An extracellular stochastic model of early HIV infection and the formulation of optimal treatment policy

The problem of scheduling optimal treatment strategies for patients at the early stage of human immunodeficiency virus (HIV) infection is investigated. Unlike patients with an established HIV infection, complete eradication of the infection is still possible at this stage and treatment can further increase the probability of eradication. However, high dosages of drugs should be avoided, if possible, because of toxic side effects. Stochastic simulation is capable of determining the infection establishment probability at the early infection stage. Consequently, to obtain acceptable treatment strategies, an optimization problem was formulated, employing a stochastic model to predict the response of an average patient to treatment. Optimal treatment strategies for prompt and also a few days latency in treatment initiation were computed. These strategies were compared with constant treatment strategies and were shown to be more beneficial in silico, i.e., they either decreased the infection establishment probability or the dosage of the drugs.     

Experimental Validation of a Fundamental Model for PCR Efficiency

Recently a theoretical analysis of PCR efficiency has been published by Booth et al. (2010). The PCR yield is the product of three efficiencies: (i) the annealing efficiency is the fraction of templates that form binary complexes with primers during annealing, (ii) the polymerase binding efficiency is the fraction of binary complexes that bind to polymerase to form ternary complexes and (iii) the elongation efficiency is the fraction of ternary complexes that extend fully. Yield is controlled by the smallest of the three efficiencies and control could shift from one type of efficiency to another over the course of a PCR experiment. Experiments have been designed that are specifically controlled by each one of the efficiencies and the results are consistent with the mathematical model. The experimental data has also been used to quantify six key parameters of the theoretical model. An important application of the fully characterized model is to calculate initial template concentration from real-time PCR data. Given the PCR protocol, the midpoint cycle number (where the template concentration is half that of the final concentration) can be theoretically determined and graphed for a variety of initial DNA concentrations. Real-time results can be used to calculate the midpoint cycle number and consequently the initial DNA concentration, using this graph. The application becomes particularly simple if a conservative PCR protocol is followed where only the annealing efficiency is controlling.     

Adaptation of Dynamic Data-Driven Models for Real-Time Applications: From Simulated to Real Batch Distillation Trajectories by Transfer Learning

In the absence of knowledge about challenging dynamic phenomena involved in batch distillation processes, e.g., complex flow regimes or appearing and vanishing phases, generation of accurate mechanistic models is limited. Real plant data containing this missing information is scarce, also limiting the use of data-driven models. To exploit the information contained in measurement data and a related but inaccurate first-principles model, transfer learning from simulated to real plant data is analyzed. For the use case of a batch distillation column, the adapted model provides more accurate predictions than a data-driven model trained exclusively on scarce real plant data or simulated data. Its enhanced convergence and lower computational cost make it suitable for optimization in real-time.     

Effect of endogenous hydrogen utilization on improved methane production in an integrated microbial electrolysis cell and anaerobic digestion: Employing catalyzed stainless steel mesh cathode

Improving the production of methane,while maintaining a significant level of process stability,is the main challenge in the anaerobic digestion process.Recently,microbial electrolysis cell (MEC) has become a promising method for CO2 reduction produced during anaerobic digestion (AD) and leads to minimize the cost of biogas upgrading technology.In this study,the MEC-AD coupled reactor was used to generate and utilize the endogenous hydrogen by employing biocompatible electrodeposited cobalt-phosphate as catalysts to improve the performance of stainless steel mesh and carbon cloth electrodes.In addition,the modified version of ADM1 model (ADM1da) was used to simulate the process.The result indicated that the MEC-AD coupled reactor can improve the CH4 yield and production rate significantly.The CH4 yield was enhanced with an average of 48％ higher than the control.The CH4 production rate was also increased 1.65 times due to the utilization of endogenous hydrogen.The specific yield,flow rate,content of CH4,and pH value were the variables that the model was best at predicting (with indexes of agreement:0.960/0.941,0.682/0.696,0.881/0.865,and 0.764/0.743) of the process with SS-meshes 80/SS-meshes 200,respectively.Employing the catalyzed SS mesh cathode,in the MEC-AD coupled reactor,could be an effective approach to generate and facilitate the utilization of endogenous hydrogen in anaerobic digestion of CH4 production technology,which is a promising and feasible method to scale up to the industrial level.     

