bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Study Regarding the Deformation Values of Orthodontic Aligners
Authors: Grigore Adelina , Szuhanek Camelia , Onisei Doina , Cernescu Anghel
Published: January 2020

Orthodontic therapy using aligners is a modern treatment option among adult patients. In order to have an optimal control of the orthodontic resuslts, there is a need for knowing the deformation values that can appear in each type of aligner, the optimal thickness values of the appliances and the needed number of aligners for each case. The deformation values for a 0.2 mm repositioned lower central incisor were measured with the use of some strain gauges applied at this level, after a manual set-up was manufactured. Different orthodontic forces were applied on each aligner in order to compare the deformation value during the dental correction. The thickness values of the aligners that were used for this study were 0.625 mm, 0.75 mm and 1 mm. The 0.625 mm aligner had the lowest deformation value dueto a high elasticity of the material.
Studies Regarding the Efficiency of Grape Tannins Greening Plastics
Authors: Ignat Gabriela , Colibaba Cintia , Costuleanu Carmen Luiza , Moraru Ioan , Vintu Catalin Razvan , Ungureanu George , Bejinariu Costica
Published: January 2020

Grape marc, also known as grape pomace, is one of the most investigated bio-wastes derived mainly from grape skin and seeds, which is produced as a by-product of winemaking on the million-ton scale annually. Presently, the most important high-value use of grape pomace is in the production of oenological tannins, widely-used additives in the food and beverage industry. This article studies the possible use of grape waste in the plastic industry, as request of the consumer for green plastics with regards to environmental impact, and in the case of packaging, to improve the shelf-life and safety of the products contained. 4 white grape varieties and 4 red grape varieties (most cultivated grape varieties in Romania) were taken into study, processed using different technological methods and the spent material (grape skins and seeds) were analysed regarding their total phenolic compounds and total tannins.
Experimental Research on the Triangular Lattice Type Polymer Based Composites Structures for Sandwich Panels Construction
Authors: Durbaca Adrian Costin , Iatan Radu , Durbaca Ion , Dinita Alin , Vasilescu Marius
Published: January 2020

The paper presents experimental results on the mechanical behaviour for a polymer based composite sandwich panel tensile and bending tested, which uses, one by one, a cellular composite core fabricated by additive manufacturing of four different types of polymeric materials: ABS (acrylonitrile butadiene styrene), PC (polycarbonate), PLA (polylactide) and CF (polylactide + 40% carbon fibre), with the thickness of 3 and 5 mm. This research focuses on comparative analysis of the core thickness increase effect on the structure�s strength. Experimental tests carried out on standardized test-pieces with specialized laboratory equipment, are highlighting similar mechanical behaviour and are showing also an increase of composite stiffness with the increase of core thickness, at the same time, the arrangement of the cellular lattice structure has a significant effect on the structural strength.
The Effects of Magnetic Nanoparticles Incorporated in Polyelectrolyte Capsules
Authors: Druga Corneliu , Necula Radu , Cotoros Diana , Miclaus Roxana , Repanovici Angela , Nica Sarah Adriana
Published: January 2020

Most studies and experimental tests performed upon orthopaedic bone cements are related to their use in everyday conditions when usual wears are due to compression and fatigue. The present paper deals with some special situations occurred during the patient�s recovery after the surgery. The recovery activities and motions may induce different types of loads, like tensile, during stretching and relaxation techniques, especially in the joint insertion area. These situations are insufficiently researched, but they represent one of the main concerns of the medical staff involved in recovery and rehabilitation. Besides the study of mechanical properties for these special situations the paper proposes also a thermal analysis during preparation of the polymethylmethacrylate(PMMA) as it can be the trigger of serious health issues (necrosis, blood circulation problems, BCIS, etc.) due to the exothermic polymerization reaction. The monitoring method proposed for the temperatures developed during the polymerization may avoid the aforementioned issues.
Low Molecular Weight Microfibers with Light Sensing Properties
Authors: Bejan Andrei , Peptanariu Dragos , Chiricuta Bogdan , Bicu Elena , Belei Dalila
Published: January 2020

Microfibers were obtained from organic low molecular weight compounds based on heteroaromatic and aromatic rings connected by aliphatic spacers. The obtaining of microfibers was proved by scanning electron microscopy. The deciphering of the mechanism of microfiber formation has been elucidated by X-ray diffraction, infrared spectroscopy, and atomic force microscopy measurements. By exciting with light of different wavelength, florescence microscopy revealed a specific optical response, recommending these materials for light sensing applications.
Macroscopic Examination of Placental Vascularization with a Corrosive Agent in Pregnant Women Diagnosed with Thrombophilia
Authors: Bonte Diana Camelia , Iordache Olivera , Petre Izabella , Craina Marius , Chiriac Veronica Daniela , Stoian Dana , Moleriu Lavinia Cristina , Sisu Alina
Published: January 2020

