bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrocaloric effect in pure and NaNbO3-modified Na0.5Bi0.5TiO3–BaTiO3 solid solutions near the morphotropic phase boundary
Authors: Eberlins Ojars Martins , Dunce Marija , Kundzins Maris , Birks Eriks
Published: September 2023

Morphotropic phase boundary of ferroelectric solid solutions attracts interest with respect to not only improved piezoelectric properties but also the electrocaloric effect, which is attractive to build new-generation cooling devices. In the present study, the electrocaloric effect in (1 − x − y)Na0.5Bi0.5TiO3–xBaTiO3–yNaNbO3 near its morphotropic phase boundary is studied by direct measurements of temperature change ΔT. ΔT maximum is observed in the region of depolarization temperature, where the major contribution comes from an entropy jump at the electric field-induced phase transition. Differences between ΔT values measured when an electric field pulse is applied and removed are explained by slow domain rearrangement in the ferroelectric phase and metastability of phases close to the depolarization temperature. Among studied compositions, the highest value of ΔT is obtained for the compositions 0.94Na0.5Bi0.5TiO3–0.06BaTiO3 and 0.93Na0.5Bi0.5TiO3–0.06BaTiO3–0.01NaNbO3 in the region of depolarization temperature. Examples of the comparison of the directly measured values of ΔT and the values calculated using the Maxwell relation revealing inconsistency between the two methods in the ferroelectric and the nonferroelectric phase are presented.
Static magnetic signature of a ghost-ship propulsor system as a composite ferromagnetic medium
Authors: Zivieri R. , Palomba G. , Consolo G. , Proverbio E.
Published: September 2023

In this paper, it is shown that the static magnetic signature of a propulsor belonging to a ghost ship, whose hull is made of fiberglass, can be calculated by regarding it as a composite ferromagnetic medium. The calculation of the magnetic signature in the static regime is carried out using finite-element method simulations and according to a simple analytical model based on the concepts of volume averaged magnetization arising from a source magnetic field, volume averaged permeability, surface magnetic charges, and the demagnetization tensor applied to a composite magnetic medium. Using targeted simulations, it is demonstrated that the magnetostatic field of demagnetizing nature forming inside the propulsor almost cancels the contribution of the volume averaged magnetization. From the interplay between the numerical simulations and the analytical model, the elements of the demagnetization tensor in the region filled by the propulsor are locally calculated, and their role in determining the localization effects of the magnetic signature is discussed. By replacing the original ferromagnetic materials with weakly ferromagnetic ones, it is shown that, in the underwater region outside the propulsor, the magnetic signature drop is 64%. This analysis suggests an experimental way to use a simple passive method to minimize the magnetic signature of a propulsor as an alternative to more complex and time-consuming methods, such as the deperming and degaussing methods, widely employed to reduce the magnetic signature of ships and underwater objects in military applications.
Development of SQUID detection technology for a superconducting gravimeter
Authors: Kim Gracia , Choi In-Mook
Published: September 2023

In this paper, we present research on the development of SQUID (Superconducting QUantum Interference Device) detection technology for a superconducting gravimeter (SG), aiming to achieve precise real-time measurements of gravity. We provide an introduction to the composition and internal details of the SQUID-based superconducting gravimeter (SSG). The internal components of the SSG are designed based on theoretical calculations to optimize the system and enhance its sensitivity. With the current in the levitation coil set to persistent mode, a unique proof mass is levitated through electromagnetic force. We demonstrate the equilibrium position of the levitated proof mass by assessing the change in the coil inductance. Furthermore, we present preliminary experimental results of earth tidal measurements using the developed SQUID detection technology and compare these outcomes with measurements from an absolute gravimeter (FG5X) and with theoretical calculations. These comparisons confirm the potential of the proposed new gravity measurement technology.
A novel uncertainty evaluation method based on the particle filter and beta distribution for data with unknown distribution
Authors: Cheng Zhenying , Chen Xu , Liu Liying , Cheng Dongxu , Huang Qiangxian , Li Ruijun
Published: September 2023

Uncertainty evaluation for unknown distribution data is a key problem to be solved in uncertainty evaluation theory. To evaluate the measurement uncertainty of data with unknown distributions, a novel uncertainty evaluation method based on the particle filter (PF) and beta distribution is proposed in this paper. A beta distribution with wide adaptability was adopted as the distribution type of measurement results, the parameters of the beta distribution were taken as the parameters to be estimated, and a state-space model was established. The PF method, suitable for non-Gaussian data, was utilized to obtain the estimates of the parameters of the beta distribution according to the measurement results. Finally, the best estimates of the measurement results and their uncertainty were calculated using the beta distribution parameters. Simulation results show that the proposed method is adaptive to accurately evaluate the measurement uncertainties of data, especially for non-Gaussian distribution data or asymmetrically distributed data. Multiple evaluation results show that the method has good robustness. The experimental results for the drift errors of a laser interferometer show that the uncertainty result of the proposed method is consistent with the Monte Carlo method. This method is suitable for a variety of distribution types that can be characterized through beta distribution and can solve the optimal estimation and uncertainty evaluation of most measurement results with unknown distribution types.
An analytic and complete equation of state for condensed phase materials
Authors: Lozano Eduardo , Cawkwell Marc J. , Aslam Tariq D.
Published: September 2023

