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Solution-processed quasi-2D perovskites contain multiple quantum wells with a broad width distribution. Inhomogeneity results in the charge funneling into the smallest bandgap components, which hinders deep-blue emission and accelerates Auger recombination. Here, a synthetic strategy applied to a range of quasi-2D perovskite systems is reported, that significantly narrows the quantum well dispersity. It is shown that the phase distribution in the perovskite film is significantly narrowed with controlled, simultaneous evaporation of solvent and antisolvent. Modulation of film formation kinetics of quasi-2D perovskite enables stable deep-blue electroluminescence with a peak emission wavelength of 466 nm and a narrow linewidth of 14 nm. Light emitting diodes using the perovskite film show a maximum luminance of 280 cd m

Ex-solution catalysts, in which a host oxide is decorated with confined metallic nanoparticles, have exhibited breakthrough activity in various catalytic reactions. However, catalysts prepared by conventional ex-solution processes are limited by the low surface area of host oxides, the limited solubility of dopants, and the incomplete conversion of doped cations into metal catalysts. Here, the design of the host oxide structure is reconceptualized using a metal-organic framework (MOF) as an oxide precursor that can absorb a large quantity of ions while also promoting ex-solution at low temperatures (400-500 °C). The MOF-derived metal oxide host can readily incorporate metal cations, from which catalytic nanoparticles can be uniformly ex-solved owing to the short diffusion length in the nano-sized oxides. The distinct ex-solution behaviors of Pt, Pd, and Rh, and their bimetallic combinations are investigated. The MOF-driven mesoporous ZnO particles functionalized with PdPt catalysts ex-solved at 500 °C show benchmark-level of acetone oxidation activity as well as acetone-sensing characteristics by accelerating both oxygen chemisorption and acetone dissociation. Their findings provide a new route for the preparation of highly active catalysts by engineering the architecture and composition of the host oxide to facilitate the ex-solution process rationally.

Central nervous system (CNS) metastasis is one of the serious complications of epidermal growth factor receptor (EGFR)‐mutant lung cancer, which arises due to poor penetration of the brain–blood barrier by EGFR‐tyrosine kinase inhibitors (EGFR‐TKIs). Although osimertinib, a third‐generation EGFR‐TKI, has efficacy against CNS metastases, further treatment modalities are still needed as some of these lesions do not respond to osimertinib, or undergo progression after an initial response to this drug if radiotherapy has already been conducted. Here, we investigated the efficacy of water‐soluble erlotinib (NUFS‐sErt) against these metastases. This agent was synthesized using a nano‐particulation platform technology utilizing fat and supercritical fluid (NUFS™) to resolve the low solubility problem that typically prevents the creation of injectable forms of EGFR‐TKIs. The average NUFS‐sErt particle size was 236.4 nm, and it showed time‐dependent dissolution in culture media. The effects of NUFS‐sErt were similar to those of conventional erlotinib in terms of inhibiting the proliferation of EGFR‐mutant lung cancer cells and suppressing EGFR signaling. In an intraperitoneal xenograft model of HCC827 cells, intraperitoneal administration of NUFS‐sErt produced a dose‐dependent inhibition of tumor growth and enhanced survival rate. Notably, the injection of NUFS‐sErt into the brain ventricle caused significant tumor growth inhibition in an intracranial xenograft model. Hence, our current findings indicate that NUFS‐sErt is a novel, water‐soluble form of erlotinib that can be administered using intraventricular or intrathecal injections. The target cases would be patients with a progressive CNS metastasis and no other therapeutic options. This drug could also be given intravenously to patients with swallowing difficulties or an inability to ingest due to a medical condition.

A two-step ligand-exchange strategy is developed, in which the long-carbon- chain ligands on all-inorganic perovskite (CsPbX3 , X = Br, Cl) quantum dots (QDs) are replaced with halide-ion-pair ligands. Green and blue light-emitting diodes made from the halide-ion-pair-capped quantum dots exhibit high external quantum efficiencies compared with the untreated QDs.

