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An investigation is conducted on chemiluminescence (CL) of CdTe nanocrystals (NCs) induced by directly chemical oxidation and its size-depended surfactant-sensitized effect in aqueous solution. Results indicated that CdTe NCs could be directly oxidized to produce strong CL emission in basic conditions, especially by hydrogen peroxide and potassium permanganate oxidants.

A solution-based synthesis of monodisperse [Cu.sub.2]O nanocrystals with controllable sizes in the nanoscale regime is described and two types nanocrystals, cubes and rhombic dodecahedra unifaceted with either {001} or {110} crystal planes, are prepared. A greater depletion layer of carrier and a relatively small contact potential has accounted for the sensing enhancement in the sensors made from the organized [Cu.sub.2]O nanocrystals.

The fabrication of a new type of nanostructured zinc oxide (ZnO) is used to show a new wet synthetic scheme for architecture of asymmetric nanomaterials via solution processes. This synthetic architecture should be applicable to other II-VI compound semiconductors through stabilizing two or more sets of crystallographic planes in solution media.

Electrochemical surface plasmon resonance (EC-SPR) and electrochemical quartz crystal microbalance (EQCM) are employed to study the redox-induced orientation change of 11-ferrocenylundecanethiol self-assembled monolayers (FcC11SH) (SAM) in two electrolyte solutions. It is seen that the tandem use of EC-SPR and EQCM is an attractive approach for delineating the various redox-triggered surface processes of FcF11SH SAMs.

Removal of hexanal via a post-plasma catalysis system over a Co-Mn solid solution at ambient temperature and pressure was investigated in this study. Results showed that CoMn(9/1) prepared by a citric acid method exhibited the best catalytic activity, which could be ascribed to the higher redox property. Moreover, the coprecipitation method was applied and improved CO2 selectivity significantly, which could be due to smaller grain size, larger surface area, and higher oxygen storage capacity. The reaction pathway and intermediates were analyzed by in situ Fourier transfrom infrared spectroscopy. In addition, results indicated that the removal of hexanal included direct decomposition by plasma and further oxidation of intermediates on the catalyst surface. Furthermore, it could be inferred that the intermediates were further oxidized by the synergistic effect between active oxygen species and catalyst and that the utilization of ozone was the key point in the process. [ABSTRACT FROM AUTHOR]

Hydrothermal reaction of Co(NO3)2 and terphenyl-3,2",5",3'-tetracarboxyate (H4tpta) generated Co3(OH)2 chains based 3D coordination framework Co3(OH)2(tpta)(H2O)4 (1) that suffered from single-crystal-to-single-crystal dehydration by heating at 160 °C and was transformed into dehydrated Co3(OH)2(tpta) (1a). During the dehydration course, the local coordination environment of part of the Co atoms was transformed from saturated octahedron to coordinatively unsaturated tetrahedron. Heterogenous catalytic experiments on allylic oxidation of cyclohexene show that dehydrated 1a has 6 times enhanced catalytic activity than as-synthesized 1 by using tert-butyl hydroperoxide (t-BuOOH) as oxidant. The activation energy for the oxidation of cylcohexene with 1a catalyst was 67.3 kJ/mol, far below the value with 1 catalysts, which clearly suggested that coordinatively unsaturated CoII sites in 1a have played a significant role in decreasing the activation energy. It is interestingly found that heterogeneous catalytic oxidation of cyclohexene in 1a not only gives the higher conversion of 73.6% but also shows very high selectivity toward 2-cyclohexene-1-one (ca. 64.9%), as evidenced in high turnover numbers (ca. 161) based on the open Co(II) sites of 1a catalyst. Further experiments with a radical trap indicate a radical chain mechanism. This work demonstrates that creativity of coordinatively unsaturated metal sites in MOFs could significantly enhance heterogeneous catalytic activity and selectivity. [ABSTRACT FROM AUTHOR]

