bluuebunny/crossref_metadata_2025 huggingface dataset:
Soziale Medien im Arbeitsverhältnis: Social Media Guidelines: Warum sie wichtig sind
Authors: Gerhard Christoph
Published: December 2023

Soziale Medien sind fast allgegenwärtig. Auch Unternehmen setzen vermehrt soziale Medien zur Verbreitung der eigenen Marke, aber auch zur Kommunikation mit Mitarbeitern und (potenziellen) Kunden bzw. der interessierten Öffentlichkeit ein. Zunehmend verschwimmen die Grenzen zwischen privater und beruflicher Nutzung. Dies erfordert ein Handeln des Arbeitgebers.
Neurorehabilitation for Adults with Brain and Spine Tumors
Authors: Hunter Hanna , Qin Evelyn , Wallingford Allison , Hyon April , Patel Amar
Published: December 2023

Central nervous system (CNS) malignancies (i.e. brain and spine tumors) and their treatments can result in a multitude of neurologic deficits. Patients with CNS malignancies experience physical, cognitive, and psychosocial sequelae that can impact their mobility and quality of life. Neurorehabilitation can play a critical role in maintaining independence, preventing disability, and optimizing safety with activities of daily living. This review provides an overview of the neurorehabilitation approaches for patients with CNS malignancies, neurologic impairments frequently treated, and rehabilitation interventions in various health care settings. In addition, we will highlight rehabilitative outcomes between patients with nononcologic neurologic conditions compared to brain and spine tumors. Finally, we address medical challenges that may impact rehabilitation care in these medically complex cancer patients.
Bones of glass: A strong solution
Authors: Shapiro Maura
Published: December 2023

Glass is known for its brittle nature, but its other strengths make it the perfect platform for bone regeneration.
PEDOT:PSS-coated platinum electrodes for neural stimulation
Authors: Dijk Gerwin , Pas Jolien , Markovic Katarina , Scancar Janez , O'Connor Rodney Philip
Published: December 2023

Safe and long-term electrical stimulation of neurons requires charge injection without damaging the electrode and tissue. A common strategy to diminish adverse effects includes the modification of electrodes with materials that increases the charge injection capacity. Due to its high capacitance, the conducting polymer PEDOT:PSS is a promising coating material; however, the neural stimulation performance in terms of stability and safety remains largely unexplored. Here, PEDOT:PSS-coated platinum (Pt-PEDOT:PSS) microelectrodes are examined for neural stimulation and compared to bare platinum (Pt) electrodes. Microelectrodes in a bipolar configuration are used to deliver current-controlled, biphasic pulses with charge densities ranging from 64 to 255 μC cm−2. Stimulation for 2 h deteriorates bare Pt electrodes through corrosion, whereas the PEDOT:PSS coating prevents dissolution of Pt and shows no degradation. Acute stimulation of primary cortical cells cultured as neurospheres shows similar dependency on charge density for Pt and Pt-PEDOT:PSS electrodes with a threshold of 127 μC cm−2 and increased calcium response for higher charge densities. Continuous stimulation for 2 h results in higher levels of cell survival for Pt-PEDOT:PSS electrodes. Reduced cell survival on Pt electrodes is most profound for neurospheres in proximity of the electrodes. Extending the stimulation duration to 6 h increases cell death for both types of electrodes; however, neurospheres on Pt-PEDOT:PSS devices still show significant viability whereas stimulation is fatal for nearly all cells close to the Pt electrodes. This work demonstrates the protective properties of PEDOT:PSS that can be used as a promising approach to extend electrode lifetime and reduce cell damage for safe and long-term neural stimulation.
Effects of polarization-charge shielding and electromagnetic resonances on water behavior under microwave heating
Authors: Liu L. C. , Liang J. C. , Chen K. W. , Chu K. R.
Published: December 2023

Microwave heating of water-rich solvents is a widely used processing technique in research and applications. High-quality outcome requires a uniform temperature environment; which, in turn, depends on the balancing of a variety of effects taking place during the heating. Here, we show that two inherent effects, namely, polarization-charge shielding and electromagnetic resonances, play a critical role in shaping up the field pattern in the heated water sample. Polarization-charge shielding produces an internal electric field sensitive to the sample size, shape, and orientation. Internal electromagnetic resonances result in a widely varying electric field, while also allowing much deeper field penetration than the attenuation length to allow large-scale treatment. The key to temperature uniformity, thus, lies in an optimized thermal flow to balance the non-uniform energy deposition. These complicated processes are examined in simulation and interpreted physically. It is shown that a spherical sample is most favorable for obtaining a high temperature uniformity mainly because of its rotational symmetry. This conclusion is significant in that prevailing sample vessels are mostly non-spherical.
Theoretical study on the pressure expansion mechanism of diffused self-pumping hydrodynamic mechanical seal
Authors: Zheng Wei , Sun Jianjun , Ma Chenbo , Yu Qiuping
Published: December 2023

