bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasound-induced lung hemorrhage: Role of acoustic boundary conditions at the pleural surface
Authors: O’Brien William D. , Kramer Jeffrey M. , Waldrop Tony G. , Frizzell Leon A. , Miller Rita J. , Blue James P. , Zachary James F.
Published: July 2002

In a previous study [J. Acoust. Soc. Am. 108, 1290 (2000)] the acoustic impedance difference between intercostal tissue and lung was evaluated as a possible explanation for the enhanced lung damage with increased hydrostatic pressure, but the hydrostatic-pressure-dependent impedance difference alone could not explain the enhanced occurrence of hemorrhage. In that study, it was hypothesized that the animal’s breathing pattern might be altered as a function of hydrostatic pressure, which in turn might affect the volume of air inspired and expired. The acoustic impedance difference between intercostal tissue and lung would be affected with altered lung inflation, thus altering the acoustic boundary conditions. In this study, 12 rats were exposed to 3 volumes of lung inflation (inflated: approximately tidal volume; half-deflated: half-tidal volume; deflated: lung volume at functional residual capacity), 6 rats at 8.6-MPa in situ peak rarefactional pressure (MI of 3.1) and 6 rats at 16-MPa in situ peak rarefactional pressure (MI of 5.8). Respiration was chemically inhibited and a ventilator was used to control lung volume and respiratory frequency. Superthreshold ultrasound exposures of the lungs were used (3.1-MHz, 1000-Hz PRF, 1.3-μs pulse duration, 10-s exposure duration) to produce lesions. Deflated lungs were more easily damaged than half-deflated lungs, and half-deflated lungs were more easily damaged than inflated lungs. In fact, there were no lesions observed in inflated lungs in any of the rats. The acoustic impedance difference between intercostal tissue and lung is much less for the deflated lung condition, suggesting that the extent of lung damage is related to the amount of acoustic energy that is propagated across the pleural surface boundary.
Rotational aerophones
Authors: Fletcher N. H. , Tarnopolsky A. Z. , Lai J. C. S.
Published: July 2002

Free rotational aerophones such as the bullroarer, which consists of a wooden slat whirled around on the end of a string, and which emits a loud pulsating roar, have been used in many ancient and traditional societies for ceremonial purposes. This article presents an experimental and theoretical investigation of this instrument. The aerodynamics of rotational behavior is elucidated, and relates slat rotation frequency to slat width and velocity through the air. Analysis shows that sound production is due to generation of an oscillating-rotating dipole across the slat, the role of the vortices shed by the slat being relatively minor. Apparent discrepancies between the behavior of a bullroarer slat and a slat mounted on an axle in a wind tunnel are shown to be due to viscous friction in the bearings of the wind-tunnel experiment.
Comparing Kirchhoff-approximation and boundary-element models for computing gadoid target strengths
Authors: Foote Kenneth G. , Francis David T. I.
Published: July 2002

To establish the validity of the boundary-element method (BEM) for modeling scattering by swimbladder-bearing fish, the BEM is exercised in several ways. In a computation of backscattering by a 50-mm-diam spherical void in sea water at the four frequencies 38.1, 49.6, 68.4, and 120.4 kHz, agreement with the analytical solution is excellent. In computations of target strength as a function of tilt angle for each of 15 surface-adapted gadoids for which the swimbladders were earlier mapped, BEM results are in close agreement with Kirchhoff-approximation-model results at each of the same four frequencies. When averaged with respect to various tilt angle distributions and combined by regression analysis, the two models yield similar results. Comparisons with corresponding values derived from measured target strength functions of the same 15 gadoid specimens are fair, especially for the tilt angle distribution with the greatest standard deviation, namely 16°.
Nonlinear elastic constants of solids with cracks
Authors: Nazarov Veniamin E. , Sutin Alexander M.
Published: July 2002

Experimental data on a cracked medium exhibiting high acoustic nonlinearity is a commonly observed phenomenon. Here a physical model of a medium with cracks is suggested to explain the observed phenomena. The model is based on the assumption of uniform stress that is valid for a low concentration of cracks. The crack behavior is described using the model in which a crack is represented as an elastic contact of two rough surfaces, pressed one to the other under the action of internal stresses in the surrounding solid. Linear and nonlinear acoustic constants of the fractured medium are calculated. It is shown that, in this medium, negative values of the Poisson’s ratio and anomalously high values of the nonlinear constants are possible.
Auditory models of formant frequency discrimination for isolated vowels
Authors: Kewley-Port Diane , Zheng Yijian
Published: July 2002

Thresholds for formant discrimination of female and male vowels are significantly elevated by two stimulus factors, increases in formant frequency and fundamental frequency [, J. Acoust. Soc. Am. 100, 2462–2470 (1996)]. The present analysis systematically examined whether auditory models of vowel sounds, including excitation patterns, specific loudness, and a Gammatone filterbank, could explain the effects of stimulus parameters on formant thresholds. The goal was to determine if an auditory metric could be specified that reduced variability observed in the thresholds to a single-valued function across four sets of female and male vowels. Based on -Port [J. Acoust. Soc. Am. 99, 3770–3781 (1996)], four critical bands around the test formant were selected to calculate a metric derived from excitation patterns. A metric derived from specific loudness difference (ΔSone) was calculated across the entire frequency region. Since analyses of spectra from Gammatone filters gave similar results to those derived from excitation patterns, only the 4-ERB (equivalent rectangular bandwidth) and ΔSone metrics were analyzed in detail. Three criteria were applied to the two auditory metrics to determine if they were single-valued functions relative to formant thresholds for female and male vowels. Both the 4-ERB and ΔSone metrics met the criteria of reduced slope, reduced effect of fundamental frequency, although ΔSone was superior to 4-ERB in reducing overall variability. Results suggest that the auditory system has an inherent nonlinear transformation in which differences in vowel discrimination thresholds are almost constant in the internal representation.
Importance of tonal envelope cues in Chinese speech recognition
Authors: Fu Qian-Jie , Zeng Fan-Gang , Shannon Robert V. , Soli Sigfrid D.
Published: July 2002

