bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo‐aided dosimetry of the Source Tech Medical Model STM1251 I‐125 interstitial brachytherapy source
Authors: Kirov Assen S. , Williamson Jeffrey F.
Published: July 2002

We have used Monte Carlo photon transport simulations to calculate the dosimetric parameters of a new seed, the Source Tech Medical Model STM1251 source for interstitial brachytherapy. We followed the recommendations of the AAPM Task Group 43 and determined the following parameters: dose‐rate constant, radial dose function, anisotropy function, anisotropy factor, and anisotropy constant. The recently (January 1999) revised National Institute of Standards and Technology I‐125 standard for air‐kerma strength calibration was taken into account as well as updated interaction cross‐section data. The calculated dose‐rate constant, when normalized to the simulated wide‐angle, free‐air chamber measurement of air‐kerma strength, is 0.980 cGy h−1 U−1. The calculated radial dose function for the Model STM1251 source is more penetrating than that of the model 6711 seed (by 18% at 5 cm distance), but agrees closely (within statistical errors) with that of the model 6702 seed up to distances of 10 cm. The STM1251 source anisotropy functions indicate that its dose distribution is somewhat more anisotropic than that of the model 6702 and 6711 seeds at 1 cm distance but is comparable at larger distances. The Model STM1251 anisotropy constant is very similar to that of the model 6711, 6702, and MED3631 A/M seeds.
Thermoluminescent dosimetry of the selectSeed interstitial brachytherapy seed
Authors: Anagnostopoulos G. , Baltas D. , Karaiskos P. , Sandilos P. , Papagiannis P. , Sakelliou L.
Published: July 2002

This work presents experimental dosimetry results for the new selectSeed prostate seed design for use with the seedSelectron afterloading device, in accordance with the AAPM advisory that all new low energy interstitial brachytherapy seeds should undergo one Monte Carlo (MC) and at least one experimental dosimetry characterization. TLD dosimetry was performed using 120 cylindrical LiF TLD type‐100 rods calibrated using a 6 MV photon beam. They were irradiated in solid water phantoms for the experimental determination of the seed dose rate constant, radial dose functions and anisotropy functions. MC simulations were performed for the determination of the TLDs relative energy response that was found position independent and equal to and for the calculation of the ratio of dose in liquid water to dose in solid water that was found to be well described by presenting only a minor dependence on polar angle. The selectSeed dose rate constant in liquid water was found equal to which agrees within experimental uncertainties with corresponding MC results of The experimental radial dose and anisotropy function results were also found in good agreement with corresponding MC calculations.
A sector‐integration method for calculating the output factors of irregularly shaped electron fields
Authors: Jursinic Paul A. , Mueller Richard
Published: July 2002

An empirical model is presented that uses a sector‐integration method for calculating the output factors of irregularly shaped electron fields. The sector‐integration method accounts for changes in electron fluence, lateral scatter equilibrium, and scatter from the edge of a cutout shield. This method is tested for elliptical and rectangular fields with a ratio of the long‐to‐short axis as great as 4 to 1. Differences between measured and calculated values for output factors were less than ±1%. Comparisons were also carried out for a large number of cutout shields that were used in the clinic and similar levels of accuracy were obtained.
Electrocardiogram‐correlated image reconstruction from subsecond spiral computed tomography scans of the heart
Authors: Kachelriess Marc , Kalender Willi A.
Published: July 2002

Subsecond computed tomography (CT) scanning offers potential for improved heart imaging. We therefore developed and validated dedicated reconstruction algorithms for imaging the heart with subsecond spiral CT utilizing electrocardiogram (ECG) information. We modified spiral CT z‐interpolation algorithms on a subsecond spiral CT scanner. Two new classes of algorithms were investigated: (a) 180°CI (cardio interpolation), a piecewise linear interpolation between adjacent spiral data segments belonging to the same heart phase where segments are selected by correlation with the simultaneously recorded ECG signal and (b) 180°CD (cardio delta), a partial scan reconstruction of with angle, resulting in reduced effective scan times of less than 0.5 s. Computer simulations as well as processing of clinical data collected with 0.75 s scan time were carried out to evaluate these new approaches. Both 180°CI and 180°CD provided significant improvements in image quality. Motion artifacts in the reconstructed images were largely reduced as compared to standard spiral reconstructions; in particular, coronary calcifications were delineated more sharply and multiplanar reformations showed improved contiguity. However, new artifacts in the image plane are introduced, mostly due to the combination of different data segments. ECG‐oriented image reconstructions improve the quality of heart imaging with spiral CT significantly. Image quality and the display of coronary calcification appear adequate to assess coronary calcium measurements with conventional subsecond spiral CT.
Signal‐to‐noise ratio and spatial resolution in x‐ray electronic imagers: Is the MTF a relevant parameter?
Authors: Moy Jean‐Pierre
Published: July 2002

