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Chemical compounds, such as the CS gas employed in military operations, have a number of characteristics that impact the ecosystem by upsetting its natural balance. In this work, the toxicity limit and microorganism's reaction to the oxidative stress induced by O-chlorobenzylidenemalonitrile, a chemical found in CS gas, were assessed in relation to the green algae Chlorella pyrenoidosa. A number of parameters, including the cell growth curve, the percent inhibition in yield, the dry cell weight, the percentage viability and productivity of algal biomass flocculation activity, and the change in oxygen production, were analyzed in order to comprehend the toxicological mechanisms of O-chlorobenzylidenemalonitrile on algal culture. Using fluorescence and Fourier transform infrared spectroscopy (FTIR), the content of chlorophyll pigments was determined. The values obtained for pH during the adaptation period of the C. pyrenoidosa culture were between 6.0 and 6.8, O2 had values between 6.5 and 7.0 mg/L, and the conductivity was 165–210 µS/cm. For the 20 µg/mL O-chlorobenzylidenemalonitrile concentration, the cell viability percentage was over 97.4%, and for the 150 µg/mL O-chlorobenzylidenemalonitrile concentration was 74%. The ECb50 value for C. pyrenoidosa was determined from the slope of the calibration curve; it was estimated by extrapolation to the value of 298.24 µg/mL. With the help of this study, basic information on the toxicity of O-chlorobenzylidenemalonitrile to aquatic creatures will be available, which will serve as a foundation for evaluating the possible effects on aquatic ecosystems. The management of the decontamination of the impacted areas could take the results into consideration. [ABSTRACT FROM AUTHOR]

Abstract Magnetic nanoparticles were obtained using an adjusted Massart method and were covered in a layer-by-layer technique with hydrogel-type biocompatible shells, from chitosan and hyaluronic acid. The synthesized nanocomposites were characterized using dynamic light scattering, transmission electron microscopy, and Fourier transformed infrared spectroscopy. Biocompatibility of magnetic nanostructures was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) cell proliferation assay, swelling tests, and degradation tests. In addition, interaction of hydrogel-magnetic nanoparticles with microorganisms was studied. The possibility of precise nanoparticles size control, as long as the availability of bio-compatible covering, makes them suitable for biomedical applications.

In this paper, multi-walled carbon nanotubes have been prepared at low synthesis temperatures and without high pressure by a simple chemical route. Fourier transformed infrared spectroscopy, Raman spectroscopy and X-ray diffraction analysis was used to determine the purity of the synthetized compound. Also, by transmission electron microscopy and atomic force microscopy, a diameter between 9 nm and 43 nm and approximately 500–600 nm in length of multi-walled carbon nanotubes, was confirmed. Further, the multi-walled carbon nanotubes functionalized with negative charged functional groups (anionic groups) were decorated with hydroxyapatite by co-precipitation method. The decoration of multi-walled carbon nanotubes with hydroxyapatite was confirmed by transmission electron microscopy, Fourier transformed infrared spectroscopy and X-ray diffraction analysis. Also, energy-dispersive X-ray analysis proved the successfully obtaining of the nanocomposites. The simple method presented here may be extended to synthesize other composites based on coated multi-walled carbon nanotubes. [ABSTRACT FROM AUTHOR]

Four metal substituted hydroxyapatites (HAPs) were prepared and characterized using energy-dispersive X-ray fluorescence, X-ray diffraction, thermal analysis, and transmission electron microscopy. From the evaluation of the potential applications for antimicrobial properties and the photodegradation of methylene blue, it can be concluded that the two applications seem to be competing. Thus, Mn-substituted HAP, which provided the best degradation efficiency for methylene blue from the substituted materials (approximately 88%), has poor antimicrobial potential against most of the studied microbial lines. The Co-substituted HAP showed favorable antimicrobial properties against all the studied lines, including the lowest values for both minimum inhibitory concentration and a minimal concentration for biofilm eradication of 78.1 µg/mL against Pseudomonas aeruginosa, but exhibited a low degradation efficiency for methylene blue (approximately 42%). This can be explained by the properties of the pure material: pure HAP that showed the highest degradation efficiency of methylene blue (93%) but exhibited no antimicrobial efficiency against the studied lines. Thus, from the performed experiments, a single material cannot be recommended for both applications, but rather a specific material should be employed for each potential use: HAP, Mn- or Sn-substituted HAP for photodegradation, and Co-substituted HAP for antimicrobial applications. [ABSTRACT FROM AUTHOR]

In this paper we present the synthesis of bolaform gluconolactone-based surfactants with C8 and C12 hydrocarbon chains, in mild reaction conditions and the influence of hydrocarbon chain length on the surface properties of synthesized surfactants. The structural characterization of 1,12-digluconamidododecane and 1,8-digluconamidooctane was made by Fourier transform infrared spectroscopy. The visualization of aggregates was performed by optic microscopy in the case of 1,12-digluconamidododecane and transmission electron microscopy for 1,8- digluconamidooctane. It was found that 1,12-digluconamidododecane undergoes a crystallization process, hexagonal crystals being visualized by optic microscopy. We note the vesicular aggregates formed in the 1,8 - digluconamidooctane solution with dimensions between 200-300 nm, visualized by transmission electron microscopy. The surface activity of surfactants was evaluated with a KSV Sigma 700 automated tensiometer, using DuNouy Ring technique. 1,12-digluconamidododecane solutions present a moderate efficiency in reducing the surface tension of water, while 1,8- digluconamidooctane is more efficient in reducing the surface tension of water at low concentrations. [ABSTRACT FROM AUTHOR]

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