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Aqueous two-phase systems (ATPSs), phase-separating solutions of water soluble but mutually immiscible molecular species, offer fascinating prospects for selective partitioning, purification, and extraction. Here, we formulate a general Brownian dynamics based coarse-grained simulation model for an ATPS of two water soluble but mutually immiscible polymer species. Including additional solute species into the model is straightforward, which enables capturing the assembly and partitioning response of, e.g., nanoparticles (NPs), additional macromolecular species, or impurities in the ATPS. We demonstrate that the simulation model captures satisfactorily the phase separation, partitioning, and interfacial properties of an actual ATPS using a model ATPS in which a polymer mixture of dextran and polyethylene glycol (PEG) phase separates, and magnetic NPs selectively partition into one of the two polymeric phases. Phase separation and NP partitioning are characterized both via the computational model and experimentally, under different conditions. The simulation model captures the trends observed in the experimental system and quantitatively links the partitioning behavior to the component species interactions. Finally, the simulation model reveals that the ATPS interface fluctuations in systems with magnetic NPs as a partitioned species can be controlled by the magnetic field at length scales much smaller than those probed experimentally to date., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.)

Mixed-linkage glucans are major components of grassy cell-walls and cereal endosperm. Recently identified plant endo-β-glucanase from the EG16 family cleaves MLGs with strong specificity towards regions with at least four sequential β(1,4)-linked glucose residues. This activity yields a low molecular-weight MLG with a repeating structure of β(1,3)-linked cellotriose that gels rapidly at concentrations as low as 1.0 % w/v. To understand the gelation mechanism, we investigated the structure and behavior using rheology, microscopy, X-ray scattering, and molecular dynamics simulations. Upon digestion, the material's rheological behavior changes from typical polymeric material to a fibrillar network behavior seen for e.g. cellulose nanofibrils. Scanning electron microscopy and confocal microscopy verifies these changes in micro- and nanostructure. Small-angle X-ray scattering shows in-solution self-assembly of MLG through ~10 nm elemental structures. Wide-angle X-ray scattering data indicate that the polymer association is similar to cellulose II, with dominant scattering at d-spacing of 0.43 nm. Simulations of two interacting glucan chains show that β(1,3)-linkages prevent the formation of tight helices that form between β(1,4)-linked d-glucan chains, leading to weaker interactions and less ordered inter-chain assembly. Overall, these data indicate that digestion drives gelation not by enhancement of interactions driving self-assembly, but by elimination of unproductive interactions hindering self-assembly., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Polyelectrolyte complexes (PECs) have attracted considerable attention owing to their unique physicochemical properties and potential applications as smart materials. Herein, the glass transitions of PECs solvated with varying alcohols are investigated in poly(diallyldimethylammonium)/poly(acrylic acid) (PDADMA/PAA) complexes by using modulated differential scanning calorimetry (MDSC). Solvents with one or two hydroxyl groups are selected to examine the effect of PAA-solvent interactions on the glass transition temperature ( T g ). Except for glycerol, all alcohol solvents yield PECs with detectable T and the natural logarithm of the number of hydroxyl groups to intrinsic ion pair ratio [ln( g 's and plasticization behavior. Furthermore, a linear relationship for 1/ T )] is found. This result is significant because prior work demonstrated the relationship only for water and no other solvents. All-atom molecular dynamics (MD) simulations analyze the ability of the solvent to form hydrogen bonds via the solvent's OH groups to the PAA, revealing that the solvent molecule size and available hydroxyl groups govern the change in the glass transition. Overall, the clear dependence of a PEC's glass transition on the solvent's chemical structure provides a simple guideline for predicting their relationship.g and the natural logarithm of the number of hydroxyl groups to intrinsic ion pair ratio [ln( n hydroxyl / n intrinsic-ion-pair )] is found. This result is significant because prior work demonstrated the relationship only for water and no other solvents. All-atom molecular dynamics (MD) simulations analyze the ability of the solvent to form hydrogen bonds via the solvent's OH groups to the PAA, revealing that the solvent molecule size and available hydroxyl groups govern the change in the glass transition. Overall, the clear dependence of a PEC's glass transition on the solvent's chemical structure provides a simple guideline for predicting their relationship., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

We examine the interactions between polyelectrolytes (PEs) and uncharged substrates under conditions corresponding to a dielectric discontinuity between the aqueous solution and the substrate. To this end, we vary the relevant system characteristics, in particular the substrate dielectric constant ɛs under different salt conditions. We employ coarse-grained molecular dynamics simulations with rodlike PEs in salt solutions with explicit ions and implicit water solvent with dielectric constant ɛw = 80. As expected, at low salt concentrations, PEs are repelled from the substrates with ɛs < ɛw but are attracted to substrates with a high dielectric constant due to image charges. This attraction considerably weakens for high salt and multivalent counterions due to enhanced screening. Furthermore, for monovalent salt, screening enhances adsorption for weakly charged PEs, but weakens it for strongly charged ones. Meanwhile, multivalent counterions have little effect on weakly charged PEs, but prevent adsorption of highly charged PEs, even at low salt concentrations. We also find that correlation-induced charge inversion of a PE is enhanced close to the low dielectric constant substrates, but suppressed when the dielectric constant is high. To explore the possibility of a PE monolayer formation, we examine the interaction of a pair of like-charged PEs aligned parallel to a high dielectric constant substrate with ɛs = 8000. Our main conclusion is that monolayer formation is possible only for weakly charged PEs at high salt concentrations of both monovalent and multivalent counterions. Finally, we also consider the energetics of a PE approaching the substrate perpendicular to it, in analogy to polymer translocation. Our results highlight the complex interplay between electrostatic and steric interactions and contribute to a deeper understanding of PE-substrate interactions and adsorption at substrate interfaces with varying dielectric discontinuities from solution, ubiquitous in biointerfaces, PE coating applications, and designing adsorption setups., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Ion-specific effects on aqueous solvation of monovalent counter ions, Na + ${^+ }$ , K + ${^+ }$ , Cl - ${^- }$ , and Br - ${^- }$ , and two model polyelectrolytes (PEs), poly(styrene sulfonate) (PSS) and poly(diallyldimethylammonium) (PDADMA) were here studied with ab initio molecular dynamics (AIMD) and classical molecular dynamics (MD) simulations based on the OPLS-aa force-field which is an empirical fixed point-charge force-field. Ion-specific binding to the PE charge groups was also characterized. Both computational methods predict similar response for the solvation of the PEs but differ notably in description of ion solvation. Notably, AIMD captures the experimentally observed differences in Cl - ${^- }$ and Br - ${^- }$ anion solvation and binding with the PEs, while the classical MD simulations fail to differentiate the ion species response. Furthermore, the findings show that combining AIMD with the computationally less costly classical MD simulations allows benefiting from both the increased accuracy and statistics reach., (© 2024 The Authors. ChemPhysChem published by Wiley-VCH GmbH.)

