bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of 3D Planning, Plastic Materials and Additive Manufacturing in Functional Rehabilitations in the Head and Neck Surgery
Authors: Muhlfay Gheorghe , Fabian Zoltan , Neagoe Radu , Horvath Karin Ursula
Published: January 2020

The developments in the biocompatible materials and additive manufacturing technologies gave birth to new possibilities in reconstructive surgery. In addition to revolutionizing the diagnostic possibilities, the modern medical imaging has led to the development of surgical planning software. Using these state-of-the-art technologies, a new standard of care is rising with the spread of patient specific implants. Our view in studying and using these materials and technologies goes beyond their biocompatibility, focusing on the functional and esthetic impact of these restorations. Our aim is to show their potential benefits and pitfalls presenting a couple of posttraumatic and oncological application possibilities, focusing on the new presurgical planning, choice of materials and manufacturing technologies.
Morphological and Dynamic Mechanical Analysis of Vibration Damping Composite Material Based on Different Elastomers
Authors: Yurkin Yu. V. , Mansurova I. A. , Belozerov V. S. , Zlobina A.
Published: January 2020

This work deals with the problem of developing vibration damping polymeric materials which are effective at low temperatures (from minus 40 to 0�C). Due to the fact that the vibration damping efficiency in the composite is mainly determined by the properties of the polymer matrix, it is necessary to study its properties depending on the type and amount of structure-forming parameters. The purpose of the work is to determine the changes in the dynamic properties of the polymer composition based on butyl rubber, EPDM, ethylene-vinyl acetate copolymer (EVA) filled with increasing amount of calcium carbonate. The leading methods of studying this problem were the method of scanning electron microscopy and the method of dynamic mechanical analysis. It has been stated that the selected polymers can be considered as competent candidates for damping materials at low temperatures, and the calcium carbonate filler allows more fully to realize the vibration damping properties of the polymer. The obtained dependences can be used as initial data for analytical predicting of damping properties of polymer composites.
Effect of Temperature and Moisture on the Tensile Properties of a TEPs-Modified Adhesive
Authors: Banea Mariana D. , Silva Lucas F.m. Da , Carbas Ricardo , Barros Silvio De
Published: January 2020

The main factors that affect the strength of adhesive joints are the exposure to moist environments and high and/or low temperatures. The objective of this paper is to measure the water diffusion in adhesives modified with thermally expandable particles (TEPs) and assess the joint strength of water saturated modified adhesives. Bulk specimens were used to measure the diffusion coefficient of water in a TEPs-modified adhesive. The tensile data as a function of TEPs content, moisture uptake and temperature was measured. It was found that the presence of moisture and the temperature affect the mechanical properties of TEPs-modified adhesive. Further, a scanning electron microscope (SEM) analysis was performed in order to examine the fracture surfaces of the tensile specimens tested as a function of temperature and water uptake. SEM analysis showed that the absorbed moisture and temperature change the fracture mechanisms and the morphology of the specimens.
3D-Printed, Non-assembly, Pneumatically Actuated Mechanisms from Thermoplastic Materials
Authors: Zapciu Aurelian , Amza Catalin Gheorghe , Rontescu Corneliu , Tasca Gabriel
Published: January 2020

Various applications in industry and medicine require the transmission of movement using systems that do not influence magnetic or electromagnetic fields. These components include systems which transmit linear or rotational motion, change position (switches), attach or detach to objects (latches), grip objects, etc. This paper looks into the possibility of producing such mechanisms using FDM 3D-printed parts from thermoplastic materials with embedded moving parts, which can be pneumatically actuated. In order to make the parts suitable for use in pressurized air systems, different sets of printing parameters have been investigated. PLA annealing is used in the attempt to minimize play and increase air-tightness of 3D-printed parts.
Testing Methods of Assessment for the Chemical Resistance of Insulating Materials Against the Effect of Selected Acids
Authors: Otrisal Pavel , Melicharik Zdenek , Svorc Lubomir , Bungau Simona , Virca Ioan , Barsan Ghita , Mosteanu Danut
Published: January 2020

The Czech Armed Forces' soldiers of all specializations and mainly the chemical corps'specialist are prepared for task fulfillment in military and non-military operations within those a real threat of weapons of mass destruction employment and, occasionally, the real danger of toxic industrial materials leakage is present. They can solve problems caused by acids leakage in contaminated areas mainly during task fulfillment in non-military operations on the Czech Republic territory in cooperation with Fire Rescue Brigades' chemical specialists. Individual protective equipment which is established in the Czech Armed Forces were neither design for this purpose and, moreover, nor tested and thus there is no real data concerning their chemical resistivity. In recent time, some methods have been introduced into the Czech Armed Forces environment. They are useful for determination of chemical resistivity of barrier materials against toxic compounds detectable with acid-basic (colorimetric) methods and conductometric ones. The paper deals with the possibility of using the presented methods and compares the suitability of their application in relation to the protective garments designated for the Czech Armed Forces members' body surface.
Development and 3D Printing of an ABS Ergonomic Handle for Medical Use A case study
Authors: Vlasceanu Daniel , Baciu Florin , Popescu Diana , Hadar Anton , Marinescu Rodica
Published: January 2020

