bluuebunny/crossref_metadata_2025 huggingface dataset:
A spectral approach to 3-D object scattering in layered media applied to scattering from submerged spheres
Authors: Makris Nicholas C.
Published: July 2002

A spectral formulation for 3-D object scattering in a layered medium is described. The formulation is valid when the source and receiver are sufficiently far from the object that multiple scattering between the object and waveguide boundaries can be neglected and the scattered field can be expressed as a linear function of the object’s plane wave scattering function. An analytic expression is then derived for the field scattered from a spherical object in a stratified medium. Since the expression is in terms of 1-D wave number integrals, it is computationally efficient to implement, allows detailed investigation of the scattered field in the vicinity of the object, and enables scattering of evanescent waves to be incorporated by analytic continuation. Computations for a noncompact sphere (1<ka) illustrate the essential characteristics of 3-D object scattering in a shallow but multi-modal waveguide. Relative to free-space scattering, a significant decrease in the level of the scattered field in the forward direction as well as a pronounced directional beaming effect in the vicinity of the sphere are discovered. Another primary finding is that multistatic observations of the scattered field, distributed over an azimuthal aperture greatly in excess of π/(ka), will typically be necessary to classify an object submerged in a shallow-water waveguide at ranges exceeding the water column depth.
Sound propagation in air-saturated random packings of beads
Authors: Allard Jean F. , Henry Michel , Tizianel Julian , Kelders Luc , Lauriks Walter
Published: July 2002

In the pore space of packed grain material, transport properties are characterized by macroscopic parameters. Some of them, tortuosity, characteristic dimensions, viscous permeability, and trapping constant, are measured for a random packing of glass beads and compared to evaluations performed in previous studies. These parameters are used to predict the surface impedance at normal incidence of a layer of glass beads. The predictions are compared to measurements performed at normal incidence in a Kundt tube.
Acoustic behavior of chimney pipes
Authors: Kokkelmans Servaas J. J. M. F. , Verge Marc-Pierre , Hirschberg A. , Wijnands A. P. J. , Schoffelen R. L. M.
Published: July 2002

The objective of this work is to study the acoustic behavior of chimney organ pipes. The working hypothesis is that its role is to reinforce the fifth harmonic of the tone of a stopped pipe. According to Helmholtz, the chimney should have the length of an open pipe resonating at the frequency of the fifth harmonic. This design appears to be the least favorable one, except if the chimney is placed half inside and half outside the main pipe, and should therefore be avoided. The ratio of the modulus of the admittance of the different harmonics appears to describe, for the chimney pipe used in this study, the dependency of the ratio of the measured amplitude of the fifth, third, and first harmonic with the geometry of the chimney. The admittance curve can therefore be used to determine the effects of the geometry of the chimney on the timbre of the organ pipe. This result is used in order to determine the optimal diameter of the chimney as a function of its length.
Active impedance control within a cylindrical waveguide for generation of low-frequency, underwater plane traveling waves
Authors: Finneran James J. , Hastings Mardi C.
Published: July 2002

A cylindrical, water-filled acoustic waveguide with an active termination was used to generate constant-frequency, plane traveling waves. The waveguide was constructed of acrylic tubing with an underwater sound projector flanged to each end. One projector acted as the primary source and generated continuous harmonic waves. The active control system measured the transfer function between two hydrophones located inside the waveguide and used a pattern search algorithm to adjust the secondary source amplitude and phase in order to drive the measured transfer function to that for a plane traveling wave. The active control system was able to reduce the reflection coefficient to below 0.05 within the frequency range 12.5–400 Hz and adjust the acoustic pressure/particle velocity ratio to match that of a plane progressive wave.
Thermoacoustic natural gas liquefier
Authors: Swift Gregory W. , Wollan John J.
Published: July 2002

An experimental thermoacoustic natural-gas liquefier has been built and tested. It comprises a standing-wave thermoacoustic engine and a traveling-wave refrigerator (a pulse-tube refrigerator). The engine and refrigerator share a common resonator, filled with 3 MPa helium gas and operating at 40 Hz. The engine is heated by external combustion of natural gas, while the refrigerator cools and liquefies a methane stream, so the complete system functions as a natural-gas-fired natural-gas liquefier having no moving parts. Both the engine and refrigerator have operated above 20% of their respective Carnot efficiencies. Compared to other thermoacoustics research hardware, this experimental system is very powerful, with up to 20 kW of acoustic power delivered from the engine to the resonator and up to 2 kW of refrigeration power at 130 K provided by the refrigerator. Nevertheless, much larger systems will be required for commercial success. [Work supported by the Office of Fossil Energy in the U.S. DOE and by Cryenco, Inc.]
Shot-to-shot variability of acoustic axis of a spark-source lithotripter
Authors: Sapozhnikov Oleg A. , Bailey Michael R. , Crum Lawrence A.
Published: July 2002

