Longitudinal Field Research Articles

Preparation and electromagnetic wave absorption of compressible graphene aerogels

In this study, a developed easy-operation method was adopted to generate ultralight and compressible graphene aerogels by using graphene oxide and ammonia. By changing the process parameters, such as reduction temperature, reducing agent content and ammonia concentration, the variation laws of the density and pore size of aerogels were obtained, which aided in realizing the controllable preparation of aerogel structures. The prepared graphene aerogel has good compressive performance, and its density can reach 5.26 mg/cm3. Although it was repeatedly compressed 200 times under a load that was 4000 times as large as its own weight, it maintained its structural integrity and mechanical properties. An ideal model of three-dimensional graphene aerogel was constructed, and the electromagnetic wave absorption performance was simulated using the Computer Simulation Technology (CST) Microwave Studio software. The results showed that when the thickness, pore size and height of the sheet were 1.4, 5 and 14 mm, respectively, an optimal electromagnetic wave absorption effect of −31.08 dB could be obtained. Furthermore, the effects of thickness, pore size and height of the sheet on the electromagnetic wave absorption performance are revealed, which provide a reference for the structural design of aerogels with both compressibility and electromagnetic wave absorption performance.

Advanced Excitation Symmetry Analysis Method (ESAM) for improved automated ultrasonic testing of polished materials

One of the strategic plans of the international NDT community is to define standards for developing advanced and digitalized non-destructive testing for automated set-up in mass production [1,2]. Excitation Symmetry Analysis Method (ESAM) are new coded signal processing tools exploring symmetry properties [3]. ESAM method aims to extract the nonlinearity from an ultrasound output by studying the property of symmetry of the transfer function. More precisely, the extraction of nonlinearity is done using basis function associated to a group which is associated to an a priori transfer function. As soon as the linear tomography uses the invariant properties of amplitude dependence, nonlinear tomography should exploit the invariance properties (or symmetry properties) of the complex system. Consequently, the invariance of the stationary properties of a complex medium would be supposed to be associated to a signature of the degradation, that will be extracted with advanced signal processing tools. The idea remains the same: studying the symmetry and more precisely the time reversal one and the inversion. A signal processing is used to measure discrepancies in the autocorrelation function (output signal called chirp coda) for two inputs: a signal and its inversion (pulse inversion). The experiments were done on different sample with and without cracks. It has been shown that when the nonlinearities are extracted from the chirp coda amplitude are non- negligible in crack area and nonlinearities are out of phase. Then, mixing symmetries like time reversal and pulse inversion enable the detection of defect that are difficult to detect with conventional ultrasound method. Indeed, for such crack a destructive mechanical analysis called Jomini is done where the material is polished and examined with microscope. The sensitivity improvement of chirp-coded signal processing has been validated in various domains. Coded excitation techniques, used in communication systems such as radar and sonar provide improved SNR without increasing the amplitude of excitation. The typical test equipment consists of a preamplifier Juvitek TRA-02 (0.02 - 5 MHz) connected to a computer, an amplifier ENI model A150 (55 dB at 0.3-35 MHz), a shear wave transducer Technisonic (2.25 MHz), and a longitudinal wave transducer Panametrics V155 (5 MHz). The experimental device was tested with the V3 calibration block, improved, and specially scaled in order to access to a wide range of multivalued parameters: mechanical properties, ultrasonic parameters (celerity and attenuation) and local geometric data.

Quantitative analysis of laser-generated ultrasonic wave characteristics and their correlation with grain size in polycrystalline materials

Abstract The quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was evaluated. The high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation regime. An optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise ratio. An approach for characterizing grain size was proposed using spectral center frequency ratio (SCFR) based on time-frequency analysis. The results have demonstrated that the generation regime of ultrasonic waves is not solely determined by the laser power density; even at high power densities, a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic effect. It is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power density. Furthermore, both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials; however, the shear wave SCFR is more sensitive to finer-grained materials. This study holds great significance for evaluating metal material properties using laser ultrasound.

