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1.
J Cell Mol Med ; 28(3): e18094, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38214430

ABSTRACT

Lung cancer is a leading cause of cancer-related deaths worldwide. Recent studies have identified pyroptosis, a type of programmed cell death, as a critical process in the development and progression of lung cancer. In this study, we investigated the effect of EEBR, a new compound synthesized by our team, on pyroptosis in non-small cell lung cancer cells (NSCLC) and the underlying molecular mechanisms. Our results demonstrated that EEBR significantly reduced the proliferation and metastasis of NSCLC cells in vitro. Moreover, EEBR-induced pyroptosis in NSCLC cells, as evidenced by cell membrane rupture, the release of cytokines such as interleukin-18 and interleukin-1 beta and the promotion of Gasdermin D cleavage in a Caspase-1-dependent manner. Furthermore, EEBR promoted the nuclear translocation of NF-κB and upregulated the protein level of NLRP3. Subsequent studies revealed that EEBR-induced pyroptosis was suppressed by the inhibition of NF-κB. Finally, EEBR effectively suppressed the growth of lung cancer xenograft tumours by promoting NSCLC pyroptosis in animal models. Taken together, our findings suggest that EEBR induces Caspase-1-dependent pyroptosis through the NF-κB/NLRP3 signalling cascade in NSCLC, highlighting its potential as a candidate drug for NSCLC treatment.


Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Animals , Humans , NF-kappa B/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Carcinoma, Non-Small-Cell Lung/pathology , Pyroptosis , Caspase 1/metabolism , Inflammasomes/metabolism
2.
J Cell Mol Med ; 28(3): e18088, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38146591

ABSTRACT

Lysosomal dysfunction can drive carcinogenesis. Lysosomal-associated membrane protein 3 (LAMP3), is a member of the Lysosome Associated Membrane Proteins and is involved in the malignant phenotype such as tumour metastasis and drug resistance, while the mechanisms that regulate the malignant progression of tumour remain vague. Our study aims to provide a more systematic and comprehensive understanding of the role of LAMP3 in the progression of various cancers by various databases.We explored the role of LAMP3 in pan-cancer using The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database. Multiple online web platforms and software were used for data analysis, including HPA, TIMER, TISIDB, GEPIA, UALCAN, Kaplan-Meier plotter, DAVID and TIGER. The immunohistochemistry was used to quantify the LAMP3 and PD-L1 expression levels in cancer.High LAMP3 expression was found in most cancers and differentially expressed across molecular and immune subtypes. The expression of LAMP3 was involved in the immune-associated processes of Antigen processing and presentation, Th17 cell differentiation, Th1 and Th2 cell differentiation, and the immune-associated pathways of T cell receptor and B cell receptor signalling pathways in most cancers. It also correlated with genetic markers of immunomodulators in various cancers. LAMP3 and PD-L1 expression in BRCA and HNSC tissues was higher than that in corresponding adjacent normal tissues by immunohistochemistry. There is a significant correlation between the expression of LAMP3 and PD-L1.Our study elucidates that LAMP3 has different expression patterns and genetic alteration patterns in different tumours. It is a potential biomarker for immune-related cancer diagnosis, prognosis and efficacy prediction.


Subject(s)
B7-H1 Antigen , Neoplasms , Humans , Lysosomal-Associated Membrane Protein 3 , Prognosis , Lysosomal Membrane Proteins
3.
Biomed Pharmacother ; 168: 115797, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37913735

