Cyclodextrin glycosyltransferase (CGTase) catalyzes intermolecular transglycosylation through either disproportionation or cyclization-coupling pathway. Kinetics analysis reveals that the hesperidin glycosylation process catalyzed by a CGTase variant (M1) is primarily accomplished through the disproportionation pathway. The cyclization-coupling pathway exhibits a lower reaction rate and competitively consumes glycosyl donor and yield byproducts that impair disproportionation. Under the guidance of reaction kinetics, mutagenesis was targeted at residues in the −3, +1, and +2 subsites, known to control the selectivity between disproportionation and cyclization. A quadruple variant was identified with 2.9 times hesperidin glycosylation activity compared to M1, and 20.3 times compared to the wild-type. Kinetic analysis reveals a fourfold improvement of kcat/KmA for disproportionation and an 85.5% reduction in kcat/Km for cyclization after mutagenesis. Binding free energy analysis further confirms that the mutagenesis favors the binding of hesperidin, and destabilizes the binding of cyclodextrin.
{"title":"Kinetics guided engineering of cyclodextrin glycosyltransferase with enhanced intermolecular transglycosylation activity","authors":"Hanchi Chen, Lingjun Ju, Yangyang Dong, Shijie Lu, Yingling Bao, Linjiang Zhu, Xiaolong Chen","doi":"10.1002/aic.18512","DOIUrl":"https://doi.org/10.1002/aic.18512","url":null,"abstract":"Cyclodextrin glycosyltransferase (CGTase) catalyzes intermolecular transglycosylation through either disproportionation or cyclization-coupling pathway. Kinetics analysis reveals that the hesperidin glycosylation process catalyzed by a CGTase variant (M1) is primarily accomplished through the disproportionation pathway. The cyclization-coupling pathway exhibits a lower reaction rate and competitively consumes glycosyl donor and yield byproducts that impair disproportionation. Under the guidance of reaction kinetics, mutagenesis was targeted at residues in the −3, +1, and +2 subsites, known to control the selectivity between disproportionation and cyclization. A quadruple variant was identified with 2.9 times hesperidin glycosylation activity compared to M1, and 20.3 times compared to the wild-type. Kinetic analysis reveals a fourfold improvement of <i>k</i><sub>cat</sub>/<i>K</i><sub>mA</sub> for disproportionation and an 85.5% reduction in <i>k</i><sub>cat</sub>/<i>K</i><sub>m</sub> for cyclization after mutagenesis. Binding free energy analysis further confirms that the mutagenesis favors the binding of hesperidin, and destabilizes the binding of cyclodextrin.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141329723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ionic liquid (IL) can not only serve as solvents to reduce carbon capture energy consumption, but also may activate the CO2 absorption of amine solutions. Here, the absorption mechanism and kinetic modeling of IL-activated single and mixed amines were studied in wetted wall column. N-(2-aminoethyl) ethanolamine (AEEA) and N,N-diethylethanolamine (DEEA) were used as representatives to evaluate the IL activation effects on primary and tertiary amines. It was found that IL activated the reaction process of primary amine, but had no activation effect on tertiary amine. The activation energy of AEEA-IL-CO2 was 22.2 kJ/mol, which was 21.0% lower than AEEA-CO2. Kinetic modeling of IL-activated AEEA and mixed amines was established. Besides, the density functional theory calculations showed that IL can form hydrogen bonding and other interactions with AEEA and CO2 to activate the absorption reaction, which can reduce 29.3% activation energy during the zwitterion formation stage.
