bluuebunny/crossref_metadata_2025 huggingface dataset:
A five-year longitudinal investigation of duration and temporal variability in children’s speech production
Authors: Smith Bruce L. , Kenney Mary Kay
Published: July 2002

Although cross-sectional (group) investigations of children’s speech production have provided important findings about average performance and general patterns of development, one limitation of such studies is that they tend to obscure details concerning the development of individual children. In the present study, two children were recorded at approximately 8-month intervals for about 5 years as they produced 20 repetitions (per session) of several different target stimuli. One of the children was about 11/2 years old at the onset of the study, and the other was about 4 years of age. Acoustic measurements of various temporal aspects of their speech were obtained from spectrographic displays. The findings for both children showed certain patterns that supported the general claim (based on cross-sectional data) that segment and word duration and their associated temporal variability tend to decrease with increased age. However, there were also a number of instances in which the children’s temporal variability and, in particular, their duration measures showed little or no change across the five years they were followed. Although the findings are from just two children, the implications of these longitudinal data are important for gaining a more detailed and comprehensive understanding of children’s speech production development.
Difference limens for frequency and amplitude perturbation as a function of fundamental frequency and waveshape
Authors: Campbell Shari L.
Published: July 2002

Three-interval forced-choice adaptive procedures were used to estimate difference limens (DLs) for signals with either frequency perturbation (jitter) or amplitude perturbation (shimmer). A time-domain synthesis technique was used to generate sinusoidal and triangular waves with specified amounts of both perturbation types (defined as the mean absolute value, in percent, of the first-order perturbation function) for each of two mean fundamental frequencies (100 and 200 Hz). Standard stimuli had neither frequency nor amplitude perturbation. Sequential characteristics of the signals were determined via autocorrelation analyses. Signals were 900 ms in duration and were presented monaurally at 80 dB SPL via insert earphones to ten listeners with normal hearing. Up to 12 estimates were obtained for each of the eight signal types. Group average DLs ranged from 0.07% (frequency perturbation, 200-Hz triangular wave) to 6.20% (amplitude perturbation, 100 Hz triangular wave). For a given fundamental frequency and waveshape, DLs were smaller for frequency perturbation than for amplitude perturbation. Within a perturbation type, DLs were smaller for triangular waves with frequency perturbation and for sine waves with amplitude perturbation. [Work supported by The University of Georgia Research Foundation.]
Neonates attend to perceptual cues to rudimentary grammatical categories
Authors: Shi Rushen , Werker Janet
Published: July 2002

To acquire the rules by which words are combined to form phrases and sentences, infants must first learn to assign words to grammatical catego- ries such as nouns, prepositions, etc. This study is based on the assumption that infants initially derive the binary, superordinate lexical and functional categories from perceptual cues in the input. These two categories are present in all human languages, and recent work reveals similar distinctive acoustic and phonological cues across languages [R. Shi, J. Morgan, and P. Allopenna, J. Child Language (in press)]. For this study it was therefore proposed that there exists an innate mechanism leading to initial sensitivity to cues separating the two universal categories. Newborns were tested using the high-amplitude sucking paradigm. Stimuli were multiple lexical and function word tokens randomly selected and sliced from natural infant-directed utterances of an English-speaking mother. After being habituated to a word set of one category, infants were tested on either words of the other category or new words from the same category. The results showed that infants’ recovery was significantly greater to words of the other category. This evidence supports a predisposed sensitivity which may serve as an initial foundation for the formation of early grammatical categories.
A beamforming paradox: Using far-field techniques to design a near-field microphone array
Authors: Ward Darren B. , Kennedy Rodney A. , Abhayapala Thushara
Published: July 2002

A new method of designing a beamformer having a desired near-field beampattern is presented. Although a plethora of techniques have been proposed for far-field beamformer design (where the received wavefronts are planar), these methods generally result in severe beampattern degradation when used in a near-field environment (when the source is sufficiently close to the array that the spherical nature of the wavefronts must be taken into account). In this paper a computationally simple design procedure is presented in which established far-field design techniques can be employed to achieve near-field beampatterns with high accuracy. The theoretical underpinnings of this procedure are based on the spherical solution to the wave equation. The method can be applied to the problem of designing a microphone array for speech acquisition from a near-field talker.
Dispersion of sound in a sandy silt sediment
Authors: Chotiros Nicholas P.
Published: July 2002

Sound pulses penetrating from water into a sandy silt were found to be dispersive in the 1- to 10-kHz band. Pulses were projected from a parametric source into a sandy silt sediment and received by a buried array of hydrophones. The signals were coherently processed for direction and speed of the sound pulse as a function of frequency. The sound speed was found to increase with frequency at a rate greater than that expected from simple attenuation. Acoustic propagation was modeled with Biot’s theory using constant coefficients, and model predictions were unable to match the observed dispersion. One possible explanation is a frequency-dependent frame bulk modulus, due to relaxation effects associated with the interaction between the pore fluid and the grain-grain contacts. [Work supported by ONR 321 OA.]
Evaluation of Biot–Stoll theory for conversion of geology to geoacoustic data in shallow water
Authors: Badiey Mohsen , Cheng Alexander H. D. , Mu Yongke
Published: July 2002

