bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of real gas models on the wave dynamics and refrigeration of gas wave rotor
Authors: Zhou Yihui , Gao Feng , Liu Zhijun , Hu Dapeng
Published: July 2024

The gas wave rotor was usually designed and performed on the ideal gas model. However, the real gas effect could not be ignored anymore under high-pressure ratio conditions. In this study, for the first time, a two-dimensional computational model of a double-opening gas wave refrigerator (GWR) using a multi-parameter Benedict–Webb–Rubin equation of state is established and the influence of the real gas effect on gas wave dynamics and energy transfer processes in the GWR with discontinuous boundary conditions is thoroughly investigated. The numerical results show that the wave dynamics of the ideal gas and the real gas are similar under different operating conditions, but compression waves and expansion waves in real gas obviously lag behind the ideal gas. In addition, the low-temperature real gas is completely discharged earlier than the ideal gas and the difference between them gradually increases as the pressure ratio gets higher, which benefits the GWR compact structure design and cost reduction. At the same time, the temperature of the real gas being discharged is lower than that of the ideal gas. Therefore, the refrigeration efficiency of the isentropic expansion of the real gas will be improved compared with the operation in ideal gas. The research results on the real gas effect reveal the mechanism of wave dynamics and energy transfer, providing support for the optimization design of GWR.
What is the origin of slow relaxation modes in highly viscous ionic liquids?
Authors: Eliasen Kira L. , Gabriel Jan , Blochowicz Thomas , Gainaru Catalin P. , Christensen Tage E. , Niss Kristine
Published: July 2024

Room temperature ionic liquids (RTILs) are molten salts consisting entirely of ions and have over the past decades gained increased interest due to their high potential in applications. These structurally complex systems often display multiple relaxation modes in the response functions at lower frequencies, hinting to complex underlying mechanisms. While the existence of these multimodal spectra in the shear mechanical, dielectric, and light scattering response of RTILs has been confirmed multiple times, controversy still surrounds the origin. This paper, therefore, aims to provide additional insights into the multimodal spectra seen in RTILs by presenting new shear mechanical results on seven different RTILs: Pyr1n-TFSI with n = 4, 6, and 8; Pyr18-TFSI mixed with Li-TFSI in two high concentrations; and Cn-mim-BF4 with n = 3 and 8. Dynamic depolarized light scattering was also measured on one of the Pyr18-TFSI Li-salt mixtures. These specific cases were analyzed in detail and put into a bigger perspective together with an overview of the literature. Recent literature offers two specific explanations for the origin of the multimodal shear mechanical spectra: (1) cation–anion time scale separation or (2) combined cation–anion relaxation in addition to a dynamic signal from mesoscale aggregates at lower frequencies. However, neither of these two pictures can consistently explain all the results on different ionic liquids. Instead, we conclude that the origin of the multimodal spectrum is system specific. This underlines the complexity of this class of liquids and shows that great care must be taken when making general conclusions based on specific cases.
Peregrine solitons and resonant radiation in cubic and quadratic media
Authors: Caso-Huerta M. , Bu L. , Chen S. , Trillo S. , Baronio F.
Published: July 2024

We present the fascinating phenomena of resonant radiation emitted by transient rogue waves in cubic and quadratic nonlinear media, particularly those shed from Peregrine solitons, one of the main wavepackets used today to model real-world rogue waves. In cubic media, it turns out that the emission of radiation from a Peregrine soliton can be attributed to the presence of higher-order dispersion, but is affected by the intrinsic local longitudinal variation of the soliton wavenumber. In quadratic media, we reveal that a two-color Peregrine rogue wave can resonantly radiate dispersive waves even in the absence of higher-order dispersion, subjected to a phase-matching mechanism that involves the second-harmonic wave, and to a concomitant difference-frequency generation process. In both cubic and quadratic media, we provide simple analytic criteria for calculating the radiated frequencies in terms of material parameters, showing excellent agreement with numerical simulations.
Concentration and cavitation phenomena of Riemann solutions for the generalized Chaplygin gas equations under the flux approximation
Authors: Shao Zhiqiang , Huang Meixiang
Published: July 2024

