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Wang, Guan

Publications and source records attributed to Wang, Guan.

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Interfacial Assembly and Jamming of Soft Nanoparticle Surfactants into Colloidosomes and Structured Liquids

Nanoparticle surfactant (NPS) offers a powerful strategy to generate all-liquid constructs that integrate the inherent properties of the NPs into 3D architectures. In this report using the co-assembly of fluorescent polymeric nanoparticles and amine-functionalized polyhedral oligomeric silsesquioxane, the assembly and jamming behavior of a new type of NPS at the oil-water interface is uncovered. Unlike "solid" inorganic nanoparticles, "soft" polymeric nanoparticles can reorganize when jammed, leading to a relaxation and deformation of the interfacial assemblies, for example, the 3D printed sugar-coated haw stick-like liquid tubules. With NPS serving as emulsifiers, stable Pickering emulsions are prepared that can be converted into robust colloidosomes with pH responsiveness, showing numerous potential applications for encapsulation and controlled release.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Unraveling the Effects of Cobalt on Crystal Growth and Solution Behavior of Nb 6 P 2 W 12 -based Dimeric Clusters

We report the synthesis, characterization, and solution self-assembly of plenary Nb 6 P 2 W 12 -based transition-metal substituted polyoxometalate, which is obtained by simply adding transition metals (Co 2+ ) into aqueous solution containing cluster [(NbO 2 ) 6 P 2 W 12 O 56 ] 12- , which is obtained by an in situ synthetic method. The incorporation of Co 2+ ions significantly affects the crystal structure, resulting in the formation of a 1D chain-like crystal and the first example of a niobotungstate-based cobalt derivative cluster. The behavior and stability of this cluster in solution are confirmed by time-resolved static light scattering, dynamic light scattering, small-angle X-ray scattering, and electrospray mass spectrometry studies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Room-Temperature Microstructural Evolution of Extruded AM80 Magnesium Alloys under Dynamic Loading

Dynamic compression tests were conducted using a split Hopkinson pressure bar along the transverse direction at strain rates (SRs) of 3200 and 6000 s{sup −1}. The initial microstructure significantly affected the flow stress behavior and microstructural evolution of the two studied AM80 magnesium alloys. Under the same SR loading, the as-extruded alloy exhibited an apparently higher flow stress. At a SR of 6000 s{sup −1}, the flow stress of the as-extruded alloy exhibited a visible decrease (~ 34 MPa) as the strain increased to ~ 0.2, whereas a constant flow stress was exhibited by the solution-treated alloy. High-density dislocations and mechanical twins were detected in the two alloys at a SR of 3200 s{sup −1}. Interestingly, dynamic recrystallization (DRX) with an average grain size of ~ 2 µm was only identified in the as-extruded alloy as the applied SR increased to 6000 s{sup −1}. The increased localized deformation in the as-extruded alloy due to the retained strain energy and high critical twinning stress improved the DRX driving force, thereby resulting in visibly different micrographs of the two alloys when impacted at the SR of 6000 s{sup −1}.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Sinomenine alleviates high glucose-induced renal glomerular endothelial hyperpermeability by inhibiting the activation of RhoA/ROCK signaling pathway

As an early sign of diabetic cardiovascular disease, endothelial dysfunction may contribute to progressive diabetic nephropathy (DN). Endothelial hyperpermeability induced by hyperglycemia (HG) is a central pathogenesis for DN. Sinomenine (SIN) has strong anti-inflammatory and renal protective effects, following an unknown protective mechanism against HG-induced hyperpermeability. We herein explored the role of SIN in vitro in an HG-induced barrier dysfunction model in human renal glomerular endothelial cells (HRGECs). The cells were exposed to SIN and/or HG for 24 h, the permeability of which was significantly increased by HG. Moreover, junction protein occludin in the cell-cell junction area and its total expression in HRGECs were significantly decreased by HG. However, the dysfunction of tight junction and hyperpermeability of HRGECs were significantly reversed by SIN. Furthermore, SIN prevented HG-increased reactive oxygen species (ROS) by activating nuclear factor-E2-related factor 2 (Nrf2). Interestingly, activation of RhoA/ROCK induced by HG was reversed by SIN or ROCK inhibitor. HG-induced hyperpermeability was prevented by SIN. High ROS level, tight junction dysfunction and RhoA/ROCK activation were significantly attenuated with knockdown of Nrf2. Mediated by activation of Nrf2, SIN managed to significantly prevent HG-disrupted renal endothelial barrier function by suppressing the RhoA/ROCK signaling pathway through reducing ROS. We successfully identified a novel pathway via which SIN exerted antioxidative and renal protective functions, and provided a molecular basis for potential SIN applications in treating DN vascular disorders.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Off-axis silicon carbide substrates

A method of epitaxial growth of a material on a crystalline substrate includes selecting a substrate having a crystal plane that includes a plurality of terraces with step risers that join adjacent terraces. Each terrace of the plurality or terraces presents a lattice constant that substantially matches a lattice constant of the material, and each step riser presents a step height and offset that is consistent with portions of the material nucleating on adjacent terraces being in substantial crystalline match at the step riser. The method also includes preparing a substrate by exposing the crystal plane; and epitaxially growing the material on the substrate such that the portions of the material nucleating on adjacent terraces merge into a single crystal lattice without defects at the step risers.

36 MATERIALS SCIENCE↗