Intensification of chemical separation engineering by nanostructured channels and nanofluidics: From theories to applications

With the development of manufacturing technology on the nanoscale, the precision of nano-devices is rapidly increasing with lower cost. Different from macroscale or microscale fluids, many specific phenomena and advantages are observed in nanofluidics. Devices and process involving and utilizing these phenomena play an important role in many fields in chemical engineering including separation, chemical analysis and transmission.In this article, we summarize the state-of-the-art progress in theoretical studies and manufacturing technologies on nanofluidics. Then we discuss practical applications of nanofluidics in many chemical engineering fields,especially in separation and encountering problems. Finally, we are looking forward to the future of nanofluidics and believe it will be more important in the separation process and the modern chemical industry.     

Bipolar membrane electrodialysis for clean production of L-10-camphorsulfonic acid: From laboratory to industrialization

In this study, bipolar membrane electrodialysis (BMED) was implemented for cleaner production of L-10-camphorsulfonic acid (L-CSA) to lower the environmental impact. Under the current density of 300–400 A/m² and feed salt concentration of 6–10 wt.%, the energy consumption and current efficiency were 2.24–2.70 kWh/kg and 20.89–29.5%, respectively. Positron annihilation lifetime spectroscopy, x-ray photoelectron spectroscopy with ion beam etching, and other characterizations were used to elucidate the transport behaviors of large-sized anions across the membranes. It was speculated that the large-sized camphor sulfonate ions were more likely to deposit on the surface of the anion-exchange membrane to form a deposition layer under a direct current electric field. The appearance of water splitting at this deposition layer would offset the water dissociation in the bipolar membrane. Nevertheless, the successful commissioning of industrial-scale stack proved the feasibility and sustainability of BMED technique for a closed loop L-CSA production.     

Biofuel purification in GME zeolitic–imidazolate frameworks: From ab initio calculations to molecular simulations

A multiscale modeling study is reported on the adsorption of ethanol/water in five zeolitic–imidazolate frameworks (ZIFs) for biofuel purification. The ZIFs (ZIF‐68, ?69, ?78, ?79, and ?81) have isoreticular Gmelinite topology but differ in organic linkers. The simulated adsorption isotherms of ethanol and water in ZIF‐68 agree fairly well with experimental data. At a low pressure, ZIF‐78 exhibits the highest uptake due to strong hydrogen‐bonding between ?NO₂ groups and adsorbates. The heats of adsorption at infinite dilution largely follow the trend of binding energies estimated from ab initio calculations. At a high pressure, the uptake is governed primarily by free volume but also affected by hydrogen‐bonding. Among the five ZIFs, ZIF‐79 with hydrophobic ?CH₃ groups shows the highest adsorptive selectivity for ethanol/water mixtures. This study provides microscopic insights into the adsorption and separation of ethanol/water in ZIFs, and would facilitate the development of new ZIFs for biofuel purification. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2763–2775, 2015     

From Molecules to Heat-Integrated Processes: Computer-Aided Design of Solvents and Processes Using Quantum Chemistry

Solvents are key to many chemical and energy conversion processes. Solvents should be selected as part of process design, optimizing a process-level objective to account for the interactions between molecular properties and process performance. In this paper, we integrate the computer-aided molecular design of solvents with the design of heat-integrated processes for minimum utility demand. The process flowsheet is represented by thermodynamically accurate shortcut process models, encompassing the most common unit operations: extraction, distillation, absorption, and multiphase reaction. For each candidate solvent, we optimize the process considering heat integration and design solvents based on their process performance. All thermodynamic properties are predicted using quantum chemistry. The method is applied to two case studies: extraction-distillation and integrated carbon capture and utilization. In both studies, designed solvents improve process performance compared to literature benchmarks, where simpler heuristics lead to suboptimal choices. Thus, the results highlight the importance of integrating molecular and process design to achieve maximum process performance.     

