bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Ar-ion irradiation on electrical transport of WS2 monolayer
Authors: Luhar Bhumit , Thakur Deepa , Naik B Raju , Balakrishnan Viswanath 
Published: July 2024

Abstract
Two-dimensional transition metal dichalcogenides (2D-TMDs), such as WS2 and MoS2, have attracted exceptional attention as promising materials for future optoelectronic systems due to their unique properties, including a direct band gap, high quantum efficiency, and flexibility. However, exploiting these materials’ potential in their pristine state remains a key challenge because of limited tunability and control over their properties. The introduction of crystal defects, such as vacancies and dopants, induces localized mid-gap states in 2D materials, enhances electrical transport, and creates a platform for tuning and exploiting these materials for practical applications. Our study explores the effect of Ar-ion beam irradiation on monolayer WS2, resulting in enhanced electrical transport compared to the pristine sample. We regulated the Ar-ion bombardment energy to vary the defect concentration from 0.1 to 0.5 keV. Photoluminescence (PL) and Raman investigations, revealed the extent of damage to the material. At the same time, x-ray photoelectron spectroscopy showed changes in the oxidation state with increasing irradiation energy. Our results demonstrated that Ar-ion treatment at low-energy irradiation enhanced electrical transport by ∼12 fold compared to pristine till 0.2 keV of irradiation by incorporating defects. However, higher irradiation energies reduced electrical transport due to increased disorder in the WS2 monolayer. This investigation highlights the potential for controlled defect engineering to optimize the properties of 2D-TMDs for practical applications.
The electric dipole characteristics of well-deformed 171,173Yb
Authors: Hoşgör G , Tabar E , Kemah E , Yakut H 
Published: July 2024

Abstract
The electric dipole response of well-deformed 171,173Yb in the giant dipole resonance (GDR) and pygmy dipole resonance (PDR) range has been theoretically analyzed using the translation and Galileo invariant quasiparticle phonon nuclear model (TGI-QPNM). The TGI-QPNM consists of an axially symmetric Woods-Saxon Potential, monopole pairing, dipole-dipole residual interaction, and the restoration terms for broken translation and Galilean symmetries. Numerical calculations show the existence of considerable E1 excitations around the neutron separation threshold (S

n
) in both isotopes. The TGI-QPNM results of the photoabsorption cross-section give a double-humped shape in both nuclei, consistent with the available experimental data. The integrated moments (σ
0, σ
−1) and the centroid energies in the GDR region are also reproduced well.
Disordered magnetic ground state in a quasi-1-D d
4 columnar iridate Sr3LiIrO6
Authors: Bandyopadhyay Abhisek , Das Debu , Chakraborty A , Bhowal S , Kumar Vinod , Stenning G B G , Ritter C , Adroja D T , Moretti Sala M , Efimenko A , Meneghini C , Bert F , Biswas P K , Dasgupta I , Saha Dasgupta T , Mahajan A V , Ray Sugata 
Published: July 2024

Abstract
Spin–orbit coupling offers a large variety of novel and extraordinary magnetic and electronic properties in otherwise ‘ordinary pool’ of heavy ion oxides. Here we present a detailed study on an apparently isolated hexagonal 2H spin-chain d
4 iridate Sr3LiIrO6 with geometric frustration. Our structural studies reveal Li–Ir chemical order with desired stoichiometry in this compound, while x-ray absorption together with x-ray photoemission spectroscopic characterizations establish pure 5+ valence of Ir. We have established a magnetic ground state with finite Ir5+ magnetic moments in this compound, contrary to the anticipated nonmagnetic

J

eff

= 0 state, through combined dc susceptibility,

7

Li nuclear magnetic resonance (NMR), muon spin relaxation (µSR) and ab-initio electronic structure studies. These investigations together with ac magnetic susceptibility and specific heat measurements reveal that despite having noticeable antiferromagnetic correlation among the Ir5+ local moments, this system does not magnetically order down to at least 0.05 K, possibly due to geometrical exchange frustration, arising from the comparable nearest- and next-nearest-neighbor interchain Ir–O–O–Ir superexchange interaction strengths with opposite signs. However, the zero-field µSR analysis shows emergence of a considerable proportion of spin-freezing on top of a spin-fluctuating dynamic magnetic background down to the lowest measured temperature of 1.7 K, possibly due to some inhomogeneity and/or the much stronger intra-column Ir–Ir magnetic exchange interaction strength relative to the inter-column Ir–Ir ones. The linear temperature dependence of the magnetic specific heat (

