bluuebunny/crossref_metadata_2025 huggingface dataset:
The detection of tethered and rising bubbles using multiple acoustic techniques
Authors: Leighton Timothy G. , Ramble David G. , Phelps Andy D.
Published: July 2002

There exists a range of acoustic techniques for characterizing bubble populations within liquids. Each technique has limitations, and complete characterization of a population requires the sequential or simultaneous use of several, so that the limitations of each find compensation in the others. Here, nine techniques are deployed using one experimental rig, and compared to determine how accurately and rapidly they can characterize given bubble populations. These are, specifically (i) two stationary bubbles attached to a wire; and (ii) injected, rising bubbles.
Comparison of methods for determining specific acoustic impedance
Authors: Jones Michael G. , Stiede Patricia E.
Published: July 2002

An investigation was conducted to explore potential improvements provided by alternate implementations of two impedance-measurement methods, known as the two-microphone and multipoint methods. This investigation is part of a continuing technology development to find more efficient and convenient methods for impedance measurements in harsh environments at high frequencies. The two alternate methods are compared with other methods to determine relative merits. As expected, the “best method” depends upon trade-offs between convenience and accuracy. The single-microphone method eliminates one of the two microphones typically used in the two-microphone method. The single-microphone method should be useful where mechanical constraints allow only one microphone to be placed into the test environment. It is found to be quite accurate with a single discrete frequency source, but the most inaccurate with a random noise source. An alternate implementation of the multipoint method, achieved by replacing the single-tone source with a pseudo-random noise source, requires significantly less time with minimal loss of accuracy. Typical agreement between this implementation and the accepted standard is within 0.1 ρc units. However, slightly larger deviations at frequencies above 2.5 kHz indicate challenges in the proposed extension to high-frequency (up to 25-kHz) applications.
Otoacoustic emissions, hair cells, and myosin motors
Authors: Manley Geoffrey A. , Gallo Lothar
Published: July 2002

The stereovillar bundles of hair cells show active movements that may be generated by the putative myosin–actin interactions underlying hair-cell adaptation. Such movement is a possible candidate for the generation of spontaneous otoacoustic emissions (SOAE) in the ear canal of nonmammals. In the basilar papilla of certain lizard families, most hair cells are not coupled by a tectorial membrane, making it easier to assign the energy in emission peaks to defined groups of hair cells. We have studied 62 SOAE in the Bahamian Anole Anolis sagrei, which has about 140 hair cells with “free-standing” bundles in the high-frequency area of its papilla. Individual SOAE peaks were traced to between 3 and 38 hair cells, and the mean power output per hair cell was calculated to be 141 aW. The number of bundle myosins putatively involved in the generation of each SOAE was estimated and the force generated by each myosin at 1 kHz calculated to be approximately 0.1 pN. The data support the idea that hair cells generate emissions and suggest that myosin produces sufficient power to be the emission motor.
The splitting of dispersion curves for plates fluid-loaded on both sides
Authors: Bao X. L. , Franklin H. , Raju P. K. , Überall H.
Published: July 2002

For in vacuo elastic plates or plates fluid-loaded on one side, it has been previously shown that dispersion curves for both plate-borne (Lamb) type and, in the latter case, also fluid-borne (Scholte–Stoneley) type fail to cross but repel each other, with the waves simultaneously exchanging their physical character. This study is extended here to the case of a plate loaded by two different fluids, where a quantitative calculation of dispersion curves for water on one side, and a lighter or a heavier fluid on the other, is carried out confirming the existence of two different Scholte–Stoneley waves.
A descriptive model of the receptor potential nonlinearities generated by the hair cell mechanoelectrical transducer
Authors: Lukashkin Andrei N. , Russell Ian J.
Published: July 2002

This paper describes a model for generating the hair cell receptor potential based on a second-order Boltzmann function. The model includes only the resistive elements of the hair cell membranes with batteries across them and the series resistance of the external return path of the transducer current through the tissue of the cochlea. The model provides a qualitative description of signal processing by the hair cell transducer and shows that the nonlinearity of the hair cell transducer can give rise to nonlinear phenomena, such as intermodulation distortion products and two-tone suppression with patterns similar to those which have been recorded from the peripheral auditory system. Particular outcomes of the model are the demonstration that two-tone suppression depends not on the saturation of the receptor current, but on the behaviour of the hair cell transducer function close to the operating point. The model also shows that there is non-monotonic growth and phase change for any spectral component, but not for the fundamental of the receptor potential.
The detection and dimension of bubble entrainment and comminution
Authors: Leighton T. G. , White P. R. , Schneider M. F.
Published: July 2002

Data on bubble entrainment and comminution are gathered in three experiments, involving the breakup of a disk of air trapped between two plates, and bubble cloud generation under a waterfall, and a plunging jet. In the second two cases, an automated acoustic system for characterizing the entrainment is employed. The data sets are compared with an existing theory for bubble fragmentation, in which a key parameter is the number of spatial dimensions associated with the insertion of randomly positioned planes which are used to divide up the bubble. While an appropriate best-fit theoretical curve can be obtained for the bubble population histograms generated by air disk comminution, waterfalls and plunging jets produce multimodal distributions which the theory cannot model. The differing roles of shape oscillations and surface waves in bubble fragmentation, and the issues involved with incorporating these into the model, are examined.
Measurements of the travel-time bias caused by internal waves
Authors: Dzieciuch Matthew ,   the AST Group
Published: July 2002

