Adventitious Contamination Research Articles

2M NaCl by XPS using monochromatic Al K α x rays

Cryo-XPS enables the study of many substances that are unsuitable for standard XPS analysis, such as moderately volatile liquids, biological samples, porous materials, and polymeric materials that may outgas significantly under ultrahigh vacuum conditions. In this article, XPS spectra of a 50 μl frozen droplet of 2M sodium chloride solution (NaCl) in Millipore water purified to 18.2 MΩ cm at 25 °C were obtained using an Al Kα (1486.6 eV) source with a quartz (1010) crystal monochromator through first order diffraction and irradiating the sample at 54.7° to the surface normal. The sample was sputter cleaned using a Gas Cluster Ion Source pre-acquisition to remove the minor layer of adventitious carbon contamination on the surface. Spectra of the principal lines include Na 1s, O 1s, and Cl 2p. Spectra of O KLL, Na KLL, Cl 2s, Na 2s, Na 2p, O 2s, and valence band were also acquired.

Food process contaminants: formation, occurrence, risk assessment and mitigation strategies - a review.

Thermal treatment of food can lead to the formation of potentially harmful chemicals, known as process contaminants. These are adventitious contaminants that are formed in food during processing and preparation. Various food processing techniques, such as heating, drying, grilling, and fermentation, can generate hazardous chemicals such as acrylamide (AA), advanced glycation end products (AGEs), heterocyclic aromatic amines (HAAs), furan, polycyclic aromatic hydrocarbons (PAHs), N-nitroso compounds (NOCs), monochloropropane diols (MCPD) and their esters (MCPDE) which can be detrimental to human health. Despite efforts to prevent the formation of these compounds during processing, eliminating them is often challenging due to their unknown formation mechanisms. It is critical to identify the potential harm to human health in processed food and understand the mechanisms by which harmful compounds form during processing, as prolonged exposure to these toxic compounds can lead to health problems. Various mitigation strategies, such as the use of diverse pre- and post-processing treatments, product reformulation, additives, variable process conditions, and novel integrated processing techniques, have been proposed to control these food hazards. In this review, we summarize the formation and occurrence, the potential for harm to human health produced by process contaminants in food, and potential mitigation strategies to minimize their impact.

Differentiation of human pluripotent stem cells into insulin-producing islet-like clusters using nanofiltered cell culture medium

The challenge of using patient-specific, autologous stem cell therapies in clinical settings is the need for advanced cell processing and expansion technologies. These include decentralized, small-scale manufacturing at the point of care in hospitals. The highest risk for contamination in cell-based therapy products comes from animal- and human-derived components such as serum, blood components, and growth factors. To mitigate the risk of adventitious microorganism contamination, preventive measures like size-exclusion virus removal filtration of cell media components can be employed. This article examines the impact of nanofiltration using nanocellulose-based virus clearance filter paper on the differentiation of human pluripotent stem cells into insulin-producing pancreatic islets (SC-islets). The cells were monitored for biomarkers using flow cytometry and immunohistochemistry along the 7-stage differentiation protocol. The produced SC-islets were evaluated functionally using low and high glucose stimulation under dynamic perifusion conditions. Pluripotent stem cells grown in culture media filtered through 20 nm cut-off nanocellulose filters showed similar expression of desired biomarkers at each stage compared to the control group. At the end of stage 7, SC-islets exhibited a rounded shape and strong expression of insulin, glucagon, and somatostatin in both the control and filtered media groups. The present study demonstrates that SC-islets differentiated with nanofiltered media were functional.

Surface analysis insight note: Illustrating the effect of adventitious contamination on Pt photoemission peak intensities

Adventitious carbon contaminations are not only omnipresent and used for charge referencing of XPS spectra but also can alter the apparent presence of the element peaks that span over the large spectral window of binding energies. This Insight note describes the effect of an adventitious contamination layer on Pt and presents, in brief, the approach whereby the component spectra are derived for ion beam cleaned Pt samples that can then utilize linear mathematics to peak fit said spectra thus quantifying the amount of each component including that assigned to the contamination itself of Pt metal.

