Small-scale Reaction Research Articles

Methodologies for alternative jet fuels testing on small-scale reaction engines

Methodologies for alternative jet fuels testing on small-scale reaction engines

Expanding the toolbox for microfluidic-based in situ membrane characterization via microscopy

Polyamide thin film composite membranes are the commercial standard for aqueous nanofiltration and reverse osmosis. Establishing their synthesis-structure-performance relationships (SSPs), needed for rational membrane design, is hampered by the small scale and high reaction rate of interfacial polymerization (IP). Microfluidic devices, compatible with microscopic real-time visualization of IP and performance testing of the formed film, are interesting within this respect. In this study, a new microfluidic design and operational protocol for in situ characterization of IP is developed. Difficulties encountered with microfluidics and coping strategies are highlighted. The outcome of the optimization study proves that a parylene-coated PDMS-glass chip comprising a channel lay-out with 4 inlets, 2 outlets, a channel height of 20 μm, and a reaction channel length ≤50 μm is most compatible with IP and performance testing. Varying synthesis conditions show changing film morphology and water flux in line with trends for dip-coated membranes. Addition of NaHCO3 and ethyl acetate induce morphological features and increase water flux. Increasing TMC concentrations decrease water flux until an excess is generated. By combining the developed protocol and microfluidic device with an online measurement technique to probe film formation dynamics, such as fluorescence microscopy, SSPs can be derived in the future.

Long-Term Hydrogen Production from a Methanol–Water Solution Catalyzed by an Iridium Complex

Long-term hydrogen production from a methanol–water solution was achieved by developing a new reaction system employing a homogeneous iridium catalyst bearing a bipyridonate-type functional ligand. By optimizing the methanol:water ratio of the reaction solution, the efficiency of hydrogen production was greatly improved in relation to that reported in our previous studies. Additionally, the effect of the scale of reaction was investigated. It was found that a small-scale reaction led to a longer lifetime of the iridium catalyst, accomplishing long-term continuous hydrogen production at a constant rate for over 500 h. Furthermore, procedures for catalyst reuse were studied. After hydrogen production for 400 h, all volatiles in the reaction system were removed under vacuum. This simple procedure is highly effective for the reactivation and reuse of the catalyst. Finally, hydrogen production (13.7 L, 562 mmol) from methanol (12.3 mL, 303 mmol) and water (5.46 mL, 303 mmol), in a continuous reaction for 800 h, was achieved.

Four thermostatic steps: A novel CRISPR-Cas12-based system for the rapid at-home detection of respiratory pathogens.

The outbreak of coronavirus disease 2019 (COVID-19) in 2019 has severely damaged the world's economy and public health and made people pay more attention to respiratory infectious diseases. However, traditional quantitative real-time polymerase chain reaction (qRT-PCR) nucleic acid detection kits require RNA extraction, reverse transcription, and amplification, as well as the support of large-scale equipment to enrich and purify nucleic acids and precise temperature control. Therefore, novel, fast, convenient, sensitive and specific detection methods are urgently being developed and moving to proof of concept test. In this study, we developed a new nucleic acid detection system, referred to as 4 Thermostatic steps (4TS), which innovatively allows all the detection processes to be completed in a constant temperature device, which performs extraction, amplification, cutting of targets, and detection within 40min. The assay can specifically and sensitively detect five respiratory pathogens, namely SARS-CoV-2, Mycoplasma felis (MF), Chlamydia felis (CF), Feline calicivirus (FCV), and Feline herpes virus (FHV). In addition, a cost-effective and practical small-scale reaction device was designed and developed to maintain stable reaction conditions. The results of the detection of the five viruses show that the sensitivity of the system is greater than 94%, and specificity is 100%. The 4TS system does not require complex equipment, which makes it convenient and fast to operate, and allows immediate testing for suspected infectious agents at home or in small clinics. Therefore, the assay system has diagnostic value and significant potential for further reducing the cost of early screening of infectious diseases and expanding its application. KEY POINTS: • The 4TS system enables the accurate and specific detection of nucleic acid of pathogens at 37°C in four simple steps, and the whole process only takes 40min. •A simple alkali solution can be used to extract nucleic acid. • A small portable device simple to operate is developed for home diagnosis and detection of respiratory pathogens.

Kinetic studies and CFD-based reaction modeling for insights into the scalability of ADC conjugation reactions.