This paper presents a study undertaken following the collaboration between specialists in two multidisciplinary fields, namely engineering and medicine. It was aimed at solving a practical problem by developing of a handle for use in orthopedic surgery. Specific engineering tools, knowledge and processes and methods were used for accomplishing this task. Tailoring devices according to surgeons preferences for ensuring an ergonomic use is an important criterion alongside functional and sterilization requirements, cost and fabrication time, 3D printing representing a feasible manufacturing solution as this research proves. The article details the steps required to complete the final product: design and redesign, numerical analysis, prototypes manufacturing and testing. To perform the numerical analysis that highlights the device mechanical behavior, finite element method was used in assessing different handle designs.
Study on the Need for Postoperative Analgesic Medication in Patients where Polypropylene Mesh was Used in the Surgical Treatment of Incisional Hernias
Authors: Halmaciu Ioana , Suciu Bogdan Andrei , Trambitas Cristian , Vunvulea Vlad , Stoica Alexandra Martin , Godja Dumitru , Fodor Decebal , Brinzaniuc Klara , Molnar Calin
Published: January 2020

One of the most common postoperative complications that may occur in patients treated for incisional hernias is pain. The occurrence of postoperative pain refractory to drug treatment may worsen the prognosis of these patients. We have carried out a retrospective observational study in which we have introduced 122 patients operated for incisional hernia at the Surgical Clinic No. 1 in the Tirgu Mures Emergency County Clinical Hospital. The patients included in the study were divided into two groups: group A consisting of 80 patients where the polypropylene mesh was used over the aponeurosis in the surgical treatment of the incisional hernias, and the group B consisting of 42 patients where no prosthetic materials were used in the surgical treatment of the incisional hernias. All patients were administrated 1 g of sodium metamizole monohydrate for the treatment of pain. The statistical analysis of the data revealed that, on the day of surgery, on the first, second and third postoperative day there were statistically significant differences in the need for analgesic medication between the two groups, the need for the analgesic medication being lower for group A. In contrast, on the 4th postoperative day there were no statistically significant differences in the need for analgesic medication between the two groups. In conclusion, our study showed that, when using the polypropylene mesh in the surgical treatment of incisional hernias, the need for analgesic medication is lower in the immediate postoperative period compared to cases where surgical meshes are not used in the surgical treatment of these patients.
Studies of Humic Acid Removal from Aqueous Systems by Using Polymeric Membrane Ultrafiltration Process
Authors: Tataru Laureniu , Nedeff Valentin , Barsan Narcis , Mosnegutu Emilian , Lehadus Mirela Panainte , Sandu Ion , Chitimus Dana
Published: January 2020

This paper proposes to investigate in detail the behavior of polymeric membranes ultrafiltration process uses in the retention of humic acid from aqueous systems. Nowadays, the aqueous systems (contaminated water and/or wastewater) resulting from various domestic and industrial activities contain many contaminants, some of them increasingly dangerous to the environment. Laboratory testing of membranes in the ultrafiltration process as well as their experimentation with different chemical compounds is essential because it is important to know how they can be eliminated before they cause a negative impact. Testing of polymeric membranes consists in carrying out the process of ultrafiltration of aqueous systems containing humic acid over a set time, following the variation in time of the volume of permeate obtained as well as the influence of process parameters. Following the investigation of the ultrafiltration process of the water through the polymeric membrane, it was found that the formation of the humic acid layer on the surface of the membrane that favors fouling is delayed, after many hours of operation, due to both the internal fiber structure which offers advantages to this type of membranes as well as high efficiency of humic acid retention. Experimental results showed that the humic acid retention rate increased by up to 37% as a result of the double decrease of the conductivity value in the permeate samples from about 600 mS/cm to 373 mS/cm and the temperature being continuously increasing, from 22.5 at 25oC over 5 h influenced the entire ultrafiltration process. The full process approach as well as the expression and interpretation of the results will be detailed in this paper.
Clinical Use of a New Polymer in Complete Dentures Fabrication. II
Authors: Bosinceanu Dana Gabriela , Sandu Ioan Gabriel , Baciu Elena Raluca , Surlari Zinovia , Bolat Maria , Forna Norina Consuela
Published: January 2020

In total edentulous treatment can be used a variety of means capable to reconstruct through artificial prosthetic devices the edentulous dental arches, in an individualized manner depending on the clinical situation, objectives and criteria for treatment. The present study was intended to evaluate the effectiveness of general treatment with vitamin B12 and the effectiveness of local treatment, achieved through complete dentures and to emphasize the much easier and cheaper way to do the same treatment over the same time period.
Comparative Study on Plastic Materials as a New Source of Energy
Authors: Constantinescu Marius , Bucura Felicia , Ionete Roxana-Elena , Niculescu Violeta-Carolina , Ionete Eusebiu Ilarian , Zaharioiu Anca , Oancea Simona , Miricioiu Marius Gheorghe
Published: January 2020

