bluuebunny/crossref_metadata_2025 huggingface dataset:
Validity of Stokes' hypothesis for near-continuum hypersonic flows
Authors: Valentini Paolo , Grover Maninder S. , Bisek Nicholas J.
Published: May 2024

The alternative interpretation of Stokes' hypothesis provided by Buresti [Acta Mech. 226, 3555–3559 (2015)] is investigated by an analysis of a near-continuum, hypersonic flow of oxygen over a double cone obtained from a large-scale direct simulation Monte Carlo computation. We show that for molecular oxygen, which has comparable bulk and shear viscosity coefficients, the difference between mechanical and thermodynamic pressure is negligible throughout most of the flow. This result justifies neglecting viscous stresses in the normal stress tensor associated with fluid particle dilatation, as is often done in continuum descriptions of compressible flows. The violation of the revisited Stokes' hypothesis was only observed in highly nonequilibrium regions of the flow (shocks and strong expansions) and wherever non-continuum effects become significant. For nonequilibrium flows of gases with large bulk viscosity relative to their shear viscosity, the revisited Stokes' assumption may still breakdown and requires further investigation.
Stochastic models in the under-resolved simulations of spray formation during high-speed liquid injection
Authors: Oruganti S. K. , Gorokhovski M. A.
Published: May 2024

In the under-resolved simulation of the high-speed liquid injection into stagnant air, the attention in subgrid-scale models is focused on events of intense gradients of the velocity in turbulent flow, i.e., on effects of intermittency. Three typical flows are considered—the in-nozzle flow, primary atomization zone, and secondary atomization of spray droplets. In the simulation of the first two flows, the filtered Navier–Stokes equations are forced by stochastic processes with properties which incorporate the statistical physics of fluid acceleration at the high Reynolds number—in this way we update the under-resolved acceleration. In the case of in-nozzle flow, the proposed stochastic subgrid acceleration model is combined with wall-damping function, and the ability in prediction of the velocity statistics is demonstrated. In the simulation of primary atomization, the approach with stochastic subgrid acceleration is combined with the volume of fluid method. This leads to intensification of the interface dynamics, resulting in additional corrugation, with more intense shearing and stretching of liquid structures are observed. Thereby, the experimental profiles of the time-averaged liquid volume fraction distribution for four different axial locations are rather well predicted. The secondary atomization of droplets is simulated by a new stochastic model for the breakup rate along the droplet path. To this end, the breakup rate is expressed as a function of turbulent viscous dissipation which evolves along the droplet path according to the proposed stochastic process. Preliminary assessment performed against the recent experiments shows the correct predictability of this model and its low sensibility to the grid density.
Anisotropic quasi-static permittivity of rare-earth scandate single crystals measured by terahertz spectroscopy
Authors: Taherian Afrouz , Cooke Jacqueline , Schubert Mathias , Sensale-Rodriguez Berardi
Published: May 2024

We report the real-valued static and complex-valued quasi-static anisotropic permittivity parameters of rare-earth scandate orthorhombic single crystal GdScO3 (GSO), TbScO3 (TSO), and DyScO3 (DSO). Employing continuous-wave terahertz spectroscopy (0.2–1 THz), the complex permittivity was extracted using an anisotropic ambient-film-ambient model. Data obtained from multiple samples of the same oxides and different surface cuts were analyzed simultaneously. The zero-frequency limit of the modeled data indicates that at room temperature the real part of the dielectric tensor components for GSO are ɛa = 22.7, ɛb = 19.3, and ɛc = 28.1; for DSO, ɛa = 20.3, ɛb = 17.4, and ɛc = 31.1; and for TSO, ɛa = 21.6, ɛb = 18.1, and ɛc = 30.3, with a, b, and c crystallographic axes constituting the principal directions for the permittivity tensor. These results are in excellent agreement with expectations from theoretical computations and with scarcely available data from previous experimental studies. Furthermore, our results evidence a noticeable attenuation, which increases with frequency, and are very significant especially at the higher frequency end of the measurement and along the c-direction in all samples. We suggest the attenuation is most likely caused by the onset of absorption due to long-wavelength active optical phonon modes. These results are important for electronic and potential sub-terahertz applications (e.g., quarter-wave plate) benefiting from the large index contrast along different directions in these materials.
Thermoelectric properties and thermal transport in two-dimensional GaInSe3 and GaInTe3 monolayers: A first-principles study
Authors: Nautiyal Himanshu , Scardi Paolo
Published: May 2024

We here report the electronic structure calculation of GaInSe3 and GaInTe3 monolayers with the P3m1 (no. 156) space group. The electronic structure and thermoelectric properties of the monolayers are calculated through the Vienna Ab initio Simulation Package and BoltzTraP2 codes. The dynamic and thermodynamic stabilities were verified by calculating their phonon spectra and simulating ab initio molecular dynamics. The monolayers were found to have a direct bandgap, with both PBE + SOC and HSE06 + SOC potentials. The lattice thermal conductivity of GaInTe3 monolayer calculated using Phono3py code shows ultra-low values due to enhanced phonon–phonon scattering. Combining electrical and thermal transport, the values have been evaluated. Importantly, the p-type GaInTe3 has excellent thermoelectric properties at 700 K, with a zT value of 2, indicating that the p-type GaInTe3 has potential application in the field of thermoelectricity.
Direct numerical simulation of compressible turbulent channel flows over porous boundaries
Authors: Zhou Zisong , Huang Wei-Xi , Xu Chun-Xiao
Published: May 2024

