Response to Hansen Wheat et al.: Additional analysis further supports the early emergence of cooperative communication in dogs compared to wolves raised with more human exposure.

Here, we address Hansen Wheat et al.'s commentary in this journal in response to Salomons et al. Current Biology, 31(14), 3137-3144.E11, (2021). We conduct additional analyses in response to Hansen Wheat et al.'s two main questions. First, we examine the claim that it was the move to a human home environment which enabled the dog puppies to outperform the wolf puppies in gesture comprehension tasks. We show that the youngest dog puppies who had not yet been individually placed in raisers' homes were still highly skilled, and outperformed similar-aged wolf puppies who had higher levels of human interaction. Second, we address the claim that willingness to approach a stranger can explain the difference between dog and wolf pups' ability to succeed in gesture comprehension tasks. We explain the various controls in the original study that render this explanation insufficient, and demonstrate via model comparison that the covariance of species and temperament also make this parsing impossible. Overall, our additional analyses and considerations support the domestication hypothesis as laid out by Salomons et al. Current Biology, 31(14), 3137-3144.E11, (2021).

Observation of Microheterogeneity in Highly Concentrated Nonaqueous Electrolyte Solutions.

The development of models to describe structure and dynamics of nonaqueous electrolyte solutions is challenging, and experimental observations are needed to form a foundation. Here, neutron scattering is used to probe molecular dynamics in nonaqueous organic electrolytes. Two solutions were compared: one contained symmetrical electrolyte molecules prone to crystallize, and one contained desymmetrized electrolyte molecules preferring disordered states. For the latter, calorimetry and neutron data show that a disordered fluid persists to very low temperatures at high concentrations. Upon heating, localized cold crystallization occurs, leading to burst nucleation of microcrystalline solids within fluid phases. Our findings indicate molecular clustering and point to solvation inhomogeneities and molecular crowding in these concentrated fluids.

Global Sensitivity Analysis To Characterize Operational Limits and Prioritize Performance Goals of Capacitive Deionization Technologies.

Capacitive deionization (CDI) technologies couple electronic and ionic charge storage, enabling improved thermodynamic efficiency of brackish desalination by recovering energy released during discharge. However, insight into CDI has been limited by discrete experimental observations at low desalination depths (Δ c, typically reducing influent salinity by 10 mM or less). In this study, the performance and sensitivity of three common CDI configurations [standard CDI, membrane CDI (MCDI), and flowable electrode CDI (FCDI)] were evaluated across the operational and material design landscape by varying eight common input parameters (electrode thickness, influent concentration, current density, electrode flow rate, specific capacitance, contact resistance, porosity, and fixed charge). All combinations of designs were evaluated for two influent concentrations with a calibrated and validated one-dimensional (1-D) porous electrode model. Sensitivity analyses were carried out via Monte Carlo and Morris methods, focusing on six performance metrics. Across all performance metrics, high sensitivity was observed to input parameters which impact cycle length (current, resistance, and capacitance). Simulations demonstrated the importance of maintaining both charge and round-trip efficiencies, which limit the performance of CDI and FCDI, respectively. Accounting for energy recovery, only MCDI was capable of operating at thermodynamic efficiencies similar to reverse osmosis.

Linking capacity loss and retention of nickel hexacyanoferrate to a two-site intercalation mechanism for aqueous Mg2+ and Ca2+ ions.