Theoretical work and computer simulations predict that the travel-time of acoustic signals is biased by the ocean internal wave field. The path integral theory for scattering predicts that the size of the travel time bias depends on the logarithm of the center frequency of the acoustic signal. A recent experiment, in which two acoustic signals with different center frequencies were transmitted simultaneously, makes it possible to measure the bias experimentally. Preliminary results suggest that the bias is about 50 ms at 3500-km range, which is roughly as large as expected. a)The AST group is T. G. Birdsall (U. Michigan), B. M. Howe (U. Washington), J. A. Mercer (U. Washington), K. Metzger (U. Michigan), R. C. Spindel (U. Washington), and P. F. Worcester (SIO).
Acoustic anisotropy in bovine cancellous bone
Authors: Hosokawa A. , Otani T.
Published: July 2002

This paper presents the experimental results on the acoustic anisotropy in bovine cancellous bone. The propagation of both fast and slow longitudinal waves in bovine cancellous bone was experimentally examined in relation to the structural anisotropy, or the trabecular arrangement. Propagation speeds of the fast and slow waves were measured as a function of the propagation angle to the trabecular alignment, and theoretically estimated by use of Biot’s theory for an isotropic medium.
Source signature measurements of underwater explosives at very high ambient pressures
Authors: Collins John A. , Broda James E. , Purdy G. M. , Gaspin Joel , Griffin Tom , Peletski Carl , Lipton Len , Baudler Bryan
Published: July 2002

The interpretation of seismic refraction experiments carried out on the deep-ocean floor has been hampered by lack of knowledge of the source signatures of explosives at these high ambient pressures. In order to fully exploit the data from such experiments, the source signatures of four explosives detonated at deep water depths have been measured. The explosives were commercially available Pentolite and three U.S. Navy explosives: PBXN-103, PBXN-111, and PBXW-127. A total of 75 ∼10 lb (4.54 kg) charges were detonated at depths of 2350–4593 m, and the source signatures were recorded at offset ranges of 160–230 m. For all four explosives, the period of the first oscillation follows the theoretically established relationship T=K*M1/3(Z+10)−5/6, where T is the period (s), M is the charge mass (kg), and Z is the detonation depth (m). The optimum value of K for Pentolite (2.07±0.01 s m5/6 kg−1) is identical to the value previously reported from the analysis of explosives detonated at depths of less than a few hundred meters. The optimum values for PBXN-103, PBXN-111, and PBXW-127 are 2.67±0.01 s m5/6 kg−1, 2.64±0.01 s m5/6 kg−1, and 2.73±0.01 s m5/6 kg−1, respectively. The greater bubble pulse period of the PBX-based explosives means that they are richer in low-frequency energy than Pentolite. The total energy flux in the frequency band 30–100 Hz is ∼6 dB greater for the PBX-based explosives than that for Pentolite at all detonation depths.
Correlated amplitude fluctuations of spontaneous otoacoustic emissions
Authors: van Dijk Pim , Wit Hero P.
Published: July 2002

The frequency spectrum of a spontaneous otoacoustic emission (SOAE) recording may contain multiple narrow peaks. These peaks correspond to multiple SOAEs emitted by the inner ear. The individual SOAEs exhibit small amplitude fluctuations. The correlation between the amplitude fluctuations of multiple SOAEs in an individual ear was studied in 19 SOAE recordings from humans. For 424 pairs of SOAEs, the normalized amplitude cross-correlation function was computed. Significant correlation was found in 63 pairs (15%): 34 pairs showed positive and 29 pairs showed negative correlation. Some SOAE pairs were part of an equally spaced triplet of emission peaks, with one SOAE apparently generated as a distortion product of the other two “primary” SOAEs. The occurrence of correlation between a distortion product SOAE and a “primary” SOAE was 56%. This is significantly higher than the occurrence of correlation for the entire set of SOAE pairs. In addition, the spectral width of the distortion product SOAE was correlated with the spectral width of the “primary” SOAEs (R=0.87, p<10−6). For 79% of the correlated SOAE pairs, the cross-correlation function peaked at positive time delay. This indicates that for these pairs the fluctuation of the lower frequency emission lagged the fluctuation of the higher frequency emission. The average peak delay was 11.0 ms (s.d. 22.1 ms). The results demonstrate that interactions between SOAEs in an individual ear frequently occur and are asymmetrical.
Model experiment to study sonic boom propagation through turbulence. Part II. Effect of turbulence intensity and propagation distance through turbulence
Authors: Lipkens Bart , Blackstock David T.
Published: July 2002

A model experiment was reported to be successful in simulating the propagation of sonic booms through a turbulent atmosphere [B. Lipkens and D. T. Blackstock, J. Acoust. Soc. Am. 103, 148–158 (1998)]. In this study the effect on N wave characteristics of turbulence intensity and propagation distance through turbulence are investigated. The main parameters of interest are the rise time and the peak pressure. The effect of turbulence intensity and propagation distance is to flatten the rise time and peak pressure distributions. Rise time and peak pressure distributions always have positive skewness after propagation through turbulence. Average rise time grows with turbulence intensity and propagation distance. The scattering of rise time data is one-sided, i.e., rise times are almost always increased by turbulence. Average peak pressure decreases slowly with turbulence intensity and propagation distance. For the reported data a threefold increase in average rise time is observed and a maximum decrease of about 20% in average peak pressure. Rise times more than ten times that of the no-turbulence value are observed. At most, the maximum peak pressure doubles after propagation through turbulence, and the minimum peak pressure values are about one-half the no-turbulence values. Rounded waveforms are always more common than peaked waveforms.
A new calculation procedure for spatial impulse responses in ultrasound
Authors: Jensen Jo/rgen Arendt
Published: July 2002

