bluuebunny/crossref_metadata_2025 huggingface dataset:
Phonological boundaries and the spectral center of gravity
Authors: Molis Michelle R. , Diehl Randy L. , Jacks Adam
Published: July 2002

A critical limit of 3–3.5 Bark has been reported for the ‘‘spectral center of gravity’’ effect between the second and third formants (F2 and F3) and is assumed to correspond to a perceptually natural boundary [A. K. Syrdal and H. S. Gopal, J. Acoust. Soc. Am. 79, 1086–1100 (1986)]. This hypothesis was tested for both the [+/−back] and [+/−coronal] distinctions in English vowels. Subjects identified two sets of three-formant synthetic vowels which varied orthogonally in F2 and F3 and ranged between /ᴜ/–/ɪ/ ([+/−back]) or /ɝ/–/ᴜ/ ([+/−coronal]). For the /ᴜ/–/ɪ/ distinction, a boundary shift was observed solely as a function of F2, ruling out an invariant F3–F2 boundary. For the /ɝ/–/ᴜ/ series, both F2 and F3 influenced boundary location. There was a relatively stable F3–F2 boundary for the mean identification responses in this case, but it occurred at less than the predicted 3–3.5 Bark difference. Follow-up results will also be presented. [Work supported by NIDCD.]
Controlled focused sonic booms from maneuvering aircraft
Authors: Downing Micah , Zamot Noel , Moss Chris , Morin Daniel , Wolski Ed , Chung Sukhwan , Plotkin Kenneth , Maglieri Domenic
Published: July 2002

In April 1994, the USAF Armstrong Laboratory, in cooperation with USAF Test Pilot School, conducted an experimental study of controlled focus boom generated by supersonic maneuvers. The objective of this study was to collect focus and postfocus booms and to assess the ability of aircrews to control the placement of the focal region during basic maneuvers. Forty-nine supersonic passes were flown and included level linear acceleration, level turn, accelerating dives, and climbout-pushover maneuvers. These flights were flown under calm and turbulent atmospheric conditions. Turbulent conditions had a defocusing effect which caused distortions in the focus region and resulted in smaller maximum overpressures. Sonic booms were collected by up to 25 boom event analyzer recorders (BEARs) placed in a 13 000-ft linear array. The BEAR units were spaced 500–2000 ft apart with the denser spacing at the expected focal region. This spacing was chosen to evaluate the thickness of both the focal and postfocal regions. The target location varied from 2000–5000 from the uptrack end of the array. Of the 49 flights, a focus boom was placed within the array 37 times and within ±3000 feet of the target point 27 times, demonstrating the ability to place controlled focus booms.
Sound absorption by an orifice plate in a flow duct
Authors: Wendoloski J. C.
Published: July 2002

In this paper the acoustic absorption due to an orifice plate in a duct supporting a mean flow is studied theoretically. Absorption takes place as the acoustic field energizes a vortex field which is generated at the orifice rim. A linearized approximation is made to the absorption mechanism. This work presents an analytical extension of Howe [Proc. R. Soc. London, Ser. A 366, 205–233 (1979)]. The latter deals with unsteady high Reynolds number flow through a circular aperture in a thin infinite screen. To the author’s knowledge, such an extension has not been previously made. The problem is formulated analytically insofar as it is possible and numerical results are presented. A Green’s function series expansion is used in the formulation. A difficulty arises with the convergence of this expansion. It is solved by a renormalization technique, which has been developed for this problem. The technique appears to be a novel method for dealing with convergence problems associated with term by term differentiation of Green’s function series expansions. To provide a check on the solution, it is shown that when the radius of the duct tends to infinity the present expression for the Rayleigh conductivity of the orifice plate limits to the expression obtained by Howe for an aperture in a thin infinite screen. With respect to the numerical results, it appears that for orifice mean flow Mach numbers ≲0.2, an orifice to duct open area ratio of 0.3 provides near optimal average absorption, for the band of frequencies limited by the first symmetric mode cutoff frequency.
Estimation of the elastic constants of a cylinder with a length equal to its diameter
Authors: Nieves F. J. , Gascón F. , Bayón A.
Published: July 2002

A simple and noncomputational intensive method is proposed for elastically characterizing an isotropic material. The Poisson’s ratio and the shear modulus are determined from the axisymmetric vibrations of a cylinder with a length equal to its diameter. These vibrations are excited by means of a wide spectrum impact. The optical system used allows the simultaneous detection of several vibration modes. The out-of-plane displacement is detected by speckle interferometry. From the resulting vibration displacement spectrum, the two lowest frequencies are obtained, both corresponding to axisymmetric modes—specifically, the first symmetric mode and the first antisymmetric mode. The values of both dynamic elastic constants are obtained by comparing previously computed nondimensional natural frequencies and the measured frequencies. The method requires only one experiment and needs no electronic computation. The results obtained for an aluminum cylinder are coherent and confirm the appropriateness of the method. The relative difference between the Young’s modulus values calculated by the proposed method and applying the elementary theory to a long rod of the same material is 0.27%. Comparing the shear modulus value obtained by this method and the calculated one from the lower frequency in torsion, a relative difference of 4.6% is found.
Variable-duration notched-noise experiments in a broadband noise context
Authors: Hant James J. , Strope Brian P. , Alwan Abeer A.
Published: July 2002

