bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen reduction through specific surface area control of AlN powder for AlN single-crystal growth by physical vapor transport
Authors: Wang Ze-Ren , Zhu Xing-Yu , Zhao Qi-Yue , Wu Jie-Jun , Yu Tong-Jun 
Published: January 2024

Abstract
In the physical vapor transport (PVT) growth of AlN, re-oxidation of aluminum nitride (AlN) source powder happening in the process of setting seed crystal into crucible seems to be unavoidable. This process introduces oxygen just before AlN growth and has a significant impact on the crystal quality. In this paper, a high and low-temperature alternative sintering method (HLAS) is proposed based on the idea of specific surface area control to reduce the re-oxidation of AlN source powder. This method introduces cyclic sintering between 1500 °C and 1900 °C to the conventional three-step treatment repeatedly, which utilizes possible phase-transition along with the processes of powder sintering back and forth to increase the particle size and decrease the specific surface area significantly. The scanning electron microscope and Brunauer, Emmett, and Teller results showed that the specific surface area of AlN powder treated with the HLAS method can be reduced to one-third of that with the conventional method. Thus, the secondary ion mass spectrometry confirmed the reduction of oxygen impurity in AlN single-crystals to a good level of 1.5 × 1017 cm−3. It is clear that this HLAS process is an effective way of controlling the specific surface area of AlN source powder, which contributes to the suppression of oxygen influence on PVT-AlN growth.
Bi-directional threshold voltage shift of amorphous InGaZnO thin film transistors under alternating bias stress
Authors: Kim Hyunjin , Kim Beom Jung , Oh Jungyeop , Choi Sung-Yool , Park Hamin 
Published: January 2024

Abstract
Amorphous InGaZnO (a-IGZO) has attracted a lot of attention as a high-mobility channel material for thin film transistors (TFTs). However, the instability mechanism involving threshold voltage and subthreshold swing (SS) in a-IGZO TFTs still requires further investigation. In this study, we investigated the electrical instability of amorphous InGaZnO TFTs subjected to alternating positive and negative bias stresses. Based on the respective mechanisms under positive and negative bias stresses, including ionization and spatial movement of oxygen vacancies, bi-directional threshold voltage shifts were observed under alternating bias stress. The SS values vary with the bias stress polarity, reflecting the presence and distribution of oxygen vacancies. Our findings reveal a complementary mechanism based on oxygen vacancies, elucidating the behavior under complex bias stress schemes and extending our understanding of instability mechanisms beyond monotonous bias stress.
Strain engineering and strain measurement by spring tethers on suspended epitaxial GaN-on-Si photonic crystal devices
Authors: Wang Jun , Houdré Romuald 
Published: January 2024

Abstract
Suspended epitaxial gallium nitride (GaN) on silicon (Si) photonic crystal devices suffer from large residual tensile strain, especially for long waveguides, because fine structures tend to crack due to large stress. By introducing spring-like tethers, designed by the combination of a spring network model and finite element method simulations, the stress at critical locations was mitigated and the cracking issue was solved. Meanwhile, the tethered-beam structure was found to be potentially a powerful method for high-precision strain measurement in tensile thin films, and in this case, a strain of

2.27
(
±
0.01
)
×

10

−
3

was measured in 350 nm epitaxial GaN-on-Si.
Dual-directional SCR device with dual-gate controlled mechanism for ESD protection in photoelectric chip
Authors: Liu Yujie , Wang Yang , Yang Jian , Jin Xiangliang 
Published: January 2024

Abstract
The dual-directional silicon-controlled rectifier (DDSCR) is an electrostatic discharge (ESD) protection device. It can provide positive and negative ESD surge paths and has excellent robustness. However, industry-level sensors operating in strong electromagnetic interference environments impose higher reliability requirements on photoelectric chips. This paper proposed a novel DDSCR with a dual-gate controlled mechanism. By incorporating the gate diode triggering and the gate field modulation mechanism into the traditional DDSCR, and further utilizing additional parasitic bipolar junction transistors (BJTs) for diversion, the proposed device exhibits significantly improved ESD characteristics. Measurement results indicate that, compared to DDSCR, the proposed device exhibits a 27.5% reduction in trigger voltage (Vt1
), a 96.1% improvement in holding voltage (Vh
), and achieves an equivalent human body model protection level of 11.45 kV, demonstrating exceptional design area efficiency. The experimental findings validate the effectiveness of the proposed device in 5 V photoelectric chip applications.
Flexural behaviour of cementitious composites embedded with 3D printed re-entrant chiral auxetic meshes
Authors: Zahra Tatheer , Asad Mohammad , Thamboo Julian 
Published: January 2024