A new procedure for the calculation of spatial impulse responses for linear sound fields is introduced. This calculation procedure uses the well known technique of calculating the spatial impulse response from the intersection of a circle emanating from the projected spherical wave with the boundary of the emitting aperture. This general result holds for all aperture boundaries for a flat transducer surface, and is used in the procedure to yield the response for all types of flat transducers. An arbitrary apodization function over the aperture can be incorporated through a simple one-dimensional integration. The case of a soft baffle mounting of the aperture is also included. Specific solutions for transducer boundaries made from lines are given, so that any polygon transducer can be handled. Specific solutions for circles are also given. Finally, a solution for a general boundary is stated, and all these boundary elements can be combined to, e.g., handle annular arrays or semi-circle transducers. Results from an implementation of the approach are given and compared to previously developed solutions for a simple aperture, a complex aperture, and a Gaussian apodized circular transducer.
Transducer field modeling in anisotropic media by superposition of Gaussian base functions
Authors: Spies Martin
Published: July 2002

Anisotropic structural materials like fiber composites, but also columnar-grained stainless steels, raise considerable problems for ultrasonic inspection due to the well-known wave propagation phenomena of skewing, splitting and distortion. In this respect, simulation and optimization in ultrasonic nondestructive testing have gained a considerable importance. Among a variety of methods for transducer field calculation, beam superposition has proven to be highly efficient. In this article, a Gaussian beam approach for anisotropic media is presented. The Gaussian base functions are obtained from relationships previously derived for Gaussian wave packets. Each function is furnished with coefficients fixing the beam waists and their position. To test the approach, the case of a piston radiator is addressed for general transversely isotropic media. Using Gaussian beam superposition instead of—as a reference—applying a point source superposition technique leads to an enormous reduction in computer run time.
ATOC or Candide: Toward depth-averaged temperature maps of the North Pacific Ocean
Authors: Dushaw Brian D. ,   ATOC Group
Published: July 2002

The ATOC Project has aquired trans-Pacific acoustic data from two acoustic sources: one located on Pioneer Seamount off the coast of California, the other located north of Kauai, Hawaii. Transmissions from these sources are detected by U.S. Navy SOSUS arrays located throughout the North Pacific. The time series of acoustic travel times from the Pioneer Seamount and Kauai transmissions are about 1 1/2 and 1 year long, respectively. Both time series have highly irregular sampling because of marine mammal protocols and temporary cable failures. These acoustic data are used to estimate ocean temperature accurately. At the time of writing this abstract, however, the overlap of the two time series is just beginning. The overlapping time series will for the first time allow estimates of temperature maps of the North Pacific basin using long-range acoustics because the acoustic paths from these sources criss-cross the North Pacific. This talk will show the initial maps of depth-averaged temperature of the North Pacific Ocean derived using the time series to be collected through Fall 1998. a)The Acoust. Thermometry of Ocean Climate (ATOC) Group is: A. B. Baggeroer, D. Menememlis [now at JPL], and C. Wunsch (MIT); T. G. Birdsall, K. Metzger (Univ. of Michigan); C. Clark (Cornell Univ.); J. A. Colosi (WHOI); B. D. Cornuelle, M. Dzieciuch [now at ABMF], W. Munk, P. F. Worcester (SIO); D. Costa (Univ. of California, Santa Cruz); B. D. Dushaw, B. M. Howe, J. A. Mercer, R. C. Spindel (APL-UW); A. M. G. Forbes (CSIRO, Hobart).
On the Numerical Determination of Relaxation and Retardation Spectra for Linearly Viscoelastic Materials
Authors: Clauser John F. , Knauss Wolfgang G.
Published: July 2002

Knowledge of the relaxation spectrum is important because (1) it provides an intrinsic characterization of the mechanical properties for linearly viscoelastic materials and (2) it offers a rational way to derive the coefficients for a Prony or Dirichlet series representation of the relaxation modulus of importance to some engineering analyses. A numerical solution based on Simpson quadrature leads to an unstable solution in the sense that a decrease in integration intervals produces a progressively worse solution which oscillates between positive and negative values. This difficulty may be overcome by requiring that the curvature of the relaxation spectrum with respect to the relaxation times be minimized. The method is tested on the modified power law and good agreement with the exact and numerically determined relaxation spectrum is obtained. However, when the same method is used to determine the retardation spectrum, only the unstable solution is obtained, although the form of the integral equation is the same. This different behavior is attributed to the difference in the characteristics of the relaxation and retardation spectral functions.
Linear viscoelastic properties of ordered latices
Authors: van der Vorst B. , van den Ende D. , Mellema J.
Published: July 2002

The frequency-dependent behavior of the storage modulus G′ and loss modulus G″ has been measured for an ordered latex at different volume fractions. From these measurements the volume fraction dependency of the static shear modulus was obtained. The theoretical static shear modulus has been deduced from a stress tensor expression which only takes into account the electrostatic pair interactions between nearest neighbors. The electrostatic pair interaction is modeled adequately to account for the multiparticle environment of a particle and for high surface charges. The interactions are described by the linear superposition approximation for the pair interaction energy between two particles given by Bell et al. [J. Colloid Interface Sci. 33, 335 (1970)]. The apparent surface potential and the effective Debije screening length used in this expression are determined from the electrostatic potential which is numerically determined from the Poisson–Boltzmann equation in a spherical cell. The theoretical model is also compared with measurements of several other investigators. Most of the experimental data can be scaled to a single mastercurve resulting from the proposed theoretical model.
Effects of molecular weight distribution on dynamic viscoelasticity and biaxial extensional flow behavior of polystyrene melts
Authors: Ebrahimi N. Golshan , Takahashi M. , Araki O. , Masuda T.
Published: July 2002

