Dynamic swatch testing of liquid aerosols in a laboratory-sized recirculating wind tunnel.

Chemical warfare agents (CWAs) pose a threat as gaseous substances and as liquid aerosols, necessitating chemical warfare-protective clothing for soldiers. The paramount consideration lies in the effectiveness of the clothing as a barrier against the pertinent CWAs. This paper presents a dynamic swatch test method aimed at evaluating the performance of such clothing against liquid-phase aerosol penetration. Central to the methodology is a specialized test cell designed to rotate to the left and right, integrated within a laboratory wind tunnel, replicating mission-relevant conditions with varying wind speeds. Utilizing di(2-ethylhexyl) sebacate particles as liquid aerosols, tests were conducted at wind speeds of 1.0, 3.0, and 5.0 m/s. Penetration assessment relied on analyzing particle counts downstream and upstream of the fabric, with preliminary studies showing that higher wind speeds and fabric air permeabilities increase penetration at an equivalent face velocity of 5.0 cm/s. Interestingly, penetration decreased when fabric samples were subjected to rotation. The system and methodology devised demonstrated consistent and repeatable results, offering valuable insights into optimizing the effectiveness of chemical warfare-protective clothing. This research contributes to advancing methodologies for testing protective clothing, crucial for ensuring the safety of military personnel in hazardous environments.

Bayesian predictive modeling for gas purification using breakthrough curves.

This study proposes a predictive model for assessing adsorber performance in gas purification processes, specifically targeting the removal of chemical warfare agents (CWAs) using breakthrough curve analysis. Conventional parameter estimation methods, such as Brunauer-Emmett-Teller analysis, encounter challenges due to the limited availability of kinetic and equilibrium data for CWAs. To overcome these challenges, we implement a Bayesian parametric inference method, facilitating direct parameter estimation from breakthrough curves. The model's efficacy is confirmed by applying it to H2S purification in a fixed-bed setup, where predicted breakthrough curves aligned closely with previous experimental and numerical studies. Furthermore, the model is applied to sarin with ASZM-TEDA carbon, estimating key parameters that could not be assessed through conventional experimental techniques. The reconstructed breakthrough curves closely match actual measurements, highlighting the model's accuracy and robustness. This study not only enhances filter performance prediction for CWAs but also offers a streamlined approach for evaluating gas purification technologies under limited experimental data conditions.

Ultraviolet Light-Assisted Decontamination of Chemical Warfare Agent Simulant 2-Chloroethyl Phenyl Sulfide on Metal-Loaded TiO2 /Ti Surfaces.

The application of ultraviolet (UV) light for the decontamination of chemical warfare agents (CWAs) has gained recognition as an effective method, especially for treating hard-to-reach areas where wet chemical methods are impractical. In this study, TiO2 /Ti was employed as a model catalyst, which was contaminated with 2-chloroethyl phenyl sulfide (CEPS), and subjected to photocatalytic decontamination using both UVB and UVC light. Additionally, photocatalytic decontamination efficiency by introducing Au, Pt, and Cu onto the TiO2 /Ti surface was explored. During the photodecomposition process under UVC light, at least eight distinct secondary byproducts were identified. It was observed that the introduction of overlayer metals did not significantly enhance the photodecomposition under UVC light instead overlaid Au exhibited substantially improved activity under UVB light. Whereas, photodecomposition process under UVB light, only five secondary products were detected, including novel compounds with sulfoxide and sulfone functional groups. This novel study offers valuable insights into the generation of secondary products and sheds light on the roles of overlayer metals and photon wavelength in the photodecontamination process of CWA.

ZIF-8/Graphene Oxide Hybrid Membranes as Breathable and Protective Barriers against Chemical Warfare Agents.