Modeling of Acoustic Coupling of Ultrasonic Probes for High-Speed Rail Track Inspection

The paper presents the modeling of transmission of the ultrasonic plane wave through an uniform liquid layer. The considered sources of the ultrasonic wave were normal (straight) beam longitudinal wave probes and angle beam sheer waves probes commonly used in non-destructive testing. Coupling losses (CL) introduced by the presence of the coupling layer are discussed and determined applying the numerical procedure. The modeling applies to both monochromatic waves and short ultrasonic pulses with a specified frequency bandwidth. Model implementation and validation was performed using a specialized software. The predictions of the model were confirmed by coupling losses measurements for a normal beam longitudinal wave probe with a delay line made of polymethyl methacrylate (PMMA). The developed model can be useful in designing ultrasonic probes for high-speed rail track inspections, especially for establishing the optimal thickness of the water coupling layer and estimation of coupling losses, due to inevitable changes of the water gap during mobile rail inspection.

Detecting heart failure from B-mode ultrasound characterisation of arterial pulse waves.

This study investigated the sensitivity and specificity of identifying heart failure with reduced ejection fraction (HFrEF) from measurements of the intensity and timing of arterial pulse waves. Previously validated methods combining ultrafast B-mode ultrasound, plane-wave transmission, singular value decomposition and speckle tracking were used to characterise the compression and decompression ("S" and "D") waves occurring in early and late systole, respectively, in carotid arteries of outpatients with left ventricular ejection fraction (LVEF) <40%, determined by echocardiography, and signs and symptoms of heart failure, or with LVEF ≥50% and no signs or symptoms of heart failure. On average, the HFrEF group had significantly reduced S-wave intensity and energy, a greater interval between the R wave of the ECG and the S wave, a reduced interval between the S and D waves, and an increase in the S-wave shift, a novel metric that characterises the shift in timing of the S-wave away from the R wave of the ECG and towards the D wave (all p<0.01). Receiver operating characteristics (ROCs) were used to quantify for the first time how well wave metrics classified individual participants. S-wave intensity and energy gave areas under the ROC of 0.76-0.83, the ECG- S wave interval gave 0.85-0.88, and the S-wave shift gave 0.88-0.92. Hence the methods, which are simple to use and do not require complex interpretation, provide sensitive and specific identification of HFrEF. If similar results were obtained in primary care, they could form the basis of techniques for heart failure screening.

Reflection, transmission and AVO response of inhomogeneous plane waves in thermoporoelastic media with two-temperature equations of heat conduction

We develop a modified fluid-saturated thermoporoelastic model by introducing two temperature equations to account for the temperature differences between the solid skeleton and the pore filling. The modified two-temperature-generalized thermoporoelastic (TTG) equation is an extension of the classical single-temperature (ST) Lord-Shulman (LS), Green-Lindsay (GL) and generalized LS theories. It predicts four compressional waves and one shear wave based on the analysis of inhomogeneous plane waves. We study the exact reflection and transmission coefficients (R/T) at the interface separating two thermoporoelastic half-spaces and develop an amplitude-variation-with-offset (AVO) approximation. Comparison with the Biot poroelastic case of the water/oil contact shows that the TTG model reproduces the exact R/T results. The AVO response of oil, gas, and real CO2 geosequestration reservoirs illustrates the practical applicability of the proposed model and provides the theoretical basis for the exploration of high-temperature resources.

Depth imaging of multicomponent seismic data through the application of 2D full‐waveform inversion to P‐ and SH‐wave data: SEAM II Barrett model study

AbstractWe examine the value of the nine‐component seismic survey by generating the Kirchhoff depth migration images of compressional wave (P‐wave), converted wave (PS‐wave) and horizontally polarized shear wave (SH shear wave) data simulated from the SEAM II Barrett unconventional model. We first utilize full waveform inversion to obtain a P‐wave velocity model from P‐wave data and an S‐wave velocity model from SH‐wave data. Both P‐wave and SH‐wave data are generated with the maximum frequency of 20 Hz while assuming that the subsurface is isotropic. To implement full waveform inversion, we use a two‐dimensional time‐domain finite‐difference method and the L2 norm to measure the data misfit. We use both refractions and reflections in P‐ and SH‐wave data to reconstruct the P‐ and S‐wave velocity models from the surface to the reservoir. The inverted P‐ and S‐wave velocities contain the main features of the model (e.g., major faults and channels) but have some difficulties in estimating high‐frequency velocity variation within the first 300‐m depth of the model due to the frequency constraint. We then use the inverted P‐ and S‐wave velocities to generate Kirchhoff depth migration gathers and images from the P‐, PS‐ and SH‐wave data. The flat P‐ and SH‐wave common‐image offset gathers suggest that SH‐ and P‐wave full waveform inversion can generate adequate S‐ and P‐wave velocities for migration. Flat PS‐wave gathers and the clear PS‐wave migration image are also obtained using the inverted P‐ and S‐wave velocities simultaneously. This result indicates that obtaining S‐wave velocities from SH‐wave data can aid PS‐wave data processing and imaging. Moreover, the SH‐wave images and S‐wave images of the radial component provide better delineation of fault planes and small‐scale geobodies within the reservoir since the wavelength of the S‐wave is smaller compared to P‐wave when similar frequency ranges are recorded. Therefore, our study shows that S‐wave velocities can be successfully constructed by the two‐dimensional full waveform inversion application of the SH‐wave data. The subsequent imaging of multicomponent seismic data improves the delineation of certain unconventional reservoirs compared to the traditional P‐wave imaging.

