Volume 55, Issue 3

Abstract: The crystal structure of tetrakis(2,2’-bithiophene-5-yl)silane, C16H10S4Si0.5, has been determined at 293K in the Monoclinic (I2) symmetry. The Si atom has quasi-perfect tetrahedral geometry and bithiophene unit are quasi-planar. Comparison of Si-C bond lengths with literature data indicates an electron donating effect of the terminal thienyl ring on the first C linked to the Si central atom. The study of C-C bond lengths reveals a much more aromatic character for the four thienyl rings directly linked to the Si atom. The molecular packing arrangement shows that each molecule presents eight intermolecular contacts.

Abstract: The paper presents the obtaining of zinc and zinc composite coatings using electrochemical TiO2 nanoparticles as well as the determination of the influence of gelatin used as an additive on electrically co-deposited layers. The obtained coatings were studied at the electronic scanning microscope (SEM) for microstructure observation. A distinction was made between the pure zinc electro-deposed layer and the influence of nano-TiO2 on the morphology of zinc nanocomposite layers Zn/nano-TiO2, as well as the determination of the degree of inclusion of nano particles of TiO2 into the zinc matrix. It was confirmed that with the introduction of nano-TiO2, both the roughness of the electro-deposed layer and the micro hardness of the electro-deposed layer significantly increased compared to the micro hardness of the pure zinc electro-deposed layers confirming the existence and beneficial effects of nano-TiO2 in electro-co-deposed nano-composite layers.

Abstract: The paper focuses on the obtaining of novel nanocomposite hydrogels based on polyacrylamide and layered double hydroxides (LDHs) modified with double bonds. The modification of LDH clay was investigated by FTIR, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses. Mechanical properties of the nanocomposite hydrogels were employed by compression and rheological measurements. The formation of exfoliated and intercalated structures was evidenced in transmission electron microscopy (TEM). Chemical cross-linking of hydrogels using both classical cross-linker and modified clay was an efficient method to improve the mechanical properties of novel nanocomposite hydrogels. These hydrogels with improved mechanical properties could be further tested for biomedical applications such as tissue engineering.

Abstract: The thermal coefficient of linear expansion, the electrical conductivity and dielectric permittivity of fabric reinforced hybrid composites with filled stratified epoxy matrix were investigated. The measurements of electrical conductivity and dielectric permittivity had been performed, using standard method regarding electrical resistance and electrical capacity. In order to point out the effect of filler and of the spatial distribution of reinforcement layers, the medial layer of fabric was especially prepared by introducing copper wires in the woven. So, the medial layer is made of different types of tows (carbon, aramid, glass). This attempt is made in order to design a composite able to provide information about its state during various loading. The results showed that the fillers did not improve the electrical parameters of epoxy matrix, but they led to reduce the thermal coefficient of linear expansion. The thermal and electrical behavior of hybrid composites varied in dependence of number of carbon layers and fiber orientation.

Abstract: In this paper, the potential of using ethylene-vinyl acetate (EVA) filled with multi-wall carbon nanotubes (MWCNT) composites for strain sensing was investigated. Stress relaxation experiments were conducted on injection-molded samples, and the stress and electrical resistance were measured in situ during the relaxation process. Based on the experimental results, it was found that the electrical resistance of the EVA/MWCNT composite increases with increasing strain, and exponentially decreases with relaxation time, indicating the capacitive behavior of MWCNTs. The maximum electrical conductivity of 7.35×10-4 S/cm was obtained for the EVA/MWCNT composite with 5 wt.% at 180°C, whereas higher piezo-resistive sensitivity was obtained for the composite with 3 wt.%. The electrical percolation threshold was found to increase from 0.223 wt.% at 140°C to 0.994 wt.% at 180°C.

Abstract: In this paper we present a comparative study on tensile failure behavior of polymer stiffened composite shell structures, using infrared thermography and finite element analysis through the ABAQUS 6.13 program. The establishment of the distortion of some rectangular shaped specimens was followed. In these specimens a hole with a diameter of 15 mm was applied centrally. By means of infrared thermography, was studied experimentally the variation of the deformations over time, depending on the stress force and the evolution of the thermal field in the crack area. Simulation models of failure behavior have been performed, which have been validated by experimental results.