The manufacturing of antibody-drug conjugates (ADCs) involves the addition of a cytotoxic small-molecule linker-drug (= payload) to a solution of functionalized antibodies. For the development of robust conjugation processes, initially small-scale reaction tubes are used which requires a lot of manual handling. Scale-up to larger reaction vessels is often knowledge-driven and scale-comparability is solely assessed based on final product quality which does not account for the dynamics of the reaction. In addition, information about the influence of process parameters, such as stirrer speed, temperature, or payload addition rates, is limited due to high material costs. Given these limitations, there is a need for a modeling-based approach to investigate conjugation scale-up. In this work, both experimental kinetic studies and computational fluid dynamics (CFD) conjugation simulations were performed to understand the influence of scale and mixing parameters. In the experimental part, conjugation kinetics in small-scale reaction tubes with different mixing types were investigated for two ADC systems and compared to larger bench-scale reactions. It was demonstrated that more robust kinetics can be achieved through internal stirrer mixing instead of external mixing devices, such as orbital shakers. In the simulation part, 3D-reactor models were created by coupling CFD-models for three large-scale reaction vessels with a kinetic model for a site-specific conjugation reaction. This enabled to study the kinetics in different vessels, as well as the effect of process parameter variations in silico. Overall, it was found that for this conjugation type sufficient mixing can be achieved at all scales and the studied parameters cause only deviations during the payload addition period. An additional time-scale analysis demonstrated to aid the assessment of mixing effects during ADC process scale-up when mixing times and kinetic rates are known. In summary, this work highlights the benefit of kinetic models for enhanced conjugation process understanding without the need for large-scale experiments.

One-Step Regio- and Stereoselective Electrochemical Synthesis of Orexin Receptor Antagonist Oxidative Metabolites.

Synthesis of drug metabolites, which often have complex structures, is an integral step in the evaluation of drug candidate metabolism, pharmacokinetic (PK) properties, and safety profiles. Frequently, such synthetic endeavors entail arduous, multiple-step de novo synthetic routes. Herein, we present the one-step Shono-type electrochemical synthesis of milligrams of chiral α-hydroxyl amide metabolites of two orexin receptor antagonists, MK-8133 and MK-6096, as revealed by a small-scale (pico- to nano-mole level) reaction screening using a lab-built online electrochemistry (EC)/mass spectrometry (MS) (EC/MS) platform. The electrochemical oxidation of MK-8133 and MK-6096 was conducted in aqueous media and found to produce the corresponding α-piperidinols with exclusive regio- and stereoselectivity, as confirmed by high-resolution nuclear magnetic resonance (NMR) characterization of products. Based on density functional theory (DFT) calculations, the exceptional regio- and stereoselectivity for this electrochemical oxidation are governed by more favorable energetics of the transition state, leading to the preferred secondary carbon radical α to the amide group and subsequent steric hindrance associated with the U-shaped conformation of the cation derived from the secondary α-carbon radical, respectively.

Self-Supervised Molecular Pretraining Strategy for Low-Resource Reaction Prediction Scenarios.

In the face of low-resource reaction training samples, we construct a chemical platform for addressing small-scale reaction prediction problems. Using a self-supervised pretraining strategy called MAsked Sequence to Sequence (MASS), the Transformer model can absorb the chemical information of about 1 billion molecules and then fine-tune on a small-scale reaction prediction. To further strengthen the predictive performance of our model, we combine MASS with the reaction transfer learning strategy. Here, we show that the average improved accuracies of the Transformer model can reach 14.07, 24.26, 40.31, and 57.69% in predicting the Baeyer-Villiger, Heck, C-C bond formation, and functional group interconversion reaction data sets, respectively, marking an important step to low-resource reaction prediction.

Large volume and oxygen tolerant photoinduced aqueous atom transfer radical polymerization

We scaled up the aqueous photoinduced ICAR (PICAR) ATRP of acrylamide (AAm), with a scale-up factor of 400, from Vi = 5.0 mL to Vf = 2.0 L. Relatively large mixtures can be polymerized by 395 nm light, up to very high conversions while maintaining a narrow molecular weight distributions, in the presence of sodium pyruvate, which acts as both reactive oxygen species scavenger and exciter for [CuIL]+ (re)generation. The best reactions conditions were determined by analyzing the buffer strength, halide source nature and concentration, light wavelength, catalyst concentration, sodium pyruvate concentration, and initiator type. PICAR ATRP was successfully applied as well to other hydrophilic monomers besides AAm. The reaction progress could be monitored online via electrochemical methods. The best small-scale reaction was then scaled up with AAm to 40, 250, 500, 1000 and 2000 mL. The estimated crude cost of polyacrylamide (PAAm) and the reagent cost of the reaction mixture revealed that PICAR ATRP is feasible at large scale.

