between the electronic structure and catalytic efficiency of heterogenous catalysts. Dating back to 1930s, the concept of "electronic factor" was proposed by G. M. Schwab to describe the influence of electronic interaction on catalytic behavior of supported catalyst and divided the interaction into two parts, structural and synergetic ones. [4] Electrons transferring between the metal and the support was first under consideration when it came to the catalysis. After that, S. J. Tauster used the term of "strong metal-support interaction" (SMSI) to describe the chemisorption properties of group VIII elements supported by a metal oxide (e.g. SiO 2 , MgO) in 1978. [5] Later the concept was broadened to interaction between any metallic species and support, based on the experimental phenomena. [6] Till that time, based on the early characterization of surface science, researchers had realized that the active site might change during the process from metallic to an SMSI state, which was indicated to be covered or encapsulated by the support. [7] Among many hypotheses concerning the mechanism of SMSI, electron transfer between the metal and the support has been adapted by many researchers, and was confirmed by Rodriguez based on X-ray crystallography and UV photoemission spectroscopy in 1990s. [8] Then almost at the same time that the term of SACs was formally put forward, C. T. Campbell proposed the concept of "electronic metal-support interaction" (EMSI). As Campbell described, the chemical and catalytic properties might be affected by the electronic perturbations (i.e., shifts in the energy of d-band center) due to the EMSI. [9] In other words, the EMSI gave a much more detailed explanation of the enhanced properties of supported catalysts than SMSI, indicating that the study on catalysis was finally pushed to the electronic scale after so many years. [9b,c,10] Unfortunately, for metal particles or clusters, the accurate identification of electronic state is often difficult or even impossible. [11] The most reliable way to overcome the barrier above is to develop the catalyst based on single-atom metal that avoids intrinsic metal effects, including the electronic quantum size effect as well as structure-sensitivity geometrical effect. [12] Therefore, the rise of SACs provides a nearly perfect model to study the EMSI. As the supported metal species downsize to the single atom, the interaction between active site and support is always uniform, which can be much easier to be characterized by both experiment and theoretical calculation. [13] With the help of advanced techniques, for instance, X-ray absorption spectroscopy (XAS), the information about electronic The electronic metal-support interaction (EMSI), which acts as a bridge between theoretical electronic study and the design of heterogenous catalysts, has attracted much attention. Utilizing the interaction between the metal and the support is one of the most essential strategies to enhance electrocatalytic efficiency due to structural and synergetic promotion. To ...
The modulation of electron density is an effective option for efficient alternative electrocatalysts. Here, p‐n junctions are constructed in 3D free‐standing FeNi‐LDH/CoP/carbon cloth (CC) electrode (LDH=layered double hydroxide). The positively charged FeNi‐LDH in the space‐charge region can significantly boost oxygen evolution reaction. Therefore, the j at 1.485 V (vs. RHE) of FeNi‐LDH/CoP/CC achieves ca. 10‐fold and ca. 100‐fold increases compared to those of FeNi‐LDH/CC and CoP/CC, respectively. Density functional theory calculation reveals OH− has a stronger trend to adsorb on the surface of FeNi‐LDH side in the p‐n junction compared to individual FeNi‐LDH further verifying the synergistic effect in the p‐n junction. Additionally, it represents excellent activity toward water splitting. The utilization of heterojunctions would open up an entirely new possibility to purposefully regulate the electronic structure of active sites and promote their catalytic activities.
SummarySexual reproduction is almost universal in eukaryotic life and involves the fusion of male and female haploid gametes into a diploid cell. The sperm-restricted single-pass transmembrane protein HAP2-GCS1 has been postulated to function in membrane merger. Its presence in the major eukaryotic taxa—animals, plants, and protists (including important human pathogens like Plasmodium)—suggests that many eukaryotic organisms share a common gamete fusion mechanism. Here, we report combined bioinformatic, biochemical, mutational, and X-ray crystallographic studies on the unicellular alga Chlamydomonas reinhardtii HAP2 that reveal homology to class II viral membrane fusion proteins. We further show that targeting the segment corresponding to the fusion loop by mutagenesis or by antibodies blocks gamete fusion. These results demonstrate that HAP2 is the gamete fusogen and suggest a mechanism of action akin to viral fusion, indicating a way to block Plasmodium transmission and highlighting the impact of virus-cell genetic exchanges on the evolution of eukaryotic life.
Lead-free double perovskite nanocrystals (NCs) have emerged as a new category of materials that hold the potential for overcoming the instability and toxicity issues of lead-based counterparts. Doping chemistry represents a unique avenue toward tuning and optimizing the intrinsic optical and electronic properties of semiconductor materials. In this study, we report the first example of doping Yb 3+ ions into lead-free double perovskite Cs 2 AgBiX 6 (X = Cl − , Br − ) NCs via a hot injection method. The doping of Yb 3+ endows the double perovskite NCs with a newly emerged near-infrared emission band (sensitized from the NC hosts) in addition to their intrinsic trap-related visible photoluminescence. By controlling the Yb-doping concentration, the dual emission profiles and photon relaxation dynamics of the double perovskite NCs can be systematically tuned. Furthermore, we have successfully inserted divalent Mn 2+ ions in Cs 2 AgBiCl 6 NCs and observed emergence of dopant emission. Our work illustrates an effective and facile route toward modifying and optimizing optical properties of double perovskite Cs 2 AgBiX 6 (X = Cl − , Br − ) NCs with an indirect bandgap nature, which can broaden a range of their potential applications in optoelectronic devices.
Glycosylation is an abundant post-translational modification that is important in disease and biotechnology. Current methods to understand and engineer glycosylation cannot sufficiently explore the vast experimental landscapes required to accurately predict and design glycosylation sites modified by glycosyltransferases. Here we describe a systematic platform for glycosylation sequence characterization and optimization by rapid expression and screening (GlycoSCORES), which combines cell-free protein synthesis and mass spectrometry of self-assembled monolayers. We produced six N- and O-linked polypeptide-modifying glycosyltransferases from bacteria and humans in vitro and rigorously determined their substrate specificities using 3,480 unique peptides and 13,903 unique reaction conditions. We then used GlycoSCORES to optimize and design small glycosylation sequence motifs that directed efficient N-linked glycosylation in vitro and in the Escherichia coli cytoplasm for three heterologous proteins, including the human immunoglobulin Fc domain. We find that GlycoSCORES is a broadly applicable method to facilitate fundamental understanding of glycosyltransferases and engineer synthetic glycoproteins.
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