Search

Nanobubbles are an important means to enhance the flotation of fine refractory minerals. Generally, nanobubbles are preferentially adsorbed on mineral surfaces, which increases the hydrophobicity of the surfaces. For flake graphite ore, nanobubbles coated on graphite surfaces reduce the thickness of the hydrated film on the mineral surface and increase its hydrophobicity. In comparative experiments performed here, short flotation circuits of small flake graphite coated with nanobubbles achieved a 92.81% average fixed carbon grade of graphite concentrate, whereas conventional flotation circuits achieved an average of 88.15%. In addition, the concentrate recovery of short flotation circuits with nanobubbles was higher than that of conventional flotation circuits. This result shows that nanobubbles enhanced graphite particle flotation. Further, in this process, reducing the grinding duration is beneficial to avoid the overgrinding of concentrate, maintain the flake scale size of graphite, and improve the grade of the graphite concentrate. [ABSTRACT FROM AUTHOR]

Quantum error correction (QEC) aims to protect logical qubits from noises by using the redundancy of a large Hilbert space, which allows errors to be detected and corrected in real time1. In most QEC codes2–8, a logical qubit is encoded in some discrete variables, for example photon numbers, so that the encoded quantum information can be unambiguously extracted after processing. Over the past decade, repetitive QEC has been demonstrated with various discrete-variable-encoded scenarios9–17. However, extending the lifetimes of thus-encoded logical qubits beyond the best available physical qubit still remains elusive, which represents a break-even point for judging the practical usefulness of QEC. Here we demonstrate a QEC procedure in a circuit quantum electrodynamics architecture18, where the logical qubit is binomially encoded in photon-number states of a microwave cavity8, dispersively coupled to an auxiliary superconducting qubit. By applying a pulse featuring a tailored frequency comb to the auxiliary qubit, we can repetitively extract the error syndrome with high fidelity and perform error correction with feedback control accordingly, thereby exceeding the break-even point by about 16% lifetime enhancement. Our work illustrates the potential of hardware-efficient discrete-variable encodings for fault-tolerant quantum computation19.The lifetime of a qubit in a circuit quantum electrodynamics architecture can exceed the break-even point through quantum error correction, representing a key step towards scalable quantum computing. [ABSTRACT FROM AUTHOR]

Coal gangue, a by-product produced during the coal processing, has a serious impact on the environment. Using coal gangue as a fertilizer has been proven helpful in potentially reducing its environmental impact and improving its value. In this study, the formation mechanism and influencing factors of coal-gangue-based silicon fertilizer was studied using XRD and FT-IR measurement technologies. The results showed that the layered structure of coal gangue was severely damaged above 600 ℃, where the kaolin began to transform into metakaolin. When CaCO3 alone was added, CaCO3 mainly played a catalytic role, forming only a small amount of calcium silicate with available-Si content below 12.60%. When corn stalk powder alone was added, the oxides of the corn stalk ash participated in the chemical reaction involving coal gangue, forming nepheline (K(Na, K)3Al4Si4O16) and other silicates with available-Si content of 14.56%. When coal gangue, CaCO3, and corn stalk powder were mixed and calcined, the available-Si content was as high as 22.97% under the synergistic effect of CaCO3 and corn stalk powder; the concentration of toxic metals and ions was below 52.87 mg/kg. The prepared silicon fertilizer can reduce the pollution of coal gangue and meet the agricultural needs of China. [ABSTRACT FROM AUTHOR]

In isogeometric analysis (IGA), the boundary representation of computer-aided design (CAD) and the tensor-product non-uniform rational B-spline structure make the analysis of three-dimensional (3D) problems with irregular geometries difficult. In this paper, an IGA method for complex models is presented by reconstructing analysis-suitable models. The CAD model is represented by boundary polygons or point cloud and is embedded into a regular background grid, and a model reconstruction method is proposed to obtain the level set function of the approximate model, which can be directly used in IGA. Three 3D examples are used to test the proposed method, and the results demonstrate that the proposed method can deal with complex engineering parts reconstructed by boundary polygons or point clouds. [ABSTRACT FROM AUTHOR]

Einstein–Podolsky–Rosen (EPR) steering is a useful resource for secure quantum information tasks. It is crucial to investigate the effect of inevitable loss and noise in quantum channels on EPR steering. We analyze and experimentally demonstrate the influence of purity of quantum states and excess noise on Gaussian EPR steering by distributing a two-mode squeezed state through lossy and noisy channels, respectively. We show that the impurity of state never leads to sudden death of Gaussian EPR steering, but the noise in quantum channel can. Then we revive the disappeared Gaussian EPR steering by establishing a correlated noisy channel. Different from entanglement, the sudden death and revival of Gaussian EPR steering are directional. Our result confirms that EPR steering criteria proposed by Reid and I. Kogias et al. are equivalent in our case. The presented results pave way for asymmetric quantum information processing exploiting Gaussian EPR steering in noisy environment. [ABSTRACT FROM AUTHOR]

