bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulsed thermoreflectance imaging for thermophysical properties measurement of GaN epitaxial heterostructures
Authors: Liu Zhi-Ke , Yang Guang , Cao Bing-Yang
Published: September 2023

Multilayer heterostructures composed of a substrate and an epitaxial film are widely utilized in advanced electronic devices. However, thermal bottlenecks constrain their performance and reliability, and efficient approaches to comprehensively measure the thermophysical properties of heterostructures are urgently needed. In this work, a pulsed thermoreflectance imaging (PTI) method is proposed, which combines the transient temperature mapping of thermoreflectance thermal imaging with transient pulsed excitation. By executing merely three transient tests, six thermophysical properties, including the film thermal conductivity and specific heat capacity, the substrate thermal conductivity and specific heat capacity, the film–substrate thermal boundary resistance, and the equivalent thermal conductivity of the insulating layer, can be simultaneously measured in a heterostructure sample. The proposed method applies a pulsed current excitation to a metal heater line on the sample surface and utilizes the thermoreflectance thermal imaging system to measure the temperature of different spatial regions on the sample surface at different time windows. The temporal and spatial variation information of the temperature field is then extracted and combined with finite element method inversion calculation to obtain the thermophysical properties of heterostructures. To validate the accuracy and reliability of this method, we conducted measurements on a GaN-on-SiC heterostructure sample and obtained thermophysical properties consistent with the representative literature data that have previously been reported. The proposed PTI method, characterized by its high sensitivity, demonstrates good efficiency and reliability in conducting comprehensive thermophysical property characterization of GaN epitaxial heterostructures.
Comments on “Thermal solitons along wires with flux-limited lateral exchange” [J. Math. Phys. 62, 101503 (2021)]
Authors: Jordan P. M.
Published: September 2023

A derivation error in the article cited in the title of this Comment is pointed out and corrected. In addition, the Maxwell–Cattaneo based model assumed therein is extended to include expected Joule heating effects; an alternative theory of second-sound that allows the same modeling to be performed, but with fewer assumptions, is noted and applied; and the difference between ordinary solitary waves and solitons is recalled.
Chirality induced spin selectivity in chiral hybrid organic–inorganic perovskites
Authors: Wang Jingying , Mao Baorui , Vardeny Zeev Valy
Published: September 2023

Chiral materials exhibit many interesting physical properties including circular dichroism, circularly polarized photoluminescence, and spin selectivity. Since its discovery, chirality-induced spin selectivity (CISS) has been demonstrated in many chiral material systems, which indicates promising applications in spintronic devices. Thus, searching for compounds that possess both sizable chirality and excellent spin transport properties is in order. Hybrid organic–inorganic perovskites have attracted intensive research interest due to their long carrier lifetime, high carrier mobility, chemically tunable electronic properties, and long spin lifetime, which make this emerging class of semiconductors promising candidate for spintronics. Moreover, hybrid perovskites integrate inorganic octahedral framework and organic ligands, which may introduce chirality into the materials, especially in quasi-two-dimensional structures. Recently, CISS has been observed in 2D chiral hybrid perovskites, showing the spin filtering effect. Studies of CISS in chiral hybrid perovskites not only help deepen our understanding of CISS mechanism but also shed new light on designing novel spintronic devices. In this review, we summarize the state-of-the-art studies of CISS effect in 2D chiral hybrid organic–inorganic perovskites system. We also discuss the remaining challenges and research opportunities of employing CISS in next-generation spintronic devices.
A novel hydraulic fracturing model for the fluid-driven fracture propagation in poroelastic media containing the natural cave
Authors: Jin Jie , Wang Xiaoqiang , Liu Xiaohua , Xu Yanmei , Lu Detang
Published: September 2023

Hydraulic fracturing is an efficient technology to extract hydrocarbon within natural caves. However, these caves can markedly affect the fracture propagation behavior. This paper proposes a novel hydraulic fracturing model to simulate the fracture propagation in poroelastic media containing the natural cave, utilizing the strengths of the phase-field method. By coupling the Reynolds flow with cubic law in fracture domain, free flow in cave domain, and low-permeability Darcy flow in reservoir domain, the fracture-cave-reservoir flow governing equations are established. The Biot poroelasticity theory and fracture width are the links of hydro-mechanical coupling. The smooth phase-field is introduced to diffuse not only the sharp fracture but also the sharp cave edge. The fully coupling model is solved by a staggered scheme, which independently solves the pressure field and displacement field in inner cycle, and then independently solves the phase field in outer cycle. The proposed model is verified by comparing with the Khristianovic–Geertsma–de Klerk (KGD) model and Cheng's hydraulic fracturing model. Then, the interaction between hydraulic fracture and natural cave is investigated through several two-dimensional and three-dimensional cases. The result shows that the cave effect can make the hydraulic fracture deflect and raise its propagation velocity. Increasing the fracture-cave distance, injection rate, and in situ stress difference can all decline the cave effect. The displayed cases also substantiate the capability and efficiency of the proposed model.
Response of a supersonic turbulent boundary layer to different streamwise adverse pressure gradients
Authors: Wen Jinghao , Wang Qiancheng , Wei Feng , Lin Juncan , Zhou Yanmei , Luo Xin
Published: September 2023