The normal development of the placenta is a major factor in the fetus s growth and development, whilst the maternal-fetal placental vasculature is essential in this regard. During placentation, there is an ongoing process, which combines angiogenesis with vasculogenesis, as demonstrated by numerous studies, which reveal important roles of various known angiogenic factors, while other studies show the roles of different classes of factors in vascular morphogenesis nonspecific to the placenta. The method used in the case of our study is a standardized method of the Laboratory of Anatomy and Embryology, Victor Babes University of Medicine and Pharmacy, Timişoara, for over 50 years. The making of corrosion concoction followed the recipe of the laboratory using type AGO II plastic substances, differently colored and then subjected to the corrosive action of hydrochloric acid. During the routine check outs all the pregnant woman�s were diagnosed with thrombophilia. The examination of the placental parameters - shape, weight, thickness - is important as a preliminary stage for the study of the placental architecture. The normal placental development remains a major factor in the growth and development of the fetus, and the maternal-fetal placental vasculature is essential in this regard. Placental angiogenesis has a different local component of angiogenesis, found in other anatomical regions.
Evaluations of Two Reinforced Polymers Used as Metal-Free Substructures in Fixed Dental Restorations
Authors: Biris Carmen , Bechir Edwin Sever , Bechir Anamaria , Mola Farah Curt , Badiu Adrian Viorel , Oltean Cristian , Andreescu Claudia , Gioga Cherana
Published: January 2020

The development of new classes of dental materials determined the apparition of reinforced polymers, as BioHPP and Trinia, used for core in non-metallic prosthetic restorations, including in implants non-metallic superstructure. The purpose of the study was to present the results of the comparative clinical trials referring to the use of BioHPP and Trinia resins as core in fixed prosthetic rehabilitation. The researches were performed on 33 patients in which we realized 71 fixed prosthetic restorations. According to the six evaluation criteria used in research, we conducted biannual monitoring meetings over two and half years period for registrations of comparative results in the use of these two reinforced polymers as core. The results of the study demonstrated that both type of these materials exhibit a certain degree of elasticity and presents many advantages, therefore these represent a beneficial acquisition in patients oral health.
Implant Surgery Using Bio-compatible Guides
Authors: Talpos Serban , Hajaj Tareq , Timofte Costin , Rivis Mircea , Streian Felicia , Popa Malina , Sinescu cosmin , Negrutiu Meda Lavinia , Stan Adrian , Zaharia Cristian , Szuhanek Camelia , Ianes Emilia , Pricop Marius
Published: January 2020

Implants and biomaterials used in hard and soft oral tissue augmentation are very complex, but predictable to use nowadays, as the technological advances haven�t skipped this field of medicine. Cases that were impossible to treat with implant retained fixed prosthesis some years ago, have become the daily practice of oral surgeons and dentists around the world. The new user-friendly products, together with simplified protocols, increased the practitioners� predictability and success rate, thus the biomaterial industry took a huge leap forward. As the biomaterial industry keeps developing continuously, making better and safer products, the surgical and prosthetic protocols evolve and change as well. On this matter, the implant placement has become safer, using digital surgical guides. Guided implant placement doesn�t just allow the practitioner place the implant in the patient�s bone, but, moreover, it helps him place it in the correct, 3D, prosthetic position. And, thus, guiding the future bone augmentation and regeneration as well, accordingly. So, the implant placement has shifted from bone-orientated to prosthetic-orientated, offering at the same time a better primary stability for the implants, due to the prior planning. The present clinical study aims to analyze the outcome of the digital guided protocol. Unlike the free-handed surgery, the digital guided surgery allows dentists and oral surgeons to place implants according to the future prosthetic position of the crowns, even in conditions of alveolar ridges with bone resorption. Moreover, it makes possible the �one day implant� concept, the dental technician being able to create the provisional crown/s in advance, knowing precisely the future position of the implant placement. So, at the time of the surgery, the provisional crown is also put in place, guiding the soft and hard tissue healing and also giving the patient a greater satisfaction.
Crystal Structure of Tetrakis(2,2�-bithiophene-5-yl)silane
Authors: (Georgescu) Stoica Elena Bianca , Branger Catherine , Iordache Tanta Verona , Sarbu Andrei , Iovu Horia , Vitrik Oleg B. , Dyshlyuk Anton V. , Brisset Hugues
Published: January 2020

The crystal structure of tetrakis(2,2�-bithiophene-5-yl)silane, C16H10S4Si0.5, has been determined at 293K in the Monoclinic (I2) symmetry. The Si atom has quasi-perfect tetrahedral geometry and bithiophene unit are quasi-planar. Comparison of Si-C bond lengths with literature data indicates an electron donating effect of the terminal thienyl ring on the first C linked to the Si central atom. The study of C-C bond lengths reveals a much more aromatic character for the four thienyl rings directly linked to the Si atom. The molecular packing arrangement shows that each molecule presents eight intermolecular contacts.
A Step Forward Standardization of Biocompatibility Testing on Tissue Culture Polystyrene
Authors: Feier Andrei Marian , Manu Doina Ramona , Strnad Gabriela , Dobreanu Minodora , Russu Octav Marius , Portan Diana , Bataga Tiberiu
Published: January 2020

