Quantum Yield of Single Surface Plasmons Generated by a Quantum Dot Coupled with a Silver Nanowire

The interactions between surface plasmons (SPs) in metal nanostructures and excitons in quantum emitters (QEs) lead to many interesting phenomena and potential applications that are strongly dependent on the quantum yield of SPs. The difficulty in distinguishing all the possible exciton recombination channels hinders the experimental determination of SP quantum yield. Here, we experimentally measured for the first time the quantum yield of single SPs generated by the exciton–plasmon coupling in a system composed of a single quantum dot and a silver nanowire (NW). By utilizing the SP guiding property of the NW, the decay rates of all the exciton recombination channels, i.e., direct free space radiation channel, SP generation channel, and nonradiative damping channel, are quantitatively obtained. It is determined that the optimum emitter-NW coupling distance for the largest SP quantum yield is about 10 nm, resulting from the different distance-dependent decay rates of the three channels. These results are important for manipulating the coupling between plasmonic nanostructures and QEs and developing on-chip quantum plasmonic devices for potential nanophotonic and quantum information applications

Low Frequency Vibration Assisted Catalytic Aquathermolysis of Heavy Crude Oil

Low frequency vibration was applied to assist the catalytic aquathermolysis reaction of heavy oil for the first time. The optimum vibration parameters were first optimized by orthogonal experiments: vibration acceleration is 3 m·s^–2, vibration time is 90 min, and vibration frequency is 20 Hz, and the efficient consequences of the parameters are as follows: vibration acceleration > vibration time > vibration frequency. Under the optimum vibration parameters, heavy oil viscosity could be reduced by 88.2% after reaction, and the viscosity bounce rate of treated oil is 4.9%. To evaluate the vibration’s performance, the structure and group compositions of the oil before and after reaction were characterized by modern chemical analysis techniques, such as column chromatography, elemental analysis, gas chromatography, and Fourier transform infrared spectrometery. It is found that vibration cannot initiate new reactions in the process of catalytic aquathermolysis, but it can promote the original reactions and deepen the reaction degree such as dealcoholization reaction, hydrogenation reaction, ring-opening reaction, and alkyl side chain removal reaction, etc. Compared to catalytic aquathermolysis reaction, vibration assisted catalytic aquathermolysis can further decrease the average molecular weight of heavy oil, increase the saturate and aromatic contents, decrease the resin and asphaltene contents, improve the ratio of <i>N</i>_H/<i>N</i>_C, and decrease the heteroatoms content of heavy oil. Vibration plays more important role in the in situ catalytic aquathermolysis reactions due to the fact that vibration could aid to reduce the adsorption of catalyst and help the catalysts contact with heavy oil sufficiently in the porous media. The preliminary results proved that the vibration assisted in situ catalytic aquathermolysis technique is feasible and it has some practical value

Resolving Single Plasmons Generated by Multiquantum-Emitters on a Silver Nanowire

Surface plasmons, the collective oscillations of electrons at metal surface, provide the ability to enhance the weak interaction between individual quantum emitters and photons for quantum information applications. The generation of single plasmons by coupling silver nanowire with single quantum emitters opens the prospects of using quantum optical techniques to control single surface plasmons and designing novel quantum plasmonic devices. However, the real applications will deal with multiple plasmons generated from multiple quantum emitters. Here we report the first experimental demonstration of resolving single plasmons generated by a pair of quantum dots (QDs) on a silver nanowire waveguide. The accurate positions of the two QDs with separation ranging from micrometers to 200 nm within the diffraction limit are determined by using super-resolution imaging method. The efficiency of plasmon generation due to the exciton–plasmon coupling is obtained for each QD. Our research takes a crucial step toward the experimental study of coupled systems of multiple quantum emitters and plasmonic waveguides and would shed new light on the study of light-matter interactions for potential quantum optics and quantum information applications

Plasmon-Assisted Selective and Super-Resolving Excitation of Individual Quantum Emitters on a Metal Nanowire