Effects of High-Energy Electron Beam Irradiation on The Structure, Composition and Morphological Properties of Graphene Nanoplatelet Films

This work demonstrated the effects of 1.2 GeV high-energy electron beam irradiation on a few-layers of graphene (FLG) and multi-layer graphene (MLG) films grown via an in-house hot wire chemical vapour deposition (HWCVD) system. The FLG and MLG films were grown on highly doped n-type c-Si (100) substrates which were pre-treated using argon plasma (50 W) for 1 min and 10 min, respectively. The as-prepared samples were then irradiated using a 1.2 GeV high-energy electron beam with a dosage of 1.2 × 109 e-/cm2 at atmospheric and room temperature ambient conditions. The effects of the irradiation-mediated defects on the carbon lattice structure of both graphene samples were validated from the decreased sp2 C=C carbon content, and the increase in the adventitious carbon contamination C-O-C content. Raman results showed an elevation of the ID/IG ratio and blue-shift of the 2D and G band peaks for both the irradiated samples, which validated the mediated defects due to the dislocation of carbon atoms in the graphene sheets. The blue-shifted of 2D and G peaks were much more significant in the MLG than FLG which may indicate a better self-reconstructing property for the MLG atomic network, compared to the FLG. The stability of the films against high-energy electron beam irradiation was validated by their conductivity and surface topography. In conclusion, HWCVD grown graphene nanoplatelet films have high potential for graphene-based high-energy charged particle detectors.

VAMAS TWA2 interlaboratory comparison: Surface analysis of TiO2 nanoparticles using ToF-SIMS

Due to the extremely high specific surface area of nanoparticles and corresponding potential for adsorption, the results of surface analysis can be highly dependent on the history of the particles, particularly regarding sample preparation and storage. The sample preparation method has, therefore, the potential to have a significant influence on the results. This report describes an interlaboratory comparison (ILC) with the aim of assessing which sample preparation methods for ToF-SIMS analysis of nanoparticles provided the most intra- and interlaboratory consistency and the least amount of sample contamination. The BAM reference material BAM-P110 (TiO2 nanoparticles with a mean Feret diameter of 19 nm) was used as a sample representing typical nanoparticles. A total of 11 participants returned ToF-SIMS data, in positive and (optionally) negative polarity, using sample preparation methods of “stick-and-go” as well as optionally “drop-dry” and “spin-coat.” The results showed that the largest sources of variation within the entire data set were caused by adventitious hydrocarbon contamination or insufficient sample coverage, with the spin-coating protocol applied in this ILC showing a tendency toward insufficient sample coverage; the sample preparation method or the participant had a lesser influence on results.

Environmental DNA as an innovative technique to identify the origins of falsified antimalarial tablets—a pilot study of the pharmabiome

Falsified medicines are a major threat to global health. Antimalarial drugs have been particularly targeted by criminals. As DNA analysis has revolutionized forensic criminology, we hypothesized that these techniques could also be used to investigate the origins of falsified medicines. Medicines may contain diverse adventitious biological contamination, and the sealed nature of blister-packages may capture and preserve genetic signals from the manufacturing processes allowing identification of production source(s). We conducted a blinded pilot study to determine if such environmental DNA (eDNA) could be detected in eleven samples of falsified and genuine artesunate antimalarial tablets, collected in SE Asia, which could be indicative of origin. Massively Parallel Sequencing (MPS) was used to characterize microbial and eukaryote diversity. Two mitochondrial DNA analysis approaches were explored to detect the presence of human DNA. Trace eDNA from these low biomass samples demonstrated sample specific signals using two target markers. Significant differences in bacterial and eukaryote DNA community structures were observed between genuine and falsified tablets and between different packaging types of falsified artesunate. Human DNA, which was indicative of likely east Asian ancestry, was found in falsified tablets. This pilot study of the ‘pharmabiome’ shows the potential of environmental DNA as a powerful forensic tool to assist with the identification of the environments, and hence location and timing, of the source and manufacture of falsified medicines, establish links between seizures and complement existing tools to build a more complete picture of criminal trade routes. The finding of human DNA in tablets raises important ethical issues that need to be addressed.

Factors affecting robustness of anion exchange chromatography: Selective retention of minute virus of mice using membrane media

Mobile and stationary phase factors were investigated in order to identify conditions for effective capture of minute virus of mice (MVM), a potential adventitious contaminant in biomanufacturing, using anion exchange membrane chromatography (AEX). The initial study was conducted for Membrane A for a range of feed conditions using bovine serum albumin (BSA) as a model protein mimicking acidic host-cell proteins (HCPs) competitive for virus binding. The effects of pH (6–8), salt concentration (0–150 mM NaCl) and level of BSA (0–10 g/L) were systematically investigated. It was found that higher BSA concentration has the most negative impact on MVM binding followed by the increased conductivity of the feed solution. The effect of pH on MVM binding is also detected but has a less impact compared to other two factors in the range of feed conditions investigated. In addition to Membrane A, three other AEX membranes (Membrane B, C and D) were investigated for MVM binding at a selected feed condition. Based on properties of the membranes investigated, it was found that ligand charge density has the most significant impact on MVM binding performance of AEX membranes from stationary phase perspective.

