Zhiyuan Qi

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Condensed matter systems with topological defects in the ground states range from the Abrikosov phases in superconductors, to various blue phases and twist grain boundary phases in liquid crystals, and to phases of skyrmion lattices in chiral ferromagnets and Bose-Einstein condensates. In nematic and chiral nematic liquid crystals, which are true fluids(More)
We report the synthesis, structural characterization, thermal stability study, and regeneration of nanostructured catalysts made of 2.9 nm Pt nanoparticles sandwiched between a 180 nm SiO2 core and a mesoporous SiO2 shell. The SiO2 shell consists of 2.5 nm channels that are aligned perpendicular to the surface of the SiO2 core. The nanostructure mimics Pt(More)
Topological defect lines are ubiquitous and important in a wide variety of fascinating phenomena and theories in many fields ranging from materials science to early-universe cosmology, and to engineering of laser beams. However, they are typically hard to control in a reliable manner. Here we describe facile erasable "optical drawing" of self-assembled(More)
To establish the structure-catalytic property relationships of heterogeneous catalysts, a detailed characterization of the three-dimensional (3D) distribution of active sites on a single catalyst is essential. Single-particle catalysis of a modular multilayer catalytic platform that consists of a solid silica core, a mesoporous silica shell, and uniformly(More)
Few-layer graphene (FLG) supported ruthenium nanoparticle catalysts were synthesized and used for the hydrogenation of levulinic acid (LA), one of the “top 10” biomass platform molecules derived from carbohydrates. FLG-supported ruthenium catalyst showed 99.7% conversion and 100% selectivity toward γ-valerolactone (GVL) at room temperature in a batch(More)
The facile pyrolysis of a bipyridyl metal-organic framework, MOF-253, produces N-doped porous carbons (Cz-MOF-253), which exhibit excellent catalytic activity in the Knoevenagel condensation reaction and outperform other nitrogen-containing MOF-derived carbons. More importantly, by virtue of their high Lewis basicity and porous nature, Cz-MOF-253-supported(More)
Wind solar hybrid power utilizing wind and solar complementary can improve the continuity of load power. An optimal configuration of wind solar hybrid power generation system is studied in this paper. Correlation between wind power and solar power is analyzed. Least squares method is used to calculate marginal probability density of wind speed. Mean and(More)
In order to improve the output waveform quality and reduce the circulation of current in parallel inverter system, droop control that is combined with double loop control is used, and two BP neural network controllers are proposed to control the designed inverter in this paper. One BP neural network control the outer-loop part of voltage to obtain stable(More)
Recently, a facile method for the synthesis of size-monodisperse Pt, Pt3 Sn, and PtSn intermetallic nanoparticles (iNPs) that are confined within a thermally robust mesoporous silica (mSiO2 ) shell was introduced. These nanomaterials offer improved selectivity, activity, and stability for large-scale catalytic applications. Here we present the first study(More)
Thin fluid membranes embedded in a bulk fluid of different viscosity are of fundamental interest as experimental realizations of quasi-two-dimensional fluids and as models of biological membranes. We have probed the hydrodynamics of thin fluid membranes by active microrheology using small tracer particles to observe the highly anisotropic flow fields(More)