Abstract
3D printed auxetic metamaterials can be used to make high performing cementitious composites to strengthen existing structures and elements due to their negative Poisson’s ratio behaviour and high energy absorbing characteristics. In this paper, three different re-entrant chiral auxetic (RCA) meshes of various cell geometries and orientations were developed by 3D printing them using poly-lactic acid (PLA) and thermoplastic polyurethane (TPU) filament. The developed meshes were tested under out-of-plane flexure to study their load carrying capacity, ductility and energy absorption characteristics, especially to characterise the best cell orientation. The horizontal cells provided enhanced load carrying and energy absorption characteristics for all three cell geometries for both materials. These RCA meshes were then embedded into low and high strength premix cement mortar matrices to develop auxetic cementitious composites (ACCs). In total, 42 ACC specimens were casted and tested under flexural loading. The results were studied in terms of their failure patterns, load-displacement responses, flexural capacities, ductility and energy absorption. The RCA meshes made of PLA filament showed limited capacity and energy absorption as compared to RCA meshes made of TPU filament due to extended flexibility and resilience provided by TPU meshes. The RCA meshes with a denser cell structure exhibited highest flexural capacity and effective energy absorption of 14 700 kJ m−2 for TPU-RCA mesh embedded into high strength cement mortar matrix. The results obtained in this study have enabled to understand the flexural behaviour of cementitious composites embedded with 3D printed auxetic lattices and to strengthen the existing structures.
Design of auxetic cellular structures for in-plane response through out-of-plane actuation of stimuli-responsive bridge films
Authors: Chandramouli Anirudh , Rapaka Sri Datta , Annabattula Ratna Kumar 
Published: January 2024

Abstract
In this work, we propose novel designs of cellular structures exhibiting unconventional in-plane actuation responses to external stimuli. We strategically introduce stimuli-responsive bilayer bridge films within conventional honeycombs to achieve the desired actuation. The films are incorporated such that, in response to an external field (thermal, electric, chemical, etc), the bridge film bends out-of-plane, activating the honeycomb in the plane. The conventional out-of-plane deformation of the bridge film can lead to interesting and unconventional actuation in the plane. An analytical model of this coupled unit cell behavior is developed using curved beam theory, and the model is validated against finite element simulations. Several applications of such designs are presented. Unit cell architectures exhibiting both positive and negative macroscopic actuation are proposed, and the criterion for achieving such actuation is derived analytically. Furthermore, we demonstrate that by altering the topology, unidirectional and bidirectional negative actuation can be achieved. We also propose designs that result in the negative actuation of the structure with both monotonically increasing and monotonically decreasing stimuli. Finally, by combining two macroscopic structures with positive and negative actuation, we design actuators/sensors that bend in the plane in response to a stimulus.
In-vivo studies on PDMS-embedded fiber Bragg grating based smart laparoscopic grasper
Authors: Chandana H , Chalackal Archana Trikkaikuth , Subbaraj Pravin Kumar , Kanakambaran Srijith 
Published: January 2024

Abstract
Minimally invasive surgeries are often associated with the risk of tissue damage due to improper force feedback mechanisms to notify surgeons regarding the force thresholds. This work evaluates the grasping forces during tissue handling to offer force feedback and assist surgeons during tissue manipulation. A polydimethylsiloxane embedded fiber Bragg grating sensor was developed and integrated at the tip of the laparoscopic grasper to measure the grasping force. Simulation studies have been performed to investigate the performance of the embedded grating sensor. The sensitivity of the sensor embedded within polydimethylsiloxane was found to be around 31.4 pm N−1 which was better compared to that of a silicone embedded counterpart. In-vivo studies were performed with soft tissue phantoms prepared with silicone rubber interspersed with different concentrations of mineral oil. Experimental results reveal a decrease in the peak wavelength shift as the tissue gets softer which is consistent with the nature of grasping force for softer tissues.
Very strong levitation force and stability achieved with a large MgB2 superconductor disc
Authors: Xing Yiteng , Russo Giacomo , Ribani Pier Luigi , Morandi Antonio , Bernstein Pierre , Rossit Julie , Lemonnier Sebastien , Delorme Fabian , Noudem Jacques 
Published: January 2024