The shot-to-shot spatial variability of acoustic and cavitation fields of a spark-source lithotripter was investigated. Spark jitter, variation in the arc strength and location is cited for lack of repeatability in laboratory experiments and is thought to contribute to the success of the Dornier HM3 in comminuting kidney stones, which tend to move during treatment. Transverse variability of the acoustic focus was assessed by measuring the location of the shock wave (SW) induced fountain. The water bath was lowered and a small cup half-filled with ink and having a gridded paper roof was placed at the level of the focus. An ink drop created by the fountain was recorded on the paper. Drop diameter varied from 0–12 mm, location of its center varied by about 1 mm. The extent and location of the cavitation field was measured by high-speed camera. The cavitation cluster was 1×10 cm at its largest extent but bubbles collapsed in a narrow 1–2 mm line. The location of the line was repeatable to within 2 mm. The results indicated that spark jitter affected SW amplitude but had little effect on the location of the acoustic axis. [Work supported by NIH (DK 43881), CRDF and RFBR.]
Pitch accent in spoken-word recognition in Japanese
Authors: Cutler Anne , Otake Takashi
Published: July 2002

Three experiments addressed the question of whether pitch-accent information may be exploited in the process of recognizing spoken words in Tokyo Japanese. In a two-choice classification task, listeners judged from which of two words, differing in accentual structure, isolated syllables had been extracted (e.g., ka from baka HL or gaka LH); most judgments were correct, and listeners’ decisions were correlated with the fundamental frequency characteristics of the syllables. In a gating experiment, listeners heard initial fragments of words and guessed what the words were; their guesses overwhelmingly had the same initial accent structure as the gated word even when only the beginning CV of the stimulus (e.g., na- from nagasa HLL or nagashi LHH) was presented. In addition, listeners were more confident in guesses with the same initial accent structure as the stimulus than in guesses with different accent. In a lexical decision experiment, responses to spoken words (e.g., ame HL) were speeded by previous presentation of the same word (e.g., ame HL) but not by previous presentation of a word differing only in accent (e.g., ame LH). Together these findings provide strong evidence that accentual information constrains the activation and selection of candidates for spoken-word recognition.
Enhancing the speech envelope of continuous interleaved sampling processors for cochlear implants
Authors: Geurts Luc , Wouters Jan
Published: July 2002

A new method to code the speech envelope in continuous interleaved sampling (CIS) processors for cochlear implants is proposed. In this enhanced envelope, the rapid adaptation seen in the response of auditory nerves to sound stimuli is incorporated. Two strategies, one using the standard envelope (CIS) and one using the enhanced envelope (EECIS), were tested perceptually with six postlingually deafened users of the LAURA cochlear implant. The tests included identification of stop consonants in three different vowel contexts and monosyllabic consonant–vowel–consonant (CVC) words. Significant improvements in correct identification scores were observed for stop consonants in intervocalic /a/ context (p=0.026): average results varied from 46% correct for CIS to 55% for EECIS. This improvement was mainly due to the better transmission of place of articulation. The differences in identification scores for stop consonants in /i/ and /u/ context were not significant. The identification scores for the medial vowels of the CVC words were significantly higher when the EECIS strategy was used: average results increased from 39% correct to 46% correct (p=0.018). No significant differences were observed between the results for initial and final consonants of the CVC words. The present results demonstrate that the inclusion of the rapid adaptation in the speech processing for cochlear implants can improve speech intelligibility.
Sensitivity of human subjects to head-related transfer-function phase spectra
Authors: Kulkarni Abhijit , Isabelle S. K. , Colburn H. S.
Published: July 2002

Head-related transfer functions (HRTFs) for human subjects in anechoic space were modeled with modified phase spectra, including minimum-phase-plus-delay, linear-phase, and reversed-phase-plus-delay functions. The overall (wide-band) interaural time delay (ITD) for the modeled HRTFs was made consistent with that of the empirical HRTFs by setting the position-dependent, frequency-independent delay in the HRTF for the lagging ear. Signal analysis of the minimum-phase-plus-delay reconstructions indicated that model HRTFs deviate from empirical HRTF measurements maximally for contralateral azimuths and low elevations. Subjects assessed the perceptual validity of the model HRTFs in a four-interval, two-alternative, forced-choice discrimination paradigm. Results indicate that monaural discrimination performance of subjects was at chance for all three types of HRTF models. Binaural discrimination performance was at chance for the linear-phase HRTFs, was above chance for some locations for the minimum-phase-plus-delay HRTFs, and was above chance for all tested locations for the reversed-phase-plus-delay HRTFs. An analysis of low-frequency timing information showed that all of these results are consistent with efficient use of interaural time differences in the low-frequency components of the stimulus waveforms. It is concluded that listeners are insensitive to HRTF phase spectra as long as the overall ITD of the low-frequency components does not provide a reliable cue. In particular, the minimum-phase-plus-delay approximation to the HRTF phase spectrum is an adequate approximation as long as the low-frequency ITD is appropriate. These results and conclusions are all limited to the anechoic case when the HRTFs correspond to brief impulse responses limited to a few milliseconds.
Observations of contrast agents during insonation with a high-speed imaging system
Authors: Dayton Paul , Chomas James , Ferrara Katherine
Published: July 2002