Abstract: The composite materials with polymeric matrix represent a great realization of chemical engineering. Their applications in all the industrial fields are dictated by their chemical, physical and mechanical properties. In the last 50 years the polymeric composite materials received a large use in the protection and repair work of the surfaces in contact with fluid currents of various natures. The scientific researches followed by the industrial use, show that the polymere films with certain composition and properties have an excellent behavior to chemical, abrasive and cavitation erosions. Because the most stressed machine details subjected to cavitation erosions are the blades, runners and impellers of hydraulic machines as well as the ship propellers, researchers are looking for the best polymers to increase the running time, or for the use in covering the zones with shallow erosions, during the repair work. In this direction is oriented also the present research, performed in the Cavitation Laboratory of the Timisoara Polytechnic University. The obtained cavitation erosion for specimens covered with different polymere films is compared with those realized in identical conditions, but for specimens without protection films. The results show that the films assure some increase in the resistance to cavitation erosion but the tested polymer layers have reduced adherence on the metal surface.

Abstract: Poly lactic-co-glycolic acid (PLGA) is a biodegradable polymer that has been the focus of intense research due to its potential applications in medical research. Its uses in nanotechnology are underlined by its capability of targeting various cells and delivering active compounds to different human tissues. To date, PLGA nanoparticles are employed in areas such as vaccination therapy, diagnostic imaging procedure and various applications in various anticancer therapies. The aim of the present study is to measure and evaluate different correlations between oxidative stress parameters in spleen and liver following administration of nanoparticles encapsulated with lutein in an animal model. Our results show that acute oral administration of PLGA NPs induces a change in the oxidative stress status in both liver and spleen of rats, but does not induce oxidative stress damage to cell structures such as lipids or proteins.

Abstract: The memory shape materials seem to be extremely promising materials for medical applications especially as inserts to support the muscular system. In the case of memory shape polymers a supplementary issue is related to their bio-compatibility such as they can be rejected by the organism even their properties are fitting the requirements. Present study started from the hypothesis that mixing the epoxy resin with other polymers some valuable materials could be obtained especially for energy storage. The epoxy resins possess extraordinary properties (relatively to other thermoset polymers) but they also show an excellent stability that generates problems when this type of materials should be neutralized. Epoxy resins also show low water or other liquids absorption due to their low porosity and they cannot be used for energy storage applications when mobility of charge carriers is ensured by liquid phase. A polymer with high porosity used for membrane formation is the polysulfone and, in this regard, tests were performed to analyse the ways to mix an epoxy resin with polysulfone. The idea had generated a study regarding the properties of such a mixture together with the condition that had to be reached to successfully get the mixture. Low-polar solvent solution of polysulfone had been obtained with 1-methyl-2-pyrrolidinone. After compatibility tests, 15 and 20% of this solution was added to the components of the epoxy systems -with the epoxy resin -and formed materials were analysed by mechanical means-compressive and three-point bending - the surprise was that some materials had showed memory shape properties.

Abstract: The main aim of this study was to investigate a mixture of two poorly water-soluble active pharmaceutical ingredients (APIs): an angiotensin II receptor antagonist (valsartan) and a calcium channel blocker (amlodipine besylate), chosen in a fixed-dose, in order to obtain new polymeric nanoparticles (NPs) for cardiovascular diseases treatment. NPs were prepared via nanoprecipitation method using poly (D,L-lactide-co-glycolide) (PLGA) as matrix and Pluronic F127 as stabilizer. Three formulations were investigated with different ratios of AML:VAL:PLGA (1:16:5, 1:16:7.5 and 1:16:10). Particle size, polydispersity index and zeta-potential analyses were performed to characterize and optimize the formulation. The in vitro drug release study was determined by using a dialysis membrane method under sink conditions. All NPs loaded with both APIs showed nano-size, negative potential, a high homogeneity and a slow drugs release in physiological environment.

Abstract: Standard procedures regarding osteoblast cells deposition on different subtrates to test the biocompatibility of materials are not available. Aspects related to cells morphology depending on their number on the surface area of the substrate were studied for the first time. Osteoblasts were successfully isolated from residual bone resulted from two different patients after total hip arthroplasty. Different numbers of osteoblasts in populations (3x104 cells/cm2, 6x104 cells/cm2, 1x105 cells/cm2) were deposited on tissue culture polystyrene for 7 and 10 days of incubation. Results suggested that the protocol of osteoblasts deposition should be adjusted to assure a fair distribution of cells on the entire available area of the substrate, possible if a very good dispersion in the medium is achieved prior to deposition. Some other key factors in cells appropriate development, such as substrate nature, topography and incubation time,were detected. The present investigation helps declaring specific standards with respect to the biocompatibility testing of materials using osteoblast populations. Further investigations may lead to the creation of databases and the establishment of standards regarding bicompatibility researches that involve osteoblasts populations.