Personal protective equipment against chemical warfare agents and other toxic chemicals must be protective, be breathable, and have a low thermal burden. Selectively permeable membranes are promising candidates for such equipment. In this study, a hybrid membrane consisting of a continuous and thin zeolitic imidazolate framework (ZIF)-8 layer on an oxygen-rich small-flake graphene oxide layer was produced using a simple and scalable synthesis method. The small intrinsic pores of ZIF-8 allow it to selectively separate chemicals via size exclusion while permitting water vapor to permeate out. The ZIF-8/graphene oxide membrane had high selectivity for the penetration of water vapor over nerve agent simulants (ratio of dimethyl methylphosphonate to water vapor transmittance rates of ∼312) with a high water vapor transmittance rate of 3000 g m-2 day-1. This protective barrier layer is a promising material for next-generation protective clothing with enhanced comfort and operability.

Elimination of A-234 from the environment: Effect of different decontaminants.

With the fact that there are Novichoks in the list of toxic chemicals by the Chemical Weapons Convention parties, it is necessary to develop methods of effective neutralization of the agents as well as for other organophosphorus toxic substances. However, experimental studies on their persistence in the environment and effective decontamination measures remain scarce. Therefore, here, we investigated the persistence behavior and decontamination methods of A-234 (ethyl N-[1-(diethylamino)ethylidene]phosphoramidofluoridate), a Novichok series, A-type nerve agent to assess its potential risk to the environment. Different analytical methods were implemented, including 31P solid-state magic angle spinning nuclear magnetic resonance (NMR), liquid 31P NMR, gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry, and vapor-emission screening using a microchamber/thermal extractor with GC-MS. Our results showed that A-234 is extremely stable in sand and poses a long-lasting risk to the environment even when released in trace quantities. Moreover, the agent is not easily decomposed by water, dichloroisocyanuric acid sodium salt, sodium persulfate, and chlorine-based water-soluble decontaminants. However, it is efficiently decontaminated by Oxone® monopersulfate, calcium hypochlorite, KOH, NaOH, and HCl within 30 min. Our findings provide valuable insights for eliminating the highly dangerous Novichok agents from the environment.

Ultralight and Ultrathin Electrospun Membranes with Enhanced Air Permeability for Chemical and Biological Protection.

With the growing interest in chemical and biological warfare agents (CWAs/BWAs), the focus has shifted toward aerosol protection using protective clothing. However, compared to air-permeable membranes, those with water vapor permeability have been investigated more extensively. Filtering membranes without air permeability have limited practical usage in personal protective suits and masks. In this study, polyacrylonitrile membranes with tightly attached activated carbon and doped copper(II) oxide were prepared via electrospinning. The nanofibers with uniformly controlled diameters and smooth morphologies enable water/air breathability and protection against aerosol (100 nm polystyrene nanobeads similar to SARS-CoV-2) penetration. The uniformly distributed and tightly attached activated carbon and doped copper(II) oxide particles enhance the sorptive performance of the membranes by blocking gaseous CWAs, including soman, nerve chemical agents, and BWAs. Such dual-purpose membranes can be implemented in protective equipment owing to their high performance and easy processing.

Effective inactivation of Bacillus atrophaeus spores and Escherichia coli on disposable face masks using ultraviolet laser irradiation.

Due to the widespread emergence of COVID-19, face masks have become a common tool for reducing transmission risk between people, increasing the need for sterilization methods against mask-contaminated microorganisms. In this study, we measured the efficacy of ultraviolet (UV) laser irradiation (266 nm) as a sterilization technique against Bacillus atrophaeus spores and Escherichia coli on three different types of face mask. The UV laser source demonstrated high penetration of inner mask layers, inactivating microorganisms in a short time while maintaining the particle filtration efficiency of the masks. This study demonstrates that UV laser irradiation is an efficient sterilization method for removing pathogens from face masks.

Short-chain fluorocarbon-based polymeric coating with excellent nonwetting ability against chemical warfare agents.

