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Process intensification is crucial for industrial implementation of biocatalysis and can be achieved by continuous process operation in miniaturized reactors with efficiently immobilized biocatalysts, enabling their long-term use. Due to their extremely large surface-to-volume ratio, nanomaterials are promising supports for enzyme immobilization. In this work, different functionalized nanofibrous nonwoven membranes were embedded in a two-plate microreactor to enable immobilization of hexahistidine (His 6)-tagged amine transaminases (ATAs) in flow. A membrane coated with Cu2+ ions gave the best results regarding His 6 -tagged ATAs immobilization among the membranes tested yielding an immobilization yield of up to 95.3 % for the purified N -His 6 -ATA-wt enzyme. Moreover, an efficient one-step enzyme immobilization process from overproduced enzyme in Escherichia coli cell lysate was developed and yielded enzyme loads up to 1088 U mL−1. High enzyme loads resulted in up to 80 % yields of acetophenone produced from 40 mM (S)-α-methylbenzylamine in less than 4 min using a continuously operated microreactor. Up to 81 % of the initial activity was maintained in a 5-day continuous microreactor operation with immobilized His 6 -tagged ATA constructs. The highest turnover number within the indicated time was 7.23·106, which indicates that this immobilization approach using advanced material and reactor system is highly relevant for industrial implementation. [Display omitted] • A microreactor with nonwoven nanofiber membrane was developed. • Nanofibers with various functional groups were tested for enzyme immobilization. • His6-tagged amine transaminase was immobilized on membranes with metal ions. • One-step purification and immobilization with very high enzyme loads was reached. • Long-term stability of microreactor system and high turnover numbers were obtained. [ABSTRACT FROM AUTHOR]

Background: Vildagliptin (VLG), an antidiabetic agent, presents a potential solution to this widespread affliction. It exhibits notable attributes, such as a high solubility and a shorter elimination half-life. The current study uses a microreactor to fabricate sustained-release VLG-encapsulated cross-linked chitosan–dextran sulfate nanoparticles (VLG-CDNPs). The fabrication was systematically optimized using the design of experiment approach. Results: The optimized VLG-CDNPs had an average particle size of 217.4 ± 12.3 nm and an encapsulation efficiency of 78.25 ± 3.0%. Scanning electron microscopy revealed that the nanoparticles had a smooth spherical shape. Spray drying was used for drying, and the reconstitution ability was close to ideal (~ 1.33). In vitro studies revealed sustained VLG release over 12 h, with ~ 58% in acidic and ~ 83% in basic conditions. Cell viability remained at 80% even at 100 μg/mL, and glucose uptake in L6 cells was significantly enhanced with VLG-CDNPs (78.34%) compared to pure VLG (60.91%). VLG-CDNPs also showed moderate inhibitory activity against α-amylase (41.57%) and α-glucosidase (63.48%) compared to pure VLG, which had higher inhibition levels. Conclusion: The study's outcome suggested that the optimized VLG-CDNPs may serve as an effective and promising nanoformulation for managing diabetes mellitus. [ABSTRACT FROM AUTHOR]

AbstractA multiphysics coupling methodology for heat pipe microreactors is presented in this work that includes a focus on a critical control drum position search routine and burnup capabilities. As the Serpent code is used for neutronics calculations, the recently developed GRsecant method for finding critical control drum positions is employed, which has explicit measures to manage the uncertainty introduced from the Monte Carlo calculation method. This work complements existing multiphysics modeling tools for heat pipe microreactors because it can be used to generate cross sections with fuel compositions determined by depletion with critical control drum positions.These methods are applied to a microreactor design motivated by the eVinciTM heat pipe microreactor. The convergence of the multiphysics coupling routine is analyzed at multiple burnup points. The multiphysics iterations with critical control drum search were observed to converge for all calculations performed in this work. Overall, the multiphysics coupling procedure enables the calculation of both thermal and neutronics characteristics with control drums in their critical positions for the core lifetime. [ABSTRACT FROM AUTHOR]

In order to enhance the efficiency of diphenyldimethoxysilane preparation in microreactors, this study utilized the computational fluid dynamics simulation based on the finite element method to explore the impact of the internal structural parameters of the spiral two-step microreactor (STMR) on the reaction outcomes, with the aim of optimizing its structure for high-performance catalytic reactions. By designing a microreactor based on the Archimedean spiral shape and introducing two ribbed obstacles, the structure was optimized through adjusting the relevant ratios. The effects of different-sized structures and obstacles within the reaction zone and non-reaction zone on the product concentration and reaction results were discussed. The results demonstrate that lower obstacle heights and smaller aspect ratios (P = 2:7, R = 5:6) are beneficial for improving the reaction efficiency and product concentration. This study offers a theoretical foundation for microreactor design and is anticipated to further drive the development of microreactor technology. [ABSTRACT FROM AUTHOR]

A microreactor is a chemical reaction device that mixes liquids in a very narrow channel and continuously generates reactions. They are attracting attention as next-generation chemical reaction devices because of their ability to achieve small-scale and highly efficient reactions compared to the conventional badge method. However, the challenge is to design a control system that is tolerant of faults in some of the enormous number of sensors in order to achieve parallel production by numbering up. In a previous study, a simultaneous control system for two different temperatures was proposed in an experimental system that imitated the microreactor cooled by Peltier devices. In addition, a fault-tolerant control system for one area has also been proposed. However, the fault-tolerant control system could not be applied to the control system of two temperatures in the previous study. In this paper, we extend it to a two-input, two-output fault-tolerant control system. We also use a fault detection system that combines ChangeFinder, a time-series data analysis method, and One-Class SVM, an unsupervised learning method. Finally, the effectiveness of the proposed method is confirmed by experiments. [ABSTRACT FROM AUTHOR]

Herein, the first photochemical microscale continuous oscillatory baffled reactor, that is, Photo‐μCOBR, was designed and evaluated. Computational fluid dynamics simulations were used to optimize the key structural parameter and operating conditions. Then, the mixing process was simulated and the μCOBR was shown to be more than 23 times faster than the straight channel both under oscillating conditions. Finally, a glass Photo‐μCOBR was fabricated by femtosecond laser internal engraving technology, and the photocatalytic gas–liquid oxidation of dihydroartemisinic acid was performed. A yield of 65.9% was achieved in a residence time of ~120 s and at a gas–liquid flow rate ratio of 1:3 (vs. 18.6% in the capillary photomicroreactor under identical conditions). The results in this work offer guidelines for the design and operation of microscale COBRs, and the as‐fabricated Photo‐μCOBR displays good potential for gas–liquid photochemical reactions. [ABSTRACT FROM AUTHOR]