Prussian blue analogues (PBAs) are promising cation intercalation materials for electrochemical desalination and energy storage applications. Here, we investigate the mechanism of capacity fade and degradation of nickel hexacyanoferrate (NiHCFe) during galvanostatic cycling in aqueous electrolytes that are rich in either Mg2+ or Ca2+. We combine experimental characterization, first principles electronic structure calculations, statistical mechanics and lattice-percolation modeling of electron transfer to elucidate the mechanisms responsible for the degradation of NiHCFe and its partial retention of capacity. Electrochemical characterization of porous NiHCFe electrodes suggests a two-site intercalation mechanism, while spectroscopy reveals the presence of Ni2+ and Fe(CN)63- ions in the electrolyte post cycling in Mg2+(aq). Using simple coprecipitation reactions, we show that Mg2+ and Ni2+ can coexist in the lattice framework, forming stable PBAs. Galvanostatic cycling of these PBAs shows that the presence of Mg2+ in the lattice framework results in the dissolution of Mg1.5FeIII(CN)6 in water during oxidation. We propose that Mg2+ can partially substitute Ni2+ ions in the lattice framework during galvanostatic cycling, displacing the substituted Ni2+ ions into interstitial sites. Based on differential capacitance analysis we show that Mg2+ intercalates into interstitial sites at ∼0.45 V vs. Ag/AgCl and it displaces Ni2+ in the lattice framework at ∼0.05 V vs. Ag/AgCl. Substitution of Ni2+ leads to Fe(CN)63- and Ni2+ ions being removed into the electrolyte during oxidation. Using first principles density functional theory (DFT) calculations combined with a statistical mechanics model, we verify the thermodynamic feasibility of the proposed reaction mechanism and predict the fraction of Ni2+ ions being substituted by Mg2+ during intercalation. Further, analysis of the electron density distribution and local density of states indicates that Mg2+ ions can act as insulating defects in the lattice framework that render certain Fe ions electrically inactive and likely contribute to capacity fade along with dissolution of Fe(CN)63-.

Nanopore occlusion: A biophysical mechanism for bipolar cancellation in cell membranes.

Extraordinarily large but short electric field pulses are reported by many experiments to cause bipolar cancellation (BPC). This unusual cell response occurs if a first pulse is followed by a second pulse with opposite polarity. Possibly universal, BPC presently lacks a mechanistic explanation. Multiple versions of the "standard model" of cell electroporation (EP) fail to account for BPC. Here we show, for the first time, how an extension of the standard model can account for a key experimental observation that essentially defines BPC: the amount of a tracer that enters a cell, and how tracer influx can be decreased by the second part of a bipolar pulse. The extended model can also account for the recovery of BPC wherein the extent of BPC is diminished if the spacing between the first and second pulses is increased. Our approach is reverse engineering, meaning that we identify and introduce an additional biophysical mechanism that allows pore transport to change. We hypothesize that occluding molecules from outside the membrane enter or relocate within a pore. Significantly, the additional mechanism is fundamental and general, involving a combination of partitioning and hindrance. Molecules near the membrane can enter pores to block transport of tracer molecules while still passing small ions (charge number ±1) that govern electrical behavior. Our extension of the standard model accounts for key BPC behavior.

Versatile technique for assessing thickness of 2D layered materials by XPS.

X-ray photoelectron spectroscopy (XPS) has been utilized as a versatile method for thickness characterization of various two-dimensional (2D) films. Accurate thickness can be measured simultaneously while acquiring XPS data for chemical characterization of 2D films having thickness up to approximately 10 nm. For validating the developed technique, thicknesses of few-layer graphene (FLG), MoS2 and amorphous boron nitride (a-BN) layer, produced by microwave plasma chemical vapor deposition (MPCVD), plasma enhanced chemical vapor deposition (PECVD), and pulsed laser deposition (PLD) respectively, were accurately measured. The intensity ratio between photoemission peaks recorded for the films (C 1s, Mo 3d, B 1s) and the substrates (Cu 2p, Al 2p, Si 2p) is the primary input parameter for thickness calculation, in addition to the atomic densities of the substrate and the film, and the corresponding electron attenuation length (EAL). The XPS data was used with a proposed model for thickness calculations, which was verified by cross-sectional transmission electron microscope (TEM) measurement of thickness for all the films. The XPS method determines thickness values averaged over an analysis area which is orders of magnitude larger than the typical area in cross-sectional TEM imaging, hence provides an advanced approach for thickness measurement over large areas of 2D materials. The study confirms that the versatile XPS method allows rapid and reliable assessment of the 2D material thickness and this method can facilitate in tailoring growth conditions for producing very thin 2D materials effectively over a large area. Furthermore, the XPS measurement for a typical 2D material is non-destructive and does not require special sample preparation. Therefore, after XPS analysis, exactly the same sample can undergo further processing or utilization.

