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Bioluminescence (BL) is an excellent optical readout for bioassays and molecular imaging. Herein, we accomplished new near infrared bioluminescence resonance energy transfer (NIR-BRET) templates for monitoring molecular events in cells with higher sensitivity. We first identified the best resonance energy donor for the NIR-BRET templates through the characterization of many coelenterazine (CTZ)–marine luciferase combinations. As a result, we found that NLuc–DBlueC and ALuc47–nCTZ combinations showed luminescence in the blue emission wavelength with excellent BL intensity and stability, for example, the NLuc–DBlueC and ALuc47–nCTZ combinations were 17-fold and 22-fold brighter than their second highest combinations, respectively, and were stably bright in living mammalian cells for at least 10 min. To harness the excellent BL properties to the NIR-BRET systems, NLuc and ALuc47 were genetically fused to fluorescent proteins (FPs), allowing large “blue-to-red” shifts, such as LSSmChe, LSSmKate2, and LSSmNep (where LSS means Large Stokes Shift). The excellent LSSmNep–NLuc combination showed approximately 170 nm large resonance energy shift from blue to red. The established templates were further utilized in the development of new NIR-BRET systems for imaging steroid hormone activities by sandwiching the ligand-binding domain of a nuclear receptor (NR-LBD) between the luciferase and the FP of the template. The NIR-BRET systems showed a specific luminescence signal upon exposure to steroid hormones, such as androgen, estrogen, and cortisol. The present NIR-BRET templates are important additions for utilizing their advantageous imaging of various molecular events with high efficiency and brightness in physiological samples.

A key discovery of this study is the strong correlation (r = 0.96) between excitation and emission maxima across chemically distinct clusteroluminogens. All 157 evaluated peaks fall along a single regression line (Ex = 0.844 Em − 12 nm), a pattern that was not valid for conventional fluorophores. This suggests a general principle of clusteroluminescence. We show that in lignocellulosic materials, peak positions reflect chemical interactions: isolated lignin and cellulose showed short excitation and emission wavelengths, while native wood exhibited longer wavelengths. Fungal or photoinduced degradation led to a further red-shift. These effects are attributed to increased molecular heterogeneity, reducing the effective energy gap within the lignocellulosic complex. We conclude that the spectral position reflects the degree of molecular interaction rather than the chemical structure of individual molecules. It may serve as a novel analytical parameter for assessing purity and degradation in a wide range of polymers.

We have developed a Bianchi I cosmological model of the universe in f ( R ,  T ) gravity theory which fit good with the present-day scenario of accelerating universe. The model displays transition from deceleration in the past to the acceleration at the present. As in the Λ CDM model, we have defined the three energy parameters Ω m , Ω μ and Ω σ such that Ω m + Ω μ + Ω σ = 1. The parameter Ω m is the matter energy density (baryons + dark matter), Ω μ is the energy density associated with the Ricci scalar R and the trace T of the energy momentum tensor and Ω σ is the energy density associated with the anisotropy of the universe. We shall call Ω μ dominant over the other two due to its higher value. We find that the Ω μ and the other two in the ratio 3:1. 46 Hubble OHD data set is used to estimate present values of Hubble H 0 , deceleration q 0 and jerk j parameters. 1 σ , 2 σ and 3 σ contour region plots for the estimated values of parameters are presented. 580 SNIa supernova distance modulus data set and 66 pantheon SNIa data which include high red shift data in the range 0 ≤ z ≤ 2.36 have been used to draw error bar plots and likelihood probability curves for distance modulus and apparent magnitude of SNIa supernova’s. We have calculated the pressures and densities associated with the two matter densities, viz. p μ , ρ μ , p m and ρ m , respectively. The present age of the universe as per our model is also evaluated, and it is found at par with the present observed values.

Einstein–Newcomb–de Sitter (ENdS) space is de Sitter’s modification of spherical space used by Einstein in his first cosmological model paper published in 1917. The modification by de Sitter incorporated the topological identification of antipodal points in space previously proposed by Newcomb in 1877. De Sitter showed that space topologically modified in this way (called elliptical or projective space) satisfies Einstein’s field equations. De Sitter also found that in a space with constant positive curvature, spectral lines of remote galaxies would be red-shifted (called the de Sitter effect). However, de Sitter’s formulae relating distances to red shifts do not satisfy observational data. The likely reason for this mismatch is that de Sitter mainly focused on space curvature and ignored the identification of antipodal points. Herein, we demonstrate that it is this particular feature that allows an almost perfect fit of the ENdS-based cosmological model to observational data. We use 1701 sources from the type Ia supernovae data sample called Pantheon+, which was previously used to fit the ΛCDM model. ΛCDM and ENdS diverge in their predictions for red shifts exceeding z∼2.3. Since there are no available type Ia supernovae (SNe) data for higher red shifts, both models can be validated by using an additional sample of 193 gamma-ray bursts (GRBs) spanning red shifts up to z∼8. This validation shows that the minimum χ2 for the SNe+GRBs sample is about 2.7% smaller for the ENdS space model than for the ΛCDM model.