An adverse pressure gradient (APG) has an impact on the boundary layer, increasing the turbulent intensity of the layer. The mean and turbulent properties of the turbulent boundary layer on a flat plate with different APGs were investigated at Mach 2.7 in the present work utilizing the particle image velocimetry and nanoparticle-based planar laser scattering techniques. According to analysis, the changing trends of boundary layer parameters are different depending on whether the local mainstream velocity or freestream velocity of the wind tunnel is used to normalize. Using the former might make the enhanced effect of the rising APG more visible. With the rise in APG, the principal strain rate, turbulent fluctuation, Reynolds stress, and turbulence production in the boundary layer all increased, while the turbulent boundary layer's thickness dropped. Furthermore, the heightened upward ejection and downward sweep events caused the streamwise turbulence intensity to reach its outer peak under the influence of strong APG. The characteristics of the spanwise vortex in the boundary layer are investigated in conjunction with the probability density function analysis. The growing APG, which primarily promote negative vorticity, can strengthen the rotational strength of spanwise vortices, which are a component of hairpin vortices. As APG rises, the number of small-scale vortices in the boundary layer increases and the fractal dimension grows. The increase in small-scale vortices tends to induce strong transportation and promotes turbulence intensity. Further investigation reveals that the increased volume change caused by the enhanced compression effect with increasing APG exacerbated the vorticity.
Flexible centrifugally spun PVP based SnO2@carbon nanofiber electrodes
Authors: Yanilmaz Meltem , Abdolrazzaghian Elham , Chen Lei , Atıcı Bülin , Kim Juran
Published: September 2023

Sodium-ion batteries (SIBs) have attracted significant attention because of the abundant resource and low-cost of sodium. Furthermore, flexible and wearable functional electronics have been presented as one of the most important emerging technology. Carbon nanofibers are promising candidates for flexible electrodes due to their high electronic conductivity and high surface area, while it is vital to use non-petroleum-based polymers considering environmental concerns. Developing flexible nanostructured electrodes by using environment friendly polymers with a fast and low-cost technique is critical to develop high performance flexible electronics. Electrochemical properties are influenced by the morphology and average fiber diameters of nanofibers. In this study, poly(vinylpyrrolidone) (PVP) solutions with various concentrations and two different solvent systems (ethanol/water and ethanol/dimethylformamide) were successfully spun into nanofibers by the fast, safe, low-cost, and environment friendly technique of centrifugal spinning. The effect of solvent system and solution concentration was investigated by using scanning electron microscopy images, and the average fiber diameters varied from 436 nm to 3 µm. Moreover, nine different heat treatments were studied, and the effect of time and temperature during stabilization and carbonization on the morphology of carbon nanofibers (CNFs) was investigated. Furthermore, flexible carbon nanofibers were fabricated and used as binder-free anodes in sodium-ion batteries. In order to enhance the electrochemical properties of flexible CNFs, flexible SnO2@CNFs were fabricated by combining centrifugal spinning and heat treatment. The electrochemical performance of the flexible SnO2@carbon nanofiber anodes was evaluated by conducting galvanostatic charge/discharge tests and cycling voltammetry. A high rate of performance was also presented. The high reversible capacity of 400 mA h/g was delivered when flexible centrifugally spun PVP based SnO2@carbon nanofiber electrodes were used in SIBs.
On using Helmholtz-type resonance to reduce the size of dual-purpose offshore oscillating water column wave energy converters
Authors: Cui Lidong , Sergiienko Nataliia , Cazzolato Benjamin , Leontini Justin , Tothova Danica , Cannard Patrick , Spinks Nathan , Manasseh Richard
Published: September 2023

Oscillating water column (OWC) devices with Helmholtz resonator features are analyzed with semi-analytical, numerical, and experimental techniques. Conventionally, an OWC is a type of wave energy converter that consists of a duct with one end submerged, where the device's peak frequency is tuned by the length of the submerged duct. This leads to large devices when the desired peak frequency is low. The size of a conventional OWC can be reduced significantly by synthesizing features of Helmholtz resonators into it, such as using a narrow entrance. When integrated with a breakwater, it has been shown that the Helmholtz-type OWC can generate power while protecting the coastline from low-frequency ocean waves, making them dual-purpose. A systematic study of dual-purpose offshore Helmholtz-type OWC is still wanting. This study considers offshore “buoy-like” Helmholtz-type OWCs by a fast and heuristic semi-analytical model, which incorporated viscosity-related damping by empirical terms. The model shows that the Helmholtz-type OWCs have the potential to protect the coastline from low-frequency (long wavelength) waves, by producing a wide wave shadow behind them. The semi-analytical model is validated against the boundary element method (BEM), as well as experiments. The first experiment compares a Helmholtz-type OWC and a conventional OWC of the same size but different peak frequencies; the second compares a larger conventional OWC with a smaller Helmholtz OWC, which is tuned to have the same peak frequency as the former. In both cases, the semi-analytical model and the results from BEM agree well with the experiments.
A simulation study of electron-scale turbulence generation by nonlinear wave–wave interaction in laser-produced plasmas
Authors: Singh Indraj , Uma R. , Sharma R. P.
Published: September 2023