Polysulfide flow batteries enabled by percolating nanoscale conductor networks.

A new approach to flow battery design is demonstrated wherein diffusion-limited aggregation of nanoscale conductor particles at ∼1 vol % concentration is used to impart mixed electronic-ionic conductivity to redox solutions, forming flow electrodes with embedded current collector networks that self-heal after shear. Lithium polysulfide flow cathodes of this architecture exhibit electrochemical activity that is distributed throughout the volume of flow electrodes rather than being confined to surfaces of stationary current collectors. The nanoscale network architecture enables cycling of polysulfide solutions deep into precipitation regimes that historically have shown poor capacity utilization and reversibility and may thereby enable new flow battery designs of higher energy density and lower system cost. Lithium polysulfide half-flow cells operating in both continuous and intermittent flow mode are demonstrated for the first time.

Basic features of a cell electroporation model: illustrative behavior for two very different pulses.

Science increasingly involves complex modeling. Here we describe a model for cell electroporation in which membrane properties are dynamically modified by poration. Spatial scales range from cell membrane thickness (5 nm) to a typical mammalian cell radius (10 µm), and can be used with idealized and experimental pulse waveforms. The model consists of traditional passive components and additional active components representing nonequilibrium processes. Model responses include measurable quantities: transmembrane voltage, membrane electrical conductance, and solute transport rates and amounts for the representative "long" and "short" pulses. The long pulse--1.5 kV/cm, 100 µs--evolves two pore subpopulations with a valley at ~5 nm, which separates the subpopulations that have peaks at ~1.5 and ~12 nm radius. Such pulses are widely used in biological research, biotechnology, and medicine, including cancer therapy by drug delivery and nonthermal physical tumor ablation by causing necrosis. The short pulse--40 kV/cm, 10 ns--creates 80-fold more pores, all small (<3 nm; ~1 nm peak). These nanosecond pulses ablate tumors by apoptosis. We demonstrate the model's responses by illustrative electrical and poration behavior, and transport of calcein and propidium. We then identify extensions for expanding modeling capability. Structure-function results from MD can allow extrapolations that bring response specificity to cell membranes based on their lipid composition. After a pulse, changes in pore energy landscape can be included over seconds to minutes, by mechanisms such as cell swelling and pulse-induced chemical reactions that slowly alter pore behavior.

Phage cluster relationships identified through single gene analysis.

BACKGROUND: Phylogenetic comparison of bacteriophages requires whole genome approaches such as dotplot analysis, genome pairwise maps, and gene content analysis. Currently mycobacteriophages, a highly studied phage group, are categorized into related clusters based on the comparative analysis of whole genome sequences. With the recent explosion of phage isolation, a simple method for phage cluster prediction would facilitate analysis of crude or complex samples without whole genome isolation and sequencing. The hypothesis of this study was that mycobacteriophage-cluster prediction is possible using comparison of a single, ubiquitous, semi-conserved gene. Tape Measure Protein (TMP) was selected to test the hypothesis because it is typically the longest gene in mycobacteriophage genomes and because regions within the TMP gene are conserved. RESULTS: A single gene, TMP, identified the known Mycobacteriophage clusters and subclusters using a Gepard dotplot comparison or a phylogenetic tree constructed from global alignment and maximum likelihood comparisons. Gepard analysis of 247 mycobacteriophage TMP sequences appropriately recovered 98.8% of the subcluster assignments that were made by whole-genome comparison. Subcluster-specific primers within TMP allow for PCR determination of the mycobacteriophage subcluster from DNA samples. Using the single-gene comparison approach for siphovirus coliphages, phage groupings by TMP comparison reflected relationships observed in a whole genome dotplot comparison and confirm the potential utility of this approach to another widely studied group of phages. CONCLUSIONS: TMP sequence comparison and PCR results support the hypothesis that a single gene can be used for distinguishing phage cluster and subcluster assignments. TMP single-gene analysis can quickly and accurately aid in mycobacteriophage classification.

