This study follows the possibility to tune the thermal stability of some CaCO3/polymer composites by crystal growth from supersaturated solutions controlled by polymer structure or by using nonstoichiometric polyelectrolyte complexes (NPECs). As the ratio between the organic and inorganic parts in the composites controls the Ca2+/polymer network crosslinking density, the CaCO3/polymer weight ratio was kept constant at 50/1, varying the initial concentration of the polyanions solutions (0.05 or 0.06 wt.%), the NPECs molar ratio , n+/n- (0.2 or 0.4), or the inorganic precursors concentration (0.25 or 0.3 M). Poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylic acid) (PSA) and chondroitin-4-sulfate (CSA) were used as polyanions. Some NPEC dispersions, prepared with the same polyanions and poly(allylamine hydrochloride) (PAH), were also used for calcium carbonate crystallization. The characteristics of the prepared composites were investigated by scanning electron microscopy (SEM), flow particle image analysis (FPIA), particles charge density (CD), zeta-potential (ZP). The thermal stability of the composite particles was investigated as compared to bare CaCO3 microparticles prepared at the same initial inorganic concentrations.
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The paper presents the structural analysis of cast iron fragments from the cylinder coat of a combustion engine, as a result of the broken down through explosion. Initially, determinations of the chemical composition were made and it was found that although the cast iron had the carbon content imposed. As a result, detailed microstructural analyzes were made regarding the shape, size and distribution of graphite in the cast iron as well as for the identification of structural constituents and constitutive phases. The same investigations were carried out on samples taken from a cylinder coat with a good functioning for comparison (blank samples). The metallographic study revealed characteristics of inappropriate graphite separations (graphite type B, D, E) and areas with specific structural constituents to the mottled cast iron that can cause breakage of the cylinder coat and excessive wear of the segments.
UV radiation has a long-term effect on the durability of anti-corrosive coatings applied by painting, generating conditions for accelerated localized corrosion of the protected metallic structure with adverse effects on operational safety. This paper presents a comparative study of the behavior of some painting materials ageing by exposure to UV radiation relevant by the investigation of dielectric behavior using dielectric spectroscopy in conjunction with the thermal stability investigated by coupled techniques of thermal analysis. From a practical point of view, the UV radiation behavior of two materials based on epoxy resins and polyurethane resin used as paints for protective decorative coatings was studied. The results of experimental investigations have shown that in the aging process of the studied painting materials there is a direct correlation between the evolution of the maximum temperature characteristic of the first thermooxidation process and the evolution of the dielectric performances (dielectric loss – tgd).
The objective of the study is the low-pressure membrane process for treating aqueous solutions containing synthetic food dye (E104 – quinoline yellow). Dye concentration used was 10% (equivalent to 100g/m3). The pressures used in the ultrafiltration process were 0.1, 0.2 and 0.3 MPa. Experiments were performed in dead - end instalations in which the effectiveness of the polysulfone - alkylbenzyldimethylammonium chloride (PSU-ABDMA) and polysulfone - N-dodecylpyridinium chloride (PSU - NDPCl) were tested. The efficiency of these membranes has been proved by calculating the permeate flow and the retention. Analyzing the experimental data, it was found that for the polysulfone-alkylbenzyldimethylammonium chloride composite membrane the degree of retention is completely different, with high values being obtained for low pressures and low values for high pressures used.
The present paper presents the results of the research regarding the bolus structure (Bio-Rad Win-IR instrument), the elasticity modulus, the bioadhesiveness properties (TA-XT2 Plus analyzer) and the clinical applications of the bolus in the adjuvant irradiation after radical mastectomy (Treatment Plan System Eclipse). The dose-volume histogram has made a comparative evaluation for with and without bolus treatment plans and confirmed the importance of bolus utilisation in selected patients. Conclusions: the thickness of the applied bolus is dependent on the skin dose required, on the treatment technique and must be equal to the depth of the build-up region for the removal of the skin-sparing effect of a high energy radiation.