The pressure expansion performance is the key and basis for the diffused self-pumping hydrodynamic mechanical seal to achieve its good cooling performance, self-cleaning performance, and sealing performance. Using the moment of momentum theorem and Stodola's formula, the pressurization effect of the spiral groove on the fluid was analyzed, and the energy head equation of the work done by the spiral groove on the fluid is established. According to the principle of conservation of energy, the energy equation and Bernoulli equation of the work done by the spiral groove on the fluid are derived, the mathematical expression of the conversion of fluid kinetic energy into hydrostatic pressure in the diffuser groove was established, the energy change and energy distribution problems of the fluid after the work of the spiral groove are clarified, and the pressure expansion mechanism is revealed. Through numerical simulation, the relationship between the fluid pressure at the sealing interface, the position and size of the high-pressure field, the opening force, and the leakage rate under different rotational speeds and the structural parameters of the diffuser groove were explored. Finally, the pressure expansion performance of the ordinary self-pumping hydrodynamic mechanical seal and diffused self-pumping hydrodynamic mechanical seal is compared. The results show that the diffuser groove can effectively convert part of the fluid kinetic energy into pressure energy, improve the opening force of the sealing interface, and have a good pressurization effect on the sealing end face. With the widening of the diffuser groove, the pressure peak of the sealing interface increases, the high-pressure field area continues to expand and tends to expand toward the outer diameter of the seal ring, and the opening force also increases significantly; increasing the depth of the diffuser groove will cause the pressure peak of the sealing interface to become smaller, and the area of the high-pressure field will also decrease rapidly, which is not conducive to improving the opening force of the sealing end face.
Unveiling the non-equilibrium process in multilayer mixture adsorption
Authors: Yu Hsin-Chen , Zhang Xiaoping , Cao Nailiang , Kan Ruifeng , Xu Yi , Ren Zhongzhou
Published: December 2023

The Brunauer–Emmett–Teller (BET) theory [S. Brunauer et al., “Adsorption of gases in multimolecular layers,” J. Am. Chem. Soc. 60, 309–319 (1938)] constitutes a cornerstone in gas-adsorption physics. Recently, the kinetic BET equation of single-kind adsorbate has been proposed [H. Yu and X. Zhang, “Molecular-kinetic study of multilayers gas-adsorption in a rarefied gas environment,” Phys. Fluids 34, 123106 (2022)], while its counterpart of mixed adsorbates is currently unknown. Gas mixtures are commonly found in both natural and artificial systems. To address this limitation, we have proposed a kinetic BET theory for adsorbate mixtures in this paper. Moreover, we gave an analytical solution addressing low gas pressure conditions. In this condition, we predicted the “over-adsorption” of one species in the mixture with a higher desorption rate over time, and the “inertia effect” during the crowed-out process of the fast-desorbing species. Further, we also simulated the reciprocal influence of multilayer gas adsorption on the non-equilibrium fluids. Our findings provide valuable insights into gas-adsorption experiments and can facilitate technological advancements.
Current modified higher-order Schrödinger equation of broader bandwidth capillary-gravity waves
Authors: Pal Tanmoy , Dhar Asoke Kumar
Published: December 2023

A higher-order nonlinear Schrödinger equation of capillary-gravity waves for broader bandwidth on infinite depth of water including the effect of depth uniform current is established. The derivation is made from Zakharov's integral equation by extending the narrow bandwidth restriction to make it more suited for application to problems involving actual sea waves. On the basis of this equation, a stability analysis is made for uniform Stokes waves. After obtaining an instability condition, instability regions in the perturbed wave number space are displayed that are in good agreement with the exact numerical findings. It is found that the modifications in the stability characteristics at the fourth-order term are due to the interaction between the frequency-dispersion term and the mean flow. It is seen that the growth rate of sideband instability decreases due to the effects of both surface tension and depth uniform following currents. Significant deviations of the instability regions are observed between narrow-banded and broader-banded results. In addition, we have depicted the instability growth rate for the case of pure capillary waves.
Thin-film polymeric metasurfaces for visible wavelengths
Authors: Biabanifard Mohammad , Xiao Jianling , Di Falco Andrea
Published: December 2023

Photonic metasurfaces are typically realized by the periodic distribution of meta-atoms, which incorporate two or more different materials. This requirement introduces constraints in the design and fabrication that are particularly significant for flexible and conformable metasurfaces. Here, we report on the design and fabrication of efficient, polarization-independent, all-polymeric metasurface membranes for holographic applications in the visible range. These results will facilitate the large-scale production of holographic metasurfaces, advancing their adoption in practical, real-life scenarios.
Revealing evolutions of intermetallics in a solder joint under electromigration: A quasi-in situ study combining 3D microstructural characterization and numerical simulation
Authors: Yuan H. Y. , Li C. , Zhang H. Z. , Fan M. Z. , Ma Z. L. , Cheng X. W.
Published: December 2023

