Article
Chemistry, Physical
Xinyue Wang, Huijie Guo, Dawei Kang, Tonu Pullerits, Peng Song
Summary: The electric-field-dependent charge-separation dynamics of non-fullerene acceptors D/A heterojunctions were simulated using Marcus theory. The excited-state characteristics on the D/A interface showed differences under different electric-field intensities, providing microscopic details of the atomic-level non-fullerene D/A interface. The reorganization energy was found to mainly determine the charge-transfer rate, which showed variation depending on the electric-field intensity and was consistent with the Marcus inverted region. The charge separation exhibited significant advantages and the trifurcated structure of the molecule provided multiple charge transfer paths for charge separation.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Engineering, Chemical
Yuanxin Zhai, Dan Bai, Yifan Wang, Yaozhong Zhang, Yongchao Qi, Xiaopeng Qiu, Yi-fan Wang, Yi Xuan Wang, Xing Zheng
Summary: This study compared the adsorption behaviors of typical organics and the fouling effect on a polyvinylidene fluoride membrane surface under different Na+ concentrations, and investigated the impact of structural variation on these behaviors. The results indicate that the impact of Na+ on organics depends on their charge and structure. Different organics exhibited different changes in interaction force and relative irreversibility with the membrane at different Na+ concentrations.
Article
Astronomy & Astrophysics
Gadi Afek, Fernando Monteiro, Jiaxiang Wang, Benjamin Siegel, Sumita Ghosh, David C. Moore
Summary: mCPs, hypothesized particles with a fraction of the charge of the electron, are the subject of a sensitive search in this study that aims to improve detection of their abundance in matter. The research covers a wide range of masses and charges where mCPs could form stable bound states with matter, filling a gap in parameter space previously unexplored by traditional methods.
Article
Physics, Multidisciplinary
Pedro V. P. Cunha, Carlos Herdeiro, Eugen Radu, Nicolas Sanchis-Gual
Summary: Ultracompact objects with light rings but without an event horizon can mimic black holes in their strong gravity phenomenology. Through numerical simulations and the introduction of a novel technique, we confirm the instability triggered by the light rings and identify two possible outcomes: migration to nonultracompact configurations or collapse to black holes.
PHYSICAL REVIEW LETTERS
(2023)
Article
Astronomy & Astrophysics
Marie Cassing, Alexander Brisebois, Muhammad Azeem, Juergen Schaffner-Bielich
Summary: The generic properties of compact objects made of two different fluids of dark matter are studied. Compact objects with a core-shell structure and mixed dark matter components are investigated. The results show novel features in the mass-radius relations for combined dark matter compact objects, distinguishing them from compact objects with a single dark matter fluid and compact stars made of ordinary baryonic matter.
ASTROPHYSICAL JOURNAL
(2023)
Article
Physics, Multidisciplinary
Aisha Rashid, M. Farasat Shamir, Iffat Fayyaz
Summary: This study presents a set of exact spherically symmetric solutions based on the f (R, T) modified theory of gravity to describe the interior of a relativistic star. The metric potentials are achieved by using a Conformal Killing Vectors (CKV) and Bardeen's model for boundary conditions. Matching conditions are employed to obtain free parameters for the physical analysis. The study investigates several physically valid attributes and finds that the derived compact star solutions are physically acceptable and authentic in the presence of charge with conformal motion.
