bluuebunny/crossref_metadata_2025 huggingface dataset:
Study Deformability Ecological Steel (41Cr4)
Authors: Rusanescu Carmen Otilia , Rusanescu Marin , Anghelina Florina Violeta , Popescu Ileana Nicoleta
Published: January 2020

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%.
Comparative Study on the Need for Postoperative Analgesic Medication After Surgical Treatment of Inguinal Hernia with Surgical Mesh through Laparoscopic or Classic Approach
Authors: Suciu Bogdan Andrei , Halmaciu Ioana , Fodor Decebal , Trambitas Cristian , Godja Dumitru , Clipa Adriana , Nicolescu Cosmin , Brinzaniuc Klara , Vunvulea Vlad
Published: January 2020

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.
Nondestructive Evaluation of Metallic Fillers Embedded in Polyester Matrix
Authors: Steigmann Rozina , Savin Adriana , Iftimie Nicoleta
Published: January 2020

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.
Comparative Study Regarding the Compressive Strength of Different Composite Resins Used for Direct Restorations
Authors: Nica Irina , Iovan Gianina , Stoleriu Simona , Ghiorghe Cristina Angela , Pancu Galina , Comaneci Radu , Andrian Sorin
Published: January 2020

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.
Analysis of Acacia Wood Reinforced PLA/PHA Blend Composites
Authors: Bakri Muhammad Khusairy Bin , Jayamani Elammaran , Heng Soon Kok , Kakar Akshay
Published: January 2020

This research focuses on the analysis of acacia wood reinforced PLA/PHA blend composites. Acacia wood was processed into small chip particles, which were mixed with pure PLA, pure PHA and PLA/PHA blend. The wood was treated using acetic acid and sodium bicarbonate. It was then compressed into sheet film. The micrograph shows that the PLA and PHA mixture create an interlocking continuous structure and the addition of wood strengthens interlocking between PLA and PHA. Mixtures of this blend also reduce bubble and crack, and create new properties superior than the earlier properties of existing PHA and PLA.
Fine Details Obtained by 3D Printing and Using Polymers
Authors: Slatineanu Laurentiu , Dodun Oana , Nagit Gheorghe , Coteata Margareta , Bosoanca Gheorghe , Besliu Irina
Published: January 2020

The three-dimensional printing is a manufacturing method involving the addition of materials by using certain principles valid in printing techniques. There are various techniques of a three-dimensional printing method and the most of them could be applied inclusively to generate objects of polymers. The objective of the research presented in this paper was to analyze the capabilities of 3D printing process or equipment of generating fine details and to identify a way of evaluating these capabilities when using polyester PLA as filament material. The systemic analysis of the printing techniques which use a fused polymer filament deposition showed that there are some groups of factors able to affect the obtaining of fine details. An experimental research was designed in order to highlight the influence exerted by the diameter of the nozzle orifice and by the values of sharp angles of isosceles triangles on the heights of these triangles, thus obtaining an image concerning the possibilities of generating sharp edges by three-dimensional printing. To evaluate the capacity of the 3D printing process of obtaining thin walls, a spiral including linear segments with a decreasing thickness from 1 mm was also achieved on the test piece. By mathematical processing of the experimental results using a specialized software, empirical mathematical models were determined to evaluate the intensity of influences exerted by the two process input factors on the heights corresponding to isosceles triangles characterized by sharp angles.
Melt Shear Rheology and pVT Behavior of Polypropylene / Multi-Walled Carbon Nanotube Composites
Authors: Stanciu Nicoleta Violeta , Stan Felicia , Fetecau Catalin
Published: January 2020

In this study, capillary rheological tests were performed on polypropylene filled with multi-walled carbon nanotubes (PP/MWCNT) to determine the melt flow curves and pressure-Volume-Temperature (pVT) diagrams. Based on the experimental data, master viscosity curves were constructed using the time-temperature-superposition principle and the Cross and Carreau-Winter models, while the pVT data were fitted to the Tait equation in both liquid and solid states. Results show that the melt shear viscosity decreases with increasing melt temperature and shear rate and increases with MWCNT wt.%. All composites display shear-thinning behavior in the range of medium to high shear rates. The specific volume of PP/MWCNT composite decreases with increasing MWCNT wt.% and pressure and increases with increasing temperature.
Carbon Fiber Reinforced Polymers Used for Strengthening of Existing Reinforced Concrete Structures
Authors: Dan Sorin , Bob Corneliu , Badea Catalin , Dan Daniel , Florescu Constantin , Cotoarba Liliana , Pode Vasile , Gruin Aurelian
Published: January 2020

