Real-time processing using the frequency domain binaural model

There are many approaches to achieving high-performance speech enhancement. The modeling of the human auditory system is a good approach, since human beings can focus on target speech under concurrent speech conditions. One example of the binaural models is the time domain binaural model. However, this model has a high-calculation cost because the algorithm is based on auto-correlation, which is computationally intensive. Another example is the frequency domain binaural model proposed by Nakashima et al. [Nakashima H, Chisaki Y, Usagawa T, Ebata M. Frequency domain binaural model based on interaural phase and level differences. Acoust Sci Technol 2003;24(4):172-8]. Since the frequency domain binaural model uses the fast fourier transform, the calculation cost is much lower than that of the time domain binaural model. Therefore, it is not difficult to perform real-time processing using recent hardware such as digital signal processors and even laptop personal computers. However the quality of the segregated sound obtained using the frequency domain binaural model depends on system parameters such as frequency resolution and frame shift length for overlap adding in time domain. This paper introduces the construction of a prototype of a hearing assistant system based on the frequency domain binaural model. The detailed implementation techniques and parameter tuning are mentioned. The proposed system runs in real-time after parameter tuning. The directional attenuation levels, that is, the directivity patterns of the proposed system is measured. Finally, it is shown that the prototype can extract sounds coming from specific directions in real-time.     

Acid anhydrides as alternatives to acid chlorides in the palladium‐catalyzed reaction with silacyclobutanes

The palladium‐catalyzed reaction of acid anhydrides with silacyclobutane gives a mixture of cyclic silyl enol ether, carboxy(propyl)silane, and 3‐(carboxysilyl)ketone. In the presence of N,N‐dicyclohexylcarbodiimido (DCC), the reaction preferentially provides a cyclic silyl enol ether in a good yield. In addition, the palladium‐catalyzed reaction of benzoic acid with silacyclobutane in the presence of two equivalents of DCC also affords a cyclic silyl enol ether in a moderate yield. Copyright © 2001 John Wiley & Sons, Ltd.     

纤维素基水处理剂研究进展

根据纤维素基水处理剂的结构特点对其进行了分类和划分,从载体形态、接枝链与载体接枝方法、功能吸附/脱附基团选取及功能化方法、吸附/脱附性能的影响因素和脱附方法等五个方面综述了国内外在该领域的研究现状;并对其发展前景进行了展望.     

Axonal outgrowth is associated with increased ERK 1/2 activation but decreased caspase 3 linked cell death in Schwann cells after immediate nerve repair in rats

Background  

Extracellular-signal regulated kinase (ERK1/2) is activated by nerve damage and its activation precedes survival and proliferation of Schwann cells. In contrast, activation of caspase 3, a cysteine protease, is considered as a marker for apoptosis in Schwann cells. In the present study, axonal outgrowth, activation of ERK1/2 by phosphorylation (p-ERK 1/2) and immunoreactivity of cleaved caspase 3 were examined after immediate, delayed, or no repair of transected rat sciatic nerves.     

The role of spin-orbit potential in nuclear prolate-shape dominance

It is confirmed, in terms of the Woods-Saxon-Strutinsky method, that the spin-orbit potential plays a decisive role in the predominance of prolate deformation, which has been a long standing problem in nuclear physics. It is originated from the combined effects of the spin-orbit coupling and the diffused surface of the potential, in agreement with the previous work based on a more schematic Nilsson-Strutinsky method. The degree of prolate-shape dominance exhibits an oscillatory behavior with respect to the strength of spin-orbit potential and, the prolate-shape dominance is realized at the proper strength of the spin-orbit potential together with the standard surface diffuseness; this oscillatory behavior disappears in case of small diffuseness corresponding to ellipsoidal cavity. The calculated energy differences between oblate and prolate minima in this Letter are consistent with those of our extensive self-consistent calculations of the Hartree-Fock + BCS method with the Skyrme interaction.     

Vibronic Structures in Absorption and Fluorescence Spectra of Firefly Oxyluciferin in Aqueous Solutions

To elucidate the factors determining the spectral shapes and widths of the absorption and fluorescence spectra for keto and enol oxyluciferin and their conjugate bases in aqueous solutions, the intensities of vibronic transitions between their ground and first electronic excited states were calculated for the first time via estimation of the vibrational Franck–Condon factors. The major normal modes, overtones and combination tones in absorption and fluorescence spectra are similar for all species. The theoretical full widths at half maximum of absorption spectra are 0.4–0.7 eV and those for the fluorescence spectra are 0.4–0.5 eV, except for phenolate‐keto that exhibits exceptionally sharp peak widths due to the dominance of the 0–0′ or 0′–0 band. These spectral shapes and widths explain many relevant features of the experimentally observed spectra.     

Ruthenium‐Immobilized Periodic Mesoporous Organosilica: Synthesis,Characterization, and Catalytic Application for Selective Oxidation of Alkanes

Periodic mesoporous organosilica (PMO) is a unique material that has a crystal‐like wall structure with coordination sites for metal complexes. A Ru complex, [RuCl₂(CO)₃]₂, is successfully immobilized onto 2,2’‐bipyridine (BPy) units of PMO to form a single‐site catalyst, which has been confirmed by various physicochemical analyses. Using NaClO as an oxidant, the Ru‐immobilized PMO oxidizes the tertiary C?H bonds of adamantane to the corresponding alcohols at 57 times faster than the secondary C?H bonds, thereby exhibiting remarkably high regioselectivity. Moreover, the catalyst converts cis‐decalin to cis‐9‐decalol in a 63 % yield with complete retention of the substrate stereochemistry. The Ru catalyst can be separated by simple filtration and reused without loss of the original activity and selectivity for the oxidation reactions.     

Ultrafast spectroscopy and coherent acoustic phonons of Au-Ag core-shell nanorods

We performed the first investigations of coherent acoustic phonons in Au-Ag core-shell nanorods, which were compared with the results of parental Au nanorods. Both breathing and extensional modes were observed in Au-Ag core-shell nanorods with ~11 nm Ag shell while only extensional modes were detected in other core-shell nanorods with 4-7 nm Ag shell. Young's modulus estimated from the oscillation period of extensional modes was found to be larger for Au-Ag core-shell nanorods with ~4 nm Ag shell, as compared with that of Au nanorods. The value of Young's modulus decreases with the increase of the Ag shell thickness and finally becomes smaller than that of Au nanorods. This phenomenon is interpreted in terms of the surface effects and the existence of grain boundaries in the lattice structure of Ag shell.