Quintessence anisotropic stellar models in quadratic and Born-Infeld modified teleparallel Rastall gravity

This study aims to discuss anisotropic solutions that are spherically symmetric in the quintessence field,which describe compact stellar objects in the modified Rastall teleparallel theory of gravity.To achieve this goal,the Krori and Barua arrangement for spherically symmetric components of the line element is incorporated.We explore the field equations by selecting appropriate off-diagonal tetrad fields.Born-Infeld function of torsion f(T)=β√λT+1-1 and power law form h(T)=δTn are used.The Born-Infeld gravity was the first modified teleparallel gravity to discuss inflation.We use the linear equation of state pr=ξρto separate the quintessence density.After obtaining the field equations,we investigate different physical parameters that demonstrate the stability and physical acceptability of the stellar models.We use observational data,such as the mass and radius of the compact star candidates PSRJ 1416-2230,Cen X-3,&4U 1820-30,to ensure the physical plausibility of our findings.

Stability of LRS Bianchi type-I cosmological models in f(R,T)-gravity

This paper examines the stability of the transition from the early decelerating stage of the Universe to the recent accelerating stage for the perfect fluid cosmological locally rotationally symmetric(LRS) Bianchi-I model in f(R, T) theory. To determine the solution of field equations, the idea of a timevarying deceleration parameter(DP) which yields a scale factor, for which the Universe attains a phase transition scenario and is consistent with recent cosmological observations, is used. The time-dependent DP yields a scale factor a=exp■, where β and k are respectively arbitrary and integration constants. By using the recent cons_traints(H_0 _= 73.8, and q_0 =-0.54) from Type Ia Supernova(SN Ia) data in combination with Baryonic Acoustic Oscillations(BAO) and Cosmic Microwave Background(CMB) observations(Giostri et al.), we obtain the values of β = 0.0062 and k = 0.000016 for which we have derived a cosmological model from the early decelerated phase to the present accelerating phase. By applying_ other r_ecent constraints(H_0 = 73.8, q_0 =-0.73) from SNe Ia Union data(Cunha), we obtain the values of β = 0.0036 and k = 0.000084 for which we have derived a cosmological model in the accelerating phase only. We have compared both models with experimental data. The stability of the background solution has been examined also for the metric perturbations alongside the properties of future singularities in a Universe ruled by dark energy with phantom type fluid. We demonstrate the presence of a stable fixed point with a condition of state ω <-1 and numerically affirm this is really a late-time attractor in the ghost overwhelmed Universe. Some physical and geometric properties of the model are found and examined.

Transient acceleration in f(T) gravity

Recently an f （T） gravity based on the modification of teleparallel gravity was proposed to ex-plain the accelerated expansion of the universe. We use observational data from type Ia supernovae, baryon acoustic oscillations, and cosmic microwave background to constrain this f（T） theory and reconstruct the effective equation of state and the deceleration parameter. We obtain the best-fit values of parameters and find an interesting result that the constrained f（T） theory allows for the accelerated Hubble expansion to be a transient effect.

Magnetic Field of a Compact Spherical Star under f(R,T) Gravity

We present the interior solutions of distributions of magnetized fluid inside a sphere in f（R, T） gravity. Tile magnetized sphere is embedded in an exterior Reissner NordstrOm metric. We assume that all physical quantities are in static equilibrium. The perfect fluid matter is studied under a particular form of the Lagrangian density f（R, T）. The magnetic field profile in modified gravity is calculated. Observational data of neutron stars are used to plot suitable models of magnetized compact objects. We reveal the effect of f（R, T） gravity on the magnetic field profile, with application to neutron stars, especially highly magnetized neutron stars found in x-ray pulsar systems. Finally, the effective potential Veff and innermost stable circular orbits, arising out of the motion of a test particle of negligible mass influenced by attraction or repulsion from the massive center, are discussed.

General Covariant Conservation Law of Energy-Momentum in f(R)Gravity

In the light of the local Lorentz transformations and the general Noether theorem, a new formulate ofthe general covariant energy-momentum conservation law in f(R) gravity is obtained, which does not depend on thecoordinative choice.

A Note on the Cosmological Constant in <i>f</i>(<i>R</i>) Gravity

The starting point in this note is f(R) modified gravity in a cosmological setting. We assume a spatially flat universe to describe late-time cosmology and the perfect-fluid equation of state to model the hypothesized dark energy. Given that on a cosmological scale, f(R) modified gravity must remain close to Einstein gravity to be consistent with observation, it was concluded that either (1) Einstein’s cosmological constant was the only acceptable model for the accelerated expansion, or that (2) the equation of state for dark energy was far more complicated than the perfect-fluid model and might even exclude a constant w.

Dynamics of Bianchi I Universe in Extended Gravity with Scale Factors

In this paper, the dynamical behavior of an anisotropic universe in an extended gravity e.g. the f (R,T ) theory of gravity is studied. We use f (R,T ) = R + 2μT , where R is the Ricci scalar, T is the trace of energy-momentum tensor and μ is a constant. Two cosmological models are constructed using the power law expansion and hybrid law cosmology in Bianchi type I universe, where the matter field is considered to be a perfect fluid. It is found that in both the cases the anisotropic behavior is in agreement with the observational results. The state finder diagnostic pair and energy conditions are also calculated and analyzed.

