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Thescalable synthesis of high-temperature H-2-sieving membranesfor energy-efficient carbon capture can potentiallyenable the implementation of precombustion carbon capture at a rapidpace., Synthesis of H-2-sieving membranes for high-temperatureapplications is highly desired for improving the energy efficiencyof H-2 production from steam reforming and developing alow-cost solution for precombustion carbon capture. Zeolite-basedmembranes are ideal for this because they possess excellent hydrothermalstability. However, current methods to synthesize H-2-sievingzeolite membranes rely on hydrothermal synthesis on expensive ceramicsupports followed by postsynthetic functionalization to shrink theeffective pore size. The scalable synthesis approach on a low-costpolymeric support implementable at room temperature is highly desiredto advance applications based on H-2-sieving membranes.Herein, we report the room-temperature fabrication of H-2-sieving zeolitic membranes by simply assembling sodalite precursor,i.e., RUB-15 nanosheets, on a porous polybenzimidazole support. Thepresence of adsorbed surfactants on the nanosheets led to an entropicallydriven ordering of the nanosheets witnessed by a sharp (200) d-spacing peak by X-ray diffraction. The intersheet gapwas successfully eliminated by the ion exchange of cationic surfactantsby a diluted acetic acid solution. The resulting zeolitic films showattractive H-2/CO2 and H-2/CH4 separation performances at elevated temperatures. The fabricationof H-2-sieving zeolitic membranes without resorting to hydrothermalsynthesis or high-temperature activation is expected to push the effortsto scale up zeolite membranes for application in gas separation andmembrane reactors.

Novel and improved biocatalysts are increasingly sourced from libraries via experimental screening. The success of such campaigns is crucially dependent on the number of candidates tested. Water-in-oil emulsion droplets can replace the classical test tube, to provide in vitro compartments as an alternative screening format, containing genotype and phenotype and enabling a readout of function. The scale-down to micrometer droplet diameters and picoliter volumes brings about a >107-fold volume reduction compared to 96-well-plate screening. Droplets made in automated microfluidic devices can be integrated into modular workflows to set up multistep screening protocols involving various detection modes to sort >107 variants a day with kHz frequencies. The repertoire of assays available for droplet screening covers all seven enzyme commission (EC) number classes, setting the stage for widespread use of droplet microfluidics in everyday biochemical experiments. We review the practicalities of adapting droplet screening for enzyme discovery and for detailed kinetic characterization. These new ways of working will not just accelerate discovery experiments currently limited by screening capacity but profoundly change the paradigms we can probe. By interfacing the results of ultrahigh-throughput droplet screening with next-generation sequencing and deep learning, strategies for directed evolution can be implemented, examined, and evaluated.

In the present work, we developed an effective antimicrobial surface film based on sustainable microfibrillated cellulose. The resulting porous cellulose thin film is barely noticeable to human eyes due to its submicrometer thickness, of which the surface coverage, porosity, and microstructure can be modulated by the formulations and the coating process. Using goniometers and a quartz crystal microbalance, we observed a threefold reduction in water contact angles and accelerated water evaporation kinetics on the cellulose film (more than 50% faster than that on a flat glass surface). The porous cellulose film exhibits a rapid inactivation effect against SARS-CoV-2 in 5 min, following deposition of virus-loaded droplets, and an exceptional ability to reduce contact transfer of liquid, e.g., respiratory droplets, to surfaces such as an artificial skin by 90% less than that from a planar glass substrate. It also shows excellent antimicrobial performance in inhibiting the growth of both Gram-negative and Gram-positive bacteria (Escherichia coli and Staphylococcus epidermidis) due to the intrinsic porosity and hydrophilicity. Additionally, the cellulose film shows nearly 100% resistance to scraping in dry conditions due to its strong affinity to the supporting substrate but with good removability once wetted with water, suggesting its practical suitability for daily use. Importantly, the coating can be formed on solid substrates readily by spraying, which requires solely a simple formulation of a plant-based cellulose material with no chemical additives, rendering it a scalable, affordable, and green solution as antimicrobial surface coating. Implementing such cellulose films could thus play a significant role in controlling future pan- and epidemics, particularly during the initial phase when suitable medical intervention needs to be developed and deployed.

International audience; Environmental pollution monitoring represents a major challenge due to the growing presence of a large and diverse number of potential contaminants. In complement to target analysis, nontarget analysis, via liquid chromatography (LC) coupled to high-resolution mass spectrometry (HRMS), is increasingly used to provide a more comprehensive characterization of pollution. The challenge associated with this type of analysis is particularly related to the data treatment for substance identification. One of the main limitations is that all data must be manually reviewed, which is tedious and time-consuming. Machine learning algorithms aim to reproduce human behavior, and their capabilities were therefore evaluated to automatically identify substances in suspect screening approaches. After selecting the relevant features produced from LC/HRMS, seven different machine learning models were evaluated for each of the three different databases, which resulted in the selection of logistic regression (LR) and random forest (RF)-based algorithms. An interface was built to rank the identified substances and to assess the performance of the developed models. The LR model provided the best results when retention times were available. The developed LR and RF models were determined complementarily, particularly when no retention times were available. However, limitations were noticed when using a database containing different HRMS technologies.

