Design Principles of Transition Metal X-ide Catalysts for Electrochemical Oxygen Reduction and Evolution Reactions: In-Situ X-ray Spectroscopy Studies

Hydrogen is the green fuel that can be produced from water through electrolysis and used via hydrogen fuel cells to generate electricity with zero carbon dioxide emission. The commercialization of electrolyzers and fuel cells is the critical step to achieving global carbon neutrality. However, it is severely hampered by the low efficiency in associated reactions, particularly the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) for the two devices, respectively. Highly efficient electrocatalysts are required to overcome the slow kinetics in the two reactions, but the state-of-the-art electrocatalysts are mostly based on noble metal or noble metal oxides such as Pt, IrO2, and RuO2. Therefore, many efforts have been devoted to finding cost-effective and highly active electrocatalysts for ORR and OER. The two most efficient methods are either maximizing noble metal’s activity (e.g., single atom catalysts) or replacing noble metal with low-cost transition metals. This Ph.D. thesis is focused on electrocatalysts containing transition metals, so-called transition metal X-ides (X = C, N, O, S, Se, etc.). Besides the electrochemical characterization of catalysts’ activity, selectivity and stability, we apply synchrotron X-ray absorption spectroscopy (XAS) at hard X-ray (incident X-ray energy higher than 5 keV) and soft X-ray (incident X-ray energy lower than 2 keV) regions to study the electrocatalysts’ chemical properties (oxidization state, electronic structure, and local structure), particularly in-situ/operando XAS to characterize the chemical properties change under the catalytic reaction conditions. Those findings revealed the structure-property and catalytic performance relationship. Two kinds of materials were chosen as the representative catalysts to build a systematic study. Perovskite LaCoO3, one of the transition metal oxides with moderate stability, has shown the approximate ORR and OER performance compared with standards. It was found that the electron number at the eg orbital can be the characteristic parameter to determine theactivity of this type of electrocatalyst. To verify and extend the theory, we substituted Co with Fe in LaCoO3 to tune the electronic structure, and subsequently changed not only the ORR activity but also selectivity. The soft XAS pointed out the metal-oxygen bonding hybridization and 3d transition metal electron distribution could further influence the catalytic performance in addition to metal d-band eg theory. Later, the LaCoO3 with co-substituted Fe and P was studied to confirm that the metal-oxygen bonding hybridization and electronic structure in the octahedral units would also influence the OER catalytic activity. In addition, the combination of hard and soft XAS further pointed out the hybridization between oxygen p-band and 3d transition metal eg orbit could be more critical than the general metal-oxygen hybridization for OER performance. The second material Co9S8, a representative material of transition metal X-ides that are unstable in reaction and experience restructuring throughout the reaction, has shown better OER performance than benchmark RuO2. The combination of operando hard XAS, operando Raman spectroscopy, and density of function theory suggested that the Co9S8 would completely restructure to form edge-sharing octahedral CoO6 units during OER, which is the truly active phase. The edge-sharing octahedral is hypothesized as the active center for restructuring-induced electrocatalysts, which was further verified by atomically dispersed Ir catalysts anchored on amorphous CoO for OER. The electronic structure of these catalyst materials can be altered to achieve the best OER activity by varying the composition of edge-sharing octahedral units. Through our comprehensive studies, we provide new approaches to develop high-performance ORR and OER electrocatalysts for accelerating the development of renewable energy systems

MetaDreamer: Efficient Text-to-3D Creation With Disentangling Geometry and Texture

Generative models for 3D object synthesis have seen significant advancements with the incorporation of prior knowledge distilled from 2D diffusion models. Nevertheless, challenges persist in the form of multi-view geometric inconsistencies and slow generation speeds within the existing 3D synthesis frameworks. This can be attributed to two factors: firstly, the deficiency of abundant geometric a priori knowledge in optimization, and secondly, the entanglement issue between geometry and texture in conventional 3D generation methods.In response, we introduce MetaDreammer, a two-stage optimization approach that leverages rich 2D and 3D prior knowledge. In the first stage, our emphasis is on optimizing the geometric representation to ensure multi-view consistency and accuracy of 3D objects. In the second stage, we concentrate on fine-tuning the geometry and optimizing the texture, thereby achieving a more refined 3D object. Through leveraging 2D and 3D prior knowledge in two stages, respectively, we effectively mitigate the interdependence between geometry and texture. MetaDreamer establishes clear optimization objectives for each stage, resulting in significant time savings in the 3D generation process. Ultimately, MetaDreamer can generate high-quality 3D objects based on textual prompts within 20 minutes, and to the best of our knowledge, it is the most efficient text-to-3D generation method. Furthermore, we introduce image control into the process, enhancing the controllability of 3D generation. Extensive empirical evidence confirms that our method is not only highly efficient but also achieves a quality level that is at the forefront of current state-of-the-art 3D generation techniques.Comment: arXiv admin note: text overlap with arXiv:2306.17843, arXiv:2209.14988 by other author

