Reconfiguring the Hydrogen Networks of Aqueous Electrolyte to Stabilize Iron Hexacyanoferrate for High-Voltage Decoupled Cell.

Prussian blue analogs (PBAs) as insertion-type cathodes have attracted significant attention in various aqueous batteries to accommodate metal or non-metal ions while suffering from serious dissolution and consequent inferior lifespan. Herein, we reveal that the dissolution of PBAs primarily originates from the locally elevated pH of electrolytes that are caused by proton co-insertion during discharge. To address this issue, a water-locking electrolyte (WLE) has been strategically implemented, which interrupts the generation and Grotthuss diffusion of protons by breaking the well-connected hydrogen bonding network in aqueous electrolytes. As a result, the WLE enables the iron hexacyanoferrate to endure over 1000 cycles at a 1C rate and supports a high-voltage decoupled cell with an average voltage of 1.95 V. These findings provide insights for mitigating dissolution problems in electrode materials, thereby enhancing the viability and performance of aqueous batteries.

Spatial Structure Design of Thioether-Linked Naphthoquinone Cathodes for High-Performance Aqueous Zinc-Organic Batteries.

Organic electrode materials (OEMs) have gathered extensive attention for aqueous zinc-ion batteries (AZIBs) due to their structural diversity and molecular designability. However, the reported research mainly focuses on the design of the planar configuration of OEMs and does not take into account the important influence of the spatial structure on the electrochemical properties, which seriously hamper the further performance liberation of OEMs. Herein, this work has designed a series of thioether-linked naphthoquinone-derived isomers with tunable spatial structures and applied them as the cathodes in AZIBs. The incomplete conjugated structure of the elaborately engineered isomers can guarantee the independence of the redox reaction of active groups, which contributes to the full utilization of active sites and high redox reversibility. In addition, the position isomerization of naphthoquinones on the benzene rings changes the zincophilic activity and redox kinetics of the isomers, signifying the importance of spatial structure on the electrochemical performance. As a result, the 2,2'-(1,4-phenylenedithio) bis(1,4-naphthoquinone) (p-PNQ) with the smallest steric hindrance and the most independent redox of active sites exhibits a high specific capacity (279 mAh g-1 ), an outstanding rate capability (167 mAh g-1 at 100 A g-1 ), and a long-term cycling lifetime (over 2800 h at 0.05 A g-1 ).

Effects of polymer polarity on the interface interaction of polymer/liquid metal composites.

Soft polymer/liquid metal (LM) composites have attracted considerable interest in flexible electronic energy fields. Interface interaction is a key issue that limits the improvement of their electrical performances and energy density. This paper investigates the influence of the polymer polarity on the interface interaction of composites. Four polymer matrixes-polypropylene (PP), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), and poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) were used. It was found that the order of interaction obeyed the order of the polymer polarity: PP/LM < PET/LM < PVDF/LM ≤ (P(VDF-TrFE-CFE))/LM. The increase in polymer polarity significantly promotes the dipole-dipole interaction between polar groups of polymers and the oxide shell of the LM. The best high-polarity PVDF/LM composites display good interface interaction to suppress the dielectric loss, facilitating the PVDF/LM films to exhibit increased capacitive storage density (+44%, 1.68 J cm-3) without degrading the energy efficiency (80%). Our findings will guide researchers to design and choose matrix materials for achieving more improved performance of LM devices.

In Situ Electrochemical Activation of Hydroxyl Polymer Cathode for High-Performance Aqueous Zinc-Organic Batteries.

