bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Crack Propagation and Charpy Impact Properties in Armor Steel Welds
Authors: Cabrilo Aleksandar , Cvetinov Miroslav
Published: January 2020

The process of welding armor steel is a complex process because of possible welding faults, appearing in the weld metal zone in the form of cracks and pores. Austenitic filler material is traditionally used for welding armor steels. For heavy structural engineering such as armored military vehicles, which are frequently under the effect of dynamic load, it is important to know the dynamic properties of the most sensitive area of welded joints, the weld metal zone. Due to a significant interest in quantification of material resistance to crack initiation and propagation, the fatigue crack growth rate was measured in the welded metal zone, while the resistance to crack growth in the weld metal was tested by the amount of austenite transformed into martensite. Accordingly, the threshold stress concentration factor was 10 MPa m1/2. XRD spectral analysis revealed direct transformation of g - austenite into a� -martensite.
Structural Analysis of Fragments of the Broken Coat of a Cylinder which Led to the Dismantling of a Combustion Engine
Authors: Potecasu Florentina , Bordei Marian , Sandu Ion
Published: January 2020

The paper presents the structural analysis of cast iron fragments from the cylinder coat of a combustion engine, as a result of the broken down through explosion. Initially, determinations of the chemical composition were made and it was found that although the cast iron had the carbon content imposed. As a result, detailed microstructural analyzes were made regarding the shape, size and distribution of graphite in the cast iron as well as for the identification of structural constituents and constitutive phases. The same investigations were carried out on samples taken from a cylinder coat with a good functioning for comparison (blank samples). The metallographic study revealed characteristics of inappropriate graphite separations (graphite type B, D, E) and areas with specific structural constituents to the mottled cast iron that can cause breakage of the cylinder coat and excessive wear of the segments.
Comparative Studies on the UV Radiations Resistance of Some Painting Materials
Authors: Rus Traian , Lingvay Iosif , Caramitu Alina Ruxana , Bors Adriana Mariana , Vaireanu Danut Ionel
Published: January 2020

UV radiation has a long-term effect on the durability of anti-corrosive coatings applied by painting, generating conditions for accelerated localized corrosion of the protected metallic structure with adverse effects on operational safety. This paper presents a comparative study of the behavior of some painting materials ageing by exposure to UV radiation relevant by the investigation of dielectric behavior using dielectric spectroscopy in conjunction with the thermal stability investigated by coupled techniques of thermal analysis. From a practical point of view, the UV radiation behavior of two materials based on epoxy resins and polyurethane resin used as paints for protective decorative coatings was studied. The results of experimental investigations have shown that in the aging process of the studied painting materials there is a direct correlation between the evolution of the maximum temperature characteristic of the first thermooxidation process and the evolution of the dielectric performances (dielectric loss - tgd).
Ultrafiltration of Aqueous Solutions of Food Dye Using Polymeric Membranes Prepared with Surfactants
Authors: Popa George Alexandru , Enache (Popa) Daniela Florentina , Tanczos Szidonia Katalin , Ciocanea Adrian
Published: January 2020

The objective of the study is the low-pressure membrane process for treating aqueous solutions containing synthetic food dye (E104 - quinoline yellow). Dye concentration used was 10% (equivalent to 100g/m3). The pressures used in the ultrafiltration process were 0.1, 0.2 and 0.3 MPa. Experiments were performed in dead - end instalations in which the effectiveness of the polysulfone - alkylbenzyldimethylammonium chloride (PSU-ABDMA) and polysulfone - N-dodecylpyridinium chloride (PSU - NDPCl) were tested. The efficiency of these membranes has been proved by calculating the permeate flow and the retention. Analyzing the experimental data, it was found that for the polysulfone-alkylbenzyldimethylammonium chloride composite membrane the degree of retention is completely different, with high values being obtained for low pressures and low values for high pressures used.
Study of Marginal Microleakage in Root Caries Restored with Resin Composites, Giomers and Glass Ionomer Cements
Authors: Nazem Dawod , Biclesanu Cornelia Florentina , Paluta Doina , Manea Stefan , Banita Monica , Hancu Violeta , Florescu Anamaria
Published: January 2020