A variable-duration notched-noise experiment was conducted in a noise context. Broadband noise preceded and followed a tone and notched noise of similar duration. Thresholds were measured at four durations (10, 30, 100, and 300 ms), two center frequencies (0.6, 2.0 kHz), and five relative notch widths (0.0, 0.1, 0.2, 0.4, 0.8). At 0.6 kHz, 10-ms thresholds decrease 6 dB across notch widths, while 300-ms thresholds decrease over 35 dB. These trends are similar but less pronounced at 2 kHz. In a second experiment, the short-duration notched noise was replaced with a flat noise which provided an equivalent amount of simultaneous masking and thresholds dropped by as much as 20 dB. A simple combination of simultaneous and nonsimultaneous masking is unable to predict these results. Instead, it appears that the elevated thresholds at short durations are dependent on the spectral shape of the simultaneous masker.
Silicon cochlea: A digital VLSI implementation of a quantitative model of the auditory system
Authors: Brucke Matthias , Nebel Wofgang , Schwarz Alexander , Mertsching Bärbel , Hansen Martin , Kollmeier Birger
Published: July 2002

In this paper a digital VLSI implementation of a quantitative model of the auditory system is presented, which includes several processing stages physiologically and psychoacoustically motivated by the function of the human ear. The model was successfully applied to a wide range of applications from psychoacoustical experiments to speech recognition. The hardware design is derived from a C/C++ notation of the algorithms using floating point arithmetics. One application of the model is used to determine the necessary internal precision of the computations for a transfer into a version suitable for a hardware implementation using fixpoint arithmetics. This application provides a very valid test bench since the significant speech processing features of the model are proofed by computing an objective speech quality measure. The processing scheme is divided into designs for two FPGAs and will be converted into ASICs in a later version. The implementation of the model as dedicated hardware provides efficient coprocessing power and allows implementations of complex auditory-based speech processing algorithms in real time because the chipset performs substantial parts of the necessary calculations.
Variational formulation using integral equations to solve sound scattering above an absorbing plane
Authors: Granat C. , Tahar M. Ben , Ha-Duong T.
Published: July 2002

The boundary element method is used to model two-dimensional acoustic radiation and scattering from a body of arbitrary shape above an infinite plane of flat surface and homogeneous impedance. The particularity of the study is the use of an indirect integral representation of the solution, given in terms of the jumps of pressure and its normal derivative through the boundaries. A variational formulation is associated with the boundary indirect integral equations modeling our problem. The major difficulty in the formulation is the infinite feature of the plane, which is avoided by introducing an appropriate Green’s function. Numerical results of the attenuation of sound by noise barriers are presented. They show good agreement with other results in the literature.
Modeling acousto-elastic waveguide/object scattering with the Rayleigh hypothesis
Authors: Fawcett J. A.
Published: July 2002

In this paper the plane-wave scattering matrices for a range-dependent seabed and upper free surface are computed using the Rayleigh hypothesis at the surfaces. These matrices can then be used to compute the pressure field within a waveguide bounded by these surfaces; they can also be easily combined with the scattering matrix characterizing an object. Computational examples are given for range-dependent acousto-elastic waveguides and the fields compared with those computed by other methods. An example with a steel cylinder in the waveguide is also shown.
Adaptive matched beam processing for source localization
Authors: Yoo Kwang , Yang T. C.
Published: July 2002

Matched beam processing (MBP) has been previously applied to a horizontal line array for localizing a moving source in bearing and range, and for differentiating a submerged target from a surface clutter [T. C. Yang and T. Yates, J. Acoust. Soc. Am. 104 (1998)]. MBP is matched field processing in the beam domain. Using the Bartlett processor, bearing and depth resolutions are often inadequate for rejecting surface clutter and other noise sources. High-resolution processors may be required. We note that in situations where many clutters exist, adaptive (plane-wave) beamforming has effectively rejected clutter by either high-angular resolution or by steering a null to the interference source. Motivated by this approach, an adaptive MBP will be investigated in this paper. The new processor will apply adaptive beamforming to the data and replica fields such that interference has already been removed before the matched field correlation. This approach differs from the adaptive matched field processing where interference remains in the data field. The latter approach is known to be sensitive to environmental mismatch, as a result the correlation between the replica and the interference fields may be present as substantial clutter. Initial numerical results will be presented using simulated data with interference sources. [Work supported by the Office of Naval Research.]
Preference judgments of artificial processed and hearing-aid transduced speech
Authors: Versfeld Niek J. , Festen Joost M. , Houtgast Tammo
Published: July 2002