The slow reaction kinetics and structural instability of organic electrode materials limit the further performance improvement of aqueous zinc-organic batteries. Herein, we have synthesized a Z-folded hydroxyl polymer polytetrafluorohydroquinone (PTFHQ) with inert hydroxyl groups that could be partially oxidized to the active carbonyl groups through the in situ activation process and then undertake the storage/release of Zn2+ . In the activated PTFHQ, the hydroxyl groups and S atoms enlarge the electronegativity region near the electrochemically active carbonyl groups, enhancing their electrochemical activity. Simultaneously, the residual hydroxyl groups could act as hydrophilic groups to enhance the electrolyte wettability while ensuring the stability of the polymer chain in the electrolyte. Also, the Z-folded structure of PTFHQ plays an important role in reversible binding with Zn2+ and fast ion diffusion. All these benefits make the activated PTFHQ exhibit a high specific capacity of 215 mAh g-1 at 0.1 A g-1 , over 3400 stable cycles with a capacity retention of 92 %, and an outstanding rate capability of 196 mAh g-1 at 20 A g-1 .

Cortical Tracking of Continuous Speech Under Bimodal Divided Attention.

Speech processing often occurs amid competing inputs from other modalities, for example, listening to the radio while driving. We examined the extent to which dividing attention between auditory and visual modalities (bimodal divided attention) impacts neural processing of natural continuous speech from acoustic to linguistic levels of representation. We recorded electroencephalographic (EEG) responses when human participants performed a challenging primary visual task, imposing low or high cognitive load while listening to audiobook stories as a secondary task. The two dual-task conditions were contrasted with an auditory single-task condition in which participants attended to stories while ignoring visual stimuli. Behaviorally, the high load dual-task condition was associated with lower speech comprehension accuracy relative to the other two conditions. We fitted multivariate temporal response function encoding models to predict EEG responses from acoustic and linguistic speech features at different representation levels, including auditory spectrograms and information-theoretic models of sublexical-, word-form-, and sentence-level representations. Neural tracking of most acoustic and linguistic features remained unchanged with increasing dual-task load, despite unambiguous behavioral and neural evidence of the high load dual-task condition being more demanding. Compared to the auditory single-task condition, dual-task conditions selectively reduced neural tracking of only some acoustic and linguistic features, mainly at latencies >200 ms, while earlier latencies were surprisingly unaffected. These findings indicate that behavioral effects of bimodal divided attention on continuous speech processing occur not because of impaired early sensory representations but likely at later cognitive processing stages. Crossmodal attention-related mechanisms may not be uniform across different speech processing levels.

A dendrite-free and anticaustic Zn anode enabled by high current-induced reconstruction of the electrical double layer.

Aqueous Zn-based batteries deliver thousands of cycles at high rates but poor recyclability at low rates. Herein, we reveal that this illogical phenomenon is attributed to the reconstructed electrode/electrolyte interface at high rates, wherein the condensed electrical double layer (EDL) and the tightly absorbed Zn2+ ions on the Zn electrode surface afford compact and corrosion-resistant Zn deposits.

High-Energy and Long-Lived Zn-MnO2 Battery Enabled by a Hydrophobic-Ion-Conducting Membrane.

Alkaline Zn-MnO2 batteries feature high security, low cost, and environmental friendliness while suffering from severe electrochemical irreversibility for both the Zn anode and MnO2 cathode. Although neutral electrolytes are supposed to improve the reversibility of the Zn anode, the MnO2 cathode indeed experiences a capacity degradation caused by the Jahn-Teller effect of the Mn3+ ion, thus shortening the lifespan of the neutral Zn-MnO2 batteries. Theoretically, the MnO2 cathode undergoes a highly reversible two-electron redox reaction of the MnO2/Mn2+ couple in strongly acidic electrolytes. However, acidic electrolytes would inevitably accelerate the corrosion of the Zn anode, making long-lived acidic Zn-MnO2 batteries impossible. Herein, to overcome the challenges faced by Zn-MnO2 batteries, we propose a hybrid Zn-MnO2 battery (HZMB) by coupling the neutral Zn anode with the acidic MnO2 cathode, wherein the neutral anode and acidic cathode are separated by a proton-shuttle-shielding and hydrophobic-ion-conducting membrane. Benefiting from the optimized reaction conditions for both the MnO2 cathode and Zn anode as well as the well-designed membrane, the HZMB exhibits a high working voltage of 2.05 V and a long lifespan of 2275 h (2000 cycles), breaking through the limitations of Zn-MnO2 batteries in terms of voltage and cycle life.