Suitability of NIID-MDCK cells as a substrate for cell-based influenza vaccine development from the perspective of adventitious virus susceptibility.

The practical use of cell-based seasonal influenza vaccines is currently being considered in Japan. From the perspective of adventitious virus contamination, we assessed the suitability of NIID-MDCK cells (NIID-MDCK-Cs) as a safe substrate for the isolation of influenza viruses from clinical specimens. We first established a sensitive multiplex real-time PCR system to screen for 27 respiratory viruses and used it on 34 virus samples that were isolated by passaging influenza-positive clinical specimens in NIID-MDCK-Cs. Incidentally, the limit of detection (LOD) of the system was 100 or fewer genome copies per reaction. In addition to influenza viruses, human enterovirus 68 (HEV-D68) genomes were detected in two samples after two or three passages in NIID-MDCK-Cs. To further investigate the susceptibility of NIID-MDCK-Cs to adventitious viruses, eight common respiratory viruses were subjected to passages in NIID-MDCK-Cs. The genome copy numbers of seven viruses other than parainfluenza 3 decreased below the LOD by passage 4. By passaging in NIID-MDCK-Cs, the genome numbers of the input HEV-D68, 1 × 108 copies, declined to 102 at passage 3 and to under the LOD at passage 4, whereas those of the other six viruses were under the LOD by passage 3. These results implied that during the process of isolating influenza viruses with NIID-MDCK-Cs, contaminating viruses other than parainfluenza 3 can be efficiently removed by passages in NIID-MDCK-Cs. NIID-MDCK-Cs could be a safe substrate for isolating influenza viruses that can be used to develop cell-based influenza vaccine candidate viruses.

Validation of Two Real-Time PCR Approaches for the Relative Quantitation of Pork and Horse DNA in Food Samples

Two real-time PCR methods for the relative quantitation of DNA from meat species in food samples are described: these methods are applicable for horse in processed beef meat products, and pork in raw/processed beef meat products. Test samples were prepared using raw meat admixtures or processed horse/pork in beef food products made to an industry-standard recipe. The methods were subjected to single laboratory method validation, evaluating the performance characteristics of specificity, PCR efficiency and r-squared (r2), Limit of Detection (LOD), Limit of Quantitation (LOQ), and precision and trueness. A limited UK-based inter-laboratory trial of the two methods was completed involving four participating laboratories. Full statistical analysis of the data qualified the applicability of the methods for accurate and sensitive trace-level analysis. The methods were deemed fit for purpose for reproducibly distinguishing between adventitious contamination at 0.1% (w/w), the level for further enforcement action at 1% (w/w), and a level representative of deliberate economically motivated adulteration (10% (w/w)). The data provided evidence that the precision of the two methods was applicable for qualitative and quantitative detection at topically important levels of adulteration. This work has added significant value to the current state of the art in quantitative determination of topical meat species adulteration, allowing analysts to distinguish between adventitious contamination and deliberate adulteration. The resulting methods described in this paper can easily be deployed and used by analytical laboratories for controls and due-diligence testing based on standard laboratory equipment.

Action of Bromelain and Ficin on horse anti Bothrops sp venom Antibodies

The treatment with hyperimmune sera constitute the only specific and effective therapy available against snakebite envenomation, most common in developing countries. Serum quality is an important factor on patient recovery time and in the incidence of death and permanent disability. To date, most sera consist of pepsin digested IgG antibodies harvested from hyperimmune animals. The use of animal derived enzymes, such as pepsin, to digest IgG, constitute a source of adventitious agents and contaminants, such as porcine circovirus. The present study aims to evaluate the use of the plant derived enzymes bromelain and ficin, as an alternative to pepsin. To this purpose, horse serum immunized against Bothrops venoms was purified with caprylic acid and digested with bromelain or ficin. SDS-PAGE results evidence the formation of F(ab)’2 fragments and suggest that a digestion time superior to 8 hours may be required to completely digest the antibodies with bromelain or ficin. F(ab)’2 fragments obtained by digestion with either bromelain or ficin digestion preserved the ability to recognize Bothrops sp. venom in western blotting assays. Therefore, both enzymes are suitable for use in large-scale production, minimizing contamination risks and increasing safety and efficiency of serotherapy treatments.

