detected between the two groups.

The aim of this study was to evaluate the efficiency in using intermaxillary elastics to stimulate mandibular growth and advancement in orthodontic patients diagnosed with skeletal Class II malocclusion as well as to compare the use of these Class II elastics in two different therapeutic approaches. The sample consisted of 60 orthodontic patients aged 10-15 years, 34 girls and 26 boys. The sample was divided into two equal groups (each consisting of 30 patients). Patients belonging to the first group (Group 1) were subjected to 1/4¹¹ - 6.0 oz elastics and were advised to change the elastic every 24 hours. Patients belonging to the second group (Group 2) were subjected to 1/4”- 4.5 oz elastics but with a recommendation to change the elastics every 12 hours. In order to evaluate the effectiveness of these two types of Class II elastics on mandibular growth and advancement, the value of the SNB angle at the beginning of the treatment (T1) was compared with the value of the SNB angle after 5 months of wearing intermaxillary elastics (T2). All patients showed statistically significant increased values of the SNB angle during the orthodontic treatment (p[0.001). Patients in Group 2 showed a significantly higher statistical increase (p[0.05) than patients in Group 1.

The enterprise has an intricate and elaborate system of relationships between the departments, functioning closely as a cell within an organism, with its defined role within the market. In the complex context of actual economic system, resources are limited and enterprises seek for efficiency in order to reduce costs. In this paper we present the development of a solution for the optimization of an agricultural enterprise related to the plastic-based materials usage in the agricultural processes. In this matter, the experimental part consists in the creation of a model of a plastic management system using methodologies from the literature (e. g., System Dynamics or SD etc.) and its simulation with specific tools used traditionally. Besides the experimental part, we will make a short analysis regarding the structural and economic issues regarding plastics used in agriculture and some considerations regarding the bioplastic material that can be obtained from different types of agricultural waste.

It was found that the obtaining of quality 3D printing filaments, without defects and natural color, from corn starch physical modified with PVOH, depends also on the melting behavior at compounding, both of starch and of PVOH, and on the controlling of the process sensitivity of the new compounds. A comparable melting behavior was possible by compounding the two polymers as powders with similar small sized particle. The controlling of the process sensitivity was achievable, mainly, by diminishing the melt resistance to flow, via formulation with a flow agent. The selected compounds which had controlled miscibility, few defects and natural color were shaped, with good results, as filaments with silky and smooth surface. These filaments were compatible with 3D printing because proved to have the ovality and the diameter tolerance in the accepted limits in the fields.