bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparative analysis of 3D woven honeycomb-based aircrew helmet liners against Nomex and Aluminum alternatives
Authors: Singh Omender , Behera Bijoy Kumar , Thakur Nitin , Bahl Shashi
Published: May 2024

This study investigates the energy dissipation efficiency of an aircrew helmet liner developed using 3D woven honeycomb structural composites compared to different commercially available honeycomb liner materials such as Nomex, and Aluminium. In contrast to liners with discrete density differences, the use of a honeycomb-based liner reduces the concern about delamination, back face deformation and fracture propagation. The research involves comparing several parameters related to crashworthiness, such as specific energy absorption (SEA), crush force efficiency (CFE), and margin of safety, which are crucial for head protection and ensuring helmet injury tolerance. These parameters play a vital role in assessing the ability of different configurations of the honeycomb liner during impacts. Flatwise compression and dynamic impact tests were conducted to evaluate the helmet liner’s performance while maintaining consistency in the helmet shell component. Finite element analysis (FEA) and 3D x-ray Tomography techniques were utilized to analyse the back face deformation (BFD) at high-velocity impact and the internal damage resulting from impacts on the helmet liners, respectively. The results revealed that the 3D woven honeycomb liner configuration performs optimally in terms of energy absorption by demonstrating sufficient and balanced competency across these three critical factors. Additionally, the simulation result revealed that the 3D woven honeycomb liner exhibits wave propagation. This phenomenon enhances its energy absorption capacity and reduces back-face deformation attributed to its crushing behaviour. This research offers valuable insights for improving the performance of aircrew helmet liners, with a particular focus on utilizing 3D woven honeycomb liners featuring 3D woven solid structure to maintain exceptional structural integrity.
Inducing d
0 magnetism in new SrCl2 monolayer towards spintronic applications
Authors: On Vo Van , Ponce-Pérez R , Ha Chu Viet , Guerrero-Sanchez J , Hoat D M
Published: May 2024

Magnetism engineering in two-dimensional (2D) materials has been widely explored to make new spintronic materials. In this work, the doping (with alkali metals at Sr sublattice and with chalcogen atoms at Cl sublattice) method are proposed to induce significant d
0 magnetism in the non-magnetic SrCl2 monolayer. This 2D material is an indirect gap insulator with large band gap of 4.97(6.25) eV as obtained by PBE(HSE06) functional, exhibiting ionic character that is generated by the charge transfer from Sr atom to Cl atoms. The monolayer is significantly magnetized by doping with alkali metals, where a total magnetic moments between 0.90 and 1.00 μ

B
are obtained. Herein, Cl atoms closest to the doping site make main contribution to the system magnetism. Interestingly, the doped systems exhibit half-metallic behavior that is generated by semiconductor spin-up state and metallic spin-down state. On the other hand, the diluted magnetic semiconductor nature emerges in SrCl2 monolayer as a result of doping with chalcogen atoms. In these cases, total magnetic moment of 1.00 μ

B
is obtained, where magnetic properties are produced mainly by chalcogen impurities and Cl atoms below them. The electronic and magnetic properties of the doped systems are regulated mainly by the outermost p orbital of Cl and chalcogen atoms, and Sr-4d orbital that form mainly the conduction band. Upon further increasing the doping level of K and O atoms, the half-metallic or magnetic semiconductor natures are preserved. Results presented in this work may introduce new prospective 2D spintronic candidates for spintronic applications, which are derived from a non-magnetic SrCl2 monolayer via doping with d
0 atoms.
Computational study of lattice dynamics and mechanical properties of AlxIn1-xPySbzAs1-y-z/InP under the effect of composition
Authors: Alyami Mohammed , Alfrnwani O A , Othman Mazin Sh , Elkenany Elkenany B
Published: May 2024

For the first time, the composition dependence of pentanary AlInPSbAs alloy is described. The effect of composition on the polarity

(
∝

p

)
,

mechanical parameters have been calculated for the AlxIn1-xPySbzAs1-y-z alloy. The impact of composition on the internal strain parameter

(
ζ
)
,

bond-bending force constant (α), bond-stretching force constant (β), and sound velocity (v) has been reported. Results from experiments and the investigated properties of the new alloy show a high degree of agreement. In this work, the density function theory (DFT) and the empirical pseudo-potential approach (EPM) with the virtual crystal approximation (VCA) have been used. The outcomes are expected to be used in optoelectronic applications and in understanding the mechanical properties of AlxIn1-xPySbzAs1-y-z alloy.
Statistical analysis of the inverse power Zeghdoudi model: Estimation, simulation and modeling to engineering and environmental data
Authors: Elbatal Ibrahim , Hassan Amal S , Gemeay Ahmed M , Diab L S , Ben Ghorbal Anis , Elgarhy Mohammed
Published: May 2024

