bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Stefan flow on the flow field and heat transfer near wall of supercritical carbon dioxide flowing over a stationary spherical particle
Authors: Jiang Kun , Zhao Qiuyang , Yu Haocheng , Shi Jinwen , Jin Hui
Published: February 2023

In industrial applications, the phenomenon of scCO2 (supercritical carbon dioxide) flowing over particles is quite common. Considering that the scCO2 is chemically inactive but has high solubility, the pure Stefan flow will present without the related diffusion of a chemical reaction component and reaction heat, during the process of a spherical particle in the solid phase dissolved in a system of scCO2. To this, particle resolve-direct numerical simulation without considering the role of gravity and buoyancy is employed in this paper to investigate the high-temperature scCO2 flowing over a low-temperature stationary sphere with the uniformly, normally, and outward distributed Stefan flow on its surface, with the above cases conducted in the process of small variations on physical properties of scCO2. We present a series of variables in the flow field and temperature field near the sphere surface to study the effects of Stefan flow on them compared with cases without Stefan flow. Related distribution details of the velocity boundary layer and the temperature boundary layer near the sphere surface under conditions with or without the Stefan flow are also presented and analyzed. Different from other similar studies, our study also pays more attention to variables of the local fluid field as well as temperature field near the surface of the spherical particle. The results show that the presence of Stefan flow will reduce flow resistance of the freestream but inhibits heat transfer performance. Simpler correlations in form compared with previous well-established correlations are presented and are used to describe the operating conditions proposed herein.
Investigation of flow control methods for reducing heat flux on a V-shaped blunt leading edge under real gas effects
Authors: Li Shuai , Yan Chao , Kang Dake , Liu Sijia , Jiang Zhenhua
Published: February 2023

Complex shock interactions and severe aerothermal loads are often encountered on the lips of three-dimensional inward-turning inlets, which presents significant challenges to the performance and safety of hypersonic flight vehicles. However, there have been few investigations on reducing the heat flux of the lips, especially when considering real gas effects. It is, therefore, necessary to investigate flow control methods that are suitable for the lips under real gas effects. Three flow control methods are implemented in this work—a passive method with the shock control bump and stagnation bulge, an active method with counterflow jet, and a combined method. The lip is simplified as a V-shaped blunt leading edge to eliminate the influence of other structures. Numerical simulations are performed at freestream Mach numbers ranging from 6.0 to 12.0. The principles and abilities of different flow control methods for reducing heat flux are compared and analyzed. Although the passive and active methods can reduce the heat flux by more than 40% at low Mach numbers, they have an apparent deficiency under strong real gas effects at high Mach numbers. Moreover, the active method causes new heat flux peaks near the nozzle and at the reattachment position of the flow separation zone. Therefore, a combined method is proposed for further reducing the heat flux. By coupling the passive and active methods, the combined method can reduce the heat flux by nearly 60%. In general, the flow control methods investigated in this work can achieve satisfactory heat flux reduction abilities.
Permeability prediction of considering organic matter distribution based on deep learning
Authors: Sun Hai , Zhou Liang , Fan Dongyan , Zhang Lei , Yang Yongfei , Zhang Kai , Yao Jun
Published: February 2023

At present, researchers predict permeability through core experiments that require specific experimental conditions and methods, which are difficult and time-consuming. Conventional simulation methods for predicting permeability require considerable computational resources. Therefore, deep learning can be used as a pore-scale simulation prediction method. In this study, we established a workflow for directly predicting permeability from images. Considering that the mineral properties of the nanopore wall of shale oil have a large influence on the flow, a core dataset with organic distribution was constructed with random circles, and the slip influence of organic pores was considered. From our dataset, we found that the average permeability with organic distribution was 32.3% higher than that without organic distribution. Therefore, to simulate the microscopic flow and predict the permeability of shale oil, considering the differences in the pore flow mechanisms of different minerals is necessary. We designed a convolutional network for the dataset, adopted the structure of SE-ResNet, added the squeeze-and-excitation (SE) module to the double-layer residual module of ResNet18, and combined the characteristics of the SE block with the attention mechanism and ResNet to effectively obtain the information between channels and avoid the problem of gradient disappearance or explosion. Using SE-ResNet for directly predicting the apparent permeability from images, the accuracy of the test set reached 88.5%. The model had strong generalization ability, and the SE-ResNet could map the image of the core to the apparent permeability, which was approximately 100 times faster than the direct flow simulation.
Effect of cavity aspect ratio on mixed convective heat transfer phenomenon inside a lid-driven cavity due to elastic turbulence
Authors: Gupta S. , Sasmal C.
Published: February 2023

