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Biomaterials, like hydroxyapatite (HAp), are the subject of many scientific investigations. Their specific application, however, is determined by the form and some characteristic features of the resulting material. Synthesis methods and optimization procedures leading to a product of predetermined characteristics are therefore of great interest. To broaden the existing knowledge, sonoprecipitation was investigated as a potential method for the production of nanosized HAp particles. The research was carried out in a static mixer (STM) immersed in the ultrasonic bath. The influence of operating conditions, e.g., ultrasonic power PUS (εUS), ultrasonic frequency (fUS), and unit mixing power (εmix), was investigated in terms of nucleation intensity, product quality, and characteristics (particle size distribution (PSD), mean size, shape, etc.). As a result, the optimal conditions for the HAp nanoparticles synthesis (mean size: d~150 nm; length: L1~250 nm; width: L2~80 nm) in the form of needles/whiskers/rods—similar to the shape of the HAp present in natural human bones, free from agglomerates, with negligible signs of particle destruction—were determined. The formation of HAp of smaller sizes (d ≤ 100 nm) and more compact shapes (L1~155 nm, L2~90 nm), useful in bone regeneration processes, was also discussed. [ABSTRACT FROM AUTHOR]

Aim: To investigate the impact of concussion on pupillary function in children by examining pupillometric parameters and assessing for differences in children reporting photosensitivity. Methods: Retrospective chart review was performed of pediatric patients referred for visual symptoms after concussion from 2017 to 2018 seen in a single academic outpatient clinic. Pupillometry data of 92 patients were included. Outcomes were compared to normative pediatric data from the same institution by 2-sample t tests. The association between photosensitivity and each outcome was assessed by use of linear mixed models with photosensitivity as a fixed effect and random patient effect. Results: Outcomes of 181 eyes in 92 concussion patients were averaged by patient and compared to normative values in scotopic conditions. Concussion patients had an average age of 13.8 ± 2.64 years. Average constriction velocity (P =.0008), maximum constriction velocity (P =.0012), and average dilation velocity (P =.0034) were faster in concussion patients, whereas 75% recovery times (P =.0027) was increased. Photosensitivity did not significantly affect measured pupillary responses. Conclusion: Dynamic pupillary responses may be increased in pediatric concussion. Pupillometry may provide insight into the complex pathophysiological changes underlying pediatric concussion. [ABSTRACT FROM AUTHOR]

This paper contains the analysis of mixture homogeneity in two types of static mixers, Koflo and Kenics, based on both experimental and CFD study. The research was also expanded to the recognition of the pipe that was used as a background. The scope of work includes the analysis of the CoV coefficients (as a measure of mixing degree) obtained for the mentioned devices and their comparison. The research showing the impact of such parameters, i.e., pressure drop or L/d ratio on the mentioned mixture homogeneity was also presented. What is more, the axial dispersion model was introduced to describe the devices as non‐ideal reactors. According to this, new relations for the CoV predictions (taking into consideration the turbulence intensity, the deviations from well‐known ideal states, and the mixing elements' shape) were developed. As a result, it was proven that static mixers are highly efficient devices because the obtained CoVs were at around 2 % in the laminar flow and even less than that in the turbulent regime. When the pipe was used, the satisfactory value of the CoV was obtained when the Reynolds number was increased to 2600. [ABSTRACT FROM AUTHOR]

In the paper, the analysis of the precipitation process of calcium fluoride in the selected static mixers was made. The Kenics and Koflo static mixers, as well as an empty pipe as a background, have been taken into consideration. The Kenics and Koflo types have been chosen as their inner shapes convenient for the realization of continuous precipitation processes as incrustation phenomenon and dangerousness of flow blocking are not as high as in other solutions. The main tasks were focused on the recognition of the precipitation kinetics (to get the knowledge of the relative supersaturation, nucleation sources, and mechanisms controlling the crystal growth), determination of conversion efficiency of the chemical reaction by which CaF2 is precipitated, the fluid dynamic conditions on crystal size distribution (CSD), and the identification of particles' destruction sources as well. This paper is a primary work dedicated to the possibilities of a special treatment of the solid phase during its formation in order to obtain the required crystal size distribution (CSD) and to avoid the agglomeration when necessary. The results are very promising. As it will be shown, the special treatment of the precipitated solid substances in static mixers enables to create crystals with the required size and to eliminate the agglomeration phenomenon. [ABSTRACT FROM AUTHOR]

Background: Remote learning during the COVID-19 pandemic caused behavioural changes such as increased screen time and decreased outdoor time. This study aimed to investigate myopia progression in children during the COVID-19 pandemic., Methods: This was a retrospective observational study performed among 2064 patients ages 2-17 with cycloplegic refractions in the months of January 2019-March 2021 at a tertiary children's hospital. Exclusion criteria were a medical history of relevant connective tissue diseases, myopia control treatment, pseudophakia and aphakia., Results: The overall cohort (n=2064) had a mean spherical equivalent (SE) of 0.12±3.70 D in 2019, -0.07±3.95 D in 2020 and -0.49±3.85 D in 2021. The change in mean SE (0.42 D) from 2020 to 2021 was 2.2 times greater than the change (0.19 D) from 2019 to 2020 at baseline. In the cohort of return patients, there was a significant difference in myopic shift between years (F-ratio=14.4, p<0.00001), and a significant change from 2020 to 2021 (p=0.00008) but not from 2019 to 2020. When observing the prevalence of myopia grouped by age, 8-year-old and 17-year-old patients had the greatest increase compared with baseline. When grouped by refractive error, low myopia children (-0.5 D to -3.00 D) displayed the greatest change in mean SE 2020-2021., Conclusions: There was a substantial increase in myopia progression for children in the Chicagoland area after the period of COVID-19 changes. The behavioural changes of home confinement and online learning during the pandemic may explain these findings., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)