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Here, we present the results of the synthesis, surface modification, and properties analysis of magnetite-based nanoparticles, specifically Co0.047Fe2.953O4 (S1) and Co0.086Fe2.914O4 (S2). These nanoparticles were synthesized using the co-precipitation method at 80 °C for 2 h. They exhibit a single-phase nature and crystallize in a spinel-type structure (space group Fd 3 ¯ m). Transmission electron microscopy analysis reveals that the particles are quasi-spherical in shape and approximately 11 nm in size. An observed increase in saturation magnetization, coercivity, remanence, and blocking temperature in S2 compared to S1 can be attributed to an increase in magnetocrystalline anisotropy due to the incorporation of Co ions in the crystal lattice of the parent compound (Fe3O4). The heating efficiency of the samples was determined by fitting the Box-Lucas equation to the acquired temperature curves. The calculated Specific Loss Power (SLP) values were 46 W/g and 23 W/g (under HAC = 200 Oe and f = 252 kHz) for S1 and S2, respectively. Additionally, sample S1 was coated with citric acid (Co0.047Fe2.953O4@CA) and poly(acrylic acid) (Co0.047Fe2.953O4@PAA) to obtain stable colloids for further tests for magnetic hyperthermia applications in cancer therapy. Fits of the Box-Lucas equation provided SLP values of 21 W/g and 34 W/g for CA- and PAA-coated samples, respectively. On the other hand, X-ray photoelectron spectroscopy analysis points to the catalytically active centers Fe2+/Fe3+ and Co2+/Co3+ on the particle surface, suggesting possible applications of the samples as heterogeneous self-heating catalysts in advanced oxidation processes under an AC magnetic field. [ABSTRACT FROM AUTHOR]

Alkaline saline ponds and lakes are habitats with unique biodiversity. The green alga of the genus Botryococcus was accidentally discovered during a micro-algal survey of these habitats in Serbia. Species B. terribilis was found and identified for the first time in Serbia in the small sandpit lake of the Rusanda Nature Park. The first sampling was incomplete due to the unknown origin of the orange-red surface scum. After the identity of the species had been confirmed, three additional samplings were conducted aiming to collect phytoplankton and water samples for physical and chemical analyses. Major anions and cations were analysed in order to characterize the chemical type of sandpit lake, as well as nutrient content. Sandpit lake is an alkaline water body that belongs to sodium bicarbonate chemical type. Morphometric analysis of B. terribilis was performed using light and transmission electron microscopy. B. terribilis was found to be numerous in the phytoplankton community in late autumn and winter. Species from the genus Botryococcus are known as a rich source of different lipids and this discovery can be the first step in the further biotechnological application of this species in sustainable biofuel production.

Raw jute fabric was chemically modified with 1 % NaOH for 30 min, 17.5 % NaOH for 5 min or with 0.7 % NaClO2 for 30 and 60 min to study the influence of changes in the chemical composition of the fabrics and quantity of carboxyl groups on the biosorption capacity of the fabrics for nickel ions. The effects of contact time and initial concentration of nickel ions on the biosorption capacity of the fabrics were also investigated. The obtained results revealed that the biosorption of nickel ions can be explained by the pseudo-second- order kinetic model, while the experimental isotherm data fit better with the Langmuir model. The calculated ratios between maximal biosorption capacity (6.30–12.06 mg g-1) of the jute fabrics and carboxyl group quantity indicated that approximately half of the carboxyl groups of the fabrics’ would be involved in binding nickel ions during biosorption. Therefore, the quantity of carboxyl groups can be used to predict the maximal biosorption capacity of jute fabrics toward nickel ions. In the case of oxidized jute fabrics, the lignin removal, and consequently increased content of cellulose and hemicelluloses, also contributed to a higher biosorption capacity.