The evolution of primary and interfacial intermetallic compounds in solder joints during electromigration (EM) significantly influences the mechanical properties and reliability of solder joints. In this work, by combining high-resolution x-ray computed tomography and finite element modeling, the 3D evolution of Cu6Sn5 in a solder joint containing a single β-Sn grain with representative orientation was revealed. It is found that the growth of primary Cu6Sn5 rods and the formations of Cu6Sn5 rods/particles within the matrix and on the anode/cathode interfaces are all heavily influenced by local Cu concentrations and Cu diffusion fluxes in β-Sn, which are controlled by the β-Sn orientation and geometry of the solder joint. The unobvious growth of some Cu6Sn5 is also attributed to the high angles between [0001]Cu6Sn5 and [001]β-Sn (>45°). The orientation relationship between β-Sn and Cu6Sn5 also contributes to the growth direction of the newly formed Cu6Sn5 rod. This study provides insight into the mechanisms of EM-induced microstructure evolutions in ball-grid-array solder joints.
High electrical characteristics through graphene oxide doping process on physicochemically reformed inorganic thin films
Authors: Yang Da-Bin , Oh Jin Young , Choi Bo-Kyeong , Lee Dong Wook , Kim Dong Hyun , Seo Dae-Shik
Published: December 2023

This study investigated the improvement of the electro-optical properties of a liquid crystal (LC) cell fabricated through brush coating using graphene oxide (GO) doping. The physical deformation of the surface was analyzed using atomic force microscopy. The size of the groove increased as the GO dopant concentration increased, but the direction of the groove along the brush direction was maintained. X-ray photoelectron spectroscopy analysis confirmed that the number of C–C and O–Sn bonds increased as the GO concentration increased. Since the van der Waals force on the surface increases as the number of O–metal bonds increases, we were able to determine why the anchoring energy of the LC alignment layer increased. This was confirmed by residual DC voltage and anchoring energy measurements that were later performed. As the GO concentration increased, the width of the hysteresis curve decreased, indicating that the residual DC voltage decreased. Additionally, the 15% GO-doped sample exhibited a significant increase in its anchoring energy up to 1.34 × 10−3 J/m2, which is similar to that of rubbed polyimide. It also secured a high level of electro-optical properties and demonstrated potential as a next-generation thin-film display despite being produced via a simple brush-coating process.
Peristaltic flow of a bioconvective sutterby nanofluid in a flexible microchannel with compliant walls: Application to hemodynamic instability
Authors: Ajithkumar M. , Vajravelu K. , Sucharitha G. , Lakshminarayana P.
Published: December 2023

A theoretical investigation is conducted for bioconvective peristaltic transport of a non-Newtonian nanofluid through a porous symmetric channel with compliant walls. The Sutterby nanofluid model is utilized to characterize the fluid under an applied magnetic field. The use of radiative heat flux along with the heat source and the thermodynamics energizes the flow phenomena. In addition, the novelty of the present study is to analyze the behavior of bioconvective Sutterby nanofluid in a chemically reactive porous channel with heat and mass transfer aspects. To reduce the complexity of the system, we used a long wavelength and low Reynolds number approximation. Furthermore, to tackle the dimensionless equations related to the flow phenomena, numerical computations are performed by utilizing MATLAB's built-in bvp5c function. The consequences of the pertinent parameters on the flow characteristics are presented through tables and graphs. An increase in both the Darcy number and the buoyancy ratio parameters raises the velocity distribution of a Sutterby nanofluid. The magnitude of the thermal field is enhanced in a symmetric channel with a rising Eckert number and the energy generation parameter. The thermophoresis diffusion parameter strengthens the temperature profile but decreases the concentration of the Sutterby nanofluid. We believe that the outcomes of this study have a wide range of implications to targeted drug delivery, the pharmaceutical industry, thermal devices, biosensors, sustainable fuel cell technologies, and solar systems.
Electric-field modulation of the charge-density-wave quantum condensate in h-BN/NbS3 quasi-2D/1D heterostructure devices
Authors: Taheri Maedeh , Sesing Nicholas , Salguero Tina T. , Balandin Alexander A.
Published: December 2023

We report on the field-effect modulation of the charge-density-wave quantum condensate in the top-gated heterostructure devices implemented with quasi-one-dimensional NbS3 nanowire channels and quasi-two-dimensional h-BN gate dielectric layers. The charge-density-wave phases and collective current in quasi-1D NbS3 nanowires were verified via temperature dependence of the resistivity, non-linear current–voltage characteristics, and Shapiro steps that appeared in the device response under radio frequency excitation mixed with the DC bias. It was demonstrated that the electric field of the applied gate bias can reversibly modulate the collective current of the sliding charge-density-wave condensate. The collective current reduces with more positive bias, suggesting a surface effect on the condensate mobility. The single-particle current, at small source–drain biases, shows small-amplitude fluctuation behavior, attributed to the variations in the background potential due to the pinned or creeping charge-density-wave condensate. The knowledge of the electric-field effect on the charge density waves in quasi-1D NbS3 nanowires is useful for potential electronic applications of such quantum materials.
Structures of theP. aeruginosaFleQ-FleN master regulators reveal large-scale conformational switching in motility and biofilm control
Authors: Torres-Sánchez Lucía , Géry Sana Thibault , Decossas Marion , Hashem Yaser , Krasteva Petya Violinova
Published: December 2023

