Dynamic modeling of syngas fermentation in a continuous stirred-tank reactor: Multi-response parameter estimation and process optimization

Syngas fermentation is one of the bets for the future sustainable biobased economies due to its potential as an intermediate step in the conversion of waste carbon to ethanol fuel and other chemicals. Integrated with gasification and suitable downstream processing, it may constitute an efficient and competitive route for the valorization of various waste materials, especially if systems engineering principles are employed targeting process optimization. In this study, a dynamic multi-response model is presented for syngas fermentation with acetogenic bacteria in a continuous stirred-tank reactor, accounting for gas–liquid mass transfer, substrate (CO, H₂) uptake, biomass growth and death, acetic acid reassimilation, and product selectivity. The unknown parameters were estimated from literature data using the maximum likelihood principle with a multi-response nonlinear modeling framework and metaheuristic optimization, and model adequacy was verified with statistical analysis via generation of confidence intervals as well as parameter significance tests. The model was then used to study the effects of process conditions (gas composition, dilution rate, gas flow rates, and cell recycle) as well as the sensitivity of kinetic parameters, and multiobjective genetic algorithm was used to maximize ethanol productivity and CO conversion. It was observed that these two objectives were clearly conflicting when CO-rich gas was used, but increasing the content of H₂ favored higher productivities while maintaining 100% CO conversion. The maximum productivity predicted with full conversion was 2 g·L⁻¹·hr⁻¹ with a feed gas composition of 54% CO and 46% H₂ and a dilution rate of 0.06 hr⁻¹ with roughly 90% of cell recycle.     

Effects of anti-inflammatory drugs upon nitrate and myeloperoxidase levels in the mouse pleurisy induced by carrageenan.

The effects of several drugs (terfenadine, bradykinin B2 receptor antagonists: HOE 140, NPC 17731, diacerein, indomethacin, meloxicam, nabumetone, and dexamethasone) upon myeloperoxidase and nitrate levels were analyzed in an inflammation model characterized by biphasic peaks (4 and 48 h) of cell migration and of fluid leakage. Myeloperoxidase levels were significantly higher only in the first phase (4 h; median and range; 537.5; 323.6-683.7 mU/ml; P < 0.01), whereas increased mean nitrate levels were detected in both phases (4 h: 19.0; 6.2-32 microM and 48 h: 13.7; 8.9-17.8 microM; P < 0.01). Enhancement of both cell migration and myeloperoxidase levels, 4 h after pleurisy induction, was effectively inhibited by all studied drugs. All of them, except diacerein also inhibited exudation. At this time, nabumetone and diacerein also significantly reduced nitrate levels (P < 0.01). Regarding the second phase (48 h), although dexamethasone, diacerein, and terfenadine decreased either cell migration or exudation, no drugs caused any change in the levels of nitrate. These results indicate that the degree of inhibition of the tested drugs upon the parameters studied do not match, suggesting that differences in these effects may certainly interfere with their efficacy.     

Magnetic material in the ocellar spot and lateral line of tomtates Haemulon aurolineatum

The presence of magnetic material in tissues of lateral line and ocellar spot of tomtates Haemulon aurolineatum is shown using the ferromagnetic resonance technique. For the first time magnetic material is reported in the ocellar spot. The magnetic material detected in these structures of H. aurolineatum suggests that this species could use magnetic orientation during its nocturnal foraging, and the relevance and role of this material with respect to schooling movements is discussed.     

Familial Clustering of Abdominal Visceral Fat and Total Fat Mass: The Québec Family Study

The evidence for common familial factors underlying total fat mass (estimated from underwater weighing) and abdominal visceral fat (assessed from CT scan) was examined in families participating in phase 2 of the Québec Family Study (QFS) using a bivariate familial correlation model. Previous QFS investigations suggest that both genetic (major and polygenic) and familial environmental factors influence each phenotype, accounting for between 55% to 71% of the phenotypic variance in fat mass, and between 55% to 72% for abdominal visceral fat The current study suggests that the bivariate familial effect ranges from 29% to 50%. This pattern suggests that there may be common familial determinants for abdominal visceral fat and total fat mass, as well as additional familial factors which are specific to each. The relatively high spouse cross-trait correlations usually suggest that a large percent of the bivariate familial effect may be environmental in origin. However, if mating is not random, then the spouse resemblance may reflect either genetic or environmental causes, depending on the source [i.e., through similar genes or cohabitation (environmental) effects]. Finally, there are significant sex differences in the magnitude of the familial cross-trait correlations involving parents, but not offspring, suggesting complex generation (i.e., age) and sex effects. For example, genes may turn on or off as a function of age and sex, and/or there may be an accumulation over time of effects due to the environment which may vary by sex. Whether the common familial factors are genetic (major and/or polygenic), environmental, or some combination of both, and whether the familial expression depends on sex and/or age warrants further investigation using more complex models.