Identification of Highly Selective Surface Pathways for Methane Dry Reforming Using Mechanochemical Synthesis of Pd-CeO2.

The methane dry reforming (DRM) reaction mechanism was explored via mechanochemically prepared Pd/CeO2 catalysts (PdAcCeO2M), which yield unique Pd-Ce interfaces, where PdAcCeO2M has a distinct reaction mechanism and higher reactivity for DRM relative to traditionally synthesized impregnated Pd/CeO2 (PdCeO2IW). In situ characterization and density functional theory calculations revealed that the enhanced chemistry of PdAcCeO2M can be attributed to the presence of a carbon-modified Pd0 and Ce4+/3+ surface arrangement, where distinct Pd-CO intermediate species and strong Pd-CeO2 interactions are activated and sustained exclusively under reaction conditions. This unique arrangement leads to highly selective and distinct surface reaction pathways that prefer the direct oxidation of CH x to CO, identified on PdAcCeO2M using isotope labeled diffuse reflectance infrared Fourier transform spectroscopy and highlighting linear Pd-CO species bound on metallic and C-modified Pd, leading to adsorbed HCOO [1595 cm-1] species as key DRM intermediates, stemming from associative CO2 reduction. The milled materials contrast strikingly with surface processes observed on IW samples (PdCeO2IW) where the competing reverse water gas shift reaction predominates.

Direct Identification of Mixed-Metal Centers in Metal-Organic Frameworks: Cu3(BTC)2 Transmetalated with Rh2+ Ions.

Raman spectroscopy was used to establish direct evidence of heterometallic metal centers in a metal-organic framework (MOF). The Cu3(BTC)2 MOF HKUST-1 (BTC3- = benzenetricarboxylate) was transmetalated by heating it in a solution of RhCl3 to substitute Rh2+ ions for Cu2+ ions in the dinuclear paddlewheel nodes of the framework. In addition to the Cu-Cu and Rh-Rh stretching modes, Raman spectra of (CuxRh1-x)3(BTC)2 show the Cu-Rh stretching mode, indicating that mixed-metal Cu-Rh nodes are formed after transmetalation. Density functional theory studies confirmed the assignment of a Raman peak at 285 cm-1 to the Cu-Rh stretching vibration. Electron paramagnetic resonance spectroscopy experiments further supported the conclusion that Rh2+ ions are substituted into the paddlewheel nodes of Cu3(BTC)2 to form an isostructural heterometallic MOF, and electron microscopy studies showed that Rh and Cu are homogeneously distributed in (CuxRh1-x)3(BTC)2 on the nanoscale.

Material Discovery and High Throughput Exploration of Ru Based Catalysts for Low Temperature Ammonia Decomposition.

High throughput experimentation has the capability to generate massive, multidimensional datasets, allowing for the discovery of novel catalytic materials. Here, we show the synthesis and catalytic screening of over 100 unique Ru-Metal-K based bimetallic catalysts for low temperature ammonia decomposition, with a Ru loading between 1-3 wt% Ru and a fixed K loading of 12 wt% K, supported on γ-Al2O3. Bimetallic catalysts containing Sc, Sr, Hf, Y, Mg, Zr, Ta, or Ca in addition to Ru were found to have excellent ammonia decomposition activity when compared to state-of-the-art catalysts in literature. Furthermore, the Ru content could be reduced to 1 wt% Ru, a factor of four decrease, with the addition of Sr, Y, Zr, or Hf, where these secondary metals have not been previously explored for ammonia decomposition. The bimetallic interactions between Ru and the secondary metal, specifically RuSrK and RuFeK, were investigated in detail to elucidate the reaction kinetics and surface properties of both high and low performing catalysts. The RuSrK catalyst had a turnover frequency of 1.78 s-1, while RuFeK had a turnover frequency of only 0.28 s-1 under identical operating conditions. Based on their apparent activation energies and number of surface sites, the RuSrK had a factor of two lower activation energy than the RuFeK, while also possessing an equivalent number of surface sites, which suggests that the Sr promotes ammonia decomposition in the presence of Ru by modifying the active sites of Ru.