The pyrolysis can be an attractive way to reduce the plastic waste and, in the same time, to obtain alternative conventional fuels. In this respect, four polymers (low-density polyethylene, high-density polyethylene, propylene and polystyrene) were used in the pyrolysis process. The experiments were carried out by using an in-house plant, which allowed a maximum test temperature of 450 �C. The product oil and the derived gas from the pyrolysis process were evaluated using different techniques, such as elemental analysis (EA), calorimetry, gas chromatography (GC), gas chromatography coupled with mass spectrometry (GC-MS). Furthermore, for a comparative study two catalysts, zeolite and lignite, were also used for the pyrolysis process, in order to observe their influences on the final products. The higher heating value obtained for the oil was in the 40.17-45.35 MJ/kg range, acceptable for the use of these oil as an alternative fuel for diesel engine. Also, the sulphur content from the obtained oil does not cause environment problems, being lower than the allowed limits (10 mg/L). In addition, the pyrolysis derived gas was rich in hydrocarbons, conducting to a high calorific value, in the 73.42 - 121.18 MJ/kg range.
New Trend for Using the Reduced Graphene Oxide as Effective and Eco-friendly Nematicide
Authors: Gareeb Rehab Yassin , Elnouby Mohamed Salah , Hasan Moauyed Aziz , Ticu (Cotorcea) Simona , Popa Amorin , Bungau Simona , Hafez Elsayed Elsayed
Published: January 2020

Reduced graphene oxide (r-GO) was synthesized chemically and it was characterized using Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD). The results revealed that the product r-GO is nano-sheets with non-smooth surface; the size of the obtained nano-sheets ranged from 20 to 100 nm. The well characterized nano-sheets were subjected to cytotoxicity test; results demonstrated that the nano-sheets show low cytotoxicity on the human cell line compared with the chemical nematicide. The r-GO was tested against the nematode during their life span and it was observed that the r-GO is capable to reduce the nematode gall number and egg mass of 94% and 99%, respectively. Moreover, the toxicity of the r-GO against the Juvenile (J2) root-knot nematode (Meloidogyne incognita) was also examined either in laboratory or under the greenhouse conditions. On the other hand, the treatment with the r-GO under greenhouse conditions showed higher mortality of the J2 of 98.5% compared with nematicidal treatment of 96% in a soil infested with M. incognita. Also, the same treatment was sufficient in inducting the growth of tomato plants: fresh weight of the shoot system increased with 30% and of the root system increased up to 285%; dry weight of the shoot system increased with 128% and of the root system increased up to 480%. r-GO has a high nematicidal activity and it is safe for human. The r-Go could be used as safe nematocide because it is safe, cheep, could be produced at large scale, and it is a good additive for the soil.
Photocatalytic Degradation of Some Polyolefin-TiO2 Composites Evaluated by Molecular Spectroscopy
Authors: Raditoiu Valentin , Raditoiu Alina , Raduly Monica Florentina , Wagner Luminita Eugenia
Published: January 2020

The photochemical degradation of polyolefin-TiO2 composite films was investigated and described in relationship with the concentration of photocatalyst and after different exposure times. UV-Vis-NIR and IR spectra reveal the presence of various degradation products, which are in direct connection with the photodecomposition mechanism. Various ratios between the absorbance of some typical IR characteristic bands can lead to the evaluation of photocomposition of polyethylene and polypropylene composite films containing TiO2 nanoparticles.The results show that the photocatalytic degradation of composites is significantly faster than the simple photolytic decomposition of pure polypropylene and polyethylene and could be used as a solution for the destruction of this type of wastes.
Applications of Polymeric Membranes Ultrafiltration Process on the Retention of Bentonite Suspension
Authors: Tataru Laurentiu , Nedeff Valentin , Barsan Narcis , Sandu Andrei Victor , Mosnegutu Emilian , Panainte-Lehadus Mirela , Sandu Ion
Published: January 2020

In the field of purification and treatment of waste water resulting from various domestic and industrial activities, classical methods of retention of pollutants almost can no longer eliminate their large quantities, and this signifies a problem related to the environment. Filtration membrane technology has a larger footprint in the removal of these pollutants, and their success is due to virtually the quality of the resulting water. This paper highlights the development of a wastewater ultrafiltration process, containing bentonite, an inorganic compound found in wastewater from industries such as the steel industry, food industry, and so on. This study aims to find the relation between all parameters present in the ultrafiltration process, respectively how these parameters can influence each other. The study is necessary because bentonite, from a common substance, can be a dangerous pollutant, especially if it comes into contact with other compounds that in chemical reactions can harm the environment, and this raises questions to researchers who are experimenting with water purification technologies at a state-of-the-art level. At the same time, the study aims at determining the percentage of bentonite retaining on the membrane filtration surface, and in the final analysis of how bentonite can block the pores of the membrane or deposit on its surface. Throughout the entire ultrafiltration experiment it will be monitorized parameters related to organic membrane with hollow fibers and the results of physico-chemical indicators obtained at the final of the process. The results of the study showed that bentonite can be retained more than 20%. Accumulation of bentonite on the surface of the membrane decreased slightly the volume of permeate at the end of the experiment, resulting in an insignificant decrease in the volume of the liquid in the membrane. The results on bentonite retention efficiency and dependence parameters in the ultrafiltration process will be detailed in the present paper.
Rheological and Microbiological Study on Bio-Composites with Marine Chitosan Polymers from Black Sea Stone Crabs used in Medical Therapy of Tissue Regeneration
Authors: Sirbu Rodica , Mustafa Alef , Tomescu Aneta , Stanciu Gabriela , Cadar Emin
Published: January 2020

