Chemical and Biomolecular Engineering Research Works
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- ItemHigh-energy and low-cost membrane-free chlorine flow battery(Springer Nature, 2022-03-11) Hou, Singyuk; Chen, Long; Fan, Xiulin; Fan, Xiaotong; Ji, Xiao; Wang, Boyu; Cui, Chunyu; Chen, Ji; Yang, Chongyin; Wang, Wei; Li, Chunzhong; Wang, ChunshengGrid-scale energy storage is essential for reliable electricity transmission and renewable energy integration. Redox flow batteries (RFB) provide affordable and scalable solutions for stationary energy storage. However, most of the current RFB chemistries are based on expensive transition metal ions or synthetic organics. Here, we report a reversible chlorine redox flow battery starting from the electrolysis of aqueous NaCl electrolyte and the as-produced Cl2 is extracted and stored in the carbon tetrachloride (CCl4) or mineral spirit flow. The immiscibility between the CCl4 or mineral spirit and NaCl electrolyte enables a membrane-free design with an energy efficiency of >91% at 10 mA/cm2 and an energy density of 125.7 Wh/L. The chlorine flow battery can meet the stringent price and reliability target for stationary energy storage with the inherently low-cost active materials (~$5/kWh) and the highly reversible Cl2/Cl− redox reaction.
- ItemUnderstanding the Impact of Hydrogen Activation by SrCe 0.8Zr0.2O 3−δ Perovskite Membrane Material on Direct Non-Oxidative Methane Conversion(Frontiers, 2022-01-10) Cheng, Sichao; Oh, Su Cheun; Sakbodin, Mann; Qiu, Limei; Diao, Yuxia; Liu, DongxiaUnderstanding the Impact of Hydrogen Activation by SrCe 0.8Zr0.2O 3−δ Perovskite Membrane Material on Direct Non-Oxidative Methane Conversion Sichao Cheng 1†, Su Cheun Oh 1†, Mann Sakbodin 1 , Limei Qiu 2 , Yuxia Diao 2 and Dongxia Liu 1 * 1 Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, United States, 2 Research Institute of Petroleum Processing, SINOPEC, Beijing, China Direct non-oxidative methane conversion (DNMC) converts methane (CH 4 ) in one step to olefin and aromatic hydrocarbons and hydrogen (H 2) co-product. Membrane reactors comprising methane activation catalysts and H 2 -permeable membranes can enhance methane conversion by in situ H 2 removal via Le Chatelier’s principle. Rigorous description of H 2 kinetic effects on both membrane and catalyst materials in the membrane reactor, however, has been rarely studied. In this work, we report the impact of hydrogen activation by hydrogen-permeable SrCe 0.8Zr 0.2O 3−δ (SCZO) perovskite oxide material on DNMC over an iron/silica catalyst. The SCZO oxide has mixed ionic and electronic conductivity and is capable of H2 activation into protons and electrons for H 2 permeation. In the fixed- bed reactor packed with a mixture of SCZO oxide and iron/silica catalyst, stable and high methane conversion and low coke selectivity in DNMC was achieved by co-feeding of H 2 in methane stream. The characterizations show that SCZO activates H 2 to favor “soft coke” formation on the catalyst. The SCZO could absorb H 2 in situ to lower its local concentration to mitigate the reverse reaction of DNMC in the tested conditions. The co-existence of H 2 co-feed, SCZO oxide, and DNMC catalyst in the present study mimics the conditions of DNMC in the H2 -permeable SCZO membrane reactor. The findings in this work offer the mechanistic understanding of and guidance for the design of H2 -permeable membrane reactors for DNMC and other alkane dehydrogenation reactions.
