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Subnanocluster (SNC) cocatalysts are considered to be promising cocatalysts for photocatalytic hydrogen evolution reaction (HER) due to their rich surface-active sites and high atom utilization efficiency. Herein, a reductant-mediated in situ growth of the atomic clusters procedure is developed to synthesize SNC-Cu serving as advanced cocatalysts on TiO2 nanoparticles for HER. The optimized SNC-Cu/TiO2 catalyst, with 1.8 wt % metal mass loading, exhibits a remarkable hydrogen evolution rate of 6832 μmol g–1 h–1, which is ca. 25-fold that of bare TiO2 (273 μmol g–1 h–1 and comparable to that of 1 wt % Pt-modified TiO2 (7754 μmol g–1 h–1). Meanwhile, decent photostability and recyclability are also certified via a 20 h durability test. Comprehensive electron microscopy and spectroscopy characterizations unveil that the outstanding performance of SNC-Cu/TiO2 can be attributed to accelerated charge separation/transfer and suppressed photoinduced electron–hole recombination. Furthermore, in situ X-ray photoelectron spectroscopy and first-principle calculations reveal that the electron-localized SNC-Cu, with its abundant surface sites, facilitates *H adsorption and desorption, thus enhancing the HER activity significantly. This work highlights the promising potential of constructing noble-metal-free SNCs in semiconductors for photocatalytic HER. [ABSTRACT FROM AUTHOR]

A series of luminescent dinuclear gold(I) complexes with different crown ether pendants and their related crown-free complexes are synthesized. Findings show that the crown ether-containing gold(I) complexes show specific binding abilities toward various metal cations according to the ring size of the crown pendants.

[sup.2.H] and [sup.15.N] solid-state NMR spectroscopic techniques are used to investigate the side chain and backbone dynamics of wild-type phospholamban (WT-PLB). The NMR data indicates the significant backbone motion for the cytoplasmic domain of WT-PLB when compared to the transmembrane section.

An 18-residue peptide, KWGAKIKGAKIKIGAKI-NH2 is designed to form amphiphilic beta-sheet structures when bound to lipid bilayers. The peptide possesses high antimicrobial activity when compared to naturally occurring linear antimicrobial peptides, most of which adopt an amphipathic alpha-helical conformation upon binding to the lipids.

A series of platinum(II) terpyridyl alkynyl complexes are derivitalized with basic amino functionalities, are synthesized and characterized. The abilities of the complexes to function as colorimetric and luminescence pH sensors were demonstrated with dramatic color changes and luminescence enhancement upon introduction of acid.

Orthorhombic lepidocrocite-type lithium titanate hydrates (LTH), as one important member among two-dimensional (2D) materials, have drawn much attention due to their potential applications in nanoelectronics, energy conversion, and energy storage devices. However, only a few efforts have focused on an anisotropic growth mechanism that determines the formation kinetics of LTH and/or even their derivatives. In this context, in situ Raman observation was employed to the isothermal crystallization of LTH nanosheet crystals from amorphous precursor precipitates. During isothermal crystallization, the formation of monolayered LTH nuclei is controlled by oxygen diffusion with an activation energy of 0.72 eV; anisotropic growth along (010) planes induces an interblocking effect among LTH nanosheet crystals, which limits their size up to 50 nm. The nucleation-growth crystallization kinetics of LTH nanosheets were accurately interpreted by the modified Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, which considered their anisotropic 2D growth. Beyond LTH, the present study that combines in situ spectroscopic monitoring with kinetic modeling paves the way toward deeper comprehension and ultimate control of the growth kinetics of 2D titanate materials. [ABSTRACT FROM AUTHOR]

Microbial methylation and demethylation are two competing processes controlling the net production and bioaccumulation of neurotoxic methylmercury (MeHg) in natural ecosystems. Although mercury (Hg) methylation by anaerobic microorganisms and demethylation by aerobic Hg-resistant bacteria have both been extensively studied, little attention has been given to MeHg degradation by anaerobic bacteria, particularly the iron-reducing bacterium Geobacter bemidjiensis Bem. Here we report, for the first time, that the strain G. bemidjiensis Bem can mediate a suite of Hg transformations, including Hg(II) reduction, Hg(0) oxidation, MeHg production and degradation under anoxic conditions. Results suggest that G. bemidjiensis utilizes a reductive demethylation pathway to degrade MeHg, with elemental Hg(0) as the major reaction product, possibly due to the presence of genes encoding homologues of an organomercurial lyase (MerB) and a mercuric reductase (MerA). In addition, the cells can strongly sorb Hg(II) and MeHg, reduce or oxidize Hg, resulting in both time and concentration-dependent Hg species transformations. Moderate concentrations (10-500 μM) of Hg-binding ligands such as cysteine enhance Hg(II) methylation but inhibit MeHg degradation. These findings indicate a cycle of Hg methylation and demethylation among anaerobic bacteria, thereby influencing net MeHg production in anoxic water and sediments. [ABSTRACT FROM AUTHOR]

