Membraneless Ionic Liquid Droplet Nanoprobe for Oxygen Sensing and Gas Phase Scanning Electrochemical Microscopy.

A novel membraneless oxygen sensing nanoprobe was developed based on a hanging drop ionic liquid electrochemical cell. An ultrasmall (<500 nm) working electrode and small volume electrochemical cell allowed for an impressively low detection limit of ∼13 ppm and a response time less than 100 ms, which is unusually fast for an electrochemical gas sensor. The oxygen sensor was stable for hours of operation and, owing to the membraneless design, was easily regenerable when fouled.

Carbon-free high-performance cathode for solid-state Li-O battery.

The development of a cathode for solid-state lithium-oxygen batteries has been hindered in practice by a low capacity and limited cycle life despite their potential for high energy density. Here, a previously unexplored strategy is proposed wherein the cathode delivers a specific capacity of 200 milliampere hour per gram over 665 discharge/charge cycles, while existing cathodes achieve only ~50 milliampere hour per gram and ~100 cycles. A highly conductive ruthenium-based composite is designed as a carbon-free cathode by first-principles calculations to avoid the degradation associated with carbonaceous materials, implying an improvement in stability during the electrochemical cycling.

Curvature-Induced Twist in Homeotropic Nematic Tori.

We confine a nematic liquid crystal with homeotropic anchoring to stable toroidal droplets and study how geometry affects the equilibrium director configuration. In contrast to the case of cylindrical confinement, we find that the equilibrium state is chiral-a twisted and escaped radial director configuration. Furthermore, we find that the magnitude of the twist distortion increases as the ratio of the ring radius to the tube radius decreases; we confirm this with computer simulations of optically polarized microscopy textures.

Ion-channel aligned gas-blocking membrane for lithium-air batteries.

Lithium-metal-based batteries, owing to the extremely high specific energy, have been attracting intense interests as post-Li-ion batteries. However, their main drawback is that consumption/de-activation of lithium metal can be accelerated when O or S used in the cathode crosses over to the metal, reducing the lifetime of the batteries. In use of ceramic solid state electrolyte (SSE) separator, despite the capability of gas blocking, thick and heavy plates (~0.

Polypeptide Composite Particle-Assisted Organization of π-Conjugated Polymers into Highly Crystalline "Coffee Stains".

We demonstrate that homopolypeptides covalently tethered to anisotropically shaped silica particles induce crystalline ordering of representative semiconducting polymers. Films drop-cast from chloroform dispersions of poly(γ-stearyl-l-glutamate) (PSLG) composite particles and poly(3-hexythiophene) (P3HT) led to highly ordered crystalline structures of P3HT. Hydrophobic-hydrophobic interactions between the alkyl side chains of P3HT and PSLG were the main driving force for P3HT chain ordering into the crystalline assemblies.

Imaging optical scattering of butterfly wing scales with a microscope.

A new optical method is proposed to investigate the reflectance of structurally coloured objects, such as butterfly wing scales and cholesteric liquid crystals. Using a reflected-light microscope and a digital single-lens reflex (DSLR) camera, we have successfully measured the two-dimensional reflection pattern of individual wing scales of butterflies. We demonstrate that this method enables us to measure the bidirectional reflectance distribution function (BRDF).

Clinical significance of overexpression of NRG1 and its receptors, HER3 and HER4, in gastric cancer patients.

Background: Neuregulin 1 (NRG1), a ligand for human epidermal growth factor (HER) 3 and HER4, can activates cell signaling pathways to promote carcinogenesis and metastasis.

Methods: To investigate the clinicopathologic significance of NRG1 and its receptors, immunohistochemistry was performed for NRG1, HER3, and HER4 in 502 consecutive gastric cancers (GCs). Furthermore, HER2, microsatellite instability (MSI), and Epstein-Barr virus (EBV) status were investigated.

Using chiral tactoids as optical probes to study the aggregation behavior of chromonics.

Tactoids are nuclei of an orientationally ordered nematic phase that emerge upon cooling the isotropic phase. In addition to providing a natural setting for exploring chromonics under confinement, we show that tactoids can also serve as optical probes to delineate the role of temperature and concentration in the aggregation behavior of chromonics. For high concentrations, we observe the commonly reported elongated bipolar tactoids.

Enhanced Alignment of Water-Soluble Polythiophene Using Cellulose Nanocrystals as a Liquid Crystal Template.

Cellulose nanocrystals (CNCs) are bioderived, rodlike particles that form a chiral nematic liquid crystal (LC) in water. In this work, CNCs were used to induce long-range order in a semiconducting polymer, poly[3-(potassium-4-butanoate) thiophene-2,5-diyl] (PPBT). When mixed with CNCs, it was found that PPBT was incorporated into the liquid crystal "template" to form ordered structures with highly birefringent domains, as observed under polarized light.