This study performs extensive numerical simulations to investigate how the aspect ratio (AR) of a lid-driven cavity influences the onset of elastic instability and elastic turbulence and the subsequent mixed convective heat transfer rate inside it. To this end, we utilize the finite volume method based open source code OpenFOAM along with Rheotool to solve the mass, momentum, energy, and viscoelastic constitutive equations. We find that the dependency of the cavity AR on the heat transfer rate is highly complicated depending upon the values of the Richardson (Ri) and Prandtl numbers (Pr). At low values of Ri, the heat transfer rate continuously decreases with AR irrespective of the value of the Prandtl number and the fluid type, i.e., Newtonian or viscoelastic. The same trend is also observed at high values of Ri and low values of Pr. At these combinations of Ri and Pr, the heat transfer rate is always higher in viscoelastic fluids than in Newtonian fluids due to the presence of elastic turbulence in the former fluids. However, a different trend is observed at high values of both Ri and Pr. At this combination of Ri and Pr, the heat transfer rate increases with AR in Newtonian fluids, whereas it decreases in viscoelastic fluids. Therefore, at high values of AR, Ri, and Pr, the heat transfer rate is higher in Newtonian fluids than that in viscoelastic fluids despite the presence of elastic turbulence in the latter fluids. This is in contrast to the assumption that the elastic turbulence phenomenon always increases the rate of transport processes. A possible explanation for this behavior is provided in this study. Along with the heat transfer aspects, we also provide a detailed discussion on how the cavity aspect ratio influences the corresponding flow dynamics inside the cavity. In particular, we find that the onset of the elastic instability (and the subsequent elastic turbulence) phenomenon is delayed to higher values of the Weissenberg number as the cavity aspect ratio increases. This is in line with prior experimental studies reported in the literature.
Reassessing the claimed cytokinin-substituting activity of dehydrodiconiferyl alcohol glucoside
Authors: Witvrouw Klaas , Kim Hoon , Vanholme Ruben , Goeminne Geert , Ralph John , Boerjan Wout , Vanholme Bartel
Published: February 2023

Dehydrodiconiferyl alcohol glucoside (DCG) is a phenylpropanoid-derived plant metabolite with reported cytokinin-substituting and cell-division-promoting activity. Despite its claimed activity, DCG did not trigger morphological changes in Arabidopsis seedlings nor did it alter transcriptional shifts in cell division and cytokinin-responsive genes. In reinvestigating the bioactivity of DCG in its original setting, the previously described stimulation of tobacco callus formation could not be confirmed. No evidence was found that DCG is actually taken up by plant cells, which could explain the absence of any observable activity in the performed experiments. The DCG content in plant tissue increased when feeding explants with the DCG aglycone dehydrodiconiferyl alcohol, which is readily taken up and converted to DCG by plant cells. Despite the increased DCG content, no activity for this metabolite could be demonstrated. Our results therefore demand a reevaluation of the often-quoted cytokinin-substituting and cell-division-promoting activity that has previously been attributed to this metabolite.
Reimagining the machine learning life cycle to improve educational outcomes of students
Authors: Liu Lydia T. , Wang Serena , Britton Tolani , Abebe Rediet
Published: February 2023

Machine learning (ML) techniques are increasingly prevalent in education, from their use in predicting student dropout to assisting in university admissions and facilitating the rise of massive open online courses (MOOCs). Given the rapid growth of these novel uses, there is a pressing need to investigate how ML techniques support long-standing education principles and goals. In this work, we shed light on this complex landscape drawing on qualitative insights from interviews with education experts. These interviews comprise in-depth evaluations of ML for education (ML4Ed) papers published in preeminent applied ML conferences over the past decade. Our central research goal is to critically examine how the stated or implied education and societal objectives of these papers are aligned with the ML problems they tackle. That is, to what extent does the technical problem formulation, objectives, approach, and interpretation of results align with the education problem at hand? We find that a cross-disciplinary gap exists and is particularly salient in two parts of the ML life cycle: the formulation of an ML problem from education goals and the translation of predictions to interventions. We use these insights to propose an extended ML life cycle, which may also apply to the use of ML in other domains. Our work joins a growing number of meta-analytical studies across education and ML research as well as critical analyses of the societal impact of ML. Specifically, it fills a gap between the prevailing technical understanding of machine learning and the perspective of education researchers working with students and in policy.
Realization of the Brazil-nut effect in charged colloids without external driving
Authors: van der Linden Marjolein N. , Everts Jeffrey C. , van Roij René , van Blaaderen Alfons
Published: February 2023

Sedimentation is a ubiquitous phenomenon across many fields of science, such as geology, astrophysics, and soft matter. Sometimes, sedimentation leads to unusual phenomena, such as the Brazil-nut effect, where heavier (granular) particles reside on top of lighter particles after shaking. We show experimentally that a Brazil-nut effect can be realized in a binary colloidal system of long-range repulsive charged particles driven purely by Brownian motion and electrostatics without the need for activity. Using theory, we argue that not only the mass-per-charge for the heavier particles needs to be smaller than the mass-per-charge for the lighter particles but also that at high overall density, the system can be trapped in a long-lived metastable state, which prevents the occurrence of the equilibrium Brazil-nut effect. Therefore, we envision that our work provides valuable insights into the physics of strongly interacting systems, such as partially glassy and crystalline structures. Finally, our theory, which quantitatively agrees with the experimental data, predicts that the shapes of sedimentation density profiles of multicomponent charged colloids are greatly altered when the particles are charge-regulating with more than one ion species involved. Hence, we hypothesize that sedimentation experiments can aid in revealing the type of ion adsorption processes that determine the particle charge and possibly the value of the corresponding equilibrium constants.
Creating large Fock states and massively squeezed states in optics using systems with nonlinear bound states in the continuum
Authors: Rivera Nicholas , Sloan Jamison , Salamin Yannick , Joannopoulos John D. , Soljačić Marin
Published: February 2023

