Viorel Nastasa

Marine mollusk shells are a promising renewable source of calcium-based materials, offering a sustainable alternative for their synthesis. In this study, five types of marine shells—Chamelea gallina, Mya arenaria, Rapana venosa, Mytilus edulis, and Pecten maximus—were calcined at 900 °C for 2 h. The resulting powders were characterized by XRD, FTIR, SEM, PSD, and zeta potential analyses. XRD confirmed the dominant presence of CaO, with residual calcite and portlandite. FTIR spectra supported these findings, indicating the decomposition of carbonate phases and the formation of Ca–O bonds. SEM imaging revealed species-specific microstructures ranging from lamellar and wrinkled textures to compact aggregates, while particle size distributions varied from 15 to 37 μm. Thermogravimetric analysis revealed a two-step decomposition process for all samples, with significant species-dependent differences in mass loss and conversion efficiency, highlighting the influence of biogenic origin on the thermal stability and CaO yield of the resulting powders. Zeta potential measurements showed low colloidal stability, with the best performance found in Rapana venosa and Pecten maximus calcinated samples. Antibacterial activity was evaluated using a direct contact method against Escherichia coli and Enterococcus faecalis. All samples exhibited complete inactivation of E. coli, regardless of exposure time, while E. faecalis required prolonged contact (3.3 h) for full inhibition. The results highlight the potential of biogenic CaCO₃ and CaO powders as functional, antimicrobial materials suitable for environmental and biomedical applications. This study underscores the viability of marine shell waste valorization within a circular economy framework.

This study explores a novel photodynamic therapy approach using scintillating nanoparticles activated by laser-driven ionizing radiation. The method enables deep-tissue treatment with ultra-high dose rates, offering potential advances in targeted cancer therapy and FLASH radiobiology.

This paper reports results obtained using white light diffraction phase microscopy (wDPM) on captured images of breast and colon tissue samples, marking a contribution to the advancement in biomedical imaging. Unlike conventional brightfield microscopy, wDPM offers the capability to capture intricate details of biological specimens with enhanced clarity and precision. It combines high resolution, enhanced contrast, and quantitative capabilities with non-invasive, label-free imaging. These features make it a useful tool for tissue imaging, providing detailed and accurate insights into tissue structure and dynamics without compromising the integrity of the samples. Our findings underscore the potential of quantitative phase imaging in histopathology, in the context of automating the process of tissue analysis and diagnosis. Of particular note are the insights gained from the reconstructed phase images, which provide physical data regarding peripheral glandular cell membranes. These observations serve to focus attention on pathologies involving the basal membrane, such as early invasive carcinoma. Through our analysis, we aim to contribute to catalyzing further advancements in tissue (breast and colon) imaging.

This paper presents a spectroscopic study of emulsions generated with a laser-assisted device. Fourier transform infrared (FTIR), Raman and UV–Vis–NIR reflectance spectra of emulsions, recorded before and after exposure to laser radiation were used to characterize the effect of laser irradiation. The paper also presents a comparison between the calculated IR spectra and the experimental FTIR spectra of an emulsion’s components. FTIR measurements allowed the identification of absorption bands specific to each of the emulsions’ components. Moreover, it enabled the observation of destabilization of the emulsion in real-time. Raman spectroscopy allowed the observation of the modifications at a molecular level, by identifying the vibrations of the representative functional groups and the polymerization of sodium tetradecyl sulfate (STS) molecules by analyzing the evolution of the carbonyl band. UV–Vis–NIR reflectance spectra of emulsions before and after exposure to laser radiation showed that the physical characteristics of the emulsions changed during irradiation—the dimensions of the droplets decreased, leading to an emulsion with a better time stability. These results proved that the employed spectroscopy techniques were powerful tools in emulsion analysis.

Optogenetics has emerged as an exciting tool for manipulating neural activity, which in turn, can modulate behavior in live organisms. However, detecting the response to the optical stimulation requires electrophysiology with physical contact or fluorescent imaging at target locations, which is often limited by photobleaching and phototoxicity. In this paper, we show that phase imaging can report the intracellular transport induced by optogenetic stimulation. We developed a multimodal instrument that can both stimulate cells with high spatial resolution and detect optical pathlength changes with nanometer scale sensitivity. We found that optical pathlength fluctuations following stimulation are consistent with active organelle transport. Furthermore, the results indicate a broadening in the transport velocity distribution, which is significantly higher in stimulated cells compared to optogenetically inactive cells. It is likely that this label-free, contactless measurement of optogenetic response will provide an enabling approach to neuroscience.

Phenothiazine exposed to white light or UV radiation undergoes a variety of reactions that result in the degradation of the parental compound and the formation of new species. Chlorpromazine exposed to the 266 nm laser beam of given energy levels yielded species derived from it, whose number increased with the exposure duration. At distinct time intervals the irradiation products were evaluated by spectrophotometry between 200-1500 nm, Thin Layer Chromatography, and for antimicrobial activity of Chlorpromazine against different test organisms such as Staphylococcus aureus.

The multiple resistances to treatment, developed by bacteria and malignant tumors require finding alternatives to the existing medicines and treatment procedures. One of them is strengthening the effects of cytostatics by improving the delivery method. Such a method is represented by the use of medicines as micro/nano-droplets. This method can reduce the substance consumption by generating drug micro-droplets incorporated in substances that can favour a faster localization, than the classical mode of medicine administration, to the tumor tissues. This paper contains the results concerning the generation and study of micro/nano-droplets and the generation of micro-droplets with an inner core (medicine) and a thin layer covering it. We have measured the surface tension at water/air interface and water/oil interface for a medicine (Vancomycin) and we have generated and measured droplets of medicine containing a layer of Vitamin A by using a double capillary system. The micro/nano-droplets may be produced by mixing of two immiscible solutions in particular conditions (high rotating speed and/or high pressure difference). For this we have studied the generation of emulsions of vitamin A diluted in sunflower oil and a solution of a surfactant Tween 80 in distilled water. The concentration of surfactant in water was typically 4*10^-5M. We have studied in a batch stirred tank system the dependence of the droplet dimensions in emulsion, function of the mixing rotation speed, agitation time and components ratio. The droplet diameters were measured using a Malvern light scattering instrument type Mastersizer Hydro 2000M. We have obtained droplets with diameters smaller than 100 nm; the diameters distribution exhibited a peak at 65 nm.