The impact of porous boundaries on skin friction and heat transfer in compressible turbulent channel flows is explored through direct numerical simulations. Utilizing the volume-averaged Navier–Stokes equations for the porous media, we examine flows at Mach numbers Mb=0.3 and Mb=1.5, with friction Reynolds numbers ranging from 176 to 220, across three permeability levels: 0 (impermeable), 1.6×10−5, and 1.0×10−4. Our findings reveal a dual impact of porous boundaries on skin friction: a direct reduction due to averaged slip velocity at the interface and an indirect increase from amplified Reynolds shear stress due to enhanced wall-normal permeability. This permeability weakens the wall-blocking effect, leading to intensified wall-normal velocity fluctuations and consequently higher Reynolds stress. Additionally, the Mach number significantly influences flow structures, particularly at higher permeabilities, where it disrupts near-wall streaks at Mb=0.3 but has a diminished effect at Mb=1.5. Thermal analysis confirms the validity of the generalized Reynolds analogy for the mean temperature in these flows, with the turbulent Prandtl number approximating 1, in line with the strong Reynolds analogy. Moreover, a strong spatial correlation between heat flux and wall shear stress fluctuations underscores the intertwined dynamics of momentum and thermal transport at the porous–fluid interface.
Effects of compressibility on Richtmyer–Meshkov instability of heavy/light interface
Authors: Li Jiaxuan , Chen Chenren , Zhai Zhigang , Luo Xisheng
Published: May 2024

Experimental and numerical studies on the evolution of shock-accelerated SF6/air interface with small initial amplitude are conducted. The effect of compressibility on the early development of perturbation is highlighted by varying shock intensity and fluid properties. The startup process is analyzed when rarefaction waves are reflected and the characteristic time of the startup process is provided. The relationship between the phase inversion process and the startup process under different incident shock strengths is clarified. According to the startup time, a new start point for normalization is given, which can better normalize the amplitude growth at the early stage. In addition, the effects of incident shock strength and physical properties of fluids on the linear growth rate are highlighted through numerical simulations. The incompressible linear model loses validity when the incident shock is strong, and the existing rotational model is verified to provide excellent predictions under any shock strengths. The decrease in adiabatic exponent of the heavy fluid or the increase in adiabatic exponent of the light fluid can reduce the linear growth rate. As the absolute value of Atwood number increases, the adiabatic exponent of the heavy fluid has a more significant effect on the linear growth than that of the light fluid.
Crystal orientation-dependent superconductivity in titanium nitride films
Authors: Zhang Shan , Bi Jiachang , Tu Yubing , Zhou Zekun , Han Tao , Yuan Xiaoqiu , Zhang Zongyuan , Hou Xingyuan , Cao Yanwei , Shan Lei
Published: May 2024

High-quality titanium nitride (TiN) films with different crystal orientations (001, 110, and 111) obtained under the same growth conditions are systematically investigated by both ultra-low temperature scanning tunneling microscope/spectroscopy and transport experiments. Our results reveal that all of them are conventional type-II superconductors, which exhibit spatially homogeneous superconducting properties. The superconductivity is uniform between surface and bulk. Intriguingly, the TiN (111) film has the highest transition temperature (Tc) but the lowest upper critical field (Hc2). This crystal orientation-dependent superconductivity could be explained by the fact that TiN (001) and TiN (110) films are dirtier than TiN (111). Our results suggest that (111)-oriented TiN is superior to design certain superconducting devices, including Josephson junction devices. The crystallographic orientation could offer an effective controlling parameter for designing TiN-based superconducting devices.
Identification of network interactions from time series data: An iterative approach
Authors: Singhal Bharat , Li Shicheng , Li Jr-Shin
Published: May 2024

The first step toward advancing our understanding of complex networks involves determining their connectivity structures from the time series data. These networks are often high-dimensional, and in practice, only a limited amount of data can be collected. In this work, we formulate the network inference task as a bilinear optimization problem and propose an iterative algorithm with sequential initialization to solve this bilinear program. We demonstrate the scalability of our approach to network size and its robustness against measurement noise, hyper-parameter variation, and deviations from the network model. Results across experimental and simulated datasets, comprising oscillatory, non-oscillatory, and chaotic dynamics, showcase the superior inference accuracy of our technique compared to existing methods.
Impact of bull age, sperm processing, and microclimatic conditions on the viability and DNA integrity of cryopreserved bovine sperm
Authors: Cinar Burcu , Bollwein Heinrich , Siuda Mathias , Lautner Matthias , Leiding Claus , Malama Eleni
Published: May 2024

