. 2021 Jul 22;4:898. doi: 10.1038/s42003-021-02183-1

Table 2.

Human upper gastrointestinal model parameters.

Parameter/state variable	Description	Value (range)	Initial value	Units	Source
t	Time	-	-	min
f	Fraction of stomach contents remaining (relative to initial state)	(0.0–1.0)	1	Unitless	Elashoff 1982¹⁸
$β$	Gastric emptying curve shape parameter	1.12	-	Unitless	Elashoff 1982¹⁸
t_1/2	Half gastric emptying time	43.0	-	min	Elashoff 1982¹⁸
Phe_St	Stomach Phe content	-	12108	μmol
TCA_St	Stomach TCA content	-	0	μmol
Cells_St	Stomach SYNB1618 content	-	Dose-dependent	Cells
pH_St	Stomach pH	(1.71–8.0)	-	Unitless
pH₀	Initial stomach pH	6.0	-	Unitless	Simmons 1986²¹
pH_{St_min}	Minimum gastric pH	1.71	-	Unitless	Minekus 1995²⁶
k_pH	Gastric pH decay constant	0.02653	-	min⁻¹	Minekus 1995²⁶
Phe_SI	Small intestinal Phe content	-	30.2	μmol
TCA_SI	Small intestinal TCA content	-	0	μmol
Cells_SI	Small intestinal SYNB1618 content	-	0	Cells
pH_SI	Small intestinal pH	6.5	-	Unitless	Minekus 2014³⁶
Vol_St	Fasted stomach volume	35.0	-	mL	Mudie 2014³⁹
Vol_SI	Small intestinal volume	54.0	-	mL	McConnell 2008²²
$λ$	Small intestinal absorption rate	0.1019	-	min⁻¹	Adibi 1967²⁵