Orientational Order of a Lyotropic Chromonic Liquid Crystal Measured by Polarized Raman Spectroscopy.

Lyotropic chromonic liquid crystals are distinct from thermotropic nematics from a fundamental standpoint as the structure of the aggregating columns is a function of both the temperature and concentration. We report on the thermal evolution of orientational order parameters, both the second (=scalar) (⟨P200⟩ (=S)) and fourth (⟨P400⟩) order, of sunset yellow FCF aqueous solutions, measured using polarized Raman spectroscopy for different concentrations. The order parameter increases with the concentration, and their values are high in comparison with those of thermotropic liquid crystals.

Macroscopic alignment of chromonic liquid crystals using patterned substrates.

We demonstrate an efficient technique to align lyotropic chromonic liquid crystals (LCLCs) using secondary sputtering lithography (SSL). Monodomains of LCLCs prepared using SSL maintained their stable alignment for days. A generalization of Berreman's theory was employed to determine the anchoring strength of LCLCs on tessellated surface patterns.

Spontaneous emergence of chirality in achiral lyotropic chromonic liquid crystals confined to cylinders.

The presumed ground state of a nematic fluid confined in a cylindrical geometry with planar anchoring corresponds to that of an axial configuration, wherein the director, free of deformations, is along the long axis of the cylinder. However, upon confinement of lyotropic chromonic liquid crystals in cylindrical geometries, here we uncover a surprising ground state corresponding to a doubly twisted director configuration. The stability of this ground state, which involves significant director deformations, can be rationalized by the saddle-splay contribution to the free energy.

Disclination elastica model of loop collision and growth in confined nematic liquid crystals.

Theory and modeling are used to characterize disclination loop-loop interactions in nematic liquid crystals under capillary confinement with strong homeotropic anchoring. This defect process arises when a mesogen in the isotropic phase is quenched into the stable nematic state. The texture evolution starts with +1/2 disclination loops that merge into a single loop through a process that involves collision, pinching and relaxation.

Enhanced mobility and effective control of threshold voltage in P3HT-based field-effect transistors via inclusion of oligothiophenes.

Improved organic field-effect transistor (OFET) performance through a polymer-oligomer semiconductor blend approach is demonstrated. Incorporation of 2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene (BTTT) into poly(3-hexylthiophene) (P3HT) thin films leads to approximately a 5-fold increase in charge carrier mobility, a 10-fold increase in current on-off ratio, and concomitantly, a decreased threshold voltage to as low as 1.7 V in comparison to single component thin films.

Theoretical predictions of disclination loop growth for nematic liquid crystals under capillary confinement.

The combination of low elasticity modulus, anisotropy, and responsiveness to external fields drives the rich variety of experimentally observed pattern formation in nematic liquid crystals under capillary confinement. External fields of interest in technology and fundamental physics are flow fields, electromagnetic fields, and surface fields due to confinement. In this paper we present theoretical and simulation studies of the pattern formation of nematic liquid crystal disclination loops under capillary confinement including branching processes from a m=+1 disclination line to two m=+1/2 disclination curves that describe the postnucleation and growth regime of the textural transformation from radial to planar polar textures.

Performance characteristics of nested polymerase chain reaction vs real-time polymerase chain reaction methods for detecting Mycobacterium tuberculosis complex in paraffin-embedded human tissues.

Objectives: Nucleic acid amplification tests on formalin-fixed, paraffin-embedded (FFPE) tissue specimens enable Mycobacterium tuberculosis complex (MTB) detection and rapid tuberculosis diagnosis in the absence of microbiologic culture tests. We aimed to evaluate the efficacy of different polymerase chain reaction (PCR) methods for detecting Mycobacterium species in FFPE tissues.

Methods: We examined 110 FFPE specimens (56 nonmycobacterial cases, 32 MTB, and 22 nontuberculous mycobacteria [NTM] determined by acid-fast bacilli [AFB] culture) to assess five PCR methods: nested PCR (N-PCR) (Seeplex MTB Nested ACE Detection; Seegene, Seoul, South Korea), an in-house real-time PCR (RT-PCR) method, and three commercial RT-PCR methods (AccuPower MTB RT-PCR [Bioneer, Seoul, Korea], artus M tuberculosis TM PCR [Qiagen, Hilden, Germany], and AdvanSure tuberculosis/NTM RT-PCR [LG Life Sciences, Seoul, Korea]).

Mechanisms and shape predictions of nematic disclination branching under conical confinement.