A procedure for estimating acoustic-wave velocity and attenuation in ocean sediment using a minimum amount of geological and geotechnical data is demonstrated. First, the Biot–Stoll theory is presented. Next, various asymptotic formulas for the attenuation coefficient are derived for high, low, and intermediate frequencies. These expressions clearly isolate the effects of the intergranular Coulomb friction and fluid viscous dissipation on the attenuation of shear and compressional waves. Under the constraint of a minimum amount of geological and geotechnical information, a sequence of empirical equations is compiled to convert basic data, such as the blow count number from a standard penetration test or shipboard density, into sediment geoacoustic properties. As a demonstration, two well-known field cases, the Atlantic Generating Station (AGS) site and the Atlantic Margin Coring (AMCOR 6010) site, are examined. By incorporating the uncertainty involved in the data collection, the estimated geoacoustical parameters are provided with a standard deviation.
A synthetic array measurement of a fast compressional and a slower wave in an unconsolidated water-saturated porous medium
Authors: Simpson Harry J. , Houston Brian H.
Published: July 2002

An investigation of sound waves propagating in an unconsolidated water-saturated porous medium has been conducted in the NRL shallow-water laboratory. To minimize the interaction of the water–sand interface, a transducer was buried approximately 1.5 m facing up toward the sand–water interface. The unconsolidated water-saturated porous medium is a 3.0-m deep bed of a manufactured 212-μm mean diameter sand. To obtain a short pulse that provides better temporal resolution of the acoustical waves propagating in the media, a 1-3 composite transducer was used. The sound field is measured with a single hydrophone that is initially buried just above the source and then incrementally pulled up through the sand toward the sand–water interface. This provide a synthetic array meaurement of the sound field directly above the transducer. A 1680-m/s fast compressional wave and a 550-m/s slower wave are easily observed using both temporal and spatial analysis techniques. Comparisons of these wave speeds with predictions from a Biot model are discussed. [Work supported by ONR.]
Acoustic census of sperm whales in the eastern temperate North Pacific
Authors: Barlow Jay , Taylor Barbara
Published: July 2002

An NOAA/ONR acoustic line-transect survey was conducted in spring 1997 to estimate the abundance of sperm whales in the eastern temperate North Pacific using a 52-m research vessel. An ITI hydrophone array was towed at 100-m depth as the vessel surveyed approximately 25 000 km of predetermined transect lines at 8 kn. Acoustic signals received by a pair of hydrophones were digitized and sent up to the ship via a coaxial tow cable. Bearing angles to the locations of sperm whales were calculated in real time based on differences in signal arrival times between the two hydrophones, and whale locations were determined by the convergence of bearing lines as the ship continued along its course. The ship was maneuvered to resolve the left/right ambiguity in whale locations and, during daylight hours, was directed to this estimated location to obtain visual estimates of group size when the whales surfaced. A total of 102 distinct groups of sperm whales were acoustically detected with sufficient amplitude to estimate bearing lines. ‘‘Slow clicks’’ (with a period of 4–8 s) were detected at ranges up to 20 nmi, whereas the more typical sperm whale clicks (with a period of 0.5–1.0 s) were typically heard at less than 5 nmi.
High-frequency surface forward scattering and its relation to the directional wave spectrum: Model and data comparisons employing the Kirchhoff approximation
Authors: Dahl Peter H.
Published: July 2002

Measurements of the spatial coherence of high-frequency (30-kHz) sound forward scattered from the sea surface are discussed, along with a simple interpretive model based on the Kirchhoff approximation. The data are from an experiment conducted off south Florida in waters 25-m deep. For the model, the bistatic cross section is first computed via the Kirchhoff integral, and a marginal density function for intensity versus horizontal arrival angle generated; this function is then Fourier transformed to give a model for the horizontal spatial coherence. The Kirchhoff integral requires a representation of the two-dimensional surface wave correlation function, which is itself derived from estimates of the directional wave spectrum. The latter were measured with a directional wave buoy that operated in the immediate vicinity of the acoustic measurements. A model [Donelan et al., Philos. Trans. R. Soc. London, Ser. A 315, 509–562 (1985)] is used to fill in for the necessary directional spreading information. Sensitivities of horizontal spatial coherence to array acquisition geometry, wind speed, surface wave directional properties and mean-square slope, are discussed. [Work supported by ONR Code 321OA.]
A simple approach for modeling acoustic scattering from rocks and sea shells lying on the ocean floor
Authors: Feuillade C. , Meredith R. W.
Published: July 2002

Acoustic reverberation in the ocean is due to collective scattering from a large number and diverse range of distributed objects. In this work, a model for predicting the sonar target strengths of an important class of clutter objects, i.e., rocks and sea shells lying on the ocean floor, is presented. The model incorporates a simplified approach, in which rocks are represented by either rigid movable spheres or elastic spheres, a technique which has been previously used to model aqueous suspensions of sand over the frequency range of interest. Sea shells are represented by water-filled spherical shells. The model predicts scattering strength values for areas of the ocean floor covered by randomized arrangements of rocks and shells, using sizes, numbers, geologic type, and material compositions typically found on the bottom. The scattering as a function of azimuth is determined by coherent addition, and allows both monostatic and bistatic geometries to be investigated. [Work supported by ONR/NRL]
Multiple scattering owing to sediment volume inhomogeneities
Authors: Tang Dajun
Published: July 2002