Modified <i>f(R)</i>Gravity and Thermodynamics of Time-Dependent Wormholes at Event Horizon

In the context of modified gravity theory, we study time-dependent wormhole spacetimes in the radiation background. In this framework, we attempt to generalize the thermodynamic properties of time-dependent wormholes in gravity. Finally, at event horizon, the rate of change of total entropy has been discussed.

Phantom and Quintessence Fields Coupled to Scalar Curvature in General <i>f(R)</i>Gravity Theory

This paper reviews the development of f(R) gravity theory and Phantom and Quintessence fields. Specifically, we present a new general action of f(R) gravity and Phantom and Quintessence fields coupled to scalar curvature. Then, we deduce Euler-Lagrange Equations of different fields, matter tensor and effective matter tensor. Additionally, this paper obtains the general pressure, density and speed sound of the new general field action, and investigates different cosmological evolutions with inflation. Further, this paper investigates a general f(R) gravity theory with a general matter action and obtains the different field equations, general matter tensor and effective matter tensor. Besides, this paper obtains the effective Strong Energy Condition (SEC) and effective Null Energy Condition (NEC). Then, we prove that when f(R) approaches to R, the effective SEC and the effective NEC approach to the usual SEC and the usual NEC, respectively. Finally, this paper presents a general action of f(R) gravity, Quintessence and Phantom fields and their applications.

Late Time Behavior of the Cosmological Model in Modified Theory of Gravity

We report a viable exponential gravity model for the accelerated expansion of the universe in Bianchi VIh space-time. By considering the estimated physical parameters, the cosmological models are constructed and analyzed in detail. We found that the state parameter in both the models increases to a higher negative range in an early epoch of the phantom domain and it goes to the positive domain at a late phase of the evolution. The effective cosmological constant remains in a positive domain for both models, which is a good sign of accelerating expansion of the universe.

Time Varying Deceleration Parameter in <i>f</i>(<i>R</i>, <i>T</i>) Gravity

In the present study, a homogeneous and anisotropic LRS Bianchi type I universe model is considered in f(R, T) theory of gravity. In order to find an exact solution of the field equations of the model, the model presented is based on a unique condition of periodically time varying deceleration parameter. The physical and geometrical characteristics of the universe model have been studied. It has been shown that the model has point-type singularity and all the cosmological parameters possess periodic time behavior. The model has a cyclic expansion history, for example, the model starts with the decelerating expansion, and later it transits to an accelerating phase of expansion and then goes to super-exponential phase of expansion in a period.

Granofin~ Easy F-90与TANFOR^(TM) T-A结合鞣制研究

采用Granofin~Easy F-90(F-90)对绵羊软化裸皮进行预鞣,并对预鞣的坯革进行无盐浸酸使浴液p H值降至2.5~3.0,然后加入TANFORTMT-A(T-A)鞣剂进行鞣制。试验结果发现:当F-90用量≥4%时,预鞣的坯革不发生膨胀;在F-90用量为4%时,预鞣坯革的收缩温度稳定在70~72℃,结合鞣制的白湿革收缩温度随着T-A用量的增加逐步提高,当T-A用量超过4%时,收缩温度升高不明显,并趋于平衡达到82.3℃;结合鞣制与F-90和T-A单独鞣制相比,鞣制的白湿革耐湿热稳定性提高,耐介质能力增强,纤维分散程度增大。这种基于F-90预鞣的T-A无盐浸酸结合鞣制技术思路是一种清洁化的白湿革生产方法,不仅实现了无盐浸酸鞣制,而且可以获得综合性能良好的白湿革,该工艺方法具有良好的应用前景。

线性相连的(r,s,t)/(l,m,n):F格点系统的可靠性

线性相连的(r,s,t)/(l,m,n):F格点系统是由l×m×n个部件依次排列成一个长方体形状,系统失效当且仅当至少有一个由r×s×t相邻的部件排列成的一个子长方体中所有部件都失效,三维线性连续失效系统(k3/n3;F)是其特殊情形。本文给出了线性相连的(r,s,t)/(l,m,n):F格点系统的上、下界.

基于STR7IX+MF RC500架构的射频识别系统设计

本设计采用STR710FZ2T6作为微处理器,充分利用RFID的非接触身份认证特性,将设备信息储存在标签(Tag)中,并通过RS232在PC机上显示出来。整个系统由STR710FZ2T6微处理器、MF RC500射频芯片、主机管理系统等部分构成。该系统实现了智能化的产品监控和管理,提高了设备管理的效率及其准确可靠性。

Non-static plane symmetric perfect fluid solutions and Killing symmetries in f(R,T)gravity

In this paper,the non-static solutions for perfect fluid distribution with plane symmetry in f(R,T)gravitational theory are obtained.Firstly,using the Lie symmetries,symmetry reductions are performed for considered vector fields to reduce the number of independent variables.Then,corresponding to each reduction,exact solutions are obtained.Killing vectors lead to different conserved quantities.Therefore,we figure out the Killing vector fields corresponding to all derived solutions.The derived solutions are further studied and it is observed that all of the obtained spacetimes,at least admit to the minimal symmetry group which consists of δ_(y),δ_(z) and -zδ_(y)+yδ_(z).The obtained metrics,admit to 3,4,6,and 10,Killing vector fields.Conservation of linear momentum in the direction of y and z,and angular momentum along the x axis is provided by all derived solutions.