The paper deals with some aspects regarding the behavior of modern and efficient solutions - for rehabilitation of reinforced concrete framed structures. The paper is devoted to experimental studies on carbon fiber reinforced polymer (CFRP) systems used as strengthening solution for reinforced concrete (RC) frames assumed as existing structures, which were tested as un-strengthened and as (CFRP) strengthened structures. Single span and single story frames (scale 1:2) were designed and detailed according to the Romanian design codes from 1970s under which seismic design was inadequate. The RC design and the magnitude of applied forces were ensuring the failure mechanism, of non-strengthened RC frames, by plastic hinges at columns ends. Then the columns were strengthened by using CFRP materials. The experimental program emphasized some important aspects regarding the behavior and failure by debonding of CFRP strengthening materials applied to RC frames. The analysis of experimental data and theoretical values showed up an increase of resistance and stiffness achieved by strengthening.
Evaluation of Dental Composite Resin Interface and Adhesion Using Laser Scanning Confocal Microscopy
Authors: Stan Adrian Tudor , Vaduva Adrian , Negrutiu Meda Lavinia , Sinescu Cosmin , Szuhanek Camelia , Rogobete Alexandru , Muntean Danina , Talpos Serban , Duma Virgil Florin , Idorasi Laura , Hajaj Tareq , Rominu Mihai
Published: January 2020

The aim of the study was to evaluate and to compare the interface and marginal leakage of dental composite resins using confocal laser scanning biological microscopy (CM). Ten class II cavities were prepared on the proximal surfaces of 10 extracted teeth, previously kept in 10% formalin to preserve the bonding properties of the tooth structures. Cavities were restored with dental composite resin using the �open sandwich� technique and then assessed using CM. Open marginal adaptations at the interfaces inside the composite resins were identified. The results obtained with CM helped to eliminate and reduce the background information collected from a distance from the focal plane and allowed for the acquisition of serial optical sections from thick tooth specimens. In vitro assessments were thus made using CM on the teeth structure, regarding the occurrence of potential micro-leakages at the restoration interface.
Assessment of Paint Layers Quality 2. Identification of biological species grown on a railway bridge
Authors: Nicula (Butoi) Nicoleta Oana , Varga Emese , Bors Adriana Mariana , Lingvay Iosif
Published: January 2020

The species from the increased biofouling on the paint layers applied to the metallic strength structure of a railway bridge located in a Natura 2000 protected area have been identified by specific biologic and microbiological methods. As a result of the analysis of the biological samples taken on the field, it has been found that relatively large variety of filamentous molds are present (Aspergillus fumigatus, Asprgillus flavus, Aspergillus niger, Paecilomyces variotii, Chaetomium globosum, Trichoderma viride, Stachybotris atra, Trichoderma sp., Alternaria sp and Penicillium sp.). Samples also show, lichens (Xanthoria parietina and Hypogymnia physodes) and lower plants capable of photosynthesis such as algae (Chlorophyta Xanthophyceae, Chrysophyceae) and moss (Lunularia cruciata, Marchantiophyta).
Using Ansys for Design and Numerical Study of a Specific Fixed Wing UAV
Authors: Murariu Gabriel , Mahu Razvan Adrian , Murariu Adrian Gabriel , Dragu Mihai Daniel , Georgescu Lucian P. , Carp Bogdan G.
Published: January 2020

This article presents the design of a specific unmanned aerial vehicle UAV prototype own building. Our UAV is a flying wing type and is able to take off with a little boost. This system happily combines some major advantages taken from planes namely the ability to fly horizontal, at a constant altitude and of course, the great advantage of a long flight-time. The aerodynamic models presented in this paper are optimized to improve the operational performance of this aerial vehicle, especially in terms of stability and the possibility of a long gliding flight-time. Both aspects are very important for the increasing of the goals� efficiency and for the getting work jobs. The presented simulations were obtained using ANSYS 13 installed on our university� cluster system. In a next step the numerical results will be compared with those during experimental flights. This paper presents the main results obtained from numerical simulations and the obtained magnitudes of the main flight coefficients.
Use of the Finite Element Analysis Method in Pedodontics
Authors: Tanase Mihaela , Nitoi Dan Florin , Imre Marina Melescanu , Ionescu Dorin , Raducu Laura , Mihai Andrada , Stroescu Andra Elena Balcangiu , Balan Daniela Gabriela
Published: January 2020

The purpose of this study was to determinate , using the Finite Element Analysis Method, the mechanical stress in a solid body , temporary molar restored with the self-curing GC material. The originality of our study consisted in using an accurate structural model and applying a concentrated force and a uniformly distributed pressure. Molar structure was meshed in a Solid Type 45 and the output data were obtained using the ANSYS software. The practical predictions can be made about the behavior of different restorations materials.
Experimental Research into the Mechanical Behaviour of Dammar and Sandarac - Based Bio Resins
Authors: Bolcu Dumitru , Stanescu Marius Marinel , Ciuca Ion , Dinita Alin , Rosca Adrian , Rosca Daniela
Published: January 2020

