Microbial desalination cells (MDCs) are an emerging concept for simultaneous wastewater treatment and water desalination. This work presents a mathematical model to simulate dynamic behavior of MDCs for the first time through evaluating multiple factors such as organic supply, salt loading, and current generation. Ordinary differential equations were applied to describe the substrate as well as bacterial concentrations in the anode compartment. Local sensitivity analysis was employed to select model parameters that needed to be re-estimated from the previous studies. This model was validated by experimental data from both a bench-and a large-scale MDC system. It could fit current generation fairly well and simulate the change of salt concentration. It was able to predict the response of the MDC with time under various conditions, and also provide information for analyzing the effects of different operating conditions. Furthermore, optimal operating conditions for the MDC used in this study were estimated to have an acetate flow rate of 0.8 mL· min −1 , influent salt concentration of 15 g·L −1 and salt solution flow rate of 0.04 mL·min −1 , and to be operated with an external resistor less than 30 Ω. The MDC model will be helpful with determining operational parameters to achieve optimal desalination in MDCs. ■ INTRODUCTIONWater shortage is a global issue that influences a large population, especially in the developing nations. 1 To alleviate this problem, desalinating seawater or brackish water appears to be an effective approach to provide alternative source of fresh water. However, the high energy consumption associated with desalination processes makes desalinated water prohibitively expensive. For example, reverse osmosis (RO), which is the most widely applied desalination technology, requires 3−7 kWh of energy to produce 1 m 3 of freshwater. 2 Recent development of the microbial desalination cell (MDC) provides a potentially energy-efficient desalination method. 3,4 MDCs use electricity generated from low-grade substrates such as wastewater to drive the desalination process, so that it requires little external energy input (e.g., to drive pumping systems). Therefore, it holds great promise to significantly reduce energy consumption in desalination processes. MDC research is still in an early stage, and studies have been carried out to improve the understanding of MDCs by investigating the key factors, such as the anode organic loading rates, 5 salt loading rates, 6,7 external resistance, 8,9 hydraulic retention time, 9 new functions, 10,11 membrane fouling, 12,13 intermembrane distance, 14 and system configuration. 15 Given complex desalination processes and strong interactions between biological, electrochemical, and engineering factors in MDCs, a proper mathematic model will be essential for the optimization and the scaling up of MDCs. MDCs derive from microbial fuel cells (MFCs) by adding a third compartment between the anode and the cathode, separated by anion or cation exchange membranes for ...

Steatosis, i.e., the accumulation of fat in hepatocytes, plays an important role in the progression of non-alcoholic fatty liver disease (NAFLD). It has been shown that STAT3 activation is involved in a decrease of lipid accumulation while C∕EBP is correlated with an increase of fat content and steatosis. It is known that STAT3 and C∕EBP are activated by IL-6 and that IL-6 signalling is also affected by IL-10, even though the exact mechanism is unclear. This paper develops a model for IL-6 and IL-10 signal transduction and then investigates the effect that stimulation with these cytokines has on the transcription factor dynamics. In an initial step, some parameters of a previously developed IL-6 signalling model are re-estimated based upon newly developed experimental data for the Jak-STAT pathway. Furthermore, the Erk-C∕EBP pathway model is extended to also include the activated transcription factor C∕EBP in the nucleus. Since IL-10 signals through the Jak-STAT but not the Erk-C∕EBP pathway, a model was developed which includes interaction between IL-6 and IL-10 signalling as both mechanisms share signal transduction through the Jak-STAT pathway. Based upon the model, the activity ratio of Jak-STAT and Erk-C∕EBP was investigated for different stimulation levels of IL-6 and IL-10.

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Background: The development of quantitative models of signal transduction, as well as parameter estimation to improve existing models, depends on the ability to obtain quantitative information about various proteins that are part of the signaling pathway. However, commonly-used measurement techniques such as Western blots and mobility shift assays provide only qualitative or semi-quantitative data which cannot be used for estimating parameters. Thus there is a clear need for techniques that enable quantitative determination of signal transduction intermediates.

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