A laboratory simulation of a model based on the nonlinear interaction of plasma waves is presented to study the electron-scale magnetic turbulence in the magnetized plasma. In this perspective, the model equations of the Trivelpiece–Gould (TG) mode and extraordinary mode (pump wave) are developed, taking the relativistic change in electron mass and the ponderomotive force into account. Laboratory simulations utilizing the pseudo-spectral method along with the predictor–corrector scheme and finite difference method are performed to solve the formulated coupled model equations. The propagation angle (θ) of the TG mode from the magnetic field affects the dispersive properties of the dynamics (TG mode), which, in turn, impact the density perturbation, scale size of the filamentary structures, density harmonics, magnetic field enhancement, and the spectral index of the turbulence generation. The simulation results reveal that the observed turbulent spectra resemble the magnetic turbulence reported in various studies of the interaction of the intense laser with plasma at the laboratory astrophysics scale relevant to astrophysical events. A simplified model in the paraxial limit is also given to understand the effect of the propagation direction (angle of propagation θ) of the TG mode on the localized structures of the pump laser beam in the magnetized plasma.
Self-interaction and transport of solvated electrons in molten salts
Authors: Pegolo Paolo , Baroni Stefano , Grasselli Federico
Published: September 2023

The dynamics of (few) electrons dissolved in an ionic fluid—as when a small amount of metal is added to a solution while upholding its electronic insulation—manifests interesting properties that can be ascribed to nontrivial topological features of particle transport (e.g., Thouless’ pumps). In the adiabatic regime, the charge distribution and the dynamics of these dissolved electrons are uniquely determined by the nuclear configuration. Yet, their localization into effective potential wells and their diffusivity are dictated by how the self-interaction is modeled. In this article, we investigate the role of self-interaction in the description of the localization and transport properties of dissolved electrons in non-stoichiometric molten salts. Although the account for the exact (Fock) exchange strongly localizes the dissolved electrons, decreasing their tunneling probability and diffusivity, we show that the dynamics of the ions and of the dissolved electrons are largely uncorrelated, irrespective of the degree to which the electron self-interaction is treated and in accordance with topological arguments.
Regulatory T cells play a crucial role in maintaining sperm tolerance and male fertility
Authors: Barrachina Ferran , Ottino Kiera , Elizagaray Maia Lina , Gervasi Maria Gracia , Tu Leona J. , Markoulaki Styliani , Spallanzani Raul G. , Capen Diane , Brown Dennis , Battistone Maria Agustina
Published: September 2023

Regulatory T cells (Tregs) modulate tissue homeostatic processes and immune responses. Understanding tissue-Treg biology will contribute to developing precision-targeting treatment strategies. Here, we show that Tregs maintain the tolerogenic state of the testis and epididymis, where sperm are produced and mature. We found that Treg depletion induces severe autoimmune orchitis and epididymitis, manifested by an exacerbated immune cell infiltration [CD4 T cells, monocytes, and mononuclear phagocytes (MPs)] and the development of antisperm antibodies (ASA). In Treg-depleted mice, MPs increased projections toward the epididymal lumen as well as invading the lumen. ASA-bound sperm enhance sperm agglutination and might facilitate sperm phagocytosis. Tolerance breakdown impaired epididymal epithelial function and altered extracellular vesicle cargo, both of which play crucial roles in the acquisition of sperm fertilizing ability and subsequent embryo development. The affected mice had reduced sperm number and motility and severe fertility defects. Deciphering these immunoregulatory mechanisms may help to design new strategies to treat male infertility, as well as to identify potential targets for immunocontraception.
Modal may in requests
Authors: Elsweiler Christine
Published: September 2023

This study applies House’s (1996, 2005) dimensions of cross-cultural differences as a diagnostic tool to investigate regional variation regarding two
pragmalinguistic requestive patterns with may in Scottish and English non-private letters (1500 to 1700). The
dimensional scheme proves a useful tool for explaining similarities and differences in the requestive behaviour in the two
varieties. It is shown that, in the sixteenth century, grounders with may are part of a set of downgrading
devices employed by letter-writers to counteract the directness and self-orientation particularly of performative requests in both
the Scottish and the English correspondence. Moreover, the dimensional analysis explicates the cross-varietal differences
regarding may in the seventeenth century correspondence by linking the rise of mitigating may in
performative requests in the Scottish letters to the increased self-orientation towards the letter-writer, which is not
counter-balanced by other downgraders.
Contrasting Transport Performance of Electron- and Hole-Doped Epitaxial Graphene for Quantum Resistance Metrology
Authors: Wan 万 Xinyi 歆祎 , Fan 范 Xiaodong 晓东 , Zhai 翟 Changwei 昌伟 , Yang 杨 Zhenyu 镇宇 , Hao 郝 Lilong 立龙 , Li 李 Lin 林 , Lu 鲁 Yunfeng 云峰 , Zeng 曾 Changgan 长淦
Published: September 2023

