Multiple Signaling Roles of CD3ε and Its Application in CAR-T Cell Therapy.

A T cell receptor (TCR) mediates antigen-induced signaling through its associated CD3ε, δ, γ, and ζ, but the contributions of different CD3 chains remain elusive. Using quantitative mass spectrometry, we simultaneously quantitated the phosphorylation of the immunoreceptor tyrosine-based activation motif (ITAM) of all CD3 chains upon TCR stimulation. A subpopulation of CD3ε ITAMs was mono-phosphorylated, owing to Lck kinase selectivity, and specifically recruited the inhibitory Csk kinase to attenuate TCR signaling, suggesting that TCR is a self-restrained signaling machinery containing both activating and inhibitory motifs. Moreover, we found that incorporation of the CD3ε cytoplasmic domain into a second-generation chimeric antigen receptor (CAR) improved antitumor activity of CAR-T cells. Mechanistically, the Csk-recruiting ITAM of CD3ε reduced CAR-T cytokine production whereas the basic residue rich sequence (BRS) of CD3ε promoted CAR-T persistence via p85 recruitment. Collectively, CD3ε is a built-in multifunctional signal tuner, and increasing CD3 diversity represents a strategy to design next-generation CAR.

Physiological temperature drives TRPM4 ligand recognition and gating.

Temperature profoundly affects macromolecular function, particularly in proteins with temperature sensitivity1,2. However, its impact is often overlooked in biophysical studies that are typically performed at non-physiological temperatures, potentially leading to inaccurate mechanistic and pharmacological insights. Here we demonstrate temperature-dependent changes in the structure and function of TRPM4, a temperature-sensitive Ca2+-activated ion channel3-7. By studying TRPM4 prepared at physiological temperature using single-particle cryo-electron microscopy, we identified a 'warm' conformation that is distinct from those observed at lower temperatures. This conformation is driven by a temperature-dependent Ca2+-binding site in the intracellular domain, and is essential for TRPM4 function in physiological contexts. We demonstrated that ligands, exemplified by decavanadate (a positive modulator)8 and ATP (an inhibitor)9, bind to different locations of TRPM4 at physiological temperatures than at lower temperatures10,11, and that these sites have bona fide functional relevance. We elucidated the TRPM4 gating mechanism by capturing structural snapshots of its different functional states at physiological temperatures, revealing the channel opening that is not observed at lower temperatures. Our study provides an example of temperature-dependent ligand recognition and modulation of an ion channel, underscoring the importance of studying macromolecules at physiological temperatures. It also provides a potential molecular framework for deciphering how thermosensitive TRPM channels perceive temperature changes.

Structural basis of lipopolysaccharide extraction by the LptB2FGC complex.

In Gram-negative bacteria, lipopolysaccharide is essential for outer membrane formation and antibiotic resistance. The seven lipopolysaccharide transport (Lpt) proteins A-G move lipopolysaccharide from the inner to the outer membrane. The ATP-binding cassette transporter LptB2FG, which tightly associates with LptC, extracts lipopolysaccharide out of the inner membrane. The mechanism of the LptB2FG-LptC complex (LptB2FGC) and the role of LptC in lipopolysaccharide transport are poorly understood. Here we characterize the structures of LptB2FG and LptB2FGC in nucleotide-free and vanadate-trapped states, using single-particle cryo-electron microscopy. These structures resolve the bound lipopolysaccharide, reveal transporter-lipopolysaccharide interactions with side-chain details and uncover how the capture and extrusion of lipopolysaccharide are coupled to conformational rearrangements of LptB2FGC. LptC inserts its transmembrane helix between the two transmembrane domains of LptB2FG, which represents a previously unknown regulatory mechanism for ATP-binding cassette transporters. Our results suggest a role for LptC in achieving efficient lipopolysaccharide transport, by coordinating the action of LptB2FG in the inner membrane and Lpt protein interactions in the periplasm.

Conformation space of a heterodimeric ABC exporter under turnover conditions.