Testing enabling techniques for olefin metathesis reactions of lipophilic substrates in water as a diluent

SummaryOlefin metathesis reactions of diverse polyfunctional substrates were conducted in water emulsions using two hydrophobic ruthenium catalysts in the presence of air. Instead of using surfactants to increase the efficiency of the metathesis reaction in water, ultrasound and microwave techniques were tested on a small-scale reaction, whereas conventional heating and mechanical stirring were effective enough to provide high conversion and selectivity on a larger scale. The developed conditions extend known protocols for the aqueous metathesis methodology, utilizing relatively low catalyst loadings and allowing for simple product isolation and purification. The established synthetic protocol was successfully adopted in the large-scale synthesis of a pharmaceutically related product – sildenafil (Viagra) derivative.

Accelerated Asymmetric Reaction Screening with Optical Assays

AbstractAsymmetric reaction development often involves optimization of several mutually dependent parameters that affect the product yield and enantiomeric excess. Widely available high-throughput experimentation equipment and optical sensing assays can drastically streamline comprehensive optimization efforts and speed up the discovery process at reduced cost, workload, and waste production. A variety of chiroptical assays that utilize fluorescence, UV, and circular dichroism measurements to determine reaction yields and ee values are now available, enabling the screening of numerous small-scale reaction samples in parallel with multi-well plate technology. Many of these optical methods considerably shorten work-up protocols typically required for traditional asymmetric reaction analysis and some can be directly applied to crude mixtures thus eliminating cumbersome separation and purification steps altogether.1 Introduction2 Fluorescence Assays3 UV Sensing Methods4 Sensing with Circular Dichroism Probes5 Hybrid Approaches6 Optical Analysis with Intrinsically CD-Active Reaction Products7 Conclusion

Quick approach for optimization of monodisperse microsphere synthesis with a knowledge sharing strategy powered by machine learning

In this communication, we proposed Bayesian optimization acceleration strategy by allowing machine-learned knowledge to flow across different reaction scales. Dispersion polymerization was conducted to validate this knowledge sharing approach. By learning a product uniformity landscape and performing virtual optimization using high-throughput small-scale reaction data, the most promising recipe subspace was extracted from the full-factorial parameter space for batch-size synthesis optimization. The subsequent Bayesian optimizer was hereby able to traverse the subspace and locate a recipe giving large uniform particles (>10 µm). This highly flexible and efficient strategy can be extended to a diverse library of reactions beyond microsphere synthesis.

A graph-convolutional neural network for addressing small-scale reaction prediction.

We describe a graph-convolutional neural network (GCN) model, the reaction prediction capabilities of which are as potent as those of the transformer model based on sufficient data, and we adopt the Baeyer-Villiger oxidation reaction to explore their performance differences based on limited data. The top-1 accuracy of the GCN model (90.4%) is higher than that of the transformer model (58.4%).

A Single Small-Scale Plutonium Redox Reaction System Yields Three Crystallographically-Characterizable Organoplutonium Complexes.

An approach to obtaining substantial amounts of data from a hazardous starting material that can only be obtained and handled in small quantities is demonstrated by the investigation of a single small-scale reaction of cyclooctatetraene, C8H8, with a solution obtained from the reduction of Cp'3Pu (Cp' = C5H4SiMe3) with potassium graphite. This one reaction coupled with oxidation of a product has provided single-crystal X-ray structural data on three organoplutonium compounds as well as information on redox chemistry thereby demonstrating an efficient route to new reactivity and structural information on this highly radioactive element. The crystal structures were obtained from the reduction of C8H8 by a putative Pu(II) complex, (Cp'3PuII)1-, generated in situ, to form the Pu(III) cyclooctatetraenide complex, [K(crypt)][(C8H8)2PuIII], 1-Pu, and the tetra(cyclopentadienyl) Pu(III) complex, [K(crypt)][Cp'4PuIII], 2-Pu. Oxidation of the sample of 1-Pu with Ag(I) afforded a third organoplutonium complex that has been structurally characterized for the first time, (C8H8)2PuIV, 3-Pu. Complexes 1-Pu and 3-Pu contain Pu sandwiched between parallel (C8H8)2- rings. The (Cp'4PuIII)- anion in 2-Pu features three η5-Cp' rings and one η1-Cp' ring, which is a rare example of a formal Pu-C η1-bond. In addition, this study addresses the challenge of small-scale synthesis imparted by radiological and material availability of transuranium isotopes, in particular that of pure metal samples. A route to an anhydrous Pu(III) starting material from the more readily available PuIVO2 was developed to facilitate reproducible syntheses and allow complete spectroscopic analysis of 1-Pu and 2-Pu. PuIVO2 was converted to PuIIIBr3(DME)2 (DME = CH3OCH2CH2OCH3) and subsequently PuIIIBr3(THF)x, which was used to independently synthesize 1-Pu, 2-Pu, and 3-Pu.

