Three-Layered Atmospheric Structure in Accretion Disks Around Stellar-Mass Black Holes

Modeling of the x-ray spectra of the Galactic superluminal jet sources GRS 1915+105 and GRO J1655-40 reveal a three-layered atmospheric structure in the inner region of their accretion disks. Above the cold and optically thick disk of a temperature 0.2-0.5 keV, there is a warm layer with a temperature of 1.0-1.5 keV and an optical depth around 10. Sometimes there is also a much hotter, optically thin corona above the warm layer, with a temperature of 100 keV or higher and an optical depth around unity. The structural similarity between the accretion disks and the solar atmosphere suggest that similar physical processes may be operating in these different systems.Comment: 5 fives, 2 figures, 1 table. The online version of the paper in Science may be accessed through http://jet.uah.edu/~zhangsn/papers.htm

A facile approach to build Bi2O2CO3/PCN nanohybrid photocatalysts for gaseous acetaldehyde efficient removal

Constructing heterojunction between two semiconductors is a cost-effective pathway to fabricate efficient photocatalysts for environmental remediation and energy-related applications, which is with profound significance and high desirability to contemporary era. In this work, we demonstrate an extremely facile approach to couple bismuth subcarbonate with polymeric carbon nitride (denoted as BIOC@PCN) by ion exchange between home-made rose-like Bi2O2(OH)(NO3) (denoted as BION) and PCN bulks at 433 K solvothermal condition. PCN bulks play multi-roles in this ingenious one-pot method. Firstly, PCN bulks guarantee the negatively charged surface to anchor plentiful bismuth precursor salts. More importantly, solvothermal treatment affords a weak basic and sufficient CO32− ions environment to promote the following ion exchange reaction. The evolution of morphology, components and structure from rose-like BION to BIOC@PCN were symmetrically characterized by means of SEM, HR-TEM, XRD, FTIR, TG, UV–vis, BET-BJH and XPS. The as-prepared nanohybrid photocatalyst (0.5BIOC@PCN) presents optimal photocatalytic performance for gaseous acetaldehyde removal, which is showing 10, 6.5 and 2 times higher than that of the PCN-Bulk, BION and mechanical mixed BIOC/PCN counterparts, respectively. Transient photocurrent response and EPR results further verify the validity of the established heterojunction of BIOC@PCN in facilitating the separation of charge carriers. The performance improvement gains from the efficient separation of charge carriers in BIOC@PCN heterojunction, manifested by PL spectra, transient photocurrent response and EPR results. In this study, a facile and cost-effective approach to build PCN-based nanohybrid photocatalysts for gaseous acetaldehyde efficient removal was established

Quantum Neuronal Sensing of Quantum Many-Body States on a 61-Qubit Programmable Superconducting Processor

Classifying many-body quantum states with distinct properties and phases of matter is one of the most fundamental tasks in quantum many-body physics. However, due to the exponential complexity that emerges from the enormous numbers of interacting particles, classifying large-scale quantum states has been extremely challenging for classical approaches. Here, we propose a new approach called quantum neuronal sensing. Utilizing a 61 qubit superconducting quantum processor, we show that our scheme can efficiently classify two different types of many-body phenomena: namely the ergodic and localized phases of matter. Our quantum neuronal sensing process allows us to extract the necessary information coming from the statistical characteristics of the eigenspectrum to distinguish these phases of matter by measuring only one qubit. Our work demonstrates the feasibility and scalability of quantum neuronal sensing for near-term quantum processors and opens new avenues for exploring quantum many-body phenomena in larger-scale systems.Comment: 7 pages, 3 figures in the main text, and 13 pages, 13 figures, and 1 table in supplementary material

Experimental quantum computational chemistry with optimised unitary coupled cluster ansatz

Simulation of quantum chemistry is one of the most promising applications of quantum computing. While recent experimental works have demonstrated the potential of solving electronic structures with variational quantum eigensolver (VQE), the implementations are either restricted to nonscalable (hardware efficient) or classically simulable (Hartree-Fock) ansatz, or limited to a few qubits with large errors for the more accurate unitary coupled cluster (UCC) ansatz. Here, integrating experimental and theoretical advancements of improved operations and dedicated algorithm optimisations, we demonstrate an implementation of VQE with UCC for H_2, LiH, F_2 from 4 to 12 qubits. Combining error mitigation, we produce high-precision results of the ground-state energy with error suppression by around two orders of magnitude. For the first time, we achieve chemical accuracy for H_2 at all bond distances and LiH at small bond distances in the experiment. Our work demonstrates a feasible path towards a scalable solution to electronic structure calculation, validating the key technological features and identifying future challenges for this goal.Comment: 8 pages, 4 figures in the main text, and 29 pages supplementary materials with 16 figure

Bonding Performance and Evaluation of Basalt Fiber Asphalt Macadam Seal

To broaden the application of the basalt fiber in the preventive maintenance of asphalt pavement, this study investigated the bonding performance and evaluated the comprehensive performance of the basalt fiber asphalt macadam seal. Firstly, different types of basalt fiber asphalt macadam seal were prepared. The influences of content and length of the basalt fiber and dosage of emulsified asphalt on the bonding performance of the asphalt macadam seal were analyzed and compared. Next, by using the efficacy coefficient method, comprehensive performance considering both mechanical and economic characteristics of the basalt fiber asphalt macadam seal was evaluated. After that, reasonable content of each material was determined. Finally, the strengthening mechanism of the fiber on the bonding performance of macadam seals was revealed from a microscopic view. The results showed that compared with the ordinary asphalt macadam seal, the loss aggregate rate of the basalt fiber asphalt macadam seal was 11.0–30.5% lower, and the pull-out strength, shear strength, and torsional shear strength were 11.7–16.3%, 9.7–22.4%, and 4.2–20.6% higher, respectively. Considering the bonding performance and economic benefits, the optimal amount of emulsified asphalt and basalt fiber was 1.6 kg/m2 and 70 g/m2, respectively. Basalt fiber increased the cohesion of the asphalt material and improved the bonding performance of asphalt macadam seals through formation of the three-dimensional network structure. This study can provide reference to the application of basalt fibers in asphalt pavement maintenance

Atomically dispersed Fe-heteroatom (N, S) bridge sites anchored on carbon nanosheets for promoting oxygen reduction reaction

Single Fe atom dispersed carbon nanostructures show promising oxygen reduction reaction (ORR) activities for renewable energy applications. Nevertheless, the microenvironment of the single Fe atoms needs to be further engineered to optimize the catalytic performance, which is challenging. In this work, we develop a NaCl-template pyrolysis method to fabricate single Fe atom catalysts with atomically dispersed Fe-heteroatom (N, S) bridge sites anchored on carbon nanosheets. The N and S coordinated Fe atomic sites (FeN3S) are found to induce charge redistribution, lowering the binding strength of oxygenated reaction intermediates and leading to fast reaction kinetics and good oxygen reduction activity. Our work provides an effective method to regulate the microenvironment of single-atom catalysts for optimizing electrocatalytic performance.The authors acknowledge the financial support from the Research Foundation of China Postdoctoral Science (2018M643177), National Natural Science Foundation of China (21972094), Guangdong Special Support Program, Pengcheng Scholar program, Shenzhen Peacock Plan (KQTD2016053112042971), and the Science and Technology Planning Project of Shenzhen of China (JCYJ20190808141809282). The authors also acknowledge the support of the 1W1B beamline of Beijing Synchrotron radiation facility (BSRF)