română VIRGIL PENTA, CAMELIA UNGUREANU, ANDREI BOGDAN STOIAN, CRISTIAN PIRVU
Abstract
Candida albicans is the most frequently isolated pathogen yeast and is present in the oral cavity of almost half of the population. Since there have been several seemingly contradictory studies on the effect of electricity on C. albicans behavior, we propose a new method of measurement: Electrochemical Impedance Spectroscopy (EIS) coupled with Surface Plasmon Resonance (SPR). Along with other electrochemical methods and high-resolution Atomic Force Microscopy (AFM) imagery we investigated the effect of electric potentials measured between metallic intraoral restorations materials on C. albicans.
Keywords
Candida albicans, biofilm, Surface Plasmon Resonance, Electrochemical Impedance Spectroscopy, Atomic Force Microscopy
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Year
2022
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Issue
52 (2)
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Pages
145-155
VIOLETA TSAKIRIS, DORINEL TĂLPEANU , MAGDALENA VALENTINA LUNGU, DELIA PĂTROI, GABRIELA BEATRICE SBÂRCEA, VIRGIL EMANUEL MARINESCU
Abstract
For the replacement and regeneration of hard and damaged tissues, it is preferable to use orthopedic implants from Mg-based biomaterials. It is desirable that orthopedic implants have mechanical properties similar to those of natural bone to avoid the effect of stresses due to the difference in properties of materials, i.e. between bone and implant. Numerous studies have shown that of all metallic biomaterials, Mg used as an orthopedic biomaterial can promote bone reconstruction and accelerate the healing process, having both density and modulus of elasticity close to cortical bone.
In this paper, Mg-Zn-(Mn) biomaterials with 5 wt.% Zn and/without a small addition of Mn (0.3 wt.%) were synthesized by high-energy mechanical milling of the component powders mixtures and consolidated by Spark Plasma Sintering technique, at different sintering temperatures (350, 400 and 450°C) to be used as orthopedic implants. The influence of the mechanical milling and sintering parameters, on the chemical, structural and physical characteristics was investigated. Properties suitable for the intended application, in terms of physical properties such as density 1.77-1.78 g/cm3, hardness (95-112 HV), and Young Modulus (36-46 GPa) recommend the alloys obtained from Mg-Zn-(Mn), as potential biomaterials. These biomaterials resulted from the composite powder mechanical milled for 5 h and sintered at the highest sintering temperature (450°C).
Keywords
doped magnesium, biomaterial, SPS technique, osseous implants
NAZMI EKREN, CEYLIN EDA KARACAN
Abstract
Electrospun patches have attracted interest in different biomedical fields, including tissue engineering and drug delivery. Portable electrospinning guns promise faster and more practical interventions in these areas. In this article, the design, construction and testing of a portable electrospinning gun are described to produce fiber and particle products. Results were discussed depending on the electrospinning gun’s working system and properties of the products. The electrospinning gun system could have a high voltage of up to 30 kV. Also, no heating problems were encountered during high voltage values. Due to the uniformity, reproducibility and tunability of the produced PCL and PMSQ fibers, it can be said that electrospinning gun can be used in nanotechnology, drug delivery systems and wound dressing applications.
Keywords
Electrospinning, electrospinning gun, fiber, wound dressing, biomedical
I. GOMOIU , M. ENACHE, S. NEAGU , R. RUGINESCU, M. DUMBRĂVICIAN, R. RADVAN, L. GHERVASE, I. MOHANU, R. COJOC
Abstract
Biological cleaning of the restored of artworks is a green methodology which avoids the toxicity of solvents used in dry cleaning and protects restorers and environment. Biocleaning with viable bacteria cultures has been used successfully to remove black crust, mineral salts deposits, and organic matter residues, due to selective and specific metabolites proving to be more effective than chemical methods. Biocleaning treatments were applied for removing of the organic materials used in previous restoration or accidentally filed onto an artwork. Gels captured the attention of restorers and their applicability quickly extended to murals, stone, paper, even metals. Agarart hydrogel is recommended both for cleaning of artworks and as a delivery system. This study aimed to remove consolidants (acrylic resin Paraloid B72, Transparent Dispersion of Casein) and accidental organic deposits (beewax, sunflower oil and soot) from the surface of the murals with esterolytic enzymes produced by halotolerant bacteria Bacillus sp. BA N P3.3, applied directly or integrated in Agarart. The experiments were carried out on laboratory models aged by exposure to variations of temperature and humidity respectively to UV-A/UV-B radiation. Although biocleaning was achieved by applying of the esterolytic enzymes entrapped in Agarart gel (E-Agarart) or directly on the surface of organic deposit and then covered with Agarart gel (E+Agarart), to avoid the development of efflorescences, treatment with esterolytic enzymes integrated in Agarart gel is recommended.
Keywords
halotolerant and halophilic microorganisms, biotechnologies for conservation and restoration, hydrolytic enzymes, integrated esterase in hidrogels, biocleaning with fungal cultures
SATISHKUMAR SENGOTTAIYAN, SURESH PARAMASIVAM
Abstract
The health risks connected with the use of asbestos-based brake linings have sparked research into the use of environmentally benign agro-based biomaterials as reinforcing agents in composite materials used in the manufacturing of brake pad linings. The purpose of this research is to determine the feasibility of employing coconut shell (CS) powder in the manufacturing of asbestos-free brake lining materials. The powders, in conjunction with the appropriate fillers, were utilised in the manufacture of the brake lining. The compositions of the reinforcing powders were varied between 20% and 35%, those of the resin binder were varied between 58 and 43%, and those of the filler metal and curing agents were maintained constant. Weighed, prepared, mixed, cured, and moulded these materials. Water and oil absorption, compressive strength, hardness, and wear tests were performed on the created composite materials. The research indicated that increasing the amount of reinforcing elements leads in an increase in the samples water and oil absorption. Compressive strength of the composite rose proportionately with the addition of up to 35% composition. The coefficient of friction tested was determined to be within an acceptable range. Additionally, when combined with other fillers and confined, CS powder shown great potential for brake lining manufacturing.
Keywords
Coconut shell (CS), Brake linings, Compressive strength, Hardness, wear
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Year
2022
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Issue
52 (4)
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Pages
368-373