Identifying the structure of electrodes at atomic-scale remains a key challenge but is a fertile realm for groundbreaking fundamental research in the advanced Li-ion battery material field. In this context, the subtle structure evolution taking place during lithiation/delithiation in the bulk/surface of Li4Ti5O12 spinel (LTO) was probed using scanning transmission electron microscopy and found to undergo significant structure torque, namely Ti-- O bond stretching/shrinking at different state-of-charge (SOC), which is not identified previously. This kind of nanostructure change plays an important role in facilitating the formation of capturing centers for the electron/hole pairs in a 3.80 eV insulating material as is LTO. Furthermore, with the aid of electron energy loss spectroscopy, the spontaneous charge transfer process, Ti3+ ↔ e- + Ti4+, was confirmed in the fully lithiated Li7Ti5O12 surface as an essential step of the gas-releasing phenomenon. This new insight paves the way toward deeper comprehension and ultimately control of the electrochemical process for this and other important Li-ion battery materials. [ABSTRACT FROM AUTHOR]

The conditions present during enamel crystallite development change dramatically as a function of time, including the pH, protein concentration, surface type, and ionic strength. In this work, we investigate the role that two of these changing conditions, pH and ionic strength, have in modulating the interaction of the amelogenin, LRAP, with hydroxyapatite (HAP). Using solid-state NMR dipolar recoupling and chemical shift data, we investigate the structure, orientation, and dynamics of three regions in the N-terminus of the protein: L15 to V19, V19 to L23, and K24 to S28. These regions are also near the only phosphorylated residue in the protein pS16; therefore, changes in the LRAP-HAP interaction as a function of phosphorylation (LRAP(-P) vs LRAP(+P)) were also investigated. All of the regions and conditions studied for the surface immobilized proteins showed restricted motion, with indications of slightly more mobility under all conditions for L15(+P) and K24(-P). The structure and orientation of the LRAP-HAP interaction in the N-terminus of the phosphorylated protein is very stable to changing solution conditions. From REDOR dipolar recoupling data, the structure and orientation in the region L15V19(+P) did not change significantly as a function of pH or ionic strength. The structure and orientation of the region V19L23(+P) were also stable to changes in pH, with the only significant change observed at high ionic strength, where the region becomes extended, suggesting this may be an important region in regulating mineral development. Chemical shift studies also suggest minimal changes in all three regions studied for both LRAP(-P) and LRAP(+P) as a function of pH or ionic strength, and also reveal that K24 has multiple resolvable resonances, suggestive of two coexisting structures. Phosphorylation also alters the LRAP-HAP interface. All of the three residues investigated (L15, V19, and K24) are closer to the surface in LRAP(+P), but only K24S28 changes structure as a result of phosphorylation, from a random coil to a largely helical structure, and V19L23 becomes more extended at high ionic strength when phosphorylated. These observations suggest that ionic strength and dephosphorylation may provide switching mechanisms to trigger a change in the function of the N-terminus during enamel development. [ABSTRACT FROM AUTHOR]

2H and 15N solid-state NMR spectroscopic techniques were used to investigate both the side chain and backbone dynamics of wild-type phospholamban (WT-PLB) and its phosphorylated form (P- PLB) incorporated into I -palmitoyl-2-oleoyl-sn-glycerophosphocholine (POPC) phosphol ipid bilayers. 2H NMR spectra of site-specific CD3-labeled WT-PLB (at Leu51, Ala24, and Ala 15) in POPC bilayers were similar under frozen conditions (-25 °C). However, significant differences in the line shapes of the 2H NMR spectra were observed in the liquid crystalline phase at and above 0 °C. The 2H NMR spectra indicate that Leu51, located toward the lower end of the transmembrane (TM) helix, shows restricted side chain motion, implying that it is embedded inside the POPC lipid bilayer. Additionally, the line shape of the 2H NMR spectrum of CD3-Ala24 reveals more side chain dynamics, indicating that this residue (located in the upper end of the TM helix) has additional backbone and internal side chain motions. 2H NMR spectra of both WT-PLB and P-PLB with CD3-Ala15 exhibit strong isotropic spectral line shapes. The dynamic isotropic nature of the 2H peak can be attributed to side chain and backbone motions to residues located in an aqueous environment outside the membrane. Also, the spectra of 15N-labeled amide WT- PLB at Leu51 and Leu42 residues showed only a single powder pattern component indicating that these two 15N-labeled residues located in the TM helix are motionally restricted at 25 °C. Conversely, 15N- labeled amide WT-PLB at Ala11 located in the cytoplasmic domain showed both powder and isotropic components at 25 °C. Upon phosphorylation, the mobile component contribution increases at Ala11. The 2H and 15N NMR data indicate significant backbone motion for the cytoplasmic domain of WT-PLB when compared to the transmembrane section. [ABSTRACT FROM AUTHOR]