Analytic equations of state (EOS) are intended to reproduce theoretical and experimental data in a single phase portion of the thermodynamic space. We devise a complete and thermodynamically consistent model with four distinct features: (1) a reference isotherm that remains thermodynamically stable, (2) a flexible specific heat model based on a fourth-order rational polynomial, (3) a Grüneisen parameter that depends on specific volume and temperature, and (4) pressure and internal energy functions that can be inverted analytically in temperature. The model aims to improve the accuracy of existing equations of state while remaining computationally efficient. To demonstrate its features, we include calibrations for single-crystal pentaerythritol tetranitrate (PETN), liquid nitromethane (NM), and hexagonal close-packed beryllium (Be) metal. The parameter optimization uses the specific heat capacity, Grüneisen parameter, and static compression curves obtained from density functional theory for the crystalline solids and molecular dynamics simulations for liquid NM. We also present a velocity autocorrelation function that yields accurate phonon densities of states for the EOS calibration from the molecular dynamics trajectories. Each of the three calibrations is constrained to enforce the ambient state from experimental measurements and validated against experimental Hugoniot data from multiple sources. We also include one-dimensional hydrodynamic simulations of the isentropic compression experiments for beryllium conducted at the Z facility.
Toward radiative-limited coherence of erbium dopants in a nanophotonic resonator
Authors: Yang Likai , Wang Sihao , Tang Hong X.
Published: September 2023

Atomic-like emitters in the solid state serve as important resources in the advancement of future quantum networks. In particular, intra-4f optical transitions of rare earth ions exhibit excellent coherence properties thanks to the shielding effect of outer electrons. Still, the presence of various dephasing channels in solid state hosts introduces additional decoherence beyond the radiative decay, causing the coherence time of most rare earth doped materials to be over an order of magnitude lower than the radiative limit. Such obstacle prevents the emission of indistinguishable photons from rare earth ions, which is an essential requirement for various quantum applications. In this work, we perform optical coherence study on erbium ions doped in thin-film lithium niobate by patterning photonic crystal resonators with quality factor around 100 k and sub-λ3 mode volume. Leveraging the combination of long coherence and strong Purcell enhancement in the cavity, we show that the coherence time measured with photon echo approaches the radiative limit (80%), representing a 50-fold improvement compared to the waveguide case. Our results present promising prospects toward utilizing rare earth doped materials as quantum repeaters and sources of indistinguishable photons.
Influence of electrostriction and voltage-induced screening effects on the tunnel electroresistance in tunnel junctions with composite ferroelectric barriers
Authors: Jagga Deepali , Useinov Artur
Published: September 2023

The electron transport characteristics of magnetic and non-magnetic ferroelectric tunnel junctions based on Hf0.5Zr0.5O2 are investigated in this study. A modified linear approach to the Thomas–Fermi interfacial screening model is employed to simulate these properties. This method is developed by leveraging the quantum approximation of the quasiclassical spin-resolved point-like contact formalism. The oxygen vacancies, voltage-induced screening, and electrostriction effect are the key phenomena exploited to build the potential profile and hence to simulate the resistive switching characteristics of the ferroelectric tunnel junctions. To validate its precision, the model is extensively verified with experimental data. The obtained model is generalized to reproduce mono-domain and multi-domain ferroelectric switching, featuring its effectiveness for non-volatile storage devices and ferroelectric-field effect transistors.
von Kármán vortex streets around invisible bluff bodies
Authors: Vadasz Peter
Published: September 2023

Satellite images captured during the past decade identify clearly von Kármán vortex streets in the atmosphere above certain islands in the Atlantic and Pacific Oceans. The vortex streets are visible due to the cloud formations since the latter behave as unintended tracers of the fluid motion driven by winds. Experimental as well as numerical simulation results of von Kármán vortex shedding for flow around a cylinder or other bluff body identify the latter in a certain range of Reynolds numbers. The satellite images, however, show these von Kármán vortex structures at elevations well above the ground level inviting the appealing question of where is the cylinder or the bluff body? This short paper identifies the answer to this question as the creation of Taylor–Proudman columns above the islands that are invisible until a tracer makes them detectable at a certain height above the island. The latter also provides the clarification that the flow is geostrophic at the leading order and consequently two-dimensional (i.e., variations occur in the horizontal directions with no leading order changes in the vertical direction). In addition, this paper shows that a small Rossby number is not a necessary requirement for the creation of Taylor–Proudman columns. The latter can emerge also if a certain modified Beltrami condition is satisfied even when Rossby number is not small.
Experimental study on the influence of cracked kerosene gas temperature on the propagation characteristics of rotating detonation waves
Authors: Han Jiaxiang , Bai Qiaodong , Qiu Han , Liu Zhuyong , Weng Chunsheng
Published: September 2023

