DNA-Assisted Creation of a Library of Ultrasmall Multimetal/Metal Oxide Nanoparticles Confined in Silica.

Supported ultrasmall metal/metal oxide nanoparticles (UMNPs) with sizes in the range of 1-5 nm exhibit unique properties in sensing, catalysis, biomedicine, etc. However, the metal-support and metal-metal precursor interactions were not as well controlled to stabilize the metal nanoparticles on/in the supports. Herein, DNA is chosen as a template and a ligand for the silica-supported UMNPs, taking full use of its binding ability to metal ions via either electrostatic or coordination interactions. UMNPs thus are highly dispersed in silica via self-assembly of DNA and DNA-metal ion interactions with the assistance of a co-structural directing agent (CSDA). A large number of metal ions are easily retained in the mesostructured DNA-silica materials, and their growth is controlled by the channels after calcination. Based on this directing concept, a material library, consisting of 50 mono- and 54 bicomponent UMNPs confined within silica and with narrow size distribution, is created. Theoretical calculation proves the indispensability of DNA with combination of several organics in the synthesis of ultrasmall metal nanoparticles. The Pt-silica and Pt/Ni-silica chosen from the library exhibit good catalytic performance for toluene combustion. This generalizable and straightforward synthesis strategy is expected to widen the corresponding applications of supported UMNPs.

Synthetic Pt-Fe(OH) x catalysts by one-pot method for CO catalytic oxidation.

Catalytic oxidation is used to control carbon monoxide (CO) emissions from industrial exhaust. In this work, The prepared Pta-Fe(OH) x catalysts (x represents the mass fraction of Pt loading (%), a = 0.5, 1 and 2) by the one-pot reduction method exhibited excellent CO catalytic activity, with the Pt2-Fe(OH) x catalyst, 70% and ∼100% CO conversion was achieved at 30°C and 60°C, respectively. In addition, the Pt2-Fe(OH) x catalyst also showed excellent H2O resistance and hydrothermal stability in comparison to the Pt2/Fe(OH) x catalyst prepared by impregnation method. Characterization results showed that the excellent catalytic performance of the catalysts was mainly attributed to the abundant surface oxygen species and Pt0 the presence of H2O, which promoted the catalytic reaction of CO, and Density functional theory (DFT) calculation showed that this was mainly attributed to the catalytic activity of the hydroxyl (-OH) species on Pt2-Fe(OH) x surface, which could easily oxidize CO to -COOH, which could be further decomposed into CO2 and H atoms. This study provides valuable insights into the design of high-efficiency non-precious metal catalysts for CO catalytic oxidation catalysts with high efficiency.

SINE-Associated LncRNA SAWPA Regulates Porcine Zygotic Genome Activation.

In mice, retrotransposon-associated long noncoding RNAs (lncRNA) play important regulatory roles in pre-implantation development; however, it is largely unknown whether they function in the pre-implantation development in pigs. The current study aims to screen for retrotransposon-associated lncRNA in porcine early embryos and identifies a porcine 8-cell embryo-specific SINE-associated nuclear long noncoding RNA named SAWPA. SAWPA is essential for porcine embryonic development as depletion of SAWPA results in a developmental arrest at the 8-cell stage, accompanied by the inhibition of the JNK-MAPK signaling pathway. Mechanistically, SAWPA works in trans as a transcription factor for JNK through the formation of an RNA-protein complex with HNRNPA1 and MED8 binding the SINE elements upstream of JNK. Therefore, as the first functional SINE-associated long noncoding RNAs in pigs, SAWPA provides novel insights for the mechanism research on retrotransposons in mammalian pre-implantation development.

Elucidating the role of confinement and shielding effect over zeolite enveloped Ru catalysts for propane low temperature degradation.

Volatile organic compounds (VOCs) are the main precursor for ozone formation and hazardous to human health. Light alkane as one of the typical VOCs is difficult to degrade to CO2 and H2O by catalytic degradation method due to its strong C-H bond. Herein, a series of ultrafine Ru nanoclusters (<0.95 nm) enveloped in silicalite-1 (S-1) zeolite catalysts were designed and prepared by a simple one-pot method and applied for catalytic degradation of propane. The results demonstrate that the enveloped Ru1@S-1 catalyst has excellent propane degradation performance. Its T95 is as low as 294 °C with moisture, and the turnover frequency (TOF) value is up to 5.07 × 10-3 s-1, evidently higher than that of the comparison supported catalyst (Ru1/S-1). Importantly, Ru1@S-1 exhibits superior thermal stability, water resistance and recyclability, which should be attributed to the confinement and shielding effect of the S-1 shell. The in-situ DRIFTS result reveals that the propane degradation over Ru1@S-1 follows the Mars-van-Krevelen (MvK) mechanism, where the hydroxy from the framework of zeolite can provide the active oxygen species. Our work provides a new candidate and guideline for an efficient and stable catalyst for the low-temperature degradation of the light alkane VOCs.