bluuebunny/crossref_metadata_2025 huggingface dataset:
A principle of least complexity for musical scales
Authors: Sevgen Alpar
Published: July 2002

The following properties of equally tempered scales are demonstrated in this Letter: For N semitones and M notes, each distinct scale (interval) structure can be represented by an associated multiplet of N scales. These scales allow themselves to be labeled by a set of integers {c}. Each label c is the difference between the number of sharps and flats in a given scale. The equivalence classes [c] modulo N form a commutative ring with unity. When the ratio N/M cannot be simplified further, then each member of a given multiplet will have a unique label (modulo N), different from the other members of the same multiplet. Because this labeling depends not on the interval structure of the multiplet but only on N and M, different multiplets with the same N and M values will have members carrying the same respective labels. Each equally tempered scale (interval) structure possesses a property which will be referred to as complexity. This Letter proposes a quantitative measure for complexity which distinguishes between different scale (interval) structures. For the particular case where N=12 and M=7, out of 462 possible different equally tempered scale structures, those with minimum complexity are the major scale and the modes, which suggests a minimum principle in music based on equally tempered scales. This simplicity of structure allows the practical use of key signatures in music.
From auditorium ray acoustics to wave acoustics: The next giant step
Authors: Medwin Herman
Published: July 2002

For at least five decades, architectural acousticians have used straight-line, infinite-frequency rays to determine which regions of an auditorium are insonified by a sound source and which are shadowed. In the next decade, leading acoustical designers of auditoriums will turn to predictions of the timing and amplitude of the different frequencies which partially reflect and bend around real auditorium components such as proscenium arches and boxes. The frequency dependence of wave reflection from rigid, finite surfaces has been developed by Clay et al. [J. Acoust. Soc. Am. 94, 2279 (1993)]. The calculation of the frequency dependence of the diffraction component, which some have called the BTM technique, is a digitally formulated, finite-wedge, frequency-spectral interpretation of the classic Biot–Tolstoy (1957) theory for impulse scatter from an infinite wedge. The BTM technique, which we described first at an ASA meeting in 1978, has been applied to shadowing by highway noise barriers [Medwin, J. Acoust. Soc. Am. 69, 1060–1064 (1981)] and to multifrequency reverberation from randomly rough, ocean surfaces [Keiffer and Novarini, in Computational Acoustics, edited by D. Lee et al. (1990), Vol. 1, pp. 67–81]. The procedure is explained in detail in Medwin and Clay [Fundamentals of Acoustical Oceanography (Academic, New York, 1998)]. The justification and analytical extension of this method have recently been formulated by Svensson [J. Acoust. Soc. Am. 106, 2331–2344 (1999)], who has made the program available on his web site and has suggested applications to auditoriums. The physical interpretation of the BTM technique will be described in terms of the spectral and temporal behavior of finite plates and wedges as modules of more complex components of auditorium surfaces.
Nonlinear sound scattering by subsurface bubble clouds in sea
Authors: Ostrovsky Lev A. , Kluzek Zinovy , Sutin Alexander M. , Soustova Irina A. , Matveev Alexander I. , Potapov Andrey I.
Published: July 2002

This presentation is based on a series of field experiments performed in a shallow sea (Baltic Sea). Investigated were bubble clouds of two types: one created in a motorboat’s jet, and the other existing naturally in the subsurface layer. A two-frequency signal (30 and 35 kHz) was radiated from below (at a 15-m depth) and received upon backscattering at sum and difference frequencies (65 and 5 kHz). The intensity of the scattered signal averaged over five subsequent pulses was measured. Theoretical consideration is given for reverberation at sum frequency and coherent propagation of the difference-frequency wave with subsequent reflection from the surface. The method is based on integration of fields nonlinearly scattered by single bubbles. A good qualitative and, in many cases, quantitative agreement was obtained between theory and experiment. A possibility to use nonlinear scattering for bubble distribution evaluation is also discussed.
High-frequency propagation through the wave boundary layer
Authors: Farmer David , Vagle Svein , Deane Grant
Published: July 2002

The surf zone presents one of the most extreme and challenging environments for the study of shallow water propagation where the complexities of a sloping beach, wave amplification, wave breaking, and the presence of dense bubble clouds combine to block or modify acoustic signals in a variety of ways. Propagation measurements at 12 and 100 kHz reveal sporadic drop-outs during which the signal can be abruptly blocked for 1–5 min or may be weakly detected but with strong modulation by the surface waves. Bubbles introduced to the water column through breaking are subject to persistent vertical mixing through the turbulent wave boundary layer which becomes progressively more energetic closer inshore. The bubble suspension is further modified by buoyancy and dissolution effects. Different acoustic frequencies are attenuated by bubbles of different radii, which in turn respond differently to the competing influences of turbulent mixing, buoyancy, and dissolution. We explore the implication of these effects on high-frequency propagation with a model that includes bubble injection, vertical mixing by the wave boundary layer, and bubble cloud evolution. The predictions are compared with observations of high-frequency propagation, wave amplification, wave breaking, and bubble distributions. [Work supported by the US ONR.]
Higher-order spectral analysis of shallow-water internal waves
Authors: Wang Tao , Gao Tian-Fu
Published: July 2002