ABSTRACT

Triple negative breast cancer (TNBC) presents a formidable challenge due to the lack of effective treatment modalities. Immunotherapy stands as a promising therapeutic approach; however, the emergence of drug resistance mechanisms within tumor cells, particularly those targeting apoptosis and pyroptosis, has hampered its clinical efficacy. SHP2 is intricately involved in diverse physiological processes, including immune cell proliferation, infiltration, and tumor progression. Nevertheless, the precise contribution of SHP2 to tumor cell pyroptosis resistance remains inadequately understood. Herein, we demonstrate that SHP2 inhibition hampers the proliferative, migratory, and invasive capabilities of TNBC, accompanied by noticeable alterations in cellular membrane architecture. Mechanistically, we provide evidence that SHP2 depletion triggers the activation of Caspase-1 and GSDMD, resulting in GSDMD-dependent release of LDH, IL-1ß, and IL-18. Furthermore, computational analyses and co-localization investigations substantiate the hypothesis that SHP2 may hinder pyroptosis through direct binding to JNK, thereby impeding JNK phosphorylation. Our cellular experiments further corroborate these findings by demonstrating that JNK inhibition rescues pyroptosis induced by SHP2 knockdown. Strikingly, in vivo experiments validate the suppressive impact of SHP2 knockdown on tumor progression via enhanced JNK phosphorylation. Additionally, SHP2 knockdown augments tumor sensitivity to anti-PD-1 therapy, thus reinforcing the pro-pyroptotic effects and inhibiting tumor growth. In summary, our findings elucidate the mechanism by which SHP2 governs TNBC pyroptosis, underscoring the potential of SHP2 inhibition to suppress cell pyroptosis resistance and its utility as an adjunctive agent for tumor immunotherapy.


Subject(s)
Immune Checkpoint Inhibitors , Protein Tyrosine Phosphatase, Non-Receptor Type 11 , Pyroptosis , Triple Negative Breast Neoplasms , Humans , Caspase 1 , Immune Checkpoint Inhibitors/therapeutic use , Phosphorylation , Protein Tyrosine Phosphatase, Non-Receptor Type 11/metabolism , Triple Negative Breast Neoplasms/drug therapy
4.
Cancer Cell Int ; 23(1): 285, 2023 Nov 20.
Article in English | MEDLINE | ID: mdl-37986192

ABSTRACT

BACKGROUND: TSTA3 gene encoding GDP-L-fucose synthase has recently been proved to be closely related to the prognosis of patients with various tumors. However, its role in lung cancer is still unclear. The purpose of this study is to explore the expression level, prognostic effect, potential function and mechanism of TSTA3 in lung cancer. METHODS: Based on TCGA database, Kaplan-Meier and COX regression was used to analyze the relationship between TSTA3 expression and prognosis of lung cancer patients. Immunohistochemistry was used to determine the TSTA3 protein expression in lung cancer and normal tissues. The function of TSTA3 in lung squamous cell carcinoma (LUSC) cell was determined by CCK8, colony formation, transwell assay in vitro and subcutaneous xenografts in vivo. Transcriptome analysis, Lyso-Tracker Red staining and rescue experiment were used to explore the possible underlying mechanism. RESULTS: The expression of TSTA3 was significantly increased in lung cancer, especially in LUSC, and was significantly correlated with the malignant characteristics of LUSC. COX regression analysis showed that the high expression of TSTA3 was an independent prognostic factor in LUSC patients. This was also confirmed by immunohistochemical staining. Compared with the control group, the proliferation, colony formation, invasion and migration ability of LUSC cells with TSTA3 overexpression was enhanced. Similarly, the ability of cell proliferation, colony formation, invasion and migration were weakened after transient knockdown of TSTA3. In vivo experiment showed that compared with control group, TSTA3 overexpression significantly promoted the growth of tumor and shortened survival time. In addition, transcriptome sequencing analysis showed that the differentially expressed genes between TSTA3 overexpression and control group was mainly concentrated in the lysosome pathway. Further study found that TSTA3 might affect the proliferation, invasion and migration of LUSC by regulating the expression of lysosome-associated membrane protein 2 (LAMP2) in LUSC. CONCLUSION: The expression level of TSTA3 in LUSC is significantly higher than that in normal tissues. High expression of TSTA3 is associated with poor prognosis of LUSC patients. TSTA3 may affect the proliferation, invasion and migration of LUSC by regulating LAMP2.