Multiple scattering owing to strong sediment volume inhomogeneities is discussed using the formally averaged approach, which was originated from the quantum field theory and has been extensively applied to wave propagation in random media. Random spatial variations of sediment density as well as sound speed are considered. While it is well known that the sound-speed variations result in a renormalized complex wave number, when the coherent field is concerned it is found that the density variations can also be renormalized, but they manifest themselves as a formal density gradient in the wave equation. This can be identified as a new loss mechanism of the coherent field. When both sound speed and density variations are included, the cross correlation between sound speed and density is an important quantity to measure since it will influence the scattering intensity to a non-negligible extent. Numerical examples will be presented and discussed. [Work supported by ONR Code 321OA.]
Acoustic propagation across a roughened fluid–fluid interface
Authors: Lopes Joseph L. , Paustian Iris C. , Lim Raymond
Published: July 2002

A laboratory experiment was conducted to investigate the effects of small-scale random roughness on acoustic propagation across a fluid–fluid interface. This experiment utilized an acoustic source mounted onto a movable platform, several hydrophones, and two immiscible fluids (vegetable oil and glycerin). The effects of roughness on propagation across the interface were determined by floating small polystyrene beads at the interface between these fluids. Data were collected as functions of frequency, grazing angle, and varying degrees of roughness (bead size and with/without beads). The goal of this experiment was twofold: (1) to test roughness diffraction as a mechanism for enhanced acoustic transmission at grazing angles shallower than critical, and (2) to assess the temporal and spatial coherence of the transmitted signal. Analyzed data of this work will be presented and compared to results of propagation into underwater sediments reported in the literature. [Work supported by ONR.]
Discriminability of correlated bursts of reproducible noise
Authors: Fallon Susan M.
Published: July 2002

Discriminability of pairs of 100-ms bursts of noise was measured using a same–different psychophysical method. In the first condition, the correlation between bursts in a pair was fixed at 1.0 during each same trial. On each different trial, bursts were identical except for τ ms of independent noise located at either the beginning, the middle, or the end of the pairs. The correlation between bursts presented on each different trial was increased from 0.0 by decreasing the duration of τ. The second condition was the converse of the first; the correlation between bursts presented on each different trial was fixed at 0.0 and the correlation between bursts presented on each same trial was decreased from 1.0. As the τ ms of either independent (condition 1) or the perfectly correlated (condition 2) noise is moved from the beginning to the end of bursts, discriminability increases in the first condition and decreases in the second condition. These results suggest that a ‘‘difference’’ is a more salient cue in the discrimination task than a ‘‘sameness’’ and are discussed in terms of a correlational model. [Work supported by NIH and AFOSR.]
Experiments on the relation of shock wave parameters to stone disintegration
Authors: Dreyer Thomas , Riedlinger Rainer E. , Steiger Eckard
Published: July 2002

The sound field of different focusing piezoelectric transducers designed for lithotripsy was investigated. The shock wave parameters according to proposed standards, e.g., FDA Draft 1991, were determined. The parameters achieved are based on measurements using a fiber-optical probe hydrophone. In contrast to PVDF-based hydrophones, this hydrophone is able to give a correct representation also of the tensile components of a complete signal and provides a higher spatial resolution. Thus some shock wave parameters like beam energy can be calculated more precisely. The different lithotripter pulses were applied to model stones in vitro, recording the amounts of removed material. Fragmentation results were compared with the different parameters. Attempts were made to arrange these parameters according to their relevance to disintegration. The evaluation of these experiments revealed up to now that there is no significant relation between some of the shock wave parameters and fragmentation efficiency. It is concluded that most of the proposed parameters do not describe well the efficacy of different lithotripter sources on concrements.
Enhancement of the Q of a nonlinear acoustic resonator by active suppression of harmonics
Authors: Gusev Vitalyi E. , Bailliet Hélène , Lotton Pierrick , Job Stéphane , Bruneau Michel
Published: July 2002

Finite-amplitude stationary acoustic waves in a closed resonator subjected to simultaneous excitation at fundamental frequency and its second harmonic are analyzed in the frame of the second-order nonlinear theory. The conditions when the dual-frequency excitation leads to a quality factor Q higher than in the case of a single-frequency excitation are derived. The Q enhancement can be explained in terms of active suppression of cascade processes of the generation of higher harmonics. The second harmonic generated in the resonator is compensated by the second harmonic radiated by the piston. Suppression of higher harmonics also can be explained as being due to effective down conversion of energy from the second harmonic to the fundamental wave in the nonlinear parametric process.
The APEX model: From articulatory positions to sound
Authors: Stark Johan , Ericsdotter Christine , Lindblom Björn , Sundberg Johan
Published: July 2002

From input specifications for lips, tongue tip, tongue body, jaw opening and larynx height, APEX constructs an articulatory profile which is used to derive an estimate of the associated area function and the formant frequencies. The geometry of the APEX vocal tract is customized according to x-ray data from an individual speaker [P. Branderud et al., Fonetik 98, 168–171 (1998) and www.ling.su.se/fon/publications/]. The input measurements are contours sampled as x/y points for the shape of fixed structures such as the mandible, hard palate, and posterior pharyngeal wall, and certain selectively chosen configurations of articulators whose shape and position vary (e.g., lips, tongue tip, tongue body). Observed tongue contours of /i/, /u/ and /a/, and ‘‘rest’’ are used to provide reference contours for the rules of APEX. The general philosophy behind the procedure is to have APEX represent certain key configurations as faithfully as possible and then derive intermediate articulations by a set of physiologically motivated interpolation rules [B. Lindblom and J Sundberg, J. Acoust. Soc. Am. 50, 1166–1179 (1979)]. An evaluation of the articulatory and acoustic performance of APEX will be presented. [Work supported by the HSFR and RJ research councils of Sweden.]
Ultrasonic beam models: An edge element approach
Authors: Lerch Terence P. , Schmerr Lester W. , Sedov Alexander
Published: July 2002

