Using earth abundant transition metal-based compounds to replace noble metal catalysts towards hydrogen evolution from water splitting seems to have great importance worldwide. Compositional modulation and structural design on nanoscale have been hot topics for the optimization of their catalytic properties and have attracted great research interest. In this study, we report Co/CoN Janus nanoparticles embedded in a porous nitrogen doped carbon (Co/CoN-NC) composite catalyst, derived by the heat treatment of a Co2+ containing polymer in ammonia atmosphere. The as-obtained hybrid catalyst showed excellent electrocatalytic activities for the hydrogen evolution reaction in both acidic and basic media, and it delivered a current density of 10 mA cm(-2) at the overpotential of 160 mV in 1 M KOH and 190 mV in 0.5 M H2SO4 electrolyte. In addition, the catalyst could sustain potentiostatic electrolysis for at least 100 hours at 10 mA cm(-2) in both acidic and alkaline solutions. Mechanistic study suggested that the high activity of the composite electrocatalyst originated from the Janus effects between Co and CoN, which enhanced the electron transfer efficiency and led to fast hydrogen adsorption and desorption kinetics.

The effect of black carbon (BC) on air quality and the climate is still unclear, which is partly because of the poor understanding regarding the BC aging process in the atmosphere. In this work, we developed a new approach to simulate the BC mixing state (i.e., other species coated on the BC surface) based on an emissions inventory and back-trajectory analysis. The model tracks the evolution of the BC aging degree (characterized by the size ratio of the whole particle and BC core) during atmospheric transport. Using the models, we quantified the mass-averaged aging degree of total BC particles transported to a receptor (e.g., an observation site) from various emission origins (i.e., 0.25 degrees x 0.25 degrees grids). The simulations showed good agreement with the field measurements, which validated our model calculation. Modeling the aging process of BC during atmospheric transport showed that it was strongly dependent on emission levels. BC particles from extensive emission origins (i.e., polluted regions) were characterized by a higher aging degree during atmospheric transport due to more co-emitted coating precursors. On the other hand, high-emission regions also controlled the aging process of BC particles that were emitted from cleaner regions and passed through these polluted regions during atmospheric transport. The simulations identified the important roles of extensive emission regions in the BC aging process during atmospheric transport, implying the enhanced contributions of extensive emission regions to BC light absorption. This provides a new perspective on the phenomenon of pollution building up in the North China Plain, further demonstrating that this is mainly driven by regional transport and transformation. The simulation of the BC aging degree during atmospheric transport provided more clues for improving air pollution and climate change.

Coal-fired power plants (CPPs) dominate China's energy supply systems. Over the past two decades, the explosive growth of CPPs has led to negative air quality and health impacts in China, and a series of control policies have been implemented to alleviate those impacts. In this work, by combining a CPPs emission database over China (CPED), a regional chemical transport model (WRF-CMAQ), and the integrated exposure-response model, we summarized historical and ongoing emission control policies on CPPs over China, investigated the air quality and health impacts of China's CPPs during 2005-2020, and quantified the benefits of each policy. We found that despite the 97.4% growth of coal-fired power generation during 2005-2015, PM2.5 exposures caused by emissions from China's CPPs decreased from 9.0 mu g m(-3) in 2005 to 3.6 mu g m(-3) in 2015. The active emission control policies have decreased CPPs-induced PM2.5 exposures by 10.0 mu g m(-3) during 2005-2015. We estimated that upgrading end-of-pipe control facilities and early retirement of small and low-efficiency units could respectively reduce PM 2.5 exposures by 7.9 and 2.1 mu g m(-3) during 2005-2015 and avoid 111 900 and 31 400 annual premature deaths. Since 2015, China's government has further required all CPPs to comply with the so-called 'ultra-low emission standards' before 2020 as a major component of China's clean air actions. If the policy is fully deployed, CPPs-induced PM2.5 exposures could further decrease by 2.5 mu g m(-3) and avoid 43 500 premature deaths annually. Our study confirms the effectiveness of tailored control policies for China's CPPs and reveals that those policies have played important roles in air quality improvement in China.

Through phase separation, some proteins form liquid-like condensates or droplets which can flow, fuse, and even deform when pressure is applied. In some cases, the condensates 'mature' to form gel or solid-like structure. Recent studies suggest that the liquid-like condensates form the structural basis for several membrane-less subcellular organelles such as stress granules and other subcellular structures. Here, we review and discuss studies that implicate protein phase separation in the function of the spindle apparatus and centrosomes.

RNA-binding proteins with intrinsically disordered regions (IDRs) such as Rbm14 can phase separate in vitro. To what extent the phase separation contributes to their physiological functions is however unclear. Here we show that zebrafish Rbm14 regulates embryonic dorsoventral patterning through phase separation. Zebrafish rbm14 morphants displayed dorsalized phenotypes associated with attenuated BMP signaling. Consistently, depletion of mammalian Rbm14 downregulated BMP regulators and effectors Nanog, Smad4/5, and Id1/2, whereas overexpression of the BMP-related proteins in the morphants significantly restored the developmental defects. Importantly, the IDR of zebrafish Rbm14 demixed into liquid droplets in vitro despite poor sequence conservation with its mammalian counterpart. While its phase separation mutants or IDR failed to rescue the morphants, its chimeric proteins containing an IDR from divergent phase separation proteins were effective. Rbm14 complexed with proteins involved in RNA metabolism and phase separated into cellular ribonucleoprotein compartments. Consistently, RNA deep sequencing analysis on the morphant embryos revealed increased alternative splicing events as well as large-scale transcriptomic downregulations. Our results suggest that Rbm14 functions in ribonucleoprotein compartments through phase separation to modulate multiple aspects of RNA metabolism. Furthermore, IDRs conserve in phase separation ability but not primary sequence and can be functionally interchangeable.