In most imaging detectors, the modulation transfer function (MTF) is regarded as a good parameter to describe spatial resolution. This is undoubtedly valid for visual observation. However, the detectability of a detail is essentially a matter of signal‐to‐noise ratio, which is not accounted for by the MTF. In x‐ray imaging, signal‐to‐noise ratio in the image is generally limited by incident photons statistics, often larger than readout noises. Therefore, the MTF of the detector applies to both signal and noise, and does not impair the image content. Contrast can easily be restored by image processing without altering the signal‐to‐noise ratio. However, a number of effects may alter very differently noise and signal: (i) If the MTF significantly extends beyond half the sampling frequency, the aliasing introduced by spatial sampling can severely enhance the noise and cancel the benefit of the good signal transfer. This is illustrated by synthetic images which simulate the response of imagers with different MTFs to the same test pattern in the presence of quantum noise. (ii) Parallax and blurring by the x‐ray spot size or motion are shown to degrade the transfer properties of signal, but do not affect the quantum noise; they must be treated separately. Contrary to the x‐ray converter MTF, parallax directly impacts the detective quantum efficiency (DQE). Finally, it is shown that only the detective quantum efficiency can reliably describe the spatial resolution of an x‐ray imaging detector in the presence of noise, parallax and blurring.
Cosmological expansion in the classroom
Authors: Price Richard H. , Grover Elizabeth
Published: July 2002

A simple demonstration or classroom exercise using the expansion of a latex strip provides an analog computation of the light travel time between distant galaxies in an expanding universe, and gives students insight into the meaning of cosmological expansion.
The single particle potential in mean-field theory
Authors: Palffy-Muhoray Peter
Published: July 2002

The problem of determining the single particle energy in a mean-field description of interacting particles is considered. It is shown that the single particle energy must satisfy two consistency conditions, and a general procedure for obtaining the single particle energy from the pair energy is proposed. Interacting dipolar systems are examined, current approaches in the literature are discussed, and the usefulness of the proposed method is demonstrated.
Transforming the lecture-hall environment: The fully interactive physics lecture
Authors: Meltzer David E. , Manivannan Kandiah
Published: July 2002

Numerous reports suggest that learning gains in introductory university physics courses may be increased by “active-learning” instructional methods. These methods engender greater mental engagement and more extensive student–student and student–instructor interaction than does a typical lecture class. It is particularly challenging to transfer these methodologies to the large-enrollment lecture hall. We report on seven years of development and testing of a variant of Peer Instruction as pioneered by Mazur that aims at achieving virtually continuous instructor–student interaction through a “fully interactive” physics lecture. This method is most clearly distinguished by instructor–student dialogues that closely resemble one-on-one instruction. We present and analyze a detailed example of such classroom dialogues, and describe the format, procedures, and curricular materials required for creating the desired lecture-room environment. We also discuss a variety of assessment data that indicate strong gains in student learning, consistent with other researchers. We conclude that interactive-lecture methods in physics instruction are practical, effective, and amenable to widespread implementation.
Phase shifts in multilayer dielectric beam splitters
Authors: Hamilton M. W.
Published: July 2002

Some properties of the reflectivity and transmissivity of multilayer dielectric optical coatings are derived from energy conservation applied to a beam splitter acting as a beam combiner. It is shown that dispersion in the phase shifts of the beam splitter coatings influences which quadrature amplitude is measured in a homodyne detector, and, in a Michelson interferometer, how the white-light fringe pattern is disposed about the zero-path-difference condition. The functions of reflectivity and transmissivity that determine these properties are shown to be not completely constrained by considerations of energy conservation and time reversibility, in contrast to commonly employed models for beam splitter reflectivity and transmissivity. Some representative beam splitter coating designs are used to illustrate this point.
Acoustic noise during functional magnetic resonance imaging
Authors: Ravicz Michael E. , Melcher Jennifer R. , Kiang Nelson Y.-S.
Published: July 2002

Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For studies of the auditory system, acoustic noise generated during fMRI can interfere with assessments of this activation by introducing uncontrolled extraneous sounds. As a first step toward reducing the noise during fMRI, this paper describes the temporal and spectral characteristics of the noise present under typical fMRI study conditions for two imagers with different static magnetic field strengths. Peak noise levels were 123 and 138 dB re 20 μPa in a 1.5-tesla (T) and a 3-T imager, respectively. The noise spectrum (calculated over a 10-ms window coinciding with the highest-amplitude noise) showed a prominent maximum at 1 kHz for the 1.5-T imager (115 dB SPL) and at 1.4 kHz for the 3-T imager (131 dB SPL). The frequency content and timing of the most intense noise components indicated that the noise was primarily attributable to the readout gradients in the imaging pulse sequence. The noise persisted above background levels for 300–500 ms after gradient activity ceased, indicating that resonating structures in the imager or noise reverberating in the imager room were also factors. The gradient noise waveform was highly repeatable. In addition, the coolant pump for the imager’s permanent magnet and the room air-handling system were sources of ongoing noise lower in both level and frequency than gradient coil noise. Knowledge of the sources and characteristics of the noise enabled the examination of general approaches to noise control that could be applied to reduce the unwanted noise during fMRI sessions.
Dynamic articulatory model based on multidimensional invariant-feature task representation
Authors: Kaburagi Tokihiko , Honda Masaaki
Published: July 2002