In this research, we investigate a brand-new two-parameter distribution as a modification of the power Zeghdoudi distribution (PZD). Using the inverse transformation technique on the PZD, the produced distribution is called the inverted PZD (IPZD). Its usefulness in producing symmetric and asymmetric probability density functions makes it the perfect choice for lifetime phenomenon modeling. It is also appropriate for a range of real data since the relevant hazard rate function has one of the following shapes: increasing, decreasing, reverse j-shape or upside-down shape. Mode, quantiles, moments, geometric mean, inverse moments, incomplete moments, distribution of order statistics, Lorenz, Bonferroni, and Zenga curves are a few of the significant characteristics and aspects explored in our study along with some graphical representations. Twelve effective estimating techniques are used to determine the distribution parameters of the IPZD. These include the Kolmogorov, least squares (LS), a maximum product of spacing, Anderson-Darling (AD), maximum likelihood, minimum absolute spacing distance, right-tail AD, minimum absolute spacing-log distance, weighted LS, left-tailed AD, Cramér-von Mises, AD left-tail second-order. A Monte Carlo simulation is used to examine the effectiveness of the obtained estimates. The visual representation and numerical results show that the maximum likelihood estimation strategy regularly beats the other methods in terms of accuracy when estimating the relevant parameters. The usefulness of the recommended distribution for modelling data is illustrated and displayed visually using two real data sets through comparisons with other distributions.
Hyperhydrodynamics: relativistic viscous fluids from hypermomentum
Authors: Iosifidis Damianos , Koivisto Tomi S.
Published: May 2024

We explore a new action formulation of hyperfluids, fluids with intrinsic hypermomentum. Brown's Lagrangian for a relativistic perfect fluid is generalised by incorporating the degrees of freedom encoded in the hypermomentum tensor, namely by including connection-matter couplings. Quite interestingly, generic hyperfluids are imperfect, since hypermomentum induces such effects as bulk and shear viscosities as well as heat fluxes. The various coefficients that appear in the first order expansion of hydrodynamics can now be deduced from a Lagrangian formulation, given a geometrical interpretation and a suggested microscopic description in terms of hypermomentum.
This connection between hypermomentum and dissipative fluids could shed new light on the physics of relativistic hydrodynamics.
The applicability of the new formalism is demonstrated by exact cosmological solutions.
The Sun and core-collapse supernovae are leading probes of the neutrino lifetime
Authors: Martínez-Miravé Pablo , Tamborra Irene , Tórtola Mariam
Published: May 2024

The large distances travelled by neutrinos emitted from the Sun and core-collapse supernovae together with the characteristic energy of such neutrinos provide ideal conditions to probe their lifetime, when the decay products evade detection. We investigate the prospects of probing invisible neutrino decay capitalising on the detection of solar and supernova neutrinos as well as the diffuse supernova neutrino background (DSNB) in the next-generation neutrino observatories Hyper-Kamiokande, DUNE, JUNO, DARWIN, and RES-NOVA.
We find that future solar neutrino data will be sensitive to values of the lifetime-to-mass ratio τ
1/m
1 and τ
2/m
2 of 𝒪(10-1–10-2) s/eV. From a core-collapse supernova explosion at 10 kpc, lifetime-to-mass ratios of the three mass eigenstates of 𝒪(105) s/eV could be tested. After 20 years of data taking, the DSNB would extend the sensitivity reach of τ
1/m
1 to 108 s/eV. These results promise an improvement of about 6–15 orders of magnitude on the values of the decay parameters with respect to existing limits.
Broken blue-tilted inflationary gravitational waves: a joint analysis of NANOGrav 15-year and BICEP/Keck 2018 data
Authors: Jiang Jun-Qian , Cai Yong , Ye Gen , Piao Yun-Song
Published: May 2024

Recently, the pulsar timing array (PTA) collaborations have
reported the evidence for a stochastic gravitational wave
background (SGWB) at nano-Hertz band. The spectrum of inflationary
gravitational wave (IGW) is unknown, which might exhibit different
power law at different frequency-bands, thus if the PTA signal is
primordial, it will be significant to explore the underlying
implications of current PTA and CMB data on IGW. In this Letter,
we perform a joint Markov Chain Monte Carlo analysis for a broken
power-law spectrum of IGW with the NANOGrav 15-year and BICEP/Keck
2018 data. It is found that though the bestfit spectral tilt of
IGW at PTA band is n
PTA
T = 2.42+0.32
-0.91,
at CMB band the bestfit is n
CMB
T 
= 0.55+0.37
-0.10 while a detectable amplitude of r with
 n
CMB
T ≃ 0 is still compatible. The
implication of our results for inflation is also discussed.
Analytical insights into constant-roll condition: extending the paradigm to non-canonical models
Authors: Mohammad Ahmadi S. , Ahmadi Nahid , Shokri Mehdi
Published: May 2024

In this work, we explore the prospect of generalizing the constant-roll condition in canonical inflationary model to non-canonical models. To find a natural generalization, we focus on three manifestations of this condition and construct constant-roll models corresponding to each manifestation. These models are not equivalent but reduce to the familiar constant-roll model in canonical limit. To showcase the applicability of our generalized mechanism, we examine a specific class of non-canonical models, which can be viewed as extensions of k/G inflation. In these models sound speed is constant. We conduct a comparative study, and with an analytical examination of the model, specify instances when our constant-roll conditions yield dissimilar outcomes and when they exhibit analogies. We also apply our findings to scrutinize another kinetically driven inflationary model with varying sound speed. We demonstrate that each of our constant-roll conditions leads to a unique set of solutions. Afterward, we construct a four-stage constant-roll kinetically driven inflation that complies with CMB constraints, it sustains for a sufficiently long period of time, and finally gracefully exits. In this model the spectrum of curvature perturbations is enhanced in a brief phase of non-slow-roll inflationary evolution. Employing numerical methods, we analyse this scenario to elucidate how altering the constant-roll condition impacts the power spectrum and the model's dynamics.
Shadow images of compact objects in beyond Horndeski theory
Authors: Huang Hyat , Kunz Jutta , Mitra Deeshani
Published: May 2024