In order to assess the relative importance of various signal processing algorithms and distortions on hearing-aid preference, male and female speech was manipulated in a number of ways and subsequently presented to normal-hearing and hearing-impaired subjects (the latter having a mild sensorineural high-frequency hearing loss). Signal manipulations were artificial (e.g., filtering, compression, peak clipping, or adding noise) or were actual dummy-head recordings of five different hearing aids. Listeners judged the sounds in a pairwise-comparison format. Their task was to indicate the “hearing aid” they would prefer assuming they had to wear it all day. The data were analyzed with multidimensional scaling techniques; Principal Components Analysis revealed that the first two dimensions on which preference judgments were based, can be interpreted as (1) intelligibility or clarity, and (2) distinction between signal distortion and added background distortion. Furthermore, the results showed that normal-hearing subjects generally preferred the original signal, whereas hearing-impaired subjects were inclined to choose the signals with a high-frequency emphasis. Severe band-pass filtering or low-frequency emphasis were disliked, as was to be expected. Surprisingly, however, a soft background noise (S/N ratio of 25 dB) was often among the least preferred of all signals. The differences in preference between the five hearing aids were small, but consistent. For hearing-impaired subjects, hearing-aid ordering could be accounted for by the amount of low-frequency cutoff; for normal-hearing subjects both high- and low-frequency cutoff played a role. Results of a retest experiment with normal-hearing subjects, about one year later, showed that subjects’ criteria remain remarkably stable.
Analysis of high-frequency acoustic scattering data measured in the shallow waters of the Florida Strait
Authors: Rogers Andrew K. , Yamamoto Tokuo
Published: July 2002

Experiments were conducted in the Florida Strait region of the United States in July 1995 to investigate the contribution of sediment volume scattering to measured acoustic backscatter levels at frequencies of 7.5 and 15 kHz. Five sites were analyzed for bottom backscattering level in the radial and azimuthal directions. Sediment geophysical parameters were established by a cross-well tomographic measurement and used as inputs for modeling. Both sediment volume and rough interface scattering models were utilized in analyzing the data. Comparison of model predictions with measured data showed that for grazing angles, at the water–sediment interface, from the critical angle to approximately 60 degrees, volume scattering dominated. For angles greater than approximately 60 degrees, surface roughness scattering consistently dominated. In geographic areas where the interface sound speed ratio exceeded one, roughness scattering controled the backscattered level for grazing angles less than the critical angle. Inversion of the measured acoustic backscatter data was performed using a genetic algorithm optimization developed for use with the volume scattering model. Inversion results were found to agree well with measured data and measured environmental parameters that describe the scattering volume.
Feedback control of structurally radiated sound into enclosed spaces using structural sensing
Authors: Griffin Steven , Hansen Colin , Cazzolato Ben
Published: July 2002

A technique is developed that addresses sensor and actuator placement and feedback control of structural/acoustic problems that can be described as a flexible structure surrounding an acoustic cavity. Specifically, this work is directed at the space launch vehicle problem, where it is assumed that it is not possible to obtain, in advance of a required control output, a coherent measurement of the disturbance or to directly measure the quantity to be controlled. These assumptions necessitate the use of structural sensing to predict the sound pressure in the cavity and of feedback control to reduce the radiated sound. A method for selecting sensor and actuator positions based on a transformation of the problem into radiation modes is covered as well as an optimal feedback control approach which allows the control of radiated pressure into a defined subvolume of the cavity using only structural actuators and sensors. Finally, an example problem is completed which draws on all of the theoretical development to suppress radiated sound within a subvolume.
Computation of transient radiation in semi-infinite regions based on exact nonreflecting boundary conditions and mixed time integration
Authors: Thompson Lonny L. , Huan Runnong
Published: July 2002

Transient radiation in a semi-infinite region, bounded by a planar infinite baffle with a local acoustic source is considered. The numerical simulation of the transient radiation problem requires an artificial boundary Γ, here chosen to be a hemisphere, which separates the computational region from the surrounding unbounded acoustic medium. Inside the computational region we use a semidiscrete finite element method. On Γ, we apply the exact nonreflecting boundary condition (NRBC) first derived by Grote and Keller for the free-space problem. Since the problem is symmetric about the infinite planar surface, in order to satisfy the rigid baffle condition it is sufficient to restrict the indices in the spherical harmonic expansion which defines the NRBC and scale the radial harmonics which drive auxiliary equations on the boundary. The Fourier expansion in the circumferential angle appearing in the NRBC may be used to efficiently model axisymmetric problems in two dimensions. A new mixed explicit-implicit time integration method which retains the efficiency of explicit pressure field updates without the need for diagonal matrices in the auxiliary equations on Γ is presented. Here, the interior finite element equations are integrated explicitly in time while the auxiliary equations are integrated implicitly. The result is a very natural and highly efficient algorithm for large-scale wave propagation analysis. Numerical examples of fully transient radiation resulting from a piston transducer mounted in an infinite planar baffle are compared to analytical solutions to demonstrate the accuracy of the mixed time integration method with the NRBC for the half-space problem.
Two-dimensional effects in the edge sound of vortices and dipoles
Authors: Schouten G.
Published: July 2002

Edge sound consists of the pressure waves generated by the fast modification of the local velocity field when a flow inhomogeneity passes near an edge. The modifications take place in the near field; they locally allow a description in terms of incompressible flow. The incompressible disturbances are referred to as pseudosound. The disturbances progress into the far field as diffraction waves that, in 3D space, dominate the pseudosound. In 3D space the diffraction waves have a 2D character in their time history; they behave as the halfth time derivative of the pseudosound. This latter effect is not manifest in the analogous, purely 2D diffraction problem where the diffracted wave in the far field has the form of retarded pseudosound. In this paper, an answer is presented to the intriguing question: what is the rationale behind this difference in behavior? The analysis is based on time integral representations having as a kernel the closed form of Green’s functions for half-plane problems in 2D and in 3D space. The Green’s functions are presented in this paper. The integral representations inherently represent the relations between wave-sound and incompressible pseudosound. After performing an integration by parts, appropriate approximations reveal the incompressible near-field behavior or the far-field wave behavior. Examples are given of the edge sound of moving vortices and dipoles in 2D and in 3D space. In free 2D space the potential field of a vortex is proportional to the logarithm of the distance; the field of a dipole is proportional to the inverse of the distance. However, the edge sound pressure of vortices and of dipoles does not show a difference in far field behavior. It falls off with the square root of distance in 2D space and linear with distance in 3D space.
Determination of parameters for lumped parameter models of the vocal folds using a finite-element method approach
Authors: de Vries M. P. , Schutte H. K. , Verkerke G. J.
Published: July 2002