The quantization of the electromagnetic field leads directly to the existence of quantum mechanical states, called Fock states, with an exact integer number of photons. Despite these fundamental states being long-understood, and despite their many potential applications, generating them is largely an open problem. For example, at optical frequencies, it is challenging to deterministically generate Fock states of order two and beyond. Here, we predict the existence of an effect in nonlinear optics, which enables the deterministic generation of large Fock states at arbitrary frequencies. The effect, which we call an
n
-photon bound state in the continuum, is one in which a photonic resonance (such as a cavity mode) becomes lossless when a precise number of photons
n
is inside the resonance. Based on analytical theory and numerical simulations, we show that these bound states enable a remarkable phenomenon in which a coherent state of light, when injected into a system supporting this bound state, can spontaneously evolve into a Fock state of a controllable photon number. This effect is also directly applicable for creating (highly) squeezed states of light, whose photon number fluctuations are (far) below the value expected from classical physics (i.e., shot noise). We suggest several examples of systems to experimentally realize the effects predicted here in nonlinear nanophotonic systems, showing examples of generating both optical Fock states with large
n
(
n
 >  10), as well as more macroscopic photonic states with very large squeezing, with over 90% less noise (10 dB) than the classical value associated with shot noise.
If I testify about others, my testimony is valid
Authors: Zhao Xin , Mao Yansheng
Published: February 2023

While trustworthiness has been found to exert a vital influence on the success of an online medical crowdfunding (Ba et al. 2021), scarce studies have investigated the concepts and culture of trust in Eastern scenarios like China (Wang 2020). This is the first study aiming to discursively analyze how other-justified discourses, i.e., enhancing objectivity and trustworthiness through other people’s comments, contribute to obtaining potential donors’ trust in Chinese online medical crowdfunding encounters. Through the discourse analysis of 496 other-justified comments on fifty pieces of fully-funded online medical crowdfunding projects, it is found that four different types of people (a family member, a person in the same business or occupation, a classmate, a friend) offer evidence through other-justified discourses oriented towards ethos, experience, and emotion. TheWu-Lun(five ethic orders) in the acquaintance society is the underlying theoretical rationale that supports the credibility of other-justified discourse, which provides a novel research perspective for the dissemination and transitivity of trust in online medical crowdfunding. The findings serve to offer commenters an array of other-justified orientations and identity choices to engage more prospective backers in a medical donative event. The results highlight that crowdfunders not only need to display a compelling narrative strength but also raise awareness to enhance the trustworthiness of their projects, especially focusing on shreds of evidence provided by a third-person comment.
Evaluation of strength in stainless steel weld joints using ball indentation technique
Authors: Pavan A. R. , Ganesh Kumar J. , Arivazhagan B. , Vasudevan M.
Published: February 2023

In the present study, strength variations across the type 316LN stainless steel weld joints processed by advanced hot wire tungsten inert gas, activated tungsten inert gas, and hybrid laser metal inert gas welding processes were evaluated using automated ball indentation technique. The secondary dendrite arm spacing (SDAS) associated with welding heat input and welding thermal cycles strongly influenced the strength properties across the weld joints. The strength properties were lower at 823 K compared to 298 K because of thermally activated deformations. The hybrid laser metal inert gas welding process exhibited significantly narrower weld and higher strength in the weld and heat-affected zone due to finer SDAS and grain size, respectively, than the other weld joints.
Macrophages and bone metastasis
Authors: Di Mitri Diletta , Conforti Fabio , Mantovani Alberto
Published: February 2023

In the prostate bone metastasis microenvironment, macrophages activate a cascade that involves Activin A, the extracellular matrix, and SRC kinase and drives resistance to anti-androgen therapy. These findings (Li et al., 2023. J. Exp. Med.https://doi.org/10.1084/jem.20221007) have broad implications, including metastasis diversity in different tissue milieus and the interplay between hormones and immunity.
The interface of in-situ grown single-layer epitaxial MoS2 on SrTiO3(001) and (111)
Authors: Haastrup Mark J , Bianchi Marco , Lammich Lutz , Lauritsen Jeppe V
Published: February 2023