Two novel ethynylcrown ether containing di- and tetranuclear gold(i) complexes have been synthesized and structurally characterized; their binding ability toward various metal ions has also been studied. [ABSTRACT FROM AUTHOR]

Herein, we introduce an electrochemical dehydrogenative [3 + 2]/[5 + 2] annulation of easily available N -arylacrylamides with γ,σ-unsaturated malonates through C(sp 3 )-H/C(sp 2 )-H functionalization. The employment of inexpensive ferrocene as the redox catalyst allows access to diverse benzo[ b ]azepin-2-ones in moderate to excellent yields without stoichiometric oxidants. This protocol features broad substrate scope and excellent selectivity, and mechanistic studies indicated that the reaction proceeded through the oxidation of a C(sp 3 )-H bond to generate an alkyl radical, radical addition across the C═C bond, [3 + 2]/[5 + 2] annulations, and C(sp 2 )-H functionalization cascades.

The wettable surface or nonwettable surface that is derived from a multilevel micronanoscale structure is abundant in nature and biomimetic commodities. Those hoverflies with the seta-coated wing membrane detached from impacting free-falling raindrops were observed in static states. A hoverfly wing membrane with well-ordered setae was identified as a robust nonwettable surface, and the static water contact angle θ on the wing membrane at the microscopic scale is 136.84 ± 0.98°. Hoverfly wing membrane-water droplet interaction with the actual truth and the theoretical models was discussed and indicated that the theoretical calculation might not state the actual situation, arising from the membrane or seta-drop-bubble interaction and those multilevel micronanoscale structure characteristics on the wing membrane. Detailed investigation on nonwettable surface-wettable surface transformation with surface CaCO 3 accumulation in a carbonization reaction and the characteristic transformation toward the hoverfly wing membrane with the multilevel micronanoscale structure was carried out. Then, the CaCO 3 accumulation on PDMS texture films was carried out and the static water contact angle θ was tested. Those observations offer ideas to fabricate artificial films with a multilevel micronanoscale structure that could obtain some characteristics, i.e., nonwettable surface-wettable surface transformation.

Nickel (poly)sulfides have been widely studied as anodic catalysts for alkaline water electrolysis owing to their diverse morphologies, high catalytic activities in the oxygen evolution reaction (OER), and low cost. To utilize low-cost and high-efficiency polysulfides with industry-relevant cycling stability, we develop a Ni-rich NiS x /Ni(OH) 2 /NiOOH catalyst derived from NiS 2 /Ni 3 S 4 nanocubes. Ni-rich NiS x /Ni(OH) 2 /NiOOH shows improved OER catalytic activity (η = 374 mV@50 mA cm -2 ) and stability (0.1% voltage increase) after 65 h of a galvanostatic test at 10 mA cm -2 compared with commercial Ni/NiO and hydrothermally synthesized Ni(OH) 2 (both show η > 460 mV@50 mA cm -2 along with 4.40 and 1.92% voltage increase, respectively). A water-splitting electrolyzer based on Pt/C||AF1-HNN8-50||NiS x /Ni(OH) 2 /NiOOH exhibits a current density of 1800 mA cm -2 at 2.0 V and 500 h high-rate stability at 1000 mA cm -2 with negligible attenuation of only 0.12 mV h -1 . This work provides an understanding of truly stable species, intrinsic active phases of Ni polysulfides, their high-rate stability in a real cell, and sheds light on the development of stable chalcogenide-based anodic electrocatalysts for anion exchange membrane water electrolysis (AEMWE).

Perovskites show excellent specific catalytic activity toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline solutions; however, small surface areas of the perovskites synthesized by traditional sol-gel methods lead to low utilization of catalytic sites, which gives rise to poor Li-O2 batteries performance and restricts their application. Herein, a hierarchical mesporous/macroporous perovskite La0.5Sr0.5CoO3-x (HPN-LSC) nanotube is developed to promote its application in Li-O2 batteries. The HPN-LSC nanotubes were synthesized via electrospinning technique followed by postannealing. The as-prepared HPN-LSC catalyst exhibits outstanding intrinsic ORR and OER catalytic activity. The HPN-LSC/KB electrode displays excellent performance toward both discharge and charge processes for Li-O2 batteries, which enhances the reversibility, the round-trip efficiency, and the capacity of resultant batteries. The synergy of high catalytic activity and hierarchical mesoporous/macroporous nanotubular structure results in the Li-O2 batteries with good rate capability and excellent cycle stability of sustaining 50 cycles at a current density of 0.1 mA cm(-2) with an upper-limit capacity of 500 mAh g(-1). The results will benefit for the future development of high-performance Li-O2 batteries using hierarchical mesoporous/macroporous nanostructured perovskite-type catalysts.