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[Display omitted] • Cu 1.94 S-ZnS-CdS ternary heteronanoplates with a continuous sublattice structure. • Efficient carrier transfer enhances carrier separation process. • Photocatalytic hydrogen evolution efficiency and stability. • Photocatalysts with precisely defined materials and interfaces. Incorporating precise morphology control and efficient carrier separation into single-nanoparticle heterojunctions to achieve high photocatalytic efficiency remains a significant challenge. Here, we synthesized Cu 1.94 S-ZnS-CdS ternary heteronanoplates (HNPs) with a continuous sublattice structure using cation exchange reactions. Femtosecond transient absorption spectroscopy (TAS) confirms that ternary heterojunction enhances carrier separation efficiency, demonstrating both rapid separation (∼0.2 ps) and an extended lifetime (∼1512 ps). The synergistic combination results in a significantly enhanced hydrogen evolution rate of 2.012 mmol·g−1·h−1, which is 17 times and 183 times higher than that achieved by pure CdS and ZnS, respectively. Furthermore, there is no significant decrease in the activity of Cu 1.94 S-ZnS-CdS in photocatalytic hydrogen evolution after 288 days of placement. Our work offers an alternative approach for designing noble-metal-free photocatalysts with precisely defined materials and interfaces, aiming to enhance both photocatalytic hydrogen evolution efficiency and stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 3 O 4 /RuO 2 heterojunction interface is construct through an ion exchange reaction and pyrolysis. • The optimal Co 3 O 4 /RuO 2 -4 electrocatalyst exhibits outstanding oxygen evolution reaction activity and remarkable stability at large current density. • The electronic structures of Co 3 O 4 /RuO 2 are modulated at the heterointerface which regulating electron redistribution. Exploring effective strategies for developing new high-efficiency catalysts for water splitting is essential for advancing hydrogen energy technology. Herein, Co 3 O 4 /RuO 2 heterojunction interface is construct through ion exchange reaction and pyrolysis. The as-synthesized Co 3 O 4 /RuO 2 -4 exhibits outstanding oxygen evolution reaction (OER) activity at the current density of 100 mA cm−2 with a low overpotential of 276 mV, and remarkable stability (maintaining activity for 60 h at 100 mA cm−2). Experimental results and theoretical calculations reveal that the electrons around the heterogeneous interface transferred from RuO 2 to Co 3 O 4 , resulting in electron redistribution and optimization of energy barriers for OER intermediates. This unique composite catalyst structure offers a new potential for designing efficient oxygen electrocatalysts at large current density. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heterogeneous Ni–Co phosphide/phosphate with a specific hollow sea-urchin-like structure has been constructed. • The heterogeneous sample exhibits improved electrolyte interfacial property from the specific hollow sea-urchin-like structure. • The heterogeneous sample combines the merits from bimetal phosphide and phosphate. • The heterogeneous sample exhibits promising potential for both HSC and AZB applications. Constructing well-defined nanostructures consisting of the multiple components with distinctive features are a promising but challenging strategy to develop advanced electroactive materials for energy storage applications. Herein, heterogeneous Ni–Co phosphide/phosphate with a specific hollow sea-urchin-like structure has been synthesized as advanced electroactive materials for both hybrid supercapacitor (HSC) and alkaline zinc-metal battery (AZB) applications. The heterogeneous Ni–Co phosphide/phosphate combines the merits of improved electrolyte interfacial property from the specific hollow sea-urchin-like structure, high electron-conductivity of phosphide, and better ion adsorption and solid diffusion property of phosphate. As a result, the Ni–Co phosphide/phosphate achieves a high capacity to 180.7 mA h g−1 at 1 A g−1, excellent rate capability of 51% capacity retention when the specific current increases by 50 times, and stable cycling stability of 85% capacity retention when cycled for 1000 cycles. Ex situ test was conducted to investigate the formation mechanism for the hollow and sea-urchin-like structure, which can be ascribed to the anion exchange reaction between pre-formed hydroxide and CO 3 2– ions. When used to assemble HSCs with reduced graphene oxide (RGO), the HSCs exhibit a high specific energy of 49.4 W h kg−1, an ultrahigh specific power to 11.7 kW kg−1, and an eminent cycling stability over 10,000 cycles. Meanwhile, Ni 2 Co–P/PO x -based AZB also achieves both high-energy and high-power performance with the specific energy of 308.0 W h kg−1 at 828.4 W kg−1 and 117.4 W h kg−1 at 30.8 kW kg−1. These results above suggest that heterogeneous Ni–Co phosphide/phosphate has great potential to be used as a candidate for both HSC and AZB applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Seven CuI hybrid micron phosphors with the emission from blue 450 nm to red 636 nm were sustainably synthesized via the aqueous PVP micelle-assisted assembly route. • The micron phosphors present excellent stability in water and can be dispersed in the aqueous solution of PVP or PVA to form homogenous luminescent inks. • The applications including anticounterfeiting, free-standing monochromatic and multichromatic emitting films and phosphors for LEDs were demonstrated. Low-cost and eco-friendly CuI hybrid compounds with various structures have recently attracted increasing attention due to their excellent optical properties and promising phosphor applications. However, the poor solubility and solution processability of bulk powders with agglomerated particle limited their practical applications greatly. In this work, we reported the self-assembly formation of CuI hybrid micron phosphors via the aqueous PVP micelle-assisted assembly route. Seven CuI hybrid micron phosphors with the emission from blue 450 nm to red 636 nm have been successfully synthesized. Among them, CuI-pyridine hybrid micron phosphors can be obtained via the reaction of CuI with various pyridines. PVP limits the size growth of the phosphors efficiently and it also plays an important role in controlling the distinct crystal phase formation. Whereas, micron phosphors based on bidentate ligands including 2-propylpyrazine, 5-bromopyrimidine or 4,4′-bipyridine need to be prepared via ligand exchange reaction. The micron phosphors present excellent stability in water and can be dispersed in the aqueous solution of PVP or PVA to form homogenous luminescent composites. The luminescent composites based on PVP are easy to use for fabricating anti-counterfeiting patterns via brush-painting or screen-printing. On the other hand, PVA composites can be applied for preparing free standing monochromatic or multichromatic emitting films as color convertor for display backlight. The PVA composites also exhibit the promising phosphor application for light-emitting diode (LED). Especially, the white LED can be directly realized via optimizing the mixing ratio of blue and orange phosphors. [ABSTRACT FROM AUTHOR]

Ru@Fe-Ni(OH) 2 /NF catalyst fabricated through Fe-doped and interfacial Ru nanoclusters co-engineering of Ni(OH) 2 nanosheets directly grafted on Ni foam exhibits excellent activity towards oxygen evolution reaction (OER) in alkaline media with an overpotential of 266.4 mV to achieving a current density of 50 mA cm−2 in 1 M KOH. Our results show that we have successfully developed an efficient OER catalyst for green and efficient electrocatalytic hydrolysis to produce H 2 and O 2 , providing a promising method for clean H 2 production. [Display omitted] The creation of inexpensive, high-performance catalysts to reduce the overpotential of the oxygen evolution reaction (OER) process is critical for the electrolysis of water for hydrogen production. Therefore, we applied a one-step hydrothermal method using cation exchange reaction (CER) to prepare Fe-doped and interfacial Ru nanoclusters co-engineered Ni(OH) 2 nanosheets directly grafted on Ni foam (Ru@Fe-Ni(OH) 2 /NF) for OER process. Results of electrochemical tests reveal that Ru@Fe-Ni(OH) 2 /NF has excellent OER activity, and its overpotential (η) is only 266.4 mV when the current density is 50 mA cm−2 in 1 M KOH solution, even lower than that of commercial OER catalyst RuO 2 (355 mV). The Tafel slope also decreases from 133.8 mV dec−1 for pristine Ni(OH) 2 /NF material to 24.1 mV dec−1 for Ru@Fe-Ni(OH) 2 /NF, indicating the higher charge transfer rates and fastest kinetics for water oxidation. At an overpotential of 300 mV the optimal turnover frequency (TOF) of 0.062 s−1 for Ru@Fe-Ni(OH) 2 /NF is achieved compared to that of Ni(OH) 2 /NF (0.014 s−1, NN), demonstrating the fast reaction kinetics of the as-prepared electrocatcalyst. After 24 h stability test, the catalytic activity of Ru@Fe-Ni(OH) 2 /NF was only attenuated by 2 %, showing excellent OER stability and durability. Our results show that we have successfully developed an efficient OER catalyst for green and efficient electrocatalytic hydrolysis to produce H 2 and O 2 , providing a promising method for clean H 2 production. [ABSTRACT FROM AUTHOR]