With the use of a high-speed imaging system, fluctuations in microbubble radius and asymmetries leading to destruction at clinical ultrasonic frequencies can be evaluated. The extraordinary temporal resolution necessary to obtain these observations was achieved using a 10-W copper-vapor laser in conjunction with a high-speed digital camera. This combination produces an effective shutter speed of 50 MHz, which allows for imaging of the fluctuations in radius over the acoustic pressure cycle. Using this imaging technique in combination with image-analysis software, radius versus time curves of bubble expansion and contraction during the acoustic pressure cycle can be produced. It is observed that contrast agent microbubbles can expand and contract by a large fraction of their resting diameter (130%) during insonation while remaining intact at low acoustic pressures (180 kPa). At higher acoustic pressures (2.3 MPa), bubbles can expand up to 500% during the rarefactional half-cycle, after which they usually fragment into smaller bubbles. Since the echo from a bubble is determined by the radial fluctuation and resulting wall velocity, mapping such changes over time is essential if the radiated pressure waveform is to be predicted. For Biomedical Ultrasound/Bioresponse to Vibration Best Student Paper Award.
Intelligibility of 1/3-octave speech: Greater contribution of frequencies outside than inside the nominal passband
Authors: Warren Richard M. , Bashford James A.
Published: July 2002

We reported previously that “everyday” sentences were highly intelligible when limited to a 1/3-octave passband centered at 1,500 Hz and having transition-band slopes of approximately 100 dB/octave. The present study determined the relative contributions to intelligibility made by the passband (PB) and the transition bands (TBs) by partitioning the same bandpass sentences using 2,000-order FIR filtering. Intelligibility scores were: PB with both TBs, 92%; deletion of both TBs (leaving only the 1/3-octave PB with nearly vertical slopes), 24%; deletion of the PB (leaving both TBs separated by a 1/3-octave gap), 83%. These and other results indicate a remarkable ability to compensate for severe spectral tilt and the consequent importance of considering frequencies outside the nominal passband in interpreting studies using filtered speech.
The effect of reverberation on a new binaural noise cancellation algorithm for hearing aids
Authors: Goueygou Marc , Lockwood Michael E. , Elledge Mark E. , Bilger Robert C. , Jones Douglas L. , Lansing Charissa R. , Liu Chen , O’Brien William D. , Wheeler Bruce C.
Published: July 2002

A new algorithm was developed to emulate the ‘‘cocktail party effect’’ in hearing aids [Liu et al., ASA Symposium (1997)]. Speech signals are received binaurally; the interferers and the desired source are localized; and the signal from the strongest interferer is cancelled by frequency and time selective beamforming. Here we evaluate the algorithm’s performance in real conditions including reverberation. Binaural recordings of speech uttered simultaneously by three different speakers around the receivers were made in three different rooms (an anechoic room, a mildly and a highly reverberant room). Noise cancellation was evaluated by the intelligibility weighted SNR (IWSNR) gain between processed and unprocessed signals [Link and Buckley, J. Acoust. Soc. Am. 91]. Algorithm performance is severely degraded as the reverberation time increases: the IWSNR gain falls from 8–9 dB in the anechoic room to 1–2 dB in the highly reverberant room. Also, knowing of the exact location of the sources does not add significant improvement. The results suggest that the room impulse response be deconvolved from the received signals to suppress the multiple reflections of sound. We suggest a new strategy combining noise cancellation with blind identification of the room impulse response. [Research supported by the Beckman Institute.]
High-resolution finite-volume methods for acoustic waves in periodic and random media
Authors: Fogarty Tiernan R. , LeVeque Randall J.
Published: July 2002

High-resolution numerical methods originally developed for shock capturing in the context of nonlinear conservation laws are found to be very useful for solving acoustics problems in rapidly varying heterogeneous media. These methods are based on solving Riemann problems at the interface between grid cells, which resolve waves into transmitted and reflected components at each interface. The wave-propagation method developed in R. J. LeVeque [J. Comput. Phys. 131, 327–353 (1997)] and implemented in the CLAWPACK software package is tested on several acoustics problems with periodic or random media in one and two space dimensions. A new limiter function is presented for solving problems in a periodic medium where numerical instabilities are observed with standard limiters.
A broadband passive–active sound absorption system
Authors: Smith Jerome P. , Johnson Brody D. , Burdisso Ricardo A.
Published: July 2002

In recent years, hybrid absorption systems have been implemented which achieve high sound absorption over a broad frequency range. This work is an experimental study of a broadband hybrid absorption system which is comprised of a layer of sound-absorbing material (the passive component) positioned at a distance from a movable wall (the active component) inside an impedance tube. The movable wall is used to impose desired boundary conditions in the cavity behind the passive layer, thereby increasing the absorption of the system at frequencies where the passive material is not independently effective. Both pressure-release (i.e., minimizing the pressure at the back surface of the layer) and impedance-matching (i.e., minimizing the reflected wave from the layer) boundary conditions are studied. The performance of the hybrid system for these two boundary conditions is compared for broadband disturbances over a frequency range of 100–1000 Hz. The unmodified passive system showed absorption coefficients greater than 0.7 only above 500 Hz, while the impedance-matching condition yielded absorption coefficients of 0.8 to 1.0 over the 100–1000-Hz range. The impedance-matching condition provided significantly better absorption than that achieved with the pressure-release condition. The sensitivity of these control approaches to system parameters is also investigated.
Kirchhoff evaluation of scattered elastic wavefields in anisotropic media
Authors: Spies Martin
Published: July 2002