Higher-order spectral analysis is a useful means for investigating nonlinear properties of shoaling random surface waves and a wide range of other phenomena, but has been considered to be fruitless for internal waves based on some studies in which the energies are represented by the deep-ocean GM model. However, it has been increasingly recognized that nonlinearity manifests itself in various shallow-water internal wave phenomena. The classical phase-blind power spectra contain information in the second-order statistics of a signal, and only suffice for describing Gaussian processes. Consequently, there are three main reasons for using higher-order spectra: to extract information due to deviations from Gaussianity, to recover correct phase properties, and thus to detect and quantify nonlinearity in time series. Existing techniques of bispectral analysis are particularly useful for studying quadratic interaction, the lowest order of nonlinear interactions. In this paper, it is found that internal waves on the continental shelf could produce a characteristic bispectral signal of sufficient strength to be verified by observations, and that real and imaginary parts of bispectra represent contributions to vertical and horizontal asymmetry of the internal wave elevations from each frequency pair, respectively. [Work supported by NSFC.]
Acoustics of mandolins
Authors: Cohen David , Rossing Thomas D.
Published: July 2002

We compare the normal modes of vibration and sound radiation from two Gibson F-type mandolins, one with an elliptical sound hole and one with f-holes. The instruments were constructed by the first author, using carved plates and other parts supplied by the Gibson company. Normal modes of vibration were determined with the help of electronic TV holography. Air cavity modes were determined by imbedding the instruments in sand to immobilize the plates. Normal modes in a mandolin are somewhat akin to those observed in guitars, although the coupling between plates and the enclosed air is weaker in mandolins.
Examination of surface roughness of porous soil via acoustic backscatter
Authors: Oelze Michael L. , Sabatier James
Published: July 2002

Work has been done to determine acoustically the pore properties of soils, such as porosity, permeability, and tortuosity. Early methods used probe microphones to determine the soil pore characteristics by looking at the attenuation and phase change of sound propagating through the soil pores. The attenuation and phase change of the sound were then related to a surface impedance that incorporated the soil pore properties. Seeking noninvasive means of finding these properties, forward scattering or acoustic level difference experiments were performed. It was seen that sound propagated over porous surfaces is reduced by the surface impedance and by the surface roughness. Theories have been developed to take into account the reduction in acoustic signal due to the finite surface impedance. Difficulties have arisen in separating the signal loss due to impedance and the signal loss from roughness scattering. Acoustic backscatter has been used to study the roughness statistics of soil surfaces in an effort to determine the effects of roughness apart from the surface impedance effects. The roughness statistics obtained via acoustic backscatter are then compared with alternate nonacoustic methods for examining surface roughness.
High-angle propagation modeling in the atmosphere
Authors: Di Xiao , Gilbert Kenneth E.
Published: July 2002

Many important situations in outdoor sound propagation involve high-angle propagation, for example, elevated sources and ground receivers, or vice versa. For such cases, we have compared two parabolic equation models: the GFPE model of Gilbert and Di and an atmospheric version of the RAM algorithm of Collins. Although the GFPE model, which is based on a split-step Fourier method, gives exact results for a homogeneous atmosphere (constant sound speed and constant density), it was initially thought to be less accurate for an inhomogeneous atmosphere than the RAM algorithm, which is based on high-order Padé approximations. Surprisingly, it was found that for cases with sufficiently weak atmospheric gradients, the GFPE is considerably more accurate at high angles than the atmospheric RAM model, given equal computational effort with both models. With increased computational effort (i.e., higher-order Padé expansions and shorter range steps), the RAM model gives high-angle accuracy comparable to the GFPE. As the atmospheric gradients steepen, the accuracy of the RAM model exceeds that of the GFPE. Nevertheless, for many typical atmospheric conditions, the GFPE offers sufficient accuracy and considerable computational savings. In this paper, we compare the GFPE and RAM models with benchmark calculations from a fast-field program (FFP) and discuss practical guidelines for using the GFPE and RAM models for high-angle propagation.
Detection and tracking of broadband airborne sources: An ‘‘acoustic fence’’ approach
Authors: Williams Jay E. , Williams Chad M. , Gilbert Kenneth E.
Published: July 2002

An ‘‘acoustic fence’’ concept is discussed as an advance detection system for approaching subsonic airborne vehicles. Each ‘‘post’’ of the acoustic fence is an array of three closely spaced microphones at right angles to each other on the ground. The posts themselves are spaced approximately 1 kilometer apart. It is shown that the azimuthal and elevation angles for an airborne vehicle can be accurately determined from simple cross correlation of the broadband time series measured at a single array (i.e., at one post). With two arrays, the vehicle track can be determined by finding the stationary points of an iterative nonlinear equation. The equation is of the form τp=f(τe), where τe and τp are, respectively, the estimated and predicted acoustic travel-time differences for two adjacent arrays. The stationary points, i.e., where τp=τe, allow the vehicle track to be computed directly from triangulation. Examples are discussed using both synthetic data and actual field measurements.
The estimation of excess attenuation of acoustic beam and its application
Authors: Pan Naixian
Published: July 2002