FORTSCHRITTE DER PHYSIK-PROGRESS OF PHYSICS
(2023)
Article
Astronomy & Astrophysics
Ruipeng Lu, Han Yue, Xiaoyu Lai, Weihua Wang, Shenjian Zhang, Renxin Xu
Summary: In this study, the elastic deformation theories of earthquakes were applied to investigate the starquake problems of pulsars. The stress loading associated with rotation deceleration was computed, and the optimal type of starquakes at various locations was determined. The results showed that starquakes in the strangeon star model can explain the observed glitch amplitude, although the required magnitude is much larger than earthquakes on Earth.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Jim Fuller, Wenbin Lu
Summary: The angular momentum content of massive stellar cores is important for determining the rotation rates of neutron stars and black holes. Prior work has shown that low-mass stars rotate slower than predicted, necessitating revised models. This study applies an updated angular momentum transport model to massive helium stars in close binaries and explores its implications for various astrophysical phenomena. The models are consistent with observed rates and energetics, except for broad-lined Ic supernovae.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Engineering, Chemical
Donghai Yang, Huayao Sun, Mofan Li, Qing Li, Xuedong Gao, Chaohui Chen, Limin He
Summary: This study investigates the coalescence behavior under a DC electric field through experimental and numerical methods. The results show that increasing electric field strength and droplet diameter lead to the formation of secondary droplets. The electric field strength suppresses the expansion and vertical collapse of the liquid bridge, while the increase in droplet diameter affects the shrinkage of the liquid bridge and prevents vertical collapse.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Engineering, Chemical
Jingwen Lu, Kui Geng, Qiushuang Zhang, Junwen Yao, Lin Cui, Yong Dong
Summary: Increasing the induction electrode voltage and atomization pressure, as well as reducing Cl- concentration, were found to improve the agglomeration efficiency of fine particles. Under specific conditions, the agglomeration efficiency of fine particles significantly increased after evaporation of charged droplets.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Astronomy & Astrophysics
Lukasz Bratek, Joanna Jalocha, Marek Kutschera
Summary: This paper provides some systematic remarks on the spherically symmetric approximation used in describing compact stars with gravitationally strong magnetic fields, including the issues of mass definition considering electromagnetic mass contribution and the problem of effective magnetic charges associated with the approximation method. Two simple models of compact stars with ultrastrong magnetic fields ranging from 1017 to 1018 Gs are studied in the limit of exact spherical symmetry, which is the limit of the considered spherical approximations. The characteristics of magnetized MIT-bag strange quark star show scaling with the bag constant, indicating a scaling symmetry of the equations of stellar structure. This model is compared with a neutron star model described by the UV14 + TNI equation of state. At the strongest fields, the modeled star masses exceed values normally expected for compact stars and are more similar to those of black holes or models with exotic equations of state. Based on the example of a neutron star considered in this paper, it seems that excessively strong magnetic fields may render models of compact stars radially unstable.
Article
Chemistry, Physical
Shuangliang Zhao, Zhiying Song, Leying Qing, Jingmin Zhou, Chongzhi Qiao
Summary: This study investigates the surface wettability effect on the energy density and power density of electrochemical supercapacitors using density functional theory. The results show that adjusting the surface wettability can increase energy density but decrease power density, and optimal energy density can be achieved with highly confined pores. Increasing ion concentration and surface voltage can enhance both energy density and power density of the supercapacitors.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Astronomy & Astrophysics
A. L. Patel, J. S. Urquhart, A. Y. Yang, T. J. T. Moore, K. M. Menten, M. A. Thompson, M. G. Hoare, T. Irabor, S. L. Breen, M. D. Smith
Summary: This study uses archival high-frequency continuum data to expand the search for Hypercompact H ii regions and determine the conditions at which they appear. The researchers used 23 GHz continuum data towards methanol masers and identified 49 H ii regions, 47 of which are embedded in dense clumps. They also identified 13 methanol maser sites that are coincident with radio sources with a steep positive spectral index, suggesting they are good HC H ii region candidates.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
David Sweeney, Peter Tuthill, Sanjib Sharma, Ryosuke Hirai
Summary: This article discusses the expected distribution of neutron stars and black holes in the Milky Way galaxy, highlighting their fundamental differences from the visible galaxy. The distribution is influenced by the evolving structure of the galaxy itself and the natal kick received by the remnants during their supernova birth. The findings have implications for understanding the evolution of the galaxy and for observing the characteristics of neutron stars and black holes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Physics, Multidisciplinary
Simranjeet Kaur, S. K. Maurya, Sacheendra Shukla, Riju Nag
Summary: In this work, a non-singular spherically symmetric charged anisotropic stellar object is obtained in the context of f(R, T)-gravity theory. The field equations are derived and solved by using the MIT Bag model equation of state and Tolman-Kuchowicz ansatz. Various physical properties and stability of the proposed model are investigated.