[Display omitted] Regulating electronic structure and enriching active sites of photocatalysts are effective strategies to promote hydrogen evolution. Herein, a unique Ni x Cd 1-x S-Ni0 photocatalyst, including the surface nickel (Ni) doping and atomic Ni0 anchoring sites, is successfully prepared by Ni2+ ions exchange reaction (Ni 2+ + CdS → Ni x Cd 1- x S) and in-situ photo-induction of Ni0 (N i 2 + + N i x C d 1 - x S → h ν N i x C d 1 - x S - N i 0) , respectively. As to Ni doping, the Ni replaced cadmium (Cd) atoms introduce hybridized states around the Fermi level, modulating the electronic structure of adjacent S atoms and optimizing the photocatalytic activity of sulfur (S) atoms. Besides, photogenerated Ni0 atoms, anchored on unsaturated S atoms, act as charge transfer bridges to reduce Ni2+ ions in the solution to Ni clusters (N i x C d 1 - x S - N i 0 → n e - N i x C d 1 - x S - N i). Subsequently, the displacement reaction of Ni clusters with protons (H+) spontaneously proceeds to produce hydrogen (H 2) in an acidic solution (N i x C d 1 - x S - N i → 2 H + H 2 ↑ + N i 2 + + N i x C d 1 - x S - N i 0). The equilibrium of photo-deposition/dissolution of Ni clusters realizes the construction of dynamic active sites, providing sustainable reaction centers and enhancing surface redox kinetics. The Ni x Cd 1-x S-Ni0 exhibits a high hydrogen evolution rate of 428 mmol·h−1·g−1 with a quantum efficiency of 75.6 % at 420 nm. This work provides the optimal S electronic structure for photocatalytic H 2 evolution and constructs dynamic Ni clusters for chemical replacement reaction. This work provides the optimal S electronic structure for photocatalytic H 2 evolution and constructs dynamic Ni clusters for displacement reaction, opening a dual pathway for efficient water reduction. [ABSTRACT FROM AUTHOR]

Flavin disulfide reductases (FDRs) are FAD-dependent enzymes that transmit electrons from NAD(P)H to reduce specific oxidant substrate disulfides. These enzymes have been studied extensively, most particularly the paradigm examples: glutathione reductase and thioredoxin reductase. The common, though not universal, traits of the family include a tyrosine- or phenylalanine-gated binding pocket for NAD(P) nicotinamides adjacent to the FAD isoalloxazine re-face, and a disulfide stacked against the si-face of the isoalloxazine whose dithiol form is activated for subsequent exchange reactions by a nearby histidine acting as a base. This arrangement promotes transduction of the reducing equivalents for disulfide exchange relay reactions. From an observational standpoint the proximal parallel stacking of three redox moieties induces up to three opportunities for unique charge transfer interactions (NAD(P)H FAD, NAD(P)+•FADH 2 , and FAD•thiolate). In transient state, the charge transfer transitions provide discrete signals to assign reaction sequences. This review summarizes the lineage of observations for the FDR enzymes that have been extensively studied. Where applicable and in order to chart a consistent interpretation of the record, only data derived from studies that used anaerobic methods are cited. These data reveal a recurring theme for catalysis that is elaborated with specific additional functionalities for each oxidant substrate. [Display omitted] • Review of the NAD(P)H-dependent flavoprotein disulfide reductases. • First review of its type to include only anaerobic kinetic or equilibrium observations. • Hierarchy for enzymes described based on number of disulfide/dithiol exchange reactions in catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] Surface modification of ligand protected nanoparticles (NPs) can be driven by ligand exchange reactions (LER). Little is known about the mechanism of this reaction, especially when the particles are not spherical. Here, we use the intrinsic hot spots generated on the corners/edges of 40 nm silver nanocubes (AgNCs) and the extrinsic hot spots generated by the aggregation of AgNCs to obtain strong enhancements in surface enhanced Raman scattering (SERS) to monitor the displacement of poly(vinylpyrrolidone) with either a hydrophilic (sodium 11-mercapto-1-undecanesulfonate, MUS) or a hydrophobic ligand (1-octanethiol, OT). By focusing on the ratio (R) between the trans and gauche bands of the alkyl backbones of the ligands as an indicator of local order, we find that the LER proceeds in two different ways, particularly regarding the arrangement of the incoming ligands. In the case of OT, R becomes large almost immediately and stays high throughout the reaction, while in the case of MUS, R starts low and increases only towards the end of the reaction. We interpret the first behaviour as a LER that proceeds via the formation of densely packed and ordered OT islands, practically from the beginning of the reaction, that gradually grow over time. In the case of MUS, our interpretation is that molecules randomly deposit on the surface and form denser monolayer regions as the LER proceeds. Both monolayers evolved towards a homogeneous topography that corresponds to an ordered state (near all- trans) in the later stages (R≫1). Such mechanisms may be extended to the cube faces (as planar scaffolds) since clear differences in the topographic profile were found by Atomic Force Microscopy (AFM). [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, Cu 2 S as the outer shell is grown on CdS nanorods (NRs) to construct rod-shell nanostructures (CdS/Cu 2 S) by a rapid, scalable and facile cation exchange reaction. The CdS NRs are firstly synthesized by a hydrothermal route, in which thiourea as the precursor of sulfur and ethylenediamine (EDA) as the solvent. And then, the outer shells of CdS NRs are successfully exchanged by Cu 2 S via a cation exchange reaction. The obtained CdS/Cu 2 S rod-shell NRs exhibit much enhanced activity of hydrogen production (640.95 μmol h−1 g−1) in comparison with pure CdS NRs (74.1 μmol h−1 g−1) and pure Cu 2 S NRs (0 μmol h−1 g−1). The enhanced photocatalytic activity of CdS/Cu 2 S rod-shell NRs owns to the following points: i) the photogenerated electrons generated by CdS quickly migrate to Cu 2 S without any barrier due to rod-shell structure by the in-situ cation exchange reaction, a decreased carrier recombination is achieved; ii) Cu 2 S as outer shells broaden the light absorption range of CdS/Cu 2 S rod-shell NRs into visible or even NIR light, which can produce more electrons and holes. This work inspires people to further study the rod-shell structured photocatalyst through the cation exchange strategy to further solar energy conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] Crystalline hydrates of swelling clay minerals (smectites) exhibit a strong coupling between their ion exchange and hydration/dehydration reactions. The uptake or removal of water from smectite interlayers as a result of a change in the environmental conditions also leads to the partitioning of cations. Three factors, the solid ion composition, the solid basal spacing/water content, and the aqueous solution composition, are all implicated in controlling the thermodynamics of ion exchange. However, conventional approaches to measuring the exchange free energy cannot separate the influence of each of these individual factors. Here, we explore the energetics of the swelling and ion exchange reactions in montmorillonite using a potential of mean force approach and the thermodynamic integration method within molecular simulations. We investigate the influence of solution and clay composition on the spontaneity of the reactions, focusing on the 2 water-layer hydration state. The swelling simulations provide the equilibrium water content, interlayer water structure, and basal spacings, while thermodynamic integration of sodium–potassium exchange in the aqueous solution and solid phase are combined to calculate ion exchange free energies as a function of solution composition. Results confirm the tendency of the clay to collapse to lower hydration states as the concentration of the solution increases. Changes to the equilibrium water content, even at fixed hydration states, and the composition of the mixed electrolyte solution play a critical role in driving ion exchange and the selectivities of the clay to the exchanged cation, while the composition of the solid phase is shown to be insignificant. These findings underscore the extreme sensitivity of clay swelling and ion exchange thermodynamics to small (tenths of an Angstrom) deviations in layer spacing. [ABSTRACT FROM AUTHOR]

[Display omitted] We propose a general, versatile and broad in scope two-steps approach for the elaboration of cross-linked polymer microparticles (µPs) with tunable functionalities and surface properties. Surface-functionalized cross-linked polymer µPs with diameter in the 80 μm range are prepared by the combination of: 1) suspension free radical copolymerization of styrene, propargyl methacrylate and 1,6-hexanediol dimethacrylate, 2) subsequent covalent tethering of a variety of azide-functionalized moieties (i.e. rhodamine B fluorescent dye or poly(ethylene glycol) (PEG) brush precursor) by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and, 3) optional N -alkylation of the 1,2,3-triazole groups followed by anion exchange reaction to afford covalently-tethered 1,2,3-triazolium ionic liquids with iodide or cresol red counter-anions. The resulting µPs are characterized by laser diffraction, differential scanning calorimetry, as well as by optical, confocal fluorescence, scanning electron and atomic force microscopies. Finally, the rheological properties of concentrated suspensions (volume fractions of 0.40 and 0.44) of the different synthesized µPs dispersed in a 1:1 (vol/vol) mixture of polyalkylene glycol and water are studied. The modification of µPs surface properties contributes not only to change the stability of the suspensions against flocculation, but also to significantly modify their rheological behavior at high shear stresses. This represents a clear experimental evidence of the importance of non-hydrodynamic contact forces in the rheology of non-Brownian suspensions (NBSs). [ABSTRACT FROM AUTHOR]