An asymmetric catalytic approach for the construction of C3-multifunctionalization α-hydroxy-β-amino pyridines has been reported. The products can be accessed by the modulation of two chiral catalysts independently in high yield and with good enantioselectivity. The method features mild reaction conditions and an excellent functional group tolerance. Biological activity analysis shows that the resulting products have a selective antiosteosarcoma activity on 143B cells.

Pharmaceutical salts are ubiquitously present in the market given their benefits in optimizing the critical properties of an active pharmaceutical ingredient (API). Achieving these benefits requires careful selection and understanding of the salt form of choice. Stability is especially critical here, as salts are susceptible to disproportionation. Several studies have shown the impact of moisture on disproportionation, with more focus on external humidity (moisture coming from outside the system). This work, on the other hand, is systematically designed to study the impact of moisture generated in situ (moisture produced within the system). To that end, an in-house developed compound

A hydrophobic Schiff base catecholate vanadium complex was recently discovered to have anticancer properties superior to cisplatin and suited for intratumoral administration. This [VO(HSHED)(DTB)] complex, where HSHED is

Herein, a peculiar fluorometric as well as smartphone-assisted RGB-relied sensing assay is introduced for determining pendimethalin (PDM) herbicide contents (in parts per trillion level) based on the anthracene-incorporated pyrimidinone/thione probes (S1 to S4). These compounds offered a unique and impressive aggregation-induced emission enhancement (AIEE) behavior by aggregation in H

Fluorescent nanocarbons are well-proficient nanomaterials because of their optical properties and surface engineering. Herein

Maximizing the usable space of electrocatalysts and fine-tuning the interface geometry as well as the electronic structure to facilitate hydrogen and oxygen evolution reactions (HER and OER) have always been the focus of research. Herein, a homogeneous porous nanoparticle construction strategy was proposed, in which molybdenum nitride (Mo

The molecular mechanism behind the ice growth inhibition by antifreeze proteins (AFPs) is yet to be understood completely. Also, what physical parameters differentiate between the AFP and non-AFP are largely unknown. Thus, to get an atomistic overview of the differential antifreeze activities of different classes of AFPs, we have studied ice growth from different ice surfaces in the presence of a moderately active globular type III AFP and a hyperactive spruce budworm (sbw) AFP. Results are compared with the observations of ice growth simulations in the presence of topologically similar non-AFPs using all-atom molecular dynamics simulations. Simulation data suggest that the ice surface coverage is a critical factor in ice growth inhibition. Due to the presence of an ice binding surface (IBS), AFPs form a high affinity complex with ice, accompanied by a transition of hydration water around the IBS from clathrate-like to ice-like. Several residues around the periphery of the IBS anchor the AFP to the curved ice surface mediated by multiple strong hydrogen bonds, stabilizing the complex immensely. In the high surface coverage regime, the slow unbinding kinetics dominates over the ice growth kinetics and thus facilitates the ice growth inhibition. Due to the non-availability of a proper IBS, non-AFPs form a low-affinity complex with the growing ice surface. As a result, the non-AFPs are continuously repelled by the surface. If the concentration of AFPs is low, then the effective surface coverage is reduced significantly. In this low surface coverage regime, AFPs can also behave like impurities and are engulfed by the growing ice crystal.

We calculated the free energies for calcium, magnesium, and zinc ions binding to a zwitterionic phospholipid bilayer by using molecular dynamics simulations and the enhanced umbrella sampling technique. By decomposing the free energy into entropic and enthalpic contributions, we found that Ca

The accurate description of the structures of water and hydrated ions is important in electrochemical desalination, ion separation, and supercapacitors. In this work, we present an ab initio atomistic simulation-based study to explore the structure of water and hydrated monovalent ions (Li

The bulk viscosity, a transport coefficient in the Navier-Stokes equation, is often neglected in the continuum mechanics of Newtonian fluids. Recently, however, the role of the bulk viscosity is highlighted in the area of surface and interface-related phenomena, in systematic model up-scaling and as an important quantity for the interpretation of acoustic sensor data. The prediction of the bulk viscosity usually employs molecular dynamics and the Green-Kubo linear response theory, which is used to sample transport properties in general from molecular trajectories. Since simulations are usually carried out at specified state points in concert with the evaluation of other thermodynamic properties, the role of thermostats in molecular dynamics needs to be explored systematically. In this work, we carefully investigate the role of thermostatting schemes and numerical implementations of the Green-Kubo formalism, in particular in the canonical ensemble, using two popular water force field models. It turns out that the sampling of the bulk and shear viscosities is a delicate challenge since details of thermostatting and numerical subtleties may have an influence on the results beyond statistical uncertainties. Based on the present findings, we conclude with hints on how to construct robust sampling in the canonical ensemble for the bulk viscosity.