CHINESE JOURNAL OF PHYSICS
(2022)
Article
Astronomy & Astrophysics
B. C. Paul, A. Chanda, A. Beesham, S. D. Maharaj
Summary: This article investigates cosmological models in f(R) modified gravity with coupled Gauss-Bonnet terms. The evolution of the universe is obtained using numerical techniques, and the presence of dark energy and the oscillation properties of parameters are studied. The results show that under certain interaction strengths, the cosmological parameters can exhibit non-singular oscillation characteristics, and the gravitational coupling constant plays an important role. Additionally, in the presence of interactions, energy from the radiation sector cannot flow to other sectors.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Physics, Particles & Fields
Noeleen Naidoo, Sunil D. Maharaj, Keshlan S. Govinder
Summary: The relationship between radiating stars and Riccati equations in general relativity is examined, considering a general matter distribution including the electromagnetic field and the cosmological constant. A generalized transformation for describing the gravitational potentials of a spherically symmetric relativistic gravitating fluid is introduced, leading to a new Riccati equation at the surface of the radiating star. Exact solutions satisfying the boundary condition are obtained, and the gravitational potentials are explicitly given. Some consistency conditions are reduced to Bernoulli equations, allowing for exact solutions. It is also shown that reducing the order enables the boundary condition to be expressed as a first order equation using the generalized transformation. Solutions obtained using the generalized transformation also satisfy a linear equation of state.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Alberto K. Mathias, Sunil D. Maharaj, Jefta M. Sunzu, Jason M. Mkenyeleye
Summary: This article discusses the exact solutions to the Einstein field equations for class I spacetime symmetry in relativistic stars, generating a model with astrophysical significance. The model satisfies various physical properties.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2022)
Article
Physics, Multidisciplinary
Shobhit Giri, Hemwati Nandan, Lokesh Kumar Joshi, Sunil D. Maharaj
Summary: This paper investigates the dynamics of test particles and the stability of circular geodesics in a non-commutative geometry-inspired Schwarzschild black hole spacetime. The study analyzes the Lyapunov exponent and stability of equatorial circular geodesics for both massive and massless test particles, considering different values of the non-commutative parameter (alpha). The instability of null circular orbits is also discussed, and the quasinormal modes for massless scalar field perturbation are evaluated and visualized by relating the angular frequency and Lyapunov exponent.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Mathematical
Chevarra Hansraj, Rituparno Goswami, Sunil D. D. Maharaj
Summary: In this paper, we study conformally symmetric generalized Vaidya spacetimes with composite null dust and null string matter distribution using a decomposition method. Our analysis reveals that the geometric variables related to both time-like and preferred space-like congruences are completely determined by the conformal vector and conformal factor. This uniqueness arises from the specific matter distribution of the generalized Vaidya configuration. Additionally, we demonstrate that a proper conformal Killing vector cannot be admitted in the case of pure null dust (or Vaidya) spacetime.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2023)
Article
Physics, Multidisciplinary
Noeleen Naidoo, Sunil D. Maharaj, Keshlan S. Govinder
Summary: A model of a radiating star undergoing gravitational collapse is constructed by studying the boundary condition and equation of state. New classes of exact solutions with acceleration, expansion and shear in the presence of the cosmological constant are obtained. The range of the equation of state parameters allows the solution to be interpreted as barotropic matter stars or dark energy stars. The model is physically reasonable and satisfies the energy conditions.
Article
Astronomy & Astrophysics
Byron P. Brassel, Sunil D. Maharaj, Rituparno Goswami
Summary: The junction conditions for a higher dimensional spherically symmetric charged and anisotropic static star in Einstein-Gauss-Bonnet (EGB) gravity with nonvanishing cosmological constant are derived. It is shown that the generalised matching conditions are satisfied across the timelike boundary hypersurface of zero thickness in EGB gravity. The validity of Israel-Darmois conditions is a sufficient condition for the matching. Therefore, a complete stellar model can be generated in EGB gravity. The interior matches to the exterior higher dimensional charged Boulware-Deser spacetime with cosmological constant. The vanishing of barotropic radial pressure at the boundary of the star is also consistent with general relativity.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Shavani Naicker, Sunil D. Maharaj, Byron P. Brassel
Summary: In this study, we investigated the influence of higher order curvature terms on the static configuration of a charged dust distribution in EGB gravity. We found exact solutions to the governing equations using special functions, series, and polynomials. The results show that the charged dust model behaves well in the center region and can generate dust spheres. The higher order curvature terms have a distinct influence on the dynamics of charged dust and gravitational behavior compared to general relativity.