In the last years, health care professionals faced with an increasing number of patients suffering from wounds, burns and bedsores difficult to treat and heal. During the wound healing process, the dressing protects the injured area and contributes to the recovery of dermal and epidermal tissues. Because their biocompatibility, biodegradability and similarity to macromolecules recognized by the human body, some natural polymers such as polysaccharides (alginates, chitin, chitosan), proteoglycans and proteins (collagen, gelatin, fibrin) are extensively are used in wounds and burns management. The study presents a research of new semi-solid formulations of bio-composites based on chitosan extracted from the stone crab Pachygrapsus Mormoratus found on the Black Sea shores. The bio-composites were obtained from natural polymeric compounds, Chitosan (CT), hyaluronic acid (HA) and lanolin(L), to which silver sulfadiazine (S), was added. Several semi-solid formulations have been performed for which the antimicrobial activity on gram-positive and gram-negative germ cultures and the rheological behavior was studied. The bio-composites that were obtained provide an optimal micro-environment for cell proliferation, migration and differentiation, due to their biocompatibility, biodegradability, peculiar structure and good antimicrobial activity.
Experimental Researches Regarding the Manufacturing of New Thermoplastic Materials Used in Additive Technologies
Authors: Besnea Daniel , Dinu Elena , Moraru Edgar , Spanu Alina , Rizescu Ciprian , Constantin Victor
Published: January 2020

The article presents the process of manufacturing by adding solid state material (thermoplastic extrusion) in order to achieve new composite deposition materials and to provide new models, raw materials and functional prototypes with superior mechanical features and characteristics. The authors describe the extrusion device as well as the parts manufactured of thermoplastic material.
Study on the Treatment of Postoperative Pain in Patients Operated for Incisional Hernia by Open or Laparoscopic Approach
Authors: Suciu Bogdan Andrei , Trambitas Cristian , Vunvulea Vlad , Godja Dumitru , Kaller Reka , Fodor Decebal , Brinzaniuc Klara , Molnar Calin , Halmaciu Ioana
Published: January 2020

Postoperative pain is a common symptom in the postoperative period in patients treated for incisional hernia, often refractory to treatment. The purpose of the this paper was to conduct a comparative study on the need for analgesic medication in patients operated for incisional hernia through a classical open approach and a laparoscopic approach. In this respect, we performed a retrospective observational study over a period of 4 years in which we introduced 92 patients operated for incisional hernia in the Surgery Clinic No. 1 of the Emergency County Hospital Tirgu Mures. For the reconstruction of the abdominal wall we used prosthetic materials (surgical meshes). All patients included in the study received only metamizole sodium as analgesic medication. The patients studied were divided into two groups: group A (consisting of 57 patients where open, classic surgical approach was used) and group B (consisting of 35 patients treated using a minimally invasive laparoscopic approach). It was observed that on the day of surgery and during the first two postoperative days there are no statistically significant differences in the need for analgesic medication between the studied groups. Instead, starting with the third postoperative day, the need for analgesic medication is much lower in patients where laparoscopic surgical procedure was used than in those where open, classic surgical approach was used.
Use of Biopolymers in Designing Edible Packaging Materials for Food Industry Development of statistical models
Authors: Puscaselu (Gheorghita) Roxana , Severin Traian Lucian , Amariei Sonia
Published: January 2020

This study aims to develop biodegradable and edible materials based on hydrocolloids and to analyze their physical and mechanical properties for use as food packaging. Edible packings were obtained from a hydrocolloid matrix (agar, starch, sodium alginate), plasticized with glycerol in different proportions (33.33% and 16.7% from the total amount of polysaccharides used). The physical and mechanical properties were analyzed. The best results were obtained with agar- sodium alginate packing, plasticized with the highest amount of glycerol.
In Vitro Study of the Structure and Adhesive Interface in Direct Restorations with Commercial Nanocomposite Materials
Authors: Almasi Adrian , Todor Liana , Ratiu Cristian Adrian , Popovici Ramona Amina , Tigmeanu Codruta Victoria , Tofan Sergiu Alexandru , Porumb Anca
Published: January 2020

The purpose of this study was: Structural characterization of two commercial nanocomposite materials (Premise /Kerr Corp and Tetric EvoCeram�/ Ivoclar-Vivadent); Evaluation of the marginal adaptation and adhesive interface achieved with two commercial adhesive systems (Optibond SoloPlus /Kerr Corp and G-Bond /GC). Investigation was done using electronic scanning microscopy (SEM).
Preliminary in vitro Evaluation of a Semisynthetic Oestrogen Polymer-based Formulation
Authors: Utescu Crinela , Berceanu-Vaduva Delia , Luca Constantin Tudor , Farcas Claudia , Dumitrascu Victor , Radulescu Matilda
Published: January 2020

