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881.
Fuchs GD Dobrovitski VV Hanson R Batra A Weis CD Schenkel T Awschalom DD 《Physical review letters》2008,101(11):117601
We use single-spin resonant spectroscopy to study the spin structure in the orbital excited state of a diamond nitrogen-vacancy (N-V) center at room temperature. The data show that the excited-state spin levels have a zero-field splitting that is approximately half of the value of the ground state levels, a g factor similar to the ground state value, and a hyperfine splitting approximately 20x larger than in the ground state. In addition, the width of the resonances reflects the electronic lifetime in the excited state. We also show that the spin level splitting can significantly differ between N-V centers, likely due to the effects of local strain, which provides a pathway to control over the spin Hamiltonian and may be useful for quantum-information processing. 相似文献
882.
Competitive FRET-Aptamer-Based Detection of Methylphosphonic Acid,a Common Nerve Agent Metabolite 总被引:1,自引:1,他引:0
Competitive fluorescence resonance energy transfer (FRET)-aptamer-based assay formats are described for one-step detection
of methylphosphonic acid (MPA; a metabolite of several organophosphorus (OP) nerve agents). AminoMPA was attached to tosyl-magnetic
beads and used for DNA aptamer selection from which one dominant aptamer sequence emerged. Two different FRET approaches were
attempted. In one approach, the complementary DNA sequence was used as a template for labeling the aptamer with Alexa Fluor
546 (AF 546)-14-dUTP by asymmetric PCR. Following 3-dimensional (3-D), molecular modeling of the aptamer-MPA complex, a series
of three fluoresceinated aptamers labeled at positions 50, 51, and 52 in the putative optimal binding pocket were synthesized.
In both FRET formats, aminoMPA was linked to Black Hole Quencher (BHQ-1 or BHQ-2)-succinimides and allowed to bind the fluorescein
or AF 546-labeled MPA aptamer. Following gel filtration to purify the labeled MPA aptamer-BHQ-aminoMPA FRET complexes, the
complexes were competed against various concentrations of unlabeled MPA, MPA derivatives, and unrelated compounds in titration
and cross-reactivity studies. Both approaches yielded low microgram per milliliter detection limits for MPA with generally
low levels of cross-reactivity for unrelated compounds. However, the data suggest a pattern of traits that may effect the
direction (lights on or off) and intensity of the FRET. 相似文献
883.
Fabrício RS Pereira Andréa Alessio Maurício S Sercheli Tatiane Pedro Elizabeth Bilevicius Jane M Rondina Helka FB Ozelo Gabriela Castellano Roberto JM Covolan Benito P Damasceno Fernando Cendes 《BMC neuroscience》2010,11(1):1-13
Background
Recent studies have shown that the human right-hemispheric auditory cortex is particularly sensitive to reduction in sound quality, with an increase in distortion resulting in an amplification of the auditory N1m response measured in the magnetoencephalography (MEG). Here, we examined whether this sensitivity is specific to the processing of acoustic properties of speech or whether it can be observed also in the processing of sounds with a simple spectral structure. We degraded speech stimuli (vowel /a/), complex non-speech stimuli (a composite of five sinusoidals), and sinusoidal tones by decreasing the amplitude resolution of the signal waveform. The amplitude resolution was impoverished by reducing the number of bits to represent the signal samples. Auditory evoked magnetic fields (AEFs) were measured in the left and right hemisphere of sixteen healthy subjects.Results
We found that the AEF amplitudes increased significantly with stimulus distortion for all stimulus types, which indicates that the right-hemispheric N1m sensitivity is not related exclusively to degradation of acoustic properties of speech. In addition, the P1m and P2m responses were amplified with increasing distortion similarly in both hemispheres. The AEF latencies were not systematically affected by the distortion.Conclusions
We propose that the increased activity of AEFs reflects cortical processing of acoustic properties common to both speech and non-speech stimuli. More specifically, the enhancement is most likely caused by spectral changes brought about by the decrease of amplitude resolution, in particular the introduction of periodic, signal-dependent distortion to the original sound. Converging evidence suggests that the observed AEF amplification could reflect cortical sensitivity to periodic sounds. 相似文献884.
Background
Diverse Mouse genetic models of neurodevelopmental, neuropsychiatric, and neurodegenerative causes of impaired cognition exhibit at least four convergent points of synaptic malfunction: 1) Strength of long-term potentiation (LTP), 2) Strength of long-term depression (LTD), 3) Relative inhibition levels (Inhibition), and 4) Excitatory connectivity levels (Connectivity). 相似文献885.
886.
887.
Wei Tong Guan‐Guang Xia Zheng‐Rong Tian Jia Liu Jun Cai Steven L. Suib Jonathan C. Hanson 《ChemInform》2002,33(20):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献