The ongoing concerns and regulations on long-chain fluorinated compounds (C8 or higher) for nonwetting coatings have driven the market to search for sustainable alternative chemistries. In this study, a copolymeric coating containing short-chain fluorinated groups was synthesized to achieve excellent nonwetting ability against hazardous chemical warfare agents (CWAs). A copolymer of 1H,1H,2H,2H-perfluorooctyl methacrylate (PFOMA) and ethylene glycol dimethacrylate (EGDMA, crosslinker) was directly coated onto a textile fabric via initiated chemical vapor deposition. The p(PFOMA-co-EGDMA) coating shows a rough-textured morphology with a bumpy, raspberry-like structure leading to high contact angles (θ water > 150° and θ dodecane = 113.8°) and a small water shedding angle (<5°). Moreover, the p(PFOMA-co-EGDMA) coating was further analysed for application in military fabrics: air permeability, tensile strength, and safety against toxic perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Outstanding nonwetting was noticeably achieved against different CWAs, including bis(2-chloroethyl)sulfide (HD), pinacolyl methylfluorophosphonate (GD), and O-ethyl S-(2-diisopropylaminoethyl)methylphosphonothioate (VX) (θ HD = 119.1°, θ GD = 117.0°, and θ VX = 104.1°). The coating retained its nano-structuration and nonwetting ability for water and n-dodecane despite being subjected to 250 cycles of Martindale abrasion and harsh chemicals (NaOH and HCl). The robustness and scalable straightforward preparation route of the coating make it an ideal approach for designing durable next-generation CWA nonwetting coatings for fabrics with favorable health and environmental properties.

Blocking chemical warfare agent simulants by graphene oxide/polymer multilayer membrane based on hydrogen bonding and size sieving effect.

Chemical warfare agents (CWAs) are toxic materials that cause death by contact with the skin or by respiration. Although studies on detoxification of CWAs have been intensively conducted, studies that block CWAs permeation are rare. In this study, for blocking CWAs, a multilayer thin film composed of linear polyethylenimine (LPEI) and graphene oxide (GO) is simply prepared through a spray-assisted Layer-by-Layer (LbL) assembly process. LPEI could change its morphology dependent on pH, which is known as a representative hydrogen donor and acceptor. By controlling the shape of the polymer chain, a heterogenous film could have a loose or dense inner structure. CWAs mainly move through diffusion and have hydrogen bonding sites. Therefore, the heterogeneous film can limit CWAs movement based on controlling pathways and hydrogen bonds within the film. The protective effect of this membrane is investigated using dimethyl methylphosphonate (DMMP), a nerve gas simulant. DMMP vapor transmittance rate (DVTR) and N2 permeance of LPEI/GO are 67.91 g/m2 day and 34,293.04 GPU. It means that the protection efficiency is 72.65%. Although this membrane has a thin thickness (100 nm), it shows a high protective effect with good breathability. And water/DMMP selectivity of the membrane is 66.63. Since this multilayer membrane shows efficient protection performance with a simple preparation method, it has a high potential for applications such as protective suits and masks.

Sterilization effects of UV laser irradiation on Bacillus atrophaeus spore viability, structure, and proteins.

Bacillus spores are highly resistant to toxic chemicals and extreme environments. Because some Bacillus species threaten public health, spore inactivation techniques have been intensively investigated. We exposed Bacillus atrophaeus spores to a 266 nm Nd:YVO4 laser at a laser power of 1 W and various numbers of scans. As a result, the UV laser reduced the viability of Bacillus atrophaeus spores. Although the outer coat of spores remained intact after UV laser irradiation of 720 scans, damage inside the spores was observed. Spore proteins were identified by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry during the course of UV laser irradiation. Photochemical and photothermal processes are believed to be involved in the UV laser sterilization of Bacillus spores. Our findings suggest that a UV laser is capable of sterilizing Bacillus atrophaeus spores.

UiO-66-NH2 and Zeolite-Templated Carbon Composites for the Degradation and Adsorption of Nerve Agents.

