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Highly scattering samples, such as polymer droplets or solid-state powders, are difficult to study via coherent two-dimensional infrared (2D IR) spectroscopy. Previously, researchers have employed (quasi-) phase cycling, local-oscillator chopping, and polarization control to reduce scattering, but the latter method poses a limit on polarization-dependent measurements. Here, we present a method for Scattering Elimination Immune from Detector Artifacts (SEIFDA) in pump–probe 2D IR experiments. Our method extends the negative probe delay method of removing scattering from pump–probe spectroscopy to 2D experiments. SEIFDA works well for all polarizations when combined with the optimized noise reduction scheme to remove additive and multiplicative noise. We demonstrate that our method can be employed with any polarization scheme and reliably lowers the scattering at parallel polarization to comparable levels to the conventional 8-frame phase cycling with probe chopping (8FPCPC) at perpendicular polarization. Our system can acquire artifact free spectra in parallel polarization when the signal intensity is as little as 5% of the intensity of the interference between the pump pulses scattered into the detector. It reduces the time required to characterize the scattering term by at least 50% over 8FPCPC. Through detailed analysis of detector nonlinearity, we show that the performance of 8FPCPC can be improved by incorporating nonlinear correction factors, but it is still worse than that of SEIFDA. Application of SEIFDA to study the encapsulation of Nile red in polymer droplets demonstrates that this method will be very useful for probing highly scattering systems.

Supplemental Digital Content is Available in the Text.

Supplemental Digital Content is Available in the Text.

Polymorphism is an important concept in crystallization and has been widely studied for many systems, including calcium carbonate and zeolite materials. Metal–organic frameworks (MOFs) are crystalline materials that exhibit polymorphism. MOF polymorphism has been widely studied from the perspective of which synthetic factors, such as the ligand to metal ratio, can be used to control the final polymorph. However, limited studies on the nucleation mechanism of multipolymorph MOFs have been performed. Here we study the formation of a model zeolitic imidazole framework-8 and the mechanism that drives the formation of the two most commonly observed polymorphs, sodalite and diamondoid. To understand the mechanism and factors that affect polymorph formation, we performed time-resolved in situ wide-field X-ray scattering, electrospray ionization mass spectrometry, and time-resolved cryogenic transmission electron microscopy. The collective data reveal a clear correlation between the size of the prenucleation clusters and the final polymorph. By gaining a deeper understanding of the mechanisms governing polymorph control in MOF systems, we can improve the design of synthetic conditions, allowing the tailoring of crystal properties.

Electrochemical liquid electron microscopy has revolutionized our understanding of nanomaterial dynamics by allowing for direct observation of their electrochemical production. This technique, primarily applied to inorganic materials, is now being used to explore the self-assembly dynamics of active molecular materials. Our study examines these dynamics across various scales, from the nanoscale behavior of individual fibers to the micrometer-scale hierarchical evolution of fiber clusters. To isolate the influences of the electron beam and electrical potential on material behavior, we conducted thorough beam–sample interaction analyses. Our findings reveal that the dynamics of these active materials at the nanoscale are shaped by their proximity to the electrode and the applied electrical current. By integrating electron microscopy observations with reaction–diffusion simulations, we uncover that local structures and their formation history play a crucial role in determining assembly rates. This suggests that the emergence of nonequilibrium structures can locally accelerate further structural development, offering insights into the behavior of active materials under electrochemical conditions.

The importance and prevalence of energy-fueled active materials in living systems have inspired the design of synthetic active materials using various fuels. However, several major limitations of current designs remain to be addressed, such as the accumulation of chemical wastes during the process, unsustainable active behavior, and the lack of precise spatiotemporal control. Here, we demonstrate a fully electrically fueled (e-fueled) active self-assembly material that can overcome the aforementioned limitations. Using an electrochemical setup with dual electrocatalysts, the anodic oxidation of one electrocatalyst (ferrocyanide, [Fe(CN)6]4–) creates a positive fuel to activate the self-assembly, while simultaneously, the cathodic reduction of the other electrocatalyst (methyl viologen, [MV]2+) generates a negative fuel triggering fiber disassembly. Due to the fully catalytic nature for the reaction networks, this fully e-fueled active material system does not generate any chemical waste, can sustain active behavior for an extended period when the electrical potential is maintained, and provides spatiotemporal control.

