bluuebunny/crossref_metadata_2025_split huggingface dataset:
DMD maskless digital lithography based on stepwise rotary stitching
Authors: Yuan Qixiang , Liu Chunxia , Huang Long , Zhao Shaoqing , Wang Zhengxiao , Zhang Han , Liu Minzhe , Jia Zhongqing , Zhai Ruizhan , Lu Zifeng , Liu Hua 
Published: February 2023

Abstract
Diffractive optical elements (DOEs) with rotationally symmetric phase distribution are mainly produced by laser direct writing technique in a polar coordinate system, which has slow processing speed and limited fabrication area. In this paper, we propose a digital micro-mirror device maskless digital lithography technique based on stepwise rotary stitching. DOEs with rotationally symmetric phase distribution are fabricated by exposure of stitching units and rotation of rotary tables. Then, different stitching units are designed to compensate for the errors caused by the accuracy of the rotary table. Finally, the high quality DOEs are produced by the double-exposure method. When increasing the fabrication area, significantly improves the saw-tooth of the lithography pattern edge while reducing misalignment and overlap of stitching caused by residual errors. The diameter of the fabricated Fresnel zone plate was increased from 5.25 mm to 11.40 mm, and the fabrication area was 4.72 times larger than conventional lithography. The stitching error of 18.95 μm has been eliminated after optimization, and the pixelization has been smoothed. The diffraction results show that the method not only can produce large area and high-quality diffraction elements but also greatly reduce the processing cost.
The effect of DRIE notching on field emission enhanced breakdown in SOI based MEMS electrodes
Authors: Zhang Xuan , Qiao Dayong , Zhu Yao 
Published: February 2023

Abstract
Microscale (<5 μm) gas breakdown is usually dominated by field emission, which is influenced largely by electrode surface morphology. At present, there is a large number of studies on the breakdown and discharge of different metal electrode geometry and electrode spacing as well as micro-electro-mechanical system (MEMS) device structures, but few studies on the breakdown of MEMS electrodes affected by notching, which will greatly change the electrode surface morphology but is difficult to completely avoid in deep reactive ion etching process based on silicon on insulator (SOI) wafer. In response to this situation, this paper conducted breakdown tests and field emission tests on MEMS samples with and without notching. It was found that samples with notching could withstand more breakdowns of about 6–13 times before the formation of internal resistance, increased by 200%–300% compared with samples without notching, and have a lower breakdown voltage of about 210 V, 16% lower than that of samples without notching. In addition, it was also found that for the samples with notching, the field enhancement factor gradually decreases with the increase of the number of breakdown events. When the field enhancement factor decreases to about 100, the subsequent breakdown is highly likely to cause the sample to form electrical connection, thus completely damaging the sample. Above conclusions have certain reference value for designing the actuation voltage of MEMS devices based on SOI wafers.
Influence of magnetic relaxation on magnetoelastic resonance-based detection
Authors: Sisniega B , Gutiérrez J , Barandiaran J M , Porro J M , García-Arribas A 
Published: February 2023

Abstract
The phenomenon of magnetic relaxation in amorphous ferromagnetic alloys can result in an undesired time evolution of the magnetization that produces serious drawbacks in the use of these materials in sensor applications. The present work studies, at room temperature, the influence of magnetic relaxation on the performance of an amorphous ferromagnetic ribbon as the main element of a magnetoelastic resonance (MER)-based sensor. The time evolution was observed through the evolution of the MER signal, in particular through the variation experienced by the resonance frequency

f

r

, which is the main parameter used for sensing. It is found that, after the bias field is changed to a given value, and under constant excitation conditions,

f

r

increases with time in a typical relaxation behavior with a relaxation amplitude

Δ

f

r

and a relaxation time

τ

that depend on the excitation conditions. The amplitude of the excitation h turned out to be a key factor on the relaxation, since larger excitation field amplitudes (h