5.
Nat Commun ; 14(1): 3231, 2023 Jun 03.
Article in English | MEDLINE | ID: mdl-37270627

ABSTRACT

Smart window is an attractive option for efficient heat management to minimize energy consumption and improve indoor living comfort owing to their optical properties of adjusting sunlight. To effectively improve the sunlight modulation and heat management capability of smart windows, here, we propose a co-assembly strategy to fabricate the electrochromic and thermochromic smart windows with tunable components and ordered structures for the dynamic regulation of solar radiation. Firstly, to enhance both illumination and cooling efficiency in electrochromic windows, the aspect ratio and mixed type of Au nanorods are tuned to selectively absorb the near-infrared wavelength range of 760 to 1360 nm. Furthermore, when assembled with electrochromic W18O49 nanowires in the colored state, the Au nanorods exhibit a synergistic effect, resulting in a 90% reduction of near-infrared light and a corresponding 5 °C cooling effect under 1-sun irradiation. Secondly, to extend the fixed response temperature value to a wider range of 30-50 °C in thermochromic windows, the doping amount and mixed type of W-VO2 nanowires are carefully regulated. Last but not the least, the ordered assembly structure of the nanowires can greatly reduce the level of haze and enhance visibility in the windows.

6.
Curr Pharm Des ; 29(12): 940-946, 2023.
Article in English | MEDLINE | ID: mdl-37005539

ABSTRACT

BACKGROUND: Colorectal cancer (CRC) is the most common type of gastrointestinal tumor, but the available pharmacological treatment is insufficient. As a traditional Chinese medicine, the green walnut husks (QLY) exhibit anti-inflammatory, analgesic, anti-bacterial and anti-tumor effects. However, the effects and molecular mechanisms of QLY extracts on CRC were not yet made known. OBJECTIVE: This study aims to provide efficient and low toxicity drugs for the treatment of CRC. The purpose of this study is to explore the anti-CRC effect and mechanism of QLY, providing preliminary data support for clinical research of QLY. METHODS: Western blotting, Flow cytometry, immunofluorescence, Transwell, MTT, Cell proliferation assay, and xenograft model were used to perform the research. RESULTS: In this study, the potential of QLY to inhibit the proliferation, migration invasion and induce apoptosis of the mouse colorectal cancer cell line CT26 in vitro was identified. The xenograft tumor model of CRC noted that QLY suppressed tumor growth without sacrificing body weight in mice. In addition, QLY-induced apoptosis in tumor cells through NLRC3/PI3K/AKT signaling pathway was revealed. CONCLUSION: QLY regulates the levels of mTOR, Bcl-2 and Bax by affecting the NLRC3/PI3K/AKT pathway to promote apoptosis of tumor cells, suppressing cell proliferation, invasion and migration, and subsequently preventing the progression of colon cancer.


Subject(s)
Colorectal Neoplasms , Juglans , Humans , Animals , Mice , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Colorectal Neoplasms/metabolism , Apoptosis , Cell Proliferation , Cell Line, Tumor , Cell Movement , Intercellular Signaling Peptides and Proteins/therapeutic use
7.
Front Immunol ; 14: 1134636, 2023.
Article in English | MEDLINE | ID: mdl-37063879

ABSTRACT

ILC3s have been identified as crucial immune regulators that play a role in maintaining host homeostasis and modulating the antitumor response. Emerging evidence supports the idea that LTi cells play an important role in initiating lymphoid tissue development, while other ILC3s can promote host defense and orchestrate adaptive immunity, mainly through the secretion of specific cytokines and crosstalk with other immune cells or tissues. Additionally, dysregulation of ILC3-mediated overexpression of cytokines, changes in subset abundance, and conversion toward other ILC subsets are closely linked with the occurrence of tumors and inflammatory diseases. Regulation of ILC3 cytokines, ILC conversion and LTi-induced TLSs may be a novel strategy for treating tumors and intestinal or extraintestinal inflammatory diseases. Herein, we discuss the development of ILCs, the biology of ILC3s, ILC plasticity, the correlation of ILC3s and adaptive immunity, crosstalk with the intestinal microenvironment, controversial roles of ILC3s in intestinal diseases and potential applications for treatment.


