Real three-dimensional microstructures fabricated by photopolymerization of resins through two-photon absorption

Effective energy windows for two-photon absorption (TPA) photopolymerization of resins were investigated and, with a properly selected laser pulse energy, exquisite three-dimensional (3D) microstructures with submicrometer spatial resolution were achieved. The results show the inherent utility of TPA in the fabrication of real 3D patterns. In particular, we propose and utilize a resin pre-exposure technique by which freely movable components affixed to an axle are built, demonstrating a new application of TPA in laser microfabrication.     

Direct micropatterning of high dielectric BaTiO3 films by laser-induced pyrolysis with a nano-crystalline seeding technique

A direct patterning method of dielectric BaTiO₃ (BT) films is proposed, which applies laser-induced pyrolysis in combination with nano-crystalline seeding technique. A precursor solution of a BT complex alkoxide containing BT nano-crystalline particles with polyvinylpyrollidone (PVP) as dispersion stabilizer was spin-coated on Pt substrate. An Ar⁺ laser beam was focused and scanned on spin-coated BT films, which induced pyrolysis and crystallization of the films with spatial selectivity. Micropatterns were obtained by striping laser-unirradiated regions on the films with HCl aqueous solution. Raman spectra of the micropattern confirmed that the structures were tetragonal crystalline BT. Clear micropatterns with a line width of ca. 3 μm and an interval of 5 μm were formed at PVP concentrations of 25 and 50 kg/m³. The dielectric constant and dissipation factor of the film fabricated at a laser energy density of 27 MW/cm² and a scanning speed of 25 μm/s attained 76.2 and 0.07, respectively, for a measurement frequency of 100 kHz.     

Measurement of Gamma-Rays from 11ΛB and 12ΛC

From the ^12 C（π^＋,K^＋）^12 AC reaction the γ -rays of 261.6±0.24 ke V（7/2^＋ →5/2^＋）and 1481.7±0.7 ke V（1/2^＋ →5/2^＋） of ^11 A B,and 2667.3±2.8 keV（1^- 2 → 2^- 1）of ^12 A C hypernuclei have been identified using a large germanium detector array Hyperball2 at K6 beam line of KEK. The observed energies of the transitions 1481.7keV and 261.6 keV are significantly different from the values predicted by the shell model using the △ and SN parameters determined from the ^7 △ Li data.     

High-performance liquid chromatographic analysis of serum short-chain fatty acids by direct derivatization

The application of direct derivatization in conjunction with high-performance liquid chromatography is described for the analysis of short-chain fatty acids in serum. The method is based on the reaction of these acids with acidic 2-nitrophenylhydrazine hydrochloride, without complicated isolation steps, which produces their non-volatile hydrazine derivatives. The hydrazides of fourteen saturated and unsaturated, straight and branched, short-chain fatty acids were separated from other acid hydrazides and interfering components by a simple solvent extraction, and were eluted isocratically on a reversed-phase C8 column within 24 min. UV detection demonstrated that the detection limits for the acids were 200-400 fmol per injection with linearity over the range from 400 fmol to 5 nmol per injection. Analytical recoveries ranged from 96.8% to 103.1% and coefficients of variation ranged from 0.9% to 3.8%. The present method is simple, accurate and adequate for the analysis of short-chain fatty acids in biological fluids and tissues of patients suffering from organic acidemias.     

Discussion of substantially identical gel points among multiallyl monomers based on characterization of resultant network polymer precursors consisting of oligomeric primary polymer chains

No difference in the actual gel points was substantially observed among three isomeric diallyl phthalates such as diallyl phthalate (DAP), diallyl isophthalate, and diallyl terephthalate (DAT); this interesting gelation behavior was discussed further in terms of the correlation between gelation and the difference in cyclization modes, and also, the difference in reactivity between the uncyclized and cyclized radicals for cross‐linking. In the present work, we tried to extend the preceding discussion to the polymerization of triallyl trimellitate (TAT) because the molecular structure of TAT is presumed to essentially involve the characteristics of three isomeric diallyl phthalates and, therefore, the enhanced gelation was expected in TAT polymerization. However, no enhancement of gelation was observed. For a full understanding of the gelation in multiallyl cross‐linking polymerization, we explored further the polymerizations of DAP, DAT, and TAT, especially focusing on the characterization of resultant network polymer precursors (NPPs) using SEC‐MALLS‐viscometry providing the correlation of [η] versus M_w of fractionated samples. Notably, the structure of NPP consisting of oligomeric primary polymer chains generated from specific allyl polymerization would become core‐shell type dendritic with the progress of polymerization. The correlation between delayed gelation and decreased reactivity of dendritic NPP for intermolecular cross‐linking is discussed. Conclusively, the reactivity for intermolecular cross‐linking between NPPs decreased with the progress of polymerization leading to a delayed gelation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2871–2881, 2009