Electrochemical and Electrical Performances of High Energy Storage Polyaniline Electrode with Supercapattery Behavior.

Polyaniline (PANI), due to its highly reversible electrochemistry with superior energy storage and delivery characteristics, is considered as an electrode material in batteries, capacitors, and hybrid systems. We used a facile electrochemical synthesis for the formation of the PANI electrode using galvanostatic polymerization of aniline on the graphite electrode at the current density of 2.0 mA cm-2 from the aqueous electrolyte containing 0.25 mol dm-3 aniline and 1.0 mol dm-3 H2SO4. Electrochemical and electrical characterization suggested excellent energy storage features of the PANI electrode in a three-electrode system with specific energy up to 53 Wh kg-1 and specific power up to 7600 W kg-1. After 2000 successive charge/discharge cycles at 9.5 Ag-1, the PANI electrode retained 95% of the initial capacity, with practically unaltered Coulombic efficiency of nearly 98%, providing a good base for future studies and practical applications.

Nanoscale zerovalent iron (nZVI) supported by natural and acid-activated sepiolites: the effect of the nZVI/support ratio on the composite properties and Cd2+ adsorption.

Natural (SEP) and partially acid-activated (AAS) sepiolites were used to prepare composites with nanoscale zerovalent iron (nZVI) at different (SEP or AAS)/nZVI ratios in order to achieve the best nZVI dispersibility and the highest adsorption capacity for Cd2+. Despite the higher surface area and pore volume of AAS, better nZVI dispersibility was achieved by using SEP as the support. On the other hand, a lower oxidation degree was achieved during the synthesis using AAS. X-ray photoelectron spectroscopy (XPS) analysis of the composite with the best nZVI dispersibility, before and after Cd2+ adsorption, confirmed that the surface of the nZVI was composed of oxidized iron species. Metallic iron was not present on the surface, but it was detected in the subsurface region after sputtering. The content of zerovalent iron decreased after Cd2+ adsorption as a result of iron oxidation during Cd2+ adsorption. The XPS depth profile showed that cadmium was present not only at the surface of the composite but also in the subsurface region. The adsorption isotherms for Cd2+ confirmed that the presence of SEP and AAS decreased the agglomeration of the nZVI particles in comparison to the pure nZVI, which provided a higher adsorption capacity. The results showed that the prevention of both aggregation and oxidation during the synthesis was necessary for obtaining an SEP/AAS-nZVI composite with a high adsorption capacity, but oxidation during adsorption was beneficial for Cd2+ removal. The formation of strong bonds between Cd2+ and the adsorbents sites of different energy until monolayer formation was proposed according to modeling of the adsorption isotherms.

In vitro cell response to Co-containing 1,393 bioactive glass.

Cobalt ions are known to stimulate angiogenesis via inducing hypoxic conditions and hence are interesting agents to be used in conjunction with bioactive glasses (BGs) in bone tissue engineering approaches. In this work we investigated in vitro cell biocompatibility of Co releasing 1393 BG composition (in wt.%: 53SiO2, 6Na2O, 12K2O, 5MgO, 20CaO, and 4P2O5) derived scaffolds with osteoblast-like cells (MG-63) and human dermal microvascular endothelial cells (hDMECs). Cell viability, cell number and cell morphology of osteoblast-like cells in contact with particulate glass and 3D scaffolds were assessed showing good biocompatibility of 1393 reference material and with 1 wt.% CoO addition whereby 5 wt.% of CoO in the glass showed cytotoxicity. Furthermore for 1393 with 1 wt.% of CoO increased mitochondrial activity was measured. Similar observations were made with hDMECs: while 1393 and 1393 with 1 wt.% CoO were biocompatible and the endothelial phenotype was retained, 5 wt.% CoO containing BG showed cytotoxic effects after 1 week of cell culture. In conclusion, 1 wt.% Co containing BG was biocompatible with osteoblast like cells and endothelial cells and showed slightly stimulating effects on osteoblast-like cells whereas the addition of 5 wt.% CoO seems to exceed the vital therapeutic ranges of Co ions being released in physiological fluids.

Impregnation of cotton fabric with silver nanoparticles synthesized by dextran isolated from bacterial species Leuconostoc mesenteroides T3.

