Samples of healthy and neoplastic myometrial tissues were investigated using Positron Annihilation Lifetime Spectroscopy (PALS). Meaningful differences between normal and diseased tissues were observed for each patient. The differences were also clearly visible for various kinds of lesions in each patient. The set of lifetimes and intensities obtained from PALS was correlated with the histopathological examinations of the same fragments of tissues. Strong coincidence between PALS parameters and histopathological findings was observed only in the case of a very precise correlation of the investigated area in both techniques. Measurements and discussion presented here were carried out to develop a method for measuring the sub-nanometric structure of human tissues. This kind of investigation, using positron probe, creates an opportunity of a new application in Positron Emission Tomography (PET).

Water confined in cylindrical pores of silica with a diameter of 2 nm was studied by positron annihilation lifetime spectroscopy. Instead of freezing at 273 K, the glass-like transition through the viscous state to the solid phase was observed in the wide temperature range of 225–188 K. Reducing the vapor pressure over confined water allowed us to obtain the negative pressure p_n = −164 MPa in liquid water, and the phase transition temperature range changed to 234–189 K. The temperature dependence of the ortho-positronium (o-Ps) lifetime in water under p_n became consistent with the surface tension as in most liquids, as opposed to the anomalous temperature dependence in water under the saturated vapor pressure. This indicates a reduction in the number of hydrogen bonds in confined water under p_n. On this basis, to explain the anomalous temperature dependence, we propose a hypothesis of a partial energy transfer to distant water molecules via the OH-stretching modes instead of repelling the molecules surrounding o-Ps. Our results indicate that thermally generated defects in the confined ice are accompanied by permanent defects, which predominate in the ice formed under p_n. Both types of defects have the same volume of 70 ų, which is much greater than in hexagonal ice I_h. We conjecture that the defects are larger due to the influence of the silanol groups on the structure of solid water. These observations imply that the structure of confined ice differs significantly from that of bulk ice and the vapor pressure influences its formation.

Research conducted in the framework of the J-PET project aims to develop a cost-effective total-body positron emission tomography scanner. As a first step on the way to construct a full-scale J-PET tomograph from long strips of plastic scintillators, a 24-strip prototype was built and tested. The prototype consists of detection modules arranged axially forming a cylindrical diagnostic chamber with the inner diameter of 360 mm and the axial field-of-view of 300 mm. Promising perspectives for a low-cost construction of a total-body PET scanner are opened due to an axial arrangement of strips of plastic scintillators, wchich have a small light attenuation, superior timing properties, and the possibility of cost-effective increase of the axial field-of-view. The presented prototype comprises dedicated solely digital front-end electronic circuits and a triggerless data acquisition system which required development of new calibration methods including time, thresholds and gain synchronization. The system and elaborated calibration methods including first results of the 24-module J-PET prototype are presented and discussed. The achieved coincidence resolving time equals to CRT = 490 ± 9 ps. This value can be translated to the position reconstruction accuracy σ(Δ) = 18 mm which is fairly position-independent Keywords: positron emission tomography, plastic scintillators, J-PET.

Water is the most important life-giving resource on earth. Nowadays, intensive growth of the world population has resulted in increased water consumption and the production of wastewater. Additionally, the presence of pharmaceuticals in treated conventional wastewater or even in the environment is strictly indicating that present techniques of wastewater treatment are not efficient enough and are not designed to remove such pollutants. Scarce water resources in the world are the main driving force for the innovation of novel techniques of water and wastewater treatment. Photocatalysis, as one of the advanced oxidation processes, enables the transformation of recalcitrant and toxic pollutants into CO₂, water, and inorganic salts. In the present paper, the photocatalytic oxidation of β-blockers—metoprolol and propranolol—are described. For photocatalytic oxidation, novel TiO₂ photocatalysts modified with biochar were used. Photocatalysts were prepared by sol-gel method and the effect of photocatalysts type, presence of inorganic ions, dissolved organic matter, and different water matrix was established. The results indicate that using only the decrease in the tested pollutant concentration is not effective enough in establishing the treatment method’s safety. There is a need to use additional testing such as ecotoxicity tests; however, the key parameter is the properly chosen tested organism.