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• Optimal pumping powers for PEMFC with parallel, serpentine, and bamboo channels are noted. • Effects of PP on current density and pressure difference of PEMFC are studied numerically. • A threshold PP is shown as counterbalanced by increased oxygen flux and water resistance. • Appropriate flow channels for different PP loading are outlined. Pumping power (PP), determined by the resistance of the gaseous reactants flowing in flow fields, significantly affects the net output power density of proton exchange membrane fuel cells (PEMFCs), especially on the air-cooled PEMFCs. No previous studies on the oxygen transport performance of PEMFCs operated at high PPs are available. Novel flow channels are needed to serve the PEMFC applications with intermediate PP. The fluid flow, heat, and mass transport processes in a steady-state PEMFC were simulated using a three-dimensional, two-phase, and non-isothermal model, with the oxygen concentration distributions, its interfacial fluxes, and the so-yielded pressure difference and electric current density being reported. Three flow fields were studied: parallel, serpentine, and a novel bamboo shape. There is a threshold PP above which the current density reaches a plateau, counterbalanced by the increasing resistance built up by water accumulation at the cathode. Both the threshold PP and the maximum current density of the serpentine flow field (0.8 W, 1.83 A cm−2) are higher than those of the parallel flow field (0.1 W, 1.71 A cm−2) since the governing oxygen transport for the former depends on the convection and for the latter, the diffusion. A bamboo shape flow field has been proposed to compensate for the drawback of high PP needed for the serpentine flow field. The threshold PP is reduced to 0.5 W, with a maximum current density of 1.78 A·cm−2. The parallel flow field can be applied at a high mass flow rate and low PP scenario; at a low mass flow rate and high PP case, the serpentine flow field can be applied; in between, the bamboo flow field can be applied to be an appropriate alternative. [Display omitted] [ABSTRACT FROM AUTHOR]

Data on long-term tenofovir alafenamide (TAF) therapy for pregnant women with active chronic hepatitis B (CHB) (immune clearance and reactivation phases, currently and previously diagnosed) and their infants are lacking. Pregnant women with active CHB treated with TAF and tenofovir disoproxil fumarate (TDF) were enrolled in this multicenter prospective study, and infants received immunoprophylaxis. The primary outcomes were rates of adverse (safety) events in pregnant women and defects in infants and fetuses. The secondary outcomes were virologic responses in pregnant women, infants' safety, hepatitis B surface antigen (HBsAg) status, and growth conditions. One hundred three and 104 pregnant women were enrolled and 102 and 104 infants were born in the TAF and TDF groups, respectively. In the TAF group, the mean age, gestational age, alanine aminotransferase level, and viral loads at treatment initiation were 29.3 years, 1.3 weeks, 122.2 U/L, and 5.1 log 10 IU/mL, respectively. TAF was well-tolerated, and the most common adverse event was nausea (29.1%) during a mean of 2 years of treatment. Notably, 1 (1.0%) TAF-treated pregnant woman underwent induced abortion due to noncausal fetal cleft lip and palate. No infants in either group had birth defects. In the TAF group, the hepatitis B e antigen seroconversion rate was 20.7% at postpartum month 6, infants had normal growth parameters, and no infants were positive for HBsAg at 7 months. The TDF group had comparable safety and effectiveness profiles. TAF administered throughout or beginning in early pregnancy is generally safe and effective for pregnant women with active CHB and their infants. [Display omitted] [ABSTRACT FROM AUTHOR]