Nanostructured Glass-Ceramic Materials from Glass Waste with Antimicrobial Activity.

Modern consumption patterns have led to a surge in waste glass accumulating in municipal landfills, contributing to environmental pollution, especially in countries that do not have well-established recycling standards. While glass itself is 100% recyclable, the logistics and handling involved present significant challenges. Flint and amber-colored glass, often found in high quantities in municipal waste, can serve as valuable sources of raw materials. We propose an affordable route that requires just a thermal treatment of glass waste to obtain glass-based antimicrobial materials. The thermal treatment induces crystallized nanoregions, which are the primary factor responsible for the bactericidal effect of waste glass. As a result, coarse particles of flint waste glass that undergo thermal treatment at 720 °C show superior antimicrobial activity than amber waste glass. Glass-ceramic materials from flint waste glass, obtained by thermal treatment at 720 °C during 2 h, show antimicrobial activity against Escherichia coli after just 30 min of contact time. Laser-induced breakdown spectroscopy (LIBS) was employed to monitor the elemental composition of the glass waste. The obtained glass-ceramic material was structurally characterized by transmission electron microscopy, enabling the confirmation of the presence of nanocrystals embedded within the glass matrix.

Optimizing Josephson Junction Reproducibility in 30 kV E-Beam Lithography: An Analysis of Backscattered Electron Distribution.

This paper explores methods to enhance the reproducibility of Josephson junctions, which are crucial elements in superconducting quantum technologies, when employing the Dolan technique in 30 kV e-beam processes. The study explores the influence of dose distribution along the bridge area on reproducibility, addressing challenges related to fabrication sensitivity. Experimental methods include e-beam lithography, with electron trajectory simulations shedding light on the behavior of backscattered electrons. Wedescribe the fabrication of various Josephson junction geometries and analyze the correlation between the success rates of different lithography patterns and the simulated distribution of backscattered electrons. Our findings demonstrate a success rate of up to 96.3% for the double-resist 1-step low-energy e-beam lithography process. As a means of implementation strategy, we provide a geometric example that takes advantage of simulated stability regions to administer a controlled, uniform dose across the junction area, introducing novel features to overcome the difficulties associated with fabricating bridge-like structures.

Therapeutic potential of low-cost nanocarriers produced by green synthesis: macrophage uptake of superparamagnetic iron oxide nanoparticles.

Aim: The primary goal of this work was to synthesize low-cost superparamagnetic iron oxide nanoparticles (SPIONs) with the aid of coconut water and evaluate the ability of macrophages to internalize them. Our motivation was to determine potential therapeutic applications in drug-delivery systems associated with magnetic hyperthermia. Materials & methods: We used the following characterization techniques: x-ray and electron diffractions, electron microscopy, spectrometry and magnetometry. Results: The synthesized SPIONs, roughly 4 nm in diameter, were internalized by macrophages, likely via endocytic/phagocytic pathways. They were randomly distributed throughout the cytoplasm and mainly located in membrane-bound compartments. Conclusion: Nanoparticles presented an elevated intrinsic loss power value and were not cytotoxic to mammalian cells. Thus, we suggest that low-cost SPIONs have great therapeutic potential.

Magnetic transcutaneous fixation: an experimental study in pigs.

BACKGROUND: Magnetic subdermal implants have never been studied in the context of magnetic fixation of an external device to the body's surface. Excessive attractive force between the implant and the external device may compromise local circulation due to mechanical compression, leading to necrosis. OBJECTIVE: To evaluate the feasibility of transcutaneous magnetic fixation and assess secondary skin changes when subjected to a continuous static magnetic field. METHODS: Using the pig as an animal model, 72 implants were introduced in 12 animals. After wound healing, ultrasonography was performed to measure implant depths. Computer simulations were applied to allow magnetic attachment between implants and external devices without impairing local blood flow. External devices of different magnetic strengths were applied over the skin for 7 days. Local skin was examined and collected for analysis. A senior dermatopathologist blindly examined skin specimens and controls for abnormal findings, measuring dermal and epidermal thickness. Statistical analysis (P <0.05) was performed over the data. RESULTS: Nineteen implants presented extrusion. The remaining 53 skin sites underwent magnetic compression, of which 43 (81%) evolved uneventfully. Implant depth varied between 4.6 mm and 8.3 mm (5.8 mm; ± 8.6 mm) with estimated pressure levels between 13.28 mmHg and 37.04 mmHg (27.6 mmHg; ±6.0 mmHg). Stronger magnets were associated with an increase in dermal thickness (P = 0.011) and neovascularization (P = 0.045). CONCLUSIONS: Transcutaneous magnetic fixation is compatible with skin viability in vivo, under experimental conditions. Skin interposition between two permanent magnets resulted in a continuous static magnetic field stimulation, which showed similar effects to pulsed electromagnetic fields reported on scientific literature.