A dynamic model of articulatory movements is introduced. The research presented herein focuses on the method of representing the phonemic tasks, i.e., phoneme-specific articulatory targets. Phonemic tasks in our model are formally defined using invariant features of articulatory posture. The invariant features used in the model are characterized by the linear transformation of articulatory variables and found using a statistical analysis of measured articulatory movements, in which the articulatory features with minimum variability are taken to be the invariant features. Articulatory movements making vocal-tract constrictions or relative movements among articulators reflecting task-sharing structures are typical examples of the features found to have low variability. In the trajectory formation of articulatory movements, the dimension number of the phonemic task is set at a smaller value than that of articulatory variables. Consequently, the kinematic states of the articulators are partly constrained at given time instants by a sequence of phonemic tasks, and there remain unconstrained degrees of freedom of articulatory variables. Articulatory movements are determined so that they simultaneously satisfy given phonemic tasks and dynamic smoothness constraints. The dynamic smoothness constraints coupled with the underspecified phonemic targets allow our model to explain contextual articulatory variability using context-independent phonemic tasks. Finally, the capability of the model for predicting actual articulatory movements is quantitatively investigated using empirical articulatory data.
Thin coating characterization by Rayleigh waves: An analytical model based on normal-mode theory
Authors: Windels Filip W. , Vanaverbeke S. , Leroy O.
Published: July 2002

The acousto-optic technique to evaluate coated substrates, presented by Devolder et al. [Appl. Phys. Lett. 68, 1732 (1996)], uses the phase dependence of the reflected beam on the coating parameters. In this theoretical paper, a fully analytical model, based on normal-mode theory, is applied to this problem. It gives a transparent expression for the phase shift between the reflected and the incident field due to the presence of thin coatings (coating thickness much smaller than wavelength sound). The known numerical results from Fourier simulations, i.e. the phase dependency on the coating parameters and the advantages of using higher frequencies and wider beams, are reproduced. However, thanks to the analytical nature of the new theory, additional results are obtained. The calculation time is reduced by two orders of magnitude, which is important for the inverse problem. A technique for absolute thickness measurements is proposed. Measuring more to the right of the second reflected maximum increases the phase sensitivity. The versatility of the normal-mode approach is illustrated by applying it to other nondestructive testing (NDT) applications, such as hardness determination and adhesion testing, which are briefly discussed.
Computed narrow-band azimuthal time-reversing array retrofocusing in shallow water
Authors: Dungan Michael R. , Dowling David R.
Published: July 2002

The process of acoustic time reversal sends sound waves back to their point of origin in reciprocal acoustic environments even when the acoustic environment is unknown. The properties of the time-reversed field commonly depend on the frequency of the original signal, the characteristics of the acoustic environment, and the configuration of the time-reversing transducer array (TRA). In particular, vertical TRAs are predicted to produce horizontally confined foci in environments containing random volume refraction. This article validates and extends this prediction to shallow water environments via monochromatic Monte Carlo propagation simulations (based on parabolic equation computations using RAM). The computational results determine the azimuthal extent of a TRA’s retrofocus in shallow-water sound channels either having random bottom roughness or containing random internal-wave-induced sound speed fluctuations. In both cases, randomness in the environment may reduce the predicted azimuthal angular width of the vertical TRA retrofocus to as little as several degrees (compared to 360 degrees for uniform environments) for source-array ranges from 5 to 20 km at frequencies from 500 Hz to 2 kHz. For both types of randomness, power law scalings are found to collapse the calculated azimuthal retrofocus widths for shallow sources over a variety of acoustic frequencies, source-array ranges, water column depths, and random fluctuation amplitudes and correlation scales. Comparisons are made between retrofocusing on shallow and deep sources, and in strongly and mildly absorbing environments.
On the detection of early cochlear damage by otoacoustic emission analysis
Authors: Lucertini M. , Moleti A. , Sisto R.
Published: July 2002

Theoretical considerations and experimental evidence suggest that otoacoustic emission parameters may be used to reveal early cochlear damage, even before it can be diagnosed by standard audiometric techniques. In this work, the statistical distributions of a set of otoacoustic emission parameters chosen as candidates for the early detection of cochlear damage (global and band reproducibility, response level, signal-to-noise ratio, spectral latency, and long-lasting otoacoustic emission presence) were analyzed in a population of 138 ears. These ears have been divided, according to a standard audiometric test, in three classes: (1) ears of nonexposed bilaterally normal subjects, (2) normal ears of subjects with unilateral noise-induced high-frequency hearing loss, and (3) their hearing impaired ears. For all analyzed parameters, a statistically significant difference was found between classes 1 and 2. This difference largely exceeds the difference observed between classes 2 and 3. This fact suggests that the noise exposure, which was responsible for the unilateral hearing loss, also caused subclinical damage in the contralateral, audiometrically normal, ear. This is a clear indication that otoacoustic emission techniques may be able to early detect subclinical damages.
Excess attenuation of leaky Lamb waves due to viscous fluid loading
Authors: Nayfeh Adnan H. , Nagy Peter B.
Published: July 2002

In two recent papers [J. Acoust. Soc. Am. 97, 3191–3193 (1995) and 98, 1057–1064 (1995)], Zhu and Wu presented an analytical technique to assess the effect of viscous fluid loading on the propagation properties of Rayleigh and Lamb waves in fluid-loaded solids. They modeled the viscous fluid as a hypothetical isotropic solid having rigidity c55=−iωη, where η denotes the viscosity of the fluid and ω is the angular frequency. In this way, the vorticity mode associated with the viscosity of the fluid is formally described as the shear-mode in the fictitious solid. In this paper this technique is further developed by removing certain inconsistencies that unnecessarily reduce the accuracy and the range of validity of Zhu and Wu’s results. By properly accounting for viscous effects on the bulk compressional wave in the fluid and applying a rigorous treatment of the field equations and boundary conditions, the exact dispersion equations that are not limited to low frequencies and viscosities are derived. Examples of these results are presented to illustrate the effect of fluid viscosity on the lowest-order symmetric and antisymmetric Lamb modes. One interesting feature revealed by these calculations is the presence of a sharp minimum in the viscosity induced attenuation of the lowest-order symmetric mode of thin plates either immersed in or coated with a viscous fluid. This minimum occurs at a particular frequency where the otherwise elliptical polarization of the surface vibration becomes linearly polarized in the normal direction.
Helmholtz equation–least-squares method for reconstructing acoustic pressure fields
Authors: Wang Zhaoxi , Wu Sean F.
Published: July 2002