ConspectusThe gas-liquid interface of water is environmentally relevant due to the abundance of aqueous aerosol particles in the atmosphere. Aqueous aerosols often contain a significant fraction of organics. As aerosol particles are small, surface effects are substantial but not yet well understood. One starting point for studying the surface of aerosols is to investigate the surface of aqueous solutions. We review here studies of the surface composition of aqueous solutions using liquid-jet photoelectron spectroscopy in combination with theoretical simulations. Our focus is on model systems containing two functional groups, the carboxylic group and the amine group, which are both common in atmospheric organics. For alkanoic carboxylic acids and alkyl amines, we find that the surface propensity of such amphiphiles can be considered to be a balance between the hydrophilic interactions of the functional group and the hydrophobic interactions of the alkyl chain. For the same chain length, the neutral alkyl amine has a lower surface propensity than the neutral alkanoic carboxylic acid, whereas the surface propensity of the corresponding alkyl ammonium ion is higher than that of the alkanoic carboxylate ion. This different propensity leads to a pH-dependent surface composition which differs from the bulk, with the neutral forms having a much higher surface propensity than the charged ones. In aerosols, alkanoic carboxylic acids and alkyl amines are often found together. For such mixed systems, we find that the oppositely charged molecular ions form ion pairs at the surface. This cooperative behavior leads to a more organic-rich and hydrophobic surface than would be expected in a wide, environmentally relevant pH range. Amino acids contain a carboxylic and an amine group, and amino acids of biological origin are found in aerosols. Depending on the side group, we observe surface propensity ranging from surface-depleted to enriched by a factor of 10. Cysteine contains one more titratable group, which makes it exhibit more complex behavior, with some protonation states found only at the surface and not in the bulk. Moreover, the presence of molecular ions at the surface is seen to affect the distribution of inorganic ions. As the charge of the molecular ions changes with protonation, the effects on the inorganic ions also exhibit a pH dependence. Our results show that for these systems the surface composition differs from the bulk and changes with pH and that the results obtained for single-component solutions may be modified by ion-ion interactions in the case of mixed solutions.

Reliable water service delivery continues to be a complex global issue that is particularly challenging in rural communities. Despite billions of dollars of infrastructure interventions, sustainable water services remain out of reach for millions of people. Professionalized maintenance services have emerged as a service provision strategy to supplement the community-based rural water management approach. This study applies system dynamics modeling to assess the potential impact of scaling up professionalized maintenance services on piped water systems in Kitui County, Kenya. The study results show that over a 10 year simulation, calibrated with 21 months of empirical data and based on a range of key assumptions, delivery of professionalized maintenance services across the county may increase countywide functionality rates from 54% to over 83%, leading to a 67% increase in water production. Furthermore, the increase in preventive maintenance activities and proactive repairs can lead to less frequent major breakdowns and reduction in county government spending on major repairs by over 60%. However, current service fee income from communities accounts for 8% of the total cost of service, necessitating substantial sustained external financing or government subsidies to be financially viable at scale.

Eradication of biofilms that may harbor pathogens in water distribution systems is an elusive goal due to limited penetration of residual disinfectants. Here, we explore the use of engineered filamentous coliphage M13 for enhanced biofilm affinity and precise delivery of lytic polyvalent phages (i.e., broad-host-range phages lysing multiple host strains after infection). To promote biofilm attachment, we modified the M13 major coat protein (pVIII) by inserting a peptide sequence with high affinity for

Although fused deposition modeling (FDM) has made it possible to create reproducible three-dimensional poly(lactic acid) (PLA) scaffolds, their efficacy for tissue engineering applications is limited by their lack of osteoinductive properties and antibacterial functions. Building on the success of the FDM constructs capable of supporting bone regeneration, we report here on the development of PLA scaffolds infused with sodium alginate cross-linked with both calcium and zinc divalent cations. Zn

The design, synthesis, and characterization of a novel Ni(II) chelator

Perfluoroalkyl acids (PFAAs) are persistent environmental contaminants that sorb to air-water and solid interfaces throughout the vadose zone. These sorption processes lead to decadal leaching of PFAS from the source zones to groundwater systems. While these processes are increasingly well understood, critical gaps exist in describing the vertically variable adsorption in the presence of vadose zone heterogeneity and methods for efficiently upscaling the laboratory observations to predict field-scale PFAA transport and retardation. In this work, we build upon fundamental theories and scalable relationships to define a semi-analytical framework for synthesizing and upscaling PFAA adsorption in heterogeneous vadose zone systems. Solid-phase and air-water interfacial adsorption are quantified mechanistically for several PFAAs and then applied to a contaminated site in Northern Wisconsin. The results highlight the dominance of air-water and organic carbon solid-phase adsorption processes in the vadose zone. Strong sorption heterogeneity─driven by depth-dependent adsorption mechanisms─produces complex spatially variable retardation profiles. We develop vadose zone retardation potentials to quantify this field-scale heterogeneity and propose vertical integration methods to upscale spatially resolved information for transport modeling. This work highlights the importance of accounting for multiscale and multiprocess heterogeneity for accurately describing and predicting the long-term fate and transport of PFAAs in the subsurface.