In this paper, we investigate the concentration and cavitation phenomena of Riemann solutions for the generalized Chaplygin gas equations in the presence of flux approximation. The concentration and cavitation are fundamental and physical phenomena in fluid dynamics, which can be mathematically described by delta shock waves and vacuums (or constant density states), respectively. The main objective of this paper is to rigorously investigate the formation of delta shock waves and constant density states and observe the concentration and cavitation phenomena. First, the Riemann problem for the generalized Chaplygin gas equations under the flux approximation is solved constructively. Although the system is strictly hyperbolic and its two characteristic fields are genuinely nonlinear, the delta shock wave arises in Riemann solutions. The formation of mechanism for delta shock wave is analyzed, that is, the 1-shock wave curve and the 2-shock wave curve do not intersect each other in the phase plane. Second, it is rigorously proved that, as the pressure vanishes, the Riemann solutions for the generalized Chaplygin gas equations under the flux approximation tend to the two kinds of Riemann solutions to the transport equations in zero-pressure flow under the flux approximation, which include a delta shock wave formed by a weighted δ-measure and a constant density state.
The flame macrostructure and thermoacoustic instability in a centrally staged burner operating in different pilot stage equivalence ratios
Authors: Xiang Jingyuan , Li Jiacheng , Mo Weishu , Wang Bo , Yang Dong , Gan Xiaohua
Published: July 2024

The main focus of this paper is to discover the link between flame macrostructure and thermoacoustic instability in a centrally staged swirl burner. In practical combustors, the flow rate in the pilot stage is much smaller than that in the main stage. However, the modification in the pilot stage could alter the flame macrostructure while maintaining a similar total flow rate. Therefore, the thermoacoustic instability was examined at different flame macrostructures by varying the pilot stage equivalence ratio under identical main stage inlet conditions. High-frequency planar laser measurements and chemiluminescence measurement were conducted to enhance spatial and temporal accuracy, providing a more comprehensive understanding of thermoacoustic instability. Two different flame macrostructures, S-type and I-type flames, were identified based on the preheating zone distribution. They exhibit distinct thermoacoustic instabilities, with the I-type flames demonstrating more intense instability than S-type flames. The results indicate that the variation of flame macrostructure influences the coupling of flame heat release and flow field. Specifically, the preheating zone and heat release of I-type flames exhibit greater sensitivity to flow field fluctuations, resulting in a more intense and complex fluctuation of the flame. This discrepancy leads to variations in thermoacoustic instability intensity, as well as the changes in the phase coupling between heat release and acoustic pressure, which in turn impact the total Rayleigh index. Meanwhile, significant differences exist in the distribution pattern and range of flow field fluctuations between I-type and S-type flames.
Theory for proton-coupled energy transfer
Authors: Cui Kai , Hammes-Schiffer Sharon
Published: July 2024

In the recently discovered proton-coupled energy transfer (PCEnT) mechanism, the transfer of electronic excitation energy between donor and acceptor chromophores is coupled to a proton transfer reaction. Herein, we develop a general theory for PCEnT and derive an analytical expression for the nonadiabatic PCEnT rate constant. This theory treats the transferring hydrogen nucleus quantum mechanically and describes the PCEnT process in terms of nonadiabatic transitions between reactant and product electron–proton vibronic states. The rate constant is expressed as a summation over these vibronic states, and the contribution of each pair of vibronic states depends on the square of the vibronic coupling as well as the spectral convolution integral, which can be viewed as a generalization of the Förster-type spectral overlap integral for vibronic rather than electronic states. The convolution integral also accounts for the common vibrational modes shared by the donor and acceptor chromophores for intramolecular PCEnT. We apply this theory to model systems to investigate the key features of PCEnT processes. The excited vibronic states can contribute significantly to the total PCEnT rate constant, and the common modes can either slow down or speed up the process. Because the pairs of vibronic states that contribute the most to the PCEnT rate constant may correspond to spectroscopically dark states, PCEnT could occur even when there is no apparent overlap between the donor emission and acceptor absorption spectra. This theory will assist in the interpretation of experimental data and will guide the design of additional PCEnT systems.
A numerical investigation on the morphology evolution of compound droplets
Authors: Lv Chao , Ji Zhaoxiang , Zhang Haiwei , Yang Tao , Zhao Hongliang
Published: July 2024

The volume of fluid-continuum surface force model is used to systematically study the influence of characteristic parameters, internal pressure on the dynamic characteristics, finite deformation mode, and fracture mode of compound droplets in air. The simulation results indicate that the morphology evolution of compound droplets can be divided into two stages: expansion deformation stage and irregular deformation stage. And for the first time, it is proposed that the crushing methods of compound droplets can be divided into two types: overall oscillation and local oscillation. Increasing the internal pressure of the compound droplet will cause severe deformation of the compound droplet, and the time required for the expansion and deformation stage will be reduced. However, the influence of fluid interfacial tension and viscosity on the bottom dynamics of compound droplets is often complex, leading to significant changes in the deformation mode of compound droplets. In addition, the influence of feature parameters We and Ca is further discussed. The research results can provide theoretical guidance for precise control of their arrangement in core–shell driven microfluidic technology.
Enhancement of terahertz emission during single-color filamentation by chirping laser pulse
Authors: Rizaev G. , Pushkarev D. , Levus M. , Vrublevskaya N. , Seleznev L.
Published: July 2024