A theory of the excess attenuation for a conical beam is presented. The equation of attenuation coefficient shows the attenuation contributed by the item of Cv square is larger than that of Ct square about five times at least in the atmosphere. The theory shows that a significant difference of excess attenuation between emitting wave and back scattering on the same path. Excess attenuation and absorption both are taken into account in sodar data processing and the Ct square measured by sodar has a reasonable agreement in statistics with that measured by a filament thermometer. Based on the quantitative measurement of Ct square, sodar was used in an experiment whose aim was estimating the seeing quality of a candidate observatory in China in 1997. The seeing measured by sodar has a better correlation with the seeing measured by a differential image motion monitor in our experiment than that in other experiment in Russia (1988), in which the attenuation of sound had not been considered. The value of the excess attenuation is estimated to be the same order as the absorption in a typical clear day [E. H. Brown and S. F. Clifford, J. Acoust. Soc. Am. 60, 788–794 (1976)].
Standing waves in the brain and bone conduction hearing
Authors: Lenhardt Martin , Madsen Alan , Genova James , Neal Howard
Published: July 2002

Bone conduction hearing studies have a long history; however, in the last 25 years the topic of bone conduction hearing has been virtually abandonded. Delivering sound, including speech, to the head has certain advantages in high-noise communication. Difficulty arises in localization since bone conduction is a binaural perception, at least for tones under 10 kHz. At higher frequencies a robust lateralization of tones was observed for stimuli of 20 digital tones in the range of 4–18 kHz and 20–34 kHz. Inverting the listener’s body altered perception and transmission by bone conduction. Some tones in areas of resonance were altered in amplitude when the body was inverted, presumably due to increased cerebral spinal fluid pressure. Modeling of the skull as a sphere with rigid boundary conditions generally predicted direct observations. These findings also account for the observation of perception jumping from ear to ear with changes in frequency during ultrasonic bone conduction listening.
A one-dimensional wave model for a pneumatic tire
Authors: Pinnington R. J.
Published: July 2002

A wave equation for one-dimensional waves out of plane waves of an infinite tire belt are derived. The dynamics of the belt are regarded as those of a Timoshenko beam under tension, that is, uniformly supported by the sidewall stiffness. The sidewall is modeled here as a static stiffness controlled by the internal air pressure and the geometry of the tire cross section. The fourth-order differential wave equation is solved yielding two wave numbers as a function of frequency. These describe all the wave types of the belt. Below about 100 Hz the sidewall stiffness controls the deformation and there is only motion local to the excitation. At higher frequencies waves propagate around the belt with four different controlling mechanisms, tension, bending, shear, and longitudinal stiffness. The tire is made circular by the application of the boundary conditions, which is mainly a uniform force applied on a line across the width. The input and transfer mobilities of the belt are output, showing standing wave behavior below about 500 Hz, above which there are only propagating waves and near-field waves as on an infinite belt.
Kinematic factors underlying timing in connected speech
Authors: Tasko Stephen M. , Westbury John R.
Published: July 2002

Current understanding of the kinematic factors underlying speech timing has been largely derived from short, simple speech tasks such as citation words. However, timing analyses based upon acoustic segment durations have shown that timing rules differ for citation words and connected speech. Thus it is not clear how well temporal correlates of citation-style speech movement might generalize to connected speech. A better understanding of the articulatory bases of timing patterns associated with connected speech may aid in the refinement of natural-sounding articulatory-based speech synthesis. This study sought to determine temporal correlates of articulator fleshpoint movements in orally read speech recorded from 20 normal adult speakers of American English. Position histories associated with the tongue blade, tongue dorsum, jaw, and lower lip were segmented into series of movement strokes, and measures of distance, maximum speed, and duration were determined for each stroke. Canonical correlation analysis showed that for all articulators, these three measures were highly interrelated, and that 80% of the variance in movement duration could be accounted for by movement distance and maximum movement speed. These results suggest the possibility of predicting articulator timing based on a small number of kinematic measures. [Work supported by NIH Grant Nos. DC00820, DC03723, and DC03659.]
Effect of vocal fold tissue shear properties on phonation threshold pressure in a physical model of the larynx
Authors: Chan Roger , Titze Ingo
Published: July 2002

Previous analytical studies have shown that phonation threshold pressure (Pth), the minimum subglottal pressure required to initiate and sustain vocal fold oscillation, is directly related to the viscous shear properties (dynamic viscosity or viscous shear modulus) of the vocal fold mucosa in vibration [Titze, J. Acoust. Soc. Am. 83, 1536–1552 (1988); Chan, Ph.D. dissertation (1998)]. This relationship was verified empirically with a physical model of the larynx [Titze et al., J. Acoust. Soc. Am. 97, 3080–3084 (1995)], but no biological materials were tested in that study. This study attempted to establish the effects of biologically based tissue shear properties on Pth. Biomaterials with varying viscoelastic shear properties (abdominal subcutaneous fat, 0.01%–1.0% hyaluronic acid, and hyaluronic acid mixed with fibronectin) were incorporated into the artificial vocal fold mucosa of the physical model and self-sustained oscillation was induced. Results showed that no stable phonation could be established for fat, while higher Pth were consistently observed for higher concentrations of hyaluronic acid (with or without fibronectin), in correlation with their differences in viscous shear properties. These findings support the notion that hyaluronic acid could potentially be an optimal surgical bioimplant for the vocal fold mucosa, because it likely facilitates the ease of phonation. [Work supported by NIDCD.]
An integrated Printed Circuit Board (PCB) microphone
Authors: Hietanen Jarmo , Zacharov Nick
Published: July 2002