Epitaxial graphene grown on silicon carbide (SiC/graphene) is a promising solution for achieving a high-precision quantum Hall resistance standard. Previous research mainly focused on the quantum resistance metrology of n-type SiC/graphene, while a comprehensive understanding of the quantum resistance metrology behavior of graphene with different doping types is lacking. Here, we fabricated both n- and p-type SiC/graphene devices via polymer-assisted molecular adsorption and conducted systematic magneto-transport measurements in a wide parameter space of carrier density and temperature. It is demonstrated that n-type devices show greater potential for development of quantum resistance metrology compared with p-type devices, as evidenced by their higher carrier mobility, lower critical magnetic field for entering quantized Hall plateaus, and higher robustness of the quantum Hall effect against thermal degeneration. These discrepancies can be reasonably attributed to the weaker scattering from molecular dopants for n-type devices, which is further supported by the analyses on the quantum interference effect in multiple devices. These results enrich our understanding of the charged impurity on electronic transport performance of graphene and, more importantly, provide a useful reference for future development of graphene-based quantum resistance metrology.
The c-completion of Lorentzian metric spaces
Authors: Burgos Saúl , Flores José L , Herrera Jónatan
Published: September 2023

Inspired by some Lorentzian versions of the notion of metric and length space introduced by Kunzinger and Sämman (2018 Ann. Glob. Anal. Geom.
54 399–447), and more recently, by Müller (2022 arXiv:2205.01617), and Minguzzi and Suhr (2023 arXiv:2209.14384), we revisit the notion of Lorentzian metric space in order to later construct the c-completion of these general objects. We not only prove that this construction is feasible in great generality for these objects, including spacetimes of low regularity, but also endow the c-completion with a structure of Lorentzian metric space by itself. We also prove that the c-completion constitutes a well-suited extension of the original space, which really completes it in a precise sense and becomes sensible to certain causal properties of that space.
Potential and Feshbach s-wave resonances in coupled atomic collision channels
Authors: Andrade-Sánchez G , Romero-Rochín V
Published: September 2023

We discuss s-wave scattering in an atomic binary collision with two coupled channels, tunable by an external magnetic field, one channel open and the other closed for the incident energies considered. The analysis is performed with a stylized model of square-well potentials. This simplification allows for a pedagogically thorough discussion of the different scattering resonances that appear in coupled channels. One of them, the potential resonances at vanishing energy, occurs as a bound state of the coupled system emerges, in turn, tuned at a very precise value of the external field. The other resonances, described by Feshbach theory, occur when the incident energy is near a bound state of the closed channel, as if it were decoupled from the open channel. These resonances exist for values of the external field above a particular threshold value. Besides the potential intrinsic value of this study in a quantum mechanics course, as the analysis can be performed with minor numerical calculations, it is also an aid for the understanding of current research advances in the exciting field of ultracold gases.
Use of life cycle assessment (LCA) to advance optimisation of radiological protection and safety
Authors: Wattier Bryanna D , Martinez Nicole E , Carbajales-Dale Michael , Shuller-Nickles Lindsay C
Published: September 2023

Life cycle assessment (LCA) is a modelling technique used to determine the cradle-to-grave environmental and human health impacts from the production of a good or the provision of a service. Radiological protection may benefit from employing tools like LCA to obtain a broader perspective and enable comparison with analyses of non-radiological systems. Despite structural similarities to other well-established decision-aiding techniques (DATs), the impact assessment within LCA (i.e. LCIA) is not commonly used in the optimisation of radiological protection process. This paper provides a brief review of LCA, including LCIA, along with more traditional DATs (such as multi-attribute utility analysis) used in the optimisation process for comparison. Basic concrete shielding was considered as a simple, illustrative example; concrete attenuates emissions from a radiation source but is also associated with a financial cost as well as costs with respect to energy, material, and water use. LCA offers quantification of these and other key resources (termed ‘impact categories’). Ultimately, we offer that, depending on the circumstance, LCA can be a useful tool in radiological protection decision-making, complementing existing techniques.
A bidirectional long short-term memory network for electron density diagnostic with double probe
Authors: Wang Jin , Zhou Yu , Du Qing Fu , Chen Jia Yu , Xing Zan Yang , Li Yan Hui , Sun Qi , Guo Xin , Xie Xin Yao , Liu Zhen Ping , Li Guo Jun , Zhang Qing He
Published: September 2023

The double probe method is a plasma in situ diagnostic technology. Compared with Langmuir single probe, it has less influence on the background plasma and can obtain relatively accurate results. However, it can only collect some high-energy electrons in the plasma, and cannot directly measure the electron density (N
e). In this paper, a double probe N
e diagnosis approach based on Bidirectional Long Short-Term Memory (BLSTM) is proposed. After the training is completed, the accurate prediction of N
e can be realized by using the double probe data, which solves the problem that the double probe cannot directly measure N
e. In the plasma simulation environment of the laboratory, the plasma source is controlled to generate plasma with different densities, the current–voltage (I–V) characteristic data of the double probe at the same position are used as features, and the N
e calculated by the triple probe is used as the label to train the BLSTM model. The mean square error is used as the loss function, the root mean square error (RMSE) and the prediction accuracy (Acc) are used as the evaluation indicators. The BLSTM network is evaluated according to the evaluation indicators and the hyperparameters are adjusted. After about 100 iterations, the RMSE of the BLSTM network to N
e can be reduced to about 0.03. The final network is evaluated on a separate test set. The results show that in the range of 2 × 1013m−3–3 × 1014 m−3, the model can predict N
e more than 95% accurately. This approach extends the application of the double probe method and is of great significance for improving the accuracy of plasma diagnostic methods. If it is applied to ionospheric plasma diagnosis, it can reduce the amount of data collected by the probe and improve the spatial resolution of ionospheric detection.
Federated transfer learning with consensus knowledge distillation for intelligent fault diagnosis under data privacy preserving
Authors: Xue Xingan , Zhao Xiaoping , Zhang Yonghong , Ma Mengyao , Bu Can , Peng Peng
Published: September 2023