Root decay is a complex and multifactorial disease. The aim of this study is to assess in vitro the sealing capacity of common aesthetic materials used to restore root caries as well as the size of the hybrid layer formed by SE-1 step vs 2-step ER adhesive techniques. For this study, 45 extracted teeth were used. After cleaning, near the enamel-cement junction, but at the level of the cementum, cavities were prepared and restored with resin composite, giomer and glass-ionomer cements. The teeth were covered with nail polish leaving uncovered the restoration area and 2mm around it; teeth were kept for 24 h , in 2% methylene blue. To assess the degree of marginal adaptation, SEM analysis was further performed. The association of 2-step ER adhesive system with giomers and resin composite shows the maximum adhesion efficiency by forming a uniform, thick layer and dentinal tubules obliteration compared to SE-1 step adhesive system associated with the same restoration materials.
Evolution of the Plasticity of Some Low Carbon Steels, Subjected to Directed Cooling from High-temperature
Authors: Papadatu Carmen Penelopi , Sandu Ioan Gabriel , Bordei Marian , Sandu Andrei Victor
Published: January 2020

An important influence factor for the plasticity of the low carbon steels is the cooling speed value after heating treatment. It is important to be chooses the optimal cooling regime for these materials because the steels have been laminated at high temperature or, the steels have been heated at high temperature after lamination process. There were considered two groups of samples of two low carbon steels, each group had eight samples. Three different mediums for directing of the cooling process were considered and the properties of the steels have been modified. After an experimental program, the values obtained were used to determine the variation between these variables corresponding to two kinds of steels (coded: Steel 1 and Steel 2).
Biomaterials used in Reduction and Fixation of Unstable Fractures of the Zygomaticomaxillary Complex
Authors: Budacu Cristian , Nemtoi Alexandru , Constantin Mihai , Martu Marius Cristian , Haba Danisia
Published: January 2020

This study evaluated a series of cases of fracture in the zygomaticomaxillary complex with displacement of the fractured segment which were evaluated before and after treatment with cone beam CT. The treatment perfomed was represented by titanium micro-plates and screws. The study sample which consist of 25 patients of both genders with fractures in the zygomaticomaxillary bones. After clinical examination to arrive at correct diagnosis and treatment plan, each patient was subjected to 2D and 3D reconstruction using cone beam CT. Reffering to the type of treatment was evaluated the procces of bone remodelling and also the osseointegration process of the titanium micro-plates and screws used for reduction and fixation of the fractures. The treatment performed for all patients was reduction and fixation with titanium micro-plates which were osseointegrated partially in 45 % of patients and 3 screws were not osseointegrated.
Analytical Methods and Finite Element Method Computation The dental - periodontal tissues response
Authors: Bica Cristina , Martha Krisztina , Bica Dorin , Esianu Daniela , Matei Madalina Nicoleta
Published: January 2020

The study of the biomechanical behaviour of dental-periodontal structures during orthodontic movement has been carried out on the basis of the analysis of values of equivalent stress following Von Mises theory, of the stress after the direction of the sz vertical force, which constitutes the essential component of the Von Mises equivalent stress, as well as on the basis of registering the deformities on the tooth axis. The processes of implementation, modelling, calculation and interpretation, using FEM, involved the following steps: defining the geometry and the structure of the model under analysis; meshing the geometry of the structure; connecting the nodal elements; defining the limit conditions and restrictions; loading the created model with vertical forces of different intensities; solving the equation system, having as unknowns in the nodes the following: movement, tension, tension on the spatial coordinates, Von Mises stress. We simulated the orthodontic intrusion through the application of some vertical forces with different intensities and on structures with alveolar bone loss. The tension values in the tooth axis vary in direct proportion to the level of resorption of the alveolar bone, but the decisive element is the numerical value of the applied force, and not the absorption level.
Clinical Outcomes in Implant-Supported Full-Arch Fixed Prosthesis Utilizing Pressed Composite Restorations
Authors: Mihali Sorin Gheorghe , Bratu Emanuel Adrian
Published: January 2020

The author wants to evaluate the clinical advantages and limitations of the composite pressed on metal framework for full-arch implant-supported fixed prosthesis in comparing with dental ceramic restorations. A total of thirty-two edentulous arches were restored. All complications were recorded at each follow-up visit up to 1 year after insertion. No complications were reported on pressed composite restoration. Complications were found in the ceramic restorations like chipping or fracture of the ceramic veneer. The composite pressed restorations are a treatment option for full arch restorations over implants, showing a better success rate in the present study in comparing with ceramic restorations.
Obtaining and Characterization of a Polyurethane Carrier Used for Eugenol as a Possible Remedy in Oral Therapies
Authors: Popa Zoran , Rusu Laura Cristina , Susan Razvan , Pinzaru Iulia , Ardelean Elena , Borcan Florin , Voicu Mirela , Sas Ioana Tuta , Lazureanu Ramona Amina Popovici Voichita
Published: January 2020