The coacervation and complexation of oppositely charged polyelectrolytes are dependent on numerous environmental and preparatory factors, but temperature is often overlooked. Temperature effects remain unclear because the temperature dependence of both the dielectric constant and polymer-solvent interaction parameter can yield lower and/or upper critical solution phase behaviors for PECs. Further, secondary interactions, such as hydrogen bonding, can affect the temperature response of a PEC. That is, mixtures of oppositely charged polyelectrolytes can exhibit phase separation upon lowering and/or increasing the mixture's temperature. Here, the phase behavior of poly(diallylmethylammonium)/poly(acrylic acid) (PDADMA/PAA) complexes under varying KBr ionic strengths, mixing ratios, and temperatures at a fixed pH (in which PAA hydrogen bonding can occur) is examined. At room temperature, the PDADMA/PAA PECs exhibit four different phase states: precipitate, coexisting precipitate and coacervate, solid-like gel, and coacervate. Variable-temperature optical microscopy reveals the upper critical solution temperature (UCST) at which each phase transitioned to a solution state. Interestingly, the UCST value is highly dependent on the original phase of the PEC, in which solid-like precipitates exhibit higher UCST values. Large-scale all-atom molecular dynamics (MD) simulations support that precipitates exhibit kinetic trapping, which may contribute to the higher UCST values observed in the experiment. Taken together, this study highlights the significance of temperature on the phase behavior of PECs, which may play a larger role in stimuli-responsive materials, membraneless organelles, and separations applications., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

It is well established that when multivalent counterions or salts are added to a solution of highly charged polyelectrolytes (PEs), correlation effects can cause charge inversion of the PE, leading to electrophoretic mobility (EM) reversal. In this work, we use coarse-grained molecular-dynamics simulations to unravel the less understood effect of coion valency on EM reversal for rigid DNA-like PEs. We find that EM reversal induced by multivalent counterions is suppressed with increasing coion valency in the salt added and eventually vanishes. Further, we find that EM is enhanced at fixed low salt concentrations for salts with monovalent counterions when multivalent coions with increasing valency are introduced. However, increasing the salt concentration causes a crossover that leads to EM reversal which is enhanced by increasing coion valency at high salt concentration. Remarkably, this multivalent coion-induced EM reversal persists even for low values of PE linear charge densities where multivalent counterions alone cannot induce EM reversal. These results facilitate tuning PE-PE interactions and self-assembly with both coion and counterion valencies.

Future sustainable materials based on designer biomolecules require control of the solution assembly, but also interfacial interactions. Alcohol treatments of protein materials are an accessible means to this, making understanding of the process at the molecular level of seminal importance. We focus here on the influence of ethanol on spidroins, the main proteins of silk. By large-scale atomistically detailed molecular dynamics (MD) simulations and interconnected experiments, we characterize the protein aggregation, secondary structure changes, molecular level origins of them, and solvation environment changes for the proteins, as induced by ethanol as a solvation additive. The MD and circular dichoroism (CD) findings jointly show that ethanol promotes ordered structure in the protein molecules, leading to an increase of helix content and turns but also increased aggregation, as revealed by dynamic light scattering (DLS) and light microscopy. The structural changes correlate at the molecular level with increased intramolecular hydrogen bonding. The simulations reveal that polar amino acids, such as glutamine and serine, are most influenced by ethanol, whereas glycine residues are most prone to be involved in the ethanol-induced secondary structure changes. Furthermore, ethanol engages in interactions with the hydrophobic alanine-rich regions of the spidroin, significantly decreasing the hydrophobic interactions of the protein with itself and its surroundings. The protein solutes also change the microstructure of water/ethanol mixtures, essentially decreasing the level of larger local clustering. Overall, the work presents a systematic characterization of ethanol effects on a widely used, common protein type, spidroins, and generalizes the findings to other intrinsically disordered proteins by pinpointing the general features of the response. The results can aid in designing effective alcohol treatments for proteins, but also enable design and tuning of protein material properties by a relatively controllable solvation handle, the addition of ethanol.

Polyelectrolyte multilayers (PEMs) or polyelectrolyte complexes (PECs), formed by layer-by-layer assembly or the mixing of oppositely charged polyelectrolytes (PEs) in aqueous solution, respectively, have potential applications in health, energy, and the environment. PEMs and PECs are very tunable because their structure and properties are influenced by factors such as pH, ionic strength, salt type, humidity, and temperature. Therefore, it is increasingly important to understand how these factors affect PECs and PEMs on a molecular level. In this Feature Article, we summarize our contributions to the field in the development of approaches to quantify the swelling, thermal properties, and dynamic mechanical properties of PEMs and PECs. First, the role of water as a plasticizer and in the glass-transition temperature ( T ) in both strong poly(diallyldimethylammonium)/poly(sodium 4-styrenesulfonate) (PDADMA/PSS) and weak poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) systems is presented. Then, factors influencing the dynamics of PECs and PEMs are discussed. We also reflect on the swelling of PEMs in response to different salts and solvent additives. Last, the nature of water's microenvironment in PEMs/PECs is discussed. A special emphasis is placed on experimental techniques, along with molecular simulations. Taken together, this review presents an outlook and offers recommendations for future research directions, such as studying the additional effects of hydrogen-bonding hydrophobic interactions.g ) in both strong poly(diallyldimethylammonium)/poly(sodium 4-styrenesulfonate) (PDADMA/PSS) and weak poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) systems is presented. Then, factors influencing the dynamics of PECs and PEMs are discussed. We also reflect on the swelling of PEMs in response to different salts and solvent additives. Last, the nature of water's microenvironment in PEMs/PECs is discussed. A special emphasis is placed on experimental techniques, along with molecular simulations. Taken together, this review presents an outlook and offers recommendations for future research directions, such as studying the additional effects of hydrogen-bonding hydrophobic interactions.