离子液体（IL）不仅可以作为溶剂降低碳捕集能耗，还可以激活胺溶液对二氧化碳的吸收。本文研究了在湿润壁柱中离子液体活化单一胺和混合胺的吸收机理和动力学模型。以 N-（2-氨基乙基）乙醇胺（AEEA）和 N,N-二乙基乙醇胺（DEEA）为代表，评估了 IL 对伯胺和叔胺的活化作用。结果发现，IL 能激活伯胺的反应过程，但对叔胺没有激活作用。AEEA-IL-CO2 的活化能为 22.2 kJ/mol，比 AEEA-CO2 低 21.0%。建立了 IL 活化 AEEA 和混合胺的动力学模型。此外，密度泛函理论计算表明，IL 能与 AEEA 和 CO2 形成氢键及其他相互作用来激活吸收反应，从而在形成齐聚物阶段降低 29.3% 的活化能。
{"title":"CO2 absorption mechanism and kinetic modeling of mixed amines with ionic liquid activation","authors":"Rui-Qi Jia, Qing Wu, Liang-Liang Zhang, Bo Zhang, Guang-Wen Chu, Jian-Feng Chen","doi":"10.1002/aic.18493","DOIUrl":"https://doi.org/10.1002/aic.18493","url":null,"abstract":"Ionic liquid (IL) can not only serve as solvents to reduce carbon capture energy consumption, but also may activate the CO<sub>2</sub> absorption of amine solutions. Here, the absorption mechanism and kinetic modeling of IL-activated single and mixed amines were studied in wetted wall column. N-(2-aminoethyl) ethanolamine (AEEA) and N,N-diethylethanolamine (DEEA) were used as representatives to evaluate the IL activation effects on primary and tertiary amines. It was found that IL activated the reaction process of primary amine, but had no activation effect on tertiary amine. The activation energy of AEEA-IL-CO<sub>2</sub> was 22.2 kJ/mol, which was 21.0% lower than AEEA-CO<sub>2</sub>. Kinetic modeling of IL-activated AEEA and mixed amines was established. Besides, the density functional theory calculations showed that IL can form hydrogen bonding and other interactions with AEEA and CO<sub>2</sub> to activate the absorption reaction, which can reduce 29.3% activation energy during the zwitterion formation stage.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141329627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Si Li, Zhixuan Wang, Mingtao Zhang, Lina Zhou, Weiwei Tang, Junbo Gong
Concomitant polymorphs routinely observed in fine chemical industry could impact product purity and consistency; however, both molecular mechanism and process kinetics of concomitant crystallization remain elusive. Herein, we developed a population balance model to understand process kinetics of concomitantly dipolymorphic crystallization using DL-methionine as a model compound. Kinetic parameters were estimated from induction time measurements and unseeded crystallization experiments. Experimental and simulation results demonstrate that the stable β form has a comparable nucleation rate with α form thanks to their close nucleation barrier leading to the concurrent nucleation. Several solution chemistry techniques were utilized to examine the speciation of solute molecules, together revealing the solutes' self-association and the formation of micelle-like aggregates driven by hydrophobic interactions, not hydrogen bonds. These aggregates show dynamic nature against conventional thoughts of classical nucleation kinetics. Finally, the molecular mechanism of concomitant crystallization was uncovered and the implications for polymorph selection and control were discussed.
{"title":"Mechanism and kinetic modeling study on the crystallization of concomitant polymorphs","authors":"Si Li, Zhixuan Wang, Mingtao Zhang, Lina Zhou, Weiwei Tang, Junbo Gong","doi":"10.1002/aic.18516","DOIUrl":"https://doi.org/10.1002/aic.18516","url":null,"abstract":"Concomitant polymorphs routinely observed in fine chemical industry could impact product purity and consistency; however, both molecular mechanism and process kinetics of concomitant crystallization remain elusive. Herein, we developed a population balance model to understand process kinetics of concomitantly dipolymorphic crystallization using DL-methionine as a model compound. Kinetic parameters were estimated from induction time measurements and unseeded crystallization experiments. Experimental and simulation results demonstrate that the stable <i>β</i> form has a comparable nucleation rate with <i>α</i> form thanks to their close nucleation barrier leading to the concurrent nucleation. Several solution chemistry techniques were utilized to examine the speciation of solute molecules, together revealing the solutes' self-association and the formation of micelle-like aggregates driven by hydrophobic interactions, not hydrogen bonds. These aggregates show dynamic nature against conventional thoughts of classical nucleation kinetics. Finally, the molecular mechanism of concomitant crystallization was uncovered and the implications for polymorph selection and control were discussed.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141329541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Keju An, Kai Li, Cheng-Min Yang, Jamieson Brechtl, Diana Stamberga, Mingkan Zhang, Kashif Nawaz
Direct air capture (DAC) is a negative emission technology for removing CO2 from the atmosphere to maintain the CO2 level within a reasonable range so as to address greenhouse effects. In this study, the operational optimization of lab-scale DAC has been investigated using a crossflow air-liquid contactor loaded with a three dimensionally printed Gyroid packing structure and a potassium sarcosinate solvent. The effects of various parameters, including feed air flow rate, liquid solvent flow rate, contactor geometry, and ambient temperature, are examined. The results demonstrate that the Gyroid packing design achieves comparable CO2 capture performance to conventional packed beds but with a significantly lower pressure drop of up to 77.8%, suggesting its potential as an efficient and cost-effective solution for gas–liquid contactors in DAC. Additionally, the study explores the climate impact on CO2 capture performance and finds that as the air temperature increases from 35 to 95°F at a fixed relative humidity of 80%, the CO2 capture rate increased from 23.2% to 46.8% with better stability. The research highlights the importance of optimizing contactor design and operational conditions to improve the CO2 capture rate and feasibility of DAC systems as a negative emission technology for addressing greenhouse effects.