A method using spherical wave expansion theory to reconstruct an acoustic pressure field from a vibrating object is developed. The radiated acoustic pressures are obtained by means of an expansion of independent functions generated by the Gram–Schmidt orthonormalization with respect to the particular solutions to the Helmholtz equation on the vibrating surface under consideration. The coefficients associated with these independent functions are determined by requiring the assumed form of the solution to satisfy the pressure boundary condition at the measurement points. The errors incurred in this process are minimized by the least-squares method. Once these coefficients are specified, the acoustic pressure at any point, including the source surface, is completely determined. In this paper, this method is used to reconstruct the surface acoustic pressures based on the measured acoustic pressure signals in the field. It is shown that this method can be applied to both separable and nonseparable geometries, and the solutions thus obtained are unique. However, the convergence may be worse for an elongated object subject to high-frequency excitations. [Work supported by the Institute for Manufacturing Research at Wayne State University.]
Laser ultrasonic chirp sources for low damage and high detectability without loss of temporal resolution
Authors: Murray Todd W. , Baldwin Kevin C. , Wagner James W.
Published: July 2002

Linear frequency-modulated (chirped) acoustic signals have been generated using a pulsed laser spatially modulated by an absorption mask at the surface of a test material. By distributing the laser energy over an area, instead of focusing it to a point or line source, the peak power density of the laser source can be kept below the damage threshold of the material. The corresponding chirped ultrasonic surface wave packet produced by the source, although extended in time, is detected and processed using a matched filtering technique which compresses the packet into a pulse, thus preserving temporal resolution for accurate time-of-flight measurements. Matched filter processing of the chirped wave packet has been compared with the same processing applied to a narrow-band tone burst wave packet. Processing of the chirped signal permits easy separation of overlapped return echoes which could not be resolved when narrow-band signals were used. Finally, by compressing the energy within a chirped signal to a single detection spike, an apparent 15-fold enhancement in signal-to-noise ratio is observed.
Changes of voice parameters and melody patterns during the first year of life in human twins
Authors: Wermke Kathleen , Mende Werner , Borschberg Hanno , Ruppert Roland
Published: July 2002

The study analyzed changes of cry characteristics of twins using spectrograms, fundamental frequency contours (melody), and several indicators of microvariability of the fundamental frequency (F0) calculated with the aid of a KAY Elemetrics CSL Model 4305. Subjects were 15 identical and 15 fraternal healthy twin pairs, whose spontaneous utterances were recorded every 6 weeks over the first year of life. Developmental changes of F0, jitter, perturbation quotient, degree of voiceless, degree of subharmonic components as well as the evolution of complex melody patterns were analyzed. Correlations of the voice data with anthropometric data (weight, length, head circumference) and obstetrical factors (time of gestation, presentation, birth modus) were calculated to consider influences by growth discordance or different birth histories. As identical twins have a much greater congenital synchronization of development, universals of prespeech evolution are more convincingly expressed in these pairs (lower intrapair differences). A statistically significant higher intrapair concordance in identical twins was found for the mean F0 within the first week of life, for the mean F0 and jitter in the period within 5–8 months of life, and for certain melody patterns. For other parameters, significant intrapair differences between identical and fraternal twins were not found.
A cognitive approach of urban soundscapes
Authors: Dubois Daniele , David Sophie
Published: July 2002

The presented cognitive approach of noises in urban environments focuses on meaning and as such integrates linguistic, psychological, and acoustic conceptualizations and methodologies. It deals with the acoustic phenomena that are perceived, conceived, and said as relevant by the subjects. The productivity of this approach has been evaluated in two research programs. Experiments combining linguistic and psychological analyses showed that urban soundscapes include a complex combination of unpleasant and pleasant noises. The identity of the source and the temporal and spatial contexts of occurrence of the noises are present in subjects’ cognitive representation and influence their perception. Experiments on alarm signals showed that contextual contraints influence the perceptual thresholds of the signals, their identification, and their efficiency (contrasting signals as such with nonmeaningful noises). In conclusion, such a ‘‘situated’’ cognitive (and pluridisciplinary) approach allows (i) at a theoretical level, to identify the roles of top down (high level) constraints on low-level perceptual processing and (ii) at a methodological level, it suggests to first design procedures to identify the meaningful categories of sounds and their properties at linguistic and psychological levels before describing them in physical dimensions and experimentally manipulating them in psychophysical paradigms.
Transient normal stress response in a concentrated suspension of spherical particles
Authors: Kolli Venkata Giri , Pollauf Emily J. , Gadala-Maria Francis
Published: July 2002