Abstract: Dental resin composites have a wide applicability in the dental field. They exhibit their own chemical composition that imparts certain physico-mechanical properties. The machining of the pieces of these composites must be sufficiently light, without affecting their strength. For processing these parts, respectively of the dental work, is used or carbide burs, or diamond burs, depending on the mechanical strength of the composite. To determine composite behaviour under action of the conical finishers was simulated their behaviour in specific simulation programs. As a result, stress concentrators may appear from the first processing which may affect the later resistance of the piece or dental work.

Abstract: During conûict situations, the combat staff is exposed to a wide variety of aggressions, such as temperature and pressure variations and dynamic impacts (from ammunition or fragments). Textiles used in the manufacture of the military uniforms and devices have always played an important role in defending the military against these hazards, and an adequate level of individual protection equipment is required. In this respect, novel fibre-reinforced polymer composite materials for military application, such as reducing blunt trauma for ballistic protection equipment, have been studied in terms of thermal and mechanical properties and ballistic protection, obtaining very good results.

Abstract: By electrical determinations, digital microscopy and visual observations, the anticorrosive insulation capacity of the paint layers applied to the three sections of a bridge over the Tisza River was assessed. The visual observations have highlighted the fact that on the Eastern section repainted in 2013, biofouling increases are significant (covers up to 10 % of the surface) - both ferns have been identified (Hypogymnia physodes and Xanthoria parietina), filamentous molds (Aspergillus fumigatus and Aspergillus niger) as well as algae and moss (green - capable of photosynthesis). On paint applied in 1986, no bio fouling was visible but the painting material is aged and shows rust traces (5-10 % of the surface) and exfoliation between the paint layers (10-20 % of the surface). No bio fouling and/ or exfoliation/ degradation of the paint layer have been observed on the paint applied in 2014. Determinations of electrical insulation resistance correlated with those of the paint layers’ thickness are closely related to the visual observations. The values obtained for the specific resistivity of the paint layers applied in 2013 (with bio fouling increases) are approx. 38 times lower than those applied in 2014. These findings suggest that the painting material used in 1983 for the top coat realization, showed major qualitative vices.

Abstract: The influences of hypochlorite DM with oil ingredient and without it, which is introduced into the armament not only by the Czech Armed Forces Chemical Corps, but also by the chemical services specialists of the Czech Republic Fire Rescue Service, on a substrate consisting of a barrier material based on isobutylene-isoprene rubber (butyl rubber) were presented in this paper. Based on the repeated exposure of the substrate formed by the barrier layer material selected by this decontamination mixture and its subsequent rinsing, a change of the breakthrough time has been studied using the MIKROTEST method employing the chemical warfare agent of sulfur mustard and Congo red as a detecting agent.

Abstract: The survival of CKD patients has known significant improvement with the appearance of extrarenal clearance methods. Being a domain in a rapid progression, the hemodialysis membranes have been, in time, one of the key modifying points. In this paper will make a short presentation of the features of hemodialysis membranes and will point out aspects which need future research.

Abstract: This paper presents the development of dynamically cured polymer composites and nanocomposites based on plastomer - PP (polypropylene) and EPDM elastomer (ethylene-propylene-diene-terpolymer) compatibilized and reinforced with nanometric particles-MMT (montmorillonite, chemically modified layered clay) in two stages, by extrusion-granulation and mixing. Nanoparticles increase the thermal resistance of dynamically cured polymer nanocomposites. By means of compatibilization and dynamic curing, elastomer particles - EPDM are more easily dispersed in the mixture. The materials obtained were tested physicomechanically (Melt Flow Index) and morpho-structurally (FT-IR and DSC).

Abstract: Gene therapy represents a promising method for treating genetic disorders or diseases consisting in the transfer of genetic material (DNA) to cells in order to substitute or to slow down the evolution of the defective gene in cells. Theoretical models to predict DNA release are difficult to build in the classical approach of continuous and differentiable physical quantities, due to the high number of interdependent phenomena that occur simultaneous. The article presents a theoretical model based on the fractal theory of motions in the form of Scale Relativity Theory to describe nonlinear behaviors in gene therapy. Correlations of the theoretical model with experimental data are also observed.

