Single-mode tunable laser emission in the single-exciton regime from colloidal nanocrystals

Whispering-gallery-mode resonators have been extensively used in conjunction with different materials for the development of a variety of photonic devices. Among the latter, hybrid structures, consisting of dielectric microspheres and colloidal core/shell semiconductor nanocrystals as gain media, have attracted interest for the development of microlasers and studies of cavity quantum electrodynamic effects. Here we demonstrate single-exciton, single-mode, spectrally tuned lasing from ensembles of optical antenna-designed, colloidal core/shell CdSe/CdS quantum rods deposited on silica microspheres. We obtain single-exciton emission by capitalizing on the band structure of the specific core/shell architecture that strongly localizes holes in the core, and the two-dimensional quantum confinement of electrons across the elongated shell. This creates a type-II conduction band alignment driven by coulombic repulsion that eliminates non-radiative multi-exciton Auger recombination processes, thereby inducing a large exciton–bi-exciton energy shift. Their ultra-low thresholds and single-mode, single-exciton emission make these hybrid lasers appealing for various applications, including quantum information processing

High-energy, shock-front assisted resonant radiation in the normal dispersion regime

We present a simple yet effective theory that predicts the existence of resonant radiation bands in the deep normal group velocity dispersion region of a medium, even in absence of a zero-group velocity dispersion point. This radiation is evident when the medium is pumped with high-energy ultrashort pulses, and it is driven by the interplay between the Kerr and the shock terms in the NLSE. Accurate experiments performed in bulk silica fully support the theoretical phase-matching condition found by our theory.Comment: 5 pages, 3 figure

The effect of fog on the probability density distribution of the ranging data of imaging laser radar

This paper outlines theoretically investigations of the probability density distribution (PDD) of ranging data for the imaging laser radar (ILR) system operating at a wavelength of 905 nm under the fog condition. Based on the physical model of the reflected laser pulses from a standard Lambertian target, a theoretical approximate model of PDD of the ranging data is developed under different fog concentrations, which offer improved precision target ranging and imaging. An experimental test bed for the ILR system is developed and its performance is evaluated using a dedicated indoor atmospheric chamber under homogeneously controlled fog conditions. We show that the measured results are in good agreement with both the accurate and approximate models within a given margin of error of less than 1%

Hesitant Triangular Fuzzy Information Aggregation Operators Based on Bonferroni Means and Their Application to Multiple Attribute Decision Making

We investigate the multiple attribute decision-making (MADM) problems with hesitant triangular fuzzy information. Firstly, definition and some operational laws of hesitant triangular fuzzy elements are introduced. Then, we develop some hesitant triangular fuzzy aggregation operators based on Bonferroni means and discuss their basic properties. Some existing operators can be viewed as their special cases. Next, we apply the proposed operators to deal with multiple attribute decision-making problems under hesitant triangular fuzzy environment. Finally, an illustrative example is given to show the developed method and demonstrate its practicality and effectiveness

Fabrication and Properties of Carbon- Encapsulated Cobalt Nanoparticles over NaCl by CVD

Carbon-encapsulated cobalt (Co@C) nanoparticles, with a tunable structure, were synthesized by chemical vapor deposition using Co nanoparticles as the catalyst and supported on a water-soluble substrate (sodium chloride), which was easily removed by washing and centrifugation. The influences of growth temperature and time on the structure and magnetic properties of the Co@C nanoparticles were systematically investigated. For different growth temperatures, the magnetic Co nanoparticles were encapsulated by different types of carbon layers, including amorphous carbon layers, graphitic layers, and carbon nanofibers. This inferred a close relationship between the structure of the carbon-encapsulated metal nanoparticles and the growth temperature. At a fixed growth temperature of 400 °C, prolonged growth time caused an increase in thickness of the carbon layers. The magnetic characterization indicated that the magnetic properties of the obtained Co@C nanoparticles depend not only on the graphitization but also on the thickness of the encapsulated carbon layer, which were easily controlled by the growth temperatures and times. Optimization of the synthesis process allowed achieving relatively high coercivity of the synthesized Co@C nanoparticles and enhancement of its ferromagnetic properties, which make this system promising as a magnetic material, particularly for high-density magnetic recording applications

The Critical Role of nπ* States in the Photophysics and Thermally Activated Delayed Fluorescence of Spiro Acridine-Anthracenone