Standard procedures regarding osteoblast cells deposition on different subtrates to test the biocompatibility of materials are not available. Aspects related to cells morphology depending on their number on the surface area of the substrate were studied for the first time. Osteoblasts were successfully isolated from residual bone resulted from two different patients after total hip arthroplasty. Different numbers of osteoblasts in populations (3x104 cells/cm2, 6x104 cells/cm2, 1x105 cells/cm2) were deposited on tissue culture polystyrene for 7 and 10 days of incubation. Results suggested that the protocol of osteoblasts deposition should be adjusted to assure a fair distribution of cells on the entire available area of the substrate, possible if a very good dispersion in the medium is achieved prior to deposition. Some other key factors in cells appropriate development, such as substrate nature, topography and incubation time,were detected. The present investigation helps declaring specific standards with respect to the biocompatibility testing of materials using osteoblast populations. Further investigations may lead to the creation of databases and the establishment of standards regarding bicompatibility researches that involve osteoblasts populations.
Highly Self-Organized Materials: Formation Mechanism and Electrochemical Synthesis
Authors: Portan Diana , Strnad Gabriela , Feier Andrei Marian , Russu Octav Marius
Published: January 2020

A class of intensively studied materials with application in areas where complex structures with precise geometry are needed (i.e. electronics), are the self-organized nanomaterials. Polymer, metallic and composite self-organized nanomaterials have been in researchers� attention the last decades. They are not only appealing scientifically, by revealing the intrinsic atomic and molecular interactions that might be difficult to detect otherwise but may also hold the key for the development of novel functional structures and devices. The different mechanisms and forces involved in the self-formation of organized nanostructures are discussed in the present manuscript. Further on, key formation fundamentals involved in the fabrication of self-organized nanostructures are described. Between the known manufacturing methods, the electrochemical synthesis is considered extremely simple and cost effective. On the other hand, it involves a wide range of synthesis parameters (e.g. voltage, electrolyte type, temperature, experiment duration, pH etc.) that may lead to the formation of ingenious structures with complex geometries at different length scales. Finally, some representative scientific investigations are mentioned together with applications of self-organized nanomaterials in different engineering and life areas.
Comparative Evaluation of the Effect of Surface Polishing of a Glaze/composite Sealant and Different Polishing Systems on Surface Roughness of Three Composite Resin Type
Authors: Bolat Maria , Stoleriu Simona , Iovan Gianina , Pancu Galina , Tofan Nicoleta , Sandu Andrei Victor , Andrian Sorin
Published: January 2020

The aim of the study was to evaluate the influence of different techniques of finishing and polishing as well as the use of sealants on the surface condition of some composite resins used in the dental office. 80 specimens of composite materials (Nanoceramic, Nanocomposit and Nanohybrid) were made and divided into 3 groups G1-coated composite with sealant lacquer, G2 - finished in 2 stages, and G3 - finished in 3 stages. Roughness (Ra) was determined with the Taylor Hobson Form Talysurf Profiometer. The data was analyzed using one-way ANOVA followed by a multiple comparison t test. Significant differences were found between the groups in terms roughness (p [ 0.001). The results showed that Seal - and - Shine (PULPDENT) was capable of reducing surface roughness and provided polished surfaces for all materials.
Iono-molecular Separation with Composite Membranes. VII. Nitrophenols pertraction on capilary polypropylene S-EPDM composite membranes
Authors: Nafliu Ion Marius , Ani Hussam Nadum Abdalraheem Al , Grosu (Miron) Alexandra Raluca , Tanczos Szidonia Katalin , Maior Ioana , Nechifor Aurelia Cristina
Published: January 2020

In the present paper the authors study the pertraction of the nitrophenols through the immobilization using chemical reaction in receiving phase, using a laboratory installation conceived by the Group of Membranes, Materials and Membrane Processes within University Politehnica of Bucharest. This installation was developed using liquid synthetically solutions, through composite membranes having a matrix of capillary polypropylene and inclusions of ethylene propylene diene terpolymer sulfonic acid (S-EPDM) or sulfonated ethylene-propylene-diene terpolymer (S-EPDM). The results were follow: The permeation through the compartments of the system with composite S-EPDM membranes is limited, in the aqueous phases, by the solubility of the compound about to be separated, namely the membrane itself, and subsequently by its diffusion from the feed compartment to the collection compartment. The chemical reaction of immobilization, in the receiving phase, can be achieved in several variants (neutralization, esterification, complexation, oxidation, coupling, oxidative degradation); The biggest flows are obtained in compensation of the o-nitrophenol with ferric ions and then, in acetylation of the o-nitrophenol with acetic anhydride. However, we can emphasize that the derivatization of the o-nitrophenol through complexation and acetylation reactions requires its use as such in later processes, unlike the neutralization, for which the nitrophenolate ion easily frees the nitrophenol for future applications;For the neutralization reaction, the removing coefficient grows with decreasing of pKa value of the nitrophenols. For complexation reaction, the most favorable results were obtained for o-nitrophenol - over 66%;The coupling reaction of the o-nitrophenol, in the receiving phase, with the diazonium chloride of the p-nitroaniline and hydrogen peroxide 3% in sulfuric acid 20%, respectively, concludes with the exhaustion of the source phase, after 24 hours of operation.
Aspect Regarding Plastic Deformations in Tibial Plateau Fractures
Authors: Vaduva Marcel Mihai Berceanu , Petrescu Horatiu , Musallam Rami , Boustani Abdoul Fattah , Velimirovici Milan , Velimirovici Dana Emilia , Rada Maria , Radulescu Matilda , Vaduva Delia Mira Berceanu
Published: January 2020