A beyond Horndeski theory is considered that admits wormholes, black holes and naked singularities. In this theory the shadow images of the black holes and the exotic compact objects (ECOs), illuminated by an optically and geometrically thin disk, are investigated. The results show that the three kinds of objects cast unlike shadow images, in particular, because the different objects possess a different number of light rings. The different boundaries of the accretion disk also affect the images. This may provide further insight into the nature of the shadow images of massive compact objects.
The quest for CMB signatures of conformal cyclic cosmology
Authors: Bodnia Eve , Isenbaev Vlad , Colburn Kellan , Swearngin Joe , Bouwmeester Dirk
Published: May 2024

Circles of low-variance and Hawking points in the Cosmic Microwave Background (CMB), resulting from black hole mergers and black hole evaporation, respectively, in a previous cycle of the universe, have been predicted as possible evidence for the Conformal Cyclic Cosmology model (CCC) introduced by R. Penrose. We present a high-resolution search for such low-variance circles in the Planck and WMAP CMB data, and introduce HawkingNet, our machine learning open-source software based on a ResNet18 algorithm, to search for Hawking points in the CMB.
We find that spots consisting of a few unusually bright (high-temperature) or dark (low-temperature) pixels, erroneously lead to regions with many low-variance circles, and consequently sets of near-concentric low-variance circles, when applying the search criteria used in previous work [1]. After removing those spots from the data, no statistically significant low-variance circles can be found.
Concerning Hawking points, also no statistically significant evidence is found when using a Gaussian temperature amplitude model over ∼ 1° opening angle and after accounting for spots of unusual brightness.
That the unusual spots in the data are themselves remnants of Hawking points is not supported by low-variance and/or low-temperature circles around them.
The absence of such statistically-significant distinct features in the currently available CMB data does not disprove the CCC model, but implies that higher resolution CMB data and/or refined CCC based predictions are needed to pursue the search for CCC signatures further.
Self-interacting vectorial dark matter in a SM-like dark sector
Authors: Tran Van Que , Nguyen Thong T.Q. , Yuan Tzu-Chiang
Published: May 2024

A dark SU(2)
D
× U(1)
D
gauge-Higgs sector, an exact copy of the Standard Model (SM) one, is proposed. It is demonstrated that the
dark gauge bosons 𝒲(p,m), in analogous to the SM W
±,
can fulfill the role as a self-interacting vector dark matter candidate, solving the core versus cusp and missing satellites problems faced by the conventional paradigm of collisionless weakly interacting massive particle. Constraints from collider, astroparticle and cosmology on such a self-interacting vector dark matter candidate are scrutinized. Implications for the future searches of
 𝒲(p,m) in direct detection experiments are discussed.
The quantum corrected Schwarzschild black hole with a linear-quadratic GUP: a comprehensive evaluation
Authors: Barman Himangshu , Al-Badawi Ahmad , Jha Sohan Kumar , Rahaman Anisur
Published: May 2024

In this manuscript, we delve into an analytic and numerical probe of shadow with different accretion models, quasinormal modes, Hawking radiation, and gravitational lensing to study observational impacts of quantum effect introduced through linear-quadratic GUP(LQG). Our investigation reveals that the shadows of LQG-modified black holes are smaller and brighter than Schwarzschild black holes. To examine the impact of the quantum correction on the quasinormal mode, linear-quadratic GUP-modified black holes are explored under scalar and
electromagnetic field perturbation. Here, linear-quadratic GUP is
used to capture quantum corrections. It is observed that the
incorporation of quantum correction by linear-quadratic GUP alters
the singularity structure of the black hole. To compute the
quasinormal modes of this linear-quadratic GUP-inspired
quantum-corrected black holes, we compute the effective potential
generated under the perturbation of scalar and electromagnetic
field, and then we use the sixth-order WKB approach in conjunction
with the appropriate numerical analysis. We find that the greybody factor decreases with the GUP parameter α implying that the probability of transmission decreases with the GUP parameter. The total power emitted by LQG modified black hole is found to be greater than that emitted by Schwarzschild black hole. Finally, we study weak gravitational lensing and make a comparison with quadratic GUP and linear GUP-modified black holes.
GammaBayes: a Bayesian pipeline for dark matter detection with CTA
Authors: Pinchbeck Liam , Thrane Eric , Balazs Csaba
Published: May 2024

