Matrix‐free detection of intact ions from proteins in argon‐cluster secondary ion mass spectrometry

In the secondary ion mass spectrometry (SIMS) of organic substances, the molecular weight of the intact ions currently detectable is at best only as high as 1000 Da, which for all practical purposes prevents the technique from being applied to biomaterials of higher mass. We have developed SIMS instrumentation in which the primary ions were argon cluster ions having a kinetic energy per atom, controlled down to 1 eV. On applying this instrumentation to several peptides and proteins, the signal intensity of fragment ions was decreased by a factor of 10² when the kinetic energy per atom was decreased below 5 eV; moreover, intact ions of insulin (molecular weight (MW): 5808) and cytochrome C (MW: 12 327) were detected without using any matrix. These results indicate that fragmentation can be substantially suppressed without sacrificing the sputter yield of intact ions when the kinetic energy per atom is decreased to the level of the target's dissociation energy. This principle is fully applicable to other biomolecules, and it can thus be expected to contribute to applications of SIMS to biomaterials in the future. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and biological evaluation of γ-fluoro-β,γ-unsaturated acids

Several γ-fluoro-β,γ-unsaturated acids, fluorine-containing analogues of N-acyl glycines, were synthesized via Julia-Lythgoe olefination. The antimicrobial activities of these compounds and synthetic intermediates were evaluated. Analogues with an octyl group showed in vitro antifungal activity agaist Penicillium chrysogenum IFO4626.     

Derivation of the analytical solution of Color2Gray algorithm and its application to fast color removal based on color quantization

In order to convert a color image into a monochrome one, the lightness components of pixels have to date been used as gray-levels for the representation of the monochrome image. However, saliencies of an image embedded only in the chrominance components are eliminated in such conversion. To cope with this problem, “Color2Gray” algorithm, which excels in the color removal of digital images, has been proposed by Gooch et al. [ACM Trans. Graphics 24 (2005) 634]. In this paper, the algorithm is first analyzed and its mathematical property is revealed. Then a fast Color2Gray algorithm is proposed by using the mathematical property. Finally, the validity and the effectiveness of the proposed algorithm are proven by some experiments.     

Excimer dynamics in poly(N-vinylcarbazole) films

Using a mode-locked Nd³⁺: YAG laser and a streak camera, the formation process of excimers in poly(N-vinylcarbazole) film was directly measured to be quite rapid (<100 ps). The excimer—excimer interaction in polymer film was demonstrated for the first time, and compared with the S₁-S₁ annihilation process of molecular crystals.     

Electronic states of trapped charge carriers in crystals with narrow continuum

Splitting and polarization of the charge transfer optical transitions from the 1-hydronaphthyl radical to the host molecules in naphthalene single crystal have been studied in detail and are discussed in terms of the resonance transfer integrals between host molecules.     

Anisotropic oscillator strength of 1-hydronaphthyl radical in naphthalene single crystal

The absolute value of the optical absorption strength of the 539 nm intra-radical transition of the 1-hydronaphthyl radical in a naphthalene crystal was measured with light polarized along the a, b and c′ axes. The long and short axial components of the oscillator strength were determined by using the local field tensors obtained with several methods. It was found that the local field tensors obtained recently by Munn, assuming each molecule to be two polarizable points, yield good agreement between the molecular axial components of the oscillator strengths obtained experimentally and theoretically. The local field tensors obtained previously with the single point-dipole approximation were found to result in inconsistency.     

Electric conductivities of 1:1 electrolytes in liquid methanol along the liquid-vapor coexistence curve up to the critical temperature. II. KBr and KI solutions

The molar conductivities Lambda of KBr and KI in dilute methanol solutions were measured along the liquid-vapor coexistence curve up to the critical temperature (240 degrees C). The concentration dependence of Lambda in each condition was analyzed by the Fuoss-Chen-Justice equation to obtain the limiting molar conductivities and the molar association constants. Using the present data together with the literature ones, the validity of the Hubbard-Onsager (HO) dielectric friction theory based on the sphere-in-continuum model was examined for the translational friction coefficients zeta of the halide ions (the Cl(-), Br(-), and I(-) ions) in methanol in the density range of 2.989rho(c)> or =rho> or =1.506rho(c), where rho(c)=0.2756 g cm(-3) is the critical density of methanol. For all the halide ions studied, the friction coefficient decreased with decreasing density at rho>2.0rho(c), while the nonviscous contribution Deltazeta/zeta increased; Deltazeta was defined as the difference between zeta and the friction coefficient estimated by the Stokes law. The density dependence of zeta and Deltazeta/zeta were well reproduced by the HO theory at rho>2.0rho(c). The HO theory also explained the ion-size dependence of Deltazeta/zeta which decreased with ion-size at rho>2.0rho(c). At rho<2.0rho(c), on the other hand, the HO theory could not explain the density and the ion-size dependences of zeta and Deltazeta/zeta. These results indicated that the application limit of the HO theory lied about rho=2.0rho(c) which is the same as the application limit observed for the alkali metal ions. The present results were also compared with the results in subcritical aqueous solutions.     

Metal adsorbent for alkaline etching aqua solutions of Si wafer

High performance adsorbent is expected to be synthesized for the removal of Ni and Cu ions from strong alkaline solution used in the surface etching process of Si wafer. Fibrous adsorbent was synthesized by radiation-induce emulsion graft polymerization onto polyethylene nonwoven fabric and subsequent amination. The reaction condition was optimized using 30 L reaction vessel and nonwoven fabric, 0.3 m width and 18 m long. The resulting fibrous adsorbent was evaluated by 48 wt% NaOH and KOH contaminated with Ni and Cu ions, respectively. The concentration levels of Ni and Cu ions was reduced to less than 1 μg/kg (ppb) at the flow rate of 10 h^?1 in space velocity. The life of adsorbent was 30 times higher than that of the commercialized resin. This novel adsorbent was commercialized as METOLATE^® since the ability of adsorption is remarkably higher than that of commercial resin used practically in Si wafer processing.     

Organized metamaterials comprised of gold nanoneedles in a lattice generated on silicon (100) wafer substrates by interfering femtosecond laser processing

In this paper,we fabricate a lateral phase change memory device composed of a Ge₂Sb₂Te₅ nanowire (GST NW) fully confined in a tungsten electrode nanogap. A SiNx spacer is used not only as etch mask for the fabrication of the GST NW, but also as sacrificial layer for the lift-off process, which makes it feasible to fully confine the GST NW in the metal electrode nanogap. Electrical characterization shows that the device has unprecedentedly low threshold current and SET voltage of only 16 μA and 80 mV, respectively.     

Spectroscopic measurement of glucose content in a solution involving the water molecule clusters downsized by ultrasonic cavitations

In near-infrared spectroscopy, the detection of low glucose condensation around 100 mg/dl is extremely difficult owing to various hydrogen-bonded water clusters. Ultrasonic cavitations were effective to downsize them or reconstruct them. It was found that glucose solution attacked by cavitations had a peculiar recovery time depending on the glucose condensation until its chemical reaction approached the equilibrium. The absorbance profiles of such varying solutions manifested that their variations depended on the glucose content and the PLS regression method for them enabled estimating the glucose condensation with an accuracy of ±16 mg/dl.