Stimulus context affects the phonemic categorization of temporally based word contrasts in adult cochlear-implant users.

Cochlear-implant (CI) users rely heavily on temporal envelope cues for speech understanding. This study examined whether their sensitivity to temporal cues in word segments is affected when the words are preceded by non-informative carrier sentences. Thirteen adult CI users performed phonemic categorization tasks that present primarily temporally based word contrasts: Buy-Pie contrast with word-initial stop of varying voice-onset time (VOT), and Dish-Ditch contrast with varying silent intervals preceding the word-final fricative. These words were presented in isolation or were preceded by carrier stimuli including a sentence, a sentence-envelope-modulated noise, or an unmodulated speech-shaped noise. While participants were able to categorize both word contrasts, stimulus context effects were observed primarily for the Buy-Pie contrast, such that participants reported more "Buy" responses for words with longer VOTs in conditions with carrier stimuli than in isolation. The two non-speech carrier stimuli yielded similar or even greater context effects than sentences. The context effects disappeared when target words were delayed from the carrier stimuli for ≥75 ms. These results suggest that stimulus contexts affect auditory temporal processing in CI users but the context effects appear to be cue-specific. The context effects may be governed by general auditory processes, not those specific to speech processing.

Decoupled aqueous batteries using pH-decoupling electrolytes.

Aqueous batteries have been considered as the most promising alternatives to the dominant lithium-based battery technologies because of their low cost, abundant resources and high safety. The output voltage of aqueous batteries is limited by the narrow stable voltage window of 1.23 V for water, which theoretically impedes further improvement of their energy density. However, the pH-decoupling electrolyte with an acidic catholyte and an alkaline anolyte has been verified to broaden the operating voltage window of the aqueous electrolyte to over 3 V, which goes beyond the voltage limitations of the aqueous batteries, making high-energy aqueous batteries possible. In this Review, we summarize the latest decoupled aqueous batteries based on pH-decoupling electrolytes from the perspective of ion-selective membranes, competitive redox couples and potential battery prototypes. The inherent defects and problems of these decoupled aqueous batteries are systematically analysed, and the critical scientific issues of this battery technology for future applications are discussed.

Controlled Vertically Aligned Structures in Polymer Composites: Natural Inspiration, Structural Processing, and Functional Application.

Vertically aligned structures, which are a series of characteristic conformations with thickness-direction alignment, interconnection, or assembly of filler in polymeric composite materials that can provide remarkable structural performance and advanced anisotropic functions, have attracted considerable attention in recent years. The past two decades have witnessed extensive development with regard to universal fabrication methods, subtle control of morphological features, improvement of functional properties, and superior applications of vertically aligned structures in various fields. However, a systematic review remains to be attempted. The various configurations of vertical structures inspired from biological samples in nature, such as vertically aligned structures with honeycomb, reed, annual ring, radial, and lamellar configurations are summarized here. Additionally, relevant processing methods, which include the transformation of oriented direction, external-field inducement, template method, and 3D printing method, are discussed in detail. The diverse applications in mechanical, thermal, electric, dielectric, electromagnetic, water treatment, and energy fields are also highlighted by providing representative examples. Finally, future opportunities and prospects are listed to identify current issues and potential research directions. It is expected that perspectives on the vertically aligned structures presented here will contribute to the research on advanced multifunctional composites.

Aging Effects on Cortical Responses to Tones and Speech in Adult Cochlear-Implant Users.