We present GammaBayes, a Bayesian Python package for dark matter detection with the Cherenkov Telescope Array (CTA).
GammaBayes takes as input the CTA measurements of gamma rays and a user-specified dark-matter particle model.
It outputs the posterior distribution for parameters of the dark-matter model including the velocity-averaged cross section for dark-matter self interactions 〈σv〉 and the dark-matter mass mχ
.
It also outputs the Bayesian evidence, which can be used for model selection.
We demonstrate GammaBayes using 525 hours of simulated data, corresponding to 108 observed gamma-ray events.
The vast majority of this simulated data consists of noise, but 100000 events arise from the annihilation of scalar singlet dark matter with mχ
= 1 TeV.
We recover the dark matter mass within a 95% credible interval of mχ
∼ 0.96–1.07 TeV.
Meanwhile, the velocity averaged cross section is constrained to 〈σv〉 ∼ 1.4–2.1 × 10-25 cm3 s-1 (95% credibility).
This is equivalent to measuring the number of dark-matter annihilation events to be NS
∼ 1.1-0.2
+0.2 × 105.
The no-signal hypothesis 〈σv〉 = 0 is ruled out with about 5σ credibility.
We discuss how GammaBayes can be extended to include more sophisticated signal and background models and the computational challenges that must be addressed to facilitate these upgrades.
The source code is publicly available here.
Smooth vs instant inflationary transitions: steepest growth re-examined and primordial black holes
Authors: Cole Philippa S. , Gow Andrew D. , Byrnes Christian T. , Patil Subodh P.
Published: May 2024

Primordial black holes (PBHs) can be produced by a range of mechanisms in the early
universe. A particular formation channel that connects PBHs with inflationary phenomenology
invokes enhanced primordial curvature perturbations at small scales. In this paper, we examine how
rapidly the background can transition between different values of the parameters of the Hubble
hierarchy in the context of single-clock inflation, which must ultimately derive from a consistent
derivative expansion for the background inflaton field. We discuss artefacts associated with
instant or very rapid transitions, and consider the impact on the steepest power spectrum growth
and the formation of PBHs. In particular, we highlight the robustness of the k
4 steepest growth
previously found for single-field inflation with conservatively smoothed transitions and limits on
how much the amplitude of the power spectrum can grow, and demonstrate that the PBH mass
distribution is sensitive to the artefacts, which go away when the transitions are smoothed. We
also show that the mass distribution is relatively insensitive to the steepness of the growth and
subsequent decay of the power spectrum, depending primarily on the peak amplitude and the presence
of any plateaus that last more than an e-fold. The shape of the power spectrum can of course be
constrained by other tracers, and so understanding the physical limitations on its shape remains a
pertinent question.
Observational feasibility of 4D Einstein-Gauss-Bonnet cosmology: bouncing and non-bouncing universes
Authors: Khodabakhshi H. , Farhang M. , Lü H.
Published: May 2024

This paper analyzes the possibility of bouncing and non-bouncing universes in the framework of four-dimensional Einstein-Gauss-Bonnet (4D-EGB) gravity,
corresponding respectively to negative and positive coupling constants λ of the Gauss-Bonnet term. We also use the Horndeski-type scalar-tensor theory to assess the role of a scalar charge C as a geometrical contribution to the radiation in the Universe.
We modify the expansion history of the universe to allow for modifications induced by the 4D-EGB gravity.
Using Planck measurements of the cosmic microwave background anisotropies as well as various datasets of baryonic acoustic oscillations, we set the upper bounds λ ≤ 10-16(km/s/Mpc)-2 and λ ≤ 10-30(km/s/Mpc)-2 for the non-bouncing and bouncing scenarios.
The upper limit in the latter case is mainly driven by the requirement to conservatively respect the thermal history at energy scales of the standard model of particle physics.
We also find that the contribution of the geometrical radiation-like term of the model cannot exceed 10% of the current radiation in the Universe. The possibility of an early inflationary phase produced by a single scalar field is also studied and found to be feasible in both bouncing and non-bouncing scenarios.
This study shows the feasibility of a bouncing universe, even with a normal matter sector, in the 4D-EGB gravity. More theoretical investigation is required to further explore possible observational predictions of the model that can distinguish between general relativity and 4D-EGB gravity.
Decoherence out of fire: purity loss in expanding and contracting universes
Authors: Colas Thomas , de Rham Claudia , Kaplanek Greg
Published: May 2024

We investigate quantum decoherence in a class of models which interpolates between expanding (inflation) and contracting (ekpyrosis) scenarios. For the cases which result in a scale-invariant power spectrum, we find that ekpyrotic universes lead to complete decoherence of the curvature perturbation before the bounce. This is in stark contrast to the inflationary case, where recoherence has been previously observed in some situations. Although the purity can be computed for couplings of all sizes, we also study the purity perturbatively and observe that late-time (secular growth) breakdown of perturbation theory often occurs in these cases. Instead, we establish a simple yet powerful late-time purity resummation which captures the exact evolution to a remarkable level, while maintaining analytical control. We conclude that the cosmological background plays a crucial role in the decoupling of the heavy fields during inflation and alternatives.
Nonlinear gravitational waves in Horndeski gravity: scalar pulse and memories
Authors: Achour Jibril Ben , Gorji Mohammad Ali , Roussille Hugo
Published: May 2024

