In this paper, we use a newly compiled sample of ultra-compact structure in radio quasars and strong gravitational lensing systems with quasars acting as background sources to constrain six spatially flat and non-flat cosmological models ($Λ$CDM, PEDE and DGP). These two sets of quasar data (the time-delay measurements of six strong lensing systems and 120 intermediate-luminosity quasars calibrated as standard rulers) could break the degeneracy between cosmological parameters ($H_0$, $Ω_m$ and $Ω_k$) and therefore provide more stringent cosmological constraints for the six cosmological models we study. A joint analysis of the quasar sample provides model-independent estimations of the Hubble constant $H_0$, which is strongly consistent with that derived from the local distance ladder by SH0ES collaboration in the $Λ$CDM and PEDE model. However, in the framework of a DGP cosmology (especially for the flat universe), the measured Hubble constant is in good agreement with that derived from the the recent Planck 2018 results. In addition, our results show that zero spatial curvature is supported by the current lensed and unlensed quasar observations and there is no significant deviation from a flat universe. For most of cosmological model we study (the flat $Λ$CDM, non-flat $Λ$CDM, flat PEDE, and non-flat PEDE models), the derived matter density parameter is completely consistent with $Ω_m\sim 0.30$ in all the data sets, as expected by the latest cosmological observations. Finally, according to the the statistical criteria DIC, although the joint constraints provide substantial observational support to the flat PEDE model, they do not rule out dark energy being a cosmological constant and non-flat spatial hypersurfaces.
We report a photoluminescence (PL) spectroscopy study of charge state control in single self-assembled InAs/GaAs quantum dots by applying electric and/or magnetic fields at 4.2 K. Neutral and charged exciton complexes were observed under applied bias voltages from −0.5 V to 0.5 V by controlling the carrier tunneling. The highly negatively charged exciton emission becomes stronger with increasing pumping power, arising from the fact that electrons have a smaller effective mass than holes and are more easily captured by the quantum dots. The integrated PL intensity of negatively charged excitons is affected significantly by a magnetic field applied along the sample growth axis. This observation is explained by a reduction in the electron drift velocity caused by an applied magnetic field, which increases the probability of non-resonantly excited electrons being trapped by localized potentials at the wetting layer interface, and results in fewer electrons distributed in the quantum dots. The hole drift velocity is also affected by the magnetic field, but it is much weaker.
We propose an improved method to determine the sound horizon in a cosmological model-independent way by using the latest observations of BAO measurements from DES, BOSS/eBOSS, and DESI surveys and gravitationally time-delay lensed quasars from H0LiCOW collaboration. Combining the 6$D_{\Delta t}$ plus 4$D_{d}$ measurements and the reconstructed BAO datasets, we obtain a model-independent result of $r_d=139.7^{+5.2}_{-4.5}$ Mpc, with the precision at the $\sim3.7\%$ level, which is in agreement with the result of Planck 2018 within $\sim1.7\sigma$ uncertainty. Our method is independent of cosmological parameters such as the Hubble constant, dark energy, (and, more importantly, does not involve the cosmic curvature when using the $D_d$ measurements of the lenses, and also avoids the obstacle of mass-sheet degeneracy in gravitational lensing). Meanwhile, it does not need to consider the Eddington relation with concerning the transformation of distance. Since only two types of data are considered, the contribution of each can be clearly understood. Our results also highlight the Hubble tension and may give us a better understanding of the discordance between the datasets or reveal new physics beyond the standard model.
The construction of 1,5-disubstituted 1,2,3-triazoles has been effected through the cascade dual C-N bond formation, N-N bond formation and an acyl migration-based C-C bond formation via the three-component reactions of enaminones, tosylhydrazine and primary amines. This metal- and azide-free, regioselective synthetic method proceeds in the presence of only molecular iodine.
Traditional metal-oxide semiconductor devices are inadequate for use in artificial neural networks (ANNs) owing to their high power consumption, complex structures, and difficult fabrication techniques. Resistive random access memory (RRAM) is a promising candidate for ANNs owing to its simple structure, low power consumption, and excellent compatibility with CMOS. Moreover, it can mimic synaptic functions because of its multilevel resistive switching (RS) behavior. Herein, we demonstrate highly uniform RS and a high on/off ratio of RRAM based on graphene oxide by embedding gold nanoparticles into the device. This allowed reliable multilevel storage. Further, multilevel RRAM based on spike-timing-dependent-plasticity learning rules was used for image pattern recognition. These findings may offer a route to develop reliable digital memristors for ANNs.