Composites of metal-organic frameworks and carbon materials have been suggested to be effective materials for the decomposition of chemical warfare agents. In this study, we synthesized UiO-66-NH2/zeolite-templated carbon (ZTC) composites for the adsorption and decomposition of the nerve agents sarin and soman. UiO-66-NH2/ZTC composites with good dispersion were prepared via a solvothermal method. Characterization studies showed that the composites had higher specific surface areas than pristine UiO-66-NH2, with broad pore size distributions centered at 1-2 nm. Owing to their porous nature, the UiO-66-NH2/ZTC composites could adsorb more water at 80% relative humidity. Among the UiO-66-NH2/ZTC composites, U0.8Z0.2 showed the best degradation performance. Characterization and gas adsorption studies revealed that beta-ZTC in U0.8Z0.2 provided additional adsorption and degradation sites for nerve agents. Among the investigated materials, including the pristine materials, U0.8Z0.2 also exhibited the best protection performance against the nerve agents. These results demonstrate that U0.8Z0.2 has the optimal composition for exploiting the degradation performance of pristine UiO-66-NH2 and the adsorption performance of pristine beta-ZTC.

Ag-exchanged mesoporous chromium terephthalate with sulfonate for removing radioactive methyl iodide at extremely low concentrations in humid environments.

The development of efficient adsorbents to remove radioactive methyl iodide (CH3I) in humid environments is crucial for air purification after pollution by nuclear power plant waste. In this work, we successfully prepared a post-synthetic covalent modified MIL-101 with a sulfonate group followed by the ion-exchange of Ag (I), which is well characterized by diffuse reflectance FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and the hydrophobic index (HI). After modification of the MOFs, we applied functionalized MIL-101 obtained by either one-pot synthesis (MIL-101-SO3Ag) or a post-synthetic modification process (MIL-101-RSO3Ag, R = NH(CH2)3) to remove the CH3I at an extremely low concentration (0.31 ppm) in an environment with very high relative humidity (RH 95%). Enhanced hydrophobicity of the surface-modified MIL-101 was evaluated by examining the HI with the competitive adsorption of water and cyclohexane vapor, with a high surface area maintained, as confirmed by Ar physisorption. Interestingly, the post-synthetically modified MIL-101-RSO3Ag showed exceptional adsorption performance as determined by its decontamination factor (DF = 195,350) at 303 K and RH 95%. This performance was in comparison to Ag (I)-exchanged 13X zeolite and MIL-101-SO3Ag, which include much higher amounts of Ag. Furthermore, MIL-101-RSO3Ag retained ~94-100% of its fresh adsorbent performance during five cycle repetitions.

Micro/Nanostructured Coating for Cotton Textiles That Repel Oil, Water, and Chemical Warfare Agents.

Using a lotus leaf as our model, we fabricated an extremely low surface energy micro/nanostructured coating for textiles that repel oil, water, and chemical warfare agents (CWAs) using a simple process that is suitable for large scale production. This coating, called "OmniBlock", consisted of approximately 200-nm silica nanoparticles, tetraethylorthosilicate, 3-glycidoxypropyl trimethoxysilane, and a perfluorooctanoic acid-free fluoropolymer (Fluorolink S10) that was cross-linked between Si-O-Si groups via a sol-gel process. The perfluorooctanoic acid-free fluoropolymer-coated silica nanoparticles were simply applied to the surface of a cotton fabric by a dip-dry-cure process, forming dense, continuous, and uniform layers of OmniBlock coating. OmniBlock modified the surface of the cotton fibers, creating a rough, high surface area uniform coating with many micro-crevasses. As a result, n-dodecane, water, and CWAs beaded up without wetting the surface, exhibiting large contact angles of 154° for water and 121° for n-dodecane, with a small shedding angle of 5° and contact angle hysteresis of 3.2° for water. The designed coating showed excellent liquid repellence properties against three types of CWAs: 129°, 72°, and 87° for sulfur mustard (HD), soman (GD), and VX nerve agents, respectively. Furthermore, OmniBlock coating shows good mechanical properties under tensile strength and wash tests. This remarkable ability to repel CWAs is likely to have potential military applications in personal protective equipment systems requiring self-cleaning functions.