Fault diagnosis with deep learning has garnered substantial research. However, the establishment of a model is contingent upon a volume of data. Moreover, centralizing the data from each device faces the problem of privacy leakage. Federated learning can cooperate with each device to form a global model without violating data privacy. Due to the data distribution discrepancy for each device, a global model trained only by the source client with labeled data fails to match the target client without labeled data. To overcome this issue, this research suggests a federated transfer learning method. A consensus knowledge distillation is adopted to train the extended target domain model. A mutual information regularization is introduced to further learn the structure information of the target client data. The source client and the extended target models are aggregated to improve model performance. The experimental results demonstrate that our method has broad application prospects.
Retrieval of tropospheric delays from multi-GNSS observations in the polar region: effect factors and performance
Authors: Li Weiwei , Li Chunlei
Published: September 2023

Precise point positioning (PPP) technique is practical in estimating the zenith tropospheric delay (ZTD). To comprehensively study the factors affecting its accuracy in the polar region, different elevation cutoff angles for each single system and multi-system combination, different tropospheric mapping functions, tropospheric gradients and also seasonal variations are assessed. Meanwhile, European Centre for Medium-Range Weather Forecasts (ECMWF) products are adopted to validate the accuracy of PPP-derived ZTD. The results show that the root mean square (RMS) value of the estimated ZTD and ECMWF products is around 4 mm when the elevation cutoff angle is set to 10 degrees or less. From the view of system combination, it improves the ZTD accuracy in comparison with each individual system. The dual-system combination has 21.8%, 19.0% and 19.1% improvements in its ZTD accuracy compared with the Global navigation satellite system (GLONASS), Beidou navigation satellite system (BDS) and Galileo satellite navigation (GAL) systems. The four-system combination can reach 7.7% further improvement in ZTD estimation than that of the dual-system. For mapping functions, Vienna mapping function 3 (VMF3) function has the best accuracy among the four mapping functions of Niell mapping function (NMF), global mapping function, VMF1 and VMF3, while NMF does not perform as well as others. Considering the tropospheric gradients could get higher accuracy in ZTD estimation than ignoring them. The tropospheric delay estimated in winter is more accurate than that in summer and specifically the RMS value in winter is about 0.9 mm lower than that in summer. Overall, from investigation the estimation of ZTD in the polar region can be optimally handled with a multi-system and VMF3 mapping function at an elevation cutoff angle of 7°, considering the tropospheric gradients.
A personalized Monte Carlo study of tumor and critical organ doses for trans-arterial radioembolization patients
Authors: Bozkurt Ahmet , Toker Gul Demir , Erkilic Metin
Published: September 2023

Trans-arterial radioembolization (TARE) is an intra-arterial treatment method for liver malignancies. In this procedure, the therapeutic tumor dose is significant for predicting the treatment effectiveness while the dose absorbed in an organ at risk provides an understanding of its tolerance to radiation. This study proposes a Monte Carlo (MC) approach for determining absorbed organ doses for patients undergoing TARE treatment. The technique is based on the use of a voxel-based partial body model generated for each patient from his/her anatomical image data to represent the critical body structures more realistically. These structures are first segmented from image slices to create an image block which is then incorporated into a radiation transport package (MCNP6.2) to perform MC simulations. When used along with the parameters specific to a patient’s treatment, such as lung-shunt factor, tumor-to-normal liver ratio, fractional uptakes, and administered activity, this approach allowed more accurate simulation of radiation interactions and hence provided absorbed doses specific to a TARE patient. The MC method also calculated the absorbed doses in organs or tissues that were close to target tissues for which the Medical Internal Radiation Dose Committee (MIRD) formalism makes no predictions. MIRD calculations were found to overestimate the absorbed doses by as much as 11% in lungs, 5% in liver, and 20% in tumor volumes. This raises concerns about the treatment’s efficacy when estimating the correct activity to be administered to a patient. When each patient simulation was repeated with a 90Y source spectrum to reflect the distribution of varying beta energies, the liver and the lungs were observed to receive relatively lower doses than those obtained with monoenergetic beta particles. Thus, it can be stated that the approach adopted in this study offers a more precise model of the patient’s critical tissues and serves as a personalized dosimetric tool for TARE treatment planning.
Extensive entropy: the case of zero entropy defect
Authors: Livadiotis G , McComas D J
Published: September 2023