C

m

) in both zero and applied magnetic fields, plus the power-law behavior of the NMR spin-lattice relaxation rate suggest a gapless spinon density of states in this charge gapped disordered magnetic ground state of Sr3LiIrO6.
Gap measurement method based on projection lines and convex analysis of 3D points cloud
Authors: Pan Wei , Jiang Bin-feng , Tang Wen-ming , Wu Fu-pei , Li Sheng-ping 
Published: July 2024

Abstract
Accurate measurement of the gap between the lower surface of the relay and the ground is critical for ensuring the quality of the finished product. Traditional gap measurement methods have some shortcomings, such as low accuracy, poor robustness, and loss of depth clues in obscured areas. In this study, a novel gap measurement method based on computer vision is proposed, which includes a projection line model based on guided filtering and a 3D surface point cloud model based on a three-dimensional plane reference. The relay gap was measured by calculating the projection lines of the upper and lower surfaces of the gap with an error of ± 0.016 mm. A 3D point cloud model captures the key features of the underside of the relay through image processing techniques, and combines convex hull and centroid estimation to construct a three-dimensional reference plane for the gap, which could achieve high-precision, real-time measurement of the gap (with an error less than ± 0.0087 mm). The experimental measurement results show that the proposed method is better than the SelfConvNet method, which has a high measurement accuracy and strong anti-interference ability, and an accuracy rate of up to 99.5% in factory relay quality inspection experiments.
A mixer architecture using GaN-based split-gate nanowire transistor
Authors: Jha Jaya , Surapaneni Sreenadh , Ganguly Swaroop , Saha Dipankar 
Published: July 2024

Abstract
Frequency mixer is an essential block in radio-frequency signal processing for frequency translation and phase comparison. The most common mixers are fabricated using passive elements which suffer from significant conversion loss and low isolation. Mixers using active devices are used less frequently and rather less matured on GaN technology. Here, we demonstrate a mixer based on GaN split-gate nanowire transistor, allowing low conversion loss and high isolation. A constriction is formed by electrostatic modulation of the effective gate width. The threshold voltage of the transistor is modified by one of the gate voltages through the width variation, while the other gate voltage biases the transistor in the saturation region. The nonlinear dependency of the transistor characteristics on the two gate voltages facilitates frequency translation. The mixing characteristics of this architecture are verified both experimentally and theoretically. The output power spectral density peaks at the difference frequency with a minimal conversion loss. Extremely high isolation is measured using three-port S-parameter measurements. The proposed architecture shows multiple benefits, additionally facilitating monolithic mixers on the GaN platform.
Holistic evaluation of a machine learning-based timing calibration for PET detectors under varying data sparsity
Authors: Naunheim Stephan , Mueller Florian , Nadig Vanessa , Kuhl Yannick , Breuer Johannes , Zhang Nan , Cho Sanghee , Kapusta Maciej , Mintzer Robert , Judenhofer Martin , Schulz Volkmar 
Published: July 2024

Abstract

Objective. Modern PET scanners offer precise TOF information, improving the SNR of the reconstructed images. Timing calibrations are performed to reduce the worsening effects of the system components and provide valuable TOF information. Traditional calibration procedures often provide static or linear corrections, with the drawback that higher-order skews or event-to-event corrections are not addressed. Novel research demonstrated significant improvements in the reachable timing resolutions when combining conventional calibration approaches with machine learning, with the disadvantage of extensive calibration times infeasible for a clinical application. In this work, we made the first steps towards an in-system application and analyzed the effects of varying data sparsity on a machine learning timing calibration, aiming to accelerate the calibration time. Furthermore, we demonstrated the versatility of our calibration concept by applying the procedure for the first time to analog readout technology. Approach. We modified experimentally acquired calibration data used for training regarding their statistical and spatial sparsity, mimicking reduced measurement time and variability of the training data. Trained models were tested on unseen test data, characterized by fine spatial sampling and rich statistics. In total, 80 decision tree models with the same hyperparameter settings, were trained and holistically evaluated regarding data scientific, physics-based, and PET-based quality criteria. Main results. The calibration procedure can be heavily reduced from several days to some minutes without sacrificing quality and still significantly improving the timing resolution from