Zr(OH)4/GO Nanocomposite for the Degradation of Nerve Agent Soman (GD) in High-Humidity Environments.

Zirconium hydroxide, Zr(OH)4 is known to be highly effective for the degradation of chemical nerve agents. Due to the strong interaction force between Zr(OH)4 and the adsorbed water, however, Zr(OH)4 rapidly loses its activity for nerve agents under high-humidity environments, limiting real-world applications. Here, we report a nanocomposite material of Zr(OH)4 and graphene oxide (GO) which showed enhanced stability in humid environments. Zr(OH)4/GO nanocomposite was prepared via a dropwise method, resulting in a well-dispersed and embedded GO in Zr(OH)4 nanocomposite. The nitrogen (N2) isotherm analysis showed that the pore structure of Zr(OH)4/GO nanocomposite is heterogeneous, and its meso-porosity increased from 0.050 to 0.251 cm3/g, compared with pristine Zr(OH)4 prepared. Notably, the composite material showed a better performance for nerve agent soman (GD) degradation hydrolysis under high-humidity air conditions (80% relative humidity) and even in aqueous solution. The soman (GD) degradation by the nanocomposite follows the catalytic reaction with a first-order half-life of 60 min. Water adsorption isotherm analysis and diffuse reflectance infrared Fourier transform (DRIFT) spectra provide direct evidence that the interaction between Zr(OH)4 and the adsorbed water is reduced in Zr(OH)4/GO nanocomposite, indicating that the active sites of Zr(OH)4 for the soman (GD) degradation, such as surface hydroxyl groups are almost available even in high-humidity environments.

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents.

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design-wearable APP (WAPP)-that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents.

Differential Control Efficacies of Vitamin Treatments against Bacterial Wilt and Grey Mould Diseases in Tomato Plants.

Bacterial wilt and grey mould in tomato plants are economically destructive bacterial and fungal diseases caused by Ralstonia solanacearum and Botrytis cinerea, respectively. Various approaches including chemical and biological controls have been attempted to arrest the tomato diseases so far. In this study, in vitro growths of bacterial R. solanacearum and fungal B. cinerea were evaluated using four different vitamins including thiamine (vitamin B1), niacin (vitamin B3), pyridoxine (vitamin B6), and menadione (vitamin K3). In planta efficacies of the four vitamin treatments on tomato protection against both diseases were also demonstrated. All four vitamins showed different in vitro antibacterial activities against R. solanacearum in dose-dependent manners. However, treatment with 2 mM thiamine was only effective in reducing bacterial wilt of detached tomato leaves without phytotoxicity under lower disease pressure (106 colony-forming unit [cfu]/ml). Treatment with the vitamins also differentially reduced in vitro conidial germination and mycelial growth of B. cinerea. The four vitamins slightly reduced the conidial germination, and thiamine, pyridoxine and menadione inhibited the mycelial growth of B. cinerea. Menadione began to drastically suppress the conidial germination and mycelial growth by 5 and 0.5 mM, respectively. Grey mould symptoms on the inoculated tomato leaves were significantly reduced by pyridoxine and menadione pretreatments one day prior to the fungal challenge inoculation. These findings suggest that disease-specific vitamin treatment will be integrated for eco-friendly management of tomato bacterial wilt and grey mould.

Application of Volatile Antifungal Plant Essential Oils for Controlling Pepper Fruit Anthracnose by Colletotrichum gloeosporioides.