Since the concept of microreactor was first proposed in the 1980s, it has been entering the chemistry and chemical engineering fields at a high speed and is favored by both scientific and commercial fields. The development of microreactors has been extensively studied in the literature, but less analysis has been carried out from the perspective of industrial technology. This paper aims to identify, analyze, and map the technological profile of microreactors from the perspective of patents. Based on the text mining techniques, a quantitative analysis of 16,327 microreactor‐related patents in the Derwent Innovations Index database was conducted. The analysis reveals a consistent annual increase in the number of microreactor‐related patents from 1982 to 2021. Specifically, China emerges as the leading country in terms of patent disclosures, whereas the United States and the World Intellectual Property Organization (WIPO) play a crucial role in knowledge transfer. Moreover, this study identifies the technological evolution path for microreactors and analyzes in detail the key patents along this evolution path. Individuation, modularization, and greening are the developing directions of microreactor technology in the future. This research offers valuable guidance for researchers and industry professionals in decision‐making and driving advancements in microreactor technology. [ABSTRACT FROM AUTHOR]

Continuous flow synthesis is pivotal in dye production to address batch‐to‐batch variations. However, synthesizing water‐insoluble dyes in an aqueous system poses a challenge that can lead to clogging. This study successfully achieved the safe and efficient synthesis of azo dyes by selecting and optimizing flow reactor modules for different reaction types in the two‐step reaction and implementing cascade cooperation. Integrating continuous flow microreactor with continuous stirred tank reactor (CSTR) enabled the continuous flow synthesis of Sudan Yellow 3G without introducing water‐soluble functional groups or using organic solvents to enhance solubility. Optimizing conditions (acidity/alkalinity, temperature, residence time) within the initial modular continuous flow reactor resulted in a remarkable 99.5% isolated yield, 98.6 % purity, and a production rate of 2.90 g h−1. Scaling‐up based on different reactor module characteristics further increased the production rate to 74.4 g h−1 while maintaining high yield and purity. The construction of this small 3D‐printing modular cascaded reactor and process scaling‐up provide technical support for continuous flow synthesis of water‐insoluble dyes, particularly high‐market‐share azo dyes. Moreover, this versatile methodology proves applicable to continuous flow processes involving various homogeneous and heterogeneous reaction cascades. [ABSTRACT FROM AUTHOR]

In this study, sodium dodecylbenzene sulfonate was used as a stabilizer, and NaOH, TBHP, and benzoyl chloride were used as reactants in the preparation of tert–butyl peroxybenzoate (TBPB) using a two–step process. The process conditions were optimized by a three–factor, three–level Box–Behnken design approach. The results showed that the yield of TBPB achieved 88.93% under the optimum conditions of temperature of 31.50 °C, feeding time of 22.00 min, and NaOH concentration of 15%. The exothermic properties of the synthesis of TBPB were investigated using reaction calorimetry. The thermal decomposition characteristics of reactants and products were analyzed by differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC), and the changes in substance types, characteristic peaks, and exothermic quantities during the reaction were analyzed before and after the reaction by FTIR. The reaction mechanism was proposed by combining EasyMax 102, RC1e, gas chromatography (GC), and Fourier transform infrared spectrometry (FTIR). A comprehensive study of the reaction mechanism and reaction exotherm was carried out using density functional theory (DFT) to predict the reaction energy change and the direction of the reaction and to determine whether the reaction was reversible or not. The risk level for the synthesis of TBPB in semi–batch mode was evaluated using a risk matrix and the Stoessel criticality diagram. The optimal conditions for the TBPB synthesis process in a plate microreactor were explored. Both microreactors and semi–batch modes were comparatively analyzed using the m–ITHI quantitative assessment method. The results indicated a hazard class 2 in semi–batch mode and a hazard class 1 in the microreactor. The results of the study may provide a reference for the further improvement of the intrinsically safe design of the synthetic TBPB process. [ABSTRACT FROM AUTHOR]

The liquid–liquid immiscible flow and mass transfer were investigated in a novel Taylor–Couette microreactor (TCMR). Due to the rotation shear and microscale effects, each phase flowed in the form of helical strips/bands, instead of dispersion droplets as in conventional equipment. Based on the movement and inclination of the bands, the helical vortex (HV), mixed helical vortex (MHV) and stationary helical vortex (SHV) were distinguished. The characteristics of the regimes were strongly influenced by rotation speed and flow rate, but the specific surface area only slightly varied. The flow regimes also influenced the two phase mass transfer. It was shown that the mass transfer coefficient kLa monotonically increased with the rotation speed in the HV regime, while it slightly decreased when the flow shifted into the MHV/SHV regime. According to the parametric studies, empirical correlations were developed for the flow regime transition and mass transfer prediction. [ABSTRACT FROM AUTHOR]

Reduction by one-electron activation or hydrogenation of N2 is extraordinarily difficult because of its extremely stable triple bond and symmetry-forbidden direct H2 addition. Demonstrated herein is reduction or hydrogenation of N2 in perfluorocarbon cage C70F70, a promising nanoreactor with synergetic confinement and electron-catalyzing effects. C70F70 pointing all dipolar C–F units toward its center not only traps reactants but also gives the cage and its guest species strong electron-hosting/binding abilities through lowering their orbital energies. Such a confinement effect can force one electron into the N2 π*-orbital, not only activating the NN bond but also making its frontier molecular orbitals symmetry matching with H2 and thus boosting its hydrogenation with a noticeable lowering of the energy barrier. The ability to initiate reduction reactions by absorbing electrons into the cage-reactor without surface adsorption and solid catalysts enables pathways that are not accessible using conventional electro-/photochemical processes. [ABSTRACT FROM AUTHOR]

Experimental investigations into acoustic cavitation and ultrasound-assited emulsification process between highly viscous liquids were systematically conducted in a laboratory-built ultrasonic microreactor. Under ultrasound irradiation, four cavitation modes were observed simultaneously in soybean oil, including volume, shape, transient collapse and cavitation clouds. Influenced by the intense oscillation of cavitation bubbles, emulsification between viscous liquids was initiated through a dispersion and migration mode. The effects of varying parameters, such as input power, residence time, channel size, HLB value, surfactant concentration and volume ratio between aqueous and oil phase, on the size and polydispersity of prepared emulsion were investigated using water-soybean oil two-phase system as a model. The emulsion size was reduced to 75.60 nm through optimization of experimental parameters. Based on these findings, the ultrasonic microreactor was successfully employed in the preparation of Vitamin E-enriched nano-emulsions. A fine emulsion with low average size (47.69 nm) and good storage stability (60 days) was prepared within 2 min, further indicating the potential application of ultrasonic microreactor in the beverage and pharmaceutical industries. Article Highlights: Emulsification between viscous liquids was realized through a dispersion and migration mode. Effects of varying parameters on size and polydispersity of prepared emulsion were investigated. Vitamin E-enriched nano-emulsion with low average size and good storage stability was prepared within 2 min. [ABSTRACT FROM AUTHOR]

