Pathogenic mechanisms of Photobacterium damselae subspecies piscicida in hybrid striped bass

Photobacterium damselae subspecies piscicida, previously known as Pasteurella piscicida, is an important pathogen of hybrid striped bass and many fish species cultured in brackish water in the United States, Japan, Europe, and the Mediterranean. The purpose of this study is to investigate virulence mechanisms that contribute to the pathogenesis of this organism. The ability of P. damselae to survive/replicate within hybrid striped bass macrophages was evaluated with an in vitro killing assay. Results indicated that the numbers of bacteria recovered from macrophages at 3, 6, 12, and 18 hours of incubation increased significantly over time. In contrast, the numbers of Escherichia coli control strain recovered from macrophages declined at the same designated incubation times. Light and electron microscopy confirmed internalization, uptake, and multiplication of bacteria within spacious, clear vacuoles in the macrophages. Using acid phosphatase as a lysosomal marker, it was shown that P. damselae inhibits phagolysosomal fusion. Invasion and replication of P. damselae within epithelioma papillosum carpio (EPC), channel catfish ovary (CCO), and fathead minnow (FHM) cells lines was also evaluated using an in vitro invasion assay. All three cell lines were susceptible to invasion and supported replication of P. damselae. Fathead minnow cells were more susceptible to invasion than the other two cell lines as indicated by greater numbers of infected cells and recovered bacteria at time 0. Using light and electron microscopy, invasion of cells by bacteria was observed as early as 30 minutes after infection, and intracellular bacteria were observed in large, clear, membrane-bound vacuoles. The intracellular location of P. damselae was confirmed using ruthenium red staining to discriminate between the extra- and intra-cellular spaces. Using flow cytometry, results indicated that P. damselae induces apoptosis in phagocytes obtained from hybrid striped bass head kidney and after 12, 18, and 24 hours of incubation, the relative numbers of cells infected with P. damselae showing signs of apoptosis increased over time and were significantly greater than the controls. The relative numbers of apoptotic cells that were infected with the formalin-killed strain increased, but not significantly, above the control after the same designated times of incubation

Optimization of supercritical extraction of nimbin from neem seeds in presence of methanol as co-solvent

Mathematical modeling and optimization of the extraction of nimbin from neemseeds using supercritical carbon dioxide with methanol as co-solvent is the subject of this study. At first a correlation for Sherwood number (Sh) as a function of Reynolds number (Re) and Schmidt number (Sc) was proposed using a Genetic Algorithm (GA) technique. This correlation was compared to previous correlations and was found to give the most accurate results. Moreover, optimum conditions (temperature, pressure, solvent flow rate and particle diameter) which maximizes the extraction yield have been determined using GA. At the next step, methanol was used as a co-solvent and the dynamic equilibrium constant of solute between the solid phase and the solvent was estimated. By applying the new determined equilibrium constant, good agreement between the model and experimental data was observed

Simulation-optimization framework for synthesis and design of natural gas downstream utilization networks

Many potential diversification and conversion options are available for utilization of natural gas resources, and several design configurations and technology choices exist for conversion of natural gas to value-added products. Therefore, a detailed mathematical model is desirable for selection of optimal configuration and operating mode among the various options available. In this study, we present a simulation-optimization framework for the optimal selection of economic and environmentally sustainable pathways for natural gas downstream utilization networks by optimizing process design and operational decisions. The main processes (e.g., LNG, GTL, and methanol production), along with different design alternatives in terms of flow-sheeting for each main processing unit (namely syngas preparation, liquefaction, N2 rejection, hydrogen, FT synthesis, methanol synthesis, FT upgrade, and methanol upgrade units), are used for superstructure development. These processes are simulated using ASPEN Plus V7.3 to determine the yields of different processing units under various operating modes. The model has been applied to maximize total profit of the natural gas utilization system with penalties for environmental impact, represented by CO2eq emission obtained using ASPEN Plus for each flowsheet configuration and operating mode options. The performance of the proposed modeling framework is demonstrated using a case study. 2018 by the authors.The authors would like to acknowledge the financial support from NSERC and from Qatar University to conduct this research. A.E. and M.A.S. would also like to acknowledge the Gas Research Center (GRC) at the Petroleum Institute during the later stages of this research.Scopu

