3,859 research outputs found
Frequent nuclear expression of ]-catenin protein but rare ]-catenin mutation in pulmonary sclerosing hemangioma.
No full textPrognostic significance of insulin-like growth factor II mRNA-binding protein 3 expression in gastric adenocarcinoma.
No full textCytoplasmic CD24 expression is a novel prognostic factor in diffuse-type gastric adenocarcinoma.
No full textSulfur-Promoted Hydrocarboxylation of Olefins on Heterogeneous Single-Rh-Site Catalysts
No full textSulfur
poisoning is a severe problem in industrial applications,
attracting broad interest in fundamental research studies. Although
a number of studies about sulfur resistance have been implemented
in many reactions on nanoparticle catalysts, few investigations focus
on carbonylation reactions using heterogeneous single-metal-site catalysts
(HSMSCs). Herein, we present an unanticipated sulfur-promoted performance
in olefin hydrocarboxylation reactions on a single-Rh-site catalyst
supported on porous ionic polymers (Rh1/PIPs) with 1000
ppm H2S in CO feed. Ex situ EXAFS and in situ DRIFTS revealed a ternary cycle mechanism of olefin
hydrocarboxylation reactions with Rh–H complexes as predominant
active species in both pure and H2S-containing feedstock.
Moreover, the transformation of the Rh mononuclear complex with the
addition of H2S was also demonstrated. Density functional
theory studies were performed to verify the feasibility of the proposed
pathway and confirm that the energy barriers of transition states
with the sulfur ligand were much lower than those in normal feed,
for example, a decline of 3.4 kcal/mol for the rate-determining step
of migration and insertion of CO. This work provides a distinctive
example for the insight of sulfur effect on carbonylation, which could
be potentially beneficial for further applications of HSMSCs
Autothermal Reforming of Methane Over CeO2-ZrO2-La2O3 Supported Rh Catalyst
No full textAutothermal reforming of methane was studied over La-doped ceria-zirconia-supported Rh catalysts. The CH4 conversion increased from 49 to 60% on increasing the content of La3+ from 5 to 15%, while further increase in the La3+ content led to a slight decrease on both CH4 conversion and H-2 selectivity. H-2-TPR and UV-vis DRS spectrum showed that the interaction between Rh and the support was enhanced by increasing the content of La. We speculated that a so-called "Rh-La interfacial species" was formed on the surface of the support, which played an important role in catalytic activity. The balance between exposed Rh and the "Rh-La interfacial species" was necessary to improve the catalytic activity. Upon increasing the Rh loading on 15% La-doped ceria-zirconia support, the balance was built, i.e., CH4 conversion increased from similar to 60 to 69% by increasing Rh loading from 0.1 to 0.5 wt% and only 2% conversion was elevated by doubling the Rh loading from 0.5 to 1.0 wt%
Unveiling the Structure Sensitivity for Direct Conversion of Syngas to C2-Oxygenates with a Multicomponent-Promoted Rh Catalyst
No full textAbstract: Mn and Li promoted Rh catalysts supported on SiO2 with a thin TiO2 layer were synthesized by stepwise incipient wetness impregnation approach. The thin TiO2 layer on the surface of SiO2 was proved to stabilize those small Rh nanoparticles and hinder their agglomeration. The reducibility of Rh on these catalysts depends on Rh particle size as well as the position of manganese oxide, and large Rh nanoparticles with MnO on Rh nanoparticles can be only reduced at an elevated temperature. Catalyst with large Rh particles exhibits a higher CO conversion and higher products selectivity towards long chain hydrocarbons and C2-oxygenates at the expense of decreasing methane formation than a similar catalyst with smaller Rh particles. This was attributed to the synergistic effect of Mn and Li promotion and molar ratio between Rh0 and Rhδ+ sites on the surface of Rh nanoparticles. Moreover, Rh nanoparticles on MnO are proved to be more efficient in promoting hydrogenation of acetaldehyde to ethanol than its counterpart with MnO on Rh nanoparticles. Finally, in order to target high C2-oxygenates selectivity, low reaction temperature together with a low H2/CO ratio in the feed is recommended. Graphic Abstract: [Figure not available: see fulltext.].ChemE/Catalysis EngineeringChemE/O&O groe
Overexpression of KIAA0101 predicts high stage, early tumor recurrence, and poor prognosis of hepatocellular carcinoma.
No full textDiffuse expression of RNA-binding protein IMP3 predicts high-stage lymph node metastasis and poor prognosis in colorectal adenocarcinoma.
No full text
Computational Exploration of Rh-III/Rh-V and Rh-III/Rh-I Catalysis in Rhodium(III)-Catalyzed C-H Activation Reactions of N-Phenoxyacetamides with Alkynes
No full textThe selective rhodium-catalyzed functionalization of arenes is greatly facilitated by oxidizing directing groups that, act both as directing groups and internal oxidants. We report density functional theory (B3LYP and M06) investigations on the mechanism of rhodium(III)-catalyzed redox coupling reaction of N-phenoxyacetamides with alkynes. The results elucidated the role of the internal oxidizing directing group, and the role of Rh-III/Rh-I and Rh-III/Rh-V catalysis of C-H functionalizations. A novel Rh-III/Rh-V-Rh-III cycle successfully rationalizes recent experimental observations by Liu and Lu et al. (Liu, G. Angew. Chem. Int. Ed. 2013, 52, 6033) on the reactions of N-phenoxyacetamides with alkynes in different solvents. Natural Bond Orbital (NBO) analysis confirms the identity of Rhy intermediate in the catalytic cycle.National Natural Science Foundation of China [21133002, 21203004]; Shenzhen Peacock Program [KQTD201103]; National Science Foundation of the USA [CHE-1361104]; National Science Foundation under the CCI Center for Selective C-H Functionalization [CHE-1205646]; National Science Foundation [OCI-1053575]SCI(E)[email protected]; [email protected]
- …