The product of kerosene pre-combustion pyrolysis is typically used as the fuel for rotating detonation, and pure air at an ambient temperature is used as the oxidizer. The temperature of cracked kerosene gas (CKG) is determined by changing the supply conditions of the pre-combustion chamber. Therefore, the influence of the CKG temperature on the detonation range and rotating detonation wave (RDW) propagation was determined in this study. The experimental results show that the initiation delay time decreases with increasing CKG temperature. The temperature of CKG increased from 633 to 980 K, and two modes of RDW propagation appeared: the single rotating detonation wave (SRDW) and intermittent single rotating detonation wave (ISRDW) modes. In the temperature range of each propagation mode, the RDW velocity increased with the CKG temperature. Moreover, the average pressure of RDW propagation decreased with increasing CKG temperature. The stability of RDW propagation was reduced mainly because the propagation mode was changed to ISRDW. Thus, increasing the CKG temperature widens the range of CKG and air initiation. Moreover, the equivalent ratio interval of RDW propagation in the SRDW mode increases from low to high with an increase in the CKG temperature.
Properties of water and argon clusters developed in supersonic expansions
Authors: Klíma Martin , Celný David , Janek Jiří , Kolafa Jiří
Published: September 2023

Using adiabatic molecular dynamics coupled with the fluid dynamics equations, we model nucleation in an expanding beam of water vapor and argon on a microsecond scale. The size distribution of clusters, their temperature, and pickup cross sections in dependence on velocity are investigated and compared to the geometric cross sections and the experiment. The clusters are warmer than the expanding gas because of the time scale of relaxation processes. We also suggest that their translational and rotational kinetic energies are modified due to evaporative cooling. The pickup cross sections determined for the final clusters using molecules of the same kind increase with decreasing velocity, still obeying the (a+bN1/3)2 law.
A vacuum-compatible cylindrical inertial rotation sensor with picoradian sensitivity
Authors: Ross M. P. , van Dongen J. , Huang Y. , Zhou H. , Chowdhury Y. , Apple S. K. , Mow-Lowry C. M. , Mitchell A. L. , Holland N. A. , Lantz B. , Bonilla E. , Engl A. , Pele A. , Griffith D. , Sanchez E. , Shaw E. A. , Gettings C. , Gundlach J.
Published: September 2023

We describe an inertial rotation sensor with a 30-cm cylindrical proof-mass suspended from a pair of 14 μm thick BeCu flexures. The angle between the proof-mass and support structure is measured with a pair of homodyne interferometers, which achieve a noise level of ∼5prad/Hz. The sensor is entirely made of vacuum compatible materials, and the center of mass can be adjusted remotely.
Dynamics of rigid achiral magnetic microswimmers in shear-thinning fluids
Authors: Quashie David , Wang Qi , Jermyn Sophie , Katuri Jaideep , Ali Jamel
Published: September 2023

Here, we use magnetically driven self-assembled achiral swimmers made of two to four superparamagnetic micro-particles to provide insight into how swimming kinematics develop in complex, shear-thinning fluids. Two model shear-thinning polymer fluids are explored, where measurements of swimming dynamics reveal contrasting propulsion kinematics in shear-thinning fluids vs a Newtonian fluid. When comparing the velocity of achiral swimmers in polymer fluids to their dynamics in water, we observe kinematics dependent on (1) no shear-thinning, (2) shear-thinning with negligible elasticity, and (3) shear-thinning with elasticity. At the step-out frequency, the fluidic environment's viscoelastic properties allow swimmers to propel faster than their Newtonian swimming speed, although their swimming gait remains similar. Micro-particle image velocimetry is also implemented to provide insight into how shear-thinning viscosity fluids with elasticity can modify the flow fields of the self-assembled magnetic swimmers. Our findings reveal that flow asymmetry can be created for symmetric swimmers through either the confinement effect or the Weissenberg effect. For pseudo-chiral swimmers in shear-thinning fluids, only three bead swimmers show swimming enhancement, while four bead swimmers always have a decreased step-out frequency velocity compared to their dynamics in water.
Numerical simulation of the horizontal rotating cylinder and the air entrainment near the free surface
Authors: Guo Chunyu , Ji Minglei , Han Yang , Liu Tian , Wu Yanyuan , Kuai Yunfei
Published: September 2023

The flow around a cylinder near a free surface contains many physical phenomena and mechanisms, especially when the cylinder is moving. In this paper, the two-dimensional flow of a rotating cylinder near the free surface is simulated. The dynamic behavior of the rotating cylinder and the flow characteristics such as force coefficient, vortex structure, and air entrainment under different depth ratios, Fr numbers, and rotation ratios are discussed. In such problems, the rotational motion is rarely mentioned. The two-phase model is the sharp volume of the fluid method based on the two-dimensional incompressible Navier–Stokes equation. Combined with the spatially adaptive four-octree grid, the gas–liquid interface is reconstructed with the high-density ratio (ρwater/ρair = 816). The results show that, at α ≤ 2.0, the combined effect of the free surface and the rotation causes the wake vortex to produce a positive upper and negative lower distribution, which is contrary to the single condition. For the rotating cylinder, the existence of a free surface leads to the stable vortex layer at a low rotation ratio (α = 1.0), which only occurs at the high rotation ratio (2 < α < 4.2) without free surface. For the force coefficients, the simultaneous existence of the free surface and the rotation obviously changes the value and periodicity of the coefficients, which is different from the single condition. As for the air entrainment, it can be divided into two categories within the selected parameters: vortex entrainment caused by the parallel free surface and wake jet entrainment. In the latter model, the entailed bubbles have a wider distribution in space due to the influence of shedding vortices.
Violet phosphorus nanosheets for room-temperature dimethylamine detection and mechanism insights by DFT calculation
Authors: Hu Yinhua , Chang Xiao , Zhang Jun , Liu Xianghong
Published: September 2023

