Volume 55, Issue 2

Abstract: In the present paper, the authors dealt with the synthesis and characterization of a new type of dynamic membrane with polysulfone matrix and ionic polymer electrolyte: polysulfone-sulfonated polyetherether-sulfone (PSf-SPEEK). The PSf-SPEEK composite membranes were formed by ultrafiltration of SPEEK gel on the polysulfone matrix in a CELFA System installation. The thickness of the PSf porous layer for the different membranes can be between 50 and 120 mm. The variation of SPEEK active layer’s thickness is dependent both on the concentration of the SPEEK solution in the feed, and on the velocity of the surface flow. The sulfonated polymer (SPEEK) superficial layer ranges from 35 to 75 nm, being thicker at low flow rates having a slight increasing related to the increase of the SPEEK concentration. Increasing the polymer concentration, from 0.5 to 2.5%, used in the feed solution leads to a doubling of the conductivity and a tripling of the ion exchange capacity. The maximum conductivity of the PSf-SPEEK dynamic composite membranes is 0.234 S/cm and the ion exchange capacity is 1.682 meq/g.

Abstract: The paper describes the advantages of material deposition using the resistive vaporization method, so that new very thin layer, which is about ìm, could be used on polymer base structure. Due to the new properties involving the friction coefficient on plane surface, where some dynamic forces are acting, we may better control the performances. By analyzing the theoretical aspects of entropy rate production, we may determine the maximum friction providing the stability of wear avoiding the material deterioration during the process.

Abstract: The increasing proportion of laparoscopic interventions in the surgical centers has, also, determined an increased incidence of specific complications, such as trocar hernia. Nowadays, there is no unanimously agreed concensus regarding the optimal closure technique of the trocar incision, wether it should include the suture of the aponeurosis or not at the 10 mm ports. There is, also, no consensus regarding the proper surgical technique for the trocar hernia repair- alloplastic or tissue repair technique.The purpose of the study is to present our experience on the alloplastic repair of the trocar hernias. It is a retrospective study that analyzes the results obtained by our clinicalteam regarding the alloplastic repair of the trocar hernias, over a five-year period, between January 2011 and December 2015. The recurrence and the occurrence rates of different complications (seroma, neuroma with postoperative pain, parietal infiltration, infections and mesh rejection), depending on the type of mesh used for the surgical repair,are studied.

Abstract: Natural mixtures based on bioflavonoids, terpenoids, glycosidic compounds, polyphenols, anthocyanins and essential fatty acids are often more effective and non-toxic than many synthetic drugs. Betulin, a terpene compound with many key-roles in alternative medicine, is almost insoluble in water due to its pentacyclic structure. Different drug carriers are developed to improve the drug efficacy and release. This paper described the evolution of some skin parameters (transepidermal water loss, erythema and stratum corneum hydration) after a short and respectively a long exposure to a polyurethane carrier with and without betulin using sodium lauryl sulfate as reference. It was found that these compounds are safe for human use and the hydratant effect of betulin was reconfirmed.

Abstract: Postoperative eventration is a quite common condition in patients with clinical records of abdominal surgery. The purpose of this study was to investigate the efficacy of use of 2 different types of meshes (Polypropylene mesh and ProGripTM mesh-self-gripping mesh) in the surgical treatment of incisional hernias. In this respect, we conducted a study in which we introduced 128 patients operated for incisional hernias. Patients were divided into 2 lots: group A (102 patients with polypropylene mesh) and group B (26 patients with ProGripTM mesh). From the analysis of the data studied, we noticed that the average duration of surgery and hospitalization for patients with ProGripTM mesh is lower compared to patients with polypropylene mesh. Also, the rate of local postoperative complications was lower when using the ProGripTM mesh (15.38%) than in the case of polypropylene mesh. In conclusion, we can state that the use of the ProGripTM heterologous mesh is beneficial in the surgical treatment of patients with incisional hernias. The major advantage of using this type of mesh is given by a shorter hospitalization period for these patients, as well as by a lower rate of local postoperative complications in these patients.

Abstract: In this research, the thermal performance of the hybrid composites with modified epoxy matrix was investigated. The results were compared with those presented by the hybrid composites with homogeneous epoxy matrix. For understand the effects of the replacement of lower specific density glass fabric by higher specific density glass fabric, the thermal properties of the hybrid epoxy composites were determined by comparison to the thermal results of composites reinforced with lower specific density glass fabric with those of the hybrid epoxy materials reinforced with higher specific density glass fabric. Also, the effects on the specific heat and thermal expansion coefficient of the used fabric types in outer sheets of the composites were studied.