In this paper, we examine two types of Dammar-based bio resins. In the first type, Dammar alone is used as natural resin, while in the second type a mixture of 70% Dammar and 30% Sandarac is used. Three sample sets were made of each of these resins with a bio resin volume proportion of 55, 65 and 75% respectively, the rest being epoxy resin (used, together with the associated reinforcing material, to generate a quick polymerization process). A SEM analysis is carried out and the surface roughness of each of the studied materials. A series of mechanical properties, determined by tensile testing, are presented. We have determined the characteristic curves, tensile strength and modulus of elasticity and the influence of the epoxy resin volume proportion on the mechanical behaviour of bio resins.
The Advantages of Bioresorbable INION� Implants in Traumatology Design, polymer composition and preliminary results
Authors: Scripcaru Andrei , Forna Norin , Ciubara Alexandru Bogdan , Benea Horea Rares Ciprian , Veringa Vlad , Sirbu Mihnea Theodor , Tudor Razvan , Sirbu Paul-Dan
Published: January 2020

Some disadvantages of traditional metallic implants used in orthopedics and traumatology prompted the development of bioresorbable polymer devices.The aim of this experimental study is to emphasize the characteristics of INION� resorbable implants (regarding design and polymers compositions), as well as to evaluate the results when using these innovative implants in two trauma cases. The polymers used in manufacturing INION� devices (Trimethylene Carbonate/TMC; L-Polylactic acid/LPLA; D,L Polylactic acid/DLPLA; Polyglycolic acid/PGA) degrade in alpha-hydroxy acids, gradually losing their hardness in 18-36 weeks with a complete bioresorption of 2-4 years. The clinical cases demonstrated the advantages of INION� plates (adapted shape, low profile, polyaxial screws, acceptable strength) or pins (allowing the aligmment and fixation of fracture, no migration). Among our patients, we found excellent results concerning the maintaining of primary reduced fracture, active range of motion, minimal pain with improving everyday comfort, no tissue or implant complications. Bioresorbable fracture fixation INION� devices are a viable alternative to traditional metallic implants, offering same significant advantages over them: the avoidance of long-term interference with gliding structures, keeping their strength long enough to support bone healing, no need to remove the implants, less pain, radiolucency, elimination of stress shielding and a lower risk of complications.
Waste Electrical and Electronic Equipment Study regarding the plastic composition
Authors: Grigorescu Ramona Marina , Grigore Madalina Elena , Ghioca Paul , Iancu Lorena , Nicolae Cristian-Andi , Ion Rodica-Mariana , Teodorescu Sofia , Andrei Elena Ramona
Published: January 2020

Waste electrical and electronic equipment (WEEE) generated in large amounts due to the development of IT and telecommunication industry is considered an important concern for environmental protection. The complex polymer composition of WEEE can be determined in order to consider a proper recycling process for polymeric materials. The aim of the study was to identify the constituent polymers by: density, burning test, solubility, Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), thermo-gravimetric analysis (ATG). The research led to a majority of polystyrenic polymers, together with polyesters, polycarbonates and polyamides.
Study on the Stability and Compatibility of the Cosmetic Products with Lavandula angustifolia Oil Kept in PPH Polypropylene Homopolymer Plastic Containers
Authors: Bogdan Mihaela , Endres Laura , Pasca Bianca , Tit Delia Mirela , Uivarosan Diana , Copolovici Dana Maria , Aleya Lotfi , Bungau Simona
Published: January 2020

The products used in cosmetic formulations are continuously diversifying as a result of researches in the field, which combine the healing and prevention of many skin conditions with the use of natural products such as vegetable extracts and essential oils. Testing the stability and compatibility of new or modified cosmetics is required to ensure that quality standards are met when stored in proper conditions for functionality and aesthetics, to preserve their chemical, microbiological and physical properties. In this study, the stability and compatibility of a new cosmetic product containing lavender essential oil in plastic container-plastic jar 100 mL PPH Polypropylene homopolymer (Moplen HP648T) is tested against the glass receptacle used as a control. The monitored parameters were organoleptic characteristics (appearance, color, fragrance), physicochemical (pH, density), under controlled temperature conditions, and the microbiological ones. The results of this study showed that the tested cosmetic product is compatible with the plastic container; data obtained were comparable with the organoleptic and physicochemical test results obtained in the case of the control sample stored at room conditions.
Simulation of Thermal Transfer Through the Polyamide Intake Manifold
Authors: Birtok-Baneasa Corneliu , Budiul-Berghian Adina , Socalici Virginia Ana , Bucevschi Robert
Published: January 2020