Modeling the Interaction between β

The effect of β-amyloid aggregates on activity of choline acetyltransferase (ChAT) which is responsible for synthesizing acetylcholine (ACh) in human brain is investigated through the two-enzyme/two-compartment (2E2C) model where the presynaptic neuron is considered as compartment 1 while both the synaptic cleft and the postsynaptic neuron are considered as compartment 2 through suggesting three different kinetic mechanisms for the inhibition effect. It is found that the incorporation of ChAT inhibition by β-amyloid aggregates into the 2E2C model is able to yield dynamic solutions for concentrations of generated β-amyloid, ACh, choline, acetate, and pH in addition to the rates of ACh synthesis and ACh hydrolysis in compartments 1 and 2. It is observed that ChAT activity needs a high concentration of β-amyloid aggregates production rate. It is found that ChAT activity is reduced significantly when neurons are exposed to high levels of β-amyloid aggregates leading to reduction in levels of ACh which is one of the most significant physiological symptoms of AD. Furthermore, the system of ACh neurocycle is dominated by the oscillatory behavior when ChAT enzyme is completely inhibited by β-amyloid. It is observed that the direct inactivation of ChAT by β-amyloid aggregates may be a probable mechanism contributing to the development of AD

Membrane Separation for Gases: Materials, Preparation Methods and Transport Mechanism

Gas adsorption and permeation of CO2 gas weremeasured on two carbon molecular sieve membranes over awide pressure range. The two membrane samples werefabricated under similar conditions but with different degreesof carbonization. The pressure dependence of the permeationtime lag was investigated and it is found that the diffusioncoefficient takes a stronger functional dependence on loadingthan the Darken relation and this dependence increases withthe degree of carbonization

Probing the Structure-Performance Relationship of Lithium-Ion Battery Cathodes Using Pore-Networks Extracted from Three-Phase Tomograms

Pore-scale simulations of Li-ion battery electrodes were conducted using both pore-network modeling and direct numerical simulation. Ternary tomographic images of NMC811 cathodes were obtained and used to create the pore-scale computational domains. A novel network extraction method was developed to manage the extraction of N-phase networks which was used to extract all three phases of NMC-811 electrode along with their interconnections Pore network results compared favorably with direct numerical simulations (DNS) in terms of effective transport properties of each phase but were obtained in significantly less time. Simulations were then conducted with combined diffusion-reaction to simulate the limiting current behavior. It was found that when considering only ion and electron transport, the electrode structure could support current densities about 300 times higher than experimentally observed values. Additional case studies were conducted to illustrate the necessity of ternary images which allow separate consideration of carbon binder domain and active material. The results showed a 24.4% decrease in current density when the carbon binder was treated as a separate phase compared to lumping the CBD and active material into a single phase. The impact of nanoporosity in the carbon binder phase was also explored and found to enhance the reaction rate by 16.8% compared to solid binder. In addition, the developed technique used 58 times larger domain volume than DNS which opens up the possibility of modelling much larger tomographic data sets, enabling representative areas of typically inhomogeneous battery electrodes to be modelled accurately, and proposes a solution to the conflicting needs of high-resolution imaging and large volumes for image-based modelling. For the first time, three-phase pore network modelling of battery electrodes has been demonstrated and evaluated, opening the path towards a new modelling framework for lithium ion batteries

Comparing Non-Steady State Emissions under Start-Up and Shut-Down Operating Conditions with Steady State Emissions for Several Industrial Sectors: A Literature Review

