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Transportation of magnetized particles (MPs) against gravity is possible by applying a magnetic field to the particles. This transport phenomenon of MPs in microdroplets can be quantitatively assessed by determining the contribution of individual forces acting on the MPs. We studied the selective transportation of MPs in microdroplets. MPs in microdroplets were transported in the opposite direction to gravity when we applied an external magnetic field larger than a threshold value. We modulated the intensity of the external magnetic field and selectively manipulated the MPs. As a result, MPs were separated into different microdroplets based on their magnetic properties. Our quantitative investigation of transport dynamics shows that the threshold magnetic field depends only on the magnetic susceptibility and the density of MPs. This is a universal criterion for the selective transport of magnetized targets such as magnetized cells in microdroplets. [ABSTRACT FROM AUTHOR]

The ozone (O3) oxidation kinetics of cysteine in aqueous micro‐droplets at different acidities is investigated in this study via aerosol optical tweezers coupled with Raman spectroscopy. This study exploits the O3 oxidation of cysteine near the interface of micro‐droplets as a model system to elucidate the oxidation damage of amino acids in biosurfaces. For each optically trapped micro‐droplet, Raman spectroscopy is used to determine its droplet radius, concentrations of solutes, and droplet pH, as well as their time evolutions during the kinetics measurements. The bimolecular rate coefficients of the cysteine + O3 reaction measured in micro‐droplets are around 4 × 105 M−1 s−1 and 2 × 104 M−1 s−1 for pH ≈ 5 and 0.5, respectively. These results agree with the previous bulk measurements, indicating that the observed aerosol kinetics can be solely rationalized via diffusion‐limited kinetics. The results also indicate that a high‐ionic strength could enhance the cysteine + O3 reaction, particularly for the zwitterion form of cysteine. The results imply that when surfactant proteins in lung fluids are exposed to ambient O3, the cysteine residues in proteins will be attacked by O3 at first due to the high reactivity of the thiol moiety in cysteine. [ABSTRACT FROM AUTHOR]

Late‐stage diversification of drug molecules is an important strategy in drug discovery that can be facilitated by reaction screening using high‐throughput experimentation. Here we present a rapid method for functionalizing bioactive molecules based on accelerated reactions in microdroplets. Reaction mixtures are nebulized at throughputs better than 1 reaction/second and the accelerated reactions occurring in the microdroplets are followed by desorption electrospray ionization mass spectrometry (DESI‐MS). Because the accelerated reactions occur on the millisecond timescale, they allow an overall screening throughput of 1 Hz working at the low nanogram scale. Using this approach, an opioid agonist (PZM21) and an antagonist (naloxone) were diversified using three reactions important in medicinal chemistry: sulfur fluoride exchange (SuFEx) click reactions, imine formation reactions, and ene‐type click reactions. Some 269 functionalized analogs of naloxone and PZM21 were generated and characterized by tandem mass spectrometry (MS/MS) after screening over 500 reactions. [ABSTRACT FROM AUTHOR]

Spontaneous emulsification, resulting from the assembly and accumulation of surfactants at liquid–liquid interfaces, is an interfacial instability where microdroplets are generated and diffusively spread from the interface until complete emulsification. Here, it is shown that an external magnetic field can modulate the assembly of paramagnetic nanoparticle surfactants (NPSs) at liquid–liquid interfaces to trigger an oversaturation in the areal density of the NPSs at the interface, as evidenced by a marked reduction in the interfacial tension, γ, and corroborated with a magnetostatic continuum theory. Despite the significant reduction in γ, the presence of the magnetic field does not cause stable interfaces to become unstable. Upon rapid removal of the field, however, an explosive ejection of a plume of microdroplets from the surface occurs, a dynamical interfacial instability which is termed explosive emulsification. This explosive event rapidly reduces the areal density of the NPSs to its pre‐field level, stabilizing the interface. The ability to externally suppress or trigger the explosive emulsification and controlled generation of tens of thousands of microdroplets, uncovers an efficient energy storage and release process, that has potential applications for controlled and directed delivery of chemicals and remotely controlled soft microrobots, taking advantage of the ferromagnetic nature of the microdroplets. [ABSTRACT FROM AUTHOR]

Microdroplet screening of microorganisms can improve the rate of strain selection and characterization within the canonical design–build–test paradigm. However, a full analysis of the microdroplet environment and how well these conditions translate to culturing conditions and techniques is lacking in the field. Quantification of three different biosensor/analyte combinations at 12 hour timepoints reveals the potential for extended dose–response ranges as compared to traditional in vitro conditions. Using these dynamics, we present an application and analysis of microfluidic droplet screening utilizing whole-cell biosensors, ultimately identifying an altered productivity profile of itaconic acid in a Yarrowia lipolytica-based piggyBac transposon library. Specifically, we demonstrate that the timepoint for microdroplet selection can influence the outcome of the selection and thus shift the identified strain productivity and final titer. In this case, strains selected at earlier timepoints showed increased early productivity in flask scale, with the converse true as well. Differences in response indicate microdroplet assays require tailored development to more accurately sort for phenotypes that are scalable to larger incubation volumes. Likewise, these results further highlight that screening conditions are critical parameters for success in high-throughput applications. [ABSTRACT FROM AUTHOR]

Fabricating controllable superhydrophobic surfaces remains challenging in various fields ranging from chemical industries to biomedical engineering. Conventional methods commonly require volatile organic solvents and the assistance of special surface deposition and modification equipment, which are detrimental to environment and limit their applications in micro‐devices. Herein, an equipment‐free method is reported to directly transform fluorinated monomer micro‐droplets into hydrophobic polymer particles on flat substrate surfaces in water, simultaneously depositing hydrophobic coatings with tunable surface structures. The as‐prepared surfaces show superior superhydrophobicity and great stability in extreme conditions (e.g., varying acidity, basicity, and heating conditions), and excellent anti‐fouling property. Meanwhile, surface hydrophobicity can be manipulated by adjusting emulsion droplet number density and reaction time. Hence, superhydrophobic surfaces with tunable hydrophobicity gradients have been successfully fabricated in one pot. This study provides an equipment‐free method to facilely fabricate controllable superhydrophobic surfaces, with great potential in the development of smart superhydrophobic materials in various engineering and industrial applications. [ABSTRACT FROM AUTHOR]

