Engineering topics

Guo, Min

Publications and source records attributed to Guo, Min.

3 records

DOE OSTI2025

Volumetric imaging of the 3D orientation of cellular structures with a polarized fluorescence light-sheet microscope

Polarized fluorescence microscopy is a valuable tool for measuring molecular orientations in biological samples, but techniques for recovering three-dimensional orientations and positions of fluorescent ensembles are limited. We report a polarized dual-view light-sheet system for determining the diffraction-limited three-dimensional distribution of the orientations and positions of ensembles of fluorescent dipoles that label biological structures. We share a set of visualization, histogram, and profiling tools for interpreting these positions and orientations. We model the distributions based on the polarization-dependent efficiency of excitation and detection of emitted fluorescence, using coarse-grained representations we call orientation distribution functions (ODFs). We apply ODFs to create physics-informed models of image formation with spatio-angular point-spread and transfer functions. We use theory and experiment to conclude that light-sheet tilting is a necessary part of our design for recovering all three-dimensional orientations. We use our system to extend known two-dimensional results to three dimensions in FM1-43-labeled giant unilamellar vesicles, fast-scarlet-labeled cellulose in xylem cells, and phalloidin-labeled actin in U2OS cells. Additionally, we observe phalloidin-labeled actin in mouse fibroblasts grown on grids of labeled nanowires and identify correlations between local actin alignment and global cell-scale orientation, indicating cellular coordination across length scales.

Science & Technology - Other Topics↗

DOE OSTI2024

Epitaxial heterointerfacial electron bridge synchronizes oxygen evolution activity and stability on a layered double hydroxide surface

Scalable green hydrogen production via electrocatalytic water splitting is largely restricted by the insufficient activity and stability of oxygen evolution reaction (OER) catalysts at the anode. As a class of the most active OER catalysts in alkaline electrolyzers, the application of layered double hydroxides (LDHs) remains a main challenge owing to the unstable lattice oxygen dissolution due to the dominant lattice oxygen-involving OER mechanism during long-term operation. Herein, we found that using an epitaxial hetero-interfacing nickel hydroxide (namely Ni(OH) 2 ) as an electron bridge between an active FeCo LDH and Ni foam support to form an LDH*/NFO catalyst, the electronic storage capacity around the Fermi level (-0.5 to +0.5 eV, e-D FE ) sharply increases from 0.93 per cell to 1.51 per cell. Subsequently, we demonstrate that this high e-D FE enables ceaseless and fast power injection into the kinetic process of intermediate species conversion and inhibits lattice oxygen dissolution in the active FeCo LDH. Consequently, it demonstrated a low OER overpotential of 246 mV at a current density of 100 mA cm -2 and ultrahigh stability for up to 3500 hours with an ultraslow overpotential increase rate of 9.4 × 10 -3 mV h -1 . Therefore, we developed an epitaxial hetero-interfacial electron bridging strategy to synchronize the activity and stability of available catalysts for scalable green hydrogen production via electrocatalytic water splitting.

25 ENERGY STORAGE↗

DOE OSTI2023

USc 2 C 2 and USc 2 NC Clusters with U–C Triple Bond Character Stabilized Inside Fullerene Cages

The chemistry of f-block metal–carbon multiple bonds is underdeveloped compared to well-established carbene complexes of the d-block transition metals. Herein, we report two new actinide-rare earth mixed metal carbides and nitrogen carbide cluster fullerenes, USc 2 C 2 @D 5h (6)-C 80 and USc 2 NC@D 5h (6)-C 80 , which contain U–C bonds with triple bond character and were successfully synthesized and characterized by mass spectrometry, UV–vis–NIR spectroscopy, Fourier transform infrared spectroscopy, single crystal X-ray diffraction, and DFT calculations. Crystallographic studies show that the two previously unreported clusters, USc 2 C 2 and USc 2 NC, are stabilized in the D 5h (6)-C 80 carbon cage and adopt unique trifoliate configurations, in which C 2 /NC units are almost vertically inserted into the plane defined by the U and two Sc atoms. Combined experimental and theoretical studies further reveal the bonding structure of USc 2 C 2 and USc 2 NC, which contain C=U(VI)=C and C=U(V)=N bonding motifs. The electronic structures of the two compounds are determined as U 6+ (Sc 2 ) 6+ (C 4– ) 2 @D 5h (6)-C 80 4– and U 5+ (Sc 2 ) 6+ (N) 3– (C) 4– @D 5h (6)-C 80 4– , respectively. Quantum-chemical studies confirm that the U–C bonds in both molecules show unprecedented multicenter triple-bond character. Furthermore, the discovery of this unique U–C multiple bond offers a deeper understanding of the fundamentals of uranium chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