[Display omitted] • The catalytic efficiency upon Pt/ZSM-5 is 830 times higher that of commercial Pt-C at the optimum condition. • Water cluster creates an effective route to deliver proton to the reactive site. • The hydrogen transfer between Pt and Brønsted acid involves the spillover and reverse spillover. Liquid-phase hydrogen isotopes exchange between hydrogen and water is a promising route for the hydrogen isotopes separation from water, catalyzed by the metal Pt with hydrophobic coating to surmount the flooding of reactive sites. However, poor water activation ability on Pt has limited the catalytic efficiency of Pt-based catalysts and hindered their application. Herein, we report a bifunctional Pt/ZSM-5 catalyst with hydrophobic modification by surface silylation for H 2 -HDO isotope catalytic exchange. The integration of metallic Pt and Brønsted acid (BA) sites in the microporous ZSM-5 boosts the catalytic efficiency of deuterium extraction by two orders of magnitude compared to commercial Pt-C at the optimum condition. In-situ spectroscopic and theoretical studies demonstrated that HDO-H 2 O preferentially adsorbs on BA sites (-Si-OH-Al) to form protonated water clusters stabilized by hydrogen-bonded network or to undergo the proton exchange to leave deuterium on zeolite framework as a new acidic site ([AlO 4 D]). Under the attractive interaction, the dissociated hydrogen on Pt clusters releases partial electrons to form positively-charged hydrogen, which further transfers to the [AlO 4 D] sites or protonated water clusters by interfacial spillover to produce the overcharging intermediates. These intermediates cleave their O-D bonds to form positively charged D, which ultimately spills back to Pt cluster and combines with the remaining electron to desorb in the form of HD. The synergistic effect between Pt and BA sites creates a new pathway of hydrogen transfer, which enables the more efficient hydrogen-water isotope exchange on the bifunctional Pt/ZSM-5 catalyst. [ABSTRACT FROM AUTHOR]

In this study, lanthanum carbonate (LC) was selected as a capping agent to examine its effectiveness in immobilizing sediment internal phosphorus (P), arsenic (As) and tungsten (W). With a 180-day incubation experiment, it was determined that LC capping efficiently reduced the concentrations of soluble reactive P (SRP), soluble As and soluble W in pore water, with the highest reduction rate of 83.39%, 56.21% and 68.52%, respectively. The primary mechanisms involved in the adsorption of P, As and W by LC were precipitation reactions and ligand exchange. Additionally, P, As and W were immobilized by LC capping through the transformation of fractions from mobile and less stable forms to more stable forms. Furthermore, LC capping led to an increase in the Eh value, which promoted the oxidation of soluble Fe (Ⅱ) and soluble Mn. The significantly positive correlation and synchronized variations observed between SRP, soluble As, soluble W, and soluble Fe (II) indicated that the effects of LC on Fe redox played a crucial role in immobilizing sediment internal P, As and W. However, the oxidation of Mn, promoted by LC, played a more significant role in immobilizing sediment internal As than P and W. These effects resulted in LC capping achieving the highest reduction of SRP, soluble As and soluble W flux at 145.22, 22.19, and 0.58 μg m−2d−1. It is of note that LC capping did not lead to an elevated release hazard of Co, Ni, Cu, and Pb, barring Cd. Besides, LC capping did not modify the entire microbial communities in the sediment, but altered the proportional representation of specific microorganisms. Generally, LC has potential as a capping agent capable of simultaneously immobilizing sediment internal P, As and W. [Display omitted] • LC capping can simultaneously adsorbed SRP, soluble As and soluble W. • LC capping promoted the conversion of P, As and W fractions from mobile to stable. • LC capping increased the Eh values. • LC-affected Fe/Mn redox plays a key role in immobilizing sediment P, As and W. • LC capping did not result in an increased release risk of Co, Ni, Cu and Pb. [ABSTRACT FROM AUTHOR]

[Display omitted] Photocatalytic hydrogen evolution is one of the most promising approaches for efficient solar energy conversion. The light-harvesting ability and interfacial structure of heterostructured catalysts regulate the processes of photon injection and transfer, which further determines their photocatalytic performances. Here, we report a Janus Cu 1.94 S-ZnS nano-heterostructured photocatalyst synthesized using a facile stoichiometrically limited cation exchange reaction. Djurleite Cu 1.94 S and wurtzite ZnS share the anion skeleton, and the lattice mismatch between immiscible domains is ∼1.7%. Attributing to the high-quality interfacial structure, Janus Cu 1.94 S-ZnS nanoheterostructures (NHs) show an enhanced photocatalytic hydrogen evolution rate of up to 0.918 mmol h−1 g−1 under full-spectrum irradiation, which is ∼38-fold and 17-fold more than those of sole Cu 1.94 S and ZnS nanocrystals (NCs), respectively. The results indicate that cation exchange reaction is an efficient approach to construct well-ordered interfaces in hybrid photocatalysts, and it also demonstrates that reducing lattice mismatch and interfacial defects in hybrid photocatalysts is essential for enhancing their solar energy conversion performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Fabricating a high-performance adsorbent as a desirable candidate for removing Pb2+ from aqueous water remains a challenge. Aramid nanofibers (ANFs) are promising building blocks that have realized multifunctional applications due to their intrinsic mechanical and chemical stability. Herein, an in situ loading strategy for preparing nanofiber composite aerogel was proposed by assembling ANFs into a 3D aerogel and applying it as host media for the in situ polymerization of pyrrole followed by facile redox reaction between the polypyrrole (PPy) and MnO 4 –1 to load manganese dioxide (MnO 2). The idea was to fully exploit the structural advantages of ultra-low bulk density, large specific surface area, and high porosity of ANFs, and the possible chemical adsorption characteristics of MnO 2 on the basis of ion exchange reaction. The adsorption capacity of 3D ANF/MnO 2 composite aerogel was as large as 554.36 mg/g for Pb2+. The adsorption mechanism based on an exchange reaction between Pb2+ and protons on the surface of MnO 2 was also investigated. The desorption results showed that the adsorption performance could remain up to 90% after five times of usage. In conclusion, this research provides promising insights into the preparation of high-performance lead adsorbent for water treatment. [ABSTRACT FROM AUTHOR]

• Bi 2 S 3 -BiOBr nanosheets were synthesized on TiO 2 NTA/Ti mesh. • The Bi 2 S 3 -BiOBr/TiO 2 NTAs showed the attractive hydrogen generation activity. • The active species and photocatalytic mechanism were studied. Novel energy material is the investigation focus to overcome the environment pollution and resource shortage crisis. TiO 2 nanotube arrays (TiO 2 NTA) could be used for pollutant decomposition, photoelectric conversion and H 2 , CH 4 generation. BiOBr nanosheets were fabricated on TiO 2 NTA by a solvothermal deposition method, and then transformed into Bi 2 S 3 nanosheets after the ion exchange reaction. The results revealed that the ion concentration significantly influenced the morphology, microstructure, optical harvesting and photoelectrochemical capacity of Bi 2 S 3 -BiOBr/TiO 2 NTA. The samples also exhibited high photocatalytic activity for the removal of dyes and Cr(VI), and the excellent photocurrent and photovoltage were obtained under visible light irradiation. The photocatalytic water splitting for hydrogen generation was carried out, and the photocatalytic hydrogen production rate achieved 17.26 μmol·cm−2·h−1. The photocatalyst showed the remarkable stability, and the photocatalytic ability still maintained high level after several repeated photocatalytic cycles. The photocatalytic data indicated that the Bi 2 S 3 -BiOBr/TiO 2 NTA photocatalyst provided a perfect strategy for the sensitizer deposition on TiO 2 NTA and novel approach for the photocatalytic performance improvement. [ABSTRACT FROM AUTHOR]

• Pd NPs deposited on rGO layer-coated Au nanorod catalysts were synthesized. • The rGO contributes to the control of Pd NP sizes in the catalyst synthesis. • H 2 O 2 production from H 2 and O 2 is highly promoted under visible light irradiation. • SPR of Au nanorod accelerated H 2 activation, and thus enhanced H 2 O 2 production. A promotional effect of surface plasmon resonance (SPR) on direct hydrogen peroxide (H 2 O 2) formation from H 2 and O 2 over a structure-controlled Pd-Au catalytic system is reported herein. Pd NPs supported on reduced graphene oxide (rGO) layer-coated Au nanorod (NR) nanocomposite catalysts were synthesized, and the structure was confirmed by multiple characterization techniques. H 2 O 2 production is highly enhanced under visible light irradiation in the direct H 2 O 2 formation from H 2 and O 2. The H 2 O 2 decomposition test and the H 2 -D 2 exchange reaction reveal that the SPR of Au NRs facilitates H 2 activation on the Pd NP surface, leading to efficient H 2 O 2 production. Furthermore, the rGO layer not only functions as an electron mediator in the catalytic reaction, but also contributes to the control of Pd NP sizes in the catalyst synthesis. [ABSTRACT FROM AUTHOR]