This paper shows that the Rényi and Boltzmann-Gibbs (BG) extensive entropies share the same functional relationship with the nonextensive entropy associated with kappa distributions, which coincides with the well-known Havrda/Charvát/Daróczy/Tsallis (HCDT) entropy. We find that while the relationship between kappa/HCDT and Rényi entropies is merely a mathematical identity between their entropic statistical definitions, the relationship between kappa/HCDT and BG entropies is based on their thermodynamic connection. The latter connects the entropy between a system characterized by correlations among their all constituents (kappa/HCDT entropy) and the entropy of the same system but with no correlations among their constituents (BG entropy). The origin of this relationship, and its connection with thermodynamics, is examined using the concept of entropy defect, that is, the decrease in a system’s entropy caused by the presence of long-range correlations among its constituents; in the limiting case of zero correlations, the entropy defect vanishes and the entropy becomes extensive and expressed by the BG formulation.
Influence of microstructure on dielectric function and plasmonic properties of silver nanoparticles grown by solid state dewetting: a spectroscopic ellipsometry study
Authors: Gangwar Manvendra Singh , Agarwal Pratima
Published: September 2023

This work reports the microstructure influence on dielectric function and plasmonic properties of silver nanoparticles (Ag NPs). Ag NPs with varying microstructures were grown on corning glass substrate by solid-state dewetting (SSD) of sputtered silver thin films deposited by varying RF power. Dielectric function and plasmonic properties of Ag NPs were investigated from spectroscopic ellipsometry (SE) data using a quite unique model in terms of the combination of different oscillators. Drude–Lorentz model along with two Gauss oscillators was used to account for intraband, interband transitions and different modes of localized surface plasmon resonance (LSPR) of Ag NPs. It was observed that peak of imaginary part of pseudo dielectric function, which is due to LSPR of Ag NPs, shifted towards the lower energy at higher RF power due to increase in thickness of precursor films which subsequently resulted in to increase in particle size. A shift in the LSPR peak in absorbance spectra in UV–Vis-NIR spectroscopy was also observed. No LSPR peak is observed in SE or UV–Vis absorbance spectra for thick films deposited at high RF power due to the presence of continuous silver film even after annealing. This change in microstructure from nanoparticle formation to continuous films is also reflected in the values of void fraction and surface roughness calculated from SE using Bruggeman Effective Medium Approximation (BEMA). Field Emission Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), and X-ray diffraction (XRD) were used to probe the microstructure of Ag NPs. Root mean square (RMS) roughness evaluated from AFM matched well with surface roughness measured from SE.
Characterization of incompletely coated D-shaped PCF-SPR refractive index sensors
Authors: Jiang Haoran , Shen Tao , Feng Yue , Liu Chi , Liu Xin , Han Jiaru , Hujun Tang
Published: September 2023

To reduce the complexity of the sensor structure and improve the sensitivity of refractive index (RI) measurement, a D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) RI sensor with incomplete coating of gold-tantalum pentoxide (Au-Ta2O5) on the surface is proposed. When the coating width is 3.1 μm, the sensor can detect RI samples ranging from 1.35 to 1.41 in the ultra-wide near-infrared (NIR) region of 1100–2100 nm wavelength. Its maximum wavelength sensitivity is 20,000 nm RIU−1, maximum amplitude sensitivity is 2817.7 RIU−1, resolution is

5
×
10

−
6

RIU, and figure of merit (FOM) is 333.3 RIU−1. This sensor can be widely used in biological tissue detection. For this type of incomplete coated D-shaped sensor, the coating material and structural parameters not only affect the performance of the sensor, but also change the RI detection range, which has been ignored or not mentioned in previous literature on PCF-SPR sensors. Therefore, the reasons for the change of RI detection interval and negative optimization caused by structural parameters were analyzed, and two different sensors with different coating widths were finally obtained, which can achieve high sensitivity sensing in their respective detection intervals. The detailed research results expand the understanding of the SPR phenomenon in D-shaped PCF and provide theoretical guidance for adjusting and improving the detection performance of PCF-SPR sensors.
From WIMPs to FIMPs with low reheating temperatures
Authors: Silva-Malpartida Javier , Bernal Nicolás , Jones-Pérez Joel , Lineros Roberto A.
Published: September 2023

Weakly- and Feebly-Interacting Massive Particles (WIMPs and FIMPs) are among the best-motivated dark matter (DM) candidates. In this paper, we investigate the production of DM through the WIMP and FIMP mechanisms during inflationary reheating. We show that the details of the reheating, such as the inflaton potential and the reheating temperature, have a strong impact on the genesis of DM. The strong entropy injection caused by the inflaton decay has to be compensated by a reduction of the portal coupling in the case of WIMPs, or by an increase in the case of FIMPs. We pinpoint the smooth transition between the WIMP and the FIMP regimes in the case of low reheating temperature. As an example, we perform a full numerical analysis of the singlet-scalar DM model; however, our results are generic and adaptable to other particle DM candidates. Interestingly, in the singlet-scalar DM model with low-reheating temperature, regions favored by the FIMP mechanism are already being tested by direct detection experiments such as LZ and XENONnT.
Analyzing problematic issues of building information modeling (BIM) implementation by contractors
Authors: Kiet Tran Tuan , Kha Tran Thi , Thuan Truong Cong
Published: September 2023