Pseudomonas aeruginosacan cause a wide array of chronic and acute infections associated with its ability to rapidly switch between planktonic, biofilm, and dispersed lifestyles, each with a specific arsenal for bacterial survival and virulence. At the cellular level, many of the physiological transitions are orchestrated by the intracellular second messenger c-di-GMP and its receptor-effector FleQ. A bacterial enhancer binding protein, FleQ acts as a master regulator of both flagellar motility and adherence factor secretion and uses remarkably different transcription activation mechanisms depending on its dinucleotide loading state, adenosine triphosphatase (ATPase) activity, interactions with polymerase sigma (σ) factors, and complexation with a second ATPase, FleN. How the FleQ-FleN tandem can exert diverse effects through recognition of a conserved FleQ binding consensus has remained enigmatic. Here, we provide cryogenic electron microscopy (cryo-EM) structures of both c-di-GMP-bound and c-di-GMP-free FleQ-FleN complexes which deepen our understanding of the proteins’ (di)nucleotide-dependent conformational switching and fine-tuned roles in gene expression regulation.
An mTurq2-Col4a1 mouse model allows for live visualization of mammalian basement membrane development
Authors: Jones Rebecca A. , Trejo Brandon , Sil Parijat , Little Katherine A. , Pasolli H. Amalia , Joyce Bradley , Posfai Eszter , Devenport Danelle
Published: December 2023

Basement membranes (BMs) are specialized sheets of extracellular matrix that underlie epithelial and endothelial tissues. BMs regulate the traffic of cells and molecules between compartments, and participate in signaling, cell migration, and organogenesis. The dynamics of mammalian BMs, however, are poorly understood, largely due to a lack of models in which core BM components are endogenously labeled. Here, we describe the mTurquoise2-Col4a1 mouse in which we fluorescently tag collagen IV, the main component of BMs. Using an innovative planar-sagittal live imaging technique to visualize the BM of developing skin, we directly observe BM deformation during hair follicle budding and basal progenitor cell divisions. The BM’s inherent pliability enables dividing cells to remain attached to and deform the BM, rather than lose adhesion as generally thought. Using FRAP, we show BM collagen IV is extremely stable, even during periods of rapid epidermal growth. These findings demonstrate the utility of the mTurq2-Col4a1 mouse to shed new light on mammalian BM developmental dynamics.
Electronic and elastic correlations in AlB2-type two-dimensional hexagonal MBenes
Authors: Sharma Ashish , Rangra Vir Singh
Published: December 2023

With the advent of MXenes as two-dimensional (2D) materials beyond graphene, non carbonic 2D materials analogically referred as MBenes have significantly attracted researchers’ attention. Such 2D MBenes remains largely unexplored. Here, we systematically investigate electronic and elastic properties of 2D transition metal (TM) based AlB2-type hexagonal MBenes consisting of a honeycomb networked graphene like boron layer embedded with diverse TM atoms at center. First we determine the thermodynamic, dynamic, thermal, and mechanical stability of MBenes, considering a wide range of 3d, 4d, and 5d TM elements. Electronic and elastic calculations are performed for stable MBenes in order to parameterize and investigate the interdependence of properties. Elastic calculations predicts the brittle-ductile nature and bond character of MBenes while unraveling the in-plane auxetic behavior. Our electronic calculations predict the metallic band nature for 2D VB2, NbB2, TaB2, and WB2 along with previously reported dirac points in 2D TiB2, FeB2, ZrB2, and HfB2. The elastic and electronic calculations clearly indicates the non-directional metallic bonds and intrinsically ductile nature of 2D-FeB2 distinct from other MBenes. Subsequently we performed a covariance analysis to assess the correlation amongst the observables of interest and further establish the interdependence of the properties. Our calculations for elastic correlations also suggests that mechanical brittle-ductile nature and auxetic behavior of MBenes can be tuned by strain engineering of the elastic constants. Our results further suggests that strong correlations between Poisson ratio and d state electrons can be utilized to tune the auxetic behavior by careful doping of the materials. Our work demonstrates the weak elastic-electronic correlations, suggesting that the strain engineering can be utilized for the tailored behavior of MBenes for practical applications. Thus, our systematic analysis of the mechano-elastic and electronic properties of 2D hexagonal MBenes and their correlations advance our understandings of emergent 2D family.
Research on the measurement method of crankshaft coaxiality error based on three-dimensional point cloud
Authors: Dou Yaping , Zheng Shu , Ren Huiru , Gu Xuhui , Sui Wentao
Published: December 2023

Aiming at the demand of rapid detection for coaxiality of crankshaft journal, a method of visual measurement of coaxiality error based on 3D point cloud is proposed. In this research, a laser scanner is utilized to obtain a 3D point cloud model of the part to be measured, and a circular method of rotary cutting is put forward to obtain equally spaced optimal slices of the journal. The center of the slice is then obtained using the Pratt circle fitting method optimized in this paper. After that, the center of the slice is used to obtain the common reference axis using the least squares method, which finally realizes the measurement of the coaxiality error. The experimental results show that the proposed method of getting the slices is more accurate, the maximum absolute error of the circle fitting method compared with the results of the coordinate measuring machine (CMM) is no more than 4.2 μm, and the maximum absolute error of the coaxiality detection results and the results of the CMM is 5.5 μm, which can satisfy the practical needs of fast and efficient measurement of the coaxiality error of crankshafts.
Estimation of rolling bearing remaining useful life using DReLU-RA-ConvGRU model based on the encoder–decoder structure
Authors: Wu Qile , Xiao Ke , Xiong Wanquan , Han Yanfeng , Song Bin
Published: December 2023