The cloves are antiseptic, antiparasitic, antibacterial, antifungal, antiviral, anesthetic, analgesic, anti-inflammatory, tonic, carminative, anti-ulcer, antithrombotic, antioxidant and anti-cancerous. They contain eugenol, tannins and flavonoids that also help to strengthen the vein wall. This paper presents the obtaining and the characterization of a polyurethane drug delivery system which can be used for the transmembrane transport of eugenol in oral therapies. The products were analyzed by pH and solubility measurements, thermal decomposition and zetasizer tests and they were applied on mice skin to evaluate their harmfulness. The results suggest that were obtained neutral pH structures with low solubility and a good thermal stability, with sizes between 241 and 289 nm and no toxicity effect was found in the case of studied samples.
Ageing of Some Painting Materials Subjected to Thermal Treatment in Natural Esters
Authors: Rus Traian , Caramitu Alina Ruxana , Ungureanu Livia Carmen , Marinescu Virgil , Bors Adriana Mariana , Vaireanu Danut Ionel
Published: January 2020

This paper describes the evaluation of the aging process of some polymeric painting materials subjected to a thermal treatment in electro insulating fluids, based on natural esters (vegetable oils). The paint layers surface morphology was comparatively characterized by FESEM technique, prior to the exposure, and after 1000 h of exposure to vegetable oil, heated at 130oC. The results show a substantial increase in the pulling resistances for all the painting materials subjected to this investigation, especially in the presence of the Kraft insulating paper and copper foil (inserted compulsory to emulate the actual working environment), due to an increase in the painting material adhesion, as well as an increase of the tensile strength of the paint layer. These findings may open new theoretical and practical research prospects, particularly in the field of preliminary treatments for materials used for heavy duty industrial transformers.
Recurrence Rates and Mesh Shrinkage After Polypropylene vs. Polyester Mesh Hernia Repair in Complicated Hernias
Authors: Socea Bogdan , Socea Laura Ileana , Bratu Ovidiu Gabriel , Mastalier Bogdan , Dimitriu Mihai , Carap Alexandru , Constantin Vlad Denis
Published: January 2020

Prosthetic mesh implants in hernia repair are frequently used based on the fact that lower recurrence rates are detected compared to anatomic repair. In latest years, researchers tried to answer weather there is an ideal mesh material for abdominal hernia repair. The studies tried to compare resistance, bio-tolerance, rates of recurrence and infection of several materials used in alloplasty. The results are far from pointing an unique ideal chemical structure of mesh. In our study, we compared the results of a cohort of 265 patients operated in 2010 and 2011 in our clinic for complicated abdominal incisional hernias. We compared the results of polypropylene mesh vs. polyester. Polypropylene mesh proved significantly better for preventing hernia recurrence and showed a lower shrinkage rate.
Propagation of a Crack in a Composite Plate
Authors: Iacob Ionel , Chirica Ionel , Beznea Elena Felicia
Published: January 2020

In this paper, a model of a composite plate with a central elliptical cut-out and with an initial fissure was subjected to a tension load in the finite element method (FEM) software Abaqus to observe the propagation of that crack during a certain amount of time that elapsed in the FEM analysis. Due to symmetry, only half of the plate was modeled, as a shell, and the extended finite element method (XFEM) was used for the crack. The material properties that were assigned to the plate were taken from the database of the Ansys Mechanical software. In the vicinity of the crack a finer mesh was applied to be able to better observe the evolution of the fissure and the changes of the Von Misses stress graphs for each time step of the analysis.
Laser hardening influence of metal surfaces
Authors: Rusanescu Carmen Otilia , Rusanescu Marin , Jinescu Cosmin , Biris Sorin Stefan
Published: January 2020

In this paper we analyze the influence of the number of laser pulses on the hardness of the metal. We have shown that the hardness increases with the number of laser pulses due to the increase in the probe surface temperature, especially by increasing the superficial absorption of laser radiation. Optical microscopy was analyzed by the metallographic aspects of the target in OLT 65, Al, Cu, laser irradiated.
Thermooxidative Behavior of Some Paint Materials in Natural Ester Based Electro-insulating Fluid
Authors: Lungulescu Eduard Marius , Lingvay Iosif , Ungureanu Livia Carmen , Rus Traian , Bors Adriana Mariana
Published: January 2020