⩾
100

mOe) result in a considerable decrease of relaxation times (

τ
<
460

s

)

and a reduction of the variation of the resonance frequency (

Δ

f

r

<
77

Hz

). The influence of this relaxation on the sensor performance and the possible approaches to overcome this problem are evaluated and applied to the case of a magnetoelastic sensor, operating as mass sensor, for monitoring a chemical precipitation reaction.
Dynamics of recombination in viscous electron–hole plasma in a mesoscopic GaAs channel
Authors: Pusep Yu A , Teodoro M D , T Patricio M A , M Jacobsen G , Gusev G M , Levin A D , Bakarov A K 
Published: February 2023

Abstract
The recombination dynamics are studied in viscous electron–hole plasma, consisting of electrons and photo-generated heavy and light holes, formed in the high-mobility mesoscopic GaAs channel. It is shown that an increase in the pump power reduces the concentration and mobility of background electrons, which, in turn, slows down their recombination with photogenerated holes. At a critical pump power, the recombination time begins to decrease, which is a consequence of the transition of a viscous electron–hole plasma from the hydrodynamic regime to the Drude diffusive regime. The observed transition occurs when the scattering of electrons with disorder begins to dominate over electron–electron scattering, which leads to the transformation of an inhomogeneous Poiseuille charge flow into a homogeneous diffusion flow. As a result, an optical analogue of the Gurzhi effect has been found.
Engineering Pt/Co/AlO
x
heterostructures to enhance the Dzyaloshinskii–Moriya interaction
Authors: Sankhi Babu R , Echeverria Elena M , Mandal Soumya , Annaorazov Muhammet , Sachan Ritesh , Mcllroy David N , Meyers Derek , Turgut Emrah 
Published: February 2023

Abstract
The study of interfacial Dzyaloshinskii–Moriya interaction (DMI) in perpendicularly magnetized structurally asymmetric heavy metal/ferromagnet multilayer systems is of high importance due to the formation of chiral magnetic textures in the presence of DMI. Here, we report the impact of cobalt oxidation at the Co/AlO
x
interface in Pt/Co/AlO
x
trilayer structures on the DMI by varying the post-growth annealing time, Al thickness and substrate. To quantify DMI we employed magneto-optical imaging of the asymmetric domain wall expansion, hysteresis loop shift, and spin-wave spectroscopy techniques. We further correlated the Co oxidation with low-temperature Hall effect measurements and x-ray photoelectron spectroscopy. Our results emphasize the importance of full characterization of the magnetic films that could be used for magnetic random access memory technologies when subjected to the semiconductor temperature processing conditions, as the magnetic interactions are critical for device performance and can be highly sensitive to oxidation and other effects.
Non-self-similar grain growth by zero-temperature Potts model
Authors: Zöllner D 
Published: February 2023

Abstract
Self-similar coarsening, a well-researched aspect of normal grain growth, is a key component of grain growth theories and visible in mesoscopic simulations of ideal grain growth. One particular simulation algorithm is the Potts model, which can be used to perform a thorough investigation of the temporal evolution of polycrystalline microstructures. Used with carefully selected parameters, the Potts model recreates normal grain growth quite accurately. One specific feature necessary to reach this goal is the simulation temperature, i.e. simulation thermal energy. It prevents grain boundaries from aligning along the underlying simulation lattice. Nevertheless, there are still today many researchers who implement classical zero-temperature Potts model simulations—often for reasons of simplification and/or modeling speed. In the current study, we show in detail the negative effect of setting the simulation temperature to zero. As a result, a unique type of non-self-similar coarsening is observed, where, e.g. the von Neumann–Mullins-relation shows unexpected time-dependent behavior. Hence, this study can be understood as a blueprint on why not to use a zero-temperature Potts model.
Cellulose nanocrystal functionalized aramid nanofiber reinforced epoxy nanocomposites with high strength and toughness
Authors: Jung Jaehyun , Sodano Henry A 
Published: February 2023

