Near-field spectroscopy of bimodal size distribution of InAs/AlGaAs quantum dots

We report on high-resolution photoluminescence (PL) spectroscopy of spatial structure of InAs/AlGaAs quantum dots (QDs) by using a near-field scanning optical microscope (NSOM). The double-peaked distribution of PL spectra is clearly observed, which is associated with the bimodal size distribution of single QDs. In particular, the size difference of single QDs, represented by the doublet spectral distribution, can be directly observed by the NSOM images of PL.Comment: 3pages, 3figue

THE EFFECTS OF GREEN HOTEL PRACTICES ON HOTEL IMAGE, VISIT INTENTION, AND WORD-OF-MOUTH: FOCUSING ON THE MODERATING ROLES OF CONSUMER ENVIRONMENTAL WORLDVIEWS

The objective of this study is to empirically examine the effects of hotel green practices on the image of firms, visit intention, and word-of-mouth. In addition, this study examines the moderating effect of an environmental worldview regarding green hotel attributes and image, and visit intention. A self-administrated survey will be conducted to collect data. For data analysis, simple descriptive statistics, factor analysis, and SEM will be utilized to confirm causal relationships among projected constructs. The results of this study will help hoteliers and hotel developers to understand what green hotel attributes are important and necessary to build favorable hotel images, and help researchers to develop future research projects relating to environmental hotel attributes and consumer behaviors.&nbsp

Heat dissipation and its relation to thermopower in single-molecule junctions

Motivated by recent experiments [Lee et al. Nature 498, 209 (2013)], we present here a detailed theoretical analysis of the Joule heating in current-carrying single-molecule junctions. By combining the Landauer approach for quantum transport with ab initio calculations, we show how the heating in the electrodes of a molecular junction is determined by its electronic structure. In particular, we show that in general the heat is not equally dissipated in both electrodes of the junction and it depends on the bias polarity (or equivalently on the current direction). These heating asymmetries are intimately related to the thermopower of the junction as both these quantities are governed by very similar principles. We illustrate these ideas by analyzing single-molecule junctions based on benzene derivatives with different anchoring groups. The close relation between heat dissipation and thermopower provides general strategies for exploring fundamental phenomena such as the Peltier effect or the impact of quantum interference effects on the Joule heating of molecular transport junctions.Comment: 26 pages, 9 figures, submitted to New Journal of Physic

Highly efficient plasmonic organic optoelectronic devices based on a conducting polymer electrode incorporated with silver nanoparticles

Highly efficient ITO-free polymeric electronic devices were successfully demonstrated by replacement of the ITO electrode with a solution-processed PEDOT:PSS electrode containing Ag nanoparticles (NPs). Polymer solar cells (PSCs) and light emitting diodes (PLEDs) were fabricated based on poly(5,6-bis(octyloxy)-4-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole) (PTBT):PC61BM and Super Yellow as a photoactive layer, respectively. The surface plasmon resonance (SPR) effect and improved electrical conductivity by the Ag NPs clearly contributed to increments in light absorption/emission in the active layer as well as the conductivity of the PEDOT:PSS electrode in PSCs and PLEDs. The ITO-free bulk heterojunction PSCs showed a 1% absolute enhancement in the power conversion efficiency (3.27 to 4.31%), and the power efficiency of the PLEDs was improved by 124% (3.75 to 8.4 lm W-1) compared to the reference devices without Ag NPs. The solution-processable conducting polymer, PEDOT:PSS with Ag NPs, can be a promising electrode for large area and flexible optoelectronic devices with a low-cost fabrication process.close11

Ultra-High Vacuum Scanning Thermal Microscopy for Nanometer Resolution Quantitative Thermometry

Understanding energy dissipation at the nanoscale requires the ability to probe temperature fields with nanometer resolution. Here, we describe an ultra-high vacuum (UHV)-based scanning thermal microscope (SThM) technique that is capable of quantitatively mapping temperature fields with ∼15 mK temperature resolution and ∼10 nm spatial resolution. In this technique, a custom fabricated atomic force microscope (AFM) cantilever, with a nanoscale Au–Cr thermocouple integrated into the tip of the probe, is used to measure temperature fields of surfaces. Operation in an UHV environment eliminates parasitic heat transport between the tip and the sample enabling quantitative measurement of temperature fields on metal and dielectric surfaces with nanoscale resolution. We demonstrate the capabilities of this technique by directly imaging thermal fields in the vicinity of a 200 nm wide, self-heated, Pt line. Our measurements are in excellent agreement with computational resultsunambiguously demonstrating the quantitative capabilities of the technique. UHV-SThM techniques will play an important role in the study of energy dissipation in nanometer-sized electronic and photonic devices and the study of phonon and electron transport at the nanoscale

Vitamin B12 auxotrophy of the red tide dinoflagellate Heterocapsa rotundata and the effects of feeding on Synechococcus and vitamin B12 availability upon phagotrophic activity

Vitamins are an important growth factor for the majority of microalgae. Although the effects of light and prey availability on the growth and feeding of mixotrophic dinoflagellates are relatively well understood, the effects of vitamins are currently poorly understood. We investigated the effects of vitamin conditions on feeding by the red tide-forming dinoflagellate Heterocapsa rotundata SIOHR01 on the cyanobacterium Synechococcus sp. CC9311. Furthermore, we explored the growth rates of H. rotundata with and without added prey under different vitamin conditions and found that H. rotundata is auxotrophic for vitamin B-12. Heterocapsa rotundata SIOHR01 was able to ingest Synechococcus sp. CC9311 with maximum ingestion and clearance rates, in f/2-Si seawater media, of 0.72 cells predator(-1) h(-1) and 28.08 nl predator(-1) h(-1), respectively; these were considerably higher than those in f/2-Si seawater media without B vitamins, which showed a maximum of 0.15 cells predator(-1) h(-1) and 2.91 nl predator(-1) h(-1), respectively. However, the mixotrophic growth rate of H. rotundata on Synechococcus sp. under each vitamin condition was similar to that of its autotrophic growth rates without added prey under the same vitamin condition. Therefore, this study suggests that while the availability of prey did not enhance the growth of H. rotundata, the concentration of vitamin in the medium affected growth, apparently due to the auxotrophic requirement of the dinoflagellate for vitamin B-12.N

The red-tide ciliate Mesodinium rubrum in Korean coastal waters

Mesodinium rubrum is a cosmopolitan red tide ciliate and also an obligate mixotroph requiring cryptophycean prey to sustain photosynthesis and growth. Bloom formation by M. rubrum has been recorded in Korea since early 1980s. As part of these records, 40 cases of M. rubrum outbreaks in Korean coastal waters during last three decades were archived in Red Tide Monitoring Dataset of the National Fisheries Research and Development Institute of Korea. Distribution and ecology of Korean M. rubrum populations were first reported in an article about the red tide occurrence and species succession in Jinhae Bay (Park et al., 1988). The first ever temperate strain of M. rubrum was established from Gomso Bay, Korea in 2002 (Yih et al., 2004a), which was followed by a series of research on the biological and ecophysiological characteristics of the ciliate strain MR-MAL01 and then by the first successful cultivation of a DSP dinoflagellate, Dinophysis acuminata strain DA-MAL01 in 2006. Here, we summarize occurrence of M. rubrum in Korean coastal waters encompassing from the national wide long-term monitoring program to the spatiotemporally fine-scaled regional studies. In parallel, we review previous ecophysiological researches using Korean M. rubrum cultures and finally added our perspectives on the future directions of M. rubrum research in Korea. (C) 2013 Elsevier B.V. All rights reserved.N