DNA molecules that contain single Holliday junctions have served as model substrates to investigate the pathway in which homologous recombination intermediates are processed. However, the preparation of DNA containing Holliday junctions in high yield remains a challenge. In this work, we used a nicking endonuclease to generate gapped DNA, from which α-structured DNA or figure-8 DNA were created via RecA-mediated reactions. The resulting DNA molecules were found to serve as good substrates for Holliday junction resolvases. The simplified method negates the requirement for radioactive labelling of DNA, making the generation of Holliday junction DNA more accessible to non-experts. [Display omitted] • Gapped DNA was generated by nicking plasmid DNA and displacing resulting oligonucleotides. • DNA molecules formed in four-strand exchange reactions were cleaved by T7 endonuclease I and RuvC. • The method produced abundant plasmid-sized DNA containing Holliday junctions, negating the need for radiolabelling. [ABSTRACT FROM AUTHOR]

Oxygen isotope compositions of chondrules reflect the environment of chondrule formation and its spatial and temporal variations. Here, we present a theoretical model of oxygen isotope exchange reaction between molten silicate spherules and ambient water vapor with finite relative velocity. We found a new phenomenon, that is, mass-dependent fractionation caused by isotope exchange with ambient vapor moving with nonzero relative velocity. We also discussed the plausible condition for chondrule formation from the point of view of oxygen isotope compositions. Our findings indicate that the relative velocity between chondrules and ambient vapor would be lower than several 100 m s − 1 when chondrules crystallized. • We present a theoretical model of isotope exchange reaction between melt and vapor. • Our model is applicable whether the melt–vapor relative velocity is zero or not. • We found mass-dependent fractionation caused by oxygen isotope exchange. • The relative velocity must be below several 100 m/s when chondrules crystallized. [ABSTRACT FROM AUTHOR]

• Two routes to prepare Ta-Ir/SiO 2 catalysts via surface organometallic chemistry. • In-depth structural characterization of Ta, Ta-Ir and Ta-Ir 2 surface sites. • Improved catalytic performances in H/D isotope exchange and propane metathesis. A stepwise surface organometallic chemistry (SOMC) methodology consisting in using a silica-supported tantalum species, [(≡SiO)Ta(CH t Bu)(CH 2 t Bu) 2 ], as a reactive center to coordinate an iridium site, was developed to construct tantalum/iridium heterobimetallic edifices. The resulting material, MAT-2 , exhibits enhanced catalytic performances - both in H/D isotopic exchange and alkane metathesis reactions - in comparison to MAT-1 , which was prepared from the direct grafting on silica of a well-defined heterobimetallic Ta/Ir complex. We projected that the difference in catalytic activity was due to the presence of distinct active sites and we used a combination of advanced spectroscopic methods (IR, solid-state NMR and XAS spectroscopies) as well as modeling (computational studies and molecular models) to identify the structure of these surface species. These investigations point towards the presence of three types of active sites at the surface of MAT-2 : the heterobimetallic surface species, [≡SiOTa(CH 2 t Bu) 2 {IrH 2 (Cp*)}] 2-s , which is also found in MAT-1 , as well as an unanticipated heterotrimetallic species, [≡SiOTa(CH 2 t Bu) 2 {IrH 2 (Cp*)}], 3-s along with some unreacted monometallic Ta sites [(≡SiO)Ta(CH t Bu)(CH 2 t Bu) 2 ], 1-s. The well-defined trimetallic surface species 3-s was independently prepared and characterized to support this hypothesis. This study highlights the importance of the synthetic methodology used for the preparation of heterobimetallic species through SOMC, and the difficulty to obtain true single-sites surface species. [ABSTRACT FROM AUTHOR]

One of the great ambitions of structural biology is to describe structure-function relationships quantitatively. Statistical thermodynamics is a powerful, general tool for computing the behavior of biological macromolecules at equilibrium because it establishes a direct link between structure and function. Complex behavior emerges as equilibria of multiple reactions are coupled. Analytical treatment of linked equilibria scales poorly with increasing numbers of reactions and states as the algebraic constructs rapidly become unwieldy. We therefore developed a generalizable, but straightforward computational method to handle arbitrarily complex systems. To demonstrate this approach, we collected a multidimensional fluorescence landscape of an engineered fluorescent glucose biosensor and showed that its features could be modeled with ten intricately linked ligand-binding and conformational exchange reactions. This protein represents a minimalist model of sufficient complexity to encompass fundamental biomolecular structure-function relationships: two-state and multistate conformational ensembles, conformational hierarchies, osmolytes, coupling between different binding sites and coupling between ligand binding and conformational change. The successful fit of this complex, multifaceted system demonstrates generality of the method. Image 1 • Glucose biosensor fluorescence reports simultaneously on multiple reaction states. • The fluorescence landscape encompasses the major structure-function relationships. • This protein is a minimalist model for testing statistical thermodynamics methods. • Nested equilibrated states tree (NEST) is a generalizable numerical statistical thermodynamics method. • NEST addresses complex linkage relationships in biological macromolecules. [ABSTRACT FROM AUTHOR]

Surface modification of natural clay minerals with reagents containing metal chelating groups has great environmental value. The functionalization by adsorption or grafting guarantees a durable immobilization of the reactive organic groups, preventing their leaching when they are used in liquid media. The aim of this research was the designed mercapto functionalization of swelling brittle micas, Na-M n , thorough both chemical and physical mechanisms. Na-M n were functionalized with 2-mercaptoethylammonium (MEA), 2,3-dimercapto-1-propanol (BAL) and (3-mercaptopropyl)trimethoxysilane (MPTMS). The thiol concentration on swelling brittle micas is higher than the observed value for others adsorbents. The cation exchange reaction with MEA and one-step grafting with MPTMS in acid medium are the most efficient mercapto functionalization mechanism. [ABSTRACT FROM AUTHOR]

• Surface dynamics over V 2 O 5 /TiO 2 under SCR-relevant conditions was investigated. • Reversible transformation between Brønsted/Lewis sites occurred during redox cycle. • Equilibrium of two sites was determined by redox environment and produced water. • Effects of acid sites redistribution on transient reaction were discussed. The mechanisms of the selective catalytic reduction of NO with NH 3 are under debate, especially in terms of the participation of Brønsted and Lewis acid sites on V 2 O 5 /TiO 2 catalyst. Our results elucidated the dynamic nature of transformation between Brønsted and Lewis sites on V 2 O 5 /TiO 2 occurring in SCR-relevant conditions through a series of operando DRIFTS experiments. The reversible change between the two acid sites occurred not only by hydration in the presence of water but also by changing the redox state of the catalyst. We proposed that under reducing conditions, the reduced vanadium sites coordinated with ammonia to serve as additional Lewis acid sites; as a result, the reducing environment enriched the surface with Lewis sites, while the oxidizing environment gave the catalyst surface more Brønsted sites. This in turn suggested that the equilibria between the two acid sites, that is, the B/L ratio, differ depending on the reactants contained in the reaction gas. In a simulated transient SCR reaction, the instantaneous change of the gaseous environment resulted in the redistribution of ammonia on both acid sites, which occurred much more quickly than the reaction with NO. Such observations emphasize the importance of clarifying a NH 3 -equilibrated surface under reaction conditions when measuring rates of ammonia consumption. [ABSTRACT FROM AUTHOR]

• Application of B(C 6 F 5) 3 as catalyst of many chemical reactions is rapidly growing. • Chemical stability of B(C 6 F 5) 3 in the presence of silanes was evaluated. • Kinetics of reactions of B(C 6 F 5) 3 with silyl and germyl hydrides were determined. • The exchange of C 6 F 5 group with hydrogen at the boron center was observed. • The studied reactions strongly reduce catalytic efficiency of B(C 6 F 5) 3. Tris(pentafluorophenyl)borane catalyzed Si-H bond activation opens the door to numerous transition-metal-free reduction processes and is widely used in organic and polymer chemistry. However, chemical stability of B(C 6 F 5) 3 in the presence of silyl hydrides is limited, which can strongly affect its catalytic activity. Transformations of B(C 6 F 5) 3 in the presence of phenyldimethylsilane, triethylsilane and triethylgermane were studied by 19F NMR and UV spectroscopy, GC/MS and quantum-mechanical calculations. The observed exchange of pentafluorophenyl group attached to boron to hydrogen results in the formation of bis(pentafluorophenyl)borane, which has a strongly reduced ability to activate the Si-H bond. The substitution kinetics were studied by following the disappearance of absorption of the B(C 6 F 5) 3 charge transfer peak in the UV spectrum. Complementary quantum mechanical calculations allowed us to propose a mechanism of the ligand exchange reaction, which involves electrophilic substitution of the pentafluorophenyl group through a four-center transition state. [ABSTRACT FROM AUTHOR]

