1,230 research outputs found
Unconventional superfluidity of superconductivity on Penrose lattice
We theoretically investigate the gap function, superfluid density and the
transition temperature of the superconductivity (SC) on semi-periodic Penrose
lattice, where an attractive Hubbard model is adopted as an example. Firstly,
we clarify that the gap function, density of states and superfluid density are
all positively correlate to the extended degree of single particle states
around the Fermi energy. Secondly, we identify that the paramagnetic component
of the superfluid density does not decay to zero in the thermodynamic limit,
which is completely different from the periodic system. The difference between
the diamagnetic and paramagnetic currents keeps stable with whatever scaling,
which is consistent with recent experimental results that although the
superfluid density is lower than that of the periodic system, the system has
bulk SC. Thirdly, we find that both the superfluid density and SC transition
temperature can be boosted with the increase of disorder strength, which should
be general to quasicrystal but unusual to periodic systems, reflecting the
interplay between the underlying geometry and disorder.Comment: 7 pages, 4 figures. version accepted by Sci. China-Phys. Mech. &
Astro
Functional maturation of immature β cells: A roadblock for stem cell therapy for type 1 diabetes
Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease caused by the specific destruction of pancreatic islet β cells and is characterized as the absolute insufficiency of insulin secretion. Current insulin replacement therapy supplies insulin in a non-physiological way and is associated with devastating complications. Experimental islet transplantation therapy has been proven to restore glucose homeostasis in people with severe T1DM. However, it is restricted by many factors such as severe shortage of donor sources, progressive loss of donor cells, high cost, etc. As pluripotent stem cells have the potential to give rise to all cells including islet β cells in the body, stem cell therapy for diabetes has attracted great attention in the academic community and the general public. Transplantation of islet β-like cells differentiated from human pluripotent stem cells (hPSCs) has the potential to be an excellent alternative to islet transplantation. In stem cell therapy, obtaining β cells with complete insulin secretion in vitro is crucial. However, after much research, it has been found that the β-like cells obtained by in vitro differentiation still have many defects, including lack of adult-type glucose stimulated insulin secretion, and multi-hormonal secretion, suggesting that in vitro culture does not allows for obtaining fully mature β-like cells for transplantation. A large number of studies have found that many transcription factors play important roles in the process of transforming immature to mature human islet β cells. Furthermore, PDX1, NKX6.1, SOX9, NGN3, PAX4, etc., are important in inducing hPSC differentiation in vitro. The absent or deficient expression of any of these key factors may lead to the islet development defect in vivo and the failure of stem cells to differentiate into genuine functional β-like cells in vitro. This article reviews β cell maturation in vivo and in vitro and the vital roles of key molecules in this process, in order to explore the current problems in stem cell therapy for diabetes
Clinical Application of DDM/rhBMP-2 in Implant Dentistry
Recombinant human bone morphogenetic protein-2 (rhBMP-2) is well-known osteoinductive growth factors that can be used along with various carriers. Demineralized dentin matrix (DDM) that has osteoinductive and osteoconductive capacities was developed as potential candidate for rhBMP-2 carrier that has its endogenous growth factors and fulfils the requirements such as controlled release kinetics, biocompatibility, biodegradabilities and bone forming capacity. DDM loaded with rhBMP-2 (DDM/rhBMP-2) have been subjected to in vitro, in vivo studies for the purpose of proving the clinical safety and efficacy. Recently the clinical trials and outcomes of DDM/rhBMP-2 have also proved this composite to be safe and efficient in terms of enhanced bone formation, remodeling capacity and reduced concentration of rhBMP-2 in implant dentistry in Korea. This chapter will introduce the clinical application of DDM/rhBMP-2 in implant dentistry based on the related experimental and clinical researches
General bubble expansion at strong coupling
The strongly-coupled system like the quark-hadron transition (if it is of
first order) is becoming an active play-yard for the physics of cosmological
first-order phase transitions. However, the traditional field theoretic
approach to strongly-coupled first-order phase transitions is of great
challenge, driving recent efforts from holographic dual theories with explicit
numerical simulations. These holographic numerical simulations have revealed an
intriguing linear correlation between the phase pressure difference (pressure
difference away from the wall) to the non-relativistic terminal velocity of an
expanding planar wall, which has been reproduced analytically alongside both
cylindrical and spherical walls from perfect-fluid hydrodynamics in our
previous study but only for a bag equation of state. We have also found in our
previous study a universal quadratic correlation between the wall pressure
difference (pressure difference near the bubble wall) to the non-relativistic
terminal wall velocity regardless of wall geometries. In this paper, we will
generalize these analytic relations between the phase/wall pressure difference
and terminal wall velocity into a more realistic equation of state beyond the
simple bag model, providing the most general predictions so far for future
tests from holographic numerical simulations of strongly-coupled first-order
phase transitionsComment: 22 pages, 10 figure
Preparation and characterization of realgar nanoparticles and their inhibitory effect on rat glioma cells
Extended dissipaton equation of motion for electronic open quantum systems: Application to the Kondo impurity model
In this paper, we present an extended dissipaton equation of motion for
studying the dynamics of electronic impurity systems. Compared with the
original theoretical formalism, the quadratic couplings are introduced into the
Hamiltonian accounting for the interaction between the impurity and its
surrounding environment. By exploiting the quadratic dissipaton algebra, the
proposed extended dissipaton equation of motion offers a powerful tool for
studying the dynamical behaviors of electronic impurity systems, particularly
in situations where nonequilibrium and strongly correlated effects play
significant roles. Numerical demonstrations are carried out to investigate the
temperature dependence of the Kondo resonance in the Kondo impurity model.Comment: 6 pages, 1 figur
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