Cryo-electron microscopy (cryo-EM) has the capacity to capture molecular machines in action1-3. ATP-binding cassette (ABC) exporters are highly dynamic membrane proteins that extrude a wide range of substances from the cytosol4-6 and thereby contribute to essential cellular processes, adaptive immunity and multidrug resistance7,8. Despite their importance, the coupling of nucleotide binding, hydrolysis and release to the conformational dynamics of these proteins remains poorly resolved, especially for heterodimeric and/or asymmetric ABC exporters that are abundant in humans. Here we present eight high-resolution cryo-EM structures that delineate the full functional cycle of an asymmetric ABC exporter in a lipid environment. Cryo-EM analysis under active turnover conditions reveals distinct inward-facing (IF) conformations-one of them with a bound peptide substrate-and previously undescribed asymmetric post-hydrolysis states with dimerized nucleotide-binding domains and a closed extracellular gate. By decreasing the rate of ATP hydrolysis, we could capture an outward-facing (OF) open conformation-an otherwise transient state vulnerable to substrate re-entry. The ATP-bound pre-hydrolysis and vanadate-trapped states are conformationally equivalent; both comprise co-existing OF conformations with open and closed extracellular gates. By contrast, the post-hydrolysis states from the turnover experiment exhibit asymmetric ATP and ADP occlusion after phosphate release from the canonical site and display a progressive separation of the nucleotide-binding domains and unlocking of the intracellular gate. Our findings reveal that phosphate release, not ATP hydrolysis, triggers the return of the exporter to the IF conformation. By mapping the conformational landscape during active turnover, aided by mutational and chemical modulation of kinetic rates to trap the key intermediates, we resolved fundamental steps of the substrate translocation cycle of asymmetric ABC transporters.

Interaction of gallium, indium, and vanadyl curcumin complexes with hen egg-white lysozyme (HEWL): Mechanistic aspects and evaluation of antiamyloidogenic activity.

Many proteins and peptides can aggregate into amyloid fibrils with high-ordered and cross-ß rich structure characteristics. Amyloid deposition is a common feature of neurodegenerative diseases called amyloidosis. Various natural polyphenolic compounds such as curcumin exhibited antiamyloidogenic activities, but less researches were focused on the metal complexes of these compounds. In this study, the inhibitory effects of gallium curcumin (Ga(cur)3), indium curcumin (In(cur)3), and vanadyl curcumin (VO(cur)2) on the amyloid fibrillation of hen egg white lysozyme (HEWL) have been investigated. Moreover, the details of binding interactions of these metal complexes with HEWL have been explored. The results of fluorescence quenching analyses revealed that In(cur)3 and VO(cur)2 have much higher binding affinities than Ga(cur)3 toward HEWL. The interactions of these metal complexes were accompanied by partial conformational changes in the tertiary structure of HEWL. The kinetic curves of the fibrillation process demonstrated that In(cur)3 and VO(cur)2 have higher inhibitory effects than Ga(cur)3 on the amyloid fibrillation of HEWL. The strength of binding to HEWL is completely in accordance with inhibitory activities of these metal complexes of curcumin.

Facet-Dependent Fe2O3/BiVO4(110)/BiVO4(010)/Fe2O3 Dual S-Scheme Photocatalyst as an Efficient Visible-Light-Driven Peroxymonosulfate Activator for Norfloxacin Degradation.

A lack of eco-friendly, highly active photocatalyst for peroxymonosulfate (PMS) activation and unclear environmental risks are significant challenges. Herein, we developed a double S-scheme Fe2O3/BiVO4(110)/BiVO4(010)/Fe2O3 photocatalyst to activate PMS and investigated its impact on wheat seed germination. We observed an improvement in charge separation by depositing Fe2O3 on the (010) and (110) surfaces of BiVO4. This enhancement is attributed to the formation of a dual S-scheme charge transfer mechanism at the interfaces of Fe2O3/BiVO4(110) and BiVO4(010)/Fe2O3. By introducing PMS into the system, photogenerated electrons effectively activate PMS, generating reactive oxygen species (ROS) such as hydroxyl radicals (·OH) and sulfate radicals (SO4·-). Among the tested systems, the 20% Fe2O3/BiVO4/Vis/PMS system exhibits the highest catalytic efficiency for norfloxacin (NOR) removal, reaching 95% in 40 min. This is twice the catalytic efficiency of the Fe2O3/BiVO4/PMS system, 1.8 times that of the Fe2O3/BiVO4 system, and 5 times that of the BiVO4 system. Seed germination experiments revealed that Fe2O3/BiVO4 heterojunction was beneficial for wheat seed germination, while PMS had a significant negative effect. This study provides valuable insights into the development of efficient and sustainable photocatalytic systems for the removal of organic pollutants from wastewater.