Two-dimensional (2D) materials offer great prospects in room temperature (RT) gas sensors with minimum power consumption, compared to conventional metal oxide semiconductor sensors that require high temperature operation. In this work, we prepared violet phosphorus (VP) nanosheets by optimized liquid-phase exfoliation in various solvents. A highly sensitive gas sensor has been fabricated by using the prepared VP nanosheets for detection of dimethylamine (DMA), a toxic chemical widely used in various industries. The VP sensor shows an ultrafast response time of ∼2 s and high response to DMA at RT. The sensing mechanism has been analyzed by density functional theory calculations, revealing significant electron transfer from DMA to VP. This work explores the promise of VP in low power sensors.
High-efficiency phase-locking experiment of modular Ka-band coaxial magnetrons
Authors: Song Minsheng , Meng Lin , Li Shengen , Wu Zhaohui , Bi Liangjie , Qin Yu , Liu Haixia , Chen Liangping , Wang Bin , Yin Yong , Li Hailong
Published: September 2023

The first full demonstration of a high-efficiency phase-locking mechanism was accomplished in the millimeter-wave (mm wave) bands. Two modular Ka-band coaxial magnetrons were fabricated and phase-locked. The coaxial magnetron consisted of a conventional structure and a carefully designed coupling port that included an RF window. The coupling ports of two magnetrons were connected by coupling bridges to phase lock the coaxial magnetrons in zero-phase and π-phase difference mode, reaching phase-locking efficiencies of 93.4% and 95.6%, respectively. Two phase-locking modes were both verified by a mode detection system based on a symmetrical E-plane T-junction and a high bandwidth, high sample rate oscilloscope. Signals from the oscilloscope confirmed that phase-locking occurred after 25 ns and was reproducible from pulse to pulse. With higher power and more coaxial magnetrons in arrays, 1 MW may be achievable at Ka-band.
Bipolar ferromagnetic semiconductors and dipole-modulated magnetism in two-dimensional Janus transition metal dihalides
Authors: Chen Ze-Yan , Wang Yue-Yi , Hou Ting-Ping , Liu Nan-Shu , Lin Heng-Fu
Published: September 2023

Two-dimensional (2D) transition metal dihalides (TMDHs) have attracted great interest owing to their unique magnetic and semiconductor properties. Compared with the mirror/inversion symmetric materials, 2D Janus materials possess vertical intrinsic dipole moment, which offer a versatile platform for the fundamental physics and future spintronic devices. Here, we systematically explore the magnetic and electronic properties of the 2D Janus transition metal dihalides MXY (M = Co and Ni; X ≠ Y = Cl, Br, and I) monolayers and bilayers by using density functional theory. The monolayer CoClBr, NiClBr, and NiBrI are bipolar ferromagnetic semiconductors that possess the valence and conduction band edges of different spin channels. The magnetism of the bilayer CoClBr, NiClBr, and NiBrI is highly dependent on the accumulated dipole moments of the two adjacent layers. When the dipole moments in both layers are aligned in the same direction and the accumulated dipole moments are nonzero, the systems are antiferromagnetic half semiconductors. However, when the dipole moments in the two layers are opposite and the accumulated dipole moments are zero, the systems are A-type antiferromagnetic semiconductors. Our findings are helpful to understand the magnetism of Janus TMDHs and guide experiments in exploring their potential application in spintronic devices.
Kinetic isotope effect study of N-6 methyladenosine chemical demethylation in bicarbonate-activated peroxide system
Authors: Li Fangya , Wang Ying , Zhang Jianyu
Published: September 2023

N-6 methyladenosine is the most abundant nucleic acid modification in eukaryotes and plays a crucial role in gene regulation. The AlkB family of alpha-ketoglutarate-dependent dioxygenases is responsible for nucleic acid demethylation. Recent studies have discovered that a chemical demethylation system using hydrogen peroxide and ammonium bicarbonate can effectively demethylate nucleic acids. The addition of ferrous ammonium sulfate boosts the oxidation rate by forming a Fenton reagent with hydrogen peroxide. However, the specific mechanism and key steps of this process remain unclear. In this study, we investigate the influence of ferrous ammonium sulfate concentration on the kinetic isotope effect (KIE) of the chemical demethylation system using LC-MS. As the concentration of ferrous ions increases, the observed KIE decreases from 1.377 ± 0.020 to 1.120 ± 0.016, indicating a combination of the primary isotope effect and inverse α-secondary isotope effect with the ion pairing effect. We propose that the initial hydrogen extraction is the rate-limiting step and observe a tight transition state structure in the formation of the hm6A process through the analysis of KIE trends. The concentration-dependent KIE provides a novel perspective on the mechanism of chemical demethylation and offers a chemical model for enzyme-catalyzed demethylation.
Dynamical behavior of viscoelastic functionally graded tapered rotors partially filled with liquid
Authors: Jiang Zhongkai , Wang Guangding , Zhao Qing , Yuan Huiqun
Published: September 2023

