A challenge of actual research in the field of epoxy resin composites is to find paths to modify the basic properties of these polymers but keeping unchanged their excellent mechanic properties when is about epoxy resins. One valuable way is to find appropriate solvents that are compatible with the used polymer and able to solvate specific salts such as using the solution to place metallic ions inside the polymer matrix. Such an attempt might be followed by solvent removal by various physical processes having as effect the presence of metallic ions in the polymer network with possible effects regarding the transport phenomena. There are some well-known solvents as 1,4-Dioxane, 1-Methyl-2-Pyrrolidinone and N,N-Dimethylformamide that can be used also as metallic complexes precursors and their effect on the properties of an epoxy resin should be known. Present study is concerning with the modifications induced by the use of above mentioned organic solvents together with glucose and starch as an attempt to create nano-structures inside the polymer. For this study three epoxy resins had been used and tribological behaviour had been studied on a TRM 1000 tribometer from Wazau (Germany).
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The aim of our study was to establish the level of calculus and dental tissue loss, together with the quality of the dental root surface after the instrumentation performed by three techniques applied in the causal treatment of the periodontal disease – the Gracey curettes, the ultrasonic scaler and the reciprocating systems with Periotor inserts. The in vitro study was conducted on 33 extracted teeth by periodontal pathological reasons which were randomly distributed in three sample groups: group 1 (instrumentation with Gracey curettes), group 2 (ultrasonic piezoelectric scaling) and group 3 (instrumentation with reciprocating system). The quantitative evaluation of hard tissue loss after instrumentation was done by weighing each tooth before and after performing the procedure. For the qualitative analysis of the instrumented root surfaces we applied the Roughness Loss of Tooth Substance Index (RLTSI). The greatest weight loss in the samples was registered by Group 1 (Gracey curettes), but there were no statistically significant differences between the mean values of the weights between the study groups. The mean values of the RLTSI score were significantly different between groups 1 and 3, with better scores for the reciprocating system. Therefore, the results of our in vitro study revealed the fact that the scaling in deep pockets with the Periotor inserts was the least aggressive method, followed by the ultrasonic scaler and the Gracey curettes.
The aim of this study is to demonstrate that tanned waste leather can be successfully incorporated in cement matrix and the resulted composite material can be proposed as construction material. The composite leaching tests for total chromium (maximum concentration registered = 2.76 mg/kg), which is the most used tanning agent, shown low levels in leachate lower than maximum allowed concentration MAC for non-hazardous waste (MAC = 10 mg/kg). The study proposes a new environmentally friendly recycling method for tanned leather waste.
The effect of zinc oxide-eugenol material (Cariosan, Spofa Dental) on resin-based restorative materials (a composite resin - Premise, Kerr Company, a compomer - Dyract Extra, Dentsply, a giomer - Beautifil, Shofu) hardness was investigated. Surface hardness was evaluated using a digital microhardness tester (Micro-Vickers Hardness System CV- 400DMTM, CV Instruments Namicon). In contact with eugenol-based cement the hardness values of all tested materials significantly decreased. After cement storage in artificial saliva for 1 and 7 days, the hardness values of all three resin-based materials registered a significantly increase when compared to the samples where the materials were placed in contact with eugenol-based cement immediately after setting, but still significantly lower when compare to the samples having no contact with eugenol-based cement.
Wool as important row material in textile processing is the oldest fibre used by people to make fabrics. In order to make products corresponding to market requirements, use of the increasingly fine wool fibres has expanded. This type of fibre is mainly imported. In order to establish optimal conditions for the experiment was chosen a central compose rotatable program, second order, with two independent variables: partial draft and spindles speed at spinning machine. Using data obtained with the program have established the optimum parameters of the spinning process. The paper examines the optimization of the spinning process of a yarn made by 100% wool, sort 70’s Nm 52.
The lack of drug specificity for inner ear structures and the side effects of systemic administration have determined the treatment strategies to evolve from systemic administration to local application of drugs. The disadvantages of systemic or local administration of drugs for the inner ear, have led to the development of nanoparticles with specific activity. The study presents current research advances regarding the use of nanoparticles (liposomes, PLGA, dendrimers, silica or magnetic nanoparticles, etc.) in inner ear pathology treatment.
One important direction for the mechanical behavior study of the materials is the fracture surface evaluation. This work makes a qualitative interpretation of the fracture surface from some Zircaloy-4 SEM microfractographies by using the fractal analysis technique. By reason of the current research, we introduce for the first time some new algorithms, most of them based on Box Counting methods and variations for 2D and 3D structures. The Box Counting algorithm is an efficient algorithm to compute the Fractal Dimension and can be applied directly on gray-levels images.
In accordance with ISO 4049/2000 Standard, the alleged radioopaque restorative materials must have a radioopacity value similar or higher with an aluminum layer of the same thickness. Depth polymerization of RDC represents half the depth of hardening under experimental conditions. European Standard requires a minimum of 0.5 mm for opaque diacrylic cements, 1 mm for opaque shades of restorative materials, respectively 1.5 mm for the other materials [11]. The aim of this study is to measure the radioopacity of different nanocomposite materials and coordinate this with the material’s performance.
The aim of our scanning electron microscopic study was to evaluate the cleaning efficiency of irrigating solutions used in endodontic treatment regarding smear layer removal from the root canal dentin walls. Ethylenediaminotetraacetic acid (EDTA)17%, citric acid(CA)10% and chlorohexidinegluconate (CHX)2% solutions were tested as final irrigants after endodontic treatment. The study was conducted on extracted teeth, divided in four groups according to the irrigation protocol used. The specimens were analyzed by scanning electron microscopy and the amount of smear layer present at apical, middle and coronal level was recorded, based on a scoring system. Data were statistically analyzed using Kruskal-Wallis and Friedman test and the level of significance was set at p[0.05. At the coronal and middle thirds we recorded no statistically significant difference between EDTA and CA regarding the smear layer removing capacity. Final irrigation with 10% CA proved to be more efficient than 17% EDTA in smear layer removal at apical level of the root canal, with p[0.05 (p=0.036), which is an important area for disinfection in endodontic treatment.
HY zeolite (solid acid) doped poly (aniline) has been synthesized through oxidative polymerization of aniline with ammouim peroxydisulfate used as an oxidant in aqueous medium. The influence of HY zeolite contents (5wt %, 10 wt %, 15wt %, 20wt % and 50 wt %) on the conductivity characteristic, thermal stability, and specific surface area of poly (aniline)/ HY zeolite composites was performed. All samples were characterized by FTIR, UV-Vis, XRD, TGA and SEM techniques. The electrical conductivity was measured using a four-probe method and it was found to be equal to 2.2 S/cm. FTIR spectra has confirmed the presence of poly (aniline) in the form of conducting emeraldine salt and suggest significant interaction of poly(aniline) with HY zeolite.