The Pinnick oxidation, due to its tolerance for sensitive functional groups, is widely used in the process of oxidizing α,β-unsaturated aldehydes to corresponding carboxylic acids. The reaction reagents typically include sodium chlorite, buffer salts, and a scavenger. However, the controllability of Pinnick oxidation in the batch reaction process is poor due to the inherent limitations of the reactor's performance. This leads to potential safety risks and necessitates the reaction to proceed slowly under conditions of low temperature and low concentration. In this work, we introduced a new continuous micro-reaction process to intensify the Pinnick oxidation. The water-soluble crotonic acid was selected as a typical object of study. Through the study of reaction parameters and the construction of a micro-reaction system, efficient continuous process was achieved under high-temperature and high-pressure conditions for the first time. Compared to the batch process, the reaction benefited from the superheated condition resulting in a significant acceleration of the reaction rate, efficient gas–liquid interphase mass transfer allowing for effective utilization of the generated chlorine dioxide, and the inherent safety of the microreactor enabling an increase in reaction concentration. In addition, the buffer salts used in the Pinnick oxidation has been successfully replaced by hydrochloric acid and applied to the continuous flow. This work shows the tremendous potential of microreactors in utilizing harsh reaction conditions to achieve process intensification. Article Highlights: A superheated micro-reaction process was introduced into the Pinnick oxidation to achieve efficient and safe preparation of crotonic acid. Efficient gas–liquid interphase mass transfer in microreactor realized effective utilization of the by-product chlorine dioxide. The great replacement of phosphate buffer salts with hydrochloric acid was achieved in continuous flow. [ABSTRACT FROM AUTHOR]

The process of noble metal nanoparticle synthesis is complex and consists of at least two steps: slow nucleation and fast autocatalytic growth. The kinetics of these two processes depends on the reductant "power" and the addition of stabilizers, as well as other factors (e.g., temperature, pH, ionic strength). Knowing these parameters, it is possible to synthesize materials with appropriate physicochemical properties, which can be simply adjusted by the type of the used metal, particle morphology and surface property. This, in turn, affects the possibility of their applications in various areas of life, including medicine, catalysis, engineering, fuel cells, etc. However, in some cases, the standard route, i.e., the chemical reduction of a metal precursor carried out in the batch reactor, is not sufficient due to problems with temperature control, properties of reagents, unstable or dangerous intermediates and products, etc. Therefore, in this review, we focused on an alternative approach to their chemical synthesis provided by microreactor systems. The use of microreactors for the synthesis of noble metal nanomaterials (e.g., Ag, Au, Pt, Pd), obtained by chemical reduction, is analyzed, taking into account investigations carried out in recent years. A particular emphasis is placed on the processes in which the use of microreactors removed the limitations associated with synthesis in a batch reactor. Moreover, the opportunities and challenges related to the synthesis of noble nanomaterials in the microreactor system are underlined. This review discusses the advantages as well as the problems of nanoparticle synthesis in microreactors. [ABSTRACT FROM AUTHOR]

Microreactor technologies have emerged as versatile platforms with the potential to revolutionize chemistry and materials research, offering sustainable solutions to global challenges in environmental and health domains. This survey paper provides an in-depth review of recent advancements in microreactor technologies, focusing on their role in facilitating accelerated discoveries in chemistry and materials. Specifically, we examine the convergence of microfluidics with machine intelligence and automation, enabling the exploitation of the cyber-physical environment as a highly integrated experimentation platform for rapid scientific discovery and process development. We investigate the applicability and limitations of microreactor-enabled discovery accelerators in various chemistry and materials contexts. Despite their tremendous potential, the integration of machine intelligence and automation into microreactor-based experiments presents challenges in establishing fully integrated, automated, and intelligent systems. These challenges can hinder the broader adoption of microreactor technologies within the research community. To address this, we review emerging technologies that can help lower barriers and facilitate the implementation of microreactor-enabled discovery accelerators. Lastly, we provide our perspective on future research directions for democratizing microreactor technologies, with the aim of accelerating scientific discoveries and promoting widespread adoption of these transformative platforms. [ABSTRACT FROM AUTHOR]

Abstract Background Vildagliptin (VLG), an antidiabetic agent, presents a potential solution to this widespread affliction. It exhibits notable attributes, such as a high solubility and a shorter elimination half-life. The current study uses a microreactor to fabricate sustained-release VLG-encapsulated cross-linked chitosan–dextran sulfate nanoparticles (VLG-CDNPs). The fabrication was systematically optimized using the design of experiment approach. Results The optimized VLG-CDNPs had an average particle size of 217.4 ± 12.3 nm and an encapsulation efficiency of 78.25 ± 3.0%. Scanning electron microscopy revealed that the nanoparticles had a smooth spherical shape. Spray drying was used for drying, and the reconstitution ability was close to ideal (~ 1.33). In vitro studies revealed sustained VLG release over 12 h, with ~ 58% in acidic and ~ 83% in basic conditions. Cell viability remained at 80% even at 100 μg/mL, and glucose uptake in L6 cells was significantly enhanced with VLG-CDNPs (78.34%) compared to pure VLG (60.91%). VLG-CDNPs also showed moderate inhibitory activity against α-amylase (41.57%) and α-glucosidase (63.48%) compared to pure VLG, which had higher inhibition levels. Conclusion The study’s outcome suggested that the optimized VLG-CDNPs may serve as an effective and promising nanoformulation for managing diabetes mellitus.

The present study reports a fast and efficient chemical decontamination of water using a tree-branched centimetre-scale microfluidic reactor where zinc oxide nanowires (ZnONWs) act as a photocatalyst. Direct growth of ZnONWs on a silicon wafer with a surface of 1.5 × 1.5 cm2 within the microfluidic chamber brings this photocatalytic medium at the very close vicinity of the water flow path, hence minimising the required interaction time to produce efficient purification performance. The phase and the composition of ZnONWs were characterised by XRD and showing an excellent crystallinity. The microreactor consists of two dendritic microchannels for fluid input/output with a chamber volume 30 μl. The performance of microreactor was evaluated by measuring one-pass ibuprofen (IBP) removal yield. It is shown that the IBP concentration changes over time and increased from 25% to 97% with decreasing the IBP concentration. ZnONWs show excellent photocatalytic IBP degradation efficiency (>99%) under UV light in less than 60 seconds in one pass. Therefore, the high surface/volume ratio would significantly improve the mass transfer efficiency. To describe the kinetics of photocatalytic reaction, the model of Langmuir-Hinshelwood is applied in the form of a pseudo first-order model. [ABSTRACT FROM AUTHOR]