Three rare-earth oxide selenates Ln 2 O 2 SeO 4 (Ln = La, Pr, Nd) have been prepared via double-exchange solid-state reactions between respective LnOCl oxyhalides and potassium selenate. This approach succeeded to obtain single-phase specimens of La 2 O 2 SeO 4 and Nd 2 O 2 SeO 4 , previously known as transients upon thermal decomposition of the corresponding selenates, as well as a new compound Pr 2 O 2 SeO 4. Refinement of their crystal structures from powder X-ray diffraction data confirmed previous attributions to the grandreefite (Pb 2 F 2 SO 4) structure type observed also for the Ln 2 O 2 SO 4 oxide sulfates. According to polythermic X-ray studies, La 2 O 2 SeO 4 is stable until at least 700 °C. All compounds were characterized by infrared and X-ray photoelectron spectroscopy. Double exchange reactions of rare-earth opxyhalides LnOCl (Ln = La, Pr, Nd) and potassium selenate lead to pure oxide selenates Ln 2 O 2 SeO 4 formerly supposed as transients upon decomposition of Ln 2 (SeO 4) 3 ⋅8H 2 O. Image 1 • Three new Ln 2 O 2 SeO 4 compounds have been prepared (Ln = La, Pr, Nd). • The new compounds are isostructural to Ln 2 O 2 SO 4. • Double-exchange solid-state synthesis is an only approach to these compounds. [ABSTRACT FROM AUTHOR]

A simple green spectrophotometric method was developed and validated for determination of non chromophoric substance; monosodium glutamate (MSG) by its reaction with a metal complexing agent; iron (III) salicylate. The color of the reagent measured at 525 nm fainted with increased absorbance at 299 nm upon addition of MSG, suggesting a ligand exchange reaction. Different parameters that may affect the reaction in the method were investigated such as: iron (III) salicylate concentration, pH, ionic strength and time of the reaction. The developed method was validated according to the guidelines of the International Conference on Harmonization (ICH). The linearity range was 250–2500 µM with correlation coefficient 0.9988. The limits of detection and quantitation were 71.5 µM and 216.76 µM. The developed method was successfully applied for determination of MSG in instant noodles' seasoning and the Chinese salt and statistically compared to a reported HPLC method and good agreement was observed. The method shows advantages over other published spectrophotometric methods and was suitable for routine analysis of MSG in food preparations. • MSG was accurately determined as a food additive in noodles and Chinese salt. • MSG displaced salicylate from iron (III) salicylate through ligand exchange. • The method was green, simple, rapid and more suitable for foodstuff analysis. • The method gave comparable performance to the reported HPLC method. [ABSTRACT FROM AUTHOR]

Radioactive Cs+ is one of the most dangerous environmental pollutants. It is necessary for radioactive Cs+ management and removal. Titanium-type cesium ion sieve with a strong Ti–O bond has the advantages of structural stability, radiation resistance and no secondary contamination, which is a promising adsorbent material. In this paper, The CTO (Cs 2 Ti 6 O 13) is prepared for the first time by sol-gel and de-templating methods, and cesium ion sieves (HTO/PMMA) are further obtained with diluted HCl elution. Compared with the ionic sieves (HTO) prepared by direct sol-gel method, the adsorption capacity is improved from 224.32 mg/g to 299.15 mg/g. The prepared HTO/PMMA has a larger specific surface area (67.282 m2/g). More exchange sites are provided for the adsorption of Cs ions. Moreover, Adsorption involves the cleavage of O–H bonds and the formation of O–Cs bonds, which is a typical ion exchange reaction. A series of batch experiments are carried out. The results showed that the equilibrium adsorption capacity of HTO/PMMA is 307.69 mg/g and remained high in the interfering ion solution as well (280.38 mg/g). The pseudo second order model and Freundlich model can well describe the ion exchange process. Thermodynamic study shows that adsorption is spontaneous and exothermic, and low temperature is conducive to adsorption in H+- Cs+ exchange system. Finally, the reusability of HTO/PMMA is evaluated. The adsorption capacity did not decrease significantly after 5 cycles of use. Therefore, HTO/PMMA is expected to be an excellent material for recovering radioactive Cs+. [Display omitted] • A novel material (HTO/PMMA) for the Adsorption of Cs+. • The HTO/PMMA has a large specific surface area (67.282 m2/g). • The adsorption mechanism involves the cleavage of O–H bonds and the generation of O–Cs bonds. • The adsorption uptake remains 281.94 mg/g after 5 cycles. [ABSTRACT FROM AUTHOR]

Abstract Here we investigated the effect of electrostatic interactions and of protein tyrosine nitration of mammalian cytochrome c on the dynamics of the so-called alkaline transition, a pH- and redox-triggered conformational change that implies replacement of the axial ligand Met80 by a Lys residue. Using a combination of electrochemical, time-resolved SERR spectroelectrochemical experiments and molecular dynamics simulations we showed that in all cases the reaction can be described in terms of a two steps minimal reaction mechanism consisting of deprotonation of a triggering group followed by ligand exchange. The p K a a l k values of the transition are strongly modulated by these perturbations, with a drastic downshift upon nitration and an important upshift upon establishing electrostatic interactions with a negatively charged model surface. The value of p K a a l k is determined by the interplay between the acidity of a triggering group and the kinetic constants for the forward and backward ligand exchange processes. Nitration of Tyr74 results in a change of the triggering group from Lys73 in WT Cyt to Tyr74 in the nitrated protein, which dominates the p K a a l k downshift towards physiological values. Electrostatic interactions, on the other hand, result in strong acceleration of the backward ligand exchange reaction, which dominates the p K a a l k upshift. The different physicochemical conditions found here to influence p K a a l k are expected to vary depending on cellular conditions and subcellular localization of the protein, thus determining the existence of alternative conformations of Cyt in vivo. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Validation of per-deuterated pyruvate for hyperpolarization experiments. • No major kinetic isotope effects observed. • Physiological information obtained about alanine transaminase and compartmentation. • No major effects on HP exam, but line broadening in alanine. Abstract This study was designed to determine the effects of deuteration in pyruvate on exchange reactions in alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and flux through pyruvate dehydrogenase (PDH). Although deuteration of a 13C enriched substrate is commonly used to increase the lifetime of a probe for hyperpolarization experiments, the potential impact of kinetic isotope effects on such substitutions has not been studied in detail. Metabolism of deuterated pyruvate was investigated in isolated rat hearts. Hearts were perfused with a 1:1 mixture of [U-13C 3 ]pyruvate and [2-13C 1 ]pyruvate or a 1:1 mixture of [U-13C 3 ]pyruvate plus [2-13C 1 , U-2H 3 ]pyruvate for 30 min before being freeze clamped. Another set of hearts received [2-13C 1 , U-2H 3 ]pyruvate and was freeze-clamped at 3 min or 6 min. Tissue extracts were analyzed by 1H and 13C{1H} NMR spectroscopy. The chemical shift isotope effect of 2H was monitored in the 13C NMR spectra of the C2 resonance of lactate and alanine plus the C5 of glutamate. There was little kinetic isotope effect of 2H in pyruvate on flux through PDH, LDH or ALT as detected by the distribution of 13C, but the distribution of 2H differed markedly between alanine and lactate. At steady-state, alanine was a mixture of deuterated species, while lactate was largely perdeuterated. Consistent with results at steady-state, hearts freeze-clamped at 3 min or 6 min showed rapid removal of deuterium in alanine but not in lactate. Metabolism of hyperpolarized [1-13C 1 ]pyruvate was compared to [1-13C 1 ,U-2H 3 ]pyruvate in isolated hearts. Consistent with the results from tissue extracts, there was little effect of deuteration on the kinetics of appearance of lactate, alanine or bicarbonate, but there was a small, time-dependent upfield chemical shift in the HP[1-13C 1 ]alanine signal reflecting exchange of methyl deuterons with water protons. Together, these results demonstrate that (1) the kinetics of pyruvate metabolism in hearts detected by 13C NMR are not affected by replacement of the pyruvate methyl protons with deuterons and (2) that the loss of deuterium from the methyl position occurs rapidly during the conversion of pyruvate to alanine. The majority of the deuterium atoms are lost on the time-scale of a hyperpolarization experiment. [ABSTRACT FROM AUTHOR]

Abstract The interaction between oxygen in the gas phase and La 2– x Ca x Zr 2 O 7– α (x = 0; 0.05; 0.1) with a pyrochlore structure was studied by the isotope exchange method with the gas phase equilibration in the temperature range of 600–900 °C and the oxygen pressure of 1.01 kPa. The oxygen diffusion and oxygen surface exchange coefficients were calculated for the investigated oxides. The rate-determining stage of the oxygen surface exchange kinetics for La 1.9 Ca 0.1 Zr 2 O 7– α was found to be different from that for La 1.95 Ca 0.05 Zr 2 O 7– α and La 2 Zr 2 O 7– α. The influence of the calcium content in La 2– x Ca x Zr 2 O 7– α (x = 0; 0.05; 0.1) oxides on the heterogeneous exchange rates and oxygen tracer diffusion coefficients were discussed. Graphical abstract Electron back-scattered diffraction results. fx1 Highlights • The oxygen surface exchange rates are measured in doped lanthanum zirconates. • The oxygen diffusion coefficients are measured in doped lanthanum zirconates. • The calcium segregation process is found in doped lanthanum zirconates. [ABSTRACT FROM AUTHOR]

