Bacillus cereus is a spore-forming foodborne pathogen known for its high resistance to conventional sterilization methods, posing a persistent threat to food safety. In this study, a novel inactivation system was developed by combining superheated steam (SHS) with cold plasma, aiming to achieve enhanced inactivation of B. cereus spores on stainless steel surfaces. The system was designed to inject cold plasma gas directly into the SHS flow, ensuring simultaneous exposure to thermal and oxidative stress. Combined SHS-plasma (SHS-P) treatment at 150°C for 18.88 min achieved an experimental reduction of 4.88 log CFU/cm2, that is sufficient to satisfy microbiological control requirements for spore-forming pathogens such as B. cereus and Clostridium perfringens in food processing applications. To clarify the inactivation mechanism, dipicolinic acid release, lipid peroxidation, intracellular reactive oxygen species generation, and DNA integrity were assessed. SHS-P induced early iROS accumulation and DNA damage, followed by increased DPA release and membrane lipid peroxidation over time. Transmission electron microscopy further confirmed structural disruption in endospores following SHS-P treatment. Notably, the synergistic effects of SHS-P were more pronounced at 150°C than at 200°C, possibly due to differences in relative humidity and reactive species stability. These findings suggest that SHS-P is a promising, efficient strategy for inactivating B. cereus spores under milder conditions, with potential application in improving the microbiological safety of food contact surfaces without excessive thermal or chemical inputs.
Deep eutectic solvent (DES) pretreatment followed by mechanical fibrillation is a promising approach for producing lignocellulosic nanofibrils (LCNFs) with enhanced properties. Despite considerable efforts to optimize DES pretreatment conditions, the effect of the washing solvent, specifically its water content, on lignin content and LCNF properties has been largely overlooked. This study investigates the impact of water content in a dioxane/water washing solvent following DES pretreatment on red pine wood powder using a choline chloride/lactic acid DES. The variation in pretreatment yield and lignin content were first analyzed. Subsequent mechanical fibrillation produced LCNFs with differing lignin contents. Increase in the water content from 20
Surface modification techniques, such as shot peening and ultrasonic nanocrystal surface modification, are widely used to improve wear, corrosion, and fatigue resistance, as well as strength by tailoring the near-surface microstructure. However, the severe plastic deformation accompanying these processes often results in high dislocation densities and limited strain accommodation capability, leading to a deterioration of ductility. In this study, argon plasma bombardment introduces a graded compressive residual stress field at the surface while reducing dislocation density in a CoCrFeMnNi high-entropy alloy. This surface modification simultaneously increases yield strength, tensile strength, uniform elongation, and total elongation, demonstrating a simple route to enhance strength-ductility synergy without severe surface deformation.
Estimating subsurface properties like hydraulic conductivity using hydrogeological data alone is challenging in field sites with sparse wells. Geophysical data, including Self-potential (SP) and Magnetotelluric (MT), can improve understanding of hydrogeological structures and interpolate data between wells. However, determining hydraulic conductivity requires a proper petrophysical relationship between hydraulic conductivity and inferred geophysical properties, which may not exist or be unique. In this work, we propose a joint-inversion approach without assuming petrophysical relationships, using self-potential data to connect groundwater flow velocity to electrical potential differences, and MT data to estimate hydraulic conductivity and electrical conductivity. A spectral method is employed for the self-potential forward problem. To accelerate joint data inversion, a dimension reduction technique through the Principal Component Geostatistical Approach is used. The applicability and robustness of the joint-inversion method are demonstrated through inversion tests using hydrogeophysical data sets generated from subsurface models with and without petrophysical relationships. The joint hydraulic head-SP-MT data inversion can reasonably estimate hydraulic conductivity and electrical resistivity, even without knowledge of a one-to-one petrophysical relationship. On average, joint inversion yields a 25 improvement in hydraulic conductivity estimates compared to single data-type inversion. Our proposed joint inversion approach, with SP-data compensating for the absence of a known petrophysical relationship, provided close agreement with joint inversion of head and MT data using a known petrophysical relationship. Successful inversion tests demonstrate the usefulness of SP data in connecting hydrogeological properties and geophysical data without requiring a petrophysical relationship.