A new method, the edge element method, has been developed to numerically evaluate a variety of ultrasonic transducer beam models. The edge element technique divides the transducer surface into a web of sources consisting of radiating straight line elements whose individual contributions can be evaluated analytically. When all of these edge elements are summed, the wave field of the transducer can be obtained at any field point in the surrounding medium for a given ultrasonic frequency. To demonstrate the versatility of this approach, it is shown that edge elements can accurately model the wave fields radiated into a fluid by focused and unfocused transducers of circular and noncircular apertures.
Flow generated around particle clusters in a rotating ultrasonic waveguide
Authors: Whitworth Glenn
Published: July 2002

A chamber cavity, which has a square cross section and pressure-release walls, is used to produce a well-defined, 160-kHz standing ultrasonic field. A suspension of latex microspheres in aqueous metrizamide fills the chamber. The chamber rotates about a horizontal axis producing the centripetal force necessary to contain the buoyant spheres in the axial region. At low particle concentrations, clusters of microspheres form at half-wavelength intervals near the axial positions of acoustic pressure amplitude (p0) minima, as expected because of rotational and acoustic radiation forces. At higher concentrations, additional particle distributions are often seen that suggest the presence of flow. When high concentrations of larger particles are used, small clusters also form at axial positions of p0 maxima. Theory for acoustic streaming in a rotating fluid predicts flow speeds that are too small to account for the observed flow. Reasonable agreement with observations is obtained using a theory for flow generated by the buoyant gravitational force acting on the clusters.
Masker laterality and cueing in forward-masked intensity discrimination
Authors: Schlauch Robert S. , Clement Bart R. , Ries Dennis T. , DiGiovanni Jeffrey J.
Published: July 2002

Forward-masked intensity discrimination was measured as a function of level in experiments designed to reveal insights into the mechanism(s) underlying the midlevel elevation of the Weber fraction. The standard and maskers were 1.0-kHz tones that were separated by 100 ms. Performance was measured for listeners with normal hearing using an adaptive procedure. In experiment 1, intensity discrimination was measured in the presence of an ipsilateral masker (80 dB SPL), a contralateral masker (93 dB SPL), and a binaural (dichotic) masker produced by combining the ipsilateral and contralateral maskers. Listeners perceived only the contralateral masker in the binaural-masker condition. The contralateral masker produced a small midlevel elevation of the Weber fraction. The ipsilateral masker and the binaural masker produced a large, midlevel elevation of the Weber fraction. Experiment 2 found that a two-tone masker resulted in a reduction (improvement) in the Weber fraction for some conditions, but the midlevel elevation remained for all subjects in this cue-tone condition. Experiment 3 demonstrated that cross talk could not account for all of the masking observed with contralateral maskers. Taken together, the results suggest that a single complex mechanism or multiple mechanisms may be responsible for the masking seen in these experiments. On the basis of the cueing results, it is concluded that a portion of the masking is due to cognitive factors; however, a sensory mechanism cannot be ruled out for the remaining portion, based on the results of these experiments. Finally, a small but significant amount of masking due to contralateral maskers places the mechanism for this outcome central to the cochlear nucleus.
The Huygens entrainment phenomenon and thermoacoustic engines
Authors: Spoor P. S. , Swift G. W.
Published: July 2002

The earliest known reference to the mode-locking, or entrainment, of two maintained oscillators is Christiaan Huygens’ description of two pendulum clocks “falling into synchrony” when hung on the same wall. We describe an analogous phenomenon in acoustics—the mode-locking of two thermoacoustic engines which have their cases rigidly welded together, but which are otherwise uncoupled. This “mass-coupling” might compete with acoustic coupling when the latter is used to enforce antiphase mode-locking in such engines, for vibration cancellation. A simple theory relating the phase difference between the engines in the locked state to the corresponding ratio of their pressure amplitudes is in excellent agreement with theory and numerical simulations. The theory’s prediction relating the phase difference to the engines’ natural frequency difference is qualitatively confirmed by experiment, despite larger experimental uncertainties. The mass coupling is relatively weak compared to the aforementioned acoustic coupling, and in general occurs in antiphase, so we conclude that mass coupling will not interfere with vibration cancellation by acoustic coupling in most circumstances.
On the Flow and Activation Energy of Branched Polyethylene Melts
Authors: Porter Roger S. , Knox Jack P. , Johnson Julian F.
Published: July 2002

Examination of the flow of branched polyethylene melts leads to molecular weight-viscosity, activation energy-molecular weight, and activation energy-shear stress relationships which are anomalous when compared to the behavior of most polymers. In addition, the activation energy for viscous flow is much higher than would be expected by a comparison with linear polyethylene. Published data on branched polyethylene are examined, and various explanations for the anomalous behavior are considered. Order in the melt and abnormal melt volumes are rejected as possible explanations for the anomalous effects. It is shown that short branches contribute at most ca. 2 kcal to the activation energy at zero shear and cannot, therefore, be completely responsible for the observed values. Long chain branches are postulated for several reasons to be responsible for the anomalous flow behavior and activation energy. The mechanism by which long chain branches cause the anomalous behavior of branched polyethylene is not established, but several possible explanation are discussed.
The Rheology of Hydroxyethyl Cellulose Solutions
Authors: Naik S. C. , Pittman J. F. T. , Richardson J. F.
Published: July 2002