The molecular photophysics and thermally activated delayed fluorescence (TADF) in spiro compounds are distinct because of the rigid orthogonal C–C bridging bond between donor and acceptor. The photophysics is found to be highly complex, with unprecedented multiple anti-Kasha emissions from three different singlet states, two of which are one-photon forbidden. The TADF mechanism is critically controlled by local acceptor nπ* states; the singlet nπ* state undergoes rapid intersystem crossing populating an energetically close acceptor ππ* triplet state. The acceptor triplet nπ* state couples nonadiabatically to a CT triplet state mediating reverse intersystem crossing. When the nπ* and CT states are energetically close, TADF is greatly enhanced with rISC rate reaching 107 s–1. We observe neither DF from the singlet nπ* state nor electron transfer (ET) to form the 1CT because there is no ET driving force; however, ET from the higher-energy donor singlet ππ* state readily occurs along with donor emission

Aqua­azido­{2,2′-[o-phenylenebis(nitrilo­methyl­idyne)]diphenolato}manganese(III) hemihydrate

In the title compound, [Mn(C20H14N2O2)(N3)(H2O)]·0.5H2O, the MnIII ion is chelated by the N,N′,O,O′-tetra­dentate Schiff base ligand and further coordinated by one azide ion and one water mol­ecule in trans positions, resulting in a distorted fac-MnN3O3 octa­hedral arrangement. The O atom of the uncoordinated water mol­ecule lies on a crystallographic twofold axis. In the crystal, O—H⋯O and O—H⋯N hydrogen bonds help to establish the packing

Residual Characteristics and Dietary Risk Assessment of Dinotefuran and Tolfenpyrad in Tea Processing

To clarify the residual characteristics of dinotefuran tolfenpyrad microemulsion during tea planting, drying and brewing, standardized field trials of pesticide registration residues were conducted in 10 provinces including Shandong and Zhejiang. Dietary risk assessment models were compared with and without adjustment of processing factors. The samples were extracted using acetonitrile containing 5% formic acid, salted out, purified by dispersed solid phase extraction, detected by ultra-high performance liquid chromatography-tandem mass spectrometry, and quantified by an external standard method. In the range of 0.005–0.500 µg/mL, a good linear relationship was obtained between the concentrations of dinotefuran and its metabolites as well as tolfenpyrad and their response peak areas (R2 > 0.99). The average recovery rates of dinotefuran and its metabolites 1-methyl-3-(tetrahydro-3-furylmethyl)guanidine (DN) and 1-methyl-3-(tetrahydro-3-furylmethyl)urea (UF) in fresh and dried tea leaves spiked at 0.05, 1.00, 20.00 and 50.00 mg/kg and in tea infusion spiked at 0.05, 0.10 and 5.00 mg/kg ranged from 74% to 103%, with relative standard deviations (RSDs) of 1%–9%. The spiked recovery rates of tolfenpyrad were between 75% and 95%, with RSDs of 1%–6%. The limit of quantitation (LOQ) was 0.05 mg/kg for all the analytes. In the case of the application of 20% dinotefuran·tolfenpyrad microemulsion at the recommended dose, both the national estimated daily intake (NEDI) for supervised trials median residue (STMR) adjusted with the drying factor of dinotefuran (containing its metabolites) in fresh tea leaves and that in dried tea leaves were 4.08 mg, accounting for 32.4% of the acceptable daily intake (ADI). The NEDI for STMR of tolfenpyrad adjusted with the drying factor in fresh tea leaves was 0.175 81 mg, accounting for 46.5% of the ADI, and the NEDI for STMR of tolfenpyrad in dried tea leaves was 0.189 25 mg, accounting for 50.1% of the ADI. According to different risk assessment models, the long-term exposure risk to both dinotefuran and tolfenpyrad was less than 100%. The national estimated short-term intake (IESTI) of dinotefuran (containing its metabolites) remained at the same risk level before and after processing factor adjustment, which was lower than the acute reference dose (ARfD) of 1 mg/kg. The IESTI of tolfenpyrad was 3.46 × 10-4 mg/kg, which was lower than the ARfD of 0.01 mg/kg, and tolfenpyrad residue was below the detectable level under the method established in this study, so no brewing facter and corresponding IESTI were obtained. In conclusion, the application of 20% dinotefuran·tolfenpyrad microemulsion on tea plants is safe at the recommended dose, and the risk of long-term and acute dietary exposure to dinotefuran and tolfenpyrad residues in tea is within the acceptable range. The risk assessment models with processing factor adjustment are closer to the actual risk level

IPC02-27155 DEVELOPMENT OF LARGE DIAMETER X70 HIGH TOUGHNESS HSAW LINEPIPE FOR GAS TRANSMMISION

ABSTRACT X70 large diameter linepipe with helical seam SAW were developed, with1016mm OD and 14.6mm WT. Acicular ferrite type linepipe steel is adopted for the base material, which was found having high toughness and low yield strength loss after pipe forming. The very stringent requirements for toughness, i.e. 190J/140J for average/minimum for pipe body and 120J/90J for average/minimum for weld and HAZ were meet successfully. The yield strength loss due to Bauschinger effect was found lower than 20 MPa, which benefited