Abstract: This paper presents a comparative study with respect to the behavior of some painting materials, used mainly for decorative and protective industrial applications, exposed to a controlled accelerated ageing process by using thermal storage and successive thermal cycles. The evaluation of the structural changes, as well as those concerning the dielectric loss were carried out in a comparative manner, on the initial samples, before any exposure to thermal stresses and during the ongoing process of the thermal treatments applied. As analysis techniques coupled thermal analysis and dielectric impedance spectroscopy have been used. It was found that there is a clear correlation between the structural changes of the investigated materials, particularly in the case of the epoxy materials subjected to the applied thermal treatments and the evolution of the dielectric losses in the material. As a result of these investigations, one may determine the characteristic acceptable zones for the thermal stresses (up to 1300 h of storage and 1500 thermal cycles), anything above these boundaries leading to strong increases in the dielectric losses and hence the deterioration of the materials rendered unfit to be used for the intended purpose.

Abstract: The objective of this in-vitro study was to compare the accuracy, defined as trueness and precision, of two intraoral digital scanners that use different capturing techniques. An experimental reference object consisting of a die was manufactured from a PMMA resin. The reference object was digitized with an industrial CT and was scanned 15 times with each scanner. In order to asses trueness, comparisons were made with the virtual reference model, and for fidelity, the first scan in the series was compared with the following scans. For both fidelity and trueness, the F test and T tests demonstrate that there is a statistically significant difference between the scanners.

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

Abstract: In this paper we analyze the influence of the number of laser pulses on the hardness of the metal. We have shown that the hardness increases with the number of laser pulses due to the increase in the probe surface temperature, especially by increasing the superficial absorption of laser radiation. Optical microscopy was analyzed by the metallographic aspects of the target in OLT 65, Al, Cu, laser irradiated.

Abstract: Laryngeal stenosis represents a serious and challenging condition in the field of otorhinolaryngology. The management of laryngeal stenosis is performed in multiple stages, and numerous surgeries can be necessary to obtain a favorable outcome. We present a specially designed laryngeal stent suitable for patients with stenosis of the larynx, that can be used after CO2 laser resection. The particular shape of the device, the biocompatible material and the autostatic propriety are some important characteristics that improve the tolerability of patients to the stent. The device has multiple advantages that make it a proper therapy method for selected patients with stenosis of the larynx.

Abstract: 3D printing paired with CBCT imaging technology could provide a more individualised approach to orthodontic diagnosis and tratment. The aim of the present study is to asses dimensional differences between the CBCT image and 2 types of 3D printed replicas of an impacted maxillary canine, and to determine whether this method could be used in the future development of customised orthodontic attachments. Ten replicas were printed using the STL file of the impacted canine using two types of resin- five of each, with the same printer. Linear measurements of maximum height, length and width, were made. Mean dimensional erorrs were 0.184 mm and 0.068 mm. The largest discrepancy was in lenght - 0.362 mm. More reasearch is needed, but in this study we obtained printed resin replicas that provide sufficient dimensional accuracy to be used in orthodontics.

Abstract: In the second part of this series polyelectrolyte multilayer capsules consisting of 6 bilayers of PAH/PSS and one layer of magnetic iron oxide nanoparticles namely D12, were fabricated. These capsules had their inner core removed once the 12 layers had been formed. The properties of the D12 capsules (mean diameter, concentration, dye intake and iron content) were analysed and compared with previously manufactured capsules which had the core dissolved after only 6 layers of coatings namely D6. The new sets of capsules had a greater capsule diameter, higher dye intake into the core and a higher iron oxide loading into the capsule layers.

Abstract: The aim of this experimental study is to compare the biointegration and tissue response to different surgical mesh types, inserted in various layers of the abdominal wall of Wistar rats. After 30 days, the rats were sacrificed and the meshes were removed en bloc with the subcutaneous tissue, muscular layer and peritoneum. Tissue response (fibrosis, inflammation) was measured using quantitative and semi-quantitative morphometry. We observed that polyethylene terephthalate 3D mesh induces significantly more fibrosis compared to polypropylene mesh and the fibrosis is absent or minimal in case of the control group. Tissue reaction, including fibrosis, is reduced around the polypropylene mesh. We also observed that fibrosis is more intense towards aponeurosis and peritoneum. We can conclude that the 3D mesh shows better biointegration if it is used in proper circumstances. It’s well tolerated by the organism if sutured to the aponeurosis and preferable with monofilament stitches.