Three-dimensional elastic wave scattering is addressed for the case of general anisotropic materials. For traction-free scatterers the elastodynamic Kirchhoff approximation is applied, which is valid at high frequencies and near specular angles. Based on a mathematical formulation including Green’s triadic stress tensor function, asymptotic evaluation yields the displacement vector of the scattered wavefield in a form which is convenient for effective numerical computation. The (point source) far-field approximation applied to Green’s triadic function is valid in noncaustic regions.
Influence of peripheral resolvability on the perceptual segregation of harmonic complex tones differing in fundamental frequency
Authors: Grimault Nicolas , Micheyl Christophe , Carlyon Robert P. , Arthaud Patrick , Collet Lionel
Published: July 2002

Two experiments investigated the influence of resolvability on the perceptual organization of sequential harmonic complexes differing in fundamental frequency (F0). Using a constant-stimuli method, streaming scores for ABA-… sequences of harmonic complexes were measured as a function of the F0 difference between the A and B tones. In the first experiment, streaming scores were measured for harmonic complexes having two different nominal F0s (88 and 250 Hz) and filtered in three frequency regions (a LOW, a MID, and a HIGH region with corner frequencies of 125–625 Hz, 1375–1875 Hz, and 3900–5400 Hz, respectively). Some streaming was observed in the HIGH region (in which the harmonics were always unresolved) but streaming scores remained generally lower than in the LOW and MID regions. The second experiment verified that the streaming observed in the HIGH region was not due to the use of distortion products. Overall, the results indicated that although streaming can occur in the absence of spectral cues, the degree of resolvability of the harmonics has a significant influence.
Experimental study of sound propagation in a flexible duct
Authors: Huang Lixi , Choy Y. S. , So R. M. C. , Chong T. L.
Published: July 2002

Propagation of sound in a flexible duct is investigated both theoretically and experimentally. Strong coupling of sound and flexural waves on the duct wall is found when the wall-to-air mass ratio is of the order of unity. The axial phase speed of sound approaches the in vacuo speed of flexural waves (subsonic in this case) at low frequencies. However, a speed higher than the isentropic sound speed in free space (340 m/s) is found beyond a critical frequency which is a function of the mass ratio. Experiments using a duct with a finite section of tensioned membrane are compared with the propagating modes pertaining to the infinite membrane model. Satisfactory quantitative agreement is obtained and the measured phase speed ranges from 8.3 to 1348 m/s. In the moderate frequency range, the theory predicts high spatial damping rate for the subsonic waves, which is consistent with the experimental observation that subsonic waves become increasingly undetectable as the frequency increases. Substantial sound reflection is observed at the interface between the rigid and the flexible segments of the duct without cross-section discontinuity, which, together with the high spatial damping, could form a basis for passive control of low-frequency duct noise.
Viscoelastic Response of a Cohesive Soil in the Frequency Domain
Authors: Kondner Robert L. , Ho Michael M. K.
Published: July 2002

Energy storage and energy dissipation characteristics of a cohesive soil are studied in the frequency domain using strain-controlled vibratory uniaxial compression tests. Such characteristics are important considerations in earthquake phenomena, machine foundation design, and soil-structure interaction under dynamic loading. The soil response is expressed in terms of the storage, loss, and complex moduli as well as the loss tangent. Dynamic stress-strain amplitude response is nonlinear even at small values of dynamic strain. Storage, loss, and complex moduli decrease with increased dynamic strain amplitude. The energy dissipation expressed in terms of the loss tangent decreases with increases in moisture content, frequency, and dynamic strain amplitude. Loss tangent values determined by the direct method are compared with those obtained by transformation of stress relaxation test data. Effects of concentration (moisture content) are presented in terms of a non-dimensional dynamic stress-strength parameter using the ultimate compressive strength in uniaxial compression as a consistency index. Static stress level about which the dynamic perturbations take place has no apparent effect on the dynamic stress-strain response for the range studied.
Chaotic rheological parameters of periodically forced suspensions of slender rods in simple shear flow
Authors: Kumar K. Satheesh , Ramamohan T. R.
Published: July 2002

We demonstrate for the first time that the rheological parameters like the apparent viscosities and the first and second normal stress differences of suspensions of orientable particles can show chaotic behavior when the orientation vector evolves chaotically. We also demonstrate that the range of the values of the rheological parameters is about 10 000 times greater when the parameters evolve chaotically. This suggests that a wide range of properties may be obtained by small variations in controllable parameters. When coupled with suitable control of chaos algorithms, a wide range of suspension behavior is thus possible since a chaotic solution can be considered as an unlimited reservoir of periodic solutions of arbitrary period.
Influence of elastic properties on drop deformation and breakup in shear flow
Authors: Mighri F. , Carreau P. J. , Ajji A.
Published: July 2002

In this article we report experimental results on the deformation and the critical breakup conditions of a single drop in a medium under simple shear flow. The role played by both drop and matrix elasticities is quantified by using constant viscosity elastic (Boger) fluids. The experiments were conducted using two transparent parallel disks mounted on a R-18 Weissenberg rheogoniometer. The critical shear rate was determined by imposing successive small changes in shear rate from lower to higher values until the drop breakup was observed. The results show remarkable differences in the mode of deformation and breakup for Newtonian and elastic fluid systems. It is also found that the drop resistance to deformation and breakup increases with increasing elasticity ratio. The contribution of the drop and matrix elasticities is quantified by using an empirical relation established between the drop deformation and the capillary number, Ca. The critical breakup conditions, such as a dimensionless breakup time, tb*, and a critical capillary number, Cac, are determined as a function of the drop/matrix elasticity ratio, k′. The values of Cac and tb* are found to increase with increasing k′.
Powder diffraction study of LiCu2O2 crystals
Authors: Paszkowicz W. , Marczak M. , Vorotynov A. M. , Sablina K. A. , Petrakovskii G. A.
Published: July 2002