Abstract: Over time, anatomists have been concerned with the preservation of anatomical parts for a long time. Thus, in the modern era, both colouring and fixing substances, as well as plastic and corrosive materials have been used in the manufacture of corrosion and plastinated specimens. The ultimate aim was to make the dissected anatomical specimens as lasting and accurate as possible. Thus, parenchymal viscera, which have a certain tissue thickness, greater than in the tubular viscera, are more difficult to preserve and obviously to dissect. The time required to preserve those increases accordingly. In our study we have used 62 formalized adult human kidneys, belonging to 31 bilateral dissected bodies, different age and gender, 20 males and 11 females. We have removed all the kidneys from the renal fossa and we have made 23 corrosion casts, and 39 specimens have been plastinated. There have been dissected 30 structures considered as normal in size and morphological aspect and 9 have been preserved entirely because they did not fit within the normal physiological limits. All 39 kidneys have been undergone to S10 Biodur rubber silicone technique preservation.

Abstract: Uterine sarcomas are rare but very aggressive gynecologic malignancies. The most frequent signs and symptoms at the moment of diagnosis include abnormal uterine bleeding or diffuse abdomino-pelvic pains while acute abdomen by uterine rupture is an uncommon situation. We present the case of a 72 year old patient who presented in emergency for diffuse abdominal pain and hypotension. An emergency laparotomy was performed and a ruptured uterine tumor with small bowel and sigmoidian serosal invasion and intra-peritoneal bleeding was found. The tumor was resected en bloc with total hysterectomy, bilateral adnexectomy, segmental enterectomy and sigmoidectomy, pelvic and para-aortic lymph node dissection. The histopathological and immunohistochemistry examination revealed a poorly differentiated sarcoma. Although it is a rare condition, a uterine sarcoma can rupture and cause hemoperitoneum; emergency surgery while respecting oncologic principles of complete resection is mandatory.

Abstract: This paper presents a study on the behaviour of composites based on natural rubber and plasticized starch after aging under temperate climate conditions. Natural rubber blends containing different amounts of glycerine-plasticized starch as biodegradable filler were made. Analysis of samples after being kept for 1 year in temperate weather conditions shows a change in the surface of vulcanizates due to the influence of atmospheric factors. Surface oxidation and degradation was highlighted by: FTIR analysis (appearance of -OH, -COOH groups, etc.), SEM microscopy (appearance of cracks on the surface), immersion in water. The degradation of the materials is also highlighted by the decrease of the physical-mechanical properties, the gel fraction and crosslinking degree. The best aging behaviour was observed in the mixture containing a low amount of biodegradable starch and the worst behaviour was that of the control starch-free mixture.

Abstract: In this paper is studied the hot plastic deformability (plasticity and resistance to deformation) for the low-alloyed steel of heat treatment for mechanical engineering in two ways: compression and tension. Groups of low alloy steels is very important in terms of quality and quantity, the products of these steels have developed internal and external market. The plasticity variation were plotted with the temperature and it was established that the plasticity of the steel increases in the range 700-12000C, then decreases as a result of the firing of the grain boundaries, for the bars obtained from ingot and continuous cast blown it was noticed that the plasticity values are very close. Deformation resistance decreases as the temperature increases. The finest granulation was obtained for a final plastic deformation temperature of 8000C and a minimum degree of deformation of 45%.

Abstract: The aim of this in vitro study is to compare the load-to-fracture performance of polymethyl methacrylates (PMMA) provisional restorations manufactured with a traditional laboratory technique in comparison to a computer-assisted design and computer-assisted manufacturing (CAD-CAM) technique. Five interim three-unit fixed dental prostheses were fabricated with the conventional indirect technique, on a standard typodont. The same model was scanned with an intraoral scanner and the digital design of identical fixed dental prostheses was made. Then other five interim three-unit fixed dental prostheses were milled from PMMA CAD/CAM blocks with an in office milling machine. All specimens were tested for flexural strength in a universal testing machine, and the maximum load to fracture was measured. For the conventional provisional restorations, the load to fracture was 121.16 ± 24.6, in comparison to CAD/CAM interim restorations, for which the load to fracture was 728.88 ± 228.7. Within the limitations of this study, one can conclude that CAD/CAM provisional restorations present a higher fracture load than the conventional manufactured interim restorations.