This study was aimed to highlight the possibility of cotton fabric impregnation with silver nanoparticles synthesized by dextran isolated from Leuconostoc mesenteroides T3 in order to obtain antimicrobial properties. The fabrication of dextran was proved by FTIR spectroscopy. Particle sizes of synthesized dextran and silver nanoparticles were measured by dynamic light scattering method. The presence of silver nanoparticles on the surface of cotton fabric was confirmed by scanning electron microscopy, X-ray diffraction measurements and reflectance spectrophotometry. Antimicrobial activity of cotton fabric impregnated with silver nanoparticles was tested against bacteria Escherichia coli and Staphylococcus aureus, and fungus Candida albicans. The results indicated that synthesized silver nanoparticles can provide satisfactory antimicrobial activity. However, maximum reduction (99.9%) of all tested microorganisms can be obtained only when 1.0mmolL(-1) colloid consisting of silver nanoparticles is applied.

Cobalt-releasing 1393 bioactive glass-derived scaffolds for bone tissue engineering applications.

Loading biomaterials with angiogenic therapeutics has emerged as a promising approach for developing superior biomaterials for engineering bone constructs. In this context, cobalt-releasing materials are of interest as Co is a known angiogenic agent. In this study, we report on cobalt-releasing three-dimensional (3D) scaffolds based on a silicate bioactive glass. Novel melt-derived "1393" glass (53 wt % SiO2, 6 wt % Na2O, 12 wt % K2O, 5 wt % MgO, 20 wt % CaO, and 4 wt % P2O5) with CoO substituted for CaO was fabricated and was used to produce a 3D porous scaffold by the foam replica technique. Glass structural and thermal properties as well as scaffold macrostructure, compressive strength, acellular bioactivity, and Co release in simulated body fluid (SBF) were investigated. In particular, detailed insights into the physicochemical reactions occurring at the scaffold-fluid interface were derived from advanced micro-particle-induced X-ray emission/Rutherford backscattering spectrometry analysis. CoO is shown to act in a concentration-dependent manner as both a network former and a network modifier. At a concentration of 5 wt % CoO, the glass transition point (Tg) of the glass was reduced because of the replacement of stronger Si-O bonds with Co-O bonds in the glass network. Compressive strengths of >2 MPa were measured for Co-containing 1393-derived scaffolds, which are comparable to values of human spongy bone. SBF studies showed that all glass scaffolds form a calcium phosphate (CaP) layer, and for 1393-1Co and 1393-5Co, CaP layers with incorporated traces of Co were observed. The highest Co concentrations of ∼12 ppm were released in SBF after reaction for 21 days, which are known to be within therapeutic ranges reported for Co(2+) ions.

The influence of different radiopacifying agents on the radiopacity, compressive strength, setting time, and porosity of Portland cement.

OBJECTIVES: The aims of this study were to evaluate the radiopacity, compressive strength, setting time, and porosity of white Portland cement (PC) with the addition of bismuth oxide (Bi2O3), zirconium dioxide (ZrO2), and ytterbium trifluoride (YbF3) after immersion at 37 °C for 7 days in distilled water or phosphate buffer saline. MATERIALS AND METHODS: Specimens measuring 8 mm in diameter and 1 mm in thickness were fabricated from PC with the addition of 10, 20, and 30 wt% Bi2O3, ZrO2 or YbF3. ProRoot MTA (Dentsply, Tulsa, OK, USA) and pure PC were used as controls. For radiopacity assessments, specimens were radiographed alongside a tooth slices and an aluminum stepwedge on Extraspeed occlusal dental films (Insight Kodak, Rochester, New York). Mean optical density of each specimen was calculated and used to express radiopacity of the material as an equivalent thickness of aluminum. Compressive strength was measured by using 4-mm diameter and 6-mm high specimens and Universal testing machine. High-pressure mercury intrusion porosimeter (Carlo Erba Porosimeter 2000) was employed to measure the porosity of the specimens. The setting time was measured by using a needle of 100 g in weight. The morphology of specimens was evaluated using a scanning electron microscope (TESCAN Mira3 XMU, USA Inc.). Data were analyzed by one-way ANOVA and post hoc Tukey test (P < 0.05). RESULTS: The PC with the addition of at least 10 wt% Bi2O3 and 20 wt% ZrO2 or YbF3 demonstrated greater radiopacity value than the recommended 3 mmAl cut-off. ZrO2 and YbF3 increased the compressive strength of PC, but it was not statistically significant (P > 0.05), while Bi2O3 decreased it (P < 0.05). All radiopacifiers significantly increased the porosity of the experimental cements (P < 0.05). Bi2O3 extended the setting time of PC (P < 0.05), whilst ZrO2 and YbF3 did not significantly affect it (P > 0.05). CONCLUSIONS: ZrO2 and YbF3 may be used as a suitable alternative to replace Bi2O3 in MTA without influencing its physical properties.