An ideally flexible laser may function in unison with minute fluctuations in nature. Lasers made solely from liquids are promising toward this end, but they are intrinsically unstable and have been inapplicable to steady operation under ambient conditions unless they are enclosed in a tailored container or a matrix to prevent the evaporation of the liquid. Here, a simple methodology is reported to form a self‐standing spherical microlaser that is composed fully of liquid and operates steadily even under atmosphere. The robustness and spherical morphology of the droplets are achieved by using ionic liquid as the liquid medium and gently casting the droplets on a substrate covered with hydrophobic nanoparticles to enhance the metastability of the contact angle. The resulting droplets are highly robust and work as efficient long‐lasting laser oscillators. The lasing wavelength is sensitively shifted when the droplets are subjected to a faint breeze or moisture, which is associated with the deformation of the droplet. The morphological and optical responses of the droplet under gas convection are consistently supported by aerodynamic and electromagnetic simulations. The droplets are readily scalable with an inkjet printer without the need for any further treatments. [ABSTRACT FROM AUTHOR]

We present a simple optical capability for generating spatially resolved chemical concentration maps of mixing fluids using a chemically sensitive dye, 1-hydroxy-3,6,8-pyrenetrisulfonic acid, detected by planar laser induced fluorescence. To demonstrate an application of this capability, we investigate the collision and mixing of a pair of microdroplets in air. The two microdroplets are composed of different fluids, methanol and water, with the dye initially in the methanol droplet. When the droplets collide and mixing process develops, the fluorescence of the dye shifts from blue to green as the solvent environment changes. A series of spectral-temporal images of the collision and subsequent mixing are recorded, from which we extract the distribution of the two intermixing droplet species reflected in the spatially resolved dye spectra. Images reveal material transfer between droplets in both coalescing and non-coalescing droplet collisions. [ABSTRACT FROM AUTHOR]

Water microdroplets containing organic and fluorinated compounds, such as formate, perfluorooctanoic acid (PFOA) and triflic acid, were exposed to a radiofrequency glow discharge plasma with a droplet residence time on the order of milliseconds. Triflic acid remained unaffected by any plasma condition while >75% decomposition of formate and PFOA could be achieved. In situ hydroxyl (OH)‐laser‐induced fluorescence measurements near the droplets confirmed that the conversion was independent of the OH flux to the droplet. A series of control experiments suggest that the contribution of vacuum UV photons in such decomposition of aqueous compounds can be significant for He and He + 17% Ar plasmas and can also explain unexpected decomposition trends as a function of droplet residence time in the plasma. [ABSTRACT FROM AUTHOR]

Microforce plates are indispensable tools for quantitatively evaluating the behavior of small objects such as tiny insects or microdroplets. The two main measurement principles for microforce plates are: the formation of strain gauges on the beam that supports the plate and the measurement of the deformation of the plate using an external displacement meter. The latter method is characterized by its ease of fabrication and durability as strain concentration is not required. To enhance the sensitivity of the latter type of force plates with a planar structure, thinner plates are generally desired. However, brittle material force plates that are both thin and large and can be fabricated easily have not yet been developed. In this study, a force plate consisting of a thin glass plate with a planar spiral spring structure and a laser displacement meter placed under the plate center is proposed. The plate deforms downward when a force is exerted vertically on its surface, resulting in the determination of the applied force using Hooke's law. The force plate structure is easily fabricated by laser processing combined with the microelectromechanical system (MEMS) process. The fabricated force plate has a radius and thickness of 10 mm and 25 µm, respectively, with four supporting spiral beams of sub-millimeter width. A fabricated force plate featuring a sub-N/m spring constant achieves a resolution of approximately 0.01 µN. [ABSTRACT FROM AUTHOR]

Purpose: Micron-sized perfluorocarbon droplet adjuvants to focused ultrasound therapies allow lower applied power, circumvent unwanted prefocal heating, and enhance thermal dose in highly perfused tissues. The heat enhancement has been shown to saturate at increasing concentrations. Experiments were performed to empirically model the saturating heating effects during focused ultrasound. Materials and methods: The measurements were made at varying concentrations using magnetic resonance thermometry and focused ultrasound by circulating droplets of mean diameter 1.9 to 2.3 µm through a perfused phantom. A simulation was performed to estimate the interaction radius size, empirically. Results: The interaction radius, representing the radius of a sphere encompassing 90% of the probability for the transformation of acoustic energy into heat deposition around a single droplet, was determined experimentally from ultrasonic absorption coefficient measurements The simulations suggest the interaction radius was approximately 12.5-fold larger than the geometrical radius of droplets, corresponding to an interaction volume on the order of 2000 larger than the geometrical volume. Conclusions: The results provide information regarding the dose–response relationship from the droplets, a measure with 15% precision of their interaction radii with focused ultrasound, and subsequent insights into the underlying physical heating mechanism.

Water (H2O) microdroplets are sprayed onto a magnetic iron oxide (Fe3O4) and Nafion-coated graphite mesh using compressed N2 or air as the nebulizing gas. The resulting splash of microdroplets enters a mass spectrometer and is found to contain ammonia (NH3). This gas–liquid–solid heterogeneous catalytic system synthesizes ammonia in 0.2 ms. The conversion rate reaches 32.9 ± 1.38 nmol s−1 cm−2 at room temperature without application of an external electric potential and without irradiation. Water microdroplets are the hydrogen source for N2 in contact with Fe3O4. Hydrazine (H2NNH2) is also observed as a by-product and is suspected to be an intermediate in the formation of ammonia. This one-step nitrogen-fixation strategy to produce ammonia is eco-friendly and low cost, which converts widely available starting materials into a value-added product. [ABSTRACT FROM AUTHOR]

The precise control of tiny droplets has always been a complex problem to be solved. The magnetically responsive superhydrophobic surfaces, which can be controlled for droplet manipulation by an external magnetic field, have attracted attention because of its characteristics such as easy operation, rapid response, remote control, and simple process. Herein, a magnetically responsive superhydrophobic surface is designed and prepared by a two‐step spraying process. The precise control of microdroplets on the prepared surface is carried out, and the droplet control can be quickly achieved through noncontact control in various ways including active, multidirectional, and antigravity. On this basis, the ideal surface model is established to analyze the droplet control mechanism. In addition, the transport effects of different types of droplets, including water droplets and saline, are investigated. The durability evaluation experiment including droplet‐repeated control, friction, tape stripping, and scratch test shows that the surface has certain durability. This magnetically responsive superhydrophobic surfaces can meet requirements of biological experiments and provide a new idea for low‐loss droplet transport and microfluidic chip. [ABSTRACT FROM AUTHOR]