Recent studies have shown that temporal waveform envelope cues can provide significant information for English speech recognition. This study investigated the use of temporal envelope cues in a tonal language: Mandarin Chinese. In this study, the speech was divided into several frequency analysis bands; the amplitude envelope was extracted from each band by half-wave rectification and low-pass filtering and was used to modulate a noise of the same bandwidth as the analysis band. These manipulations preserved temporal and amplitude cues in each frequency band, but removed the spectral detail within each band. Chinese vowels, consonants, tones and sentences were identified by 12 native Chinese-speaking listeners with 1, 2, 3, and 4 noise bands. The results showed that the recognition score of vowels, consonants, and sentences increased monotonically with the number of bands, a pattern similar to that observed in English speech recognition. In contrast, tones were consistently recognized at about 80% correct level, independent of the number of bands. This high level of tone recognition produced a significant difference in the open-set sentence recognition between Chinese (11.0%) and English (2.9%) for the one-band condition where no spectral information was available. The data also revealed that, with primarily temporal cues, the falling–rising tone (tone 3) and the falling tone (tone 4) were more easily recognized than the flat tone (tone 1) and the rising tone (tone 2). This differential pattern in tone recognition resulted in a similar pattern in word recognition: words having either tone 3 or 4 were more likely to be recognized while words having tone 1 and 2 were not. The quantitative role of tones in Chinese speech recognition was further explored using a power-function model and found to play a significant role in relating phoneme recognition to sentence recognition.
Mandrel effects on the dipole flexural mode in a borehole
Authors: Hsu Chaur-Jian , Sinha Bikash K.
Published: July 2002

The flexural mode is the lowest-order borehole mode with dipole excitation. The low-frequency asymptote of the flexural wave speed is used to estimate the formation shear speed in well logging. The borehole flexural mode measurement system consists of a mandrel that holds the transmitter and an array of receivers. This mandrel is, generally, designed to minimize the interference between any mandrel and the borehole flexural modes. A slotted sleeve housing that makes the sleeve arrival significantly slower than the formation arrival enables the processing of the recorded waveforms based on a model of fluid-filled boreholes without any mandrel. The objective of this work is to investigate the basic physics of mandrel effects on borehole flexural mode for the condition that the mandrel is in the form of a rod or pipe that is not necessarily slower than the formation arrivals. To this end, we describe an experimental and theoretical study of flexural modes in a borehole with a concentric mandrel and water annulus. The mandrels are of simple geometry such as a rod or a pipe, not intended to model any particular sonic tool in its entirety. However, the presence of a rod or a pipe can approximately represent the waveguide nature of the mandrel and its possible influence on borehole flexural modes. A fluid-filled (without any tool) borehole and a mandrel immersed in an infinite fluid (without any borehole) are two independent systems. Each supports a flexural mode that can be excited by a dipole source. These two uncoupled modes have distinct velocity dispersions. In a coupled mandrel-in-borehole system, two flexural modes are generated with a dipole source. These two coupled modes may resemble or significantly differ from the two uncoupled modes depending on the proximity of dispersions of these two uncoupled modes.
Nonlinear pulse propagation in shallow-water environments with attenuating and dispersive sediments
Authors: Kulkarni Rahul S. , Siegmann William L. , Collins Michael D. , McDonald B. Edward
Published: July 2002

A hybrid treatment for wide-angle paraxial propagation that includes effects of both sediment dispersion and weak nonlinearity has been developed. A Fourier transform approach is used to combine effects of refraction, diffraction, and sediment dispersion in the frequency domain, and nonlinear effects in the time domain. A nonlinear wide-angle time-domain equation developed recently is first split into linear and nonlinear component equations. The linear equation is decomposed into its discrete frequency-domain counterparts. Sediment attenuation and dispersion are incorporated using a complex wave number along with a frequency-dependent formula for phase velocity to satisfy causality. The numerical implementation consists of first decomposing a broadband source into its frequency components and propagating them over a range step using a wide-angle parabolic equation. Fourier synthesis is used to reconstruct the signal which is then corrected to account for nonlinear effects in the time domain. Numerical examples illustrating the effects of dispersion and nonlinearity on shallow-water wide-angle propagation are presented and compared with available results.
A speech corpus for multitalker communications research
Authors: Bolia Robert S. , Nelson W. Todd , Ericson Mark A. , Simpson Brian D.
Published: July 2002

A database of speech samples from eight different talkers has been collected for use in multitalker communications research. Descriptions of the nature of the corpus, the data collection methodology, and the means for obtaining copies of the database are presented.
Experience with a yes–no single-interval maximum-likelihood procedure
Authors: Leek Marjorie R. , Dubno Judy R. , He Ning-ji , Ahlstrom Jayne B.
Published: July 2002

