To generate “green hydrogen,” electrochemical water splitting is regarded as the most promising method, which requires highly efficient bifunctional electrocatalysts to accelerate the hydrogen and ...oxygen evolution reactions (HER and OER). Herein, a “d‐electron complementation” principle to develop such candidates is proposed. By taking advantage of the filling characteristics of 3d orbitals, vanadium‐cobalt phosphide (V‐CoP) is synthesized. According to X‐ray absorption fine structure and X‐ray photoelectron spectroscopy investigation, V can disorder the coordination environment of Co, leading to increased/decreased charge density in Co(P)/Co(O). As a result, V‐CoP shows impressive bifunctional activity, which only needs overpotentials of 46 and 267 mV to deliver 10 mA cm−2 for the HER and OER, respectively. Density functional theory calculations reveal that the accelerated H2O dissociation process on the VOx/CoOx/CoP surface and H conversion kinetics on the V‐neighboring CoCo bridge site result in promoted HER activity. Furthermore, the up‐shifted d‐band center of V‐CoOOH endows the V‐neighboring Co site with a lowered energy barrier for the OER. This work serves as a proof‐of‐concept for the application of the “d‐electron complementation” principle, which can be a generalized guideline to design and develop novel highly efficient catalysts.
A “d‐electron complementation” principle is proposed to develop a highly efficient electrocatalyst. As a proof‐of‐concept, V‐Co phosphide is synthesized, which shows V‐determined activity for water splitting. Density functional theory calculations reveal that the high hydrogen evolution reaction activity originates from the charge transfer from V to Co, while the opposite effect is responsible for the high oxygen evolution reaction activity.
Graphene aerogel is prepared for photocatalytic removal of uranium from water under visible light and air atmosphere. The photochemistry property of uranyl itself plays an essential role to generate ...H2O2 with O2 in air, thus to form (UO2)O2·2H2O. The neutral products can evacuate from the surface of GA-200 to regenerate the activity sites in-situ, resulting in a removal capacity of 1050 mg/g.
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•Graphene aerogel (GA) is synthesized with the controlled reduction degree.•GA photocatalyst can remove uranium under visible light and air atmosphere.•The photochemistry property of uranyl was essential during the photocatalytic process.•The (UO2)O2·2H2O products are obtained in air instead of UO2 in oxygen-free atmosphere.•The removal capacity is 1050 mg/g due to the in-situ regeneration of activity sites.
Photocatalysis-assist transition of uranium from soluble ions to insoluble nanoparticles is benefit for the extraction of uranium but has been rarely realized under air atmosphere. Here we developed a novel graphene aerogel (GA), GA-200, for the photocatalytic removal of uranium from water under visible light and air atmosphere for the first time. By controlling the reduction degree, GA-200 remained numbers of functional groups for anchoring uranium and possessed high photocurrent response and narrow band gap to generate and transfer electrons/holes readily. Under visible light irradiation, neutral (UO2)O2·2H2O nanoparticles were formed and could evacuate from the surface of GA-200 to regenerate the active sites in-situ, resulting in a high removal capacity of 1050 mg/g. The mechanism was further studied. It was found that at the presence of O2 in air, the photochemistry property of uranyl itself played an essential role to generate H2O2 and (UO2)O2·2H2O was formed instead of UO2, which was different from that in oxygen-free atmosphere.
Electromagnetically induced transparency like effect, which can form a sharp transmission window within a broad spectrum, has been widely studied due to its potential in many optical devices. In this ...work, unlike traditional couple-ring resonator structure, we propose a new scheme to achieve electromagnetically induced transparency using only one hole-ring resonator. Thus, the proposed scheme can greatly miniaturize the device. At the wavelength of about 1550 nm, the structure can form multiple transparency windows and can behave as a refractive index sensor with high resolution, the figure of merit can reach larger than 530. The proposed scheme can pave the way for many practical applications such as optical sensors, optical switches and slow light devices.
Water Splitting
In article number 2101758, Rui Zhang, Xiangwei Zhu, Xiaoqun Cao, Xiangnan Sun, and co‐workers report a Co‐V phosphide nanoneedle electrocatalyst for efficient overall water splitting, ...which stems from the “d‐electron complementation” effect from V to Co in the matrix. This highlights d‐orbital engineering in developing novel efficient bifunctional electrocatalysts.