Rolling bearings serve as indispensable core components in modern industrial equipment and they are critical for safety and reliability. Consequently, accurate prediction of their remaining useful life (RUL) is essential and has far-reaching implications. This paper proposes a novel RUL prediction model, referred to as the dynamic rectified linear unit-based residual additive attention ConvGRU (DReLU-RA-ConvGRU) model, which is built upon the encoder–decoder structure to accurately predict the RUL of bearings. To overcome the limitation of the original signal, characterized by a single feature and limited degradation information, three-domain features are employed and filtered as inputs to the model. The DReLU component in the proposed RUL prediction model effectively captures variable feature information within the degraded signal, while the ConvGRU component learns both temporal and spatial information with fewer parameters. Additionally, the RA component captures the significant contributors to RUL prediction, and the inclusion of residuals facilitates easier network learning. Furthermore, a three-dimensional visualization of the attention weights was conducted to enhance the interpretability of the network’s prediction process. In order to verify the effectiveness of the method, RUL prediction was conducted using vibration data from the PRONOSTIA platform and compared against several existing methods. The results demonstrate the method’s superior performance and feasibility, as indicated by high scores.
Hyperspectral photoluminescence and reflectance microscopy of 2D materials
Authors: Tebbe David , Schütte Marc , Kundu Baisali , Beschoten Bernd , Sahoo Prasana K , Waldecker Lutz
Published: December 2023

Optical micro-spectroscopy is an invaluable tool for studying and characterizing samples ranging from classical semiconductors to low-dimensional materials and heterostructures. To date, most implementations are based on point-scanning techniques, which are flexible and reliable, but slow. Here, we describe a setup for highly parallel acquisition of hyperspectral reflection and photoluminescence (PL) microscope images using a push-broom technique. Spatial as well as spectral distortions are characterized and their digital corrections are presented. We demonstrate close- to diffraction-limited spatial imaging performance and a spectral resolution limited by the spectrograph. The capabilities of the setup are demonstrated by recording a hyperspectral PL map of a MoSe2–WSe2 lateral heterostructure, grown by chemical vapor deposition (CVD), from which we extract the luminescence energies, intensities and peak widths across the interface.
The realisation of admissible graphs for coupled vector fields
Authors: Amorim Tiago de Albuquerque , Manoel Miriam
Published: December 2023

In a coupled network cells can interact in several ways. There is a vast literature from the last 20 years that investigates this interacting dynamics under a graph theory formalism, namely as a graph endowed with an input-equivalence relation on the set of vertices that enables a characterisation of the admissible vector fields that rules the network dynamics. The present work goes in the direction of answering an inverse problem: for

n
⩾
2

, any mapping on

R

n

can be realised as an admissible vector field for some graph with the number of vertices depending on (but not necessarily equal to) n. Given a mapping, we present a procedure to construct all non-equivalent admissible graphs, up to the appropriate equivalence relation. We also give an upper bound for the number of such graphs. As a consequence, invariant subspaces under the vector field can be investigated as the locus of synchrony states supported by an admissible graph, in the sense that a suitable graph can be chosen to realise couplings with more (or less) synchrony than another graph admissible to the same vector field. The approach provides in particular a systematic investigation of occurrence of chimera states in a network of van der Pol identical oscillators.
Invariant measures for a stochastic nonlinear and damped 2D Schrödinger equation
Authors: Brzeźniak Zdzisław , Ferrario Benedetta , Zanella Margherita
Published: December 2023

We consider a stochastic nonlinear defocusing Schrödinger equation with zero-order linear damping, where the stochastic forcing term is given by a combination of a linear multiplicative noise in the Stratonovich form and a nonlinear noise in the Itô form. We work at the same time on compact Riemannian manifolds without boundary and on relatively compact smooth domains with either the Dirichlet or the Neumann boundary conditions, always in dimension two. We construct a martingale solution using a modified Faedo–Galerkin’s method, following Brzeźniak et al (2019 Probab. Theory Relat. Fields
174 1273–338). Then by means of the Strichartz estimates deduced from Blair et al (2008 Proc. Am. Math. Soc.
136 247–56) but modified for our stochastic setting we show the pathwise uniqueness of solutions. Finally, we prove the existence of an invariant measure by means of a version of the Krylov–Bogoliubov method, which involves the weak topology, as proposed by Maslowski and Seidler (1999 Atti Accad. Naz. Lincei Cl. Sci. Fis. Mat. Natur. Rend. Lincei (9) Mat. Appl.
10 69–78). This is the first result of this type for stochastic nonlinear Schrödinger equation (NLS) on compact Riemannian manifolds without boundary and on relatively compact smooth domains even for an additive noise. Some remarks on the uniqueness in a particular case are provided as well.
Surface-based anthropomorphic bone structures for use in high-resolution simulated medical imaging
Authors: Sauer Thomas J , McCabe Cindy , Abadi Ehsan , Samei Ehsan , Segars W Paul
Published: December 2023

