Elidio Angioletto

The influence of particle size and AgNO3 concentration in the ionic exchange process on the fungicidal action of antimicrobial glass.

Antimicrobial materials have long been used as an effective means of reducing the risks posed to humans by fungi, bacteria and other microorganisms. These materials are essential in environments where cleanliness, comfort and hygiene are the predominate concerns. This work presents preliminary results for the development of a fungicidal vitreous material that is produced by the incorporation of a silver ionic specimen through ionic exchange reactions. Silver ions were incorporated into powdered glass via ionic exchange in an ionic medium containing silver species with different concentrations of AgNO3. The fungicidal efficiency of the samples was studied as a function of the AgNO3 concentration and the particle size of the glass using the agar diffusion test for the microbiological analysis of the fungus species Candida albicans. The samples were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The experimental results showed that the fungicidal effect was dependent on the AgNO3 concentration in the ionic exchange medium but was not dependent on the particle size of the glass.

Evaluation of the healing activity of therapeutic clay in rat skin wounds

The use of clays for therapeutic practice is widespread in almost all regions of the world. In this study the physicochemical and microbiological healing characteristics of a clay from Ocara, Brazil, popularly used for therapeutic uses, were analyzed. The presence of Ca, Mg, Al, Fe, and Si was observed, which initially indicated that the clay had potential for therapeutic use. The average particle size of the clay (26.3 μm) can induce the microcirculation of the skin and the XRD analysis shows that the clay is formed by kaolinite and illite, a swelling clay. During the microbiological evaluation there was the need to sterilize the clay for later incorporation into the pharmaceutical formula. The accelerated stability test at 50°C for 3 months has showed that the pharmaceutical formula remained stable with a shelf life of two years. After the stability test the wound-healing capacity of the formulation in rats was evaluated. It was observed that the treatment made with the formulation containing the Ocara clay showed the best results since the formula allowed greater formation of collagen fibers and consequent regeneration of the deep dermis after seven days of treatment and reepithelialization and continuous formation of granulation tissue at the 14th day.

Mechanical and toxicological evaluation of concrete artifacts containing waste foundry sand

The creation of metal parts via casting uses molds that are generally made from sand and phenolic resin. The waste generated after the casting process is called waste foundry sand (WFS). Depending on the mold composition and the casting process, WFS can contain substances that prevent its direct emission to the environment. In Brazil, this waste is classified according to the Standard ABNT NBR 10004:2004 as a waste Class II (Non-Inert). The recycling of this waste is limited because its characteristics change significantly after use. Although the use (or reuse) of this byproduct in civil construction is a technically feasible alternative, its effects must be evaluated, especially from mechanical and environmental points of view. Thus, the objective of this study is to investigate the effect of the use of WFS in the manufacture of cement artifacts, such as masonry blocks for walls, structural masonry blocks, and paving blocks. Blocks containing different concentrations of WFS (up to 75% by weight) were produced and evaluated using compressive strength tests (35 MPa at 28 days) and toxicity tests on Daphnia magna, Allium cepa (onion root), and Eisenia foetida (earthworm). The results showed that there was not a considerable reduction in the compressive strength, with values of 35 ± 2 MPa at 28 days. The toxicity study with the material obtained from leaching did not significantly interfere with the development of D. magna and E. foetida, but the growth of the A. cepa species was reduced. The study showed that the use of this waste in the production of concrete blocks is feasible from both mechanical and environmental points of view.

Effect of the Temperature in the Antimicrobial Action of the Bactericide Wood Polymer Composite - BWPC

These work present studies about influence of the high temperature at the antimicrobial properties of the Bactericide Wood Polymer Composites (BWPC) after exposition during different times at 110 oC. The composite was formulated containing Polypropylene (PP) as matrix polymeric, wood powder of the species Pinus and Triclosan additive as bactericide agent. The BWPC was exposited during different times in the ambient and submitted to microbiological tests. The Agar Diffusion tests were applied with two kind bacteria, the Echerichia coli (EC - Gram Positive) and Staphylococcus aureos (SA - Gram Negative). The FT-IR and TGA techniques were utilized to available of the temperature effect in the chemical structure of the composites BWPC. The studies showed a strong dependence of the bactericide action of the composites with exposition time at 110 oC and a constant bactericide action after 100 hours of exposition.