To study the mechanical behavior of the vocal folds, lumped parameter models of the vocal folds have been developed in the past. Coupling with a model of the aerodynamics in the glottis provides the possibility of simulating glottal waves. A new method is presented to obtain values for the masses and springs of the lumped parameter models by using a finite-element method model of the vocal folds. This finite-element method model is based on geometry and material data from the literature, resulting in a model that describes the vocal fold in a realistic way. Requiring the dynamic behavior of the lumped parameter model of the vocal fold to be equal to the dynamic behavior of the finite-element method model of the vocal fold, parameter values are obtained that are purely based on dynamic considerations. Therefore, the behavior of the vocal folds is described in a realistic way by these parameters. These values are compared with the values used by previous authors and are implemented in lumped parameter models. Self-sustained oscillation is achieved with the new values for masses and springs.
A macro-mechanical model of the guinea pig cochlea with realistic parameters
Authors: Brass David
Published: July 2002

The post-mortem transfer function of the cochlea of the guinea pig was compared to the transfer function generated by a model with parameters derived from physical measurements of the guinea pig cochlea. Both the formulation and parameters of the model were carefully chosen to be realistic using evidence from published measurements. The fit between the transfer function of the model and recent mechanical measurements of the passive guinea pig cochlear response was good, with a root mean square ratio of 6.3 dB in amplitude and 0.33π rad in phase. The model was used to explore the effect of cochlear partition mode factor and duct geometry upon the mechanical response of the cochlea. Possible inadequacies of the model which could explain the remaining differences between the output of the model and measurements are discussed.
Enhancement of the edges of temporal masking functions by complex patterns of overshoot and undershoot
Authors: Formby C. , Sherlock L. P. , Ferguson S. H.
Published: July 2002

The purpose of this report is to present new data that provide a novel perspective on temporal masking, different from that found in the classical auditory literature on this topic. Specifically, measurement conditions are presented that minimize rather than maximize temporal spread of masking for a gated (200-ms) narrow-band (405-Hz-wide) noise masker logarithmically centered at 2500 Hz. Masked detection thresholds were measured for brief sinusoids in a two-interval, forced-choice (2IFC) task. Detection was measured at each of 43 temporal positions within the signal observation interval for the sinusoidal signal presented either preceding, during, or following the gating of the masker, which was centered temporally within each 500-ms observation interval. Results are presented for three listeners; first, for detection of a 1900-Hz signal across a range of masker component levels (0–70 dB SPL) and, second, for masked detection as a function of signal frequency (fs=500–5000 Hz) for a fixed masker component level (40 dB SPL). For signals presented off-frequency from the masker, and at low-to-moderate masker levels, the resulting temporal masking functions are characterized by sharp temporal edges. The sharpness of the edges is accentuated by complex patterns of temporal overshoot and undershoot, corresponding with diminished and enhanced detection, respectively, at both masker onset and offset. This information about the onset and offset timing of the gated masker is faithfully represented in the temporal masking functions over the full decade range of signal frequencies (except for fs=2500 Hz presented at the center frequency of the masker). The precise representation of the timing information is remarkable considering that the temporal envelope characteristics of the gated masker are evident in the remote masking response at least two octaves below the frequencies of the masker at a cochlear place where little or no masker activity would be expected. This general enhancement of the temporal edges of the masking response is reminiscent of spectral edge enhancement by lateral suppression/inhibition.
Distance judgments of nearby sources in a reverberant room: Effects of stimulus envelope
Authors: Santarelli Scott G. , Kopčo Norbert , Shinn-Cunningham Barbara G.
Published: July 2002

Localization was measured for nearby sources with abrupt or slow rise/fall times in a reverberant space. A recent model of distance perception [A. W. Bronkhorst and T. Houtgast, Nature 397, 517–520 (1999)] suggests that perceived distance is computed from the room impulse response. The model assumes that energy in the onset of the impulse response (primarily from the direct sound, varying with distance) is compared to late energy (primarily from the reverberation, roughly independent of distance). However, other results suggest that subjects are poor at deconvolving transfer function and sound source characteristics [Rakerd et al., J. Acoust. Soc. Am. 106, 2812–2820 (1999)]. Taken together, these results suggest that subjects cannot use the transfer function, but estimate source distance from some statistic closely related to that proposed in the model (e.g., the ratio of initial to late energy in the total waveform at the ear). For impulsive sounds, such a simpler statistic yields results similar to those of the model; however, distance judgments would be significantly degraded for sources with slow onsets. However, subjects were equally good at judging distance, independent of characteristics of the stimulus envelope. [Work supported in part by AFOSR Grant No. F49620-98-1-0108.]
Vibration characteristics of pipe organ reed tongues and the effect of the shallot, resonator, and reed curvature
Authors: Plitnik G. R.
Published: July 2002