Dynamic viscoelasticity and biaxial extensional flow behavior of polystyrene melts with various molecular weight distributions have been studied in wide ranges of temperature and strain rate ε̇B. Two patterns of time dependence of the biaxial stress growth coefficient η+B are observed with increasing reduced strain rate ε̇Bτ0, where τ0 is a characteristic relaxation time. At short times, η+B coincides with the linear viscoelastic curve; then it shows strain hardening after that, or strain softening followed by a quasisteady state. These behaviors are observed for polydisperse polystyrenes at much higher ε̇Bτ0 than those for monodisperse polystyrenes. The quasisteady-state viscosity ηB,qs decreases with the strain rate. Addition of a very high molecular weight component causes considerable effects on τ0 and on the strain rate dependences of shear ‖η*‖ and biaxial ηB,qs viscosities as well as on the stress growth coefficient η+B, where ‖η*‖ is the absolute value of the complex viscosity. The relaxation time τ0 increases very much, and the strain rate dependences of ‖η*‖ and ηB,qs become much weaker. The upturn tendency of η+B becomes prominent when compared at the same reduced strain rate ε̇Bτ0. On the other hand, when compared at the same value of the reduced viscosity ηB,qs/6η0, a similar degree of strain softening in η+B is observed for all polydisperse samples, where η0 is the zero shear viscosity.
Sb2Se3 Thin‐Film Solar Cells Exceeding 10% Power Conversion Efficiency Enabled by Injection Vapor Deposition Technology
Authors: Duan Zhaoteng , Liang Xiaoyang , Feng Yang , Ma Haiya , Liang Baolai , Wang Ying , Luo Shiping , Wang Shufang , Schropp Ruud E. I. , Mai Yaohua , Li Zhiqiang
Published: June 2022

Binary Sb2Se3 semiconductors are promising as the absorber materials in inorganic chalcogenide compound photovoltaics due to their attractive anisotropic optoelectronic properties. However, Sb2Se3 solar cells suffer from complex and unconventional intrinsic defects due to the low symmetry of the quasi‐1D crystal structure resulting in a considerable voltage deficit, which limits the ultimate power conversion efficiency (PCE). In this work, the creation of compact Sb2Se3 films with strong [00l] orientation, high crystallinity, minimal deep level defect density, fewer trap states, and low non‐radiative recombination loss by injection vapor deposition is reported. This deposition technique enables superior films compared with close‐spaced sublimation and coevaporation technologies. The resulting Sb2Se3 thin‐film solar cells yield a PCE of 10.12%, owing to the suppressed carrier recombination and excellent carrier transport and extraction. This method thus opens a new and effective avenue for the fabrication of high‐quality Sb2Se3 and other high‐quality chalcogenide semiconductors.
Stimuli‐Responsive Hybrid Vesicle for Tumor Dual‐Model NIR‐II Photoacoustic and Fluorescence Imaging and Precise Radiotherapy
Authors: Lv Ningning , Zhang Xuan , Wang Shuhan , Wu Ying , Ge Xiaoguang , Song Jibin , Ma Qingjie , Gao Shi
Published: June 2022

Bioimaging guided‐radiotherapy is widely investigated as one of the mainstream cancer theranostic strategies for precision medicine. Nevertheless, background noise with “always‐on” imaging signal and inadequate tumor enrichment restrict disease diagnosis and therapy. Here, a nanogapped gold nanoparticles (AuNNPs)–silver sulfide (Ag2S) vesicle (Ve) is designed as a “biological switch” through the self‐assembly of pH‐responsive polymer thiolated polystyrene‐co‐poly(4‐vinylpyridine) grafted AuNNPs and Ag2S quantum dots (QDs). The AuNNPs–Ag2S Ve exhibits quenched NIR‐II fluorescence (FL) and enhanced photoacoustic signals initially, which can be specifically activated by an acidic environment to release Ag2S QDs and “turn on” NIR‐II FL signal in the second near‐infrared (NIR‐II, 950–1700 nm) window. Besides, the strategy of disease‐located NIR‐II imaging guided cancer therapy can remarkably enhance the therapeutic efficacy of radiotherapy, as well as minimize side effects. Such an intelligent nanoplatform with the ability of stimulus activated NIR‐II imaging guided radiotherapy shows great promise to precision biomedicine in the future.
Heterogeneous Catalysis for Carbon Dioxide Mediated Hydrogen Storage Technology Based on Formic Acid
Authors: Liu Mingxu , Xu Yuankang , Meng Yu , Wang Lijiao , Wang Hang , Huang Yichao , Onishi Naoya , Wang Lin , Fan Zhuangjun , Himeda Yuichiro
Published: June 2022