Our purpose was to study tibial plateau fractures considering the rise of their incidence, their potential immediate seriousness or late complications and their complexity. We realized a clinical-statistical study concerning the incidence of tibial plateau fractures taking in account critaeria like age, sex, mechanism of injury, fracture type and correlations between these. The study involves 126 patients, 98 (77.77%) being treated surgically and 28 (22.22%) conservatory between 2008-2016 in the I-st Clinic of Orthopaedics and Traumatology Timisoara. Approximately 2/3 of cases are of Schatzker type I, II and III. Type VI Schatzker occured in 5.78% of all, the mechanism of injury being split almost equal between road accidents and falls from height. Road accidents prevale as a causing circumstance of tibial plateau fractures. 2/3 of the tibial plateau fractures associate with other significant regional lesions. Bone lesions are not rarely underestimated by plain radiographs. Therefore evacuation of haemarthrosis (showing lipohaemarthrosis) and high performance imaging (CT, MRI) are often needed. In comparison to other fracture sites, imperfect reduction of tibial plateau fractures results more frequently in long term sequellae. Being frequently complex, comminuted fractures with associated regional lesions tibial plateau fractures raise the complexity of the medical act from establishing a complete diagnosis to the final therapeutic measures. For a correct and complete preoperatory diagnosis frequently high performance imaging is needed. Tibial plateau fractures significantly affect patients, the healthcare and social-economic system, the healing and rehabilitation.
Ceftriaxone Intercalated Nanostructures Used to Improve Medical Treatment
Authors: Duceac Letitia Doina , Luca Alina Costina , Mitrea Geta , Banu Elena Ariela , Ciuhodaru Madalina Irina , Ciomaga Irina , Ichim Daniela Luminita , Baci Ginel
Published: January 2020

The development of antibiotic resistance in bacteria possesses a huge threat to public health by nullifying the effect of even the most efficient antibiotics. From years, LDHs type nanomaterials have been used as drug carriers for a wide variety of pharmaceutically active molecules due to their delivery properties, making these inorganic-organic nanohybrids very efficient antimicrobial agents. The major purpose of this work was to synthesize and characterize ceftriaxone intercalated layered nanostructures for further use to treat some infections, mostly of them child infections. The novel nanohybrid materials were prepared by ion exchange route and coprecipitation method. Structural and morphological characterization was performed by FTIR, EDX and SEM techniques. The results revealed a high incorporation of the drug in the interlayer space of promising nanostructures.
The Choice of Recycling Methods for Single-Polymer Polyester Composites
Authors: Gawdzinska Katarzyna , Nabialek Marcin , Sandu Andrei Victor , Bryll Katarzyna
Published: January 2020

This work has described the production of single-polymer composites by the film-stacking method. Two types of single-polymer composites with different mass fractions of the polyester reinforcement phase (10% and 20%) and the PETG matrix were investigated. The produced composites were subsequently recycled by injection moulding, pressing, and extrusion. Selected properties of the processed composites were determined: density, viscosity-average molecular weight, impact resistance, and tensile strength. The work done in this paper has demonstrated the benefits and drawbacks of each recycling method for these materials. The selected properties of single-polymer polyester composites and single-polymer polyester composites that were recycled by extrusion have also been compared.
Hemiarthroplasty in Complex Proximal Humeral Fractures Is uncemented methaphyseal corundum blasted titanium humeral stem an efficent alternative?
Authors: Scripcaru Andrei , Berea Grigore , Cotrutz Elena Carmen , Stan Cristinel Ionel , Puha Bogdan
Published: January 2020

The aim of this experimental study is to reveal the design and characteristics of unipolar shoulder prosthesis type Arrow (Groupe FH�, France) as well as to evaluate the outcome of the proximal humerus fracture treated with this implant. 8 patients with a mean age of 62.5 years were operated with immediate passive rehabilitation and active exercises initiated around day 45. All patients had good results with minimal pain, a mean Constant - Murley score of 74 and an acceptable shoulder amplitude. The clinical success was assured by the anatomic union of the tuberosities around the implant. The Arrow metaphyseal corundum blasted humeral titanium stem assures a perfect osseointegration with optimal stability and is an efficient alternative for shoulder hemiarthroplasty.
Aspects Regarding the Braking Capacity of Composite Brake Shoes for Railway Vehicles
Authors: Cruceanu Catalin , Craciun Camil
Published: January 2020

The main target of the study is to highlight, by means of numerical simulations, the advantages and possible drawbacks of using composite materials instead of the classical cast iron to equip the brake system of railway freight vehicles. The qualitative and quantitative evaluations refer mainly to the braking capacity by considering as main parameter the stopping distance, in various operational conditions. Results indicate that composite materials are more efficient in the braking process, but in the case of low speeds, the recommendation is to perform earlier and/or stronger braking actions than usual, in classical cast iron equipment on rolling stock.
Aspects Regarding the Tribological Behavior of Turcite and Relamid Polymeric Materials, in Sliding Motion Couples
Authors: Petre Ivona Camelia , Popescu Ileana Nicoleta , Ungureanu Dan Nicolae
Published: January 2020

