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Passive NOx adsorbers (PNA) adsorb NOx at low temperatures and release NOx at high temperatures, at which downstream catalytic systems, such as selective catalytic reduction catalysts, operate efficiently and can remove NOx. Pd/CeO2 is a promising catalyst for PNA applications. In this study, the promoting effect of CO on the NOx adsorption ability of Pd/CeO2 at low temperatures was investigated. The amount of NOx adsorbed significantly increased when CO was added to the feed gas. Specifically, during the first 10 min, the amount of adsorbed NOx increased more than six times in the presence of CO. A mechanism for the promoting effect of CO on low-temperature NOx adsorption was suggested by considering the decreased CO oxidation ability with increasing amount of NOx adsorbed over Pd/CeO2. The model proposes that NOx was readily adsorbed by the oxygen vacancies of CeO2 adjacent to the Pd particles, which were generated during CO oxidation, resulting in an increase in NOx adsorption. A better understanding of the CO and NO interactions would contribute to the development of ceria-based PNA materials.

Summary Innate lymphoid cells (ILCs) rapidly undergo expansion in population size and functional maturation in response to cytokines that signal infection, tissue damage or changes in physiology. Optimal ILC responses are shaped, in part, by the microbiota but the mechanisms remain unclear. We report that short-chain fatty acids (SCFAs), produced by the commensal microbiota from dietary fibers, support optimal expansion of ILCs, including ILC1, ILC2 and ILC3 in the intestines through their G-protein-coupled receptors (GPCRs). While this function is primarily important for intestinal ILC populations, it can also boost ILC responses in other tissues depending on host condition. ILCs express multiple GPCRs that detect SCFAs. Interestingly, we found that the expression of SCFA receptors, such as Ffar2 and Ffar3, by ILCs is induced by SCFAs. GPCR triggering by SCFAs co-stimulates the activation of Phosphoinositide 3-kinase (PI3K), Stat3, Stat5, and mammalian target of rapamycin (mTOR), which is important for ILC proliferation. While Ffar2 signaling promotes ILC2 proliferation, SCFAs can suppress ILC2 proliferation through a non-Ffar2-mediated mechanism. In conclusion, our findings indicate that SCFAs, as the major mediator of healthy microbiota and nutritional status, function to maintain optimal numbers of ILCs in peripheral tissues during infection and inflammatory responses.

Vitamin A metabolites play important roles in T cell activation and differentiation. A conventional model of RARα function relies upon retinoic acid (RA)-liganded RARα binding to specific DNA motifs to regulate gene expression in the nucleus. However, this genomic function fails to explain many of the biological responses of the RA-RARα axis on T cells. We generated a mouse line where RARα is over-expressed in T cells to probe RARα function with unprecedented sensitivity. Using this model together with mice specifically lacking RARα in T cells, we found that RARα is required for prompt exit from metabolic quiescence in resting T cells upon T cell activation. The positive effect of RARα on metabolism is mediated through PI3K and subsequent activation of the Akt and mTOR signaling pathway. This largely non-genomic function of RARα is surprisingly ligand-independent and controls the differentiation of effector and regulatory T cell subsets.