{"title":"Direct air capture with amino acid solvent: Operational optimization using a crossflow air-liquid contactor","authors":"Keju An, Kai Li, Cheng-Min Yang, Jamieson Brechtl, Diana Stamberga, Mingkan Zhang, Kashif Nawaz","doi":"10.1002/aic.18429","DOIUrl":"https://doi.org/10.1002/aic.18429","url":null,"abstract":"Direct air capture (DAC) is a negative emission technology for removing CO<sub>2</sub> from the atmosphere to maintain the CO<sub>2</sub> level within a reasonable range so as to address greenhouse effects. In this study, the operational optimization of lab-scale DAC has been investigated using a crossflow air-liquid contactor loaded with a three dimensionally printed Gyroid packing structure and a potassium sarcosinate solvent. The effects of various parameters, including feed air flow rate, liquid solvent flow rate, contactor geometry, and ambient temperature, are examined. The results demonstrate that the Gyroid packing design achieves comparable CO<sub>2</sub> capture performance to conventional packed beds but with a significantly lower pressure drop of up to 77.8%, suggesting its potential as an efficient and cost-effective solution for gas–liquid contactors in DAC. Additionally, the study explores the climate impact on CO<sub>2</sub> capture performance and finds that as the air temperature increases from 35 to 95°F at a fixed relative humidity of 80%, the CO<sub>2</sub> capture rate increased from 23.2% to 46.8% with better stability. The research highlights the importance of optimizing contactor design and operational conditions to improve the CO<sub>2</sub> capture rate and feasibility of DAC systems as a negative emission technology for addressing greenhouse effects.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141329544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yash A. Kadakia, Fahim Abdullah, Aisha Alnajdi, Panagiotis D. Christofides
This article proposes a two-layer framework to maximize economic performance through dynamic process economics optimization while addressing fluctuating real-world economics and enhancing cyberattack resilience via encryption in the feedback control layer for nonlinear processes. The upper layer employs a Lyapunov-based economic model predictive control scheme, receiving updated economic information for each operating period, while the lower layer utilizes an encrypted linear feedback control system. Encrypted state information is decrypted in the upper layer to determine the economically optimal dynamic operating trajectory through nonlinear optimization. Conversely, the lower layer securely tracks this trajectory in an encrypted space without decryption. To mitigate the cyber vulnerability of the upper layer, we integrate a cyberattack detector that utilizes sensor-derived data for attack detection. We quantify the errors stemming from quantization, disturbances, and sample-and-hold controller implementation. Simulation results of a nonlinear chemical process highlight the robustness and economic benefits of this new control architecture.