Thermal hazard analysis of a biomass pretreatment process using ionic liquids

Ionic liquids (ILs) may have various applications as less hazardous solvents because of their thermal stabilities and low vapor pressures. However, it is challenging to remove heat from large amount because of IL’s high viscosity and low vapor pressure when cooling failure or abnormal reaction occurs. Because chemical processes using ILs on an industrial scale are still in the early phase of development, it is important to assess the associated thermal hazards of chemical process using ILs. This work proposes a systematic approach of analyzing thermal hazards of chemical process using ILs, based on the approach proposed by Stoessel and analyze the cellulose dissolution process using ILs containing impurities as a test case. Copper oxide, which might be contaminated from wood chips, was chosen as a model impurity. To analyze the thermal hazards of cellulose dissolution process using ILs, thermal analysis using small-scale reaction calorimeter, differential scanning calorimeter and thermogravimetry–differential thermal analysis–mass spectrometry were performed. From these results, reaction heat and heat value of ILs and its mixture were low, while CuO lowers the decomposition temperature of ILs and produces flammable gases. From these trials, exothermal reaction was not observed, while flammable gaseous products might be produced in vapor phase in the reactor.

Stabilization and scale-up of photosynthesis-driven ω-hydroxylation of nonanoic acid methyl ester by two-liquid phase whole-cell biocatalysis.

Photoautotrophic organisms are promising hosts for biocatalytic oxyfunctionalizations because they supply reduction equivalents as well as O2 via photosynthetic water oxidation. Thus far, research on photosynthesis-driven bioprocesses mainly focuses on strain development and the proof of principle in small-scale biocatalytic reaction setups. This study investigates the long-term applicability of the previously developed cyanobacterial strain Synechocystis sp. PCC 6803_BGT harboring the alkane monooxygenase system AlkBGT catalyzing terminal alkyl group oxyfunctionalization. For the regiospecific ω-hydroxylation of nonanoic acid methyl ester (NAME), this biocatalyst showed light intensity-independent hydroxylation activity and substantial hydrolysis of NAME to nonanoic acid. Substrate mass transfer limitation, substrate hydrolysis, as well as reactant toxicity were overcome via in situ substrate supply by means of a two-liquid phase system. The application of diisononyl phthalate as organic carrier solvent enabled 1.7-fold increased initial specific activities (5.6 ± 0.1 U/gCDW ) and 7.6-fold increased specific yields on biomass (3.8 ± 0.1 mmolH-NAME /gCDW ) as compared with single aqueous phase biotransformations. Finally, the whole-cell biotransformation system was successfully scaled from glass tubes to a stirred-tank photobioreactor. This is the first study reporting the application of the two-liquid phase concept for efficient phototrophic whole-cell biocatalysis.

Polymer-based controlled-release fed-batch microtiter plate \u2013 diminishing the gap between early process development and production conditions