GENERAL RELATIVITY AND GRAVITATION
(2023)
Article
Physics, Particles & Fields
Shavani Naicker, Sunil D. Maharaj, Byron P. Brassel
Summary: In this paper, the field equations for a charged gravitating perfect fluid in Einstein-Gauss-Bonnet gravity are derived in all spacetime dimensions. The static and spherically symmetric spacetime leads to a charged condition of pressure isotropy, which is a second-order Abel differential equation. It is shown that this equation can be simplified to a first-order, nonlinear canonical differential equation in higher dimensions. The canonical form allows for an exact solution generating algorithm, resulting in implicit solutions by choosing potentials and the electromagnetic field. An exact solution to the canonical equation is found, which corresponds to the neutral model previously discovered. Additionally, three new classes of solutions are obtained by placing constraints on the canonical differential equation, without specifying gravitational potentials and electromagnetic field. When the canonical form is not applicable, other classes of exact solutions are presented using elementary and special functions (the Heun confluent functions).
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
C. Hansraj, R. Goswami, S. D. Maharaj
Summary: In this paper, the Kerr spacetime is analyzed using a semi-tetrad decomposition. The 1+1+2 covariant method is applied to describe the geometry of the Kerr spacetime outside the horizon. A comparison is made between observers in the Killing frame and the ZAMO frame, resulting in different geometrical quantities and equations. This novel approach provides new insights into the Kerr spacetime geometry in a transparent manner.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Sunil D. Maharaj, Noeleen Naidoo, Gareth Amery, Keshlan S. Govinder
Summary: The Karmarkar embedding condition in different spherically symmetrical metrics is studied using Lie symmetries. The study extends recent results by investigating the Lie symmetries for conformally flat and shear-free metrics. Additionally, the Lie symmetries for geodesic metrics and general spherical spacetimes are obtained for the first time. The study also demonstrates that the Karmarkar condition can be used to produce an embeddable relativistic radiating star with a barotropic equation of state via Lie symmetries.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Noeleen Naidoo, Sunil D. Maharaj, Keshlan S. Govinder
Summary: The objective of this study is to investigate spherically symmetric radiating stars undergoing gravitational collapse, in higher dimensional general relativity, inclusive of acceleration, expansion, shear, an electromagnetic field and a cosmological constant. Two approaches are studied to obtain exact solutions to the boundary condition with/without a linear equation state. Transformations that map the boundary condition into a new Riccati equation are investigated to obtain new exact models. The importance of these transformations in reducing the order of the boundary condition and obtaining new solutions is shown.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Multidisciplinary
Alberto K. Mathias, Jefta M. Sunzu, Sunil D. Maharaj, Jason M. Mkenyeleye
Summary: Exact solutions for charged relativistic anisotropic stars are generated using the Karmarkar condition with Einstein-Maxwell field equations and a linear equation of state. The Bannerji and Durgapal transformation is employed to transform the nonlinear differential equations and field equations. The embedding approach provides a relationship between gravitational potentials, helping to solve and integrate the field equations. The detailed physical analysis shows that the model satisfies necessary conditions such as stability, equilibrium, energy conditions, and the mass-radius relationship.
PRAMANA-JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
J. W. Jape, S. D. Maharaj, J. M. Sunzu, J. M. Mkenyeleye
Summary: We generate charged anisotropic exact models with a conformal Killing vector for static spacetime, which satisfies various physical requirements and regains some known solutions.
INDIAN JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
J. W. Jape, J. M. Sunzu, S. D. Maharaj, J. M. Mkenyeleye
Summary: Exact solutions of charged anisotropic fluid spheres with a linear equation of state are generated by incorporating conformal symmetry and an equation of state. These solutions satisfy several important physical conditions, including smooth matching, compatibility with observations, and stability requirement.
INDIAN JOURNAL OF PHYSICS
(2023)