{"title":"Integrating dynamic economic optimization and encrypted control for cyber-resilient operation of nonlinear processes","authors":"Yash A. Kadakia, Fahim Abdullah, Aisha Alnajdi, Panagiotis D. Christofides","doi":"10.1002/aic.18509","DOIUrl":"https://doi.org/10.1002/aic.18509","url":null,"abstract":"This article proposes a two-layer framework to maximize economic performance through dynamic process economics optimization while addressing fluctuating real-world economics and enhancing cyberattack resilience via encryption in the feedback control layer for nonlinear processes. The upper layer employs a Lyapunov-based economic model predictive control scheme, receiving updated economic information for each operating period, while the lower layer utilizes an encrypted linear feedback control system. Encrypted state information is decrypted in the upper layer to determine the economically optimal dynamic operating trajectory through nonlinear optimization. Conversely, the lower layer securely tracks this trajectory in an encrypted space without decryption. To mitigate the cyber vulnerability of the upper layer, we integrate a cyberattack detector that utilizes sensor-derived data for attack detection. We quantify the errors stemming from quantization, disturbances, and sample-and-hold controller implementation. Simulation results of a nonlinear chemical process highlight the robustness and economic benefits of this new control architecture.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141304640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The protonic ceramic fuel cells (PCFCs) can convert the chemical energy of fuel directly into electric power, with the advantages of high efficiency and alternative fuel range at intermediate temperatures. Ammonia has been regarded as a promising fuel for PCFCs due to its carbon-free and hydrogen-rich properties, high volumetric energy density and easy storage/transportation. However, the performance of ammonia PCFCs (NH3-PCFCs) is far inferior to the hydrogen PCFCs (H2-PCFCs) because of the sluggish and complex kinetics at anodes. In this study, we established an elementary reaction kinetic model for NH3-PCFCs, investigated the effect of reaction parameters, anode components and reaction partition, and explored the coupling mechanism between the ammonia decomposition and electrochemical reaction. Importantly, the ammonia decomposition and electrochemical reaction can be flexibly regulated by adjusting anode parameters, then affecting the performance ratio of NH3-PCFCs and H2-PCFCs. The detailed rate-determining steps were further identified by experimental and model analysis. Thus, the ammonia/hydrogen performance ratio of the cell can exceed 95% at 550°C after accelerating the ammonia decomposition reaction. Our work provides insights into the kinetics in NH3-PCFCs for improving their performance with optimization.
{"title":"Insight into the complex ammonia decomposition/oxidation kinetics in ammonia protonic ceramic fuel cells via elementary modeling","authors":"Jiacheng You, Jiangping Chen, Shunli Liu, Huihuang Fang, Fulan Zhong, Yu Luo, Lilong Jiang","doi":"10.1002/aic.18497","DOIUrl":"https://doi.org/10.1002/aic.18497","url":null,"abstract":"The protonic ceramic fuel cells (PCFCs) can convert the chemical energy of fuel directly into electric power, with the advantages of high efficiency and alternative fuel range at intermediate temperatures. Ammonia has been regarded as a promising fuel for PCFCs due to its carbon-free and hydrogen-rich properties, high volumetric energy density and easy storage/transportation. However, the performance of ammonia PCFCs (NH<sub>3</sub>-PCFCs) is far inferior to the hydrogen PCFCs (H<sub>2</sub>-PCFCs) because of the sluggish and complex kinetics at anodes. In this study, we established an elementary reaction kinetic model for NH<sub>3</sub>-PCFCs, investigated the effect of reaction parameters, anode components and reaction partition, and explored the coupling mechanism between the ammonia decomposition and electrochemical reaction. Importantly, the ammonia decomposition and electrochemical reaction can be flexibly regulated by adjusting anode parameters, then affecting the performance ratio of NH<sub>3</sub>-PCFCs and H<sub>2</sub>-PCFCs. The detailed rate-determining steps were further identified by experimental and model analysis. Thus, the ammonia/hydrogen performance ratio of the cell can exceed 95% at 550°C after accelerating the ammonia decomposition reaction. Our work provides insights into the kinetics in NH<sub>3</sub>-PCFCs for improving their performance with optimization.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141299238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jia-Xin Du, Bo Liang, Xing-Ming Zhao, Chong Sha, Aihua Liu, Yang-Chun Yong
Chemical-to-bioelectricity by using different biocatalysts was considered as a next-generation green power source. However, bioelectricity production using macromolecular substrate usually encountered low Coulombic efficiency (CE) and power density due to inefficient electron releasing and sluggish electron collection. Here, a rationally engineered biocascade (including depolymerization module, fermentation module, and electro-respiration module) embedded in highly conductive 3D graphene hydrogel (electron collection module) was designed and fabricated as a modular platform to simultaneously improve the substrate degradation, enhance the electron releasing and reinforce the electron collection. As a result, this modular platform enabled a ~15-fold improvement on power density and reached the highest CE (46.3%) and power density (780 mW/m2) ever reported for bioelectricity production from starch (a model macromolecular substrate). This work demonstrated a promising approach for rationally harvesting bioelectricity with complicated substrates, which would open up a new avenue for practical applications.