We present and analyze a new non-perturbative radiative solution of Horndeski gravity. This exact solution is constructed by a disformal mapping of a seed solution of the shift-symmetric Einstein-Scalar system belonging to the Robinson-Trautman geometry describing the gravitational radiation emitted by a time-dependent scalar monopole. After analyzing in detail the properties of the seed, we show that while the general relativity solution allows for shear-free parallel transported null frames, the disformed solution can only admit parallel transported null frames with a non-vanishing shear.
This result shows that, at the nonlinear level, the scalar-tensor mixing descending from the higher-order terms in Horndeski dynamics can generate shear out of a pure scalar monopole. We further confirm this analysis by identifying the spin-0 and spin-2 polarizations in the disformed solution using the Penrose limit of our radiative solution.
Finally, we compute the geodesic motion and the memory effects experienced by two null test particles with vanishing initial relative velocity after the passage of the pulse.
This exact radiative solution offers a simple framework to witness nonlinear consequences of the scalar-tensor mixing in higher-order scalar-tensor theories.
Observing gravitational waves with solar system astrometry
Authors: Mentasti G. , Contaldi C.R.
Published: May 2024

The subtle influence of gravitational waves on the apparent positioning of celestial bodies offers novel observational windows [1,2,3,4]. We calculate the expected astrometric signal induced by an isotropic Stochastic Gravitational Wave Background (SGWB) in the short distance limit. Our focus is on the resultant proper motion of Solar System objects, a signal on the same time scales addressed by Pulsar Timing Arrays (PTA). We derive the corresponding astrometric deflection patterns, finding that they manifest as distinctive dipole and quadrupole correlations or, in some cases, may not be present. Our analysis encompasses both Einsteinian and non-Einsteinian polarisations. We estimate the upper limits for the amplitude of SGWBs that could be obtained by tracking the proper motions of large numbers of solar system objects such as asteroids. We find that for SGWBs with negative spectral indices, such as that generated by Super Massive Black Hole Binaries (SMBHB), the constraints from these observations could rival those from PTAs. With the Gaia satellite and the Vera C. Rubin Observatory poised to track an extensive sample of asteroids — ranging from 𝒪(105) to 𝒪(106), we highlight the significant future potential for similar surveys to contribute to our understanding of the SGWB.
Exploring antisymmetric tensor effects on black hole shadows and quasinormal frequencies
Authors: Araújo Filho A.A. , Reis J.A.A.S. , Hassanabadi H.
Published: May 2024

This study explores the impact of antisymmetric tensor effects on spherically symmetric black holes, investigating photon spheres, shadows, emission rate and quasinormal frequencies in relation to a parameter which triggers the Lorentz symmetry breaking. We examine these configurations without and with the presence of a cosmological constant. In the first scenario, the Lorentz violation parameter, denoted as λ, plays a pivotal role in reducing both the photon sphere and the shadow radius, while also leading to a damping effect on quasinormal frequencies. Conversely, in the second scenario, as the values of the cosmological constant (Λ) increase, we observe an expansion in the shadow radius. Also, we provide the constraints of the shadows based on the analysis observational data obtained from the Event Horizon Telescope (EHT) focusing on Sagittarius A*
shadow images. Additionally, with the increasing Λ, the associated gravitational wave frequencies exhibit reduced damping modes.
Measurement-free mediated semi-quantum key distribution protocol based on single-particle states
Authors: Zhou Shun , Xie Qi-Ming , Zhou Nan-Run
Published: May 2024

A novel measurement-free mediated semi-quantum key distribution (MSQKD) protocol is proposed based on single-particle states. It enables two classical users to establish a secret key with the assistance of a third party. This protocol simplifies the third party’s role to solely generating qubits in X-basis and conducting Bell measurements. A distinctive feature of this protocol is the efficient grouping and reordering of qubits by the classical users with a minimum of three delay lines. Security analyses demonstrate that the protocol can withstand various attack strategies, including collective attack, measurement attack, fake state attack, and modification attack. The noise tolerance is given by deriving a lower bound of the protocol’s key rate in the asymptotic scenario. Simulations on the IBM Quantum Experience platform are conducted to illustrate the feasibility of this protocol. Compared with existing MSQKD protocols, the proposed protocol consumes fewer quantum resources and achieves a qubit efficiency of 1/8.
Topological superconductors with spin-triplet pairings and Majorana Fermi arcs
Authors: Huang 黄 Shi 石 , Luo 罗 Xi 熙
Published: May 2024

We construct a three-dimensional topological superconductor Bogoliubov–de Gennes (BdG) Hamiltonian with the normal state being a three-dimensional topological insulator. By introducing inter-orbital spin-triplet pairings term Δ
3, there are topological Majorana nodes in the bulk and they are connected by Majorana Fermi arcs on the surface, similar to the case of Weyl semimetal. Furthermore, by adding an inversion-breaking term to the normal state, momentum-independent pairing terms with different parities can coexist in the BdG Hamiltonian, which creates more Majorana modes similar to Andreev bound states and a richer phase diagram.
An integrable generalization of the Fokas–Lenells equation: Darboux transformation, reduction and explicit soliton solutions
Authors: Wei 魏 Jiao 姣 , Geng 耿 Xianguo 献国 , Wang 王 Xin 鑫
Published: May 2024

Under investigation is an integrable generalization of the Fokas–Lenells equation, which can be derived from the negative power flow of a 2 × 2 matrix spectral problem with three potentials. Based on the gauge transformation of the matrix spectral problem, one kind of Darboux transformation with multi-parameters for the three-component coupled Fokas–Lenells system is constructed. As a reduction, the N-fold Darboux transformation for the generalized Fokas–Lenells equation is obtained, from which the N-soliton solution in a compact Vandermonde-like determinant form is given. Particularly, the explicit one- and two-soliton solutions are presented and their dynamical behaviors are shown graphically.
Design and control of jumping microrobots with torque reversal latches
Authors: Skowronski Nolan , Malek Pour Mohammadamin , Singh Shashwat , Longo Sarah J , St Pierre Ryan
Published: May 2024