An electret microphone has been implemented into a printed circuit board. Due to novel construction the printed circuit board serves as the microphone backplate. Furthermore, other features of printed circuit board manufacturing technology are applied to minimize the number of components of the microphone. This results in a microphone that can be manufactured with the assembly of other electronic components during the manufacturing process. As a result a complete manufacturing process has been developed. To analyze the manufacturing process and the acoustical performance of the so-called PCB-microphone, the acoustics have been modeled, and backplate surface roughness, air gap thickness, electret charge, and overall sensitivity have been measured from prototypes.
Low-frequency response of the submerged human lung
Authors: Martin James S. , Rogers Peter H. , Cudahy Edward A. , Hanson Eric L.
Published: July 2002

A study was undertaken to determine the response of the human lung to low-frequency underwater sound in the range of 20 to 500 Hz. Experiments were conducted in a 1100 gal tank inside a hyperbaric chamber. Lung responses were measured by three independent techniques: a hydrophone close to the chest, an accelerometer attached to the chest, and a noninvasive ultrasound measurement of the lung surface. Ten subjects were tested. Each subject was tested twice at ambient pressures of 0, 10, 60, and 120 ft of sea water (FSW). The dominant feature of the response was a strong resonance that occurred, on average, at 39 Hz at surface pressure and 71 Hz at a depth of 120 FSW. This appears to be the fundamental resonance of the lungs. The depth dependence indicates that lung stiffness is dominated by gas in the lungs with a small contribution from the chest wall. Resonance Q’s were in the range of 5 to 7. There is evidence in the data of other low-frequency resonances that can be attributed to intestinal gas. Other than these, the lung acceleration response to incident pressure above resonance appears to be flat. [Work supported by ONR.]
Displacement in a continuously twisted structurally chiral medium due to axial loading
Authors: Lakhtakia Akhlesh , Sherwin Joseph A.
Published: July 2002

Loading of a linear, continuously twisted, structurally chiral medium (CTSCM) parallel to its helicoidal axis is analyzed, after assuming that the medium is locally triclinic. The roles of certain composite compliances are established, with a view to eventual use of CTSCMs for ultrasonic, infrared and optical applications.
Temporal dynamics of pitch strength in regular-interval noises: Effect of listening region and an auditory model
Authors: Wiegrebe L. , Hirsch H. S. , Patterson R. D. , Fastl H.
Published: July 2002

Recently, it was demonstrated that the pitch strength of a stimulus denoted “AABB” differed from rippled noise (RN) despite the fact that their long-term spectra and autocorrelation functions are identical (Wiegrebe et al., 1998). Rippled noise is generated by adding a delayed copy of Gaussian noise back to itself; AABB is generated by concatenating equal-duration, Gaussian-noise segments where every segment is repeated once. It was shown that a simple model based on a two-stage integration process separated by a nonlinear transformation explains the pitch-strength differences quantitatively. Here, we investigate how the spectral listening region influences pitch-strength differences between RN and AABB. Bandpass filtering the two stimuli with a constant bandwidth of 1 kHz revealed a systematic effect of center frequency. For relatively high pitches (corresponding to delays, d, of 4 or 5.6 ms, pitch strength differences between AABB and RN were absent when the pass band was between 0 and 1 kHz. When the pass band was between 3.5 and 4.5 kHz, pitch-strength differences were substantial. For lower pitches (d equal to or longer than 8 ms), AABB had a substantially greater pitch strength independent of the filter center frequency. The model presented in Wiegrebe et al. (1998) cannot capture these effects of center frequency. Here, it is demonstrated that it is possible to simulate the RN-AABB pitch-strength differences, and the effect of listening region, with a computer model of the auditory periphery. It is shown that, in an auditory model, pitch-strength differences are introduced by the nonlinear transformation possibly associated with half-wave rectification or mechanoelectrical transduction. In this experimental context, however, the nonlinearity has perceptual relevance only when the differences in short-term fluctuations of AABB and RN are preserved in auditory-filter outputs. The current experiments relate the purely functional model introduced in the preceding paper to basic properties of the peripheral auditory system. The implication for neural time constants of pitch processing is discussed.
A fast method for acoustic imaging of multiple three-dimensional objects
Authors: You Y. X. , Miao G. P. , Liu Y. Z.
Published: July 2002

This paper is concerned with the inverse problem for imaging multiple three-dimensional objects using the information of the far-field pattern of the scattered wave. A spatially dependent function, which has noticeably different values inside and outside the obstacle, is derived. A numerical method based on the characterization is developed to obtain a visualization of the obstacle. The most remarkable advantage of this method is that it does not need any prior knowledge about the geometry and physical properties of the scatterer, and requires only the information of the far-field measurements for a finite number of directions of incidence and observation distributed over a limited range. Furthermore, the scheme is very simple and fast since it avoids the use of the iterative procedure and requires only the solution of a linear system. Some numerical examples with synthetic far-field data are given showing the practicality and efficiency of this scheme.
A comparative study of transforms for use in digital audio data compression
Authors: Rulon B. E. , Shaw M. F. , Donohue K. D.
Published: July 2002