Pipe organ reed pipes sound when a fixed-free curved brass reed mounted on a shallot connected to a resonator is forced to vibrate by an impressed static air pressure. Five sets of experiments were performed in order to investigate the influence of the most important parameters which could affect the tone of a reed pipe. First, the phase difference between the pressure variation in the shallot and the boot, and its relationship to the motion of the reed tongue were analyzed to compare their phases and their spectra. Next, the frequency dependence of the reed on three basic parameters (reed thickness, its vibrating length, and the imposed static air pressure) was investigated in an attempt to determine an empirical equation for the frequency. For each trial, two of the variables were kept constant while the third was altered in order to construct an equation giving frequency as a function of the three variables. Third, experiments were conducted using three different types of shallots: the American (or English) style, the French style, and the German style. The results show that for each shallot, the frequency increases linearly with thickness and linearly with air pressure (over the normal operating range of the reed). For each of the shallots, frequency varies inversely with length when the other variables are held constant. The effect on the reed spectrum of using the three different types of shallot was also investigated, as was the effect of reducing the interior volume of each type. Progressively filling the shallot interior generally decreases the frequency of the vibrating reed. The effect of the resonators on frequency and spectrum was studied because the resonator is an integral part of the resulting tone; virtually every reed stop has some type of resonator. The resonator tends to raise the Q of the impedance peaks and reduce the fundamental frequency. Finally, the influence of the type and degree of curvature on reed vibration was briefly examined; increasing the reed curvature tends to decrease the vibration frequency and increase the sound intensity by creating a richer spectrum.
Fourier Transform Method in Linear Viscoelastic Analysis: The Vibrating Viscoelastic Reed
Authors: Wapner Phillip G. , Forsman W. C.
Published: July 2002

When linear viscoelasticity is formulated in a Fourier transform space, it is not necessary to assume any specific mathematical model, such as assemblies of Voigt or Maxwell elements, or differential operator equations, to completely describe the behavior of linear viscoelastic materials under any stress-strain history. Indeed, the Fourier transform method is quite applicable even for complex vibration problems. In this paper we apply the method to the vibrating viscoelastic reed under two modes of oscillation, fixed at one end and subjected to a sinusoidal loading at the other, and subjected to a sinusoidal force at one end with the other end left free to oscillate. Theoretical results were in excellent quantitative agreement with experiments performed on a reed of poly(t-butyl ethylene oxide) using both modes of excitation. We expressed the results in terms of corrections to the approximate relationship tan δ=(bandwidth)/(resonance frequency).
A Readily Scalable, Clinically Demonstrated, Antibiofouling Zwitterionic Surface Treatment for Implantable Medical Devices
Authors: McVerry Brian , Polasko Alexandra , Rao Ethan , Haghniaz Reihaneh , Chen Dayong , He Na , Ramos Pia , Hayashi Joel , Curson Paige , Wu Chueh‐Yu , Bandaru Praveen , Anderson Mackenzie , Bui Brandon , Sayegh Aref , Mahendra Shaily , Carlo Dino Di , Kreydin Evgeniy , Khademhosseini Ali , Sheikhi Amir , Kaner Richard B.
Published: March 2022

Unlike growth on tissue, microbes can grow freely on implantable devices with minimal immune system intervention and often form resilient biofilms that continuously pump out pathogenic cells. The efficacy of antibiotics used to treat infection is declining due to increased rates of pathogenic resistance. A simple, one‐step zwitterionic surface modification is developed to significantly reduce protein and microbial adhesion to synthetic materials and demonstrate the successful modification of several clinically relevant materials, including recalcitrant materials such as elastomeric polydimethylsiloxane. The treated surfaces exhibit robust adhesion resistance against proteins and microorganisms in both static and flow conditions. Furthermore, the surface treatment prevents the adhesion of mammalian fibroblast cells while displaying no cytotoxicity. To demonstrate the clinical efficacy of the novel technology in the real‐world, a surface‐treated, commercial silicone foley catheter is developed that is cleared for use by the U.S. Food and Drug Administration (K192034). 16 long‐term catheterized patients received surface‐treated catheters and completed a Patient Global Impression of Improvement (PGI‐I) questionnaire. 10 out of 16 patients described their urinary tract condition post implantation as “much better” or “very much better” and 72% (n = 13) of patients desire to continue using the surface‐treated catheter over conventional latex or silicone catheters.
Enhancing the Reversibility of Lattice Oxygen Redox Through Modulated Transition Metal–Oxygen Covalency for Layered Battery Electrodes
Authors: Cheng Chen , Chen Chi , Chu Shiyong , Hu Haolv , Yan Tianran , Xia Xiao , Feng Xuefei , Guo Jinghua , Sun Dan , Wu Jinpeng , Guo Shaohua , Zhang Liang
Published: March 2022

