Structural Analyses of Designed α-Helix and β-Sheet Peptide Nanofibers Using Solid-State Nuclear Magnetic Resonance and Cryo-Electron Microscopy and Introduction of Structure-Based Metal-Responsive Properties.

The 21-residue peptide α3, which is artificially designed and consists of three repeats of 7 residues, is known to rapidly assemble into the α-helix nanofiber. However, its molecular structure within the fiber has not yet been fully elucidated. Thus, we conducted a thorough investigation of the fiber's molecular structure using solid-state NMR and other techniques.

The Atomic Observation of the Structural Change Process in Pt Networks in Air Using Environmental Cell Scanning Transmission Electron Microscopy.

The structural change in Pt networks composed of multiple chain connections among grains was observed in air at 1 atm using atomic-resolution environmental cell scanning transmission electron microscopy. An aberration-corrected incident electron probe with a wide convergence angle made it possible to increase the depth resolution that contributes to enhancing the signal-to-noise ratio of Pt network samples in air in an environmental cell, resulting in the achievement of atomic-resolution imaging. The exposure of the Pt networks to gas molecules under Brownian motion, stimulated by electron beams in the air, increases the collision probability between gas molecules and Pt networks, and the Pt networks are more intensely stressed from all directions than in a situation without electron irradiation.

Gelation of a π-Decorated Glutamate as a Homochiral Selective Self-assembly to Obtain Macroscopic Chiral Symmetry Breaking.

An N-Fmoc and C-tBu-protected glutamate (1) bearing a phenanthrene moiety at the side residue crystalizes and gels to afford hetero- and homochiral assemblies, respectively, depending on its optical purity or solvent. When a non-stoichiometric mixture of enantiomers of 1 in acetonitrile was treated with the conditions that leave a mixture of gel and supernatant, it exhibited the self-disproportionation of enantiomers with an enrichment of the major enantiomer in the gel. Under similar conditions, a racemic mixture of 1 also provided a gel/supernatant mixture, where the gel was enriched in either of L or D-form of 1 stochastically as the result of macroscopic chiral symmetry breaking in its gelation process.

Malate-aided selective crystallization and luminescence comparison of tetragonal and monoclinic LaVO:Eu nanocrystals.

With malate (Mal2-) as a new type of chelate, tetragonal (t-) and monoclinic (m-) structured LaVO4:Eu crystals (∼10-60 nm) were selectively crystallized as nanosquares and nanorods via a hydrothermal reaction at 200 °C for 24 h. The effects of the Mal2-:(La,Eu)3+ molar ratio, solution pH and Eu3+ content on the phase structure and crystal morphology were systematically investigated and elucidated. The competition between OH- and Mal2- toward rare earth ions was discussed to play a critical role in phase selection, and the t-phase can only be fabricated at pH ∼ 6-8 with the assistance of Mal2-.

L-Citrulline ameliorates the attenuation of acetylcholine-induced vasodilation of retinal arterioles in diabetic rats.

In our previous study, we found that the vasodilation of retinal arterioles induced by acetylcholine and BMS-191011, a large-conductance Ca-activated K (BK) channel opener, were diminished in diabetic rats. Currently, few agents ameliorate the impaired vasodilator responses of retinal blood vessels. Our recent finding that the intravenous infusion of L-citrulline dilated retinal arterioles, suggests that L-citrulline could be a potential therapeutic agent for circulatory disorders of the retina.

Interleukin-6 sensitizes TNF-α and TRAIL/Apo2L dependent cell death through upregulation of death receptors in human cancer cells.

Interleukin-6 (IL-6) enhanced TNF-α and TRAIL/Apo2L induced cell death in various human cancer cells derived from malignant glioma, melanoma, breast cancer and leukemia, although the effect was not detected with IL-6 alone. The effects of IL-6 using SKBR3 cells were associated with the generation of apoptotic cells as analyzed by fluorescence microscopy and flow cytometry. IL-6 activated p53 and upregulated TRAIL death receptors (DR-4 and DR-5) and stimulated the TNF-α and TRAIL dependent extrinsic apoptotic pathway without activation of the p53 mediated intrinsic apoptotic pathway.

Coalescence-Driven Verticality in Mesoporous TiO Thin Films with Long-Range Ordering.

Mesoporous semiconducting films with continuous interconnectivity and minimal tortuosity, such as densely ordered arrays of vertical channels, are ideal for ensuring a maximal surface area at the heterojunction to increase the density of charges or photons. While the design of these films with nanostructures below 50 nm using modern lithography is not feasible, continuously perpendicular pores can be obtained throughout a TiO film using a traditional soft-templating approach and lyotropic crystal engineering. We demonstrate here that a polystyrene--poly(ethylene oxide) block copolymer in a three-solvent system can self-assemble into a body-centered cubic template.

Tailored Design of Mesoporous PdCu Nanospheres with Different Compositions Using Polymeric Micelles.