Structural engineering of molecules for condensation is an emerging technique within synthetic biology. Liquid-liquid phase separation of biomolecules leading to condensation is a central step in the assembly of biological materials into their functional forms. Intracellular condensates can also function within cells in a regulatory manner to facilitate reaction pathways and to compartmentalize interactions. We need to develop a strong understanding of how to design molecules for condensates and how their in vivo- in vitro properties are related. The spider silk protein NT2RepCT undergoes condensation during its fiber-forming process. Using parallel in vivo characterization, in this study, we mapped the effects of intracellular conditions for NT2RepCT and its several structural variants. We found that intracellular conditions may suppress to some extent condensation whereas molecular crowding affects both condensate properties and their formation. Intracellular characterization of protein condensation allowed experiments on pH effects and solubilization to be performed within yeast cells. The growth of intracellular NT2RepCT condensates was restricted, and Ostwald ripening was not observed in yeast cells, in contrast to earlier observations in in vitro . Our results lead the way to using intracellular condensation to screen for properties of molecular assembly. For characterizing different structural variants, intracellular functional characterization can eliminate the need for time-consuming batch purification and E. coli . Our results lead the way to using intracellular condensation to screen for properties of molecular assembly. For characterizing different structural variants, intracellular functional characterization can eliminate the need for time-consuming batch purification and in vitro condensation. Therefore, we suggest that the in vivo - in vitro understanding will become useful in, e.g., high-throughput screening for molecular functions and in strategies for designing tunable intracellular condensates.

The self-assembly of dioctyl sodium sulfosuccinate (AOT) model surfactant in solvent environments of differing polarity is examined by means of dissipative particle dynamics (DPD) bead model parametrized against Hildebrand solubility parameters from atomistic molecular dynamics (MD) simulations. The model predicts that in hydrophobic solvents ( e.g. dodecane) the surfactant forms small ( N ∼ 8) reverse micellar aggregates, while in a solvent corresponding to water lamellar assembly takes place, in good agreement with literature structural parameters. Interestingly, solvents of intermediate polarity lead to formation of large, internally structured aggregates. In these, the surfactant headgroups cluster within the aggregate, surrounded by a continuous phase formed by the hydrocarbon tails. We show that the partitioning of the headgroups between the aggregate surface layer and the inner clustered phase depends primarily on solvent polarity, and can be controlled by the solvent, but also system composition. Finally, we compare the DPD assembly response to simplified effective interaction potentials derived at dilute concentration limit for the interactions. The comparison reveals that the simplified effective potential descriptions provide good level of insight on the assembly morphologies, despite drastic, isotropic interactions simplification involved.agg ∼ 8) reverse micellar aggregates, while in a solvent corresponding to water lamellar assembly takes place, in good agreement with literature structural parameters. Interestingly, solvents of intermediate polarity lead to formation of large, internally structured aggregates. In these, the surfactant headgroups cluster within the aggregate, surrounded by a continuous phase formed by the hydrocarbon tails. We show that the partitioning of the headgroups between the aggregate surface layer and the inner clustered phase depends primarily on solvent polarity, and can be controlled by the solvent, but also system composition. Finally, we compare the DPD assembly response to simplified effective interaction potentials derived at dilute concentration limit for the interactions. The comparison reveals that the simplified effective potential descriptions provide good level of insight on the assembly morphologies, despite drastic, isotropic interactions simplification involved.

We explore here the assembly and adsorption response of a ternary bio oil-phospholipid-water system via dissipative particle dynamics (DPD) simulations. The mesoscale, particle-based modelling approach allows the examination of large-scale self-assembly response of dipalmitoylphosphatidylcholine (DPPC) phospholipids in a model bio oil solvent (modelled by triglycerides) in the presence of varying amounts of water. We report the reverse micellar and microemulsion assembly phase diagrams of the ternary mixture, verifying the model against literature data. The results show water content vs phospholipid concentration dependent transitions in reverse micellar to network-like and various lamellar phases in bulk assembly. Examination of the DPPC adsorption to smooth, homogeneous adsorbate surfaces of differing polarity reveals that phospholipid adsorption response transitions between discrete assemblies on polyethylene-like hydrophobic to continuous coating on mica-like hydrophilic substrates as the function of phospholipid and water concentrations. The significance of the work is that the presented model for phospholipid assembly in apolar solvents is capable of predicting accurately large scale assembly response and morphology changes including adsorption response in terms of system variables. The presented parametrization and verification information of the model enable readily extending the approach to other systems. The work provides computational access for tuning lipid-based microemulsion systems and their adsorption.

We show by extensive experimental characterization combined with molecular simulations that pH has a major impact on the assembly mechanism and properties of poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) complexes. A combination of dynamic light scattering (DLS) and laser Doppler velocimetry (LDV) is used to assess the complexation, charge state, and other physical characteristics of the complexes, isothermal titration calorimetry (ITC) is used to examine the complexation thermodynamics, and circular dichroism (CD) is used to extract the polypeptides' secondary structure. For enhanced analysis and interpretation of the data, analytical ultracentrifugation (AUC) is used to define the precise molecular weights and solution association of the peptides. Molecular dynamics simulations reveal the associated intra- and intermolecular binding changes in terms of intrinsic vs. extrinsic charge compensation, the role of hydrogen bonding, and secondary structure changes, aiding in the interpretation of the experimental data. We combine the data to reveal the pH dependency of PLL/PGA complexation and the associated molecular level mechanisms. This work shows that not only pH provides a means to control complex formation but also that the associated changes in the secondary structure and binding conformation can be systematically used to control materials assembly. This gives access to rational design of peptide materials via pH control.