Age-related declines in auditory temporal processing contribute to speech understanding difficulties of older adults. These temporal processing deficits have been established primarily among acoustic-hearing listeners, but the peripheral and central contributions are difficult to separate. This study recorded cortical auditory evoked potentials from younger to middle-aged (< 65 years) and older (≥ 65 years) cochlear-implant (CI) listeners to assess age-related changes in temporal processing, where cochlear processing is bypassed in this population. Aging effects were compared to age-matched normal-hearing (NH) listeners. Advancing age was associated with prolonged P2 latencies in both CI and NH listeners in response to a 1000-Hz tone or a syllable /da/, and with prolonged N1 latencies in CI listeners in response to the syllable. Advancing age was associated with larger N1 amplitudes in NH listeners. These age-related changes in latency and amplitude were independent of stimulus presentation rate. Further, CI listeners exhibited prolonged N1 and P2 latencies and smaller P2 amplitudes than NH listeners. Thus, aging appears to degrade some aspects of auditory temporal processing when peripheral-cochlear contributions are largely removed, suggesting that changes beyond the cochlea may contribute to age-related temporal processing deficits.

Effect of Chronological Age on Pulse Rate Discrimination in Adult Cochlear-Implant Users.

Cochlear-implant (CI) users rely heavily on temporal envelope cues to understand speech. Temporal processing abilities may decline with advancing age in adult CI users. This study investigated the effect of age on the ability to discriminate changes in pulse rate. Twenty CI users aged 23 to 80 years participated in a rate discrimination task. They attempted to discriminate a 35% rate increase from baseline rates of 100, 200, 300, 400, or 500 pulses per second. The stimuli were electrical pulse trains delivered to a single electrode via direct stimulation to an apical (Electrode 20), a middle (Electrode 12), or a basal location (Electrode 4). Electrically evoked compound action potential amplitude growth functions were recorded at each of those electrodes as an estimate of peripheral neural survival. Results showed that temporal pulse rate discrimination performance declined with advancing age at higher stimulation rates (e.g., 500 pulses per second) when compared with lower rates. The age-related changes in temporal pulse rate discrimination at higher stimulation rates persisted after statistical analysis to account for the estimated peripheral contributions from electrically evoked compound action potential amplitude growth functions. These results indicate the potential contributions of central factors to the limitations in temporal pulse rate discrimination ability associated with aging in CI users.

Age-Related Temporal Processing Deficits in Word Segments in Adult Cochlear-Implant Users.

Aging may limit speech understanding outcomes in cochlear-implant (CI) users. Here, we examined age-related declines in auditory temporal processing as a potential mechanism that underlies speech understanding deficits associated with aging in CI users. Auditory temporal processing was assessed with a categorization task for the words dish and ditch (i.e., identify each token as the word dish or ditch) on a continuum of speech tokens with varying silence duration (0 to 60 ms) prior to the final fricative. In Experiments 1 and 2, younger CI (YCI), middle-aged CI (MCI), and older CI (OCI) users participated in the categorization task across a range of presentation levels (25 to 85 dB). Relative to YCI, OCI required longer silence durations to identify ditch and exhibited reduced ability to distinguish the words dish and ditch (shallower slopes in the categorization function). Critically, we observed age-related performance differences only at higher presentation levels. This contrasted with findings from normal-hearing listeners in Experiment 3 that demonstrated age-related performance differences independent of presentation level. In summary, aging in CI users appears to degrade the ability to utilize brief temporal cues in word identification, particularly at high levels. Age-specific CI programming may potentially improve clinical outcomes for speech understanding performance by older CI listeners.

Impact of depression on speech perception in noise.

Effective speech communication is critical to everyday quality of life and social well-being. In addition to the well-studied deficits in cognitive and motor function, depression also impacts communication. Here, we examined speech perception in individuals who were clinically diagnosed with major depressive disorder (MDD) relative to neurotypical controls. Forty-two normal-hearing (NH) individuals with MDD and 41 NH neurotypical controls performed sentence recognition tasks across three conditions with maskers varying in the extent of linguistic content (high, low, and none): 1-talker masker (1T), reversed 1-talker masker (1T_tr), and speech-shaped noise (SSN). Individuals with MDD, relative to neurotypical controls, demonstrated lower recognition accuracy in the 1T condition but not in the 1T_tr or SSN condition. To examine the nature of the listening condition-specific speech perception deficit, we analyzed speech recognition errors. Errors as a result of interference from masker sentences were higher for individuals with MDD (vs. neurotypical controls) in the 1T condition. This depression-related listening condition-specific pattern in recognition errors was not observed for other error types. We posit that this depression-related listening condition-specific deficit in speech perception may be related to heightened distractibility due to linguistic interference from background talkers.

