Results 121 to 130 of about 707,832 (374)

Gravitational lensing by transparent Janis–Newman–Winicour naked singularities

European Physical Journal C: Particles and Fields
The Janis–Newman–Winicour (JNW) spacetime can describe a naked singularity with a photon sphere that smoothly transforms into a Schwarzschild black hole. Our analysis reveals that photons, upon entering the photon sphere, converge to the singularity in a
Deyou Chen, Yiqian Chen, Peng Wang, Tianshu Wu, Houwen Wu   +4 more
doaj   +1 more source

Progressive Insights into 3D Bioprinting for Corneal Tissue Restoration

Advanced Healthcare Materials, EarlyView.
This review explores the potential of 3D bioprinting to replicate the complex structure and function of the human cornea. It highlights key advances in bioink development, printing modalities, and in vivo performance, while addressing current challenges and emerging strategies. The review emphasizes bioprinting's promise to overcome donor shortages and
Ilayda Namli, Deepak Gupta, Yogendra Pratap Singh, Pallab Datta, Muhammad Rizwan, Mehmet Baykara, Ibrahim T. Ozbolat   +6 more
wiley   +1 more source

Gravitational collapse in Rastall gravity

Physics Letters B, 2019
We study spherically symmetric gravitational collapse of a homogeneous perfect fluid in Rastall gravity. Considering a linear equation of state (EoS) for the fluid profiles, we examine the conditions under which the collapse scenario could end in a ...
A. H. Ziaie, H. Moradpour, S. Ghaffari
doaj   +1 more source

Resolving Gravitational Singularities

, 2008
We review recent progress on the resolution of gravitational singularities in string theory. The main example is the fundamental string in five dimensions which is singular in the standard supergravity description but regular after taking into account higher derivative corrections determined by anomalies and supersymmetry.
openaire   +2 more sources

Adsorption and Separation by Flexible MOFs

Advanced Materials, EarlyView.
Flexible metal–organic frameworks (MOFs) present significant potential for gas storage and separation due to their structural dynamic. This review explores the rationale behind the flexible MOFs' enhanced working capacity and separation factors. It also addresses key challenges, including phase transition kinetics, crystal robustness, cycling, shaping,
Irena Senkovska, Volodymyr Bon, Antonia Mosberger, Yutong Wang, Stefan Kaskel   +4 more
wiley   +1 more source

Physical nature of the central singularity in spherical collapse

, 2001
We examine here the nature of the central singularity forming in the spherically symmetric collapse of a dust cloud and it is shown that this is always a strong curvature singularity where gravitational tidal forces diverge powerfully.
B. Waugh, C. J. S. Clarke, C. J. S. Clarke, D. Christodoulou, F. J. Tipler, G. Lemaître, H. Bondi, I. H. Dwivedi, I. H. Dwivedi, I. H. Dwivedi, J. Oppenheimer, P. S. Joshi, P. S. Joshi, P. Yodzis, P. Yodzis, R. C. Tolman, R. Geroch, R. Hagedorn, R. P. A. C. Newman, R. Penrose, S. Jhingan, S. S. Deshingkar, S. W. Hawking, T. Harada   +23 more
core   +2 more sources

Recent Advances in Wide‐Bandgap Perovskite Solar Cells

Advanced Materials, EarlyView.
Ubiquitous defects predominately account for photo‐instability and open‐circuit voltage losses in wide‐bandgap perovskite solar cells (WBG PSCs). This review comprehensively presents the underlying impact mechanisms, summarizes the advanced optimization strategies across various functional layers and their interfaces to develop efficient and stable WBG
Jianjun Mei, Feng Yan
wiley   +1 more source

On the Role of Initial Data in the Gravitational Collapse of Inhomogeneous Dust

, 1995
We consider here the gravitational collapse of a spherically symmetric inhomogeneous dust cloud described by the Tolman-Bondi models. By studying a general class of these models, we find that the end state of the collapse is either a black hole or a ...
A. C. Newman, D. Christodoulou, D. M. Eardley, H. Bondi, I. H. Dwivedi, J. R. Oppenheimer, P. S. Joshi, P. S. Joshi, P. S. Joshi, R. C. Tolman, R. Penrose, T. P. Singh   +11 more
core   +1 more source

Wireless Acousto‐Piezoelectric Conduit with Aligned Nanofibers for Neural Regeneration

Advanced Materials, EarlyView.
An ultrasound‐driven, highly aligned piezoelectric nanofiber‐based nerve guidance conduit (APNF‐NGC) designed for effective peripheral nerve repair has been demonstrated in this study. Featuring aligned topology, cell‐adhesive surfaces, and an axial electric field, the APNF‐NGC collectively promotes significant nerve regeneration.
Sera Jeon, Dabin Kim, Min‐Young Jo, Chae‐Min Ryu, Daniel Sanghyun Cho, Byung‐Ok Choi, Jae Kwang Kim, Miso Kim, Sang‐Woo Kim   +8 more
wiley   +1 more source

The Mathematical Origin of Gravitational Singularities

Journal of Modern Physics, 2020
In this note we give a geometrical presentation to the 4D Riemannian curvature as it relates to the Newtonian gravity in the 4D Lorentz manifold. The compacting of the proper time as is necessary for the unification with the Maxwell electrodynamics, as given by Einstein and Kaluza-Klein, should the universe be only of 4D space-time, led to the concept ...
Wan Ki Chow, Kai Wai Wong
openaire   +3 more sources