The application of plastic materials in various areas of contemporary technology can lead to improvements in the function, quality and performance of engineering components. When determining the field of use of these materials, it is necessary, in addition to knowing the physical and mechanical properties, information about their behavior in service under the influence of the operating and environment factors. Compared to metallic or ceramic materials, polymeric materials exhibit a wide range of scratching deformations in a narrow range of pressure, speed, temperature, lubrication etc.In this paper is proposed a penetration model of a flat surface (from polymeric material) with a rigid conical penetrator and the determination of the flat surface material response mode. The penetration method corresponds to the deformation produced by the asperities in practice.The comparison of the experimental and the theoretical results confirms the veracity of the model and corresponds with many of the experimental results obtained in the specialized works.Based on the proposed models, maps can be produced, that can illustrate the response of any polymeric surface in contact with an abrasive material.
Flexible Acrylate Dentures versus Chromium Cobalt Removable Partial Dentures - a Viable Therapeutical Solution
Authors: Bosinceanu Dana Gabriela , Sandu Ioan Gabriel , Baciu Elena Raluca , Bosinceanu Dan Nicolae , Surlari Zinovia , Martu Ioana , Balcos Carina , Bolat Maria
Published: January 2020

The aim of this study was to compare the evaluation of two groups of denture wearers following specific parameters at 6 and 12 month after the treatment..The study group included 15 patients with Cr-Co alloy skeletal dentures with metallic crowns with distal occlusal clasps and the base of methyl polymethacrylate (PMMA) and 15 with partially flexible dentures made of super-nylon polyamide resin. Based on the evaluation of these dentures, the 7 clinical parameters stated, over a period of 18 months and within the limits of this study, it can be concluded that partial removable dentures made of nylon-Valplast superpolyamide can be considered as a viable option to Cr-Co alloy.
Flocculant Based on Acrylamide and Acrylic Acid Grafted on Sodium Alginate by Electron Beam Irradiation
Authors: Craciun Gabriela , Manaila Elena , Ighigeanu Daniel
Published: January 2020

The paper presents the obtaining, characterization and testing of a new type of polyelectrolyte based on acrylamide (2.63 mol/L), acrylic acid (1.73 mol/L) and sodium alginate (4.63x10-3 and 9.26x10-3 mol/L), for flocculation purposes. Two types of monomeric solutions were irradiated in electron beam at room temperature and in atmospheric conditions with doses between 0.5 and 2 kGy using ALID 7 linear electron accelerator of 5.5 MeV. The potassium persulfate (9.25x10-4 mol/L) was used as reaction initiator in both types of solutions. The flocculants thus obtained were characterized using various physical and chemical methods in order to determine conversion coefficient, residual monomer content, intrinsic viscosity, grafting ratio and grafting efficiency. The flocculation efficiency was evaluated in 0.1 and 0.2 wt % blue kaolin suspension at room temperature using a standard Jar test apparatus.
Comparative Studies on the Electrical and Mechanical Behavior of Some Soldering and / or Impregnation Lacquers
Authors: Bors Adriana-Mariana , Lingvay Daniel , Caramitu Alina-Ruxandra , Iordache Iulian , Lingvay Iosif
Published: January 2020

In order to evaluate the behavior in various electrical applications, the main mechanical and electrical characteristics of three different varieties of specifically chosen lacquers - based on alkyl-epoxy-melamine copolymer, the epoxy polymer and polyurethane were compared. From the mechanical determinations, it was found that at ambient temperature the polyurethane lacquer bending resistance was approximately equal to that of the epoxy lacquer and about 6.5 times higher that of the alkyl-epoxy-melamine copolymer. It has also been shown that at bending force of less than 150 Nm the investigated polyurethane lacquer has relatively large deformations of 0.4 mm / kN, which indicates a high capacity to take over relatively high deformations of the metal support (due to thermal expansion from various applications) without significant increasing mechanical stress. The recorded values for the alkyl-epoxy-melamine-based copolymer lacquer and the pure epoxy lacquer are 0.11 mm / kN and 0.03 mm / kN respectively. Determinations by dielectric spectroscopy have shown that at frequencies below 250 Hz the dielectric losses tgd for the epoxy and polyurethane lacquers are approximately equal and are about 2.9 times lower than for the alkyl-epoxy-melamine copolymer lacquer. It was also found that at frequencies higher than 250 Hz the investigated materials behave differently, respectively at the frequency increase up to 10 kHz, the dielectric loss tgd of the polyurethane lacquer remains constant at about 0.0045 in contrast to the epoxide lacquer at which the dielectric loss tgd increases monotone to 0.0095 at 10 kHz, respectively of the alkyl-epoxy-melamine copolymer at which the dielectric loss tgd is approximately constant 0.012 in the 250 Hz-10 kHz range.
Mechanical and Thermal Properties of Styrene-diene Block Copolymers Films Obtained by Spin Casting from Different Solvents
Authors: Ghioca Paul , Iancu Lorena , Grigorescu Ramona Marina , Ion Rodica-Mariana , Grigore Madalina Elena , Spurcaciu Bogdan , Gabor Raluca Augusta , Nicolae Cristian-Andi
Published: January 2020

This paper presents the solvents effect on the mechanical and thermal properties of films of styrene-butadiene and styrene-isoprene block copolymers with the majority diene phase, obtained by spin casting.
Study on a New Classification of Causes which Generate Deffects of Injection Molding Products
Authors: Luca Liliana , Pasare Minodora Maria
Published: January 2020

In this paper we present a study that was conducted to determine the classification of causes that generate defects in products obtained by injection of plastic material. A classification of the causes of defects is made by applying a quality management tool - the Ishikawa diagram. The causes are grouped into M categories, for defects generated by the design process and for defects generated by the injection process. A new model of the diagram is created by composing two fish skeletons (model 4M + 5M). At the end of the paper, the importance of the Ishikawa diagram is shown.
Evaluation of Stable Balance Capacity by Using Bosu Ball Surfaces on Different Pressure Levels
Authors: Badau Adela , Badau Dana , Enoiu Razvan Sandu
Published: January 2020