利用不同的生物催化剂进行化学转化生物发电被认为是下一代绿色能源。然而，由于电子释放效率低和电子收集缓慢，利用大分子基质生产生物电通常会遇到库仑效率（CE）和功率密度低的问题。在此，我们设计并制造了一个嵌入高导电性三维石墨烯水凝胶（电子收集模块）的模块化平台，合理设计了生物级联（包括解聚模块、发酵模块和电呼吸模块），以同时改善基质降解、提高电子释放和加强电子收集。因此，该模块化平台使功率密度提高了约 15 倍，达到了迄今为止利用淀粉（一种示范性大分子基质）生产生物电的最高 CE 值（46.3%）和功率密度（780 mW/m2）。这项工作展示了一种利用复杂基质合理获取生物电的可行方法，为实际应用开辟了一条新途径。
{"title":"Rational design of graphene biohydrogel as a modular platform for highly efficient starch-to-bioelectricity","authors":"Jia-Xin Du, Bo Liang, Xing-Ming Zhao, Chong Sha, Aihua Liu, Yang-Chun Yong","doi":"10.1002/aic.18507","DOIUrl":"https://doi.org/10.1002/aic.18507","url":null,"abstract":"Chemical-to-bioelectricity by using different biocatalysts was considered as a next-generation green power source. However, bioelectricity production using macromolecular substrate usually encountered low Coulombic efficiency (CE) and power density due to inefficient electron releasing and sluggish electron collection. Here, a rationally engineered biocascade (including depolymerization module, fermentation module, and electro-respiration module) embedded in highly conductive 3D graphene hydrogel (electron collection module) was designed and fabricated as a modular platform to simultaneously improve the substrate degradation, enhance the electron releasing and reinforce the electron collection. As a result, this modular platform enabled a ~15-fold improvement on power density and reached the highest CE (46.3%) and power density (780 mW/m<sup>2</sup>) ever reported for bioelectricity production from starch (a model macromolecular substrate). This work demonstrated a promising approach for rationally harvesting bioelectricity with complicated substrates, which would open up a new avenue for practical applications.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141299223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anita L. Ziegler, Ashutosh Manchanda, Marc-Daniel Stumm, Lars M. Blank, Alexander Mitsos
Constraint-based optimization of microbial strains and model-based bioprocess design have been used extensively to enhance yields in biotechnological processes. However, strain and process optimization are usually carried out in sequential steps, causing underperformance of the biotechnological process when scaling up to industrial fermentation conditions. Herein, we propose the optimization formulation SimulKnock that combines the optimization of a fermentation process with metabolic network design in a bilevel optimization program. The upper level maximizes space-time yield and includes mass balances of a continuous fermentation, while the lower level is based on flux balance analysis. SimulKnock predicts optimal gene deletions and finds the optimal trade-off between growth rate and product yield. Results of a case study with a genome-scale metabolic model of Escherichia coli indicate higher space-time yields than a sequential approach using OptKnock for almost all target products considered. By leveraging SimulKnock, we reduce the gap between strain and process optimization.