Developing molecular equations of state to treat electrolyte solutions is challenging due to the long-range nature of the Coulombic interactions. Seminal approaches commonly used are the mean spherical approximation (MSA) and the Debye-Hückel (DH) theory to account for ion-ion interactions and, often, the Born theory of solvation for ion-solvent interactions. We investigate the accuracy of the MSA and DH approaches using each to calculate the contribution of the ion-ion interactions to the chemical potential of NaCl in water, comparing these with newly computer-generated simulation data; the ion-ion contribution is isolated by selecting an appropriate primitive model with a Lennard-Jones force field to describe the solvent. A study of mixtures with different concentrations and ionic strengths reveals that the calculations from both MSA and DH theories are of similar accuracy, with the MSA approach resulting in marginally better agreement with the simulation data. We also demonstrate that the Born theory provides a good qualitative description of the contribution of the ion-solvent interactions; we employ an explicitly polar water model in these simulations. Quantitative agreement up to moderate salt concentrations and across the relevant range of temperature is achieved by adjusting the Born radius using simulation data of the free energy of solvation. We compute the radial and orientational distribution functions of the systems, thereby providing further insight on the differences observed between the theory and simulation. We thus provide rigorous benchmarks for use of the MSA, DH, and Born theories as perturbation approaches, which will be of value for improving existing models of electrolyte solutions, especially in the context of equations of state.

The present study has been undertaken with an objective to find out a suitable medium for the long-term stability and storage of the

Aqueous solubility and interfacial adsorption of surfactants are important for numerous applications. Using molecular dynamics, we have studied the effect of the type of the polar headgroup (cationic quaternary ammonium and charge-neutral amine) and length of the alkyl tail on the hydration free energy of surfactants in infinite dilution. In addition, we have studied the effect of replacing the terminal methyl group of the alkyl tail with a more polar hydroxyl group on the hydration free energy. Quaternary ammonium surfactants have strongly favorable hydration free energies, whereas charge-neutral amine surfactants have unfavorable hydration free energies. The contribution of the quaternary ammonium group in reducing the hydration free energy is estimated to be as large as ∼63

Conventional wisdom suggests that cations play a minimal role in the assembly of cationic amphiphiles. Here, we show that at liquid/liquid (L/L) interfaces, specific cation effects can modulate the assemblies of hydrophobic tails in an oil phase despite being attached to cationic headgroups in the aqueous phase. We used oligo-dimethylsiloxane (ODMS) methyl imidazolium amphiphiles to identify these specific interactions at hexadecane/aqueous interfaces. Small cations, such as Li

We report on a mid-infrared (mid-IR) photothermal spectrometer for liquid-phase samples for the detection of water in organic solvents, such as ethanol or chloroform, and in complex mixtures, such as jet fuel. The spectrometer is based on a Mach-Zehnder interferometer (MZI) employing a He-Ne laser, a mini-flow cell with two embedded channels placed in the interferometer's arms, and a tunable external cavity quantum cascade laser (EC-QCL) for selective analyte excitation in a collinear arrangement. In this study, the bending vibration of water in the spectral range 1565-1725 cm

Coarse-grained water models are ~100 times more efficient than all-atom models, enabling simulations of supercooled water and crystallization. The machine-learned monatomic model ML-BOP reproduces the experimental equation of state (EOS) and ice-liquid thermodynamics at 0.1 MPa on par with all-atom TIP4P/2005 and TIP4/Ice. These all-atom models were parameterized using high-pressure experimental data, and are either accurate for water’s EOS (TIP4P/2005) or ice-liquid equilibrium (TIP4P/Ice). ML-BOP was parameter-ized from temperature-dependent ice and liquid experimental densities and melting data at 0.1 MPa; its only pressure training is from com-pression of TIP4P/2005 ice at 0 K. Here we investigate whether ML-BOP replicates the experimental EOS and ice-water thermodynamics along all pressures of ice I. We find that ML-BOP reproduce the temperature, enthalpy, entropy and volume of melting of hexagonal ice up to 400 MPa and the EOS of water along the melting line with accuracy that rivals both TIP4P/2005 and TIP4P/Ice. We interpret that the accu-racy of ML-BOP originates from its ability to capture the shift between compact and open local structures to changes in pressure and temper-ature. ML-BOP reproduces the sharpening of the tetrahedral peak of the pair distribution function of water upon supercooling, and its pres-sure dependence. We characterize the region of metastability of liquid ML-BOP with respect to crystallization and cavitation. The accessibil-ity of ice crystallization to simulations of ML-BOP, together with its accurate representation of the thermodynamics of water, makes it prom-ising for investigating the interplay between anomalies, glass transition, and crystallization under conditions challenging to access through experiments.

Facilitating photoinduced electron transfer (PET) while minimizing rapid charge-recombination processes to produce a long-lived charge-separated (CS) state represents a primary challenge associated with achieving efficient solar fuel production. Natural photosynthetic systems employ intermolecular interactions to arrange the electron-transfer relay in reaction centers and promote a directional flow of electrons. This work explores a similar tactic through the synthesis and ground- and excited-state characterization of two Cu(I)bis(phenanthroline) chromophores with homoleptic and heteroleptic coordination geometries and which are functionalized with negatively charged sulfonate groups. The addition of sulfonate groups enables solubility in pure water, and it also induces assembly with the dicationic electron acceptor methyl viologen (MV

Fluids leaked from oil and gas wells often originate from their surface casing─a steel pipe installed beneath the deepest underlying source of potable groundwater that serves as the final barrier around the well system. In this study, we analyze a regulatory dataset of surface casing geochemical samples collected from 2573 wells in northeastern Colorado─the only known publicly available dataset of its kind. Thermogenic gas was present in the surface casings of 96.2% of wells with gas samples. Regulatory records indicate that 73.3% of these wells were constructed to isolate the formation from which the gas originated with cement. This suggests that gas migration into the surface casing annulus predominantly occurs through compromised barriers (e.g., steel casings or cement seals), indicative of extensive integrity issues in the region. Water was collected from 22.6% of sampled surface casings. Benzene, toluene, ethylbenzene, and xylenes were detected in 99.7% of surface casing water samples tested for these compounds, which may be due to the presence of leaked oil, natural gas condensate, or oil-based drilling mud. Our findings demonstrate the value of incorporating surface casing geochemical analysis in well integrity monitoring programs to identify integrity issues and focus leak mitigation efforts.