As the nuclear industry develops new advanced reactor technologies, many companies are embracing this advancement by pursuing the development of microreactors. The term microreactor generally refers to a nuclear reactor with an operating power of 20 MW(thermal) or less. The power range of microreactors makes them appealing for many use cases, such as powering remote communities, mining sites, and military bases. Most of the microreactor designs being pursued are expected to incorporate remote facility operations into the final product. However, no framework has yet been developed to determine what remote operations systems require for reliable, resilient, and secure operation of a microreactor. This work identifies the research needs for challenges that are unique to remote operations and monitoring for microreactors, specifically regarding instrumentation and control, communication methods, regulatory requirements, and operational policies. The types of commands and sensor measurements that must be transmitted between the facilities, as well as methods for verifying the trustworthiness of these signals, are assessed. This work evaluates the security, reliability, and performance requirements that must be met when considering the selection of communication hardware and protocols for use in remote operations. Also, an assessment was performed to study how remote operations fit within current regulatory requirements and what may need to be updated in regulatory policy to allow for remote operation. Finally, the operational contingencies unique to remote operations that must be in place for responses to abnormal events are identified. This paper identifies the challenges and research opportunities within the areas of importance for the design of remote operation systems. [ABSTRACT FROM AUTHOR]

Microreactors, a specific class of nuclear reactor, feature a thermal power output of <20 MW, with intended use cases ranging from power production for remote localities and industrial facilities, to military applications, to disaster relief. Because the remote locations of these reactors make repairs difficult, and with continuous power production being essential for the intended use cases, the control system for microreactors should be able to operate or safely shut down the reactor under abnormal conditions (e.g. cases of component failure). The nuclear industry is currently pursuing various microreactor designs, one of which is the heat pipe (HP)–cooled microreactor. A potential failure mechanism in this type of microreactor is individual HP failure. The present work explores the notion that even if a single HP fails, an HP-cooled microreactor may still be controllable in its degraded state. A framework is presented for the stable control of an HP-cooled microreactor system's thermal output power and temperature regulation under both normal and HP failure conditions, using adaptive model predictive control (A-MPC). A-MPC was implemented for its ability to maintain optimal controller performance under changing plant state and system constraints. The complex, nonlinear physical phenomena present in an HP-cooled microreactor make using a physics-based model as the A-MPC controller's internal predictor impractical. Thus, a data-based surrogate predictor model was developed for use under both normal and HP failure conditions. The subject under study is a 37-HP system intended to simulate the HP and core thermal behavior of an HP-cooled microreactor. This system was modeled and simulated in DireWolf, a Multiphysics Object-Oriented Simulation Environment (MOOSE)–based application designed to simulate HP-cooled microreactors. The resulting model was used to generate training data for the data-based predictor model and served as the plant simulator when coupled with the A-MPC controller. This paper presents the data-based predictor model of the 37-HP system, the A-MPC controller architecture that proved suitable under both normal and HP failure microreactor conditions, and the performance of the controller when coupled with the DireWolf simulation of the 37-HP system under both normal and HP failure conditions. [ABSTRACT FROM AUTHOR]

Abstract COVID-19 has caused a worldwide pandemic, creating an urgent need for early detection methods. Breath analysis has shown great potential as a non-invasive and rapid means for COVID-19 detection. The objective of this study is to detect patients infected with SARS-CoV-2 and even the possibility to screen between different SARS-CoV-2 variants by analysis of carbonyl compounds in breath. Carbonyl compounds in exhaled breath are metabolites related to inflammation and oxidative stress induced by diseases. This study included a cohort of COVID-19 positive and negative subjects confirmed by reverse transcription polymerase chain reaction between March and December 2021. Carbonyl compounds in exhaled breath were captured using a microfabricated silicon microreactor and analyzed by ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). A total of 321 subjects were enrolled in this study. Of these, 141 (85 males, 60.3%) (mean ± SD age: 52 ± 15 years) were COVID-19 (55 during the alpha wave and 86 during the delta wave) positive and 180 (90 males, 50%) (mean ± SD age: 45 ± 15 years) were negative. Panels of a total of 34 ketones and aldehydes in all breath samples were identified for detection of COVID-19 positive patients. Logistic regression models indicated high accuracy/sensitivity/specificity for alpha wave (98.4%/96.4%/100%), for delta wave (88.3%/93.0%/84.6%) and for all COVID-19 positive patients (94.7%/90.1%/98.3%). The results indicate that COVID-19 positive patients can be detected by analysis of carbonyl compounds in exhaled breath. The technology for analysis of carbonyl compounds in exhaled breath has great potential for rapid screening and detection of COVID-19 and for other infectious respiratory diseases in future pandemics.

In the present study, a comparison of the dry reforming of a gas mixture containing methane, carbon dioxide and nitrogen without contaminants to a ruthenium-based Ru/Al2O3 catalyst was carried out in a microreactor for the first time. The influence of the contact time, temperature and composition of the feed on the conversion was exhaustively investigated. The optimal operating conditions were found to be a contact time of 80 milliseconds, a temperature of 700 °C and a CH4:CO2 ratio of 1. The assessment of diffusional limitations reveals that there is no resistance to mass transfer, which reveals the potential benefit of the determination of intrinsic reaction kinetics within a microreactor.

AbstractIdaho National Laboratory and the National Reactor Innovation Center (NRIC) constructed the Microreactor Agile Non-nuclear Experimental Test bed (MAGNET) to reduce uncertainty and risk for microreactor developers, users, and regulators. Additional capabilities, dubbed the Helium Component Test Facility (He-CTF) were added after construction was finished to provide a heat exchanger testing capability. The He-CTF construction was funded by the NRIC. MAGNET will generate validation data for dynamic modeling and scaling, thus enabling demonstration and validation of microreactor systems, components, and auxiliary systems. MAGNET was designed primarily for steady-state and normal startup, shutdown, and ramp transients around typical air-Brayton-cycle parameters of 650°C and 22 bar at a differential temperature of 290°C across the reactor. Some accident conditions, such as heat pipe failures, were envisioned. The facility has a capacity of 250 kW and can use nitrogen (N2) or helium (He), with maximum mass flow rates of 938 g/s for N2 and 70 g/s for He. [ABSTRACT FROM AUTHOR]

Photocatalytic overall splitting of pure water (H2O) without sacrificial reagent to hydrogen (H2) and oxygen (O2) holds a great potential for achieving carbon neutrality. Herein, by anchoring cobalt sulfide (Co9S8) as cocatalyst and cadmium sulfide (CdS) as light absorber to channel wall of a porous polymer microreactor (PP12), continuous violent H2 and O2 bubbling productions from photocatalytic overall splitting of pure H2O without sacrificial reagent is achieved, with H2 and O2 production rates as high as 4.41 and 2.20 mmol h−1 gcat.−1 respectively. These are significantly enhanced than those in the widely used stirred tank‐type reactor in which no O2 is produced and H2 production rate is only 0.004 mmol h−1 gcat.−1. Besides improved charge separation and interaction of H2O with photocatalyst in PP12, bonding interaction of Co9S8 with PP12 creates abundant catalytic active sites for simultaneous productions of H2 and O2, thus leading to the significantly enhanced H2 and O2 bubbling productions in PP12. This offers a new strategy to enhance photocatalytic overall splitting of pure H2O without sacrificial reagent. [ABSTRACT FROM AUTHOR]