Context Seasonal microclimatic fluctuations can cause changes in sperm quality even in dairy bulls bred under temperate climate. These changes can vary between sires of different age and affect sperm freezability. Aims We aimed to evaluate the modulating effect of bull age and equilibration time before freezing on the seasonal pattern of sperm viability and DNA integrity post-thaw. Methods In the frame of systematic sperm quality control, we assessed the integrity of sperm plasma membrane and acrosome (PMAI) in 15,496 cryopreserved bovine batches, and the percentage of sperm with high DNA fragmentation index (%DFI) after 0 h and 3 h incubation at 38°C post-thaw (3 h) in 3422 batches. Semen was equilibrated for 24 h before freezing if collected on Monday or Wednesday and 72 h if produced on Friday. We investigated the effect of season, bull age, equilibration, and temperature-humidity index (THI) on the day of semen collection on sperm traits using mixed-effects linear models. Key results PMAI and %DFI (0 h and 3 h) deteriorated with increasing THI. The effect of THI on %DFI was detected with a 30-day time lag. Seasonal fluctuations of sperm quality were similar between young, mature, and older sires. Prolonged equilibration did not affect PMAI but was linked to elevated %DFI (3 h) in summer. Conclusions Extending equilibration from 24 to 72 h is compatible with commercial standards of bovine sperm quality post-thaw; however, it could interfere with the seasonal pattern of the latter. Implications Systematic monitoring of bovine sperm quality enables the prompt detection of stress factors related to microclimate and semen processing.
Unravelling male advertisement call variability in the brown tree frog (Litoria ewingii) complex by using citizen science
Authors: Elliott-Tate Jessica , Rowley Jodi J. L.
Published: May 2024

In the face of global biodiversity declines, conservation measures are urgently needed. However, our lack of knowledge on species’ diversity, distributions and population trends presents a major obstacle, particularly for morphologically cryptic species. Field surveys to gather this information present a logistical challenge, but the rapid rise of citizen science presents a new opportunity, generating huge volumes of data rapidly across a species’ range. We use data from a national citizen-science project to document the distribution and advertisement call variability in a group of five morphologically conserved treefrogs. Using 542 male advertisement calls across the entire range of five species, we found considerable levels of acoustic variation both among and within species. Note shape, notes per call and positions of the longest and shortest notes were most useful to delineate species. Our research will assist in species delineation and identification in the field and form the basis for a more accurate understanding of species diversity and distributions in the brown tree frog complex. We also demonstrated the utility of citizen science in documenting species distributions and diversity.
Unveiling the role of proton concentration in dinuclear metal complexes for boosting photocatalytic CO
2
reduction
Authors: Wang Hui-Feng , Wang Hong-Juan , Zhong Di-Chang , Lu Tong-Bu
Published: May 2024

The reaction kinetics of photocatalytic CO
2
reduction is highly dependent on the transfer rate of electrons and protons to the CO
2
molecules adsorbed on catalytic centers. Studies on uncovering the proton effect in catalysts on photocatalytic activity of CO
2
reduction are significant but rarely reported. In this paper, we, from the molecular level, revealed that the photocatalytic activity of CO
2
reduction is closely related to the proton availability in catalysts. Specifically, four dinuclear Co(II) complexes based on Robson-type ligands with different number of carboxylic groups (–
n
COOH;
n
= 0, 2, 4, 6) were designed and synthesized. All these complexes show photocatalytic activity for CO
2
reduction to CO in a water-containing system upon visible-light illumination. Interestingly, the CO yields increase positively with the increase of the carboxylic-group number in dinuclear Co(II) complexes. The one containing –6COOH shows the best photocatalytic activity for CO
2
reduction to CO, with the TON value reaching as high as 10,294. The value is 1.8, 3.4, and 7.8 times higher than those containing –4COOH, –2COOH, and –0COOH, respectively. The high TON value also makes the dinuclear Co(II) complex with –6COOH outstanding among reported homogeneous molecular catalysts for photocatalytic CO
2
reduction. Control experiments and density functional theory calculation indicated that more carboxylic groups in the catalyst endow the catalyst with more proton relays, thus accelerating the proton transfer and boosting the photocatalytic CO
2
reduction. This study, at a molecular level, elucidates that more carboxylic groups in catalysts are beneficial for boosting the reaction kinetics of photocatalytic CO
2
reduction.
A PAK family kinase and the Hippo/Yorkie pathway modulate WNT signaling to functionally integrate body axes during regeneration
Authors: Doddihal Viraj , Mann Frederick G. , Ross Eric J. , McKinney Mary C. , Guerrero-Hernández Carlos , Brewster Carolyn E. , McKinney Sean A. , Sánchez Alvarado Alejandro
Published: May 2024

Successful regeneration of missing tissues requires seamless integration of positional information along the body axes. Planarians, which regenerate from almost any injury, use conserved, developmentally important signaling pathways to pattern the body axes. However, the molecular mechanisms which facilitate cross talk between these signaling pathways to integrate positional information remain poorly understood. Here, we report a
p21-activated kinase
(
smed-pak1
) which functionally integrates the anterior–posterior (AP) and the medio-lateral (ML) axes.
pak1
inhibits WNT/β-catenin signaling along the AP axis and, functions synergistically with the β-catenin-independent WNT signaling of the ML axis. Furthermore, this functional integration is dependent on
warts
and
merlin
—the components of the Hippo/Yorkie (YKI) pathway. Hippo/YKI pathway is a critical regulator of body size in flies and mice, but our data suggest the pathway regulates body axes patterning in planarians. Our study provides a signaling network integrating positional information which can mediate coordinated growth and patterning during planarian regeneration.
La gramaticalización de los futuros y condicionales en el navarroaragonés de los siglos xiii y xiv
Authors: Primerano Antoine , Bouzouita Miriam
Published: May 2024