The transient normal force response in a concentrated suspension of spherical particles upon startup of shear, following a period of rest, was found to depend on the direction in which shear was restarted. When shear was restarted in the same direction, the normal force signal rapidly grew to its positive steady-state value. However, when shear was restarted in the opposite direction, the normal force signal was initially negative and decreased, within the response time of the instrument, to a negative minimum, from which it gradually increased, passing through zero, to its positive steady-state value. This is believed to be the first experimental confirmation of this phenomenon, which had been suggested by the numerical simulations of previous investigators.
Particles in Tube Flow at Moderate Reynolds Number
Authors: McMahon Thomas A. , Parker Ronald R.
Published: July 2002

Studies were made of neutrally buoyant suspensions of solid particles in steady flow through tubes. Microwave Doppler flowmeter techniques made it possible to investigate the moderate Reynolds numbers and high particle concentrations appropriate to many biological and industrial applications. The tubular pinch effect and the development of partial plug flow were observed independently at low concentrations and low Reynolds numbers, respectively. Both effects occurred together at simultaneously high concentrations and Reynolds numbers. For a given flow condition, the fraction of the tube consolidated in plug flow increases as either concentration or Reynolds number is increased.
Steady-shear viscosity of stirred yogurts with varying ropiness
Authors: van Marle M. E. , van den Ende D. , de Kruif C. G. , Mellema J.
Published: July 2002

Stirred yogurt was viewed as a concentrated dispersion of aggregates consisting of protein particles. The steady-shear behavior of three types of stirred yogurt with varying ropiness was investigated experimentally. To describe the shear-dependent viscosity, a microrheological model was used which was developed for weakly aggregating dispersions. This model was capable of successfully describing the steady-state viscosity as a function of shear rate of the stirred yogurts, the protein concentration of which ranged between 2.0% and 3.9%. The value of the fractal dimensionality df, following from the model for the aggregates is about 2.24, which was similar to the value of df found with other methods. Moreover, realistic values were found for the interaction forces (energies) describing interaction between the aggregates. The calculated size of the aggregates was close to the size found before by applying different experimental techniques. Using this model, the interpretation of the measured curves suggests that the exopolysaccharides, produced by the lactic acid bacteria in yogurt, play a significant role in the rheology of stirred yogurt.
Clinical Trial Diversity—Will We Know It When We See It?
Authors: Varma Tanvee , Gross Cary P. , Miller Jennifer E.
Published: April 2023

This Editorial discusses the existing policy efforts in the US for ensuring adequate racial and ethnic diversity in clinical trials, identifies barriers to consistency and acceptable representation, and suggests measures to address them.
LRRK2 and Parkinson's disease: from genetics to targeted therapy
Authors: Sosero Yuri L. , Gan‐Or Ziv
Published: April 2023

LRRK2 variants are implicated in both familial and sporadic PD. LRRK2‐PD has a generally benign clinical presentation and variable pathology, with inconsistent presence of Lewy bodies and marked Alzheimer's disease pathology. The mechanisms underlying LRRK2‐PD are still unclear, but inflammation, vesicle trafficking, lysosomal homeostasis, and ciliogenesis have been suggested, among others. As novel therapies targeting LRRK2 are under development, understanding the role and function of LRRK2 in PD is becoming increasingly important. Here, we outline the epidemiological, pathophysiological, and clinical features of LRRK2‐PD, and discuss the arising therapeutic approaches targeting LRRK2 and possible future directions for research.
Transcytosis Mediated Deep Tumor Penetration for Enhanced Chemotherapy and Immune Activation of Pancreatic Cancer
Authors: Chen Hongyi , Song Haolin , Luo Yifan , Li Chufeng , Wang Yu , Liu Jie , Luo Feifei , Fan Hongrui , Li Xuwen , Sun Tao , Jiang Chen
Published: April 2023

The hyperproliferative tumor stroma of pancreatic ductal adenocarcinoma (PDAC) severely limits drug permeation and constructs an immunosuppressive microenvironment, causing resistance to chemotherapy and immunotherapy. Traditional nanomedicine mainly focuses on manipulating nanoparticles’ particle size or electrical characteristics to penetrate deep PDAC through the paracellular pathway, but the transcellular pathway is often ignored. Therefore, a versatile drug‐polymer conjugate PODEA‐Gem‐HMI is prepared and assembled into nanoparticles for the codelivery of chemotherapy drug gemcitabine and focal adhesion kinase (FAK) inhibitor defactinib. While sensing the mild acidity in the tumor microenvironment, the nanoparticle will disintegrate and release defactinib to modulate the tumor stroma. The PODEA block of the conjugate can bind with cell membranes reversibly and trigger adsorption‐mediated transcytosis (AMT) for promoted tumor penetration and cellular uptake. The internalized conjugates will release gemcitabine responding to the overexpressed glutathione (GSH) for enhanced chemotherapy, and PHMI can condensate the STING monomers for prolonged spontaneous immune stimulation.
Symmetry‐Mismatch‐Induced Ferromagnetism in the Interfacial Layers of CaRuO3/SrTiO3 Superlattices
Authors: Shi Wenxiao , Zhang Jine , Chen Xiaobing , Zhang Qinghua , Zhan Xiaozhi , Li Zhe , Zheng Jie , Wang Mengqin , Han Furong , Zhang Hui , Gu Lin , Zhu Tao , Liu Banggui , Chen Yunzhong , Hu Fengxia , Shen Baogen , Chen Yuansha , Sun Jirong
Published: April 2023