This work reports the formation of silver nanoparticles (AgNPs) by sputter deposition in thin films of three different ionic liquids (ILs) with the same anion (bis(trifluoromethylsulfonyl)imide) and cation (imidazolium), but with different alkyl chain lengths and symmetries in the cationic moiety ([C4C1im][NTf2], [C2C2im][NTf2], and [C5C5im][NTf2]). Ionic liquid (IL) films in the form of microdroplets with different thicknesses (200 to 800 monolayers) were obtained through vacuum thermal evaporation onto glass substrates coated with indium tin oxide (ITO). The sputtering process of the Ag onto the ILs when conducted simultaneously with argon plasma promoted the coalescence of the ILs' droplets and the formation, incorporation, and stabilization of the metallic nanoparticles in the coalesced IL films. The formation/stabilization of the AgNPs in the IL films was confirmed using high-resolution scanning electron microscopy (SEM) and UV-Vis spectroscopy. It was found that the IL films with larger thicknesses (600 and 800 monolayers) were better media for the formation of AgNPs. Among the ILs used, [C5C5im][NTf2] was found to be particularly promising for the stabilization of AgNPs. The use of larger IL droplets as capture media was found to promote a better stabilization of the AgNPs, thereby reducing their tendency to aggregate. [ABSTRACT FROM AUTHOR]

A numerical investigation of the deformation of compound microdroplets transported inside a circular microchannel is described in this article. Two droplet morphologies are considered (shell-core and Janus), which correspond to nonequilibrium and equilibrium states, respectively, based on the balancing of the three interfacial tensions at the triple line. Numerical simulations coupled with a three-phase volume-of-fluid method are performed on axisymmetric models to consider both the absence and presence of a triple line. In addition to adaptive mesh refinement on the interfaces, topology-oriented refinement is used to resolve thin films between the shell and core droplets. After experimental validation, the effects of flow rates, physical properties, and confinement conditions are considered. In the reference frame of the droplets, there are five inner vortexes inside the shell-core droplet, while only three are present inside the Janus droplet, the same as single-phase droplets. For shell-core droplets, the aspect ratio of the shell droplet decreases with the capillary number of the continuous phase and droplet sizes, while sudden jumps are identified when the thin film forms between the shell and core interfaces. Conversely, the aspect ratio of the core droplet increases and then decreases when the shape of the core droplets is influenced by the flow and space confinements. With Janus droplets, the aspect ratio decreases with the capillary number. The axial length of the front portion decreases with the capillary number and then reaches a plateau with small variations, while that of the rear portion increases nearly linearly. [ABSTRACT FROM AUTHOR]

[Display omitted] Droplet spreading governs various daily phenomena and industrial processes. Insights about microdroplet spreading are limited due to experimental difficulties arising from microdroplet manipulation and substrate wettability control. For droplet sizes approaching the capillary length scale, the gravitational force plays an important role in spreading. In contrast, capillary and viscous forces dominate as the droplet size reduces to smaller length scales. We hypothesize that the dynamic spreading behavior of microdroplets whose radius is far lower than the capillary length differs substantially from established and well understood dynamics. To systematically investigate the spreading dynamics of microdroplets, we develop contact-initiated wetting techniques combined with structuring-independent wettability control to achieve microdroplet (<500 μm) spreading on arbitrary surfaces while eliminating parasitic pinning effects (pining force ∼ 0) and initial impact momentum effects (Weber number ∼ 0). Our experiments reveal that the capillary-driven initial spreading of microdroplets is shorter, with significantly reduced oscillation dampening, when compared to millimeter-scale droplets. Furthermore, spreading along with capillary wave propagation results in coupling between the spreading velocity and dynamic contact angle at the contact line. These findings, along with our proposed microdroplet manipulation platform, may find application in microscale heat transfer, advanced manufacturing, and aerosol transmission studies. [ABSTRACT FROM AUTHOR]

Currently, coaxial electrohydrodynamic jet (CE-Jet) printing is used as a promising technique for the alternative fabrication of drop-on-demand micro- and nanoscale structures without using a template. Therefore, this paper presents numerical simulation of the DoD CE-Jet process based on a phase field model. Titanium lead zirconate (PZT) and silicone oil were used to verify the numerical simulation and the experiments. The optimized working parameters (i.e., inner liquid flow velocity 150 m/s, pulse voltage 8.0 kV, external fluid velocity 250 m/s, print height 16 cm) were used to control the stability of the CE-Jet, avoiding the bulging effect during experimental study. Consequently, different sized microdroplets with a minimum diameter of ~5.5 µm were directly printed after the removal of the outer solution. The model is considered the easiest to implement and is powerful for the application of flexible printed electronics in advanced manufacturing technology. [ABSTRACT FROM AUTHOR]

With the advent of many optofluidic and droplet microfluidic applications using laser-induced fluorescence (LIF), the need for a better understanding of the heating effect induced by pump laser excitation sources and good monitoring of temperature inside such confined microsystems started to emerge. We developed a broadband highly sensitive optofluidic detection system, which enabled us to show for the first time that Rhodamine-B dye molecules can exhibit standard photoluminescence as well as blue-shifted photoluminescence. We demonstrate that this phenomenon originates from the interaction between the pump laser beam and dye molecules when surrounded by the low thermal conductive fluorocarbon oil, generally used as a carrier medium in droplet microfluidics. We also show that when the temperature is increased, both Stokes and anti-Stokes fluorescence intensities remain practically constant until a temperature transition is reached, above which the fluorescence intensity starts to decrease linearly with a thermal sensitivity of about − 0.4 % / ° C for Stokes emission or − 0.2 % / ° C for anti-Stokes emission. For an excitation power of 3.5 mW, the temperature transition was found to be about 25 ° C, whereas for a smaller excitation power (0.5 mW), the transition temperature was found to be about 36 ° C. [ABSTRACT FROM AUTHOR]