Objective. Virtual imaging trials enable efficient assessment and optimization of medical image devices and techniques via simulation rather than physical studies. These studies require realistic, detailed ground-truth models or phantoms of the relevant anatomy or physiology. Anatomical structures within computational phantoms are typically based on medical imaging data; however, for small and intricate structures (e.g. trabecular bone), it is not reasonable to use existing clinical data as the spatial resolution of the scans is insufficient. In this study, we develop a mathematical method to generate arbitrary-resolution bone structures within virtual patient models (XCAT phantoms) to model the appearance of CT-imaged trabecular bone. Approach. Given surface definitions of a bone, an algorithm was implemented to generate stochastic bicontinuous microstructures to form a network to define the trabecular bone structure with geometric and topological properties indicative of the bone. For an example adult male XCAT phantom (50th percentile in height and weight), the method was used to generate the trabecular structure of 46 chest bones. The produced models were validated in comparison with published properties of bones. The utility of the method was demonstrated with pilot CT and photon-counting CT simulations performed using the accurate DukeSim CT simulator on the XCAT phantom containing the detailed bone models. Main results. The method successfully generated the inner trabecular structure for the different bones of the chest, having quantiative measures similar to published values. The pilot simulations showed the ability of photon-counting CT to better resolve the trabecular detail emphasizing the necessity for high-resolution bone models. Significance. As demonstrated, the developed tools have great potential to provide ground truth simulations to access the ability of existing and emerging CT imaging technology to provide quantitative information about bone structures.
Characterizing piezoelectric properties of PVDF film under extreme loadings
Authors: Yu Yao , Li Jialin , Xie Zihao , Gong Xiaobo , Gao Guangjun , Wang Jiabin , Li Jian
Published: December 2023

Polyvinylidene fluoride (PVDF) as a polymer has been proven to be an effective piezoelectric sensor with advantages of good flexibility, high mechanical strength, and high chemical resistance. Numerous studies have focused on the response of PVDF film at high strain rates, but few on low strain rate response, and the response of PVDF film at different strain rates is unknown. To address these limitations, we examine the piezoelectric properties of PVDF film at extreme high and low loading rates. We design quasi-static compression and dynamic split Hopkinson pressure bar (SHPB) test setups to examine the response of PVDF film. Quasi-static compression test results show that PVDF films have good repeatability and linearity. The charge shift phenomenon is observed at quasi-static loading conditions, and the charge shift rate is found to be related to the gain coefficient of charge amplifier. Next, SHPB tests are performed and results show that PVDF film can well capture the propagation of stress wave. Moreover, it is observed that the PVDF film under high loading rate has a higher failure strength in comparison to that of low loading rate. Finally, based on the measured points by quasi-static compression and SHPB tests, the piezoelectric coefficients of PVDF film under extreme low (on the scale of strain rate of 10−2 s−1) and extreme high (on the scale of strain rate 105 s−1) loading rates are found to be 30.79 pC/N and 27.72 pC/N, respectively. Note that, the strain rate difference is seven orders of magnitude, the piezoelectric coefficient difference is only 9.97%. We believe our findings can advance the design and application of PVDF films in practical engineering.
Fractal design of 3D-printing mechanical metamaterial undergoing tailorable zero Poisson’s ratio
Authors: Liu Yuheng , Lu Haibao , Lau Denvid
Published: December 2023

With the development of mechanical metamaterials, structures with large and nonlinear deformations have attracted great research passions for their increasingly applications. Although it has been studied for decades, the mechanics of conflict between large deformation with non-buckling has not been well understood. In this study, a new type of mechanical metamaterial, of which the large deformation is achieved without buckling, has been proposed to achieve the zero Poisson’s ratio using fractal design. Effects of fractal iteration (

i

) and connection angle (

α

) on the Poisson’s ratio and mechanical stress-strain behaviors of 3D printing mechanical metamaterial were studied by finite element analysis and experimental tests. Finally, constitutive relationships among loading force, Poisson’s ratio, iteration time and connection angle have been explored and discussed to achieve a large and non-buckling deformation.
Magnetorheological effect and sensing performance of graphite sheet filled PDMS based magnetorheological elastomer under compression
Authors: Qin Xiaobin , Zhang Jiangtao , Guo Xiang , Zhang Mei , Zhai Pengcheng
Published: December 2023

In order to study the effect of large-sized graphite (Gr) sheet on the magnetorheological (MR) effect and sensing characteristics of MR elastomer (MRE), isotropic and anisotropic Gr-filled MRE samples with different carbonyl iron powder (CIP) contents were fabricated. The effect of Gr sheet on the microstructure, MR effect and sensing characteristics of the MRE samples were experimentally tested, and the mechanisms behind discussed. The results show that in the anisotropic MRE samples, the addition of Gr sheets results in the short particle chains formed between Gr sheets, thus leading to the high MR effect and low resistivity than those of isotropic counterparts. The non-monotonic resistivity responses of the Gr-filled MRE samples during compression were observed owing to the interlayer separation of Gr sheets and the reconstruction of conductive network. A higher piezoresistive response was observed from the isotropic Gr-filled MRE sample filled with the CIP content below the percolation threshold. The resistivities of the Gr-filled MRE samples decline with increasing the applied magnetic field. The isotropic sample filled with lower CIP content shows the higher magnetoresistive effect from the view point of absolute change in resistivity. While for the relative change in resistivity, the anisotropic sample filled with the higher CIP content has the higher magnetoresistive effect.
Dynamical behavior of a particle-doped multi-segment dielectric elastomer minimal energy structure
Authors: Gong Jiajie , Han Yubing , Wu Jinbo , Hu Guohui
Published: December 2023

