Browse Articles

Film forming polymer solutions for skin wound dressing were developed and characterized. Film forming solutions were prepared by adding polyvinyl alcohol (PVA) and poly (hydroxy) urethane (PHU) in different proportions into a well tolerate volatile solvent. The formulations were in vitro evaluated according to five criteria. Two formulations have proved the ability to form polymeric film. Evaluation of the tensile strength, contact angle and swelling index were made for these formulations. The results showed a positive response of the formulations to be used for skin wound dressing. Keywords: integrity on skin, swelling index, tensile strength, surface polarity

The challenge of the chondral lesions treatment has been considerably answered with the development of non-cellular scaffolds. Among the most frequently used, the scaffolds based on Hyaluronic Acid and, respectively, collagen derived polymers are the subject of our comparative research. The present paper highlights some particularities related to their intrinsic physical properties such as adhesiveness, microstructure and cellular permeability and concludes that the two alternatives present qualitatively similar outcome and effectiveness. Keyword: hyaluronic acid polymer scaffold, collagen scaffold, chondral lesions, osteoarthritis

The mechanism of action and adverse reactions of 52 mg levonorgestrel-releasing intrauterine system and also level of pain during the insertion and techniques of anesthesia or analgesia for this procedure have been well documented. On the opposite pole the 13.5 levonorgestrel-releasing intrauterine system has been recently launched in Europe. To our knowledge there are no studies correlating the device design and biomaterials, mechanism of action, surgical technique and level of pain during the insertion of levonorgestrel-releasing intrauterine systems. This study was undertaken in order to determine whether there is a different level of pain during the insertion of 52 mg levonorgestrel-releasing intrauterine system compared to 13.5 mg levonorgestrel-releasing intrauterine system, considering the mechanism of action and the structural and dimensional discrepancies between the two intrauterine devices. Keywords: Levorgestrel-releasing intrauterine systems, device design, mechanism of action, level of pain during the insertion

The liver segmentation is determined by the distribution of the vascular and ductal hepatic elements; from this, the hepatic portal vein (HPV), the central element of liver afferent pedicle, is the most important. The posterior branch (PB) is serving right lateral division (RLD) of the liver and presents the lowest morphological variability. On a total of 125 pieces of liver corrosion casts, one examined the intraparenchymal distribution of portal PB and the segmentation of RLD. Regarding the intraparenchymal distribution of the branches in the RLD of the liver, we showed four distinct morphological types: Type I (77.6% of cases) in which the PB bifurcate symmetrically in branch of segments VI and branch of segment VII; Type II (8.8% of cases) in which the PB bifurcate in branch of segment VII and an inferior branch, that bifurcate branch of segment VI and branch of segment VIA; Type III 12.8% of cases) in which the PB bifurcate in branch of segment VI and a superior branch, that bifurcate in branch of segment VII and branch of segment VIIA; Type IV (0.8% of cases) in which the PB trifurcate in branch of segment VI, branch of posterior intermediate segments, and branch of segment VII. Knowledge of these morphological types of portal PB is important for clinical and surgical practice. Keywords: corrosion casts; hepatic portal vein; posterior branch; variability; morphological typologies

Fiber reinforced composites (FRC) are used in periodontal therapy for stabilization of mobile teeth with compromised bone support. The type of fiber and the type of composite have a great influence on mechanical properties of FRC. The specimens made of different FRC systems were subject to a three-point bending test. The results indicate that the specimens which exerted the best ratio between high deflection, low flexural modulus and medium flexural strength have the best indications to be used in periodontal therapy. Regarding the fracture pattern, the FRC recommended for splinting are those that separate in two discrete parts while maintaining an intact polyethylene fiber. This aspect allows intraoral repairs, increasing the life-span of the periodontal splints. Keyword: fiber reinforced composite, periodontal splint, three-point bending test

The purpose of this study is to assess the effects of artificial saliva with different pH on the wearing of glass ionomer cements. We used three types of glass ionomer cements and three immersion environments. We have prepared a total of 96 samples. We used 6 artificial saliva samples for each environment. Each sample was immersed in the storage solution to a specific pH. Storage solution was changed on days 1, 7, 14 and 28. Glass ionomer cements are influenced by the storage media, showing significant changes in the case of an acidic environment (in our case, artificial saliva with different pH). As long as the material is tolerated and protected by the tooth structure, resistance to abrasion will be satisfactory. Keywords: glass ionomer cements, pH, artificial saliva, wearing

A number of inventions, and theoretical and experimental research allowed to increase the thermal homogenous melt flow-rate delivered by the screw. On the other hand, quality of the extruded product depends on geometrical considerations of the extrusion head and on a large scale on the rheological behaviour (viscous and elastic) of the polymer melt. Non-harmonizing the design of the screw-barrel unit with the construction of the extrusion head can lead to low-quality products. In this paper, the extrusion head working field was drawn based on limitations imposed by the screw-barrel unit, i.e.: maximum flow-rate assuring required melt thermal homogeneity; - maximum flow-rate for which the heating system on the barrel (and screw, eventually) assures the extrusion temperature; -minimum flow-rate corresponding to screw diameter. Keywords: extruder head working field, extruder performance, rheological behaviour, screw-barrel unit

The spectral shifts in the visible electronic absorption spectra of B3 in water-ethanol mixtures were correlated with the macroscopic parameters (refractive index and electric permittivity) of the solvents. The contributions of the intermolecular interactions upon the spectral shifts as a function of the solvent macroscopic parameters were expressed by multiparameter regressions. The dependence of the wave number in maximum vibronic band of B3 vitamin on the solvent macroscopic parameters demonstrates the prelevance of the orientation interactions in the studied solutions. Some electro-optical parameters and global descriptors of B3 vitamin were computed by Spartan program. In present, the assimilation of the B3 vitamin copolymeric compounds in medicine and cosmetics must fullfil the complexity of the biological issues that result from using them. We note that the B3 vitamin can be incorporated in the polymeric structures to improve its functions. Keywords: solvents effects, absorption spectra, B3 vitamin

Protonation, quaternization and addition reactions of poly(N-vinylimidazole) to the imidazole nitrogen atom in the position 3 to obtain the corresponding ionic derivatives were studied by NMR Spectroscopy. Information and data about the reaction type and product microstructure are presented. The chain tacticity is a special structure aspect which was in detail studied by means of proton and carbon NMR spectra confirming that the chain configuration is not modified by any of the three polymer-analogous reactions. Keywords: poly(N-vinylimidazole); polyelectrolytes; benzyl chloride; trifluoroacetic acid; acrylic acid; chain tacticity; polymer microstructure

This paper, intended to continue the previous work under the same title, published in the previous number – aims at presenting the experimental results, obtained by laboratory tests, referring to the influence of the massic percentage of the hemp hurds within the composites, as well as to the influence of the participation percentages of the filling materials (cement, lime, sand, plaster etc.), on the thermal-transfer factor. The experimental results place thereby this composite in a position comparable to other construction materials; which emphasizes the importance of this composite, with a view to its being used as construction material, both as boards (for lining) and as blocks (for filling). The analysis of the experimental results shows that this type of composite can be ”programmed” and ”controlled” in terms of thermal-transfer factor, through the massic participation percentage of the hemp hurds. In this way, one can extend the use of these composites over constructions in areas with variable temperature differences, especially in the cold season. Moreover, by these experimental values, one can devise a methodology for sizing the construction elements, based on thermal-transfer factor to be achieved and, implicitly, on the thermal insulation capacity to be provided by the respective construction. Keywords: composite, hemp hurds, thermal-transfer factor