We experimentally demonstrate that terahertz emission yield from single-color filament plasma can be increased by more than 3 times by ordinary laser pulse chirping at constant energy. The enhancement is spectrally selective, for each terahertz frequency there is an optimal laser pulse duration providing maximal terahertz emission. This provides a prospective tool for tailoring both spectrum and energy of the terahertz emission from a single-color filament.
Hydrodynamic performance of a pile-supported oscillating water column breakwater in front of a partially reflecting seawall
Authors: Zhang Yang , Zhu Wenjin , Xu Qing , Kong Dekun , Dong Xiaotian
Published: July 2024

Integrating wave energy devices with breakwaters can offer an innovative and sustainable approach by combining wave power extraction with wave attenuation. The performance of this integrated system in offshore areas is influenced by the unique characteristics of the coastline. In this paper, a semi-analytical solution was developed using the matching eigenfunction method for the oscillating water column device integrated into a pile-supported breakwater in front of a partially reflective seawall. The model was validated through the energy conservation law, the Haskind relationship, and experimental data. Detailed examinations were conducted on the effects of the seawall's reflection coefficients, the distance between the system and the seawall, the wall draft, and the chamber breadth on hydrodynamic performance. Results show that the presence of the seawall significantly influences hydrodynamic coefficients (hydrodynamic efficiency, reflection coefficient, the relative transmitted amplitude, etc.), accompanied by the piston and sloshing mode resonances inside the chamber and the confined area between the system and the seawall. Due to energy dissipated by a partially reflective seawall, the magnitude of those hydrodynamic coefficients is mitigated, together with the piston and sloshing mode resonances inside the air chamber. The cancellation of the sloshing mode resonance inside the confined area is observed for the smaller seawall's reflection coefficient. The maximum and minimum hydrodynamic efficiency occur when the system is arranged at the wave nodes and antinodes of the formed standing wave field. Lower wave reflection and better wave power extraction can be achieved by properly adjusting the chamber drafts and breadths.
AKT-dependent nuclear localization of EPRS1 activates PARP1 in breast cancer cells
Authors: Zin Isaac , China Arnab , Khan Krishnendu , Nag Jeetendra K. , Vasu Kommireddy , Deshpande Gauravi M. , Ghosh Prabar K. , Khan Debjit , Ramachandiran Iyappan , Ganguly Shinjini , Tamagno Ilaria , Willard Belinda , Gogonea Valentin , Fox Paul L.
Published: July 2024

Glutamyl-prolyl-tRNA synthetase (EPRS1) is a bifunctional aminoacyl-tRNA-synthetase (aaRS) essential for decoding the genetic code. EPRS1 resides, with seven other aaRSs and three noncatalytic proteins, in the cytoplasmic multi-tRNA synthetase complex (MSC). Multiple MSC-resident aaRSs, including EPRS1, exhibit stimulus-dependent release from the MSC to perform noncanonical activities distinct from their primary function in protein synthesis. Here, we show EPRS1 is present in both cytoplasm and nucleus of breast cancer cells with constitutively low phosphatase and tensin homolog (PTEN) expression. EPRS1 is primarily cytosolic in PTEN-expressing cells, but chemical or genetic inhibition of PTEN, or chemical or stress-mediated activation of its target, AKT, induces EPRS1 nuclear localization. Likewise, preferential nuclear localization of EPRS1 was observed in invasive ductal carcinoma that were also P-Ser
473
-AKT
+
. EPRS1 nuclear transport requires a nuclear localization signal (NLS) within the linker region that joins the catalytic glutamyl-tRNA synthetase and prolyl-tRNA synthetase domains. Nuclear EPRS1 interacts with poly(ADP-ribose) polymerase 1 (PARP1), a DNA-damage sensor that directs poly(ADP-ribosyl)ation (PARylation) of proteins. EPRS1 is a critical regulator of PARP1 activity as shown by markedly reduced ADP-ribosylation in EPRS1 knockdown cells. Moreover, EPRS1 and PARP1 knockdown comparably alter the expression of multiple tumor-related genes, inhibit DNA-damage repair, reduce tumor cell survival, and diminish tumor sphere formation by breast cancer cells. EPRS1-mediated regulation of PARP1 activity provides a mechanistic link between PTEN loss in breast cancer cells, PARP1 activation, and cell survival and tumor growth. Targeting the noncanonical activity of EPRS1, without inhibiting canonical tRNA ligase activity, provides a therapeutic approach potentially supplementing existing PARP1 inhibitors.
The receptor-like kinase ARK controls symbiotic balance across land plants
Authors: Sgroi Mara , Hoey David , Medina Jimenez Karina , Bowden Sarah L. , Hope Matthew , Wallington Emma J. , Schornack Sebastian , Bravo Armando , Paszkowski Uta
Published: July 2024