Oestrogen hormones play key roles in the human body, are involved in complex mechanisms, both beneficial and unwanted. Because semisynthetic oestrogens are commonly used today in various hormonal therapies, they has inevitably been linked to the appearance of certain carcinogenic processes, which are primarily based on oestrogen-based drugs, either as initiators or promoters. A promising alternative that can help reduce unwanted effects is to capture the active substance in a polymeric matrix that is capable of retaining its biological activity. In this study, activity on the viability of breast cancer cells with expressed oestrogen receptors of a polymeric formulation with ethinylestradiol and polylactic acid was evaluated.
Comparative Study on the Efficiency of Intermaxillary Elastic Polymers used in the Treatment of Skeletal Class II Malocclusions in Growing Patients
Authors: Vaida Luminita Ligia , Dima Raluca , Cuc Emilia Albinita , Negrutiu Bianca Maria , Moca Abel Emanuel , Lile Ioana Elena , Daragiu Delia , Zalana Alexandru , Albert Elena Luminita , Todor Bianca Ioana
Published: January 2020

The aim of this study was to evaluate the efficiency in using intermaxillary elastics to stimulate mandibular growth and advancement in orthodontic patients diagnosed with skeletal Class II malocclusion as well as to compare the use of these Class II elastics in two different therapeutic approaches. The sample consisted of 60 orthodontic patients aged 10-15 years, 34 girls and 26 boys. The sample was divided into two equal groups (each consisting of 30 patients). Patients belonging to the first group (Group 1) were subjected to 1/4�� - 6.0 oz elastics and were advised to change the elastic every 24 hours. Patients belonging to the second group (Group 2) were subjected to 1/4�- 4.5 oz elastics but with a recommendation to change the elastics every 12 hours. In order to evaluate the effectiveness of these two types of Class II elastics on mandibular growth and advancement, the value of the SNB angle at the beginning of the treatment (T1) was compared with the value of the SNB angle after 5 months of wearing intermaxillary elastics (T2). All patients showed statistically significant increased values of the SNB angle during the orthodontic treatment (p[0.001). Patients in Group 2 showed a significantly higher statistical increase (p[0.05) than patients in Group 1.
Primary Packaging and Stability Evaluation of a Serum Used for the Periorbital Area of the Sensitive Eye
Authors: Muntean Andrei Catalin , Juncan Anca Maria , Moisa Dana Georgiana , Vonica Andreea Loredana , Rus Luca Liviu , Morgovan Claudiu , Gligor Felicia Gabriela , Butuca Anca , Stanila Adriana
Published: January 2020

The aim of this study was the development and formulating of an eye contour serum containing hyaluronic acid (HA) and the assessment of stability tests performed for the cosmetic product, transfered into a glass cosmetic bottle with polipropylene (PP) pump and cap. Sample of cosmetic serum were stored using 20 mL glass bottles with PP (Polypropylene) pump and cap. The developed cosmetic formulation was monitored under accelerated stability studies, 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.
Experimental Study on the Improvement of the Use of Diacrylic Composite Resins in Restorative Dentistry by Compensatory Techiniques
Authors: Vasilescu Elisabeta , Docan Alina , Vasilescu Vlad Gabriel , Popa camelia Lacramioara , Ionel Dan Cristian , Muntenita Cristian
Published: January 2020

The materials as well as the procedures successfully used in modern restorative dentistry are based on scientific selection criteria which can predict outstanding results both in terms of physiological aspects and durability of the workmanship. The rationale of using certain materials and the success or failure to use certain techniques have contributed in time to the evolution of restorative dentistry. The optimal way of combining the material with its application and finishing technique implies an exhaustive approach to the subject that still requires the specialists� research and concern for their improvement and development. Among the restorative materials, those that meet the patients� aesthetic exigencies are the composite resins. In spite of all the advantages resulting from their intrinsic characteristics, it should be noted though that composite resins still have inconveniences related in the first place to the polymerization contraction/shrinkage, which causes a gap between the obturation and the dental tissue further resulting in the generation of marginal micro-infiltrations with all the related drawbacks. Knowing the behavior of the material and understanding its use in various manners can help the practitioner in its efforts to minimize undesirable effects, which is generally possible by applying compensatory clinical techniques. The aim of the experimental research is to evaluate the marginal micro-infiltrations from the class II cavity restorations with composite diacrylic resins according to the different techniques of restoration (stratification technique, flow technique and pre-photopolymerized insert technique) and the establishment of the optimal restorative technique to minimize side effects.
Synthesis and Physico-chemical Characterization of Nanohybrid Materials Based on Isonicotinic Acid Hydrazide
Authors: Banu Elena Ariela , Duceac Letitia Doina , Mitrea Geta , Ciuhodaru Madalina Irina , Ichim Daniela Luminita , Ciomaga Irina Mihaela , Goroftei Roxana Elena Bogdan , Constantin Marcu , Baciu Ginel
Published: January 2020

The usual treatment for tuberculosis is difficult by its long-term therapy, raised dosing frequency and adverse effects of anti-tuberculosis drugs. Anionic clays, also called layered double hydroxides are a class of hydrotalcite like structures having high compositional variety and being able to self-assembly in the presence of drug molecules. The work refers to the development of nanohybrid materials like delivery systems that intercalates isonicotinic acid hydrazide, known as isoniazid anti-tuberculosis drug, into layered structure of hydrotalcite compounds. Loaded drug molecules of isoniazid were proved to be released in a controlled way from the as synthesized nanostructure in a simulated buffer solution. The obtained sample was characterized by advanced techniques thus demonstrating the inclusion of isoniazid antibiotic between hydrotalcite sheets. These results revealed important expectations for further researches of these organic-inorganic nanocomposites for tuberculosis treatment.
Behavior to Dynamic Loads of Multi-layer Composite Structures
Authors: Geanta Victor , Voiculescu Ionelia , Chereches Tudor , Zecheru Teodora , Matache Liviu , Rotariu Adrian
Published: January 2020