BackgroundFed-batch conditions are advantageous for industrial cultivations as they avoid unfavorable phenomena appearing in batch cultivations. Those are for example the formation of overflow metabolites, catabolite repression, oxygen limitation or inhibition due to elevated osmotic concentrations. For both, the early bioprocess development and the optimization of existing bioprocesses, small-scale reaction vessels are applied to ensure high throughput, low costs and prompt results. However, most conventional small-scale procedures work in batch operation mode, which stands in contrast to fed-batch conditions in large-scale bioprocesses. Extensive expenditure for installations and operation accompany almost all cultivation systems in the market allowing fed-batch conditions in small-scale. An alternative, more cost efficient enzymatic glucose release system is strongly influenced by environmental conditions. To overcome these issues, this study investigates a polymer-based fed-batch system for controlled substrate release in microtiter plates.ResultsImmobilizing a solid silicone matrix with embedded glucose crystals at the bottom of each well of a microtiter plate is a suitable technique for implementing fed-batch conditions in microtiter plates. The results showed that the glucose release rate depends on the osmotic concentration, the pH and the temperature of the medium. Moreover, the applied nitrogen source proved to influence the glucose release rate. A new developed mathematical tool predicts the glucose release for various media conditions. The two model organisms E. coli and H. polymorpha were cultivated in the fed-batch microtiter plate to investigate the general applicability for microbial systems. Online monitoring of the oxygen transfer rate and offline analysis of substrate, product, biomass and pH confirmed that fed-batch conditions are comparable to large-scale cultivations. Furthermore, due to fed-batch conditions in microtiter plates, product formation could be enhanced by the factor 245 compared to batch cultivations.ConclusionsThe polymer-based fed-batch microtiter plate represents a sophisticated and cost efficient system to mimic typical industrial fed-batch conditions in small-scale. Thus, a more reliable strain screening and early process development can be performed. A systematical scale-down with low expenditure of work, time and money is possible.

Establishing a Cell-Free Vibrio natriegens Expression System

The fast growing bacterium Vibrio natriegens is an emerging microbial host for biotechnology. Harnessing its productive cellular components may offer a compelling platform for rapid protein production and prototyping of metabolic pathways or genetic circuits. Here, we report the development of a V. natriegens cell-free expression system. We devised a simplified crude extract preparation protocol and achieved >260 μg/mL of superfolder GFP in a small-scale batch reaction after 3 h. Culturing conditions, including growth media and cell density, significantly affect translation kinetics and protein yield of extracts. We observed maximal protein yield at incubation temperatures of 26 or 30 °C, and show improved yield by tuning ions crucial for ribosomal stability. This work establishes an initial V. natriegens cell-free expression system, enables probing of V. natriegens biology, and will serve as a platform to accelerate metabolic engineering and synthetic biology applications.

Molecular-level modeling investigation of n-decane pyrolysis at high temperature

A small-scale molecular reaction model has been established to predict the behavior of thermal cracking n-decane based on the experimental study of n-decane pyrolysis under supercritical conditions (4MPa, 480–720°C). A developed experimental method of electrical heating tube (2mm inner diameter) was used experimentally to obtain the detailed local chemical compositions and temperatures along the reactor tube. Gas chromatography was used to analysis the pyrolysis products, and the calculated density and corresponding residence times along the reactor tube were reported. The overall n-decane decomposition could be represented by a first-order reaction with frequency factor and activation energy of 6.209×1015s−1 and 59.4kcal/mol, respectively. The experimental products and calculated thermophysical properties along the microchannels of a heat exchanger could be effectively simulated by using the molecular reaction model, consisting of 16 species, a first-order reaction and 21 secondary reactions among the primary products. The performance of the reaction model in reproducing the experimental data was reasonably good even the cracking conversion up to 93%.

Empirical Approach to Small-Scale Reaction Mechanism for Regular Gasoline Surrogate Fuel

Empirical Approach to Small-Scale Reaction Mechanism for Regular Gasoline Surrogate Fuel

Random mutagenesis of the hyperthermophilic archaeon Pyrococcus furiosus using in vitro mariner transposition and natural transformation.

Transposition mutagenesis is a powerful tool to identify the function of genes, reveal essential genes and generally to unravel the genetic basis of living organisms. However, transposon-mediated mutagenesis has only been successfully applied to a limited number of archaeal species and has never been reported in Thermococcales. Here, we report random insertion mutagenesis in the hyperthermophilic archaeon Pyrococcus furiosus. The strategy takes advantage of the natural transformability of derivatives of the P. furiosus COM1 strain and of in vitro Mariner-based transposition. A transposon bearing a genetic marker is randomly transposed in vitro in genomic DNA that is then used for natural transformation of P. furiosus. A small-scale transposition reaction routinely generates several hundred and up to two thousands transformants. Southern analysis and sequencing showed that the obtained mutants contain a single and random genomic insertion. Polyploidy has been reported in Thermococcales and P. furiosus is suspected of being polyploid. Yet, about half of the mutants obtained on the first selection are homozygous for the transposon insertion. Two rounds of isolation on selective medium were sufficient to obtain gene conversion in initially heterozygous mutants. This transposition mutagenesis strategy will greatly facilitate functional exploration of the Thermococcales genomes.