(
304
±
5
)

ps

to

(
216
±
1
)

ps

compared to conventionally used analytical calibration methods.Significance. This work serves as the first step in making the developed machine learning-based calibration suitable for an in-system application to profit from the method’s capabilities on the system level. Furthermore, this work demonstrates the functionality of the methodology on detectors using analog readout technology. The proposed holistic evaluation criteria here serve as a guideline for future evaluations of machine learning-based calibration approaches.
Collection efficiencies of cylindrical and plane parallel ionization chambers: analytical and numerical results and implications for experimentally determined correction factors
Authors: Fenwick John D , Kumar Sudhir , Pardo-Montero Juan 
Published: July 2024

Abstract

Objectives. To derive a collection efficiency formula,

f

Gauss

, for cylindrical ionization chambers in pulsed radiation beams from a volume recombination model of Boag et al (1996 Phys. Med. Biol.
41 885–97) including free electrons. To validate

f

Gauss

and a parallel plate chamber formula

f

exp

using an ion transport code and calculate changes in collection efficiencies caused by electric field charge screening at 0.1–100 mGy doses-per-pulse. And to determine collection efficiencies

C

E

∞

predicted at infinite voltage in the absence of avalanche effects by fitting scaled formulae to efficiencies computed for 100–400 V chamber voltages and 10 and 100 mGy doses-per-pulse. Approach. Calculations were performed for an idealized parallel plate chamber with 2 mm electrode separation

d

, and for an idealized cylindrical chamber with 0.5 and 2.333 mm inner and electrode radii

r

in

and

r

out

. Main results.

f

Gauss

and

f

exp

predict the same collection efficiencies for cylindrical and parallel plate chambers satisfying

d
2

=

(

r

out

2

−

r

in

2

)

ln

(

r

out

/

r

in

)

/

2

, an equivalence condition met by the chambers studied. Without charge screening, efficiencies computed using the code equalled

f

Gauss

and

f

exp

. With screening, efficiencies changed by ⩽0.03%, ⩽1.1% and ⩽21.3% at 1, 10 and 100 mGy doses-per-pulse, and differed between the chambers by ⩽0.9% and ⩽19.6% at ⩽10 and 100 mGy dose-per-pulse. For fits of

f

exp

and

f

Gauss

,

C

E

∞

values were ⩽1.2% and ⩽17.6% from unity at 10 and 100 mGy per pulse respectively, closer than for other formulae tested. Significance. Allowing for screening,

f

Gauss

and

f

exp

described computed collection efficiencies to within 0.03%, 1.1% and 21.3% at doses-per-pulse ⩽1, 10 and 100 mGy. Equivalence of the two chambers broke down at 100 mGy per pulse. Departures of

C

E

∞

values from unity suggest that collection efficiencies determined experimentally by fitting

f

Gauss

or

f

exp

to readings made at multiple voltages will be accurate to within 1.2% and 17.6% at 10 and 100 mGy per pulse respectively.
Active gel model for one-dimensional cell migration coupling actin flow and adhesion dynamics
Authors: Wössner Valentin , Drozdowski Oliver M , Ziebert Falko , Schwarz Ulrich S 
Published: July 2024

Abstract
Migration of animal cells is based on the interplay between actin polymerization at the front, adhesion along the cell-substrate interface, and actomyosin contractility at the back. Active gel theory has been used before to demonstrate that actomyosin contractility is sufficient for polarization and self-sustained cell migration in the absence of external cues, but did not consider the dynamics of adhesion. Likewise, migration models based on the mechanosensitive dynamics of adhesion receptors usually do not include the global dynamics of intracellular flow. Here we show that both aspects can be combined in a minimal active gel model for one-dimensional cell migration with dynamic adhesion. This model demonstrates that load sharing between the adhesion receptors leads to symmetry breaking, with stronger adhesion at the front, and that bistability of migration arises for intermediate adhesiveness. Local variations in adhesiveness are sufficient to switch between sessile and motile states, in qualitative agreement with experiments.
Simulation of perovskite solar cell with transparent contacts for solar windows
Authors: Mohd Fuad Mohamad Fathul Bari , Rammely Najihah , Pakhuruddin Mohd Zamir 
Published: July 2024

