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71.
Codebook-based single-microphone noise suppressors, which exploit prior knowledge about speech and noise statistics, provide better performance in nonstationary noise. However, as the enhancement involves a joint optimization over speech and noise codebooks, this results in high computational complexity. A codebook-based method is proposed that uses a reference signal observed by a bone-conduction microphone, and a mapping between air- and bone-conduction codebook entries generated during an offline training phase. A smaller subset of air-conducted speech codebook entries that accurately models the clean speech signal is selected using this reference signal. Experiments support the expected improvement in performance at low computational complexity. 相似文献
72.
Kamaraj Balamurugan Aaramadaka Sunil Kumar Reddy Dharmarajan Sriram 《Tetrahedron letters》2009,50(45):6191-353
A series of novel 2-amino-5-arylthieno[2,3-b]thiophenes has been synthesized regioselectively from the reaction of 5-aryldihydro-3(2H)-thiophenones with ethyl cyanoacetate/malononitrile and sulfur powder in the presence of morpholine under thermal as well as microwave irradiation conditions. This transformation presumably occurs via domino Gewald reaction-dehydrogenation sequence. The 2-amino-5-arylthieno[2,3-b]thiophenes were evaluated for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug resistant M. tuberculosis (MDR-TB). Among 12 compounds screened, ethyl 2-amino-5-(1-naphthyl)thieno[2,3-b]thiophene-3-carboxylate was found to be the most active compound with MIC of 1.1 μM against MTB and MDR-TB. 相似文献
73.
Dr. Sinan Wang Dr. David E. Korenchan Paola M. Perez Dr. Céline Taglang Dr. Thomas R. Hayes Dr. Renuka Sriram Dr. Robert Bok Andrew S. Hong Yunkou Wu Henry Li Prof. Zhen Wang Prof. John Kurhanewicz Prof. David M. Wilson Prof. Robert R. Flavell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11842-11846
Alterations in Zn2+ concentration are seen in normal tissues and in disease states, and for this reason imaging of Zn2+ is an area of active investigation. Herein, enriched [1-13C]cysteine and [1-13C2]iminodiacetic acid were developed as Zn2+-specific imaging probes using hyperpolarized 13C magnetic resonance spectroscopy. [1-13C]cysteine was used to accurately quantify Zn2+ in complex biological mixtures. These sensors can be employed to detect Zn2+ via imaging mechanisms including changes in 13C chemical shift, resonance linewidth, or T1. 相似文献
74.
TiO2 nanoparticles have been prepared by simple chemical precipitation method and annealed at different temperatures. The as-prepared TiO2 are amorphous, and they transform into anatase phase on annealing at 450 °C, and rutile phase on annealing at 900 °C. The X-ray diffraction results showed that TiO2 nanoparticles with grain size in the range of 21–24 nm for anatase phase and 69–74 nm for rutile phase have been obtained. FESEM images show the formation of TiO2 nanoparticles with small size in structure. The FTIR and Raman spectra exhibited peaks corresponding to the anatase and rutile structure phases of TiO2. Optical absorption studies reveal that the absorption edge shifts towards longer wavelength (red shift) with increase of annealing temperature. 相似文献
75.
76.
A new approach to Heisenberg ferromagnet using the spin coherent state representation is developed. The differential operator representation of spin angular momentum operators is used to derive thec-number analogs of the basic quantum mechanical equations, viz., the Schrödinger, Bloch and Liouville equations for the Heisenberg ferromagnet. As an important illustration of our formulation, which has noad hoc assumptions and does not use any boson representation, the excitation spectrum for one, two and three spin waves is obtained. In these cases it is also shown that eigenvalue spectrum can be obtained by completely ignoring the kinematical interactions. 相似文献
77.
A whole-field projection-speckle technique to measure out of plane displacements of initially flat structures has been presented. The method is based on digital correlation of images obtained from a TV camera. An improved digital-correlation function has been derived and described along with the analysis scheme. An instrumentation system based on a desktop computer has been set up to implement the method. Experimental results from simple static tests have been used to validate the technique. 相似文献
78.
Nonlinear effective Lagrangian models with a chiral symmetry have been used to describe strong interactions at low energy,
for a long time. The Skyrme model and the chiral quark-meson model are two such models, which have soliton solutions which
can be identified with the baryons. We describe the various kinds of soliton states in these nonlinear models and discuss
their physical significance and uses in this review. We also study these models from the view point of classical nonlinar
dynamical systems. We consider fluctuations around theB=1 soliton solutions of these models (B, being the baryon number) and solve the spherically symmetric, time-dependent systems. Numerical studies indicate that the
phase space around the Skyrme soliton solution exhibits spatio-temporal chaos. It is remarkable that topological solitons
signifying stability/order and spatio-temporal chaos coexist in this model. In contrast with this, the soliton of the quark-meson
model is stable even for large perturbations. 相似文献
79.
One-electron oxidation of duplex DNA generates a radical cation that migrates through the nucleobases until it is trapped by an irreversible reaction with water or oxygen. The trapping site is often a GG step, because this site has a relatively low ionization potential and this causes the radical cation to pause there momentarily. Modifications to guanine that lower its ionization potential convert it to a better trap for the radical cation. One such modification is the formation of the Watson-Crick base pair with cytosine, which is reported to very significantly decrease its ionization potential. Methylation of cytosine to form 5-methylcytosine (5-MeC) is a naturally occurring reaction in genomic DNA that may be associated with regions of enhanced oxidative damage. The G.5-MeC base pair is reported to be more rapidly oxidized than normal G.C base pairs. We examined the oxidation of DNA oligomers that were substituted in part with 5-MeC. Irradiation of a covalently linked anthraquinone group injects a radical cation into the DNA and results in strand cleavage after piperidine treatment. For the sequences examined, substitution of 5-MeC for C has no measurable effect on the reactions. Cytosine methylation is not a general cause of enhanced oxidative damage in DNA. 相似文献
80.
Combinatorial synthesis of anti-HIV agents--a review 总被引:1,自引:0,他引:1