We investigate the shadows and photon spheres of the four-dimensional Gauss–Bonnet black hole with the static and infalling spherical accretions. We show that, for both cases, there always exist ...shadows and photon spheres. The radii of the shadows and photon spheres are independent of the profiles of accretion for a fixed Gauss–Bonnet constant, implying that the shadow is a signature of the spacetime geometry and it is hardly influenced by accretion. Because of the Doppler effect, the shadows of the infalling accretion are found to be darker than in the static case. We also investigate the effect of the Gauss–Bonnet constant on the shadow and photon spheres, and we find that the larger the Gauss–Bonnet constant is, the smaller the radii of the shadow and photon spheres will be. In particular, the observed specific intensity increases as the Gauss–Bonnet constant grows.
We investigate the effects of quintessence dark energy on the shadows of black hole, surrounded by various profiles of accretions. For the thin-disk accretion, the images of the black hole comprises ...the dark region and bright region, including direct emission, lensing rings and photon rings. Although their details depend on the form of the emission, generically, direct emission plays a major role for the observed brightness of the black hole, while the lensing ring makes a small contribution and the photon ring makes a negligible contribution. The existence of a cosmological horizon also plays an important role in the shadows, since the observer in the domain of outer communications is near the cosmological horizon. For spherically symmetric accretion, static and infalling matters are considered. We find that the positions of photon spheres are the same for both static and infalling accretions. However, the observed specific intensity of the image for infalling accretion is darker than for static accretion, due to the Doppler effect of the infalling motion.
Conductive polymers (CPs) are promising organic semiconductors for many essential applications because of their tunable physical/chemical properties, mechanical flexibility, low weight, reversible ...doping, good biocompatibility, and scalable production. However, CPs have not achieved their expected application potential in conventional processing methods. Electrospinning is a simple and highly versatile technique that can be used for mass fabrication of continuous ultrafine fibers from various polymers and composites. Electrospun fibers have many advantages, including uniformity, porosity, large surface areas, and mechanical strength, which present new application areas of CPs, and solve a number of problems related to the applicability of the polymers. However, as CPs are soluble and brittle, electrospinning requires a specific strategy. Different approaches, including direct electrospinning of CPs into fibers, co-electrospinning of blends of CPs and other spinnable carrier polymers, and synthesizing of electrospun fiber-template, have been developed to solve this problem. In this review, the recent achievements of fabricating CP-based ultrafine fibers using an electrospinning process are summarized, along with the characterization of their physical–chemical properties, such as electrical conductivity, wettability, and mechanical and thermal properties, which are further improved by modification. More emphasis is placed on the potential applications of electrospun CP ultrafine fibers in bio-/chemical sensors, artificial muscles, neural electrodes/interfaces, tissue regeneration, controlled drug release, flexible/stretchable electronic devices, energy storage, and electromagnetic interference shielding materials. Furthermore, the current challenges and future opportunities are also addressed.
N6-methyladenosine (m6A) modification is the most pervasive modification in mRNA, and has been considered as a new layer of epigenetic regulation on mRNA processing, stability and translation. ...Despite its functional significance in various physiological processes, the role of the m6A modification involved in breast cancer is yet fully understood.
We used the m6A-RNA immunoprecipitation sequencing to identify the potential targets in breast cancer. To determine the underlying mechanism for the axis of FTO-BNIP3, we performed a series of in vitro and in vivo assays in 3 breast cancer cell lines and 36 primary breast tumor tissues and 12 adjunct tissues.
We showed that FTO, a key m6A demethylase, was up-regulated in human breast cancer. High level of FTO was significantly associated with lower survival rates in patients with breast cancer. FTO promoted breast cancer cell proliferation, colony formation and metastasis in vitro and in vivo. We identified BNIP3, a pro-apoptosis gene, as a downstream target of FTO-mediated m6A modification. Epigenetically, FTO mediated m6A demethylation in the 3'UTR of BNIP3 mRNA and induced its degradation via an YTHDF2 independent mechanism. BNIP3 acts as a tumor suppressor and is negatively correlated with FTO expression in clinical breast cancer patients. BNIP3 dramatically alleviated FTO-dependent tumor growth retardation and metastasis.
Our findings demonstrate the functional significance of the m6A modification in breast cancer, and suggest that FTO may serve as a novel potential therapeutic target for breast cancer.
Microglia/macrophages are the major immune cells involved in the defence against brain damage. Their morphology and functional changes are correlated with the release of danger signals induced by ...stroke. These cells are normally responsible for clearing away dead neural cells and restoring neuronal functions. However, when excessively activated by the damage-associated molecular patterns following stroke, they can produce a large number of proinflammatory cytokines that can disrupt neural cells and the blood-brain barrier and influence neurogenesis. These effects indicate the important roles of microglia/macrophages in the pathophysiological processes of stroke. However, the modifiable and adaptable nature of microglia/macrophages may also be beneficial for brain repair and not just result in damage. These distinct roles may be attributed to the different microglia/macrophage phenotypes because the M1 population is mainly destructive, while the M2 population is neuroprotective. Additionally, different gene expression signature changes in microglia/macrophages have been found in diverse inflammatory milieus. These biofunctional features enable dual roles for microglia/macrophages in brain damage and repair. Currently, it is thought that the proper inflammatory milieu may provide a suitable microenvironment for neurogenesis; however, detailed mechanisms underlying the inflammatory responses that initiate or inhibit neurogenesis remain unknown. This review summarizes recent progress concerning the mechanisms involved in brain damage, repair and regeneration related to microglia/macrophage activation and phenotype transition after stroke. We also argue that future translational studies should be targeting multiple key regulating molecules to improve brain repair, which should be accompanied by the concept of a "therapeutic time window" for sequential therapies.
