Rapid detection of a cocaine-binding aptamer using biological nanopores on a chip

This paper describes a methodology for the rapid and highly selective detection of cocaine using a membrane protein channel combined with a DNA aptamer. The DNA aptamer recognizes the cocaine molecule with high selectivity. We successfully detected a low concentration of cocaine (300 ng/mL, the drug test cutoff limit) within 60 s using a biological nanopore embedded in a microchip.     

Near-Infrared Chemometric Approach to Exhaustive Analysis of Rice Straw Pretreated for Bioethanol Conversion

We report a simple analytical procedure combining near-infrared (NIR) spectroscopy with multivariate analysis to detect the saccharification efficiency of pretreated rice straw. Three types of sample preparation methods were tested to develop a powerful calibration model, with the disk sample used as the standard protocol. From the spectra dataset of NaOH-treated biomass, we obtained a good calibration for the saccharification ratio and some major structural components by partial least-squares regression. Adding dataset from hot water and dilute sulfuric acid pretreatments to NaOH sample dataset, an acceptable calibration model to predict the saccharification ratio as well as the glucose, xylose, and lignin contents was generated. NIR has a great potential for rapid screening of saccharification efficiency of pretreated biomass, which would allows us to control the quality of processing toward better bioethanol production.     

Linear- and angular-shaped naphthodithiophenes: selective synthesis, properties, and application to organic field-effect transistors

A straightforward synthetic approach that exploits linear- and angular-shaped naphthodithiophenes (NDTs) being potential as new core structures for organic semiconductors is described. The newly established synthetic procedure involves two important steps; one is the chemoselective Sonogashira coupling reaction on the trifluoromethanesulfonyloxy site over the bromine site enabling selective formation of o-bromoethynylbenzene substructures on the naphthalene core, and the other is a facile ring closing reaction of fused-thiophene rings from the o-bromoethynylbenzene substructures. As a result, three isomeric NDTs, naphtho[2,3-b:6,7-b']dithiophene, naphtho[2,3-b:7,6-b']dithiophenes, and naphtho[2,1-b:6,5-b']dithiophene, are selectively synthesized. Electrochemical and optical measurements of the parent NDTs indicated that the shape of the molecules plays an important role in determining the electronic structure of the compounds; the linear-shaped NDTs formally isoelectronic with naphthacene have lower oxidation potentials and more red-shifted absorption bands than those of the angular-shaped NDTs isoelectronic with chrysene. On the contrary, the performance of the thin-film-based field-effect transistors (FETs) using the dioctyl or diphenyl derivatives were much influenced by the symmetry of the molecules; centrosymmetric derivatives tend to give higher mobility (up to 1.5 cm(2) V(-1) s(-1)) than axisymmetric ones (～0.06 cm(2) V(-1) s(-1)), implying that the intermolecular orbital overlap in the solid state is influenced by the symmetry of the molecules. These results indicate that the present NDT cores, in particular the linear-shaped, centrosymmetric naphtho[2,3-b:6,7-b']dithiophene, are promising building blocks for the development of organic semiconducting materials.     

Synthetic studies of the lichen macrolide lepranthin. Stereoselective synthesis of the diolide framework based on regioselective epoxide-opening reactions

Stereoselective synthesis of the 16-membered diolide 27, a fully functionalized congener of lepranthin (1), is described. The requisite five asymmetric carbon centers in monomer 23 were constructed in a highly stereoselective manner by using different epoxide-opening reactions of α,β-unsaturated γ,δ-epoxy esters and epoxy alcohol derivatives as the key steps. The monomer 23 was successfully transformed into the MOM protected diolide 27 by Yamaguchi macrolactonization.     

Hydrostatic pressure reveals bilayer phase behavior of dioctadecyldimethylammonium bromide and chloride