ATR / FTIR and DSC techniques have been used to evaluate the thermal stability of some ageing paint materials by heat treatment while immersion in natural ester-based electro-insulating oil. Experimental determinations have highlighted the fact that the investigated paint materials (epoxy resins) have a high oxygen affinity and thus, in closed systems (such as power transformers), they oxidize before coming into contact with the transformer oil. This behavior indicates that the paint layer (suitably chosen) applied on the inside of the transformer vat functions as an antioxidant and results in increasing the thermal stability of the oil.
Comparative Study on the Use of Polypropylene Mesh in the Surgical Treatment of Patients with Strangulated or Uncomplicated Incisional Hernias
Authors: Halmaciu Ioana , Suciu Bogdan Andrei , Fodor Decebal , Godja Dumitru , Trambitas Cristian , Vunvulea Vlad , Brinzaniuc Klara , Molnar Calin
Published: January 2020

Incisional hernias affects approximately 10-20% of patients with history of abdominal surgery. The purpose of this study was to examine the tissue integration of the polypropylene mesh in patients operated for strangulated incisional hernias to those operated for uncomplicated incisional hernias. For this purpose, we introduced 218 patients with surgical treatment of the incisional hernia with polypropylene mesh. The total number of patients studied was divided into 2 lots: group A consisting of 189 patients with uncomplicated incisional hernia and group B of 29 patients with strangulated incisional hernia. We studied separately the local postoperative complications in the two groups (hematomas, seromas, abdominal wall infections). Although the number of local postoperative complications was higher for group B, the differences were statistically significant only for the incidence of abdominal wall infections. Although the use of the polypropylene mesh in the surgical treatment of strangulated incisional hernias predisposes to a higher risk of local postoperative complications compared to its use in the surgical treatment of the uncomplicated incisional hernias, its use in the surgical treatment of the strangulated incisional hernias is beneficial.
Design of ABS Plastic Components through FDM Process for the Quick Replacement of Outworn Parts in a Technological Flow
Authors: Pascu Nicoleta Elisabeta , Dobrescu Tiberiu Gabriel , Balan Emilia , Jiga Gabriel , Adir Victor
Published: January 2020

The paper shows the importance of designing an ABS (Acrylonitrile-Butadiene-Styrene) plastic part which will be produced using FDM (Fused Deposition Modeling) technology; it is obtained a product with the same characteristics provided by the operating guide book. Thus, this solution combines both the capacity of the designer as well as the applied technology and can produce similar or improved plastic components, at the same time maintaining the functional characteristics of the work piece. This paper is a plea for the application of 3D printing using FDM technology for manufacturing components (spare parts) out of production, because the technological systems users no longer have other solutions available for replacing outworn plastic parts. 3D printing using FDM technology is a fast option for replacing outworn components, the modeling, simulation and printing time being shorter than the purchase time of a new subassembly or assembly that has been remanufactured and modernized.
Execution of Plastic Parts Using 3D Scanners and 3D Printers
Authors: Bucuresteanu Anca , Prodan Dan , Motomancea Adrian
Published: January 2020

In this paper, the authors show a part of research works performed on the use of 3D scanners and 3D printers to execute plastic parts with complex surfaces. 3D scanning allows copying of certain surfaces in our environment, based on existing models. Scanned models may represent various objects, made of a wide range of materials: metals, ceramics, fabrics, plastics, leather, organic materials etc. [1]. This paper shows the results achieved using a scanner and a common and affordable - low-price - printer. 3D scanners and printers allow execution of clones of certain parts with irregular surfaces.
Influence of the Double Bond LDH Clay on the Exfoliation / Intercalation Mechanism of Polyacrylamide Nanocomposite Hydrogels
Authors: Radu Ionut Cristian , Vasile Eugeniu , Damian Celina Maria , Iovu Horia , Stanescu Paul Octavian , Zaharia Catalin
Published: January 2020

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.
Assessment of Paint Layers Quality 1. Field investigations on a railway bridge
Authors: Varga Emese , Fortuna Laszlo , Lingvay Daniel , Bors Adriana Mariana , (Butoi) Nicula Nicoleta Oana , Lingvay Iosif
Published: January 2020

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.
Nonlinear Behaviors in Gene Therapy Theoretical and experimental aspects
Authors: Cioca Gabriela , Pinteala Mariana , Bacaita Elena Simona , Oprea Iuliana , Tanasa Irina Crumpei , Volovat Simona Ruxandra , Dragan Valentin Stelian , Trocaru Sorin , Anton Carmen
Published: January 2020

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.
Fracture Resistance of CAD/CAM Versus Traditional Interim Fixed Dental Prostheses
Authors: Pop Daniel Alexandru , Malaescu R. , Marsavina Liviu , Hosszu Tiberiu , Rotar Raul , Goguta Luciana , Duma Virgil Florin , Negrutiu Meda Lavinia , Sinescu Cosmin , Jivanescu Anca
Published: January 2020

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.
Influence of Packaging and Stability Test Assessment of an Anti-aging Cosmetic Cream
Authors: Juncan Anca Maria , Rus Luca Liviu
Published: January 2020