A systematic and detailed study of the viscous behavior of aqueous hydroxyethyl cellulose solutions has been made in a cone-and-plate viscometer over very wide ranges of shear rate and temperature. High shear stability and high degrees of pseudoplasticity have been observed. The rheograms have followed the Ostwald-de Waele model. Simple and accurate expressions have been formulated relating temperature, solution-concentration and power law exponent to consistency coefficient; also the solution-concentration to activation energy.
Rheo-optical studies of stress-induced phase changes in blends exhibiting UCST: Polystyrene and polyisobutylene
Authors: Wu R. , Shaw M. T. , Weiss R. A.
Published: July 2002

Phase transition for blends of polystyrene (PS) (Mw=800, Mw/Mn=1.3)/polyisobutylene (PIB) (Mw=500) were studied in the quiescent state and under shear flow. The cloud points of blends were determined by turbidity measurements at a fixed cooling rate of 0.5 °C/min. The phase diagram of PS/PIB blends shows a UCST behavior with a bimodal miscibility gap at low temperature. The shear effects on the phase transition behavior of PS/PIB blend was investigated by a flow-turbidity apparatus which was constructed by modifying a Rheometrics Mechanical Spectrometer (RMS). No shear-induced phase separation was observed in the one-phase region. For temperatures within the two-phase region, the transmitted light intensity increased abruptly when the shear was applied. The intensities decreased and approached to the initial values when the shear was removed. Several possible explanations will be discussed to explain these results. The one that appears to be most valid is that of shear-induced phase mixing.
A Population‐Based Study Evaluating Retention in Rheumatology Care Among Patients With Rheumatoid Arthritis
Authors: Barber Claire E. H. , Lacaille Diane , Croxford Ruth , Barnabe Cheryl , Marshall Deborah A. , Abrahamowicz Michal , Xie Hui , Avina‐Zubieta J. Antonio , Esdaile John M. , Hazlewood Glen , Faris Peter , Katz Steven , MacMullan Paul , Mosher Dianne , Widdifield Jessica
Published: May 2022

Objective

The study objective was to assess adherence to system‐level performance measures measuring retention in rheumatology care and disease modifying anti‐rheumatic drug (DMARD) treatment in rheumatoid arthritis (RA).

Methods

We used a validated health administrative data case definition to identify individuals with RA in Ontario, Canada, between 2002 and 2014 who had at least 5 years of potential follow‐up prior to 2019. During the first 5 years following diagnosis, we assessed whether patients were seen by a rheumatologist yearly and the proportion dispensed a DMARD yearly (in those aged ≥66 for whom medication data were available). Multivariable logistic regression analyses were used to estimate the odds of remaining under rheumatologist care.

Results

The cohort included 50,883 patients with RA (26.1% aged 66 years and older). Over half (57.7%) saw a rheumatologist yearly in all 5 years of follow‐up. Sharp declines in the percentage of patients with an annual visit were observed in each subsequent year after diagnosis, although a linear trend to improved retention in rheumatology care was seen over the study period (P < 0.0001). For individuals aged 66 years or older (n = 13,293), 82.1% under rheumatologist care during all 5 years after diagnosis were dispensed a DMARD annually compared with 31.0% of those not retained under rheumatology care. Older age, male sex, lower socioeconomic status, higher comorbidity score, and having an older rheumatologist decreased the odds of remaining under rheumatology care.

Conclusion

System‐level improvement initiatives should focus on maintaining ongoing access to rheumatology specialty care. Further investigation into causes of loss to rheumatology follow‐up is needed.
Phase Separation: “The Master Key” to Deciphering the Physiological and Pathological Functions of Cells
Authors: Wei Chuzhong , Li Mingdong , Li Xinming , Lyu Jianxin , Zhu Xiao
Published: May 2022

Phase separation is a hot research field at present. It involves almost all aspects of cells and plays a significant role in cells, promising to be “a master key” in unlocking the mysteries of nature. In this review, the factors that affect phase separation are introduced, such as own component, electrostatic interaction, and chemical modification. Furthermore, the physiological roles of phase separation in cells, including molecules transport channel, gene expression and regulation, cellular division and differentiation, stress response, proteins refolding and degradation, cell connections, construction of skin barrier, and cell signals transmission, are highlighted. However, the disorder of phase separation leads to pathological condensates, which are associated with neurodegenerative diseases, tumors, and severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). This relationship is considered the potential target for developing corresponded drugs and therapy. Some drugs targeting phase separation have improved meaningful, such as tankyrase, lipoamide, oligonucleotides, elvitagravir, nilotinib, CVL218, PJ34. All in all, mystery phase separation provides a new viewpoint for researchers to explore cells, and is expected to solve many unknown phenomena in nature.
Cell Membrane‐Inspired Graphene Nanomesh Membrane for Fast Separation of Oil‐in‐Water Emulsions
Authors: Liu Yanan , Coppens Marc‐Olivier
Published: May 2022