How Do Differences in Electronic Structure Affect the Use of Vanadium Intermediates as Mimics in Nonheme Iron Hydroxylases?

We study active-site models of nonheme iron hydroxylases and their vanadium-based mimics using density functional theory to determine if vanadyl is a faithful structural mimic. We identify crucial structural and energetic differences between ferryl and vanadyl isomers owing to the differences in their ground electronic states, i.e., high spin (HS) for Fe and low spin (LS) for V. For the succinate cofactor bound to the ferryl intermediate, we predict facile interconversion between monodentate and bidentate coordination isomers for ferryl species but difficult rearrangement for vanadyl mimics. We study isomerization of the oxo intermediate between axial and equatorial positions and find the ferryl potential energy surface to be characterized by a large barrier of ca. 10 kcal/mol that is completely absent for the vanadyl mimic. This analysis reveals even starker contrasts between Fe and V in hydroxylases than those observed for this metal substitution in nonheme halogenases. Analysis of the relative bond strengths of coordinating carboxylate ligands for Fe and V reveals that all of the ligands show stronger binding to V than Fe owing to the LS ground state of V in contrast to the HS ground state of Fe, highlighting the limitations of vanadyl mimics of native nonheme iron hydroxylases.

Open-Framework Vanadate as Efficient Ion Exchanger for Uranyl Removal.

The elimination of uranium from radioactive wastewater is crucial for the safe management and operation of environmental remediation. Here, we present a layered vanadate with high acid/base stability, [Me2NH2]V3O7, as an excellent ion exchanger capturing uranyl from highly complex aqueous solutions. The material possesses an indirect band gap, ferromagnetic characteristic and a flower-like morphology comprising parallel nanosheets. The layered structure of [Me2NH2]V3O7 is predominantly upheld by the H-bond interaction between anionic framework [V3O7]nn- and intercalated [Me2NH2]+. The [Me2NH2]+ within [Me2NH2]V3O7 can be readily exchanged with UO22+. [Me2NH2]V3O7 exhibits high exchange capacity (qm = 176.19 mg/g), fast kinetics (within 15 min), high removal efficiencies (>99%), and good selectivity against an excess of interfering ions. It also displays activity for UO22+ ion exchange over a wide pH range (2.00-7.12). More importantly, [Me2NH2]V3O7 has the capability to effectively remove low-concentration uranium, yielding a residual U concentration of 13 ppb, which falls below the EPA-defined acceptable limit of 30 ppb in typical drinking water. [Me2NH2]V3O7 can also efficiently separate UO22+ from Cs+ or Sr2+ achieving the highest separation factors (SFU/Cs of 589 and SFU/Sr of 227) to date. The BOMD and DFT calculations reveal that the driving force of ion exchange is dominated by the interaction between UO22+ and [V3O7]nn-, whereas the ion exchange rate is influenced by the mobility of UO22+ and [Me2NH2]+. Our experimental findings indicate that [Me2NH2]V3O7 can be considered as a promising uranium scavenger for environmental remediation. Additionally, the simulation results provide valuable mechanistic interpretations for ion exchange and serve as a reference for designing novel ion exchangers.

Novel vanadyl complexes synthesis, characterization and interactions with bovine serum albumin-effects on STZ- diabetes rats.