Jumping microrobots and insects power their impressive leaps through systems of springs and latches. Using springs and latches, rather than motors or muscles, as actuators to power jumps imposes new challenges on controlling the performance of the jump. In this paper, we show how tuning the motor and spring relative to one another in a torque reversal latch can lead to an ability to control jump output, producing either tuneable (variable) or stereotyped jumps. We develop and utilize a simple mathematical model to explore the underlying design, dynamics, and control of a torque reversal mechanism, provides the opportunity to achieve different outcomes through the interaction between geometry, spring properties, and motor voltage. We relate system design and control parameters to performance to guide the design of torque reversal mechanisms for either variable or stereotyped jump performance. We then build a small (356 mg) microrobot and characterize the constituent components (e.g. motor and spring). Through tuning the actuator and spring relative to the geometry of the torque reversal mechanism, we demonstrate that we can achieve jumping microrobots that both jump with different take-off velocities given the actuator input (variable jumping), and those that jump with nearly the same take-off velocity with actuator input (stereotyped jumping). The coupling between spring characteristics and geometry in this system has benefits for resource-limited microrobots, and our work highlights design combinations that have synergistic impacts on output, compared to others that constrain it. This work will guide new design principles for enabling control in resource-limited jumping microrobots.
3D-printed porous tantalum artificial bone scaffolds: fabrication, properties, and applications
Authors: Yu Haiyu , Xu Minghao , Duan Qida , Li Yada , Liu Yuchen , Song Liqun , Cheng Liangliang , Ying Jiawei , Zhao Dewei
Published: May 2024

Porous tantalum scaffolds offer a high degree of biocompatibility and have a low friction coefficient. In addition, their biomimetic porous structure and mechanical properties, which closely resemble human bone tissue, make them a popular area of research in the field of bone defect repair. With the rapid advancement of additive manufacturing, 3D-printed porous tantalum scaffolds have increasingly emerged in recent years, offering exceptional design flexibility, as well as facilitating the fabrication of intricate geometries and complex pore structures that similar to human anatomy. This review provides a comprehensive description of the techniques, procedures, and specific parameters involved in the 3D printing of porous tantalum scaffolds. Concurrently, the review provides a summary of the mechanical properties, osteogenesis and antibacterial properties of porous tantalum scaffolds. The use of surface modification techniques and the drug carriers can enhance the characteristics of porous tantalum scaffolds. Accordingly, the review discusses the application of these porous tantalum materials in clinical settings. Multiple studies have demonstrated that 3D-printed porous tantalum scaffolds exhibit exceptional corrosion resistance, biocompatibility, and osteogenic properties. As a result, they are considered highly suitable biomaterials for repairing bone defects. Despite the rapid development of 3D-printed porous tantalum scaffolds, they still encounter challenges and issues when used as bone defect implants in clinical applications. Ultimately, a concise overview of the primary challenges faced by 3D-printed porous tantalum scaffolds is offered, and corresponding insights to promote further exploration and advancement in this domain are presented.
Organoid bioinks: construction and application
Authors: Wang Fuxiao , Song Peiran , Wang Jian , Wang Sicheng , Liu Yuanyuan , Bai Long , Su Jiacan
Published: May 2024

Organoids have emerged as crucial platforms in tissue engineering and regenerative medicine but confront challenges in faithfully mimicking native tissue structures and functions. Bioprinting technologies offer a significant advancement, especially when combined with organoid bioinks-engineered formulations designed to encapsulate both the architectural and functional elements of specific tissues. This review provides a rigorous, focused examination of the evolution and impact of organoid bioprinting. It emphasizes the role of organoid bioinks that integrate key cellular components and microenvironmental cues to more accurately replicate native tissue complexity. Furthermore, this review anticipates a transformative landscape invigorated by the integration of artificial intelligence with bioprinting techniques. Such fusion promises to refine organoid bioink formulations and optimize bioprinting parameters, thus catalyzing unprecedented advancements in regenerative medicine. In summary, this review accentuates the pivotal role and transformative potential of organoid bioinks and bioprinting in advancing regenerative therapies, deepening our understanding of organ development, and clarifying disease mechanisms.
Functionally graded hydrogels with opposing biochemical cues for osteochondral tissue engineering
Authors: Mahajan Aman , Zaidi Zahra Sifat , Shukla Amit , Saxena Rakshita , Katti Dhirendra S
Published: May 2024