Sr3CrN3: a new electride with partially filled d-shells

Electrides are ionic crystals in which the electrons prefer to occupy free space, serving as anions. Because the electrons prefer to be in the pockets, channels, or layers to the atomic orbitals around the nuclei, it has been challenging to find electrides with partially filled d-shells, since an unoccupied d-shell provides an energetically favourable location for the electrons to occupy. We recently predicted the existence of electrides with partially filled d-shells using high-throughput computational screening. Here, we provide an experimental support using X-ray absorption spectroscopy and X-ray and neutron diffraction to show that Sr3CrN3 is indeed an electride despite its partial d-shell configuration. Our findings indicate that Sr3CrN3 is the first known electride with a partially filled d-shell, in agreement with theory, which significantly broadens the criteria for the search for new electride materials

On the Unusual Amber Coloration of Nanoporous Sol-gel Processed Al-doped Silica Glass: An Experimental Study

Silica is the most abundant component on the earth’s surface. It plays an important role in many natural processes. Silica is also a critical material for a wide range of technical applications such as in optics and electronics. In this work, we discuss our recent experimental observation of the unusual amber coloration of aluminum doped sol-gel glass that has not been reported in the past. We characterized Al-doped sol-gel glasses, prepared at different sintering temperature, using a plethora of techniques to investigate the origin of this unusual coloration and to understand their structural and chemical properties. We used these experimental results to test a number of possible coloring mechanisms. The results suggested this coloring is likely caused by temperature-dependent aluminum-associated defect centers associated with different amorphous-to-crystalline ratios of the annealed sol-gel silica glass structures

Coupling of Cell Surface Biotinylation and SILAC-Based Quantitative Proteomics Identified Myoferlin as a Potential Therapeutic Target for Nasopharyngeal Carcinoma Metastasis

Distant metastasis is a major cause of treatment failure in nasopharyngeal carcinoma (NPC) patients. Cell surface proteins represent attractive targets for cancer diagnosis or therapy. However, the cell surface proteins associated with NPC metastasis are poorly understood. To identify potential therapeutic targets for NPC metastasis, we isolated cell surface proteins from two isogenic NPC cell lines, 6-10B (low metastatic) and 5-8F (highly metastatic), through cell surface biotinylation. Stable isotope labeling by amino acids in cell culture (SILAC) based proteomics was applied to comprehensively characterize the cell surface proteins related with the metastatic phenotype. We identified 294 differentially expressed cell surface proteins, including the most upregulated protein myoferlin (MYOF), two receptor tyrosine kinases(RTKs) epidermal growth factor receptor (EGFR) and ephrin type-A receptor 2 (EPHA2) and several integrin family molecules. These differentially expressed proteins are enriched in multiple biological pathways such as the FAK-PI3K-mTOR pathway, focal adhesions, and integrin-mediated cell adhesion. The knockdown of MYOF effectively suppresses the proliferation, migration and invasion of NPC cells. Immunohistochemistry analysis also showed that MYOF is associated with NPC metastasis. We experimentally confirmed, for the first time, that MYOF can interact with EGFR and EPHA2. Moreover, MYOF knockdown could influence not only EGFR activity and its downstream epithelial–mesenchymal transition (EMT), but also EPHA2 ligand-independent activity. These findings suggest that MYOF might be an attractive potential therapeutic target that has double effects of simultaneously influencing EGFR and EPHA2 signaling pathway. In conclusion, this is the first study to profile the cell surface proteins associated with NPC metastasis and provide valuable resource for future researches

E3 ubiquitin ligases and deubiquitinases in bladder cancer tumorigenesis and implications for immunotherapies

With the rapidly increasing incidence of bladder cancer in China and worldwide, great efforts have been made to understand the detailed mechanism of bladder cancer tumorigenesis. Recently, the introduction of immune checkpoint inhibitor-based immunotherapy has changed the treatment strategy for bladder cancer, especially for advanced bladder cancer, and has improved the survival of patients. The ubiquitin–proteasome system, which affects many biological processes, plays an important role in bladder cancer. Several E3 ubiquitin ligases and deubiquitinases target immune checkpoints, either directly or indirectly. In this review, we summarize the recent progress in E3 ubiquitin ligases and deubiquitinases in bladder cancer tumorigenesis and further highlight the implications for bladder cancer immunotherapies

