Dependence of the resultant Seebeck coefficient on the thickness of Bi<Subscript>0.88</Subscript>Sb<Subscript>0.12</Subscript> alloy in welded M/Bi–Sb/M (M = Cu and Ni) composites

The local Seebeck coefficient α _L and the resultant Seebeck coefficient α _R of M/Bi_0.88Sb_0.12/M (M = Cu and Ni) composites with different thicknesses t _Bi–Sb of Bi–Sb alloy were measured as functions of z and T, where T is the absolute temperature, z is the distance from a center of Bi–Sb alloy to the middle point of two probes and α _L and α _R were measured using two probes separated by s=1.0 mm and s=t _Bi−Sb+0.1 mm, respectively. As a result, α _L was enhanced extremely at the position of 0.2–0.3 mm away from the interfaces, while the local temperature along a composite varies linearly with changes in z within Bi–Sb alloy. The local maximum of α _R at 344 K appeared at t _Bi−Sb≈0.9 mm, so that it is expected to increase up to −167 μV/K at t _Bi−Sb=0.87 mm from the expression fitted well to the experimental data, which is 2.1 times as large as the intrinsic α at 344 K of Bi–Sb alloy. Such a local enhancement in α _L would probably be caused by a temperature gradient across the depletion layer formed at the interface. The thermoelectric figure of merit ZT of a composite with an optimum t _Bi−Sb of 0.87 mm is expected to reach the large value of 0.98 at 344 K, which corresponds to 4.5 times as high a value as ZT=0.22 at 344 K of Bi–Sb alloy. It is thus considered that the increase in α _L at the interface is available as a useful mean of further increase in ZT of thermoelectric devices.     

Synthesis, crystal structure and characterization of iron pyroborate (Fe2B2O5) single crystals

Single crystals of iron(II) pyroborate, Fe₂B₂O₅, were prepared at 1000–1050 °C under an argon atmosphere. The crystals were transparent, yellowish in color and needle-like or columnar. The crystal structure of Fe₂B₂O₅ was analyzed by single-crystal X-ray diffraction. Refined triclinic unit cell parameters were a=3.2388(2), b=6.1684(5), c=9.3866(8) Å, α=104.613(3)°, β=90.799(2)° and γ=91.731(2)°. The final reliability factors of refinement were R1=0.020 and wR2=0.059 [I > 2σ(I)]. Transmittance over 50% in the visible light region from 500 to 750 nm was observed for a single crystal of Fe₂B₂O₅ with a thickness of about 0.3 mm. The light absorption edge estimated from a diffuse reflectance spectrum was at around 350 nm (3.6 eV). Magnetic susceptibility was measured for single crystals at 4–300 K. Fe₂B₂O₅ showed antiferromagnetic behavior below the Néel temperature, T_N≈70 K, and the Weiss temperature was T_W=36 K. The effective magnetic moment of Fe was 5.3μ_B.     

Synthesis of phosphorylcholine-oligoethylene glycol-alkane thiols and their suppressive effect on non-specific adsorption of proteins

A series of phosphorylcholine-oligoethylene glycol-alkane thiols were synthesized, and their suppressive effect on the non-specific adsorption of proteins was evaluated by comparison with corresponding oligoethylene glycol-alkane thiols. It was found that phosphorylcholine-oligoethylene glycol-alkane thiols had a greater suppressive effect on the non-specific adsorption of proteins.     

Asymptotic energy concentration in the phase space of the weak solutions to the Navier-Stokes equations

We study the asymptotic behavior of the energy of weak solutions of Navier-Stokes equations as t→∞. We characterize the space of the initial data which causes a concentration of the kinetic energy in the phase space. Moreover, an explicit convergence rate is obtained.     

Stability of ribonuclease A under hydrothermal conditions in relation to the origin-of-life hypothesis: verification with the hydrothermal micro-flow reactor system

The stability of ribonuclease A (RNase A) was quantitatively investigated with the hydrothermal micro-flow reactor system (HFRS) at temperatures of up to 275 °C from the viewpoint of the hydrothermal origin-of-life hypothesis. The enzymatic activity of RNase A was studied with regard to the catalytic degradation of polynucleotides with anion-exchange high-performance liquid chromatography, while the degradation of RNase A to shorter molecules was analyzed by size exclusion chromatography (SEC) and mass spectrometry (MS). The degradation of RNase A started within 10 s at 200 °C, and the enzymatic activity disappeared almost completely after 25 s. SEC and MS analyses indicated that RNase A was thermally degraded to 2 large fragments, which, along with RNase A, were further decomposed to smaller fragments. This study showed that RNase A is fairly stable under normal conditions, but its enzymatic activity disappears rapidly at extremely high temperatures. The half life of RNase A and its fragments under hydrothermal conditions is comparable to or longer than the enzymatic reaction time scale of modern enzymes. Furthermore, this study demonstrates that HFRS is reliable and useful for verifying the stability of several proteins in fundamental and applied research as well as for studying the origin-of-life problem.     