Abstract: ATR / FTIR and DSC techniques have been used to evaluate the thermal stability of some ageing paint materials by heat treatment while immersion in natural ester-based electro-insulating oil. Experimental determinations have highlighted the fact that the investigated paint materials (epoxy resins) have a high oxygen affinity and thus, in closed systems (such as power transformers), they oxidize before coming into contact with the transformer oil. This behavior indicates that the paint layer (suitably chosen) applied on the inside of the transformer vat functions as an antioxidant and results in increasing the thermal stability of the oil.

Abstract: Incisional hernias affects approximately 10-20% of patients with history of abdominal surgery. The purpose of this study was to examine the tissue integration of the polypropylene mesh in patients operated for strangulated incisional hernias to those operated for uncomplicated incisional hernias. For this purpose, we introduced 218 patients with surgical treatment of the incisional hernia with polypropylene mesh. The total number of patients studied was divided into 2 lots: group A consisting of 189 patients with uncomplicated incisional hernia and group B of 29 patients with strangulated incisional hernia. We studied separately the local postoperative complications in the two groups (hematomas, seromas, abdominal wall infections). Although the number of local postoperative complications was higher for group B, the differences were statistically significant only for the incidence of abdominal wall infections. Although the use of the polypropylene mesh in the surgical treatment of strangulated incisional hernias predisposes to a higher risk of local postoperative complications compared to its use in the surgical treatment of the uncomplicated incisional hernias, its use in the surgical treatment of the strangulated incisional hernias is beneficial.

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

Abstract: In this paper, the authors show a part of research works performed on the use of 3D scanners and 3D printers to execute plastic parts with complex surfaces. 3D scanning allows copying of certain surfaces in our environment, based on existing models. Scanned models may represent various objects, made of a wide range of materials: metals, ceramics, fabrics, plastics, leather, organic materials etc. [1]. This paper shows the results achieved using a scanner and a common and affordable - low-price - printer. 3D scanners and printers allow execution of clones of certain parts with irregular surfaces.

Abstract: Structural elements of special industrial constructions can be often subjected to time variable stresses. One of the main stress is the snow action, which is considered to be one of the most severe tests. In the study, the static snow action on a tank cover from a pickling plant on the ArcelorMittal Galaþi platform is analysed. The material structure of the cover is sandwich type with skins made of steel /layered composite and core made of polystyrene foam. The purpose is to determine, by FEM analysis, the deformation mode and the stress condition of the cover under the action of load, for two models of sandwich type structures, steel-polystyrene-steel, respectively composite-polystyrene-composite, with different faces thicknesses and cores. Panels are applied simulative a load of snow of different thickness, the distribution of snow on the surface of the panels being considered uniform in order to determine an optimum combination of faces and core thickness as well weight and economic cost too. Numerical analysis models with finite elements of SHELL 3L sandwich type structures are used.

Abstract: Urinary incontinence is one of the most common diseases, 25% of women between 18 and 80 years suffer from it. Urinary incontinence can be described as accidently loss of small amounts of urine. The solution involves a surgical procedure, such as sling procedures and bladder neck suspension procedures. The methods of surgical interventions have evolved due to a minimum period of hospitalization (sling, TVT), or performing laparoscopic surgery instead of the classical Burch surgery. Studies reviled that the most effective interventions are those which restore the urethra by retro pubic urethropexy, pubovaginal sling and synthetic mid-urethral slings. This type of surgery has currently the highest success rate (85-90% on 5 years after surgery), and the lowest relapse rate. In our study we obtained the same success rate for the TVT procedure.

Abstract: The purpose of this in vitro study is to evaluate the marginal percolation-micro leakage by comparing the possible infiltration of ionomer cement filling which was used to restore a class I cavity prepared by classic conventional method – diamond bur versus Er:YAG laser irradiation treatment. Ten molars were included in this study. The molars were random divided in two groups: group 1 - laser treatment and group 2- classic conventional treatments. The teeth were immersed in methylene blue solution for 24 h. Afterwards, the molars were vestibulo-oral sectioned through the centre of each restoration in order to see any signs of marginal percolation. The marginal percolation observed was more significant in conventional preparations group than in laser’s group. The glass ionomer cement remains one of the most adequate restorative materials to be used on deciduous molars when micro infiltration is questionable.