Sub-surface imaging of carbon nanotube-polymer composites using dynamic AFM methods.

High-resolution sub-surface imaging of carbon nanotube (CNT) networks within polymer nanocomposites is demonstrated through electrical characterization techniques based on dynamic atomic force microscopy (AFM). We compare three techniques implemented in the single-pass configuration: DC-biased amplitude modulated AFM (AM-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) in terms of the physics of sub-surface image formation and experimental robustness. The methods were applied to study the dispersion of sub-surface networks of single-walled nanotubes (SWNTs) in a polyimide (PI) matrix. We conclude that among these methods, the KPFM channel, which measures the capacitance gradient (∂C/∂d) at the second harmonic of electrical excitation, is the best channel to obtain high-contrast images of the CNT network embedded in the polymer matrix, without the influence of surface conditions. Additionally, we propose an analysis of the ∂C/∂d images as a tool to characterize the dispersion and connectivity of the CNTs. Through the analysis we demonstrate that these AFM-based sub-surface methods probe sufficiently deep within the SWNT composites, to resolve clustered networks that likely play a role in conductivity percolation. This opens up the possibility of dynamic AFM-based characterization of sub-surface dispersion and connectivity in nanostructured composites, two critical parameters for nanocomposite applications in sensors and energy storage devices.

Aqueous semi-solid flow cell: demonstration and analysis.

An aqueous Li-ion flow cell using suspension-based flow electrodes based on the LiTi2(PO4)3-LiFePO4 couple is demonstrated. Unlike conventional flow batteries, the semi-solid approach utilizes fluid electrodes that are electronically conductive. A model of simultaneous advection and electrochemical transport is developed and used to separate flow-induced losses from those due to underlying side reactions. The importance of plug flow to achieving high energy efficiency in flow batteries utilizing highly non-Newtonian flow electrodes is emphasized.

Optogenetic inhibition of cocaine seeking in rats.

Inhibitory optogenetics was used to examine the roles of the prelimbic cortex (PL), the nucleus accumbens core (NAcore) and the PL projections to the NAcore in the reinstatement of cocaine seeking. Rats were microinjected into the PL or NAcore with an adeno-associated virus containing halorhodopsin or archaerhodopsin. After 12 days of cocaine self-administration, followed by extinction training, animals underwent reinstatement testing along with the presence/absence of optically induced inhibition via laser light. Bilateral optical inhibition of the PL, NAcore or the PL fibers in the NAcore inhibited the reinstatement of cocaine seeking.

Neural circuit competition in cocaine-seeking: roles of the infralimbic cortex and nucleus accumbens shell.

Following cocaine self-administration and extinction training, activity in the infralimbic cortex (IL) suppresses cocaine-seeking behavior. IL inactivation induces cocaine-seeking whereas activation suppresses cocaine-reinstated drug-seeking. We asked how the suppression of cocaine-seeking induced by IL activation integrates with the circuitry promoting reinstated cocaine-seeking. Following cocaine self-administration and extinction training, rats underwent cue-induced reinstatement. In order to activate IL projections, microinjections of PEPA, a positive allosteric modulator of AMPA receptors, were made into the IL in combination with microinjections into a variety of nuclei known to regulate cocaine-seeking. Intra-IL PEPA administration suppressed cue-induced reinstatement without affecting locomotor activity. The suppression of cocaine-seeking was reversed by activating dopamine neurons in the ventral tegmental area with microinjections of the µ-opioid receptor agonist DAMGO, and was partially reversed by dopamine microinjections into the prelimbic cortex or basolateral amygdala. Previous evidence suggests that the nucleus accumbens shell both promotes and suppresses cocaine-seeking. The suppression of cue-induced cocaine seeking by PEPA in the IL was reversed by intra-shell microinjections of either dopamine or the AMPA receptor antagonist CNQX, suggesting that the accumbens shell bidirectionally regulates cocaine-seeking depending on whether dopamine input is mimicked or glutamate input is inhibited. Together, these findings indicate that the IL acts 'upstream' from structures promoting cocaine-seeking, including from the mesolimbic dopamine projections to the prelimbic cortex and basolateral amygdala, and that the accumbens shell may be a crucial point of integration between the circuits that promote (ventral tegmental area) and inhibit (IL) reinstated cocaine-seeking.