In the context of global carbon dioxide increasing drastically, renewable energy is crucial maintain the economic growth of the world. Hydrogen has attracted considerable attention as a clean fuel, but the large‐scale storage and controllable release of H2 is still urgently needed, yet largely not yet accomplished. Through the reactions of CO2 hydrogenation to formic acid (FA) and FA dehydrogenation to hydrogen, a “carbon neutral” sustainable hydrogen storage system can be constructed. With advantages of excellent recyclability and facile separation for heterogeneous catalysis, developing efficient heterogeneous catalysts for hydrogen storage based on FA is the primary focus of this review, mainly involving metal catalysts from nanoscale to single‐atom scale. Firstly, the effects of metal size on the catalytic activities are highlighted in detail. Additionally, special attention is paid to the relevant structure–activity relationships of various supported catalysts and the mechanistic insights, which can provide a theoretical foundation for rational catalyst design. This review brings new and systemic insights into innovative and efficient heterogeneous catalysts design and applications for the ultimate FA‐based sustainable hydrogen storage system with a closed carbon loop.
A versatile AIE fluorogen with selective reactivity to primary amines for monitoring amination, protein labeling, and mitochondrial staining
Authors: He Xinyuan , Xie Huilin , Hu Lianrui , Liu Pengchao , Xu Changhuo , He Wei , Du Wutong , Zhang Siwei , Xing Hao , Liu Xinyue , Park Hojeong , Cheung Tsz Shing , Li Min‐Hui , Kwok Ryan T. K. , Lam Jacky W. Y. , Lu Jian , Tang Ben Zhong
Published: June 2022

Specific bioconjugation for native primary amines is highly valuable for both chemistry and biomedical research. Despite all the efforts, scientists lack a proper strategy to achieve high selectivity for primary amines, not to mention the requirement of fast response in real applications. Herein, we report a chromone‐based aggregation‐induced emission (AIE) fluorogen called CMVMN as a self‐reporting bioconjugation reagent for selective primary amine identification, and its applications for monitoring bioprocesses of amination and protein labeling. CMVMN is AIE‐active and capable of solid‐state sensing. Thus, its electrospun films are manufactured for visualization of amine diffusion and leakage process. CMVMN also shows good biocompatibility and potential mitochondria‐staining ability, which provides new insight for organelle‐staining probe design. Combined with its facile synthesis and good reversibility, CMVMN would not only show wide potential applications in biology, but also offer new possibilities for molecular engineering.
Characteristics of suicide among farmers and ranchers: Using the CDC NVDRS 2003–2018
Authors: Miller Cristina D. M. , Rudolphi Josie M.
Published: June 2022

Background

Suicide is among the top 10 causes of premature death in the United States. This study provides details on farmer and rancher suicide decedents, including demographic information, mental health status, history of suicidal thoughts and attempts, and circumstances associated with death.

Methods

Data for this study were obtained from the Centers for Disease Control and Prevention's National Violent Death Reporting System Restricted Access Database for the years 2003–2018. Descriptive statistics and adjusted odds ratios are presented for farm and nonfarm populations in addition to farm populations by age groups and sex.

Results

This study found that almost half of the farmer suicide decedents were over 65 years old. Firearms were the most widely used method for farmers and ranchers regardless of age and sex. Young farmers and ranchers that died by suicide were more likely to have had relationship problems and older farmers and ranchers that died by suicides were more likely to have had a physical health problem. Male farmer and rancher suicide decedents were more likely to die by firearm than females, and female farmer and rancher suicide decedents were likely to have resided in a small metropolitan area, however, due to small numbers and suppression in the data, most sex comparisons were not able to be presented.

Conclusions

While no clear risk factor for suicide among farmers and ranchers emerged, results underscore the complex nature of suicide and the need for multifaceted, culturally competent interventions and campaigns that address suicide risk and prevention at the individual and community levels.
Relaxation of the Plant Cell Wall Barrier via Zwitterionic Liquid Pretreatment for Micelle‐Complex‐Mediated DNA Delivery to Specific Plant Organelles
Authors: Miyamoto Takaaki , Tsuchiya Kousuke , Toyooka Kiminori , Goto Yumi , Tateishi Ayaka , Numata Keiji
Published: June 2022

Targeted delivery of genes to specific plant organelles is a key challenge for fundamental plant science, plant bioengineering, and agronomic applications. Nanoscale carriers have attracted interest as a promising tool for organelle‐targeted DNA delivery in plants. However, nanocarrier‐mediated DNA delivery in plants is severely hampered by the barrier of the plant cell wall, resulting in insufficient delivery efficiency. Herein, we propose a unique strategy that synergistically combines a cell wall‐loosening zwitterionic liquid (ZIL) with a peptide‐displaying micelle complex for organelle‐specific DNA delivery in plants. We demonstrated that ZIL pretreatment can enhance cell wall permeability without cytotoxicity, allowing micelle complexes to translocate across the cell wall and carry DNA cargo into specific plant organelles, such as nuclei and chloroplasts, with significantly augmented efficiency. Our work offers a novel concept to overcome the plant cell wall barrier for nanocarrier‐mediated cargo delivery to specific organelles in living plants.
Site‐Selective Functionalization of Carboranes at the Electron‐Rich Boron Vertex: Photocatalytic B−C Coupling via a Carboranyl Cage Radical
Authors: Chen Meng , Xu Jingkai , Zhao Deshi , Sun Fangxiang , Tian Songlin , Tu Deshuang , Lu Changsheng , Yan Hong
Published: June 2022