Due to the similar chemical properties of Ni2+ and Co2+, several dozens of adsorptive stripping voltammetric (AdSV) methods have been developed for their simultaneous determination. The question was would there be some benefits if a stripping method made for simultaneous determination of Ni2+ and Co2+ will be optimized for the determination of only one of them (Ni2+). It was found that the optimized method has for an order of magnitude lower LOQ (1.89×10−10 M), an order of magnitude lower influence of Co2+, and the applicability of one calibration line for four orders of magnitude of Ni2+ concentration. The influence of some common anions and cations has been examined. The developed method was successfully applied for nickel content determination in real samples. The suitability of the developed method for the determination of Co2+ from the same solution in the second run, upon optimizations of deposition potential and time, was also explored. The LOQ obtained for Co2+ (3.61×10−11 M) is almost two orders of magnitude lower than LOQ of the method for simultaneous determination of both cations and, its LOD and LOQ are among few lowest obtained by AdSV methods for Co2+ determination. The developed method for Ni2+ and Co2+ determination from the same solution in two successive runs has significantly better analytical performances than the starting method for their simultaneous determination in one run. [ABSTRACT FROM AUTHOR]

Background/Aim. The main task of endodontic treatment is to eliminate pathologically altered tissue, to disinfect root canal space and to obtain its three-dimensional hermetic obturation. The main purpose of this study was to evaluate antimicrobial activity of new endodontic nano-structured highly active calcium silicates based materials albo-mineral plyoxide carbonate aggregate (ALBO-MPCA) and calcium silicates (CS) in comparison to mineral trioxide aggregate (MTA+) and UltraCal XS (CH). Methods. The antimicrobial activity of materials was tested against Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 14506) strains, and following clinical isolates: Rothia dentocariosa, Enterococcus faecalis, Staphylococcus aureus, Streptococcus anginosus and Streptococcus vestibularis using a double layer agar diffusion test. The pH measurements were performed using the pH meter. Total amount of released ions was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Results. All tested materials showed the best antibacterial potential after 1 h of incubation. After 3h and 24h of the incubation period, the antibacterial potential of all tested materials were similar. The Agar diffusion test showed that ALBO-MPCA, CS and MTA+ had similar inhibition zones (p > 0.05), except in the activity against Staphylococcus aureus where ALBO-MPCA showed better antimicrobial properties than MTA+ in 3h and 24h of the incubation period (p < 0.05). Following 24h of the incubation, the inhibition zones were the strongest with CH against Staphylococcus aureus (16.67 ± 2.34 mm) followed by ALBO-MPCA (14.67 ± 1.21 mm) and the weakest with CS against Enterococcus faecalis (6.50 ± 1.76 mm). CH showed the highest pH, followed by ALBO-MPCA, CS and MTA+. Conclusion. The expressed antibacterial effects indicate that materials based on nano-structured highly active calcium silicates represent effective therapeutic agents for root canal obturation in one-visit apexification treatment, therefore they are recommend for further examination and clinical trials as they are proposed for MTA substitution. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172026 Grant no. TR31079]

The biological quality and chemical composition of alloys used in dental practice change during heat treatment. Often the residues of the previous cast are not disposed of but are reused and recycled until consumed. Thus, manufactured dental restorations have modified biological quality and chemical composition, and compromised biocompatibility. The aim of this study was to investigate the influence of repeated casting on the cytotoxicity of the silver-palladium (Ag-Pd) alloy. Our results showed that repeated casting of the Ag-Pd dental alloy affected its biocompatibility by promoting toxicity against transformed fibroblasts in a contact-independent manner. A strong decrease in cell proliferation, induction of senescence and massive cell death were observed in cultures exposed only to a medium previously incubated with dental alloy samples. The obtained data indicated that toxicity mediated by the accumulation of the Ag, Pd, Cu and Zn cations released from the Ag-Pd material was enhanced by recasting. The induction of cell senescence and subsequent apoptotic and necrotic death were accompanied by amplified intracellular production of reactive oxygen and nitrogen species, suggesting their involvement in the cell destruction process. Therefore, compromised biocompatibility after recasting with the Ag-Pd alloy can be the cause of serious local cell destruction, as observed in clinical practice. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45012 and Grant no. 173013]