In state-of-the-art positron emission tomography (PET), information about annihilation photon polarization is unavailable. Here, we present a PET scanner built from plastic scintillators, where annihilation photons primarily interact via the Compton effect, providing information about both photon polarization and propagation direction. Using this plastic-based PET, we determined the distribution of the relative angle between polarization planes of photons from positron-electron annihilation in a porous polymer. The amplitude of the observed distribution is smaller than predicted for maximally quantum entangled two-photon states but larger than expected for separable photons. This result can be well explained by assuming that photons from pick-off annihilation are not entangled, while photons from direct and parapositronium annihilations are maximally entangled. Our result indicates that the degree of entanglement depends on the annihilation mechanism in matter, opening avenues for exploring polarization correlations in PET as a diagnostic indicator.

The tanks designed for liquefied natural gas transport must be thermally insulated from the environment due to the low condensing temperature of the gas. The effectiveness of thermal insulation significantly affects the tank's operating parameters and its operating costs. As there is no perfect insulation, there is a need for analyses that would determine its suitability in specific applications. In this paper the issue of heat transfer through double-walled cryogenic tanks with evacuated insulation system was discussed. Afterwards the study of insulation variants of liquefied natural gas cryogenic road tanker was presented. The use of several layers of insulation made of modern and efficient materials such as aero-gel and fiberglass or the use of multi-layer isolation has been considered and compared to the use of perlite powder. The heat flux through insulation systems was tested for different variants of evacuated insulation under residual gas pressure of 10-1 Pa, 10-3 Pa, and 100 kPa. Finally, for selected insulation variants, the heat leakage was tested for 50 m3 liquefied natural gas road tanker. The investigation of heat-flow for the transient thermal analysis was performed by applying finite element method. The aim of the study was to determine the variant of insulation system with the relatively low heat leakage to the tank and low cost of materials and vacuum production.

Objective: Positron emission tomography (PET) is a widely used medical imaging technique that allows for non-invasive imaging of metabolic processes. However, traditional PET scanners rely on costly inorganic scintillators that limit their accessibility, especially in light of emerging long axial field-of-view devices. The modular J-PET scanner, an innovative alternative, uses 50-cm-long plastic scintillator strips, offering a cost-effective and modular solution. In this study we develop and assess the PET data correction techniques required for quantitative image reconstruction. Methods: We present methods for attenuation correction, random coincidence correction using the delayed time window (DTW) technique and scatter correction based on Monte Carlo simulations. Phantom studies using the NEMA IQ phantom were performed to qualitatively evaluate these corrections. Results: The results demonstrate that our implemented corrections for attenuation and random and scattered coincidences successfully improve the uniformity of tracer distribution in homogenous volumes and significantly reduce undesired activity in cold regions. Despite limitations in sensitivity and axial resolution, the applied correction techniques effectively enhance image quality, providing promising results for future applications. Conclusions: These findings highlight the potential of the modular J-PET system to offer affordable PET imaging and to pave the way for a total-body PET scanner based on plastic scintillators. Future work will focus on quantitative validation and the implementation of these corrections for human subject imaging.

Transport and storage of liquefied natural gas (LNG) requires special double-walled cryogenic tanks. To provide a liquid state of LNG throughout entire storage time a temperature inside the tank should be equal −160 °C under the pressure of around 7 bar. Maintaining these parameters requires a vacuum insulation system and internal supports designed to minimize heat leakage into the tank. Additionally, the internal supports must be able to transfer complex mechanical loads that may occur during the operation of the tanker. Combinations and values of directional mechanical loads and thermal loads, to be accepted in designing mobile cryogenic tanks, are determined by proper vessels standards. In this paper, we proposed the construction of internal supports for 25 m³ road tanker, which structure allows to reduce heat leakage into the internal tank, while transferring the complex mechanical loads. Tests of the presented solutions were carried out applying both mechanical and thermal finite element analysis using ANSYS software.

This paper presents the results of numerical and experimental studies of wind action on longitudinal finned tubes of LNG ambient air vaporizers. The main objective of the study was to determine the aerodynamic drag coefficients for longitudinal finned tubes with different number of fins considering various directions of wind action. Numerical calculations were performed using CFD analysis, while experimental tests were carried out in a wind tunnel test stand. The obtained results indicate the variation of tube loads depending on the number of fins and the direction of wind action and can be used in the design of ambient air vaporizers.

The article presents the results of computational fluid dynamics (CFD) analysis of the wind action on liquefied natural gas (LNG) ambient air vaporizers (AAVs). A study concerning AAV with a 6 × 6 tubes array is presented to demonstrate how the distribution of longitudinal finned tubes and wind direction affect the average load and wind pressure acting on the vaporizer structure. The main goal of the study is to estimate the wind load on the structure and wind pressure on individual tubes depending on the pitch of the tubes arrangement. The above parameters are crucial for the strength analysis of the vaporizer structure. The derived analysis results provide important data on the variation of pressure on individual tubes, wind velocity inside AVV structure and indicate a significant increase in the average wind load acting on the structure for a wind direction of 45 degrees compared to a perpendicular direction.