Abatement of photochemical smog precursors through complete hydrocarbon oxidation over commercial Pd catalysts under fuel-lean conditions with NO promoting effect.

Currently, severe environmental issues have led to a great transition in the automotive industry from internal combustion engine vehicles to electric vehicles, but this transition will take time more than 10 years, which still requires the use of internal combustion engine vehicles. However, these vehicles emit a significant amount of hydrocarbons, in addition to nitrogen oxides (NOx), due to incomplete fuel combustion. They contribute to the formation of photochemical smog when they react with NOx in the presence of sunlight. To effectively remove these hydrocarbons from the exhaust gas of turbo-gasoline engines or diesel engines, we investigated the abatement of propane and iso-pentane, two typical hydrocarbons. In particular, we studied commercial Pd catalysts and revealed how the Pd loading and aging process simulating 4k and 100k mileage affected hydrocarbon abatement abilities, and their phases were identified using characterization technique, including CO chemisorption, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM). We also suggested the reaction pathway for the complete oxidation of propane over Pd catalyst based on the reaction orders of propane and oxygen: Propane adsorbs on O atoms of PdO, and the kinetically relevant C-H bond cleavage step occurs by the interaction with abundant neighboring O atoms of PdO. Finally, the propane and iso-pentane abatement ability of the Pd catalyst aged for 100k mileage were evaluated under realistic exhaust gas conditions, and the effect of each gas component in the realistic exhaust gas was identified; water inhibits the catalytic reaction of hydrocarbons by occupying the active sites, whereas NO catalyzes the hydrocarbon oxidation reaction by either changing the reaction pathway or active sites under fuel-lean conditions. These findings enable us to effectively reduce environmental pollution and facilitate a smoother transition from internal combustion engine vehicles to electric vehicles.

A mortality analysis of septic shock, vasoplegic shock and cryptic shock classified by the third international consensus definitions (Sepsis-3).

INTRODUCTION: This study aimed to compare the 28-day mortality of patients with septic shock, defined by Sepsis-3 criteria and patients with vasoplegic or cryptic shock who are excluded from this new definition. OBJECTIVES: This retrospective observational study was performed using a tertiary emergency department's septic shock registry and investigated the records of patients managed between January 2010 and December 2015. In 2,138 total patients, 1004 (47.0%) had septic shock, 476 (22.2%) had vasoplegic shock and 655 (30.6%) had cryptic shock. RESULTS: There was significant variation in 28-day mortality among the three groups: 23.4% for septic shock, 8.8% for vasoplegic shock and 12.2% for cryptic shock (P < .001). In subgroup analysis of cryptic shock or septic shock according to lactate levels (2-3, 3-4 and >4 mmol/L), the mortality rate increased as lactate increased (cryptic shock: 9.5%, 14.8% and 18.0%; septic shock: 18.6%, 22.6% and 27.0%, respectively; P < .001). Multivariable analysis revealed odds ratios for mortality of 0.31 (95% CI 0.22-0.44; P < .001) for vasoplegic shock and 0.46 (95% CI 0.35-0.61; P < .001) for cryptic shock relative to septic shock. Survival curve analysis showed significant differences among patients with septic shock, vasoplegic shock and cryptic shock (Log rank test: P < .0001). CONCLUSION: The new septic shock definition may be useful for identifying high-risk patients requiring intensive care. However, cryptic shock-associated mortality increased to 18.0% as serum lactate increased, which suggests that some cryptic shock patients may also require intensive management.

Surpassing the single-atom catalytic activity limit through paired Pt-O-Pt ensemble built from isolated Pt1 atoms.