Tuning of magnetic dipolar interactions of maghemite nanoparticles embedded in polyelectrolyte layer-by-layer films.

In this study we report an experimental approach capable of tuning dipolar interactions in hybrid magnetic nanofilms produced via layer-by-layer assembly of positively-charged maghemite nanoparticles and sodium sulfonated polystyrene onto glass and silicon substrates. Morphological and magnetic properties of the as prepared nanofilms were determined by Raman spectroscopy, atomic force microscopy, conventional and SQUID magnetometry. Maghemite nanoparticles form densely packed layers with voids between particles being filled by polymeric material as observed in atomic force microscopy images. Magnetic hysteresis loops and zero-field-cooled/field-cooled magnetization curves reveal a superparamagnetic behavior at room temperature. The energy barrier for the magnetic moment reversal of the nanofilms has been determined from the frequency dependent ac susceptibility and is related to the gamma-Fe2O3 nanoparticles concentration used in the colloidal dispersion throughout film fabrication. Variations on the interparticle distances have a direct effect on the interparticle dipolar interactions. A less concentrated colloid gives rise to large separated nanoparticles inside the nanofilm with a consequent reduction on the energy barrier for the magnetic moment reversal. The fabrication process exploring the control of the nanoparticle concentration can thus be used to tune the magnetic dipolar interactions in the nanofilms.

Magnetic nanocomposites fabricated via the layer-by-layer approach.

In this study we describe the fabrication and characterization of nanocomposites consisting of layer-by-layer assembled polyaniline, sulfonated polystyrene, and maghemite nanoparticle layers. In order to assemble the starting components via electrostatic interaction, stable magnetic fluid containing maghemite nanoparticles (d approximately = 7 nm) with either positive or negative surface charges was used as source of nanoparticles for the layer-by-layer assembly. The structure, morphology, electrical and magnetic properties of such nanocomposite films were investigated by UV-Vis spectroscopy, atomic force microscopy, electrical, and magnetic measurements. The amount of PANI, PSS and maghemite nanoparticles within the nanocomposite films increased almost linearly with the number of deposited layers. Atomic force microscopy image of typical polyaniline/maghemite nanocomposites reveal nanoparticles adsorbed all over the film surface. The as-produced nanocomposite exhibits electrical conductivity and superparamagnetism behavior at room temperature, the latter confirmed by the absence of magnetic hysteresis.

Aging investigation of cobalt ferrite nanoparticles in low pH magnetic fluid.

In this study, we report on how surface-passivated and nonpassivated cobalt ferrite nanoparticles (8 nm diameter), suspended as ionic magnetic fluids and aged under low pH conditions, revealed different behavior as far as the time evolution of the iron/cobalt cation distribution, crystal quality, coercivity, and saturation magnetization are concerned. Different techniques were used to perform a detailed study regarding the chemical stability, structural stability, and surface and magnetic properties of the suspended nanoparticles as a function of the aging time. Properties of surface-passivated and nonpassivated nanoparticles were investigated by transmission electron microscopy, X-ray diffraction, atomic absorption spectrometry, magnetic measurements, Raman spectroscopy, and Mössbauer spectroscopy. Our data showed that the employed nanoparticle surface passivation process, besides the formation of an iron-rich surface layer, modifies the nanoparticle core as well, improving the crystal quality while modifying the Fe/Co cation distribution and the nanoparticle dissolution rate profile. Magnetic data showed that the saturation magnetization increases for surface-passivated nanoparticles in comparison to the nonpassivated ones, though coercivity decreases after passivation. These two observations were associated to changes in the cation distribution among the available tetrahedral and octahedral sites.