The influence of Ag/SiO2 as nanofiller and sodium oleate as compatibilizer and their mixtures on the patterns flow and structure formation processes in thermodynamically incompatible polypropylene/plasticized polyvinylalcohol (PP / PVA) systems were studied. It is found that the change in the sequence of mixing the ingredients of the composition allows adjusting the morphology phase type due to the predominant localization of nanoparticle additives in the melt amount of a component or on the border of phase separation. Injection of Ag/SiO2 to melt PP increases dispersion degree and homogeneity of its distribution in the matrix. Simultaneous use of nanoadditive and sodium oleate as compatibilizer improves the connections between the polymers and promotes thinner and more homogeneous dispersion of the particles of the dispersed phase. It is shown that the effective viscosity of melt nanofilled system is determined by components mixing method: viscosity of melt blend increases when the additive is localized predominantly in the PVA and decreases with the prior injection of PP. The nature of the flow for all researched compositions obeys a power law and almost does not depend on the method of mixing. The ability of the longitudinal deformation of ternary blends is deteriorating, but remains sufficient for their processing. Combining nanoadditive with compatibilizer promotes increased elasticity and the melt spinnability of modified blends.
Root decay is a complex and multifactorial disease. The aim of this study is to assess in vitro the sealing capacity of common aesthetic materials used to restore root caries as well as the size of the hybrid layer formed by SE-1 step vs 2-step ER adhesive techniques. For this study, 45 extracted teeth were used. After cleaning, near the enamel-cement junction, but at the level of the cementum, cavities were prepared and restored with resin composite, giomer and glass-ionomer cements. The teeth were covered with nail polish leaving uncovered the restoration area and 2mm around it; teeth were kept for 24 h , in 2% methylene blue. To assess the degree of marginal adaptation, SEM analysis was further performed. The association of 2-step ER adhesive system with giomers and resin composite shows the maximum adhesion efficiency by forming a uniform, thick layer and dentinal tubules obliteration compared to SE-1 step adhesive system associated with the same restoration materials.
A moment of permeation of both gaseous and liquid phases of a toxic compound through a barrier material has been indicated colorimetrically at the same time on 20 exposed places using suitable colour indicators. The newly developed device MINITEST is able to evaluate the resistivity of both porous and non-porous barrier materials of a textile character against permeation of toxic vapours (permeation) and liquids (penetration) in static conditions. As a model test chemical either the sulfur mustard or significantly alkaline or acid volatile toxic compound have been applied. During the permeation, these species react with a suitable acid-base indicator and a markedly coloured stain can be created. Newly developed MINITEST device enables determination of chemical resistance of areal barrier materials not only in a process of their development but also in the rate of their practical applications.
Procalcitonin was proposed to have been a more specific and better value compared to CRP as a marker of prognosis, although its diagnostic value is also contested.This study was conducted in the Department of Neonatology and the Department of Obstetrics and Gynecology of “Pius Brînzeu” Emergency County Hospital Timisoara on a group of 20 newborns coming from 20 mothers that have been found with low procalcitonin. The gestational age at birth was 36-39 weeks. PCT values do not correlate and do not indicate correctly viral infections. Serum PCT levels must be interpreted within the clinical setting; there are many other causes that could lead to its growth. Our study consists of two different parts. In the first part we computed a regression model in order to see if there is any association between the vales of procalcitonin obtained from the blood analysis of the mother and the procalcitonin of her child.
Traditionally, removable partial dentures consist of a metallic framework, covered by acrylic saddles, which support acrylic or ceramic teeth. Because their shortcomings, new classes of resins/macromolecular compounds which promise better quality are nowadays available for manufacturing removable partial dentures: urethane-based resins, polyamides, acetal resins, high-performance polymers. Manufacturing these new materials implies alternative technologies like: injection, milling, light-curing. Using these alternative polymeric materials results in dentures with better resistance, elasticity, appearance and lower weight, which provide much more comfort to the patient.