Columnar order in jammed LiFePO4 cathodes: ion transport catastrophe and its mitigation.

The high-rate, high-capacity potential of LiFePO4-based lithium-ion battery cathodes has motivated numerous experimental and theoretical studies aiming to realize such performance through nano-sizing, tailoring of particle shape through synthesis conditions, and doping. Here, a granular mechanics study of microstructures formed by dense jammed packings of experimentally and theoretically inspired LiFePO4 particle shapes is presented. A strong dependence of the resultant packing structures on particle shapes is observed, in which columnar structures aligned with the [010] direction inhibit diffusion along [010] in anisotropic LiFePO4. Transport limitations are induced by [010] columnar order and lead to catastrophic performance degradation in anisotropic LiFePO4 electrodes. Further, judicious mixing of nanoplatelets with additive nanoparticles can frustrate columnar ordering and thereby enhance the rate capability of LiFePO4 electrodes by nearly an order of magnitude.

Efficient, Selective Sodium and Lithium Removal by Faradaic Deionization Using Symmetric Sodium Titanium Vanadium Phosphate Intercalation Electrodes.

NASICON (sodium superionic conductor) materials are promising host compounds for the reversible capture of Na+ ions, finding prior application in batteries as solid-state electrolytes and cathodes/anodes. Given their affinity for Na+ ions, these materials can be used in Faradaic deionization (FDI) for the selective removal of sodium over other competing ions. Here, we investigate the selective removal of sodium over other alkali and alkaline-earth metal cations from aqueous electrolytes when using a NASICON-based mixed Ti-V phase as an intercalation electrode, namely, sodium titanium vanadium phosphate (NTVP). Galvanostatic cycling experiments in three-electrode cells with electrolytes containing Na+, K+, Mg2+, Ca2+, and Li+ reveal that only Na+ and Li+ can intercalate into the NTVP crystal structure, while other cations show capacitive response, leading to a material-intrinsic selectivity factor of 56 for Na+ over K+, Mg2+, and Ca2+. Furthermore, electrochemical titration experiments together with modeling show that an intercalation mechanism with a limited miscibility gap for Na+ in NTVP mitigates the state-of-charge gradients to which phase-separating intercalation electrodes are prone when operated under electrolyte flow. NTVP electrodes are then incorporated into an FDI cell with automated fluid recirculation to demonstrate up to 94% removal of sodium in streams with competing alkali/alkaline-earth cations with 10-fold higher concentration, showing process selectivity factors of 3-6 for Na+ over cations other than Li+. Decreasing the current density can improve selectivity up to 25% and reduce energy consumption by as much as ∼50%, depending on the competing ion. The results also indicate the utility of NTVP for selective lithium recovery.

Isolation of circulating tumor cells.

Circulating tumor cells (CTCs) enter the vasculature from solid tumors and disseminate widely to initiate metastases. Mining the metastatic-enriched molecular signatures of CTCs before, during, and after treatment holds unique potential in personalized oncology. Their extreme rarity, however, requires isolation from large blood volumes at high yield and purity, yet they overlap leukocytes in size and other biophysical properties. Additionally, many CTCs lack EpCAM that underlies much of affinity-based capture, complicating their separation from blood. Here, we provide a comprehensive introduction of CTC isolation technology, by analyzing key separation modes and integrated isolation strategies. Attention is focused on recent progress in microfluidics, where an accelerating evolution is occurring in high-throughput sorting of cells along multiple dimensions.

Transmembrane molecular transport during versus after extremely large, nanosecond electric pulses.