Hypothesis: The degree of polymerization of amphiphilic di-block co-polymers, which can be varied with ease in computer simulations, provides a means to control self-assembling di-block co-polymer coatings on hydrophilic substrates., Simulations: We examine self-assembly of linear amphiphilic di-block co-polymers on hydrophilic surface via dissipative particle dynamics simulations. The system models a glucose based polysaccharide surface on which random co-polymers of styrene and n-butyl acrylate, as the hydrophobic block, and starch, as the hydrophilic block, forms a film. Such setups are common in e.g. hygiene, pharmaceutical, and paper product applications., Findings: Variation of the block length ratio (35 monomers in total) reveals that all examined compositions readily coat the substrate. However, strongly asymmetric block co-polymers with short hydrophobic segments are best in wetting the surface, whereas approximately symmetric composition leads to most stable films with highest internal order and well-defined internal stratification. At intermediate asymmetries, isolated hydrophobic domains form. We map the sensitivity and stability of the assembly response for a large variety of interaction parameters. The reported response persists for a wide polymer mixing interactions range, providing general means to tune surface coating films and their internal structure, including compartmentalization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Multivalent ions in solutions with polyelectrolytes (PEs) induce electrostatic correlations that can drastically change ion distributions around the PEs and their mutual interactions. Using coarse-grained molecular dynamics simulations, we show how in addition to valency, ion shape and concentration can be harnessed as tools to control rigid like-charged PE-PE interactions. We demonstrate a correlation between the orientational ordering of aspherical ions and how they mediate the effective PE-PE attraction induced by multivalency. The interaction type, strength, and range can thus be externally controlled in ionic solutions. Our results can be used as generic guidelines to tune the self-assembly of like-charged polyelectrolytes by variation of the characteristics of the ions.

Hypothesis: Multicore block copolymer aggregates correspond to self-assembly such that the polymer system spontaneously phase separates to multiple, droplet-like cores differing in the composition from the polymer surroundings. Such multiple core aggregates are highly useful capsules for different applications, e.g., drug transport, catalysis, controlled solvation, and chemical reactions platforms. We postulate that polymer system composition provides a direct means for designing polymer systems that self-assemble to such morphologies and controlling the assembly response., Simulations: Using dissipative particle dynamics (DPD) simulations, we examine the self-assembly of a mixture of highly and weakly solvophobic homopolymers and an amphiphilic block copolymer in the presence of solvent. We map the multicore vs single core (core-shell particles) assembly response and aggregate structure in terms of block copolymer concentration, polymer component ratios, and chain length of the weakly solvophobic homopolymer., Findings: For fixed components and polymer chemistries, the amount of block copolymer is the key to controlling single core vs multicore aggregation. We find a polymer system dependent critical copolymer concentration for the multicore aggregation and that a minimum level of incompatibility between the solvent and the weakly solvophobic component is required for multicore assembly. We discuss the implications for polymer system design for multicore assemblies. In summary, the study presents guidelines to produce multicore aggregates and to tune the assembly from multicore aggregation to single core core-shell particles., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Maria Sammalkorpi reports financial support was provided by Kemira Oyj. Sousa Javan Nikkhah reports financial support was provided by Kemira Oyj]., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Electrophoretic (EP) mobility reversal is commonly observed for strongly charged macromolecules in multivalent salt solutions. This curious effect takes place, e.g., when a charged polymer, such as DNA, adsorbs excess counterions so that the counterion-dressed surface charge reverses its sign, leading to the inversion of the polymer drift driven by an external electric field. In order to characterize this seemingly counterintuitive phenomenon that cannot be captured by electrostatic mean-field theories, we adapt here a previously developed strong-coupling-dressed Poisson-Boltzmann approach to the cylindrical geometry of the polyelectrolyte-salt system. Within the framework of this formalism, we derive an analytical polymer mobility formula dressed by charge correlations. In qualitative agreement with polymer transport experiments, this mobility formula predicts that the increment of the monovalent salt, the decrease of the multivalent counterion valency, and the increase of the dielectric permittivity of the background solvent suppress charge correlations and increase the multivalent bulk counterion concentration required for EP mobility reversal. These results are corroborated by coarse-grained molecular dynamics simulations showing how multivalent counterions induce mobility inversion at dilute concentrations and suppress the inversion effect at large concentrations. This re-entrant behavior, previously observed in the aggregation of like-charged polymer solutions, calls for verification by polymer transport experiments.

An equilibrium state model addressing the aggregation and adsorption of colloidal assemblies in apolar solvents (oils) via monomer exchange is presented. The model is based on the previously reported step-wise aggregation response of fatty acids and monoglycerides in bio-oils, and captures surface crowding via scaled particle theory (SPT). The sensitivity of key observables - mean aggregation number, adsorbed surfactant amount, and free monomer concentration - to model parameters is demonstrated. Fits to molecular modelling based aggregation and adsorption data of oleic acid and monoolein reveal that the model accurately reproduces chemically specific aggregate exponential distributions in both bulk and surface phases, even outside of its parameterization conditions. A biased state model, where the initial bulk aggregation step (dimer formation) differs from other steps results in a notable improvement in accuracy. Fits to various phospholipid adsorption isotherms demonstrate the applicability of the model to isotherm type experimental data. The fits reveal either monolayer or aggregate like adsorption structures, depending on surfactant head group charge. The presented model provides an easily accessible, computationally feasible means to estimate colloidal assembly and adsorption in oil environments, and enables assessment of surfactant aggregation propensity and adsorption energetics., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

We use the recently developed soft-potential-enhanced Poisson-Boltzmann (SPB) theory to study the interaction between two parallel polyelectrolytes (PEs) in monovalent ionic solutions in the weak-coupling regime. The SPB theory is fitted to ion distributions from coarse-grained molecular dynamics (MD) simulations and benchmarked against all-atom MD modelling for poly(diallyldimethylammonium) (PDADMA). We show that the SPB theory is able to accurately capture the interactions between two PEs at distances beyond the PE radius. For PDADMA positional correlations between the charged groups lead to locally asymmetric PE charge and ion distributions. This gives rise to small deviations from the SPB prediction that appear as short-range oscillations in the potential of mean force. Our results suggest that the SPB theory can be an efficient way to model interactions in chemically specific complex PE systems.