Polymer electrolytes based on vinyl ethers with various EO chain length and their polymer electrolytes cross-linked by electron beam irradiation

Polymer electrolytes based on vinyl ethers with various ethyleneoxy (EO) chain length (poly-1a (m?=?3), poly-1b (m?=?6), poly-1c (m?=?10), and poly-1d (m?=?23.5)) with lithium bis(trifluoromethanesulfonimide) (LiTFSI) were prepared, and effect of pendant EO chain length in the polymers on electrochemical and thermal properties was investigated. Glass transition temperature (T _g) of all polymer electrolytes increased linearly with an increase in salt concentrations. Ionic conductivities of the polymer electrolytes increased with an increase in the pendant EO chain length of the polymers at the constant [Li]/[O] ratio, but in the polymer electrolyte of the poly-1d (m?=?23.5) with the longest pendant EO chain length, ionic conductivity decreased in the low temperature range of ?20 to 10 °C due to the crystallization of the pendant EO chain. The highest ionic conductivity, 1.23?×?10^?4 S/cm at 30 °C, was obtained in the polymer electrolyte of the poly-1c (m?=?10) with pendant EO chain length of 10 at the [Li]/[O] ratio of 1/20. It was found that the cross-linking of the polymer electrolyte, composed of poly-1c (m?=?10) with LiTFSI at the [Li]/[O] ratio of 1/28, by electron beam (EB) irradiation may improve the mechanical property without affecting ionic conductivity, thermal property, and oxidation stability. Polymer electrolytes based on poly-1a (m?=?3), poly-1b (m?=?6), poly-1c (m?=?10), and poly-1d (m?=?23.5) and cross-linked polymer electrolytes were electrochemically stable until 4 V and thermally stable around 300 °C.     

Live cell refractometry using microfluidic devices

Using Hilbert phase microscopy for extracting quantitative phase images, we measured the average refractive index associated with live cells in culture. To decouple the contributions to the phase signal from the cell refractive index and thickness, we confined the cells in microchannels. The results are confirmed by comparison with measurements of spherical cells in suspension.     

Phase synchronization between collective rhythms of globally coupled oscillator groups: noisy identical case

We theoretically investigate the collective phase synchronization between interacting groups of globally coupled noisy identical phase oscillators exhibiting macroscopic rhythms. Using the phase reduction method, we derive coupled collective phase equations describing the macroscopic rhythms of the groups from microscopic Langevin phase equations of the individual oscillators via nonlinear Fokker-Planck equations. For sinusoidal microscopic coupling, we determine the type of the collective phase coupling function, i.e., whether the groups exhibit in-phase or antiphase synchronization. We show that the macroscopic rhythms can exhibit effective antiphase synchronization even if the microscopic phase coupling between the groups is in-phase, and vice versa. Moreover, near the onset of collective oscillations, we analytically obtain the collective phase coupling function using center-manifold and phase reductions of the nonlinear Fokker-Planck equations.     

Exceeding Metal Capacity in Sandwich Complexes: Ligand‐Unsupported Docking of Extra Metal Moieties at Edges of a Metal Sheet Sandwich Complex

The ligand‐unsupported accommodation of extra metal moieties in a sandwich complex is reported. Although it has been considered that the metal‐capacity of a metal sheet sandwich complex is strictly limited by the size of cyclic unsaturated hydrocarbon ligands, the M?M edge bonds in a metal sheet sandwich complex provide a ligand‐unsupported docking site for extra metal moieties, allowing expansion of metal‐capacity in sandwich complexes. The metal sheet sandwich complex [Pd₄(μ₄‐C₈H₈)(μ₄‐C₉H₉)]⁺, in which the ligand‐based metal capacity is full in terms of the usage of all C=C moieties of the smaller carbocyclic ligand C₈H₈ in coordination, can accommodate extra M⁰{P(OPh)₃}₂ (M=Pd, Pt) moieties without coordinative assistance by either the C₉H₉ or the C₈H₈ ligand.