Bilayer phase transitions of dioctadecyldimethylammonium bromide (2C(18)Br) and chloride (2C(18)Cl) were observed by differential scanning calorimetry and high-pressure light-transmittance measurements. The 2C(18)Br bilayer membrane showed different kinds of transitions depending on preparation methods of samples under atmospheric pressure. Under certain conditions, the 2C(18)Br bilayer underwent three kinds of transitions, the metastable transition from the metastable lamellar crystal (L(c(2))) phase to the metastable lamellar gel (L(β)) phase at 35.4 °C, the metastable main transition from the metastable L(β) phase to the metastable liquid crystalline (L(α)) phase at 44.5 °C, and the stable transition from the stable lamellar crystal (L(c(1))) phase to the stable L(α) phase at 52.8 °C. On the contrary, the 2C(18)Cl bilayer underwent two kinds of transitions, the stable transition from the stable L(c) phase to the stable L(β) phase at 19.7 °C and the stable main transition from the stable L(β) phase to the stable L(α) phase at 39.9 °C. The temperatures of the phase transitions of the 2C(18)Br and 2C(18)Cl bilayers were almost linearly elevated by applying pressure. It was found from the temperature (T)-pressure (p) phase diagram of the 2C(18)Br bilayer that the T-p curves for the main transition and the L(c(1))/L(α) transition intersect at ca. 130 MPa because of the larger slope of the former transition curve. On the other hand, the T-p phase diagram of the 2C(18)Cl bilayer took a simple shape. The thermodynamic properties for the main transition of the 2C(18)Br and 2C(18)Cl bilayers were comparable to each other, whereas those for the L(c(1))/L(α) transition of the 2C(18)Br bilayer showed considerably high values, signifying that the L(c(1)) phase of the 2C(18)Br bilayer is extremely stable. These differences observed in both bilayers are attributable to the difference in interaction between a surfactant and its counterion.     

Visualization of aggregation process of dispersed water droplets and the effect of aggregation on secondary atomization of emulsified fuel droplets

The effect of aggregation of dispersed water droplets on secondary atomization of emulsified fuel droplets in a heating process was investigated. Secondary atomization was observed using a single droplet experiment in which a water-in-oil (W/O) emulsified fuel droplet prepared using colored water was heated by a halogen heater. The initial diameter of dispersed water droplets before heating was controlled, and the change in the diameter of dispersed water droplets was measured by image analysis. As a result, the aggregation process of dispersed water droplets in the heating process was successfully visualized. The dispersed water droplet diameter increased with an increase in W/O emulsified fuel droplet temperature. The occurrence probability of micro-explosion increased with an increase in the dispersed water droplet diameter in emulsified fuel droplets. It is suggested that the occurrence probability of micro-explosion can be increased by accelerating the aggregation and coalescence of dispersed water droplets below 430 K, which is the average temperature of the starting point of puffing.     

Existence of an exceptional reaction pathway for H3(+) formation observed in collision-induced dissociation of methane ions at 1000 eV

Dissociation of CH(4)(+) ions at 1000 eV induced by collision with Ar atoms was investigated by measuring the kinetic energies of the ionized fragments. At small scattering angles, including zero, H(+), H(2)(+), H(3)(+), CH(3)(+), CH(2)(+), CH(+), and C(+) fragments were observed. The attractive part of the potential in the CH(4)(+)-Ar collision system played an important role in the formation of the ionized fragments. Rainbow scattering, leading to a large scattering cross section, was shown to be responsible for the increased formation of H(3)(+). It is proposed that on collision-induced dissociation of CH(4)(+), its three hydrogen atoms, which form a triangle, simultaneously react and move together to form H(3)(+).     

Water irradiation by high-frequency ultrasonic wave: effects on properties of passive film formed on stainless steel

In this paper an aqueous solution was irradiated with a 1.63MHz ultrasonic wave. It is shown that if stainless steel can passivate under dynamic polarization in this medium, under static polarization, the latter does not show any repassivation behaviour with time. This is attributed to a diminution of the diffusion layer thickness that is developed at the electrode/electrolyte interface, which is associated with a production of H(2) species by sonolysis and which maintains reductive conditions at the interface. The oxide film formed under ultrasonic irradiation for 1h at a passive potential of+0.2V(SCE) shows an early stage of passivation and an increased disordered state, which implies a considerable decrease in the corrosion resistance behaviour of the sample. The polarization resistance of the stainless steel R(p) is divided by a value of 4.5 under ultrasonic conditions.     

A spectral invariant representation of spectral reflectance

Spectral image acquisition as well as color image is affected by several illumination factors such as shading, gloss, and specular highlight. Spectral invariant representations for these factors were proposed for the standard dichromatic reflection model of inhomogeneous dielectric materials. However, these representations are inadequate for other characteristic materials like metal. This paper proposes a more general spectral invariant representation for obtaining reliable spectral reflectance images. Our invariant representation is derived from the standard dichromatic reflection model for dielectric materials and the extended dichromatic reflection model for metals. We proof that the invariant formulas for spectral images of natural objects preserve spectral information and are invariant to highlights, shading, surface geometry, and illumination intensity. It is proved that the conventional spectral invariant technique can be applied to metals in addition to dielectric objects. Experimental results show that the proposed spectral invariant representation is effective for image segmentation.     

Efficient waveguide-type four-color (red–green–blue–infrared) laser beam combiner for compact laser beam scanning image projectors

Optical Review - A waveguide-based combiner that can combine an infrared laser beam with primary color (red, green, and blue) laser beams is proposed and analyzed using a simulation based on the...