The purpose of the study was to evaluate the way in which bimanual and unimanual balanced balance values depend on the technical characteristics of using both Bosu ball surfaces in relation to three pressure levels: 0.6 atm., 0.4 atm. and 0.2 atm. The results have shown that steady manual balance is dependent on the characteristics of the equipment used. The lower the ball�s pressure, the balancebalance becomes worse. Testing the stable hand-balance on the round-up has scored better than the round-side down of Bosu ball.
Biochemistry in Assessing the Inflammatory Response of the Respiratory System Due to Experimental Exposure to Glass Fibres
Authors: Domokos-Hancu Bianca , Man Milena Adina , Trofor Antigona Carmen , Pop Carmen Monica , Gavrilescu Cristina Maria , Cojocaru Elena , Cernomaz Andrei , Lesan Andrei , Boerescu Cristian , Barbu Roxana-Mihaela , Popescu Florina
Published: January 2020

Given the structural resemblances between glass fiber and asbestos, it is important to understand the mechanisms through which exposure to glass fibers may affect the respiratory system. To study the effect of glass fiber on rat lung through intratracheal exposure, considering the subject�s weight variation, together with haematological parameters, C-reactive protein (CRP), total number of lymphocytes, and IL8 concentration in bronchoalveolar lavage. We performed an intratracheal instillation study on four groups of 8 randomly selected Wistar rats, by administering 3 different doses of glass fiber. The hematocrit value was an indirect indicator of chronic hypoxemia; leukocytes and the C-reactive protein assessed systemic inflammation, and total number of lymphocytes and IL8 concentration in bronchoalveolar lavage fluid determined the lung�s inflammatory response. Weight variation evaluated in all 8 measurements revealed no statistically significant changes (p=0.768). The decrease in mean blood leukocytes was interpreted in relation with the glass fiber dose, with a statistically significant difference between the study groups (p=0.003). Statistically significant differences were found in the CRP values, with dose correlations (p[0.001). The bronchoalveolar lavage fluid showed increased levels of IL-8 (p[0.05), and decrease of lymphocytes (p[0.001) in correlation with the administered glass fiber dose. The inflammatory response following exposure to glass fibers in rats is correlated with administrated glass fiber dose. The alterations described as a result of intratracheal glass fiber instillation could predict the effects which occupational exposure to glass fiber may produce in humans.
Experimental and Virtual Studies in Mechanical Applications of PP-RCT Pipes with Armored Materials
Authors: Enescu Maria Cristiana , Stoian Elena Valentina , Negrea Alexis , Mihai Simona , Petre Ivona , Rusanescu Carmen Otilia
Published: January 2020

The new generation of newly developed materials, namely the high-crystallinity and high temperature polypropylene random copolymer, called PP-RCT, increases the crystalline capability of polypropylene, which allows pipes produced from this material to operate at higher pressures at elevated temperatures. Pressure tests on pipes made of PP-RCT materials show a resistance over a period of 50 years at 7000C (1580 F) 5 MPa (725 psi) compared with 3.2 MPa (464 psi) for standard materials PPR. By reinforcing PP-RCT with aluminum, glass and basalt composite results in a more resistant structure. As a result of the traction tests, it was found that in all three samples the tensile strength exceeds the manufacturer s limit (10 - 12.7 MPa), the values obtained being: st1 = 8 MPa - sample no. 1; st2 = 13 MPa - sample no. 2; st1 = 11 MPa - sample no. 3. The fiber glass insert is less resistant, the best variant being the basal insect sample (st2 = 13 MPa). Elongation at break for specimen no. 3 was recorded at 0.027 mm / mm. Tests on these material combinations were performed for stretching and flexing requests and compared to 3D created virtual models. Simulations of internal pressure behavior were also performed for different material configurations and the results were compared with the experimental data and the data supplied by the manufacturers.
Ageing of Some Lacquers Due to Microbiological Stress
Authors: Bors Adriana-Mariana , Lungulescu Marius-Eduard , Nicula (Butoi) Nicoleta Oana , Caramitu Alina-Ruxandra , Lingvay Iosif
Published: January 2020

This paper shows the ageing study of some coatings and / or impregnation lacquers due to microbiological stress through fungal attack. Dielectric spectroscopy has shown that the dielectric losses of the investigated materials increase as result of microbiological ageing. The mean recorded increases are about 4 times for the alkyl-epoxy-melamine copolymer, 2 times for epoxy polymer and 1.5 times for urethane polymer in agreement with the mould coverage degree of about 20 %, 10 %, and 3 %, respectively. The fungal attack of the investigated polymers led to a decrease in volume resistivity of about 65 % for the alkyl-epoxy-melamine copolymer, 45 % for the epoxy polymer, and 14 % for polyurethane, in agreement with the increase of dielectric losses and degree of mold coverage of the samples. FTIR determinations have shown that fungal attack significantly increased the number of aliphatic -OH and C-H bonds and decreased the number of C-O bonds, respectively of C-O-C oxiran groups and C-C aromatic bonds. DSC thermograms recorded at different temperature ranges and the activation energies calculation for first major oxidation process indicate that after the fungal attack the thermooxidative reactivity of the investigated polymers increases.
Tensile Behaviour of Fabric Reinforced Laminates and Plies
Authors: Capatina Ana , Bria Vasile , Bunea Marina , Birsan Iulian-Gabriel
Published: January 2020