Functionalization of carboranes in a vertex‐specific manner is a perennial challenge. Here, we report a photocatalytic B−C coupling for the selective functionalization of carboranes at the boron site which is most distal to carbon. This reaction was achieved by the photo‐induced decarboxylation of carborane carboxylic acids to generate boron vertex‐centered carboranyl radicals. Theoretical calculations also demonstrate that the reaction more easily occurs at the boron site bearing higher electron density owing to the lower energy barrier for a single‐electron transfer to generate a carboranyl radical. By using this strategy, a number of functionalized carboranes could be accessed through alkylation, alkenylation, and heteroarylation under mild conditions. Moreover, both a highly efficient blue emitter with a solid‐state luminous efficiency of 42 % and a drug candidate for boron neutron capture therapy (BNCT) containing targeting and fluorine units were obtained.
Microplastics and their Additives in the Indoor Environment
Authors: Salthammer Tunga
Published: June 2022

Analyses of air and house dust have shown that pollution of the indoor environment with microplastics could pose a fundamental hygienic problem. Indoor microplastics can result from abrasion, microplastic beads are frequently added to household products and microplastic granules can be found in artificial turf for sports activities and in synthetic admixtures in equestrian hall litter. In this context, the question arose as to what extent particulate emissions of thermoplastic materials from 3D printing should be at least partially classified as microplastics or nanoplastics. The discussion about textiles as a possible source of indoor microplastics has also been intensified. This Minireview gives an overview of the current exposure of residents to microplastics. Trends can be identified from the results and preventive measures can be derived if necessary. It is recommended that microplastics and their additives be given greater consideration in indoor environmental surveys in the future.
Origin of Red‐Shifted Phosphorescence from Triphenylamines: Triplet Excimer or Impurity?
Authors: Cheng Aoyuan , Jiang Yifan , Su Hao , Zhang Baicheng , Jiang Jun , Wang Tao , Luo Yi , Zhang Guoqing
Published: June 2022

Triphenylamine (TPA) was reported to exhibit temperature‐dependent dual phosphorescence, where the red‐shifted band was assigned as the excimeric phosphorescence with an energy shift of >3000 cm−1(J. Phys. Chem.1991,95, 7189). Here we show that purified TPA (purity: >99.97 %) shows a single phosphorescence band with a small energy shift of <200 cm−1under the same experimental conditions. The new experimental results, along with theoretical calculations, suggest that the previously reported triplet excimer of TPA is probably not valid and is most likely due to an unidentified impurity. As‐received TPA samples, however, do exhibit temperature‐dependent dual phosphorescence bands, and the wavelength, relative intensity, and temperature dependence of the lower‐energy phosphorescence band vary significantly depending on dopant structures. It was found that dopant phosphorescence could still become dominant even in dilute third‐party solutions of the host at low temperature.
Aufgabenspezifische Janus‐Materialien in der heterogenen Katalyse
Authors: Vafaeezadeh Majid , Thiel Werner R.
Published: June 2022

Janus‐Materialien sind anisotrope Nano‐ und Mikroarchitekturen, die zwei verschiedene Seiten mit unterschiedlichen oder entgegengesetzten physikochemischen Eigenschaften aufweisen. Parallel zur Entwicklung neuer Methoden zur Herstellung dieser Materialien wurden entscheidende Fortschritte in Bezug auf Anwendungen erzielt, z. B. in der Biologie, der Katalyse, der Pharmazie und neuerdings auch in der Batterietechnologie. Dieser Kurzaufsatz stellt die jüngsten und wichtigsten Erfolge bei der Anwendung aufgabenspezifisch funktionalisierter Janus‐Nanomaterialien im Bereich der heterogenen Katalyse für unterschiedliche chemische Transformationen vor. Er umfasst Reduktionreaktionen, oxidative Entschwefelung und Farbstoffabbau, asymmetrische Katalyse, Biomassetransformationen, Kaskadenreaktionen, Oxidationsreaktionen, übergangsmetallkatalysierte Kreuzkupplungsreaktionen, elektro‐ und photokatalytische Reaktionen sowie Gasphasenreaktionen. Zum Abschluss folgt ein Ausblick auf mögliche zukünftige Anwendungen.
Counter Electrode Reactions—Important Stumbling Blocks on the Way to a Working Electro‐organic Synthesis
Authors: Klein Martin , Waldvogel Siegfried R.
Published: June 2022

Over the past two decades, electro‐organic synthesis has gained significant interest, both in technical and academic research as well as in terms of applications. The omission of stoichiometric oxidizers or reducing agents enables a more sustainable route for redox reactions in organic chemistry. Even if it is well‐known that every electrochemical oxidation is only viable with an associated reduction reaction and vice versa, the relevance of the counter reaction is often less addressed. In this Review, the importance of the corresponding counter reaction in electro‐organic synthesis is highlighted and how it can affect the performance and selectivity of the electrolytic conversion. A selection of common strategies and unique concepts to tackle this issue are surveyed to provide a guide to select appropriate counter reactions for electro‐organic synthesis.
Water‐Soluble Melanin–Protein–Fe/Cu Conjugates Derived from Norepinephrine as Reliable Models for Neuromelanin of Human Brain Locus Coeruleus
Authors: Capucciati Andrea , Monzani Enrico , Sturini Michela , Nicolis Stefania , Zucca Fabio A. , Bubacco Luigi , Bortolus Marco , Zecca Luigi , Casella Luigi
Published: June 2022