Graphene exhibits fascinating prospects for preparing high‐performance membranes with fast water transport, due to its low friction with water and extreme thinness. However, for graphene‐assembled membranes, each molecule passing through the membrane should bypass many graphene sheets, which lengthens the molecular pathways and increases the mass transfer resistance. Herein, a graphene nanomesh (GNM) membrane is fabricated that is inspired by cell membranes, including aquaporins with their hydrophilic gate for selective transport and hydrophobic channel for low friction with water, thus resulting in fast water transport, as well as hydrophilic polymer brushes on the membrane surface for fouling resistance. GNM is synthesized by etching nanopores on graphene oxide (GO) nanosheets to significantly shorten the water transport channels, whereas the hydrophobic graphene sheets lead to low water friction; in combination, ultra‐fast, selective water flux is achieved. Also, hydrophilic polymer chitosan is utilized to modify GNM to construct a hydration layer, which suppresses foulants from touching the membrane surface. Accordingly, the permeance of the cell membrane‐inspired graphene nanomesh membrane reaches almost 4000 L m–2 h–1 bar–1, which is about 260 times the permeance in a GO membrane, and the membranes show superior antifouling properties for separating various surfactant‐stabilized oil‐in‐water emulsions.
Fast Large‐Stroke Sheath‐Driven Electrothermal Artificial Muscles with High Power Densities
Authors: Hu Xinghao , Jia Jingjing , Wang Yingming , Tang Xintian , Fang Shaoli , Wang Yilun , Baughman Ray H. , Ding Jianning
Published: May 2022

Electrothermal carbon nanotube (CNT) yarn muscles can provide large strokes during thermal cycling. However, the slow cooling rate of thermal muscles limits their applications, since large diameter prior‐art thermal muscles cannot be rapidly cycled. Herein, a fast thermally powered sheath‐driven yarn muscle that uses a hybrid CNT sheath and an inexpensive polymer core, is reported. The stroke recovery rate for the hybrid muscle is much lower at all frequencies than for about the same diameter sheath‐driven muscle, which means that the full cycle contractile mechanical power is much higher than for comparable prior‐art hybrid muscle. More specifically, the coiled sheath‐driven muscle contracts 14.3% at 1 Hz and 7.3% at 8 Hz in air when powered by a square‐wave electrical voltage input, which is 2.9‐ and 11.4‐times the stroke of the coiled hybrid muscle at these respective frequencies. An average power density of 12 kW kg−1 is obtained for a sheath‐driven muscle, which is 42‐times that for human skeletal muscle. These high‐performance results since the heating that drives fast actuation cycles are largely restricted to the muscle sheath, and this sheath is in direct contact with ambient temperature air.
Unraveling the Correlations between Mechanical Properties, Miscibility, and Film Microstructure in All‐Polymer Photovoltaic Cells
Authors: Zhou Kangkang , Xian Kaihu , Qi Qingchun , Gao Mengyuan , Peng Zhongxiang , Liu Junwei , Liu Yang , Li Saimeng , Zhang Youdi , Geng Yanhou , Ye Long
Published: May 2022

The rapid development of low bandgap polymer acceptors has promoted the efficiency up to ≈17% for all‐polymer solar cells (all‐PSCs). Nevertheless, the polymeric blend film, core to the photoelectric conversion of all‐PSCs, has not been thoroughly understood in terms of the influence and regulatory factors of mechanical properties, which hinders the advances in flexible and wearable applications. Herein, a range of characterization methods is combined to investigate the mechanical properties, miscibility, and film microstructure of the blends based on several representative polymer donors (PTzBI‐Si, PTVT‐T, PM6 and PTQ10) and a benchmark polymer acceptor N2200, and to further reveal the miscibility‐property relationships of the miscibility property. The results stress that fracture behaviors and elastic moduli of these blends with varied compositions show different changing trends, which are affected by molecular interactions and aggregated structure of the blends. The elastic moduli of the four all‐polymer blends can be nicely predicted by different models that are deduced from macromolecular mechanics. Most crucially, the correlations between elastic modulus, morphology, and miscibility of all‐polymer blends are elucidated for the first time. The derived relationships is validated with another high‐efficiency blend and will be the key to the successful fabrication of mechanically robust and stretchable all‐PSCs with high efficiency.
2D Amorphous Mo‐Doped CoB for Bidirectional Sulfur Catalysis in Lithium Sulfur Batteries
Authors: Feng Tao , Zhao Teng , Zhang Nanxiang , Duan Yuzhen , Li Li , Wu Feng , Chen Renjie
Published: May 2022

The amorphous metal boride materials are attractive catalyst for advanced lithium sulfur batteries, but their catalytic mechanism remains unclear. Herein, 2D amorphous Mo‐doped cobalt boride (Co7Mo3B) is designed for the first time as bidirectional sulfur catalysis by rapid chemical reduction. The atom cluster structure of Co7Mo3B is revealed by theoretical calculation. Electron paramagnetic resonance test further confirms that Co7Mo3B has interstitial compound structure characteristics. Experimental results show that the porous 2D nanosheets structure and the interaction of Mo, B, Co atoms contribute to enhanced conductivity, high long‐chain lithium polysulfides affinity, and reversible Li2S nucleation and dissociation, thus accelerating LiPSs reduction and Li2S oxidation kinetics. In addition, the interstitial Co7Mo3B enables intercalation of Li and B during charging–discharging while keeping the structure stable. As a result, the S cathode with Co7Mo3B catalyst delivers good life (1000 cycles at 5 C), superior rate performance (10 C). Even at high sulfur areal loading of 6.79 mg cm–2 and electrolyte/sulfur ratio of 5 μL mg–1, the Co7Mo3B/S composite cathode still exhibits good areal capacity and capacity retention rate.
ROS Turn Nanoparticle Fluorescence on for Imaging Staphylococcus aureus Infection In Vivo
Authors: Xu Lingling , Zhan Wenjun , Deng Yu , Liu Xiaoyang , Gao Ge , Sun Xianbao , Liang Gaolin
Published: May 2022