Novel strategies to combat dental biofilms aim at reducing biofilm stability with the ultimate goal of facilitating mechanical cleaning. To test the stability of dental biofilms, they need to be subjected to a defined mechanical stress. Here, we employed an oral care device (Airfloss) that emits microbursts of compressed air and water to apply a defined mechanical shear to 14-day-old dental plaque in 20 healthy participants with no signs of oral diseases (clinical trial no. NCT05082103). Exclusion criteria included pregnant or nursing women, users of oral prostheses, retainers or orthodontic appliances, and recent antimicrobial or anti-inflammatory therapy. Plaque accumulation, before and after treatment, was assessed using fluorescence images of disclosed dental plaque on the central incisor, first premolar, and first molar in the third quadrant (120 images). For each tooth, the pre- and post-treatment plaque percentage index (PPI) and Turesky modification of the Quigley-Hein plaque index (TM-QHPI) were recorded. The mean TM-QHPI significantly decreased after treatment (p = 0.03; one-sample sign test), but no significant difference between the mean pre- and post-treatment PPI was observed (p = 0.09; one-sample t-test). These data are of value for researchers that seek to apply a defined mechanical shear to remove and/or disrupt dental biofilms. Dataset: The dataset is submitted as a supplementDataset License: CC-BY-NC [ABSTRACT FROM AUTHOR]

Microalgae are essential sources of biofuels and bio-products, and usually they are studied using "bulk" technologies that ignore the heterogeneity of cells as well as the importance of single cell-based phenomena. As a consequence, being able to culture, monitor, and study single or a small amount of algal cells is important for investigating how the stochasticity of separate cells affects a population of them. Micro-droplets, micro-scaled aqueous droplets suspended in the oil phase, provide an excellent platform for investigating individual microalgae. They offer advantages of independence, small volume, mono-dispersion, high surface-area-to-volume ratio, and high throughput. In this study, a microfluidic device is designed and fabricated to generate micro-droplets for encapsulating microalgae of different culture media. The channel dimension and the flow rates of both aqueous and oil phases are adjusted based on simulation results to experimentally generate microdroplets of similar sizes. This chip is then used to study how culture conditions, including various concentrations of nutrient solution, nitrogen (urea) and ion (Cu2+), affect the growth of microalgae Chlorella vulgaris in a high-throughput manner. After 10 days of culturing and monitoring, the results show that, in general, the presence of nutrient solution and urea at optimal concentrations stimulates the growth of Chlorella vulgaris, while medium containing Cu2+ suppresses its growth. These findings can definitely help in optimizing the growth condition of microalgae for increasing their yields as resources of bio-products and biofuels. [ABSTRACT FROM AUTHOR]

The precision and consistency of the microdroplet jetting procedure are crucial for the casting sand mold's performance during binder injection. The generation and jetting of microdroplets in piezoelectric printheads were examined in this study in relation to changes in specific jetting process parameters. Using finite element analysis and a simplified physical model of a microdroplet jetting device, an electromechanically coupled model of a microdroplet jetting device was created in order to study the characteristics of microdroplet jetting. A volume-of-fluid model was also created in order to study the microdroplet jetting process and perform repeatability tests. The effects of altering nozzle radius, actuation pulse width, intake velocity, and fluid viscosity on microdroplet jetting properties were then investigated using the models. We were able to control the development of satellite droplets thanks to the knowledge we gained about how each process parameter affected droplet status. This study demonstrates how the radius of the nozzle and the pulse width of the piezoelectric actuation signal have a significant impact on the jetting properties of piezoelectric printheads and the production of microdroplets. The quantitative correlations between process factors and jetting characteristics can be used to optimize microdroplet production and reduce droplet size. Finally, this study will help create control systems for microdroplet jetting operations and enhance the precision of 3D printed casting sand molds. [ABSTRACT FROM AUTHOR]

Research on the microdroplet splitting phenomenon has intensified in recent years. Microdroplet splitting has numerous applications in chemical synthesis, biology, and separation processes. The current paper covers the numerical study of ferrofluid microdroplet splitting at various lengths and velocities inside the T-junction with branches of unequal widths under asymmetric magnetic fields. Microdroplet splitting can be controlled by using an asymmetric magnetic field and the asymmetry in the width of T-junctions branches. Three geometrical models of the T-junction with different widths ratio (0.7, 0.85, and 1), along with a magnetic field with various intensities are studied. This magnetic field is generated by a line dipole. In this study, the distance between the dipole and origin is kept constant. The splitting ratio of ferrofluid microdroplets at different velocities (different capillary numbers), different non-dimensional lengths and different magnetic force (different magnetic Bond numbers) at the center of T-junction are calculated for each amount of branch width. The results are verified with previous works and their correctness is proved. The splitting ratio is defined as the volumetric ratio of the larger daughter droplet to the mother droplet. The results indicate that generally, the stronger the asymmetric magnetic force is, the more asymmetric the splitting will become, with the splitting ratio becoming closer to 1. Also, as asymmetry increases between the widths of the two branches of the Tjunction, the splitting ratio approaches 1. [ABSTRACT FROM AUTHOR]

[Display omitted] Phospholipids are the protective layer of modern cells, but it is challenging for the formation of phospholipids that require a simple abiotic synthesis before the advent of primitive cells. Here, we reported the abiotic synthesis for lysophosphatidic acids (LPAs) with prebiotically plausible reactants in aqueous microdroplets under ambient conditions. The LPAs formation is carried out by fusing two microdroplets streams: one contains glycerol and pyrophosphate in water and the other one contains fatty acids in acetonitrile. Compared with the bulk solution, LPAs were generated in microdroplets without the addition of catalyst and heating. Conditions of reactant concentrations and microdroplet size varied and suggested that LPAs formation occurred near or at the microdroplet surface. The LPAs formation also showed chemoselective toward on chain-length of fatty acids. Finally, the formation of LPAs underwent two-step reactions with glycerol phosphorylation eliminating one water molecule followed by esterification with fatty acids. These results also implicated that pyrophosphate functioned as both catalysts and precursors in prebiotic LPAs synthesis. The approach using fusion aqueous microdroplets has desirable features in studying the substance exchange and interaction in atmosphere. [ABSTRACT FROM AUTHOR]