AbstractMicroreactors are expected to be deployed in locations or situations where standard macrogrid electricity is not readily or reliably available. Locations such as remote mining communities, military installations, and other similar communities may seek to decarbonize their electricity with a microreactor. Traditional remote communities typically pay much higher energy prices than nonremote communities, so there may be a higher degree of support for microreactors despite higher expected (per unit capacity) capital costs. There is also interest in deploying microreactors on sites that utilize their own microgrids, for example, federal installations or universities, in different locations across the United States. To model the deployment prospects of microreactors on microgrids, HOMER Pro was utilized to generate optimized microgrid configurations under an assumption of net zero, i.e. with no fossil fuels permitted. The economic performance of microreactors on microgrids was analyzed in a variety of locations throughout the United States. It was found that the minimal capital cost required for entry of a microreactor into the system was significantly higher in locations with both low solar resource (less than ~4.5kW∙h/m2∙day−1) and (in particular) low wind (<5 m/s average wind velocity at 80-m hub height), roughly corresponding to locations somewhat inland in both the eastern and the western United States. Under the financial assumptions made in this study, depending on location, the capital cost at which microreactors could enter the system varied from around $24 000/kW(electric) in areas of high wind and/or solar resource to over $90 000/kW(electric) in Alaska, with a range of intermediate results. It was found that the minimum allowed power level of the microreactor did not have a substantial impact on results. A utility presence was found to have a major impact on the financial performance of a microreactor, especially in locations that have strong renewable resources. [ABSTRACT FROM AUTHOR]

AbstractResearchers who are actively developing nuclear microreactors are planning to employ innovative designs and features using traditional commercial modeling tools that may be inadequate for their design and licensing activities. The codes developed under the U.S. Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) program provide flexibility in terms of geometry modeling and multiphysics coupling and are particularly well suited for modeling novel microreactor concepts. To test the maturity of these codes, this paper introduces a conceptual heat pipe microreactor (HP-MR) designed to gather various technologies of interest to microreactor developers such as control drums, heat pipes, and hydride moderators. The objective of this effort is to demonstrate NEAMS tools capability to perform high-fidelity multiphysics simulations, using coupled neutronics (via the Griffin code), heat conduction (via the BISON code), heat pipe modeling (via the Sockeye code), and hydrogen redistribution in hydride metal moderator (via the SWIFT code). Codes are coupled in-memory through the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework, which permits flexible multiphysics data transfer schemes. The analysis confirmed two key aspects of the HP-MR concept: (1) its ability to follow the power load requested from the heat pipe and (2) its ability to avoid heat pipe cascading failure unless designed with high power close to operating failure limits of its heat pipes. The developed computational model was distributed publicly on the Virtual Test Bed for training purposes to accelerate adoption by industry and to provide a high-fidelity multiphysics solution for benchmarking against other tools. Additional multiphysics analyses including other transients and coupled physics were identified as necessary future work, together with a focus on validating multiphysics behavior against experiments. [ABSTRACT FROM AUTHOR]

Metal‐Organic Frameworks (MOFs) represent a highly promising class of materials with diverse applications, particularly as catalytic materials. However, their synthesis typically yields powders available only at laboratory‐scale quantities, usually in the gram range or less. This study addresses the challenge of testing limited amounts of MOF catalysts for demanding applications, such as multiphase gas‐liquid‐solid reactions in flow, utilizing a packed‐bed microreactor. Specifically, we investigate the performance of a nanoparticle (NP) ‐immobilized Pd@UiO‐66 MOF catalyst in the selective semi‐hydrogenation of phenylacetylene to styrene, serving as a model reaction. Maintaining the Taylor flow regime upstream of the catalyst bed was crucial to ensure reproducible and reliable experimental results. We conducted 88 experiments at varying liquid flow rates, temperatures ranging from 15 to 45 °C, and relative pressures spanning 0.28 to 8 bar. Styrene selectivity within the range of 80–92.3 % was achieved at phenylacetylene conversions below 20 %. Notably, the optimal condition for styrene selectivity (70 %) was attained at 98.9 % phenylacetylene conversion under the lowest H2 pressure and highest temperature, demonstrating the significance of low H2 concentration for achieving optimal styrene selectivity. Remarkably, the catalyst exhibited stable activity and selectivity over a 20 h testing period, indicating its robust performance under prolonged reaction conditions. This study demonstrates the potential of the proposed catalyst testing system as a rapid and efficient approach for early‐stage exploration studies, particularly when limited quantities of catalyst, typically in the gram scale or less, are available. [ABSTRACT FROM AUTHOR]

The mechanics of capillary force in biological systems have critical roles in the formation of the intra- and inter-cellular structures, which may mediate the organization, morphogenesis, and homeostasis of biomolecular condensates. Current techniques may not allow direct and precise measurements of the capillary forces at the intra- and inter-cellular scales. By preserving liquid droplets at the liquid-liquid interface, we have discovered and studied ideal models, i.e., interfacial liquids and marbles, for understanding general capillary mechanics that existed in liquid-in-liquid systems, e.g., biomolecular condensates. The unexpectedly long coalescence time of the interfacial liquids revealed that the Stokes equation does not hold as the radius of the liquid bridge approaches zero, evidencing the existence of a third inertially limited viscous regime. Moreover, liquid transport from a liquid droplet to a liquid reservoir can be prohibited by coating the droplet surface with hydrophobic or amphiphilic particles, forming interfacial liquid marbles. Unique characteristics, including high stability, transparency, gas permeability, and self-assembly, are observed for the interfacial liquid marbles. Phase transition and separation induced by the formation of nanostructured materials can be directly observed within the interfacial liquid marbles without the need for surfactants and agitation, making them useful tools to research the interfacial mechanics. [ABSTRACT FROM AUTHOR]

AbstractAn analysis of the stability margins of the innovative Holos-Quad microreactor design is presented. This high-temeprature gas-cooled reactor (HTGR) system is designed to operate fully autonomously with passive safety mechanisms. Therefore, the inherent stability of the reactor is of great importance. Using a point-reactor model, which couples point kinetics to thermal-hydraulic heat balance equations and includes reactivity feedback effects of the fuel and moderator temperatures, the closed-loop transfer function of the reactor is derived. Applying the approach of linear systems and control theory, both the gain and phase margins of the Holos-Quad design are obtained. The analysis demonstrates that the design is stable, with an infinite gain margin and a finite phase margin.A parametric uncertainty quantification study is also performed using a total Monte Carlo approach. The stability of the reactor for different power levels, such as during reactor startup or load-following transients, is also explored. Finally, two sensitivity analysis methods are applied, namely, multiple regression (deriving standardized regression coefficients) and variance-based sensitivity analysis (known as the Sobol method), to study the contribution of each of the parameters to the stability margins’ uncertainty. This analysis improves our understanding of the role of each of the parameters in the stability of the reactor. [ABSTRACT FROM AUTHOR]