Water‐soluble melanin‐protein‐Fe/Cu conjugates derived from norepinephrine and fibrillar β‐lactoglobulin are reliable models for neuromelanin (NM) of human brain locus coeruleus. Both iron and copper promote catecholamine oxidation and exhibit strong tendency to remain coupled in oligonuclear aggregates. The Fe‐Cu clusters are EPR silent and affect the 1H NMR spectra of the conjugates through a specific sequence of signals. Derivatives containing only Fe or Cu exhibit different NMR patterns. The EPR spectra show weak signals of paramagnetic FeIII in conjugates containing Fe or mixed Fe‐Cu sites due to small amounts of mononuclear centers. The latter derivatives exhibit EPR signals for isolated CuII centers. These features parallel the EPR behavior of NM from locus coeruleus. The spectral data indicate that FeIII is bound to the melanic fraction, whereas CuII is bound on the protein fibrils, suggesting that the Fe‐Cu clusters occur at the interface between the two components of the synthetic NMs.
1,5‐Allyl Shift by a Sequential Achmatowicz/Oxonia‐Cope/Retro‐Achmatowicz Rearrangement
Authors: Zhang Xiayan , Tong Yi , Li Gang , Zhao Hao , Chen Guanye , Yao Hongliang , Tong Rongbiao
Published: June 2022

1,3‐Allyl and 1,2‐allyl shifts through [3,3]‐ and [2,3]‐sigmatropic rearrangements are well‐established and widely used in organic synthesis. In contrast, 1,5‐allyl shift through related [3,5]‐sigmatropic rearrangement is unknown because [3,5]‐sigmatropic rearrangement is thermally Woodward–Hoffmann forbidden. Herein, we report an unexpected discovery of a formal 1,5‐allyl shift of allyl furfuryl alcohol through a 2‐step sequential rearrangement. Mechanistically, this formal 1,5‐allyl shift is achieved through a sequential ring expansion/contraction rearrangement: 1) Achmatowicz rearrangement (ring expansion), and 2) cascade oxonia‐Cope rearrangement/retro‐Achmatowicz rearrangement (ring contraction). This new 1,5‐allyl shift method is demonstrated with >20 examples and expected to find applications in organic synthesis and materials chemistry.
Controlling the Valence‐Electron Arrangement of Nickel Active Centers for Efficient Hydrogen Oxidation Electrocatalysis
Authors: Zhao Xu , Li Xiangyang , An Lulu , Zheng Lirong , Yang Jinlong , Wang Deli
Published: June 2022

The valence‐electron arrangement of heterogeneous catalysts can significantly affect the binding behavior of absorbates. However, it remains a challenge to understand the role of the valence‐electron arrangement in electrocatalysis, which limits its utilization as a tool to design efficient electrocatalysts. Here, we describe experiments in which the valence‐electron arrangement of Ni active centers for hydrogen oxidation is controlled precisely by using Ni‐vacancy‐enriched Ni3N as a platform. These Ni vacancies can promote the valence‐electron delocalization of OH‐adsorption centers to enhance the Ni ds–O 2p valence‐electron‐orbital interaction with elevated OH adsorption. Meanwhile, the deficit of valence‐electrons of H‐adsorption centers at Ni vacancies can lower Ni ds–H 1s interaction with weakened H binding. Relative to Ni3N poor in vacancies, the Ni‐vacancy‐enriched Ni3N showed a mass activity enhanced by 15‐fold. This strategy paves a rational way to design efficient catalysts by finely tuning the valence‐electron arrangement.
Total Synthesis and Prediction of Ulodione Natural Products Guided by DFT Calculations**
Authors: Bestwick Jacob S. , Jones David J. , Jones Helen E. , Kalomenopoulos Panagiotis G. , Szabla Rafal , Lawrence Andrew L.
Published: June 2022

A biomimetic synthetic strategy has resulted in a two‐step total synthesis of (±)‐ulodione A and the prediction of two potential natural products, (±)‐ulodiones C and D. This work was guided by computational investigations into the selectivity of a proposed biosynthetic Diels–Alder dimerization, which was then utilized in the chemical synthesis. This work highlights how biosynthetic considerations can both guide the design of efficient synthetic strategies and lead to the anticipation of new natural products.
Selective Oxidative Coupling of Methane to Ethylene in a Solid Oxide Electrolyser Based on Porous Single‐Crystalline CeO2 Monoliths
Authors: Ye Lingting , Shang Zhibo , Xie Kui
Published: June 2022

Catalytic conversion of CH4 to C2H4 plays an important role in the light olefin industry. Here, we report the electrochemical conversion of CH4 to C2H4/C2H6 at the anode with the electrolysis of CO2 to CO at the cathode in a solid oxide electrolyser. We constructed well‐defined interfaces that function as three‐phase boundaries by exsolving single‐crystalline Ni nanoparticles in porous single‐crystalline CeO2 monoliths. We engineered the chemical states and flux of active oxygen species for the oxidation of CH4 at the anode by controlling voltage and temperature. We show the unprecedented C2 selectivity (C2H4 and C2H6) of ≥99.5 % at a CH4 conversion of ≈7 %. The electrolyser exhibits excellent durability without performance degradation being observed in a continuous operation of 100 hours. Our work enables a novel path for the selective conversion of CH4/CO2 into useful chemicals, and the technique of building well‐defined interfaces may find potential applications in other fields.
Delineating the Bonghwang earth castle and Royal Palace of Geumgwan Gaya Kingdom using multiple geophysical techniques
Authors: Jeon Hang‐Tak , Hamm Se‐Yeong , Lee Hyoun‐Jae , Park Samgyu , Kim Sang‐Hyun
Published: June 2022