SrTiO3 (STO) is a versatile substrate with a high dielectric constant, which may be used in heterostructures with 2D materials, such as MoS2, to induce interesting changes to the electronic structure. STO single crystal substrates have previously been shown to support the growth of well-defined epitaxial single-layer (SL) MoS2 crystals. The STO substrate is already known to renormalize the electronic bandgap of SL MoS2, but the electronic nature of the interface and its dependence on epitaxy are still unclear. Herein, we have investigated an in-situ physical vapor deposition (PVD) method, which could eliminate the need for ambient transfer between substrate preparation, subsequent MoS2 growth and surface characterization. Based on this, we then investigate the structure and epitaxial alignment of pristine SL MoS2 in various surface coverages grown on two STO substrates with a different initial surface lattice, the STO(001)(4 × 2) and STO(111)-(9/5 × 9/5) reconstructed surfaces, respectively. Scanning tunneling microscopy shows that epitaxial alignment of the SL MoS2 is present for both systems, reflected by orientation of MoS2 edges and a distinct moiré pattern visible on the MoS2(0001) basal place. Upon increasing the SL MoS2 coverage, the presence of four distinct rotational domains on the STO(001) substrate, whilst only two on STO(111), is seen to control the possibilities for the formation of coherent MoS2 domains with the same orientation. The presented methodology relies on standard PVD in ultra-high vacuum and it may be extended to other systems to help explore pristine two-dimensional transition metal dichalcogenide/STO systems in general.
Operando study of mechanical integrity of high-volume expansion Li-ion battery anode materials coated by Al2O3
Authors: Zhou Xinwei , Stan Liliana , Hou Dewen , Jin Yang , Xiong Hui , Zhu Likun , Liu Yuzi
Published: February 2023

Group IV elements and their oxides, such as Si, Ge, Sn and SiO have much higher theoretical capacity than commercial graphite anode. However, these materials undergo large volume change during cycling, resulting in severe structural degradation and capacity fading. Al2O3 coating is considered an approach to improve the mechanical stability of high-capacity anode materials. To understand the effect of Al2O3 coating directly, we monitored the morphology change of coated/uncoated Sn particles during cycling using operando focused ion beam–scanning electron microscopy. The results indicate that the Al2O3 coating provides local protection and reduces crack formation at the early stage of volume expansion. The 3 nm Al2O3 coating layer provides better protection than the 10 and 30 nm coating layer. Nevertheless, the Al2O3 coating is unable to prevent the pulverization at the later stage of cycling because of large volume expansion.
High-quality vertically aligned InAs nanowires grown by molecular-beam epitaxy using Ag–In alloy segregation
Authors: Liu Lei , Pan Dong , Wen Lianjun , Zhuo Ran , Zhao Jianhua
Published: February 2023

InAs nanowires show important potential applications in novel nanoelectronic devices, infrared optoelectronic devices and quantum devices, and all these applications require controllable growth of the InAs nanowires. However, the growth direction of metal-assisted InAs nanowires on Si substrates is often random. Here, we develop a new approach to grow vertically aligned InAs nanowires on Si (111) substrates by molecular-beam epitaxy using Ag as catalysts. The vertically aligned one-dimensional InAs nanowires are grown on the parasitic two-dimensional InAs film on the Si substrates by using the Ag nanoparticles segregated from Ag–In alloy catalysts. The diameters of the vertically aligned InAs nanowires obtained by this method are mainly distributed between 20 and 50 nm. Detailed transmission electron microscope data show that the nanowires with thinner diameters tend to have less stacking faults and twin defects and high crystal quality pure wurtzite nanowires can be obtained. Using these vertically aligned InAs nanowires as the channel material of field effect transistors, we have obtained a field-effect mobility of ∼2800 cm2 V−1 s−1 and an I
on/I
off ratio of ∼104 at room temperature. Our work provides a new method for the controlled growth of high-quality vertically aligned InAs nanowires on Si substrates.
On the design and development of foamed GO-hydrogel nanocomposite surfaces by ultra-short laser processing
Authors: Mulko Lucinda E , Cuello Emma A , Baumann Robert , Ramuglia Anthony R , Weidinger Inez M , Acevedo Diego F , Barbero Cesar A , Molina Maria , Lasagni Andrés Fabián
Published: February 2023

Graphene oxide (GO) and reduced graphene oxide have outstanding qualities that could be exploited as reinforcement and antibacterial agents in a plethora of biomedical applications. In this contribution, it is reported the deployment of a polyacrylamide GO-hydrogel composite (GO@pAAm) which was photo-converted and structured by ultra-short laser irradiation using a direct laser writing (DLW) approach. The materials were characterized by Fourier Transform Infrared spectroscopy, scanning electron microscopy and confocal microscopy. The laser structure generates a multi-photo-induced effect: surface foaming and patterning, microdomains with enhanced selective water-swelling and effective GO photo-reduction. A first laser scan seems likely to induce the photo-reduction of GO and subsequent laser pulses trigger the structure/foaming. The photo-reduction of GO is evidenced by Raman spectroscopy by the relatively changing intensities of the D to G signals. Macroscopically by an increase in conductivity (decrease in sheet resistance from R
S-GO@pAAm = 304 ± 20 kΩ sq−1 to R
S-rGO@pAAm-DLW = 27 ± 8 kΩ sq−1) suggesting a reduction of the material measured by 4-Point-Probe.
Continuous blood pressure monitoring by photoplethysmography - signal preprocessing requirements based on blood flow modelling
Authors: Poliński Artur
Published: February 2023

