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关键词： Polarization  

摘要： In this paper, the quasi-P wave propagation in epoxy/lead composites is studied by the differential method with polarization stress and polarization momentum. The corresponding differential equations are numerically solved by the fourth-order Runge-Kutta method, and the dynamic effective modulus and density are obtained. Correctness of the results obtained by the differential method is verified by comparing with the results obtained by the self-consistent method as well as experiments. Results show that the dynamic effective modulus L-1133 and L-3333 increase with the increase of aspect ratio delta, whereas L-1111 and L-1122 decrease with the increase of delta. The phase velocity ratio of the quasi-P wave propagation in the composites tends to 1 when the dimensionless wave number is large, and the dynamic effective density and modulus obtained are not isotropic when delta & NOTEQUAL;1. It is believed that the differential method can be a choice for solving dynamic effective properties of heterogeneous composites.

关键词： negative differential resistance (NDR)   WS2 QDs   carrier injection   trapped states   amino functionalization   >  

摘要： Understanding the mechanism of the negative differential resistance (NDR) in transition metal dichalcogenides is essential for fundamental science and the development of electronic devices. Here, the NDR of the current-voltage characteristics was observed based on the glutamine-functionalized WS2 quantum dots (QDs). The NDR effect can be adjusted by varying the applied voltage range, air pressure, surrounding gases, and relative humidity. A peak-to-valley current ratio as high as 6.3 has been achieved at room temperature. Carrier trapping induced by water molecules was suggested to be responsible for the mechanism of the NDR in the glutamine-functionalized WS2 QDs. Investigating the NDR of WS2 QDs may promote the development of memory applications and emerging devices.

关键词： Core   Numerical modelling   Wave propagation  

摘要： The velocity structure of the uppermost part of the outer core can be investigated seismologically based on the differential traveltimes between the SKKS and S3KS waves (S3KS-SKKS). We develop a procedure for the automatic measurement and quality assessment of the S3KS-SKKS differential traveltime measurements. Four criteria with empirically determined thresholds are used to quantify the quality of the measurements in our automatic algorithm, which greatly simplifies the data quality control. Measurements obtained in the epicentral distance range of 120-140 degrees display positive residuals relative to PREM with no obvious spatial dependency. Waveform simulations in both PREM and S40RTS models show that neither finite-frequency effects nor large-scale mantle heterogeneities can fully explain the magnitude of the observed residuals. Mantle heterogeneities have a significant contribution to the data uncertainty, but do not have sufficient effect on the mean finite-frequency correction. We thus conclude that the observed residuals in the S3KS-SKKS differential traveltimes after finite-frequency correction are mainly caused by the velocity structure in the uppermost outer core.

摘要： 197-Pos

摘要： 2544-Pos

关键词： dentate gyrus   feedback inhibition   GABA   parvalbumin   semilunar granule cell  

摘要： Strong inhibitory synaptic gating of dentate gyrus granule cells (GCs), attributed largely to fast-spiking parvalbumin inter neurons (PV-INs), is essential to maintain sparse network activity needed for dentate dependent behaviors. However, the contribution of PV-INs to basal and input-driven sustained synaptic inhibition in GCs and semilunar granule cells (SGCs), a sparse morphologically distinct dentate projection neuron subtype, is currently unknown. In studies conducted in hippocampal slices from mice, we find that although basal IPSCs are more frequent in SGCs and optical activation of PV-INs reliably elicited IPSCs in both GCs and SGCs, optical suppression of PV-INs failed to reduce IPSC frequency in either cell type. Amplitude and kinetics of IPSCs evoked by perforant path (PP) activation were not different between GCs and SGCs. However, the robust increase in sustained polysynaptic IPSCs elicited by paired afferent stimulation was lower in SGCs than in simultaneously recorded GCs. Optical suppression of PV-IN selectively reduced sustained IPSCs in SGCs but not in GCs. These results demonstrate that PV-INs, while contributing minimally to basal synaptic inhibition in both GCs and SGCs in slices, mediate sustained feedback inhibition selectively in SGCs. The temporally selective blunting of activity-driven sustained inhibitory gating of SGCs could support their preferential and persistent recruitment during behavioral tasks.