Study on Ultrasonic Characteristics and Prediction of Rock with Different Pore Sizes

The internal defects of rocks are the main cause of instability and failure in underground engineering. Therefore, using ultrasonic monitoring technology to study the defect characteristics of rocks containing voids is of great significance. The research results indicate that with the increase in the pore size, the longitudinal wave velocity and first wave amplitude of rocks containing voids decrease, the attenuation coefficient increases, and the difference in ultrasonic parameters between rocks containing voids and intact rocks increases, resulting in a significant decrease in the rock integrity. The propagation of ultrasonic waves in porous rocks can be divided into three stages, where obvious ultrasonic reflection, diffraction, and scattering occur. The attenuation of sound pressure is significant, and the ultrasonic sound pressure is negatively linearly correlated with the pore size. Based on the amplitude, velocity, and pressure of ultrasonic waves, an ANN-based method for predicting the pore size of rocks is proposed, which inverts and predicts the pore size of rock masses with high prediction accuracy.

Candidates for downstream jets at interplanetary shocks

Abstract Localised dynamic pressure enhancements arising from kinetic processes are frequently observed downstream of the Earth’s bow shock. These structures, called jets, modify their plasma surroundings and participate in particle energisation. Here, we report the first observations of jet-like structures at a non-planetary shock environment: downstream of interplanetary shocks. We introduce an analysis approach suitable for such conditions and apply it to Wind spacecraft data. We present one event with a Mach number similar to the Earth’s bow shock as a benchmark, as well as two low Mach number, low beta shocks: a parameter range that is difficult to access at planets. The jet-like structures we find are tens of ion inertial lengths in size, and some are observed further away from the shock than in a limited magnetosheath. We find that their properties are similar to those of magnetosheath jets: in the frame of the shock these structures are fast, cold, and most have no strong magnetic field variations. All three interplanetary shocks feature foreshock activity, but no strongly compressive waves. We discuss the implications these findings have for the proposed jet formation mechanisms.

Ultrasound Elastography: Methods, Clinical Applications, and Limitations: A Review Article

Ultrasound is a highly adaptable medical imaging modality that offers several applications and a wide range of uses, both for diagnostic and therapeutic purposes. The principles of sound wave propagation and reflection enable ultrasound imaging to function as a highly secure modality. This technique facilitates the production of real-time visual representations, thereby assisting in the evaluation of various medical conditions such as cardiac, gynecologic, and abdominal diseases, among others. The ultrasound modality encompasses a diverse range of modes and mechanisms that serve to enhance the methodology of pathology and physiology assessment. Doppler imaging and US elastography, in particular, are two such techniques that contribute to this expansion. Elastography-based imaging methods have attracted significant interest in recent years for the non-invasive evaluation of tissue mechanical characteristics. These techniques utilize the changes in soft tissue elasticity in various diseases to generate both qualitative and quantitative data for diagnostic purposes. Specialized imaging techniques collect data by identifying tissue stiffness under mechanical forces such as compression or shear waves. However, in this review paper, we provide a comprehensive examination of the fundamental concepts, underlying physics, and limitations associated with ultrasound elastography. Additionally, we present a concise overview of its present-day clinical utilization and ongoing advancements across many clinical domains.