This paper aims to partially verify the hypothesis following which the grammaticalisation of the Ibero-Romance future and conditional tenses unfolded earlier in the (north-)eastern peninsular varieties before spreading to the central and western part of the Iberian territory through language and dialect contact. For this purpose, we will contrastively examine the distribution of futures and conditionals in Navarro-Aragonese and Castilian for the 13th and 14th century, more specifically the variation between the so-called synthetic verb forms with postverbal object pronouns and the analytic forms with mesoclitic pronouns, including the morpho-syntactic factors that favour the use of the former. It is shown that Navarro-Aragonese seems to exhibit a higher frequency of use of the synthetic forms with postverbal pronouns, especially with syncopated verbs, conditionals and a following non-finite verb form.
Research on partial discharge detection based on distributed optical fiber acoustic sensor
Authors: Sun Yuwei , Lv Anqiang , Xie Zhiyuan , Kong Yan
Published: May 2024

Distributed acoustic sensors (DASs) have the advantage of long-distance and distributed monitoring of vibration signals. However, there are few studies on the application of DAS for partial discharge (PD) monitoring of power equipment. There is also a lack of related theoretical and methodological studies. In this paper, the DAS-measured phase signals are theoretically analyzed from the frequency and energy perspectives, and the method of PD broadband signal coverage using spectrum and energy accumulation is proposed. Fiber optic rings are employed for the detection of PD signals, and the precise localization of these signals is achieved by calculating the DAS energy spectrum. The fiber optic ring is wrapped around the cable joint to achieve the detection and locating of the PD signal. The results indicate that the use of a fiber optic ring can realize the sensitive detection and locating of PD. The signal strength is maximum when the length of the fiber ring is equal to the spatial resolution of DAS. The sensitivity of PD detection in cable joints can reach 40 pC, and the simultaneous detection and localization of PD at different locations can be realized. The research can provide support for theoretical and experimental for the monitoring of PD in power equipment.
Quantum–classical correspondence in spin–boson equilibrium states at arbitrary coupling
Authors: Cerisola F , Berritta M , Scali S , Horsley S A R , Cresser J D , Anders J
Published: May 2024

The equilibrium properties of nanoscale systems can deviate significantly from standard thermodynamics due to their coupling to an environment. We investigate this here for the θ-angled spin–boson model, where we first derive a compact and general form of the classical equilibrium state including environmental corrections to all orders. Secondly, for the quantum spin–boson model we prove, by carefully taking a large spin limit, that Bohr’s quantum–classical correspondence persists at all coupling strengths. This shows, for the first time, the validity of the quantum–classical correspondence for an open system and gives insight into the regimes where the quantum system is well-approximated by a classical one. Finally, we provide the first classification of the coupling parameter regimes for the spin–boson model, from weak to ultrastrong, both for the quantum case and the classical setting. Our results shed light on the interplay of quantum and mean force corrections in equilibrium states of the spin–boson model, and will help draw the quantum to classical boundary in a range of fields, such as magnetism and exciton dynamics.
On the universality of Sn-equivariant k-body gates
Authors: Kazi Sujay , Larocca Martín , Cerezo M
Published: May 2024

The importance of symmetries has recently been recognized in quantum machine learning from the simple motto: if a task exhibits a symmetry (given by a groupG), the learning model should respect said symmetry. This can be instantiated viaG-equivariant quantum neural networks (QNNs), i.e. parametrized quantum circuits whose gates are generated by operators commuting with a given representation ofG. In practice, however, there might be additional restrictions to the types of gates one can use, such as being able to act on at mostkqubits. In this work we study how the interplay between symmetry andk-bodyness in the QNN generators affect its expressiveness for the special case ofG=Sn, the symmetric group. Our results show that if the QNN is generated by one- and two-bodySn-equivariant gates, the QNN is semi-universal but not universal. That is, the QNN can generate any arbitrary special unitary matrix in the invariant subspaces, but has no control over the relative phases between them. Then, we show that in order to reach universality one needs to includen-body generators (ifnis even) or(n−1)-body generators (ifnis odd). As such, our results brings us a step closer to better understanding the capabilities and limitations of equivariant QNNs.
Multiple solitons with fission and multi waves interaction solutions of a (3+1)-dimensional combined pKP-BKP integrable equation
Authors: Saifullah Sayed , Ahmad Shabir , Ali Khan Meraj , ur Rahman Mati
Published: May 2024

The potential Kadomtsev-Petviashvili (pKP) equation delineates the development of small-amplitude, nonlinear, long waves characterized by a gradual variation in the transverse coordinate. The B-type KP equation outlines the relationships among exponentially localized shapes and was employed as a representation for shallow water waves and plasma physics. In this paper, we consider the combined pKP-BKP integrable equation. We discuss the multiple solitons of a newly proposed (3+1)-dimensional combined pKP-BKP integrable equation. We use the Hirota bilinear (HB) form of the considered equation to deduce fission process in higher order solitons with different orders. Moreover, the breather dynamics and its interaction with other solitons are investigated via HB. The lump solution and its interaction with first order and fourth order kink soliton is studied.
Revealing the high-performance of a novel Ge-Sn-Based perovskite solar cell by employing SCAPS-1D
Authors: Ashrafi Noor–E- , Miah Md Helal , Rahman Md Bulu , Aminul Islam Mohammad , Khandaker Mayeen Uddin
Published: May 2024