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.
Light Transmittance by Organic Eyeglass Lenses According to their Class
Authors: Jez Kinga , Nabialek Marcin , Gruszka Konrad , Deka Michal , Letkiewicz Slawomir , Jez Bartlomiej
Published: January 2020

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.
Tribological Evolution of the Superficial Layer and the Effects of the Magnetic Field to a Non- conventional Treated Steel, During Wear Tests
Authors: Papadatu Carmen Penelopi , Sandu Andrei Victor , Bordei Marian , Sandu Ioan Gabriel , Ciortan Sorin
Published: January 2020

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.
Variability of Mechanical Properties of Collagen Membranes used in Dentistry
Authors: Santo Loredana , Quadrini Fabrizio , Bellisario Denise , Polimeni Antonella , Santarsiero Anna
Published: January 2020

The aim of this study is proposing a combination of measurements to assess the functional variability of collagen membranes used in Guided Bone Regeneration (GBR) and Guided Tissue Regeneration (GTR) techniques. As far as clinical applications are concerned, a proper qualification is critical when deciding, among commercially available collagen membranes, upon the most appropriate one for each specific clinical case. Two commercially available collagen membranes, namely Collprotect� and Jason�, were considered for the experimentation. After thickness and density measurements, the quasi-static behavior was studied for both membranes by means of conventional mechanical tests, i.e. tear and tensile tests, whereas their time-dependent behavior was evaluated by means of stress relaxation tests and dynamic mechanical analysis. Collagen membranes showed an elevated among samples variability. The variability within the same kind of membrane is of the same order of magnitude of the between membrane kinds variability. All the membranes showed strong time dependence both in stress relaxation and in dynamic mechanical tests. This fact should be taken under consideration for the membrane final application.
Additive Manufacturing and Synthetic Polymers for Bone Reconstruction in the Maxillofacial Region
Authors: Cristache Corina Marilena , Grosu Alexandra Raluca , Cristache Gheorghe , Didilescu Andreea Cristiana , Totu Eugenia Eftimie
Published: January 2020

The aim of the present paper is to give an up-to date on computer aided design and manufacturing (CAD/CAM) additive techniques and synthetic polymers for bone reconstruction in the maxillofacial region. Additive manufacturing represents a promising field for future research in bone replacement/regeneration. However, standard guidelines for mimicking clinical environment with the different bone characteristics are strongly required. The rapid prototyping techniques, particularly, bioprinting allows the construct of 3D living functional tissues able to replace, in the near future, large defects caused by tumor excision, trauma, clefts or infections, limiting the autogenous bone graft requirement.
Study Regarding the Compressive Properties of Glass Fiber Reinforced Composites
Authors: Spanu Paulina , Amza Catalin Gheorghe , Abaza Bogdan Felician
Published: January 2020

Compressive strength of the polymeric composites is an important data for design of composite structures and therefore a depth study of this mechanical property is imperative. The mechanical properties of the polymer composites vary in the very large ranges according to the characteristics of the constituents, to their proportions and many other factors. Compressive property and failure mechanism of polymer composite materials reinforced with glass fiber were investigated in this paper. The experimental data for the studied materials were included the compressive strength, strain, poisson�s ratio and modulus. Some of these experimental values could be affected by aberrant errors. This paper also presents an application that removes the experimental data affected by gross errors from the sample of numerical values. The elimination of experimental data affected by gross errors is based on Chauvenet criterion.
Constrained Rotating Hinge Prostheses in Severe Haemophilic Knee Osteoarthritis
Authors: Veringa Vlad , Friedl Wilhelm , Forna Norin , Ivan Andrei , Filip Nina , Puha Bogdan
Published: January 2020

The purpose of this experimental study is to present the design and biomechanical characteristics of cemented total knee prostheses type rotating-hinge RT-PLUS® (Smith and Nephew), as well as to evaluate their use in severe haemophilic knee arthropathy with major bone damage, ligamentous lesions, axial deviations and muscle retractions. We retrospectively evaluated 5 patients with severe haemophilic arthropathy with an average age of 48.5years. The functional results are good, with a significant improvement of range of motion (ROM) and pain relief resulting in a much better life quality. We did not have any stem loosening or any other complications except 2 wound healing problems which were treated successfully. The authors recommend this type of arthroplasty in severe haemophilic knee arthropathy or in any primary knee osteoarthritis with severe bone loss or any kind of ligamentous lesions.
Comparative Study on the Degree of Bacterial Biofilm Formation of Dental Bridges Made from Three Types of Materials
Authors: Bolat Maria , Bosinceanu Dana Gabriela , Sandu Ioan Gabriel , Bosinceanu Dan Nicolae , Surlari Zinovia , Balcos Carina , Solomon Oleg , Vitalariu Anca
Published: January 2020

