Barium-filled skutterudites BayCo4Sb12 with an anomalously large filling fraction of up to y=0.44 have been synthesized. The lattice parameters increase linearly with Ba content. Magnetic susceptibility data show that Ba0.44Co4Sb12 is paramagnetic, which implies that some of the Co atoms in BayCo4Sb12 have acquired a magnetic moment. The presence of the two different valence states of Co (Co3+ and Co2+) leads to the anomalously large barium filling fraction even without extra charge compensation. All samples show n-type conduction. The electrical conductivity increases with increasing the Ba filling fraction. The lattice thermal conductivity of BayCo4Sb12 is significantly depressed as compared to unfilled Co4Sb12. The dimensionless thermoelectric figure of merit, ZT, increases with increasing temperature reaching a maximum value of 1.1 for Ba0.24Co4Sb12 at 850 K.

Te-doped CoSb3 bulk polycrystalline materials Co4Sb12−xTex have been prepared by melting, annealing, and spark plasma sintering and have been characterized by x-ray diffraction. From the lattice constants of the Te-doped samples, a Te substituting fraction limit for Sb is estimated to be x=0.55. The Hall effect, Seebeck coefficient, electrical-conductivity, and thermal-conductivity measurements were performed between room temperature and 900K. The Te-doped materials Co4Sb12−xTex show an n-type conduction. As the Te fraction increases, the electron concentration and the electrical conductivity of the samples increase, while the Hall mobility, the absolute Seebeck coefficient, and the thermal conductivity decrease. A maximum dimensionless figure of merit of 0.72 is obtained at 850K for Co4Sb11.5Te0.5.

Graphene has strong potential for electrical biosensing owing to its two-dimensional nature and high carrier mobility which transduce the direct contact of a detection target with a graphene channel to a large conductivity change in a graphene field-effect transistor (G-FET). However, the measurable range from the graphene surface is highly restricted by Debye screening, whose characteristic length is less than 1 nm at physiological ionic strength. Here, we demonstrated electrical biosensing utilizing the enzymatic products of the target. We achieved quantitative measurements of a target based on the site-binding model and real-time measurement of the enzyme kinetics in femtoliter microdroplets. The combination of a G-FET and microfluidics, named a “lab-on-a-graphene-FET”, detected the enzyme urease with high sensitivity in the zeptomole range in 100 mM sodium phosphate buffer. Also, the lab-on-a-graphene-FET detected the gastric cancer pathogen Helicobacter pylori captured at a distance greater than the Debye screening length from the G-FET.

We present the experimental framework for the origin of the anomalously large thermoelectric power for Si and Au-doped Ge superlattice thin film. The thermoelectric power of the sample still remains anomalously large even though the superlattice structure begins to collapse. An amorphous Ge thin film displays large thermoelectric power. The crystallized samples have almost the same thermoelectric power as that of conventional SiGe bulk samples. The main cause of this anomalously large thermoelectric power of Si/Ge superlattice thin films is amorphous Ge layer.

The thermoelectric properties of superlattice thin films have been studied as functions of temperature. The superlattice thin films were prepared by the alternate deposition of Si and Ge heavily doped with Au in ultrahigh vacuum. They have an intended artificial interval, but each layer is in an amorphous state. An anomalously large thermoelectric power and power factor is observed. The power factor reaches a maximum value of approximately 7 W/mK2 at around 800 K, which is anomalously large compared to that for conventional bulk materials.

There are global concerns about threat of pandemic caused by the human-infectious avian influenza virus. To prevent the oncoming pandemic, it is crucial to analyze the viral affinity to human-type or avian-type sialoglycans with high sensitivity at high speed. Graphene-FET (G-FET) realizes such high-sensitive electrical detection of the targets, owing to graphene’s high carrier mobility. In the present study, G-FET was functionalized using sialoglycans and employed for the selective detection of lectins from Sambucus sieboldiana and Maackia amurensis as alternatives of the human and avian influenza viruses. Glycan-functionalized G-FET selectively monitored the sialoglycan-specific binding reactions at subnanomolar sensitivity.

Influenza viruses cause a significant public health burden each year despite the availability of anti-influenza drugs and vaccines. Therefore, new anti-influenza virus agents are needed. Rhamnan sulfate (RS) is a sulfated polysaccharide derived from the green alga Monostroma nitidum. Here, we aimed to demonstrate the antiviral activity of RS, especially against influenza A virus (IFV) infection, in vitro and in vivo. RS showed inhibitory effects on viral proliferation of enveloped viruses in vitro. Evaluation of the anti-IFV activity of RS in vitro showed that it inhibited both virus adsorption and entry steps. The oral administration of RS in IFV-infected immunocompetent and immunocompromised mice suppressed viral proliferation in both mouse types. The oral administration of RS also had stimulatory effects on neutralizing antibody production. Fluorescent analysis showed that RS colocalized with M cells in Peyer's patches, suggesting that RS bound to the M cells and may be incorporated into the Peyer's patches, which are essential to intestinal immunity. In summary, RS inhibits influenza virus infection and promotes antibody production, suggesting that RS is a potential candidate for the treatment of influenza virus infections.

The novel hemagglutinin nucleotide sequences reported here were deposited in GISAID under the accession numbers of EPI685738 for A/Yamaguchi/20/2006(H1N1) and EPI685740 for A/Kitakyushu/10/2006(H1N1).