In this paper, the phase structure of the Hayward-AdS black hole (BH) is studied using shadow formalism. It has been found that the shadow radius is a monotonic function of the horizon radius and can therefore play an equivalent role to the horizon radius in characterizing the thermodynamics of Hayward-AdS BH. The thermodynamic phase transition (PT) of the Hayward-AdS BH is investigated with the shadow radius. It is shown that as the magnetic charge increases, the shadow radius becomes larger, while the coexistence temperature becomes lower. The thermal profile of the Hayward-AdS BH is established by combining the temperature diagram and the shadow cast diagram, which shows that for a fixed magnetic charge, the temperature of the Hayward-AdS BH increases with the pressure while the region of the thermal profile decreases with the pressure. In particular, the temperature of the Hayward-AdS BH follows an N-type change trend when it is smaller than the critical temperature. This imply that the BH shadow may be used to investigate the thermodynamics of the Hayward-AdS BH.
Context. The determination of the spatial geometry of the Universe plays an important role in modern cosmology. Any deviation from the cosmic curvature Ω K = 0 would have a profound impact on the primordial inflation paradigm and fundamental physics. Aims. In this paper, we carry out a systematic study of the prospect of measuring the cosmic curvature with the inspiral signal of supermassive black hole binaries (SMBHBs) that could be detected with TianQin. Methods. The study is based on a method that is independent of cosmological models. It extended the application of gravitational wave (GW) standard sirens in cosmology. By comparing the distances from future simulated GW events and simulated H ( z ) data, we evaluated whether TianQin produced robust constraints on the cosmic curvature parameter Ω k . More specifically, we considered three-year to ten-year observations of supermassive black hole binaries with total masses ranging from 10 3 M ⊙ to 10 7 M ⊙ . Results. Our results show that in the future, with the synergy of ten-year high-quality observations, we can tightly constrain the curvature parameter at the level of 1 σ Ω k = −0.002 ± 0.061. Moreover, our findings indicate that the total mass of SMBHB does influence the estimation of cosmic curvature, as implied by the analysis performed on different subsamples of gravitational wave data. Conclusions. Therefore, TianQin is expected to provide a more powerful and competitive probe of the spatial geometry of the Universe, compared to future spaced-based detectors such as DECIGO.
Long afterglow photocatalyst has shown the potential to support all-weather photocatalytic reactions. In this work, an Ag/Ca2Al2SiO7: Pr3+ (Ag/CASO: Pr3+) composite has been synthesized to enhance afterglow-driven photocatalytic activity. Ag...
Precipitation strengthening of silicides plays an important role in improving the creep resistance of high‐temperature titanium alloys. The oversize and concentrated silicides remarkably reduce the ductility of the alloys, which shorten the serving life of the key components in aerospace engines and gas turbines. To investigate the alloying effect on the stability of Ti 5 Si 3 , the enthalpy of solution for IIIB–VIB and IIIA–IVA elements in Ti 5 Si 3 , α matrix, and β phase are calculated and compared. It is proposed that Zr and Hf stabilize Ti 5 Si 3 and promote the nucleation and refinement of silicide particles. The β stabilizers and simple metals destabilize Ti 5 Si 3 and would suppress the precipitation of Ti 5 Si 3 .
Long distance communication protocols cannot ignore the existence of the Earth's gravitational field and its effects on quantum states. In this work, we show a very general method to consider the effects of the Earth's gravitational field on continuous-variable quantum key distribution protocols. Our results show that the Earth's gravitational field erodes the ability of the two parties to perform QKD in all the protocols. However, our findings also exhibit some interesting features, i.e., the key rates initially increase for a specific range of height parameter $h\simeq r_A/2$ and then gradually decrease with the increasing of the orbits of satellite $h$. A possible explanation is also provided in our analysis, considering the fact that gravitational frequency shift and special relativistic effects play different roles in the key rates. In addition, our findings show that the change in key rate effected by gravitational frequency shift can be determined at a level of $<1.0\%$ within the satellite height at geostationary Earth orbits. Our work could provide some interesting possibilities to reduce the loss key rate through the control of the orbital height of satellites.
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