Utilizing reversible lattice oxygen redox (OR) in battery electrodes is an essential strategy to overcome the capacity limitation set by conventional transition metal redox. However, lattice OR reactions are often accompanied with irreversible oxygen oxidation, leading to local structural transformations and voltage/capacity fading. Herein, it is proposed that the reversibility of lattice OR can be remarkably improved through modulating transition metal–oxygen covalency for layered electrode of Na‐ion batteries. By developing a novel layered P2‐Na0.6Mg0.15Mn0.7Cu0.15O2 electrode, it is demonstrated that the highly electronegative Cu dopants can improve the lattice OR reversibility to 95% compared to 73% for Cu‐free counterpart, as directly quantified through high‐efficiency mapping of resonant inelastic X‐ray scattering. Crucially, the large energetic overlap between Cu 3d and O 2p states dictates the rigidity of oxygen framework, which effectively mitigates the structural distortion of local oxygen environment upon (de)sodiation and leads to the enhanced lattice OR reversibility. The electrode also exhibits a completely solid‐solution reaction with an ultralow volume change of only 0.45% and a reversible metal migration upon cycling, which together ensure the improved electrochemical performance. These results emphasize the critical role of transition metal–oxygen covalency for enhancing the reversibility of lattice OR toward high‐capacity electrodes employing OR chemistry.
Strain Adjustment Realizes the Photocatalytic Overall Water Splitting on Tetragonal Zircon BiVO4
Authors: Dai Dujuan , Liang Xizhuang , Zhang Beibei , Wang Yuanyuan , Wu Qian , Bao Xiaolei , Wang Zeyan , Zheng Zhaoke , Cheng Hefeng , Dai Ying , Huang Baibiao , Wang Peng
Published: March 2022

Overall water splitting to generate H2 and O2 is vital in solving energy problem. It is still a great challenge to seek efficient visible light photocatalyst to realize overall water splitting. In this work, the tetragonal zircon BiVO4 is prepared by epitaxial growth on FTO substrate and its overall water splitting reaction is studied. Under the influence of epitaxial strain, the conduction band position shifts negatively and beyond H+/H2 reduction potential (0 V vs NHE), which enables it to possess the photocatalytic hydrogen evolution activity. After loading cocatalysts, the overall water splitting (λ > 400 nm) is realized (H2: ≈65.7 µmol g−1 h−1, O2: ≈32.6 µmol g−1 h−1), and the value of solar hydrogen conversion efficiency is 0.012%. The single‐particle photoluminescence (PL) spectra and PL decay kinetics tests demonstrate the cocatalysts are beneficial to the separation and transfer of carriers. The new strategy of adjusting the band structure by strain is provided.
Multifunctional π‐Conjugated Additives for Halide Perovskite
Authors: Lao Yinan , Yang Shuang , Yu Wenjin , Guo Haoqing , Zou Yu , Chen Zhijian , Xiao Lixin
Published: March 2022

Additive is a conventional way to enhance halide perovskite active layer performance in multiaspects. Among them, π‐conjugated molecules have significantly special influence on halide perovskite due to the superior electrical conductivity, rigidity property, and good planarity of π‐electrons. In particular, π‐conjugated additives usually have stronger interaction with halide perovskites. Therefore, they help with higher charge mobility and longer device lifetime compared with alkyl‐based molecules. In this review, the detailed effect of conjugated molecules is discussed in the following parts: defect passivation, lattice orientation guidance, crystallization assistance, energy level rearrangement, and stability improvement. Meanwhile, the roles of conjugated ligands played in low‐dimensional perovskite devices are summarized. This review gives an in‐depth discussion about how conjugated molecules interact with halide perovskites, which may help understand the improved performance mechanism of perovskite device with π‐conjugated additives. It is expected that π‐conjugated organic additives for halide perovskites can provide unprecedented opportunities for the future improvement of perovskite devices.
In Situ Visualization and Quantification of Electrical Self‐Heating in Conjugated Polymer Diodes Using Raman Spectroscopy
Authors: Maity Sudeshna , Ramanan Charusheela , Ariese Freek , MacKenzie Roderick C. I. , von Hauff Elizabeth
Published: March 2022

Self‐heating in organic electronics can lead to anomalous electrical performance and even accelerated degradation. However, in the case of disordered organic semiconductors, self‐heating effects are difficult to quantify using electrical techniques alone due to complex transport properties. Therefore, more direct methods are needed to monitor the impact of self‐heating on device performance. Here, self‐heating in poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta [2,1‐b;3,4‐b′] dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)] (PCPDTBT) diodes is visualized using Raman spectroscopy, and thermal effects due to self‐heating are quantified by exploiting temperature‐dependent shifts in the polymer vibrational modes. The temperature increases due to self‐heating are quantified by correlating the Raman shifts observed in electrically biased diodes with temperature‐dependent Raman measurements. Temperature elevations up to 75 K are demonstrated in the PCPDTBT diodes at moderate power of about 2.6–3.3 W cm−2. Numerical modeling rationalizes the significant role of Joule and recombination heating on the diode current–voltage characteristics. This work demonstrates a facile approach for in situ monitoring of self‐heating in organic semiconductors for a range of applications, from fundamental transport studies to thermal management in devices.
Challenges to voluntary Ag carbon markets
Authors: Wongpiyabovorn Oranuch , Plastina Alejandro , Crespi John M.
Published: March 2022