The aim of this study was to compare the biofilm formation on three types of dental crown materials using adenosine triphosphate (ATP) driven bioluminescence as an innovative tool for the rapid chairside enumeration of oral bacteria and assessment of oral hygiene. The study group included 60 patients with fixed prosthodontics, made of three types of dental crown materials (BioHpp - Bredent, Ceramics - VITA VMK Master, and Zirconia - Vita In-Ceram) from which we have collected 60 specimen values using a luciferase-based assay system (system SURE II). The values of ATP were obtained with System SURE II device and statistically analyzed with Anova and Wilcoxon Test. The lowest value was shown for Zirconia, comparing with ceramics and BioHpp, but in time we have seen the increase of ATP for all three dental crown materials.
A Different Aproach of Chronic Obstructive Pulmonary Disease Severity and Plastic Medical Devices Used for Oxygenotherapy
Authors: Tofolean Doina Ecaterina , Popescu Gilda , Arghir Ioan Anton , Frandes Mirela , Fildan Ariadna Petronela
Published: January 2020

A very common questionnaire, used to evaluate the health status of Chronic Obstructive Pulmonary Disease (COPD) patients, COPD assessment test (CAT), was applied to finding correlations between the items of CAT and other tests used in the same category of COPD patients. A sample of 56 male COPD patients, aged between 51 and 74 years, mean 63.86 (�5.55), half of them receiving long-term oxygen therapy, using transparent, hypoallergenic plastic masks or nasal cannulas, answered to CAT mostly choosing single items, statistically significant correlated with the Hospital Anxiety and Depression Scale scores (HADs), like walking up hills and stairs (r = 0.412, p[ 0.01), doing activities at home (r = 0.329, p[ 0.01), confidence leaving my home (r = 0.409, p[ 0.001), sleep (r = 0.277, p[ 0.01), and energy (r = 0.387, p[ 0.01), but CAT item walking up hills and stairs correlated better to 6 min walking distance (6MWD) (r = -0.581, p[ 0.01). The most significant correlations were found between 3 items of CAT as walking up hills and stairs, limitations doing activities at home and confidence leaving home in a most powerful and depression scores and 6MWD.
Synthesis and Characterization of Composite Membranes Based on Carbon Functionalized with Gold Nanoparticles
Authors: Vatui (Moise) Alexandra Georgiana , Valsan Sorina Nicoleta , Fratila Corneliu , Ghita Andreea Nicoleta , Sobetkii Arcadii , Mihaiescu Daniel Cristian , Slobozeanu Anca Elena , Trusca Roxana
Published: January 2020

The purpose of this experimental laboratory work is to obtain composite membranes having carbon and gold nanoparticles in the matrix. Consideration was made of using graphene oxide, a material which, under certain conditions, can generate membranes by a self-assembly process under vacuum in an aqueous or organic medium. The cellulose acetate (CA) - graphene oxide (GO) composite membranes have been functionalized with gold nanoparticles (AuNP) by two technological processes: thermal evaporation and ultrasonic mixing of stable graphene oxide and gold suspensions. The stable suspensions containing gold nanoparticles were obtained by chemical reduction of aqueous solutions of Tetrachloroauric acid trihydrate (HAuCl4) precursors with sodium citrate under high temperature conditions. Dispersibility of carbon nanostructures and precious metal nanoparticles has been studied with a DLS granulometer - Malvern Instruments Zetasizer ZS90. It was determined the mean particle size and Zeta potential function of the suspensions pH. The graphite based membranes were further subjected to various characterizations techniques. It was found that both the surfaces and the cross-sections were functionalized with gold particles. The presence of Au particles was revealed both on the membrane surface and also inside its structure. Hydrophilic tests demonstrate that the membrane filters have potential to be used in various applications.
The Antioxidant Effects of PLGA-based Nanoparticles Loaded with Vitamin E in Rats Treated with Hypercaloric Diet
Authors: Miricescu Daniela , Balan Daniela Gabriela , Radulescu Catalina , Radulescu Radu , Stanescu Iulia-Ioana , Mohora Maria , Virgolici Bogdana , Totan Alexandra , Greabu Maria
Published: January 2020