Employing metal-organic frameworks (MOFs) as water adsorbents has become a flourishing field in recent years. Aluminum isophthalate [Al(OH)(

Water is one of the most common components in molecular dynamics (MD) simulations. Using Gaussian process regression for predicting the properties of a water model without the need of running a simulation whenever the parameters are changed, we obtained a flexible polarizable water model, named SWM4/Fw, that is able to reproduce many reference water properties. The added flexibility is critical for modeling chemical reactions in which chemical bonds can be stretched or even broken and for directly calculating vibrational spectra. In addition to being one of the few water models that are both flexible and polarizable, SWM4/Fw is also efficient thanks to the extended Lagrangian scheme with Drude oscillators. The overall accuracy is on par with or better than the related SWM4-NDP model.

Passive water penetration across the cell membrane by osmotic diffusion is essential for the homeostasis of cell volume, in addition to the protein-assisted active transportation of water. Since membrane components can regulate water permeability, controlling compositional variation during the volume regulatory process is a prerequisite for investigating the underlying mechanisms of water permeation and related membrane dynamics. However, the lack of a viable in vitro membrane platform in hypertonic solutions impedes advanced knowledge of cell volume regulation processes, especially cholesterol-enriched lipid domains called lipid rafts. By reconstituting the liquid-ordered (L

International audience; An efficient superhydrophobic concentrator is developed using a hierarchical superhydrophobic surface on which the evaporation of a sessile droplet (6 mu L) drives the nonvolatile elements it contains on a predefined micrometric analytical surface (pedestal of 80 mu m diameter). This hierarchical silicon surface exhibits a surface texture made of etched nanopillars and consists of micropillars and guiding lines, arranged in radial symmetry around the central pedestal. The guiding lines ensure the overall convergence of the sessile droplet toward the central pedestal during evaporation. The nanopillar texturing induced a delay in the Cassie-Baxter to Wenzel regime transition, until the edge of the droplet reaches the periphery of the pedestal. Experiments performed with polymer microparticles suspended in ultrapure water or with DNA molecules solubilized in ultrapure water at sub-fM concentrations demonstrated that the totality of the nonvolatile elements in the liquid microvolume is delivered on or close to the pedestal area, in a very reproducible manner. The very high concentration capacity of the device enabled the discrimination of the degree of purity of ultrapure water samples from different origins. The concentrator also turned out to be functional for raw water samples, opening possible applications to environmental analysis.

The online coupling technique of sample preparation with chromatography is a frontier topic in analytical chemistry since it minimizes errors caused by sample loss, shortens analysis time, and reduces solvent consumption. An online pressure change focusing-supercritical fluid selective extraction chromatography (PCF-SFSEC) technique was developed in this study, realizing extraction, purification, separation, and detection in a single run with only microliter-scale samples. The pressure change focusing strategy achieved column-head stacking by decreasing the dissolving capacity of the supercritical fluid, enabling the large volume introduction of extractants into supercritical fluid chromatography without causing peak broadening or distortion. All the extracts could be directly loaded into the chromatography system without split flow. Based on the supercritical fluid selective extraction (SFSE) strategy, the sorbents removed interferences and water from samples, effectively alleviating matrix effects and realizing the direct aqueous sample analysis. The efficiency of online PCF-SFSEC was demonstrated by the enantioselective analysis of 22 chiral drugs in rat plasma, covering eight categories with different pharmacological effects. The entire analysis took 25 min, consuming only 5 μL samples. All analytes in PCF-SFSEC obtained sharp and symmetrical peaks with resolutions higher than 1.0, and 86% had resolutions higher than 1.5. Limits of quantification (LOQs) ranged from 0.0600 to 32.1 μg/L. Recoveries were in the range of 75.8-117.2%. In addition, the developed approach obtained more satisfactory repeatability and significantly reduced matrix effects than conventional methods. The newly established online PCF-SFSEC technique is believed to be a green and powerful tool for the chiral analysis of complex samples.