The report in 1993 by Green [J. Acoust. Soc. Am. 93, 2096–2105 (1993)] describing the application of a new psychophysical method requiring few trials and little time to measure auditory thresholds has generated considerable interest among experimentalists. The procedure uses a single-interval stimulus presentation, requests a yes–no decision by subjects, and implements a maximum-likelihood calculation to determine the next trial stimulus level within an adaptive track, as well as the final threshold estimate. Data are presented here describing separate experiences with this procedure in two laboratories in both detection and discrimination tasks. Issues addressed include comparisons with more traditional psychophysical methods, variability in threshold estimates, experimental time required, and possible minor modifications to improve the basic procedure. Results using this procedure are comparable in terms of variability of estimates to those emerging from more lengthy procedures. However, because it may be difficult for some listeners to maintain a consistent criterion and because attentional lapses may be costly, experimenters must be willing to monitor performance closely and repeat some tracks in cases where excessively high variability is noted. Further, this procedure may not be suitable for tasks for which the form of the psychometric function is not well-established. Modifications allowing a variable slope parameter in the maximum-likelihood evaluations of psychometric functions may be of benefit.
Quantitative Estimation of Modulus Variation of Filled Rubbers During Mild Aging Conditions
Authors: Kim Chung Sul Youn
Published: July 2002

Highly filled rubbers undergo both chemical and physical changes during aging. The most commonly observed changes during ambient aging are in: (1) polymer network structure, (2) gel fraction of the binder, and (3) volumetric loading of solids. A quantitative relationship for the modulus change due to the above factors is developed as follows: Es/Er=(νs/νr)⋅(vs/vr)2⋅[(1−φr)/(1−φs)]3 where E is the Young's modulus of the composite, ν is the crosslink density expressed in moles effective chains per cubic centimeter, v is the gel fraction of the binder, φ is the volume filler fraction of the composite, and subscript s and r refer to test specimen and reference material, respectively. Two experiments were performed to evaluate the above relationship: experiment A involved the evaluation of various environmental exposures on thin samples of polybutadiene rubber containing about 76 volume percent solid. Weight loss, swelling ratios, and uniaxial tensile properties were measured. Experiment B involved measurement of the gradient of properties adjacent to the interface between the same filled polybutadiene rubber and lowly filled rubber substrate. Swelling ratios, organic extractables, and uniaxial properties were obtained from thin sections cut from a bulk sample after 18 months storage at 80°F. The experimental data from these studies are used to calculate the reduced modulus, Es/Er, using the above equation. The calculated values agree well with the measured values indicating that the change of modulus is a function of approximately the fifth power of the change in the plasticizer content and approximately the first power of the crosslink density.
Dispersed Two-Phase Flow of Viscoelastic Polymeric Melts in a Circular Tube
Authors: Dae Han Chang , Kim Young Woo
Published: July 2002

An experimental study on the dispersed two-phase flow of visco-elastic polymeric melts has been carried out. For the study, blends of two incompatible polymers, polystyrene and high-density polyethylene, were extruded through a circular tube having an L/D ratio of 20. Mixing was achieved by the combined use of a single-screw extruder and a Static Mixer (Kenics Corp., Thermogenizer). The state of dispersion of one polymer in another was determined from microphotographs taken of extrudate samples. The variables investigated in order to better understand the mechanism of drop formation, were the blending ratio of a mixture, its flow rate, and its melt temperature. In the present study, measurements were taken of wall normal stresses along the longitudinal direction of a capillary die, permitting one to determine both the viscous and elastic properties of the material investigated. It has been found that the viscosity of the blend goes through a minimum and then through a maximum at certain blending ratios, and that the elasticity of the blend goes through a maximum and then through a minimum at certain blending ratios. Interestingly enough, it has been observed that the minimum viscosity occurs at approximately the same blending ratio which gives rise to the maximum elasticity, and that the maximum viscosity occurs at approximately the same blending ratio which gives rise to the minimum elasticity. A phenomenological argument is presented to explain the physical origin of the observed viscoelastic properties of dispersed two-phase polymer systems.
Association of Dexmedetomidine With New-Onset Atrial Fibrillation in Patients With Critical Illness
Authors: Song Myung Jin , Jang Yeonhoon , Lee Ji Hyun , Yoon Joo Heung , Kim Dong Jung , Jung Se Young , Lim Sung Yoon
Published: April 2023

Importance

Dexmedetomidine is a widely used sedative in the intensive care unit (ICU) and has unique properties that may be associated with reduced occurrence of new-onset atrial fibrillation (NOAF).

Objective

To investigate whether the use of dexmedetomidine is associated with the incidence of NOAF in patients with critical illness.

Design, Setting, and Participants

This propensity score–matched cohort study was conducted using the Medical Information Mart for Intensive Care-IV database, which includes records of patients admitted to the ICU at Beth Israel Deaconess Medical Center in Boston dating 2008 through 2019. Included patients were those aged 18 years or older and hospitalized in the ICU. Data were analyzed from March through May 2022.

Exposure

Patients were divided into 2 groups according to dexmedetomidine exposure: those who received dexmedetomidine within 48 hours after ICU admission (dexmedetomidine group) and those who never received dexmedetomidine (no dexmedetomidine group).

Main Outcomes and Measures

The primary outcome was the occurrence of NOAF within 7 days of ICU admission, as defined by the nurse-recorded rhythm status. Secondary outcomes were ICU length of stay, hospital length of stay, and in-hospital mortality.

Results

This study included 22 237 patients before matching (mean [SD] age, 65.9 [16.7] years; 12 350 male patients [55.5%]). After 1:3 propensity score matching, the cohort included 8015 patients (mean [SD] age, 61.0 [17.1] years; 5240 males [65.4%]), among whom 2106 and 5909 patients were in the dexmedetomidine and no dexmedetomidine groups, respectively. Use of dexmedetomidine was associated with a decreased risk of NOAF (371 patients [17.6%] vs 1323 patients [22.4%]; hazard ratio, 0.80; 95% CI, 0.71-0.90). Although patients in the dexmedetomidine group had longer median (IQR) length of stays in the ICU (4.0 [2.7-6.9] days vs 3.5 [2.5-5.9] days; P < .001) and hospital (10.0 [6.6-16.3] days vs 8.8 [5.9-14.0] days; P < .001), dexmedetomidine was associated with decreased risk of in-hospital mortality (132 deaths [6.3%] vs 758 deaths [12.8%]; hazard ratio, 0.43; 95% CI, 0.36-0.52).