This paper provides a subjective quality analysis of transforms used in audio compression algorithms for a class of music signals. A 34-subject listener test compares three transforms in conjunction with an MPEG I layer 1 compression scheme. One test compares the performances of the discrete wavelet packet transform (DWPT) and the modified discrete cosine transform (MDCT) used in MPEG. Another test compares the performances of a DWPT eight-level nonuniform critical-band split and a DWPT five-level uniform subband split. Results indicate that the critical-band split provides significantly better quality than the uniform subband split for sounds with tonal and strong low-frequency content, while the DWPT outperforms the MDCT with significant improvement for nontonal sounds.
Steady-state behavior of dilute polymers in elongational flow. Dependence of the critical elongational rate on chain length, hydrodynamic interaction, and excluded volume
Authors: Hernández Cifre J. G. , Garcı́a de la Torre J.
Published: July 2002

The steady-state properties of flexible polymer chains in solutions undergoing elongational flow have been studied using Brownian dynamics simulation. The coil–stretch transition is observed when the elongational rate, ε̇ exceeds a certain critical value ε̇c. In this work, we describe in detail the simulation procedure and how to extract polymer dimensions, solution viscosity, and birefringence from the trajectories. Preliminary simulations involving no hydrodynamic interaction (HI) are used to check the simulation procedures by comparing their results with theoretical predictions for such an (unphysical) case. Afterwards, simulations with fluctuating nonaveraged HI are carried out to provide results comparable with experiments. After simulations with and without intramolecular potential, we arrive at a most important conclusion: the chain length dependence of ε̇c is the same in theta conditions as in good solvent conditions. Combining ε̇c with other solution properties such as the longest relaxation time, the intrinsic viscosity, and the radius of gyration, dimensionless compound quantities can be formulated. From our simulation results, we obtain numerical values for such quantities, which include the HI effect, and which are therefore useful for analyzing experimental data.
A new transient network model for associative polymer networks
Authors: Wientjes R. H. W. , Jongschaap R. J. J. , Duits M. H. G. , Mellema J.
Published: July 2002

A new model for the linear viscoelastic behavior of polymer networks is developed. In this model the polymer system is described as a network of spring segments connected via sticky points (as in the Lodge model). [Lodge, A. S., “A network theory of flow birefringence and stress in concentrated polymer solutions,” Trans. Faraday Soc. 52, 120–130 (1956).] An important extension (with respect to previous models) is that chain connectivity is taken into account. All segments that are located in between connected stickers are supposed to carry stress. The attachment and detachment of stickers is described with kinetic equations in which activation energies play a role. Simultaneous transitions involving groups of stickers are allowed. The model shows a strong dependence upon the number of segments per chain. Broad relaxation spectra can be obtained. The storage modulus can have more than one plateau corresponding with the fact that stress relaxation may need the breakup of several bonds.
Risk of Prostate Cancer in US Veterans With Rheumatoid Arthritis
Authors: Wheeler Austin M. , Roul Punyasha , Yang Yangyuna , Brittan Kaitlyn M. , Sayles Harlan , Singh Namrata , Sauer Brian C. , Cannon Grant W. , Baker Joshua F. , Mikuls Ted R. , England Bryant R.
Published: April 2022

Objective

Patients with rheumatoid arthritis (RA) have an increased risk of select cancers, including lymphoma and lung cancer. Whether RA influences prostate cancer risk is uncertain. We aimed to determine the risk of prostate cancer in patients with RA compared to patients without RA in the Veterans Health Administration (VA).

Methods

We performed a matched (up to 1:5) cohort study of male patients with and without RA in the VA from 2000 to 2018. RA status, as well as covariates, were obtained from national VA databases. Prostate cancer was identified through linked VA cancer databases and the National Death Index. Multivariable Cox models compared prostate cancer risk between patients with RA and patients without RA, including models that accounted for retention in the VA system.

Results

We included 56,514 veterans with RA and 227,284 veterans without RA. During 2,337,104 patient‐years of follow‐up, 6,550 prostate cancers occurred. Prostate cancer incidence (per 1,000 patient‐years) was 3.50 (95% confidence interval [95% CI] 3.32–3.69) in patients with RA and 2.66 (95% CI 2.58–2.73) in patients without RA. After accounting for confounders and censoring for attrition of VA health care, RA was modestly associated with a higher prostate cancer risk (adjusted HR [HRadj] 1.12 [95% CI 1.04–1.20]). There was no association between RA and prostate cancer mortality (HRadj 0.92 [95% CI 0.73–1.16]).