Magnetically separable millimeter-sizedchitosan beads containingnanosized γ-Fe2O3were prepared for Cr(VI)removal. The magnetism of the beads arises from the γ-Fe2O3nanoparticles, by which the sorbent can be easilyrecovered by the application of an external magnetic field. Variousfactors influencing the sorption behavior such as pH, temperature,contact time, initial concentration of Cr(VI), and coexisting anionswere systematically studied. The time-dependent Cr(VI) sorption datawere well described by pseudo-second-order kinetic model. The bestinterpretation for the equilibrium data was the Freundlich isotherm,and the maximum sorption capacity achieved was 106.5 mg/g at an initialconcentration of 200 ppm and pH 5. Thermodynamic parameters of thesorption process were also calculated, which revealed that the sorptionof Cr(VI) onto γ-Fe2O3–chitosanbeads was spontaneous and exothermic. The sorbed Cr(VI) can be effectivelyremoved from the sorbent with 0.1 M NaOH. The regeneration of thesorbents was affirmed in six sequential cycles of sorption–desorptionexperiments, without significant loss in sorption capacity. Furthermore,Cr(VI) loaded sorbent was investigated by means of FTIR and XPS analysisto discuss the uptake mechanism. The uptake mechanism including electrostaticinteraction, chelation, and precipitation were found to be involvedin the complex sorption of Cr(VI) on the sorbent. [ABSTRACT FROM AUTHOR]

In recent decades, electrochemical detection of arsenic(III) has been undergoing revolutionary developments with higher sensitivity and lower detection limit. Despite great success, electrochemical detection of As(III) still depends heavily on noble metals (predominantly Au) in a strong acid condition, thus increasing the cost and hampering the widespread application. Here, we report a disposable platform completely free from noble metals for electrochemical detection of As(III) in drinking water under nearly neutral condition by square wave anodic stripping voltammetry. By combining the high adsorptivity of Fe3O4 microspheres toward As(III) and the advantages of room temperature ionic liquid (RTIL), the Fe3O4-RTIL composite modified screen-printed carbon electrode (SPCE) showed even better electrochemical performance than commonly used noble metals. Several ionic liquids with different viscosities and surface tensions were found to have a different effect on the voltammetric behavior toward As(III). Under the optimized conditions, the Fe3O4-RTIL composites offered direct detection of As(III) within the desirable range (10 ppb) in drinking water as specified by the World Health Organization (WHO), with a detection limit (3σ method) of 8 × 10-4 ppb. The obtained sensitivity was 4.91 μA ppb-1, which is the highest as far as we know. In addition, a possible mechanism for As(III) preconcentration based on adsorption has been proposed and supported by designed experiments. Finally, this platform was successfully applied to analyzing a real sample collected from Inner Mongolia, China. [ABSTRACT FROM AUTHOR]

A synthetic approach has been devised to convert conventionalStöber silica (SiO2) spheres into a new type ofporous structural platform for supporting multicomponent catalysts.With this approach, we have first prepared zinc-doped SiO2(Zn-SiO2) hollow spheres, on which zinc oxide (ZnO) phaseand ruthenium (Ru) nanoparticles have been deposited and assembledsequentially in solution phase. A series of complex Ru/ZnO/Zn-SiO2nanocatalysts has been thus been integrated onto the zinc-dopedSiO2supports after additional thermal treatment and reduction.To test their workability under harsh reactive environments, we havefurther evaluated the above prepared catalysts using arene hydrogenationas model reactions. These integrated nanocatalysts have shown superioractivity, high robustness, and easy recovery in the studied heterogeneouscatalysis. [ABSTRACT FROM AUTHOR]

The mechanism of amine oxidation catalyzed by D-arginine dehydrogenase (DADH) has been investigated using steady-state and rapid reaction kinetics, with pH, substrate and solvent deuterium kinetic isotope effects (KIE) as mechanistic probes, and computational studies. Previous results showed that 85-90% of the flavin reduction reaction occurs in the mixing time of the stopped-flow spectrophotometer when arginine is the substrate, precluding a mechanistic investigation. Consequently, leucine, with slower kinetics, has been used here as the flavinreducing substrate. Free energy calculations and the pH profile of the Kd are consistent with the enzyme preferentially binding the zwitterionic form of the substrate. Isomerization of the Michaelis complex, yielding an enzyme-substrate complex competent for flavin reduction, is established due to an inverse hyperbolic dependence of kcat/Km on solvent viscosity, Amine deprotonation triggers the oxidation reaction, with cleavage of the substrate NH and CH bonds occurring in an asynchronous fashion, as suggested by the multiple deuterium KIE on the rate constant for flavin reduction (kred). A pKa of 9.6 signifies the ionization of a group that facilitates fiavin reduction in the unprotonated form. The previously reported high-resolution crystal structures of the iminoarginine and iminohistidine complexes of DADH allow us to propose that Tyr53, on a mobile loop covering the active site, may participate in substrate binding and facilitate fiavin reduction. [ABSTRACT FROM AUTHOR]