The novel coronavirus disease 2019 (COVID-19) was first reported in Wuhan, China, where the initial wave of intense community transmissions was cut short by interventions. Using multiple data sources, here we estimate the disease burden and clinical severity by age of COVID-19 in Wuhan from December 1, 2019 to March 31, 2020. Our estimates account for the sensitivity of the laboratory assays, prospective community screenings, and healthcare seeking behaviors. Rates of symptomatic cases, medical consultations, hospitalizations and deaths were estimated at 796 (95% CI: 703–977), 489 (472–509), 370 (358–384), and 36.2 (35.0–37.3) per 100,000 persons, respectively. The COVID-19 outbreak in Wuhan had a higher burden than the 2009 influenza pandemic or seasonal influenza in terms of hospitalization and mortality rates, and clinical severity was similar to that of the 1918 influenza pandemic. Our comparison puts the COVID-19 pandemic into context and could be helpful to guide intervention strategies and preparedness for the potential resurgence of COVID-19. Here the authors analyze disease burden and clinical severity of COVID-19 during the first wave in Wuhan, China in comparison to past influenza virus pandemics and COVID-19 in the US and Canada. These estimates of symptomatic cases, medical consultations, hospitalizations and deaths should guide preparedness for this disease. [ABSTRACT FROM AUTHOR]

This article reviews state-of-the-art numerical techniques for fluid–structure interaction (FSI) of full-scale wind-turbine systems. Simulation of floating wind turbines subjected to combined wind-flow and ocean-wave forcing, and modeling of high-cycle fatigue failure of blades due to long-term cyclic aerodynamic loading, are the focal points of this article. Computational techniques including advanced structural modeling based on Isogeometric Analysis, free-surface FSI, and fatigue-damage modeling, are presented. Representative computational examples involving land-based and floating offshore wind-turbine designs illustrate the versatility and power of the computational methods developed. [ABSTRACT FROM AUTHOR]

This manuscript presents the experimental investigations on the seismic behavior of precast grouted sleeve column-to-foundation connections. Six full-scale specimens were constructed with varying longitudinal reinforcement ratios and stirrup ratios. Four specimens were precast with grouted sleeve connections. Two cast-in-place reference specimens were equivalent in design with the precast ones, but only without the grouted sleeve connections. Vertical compression ratio of approximately 0.41 was applied for use in high seismic regions. Damage states, load-carrying capacity, ductility, energy dissipation and strain distributions of the specimens are investigated and are compared with the cast-in-place reference specimens. The test results demonstrate that the sleeve connection exhibited comparable lateral deformation capacity and ductility but lower strength capacity compared to the cast-in-place reference specimens. Among the precast specimens, the increase in stirrup ratio slightly increased both the yield and the ultimate strength. The increase in longitudinal reinforcement ratio showed greater effects by considerably raising the ultimate strength, while increasing the yield strength marginally. [ABSTRACT FROM AUTHOR]

Understanding the distribution of quantum entanglement over many parties is a fundamental challenge of quantum physics and is of practical relevance for several applications in the field of quantum information. The Fisher information is widely used in quantum metrology since it is related to the quantum gain in metrology measurements. Here, we use methods from quantum metrology to microscopically characterize the entanglement structure of multimode continuous-variable states in all possible multi-partitions and in all reduced distributions. From experimentally measured covariance matrices of Gaussian states with 2, 3, and 4 photonic modes with controllable losses, we extract the metrological sensitivity as well as an upper separability bound for each partition. An entanglement witness is constructed by comparing the two quantities. Our analysis demonstrates the usefulness of these methods for continuous-variable systems and provides a detailed geometric understanding of the robustness of cluster-state entanglement under photon losses. Quantum metrology: Characterising entanglement An approach for experimentally characterising the structure of quantum entanglement over photonic modes is demonstrated. One of the most peculiar phenomenon of quantum mechanics is entanglement, where a quantum entangled state is shared over many parties. Despite playing a central role in quantum metrology and quantum computing, it's extremely challenging to experimentally characterize how entanglement is distributed. An international team of researchers led by Xiaolong Su from Shanxi University now demonstrate that squeezing coefficients and the Fisher information can be used to characterise entangled states of photonic modes. Whilst this approach can only be applied to certain systems, it may be possible to extend and generalize to others, which could help in understanding and developing a range of quantum technologies. [ABSTRACT FROM AUTHOR]

A quantum communication network can be constructed by distributing a multipartite entangled state to space-separated nodes. Entangled optical beams with highest flying speed and measurable brightness can be used as carriers to convey information in quantum communication networks. Losses and noises existing in real communication channels will reduce or even totally destroy entanglement. The phenomenon of disentanglement will result in the complete failure of quantum communication. Here, we present the experimental demonstrations on the disentanglement and the entanglement revival of tripartite entangled optical beams used in a quantum network. We experimentally demonstrate that symmetric tripartite entangled optical beams are robust in pure lossy but noiseless channels. In a noisy channel, the excess noise will lead to the disentanglement and the destroyed entanglement can be revived by the use of a correlated noisy channel (non-Markovian environment). The presented results provide useful technical references for establishing quantum networks. [ABSTRACT FROM AUTHOR]