Currently, one of the main reasons for the ineffectiveness of tumor treatment is that the abnormally high tumor interstitial pressure (TIP) hinders the delivery of drugs to the tumor center and promotes intratumoral cell survival and metastasis. Herein, we designed a "nanomotor" by in situ growth of Ag

Dehydration has always been a confusing problem for a hydrogel exposed to air, which restricts its application in practical detection. While an ionogel with unique properties can lock water molecules efficiently due to its low vapor pressure, the design and development of an ionogel with excellent water-locking properties and stability to achieve satisfactory detection are thus highly desirable. In this work, a pH-sensitive, stretchable, antibacterial, and stable ionogel artificial tongue was fabricated through dual cross-linking. The artificial tongue consisted of MXene as a cross-linking agent, phenol red as an indicator, gelatin, N-(2-hydroxyethyl) acrylamide, and 1-butyl-3-methylimidazolium chloride as the three-dimensional polymer network. A small quantity of MXene was used as a cross-linker the first time to promote the initiator in the system to generate free radicals, accelerating the reaction process and the multilevel linkage among the polymers. Meanwhile, the indicator phenol red was introduced into the ionogel successfully for the first time, showing great stability in 5 weeks. After evaluation by the Brand-Altman analysis, it was found that the method of pH measurement using ionogels had good consistency with the pH meter measurement method. Additionally, the prepared ionogel presented excellent water retention, mechanical stretchability, antibacterial property, and stability, as well as good test results in the test of artificial simulated saliva, demonstrating great potential in clinical applications.

ConspectusIn nature, cells are highly compartmentalized into many organelles that are well separated from the rest of the cellular space by unique membrane structures, which are of crucial importance to allow cells to perform various physiological functions in such a small and crowded space. Learning from the ubiquitous membrane structures of cells and organelles has continuously inspired the development of artificial self-assembled nanostructures, with lipid vesicles (liposomes) and polymer vesicles (polymersomes) being the most representative examples. Similar to the membrane-bound structures of cells and organelles, both liposomes and polymersomes contain an aqueous interior enclosed by a bilayer membrane. Therefore, liposomes and polymersomes have been extensively investigated to mimic the fundamental structures and functions of living cells. For example, liposomes and polymersomes have been successfully engineered as nanocarriers, smart nanoreactors, artificial organelles, and so on. Notably, living cells can exchange both energy and materials with surrounding environments, benefiting from the selective permeability of lipid membranes. The permselectivity of cell membranes is thus an essential attribute of living organisms. Compared to liposomes, polymersomes have increased structural stability but low membrane permeability. Indeed, polymersomes are almost impermeable to small molecules, ions, and even water molecules. To improve the permeability of polymersomes, much effort has been devoted to the incorporation of channel proteins, the coassembly of oppositely charged block copolymers (BCPs), the development of stimuli-responsive BCPs, and so on. Despite great achievements, these approaches generally lead to decreased stability of polymersomes and, sometimes, polymersome disintegration. In this Account, we discuss our recent efforts to reconcile the stability and permeability of polymersomes via a traceless cross-linking approach. Although cross-linking reactions within bilayer membranes generally lead to decreased permeability, the traceless cross-linking approach can concurrently improve the stability and permeability of polymersomes. Specifically, stimuli-responsive polymersomes undergo either covalent cross-linking or noncovalent cross-linking reactions under specific stimuli to increase bilayer stability, while the cross-linking processes can concurrently permeabilize polymersome bilayers through cross-linking-driven hydrophobic-to-hydrophilic transitions. Notably, unlike conventional cross-linking processes requiring additional cross-linkers, the traceless cross-linking process does not involve extra cross-linking agents but takes full advantage of the in situ generated active moieties. By taking advantage of the simultaneous modulation of the stability and permeability of polymersomes via traceless cross-linking, these polymersomes can be further engineered as smart nanocarriers and nanoreactors. The robustness and generality of this approach have been validated by both extracellular and intracellular stimuli such as light irradiation, glutathione, and hydrogen peroxide. Moreover, many functional groups such as fluorescent dyes and contrast agents can be integrated into this versatile platform as well, enabling the construction of theranostic nanovectors capable of responding to pathological microenvironments. This Account provides a new approach to regulating the permeability of polymersomes while maintaining their structural stability.

The design of soft robots capable of navigation underwater has received tremendous research interest due to the robots' versatile applications in marine explorations. Inspired by marine animals such as jellyfish, scientists have developed various soft robotic fishes by using elastomers as the major material. However, elastomers have a hydrophobic network without embedded water, which is different from the gel-state body of the prototypes and results in high contrast to the surrounding environment and thus poor acoustic stealth. Here, we demonstrate a manta ray-inspired soft robot fish with tailored swimming motions by using tough and stiff hydrogels as the structural elements, as well as a dielectric elastomer as the actuating unit. The switching between actuated and relaxed states of this unit under wired power leads to the flapping of the pectoral fins and swimming of the gel fish. This robot fish has good stability and swims with a fast speed (∼10 cm/s) in freshwater and seawater over a wide temperature range (4-50 °C). The high water content (i.e., ∼70 wt %) of the robot fish affords good optical and acoustic stealth properties under water. The excellent mechanical properties of the gels also enable easy integration of other functional units/systems with the robot fish. As proof-of-concept examples, a temperature sensing system and a soft gripper are assembled, allowing the robot fish to monitor the local temperature, raise warning signals by lighting, and grab and transport an object on demand. Such a robot fish should find applications in environmental detection and execution tasks under water. This work should also be informative for the design of other soft actuators and robots with tough hydrogels as the building blocks.