APEX2 based identification of RnA and DnA at the nuclear lamina

The nuclear lamina (NL) is a meshwork found beneath the inner nuclear membrane. The study of the NL is hindered by the insolubility of the meshwork and has driven the development of proximity ligation methods to identify the NL-associated/proximal proteins, RNA, and DNA. To simplify and improve temporal labeling, we fused APEX2 to the NL protein lamin-B1 to map proteins, RNA, and DNA. The identified NL-interacting/proximal RNAs show a long 3' UTR bias, a finding consistent with an observed bias toward longer 3' UTRs in genes deregulated in lamin-null cells. A C-rich motif was identified in these 3' UTR. Our APEX2-based proteomics identifies a C-rich motif binding regulatory protein that exhibits altered localization in laminnull cells. Finally, we use APEX2 to map lamina-associated domains (LADs) during the cell cycle and uncover short, H3K27me3-rich variable LADs. Thus, the APEX2-based tools presented here permit identification of proteomes, transcriptomes, and genome elements associated with or proximal to the NL.

Nuclear lamin isoforms form fibrous meshworks associated with nuclear pore complexes (NPCs). Using datasets prepared from subpixel and segmentation analyses of 3D-structured illumination microscopy images of WT and lamin isoform knockout mouse embryo fibroblasts, we determined with high precision the spatial association of NPCs with specific lamin isoform fibers. These relationships are retained in the enlarged lamin meshworks of Lmna(-/-) and Lmnb1(-/-) fibroblast nuclei. Cryo-ET observations reveal that the lamin filaments composing the fibers contact the nucleoplasmic ring of NPCs. Knockdown of the ring-associated nucleoporin ELYS induces NPC clusters that exclude lamin A/C fibers but include LB1 and LB2 fibers. Knockdown of the nucleoporin TPR or NUP153 alters the arrangement of lamin fibers and NPCs. Evidence that the number of NPCs is regulated by specific lamin isoforms is presented. Overall the results demonstrate that lamin isoforms and nucleoporins act together to maintain the normal organization of lamin meshworks and NPCs within the nuclear envelope.

Intrinsically disordered proteins (IDPs) effect biological function despite their sequence-encoded lack of preference for stable three-dimensional structure. Among their many functions, IDPs form membraneless cellular compartments through liquid-liquid phase separation (LLPS), also termed biomolecular condensation. The extent to which LLPS has been evolutionarily selected remains largely unknown, as the complexities of IDP evolution hamper progress. Unlike structured proteins, rapid sequence divergence typical of IDPs confounds inference of their biophysical or biological functions from comparative sequence analyses. Here, we leverage mitosis as a universal eukaryotic feature to interrogate condensate evolutionary history. We observe that evolution has conserved the ability for six homologs of the mitotic IDP BuGZ to undergo LLPS and to serve the same mitotic function, despite low sequence conservation. We also observe that cellular context may tune LLPS. The phylogenetic correlation of LLPS and mitotic function in one protein raises the possibility of an ancient evolutionary interplay between LLPS and biological function, dating back at least 1.6 billion years to the last common ancestor of plants and animals.

The ability of a cell to regulate its mechanical properties is central to its function. Emerging evidence suggests that interactions between the cell nucleus and cytoskeleton influence cell mechanics through poorly understood mechanisms. Here we conduct quantitative confocal imaging to show that the loss of A-type lamins tends to increase nuclear and cellular volume while the loss of B-type lamins behaves in the opposite manner. We use fluorescence recovery after photobleaching, atomic force microscopy, optical tweezer microrheology, and traction force microscopy to demonstrate that A-type lamins engage with both F-actin and vimentin intermediate filaments (VIFs) through the linker of nucleoskeleton and cytoskeleton (LINC) complexes to modulate cortical and cytoplasmic stiffness as well as cellular contractility in mouse embryonic fibroblasts (MEFs). In contrast, we show that B-type lamins predominantly interact with VIFs through LINC complexes to regulate cytoplasmic stiffness and contractility. We then propose a physical model mediated by the lamin-LINC complex that explains these distinct mechanical phenotypes (mechanophenotypes). To verify this model, we use dominant negative constructs and RNA interference to disrupt the LINC complexes that facilitate the interaction of the nucleus with the F-actin and VIF cytoskeletons and show that the loss of these elements results in mechanophenotypes like those observed in MEFs that lack A- or B-type lamin isoforms. Finally, we demonstrate that the loss of each lamin isoform softens the cell nucleus and enhances constricted cell migration but in turn increases migration-induced DNA damage. Together, our findings uncover distinctive roles for each of the four major lamin isoforms in maintaining nucleocytoskeletal interactions and cellular mechanics.