Conclusion

RA was associated with a modestly increased risk of prostate cancer, but not prostate cancer mortality, after accounting for relevant confounders and several potential sources of bias. However, even minimal unmeasured confounding could explain these findings.
Ion Irradiation Effect on Mechanical Properties and Corrosion Resistance of a Cu50Zr50 Metallic Glass
Authors: Zhang Zida , Che Pengcheng , Zhang Jian , Fan Hongbo , Ning Zhiliang , Sun Jianfei , Huang Yongjiang
Published: April 2022

The effect of H+‐ion irradiation on the structure and properties of a Cu50Zr50 metallic glass (MG) is investigated. High‐energy synchrotron X‐Ray diffraction results indicate that the glass maintains its amorphous nature after ion irradiation. As the ion fluence increases, the atomic bond length of MGs becomes shorter, whereas the nanohardness and Young's modulus increase from 7.08 ± 0.01 and 111.3 ± 1.1 GPa for the as‐spun sample to 8.59 ± 0.06 and 123.1 ± 1.3 GPa for the sample irradiated with 2 × 1016 cm−2 fluence. The corrosion potential of the studied MG in 1 mol L−1 HCl increases from −0.5953 to −0.4519 V, suggesting an enhanced corrosion resistance of MGs after ion irradiation. The modification of mechanical properties and corrosion resistance can be interpreted from the ion irradiation‐induced structural evolution. The results obtained herein can be beneficial for better understanding the mechanical properties and corrosive behaviors of MGs under extreme conditions like ion irradiation, thus promoting their industrial applications.
A Continuous Extrusion‐Shear (ES) Composite Process for Significantly Improving the Metallurgical Bonding and Textures Regulations and Grain Refinements of Al/Mg Bimetallic Composite Rods
Authors: Tian Ye , Hu Hong-Jun , Li Yang , Zhao Jian-Xing , Hong Xing , Jiang Bin , Zhang Ding-Fei
Published: April 2022

To improve metallurgical bonding and texture regulations and grain refinements of Al/Mg bimetallic composite rods, Al/Mg bimetallic composite rods have been prepared by direct extrusion (DE) and extrusion‐shear (ES) processes. The bonding layers of the composite rods prepared by DE and ES processes with different preheating temperatures are investigated. Research results demonstrated that good metallurgical bonding layers with no voids and cracks are formed by the ES process with 390 °C, there are relatively poor bonding layers during the DE process and ES process with 330 and 360 °C. The microstructures and textures and dynamic recrystallization (DRX) evolution of Al/Mg bimetallic composite rods fabricated by the ES process are analyzed. Simultaneously, the microhardness and the shearing strength of bonding layers in the Al/Mg composite rods are investigated. The research results show that the grains are refined significantly due to DRX during the ES process. The texture intensities of basal planes <0001> and non‐basal textures <11‐20>,<10‐10> weakens as the preheating temperatures increased during the ES process. The DRX volume fraction is enhanced. The texture strength of the Al alloy weakens during the ES process, and the texture characteristics of the Al alloy changes obviously after the ES process. The ES process can improve metallurgical bonds in Al/Mg composite rods by applying shear forces and has great potential in improving the comprehensive properties of bimetallic materials.
High‐Speed Antagonistic Shape Memory Actuator for High Ambient Temperatures
Authors: Britz Rouven , Rizzello Gianluca , Motzki Paul
Published: April 2022

This work presents the development of an innovative shape memory alloy (SMA) actuator principle, which allows high‐speed switching cycles through the decoupling of antagonistically arranged SMA wires. Being optimized for the use at high ambient temperatures up to 65 °C, a possible application area is the active venting of injection molds where it can be used to expel air, which is trapped during the injection mold process. The patented actuator principle is based on a decoupled agonist–antagonist SMA‐spring system and allows a high‐speed closing movement by a compact and lightweight design. Another innovation compared to conventional antagonistic SMA actuator systems is the integrated fail‐safe mechanism, which guarantees a defined closed state in case of power failure. Subsequently, in the motivation the need for active venting valves for injection molding is first described. Second, the novel actuator principle is introduced, and the development of an electronics concept is discussed. Finally, the design process, assembly, and validation of two iterations of the actuator prototype are presented. The final prototype validation measurements showcase high performance by valve strokes of 1 mm within 100 ms at ambient temperature of 65 °C.
Magnetically Switchable Adhesion and Friction of Soft Magnetoactive Elastomers
Authors: Kovalev Alexander , Belyaeva Inna A. , von Hofen Christian , Gorb Stanislav , Shamonin Mikhail
Published: April 2022

Herein, the effect of an applied moderate (≈240 mT) magnetic field on the work of adhesion (WoA) of mechanically soft (the shear modulus ≈10 kPa) magnetoactive elastomer (MAE) samples with two different mass fractions (70 and 80 wt%) of carbonyl iron powder (CIP) is concerned. The unfilled elastomer sample is used for comparison. Due to some sedimentation of filling particles, the concentration of inclusions in thin (≈10 μm) subsurface layers is different. It is shown that the WoA increases (up to 1.8‐fold) on the particle‐enriched side (PES) in the magnetic field and its value is higher for higher filler concentration. On the particle‐depleted side (PDS), WoA does not depend on particle concentration and on the magnetic field. Adhesion and friction are coupled in MAEs. No statistically significant difference in the friction coefficient, determined from the extended Amontons´ law, depending on sample side, CIP concentration, or presence of magnetic field is found. However, the PDS in the magnetic field demonstrates significantly higher critical shear stress compared to that for the PES or PDS in the absence of magnetic field. Correlations between different surface properties are discussed. Obtained results are useful for the development of magnetically controllable soft robots.
A Ceramic‐Electrolyte Glucose Fuel Cell for Implantable Electronics
Authors: Simons Philipp , Schenk Steven A. , Gysel Marco A. , Olbrich Lorenz F. , Rupp Jennifer L. M.
Published: April 2022

