bluuebunny/crossref_metadata_2025 huggingface dataset:
Proposed structural and functional evaluation of unpaved roads improved with geosynthetics, reclaimed asphalt pavement and Portland cement
Authors: Albuquerque Filho Luiz Heleno , Dal Toé Casagrande Michéle , Martins Ribeiro Lu Fernandoís
Published: July 2024

The cargo transport network in Brazil is highly unbalanced, with a marked concentration of road transport in relation to other modes of transport. As if the flagrant imbalance between modes were not enough, serious distortions are also observed in the distribution of road network coverage. Only 13% of the Brazilian network has coating considered definitive, reinforcing the importance of unpaved roads in the transport network. Despite advances, the design methods for unpaved roads were mostly developed for roads treated with gravel in regions with a temperate climate, which are inconsistent with the nature and behavior of Brazilian tropical soils. They also disregard important soil improvement techniques, such as reinforcement with geosynthetics, incorporating civil construction waste, reclaimed asphalt pavement, mining tailings or chemical stabilization with different additives (hydrated lime, Portland cement, latex polymers, organic additives and asphalt emulsion). Faced with this challenging scenario, this research was designed to monitor the structural and functional conditions of unpaved road test sections in Brazil built with different soil reinforcement and stabilization techniques. The structural condition of the test sections will be evaluated through deflection measurements with the Light Weight Deflectometer (LWD), Benkelman beam, and Falling Weight Deflectometer (FWD), and the functional condition will be evaluated through field inspections for the qualification and quantification of defects. This article aims to present the synthesis of the proposed methodology and the initial results of soil characterization obtained in constructing the first test section located in an unpaved section of the Federal Highway BR-030, in the state of Bahia.
Impact of weathering on a cement-treated sand
Authors: Wassermann Alice , Abdallah Adel , Cuisinier Olivier
Published: July 2024

This study’s main goal was to examine how the wetting/drying solicitations affect the mechanical behavior of a cementtreated sand. A quantitative method based on the stress-dilatancy approach was used to assess the effects of two types of wetting and drying cycles of different intensities. The results showed that bonding is primarily altered by the wetting/drying cycles, leading to lower mechanical performances. It has been demonstrated that the weathering effect not only depends on the cement dosage, but also on the cycles’ intensity. The early cycles appeared to have the greatest impact on changes in mechanical performance on the samples treated with 4% cement. However, the accumulation of numerous cycles caused a more progressive degradation on the samples treated with 1% cement. The quantitative assessment of the treatment effect and the weathering progress with cycles was made possible through the evaluation of the bonding ratio. The importance of the imposed wetting/drying cycle protocol for a proper evaluation of the long-term performance of treated soils is highlighted. Further research is needed to define an appropriate weathering protocol that makes sense in light of the real solicitation faced by engineered structures.
Towards a monitoring tool to quantify urease during biocementation treatment at microscale
Authors: Borges Inês , Albuquerque Débora C. , Cardoso Susana , Cardoso Rafaela
Published: July 2024

Biocementation consists in using urease enzyme and a solution rich in urea and in calcium to precipitate calcium carbonate (biocement). When applying this treatment in soils, the biocement minerals bond the grains improving overall soil’s hydro-mechanical properties. For the practical use of this technique, it is necessary to be able to predict the properties of the treated soil after following specific protocols, by preference avoiding non-destructive testing such as those performed on samples extracted after the treatment. The amount of biocement precipitated depends on the amount of urease enzyme, urea and calcium. This idea has inspired the development of one magnetoresistive biosensor to detect urease, to be used as a non-destructive monitoring tool during the treatment. A magnetoresistive platform was used to quantify the signal, which is related to the urease concentration through a calibration curve. The sensor was tested to measure the enzyme present in the inflow and outflow fluids used to treat cylindrical soil samples (2.5 cm diameter and 2.0 cm height), prepared with a uniform grading size sand (D50=0.3 mm). Purified urease from Canavalia ensiformis, was used. The improvement of the biocemented sand samples was quantified through measuring the calcium carbonate content of the soil after the treatment and the values were related with the amount of enzyme retained by the soil, determined using the sensor readings. This work found, for the first time, the relationship between the measured concentration of urease retained by soil and the calcium carbonate content precipitated. This relationship is an important tool for monitoring the treatment, without the need to use destructive tests or even stop the treatment.
Thermo-hydro-mechanical behaviour of deep Ypresian clays
Authors: Sau Núria , Romero Enrique , Van Baelen Hervé
Published: July 2024

Investigating the thermo-hydro-mechanical behaviour of deep Ypresian clays (300 to 400 m below ground) is crucial since they are one of Belgium’s potential host rock formations for deep geological disposal of radioactive waste. To this aim, a newly designed and fully instrumented thermal oedometer cell with lateral stress measurement was used to determine the stress state accurately. First, well-preserved core samples were loaded to bring them to the large in situ stresses and reduce the induced matric suction on deep water-undrained sampling. The remaining matric suction was then reduced by soaking with synthetic water of the formation. Next, drained loading and unloading paths were followed to attain different vertical effective stresses at varying overconsolidation ratios (OCRs) before the drained thermal paths (heating and cooling). The results indicated a systematic increase in the horizontal effective stress on heating at constant vertical effective stress. In addition, thermal-induced volume changes in heating/cooling at different OCRs were studied. Test results were finally interpreted within a thermo-mechanical elastoplastic framework.
Non-isothermal kinetics and thermodynamics analysis of vanadium-titanium magnetite
Authors: Liu Ran , Liu Yanting , Gao Yanjia , Yan Guangshi , Lan Chenchen , Lv Qing
Published: July 2024

