Broadband enhancement of light harvesting in luminescent solar concentrator

Luminescent solar concentrator (LSC) can absorb large-area incident sunlight, then emit luminescence with high quantum efficiency, which finally be collected by a small photovoltaic (PV) system. The light-harvesting area of the PV system is much smaller than that of the LSC system, potentially improving the efficiency and reducing the cost of solar cells. Here, based on Fermi-golden rule, we present a theoretical description of the luminescent process in nanoscale LSCs where the conventional ray-optics model is no longer applicable. As an example calculated with this new model, we demonstrate that a slot waveguide consisting of a nanometer-sized low-index slot region sandwiched by two high-index regions provides a broadband enhancement of light harvesting by the luminescent centers in the slot region. This is because the slot waveguide can (1) greatly enhance the spontaneous emission due to the Purcell effect, (2) dramatically increase the effective absorption cross-section of luminescent centers, and (3) strongly improve the quantum efficiency of luminescent centers. It is found that about 80% solar photons can be ultimately converted to waveguide-coupled luminescent photons even for a low luminescent quantum efficiency of 0.5. This LSC is potential to construct a tandem structure which can absorb nearly full-spectrum solar photons, and also may be of special interest for building integrated nano-PV applications

Hydrogen sulfide ameliorates isoflurane-induced cognitive impairment in mice: Implication of caspase-3 activation

Purpose: Isoflurane could induce cognitive impairment and activate caspase-3. However, the mechanism of action is unclear and target  interventions are unavailable. The present study examined the potential protective function of hydrogen sulfide (H2S) against isoflurane-induced cognitive impairment.Methods: Effects of NaHS (5 mg/kg) on cognitive impairment induced by isoflurane (1.4% for 2 h) were assessed using a fear-conditioning test in a group of 8-month old mice. H4 human neuroglioma cells, which were transfected with upregulated human amyloid precursor protein were treated for 3 or 6 h with 2% isoflurane, in the presence of 100-μM NaHS in the mice. A group of mice treated with normal saline in place of the NaHS in each case served as control. Western blotting, fluorescence assay, and a mitochondrial swelling assay were employed to observe the results of caspase-3 activation, mitochondrial dysfunction, and ROS and ATP levels.Results: NaHS significantly mitigated isoflurane-induced cognitive impairment in mice. In cultured cells, NaHS reduced caspase-3 activation, ROS, mitochondria membrane reduction, mitochondrial permeability transition pore opening, and cellular ATP level. NaHS could ameliorate cognitiveimpariment induced by isoflurane through inhibiting caspase-3 activation, oxidative stress, and mitochondrial dysfunction.Conclusion: These results indicate that hydrogen sulfide (H2S) has potential protective function against isoflurane-induced cognitive impairment. Further investigation of NaHS as an intervention to attenuate anesthesia-associated neurotoxicity is vital. Keywords: Hydrogen sulfide, isoflurane-cognition，fear conditioning，neurotoxicit

Improving the precision of multiparameter estimation in the teleportation of qutrit under amplitude damping noise

Since the initial discovery of quantum teleportation, it is devoted to transferring unknown quantum states from one party to another distant partner. However, in the scenarios of remote sensing, what people truly care about is the information carried by certain parameters. The problem of multiparameter estimation in the framework of qutrit teleportation under amplitude damping (AD) noise is studied. Particularly, two schemes are proposed to battle against AD noise and enhance the precision of multiparameter estimation by utilizing weak measurement (WM) and environment-assisted measurement (EAM). For two-phase parameters encoded in a qutrit state, the analytical formulas of the quantum Fisher information matrix (QFIM) can be obtained. The results prove that the scheme of EAM outperforms the WM one in the improvements of both independent and simultaneous estimation precision. Remarkably, the EAM scheme can completely ensure the estimation precision against the contamination by AD noise. The reason should be attributed to the fact that EAM is carried out after the AD noise. Thus, it extracts information from both the system and the environment. The findings show that the techniques of WM and EAM are helpful for remote quantum sensing and can be generalized to other qutrit-based quantum information tasks under AD decoherence.Comment: 9 pages, 5 figures, accepted by Annalen der Physi

Feasibility and effectiveness of heat pipe cooling in end milling operations : thermal, structural static, and dynamic analyses : a new approach

In this paper, the feasibility and effectiveness of heat pipe cooling in end milling operations are investigated. A new embedded heat pipe technology was utilized to remove the heat generated at the tool-interface in end milling processes. Numerical studies involved four cases, including dry milling, fluid cooling, heat pipe cooling, and heat pipe cooling with cutting fluid supplied. The thermal, structural static, and dynamic characteristics of the endmill were investigated using a numerical calculation with fast finite element plus solvers based on explicit finite element analysis software. The results demonstrate that the heat pipe end-mill is most feasible and effective in the actual end milling processe