Comparative physicochemical analysis of galvanic sludge wastes.

The paper provides the physicochemical analysis of galvanic sludge to determine the presence and concentration of toxic metals. Two sludges sampled from the same factory, but from different technological processes, alkaline galvanic sludge obtained from galvanizing process and acidic sludge generated from the chromium plating process were analyzed. Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES) revealed increased concentrations of toxic heavy metal ions Zn2+, Cr3+, Ni2+ and Pb2+ in the sludge from the galvanizing process and Cr3+, Cu2+, Ni2+, Pb2+, Cd2+ and Zn2+ from the chroming process. Moreover, the sludges were further physicochemically characterized by Reflectance Fourier Transform InfraRed Spectrometry (FTIR), Scanning Electron Microscopy with Energy-dispersive X-ray Spectroscopy Analysis (SEM-EDX) and X-ray diffraction (XRD). The results of ICP-OES were corroborated by FTIR. Analysis of FTIR spectra revealed the specific bands indicating the existence of metal oxides in the analyzed sludges, as well as the presence of organic substances, i.e. solvents and surfactants, used in the electroplating process. The analysis was accomplished following international norms and confirmed the increased concentrations of heavy metal ions from both sludges. In line with the regulations of the Environmental Protection Agency (EPA), the results proved the hypothesis that galvanic sludge is hazardous waste.

Structure and dynamics of nucleic acids.

In this chapter we describe the application of CW and pulsed EPR methods for the investigation of structural and dynamical properties of RNA and DNA molecules and their interaction with small molecules and proteins. Special emphasis will be given to recent applications of dipolar spectroscopy on nucleic acids.

Design and preparation of proline, tryptophan and poly-l-lysine functionalized magnetic nanoparticles and their radiolabeling with 131I and 177Lu for potential theranostic use.

Surface modification of magnetic nanoparticles with poly-l-lysine, proline, and tryptophan was used to design potential theranostic agents for the application in cancer diagnosis and radionuclide-hyperthermia therapy. Characterization of bare and functionalized magnetic nanoparticles was performed in detail. The transparency of the examined magnetic nanoparticles was measured in the non-alternating magnetic field for a complete and better understanding of hyperthermia. For the first time amino acid-functionalized magnetic nanoparticles were labeled with theranostic radionuclides 131I and 177Lu. The specific absorption rate (SAR) procured for poly-l-lysine functionalized magnetic nanoparticles (SAR values of 99.7 W/g at H0 = 15.9 kA/m and resonant frequency of 252 kHz) demonstrated their possible application in magnetic hyperthermia. Poly-l-lysine functionalized magnetic nanoparticles labeled with 177Lu showed the highest radiochemical purity (>99.00 %) and in vitro stability in saline and serum (>98.00 % up to 96 h). The in vivo analysis performed after their intravenous administration in healthy Wistar rats presented good in vivo stability for several days. Encouraging results as well as magnetic and radiochemical properties of 177Lu-PLL-MNPs (80 °C) justify their further testing toward the potential use as theranostic agents for diagnostic and combined radionuclide-hyperthermia therapeutic applications.

Photoinduced formation of reversible dye radicals and their impact on super-resolution imaging.

Radical ions of organic dyes are highly reactive species and have been studied for decades by transient absorption spectroscopy and pulse radiolysis experiments in oxygen-depleted solution. Here we show by continuous wave EPR, absorption, and fluorescence experiments that the triplet state of rhodamine dyes can be photoreduced by thiols to form stable radical anions in aqueous solution with a lifetime of up to several hours. Our data demonstrate that reduction of the triplet state and photoinduced oxidation of reactive intermediates by oxygen represents a general mechanism for reversible photoswitching of dyes in aqueous thiol-containing solutions highlighting the key role of molecular oxygen for super-resolution fluorescence imaging. Since cells contain the thiol glutathione at millimolar concentrations and reactive oxygen species are formed as side products our findings are of consequence for live cell fluorescence microscopy.

PELDOR spectroscopy reveals preorganization of the neomycin-responsive riboswitch tertiary structure.

Pulsed electron double resonance (PELDOR) spectroscopy reveals a prearranged tertiary structure of the 27 nucleotides long engineered neomycin-responsive riboswitch. Measured distances between spin labels at positions U4-U14, U4-U15, U14-U26, and U15-U26 were unchanged upon neomycin binding which implies that the global stem-loop architecture is preserved in the absence and presence of the ligand. On the basis of our results, we infer that low-temperature PELDOR data unambiguously demonstrate the existence of an enthalpically favorable set of RNA conformations ready to bind the ligand without major global rearrangement.