In this study, a novel Ge-Sn based perovskite solar cell (PSC) with the structure FTO/WS2/ FA0.75MA0.25Sn0.95Ge0.05I3/MoO3/Ag has been designed and thoroughly analyzed employing SCAPS-1D. Drawing attention from the work of Ito et al where a similar perovskite-based PSC displayed a poor performance of ∼ 4.48% PCE, in which a large conduction band offset (CBO) acts as a critical factor contributing to interfacial recombination and device deterioration. To address this issue, we presented WS2 as an electron transport layer (ETL) along with MoO3 as a hole transport layer (HTL), both possessing compatible CBO and valence band offset (VBO) with perovskite material. Through systematic simulations and optimizations, remarkable improvements in the PSC’s performance have been acquired, getting a power conversion efficiency (PCE) of 18.97%. The optimized structure involved a 50 nm MoO3 HTL, 350 nm FA0.75MA0.25Sn0.95Ge0.05I3 light-harvesting layer (LHL), and a 50 nm WS2 ETL. Bulk defect densities for the LHL and ETL were optimized to 1 × 1015 cm−3 and 1 × 1018 cm−3, respectively, significantly superior values than that of reported value in the literature. Particularly, the tolerable defect density of ETL has increased 1000 times more than the published literature. The interfacial tolerable trap density for MoO3/perovskite increased from 1 × 1014 cm−2 to 1 × 1016 cm−2. The study also explored the impact of defects on quantum efficiency, revealing a severe negative influence beyond a perovskite bulk defect density of 1 × 1017 cm−3. Light intensity analysis demonstrated a correlation between incident light reduction and device performance decay. Capacitance–Voltage (C-V) and Mott–Schottky (M-S) have been analyzed during the study. Finally, the total recombination of the optimized device concerning thickness has been analyzed along with the dark J-V characteristics. The comprehensive insights gained from this work are anticipated to accelerate the fabrication of mixed Ge-Sn based PSCs with improved efficiency, paving the way for commercialization in the photovoltaic industry.
Microstructure and cyclic hardening/softening behavior of laser welded high strength steel joints under asymmetrical cyclic loading
Authors: Zhao Xinlong , Yang Shanglei , Bi Junhang , Tian Jiawei , Li Yanlei , Peng Zeng
Published: May 2024

The cyclic behavior of materials under load and its influence on the mechanical properties of materials have always been the focus of engineering research. In this study, high strength steel was successfully welded by laser welding. The microstructure of each region of the high strength steel DP590 post-welding was meticulously analyzed. Additionally, 500 cycles of low-cycle fatigue tests of laser welded high strength steel were carried out by using asymmetric stress control method. After fatigue test, tensile test shall be carried out on some samples. Under the specific combination of mean stress and stress amplitude, compare the specimens that have not been fatigue tested with those that have been fatigue tested, the change of properties of laser welded high strength steel joint under asymmetric cyclic load was analyzed. The results showed that, due to cyclic hardening, the tensile strength of the sample increased to 601 MPa and the yield strength to 325 MPa. Compared with the original sample, the tensile strength and yield strength of the sample after asymmetric cycling had increased by 8.65% and 31.3%, respectively.
Comparative study between oxide/soft ferrite, oxide/hard ferrite, and soft/hard ferrite nanocomposites: structural, electrical, and magnetic properties
Authors: Farhat S , Awad R , Bitar Z
Published: May 2024

Three binary nanocomposites (NCs): (0.5NiO/0.5Ni0.5Zn0.5Fe2O4), (0.5NiO/0.5BaFe12O19), and (0.5Ni0.5Zn0.5Fe2O4/0.5BaFe12O19) were prepared using the co-precipitation method followed by the wet ball-milling technique. X-ray diffraction analysis showed the production of NiO and Ni0.5Zn0.5Fe2O4 single phases, while the α-Fe2O3 secondary phase appeared in the BaFe12O19 and the 0.5Ni0.5Zn0.5Fe2O4/0.5BaFe12O19 nanocomposite. The transmission electron microscopy investigation and the selected area electron diffraction demonstrated the presence of the nanocomposites’ constituent phases. x-ray photoelectron spectroscopy identified the oxidation states found in the prepared samples (Ba2+, Ni2+, Ni3+, Zn2+, Fe3+, and O2−). The bandgap values

(
E

g

)

of the nanocomposites are in the range between 2.79 and 3.66 eV, which indicates their semiconductor nature. The DC conductivity experiment confirmed the semiconducting nature of all samples, and the activation energies (

E

aH

) and (

E

aL

) at high and low-temperature regions, respectively, were calculated from the Arrhenius equation. According to the vibrating sample magnetometer, the NCs exhibited ferromagnetic (FM) as showed by the M-H loops. In the oxide/soft ferrite NC, the dM/dH curve indicated strong exchange coupling interactions, while the hard and the soft magnetic phases in the oxide/hard ferrite and the soft/hard ferrite NCs were weakly exchanged coupled. Significant uses had been found for each of the three nanocomposites according to their constituent phases and properties.
Remote operation of the DIII-D National Fusion Facility
Authors: Schissel D.P. , Cho E. , Flanagan S. , Garcia F. , Liu C. , Margo M. , Nguyen J. , Nguyen P. , Parker C. , Penaflor B. , Pederson T. , Piglowski D. , Rivas E. , Shapov R. , Shen H. , Short B. , Waddell T. , Kalling R.
Published: May 2024