Conclusions and Relevance

This study found that dexmedetomidine was associated with decreased risk of NOAF in patients with critical illness, suggesting that it may be necessary and warranted to evaluate this association in future clinical trials.
SGRT‐based DIBH radiotherapy practice for right‐sided breast cancer combined with RNI: A retrospective study on dosimetry and setup accuracy
Authors: Lai Jianjun , Luo Zhizeng , Hu Haili , Jiang Lu , Wu Jing , Lei Lan , Qu Li , Wu Zhibing
Published: April 2023

Background

We retrospectively studied the dosimetry and setup accuracy of deep inspiration breath‐hold (DIBH) radiotherapy in right‐sided breast cancer patients with regional nodal irradiation (RNI) who had completed treatment based on surface‐guided radiotherapy (SGRT) technology by Sentinel/Catalyst system, aiming to clarify the clinical application value and related issues.

Methods

Dosimetric indicators of four organs at risk (OARs), namely the heart, right coronary artery (RCA), right lung, and liver, were compared on the premise that the planning target volume met dose‐volume prescription requirements. Meanwhile, the patients were divided into the edge of the xiphoid process (EXP), sternum middle (SM), and left breast wall (LBW) groups according to different positions of respiratory gating primary points. The CBCT setup error data of the three groups were contrasted for the treatment accuracy study, and the effects of different gating window heights on the right lung volume increases were compared among the three groups.

Results

Compared with free breath (FB), DIBH reduced the maximum dose of heart and RCA by 739.3 ± 571.2 cGy and 509.8 ± 403.8 cGy, respectively (p < 0.05). The liver changed the most in terms of the mean dose (916.9 ± 318.9 cGy to 281.2 ± 150.3 cGy, p < 0.05). The setup error of the EXP group in the anterior‐posterior (AP) direction was 3.6 ± 4.5 mm, which is the highest among the three groups. The right lung volume increases in the EXP, SM, and LBW groups were 72.3%, 69.9%, and 67.2%, respectively (p = 0.08), and the corresponding breath‐holding heights were 13.5 ± 3.7 mm, 10.3 ± 2.4 mm, and 9.6 ± 2.8 mm, respectively (p < 0.05).

Conclusions

SGRT‐based DIBH radiotherapy can better protect the four OARs of right‐sided breast cancer patients with RNI. Different respiratory gating primary points have different setup accuracy and breath‐hold height.
Efficient and Thermally Stable Wide Bandgap Perovskite Solar Cells by Dual‐Source Vacuum Deposition
Authors: Gil‐Escrig Lidón , Susic Isidora , Doğan İlker , Zardetto Valerio , Najafi Mehrdad , Zhang Dong , Veenstra Sjoerd , Sedani Salar , Arikan Bulent , Yerci Selcuk , Bolink Henk J. , Sessolo Michele
Published: April 2023

Wide bandgap perovskites are being widely studied in view of their potential applications in tandem devices and other semitransparent photovoltaics. Vacuum deposition of perovskite thin films is advantageous as it allows the fabrication of multilayer devices, fine control over thickness and purity, and it can be upscaled to meet production needs. However, the vacuum processing of multicomponent perovskites (typically used to achieve wide bandgaps) is not straightforward, because one needs to simultaneously control several thermal sources during the deposition. Here a simplified dual‐source vacuum deposition method to obtain wide bandgap perovskite films is shown. The solar cells obtained with these materials have similar or even larger efficiency as those including multiple A‐cations, but are much more thermally stable, up to 3500 h at 85 °C for a perovskite with a bandgap of 1.64 eV. With optimized thickness, record efficiency of >19% and semitransparent devices with stabilized power output in excess of 17% are achieved.
The Synergistic Effect of Pemirolast Potassium on Carrier Management and Strain Release for High‐Performance Inverted Perovskite Solar Cells
Authors: Li Jun , Xie Lisha , Pu Zhenwei , Liu Chang , Yang Mengjin , Meng Yuanyuan , Han Bin , Bu Shixiao , Wang Yaohua , Zhang Xiaoli , Wang Tao , Ge Ziyi
Published: April 2023

The quality of the perovskite absorption layer is critical for the high efficiency and long‐term stability of perovskite solar cells (PSCs). The inhomogeneity due to local lattice mismatch causes severe residual strain in low‐quality perovskite films, which greatly limits the availability of high‐performance PSCs. In this study, a multi‐active‐site potassium salt, pemirolast potassium (PP), is added to perovskite films to improve carrier dynamics and release residual stress. X‐ray photoelectron spectroscopy (XPS) and Fourier‐transform infrared spectroscopy (FTIR) measurements suggest that the proposed multifunctional additive bonds with uncoordinated Pb2+ through the carbonyl group/tetrazole N and passivated I atom defects. Moreover, the residual stress release is effective from the surface to the entire perovskite layer, and carrier extraction/transport is promoted in PP‐modified perovskite films. As a result, a champion power conversion efficiency (PCE) of 23.06% with an ultra‐high fill factor (FF) of 84.36% is achieved in the PP‐modified device, which ranks among the best in formamidinium‐cesium (FACs) PSCs. In addition, the PP‐modified device exhibits excellent thermal stability due to the inhibited phase separation. This work provides a reliable way to improve the efficiency and stability of PSCs by releasing residual stress in perovskite films through additive engineering.
Platelet Membrane‐Fused Circulating Extracellular Vesicles Protect the Heart from Ischemia/Reperfusion Injury
Authors: Jiang Jizong , Ni Lingyan , Zhang Xinxin , Wang Hongyun , Liu Li , Wei Meng , Li Guoping , Bei Yihua
Published: April 2023

