Droplet-based biochemical assay by magnetic wire manipulation between multiple droplets

Reaction performance of a droplet-based biochemical assay technique that uses magnetic wires as sample carriers is evaluated. Wires 2.0 mm in length, 0.05 mm in width, and 0.02 mm in thickness are fabricated by chemical etching, introduced into a droplet immersed in oil, and manipulated by the magnetic force of a moving magnet. Alkaline-phosphatase as an enzyme is immobilized on the wire surfaces by applying Au and self-assembled monolayer coatings, and the method’s on-chip reaction performance is evaluated. The enzymatic reaction is found to increase linearly as the number of wires and the reaction time increase. Relatively high performance reproducibility for enzymatic reactions is obtained; on average, the reaction absorbance, standard deviation, and coefficient of variance are found to be respectively 1.14, 0.103, and 9.1 %. The conductivity change in a fused droplet is used to evaluate the absolute volume of liquid transferred with the extracted wires and a value of 0.33 μl is obtained.     

Properties of syndiotactic-rich poly(vinyl alcohol) thin film in water. V. Effect of initial temperature of heating on elongation

The effect of the initial temperature of heating on the elongation of syndiotactic-rich poly(vinyl alcohol) thin films was investigated in water under a load. The elongation ratios E_i after 4 h at fixed temperatures increased roughly with an increase in the initial temperature T_i and a decrease in the annealing temperature. E_i after 4 h was the smallest at T_i = 45°C for the films annealed at temperatures below 100°C. E_i was 6.8 at T_i = 60°C for the unannealed film and 1.12 at T_i = 70°C for the film annealed at 200°C. The elongation at break decreased and the temperature at break increased with an increase in annealing temperature, but those at the annealing temperature of 100°C were the smallest. The films annealed at 200°C did not break even at 98°C (boiling temperature) in water and the elongation ratio was 1.42–1.97 in the initial temperature range of 10–70°C. From these results, the relation between the elongation in water and the state of polymer chains in film was discussed.     

Improvement of characteristics of new-type solar cells, having a “transparent conductor/thin Si02 layer with ultrafine metal particles as conductive channels/n-Si” junction

New-type solar cells, having a structure “transparent conductor/thin Si0₂ layer with ultrafine metal islands as conductive channels/n-Si” have been prepared by forming a very thin (< 1.0 nm) silicon oxide (Si0₂) layer as well as platinum (Pt) islands (5–50 nm in size) embedded in it on a single crystal n-type silicon (n-Si) wafer, followed by the deposition of an indium tin oxide (ITO) film (200 nm thick) by the electron-beam evaporation method. The open-circuit photovoltages (V_oc) of the solar cells of the above structure were relatively low, 0.25–0.47 V, but they increased very much to 0.50–0.59 V if a thin (3–10 nm) layer of an organic compound such as copper phthalocyanine (CuPc) was pre-deposited on the Pt-island modified n-Si wafer before the ITO deposition. The reason for the beneficial effect of the pre-deposition of the thin CuPc layer was investigated in detail, and it has been found that certain crystal defects are formed in n-Si near the n-Si/Si0₂ interface during the ITO deposition in the absence of the CuPc layer. The formation of such defects is prevented in the presence of the CuPc layer, which leads to a decrease in surface carrier recombination and hence to the increase in V_oc.     

A chemically amplified molecular glass resist with an ionic photoacid generator and a single protection group

A molecular glass resist with an ionic photoacid generator and a single protection group (MR‐1) has been developed. MR‐1 exhibited good thermal properties, such as a 5% weight loss temperature (T_d5%) of 167°C and a glass transition temperature (T_g) of 80°C. MR‐1 showed the good sensitivity of 80 μC/cm² and high contrast of 4.9 with e‐beam exposure (50 keV). A relatively high resolution of 50 nm and low Line‐Edge‐Roughness of 3.8 nm were obtained by e‐beam exposure (100 keV). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39769.     

Calibration method for a carbon nanotube field-effect transistor biosensor

An easy calibration method based on the Langmuir adsorption theory is proposed for a carbon nanotube field-effect transistor (NTFET) biosensor. This method was applied to three NTFET biosensors that had approximately the same structure but exhibited different characteristics. After calibration, their experimentally determined characteristics exhibited a good agreement with the calibration curve. The reason why the observed characteristics of these NTFET biosensors differed among the devices was that the carbon nanotube (CNT) that formed the channel was not uniform. Although the controlled growth of a CNT is difficult, it is shown that an NTFET biosensor can be easy calibrated using the proposed calibration method, regardless of the CNT channel structures.     

A new method of reinforcing graphene nanoplatelets in glass/epoxy composites

This research aims to develop a method for the amalgamation of graphene nanoplatelets in glass/epoxy composites. The poor interface bonding between the fiber and matrix is critical and hinders the full performance of the composites. Glass fabric and epoxy were used as reinforcement and matrix in the composite, respectively. Graphene nanoplatelets were utilized as an additional nano-materials filler for the composites. Glass/graphene/epoxy and glass/epoxy composites were fabricated via vacuum infusion molding. The new method of applying graphene nanoplatelets as secondary reinforcement in the composite was developed based on proper functionalization in the sonication process. The physical, tensile, flexural, and short beam interlaminar properties of fabricated composites were examined to analyze the method's effectiveness. The results showed that density decreased by around 5 %; however, thickness increased by around 34 % after introducing graphene nanoplatelets into the composites. The tensile strength and modulus of the composites declined by approximately 19 %, on the other hand, flexural strength and modulus increased by around 63.3 % and 8.3 %, respectively, after the addition of graphene nanoplatelets into the composites. Moreover, interlaminar shear strength of the composite was enhanced by approximately 50 %.     

Preparation of Au-loaded niobate nanosheets and their plasmon-driven photochemical reaction

Niobate nanosheets prepared by exfoliation of layered hexaniobate K₄Nb₆O₁₇ were sequentially decorated with two noble metal nanoparticles, gold and silver, through two-step photochemical reactions. First, cationic bis(ethylenediamine)gold(III) ions were electrostatically adsorbed on the anionic niobate nanosheets, and reduced to gold nanoparticles by UV excitation of the photocatalytically active niobate nanosheets. Then, the surface plasmon band of the photodeposited gold nanoparticles was excited with visible light, by which the silver cations introduced to the system together with citrate anions were reduced to silver nanoparticles. Spectroscopic and transmission electron microscopic observations indicated the formation of morphologically different silver nanoparticles, for example nanorods and core-shell particles.