The flash organometallic catalysis is a new concept that refers to the study of fast and controlled organometallic catalytic reactions by using microfluidic devices. Flash reactions' kinetics (ms‐s scale) is often ignored due to the lack of proper research tool in organometallic chemistry. The development of microfluidic systems offers the opportunity to discover under‐studied mechanisms and new reactions. In this concept, the basic theory of kinetic measurement in a microreactor is briefly reviewed and then two examples on studying flash organometallic catalytic transformation are introduced. One example is the discovery of a highly active palladium catalytic species for Suzuki Coupling and the other example is the study of a neglected isomerization catalytic cycle with a time scale of seconds before isomerization‐hydroformylation by customized microfluidic devices. The last part is summary and prospect of this new area. Customizing a microfluidic device with good engineering design for a target reaction supports flash reactions' kinetic experimentation and could become a general strategy in chemistry lab. [ABSTRACT FROM AUTHOR]

Accurate control of core–shell lipopolyplex nanoparticles (LPP NPs) size is crucial for finely adjusting their biomedical performance. However, the synthesis of LPP NPs encounters challenges as two mixing-sensitive processes are involved in the synthesis, rendering precise control over particle size difficult using conventional batch methods. In this study, the formation of the nucleic acid/cationic polymer cores through electrostatic complexation and the subsequent encapsulation by lipid shells via self-assembly were conducted in microreactors, with polyadenylic acid (poly A) and branched polyethylenimine (bPEI) employed as the model system. By assessing the micromixing performance of the microreactors using the Villermaux-Dushman method, the characteristic time scale for electrostatic complexation between poly A and bPEI, as well as the self-assembly of lipids, was determined to be below 1 ms. The Reynolds number, governing micromixing performance, emerged as a crucial factor influencing the sizes of poly A/bPEI cores and LPP NPs. In the kinetic control region, characterized by rapid mixing, the size of poly A/bPEI remained slightly influenced by the N/P molar ratio and volumetric flow rate ratio, irrespective of concentration. The zeta potential, however, was primarily affected by the N/P molar ratio. In the case of LPP NPs, under optimized conditions of anionic lipid molar ratio, the size of LPP NPs was significantly influenced by the composition of lipid shells. This study establishes the foundation for elucidating the structure–activity relationship of LPP NPs. [ABSTRACT FROM AUTHOR]

Azo compounds find use in many areas of science, displaying crucial properties for important applications as photoconductive organic pigments, fluorescent quenchers, paints, cosmetics, inks, and in the large and valuable dye industry. Due to the unstable intermediates, and the exothermic and fast reactions used in their synthesis, high value azo compounds are excellent candidates for continuous flow manufacturing. This comprehensive review covers the progress made to date on developing continuous flow systems for azo synthesis and reflects on the main challenges still to be addressed, including scale up, conversion, product purity, and environmental impact. The further development of integrated continuous flow processes has the potential to help tackle these challenges and deliver improved methods for azo compound generation. [ABSTRACT FROM AUTHOR]

The potential deployment of microreactors as a zero-emission source for critical applications within integrated energy systems such as microgrids has been gaining interest in recent years owing to the microreactors' dispatchable nature, modular design, small site footprint, and carbon-free generation. A particularly high-value but challenging application with rapidly growing demand is in the deployment of high-performance computing (HPC) clusters within microgrids. In this work, a model of a HPC cluster in an energy-diverse microgrid is developed to determine the requirements of a technology-agnostic microreactor deployed for such a challenging application. The minute-resolution simulations revealed that the cluster's electrical load fluctuation of up to 4.1 MW/min required a fast and responsive load-following capability. When the load-following capability of the microreactor was perturbed, the required microgrid storage capacity associated with having a 0.1 MW/min dispatchable microreactor decreased by two orders of magnitude as compared with load-following solely by energy storage devices, indicating that load-following capability in microreactors is of great value in such applications. The analysis methods described in this work can be extended to other microgrids, other HPC clusters, or other types of challenging applications, and can help microgrid planners in determining the storage size, output capacity, and ramping capabilities of the storage devices required for a given microgrid configuration. [ABSTRACT FROM AUTHOR]

Microreactors comprise a new actively developing class of very small advanced reactors that have the potential to be an alternative to carbon-intensive energy technologies. A microreactor based on high-temperature gas reactor (HTGR) technology is a very promising advanced reactor with inherent safety, and it can couple with a closed Brayton cycle for higher efficiency. Since dynamics characteristics are fundamental to analyzing a power generation system and a reactor is the main source of the dynamics characteristics of a system, it is necessary to study a microreactor model suitable for system analysis. The main goal is to simulate the performance of the previously mentioned integrated system, focusing on the details of the power conversion unit while still ensuring acceptable calculation times. Hence, a simplified reactor model is needed that could supply sufficiently accurate values of pressure drop and heat transfer across the core. In this paper, by simplifying the physical processes in a microreactor, a dynamic model described by differential algebraic equations is obtained based on the lumped parameter modeling methodology and the basic conservation of fluid mass, momentum, and energy. Coupling thermal hydraulics with neutron kinetics, the temperature coefficient of reactivity and xenon poisoning are considered. Finally, the model is programmed and calculated using Modelica language. The transient responses of the main parameters under typical perturbations are analyzed, and the results show that the responses are correct. Because of the effect of reactivity feedback, fluctuations of the main parameters caused by microperturbations eventually tend to stabilize. In addition, the effects of negative reactivity introduced by xenon poisoning under two typical dynamic processes are analyzed. In power regulation, excess reactivity is required to compensate for the negative reactivity introduced by 135Xe. The model and results can properly predict the systematic parameters and serve as a basis for system analysis of microreactor coupling with the helium closed Brayton cycle. [ABSTRACT FROM AUTHOR]

[Display omitted] The key feature of living cells is multicompartmentalization for enzymatic reactions. Artificial cell-like multicompartments with micro domains are appealing to mimic the biological counterparts. In addition, establishing a sustainable, efficient, and controllable reaction system for enzymatic hydrolysis is imperative for the production of natural fatty acids from animal and plant-based fats. Reverse Janus emulsion microreactors, i.e. (W 1 + W 2)/O, is constructed through directly using natural fats as continuous phase and aqueous two-phase solutions (ATPS) as inner phases. Enzyme is confined in the compartmented aqueous droplets dominated by the salt of Na 2 SO 4 and polyethylene glycol (PEG). Enzyme catalyzed ester hydrolysis employed as a model reaction is performed under the conditions of agitation-free and mild temperature. Regulation of reaction kinetics is investigated by diverse droplet topology, composition of inner ATPS, and on-demand emulsification. Excellent enzymatic activity toward hydrolysis of plant and animal oils achieves 88.5 % conversion after 3 h. Compartmented micro domains contribute to condense and organize the enzymes spatially. Timely removal of the products away from reaction sites of oil/water interface "pushed" the reaction forward. Distribution and transfer of enzyme in two aqueous lobes provide extra freedom in the regulation of hydrolysis kinetics, with equilibrium conversion controlled freely from 14.5 % to 88.5 %. Reversible "open" and "shut" of hydrolysis is acheived by on-demand emulsification and spontaneous demulsification. This paper paves the way to advancing progress in compartmentalized emulsion as a sustainable and high-efficiency platform for biocatalytic applications. [ABSTRACT FROM AUTHOR]