Highlights • Theory of ligand binding. • Use of radiolabeled and fluorescent ligands. • Label-free techniques for studying receptors. • GTP binding to probe G protein activation. • BRET and FRET to study receptor activation. Abstract Characterisation of receptors can involve either assessment of their ability to bind ligands or measure receptor activation as a result of agonist or inverse agonist interactions. This review focuses on G protein-coupled receptors (GPCRs), examining techniques that can be applied to both receptors in membranes and after solubilisation. Radioligand binding remains a widely used technique, although there is increasing use of fluorescent ligands. These can be used in a variety of experimental designs, either directly monitoring ligand itself with techniques such as fluorescence polarisation or indirectly via resonance energy transfer (fluorescence/Forster resonance energy transfer, FRET and bioluminescence resonance energy transfer, BRET). Label free techniques such as isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) are also increasingly being used. For GPCRs, the main measure of receptor activation is to investigate the association of the G protein with the receptor. The chief assay measures the receptor-stimulated binding of GTP or a suitable analogue to the receptor. The direct association of the G protein with the receptor has been investigated via resonance energy techniques. These have also been used to measure ligand-induced conformational changes within the receptor; a variety of experimental techniques are available to incorporate suitable donors and acceptors within the receptor. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) can serve as potential biological targets for early screening, targeted therapy, and prognosis in ovarian cancer (OC). However, sensitive and reliable quantification and identification of miRNA remain a huge challenge. Herein, we proposed a simple and reliable approach for the ultra-sensitive detection of miRNA by integrating endonuclease-III (Exo-III) assisted signal recycle, primer exchange reaction (PER), and hairpin catalytic reaction (HCR). In this method, target miRNA specifically binds with toehold sequence to form a blunt 3' terminus in the detection probe (dumbbell probe) that can be recognized by Exo-III, and to initiate subsequent signal amplifications. Based on this, the approach is successfully utilized in detecting OC related miRNAs with high sensitivity (limit of detection for miRNA-211 was 13 aM) and stability. By simply changing the toehold sequence in detection probe, the established approach can be easily extended to other miRNA detection. We believe that the platform is robust in detecting OS related biomarkers and is promising in renovating cancer diagnostic tools. [Display omitted] • We proposed a modularized platform for the ultra-sensitive detection of miRNA. • The platform is composed of two module, including a sensing module and a signal amplification module. • The platform was successfully utilized in detecting miRNA-211 with high sensitivity. [ABSTRACT FROM AUTHOR]

The solution-processed quantum dot (QD) solar cell technology has seen significant advancements in recent past to emerge as a potential contender for the next generation photovoltaic technology. In the development of high performance QD solar cell, the surface ligand chemistry has played the important role in controlling the doping type and doping density of QD solids. For instance, lead sulfide (PbS) QDs which is at the forefront of QD solar cell technology, can be made n-type or p-type respectively by using iodine or thiol as the surfactant. The advancements in surface ligand chemistry enable the formation of p-n homojunction of PbS QDs layers to attain high solar cell performances. It is shown here, however, that poor Fermi level alignment of thiol passivated p-type PbS QD hole transport layer with the n-type PbS QD light absorbing layer has rendered the photovoltaic devices from realizing their full potential. Here we develop a control surface oxidation technique using facile ultraviolet ozone treatment to increase the p-doping density in a controlled fashion for the thiol passivated PbS QD layer. This subtle surface modification tunes the Fermi energy level of the hole transport layer to deeper values to facilitate the carrier extraction and voltage generation in photovoltaic devices. In photovoltaic devices, the ultraviolet ozone treatment resulted in the average gain of 18% in the power conversion efficiency with the highest recorded efficiency of 8.98%. [ABSTRACT FROM AUTHOR]

Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) emerged as a tool for biochemistry and structural biology around 25 years ago. It has since become a key approach for studying protein dynamics, protein-ligand interactions, membrane proteins and intrinsically disordered proteins (IDPs). In HDX labeling, proteins are exposed to deuterated solvent (usually D 2 O) for a variable ‘labeling time’, resulting in isotope exchange of unprotected labile protons on the amide backbone and amino acid side chains. By comparing the levels of deuterium uptake in different regions of a protein, information on conformational and dynamic changes in the system can be acquired. When coupled with MS, HDX is suitable for probing allosteric effects in catalysis and ligand binding, epitope mapping, validation of biosimilars, drug candidate screening and mapping membrane-protein interactions among many other bioanalytical applications. This review introduces HDX-MS via a brief description of HDX-MS development, followed by an overview of HDX theory and ultimately an outline of methods and procedures involved in performing HDX-MS experiments. [ABSTRACT FROM AUTHOR]

In photocatalyst designing, quick recombination of photo-generated electron-hole pairs in the bulk or on the surface of semiconductors is a major limiting factor in achieving high photocatalytic efficiency, which is one of the most knotty scientific issues. For this purpose, a series of Cd 1−x Zn x S twin nanocrystal (NC) zinc blende/wurtzite (ZB/WZ) homojunctions photocatalysts were synthesized by a facile solvothermal route and innovatively employed in photocatalytic degradation. In sample Cd 0.6 Zn 0.4 S, ZB and WZ phases have the largest distribution and closest interconnection at atomic level. The type-II staggered band alignment formed between two phases made photo-generated electrons and holes spatially separated to ZB (away from twin plane) and WZ (to twin plane) regions, and the ordered arrangement of redox reaction’s active sites was then realized inside a single semiconductor. Finally, photocatalytic activities of the samples were evaluated by degradation of methylene blue (MB) upon visible light irradiation. The optimal Cd 0.6 Zn 0.4 S NCs without any co-catalyst loading showed high photocatalytic activity with degradation efficiency of 95% in 80 min and performed excellent photostability. Furthermore, photocatalytic degradation and electron transfer mechanisms in Cd 0.6 Zn 0.4 S twin NCs are studied particularly. Inner twin structure homojunction has provided a new insight into the crystalline phase engineering. [ABSTRACT FROM AUTHOR]

Reactions of layered perovskite-like oxides K 2 La 2 Ti 3 O 10 , NaLaTiO 4 and corresponding protonated oxides H 2 La 2 Ti 3 O 10 , HLaTiO 4 with vanadyl sulfate aqueous solution have been studied. It was revealed that the exchange reaction of interlayer alkali cations in K 2 La 2 Ti 3 O 10 and NaLaTiO 4 by with vanadyl cations, which was reported in the literature previously, does not proceed. The formation of the corresponding protonated forms and vanadium-containing particles is found to occur instead. In the case of protonated forms H 2 La 2 Ti 3 O 10 , HLaTiO 4 vanadium-containing nanostructures are formed on the surface. [ABSTRACT FROM AUTHOR]

Hypothesis Ligand exchange is a widely-used method of controlling the surface chemistry of nanomaterials. Exchange is dependent on many factors including the age of the core particle being modified. Aging of the particles can impact surface structure and composition, which in turn can affect ligand binding. Experiments To quantify the effects of aging on ligand exchange, we employed a technique to track the exchange of radiolabeled 14 C-oleic acid with unlabeled, oleic acid bound to iron oxide nanoparticles. Liquid scintillation counting (LSC) was used to determine the amount of 14 C-oleic acid adsorbing to the particles throughout the duration of the exchange for particles aged for 2 days, 7 days, and 30 days. Findings Results revealed an increase in the total amount of ligands exchanged with aging up to 30 days. Kinetic analysis of these results revealed a significant decrease in the overall rate of ligand exchange between 2 and 30 days. The change in extent of adsorption with age could suggest increased availability of free binding sites. A follow-up study comparing exchange with oxidized and unoxidized particles suggested this increase in ligand adsorption may be due to changes in the Fe 2+ /Fe 3+ ratio on the surface as the particles aged. [ABSTRACT FROM AUTHOR]

Low dimensional nanomaterials have emerged as candidates for gas sensors owing to their unique size-dependent properties. In this paper, Bi 2 S 3 nanobelts were synthesized via a facile solvothermal process and spin-coated onto alumina substrates at room temperature. The conductometric devices can even sensitively response to the relatively low concentrations of NO 2 at room temperature, and their sensing performance can be effectively enhanced by the ligand exchange treatment with inorganic salts. The Pb(NO 3 ) 2 -treated device exhibited superior sensing performance of 58.8 under 5 ppm NO 2 at room-temperature, with the response and recovery time of 28 and 106 s. The competitive adsorption of NO 2 against O 2 on Bi 2 S 3 nanobelts, with the enhancement both in gas adsorption and charge transfer caused by the porous network of the very thin Bi 2 S 3 nanobelts, can be a reasonable explanation for the improved performance at room temperature. Their sensitive room-temperature response behaviors combined with the excellent solution processability, made Bi 2 S 3 nanobelts very attractive for the construction of low-cost gas sensors with lower power consumption. [ABSTRACT FROM AUTHOR]

The synthesis and structure determination of atomically precise alloy nanoclusters have attracted much attention in recent research. Herein, we report a new alloy nanocluster Au 24- x Ag x (TBBM) 20 ( x ∼ 1) synthesized via a ligand-exchange-induced size/structure transformation method. Its X-ray structure is obtained successfully and the dopant Ag is found to occupy three special positions in the kernel, rather than equivalently over all the kernel sites. This selective occupancy is interesting and DFT calculation results suggest that the relative oxidation state (rationalized as difference in the charge) of the Ag when doped into the cluster is likely determining the most favorable doping positions. This work provides a new strategy for controlled synthesis of new Au-Ag nanoclusters and also reveals a new scenario for the doping position of Ag atoms in Au-Ag bimetal nanoclusters. [ABSTRACT FROM AUTHOR]