PLGA (Poli-lactic-co-glycolic acid) nanoparticles (NPs) are curently used as drug delivery systems for many types of drugs including antioxidants such as vitamin E. The main aim of our study was to test the antioxidant effects of PLGA-vitamin E on Wistar male rats. Two groups of Wistar rats received a hypercaloric diet for 21 days: the first group received besides the hypercaloric diet a daily dose of PLGA loaded with vitamin E and the control group received only the hypercaloric diet. Spleen cellular lysate has been used to detect biomarkers of oxidative stress such as malondialdehyde, glutathione, advanced human oxidative protein and vitamin E. After 3 weeks of treatment, statistical significant changes have been detected between the two groups.
Effect of Continuous Micro Reinforcement and Processing Parameters on the Low-Velocity Impact Behaviour of Polymer Composite Materials
Authors: Maier Raluca , Mandoc Andrei , Paraschiv Alexandru , Istrate Marcel
Published: January 2020

Low velocity impact tests were conducted on quasi-isotropic [�45/0/90o]xs laminates under drop weight impact from 0.7m, corresponding to a 30J energy. In this respect modified epoxy blends reinforced with carbon and Kevlar woven fabrics laminates were developed using autoclave technology. The four configurations developed for low velocity impact tests aimed at investigating several aspects like: the effect of fiber type, stacking sequence and mainly technological processing parameters, on the impact performances. The recorded Load-Time curves were plotted and visual inspection, high resolution laser scanner were used to observe the fracture characteristics of the impacted composite laminates. The results obtained showed that for tested configurations, both stacking sequence and processing parameters directly linked to fiber volume fraction, have a strong effect on the impact performances. The amount of absorbed energy, ductility index was calculated for each configuration under study. The results obtained showed that hybrid configuration exhibits lower stiffness and damage initiation energy amount when compared to carbon reinforced configurations. Nevertheless, their damage propagation energy amount and ductility index was the uppermost. This behaviour was already reported previously [1] and is partially attributed to the higher elastic energy absorption of carbon fibers that delays the propagation of delamination, and fiber breakage. Lower tenacity obtained on hybrid laminates was attributed to both lack of resin local rinse saturate and to the intrinsic anisotropy of para-aramid fibers.
Design and Study of Electrochemical Sensors Based on Polymer Inclusion Membranes Containing Polyoxometalates
Authors: Apostu Mihai , Vieriu Madalina , Bibire Nela , Panainte Alina Diana , Tantaru Gladiola
Published: January 2020

Polyoxometalates (POM) are a class of inorganic compounds with various structures and remarkable electrical, magnetic and optical properties. Ion-pair complexes formed with some organic cations have high lipophilicity and they can be used as ionophores for PVC matrix membranes with active recognition function. The present study describes the construction and characterization of selective membrane sensors based on electroactive material incorporated in PVC matrix. They have been employed for the determination of ranitidine and nizatidine by using their complexes with silicotungstic acid as ionophores. The composition of the membrane has been optimized. The linear response range for both sensors was between 10-1-10-5M with quantification limits of 2.83�10-6M for ranitidine and 3.43�10-6M for nizatidine, and a response time shorter than 50 seconds. The new electrodes have been used for the potentiometrical determination of ranitidine and nizatidine in pharmaceutical products.
Microhardness Investigation of Dental Composite Resins Exposed to Corrosive Environment
Authors: Ghiorghe Cristina-Angela , Carlescu Vlad , Topoliceanu Claudiu , Nica Irina , Pancu Galina , Iovan Gianina , Andrian Sorin , Lupu Costin
Published: January 2020

The aim of this study was to evaluate the microhardness Rockwell and Young s modulus of a new nano-hybrid and nano-fill composite resins exposed to corrosive media. The study was performed on two composite resins, one nano-hybrid and one nano-fill, enamel, dentine, translucent, respectively body shade, of which were made 20 samples (25.0 � 0.1 mm lengths, 10.0 � 0.1 mm widths and 3.0 � 0.1 mm thicknesses), which were immersed in mouthwash for 1 minute per day for 10 days, the rest of the time being stored in artificial saliva. Measurements of Rockwell microhardness and Young�s modulus on samples were made between on the first day, after 6 days and 10 days of immersion in mouthwash comparative with 0 day. The results showed that after immersion in the corrosive environment, both materials had the hardness values changed, but medium values of Rockwell microhardness to nano-fill composite resin were higher than nano-hybride. At the nano-hybride composite resin, it was observed that the enamel and clear translucent groups had the mean values increased after the first day of exposure to mouthwash, compared to the dentine group, which showed a higher mean value after 6 days. At the nano-fill composite resin, for the enamel and body groups were obtained the higher values of HRC after 10 days. For the dentine group, after 6 days, Filtek Ultimate showed the same variation as Harmonize dentine shade. Harmonize composite resin showed higher values of Rockwell microhardness and Young�s modulus for all study groups compared to Filtek Ultimate.
Research Regarding Design and Material for an Electrical Car Charger Shell
Authors: Buciuman Catalin Marin , Hancu Liana , Vilau Cristian , Borzan Cristina Stefana Miron
Published: January 2020