In this work, we describe a solution-based synthesis of monodisperse Cu20 nanocrystals with controllable sizes in the nanoscale regime. Two types of nanocrystals, cubes and rhombic dodecahedra unifaceted with either {001} or {110} crystal planes, have been prepared at a 100% morphological yield. In particular, synthetic parameters and formation processes of the Cu20 nanocrystals have been investigated in detail, and a range of well-oriented supercrystals/superlattices built from the two types of nanobuilding blocks have been attained for the first time. It has been revealed that n-hexadecylamine used in the present work plays multiple roles: it serves as a chelating ligand to form [Cu(NH2C16H33)4]2+ complex precursor, as a phase-transferring agent to transfer divalent Cu2+ ions into the organic phase, as a reducing agent to generate monovalent Cu+ (i.e., Cu20), as a passivating adsorbate to control crystal morphology, and as a surface capping agent to generate self-assemblies of nanocrystals via van der Waals interaction. Apart from synthesis and self-assembly, disassembly and reassembly of Cu20 nanocrystals have also been investigated. The disassembly processes are accompanied with aggregative growths of nanocrystals, which can be attributed to a combined process of "oriented attachment" and Ostwald ripening, leading to permanent engagement and enlargement of nanocrystals. Finally, our self-assembled nanocrystals of Cu2O show a lower detection limit, lower operating temperature, and higher sensitivity in ethanol vapor detection, compared with other Cu20-based alcohol sensors reported in the recent literature. A greater depletion layer of carrier and a relatively small contact potential may account for the observed sensing enhancement in the sensors made from the organized Cu2O nanocrystals. [ABSTRACT FROM AUTHOR]

The transfer of chirality from molecules to synthesized nanomaterials has recently attracted significant attention. Although most studies have focused on graphene and plasmonic metal nanostructures, layered transition metal dichalcogenides (TMDs), particularly MoS 2 , have recently garnered considerable attention due to their semiconducting and electrocatalytic characteristics. Herein, we report a new approach for the synthesis of chiral molybdenum sulfide nanomaterials based on a bottom-up synthesis method in the presence of chiral cysteine enantiomers. In the synthesis process, molybdenum trioxide and sodium hydrosulfide serve as molybdenum and sulfur sources, respectively. In addition, ascorbic acid acts as a reducing agent, resulting in the formation of zero-dimensional MoS 2 nanodots. Moreover, the addition of cysteine enantiomers to the growth solutions contributes to the chirality evolution of the MoS 2 nanostructures. The chirality is attributed to the cysteine enantiomer-induced preferential folding of the MoS 2 planes. The growth mechanism and chiral structure of the nanomaterials are confirmed through a series of characterization techniques. This work combines chirality with the bottom-up synthesis of MoS 2 nanodots, thereby expanding the synthetic methods for chiral nanomaterials. This simple synthesis approach provides new insights for the construction of other chiral TMD nanomaterials with emerging structures and properties. More significantly, the as-formed MoS 2 nanodots exhibited highly defect-rich structures and chiroptical performance, thereby inspiring a high potential for emerging optical and electronic applications.

Zwitterionic thiolate ligands have the potential to introduce novel assembly modes and functions for noble metal clusters. However, their utilization in the synthesis of silver clusters remains understudied, particularly for the clusters containing reductive Ag(0) species. In this article, we report the first synthesis of a mixed-valence silver(0/I) cluster protected by zwitterionic Tab as thiolate ligands (Tab = 4-(trimethylammonio)benzenethiolate), denoted as [Ag 22 (Tab) 24 ](PF 6 ) 20 ·16CH 3 OH·6Et 2 O ( Ag 22 ·16CH 3 OH·6Et 2 O), alongside an Ag(I) cluster [Ag 20 (Tab) 12 (PhCOO) 10 (MeCN) 2 (H 2 O)](PF 6 ) 10 ·11MeCN ( Ag 20 ·11MeCN). Ag 22 has a distinct hierarchical supratetrahedral structure with a central {Ag 6 } kernel surrounded by four [Ag 4 (Tab) 6 ] 4+ units. High-resolution electrospray ionization mass spectra demonstrate that Ag 22 has two free electrons, indicating a superatomic core. Ag 20 has a drum-like [Ag 12 (Tab) 6 (PhCOO) 6 (H 2 O)] 6+ inner core capped by two tetrahedral-like [Ag 4 (Tab) 3 (PhCOO) 2 (MeCN)] 2+ units. Ag 20 can be transformed into Ag 22 after its reaction with NaBH 4 in solution. Antibacterial measurements reveal that Ag 22 has a significantly lower minimum inhibitory concentration than that of the Ag 20 cluster. This work not only extends the stabilization of silver(0/I) clusters to neutral thiol ligands but also offers new materials for the development of novel antibacterial materials.