In recent years, with the outbreak of the global energy crisis, renewable solar energy has become a focal point of research. However, the utilization efficiency of natural photosynthesis (NPS) is only about 1%. Inspired by NPS, artificial photosynthesis (APS) was developed and utilized in applications such as the regeneration of coenzymes. APS for coenzyme regeneration can overcome the problem of high energy consumption in comparison to electrocatalytic methods. Microreactors represent a promising technology. Compared with the conventional system, it has the advantages of a large specific surface area, the fast diffusion of small molecules, and high efficiency. Introducing microreactors can lead to more efficient, economical, and environmentally friendly coenzyme regeneration in artificial photosynthesis. This review begins with a brief introduction of APS and microreactors, and then summarizes research on traditional electrocatalytic coenzyme regeneration, as well as photocatalytic and photo-electrocatalysis coenzyme regeneration by APS, all based on microreactors, and compares them with the corresponding conventional system. Finally, it looks forward to the promising prospects of this technology. [ABSTRACT FROM AUTHOR]

In the present study, a comparison of the dry reforming of a gas mixture containing methane, carbon dioxide and nitrogen without contaminants to a ruthenium-based Ru/Al2O3 catalyst was carried out in a microreactor for the first time. The influence of the contact time, temperature and composition of the feed on the conversion was exhaustively investigated. The optimal operating conditions were found to be a contact time of 80 milliseconds, a temperature of 700 °C and a CH4:CO2 ratio of 1. The assessment of diffusional limitations reveals that there is no resistance to mass transfer, which reveals the potential benefit of the determination of intrinsic reaction kinetics within a microreactor. [ABSTRACT FROM AUTHOR]

Recently, a smart strategy for two-dimensional (2D) materials synthesis has emerged, namely space-confined chemical vapor deposition (CVD). Its extreme case is the microreactor method, in which the growth substrate is face-to-face stacked on the source substrate. In order to grow 2D transition metal dichalcogenides by this method, transition metal oxides, dispersed in very small amounts on the source substrate, are used as source materials in most of the published reports. In this paper, a colloidal dispersion of MoS2 in saline solution is used and MoS2 nanosheets with various shapes, sizes (between 5 and 60 μm) and thicknesses (2–4 layers) have been synthesized. Small MoS2 flakes (regular or defective) are present on the surface of the nanosheets. Catalytic sites, undercoordinated atoms located at the edges of MoS2 flakes and nanosheets, are produced in a high number by a layer-plus-island (Stranski–Krastanov) growth mechanism. Several double-resonance Raman bands (at 147, 177, 187, 225, 247, 375 cm−1) are assignable to single phonon processes in which the excited electron is elastically scattered on a defect. The narrow 247 cm−1 peak is identified as a topological defect-activated peak. These findings highlight the potential of defect engineering in material property optimization, particularly for solar water splitting applications. [ABSTRACT FROM AUTHOR]

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The oxidation of cyclohexanol/cyclohexanone with nitric acid as a fast and highly exothermic process was hard to control at low molar ratios of oxidant to organic substrate even in microreactors. Process of runaway gas generation was observed due to the local hot spots, which decreased the selectivity of adipic acid. Additional gas was introduced into microreactors before the reaction, changing the previous wave annular flow to the uniform slug flow. Through the microscopic high‐speed photography and CFD simulation, it was found that the internal convection made the reactant molecules in the aqueous slug distribute evenly instead of gathering near the interface before, thus eliminating the local hot spots and stabilizing the hydrodynamic characteristics. The reaction performance was evaluated under different conditions, and a higher adipic acid selectivity of 93.6% was achieved at a molar ratio of 6.7 with the combination of microreactors and conventional reactors. [ABSTRACT FROM AUTHOR]

The growing discovery and development of novel radiopharmaceuticals and radiolabeling methods requires an increasing capacity for radiochemistry experiments. However, such studies typically rely on radiosynthesizers designed for clinical batch production rather than research, greatly limiting throughput. Two general solutions are being pursued to address this: developing new synthesis optimization algorithms to minimize how many experiments are needed, and developing apparatus with enhanced experiment throughput. We describe here a novel high-throughput system based on performing arrays of droplet-based reactions at 10 μL volume scale in parallel. The automatic robotic platform can perform a set of 64 experiments in ~3 h (from isotope loading to crude product, plus sampling onto TLC plates), plus ~1 h for off-line radio-TLC analysis and radioactivity measurements, rather than the weeks or months that would be needed using a conventional system. We show the high repeatability and low crosstalk of the platform and demonstrate optimization studies for two 18F-labeled tracers. This novel automated platform greatly increases the practicality of performing arrays of droplet reactions by eliminating human error, vastly reducing tedium and fatigue, minimizing radiation exposure, and freeing up radiochemist time for other intellectually valuable pursuits.

Exploring the potential of microfluidic systems, this study presents a groundbreaking approach harnessing energy in microfluidic flows within a purpose‐built microreactor, enabling precise deposition of functional biomaterials. Upon optimizing reactor dimensions and integrating it into a microfluidic system, sequentially flow‐induced deposition of DNA hydrogels and transformation into DNA‐protein hybrid materials with SpyTag/SpyCatcher technology is investigated. However, limited functionalization rates restrict its viability for targeted biocatalytic processes. Therefore, the direct deposition of a phenolic acid decarboxylase is investigated, which is efficiently deposited but shows limited biocatalytic performance due to shear‐induced denaturation. This challenge is overcome by a two‐step immobilization process, resulting in microfluidic bioreactors demonstrating initial high space‐time yields of up to 7000 g L−1 d−1, but whose process stability proves unsatisfactory. However, by exploiting the principle of flow‐induced deposition to immobilize recombinant E. coli cells as functional living materials overexpressing biocatalytically relevant enzymes, bioreactors are produced that show equally high space‐time yields in continuous whole‐cell catalysis which remain constant over periods of up to 10 days. The insights gained offer optimization strategies for advanced functional materials and innovative reactor systems holding promise for applications in fundamental materials science, biosensing, and scalable production of microreactors for biocatalysis and bioremediation. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) with a long-lifetime room-temperature phosphorescence (RTP) have received considerable attention but still remain a great challenge, especially for synthesizing visible-light-excited RTP CDs. Until now, most studies have applied isolated and chromophorous reactants to achieve visible-light-excited RTP CDs. Therefore, those strategies to modulate the excitation wavelength are not referential or reproducible. Herein, surface amination and combination with boric acid (BA, H3BO3) of CDs are applied to build long-lifetime RTP, which drives excitation light from the ultraviolet (UV) area to the visible area and gives out excitation-related afterglow. Meanwhile, surface amination promotes the intersystem crossing process, increasing the quantum yield to 18.63%. After removal of excitation light, the afterglow time visible to naked eyes can reach 10 s, with a phosphorescence lifetime of 453 ms. Furthermore, time-dependent density functional theory (TDDFT) explained the differentiated influence of surface amination on the triplet state and singlet state, which benefits the idea of realizing a wider region for excitation. Based on the above features, CDs@BA are applied in encryption with different excitation wavelengths in the advanced anticounterfeiting security field. [ABSTRACT FROM AUTHOR]