The turn of the twentieth century in Finland saw an increasing number of popular articles and books on health, which were published within the broader framework of 'social hygiene' and aimed at children, young people and their families. This article examines how young people articulated concerns about their own mental health in the context of these campaigns to improve social hygiene. Based on an extensive body of original sources consisting of medical advisory material and letters written by the young, the study reveals how young people saw themselves in this health context-especially when writing about their 'nerves' or 'nervousness'. Drawing on more recent methodological investigations in the history of childhood, this study adds the much-needed perspective of the young people themselves as subjects experiencing these problems, to counterbalance the otherwise exclusively expert discourses on the subject of mental hygiene., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for the Social History of Medicine.)

Water existing within thin polyelectrolyte multilayer (PEM) films has significant influence on their physical, chemical, and thermal properties, having implications for applications including energy storage, smart coatings, and biomedical systems. Ionic strength, salt type, and terminating layer are known to influence PEM swelling. However, knowledge of water's microenvironment within a PEM, whether that water is affiliated with intrinsic or extrinsic ion pairs, remains lacking. Here, we examine the influence of both assembly and post-assembly conditions on the water-ion pair interactions of poly(styrene sulfonate)/poly(diallyldimethylammonium) (PSS/PDADMA) PEMs in NaCl and KBr. This is accomplished by developing a methodology in which quartz crystal microbalance with dissipation monitoring is applied to estimate the number of water molecules affiliated with an ion pair ( i ), as well as the hydration coefficient, π salt . PSS/PDADMA PEMs are assembled in varying ionic strengths of either NaCl and KBr and then exposed post-assembly to increasing ionic strengths of matching salt type. A linear relationship between the total amount of water per intrinsic ion pair and the post-assembly salt concentration was obtained at post-assembly salt concentrations >0.5 M, yielding estimates for both H 2 O . PSS/PDADMA PEMs are assembled in varying ionic strengths of either NaCl and KBr and then exposed post-assembly to increasing ionic strengths of matching salt type. A linear relationship between the total amount of water per intrinsic ion pair and the post-assembly salt concentration was obtained at post-assembly salt concentrations >0.5 M, yielding estimates for both i . We observe higher values of salt H 2 O in KBr-assembled PEMs due to KBr being more effective in doping the assembly because of KBr's more chaotropic nature as compared to NaCl. Lastly, when PSS is the terminating layer, i and π salt molecular dynamics provide a microstructural view as to how NaCl and KBr interact with individual polyelectrolytes and the involved water shells. Put together, this study provides further insight into the understanding of existing water microenvironments in PEMs and the effects of both assembly and post-assembly conditions.H 2 O in KBr-assembled PEMs due to KBr being more effective in doping the assembly because of KBr's more chaotropic nature as compared to NaCl. Lastly, when PSS is the terminating layer, i decreases in value due to PSS's hydrophobic nature. Classical and ab initio molecular dynamics provide a microstructural view as to how NaCl and KBr interact with individual polyelectrolytes and the involved water shells. Put together, this study provides further insight into the understanding of existing water microenvironments in PEMs and the effects of both assembly and post-assembly conditions., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Phase transitions have an essential role in the assembly of nature's protein-based materials into hierarchically organized structures, yet many of the underlying mechanisms and interactions remain to be resolved. A central question for designing proteins for materials is how the protein architecture and sequence affects the nature of the phase transitions and resulting assembly. In this work, we produced 82 kDa (1×), 143 kDa (2×), and 204 kDa (3×) silk-mimicking proteins by taking advantage of protein ligation by SpyCatcher/Tag protein-peptide pair. We show that the three silk proteins all undergo a phase transition from homogeneous solution to assembly formation. In the assembly phase, a length- and concentration-dependent transition between two distinct assembly morphologies, one forming aggregates and another coacervates, exists. The coacervates showed properties that were dependent on the protein size. Computational modeling of the proteins by a bead-spring model supports the experimental results and provides us a possible mechanistic origin for the assembly transitions based on architectures and interactions.

This essay explores Kaila's interpretation of the special theory of relativity. Although the relevance of his work to logical empiricism is well-known, not much has been written on what Kaila calls the 'Einstein-Minkowski invariance theory'. Kaila's interpretation focuses on two salient features. First, he emphasizes the importance of the invariance of the spacetime interval. The general point about spacetime invariance has been known at least since Minkowski, yet Kaila applies his overall tripartite theory of invariances to space, time and spacetime in an original way. Second, Kaila provides a non-conventionalist argument for the isotropic speed of electromagnetic signals. The standard Einstein synchrony is not a mere convention but a part of a larger empirical theory. According to Kaila's holistic principle of testability, which stands in contrast to the theses of translatability and verification, different items in the theory cannot be sharply divided into conventional and empirical. Kaila's invariantism/non-conventionalism about relativity reflects an interesting case in the gradual transition from positivism to realism within the philosophy of science., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The effect of urea and ethanol additives on aqueous solutions of poly(styrenesulfonate) (PSS), poly(diallyldimethylammonium) (PDADMA), and their complexation interactions are examined here via molecular dynamics simulations, interconnected laser Doppler velocimetry, and quartz crystal microbalance with dissipation. It is found that urea and ethanol have significant, yet opposite influences on PSS and PDADMA solvation and interactions. Notably, ethanol is systematically depleted from solvating the charge groups but condenses at the hydrophobic backbone of PSS. As a consequence of the poorer solvation environment for the ionic groups, ethanol significantly increases the extent of counterion condensation. On the other hand, urea readily solvates both polyelectrolytes and replaces water in solvation. For PSS, urea causes disruption of the hydrogen bonding of the PSS headgroup with water. In PSS-PDADMA complexation, these differences influence changes in the binding configurations relative to the case of pure water. Specifically, added ethanol leads to loosening of the complex caused by the enhancement of counterion condensation; added urea pushes polyelectrolyte chains further apart because of the formation of a persistent solvation shell. In total, we find that the effects of urea and ethanol rise from changes in the microscopic-level solvation environment and conformation resulting from solvating water being replaced by the additive. The differences cannot be explained purely via considering relative permittivity and continuum level electrostatic screening. Taken together, the findings could bear significance in tuning polyelectrolyte materials' mechanical and swelling characteristics via solution additives., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The Nordic welfare state aims to offer universal healthcare and achieve good health, bar none. We discuss past and present moral blind spots in welfare state bioethics through reproductive justice and queer bioethics, particularly focusing on race and racism, based on ethnographic data from Finland. Globally portrayed as aspirational and mostly uninterrogated, it is crucial to have a thorough bioethical evaluation of a Nordic model informed by Black and queer perspectives. We have come to conceptualize the Finnish welfare state as haunted. We fear that the seemingly non-racial racial hygiene continues to haunt bioethics of the welfare state as structural racism. A key cause for this concern is the lack of racial awareness in public politics and the reluctance in discussing racism due to the national agenda of color-blindness. This crucially compounds to our findings that medical professionals prefer to think they operate on "purely medical" reasoning as opposed to nuanced ethical contemplation, the latter associated with "social issues" that allegedly cannot be resolved and are outside medical interest. We discuss how the bioethical aftermath of eugenics remains unresolved. Racist, classist, sexist, ableist, and cis- and heteronormative stratification of reproduction requires a nuanced moral compass for Nordic welfare state bioethics, not "strictly medical practice." We suggest queer bioethics as a moral theory for recalibrating this compass, joining forces with other justice movements to tackle racism in healthcare and further to interrogate racism, sexism, ableism and cis- and heteronormativity in bioethics., (© 2021 The Authors. Bioethics published by John Wiley & Sons Ltd.)

