@article{garcia_giannuzzi_stevie_strader_2022, title={Enhanced focused ion beam milling with use of nested raster patterns}, volume={40}, ISSN={["2166-2754"]}, DOI={10.1116/6.0001411}, abstractNote={The focused ion beam (FIB) instrument is designed to provide the removal of material with nanometer-scale precision. However, one often needs to remove a substantial amount of material to expose the region of interest or prepare a specimen for transmission electron microscopy analysis. The maximum current available on Ga+ FIB sources is less than 100 nA, and this is a limiting factor when removal on the millimeter scale is desired. Any improvement in the removal rate reduces the analysis time and increases the range of samples that can be analyzed. Optimization of ion beam parameters, such as dwell time and overlap, can improve material removal and reduce redeposition. Since sputtering occurs faster at an edge, the use of a nested arrangement of raster patterns to more frequently present an edge to the ion beam was able to improve the removal of material at the region of interest by over 30% in the silicon and polycrystalline copper substrates used for this study. A confocal laser scanning microscope made possible an accurate determination of the material removed.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Garcia, Roberto and Giannuzzi, Lucille A. and Stevie, Fred A. and Strader, Phillip}, year={2022}, month={Jan} }
 @article{teska_dayton_li_lamb_strader_2020, title={Damage to Common Healthcare Polymer Surfaces from UV Exposure}, volume={10}, ISSN={["1793-9852"]}, DOI={10.1142/S1793984420500014}, abstractNote={ Healthcare-associated infections are a significant concern in acute care facilities across the US. Studies have shown the importance of a hygienic patient environment in reducing the risk of such infections. This has caused an increased interest in ultraviolet (UV-C) light disinfectant technology as an adjunct technology to provide additional pathogen reduction to environmental surfaces and patient care equipment (i.e., surfaces). It is also well known that UV-C light can cause premature degradation of materials, particularly certain plastic materials. However, there is little information in the literature regarding characterizing this degradation of plastics and other materials used for surfaces in healthcare. This study aims to evaluate multiple characterization techniques and propose a systematic approach to further understand early onset degradation of plastics due to UV-C exposure. Susceptibility and modes of degradation of multiple plastic materials were compared using the techniques evaluated. Ten grades of plastic materials were exposed to UV-C light in a manner consistent with standards given in the healthcare and furniture industry to achieve disinfection. These materials were characterized for visual appearance, chemical composition, surface roughness and hardness using light microscopy, spectrophotometry, contact angle analysis, infrared spectroscopy, profilometry and nanoindentation. All characterization methods were able to identify one or more specific degradation features from UV-C exposure covering different aspects of physicochemical properties of the surfaces. However, these methods showed different sensitivity and applicability to identify the onset of surface damage. Different types of surface materials showed different susceptibility and modes to degradation upon UV-C light exposure. UV-C disinfection can cause detectable damage to various surfaces in healthcare. A characterization approach consisting of physical and chemical characterizations is proposed in quantifying surface degradation of a material from UV-C exposure to address the complexity in modes of degradation and the varied sensitivity to UV-C from different materials. Methods with high sensitivity can be used to evaluate onset of damage or early stage damage. }, number={3}, journal={NANO LIFE}, author={Teska, Peter and Dayton, Roderick and Li, Xiaobao and Lamb, Jason and Strader, Phillip}, year={2020}, month={Sep} }
 @article{strader_lee_teska_li_jones_2019, title={Approaches for Characterizing Surfaces Damaged by Disinfection in Healthcare}, volume={9}, ISSN={["1793-9852"]}, DOI={10.1142/S1793984419500028}, abstractNote={ Healthcare-Associated Infections (HAIs) are a significant cause of morbidity and mortality and occur in many healthcare facilities including hospitals, surgery centers and long-term care facilities. It is well known that some pathogens can persist on healthcare surfaces for weeks to months and spread readily to new surfaces. It is current practice to disinfect or clean surfaces routinely in order to reduce the risk of HAIs. However, routine cleaning can damage the surface chemically or mechanically, which may actually increase the surface contamination. Fundamental knowledge is therefore needed to understand the influence of cleaning and disinfection on healthcare surfaces in order to mitigate pathogen persistence. In this study, materials and objects found in healthcare facilities were selected and exposed to disinfection procedures including wiping and soaking with readily available chemical disinfectants. A variety of chemical disinfectants were selected which contain hydrogen peroxide, quaternary ammonia, and chlorine, respectively. Optical microscopy, contact angle measurement, atomic force microscopy (AFM), Fourier Transform Infrared (FTIR) spectroscopy and nanoindentation are used to analyze surface characteristics before and after disinfection in order to study the effect of disinfection on material properties. Disinfection procedures are found to cause changes to surface properties of materials and objects which can be detected and observed or quantified by the approaches used in this study. The methods should become regular practice in the studies of healthcare surfaces and their role in HAIs. Each method in this study may not be reliably applied to every object or disinfection scenario. Sample geometry and features may influence response during measurement and affect results. The combination of the approaches is able to sufficiently characterize chemical, mechanical, and topological changes to the surface. }, number={4}, journal={NANO LIFE}, author={Strader, Phillip and Lee, Younghwan and Teska, Peter and Li, Xiaobao and Jones, Jacob L.}, year={2019}, month={Dec} }