The explosive effect and high velocity penetration of the ballistic projectiles of various sizes, design and compositions, on impact with different targets (armors composed of a combination of different metals) are complex. Both practical experiments and mathematical modeling of the phenomena associated to the interaction projectile-target are required to estimate their effect or to design more efficient projectiles and armor. In this study, the basic element of the simulation model is an incendiary projectile of caliber 7.62 mm with medium piercing power, launched with a maximum speed of 750 ms-1 on the multi-material target, which contains 4 different layers assembled into a ballistic cassette made of aluminum. The purpose of this ballistic cassette is to ensure a better contact and handling of multi-layer materials. The proposed model was calculated using mathematical modeling and empirical material constants to describe the nonlinear transitory impact process. Mathematical simulation of the impact between the projectile and target during impact shows that the projectile moves sequentially through the ballistic package, causing perforation, plastic deformation and heating, the resulting fragments being then expelled into the space around the target. The model indicates that the projectile will penetrate the front aluminum plate, as well as the AlCrFeCoNi and steel plates, but will be stopped by the aluminum backing plate. The real impact tests carried out using the ballistic cassette at dynamic impact with the 7.62mm incendiary projectile confirm the model assumptions, which prove the capacity of the composite model to safely stop the projectile.
Mechanical and Morphostructural Characteristics of Composite Materials Performed by Recycling Mixed Waste of Plastic and Paper
Authors: Ciobanu Romeo Cristian , Batrinescu Gheorghe , Ursan George Andrei , Caramitu Alina Ruxandra , Marinescu Virgil , Bors Adriana Mariana , Lingvay Iosif
Published: January 2020

In order to evaluate the possibility of reuse of some mixed waste from plastic and paper, composite samples of both HDPE and PP basis were made with different filler contents of crushed postage envelope waste. From the morphostructural characterization (SEM images) of the samples obtained it was observed that the HDPE and PP samples had had a homogeneous single-phase structure in contrast to the composite samples with filler from mixed plastic and paper waste. The latter, have a biphasic heterogeneous structure in which the cellulose particles are uniformly distributed. Determinations performed through the dielectric spectroscopy technique indicated that the cellulose content of the composite samples leads to a systematic increase of the dielectric losses (up to about 40% for the HDPE samples, respectively about 30% for the samples with PP), the increases being in direct correlation with the cellulose content of the composite.Mechanical determinations have shown that the average values of tensile strength recorded on the achieved samples, systematically decrease at the increase in the chips content of the samples - decreases up to 10% at an addition up to 15% chips from the waste are explained by the substantially lower mechanical strength of waste paper than that of the HDPE, respective PP.
The Issue of Plastic and Microplastic Pollution in Soil
Authors: Tudor Valentina Constanta , Mocuta Dorina Nicoleta , Teodorescu Ruxandra Florina , Smedescu Dragos Ion
Published: January 2020

Soil pollution with plastics represents a great threat to plants, animals, but especially to humans, as a very small quantity of the plastic which is discarded daily is recycled or incinerated in waste facilities, much of it reaching landfills where their decomposition lasts up to 1000 years and during this time the toxic substances penetrate the soil and the water. If, initially, the pollution with plastics has been identified and recognized in the aquatic environment, recent studies show that plastics residues exist in huge quantities in the soil. The present study focuses on the analysis of factors that pollute soil, so the various studies that have been carried out claim that soil pollution with plastic is much higher and increases in an aggressive manner, being estimated to be 4 to 23 times higher than water pollution with plastics, and the accumulation of microplastics in the soil has a negative impact on soil biota. Thus, once the plastic material accumulates in the soil, it is assimilated to organic matter and the mineral substitutes of the soil and persists for several hundred years.
Numerical and Experimental Study on the Locally Blast Loaded Polyurea Coated Steel Plates
Authors: Bucur Florina , Trana Eugen , Rotariu Adrian
Published: January 2020

The damages and casualties inflicted by mine and IED attacks in security challenging areas generated a strong and quick response from nations all over the world. As a part of this response several national and private research facilities increased their efforts in identifying and implementing new ways or technologies to enable blast wave mitigation. The current paper aim to investigate the opportunity of using polyurea coated steel plates as a possible new blast mitigation approach, as suggested by several investigators. In order to objectively conclude about the ability of polyurea coated plates to sustain locally blast loads several experimental tests were performed according to STANAG 4569 demands for a 1/6 scaled plate structure. In order to numerically validate the experimental results several Autodyn simulations were set-up. The numerical and experimental results exibits a fair correlation, both pointing towards a dismiss of the idea of using polyurea coated steel plates as structural and cost effective blast mitigation approach.
Wear Resistance Under High Load Forces of Four Different Polyethylene Terephthalate Glycol Vacuum-Formed Orthodontic Retainers
Authors: Bratu Dana Cristina , Vinatu Vlad Florin , Pop Silvia Izabella , Petrescu Pompiliu Horatiu , Simon Catalin Petru , Popa George
Published: January 2020