LiCu2O2 crystals grown by spontaneous crystallization from the fluxed melt were studied by powder X-ray diffraction. The phase analysis shows that the applied growth conditions are suitable for preparation of a single-phase compound. The as-grown crystals contain only traces of foreign phases (Li2CuO2, CuO, Cu2O) typical for preparation of the LiCu2O2 compound. Attempts to anneal or quench the as-grown crystals led to two-phase samples containing LiCu2O2 and LiCu3O3. X-ray powder diffraction pattern of a LiCu2O2 crystal is reported and compared with literature data. The crystal structure is orthorhombic, space group Pnma, in agreement with literature data. Lattice parameters of the studied sample are a=5.7286(2) Å, b=2.8588(1) Å, and c=12.4143(3) Å. Time evolution of a diffraction pattern illustrates a slow increase of the secondary-phases contribution assumed to be due to interaction of the powdered crystal with humid air. A brief summary of compounds known in the Li–Cu–O system is included
Study on influence of air cleaner on room dispersion field and its optimal placement using adjoint concentration
Authors: Kikumoto Hideki , Ooka Ryozo
Published: November 2022

Based on the assumption of a nonuniform pollutant concentration distribution and stochastic determination of pollutant sources and receptors in indoor space, this study shows how to formulate the expected pollutant concentration observed by the receptors in the presence of an air cleaner, using adjoint concentration and parameters related to probability of pollutants passing through the cleaner. Using this formulation, the structure of the concentration reduction effect of the cleaner and its optimal placement are discussed. The studies with the formulation are also conducted under the assumption of instantaneous uniform diffusion and for a problem in one‐dimensional space.
Metabolic Recycling Enhances Proliferation in MYC‐Transformed Lymphoma B Cells
Authors: Zhang Cissy , Hoang Giang , Attarwala Nabeel , Cooper Arthur J. L. , Asaka Ryoichi , Le Anne
Published: November 2022

Relapses negatively impact cancer patient survival due to the tumorigenesis ability of surviving cancer cells post‐therapy. Efforts are needed to better understand and combat this problem. This study hypothesized that dead cell debris post‐radiation therapy creates an advantageous microenvironment rich in metabolic materials promoting the growth of remaining live cancer cells. In this study, live cancer cells are co‐cultured with dead cancer cells eradicated by UV radiation to mimic a post‐therapy environment. Isotopic labeling metabolomics is used to investigate the metabolic behavior of cancer cells grown in a post‐radiation‐therapy environment. It is found that post‐UV‐eradicated dead cancer cells serve as nutritional sources of “off‐the‐shelf” and precursor metabolites for surviving cancer cells. The surviving cancer cells then take up these metabolites, integrate and upregulate multiple vital metabolic processes, thereby significantly increasing growth in vitro and probably in vivo beyond their intrinsic fast‐growing characteristics. Importantly, this active metabolite uptake behavior is only observed in oncogenic but not in non‐oncogenic cells, presenting opportunities for therapeutic approaches to interrupt the active uptake process of oncogenic cells without affecting normal cells. The process by which living cancer cells re‐use vital metabolites released by dead cancer cells post‐therapy is coined in this study as “metabolic recycling” of oncogenic cells.
Direct Visualization of Magnetic Correlations in Frustrated Spinel ZnFe2O4
Authors: Sandemann Jonas Ruby , Grønbech Thomas Bjørn Egede , Støckler Kristoffer Andreas Holm , Ye Feng , Chakoumakos Bryan C. , Iversen Bo Brummerstedt
Published: November 2022

Magnetic materials with the spinel structure (A2+B3+2O4) form the core of numerous magnetic devices, and ZnFe2O4constitutes a peculiar example where the nature of the magnetism is still unresolved. Susceptibility measurements revealed a cusp aroundTc = 13 K resembling an antiferromagnetic transition, despite the positive Curie–Weiss temperature determined to be ΘCW = 102.8(1) K. Bifurcation of field‐cooled and zero‐field‐cooled data belowTcin conjunction with a frequency dependence of the peak position and a non‐zero imaginary component belowTcshows it is in fact associated with a spin‐glass transition. Highly structured magnetic diffuse neutron scattering from single crystals develops between 50 K and 25 K revealing the presence of magnetic disorder which is correlated in nature. Here, the 3D‐mΔPDF method is used to visualize the local magnetic ordering preferences, and ferromagnetic nearest‐neighbor and antiferromagnetic third nearest‐neighbor correlations are shown to be dominant. Their temperature dependence is extraordinary with some flipping in sign and a strongly varying correlation length. The correlations can be explained by orbital interaction mechanisms for the magnetic pathways and a preferred spin cluster. This study demonstrates the power of the 3D‐mΔPDF method in visualizing complex quantum phenomena thereby providing a way to obtain an atomic‐scale understanding of magnetic frustration.
Switchable Polyacrylonitrile‐Copolymer for Melt‐Processing and Thermal Carbonization—3D Printing of Carbon Supercapacitor Electrodes with High Capacitance
Authors: Usselmann Michael , Bansmann Joachim , Kuehne Alexander J. C.
Published: November 2022

