Metabolic profiling using Fourier-transform ion-cyclotron-resonance mass spectrometry

With the aid of the extreme resolving power of Fourier-transform ion-cyclotron-resonance mass spectrometry (FT-ICR/MS), we have developed a metabolomics platform for high-throughput metabolic profiling and metabolite candidate identification integrating a data-processing system, the Dr.DMASS program (), and a metabolite-species database, KNApSAcK (). We discuss the potential of this FT-ICR/MS-based metabolic profiling scheme as a general metabolomics tool by clarification of plant metabolic disorders and specific metabolite accumulation patterns caused by herbicidal enzyme inhibitors.     

Intensity and frequency noise characteristics of two coherently-added injection-locked Nd:YAG lasers

Coherent addition of two injection-locked Nd:YAG lasers has been performed. A maximum output power of 4.4 W and addition efficiency of 0.94 was achieved, which is the highest power-coupling efficiency ever reported. It was shown experimentally that the frequency and intensity noise level of the coherently-added laser are the same as those of a single injection-locked laser. In particular, no additional intensity noise was observed above the relaxation oscillation frequency of the slave laser, which is suitable for use as the light source for a future gravitational wave detector. The frequency noise of the coherently-added laser was suppressed to 1×10^-4 Hz/ by controlling that of the master laser, and the intensity noise was also suppressed to 1×10^-8 / by controlling the intensity of pump lasers used for the slave lasers. Received: 11 April 2001 / Revised version: 20 June 2001 / Published online: 19 September 2001     

Ferrocene-Containing Pseudorotaxanes in Crystals: Aromatic Interactions with Hammett Correlation

Single crystals of pseudorotaxanes, [(FcCH₂NH₂CH₂Ar)(DB24C8)][PF₆] (DB24C8 = dibenzo[24]crown-8, Fc = Fe(C₅H₄)(C₅H₅), Ar = -C₆H₃-3,4-Cl₂, -C₆H₃-3,4-F₂, -C₆H₄-4-F, -C₆H₄-4-Cl, -C₆H₄-4-Br, -C₆H₃-3-F-4-Me, -C₆H₄-4-I) and [(FcCH₂NH₂CH₂C₆H₄-4-Me)(DB24C8)][Ni(dmit)₂] (dmit = 1,3-dithiole-2,4,5-dithiolate), were obtained from solutions containing DB24C8 and ferrocenylmethyl(arylmethyl)ammonium. X-ray crystallographic analyses of the pseudorotaxanes revealed that the aryl ring of the axle moiety and the catechol ring of the macrocyclic component were at close centroid distances and parallel or tilted orientation. The structures with parallel aromatic rings showed correlation of the distances between the centroids to Hammett substituent constants of the aryl groups.     

Excitation wavelength dependence and magnetic field effect on aerosol particle formation from a gaseous mixture of carbon disulphide and glyoxal

Upon excitation of carbon disulphide (CS₂) molecules under UV light irradiation at 313?nm a gaseous mixture of CS₂ and glyoxal deposited sedimentary aerosol particles only. The nucleation process of the aerosol particles was investigated by measuring the He–Ne laser light intensity scattered by the aerosol particles formed under light irradiation at 313?nm, and the chemical structure of the sedimentary particles was analysed by measuring the FT-IR and X-ray photoelectron spectra. On application of a magnetic field of up to 5?T, the nucleation process was decelerated and the chemical species originating from CS₂ were less abundant. The results were compared with those obtained under visible light irradiation at 435.8?nm reported previously. Chemical reactions between CS₂ and glyoxal molecules, which were responsive to the magnetic field, are discussed briefly.     