Myocardial ischemia/reperfusion injury (I/RI) may potentiate cardiac remodeling and heart failure, while effective therapies for I/RI remain lacking. Circulating human plasma‐derived extracellular vesicles (hEV) have great potential to protect against I/RI. However, the effective delivery of hEV in vivo remains a limiting factor for clinical application. The present study constructs a biomimetic delivery system of platelet membrane‐fused hEV (P‐hEV), utilizing the natural affinity of platelets for hEV delivery to the injured vascular and myocardial sites. The results show that platelet membrane and hEV membrane fusion can be achieved through repeated extrusion. Compared to non‐modified hEV, P‐hEV uptake is greatly enhanced in human umbilical vein endothelial cells (HUVECs) stressed by oxygen‐glucose deprivation/reperfusion (OGD/R). Functionally, P‐hEV inhibits HUVEC and neonatal rat cardiomyocyte (NRCM) apoptosis and promotes HUVECs migration and tube formation under OGD/R stress in vitro. Intravenous delivery of P‐hEV more effectively targets and accumulates at injury sites in the heart. Furthermore, P‐hEV significantly enhances protection against acute I/RI and attenuates cardiac remodeling at three weeks post‐I/RI. In conclusion, the platelet membrane‐fused hEV delivery system enhances the target delivery of EV to protect against myocardial I/RI, presenting a novel drug delivery system for ischemic heart diseases.
High‐Efficiency Antibacterial Hemostatic AgNP@Zeolite/Chitin/Bamboo Composite Sponge for Wound Healing without Heat Injury
Authors: Zheng Lu , Li Xiaoyun , Xu Changliang , Xu Yidi , Zeng Yukai , Tam Manseng , Zhang Huan‐Tian , Wang Xiaoying
Published: April 2023

Chitin is a popular hemostatic material, but there are still many deficiencies in its ability to effectively stop bleeding, prevent infection, and fit wounds. Herein, AgNP@zeolite/chitin/bamboo (AgZ‐CB) composite sponges with shape recovery are prepared to minimize blood loss, kill bacteria, and promote wound healing. Notably, the bamboo powder is used for the first time to remarkably enhance the softness of the composite sponge (volumetric expansion ratio >5). The fabricated AgZ‐CB sponge exhibits an excellent killing effect (≈100% bactericidal rate) against both Escherichia coli and Staphylococcus aureus and activates internal and external coagulation pathways to accelerate hemostasis without causing thermal damage (≈5 °C temperature difference). Moreover, the AgZ‐CB sponge shows less blood loss (26 mg) and a shorter time to hemostasis (42 s) than the commercial polyvinyl formal sponge (84 mg and 76 s) in the full‐thickness liver injury model. The in vivo wound healing and biodegradation experiment indicate that AgZ‐CB with excellent biocompatibility can close wounds efficiently. Overall, the AgZ‐CB sponge has great potential in combating a series of obstacles in wound healing.
Gate‐Controlled Magnetotransport and Electrostatic Modulation of Magnetism in 2D Magnetic Semiconductor CrPS4
Authors: Wu Fan , Gibertini Marco , Watanabe Kenji , Taniguchi Takashi , Gutiérrez‐Lezama Ignacio , Ubrig Nicolas , Morpurgo Alberto F.
Published: April 2023

Using field‐effect transistors (FETs) to explore atomically thin magnetic semiconductors with transport measurements is difficult, because the very narrow bands of most 2D magnetic semiconductors cause carrier localization, preventing transistor operation. Here, it is shown that exfoliated layers of CrPS4—a 2D layered antiferromagnetic semiconductor whose bandwidth approaches 1 eV—allow the realization of FETs that operate properly down to cryogenic temperature. Using these devices, conductance measurements as a function of temperature and magnetic field are performed to determine the full magnetic phase diagram, which includes a spin‐flop and a spin‐flip phase. The magnetoconductance, which depends strongly on gate voltage, is determined. reaching values as high as 5000% near the threshold for electron conduction. The gate voltage also allows the magnetic states to be tuned, despite the relatively large thickness of the CrPS4 multilayers employed in the study. The results show the need to employ 2D magnetic semiconductors with sufficiently large bandwidth to realize properly functioning transistors, and identify a candidate material to realize a fully gate‐tunable half‐metallic conductor.
Hydrogels and Bioprinting in Bone Tissue Engineering: Creating Artificial Stem‐Cell Niches for In Vitro Models
Authors: Lewns Francesca K. , Tsigkou Olga , Cox Liam R. , Wildman Ricky D. , Grover Liam M. , Poologasundarampillai Gowsihan
Published: April 2023

Advances in bioprinting have enabled the fabrication of complex tissue constructs with high speed and resolution. However, there remains significant structural and biological complexity within tissues that bioprinting is unable to recapitulate. Bone, for example, has a hierarchical organization ranging from the molecular to whole organ level. Current bioprinting techniques and the materials employed have imposed limits on the scale, speed, and resolution that can be achieved, rendering the technique unable to reproduce the structural hierarchies and cell–matrix interactions that are observed in bone. The shift toward biomimetic approaches in bone tissue engineering, where hydrogels provide biophysical and biochemical cues to encapsulated cells, is a promising approach to enhancing the biological function and development of tissues for in vitro modeling. A major focus in bioprinting of bone tissue for in vitro modeling is creating dynamic microenvironmental niches to support, stimulate, and direct the cellular processes for bone formation and remodeling. Hydrogels are ideal materials for imitating the extracellular matrix since they can be engineered to present various cues whilst allowing bioprinting. Here, recent advances in hydrogels and 3D bioprinting toward creating a microenvironmental niche that is conducive to tissue engineering of in vitro models of bone are reviewed.
Multifunctional Metal‐Organic Frameworks Capsules Modulate Reactivity of Lead Iodide toward Efficient Perovskite Solar Cells with UV Resistance
Authors: Sheng Wangping , He Jiacheng , Yang Jia , Cai Qianqian , Xiao Shuqin , Zhong Yang , Tan Licheng , Chen Yiwang
Published: April 2023