The present paper is concerning to an empirical analysis of tensile properties of plies and laminates formed with an epoxy matrix and with various carbon fiber fabrics. The analysis was started with the aim of finding some correlations between the elastic parameters of plies and elastic parameters of laminates when fabrics are used as reinforcements. Six different carbon fiber fabrics were used to analyze the plies and laminates mechanical parameters. The epoxy system Epiphen RE-4020-DE4020 was used in both cases as matrix. The mechanical response to tensile test was analyzed for above mentioned materials and the results had been compared with values obtained by application of various purposed models.
Influences of Polymeric Magnetic Encapsulated Nanoparticles on the Adhesive Layer for Composite Materials Used for Class I Dental Fillings
Authors: Zaharia Cristian , Sinescu Cosmin , Gabor Alin-Gabriel , Socoliuc Vlad , Talpos Serban , Hajaj Tareq , Sfirloaga paula , Oancea Roxana , Miclau Marinela , Negrutiu Meda-Lavinia
Published: January 2020

The main properties of dental adhesives should be good marginal adaptation, high retention strength and the possibility of not negatively influencing clinical sustainability. Dental adhesives are continuously improving to increase their retention to dental structures by increasing penetration in these structures, as it was shownin the in-vitro tests requiring imaging and qualitative analysis to allow the evaluation of experimental samples as well as the development of new materials. The main objective of this study is the qualitative and quantitative analysis of the layer of modified dental adhesives with ferrous nanoparticles encapsulated in a SiO2 membrane located between the surface of the dental preparation and the surface of the photopolymerizable composite filling. For qualitative and quantitative analysis of the samples, technologies such as SEM, optical microscopy and EDX were used.
Experimental and Finite Element Analysis of the Open-Cells Porous Materials Subjected to Compression Mechanical Loading
Authors: Chicos Lucia-Antoneta , Campbell Ian , Zaharia Sebastian Marian , Pop Mihai Alin , Lancea Camil , Semenescu Augustin , Florea Bogdan , Chivu Oana Roxana
Published: January 2020

Progress in Additive Manufacturing (AM) technology enables the fabrication of complex structures that could not be obtained with traditional manufacturing methods. One AM research area is the development and use of lightweight products with cellular structures, containing complex lattices and pores, which give improved performance and functionality. It is well known that there is a strong link between mechanical properties and architecture of samples with cellular structures. This paper presents a comparison and validation of Finite Element Analysis (FEA) simulations of cellular structures with experimental data obtained from compression tests, and degradation behaviour under load compression. The specimens, with spherical open-cells, were produced in VeroClear RGD810 photopolymer resin. Mechanical compression tests were performed to investigate the compressive behaviour and the mechanical response was registered in the form of compressive stress-strain curves. Also, using the specimens� CAD data and compression test parameters, a Finite Element Analysis (FEA) was performed. A macroscopic analysis of the specimens� structure and microhardness tests before and after compression tests were also carried out.
Calculation of the Cross Section Active Area for a Polymeric Spiral Wound Reverse Osmosis Membrane
Authors: Dascalu Mihaela-Elena , Nedeff Florin , Ciubotariu Vlad , Lopez-Ramirez Juan Antonio , Sandu Ion
Published: January 2020

Cross flow filtration is the typical way that water is filtered in membrane technology; that means that feed solution passes tangencially over the membrane and rejected components are washed away of the membrane by the rejected stream. In such a way, that minimal solids building up and at constant low flow resistance are achieved. In this paper, a calulation method regarding to the value of cross-section active area for a polymeric spiral wound reverse osmosis (RO) membrane is presented, in order to obtain the value of the cross-flow velocity of the system. This velocity is needed to improve the knowledge fouling mechanisms and it is not easy to know without obtaining the cross section area. To determine cross-section area of a RO polymeric spiral wound membrane a series of calculations were performed to obtain the initial values of some parameters. The mathematical calculation was also achieved with the Roll Length program. Based on the results obtained, it was concluded that only 65.36% of the total cross-section of the membrane is useful to cross flow and it was possible to determine the active cross-section of filtration with a value of 1,915.4 mm2, for the membrane studied. This methodology allows the calculation for any RO spiral membrane.
Touch Screen Tester Device End-Effector
Authors: Timpea Stefan Adrian , Cosma Cristian , Sosdean Danut
Published: January 2020

The paper describes the implementation of a new type of End-effector for testing touch screen devices. To automate the testing process of touch screens devices, a new type of end-effector is presented. The End-effector can be attached at diferent tipes of robotics sistem trough a connection part, which can be designed depending on the type of robot. For the movements in the test scenario, the end-effector is designed to move like a human hand. To create the physical parts in the prototype phase is used an field of rapid prototyping (RP) technology, called fused deposition modeling (FDM).
Studies on a Levonorgestrel-Releasing Trade Plastic Device and on a Similar Polyurethane Foam Used as a Levonorgestrel Carrier
Authors: Olaru Flavius , Stoian Dana , Vaduva Delia Berceanu , Corpade Alina , Birsasteanu Florin , Navolan Dan , Luca Constantin Tudor , Cretu Octavian , Carabineanu Adrian , Motoi Sorin , Borcan Florin , Craina Marius , Dobrescu Amadeus
Published: January 2020