Objective. The aim of the study is to investigate the effect of the signal sampling frequency and low-pass filtering on the accuracy of the localisation of the fiducial points of the photoplethysmographic signal (PPG), and thus on the estimation of the blood pressure (i.e. the accuracy of the estimation). Approach. Statistical analysis was performed on 3,799 data samples taken from a publicly available database. Four PPG fiducial points of each sample signal were examined in the study. Main results. Simulation suggests that for noise-free data, cubic spline interpolation causes the sampling frequency (in the considered range of 62.5–500 Hz) to have only limited influence on localisation of the fiducial point. Better results were obtained for the pulse transit time (PTT) than pulse arrival time (PAT) approach. The acceptable filter band depends on the selected fiducial point and PAT or PTT approach. The best results were obtained for the tangent fiducial point. Significance. The presented results make it possible to estimate the minimum requirements for the sampling frequency and filtering of the PPG signal in order to obtain a reliable estimation of blood pressure.
CMOS-compatible manufacturability of sub-15 nm Si/SiO2/Si nanopillars containing single Si nanodots for single electron transistor applications
Authors: von Borany J , Engelmann H-J , Heinig K-H , Amat E , Hlawacek G , Klüpfel F , Hübner R , Möller W , Pourteau M-L , Rademaker G , Rommel M , Baier L , Pichler P , Perez-Murano F , Tiron R
Published: February 2023

This study addresses the complementary metal-oxide-semiconductor-compatible fabrication of vertically stacked Si/SiO2/Si nanopillars (NPs) with embedded Si nanodots (NDs) as key functional elements of a quantum-dot-based, gate-all-around single-electron transistor (SET) operating at room temperature. The main geometrical parameters of the NPs and NDs were deduced from SET device simulations using the nextnano++ program package. The basic concept for single silicon ND formation within a confined oxide volume was deduced from Monte-Carlo simulations of ion-beam mixing and SiO
x
phase separation. A process flow was developed and experimentally implemented by combining bottom-up (Si ND self-assembly) and top-down (ion-beam mixing, electron-beam lithography, reactive ion etching) technologies, fully satisfying process requirements of future 3D device architectures. The theoretically predicted self-assembly of a single Si ND via phase separation within a confined SiO
x
disc of <500 nm3 volume was experimentally validated. This work describes in detail the optimization of conditions required for NP/ND formation, such as the oxide thickness, energy and fluence of ion-beam mixing, thermal budget for phase separation and parameters of reactive ion beam etching. Low-temperature plasma oxidation was used to further reduce NP diameter and for gate oxide fabrication whilst preserving the pre-existing NDs. The influence of critical dimension variability on the SET functionality and options to reduce such deviations are discussed. We finally demonstrate the reliable formation of Si quantum dots with diameters of less than 3 nm in the oxide layer of a stacked Si/SiO2/Si NP of 10 nm diameter, with tunnelling distances of about 1 nm between the Si ND and the neighboured Si regions forming drain and source of the SET.
Thermal thin shell approximation towards finite element quench simulation
Authors: Schnaubelt Erik , Wozniak Mariusz , Schöps Sebastian
Published: February 2023

Superconducting electromagnets commonly exhibit thin layers with high aspect ratio such as insulation layers or turn-to-turn contacts. A finite element (FE) analysis of these devices can lead to unfavorable meshes in these thin layers, either because of a high number of degrees of freedom or mesh elements of poor quality which decrease the accuracy of the simulation results. To mitigate these issues when conducting a thermal FE analysis solving the heat equation, this work proposes to collapse thin volume layers into surfaces by using a thermal thin shell approximation (TSA). The proposed method uses one-dimensional Lagrange elements across the thickness of the thin layer and can handle a variety of interface conditions, multi-layered structures, heat sources, nonlinear material behavior or coupling to physics other than heat transfer. The efficiency of the proposed approximation is highlighted by comparison with a reference model with a conventionally meshed insulation for a model problem exhibiting a brick wall structure where a stationary heat equation is solved. The formulation is then verified against reference models with meshed insulation solving a transient heat equation for an insulated high-temperature superconductor pancake coil exhibiting a local defect which causes a thermal runaway. The benefit of using the model with the TSA is studied by analyzing pancake coils with different ratios of the insulation layer to the coated conductor thickness. It is shown that the smaller the ratio, the shorter the solution time and the lower the number of unknowns of the thin shell model when compared to the conventionally meshed insulation in order to reach the same numerical accuracy. The method is implemented in an open-source FE framework and a reference implementation for a simple model problem is shared alongside this paper.
Dephasing effect promotes the appearance of quantized Hall plateaus
Authors: Fang Jing-Yun , Guo Ai-Min , Sun Qing-Feng
Published: February 2023