Background This study group has previously identified IL-9–producing mucosal mast cell (MMC9) as the primary source of IL-9 to drive intestinal mastocytosis and experimental IgE-mediated food allergy. However, the molecular mechanisms that regulate the expansion of MMC9s remain unknown. Objectives This study hypothesized that IL-4 regulates MMC9 development and MMC9-dependent experimental IgE-mediated food allergy. Methods An epicutaneous sensitization model was used and bone marrow reconstitution experiments were performed to test the requirement of IL-4 receptor α (IL-4Rα) signaling on MMC9s in experimental IgE-mediated food allergy. Flow cytometric, bulk, and single-cell RNA-sequencing analyses on small intestine (SI) MMC9s were performed to illuminate MMC9 transcriptional signature and the effect of IL-4Rα signaling on MMC9 function. A bone marrow–derived MMC9 culture system was used to define IL-4–BATF signaling in MMC9 development. Results Epicutaneous sensitization– and bone marrow reconstitution–based models of IgE-mediated food allergy revealed an IL-4 signaling-dependent cell-intrinsic effect on SI MMC9 accumulation and food allergy severity. RNA-sequencing analysis of SI-MMC9s identified 410 gene transcripts reciprocally regulated by IL-4 signaling, including Il9 and Batf. In silico analyses identified a 3491-gene MMC9 transcriptional signature and identified 2 transcriptionally distinct SI MMC9 populations enriched for metabolic or inflammatory programs. Employing an in vitro MMC9-culture model system showed that generation of MMC9-like cells was induced by IL-4 and this was in part dependent on BATF. Conclusions IL-4Rα signaling directly modulates MMC9 function and exacerbation of experimental IgE-mediated food allergic reactions. IL-4Rα regulation of MMC9s is in part BATF-dependent and occurs via modulation of metabolic transcriptional programs.

Cu-based catalysts have been variously used in the water gas shift reaction (WGSR) and methanol synthesis, both of which use carbon monoxide as a common reactant. According to the Bell–Evans–Polanyi principle, CO adsorption energies (Eads,CO) directly affect the activation energies for CO hydrogenation. Thus, the understanding of the relationship between Eads,CO and the chemical properties of the catalytic surface is fundamental to catalyst design. In particular, recent studies have shown that effective catalysts can be developed by controlling the exposed facets or forming alloys with other transition metal to enhance the mechanical and electronic characteristics. In bimetallic catalysts, two types of chemical effects are known to determine the adsorption energies: one is the “strain” effect caused by lattice mismatch and the other is the “ligand” effect, generated by the change in orbital electrons. We conducted calculations on Cu/M(100), (111), and (211) surfaces (M = Ni, Ir, Pd and Pt) by using spin-polarized density functional theory (DFT) calculations to find the dominant factor, as well as trends, affecting CO adsorption. Our calculations suggest the ligand effect is the dominant contribution to Eads,CO, regardless of the type of facets. We also determined that the ligand contribution is caused by the loss of electrons from the surface Cu atoms. As a result, a proportional correlation between ligand contribution and electron charge transfer was observed. On investigating the strain effect on the (111) facet, we found that the results are consistent with d-band theory, while the Eads,CO on (100) and (211) facets showed the opposite trend.

Atomically dispersed Pd in Zeolites can adsorb NO to reduce NOx emission from vehicle exhausts at low temperature. In this contribution, low temperature NO adsorption abilities of Pd/ZSM-5 and Pd/SSZ-13 are comparatively studied. Co-adsorption of NO and H2O on Pd/ZSM-5 induced PdO sintering and deactivated NO adsorption ability. On the other hand, NO adsorption ability of Pd/SSZ-13 was maintained from the 500 °C treatment under NO and H2O where PdO sintering did not occur. Therefore, Pd/SSZ-13 would be the better candidate as NO storage material to reduce NOx emission from vehicle exhaust.

Natural or synthetic materials designed to adhere to biological components, bioadhesives, have received significant attention in clinics and surgeries. As a result, there are several commercially available, FDA-approved bioadhesives used for skin wound closure, hemostasis, and sealing tissue gaps or cracks in soft tissues. Recently, the application of bioadhesives has been expanded to various areas including musculoskeletal tissue engineering and regenerative medicine. The instant establishment of a strong adhesion force on tissue surfaces has shown potential to augment repair of connective tissues. Bioadhesives have also been applied to secure tissue grafts to host bodies and to fill or seal gaps in musculoskeletal tissues caused by injuries or degenerative diseases. In addition, the injectability equipped with the instant adhesion formation may provide the great potential of bioadhesives as vehicles for localized delivery of cells, growth factors, and small molecules to facilitate tissue healing and regeneration. This review covers recent research progress in bioadhesives as focused on their applications in musculoskeletal tissue repair and regeneration. We also discuss the advantages and outstanding challenges of bioadhesives, as well as the future perspective toward regeneration of connective tissues with high mechanical demand.