The pick-off annihilation process of ortho-positronium in zeolite ZSM-5 and Silicalite-1 under the influence of gas environment and adsorbed water

2025-12-07T09:16:17+07:00

This study evaluates the influence of gas environments and adsorbed water on the pick-off annihilation process of ortho-positronium (o-Ps) lifetime in zeolite Silicalite-1 and ZSM-5. The results indicate that short-lifetime components (τ₁, τ₂, τ₃) are minimally affected, whereas long-lifetime components (τ₄, τ₅) and annihilation intensity (I₄, I₅) vary significantly depending on the gas environment. Vacuum conditions are optimal for analyzing pore structures, while air significantly reduces o-Ps lifetime due to quenching by O₂. Inert gases such as Ar and N₂ have a lesser impact and can serve as alternatives when vacuum conditions are not available. The effect of adsorbed water is categorized into three drying temperature stages, primarily influencing the τ₅ and I₅ components. Below 200°C, retained water decreases o-Ps lifetime. Between 200°C and 250°C, rapid water desorption from the pores leads to a notable increase in τ₅ and I₅. Beyond 250°C, water is nearly eliminated, and these parameters reach a saturation state. Additionally, Silicalite-1 exhibits higher o-Ps lifetime and annihilation intensity than ZSM-5, reflecting differences in pore size and density between the two materials. These findings highlight the crucial role of environmental conditions in zeolite structure analysis. Vacuum remains the optimal choice for ensuring measurement accuracy, while the influence of adsorbed water must be controlled to prevent measurement deviations.

Effect of storage temperature on the printability of the gelatin - alginate bioink

2025-12-23T15:11:43+07:00

Bioink is a fundamental component of three-dimensional (3D) printing technology, exerting a direct influence on the overall quality, precision, and structural integrity of printed biological constructs. Among various factors influencing printing outcomes, printability is a key determinant for success, as it impacts the precision of printed structures, the consistency of filament formation, and the ability to maintain the correct shape throughout the printing process. The printability of bioink is influenced not only by its composition but also by external conditions, particularly the storage temperature. Therefore, evaluating the impact of storage temperature on bioink printability is essential. This paper presents the evaluation of the effects of three different storage temperature conditions on the printability of gelatin-alginate B-GA bioink over a period of 21 days. These conditions included freezing at -20 ± 1°C, refrigeration at 4 ± 1°C and storage at room temperature of 25 ± 2°C. The printability was assessed by examining various parameters, including the state of the bioink, the ability to form continuous filaments, the uniformity factor (U), the diffusion rate (Df) and the effectiveness of pore formation (Pr). The results showed that the printability of B-GA bioink remained stable during the first 14 days under all three tested storage conditions. However, after 21 days, a significant decline in printability was observed in the cases of freezing and room temperature conditions, proven by the decrease in Pr values of 0.8469 ± 0.0056 and 0.8630 ± 0.0074, respectively. In contrast, refrigeration at 4 ± 1°C allowed the B-GA bioink to retain its printability consistently throughout the entire 21-day period, with a Pr value of 0.908 ± 0.0227. Therefore, in the test, storing B-GA bioink at 4 ± 1°C was the most effective condition for preserving its printability over 21 days.

VNUHCM Journal of Natural Sciences

The pick-off annihilation process of ortho-positronium in zeolite ZSM-5 and Silicalite-1 under the influence of gas environment and adsorbed water

Effect of storage temperature on the printability of the gelatin - alginate bioink