Abstract: Ultra-High Molecular Weight Polyethylene (UHMWPE) composites are the result of recent developments in material research for ballistic protection due to their ability to absorb the kinetic energy of the bullet by various mechanisms of dissipation, among which an important one is delamination. In order to study this mechanism independently, the laser induced shock wave testing procedure has been used on thin Tensylon® laminate samples. Laser-induced shock represents a modern approach that can be used for assessing the interlaminar bond strength between two plies of a composite material, in dynamic conditions, at high strain rates representative for a ballistic impact. Through this technique, a delamination failure stress threshold can be determined. In the present work, the laser induced shock technique was applied on the commercial UHMWPE material called Tensylon®. The delamination threshold of this material was determined by using the Novikov approach, and, compared to the literature, the results match the values determined by other means of measurement.

Abstract: Skin- and mucosal infections, especially purulent, can often cause diagnostic and treatment problems. Therefore, we intend to conduct a microbiological study of isolated bacterial strains from ambulatory patients with various cutaneous-mucosal infections. In isolated strains we determined the sensitivity to antibiotics and we established the phenotypes of resistance in which they fall. We took in account 98 strains isolated by a private laboratory in Timisoara between January 2016 and December 2017. After bacterial identification, sensitivity testing to antibiotics was realized using Kirby-Bauer disc diffusion according to the CLSI standard. Antibiogram was performed for all strains except for Streptococcus pyogenes. By interpreting the antibiograms, the phenotypes of resistance were determined. Most infections were caused by Staphylococcus aureus. In order of frequency following strains were isolated: Staphylococcus aureus (75.52%), Streptococcus pyogenes (11.22%), Pseudomonas aeruginosa (7.14%), E. coli (4.08%) ’i Enterobacter spp. (2.04%). S. aureus strains were resistant to penicillin in 94.60% of cases. We observed a higher sensitivity to oxacillin (87.84%), tobramycin (86.49%), gentamycin (87.84%), ciprofloxacin (83.78%) and clindamycin (89.20%). Most strains of S. aureus were of phenotype Peni-R Meti-S (82.44%). 12.16% were of phenotype Peni-R Meti-R (MRSA) and only 5.40% were sensitive to betalactams (Peni-S Meti-S). Gram-negative bacilli strains (Pseudomonas aeruginosa, E. coli, Enterobacter spp.) were less resistant, all being wild strains. Determining antibiotic resistance phenotypes is necessary in order to be able to make the right decision when choosing anti-infectious treatment, but also to prevent the selection of multi-resistant bacterial strains. The presence of MRSA at a rate of 12.16% is an alarm signal because the MRSA strains are multi-resistant to antibiotics with cross-resistance to the betalactams. Resistance usualy extends also to other classes of antibiotics. For a correct diagnosis and treatment, the results of the bacteriological testing need to be corroborated with the clinical signs.

Abstract: The objective of this in-vitro study was to compare if there are any differences in the marginal fit of crowns fabricated by CAD/CAM technique. We used three different types of materials (two types of polymethylmetacrylate (PMMA) provided by two different manufacturers and one type of hybrid ceramic) and three different types of impressions: intraoral scanning, model scanning and conventional impression scanning. The crowns were subsequently measured with an electronic microscope at 1000X. Our results showed better results for the hybrid ceramic. The differences between the PMMA were not significant. There were no statistic differences with the ANOVA analysis between the scanning methods. Best combination in terms of marginal fit was found with hybrid ceramic and intraoral scanning.

Abstract: The incidence of postoperative pain in patients operated for inguinal hernia can reach up to 40% of cases, depending on different authors, and depending on the approach used in the surgical treatment of these patients. Currently, there are two commonly accepted ways of surgical treatment of inguinal hernias, the classic approach with polypropylene mesh (Liechtenstein technique) and the laparoscopic approach. The purpose of this study was to conduct a comparative analysis on the need for analgesic medication in patients treated for inguinal hernia either by classic (group A) or by laparoscopic (group B) approach. Surgical meshes were used in all patients enrolled in our trial. The average age of the patients included in this study was 53.79 years, ranging from 20 to 88 years. Regarding the distribution of cases by gender, we observed in the studied lots that 12 cases were women (11.53%) and 92 cases were males (88.46%). In female patients, the classic inguinal hernia approach was performed in 3 cases (25% of cases), and in 9 cases the laparoscopic approach was performed in the surgical treatment of the inguinal hernia (75% of the cases). In male patients, laparoscopic approach was performed in 33 cases (35.86% of cases), and in 59 cases the surgical approach was performed in a classical manner using the Liechtenstein technique (64.13% of the cases). From the statistical analysis of the data we noticed a statistically significant difference in the need for analgesic medication administered to these patients (p = 0.0001). Although surgical correction of inguinal hernia, both classic and laparoscopic approaches, provide adequate treatment for these patients, in case of the laparoscopic technique, immediately after the operation, the need for analgesic medication is lower compared to the classical technique.