A quantitative detection of mung bean in chestnut paste using duplex digital PCR

Highly manufacturing process of chestnut paste leaves a considerable space for Economically Motivated Adulteration (EMA) with cheaper ingredients such as mung bean. In this paper a novel quantitative detection of mung bean in chestnut paste using duplex digital PCR was reported. Two sets of primers and probes were designed according to mung bean and chestnut specific genomic genes suitable for duplex droplet digital PCR (ddPCR) and duplex chip digital PCR (cdPCR) to set up a mass ratio quantitative detection method for mung bean, a common alternative plant-derived ingredient in chestnut paste products. The manufacturing process of chestnut paste products was considered to establish the linear relationship formula between mass ratio and gene copy number (CN) ratio of the two ingredients. The limits of quantification for gene CN concentrations (LOQcopy) of mung bean and chestnut were both 6 copies/μL, at the same time a mass ratio of mung bean in chestnut paste range from 5% to 80% was able to be quantified accurately to provide technical support for the identification of fraudulent substitution or adventitious contamination.

Proceedings of the 2019 Viral Clearance Symposium, Session 7: Cell Banks and U.S. Pharmacopeia.

Adventitious contamination of a manufacturing process is a major concern for biopharmaceutical manufacturers. This session focused on rapid detection methods for adventitious agents and mitigation methods for upstream media and feeds. In the first session, it was shown that next-generation sequencing (NGS) can be a good rapid alternative to existing methods used to detect adventitious virus contamination. The second session showed that upstream virus barrier filters can robustly remove virus from media and feeds and could be a good alternative to high-temperature short time (HTST) aimed at facility contamination risk mitigation. In the third session, testing for Mycobacterium species was requested by the Chinese health authority for cell banks. In this case, the risk of mycobacterial contamination was minimal for well-characterized cell banks, and robust downstream processes are in place to remove any potential adventitious contaminants such as viruses and bacteria; therefore, it was not needed. In the final session, a review of rapid testing methods for viral detection was discussed as well as the possibility of using these technologies to replace existing methods.

Proton Transfer on the Edge of the Salt/Cocrystal Continuum: X-Ray Photoelectron Spectroscopy of Three Isonicotinamide Salts

X-ray photoelectron spectroscopy (XPS) has emerged as a technique that allows for characterization and classification of hydrogen bonding and proton transfer interactions in organic crystal structures, in a way that is complementary to crystallography by X-ray or neutron diffraction. Here, we analyze the nitrogen 1s core-level binding energies (BEs) of isonicotinamide (IN) systems with proton transfer between donor and acceptor groups at short distances. We show how a careful calibration of the BE scale places these salt systems correctly on the edge of the so-called salt–cocrystal continuum. We show how performing a fitting analysis of the data that is consistent with elemental analysis, expected stoichiometry, and quantification of adventitious carbon contamination facilitates the determination of absolute BEs with accuracy and reproducibility within ±0.1 eV. The determined N 1s core-level BEs of the protonated IN acceptors suggest that the local geometric arrangements of the donor, acceptor, and proton can influence the N 1s core-level BE significantly.

Rare-Earth Doping Graphitic Carbon Nitride Endows Distinctive Multiple Emissions with Large Stokes Shifts

Rare-Earth Doping Graphitic Carbon Nitride Endows Distinctive Multiple Emissions with Large Stokes Shifts

Au(111) Surface Contamination in Ambient Conditions: Unravelling the Dynamics of the Work Function in Air

AbstractGold is an inert noble metal displaying superior chemical stability that renders it a suitable component for the manufacturing of electrodes for various types of devices. Despite being widely employed, the variation of gold surface properties occurring upon the material's exposure to ambient conditions have been often disregarded. While it is well‐known that the contamination of a metallic surface can have a dramatic impact on its properties, the process of contamination itself is poorly understood. Changes of the work function by fractions of an electron‐volt are commonly observed in gold surfaces that are processed at ambient laboratory conditions, but an exhaustive comprehension and control of this phenomenon are still lacking. Here, a multiscale characterization of Au(111) surfaces aiming to unravel the surface dynamics underlying the air contamination is presented. The visualization of the adventitious carbon contamination on Au(111) surface by atomic force microscopy is key to rationalize the mechanisms of surface reorganization ruling the change of Au work function between 5.25 and 4.75 eV by solely changing the storage conditions. Such a huge variation must be taken into account when optimizing the Au surface for both controlling its fundamental surface and interfacial physical processes, as well as its functional applications.