Cations in natural solutions significantly impact interfacial processes, particularly dissolution and surface charge measurements for quartz and silica, which are amongst the most naturally abundant and technologically important solids. Thermodynamic parameters for cation-specific interfacial reactions have heretofore been mostly derived instead of directly measured experimentally. This work investigates the energetics of adsorption and exchange reactions of alkali metal (M + ) and alkaline earth (M 2+ ) cations with the quartz surface by flow adsorption microcalorimetry, in tandem with in-situ pH measurements. The magnitudes of the heats of adsorption and exchange were found to increase along the Hofmeister series i.e., Li + < Na + < K + < Rb + < Cs + and Mg 2+ < Ca 2+ < Sr 2+ < Ba 2+ , and exhibited strong correlations to bulk cation hydration enthalpies (ΔH hyd ). These results suggest inner-sphere adsorption for all studied cations and highlight the role ΔH hyd plays in rationalizing these reactions and controlling their net overall enthalpy. pH measurements demonstrate that quartz surface charge will vary depending on the cation present, as is well known for amorphous forms of silica. Along with calorimetric signals, pH data revealed kinetic differences between the adsorption and desorption reactions of M + and M 2+ , and individual cations within each group. [ABSTRACT FROM AUTHOR]

The Io plasma torus is mostly composed of electrons and ions of O and S, singly and multiply-charged. These ions interact with the neutral species of Io's atmosphere (S, O, SO 2 and SO) through symmetrical (e.g., O+ + O ⇒ O + O+) and asymmetrical (e.g., S+ + O ⇒ S + O+) charge exchange reactions. Moreover, molecular ions (SO 2 +, SO+) produced in Io's atmosphere by ionization or charge exchange are accelerated as they are picked up by the local plasma flow and eventually also charge exchange with the atmospheric neutrals (e.g., SO 2 + + SO 2 ⇒ SO 2 + SO 2 +). Cross sections for many charge exchange reactions were estimated in Johnson and Strobel (1982) and McGrath and Johnson (1989) for ion speeds of 60 km/s appropriate for torus/neutral cloud interactions where the plasma is approximately at corotation in Io's reference frame. But close to Io, the flow velocity and ion temperature are drastically reduced (V flow < 10 km/s and T ion < 50 eV) and greatly increased on its flanks (∼80 km/s and 400 eV). Thus, velocity-dependent charge exchange cross sections are critical for numerical simulations of the Io plasma/atmosphere interaction. We provide estimates of charge exchange cross sections of ions on molecular neutrals and of molecular ions on neutrals for the range of velocity [5–120] km/s representative of ion velocities at Io. We combine several methods valid at the low and higher velocities in this range: Two-state impact parameter approximation, quasi-thermal rate constant extrapolation, Langevin orbiting cross sections and scaling from experimental data. We describe these methods in details. Our estimates at 60 km/s are 2–3 times smaller or larger than previously published values, depending on the reaction. Most are generally large (∼60–90 Å 2) at small velocities. We discuss the most important reactions relevant to Io's interaction and where improvements and experimental values are needed. We anticipate the effect of these velocity-dependent cross sections in numerical simulations of Io's interaction and show that some of these reactions are of critical importance regarding the plasma composition close to Io, the plasma supply to the torus and the neutral supply to Io's corona and to the giant neutral clouds that extend along Io's orbit. • Charge exchange reactions are important in Io's atmosphere/plasma interaction • Charge exchange cross sections depend on ion velocities • We provide new estimates of velocity-dependent cross sections relevant to Io • These cross sections can be easily implemented in Io's local interaction model • Significant consequences for the neutral supply to Io's corona and extended clouds [ABSTRACT FROM AUTHOR]

Sickle hemoglobin (HbS) polymerization initiates in the deoxy state with the binding of hydrophobic patch formed by the isopropyl group of βVal6 residue of a hemoglobin tetramer with the hydrophobic pocket of another tetramer, whose hydrophobic patch binds to the hydrophobic groove of a third molecule. Subsequent elongation of a single stranded polymer followed by the formation of a double strand and finally combination of seven such pairs of double strands results in a fourteen stranded fibrous polymer. Precipitation of this fiber inside the erythrocytes results in sickling of red blood cells. Surprisingly, the polymerization does not occur in the oxy state of HbS. Due to the unavailability of crystal structure of oxy form of HbS, the molecular basis of inhibition of polymerization in the oxy state is unknown to date. In the present study, we have attempted to understand the molecular mechanism of inhibition of polymerization by exploiting the exchange of backbone amide hydrogens of HbS with deuterated solvent. Hydrogen/deuterium exchange kinetics of peptide amide hydrogens of both oxy and deoxy form of HbS were monitored through ESI mass spectrometry. Upon oxygenation changes in the conformational flexibility across different regions of α and β globin chains in the tetrameric HbS molecule were investigated. It was observed that oxygenation led to perturbation in the conformation of several residues around the hydrophobic patch, groove of a tetramer and axial, lateral contacts across the double strands that are involved in HbS polymerization. [ABSTRACT FROM AUTHOR]

Ionothermal reactions of 1,3,5-benzenetricarboxylate acid (H 3 BTC) and Ni(NO 3 ) 2 , Co(NO 3 ) 2 and Cu(NO 3 ) 2 gave two discrete 32-membered ring-like allomers, [M 2 (HBTC) 2 (NH 2 CONH 2 ) 2 (H 2 O) 4 ]·3H 2 O (M=Ni( 1 ), Co( 2 )) and one layered [Cu 2 (BTC)Cl(H 2 O) 4 ] ( 3 ). The weak interactions in 1 can be deconstructed to some degree in ion exchange by exploring the factors of divalent and trivalent metal species, metal concentration and soaking time, which are demonstrated by PXRD and N 2 absorption. Cu 2+ has the highest N 2 adsorbance when soaking with 1 , and 1 can keep structure stable when Cu 2+ below 0.16 mol L −1 and the soaking time within 24d. As Cu 2+ beyond 0.16 mol L −1 and the soaking time beyond 24d, the structure of compound 1 starts to transform with the crystal morphology from clear pale green to opaque blue. Ionothermal reactions of compound 1 with different Cu 2+ amounts obtained Ni 2+ -Cu 2+ hetero complexes, whose PXRD patterns are similar to that of 3 and EDS indicates Cu 2+ % increases with Cu 2+ additions and close to 100% as Cu 2+ being 1.6 mmol. It suggests that 3 is a controlled product and Cu 2+ can transform discrete compound 1 into 2D compound 3 . [ABSTRACT FROM AUTHOR]

New Dion-Jacobson type layered perovskite compounds A'Ln 2 Ti 2 NbO 10 (A′ ​= ​Rb, H; Ln ​= ​Pr, Nd) were synthesized for the first time. The phase and chemical purity of the compounds were proved by X-ray diffraction (XRD) and EDX. Compounds RbPr 2 Ti 2 NbO 10 and RbNd 2 Ti 2 NbO 10 were synthesized using solid-state reactions, whereas HPr 2 Ti 2 NbO 10 ·1.5H 2 O and HNd 2 Ti 2 NbO 10 ·2H 2 O were obtained from Rb-containing phases by ion-exchange reactions. Crystal structures of RbPr 2 Ti 2 NbO 10 (P4/mmm, a ​= ​0.38223 (1) nm, c ​= ​1.51485 (8) nm, R wp ​= ​3.87%) and RbNd 2 Ti 2 NbO 10 (P4/mmm, a ​= ​0.38153 (1) nm, c ​= ​1.51200 (6) nm, R wp ​= ​3.62%) were refined using the Rietveld method. The distortions of polyhedrons in the structures were studied in detail. The thermal behavior of compounds was established using DTA. The ion-exchange products were found to be metastable hydrates. Optical band gap, valence band edge and conduction band edge potentials of obtained compounds were calculated from diffuse reflectance spectroscopy data. Photocatalytic experiment of methylene blue degradation under ultraviolet (UV) light was conducted with ground synthesized compounds. The particle size distributions were measured by laser diffraction before and after grinding. RbNd 2 Ti 2 NbO 10 showed the highest photocatalytic activity, while HPr 2 Ti 2 NbO 10 ·1.5H 2 O and HNd 2 Ti 2 NbO 10 ·2H 2 O showed none. [Display omitted] • Dion-Jacobson phases RbPr 2 Ti 2 NbO 10 , RbNd 2 Ti 2 NbO 10 , ​HPr 2 Ti 2 NbO 10 ·1.5H 2 O and HNd 2 Ti 2 NbO 10 ·2H 2 O were synthesized. • The crystal structures of RbPr 2 Ti 2 NbO 10 and RbNd 2 Ti 2 NbO 10 were refined using the Rietveld method. • Thermal stability of obtained phases was studied using DTA and TGA. • Optical band gaps, valence band and conduction band edges potentials were calculated from diffuse reflectance spectra. • All compound were tested in a reaction of photocatalytic decomposition of methylene blue. RbNd 2 Ti 2 NbO 10 showed highest photocatalytic activity. [ABSTRACT FROM AUTHOR]