By modifying the entangled multi‐degrees of freedom of transition‐metal oxides, interlayer coupling usually produces interfacial phases with unusual functionalities. Herein, a symmetry‐mismatch‐driven interfacial phase transition from paramagnetic to ferromagnetic state is reported. By constructing superlattices using CaRuO3 and SrTiO3, two oxides with different oxygen octahedron networks, the tilting/rotation of oxygen octahedra near interface is tuned dramatically, causing an angle increase from ≈150° to ≈165° for the RuORu bond. This in turn drives the interfacial layer of CaRuO3, ≈3 unit cells in thickness, from paramagnetic into ferromagnetic state. The ferromagnetic order is robust, showing the highest Curie temperature of ≈120 K and the largest saturation magnetization of ≈0.7 µB per formula unit. Density functional theory calculations show that the reduced tilting/rotation of RuO6 octahedra favors an itinerant ferromagnetic ground state. This work demonstrates an effective phase tuning by coupled octahedral rotations, offering a new approach to explore emergent materials with desired functionalities.
Across‐Layer Sliding Ferroelectricity in 2D Heterolayers
Authors: Yang Liu , Wu Menghao
Published: April 2023

Although the monolayers of most 2D materials are non‐ferroelectric with highly symmetric lattices, symmetry breaking may take place in their bilayers upon some stacking configuration, giving rise to so‐called sliding ferroelectricity where the vertical polarizations can be electrically reversed via interlayer translation. However, it is not supposed to appear in systems like graphene bilayer with centro‐symmetry at any stacking configuration, and the origin of the recently reported ferroelectricity (Nature 2020, 588, 71) in graphene bilayer intercalated between h‐BN remains mysterious. Here, a type of across‐layer sliding ferroelectricity that arises from the asymmetry of next‐neighbor interlayer couplings is proposed. The first‐principles evidence is shown that the vertical polarizations in intercalated centro‐symmetric 2D materials like graphene bilayer can be switched via multilayer sliding, which is likely to be the origin of the observed ferroelectric hysteresis. Moreover, such ferroelectricity may exist in a series of other heterolayers with quasi‐degenerate polar states, like graphene bilayer or trilayer on BN substrate, or even with a molecule layer on surface where each molecule can store 1‐bit data independently, resolving the bottleneck issue of sliding ferroelectricity for high‐density data storage.
D–A Structured High‐Performance Photothermal/Photodynamic Thionin‐Synthetic Melanin Nanoparticles for Rapid Bactericidal and Wound Healing Effects
Authors: Liu Wenjing , Yu Yuanyuan , Cheng Wei , Wang Xinyue , Zhou Man , Xu Bo , Wang Ping , Wang Qiang
Published: April 2023

Synthesized melanin nanoparticles (SMNPs) are used as advanced photothermal materials. However, their internal structures are complex and disordered, and tuning the photothermal performance of nanoparticles is still a hot spot of concern. This article presents thionin (Th)‐doped SMNPs, namely Th‐SMNPs, which are the first SMNPs formed using the one‐pot polymerization of Th with Levodopa. Th can undergo Michael addition and Schiff base reaction between indole dihydroxy/indolequinone and their oligomers to form donor–acceptor pairs in the structure to modulate the photothermal performance of SMNPs. Structural and spectroscopic analyses and density functional theory simulations further confirm the existence of the donor–acceptor structure. Th‐SMNPs exhibit excellent total photothermal efficiency (34.49%) in the near‐infrared region (808 nm), which is a 60% improvement compared to SMNPs. This allows Th‐SMNPs to exhibit excellent photothermal performance at low power 808 nm laser irradiation. Meanwhile, Th not only enhances the photothermal properties of SMNPs, but also imparts photodynamic effects to SMNPs. Th‐SMNPs can produce 1O2 under 660 nm laser irradiation. A dual‐function photothermal and photodynamic textile named Th‐SMNPs@cotton is constructed based on Th‐SMNPs, which can act as a rapid photothermal/photodynamic sterilization and is promising for wound healing treatment of bacterial infections under low‐power dual laser irradiation.
Multi‐Scale Structure Engineering of ZnSnO3 for Ultra‐Long‐Life Aqueous Zinc‐Metal Batteries
Authors: Ling Fangxin , Wang Lifeng , Liu Fanfan , Ma Mingze , Zhang Shipeng , Rui Xianhong , Shao Yu , Yang Yaxiong , He Shengnan , Pan Hongge , Wu Xiaojun , Yao Yu , Yu Yan
Published: April 2023