Subject(s)
Intestinal Diseases , Neoplasms , Humans , Lymphocytes , Immunity, Innate , Cytokines , Immunotherapy , Tumor Microenvironment
8.
Adv Mater ; 35(19): e2211603, 2023 May.
Article in English | MEDLINE | ID: mdl-36802104

ABSTRACT

The past decade has witnessed the development of layered-hydroxide-based self-supporting electrodes, but the low active mass ratio impedes its all-around energy-storage applications. Herein, the intrinsic limit of layered hydroxides is broken by engineering F-substituted ß-Ni(OH)2 (Ni-F-OH) plates with a sub-micrometer thickness (over 700 nm), producing a superhigh mass loading of 29.8 mg cm-2 on the carbon substrate. Theoretical calculation and X-ray absorption spectroscopy analysis demonstrate that Ni-F-OH shares the ß-Ni(OH)2 -like structure with slightly tuned lattice parameters. More interestingly, the synergy modulation of NH4 + and F- is found to serve as the key enabler to tailor these sub-micrometer-thickness 2D plates thanks to the modification effects on the (001) plane surface energy and local OH- concentration. Guided by this mechanism, the superstructures of bimetallic hydroxides and their derivatives are further developed, revealing they are a versatile family with great promise. The tailored ultrathick phosphide superstructure achieves a superhigh specific capacity of 7144 mC cm-2 and a superior rate capability (79% at 50 mA cm-2 ). This work highlights a multiscale understanding of how exceptional structure modulation happens in low-dimensional layered materials. The as-built unique methodology and mechanisms will boost the development of advanced materials to better meet future energy demands.

9.
Angew Chem Int Ed Engl ; 62(15): e202218664, 2023 Apr 03.
Article in English | MEDLINE | ID: mdl-36787047

ABSTRACT

Using sunlight to produce valuable chemicals and fuels from carbon dioxide (CO2 ), i.e., artificial photosynthesis (AP) is a promising strategy to achieve solar energy storage and a negative carbon cycle. However, selective synthesis of C2 compounds with a high CO2 conversion rate remains challenging for current AP technologies. We performed CO2 photoelectroreduction over a graphene/silicon carbide (SiC) catalyst under simulated solar irradiation with ethanol (C2 H5 OH) selectivity of>99 % and a CO2 conversion rate of up to 17.1 mmol gcat -1 h-1 with sustained performance. Experimental and theoretical investigations indicated an optimal interfacial layer to facilitate the transfer of photogenerated electrons from the SiC substrate to the few-layer graphene overlayer, which also favored an efficient CO2 to C2 H5 OH conversion pathway.

10.
ACS Appl Mater Interfaces ; 15(5): 7518-7528, 2023 Feb 08.
Article in English | MEDLINE | ID: mdl-36715357

ABSTRACT

Charge transfer across the electrode-electrolyte interface is a highly complex and convoluted process involving diverse solvated species with varying structures and compositions. Despite recent advances in in situ and operando interfacial analysis, molecular specific reactivity of solvated species is inaccessible due to a lack of precise control over the interfacial constituents and/or an unclear understanding of their spectroscopic fingerprints. However, such molecular-specific understanding is critical to the rational design of energy-efficient solid-electrolyte interphase layers. We have employed ion soft landing, a versatile and highly controlled method, to prepare well-defined interfaces assembled with selected ions, either as solvated species or as bare ions, with distinguishing molecular precision. Equipped with precise control over interfacial composition, we employed in situ multimodal spectroscopic characterization to unravel the molecular specific reactivity of Mg solvated species comprising (i.e., bis(trifluoromethanesulfonyl)imide, TFSI-) anions and solvent molecules (i.e., dimethoxyethane, DME/G1) on a Mg metal surface relevant to multivalent Mg batteries. In situ multimodal spectroscopic characterization revealed higher reactivity of the undercoordinated solvated species [Mg-TFSI-G1]+ compared to the fully coordinated [Mg-TFSI-(G1)2]+ species or even the bare TFSI-. These results were corroborated by the computed reaction pathways and energy barriers for decomposition of the TFSI- within Mg solvated species relative to bare TFSI-. Finally, we evaluated the TFSI reactivity under electrochemical conditions using Mg(TFSI)2-DME-based phase-separated electrolytes representing different solvated constituents. Based on our multimodal study, we report a detailed understanding of TFSI- decomposition processes as part of coordinated solvated species at a Mg-metal anode that will aid the rational design of improved sustainable electrochemical energy technologies.