Bactericide Effect of Powder Glasses Submitted to Na+/Ag+ Ionic Exchange in Ionic Media Containing Different Concentration of AgNO3

This work presents preliminary results of powder glasses with bactericide effect obtained by ionic exchange between sodium ions, present in glass composition, and silver ions, present in the ionic exchange medium. The powder glass was submitted to ionic exchange in ionic medium containing different concentration of silver species. The results showed a bactericide effect dependence on AgNO3 concentration in the ionic medium. Agar Diffusion Test on Escherichia coli bacteria, EDS analyses was applied to the samples; the results showed there is a critical concentration of silver ions incorporated in the powder glass and a limit to bactericide effect. The tests and analyses reveled that 6 wt% of AgNO3 in ionic medium was the critical concentration.

Effect of the Extrusion Process on the Bactericidal Performance of Biocidal Polypropylene Catheters

This work concerns polypropylene biocidal catheters that incorporate the triclosan molecule. Many studies have applied triclosan as a bactericidal agent in the polymeric matrix but without considering the effect of processing on the biocidal properties. Using the optimal temperature and shear rate during the extrusion process can promote the best microbiological response for a biocidal catheter. Catheters were processed using a linear extruder while systematically varying the triclosan content, processing temperature and screw velocity. A diffusion test in agar and an evaluation of the chemical structure of the polypropylene and triclosan using FTIR were used to characterize the bactericidal properties.

Extrusion Effects with Bactericidal Additives in Polymer Wood Composites

Abstract Wood polymer composite is an important material class for industries. Microbiological properties can be an important aspect to enlarge its application base. The biocidal properties of wood polymer composite (WPC) can be aggregated by incorporation of biocidal additives on its composition. But, an important aspect is the evaluation the influence of the fabrication process on its biocidal properties. In particular, the temperature and screw velocity are important parameters for extrusion processes, and the mass proportions of the compounds are important factors to define the WPC properties. Different combinations of process conditions and mass proportions of the composite can promote variation in the magnitude of the bactericidal effect. The bactericidal properties are aggregated in the composite by organic bactericidal additive and the high temperature and high shear rate during the extrusion process can affect the effectiveness of the bactericidal additive function. This paper investigates the effects of the extrusion process parameters associated with different percentages of bactericidal additives on the WPC. The results showed significant effects on the bactericidal properties that depended only on the bactericidal content.

Porous Ceramic Structures Obtained from Calcium Carbonate as Pore Generating Agent

The aim of this work is to present experimental results related to the use of calcium carbonate as pore generating agent. Four compositions containing 20 wt.% of limestone were used and characterized chemically and thermally. Each composition was homogenized in a porcelain ball mill, dried in a laboratory drier, humidified at 7 wt.%, and pressed in an uniaxial hydraulic press. Compacted samples were dried and heat treated with a suitable heating rate for the degasification of calcium carbonate and sintered at 800, 900, and 1050 °C. Sintered samples were characterized to determine the porosity, crystalline phases formed and microstructural features. The results showed that the porosity has increased with the sintering temperature of the compositions increasing due porosity generated by the calcium carbonate degasification and the material expansion.

Study of Adsorption Kinetics of Heavy Metals in Acid Drainage from Coal Mining in Type A Zeolites

The present work studied the adsorption of ions of iron and manganese of the effluent from coal acid mine drainage (AMD), located in South of the Santa Catarina using for this purpose type 4A zeolite. Were tested the Langmuir adsorption isothermal model. Tests of adsorption of heavy metals were performed by varying the adsorption time and the ratio of the volume of effluent and the amount of adsorbent. The results showed the efficiency of kinetic adsorption of iron and manganese ions by the zeolite.

Influence of High Energy Milling on the Airflow Sensorproperty of the NBCa Ceramic

Some materials have been applied in many surrounding conditions as sensors, electronic devices and other applications. Inexpensive and reliable temperature and flow measurement are important in many applications including, for example, environmental monitoring and control, indoor air conditioning, weather forecasting, automotive and aerospace systems. Special ceramics are an example of such materials. Neodymium-Barium-Copper is a special ceramic that has high electrical conductivity and airflow sensor characteristics. This property is influenced by high energy milling of the powder, when it is not sintered. To evaluate the influence of this type of milling it was carried out an analysis of particle size as a function of milling time. SEM images and granulometric analysis showed significant reduction of particle size with the increase of milling time. For longer times of milling the mixture of precursor powders is favored, resulting in better homogeneity of the ceramic. This is reflected in the properties of airflow sensor.