The aim of our study was to determine the wear resistance of vacuum-formed retainers (VFRs) made out of polyethylene terephthalate glycol (PETG), from four different manufacturers (Essix, Leone, Erkodent, Bio-Art), under high load forces (600 N), for 10000 cycles. Forty thermoplastic sheets were divided in four groups, each group consisting of a set of ten sheets from each manufacturer, thermoformed on two matching study models with an ideal occlusion. The Instron 8874 equipment was used to simulate the accelerated wear of VFR surfaces. The surfaces of the VFRs were visually inspected using a KEYENCE VHX-600 digital microscope, but this proved difficult because of the surface shine. 3D models were generated using a GOM industrial laser surface scanner. Several wear areas were identified, having various degrees of roughness, with no evident tear points or perforations. One-way ANOVA analysis showed no statistically significant differences in net mass loss between the four groups.
Poly(ethylene Glycol) Diacrylate-Nanogels Synthesized by Mini-emulsion Polymerization
Authors: Radu Anita Laura , Gavrila Ana Mihaela , Cursaru Bogdan , Spatarelu Catalina Paula , Sandu Teodor , Sarbu Andrei , Teodorescu Mircea , Perrin Francois Xavier , Iordache Tanta Verona , Zaharia Anamaria
Published: January 2020

New nanogels (NGs) with tailored properties were obtained using a mini-emulsion technique, from poly(ethylene glycol) diacrylate (PEGDA) self-crosslinking macromers of various molecular weight. By modifying synthesis parameters (hydrophilic-lipophilic balance, emulsifier and the ratio of organic-aqueous medium), optimum recipes of NGs were selected. Therefore, the molecular weight distribution and the functionalization degree of the PEGDA2000 macromer were assessed by Gel Permeation Chromatography (GPC) and Nuclear Magnetic Resonance (NMR), respectively. Furthermore, the PEGDA-NGs were investigated by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) for size distributions and morphology. DLS and TEM results confirm that these new PEGDA-NGs hold potential for biomedical applications.
Bone - Graft Delivery Systems of Type PLGA- gentamicin and Collagen - hydroxyapatite - gentamicine
Authors: Ionescu (Filip) Oana , Ciocilteu Maria Viorica , Manda Costel Valentin , Neacsu Ionela Andreea , Ficai Anton , Amzoiu Emilia , Stiolica Adina Turcu , Croitoru Octavian , Neamtu Johny
Published: January 2020

The purpose of this study was the synthesis of two types of biodegradable materials with synthetic polymers (PLGA) or natural polymers (collagen) and hydroxyapatite, followed by determination of the encapsulation percentage of the drug in the polymer. Regardless of the chosen method, the percentage of the encapsulated drug was found to be quite high: 15.92% in the Coll-HA-Genta material and 19.59% respectively in the PLGA-Genta biocomposite. The therapeutic value of gentamicin was improved by encapsulating it in delivery systems, contributing to sustained release for a long time (about 30 days).
Experimental Investigations Regarding the Behaviour of Composite Panels Based on Polyurea and Kevlar or Dyneema Layers Under Blast and Fragments
Authors: Iftimie Bogdan , Lupoae Marin , Orban Octavian
Published: January 2020

This paper presents an experimental study to determine the behaviour of composite panels, made of polyurea sprayed on Kevlar or Dyneema support layers, under blast and fragments produced by an improvised explosive device (IED). The fragments used for tests were steel bearing balls of 8 and 10 mm propelled by a plastic explosive charge and bullets cal. 7.62 mm, type Full Metal Jacketed Armor Piercing (FMJ AP) and Hollow Point Boat Tail (HPBT), with impact velocity greater than 500 m/s. To determine the fragments attenuation, their velocities before and after the impact with the composite panel were measured and compared. In order to assess the blast attenuation, the reflected pressures measured by two face-on sensors, one of which was covered by the composite panel, were compared. Also, to explain the behaviour of composite panels under blast, the shock polars of materials in the panel�s composition were plotted. The results have shown that the composite panels have a low rate of attenuation of fragment velocities but a very good ability to attenuate the pressure and impulse associated with the shock wave.
Evaluation of Mechanical Parameters at Compression Test for Different Restorative Composite Resins
Authors: Gamen Andra , Iovan Gianina , Stoleriu Simona , Pancu Galina , Nica Irina , Georgescu Andrei , Taraboanta Ionut , Andrian Sorin
Published: January 2020

The purpose of the present study was to evaluate the mechanical parameters at compression tests for two different restorative composite resins. The materials here under study were: Gradia Direct (GC Corporation, Tokyo, Japan) and Filtek Ultimate Universal Restorative, (3M ESPE, St. Paul, MN, USA). 30 cylindrical samples, 15 for each material, with a thickness of 6 mm and a diameter of 5 mm, were made. The compression behavior at mechanical tests for each sample was analyzed. One-Sample Kolmogorov-Smirnov Test followed by Paired Samples t-Test was used for statistical analysis and determining the level of significance. Gradia Direct had a lower value of Young�s modulus than Filtek Ultimate Universal Restorative, the results being statistically significant (p = 0.001 [ 0.05). The comparative evaluation of the compressive strength did not reveal statistically significant results between the two materials (p = 0.098 ] 0,05). Regarding the compressive strain the values were significantly lower for Filtek Ultimate Universal Restorative (p=0.000 [ 0.05). The microhybrid composite evaluated in the present study proved to have better mechanical properties than the nanofilled composite.
Studies on the Abrasive Wear Behaviour of the Direct Restorative Dental Materials
Authors: Luca Odette , Vitalariu Anca , Cioloca Catalina Holban , Tatarciuc Monica , Popa Diana Diaconu
Published: January 2020

