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Full-Text Articles in Physics
Interaction Of ΒL- And Γ-Crystallin With Phospholipid Membrane Using Atomic Force Microscopy, Nawal K. Khadka, Preston Hazen, Dieter Haemmerle, Laxman Mainali
Interaction Of ΒL- And Γ-Crystallin With Phospholipid Membrane Using Atomic Force Microscopy, Nawal K. Khadka, Preston Hazen, Dieter Haemmerle, Laxman Mainali
Physics Faculty Publications and Presentations
Highly concentrated lens proteins, mostly β- and γ-crystallin, are responsible for maintaining the structure and refractivity of the eye lens. However, with aging and cataract formation, β- and γ-crystallin are associated with the lens membrane or other lens proteins forming high-molecular-weight proteins, which further associate with the lens membrane, leading to light scattering and cataract development. The mechanism by which β- and γ-crystallin are associated with the lens membrane is unknown. This work aims to study the interaction of β- and γ-crystallin with the phospholipid membrane with and without cholesterol (Chol) with the overall goal of understanding the role of …
Mechanical Properties Of The High Cholesterol-Containing Membrane: An Afm Study, Nawal K. Khadka, Raju Timsina, Erica L. Rowe, Matthew O'Dell, Laxman Mainali
Mechanical Properties Of The High Cholesterol-Containing Membrane: An Afm Study, Nawal K. Khadka, Raju Timsina, Erica L. Rowe, Matthew O'Dell, Laxman Mainali
Physics Faculty Publications and Presentations
Cholesterol (Chol) content in most cellular membranes does not exceed 50 mol%, only in the eye lens’s fiber cell plasma membrane, its content surpasses 50 mol%. At this high concentration, Chol induces the formation of pure cholesterol bilayer domains (CBDs), which coexist with the surrounding phospholipid-cholesterol domain (PCD). Here, we applied atomic force microscopy to study the mechanical properties of Chol/phosphatidylcholine membranes where the Chol content was increased from 0 to 75 mol%, relevant to eye lens membranes. The surface roughness of the membrane decreases with an increase of Chol content until it reaches 60 mol%, and roughness increases with …
Tip-Enhanced Stimulated Raman Scattering With Ultra-High-Aspect-Ratio Tips And Confocal Polarization Raman Spectroscopy For Evaluation Of Sidewalls In Type Ii Superlattices Fpas, D. A. Tenne
Physics Faculty Publications and Presentations
Actoprobe team had developed custom Tip Enhancement Raman Spectroscopy System (TERS) with specially developed Ultra High Aspect Ratio probes for AFM and TERS measurements for small pixel infrared FPA sidewall characterization. Using this system, we report on stimulated Raman scattering observed in a standard tip-enhanced Raman spectroscopy (TERS) experiment on GaSb materials excited by 637-nm pump laser light. We explain our results by TERS-inherent mechanisms of enormous local field enhancement and by the special design and geometry of the ultra- high-aspect-ratio tips that enabled conditions for stimulated Raman scattering in the sample with greatly enhanced resonance Raman gain when aided …
Confocal Raman Spectroscopy And Afm For Evaluation Of Sidewalls In Type Ii Superlattice Fpas, D. A. Tenne
Confocal Raman Spectroscopy And Afm For Evaluation Of Sidewalls In Type Ii Superlattice Fpas, D. A. Tenne
Physics Faculty Publications and Presentations
We propose to utilize confocal Raman spectroscopy combined with high resolution atomic force microscopy (AFM) for nondestructive characterisation of the sidewalls of etched and passivated small pixel (24 μm×24 μm) focal plane arrays (FPA) fabricated using LW/LWIR InAs/GaSb type-II strained layer superlattice (T2SL) detector material. Special high aspect ratio Si and GaAs AFM probes, with tip length of 13 μm and tip aperture less than 7°, allow characterisation of the sidewall morphology. Confocal microscopy enables imaging of the sidewall profile through optical sectioning. Raman spectra measured on etched T2SL FPA single pixels enable us to quantify the …
Imaging Stability In Force-Feedback High-Speed Atomic Force Microscopy, Byung I. Kim, Ryan Boehm
Imaging Stability In Force-Feedback High-Speed Atomic Force Microscopy, Byung I. Kim, Ryan Boehm
Physics Faculty Publications and Presentations
We studied the stability of force-feedback high-speed atomic force microscopy (HSAFM) by imaging soft, hard, and biological sample surfaces at various applied forces. The HSAFM images showed sudden topographic variations of streaky fringes with a negative applied force when collected on a soft hydrocarbon film grown on a grating sample, whereas they showed stable topographic features with positive applied forces. The instability of HSAFM images with the negative applied force was explained by the transition between contact and noncontact regimes in the force-distance curve. When the grating surface was cleaned, and thus hydrophilic by removing the hydrocarbon film, enhanced imaging …