Building information modeling (BIM) is the current and future trend in the implementation of projects. Even though BIM can benefit all project participants in various aspects, implementing BIM in practice is often encountered with various difficulties stemming from different sources, especially BIM implementation at the organizational level. This is because the ecosystem of BIM organizations are different from that of conventional ones. This study investigates the problematic issues concerning BIM implementation by construction contractors. It first compiled and identified 32 major problematic issues concerning contractors’ BIM implementation. The necessary data were compiled from extensive literature review and collected through a questionnaire survey. By applying factor analysis, this study deduced eight underlying dimensions of the challenges of BIM implementation. These results help contractors realize problematic issues while implementing BIM at the organizational level. They can subsequently choose appropriate responsive measures to address such problems. This can clearly enhance the achievement of BIM implementation in practice and guide contractors to optimization in schedules and distribute resources.
Identify benzene pollution, sources of benzene emission and suggest mitigation measures for Ho Chi Minh City, Vietnam
Authors: Bang Ho Quoc , Khue Vu Hoang Ngoc , Nguyen Thoai Tam , Huynh Thi Thao Nguyen
Published: September 2023

In Ho Chi Minh City (HCMC), benzene concentration was higher than the benzene standard of Vietnam technical regulation for ambient air. However, there is a lack of consideration for benzene sources and mitigation suggestions. This study aims (1) to analyze benzene concentration in HCMC and (2) to calculate benzene emission from primary sources to identify the contribution of benzene from the main sources. Besides, we gave measures to reduce benzene pollution. Our case study is in Ho Chi Minh City (HCMC), Vietnam. Firstly, we analyzed benzene concentration data from the Department of Environment and Resources. The data included 30 sampling locations in Ho Chi Minh City from familiar pollution sources: traffic (19 locations), industry (4 locations), resident areas (4 locations), and ambient regions (3 locations). Secondly, we used benzene emission results to identify the primary sources. Thirdly, we suggested mitigation measures to reduce the benzene concentration in HCMC. Compared to the National technical regulation of hazardous substances in the ambient air of Vietnam (QCVN 06:2009/BTNMT), the benzene concentration exceeded the Vietnamese standard. Significantly, the traffic had the highest contribution, up to 90% of total benzene emission, followed by industry and residential activity. Our findings gave a comprehensive picture of benzene pollution and the contribution of primary sources. We also suggested ten solutions to reduce benzene concentration in HCMC.The results can help the local government’s decision to focus to the significant sources and reduce the benzene pollution in HCMC.
Estimating the Chlorophyll-a in the Nha Trang Bay using Landsat-8 OLI data
Authors: Hieu Nguyen Trinh Duc , Tri Nguyen-Quang , Huan Nguyen Huu , Dien Tran Duc , Tran Nguyen Dang Huyen , Lien Nguyen Phuong , Van Tran Thi
Published: September 2023

The pigment chlorophyll-a (Chl-a) is used to evaluate aquatic ecological health. Using remote sensing techniques to estimate this pigment and spatially mapping its distribution becomes essential for measuring and assessing water quality in coastal areas. Nha Trang Bay is famous not only for its scenery but also for its biodiversity values, especially the existence of coral reefs. In this study, Landsat-8 OLI was taken on June 3, 2015, and field measurements of Chl-a at 13 survey sites from June 6-8, 2015, were used to build a local algorithm to monitor the spatio-temporal distribution of Chl-a content in Nha Trang Bay. The ACOLITE processor was employed for the atmospheric modification of Landsat-8 OLI images to obtain atmospherically corrected surface reflectance products. Four types of simple regression models, including linear, exponential, logarithmic, and power models, were used to describe the relationship between the in-situ measurement of Chl-a and remote sensing reflectance of Landsat-8 OLI data. The results of correlation analysis have shown a statistically significant relationship between field measurement of Chl-a concentration and the remote sensing reflectance ratio of Landsat-8 band 3 versus band 2 using an exponential model with a coefficient of determination of 0.88 (p < 0.001) and root mean square error (RMSE) of 0.40 mg/m3. This empirical relationship was applied to map the spatial distribution of Chl-a concentration from 27 cloudless Landsat-8 OLI images from 2013 to 2021. The spatio-temporal distribution of Chl-a indicated that the Chl-a concentration in the Bay has a low value (less than 1 mg/m3). However, this concentration becomes high in the coastal areas (greater than 1 mg/m3) and the Cai and Tac rivers (greater than 2 mg/m3). It is also noted that the content of Chl-a in the rainy season is fairly higher than in the dry season, by an average of 0.68 mg/m3 and 0.53 mg/m3, respectively. This research highlights that Landsat-8 OLI data can be an effective and valuable tool in monitoring Chl-a for coastal areas.
Modelling migration of ammonium ion through landfill bottom barriers subjected to elevated temperature and dry-wet cycles, a case study in southern Hanoi, Vietnam
Authors: Hoai T T , Nhuan M T , Mukunoki T , Dung T T , Linh L T K
Published: September 2023