The hydrogen bonding interaction between the amide functional group and water is fundamental to understanding the liquid-liquid heterogeneity in biological systems. Herein, the structure and dynamics of the

Atomic layer coating (ALC) is emerging as a particle engineering strategy to inhibit surface crystallization of amorphous solid dispersions (ASDs). In this study, we turn our attention to evaluating drug release behavior from ALC-coated ASDs, and begin to develop a mechanistic framework. Posaconazole/hydroxypropyl methylcellulose acetate succinate was used as a model system at both 25% and 50% drug loadings. ALC-coatings of aluminum oxide up to 40 nm were evaluated for water sorption kinetics and dissolution performance under a range of pH conditions. Scanning electron microscopy with energy dispersive X-ray analysis was used to investigate the microstructure of partially released ASD particles. Coating thickness and defect density (inferred from deposition rates) were found to impact water sorption kinetics. Despite reduced water sorption kinetics, the presence of a coating was not found to impact dissolution rates under conditions where rapid drug release was observed. Under slower releasing conditions, underlying matrix crystallization was reduced by the coating, enabling greater levels of drug release. These results demonstrate that water was able to penetrate through the ALC coating, hydrating the amorphous solid, which can initiate dissolution of drug and/or polymer (depending on pH conditions). Swelling of the ASD substrate subsequently occurs, disrupting and cracking the coating, which serves to facilitate rapid drug release. Water sorption kinetics are highlighted as a potential predictive tool to investigate the coating quality and its potential impact on dissolution performance. This study has implications for formulation design and evaluation of ALC-coated ASD particles.

The interactions of heavy metals with minerals influence the mobility and bioavailability of toxic elements in natural aqueous environments. The sorption of heavy metals on covalently bonded minerals is generally well described by surface complexation models (SCMs). However, understanding sorption on sparingly soluble minerals is challenging because of the dynamically evolving chemistry of sorbent surfaces. The interpretation can be even more complicated when multiple metal ions compete for sorption. In the present study, we observed synergistically enhanced uptake of lead and selenate on the barite (001) surface through two sorption mechanisms: lattice incorporation that dominates at lower coverages and two-dimensional monolayer growth that dominates at higher coverages. We also observed a systematic increase in the sorption affinity with increasing co-sorbed ion coverages, different from the assumption of invariant binding constants for individual adsorption processes in classical SCMs. Computational simulations showed thermodynamically favorable co-incorporation of lead and selenate by simultaneously substituting for barium and sulfate in neighboring sites, resulting in the formation of molecular clusters that locally match the net dimension of the substrate lattice. These results emphasize the importance of ion-ion interactions at mineral-water interfaces that control the fate and transport of contaminants in the environment.

This Feature Article starts highlighting some recent experimental and theoretical advances in the field of IR and Raman spectroscopy, giving a taste of the breadth and dynamics of this striving field. The local mode theory is then reviewed, showing how local vibrational modes are derived from fundamental normal modes. New features are introduced that add to current theoretical efforts: (i) a unique measure of bond strength based on local mode force constants ranging from bonding in single molecules in different environments to bonding in periodic systems and crystals and (ii) a new way to interpret vibrational spectra by pinpointing and probing interactions between particular bond stretching contributions to the normal modes. All of this represents a means to work around the very nature of normal modes, namely that the vibrational motions in polyatomic molecules are delocalized. Three current focus points of the local mode analysis are reported, demonstrating how the local mode analysis extracts important information hidden in vibrational spectroscopy data supporting current experiments: (i) metal-ligand bonding in heme proteins, such as myoglobin and neuroglobin; (ii) disentanglement of DNA normal modes; and (iii) hydrogen bonding in water clusters and ice. Finally, the use of the local mode analysis by other research groups is summarized. Our vision is that in the future local mode analysis will be routinely applied by the community and that this Feature Article serves as an incubator for future collaborations between experiment and theory.

In situ rapid detection of contaminants in environmental water is crucial for protecting the ecological environment and human health; however, it is always hindered by the complexity of sample matrices, trace content, and unknown species. Herein, we demonstrate a deep learning-based multicapturer surface-enhanced Raman scattering (SERS) platform on plasmonic nanocube metasurfaces for multiplex determination of organophosphorus pesticides (OPPs) residues. Poly(vinylpyrrolidone), 4-mercaptobenzoic acid, and l-cysteine are assembled on Ag nanocubes (AgNCs) and act as capturers to chemically define OPPs. Meanwhile, the OPPs-captured AgNCs efficiently close the interparticle distance and generate plasmonic metasurfaces, guaranteeing ultrasensitive and reproducible SERS analysis. Furthermore, by strategically combining all capturer-OPP SERS spectra, comprehensive "combined-SERS spectra" are reconstructed to enhance spectral variations of each OPP. Based on the combined-SERS spectra, a deep learning model is trained to predict OPPs, which significantly improve the qualitative and quantitative analysis accuracy. We successfully identified multiple OPPs in farmland, river, and fishpond water using this strategy. The whole detection procedure requires only 30 min, including sampling, SERS measurements, and deep learning analyses. This combination of a multicapturer SERS platform with the deep learning algorithm creates a rapid and reliable analytical strategy for multiplex detection of target molecules, providing a potential paradigm shift for environment-related research.