The aim of the present study is to model the steady heat transfer of the engine polyamide intake manifold. Under the condition of a steady flow, the intake manifold wall temperature and the intake air temperature were measured to examine the effect of the thermal boundary layer on the heat transfer. Experimental data is used to generate the numerical model of airflow simulation through the intake manifold.
Biopolymers - Carbon Sources for Composite Materials Used as Adsorbents for As (V)
Authors: Minzatu Vasile , Davidescu Corneliu Mircea , Negrea Adina , Ciopec Mihaela , Negrea Petru , Duteanu Narcis , Motoc Marilena , Velimirovici Dana
Published: January 2020

Large areas of S-E of Asia (Bangladesh), East of Europe (Hungary, West of Romania, Serbia), Nord and South America contain deep ground waters contaminated with arsenic. In these areas the quantity of arsenic in deep aquifers exceeds maximum allowed concentration of 10 �g/L. In order to use these water sources new adsorbent materials are required for their treatment. A composite material based on carbon and iron-oxide (used as surface modifier) present many advantages such as: chemical stability, higher removal efficiency, possibility of regeneration and very good selectivity for As(V) ions due to presence of iron-oxide particles onto the surface. The purpose of this study was to develop a new method to obtain a composite material using cellulose and soluble starch as carbon sources for the adsorbent material and iron chloride as precursor for the surface modifier. Produced composite material was characterized using several methods: TG-DTG, SEM, EDX, RDX and FT-IR. During experimental test obtained adsorbent material was used as adsorbent for As(V) removal form aqueous solutions. Arsenic residual concentration was measured using ICP-MS method. Maximum adsorption capacity obtained for adsorption experiments was 280 �g As (V)/g of adsorbent material.
The Influence of Oral Environment on the Optical Properties of Heat- pressed Ceramics
Authors: Vasiliu Roxana-Diana , Porojan Sorin , Porojan Liliana
Published: January 2020

The interest in aesthetics of dental materials is becoming greater with time and dental ceramics have proven excellent aesthetic properties. The study investigated how does the oral environment and the different surface finishing affect the optical properties and roughness of two types of ceramic, obtained using the heat- pressed method. Results showed that immersion has some influence on the optical and roughness of the two types of ceramics, but the major influence is made by the surface finishing and the type of ceramic. Lithium disilicate ceramic proved to have better optical properties compared to feldspathic ceramic. Roughness values showed that the parameters(Ra and Rz) were influenced by the surface finishing for both type of ceramics.
Encapsulation of Three Different Crude Extracts Rich in Triterpenes in a Biocompatible Polymer and their Evaluation in vitro for further Applications as Anti-inflammatory and/or Anti-tumour Alternative Therapeutic Agents
Authors: Biris Marius , Gluhovschi Adrian , Boruga Madalina , Lazureanu Voichita , Moza Iren , Boruga Ovidiu , Vlaicu Brigitha , Poenaru Marioara
Published: January 2020

Medicinal plants continue to be of real interest to researchers in interdisciplinary fields such as chemistry, pharmacy, medicine. Due to the metabolites in which it abounds, the plant material can successfully represent both a prophylactic and curative treatment. At present, countless studies, both in vitro and in vivo, are conducted to elucidate the pharmacological effects and establish the mechanisms involved. The actual experiment was purposed to evaluate the activity of raw birch bark, apple pomace and olive leaves extracts rich in triterpenes, formulated as PLGA nanoparticles, on normal/healthy different cell lines immortalized and of primary origin, such as keratinocytes, dermal fibroblasts, and gingival fibroblasts.
Some Aspects Conditioning the Achieving of Filaments for 3D Printing from Physical Modified Corn Starch
Authors: Dimonie Doina , Damian Celina , Trusca Roxana , Rapa Maria
Published: January 2020

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.
Using of Polymers for Rapid Prototyping of an Axial Microturbine Runner and Wicked Gates
Authors: Nedelcu Dorian , Cojocaru Vasile , Micu Lavinia Madalina , Florea Danut , Hluscu Mihai
Published: January 2020

Hydraulic turbine components that define the water flow, generally have a complex geometry. In the design of these components a major role is played by model tests. The complex geometry of runner�s blades and wicked gates determines high manufacturing times and high fabrication cost if they are made by classical manufacturing technologies (casting, machining on numerically controlled machines). The use of high resolution 3D printing reduces the production time, simplifies the manufacturing technology and generate high dimensional accuracy. The paper presents the design and the manufacturing process of the components from a new solution of axial hydroturbine, equipped with a permanent magnet generator and an immersed runner. The manufacturing of the main parts of the turbine (runner and wicked gates) it was made by Rapid Prototyping.
Antioxidant Activity of Entrapped alfa-tocopherol and Lutein in PLGA Nanoparticles in Wistar Rats
Authors: Miricescu Daniela , Totan Alexandra , Stanescu Iulia Ioana , Didilescu Andreea , Sfeatcu Ruxandra , Stanescu Ana Maria Alexandra , Stefani3 Constantin , Greabu Maria
Published: January 2020