Resistive random access memory (ReRAM) devices powered by piezoelectric nanogenerators (NGs) have been investigated for their application to future implantable biomedical devices. Biocompatible (Na0.5K0.5)NbO3 (NKN) films that are grown at 300 °C on TiN/SiO2/Si and flexible TiN/Polyimide (TiN-PI) substrates are used for ReRAM and NGs, respectively. These NKN films have an amorphous phase containing NKN nanocrystals with a size of 5.0 nm. NKN ReRAM devices exhibit typical bipolar switching behavior that can be explained by the formation and rupture of oxygen-vacancy filaments. They have good ReRAM properties such as a large ratio of RHRS to RLRS as well as high reliability. The NKN film grown on flexible TiN-PI substrate exhibits a high piezoelectric strain constant of 50 pm V−1. The NKN NG has a large open-circuit output voltage of 2.0 V and a short-circuit output current of 40 nA, which are sufficient to drive NKN ReRAM devices. Stable switching properties with a large ON/OFF ratio of 102 are obtained from NKN ReRAM driven by NKN NG.

The ex-solution phenomenon, a central platform for growing metal nanoparticles on the surface of host oxides in real time with high durability and a fine distribution, has recently been applied to various scientific and industrial fields, such as catalysis, sensing, and renewable energy. However, the high-temperature processing required for ex-solutions (>700 °C) limits the applicable material compositions and has hindered advances in this technique. Here, an unprecedented approach is reported for low-temperature particle ex-solution on important nanoscale binary oxides. WO3 with a nanosheet structure is selected as the parent oxide, and Ir serves as the active metal species that produces the ex-solved metallic particles. Importantly, Ir doping facilitates a phase transition in the WO3 bulk lattice, which further promotes Ir ex-solution at the oxide surface and eventually enables the formation of Ir particles (

Hybrid plasmonic nanostructures comprising gold nanoparticle (AuNP) arrays separated from Au substrate through a temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM) linker layer are constructed, and unique plasmonic-coupling-based surface plasmon resonance (SPR) sensing properties are investigated. The optical properties of the model system are investigated by in situ and scan-mode SPR analysis. The swelling-shrinking transitions in the polymer linker brush are studied by in situ contact-mode atomic force microscopy at two different temperatures in water. It is revealed that the thickness of the PNIPAM layer is decreased from 30 to 14 nm by increasing the temperature from 20 to 32 °C. For the first time the dependence of the coupling behavior in AuNPs is investigated with controlled density on the temperature in a quantitative manner in terms of the change in SPR signals. The device containing AuNPs with optimized AuNP density shows 3.2-times enhanced sensitivity compared with the control Au film-PNIPAM sample. The refractive index sensing performance of the Au film-PNIPAM-AuNPs is greater than that of Au film-PNIPAM by 19% when the PNIPAM chains have a collapsed conformation above lower critical solution temperature.

Early diagnosis and effective cancer therapy are required, to properly treat cancer, which causes more than 8.2 million deaths in a year worldwide. Among various cancer treatments, nanoparticle-based cancer therapies and molecular imaging techniques have been widely exploited over the past decades to overcome current drawbacks of existing cancer treatments. In particular, gold nanoparticles (AuNPs), carbon nanotubes (CNTs), graphene oxide (GO), and upconversion nanocrystals (UNCs) have attracted tremendous attention from researchers due to their near-infrared (NIR) light-responsive behaviors. These nanomaterials are considered new multifunctional platforms for cancer theranostics. They would enable on-demand control of drug release or molecular imaging in response to a remote trigger by NIR light exposure. This approach allows the patient or physician to adjust therapy precisely to a target site, thus greatly improving the efficacy of cancer treatments, while reducing undesirable side effects. In this review, we have summarized the advantages of NIR light-responsive nanomaterials for in vivo cancer treatments, which includes NIR triggered photothermal therapy (PTT) and photodynamic therapy (PDT). Furthermore, recent developments, perspectives, and new challenges of NIR light-responsive nanomaterials are discussed for cancer theranostic applications.

Mesoporous TiO2 and carbon-TiO2 beads with highly roughened surfaces at the nanoscale were prepared by using triblock copolymer P123 simultaneously as template and carbon source in combination with colloid self-assembly. In addition, their role as modifier of the photoanode in the efficiency enhancement of dye-sensitized solar cells is discussed. Hierarchically organized TiO2 networks can provide fast electron transport paths, and ordered mesopores can enhance light scattering as well as facilitate infiltration of the electrolyte. It was found that there is an optimum loading level of mesoporous TiO2 and carbon-TiO2 beads, that is, 1.0 and 0.5 wt %, with respect to the control P25 TiO2 nanoparticles, respectively, for maximizing the photovoltaic performance. An increase in the photovoltaic performance by up to 21.45 % was achieved by incorporation of mesoporous carbon-TiO2 beads into the conventional photoanode of DSSCs owing to enhanced charge transport and collection effects.