In this study, the dynamics and stability of a viscoelastic functionally graded tapered rotor partially filled with liquid are investigated. It is assumed that the radius of the rotor varies linearly, while the density and elastic modulus change exponentially along the longitudinal direction of the rotor. The Kelvin–Voigt model is utilized to describe the viscoelastic material. The governing equations of motion of the rotor system are established via Hamilton's principle. By using the Laplace transform and the Galerkin method, the characteristic equation of the system is obtained. Then, the complex frequencies of the system are computed in the first order on the basis of the characteristic equation. The critical divergence and flutter rotating speeds are acquired. The stability of the rotor system with viscoelastic effects is examined. Finally, the effects of the main parameters including the gradient parameter, taper ratio, hollowness ratio, mass ratio, cavity ratio, and the viscoelastic coefficient on the dynamical behavior of the system are discussed, respectively. The results show that the stability of the system is strongly dependent on these parameters. Also, the results indicate that the viscoelasticity of the material mainly affects the stability evolution of the rotor system.
Measuring prion propagation in single bacteria elucidates a mechanism of loss
Authors: Jager Krista , Orozco-Hidalgo Maria Teresa , Springstein Benjamin Lennart , Joly-Smith Euan , Papazotos Fotini , McDonough EmilyKate , Fleming Eleanor , McCallum Giselle , Yuan Andy H. , Hilfinger Andreas , Hochschild Ann , Potvin-Trottier Laurent
Published: September 2023

Prions are self-propagating protein aggregates formed by specific proteins that can adopt alternative folds. Prions were discovered as the cause of the fatal transmissible spongiform encephalopathies in mammals, but prions can also constitute nontoxic protein-based elements of inheritance in fungi and other species. Prion propagation has recently been shown to occur in bacteria for more than a hundred cell divisions, yet a fraction of cells in these lineages lost the prion through an unknown mechanism. Here, we investigate prion propagation in single bacterial cells as they divide using microfluidics and fluorescence microscopy. We show that the propagation occurs in two distinct modes. In a fraction of the population, cells had multiple small visible aggregates and lost the prion through random partitioning of aggregates to one of the two daughter cells at division. In the other subpopulation, cells had a stable large aggregate localized to the pole; upon division the mother cell retained this polar aggregate and a daughter cell was generated that contained small aggregates. Extending our findings to prion domains from two orthologous proteins, we observe similar propagation and loss properties. Our findings also provide support for the suggestion that bacterial prions can form more than one self-propagating state. We implement a stochastic version of the molecular model of prion propagation from yeast and mammals that recapitulates all the observed single-cell properties. This model highlights challenges for prion propagation that are unique to prokaryotes and illustrates the conservation of fundamental characteristics of prion propagation.
Internal feedback in the cortical perception–action loop enables fast and accurate behavior
Authors: Li Jing Shuang , Sarma Anish A. , Sejnowski Terrence J. , Doyle John C.
Published: September 2023

Animals move smoothly and reliably in unpredictable environments. Models of sensorimotor control, drawing on control theory, have assumed that sensory information from the environment leads to actions, which then act back on the environment, creating a single, unidirectional perception–action loop. However, the sensorimotor loop contains internal delays in sensory and motor pathways, which can lead to unstable control. We show here that these delays can be compensated by internal feedback signals that flow backward, from motor toward sensory areas. This internal feedback is ubiquitous in neural sensorimotor systems, and we show how internal feedback compensates internal delays. This is accomplished by filtering out self-generated and other predictable changes so that unpredicted, actionable information can be rapidly transmitted toward action by the fastest components, effectively compressing the sensory input to more efficiently use feedforward pathways: Tracts of fast, giant neurons necessarily convey less accurate signals than tracts with many smaller neurons, but they are crucial for fast and accurate behavior. We use a mathematically tractable control model to show that internal feedback has an indispensable role in achieving state estimation, localization of function (how different parts of the cortex control different parts of the body), and attention, all of which are crucial for effective sensorimotor control. This control model can explain anatomical, physiological, and behavioral observations, including motor signals in the visual cortex, heterogeneous kinetics of sensory receptors, and the presence of giant cells in the cortex of humans as well as internal feedback patterns and unexplained heterogeneity in neural systems.
Wear behaviour of alumina-toughened-zirconia composites with different phase arrangement under ball-on-flat tribological tests
Authors: Grabowy Marek , Wojteczko Agnieszka , Osada Piotr , Wiązania Grzegorz , Pędzich Zbigniew
Published: September 2023