The aim of this study was to describe identified risk areas related to the medication administration process in acute care in order to develop a three-dimensional-game intervention. A secondary analysis was conducted using (1) observed medication administrations (n = 1058) and identified medication errors in 2012 (n = 235), (2) a systematic review including a meta-analysis of previous medication administration educational interventions (n = 14) from 2000 to 2015, (3) incident reports of medication administration errors (n = 1012) from 2013 to 2014, and (4) focus group interviews with RNs' (n = 20) views in 2015. A qualitative content analysis was used to identify risk areas, and the data were organized according to the following main themes: (1) factors related to patients (patient identification, patients' characteristics or symptoms, and patients' allergies and interactions); (2) factors related to medications (medication information, changes in medications, generic substitutes, new drugs, look-alike/sound-alike drugs, demanding drug treatments, medication preparation, and administration techniques); (3) factors related to staffing (workload, skills, interruptions and distractions, division of work, responsibility, attitudes, and guidelines); and (4) factors related to communication (flow of information, communication with the patients, and marking of medication information). Identified risk areas could be used to develop interventions with the aim of increasing the safety of medication administration and nurses' skills.

Background: Medication administration errors may contribute to patient mortality, thus additional understanding of such incidents is required., Objectives: To analyse medication administration errors reported in acute care resulting in death, to identify the drugs concerned, and to describe medication administration error characteristics (location of error, error type, patient's age) by drug group., Methods: Medication administration errors reported in acute care in 2007 ̶ 2016 (n = 517,384) were obtained from the National Reporting and Learning System for England and Wales. Incidents reported as resulting in death (n = 229) were analysed. Drugs were classified by two researchers using the British National Formulary. Drug categories were described by medication administration errors' year, location, patient age, and error category based on the incidents' original classification., Results: Errors were most often reported on wards (66.4%, n = 152), and in patients aged over 75 years (41.5%, n = 95). The most common error category was omitted medicine or ingredient (31.4%, n = 72); most common drug groups were cardiovascular (20.1%, n = 46) and nervous system (10.0%, n = 23). Most errors in patients under 12 years concerned drugs to treat infection; cardiovascular drugs were most common among other age groups., Conclusions: In order to prevent these most serious of medication administration errors, interventions should focus on avoiding dose omissions, and administration of drugs for patients over 75 years old, as well as safe administration of parenteral anticoagulants and antibacterial drugs., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Lung fluid clearance is essential for successful postnatal pulmonary adaptation. The epithelial sodium channel (ENaC) and Na-K-ATPase, induced by serum- and glucocorticoid-inducible kinase 1 (SGK1) as well as aquaporins (AQP), represent key players in the switch from fetal lung fluid secretion to absorption and in early postnatal lung fluid balance. Birth stress, including a surge in catecholamines, promotes pulmonary adaptation, likely through the augmentation of epithelial sodium reabsorption., Objectives: We sought to determine the changes in the airway gene expression of molecules vital to epithelial sodium transport during early pulmonary adaptation, and the association with birth stress reflected in the norepinephrine concentration in the cord blood in humans., Methods: We included 70 term newborns: 28 born via vaginal delivery and 42 via elective cesarean section. We determined the norepinephrine concentrations in the cord blood using tandem mass spectrometry and collected nasal epithelial cell samples at 2 min, 1 h, and 24 h postnatally to quantify ENaC, Na-K-ATPase, AQP5, and SGK1 mRNAs using RT-PCR., Results: The molecular gene expression involved in airway epithelium sodium transport changed markedly within the first hour postnatally. Newborns born via elective cesarean section exhibited a lower expression of ENaC, Na-K-ATPase, and SGK1. Significant correlations existed between the expressions of ENaC, Na-K-ATPase, and SGK1, and the concentration of norepinephrine in the cord blood., Conclusions: The association of ENaC, Na-K-ATPase, and SGK1 expression with the cord blood norepinephrine concentration points to the importance of birth stress in promoting lung fluid clearance during early postnatal pulmonary adaptation., (© 2019 Wiley Periodicals, Inc.)

Dissolution of elemental gold in organic solutions is a contemporary approach to lower the environmental burden associated with gold recycling. Herein, we describe fundamental studies on a highly efficient method for the dissolution of elemental Au that is based on DMF solutions containing pyridine-4-thiol (4-PSH) as a reactive ligand and hydrogen peroxide as an oxidant. Dissolution of Au proceeds through several elementary steps: isomerization of 4-PSH to pyridine-4-thione (4-PS), coordination with Au 0 , and then oxidation of the Au 0 thione species to Au I simultaneously with oxidation of free pyridine thione to elemental sulfur and further to sulfuric acid. The final dissolution product is a Au I complex bearing two 4-PS ligands and SO 4 2- as a counterion. The ligand is crucial as it assists the oxidation process and stabilizes and solubilizes the formed Au cations., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

One of the crucial steps in the life cycle of angiosperms is the development of carpels. They are the most complex plant organs, harbor the seeds, and, after fertilization, develop into fruits and are thus an important ecological and economic trait. CRABS CLAW (CRC), a YABBY protein and putative transcription factor, is one of the major carpel developmental regulators in A. thaliana that includes a C2C2 zinc finger and a domain with similarities to an HMG box. CRC is involved in the regulation of processes such as carpel fusion and growth, floral meristem termination, and nectary formation. While its genetic interactions with other carpel development regulators are well described, its biochemical properties and molecular way of action remain unclear. We combined Bimolecular Fluorescence Complementation, Yeast Two-Hybrid, and Yeast One-Hybrid analyzes to shed light on the molecular biology of CRC. Our results showed that CRC dimerizes, also with other YABBY proteins, via the YABBY domain, and that its DNA binding is mainly cooperative and is mediated by the YABBY domain. Further, we identified that CRC is involved in floral meristem termination via transcriptional repression while it acts as a transcriptional activator in nectary development and carpel fusion and growth control. This work increases our understanding on how YABBY transcription factors interact with other proteins and how they regulate their targets.