Hormonal Intrauterine Devices (IUD) were developed based on copper IUD with the role to release a daily amount of hormones. From a structural point of view Levonorgestrel-IUD (L-IUD) is a small T-shaped piece of plastic, which contains levonorgestrel. When compared with the oral route of L-IUD administration, it provides some advantages because it releases levonorgestrel directly into the uterus. Our aims were: (1) to compare the thickness of uterine jonctional zone (UJZ) in two groups of patients with and without inserted L-IUD, (2) to evaluate the changes in thickness of UJZ after the insertion of L-IUD in two patients with adenomyosis, and (3) to obtain and to characterize a similar T-shaped polyurethane (PU) foam used as a levonorgestrel delivery system. On the one hand, the results confirm that L-IUD is effective in thinning the UJZ and in the treatment of adenomyosis, while on the other hand, the characterization of the PU materials (Zetasizer measurements, their thermal degradation, UV-Vis spectra and skin irritation tests) revealed that this polymer can be used as a safety and prolonged levonorgestrel carrier.
Functionalization of Mesoporous Silica Materials Using Calix[4]arenes
Authors: Olteanu Marius , Septelean Raluca , Nemes Ovidiu , Grec Delia , Gal Emese , Porumb Dan , Deak Gyorgy , Baraitaru Andreea
Published: January 2020

\Six new products were obtained by deposition of para-tert-butylcalix[4]arene (t-Bu-C4OH), calix[4]arene (C4OH) and tetra-methoxy-calix[4]arene (C4OMe) on two types of SBA-15 mesoporous silica. All the products were characterized through thermogravimetric methods and SEM microscopy. The obtained results confirm the functionalization of the silica materials with the calixarene macrocycles. Considering all the obtained products, the thermal analysis suggests the strongest connectivity to form between the C4OMe systems and mesoporous silica substrate.
Structure and Selected Properties of Intraocular Implants (PMMA, Acrylic)
Authors: Gacek Marcin , Wyslocki Jerzy , Gondro Joanna , Badura Franciszek , Letkiewicz Slawomir
Published: January 2020

This paper presents the results of an investigation into the structure and properties of intraocular lenses (IOL) that are available on the ophthalmological market. The majority of implants of this type are based on acrylics or poly(methyl methacrylate) (PMMA). The acrylic lenses can be curled, which allows the making of just a minor incision during the associated implant surgery. The drawback of PMMA implants is their high rigidity, resulting in the need for a larger incision during the implant surgery. The benefits accrued from wearing such an implant are (1) the correction of focus for clear vision and (2) protection of the retina against UV-A radiation. X-ray diffractometry has confirmed the amorphous structure of all of the lenses investigated in this paper. The absorption and transmittance of the selected implants have been measured; differences found in the directional values of the transmittance and absorbance suggest the presence of differences in the implant coating (such as: different thickness or lack of coating on one side). It has been found that the PMMA-based implants exhibit the better properties with a level of light transmission in the visible spectrum of almost 40% and total protection against UV radiation. The acrylic implants feature lower transmittance in the visible light spectrum, and two of the investigated acrylic lenses failed to provide adequate protection against the UV radiation.
A Study of two Dimensional Metal Carbide MXene Ti3C2 Synthesis, characterization conductivity and radiation properties
Authors: Rasid Zarrul Azwan Mohd , Omar Mohd Firdaus , Nazeri Muhammad Firdaus Mohd , Saidi Syahrul Affandi , Sandu Andrei Victor , Mohd Mustafa Al Bakri Abdullah
Published: January 2020

Since the discovery of exceptional properties of graphene, a lot of researchers focused on the discovery of another nobel two-dimensional (2D) materials. Recently, an elegant exfoliation approaches was proposed as a method to synthesis a new family of transitional 2D metal carbide or nitrades of MXene from a layered MAX phase. A layered MAX phase of Ti3AlC2 was synthesized through pressureless sintering (PLS) the initial powder of 3TiH2/1.1Al/2C without preliminary dehydrogenation under argon atmosphere at 1350 oC. An elegant exfoliation approach was used to eliminates Al from its precursor to form a layered-structure of Ti3C2. In this study, thermal conductivity of MAX phase and MXene were studied using absolute axial heat flow method to measure the abilities sample to conduct heat and the data was collected using Picolog 1216 Data Logger. Electrical conductivity of these two materials was also compared by using two-point probe, due to its simplicity. Radiation properties of 2D MXene Ti3C2 was studied by using an established radon monitor, placed in closed, fabricated container. Morphological and structural properties of this 2D material were also studied using an established FESEM and XRD apparatus. SEM images shows two types of morphology which is a layer of Ti3C2 and the agglomerates Al2O3 with graphite. XRD pattern reveals three phases in this material which is a rhombohedral Al2O3, rhombohedral graphite and rhombohedral Ti3C2 phases, respectively. Thermal and electrical conductivity of MXene were proven higher than MAX phase. Radon concentration for this material for five consecutive days explains the radiation level of this material which is under the suggestion value from US Environmental Protection Agency (EPA). From this finding, it is can conveniently say that the MXene material can be promising material for electronic application.