The mutualistic arbuscular mycorrhizal (AM) symbiosis arose in land plants more than 450 million years ago and is still widely found in all major land plant lineages. Despite its broad taxonomic distribution, little is known about the molecular components underpinning symbiosis outside of flowering plants. The ARBUSCULAR RECEPTOR-LIKE KINASE (ARK) is required for sustaining AM symbiosis in distantly related angiosperms. Here, we demonstrate that ARK has an equivalent role in symbiosis maintenance in the bryophyte
Marchantia paleacea
and is part of a broad AM genetic program conserved among land plants. In addition, our comparative transcriptome analysis identified evolutionarily conserved expression patterns for several genes in the core symbiotic program required for presymbiotic signaling, intracellular colonization, and nutrient exchange. This study provides insights into the molecular pathways that consistently associate with AM symbiosis across land plants and identifies an ancestral role for
ARK
in governing symbiotic balance.
The pathogenic T42A mutation in SHP2 rewires the interaction specificity of its N-terminal regulatory domain
Authors: van Vlimmeren Anne E. , Voleti Rashmi , Chartier Cassandra A. , Jiang Ziyuan , Karandur Deepti , Humphries Preston A. , Lo Wan-Lin , Shah Neel H.
Published: July 2024

Mutations in the tyrosine phosphatase Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) are associated with a variety of human diseases. Most mutations in SHP2 increase its basal catalytic activity by disrupting autoinhibitory interactions between its phosphatase domain and N-terminal SH2 (phosphotyrosine recognition) domain. By contrast, some disease-associated mutations located in the ligand-binding pockets of the N- or C-terminal SH2 domains do not increase basal activity and likely exert their pathogenicity through alternative mechanisms. We lack a molecular understanding of how these SH2 mutations impact SHP2 structure, activity, and signaling. Here, we characterize five SHP2 SH2 domain ligand-binding pocket mutants through a combination of high-throughput biochemical screens, biophysical and biochemical measurements, and molecular dynamics simulations. We show that while some of these mutations alter binding affinity to phosphorylation sites, the T42A mutation in the N-SH2 domain is unique in that it also substantially alters ligand-binding specificity, despite being 8 to 10 Å from the specificity-determining region of the SH2 domain. This mutation exerts its effect on sequence specificity by remodeling the phosphotyrosine-binding pocket, altering the mode of engagement of both the phosphotyrosine and surrounding residues on the ligand. The functional consequence of this altered specificity is that the T42A mutant has biased sensitivity toward a subset of activating ligands and enhances downstream signaling. Our study highlights an example of a nuanced mechanism of action for a disease-associated mutation, characterized by a change in protein–protein interaction specificity that alters enzyme activation.
The acquisition of generic null subjects under the Borer-Chomsky conjecture
Authors: Bertolino Karina
Published: July 2024

This chapter examines how Brazilian Portuguese (BP)-speaking children acquire a critical property
associated with partial null-subject languages, generic null subjects. The purpose is to investigate whether the data
about the acquisition of generic null subjects are compatible with the idea that parametric variation is caused by the
cross-linguistic distribution of features in functional heads (known as the Borer-Chomsky conjecture). To acquire the
distribution of (null) subjects, the child should pay close attention to ϕ-features on T and D.
Studies have shown that children become sensitive to the presence of verbal inflections and determiners before their
first words (Dye et al., 2019), which leads to the prediction that children
should not show evidence of parameter misssetting. We found that generic null subjects emerge as early as 1;9 in BP,
which is consistent with the prediction of early parameter setting. However, generic null subjects did not appear
frequently in spontaneous production and they increase as the child grows older. As generic null subjects are used to
talk about rules, patterns and generalizations, not about specific individuals, the production of generic null
subjects increases as children’s conversational topics become less egocentric.
Quantifier comprehension in Brazilian Portuguese and the extra-object visual effect
Authors: Rodrigues Erica , Forster Renê , Sicuro Corrêa Letícia
Published: July 2024