The hypercaloric diet leads to obesity which is a risk factor for developing many systemic diseases such as diabetes, cardiovascular diseases and cancer. The purpose of our study was to observe the antioxidants effects of entrapped alfa-tocopherol (vitamin E) and lutein in Poly Lactic-CO-Glycolic acid (PLGA) in Wistar rats that received 3 weeks hypercaloric diet. Hepatic and splenic lysates have been used to detect changes in total antioxidant capacity (TAC) and advanced oxidative protein products (AOPP). The AOPP liver levels were statistically decreased in the case of rats groups that received a daily dose of PLGA-lutein or PLGA-vitamin E versus the control group. The AOPP level was decreased but statistically insignificant in Wistar rats spleen who received a daily dose of PLGA-lutein. At hepatic level, TAC was statistically increased in rats groups that received a daily dose of vitamin E or lutein. An increased statistical level of TAC was observed in the spleen cell lysing in Wistar rats who received the daily dose of PLGA-vitamin E. Entrapment of vitamin E and lutein in PLGA structure has diminished the effects of hypercaloric diet and can be considered a attractive and promising approach to enhance the bioavailability and activity of poorly water soluble compounds.
Interactions Between Dental Composite Resins and Saliva A comparative biochemical in vitro study
Authors: Pantea Mihaela , Ighigeanu Diana Andreea , Totan Alexandra , Greabu Maria , Miricescu Daniela , Imre marina Melescanu , Totan Cosmin , Spinu Tudor Claudiu , Petre Alexandru , Bencze Angelica , Milicescu Stefan , Tancu Ana Maria Cristina
Published: January 2020

This in vitro study analyses the biochemical interaction between saliva and three types of dental composite resins (a direct resin, an indirect resin and a dual-cure resin used for cementation of indirect dental restorations). The resin samples were obtained following a specific protocol and in line with the producers� recommendations; the resin samples were incubated with saliva samples collected from 19 healthy volunteers. The obtained results showed that the tested composite resins did not produce significant changes in oxidative stress parameters that were analysed (albumin, uric acid, GGT / gamma glutamyl transferase, OXSR-1 / oxidative stress responsive kinase 1) and do not influence the inflammatory salivary status reflected by the levels of IL-6 - an inflammatory marker.
Preliminary Investigation on Mechanical Properties of Polymer Coating Screws for the Future Fragility Fracture Fixation
Authors: Filip Alexandru , Badulescu Oana Viola , Sirbu Paul Dan , Veliceasa Bogdan , Puha Bogdan , Pascal Ionut Alin , Andrusca Liviu , Oprea Stefan , Filip Cristiana , Alexa Ovidiu
Published: January 2020

Bone fracture fixation uses both consecrated materials, such as metals/metal alloys, as well as synthetic materials. Synthetic materials are extremely versatile in terms of simulating biological structures, biocompatibility and, in some cases, avoid the subsequent interventions for removing the prosthetic material. Fixing an osteoporotic fracture presents major risks of failure due mainly to the bone fragility. To reduce the risk of failure, prosthetic materials have been improved with various cements. The purpose of the current study was to assess the mechanical properties of different orthopedic screws covered with a new polyurethane acrylate polymer (PUA) in order to improve the stability of the screw for the subsequent fixation of the fragility fracture. To test the efficiency of the new polymer, the breaking/fracture strength of the orthopedic screws coated with PUA was evaluated, in comparison with the screws without coating material. Our data shows that tested PUA improves the bond between the screw and bone. We estimate that the effect obtained is caused by the partial damping of the loading force due to the elastic component of the polymer.
Enamel Conditioning Effect on Hybridisation of Resin Modiffied Glass Ionomer-Based into Preventive Sealing
Authors: Saveanu Catalina Iulia , Anistoroaei Daniela , Saveanu Alexandra Ecaterina , Dragos Oana , Golovcencu Loredana
Published: January 2020

Disadvantages of diacrilic composite resins and glass ionomers cements have stimulated research to develop hybrid materials to eliminate the downsides and take advantage of their benefits. The purpose of this study was three-dimensional analysis of a flux material with a resin-modified glass ionomer (RMGI) cement in preventive sealing by two techniques of enamel substrate approach, respectively, with acidic conditioning with 37% orthophosphoric acid and free. The best results were observed in the RMGI when no substrate conditioning was performed.
Influence of Dental Humidity on Marginal Adaptation of Biodentine Restorations
Authors: Iovan Gianina , Solomon Sorina , Stoleriu Simona , Ghiorghe Angela Cristina , Nica Irina , Taraboanta Ionut , Andrian Sorin
Published: January 2020