Abstract
This rapid communication highlights a remarkable achievement obtained with a 120 mm diameter large cylindrical MgB2 bulk: the measurement of magnetic levitation forces up to 700 N at 20 K, levitation being stable up to levitation forces exceeding 400 N. The investigated sample, which has one of the largest dimensions reported in the literature, was fabricated using the unconventional spark plasma sintering technique. This method is known as one of the most efficient methods for producing dense MgB2 samples. This breakthrough holds significant potential for advancing high-performance levitation systems and superconducting applications, including high-speed transportation systems and magnetic bearings.
Review of materials for HTS magnet impregnation
Authors: Feldman Joshua , Stautner Wolfgang , Kovacs Christopher , Miljkovic Nenad , Haran Kiruba S 
Published: January 2024

Abstract
Construction of high-temperature superconducting magnets typically involves impregnation of a coil in a liquid medium, such as epoxy, which is then solidified. This impregnation provides mechanical integrity to the magnet and facilitates heat transfer. The choice of material used for impregnation requires careful consideration of the material properties and the performance requirements in order to ensure optimal magnet operation. This paper offers a comprehensive educational resource on this topic, reviewing the literature available on materials for magnet impregnation. A detailed explanation of considerations for selecting an impregnation material are presented, along with a review of several types of materials and their characteristics as reported in the literature. The materials are compared, and their suitability to different applications is discussed. Topics for future research are suggested.
A novel method for temperature self-sensing of reinforced concrete
Authors: Ozturk Murat 
Published: January 2024

Abstract
In this work, a temperature-sensing reinforced concrete has been developed using capacitance and resistance-based measurements. No additives are required for self-temperature sensing. Steel bars in the reinforced concrete are used as electrodes. To determine the self-sensing properties of the reinforced concrete specimen, it is cooled from room temperature to −9 °C and heated from room temperature until it reaches 50.9 °C. The varying capacitance and resistance values of the sample concerning temperature changes are evaluated. Fractional changes in capacitance and resistance upon cooling are 80.6% and 276%, respectively. Fractional changes in capacitance and resistance upon warming are 60% and 35%, respectively. Temperature coefficients of capacitance and resistance (fractional change in capacitance and resistance per unit change in temperature) upon cooling are 2.5 × 10−2/°C and 8.6 × 10−2/°C, while upon warming they are 2.2 × 10−2/°C and 1.3 × 10−2/°C. This study aims to use capacitance and resistance-based sensing techniques to detect temperature variations in steel-reinforced concrete structures. Further studies are planned to investigate various factors such as moisture, porosity, aggregate proportion, and water content that affect the self-temperature-sensing performance of reinforced concrete.
Electronic, optical, and thermoelectric properties of vacancy-ordered double perovskite K2SnX6 (X = Cl, Br, I) from first-principle calculations
Authors: Zikem A , Baaziz H , Ghellab T , Charifi Z , Soyalp F 
Published: January 2024