Thermodynamic calculations and thermal analysis tests were performed to investigate the thermodynamic and kinetic behaviors of the carbothermal reduction of vanadium-titanium magnetite w(C)/w(O) and basicity on the carbothermal reduction process of vanadium-titanium magnetite based on the HIsmelt process. Thermodynamic analysis showed that the addition of basicity promoted the reduction of vanadium-titanium magnetite, and the reaction onset temperature gradually increased with the decrease of the valence states of the elements V, Ti and Fe in the product. Increasing the amount of carbon assigned to the system gradually increased the mass fractions of metal Fe and Fe3C and raised the mass fractions of Ti, V and their low valence compounds at equilibrium. Increasing the basicity had less effect on the Fe, V and Ti fractions of the equilibrium system. The results of kinetic tests showed that the maximum reduction degree and maximum reaction rate of the reduction reaction by increasing w(C)/w(O) and basicity increased, the apparent activation energy and the finger front factor decreased, and the reaction mechanism function of the non-isothermal kinetic reduction process was f(α) = (3/2)(1−α)4/3[(1−α)−1/3−1]−1belonging to the three-dimensional Z-L-T diffusion model.
RiskTree: Decision trees for asset and process risk assessment quantification in big data platforms
Authors: Zhan Haomou , Yang Jiawei , Guo Zhenyang , Cao Jin , Zhang Dong , Zhao Xingwen , You Wei , Li Hui
Published: July 2024

Currently, big data platforms are widely applied across various industries. These platforms are characterized by large scale, diverse forms, high update frequency, and rapid data flow, making it challenging to directly apply existing risk quantification methods to them. Additionally, the composition of big data platforms varies among enterprises due to factors such as industry, economic capability, and technical proficiency. To address this, we first developed a risk quantification assessment process tailored to different types of big data platforms, taking into account relevant laws, regulations, and standards. Subsequently, we developed RiskTree, a risk quantification system for big data platforms, which supports automated detection of configuration files, traffic, and vulnerabilities. For situations where automated detection is not feasible or permitted, we provide a customized questionnaire system to collect assets and data processing procedures. We utilize a knowledge graph (KG) to integrate and analyze the collected data. Finally, we apply a random forest algorithm to compute risk index weights, risk values, and risk levels, enabling the quantification of risks on big data platforms. To validate the proposed process, we conducted experiments on an educational big data platform. The results demonstrate that the risk index system presented in this paper objectively and comprehensively reflects the risks faced by big data platforms. Furthermore, the proposed risk assessment process not only effectively identifies and quantifies risks but also provides highly interpretable evaluation results.
Long-term relationships of ionospheric electron density with solar activity
Authors: Jakowski Norbert , Hoque Mohammed Mainul , Mielich Jens
Published: July 2024

Greenhouse gases such as carbon dioxide and methane that are causing climate change may cause long-term trends in the thermosphere and ionosphere. The paper aims to contribute to exploring long-term effects in the ionosphere focusing on the impact of solar activity changes. Peak electron density data derived from vertical sounding measurements covering 65 years at the ionosonde stations Juliusruh (JR055), Boulder (BC840), and Kokubunji (TO536), have been utilized to estimate the long-term behavior of daytime ionospheric F2 layer ionization in relation to the solar 10.7 cm radio flux index F10.7. In parallel, Global Navigation Satellite System (GNSS) based vertical total electron content (TEC) data over the ionosonde stations in combination with the peak electron density data have been used to derive the equivalent slab thickness τ for estimating long-term behavior in the period 1996–2022. A new approach has been developed for deriving production and loss term proxies for studying long-term ionization effects from F2 layer peak electron density and TEC data. The derived coefficients allow for estimating the long-term variation of atomic oxygen and molecular nitrogen concentrations including their ratio during winter months. The noon-time slab thickness values over Juliusruh correlate well with the decrease of F10.7 and the F2 layer peak height and enable estimating the neutral gas temperature. The equivalent slab thickness decreases by about 20 km per decade in the period 1996–2022, indicating a thermospheric cooling of about 100 K per decade for Juliusruh. Whereas the oxygen concentration decreases, the loss term, considered as a proxy for molecular components of the neutral gas, in particular N2, increases with the long-term solar activity variation. Considering 11-year averages of the production and loss terms under wintertime conditions, the long-term study reveals for the O/N2 ratio a percentage decrease of 5% per decade and for F10.7 about 3.1% per decade in a linear approach referred to the year 1970. Linear models of 11 years averaged NmF2 and foF2 from corresponding F10.7 show a very close correlation with the temporal variation of F10.7 until about 1990. The root mean square errors are in the order of 1.0–1.3 · 1010 m−3 for NmF2 and 0.03–0.05 MHz for foF2. After 1990 the linear models deviate from F10.7 at all selected mid-latitude ionosonde stations indicating a non-local effect.
The Clinical Research on Ginger (Zingiber officinale): Insights from ClinicalTrials.gov analysis
Authors: Matin Maima , Matin Farhan Bin , Ksepka Natalia , Wysocki Kamil , Mickael Michel-Edwar , Wieczorek Marek , Horbańczuk Jarosław Olav , Jóźwik Artur , Atanasov Atanas G.
Published: June 2024