The dynamic behavior of dielectric elastomers (DEs) has significant influence on their performance. The present study investigates the nonlinear dynamics of particle-doped multi-segmented DE minimum energy structures (DEMESs). To simulate the multi-segment DEMES, we consider each segment as a combination of hyperelastic film and elastic beam and obtain the ordinary differential equations governing the system dynamics based on the Euler–Lagrange equations. Due to the difficulty in measuring various physical parameters of DEs in practice, we utilize experimental data from a single-segment DE and employ a physics-informed neural network to predict the unknown parameters of the DE and the framework, such as stiffness K

bb
and doping volume fraction ϕ. Based on these predictions, nonlinear analysis is performed for the multi-segment system. Stability analyses of the motion equations reveal that the system exhibits a supercritical pitchfork bifurcation with hyperelastic thin film pre-stretching as the bifurcation parameter. For the three-segment DEMES, there are eight stable modes, but only four are illustrated in the bifurcation diagram due to the identical parameter settings for each segment. The amplitude-frequency curves under different AC voltage loads indicate the presence of harmonic, superharmonic, and subharmonic resonances in the system, with varying frequencies and magnitudes depending on the applied load. The Poincaré maps of the time response demonstrate that the system response is predominantly quasiperiodic. Under low voltage loads, the system exhibits periodic oscillations, while under certain high voltage loads, chaotic behavior emerges, characterized by strong nonlinearity in the time-dependent curves and non-periodicity in the Poincaré maps. This study provides insights into the present mathematical model in the motion control of DEMES.
A multi-directional broadband piezoelectric-electromagnetic-magnetic coupling compound energy harvester for vibration energy harvesting applications
Authors: Gao Mingming , Zhu Yongqiang , Li Donglin , Liu Hao , Guo Qiang
Published: December 2023

Currently, common vibration energy harvesters can only capture vibration energy in a unidirectional or fixed plane, posing issues such as high collection frequency, limited frequency range, and low output power. This paper proposes a multi-directional broadband piezoelectric-electromagnetic-magnetic coupling composite vibration energy harvester. It achieves three-directional energy harvesting while broadening the harvesting frequency and having a higher power density compared to current state-of-the-art research. Comprising a piezoelectric system and an electromagnetic system, the harvester leverages theoretical analysis to design the piezoelectric cantilever beam with a branching structure, enhancing its broad frequency characteristics. In addition, the magnetic coupling effect is added to the device so that the cantilever beam in three directions can work when the device receives unidirectional vibration excitation. Building on theoretical analysis, the COMSOL 5.6 software is utilized to conduct simulation analysis and optimize the size of the designed piezoelectric cantilever beam structure. This process validates theoretical analysis accuracy and improves energy capture capability. To confirm device viability and simulation accuracy, a physical model is fabricated, and vibration tests are executed. The energy harvester generates two peaks (10 Hz, 27 Hz) when vibration excitation is applied, which effectively broadens the collection frequency. Under the vibration frequency excitation in the X and Y directions, the total composite output power of the multidirectional broadband piezoelectric-electromagnetic-magnetic coupling composite vibration energy harvester is 17.72 mW and 30.22 mW, and the power density can reach 32.85 mW·cm−3, which significantly strengthened the captured energy efficiency of the energy harvester compared with the energy harvester without magnetic coupling, with the total composite output power increased by 352.0% and 165.8%, respectively; under the excitation of the Z-direction vibration frequency, the total composite output power was 42.42 mW and 44.80 mW, and the power density could reach 48.70 mW·cm−3.
On the synthesis methodologies to prepare ‘Pb9Cu(PO4)6O’: phase, composition, magnetic analysis and absence of superconductivity
Authors: Thakur Gohil S , Schulze Manuel , Ruck Michael
Published: December 2023

We present the results of our various attempts to prepare the purported room-temperature and ambient-pressure superconducting compound ‘Pb9Cu(PO4)6O’ (LK-99). We experimented with various starting materials and used several synthesis techniques, such as reactions in sealed silica tubes or sintering in air, to prepare the reported phase. Repetition of the exact synthesis procedure reported by Lee et al failed to reproduce the superconducting phase yielding only a multiphase sample. None of our prepared samples exhibit Meissner effect or levitation. Very importantly, only a small amount of copper was detected in the samples of the phase designated ‘LK-99’. Dark gray flakes were found in some samples that reacted to a permanent magnet at room temperature, reminiscing of ‘half-levitation.’ Magnetic measurement reveal that all samples are diamagnetic in the temperature range of 2–325 K. At 2 K, a weak soft ferromagnetic behavior is observed, the origin of which is unknown.
Nonlinear equilibria and transport processes in burning plasmas
Authors: Falessi Matteo Valerio , Chen Liu , Qiu Zhiyong , Zonca Fulvio
Published: December 2023