Despite the maximized metal dispersion offered by single-atom catalysts, further improvement of intrinsic activity can be hindered by the lack of neighboring metal atoms in these systems. Here we report the use of isolated Pt1 atoms on ceria as "seeds" to develop a Pt-O-Pt ensemble, which is well-represented by a Pt8O14 model cluster that retains 100% metal dispersion. The Pt atom in the ensemble is 100-1000 times more active than their single-atom Pt1/CeO2 parent in catalyzing the low-temperature CO oxidation under oxygen-rich conditions. Rather than the Pt-O-Ce interfacial catalysis, the stable catalytic unit is the Pt-O-Pt site itself without participation of oxygen from the 10-30 nm-size ceria support. Similar Pt-O-Pt sites can be built on various ceria and even alumina, distinguishable by facile activation of oxygen through the paired Pt-O-Pt atoms. Extending this design to other reaction systems is a likely outcome of the findings reported here.

Triple-layered polyurethane prosthesis with wrinkles for repairing partial tracheal defects.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to develop a triple-layered artificial polyurethane (PU) scaffold with a wrinkled layer for reconstruction of partial tracheal defects. STUDY DESIGN: Animal experiment. METHODS: PU/Pluronic F127 solution was transformed into an asymmetrically porous PU membrane by an immersion precipitation method. The nonporous wrinkled film was prepared by a simple casting of the PU solution on a grooved mold. The triple-layered wrinkled PU scaffolds were fabricated by simple inosculating between the wrinkled film and the porous membranes as in a sandwich (porous/wrinkled/porous structure). Scaffolds were transplanted into 10 New Zealand rabbits after creating tracheal windows. Endoscopic and histological examinations and mechanical tests were performed. RESULTS: The thickness and outer pore size of the prepared triple-layered PU scaffold were ∼1.95 mm and ∼200 µm, respectively. The wrinkled PU scaffold showed better maximum flexural strength compared to the nonwrinkled scaffold (1.03 ± 0.19 vs. 0.56 ± 0.09 MPa). Eight of 10 rabbits survived through all of the examinations and procedures. Endoscopic findings revealed that respiratory mucosa was observed over the scaffold at 3 weeks, and it was an entirely covered scaffold at 6 weeks. The circular framework of the tracheal lumen was maintained in seven of 10 rabbits. Histologic findings showed that ciliated respiratory mucosa covered the surface of the scaffolds. The tensile strength of the scaffold-implanted trachea was lower than that of the normal control. CONCLUSIONS: A wrinkled, triple-layered PU scaffold can be used as a ready-made scaffold for reconstruction of partial tracheal defects. LEVEL OF EVIDENCE: NA.

Adipose-derived stem cell-containing hyaluronic acid/alginate hydrogel improves vocal fold wound healing.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to investigate the regenerative efficacy of an injectable hyaluronic acid/mildly cross-linked alginate hydrogel (HA/ALG hydrogel) containing human adipose-derived mesenchymal stem cells (hAdMSCs) for vocal fold (VF) wound healing. STUDY DESIGN: Animal research. METHODS: HA/ALG hydrogel containing hAdMSCs was injected into the VFs of rabbits immediately after direct injury. Endoscopic evaluations were performed at 1 and 3 months after injury, and functional evaluations of mucosal vibration and viscoelastic properties were carried out posteuthanization at 3 months after injury. Histopathologic and immunohistochemical evaluations of extracellular matrix (ECM) components and of hepatocyte growth factor (HGF) activity were conducted in injured VFs. The engraftment of implanted hAdMSCs was investigated by detecting fluorescent-labeled cells. RESULTS: The administration of hAdMSCs and hAdMSCs in HA/ALG hydrogel produced better macroscopic morphologies than the injection of phosphate-buffered saline (PBS). Histologic evaluations revealed that treatment with hAdMSCs in HA/ALG produced more favorable ECM changes than hAdMSC. In particular, the treatment of hAdMSCs in HA/ALG hydrogel ameliorated excessive deposition of collagen type I and increased HGF activity in regenerating VFs. hAdMSCs in HA/ALG-treated VFs also exhibited functional improvements in viscoelastic properties. hAdMSCs in HA/ALG remained viable in recipient VFs at 1 month after transplantation, and some were observed to be fostered to differentiate into fibroblasts. CONCLUSIONS: The findings of the present study suggest that HA/ALG hydrogel is a promising biomaterial for prolonging the retention time of stem cells in VFs and for promotion of VF wound healing.