Abstract
The present study explores the structural, optoelectronic, and thermoelectric properties of potassium tin halide vacancy-ordered double perovskites K2SnX6 (X = Cl, Br, and I) in their stable monoclinic phase. Our study uses first-principles calculations based on density functional theory (DFT). Electronic band structures reveal direct band gaps for K2SnCl6 and K2SnBr6, while K2SnI6 exhibits an indirect band gap. Theoretical computations utilising the modified Becke-Johnson potential (mBJ-GGA) demonstrate that the optical band gaps of K2SnCl6, K2SnBr6, and K2SnI6 decrease in the following order: 2.581 eV, 1.707 eV, and 4.126 eV, respectively. These values render the materials suitable for photovoltaic applications. Analysis of dielectric functions, absorption coefficients, and refractive indices demonstrates their potential as light-absorbing materials. We evaluate the thermoelectric properties, including electronic and lattice thermal conductivities, Seebeck coefficients, and power factors, which lead to favorable thermoelectric performance. The maximum figure of merit (ZT) values of 0.58, 0.69, and 0.50 are achieved for K2SnCl6, K2SnBr6, and K2SnI6, respectively, at 500 K. These findings highlight the potential of these materials for applications in solar cells and thermoelectric devices, emphasising their effectiveness at elevated temperatures.
Infinite versus finite 1D-dielectric gratings supporting SP-BIC modes for sensing applications
Authors: Djemaiai Lylia , Hamidi Mahdi , Mezeghrane Abdelaziz , Belkhir Abderrahmane , Baida Fadi Issam 
Published: January 2024

Abstract
In this paper, we investigate the existence of a special so-called Symmetry-Protected Bound state In the Continuum (SP-BIC) mode in a typical infinite and finite 1D-periodic TiO2-based dielectric structure. Using Finite-Difference Time-Domain (FDTD), Fourier-Modal Method (FMM) and N-order FDTD simulations, a complete optical characterization of the structure is performed. In comparison with the classical Guided Mode Resonance (GMR), the existence and the excitation efficiency of this particular mode are studied with respect to the illumination conditions of the structure and the number of periods when the structure is finite. Our results are an additional contribution to designing efficient resonators for sensing applications. It is shown that for a finite and then more realistic structure, the quality factor is directly related to the number of periods N. It reaches the same value as for the infinite case when the number of periods is N = 200. A high sensitivity, comparable to the infinite case, is also obtained from N = 50.
Image encryption algorithm based on improved iterative chaotic map with infinite collapses and Gray code
Authors: Wang Quanyv , Zhang Xiaoqiang , Zhao Xiaohu 
Published: January 2024

Abstract
The quick advancement of multimedia technology has led to the widespread utilization of digital images across various industries. Meanwhile, image security has become an urgent issue in need of resolution. To guarantee image security as well fulfill the requirements of real-time image cryptosystems, a novel image encryption algorithm is proposed based on the designed improved iterative chaotic map with infinite collapses (ICMIC), Gray code and semi-pixel level permutation and diffusion. Firstly, two chaotic sequences are produced using the improved ICMIC and then they are used to perform scrambling and diffusion operations. Secondly, the plain image is encoded using Gray code and then we convert each Gray code into two semi-pixels. Thirdly, the designed semi-pixel level permutation is used to scramble the semi-pixel vector. Finally, the scrambled semi-pixel vector is diffused using the designed dynamic semi-pixel level diffusion. The performance analyses illustrate that the proposed algorithm possesses robust security and high efficiency, making it ideally suited for application in real-time image cryptosystems.
Cosmic background neutrinos deflected by gravity: DEMNUni simulation analysis
Authors: Hernández-Molinero Beatriz , Carbone Carmelita , Jimenez Raul , Garay Carlos Peña 
Published: January 2024

Abstract
The local supercluster acts as a gravity deflection source for cosmic background
neutrinos. This deflection by gravity changes the neutrino helicity and therefore has important
consequences for ground based tritium capture experiments aimed at determining if the neutrino is
Dirac or Majorana. Here we explore the deflection effect of the local supercluster using two
simulations from the DEMNUni suite characterised by very different mass resolutions, as they are
both filled with 20483 dark matter particles (and an equal number of massive neutrino
particles) but have comoving volumes of (2 h
-1Gpc)3 and (500 h
-1Mpc)3, respectively. We reaffirm our previous results and show that the lightest
neutrinos are ultra-relativistic enough to suffer little deflection by gravity and at the same
time not relativistic enough to achieve the same capture rate for Dirac and Majorana cases. This
means that the capture rate in Ptolemy-like experiments will be sensitive to the neutrino nature
and that gravity deflection enlarges the difference between Majorana and Dirac rates. Moreover,
using the relation between mass and momentum of the neutrinos frozen Fermi-Dirac distribution, but
taking into consideration gravity corrections, we are able to calculate the deflection angle for
different neutrino masses from the same set of neutrinos obtained from the simulation. Doing so,
we provide a formula to compute the deflection angle for any neutrino mass, such that when
cosmology detects an absolute neutrino mass, precise predictions can be made for tritium
ground-based detectors on Earth aimed to determine neutrinos nature.
The fate of a quantum-corrected collapsing star in General Relativity
Authors: Gupta Choudhury Shibendu , Chakrabarti Soumya 
Published: January 2024