Recently there has been intense and growing interest in the non-thermal biological effects of nanosecond electric pulses, particularly apoptosis induction. These effects have been hypothesized to result from the widespread creation of small, lipidic pores in the plasma and organelle membranes of cells (supra-electroporation) and, more specifically, ionic and molecular transport through these pores. Here we show that transport occurs overwhelmingly after pulsing. First, we show that the electrical drift distance for typical charged solutes during nanosecond pulses (up to 100 ns), even those with very large magnitudes (up to 10 MV/m), ranges from only a fraction of the membrane thickness (5 nm) to several membrane thicknesses. This is much smaller than the diameter of a typical cell (∼16 µm), which implies that molecular drift transport during nanosecond pulses is necessarily minimal. This implication is not dependent on assumptions about pore density or the molecular flux through pores. Second, we show that molecular transport resulting from post-pulse diffusion through minimum-size pores is orders of magnitude larger than electrical drift-driven transport during nanosecond pulses. While field-assisted charge entry and the magnitude of flux favor transport during nanosecond pulses, these effects are too small to overcome the orders of magnitude more time available for post-pulse transport. Therefore, the basic conclusion that essentially all transmembrane molecular transport occurs post-pulse holds across the plausible range of relevant parameters. Our analysis shows that a primary direct consequence of nanosecond electric pulses is the creation (or maintenance) of large populations of small pores in cell membranes that govern post-pulse transmembrane transport of small ions and molecules.

Low porosity, high areal-capacity Prussian blue analogue electrodes enhance salt removal and thermodynamic efficiency in symmetric Faradaic deionization with automated fluid control.

Prussian blue analogues (PBAs) show great potential for low-energy Faradaic deionization (FDI) with reversible Na-ion capacity approaching 5 M in the solid-state. However, past continuous-flow demonstrations using PBAs in FDI were unable to desalinate brackish water to potable levels using single-pass architectures. Here, we show that recirculation of effluent from a symmetric cation intercalation desalination cell into brine/diluate reservoirs enables salt removal exceeding 80% at thermodynamic efficiency as high as 80% when cycled with 100 mM NaCl influent and when controlled by a low-volume, automated fluid circuit. This exceptional performance is achieved using a novel heated, alkaline wet phase inversion process that modulates colloidal forces to increase carbon black aggregation within electrode slurries to solidify crack-free, high areal-capacity PBA electrodes that are calendered to minimize cell impedance and electrode porosity. The results obtained demonstrate the need for co-design of auxiliary fluid-control systems together with electrode materials to advance FDI beyond brackish salinity.

Cooperative Communication with Humans Evolved to Emerge Early in Domestic Dogs.

Although we know that dogs evolved from wolves, it remains unclear how domestication affected dog cognition. One hypothesis suggests dog domestication altered social maturation by a process of selecting for an attraction to humans.1-3 Under this account, dogs became more flexible in using inherited skills to cooperatively communicate with a new social partner that was previously feared and expressed these unusual social skills early in development.4-6 Here, we comparedog (n = 44) and wolf (n = 37) puppies, 5-18 weeks old, on a battery of temperament and cognition tasks. We find that dog puppies are more attracted to humans, read human gestures more skillfully, and make more eye contact with humans than wolf puppies. The two species are similarly attracted to familiar objects and perform similarly on non-social measures of memory and inhibitory control. These results are consistent with the idea that domestication enhanced the cooperative-communicative abilities of dogs as selection for attraction to humans altered social maturation.

Mechanisms for the intracellular manipulation of organelles by conventional electroporation.

Conventional electroporation (EP) changes both the conductance and molecular permeability of the plasma membrane (PM) of cells and is a standard method for delivering both biologically active and probe molecules of a wide range of sizes into cells. However, the underlying mechanisms at the molecular and cellular levels remain controversial. Here we introduce a mathematical cell model that contains representative organelles (nucleus, endoplasmic reticulum, mitochondria) and includes a dynamic EP model, which describes formation, expansion, contraction, and destruction for the plasma and all organelle membranes. We show that conventional EP provides transient electrical pathways into the cell, sufficient to create significant intracellular fields. This emerging intracellular electrical field is a secondary effect due to EP and can cause transmembrane voltages at the organelles, which are large enough and long enough to gate organelle channels, and even sufficient, at some field strengths, for the poration of organelle membranes. This suggests an alternative to nanosecond pulsed electric fields for intracellular manipulations.