Microdroplets have many unique features derived from the large surface-volume ratio and the ultrahigh electric field at the air-water interface, therefore they can remarkably accelerate various slow reactions and trigger reactions that won’t occur in bulk solutions. The size of atmospheric aerosols is similar to that of the microdroplets, so reactions performed in microdroplets and ambient conditions can act as good simulations of important atmospheric processes, which will provide a better understanding of the role of aerosols. Aldehydes are important oxidized species in the atmosphere derived from releases of human activities, such as vehicle emissions and biomass burning, which can generate volatile organic compounds (VOCs) and are highly related to salt-rich aerosol formation through further oxidation. Studying of aldehydes’ hydration and oxidation reactions is very helpful for understanding the complex conversion process from VOCs to secondary organic aerosols (SOA). In this work, several aromatic aldehydes with different electron donating or withdrawing groups were studied by spraying their solutions into microdroplets, then directly characterizing them by online mass spectrometry. It showed that these aromatic aldehydes could be oxidized into carboxylic acids under the space-restricting condition of microdroplets, and the hydration reactions of aromatic aldehydes could be induced by carboxylate under the extreme pH environment and abundant reactive oxygen species provided by the air-water interface of microdroplets. Together, the products of oxidation and hydration reactions would combine to yield relatively unstable “carboxylate-aldehyde hydrate” complex ions. The lifetime of the ions was roughly estimated by conducting a collision-induced disassociation (CID) experiment and comparing it to the instrument running procedure, and the structure was checked using CID and a cross-forming reaction between two different aldehydes. This work revealed that the complex ions were potential intermediates of the atmospheric aldehyde oxidation reaction, providing a previously unknown pathway of atmospheric carboxylic acids and SOA. This result supported the view that atmospheric oxidation might take place in aerosols, such as fog and clouds, which was the missing part of SOA sources and matched the observations. However, unlike other liquid phase or gaseous simulation research of the oxidation process of aldehydes, the oxidation reaction would occur even without the participation of UVs or hydrogen peroxide addition in microdroplets, because the air-water interface could generate a large number of reactive oxygen species (ROS) like hydroxyl radicals and hydrogen peroxide, implicating that the air-water interface of aerosols might be an important place to perform many atmospheric reactions. [ABSTRACT FROM AUTHOR]

We presented a microfluidic device for the preparation of monodisperse microdroplets with a small volume of samples or reagents, which is power-free, user-friendly and based only on a highly portable syringe. Our method requires only hand-operated syringes and sharpened capillaries without any complicated experimental setups, making the entire system portable and user-friendly for non-technical users. Vacuum is generated by pulling the plunger of the syringe on site, and fluid is generated by vacuum. The droplet size can be flexibly controlled by adjusting the size of micropores and capillary or vacuum degree. More potentially, microliter samples or reagents can also be prepared from it into emulsions. Unlike traditional methods, our device is self-activated, avoiding the need for external power supply while ensuring fewer samples or reagents consumption, simplifying operations and saving costs, facilitating immediate diagnostic testing or field trace substance detection. [ABSTRACT FROM AUTHOR]

In this study, artificial microparticles were used as pseudo-cells to select samples that can be used as substitutes for micro-droplet injection nebulizer (M-DIN) ICP-MS standards. The microparticles were selected on the basis that they should be comparable in size to human cells, have a small deviation in volume, and have different elemental contents and pyrolysis properties. Polymer latex particles, magnetic latex particles, borosilicate glass particles, and straight polymethyl methacrylate particles were used. As a result, we succeeded in detecting the contained elements in polymer latex, magnetic latex and polymethyl methacrylate particles. In addition, focusing on Mg contained in all particles, we compared the correlation between the mass signal intensity by droplet ICP-MS and the average elemental content in a particle. [ABSTRACT FROM AUTHOR]

We present immunoassay‐based desorption electrospray ionization mass spectrometry imaging (immuno‐DESI‐MSI) to visualize functional macromolecules such as drug targets and cascade signaling factors. A set of boronic acid mass tags (BMTs) were synthesized to label antibodies as MSI probes. The boronic ester bond is employed to cross‐link the BMT with the galactosamine‐modified antibody. The BMT can be released from its tethered antibody by ultrafast cleavage of the boronic ester bond caused by the acidic condition of sprayed DESI microdroplets containing water. The fluorescent moiety enables the BMT to work in both optical and MS imaging modes. The positively charged quaternary ammonium group enhances the ionization efficiency. The introduction of the boron element also makes mass tags readily identified because of its unique isotope pattern. Immuno‐DESI‐MSI provides an appealing strategy to spatially map macromolecules beyond what can be observed by conventional DESI‐MSI, provided antibodies are available to the targeted molecules of interest. [ABSTRACT FROM AUTHOR]

Currently, developing disinfectant materials is of utmost importance. A significant advantage of our fabric is its reusability. The disinfectants based on a natural polymer of cellulose have been barely investigated. Our work presents a modified cellulose material, and the data obtained for the first time on the chlorine dioxide generation process when treating the material with a sodium chlorite alcohol solution. A method of applying NaClO2 onto the fabric by impregnating it with a solution sprayed by an aerosol generator is proposed. This kind of fabric is capable of withstanding multiple usages after pre-washing and rinsing. The lowest alcohols—methanol, ethanol and isopropanol—are proposed as optimal solvents. It was shown that the phosphorylated cotton cellulose fabric impregnated with this solution generates chlorine dioxide during the first 25–35 min. Neither humidity nor expedites improve the process of releasing the chlorine dioxide, but high moisture content in the air causes the complete absorption of ClO2 by microdrops and its removal from the gas environment. A promising technique for removing the excess ClO2 by the means of UV treatment is proposed: after 15 min of treating ClO2 in the gas phase, it disappears entirely. These materials could be used as disinfectants in different industries, such as food and industrial manufacturing. [ABSTRACT FROM AUTHOR]

This study experimentally investigated the evaporation and wetting transition behavior of fakir droplets on five different microstructured surfaces. Diamond-like carbon was introduced as the substrate, and the influence of varying the width, height, and pitch of the micropillars was assessed. The experimental results showed that the interfacial properties of the surfaces change the evaporation behavior and the starting point of the wetting transition. An important result of this study is the demonstration of a slippery superhydrophobic surface with low depinning force that suppresses the transition from the Cassie–Baxter state to the Wenzel state for microdroplets less than 0.37 mm in diameter, without employing large pillar height or multiscale roughness. By selecting an appropriate pillar pitch and employing tapered micropillars with small pillar widths, the solid–liquid contact at the three-phase contact line was reduced and low depinning forces were obtained. The underlying mechanism by which slippery superhydrophobic surfaces suppress wetting transitions is also discussed. The accuracy of the theoretical models for predicting the critical transition parameters was assessed, and a numerical model was developed in the surface evolver to compute the penetration of the droplet bottom meniscus within the micropillars. [ABSTRACT FROM AUTHOR]