{"title":"Simultaneous design of fermentation and microbe","authors":"Anita L. Ziegler, Ashutosh Manchanda, Marc-Daniel Stumm, Lars M. Blank, Alexander Mitsos","doi":"10.1002/aic.18501","DOIUrl":"https://doi.org/10.1002/aic.18501","url":null,"abstract":"Constraint-based optimization of microbial strains and model-based bioprocess design have been used extensively to enhance yields in biotechnological processes. However, strain and process optimization are usually carried out in sequential steps, causing underperformance of the biotechnological process when scaling up to industrial fermentation conditions. Herein, we propose the optimization formulation <i>SimulKnock</i> that combines the optimization of a fermentation process with metabolic network design in a bilevel optimization program. The upper level maximizes space-time yield and includes mass balances of a continuous fermentation, while the lower level is based on flux balance analysis. SimulKnock predicts optimal gene deletions and finds the optimal trade-off between growth rate and product yield. Results of a case study with a genome-scale metabolic model of <i>Escherichia coli</i> indicate higher space-time yields than a sequential approach using OptKnock for almost all target products considered. By leveraging SimulKnock, we reduce the gap between strain and process optimization.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141299236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dhairya R. Vyas, Song Gao, Paul B. Umbanhowar, Julio M. Ottino, Richard M. Lueptow
Static granular packings play a central role in numerous industrial applications and natural settings. In these situations, fluid or fine particle flow through a bed of static particles is heavily influenced by the narrowest passage connecting the pores of the packing, commonly referred to as pore throats, or constrictions. Existing studies predominantly assume monodisperse rigid particles, but this is an oversimplification of the problem. In this work, we illustrate the connection between pore throat size, polydispersity, and particle deformation in a packed bed of spherical particles. Simple analytical expressions are provided to link these properties of the packing, followed by examples from Discrete Element Method (DEM) simulations of fine particle percolation demonstrating the impact of polydispersity and particle deformation. Our intent is to emphasize the substantial impact of polydispersity and particle deformation on constriction size, underscoring the importance of accounting for these effects in particle transport in granular packings.
{"title":"Impacts of packed bed polydispersity and deformation on fine particle transport","authors":"Dhairya R. Vyas, Song Gao, Paul B. Umbanhowar, Julio M. Ottino, Richard M. Lueptow","doi":"10.1002/aic.18499","DOIUrl":"https://doi.org/10.1002/aic.18499","url":null,"abstract":"Static granular packings play a central role in numerous industrial applications and natural settings. In these situations, fluid or fine particle flow through a bed of static particles is heavily influenced by the narrowest passage connecting the pores of the packing, commonly referred to as pore throats, or constrictions. Existing studies predominantly assume monodisperse rigid particles, but this is an oversimplification of the problem. In this work, we illustrate the connection between pore throat size, polydispersity, and particle deformation in a packed bed of spherical particles. Simple analytical expressions are provided to link these properties of the packing, followed by examples from Discrete Element Method (DEM) simulations of fine particle percolation demonstrating the impact of polydispersity and particle deformation. Our intent is to emphasize the substantial impact of polydispersity and particle deformation on constriction size, underscoring the importance of accounting for these effects in particle transport in granular packings.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The second-law analysis evaluates the irreversibilities of a process. Systematic study of the relationship between thermodynamic efficiency and process modifications enhances process synthesis. The Allam cycle is an oxy-fuel combustion cycle with nearly complete carbon capture that offers greater efficiency than current electricity generating systems. This study applies lost work analysis to the original Allam cycle and three modifications to obtain the distribution of irreversibilities and the effects of different configurations among potential process improvements for more sustainable power generation. The major inefficiencies are from the combustors and heat exchangers. We also examine the economic profitability of the alternatives. The largest equipment costs are for the turbines, compressors, and recuperators. We find that improving efficiency leads to less economic return; a configuration with partial compression has the highest efficiency, while the original Allam cycle has the highest profitability. We discuss how to resolve this apparent conflict between sustainability and profitability.
{"title":"Thermoeconomic analysis of sCO2 power cycles","authors":"Duoli Chen, John P. O'Connell, Warren D. Seider","doi":"10.1002/aic.18502","DOIUrl":"https://doi.org/10.1002/aic.18502","url":null,"abstract":"The second-law analysis evaluates the irreversibilities of a process. Systematic study of the relationship between thermodynamic efficiency and process modifications enhances process synthesis. The Allam cycle is an oxy-fuel combustion cycle with nearly complete carbon capture that offers greater efficiency than current electricity generating systems. This study applies lost work analysis to the original Allam cycle and three modifications to obtain the distribution of irreversibilities and the effects of different configurations among potential process improvements for more sustainable power generation. The major inefficiencies are from the combustors and heat exchangers. We also examine the economic profitability of the alternatives. The largest equipment costs are for the turbines, compressors, and recuperators. We find that improving efficiency leads to less economic return; a configuration with partial compression has the highest efficiency, while the original Allam cycle has the highest profitability. We discuss how to resolve this apparent conflict between sustainability and profitability.","PeriodicalId":120,"journal":{"name":"AIChE Journal","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141251958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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