Micro-jetting and Transverse Waves in Oblique Detonations

We present a highly-resolved 2D numerical simulation of a wedge-induced Oblique Detonation Wave (ODW) using a 9-species 21-reaction chemical kinetic mechanism for a stoichiometric H2-air mixture. Adaptive Mesh Refinement (AMR) is leveraged to obtain a resolution close to the continuum limit at the finest level (Δxfinest=0.78μm=20λ, where λ is the mean-free path of the fuel–air mixture), which spans the ODW front and its transverse waves. The simulation is performed for a sufficiently large domain, enabling us to unveil the multi-zonal structure of the ODW. We capture, for the first time, the onset of microscopic hypersonic jets (micro-jets) far downstream of the wedge tip associated with cellular structures resembling those of a multi-headed Normal Detonation Wave (NDW). In contrast, the upstream “cell-like” structure (christened as “pseudo-cellular” hence) are found to be devoid of these micro-jets with a morphology similar to that of single-headed NDWs, such as spinning/zig-zag detonations in tubes/2D channels, respectively. A detailed investigation into the transverse-shock structure downstream reveals that a colliding pair of transverse waves lead to the micro-jetting phenomenon. The absence of one of the pair of transverse waves in the upstream region results in the observed pseudo-cellular structures. The origin of these transverse waves in an ODW, unclear in previous literature, is shown to arise from coalescing and strengthening of Compression Waves (CWs) that are produced from two distinct mechanisms. During the “early” phase of the ODW stabilization, CWs are formed as a result of local blast events. In the subsequent “middle” phase, these are formed as a result of the shear-layer instabilities coupling with the local shock structure, leading to the so-called left-running transverse waves (LRTWs) upstream and the right-running transverse waves (RRTWs) downstream. The identified mechanisms offer a plausible explanation on why ODWs exhibit a multi-zonal morphology.Novelty and Significance StatementThe present study is one of the very few studies in the Oblique Detonation Wave (ODW) literature that includes multi-step chemistry while solving for the compressible reacting Navier-Stokes equations on a large simulation domain revealing the multi-zonal structure of the ODW. Furthermore, the resolution employed for the study approaches the continuum limit, making it on-par with the current state-of-the-art for ODW simulation. For the first time, this study has demonstrated the existence of microscopic hypersonic jets (micro-jets) far downstream of the wedge tip in a wedge-induced ODW and a method to isolate them in numerical simulations, leading to insights on the broader micro-jetting phenomenon in detonations. The existence of a cell-like (which we term as “pseudo-cellular”) region bearing similarity with that of single-headed spinning detonations is also noted due to the absence of a transverse wave family upstream. The exact physical mechanisms leading to the formation of transverse waves in ODW are also investigated, which were previously ambiguous in the literature.

Prediction of tight sandstone reservoirs by multi-wave joint prestack inversion technology: A case study of QL area in Sichuan Basin

The Shaximiao (SXM) Formation of the Middle Triassic in central Sichuan basin is a river-lake sedimentary system, with an average burial depth of 2800 m. The channel sand bodies of SXM Formation in QL area are developed with large lateral variation and high- and medium- porosity sand. This leads to great difference in seismic response, and difficulty in predicting sand bodies and reservoirs using compressional wave (P-wave) data. We carried out well log analysis for different types of sand bodies. No. 8 sand body of high porosity can be effectively identified by P-wave impedance ( PI). Whereas for No. 7 sand body of relatively lower porosity (mainly due to the higher shale content in the 7 No. 7 sand compared to No. 8 sand), sandstone and mudstone can be distinguished by using shear wave (S-wave) impedance ( SI), and reservoirs can be recognized by P-wave to S-wave velocity ratio ( V p /V s). Based on PP-wave and P-to-S converted wave (PS-wave) (after matching) angle stacked data, prestack inversion of multicomponent data is performed. Multiwave joint inversion results ( SI and V p /V s) have better accuracy and stronger stability than PP-wave inversion in practical application. Besides, the PI of joint inversion more clearly describes the distribution and boundaries of channel sand, and better matches the prediction and drilling data in Sand 8. The SI of joint inversion can identify subtle sand bodies (weak PI contrast) that are difficult to be detected by PP-wave inversion. The distribution of reservoir predicted by V p /V s of joint inversion are clearer (No. 7 sand body) and better than that by PP-wave inversion. This study demonstrates the advantage of the multiwave joint inversion technology in tight sand identification.

