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189 results on '"Liu, Maochang"'

1. Non-Hermitian delocalization in a 2D photonic quasicrystal

Author

Zhang, Zhaoyang, Liang, Shun, Septembre, Ismael, Yu, Jiawei, Huang, Yongping, Liu, Maochang, Zhang, Yanpeng, Xiao, Min, Malpuech, Guillaume, and Solnyshkov, Dmitry

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Optics
Abstract

Quasicrystals show long-range order, but lack translational symmetry. So far, theoretical and experimental studies suggest that both Hermitian and non-Hermitian quasicrystals show localized eigenstates. This localization is due to the fractal structure of the spectrum in the Hermitian case and to the transition to diffusive bands via exceptional points in the non-Hermitian case. Here, we present an experimental study of a dodecagonal (12-fold) photonic quasicrystal based on electromagnetically-induced transparency in a Rb vapor cell. The transition to a quasicrystal is obtained by superposing two honeycomb lattices at 30$^\circ$ with a continuous tuning of their amplitudes. Non-Hermiticity is controlled independently. We study the spatial expansion of a probe wavepacket. In the Hermitian case, the wavepacket expansion is suppressed when the amplitude of the second lattice is increased (quasicrystal localization). We find a new regime, where increasing the non-Hermitian potential in the quasicrystal enhances spatial expansion, with the $C_{12}$ symmetry becoming visible in the wavepacket structure. This real-space expansion is due to a k-space localization on specific quasicrystal modes. Our results show that the non-Hermitian quasicrystal behavior is richer than previously thought. The localization properties of the quasicrystals can be used for beam tailoring in photonics, but are also important in other fields.

Published
2023

21. Concentrated solar CO2 reduction in H2O vapour with >1% energy conversion efficiency.

Author

Ren, Yuqi, Fu, Yiwei, Li, Naixu, You, Changjun, Huang, Jie, Huang, Kai, Sun, Zhenkun, Zhou, Jiancheng, Si, Yitao, Zhu, Yuanhao, Chen, Wenshuai, Duan, Lunbo, and Liu, Maochang

Subjects
ENERGY conversion, ENERGY consumption, METHANATION, PHOTOTHERMAL effect, VAPORS, PHOTON flux, ACTIVATION energy
Abstract

H2O dissociation plays a crucial role in solar-driven catalytic CO2 methanation, demanding high temperature even for solar-to-chemical conversion efficiencies <1% with modest product selectivity. Herein, we report an oxygen-vacancy (Vo) rich CeO2 catalyst with single-atom Ni anchored around its surface Vo sites by replacing Ce atoms to promote H2O dissociation and achieve effective photothermal CO2 reduction under concentrated light irradiation. The high photon flux reduces the apparent activation energy for CH4 production and prevents Vo from depletion. The defects coordinated with single-atom Ni, significantly promote the capture of charges and local phonons at the Ni d-impurity orbitals, thereby inducing more effective H2O activation. The catalyst presents a CH4 yield of 192.75 µmol/cm2/h, with a solar-to-chemical efficiency of 1.14% and a selectivity ~100%. The mechanistic insights uncovered in this study should help further the development of H2O-activating catalysts for CO2 reduction and thereby expedite the practical utilization of solar-to-chemical technologies. This work reports a single-atom Ni incorporated CeO2 catalyst that boosts the efficiency of solar CO2 reduction under concentrated light irradiation. [ABSTRACT FROM AUTHOR]

Published
2024
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36. Towards efficient solar-to-hydrogen conversion: Fundamentals and recent progress in copper-based chalcogenide photocathodes

Author

Chen Yubin, Feng Xiaoyang, Liu Maochang, Su Jinzhan, and Shen Shaohua

Subjects
Copper-based chalcogenide, photocathode, water splitting, solar energy, hydrogen, Physics, QC1-999
Abstract

Photoelectrochemical (PEC) water splitting for hydrogen generation has been considered as a promising route to convert and store solar energy into chemical fuels. In terms of its large-scale application, seeking semiconductor photoelectrodes with high efficiency and good stability should be essential. Although an enormous number of materials have been explored for solar water splitting in the last several decades, challenges still remain for the practical application. P-type copper-based chalcogenides, such as Cu(In, Ga)Se2 and Cu2ZnSnS4, have shown impressive performance in photovoltaics due to narrow bandgaps, high absorption coefficients, and good carrier transport properties. The obtained high efficiencies in photovoltaics have promoted the utilization of these materials into the field of PEC water splitting. A comprehensive review on copper-based chalcogenides for solar-to-hydrogen conversion would help advance the research in this expanding area. This review will cover the physicochemical properties of copper-based chalco-genides, developments of various photocathodes, strategies to enhance the PEC activity and stability, introductions of tandem PEC cells, and finally, prospects on their potential for the practical solar-to-hydrogen conversion. We believe this review article can provide some insights of fundamentals and applications of copper-based chalco-genide thin films for PEC water splitting.

Published
2016
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47. How Much Vancomycin Dose Is Enough For The MRSA Infection in Pediatric Patients With Various Degrees of Renal Function?

Author

Wang, Yang, Gao, Ping, Zhang, Huanian, Chen, Yujun, Niu, Changhe, Liu, Maochang, Li, Sichan, Xu, Qiong, and Ye, Qi

Subjects
Population Pharmacokinetics, Drug resistance, vancomycin, Monte Carlo Simulation, Original Article, urologic and male genital diseases, Nephrotoxicity, Children
Abstract

Today, an increase in vancomycin dose has been proposed to ensure efficacy. However, the risk of nephrotoxicity will increase with the dose. The aim of this study was to evaluate the dosage regimens of vancomycin in pediatric patients based on pharmacokinetics/pharmacodynamics (PK/PD) and to optimize dosage individualization. Population pharmacokinetics analysis was performed on 155 Chinese children (aged 1 month to 16 years), which were divided into various renal function subpopulations. Monte Carlo simulation was carried to evaluate the efficacy and safety of vancomycin dosage regimens on each subpopulation. Compared with children with normal renal function as glomerular filtration rate (GFR) ≥ 90 mL/min·1.73 m2, the clearance of vancomycin decreased by 39.4% and the half life increased 1.74 fold respectively in children with moderate renal inadequacy (30 ≤ GFR < 60 mL/min·1.73 m2). When vancomycin was administered as conventional dosage (40-60mg·kg-1·d-1) to against methicillin-resistant staphylococcus aureus (MRSA) with higher MICs of 1-2 mg·L-1 for children with normal renal function, the probability of efficacy target attainment ( PTA) at AUC0-24h/MIC ≥ 400 (where AUC is the area under curve and MIC is the minimum inhibitory concentration) achieved ≤ 63.64%. While vancomycin dosage exceeded 70mg·kg-1·d-1 for children with normal renal function, 50mg·kg-1·d-1 for mild renal inadequacy (60 ≤ GFR < 90 mL/min·1.73 m2), 30 mg·kg-1·d-1 for moderate renal inadequacy respectively, the PTA at trough concentration above 20 mg·L-1 achieved > 20%, that not to be suggested for high risk of nephrotoxicity. Considering both efficacy and safety, the conventional vancomycin dosage is not enough and adjustable interval is narrow for pediatric patients with MIC 1-2 mg·L-1 MRSA infection and normal renal function.

Published
2019

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