Transcriptomic and functional analyses of mitochondrial dysfunction in pressure overload-induced right ventricular failure

Background In complex congenital heart disease patients such as those with tetralogy of Fallot, the right ventricle (RV) is subject to pressure overload, leading to RV hypertrophy and eventually RV failure. The mechanisms that promote the transition from stable RV hypertrophy to RV failure are unknown. We evaluated the role of mitochondrial bioenergetics in the development of RV failure. Methods and Results We created a murine model of RV pressure overload by pulmonary artery banding and compared with sham-operated controls. Gene expression by RNA-sequencing, oxidative stress, mitochondrial respiration, dynamics, and structure were assessed in pressure overload-induced RV failure. RV failure was characterized by decreased expression of electron transport chain genes and mitochondrial antioxidant genes (aldehyde dehydrogenase 2 and superoxide dismutase 2) and increased expression of oxidant stress markers (heme oxygenase, 4-hydroxynonenal). The activities of all electron transport chain complexes decreased with RV hypertrophy and further with RV failure (oxidative phosphorylation: sham 552.3±43.07 versus RV hypertrophy 334.3±30.65 versus RV failure 165.4±36.72 pmol/(s×mL)

Effect of Support Particle Size in Steam Reforming of Ethanol over Co/CeO₂ Catalysts

Co catalysts supported on ceria supports with two different particle sizes, one in the micro- and the other in the nano-range, were investigated for their ethanol and ethylene steam reforming performance. Pre- and post-reaction characterization techniques, including high-resolution transmission electron microscopy, temperature-programmed oxidation, dispersion, pore size measurements, in situ X-ray diffraction (XRD) and X-ray absorption fine structure spectroscopy (XAFS) studies were performed to examine the reducibility of the catalysts. Steady-state-activity testing has shown nanoparticles to have a higher reforming activity for ethanol, but also high ethylene yields. In spite of the high ethylene yields, catalysts supported on nanoparticles proved to be highly resistant to coking while the catalysts supported on larger ceria particles suffered from coke formation. Reforming experiments performed with ethylene showed significant differences in activity and stability. Bare supports were also tested for activity and the nanoparticle support was seen to have high dehydration activity. <i>Operando</i> DRIFTS experiments performed during ESR showed differences in surface species. Pulse experiments performed to use methanol oxidation as a probe reaction suggested differences in the relative abundance of redox sites and basic sites. The bare ceria supports also exhibited significant activity for ethanol dehydration, but not for C–C cleavage. The superior performance of the catalysts supported on nanoparticles is thought to be due to a combination of factors, including increased reducibility, improved metal dispersion, and a difference in relative abundance of redox sites on the surface. All of these properties and, in turn, the catalytic performance, appear to be affected by the particle size of the support

Oxygen Mobility in Pre-Reduced Nano- and Macro-Ceria with Co Loading: An AP-XPS, In-Situ DRIFTS and TPR Study

The size effect of ceria nanoparticles on surface oxygen mobility and formation of surface oxygen vacancies in ethanol steam reforming was investigated. Higher concentration of Ce3+ surface sites of the ceria nano-particles (~4 nm, NP) was observed compared to the micro-particles (~120 nm, MP). Similarly, studies using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) exhibited higher intensity of O1s assigned to the hydroxyl group bonding to Ce3+ and significantly lower intensity for lattice oxygen, stemming from an increase in the number of oxygen vacancies and enhanced oxygen mobility in the nano-ceria under ethanol steam reforming conditions. The presence of fully reduced cobalt particles (Coo) facilitated ceria reduction through hydrogen spillover. The comparison of cerium oxidation states between pre-reduced CeO2 and pre-reduced Co/CeO2 indicated higher extent of reduction of cerium in the case of Co/CeO2 for ethanol steam reforming. These results, together with our previous investigations where higher Ce3+ was observed over CeO2 compared to Co/CeO2 after pre-oxidation treatments, indicate that the initial state of cobalt in Co/CeO2 affects the oxidation state of cerium. Lastly, both nano-ceria and micro-ceria bare supports showed moderate C–C cleavage activities in ethanol steam reforming where better activity was observed over nano-ceria. Formate species were observed predominantly in the DRIFTS spectra of the nano-ceria whereas major species were acetates for micro-ceria. The dissimilarity in the reaction network was attributed to the difference in the number of surface oxygen vacancies. The Co/CeO2-NP catalyst was found more active compared to Co/CeO2-MP with higher hydrogen yield and ethanol conversion

Hydrodechlorination of trichloroethylene over Pd supported on swellable organically-modified silica (SOMS)

The catalytic activity and resistance to poisoning of Pd catalysts supported on swellable organically modified silica (SOMS) were investigated for hydrodechlorination (HDC) of trichloroethylene (TCE). The promising catalytic activity of 1% Pd/SOMS sample was attributed to the high affinity of SOMS for organics and its high hydrophobicity. While latter characteristic repels water, the adsorptive capacity for organics allows TCE dissolved in aqueous media to concentrate inside the pores, in the vicinity of the active sites, thus helping the kinetics. In the liquid phase, using a continuous flow reactor, higher TCE conversion was obtained over the 1% Pd/SOMS compared to the commercial 1% Pd/Al2O3 catalyst. When the pores of 1% Pd/SOMS sample were fully opened by pre-treating it with ethanol prior to the reaction, HDC activity was seen to significantly increase. In the gas phase, the extent of adsorption was less, reducing the concentration of reactants near the active sites. As a result, 1% Pd/SOMS was less active than 1% Pd/Al2O3 for HDC of TCE. To determine their resistance to poisoning, 1% Pd/SOMS and 1% Pd/A1203 catalysts were poisoned ex-situ with Li2S. The ex-situ poisoned Pd/SOMS sample maintained its catalytic activity for HDC of TCE. However, a significant loss in catalytic activity of the Pd/Al2O3 catalyst was observed after poisoning. Protection from aqueous phase sulfide poisoning was attributed to the hydrophobicity of the Pd/SOMS, which would exclude anionic species from the embedded Pd particles. The XPS, STEM and ICP-OES results indicated that when Pd/Al2O3 and Pd/SOMS were treated with 1 M HCI, most of the Pd metal was leached from the Pd/Al2O3 catalyst in contrast to Pd/SOMS, which had negligible leaching. Overall, due to hydrophobicity and high affinity for organics, SOMS has potential as a catalyst scaffold for different reactions in groundwater remediation applications