Biometric identification of listener identity from frequency following responses to speech.

OBJECTIVE: We investigate the biometric specificity of the frequency following response (FFR), an EEG marker of early auditory processing that reflects phase-locked activity from neural ensembles in the auditory cortex and subcortex (Chandrasekaran and Kraus 2010, Bidelman, 2015a, 2018, Coffey et al 2017b). Our objective is two-fold: demonstrate that the FFR contains information beyond stimulus properties and broad group-level markers, and to assess the practical viability of the FFR as a biometric across different sounds, auditory experiences, and recording days. APPROACH: We trained the hidden Markov model (HMM) to decode listener identity from FFR spectro-temporal patterns across multiple frequency bands. Our dataset included FFRs from twenty native speakers of English or Mandarin Chinese (10 per group) listening to Mandarin Chinese tones across three EEG sessions separated by days. We decoded subject identity within the same auditory context (same tone and session) and across different stimuli and recording sessions. MAIN RESULTS: The HMM decoded listeners for averaging sizes as small as one single FFR. However, model performance improved for larger averaging sizes (e.g. 25 FFRs), similarity in auditory context (same tone and day), and lack of familiarity with the sounds (i.e. native English relative to native Chinese listeners). Our results also revealed important biometric contributions from frequency bands in the cortical and subcortical EEG. SIGNIFICANCE: Our study provides the first deep and systematic biometric characterization of the FFR and provides the basis for biometric identification systems incorporating this neural signal.

Machine Learning Approaches to Analyze Speech-Evoked Neurophysiological Responses.

Purpose Speech-evoked neurophysiological responses are often collected to answer clinically and theoretically driven questions concerning speech and language processing. Here, we highlight the practical application of machine learning (ML)-based approaches to analyzing speech-evoked neurophysiological responses. Method Two categories of ML-based approaches are introduced: decoding models, which generate a speech stimulus output using the features from the neurophysiological responses, and encoding models, which use speech stimulus features to predict neurophysiological responses. In this review, we focus on (a) a decoding model classification approach, wherein speech-evoked neurophysiological responses are classified as belonging to 1 of a finite set of possible speech events (e.g., phonological categories), and (b) an encoding model temporal response function approach, which quantifies the transformation of a speech stimulus feature to continuous neural activity. Results We illustrate the utility of the classification approach to analyze early electroencephalographic (EEG) responses to Mandarin lexical tone categories from a traditional experimental design, and to classify EEG responses to English phonemes evoked by natural continuous speech (i.e., an audiobook) into phonological categories (plosive, fricative, nasal, and vowel). We also demonstrate the utility of temporal response function to predict EEG responses to natural continuous speech from acoustic features. Neural metrics from the 3 examples all exhibit statistically significant effects at the individual level. Conclusion We propose that ML-based approaches can complement traditional analysis approaches to analyze neurophysiological responses to speech signals and provide a deeper understanding of natural speech and language processing using ecologically valid paradigms in both typical and clinical populations.

Taking Attention Away from the Auditory Modality: Context-dependent Effects on Early Sensory Encoding of Speech.

