The objectives of this study were to determine the effects of dietary glycyl-glutamine (Gly-Gln) on postweaning growth, small intestinal morphology, and immune response of stressed or nonstressed piglets. Pigs (n = 144; initially 4.49 kg and 14 d of age) were randomly allocated to 24 pens (6 pigs/pen) in an environmentally controlled nursery and assigned to Escherichia coli lipopolysaccharide (LPS) challenge (PBS vs. LPS) and Gly-Gln supplementation (0 vs. 0.15%) in a 2 x 2 factorial arrangement of treatments with 6 pens/treatment. The LPS was the stress-inducing agent, and it was injected on d 7 and 14 of the 21-d experiment. Inflammatory challenge with LPS reduced ADG (P < 0.05) and tended to reduce ADFI (P = 0.06) of piglets from d 7 to 21 of the experiment. Supplementation of Gly-Gln increased ADG and G:F from d 0 to 21 (P < 0.05). On d 21 (1 wk after the second LPS injection), there was an LPS challenge x diet Gly-Gln interaction for ADFI (P < 0.05), but it was difficult to ascertain whether Gly-Gln increased ADFI. A trend for an LPS challenge x diet Gly-Gln interaction was observed for ADG (P = 0.07). There were no differences in lymphocyte proliferation among treatments. The LPS challenge increased crypt depth (CD) of the duodenum and decreased the ratio of villus height (VH) to CD of the ileum (P < 0.05) on d 14 (1 wk after the first LPS injection), whereas dietary supplementation of Gly-Gln increased VH of the ileum and VH:CD of the duodenum (P < 0.05). The concentration of peripheral blood IL-1beta was increased by injection of LPS (P < 0.05) and was decreased by dietary Gly-Gln supplementation during the experimental period (P < 0.05); however, there was no interaction of LPS challenge x Gly-Gln addition for IL-1beta concentration. Concentrations of peripheral blood IL-2 tended to increase at d 14 (P = 0.09) and soluble IL-2 receptor tended to decrease at d 7 (P = 0.06) in piglets supplemented with Gly-Gln; therefore, the peripheral blood IL-2/soluble IL-2 receptor system tended to favor the secretion of IL-2 during the first 2 wk of the experiment. In conclusion, considerable suppression of growth and immune function occurred in early weaning piglets challenged with LPS, and such depression could be alleviated by dietary Gly-Gln supplementation independent of the LPS challenge.
Anion exchange membranes (AEMs) with robust alkaline stability and high ionic conductivity are imminently required for the promising electrochemical energy conversion devices – fuel cells.
The
development of anion exchange membranes (AEMs) is hindered
by the trade-off of ionic conductivity, alkaline stability, and mechanical
properties. Tröger’s base polymers (Tb-polymers) are
recognized as promising membrane materials to overcome these obstacles.
Herein, the AEMs made from Tb-poly(crown ether)s (Tb-PCEs) show good
comprehensive performance. The influence of crown ether on the conductivity
and alkaline stability of AEMs has been investigated in detail. The
formation of hydronium ion-crown ether complexes and an obvious microphase-separated
structure formed by the existence of crown ether can enhance the conductivity
of the AEMs. The maximum OH– conductivity of 141.5
mS cm–1 is achieved from the Tb-PCEs based AEM (Tb-PCE-1)
at 80 °C in ultrapure water. The ion-dipole interaction of the
Na+ with crown ether can protect the quaternary ammonium
from the attack of OH– to improve the alkaline stability
of AEMs. After 675 h of alkaline treatment, the OH– conductivity of Tb-PCE-1 decreases by only 6%. The Tb-PCE-1-based
single cell shows a peak power density of 0.202 W cm–2 at 80 °C. The prominent physicochemical properties are attributed
to the well-developed microstructure of the Tb-PCEs, as revealed by
TEM, AFM, and SAXS observations.
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