Abstract: The phytotherapy is based on the consume of fruits, vegetables and medicinal plants; they contain mixtures of bioactive chemical substances (carotenoids, phenolic acids, flavonoids, coumarins, tannins, organosulfur compounds) with synergic effects on the treatment of diseases. Nano- and micro-carriers are very useful drug delivery systems which can improve the transmembrane transfer of natural extracts. In the present study, betulin and two birch bark extracts were encapsulated inside polyurethane microstructures. Structures’ size, homogeneity and surface charge were studied using a Zetasizer, while DSC analysis was involved to assay structures’ thermal behavior. Irritation effects were monitored by non-invasive techniques on human skin. The results indicate the obtaining of structures with size around 200-250 nm, with a positive surface charge and a very good thermal stability. The non-irritation potential recommends these structures as a safe delivery system used for natural extracts.

Abstract: The paper presents the laboratory experiments and the results obtained regarding the production and characterization of composite materials with coconut fiber for the manufacture of brake pads for small vehicles and medium performances. The experimental research of composite material with organic components determined the influence of some material factors and parameters of the sintering regime on the physico-mechanical characteristics of the tested samples. Knowledge of these characteristics offers the possibility of pertinent appraisals regarding the behaviour of the composite materials intended for used in brake pads applications. Materials with the best features will be selected to determine the functional characteristics of friction and wear.

Abstract: In most patients with complete or partially stretched edentations requiring a dental implant, there is insufficient alveolar bone for a proper morpho- functional prosthetic restoration. Therefore, in many cases a bone addition is required for the implant treatment. The aim of this study is to evaluate ex-vivo, with numerical simulations, a large mandibular bone defect that is restored by using a three-dimensional (3D) printed ceramic scaffold. In order to obtain a proper morphological and functional prosthetic restoration, a thick mandibular bone is utilized for the implant treatment. The polymeric scaffold is attached to the mandibular bone with one, two, or three implants. By scanning the mandible with MicroScribe 3G and then employing a Finite Element Analysis (FEA) with Pro/Engineer and ANSYS 15, the study performs a numerical simulation and thus assesses the effects of the force applied to the scaffold.

Abstract: A class of intensively studied materials with application in areas where complex structures with precise geometry are needed (i.e. electronics), are the self-organized nanomaterials. Polymer, metallic and composite self-organized nanomaterials have been in researchers’ attention the last decades. They are not only appealing scientifically, by revealing the intrinsic atomic and molecular interactions that might be difficult to detect otherwise but may also hold the key for the development of novel functional structures and devices. The different mechanisms and forces involved in the self-formation of organized nanostructures are discussed in the present manuscript. Further on, key formation fundamentals involved in the fabrication of self-organized nanostructures are described. Between the known manufacturing methods, the electrochemical synthesis is considered extremely simple and cost effective. On the other hand, it involves a wide range of synthesis parameters (e.g. voltage, electrolyte type, temperature, experiment duration, pH etc.) that may lead to the formation of ingenious structures with complex geometries at different length scales. Finally, some representative scientific investigations are mentioned together with applications of self-organized nanomaterials in different engineering and life areas.

Abstract: The experimental results obtained by studying the influence of different types of fibers on the mechanical properties of fly ash polymer concrete are presented in the paper. The general demand of using wastes found applicability in building material industry because some of them are beneficial in improving concrete properties. The waste additions type fly ash and fibers were incorporated in polymer concrete. The study focused on fibers type glass, polyester, metallic and cellulose. The mechanical properties such as compressive strength, flexural strength and split tensile strength were investigated having in view the type, dosage and length of fibers. The results show that fibers improved mechanical properties in comparison with that of polymer concrete without fibers, the test results being differently influenced by the factors which were considered.

Abstract: Composites made from metallic fillers embedded in polymer matrix have good shielding properties as electrical point of view and tribology properties from mechanical point of view. These properties depend on amounts, shapes, sizes, and combinations of fillers and matrix. This paper proposes an electromagnetic method for determination of metallic fillers concentration in composite materials from metallic fillers embedded in polyester matrix. The bulk resistivity and dielectric permittivity were measured but these measurements are less influenced by the fillers concentration. The amplitude measurement of e.m.f induced in the reception coil of the focalized electromagnetic transducer and their averaging for the scanning of a relative large zone of the composite has proven to be an efficient method. The average amplitude linearly decreases with the increasing of fillers concentration, and has different values for Cu and AISI 316 fillers.

