The B cell receptor (BCR) complex plays a critical role in B cell development and immune responses. The assembly mechanisms underlying the BCR complex remain unknown. We determined the cryo–electron microscopy (cryo-EM) structures of human IgG-BCR and IgM-BCR, which consist of membrane-bound immunoglobulin molecules (mIg) and Igα/β subunits at a 1:1 stoichiometry. Assembly of both BCR complexes involves their extracellular domains, membrane-proximal connection peptides, and transmembrane (TM) helices. The TM helices of mIgG and mIgM share a conserved set of hydrophobic and polar interactions with Igα/β TM helices. By contrast, the IgG-Cγ3 and IgM-Cμ4 domains interact with extracellular Ig-like domains of Igα/β through head-to-tail and side-by-side modes, respectively. This work reveals the structural basis for BCR assembly and provides insights into BCR triggering.

Searching for promising HER electrocatalysts is an urgent task for the practical application of hydrogen production by water electrolysis. The Mott–Schottky effect between a metal with larger work function and n-type semiconductor with a higher Fermi level will facilitate the electron transfer from the semiconductor toward the metal. As a result, it is possible to design optimal H* adsorption active sites with thermoneutral hydrogen adsorption free energy (ΔG_H*). Herein, MoC nanoparticles with a diameter of about 3.4 nm embedded in N, P-codoped carbon were converted from well-defined polyoxometalates (around 1 nm) and polypyrrole nanocomposites by carbonization and further wrapped on the surface of CNTs. On the basis of improved electron transfer rate, increased carrier densities, and enhanced active site activities on MoC after lowering the work function due to the Mott–Schottky effect with n-type domains in N, P-codoped carbon, our electrocatalysts could drive the current density of 10 mA cm⁻² at 175 mV with a Tafel slope of 62 mV dec⁻¹ and TOF value of 1.49 s⁻¹ at 150 mV, as well as long-term H₂ production stability. The present study provides a new guideline for the design and preparation of Mott–Schottky HER electrocatalysts.

Microbial fuel cell (MFC) performance is affected by the metabolic activity of bacteria and the extracellular electron transfer (EET) process. The deficiency of nanostructures on macroporous anode obstructs the enrichment of exoelectrogens and the EET. Herein, a N-doped carbon nanowire-modified macroporous carbon foam was prepared and served as an anode in MFCs. The anode has a hierarchical porous structure, which can solve the problem of biofilm blockage, ensure mass transport, favor exoelectrogen enrichment, and enhance the metabolic activity of bacteria. The microscopic morphology, spectroscopy, and electrochemical characterization of the anode confirm that carbon nanowires can penetrate biofilm, decrease charge resistance, and enhance long-distance electron transfer efficiency. In addition, pyrrolic N can effectively reduce the binding energy and electron transfer distance of bacterial outer membrane hemin. With this hierarchical anode, a maximum power density of 5.32 W/m³ was obtained, about 2.5-fold that of bare carbon cloth. The one-dimensional nanomaterial-modified macroporous anodes in this study are a promising strategy to improve the exoelectrogen enrichment and EET for MFCs.