The quantum Hall effect (QHE) is a topologically protected phenomenon which has been observed in various systems. In experiments, the size of Hall bar device to realize the QHE is generally much larger than the phase coherence length, in which the quantum coherence of electrons is destroyed. Here, we theoretically study the influence of dephasing effect on the quantized Hall (QH) plateaus. We find that the QH plateaus disappear in perfectly quantum coherent systems if the coupling between leads and central region is imperfect. The Hall resistance is very large and strongly oscillates instead of presenting the QH plateaus in this case. However, by introducing the dephasing, Hall resistance decreases and the QH plateaus appear gradually. Similar results can also be observed for the quantum anomalous Hall effect. Our results propose that dephasing effect promotes the appearance of QH plateaus, which opens a new topic of the dephasing effect on topological systems.
Pulse length effects in long wavelength driven non-sequential double ionization
Authors: Jiang H , Mandrysz M , Sanchez A , Dura J , Steinle T , Prauzner-Bechcicki J S , Zakrzewski J , Lewenstein M , He F , Biegert J , Ciappina M F
Published: February 2023

We present a joint experimental and theoretical study of non-sequential double ionization (NSDI) in argon driven by a 3100 nm laser source. The correlated photoelectron momentum distribution (PMD) shows a strong dependence on the pulse duration, and the evolution of the PMD can be explained by an envelope-induced intensity effect. Determined by the time difference between tunneling and rescattering, the laser vector potential at the ionization time of the bound electron will be influenced by the pulse duration, leading to different drift momenta. Such a mechanism is extracted through a classical trajectory Monte Carlo-based model and it can be further confirmed by quantum mechanical simulations. This work sheds light on the importance of the pulse duration in NSDI and improves our understanding of the strong field tunnel-recollision dynamics under mid-IR laser fields.
Quasi-common-path off-axis interferometric quantitative phase microscopy based on amplitude-division
Authors: Shan Mingguang , Jin Qiqiang , Zhong Zhi , Liu Lei
Published: February 2023

A quasi-common-path off-axis interferometric quantitative phase microscopy (iQPM) is proposed using amplitude-division in this paper. Utilizing a quasi-common-path interferometric module, our method divides the object beam into two copies using a beam-splitter and two mirrors after the output of the microscope, while spatially filters one of the copies to act as the reference beam, and thus yields off-axis interference at the camera plane. The compact module is built using simple optical elements without the requirements of special optical skills and/or complex alignment. In contrast to the previous common-path off-axis iQPMs, the proposed method can flexibly adjust each channel to improve the visibility and/or frequency of the interferogram. Several experimental results are presented to demonstrate the validity and stability of the proposed iQPM.
Microcantilever sensors for biochemical detection
Authors: Wang Jingjing , Xu Baozheng , Zhu Yinfang , Zhao Junyuan
Published: February 2023

Microcantilever is one of the most popular miniaturized structures in micro-electromechanical systems (MEMS). Sensors based on microcantilever are ideal for biochemical detection, since they have high sensitivity, high throughput, good specification, fast response, thus have attracted extensive attentions. A number of devices that are based on static deflections or shifts of resonant frequency of the cantilevers responding to analyte attachment have been demonstrated. This review comprehensively presents state of art of microcantilever sensors working in gaseous and aqueous environments and highlights the challenges and opportunities of microcantilever biochemical sensors.
Zigzag Graphene Nanoribbons and Confluent Supersymmetry
Authors: Contreras-Astorga A , Hernandez-Martinez L , Toscano-Flores L G
Published: February 2023

We studied the behavior of charge carriers in graphene nanoribbons with zigzag edges. We start from free nanoribbons, and by using second-order confluent supersymmetry, we added external magnetic fields perpendicular to the graphene layer. The technique allows us to obtain explicit expressions for the solution of the Dirac equation and gives the transcendental equations that must be solved to obtain the energy spectrum.
Luminescence imaging of helium ions during irradiation to water and to an acrylic block
Authors: Yamamoto Seiichi , Yabe Takuya , Akagi Takashi , Kataoka Jun
Published: February 2023

Although the luminescence images of water and an acrylic block during irradiation of proton and carbon ion beams were measured recently, they were not measured for helium ions. Because the mass of helium ions is four times that of protons and one-third that of carbon ions, different results from protons or carbon ions will be obtained by luminescence imaging. We measured the luminescence images of water and an acrylic block during irradiation of helium ion beams. Imaging was conducted using a cooled charge-coupled device (CCD) camera during the irradiation of helium ion pencil beams at three different energies to a water phantom and an acrylic block in addition to mini-beams of helium ions at four different energies. From the measured luminescence images during irradiation of helium ion pencil beams, we could estimate the ranges of the beams for water and the acrylic block. In the luminescence images of the acrylic block during irradiation of mini-beams of helium ions, we observed the luminescence of mini-beams with Bragg peaks in the images. Luminescence imaging of water and an acrylic block during the irradiation of helium ion beams was possible and could be used for range determination of the beams.
Using Harris Hawk algorithm for experimental study on the hole dilation mechanism during Micro-machining (μM) of Graphene nanoplatelets/Carbon fiber (GnP/C) reinforced polymeric composite
Authors: Vishwakarma Rahul , Kesarwani Shivi , Verma Rajesh Kumar , Debnath Kishore , Davim J Paulo
Published: February 2023