Drug-protein interactions are essential since most administered drugs bind abundantly and reversibly to serum albumin and are delivered mainly as a complex with protein. The nature and strength of drug-protein interactions have a big impact on how a drug works biologically. The binding parameters are useful in studying the pharmacological response of drugs and the designing of dosage forms. Serum albumin is regarded as optimal model for in vitro research on drug-protein interaction since it is the main protein that binds medicines and other physiological components. In this perspective, binary complex have been synthesized and characterized, from vanadium metal and acetylacetone(4,4,4-trifluoro-1-(2-theonyl)-1,3-butanedione). Imidazole, 2-Methyl-imidazole, and 2-Ethyl-imidazole auxiliary ligands were employed for the synthesis of ternary complexes. Additionally, UV absorption and fluorescence emission spectroscopy were used to examine the binding interactions between vanadium complexes and Bovine Serum Albumin. The outcomes of the binding studies and spectral approaches were in strong agreement with one another. These complexes upon inoculation into diabetes-induced Wistar rats stabilized their serum glucose levels within 3 days. From various studies, it was discovered that the ordering of glucose-lowering actions of these metal complexes were equivalent. The vanadium ternary metal complex derived from (4,4,4-trifluoro-1-(2-theonyl)-1,3-butanedione) and imidazole as ligands is the best among the other metal vanadium complexes.

Synergistically Enhanced Electrochemical Sensing of Food Adulterant in Milk Sample at Erbium Vanadate/Graphitic Carbon Nitride Composite.

Dimetridazole (DMZ), a nitroimidazole derivative, is a notable antibiotic that has garnered growing interest in the medical community owing to its noteworthy pharmacological and toxicological properties. Increasing interest is being directed toward developing high-performance sensors for continuous monitoring of DMZ in food samples. This research investigated an electrochemical sensor-based nano-sized ErVO4 attached to a sheet-like g-CN-coated glassy carbon electrode to determine dimetridazole (DMZ). The chemical structure and morphological characterization of synthesized ErVO4@g-CN were analyzed with XRD, FTIR, TEM, and EDS. Irregular shapes of ErVO4 nanoparticles are approximately 15 nm. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were followed to examine the electrochemical performance in pH 7 phosphate buffer solution for higher performance. This electrochemical sensor showed a low detection limit (LOD) of 1 nM over a wide linear range of 0.5 to 863.5 µM. Also, selectivity, stability, repeatability, and reproducibility studies were investigated. Furthermore, this electrochemical sensor was applied to real-time milk sample analysis for the detection of analytes.

Non-Covalent and Covalent Binding of New Mixed-Valence Cage-like Polyoxidovanadate Clusters to Lysozyme.

The high-resolution X-ray structures of the model protein lysozyme in the presence of the potential drug [VIVO(acetylacetonato)2] from crystals grown in 1.1 M NaCl, 0.1 M sodium acetate at pH 4.0 reveal the binding to the protein of different and unexpected mixed-valence cage-like polyoxidovanadates (POVs): [V15O36(OH2)]5-, which non-covalently interacts with the lysozyme surface, [V15O33(OH2)]+ and [V20O51(OH2)]n- (this latter based on an unusual {V18O43} cage) which covalently bind the protein. EPR spectroscopy confirms the partial oxidation of VIV to VV and the formation of mixed-valence species. The results indicate that the interaction with proteins can stabilize the structure of unexpected - both for dimension and architecture - POVs, not observed in aqueous solution.

Perovskite-Type Manganese Vanadate Sonosensitizers with Biodegradability for Enhanced Sonodynamic Therapy of Cancer.

Sonodynamic therapy (SDT) has attracted intensive attention, but is still hindered by low sonosensitization and non-biodegradability of the traditional sonosensitizers. Herein, perovskite-type manganese vanadate (MnVO3 ) sonosensitizers integrating high reactive oxide species (ROS) production efficiency and appropriate bio-degradability are developed for enhanced SDT. Taking advantage of the intrinsic properties of perovskites such as narrow bandgap and substantial oxygen vacancies, MnVO3 shows a facile ultrasound (US)-triggered electrons-holes separation and restrained recombination, thus enhancing the ROS quantum yield in SDT. Furthermore, MnVO3 exhibits a considerable chemodynamic therapy (CDT) effect under the acidic condition probably owing to the presence of manganese and vanadium ions. Due to the presence of high-valent vanadium, MnVO3 can also eliminate glutathione (GSH) within the tumor microenvironment, which synergistically amplifies the efficacy of SDT and CDT. Importantly, the perovskite structure bestows MnVO3 with superior biodegradability, which alleviates the long-term presence of residues in metabolic organs after therapeutic actions. Based on these characteristics, US-assisted MnVO3 achieves an excellent antitumor outcome along with low systemic toxicity. Overall, perovskite-type MnVO3 may be promising sonosensitizers for highly efficient and safe treatment of cancer. The work attempts to explore the potential utility of perovskites in the design of degradable sonosensitizers.