Mesoporous metals have attracted a lot of interest due to their wide range of applications, particularly in catalysis. We previously reported the preparation of mesoporous Pd using block copolymer micelle templates ( , , 4054). Here we extend this synthetic concept to generate alloyed spherical palladium-copper (PdCu) nanoparticles with an open porous network and uniform morphology.

ITO@SiO and ITO@{MBr}@SiO (M = Nb, Ta) nanocomposite films for ultraviolet-near infrared shielding.

Transparent optical thin films for energy saving applications have recently gained substantial prominence for functional window processes. In this study, highly visible transparent nanocomposite films with ultraviolet (UV) and near-infrared (NIR) blocking capabilities are reported. Such nanocomposite films, prepared by electrophoretic deposition on ITO-coated glass, are composed of indium tin oxide (ITO) nanocrystals (9 nm) and octahedral metal atom clusters (1 nm, Nb or Ta) embedded into silica nanoparticles (∼80 nm).

Condensed ferric dimers for green photocatalytic synthesis of nylon precursors.

Although iron oxides have been extensively studied as photocatalysts because of their abundance and environmental compatibility, their performance is notoriously low due to factors such as low photoinduced charge-separation efficiency. Iron oxides, thus, must be modified with expensive and/or toxic materials to attain higher performances, which devalues their appeal as sustainable materials. Here, we design an iron oxide exhibiting an unprecedentedly high photocatalytic performance unrealized by previous photocatalysts such as TiO for reactions including the selective oxidation of cyclohexane to industrial nylon precursors.

Morphology Tailoring of ZnWO Crystallites/Architectures and Photoluminescence of the Doped RE Ions (RE = Sm, Eu, Tb, and Dy).

Tartrate (Tar) was originally employed in this work as a chelating/structure-directing agent for hydrothermal crystallization of ZnWO, where the decisive roles of Tar/Zn/WO molar ratio, solution pH (7-10), and the use of ethylene glycol (EG) cosolvent in phase/morphology evolution were deciphered in detail. It was unambiguously manifested that Tar may remarkably retard the intrinsically preferred [001] growth of ZnWO, transform 1D nanorods to 0D nanoparticles and then to 2D platelets, and meanwhile induce face-to-face alignment of the platelets to form spheroidal, ellipsoidal and snowflakelike 3D architectures, where the 2D crystallites were revealed to develop via oriented attachment (colattice) of non-(00) facets. A lower solution pH and excessive WO were clearly shown to enhance and offset the effect of Tar, which led to ellipsoidal assemblies of substantially larger 2D crystallites and suppressed 2D growth/3D assembly of ZnWO crystallites, respectively.

The Ouzo effect to selectively assemble molybdenum clusters into nanomarbles or nanocapsules with increased HER activity.

Metal cluster nanoparticles are obtained by simple solvent shifting called the Ouzo effect. Remarkably, the assembly of [{Mo6Br8}L6]2- (L = Br- or NCS-) cluster units can be directed into nanomarbles or nanocapsules depending on the cluster chemistry. When deposited on electrodes, these nanoparticles show good activities in electrochemical water splitting under mild conditions.

Hole gas accumulation in Si/Ge core-shell and Si/Ge/Si core-double shell nanowires.

Core-shell nanowires (NWs) composed of silicon and germanium can be used to realize high electron (hole) mobility transistors (HEMTs) by suppressing impurity scattering due to their band offset structure and selective doping. Boron doped p-type Si/intrinsic-Ge (i-Ge) core-shell NW structures are selected to study this phenomenon. To produce HEMT devices, hole gas accumulation must be controlled in the impurity undoped i-Ge shell layers.

Sub-50 nm Iron-Nitrogen-Doped Hollow Carbon Sphere-Encapsulated Iron Carbide Nanoparticles as Efficient Oxygen Reduction Catalysts.

Sub-50 nm iron-nitrogen-doped hollow carbon sphere-encapsulated iron carbide nanoparticles (FeC-Fe,N/C) are synthesized by using a triblock copolymer of poly(styrene--2-vinylpyridine--ethylene oxide) as a soft template. Their typical features, including a large surface area (879.5 m g), small hollow size (≈16 nm), and nitrogen-doped mesoporous carbon shell, and encapsulated FeC nanoparticles generate a highly active oxygen reduction reaction (ORR) performance.

Embedding hexanuclear tantalum bromide cluster {TaBr} into SiO nanoparticles by reverse microemulsion method.

Hexanuclear tantalum bromide cluster units [{TaBr}L] (i = inner, a = apical, L = ligand OH or HO) are embedded into SiO nanoparticles by a reverse microemulsion (RM) based method. [{TaBr}Br (HO)]·HO (noted TBH) and tetraethyl orthosilicate (TEOS) are used as the starting cluster compound and the precursor of SiO, respectively. The RM system in this study consists of the -heptane (oil phase), Brij L4 (surfactants), ethanol, TEOS, ammonia solution and TBH aqueous sol.