A method to fabricate micropatterns of non-circular droplets of a self-assembled block copoly mer by solvent-assisted wetting on chemically periodic surface is presented. The block copolymer is dewetted on a topographic pre-pattern to form an array of microdroplets with a sphere-capped shape and circular contact line. The droplets are then transferred onto a chemically periodic Au line pattern microcontact-printed with two types of self-assembled monolayers (SAMs). Solvent vapor application provides suffi cient mobility to the block copolymer molecules to induce spreading of the transferred droplets, resulting in two types of non-circular microdroplet growth. The growth behavior depends on the size of initial droplets relative to periodic line width and on the initial registries of as-transferred droplets.

A quick protocol for the fabrication of ultrahigh density arrays of toroidal ZnO nanostructures with tailored structures on a substrate surface is presented based on the one-step spin coating of a common solution composed of inverse micelles of polystyrene-block-poly(4-vinyl pyridine) copolymers (PS-b-P4VP) and sol-gel precursors without the need of conventional complex lithographic techniques. ZnO toroids decorated with gold nanoparticles are also obtained by subsequent loading and reduction of metallic precursors. It was elucidated that the diethanolamine moiety in the sol-gel precursors, which induces selective swelling and structural reorganization of the P4VP core blocks, plays a key role in the generation of toroidal nanostructures. Toroidal ZnO nanostructures embedded in a PS-b-P4VP matrix films or arrays of pure wurtzite ZnO nanorings are obtained by calcination under inert atmosphere. The structural parameters of the toroidal nanostructures such as the width, height, diameter of the rims as well as the spacing of their 2D arrays are controlled by employing PS-b-P4VP with different molecular weight and varying the mixing protocols.

A simple scheme to fabricate 2-D arrays of Au/titania hybrid nanopatterns is presented, using polystyrene-block-poly(ethylene oxide) diblock copolymer (PS-b-PEO) as templates coupled with sol-gel chemistry. Both the functionalized Au nanoparticles (NPs) and titania precursors are selectively incorporated into the PEO domain. A series of morphologies ranging from nanodot to nanowire arrays is formed and the mechanism of morphological evolution is discussed. Such hybrid films exhibit characteristic localized surface plasmon resonance bands originating from the coupling between neighboring Au NPs spatially located in a controlled manner.

This paper proposes to utilize a stock market instability index (SMII) to develop an early warning system for financial crisis. The system focuses on measuring the differences between the current market conditions and the conditions of the past when the market was stable. Technically the system evaluates the current time series against the past stable time series modelled by an asymptotic stationary autoregressive model via artificial neural networks. Advantageously accessible to extensive resources, the system turns out better results than the conventional system which detects similarities between the conditions of the current market and the conditions of previous markets that were in crisis. Therefore, it should be considered as a more advanced tool to prevent financial crises than the conventional one. As an empirical example, an SMII for the Korean stock market is developed in order to demonstrate its potential usefulness as an early warning system.

There is considerable interest in developing functional protein arrays on the nanoscale for high-throughput protein-based array technology, and for the study of biomolecular and cell interactions at the physical scale of the biomolecules. To these ends, self-assembly based techniques may be desirable for the nanopatterning of proteins on large sample areas without the use of lithography equipment. We present a fast, general approach for patterning proteins (and potentially other biomolecules) on the nanoscale, which takes advantage of the ability of block copolymers to self-assemble into ordered surface nanopatterns with defined chemical heterogeneity. We demonstrate nanoarrays of immunoglobulin and bovine serum albumin on polystyrene-block-poly(methyl methacrylate) templates, and illustrate the applicability of our technique through immunoassays and DNA sensing performed on the protein nanoarrays. Furthermore, we show that the pattern formation mechanism is a nanoscale effect originating from a combination of fluid flow forces and geometric restrictions templated by an underlying nanopattern with a difference in protein adsorption behavior on adjacent, chemically distinct surfaces. This understanding may provide a framework for extending the patterning approach to other proteins and material systems.