Ginger (Zingiber officinale) has a rich history of traditional medicinal use and has attracted a global interest in its health benefits. This study aims to provide insights into the clinical research landscape on ginger, focusing on its pharmacological effects and studied health-related outcomes. The study design involves systematic analysis of data from clinical trials available on ClinicalTrials.gov and discussion of findings in the context of the existing scientific knowledge. A comprehensive analysis of clinical trials registered on ClinicalTrials.gov related to ginger was first conducted, and the scientific background related to specific ginger clinical research avenues was further evaluated through PubMed searches. A variety of trial designs were identified, including treatment, prevention, and supportive care objectives. A total of 188 studies were identified on ClinicalTrials.gov, of which 89 met the inclusion criteria. Among the 89 trials, treatment
objectives were predominant (47.2%), and dietary supplements (40.4%) and drugs (27%) were the most prevalent intervention types. These trials covered various health outcomes, such as antiemetic activity, analgesic function, effects on health-related quality of life, blood pressure variation, energy expenditure, and reduction in xerostomia. This study analysis provides a comprehensive overview of the clinical trials landscape on ginger, focusing on its broad spectrum of potential health benefits. While individual trials show promising results, a significant gap in the available data with a low reporting rate of final results is identified, underscoring the need for further research to establish conclusive evidence of gingerʼs therapeutic potentials.
Homoeopathy for the Management of Delusional Disorder: A Case Report
Authors: Moorthi S. Karunakara , K.C Manu Chandran
Published: July 2024

Introduction Delusions, a core symptom of psychosis, are false beliefs that are rigidly held with strong conviction despite contradictory evidence. Persistent delusions if held for more than 1 month lead to the diagnosis of delusional disorder (DD) as per the Diagnostic and Statistical Manual of Mental Disorders-5. Very sparse literature is available evaluating the utility of individualised homoeopathic medicine in this condition.

Materials and Methods A 60-year-old man presenting with symptoms of DD was treated during the period of February 2020 to February 2021. Individualised homoeopathic medicine was prescribed. Outcomes were assessed using Psychotic Symptom Rating Scales. Modified Naranjo Criteria was used to assess whether the changes were likely to be associated with the homoeopathic intervention.

Results A beneficial result was obtained from Individualised homoeopathic treatment.

Conclusion Even though this is a single case report, the recovery of the patient from the suspiciousness is remarkable and there is no relapse of the symptoms. The patient's family life is peaceful now and he was able to rejoin his job.
Medium- and long-term outcomes of early childhood education: experiences from Turkish large-scale assessments
Authors: Suna H. Eren , Ozer Mahmut
Published: June 2024

The benefits of early childhood education (ECE) to children extend throughout their lives. A more equitable education system is also dependent upon the universalization of ECE, beyond its personal benefits. A limited number of studies have examined the relationship between ECE attendance and educational outcomes in Türkiye, despite its importance at both the educational and systemic levels. As part of this comparative study, we examined the relationship between ECE attendance and academic achievement in Türkiye over the medium and long term. We considered high stakes assessments for the transition to upper-secondary education (at the end of the eighth grade) and higher education (at the end of the 12th grade) within the scope of this study. Based on the official student recordings in Türkiye, ~5.6 million students were analyzed in the study. For the comparison of group means, partial-eta squares were used, and descriptive comparisons were made for the comparison of group rates. There was a stronger relationship between ECE attendance and medium-term achievement. As a result, students who attended an ECE program had significantly higher scores on the transition to upper-secondary education. Despite similar rates of transition, attendance had a higher rate of transition to formal bachelor programs, prestigious higher education programs, and students’ prioritized programs. ECE programs are particularly beneficial to students with low socio-economic status (SES) according to additional analyses. Medium- and long-term academic indicators are correlated with ECE attendance, with the medium-term relationship being particularly robust. This emphasizes the importance of recent investments in universalizing early childhood education in Türkiye. It is suggested that further research be conducted in order to control SES and other demographic variables.
Building an AI ecosystem in a small nation: lessons from Singapore’s journey to the forefront of AI
Authors: Khanal Shaleen , Zhang Hongzhou , Taeihagh Araz
Published: July 2024

Artificial intelligence (AI) is arguably the most transformative technology of our time. While all nations would like to mobilize their resources to play an active role in AI development and utilization, only a few nations, such as the United States and China, have the resources and capacity to do so. If so, how can smaller or less resourceful countries navigate the technological terrain to emerge at the forefront of AI development? This research presents an in-depth analysis of Singapore’s journey in constructing a robust AI ecosystem amidst the prevailing global dominance of the United States and China. By examining the case of Singapore, we argue that by designing policies that address risks associated with AI development and implementation, smaller countries can create a vibrant AI ecosystem that encourages experimentation and early adoption of the technology. In addition, through Singapore’s case, we demonstrate the active role the government can play, not only as a policymaker but also as a steward to guide the rest of the economy towards the application of AI.
Herglotz-type vakonomic dynamics and its Noether symmetry for nonholonomic constrained systems
Authors: Huang Li-Qin , Zhang Yi
Published: July 2024