11.
Proc Natl Acad Sci U S A ; 120(1): e2206850120, 2023 01 03.
Article in English | MEDLINE | ID: mdl-36577066

ABSTRACT

Atomically dispersed catalysts have been shown highly active for preferential oxidation of carbon monoxide in the presence of excess hydrogen (PROX). However, their stability has been less than ideal. We show here that the introduction of a structural component to minimize diffusion of the active metal center can greatly improve the stability without compromising the activity. Using an Ir dinuclear heterogeneous catalyst (DHC) as a study platform, we identify two types of oxygen species, interfacial and bridge, that work in concert to enable both activity and stability. The work sheds important light on the synergistic effect between the active metal center and the supporting substrate and may find broad applications for the use of atomically dispersed catalysts.


Subject(s)
Carbon Monoxide , Hydrogen , Carbon Monoxide/chemistry , Oxidation-Reduction , Catalysis , Hydrogen/chemistry , Platinum/chemistry
12.
ACS Appl Mater Interfaces ; 14(15): 17570-17577, 2022 Apr 20.
Article in English | MEDLINE | ID: mdl-35390250

ABSTRACT

Rechargeable aqueous zinc-ion batteries (AZIBs) are close complements to lithium-ion batteries for next-generation grid-scale applications owing to their high specific capacity, low cost, and intrinsic safety. Nevertheless, the viable cathode materials (especially manganese oxides) of AZIBs suffer from poor conductivity and inferior structural stability upon cycling, thereby impeding their practical applications. Herein, a facile synthetic strategy of bead-like manganese oxide coated with carbon nanofibers (MnOx-CNFs) based on electrospinning is reported, which can effectively improve the electron/ion diffusion kinetics and provide robust structural stability. These benefits of MnOx-CNFs are evident in the electrochemical performance metrics, with a long cycling durability (i.e., a capacity retention of 90.6% after 2000 cycles and 71% after 5000 cycles) and an excellent rate capability. Furthermore, the simultaneous insertion of H+/Zn2+ and the Mn redox process at the surface and in the bulk of MnOx-CNFs are clarified in detail. Our present study not only provides a simple avenue for synthesizing high-performance Mn-based cathode materials but also offers unique knowledge on understanding the corresponding electrochemical reaction mechanism for AZIBs.

13.
Adv Mater ; 34(20): e2201152, 2022 May.
Article in English | MEDLINE | ID: mdl-35315130

ABSTRACT

Utilizing reversible lattice oxygen redox (OR) in battery electrodes is an essential strategy to overcome the capacity limitation set by conventional transition metal redox. However, lattice OR reactions are often accompanied with irreversible oxygen oxidation, leading to local structural transformations and voltage/capacity fading. Herein, it is proposed that the reversibility of lattice OR can be remarkably improved through modulating transition metal-oxygen covalency for layered electrode of Na-ion batteries. By developing a novel layered P2-Na0.6 Mg0.15 Mn0.7 Cu0.15 O2 electrode, it is demonstrated that the highly electronegative Cu dopants can improve the lattice OR reversibility to 95% compared to 73% for Cu-free counterpart, as directly quantified through high-efficiency mapping of resonant inelastic X-ray scattering. Crucially, the large energetic overlap between Cu 3d and O 2p states dictates the rigidity of oxygen framework, which effectively mitigates the structural distortion of local oxygen environment upon (de)sodiation and leads to the enhanced lattice OR reversibility. The electrode also exhibits a completely solid-solution reaction with an ultralow volume change of only 0.45% and a reversible metal migration upon cycling, which together ensure the improved electrochemical performance. These results emphasize the critical role of transition metal-oxygen covalency for enhancing the reversibility of lattice OR toward high-capacity electrodes employing OR chemistry.