Full remote scientific operation of the DIII-D National Fusion Facility is now possible through significant advances in the computer science hardware and software infrastructure made over the last decade. Capabilities around information visualization, data movement, and communication have all been enhanced. The level of capability deployed to remotely operate DIII-D required an infrastructure advancement over what had previously been achieved in the fusion community. The large quantity of real-time data that is automatically displayed on DIII-D’s control room screens can now be visualized by remote participants via web-based applications. New audio/video solutions using the VoIP and instant messaging application Discord have been implemented to mimic the dynamic and ad-hoc scientific conversations that are critical in successfully operating an experimental campaign. Discord’s ability for a user to rapidly move between audio channels, text with images, and share screens is a significant enhancement over traditional videoconferencing tools. In addition, multiple combinations of broadcast audio are made available via a web-based application to allow remote participants to simultaneously listen to general announcements/sounds while conducting their own specific conversations. Secure methodologies have been put into place to allow remote control of hardware including DIII-D’s plasma control system application. Secure methods also included the ability of the on-site team to closely coordinate their work with remote team members which has been enhanced through extensions to the wireless network and the use of tablet computers for audio/video/screen sharing. However, no amount of software can fully replace the need for ‘hands on hardware.’ This infrastructure was severely stress tested during the COVID-19 pandemic where occupancy of the DIII-D control room was restricted. Operational efficiency during the pandemic, measured in discharges per hour, remained high (3.8 ± 0.8) compared to values obtained pre-pandemic (3.7 ± 0.8).
Silicon/Silver nanocomposite-based surface-enhanced Raman spectroscopy (SERS) biosensor for ultrasensitive direct detection of deafness mutations in real system
Authors: Safadi Arwa Al , Ramachandran Krithikadevi , Tlili Abdelaziz , Daoudi Kais
Published: May 2024

Surface-enhanced Raman scattering (SERS) is a promising emerging, highly sensitive technique for detecting biological samples. The current research aims to bring an effortless biosensor-based approach to detect and discriminate DNA mutations with their fingerprints for each deafness mutation within the GJB2 (gap junction beta 2) gene. Therefore, we developed silver (Ag) modified silicon-based SERS sensing platform to directly screen GJB2 gene mutations for UAE patients with hereditary hearing loss (HL). The prepared AgNPs@Si biosensor was utilized for establishing a silicon-based SERS biosensing protocol for further analyses toward label-free DNA deafness mutations screening. Furthermore, the comparative studies demonstrated the viability of the developed sensor to distinguish between the normal/mutant samples in the real-time system by investigating the DNA assignments and the peaks intensity. Noticeably, under 785 nm laser excitation distinguishable Raman peaks for cytosine bands (C) are enriched with normal DNA (DMF-34) at 780 cm−1, 1450 cm−1 and 1590 cm−1 whereas with the single nucleotide deletion of cytosine band for the mutant DNA correspondingly predicted with Quenched intensities at the parallel Raman peak positions. The sensitivity studies portrayed the limit of detection to be 1 fg/μL. Further their reproducibility studies evaluation conveyed with low values of % RSD as 10. By the end of this study, we expected to update the mutational profile of the GJB2 gene in the UAE population using the advanced simple SERS-based technique for further supplemental applications in terms of genetic counseling and prenatal diagnosis.
Effect of Heat Treatments on Microstructure and Mechanical Properties of Fe-Mn-Ni-Al-Gd Shape Memory Alloy
Authors: Mustafa Faisal , Egilmez Mehmet , Abuzaid Wael , El-Khatib Sami
Published: May 2024

There are significant scientific and industrial efforts to develop and optimize Iron-based shape memory alloys (SMA) such as FeMnNiAl for cost-sensitive applications. This alloy system shows shape memory and superelastic properties across a large temperature range. However, many studies have pointed out the need for rather complex thermo-mechanical treatments for the optimization of the SMA properties. In addition, works considering the effects of alloying on the development of microstructures that are more conducive to pseudo-elasticity in this system remain limited. Hence, systematic studies aiming at the investigation of the microstructural evolution of the FeMnNiAl(Gd) system are of great interest. In this study, solution heat treatment is done to tune the microstructure for optimum mechanical properties. The effect of phase distribution on mechanical properties is investigated at different heat treatments. Whereas cyclic heat treatment induced abnormal grain growth (AGG) in all samples, so large grains were obtained. The phase variation and elemental composition are analyzed by X-ray diffraction and Energy Dispersive Spectroscopy, respectively. The microstructure and phase distribution are observed using Scanning Electron Microscope and then related to the microhardness results. The microstructure has a good correlation with mechanical properties where the fine distribution of phases results in a higher hardness number.
Thermal Properties of Backfill Material for Underground Heat Exchange Applications
Authors: Suleiman Bashir M. , Moraitis Daniil , Abdel-Fattah Mohamed I. , Attaelmanan Atta G. , Hamdan Hamdan , Alzaylaie Marwan
Published: May 2024