The two‐step sequential deposition process is demonstrated as a reliable technology for the fabrication of efficient perovskite solar cells (PVSCs). However, the complete conversion of dense PbI2 to perovskite in planar PVSCs is tough without mesoporous titanium dioxide as support. Herein, multifunctional capsules consisting of zeolitic imidazolate framework‐8 (ZIF‐8) encapsulant and formamidinium iodide (FAI) are introduced between tin oxide (SnO2) and lead iodide (PbI2) layer. Intriguingly, the capsule dopant interlayer benefits the formation of porous PbI2 film due to the porous nanostructure of ZIF‐8 that is favorable for the subsequent intercalation reaction. Furthermore, the constituent of the perovskite precursor in ZIF‐8 pores can convert into the crystal nuclei of perovskite by reacting with PbI2 first, thereby promoting further perovskite crystallization. Significantly, the incorporation of ZIF‐8 can enhance the resistance of perovskite against UV illumination due to down‐conversion effect. Consequently, the modified device achieves a champion power conversion efficiency (PCE) of 24.08% and displays enhanced UV stability, which can sustain 83% of its original PCE under 365 nm UV illumination for 300 h. Moreover, the unencapsulated device maintains 90% of initial PCE after 1500 h storage in dark ambient conditions with a relative humidity range of 50%–70%.
Water‐Based Conductive Ink Formulations for Enzyme‐Based Wearable Biosensors
Authors: Tricase Angelo , Imbriano Anna , Valentino Marlene , Ditaranto Nicoletta , Macchia Eleonora , Franco Cinzia Di , Kidayaveettil Reshma , Leech Dónal , Piscitelli Matteo , Scamarcio Gaetano , Perchiazzi Gaetano , Torsi Luisa , Bollella Paolo
Published: April 2023

Herein, this work reports the first example of second‐generation wearable biosensor arrays based on a printed electrode technology involving a water‐based graphite ink, for the simultaneous detection of l‐lactate and d‐glucose. The water‐based graphite ink is deposited onto a flexible polyethylene terephthalate sheet, namely stencil‐printed graphite (SPG) electrodes, and further modified with [Os(bpy)2(Cl)(PVI)10] as an osmium redox polymer to shuttle the electrons from the redox center of lactate oxidase from Aerococcus viridans (LOx) and gluocose oxidase from Aspergillus niger (GOx). The proposed biosensor array exhibits a limit of detection as low as (9.0 ± 1.0) × 10−6 m for LOx/SPG‐[Os(bpy)2(Cl)(PVI)10] and (3.0 ± 0.5) × 10−6 m for GOx/SPG‐[Os(bpy)2(Cl)(PVI)10], a sensitivity as high as 1.32 μA mm−1 for LOx/SPG‐[Os(bpy)2(Cl)(PVI)10] and 28.4 μA mm−1 for GOx/SPG‐[Os(bpy)2(Cl)(PVI)10]. The technology is also selective when tested in buffer and artificial sweat and is endowed with an operational/storage stability of ≈80% of the initial signal retained after 20 days. Finally, the proposed array is integrated in a wristband and successfully tested for the continuous monitoring of l‐lactate and d‐glucose in a healthy volunteer during daily activity. This is foreseen as a real‐time wearable device for sport‐medicine and healthcare applications.
Kirigami–Origami‐Inspired Lead‐Free Piezoelectric Ceramics
Authors: Wang Zehuan , Ma Denghao , Wang Yunhan , Xie Yan , Yu Zhonghui , Cheng Jin , Li Li , Sun Liang , Dong Shuxiang , Wang Hong
Published: April 2023

Kirigami‐ and oirigami‐inspired techniques have emerged as effective strategies for material structure design; however, the use of these techniques is usually limited to soft and deformable materials. Piezoelectric ceramics, which are typical functional ceramics, are widely used in electronic and energy devices; however, the processing options for piezoelectric ceramics are limited by their brittleness and feedstock viscosity. Here, a design strategy is proposed for the preparation of lead‐free piezoelectric ceramics inspired by kirigami/origami. This strategy involves direct writing printing and control over the external gravity during the calcination process for the preparation of curved and porous piezoelectric ceramics with specific shapes. The sintered BaTiO3 ceramics with curved geometries produced using this strategy exhibit a high piezoelectric constant (d33 = 275 pC N−1), which is 45% higher than that of conventionally sintered sheet ceramics. The curved structure of the ceramics is well‐suited for use in the human body and it was determined that these curved ceramics can detect pulse signals. This strategy can be applied in the large‐scale and low‐cost production of other piezoelectric ceramics with various curved shapes and provides a new approach for the preparation of complex‐shaped ceramics.
Copper‐Zinc Bimetallic Single‐Atom Catalysts with Localized Surface Plasmon Resonance‐Enhanced Photothermal Effect and Catalytic Activity for Melanoma Treatment and Wound‐Healing
Authors: Liu Lidan , Zhang Haifeng , Xing Shun , Zhang Yu , Shangguan Li , Wei Chao , Peng Feng , Liu Xuanyong
Published: April 2023

