Azimuthal polarized quasi-bound states in the continuum based on rotational symmetry breaking.

Bound states in the continuum (BICs) allow to obtain an ultrahigh-quality-factor optical cavity. Nevertheless, BICs must be extended in one or more directions, substantially increasing the device footprint. Although super-cavity mode quasi-BICs supported by single nanopillars have been demonstrated recently, their low-quality factor and localized electromagnetic field inside the dielectric nanopillar are insufficient for high-sensitivity refractive index sensing applications. We propose a ring structure rotated by a dielectric sectorial nanostructure, which can achieve a high quality factor by breaking the rotational symmetry of the ring structure with a footprint as small as 3 µm2. As a straightforward application, we demonstrate high performance local refractive index and nanoscale film thickness sensing based on rotational symmetry breaking induced BICs. These BICs reach quality factor and sensitivity of one order of magnitude better than those of conventional super-cavity mode BICs. The proposed method provides insights into the design of compact high quality factor photonic devices, opening up new possibilities for applications in refractive index and nanoscale film thickness sensing.

Effective removal of sulfur from high-sulfur coal prior to use by dry chlorination at low temperature.

Desulfurization of high-sulfur coal prior to use by dry chlorination under various conditions was investigated. The contents of total carbon, total sulfur, pyritic sulfur, sulfate and organic sulfur of the coal were 72.48, 5.95, 1.08, 0.66 and 4.22 wt.%, respectively. It was found that the chlorination temperature and particle size had a great influence on sulfur removal. The optimal chlorination temperature and particle size for sulfur removal was 350°C and 48-75 µm, respectively. Under optimal conditions, sulfur content in the chlorinated coal was 1.12 wt.%. The removal percentages of total sulfur, pyritic sulfur, sulfate and organic sulfur were 67.7, 93.0, 65.6 and 61.6, respectively, indicating that a high proportion of organic sulfur, pyritic sulfur and inorganic sulfur were removed by dry chlorination. Meanwhile, the fixed carbon did not lose appreciably. It was speculated that the removal of organic sulfur by dry chlorination at 350°C proceeded mainly based on the equation 2RS+Cl(2)=2RCl+S(2)Cl(2). The chlorinated coal thus obtained could be used in production of various carbon-containing materials such as metallurgical coke after a complete dechlorination pretreatment at 500-600°C.

Selective adsorption of Pt ions from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion exchange resin Diaion WA21J.

Thermodynamic and kinetics studies for adsorption of Pt ions complexes from the chloride solutions obtained by leaching chlorinated spent automotive catalysts on anionic exchange resin Diaion WA21J were carried out. It was found that only Si, Pt, Rh and Pd from the solution were selectively adsorbed on the resin Diaion WA21J more strongly. The adsorption equilibrium time for Pt ions was about 20 h. The isothermal adsorption of Pt ions was found to fit Langmuir, Freundlich and DKR models. The maximum monolayer adsorption capacities Q(max) and X(m) of Pt ions on the resin based on Langmuir and DKR model were 4.85, 5.36 and 5.69 mg/g as well as 5.01, 5.63 and 5.98 mg/g for temperatures 18°C, 28°C and 40°C, respectively. The apparent adsorption energy E(ad) based on DKR model were -11.79, -11.04 and -11.04 kJ/mol for the temperatures 18°C, 28°C and 40°C, respectively. Ion exchange was the mechanism involved in the adsorption process. The adsorption of Pt ions on the resin underwent pseudo-first-order kinetic process, and the apparent adsorption activation energy E(a,1) was 12.6 kJ/mol. The intraparticle diffusion of Pt ions was a main rate-controlling step in most of time of adsorption process.