Puerarin partly counteracts the inflammatory response after cerebral ischemia/reperfusion via activating the cholinergic anti-inflammatory pathway

Puerarin, a major isoflavonoid derived from the Chinese medical herb radix puerariae （Gegen）, has been reported to inhibit neuronal apoptosis and play an anti-inflammatory role in focal cerebral ischemia model rats. Recent findings regarding stroke pathophysiology have recognized that anti-inflammation is an important target for the treatment of ischemic stroke. The cholinergic anti-inflammatory pathway is a highly robust neural-immune mechanism for inflammation control. This study was to investigate whether activating the cholinergic anti-inflammatory pathway can be involved in the mechanism of inhibiting the inflammatory response during puerarin-induced cerebral ischemia/reperfusion in rats. Results showed that puerarin pretreatment （intravenous injection） re- duced the ischemic infarct volume, improved neurological deficit after cerebral ischemia/reperfusion and decreased the levels of interleukin-1β, interleukin-6 and tumor necrosis factor-a in brain tissue. Pretreatment with puerarin （intravenous injection） attenuated the inflammatory response in rats, which was accompanied by janus-activated kinase 2 （JAK2） and signal transducers and activators of transcription 3 （STAT3） activation and nuclear factor kappa B （NF-KB） inhibition. These observa- tions were inhibited by the alpha7 nicotinic acetylcholine receptor （a7nAchR） antagonist a-bungarotoxin （a-BGT）. In addition, puerarin pretreatment increased the expression of a7nAchR mRNA in ischemic cerebral tissue. These data demonstrate that puerarin pretreatment strongly protects the brain against cerebral ischemia/reperfusion injury and inhibits the inflammatory re- sponse. Our results also indicated that the anti-inflammatory effect of puerarin may partly be medi- ated through the activation of the cholinergic anti-inflammatory pathway.

Users'experience matter:Delay sensitivity-aware computation offloading in mobile edge computing

As a promising computing paradigm,Mobile Edge Computing(MEC)provides communication and computing capability at the edge of the network to address the concerns of massive computation requirements,constrained battery capacity and limited bandwidth of the Internet of Things(IoT)systems.Most existing works on mobile edge task ignores the delay sensitivities,which may lead to the degraded utility of computation offloading and dissatisfied users.In this paper,we study the delay sensitivity-aware computation offloading by jointly considering both user's tolerance towards delay of task execution and the network status under computation and communication constraints.Specifically,we use a specific multi-user and multi-server MEC system to define the latency sensitivity of task offloading based on the analysis of delay distribution of task categories.Then,we propose a scoring mechanism to evaluate the sensitivity-dependent utility of task execution and devise a Centralized Iterative Redirection Offloading(CIRO)algorithm to collect all information in the MEC system.By starting with an initial offloading strategy,the CIRO algorithm enables IoT devices to cooperate and iteratively redirect task offloading decisions to optimize the offloading strategy until it converges.Extensive simulation results show that our method can significantly improve the utility of computation offloading in MEC systems and has lower time complexity than existing algorithms.

Determination of the spin parameter and the inclination angle from the primary and secondary images caused by gravitational lensing

We study the primary images(PIs)and secondary images(SIs)caused by strong gravitational lensing around a Kerr black hole shadow,which carry some essential signatures related to the black hole space-time.We define a new celestial coordinate,whose origin is the center of the black hole shadow,to locate the PIs and SIs of luminous celestial objects.Based on the dragging effect caused by the rotating black hole and the inclination angle of the observer,the relative positions between the PIs and SIs are different for different values of the Kerr spin parameter a and the observer's inclination angle i;hence,it can be used to determine the values of a and i.We propose a specific approach to measure a and i using the PIs and SIs.The time delays between the PIs and SIs are different for different values of a and i.The time delays,in conjunction with the relative positions between the PIs and SIs,can enable us to measure a and i more precisely.These PIs and SIs around the black hole shadow act as unique fingerprints for the black hole space-time,using which we can further determine other parameters of different types of compact objects and verify various theories of gravity.Our results provide a new method to implement parameter estimation in the study of black hole physics and astrophysics.

Surface geometry and shadow of a Schwarzschild black hole with a halo

We studied the surface geometry and shadows of a Schwarzschild black hole with a halo containing quadrupolar and octopolar terms.It was found that the quadrupole term causes a Schwarzschild black hole to be prolate at the quadrupole strength Q<0 and oblate at Q>0,and the octopole term causes to the shadow stretch upward at the octopolar strength ngth O<0 and downward at O>0.The shadow of a Schwarzschild black hole with a halo stretches and squeezes along the horizontal direction at Q<0 and Q>0,respectively.Meanwhile,the black hole shadow shifts upward at O<0 and downward at O>0.We present the light rays that form the shadow boundary to explain the emergence of the extraordinary patterns of the black hole shadow with quadrupole and octopole terms.From the observable width W,height H,oblateness K,and distortion parameterδcof the black hole shadow,we can determine the quadrupole and octopolar strengths of a Schwarzschild black hole with a halo.Our results show that the quadrupolar and octopolar terms yield a series of interesting patterns for the shadow of a Schwarzschild black hole with a halo.