Silk fibroin is widely believed to be sustainable, biocompatible, and biodegradable, providing promising features such as carriers to deliver drugs and functional ingredients in food, personal care, and biomedical areas, which are consistent with emulsion characteristics; especially, green, all-natural biopolymer-based stabilizers are in great demand to stabilize Pickering emulsions and match the multifunctional needs for developing ideal materials. Herein, an unprecedented three-dimensional (3D) nanostructure, namely a brush-like silk nanobrush (SNB), is applied as the stabilizer to formulate and stabilize Pickering emulsions. The size and interfacial tension are compared among the SNB, a regenerated silk nanofiber, and a nanowhisker. Additionally, optimization processes are conducted to determine the ideal ultrasonication intensity and SNB concentration required to prepare Pickering emulsions by analyzing the morphology, creaming index, mean oil droplet size, and rheological behavior. The results indicate that an SNB with the characteristic structure and suitable size shows superior potential to form sophisticated and interconnected networks in oil-water interfaces, and is proved to be able to resist creaming at a wide range of concentrations and subsequently stabilize Pickering emulsions from liquid-like emulsions to gel-like emulsions. Additionally, SNB is proved to be biocompatible according to cell experiments, providing a promising alternative in designing all-natural, green, and biocompatible emulsions with the aim of efficiently delivering nutrients or drugs associated with health benefits.

The misuse of organic pollutants such as nitrofuran antibiotics (NFAs) and 2,6-dichloro-4-nitroaniline (DCN) has become a hot topic of global concern, and developing rapid, efficient, and accurate techniques for detecting NFAs and pesticides in water is a major challenge. Here, we designed a novel lead-based anion 2D metal-organic framework (MOF){[(CH

We investigate the molecular origin of the fluorescence Stokes shift in an aqueous liquid. By examining the speed of energy change, the solvation response function is explicitly projected onto the translational and rotational motions of water molecules for both nonequilibrium relaxation and equilibrium fluctuations. Molecular dynamics simulations of a tryptophan solution show that these two processes have highly consistent dynamics, not only for the total response function but also for the decomposed components in terms of specific molecular movements. We found that the rotational mode governs the relaxation of the Stokes shift, whereas the translational mode contributes non-negligibly with slower dynamics. This consistency implies the similarity of the underlying translational and rotational movements of water molecules as the system is far away from and at equilibrium, supporting the validity of the linear response theory at the molecular level. The decomposition methodology is also applicable to a rigid solvent.

Developing an economical and robust sensor using an earth-abundant metal-based metal-organic framework (MOF) to detect trace water content rapidly is crucial for laboratories and chemical industries. Herein, a mixed-valent chiral [{Cu

In view of the high risks brought about by organic micropollutants (OMPs), nanofiltration (NF) processes have been playing a vital role in advanced water and wastewater treatment, owing to the high membrane performance in rejection of OMPs, permeation of water, and passage of mineral salts. Though numerous studies have been devoted to evaluating and technically enhancing membrane performance in removing various OMPs, the trade-off effect between water permeance and water/OMP selectivity for state-of-the-art membranes remains far from being understood. Knowledge of this effect is significant for comparing and guiding membrane development works toward cost-efficient OMP removal. In this work, we comprehensively assessed the performance of 88 NF membranes, commercialized or newly developed, based on their water permeance and OMP rejection data published in the literature. The effectiveness and underlying mechanisms of various modification methods in tailoring properties and in turn performance of the mainstream polyamide (PA) thin-film composite (TFC) membranes were quantitatively analyzed. The trade-off effect was demonstrated by the abundant data from both experimental measurements and machine learning-based prediction. On this basis, the advancement of novel membranes was benchmarked by the performance upper-bound revealed by commercial membranes and lab-made PA membranes. We also assessed the potentials of current NF membranes in selectively separating OMPs from inorganic salts and identified the future research perspectives to achieve further enhancement in OMP removal and salt/OMP selectivity of NF membranes.

Plant polyphenol-inspired surface modification of membranes is helpful for oil-water separation. However, the preparation of this coating is time-consuming. Herein, we introduce a rapid synthesis of the TA-APTES coating by the addition of sodium periodate (SP). The surface chemical composition and morphology of the resultant TA-APTES hybrid coatings were characterized using SEM, ATR-FTIR, and XPS. The hydrophilicity and membrane performance were investigated by the water contact angle, pure water permeability, and oil rejection for an isooctane-in-water emulsion. The experimental findings revealed that the optimal microfiltration (MF) membrane (MF-TA-APTES-SP-0.05) displayed exceptional hydrophilicity and water permeability (9558 L m

Protein crystals composed of protein molecules are expected as a novel porous material. They have high porosity, and the knowledge of the diffusion of intracrystalline water is important. In this study, the diffusion coefficient of intracrystalline water in intrinsic hen egg-white lysozyme (HEWL) crystals was determined by a method that combines confocal Raman spectroscopy and air convection with controlled relative humidity. Similar to common porous materials, the drying process of the protein crystals includes three periods: constant-rate drying, falling-rate drying, and equilibrium state. During the falling-rate drying period, the drying rate depends on the diffusion of intracrystalline water in the protein crystal. The gradient of the water content was measured using confocal Raman spectroscopy. The diffusion coefficient of the intrinsic HEWL crystals was determined as 3.1 × 10