Osteochondral tissue (OC) repair remains a significant challenge in the field of musculoskeletal tissue engineering. OC tissue displays a gradient structure characterized by variations in both cell types and extracellular matrix components, from cartilage to the subchondral bone. These functional gradients observed in the native tissue have been replicated to engineer OC tissue in vitro. While diverse fabrication methods have been employed to create these microenvironments, emulating the natural gradients and effective regeneration of the tissue continues to present a significant challenge. In this study, we present the design and development of CMC-silk interpenetrating (IPN) hydrogel with opposing dual biochemical gradients similar to native tissue with the aim to regenerate the complete OC unit. The gradients of biochemical cues were generated using an in-house-built extrusion system. Firstly, we fabricated a hydrogel that exhibits a smooth transition of sulfated carboxymethyl cellulose (sCMC) and TGF-β1 (SCT gradient hydrogel) from the upper to the lower region of the IPN hydrogel to regenerate the cartilage layer. Secondly, a hydrogel with a hydroxyapatite (HAp) gradient (HAp gradient hydrogel) from the lower to the upper region was fabricated to facilitate the regeneration of the subchondral bone layer. Subsequently, we developed a dual biochemical gradient hydrogel with a smooth transition of sCMC + TGF-β1 and HAp gradients in opposing directions, along with a blend of both biochemical cues in the middle. The results showed that the dual biochemical gradient hydrogels with biochemical cues corresponding to the three zones (i.e. cartilage, interface and bone) of the OC tissue led to differentiation of bone-marrow-derived mesenchymal stem cells to zone-specific lineages, thereby demonstrating their efficacy in directing the fate of progenitor cells. In summary, our study provided a simple and innovative method for incorporating gradients of biochemical cues into hydrogels. The gradients of biochemical cues spatially guided the differentiation of stem cells and facilitated tissue growth, which would eventually lead to the regeneration of the entire OC tissue with a smooth transition from cartilage (soft) to bone (hard) tissues. This promising approach is translatable and has the potential to generate numerous biochemical and biophysical gradients for regeneration of other interface tissues, such as tendon-to-muscle and ligament-to-bone.
Maximization of uricase production in a column bioreactor through response surface methodology-based optimization
Authors: Taghizadeh Mohammad Hossein , Khajeh Khosro , Nasirpour Niloofar , Mousavi Seyyed Mohammad
Published: May 2024

Uricase (EC 1.7.3.3) is an oxidoreductase enzyme that is widely exploited for diagnostic and treatment purposes in medicine. This study focuses on producing recombinant uricase from E. coli BL21 in a bubble column bioreactor (BCB) and finding the optimal conditions for maximum uricase activity. The three most effective variables on uricase activity were selected through the Plackett–Burman design from eight different variables and were further optimized by the central composite design of the response surface methodology (RSM). The selected variables included the inoculum size (%v/v), isopropyl β-d-1-thiogalactopyranoside (IPTG) concentration (mM) and the initial pH of the culture medium. The activity of uricase, the final optical density at 600 nm wavelength (OD600) and the final pH were considered as the responses of this optimization and were modeled. As a result, activity of 5.84 U·ml−1 and a final OD600 of 3.42 were obtained at optimum conditions of 3% v/v inoculum size, an IPTG concentration of 0.54 mM and a pH of 6.0. By purifying the obtained enzyme using a Ni-NTA agarose affinity chromatography column, 165 ± 1.5 mg uricase was obtained from a 600 ml cell culture. The results of this study show that BCBs can be a highly effective option for large-scale uricase production.
Preparation method and applicability evaluation of 3D printing alumina ceramic artificial coarse aggregate
Authors: Zhang Yake , Li Xi , Hu Kaikai , Qian Guoping , Gong Xiangbing , Yu Huanan
Published: May 2024

The particle size and morphology of crushed stones impact their macroscopic mechanical and physical properties, which has become a hot topic in the study of road and geotechnical engineering. However, some reported studies fail to control the particle morphology as the only independent variable. This paper presented a new method to print artificial aggregates based on 3D printing technology of particles. The applicability of the new method was verified with uniaxial compression and dynamic modulus tests of asphalt mixtures formed by the printing aggregates. Results showed that the printing aggregates earned similar physical properties to real coarse when sintered at 1400 °C with alumina ceramic powder and CuO: TiO2 a 1:2 additive in mass. Besides, the gross volume density, compressive strength, and shrinkage of the printing aggregates show a similar trend of increasing and then decreasing with the increase of additives. The optimal mass percentage of additives was obtained to be 5%. Mechanical tests indicated that the mechanical indexes of the asphalt mixtures formed with the two types of coarse aggregates were similar, while the results of the specimens formed with artificial coarse aggregates showed less dispersion. The stability of test results was significantly improved for different asphalt mixture specimens prepared with 3D printed coarse aggregate. This provides a basic method for further research on the multi-scale properties of particle material.
Model predictive control (MPC) applied to a simplified model, magnetic nanoparticle hyperthermia (MNPH) treatment process
Authors: Abu-Ayyad Ma’Moun , Lad Yash Sharad , Aguilar Dario , Karami Kiana , Attaluri Anilchandra
Published: May 2024