Nanomaterials with photothermal combined chemodynamic therapy (PTT‐CDT) have attracted the attention of researchers owing to their excellent synergistic therapeutic effects on tumors. Thus, the preparation of multifunctional materials with higher photothermal conversion efficiency and catalytic activity can achieve better synergistic therapeutic effects for melanoma. In this study, a Cu–Zn bimetallic single‐atom (Cu/PMCS) is constructed with augmented photothermal effect and catalytic activity due to the localized surface plasmon resonance (LSPR) effect. Density functional theory calculations confirmed that the enhanced photothermal effect of Cu/PMCS is due to the appearance of a new d‐orbital transition with strong spin‐orbit coupling and the induced LSPR. Additionally, Cu/PMCS exhibited increased catalytic activity in the Fenton‐like reaction and glutathione depletion capacity, further enhanced by increased temperature and LSPR. Consequently, Cu/PMCS induced better synergistic anti‐melanoma effects via PTT‐CDT than PMCS in vitro and in vivo. Furthermore, compared with PMCS, Cu/PMCS killed bacteria more quickly and effectively, thus facilitating wound healing owing to the enhanced photothermal effect and slow release of Cu2+. Cu/PMCS promoted cell migration and angiogenesis and upregulated the expression of related genes to accelerate wound healing. Cu/PMCS has potential applications in treating melanoma and repairing wounds with its antitumor, antibacterial, and wound‐healing properties.
Multiple Electronic Phases Coexisting under Inhomogeneous Strains in the Correlated Insulator
Authors: Hou Baofei , Zhang Yu , Zhang Teng , Wu Jizheng , Zhang Quanzhen , Han Xu , Huang Zeping , Chen Yaoyao , Ji Hongyan , Wang Tingting , Liu Liwei , Si Chen , Gao Hong‐Jun , Wang Yeliang
Published: April 2023

Monolayer transition metal dichalcogenides (TMDs) can host exotic phenomena such as correlated insulating and charge‐density‐wave (CDW) phases. Such properties are strongly dependent on the precise atomic arrangements. Strain, as an effective tuning parameter in atomic arrangements, has been widely used for tailoring material's structures and related properties, yet to date, a convincing demonstration of strain‐induced dedicate phase transition at nanometer scale in monolayer TMDs has been lacking. Here, a strain engineering technique is developed to controllably introduce out‐of‐plane atomic deformations in monolayer CDW material 1T‐NbSe2. The scanning tunneling microscopy and spectroscopy (STM and STS) measurements, accompanied by first‐principles calculations, demonstrate that the CDW phase of 1T‐NbSe2 can survive under both tensile and compressive strains even up to 5%. Moreover, significant strain‐induced phase transitions are observed, i.e., tensile (compressive) strains can drive 1T‐NbSe2 from an intrinsic‐correlated insulator into a band insulator (metal). Furthermore, experimental evidence of the multiple electronic phase coexistence at the nanoscale is provided. The results shed new lights on the strain engineering of correlated insulator and useful for design and development of strain‐related nanodevices.
Robust Anode‐Free Sodium Metal Batteries Enabled by Artificial Sodium Formate Interface
Authors: Wang Chaozhi , Zheng Ying , Chen Zhe‐Ning , Zhang Rongrong , He Wei , Li Kaixuan , Yan Sen , Cui Jingqin , Fang Xiaoliang , Yan Jiawei , Xu Gang , Peng Dongliang , Ren Bin , Zheng Nanfeng
Published: April 2023

Sodium metal batteries (NMBs) have attracted increasing attention as next‐generation rechargeable batteries. How to improve their cycling stability and safety under limited sodium excess conditions, ideally zero sodium excess (i.e., anode‐free architecture), is highly desired yet remains challenging. Herein, it is demonstrated that sodium formate (HCOONa), one component of the solid electrolyte interphase (SEI) naturally formed on sodium metal anode, is a promising candidate for designing high‐performance artificial SEI layers, which can suppress the sodium dendrite formation and reduce the side reactions between sodium and the electrolyte. Profiting from the HCOONa interface, the Na|Na3V2(PO4)3 battery with a high mass loading of Na3V2(PO4)3 (10 mg cm−2) exhibits a superior cycling stability with an ultralow decay rate of 0.004% per cycle over 800 cycles. More impressively, a single molecular layer of HCOONa in situ formed on commercial copper current collector helps to extend the lifespan of the anode‐free Cu|Na3V2(PO4)3 battery to 400 cycles with 88.2% capacity relation, representing the longest cycle lifetime reported in anode‐free NMBs.
Nanocrystal‐Enabled Perovskite Heterojunctions in Photovoltaic Applications and Beyond
Authors: Wieliczka Brian M. , Habisreutinger Severin N. , Schutt Kelly , Blackburn Jeffrey L. , Luther Joseph M.
Published: April 2023