In the recent years, the electric vehicles have drawn great attention worldwide as a feasible solution for clean transportation. The charging infrastructure for electric vehicles is expanding throughout the world, encouraged by large investments from the automotive industry, to reduce carbon emissions. The purpose of this paper is to design the shell of an electrical vehicle charger by using polymeric composite materials. The manufacturing technology is proposed and the analysis of the product behaviour during the wind action in extreme conditions is presented. The paper includes studies and research regarding the design, the manufacturing and the simulation for the action of wind upon the product�s walls. The simulations are performed for the actual used material (ordinary sheet steel) and for the proposed composite material in order to compare the results. The composite material seems to be an adequate solution for the electric charger shell.
Evaluation of the Mechanical Properties of the Samples Made by FDM 3D Printing
Authors: Popa Alexandru , Faur Nicolae , Hluscu Mihai , Belin Cosmin
Published: January 2020

Designing a sample to be made by FDM 3D printing is a fundamental problem in further studies related to such printed structures as material properties vary depending on filament orientation and G-code particularities. Samples designed to simulate wall structures inside 3D printed parts have been tested to allow separate evaluation of key components in such parts. Results show a very long plastic region in filaments without imperfections. As filament strands break steps of similar values appear in the reaction force measured by the machine.
Polyethylene Mobile Bearing in Total Knee Arthroplasties. Design, advantages and preliminary results
Authors: Sirbu Paul Dan , Veringa Vlad , Badulescu Oana Viola , Arcana Stefanita , Forna Norin , Scripcaru Andrei , Sirbu Mihnea Theodor , Alexa Ovidiu
Published: January 2020

The purpose of this experimental study is to present the design and biomechanical characteristics of mobile bearing postero-stabilised total knee prosthesis type MC2�- C2F� and to evaluate their use in severe primary knee osteoarthritis. The experimental part was carried out on 20 patients who benefited from mobile bearing postero-stabilised total knee prosthesis type MC2� in University Hospital Sf Spiridon Iasi, Romania. From the radiological point of view there were no mechanical complications in a 3 year follow-up. The functional recovery had a good outcome and patients currently have an active flexion between 70� and 110�, with extension between 0� and -15�. No pain was registered in full weight bearing and in active joint movement.The clinical and radiological outcome at 3 year follow-up is satisfactory and the results convinced the authors that this type of prosthesis is a good option in any primary knee osteoarthritis with no significant bone loss.
Effect of Tooth Brushing on Wear of Microhybrid Composites In vitro experiment
Authors: Dudas Csaba , Szekely Melinda , Gabor Maria Henrietta , Farkas Laszlo Jakab , Dorner Kinga , Nimigean Vanda Roxana , Nimigean Victor , Molnar-Varlam Cristina , Kerekes-Mathe Bernadette
Published: January 2020

Changes in the surface roughness of dental restorative materials after tooth brushing are inevitable. The abrasion is known to increase the possibility of dental plaque accumulation which is responsible for several pathologies of the oral cavity. The aim of this in vitro study was to evaluate the changes of surface roughness of microhybrid composite materials produced by different toothbrushes with and without toothpaste. Forty-eight specimens of two composite materials (Charisma and Super-Cor) were prepared using a silicone template according to the manufacturer�s instructions. Each sample was brushed for eight hours. Each group of specimens was divided in two subgroups: half of the samples were brushed using only distilled water and the other half with a mixture of distilled water and toothpaste (Colgate Total; ratio 1:1). The average roughness value (Ra) of surfaces were measured with profilometer three times: the initial measurement was performed before starting the toothbrush simulation, the second was after 4 hours and the third was after 8 hours of brushing. Three different bristle stiffness toothbrush heads were used (medium sensitive, medium and soft). After collecting all numerical data one-way ANOVA and Friedman tests were performed for statistical analysis. All examined microhybrid composites exhibited changes in surface roughness after the toothbrush simulation. The simulation of toothbrushing without toothpaste, only with water as cleaning substrate, showed at every measurement the lowest values of roughness in all three toothbrush heads. Significantly increase of mean Ra values were observed in both tested composite samples when medium and soft toothbrushes with toothpaste were used. The surface roughness changes of tested microhybrid composites depend on the brushing procedure. The toothpaste has a much greater effect on the abrasion than the type of toothbrush.