Shewanella metallivivens sp. nov., a deep-sea hydrothermal vent tube worm endobiont capable of dissimilatory anaerobic metalloid oxyanion reduction.

A polyphasic taxonomic study was carried out on a Gram-stain-negative and rod-shaped strain, ER-Te-42B-LightT, isolated from the tissue of a tube worm, Riftia pachyptila, collected near a deep-sea hydrothermal vent of the Juan de Fuca Ridge in the Pacific Ocean. This bacterium was capable of performing anaerobic respiration using tellurite, tellurate, selenite and orthovanadate as terminal electron acceptors. While facultatively anaerobic, it could aerobically resist tellurite, selenite and orthovanadate up to 2000, 7000 and 10000 µg ml-1, respectively, reducing each oxide to elemental forms. Nearly complete 16S rRNA gene sequence similarity related the strain to Shewanella, with 98.8 and 98.7 % similarity to Shewanella basaltis and Shewanella algicola, respectively. The dominant fatty acids were C16 : 0 and C16 : 1. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol and MK-7 was the predominant quinone. DNA G+C content was 42.5 mol%. Computation of average nucleotide identity and digital DNA-DNA hybridization values with the closest phylogenetic neighbours of ER-Te-42B-LightT revealed genetic divergence at the species level, which was further substantiated by differences in several physiological characteristics. Based on the obtained results, this bacterium was assigned to the genus Shewanella as a new species with the name Shewanella metallivivens sp. nov., type strain ER-Te-42B-LightT (=VKM B-3580T=DSM 113370T).

Topical vanadate improves tensile strength and alters collagen organisation of excisional wounds in a mouse model.

Wound dehiscence, oftentimes a result of the poor tensile strength of early healing wounds, is a significant threat to the post-operative patient, potentially causing life-threatening complications. Vanadate, a protein tyrosine phosphatase inhibitor, has been shown to alter the organisation of deposited collagen in healing wounds and significantly improve the tensile strength of incisional wounds in rats. In this study, we sought to explore the effects of locally administered vanadate on tensile strength and collagen organisation in both the early and remodelling phases of excisional wound healing in a murine model. Wild-type mice underwent stented excisional wounding on their dorsal skin and were divided equally into three treatment conditions: vanadate injection, saline injection control and an untreated control. Tensile strength testing, in vivo suction Cutometer analysis, gross wound measurements and histologic analysis were performed during healing, immediately upon wound closure, and after 4 weeks of remodelling. We found that vanadate treatment significantly increased the tensile strength of wounds and their stiffness relative to control wounds, both immediately upon healing and into the remodelling phase. Histologic analysis revealed that these biomechanical changes were likely the result of increased collagen deposition and an altered collagen organisation composed of thicker and distinctly organised collagen bundles. Given the risk that dehiscence poses to all operative patients, vanadate presents an interesting therapeutic avenue to improve the strength of post-operative wounds and unstable chronic wounds to reduce the risk of dehiscence.

Rare-earth orthovanadate nanoparticles trigger Ca2+-dependent eryptosis.

