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This paper presents the influence of the grinding percentage on some electrical properties, when the process of injection is used in the production of technical commodities, made of polyamide 6.6 (PA 6.6), polyoxymethylene (POM) and acrylonitrile butadiene styrene (ABS), for different industries. The specimens produced had the following compositions: new material 100%, new material 80% + grinding 20%, new material 60% + grinding 40%, new material 40% + grinding 60%, new material 20% + grinding 80% and 100% grinding. The measurement of the electrical properties was carried out using the methods for the determination of relative permittivity and of the dielectric dissipation factor, with the method of zero by Schering bridge. It was found that increasing the percentage of grinding in samples, from 0% to 100%, determined a slight increase in the values of relative permittivity at all three polymers tested and the increase of measurement frequencies for acrylonitrile butadiene styrene and polyoxymethylene led to insignificant changes in the values of relative permittivity, while in the case of polyamide, increasing the measurement frequency led to a slight decrease in the values of relative permittivity. It was also found that increasing the proportion of grinding in the specimens, from 0% to 100%, determined a slight increase in the values of the dielectric dissipation factor in the case of polyamide and polyoxymethylene, while in the case of acrylonitrile butadiene styrene increasing the percentage of grinding in the samples resulted in insignificant changes. The increase in the measurement frequencies for the three tested polymers resulted in a decrease in the values of the dielectric dissipation factor.

Extending of the welding application field by high frequency currents of the thermoplastic polymers requires the full knowledge of the physical parameters which characterize the joining process of the welded joint. Since these engineering materials are extremely sensitive to temperature variations, the present paper highlights the role of the thermal gradient in obtaining of some welded joints with high mechanical strength and free from continuity defects. Regarding this, it is demonstrated that increasing the thickness of the polyvinyl chloride films, from 0.4 to 1 mm, the heat effect in the contact area of the electrodes is kept and the welding process has a high stability. For a well-run welding process is obtained a uniform distribution of the molten material in the joint area with positive impact on the breaking force values.

Using the reliability accelerated tests in the early stage of solar cells life cycle, by using an high level of stress, in order to highlight the one or more degradation factors, on which could be quickly acquired a series of the experimental data, leads to point out the design errors of solar cells and to predictive assessment of reliability indicators. Environmental factors influence the lifetime of a solar cell. The action of each factors determines its aging and finally its degradation as the result of the combined action of sunlight, emissions, climate change, temperature and humidity, the action of dust, the saturated air from the proximity of oceans and seas, whose actions a solar cell undergoes during normal operation. In this paper has been analysed 10 polycrystalline solar cells subjected to accelerated corrosion tests. It has been also carried out two analyses, the first a quantitative analysis by determining the values of reliability indicators and the second one was a qualitative analysis of the degradation of polycrystalline solar cells using the optical microscope.

Obstructive sleep apnea syndrome (OSAS) in children is characterized by recurrent events of partial or complete upper airway obstruction during sleep. Functional orthopedics has been used for patients who have OSAS and craniofacial anomalies because they change the mandible posture forwards, improving the respiratory function. In present, much attention is accorded to the relationship between respiratory function and facial morphology. This study combines the cephalometric measurements and cardio-respiratory polygraphy, in order to analyze the effects of a modified functional Twin Block polymeric appliance on respiratory variables in OSAS patients. The chief complaints of the included in study patients was the crooked teeth and the teasing about their smile. Pretreatment facial photographs show labial position of anterior teeth, gummy smile, a large overjet, incompetent lips and retrognathic mandible. The patients underwent overnight cardio-respiratory polygraphic tests in the same Sleep Laboratory, before and after mandibular advancement device treatment. At the end of the orthopedic treatment phase, the beneficial result of this study was the mandible correction, the maxilla restrained, over jet decreased, improving the facial profile and reintegration of the patient in the school social environment. The education of the parents and of the small patients to recognize the symptoms of sleep apnea and to apply the available effective treatments with a positive social impact on self-esteem and which recovers the facial aesthetics and functionality is a stringent necessity.

Maxillary obturator prostheses are dental devices used to close palatal defects created by surgical resection of different type of tumors, congenital malformation or trauma. The most popular material used for denture fabrication is the polymethyl methacrylate (PMMA). In recent years thermoplastic resins has attracted attention as a denture base material. This paper presents experimental compression and traction tests of VertexTMThermoSense from Vertex-Dental B.V. VertexTMThermoSense is a thermoplastic material based on a compounded mixture of Polyamide and pigments used in the fabrication of removable full and partial dental prostheses. Test results show that the average compressive yield strength of the samples is 60.18 MPa. The result of the tensile test showed an average of 49.4 MPa yield strength. VertexTMThermoSense has a very good average of the yield strain of 10%. The average of Young modulus is 1050 MPa.

This paper presents the reinforcement effect of bentonite (0 – 30%) on styrene-diene block-copolymers in correlation with the biphasic morphology of these thermoplastic elastomers.

Tooth bleaching and other cosmetic treatments (performed at home or in the dental office) are very common nowadays. The use of thermoplastic materials for the manufacturing of whitening trays should have good biomechanical properties in order to assure a good treatment outcome with a good esthetic result. The most common tray manufacturing material is an acrylic poly-resin thin foil that can be vacuum-formed in order to fit any clinical situation. The material must be inert in order to prevent harmful free radicals release form the interaction with different bleaching substances. Thermoformed trays were manufactured in our dental office and immersed in a mixed oral suspension (that also contained artificial saliva) in order to test the behavior of the material in the intraoral environment.

The present research was made by following three directions: dissection and plastination, clinical ankle joint ligament injuries and MRI and CT examination of the cases.191 cases of ankle joint ligament injuries have been studied during two years. They were examined clinically and radiologically, using CT and MRI testing. The classification of ankle sprain was based on the number of injured ligaments. Out of the 191 cases diagnosed with ligament injuries, 92 involved the anterior talofibular ligament, 54 in the calcaneofibular ligament, 40 involved the posterior talofibular ligament and 5 involved the deltoid ligament. First degree sprain involves the injury of the anterior talofibular ligament, the second degree sprain involves the injury of the anterior talofibular ligament and of the calcaneofibular ligament, and the third degree sprain involves the damaging of anterior and posterior talofibular ligaments, as well as the calcaneofibular ligament. In this paper we have diagnosed a number of 39 first degree springs, 12 of second degree springs and 41 of third degree springs. The standard X- ray examinations have a low diagnostic rate of the ankle ligament injuries. Conventional MRI has a higher accuracy in diagnosing ankle joint collateral ligaments lesions.

The paper presents the results of research for magnetic composites made of metallic filler from alloy Fe65Co10Ni3W2B20 and epoxy resin EPIDIAN 100. The composites studied contained less than 10% of the resin, making them dimagnetoelectrics. The structure of alloys and composites was investigated using X-ray diffraction and scanning electron microscopy and their magnetic properties using a vibration magnetometer. It has been shown that the structure and properties of the composites depend on the chemical composition of the metallic filler. And good link between components, with the proper placement of the filler in the matrix, has an impact on the quality of the composite.

This article describes the evaluation of molecularly imprinted polymers (MIPs) obtained by wet phase inversion for facile separation of hypericins from Hypericum perforatum L. (or Saint John’s Wort, SJW). In this respect, concentrated extracts containing hypericin and pseudohypericin were used as “phyto-templates” for creating selective cavities into the pearl shaped MIPs. The obtained MIPs were characterized by infrared and by thermal analyses. Chromatographic evaluation of the MIPs was performed relative to blank samples and it was concluded that the pearls can retain selectively the hypericins from SJW extracts.