In this paper, Herglotz-type vakonomic dynamics and Noether theory of nonholonomic systems are studied. Firstly, Herglotz-type vakonomic dynamical equations for nonholonomic systems are derived on the premise of Herglotz variational principle. Secondly, in terms of the Herglotz-type vakonomic dynamical equations, the Noether symmetry of Herglotz-type vakonomic dynamics is explored, and the Herglotz-type vakonomic dynamical Noether theorems and their inverse theorems are deduced. Finally, the conservation laws of Appell–Hamel case with non-conservative forces are analyzed to show the validity of our results.
Harnessing ion beam erosion engineering for controlled self-assembly and tunable magnetic anisotropy in epitaxial films
Authors: Bera Anup Kumar , Jamal Md. Shahid , Khanderao Avinash Ganesh , Singh Sharanjeet , Kumar Dileep
Published: July 2024

The engineering of the surface morphology and the structure of the thin film is one of the essential technological assets for regulating the physical properties and functionalities of thin film-based devices. This study presents an easy and handy approach to tailor the surface structure of epitaxial thin films utilizing low-energy ion beam. Here, we investigate the evolution of the surface structure and magnetic anisotropy (MA) in epitaxial Fe/MgO (001) model systems subjected to multiple cycles of ion beam erosion (IBE) after thin film growth. The growth of Fe film occurs in the form of three–dimensional islands and exhibits intrinsic biaxial MA. Following a few cycles of IBE, an induced uniaxial magnetic anisotropy leads to a split in the hysteresis loop, and the film displays almost uniaxial magnetic switching behavior. More distinctly, we present a clear and conclusive evidence of (2 × 2) reconstruction of the Fe surface due to the atomic rearrangement by IBE. Furthermore, 57Fe isotope sensitive nuclear resonance scattering measurement provides insight into the depth-resolved magnetic information due to the modified surface topography. We also demonstrate that thermal annealing can reversibly tune the surface reconstruction and induced UMA. The feasibility of the IBE technique by adequately selecting IBE parameters for surface structure modification has been highlighted apart from conventional tailoring of the morphology for the tuning of UMA and introduces a new dimension to our understanding of self-assembled surface morphology evolution by IBE.
Ion induced nucleation of charged droplets enhanced by external electric field
Authors: Yang Yong , Chen Huan , Li Chuan , Wang Pengyu
Published: July 2024

The nucleation theory of charged particles in an external electric field environment is considered. The Gibbs free energy and nucleation rate changes of ion-induced nucleation under an external electric field are studied. The Classical Kelvin–Thomson equation and the ion-induced nucleation theory in the external electric field environment are corrected. The results show that the presence of an electric field can reduce the Gibbs free energy of nucleation and increase the nucleation rate. For particles larger than a few nanometers in size, the impact of the external electric field on reducing the condensation saturation ratio is more pronounced than the combined influence of the Thomson effect and dipole–charge interaction.
A novel means to generate high pressure
Authors: Pravica Michael , Cifligu Petrika , Sanchez Adrian Lua , Malik Trimaan , Appathurai Narayan , Moreno Beatriz Diaz
Published: July 2024

Diamond anvil cells are the most popular means of generating pressures above 2 GPa. However, in many experiments, such as nuclear magnetic resonance and x-ray absorption, the metallic pressurizing gasket (which confines much of the sample) represents an occluding barrier that requires a low Z gasket material (e.g., Be), a split gasket, or other means to enable better coupling of the sample to electromagnetic radiation. In this paper, we demonstrate a novel method for generating high pressures that confines the sample just above the plane of the gasket by using a diamond with a laser hole drilled into the center of the tip. The sample is then confined by the hole, which is sealed by a flat gasket that fits over the hole. When load is applied to the diamonds, metal flows from the deformed gasket into the hole thereby pressurizing the sample similarly to how a piston pressurizes gas inside a cylinder. The pressurized sample is above the metallic gasket plane just inside the tip of the diamond, and thus easily accessible via x rays or visible light that skims just above the plane of the gasket providing an enhanced aperture of radiation collection. We have demonstrated the utility of this method by obtaining Raman spectra of SnC2O4 and x-ray diffraction spectra of seleno-DL-cystine, all at high pressures.
Low-frequency noise attenuation through hybrid perforated hemispherical shells and membrane-type acoustic metamaterial
Authors: Katiyar Nitish , Choudhury Sagnik Sarma , Kant Rishi , Bhattacharya Shantanu
Published: July 2024