Damage prediction and improvement method based on cutting mode of circular empty hole

Based on the theory of empty hole effect of cutting blasting, the Hopkinson effect and Saint–Venant principle are integrated to establish a two-dimensional calculation model of dynamic stress evolution of the holes wall, and then the dynamic fracture mechanism and damage distribution mode of the rock mass in the cutting area under the action of longitudinal waves are predicted. The results of the calculation and numerical simulation are verified by experiments, and the results show that: The time-varying stress function of the circular cavity wall conforms to the periodic dynamic evolution of the trigonometric function, and the theoretical calculation is consistent with the simulation results. Through the calculation of the round holes cut model and the square empty hole cut model, the change of the shape of the holes in the cut area changes the failure form of the surrounding rock mass. The circular empty hole wall is affected by the stress wave to produce "interval ring" destruction, and the effect of the reflected stretch wave is inhibited. The large range of rock mass in the square empty hole wall produces tensile and shear failure, and the rock mass collapses inward under the influence of the second stage stress. Among them, the empty space utilization rate of the square empty hole model is about 8.5 times that of the circular holes model. Vibration monitoring in the center of the cutting area shows that the vibration effect of the circular empty hole is larger than that of the square empty hole, and the proportion of rock breaking energy is lower.

Determination of Earthquake Depths Using Data of Cross-Sectional and Areal Deep Seismic Studies in Siberia

Abstract ––Information on the distribution of earthquake hypocenters for many seismically active zones of Siberia remains insufficient, which is associated with sparse networks of seismological observations. The paper presents the results of determining the earthquake depths in several seismogenic areas in the Altai-Sayan region, Cisbaikalia, Transbaikalia, and Yakutia using the travel time of longitudinal refracted waves from the Mohorovičič discontinuity (Pn waves) from earthquakes and the recently obtained information about the deep structure of these regions. The depth determination algorithm is tested using data from aftershocks of large earthquakes occurring in Tuva in 2011 and 2012 (ML = 6.7 and 6.8), recorded both by the regional seismological network and by a local group of seismic stations. Different methods are applied to reveal that some aftershock depths have a close match, including those for the main shocks – the Tuva-1 and Tuva-2 earthquakes. Another good match of earthquake depths is obtained using Рn waves with materials from regional and detailed studies of the Baikal branch of the Geophysical Survey of the Russian Academy of Sciences in the Muyakan activation site in the Baikal rift zone. The resulting data complement the information on the hypocenter of the main shock and confirm the change of the Muyakan activation cluster from large depths to shallow ones since the onset of activation in 2014. New information on the earthquake depths using Рn waves is obtained in Yakutia along the border of the largest Eurasian and Okhotsk tectonic plates. It is revealed that they decrease to 6–12 km as compared to higher depths of 20–30 km in adjacent areas. The resulting series of new information on the distribution of earthquake hypocenters using Рn waves is extremely important mostly because it indicates the possibility of identifying and redefining earthquake hypocenters using previous seismological observations in seismically active zones of Siberia.

Muon spin relaxation and emergence of disorder induced unconventional dynamic magnetic fluctuations in Dy2Zr2O7.

The disordered pyrochlore oxide Dy2Zr2O7shows the signatures of field-induced spin freezing with remnant zero-point spin-ice entropy at 5 kOe magnetic field. We have performed zero-field and longitudinal field Muon spin relaxation (μSR) studies on Dy2Zr2O7. Our zero field studies reveal the absence of both long-range ordering and spin freezing down to 62 mK. The μSR relaxation rate exhibits a temperature-independent plateau below 4 K, indicating a dynamic ground state of fluctuating spins similar to the well-known spin ice system Dy2Ti2O7. The low-temperature spin fluctuations persist in the longitudinal field of 20 kOe as well and show unusual field dependence of the relaxation rate, which is uncommon for a spin-liquid system. Our results, combined with the previous studies do not show any evidence of spin ice or spin glass ground state, rather point to a disorder-induced dynamic magnetic ground state in the Dy2Zr2O7material.

Enhancing thermal stability of optimal magnetization reversal in nanoparticles

Energy-efficient switching of nanoscale magnets requires application of a time-varying magnetic field characterized by microwave frequency. At finite temperatures, even weak thermal fluctuations induce perturbations in the magnetization that can accumulate in time, disrupt the phase locking between the magnetization and the applied field, and eventually compromise magnetization switching. It is demonstrated here that the magnetization reversal is mostly disturbed by unstable perturbations arising in a certain domain of the configuration space of a nanomagnet. The instabilities can be suppressed and the probability of magnetization switching enhanced by applying an additional stimulus such as a weak longitudinal magnetic field that ensures bounded dynamics of the perturbations. Application of the stabilizing longitudinal field to a uniaxial nanomagnet makes it possible to reach a desired probability of magnetization switching even at elevated temperatures. The principle of suppressing instabilities provides a general approach to enhancing thermal stability of magnetization dynamics. Published by the American Physical Society 2024