Classical electromagnetism and quantum mechanics are both central to the modern understanding of the physical world and its ongoing technological development. Quantum simulations of electromagnetic forces have the potential to provide information about materials and systems that do not have conveniently solvable theoretical descriptions, such as those related to quantum Hall physics, or that have not been physically observed, such as magnetic monopoles. However, quantum simulations that simultaneously implement all of the principal features of classical electromagnetism have thus far proved elusive. We experimentally realize a simulation in which a charged quantum particle interacts with the knotted electromagnetic fields peculiar to a topological model of ball lightning. These phenomena are induced by precise spatiotemporal control of the spin field of an atomic Bose-Einstein condensate, simultaneously creating a Shankar skyrmion-a topological excitation that was theoretically predicted four decades ago but never before observed experimentally. Our results reveal the versatile capabilities of synthetic electromagnetism and provide the first experimental images of topological three-dimensional skyrmions in a quantum system.

Vitamin D is a steroid hormone precursor that is associated with a range of human traits and diseases. Previous GWAS of serum 25-hydroxyvitamin D concentrations have identified four genome-wide significant loci (GC, NADSYN1/DHCR7, CYP2R1, CYP24A1). In this study, we expand the previous SUNLIGHT Consortium GWAS discovery sample size from 16,125 to 79,366 (all European descent). This larger GWAS yields two additional loci harboring genome-wide significant variants (P = 4.7×10 -9 at rs8018720 in SEC23A, and P = 1.9×10 -14 at rs10745742 in AMDHD1). The overall estimate of heritability of 25-hydroxyvitamin D serum concentrations attributable to GWAS common SNPs is 7.5%, with statistically significant loci explaining 38% of this total. Further investigation identifies signal enrichment in immune and hematopoietic tissues, and clustering with autoimmune diseases in cell-type-specific analysis. Larger studies are required to identify additional common SNPs, and to explore the role of rare or structural variants and gene-gene interactions in the heritability of circulating 25-hydroxyvitamin D levels.

This paper presents a practical application of a technique that uses a vertical optical flow with a fisheye camera to generate dense point clouds from a single planimetric station. Accurate data can be extracted to enable the measurement of tree trunks or branches. The images that are collected with this technique can be oriented in photogrammetric software (using fisheye models) and used to generate dense point clouds, provided that some constraints on the camera positions are adopted. A set of images was captured in a forest plot in the experiments. Weighted geometric constraints were imposed in the photogrammetric software to calculate the image orientation, perform dense image matching, and accurately generate a 3D point cloud. The tree trunks in the scenes were reconstructed and mapped in a local reference system. The accuracy assessment was based on differences between measured and estimated trunk diameters at different heights. Trunk sections from an image-based point cloud were also compared to the corresponding sections that were extracted from a dense terrestrial laser scanning (TLS) point cloud. Cylindrical fitting of the trunk sections allowed the assessment of the accuracies of the trunk geometric shapes in both clouds. The average difference between the cylinders that were fitted to the photogrammetric cloud and those to the TLS cloud was less than 1 cm, which indicates the potential of the proposed technique. The point densities that were obtained with vertical optical scanning were 1/3 less than those that were obtained with TLS. However, the point density can be improved by using higher resolution cameras., Competing Interests: The authors declare no conflict of interest.

This paper distinguishes between two arguments based on measurement robustness and defends the epistemic value of robustness for the assessment of measurement reliability. I argue that the appeal to measurement robustness in the assessment of measurement is based on a different inferential pattern and is not exposed to the same objections as the no-coincidence argument which is commonly associated with the use of robustness to corroborate individual results. This investigation sheds light on the precise meaning of reliability that emerges from measurement assessment practice. In addition, by arguing that the measurement assessment robustness argument has similar characteristics across the physical, social and behavioural sciences, I defend the idea that there is continuity in the notion of measurement reliability across sciences., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Although 'unhealthy' diet is a well-known risk factor for non-communicable diseases, its relationship with socio-economic status (SES) has not been fully investigated. Moreover, the available research has largely been conducted in countries at high levels of human development. This is the first study to examine relationships among dietary patterns and SES of children from countries spanning a wide range of human development., Methods: This was a multinational cross-sectional study among 9-11 year-old children (n = 6808) from urban/peri-urban sites across 12 countries. Self-reported food frequency questionnaires were used to determine the children's dietary patterns. Principal Components Analysis was employed to create two component scores representing 'unhealthy' and 'healthy' dietary patterns. Multilevel models accounting for clustering at the school and site level were used to examine the relationships among dietary patterns and SES., Results: The mean age of participants in this study (53.7% girls) was 10.4 years. Largest proportions of total variance in dietary patterns occurred at the individual, site, and school levels (individual, school, site: 62.8%; 10.8%; 26.4% for unhealthy diet pattern (UDP) and 88.9%; 3.7%; 7.4%) for healthy diet pattern (HDP) respectively. There were significant negative 'unhealthy' diet-SES gradients in 7 countries and positive 'healthy' diet-SES gradients in 5. Within country diet-SES gradients did not significantly differ by HDI. Compared to participants in the highest SES groups, unhealthy diet pattern scores were significantly higher among those in the lowest within-country SES groups in 8 countries: odds ratios for Australia (2.69; 95% CI: 1.33-5.42), Canada (4.09; 95% CI: 2.02-8.27), Finland (2.82; 95% CI: 1.27-6.22), USA (4.31; 95% CI: 2.20-8.45), Portugal (2.09; 95% CI: 1.06-4.11), South Africa (2.77; 95% CI: 1.22-6.28), India (1.88; 95% CI: 1.12-3.15) and Kenya (3.35; 95% CI: 1.91-5.87)., Conclusions: This study provides evidence of diet-SES gradients across all levels of human development and that lower within-country SES is strongly related to unhealthy dietary patterns. Consistency in within-country diet-SES gradients suggest that interventions and public health strategies aimed at improving dietary patterns among children may be similarly employed globally. However, future studies should seek to replicate these findings in more representative samples extended to more rural representation.