Modern coronary restorative materials have a vulnerable aspect, represented by the excessive wear, which determines the severe limitations of applications in the areas of the occlusal contact. In this study, the experimental researches on the abrasive wear behaviour were performed on five direct restorative dental materials belonging to some different classes from the structural point of view: compomer (Compoglass), ceramic (Empress), silver amalgam (Ventura Plus), poly-glass (Artglass), light-cured lining composite resin (Herculite 1). The analysis of the abrasive wear behaviour of direct restorative dental materials imposed their initial characterization from the microstructural point of view and according to the Vickers hardness. Experimental determinations pointed out absolute and relative mass loss, mass intensity and wear speed. The results of the study are useful in choosing a direct resistant and esthetical restoration material.
The Sintering Behaviour and Mechanical Properties of Hydroxyapatite - Based Composites for Bone Tissue Regeneration
Authors: Tecu Camelia , Antoniac Iulian , Goller Gultekin , Yavas Baris , Gheorghe Dan , Antoniac Aurora , Ciuca Ion , Semenescu1 Augustin , Raiciu3 Anca Daniela , Cristescu Ioan
Published: January 2020

The developement and regeneration of healthy bone tissue is a complex process that includes the interaction of different cell types and requires a set of coordinated processes. The loss of bone tissue may occur due to various reasons: surgical removal, bone trauma (i.e., fractures) or systemic bone loss (i.e., osteoporosis). When the natural bone tissue is destroyed, the regeneration capacity of the bone is not always satisfactory. The result consists therefore in many functional and structural aberrations. In order to improve and accelerate the healing process, bone substitutes have been developed. Hydroxyapatite has been widely used in bone applications due to its excellent biocompatibility, osteoconductivity and bioactivity [1,2]. The objective of this research is to obtain a new composite biomaterial that can be used as bone substitute. In this study, bovine hydroxyapatite obtained from freshly calcined bovine femur was used. The objective of this research is to obtain a new composite biomaterial that can be used as bone substitute. The experimental composite samples were obtained using bovine hydroxyapatite as matrix and tricalcium phosphate, respectively, magnesium oxide as reinforcement materials. The synthesis process of these new biomaterial composites, the effect of chemical composition, surface structure, chemical and phase composition as well as mechanical features have been investigated.
Natural Polymeric Beads for Encapsulation of Stellaria media Extract with Antioxidant Properties
Authors: Miere (Groza) Florina , Teusdea Alin Cristian , Laslo Vasile , Fritea Luminita , Moldovan Liviu , Costea Traian , Uivarosan Diana , Vicas Simona Ioana , Pallag Anamaria
Published: January 2020

Natural polymers are biodegradable and biocompatible and can be used as carriers of pharmaceutical active compounds, with good results for the enhancement of their stability characteristics.Plant extracts of the Cariophyllaceae family are of great interest due to antioxidant, anti-inflammatory, carminative, anticancer, antibacterial, antifungal, antiviral properties, and more recently, the ability to inhibit intestinal carboxylation and reduce obesity by complex mechanisms.The aim of our study was tocharacterize the Stellaria media aqueous extract from the point of view of total polyphenols (using Folin-Ciocalteu method) and antioxidant capacity, as well as the efficiency of inclusion of Stellaria extract in calcium chloride alginate beads by two different methods. In the same time, the size of alginate microcapsules was investigated along with the released efficiencyfrom the polymeric matrix in different biological fluids.Two different methods for encapsulation of Stellaria media extract were developed in this work, using calcium alginate beads. Encapsulating efficiency shows a better approach within the method in which the extract was in situ encapsulated in �pearls�-shaped beads.
Decreasing the Mass of Turbomachinery Subansamblies Using Advanced Polymer Composites
Authors: Maier Raluca , Vintila Sebastian , Mihalache Radu , Vilag Valeriu , Sima Mihail , Dragan Valeriu
Published: January 2020

The extension of use of light advanced polymer composites from structural parts of an aircraft to all kinds of components of the engine is presently very limited by the knowledge of both technological development process and materials behaviour during service. The paper comes to meet an area of interest for many researchers and large integrators and manufacturers, by presenting the first steps made into the manufacturing of a carbon fiber reinforced composite blades for a centrifugal compressor impeller. An existing metallic reference impeller was redesigned, air flow studies were achieved to establish new design performances, precursors (type, volume fraction, architecture, distribution) were defined for the CFRP (Carbon Fiber Reinforced Polymer), stress analyses were performed on proposed structural materials configurations. Furthermore, the paper award an important section to manufacturing process stages, the manufacturing technology used and first developed trials. It was concluded that an entire impeller CFRP (Carbon Fiber Reinforced Polymer) manufacturing can and shall be the next step of the study, using autoclave technology.