Abstract: The classical method of teaching human anatomy to students is based on the dissection of human cadavers. Nowadays, there are many ethical controversy regarding the use of human cadavers during anatomy courses. In our study we tried to get undergraduate students’ opinion about some different techniques of teaching human anatomy, including the utility of plastic models. We introduced in this study 163 students in the first year of their study at the Faculty of General Medicine from the University of Medicine and Pharmacy, Tirgu Mures. The respondents were asked to fill in a 12-item anonymous questionnaire. Based on the answers provided in the questionnaires we divided the 163 respondents into 2 groups: group A comprising 113 (69.32%) respondents who found that the best method of teaching anatomy is cadaver dissection and group B comprising 50 (30.67%) respondents who found that the best method of teaching is not cadaver dissection. Thus, 20 (12.26%) respondents considered that the best method of teaching anatomy is the use of previously dissected and preserved preparations, 4 (2.45%) indicated the use of plastic models as the best method, 24 (14.72%) would prefer 3D techniques of image reconstruction and 2 (1.22%) respondents found that the best method of teaching anatomy is by Microsoft Office PowerPoint presentations. Even though there are still controversial opinions regarding the use of cadaver dissection in teaching and learning human anatomy, especially ethical and psychological ones, cadaver dissection remains the best method of teaching anatomy to undergraduate students in medical schools.

Abstract: The acoustic comfort includes the protection against noise and it is closely related to the sound absorption concept. This paper presents an experimental study on sound absorption coefficients, for some composite materials: waste materials (rubber crumbs, textile, flax fibers) mixed with rigid polyurethane foam as binder. The composite materials were characterized both acoustically (sound absorption coefficient) and also in terms of heat transfer (thermal conductivity). The acoustic absorption coefficient was determined using the impedance tube and the influence of structure of these materials on the sound absorbing properties was analyzed. The experimental results show the sound absorption performances of some composites based on recycled waste materials, thus promoting environmentally friendly solutions.

Abstract: Because cyancobalamin deficiency is commonly treated with parenteral adminstration, the present study aims to make a comparison between the effectiveness of parenteral vitamin B12 treatment and the effectiveness of local treatment achieved by complete dentures improved by crosslinked polymerization using as template vitamin B12 (cyanocobalamin).

Abstract: The aim of this study was the development and formulating of a cosmetic product and the assessment of compatibility tests performed on the product, transfered to the cosmetic jar. Sample of cosmetic cream were stored using 50 mL PP (Polypropylene) plastic containers. The developed cosmetic formulation was monitored under accelerated stability studies. Accelerated stability tests were performed over a period of 30 days while maintaining the product at 4, 20 and 40°C. Quality control initial, and after initiating the accelerated stability test was performed for the developed cosmetic formulation.

Abstract: The developments in the biocompatible materials and additive manufacturing technologies gave birth to new possibilities in reconstructive surgery. In addition to revolutionizing the diagnostic possibilities, the modern medical imaging has led to the development of surgical planning software. Using these state-of-the-art technologies, a new standard of care is rising with the spread of patient specific implants. Our view in studying and using these materials and technologies goes beyond their biocompatibility, focusing on the functional and esthetic impact of these restorations. Our aim is to show their potential benefits and pitfalls presenting a couple of posttraumatic and oncological application possibilities, focusing on the new presurgical planning, choice of materials and manufacturing technologies.

Abstract: The aim of the study was to evaluate the influence of different techniques of finishing and polishing as well as the use of sealants on the surface condition of some composite resins used in the dental office. 80 specimens of composite materials (Nanoceramic, Nanocomposit and Nanohybrid) were made and divided into 3 groups G1-coated composite with sealant lacquer, G2 - finished in 2 stages, and G3 - finished in 3 stages. Roughness (Ra) was determined with the Taylor Hobson Form Talysurf Profiometer. The data was analyzed using one-way ANOVA followed by a multiple comparison t test. Significant differences were found between the groups in terms roughness (p < 0.001). The results showed that Seal – and - Shine (PULPDENT) was capable of reducing surface roughness and provided polished surfaces for all materials.