Magnetic nanoparticle hyperthermia (MNPH) has emerged as a promising cancer treatment that complements conventional ionizing radiation and chemotherapy. MNPH involves injecting iron-oxide nanoparticles into the tumor and exposing it to an alternating magnetic field (AMF). Iron oxide nanoparticles produce heat when exposed to radiofrequency AMF due to hysteresis loss. Minimizing the non-specific heating in human tissues caused by exposure to AMF is crucial. A pulse-width-modulated AMF has been shown to minimize eddy-current heating in superficial tissues. This project developed a control strategy based on a simplified mathematical model in MATLAB SIMULINK® to minimize eddy current heating while maintaining a therapeutic temperature in the tumor. A minimum tumor temperature of 43 [°C] is required for at least 30 [min] for effective hyperthermia, while maintaining the surrounding healthy tissues below 39 [°C]. A model predictive control (MPC) algorithm was used to reach the target temperature within approximately 100 [s]. As a constrained MPC approach, a maximum AMF amplitude of 36 [kA/m] and increment of 5 [kA/m/s] were applied. MPC utilized the AMF amplitude as an input and incorporated the open-loop response of the eddy current heating in its dynamic matrix. A conventional proportional integral (PI) controller was implemented and compared with the MPC performance. The results showed that MPC had a faster response (30 [s]) with minimal overshoot (1.4 [%]) than PI controller (115 [s] and 5.7 [%]) response. In addition, the MPC method performed better than the structured PI controller in its ability to handle constraints and changes in process parameters.
RFPID: development and 3D-printing of a female physical phantom for whole-body counter
Authors: Andrade E M R , Paixão L , Mendes B M , Fonseca T C F
Published: May 2024

Whole-body counters (WBC) are used in internal dosimetry for in vivo monitoring in radiation protection. The calibration processes of a WBC set-up include the measurement of a physical phantom filled with a certificate radioactive source that usually is referred to a standard set of individuals determined by the International Commission on Radiological Protection (ICRP). The aim of this study was to develop an anthropomorphic and anthropometric female physical phantom for the calibration of the WBC systems. The reference female computational phantom of the ICRP, now called RFPID (Reference Female Phantom for Internal Dosimetry) was printed using PLA filament and with an empty interior. The goal is to use the RFPID to reduce the uncertainties associated with in vivo monitoring system. The images which generated the phantom were manipulated using ImageJ®, Amide®, GIMP® and the 3D Slicer® software. RFPID was split into several parts and printed using a 3D printer in order to print the whole-body phantom. The newly printed physical phantom RFPID was successfully fabricated, and it is suitable to mimic human tissue, anatomically similar to a human body i.e., size, shape, material composition, and density.
Comparing discriminating abilities of evaluation metrics in link prediction
Authors: Jiao Xinshan , Wan Shuyan , Liu Qian , Bi Yilin , Lee Yan-Li , Xu En , Hao Dong , Zhou Tao
Published: May 2024

Link prediction aims to predict the potential existence of links between two unconnected nodes within a network based on the known topological characteristics. Evaluation metrics are used to assess the effectiveness of algorithms in link prediction. The discriminating ability of these evaluation metrics is vitally important for accurately evaluating link prediction algorithms. In this study, we propose an artificial network model, based on which one can adjust a single parameter to monotonically and continuously turn the prediction accuracy of the specifically designed link prediction algorithm. Building upon this foundation, we show a framework to depict the effectiveness of evaluating metrics by focusing on their discriminating ability. Specifically, a quantitative comparison in the abilities of correctly discerning varying prediction accuracies was conducted encompassing nine evaluation metrics: Precision, Recall, F1-Measure, Matthews correlation coefficient, balanced precision, the area under the receiver operating characteristic curve (AUC), the area under the precision-recall curve (AUPR), normalized discounted cumulative gain (NDCG), and the area under the magnified receiver operating characteristic. The results indicate that the discriminating abilities of the three metrics, AUC, AUPR, and NDCG, are significantly higher than those of other metrics.
Drosophila Nhe2 overexpression induces autophagic cell death
Authors: Peralta Jobelle , DuPriest Blake , Orozco Daniel , Pacheco Juan Reyna , Martins Laura , Soriano Rachel Ann , Wong Alan , Wong Ramy , Grillo-Hill Bree
Published: May 2024

Autophagy is a conserved catabolic process where double membrane-bound structures form around macromolecules or organelles targeted for degradation. Autophagosomes fuse with lysosomes to facilitate degradation and macromolecule recycling for homeostasis or growth in a cell autonomous manner. In cancer cells, autophagy is often up-regulated and helps cancer cells survive nutrient deprivation and stressful growth conditions. Here, we propose that the increased intracellular pH (pHi) common to cancer cells is sufficient to induce autophagic cell death. We previously developed tools to increase pHi in the Drosophila eye via overexpression of DNhe2, resulting in aberrant patterning and reduced tissue size. We examined fly eyes at earlier stages of development and found fewer interommatidial cells. We next tested whether this decrease in cell number was due to increased cell death. We found that the DNhe2-induced cell death was caspase independent, which is inconsistent with apoptosis. However, this cell death required autophagy genes, which supports autophagy as the mode of cell death. We also found that expression of molecular markers supports increased autophagy. Together, our findings suggest new roles for ion transport proteins in regulating conserved, critical developmental processes and provide evidence for new paradigms in growth control.
Litigating Climate Change in the Global South
Authors: Lin Jolene , Peel Jacqueline
Published: May 2024

This introductory chapter outlines the approach and structure of the book. It explains how the book’s study of Global South climate litigation has been scoped and undertaken. This includes discussion of: (1) the international law and governance context in which climate litigation is occurring and how this case law might contribute to global climate governance; (2) the understanding of the ‘Global South’ adopted in the book and why this terminology has been used; (3) how the book has approached the definition of climate litigation; and (4) the application of this definition in the book’s methodology for the selection and analysis of Global South cases.