Abstract
In recent years, halide-based perovskite solar cells (PSC) have caught worldwide attention since their power conversion efficiency (PCE) has surpassed 25% with low fabrication cost and high scalability. The semi-transparent PSC (ST-PSC) is suitable for building-integrated photovoltaic (BIPV) applications, especially for solar windows. The ST-PSC must demonstrate a reasonable balance between PCE and transparency in the visible region for solar windows, which is inversely proportional to each other. This work studies ST-PSC based on methylammonium lead triiodide (MAPbI3) as solar windows using the General-Purpose Photovoltaic Device Model (GPVDM) and OPAL 2 as the simulation platforms. Parameters such as methylammonium lead triiodide (MAPbI3) thickness, silver (Ag) contact thickness and indium tin oxide (ITO) transparent contact thickness are investigated in relation to the PCE and average visible transmission (AVT). The results demonstrate that the ST-PSC with MAPbI3 thickness of 500 nm and ITO bottom transparent contact of 100 nm leads to PCE of 22.85% and AVT of 11.36%. These parameters represent the best results obtained in this work.
Gompherna globosa flower extract-driven ZnO nanoparticles for enhanced antimicrobial and photocatalytic properties
Authors: D Nivethika , P Raji 
Published: July 2024

Abstract
The aqueous extract of Gomphrena globosa flowers was utilized for the first time as an effective capping and reducing agent for the synthesis of zinc oxide nanoparticles (ZnO NPs). The synthesized nanoparticles were examined using x-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive x-ray analysis (EDAX), Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) and UV–vis spectroscopy. XRD revealed the single-phase wurtzite structure of ZnO nanoparticles with a P63mc space group with an average size of 23 nm. The band gap of synthesized ZnO nanoparticles was determined as 3.16 eV from UV–vis spectroscopy. The rod-shaped structure of the synthesized ZnO NPs was revealed by SEM. The presence of the elements Zn & O was confirmed by EDAX. TEM and SAED confirmed that the average particle size was 26 nm and that the material was polycrystalline. The bio-inspired ZnO NPs achieved outstanding degradation activity of 95.4% against Malachite Green dye after 20 min of UV illumination. The antibacterial properties of the green synthesized nanoparticles were assessed in relation to gram-positive (Staphylococcus sp., Bacillus sp.,) and gram-negative (E. coli, Klebsiella sp.) bacteria. ZnO nanoparticles possess strong antifungal property against a pathogenic fungus Aspergillus niger. This study shows that green-synthesized ZnO nanoparticles derived from Gomphrena globosa flower extract are recommended for use in anti-microbial and photocatalytic applications.
Decoupling beam power and beam energy on ASDEX Upgrade NBI with an in-situ variable extraction gap system
Authors: Hopf C. , Harder N. den , Heinemann B. , Angioni C. , Plank U. , Weiland M. ,   the ASDEX Upgrade Team
Published: July 2024

Abstract
In early 2022 one source of ASDEX Upgrade’s (AUG) neutral beam injector 2 was equipped with a first-of-its-kind beam extraction grid system with in-situ variable extraction/acceleration gap that allows one to choose beam energy and beam power independently in a wide operational space, greatly enhancing experimental flexibility. The gap can be changed from one AUG discharge to the next. The extended operational space makes it possible to reduce beam energy and shine through while maintaining high heating power, or to reduce NBI power at high beam energy, e.g. to stay in L mode. Furthermore, the feature opens the door for advanced control of heat and torque deposition, such as to change torque and ion-to-electron heating ratio at constant power. The prototype system was successfully tested in 2022 and already found first applications in AUG’s physics programme. The remaining three sources of the same injector will also be equipped with variable gaps during the 2022–24 opening of AUG and installation of this new system on all sources of NBI 1 is also under discussion in order to exploit the full potential of the new feature.
Surface wettability control of bubble flow guide for a thin aqueous electrolyte layer of solar photoelectrochemical reactors
Authors: Kameya Yuki , Hasegawa Ryosuke , Osawa Tatsuya 
Published: July 2024