Biodentine is a tricalcium silicate cement used as a dentin replacement in restorative dentistry. The aim of this study was to assess the influence of cavity moisture on the immediate sealing and morphology of the interface between Biodentine and the dental tissues. 20 class II cavities were prepared in extracted teeth. 10 cavities were dried using the air spray before restoring with Biodentine and 10 cavities were preserved moist for the restorative procedure. The teeth were subjected to a microleakage test and then the axial sections were observed under optical microscope and scanning electron microscope. In most situations Biodentine provided an immediate good marginal sealing and a tide contact with adjacent tissues in both occlusal and cervical margins which did not seem to be influenced by the moisture of the dental supporting tissues.
Development of a New Fiberglass Reinforced Composite for Computer Aided Design - Computer Aided Manufacturing Applications in Dentistry
Authors: Varvara Mihai , Stiufiuc Rares , Toma Valentin , Culic Carina , Prodan Doina , Simu Meda , Gasparik Cristina , Mesaros Anca , Grecu Alexandru , Burde Alexandru , Dudea Diana , Culic Bogdan
Published: January 2020

The aim of this work was the development of a series of glass fiber reinforced composites (FRCs) for CAD/CAM applications in dentistry and the characterization of their structure by SEM, Raman and FTIR spectroscopy. A selection of 2 different types of resins (R1 composed from 25%Bis-GMA, 40%UEDMA, 35% DMTEG and R2 composed from 65%Bis-GMA, 35% DMTEG) with 2 different types of hybrid filler (F1 with 42% quartz, 42% radiopaque glass and 16 % hydroxyapatite and F2 with 90% quartz and 10% colloidal silica) and 3 different types of E type fiber glass geometries (veil 30g/m2, twill 163g/m2 and textile 300g/m2) in 4, 6, 8 and 10 layers were used in this in vitro study. Raman analysis, showed a powerful interaction between the polymer and the fiber glass. FTIR and SEM data revealed that the different fiber glass geometries were well incorporated inside the resin, resulting an acceptable homogeneity. Within the limitation of this study, it is possible to achieve a fiber glass reinforced composite for the use of CAD/CAM technology. Further investigation must be done in order to test all the properties of the new material.
Polymeric Biomaterials with Complimentary Role in Joint Endoprosthesis. II. Compositional and morpho-structural analysis
Authors: Mihailescu Dan , Mihai Dana Nicoleta , Savin Liliana , Vasiliu Lavinia , Grigorescu Victor , Patrascu Alexandru , Popa Marcel Ionel
Published: January 2020

Successfully used in bone surgery for more than 65 years, self-hardening organic cements (CCOs), in particular acrylic cements, are today, the most advanced complementary biomaterials used in articular endoprosthesis. One of the strategies for obtaining of performing anchorage of artificial implants is to develop new acrylic cements with improved physical, chemical and biomechanical characteristics. The aim of this paper was to identify the compositional and morpho-structural changes of acrylic cements induced by the composition of the liquid phase of the material. Such changes influence the potential to generate the physical bonds responsible for fixation and stabilization of endoprosthesis. The samples studied had different compositions due to the mixture of acrylic monomers, methyl methacrylate (MMA) and butyl acrylate (BuA) in the liquid component of cement. The MMA / BuA ratio varied between 1/0 v / v and 1/4 v / v. Changes in the composition and morphology of cement samples have been highlighted by ESCA (Electron Spectroscopy for Chemical Analysis), EDX (Energy-Dispersive X-ray Spectroscopy), IR spectroscopy and SEM images. The obtained data show that minor changes in cement composition can significantly influence morpho-structural characteristics such as pore size and their distribution in the mass of fixing material.
Composite Materials Fabricated of Amorphous and Nanocrystalline Metallic Powders
Authors: Codrean Cosmin , Cosma Cristian , ToȘa Dacian , Buzdugan DragoȘ , Dume Adrian Ilie
Published: January 2020

The bulk metallic glasses composites are a new class of bulk metallic glasses (BMGs), containing an amorphous metal matrix and reinforcing materials of metallic or ceramic nature in order to obtaining the desired combination of mechanical properties including strength, hardness, ductility and toughness. Composite materials of cylindrical form with the diameter of 10 mm and 5 mm in height were successfully prepared by hot-pressing of Zr - based glassy alloy powder and Fe - based nanocrystalline alloy powder in different volume fraction. The samples obtained were structural investigated by scanning electron microscopy and X-Ray diffraction and mechanically characterized by hardness and compression tests. It was found that increasing the volume ratio of the Fe-based nanocrystalline alloy up to a certain value leads to an increase in hardness and mechanical compressive strength.
Effect of Local Heating on the Mechanical Characteristics of Repaired Automotive Panels
Authors: Navodariu Nicolae , Branzei Mihai , Ciocoiu Robert , Ciuca Ion , Coman Razvan , Raiciu Anca D. , Semenescu Augustin , Antoniac Iulian , Gradinaru Sebastian , Cristescu Ioan
Published: January 2020