Process systems engineering: From Solvay to modern bio- and nanotechnology.: A history of development, successes and prospects for the future

The term Process Systems Engineering (PSE) is relatively recent. It was coined about 50 years ago at the outset of the modern era of computer-aided engineering. However, the engineering of processing systems is almost as old as the beginning of the chemical industry, around the first half of the 19th century. Initially, the practice of PSE was qualitative and informal, but as time went on it was formalized in progressively increasing degrees. Today, it is solidly founded on engineering sciences and an array of systems-theoretical methodologies and computer-aided tools. This paper is not a review of the theoretical and methodological contributions by various researchers in the area of PSE. Its primary objective is to provide an overview of the history of PSE, i.e. its origin and evolution; a brief illustration of its tremendous impact in the development of modern chemical industry; its state at the turn of the 21st century; and an outline of the role it can play in addressing the societal problems that we face today such as; securing sustainable production of energy, chemicals and materials for the human wellbeing, alternative energy sources, and improving the quality of life and of our living environment. PSE has expanded significantly beyond its original scope, the continuous and batch chemical processes and their associated process engineering problems. Today, PSE activities encompass the creative design, operation, and control of: biological systems (prokaryotic and eukaryotic cells); complex networks of chemical reactions; free or guided self-assembly processes; micro- and nano-scale processes; and systems that integrate engineered processes with processes driven by humans, legal and regulatory institutions. Through its emphasis on synthesis problems, PSE provides the dialectic complement to the analytical bent of chemical engineering science, thus establishing the healthy tension between synthesis and analysis, the foundation of any thriving discipline. As a consequence, throughout this paper PSE emerges as the foundational underpinning of modern chemical engineering; the one that ensures the discipline's cohesiveness in the years to come.     

Multiscale modeling of methane catalytic partial oxidation: From the mesopore to the full‐scale reactor operation

A multiscale methodology combining three different reactor length‐scales is presented to investigate the role of the catalyst internal pore structure and metal loading and dispersion on the catalyst layer and full‐scale reactor performances. At the catalyst level, the methodology involves pore‐scale simulations in the three‐dimensional mesopore and macropore space. The information gathered at the catalyst level is delivered to the full‐scale reactor model. The methodology is applied to a honeycomb reactor performing methane partial oxidation considering reaction kinetics described through a detailed multistep reaction mechanism. Realistic mesopore and macropore structures were reconstructed and combined to form specific bidisperse porous washcoat layers. The study shows that species effective diffusivities vary significantly but not in the same proportion for different structures. For structures featuring poor transport characteristics, the integral methane conversion and hydrogen selectivity are strongly affected while the reactor temperatures increase substantially. © 2017 American Institute of Chemical Engineers AIChE J, 64: 578–594, 2018     

Indirect urea electrooxidation by nickel(III) in alkaline medium: From kinetic and mechanism to reactor modeling

This study consists in the determination of two kinetic laws of urea oxidation (UO) and electrooxidation (UEO) in alkaline media on nickel(III). Two kinds of active sites were examined, the first one derived from a Ni(OH)₂ powder and the second from a massive nickel electrode. Partial orders of nickel(III) (two for UO and five UEO) enable to conclude about (i) the urea adsorption on two nickel(III) sites and (ii) that a multistep oxidation of urea occurs involving five nickel(III) site electroregenerations. A multipathway mechanism is also proposed to explain UEO facilitated by the nickel(III)/nickel(II) mediation system, and to predict the by-products' formation previously identified ($\mathrm{N}{\mathrm{O}}_2^{-},\mathrm{N}{\mathrm{H}}_3,\mathrm{OC}{\mathrm{N}}^{-},\mathrm{C}{\mathrm{O}}_3^{2-}$). At last, a model combining the UEO kinetic law previously established, with diffusive and convective transport phenomena was developed. A consistent correlation (maximum deviation of 6%) between laboratory electrolysis results with the model' predictions was obtained under different operating conditions, enabling the validation of this model.