Minitwistor spaces,Severi varieties,and Einstein–Weyl structure

In this article, we show that the space of nodal rational curves, which is so called a Severi variety (of rational curves), on any non-singular projective surface is always equipped with a natural Einstein–Weyl structure, if the space is 3-dimensional. This is a generalization of the Einstein–Weyl structure on the space of smooth rational curves on a complex surface, given by Hitchin. As geometric objects naturally associated to Einstein–Weyl structure, we investigate null surfaces and geodesics on the Severi varieties. Also, we see that if the projective surface has an appropriate real structure, then the real locus of the Severi variety becomes a positive definite Einstein–Weyl manifold. Moreover, we construct various explicit examples of rational surfaces having 3-dimensional Severi varieties of rational curves.     

Design of chemical shift-switching 19F magnetic resonance imaging probe for specific detection of human monoamine oxidase A

Monoamine oxidase (MAO) A is a flavoenzyme that catalyzes the oxidation of biologically important monoamines and is thought to be associated with psychiatric disorders. Here, we report a strategy for rationally designing a (19)F magnetic resonance imaging probe for the specific detection of human MAO-A (hMAO-A) activity. Our designed (19)F probe was oxidized expeditiously by hMAO-A to produce 2-fluoro-4-nitrophenol via a spontaneous β-elimination mechanism. Concomitant with the structural change of the probe to the product, the (19)F chemical shift changed by 4.2 ppm, which was enough to visualize the probe and enzymatic product separately. Importantly, our probe achieved excellent discrimination of hMAO-A from its isoform hMAO-B.     

Microencapsulation of TiO2 Nanoparticles with Polymer by Rapid Expansion of Supercritical Solution

A novel preparation method is reported for the microencapsulation of TiO₂ nanoparticles by rapid expansion of supercritical solution with a nonsolvent. A suspension of TiO₂ nanoparticles in carbon dioxide containing a cosolvent and dissolved polymer is sprayed through a nozzle to atmospheric pressure. After rapid expansion, polymer microspheres were obtained. The microspheres do not tend to agglomerate, since the pure cosolvent is a nonsolvent for the polymer. The structure and morphology of microspheres were investigated by SEM, TEM and XRD. The obtained polymer microspheres are microcapsules of TiO₂ nanoparticles. The mean particle diameter and particle size distribution of microcapsules, could be controlled by changing the polymer concentration, pre-expansion pressure, temperature and injection distance. The polymer feed compositions are more effective than other factors on the control of particle size.     

U(1) gauge-coupled Dirac equation and massless (QED)2 on a finite element

Toward the construction of the gauge theory on a lattice without species doubling, we formulate the U(1) gauge-coupled Dirac equation on a finite element in (d + 1)-dimensional space-time. For massless (QED)₂, we derive the vector current conservation and the axial anomaly. The reproduction of the axial anomaly indicates the resolution of the doubling problem.     

Spektroskopische Untersuchung der Prim?rprozesse bei der strahleninduzierten Polymerisation von 1,3-Butadien

Ohne Zusammenfassung     

Mössbauer spectroscopic study on polyacetylene doped with iodine

The ¹²⁹I Mössbauer effect has been applied to polyacetylene films of cis-(CHI_0.23)_x as prepared and cis-(CHI_0.20)_x led under dynamic evacuation. It has been clarified that both films contain linear I^?₅ and I^?₃ with symmetric charge population and that the fraction of I^?₃ increases after evacuation. The mechanism of electrical conductivity in iodine-doped polyacetylene has been discussed on the basis of the chemical form and the dynamic behavior of the anion species.     

Single-shot spectrometry for x-ray free-electron lasers

An experimental scheme to realize single-shot spectrometry for the diagnostics of x-ray free-electron lasers (XFELs) is presented. The combination of an ultraprecisely figured mirror and a perfect crystal form a simple, high-precision spectrometer that can cover an energy range from a few eV to a hundred eV with high resolution. The application of the spectrometer to determine XFEL pulse widths was investigated theoretically and experimentally. It has been shown that the present system can determine pulse widths from sub-fs to ps in a single shot even for spontaneous radiation. The system can be easily extended to even shorter pulses.     

Simple method for estimating shape functions of optical spectra

A simple method for estimating shape functions of optical spectra is proposed, based on the numerical correlation with an assumed optical spectrum composed of a central main rectangular component and two right-angled triangular wings on either side of the main component. The degrees of correlation between observed and assumed spectra were examined using spectral and coherence widths of those spectra and pulsewidths of Fourier-transform-limited pulses calculated from those spectra. By using this method, shape functions of output spectra from superluminescent diodes and a self-pulsating laser diode were evaluated in detail over a relatively wide injection current range beyond their rated currents.