On the existence and stability of traversable wormhole solutions with novel shapefunctions in the framework of F(R,L_(m))gravity

In this work,we have explored wormhole(WH)solutions in F(R,L_(m))gravity by assuming the Morris-Thorne WH metric and F(R,Lm)=R/2+(1+γR)L_(m),whereγis the free model parameter.We determined the WH solutions by utilizing two newly developed shape functions(SF)that satisfy all basic conditions for a WH’s physical validity.We also observe that the null energy condition(NEC)behaves negatively.Finally,for both models,we use the volume integral quantifier(VIQ)and Tolman-Oppenheimer-Volkoff(TOV)equation to determine how much exotic matter is needed near the WH throat and the stability of the WH.The extensive detailed discussions of the matter components have been done via graphical analysis.The obtained WH geometries meet the physically acceptable conditions for a stable wormhole.

Conformally symmetric wormhole solutions supported by non-commutative geometry in f(Q,T)gravity

This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian distributions.The primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian distributions.The resulting shape function satisfies all the necessary conditions for a traversable wormhole.Furthermore,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy conditions.Additionally,we explore the effect of anisotropy under Gaussian and Lorentzian distributions.Finally,we present our conclusions based on the obtained results.

Anisotropic quintessence compact star in f(T)gravity with Tolman–Kuchowicz metric potentials

To obtain analytically relativistic quintessence anisotropic spherical solutions in the f(T)paradigm is the primary objective of this paper.To do this,the pressure anisotropy condition is imposed,and we employ a metric potential of the Tolman–Kuchowicz(TK)type.We also suppose that our current model incorporates a quintessence field characterized by a parameterωq,in addition to the anisotropic matter distribution.In the presence of the parameterα,the field equations are modified by the choice of the f(T)function.The f(T)gravity parameterαadds new components to the basic physical characteristics,such as density,pressure,subliminal sound velocity,surface redshift,etc,of the present model.By selecting the compact star Her X-1 and varyingαfrom 0.5 to 2.5,we examined all the physical characteristics of the model parameter of the configuration.The graphical process demonstrates that a more compact item is produced with greater values ofα.The hydrostatic equilibrium condition of the model is discussed,as well as the mass-radius relationship for our current model is obtained.

Wormhole solutions under the effect of dark matter in f(R,L_(m))gravity

In the background of f(R,L_(m))gravity,this work investigates three distinct dark matter halo profiles to test the possibility of generalised wormhole geometry within the galactic halo regions.The current study aims to accomplish these goals by examining various dark matter profiles including universal rotation curves(URC),Navarro-Frenk-White(NFW)model-Ⅰ,and NFW model-Ⅱinside two distinct f(R,L_(m))gravity models.According to the f(R,L_(m))=R/2+L^(a)_(m)model,the dark matter(DM)halo density profiles produce suitable shape functions that meet all the necessary requirements for exhibiting the wormhole geometries with appropriate choice of free parameters.In addition,to examine DM profiles under the f(R,L_(m))=R/2+(1+λR)L_(m) model,we consider a specific shape function.Further,we observed that the derived solution from both two models violates the null energy constraints,confirming that the DM supports wormholes to maintain in the galactic halo.

阻断SP/NK1R信号轴可抑制小鼠黑色素瘤增殖

目的:探讨阻断SP/NK1R信号轴对小鼠黑色素瘤生长的影响及可能作用途径。方法:建立瞬时接种B16F10细胞形成原位黑色素瘤的小鼠模型,腹腔注射给予NK1R拮抗剂阿瑞匹坦(5 mg/kg)进行干预。给药5次后取小鼠胸腺、脾脏和皮肤黑色素瘤组织,计算各组小鼠体重变化、肿瘤增长变化、胸腺指数和脾脏指数;采用免疫荧光染色考察黑色素瘤组织中细胞增殖和凋亡情况;并观察肿瘤组织中浸润效应CD8 T细胞的表达情况。结果:给予阿瑞匹坦拮抗NK1R对各组小鼠体重没有明显影响,但能显著抑制原位黑色素瘤的增殖;阻断SP/NK1R信号轴能够引起小鼠胸腺指数显著升高,但对脾脏指数没有明显影响;免疫荧光染色结果显示给予阿瑞匹坦能够显著抑制黑色素瘤细胞在体内的增殖,并显著促进其凋亡;同时,拮抗NK1R能够显著增加肿瘤浸润效应CD8 T细胞的数目。结论:阻断SP/NK1R信号轴可以显著抑制小鼠中黑色素瘤细胞的增殖,并促进肿瘤细胞凋亡,这一作用可能是通过促进CD8 T细胞浸润,增强抗肿瘤免疫来实现的。