Ground 304 stainless steel (SS) samples were exposed to sea salt particles at 35 °C and two relative humidity (RH) levels for durations ranging from 1 week to 2 years. For all exposure times, pit number density and total pit volume at 40% RH were observed to be considerably greater than those at 76% RH. Statistical analysis of distributions of pit populations for both RH conditions showed that pit number density and total pit volume increased rapidly at first but slowed as exposure time increased. Cross-hatched features were observed in the 40% RH pits while ellipsoidal, faceted pits were observed at 76% RH. Optical profilometry indicated that most pits were not hemispherical. X-ray tomography provided evidence of undercutting and fissures. Piecewise curve fitting modeled the 40% RH data closely, predicting that corrosion damage would eventually plateau. However, a similar treatment of the 76% RH data suggested that corrosion damage would continuously increase, which implied that the piecewise power-law fit was limited in its ability to model atmospheric corrosion generally. Based on these observations, the operative mechanisms determining long-term corrosion behavior were hypothesized to be different depending on the RH of exposure.

Most research aimed at measuring biomarkers on the skin is only concerned with sensing chemicals in sweat using electrical signals, but these methods are not truly non-invasive nor non-intrusive because they require substantial amounts of sweat to get a reading. This project aims to create a truly non-invasive wearable sensor that continuously detects the gaseous acetone (a biomarker related to metabolic disorders) that ambiently comes out of the skin. Composite films of polyaniline and cellulose acetate, exhibiting chemo-mechanical actuation upon exposure to gaseous acetone, were tested in the headspaces above multiple solutions containing acetone, ethanol, and water to gauge response sensitivity, selectivity, and repeatability. The bending of the films in response to exposures to these environments was tracked by an automatic video processing code, which was found to out-perform an off-the-shelf deep neural network-based tracker. Using principal component analysis, we showed that the film bending is low dimensional with over 90% of the shape changes being captured with just two parameters. We constructed forward models to predict shape changes from the known exposure history and found that a linear model can explain 40% of the observed variance in film tip angle changes. We constructed inverse models, going from third order fits of shape changes to acetone concentrations where about 45% of the acetone variation and about 30% of ethanol variation are captured by linear models, and non-linear models did not perform substantially better. This suggests there is sufficient sensitivity and inherent selectivity of the films. These models, however, provide evidence for substantial hysteretic or long-time-scale responses of the PANI films, seemingly due to the presence of water. Further experiments will allow more accurate discrimination of unknown exposure environments. Nevertheless, the sensor will operate with high selectivity in low sweat body locations, like behind the ear or on the nails.

This document summarizes key research directions as they emerged during the proceedings of the Inaugural Orton Workshop that aimed to define scientific areas of current interest to the ceramics community around the theme of: “High Temperature Ceramics and Composites for Extreme Environments.” The topic was selected due to the timely interest in such materials to meet the needs of hypersonic aviation and space exploration and habitation. Experts from funding agencies supporting ceramics research, thought‐leaders from academia with expertise spanning materials processing, characterization, and modeling, as well as research and development leaders from key (aviation‐related) industries, gathered to evaluate the state‐of‐the‐art in this field and to address key questions with the intent of accelerating research and development efforts on all fronts. Highlights of the work presented and of the discussion and brainstorming sessions are provided here. It was the purpose of the organizers (The Orton Ceramic Foundation and the Orton Chair in Ceramic Engineering at OSU) to establish this event as a service to the Ceramics community in the spirit the founder of the field of Ceramic Engineering, Dr. Edward Orton Jr.

This paper presents sensor nanotechnologies that can be used for the skin-based gas “smelling” of disease. Skin testing may provide rapid and reliable results, using specific “fingerprints” or unique patterns for a variety of diseases and conditions. These can include metabolic diseases, such as diabetes and cholesterol-induced heart disease; neurological diseases, such as Alzheimer’s and Parkinson’s; quality of life conditions, such as obesity and sleep apnea; pulmonary diseases, such as cystic fibrosis, asthma, and chronic obstructive pulmonary disease; gastrointestinal tract diseases, such as irritable bowel syndrome and colitis; cancers, such as breast, lung, pancreatic, and colon cancers; infectious diseases, such as the flu and COVID-19; as well as diseases commonly found in ICU patients, such as urinary tract infections, pneumonia, and infections of the blood stream. Focusing on the most common gaseous biomarkers in breath and skin, which is nitric oxide and carbon monoxide, and certain abundant volatile organic compounds (acetone, isoprene, ammonia, alcohols, sulfides), it is argued here that effective discrimination between the diseases mentioned above is possible, by capturing the relative sensor output signals from the detection of each of these biomarkers and identifying the distinct breath print for each disease.

The Chevrel phase compounds Cu4Mo6S8, Ni2Mo6S8, and Fe2Mo6S8, synthesized by self-propagating high temperature synthesis, were evaluated as photocatalysts for visible light photocatalytic desulfurization. Investigations began with reflectance measurements from which absorbance spectra were calculated using the Kubelka-Munk transformation. The absorbance data was then used to create Tauc plots to find the direct and indirect bandgaps of the Chevrel phase compounds. Bandgaps were found to be no more than the 1.74 eV for Ni2Mo6S8, so it was selected for further study because this bandgap suggests it will use the sun's emission spectrum better than the other materials studied here. Photocatalytic desulfurization experiments studied the concentration of thiophene mixed into n-octane with and without exposure to Ni2Mo6S8 with and without light exposure because of the relative difficulty of removing thiophenes from liquid fossil fuels by the industry standard hydrodesulfurization process. Ultraviolet-visible spectroscopy was used to analyze chemical changes in the thiophene-octane solution. Spectroscopic results demonstrate that the thiophene was effectively removed by exposure to Ni2Mo6S8 and visible light together but not by exposure to Ni2Mo6S8 or visible light alone. Multiple tests with the same Ni2Mo6S8 sample demonstrate that the material is reusable as a catalyst for photocatalytic desulfurization. The proposed mechanism results in the release of SOx species, which may be controlled and captured if separated from fossil fuels in bulk during industrial processing in contrast to their uncontrolled release as vehicle fuel exhaust. Controlled generation and collection of these species can allow for further processing into elemental sulfur in the same way that H2S released by standard hydrodesulfurization is processed into elemental S.