Continuous-time image reconstruction for binary tomography

Binary tomography is the process of reconstructing a binary image from a finite number of projections. We present a novel method for solving binary tomographic inverse problems using a continuous-time image reconstruction (CIR) system described by nonlinear differential equations based on the minimization of a double Kullback–Leibler divergence. We prove theoretically that the divergence measure monotonically decreases in time. Moreover, we demonstrate numerically that the quality of the reconstructed images of the nonlinear CIR system is better than those from an iterative reconstruction method.     

Equality conditions for lower bounds on the smallest singular value of a bidiagonal matrix

Several lower bounds have been proposed for the smallest singular value of a square matrix, such as Johnson’s bound, Brauer-type bound, Li’s bound and Ostrowski-type bound. In this paper, we focus on a bidiagonal matrix and investigate the equality conditions for these bounds. We show that the former three bounds give strict lower bounds if all the bidiagonal elements are non-zero. For the Ostrowski-type bound, we present an easily verifiable necessary and sufficient condition for the equality to hold.     

Control of oscillating combustion and noise based on local flame structure

To control combustion oscillations, the characteristics of an oscillating swirl injection premixed flame have been investigated, and control of oscillating combustion and noise based on local flame structure has been conducted. The r.m.s. value of pressure fluctuations and noise level show significantly large values between = 0.8 and 1.1. The beating of pressure fluctuations is observed for the large oscillating flame conditions in this combustor. Relationship between beating of pressure fluctuations and local flame structure was observed by the simultaneous measurement of CH/OH planar laser induced fluorescence and pressure fluctuations. The local flame structure and beating of pressure fluctuations are related and the most complicated flame is formed in the middle pressure fluctuating region of beating. The beating of pressure fluctuations, which plays important roles in noise generation and nitric oxide emission in this combustor, could be controlled by injecting secondary fuel into the recirculating region of oscillating flames. Injecting secondary fuel prevented lean blowout, and low NO_x combustion was also achieved even for the case of pure methane injection as a secondary fuel. By injecting secondary fuel into the recirculating region near the swirl injector, the flame lifted from the swirl injector and its reaction region became uniform and widespread, hence resulting in low nitric oxide emission. Secondary mixture injection, fuel diluted with air, is not effective for control of combustion oscillations suppression and lean blowout prevention.     

Extended Hypervalent 5c–6e Interactions: Linear Alignment of Five C─Z- - -O- - -Z─C (Z = S,Se) Atoms in Anthraquinone and Anthracene Systems

Abstract

Structures of 1,8-(ArZ)₂C₁₄H₆O₂ and 9-(MeO)-1,8-(ArZ)₂C₁₄H₇ (Z = S, Se) are determined by X-ray crystallographic analysis. Five C─Z- - -O- - -Z─C atoms of the compounds align linearly, which are analyzed by the extended hypervalent 5c–6e model, based on QC calculations. CT of the 5c–6e occurs as the σ^*(C─Z) ← n _p (O)→ σ*(Z─C) direction.     

Synthesis and properties of fullerene (C70) complexes of 2,6-bis(porphyrin)-substituted pyrazine derivatives bound to a Pd(II) ion

2,6-Bis(porphyrin)-substituted 3,5-dimethylpyrazine and its zinc complex bound C₇₀ to yield 1:1 inclusion complexes, which were characterised by ESI-MS, UV–vis, fluorescence and NMR spectroscopies. Association constants of the C₇₀ complexes were determined by fluorescence and NMR spectral analyses. A decrease in absorbance of the Soret band of the pyrazine derivative by the effect of C₇₀ was observed, suggesting the existence of a charge transfer interaction between C₇₀ and porphyrin. Experimentally reliable values for the association constants were obtained by the NMR method and were about six times larger than those of the corresponding C₆₀ complexes. Palladium complexation of the porphyrin–pyrazine ligand was found to enhance the association with fullerene. The association constant of 2,6-bis(porphyrin-Zn)-substituted 3,5-dimethylpyrazine-Pd(II) complex with C₇₀ was determined to be 8400 ± 900 M^? 1. From the comparison of the association constants, it was found that inclusion room for C₇₀ in the Pd(II) complex was maintained, juxtaposed between porphyrins attached to the opposite sides of the pyrazine ligands.

     

An improved sample preparation method for the sensitive detection of peptides by MALDI‐MS

We describe here an optimization study of the sample preparation conditions for sensitive detection of peptides by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS). Among many factors in the conditions, we varied the percent acetonitrile in the peptide solution, the percent acetonitrile in the matrix solution and the α‐cyano‐4‐hydroxycinnamic acid (CHCA) concentration in the matrix solution. CHCA was chosen because it is the most frequently used matrix for analyzing peptides. The well‐established dried‐droplet method was employed for sample deposition. The examined range of the concentration of CHCA was from 0.01 to 10 mg/ml, and the MeCN content of the solvent for matrix/analyte was 10% to 50%. The indicator for the detection sensitivity was the S/N ratio of the peaks of peptides used. Highly increased sensitivity (100‐ to 1000‐fold) was observed for the optimal CHCA concentration of 0.1 mg/ml in 20% MeCN/0.1% aq. trifluoroacetic acid (TFA), as compared with the conventional concentration (10 mg/ml) in 50% MeCN/0.1% aq. TFA. For example, the limit of detection of human ACTH 18–39 was 10 amol/well for the optimal condition but 10 fmol/well for the conventional condition. The optimal condition (0.1 mg/ml CHCA in 20% MeCN/0.1% aq. TFA) was verified with five model peptides and provided significant improvement in sensitivity (by two to three orders of magnitude) compared with the conventional conditions. Optimizing the CHCA concentration and solvent composition significantly improved the detection sensitivity in the analysis of peptides by MALDI‐MS. Copyright © 2013 John Wiley & Sons, Ltd.     

Optimized LiVOPO4 for cathodes in Li-ion rechargeable batteries

Improvement of the rate properties of orthorhombic LiVOPO₄ by using a milling approach and acetylene black additives as electronic binder is investigated. The average particle size of orthorhombic LiVOPO₄ was reduced from 12.0 μm to 6.1 μm by milling process by which the Li intercalation capacity into LiVOPO₄ increased to 40 mAhg⁻¹ at 0.4 mAcm⁻² (C/5). At an optimized acetylene black amount of 15 wt.%, a better uniformity in particle size distribution and dispersion of the current distribution was obtained. Thus, enhancing the kinetic performance a fairly large reversible intercalation capacity of Li was achieved with values of 100 and 60 mAhg⁻¹ at high rate conditions of C/5 (0.4 mAcm⁻²) and 1C (2 mAcm⁻²), respectively. Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 – 8, 2005.