Ternary Chalcogenide-Based Quantum Dots and Carbon Nanotubes: Establishing a Toolbox for Controlled Formation of Nanocomposites.

A general procedure based on electrostatic self-assembly for preparing nanocomposites based on carbon nanotubes (CNTs) and ternary chalcogenide semiconductor nanoparticles is shown. This was achieved by surface functionalization of the single components through well-established protocols, for CNTs, and a transferable general strategy for the nanoparticles. Heterostructures were then synthesized through electrostatic interaction between oppositely charged components. Structural, colloidal, and optical properties were characterized by transmission electron microscopy, X-ray diffraction, infrared spectroscopy, dynamic light scattering, ζ-potential, and absorption- and (time-resolved) photoluminescence measurements. Interestingly, the nanocomposites showed a blue shift in their excitation and emission spectra when compared to the pure nanoparticles but only when analyzed in powder form. Further investigations in the form of density functional theory (DFT) calculations were performed to evaluate the origin of the change in the optical properties.

Decontamination of disposable respirators for reuse in a pandemic employing in-situ-generated peracetic acid.

BACKGROUND: During shortages of filtering face pieces (FFP) in a pandemic, it is necessary to implement a method for safe reuse or extended use. Our aim was to develop a simple, inexpensive and ecological method for decontamination of disposable FFPs that preserves filtration efficiency and material integrity. MATERIAL AND METHODS: Contamination of FFPs (3M Aura 9320+) with SARS-CoV-2 (1.15 × 104 PFUs), Enterococcus faecium (>106 CFUs), and physiological nasopharyngeal flora was performed prior to decontamination by submersion in a solution of 6 % acetic acid and 6 % hydrogen peroxide (6%AA/6%HP solution) over 30 minutes. Material integrity was assessed by testing the filtering efficiency, loss of fit and employing electron microscopy. RESULTS AND DISCUSSION: Decontamination with the 6%AA/6%HP solution resulted in the complete elimination of SARS-CoV-2, E. faecium and physiological nasopharyngeal flora. Material characterization post-treatment showed neither critical material degradation, loss of fit or reduction of filtration efficiency. Electron microscopy revealed no damage to the fibers, and the rubber bands' elasticity was not affected by the decontamination procedure. No concerning residuals of the decontamination procedure were found. CONCLUSION: The simple application and widespread availability of 6%AA/6%HP solution for decontaminating disposable FFPs make this solution globally viable, including developing and third world countries.

Cutaneous hyperpigmentation induced by doxycycline: histochemical and ultrastructural examination, laser microprobe mass analysis, and cathodoluminescence.

Skin hyperpigmentation induced by minocycline is a well-recognized side effect of minocycline but has rarely been reported for other tetracyclines. Based on a previously reported unusual case of chronic doxycycline abuse in a psychotic patient, we have investigated the nature of the observed pigment changes in the same patient. Histopathologic investigation of lesional skin by light microscopy disclosed hyperpigmentation of the basal keratinocytes and pigment-laden histiocytes in the dermis and subcutaneous fat. Only the pigment in the histiocytes of the upper dermis was reactive for Fontana Masson stain and could be bleached by hydrogen peroxide. The other histiocytes contained iron and calcium deposits as shown by von Kossa and Perls staining as well as by laser microprobe mass analysis. Ultrastructurally, these histiocytes contained amorphous material within the cytoplasm and stored in lysosomal structures. Comparative cathodoluminescence disclosed the presence of doxycycline in affected skin by means of overlapping emission spectra between the patient's skin and pure doxycycline. Taken together, the histomorphologic and ultrastructural changes induced by doxycycline shared several features with cutaneous hyperpigmentation caused by minocycline. Our biophysical findings further suggest a direct deposition of doxycycline, probably chelated with iron and/or calcium, within the lesional skin. Based on the presented unique case and the reviewed literature, only suprapharmacologic doses of doxycycline may be sufficient to cause such pigment changes.