We propose a novel hybrid acoustic metamaterial that can achieve broadband sound insulation below 452 Hz and almost perfect sound absorption at 864 Hz. The metastructure was fabricated using additive manufacturing. Finite element method simulations were used to study the acoustic properties of the fabricated metamaterials. An equivalent electrical circuit was built using an electro-acoustic analogy to evaluate the sound absorption coefficient. The unique design of this meta-structure possesses two resonant frequencies. Low-frequency sound insulation is found due to the effective negative density at frequencies lower than the cutoff frequency of the elastic membrane. In contrast, a negative effective bulk modulus is the reason behind the broadband sound absorption. The theoretical and simulation results were validated through experiments. Experiments carried out showed an overall average sound transmission loss of 26.31 dB between 50 and 1600 Hz and 24.72 dB in the low-frequency zone (<400 Hz). Furthermore, over 69% of the sound intensity is absorbed in the 500–1000 Hz frequency range. The designed meta-structure exhibits broadband effective negative density below 452 Hz and effective negative bulk modulus from 864 to 1220 Hz. The design specifies a sample thickness of 3.8 cm, corresponding to a subwavelength thickness of approximately λ/10. As a result, the developed meta-structure can potentially be employed for sound insulation and absorption at low frequencies in the aerospace and automotive industries and in-room acoustic applications.
X-ray tomography system concept for stellarator TJ-II
Authors: Jabłoński Sławomir , Chernyshova Maryna , Malinowski Karol , McCarthy Kieran
Published: July 2024

A method based on the principle of x-ray tomography is a good way of assessing the parameters of the radiation emission distribution in the plasma. In this method, a set of radiation detectors is usually placed around a selected section of the plasma or in two groups of detectors arranged perpendicularly to each other in the top and side positions. Such an arrangement is intended to provide a sufficient amount of data to reconstruct the distribution of radiation emission intensities across the plasma cross section. For the plasma produced in the TJ-II stellarator, a two-dimensional (2D) imaging detector is proposed with the ability to discriminate photon energy in only one specifically selected position in the toroidal direction. The proposed diagnostics could come with advantages of a 2D toroidal camera, providing access to 3D information, and would complement standard poloidal tomography. It could be used either for better constraining of the 2D tomography in simple cases with axisymmetric SXR emissivity, for simulation validation of 3D effects in a synthetic diagnostic approach, or to attempt direct 3D tomography. The subject of this contribution is to present the idea of a 3D x-ray tomography system based on the use of a square matrix of GEM detector and the obtained preliminary results of the conducted simulations. The developed diagnostics is to contain 33 462 detection pixels associated with lines of sight. The analysis was carried out on the basis of the numerical simulations based on the GEM_MP.exe and Tomography.exe computer codes (both created at IPPLM) enabling the consideration of free-free, free-bound, and bound-bound x-ray radiation reaching each of the pixels of the GEM diagnostics (GEM_MP.exe code) and testing algorithms proposed for tomographic reconstruction of the plasma emissivity (Tomography.exe code). During calculations, real profiles of electron density and electron temperature, as well as real geometry of the measuring system were taken into account. Additionally, the influence of factors such as filters used in the detector and the efficiency of the used active medium on the quality of tomographic reconstruction was examined. The summary evaluates the proposed tomographic reconstruction method.
Highly functional duodenal stent with photosensitizers enables photodynamic therapy for metabolic syndrome treatment: Feasibility and safety study in a porcine model
Authors: Park Chan Su , Park Hyun Jin , Park Ji Hoon , Lee Jin Hee , Kee Hyun Jung , Park Jung-Hoon , Jo Jung Hyun , Lee Hee Seung , Ku Cheol Ryong , Park Jeong Youp , Bang Seungmin , Song Jung Min , Na Kun , Kang Sung Kwon , Jung Hwoon-Yong , Chung Moon Jae
Published: July 2024

Duodenal mucosal resurfacing (DMR) by thermal ablation of the duodenal mucosa is a minimally invasive endoscopic procedure for controlling metabolic syndrome (MS). However, thermal energy can cause adverse effects due to deep mucosal injury, necessitating an additional mucosal lifting process, which complicate the procedures. Therefore, we aimed to develop a similar procedure using non-thermal photodynamic therapy (PDT) for DMR using a highly functional metal stent covered with photosensitizers (PSs) to minimize the potential risks of thermal ablation injury. We developed a novel PS stent enabling the controlled release of radical oxygen species with specific structures to prevent stent migration and duodenal stricture after ablation and performed an animal study (n = 8) to demonstrate the feasibility and safety of PDT for DMR. The stents were placed for 7 days to prevent duodenal strictures after PDT. To confirm PDT efficacy, we stained for gastric inhibitory polypeptide (GIP) and glucose transporter isoform 1. The PS stents were deployed, and PDT was applied without evidence of duodenal stricture, pancreatitis, or hemorrhage in any of the pigs. Microscopic evaluation indicated apoptosis of the mucosal cells in the irradiated duodenum on days 7 and 14, which recovered after day 28. Immunohistochemistry revealed suppressed GIP expression in the mucosal wall of the irradiated duodenum. Endoscopic PDT for DMR using PS stents could be applied safely in a porcine model and may result in decreased GIP secretion, which is a crucial mechanism in MS treatment. Further clinical studies are required to explore its safety and efficacy in patients with MS.
Elastic moduli from crystalline micro-mechanical oscillators carved by focused ion beam
Authors: Estry Amelia , Putzke Carsten , Guo Chunyu , Bachmann Maja , Duvakina Anna , Posva Ferdinand , Diaz Jonas , Gawryluk Dariusz J. , Medarde Marisa , Moll Philip
Published: July 2024