Review: High temperature short time treatment of cell culture media and feed solutions to mitigate adventitious viral contamination in the biopharmaceutical industry.

Events of viral contaminations occurring during the production of biopharmaceuticals have been publicly reported by the biopharmaceutical industry. Upstream raw materials were often identified as the potential source of contamination. Viral contamination risk can be mitigated by inactivating or eliminating potential viruses of cell culture media and feed solutions. Different methods can be used alone or in combination on raw materials, cell culture media, or feed solutions such as viral inactivation technologies consisting mainly of high temperature short time, ultraviolet irradiation, and gamma radiation technologies or such as viral removal technology for instance nanofiltration. The aim of this review is to present the principle, the advantages, and the challenges of high temperature short time (HTST) technology. Here, we reviewed effectiveness of HTST treatment and its impact on media (filterability of media, degradation of components), on process performance (cell growth, cell metabolism, productivity), and product quality based on knowledge shared in the literature.

Bioproduction of Pharmaceuticalsbioprocess and the Developing World

Industrial animal cell culture is used to make many life-saving biopharmaceutical proteins, vaccines and cell therapies. Contamination of an industrial animal cell culture with a microorganism, such as a bacteria or virus, may occur through many means, for example, human error, inadequate aseptic protocols within biosafety level 2 (BSL-2) cabinets, failure of a processing step such as steam sterilization, loss of equipment integrity such as a crack in a disposable bioreactor, and/or introduction of a new adventitious agent not susceptible to current removal or inactivation procedures.The term microorganism is synonymous with the common term microbe (adjective microbial). In response to such contamination crises, many firms simultaneously implemented a large number of changes, in emergency mode, without first identifying the source of the problem or thus understanding the likely effectiveness of any given change. Over time, one key change or two typically solved the problem. Sometimes the source of the problem, as well as the key change(s) that actually solved the problem, were identified. Other times, no such clear identifications were made. In nearly all cases, the whole slew of changes were carried forward, even though some were likely ineffective, as well as a waste of time, money and focus. Yet many people in developing countries who could benefit from pharmaceuticals do not receive them. The failure of antiretroviral therapy to reach more than a tiny fraction of people with AIDS in developing countries has attracted widespread publicity, but even medicines that are far cheaper and easier to deliver are not reaching many of the people who need them. More than a quarter of children worldwide and over half of children in some countries do not receive the vaccines that are part of WHO’s Expanded Program on Immunization, although these cost only pennies per dose and require no diagnosis. Three million lives are lost annually as a result (World Bank, 2001a). Only a small fraction of children in poor countries receive the newer hepatitis B and Haemophilus influenzae b (Hib) vaccines, which cost a dollar or two per dose. One in four people worldwide suffer from intestinal worms, although treatments only need to be taken once or twice per year, have virtually no side effects, and cost less than a dollar per year. When asked which viral barriers proved impractical, company representatives had mixed responses. Filtration was characterized by some as expensive, having poor flux properties, or not suitable for use with bulk medium as some important media components were filtered out. Conversely, many interviewees stated that filtration was quite practical for small volumes, including heat-sensitive supplements, as well as hydrophobic additions. While certain respondents described HTST as quite practical and cost effective, others described it as ineffective due to cost, the large space it takes in the plant, and incompatibility with serum and hydrolysed. Since the first public disclosure of a large-scale adventitious agent contamination by Genentech, the topic of viral barriers for upstream processes has become more mainstream. However, while many mid-size or large companies have investigated the implementation of barriers and their associated challenges, some companies remain uncertain about the difficulties they may face if they would like to implement a barrier in upstream cell culture processes.

Ultraviolet Light Treatment of Titanium Enhances Attachment, Adhesion, and Retention of Human Oral Epithelial Cells via Decarbonization.