Suppressing the severe water‐induced side reactions and uncontrolled dendrite growth of zinc (Zn) metal anodes is crucial for aqueous Zn‐metal batteries to achieve ultra‐long cyclic lifespans and promote their practical applications. Herein, a concept of multi‐scale (electronic‐crystal‐geometric) structure design is proposed to precisely construct the hollow amorphous ZnSnO3 cubes (HZTO) for optimizing Zn metal anodes. In situ gas chromatography demonstrates that Zn anodes modified by HZTO (HZTO@Zn) can effectively inhibit the undesired hydrogen evolution. The pH stabilization and corrosion suppression mechanisms are revealed via operando pH detection and in situ Raman analysis. Moreover, comprehensive experimental and theoretical results prove that the amorphous structure and hollow architecture endow the protective HZTO layer with strong Zn affinity and rapid Zn2+ diffusion, which are beneficial for achieving the ideal dendrite‐free Zn anode. Accordingly, excellent electrochemical performances for the HZTO@Zn symmetric battery (6900 h at 2 mA cm−2, 100 times longer than that of bare Zn), HZTO@Zn||V2O5 full battery (99.3% capacity retention after 1100 cycles), and HZTO@Zn||V2O5 pouch cell (120.6 Wh kg−1 at 1 A g−1) are achieved. This work with multi‐scale structure design provides significant guidance to rationally develop advanced protective layers for other ultra‐long‐life metal batteries.
Stabilization of FAPbI3 with Multifunctional Alkali‐Functionalized Polymer
Authors: Zhao Chenxu , Zhang Hong , Almalki Masaud , Xu Jia , Krishna Anurag , Eickemeyer Felix T. , Gao Jing , Wu Yu Mao , Zakeeruddin Shaik M. , Chu Junhao , Yao Jianxi , Grätzel Michael
Published: April 2023

The defects located at the interfaces and grain boundaries (GBs) of perovskite films are detrimental to the photovoltaic performance and stability of perovskite solar cells. Manipulating the perovskite crystallization process and tailoring the interfaces with molecular passivators are the main effective strategies to mitigate performance loss and instability. Herein, a new strategy is reported to manipulate the crystallization process of FAPbI3‐rich perovskite by incorporating a small amount of alkali‐functionalized polymers into the antisolvent solution. The synergic effects of the alkali cations and poly(acrylic acid) anion effectively passivate the defects on the surface and GBs of perovskite films. As a result, the rubidium (Rb)‐functionalized poly(acrylic acid) significantly improves the power conversion efficiency of FAPbI3 perovskite solar cells to approaching 25% and reduces the risk of lead ion (Pb2+) leakage continuously via the strong interaction between CO bonds and Pb2+. In addition, the unencapsulated device shows enhanced operational stability, retaining 80% of its initial efficiency after 500 h operation at maximum power point under one‐sun illumination.
Continuous Room‐Temperature Spin‐Injection Modulation Achieved by Spin‐Filtering Competition in Molecular Spin Valves
Authors: Hu Shunhua , Liu Wei , Guo Lidan , Zhang Rui , Gu Xianrong , Meng Ke , Qin Yang , Guo Ankang , Yang Tingting , Zhang Cheng , Yang Xueli , Lu Shuhang , Wu Meng , Lu Kun , Tan Ting , Zhou Erjun , Wei Zhixiang , Sun Xiangnan
Published: April 2023

Abundant spin‐related phenomena that originate from interfaces between ferromagnetic electrodes and molecular semiconductors have greatly enriched research in spintronics, and they are considered promising for realizing novel spintronic functionalities in the future. However, despite great effort, the interfacial effect cannot be precisely controlled to achieve steady and predictable functions, especially at room temperature, and this has gradually become a significant bottleneck in the development of molecular spintronics. In this study, an innovative spin‐filtering‐competition mechanism is proposed to continuously modulate the interfacial effect in molecular spin valves at room temperature. To form this novel mechanism, the original spin‐filtering effect from pure cobalt competes with the newly generated one, which is induced by the bonding effect between cobalt and lithium fluoride. Subsequently, by precisely controlling competition through lithium fluoride coverage on the cobalt surface, continuous modulation of the spin‐injection process can be successfully achieved at room temperature. Spin polarization of the injected current and magnetoresistance effect can be actively controlled or their sign can be completely reversed through this novel mechanism. This study provides an innovative approach and theory for precisely controlling spin‐related interfacial effects, which may further promote the scientific and technological development of spintronics.
Rationalized Electroepitaxy toward Scalable Single‐Crystal Zn Anodes
Authors: Su Yiwen , Chen Buhang , Sun Yingjie , Xue Zaikun , Zou Yuhan , Yang Dongzi , Sun Luzhao , Yang Xianzhong , Li Chao , Yang Yujia , Song Xiuju , Guo Wenyi , Dou Shixue , Chao Dongliang , Liu Zhongfan , Sun Jingyu
Published: April 2023

Electroepitaxy is recognized as an effective approach to prepare metal electrodes with nearly complete reversibility. Nevertheless, large‐scale manipulation is still not attainable owing to complicated interfacial chemistry. Here, the feasibility of extending Zn electroepitaxy toward the bulk phase over a mass‐produced mono‐oriented Cu(111) foil is demonstrated. Interfacial Cu–Zn alloy and turbulent electroosmosis are circumvented by adopting a potentiostatic electrodeposition protocol. The as‐prepared Zn single‐crystalline anode enables stable cycling of symmetric cells at a stringent current density of 50.0 mA cm−2. The assembled full cell further sustaines a capacity retention of 95.7% at 5.0 A g−1 for 1500 cycles, accompanied by a controllably low N/P ratio of 7.5. In addition to Zn, Ni electroepitaxy can be realized by using the same approach. This study may inspire rational exploration of the design of high‐end metal electrodes.
Exploring Electronic Characteristics of Acceptor–Donor–Acceptor‐Type Molecules by Single‐Molecule Charge Transport
Authors: Li Peihui , Xiong Wan , Wang Jinying , Hao Jie , Li Mingpeng , Wang Boyu , Chen Yijian , Si Wei , Ren Haiyang , Li Guangwu , Chen Yongsheng , Lü Jingtao , Zhang Hongtao , Jia Chuancheng , Guo Xuefeng
Published: April 2023