Abstract
The mechanical properties of polymer nanocomposites can be improved by incorporating various types of nanofillers. The hybridization of nanofillers through covalent linkages between nanofillers with different dimensions and morphology can further increase the properties of nanocomposites. In this work, aramid nanofibers (ANFs) are modified using chlorinated cellulose nanocrystals (CNCs) and functionalized with 3-glycidoxypropyltrimethoxysilane to improve the chemical and mechanical interaction in an epoxy matrix. The integration of CNC functionalized ANFs (fACs) in the epoxy matrix simultaneously improves Young’s modulus, tensile strength, fracture properties, and viscoelastic properties. The test results show that 1.5 wt% fAC reinforced epoxy nanocomposites improve Young’s modulus and tensile strength by 15.1% and 10.1%, respectively, and also exhibit 2.5 times higher fracture toughness compared to the reference epoxy resin. Moreover, the glass transition temperature and storage modulus are found to increase when fACs are incorporated. Thus, this study demonstrates that the enhanced chemical and mechanical interaction by the CNC functionalization on the ANFs can further improve the static and dynamic mechanical properties of polymer nanocomposites.
Design and characteristic analysis of flexible CNT film patch for potential application in ultrasonic therapy
Authors: Feng Yanxia , Zhang Qilin , Li Houyang , Qi Qianshou , Tong Zhenzhen , Rong Dalun , Zhou Zhenhuan 
Published: February 2023

Abstract
Ultrasonic therapy has drawn increasing attention due to its noninvasiveness, great sensitivity and strong penetration capabilities. However, most of traditional rigid ultrasonic probes cannot achieve a solid interfacial contact with irregular nonplanar surfaces, which leads to unstable therapeutic effects and limitations of widespread use in practical applications. In this paper, a new flexible ultrasonic patch based on carbon nanotube (CNT) films is designed and fabricated to achieve a potential application in ultrasonic therapy. This patch is composed of a CNT film, a thermal protective layer and a heat sinking layer, and has the advantages of simple structure, soft, ultrathin and completely conforming to the treatment area. Theoretical and experimental studies are performed to investigate the acoustic and temperature fields before and after deformation. Effects of key design parameters of the patch on acoustic performances and temperature distributions are revealed. Numerical results indicate that the CNT film patch can produce ultrasounds over a wide frequency range and temperatures under the threshold of burn injury whether it is bent or not. Furthermore, it is also noted that the sound waves emitted from the bending patch are focused at the center of the bending patch, which demonstrates that the target treatment area can be controlled.
Mesoscopic 2D molecular self-assembly on an insulator
Authors: Kumar Dhaneesh , Hellerstedt Jack , Lowe Benjamin , Schiffrin Agustin 
Published: February 2023

Abstract
Two-dimensional (2D) nanostructures and nanomaterials offer potential for a wide range of technological applications in electronics, optoelectronics, data storage, sensing and catalysis. On-surface molecular self-assembly – where organic molecules act as building blocks and where surfaces play the role of supporting templates – allows for the bottom-up synthesis of such 2D systems with tuneable atomically precise morphologies and tailored electronic properties. These self-assembly protocols are well established on metal surfaces, but remain limited on electronically gapped substrates (insulators, semiconductors). The latter are useful for preventing electronic coupling (that is, hybridization between molecular assembly and underlying surface) and for avoiding quenching of optical processes, necessary for prospective electronic and optoelectronic applications. In particular, molecular self-assembly on surfaces other than weakly interacting metals can be challenging due to substrate reactivity, defects and inhomogeneities, resulting in intricate energy landscapes that limit the growth kinetically and hampers the synthesis of large-area defect-free 2D systems. Here, we demonstrate the self-assembly of a 2D, atomically thin organic molecular film on a model wide bandgap 2D insulator, single-layer hexagonal boron nitride (hBN) on Cu(111). The molecular film consists of flat, aromatic 9,10-di-cyano-anthracene (DCA) molecules. Our low-temperature scanning tunnelling microscopy and spectroscopy measurements revealed mesoscopic (> 100 x 100 nm^2), topographically homogeneous crystalline molecular domains resulting from flat molecular adsorption and noncovalent in-plane cyano-ring bonding, with electronically decoupled molecular orbitals (MOs) lying within the hBN electronic gap. These MOs exhibit an energy level spatial modulation (~300 meV) that follows the moiré work function variation of hBN on Cu(111). This work paves the way for large-area, atomically precise, highly crystalline 2D organic (and metal-organic) nanomaterials on electronically functional wide bandgap insulators.
Deep learning based unpaired image-to-image translation applications for medical physics: a systematic review
Authors: Chen Junhua , Chen Shenlun , Wee Leonard , Dekker Andre , Bermejo Inigo 
Published: February 2023