An alumina-toughened zirconia (ATZ) material, fabricated using a procedure consisting of the common sintering of two different zirconia powders, was tested using the ball-on-disc method in a temperature range between room temperature and 400°C. Tetragonal zirconia balls were used as a counterpart. Two different types of microstructure were designed, one consisting of separated alumina inclusions in a zirconia matrix and another one which was a combination of two continuous phases, penetrating the whole volume of the composite. It was detected that at elevated temperatures both materials showed a distinct decrease in the wear rate. Composite with a low alumina content showed minimal wear rate at 300°C and composite with higher amount of alumina showed it at 400°C. There are some observations that this minimal wear rate result is connected with a pseudoplastic behaviour of a layer formed between co-operating elements of tribological pair. This layer is composed of the debris of both, sample and counterpart, and its behaviour during sliding is connected with the mean grain size of this debris which is correlated with the mean grain size of sintered material.
Plasmonic titanium nitride nanomaterials prepared by physical vapor deposition methods
Authors: Mascaretti Luca , Mancarella Cristina , Afshar Morteza , Kment Štěpán , Bassi Andrea Li , Naldoni Alberto
Published: September 2023

Titanium nitride (TiN) has recently emerged as an alternative to coinage metals to enable the development of integrated plasmonic devices at visible and medium-infrared wavelengths. In this regard, its optical performance can be conveniently tuned by tailoring the process parameters of physical vapor deposition methods, such as magnetron sputtering and pulsed laser deposition (PLD). This review first introduces the fundamental features of TiN and a description on its optical properties, including insights on the main experimental techniques to measure them. Afterwards, magnetron sputtering and PLD are selected as fabrication techniques for TiN nanomaterials. The fundamental mechanistic aspects of both techniques are discussed in parallel with selected case studies from the recent literature, which elucidate the critical advantages of such techniques to engineer the nanostructure and the plasmonic performance of TiN.
Plasma sputtering of biased electrodes in an oblique magnetic field
Authors: Hiret Paul , Soni Kunal , Cherukulappurath Mana Anil , Faudot Eric , Moser Lucas , Steiner Roland , Geraldini Alessandro , Alberti Stefano , Furno Ivo , Moritz Jérôme , Brochard Frédéric , Heuraux Stéphane , Marot Laurent , Meyer Ernst
Published: September 2023

The surface erosion of biased electrodes immersed in a radio frequency (RF) plasma was investigated in oblique magnetic fields ranging from 0.1 T to 3.5 T. The plasma potential and density in the vicinity of the biased electrode have been measured using an RF-compensated cylindrical Langmuir probe moved by a three-dimensional motorised arm in the ALINE facility at 0.1 T. The erosion profiles were determined for different gases (argon and helium), magnetic field strength and plasma volume for the same electrode surface area at an angle of 5∘ with the magnetic field in three different experimental geometries. The radial electric field (perpendicular to the magnetic field) in the plasma column has been deduced from plasma potential measurements. This radial field makes the ions converge to the core of the plasma column at grazing angles (

<

30∘) and is reversed at larger angles. The ion flux on the sample increases with the magnetic field magnitude leading to a strong erosion inhomogeneity. At lower plasma volume, the erosion rate is sensitively enhanced. Local redeposition was identified using x-ray photoelectron spectroscopy on the surfaces exhibiting preferential deposition directions. Finally, the asymmetric erosion patterns obtained from a molybdenum layer etching are explained by the similar asymmetric density maps obtained with the probe and by the

E
→

×

B
→

drift and the local sheath acceleration.
Impact of bimetal doping on the structural and optical characteristics of copper oxide nanoparticles to enhance photocatalytic degradation of dyes: an investigative study
Authors: Abhilasha  , Kumari Neeraj , Gautam Rajni
Published: September 2023

Metal oxide nanoparticles have attracted a lot of attention for dye degradation applications as they have better light absorption properties required for the photocatalysis. This paper presents the impact of bi-metal doping (i.e. Cerium and Tungsten) on the structural and optical properties of Copper oxide nanoparticles. Bi-metal doping has shown remarkable impact on the optical properties (i.e. enhanced light absorption) of CuO nanoparticles making it suitable for photocatalytic applications. A simple co-precipitation method was used to synthesize the pure, single-metal doped and bi-metal doped (i.e. Ce, W and Ce-W) CuO nanoparticles. XRD analysis was done to study the structural properties along with crystallite size estimation using Debye-Scherer formula. Absorption band at 852 cm−1 and 650 cm−1 in the FT-IR spectra further confirmed the presence of CeO2 & WO2 in the monoclinic phase of CuO nanoparticles. Maximum absorption wavelength and bandgap are measured using UV–vis Spectroscopy, and it has been observed that both these quantities depend upon the choice of dopant and can be tailored just by choosing the appropriate dopant. The paper presents an extensive analysis using experimental study to compare the impact of Ce, W and bimetal (Ce-W) doping on the structural, optical and photocatalytic properties of CuO nanoparticles. Enhanced optical absorption in the complete visible range is observed in case of bi-metal doped CuO nanoparticles making it a promising candidate for photocatalytic dye degradation application.
Effect of varying functional monomers in experimental self-adhesive composites: polymerization kinetics, cell metabolism influence and sealing ability
Authors: Ferreira Marta Nunes , Neves Dos Santos Marta , Fernandes Inês , Marto Carlos Miguel , Laranjo Mafalda , Silva Diana , Serro Ana Paula , Carrilho Eunice , Botelho Maria Filomena , Azul Ana Mano , Delgado António HS
Published: September 2023