14.
Small Methods ; 6(3): e2101524, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35084117

ABSTRACT

Sodium-ion batteries (SIBs) have attracted widespread attention for large-scale energy storage, but one major drawback, i.e., the limited capacity of cathode materials, impedes their practical applications. Oxygen redox reactions in layered oxide cathodes are proven to contribute additionally high specific capacity, while such cathodes often suffer from irreversible structural transitions, causing serious capacity fading and voltage decay upon cycling, and the formation process of the oxidized oxygen species remains elusive. Herein, a series of Al-doped P2-type Na0.6 Ni0.3 Mn0.7 O2 cathode materials for SIBs are reported and the corresponding charge compensation mechanisms are investigated qualitatively and quantitatively. The combined analyses reveal that Al doping boosts the reversible oxygen redox reactions through the reductive coupling reactions between orphaned O 2p states in NaOAl local configurations and Ni4+ ions, as directly evidenced by X-ray absorption fine structure results. Additionally, Al doping also induces an increased interlayer spacing and inhibits the unfavorable P2 to O2 phase transition upon desodiation/sodiation, which is common in P2-type Mn-based cathode materials, leading to the great improvement in capacity retention and rate capability. This work provides deeper insights into the development of structurally stable and high-capacity layered cathode materials for SIBs with anion-cation synergetic contributions.

15.
J Am Chem Soc ; 143(40): 16538-16548, 2021 10 13.
Article in English | MEDLINE | ID: mdl-34524811

ABSTRACT

Nanoscale zerovalent iron (nZVI) is considered as a highly efficient material for sequestrating arsenite, but the origin of its high efficacy as well as the chemical transformations of arsenite during reaction is not well understood. Here, we report an in situ X-ray absorption spectroscopy (XAS) study to investigate the complex mechanism of nZVI reaction with arsenite under anaerobic conditions at the time scale from seconds to days. The time-resolved XAS analysis revealed a gradual oxidation of AsIII to AsV in the course of minutes to hours in both the solid and liquid phase for the high (above 0.5 g/L) nZVI dose system. When the reaction time increased up to 60 days, AsV became the dominant species. The quick-scanning extended X-ray absorption fine structure (QEAXFS) was introduced to discover the transient intermediate at the highly reactive stage, and a small red-shift in As K-edge absorption edge was observed. The QEAXFS combined with density functional theory (DFT) calculation suggested that the red-shift is likely due to the electron donation in a Fe-O-As complex and possible active sites of As sequestrations include Fe(OH)4 and 4-Fe cluster. This is the first time that the transient reaction intermediate was identified in the As-nZVI sequestration system at the fast-reacting early stage. This study also demonstrated usefulness of in situ monitoring techniques in environmental water research.


Subject(s)
Arsenites
16.
Nano Lett ; 21(9): 3981-3988, 2021 May 12.
Article in English | MEDLINE | ID: mdl-33886344

ABSTRACT

The recent proposal of antidoping scheme breaks new ground in conceiving conversely functional materials and devices; yet, the few available examples belong to the correlated electron systems. Here, we demonstrate both theoretically and experimentally that the main group oxide BaBiO3 is a model system for antidoping using oxygen vacancies. The first-principles calculations show that the band gap systematically increases due to the strongly enhanced Bi-O breathing distortions away from the vacancies and the annihilation of Bi 6s/O 2p hybridized conduction bands near the vacancies. Our further spectroscopic experiments confirm that the band gap increases systematically with electron doping, with a maximal gap enhancement of ∼75% when the film's stoichiometry is reduced to BaBiO2.75. These results unambiguously demonstrate the remarkable antidoping effect in a material without strong electron correlations and underscores the importance of bond disproportionation in realizing such an effect.