Epicardial fat thickness correlates with coronary in-stent restenosis in patients with acute myocardial infarction / La grasa epicárdica se relaciona con la reestenosis del stent en pacientes con infarto agudo de miocardio

Objective: To determine the relation between epicardial fat thickness and coronary in-stent restenosis in patients with acute myocardial infarction and percutaneous coronary intervention. Methods: A prospective study was conducted, which included 129 patients (67.3% male, mean age 62.9 ± 10 years) with ST segment elevation acute myocardial infarction undergoing primary percutaneous coronary intervention with bare metal stent. Patients were divided in two groups according to the presence (n = 21) or not (n = 108) of in-stent restenosis during one year follow-up. Results: Epicardial fat was significantly thicker in patients with coronary in-stent restenosis (5.51 ± 1.6 vs 4.14 ± 2.0 mm, p = 0.006). A proportionally and significantly thicker epicardial fat was found according to the increase in coronary disease severity (3.3 ± 0.9 mm vs 4.3 ± 1.8 mm vs 4.7 ± 2.3 mm vs 6.7 ± 2.2mm, for type A, B1, B2 and C lesions, respectively, p=0.001) and number of vessels (3.07 ± 1.2 mm vs 4.92 ± 1.8 mm vs 5.43 ± 2.2 mm, for one, two and three vessels disease, respectively, p < 0.0001). Epicardial fat thickness ≥ 4.7 mm had 75.0% sensibility and 69.0% specificity for predicting restenosis (AUC = 0.737). Conclusions: Echocardiographic evaluation of epicardial fat thickness could identify those patients with acute myocardial infarction with greater probabilities of in-stent restenosis after percutaneous coronary intervention

Objetivos: Determinar la relación entre el grosor de la grasa epicárdica y la reestenosis del stent en pacientes con infarto agudo de miocardio e intervención coronaria percutánea. Métodos: Se realizó un estudio prospectivo en 129 pacientes (67,3% del sexo masculino, edad media: 62,9 ± 10 años) con diagnóstico de infarto agudo de miocardio con elevación del ST e intervención coronaria percutánea primaria con stent metálico convencional, divididos en 2 grupos según presencia (n = 21) o no (n = 108) de reestenosis durante un año de seguimiento posterior a la intervención. Resultados: La grasa epicárdica fue significativamente mayor en los pacientes con reestenosis del stent (5,51 ± 1,6 vs. 4,14 ± 2,0 mm; p = 0,006), aumento en la severidad de la lesión angiográfica (3,3 ± 0,9 vs. 4, 3± 1,8 vs. 4,7 ± 2,3 vs. 6,7 ± 2,2 mm, para lesiones tipo A, B1, B2 y C, respectivamente; p = 0,001) y el número de vasos enfermos (3,07 ± 1,2vs. 4,92 ± 1,8 vs. 5.43 ± 2.2 mm, para uno, 2 y 3 vasos, respectivamente; p < 0,0001). La grasa epicárdica ≥ 4,7 mm mostró una sensibilidad del 75,0% y una especificidad del 69,0% en la predicción de reestenosis (área bajo la curva de 0,737). Conclusiones: La evaluación ecocardiográfica de la grasa epicárdica puede identificar pacientes con infarto agudo de miocardio con mayores probabilidades de reestenosis del stent después de una intervención coronaria percutánea

Epicardial fat thickness correlates with coronary in-stent restenosis in patients with acute myocardial infarction.

OBJECTIVE: To determine the relation between epicardial fat thickness and coronary in-stent restenosis in patients with acute myocardial infarction and percutaneous coronary intervention. METHODS: A prospective study was conducted, which included 129 patients (67.3% male, mean age 62.9±10 years) with ST segment elevation acute myocardial infarction undergoing primary percutaneous coronary intervention with bare metal stent. Patients were divided in two groups according to the presence (n=21) or not (n=108) of in-stent restenosis during one year follow-up. RESULTS: Epicardial fat was significantly thicker in patients with coronary in-stent restenosis (5.51±1.6 vs 4.14±2.0mm, p=0.006). A proportionally and significantly thicker epicardial fat was found according to the increase in coronary disease severity (3.3±0.9mm vs 4.3±1.8mm vs 4.7±2.3mm vs 6.7±2.2mm, for type A, B1, B2 and C lesions, respectively, p=0.001) and number of vessels (3.07±1.2mm vs 4.92±1.8mm vs 5.43±2.2mm, for one, two and three vessels disease, respectively, p<0.0001). Epicardial fat thickness ≥4.7mm had 75.0% sensibility and 69.0% specificity for predicting restenosis (AUC=0.737). CONCLUSIONS: Echocardiographic evaluation of epicardial fat thickness could identify those patients with acute myocardial infarction with greater probabilities of in-stent restenosis after percutaneous coronary intervention.