Next‐generation implantable devices such as sensors, drug‐delivery systems, and electroceuticals require efficient, reliable, and highly miniaturized power sources. Existing power sources such as the Li–I2 pacemaker battery exhibit limited scale‐down potential without sacrificing capacity, and therefore, alternatives are needed to power miniaturized implants. This work shows that ceramic electrolytes can be used in potentially implantable glucose fuel cells with unprecedented miniaturization. Specifically, a ceramic glucose fuel cell—based on the proton‐conducting electrolyte ceria—that is composed of a freestanding membrane of thickness below 400 nm and fully integrated into silicon for easy integration into bioelectronics is demonstrated. In contrast to polymeric membranes, all materials used are highly temperature stable, making thermal sterilization for implantation trivial. A peak power density of 43 µW cm−2, and an unusually high statistical verification of successful fabrication and electrochemical function across 150 devices for open‐circuit voltage and 12 devices for power density, enabled by a specifically designed testing apparatus and protocol, is demonstrated. The findings demonstrate that ceramic‐based micro‐glucose‐fuel‐cells constitute the smallest potentially implantable power sources to date and are viable options to power the next generation of highly miniaturized implantable medical devices.
Pre‐Buried Additive for Cross‐Layer Modification in Flexible Perovskite Solar Cells with Efficiency Exceeding 22%
Authors: Zheng Zhonghao , Li Faming , Gong Jue , Ma Yinyi , Gu Jinwen , Liu Xiaochun , Chen Shuhan , Liu Mingzhen
Published: April 2022

Halide perovskites have shown superior potentials in flexible photovoltaics due to their soft and high power‐to‐weight nature. However, interfacial residual stress and lattice mismatch due to the large deformation of flexible substrates have greatly limited the performance of flexible perovskite solar cells (F‐PSCs). Here, ammonium formate (HCOONH4) is used as a pre‐buried additive in electron transport layer (ETL) to realize a bottom‐up infiltration process for an in situ, integral modification of ETL, perovskite layer, and their interface. The HCOONH4 treatment leads to an enhanced electron extraction in ETL, relaxed residual strain and micro‐strain in perovskite film, along with reduced defect densities within these layers. As a result, a top power conversion efficiency of 22.37% and a certified 21.9% on F‐PSCs are achieved, representing the highest performance reported so far. This work links the critical connection between multilayer mechanics/defect profiles of ETL‐perovskite structure and device performance, thus providing meaningful scientific direction to further narrowing the efficiency gap between F‐PSCs and rigid‐substrate counterparts.
Electronic Structure Engineering of Single‐Atom Ru Sites via Co–N4 Sites for Bifunctional pH‐Universal Water Splitting
Authors: Rong Chengli , Shen Xiangjian , Wang Yuan , Thomsen Lars , Zhao Tingwen , Li Yibing , Lu Xunyu , Amal Rose , Zhao Chuan
Published: April 2022

The development of bifunctional water‐splitting electrocatalysts that are efficient and stable over a wide range of pH is of great significance but challenging. Here, an atomically dispersed Ru/Co dual‐sites catalyst is reported anchored on N‐doped carbon (Ru/Co–N–C) for outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both acidic and alkaline electrolytes. The Ru/Co–N–C catalyst requires the overpotential of only 13 and 23 mV for HER, 232 and 247 mV for OER to deliver a current density of 10 mA cmgeo−2 in 0.5 m H2SO4 and 1 m KOH, respectively, outperforming benchmark catalysts Pt/C and RuO2. Theoretical calculations reveal that the introduction of Co–N4 sites into Ru/Co–N–C efficiently modify the electronic structure of Ru by enlarging Ru–O covalency and increasing Ru electron density, which in turn optimize the bonding strength between oxygen/hydrogen intermediate species with Ru sites, thereby enhancing OER and HER performance. Furthermore, the incorporation of Co–N4 sites induces electron redistribution around Ru–N4, thus enhancing corrosion–resistance of Ru/Co–N–C during acid and alkaline electrolysis. The Ru/Co–N–C has been applied in a proton exchange membrane water electrolyzer and steady operation is demonstrated at a high current density of 450 mA cmgeo−2 for 330 h.
Liquid Crystal Elastomer with Integrated Soft Thermoelectrics for Shape Memory Actuation and Energy Harvesting
Authors: Zadan Mason , Patel Dinesh K. , Sabelhaus Andrew P. , Liao Jiahe , Wertz Anthony , Yao Lining , Majidi Carmel
Published: April 2022