Flame straightening is a technology process used to eliminate deformations. This method relies on local heating of the material to correct geometry or damaged parts. In the local automobile services its main use is for repairs of less critical deformed components. The maximum temperature and thermal gradient, heating time, cooling rate and number of heating cycles affect the mechanical properties since local heating can alter material microstructure. The aim of this research was to determine the mechanical characteristics of thin steel plates repaired by local heating associated with plastic deformation (similar to hot working) and cold straightening (similar to local cold working) for automotive side and door panels made of structural steel. Thin sheet plates, 0.9mm thickness, were deformed by impact and repaired by local heating using the flame and induction heating then plastically deformed while hot as well as straightened without heating. The heat repaired samples were studied by light microscopy to determine microstructure change and samples were tensile tested to determine their mechanical characteristics. Local excessive grain growth generates anisotropy, the assembly behaves as a composite material with regions that show significant plastic deformations while others little or no deformations at al. Without procedures adjusted to each material repairs involving heating are to be avoided, cold working should be employed when replacement is not possible.
Comparative Study on Two Methods Used in Obtaining 3D Printed Dental Models
Authors: Pantea Mihaela , Ciocoiu Robert , Tancu Ana Maria Cristina , Nină Daniela-Mădălina , Petre Alexandru , Antoniac Iulian Vasile , Melescanu-Imre Marina
Published: January 2020

The purpose of this study was to assess the accuracy of two 3D printed dental models manufactured after intraoral/IO and extraoral/EO scanning. A dental study model (KaVo Dental GmbH/Germany) was used as a reference for this research; this model was scanned with an industrial scanner (XT H 225 ST/Industrial CT scan/Nikon Metrology Inc./U.S.A.) and a reference STL file was generated (coded M1). Two 3D printed models (Form2/FormLabs Inc./U.S.A.) were produced via IO scanning (TRIOS 3 Battery Cart/3 Shape/Denmark), respectively via EO scanning (Swing Dental Scanner/Dof Inc./South Korea) of the reference dental model. The 3D printed models obtained were scanned with the industrial scanner, resulting in other two STL files (coded M2, respectively M3). All the STL files obtained (reference M1; M2; M3) were compared in pairs, using a 3D analysis software. Good results were achieved in obtaining 3D printed dental models via IO or EO scanning, yet, the 3D printed dental model obtained via IO scanning (M3) showed slightly improved dimensional compatibility with the reference model (M1) in comparison with the 3D printed dental model manufactured via EO scanning (M2).
The Use of Polyamide Slaklines in Evaluating the Moving Speed in the Dynamic Balance and the Effort Capacity During the Education through Adventure Programs
Authors: Stoica Leonard , Badau Dana
Published: January 2020

Our study�s goal was to underline the differences between the girls� and the boys� representative in terms of age, in what concerns the moving speed and the effort perception during the dynamic balance when walking on the slackline throughout the activities specific for the Development through Education and Adventure (DEA). The results have shown the fact that the boys have a better speed movement on the slackline rather than the girls, allowing us to conclude that the boys� dynamic balance is superior to the girls� balance on both studied age categories. Perceiving the physical effort through heart rate is different according to age category when walking on the slackline for the groups of the study.
Tensile Behaviour of Fabric Reinforced Plies
Authors: Capatina Ana , Cojan Adrian , Bria Vasile , Circiumaru Adrian , Birsan Iulian-Gabriel
Published: January 2020

Nowadays world is exposing a continuous spreading of composites applications and, as a consequence an enforcement of scientist efforts toward such materials design, testing and modelling. Since polymer reinforced materials are covering a huge area of applications it is obvious that the researchers interest is oriented to these materials study in all its aspects. Fabric reinforced polymers represent a very attractive solution from the manufacturers� point of view, especially in the case of thermoset polymers where the lay-up method is the most used to form composites. This study is about tensile behavior of lamina or plies of thermoset matrix fabric reinforced materials. The aim of the study is to determine the role of the matrix and the role of fabric (fibers type, specific weight) on the tensile response to gather valuable information regarding the design of layered materials.
Research Regarding the Evolution of Friction Coefficient in a Friction Torque Like a Plastic Material / Steel for Different Parameters
Authors: Petre Ivona Camelia , Enescu Maria Cristiana , Stoian Elena Valentina
Published: January 2020

Explaining the phenomena occurring at the level of relative friction surfaces has become increasingly complex and often contradictory. Research over time has shown that the friction coefficient for a friction coupler is not a constant magnitude, as Amonton-Coulomb has stated, its values being dependent on a multitude of factors (normal load, slip rate, the nature of the material, the state of lubrication, etc.). The laws of the two are considered to be valid only under conditions of dry rubbing and elastic deformation of the surfaces in contact. The present paper proposes in the first part a study on the theoretical expression of the coefficient of friction. The experimental part of the paper highlights the variation of the coefficient of friction with the speed, loading and processing of the contact surface. It was made on a tribological stand of pin / disc type, and the coupler used was polymeric material called Turcit (for disc) / general purpose steel (for pine).
Thermomechanical Analysis of ERTALON 4.6 Polyamide Used in High Thermal Shock Systems
Authors: Nicola Iulian , Todirica Cornel , Plesa Cornel , Predoi Cristian , Sava Alin-Constantin
Published: January 2020