Universal quantifiers are complex for children to comprehend, and over-exhaustive errors can occur
even with adults in sentence-picture verification tasks. This paper addresses visual design factors that may explain
these difficulties. We examine what we call the “single extra object attraction hypothesis” (SEOH), according to which
the visual prominence of a uniquely unpaired extra object compromises attentional resources during these tasks. We
manipulated the type of extra-object – single or double – in an eye-tracking experiment with adult speakers of
Brazilian Portuguese. Contrary to the SEOH prediction, double objects gave rise to earlier and longer fixations than
single objects. There was no difference in accuracy. We discuss the implications of these results for developmental
research.
Between source language constructions and target language expectations
Authors: Oster Ulrike , Tello Isabel
Published: July 2024

This paper is situated within Cognitive Translation Studies (CTS). It follows Halverson’s Gravitational Pull
Hypothesis (2003, 2010, 2017, 2024), a framework that explains the
translation process and its outcome by invoking the cognitive mechanisms of the bilingual mind. The paper adopts the cognitive,
multi-method approach of the GPH to describe and compare the use of Spanish passive constructions in a multilingual comparable
corpus of translated and non-translated texts. In doing so, it pushes the boundaries of the model by: (a) following an
onomasiological rather than a semasiological approach; (b) focusing on constructions rather than lexical items; and (c) explicitly
incorporating the aspect of translator socialisation into the hypothesis formulation, thereby taking into account the situatedness
of translation. The results provide evidence in support of the GPH, as salience of a construction in the source or target language
leads to its overrepresentation in the translated texts, and non-salience leads to its underrepresentation.
Arp2/3-dependent endocytosis ensures Cdc42 oscillations by removing Pak1-mediated negative feedback
Authors: Harrell Marcus A. , Liu Ziyi , Campbell Bethany F. , Chinsen Olivia , Hong Tian , Das Maitreyi
Published: July 2024

The GTPase Cdc42 regulates polarized growth in most eukaryotes. In the bipolar yeast Schizosaccharomyces pombe, Cdc42 activation cycles periodically at sites of polarized growth. These periodic cycles are caused by alternating positive feedback and time-delayed negative feedback loops. At each polarized end, negative feedback is established when active Cdc42 recruits the Pak1 kinase to prevent further Cdc42 activation. It is unclear how Cdc42 activation returns to each end after Pak1-dependent negative feedback. We find that disrupting branched actin-mediated endocytosis disables Cdc42 reactivation at the cell ends. Using experimental and mathematical approaches, we show that endocytosis-dependent Pak1 removal from the cell ends allows the Cdc42 activator Scd1 to return to that end to enable reactivation of Cdc42. Moreover, we show that Pak1 elicits its own removal via activation of endocytosis. These findings provide a deeper insight into the self-organization of Cdc42 regulation and reveal previously unknown feedback with endocytosis in the establishment of cell polarity.
Equivalent electrical circuits for electroacoustic MEMS design: a review
Authors: Liechti Romain
Published: July 2024

At the era of powerful computers, it is tempting to employ finite element models early in the design phase of a device. However, especially for MEMS devices, the dimensional ratios and short wavelengths compared to the device’s dimensions, along with the involvement of multiple physics, can necessitate complex and computationally intensive models, making them impractical for optimization processes. Hence, reduced order models, like the lumped element model, are often preferred as they accurately represent complex system behaviour within a defined frequency range. This review explores the use of lumped element models and their corresponding electrical equivalent circuits for simulating MEMS electro-acoustic devices, offering insights into their diverse applications within this specific domain.
Morphology of films deposited on the sidewall during the Bosch process using C4F8 plasmas
Authors: Nonaka Tomoyuki , Takahashi Kazuo , Uchida Akimi , Tsuji Osamu
Published: July 2024

In the Bosch process, C4F8 plasmas are used to deposit passivation films. In this study, the passivation films were deposited in micro-scale trenches by changing the C4F8 flow rate, ICP power, and pressure, and their cross sections were observed by scanning electron microscopy. The results showed that the morphology of the passivation film and its relative deposition rate at each depth varied depending on the plasma discharge conditions. There is a correlation between the C–CF
x
bond content and the morphology of passivation films, with high C–CF
x
bond content resulting in smooth morphology and low C–CF
x
bond content resulting in a rough morphology. Furthermore, it was found that ion bombardment reduced the roughness of the passivation film. Through these experiments, we also found the possibility of controlling the deposition rate of the passivation film at each trench depth by adjusting the plasma discharge conditions.
Effect of Ar-ion irradiation on electrical transport of WS2 monolayer
Authors: Luhar Bhumit , Thakur Deepa , Naik B Raju , Balakrishnan Viswanath
Published: July 2024

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

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

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

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

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

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

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

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

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

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

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

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

The 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.