In this work, we put forward a general phase space transport theory in axisymmetric tokamak plasmas based upon the concept of zonal state (ZS). Within this theoretical framework, the ZS corresponds to a renormalized plasma nonlinear equilibrium consisting of phase space zonal structures (PSZS) and zonal electromagnetic fields (ZFs) which evolve self-consistently with symmetry breaking fluctuations and sources/collisions. More specifically, our approach involves deriving governing equations for the evolution of particle distribution functions (i.e, PSZS), which can be used to compute the corresponding macro-/meso-scale evolving magnetized plasma equilibrium adopting the Chew Goldberger Low description, separating the spatiotemporal microscale structures. The nonlinear physics of ZFs and of geodesic acoustic modes (GAMs)/energetic particle driven GAMs is then analyzed to illustrate the applications of our theory.
General quantum secure multiparty computation protocol for simultaneous summation and multiplication
Authors: Li Fulin , Luo Mei , Zhu Shixin , Pang Binbin
Published: December 2023

Quantum secure multiparty computation occupies an important place in quantum cryptography. Based on access structure and linear secret sharing, we propose a new general quantum secure multiparty computation protocol for simultaneous summation and multiplication in a high-dimensional quantum system. In our protocol, each participant within any authorized sets only needs to perform local Pauli operation once on the generalized Bell state, then the summation and multiplication results can be output simultaneously, which improves the practicality of the protocol. Moreover, in the privacy computation phase, the decoy particle detection technique as well as the addition of random numbers are applied to blind the privacy information, making our protocol higher privacy protection. Security analysis shows that our protocol is resistant to a series of typical external attacks and dishonest internal participant attacks such as individual attack and collusion attack. Finally, compared with the existing protocols, our protocol not only has higher efficiency but also lower consumption.
On complex fractal-fractional order mathematical modeling of CO
2 emanations from energy sector
Authors: Shah Kamal , Abdeljawad Thabet
Published: December 2023

This research work is devoted to undertake a mathematical model for emissions of carbon dioxide (CO
2) from energy sector using the concept of fractals-fractional differential (FFD) operator. Here, it should be kept in mind that as the population is expanding, so the need of energy increasing day by day. Burning fossil fuels accounts for a sizable amount of the world’s energy production, which increases the concentration of CO
2 in the atmosphere and causes the global warming. It’s critical to reduce CO
2 emissions from the energy industry. Therefore, via the use of FFD operator, we investigate a mathematical model which is addressing the mentioned process. We deduce some qualitative results regarding the existence of such models in real life using mathematical analysis. The aforesaid analysis is based on some fixed points approaches. Additionally, some analysis devoted to stability is also derived for the proposed model. In addition, a numerical algorithms based on modified Euler method is constructed to simulate the results graphically.
On obtaining analytical soliton solutions of Drinfeld-Sokolov-Satsuma-Hirota equation via two efficient methods
Authors: Cakicioglu Hasan , Cinar Melih , Secer Aydin , Ozisik Muslum , Bayram Mustafa
Published: December 2023

In this work, we use the enhanced modified extended tanh method (eMETEM) and the unified Riccati equation expansion (UREEM) to find analytical solutions to the Drinfeld-Sokolov-Satsuma-Hirota equation (DSSH). The use of coupled nonlinear partial differential equations in the modeling of many physical phenomena, the origin of the Drinfeld-Sokolov-Satsuma-Hirota equation being the formation of the coupled system, and the fact that this model also constitutes a fundamental model in representing numerous physical events, primarily shallow water and coastal regions, have been the driving force behind the study. To visualize the obtained solutions, contour, two and three-dimensional plots are presented. The proposed methods have effectively generated a range of solitons, such as kink, singular, and periodic singular types. The graphic presentations complete the interpretation of the physical significance of the obtained kink and singular soliton types, and the interpretation of the obtained graphs within this framework. In this sense, the findings of the study will help to shape future research in this field.
Corrosion inhibition effects of organic compounds on carbon steel research progress: a visualization analysis based on CiteSpace
Authors: Jia Na , Wang Chunxin , Liu Jiuqing
Published: December 2023

This study systematically reviews the progress of research on the corrosion inhibition effects of organic compounds on carbon steel since 2002, using the CiteSpace bibliometric tool. Through the analysis of 2,264 articles from the WOS (Web of Science) and Scopus databases, our team delved into aspects such as annual publication volume, authors, institutions, countries and keywords which helped identify the current research focus in this field. In particular, the protective efficacy of organic compounds on carbon steel in acidic environments has been highlighted. It is evident that the integration of coating technology, the development of organic compound derivatives and the extraction of green organic compounds have emerged as new research hotspots in this field. This study not only comprehensively evaluates the means and methods of assessing the corrosion inhibition performance of new organic compounds but also further specifies the main directions for future research in this field. These include composite organic coatings, targeted development of new organic compounds, development and application of green organic compounds from plants and corrosion inhibition mechanisms of organic compounds on other metal materials. This study not only provides a thorough and in-depth review of the history and current status of this field but, more importantly, clarifies specific directions for future research in this area. The aim of this research is to provide strong theoretical support and practical guidance for subsequent researchers, promoting future development of this field.