The aim was to evaluate the effects of adding different functional monomers to experimental self-adhesive composites (SACs) on polymerization kinetics, cell metabolic activity, and sealing ability. SACs were formulated using urethane dimethacrylate as the base monomer and triethylene glycol dimethacrylate. Additionally, 10 wt.% of distinct functional monomers were added - 10-methacryloyloxydecyl dihydrogen phosphate, glycerol phosphate dimethacrylate (GPDM), 2-hydroxyethyl methacrylate (HEMA) or hydroxyethyl acrylamide (HEAA). ATR-FTIR was used to determine real-time polymerization kinetics (20 min, n = 3). The final extrapolated conversion and polymerization rates were determined (DC

,max;
Rp

,max). The DC

,max values were employed to calculate volumetric shrinkage. The MTT assay was performed on MDPC-23 cells using disc extracts at different concentrations (n = 8). Class V cavities were prepared in 60 sound human molars, assigned to six groups (n = 10), depending on the composite used and aging type (T0 or TC, if thermocycled for 10 000 cycles). One-way ANOVA, two-way, and Kruskal–Wallis tests were employed to treat the data (ɑ = 0.05). Varying the functional monomers had a large impact on DC,max, as confirmed by one-way ANOVA (p<0.001). The highest was obtained for HEMA (64 ± 3%). The HEMA and HEAA formulations were found to be significantly more toxic at concentrations below 100%. For microleakage, having a functional monomer or not did not show any improvement, irrespective of margin or aging period (Mann–Whitney U, p > 0.05). Larger functional monomers MDP and GPDM affected polymerization properties. Conversely, their acidity did not seem to be detrimental to cell metabolic activity. Regarding sealing ability, it seems that the functional monomers did not bring an advantage to the composites. Varying the functional monomer in SACs had a clear impact on the polymerization kinetics as well as on their cytotoxic potential. However, it did not confer better microleakage and sealing. Claiming self-adhesiveness based only on functional monomers seems dubious.
The Correlation of Land Survey and Satellite Gravity Data. Study Case: Timor Leste Area
Authors: Toifur Ahmad , Kunadi Ziyad Fakhri , Alawiyah Susanti , Gunawan Indra
Published: September 2023

The gravity method has been widely used in tectonic studies and the determination of geological structures. Besides land surveys, gravity data can also be measured by using satellites. However, the gravity data obtained from the satellite is usually not as good as the land survey. For example, the satellite data provided by Topex has a resolution of 1-minute grids, while the land survey could have a higher resolution. It means the gravity data obtained from the satellite cannot be as detailed as the land survey. To understand the relationship between both data, we calculate the correlation on the CBA, regional, and residual map. We also compared the maps qualitatively with geological data. During our investigation in the Timor Leste area, it was found that the correlation value between the CBA, regional, and residual from both data (land survey and satellite) is 0.703, 0.722, and 0.015 sequentially. The CBA and regional of both gravity data have the best agreement, but the residual nearly doesn’t have any correlation. This result is because the satellite data has 1-minute grids in resolution, which means the spacing between the gravity data is roughly about 1800 m. With that spacing, the full wavelength that can be observed is more than 3600 m, so anomalies in lower wavelengths usually associated with shallow depths are not good enough to be appropriately measured. Vice versa, the longer wavelengths will be sufficiently provided by satellite. The long-wavelength of gravity data has considerable potential to be used in investigating regional anomalies, such as basement and general geologic mapping. Our results also show that the regional gravity anomaly has high compatibility with geological data.
Generating 1D depth profile of shear-wave velocity from ambient noise cross-correlation: application to Jakarta array
Authors: Ry Rexha V. , Cummins P. R. , Widiyantoro S.
Published: September 2023

In the past decade, cross-correlations of ambient seismic noise have been exploited in various applications to model the shallow-to-deep structure of Earth’s interior through tomographic inversions. The stack of cross-correlations between a 2-station pair represents empirical Green’s function and comprises the information of the subsurface structure between those stations. In practice, noise correlation function (NCF) is analyzed to reconstruct surface wave group or phase velocity dispersion; then, the dispersion data is used to model shear-wave velocity (Vs). This study presents a case for temporary seismic networks deployed in the Jakarta Basin; we applied a two-step routine to obtain a representative 1D Vs profile beneath an array. First, we extracted our array’s average phase velocity dispersion based on the relationship between NCF’s spectra and the Bessel function. Then, we invert for the 1D depth profile of Vs using a transdimensional Bayesian inversion to allow for exploring a number of layers in parameterizations. We successfully generate a 1D Vs profile up to 5 km depth reflecting the regional stratigraphy of the Jakarta Basin. In general, a sedimentary basin fill covers the area reaching a depth of 650 m. We suggest that this simple routine can be undertaken for other ambient noise cross-correlation cases; such a 1D depth profile would be beneficial to be used as a reference model.
Early Analysis of Vulnerability Study in Lake Toba
Authors: Rochim D N
Published: September 2023