Early establishment of soft-tissue adhesion and seal at the transmucosal and transcutaneous surface of implants is crucial to prevent infection and ensure the long-term stability and function of implants. Herein, we tested the hypothesis that treatment of titanium with ultraviolet (UV) light would enhance its interaction with epithelial cells. X-ray spectroscopy showed that UV treatment significantly reduced the atomic percentage of surface carbon on titanium from 46.1% to 28.6%. Peak fitting analysis revealed that, among the known adventitious carbon contaminants, C–C and C=O groups were significantly reduced after UV treatment, while other groups were increased or unchanged in percentage. UV-treated titanium attracted higher numbers of human epithelial cells than untreated titanium and allowed more rapid cell spread. Hemi-desmosome-related molecules, integrin β4 and laminin-5, were upregulated at the gene and protein levels in the cells on UV-treated surfaces. The result of the detachment test revealed twice as many cells remaining adherent on UV-treated than untreated titanium. The enhanced cellular affinity of UV-treated titanium was equivalent to laminin-5 coating of titanium. These data indicated that UV treatment of titanium enhanced the attachment, adhesion, and retention of human epithelial cells associated with disproportional removal of adventitious carbon contamination, providing a new strategy to improve soft-tissue integration with implant devices.

Cleaning and Passivation of Copper Surface Using N2H4, and Self-Assembled Monolayers for Area-Selective Atomic Layer Deposition (AS-ALD) Applications

Copper is widely used in the semiconductor industry as interconnects due to its low resistivity, high resistance to electromigration, low temperature coefficient of resistance, and good thermal stability (1). As advanced nanoelectronics has moved towards the sub-5 nm node technology and beyond, the back-end of line interconnects process is scaled down to smaller pitch sizes with a lot of challenges (2,3). Recently, area-selective atomic layer deposition (AS-ALD) by locally passivating the surface has garnered attention as it can lead to a paradigm shift from today’s top-down VLSI fabrication by not only reducing the number of processing steps but also by alleviating key challenges associated with lithography and layer alignment at the sub-5 nm node (4). However, there are still several challenging factors to implement them in the process node successfully. Despite the enormous scientific effort in recent years, lack of surface science during cleaning and passivation of Cu surfaces impede the development of AS-ALD. Specifically, the initial surface condition of Cu films can affect not only a cleaning surface (i.e., adventitious contaminants and CuxO) but also further passivation process using a self-assembled monolayer (SAMs). Recently, the reduction of the Cu surface using vapor-phase N2H4 has been reported due to its higher reduction capability (4,5).Herein, the effect of the initial surface condition of Cu samples on both cleaning and passivation of the surfaces was investigated. Electroplated Cu films were pretreated using anhydrous N2H4 for vapor phase surface cleaning. Reflectance absorption infrared spectroscopy (RAIRS) with ALD capability was employed to elucidate the surface chemistry. During surface cleaning, N2H4 reduces the surface oxide (Cu2O) to metallic copper as well as remove adventitious surface contaminants (e.g., –CHx, –CO3, and –OH). In the case of cleaning with CH3COOH, the Cu surface reduces the surface oxide (Cu2O) to metallic copper, importantly the copper acetate which might be the intermediate material was formed after cleaning. After pretreatment, each Cu sample was immersed into 1 mM octadecanethiols (ODTs) in ethanol for 20 hours, then ALD of AlOx using TMA and H2O was performed at 120 oC. The N2H4-treated Cu sample shows better physical and chemical stability during ALD process, resulting in good selectivity compared to the SAMs on the as-is Cu. The detailed experimental results will be presented.This work is supported by Rasirc Inc. by providing the anhydrous N2H4. This work was also partly supported by the Fostering Global Talents for Innovative Growth Program (No. P0008750) through KIAT and MOTIE. J. Ahn and J. Kim also acknowledge partial financial supports by Brain Pool Program through National Research Foundation by the Ministry of Science and ICT in Korea (Grant #: 2019H1D3A2A01101691). R. P. Chaukulkar, N. F. W. Thissen, V. R. Rai, and S. Agarwal, J. Vac. Sci. Technol. A, 32, 01A108 (2014).L. F. Pena, J. F. Veyan, M. A. Todd, A. Derecskei-Kovacs, and Y. J. Chabal, ACS Appl. Mater. Interfaces, 10, 38610–38620 (2018).M. He et al., J. Electrochem. Soc., 160, D3040–D3044 (2013).D. M. Littrell, D. H. Bowers, and B. J. Tatarchuk, J. Chem. Soc. Faraday Trans. 1 Phys. Chem. Condens. Phases, 83, 3271–3282 (1987).S. M. Hwang et al., ECS Trans., 92, 265–271 (2019). Figure 1