The electronic characteristics of organic optoelectronic materials determine the performance of corresponding devices. Clarifying the relationship between molecular structure and electronic characteristics at the single‐molecule level can help to achieve high performance for organic optoelectronic materials and devices, especially for organic photovoltaics. In this work, a typical acceptor–donor–acceptor (A–D–A)‐type molecule is explored by combining theoretical and experimental studies to reveal the intrinsic electronic characteristics at the single‐molecule level. Specifically, the A–D–A‐type molecule with 1,1‐dicyano methylene‐3‐indanone (INCN) acceptor units exhibits an enhanced conductance in single‐molecule junctions when compared with the control donor molecule, because the acceptor units of the A–D–A‐type molecule contribute additional transport channels. In addition, through opening the S∙∙∙O noncovalent conformational lock by protonation to expose the −S anchoring sites, the charge transport of the D central part is detected, proving that the conductive orbitals contributed by the INCN acceptor groups can penetrate the whole A–D–A molecule. These results provide important insights into the development of high‐performance organic optoelectronic materials and devices toward practical applications.
Non‐Toxic CuInS2/ZnS Colloidal Quantum Dots for Near‐Infrared Light‐Emitting Diodes
Authors: Lim Li Jun , Zhao Xiaofei , Tan Zhi‐Kuang
Published: April 2023

Ternary CuInS2 quantum dots (QDs) with photoluminescence that is tunable from the visible to the near‐infrared (NIR) region are promising light‐emitters for consumer electronics due to the absence of toxic elements such as Pb, Cd, or As. Despite the compelling performance of visible‐light‐emitting CuInS2 QDs, reports on NIR emission remain limited, with modest efficiencies at wavelengths beyond 900 nm. In this work, the facile synthesis of NIR‐emitting CuInS2/ZnS QDs is reported. A combination of two sulfur precursors w as used in the synthesis, comprising 1‐dodecanethiol (DDT) and hexamethyldisilathiane (HMDS). The reactive HMDS facilitates faster nucleation and leads to a higher density of emissive Cu‐deficiency sites. The resulting QDs exhibit high photoluminescence quantum efficiency (PLQE) of 65% at a long emission wavelength of 920 nm. Using these QDs, NIR light‐emitting diodes (LED) are fabricated, which attain an external quantum efficiency (EQE) of 8.2%. This efficiency is comparable to the best reported PbS and InAs QD LEDs, and the emission wavelength exceeds that of lead iodide perovskites. This work thus marks one of the first reports of efficient NIR LEDs based on environmentally benign CuInS2 QDs and may open up promising new applications in consumer electronic products.
Top Electrode Engineering for High‐Performance Ferroelectric Hf0.5Zr0.5O2 Capacitors
Authors: Kim Beom Yong , Lee In Soo , Park Hyeon Woo , Lee Yong Bin , Lee Suk Hyun , Oh Minsik , Ryoo Seung Kyu , Byun Seung Ryong , Kim Kyung Do , Lee Jae Hoon , Cho Deok‐Yong , Park Min Hyuk , Hwang Cheol Seong
Published: April 2023

This work systematically studies the TiN, Ru, and RuO2 top electrodes (TEs) effects on the ferroelectric properties of Hf0.5Zr0.5O2 (HZO) films. The Ru top electrode significantly improves the ferroelectric performance even with the conventional TiN bottom electrode. The high two‐remanent polarization (2Pr) value (≈65 µC cm−2) is obtained with the capacitor with Ru TE, which is ≈1.5 times higher than that of the capacitors with the TiN and RuO2 TEs. Moreover, it does not break down to 1 × 109 cycling with a high cycling electric field of 4.0 MV cm−1, while others do lower cycle numbers. Further enhancement can be achieved by inserting a 2‐nm‐thick HfON interfacial layer between the HZO film and TiN bottom electrode while keeping the Ru/HZO top interface structure. The capacitor does not break down even at an electric field strength of 4.8 MV cm−1, at which a 2Pr value of ≈67 µC cm−2 is achieved. Furthermore, it can endure 1 × 1011 switching cycles while a 2Pr value of 45–53 µC cm−2 is retained. Therefore, this study elucidates that interfacial engineering is an important technology that can overcome the trade‐off relationship between Pr and endurance, a critical issue in ferroelectric doped HfO2‐based films.
Do Australians trust scientists? It depends on the ‘science’
Authors: Tranter Bruce
Published: April 2023

Trust in science and scientists underlies public support for social and environmental issues, from taking action on climate change to preventing the spread of viruses. Nationally representative Australian survey data show that public trust in university research is higher than that conducted in other institutions. As sources of information, public trust in scientists is considered across potentially polarising and relatively uncontroversial fields of science, with trust varying considerably according to the type of science examined. Public trust is highest in vaccine science and weather forecasting, and lowest for GM crop science, while climate science and forest management fall in between. Social and political background variables are important correlates of trust in science. Younger, tertiary educated, politically progressive Australians are most trusting. Greens party identifiers and environmentalists are more likely than other respondents to trust all types of science examined here—including GM crop science—while institutional trust is positively associated with trust in scientists.