Abstract: The research concerns the transmission of electromagnetic waves with a wavelength corresponding to the visible part of the spectrum and part of the ultraviolet and infrared radiation range. Light transmittance through ocular lenses was tested using a UV-Vis spectrophotometer for the wavelength range 250-850 nm. Obtained results encourage reflection on the quality of the spectacle lenses produced. The obtained results do not confirm the assurances of producers about the increase in light transmittance in the range of wavelengths corresponding to the highest sensitivity of the human eye. In addition, lenses having UV protection coatings do not perform their function in a proper way. Eyeglass lenses of various classes were tested, equipped with various refining coatings. The effect of the number of coatings on the transmission of light through the lenses was not observed. Conducting and publishing studies such as those presented in this work may have a significant impact on the improvement of the quality of manufactured eyeglass lenses.

Abstract: The article focuses on the behavior of the non-conventional treated alloyed steel in magnetic field, during the dry wear tests. It is a review of the experimental tests from last years. The thermo-magnetic treatments have been applied before the application of a thermo-chemical treatment in plasma based on diffusion process. The study was made in order to improve the mechanical properties of the alloyed steel during the friction wear. Thermo-magnetic treatment applied before the plasma nitro-carburizing treatment improves the mechanical properties of the material especially in this case, for a steel that has a considerable content of Chromium (1.02%). The behavior was studied using X-Ray diffractometry of the superficial layers during the dry friction of wear process. The wear tests used an Amsler machine, during three hours of wear tests. After each hour of the wear tests the samples have been analyzed. The diffractometric characteristics of the superficial layers obtained after a complex array of thermo-magnetic and thermo-chemical in plasma treatments, the phases distribution, the content of the superficial layers and the behavior of the steel during the wear through dry friction tests, have been considered as criteria.

Abstract: The aim of this study was to evaluate and to compare the compression behavior under identical mechanical tests, of three different composite resins, by determining Young’s modulus for compression, ultimate compressive strength and ultimate compressive strain. The studied materials were: Filtek Z250 Universal Restorative, Filtek Z550 and Filtek Bulk Fill Posterior Restorative (3M ESPE, St. Paul, MN, USA). Fifteen cylindrical samples, having 6 mm in height and 5 mm in diameter, were made from each material, using plastic molds. The samples were subjected to quantitative analysis of the compression behavior after mechanical tests. The fractured fragments of the samples were subjected to qualitative surface evaluation by scanning electron microscopy. Results were statistically analyzed using one-way analysis of variance (ANOVA) with Tukey’s post hoc test. Filtek Z250 had the lowest value of Young’s modulus for compression and the results were statistically significant (p < 0.05) when compared to Filtek Bulk Fill Posterior Restorative and Filtek Z550. There were no statistically significant differences between all three materials regarding ultimate compressive strength (p > 0.05). The lowest value for ultimate compressive strain was recorded for Filtek Bulk Fill.

Abstract: The AISI H21 steel used for dies in copper hot extrusion softened only after several runs. To improve production parameters a new material was necessary for the die, and, as a first choice, Inconel 718 was preferred. Prior to adopting this material for new extrusion dies an experimental program with temperature exposure cycles was performed so as to study microstructure evolution within AISI H21 and Inconel 718. The samples were studied by optic and scanning electron microscopy (SEM) and were also submitted to X-ray diffraction (XRD) and microhardness tests. The results showed carbide coalescence, which led to softening, followed by a re-precipitation in the steel, while, in Inconel 718, the precipitation (in small amounts) of delta (ä) phase was observed.Using these results and combining them with practical experience with steel, we could predict that the Inconel 718 die performance is such that at least a double quantity of copper could be extruded per die.

Abstract: Due to mechanical resistance characteristics, chemical corrosion and abrasive erosion resistance, the polymers are more widely used in equipments and installations that are exploited in different fluid hydrodynamic conditions. Among these applications there is the protection of surfaces of hydromechanic organs stressed by cavitation, like in hydraulic machines rotors and valves. Consequently, the research aimes the extension of using these and protection of other components surfacess hardly streesed by cavitation. The research in this paper points toward the behavior of modified polymer layer, coated on surfaces of bronze used in casting the propellers of maritim and river ships. The tests were performed in standard piezoceramic crystal vibrating equipment within Cavitation Laboratory of Politehnica University of Timisoara. The damaging intensity of equipment is much greater than any cavitational vortex, created by ship propeller, hydraulic turbine or centrifugal pump. The obtained results, compared to both recorded on uncovered surfaces with polymer layer and recorded on surfaces covered with HVOF composite materials layers, show an increased resistance that implies the increased exploiting duration of those surfaces.