Lake Toba is located on the Sumatra Island, Indonesia. The subduction of the Indo-Australian plate dominates the tectonic setting in this region underneath the Eurasian plate. This area has active seismicity, especially from the subduction process in the West. Most rocks in Lake Toba are tuff sediments. This study’s objective is to map the vulnerability index that can be used to identify high damage areas in the region if an intense event occurs. We use 24 three-component seismometers installed around Lake Toba. We gathered good quality recording data for one day on each station. Next, we divided our data into 1 hour and performed the time to frequency domain using the fast Fourier transform. Lastly, we divided the horizontal and vertical components and extracted some parameters such as dominant frequency value and its amplitude. The dominant frequency value ranged from 0.18 to 27.6 Hz, H/V amplification was found to be between 2.84 and 11.9, and shear wave velocity (Vs30) was found to be between 240 and 760 m/s, and the soil vulnerability index (Kg) was found to be between 0.42-43.4. The study area’s highest vulnerability is in the southeast, whereas the study area’s lowest vulnerability is located in the West and North East.
Preliminary Results on Low Frequency Passive Seismic (LFPS) Study in Lake Toba
Authors: Yusami R , Saqina A , Zaky D A , Satiawan S
Published: September 2023

Sumatra Island is an island located in the subduction zone of the Indo-Australian plate towards Eurasia. The geological structure on the island of Sumatra is the Semangko Fault. There is active volcanic activity, such as the Bukit Barisan Mountains, which makes Sumatra Island vulnerable to volcanic eruptions. The study was conducted in Lake Toba, North Sumatra, using earthquake data from the IRIS station. The purpose of this study is to investigate the amplitude in determining the presence of fluid reservoirs (magma) and to analyze the volcanics of the Lake Toba region using the Low Frequency Passive Seismic (LFPS) method by utilizing attributes such as maximum amplitude Vertical-to-Horizontal Spectral Ratio (VHSR), maximum amplitude of Power Spectral Density (PSD) Z, and the maximum amplitude spectrum of the Z component, which are used as indicators to connect the subsurface fluid reservoir by looking at the spectrum curve. Previous research has linked the presence of a reservoir to the peak amplitude spectrum in the vertical component in the frequency range 1-6 Hz. Based on the research results from the analysis of all attribute parameters obtained, the maximum anomaly of the maximum VHSR amplitude spectrum, the maximum PSD Z amplitude, and the maximum Z component amplitude spectrum indicate that the location with the highest subsurface fluid reservoir potential is in the Northwest-Southeast around Lake Toba and Samosir island. These results support previous research. Volcanic activity in Lake Toba is relatively lower because the amplitude spectrum values of all attribute parameters are not too high.
Application of Cross-hole Seismic Tomography to Inferred Cavities Condition.
Authors: Fatkhan  , Ryannugroho Riskiray , Lawrens Fernando , Delliansyah Rendy , Prabowo Billy Sugiartono , Sule Mohammad Rachmat
Published: September 2023

The construction of the Rajamandala hydroelectric power plant civil works has experienced critical problems that arise in the implementation process, with the occurrence of cracks cavities conditions in the headrace tunnel locations. We applied the cross-hole seismic tomography to detect important heterogeneities and mechanical proprieties of the formations between two boreholes in this case inferred cracks cavities condition. The seismic source is inside the borehole “a sparker” and the receivers “hydrophones” are in an adjacent one, the sparker is lowered into the borehole one step at the time. Seismic waves, propagating in the tunnel wall rock, spread widely, and are reflected and refracted when encountering interfaces between rocks with different acoustic impedances. Reflected waves returning to the receivers are recorded. After the processing of the first arrivals of the P waves we obtain a cross section of the seismic velocities in between the two wellbores. With the cross-hole seismic tomography, the basis could be provided to the tunnel construction and parameter adjustments to guarantee the construction safety. Our result shown that there is a weak zone above the tunnel with low Vp zone (~1.2 km/s) may be related to weak zone (may be fracture, unconsolidated rock, and fluid-filled rock or landslide caving). Checker-board resolution test is also conducted to determine the tomogram areas that are reliable to be interpreted. Our challenges are we have poor resolution due to not enough raypath. The Cross-hole seismic tomography can effectively and safely guide the excavation of the tunnel section working surface in combination with reconstructed images and excavation technology.
An Attempt To Invert Tomography Delay Time Problem With Hybrid Lsqr
Authors: Rizkiyana A , Ajeng Belista N
Published: September 2023

Indonesia is situated in Southeast Asia’s active tectonic zone, influenced by the movement of four plates: the Eurasian Plate in the south, the Eurasian Plate in the north, the Philippine Plate, and the Pacific Plate in the northeast. The Tomography approach was used in this work to obtain a stable solution, which was achieved through regularization. Least Square and Hybrid Lsqr are the inversion methods employed. This research aimed to use the IR Tools Package Irhybrid LSQR to investigate inversion tomography with regulatory approaches in 3D. In this study, Matlab is used to perform inversion tomography. Two types of data, real and synthetic, are employed at this stage. The study’s genuine data came from earthquake catalogues from BMKG, MARAMEX, DOMERAPI, and BPPTKG, with depths ranging from 0-658 km and recorded between 20 December 2013 - 6 September 2020, with an area boundary of 110.1 – 110.8. LS -7.8–7.2 BT. The red colour represents the magma reservoir area according to the inversion data. Hybrid LSQR is an iterative approach that is considered stable enough to be used in tomography. When applied to tomographic coding and compared to the most widely used inversion method, Least Square, the results obtained in the least Square have a higher value than Hybrid LSQR.