AbstractPurpose. There is a growing number of publications on the application of unpaired image-to-image (I2I) translation in medical imaging. However, a systematic review covering the current state of this topic for medical physicists is lacking. The aim of this article is to provide a comprehensive review of current challenges and opportunities for medical physicists and engineers to apply I2I translation in practice.Methods and materials. The PubMed electronic database was searched using terms referring to unpaired (unsupervised), I2I translation, and medical imaging. This review has been reported in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. From each full-text article, we extracted information extracted regarding technical and clinical applications of methods, Transparent Reporting for Individual Prognosis Or Diagnosis (TRIPOD) study type, performance of algorithm and accessibility of source code and pre-trained models.Results. Among 461 unique records, 55 full-text articles were included in the review. The major technical applications described in the selected literature are segmentation (26 studies), unpaired domain adaptation (18 studies), and denoising (8 studies). In terms of clinical applications, unpaired I2I translation has been used for automatic contouring of regions of interest in MRI, CT, x-ray and ultrasound images, fast MRI or low dose CT imaging, CT or MRI only based radiotherapy planning, etc Only 5 studies validated their models using an independent test set and none were externally validated by independent researchers. Finally, 12 articles published their source code and only one study published their pre-trained models.Conclusion. I2I translation of medical images offers a range of valuable applications for medical physicists. However, the scarcity of external validation studies of I2I models and the shortage of publicly available pre-trained models limits the immediate applicability of the proposed methods in practice.
Novel framework for determining TPS-calculated doses corresponding to detector locations using 3D camera in in vivo surface dosimetry
Authors: Sheen Heesoon , Park Ye-in , Cho Min-Seok , Son Junyoung , Shin Han-Back , Han Min Cheol , Kim Hojin , Lee Ho , Kim Dong Wook , Kim Jin Sung , Hong Chae-Seon 
Published: February 2023

Abstract

Purpose. To address the shortcomings of current procedures for evaluating the measured-to-planned dose agreement in in vivo dosimetry (IVD), this study aimed to develop an accurate and efficient novel framework to identify the detector location placed on a patient’s skin surface using a 3D camera and determine the planned dose at the same anatomical position corresponding to the detector location. Methods. Breast cancer treatment was simulated using an anthropomorphic adult female phantom (ATOM 702D; CIRS, Norfolk, VA, USA). An optically stimulated luminescent dosimeter was used for surface dose measurements (MyOSLchip, RadPro International GmbH, Germany) at six IVD points. Three-dimensional surface imaging (3DSI) of the phantom with the detector was performed in the treatment position using a 3D camera. The developed framework, iSMART, was designed to import 3DSI and treatment planning data for determining the position of the IVD detectors in the 3D treatment planning DICOM image. The clinical usefulness of iSMART was evaluated in terms of accuracy and efficiency, for comparison with the results obtained using cone-beam computed tomography (CBCT) image guidance. Results. The relative dose difference between the planned doses determined using iSMART and CBCT images displayed similar accuracies (within approximately ±2.0%) at all detector locations. The relative dose differences between the planned and measured doses at the six detector locations ranged from –4.8% to 3.1% for the CBCT images and –3.5% to 2.1% for iSMART. The total time required to read the planned doses at six detector locations averaged at 8.1 and 0.8 min for the CBCT images and iSMART, respectively. Conclusions. The proposed framework can improve the robustness of IVD analyses and aid in accurate and efficient evaluations of the measured-to-planned dose agreement.
Full waveform inversion for arterial viscoelasticity
Authors: Roy Tuhin , Guddati Murthy N 
Published: February 2023