Large deviations of realized volatility

This paper studies large and moderate deviation properties of a realized volatility statistic of high frequency financial data. We establish a large deviation principle for the realized volatility when the number of high frequency observations in a fixed time interval increases to infinity. Our large deviation result can be used to evaluate tail probabilities of the realized volatility. We also derive a moderate deviation rate function for a standardized realized volatility statistic. The moderate deviation result is useful for assessing the validity of normal approximations based on the central limit theorem. In particular, it clarifies that there exists a trade-off between the accuracy of the normal approximations and the path regularity of an underlying volatility process. Our large and moderate deviation results complement the existing asymptotic theory on high frequency data. In addition, the paper contributes to the literature of large deviation theory in that the theory is extended to a high frequency data environment.     

Highly efficient photoelectrochemical water splitting using a thin film photoanode of BiVO4/SnO2/WO3 multi-composite in a carbonate electrolyte

The solar energy conversion efficiency considering the energy loss by the external bias for water splitting reached ca. 0.9 or 1.35% using single- or double-stacked photoanodes, respectively, of BiVO(4)/SnO(2)/WO(3) multilayers in a highly concentrated carbonate electrolyte aqueous solution.     

Crystal structure of stable protein CutA1 from psychrotrophic bacterium Shewanella sp. SIB1

CutA1 is widely found in bacteria, plants and animals, including humans. The functions of CutA1, however, have not been well clarified. It is known that CutA1s from Pyrococcus horikoshii, Thermus thermophilus and Oryza sativa unfold at temperatures remarkably higher than the growth temperatures of the host organisms. In this work the crystal structure of CutA1 from the psychrotrophic bacterium Shewanella sp. SIB1 (SIB1-CutA1) in a trimeric form was determined at 2.7?? resolution. This is the first crystal structure of a psychrotrophic CutA1. The overall structure of SIB1-CutA1 is similar to those of CutA1 from Homo sapiens, Escherichia coli, Pyrococcus horikoshii, Thermus thermophilus, Termotoga maritima, Oryza sativa and Rattus norvergicus. A peculiarity is observed in the β2 strand. The β2 strand is divided into two short β strands, β2a and β2b, in SIB1-CutA1. A thermal denaturation experiment revealed that SIB1-CutA1 does not unfold completely at 363?K at pH 7.0, although Shewanella sp. SIB1 cannot grow at temperatures exceeding 303?K. These results indicate that the trimeric structural motif of CutA1 is the critical factor in its unusually high stability and suggest that CutA1 needs to maintain its high stability in order to function, even in psychrotrophs.     

Relaxation of shish‐kebab precursor in isotactic polystyrene after short‐term shear flow

We studied the formation and relaxation of precursors of shish‐kebab in isotactic polystyrene after applying pulse shear flow at temperatures above the nominal melting temperatures T_m (=223 °C). It was found that the string‐like objects that were assigned to precursors in a previous article appeared in micrometer scale up to ～285 °C, which was very close to the equilibrium melting temperature T (=289 °C), and the length and the diameter showed two‐step decays consisting of the fast and slow (almost nondecaying) components below ～270 °C, whereas the slow component disappeared above ～270 °C, suggesting that some mechanism stabilizing the string‐like objects disappeared at ～270 °C. It was also found that the two‐step decay was a nature of a single string‐like object, but not an average nature of many precursors, showing heterogeneous inner structure of the precursor. We discussed a possibility that the string‐like object had a fringed micelle type structure including large crystals with a melting temperature of ～270 °C. Within the proposed picture, the highest temperature for the precursor formation (～285 °C) was explained as a melting of the large crystals in oriented melt. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Selective detection of minor isotope lines in saturated absorption spectra by absorption filtering of major isotope lines

We demonstrate a simple method that can be used to detect minor isotope lines in a saturated absorption spectrum by the absorption filtering of major isotope lines. We investigate this method for use in the spectroscopy of the ¹S₀-¹P₁ transition in Yb at 399 nm by controlling the density of Yb atoms by varying the discharge current of a hollow cathode lamp. The performance of an extended-cavity laser diode using a high-power ultraviolet diode chip is also analyzed.