Layered and defect layered titanates are a wide class of ion exchangeable and technologically important ceramics. The majority of ion exchange methods employ excess reagents at elevated temperatures often leading to complete exchange. Control over the degree of ion exchange is desirable as this allows composition, structure and properties to be continuously tuned. Here, direct control over the degree of lithiation in the Ruddlesden-Popper n ​= ​3 derived phase H 2 La 2 Ti 3 O 10 , at room temperature using LiOH.H 2 O, is demonstrated. The resulting series H 2-x Li x La 2 Ti 3 O 10 (x ​= ​0, 0.125, 0.25, 0.5, 0.75, 1) can then be dehydrated allowing defect tuning in Li 2x Vac 2-2x La 2 Ti 3 O 9+x defect layered perovskites. Materials containing a mixture of lithium cations and vacant sites often show fast-ion conducting but controlling the ratio has previously proved challenging. The synthesis and degree of exchange is investigated using X-ray powder diffraction data, thermogravimetric analysis and the ionic mobility assessed via a.c. impedance spectroscopy. As use of LiOH.H 2 O has now been shown to directly control ion exchange in both n ​= ​1 and n ​= ​3 phases the possibility of the methodology being applied more generally to layered materials is discussed. Multi-step reactions at ambient temperature afford a quantitative ion-exchange route to new crystalline compounds in the layered perovskite Ruddlesden-Popper family. [Display omitted] • Room temperature, direct & tuneable control of lithiation in protonated layered titanate perovskites and RP3 phases. • Dehydration of partly lithiated compounds allows for control of lithium to vacancy ratio. • Lithium ion conductivity is shown to be affected by A site vacancy: lithium ratio. [ABSTRACT FROM AUTHOR]

Diabetic retinopathy (DR) is a chronic microvascular complication of diabetes mellitus (DM). It is a worldwide growing epidemic disease considered to be the leading cause of vision-loss and blindness in people with DM. Redox reactions occurring at the extra- and intracellular levels are essential for the maintenance of cellular homeostasis. Dysregulation of redox homeostasis are implicated in the onset and development of DR. Thioredoxin1 (TRX1) and Thioredoxin2 (TRX2) are cytoplasmic and mitochondrially localized antioxidant proteins ubiquitously expressed in various cells and control cellular reactive oxygen species (ROS) by reducing the disulfides into thiol groups. Thioredoxin-interacting protein (TXNIP) binds to TRX system and inhibits the active reduced form of TRX through disulfide exchange reaction. Recent studies indicate the association of TRX/TXNIP with redox signal transduction pathways including activation of Nod-like receptor pyrin domain containing protein-3 (NLRP3) inflammasome, apoptosis, autophagy/mitophagy, epigenetic modifications in a redox-dependent manner. Thus, it is important to gain a more in-depth understanding about the cellular and molecular mechanisms that links redoxisome and ER/Mitochondrial dysfunction to drive the progression of DR. The purpose of this review is to provide a mechanistic understanding of the complex molecular mechanisms and pathophysiological roles associated with redoxisome, the TRX/TXNIP redox signaling complex under oxidative stress in the development of DR. Also, the molecular targets of FDA approved drugs and clinical trials in addition to effective antioxidant strategies for the treatment of diabetic retinopathy are reviewed. [Display omitted] • Hyperglycemia mediated oxidative stress promotes redoxisome activation in the retina. • Disruption of the cellular homeostasis by redoxisomal signaling complex contributes to the pathogenesis of diabetic retinopathy. • TXNIP activates NLRP3 inflammasome which promotes retinal apoptosis and inflammation. • TXNIP/NLRP3 under oxidative stress triggers signaling cascades associated with ER stress and mitochondrial dysfunction in retina. • TXNIP plays an essential role in epigenetic alterations associated with retinopathy. • TXNIP can be a potential therapeutic target for the management of diabetic retinopathy. [ABSTRACT FROM AUTHOR]

Oxygen surface exchange properties of lanthanum nickelates La 2 NiO 4+δ , La 3 Ni 2 O 7-δ and La 4 Ni 3 O 10-δ (LNOs) have been investigated using the Pulsed Isotope 18O/16O Exchange (PIE) technique in the temperature range 300–700 ​°C. The evaluation of the oxygen exchange rate from these lanthanum nickelates was conducted by measurement of isotope fractions 18O 2 , 16O18O, and 16O 2 in the effluent pulse at the exhaust from the reactor with a packed bed. The rates of oxygen heterogenous surface exchange (r H), dissociative adsorption (r a) and incorporation (r i) were calculated. The oxygen surface exchange was found to vary between the three nickelates, with r H decreasing between samples La 3 Ni 2 O 7-δ ​> ​La 4 Ni 3 O 10-δ ​> ​La 2 NiO 4+δ , which was attributed to a decreasing presence of Ni cations on the particle surfaces. Despite possessing the lowest oxygen surface exchange, La 2 NiO 4+δ had the best electrode electrochemical performance, which was attributed to highly mobile interstitial oxygen atoms leading to the largest r i (surface oxygen incorporation rate into the bulk) of the nickelates. This study reveals the key limiting factors determining lanthanum nickelate cathode performance in SOFCs, and we suggest avenues to improve these materials towards functional cathodes in devices. [Display omitted] • La 2 NiO 4 oxygen surface exchange is limited by dissociative adsorption of oxygen. • For La 3 Ni 2 O 7 , La 4 Ni 3 O 10 oxygen surface exchange is limited by oxygen incorporation. • Low presence of Ni on the particle surfaces decreases oxygen surface exchange rate. [ABSTRACT FROM AUTHOR]

Shrub encroachment, a common occurrence in drylands over the past 150 years, has the potential to alter the redistribution of soil and soil resources by wind and water. This may affect decomposition via soil-litter mixing (SLM). SLM can accelerate decomposition, but its contributions and relationship with abiotic controls, particularly in the context of shrub encroachment, are unknown. To better understand the spatiotemporal relationships between decomposition and shrub encroachment, we conducted a 24 month decomposition study aimed at understanding how placement of litter on either up or downwind sides of dunes in association dune volume affected litter decomposition. There was little decomposition in the first six months of the experiment, with 97.2% of mass remaining despite high exposure to solar radiation. Decay occurred in synchrony with monsoons and SLM, suggesting precipitation during the monsoon season plays an important role in facilitating both SLM and decomposition. Litter placements across a gradient of shrub volumes had no effect on decomposition rates and SLM, but litter placement on the downwind side of dunes had a positive influence on soil-microbial film development. Ultimately, monsoons rainfall and SLM promoted decomposition across a gradient of shrub encroachment in this dryland ecosystem. [ABSTRACT FROM AUTHOR]

Extension of the aluminothermal exchange reaction synthesis of M n +1 AX n phases to systems where the element ‘ A ’ is not the reducing agent was investigated in systems TiO 2 – A –Al–C for A =Al, Si, Ga, Ge, In and Sn as well as Cr 2 O 3 –Ga–Al–C. MAX phase-Al 2 O 3 composites were made in all systems except those with A =Ga or In. The effectiveness of conversion to MAX phases was generally in the range 63–96% without optimisation of starting ratios. Optimisation in the Ti–Si–C system gave a MAX phase component with >98% Ti 3 SiC 2 . [ABSTRACT FROM AUTHOR]

With tuning the ligands from bte, btp, btb to bth, four new decavanadate-based metal–organic hybrid compounds, [Zn(bte)(H 2 O) 4 ][Zn 2 (bte)(H 2 O) 10 ](V 10 O 28 )·8H 2 O, [Zn 2 (btp) 4 (H 2 O) 6 ](H 2 V 10 O 28 )·4H 2 O, [Zn(H 2 O) 6 ][Zn 2 (btb) 2 V 10 O 28 (H 2 O) 6 ]·4H 2 O, and [Zn 2 (bth)(H 2 O) 10 ](H 2 V 10 O 28 )·6H 2 O (bte=1,2-bis(1,2,4-triazol-1-yl)ethane, btp=1,3-bis(1,2,4-triazol-1-y1)propane, btb=1,4-bis(1,2,4-triazol-1-y1)butane, bth=1,6-bis(1,2,4-triazol-1-y1)hexane), have been synthesized under conventional conditions. The four compounds represent the first examples of decavanadate-based metal–organic hybrids constructed by Zn–bis(triazole) complexes. Their structural analyses show that the four compounds possess different Zn–bis(triazole) structural motifs and various finally structures, which verifies that regular changing the spacers of ligands is an effective strategy to tuning the structures of polyoxometalate-based hybrids. Also, the electrochemical studies show that the compounds have good electrocatalytic activities towards oxidation of nitrite molecules ascribed to V-centers. [ABSTRACT FROM AUTHOR]