Abstract

Objective. Arterial viscosity is emerging as an important biomarker, in addition to the widely used arterial elasticity. This paper presents an approach to estimate arterial viscoelasticity using shear wave elastography (SWE). Approach. While dispersion characteristics are often used to estimate elasticity from SWE data, they are not sufficiently sensitive to viscosity. Driven by this, we develop a full waveform inversion (FWI) methodology, based on directly matching predicted and measured wall velocity in space and time, to simultaneously estimate both elasticity and viscosity. Specifically, we propose to minimize an objective function capturing the correlation between measured and predicted responses of the anterior wall of the artery. Results. The objective function is shown to be well-behaving (generally convex), leading us to effectively use gradient optimization to invert for both elasticity and viscosity. The resulting methodology is verified with synthetic data polluted with noise, leading to the conclusion that the proposed FWI is effective in estimating arterial viscoelasticity. Significance. Accurate estimation of arterial viscoelasticity, not just elasticity, provides a more precise characterization of arterial mechanical properties, potentially leading to a better indicator of arterial health.
Screening left ventricular systolic dysfunction in children using intrinsic frequencies of carotid pressure waveforms measured by a novel smartphone-based device
Authors: Cheng Andrew L , Liu Jing , Bravo Stephen , Miller Jennifer C , Pahlevan Niema M 
Published: February 2023

Abstract

Objective. Children with heart failure have higher rates of emergency department utilization, health care expenditure, and hospitalization. Therefore, a need exists for a simple, non-invasive, and inexpensive method of screening for left ventricular (LV) dysfunction. We recently demonstrated the practicality and reliability of a wireless smartphone-based handheld device in capturing carotid pressure waveforms and deriving cardiovascular intrinsic frequencies (IFs) in children with normal LV function. Our goal in this study was to demonstrate that an IF-based machine learning method (IF-ML) applied to noninvasive carotid pressure waveforms can distinguish between normal and abnormal LV ejection fraction (LVEF) in pediatric patients. Approach. Fifty patients ages 0 to 21 years underwent LVEF measurement by echocardiogram or cardiac magnetic resonance imaging. On the same day, patients had carotid waveforms recorded using Vivio. The exclusion criterion was known vascular disease that would interfere with obtaining a carotid artery pulse. We adopted a hybrid IF- Machine Learning (IF-ML) method by applying physiologically relevant IF parameters as inputs to Decision Tree classifiers. The threshold for low LVEF was chosen as <50%. Main results. The proposed IF-ML method was able to detect an abnormal LVEF with an accuracy of 92% (sensitivity = 100%, specificity = 89%, area under the curve (AUC) = 0.95). Consistent with previous clinical studies, the IF parameter

ω

1

was elevated among patients with reduced LVEF. Significance. A hybrid IF-ML method applied on a carotid waveform recorded by a hand-held smartphone-based device can differentiate between normal and abnormal LV systolic function in children with normal cardiac anatomy.
Exploration of temperature stability of linearity and RF performance metrics for PGP negative capacitance FET
Authors: Chaudhary Shalini , Dewan Basudha , Singh Devenderpal , Sahu Chitrakant , Yadav Menka 
Published: February 2023

Abstract
The present work focuses on investigating the performance of partial ground plane selective buried oxide negative capacitance (NC) field-effect transistor (NCFET) electrical properties at high temperatures. The performance of the device has been studied between the temperature of 300–400 K using the Landau–Khalatnikov equation with the Poisson’s equation. In NCFET, ferroelectric material in the gate stack generates NC effect that enhances the device performance by the voltage amplification process. Doped

H
F

O

2

is used as the ferroelectric material because of its high dielectric capacitance and reliable polarization rate. This work primarily focuses on examining the effects of temperature change on the device’s dc performance metrics, analog/radio frequency performance parameters, and linearity performance parameters. Compared to kT/q, sub-threshold slope rises more rapidly as temperature rises and diminishing the ferroelectric effect after 350 K. Also reduced intrinsic delay at higher temperatures make the device an great option for ultra-low-power and high switching speed applications. Additionally, the proposed device performs better in terms of linearity at greater temperatures.