Anthracnose caused by Colletotrichum gloeosporioides has been destructive during pepper fruit production in outdoor fields in Korea. In vitro antifungal activities of 15 different plant essential oils or its components were evaluated during conidial germination and mycelial growth of C. gloeosporioides. In vitro conidial germination was most drastically inhibited by vapour treatments with carvacrol, cinnamon oil, trans-cinnamaldehyde, citral, p-cymene and linalool. Inhibition of the mycelial growth by indirect vapour treatment with essential oils was also demonstrated compared with untreated control. Carvacrol, cinnamon oil, trans-cinnamaldehyde, citral and eugenol were among the most inhibitory plant essential oils by the indirect antifungal efficacies. Plant protection efficacies of the plant essential oils were demonstrated by reduced lesion diameter on the C. gloeosporioides-inoculated immature green pepper fruits compared to the inoculated control fruits without any plant essential oil treatment. In planta test showed that all plant essential oils tested in this study demonstrated plant protection efficacies against pepper fruit anthracnose with similar levels. Thus, application of different plant essential oils can be used for eco-friendly disease management of anthracnose during pepper fruit production.

Functionalization of nanomaterials by non-thermal large area atmospheric pressure plasmas: application to flexible dye-sensitized solar cells.

A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film properties can be obtained by the non-thermal APP method when compared with the thermal sintering process operating at 450 °C. The crystallinity of the anatase TiO2 nanoparticles is significantly improved without thermal agglomeration, while the surface defects such as Ti(3+) ions are eliminated, thus providing efficient charge collecting properties for solar cells. Finally, we successfully fabricated a flexible DSSC with an energy conversion efficiency of 4.2% using a transparent plastic substrate. This work demonstrates the potential of non-thermal APP technology in the area of device-level, nano-enabled material manufacturing.

Renal Dysfunction in Liver Transplant Candidates: Evaluation, Classification and Management in Contemporary Practice.

Renal dysfunction is a common comorbidity in patients with liver failure and is a well-established predictor of both morbidity and mortality among patients awaiting liver transplantation. The etiology of renal failure in patients with cirrhosis can be functional, structural, or represent a combination of potentially reversible physiologic changes and permanent histologic damage. Diagnostic criteria for acute and chronic kidney disease have been established, but cirrhosis poses challenges for accurate assessment of renal function with conventional clinical methods such as serum creatinine and creatinine-based estimating equations. Renal biopsies can have an important role for defining permanent structural damage as part of the pre-transplant evaluation of patients with liver disease; however, coagulopathy, portal hypertension and ascites increase the risk of biopsy-associated complications in cirrhotic patients. While renal dysfunction due to hepatorenal physiology is potentially reversible after liver transplantation, simultaneous kidney liver transplantation and kidney after liver transplant can also improve outcomes in a subset of patients with irreversible renal injury.

Inactivation of Listeria monocytogenes on agar and processed meat surfaces by atmospheric pressure plasma jets.

An apparatus for generating atmospheric pressure plasma (APP) jet was used to investigate the inactivation of Listeria monocytogenes on the surface of agar plates and slices of cooked chicken breast and ham. He, N2 (both 7 L/min), and mixtures of each with O2 (0.07 L/min) were used to produce the plasma jets. After treatment for 2 min with APP jets of He, He + O2, N2, or N2 + O2, the numbers of L. monocytogenes on agar plates were reduced by 0.87, 4.19, 4.26, and 7.59 log units, respectively. Similar treatments reduced the L. monocytogenes inoculated onto sliced chicken breast and ham by 1.37 to 4.73 and 1.94 to 6.52 log units, respectively, according to the input gas used with the N2 + O2 mixture being the most effective. Most APP jets reduced the numbers of aerobic bacteria on the meat surfaces to <10² CFU/g, and the numbers remained below that level of detection after storage at 10 °C for 7 days. The results indicate that APP jets are effective for the inactivation of L. monocytogenes on sliced meats and for prolonging the shelf-life of such foods.