17.
Phys Rev Lett ; 125(11): 116401, 2020 Sep 11.
Article in English | MEDLINE | ID: mdl-32975957

ABSTRACT

The exciton-phonon coupling in highly oriented pyrolytic graphite is studied using resonant inelastic x-ray scattering (RIXS) spectroscopy. With ∼70 meV energy resolution, multiple low energy excitations associated with coupling to phonons can be clearly resolved in the RIXS spectra. Using resonance dependence and the closed form for RIXS cross section without considering the intermediate state mixing of phonon modes, the dimensionless coupling constant g is determined to be 5 and 0.35, corresponding to the coupling strength of 0.42 eV+/-20 meV and 0.20 eV+/-20 meV, for zone center and boundary phonons, respectively. The reduced g value for the zone-boundary phonon may be related to its double resonance nature.

18.
J Synchrotron Radiat ; 27(Pt 3): 695-707, 2020 May 01.
Article in English | MEDLINE | ID: mdl-32381770

ABSTRACT

The optical design of a Hettrick-Underwood-style soft X-ray spectrometer with Wolter type 1 mirrors is presented. The spectrometer with a nominal length of 3.1 m can achieve a high resolving power (resolving power higher than 10000) in the soft X-ray regime when a small source beam (<3 µm in the grating dispersion direction) and small pixel detector (5 µm effective pixel size) are used. Adding Wolter mirrors to the spectrometer before its dispersive elements can realize the spatial imaging capability, which finds applications in the spectroscopic studies of spatially dependent electronic structures in tandem catalysts, heterostructures, etc. In the pump-probe experiments where the pump beam perturbs the materials followed by the time-delayed probe beam to reveal the transient evolution of electronic structures, the imaging capability of the Wolter mirrors can offer the pixel-equivalent femtosecond time delay between the pump and probe beams when their wavefronts are not collinear. In combination with some special sample handing systems, such as liquid jets and droplets, the imaging capability can also be used to study the time-dependent electronic structure of chemical transformation spanning multiple time domains from microseconds to nanoseconds. The proposed Wolter mirrors can also be adopted to the existing soft X-ray spectrometers that use the Hettrick-Underwood optical scheme, expanding their capabilities in materials research.

19.
J Phys Chem B ; 124(16): 3408-3417, 2020 04 23.
Article in English | MEDLINE | ID: mdl-32223137

ABSTRACT

Although the crystal structures for many inorganic compounds are readily available, researchers are still working hard to understand the relations between the structures and chemical properties of solutions because most of the chemical reactions take place in solutions. A huge amount of effort has been put toward modeling the ion solvation structure from the perspectives of both experiments and theories. In this study, the solvation structures of Ca2+ ions in aqueous and alcoholic solutions at different concentrations were carefully evaluated by Ca K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses. Density functional theory (DFT) calculations were also performed to correlate the results with the experimental data and then further extended to other similar systems. It was found that the number of coordinating solvent molecules decreases with increasing Ca2+ concentration and increasing solvent molecule sizes. From the EXAFS data, it was observed that the first solvation shell of Ca2+ splits into two Ca-O distances in a methanol solution and the counter ion Cl- might also be within the first shell at high concentrations. For the first time, the effects of solvents with different polarities and sizes on the ion solvation environment were systematically evaluated.

20.
RSC Adv ; 10(46): 27315-27321, 2020 Jul 21.
Article in English | MEDLINE | ID: mdl-35516916

ABSTRACT

The solvation shell structures of Ca2+ in aqueous and organic solutions probed by calcium L-edge soft X-ray absorption spectroscopy (XAS) and DFT/MD simulations show the coordination number of Ca2+ to be negatively correlated with the electrolyte concentration and the steric hindrance of the solvent molecule. In this work, the calcium L-edge soft XAS demonstrates its sensitivity to the surrounding chemical environment. Additionally, the total electron yield (TEY) mode is surface sensitive because the electron penetration depth is limited to a few nanometers. Thus this study shows its implications for future battery studies, especially for probing the electrolyte/electrode interface for electrochemical reactions under in situ/operando conditions.

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