Introduction. Rare-earth orthovanadate nanoparticles (ReVO4:Eu3+, Re = Gd, Y or La) are promising agents for photodynamic therapy of cancer due to their modifiable redox properties. However, their toxicity limits their application.Objective. The aim of this research was to elucidate pro-eryptotic effects of GdVO4:Eu3+and LaVO4:Eu3+nanoparticles with identification of underlying mechanisms of eryptosis induction and to determine their pharmacological potential in eryptosis-related diseases.Methods. Blood samples (n= 9) were incubated for 24 h with 0-10-20-40-80 mg l-1GdVO4:Eu3+or LaVO4:Eu3+nanoparticles, washed and used to prepare erythrocyte suspensions to analyze the cell membrane scrambling (annexin-V-FITC staining), cell shrinkage (forward scatter signaling), reactive oxygen species (ROS) generation through 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) staining and intracellular Ca2+levels via FLUO4 AM staining by flow cytometry. Internalization of europium-enabled luminescent GdVO4:Eu3+and LaVO4:Eu3+nanoparticles was assessed by confocal laser scanning microscopy.Results.Both nanoparticles triggered eryptosis at concentrations of 80 mg l-1. ROS-mediated mechanisms were not involved in rare-earth orthovanadate nanoparticles-induced eryptosis. Elevated cytosolic Ca2+concentrations were revealed even at subtoxic concentrations of nanoparticles. LaVO4:Eu3+nanoparticles increased intracellular calcium levels in a more pronounced way compared with GdVO4:Eu3+nanoparticles. Our data disclose that the small-sized (15 nm) GdVO4:Eu3+nanoparticles were internalized after a 24 h incubation, while the large-sized (∼30 nm) LaVO4:Eu3+nanoparticles were localized preferentially around erythrocytes.Conclusions.Both internalized GdVO4:Eu3+and non-internalized LaVO4:Eu3+nanoparticles (80 mg l-1) promote eryptosis of erythrocytes after a 24 h exposurein vitrovia Ca2+signaling without involvement of oxidative stress. Eryptosis is a promising model for assessing nanotoxicity.

Vanadate Bio-Detoxification Driven by Pyrrhotite with Secondary Mineral Formation.

Vanadium(V) is a redox-sensitive heavy-metal contaminant whose environmental mobility is strongly influenced by pyrrhotite, a widely distributed iron sulfide mineral. However, relatively little is known about microbially mediated vanadate [V(V)] reduction characteristics driven by pyrrhotite and concomitant mineral dynamics in this process. This study demonstrated efficient V(V) bioreduction during 210 d of operation, with a lifespan about 10 times longer than abiotic control, especially in a stable period when the V(V) removal efficiency reached 44.1 ± 13.8%. Pyrrhotite oxidation coupled to V(V) reduction could be achieved by an enriched single autotroph (e.g., Thiobacillus and Thermomonas) independently. Autotrophs (e.g., Sulfurifustis) gained energy from pyrrhotite oxidation to synthesize organic intermediates, which were utilized by the heterotrophic V(V) reducing bacteria such as Anaerolinea, Bacillus, and Pseudomonas to sustain V(V) reduction. V(V) was reduced to insoluble tetravalent V, while pyrrhotite oxidation mainly produced Fe(III) and SO42-. Secondary minerals including mackinawite (FeS) and greigite (Fe3S4) were produced synchronously, resulting from further transformations of Fe(III) and SO42- by sulfate reducing bacteria (e.g., Desulfatiglans) and magnetotactic bacteria (e.g., Nitrospira). This study provides new insights into the biogeochemical behavior of V under pyrrhotite effects and reveals the previously overlooked mineralogical dynamics in V(V) reduction bioprocesses driven by Fe(II)-bearing minerals.

Elucidating Multiple Electron-Transfer Pathways for Metavanadate Bioreduction by Actinomycetic Streptomyces microflavus.

While microbial reduction has gained widespread recognition for efficiently remediating environments polluted by toxic metavanadate [V(V)], the pool of identified V(V)-reducing strains remains rather limited, with the vast majority belonging to bacteria and fungi. This study is among the first to confirm the V(V) reduction capability of Streptomyces microflavus, a representative member of ubiquitous actinomycetes in environment. A V(V) removal efficiency of 91.0 ± 4.35% was achieved during 12 days of operation, with a maximum specific growth rate of 0.073 d-1. V(V) was bioreduced to insoluble V(IV) precipitates. V(V) reduction took place both intracellularly and extracellularly. Electron transfer was enhanced during V(V) bioreduction with increased electron transporters. The electron-transfer pathways were revealed through transcriptomic, proteomic, and metabolomic analyses. Electrons might flow either through the respiratory chain to reduce intracellular V(V) or to cytochrome c on the outer membrane for extracellular V(V) reduction. Soluble riboflavin and quinone also possibly mediated extracellular V(V) reduction. Glutathione might deliver electrons for intracellular V(V) reduction. Bioaugmentation of the aquifer sediment with S. microflavus accelerated V(V) reduction. The strain could successfully colonize the sediment and foster positive correlations with indigenous microorganisms. This study offers new microbial resources for V(V) bioremediation and improve the understanding of the involved molecular mechanisms.