Heterojunctions are used to tailor the properties of semiconductors in optoelectronic devices, yet for emerging devices composed of metal halide perovskites, fabricating perovskite/perovskite heterojunctions has proved challenging due to solvent incompatibilities and rapid homogenization due to ion migration. Recent studies have demonstrated various strategies for using perovskite nanocrystals as a component to fabricate perovskite/perovskite heterojunctions, either with a perovskite thin film or a second nanocrystal layer. Heterojunctions such as these can impart many advantages of both bulk and nanocrystalline perovskite morphologies. This perspective focuses on recent developments of solution‐processed perovskite heterojunctions for solar cells and novel optoelectronic devices, in particular, highlighting the demonstrated and potential advantages of nanocrystal‐enabled fabrication strategies. A central tenet of this perspective is that the synthesis and dispersion of perovskite nanocrystals in non‐polar organic solvents offers a key processing advantage over traditional perovskite precursor solutions in polar solvents since the former allows for layer‐by‐layer deposition without dissolving an underlying perovskite film or crystal. This processing advantage, coupled with nanocrystal size control and ligand chemistry, enables perovskite heterojunctions with highly tunable optical and electrical properties. Such heterojunctions may enable disruptive technological advances in broad classes of devices such as solar cells, photodetectors, sensors, and (in)coherent photon sources with tunable polarization.
Pd Sulfidation‐Induced 1T‐Phase Tuning in Monolayer MoS2 for Hydrogen Evolution Reaction
Authors: Mai Hien Duy , Jeong Sangmin , Bae Gi‐Nam , Tran Ngoc Minh , Youn Jong‐Sang , Park Cheol‐Min , Jeon Ki‐Joon
Published: April 2023

For single‐atom‐layer hydrogen evolution reaction catalysts, enrichment of the 1T‐phase in monolayer molybdenum disulfide is important to achieve ideal metal utilization efficiency and exposure of active surface atoms. Herein, it is discovered that the 1T‐phase degree in monolayer MoS2 can be enhanced through sulfidation of the Pd species deposited on MoS2 (PdxSy/1T‐MoS2). Raman and X‐ray photoelectron spectroscopy reveal that the sulfidation‐assisted phase transition results in considerably greater proportions of 1T‐phase fraction (up to 86%) without using alkali‐metal‐based approaches. Observations of S‐atom displacement/translation at the atomic level contribute to the understanding of the phase transformation of MoS2. The maximized surface atom activation and metal utilization efficiency in PdxSy/1T‐MoS2 lead to unprecedentedly high mass activity (−3444 A mgPd−1) and turnover frequency (1892 s−1), three orders of magnitude higher than those of commercial Pt/C 10 wt% (3.6 A mgPt−1 and 3.6 s−1). The sulfidation‐assisted 1T‐phase enrichment has major implications for the designs of efficient electrocatalysts through MoS2 phase engineering.
Triggering Mixed Cationic‐Anionic Redox in Cu2‐xSe Cathodes via Tailored Charge‐Carrier for High Energy Density Aqueous Zn Batteries
Authors: Yao Zeying , Yang Junwei , Ren Zhiguo , Ren Xiaochuan , Sun Yuanhe , Zhao Yuanxin , Si Jingying , Lei Qi , Zhang Wei , Li Zhao , Yin Yaru , Chen Jige , Wen Wen , Zhu Daming , Li Xiaolong , Tai Renzhong
Published: April 2023

The further application of promising transition‐metal chalcogenides (TMCs) cathodes in dilute neutral aqueous Zn batteries (AZBs) is mainly plagued by unsatisfactory working voltages (usually <1 V vs Zn2+/Zn) and their conventional cationic redox centers reaching theoretical capacity limit. Hence, to break the confinement, a novel Zn‐Cu2‐xSe battery is developed in dilute neutral‐aqueous electrolyte by introducing a tailored charge‐carrier, which not only alters the intercalation potential of ions embedded into Cu2‐xSe (vs Zn2+/Zn, working voltage from ≈0.4 to ≈1.2 V) but also activates the anionic redox centers of Cu2‐xSe (capacity release from 143.4 to 323.2 mAh g−1 at 0.4 A g−1). In situ synchrotron X‐ray diffraction (SXRD) and substantial ex situ characterizations reveal the multi‐step phase conversion undergone by cathode and triggered additional Se‐based anionic (Sen2−/Se2−) reversible redox reaction. A multi‐electron synergistic transfer process established on the cationic‐anionic redox centers circumvents the slow relaxation of single‐ion charge compensation achieving high‐capacity and enhanced ion diffusion kinetics. As a result, an extraordinary energy density of up to 406.2 Wh kg−1 at 240 W kg−1 is implemented (calculated based on the mass of Cu2‐xSe cathode), which is ≈8.4 times higher than that of conventional Zn‐Cu2‐xSe batteries, representing an advanced development toward energetic AZBs.
Revealing and Optimizing the Dialectical Relationship Between NOR and OER: Cation Vacancy Engineering Enables RuO2 With Unanticipated High Electrochemical Nitrogen Oxidation Performance
Authors: Xu Fanfan , Liu Xia , Zhang Linlin , Guo Mingxia , Li Mingzhu , Ding Xin , Zhang Lixue
Published: April 2023

The electrochemical N2 oxidation reaction (NOR) using water and atmospheric N2 represents a sustainable approach to nitric acid production; while, the parasitic oxygen evolution reaction (OER) usually results in poor conversion selectivity of N2 oxidation. Although the side‐reaction can be partially suppressed by using OER‐inactive catalysts or substrates, the optimized performance is usually obtained at the cost of low yield. Revealing the internal relationship between NOR and OER, providing an effective pathway to optimize the dialectical relationship between OER and NOR is desirable and of socio‐economic significance. Herein, RuO2, the well‐known OER electrocatalyst, is defectively engineered to enhance the cooperation rather than competition between NOR and OER; a Faradaic efficiency (FE) of 6.70% at 1.36 V and a maximum yield of 767.92 µg h−1 mgcat−1 at 1.44 V are obtained on D‐RuO2 in acid electrolyte, superior to all the previously reported works. Experiments and DFT calculations suggest that the OER intermediates play a crucial role and the real rate‐determining step during nitrogen oxidation is the transition from *O to *OOH involved in the formation of *NN(OH). The outstanding NOR activity is ascribed to the enhanced stabilization of *OH and the promotion of OO bond breakage in the rate determining step of *NN(OH) formation.