Liquid crystal elastomers (LCEs) have attracted tremendous interest as actuators for soft robotics due to their mechanical and shape memory properties. However, LCE actuators typically respond to thermal stimulation through active Joule heating and passive cooling, which make them difficult to control. In this work, LCEs are combined with soft, stretchable thermoelectrics to create transducers capable of electrically controlled actuation, active cooling, and thermal‐to‐electrical energy conversion. The thermoelectric layers are composed of semiconductors embedded within a 3D printed elastomer matrix and wired together with eutectic gallium–indium (EGaIn) liquid metal interconnects. This layer is covered on both sides with LCE, which alternately heats and cools to achieve cyclical bending actuation in response to voltage‐controlled Peltier activation. Moreover, the thermoelectric layer can harvest energy from thermal gradients between the two LCE layers through the Seebeck effect, allowing for regenerative energy harvesting. As demonstrations, first, closed‐loop control of the transducer is performed to rapidly track a changing actuator position. Second, a soft robotic walker that is capable of walking toward a heat source and harvesting energy is introduced. Lastly, phototropic‐inspired autonomous deflection of the limbs toward a heat source is shown, demonstrating an additional method to increase energy recuperation efficiency for soft systems.
Classical Complement Pathway Inhibition in a “Human‐On‐A‐Chip” Model of Autoimmune Demyelinating Neuropathies
Authors: Rumsey John W. , Lorance Case , Jackson Max , Sasserath Trevor , McAleer Christopher W. , Long Christopher J. , Goswami Arindom , Russo Melissa A. , Raja Shruti M. , Gable Karissa L. , Emmett Doug , Hobson‐Webb Lisa D. , Chopra Manisha , Howard James F. , Guptill Jeffrey T. , Storek Michael J. , Alonso‐Alonso Miguel , Atassi Nazem , Panicker Sandip , Parry Graham , Hammond Timothy , Hickman James J.
Published: April 2022

Chronic autoimmune demyelinating neuropathies are a group of rare neuromuscular disorders with complex, poorly characterized etiology. Here the authors describe a phenotypic, human‐on‐a‐chip (HoaC) electrical conduction model of two rare autoimmune demyelinating neuropathies, chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN), and explore the efficacy of TNT005, a monoclonal antibody inhibitor of the classical complement pathway. Patient sera is shown to contain anti‐GM1 IgM and IgG antibodies capable of binding to human primary Schwann cells and induced pluripotent stem cell‐derived motoneurons (MNs). Patient autoantibody binding is sufficient to activate the classical complement pathway, resulting in detection of C3b and C5b‐9. A HoaC model, using a microelectrode array with directed axonal outgrowth over the electrodes treated with patient sera, exhibits reductions in MN action potential frequency and conduction velocity. TNT005 rescued the serum‐induced complement deposition and functional deficits while treatment with an isotype control antibody has no rescue effect. These data indicate that complement activation by CIDP and MMN patient serum is sufficient to mimic neurophysiological features of each disease and that complement inhibition with TNT005 is sufficient to rescue these pathological effects and provide efficacy data included in an investigational new drug application, demonstrating the model's translational potential.
Nonhuman primate abnormal behavior: Etiology, assessment, and treatment
Authors: Lutz Corrine K. , Coleman Kristine , Hopper Lydia M. , Novak Melinda A. , Perlman Jaine E. , Pomerantz Ori
Published: April 2022

Across captive settings, nonhuman primates may develop an array of abnormal behaviors including stereotypic and self‐injurious behavior. Abnormal behavior can indicate a state of poor welfare, since it is often associated with a suboptimal environment. However, this may not always be the case as some behaviors can develop independently of any psychological distress, be triggered in environments known to promote welfare, and be part of an animal's coping mechanism. Furthermore, not all animals develop abnormal behavior, which has led researchers to assess risk factors that differentiate individuals in the display of these behaviors. Intrinsic risk factors that have been identified include the animal's species and genetics, age, sex, temperament, and clinical condition, while environmental risk factors include variables such as the animal's rearing, housing condition, husbandry procedures, and research experiences. To identify specific triggers and at‐risk animals, the expression of abnormal behavior in captive nonhuman primates should be routinely addressed in a consistent manner by appropriately trained staff. Which behaviors to assess, what assessment methods to use, which primates to monitor, and the aims of data collection should all be identified before proceeding to an intervention and/or treatment. This article provides guidance for this process, by presenting an overview of known triggers and risk factors that should be considered, steps to design a comprehensive evaluation plan, and strategies that might be used for prevention or treatment. It also outlines the tools and processes for assessing and evaluating behavior in an appendix. This process will lead to a better understanding of abnormal behavior in captive primate colonies and ultimately to improved welfare.
Konzentriertes Wässriges Peroxodikarbonat: Effiziente Elektrosynthese und Anwendungen in Epoxidierungen, S‐, und N‐Oxidationen
Authors: Seitz Ann‐Katrin , Kohlpaintner Philipp J. , van Lingen Tim , Dyga Marco , Sprang Fiona , Zirbes Michael , Waldvogel Siegfried R. , Gooßen Lukas J.
Published: April 2022

Peroxodikarbonate sind potenziell leistungsstarke, nachhaltige Oxidationsmittel und deshalb von großem Interesse. Diese konnten aber bisher nur in unzureichend hohen Konzentrationen und mit unbefriedigender Energieeffizienz erhalten werden. Konzentrierte (>0.9 mol L−1) Peroxodikarbonat‐Lösungen konnten nun erstmals durch Elektrolyse von wässrigen K2CO3/Na2CO3/KHCO3‐Lösungen bei hohen Stromdichten von 3.33 A cm−2 in einem effizient gekühlten Flusselektrolyseur mittels einer Bor‐dotierten Diamant (BDD)‐Anode und Edelstahlkathode erzeugt werden. Die potenzielle Anwendung als Oxidationsmittel konnte klar anhand verschiedener Reaktionen wie Sulfoxidation, N‐Oxidation und Epoxidierung gezeigt werden.