The elastic moduli provide unique insights into the thermodynamics of quantum materials, particularly into the symmetries broken at their phase transition. Here, we present a workflow to carve crystalline resonators via focused ion beam milling from small and oddly shaped crystals unsuitable for traditional measurements of elasticity. The accuracy of this technique is first established in silicon. Next, we showcase the capacity to probe changes in the electronic state with a resolution on the measured resonance frequency as small as 0.01% on YNiO3, a rare-earth perovskite nickelate, in which bulk single crystals have typical length scales of ≈40μm. Here, we observe a sharp 0.2% discontinuity in Young’s modulus of an YNiO3 cantilever at a magnetic phase transition. Finally, an additional potential of using free-standing cantilevers as a tool for examining the time-dependence of chemical changes is illustrated by laser-heating YNiO3.
Turbulent flow over aligned cylindrical obstacles
Authors: Duan G. , Gao R. , Zhao L. , Yang T. , Ngan K.
Published: July 2024

Turbulent flow and boundary-layer (BL) characteristics over cylindrical obstacles have been understudied compared to the flow dynamics around cubic roughness in the urban BL literature. Using large-eddy simulation, we investigate a turbulent BL flow developed over two vertically oriented cylindrical obstacles aligned downstream. For widely separated cylinders, the wake flow undergoes periodic oscillations akin to vortex shedding behind an isolated cylinder. As the height-to-width aspect ratio (AR) of the canyon bounded by the cylinders increases, the streamline geometry exhibits a clear transition from isolated to wake interference and skimming regimes. Two-point autocorrelation functions of velocities confirm a strong coupling of canyon flow with the roughness sublayer for wider canyons, while with evident decoupling as the canyon narrows. The length scales, which measure the spatial correlation in the flow, decrease in both lateral and vertical directions with increasing AR. Turbulent kinetic energy and momentum fluxes below the roughness sublayer present pronounced monotonic scaling with AR (with R-squared values up to 0.84 and 0.98, respectively), resulting in a consistent variation in the surface roughness aerodynamic parameters, the roughness length (z0) and zero-plane displacement (d), with AR. Quantitative differences in the results with respect to those well-established for street canyons are analyzed, with the similarities highlighted. The results offer insights into boundary-layer flow parameterization concerning cylinder-occupied surface roughness.
An experimental study of fluid–structure interaction and self-excited oscillation in thin-walled collapsible tube
Authors: Chowdhury Sifat Karim , Zhang Yan
Published: July 2024

Flow through thin-walled collapsible tubes often exhibits a complex nonlinear interplay between fluid dynamics and structural mechanics. This paper presents findings from an experimental investigation employing quantitative analyses of structural deformation and flow fields through image analysis and particle image velocimetry (PIV) measurements. The results suggest that as Reynolds number (Re) increases, the tube experiences buckling and collapses under greater negative transmural pressures (Ptm) compared with no flow condition, indicating that increasing flow inertia delays the onset of collapse. The onset of self-excited oscillation is marked by a Re threshold. Beyond this threshold, self-excited oscillations occur within a specific range of Ptm. Small-amplitude, chaotic oscillations emerge at relatively low Re or when Ptm approaches the upper limit of the oscillation-inducing regime. Conversely, large-amplitude, periodic oscillations arise as Re increases and Ptm decreases. The frequency of oscillation escalates with increasing Re and decreasing Ptm, while amplitude peaks near the midpoint of the oscillation-inducing Ptm range. PIV results indicate that large-amplitude, periodic oscillations correlate with asymmetric jet flows that switch directions from cycle to cycle. Furthermore, self-excited oscillations reduce overall flow resistance, thereby mitigating flow limitations under highly negative Ptm. These findings contribute to a deeper understanding of collapsible tube dynamics under varying flow conditions, with implications for diverse fields ranging from biomedical engineering to space physiology.
Research on the effects of volute area ratios on centrifugal pump internal flow and noise
Authors: Jia XiaoQi , Li YuPeng , Zhang Jun , Yan ChaoShou , Lin Zhe , Zhu ZuChao
Published: July 2024

Centrifugal pumps, which are essential for the transfer of fluids, are extensively utilized in industries like aerospace and new energy vehicles. These fields require pumps to meet rigorous standards in terms of reliability, efficiency, and vibrational noise while also imposing stringent restrictions on their size and weight. Therefore, achieving optimal performance in terms of both efficiency and noise reduction for centrifugal pumps in limited space poses a considerable difficulty. This study investigates the impact of different volute area ratios on the internal flow properties and noise levels of centrifugal pumps, using area ratio theory as a foundation. Both experimental and computational simulations are used, with the pump dimensions kept constant. The results demonstrate that an augmentation in the volute area ratio greatly improves the pump's exterior properties, notably decreases internal vorticity, and boosts flow conditions. The pressure fluctuations in the pumps show an overall decrease, accompanied by changes in their distribution patterns. In addition, the sound pressure levels in the exterior sound field of the pumps typically decrease, accompanied by obvious changes in directivity. The sound pressure levels within the internal sound field are significantly reduced, especially in areas of the volute wall that were previously known for having high sound pressure. By analyzing the relationship between sound pressure and pressure pulsation on the wall surface of the volute, as well as the impact of area ratio on pressure pulsation distribution in the sound field of the centrifugal pump, it is evident that the theory of area ratio can be utilized to effectively decrease pressure pulsation in the centrifugal pump, thereby reducing the noise generated by the pump.
Cross-correlated relaxation in the NMR of near-equivalent spin pairs: Longitudinal relaxation and long-lived singlet order
Authors: Whipham James W. , Sabba Mohamed , Dagys Laurynas , Moustafa Gamal , Bengs Christian , Levitt Malcolm H.
Published: July 2024