After studying the energy–momentum relation of charged particles’ Hamilton–Jacobi equations, we discuss the laws of thermodynamics and the weak cosmic censorship conjecture in torus-like black holes. ...We find that both the first law of thermodynamic as well as the weak cosmic censorship conjecture are valid in both the normal phase space and extended phase space. However, the second law of thermodynamics is only valid in the normal phase space. Our results show that the first law and weak cosmic censorship conjecture do not depend on the phase spaces while the second law depends. What’s more, we find that the shift of the metric function that determines the event horizon take the same form in different phase spaces, indicating that the weak cosmic censorship conjecture is independent of the phase space.
Phase structure of the quintessence Reissner–Nordström–AdS black hole is probed by the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result ...shows that, as the case of the thermal entropy, both the observables exhibit the Van der Waals-like phase transition. To reinforce this conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.
In this article we report on the development of polymeric micelles that can integrate multiple functions in one system, including the capability to accommodate a combination of therapeutic entities ...with different physicochemical properties (i.e., siRNA and doxorubicin; DOX), passive and active cancer targeting, cell membrane translocation, and pH-triggered drug release. A micellar system was constructed from degradable poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) block copolymers with functional groups on both blocks. The functional group on the PCL block was used to incorporate short polyamines for complexation with siRNA or to chemically conjugate DOX via a pH-sensitive hydrazone linkage. A virus mimetic shell was conferred by attaching two ligands, i.e., the integrin αvβ3-specific ligand (RGD4C) for active cancer targeting and the cell-penetrating peptide TAT for membrane activity. This system was used to improve the efficacy of DOX in multidrug-resistant MDA-MB-435 human tumor models that overexpress P-glycoprotein (P-gp), by simultaneous intracellular delivery of DOX and siRNA against P-gp expression. The carrier was tagged with near-infrared fluorescent imaging probes to provide a means to follow the fate of the system in vivo upon intravenous administration. Dy677-labeled siRNA was also used to assess the in vivo stability of the siRNA carrier. This multifunctional polymeric micellar system was shown to be capable of DOX and siRNA delivery to their intracellular targets, leading to the inhibition of P-gp-mediated DOX resistance in vitro and targeting of αvβ3-positive tumors in vivo.
The indoor air quality is of prime importance for human daily life and health, for which the adsorbents like zeolites and silica‐gels are widely used for air dehumidification and harmful gases ...capture. Herein, we develop a pore‐nanospace post‐engineering strategy to optimize the hydrophilicity, water‐uptake capacity and air‐purifying ability of metal‐organic frameworks (MOFs) with long‐term stability, offering an ideal candidate with autonomous multi‐functionality of moisture control and pollutants sequestration. Through variant tuning of organic‐linkers carrying hydrophobic and hydrophilic groups in the pore‐nanospaces of prototypical UiO‐67, a moderately hydrophilic MOF (UiO‐67‐4Me‐NH2‐38 %) with high thermal, hydrolytic and acid‐base stability is screened out, featuring S‐shaped water sorption isotherms exactly located in the recommended comfortable and healthy ranges of relative humidity for indoor ventilation (45 %–65 % RH) and adverse health effects minimization (40–60 % RH). Its exceptional attributes of water‐uptake working capacity/efficiency, contaminants removal, recyclability and regeneration promise a great potential in confined indoor environment application.
A moderately hydrophilic MOF of UiO‐67‐4Me‐NH2‐38 % with high thermal, hydrolytic and acid‐base stability has been obtained by a pore‐nanospace post‐engineering strategy, which shows ideal S‐shaped water‐sorption isotherm, high water‐uptake working capacity and efficiency in the ASHRAE recommended humidity range, and prior capture ability of harmful organic and inorganic vapors, providing a promising candidate for autonomous indoor humidity control and air purification.
Oxysulfide semiconductors have narrow bandgaps suitable for water splitting under visible-light irradiation, because the electronegative sulfide ions negatively shift the valence band edges of the ...corresponding oxides
. However, the instability of sulfide ions during the water oxidation is a critical obstacle to simultaneous evolution of hydrogen and oxygen
. Here, we demonstrate the activation and stabilization of Y
Ti
O
S
, with a bandgap of 1.9 eV, as a photocatalyst for overall water splitting. On loading of IrO
and Rh/Cr
O
as oxygen and hydrogen evolution co-catalysts, respectively, and fine-tuning of the reaction conditions, simultaneous production of stoichiometric amounts of hydrogen and oxygen was achieved on Y
Ti
O
S
during a 20 h reaction. The discovery of the overall water splitting capabilities of Y
Ti
O
S
extends the range of promising materials for solar hydrogen production.
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