Ethylene Process Optimization. Constraint Relaxation And Bounds Adjustment

Heavily constrained, mixed integer optimization problems present a difficult test for optimization algorithms. This paper examines optimization of the ethylene process (from ethane) using a flowsheet simulation model and the adaptive random search. Optimization resulted in an improvement in annual earnings of $1.15 MM over the usual ethylene process design. This process has both continuous and discrete variables and has sensitive implicit constraints in the pyrolysis furnace. The search efficiency was found to be improved by relaxing these constraints early in the search and then restoring the constraints as the optimum is approached. The search efficiency was also improved by testing each independent variable for its optimal explicit bound and using these bounds as the starting point for the optimization. Significant improvements in the economics ($0.7 MM per year) were found by examining and slightly adjusting the variable boundaries at the optimum. These results suggest that variable bounds should be established in conjunction with the optimization study. © 1979, American Chemical Society. All rights reserved

Clostridiumm ljungdahlii, an anaerobic ethanol and acetate producing microorganism

A newly discovered microorganism was isolated in a biologically pure culture and designated Clostridium ljungdahlii, having the identifying characteristics of ATCC No. 49587. Cultured in an aqueous nutrient medium under anaerobic conditions, this microorganism is capable of producing ethanol and acetate from CO and H2O and/or CO2 and H2 in synthesis gas. Under optimal growth conditions, the microorganism produces acetate in preference to ethanol. Conversely, under non-growth conditions, ethanol production is favored over acetate

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Final Report - "CO2 Sequestration in Cell Biomass of Chlorobium Thiosulfatophilum"

World carbon dioxide emissions from the combustion of fossil fuels have increased at a rate of about 3 percent per year during the last 40 years to over 24 billion tons today. While a number of methods have been proposed and are under study for dealing with the carbon dioxide problem, all have advantages as well as disadvantages which limit their application. The anaerobic bacterium Chlorobium thiosulfatophilum uses hydrogen sulfide and carbon dioxide to produce elemental sulfur and cell biomass. The overall objective of this project is to develop a commercial process for the biological sequestration of carbon dioxide and simultaneous conversion of hydrogen sulfide to elemental sulfur. The Phase I study successfully demonstrated the technical feasibility of utilizing this bacterium for carbon dioxide sequestration and hydrogen sulfide conversion to elemental sulfur by utilizing the bacterium in continuous reactor studies. Phase II studies involved an advanced research and development to develop the engineering and scale-up parameters for commercialization of the technology. Tasks include culture isolation and optimization studies, further continuous reactor studies, light delivery systems, high pressure studies, process scale-up, a market analysis and economic projections. A number of anaerobic and aerobic microorgansims, both non-photosynthetic and photosynthetic, were examined to find those with the fastest rates for detailed study to continuous culture experiments. C. thiosulfatophilum was selected for study to anaerobically produce sulfur and Thiomicrospira crunogena waws selected for study to produce sulfate non-photosynthetically. Optimal conditions for growth, H2S and CO2 comparison, supplying light and separating sulfur were defined. The design and economic projections show that light supply for photosynthetic reactions is far too expensive, even when solar systems are considered. However, the aerobic non-photosynthetic reaction to produce sulfate with T. crunogena produces a reasonable return when treating a sour gas stream of 120 million SCFD containing 2.5 percent H2S. In this case, the primary source of revenue is from desulfurization of the gas stream. While the technology has significant application in sequestering carbon dioxide in cell biomass or single cell proten (SCP), perhaps the most immediate application is in desulfurizing LGNG or other gas streams. This biological approach is a viable economical alternative to existing hydrogen sulfide removal technology, and is not sensitive to the presence of hydrocarbons which act as catalyst poisons

Peptidomimetic Small Molecules Disrupt Type IV Secretion System Activity in Diverse Bacterial Pathogens

Bacteria utilize complex type IV secretion systems (T4SSs) to translocate diverse effector proteins or DNA into target cells. Despite the importance of T4SSs in bacterial pathogenesis, the mechanism by which these translocation machineries deliver cargo across the bacterial envelope remains poorly understood, and very few studies have investigated the use of synthetic molecules to disrupt T4SS-mediated transport. Here, we describe two synthetic small molecules (C10 and KSK85) that disrupt T4SS-dependent processes in multiple bacterial pathogens. Helicobacter pylori exploits a pilus appendage associated with the cag T4SS to inject an oncogenic effector protein (CagA) and peptidoglycan into gastric epithelial cells. In H. pylori, KSK85 impedes biogenesis of the pilus appendage associated with the cag T4SS, while C10 disrupts cag T4SS activity without perturbing pilus assembly. In addition to the effects in H. pylori, we demonstrate that these compounds disrupt interbacterial DNA transfer by conjugative T4SSs in Escherichia coli and impede vir T4SS-mediated DNA delivery by Agrobacterium tumefaciens in a plant model of infection. Of note, C10 effectively disarmed dissemination of a derepressed IncF plasmid into a recipient bacterial population, thus demonstrating the potential of these compounds in mitigating the spread of antibiotic resistance determinants driven by conjugation. To our knowledge, this study is the first report of synthetic small molecules that impair delivery of both effector protein and DNA cargos by diverse T4SSs. IMPORTANCE Many human and plant pathogens utilize complex nanomachines called type IV secretion systems (T4SSs) to transport proteins and DNA to target cells. In addition to delivery of harmful effector proteins into target cells, T4SSs can disseminate genetic determinants that confer antibiotic resistance among bacterial populations. In this study, we sought to identify compounds that disrupt T4SS-mediated processes. Using the human gastric pathogen H. pylori as a model system, we identified and characterized two small molecules that prevent transfer of an oncogenic effector protein to host cells. We discovered that these small molecules also prevented the spread of antibiotic resistance plasmids in E. coli populations and diminished the transfer of tumor-inducing DNA from the plant pathogen A. tumefaciens to target cells. Thus, these compounds are versatile molecular tools that can be used to study and disarm these important bacterial machines