Due to their important roles in medicine and asymmetric metal catalysis, the formation of Betti bases has attracted wide interest in organic chemical community. Traditional multicomponent reaction methods for synthesizing Betti bases normally require long reaction times under harsh conditions (high temperature, microwave or ultrasonic irradiation, etc.) in the presence of various catalysts. In this study, we developed a mild, highly efficient and environmentally friendly method to synthesize Betti bases without the use of any catalysts in microdroplets. The Betti reaction was accelerated by 6.53×103 in microdroplets by comparing the measured rate constant in bulk. Fifteen Betti bases were synthesized by the microdroplet method using a variety of aldehydes, naphthols and amines with 68–98 % yields at a scaled‐up amount of 1.9 g h−1. Overall it is an attractive alternative to classic organic synthesis for the construction of Betti bases and derivatives. [ABSTRACT FROM AUTHOR]

At the moment, manipulation of liquid microdroplets is required in various microfluidic and lab-on-a-chip devices, as well as advanced sensors. The platforms used for these purposes should provide the possibility of controlled selective movement and coalescence of droplets, and the manipulation speed should be sufficiently high (more than 10 mm/s). In addition, to facilitate their practical application, such platforms should have a simple planar geometry and low manufacturing cost. We report here a new method for microdroplet manipulation based on the use of non-uniform electrostatic fields. Our platform uses an electrode array embedded in a dielectric planar superhydrophobic substrate (50 × 50 mm). When a voltage is applied to a certain sequence of electrodes, a non-uniform electrostatic field is produced, which acts to attract a droplet on the substrate to the electrodes. This achieves a stepwise movement of the droplet. We realized non-contact, selective and high speed (up to 80 mm/s) movement of the individual droplets along specified trajectories (like a chess game) and their selective coalescence. It allowed us to demonstrate several controllable chemical reactions including an analytical one. In our opinion, this approach has a huge potential for chemical technology applications, especially in advanced sensors. [ABSTRACT FROM AUTHOR]

Electrospray ionization (ESI) is among the commonly used atmospheric pressure ionization techniques in mass spectrometry (MS). One of the drawbacks of ESI is the formation of divergent plumes composed of polydisperse microdroplets, which lead to low transmission efficiency. Here, we propose a new method to potentially improve the transmission efficiency of ESI, which does not require additional electrical components and complex interface modification. A dielectric plate—made of ceramic—was used in place of a regular metallic sampling cone. Due to the charge accumulation on the dielectric surface, the dielectric layer around the MS orifice distorts the electric field, focusing the charged electrospray cloud towards the MS inlet. The concept was first verified using charge measurement on the dielectric material surface and computational simulation; then, online experiments were carried out to demonstrate the potential of this method in MS applications. In the online experiment, signal enhancements were observed for dielectric plates with different geometries, distances of the electrospray needle axis from the MS inlet, and various compounds. For example, in the case of acetaminophen (15 μM), the signal enhancement was up to 1.82 times (plate B) using the default distance of the electrospray needle axis from the MS inlet (d = 1.5 mm) and 12.18 times (plate C) using a longer distance (d = 7 mm).

Using devices with microfluidic channels can allow for precise control over liquids flowing through them. Merging flows of immiscible liquids can create emulsions with highly monodispersed microdroplets within a carrier liquid, which are ideal for miniaturised reaction vessels which can be generated with a high throughput of tens of thousands of droplets per second. Control of the size and composition of these droplets is generally performed by controlling the pumping system pushing the liquids into the device; however, this is an indirect manipulation and inadequate if absolute precision is required in the size or composition of the droplets. In this work, we extend the previous development of image-based closed-loop feedback control over microdroplet generation to allow for the control of not only the size of droplets but also the composition by merging two aqueous flows. The feedback allows direct control over the desired parameters of volume and ratio of the two components over a wide range of ratios and outperforms current techniques in terms of monodispersity in volume and composition. This technique is ideal for situations where precise control over droplets is critical, or where a library of droplets of different concentrations but the same volume is required.

The article discusses a study on the applications of quantum computing in chemistry, conducted by various researchers and companies such as Quantinuum and PASQAL. It mentions that quantum computers are increasingly being utilized to tackle complex chemical problems, offering the potential to revolutionize drug discovery and accelerate advancements in chemistry, with expectations high for future breakthroughs as quantum computing capabilities continue to improve.

Major advances in molecular detection are being driven by goals associated with the development of methods that are amenable to miniaturization and automation, and that have high sensitivity and low interference. The new detection methods are confronted by many interfacial issues, which when properly addressed can lead to improved performance. One interfacial property, special wettability, can facilitate precise delivery and local enrichment of molecules to sensing elements. This review summarizes applications of unique features of special wettability in molecular detection including (1) chemical and electrochemical reactions in anchored microdroplets on superwetting surfaces, (2) enrichment of analytes and active materials at low contact areas between droplets and superwetting surfaces, (3) complete opposite affinities of superwetting surfaces toward nonpolar/polar solutes and oil/water phases, and (4) directional droplet transportation on asymmetric superwetting surfaces. The challenges and opportunities that exist in design and applications of special wettability in interfacial delivery and enrichment for detection of a few molecules are also discussed. [ABSTRACT FROM AUTHOR]

Catastrophically mechanical failure of soft self-healing materials is unavoidable due to their inherently poor resistance to crack propagation. Here, with a model system, i.e., soft self-healing polyurea, we present a biomimetic strategy of surpassing trade-off between soft self-healing and high fracture toughness, enabling the conversion of soft and weak into soft yet tough self-healing material. Such an achievement is inspired by vascular smooth muscles, where core-shell structured Galinstan micro-droplets are introduced through molecularly interfacial metal-coordinated assembly, resulting in an increased crack-resistant strain and fracture toughness of 12.2 and 34.9 times without sacrificing softness. The obtained fracture toughness is up to 111.16 ± 8.76 kJ/m2, even higher than that of Al and Zn alloys. Moreover, the resultant composite delivers fast self-healing kinetics (1 min) upon local near-infrared irradiation, and possesses ultra-high dielectric constants (~14.57), thus being able to be fabricated into sensitive and self-healing capacitive strain-sensors tolerant towards cracks potentially evolved in service. Catastrophically mechanical failure, of soft self-healing materials often stems from its poor resistance to crack, propagation. Here, the authors present a strategy of surpassing trade-off, between soft self-healing and high fracture toughness, enabling the, conversion of soft and weak into soft yet tough self-healing materials. [ABSTRACT FROM AUTHOR]

