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Gd 3+ - free carbon dots (CDs) were synthesized by one-step solvothermal method using urea, citric acid and 3-(trifluoromethyl)aniline as precursors. Additionally, Gd 3+ -doped CDs were prepared by incorporating gadolinium chloride (Gd 3+ ions) into the synthesis. Size selection of the purified CDs was achieved through filter membranes ranging from 3 kDa to 100 kDa. The chemical composition and optical properties of the obtained samples were characterized by Energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), Dynamic Light Scattering (DLS), proton relaxation time measurements, Ultraviolet-visible (UV-vis) and fluorescence spectroscopies. A comparative analysis revealed a strong size-dependent behavior in the optical properties of both Gd 3+ -doped and Gd 3+ -free CDs. Furthermore, in vitro tests confirmed the non-cytotoxicity of Gd 3+ -doped CDs, indicating their potential applicability in biomedicine for magnetic resonance imaging (MRI) and red fluorescence-based cell and tissue imaging., Competing Interests: Declarations Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

The aim of the present study was to evaluate the use MRI to quantify the workload of gluteus medius (GM), vastus medialis (VM) and vastus lateralis (VL) muscles in different types of squat exercises. Fourteen female volunteers were evaluated, average age of 22 ± 2 years, sedentary, without clinical symptoms, and without history of previous lower limb injuries. Quantitative MRI was used to analyze VM, VL and GM muscles before and after squat exercise, squat associated with isometric hip adduction and squat associated with isometric hip abduction. Multi echo images were acquired to calculate the transversal relaxation times (T2) before and after exercise. Mixed Effects Model statistical analysis was used to compare images before and after the exercise (ΔT2) to normalize the variability between subjects. Imaging post processing was performed in Matlab software. GM muscle was the least active during the squat associated with isometric hip adduction and VM the least active during the squat associated with isometric hip abduction, while VL was the most active during squat associated with isometric hip adduction. Our data suggests that isometric hip adduction during the squat does not increase the workload of VM, but decreases the GM muscle workload. Squat associated with isometric hip abduction does not increase VL workload.