A convenient method was developed for rapid determination of Pu in environmental water samples. The analytical procedure involves preconcentration of Pu using TEVA extraction chromatography ...implemented in a vacuum box setup, and measurement of 239+240Pu by low background liquid scintillation counter (LSC). Chromatographic behaviors of plutonium, uranium, thorium, and americium were investigated, and the size of chromatographic column, concentration and flow rate of uploaded medium/washing liquid, and composition of eluent of Pu(Cl−)62−-on TEVA column were explored. The results show that all the above factors affect the adsorption and desorption of Pu(Cl−)62−-on TEVA column. Decontamination factors of more than 1×104 for uranium and 1×103 for thorium and americium were achieved. Chemical yields of plutonium in the overall procedure range from 70% to 98% and a detection limit of 6×10−3 Bq L−1 in 60min counting time for 5L of water samples were obtained. The method has been successfully applied for rapid and effective determination of low level Pu in water samples. The analytical results show a good agreement with the values obtained using the conventional method. Compared with the conventional analytical procedure, the time consumption and labor intensiveness of the new procedure were greatly reduced and the analysis throughput was greatly increased with low analysis cost. The method is applicable to routine and emergency radiometric assays.
En cas d’accidents nucléaires (Tchernobyl, Fukushima) ou d’exposition à de l'uranium appauvri dans des zones de conflit, la décontamination est nécessaire pour réduire au mieux les conséquences de ...l’ingestion de radionucléides. Après une contamination externe ou interne, les actinides solubilisées sont distribués dans les organes cibles (squelette, foie, tissus, reins, etc.) via la circulation sanguine. Compte tenu de cette dispersion, la chélation de ces radionucléides par des ligands biologiques est une méthode efficace de décorporation pour favoriser l'excrétion de ces métaux déposés et ainsi réduire les risques pour la santé. En raison du faible taux de distribution dans les organes cibles (os, foie, reins) de l'acide diéthylènetriaminepentaacétique (DTPA), des agents de chélation ont été synthétisés et testés in vitro ou in vivo. Dans ce projet, plusieurs ligands polyaminophosphonates, (conçus à l'origine pour être des agents de contraste), ont été synthétisés selon leurs propriétés de bio-distribution, de leurs groupes fonctionnels, de leur potentiel site de coordination et de leur lipophilie. Des études structurales et thermodynamiques ont ensuite été effectuées sur les complexes entre l'uranium (VI) et l’europium (III) (comme analogue de l’américium (III) et curium (III)) et les ligands polyaminophosphonates. La sphère de coordination de ces cations a été observée par spectroscopie UV-visible, TRLFS, FT-IR et la spectroscopie d’absorption X (EXAFS). L'étude de l’affinité a été réalisée par spectroscopie UV-visible. Enfin, les spectroscopies UV-visible et TRLFS ont été utilisées d’une part pour tester la stabilité du complexe ligand/uranyle en présence d’un ion métallique et d’autre part pour étudier le système ternaire : ion uranyle/ligand/calmoduline. Ces résultats ont permis de mieux comprendre les mécanismes de chélation et d’évaluer l'affinité chimique de ces ligands polyaminophosphonates pour l'uranium (VI) et l’europium (III). Cela devrait ainsi aider à la conception de nouveaux agents de chélation de plus en plus efficaces du point de vue de la décorporation.
For exposed person who suffers from contamination from nuclear accidents (Chernobyl, Fukushima) or depleted uranium in war zones, decontamination is required to reduce the sequence damage of radionuclide intake. After an external or internal contamination, the solubilized actinides could be distributed to the target organs (skeletal, liver, kidneys tissues, etc.) via the bloodstream. Considering the dispersion, fate and health effect of the actinides, chelation therapy is an effective decorporation method to promote the excretion of deposited actinides to reduce the health risk. Due to the defect on weak distribution rate to the target organs (bone, liver, kidneys) of diethylenetriaminepentaacetic acid (DTPA) which currently used in clinics, plenty chelation agents were synthesized and tested in vitro or in vivo. In this project, several polyaminophosphonates ligands, a series ligand originally designed for MRI contrast and SPECT agents, were synthesized according to the properties of ligand bio-distribution, functional groups, coordination site and lipophilic. Then the structural and thermodynamic studies were done with the complexes between metal ion such as uranium(VI) and europium(III) (as americium/curium(III) analogue), and polyaminophosphonates ligands. The sphere of coordination of these cations was observed by UV-visible spectroscopy, TRLFS, FT-IR and Extended X-Ray Absorption Fine Structure (EXAFS). The affinity study was done with UV-visible spectroscopy. Finally, the UV-visible spectroscopy and TRLFS were used to test the stability of uranyl ligand complex with competition metal ion in biological conditions and to reveal the interactions between the ternary system, uranyl ion/ligand/calmodulin. These results allow to better understand the chemical affinity and possible chelation mechanism of the polyaminophosphonates ligands for the above actinides and therefore to promote the design of new chelation agents.