The evolution of nuclear spin state populations is investigated for the case of a 13C2-labeled triyne in solution, for which the near-equivalent coupled pairs of 13C nuclei experience cross-correlated relaxation mechanisms. Inversion-recovery experiments reveal different recovery curves for the main peak amplitudes, especially when the conversion of population imbalances to observable coherences is induced by a radio frequency pulse with a small flip angle. Measurements are performed over a range of magnetic fields by using a sample shuttle apparatus. In some cases, the time constant TS for decay of nuclear singlet order is more than 100 times larger than the time constant T1 for the equilibration of longitudinal magnetization. The results are interpreted by a theoretical model incorporating cross-correlated relaxation mechanisms, anisotropic rotational diffusion, and an external random magnetic field. A Lindbladian formalism is used to describe the dissipative dynamics of the spin system in an environment of finite temperature. Good agreement is achieved between theory and experiment.
Self-adaptive and time divide-and-conquer physics-informed neural networks for two-phase flow simulations using interface tracking methods
Authors: Zhou Wen , Miwa Shuichiro , Okamoto Koji
Published: July 2024

Physics-informed neural networks (PINNs) are emerging as a promising artificial intelligence approach for solving complex two-phase flow simulations. A critical challenge in these simulations is an accurate representation of the gas–liquid interface using interface tracking methods. While numerous studies in conventional computational fluid dynamics (CFD) have addressed this issue, there remains a notable absence of research within the context of PINNs-based two-phase flow simulations. Therefore, this study aims to develop a robust and generic PINNs for two-phase flow by incorporating the governing equations with three advanced interface tracking methods—specifically, the Volume of Fluid, Level Set, and Phase-Field method—into an improved PINN framework that has been previously proposed and validated. To further enhance the performance of the PINNs in simulating two-phase flow, the phase field constraints, residual connection and the time divide-and-conquer strategies are employed for restricting neural network training within the scope of physical laws. This self-adaptive and time divide-and-conquer (AT) PINNs is then optimized by minimizing both the residual and loss terms of partial differential equation. By incorporating the three different interface tracking methods, it efficiently handles high-order derivative terms and captures the phase interface. The case of single rising bubble in two-phase flow is simulated to validate the robustness and accuracy of the AT PINNs. The simulation's accuracy is evaluated by comparing its performance in terms of velocity, pressure, phase field, center of mass, and rising velocity with that of conventional PINNs and CFD benchmarks. The results indicate that the AT PINNs coupled with these interface tracking methods offers a satisfactory performance in simulating rising bubble phenomenon.
The composited high reflectivity p-type electrodes with patterned ITO for AlGaN-based ultraviolet light emitting diodes
Authors: Lang J. , Xu F. J. , Wang J. M. , Zhang L. S. , Sun Z. H. , Zhang H. D. , Guo X. Q. , Zhang Z. Y. , Ji C. , Tan F. Y. , Ji C. Z. , Kang X. N. , Yang X. L. , Tang N. , Chen Z. Z. , Wang X. Q. , Ge W. K. , Shen B.
Published: July 2024

Composited p-type electrodes with high reflectivity have been investigated in AlGaN-based ultraviolet light emitting diodes (UV-LEDs) to improve the light extraction efficiency, which are composed of a patterned ITO layer and an Al reflector. It is verified that the patterned ITO with a thickness of 30 nm can not only well form Ohmic contact with p-GaN capping layer, but also be nearly 90% transparent to ultraviolet light, and thus presenting a reflectivity of 73% at 280 nm when combined with an Al reflector. Further experimental efforts confirm that the performance of the UV-LEDs is dramatically improved with such p-type electrodes. The maximum light output power and wall plug efficiency in the current range of 0–100 mA are severally increased by 49.8% and 54.2% compared to the device with traditional Ni/Au electrodes.
Large eddy simulation and linear stability analysis of active sway control for wind turbine array wake
Authors: Li Zhaobin , Li Yunliang , Yang Xiaolei
Published: July 2024