Biomass burning organic aerosol (BBOA) is one of the largest sources of organics in the atmosphere. Mineral dust and biomass burning smoke frequently co-exist in the same atmospheric environment. Common biomass burning compounds, such as dihydroxybenzenes and their derivatives, are known to produce light-absorbing, water-insoluble polymeric particles upon reaction with soluble Fe(iii) under conditions characteristic of aerosol liquid water. However, such reactions have not been tested in realistic mixtures of BBOA compounds. In this study, model organic aerosol (OA), meant to replicate BBOA from smoldering fires, was generated through the pyrolysis of Canary Island pine needles in a tube furnace at 300, 400, 500, 600, 700, and 800 °C in nitrogen gas, and the water-soluble fractions were reacted with iron chloride under dark, acidic conditions. We utilized spectrophotometry to monitor the reaction progress. For OA samples produced at lower temperatures (300 and 400 °C), particles (P300 and P400) formed in solution, were syringe filtered, and extracted in organic solvents. Analysis was conducted with ultrahigh pressure liquid chromatography coupled to a photodiode array spectrophotometer and a high-resolution mass spectrometer (UHPLC-PDA-HRMS). For OA samples formed at higher pyrolysis temperatures (500–800 °C), water-insoluble, black particles (P500–800) formed in solution. In contrast to P300 and P400, P500–800 were not soluble in common solvents. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM) were used to image P600 and determine bulk elemental composition. Electron microscopy revealed that P600 had fractal morphology, reminiscent of soot particles, and contained no detectable iron. These results suggest that light-absorbing aerosol particles can be produced from Fe(iii)-catalyzed reactions in aging BBOA plumes produced from smoldering combustion in the absence of any photochemistry. This result has important implications for understanding the direct and indirect effects of aged BBOA on climate.

Chlorhexidine skin antisepsis is frequently recommended for most surgical procedures; however, it is unclear if these recommendations should apply to surgery involving traumatic contaminated wounds where povidone-iodine has previously been preferred. We aimed to compare the effect of aqueous 10% povidone-iodine versus aqueous 4% chlorhexidine gluconate on the risk of surgical site infection in patients who required surgery for an open fracture.

Metal–organic frameworks (MOFs) are a class of porous nanomaterials that have been extensively studied as enzyme immobilization substrates. During in situ immobilization, MOF nucleation is driven by biomolecules with low isoelectric points. Investigation of how biomolecules control MOF self-assembly mechanisms on the molecular level is key to designing nanomaterials with desired physical and chemical properties. Here, we demonstrate how molecular modifications of bovine serum albumin (BSA) with fluorescein isothiocyanate (FITC) can affect MOF crystal size, morphology, and encapsulation efficiency. Final crystal properties are characterized using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), fluorescent microscopy, and fluorescence spectroscopy. To probe MOF self-assembly, in situ experiments were performed using cryogenic transmission electron microscopy (cryo-TEM) and X-ray diffraction (XRD). Biophysical characterization of BSA and FITC-BSA was performed using ζ potential, mass spectrometry, circular dichroism studies, fluorescence spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The combined data reveal that protein folding and stability within amorphous precursors are contributing factors in the rate, extent, and mechanism of crystallization. Thus, our results suggest molecular modifications as promising methods for fine-tuning protein@MOFs’ nucleation and growth.

Fuel-driven dissipative self-assemblies play essential roles in living systems, contributing both to their complex, dynamic structures and emergent functions. Several dissipative supramolecular materials have been created using chemicals or light as fuel. However, electrical energy, one of the most common energy sources, has remained unexplored for such purposes. Here, we demonstrate a new platform for creating active supramolecular materials using electrically fueled dissipative self-assembly. Through an electrochemical redox reaction network, a transient and highly active supramolecular assembly is achieved with rapid kinetics, directionality, and precise spatiotemporal control. As electronic signals are the default information carriers in modern technology, the described approach offers a potential opportunity to integrate active materials into electronic devices for bioelectronic applications.

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Materials are needed to increase the stability and half-life of therapeutic proteins during delivery. These materials should be biocompatible and biodegradable. Here, we demonstrate that enzymes and immunoproteins can be encapsulated inside cyclodextrin based metal–organic frameworks using potassium as the metal node. The release profile can be controlled with the solubility of the cyclodextrin linker. The activity of the proteins after release is determined using catalytic and in vitroassays. The results show that cyclodextrin metal–organic framework-based protein biocomposites are a promising class of materials to deliver therapeutic proteins.

Electron microscopy (EM) of materials undergoing chemical reactions provides knowledge of the underlying mechanisms. However, the mechanisms are often complex and cannot be fully resolved using a single method. Here, we present a distributed electron microscopy method for studying complex reactions. The method combines information from multiple stages of the reaction and from multiple EM methods, including liquid phase EM (LP-EM), cryogenic EM (cryo-EM), and cryo-electron tomography (cryo-ET). We demonstrate this method by studying the desilication mechanism of zeolite crystals. Collectively, our data reveal that the reaction proceeds viaa two-step anisotropic etching process and that the defects in curved surfaces and between the subunits in the crystal control the desilication kinetics by directing mass transport.