- ItemRNA Interference mediated knockdown of genes in order to increase protein production using the baculovirus expression system(Springer Nature, 2006-10-10) Hebert, Colin; Kim, Eun Jeong; Kramer, Shannon F; Valdes, James J; Bentley, William E
- ItemMicrobial nar-GFP cell sensors reveal oxygen limitations in highly agitated and aerated laboratory-scale fermentors(Springer Nature, 2009-01-15) Garcia, Jose R; Cha, Hyung J; Rao, Govind; Marten, Mark R; Bentley, William ESmall-scale microbial fermentations are often assumed to be homogeneous, and oxygen limitation due to inadequate micromixing is often overlooked as a potential problem. To assess the relative degree of micromixing, and hence propensity for oxygen limitation, a new cellular oxygen sensor has been developed. The oxygen responsive E. coli nitrate reductase (nar) promoter was used to construct an oxygen reporter plasmid (pNar-GFPuv) which allows cell-based reporting of oxygen limitation. Because there are greater than 109 cells in a fermentor, one can outfit a vessel with more than 109 sensors. Our concept was tested in high density, lab-scale (5 L), fed-batch, E. coli fermentations operated with varied mixing efficiency – one verses four impellers. In both cases, bioreactors were maintained identically at greater than 80% dissolved oxygen (DO) during batch phase and at approximately 20% DO during fed-batch phase. Trends for glucose consumption, biomass and DO showed nearly identical behavior. However, fermentations with only one impeller showed significantly higher GFPuv expression than those with four, indicating a higher degree of fluid segregation sufficient for cellular oxygen deprivation. As the characteristic time for GFPuv expression (approx 90 min.) is much larger than that for mixing (approx 10 s), increased specific fluorescence represents an averaged effect of oxygen limitation over time and by natural extension, over space. Thus, the pNar-GFPuv plasmid enabled bioreactor-wide oxygen sensing in that bacterial cells served as individual recirculating sensors integrating their responses over space and time. We envision cell-based oxygen sensors may find utility in a wide variety of bioprocessing applications.
- ItemA core microbiome associated with the peritoneal tumors of pseudomyxoma peritonei(Springer Nature, 2013-07-12) Gilbreath, Jeremy J; Semino-Mora, Cristina; Friedline, Christopher J; Liu, Hui; Bodi, Kip L; McAvoy, Thomas J; Francis, Jennifer; Nieroda, Carol; Sardi, Armando; Dubois, Andre; Lazinski, David W; Camilli, Andrew; Testerman, Traci L; Merrell, D ScottPseudomyxoma peritonei (PMP) is a malignancy characterized by dissemination of mucus-secreting cells throughout the peritoneum. This disease is associated with significant morbidity and mortality and despite effective treatment options for early-stage disease, patients with PMP often relapse. Thus, there is a need for additional treatment options to reduce relapse rate and increase long-term survival. A previous study identified the presence of both typed and non-culturable bacteria associated with PMP tissue and determined that increased bacterial density was associated with more severe disease. These findings highlighted the possible role for bacteria in PMP disease. To more clearly define the bacterial communities associated with PMP disease, we employed a sequenced-based analysis to profile the bacterial populations found in PMP tumor and mucin tissue in 11 patients. Sequencing data were confirmed by in situ hybridization at multiple taxonomic depths and by culturing. A pilot clinical study was initiated to determine whether the addition of antibiotic therapy affected PMP patient outcome. We determined that the types of bacteria present are highly conserved in all PMP patients; the dominant phyla are the Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. A core set of taxon-specific sequences were found in all 11 patients; many of these sequences were classified into taxonomic groups that also contain known human pathogens. In situ hybridization directly confirmed the presence of bacteria in PMP at multiple taxonomic depths and supported our sequence-based analysis. Furthermore, culturing of PMP tissue samples allowed us to isolate 11 different bacterial strains from eight independent patients, and in vitro analysis of subset of these isolates suggests that at least some of these strains may interact with the PMP-associated mucin MUC2. Finally, we provide evidence suggesting that targeting these bacteria with antibiotic treatment may increase the survival of PMP patients. Using 16S amplicon-based sequencing, direct in situ hybridization analysis and culturing methods, we have identified numerous bacterial taxa that are consistently present in all PMP patients tested. Combined with data from a pilot clinical study, these data support the hypothesis that adding antimicrobials to the standard PMP treatment could improve PMP patient survival.
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