This study investigates the emissions of various industrial facilities under start-up, shut-down, and normal operations. The industries that have been investigated include power and/or heat generation, energy-from-waste generation, nuclear power generation, sulphuric acid production, ethylene production, petrochemical production, and waste incineration. The study investigated multiple facilities worldwide for each of these industrial categories. The different potential contaminants characteristic of each industry type have been investigated and the emissions of these contaminants under non-steady state have been compared to the steady state emissions. Where available, trends have been developed to identify the circumstances, i.e., the industrial sector and contaminant, under which the assessment and consideration of emissions from start-up and shut-down events is necessary for each industry. These trends differ by industrial sector and contaminant. For example, the study shows that sulphur dioxide (SO2) emissions should be assessed for the start-up operations of sulphuric acid production plants, but may not need to be assessed for the start-up operations of a conventional power generation facility. The trends developed as part of this research paper will help air permit applicants to effectively allocate their resources when assessing emissions related to non-steady state operations. Additionally, it will ensure that emissions are assessed for the worst-case scenario. This is especially important when emissions under start-up and shut-down operations have the potential to exceed enforceable emission limits. Thus, assessing emissions for the worst-case scenario can help in preventing the emissions from adversely impacting public health and the environment

Simulation-Optimization Framework for Synthesis and Design of Natural Gas Downstream Utilization Networks

Many potential diversification and conversion options are available for utilization of natural gas resources, and several design configurations and technology choices exist for conversion of natural gas to value-added products. Therefore, a detailed mathematical model is desirable for selection of optimal configuration and operating mode among the various options available. In this study, we present a simulation-optimization framework for the optimal selection of economic and environmentally sustainable pathways for natural gas downstream utilization networks by optimizing process design and operational decisions. The main processes (e.g., LNG, GTL, and methanol production), along with different design alternatives in terms of flow-sheeting for each main processing unit (namely syngas preparation, liquefaction, N-2 rejection, hydrogen, FT synthesis, methanol synthesis, FT upgrade, and methanol upgrade units), are used for superstructure development. These processes are simulated using ASPEN Plus V7.3 to determine the yields of different processing units under various operating modes. The model has been applied to maximize total profit of the natural gas utilization system with penalties for environmental impact, represented by CO2eq emission obtained using ASPEN Plus for each flowsheet configuration and operating mode options. The performance of the proposed modeling framework is demonstrated using a case study.NSERCQatar Universit

Probing the Structure-Performance Relationship of Lithium-Ion Battery Cathodes Using Pore-Networks Extracted from Three-Phase Tomograms

Pore-scale simulations of Li-ion battery electrodes were conducted using both pore-network modeling and direct numerical simulation. Ternary tomographic images of NMC811 cathodes were obtained and used to create the pore-scale computational domains. A novel network extraction method was developed to manage the extraction of N-phase networks which was used to extract all three phases of NMC-811 electrode along with their interconnections Pore network results compared favorably with direct numerical simulations (DNS) in terms of effective transport properties of each phase but were obtained in significantly less time. Simulations were then conducted with combined diffusion-reaction to simulate the limiting current behavior. It was found that when considering only ion and electron transport, the electrode structure could support current densities about 300 times higher than experimentally observed values. Additional case studies were conducted to illustrate the necessity of ternary images which allow separate consideration of carbon binder domain and active material. The results showed a 24.4% decrease in current density when the carbon binder was treated as a separate phase compared to lumping the CBD and active material into a single phase. The impact of nanoporosity in the carbon binder phase was also explored and found to enhance the reaction rate by 16.8% compared to solid binder. In addition, the developed technique used 58 times larger domain volume than DNS which opens up the possibility of modelling much larger tomographic data sets, enabling representative areas of typically inhomogeneous battery electrodes to be modelled accurately, and proposes a solution to the conflicting needs of high-resolution imaging and large volumes for image-based modelling. For the first time, three-phase pore network modelling of battery electrodes has been demonstrated and evaluated, opening the path towards a new modelling framework for lithium ion batteries.The described here was financially supported by the University of Engineering and Technology Lahore, Pakistan as well as the Natural Science and Engineering Research Council (NSERC) of Canada and in the UK by the Faraday Institution (EP/R042012/1 and EP/R042063/1). Pablo A. García-Salaberri thanks the support from the STFC Early Career Award (ST/R006873/1) during his stay at the Electrochemical Innovation La