Abstract
We incorporate some corrections inspired by loop quantum gravity into the concept of gravitational collapse and propose a complete model of the dynamic process. The model carries the essence of a mass-independent upper bound on the curvature scalars, originally found as a crucial feature of black holes in loop quantum gravity. The quantum-inspired interior is immersed in a geometry filled with null radiation, and they are matched at a distinct boundary hypersurface. The ultimate fate of the process depends on the inhomogeneities of the metric tensor coefficients. We find a critical parameter λ embedded in the inhomogeneity of the conformal factor of the interior metric. Examples with λ< 0 enforce an eventual collapse to singularity, and λ> 0 cases produce a non-singular collapse resulting in a loop-quantum-corrected Schwarzschild geometry modulo a conformal factor. Interestingly, for λ< 0 as well, there exist situations where the quantum effects are able to cause a bounce but fall short of preventing the ultimate formation of a singularity. The trapped surface formation condition is studied for the λ<0 case to infer about the visibility of the final singularity. Interestingly, we find a possibility of the formation of three horizons during the course of the collapse. Eventually, all of them merge into a single horizon, which envelopes the final singularity. For the non-singular case, there is a possibility that the sphere can evolve into a wormhole throat whose radius is found to be inversely proportional to the critical parameter λ. Depending on the nature of evolution and the shell regions, the collapsing shells violate some standard energy conditions, which can be associated with quantum-inspired corrections.
Bimetallic solid solution MAX phase Ti2NbAlC2 as saturable absorber for passively Q-switched Er3+-doped fiber laser
Authors: Zhao Bin , Zhang Hong-Ping , Ma Rong-Ze , Farrell Gerald , Li Zhen-Rui , Wang Peng-Fei 
Published: January 2024

Abstract
In this paper, we demonstrated a stable Q-switched fiber laser operation with a central wavelength of 1531.43 nm using a bimetallic solid solution MAX phase Ti2NbAlC2 saturable absorber. The minimum pulse duration of 3.67 μs and the maximum repetition rate of 32.56 kHz were acquired at the pump power of 300 mW. Furthermore, the Q-switched pulse has a maximum output power of 1.08 mW and a maximum pulse energy of 33.14 nJ. Our results indicate that the Ti2NbAlC2 is a promising saturable absorber material. The bimetallic solid solution MAX phase materials may be developed as novel nonlinear photonic devices with outstanding performance.
Period–Luminosity Relationship for δ Scuti Stars Revisited
Authors: Poro Atila , Jafarzadeh S. Javad , Harzandjadidi Roghaye , Madani Mohammad , Bozorgzadeh Elnaz , Jahangiri Esfandiar , Sarostad Ahmad , Alizadehsabegh Ailar , Hadizadeh Maryam , EsmaeiliVakilabadi Mohammad 
Published: January 2024

Abstract
The Gaia DR3 parallax approach was used to estimate the absolute parameters of 2375 δ Scuti stars from the ASAS catalog. The selected stars have a variety of observational characteristics, with a higher than 80% probability of being δ Scuti stars. We have displayed all the stars in the Hertzsprung–Russell diagram along with the δ Scuti instability strip, the Zero Age Main Sequence and the Terminal Age Main Sequence. Then, we determined which fundamental and overtone modes each star belongs to using pulsation constant (Q) calculations. In addition, we evaluated the parameters in the Q calculation equation using three machine learning methods, which showed that surface gravity and temperature have the greatest effect on its calculation. The Period–Luminosity (P-L) relationship of the δ Scuti stars was also revisited. Eventually, using least squares linear regression, we made four linear fits for fundamental and overtone modes and updated their relationships.