Terahertz surface-wave resonant sensor with a metal hole array

A surface-wave sensor based on the resonant transmission characteristics of metal hole arrays is demonstrated in the terahertz (THz) region. Since the frequency of the transmission peak of a metal hole array, which corresponds to the resonant frequency of the surface waves, is particularly sensitive to the refractive index in the vicinity of the metal surface, a very small change in the substances attached to the surface can be detected by monitoring the transmission spectrum. By attaching a layer of substance (thickness t < 5 microm) much thinner than the wavelength of the THz wave (lambda(THz) = 1 mm at 0.3 THz) to the surface of a metal hole array, we demonstrated that the existence of such a small amount of substance can be detected more easily than without the metal hole array. This demonstration of THz sensing with metal hole arrays indicates the possibility of realizing THz surface-wave sensors for biochemical molecules in the THz region.     

Effects of alcohols on multi-bubble sonoluminescence spectra

Spectra of multi-bubble sonoluminescence (MBSL) were measured in argon-saturated water and ethanol solutions in the concentration range 2-100 mM at the frequencies of 116 kHz and 1.0 MHz. The spectral peaks from OH-radical emission near 310 nm were observed at relatively low ultrasonic power at both frequencies. The sub-peaks at 290 and 340 nm were also observed, which are attributed to OH-radical vibronic transition. The MBSL spectra from ethanol solutions indicated that the quenching of OH-radical emission was more efficient than that of underlying continuous spectrum. The continuous spectrum suggested the decrease in temperature with increasing ethanol concentration. The concentration dependence of spectrum quenching showed no frequency dependence. A new peak was observed at 385 nm only at small ethanol concentrations and at the frequency of 1.0 MHz, which attributed to CH or CN molecule emission.     

Limiting behavior of relative Rényi entropy in a non-regular location shift family

We calculate the limiting behavior of relative Rényi entropy between adjacent two probability distribution in a non-regular location-shift family which is generated by a probability distribution whose support is an interval or a half-line. This limit can be regarded as a generalization of Fisher information, and seems closely related to information geometry and large deviation theory.     

Asymptotics of solutions to the periodic problem for the nonlinear damped wave equation

We study large time asymptotic behavior of solutions to the periodic problem for the nonlinear damped wave equation

Generating Boundary Conditions for the Calculation of Tsunami Propagation on Nested Grids

Some boundary conditions used to numerically simulate tsunami generation and propagation are studied. Special attention is given to generating boundary conditions thatmake it possible to simulate tsunami waves with desired characteristics (amplitude, time period and, in general, waveform). Since the water flow velocity in a propagating tsunami wave is uniquely defined by its height and ocean depth, one can simulate a wave propagating from the boundary into the simulation area. This can be done by specifying the wave height and water flow velocity on the boundary. This method is used to numerically simulate the propagation of a tsunami from the source to the coast on a sequence of refined grids. In this numerical experiment the wave parameters are transferred from the larger area to the subarea via boundary conditions. This method can also generate a wave that has certain characteristics on a specified line.     

Computational studies on electron and proton transfer in phenol‐imidazole‐base triads

The electron and proton transfer in phenol‐imidazole‐base systems (base = NH₂^? or OH^?) were investigated by density‐functional theory calculations. In particular, the role of bridge imidazole on the electron and proton transfer was discussed in comparison with the phenol‐base systems (base = imidazole, H₂O, NH₃, OH^?, and NH₂^?). In the gas phase phenol‐imidazole‐base system, the hydrogen bonding between the phenol and the imidazole is classified as short strong hydrogen bonding, whereas that between the imidazole and the base is a conventional hydrogen bonding. The n value in spⁿ hybridization of the oxygen and carbon atoms of the phenolic CO sigma bond was found to be closely related to the CO bond length. From the potential energy surfaces without and with zero point energy correction, it can be concluded that the separated electron and proton transfer mechanism is suitable for the gas‐phase phenol‐imidazole‐base triads, in which the low‐barrier hydrogen bond is found and the delocalized phenolic proton can move freely in the single‐well potential. For the gas‐phase oxidized systems and all of the triads in water solvent, the homogeneous proton‐coupled electron transfer mechanism prevails. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

The development of a knowledge base for basic active structures: an example case of dopamine agonists

Background  

Chemical compounds affecting a bioactivity can usually be classified into several groups, each of which shares a characteristic substructure. We call these substructures "basic active structures" or BASs. The extraction of BASs is challenging when the database of compounds contains a variety of skeletons. Data mining technology, associated with the work of chemists, has enabled the systematic elaboration of BASs.     

Structure conversions of cellulose IIII crystal models in solution state: a molecular dynamics study

This paper re-examines our previous molecular dynamics (MD) study on cellulose III_I crystal models with finite dimensions solvated in explicit water molecules. Eight crystal models, differing in a constituent lattice plane and dimensions, were studied. One calculation allowed for O–H and C–H bond stretching, and had a small time step of 0.5 fs. The other calculation adopted non-scaling factors of the 1–4 non-bonded interactions. As in our previous study, in the former MD calculations, six of the eight crystal models exhibited structure conversion with cooperative chain slippages generated by a progressive fiber bend. This converted the initial non-staggered chain packing of cellulose III_I into a near one-quarter staggering and gave the crystal model a triclinic-like configuration. In contrast, in the non-1–4 scaling MD calculations, all of the eight crystal models retained the initial cellulose III_I crystal structure. Another series of non-1–4 scaling MD calculations were performed for the four crystal models containing chains with a degree of polymerization (DP) of 40 at 370 K, which simulated hot water treatment to convert cellulose III_I to Iβ. Some of the hydroxymethyl groups irreversibly rotated from gt into tg conformation. This accompanied exchange of the intrasheet hydrogen bonding scheme along the (1 ?1 0) lattice plane from O2–O6 to O3–O6. The original corrugated (1 ?1 0) chain sheet was partly converted into a cellulose I-like flat chain sheet.     

Supramolecular hemoprotein-gold nanoparticle conjugates

Interaction of apohemoprotein with a covalently immobilized heme moiety onto a gold nanoparticle surface resulted in supramolecular hemoprotein-gold nanoparticle conjugates. The addition of an apohemoprotein dimer further led to a densely-packed hemoprotein-gold nanoparticle assembly, which was visualized by TEM and AFM measurements.     

Observation of mechanically induced luminescence from microparticles

We have invented a new device based on atomic force microscopy that measures the emission from a single microparticle by force direct application using the AFM probe, and successfully observed emission in the region of the elastic deformation, friction, and destructive deformation.