Functional mapping of carious enamel in human teeth with Raman microspectroscopy

We employed Raman microspectroscopy to measure the Raman spectra of phosphate in sound and carious tooth substance. The peak intensity at 960 cm⁻¹ of the phosphate (PO₄³⁻) symmetric stretching vibrational mode (υ₁) in sound enamel was stronger than that of sound dentin, which indicated that sound enamel contained more phosphate than sound dentin. Furthermore, the element analysis of phosphate in sound teeth substance, measured using a scanning electron microscope (SEM) equipped with an energy dispersive X‐ray spectroscope (EDX), gave similar results to those of the Raman measurement. In addition, the border between sound enamel and dentin was clearly demonstrated by mapping the image of the Raman spectrum of phosphate. The mapping image of phosphate in the carious enamel region revealed a heterogeneous low Raman spectrum intensity of phosphate in the area surrounding carious enamel; this finding indicates that phosphate had dissolved from the tooth substance in such areas. In contrast with the decrease in the Raman spectrum intensity of phosphate, the intensity of amide I increased mainly in the low‐phosphate area. Although it remains very difficult to clinically identify the accurate border between sound and carious tooth substance, this distinction may be enabled by using the Raman spectrum of carious tooth substance. Copyright © 2008 John Wiley & Sons, Ltd.     

Substrate dependence of ion motion in femtosecond laser ablation cloud observed by planar laser-induced fluorescence

We have observed the motion of Sm⁺ ions as well as Sm atoms produced by femtosecond laser ablation of a solidified samarium solution sample on substrates by using a planar laser-induced fluorescence method. Kinetic energies of both Sm⁺ ions and Sm atoms increase as the electrical conductivity of the substrate decreases, which suggests the effect of surface charging. The kinetic energy of Sm⁺ ions is larger than that of Sm atoms for a variety of substrates due to the further electrical acceleration by the surface charge. The knowledge of ion motion will be the key information for the optimization of femtosecond laser simultaneous atomization and ionization of organic and inorganic samples on substrates.     

Rotational anisotropy in second harmonic intensity from Cu nanowire arrays on the NaCl (1 1 0) substrates

We have measured the azimuthal angle dependence of the second harmonic (SH) intensity from Cu nanowires on the faceted NaCl (1 1 0) substrates in air at the fundamental photon energy of 1.17 eV. The SH intensity patterns showed two main lobes for p-in/p-out, s-in/p-out, and s-in/s-out polarization configurations. From the results of the experiment and the pattern analysis we have found that the observed SH light is enhanced by the electric field components along the substrate normal.     

Development of novel MgCl2 supported catalyst with trivalent titanocene complex of CP2TiCl2AlCl2 for propylene polymerization

Three kinds of MgCl₂‐supported trivalent titanocene catalyst (Cat. 1: Cp₂TiCl₂AlCl₂/MgCl₂, Cat. 2: CpCp*TiCl/MgCl₂, Cat. 3: Cp₂TiCl/MgCl₂) were prepared and tested for propylene polymerization. It was found that Cat. 1, combined with ordinary alkylaluminum as cocatalyst, produced PP containing 31.8 wt % of isotactic PP in fairly good yield. On the other hand, Cats. 2 and 3 hardly showed any activity. The effects of diisopropyldimethoxysilane (DIPDMS) on isospecificity of the Cat. 1 also were investigated. The isotactic index (I.I.) of PP was improved drastically by the addition of DIPDMS as external donor and reached the value as high as 98.4%, even in the absence of any internal donors. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3355–3359, 2000     

New simplified coupling scheme for the delivery of 20 MW Nd:YAG laser pulses by large core optical fibers

The feasibility of transmitting 20 MW, 5 ns laser pulses from a frequency doubled Nd:YAG laser through a standard 1500 μm multi mode optical fiber is demonstrated. A new coupling scheme employing an optical homogenizer prevents breakdown in air without the use of a vacuum chamber. At the same time a very homogeneous flat top beam profile on the fiber surface is achieved. The new scheme therefore clearly simplifies fiber coupling of high power laser pulses. Experiments on the delivery of more than 20000 pulses with 110 mJ mean energy without fiber damage have been performed. Received: 2 August 2000 / Revised version: 18 August 2000 / Published online: 22 November 2000     

Fluorometric determination of cyanide with 2,3-naphthalenedialdehyde and taurine

A method is proposed for the fluorometric determination of cyanide based on a fluorogenic reaction with 2,3-naphthalenedialdehyde and taurine at basic pH. As little as 10 pmole of cyanide in 500 mul of sample can be determined.     

Accurate and efficient determination of boron content in volcanic rocks by neutron induced prompt gamma-ray analysis

An accurate and efficient analytical method using neutron-induced prompt γ-ray was developed for the determination of boron contents in volcanic rocks. We corrected the effect of sample geometry and flux fluctuation by using silicon as an internal standard. However, we found that the slopes of the calibration line vary among volcanic samples with different matrix. Because the increase of boron activity correlates positively with γ-ray count rate of hydrogen (water), we call this as the hydrogen effect. The hydrogen effect was confirmed by our experiment in which the boron activities showed systematic increase with the amount of added hydrogen (water). Most volcanic rocks, however, contain little water (<2 wt.%) to show this effect. We determined boron contents in various volcanic rocks in order to confirm the validity of the procedure that we established. The analyzed boron contents agreed well with the previous reported values. For efficient PGA of boron in volcanic rocks, we recommend JB-2 (GSJ standard rock) as a single geochemical standard, because of its high boron content (31.2 ppm).     

Promotion of crystal growth rate in aqueous solution by direct contact with gas corona discharge

A new technique to promote crystal growth in aqueous solution using gas plasma is proposed. In this method, short‐lived radical species produced in solution which is contacted with gas corona discharge play a role to increase chemical potential of inorganic solute. In an experimental examination, single crystal of KDP was grown in a supersaturated solution which receives oxygen ions and radicals from adjacent corona discharge in air. KDP crystal has two unique growth faces (100) and (101), and the growth rates of both faces were increased considerably by generating the corona discharge. The both growth rates with and without corona discharge were well converged by one function based on chemical potential supersaturation. This result revealed that the solution in contact with gas corona discharge has a larger capacity of chemical potential than that without the discharge. Short‐lived species induced by gas corona discharge are considered to be anti‐solvents to cause this effect. The crystal growth process proposed here is considered to be an excellent method in terms of low impurity inclusion because such short‐lived species do not remain in the final crystal products and solution. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Alternating copolymerization of ethylene and propene with the [ethylene(1-indenyl)(9-fluorenyl)]zirconium dichloridemethylaluminoxane catalyst system

The copolymerization of ethylene and propene was conducted at −40°C with the [ethylene(1-indenyl)(9-fluorenyl)]zirconium dichloride-methylaluminoxane catalyst system, and the microstructure of the resulting copolymers was analyzed in detail by ¹³C NMR. The content of alternating [EP] sequences increased markedly with an increase in the feed ratio of propene to ethylene. A poly(ethylene-co-propene) with a proportion of [EP] sequences over 95% was thus obtained under appropriate copolymerization conditions. It was also demonstrated that the alternating ethylene-propene copolymer is stereoregular and isotactic.