Effect of hydroxyapatite spheres, whiskers, and nanoparticles on mechanical properties of a model BisGMA/TEGDMA composite initially and after storage.

This study investigated the effect of shape, size, and surface modification of hydroxyapatite (HAP) fillers on the degree of conversion (DC) and mechanical properties of a model BisGMA/TEGDMA composite initially and after 4 weeks of storage. Ten percent of conventional glass fillers were replaced by HAP spheres (Sph), silicon-doped spheres (SphSi), whiskers (Wh), silicon-doped whiskers (WhSi), and nanosized HAP particles (Nano). Spheres were specifically structured agglomerates consisting of a central void and radially orientated primary particles, whereas whiskers were compact monocrystals. DC, Vickers hardness (HV), flexural strength (Fs), flexural modulus (Ef), compressive strength (Cs), and compressive modulus (Ec) were tested. There were no significant differences in the DC between all tested groups. HV decreased by 5.4-17% with the addition of HAP, while Fs increased by 13.9-29% except in Nano group (decrease by 13%). After storage, Sph and SphSi groups showed similar HV, Ef, Cs and Ec and higher Fs than the control. The fracture mode of HAP spheres was through the central void whereas whiskers showed longitudinal delamination, transverse, and mixed fractures. HAP spheres with or without silicon- doping have a potential to be part of the filler content of dental composites.

Lactic acid production on liquid distillery stillage by Lactobacillus rhamnosus immobilized onto zeolite.

In this study, lactic acid and biomass production on liquid distillery stillage from bioethanol production with Lactobacillus rhamnosus ATCC 7469 was studied. The cells were immobilized onto zeolite, a microporous aluminosilicate mineral and the lactic acid production with free and immobilized cells was compared. The immobilization allowed simple cell separation from the fermentation media and their reuse in repeated batch cycles. A number of viable cells of over 10(10) CFU g(-1) of zeolite was achieved at the end of fourth fermentation cycle. A maximal process productivity of 1.69 g L(-1), maximal lactic acid concentration of 42.19 g L(-1) and average yield coefficient of 0.96 g g(-1) were achieved in repeated batch fermentation on the liquid stillage without mineral or nitrogen supplementation.

[Accuracy of optical scanning methods of the Cerec 3D system in the process of making ceramic inlays].

BACKGROUND/AIM: One of the results of many years of Cerec 3D CAD/CAM system technological development is implementation of one intraoral and two extraoral optical scanning methods which, depending on the current indications, are applied in making fixed restorations. The aim of this study was to determine the degree of precision of optical scanning methods by the use of the Cerec 3D CAD/CAM system in the process of making ceramic inlays. METHODS: The study was conducted in three experimental groups of inlays prepared using the procedure of three methods of scanning Cerec 3D system. Ceramic inlays made by conventional methodology were the control group. The accuracy of optical scanning methods of the Cerec 3D system computer aided design-computer aided manufacturing (CAD/CAM) was indirectly examined by measuring a marginal gap size between inlays and demarcation preparation by scanning electron microscope (SEM). RESULTS: The results of the study showed a difference in the accuracy of the existing methods of scanning dental CAD/CAM systems. The highest level of accuracy was achieved by the extraoral optical superficial scanning technique. The value of marginal gap size inlays made with the technique of extraoral optical superficial scanning was 32.97 +/- 13.17 mus. Techniques of intraoral optical superficial and extraoral point laser scanning showed a lower level of accuracy (40.29 +/- 21.46 mus for inlays of intraoral optical superficial scanning and 99.67 +/- 37.25 mus for inlays of extraoral point laser scanning). CONCLUSION: Optical scanning methods in dental CAM/CAM technologies are precise methods of digitizing the spatial models; application of extraoral optical scanning methods provides the highest precision.