Hybrid systems composed of multiple quantum emitters coupled with plasmonic waveguides are promising building blocks for future integrated quantum nanophotonic circuits. The techniques that can super-resolve and selectively excite contiguous quantum emitters in a diffraction-limited area are of great importance for studying the plasmon-mediated interaction between quantum emitters and manipulating the single plasmon generation and propagation in plasmonic circuits. Here we show that multiple quantum dots coupled with a silver nanowire can be controllably excited by tuning the interference field of surface plasmons on the nanowire. Because of the period of the interference pattern is much smaller than the diffraction limit, we demonstrate the selective excitation of two quantum dots separated by a distance as short as 100 nm. We also numerically demonstrate a new kind of super-resolution imaging method that combines the tunable surface plasmon interference pattern on the NW with the structured illumination microscopy technique. Our work provides a novel high-resolution optical excitation and imaging method for the coupled systems of multiple quantum emitters and plasmonic waveguides, which adds a new tool for studying and manipulating single quantum emitters and single plasmons for quantum plasmonic circuitry applications

Midgut transcriptomal response of the rice leaffolder, <i>Cnaphalocrocis medinalis</i> (Guenée) to Cry1C toxin

<div><p><i>Cnaphalocrocis medinalis</i> (Guenée) is one of the important insect pests in rice field. Bt agents were recommended in the <i>C</i>. <i>medinalis</i> control and Bt rice is bred as a tactic to control this insect. However, the tolerance or resistance of insect to Bt protein is a main threat to the application of Bt protein. In order to investigate the response of <i>C</i>. <i>medinalis</i> transcriptome in defending a Cry1C toxin, high-through RNA-sequencing was carried in the <i>C</i>. <i>medinalis</i> larvae treated with and without Cry1C toxin. A total of 35,586 high-quality unigenes was annotated in the transcriptome of <i>C</i>. <i>medinalis</i> midgut. The comparative analysis identified 6,966 differently expressed unigenes (DEGs) between the two treatments. GO analysis showed that these genes involved in proteolysis and extracellular region. Among these DEGs, carboxylesterase, glutathione S-transferase and P450 were differently expressed in the treated <i>C</i>. <i>medinalis</i> midgut. Furthermore, trypsin, chymotrypsin, and carboxypeptidase were identified in DEGs, and most of them up-regulated. In addition, thirteen ABC transporters were downregulated and three upregulated in Cry1C-treated <i>C</i>. <i>medinalis</i> midgut. Based on the pathway analysis, antigen processing and presentation pathway, and chronic myeloid leukemia pathway were significant in <i>C</i>. <i>medinalis</i> treated with Cry1C toxin. These results indicated that serine protease, detoxification enzymes and ABC transporter, antigen processing and presentation pathway, and chronic myeloid leukemia pathway may involved in the response of <i>C</i>. <i>medinalis</i> to Cry1C toxin. This study provides a transcriptomal foundation for the identification and functional characterization of genes involved in the toxicity of Bt Cry protein against <i>C</i>. <i>medinalis</i>, and provides potential clues to the studies on the tolerance or resistance of an agriculturally important insect pest <i>C</i>. <i>medinalis</i> to Cry1C toxin.</p></div

ABC transporters differently expressed in <i>Cnaphalocrocis medinalis</i> larvae treated with Cry1C toxin.

<p>ABC transporters differently expressed in <i>Cnaphalocrocis medinalis</i> larvae treated with Cry1C toxin.</p

Trypsin genes of <i>Cnaphalocrocis medinalis</i> midgut in response to the ingestion of Cry1C toxin.

<p>Trypsin genes of <i>Cnaphalocrocis medinalis</i> midgut in response to the ingestion of Cry1C toxin.</p

Differentially expressed unigenes (DEGs) in the midgut of <i>Cnaphalocrocis medinalis</i> larvae fed with Cry1C toxin.

<p>(A) Number of DEGs. (B) Volcano plot to show the fold change and error rates. The non-DEGs are indicated by black dots, the DEGs up-regulated are indicated by red dots, and the DEGs down-regulated are indicated by blue dots.</p