Insect gustatory receptors (GRs) aid in the precise identification of deterrent or stimulant compounds associated with food, mating, and egg-laying. Thus, they are promising targets for developing efficient insecticides. Here, 61 GRs in the chemosensory organs of Spodoptera litura larvae and adults were identified. Among them, SlitGR206 exhibited larval labium (LL)-specific expression characteristics. To explore the role of SlitGR206 , a bacterial expression system was established to produce high-quality double-stranded RNA (dsRNA) and suppress SlitGR206 expression in LL. Subsequent behavioral assessments revealed that SlitGR206 silencing influenced larval feeding preferences and absorption. Moreover, it was found to reduce the ability of larvae to forage the five crucial host odorants. These findings demonstrate that SlitGR206 likely plays an indirect regulatory role in host recognition, consequently affecting foraging behavior. This provides a crucial foundation for the analysis of functional diversity among insect GRs and the precise development of nucleic acid pesticides in the future.

A visible-light-induced chemodivergent synthesis of tetracyclic quinazolinones and 3-iminoisoindoliones has been developed. This chemodivergent reaction afforded two kinds of different products by substrate control. A detailed investigation of the reaction mechanism revealed that this consecutive photoinduced electron transfer (ConPET) cascade cyclization involved a radical process, and the aryl radical was the crucial intermediate. This method employed 4-DPAIPN as a photocatalyst and i -Pr 2 NEt as a sacrificial electron donor leading to metal-free conditions.

Caffeic acid (CA), a natural phenolic compound, has important medicinal value and market potential. In this study, we report a metabolic engineering strategy for the biosynthesis of CA in Candida glycerinogenes using xylose and glucose. The availability of precursors was increased by optimization of the shikimate (SA) pathway and the aromatic amino acid pathway. Subsequently, the carbon flux into the SA pathway was maximized by introducing a xylose metabolic pathway and optimizing the xylose assimilation pathway. Eventually, a high yielding strain CG19 was obtained, which reached a yield of 4.61 mg/g CA from mixed sugar, which was 1.2-fold higher than that of glucose. The CA titer in the 5 L bioreactor reached 431.45 mg/L with a yield of 8.63 mg/g of mixed sugar. These promising results demonstrate the great advantages of mixed sugar over glucose for high-yield production of CA. This is the first report to produce CA in C. glycerinogenes with xylose and glucose as carbon sources, which developed a promising strategy for the efficient production of high-value aromatic compounds.

Widespread use of organophosphorus flame retardants (OPFRs) and their ubiquity in water results in the need for a robust and reliable monitoring technique to better understand their fate and environmental impact. In situ passive sampling using the diffusive gradients in thin-films (DGT) technique provides time-integrated data and is developed for measuring OPFRs here. Ultrasonic extraction of binding gels in methanol provided reliable recoveries for all tested OPFRs. Diffusion coefficients of TCEP, TCPP, TDCPP, TPrP, TBP, and TBEP in the agarose diffusive gel (25 °C) were obtained. The capacity of an HLB binding gel for OPFRs was >115 μg per disc, and the binding performance did not deteriorate with time up to 131 days. DGT performance is independent of typical environmental ranges of pH (3.12-9.71), ionic strength (0.1-500 mmol L -1 ), and dissolved organic matter (0-20 mg L -1 ), and also of diffusive layer thickness (0.64-2.14 mm) and deployment time (3-168 h). Negligible competition effects between OPFRs was found. DGT-measured concentrations of OPFRs in a wastewater treatment plant (WWTP) effluent (12-16 days) were comparable to those obtained by grab sampling, further verifying DGT's reliability for measuring OPFRs in waters.