Despite significant progress in microreactor research, limited throughput hinders their industrial application. The impinging flow method offers a novel approach to scaling up microreactors. In this study, a T-shaped impinging flow reactor was used to investigate the improvement of the throughput of micro-scale devices for the enhanced extraction and separation of zinc from cadmium and manganese using the impinging flow method. Computational fluid dynamics (CFD) simulations were performed to analyze the velocity fields and concentration distributions and gain a better understanding of the mixing and mass transfer phenomena. A comparison of experimental and simulation results under the same conditions was then carried out. Results revealed that decreasing mass transfer efficiency with increased inner diameter, though higher inlet flow rates partially offset this, however beyond a certain threshold, larger channel sizes significantly decrease efficiency. The study also demonstrated that impinging flow reactors exhibit superior volumetric mass transfer coefficients compared to segmented flow microreactors. By increasing the volumetric flow rate and channel inner diameter simultaneously, the millimeter impinging flow reactor achieved the same extraction efficiency as the micrometer segmented flow reactor with a scale-up factor of 1312.5, which indicates a significant increase in device capacity. Overall, this study demonstrates the potential for significant scale-up in device capacity using impinging flow reactors. [ABSTRACT FROM AUTHOR]

The flow characteristics of void fraction and specific surface area are important to predict the mass transfer and reaction performances in gas–liquid microreactors. However, the models and trends for the two parameters in different flow patterns remain ununified and insufficient. Accordingly, this work first time studies the void fraction and specific surface area in a very wide flow pattern range (Taylor, short bubble, bubbly, and bubble swarm flow). The results show that at the same gas–liquid flow rates, the void fraction decreases with bubble size in Taylor and short bubble flow but is totally opposite in bubbly and bubble swarm flow. Importantly, the variation of specific surface area with bubble size is independent of the flow pattern and decreases with bubble size. Finally, based on bubble size, two general models for the two parameters are developed. This work provides a new direction for the unification of flow characteristics. [ABSTRACT FROM AUTHOR]

Nowadays ε-caprolactone, the monomer of biodegradable polycaprolactone, is mainly produced via the strong exothermic Baeyer–Villiger oxidation of cyclohexanone in semi-batch reactors. In this work, the continuous synthesis of ε-caprolactone was conducted in a self-designed microreactor system to address its strong exothermic feature, resulting in a cyclohexanone conversion of 90.3% and an ε-caprolactone yield of 82.6%. Analysis using a liquid chromatography equipped with high resolution time-of-flight mass spectrometer suggested that the byproducts mainly consist of ε-caprolactone oligomers in the form of dimer, trimer, and tetramer. Such oligomers were produced via hydrolysis of ε-caprolactone, followed by esterification of the hydrolysis product, 6-hydroxyhexanoic acid. Kinetic studies suggest that the hydrolysis reaction orders for ε-caprolactone and water are 0.75 and 2.52, respectively, while dimerization of 6-hydroxyhexanoic acid is a zero-order reaction. The activation energies of the hydrolysis and dimerization were ~ 77.5 kJ·mol−1 and ~ 55.4 kJ·mol−1, respectively. Density functional theory calculations revealed the significant catalytic effect of acetic acid on both side reactions, where the dimerization of 6-hydroxyhexanoic acid proceeds through an alkoxy pathway. Highlights: • Continuous synthesis of ε-caprolactone was conducted in a microreactor to address its strong exothermic feature • Side reactions consist of hydrolysis of ε-caprolactone and oligomerization of 6-hydroxyhexanoic acid • Kinetic parameters were obtained and an alkoxy pathway was proposed for the dimerization of 6-hydroxyhexanoic acid [ABSTRACT FROM AUTHOR]

The recent advances in the area of electrophotocatalysis (EPC) show that it is a highly suitable technique to yield greener and more sustainable organic synthesis. The overall productivity of EPC however is constrained by a multitude of practical limitations, which impose difficulties in effectively harmonizing the photochemical and electrochemical steps, let alone in accelerating both steps simultaneously. In this contribution, we have tackled these limitations by developing a parallel plate flow cell that permits the execution of EPC in continuous flow. By using a transparent electrode, such as fluorine-doped tin oxide (FTO) or indium tin oxide (ITO) coated glass, the interelectrode distance could be reduced while improving photon absorption. By enhancing both the photochemical and electrochemical steps simultaneously, a notable increase in productivity and space–time-yield (a ten-fold and 300-fold improvement, respectively) of the N-arylation of different azoles was observed. In addition, this was achieved in a single-pass process under electrolyte-free conditions. Highlights: • We have created a flow cell that incorporates a transparent electrode, allowing simultaneous photochemical and electrochemical activation. • By using a parallel energy input, a productivity increase for the N-arylation of different azoles under electrolyte-free conditions was observed. • A single pass sufficed to reach high conversions, rendering this a true continuous flow process. [ABSTRACT FROM AUTHOR]

This investigation used a tubular microreactor to produce Vildagliptin (VLG) loaded ethyl cellulose (EC) nanoparticles (NPs) for sustained delivery of a drug. A central composite design was used to quantify the influence of independent variables on the desired responses. The independent factors selected to achieve the desired entrapment efficiency and sustained drug release were EC concentration and sodium lauryl sulfate concentration. On the other hand, the dependent variables chosen for assessment were particle size (Y1) and encapsulation efficiency (Y2). The nanoparticles produced were analyzed, which included particle size measurement, transmission electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, encapsulation efficiency (EE) determination, and in vitro drug release study. The optimized samples TEM investigation verified the nanoparticles' spherical shape and particle size distribution, ranging from 160 to 250 nm. The entrapment efficiency (EE) fell within the range of 63–87%. In the in-vitro drug release study, VLG-loaded EC nanoparticles exhibited sustained release over 12 h. Applying various kinetic equations to the in-vitro drug release data demonstrated that the drug release mechanism involved diffusion. This comprehensive study concluded that the VLG-EC-NPs achieved optimal particle size, EE, and desirable level of sustained drug release. [ABSTRACT FROM AUTHOR]