Abstract
Hydrogen is a promising energy carrier as no carbon dioxide is emitted during its use in fuel cells or combustion. Solar photoelectrochemical water splitting is a potential process for producing renewable hydrogen. Herein, energy transport phenomena are addressed for the future design of large-scale reactors. First, we show that the thickness of the aqueous electrolyte layer is an essential factor for utilizing the full spectrum of solar radiation. The transport of solar irradiation through the aqueous electrolyte is theoretically analysed. Next, based on the measurement of light transmission through hydrogen bubbles generated from a hydrogen evolving electrode, the energy loss caused by the bubbles covering a photoelectrode is discussed. The bubble size distributions at practical current densities are also presented. Then, a bubble flow guide for controlling the stream of bubbles in a thin electrolyte layer is proposed. A design strategy and experimental results verifying the performance of the bubble flow guide are presented. We demonstrate that surface wettability and inclination angle are important for designing an effective bubble flow guide. We examine the surface wettability control using hydrophilic coatings in detail. Changes in the water contact angles as well as bubble adhesion forces on the coated surfaces are demonstrated. In addition, the current experimental method can be used to identify essential issues in photoelectrochemical processes. Because bubble trapping and growth in a flow guide are reflected in the electrode potential variation, the discussion of electrode potential variation would be useful for further developing bubble flow guides. Overall, this study demonstrates the potential for developing and designing solar photoelectrochemical reactors.
Performance prediction and analysis of a solar assisted medium-deep geothermal heating system
Authors: Zhang Z B , Tao Z Y , Ma Z D , Jia G S , Saw L H , Jin L W 
Published: July 2024

AbstractThe solar assisted medium-deep geothermal heating (SAMGH) system is a novel kind of heating system that can combine the benefits of geothermal and solar energy. However, the variations in borehole heat exchanger (BHE) performance and the intermittency of solar energy pose challenges for predicting the overall performance of the coupled system and designing the operational strategies. To conduct simulation on the SAMGH system for performance prediction and analysis, a coaxial medium-deep borehole heat exchanger coupled with the solar energy heating system for an office building in Xi’an was developed. The TRNSYS software was employed to establish the model of the coupled system. A ground source heat pump (GSHP) heating system was used for comparison. The simulation results showed that with the introduction of the solar energy and heat storage modules, the annual operating time of the geothermal system only accounts for 32.06%. The energy consumption of the coupled system can be reduced from 63585 kW to 44586 kW, and the energy consumption proportion of the geothermal system in total value decreased from 69.10% to 40.58%. Therefore, the average coefficient of performance (COP) of the heat pump and the system were improved by 63.71% and 91.77%, respectively. Moreover, because the solar energy is beneficial to the ground heat recovery, the average ground temperature increased from 42.5 °C to 43.88 °C after ten years of operation. The proposed design method and simulation results can serve as a reference for design method and performance analysis of the geothermal and solar coupled system.
Numerical investigation of the effects of increased and mixed chord lengths for a 4-bladed darrieus vertical axis wind turbine
Authors: Wong K H , Lim C T J , Ng J H , Fazlizan A , Wang X H 
Published: July 2024

Abstract
Increasing amounts of study and research on vertical axis wind turbines (VAWTs) have shown that they are a competitive option in wind energy power generation. However, the VAWT’s primary drawback is low power efficiencies. Although there are several studies on the effects of solidity on Darrieus VAWT performances, few focus on the effect of the aerofoil chord length. Hence, in the present study, 2D numerical simulations are performed to explore the effects of different aerofoil chord lengths on the performance of a Darrieus VAWT. The simulation was first validated with the experimental data from the literature. The studied turbine is a 4-bladed VAWT fitted with NACA0021 blades with an original chord length, c of 85.8 mm and another with an increased chord length of 1.2 c (102.96 mm). Additionally, a modified rotor geometry with mixed chord lengths of c and 1.2 c to improve turbine performance is proposed and investigated. The coefficients of power (C
P) and torque (C
T) for tip speed ratios (TSRs) between 1.4 and 3.3 for each of the turbines are evaluated and comparatively analysed. All the data was obtained using the computational fluid dynamics (CFD) software ANSYS Fluent in conjunction with the shear stress transport (SST) k−ω turbulence model. The findings show that the turbine with 1.2 c chord length and hence larger solidity outperforms those with smaller chord lengths at low TSRs. However, their performances decrease significantly at TSRs above 2.5, resulting in up to 86.1% lower C
P values. The mixed chord lengths case was successful at achieving significantly higher C
P values at both TSR ranges with only a decrease of 3.03% in maximum C
P at its optimum TSR.