Real-time image-based sorting of target cells in a precisely indexed manner is desirable for sequencing or cultivating individual human or microbial cells directly from clinical or environmental samples; however, the versatility of existing methods is limited as they are usually not broadly applicable to all cell sizes. Here, an optical tweezer-assisted pool-screening and single-cell isolation (OPSI) system is established for precise, indexed isolation of individual bacterial, yeast or human-cancer cells. A controllable static flow field that acts as a cell pool is achieved in a microfluidics chip, to enable precise and ready screening of cells of 1 to 40 μm in size by bright-field, fluorescence, or Raman imaging. The target cell is then captured by a 1064 nm optical tweezer and deposited as one-cell-harboring nanoliter microdroplets in a one-cell-one-tube manner. For bacterial, yeast and human cells, OPSI achieves a >99.7% target-cell sorting purity and a 10-fold elevated speed of 10–20 cells per min. Moreover, OPSI-based one-cell RNA-seq of human cancer cells yields high quality and reproducible single-cell transcriptome profiles. The versatility, facileness, flexibility, modularized design, and low cost of OPSI suggest its broad applications for image-based sorting of target cells. [ABSTRACT FROM AUTHOR]

In the context of personalized medicine, the analysis of single cells is key in order to understand the origin and evolution of cancer to provide an accurate prognosis. Microfluidics and microdroplets are increasingly used for the handling and understanding of the behavior of single cells, as they offer the perfect isolated environment. However, due to the small volumes handled, it is necessary to couple this technology with an ultrasensitive detection technique. Herein, surface‐enhanced Raman scattering (SERS) spectroscopy and droplet microfluidics are combined toward the multiplex phenotypic analysis of single cancer cells. For this, cancer cells are labeled with different SERS tags that recognize membrane proteins and encapsulated individually in microdroplets. Afterward, single cells within microdroplets are imaged by SERS spectroscopy. To the best of the authors' knowledge, this is the first time that a multiplex phenotypic SERS analysis of single cells in microdroplets is shown. This integrated optofluidic platform paves the way toward the multiplex and automated characterization of cell populations in cancer patients. [ABSTRACT FROM AUTHOR]

Droplet microfluidics has revolutionized the field of single‐cell analysis. Production of micro‐droplets at high throughput allows for rapid isolation of single cells within micro‐compartments, which are then subjected to different analytical processes. However, certain operations, such as physical separation from droplets, remain difficult to implement at high throughput and single‐cell level but would be highly valuable to currently expanding multiomics techniques, where several biomolecular modalities are involved. This work presents a method based on microfabricated NiFe structures, the magnetic microtweezers, to trap and extract magnetic particles from a continuous stream of sub‐nanoliter droplets, and enable physical separation from single cell‐based droplets. Using a physical model, simulations, and experiments, a comprehensive description of the complex particle extraction process is provided. After optimization, the magnetic microtweezers provided unprecedented particle extraction performance, allowing extraction of high loads (10‐20 ng) of magnetic particles from 500 pL droplets, with a capture rate close to 100% at 20 Hz. To evaluate the applicability to single‐cell analysis, mRNA extraction is performed. It demonstrated around 72% specific recovery of mRNA from droplets containing purified nucleic acids, and 43% from single cells. Overall, this approach enables efficient physical separation that is compatible with existing high‐throughput droplet‐based single‐cell workflows. [ABSTRACT FROM AUTHOR]

Flow‐focusing microfluidic devices have been widely used for generating compound droplets. However, most devices are disposable and difficult to recycle, and key geometrical parameters cannot be changed after fabrication. This paper presents a reusable and adjustable microfluidic device composed of glass capillaries and polydimethylsiloxane. The main components of the device can be freely assembled and disassembled, illustrating the reproducibility and scalability of the device. The channel wall is composed of glass or polydimethylsiloxane, allowing for different wetting conditions. The experiments show that combining capillaries with straight, stepped, and tapered shapes can change the flow field at the channel junction. Thus, compound microdroplets with core‐shell, Janus, and ternary morphologies can be generated for the same combination of liquids. The droplets are used to prepare microparticles of different shapes. With the wide selection of off‐the‐shelf capillaries, this microfluidic configuration can be used for rapid prototyping, and mass production of the devices can allow for high‐throughput generation of droplets or particles in parallel. [ABSTRACT FROM AUTHOR]

Plasma dust formations with liquid particles (microdroplets) are studied. Methods used for the formation of liquid microdroplets in a vacuum are analyzed in the study, and a laboratory bench for studying liquid plasma dust formations is constructed. The phenomenon is examined and photographed. [ABSTRACT FROM AUTHOR]

Laser-assisted bioprinting of microbial cells by hydrogel microdroplets is a rapidly developing and promising field that can contribute to solving a number of issues in microbiology and biotechnology. To date, most research on the use of laser bioprinting for microorganism manipulation and sorting has focused on prokaryotes; the bioprinting of eukaryotic microorganisms is much less understood. The use of hydrogel allows solving two fundamental problems: creating comfortable environments for living microorganisms and imparting the necessary rheological properties of the gel for the stable transfer of microdroplets of a preset size. Two main problems were solved in this article. First, the parameters of the hydrogel based on hyaluronic acid and laser fluence to ensure stable transfer of single drops are selected. Second, possible differences in the bioprinting by hyaluronic acid hydrogel microdroplets with yeasts of various taxonomy (Ascomycota vs Basidiomycota), which form and do not form polysaccharide capsules and evaluated. We have performed laser induced forward transfer of 8 yeast species (Goffeauzyma gilvescens, Lipomyces lipofer, Lipomyces starkey, Pichia manshurica, Saitozyma podzolica, Schwanniomyces occidentalis var. occidentalis, Sterigmatosporidium polymorphum, Vanrija humicola) and assessed its viability based on colony formation on the nutrient medium. It is shown that after laser-induced transfer in hydrogel microdroplets the mean viability rate was 77% with some strains showing relatively high viability rates exceeding 90%. Effect of capsules presence on colony formation after laser bioprinting was not revealed. Differences in laser transfer of the yeast of various phyla were found—basidiomycetes formed a greater number of colonies than ascomycetes. The causes and mechanisms of these effects require detailed studies. The data obtained contributes to the knowledge about the bioprinting of eukaryotic microorganisms and can be useful in the studies of single microbial cells and inter-organism interactions. [ABSTRACT FROM AUTHOR]