We report a simple scheme to fabricate organic/inorganic hybrid nanostructures with extraordinary morphologies by one-step spin coating, using a PS-b-PEO diblock copolymer astemplate coupled with sol-gelchemistry. The shapeand size ofthe titaniananoobjectcan be fine-tuned by controlling the amount of sol-gel precursor relative to PS-b-PEO and the composition of the precursor. Ordered arrays of nanoscopic titania objects such as nanodots, nanobowls, and nanonetworks were obtained from the initial hybrid nanostructures by removing the organic matrix by UV treatment. Photocatalytic activities of the resulting titania nanoobjects were investigated in terms of the degradation of a typical dye.

We have systematically studied the thin film morphologies of asymmetric polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer subjected to solvent vapors of varying selectivity for the constituent blocks. Upon a short treatment in neutral or PS-selective vapor, the film exhibited a highly ordered array of hexagonally packed, cylindrical microdomains. In the case of PEO selective vapor annealing, such ordered cylindrical microdomains were not obtained. instead, fractal patterns on the microscale were observed and their growth processes investigated. Furthermore, hierarchical structures could be obtained if the fractal pattern was exposed to neutral or PS selective vapor.

Thin films of diblock copolymers with cylindrical microdomains oriented normal to the film plane are employed as planar optical waveguides in the Kretschmann configuration (see Figure). Their waveguiding properties were investigated by optical waveguide spectroscopy. The dielectric constants and the film thickness of the block copolymer layer can be independently obtained from fitting between the waveguide patterns for s- and p-polarization and Fresnel calculations.

Nanodomains formed by microphase separation in thin films of the diblock copolymers poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) and poly(styrene-b-ethyleneoxide) (PS-b-PEO) were imaged by means of infrared scattering-type near-field microscopy. When probing at 3.39 mum (2950 cm(-1)), contrast is obtained due to spectral differences between the C--H stretching vibrational resonances of the respective polymer constituents. An all-optical spatial resolution better than 10 nm was achieved, which corresponds to a sensitivity of just several thousand C--H groups facilitated by the local-field enhancement at the sharp metallic probe tips. The results demonstrate that infrared spectroscopy with access to intramolecular dimensions is within reach.

A simple route to an ordered array of metal/ semiconductor oxide composite nanodots is presented. Micellar monolayer films of polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) loaded with HAuCl 4 in the P2VP nanodomains are used as templates. TiO 2 is generated selectively within the polar P2VP domains of PS-b-P2VP/HAuCl 4 films by chemical vapor deposition of TiCl 4 . Subsequent removal of the organic matrix by oxygen plasma or UV light leads to an array of Au/TiO 2 composite nanoparticles on the substrate surface.

A simple route for fabricating highly ordered organic-inorganic hybrid nanostructures, using polystyrene-block-poly(ethylene oxide) diblock copolymer (PS-b-PEO) thin films coupled with sol-gel chemistry, is presented. Hexagonally packed arrays of titania nanodomains were generated by one-step spin-coating from solutions containing a titania precursor and PS-b-PEO, where the precursor was selectively incorporated into the PEO domain. The PS-b-PEO template was subsequently removed by UV treatment, leaving behind a highly dense array of hexagonally packed titania dots. The size of the dots, as well as the lattice spacing of the array, could be fine-tuned by simply controlling the relative amount of sol-gel precursor to PS-b-PEO.

Assemblies of oppositely charged L-lysine/carboxylic acid functionalized polyphenylene dendrimers and hybrid multilayers of L-lysine dendfinwrs/colloidal gold nanocrystals were fabricated as alternate multilayers on 3-mercaptopropionic acid coated gold surfaces via layer-bylayer deposition. The fabrication of the multilayer films was monitored by kinetic and scan mode surface plasmon resonance spectroscopy. The permeability properties of the dendritic polyelectrolyte layers were characterized by electrochemistry in the presence of [Fe(CN) 6 ] 3-/4- as the redox couple. A high interfacial charge-transfer resistance, originating from the electrostatic repulsion of the negatively charged redox couple against the negatively charged interface was observed and the charge-transfer resistance found to increase with increasing number of layers.