Hydration Status and Fluid Replacement Strategies of High-Performance Adolescent Athletes: An Application of Machine Learning to Distinguish Hydration Characteristics

There are limited data on the fluid balance characteristics and fluid replenishment behaviors of high-performance adolescent athletes. The heterogeneity of hydration status and practices of adolescent athletes warrant efficient approaches to individualizing hydration strategies. This study aimed to evaluate and characterize the hydration status and fluid balance characteristics of high-performance adolescent athletes and examine the differences in fluid consumption behaviors during training. In total, 105 high-performance adolescent athletes (male: 66, female: 39; age 14.1 ± 1.0 y) across 11 sports had their hydration status assessed on three separate occasions—upon rising and before a low and a high-intensity training session (pre-training). The results showed that 20–44% of athletes were identified as hypohydrated, with 21–44% and 15–34% of athletes commencing low- and high-intensity training in a hypohydrated state, respectively. Linear mixed model (LMM) analyses revealed that athletes who were hypohydrated consumed more fluid (F (1.183.85)) = 5.91, (p = 0.016). Additional K-means cluster analyses performed highlighted three clusters: “Heavy sweaters with sufficient compensatory hydration habits,” “Heavy sweaters with insufficient compensatory hydration habits” and “Light sweaters with sufficient compensatory hydration habits”. Our results highlight that high-performance adolescent athletes with ad libitum drinking have compensatory mechanisms to replenish fluids lost from training. The approach to distinguish athletes by hydration characteristics could assist practitioners in prioritizing future hydration intervention protocols.

Re-mineralization potential, shear bond strength and hydration characteristics of experimentally prepared tri-calcium aluminate phase-modified glass ionomer cement on sound and caries-affected dentin (An in vitro/in vivo study)

Background This study aimed to in vivo and in vitro evaluate the remineralization potential and shear bond strength (SBS) of experimentally prepared tri-calcium aluminate (C3A)-modified glass ionomer cements on sound and artificial caries-affected dentin (CAD). A pure tricalcium aluminate (C3A) phase prepared via solid state reaction at elevated temperature from chemically pure calcium carbonate and alumina, to formulate ceramic composite of composition: 75% C3A, 15% CaSO4·2H2O and 10% Bi2O3. The influence of artificial saliva solution on the hydration characteristics and microstructure of the synthesized composite was investigated by X-ray diffraction (XRD) analysis, FTIR spectral analysis, pH determination and scanning electron microscope (SEM) in comparison with distilled water curing medium. Modified cements of C3A glass ionomers (C3A-CGIC) were prepared by addition of the experimentally prepared C3A to the powder component of the conventical glass ionomer cement (CGIC). Five and 10 wt% of C3A- CGICs powder were prepared and compared to CGIC. Cements were applied in prepared class V cavities in rabbits’ teeth either to sound or artificial CAD. All rabbits were killed after 15 days, and then, Ca and P wt% were evaluated at the cement–dentin interface using Energy-Dispersive X-ray Analysis. Specimens for SBS evaluation were prepared for the tested cements bonded either to sound or artificial CAD, then tested using universal testing machine. Results The XRD results indicate that there is an acceleration effect on the hydration reactions and decrease in the rate of conversion process of C3A phase composite due to the presence of free ions in saliva solution which was emphasized by the results of the IR spectral bands of the hydrated paste samples. The SEM micrographs showed a more-dense microstructure with large accumulations of aluminate hydrate crystals of samples cured under saliva solution. Results of the prepared C3A-CGICs showed that 10wt% C3A-GIC group had the highest statistically significant mean Ca, P wt% and SBS values on CAD compared to 5wt% C3A-GIC and CGIC. Conclusions 10 wt% C3A-GIC has a remineralizing effect on artificial CAD under in vivo conditions, plus its improved bonding to dentin compared to CGIC. Thus, it might be promising restorative/base with advanced remineralization potential and adequate bond strength to both sound dentin and CAD.

Circulating Fluidized Bed Fly Ash Mixed Functional Cementitious Materials: Shrinkage Compensation of f-CaO, Autoclaved Hydration Characteristics and Environmental Performance

Circulating fluidized bed (CFB) fly ash is a by-product from CFB power generation, which is hard to utilize in cement because it contains f-CaO and SO3. This work aims to explore the mechanism of the shrinkage compensation of free-CaO (f-CaO) and the autoclaved hydration characteristics and environmental performance of CFB fly ash mixed cementitious materials (CMM). In this work, long-term volume stability of CMM is improved with the addition of CFBFA. These findings suggest that the compressive strength of sample CMM0.5 is the highest under both standard condition (67.21 MPa) and autoclaved condition (89.56 MPa). Meanwhile, the expansion rate (0.0207%) of sample CMM0.5 is the lowest, which proves the shrinkage compensation effect of f-CaO in CFBFA. The main hydration products of CMM0.5 are Ca2SiO4•H2O (C-S-H) gel, CaAl2Si2O7(OH)2•H2O (C-A-S-H) gel and Ca(OH)2. In addition, the high polymerization degree of [Si(Al)O4] and the densified microstructure are presented at the sample CMM0.5. The leaching results indicates that the heavy metals in CMM0.5 satisfies the WHO standards for drinking water due to physical encapsulation and charge balance. Therefore, this investigation provides a novel method of using CFB fly ash in cement.

Early Age Hydration Characteristics of Calcium Sulphoaluminate Cement Mortar Cured at a Temperature Range from −10 to 20°C

With the increasing number of infrastructures constructed in marine and cold regions, research on and applications of calcium sulphoaluminate (CSA) cement have been flourished, but the hydration process of CSA at low temperature has not been systematically investigated. To characterize the influence of low temperature on the hydration characteristics, freshly mixed CSA mortars were cured at −10, −5, 0, 5, and 20°C, respectively. The hydration process was investigated by electrical resistivity, compressive strength, and microstructure analyses. Results show that the hydration process (especially the induction period) is lengthened by low curing temperature. Both the electrical resistivity and compressive strength increase with an increase in the curing temperature. The compressive strength was reduced at a low curing temperature. Among these five curing temperatures, 5°C is the optimal curing temperature. Low temperatures do not change the kinds of hydrates, but reduce their amount. The scanning electron microscopy results illustrate that fewer hydrates fill the pores in specimens cured at low temperatures, while more hydrates form at higher temperatures. Moreover, low curing temperature contributes to the formation of coarse ettringite crystals. For the cement used at low temperature, the induction period should be reduced by adjusting the calcining process and composition proportion.