A series of ordered mesoporous Ni–Ce–Al
composite
oxides with various cerium contents were synthesized via a one-pot
route: evaporation-induced self-assembly (EISA) strategy and tested
in methane dry reforming for hydrogen and synthesis gas production.
Using this method, the hydrophobic nickel precursor was directly incorporated
into the hydrophobic cores of surfactant micelles, and thus, the highly
dispersed Ni nanoparticles were stabilized inside the mesopore channels
of an alumina matrix. For comparison, Ni-based catalysts were also
prepared by a traditional impregnation method. The characterization
results confirmed that the ordered mesostructures were well maintained
in all of the cerium-incorporated Ni–Al materials (Ce/(Ce +
Al) molar ratio ≤ 3%). The catalyst with a Ce/(Ce + Al) ratio
of 1% exhibited the highest catalytic activity (with CO2 and CH4 initial conversions being 70% and 68% at 700
°C, respectively) and remained stable in a methane dry reforming
reaction. This improved activity can be attributed to the large surface
area and high dispersion and reducibility of Ni nanoparticles, which
were stable because of the stable alumina framework and high oxygen
mobility in these cerium-containing samples. Resistance to carbon
deposition was found over the Ni–Ce–Al catalyst, whereas
amounts of graphitic carbon species were found over the Ni-impregnated
catalysts, which was responsible for deactivation.
Background:
Recent studies have demonstrated the tremendous potential of epicardial fat volume (EFV) to predict obstructive coronary artery disease. We aimed to develop a new model to estimate pretest probability of obstructive coronary artery disease using traditional risk factors with coronary calcium score and EFV and compare it with proposed models in Chinese patients who underwent coronary computed tomography angiography.
Methods:
The new models were derived from 5743 consecutive patients using multivariate logistic regression and validated in an internal cohort using invasive coronary angiography as the outcome and an external cohort with clinical outcome data. Hosmer-Lemeshow goodness-of-fit test, area under the receiver operating characteristic curve, integrated discrimination improvement and net reclassification improvement were calculated to validate and compare the performance of models.
Results:
EFV improved prediction above conventional risk factors and coronary calcium score (area under the receiver operating characteristic curve increased from 0.856 to 0.874, integrated discrimination improvement 0.0487, net reclassification improvement 0.1181,
P
<0.0001 for all). The final model included 5 predictors: age, sex, symptom, coronary calcium score, and EFV. Good internal validation and external validation of the new model were achieved, with positive net reclassification improvement and integrated discrimination improvement, excellent area under the receiver operating characteristic curve and favorable calibration. Further, the new model demonstrated a better prediction of clinical outcome, resulting in a more cost-effective risk stratification to optimize decision-making of downstream diagnosis and treatment.
Conclusions:
Addition of EFV to conventional risk factors and coronary calcium score offered a more accurate and effective estimation for pretest probability of obstructive coronary artery disease, which may help to improve initial management of stable chest pain.
Spinel powders of LiMn 2−x RE x O 4 (RE = La, Ce, Nd, Sm; 0≤x≤0.1) have been synthesized by solid-phase reaction. The structure and electrochemical properties of these electrode materials were characterized by X-ray diffraction (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge-discharge experiment. The part substitution of rare-earth element RE for Mn in LiMn 2 O 4 decreases the lattice parameter, resulting in the improvement of structural stability, and decreases the charge transfer resistance during the electrochemical process of LiMn 2 O 4 . As a result, the cycle ability, 55°C high-temperature and high-rate performances of LiMn 2−x RE x O 4 electrode materials are significantly improved with increasing RE addition, compared to the pristine LiMn 2 O 4 .
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