Polyacrylonitrile (PAN) represents the most widely used precursor for carbon fibers and carbon materials. Carbon materials stand out with their high mechanical performance, but they also show excellent electrical conductivity and high surface area. These properties render carbon materials suitable as electrode material for fuel cells, batteries, and supercapacitors. However, PAN has to be processed from solution before being thermally converted to carbon, limiting its final format to fibers, films, and non‐wovens. Here, a PAN‐copolymer with an intrinsic plasticizer is presented to reduce the melting temperature and avoid undesired entering of the thermal carbonization regime. This plasticizer enables melt extrusion‐based additive manufacturing (EAM). The plasticizer in the PAN‐copolymer can be switched to increase the melting temperature after processing, allowing the 3D‐melt‐printed workpiece to be thermally carbonized after EAM. Melt‐processing of the PAN copolymer extends the freedom‐in‐design of carbon materials to mold‐free rapid prototyping, in the absence of solvents, which enables more economic and sustainable manufacturing processes. As an example for the capability of this material system, open meshed carbon electrodes are printed for supercapacitors that are metal‐ and binder‐free with an optimized thickness of 1.5 mm and a capacitance of up to 387 mF cm−2.
Observation of Plasmoelectric Effect in Plasmonic Zirconium Nitride
Authors: Ishii Satoshi , Yu Min‐Wen , Chen Kuo‐Ping , Nagao Tadaaki
Published: November 2022

A plasmonic nanostructure forming a metal‐semiconductor interface generates electric potential by optical illumination. Grounded plasmonic nanostructures can also generate electric potentials based on the recently demonstrated plasmoelectric effect that allows all metallic photoelectric devices to be fabricated and is capable of generating negative and positive potentials at off‐resonance by merely tuning the illumination wavelength. However, to date, the plasmoelectric effect has been observed only with gold and silver. In this study, the generation of plasmoelectric effect by zirconium nitride (ZrN) is experimentally demonstrated, which is a nonmetallic plasmonic material. The Kelvin probe force microscope measurements demonstrate that ZrN nanodisk arrays fabricated through e‐beam lithography and dry etching exhibit characteristic potential sign changes of the plasmoelectric potential. The features of the wavelength‐dependent potential shifts in the experiments agree with the numerical calculations. It is anticipated that the plasmoelectric effect can be observed in other non‐metallic plasmonic materials and these studies may lead to robust photoelectric devices working at off‐resonances.
Structurally Tailored Hierarchical Cu Current Collector with Selective Inward Growth of Lithium for High‐Performance Lithium Metal Batteries
Authors: Yang Inyeong , Jeong Ji‐hun , Seok Jae Young , Kim Sanha
Published: November 2022

Li‐metal is gaining attention as a next generation anode active material, of which the primary attribute is its energy density. However, Li dendrite formation is the primary challenge. Herein, a design strategy with increased structural dimensions and hierarchy for Li‐metal anode is investigated to stabilize the dendrite formation for extending the cycle life with high reversibility. For this, diverse structural current collectors (CCs) are fabricated by manipulating structural design in different length scales and characterized as a Li‐metal anode. The hierarchy (i.e., nanostructures inside the microcavities) can not only reduce the current density on entire anode surface but also concentrate the local electrical field onto inner surfaces of the microstructures, inducing preferential Li nucleation inside microcavities and promoting confined growth of Li. It is confirmed that introduction of structural hierarchy can enhance the cycle life by 364% and the preservation of coulombic efficiency > 90% by 266%. The design strategy is extended by exploring a practical one‐step fabrication of the hierarchical CC with even greater performance via the inward growth mechanism. This work elucidates the mechanism of inward Li growth using tailored surface geometries for Li dendrite suppression, which can be a guideline for designing structured anode CCs for Li‐metal batteries.
Fish seed and feed value chains analysis and their critical factors for aquaculture development in Tanzania
Authors: Shoko Amon Paul , Limbu Samwel Mchele , Ulotu Eusebia Ernest , Shayo Salome Daniel , Silas Mathew Ogalo , Chimatiro Sloans K. , Madalla Nazael Amos , Tamatamah Rashid Adam
Published: November 2022