Direct, noninvasive, and real‐time imaging of Staphylococcus aureus (S. aureus) infection is of great value for quick diagnosis of related disease in clinic, but remains challenging. Herein, employing a rationally designed near‐infrared fluorescence probe Cys(StB u)‐EDA‐Thioketal‐Lys(Cy5.5)‐CBT (TK‐CBT) and a CBT‐Cys click reaction, the fluorescence‐quenched nanoparticles TK‐CBT‐NPs are facilely prepared. Upon oxidation by the abundant reactive oxygen species in S. aureus‐infected macrophages, TK‐CBT‐NPs are fractured, turning the fluorescence “on” for imaging infections in vitro and in vivo. Specifically, TK‐CBT‐NPs show a 6.1‐fold fluorescence imaging signal enhancement of the macrophages that are infected by S. aureus for 20 h in vitro. At 4 h postinjection, TK‐CBT‐NPs show a 2.8‐fold fluorescence imaging signal enhancement of the sites in mice that are infected by S. aureus for 24 h. It is anticipated that TK‐CBT‐NPs could be applied for diagnosis of S. aureus infections in clinic in the near future.
Local Spin‐State Tuning of Iron Single‐Atom Electrocatalyst by S‐Coordinated Doping for Kinetics‐Boosted Ammonia Synthesis
Authors: Li Yan , Ji Yaxin , Zhao Yingjie , Chen Junxiang , Zheng Sixing , Sang Xiahan , Yang Bin , Li Zhongjian , Lei Lecheng , Wen Zhenhai , Feng Xinliang , Hou Yang
Published: May 2022

The electrochemical nitrogen reduction reaction (e‐NRR) is envisaged as alternative technique to the Haber–Bosch process for NH3 synthesis. However, how to develop highly active e‐NRR catalysts faces daunting challenges. Herein, a viable strategy to manipulate local spin state of isolated iron sites through S‐coordinated doping (FeSA‐NSC) is reported. Incorporation of S in the coordination of FeSA‐NSC can induce the transition of spin‐polarization configuration with the formation of a medium‐spin‐state of Fe (t2g6 eg1), which is beneficial for facilitating eg electrons to penetrate the antibonding π‐orbital of nitrogen. As a consequence, a record‐high current density up to 10 mA cm−2 can be achieved, together with a high NH3 selectivity of ≈10% in a flow cell reactor. Both experimental and theoretical analyses indicate that the monovalent Fe(I) atomic center in the FeSA‐NSC after the S doping accelerates the N2 activation and protonation in the rate‐determining step of *N2 to *NNH.
Interface Interaction Dependent Growth of Carbon Nanostructures: An In Situ Study
Authors: Zhang Xiaofang , Tian Dongliang , Yang Feng , Zhao Haofei , Lau Woon‐Ming , Wang Rongming
Published: May 2022

Controllable synthesis of carbon nanostructures is expected to achieve high electrical, optical, and mechanical performance for various applications. Despite great progress in this field, controllable synthesis of carbon nanostructures, i.e., graphite shells (GSs) and carbon nanotubes (CNTs), is still demanded to be deeply revealed. Here, a strategy is demonstrated to achieve GSs and bamboo CNTs by regulating the interface interaction via in situ pyrolysis of Co phthalocyanine (CoPc) in an environmental transmission electron microscopy (ETEM) at atomic resolution. The results indicate that the catalyst involves the nucleation, combination, and reconstruction of Co/Co3C, the growth modes of the carbon, i.e., base‐growth or tip‐growth, and nanostructures are dependent on the interface interaction between catalyst and substrate controlled by temperature. High temperature favors tip‐growth of bamboo CNTs with larger catalyst nanoparticles (NPs) (≈20 nm), while low temperature favors the base‐growth of GSs with smaller NPs (≈10 nm). The average growth rate of 131.3 nm s−1 at 850 °C is about 60 times compared with that at 750 °C. The work provides a comprehensive understanding of distinct growth mode of GSs and CNTs at different temperatures, which would be valuable for the controllable growth of carbon nanostructures by catalyst design and engineering.
Access to Nitrones from Amines via Electrocatalysis at Room Temperature
Authors: Shukla Gaurav , Yadav Dhananjay , Singh Saurabh , Shankar Singh Maya
Published: May 2022

A self‐enabled electrooxidative protocol for the synthesis of nitrones from bench stable amines has been developed under constant current electrolysis at room temperature, rendering metal and external oxidant‐free protocol in an alkaline medium. The electrocatalysis steps of reported strategy involve anodic oxidation of benzyl amines followed by cathodic reduction of nitro‐functional group in an undivided cell affording functional nitrones. The robustness of the electrocatalysis was reflected by tolerant substrate scope, oxidant‐free conditions, and an operationally friendly procedure. Moreover, the cyclic voltammetry and control experiment studies also support the electrochemical process in alkaline medium.

