Photoresponse of a Single Y‑Junction Carbon Nanotube

We report investigation of optical response in a single strand of a branched carbon nanotube (CNT), a Y-junction CNT composed of multiwalled CNTs. The experiment was performed by connecting a pair of branches while grounding the remaining one. Of the three branch combinations, only one combination is optically active which also shows a nonlinear semiconductor-like <i>I</i>–<i>V</i> curve, while the other two branch combinations are optically inactive and show linear ohmic <i>I</i>–<i>V</i> curves. The photoresponse includes a zero-bias photocurrent from the active branch combination. Responsivity of ≈1.6 mA/W has been observed from a single Y-CNT at a moderate bias of 150 mV with an illumination of wavelength 488 nm. The photoresponse experiment allows us to understand the nature of internal connections in the Y-CNT. Analysis of data locates the region of photoactivity at the junction of only two branches and only the combination of these two branches (and not individual branches) exhibits photoresponse upon illumination. A model calculation based on back-to-back Schottky-type junctions at the branch connection explains the <i>I</i>–<i>V</i> data in the dark and shows that under illumination the barriers at the contacts become lowered due to the presence of photogenerated carriers

Naturally Occurring Carbazole Alkaloids from <i>Murraya koenigii</i> as Potential Antidiabetic Agents

This study identified koenidine (<b>4</b>) as a metabolically stable antidiabetic compound, when evaluated in a rodent type 2 model (leptin receptor-deficient <i>db/db</i> mice), and showed a considerable reduction in the postprandial blood glucose profile with an improvement in insulin sensitivity. Biological studies were directed from the preliminary in vitro evaluation of the effects of isolated carbazole alkaloids (<b>1</b>–<b>6</b>) on glucose uptake and GLUT4 translocation in L6-GLUT4<i>myc</i> myotubes, followed by an investigation of their activity (<b>2</b>–<b>5</b>) in streptozotocin-induced diabetic rats. The effect of koenidine (<b>4</b>) on GLUT4 translocation was mediated by the AKT-dependent signaling pathway in L6-GLUT4<i>myc</i> myotubes. Moreover, in vivo pharmacokinetic studies of compounds <b>2</b> and <b>4</b> clearly showed that compound <b>4</b> was 2.7 times more bioavailable than compound <b>2</b>, resulting in a superior in vivo efficacy. Therefore, these studies suggested that koenidine (<b>4</b>) may serve as a promising lead natural scaffold for managing insulin resistance and diabetes