This article highlights the hole generation mechanism in the Graphene nanoplatelets/Carbon fiber (GnP/C) reinforced polymeric composite. The lower conductivity of conventional carbon fiber reinforced polymer (CFRP) composites restricts the μEDM (Micro Electrical discharge machining) test. This limitation is overwhelmed by adding highly conductive GnP powder in the CFR (epoxy) polymer composites. The generation of the drilled hole is possible through the increase in the electrical conductivity of the samples. During μEDM, in order to examine the quality of machined holes in terms of hole dilation (HD), different process constraints such as voltage (80, 120, 160 V), pulse on time (30, 40, 50 s), and weight percentage of GnP (0.25, 1, 1.75%) are evaluated (HD). The hole dilation was significantly influenced by GnP concentration and voltage alteration during the micromachining process. Analysis of Variance (ANOVA) results confirmed that the GnP concentration (67.51%) was the most prominent factor affecting hole dilation. The high-resolution microscopy test was performed to investigate the hole machined surface and damages occur during the micromachining test. The variation in the thermal nature of carbon fabric and resin generates internal stress between the composite material, which results in micro-cracks developed in the laminates. The varying parameters were controlled and optimized through a recently developed nature-inspired metaheuristics algorithm based on the conduct of Harris Hawk (HH). The optimal parametric condition for the hole dilation is voltage (level 1–80 volt), pulse duration (level 1–30 μs), and GnP concentration% (Level 1–0.25). The findings of the validation test demonstrate the application potential of the proposed Harris Hawk algorithm.
Uncertainties in the dosimetric heterogeneity correction and its potential effect on local control in lung SBRT
Authors: Erickson Brett G , Cui Yunfeng , Ackerson Bradley G , Kelsey Christopher R , Yin Fang-Fang , Niedzwiecki Donna , Adamson Justus
Published: February 2023

Objective. Dose calculation in lung stereotactic body radiation therapy (SBRT) is challenging due to the low density of the lungs and small volumes. Here we assess uncertainties associated with tissue heterogeneities using different dose calculation algorithms and quantify potential associations with local failure for lung SBRT. Approach. 164 lung SBRT plans were used. The original plans were prepared using Pencil Beam Convolution (PBC, n = 8) or Anisotropic Analytical Algorithm (AAA, n = 156). Each plan was recalculated with AcurosXB (AXB) leaving all plan parameters unchanged. A subset (n = 89) was calculated with Monte Carlo to verify accuracy. Differences were calculated for the planning target volume (PTV) and internal target volume (ITV) Dmean[Gy], D99%[Gy], D95%[Gy], D1%[Gy], and V100%[%]. Dose metrics were converted to biologically effective doses (BED) using α/β = 10Gy. Regression analysis was performed for AAA plans investigating the effects of various parameters on the extent of the dosimetric differences. Associations between the magnitude of the differences for all plans and outcome were investigated using sub-distribution hazards analysis. Main results. For AAA cases, higher energies increased the magnitude of the difference (ΔDmean of −3.6%, −5.9%, and −9.1% for 6X, 10X, and 15X, respectively), as did lung volume (ΔD99% of −1.6% per 500cc). Regarding outcome, significant hazard ratios (HR) were observed for the change in the PTV and ITV D1% BEDs upon univariate analysis (p = 0.042, 0.023, respectively). When adjusting for PTV volume and prescription, the HRs for the change in the ITV D1% BED remained significant (p = 0.039, 0.037, respectively). Significance. Large differences in dosimetric indices for lung SBRT can occur when transitioning to advanced algorithms. The majority of the differences were not associated with local failure, although differences in PTV and ITV D1% BEDs were associated upon univariate analysis. This shows uncertainty in near maximal tumor dose to potentially be predictive of treatment outcome.
Self-focusing, compression and collapse of ultrashort weakly-relativistic Laguerre–Gaussian lasers in near-critical plasma
Authors: Wilson T C , Sheng Z-M , McKenna P , Hidding B
Published: February 2023

Simultaneous self-focusing and compression of ultrashort weakly-relativistic Laguerre–Gaussian laser pulses in dense plasma is investigated theoretically and numerically. A simple theoretical model is developed and used to identify parameter regimes of interest, and then three-dimensional particle-in-cell simulations are carried out to examine the physics in detail. Rapid self-focusing and compression are observed, leading to pulse collapse even for laser pulse energy at the ten millijoule level. Long-lived ring-shaped post-soliton structures are left at the location of the first collapse, and the residual laser energy is scattered into the plasma. Filamentation and re-focusing occur beyond this point, the structure of which depends on the beam parameters but is observed to be only weakly dependent upon the mode of the laser. Circularly-polarised light is found to produce particulary symmetric plasma density structures. In all cases, bursts of MeV electrons with thermal-like spectra are observed at points of collapse.
Evaluation of urban wetland landscapes based on a comprehensive model — a comparative study of three urban wetlands in Hangzhou, China
Authors: Wang Yue , Yang Guofu , Lu Yijun
Published: February 2023