基于磁诱导微柱阵列可无线充电的超灵敏柔性传感器

为实现在宽感知范围内对微小压力变化的精确测量,提高柔性压力传感器的灵敏度和工作范围显得尤为迫切.然而,由于柔性传感器所使用的软基质材料的固有局限,实现超过100 kPa工作范围同时维持1000 kPa^(-1)以上的灵敏度仍然是一项挑战.本文报道了一种磁诱导的多孔弹性体(PDMS),分别以微柱阵列(MPA)作为传感材料和具有编织结构的导电镍作为电极.由于MPA的独特结构和电极的织构形态,所开发的传感器具有10,268 kPa^(-1)(0.6–170 kPa范围内)的超高灵敏度,高达500 kPa的工作范围,并具有长期耐用性.并实现了最小0.25 Pa的检测压力和3 ms的响应时间.此外,将柔性传感器、柔性超级电容器和感应线圈进行一体化集成,实现了对传感器的无线能量传输,并在低压至高压范围内对传感实际应用能力进行了测试.本项研究工作将具有微结构的高性能传感器与无线充电系统结合在一起,为开发下一代柔性电子产品提供了一种新颖的方法.

A novel non-stoichiometric medium-entropy carbide stabilized by anion vacancies

Recently,high-entropy ceramics have attracted considerable attentions because of comprehensive physical and chemical properties of high hardness,fracture toughness,and conductivity.However,as a newly emerging class of materials,the synthesis,performance and applications of high-entropy ceramics are subject to further development.Here,we reported a new non-stoichiometric TiC0.4/WC/0.5Mo2C medium-entropy carbide(MEC)with a rock-salt structure.Attributed to the solid solution strengthening and twinning strengthening,the TiCO0.4/WC/0.5Mo2C sintered at 1900℃by spark plasma sintering(SPS)shows superior mechanical behaviors of microhardness(21.7 GPa),which exceeds that expected from the rule of mixture(ROM)of three individual metal carbides(19.1 GPa)and good fracture toughness(5.3 MPa m1/2).Significantly,the bulk synthesized via high-pressure and high-temperature(HPHT)sintering possesses smaller grain size and shows better comprehensive mechanical properties of microhardness(23.7 GPa)and fracture toughness(6.2 MPa m1/2).In addition,the effect of anion vacancies on the thermodynamic stability and synthesizability of TiC0.4/WC/0.5Mo2C was analyzed via quantitatively calculated entropy.Vacancies could significantly enhance the configuratio nal entropy of mixing of the solid phase.The introduction of vacancy defects may expand synthetic path for entropy-stabilized ceramics,especially for multi-component high tempe rature refractory ceramics.

Chaotic shadows of black holes:a short review

We give a brief review on the formation and the calculation of black hole shadows.Firstly,we introduce the concept of a black hole shadow and the current works on a variety of black hole shadows.Secondly,we present the main methods of calculating photon sphere radius and shadow radius,and then explain how the photon sphere affects the boundary of black hole shadows.We review the analytical calculation for black hole shadows which have analytic expressions for shadow boundary due to the integrable photon motion system.And we introduce the fundamental photon orbits which can explain the patterns of black hole shadow shape.Finally,we review the numerical calculation of black hole shadows with the backward ray-tracing method and introduce some chaotic black hole shadows with self-similar fractal structures.Since the gravitational waves from the merger of binary black holes have been detected,we introduce a couple of shadows of binary black holes,which all have eyebrowlike shadows around the main shadows with the fractal structures.We discuss the invariant phase space structures of the photon motion system in black hole space-time,and explain the formation of black hole shadow is dominated by the invariant manifolds of certain Lyapunov orbits near the fixed points.

Extraordinary toughening enhancement in nonstoichiometric vanadium carbide

1.Introduction Fracture toughness is the ability of materials against both the initiation and propagation of cracks[1],which is a crucial mechanical property for safety-critical applications of structural materials.Although the yield strength of ceramics is significantly higher than that of metallic materials,the fracture toughness is severely lower than that of metallic materials due to the strongly directional covalent bonding[1-3].For a long time,how to improve the fracture toughness of ceramics without the deterioration of strength(or hardness)has been one of the most challenging problems in materials science.