Abstract: The aim of this study was to evaluate the postoperative effect of one bleaching agent containing 40% peroxide hydrogen on the interface between dental tissues and a microhybrid composite resin bonded with a universal adhesive applied in total-etch and self-etch technique. Standardized Class V restorations were performed in oral surfaces of 40 extracted human molars with the gingival margins placed bellow the cement-enamel junction. For 20 restorations the adhesive was applied with preliminary etching and for the others the adhesive was applied by using the self-etch technique. Half of the samples of each group were bleached using Opalescence Boost in one session 20 minutes-application. The sealing quality of both enamel and cervical margins of the restorations was evaluated using a microleakage test by immersion in 1% methylene blue for 24 hours. The microleakage scores were assessed using an optical microscope and the data were statistically analyzed. No statistical significant differences were recorded between the bleached and control groups and between the study groups according to the etching strategy used for bonding.

Abstract: The aim of the study was to compare the marginal adaptation of three different resin-based materials used for direct restoration: hybrid composite resin (Gaenial Posterio, GC Corporation), a compomer (Dyract eXtra, Dentsply Sirona), and a giomer (Beautifil II, Shofu Dental) applied at room temperature or after preheated at preheating 50 and 60oC. Class II cavities were prepared on proximal surfaces of extracted teeth and randomly divided in 3 groups according to the material used for restoration. In each group five cavities were restored using the materials at room temperature (subgroup 1), five cavities were restored using preheated materials at 50ºC (subgroup 2), and five cavities were restored using preheated materials at 60ºC (subgroup 3). The teeth were stored in distilled water for 14 days and then were immersed in 2% methylene blue buffered dye solution (pH = 7) for 4 hours. The teeth were transversally cut and the sections were examined using optical microscope (Carl-Zeiss AXIO Imager A1m) at 50x magnification and the dye penetration was evaluated according to 4 scores. Decreased microleakage and fewer gap formation were recorded for all filling materials after they have been heated at 50 or 60oC. Pre-warming of resin-based materials improves the adaptation of these materials to tooth structures.

Abstract: It is well known that periodontitis causes rapid destruction of gingival and bone tissues. Topical treatments are suitable because the drug can be delivered in a proper and controlled concentration. Metronidazole proved to be efficient for patients with aggressive periodontitis. By this study we aimed to obtain spongious drug delivery systems for local periodontitis treatment based on collagen, strontium renalate and metronidazole. Collagen spongious forms were obtained by lyophilisation of composite gels based on collagen:strontium ranelate (50:50) and different concentrations of metronidazole. The obtained spongious forms were characterized by FT-IR, water up-take, optic microscopy and in vitro release of metronidazole. The prepared matrices absorbed a maximum amount of water after 30 min. The most absorbent sample is the reference one (only collagen) which absorbed about 35% water; the adding of metronidazole decrease the water absorption due to its lipophilic behavior. The samples with strontium are more compact and they absorbed less water than the ones without strontium. Because the samples were not cross-linked they degrade during 24 hours of water absorption process. The drug percentage released was influenced by the drug and strontium ranelate concentrations. The analysis performed sponges indicate that these composites can be useful as drug delivery supports.

Abstract: The purpose of this research is to establish the technology of 3D printable production on the principle of FDM of gears made of PLA, ABS and PETG mainly. In the paper we present first the dimensional generation and specific aspects that need to be considered to produce gears with internal or external teeth of the cylindrical type with vertical or inclined teeth. Generating the gears appeared as a necessity for the reconditioning of the components of the processing machines and of the electric machines made both in the process of elaboration of the bachelor’s and the laboratory works, with reduced energy resource consumption and low pollution as low as possible. After the construction, we past to identify the dimension that have implications for both mechanical and kinematic resistance to achieve a product with good cinematic and functional characteristics. After that are made an analysis of the layers generated, both from the computer simulation and from the point of view of the analysis of layers physically generated on a gear tooth with external teeth.

Abstract: Specialty literature demonstrates the direct link between gastro-esophageal reflux diseases (GERD) and dental errosion (DE). Patients diagnosed with GERD often shown dental tissue loss in the enamel and dentine, somentimes going as far as opening the pulp chamber. Modern minimal invasive treatments make use of the current performance of cements and prosthetic materials (composites and ceramics) to conserve healthy enamel and dentine, in comparison to classic reconstruction methods.