The credibility of agricultural carbon credits will play a critical role in the determination of payments received by farmers through voluntary carbon markets. This article analyzes the major challenges from both the demand and supply sides to voluntary agricultural carbon credit programs and serves as a resource to researchers, producers, policymakers, and other stakeholders who seek a comprehensive analysis of the challenges that still face this market despite recent positive developments in global agreements.
Novel finding of lissencephaly and severe osteopenia in a Chinese patient with SATB2‐associated syndrome and a brief review of literature
Authors: Lo Hui‐Yin , Ng Wai‐Fu , Fong Nai‐Chung , Lui Choi‐Yu Dilys , Lam Ching‐Wan
Published: March 2022

SATB2‐associated syndrome (SAS) is a rare disorder characterized by developmental delay, behavioral problems, and craniofacial anomalies in particular dental and palatal abnormalities. We describe the clinical course, genetic and autopsy findings in a Chinese boy with global developmental delay, hypotonia, epilepsy, recurrent fractures and osteopenia. Brain magnetic resonance imaging showed pachygyria, white matter hypoplasia and hypogenesis of the corpus callosum. Whole‐exome sequencing identified a novel heterozygous missense variant c.1555G>A p.(Glu519Lys) in the SATB2 gene. Unfortunately, he died at 26 months of bronchiolitis and pneumonia. Autopsy revealed pachygyria which was more severe anteriorly, dilated lateral and third ventricles and partial agenesis of the corpus callosum. Histology showed features compatible with two‐layered lissencephaly. The bone showed disordered lamination and bone matrix. Although SATB2 has been shown to be involved in the regulation of neuronal migration in the developing brain, lissencephaly has not been reported so far. This could represent a more severe phenotype of SAS.
High‐Resolution NMR H/D Exchange of Human Superoxide Dismutase Inclusion Bodies Reveals Significant Native Features Despite Structural Heterogeneity
Authors: Naser Dalia , Tarasca Michael V. , Siebeneichler Bruna , Schaefer Anna , Deol Harmeen K. , Soule Tyler G. B. , Almey Johnathan , Kelso Susan , Mishra Gyana G. , Simon Hilary , Meiering Elizabeth M.
Published: March 2022

Protein aggregation is central to aging, disease and biotechnology. While there has been recent progress in defining structural features of cellular protein aggregates, many aspects remain unclear due to heterogeneity of aggregates presenting obstacles to characterization. Here we report high‐resolution analysis of cellular inclusion bodies (IBs) of immature human superoxide dismutase (SOD1) mutants using NMR quenched amide hydrogen/deuterium exchange (qHDX), FTIR and Congo red binding. The extent of aggregation is correlated with mutant global stability and, notably, the free energy of native dimer dissociation, indicating contributions of native‐like monomer associations to IB formation. This is further manifested by a common pattern of extensive protection against H/D exchange throughout nine mutant SOD1s despite their diverse characteristics. These results reveal multiple aggregation‐prone regions in SOD1 and illuminate how aggregation may occur via an ensemble of pathways.
N‐Heterocyclic Carbene Based Nanolayer for Copper Film Oxidation Mitigation
Authors: Berg Iris , Amit Einav , Hale Lillian , Toste F. Dean , Gross Elad
Published: March 2022

The wide use of copper is limited by its rapid oxidation. Main oxidation mitigation approaches involve alloying or surface passivation technologies. However, surface alloying often modifies the physical properties of copper, while surface passivation is characterized by limited thermal and chemical stability. Herein, we demonstrate an electrochemical approach for surface‐anchoring of an N‐heterocyclic carbene (NHC) nanolayer on a copper electrode by electro‐deposition of alkyne‐functionalized imidazolium cations. Water reduction reaction generated a high concentration of hydroxide ions that induced deprotonation of imidazolium cations and self‐assembly of NHCs on the copper electrode. In addition, alkyne group deprotonation enabled on‐surface polymerization by coupling surface‐anchored and solvated NHCs, which resulted in a 2 nm thick NHC‐nanolayer. Copper film coated with a NHC‐nanolayer demonstrated high oxidation resistance at elevated temperatures and under alkaline conditions.
Dissipative Control over the Toehold‐Mediated DNA Strand Displacement Reaction
Authors: Del Grosso Erica , Irmisch Patrick , Gentile Serena , Prins Leonard J. , Seidel Ralf , Ricci Francesco
Published: March 2022

Here we show a general approach to achieve dissipative control over toehold‐mediated strand‐displacement, the most widely employed reaction in the field of DNA nanotechnology. The approach relies on rationally re‐engineering the classic strand displacement reaction such that the high‐energy invader strand (fuel) is converted into a low‐energy waste product through an energy‐dissipating reaction allowing the spontaneous return to the original state over time. We show that such dissipative control over the toehold‐mediated strand displacement process is reversible (up to 10 cycles), highly controllable and enables unique temporal activation of DNA systems. We show here two possible applications of this strategy: the transient labelling of DNA structures and the additional temporal control of cascade reactions.
Thickness‐dependent high‐performance solid oxide fuel cells with Ba0.5Sr0.5Co0.8Fe0.2O3‐δ cathode
Authors: Qiu Hao , Jiang Shanshan , Niu Yingjie , Zhang Qi , Pang Yingping , Su Chao
Published: March 2022