We consider a free-falling observer who crosses the event horizon in the Schwarzschild background. In the course of this fall, he/she can receive signals from an object (like a star surface) that emits radiation. We study how the frequency received by an observer changes depending on the proper time on his/her trajectory. The scenarios are classified depending on whether the frequency is infinite, finite or zero near the singularity and the horizon. This depends crucially on the angular momenta of an observer and a photon. In this work we consider also emission process, and, as we show, conditions of emission strongly influence parameters of a photon, and thus received frequency. As one of our main results, we present numerical calculations showing evolution of the received frequency during the process of diving into a black hole, depending on parameters of an observer and emitter. We also analyze how a falling observer will see a night sky as he/she approaches the singularity. We show that there appear several blind zones, which were not analyzed previously.

A new strange star model based on Durgapal IV metric (Durgapal in J. Phys. A 15:2637, 1982) is presented here. Here we have applied a specific method to study the inner physical properties of the compact objects 4U 1702-429, 2A 1822-371, PSR J1756-2251, PSR J1802-2124 and PSR J1713+0747. The main objective of our study is to determine central density (ρ0\\(\\rho _{0}\\)), surface density (ρb\\(\\rho _{b}\\)), central pressure (p0\\(p_{0}\\)), surface redshift (Zs\\(Z_{s}\\)), compactness and radius. Further we perform different tests to study the stability of our model and finally we are able to give an equation based on pressure and density i.e. probable equation of state (EoS) which has an important significances in the field of Astrophysics.

Numerous studies have been carried out on different aspects of the light from summer-active fireflies. Characteristics of this light have led to very interesting conclusions on the chemiluminescence reaction as well as on the nature of the light from live fireflies. Here we present a first report on bioluminescence emissions from a newly found winter-active Indian species of firefly Diaphanes sp. The steady-state emission spectrum from this species comes out to be apparently similar to those from the other two Indian summer species, Luciola praeusta and Asymmetricata circumdata: asymmetric in nature with a little bit of change in the position of the peak wavelength and in the width of the full width at half maximum. An increase in temperature to approximately 28°C causes a red-shift in the peak wavelength, which probably indicates denaturation of the enzyme luciferase in the live, flashing condition. Emissions in the time domain reveal that the light is never completely off – it decreases in intensity to a low value, sometimes very close to zero, and then increases – a characteristic unheard-of till date. Flash durations are considerably longer than those from the two Indian summer species; those become shorter at about 28°C and increase to noticeably larger values at higher temperatures.

We describe a simple method for the preparation of gold-decorated silica (SiO 2 ) nanoparticles (NPs) by the in situ precipitation method using simple BH 4 − ions reduction as a procedure, where BH 4 − ions are adsorbed onto PEI-functionalized SiO 2 NPs for stabilizing and reducing gold ions onto PEI-SiO 2 surface in water under ambient conditions. The result was 3-nm gold nanoshell NPs attached to SiO 2 core (~ 75 nm) with a surface plasmon resonance (SPR) at ~ 680 nm. SPR band is associated with Au NP aggregates that arise from strong interparticle interaction. This is an alternative to the gold-seeding methods and the use of anionic gold species for the obtention of gold-decorated SiO 2 NPs with an important red-shift in UV–Vis absorption and with potential applications in biosensors and photothermal therapy.

The development of Geometric theories of gravitation and the application of the Dynamics of General Relativity (GR) is the mainstream approach of gravitational field. Besides, the Generalized Special Relativity (GSR) contains the fundamental parameter (ξI) of Theories of Physics (TPs). Thus, it expresses at the same time Newtonian Physics (NPs) for ξI→ 0 and Special Relativity (SR) for ξI=1. Moreover, the weak Equivalence Principle (EP) in the context of GSR, has the interpretation: mG=m, where mG and m are the gravitational mass and the inertial rest mass, respectively. In this paper, we bridge GR with GSR. This is achieved, by using a GSR-Lagrangian, which contains the corresponding GR-proper time. Thus, we obtain a new central scalar GSR-gravitational generalized potential V=V(k,l,r,r_dot,ϕ_dot), where k=k(ξI), l=l(ξI), r is the distance from the center of gravity and r_dot, ϕ_dot are the radial and angular velocity, respectively. The replacement k=1 and l=ξI2 makes the above GSR-potential equivalent to the original Schwarzschild Metric (SM). Thus, it explains the Precession of Mercury's Perihelion (PMP), Gravitational Deflection of Light (GDL), Gravitational Red Shift (GRS) etc, by using SR and/or NPs. The procedure described in this paper can be applied to any other GR-spacetime metric, in order to find out the corresponding GSR-gravitational potential. So, we also use the GR-proper time of the 3rd Generalized Schwarzschild Metric (3GSM) and we obtain the central scalar GSR-gravitational potential V=V(a,k,l,r_dot,ϕ_dot), where a=a(r). The combination of the above with MOND interpolating functions, or distributions of Dark Matter (DM) in galaxies, provides the functions corresponding a=a(r). Thus, we obtain a new GSR-Gravitational field, which explains the PMP, GDL, GRS as well as the Rotation Curves in Galaxies, eliminating the corresponding DM.

In this article we propose a model for the Pulsar J0348+0432 (Antoniadis et al. in Science 340:1233232, 2013 ) in a compact relativistic binary. Here we investigate the physical properties of the Pulsar J0348+0432 by using the Finch and Skea (Class. Quantum Gravity 4:467, 1989 ) metric. Using our model, we evaluate central density ( ρ 0 ), surface density ( ρ b ), central pressure ( p 0 ), surface redshift ( Z s ) and probable radius of the above mentioned compact object, which is very much consistent with reported data. We also obtain a possible equation of state (EoS) of the pulsar which is physically acceptable.