Increasing visual perceptual load can reduce pre-attentive auditory cortical activity to sounds, a reflection of the limited and shared attentional resources for sensory processing across modalities. Here, we demonstrate that modulating visual perceptual load can impact the early sensory encoding of speech sounds, and that the impact of visual load is highly dependent on the predictability of the incoming speech stream. Participants (n = 20, 9 females) performed a visual search task of high (target similar to distractors) and low (target dissimilar to distractors) perceptual load, while early auditory electrophysiological responses were recorded to native speech sounds. Speech sounds were presented either in a 'repetitive context', or a less predictable 'variable context'. Independent of auditory stimulus context, pre-attentive auditory cortical activity was reduced during high visual load, relative to low visual load. We applied a data-driven machine learning approach to decode speech sounds from the early auditory electrophysiological responses. Decoding performance was found to be poorer under conditions of high (relative to low) visual load, when the incoming acoustic stream was predictable. When the auditory stimulus context was less predictable, decoding performance was substantially greater for the high (relative to low) visual load conditions. Our results provide support for shared attentional resources between visual and auditory modalities that substantially influence the early sensory encoding of speech signals in a context-dependent manner.

Tracing the Trajectory of Sensory Plasticity across Different Stages of Speech Learning in Adulthood.

Although challenging, adults can learn non-native phonetic contrasts with extensive training [1, 2], indicative of perceptual learning beyond an early sensitivity period [3, 4]. Training can alter low-level sensory encoding of newly acquired speech sound patterns [5]; however, the time-course, behavioral relevance, and long-term retention of such sensory plasticity is unclear. Some theories argue that sensory plasticity underlying signal enhancement is immediate and critical to perceptual learning [6, 7]. Others, like the reverse hierarchy theory (RHT), posit a slower time-course for sensory plasticity [8]. RHT proposes that higher-level categorical representations guide immediate, novice learning, while lower-level sensory changes do not emerge until expert stages of learning [9]. We trained 20 English-speaking adults to categorize a non-native phonetic contrast (Mandarin lexical tones) using a criterion-dependent sound-to-category training paradigm. Sensory and perceptual indices were assayed across operationally defined learning phases (novice, experienced, over-trained, and 8-week retention) by measuring the frequency-following response, a neurophonic potential that reflects fidelity of sensory encoding, and the perceptual identification of a tone continuum. Our results demonstrate that while robust changes in sensory encoding and perceptual identification of Mandarin tones emerged with training and were retained, such changes followed different timescales. Sensory changes were evidenced and related to behavioral performance only when participants were over-trained. In contrast, changes in perceptual identification reflecting improvement in categorical percept emerged relatively earlier. Individual differences in perceptual identification, and not sensory encoding, related to faster learning. Our findings support the RHT-sensory plasticity accompanies, rather than drives, expert levels of non-native speech learning.

Hidden Markov modeling of frequency-following responses to Mandarin lexical tones.

BACKGROUND: The frequency-following response (FFR) is a scalp-recorded electrophysiological potential reflecting phase-locked activity from neural ensembles in the auditory system. The FFR is often used to assess the robustness of subcortical pitch processing. Due to low signal-to-noise ratio at the single-trial level, FFRs are typically averaged across thousands of stimulus repetitions. Prior work using this approach has shown that subcortical encoding of linguistically-relevant pitch patterns is modulated by long-term language experience. NEW METHOD: We examine the extent to which a machine learning approach using hidden Markov modeling (HMM) can be utilized to decode Mandarin tone-categories from scalp-record electrophysiolgical activity. We then assess the extent to which the HMM can capture biologically-relevant effects (language experience-driven plasticity). To this end, we recorded FFRs to four Mandarin tones from 14 adult native speakers of Chinese and 14 of native English. We trained a HMM to decode tone categories from the FFRs with varying size of averages. RESULTS AND COMPARISONS WITH EXISTING METHODS: Tone categories were decoded with above-chance accuracies using HMM. The HMM derived metric (decoding accuracy) revealed a robust effect of language experience, such that FFRs from native Chinese speakers yielded greater accuracies than native English speakers. Critically, the language experience-driven plasticity was captured with average sizes significantly smaller than those used in the extant literature. CONCLUSIONS: Our results demonstrate the feasibility of HMM in assessing the robustness of neural pitch. Machine-learning approaches can complement extant analytical methods that capture auditory function and could reduce the number of trials needed to capture biological phenomena.