The convective instability of wind turbine wakes allows specific upstream forcing to amplify downstream, leading to increased wake meandering and replenishment, thereby providing a theoretical basis for active wake control. In this study, the active sway control—a strategy previously proven to enhance wake recovery at the single wind turbine level—is analyzed at the turbine array level. The similarity and differences between individual turbine wakes and the wake array are analyzed using large eddy simulations and linear stability analysis, considering both uniform and turbulent inflow conditions. For cases with uniform inflow, large eddy simulations reveal significant meandering motion in the wake array induced by active sway control at a motion amplitude of 1% rotor diameter, consistent with previous studies of standalone wind turbine wakes. Nevertheless, the sensitive frequency for the wake array extends down to St = 0.125 below the limit of St > 0.2 for a single wake, and the optimal control frequency for the standalone turbine wake becomes suboptimal for the array. Linear stability analysis reveals the underlying mechanism of this frequency shift as changes in the shear-layer instability due to the overlap of upstream and downstream wakes and is capable to provide fast estimation of optimal control frequencies. When inflow turbulence intensity increases, the gain of active sway control is reduced, underscoring the importance of low-turbulence environment for successfully implementing the active sway control. The reduction in wake response is captured by the linear stability analysis if the base flow accounts for the faster wake expansion caused by inflow turbulence.
On the quantum dynamical treatment of surface vibrational modes for reactive scattering of H2 from Cu(111) at 925 K
Authors: Sah Mantu Kumar , Naskar Koushik , Adhikari Satrajit , Smits Bauke , Meyer Jörg , Somers Mark F.
Published: July 2024

We construct the effective Hartree potential for H2 on Cu(111) as introduced in our earlier work [Dutta et al., J. Chem. Phys. 154, 104103 (2021), and Dutta et al., J. Chem. Phys. 157, 194112 (2022)] starting from the same gas–metal interaction potential obtained for 0 K. Unlike in that work, we now explicitly account for surface expansion at 925 K and investigate different models to describe the surface vibrational modes: (i) a cluster model yielding harmonic normal modes at 0 K and (ii) slab models resulting in phonons at 0 and 925 K according to the quasi-harmonic approximation—all consistently calculated at the density functional theory level with the same exchange–correlation potential. While performing dynamical calculations for the H2(v = 0, j = 0)–Cu(111) system employing Hartree potential constructed with 925 K phonons and surface temperature, (i) the calculated chemisorption probabilities are the highest compared to the other approaches over the energy domain and (ii) the threshold for the reaction probability is the lowest, in close agreement with the experiment. Although the survival probabilities (v′ = 0) depict the expected trend (lower in magnitude), the excitation probabilities (v′ = 1) display a higher magnitude since the 925 K phonons and surface temperature are more effective for the excitation process compared to the phonons/normal modes obtained from the other approaches investigated to describe the surface.
Transfer of hexagonal boron nitride quantum emitters onto arbitrary substrates with zero thermal budget
Authors: O’Hara Dante J. , Chuang Hsun-Jen , McCreary Kathleen M. , Noyan Mehmet A. , Lee Sung-Joon , Cobas Enrique D. , Jonker Berend T.
Published: July 2024

The van der Waals material hexagonal boron nitride (hBN) has emerged as a promising candidate for hosting room temperature single-photon emitters (SPEs) for next-generation quantum technologies. However, the requirement of a high temperature anneal (850 °C or higher) to activate the SPEs in hBN makes it difficult to integrate into hybrid structures that cannot tolerate such temperatures, including all silicon-based circuits. In this work, we present a method to deterministically activate quantum emitters in multilayered hBN on a process substrate, followed by a zero thermal budget transfer to a target substrate. This technique does not lead to any degradation or loss of photon purity in the hBN emitters and provides a procedure for combining high-purity emitters with other exciting photonic, magnetic, or electrical properties to explore new physical phenomena. The ability to transfer hBN emitters onto arbitrary substrates creates new technological possibilities to incorporate these quantum photonic properties into photonic integrated circuits and plasmonic devices.
Relative decline in density of Northern Hemisphere tree species in warm and arid regions of their climate niches
Authors: Astigarraga Julen , Esquivel-Muelbert Adriane , Ruiz-Benito Paloma , Rodríguez-Sánchez Francisco , Zavala Miguel A. , Vilà-Cabrera Albert , Schelhaas Mart-Jan , Kunstler Georges , Woodall Christopher W. , Cienciala Emil , Dahlgren Jonas , Govaere Leen , König Louis A. , Lehtonen Aleksi , Talarczyk Andrzej , Liu Daijun , Pugh Thomas A. M.
Published: July 2024

Although climate change is expected to drive tree species toward colder and wetter regions of their distribution, broadscale empirical evidence is lacking. One possibility is that past and present human activities in forests obscure or alter the effects of climate. Here, using data from more than two million monitored trees from 73 widely distributed species, we quantify changes in tree species density within their climatic niches across Northern Hemisphere forests. We observe a reduction in mean density across species, coupled with a tendency toward increasing tree size. However, the direction and magnitude of changes in density exhibit considerable variability between species, influenced by stand development that results from previous stand-level disturbances. Remarkably, when accounting for stand development, our findings show a significant change in density toward cold and wet climatic conditions for 43% of the species, compared to only 14% of species significantly changing their density toward warm and arid conditions in both early- and late-development stands. The observed changes in climate-driven density showed no clear association with species traits related to drought tolerance, recruitment and dispersal capacity, or resource use, nor with the temperature or aridity affiliation of the species, leaving the underlying mechanism uncertain. Forest conservation policies and associated management strategies might want to consider anticipated long-term species range shifts alongside the integration of contemporary within-distribution density changes.