Diameter InSb Research Articles

5‐HT7 Receptors Mediate Dilation of Rat Cremaster Muscle Arterioles in vivo

Serotonin (5‐HT) infusion in vivo causes hypotension and a fall in total peripheral resistance (TPR) that is mediated by 5‐HT7 receptors. 5‐HT dilates small arterioles in skeletal muscle, a microcirculation that importantly contributes to TPR. However, the receptors that mediate this dilation have not been established. Therefore, we tested the hypothesis that 5‐HT7 receptors mediate the arteriolar dilation in the skeletal muscle microcirculation. Cremaster muscles of isoflurane‐anesthetized male Sprague‐Dawley rats were prepared for digital in vivo microscopy and superfused with physiological salt solution (PSS) at 34 °C. Bolus (1‐10 nmols) application of 5‐HT into the superfusate caused substantial dilation of 3rd to 5th order arterioles from 10 ± 1 to 27 ± 1 μm (n = 10 arterioles from 4 rats, p <0.0001) that recovered within 2‐3 min. Dilation to bolus application of 5‐HT was inhibited by superfusion with 1 μM SB269970, a selective 5‐HT7 receptor antagonist (diameter in SB = 9 ± 1 μm; diameter in SB + 5‐HT = 10 ± 1 μm; n = 10 arterioles from 4 rats; p = 0.8763). Similarly, steady‐state superfusion with 10‐30 nM of the 5‐HT1/7 receptor agonist 5‐carboxamidotryptamine (5‐CT) dilated 3rd‐5th‐order arterioles from 16 ± 3 to 37 ± 5 μm (n = 7 arterioles from 3 rats, p = 0.0004). This dilation was reversed (diameter in 1 μM SB269970 = 13 ± 2 μm, n = 7, p = 0.1479 vs. baseline) or blocked (diameter in 1 μM SB269970 + 10‐30 nM 5‐CT = 10 ± 2 μm, n = 7, p = 0.0005 vs. 5‐CT alone) by 1 μM SB269970. Dilation of arterioles to the muscarinic agonist, methacholine (MCH) was not inhibited by SB269970 verifying the specificity of the antagonist; arterioles dilated from 13 ± 2 μm to 25 ± 2 μm to 100 nmols MCH and dilated from 9 ± 2 μm to 32 ± 2 μm in response to MCH in the presence of 1 μM SB269970; n = 10 arterioles from 4 rats; p = 0.7232 vs. dilation in the absence of SB269970. Consistent with these data, pooled samples (4‐5 rats) of 1st and 2nd – order cremaster arterioles expressed message for 5‐HT7 receptors by quantitative real‐time PCR (CT = 36.4 ± 0.74, n = 3 pooled samples, p = 0.039 vs CT = 40). These data support our hypothesis that 5‐HT7 receptors mediate dilation of small arterioles in skeletal muscle and likely contribute to the observed hypotension when these receptors are engaged in vivo.

New physical insight in structural and electronic properties of InSb nano-sheet being rolled up into single-wall nanotubes

The structure evolution and the electronic properties of InSb monolayers and nanotubes were thoroughly studied by first-principles theory. The results showed that InSb monolayer exhibits intrinsic electric polarization of 12 pC/m, and the direction of electric polarization can be switched when strain or external electric fields are applied. InSb monolayer has a high electron and hole-mobility of ~7 × 103 and 0.7 × 102, respectively. When the monolayer is rolled up to form nanotubes, the optimized parameters, energy level, and electronic structure, were calculated for the armchair and the zigzag configurations. The calculated electronic structure shows that the monolayer has a direct band gap of 1.29 eV, while after being rolled up into small diameter InSb [6] and InSb (6,0) nanotubes, there is an increase of the band gap to 1.58 and 1.70 eV for the two aforementioned configurations, respectively. Furthermore, the strain energy of the nanotubes is lower than that of the monolayer. The increase of band gap when the monolayer was rolled up into nanotubes was attributed to p-p coupling between In-3p orbital in the conduction band of InSb in nanotubes. The findings of the present work suggest that InSb monolayer may have observable ferroelectricity; thus, it can qualify for consideration in information storage applications.

Modulating spin relaxation in nanowires with infrared light at room temperature

Spintronic devices usually rely on long spin relaxation times and/or long spin relaxation lengths for optimum performance. Therefore, the ability to modulate these quantities with an external agent offers unique possibilities. The dominant spin relaxation mechanism in most technologically important semiconductors is the D’yakonov–Perel’ (DP) mechanism which may vanish if the spin carriers (electrons) are confined to a single conduction subband in a quantum wire. Here, we report modulating the DP spin relaxation rate (and hence the spin relaxation length) in self assembled 50 nm diameter InSb nanowires with infrared (IR) light at room temperature. In the dark, almost all the electrons in the nanowires are in the lowest conduction subband, resulting in near-complete absence of DP relaxation. This allows observation of spin-sensitive effects in the magnetoresistance. Under IR illumination, higher subbands get populated and the DP spin relaxation mechanism is revived, leading to a three-fold decrease in the spin relaxation length. Consequently, the spin sensitive effects disappear under illumination. This phenomenon may have applications in spintronic room-temperature IR photodetection.

High density near amorphous InSb nanowire arrays and its photo-electric performance

In this paper, we report the fabrication of high density near amorphous InSb nanowire arrays with using 30, 55 and 70nm diameter anodic alumina oxide (AAO) template by electrodeposition method. The near amorphous structure was proved by combining the results of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Different from the bulk material, these nanowires are black and could not be analyzed by the traditional method, and the reason was discussed. By testing of the photo-electric performance, the 30nm diameter InSb nanowire showed the best performance, which could be used at about 260K. The formation of the near amorphous structure was also discussed. Such high density nanoarrays may found potential application in the infrared detection field.

Coherent spin transport and suppression of spin relaxation in InSb nanowires with single subband occupancy at room temperature.

A longstanding goal of spintronics is to inject, then coherently transport, and finally detect electron spins in a semiconductor nanowire in which a single quantized subband is occupied by the electrons at room temperature. Here, the achieving of this goal in electrochemically self-assembled 50-nm diameter InSb nanowires is reported and substantiated by demonstrating both the spin-valve effect and the Hanle effect. Observing both effects in the same sample allows one to estimate the electron mobility and the spin relaxation time in the nanowires. It is found that despite four orders of magnitude degradation in the mobility compared to bulk or quantum wells and a resulting four orders of magnitude increase in the Elliott-Yafet spin relaxation rate, the spin relaxation time in the nanowires is still about an order of magnitude longer than what has been reported in bulk and quantum wells. This is caused by the elimination or suppression of the D'yakonov-Perel' spin relaxation through single subband occupancy. These experiments shed light on the nature of spin transport in a true quantum wire and raise hopes for the realization of a room-temperature Datta-Das spin transistor, where single subband occupancy is critical for optimum performance.

Time-Resolved X-ray Diffraction Investigation of the Modified Phonon Dispersion in InSb Nanowires

The modified phonon dispersion is of importance for understanding the origin of the reduced heat conductivity in nanowires. We have measured the phonon dispersion for 50 nm diameter InSb (111) nanowires using time-resolved X-ray diffraction. By comparing the sound speed of the bulk (3880 m/s) and that of a classical thin rod (3600 m/s) to our measurement (2880 m/s), we conclude that the origin of the reduced sound speed and thereby to the reduced heat conductivity is that the C44 elastic constant is reduced by 35% compared to the bulk material.