Geophysical techniques such as electrical resistivity, ground penetrating radar (GPR), gravity, magnetic, and seismic surveys are useful for prospecting archaeological remains. In this study, we delineated the domain and underground structure of the Bonghwang earth castle and the Royal Palace of the Geumgwan Gaya Kingdom, using multiple geophysical surveys (magnetic, electromagnetic, GPR, and electrical resistivity). Based on the results, the Bonghwang earth castle was extended from a small hill branching from the northern end of the Bonghwangdae hill with a width of 20 m to the hill on the southeast end with a width of slightly over 40 m. The Royal Palace inside the Bonghwang earth castle was further explored using magnetic and GPR surveys. As a result low magnetic values are surrounded radially by high magnetic values at multiple independent locations in an irregular shape in the centre of the Royal Palace. In contrast, the high anomaly zone near the centre of the Royal Palace had a rectangular or ellipsoidal shape, necessitating a clear need for archaeological investigation and excavation in the future.
Considerations for new manganese analytical techniques for drinking water quality management
Authors: Pei Yu , Prepas‐Strobeck Natasha S. , Payne Sarah Jane , She Zhe
Published: June 2022

Manganese (Mn) is a contaminant of emerging concern in drinking water, as recent epidemiologic evidence suggests an association between Mn exposure in drinking water and negative neurodevelopmental effects. The nature of Mn events in distribution systems can be sporadic and difficult to predict, with conventional laboratory methods being limited in their ability to provide the flexible on‐line Mn monitoring. Emerging methods such as colorimetric and electrochemical methods offer advantages for monitoring as they have potential to be less expensive, rapid, and readily deployed in the field. These emerging methods, however, face hurdles to adaptation and acceptance including demonstration of sufficient accuracy, precision, sensitivity and yet‐to‐be resolved issues with interfering agents. These hurdles are not insurmountable, and investment is warranted in these novel methods to address pressing needs by the water industry to protect human health. This review paper highlights the opportunities and advantages of advancing field‐testing techniques for Mn management.
Luminescent inorganic mixed borate phosphors materials for lighting
Authors: Tawalare Pritee Kishor
Published: June 2022

The need of new materials with desirable optical properties has become important in recent years. In particular, a need has emerged for compounds having better luminescence properties in various practical applications. The introduction of rare earth ions as activators improves the luminescence properties of the compounds considerably. Boron is one of the most abundant elements in nature. It readily combines with almost all other elements. In combination with oxygen; it forms borates comprised of various anions such as BO33−, B2O54−, etc. Apart from these simple borates, several complex compositions exist involving mixed anions as well as double metal borates, due to the three‐fold, or four‐fold coordination of borate atoms. Borates intrinsically possesses characteristics that are advantageous for optical materials, which include a wide transparency range, large electronic band gap, good thermal and chemical stability, low preparative temperature, optical stability with good nonlinear characteristics, and an exceptionally high optical damage threshold. The unique crystal structure of borates determines their enhanced ultraviolet light transparency, good nonlinearity, and relatively high resistance against laser‐induced damage. Some of these complex borates have interesting luminescence properties that are covered in this review. These include double borates containing rare earths RM3(BO3)4, pentaborates LaMgB5O10, M3R2(BO3)4, where M is an alkaline earth, mixed anion borates such as aluminoborate SrAl2B2O7, silicate‐borates such as pekovite, SrB2Si2O8, haloborates, M2B5O9X, where M is an alkaline earth and X is a halogen, phosphate borates, and MBPO5, where M is an alkaline earth. Phosphors based on these compositions find use in various applications such as fluorescence lamps, colour TVs, plasma display panels, high‐intensity discharge lamps based on xenon, optically pumped solid‐state lasers, eye‐safe lasers, and X‐ray imaging.
Comprehensively characterizing cellular changes and the expression of THSD7A and PLA2R1 under multiple in vitro models of podocyte injury
Authors: Zhang Rong , Shi Yu , Lu Yang , Wu Yuanyuan , Chen Miaomiao , Fan Yihui , Yuan Li , Mao Renfang
Published: June 2022

The unique morphology and gene expression of podocytes are critical for kidney function, and their abnormalities lead to nephropathies such as diabetic nephropathy and membranous nephropathy. Podocytes cultured in vitro are valuable tools to dissect the molecular mechanism of podocyte injury relative to nephropathy, however, these models have never been comprehensively compared. Here, we comprehensively compared the morphology, cytoskeleton, cell adhesion, cell spreading, cell migration, and lipid metabolism under five commonly used in vitro models including lipopolysaccharide (LPS), puromycin aminonucleoside (PAN), doxorubicin (Dox), high glucose, and glucose deprivation. Our results indicate that all stimulations significantly downregulate the expression of synaptopodin both in human and mouse podocytes. All stimulations affect podocyte morphology but show different intensity and phenotypes. In general, the five stimulations reduce cell adhesion, cell spreading, and cell migration, but the effect in human and mouse podocytes is slightly different. Human podocytes show high expression of genes enriched in the pentose phosphate pathway. Dox and PAN treatment show a strong effect on gene expression in lipid metabolism, while the other three stimulations show minimal effect. The expression of phospholipase A2 receptor (PLA2R1) and type‐1 domain‐containing protein 7 A (THSD7A) show opposite trends in given cells. Stimulations can dramatically affect the expression of PLA2R1 and THSD7A. Inhibition of super‐enhancers reduces PLA2R1 and THSD7A expression, but ERK inhibition enhances their expression. Our results demonstrate distinctive responses in five commonly used in vitro podocyte injury models and the dynamic expression of PLA2R1 and THSD7A, which supply novel information to select suitable podocyte injury models.