Liquid phase electron microscopy (LP-EM) is a rapidly developing method for imaging chemical processes in solution. A key strength of this method is that the high energy electrons can be used as both an energy and illumination source. This enables simultaneous control of the chemistry with nanoscale structural characterization. As electron beams are widely used in the manufacturing of polymeric materials, we believe that the knowledge obtained from LP-EM can directly guide industrial electron beam technologies, enabling the design, optimization, and manufacturing of nanostructured polymeric materials. In this Perspective, we outline the advances made in electron beam synthesis of polymeric materials and discuss the challenges and opportunities for utilizing LP-EM in conjunction with electron beam manufacturing technologies.

Periodic nano- or microscale structures are used to control light, energy and mass transportation. Colloidal organization is the most versatile method used to control nano- and microscale order, and employs either the enthalpy-driven self-assembly of particles at a low concentration or the entropy-driven packing of particles at a high concentration. Nonetheless, it cannot yet provide the spontaneous three-dimensional organization of multicomponent particles at a high concentration. Here we combined these two concepts into a single strategy to achieve hierarchical multicomponent materials. We tuned the electrostatic attraction between polymer and silica nanoparticles to create dynamic supracolloids whose components, on drying, reorganize by entropy into three-dimensional structured materials. Cryogenic electron tomography reveals the kinetic pathways, whereas Monte Carlo simulations combined with a kinetic model provide design rules to form the supracolloids and control the kinetic pathways. This approach may be useful to fabricate hierarchical hybrid materials for distinct technological applications.

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Liquid–liquid phase separation of macromolecules is an important process in many biological and synthetic systems. The process results in the formation of coacervates that act as membraneless compartments for storage and concentrated polymer precursors to solid phase materials. Here, we present a general strategy to form coacervates from nonionic block copolymers by controlling the molecular structure and solvent composition. The mechanism of coacervation is studied using a combination of optical microscopy and cryogenic and liquid phase electron microscopy, revealing a coalescence-driven growth process. Knowledge of the mechanism enables the design of experiments where morphological information is encoded into the coacervate phase and developed into the solid phase. The results show that self-assembled materials can be formed with multiple morphologies from the nanoscale up to the macroscale by controlling the kinetics of the coacervation and self-assembly process.

Protein–metal–organic frameworks (p-MOFs) are a prototypical example of how synthetic biological hybrid systems can be used to develop next-generation materials. Controlling p-MOF formation enables the design of hybrid materials with enhanced biological activity and high stability. However, such control is yet to be fully realized due to an insufficient understanding of the governing nucleation and growth mechanisms in p-MOF systems. The structural evolution of p-MOFs was probed by cryo-transmission electron microscopy, revealing nonclassical pathways via dissolution–recrystallization of highly hydrated amorphous particles and solid-state transformation of a protein-rich amorphous phase. On the basis of these data, we propose a general description of p-MOF crystallization which is best characterized by particle aggregation and colloidal theory for future synthetic strategies.

A specialized facility was constructed to investigate the Joule-Thomson (JT) effect during fluid expansion over a valve. The flow loop facility consists of 1.5 m long, 1 in. outer diameter test sections located up- and downstream of an expansion valve, supported by process equipment to control and monitor local pressures and temperatures. The loop features a 1 m removable section after the expansion valve, enabling postexperiment visual inspection of the pipe. Pressure and temperature sensors are instrumented along the 3 m test section, giving spatially resolved information on the dynamic response of a fluid experiencing JT expansion. The expansion and cooling of dry and wet nitrogen, and dry methane were studied with the facility through experiments conducted in pressure-driven batch mode. A dynamic model incorporating thermodynamic predictions of the fluid’s JT coefficient was used to calculate the temperature drop across the valve for a range of experiments. The dynamic model calculations for dry gas systems were consistent to within 10% during the period of experiments where the assumption of isenthalpic expansion is reasonable. However, significant deviations were observed for wet gas systems even though the JT coefficients of both vapor and liquid phases in the mixture were considered. To build a more accurate dynamic model for systems comprising both a gas and aqueous phase, further JT expansion measurements are needed across a variety of water loadings. The facility reported here is ideal for studying the dynamic response of JT cooling for both subsea applications, and in the relief systems of process facilities.

Metadiaphyseal proximal radius fractures blur the distinction between the radial neck and radial shaft fractures. Operative management presents unique technical challenges both in terms of surgical approach and fixation method. We discuss relevant anatomy, safe surgical approach, and options and techniques for fracture fixation. We describe 6 patients who achieved satisfactory functional outcomes, even in cases of severe bone loss secondary to ballistic trauma. An extensile dorsal approach with exposure of the posterior interosseous nerve is recommended when normal soft tissue intervals have not already been extensively disrupted. Robust fixation can be achieved by contouring and repurposing a variety of plates such as a variety of mini fragment plates (2.4 mm T or Y-plates), flexible nails, or even distal radius plates.