Development of animal embryos before zygotic genome activation at the mid blastula transition （MBT） is essentially supported by eggderived maternal products. Nodal proteins are crucial signals for ...mesoderm and endoderm induction after the MBT. It remains unclear which maternal factors activate zygotic expression of nodal genes in the ventrotateral blastodermal margin of the zebrafish blastulas. In this study, we show that loss of maternal Eomesodermin a （Eomesa）, a T-box transcription factor, impairs zygotic expression of the nodal genes ndr1 and ndr2 as well as mesodermal and endodermal markers, indicating an involvement in mesendoderm induction. Maternal Eomesa is also required for timely zygotic expression of the transcription factor gene mxtx2, a regulator of nodal gene expression. Eomesa directly binds to the Eomes-binding sites in the promoter or enhancer of ndr1, ndr2, and rnxtx2 to activate their transcrip- tion. Furthermore, human and mouse Nodal genes are also regulated by Eomes. Transfection of zebrafish eomesa into murine embryonic stem cells promotes mesendodermal differentiation with constant higher levels of endogenous Nodal expression, suggesting a conserved function of Eomes. Taken together, our findings reveal a conserved rote of maternal T-box transcription factors in regulating nodal gene expression and mesendoderm induction in vertebrate embryos.
The recently developed single-cell CRISPR screening techniques, independently termed Perturb-Seq, CRISP-seq, or CROP-seq, combine pooled CRISPR screening with single-cell RNA-seq to investigate ...functional CRISPR screening in a single-cell granularity. Here, we present MUSIC, an integrated pipeline for model-based understanding of single-cell CRISPR screening data. Comprehensive tests applied to all the publicly available data revealed that MUSIC accurately quantifies and prioritizes the individual gene perturbation effect on cell phenotypes with tolerance for the substantial noise that exists in such data analysis. MUSIC facilitates the single-cell CRISPR screening from three perspectives, i.e., prioritizing the gene perturbation effect as an overall perturbation effect, in a functional topic-specific way, and quantifying the relationships between different perturbations. In summary, MUSIC provides an effective and applicable solution to elucidate perturbation function and biologic circuits by a model-based quantitative analysis of single-cell-based CRISPR screening data.
The four major RNA adenosine modifications, i.e., m
A, m
A, alternative polyadenylation, and adenosine-to-inosine RNA editing, are mediated mostly by the "writer" enzymes and constitute critical ...mechanisms of epigenetic regulation in immune response and tumorigenesis. However, the cross-talk and potential roles of these "writers" in the tumor microenvironment (TME), drug sensitivity, and immunotherapy remain unknown.
We systematically characterized mRNA expression and genetic alterations of 26 RNA modification "writers" in colorectal cancer (CRC), and evaluated their expression pattern in 1697 CRC samples from 8 datasets. We used an unsupervised clustering method to assign the samples into two patterns of expression of RNA modification "writers". Subsequently, we constructed the RNA modification "writer" Score (WM_Score) model based on differentially expressed genes (DEGs) responsible for the RNA modification patterns to quantify the RNA modification-related subtypes of individual tumors. Furthermore, we performed association analysis for WM_Score and characteristics of TME, consensus molecular subtypes (CMSs), clinical features, transcriptional and post-transcriptional regulation, drug response, and the efficacy of immunotherapy.
We demonstrated that multi-layer alterations of RNA modification "writer" are associated with patient survival and TME cell-infiltrating characteristics. We identified two distinct RNA modification patterns, characterized by a high and a low WM_Score. The WM_Score-high group was associated with worse patient overall survival and with the infiltration of inhibitory immune cells, such as M2 macrophages, EMT activation, and metastasis, while the WM_Score-low group was associated with a survival advantage, apoptosis, and cell cycle signaling pathways. WM_Score correlated highly with the regulation of transcription and post-transcriptional events contributing to the development of CRC. In response to anti-cancer drugs, WM_Score highly negatively correlated (drug sensitive) with drugs which targeted oncogenic related pathways, such as MAPK, EGFR, and mTOR signaling pathways, positively correlated (drug resistance) with drugs which targeted in apoptosis and cell cycle. Importantly, the WM_Score was associated with the therapeutic efficacy of PD-L1 blockade, suggesting that the development of potential drugs targeting these "writers" to aid the clinical benefits of immunotherapy.
Our study is the first to provide a comprehensive analysis of four RNA modifications in CRC. We revealed the potential function of these writers in TME, transcriptional and post-transcriptional events, and identified their therapeutic liability in targeted therapy and immunotherapy. This work highlights the cross-talk and potential clinical utility of RNA modification "writers" in cancer therapy.
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