Polymerization State of Vanadyl Species Affects the Catalytic Activity and Arsenic Resistance of the V2O5-WO3/TiO2 Catalyst in Multipollutant Control of NOx and Chlorinated Aromatics.

The conventional V2O5-WO3/TiO2 catalyst suffers severely from arsenic poisoning, leading to a significant loss of catalytic activity. The doping of Al or Mo plays an important role in promoting the arsenic resistance on NH3 selective catalytic reduction (NH3-SCR), but their promotion mechanism remains in debate and has yet to be explored in multipollutant control (MPC) of NOx and chlorinated organics. Herein, our experimental characterizations and density functional theory (DFT) calculations confirmed that arsenic species preferentially adsorb on both Al and Mo to form arsenate, thereby avoiding bonding to the catalytically active V sites. More importantly, Al doping partially converted the polymeric vanadyl species into monomeric ones, thereby inhibiting the near-surface and bulk lattice oxygen mobility of the V2O5-WO3/TiO2 catalyst, while Mo doping resulted in vanadyl polymerization with an enriched V5+ chemical state and exhibited superior MPC activity and COx selectivity. Our work shows that antipoisoning catalysts can be designed with the combination of site protection and occurrence state modification of the active species.

Uncovering the Dinuclear Mechanism of NO2-Involved NH3-SCR over Supported V2O5/TiO2 Catalysts.

Commercial vanadium oxide catalysts exhibit high efficiency for the selective catalytic reduction (SCR) of NO with NH3, especially in the presence of NO2 (i.e., occurrence of fast NH3-SCR). The high-activity sites and their working principle for the fast NH3-SCR reaction, however, remain elusive. Here, by combining in situ spectroscopy, isotopic labeling experiments, and density functional theory (DFT) calculations, we demonstrate that polymeric vanadyl species act as the main active sites in the fast SCR reaction because the coupling effect of the polymeric structure alters the elementary reaction step and effectively avoids the high energy barrier of the rate-determining step over monomeric vanadyl species. This study unveils the high-activity dinuclear mechanism of the NO2-involved SCR reaction over vanadia-based catalysts and provides a fundamental basis for developing high-efficiency and low V2O5-loading SCR catalysts.

Combustion Synthesis and Study of Double Charge Transfer in Highly Efficient Cool White-emitting Dy3+ Activated Vanadate-based Nanophosphor for Advanced Solid-state Lighting.

A series of Ca9Gd(VO4)7: Dy3+ (x = 0.01-0.20) nanophosphor crystals emitting a cool white light were synthesized by solution combustion methodology. The X-ray diffraction patterns were analyzed and processed using Rietveld refinement. The fabricated nanophosphor was found to crystallize in a trigonal crystal lattice with space group R3c(161). The morphological behavior of the prepared nanophosphor was investigated using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The photoluminescence properties of the nanophosphor correspond to cool white emission upon near-ultraviolet (NUV) excitation at 327 nm due to 4F9/2 → 6H15/2 (bluish) and 4F9/2 → 6H13/2 (yellowish) radiative relaxations at 487 nm and 576 nm respectively. Also, there is a strong occurrence of double charge transfer from O2- ions to Dy3+ and V5+ ions with the latter being stronger due to the high positive charge of V5+ ions. Color coordinates (x = 0.2878, y = 0.3259) are consistent with white emission. Auzel's model was implemented to examine the non-radiative relaxation (113.5 ms-1), radiative lifetime (1.4856 ms), and quantum efficiency (83.13%) values. The crystalline and optical behavior of the synthesized cool white emitting nanophosphor facilitates its use in near-UV-based WLEDs and other advanced solid-state lighting.