The paper presents an analysis regarding the use of ERTALON 4.6 polyamide in high thermal shock systems. The behavior of ERTALON 4.6 polyamide mounted on high thermal shock systems was studied using high speed thermal imaging cameras. In the same time its mechanical proprieties were studied with the purpose to determine if it can withstand the stresses that occur during rifle firings.
Mineral Oil versus Vegetable Oil as Electroinsulating Fluids in Contact with Coating LacquersA thermochemical stability study
Authors: Lingvay Iosif , Circiumaru Gabriela , Voina Andreea , Bors Adriana-Mariana
Published: January 2020

The thermochemical stability of a MOL (mineral oil) electroinsulating mineral oil was studied by the gas chromatography technique, compared with a Voil (vegetable oil) electroinsulating fluid based on natural esters (oil), exposed to a longer (1000 hours) thermal treatment (110 � 5 �C) in contact with the core transformer plate (silicon steel sheet) both blank and covered by immersion with three different types of lacquers (L-G epoxide, L-528 alkyl epoxy-melamine copolymer and L-S polyurethane). Experimentally it was noted that during the thermal treatment applied and in contact with the silicon steel sheet, the investigated oils have produced mainly C2H4, CH4 and H2. The total amount of flammable gases formed in Voil (vegetable oil) is about 7.5 time lower than in MOL. It has also been found that the lacquer coating of the silicon steel sheet does not change the mechanism of gas formation processes in the investigated oils, as well as the fact that the oxygen content of the investigated oils decreases monotonously during the thermal treatment applied due to either the formation of CO2 and CO and the oxidation processes of investigated lacquers.
Study on the Behaviour of the Luting Cement for Aesthetic Inlays
Authors: Vitalariu Anca , Tatarciuc Monica , Luca Odette , Holban-Cioloca Catalina , Nicolaiciuc Ovidiu , Diaconu-Popa Diana
Published: January 2020

The clinical success of any indirect prosthodontic restoration is strongly related, among other numerous factors, to the fixing procedure. The technological deficiencies into the inlay cementation lead to defects, either in depth or on surface, which often cause failures. The longevity of inlays depends, to a large extent, on the quality of the dental-prosthetic joint. This marginal adaptation is influenced by the thickness and the type of the luting cement. The aim of this study is a comparative analysis on the behavior of the luting cement for composite resin and ceramic inlays in two different solutions: ANFOR-type artificial saliva and a 20% citric acid solution. Fixing composites are the material of choice for works with high aesthetic potential, our study revealing that their depreciation and alteration is reduced, even in aggressive environments. Cementation seems to be the most critical step, and its long-term success relies on adherence to the clinical protocols.
TECENDO CAMINHOS, OCUPAÇÕES E PERCEPÇÕES:
Authors: Tavares Mendes Froes Lívia
Published: January 2020

Este texto aborda a mobilidade a partir das perspectivas de trabalhadores rurais temporários de Rio Pardo de Minas, norte do estado de Minas Gerais. Baseada em pesquisa desenvolvida juntamente com esses trabalhadores, a análise apresentada considera a diversidade de experiências tendo em vista as distintas faixas etárias, estado civil, modos de assalariamento, destinação do rendimento obtido, e os modos de percepção e de sentimento quanto ao período em que os trabalhadores estão distantes das famílias. A prática do deslocamento é compreendida não somente enquanto um meio para assalariamento, mas enquanto experiência que possui um valor em si, constituinte de aprendizados e habilidades valorizadas positivamente nas redes de relações que estabelecem.
RESISTIENDO EL EXTRACTIVISMO:
Authors: Llano Arias Valeria
Published: January 2020

Este artículo presenta el estudio de caso de un movimiento en contra de la minería de oro a cielo abierto en el noroeste de Colombia. El artículo reflexiona sobre las prácticas de comunicación y la apertura de espacios para la participación democrática y cómo estas han permitido abrir un debate público sobre las implicaciones sociales, ambientales, políticas y económicas de proyectos mineros e hidroeléctricos. El artículo retoma los enfoques de comunicación participativa y pública, la noción de ciudadanía activa, y teoría de los nuevos movimientos sociales, teniendo como base los datos del trabajo de campo realizado en Colombia durante cinco meses como parte de mi doctorado, así como en literatura y experiencias personales y profesionales en el movimiento del agua en Colombia. El marco teórico subyacente a la metodología de mi estudio de doctorado se basa en la Investigación Acción Participativa y etnografía.