We are investigating the effect of the thermal properties of backfill material on the efficiency of underground thermal energy systems. We have used aluminum to increase the thermal properties of clay-bentonite and to investigate its potential as a backfill material in underground heat exchange applications. The measurements of thermal properties were made at room temperature using the Transient Plane Source (TPS) technique. The measurements were based on an infinite homogeneous medium using different composites of aluminum and clays in amounts of aluminum concentration ranging from 6 to 25 percent of the sample’s weight. The results confirmed an overall relative increase of 170% and 135% in the thermal conductivity and diffusivity, respectively as the Al content increased by 25%. The estimated average of the thermal transmittance (U-value ) of these samples was in the range from 0.40 to 1.1 W/m2K, which was directly proportional to the relative increase in the measured properties. Our findings can be applied to underground thermal energy systems, ground source heat pumps, and solid dielectric underground transmission lines.
Effect of Gd, V, and Y Alloying on the Corrosion Properties of Fe-Mn-Ni-Al Fe-based Shape Memory Alloy
Authors: Mustafa Faisal , Ahmad Shahbaz , Hassan Arhum , Egilmez Mehmet , El-Khatib Sami , Ibrahim Taleb
Published: May 2024

Shape Memory Alloys (SMA) are widely utilized in numerous industrial applications nowadays. Significant attention has been given to Fe-based SMA in civil engineering applications due to their high strength and reasonable cost. Researchers are striving to improve the corrosion resistance of these alloys so they can be utilized in marine environments. This article focuses on the effect of Gd, V, and Y alloying on FeMnNiAl based SMA. The phases and morphological effects were characterized using X-Ray diffractometer (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). To examine the corrosive nature of the Fe-based SMA system, a potentiodynamic analysis and electrochemical impedance spectroscopy (EIS) tests were performed in 3.5% NaCl solution. Results show that the addition of Gd rare earth metal has improved the overall corrosion efficiency of Fe-based SMAs by 48%.
Electronic, Mechanical, and thermoelectric properties of Ge/Zn co-doped SnSe: first-principles calculations
Authors: Al Bouzieh N , Benkraouda M , Amrane N
Published: May 2024

Materials based on tin selenide have attracted significant attention due to their unique properties, particularly their high ZT value. This study investigates the impact of co-doping Germanium and Zinc on the electronic, mechanical, and thermoelectric properties of SnSe crystal using first-principles calculations. The doped structure demonstrated a p-type semiconducting behavior with a triclinic stable structure, which was predicted by the calculated elastic constants. Thermoelectric properties were studied for both doped and undoped systems across a wide range of carrier concentrations and temperatures. Results showed that co-doping SnSe with Ge/Zn reduced electronic thermal conductivity at room temperature while simultaneously doubling the Seebeck coefficient. This promising combination of features suggests high thermoelectric performance for the material.
Comparing the plasmon dispersion in graphene and MoS2 nanoribbons array under Electromagnetic excitation
Authors: Samy Omnia , El Moutaouakil Amine
Published: May 2024

Terahertz properties of different materials have been recently studied due to their wide applications in optoelectronics, industry, product inspection, and spectroscopy. Terahertz frequency applications are promising for the medical field as they are considered safe frequencies. Previous terahertz plasma response focused on 2D materials like graphene and transition metal dichalcogenides (TMDs) due to their favourable electronic properties, high electric conductivity, and their band gap characteristics, so they can be used in electronic devices. Some of these materials showed good biocompatibility so they can be used in biomedical applications. Since graphene has zero band gap, researchers are continuously exploring methods to increase its band gap to be used in electronics. Graphene heterostructures or metamaterials are ways to enhance graphene characteristics for specific applications. This work investigates the possibility of using MoS2 with graphene in THz applications. The plasmon dispersion for graphene and MoS2 nanoribbon array structure is compared. Both graphene and MoS2 behave differently in response to terahertz radiation due to their different band gaps. The results showed that MoS2 exhibits a plasmonic response in the THz region at high carrier concentrations. This opens up opportunities for MoS2 to be employed in THz sensors, both independently and in conjunction with graphene within heterostructures or metamaterials for power sources and detectors. These advancements hold significant potential for the future THz imaging and communication technologies.
Upper Subcell Impacts on Perovskite/u-CIGS Tandem Solar Cell Performance
Authors: Boukortt Nour , Abdulraheem Yaser M. , Patanè Salvatore , Lenka Trupti Ranjan , Paul Rabin , AlAmri Amal M. , Wafi Malak , Mohammad Mariam Ali , Almuraished Anfal , Alenezi Noor , Alameeri Latifa , Alenezi Zainab , Nasri Wissem , Hadri Baghdad
Published: May 2024

