Cu-based
catalysts are widely employed for CO or CO2 hydrogenation
into methanol. However, their catalytic performance
highly depends on supports, and the real evolution of Cu species is
still covered by active components. Herein, we supply a Cu/SiO2 catalyst prepared by flame spray pyrolysis (FSP), showing
catalytic performance comparable to that of the active Cu/ZrO2 catalyst for methanol synthesis from CO2. It reaches
79% selectivity at a CO2 conversion of 5.2%, which is an
outstanding selectivity among previously reported Cu/SiO2 catalysts, considering they are generally treated as nearly inert
catalysts. In situ X-ray absorption spectroscopy
(XAS) analysis shows that 5 times more Cu+ species in the
FSP-Cu/SiO2 are stabilized in comparison to those in the
traditional ammonia evaporation (AE) made catalyst even after reduction
at 350 °C. A unique shattuckite-like precursor with a slightly
distorted Cu–O–Si texture structure formed in the FSP-made
catalyst is responsible for the enriched Cu+ species. Variations
of intermediate formation and methanol production are found to have
a good relationship with the amount of Cu+ species. According
to the results of high-pressure in situ DRIFTS, we
attribute this to the promotional effect of Cu+ on the
stabilization of CO* intermediates, which inhibits CO desorption and
facilitates further hydrogenation to CH3OH via the RWGS
+ CO-Hydro pathway. These results bring insights into the Cu reduction
behavior and the function of Cu+ species during methanol
production on Cu-based catalysts without the assistance of active
supports.
The rational design of high-temperature endurable Cu-based catalysts is a long-sought goal since they are suffering from significant sintering. Establishing a barrier on the metal surface by the classical strong metal-support interaction (SMSI) is supposed to be an efficient way for immobilizing nanoparticles. However, Cu particles were regarded as impossible to form classical SMSI before irreversible sintering. Herein, we fabricate the SMSI between sputtering reconstructed Cu and flame-made LaTiO2 support at a mild reduction temperature, exhibiting an ultra-stable performance for more than 500 h at 600 °C. The sintering of Cu nanoparticles is effectively suppressed even at as high as 800 °C. The critical factors to success are reconstructing the electronic structure of Cu atoms in parallel with enhancing the support reducibility, which makes them adjustable by sputtering power or decorated supports. This strategy will extremely broaden the applications of Cu-based catalysts at more severe conditions and shed light on establishing SMSI on other metals.
Long non-coding RNAs (lncRNAs) play important functional roles in various biological processes. Early databases were utilized to deposit all lncRNA candidates produced by high-throughput experimental and/or computational techniques to facilitate classification, assessment and validation. As more lncRNAs are validated by low-throughput experiments, several databases were established for experimentally validated lncRNAs. However, these databases are small in scale (with a few hundreds of lncRNAs only) and specific in their focuses (plants, diseases or interactions). Thus, it is highly desirable to have a comprehensive dataset for experimentally validated lncRNAs as a central repository for all of their structures, functions and phenotypes. Here, we established EVLncRNAs by curating lncRNAs validated by low-throughput experiments (up to 1 May 2016) and integrating specific databases (lncRNAdb, LncRANDisease, Lnc2Cancer and PLNIncRBase) with additional functional and disease-specific information not covered previously. The current version of EVLncRNAs contains 1543 lncRNAs from 77 species that is 2.9 times larger than the current largest database for experimentally validated lncRNAs. Seventy-four percent lncRNA entries are partially or completely new, comparing to all existing experimentally validated databases. The established database allows users to browse, search and download as well as to submit experimentally validated lncRNAs. The database is available at http://biophy.dzu.edu.cn/EVLncRNAs.
Coke‐induced deactivation is one of the major challenges in the field of heterogeneous catalysis. Herein, the performance of the Pt/Al2O3 catalyst for the hydrogen‐free dehydrogenation of cyclohexane was improved by doping with a small amount of Ca. The Ca‐modified Pt/Al2O3 catalyst exhibited a cyclohexane conversion of 97.0 % and maintained a conversion above 75 % after 48 h, whilst the unmodified catalyst was deactivated from 87.0 to 2.7 % under the same conditions. Characterization techniques, including in situ DRIFT, XPS, thermal analysis, and temperature‐programmed techniques, revealed that the presence of Ca effectively suppressed the deep dehydrogenation of H‐rich carbonaceous components and promoted coke desorption by increasing the H/C ratio of H‐deficient coke. This promotion effect of Ca was also associated with neutralizing the residual Cl ions and promoting immediate dehydrogenation.
Most natural protein sequences have resulted from millions or even billions of years of evolution. How they differ from random sequences is not fully understood. Previous computational and experimental studies of random proteins generated from noncoding regions yielded inclusive results due to species-dependent codon biases and GC contents. Here, we approach this problem by investigating 10,000 sequences randomized at the amino acid level. Using well-established predictors for protein intrinsic disorder, we found that natural sequences have more long disordered regions than random sequences, even when random and natural sequences have the same overall composition of amino acid residues. We also showed that random sequences are as structured as natural sequences according to contents and length distributions of predicted secondary structure, although the structures from random sequences may be in a molten globular-like state, according to molecular dynamics simulations. The bias of natural sequences toward more intrinsic disorder suggests that natural sequences are created and evolved to avoid protein aggregation and increase functional diversity.
A zeolite membrane was synthesized on the surface of Pd membrane by seed-free hydrothermal synthesis. The zeolite membrane, which was used as an “armor”, offered good protection to the Pd membranes, significantly suppressing hydrogen permeance loss.
Nano-Fe3O4 accelerated electromethanogenesis on an hour-long timescale by coupling syntrophic acetate oxidation and direct interspecies electron transfer in wetland soil.
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