Seeds and feeds are among the most important inputs required for sustainable aquaculture industry development in any country worldwide. However, the value chain analysis of seeds and feeds in most developing countries including Tanzania has not been mapped, and the key actors are not identified and characterized. To address this knowledge gap, we mapped the fish seed and feed value chains in Morogoro, Dar es Salaam, Coast and Lindi regions in Tanzania, evaluated their performances, analyzed their contributions to aquaculture growth and finally assessed the critical factors impending aquaculture development before proposing appropriate strategies for upgrading. We found that the fish seed value chain comprised broodstock suppliers, seed producers, seed marketers, traders and fish farmers. Tilapia (Oreochromis sp.) and African sharptooth catfish (Clarias gariepinus) seeds produced were primarily sold to farmers at an advanced fry stage (1 to 5 g) at a price ranging from USD 0.09 to 0.13 and USD 0.22 to 0.27, respectively. The feed value chain consisted of suppliers, producers, importers, traders and fish farmers. The feeds produced were powdered, compressed and extruded pellets and granules sold at an average price of USD 2.50/kg. The seed and feed value chains in the four regions drive the aquaculture development and employ 137 and 109 people, respectively. The fish farming was mainly affected by insufficient seeds and feeds; inadequate extension services, inadequate technical skills in seed and feed production; limited farming equipment; insufficient capital and limited access to market. We propose increasing seed and feed production through collaborative research between researchers and the private sector, enhancing delivery of extension services to all fish farmers, providing fiscal incentives to hatchery and feed investors, organizing hatchery owners into associations, and undertaking marketing awareness campaign for aquaculture growth in the country for food, income and employment generation.
Continuous flow photocatalytic reactor using TiO2‐coated foams, modeling and experimental operating mode
Authors: Goetz Vincent , Dezani Chloé , Ribeiro Enrique , Caliot Cyril , Plantard Gael
Published: November 2022

This article aims to build a modeling and simulating tool of the operation of a continuous flow heterogeneous photocatalysis reactor. Continuous flow is well‐known in reactor engineering for allowing advanced control of reactor and scaling‐up with great confidence, but little research has addressed it's potential for this kind of application. In developing this model, particular attention was paid to the coupling which occurs at local scale between the radiative transfer and the reaction kinetics of advanced oxidation of a target organic micro‐pollutant. The solution of the radiative transfer equation by Monte Carlo method was applied to a photocatalyst supported on a macroporous ceramic foam forming an efficient 3D support. After identification of the kinetic law of degradation, the dynamic simulation model was validated through comparison with a series of experiments performed for different but constant irradiations and for variable irradiations approaching, in term of intensity and dynamics, natural solar radiation.
Modulating acid site spatial location of Zn/ZSM‐5 catalyst to boost the stable aromatization of hexane
Authors: Yan Hao , Ren Delun , Li Zhiqiang , Chen Junshu , Zhang Xinyang , Wang Yanhao , Duan Gongzheng , Feng Xiang , Zhou Xin , Liu Yibin , Chen Xiaobo , Yang Chaohe
Published: November 2022

Engineering acid site spatial location of zeolite catalyst harbors tremendous potential to boost catalytic performance but still remains a grand challenge for aromatization reaction. Herein, we successfully manipulate acid site spatial location inside the ZSM‐5 channels to promote the hexane aromatization via the simple SiO2 coating treatment. Multi‐techniques demonstrated that the medium strong L acid in the channel originated from the Si(Al)OZn structure is mainly retained in the Zn/ZSM‐5‐Si catalyst by covering the acid sites outside the channel. Surprisingly, there is a good linear relationship between BTEX yield and this medium strong L acid content. Based on the reaction kinetics, in situ FT‐IR and theoretical calculations, it is found that the L acid with confinement effect served as the main active site could prominently enhance the cyclization of propene intermediate and the dehydrogenation of cycloalkane due to the strong affinity between the C/H and ZnOx, and control the desorption of BTEX (mainly benzene, toluene, ethylbenzene, and p‐xylene) by weakening the binding of hydrogen proton to π electrons. Compared with the ordinary Zn/ZSM‐5 catalyst, the yield of BTEX is increased by nearly 10%, and the Zn/ZSM‐5‐Si catalyst exhibits excellent anti coking deactivation ability. This strategy together with mechanistic results may pave the rational design of efficient Zn/ZSM‐5 catalysts for aromatization reaction.
Identification of causal effects of neuroanatomy on cognitive decline requires modeling unobserved confounders
Authors: Pölsterl Sebastian , Wachinger Christian ,   the Alzheimer's Disease Neuroimaging Initiative,   the Japanese Alzheimer's Disease Neuroimaging Initiative
Published: November 2022

Introduction

Carrying out a randomized controlled trial to estimate the causal effects of regional brain atrophy due to Alzheimer's disease (AD) is impossible. Instead, we must estimate causal effects from observational data. However, this generally requires knowing and having recorded all confounders, which is often unrealistic.

Methods

We provide an approach that leverages the dependencies among multiple neuroanatomical measures to estimate causal effects from observational neuroimaging data without the need to know and record all confounders.

Results

Our analyses of subjects from the Alzheimer's Disease Neuroimaging Initiative demonstrate that using our approach results in biologically meaningful conclusions, whereas ignoring unobserved confounding yields results that conflict with established knowledge on cognitive decline due to AD.

Discussion

The findings provide evidence that the impact of unobserved confounding can be substantial. To ensure trustworthy scientific insights, future AD research can account for unobserved confounding via the proposed approach.
Suitability of Natura 2000 sites for threatened freshwater species under projected climate change
Authors: Basen Timo , Chucholl Christoph , Oexle Sarah , Ros Albert , Brinker Alexander
Published: November 2022

As part of the world's largest coordinated network of protected areas, Natura 2000, European Union member states designate special areas of conservation (SACs) to maintain or achieve favourable conservation status for imperilled aquatic species listed under Annex II of the Habitats Directive. Long‐term suitability of SAC habitats is potentially challenged by continuing climate change.