Geosynthetic clay liners and compacted clay liners are common bottom barriers in landfills. One of the important steps in barrier design is to evaluate the effectiveness of the bottom barrier system in practical conditions based on modelling contaminant migration. This study simulates the migration of ammonium ions through proposed bottom barriers for design under consideration of the southern Hanoi area’s temperature and geohydrology conditions, then evaluates potential impacts on normalized ammonium concentration in groundwater. Proposed bottom barriers include geosynthetic clay liner and compacted clay liner constituting from local soils. The results indicated the reclamation of locally natural soils and geosynthetic clay liner (GCL) placement was approximately 5.2 and 13.4 times more effective in slowing ammonium migration than natural soil, respectively. Compacted clay liner of natural soils exhibited few impacts from elevated temperature. However, being sensitive to an elevated temperature at 50°C, the barrier performance of GCL caused the peak normalized ammonium concentration in groundwater to be 4.2 times higher than normal conditions. Notably, normalized ammonium concentration in groundwater increased 29 times when the geosynthetic clay liner was exposed to 2 dry-wet cycles with ammonium solution. These results provided useful references for designers and engineers to consider in selecting barrier materials in the new landfill.
Use of hydrogeochemical tools to evaluate seawater intrusion: a case study of Upper Pliocene Aquifer in the Ca Mau Peninsula, Vietnam
Authors: Van Le Thi Thuy , Thang Chau Hong
Published: September 2023

Groundwater resources have been withdrawn significantly to meet the demands of agricultural economic development in the Ca Mau Peninsula, Mekong River Delta. As a result, aquifers face the risk of groundwater levels decline and high salinization potential. This study uses the groundwater quality index (GQI) and hydrochemical facies evolution diagram (HFE-D) to assess the hydrochemical characteristics and salinization potential of the Upper Pliocene aquifer (n2
2), which is one of the two most exploited aquifers in the Mekong River Delta. A total of 6 monitoring wells were used to observe groundwater level and water quality from 2017 to 2020. The GQI results ranged from 33.38 to 75.61, indicating that groundwater in Hau Giang and Soc Trang areas is salinized. The spatial distribution results of HFE-D stated that the boundaries of intrusion and freshening have varied in space and time. Specifically, the Upper Pliocene aquifer has been in the process of seawater intrusion. The freshwater area in the Ca Mau has been gradually shrinking in the East Sea area faster than the West Sea area. The displacement speed of the intrusion and freshening boundary varied considerably from 0.04 to 0.67 km/year from 2017 to 2020.
Enhanced performances of Fischer-Tropsch catalysts modified with Re as a promoter and supported on various structured materials
Authors: Giang Nguyen Thi Chau , Luong Nguyen Huu , Thoa Dao Thi Kim , Thuan Huynh Minh , Huan Nguyen Manh
Published: September 2023

This paper presents enhanced performances of Fischer-Tropsch (F-T) catalysts modified with Re as a promoter and supported by various structured materials. The traditional Fe-Co based catalyst was prepared by the simultaneous impregnation and then application of the wash-coating slurry method to coat the catalyst on structured materials, including monolith and metallic foams. Their physicochemical properties of the catalysts were characterized by Brunauer–Emmett–Teller specific surface area, and hydrogen temperature programmed reduction. The reaction was carried out at the temperature of 250°C, the pressure of 20 bar, and GHSV of 3600 mL.g−1.h−1. It has been shown that the efficiency of the F-T synthesis is significantly improved by both Re modification and structured material application to its traditional catalyst. It is interesting that the catalyst modification resulted in both decreasing gas formation and improving C5+ yield. In the presence of Re as the catalytic promoter, CO conversion and C5+ yield increased by 49% and 50%, respectively. Furthermore, the application of structured materials brought further enhancement in the catalyst performance by an additional 23% increase in both CO conversion and C5+ yield. All catalysts have been observed to be stable during 24 hours on stream.
Fabrication of composite aerogels from waste tires and fly ash for thermal and acoustic insulation applications
Authors: Thi Le Cuc , Nguyen Phuc Tran Thien , Nguyen Thao Thi Thu , Truong Thinh Quoc , Nguyen Tu Minh , Huynh Ha Ky Phuong , Nguyen Duy Phuc Thanh , Chau Quyen Ngoc Do , Tran Tuan Du , Goh Xu Yang , Nguyen Son Truong
Published: September 2023

Recently, extensive research has been conducted on composite aerogel materials fabricated using industrial waste sources. These aerogels can not only help solve the most challenging environmental issues brought on by waste streams, but are also materials with excellent properties for thermal and acoustic insulation applications. This study, therefore, focuses on synthesizing composite aerogel using waste tire rubber powder and fly ash attained from power plants in a simple and environmentally friendly manner. The results show that the composite aerogel has a very low density (0.055- 0.079 g/cm3), a porosity of up to 96.57%, low thermal conductivity (0.022-0.039 W/m.K), an adequate noise reduction number (NRC) (0.41 at 250-4000 Hz) and high compressive Young’s modulus (120.5 kPa). These properties show the high potential of the material for thermal and sound insulation of buildings. Especially in the context of utilizing a reasonably priced source of waste material.