Substance-abusing pregnant and parenting women are considered one of the most challenging, but important, target groups for developing early parenting interventions. Some valuable efforts to develop such interventions have been made in the organizational sector in Finland. However, there is a great need for new ways of work that would simultaneously concentrate in substance-abuse treatment and enhance parenting in public healthcare settings. The present article describes the background, content, and protocol of a new prenatal intervention developed for substance-abusing pregnant women in a hospital setting in public healthcare. The intervention includes two new elements and pathways aimed to enhance the mothers' curiosity toward her developing child and provide motivation to stay abstinent from substance use. The pathways are interactive ultrasound consultation and a new pregnancy diary, both using a parental mentalization focus. The intervention elements, experiences from running the intervention, evaluation protocol, and general characteristics of the study sample gained (n = 90) are described and discussed. Two case vignettes from the study sample are presented, and the applicability of this prenatal work with other groups and settings is considered., (© 2016 Michigan Association for Infant Mental Health.)

Postnatal mother-infant bonding refers to the early emotional bond between mothers and infants. Although some factors, such as maternal mental health, especially postnatal depression, have been considered in relation to mother-infant bonding, few studies have investigated the role of infant temperament traits in early bonding. In this study, the effects of maternal postnatal depressive and anxiety symptoms and infant temperament traits on mother-infant bonding were examined using both mother and father reports of infant temperament. Data for this study came from the first phase of the FinnBrain Birth Cohort Study (n=102, father reports n=62). After controlling for maternal symptoms of depression and anxiety, mother-reported infant positive emotionality, measured by infant smiling was related to better mother-infant bonding. In contrast, infant negative emotionality, measured by infant distress to limitations was related to lower quality of bonding. In regards to father-report infant temperament, only infant distress to limitations (i.e., frustration/anger) was associated with lower quality of mother-infant bonding. These findings underline the importance of infant temperament as one factor contributing to early parent-infant relationships, and counseling parents in understanding and caring for infants with different temperament traits., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Introduction: This study explored the effects of mothers' and fathers' prenatal and postnatal depressive symptoms and marital distress on breastfeeding initiation and exclusive breastfeeding (EBF) duration., Material and Methods: This was a prospective follow-up of a cohort sample of 873 families participating to an intensive follow-up cohort of longitudinal Steps to the Healthy Development and Well-being of Children study (The STEPS study) in Southwestern Finland. The depressive symptoms were evaluated by The Edinburgh Postpartum Depression Scale and marital distress by the Revised Dyadic Adjustment Scale at 20th gestational week and at 4 months postpartum. EBF was self-reported real-time and defined as an infant receiving no food or drink other than mother's breast milk since birth, except occasionally water., Results: Neither parents' prenatal depressive symptoms predicted breastfeeding initiation or EBF duration. The mothers' prenatal depressive symptoms, in turn, predicted their postnatal depressive symptoms, which were associated with shorter duration of EBF. The EBF duration was shortest amongst the mothers who had depressive symptoms both pre- and postnatally compared to mothers who had depressive symptoms only in either time point alone (M = 1.54, 2.06 and 2.04 months, respectively). Higher prenatal maternal marital distress was associated with longer EBF duration., Conclusions: The findings suggest that the continuity of maternal depressive symptoms throughout the perinatal period has adverse effect on EBF duration. Identification and treatment of mothers' depressive symptoms already during the prenatal period may improve breastfeeding practices. The finding of mothers' marital distress having positive impact on breastfeeding practices requires further investigation., (© 2016 Nordic Federation of Societies of Obstetrics and Gynecology.)

Aim: The aim of the present study was to describe the development of Families First, a new mentalization-based group intervention model for supporting early parenthood. The general aim of the intervention was to support well-functioning models of parenting and prevent transmission of negative parenting models over generations, and thus promote child development and overall family health., Background: In the Finnish society, great concern has aroused during the last decade regarding the well-being and mental health of children and adolescents. Increased number of divorces, poverty, substance abuse, and mental health problems among parents enhance the risk for child neglect and abuse. New effective, preventive, and health-promoting intervention tools are greatly needed to support families with young children. At present, the Families First intervention is being implemented in primary social and healthcare units all over Finland., Methods and Findings: This article will provide a theoretical understanding of the importance of parental mentalization for the development of the parent-child relationship and the development of the child as well as proposed mechanisms of actions in order to enhance mentalizing capacity. The cultural context will be described. The article will also provide a description of the scientific evaluation protocol of the intervention model. Finally, possible limitations and challenges of the intervention model are discussed.

The theme of phenomenology and quantum physics is here tackled by examining some basic interpretational issues in quantum physics. One key issue in quantum theory from the very beginning has been whether it is possible to provide a quantum ontology of particles in motion in the same way as in classical physics, or whether we are restricted to stay within a more limited view of quantum systems, in terms of complementary but mutually exclusive phenomena. In phenomenological terms we could describe the situation by saying that according to the usual interpretation of quantum theory (especially Niels Bohr's), quantum phenomena require a kind of epoché (i.e. a suspension of assumptions about reality at the quantum level). However, there are other interpretations (especially David Bohm's) that seem to re-establish the possibility of a mind-independent ontology at the quantum level. We will show that even such ontological interpretations contain novel, non-classical features, which require them to give a special role to "phenomena" or "appearances", a role not encountered in classical physics. We will conclude that while ontological interpretations of quantum theory are possible, quantum theory implies the need of a certain kind of epoché even for this type of interpretations. While different from the epoché connected to phenomenological description, the "quantum epoché" nevertheless points to a potentially interesting parallel between phenomenology and quantum philosophy., (Copyright © 2015. Published by Elsevier Ltd.)