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Ru‐Catalyzed C−H Hydroxylation of Tyrosine‐Containing Di‐ and Tripeptides toward the Assembly of L‐DOPA Derivatives
Authors: Andrade‐Sampedro Paula , Matxain Jon M. , Correa Arkaitz
Published: May 2022

The development of catalytic tools for the late‐stage modification of amino acids within a peptide framework is a challenging task of capital importance. Herein, we report a Ru‐catalyzed C(sp2)−H hydroxylation of a collection of Tyr‐containing di‐ and tripeptides featuring the use of a carbamate as a removable directing group and PhI(OCOCF3)2 (PIFA) as oxidant. This air‐compatible tagging technique is reliable, scalable and provides access to L‐DOPA (L‐3,4‐dihydroxyphenylalanine) peptidomimetics in a racemization‐free fashion. Density Functional Theory calculations support a Ru(II)/Ru(IV) catalytic cycle.

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Transition‐Metal‐Free Radical Cyclization of 2‐Arylbenzoimidazoles with Unactivated AlkanesviaC(sp3)−H Functionalizations in Aqueous Media
Authors: Li Jiao‐Zhe , Mei Lan , Cai Xue‐Er , Zhang Can‐Can , Cao Ting‐Ting , Huang Xun‐Jie , Liu Yi‐Lin , Wei Wen‐Ting
Published: May 2022

Here we present a transition‐metal‐free radical cyclization of 2‐arylbenzoimidazoles with unactivated alkanes. By using di‐tert‐butyl peroxide (DTBP) to promote the C(sp3)−H bond functionalization, this approach enables assembly of various benzimidazo[2,1‐a]isoquinolin‐6(5H)‐ones in aqueous media. This strategy can not only well tolerate a wide range of cyclic alkanes, straight‐chain alkanes, toluene derivatives, as well as pharmaceutical molecule eudesmol, but also provides an approach for the functionalization of unactivated C(sp3)−H bonds in aqueous media under transition‐metal‐free systems.

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Super‐Resolution Vibrational Imaging Using Expansion Stimulated Raman Scattering Microscopy
Authors: Shi Lixue , Klimas Aleksandra , Gallagher Brendan , Cheng Zhangyu , Fu Feifei , Wijesekara Piyumi , Miao Yupeng , Ren Xi , Zhao Yongxin , Min Wei
Published: May 2022

Stimulated Raman scattering (SRS) microscopy is an emerging technology that provides high chemical specificity for endogenous biomolecules and can circumvent common constraints of fluorescence microscopy including limited capabilities to probe small biomolecules and difficulty resolving many colors simultaneously. However, the resolution of SRS microscopy remains governed by the diffraction limit. To overcome this, a new technique called molecule anchorable gel‐enabled nanoscale Imaging of Fluorescence and stimulated Raman scattering microscopy (MAGNIFIERS) that integrates SRS microscopy with expansion microscopy (ExM) is described. MAGNIFIERS offers chemical‐specific nanoscale imaging with sub‐50 nm resolution and has scalable multiplexity when combined with multiplex Raman probes and fluorescent labels. MAGNIFIERS is used to visualize nanoscale features in a label‐free manner with CH vibration of proteins, lipids, and DNA in a broad range of biological specimens, from mouse brain, liver, and kidney to human lung organoid. In addition, MAGNIFIERS is applied to track nanoscale features of protein synthesis in protein aggregates using metabolic labeling of small metabolites. Finally, MAGNIFIERS is used to demonstrate 8‐color nanoscale imaging in an expanded mouse brain section. Overall, MAGNIFIERS is a valuable platform for super‐resolution label‐free chemical imaging, high‐resolution metabolic imaging, and highly multiplexed nanoscale imaging, thus bringing SRS to nanoscopy.
Supra Hydrolytic Catalysis of Ni3Fe/rGO for Hydrogen Generation
Authors: Liu Jiangchuan , Zhang Mengchen , Tang Qinke , Zhao Yingyan , Zhang Jiguang , Zhu Yunfeng , Liu Yana , Hu Xiaohui , Li Liquan
Published: May 2022

Light metal hydrolysis for hydrogen supply is well suited for portable hydrogen fuel cells. The addition of catalysts can substantially aid Mg hydrolysis. However, there is a lack of clear catalytic mechanism to guide the design of efficient catalysts. In this work, the essential role of nanosized catalyst (Ni3Fe/rGO) in activating micro‐sized Mg with ultra‐rapid hydrolysis process is investigated for the first time. Here, an unprecedented content of 0.2 wt% Ni3Fe/rGO added Mg can release 812.4 mL g−1 hydrogen in just 60 s at 30 °C. Notably, an impressive performance with a hydrogen yield of 826.4 mL g−1 at 0 °C in only 30 s is achieved by the Mg‐2 wt% Ni3Fe/rGO, extending the temperature range for practical applications of hydrolysis. Moreover, the four catalysts (Ni3Fe/rGO, Ni3Fe, Ni/rGO, Fe/rGO) are designed to reveal the influence of composition, particle size, and dispersion on catalytic behavior. Theoretical studies corroborate that the addition of Ni3Fe/rGO accelerates the electron transfer and coupling processes and further provides a lower energy barrier diffusion path for hydrogen. Thus, a mechanism concerning the catalyst as migration relay is proposed. This work offers guidelines designing high‐performance catalysts especially for activating the hydrolysis of micro‐sized light weight metals.