Micro-droplets are widely used in the fields of chemical and biological research, such as drug delivery, material synthesis, point-of-care diagnostics, and digital PCR. Droplet-based microfluidics has many advantages, such as small reagent consumption, fast reaction time, and independent control of each droplet. Therefore, various micro-droplet generation methods have been proposed, including T-junction breakup, capillary flow-focusing, planar flow-focusing, step emulsification, and high aspect (height-to-width) ratio confinement. In this study, we propose a microfluidic device for generating monodisperse micro-droplets, the microfluidic channel of which has an asymmetric cross-sectional shape and high hypotenuse-to-width ratio (HTWR). It was fabricated using basic MEMS processes, such as photolithography, anisotropic wet etching of Si, and polydimethylsiloxane (PDMS) molding. Due to the geometric similarity of a Si channel and a PDMS mold, both of which were created through the anisotropic etching process of a single crystal Si, the microfluidic channel with the asymmetric cross-sectional shape and high HTWR was easily realized. The effects of HTWR of channels on the size and uniformity of generated micro-droplets were investigated. The monodisperse micro-droplets were generated as the HTWR of the asymmetric channel was over 3.5. In addition, it was found that the flow direction of the oil solution (continuous phase) affected the size of micro-droplets due to the asymmetric channel structures. Two kinds of monodisperse droplets with different sizes were successfully generated for a wider range of flow rates using the asymmetric channel structure in the developed microfluidic device. [ABSTRACT FROM AUTHOR]

Core/shell microdroplets formation with uniform size is investigated numerically in the co-flow microchannel. The interface and volume fraction contour between three immiscible fluids are captured using a ternary phase-field model. Previous research has shown that the effective parameters of microdroplet size are the physical properties and velocity of the three phases. By adjusting these variables, five main flow patterns are observed in numerical simulations. A core/shell dripping/slug regime is observed when the inertia of the continuous phase breaks the flow of the core and shell phases and makes a droplet. In the slug regime, the continuous phase has less inertia, and the droplets that form are surrounded by the channel walls, while in the dripping regime, the shell phase fluid is surrounded by the continuous phase. An increase in continuous-fluid or shell-fluid flow rate leads to dripping to a jetting transition. When three immiscible liquids flow continuously and parallel to one another without dispersing, this is known as laminar flow. In the tubing regime, the core phase flows continuously in the channel's central region, the shell phase flows in the annulus formed by the core phase's central region, and the continuous phase flows between the shell phase fluid and channel walls. In order to discriminate between the aforementioned flow patterns using Weber and Capillary numbers and establish regime transition criteria based on these two dimensionless variables, a flow regime map is provided. Finally, a correlation for shell thickness using shell-to-core phase velocity ratio and conducting 51 CFD simulations was proposed. [ABSTRACT FROM AUTHOR]

Controllable mass production of monodisperse droplets plays a key role in numerous fields ranging from scientific research to industrial application. Microfluidic ladder networks show great potential in mass production of monodisperse droplets, but their design with uniform microflow distribution remains challenging due to the lack of a rational design strategy. Here an effective design strategy based on backstepping microflow analysis (BMA) is proposed for the rational development of microfluidic ladder networks for mass production of controllable monodisperse microdroplets. The performance of our BMA rule for rational microfluidic ladder network design is demonstrated by using an existing analogism-derived rule that is widely used for the design of microfluidic ladder networks as the control group. The microfluidic ladder network designed by the BMA rule shows a more uniform flow distribution in each branch microchannel than that designed by the existing rule, as confirmed by single-phase flow simulation. Meanwhile, the microfluidic ladder network designed by the BMA rule allows mass production of droplets with higher size monodispersity in a wider window of flow rates and mass production of polymeric microspheres from such highly monodisperse droplet templates. The proposed BMA rule provides new insights into the microflow distribution behaviors in microfluidic ladder networks based on backstepping microflow analysis and provides a rational guideline for the efficient development of microfluidic ladder networks with uniform flow distribution for mass production of highly monodisperse droplets. Moreover, the BMA method provides a general analysis strategy for microfluidic networks with parallel multiple microchannels for rational scale-up. [ABSTRACT FROM AUTHOR]

This work focuses on identifying and prioritizing factors that allow control of the properties of polyelectrolyte-surfactant complexes in two-phase microfluidic confinement and provide advantages over synthesis of such complexes in macroscopic conditions. We characterize the impact of polymer and surfactant aqueous flow conditions on the formation of microscale droplets and fluid threads in the presence of an immiscible organic solvent. We perform an experimental and selected numerical analysis of fast supramolecular reactions in droplets and threads. The work offers a quantitative control over properties of polyelectrolyte-surfactant complexes produced in two-phase confinement by varying capillary numbers and the ratio of aqueous and organic flowrates. We propose a combined thread-droplet mode to synthesize polyelectrolyte-surfactant complexes. This mode allows the production of complexes in a broader size range of R ≈ 70–200 nm, as compared with synthesis in macroscopic conditions and the respective sizes R ≈ 100–120 nm. Due to a minimized impact of undesirable post-chip reactions and ordered microfluidic confinement conditions, the dispersity of microfluidic aggregates (PDI = 0.2–0.25) is lower than that of their analogs synthesized in bulk (PDI = 0.3–0.4). The proposed approach can be used for tailored synthesis of target drug delivery polyelectrolyte-surfactant systems in lab-on-chip devices for biomedical applications. [ABSTRACT FROM AUTHOR]

The sulfur fluoride exchange (SuFEx) reaction is significant in drug discovery, materials science, and chemical biology. Conventionally, it involves installation of SO2F followed by fluoride exchange by a catalyst. We report catalyst‐free Aza‐Michael addition to install SO2F and then SuFEx reaction with amines, both occurring in concert, in microdroplets under ambient conditions. The microdroplet reaction is accelerated by a factor of ∼104 relative to the corresponding bulk reaction. We suggest that the superacidic microdroplet surface assists SuFEx reaction by protonating fluorine to create a good leaving group. The reaction scope was established by performing individual reactions in microdroplets of 18 amines in four solvents and confirmed using high‐throughput desorption electrospray ionization experiments. The study demonstrates the value of microdroplet‐assisted accelerated reactions in combination with high‐throughput experimentation for characterization of reaction scope. [ABSTRACT FROM AUTHOR]