Urban wetlands constitute an integral part of urban ecosystems. Unsurprisingly, wetland landscapes affect the frequency with which urban residents visit wetland areas. Objectively evaluating the beauty of landscapes and exploring the factors that influence their perceived beauty can inform urban wetland landscape design. This study selects three wetlands located in the core, fringe, and suburban areas of Hangzhou, respectively: Xixi wetland, Tongjian Lake wetland, and Qingshan Lake wetland. To explore the impact of ecological design techniques on the scenic beauty of wetlands, the selected wetlands were used to conduct field investigations. In addition, the wetland landscapes were submitted to public evaluations using scenic beauty estimation (SBE). At the same time, the factors affecting the beauty of the wetland landscape were quantified using the semantic differential (SD) method, and the impact paths of ecological design and plant diversity on scenic beauty were analyzed through the structural equation model (SEM). The results indicated that plant richness, cultural expression, color harmony, and coordination of landscape elements have both a significant and positive impact on the scenic beauty of urban wetlands. By way of contrast, habitat diversity had a significant yet negative impact. Across the three urban wetlands, ecological design techniques were found to significantly improve plant diversity and scenic beauty. This study demonstrated that the application of well-thought-out ecological design methods was conducive to the integration of environmental protection, landscape aesthetics, and the sustainable utilization of urban wetlands in the rapid urbanization process, providing a reference for urban wetland landscape conservation, planning, and design.
Projections of wildfire risk and activities under 1.5 °C and 2.0 °C global warming scenarios
Authors: Peng Xiaobin , Yu Miao , Chen Haishan , Zhou Botao , Shi Ying , Yu Li
Published: February 2023

Wildfires are important ecosystem processes that have a significant impact on terrestrial vegetation, environment, and climate. This study investigates how future wildfire risk and activities could change under 1.5 °C and 2.0 °C warming scenarios relative to pre-industrial levels using a modified McArthur Forest Fire Danger Index (FFDIn) and the CLM4.5-BGC land surface model. Sixteen Earth System Models (ESMs) from CMIP5 and CMIP6 were employed to supply the variables of climate change under low, middle, and high greenhouse emission scenarios in the 1.5 °C and 2.0 °C scenarios. The ensemble means from the FFDIn and results from the CLM4.5-BGC with multiple forcings show that the dry areas in the southwestern US, Brazilian Highlands, and Arabian islands are projected to face higher wildfire risk with larger burned areas and more carbon emissions under a warmer climate. The Congo Basin and part of the Amazon could have a lower wildfire risk with smaller burned areas and less carbon emissions. The absolute changes in the projected FFDIn are small, although large increases are observed in boreal areas, particularly in the winter and spring. Burned area and carbon emissions are projected to increase in general in the boreal area but decrease in northeastern Asia. Compared to the 1.5 °C scenario, the wildfire risk and burned area levels are projected to increase under the 2.0 °C scenario except in the western Amazon. However, fire carbon emissions are projected to decrease more in tropical areas under the 2.0 °C scenario. The different change directions in eastern North America and eastern China produced by the FFDIn and CLM4.5-BGC suggest the potential effect of non-meteorological elements on fire activities.
Double-Standard Moralism: Why We Can Be More Permissive Within Our Imagination
Authors: Cecchinato Mattia
Published: February 2023

Although the fictional domain exhibits a prima facie freedom from real-world moral constraints, certain fictive imaginings seem to deserve moral criticism. Capturing both intuitions, this paper argues for double-standard moralism, the view that fictive imaginings are subject to different moral standards than their real-world counterparts. I show how no account has, thus far, offered compelling reasons to warrant the moral appropriateness of this discrepancy. I maintain that the normative discontinuity between fiction and the actual world is moderate, as opposed to one that leaves fictive engagements wholly exempt from moral evaluations. I propose a way of addressing the gamer’s dilemma that is compatible with a moderate kind of discontinuity. Finally, I contend that the audience is justified in adopting deviant moral attitudes in fictional situations because their consequences largely differ from those that analogous real-world events would have.
Deciphering the genetic architecture of human brain structure and function: a brief survey on recent advances of neuroimaging genomics
Authors: Zhao Xingzhong , Yang Anyi , Zhang Zi-Chao , Yang Yucheng T , Zhao Xing-Ming
Published: February 2023

Brain imaging genomics is an emerging interdisciplinary field, where integrated analysis of multimodal medical image-derived phenotypes (IDPs) and multi-omics data, bridging the gap between macroscopic brain phenotypes and their cellular and molecular characteristics. This approach aims to better interpret the genetic architecture and molecular mechanisms associated with brain structure, function and clinical outcomes. More recently, the availability of large-scale imaging and multi-omics datasets from the human brain has afforded the opportunity to the discovering of common genetic variants contributing to the structural and functional IDPs of the human brain. By integrative analyses with functional multi-omics data from the human brain, a set of critical genes, functional genomic regions and neuronal cell types have been identified as significantly associated with brain IDPs. Here, we review the recent advances in the methods and applications of multi-omics integration in brain imaging analysis. We highlight the importance of functional genomic datasets in understanding the biological functions of the identified genes and cell types that are associated with brain IDPs. Moreover, we summarize well-known neuroimaging genetics datasets and discuss challenges and future directions in this field.