In this paper, the two-terminal perovskite/u-CIGS tandem cells have been numerically performed and studied by using TCAD tools. The investigated planar perovskite model has been performed accordingly in order to match the fabricated structure and to be used as a top cell for tandem cells. The ultrathin CIGS solar cell has been also calibrated according to the fabricated model in order to be used as a good substrate (bottom cell) for the top cell (perovskite). These two cells have been simulated individually and they have revealed an efficiency of up to 20 % and 12.51 % for perovskite and u-CIGS models, respectively. The 2-terminal tandem model is then developed by comprising the top cell with the bottom cell by transparent contact that connects the two sub-cells in series electrically. The influence of changing the defect density in the perovskite film (absorber) and at ETL/absorber and absorber/HTL interfaces on tandem cell characteristics are analyzed. Moreover, we show that the power conversion efficiency of this investigated tandem model can reach over 30% by reducing defect densities and adjusting some sub-cell parameters that were already optimized in our previously published work. These approaches allow us to gain a better understanding of the physical dimensions and defect densities’ effect on the performance of the tandem devices.
The Effect of Antioxidants on the Stability of Perovskite Solar Cells
Authors: Alzubaidi Fatima , Zhang Di , Tabet Nouar
Published: May 2024

The passivation of defects present in the bulk and surface of the perovskite absorbing layers of solar cells is currently the subject of intense research. To address this issue, dopants can be used to minimize the density of defects that occur at the surface and grain boundaries of perovskite films. Herein, we introduced two new antioxidants (Morin and Quercetin) in the precursor solutions to passivate the defects present in the Cs0.1FA00.9PbI3 perovskite absorbing layer. The positive impact of antioxidants on the efficiency of perovskite cells has been recently reported. However, more experimental data are needed to identify the most effective passivating agent. The time resolved photoluminescence measurements revealed that the added molecules increased the photocarrier lifetime by 120-194%. Our results showed that the optimum concentrations are 2.223 mM for Morin and 0.0156 mM for Quercetin. These results demonstrate that the new molecules are effective passivating agents and have the potential to improve the device performance. The variation of the cell power conversion efficiency as function of the concentration of the antioxidants will be discussed.
Flexural response of sandwich structures comprising topologically perturbed cores
Authors: Osman Omar Al , Alkhader Maen , Abuzaid Wael
Published: May 2024

Enhancing the flexural stiffness of sandwich structures comprising honeycomb cores through perturbing their cellular cores is explored computationally in this work. In-plane sinusoidal perturbations are imposed on the ligaments of hexagonal cores to increase their second moment of inertia and flexural load-carrying capacity. The sensitivity of sandwich structures’ flexural strength, peak load and specific energy absorption to the imposed perturbation is investigated. Introduced perturbations are controlled through their amplitude and frequency. Results show that increasing the perturbation frequency and amplitude generally increases the flexural stiffness and peak loads of sandwich structures with perturbed cores without compromising their lightweight properties. However, low frequencies and amplitudes had a negligible effect on the sandwich structures’ mechanical properties.
LIPSS formation on Ni surface using mixed near-infrared laser beam harmonics
Authors: Khalil Baha , Alnaser Ali S
Published: May 2024

Generation of laser-induced periodic surface structures (LIPSS) is investigated with femtosecond laser pulses with 1030nm wavelength and its second and its harmonics. The second (λ2ω
= 515nm) and third harmonics (λ3ω
= 343nm) beams in addition to their combination were utilized to control the period of the LIPSS on a Ni surface. The resulting periodicity of the formed structures was ∼ 0.42μm, 0.22μm, and 0.33μm respectively for the second harmonic beam, third harmonic beam, and their combination. This method demonstrates a direct way to control the periodicities on a metal target by employing an individual laser beam wavelength to induce a variable range of LIPSS periods.
Chips for calibration of the ATLAS Liquid Argon calorimeter
Authors: Raux L. ,   the ATLAS Liquid Argon calorimeter calibration group
Published: May 2024

The LHC upgrade requires redoing the liquid Argon (LAr) calibration system which should provide a 16-bit range signal with 1‰ accuracy while being radiation tolerant. The fundamental operating principle remains unchanged: a precise current is stored in an inductor, and upon switching off the current, a pulse is generated for injection into the readout electronics. This is achieved by two chips: the first one, in CMOS 130 nm, provides the 16-bit DAC as well as the calibration management system; the second one, in XFAB 180 nm, embeds switches to generate the pulses. A description of both chips and measurement results will be presented.
Dynamical chaos and level splitting under the channeling of the high energy positrons in [100] direction of the silicon crystal
Authors: Syshchenko V.V. , Tarnovsky A.I. , Dronik V.I. , Isupov A.Yu.
Published: May 2024

The motion of charged particles in a crystal in the axial channeling regime can be both regular and chaotic. The chaos in quantum case manifests itself in the statistical properties of the energy levels set. These properties have been studied previously for the electrons channeling along [110] direction of the silicon crystal, in the case when the classical motion was completely chaotic, as well as for the ones channeling along [100] direction, when the classical motion can be both regular and chaotic for the same energy depending on the initial conditions. Here we study the positrons channeling in [100] direction. This case is of special interest due to the substantial tunneling probability between dynamically isolated regular motion domains in the phase space. The interaction of the energy levels via tunneling distinctly changes the level spacing statistics. All transverse motion energy levels as well as corresponding stationary wave functions are computed numerically for the 30 GeV positrons channeling in [100] direction of the silicon crystal. The values of the matrix elements for the tunnel transitions are
extracted
from these data. These results confirm the chaos assistance for the tunneling and the level splitting. These values will be used in the further researches of the quantum chaos manifestations in the channeling phenomenon.