To examine this emerging threat to aquatic species conservation, the habitat suitability of designated SACs (n = 8,221) for 24 Central European freshwater species (18 teleosts, two lampreys, two crayfish and two bivalves) was assessed under current and projected end‐of‐century climate using environmental niche models calibrated on species occurrences reported under the Habitats Directive (n = 33,995). Potential future conditions included three climate‐change scenarios representing a gradient from effective climate protection measures to a worst‐case warming scenario.

Habitat suitability of SACs was consistently calculated as high under present climate but projected to decline severely for two‐thirds of the species under future climate conditions, with the magnitude of decline generally paralleling that of projected climate change. Under high emission scenarios, one third to more than half of the species were predicted to face unsuitable conditions in ≥75% of SACs. Predicted change in habitat suitability varied across biogeographical regions, with Alpine SACs often undergoing lower or no decline in predicted suitability.

Given the discrepancy between the location of currently designated SACs and predicted areas of suitable habitat under projected end‐of‐century climate, climate change can be expected to undermine the long‐term effectiveness of currently protected areas. Fostering climate resilience of freshwater habitats within SACs, restoring stream connectivity among SACs, assisted migration to newly suitable SACs where natural dispersal is not possible, as well as designation of new protected areas within climate refugia represent key actions to overcome this potential future conservation gap.
Nanostructured Assembly of Magnetic and Plasmonic Nanoparticles Transferred from AOT Winsor Phases to Oil‐in‐Water Functional Dispersions
Authors: Fortes Martín Rebeca , Prietzel Claudia , Koetz Joachim
Published: November 2022

Nanoparticle interactions can mediate assemblies and self‐organization into colloidal superstructures, if then control of the size and stabilization is highly required towards the fabrication of functional nanomaterials. In the proposed approach, different types of water‐dispersible and oil‐dispersible nanoparticles were incorporated in water‐in oil (w/o) microemulsions stabilized by Aerosol‐OT (AOT) as surfactant. Phase separation at higher surfactant and water contents resulted in the formation of a heterocoagulate, which can be separated with an external magnet. This magnetic heterocoagulate, which can contain 3 different types of nanoparticles, can be dispersed in longer‐chain carboxylic acids. An additional phase‐transfer into oil‐in water (o/w) dispersions was mediated by an auxiliary surfactant in water‐ethanol. The resulting nanostructures from heterocoagulates formed at higher temperatures consisted on inner domains of water‐dispersible nanoparticles embedded in a matrix‐shell of oleyl‐capped nanoparticles. Thus, a new encapsulation strategy is achieved under relative mild conditions, combining three types of nanoparticles and providing compartmentalization and magnetic‐responsiveness.
Epstein–Barr virus detection in endoscopic submucosal dissection‐proven early gastric cancer with mixed‐type histology
Authors: Yanai Hideo , Chihara Daisuke , Harano Megumi , Sakaguchi Eiki , Kaino Seiji , Murakami Tomoyuki , Nishikawa Jun
Published: November 2022

Backgrounds

Early gastric cancer (EGC) with mixed‐type histology is a significant risk factor for additional surgery after endoscopic submucosal dissection (ESD). On the other hand, Epstein–Barr virus‐associated gastric cancer (EBVaGC) with mixed‐type histology is a favorable risk factor with regard to lymph node metastasis.

Methods

We performed EBV detection in 13 ESD‐proven lesions in 13 cases of early gastric cancer with mixed‐type histology using EBV‐encoded small RNA1 in situ hybridization (EBER1 ISH).

Results

EBVaGC was diagnosed in only one (7.7%) of the tested lesions. That EBVaGC patient underwent surgery and there was no residual lesion and no lymph metastasis. EBVaGC is not frequent in EGC with mixed‐type histology.

Conclusions

EBV testing of gastric biopsy specimens seems not to be useful to predict the mixed‐type histology results of ESD. However, EBV testing for ESD specimens of EGC with mixed‐type histology is expected to be useful for avoiding excessive additional surgery.
Automated heuristic based context dependent ETL process to generate multi‐dimensional model for tabular data
Authors: Hira Swati , Deshpande Parag S.
Published: November 2022

Over the past decade, enterprises have broadly adopted data warehousing in various activities. Today, abundant information is available on websites in the form of tables or spreadsheets. This huge amount of data cannot be processed directly because of its complexity, heterogeneity, and gap between user requirements. In this work, an automatic approach is proposed to build the multi‐dimensional structure (MDS) of heterogeneous tabular data format for intelligent decision‐making. The proposed MDS is generated by identifying components such as dimensions and hierarchies. It automatically extracts measures based on the spatial characteristics of data dimensions like region, time as well as their hierarchies. This proposed approach automatically generates a multi‐dimensional model for BI tools without complicated ETL (Extraction, Transformation and Loading) process and helps to solve several business queries, like “Top 5 states in India based on Irrigated area in 2009”. Moreover, the proposed method reduces the time and cost of building multi‐dimensional models to a very large extent. The correctness of proposed method is tested with the synthetic and economic datasets of Government websites where information is stored in tabular formats and various heterogeneous setups where the proposed method saved approximately 4000 to 5000 computing hours of the ETL process.