The electrochemical performance of solid oxide fuel cells (SOFCs) is highly reliant upon the properties of cathodes, including crystal structure, electrical conductivity, electrode thickness, and so on. Here, Ba0.5Sr0.5Co0.8Fe0.2O3‐δ (BSCF) is synthesized and served as the electrode for enabling high‐performance SOFCs. The effect of electrode thickness on the electrocatalytic activity is systematically investigated. The electrode thickness is adjusted in two ways. One is spray‐coating and then calcining once, and the other is performing the above process twice. On the basis of symmetrical cells configuration, the oxygen reduction reaction (ORR) activity of BSCF electrode with different thickness is evaluated and analyzed by the electrochemical impedance spectroscopy (EIS) technique and distribution of relaxation time (DRT). The obtained area‐specific resistances (ASRs) of electrodes on the oxygen ion conducting electrolyte Sm0.2Ce0.9O1.90 (SDC) demonstrate the thickness‐dependent electrochemical activity in ORR of BSCF electrode. With an electrode thickness of 24 μm that controlled by conducting “spray‐coating and calcining” twice, the BSCF electrode displays the optimal electrochemical performance with an ASR of 0.072 Ω cm2 in ambient air at 600°C. This strategy has allowed us to produce an electrode layer with optimal thickness, paving a new path for the design of high‐performance SOFCs.
2‐(N‐3‐Sulfopropyl‐N,N‐dimethyl ammonium)ethyl methacrylate modified graphene oxide embedded into cellulose acetate ultrafiltration membranes for improved performance
Authors: Xabela Sinethemba , Moutloali Richard Motlhaletsi
Published: March 2022

N‐(3‐sulfopropyl)‐N‐(methacryloxyethyl)‐N,N‐dimethylammonium betaine (SBMA) modified graphene oxide composite used as a filler in the fabrication of a nanocomposite cellulose acetate membrane was grafted through reverse atom transfer radical polymerization (RATRP) technique from a GO‐Br precursor. All the prepared materials (GO, GO‐Br, PSBMA@GO) were characterized using a combination of FTIR, BET, TEM, TGA, RAMAN, and XRD. The effect of different GO and PSBMA@GO contents on cellulose acetate membranes was investigated using AFM, contact angle measurements and SEM techniques. The surface hydrophilicity of the fabricated membranes increased with increasing content of PSBMA@GO filler through the water contact angle method. The relative flux of the base membrane at 900 kPa was 66.6 L.m−2.h−1 compared to that of PSBMA@GO composite membrane (0.5 wt%) at 117.67 L.m−2.h−1. The addition of the PSBMA@GO composites resulted in increased fouling resistance with high‐flux recovery (93%) and low‐overall flux decrease ratios (0.01%). Furthermore, nanocomposite membranes exhibited higher dye rejections for Congo Red (CR, 99.1% hence confirming their UF nature), methyl orange (MO, 84.2%) and methylene blue (MB, 95.3%) dyes compared with unmodified CA membranes. Overall, these nanocomposite membranes showed promising properties as potential candidates for dye removal in textile wastewater.
The 2021 European Alliance of Associations for Rheumatology/American College of Rheumatology Points to Consider for Diagnosis and Management of Autoinflammatory Type I Interferonopathies:CANDLE/PRAAS,SAVI, andAGS
Authors: Cetin Gedik Kader , Lamot Lovro , Romano Micol , Demirkaya Erkan , Piskin David , Torreggiani Sofia , Adang Laura A. , Armangue Thais , Barchus Kathe , Cordova Devon R. , Crow Yanick J. , Dale Russell C. , Durrant Karen L. , Eleftheriou Despina , Fazzi Elisa M. , Gattorno Marco , Gavazzi Francesco , Hanson Eric P. , Lee‐Kirsch Min Ae , Montealegre Sanchez Gina A. , Neven Bénédicte , Orcesi Simona , Ozen Seza , Poli M. Cecilia , Schumacher Elliot , Tonduti Davide , Uss Katsiaryna , Aletaha Daniel , Feldman Brian M. , Vanderver Adeline , Brogan Paul A. , Goldbach‐Mansky Raphaela
Published: March 2022

Objective

Autoinflammatory type I interferonopathies, chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature/proteasome‐associated autoinflammatory syndrome (CANDLE/PRAAS), stimulator of interferon genes (STING)–associated vasculopathy with onset in infancy (SAVI), and Aicardi‐Goutières syndrome (AGS) are rare and clinically complex immunodysregulatory diseases. With emerging knowledge of genetic causes and targeted treatments, a Task Force was charged with the development of “points to consider” to improve diagnosis, treatment, and long‐term monitoring of patients with these rare diseases.

Methods

Members of a Task Force consisting of rheumatologists, neurologists, an immunologist, geneticists, patient advocates, and an allied health care professional formulated research questions for a systematic literature review. Then, based on literature, Delphi questionnaires, and consensus methodology, “points to consider” to guide patient management were developed.

Results

The Task Force devised consensus and evidence‐based guidance of 4 overarching principles and 17 points to consider regarding the diagnosis, treatment, and long‐term monitoring of patients with the autoinflammatory interferonopathies, CANDLE/PRAAS, SAVI, and AGS.

Conclusion

These points to consider represent state‐of‐the‐art knowledge to guide diagnostic evaluation, treatment, and management of patients with CANDLE/PRAAS, SAVI, and AGS and aim to standardize and improve care, quality of life, and disease outcomes.