Although the regulation of function of proteins by allosteric interactions has been identified in many subcellular processes, molecular switches are also known to induce long-range conformational changes in proteins. A less well understood molecular switch involving cis-trans isomerization of a peptidyl-prolyl bond could induce a conformational change directly to the backbone that is propagated to other parts of the protein. However, these switches are elusive and hard to identify because they are intrinsic to biomolecules that are inherently dynamic. Here, we explore the conformational dynamics and free energy landscape of the SH2 domain of interleukin-2-inducible T-cell or tyrosine kinase (ITK) to fully understand the conformational coupling between the distal cis-trans molecular switch and its binding pocket of the phosphotyrosine motif. We use multiple microsecond-long all-atom molecular dynamics simulations in explicit water for over a total of 60 μs. We show that cis-trans isomerization of the Asn286-Pro287 peptidyl-prolyl bond is directly coupled to the dynamics of the binding pocket of the phosphotyrosine motif, in agreement with previous NMR experiments. Unlike the cis state that is localized and less dynamic in a single free energy basin, the trans state samples two distinct conformations of the binding pocket-one that recognizes the phosphotyrosine motif and the other that is somewhat similar to that of the cis state. The results provide an atomic-level description of a less well understood allosteric regulation by a peptidyl-prolyl cis-trans molecular switch that could aid in the understanding of normal and aberrant subcellular processes and the identification of these elusive molecular switches in other proteins.

A facile synthesis of novel urchin-like NiCo2O4 hierarchical hollow microspheres has been developed based on a template-free solvothermal and subsequent calcination method. The growth process of NiCo2O4 hollow microsphere precursors has been investigated, and a plausible mechanism was proposed. Because of their unique structure and high specific surface area, these NiCo2O4 hollow microspheres displayed enhanced electrochemical properties in methanol electrooxidation and determination of heavy-metal ions compared with solid urchin-like NiCo2O4 microspheres, Co3O4, and NiO microspheres. The good electrochemical performances suggested that these unique hierarchical NiCo2O4 hollow microspheres could be promising materials for energy and environmentally related applications.

A novel patterning-adsorption-plating process to additively fabricate copper patterns is developed. Functional ink with ion-adsorption nanoparticles was inkjet printed on PET substrate to form the patterned adsorption film. Catalytic ion was adsorbed by amino groups in the adsorption film, and catalyzed the electroless plating of copper. The mercapto groups introduced to the film enhance the reliability of the patterns. Specific solvent used in the ink increase the surface roughness of the adsorption film, leading to a better adhesion of the patterns. The prepared copper patterns show excellent conductivity about the same with bulk copper and good adhesion on PET.

In recent decades, electrochemical detection of arsenic(III) has been undergoing revolutionary developments with higher sensitivity and lower detection limit. Despite great success, electrochemical detection of As(III) still depends heavily on noble metals (predominantly Au) in a strong acid condition, thus increasing the cost and hampering the widespread application. Here, we report a disposable platform completely free from noble metals for electrochemical detection of As(III) in drinking water under nearly neutral condition by square wave anodic stripping voltammetry. By combining the high adsorptivity of Fe3O4 microspheres toward As(III) and the advantages of room temperature ionic liquid (RTIL), the Fe3O4-RTIL composite modified screen-printed carbon electrode (SPCE) showed even better electrochemical performance than commonly used noble metals. Several ionic liquids with different viscosities and surface tensions were found to have a different effect on the voltammetric behavior toward As(III). Under the optimized conditions, the Fe3O4-RTIL composites offered direct detection of As(III) within the desirable range (10 ppb) in drinking water as specified by the World Health Organization (WHO), with a detection limit (3σ method) of 8 × 10(-4) ppb. The obtained sensitivity was 4.91 μA ppb(-1), which is the highest as far as we know. In addition, a possible mechanism for As(III) preconcentration based on adsorption has been proposed and supported by designed experiments. Finally, this platform was successfully applied to analyzing a real sample collected from Inner Mongolia, China.

This work described the preparation, characterization, and electrochemical behavior toward heavy metal ions of the AlOOH-reduced graphene oxide nanocomposites. This new material was synthesized through a green one-pot hydrothermal method. The morphologic and structure of the nanocomposites were characterized using atomic force microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoemission spectroscopy, Fourier transform-infrared spectroscopy, and transmission electron microscopy. Electrochemical properties were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The chemical and electrochemical parameters that have influence on deposition and stripping of metal ions, such as pH value, deposition potential, and deposition time, were also studied. Due to the strong affinity of AlOOH to heavy metal ions and the fast electron-transfer kinetics of graphene, the combination of solid-phase extraction and stripping voltammetric analysis allowed fast and sensitive determination of Cd(II) and Pb(II) in drinking water, making these new nanocomposites promising candidates for practical applications in the fields of detecting heavy metal ions. Most importantly, these new nanocomposites may possess many unknown properties waiting to be explored.