Liquid crystals (LCs) are self-organizing anisotropic viscoelastic soft materials that flow like viscous liquids and display anisotropies like crystals. When a nematic liquid crystal is confined to a capillary tube with strong anchoring conditions, disclination defects of higher (+1) and lower (+1/2) topological charges can coexist, connected through a defect branch point. The shape of the +1/2 disclination lines emanating from the branch point are functions of confinement and bulk elasticity.

Identification and characterization of proteins isolated from microvesicles derived from human lung cancer pleural effusions.

Microvesicles (MVs, also known as exosomes, ectosomes, microparticles) are released by various cancer cells, including lung, colorectal, and prostate carcinoma cells. MVs released from tumor cells and other sources accumulate in the circulation and in pleural effusion. Although recent studies have shown that MVs play multiple roles in tumor progression, the potential pathological roles of MV in pleural effusion, and their protein composition, are still unknown.

Rapid, sensitive, and specific detection of Mycobacterium tuberculosis complex by real-time PCR on paraffin-embedded human tissues.

The detection of Mycobacterium tuberculosis complex (MTB) in clinical specimens is important for diagnosing and caring for patients in whom tuberculosis is clinically suspected. We collected 129 FFPE specimens, including 56 nontuberculosis cases, 63 MTB cases, and 10 nontuberculous mycobacteria (NTM) cases determined by acid-fast bacilli (AFB) culture. We performed AFB staining; nested MTB PCR, targeting the IS6110 gene; and real-time MTB PCR, targeting the senX3-regX3 intergenic region in the 129 FFPE specimens.

Proteomic analysis of microvesicles derived from human colorectal cancer ascites.

The presence of malignant ascites in the peritoneal cavity is a poor prognostic indicator of low survival rate. Various cancer cells, including those of colorectal cancer (CRC), release microvesicles (exosomes) into surrounding tissues and peripheral circulation including malignant ascites. Although recent progress has revealed that microvesicles play multiple roles in tumor progression, the protein composition and the pathological function of malignant ascites-derived microvesicles are still unknown.

Solvent evaporation induced liquid crystalline phase in poly(3-hexylthiophene).

We report on the evolution of the chain orientation of a representative π-conjugated polymer, poly(3-hexylthiophene) (P3HT), during the solution-casting process, as monitored using polarized Raman spectroscopy. These measurements point to the formation of a liquid-crystalline phase of P3HT solutions within a specific time period during solvent evaporation, which leads to a conducting channel. These conclusions are based on the angular dependence of polarized Raman scattering peaks, the anisotropy in the fluorescence background signal, analysis of the scattering-peak shape, and direct observations of the three-phase contact line in an optical microscope under crossed polarizers.

Raman scattering study of phase biaxiality in a thermotropic bent-core nematic liquid crystal.

Polarized Raman spectroscopy was used to investigate the development of orientational order and the degree of phase biaxiality in a bent-core mesogenic system. The values of the uniaxial order parameters and , and biaxial order parameters , , and , and their evolution with temperature were determined. The temperature dependence of almost all order parameters reveals a second order transition from the uniaxial to biaxial nematic phase with increasing to ∼0.

Gram-positive bacteria produce membrane vesicles: proteomics-based characterization of Staphylococcus aureus-derived membrane vesicles.

Although archaea, Gram-negative bacteria, and mammalian cells constitutively secrete membrane vesicles (MVs) as a mechanism for cell-free intercellular communication, this cellular process has been overlooked in Gram-positive bacteria. Here, we found for the first time that Gram-positive bacteria naturally produce MVs into the extracellular milieu. Further characterizations showed that the density and size of Staphylococcus aureus-derived MVs are both similar to those of Gram-negative bacteria.

Structural origin of circularly polarized iridescence in jeweled beetles.

The iridescent metallic green beetle, Chrysina gloriosa, which selectively reflects left circularly polarized light, possesses an exoskeleton decorated by hexagonal cells (approximately 10 microm) that coexist with pentagons and heptagons. The fraction of hexagons decreases with an increase in curvature. In bright field microscopy, each cell contains a bright yellow core, placed in a greenish cell with yellowish border, but the core disappears in dark field.

Reliability of chromogenic in situ hybridization for epidermal growth factor receptor gene copy number detection in non-small-cell lung carcinomas: a comparison with fluorescence in situ hybridization study.

Fluorescence in situ hybridization (FISH) has been known to be the most representative and standardized test for assessing gene amplification. However, FISH requires a fluorescence microscope, the signals are labile and rapidly fade over time. Recently, chromogenic in situ hybridization (CISH) has emerged as a potential alternative to FISH.