Al2O3 coated LiCoO2 as cathode for high-capacity and long-cycling Li-ion batteries

Lithium-ion batteries (LIBs) as energy storage devices play an important role in all aspects of our life. The increasing energy demand of the society requires LIBs with higher energy density and better performance. We here develop a new and easy-to-scaleup sol-gel method to coat a surface protection layer on commercial LiCoO2 cathode. We demonstrate that a proper thickness can improve the cycling life with a higher cut-off potential (4.5 V), larger energy capacity (180 mAh/g at 0.5C) and better energy density (35% more compared to non-coated LiCoO2). The mechanism of the protection layer is also revealed by a combination of electron microscopy and synchrotron X-ray spectroscopy. (C) 2018 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved

Comparative pharmacokinetics of polymyxin B in critically ill elderly patients with extensively drug-resistant gram-negative bacteria infections

Introduction: Elderly patients are more prone to develop acute kidney injury during infections and polymyxin B (PMB)-associated nephrotoxicity than young patients. The differential response to PMB between the elderly and young critically ill patients is unknown. We aimed to assess PMB exposure in elderly patients compared with young critically ill patients, and to determine the covariates of PMB pharmacokinetics in critically ill patients.Methods: Seventeen elderly patients (age ≥ 65 years) and six young critically ill patients (age < 65 years) were enrolled. Six to eight blood samples were collected during the 12 h intervals after at least six doses of intravenous PMB in each patient. PMB plasma concentrations were quantified by high-performance liquid chromatography-tandem mass spectrometry. The primary outcome was PMB exposure as assessed by the area under the concentration-time curve over 24 h at steady state (AUCss, 0–24 h).Results and Discussion: The elderly group had lower total body weight (TBW) and higher Charlson comorbidity scores than young group. Neither AUCss, 0–24 h nor normalized AUCss, 0–24 h (adjusting AUC for the daily dose in mg/kg of TBW) was significantly different between the elderly group and young group. The half-life time was longer in the elderly patients than in young patients (11.21 vs 6.56 h respectively, p = 0.003). Age and TBW were the covariates of half-life time (r = 0.415, p = 0.049 and r = −0.489, p = 0.018, respectively). TBW was the covariate of clearance (r = 0.527, p = 0.010) and AUCss, 0–24 h (r = −0.414, p = 0.049). Patients with AUCss, 0–24 h ≥ 100 mg·h/L had higher baseline serum creatinine levels and lower TBW than patients with AUCss, 0–24 h < 50 mg·h/L or patients with AUCss, 0–24 h 50–100 mg·h/L. The PMB exposures were comparable in elderly and young critically ill patients. High baseline serum creatinine levels and low TBW was associated with PMB overdose.Trial registration: ChiCTR2300073896 retrospectively registered on 25 July 2023

Chemical Composition, Antimicrobial and Insecticidal Activities of Essential Oils of Discarded Perfume Lemon and Leaves (Citrus Limon (L.) Burm. F.) as Possible Sources of Functional Botanical Agents

Two essential oils were isolated from discarded perfume lemon and leaves (Citrus limon (L.) Burm. F.) by hydro-distillation with good yield (0.044% for perfume lemon and 0.338% for leaves). Their biological activities were evaluated against five selected bacterial strains and Aedes albopictus (Ae. albopictus, Diptera: Culicidae). Chemical composition indicated that both essential oils were rich in essential phytochemicals including hydrocarbons, monoterpenes and sesquiterpene. These constituents revealed some variability among the oils displaying interesting chemotypes (R)-(+)-limonene (12.29–49.63%), citronellal (5.37–78.70%) and citronellol (2.98–7.18%). The biological assessments proved that the two essential oils had similar effect against bacterial (inhibition zones diameter ranging from 7.27 ± 0.06 to 10.37 ± 0.15 mm; MICs and MBCs ranging from 1.6 to 6.4 mg/mL); against Ae. albopictus larvae (LC(50) ranging from 384.81 to 395.09 ppm) and adult mosquito (LD(50) ranging from 133.059 to 218.962 μg/cm(2)); the activity of the two chemotypes ((R)-(+)-limonene and citronellal): larvae (LC(50) ranging from 267.08 to 295.28 ppm), which were all presented in dose-dependent manners. Through this work, we have showcased that recycling and reusing of agriculture by-products, such as discarded perfume lemon and leaves can produce eco-friendly alternatives in bacterial disinfectants and mosquito control product