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Palladium is the most prominent material in both scientific and industrial research on gas storage, purification, detection, and catalysis due to its unique properties as a catalyst and hydrogen absorber. Advancing the plasmonic optical phenomena of palladium reacting with hydrogen, transduction of the gas-matter reaction into light-matter interaction is attempted to visualize the dynamic surface chemistry and reaction behaviors. The simple geometry of the metal-dielectric-metal structure, Fabry-Perot etalon, is employed for a colorimetric reactor, to display the catalytic reaction of the exposed gas via water-film/bubble formation at the dielectric/palladium interface. The adsorption/desorption behavior and catalytic reaction of hydrogen and oxygen on the palladium surface display highly repeatable and dramatic color changes based on two distinct water formation trends: the foggy effect by water bubbles and the whiteout effect by water film formation. Simulations and experiments demonstrate the robustness of the proposed Fabry-Perot etalon as an excellent platform for monitoring the opto-physical phenomena driven by heterogeneous catalysis.

A photoreceptor on the retina acts as an optical waveguide to transfer an individual photonic signal to the cell inside, which is determined by the refractive index of internal materials. Under the photoactivation of photoreceptors making conformational and chemical variation in a visual cell, the optical signal modulation is demonstrated using an artificial photoreceptor-based waveguide with a controlling beam refraction. Two types of nanodiscs are made of human photoreceptor proteins, short-wavelength-sensitive opsin and rhodopsin, with spectral sensitivity. The refractive index and nonlinear features of those two photosensitive nanodiscs are investigated as fundamental properties. The photonanodiscs are photoactivated in such a way that allow refractive index tuning over 0.18 according to the biological function of the respective proteins with color-dependent response.

Topography measurement is essential for surface characterization, semiconductor metrology, and inspection applications. To date, performing high-throughput and accurate topography remains challenging due to the trade-off between field-of-view (FOV) and spatial resolution. Here we demonstrate a novel topography technique based on the reflection-mode Fourier ptychographic microscopy, termed Fourier ptychograhpic topography (FPT). We show that FPT provides both a wide FOV and high resolution, and achieves nanoscale height reconstruction accuracy. Our FPT prototype is based on a custom-built computational microscope consisting of programmable brightfield and darkfield LED arrays. The topography reconstruction is performed by a sequential Gauss-Newton-based Fourier ptychographic phase retrieval algorithm augmented with total variation regularization. We achieve a synthetic numerical aperture (NA) of 0.84 and a diffraction-limited resolution of 750 nm, increasing the native objective NA (0.28) by 3×, across a 1.2 × 1.2 mm2 FOV. We experimentally demonstrate the FPT on a variety of reflective samples with different patterned structures. The reconstructed resolution is validated on both amplitude and phase resolution test features. The accuracy of the reconstructed surface profile is benchmarked against high-resolution optical profilometry measurements. In addition, we show that the FPT provides robust surface profile reconstructions even on complex patterns with fine features that cannot be reliably measured by the standard optical profilometer. The spatial and temporal noise of our FPT system is characterized to be 0.529 nm and 0.027 nm, respectively.

Introduction The majority of radiocontrast media (RCM) reactions are from direct mast cell degeneration,[1] but there are some patients with recurrent reactions despite standard premedication who may have immediate hypersensitivity reactions[1] (IHR). Although some have found skin testing a helpful tool,[2] consensus on the best method of diagnosis and treatment is lacking. Case Description The patient is a 73-year-old Caucasian female with history of angioedema and urticaria after RCM administration on three separate occasions, despite premedication[3] with the last two exposures, history of asthma, and bicuspid aortic valve status post replacement in 2016. She presented with dyspnea and chest discomfort, diagnosed with severe prosthetic stenosis, and TAVR was recommended. Due to need for cardiac intervention with RCM, the patient underwent skin prick testing followed by intradermal testing with Iodixanol, resulting positive. Therefore, an IgE-mediated IHR to contrast dye was deduced and the patient received a desensitization protocol[4] in addition to a stronger premedication regimen[4] prior to her cardiac intervention. This was successful in preventing angioedema or urticaria, with only mild pruritus and erythema on her extremities, which resolved within 24 hours. Discussion With at least seventy million patients exposed to RCM yearly,[5] Allergist face a growing need for an efficient IHR evaluation protocol. Risk factors for recurrent reaction currently include prior severe allergic reaction to any substance, drug allergies, chronic oral glucocorticoid use, and allergy to four or more allergens.[6] Without all variables for IHR in RCM known, there remains much ambiguity in evaluation strategy, with further research required.