Impact resistance behaviors of boride reinforced Ti-6Al-4 V functionally graded materials: Experimental and numerical analysis

The impact resistant behaviors of boride reinforced Ti-6Al-4 V functionally graded materials prepared by spark plasma sintering (SPS) with compositional gradients of 90°, 84°, 82°and 79° were investigated based on the experimental test and the finite element method. The material constitutive parameters of the boride reinforced Ti-6Al-4 V alloys with different TiB2 contents were determined, and the Johnson Holmquist Ceramics (JH-2) model and a cohesive contact model were established and developed to predict the crack propagation and the impact resistance behaviors of the materials. The calculated results agreed well with the split Hopkinson press bar (SHPB) experimental results. The optimum material composition gradient design scheme with a continuous transition property from a high-toughness end to a high-strength end along the thin-thickness direction was determined. The G84 (0, 0, 15, 30 wt% TiB2) had the best impact resistance, with Young's modulus of 55505±5 GPa, compressive strength of 2045±5 MPa, and microhardness ranging from 535±5HV to 1246±5HV, exhibiting high strength and hardness at a high-strength end that can prolong the interaction time between the impactor and the materials, while the elongation of 39 % at its high-toughness end can cause tensile deformation, consuming impact kinetic energy efficiently. Combined with the experimental and numerical analysis results, the impact resistance and the crack-alleviated mechanisms of boride reinforced Ti-6Al-4 V functionally graded materials were discussed. Reducing the compositional gradient can alleviate the difference in coefficients of thermal expansion between composites, which may lead to strengthen the reflected wave, lower the compression wave, and suppress high-strength end failure efficiently, meaning of relieving the stress concentration under extreme service conditions. Moreover, the effects of the presence of the borides, such as in situ-formed TiB, remained TiB2at al., the dislocation defects and the whisker-like TiB on the armour materials resist fracture and layer cracking were also analyzed. This work provided a method for designing high performance of boride reinforced Ti-6Al-4 V functionally graded materials with high impact resistance and thin thickness.

Detecting Drivers of Behavior at an Early Age: Evidence from a Longitudinal Field Experiment

Detecting Drivers of Behavior at an Early Age: Evidence from a Longitudinal Field Experiment

Promoting solidarity based collective action through increasing hope using nonviolent communication intervention

AbstractThe present study explores the impact of nonviolent communication (NVC) intervention on advantaged group members’ actual participation in collective action on behalf of disadvantaged outgroups, also known as solidarity‐based collective action (SBCA). It also examines the mediating role of hope and empathy in this process. Using an experimental longitudinal field study in the context of the Israeli–Palestinian conflict, Jewish Israelis (N = 220) were randomly assigned either to an NVC or to a control condition. Results indicated that, relative to the control, participants in the NVC condition showed an increased tendency to engage in activities that are considered part of SBCA 6 weeks after the intervention. Furthermore, the NVC intervention affected both hope and empathy by maintaining higher levels of hope 6 weeks after intervention and by increasing empathy immediately after intervention. Yet hope, but not empathy, mediated the effect of the NVC intervention on participation in SBCA. Theoretical and applicable implications are discussed.

Responsivity Surge in MAPbI3:PC61BM/Au/ZnO Sandwich‐Structured Photodetector

AbstractThe low gain in the presence of a single transverse external electric field limits the application of metal‐semiconductor‐metal (MSM) photodetectors. Here, a longitudinal built‐in electric field by spin‐coating CH3NH3PbI3:PC61BM on the electrode region of an Au/ZnO MSM photodetector, which constitutes a vertically crossed composite electric field with a transverse external electric field, is constructed. In this case, the transverse electric field collects the electrons, and the longitudinal electric field separates them. Based on this novel electric field structure, carrier multiplication at lower voltage conditions is achieved. Compared to the low voltage, there is a significant amplification effect when the voltage reaches 7 V. The responsivity is increased ≈270 times for UV–vis wavelengths, escalating from ≈0.02 to ≈5.4 A W−1. This study provides a novel carrier transport control scheme for high‐gain perovskite‐based photodetectors.