Pocket refractometer

T_core was measured with a rectal thermometer (Ellab Copenhagen, CTD85) inserted 7–10 cm beyond the anal sphincter. Urine specific gravity (USG) was measured before and after completing the EUH and DEH session, using a refractometer (ATAGO, Tokyo, Japan, pocket refractometer, s/no P811580), to ensure that all participants were hydrated (USG<1.020) before starting the trials and in combination with BODY WEIGHT assessment to track changes in hydration over time in the respective trials. In the occupational setting participants were instructed to deliver one urine sample in the morning during mid-day, in the afternoon and/or in the night, corresponding to when the working hours started and/or finished. Body weight was assessed using a platform scale with accuracy down to 0.1 kg (InBody 270, InBody CO Ltd).

CD spectra were measured using a Jasco 810 spectropolarimeter equipped with a Peltier thermoregulation system. Far-UV CD spectra were recorded between 260 and 190 nm with 0.1 mg ml⁻¹ of protein in 20 mM sodium phosphate buffer (Na₂HPO₄/NaH₂PO₄) at pH 7.4 and 1 mm path length. The scanning speed was 20 nm min⁻¹, with data pitch of 0.1 nm. Each spectrum was averaged over 10 scans, and the spectrum of buffer, recorded identically, was subtracted from the protein spectrum. Helicity was calculated from θ₂₂₂ as described (72 (link)). For thermal unfolding, the protein concentration was increased to 1 mg ml⁻¹, and the samples were in a buffer of 20 mM Na₂HPO₄/NaH₂PO_4, pH 7.4, 100 mM NaCl. The signal followed a fixed wavelength of 222 nm in the temperature range of 20 to 90 °C, with data pitch 1 °C and a temperature slope of 1 °C min⁻¹. Spectra were also recorded in the presence of increasing urea concentrations from 0 to 8 M. The urea concentration was measured with a Pocket Refractometer (ATAGO Co). Chemical denaturation was monitored by measuring the ellipticity values at 222 nm. Signals above the maximum value of the high-tension voltage, as provided by the spectropolarimeter manufacturer (600 V), were disregarded. Chemical and thermal denaturation curves were fitted as described later.

Due to the broad concentration range expected in the urine samples during the different prednisolone treatments, quantitation of the various urinary glucocorticoid compounds was based on two eight-point calibration curves (using area ratios), which were prepared in urine matrix. Samples were thereby fortified with all glucocorticoid standards to reach concentrations from 0.50 to 75 ng mL⁻¹ and from 100 to 200 ng mL⁻¹ for cortisol, cortisone, dihydrocortisone, prednisolone, prednisone, methylprednisolone, 20α-dihydroprednisolone, and 20β-dihydroprednisolone. The employed urine matrix was previously verified to contain no residues of prednisolone, prednisone, 20α-dihydroprednisolone and 20β-dihydroprednisolone, but the other glucocorticoids were found to be endogenously present. Therefore, the endogenous concentration levels of cortisol, cortisone, and dihydrocortisone were determined as the average of five non-fortified urine samples and taken into account during quantitation. In addition, since urine is a matrix prone to dilution, normalization by means of the specific gravity (Pocket Refractometer™, Atago, Tokyo) was applied using the Levine-Fahy eq. [23 ].

The content of total soluble solids was periodically measured using a pocket refractometer (Atago Co, Japan) based on a method developed by Booncherm and Siriphanich (1991) .This observation was carried out on the flesh of the durian fruit. By squeezing the flesh until the fruit liquid came out, the three parameters were observed on the prism of a hand-refractometer. Observations were made at each interval of the storage period.

Soluble solids content is measured using a pocket refractometer (ATAGO, Tokyo, Japan). The pulp of the grapes was wrapped in gauze, the juice was squeezed out, and drops were read on the pocket refractometer.