Stable Blue Luminescent CsPbBr Perovskite Nanocrystals Confined in Mesoporous Thin Films.

Creating CsPbBr perovskite nanocrystals with bright blue emission is challenging because their optical properties depend sensitively on structure. Growing perovskites in mesoporous templates bypasses some of these purification issues because the size of the nanocrystal is governed by the dimensions of the pores. Mesoporous silica consisting of aligned channels with tunable diameter can be easily synthesized and used as a template.

Investigation of nanoscale voids in Sb-doped p-type ZnO nanowires.

While it has multiple advantageous optoelectronic and piezoelectric properties, the application of zinc oxide has been limited by the lack of a stable p-type dopant. Recently, it was discovered that antimony doping can lead to stable p-type doping in ZnO, but one curious side effect of the doping process is the formation of voids inside the nanowire. While previously used as a signifier of successful doping, up until now, little research has been performed on these structures themselves.

A Glutathione-Responsive Short Sequence of Metal-Organic Complex Array.

A short metal-organic complex array (MOCA) containing a sequence of RPtRRu (1 ) was found to exhibit unique responses to a major biothiol, glutathione (GSH). Upon binding of GSH to 1 , the resultant 1:1 complex (1 ) formed nanofibrous assemblies that suggested supramolecular polymerization through the double-salt-bridge structure formation. The binding behavior of this MOCA sequence to calf thymus DNA was also dependent on GSH; a larger conformational change of DNA was observed upon binding with 1 , relative to that with 1 .

Selective Crystallization of Four Tungstates (LaWO, LaWO, LaWO, and LaWO) via Hydrothermal Reaction and Comparative Study of Eu Luminescence.

Hydrothermal reaction at 200 °C was systematically undertaken in wide ranges of solution pH (4-13) and W/La molar ratio ( R = 0.5-2), without using any organic additive, to investigate the effect of hydrothermal parameter on product property and the underlying mechanism. Combined analysis by X-ray diffraction (XRD), inductively coupled plasma (ICP) spectroscopy, elemental mapping, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that either a decreasing pH or increasing R value yielded a product richer in W and, conversely, richer in La.

Merging Cation Exchange and Photocatalytic Charge Separation Efficiency in an Anatase/KTiO Nanobelt Heterostructure for Metal Ions Fixation.

Efficient collection and safe disposal of toxic metals ions from aqueous solutions is critical for applications in environmental remediation. Although extensive efforts have been devoted to the synthesis of functional TiO materials, photocatalytic reduction (photoreduction) of aqueous metal ions into solid metals remains a challenge. We designed a TiO nanoparticle-decorated layered titanate (KTiO) material that retained the cation exchange ability of KTiO but also possessed the enhanced charge separation efficiency of KTiO.

Spatially Confined Assembly of Monodisperse Ruthenium Nanoclusters in a Hierarchically Ordered Carbon Electrode for Efficient Hydrogen Evolution.

The redox units of polyaniline (PAni) are used cooperatively, and in situ, to assemble ruthenium (Ru) nanoclusters in a hierarchically ordered carbon electrode. The oxidized quinonoid imine (QI) units in PAni bond Ru complex ions selectively, whereas reduced benzenoid amine (BA) units cannot. By electrochemically tuning the ratio of QI to BA, Ru complexes are spatially confined in the outer layer of hierarchical PAni frameworks.

Templated synthesis of atomically-thin Ag nanocrystal catalysts in the interstitial space of a layered silicate.

Enclosing functional nanoparticles in stable inorganic supports is important for generating ultra-stable catalytic active sites with good performance and material utilization efficiency. Here we describe a simple method to synthesize ultra-thin Ag nanocrystals with dimensions that are defined by the ∼1.4 nm 2D interlayer separating a layered silicate nanostructure.

Self-Template-Directed Metal-Organic Frameworks Network and the Derived Honeycomb-Like Carbon Flakes via Confinement Pyrolysis.

Metal-organic frameworks (MOFs) have become a research hotspot since they have been explored as convenient precursors for preparing various multifunctional nanomaterials. However, the preparation of MOF networks with controllable flake morphology in large scale is not realized yet. Herein, a self-template strategy is developed to prepare MOF networks.

Enhanced Solar Light Absorption and Photoelectrochemical Conversion Using TiN Nanoparticle-Incorporated CN-C Dot Sheets.

In this work, a promising strategy to increase the broadband solar light absorption was developed by synthesizing a composite of metal-free carbon nitride-carbon dots (CN-C dots) and plasmonic titanium nitride (TiN) nanoparticles (NPs) to improve the photoelectrochemical water-splitting performance under simulated solar radiation. Hot-electron injection from plasmonic TiN NPs to CN played a role in photocatalysis, whereas C dots acted as catalysts for the decomposition of HO to O. The use of C dots also eliminated the need for a sacrificial reagent and prevented catalytic poisoning.