Formation of Salmonella Typhimurium Biofilm Under Various Growth Conditions and its Sensitivity to Industrial Sanitizers

Master'sMASTER OF SCIENC

Immunotoxicity of Zinc Oxide (ZnO) Nanoparticles (NPs) in vitro and in vivo

Dept. of Medicine/석사While Zinc Oxide (ZnO) nanoparticle (NP) has been recognized to have promising applications in biomedicine, its immunotoxicity has been inconsistent and even contradictory. To address this issue, we investigated whether ZnO NPs with different sizes (20 nm or 100 nm) and electrostatic charges (negative or positive) would cause immunotoxicity in vitro and in vivo, and explored their underlying molecular mechanism. Using Raw 264.7 cell line, we examined cell viability, reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), and antioxidant enzyme activity to explore the immunotoxicity mechanism of ZnO NPs in vitro. We found that in cell viability assay (CCK-8, real-time xCelligence) ZnO NPs with different size and charge could induce differential cytotoxicity to Raw 264.7 cells. Specifically, the positively charged ZnO NPs exerted higher cytotoxicity than the negatively charged one. Molecular study to unravel the mechanism of immune cell toxicity showed that overall, treatment of ZnO NPs decreased MMP, generated intracellular ROS, and reduced antioxidant enzyme activity such as glutathione peroxidase (GPx). Next, to gauge systemic immunotoxicity, we assessed immune responses of C57BL/6 mice after orally administration of sub-lethal dose of ZnO NPs for two weeks. Oral intake of ZnO NPs significantly decreased body weight gain. In parallel, ZnO NPs did not alter the cell-mediated immune response in mice but suppressed innate immunity such as NK cell activity. The CD4+/CD8+ ratio was slightly reduced which implies the alteration of immune status induced by ZnO NPs. Accordingly, nitric oxide (NO) production from splenocyte culture supernatant in ZnO NP-fed mice was lower than control. Consistently, serum levels of pro/anti-inflammatory (IL-1, TNF-α, and IL-10) and Th1 cytokines (IFN-γ, IL-12) in ZnO NP-fed mice were significantly suppressed. Collectively, our results indicate that different sized- and charged-ZnO NPs would cause in vitro and in vivo immunotoxicity, of which nature is a minor immunosuppression. This has important implications for individuals who may be chronically exposed to ZnO NPs.ope

A DPLL(T) Framework for Verifying Deep Neural Networks

Deep Neural Networks (DNNs) have emerged as an effective approach to tackling real-world problems. However, like human-written software, automatically-generated DNNs can have bugs and be attacked. This thus attracts many recent interests in developing effective and scalable DNN verification techniques and tools. In this work, we introduce a NeuralSAT, a new constraint solving approach to DNN verification. The design of NeuralSAT follows the DPLL(T) algorithm used modern SMT solving, which includes (conflict) clause learning, abstraction, and theory solving, and thus NeuralSAT can be considered as an SMT framework for DNNs. Preliminary results show that the NeuralSAT prototype is competitive to the state-of-the-art. We hope, with proper optimization and engineering, NeuralSAT will carry the power and success of modern SAT/SMT solvers to DNN verification. NeuralSAT is avaliable from: https://github.com/dynaroars/neuralsat-solverComment: 27 pages, 8 figures. NeuralSAT is avaliable from: https://github.com/dynaroars/neuralsat-solve

Nitrification of Groundwater Contaminated with NH₄⁺ Using a Novel Acryl-Resin Fiber for Biomass Attachment

Joint Research on Environmental Science and Technology for the Eart

The Visible Light Activity of the TiO2 and TiO2:V4+ Photocatalyst

TiO2 and vanadium‐doped TiO2 nanoparticles were synthesized by using the hydrothermal method. The V doping contents are 0.0; 0.1; 0.3; 0.5; 0.7 and 0.9% molar. The vanadium‐doped TiO2 nanoparticles have identical anatase phase with an average crystal size of 10‐20nm. The oleic acid and ethanol solvents with different molar concentrations can make spherical nanograins, or stick form grains, which influence the photo activity of the materials. The absorption spectra of doped samples exhibited long-tailed absorption in the visible light region above 380nm. The visible light photocatalytic activity was evaluated by the degradation of phenol aqueous solutions; after 360 min. under the visible irradiation, the normalized concentration of phenol decreased to 9%

Characteristics of shear strength at the interface between two soil layers in ring shear apparatus

The slopes containing discontinuous planes such as bedding planes, rupture, or boundary between two soil layers are often prone to sliding. Thus, the characteristics of shear strength mobilized along the discontinuous planes should be examined. In this study, the shear strength at the interface between two different soil layers will be investigated based on ring shear test. The combined sample comprising of one kaolin layer and one kaolin + bentonite mixture layer was used to simulate the discontinuous planes between two soil layers. A number of ring shear tests were conducted on these samples at a normal stress of 98 kPa and shear rates from 0.02 to 20 mm/min using a multi-stage of shearing rates procedure. The research results indicate that the shear strength at the interface sharply increases to reach the peak value after a small shear displacement, then drops to the residual value. The residual interface strength tends to increase with increasing shear rates above 2 mm/min and the level of increase in residual interface strength depends on the contact surface. Furthermore, the effect of the order sample layer in combined samples can be ignored when determining the peak, the residual interface strengths as well as the rate effect on residual interface strength in the laboratory