Evolution of the strange-metal scattering in momentum space of electron-doped La2−xCexCuO4{\rm La}_{2-x}{\rm Ce}_x{\rm CuO}_4

The linear-in-temperature resistivity is one of the important mysteries in the strange metal state of high-temperature cuprate superconductors. To uncover this anomalous property, the energy-momentum-dependent imaginary part of the self-energy Im ${\rm \Sigma}(k, \omega)$ holds the key information. Here we perform systematic doping, momentum, and temperature-dependent angle-resolved photoemission spectroscopy measurements of electron-doped cuprate ${\rm La}_{2-x}{\rm Ce}_x{\rm CuO}_4$ and extract the evolution of the strange metal scattering in momentum space. At low doping levels and low temperatures, Im ${\rm\Sigma} \propto \omega$ dependence dominates the whole momentum space. For high doping levels and high temperatures, Im ${\rm\Sigma} \propto \omega^2$ shows up, starting from the antinodal region. By comparing with the hole-doped cuprates ${\rm La}_{2-x}{\rm Sr}_x{\rm CuO}_4$ and ${\rm Bi}_2{\rm Sr}_2{\rm CaCu}_2{\rm O}_8$, we find a dichotomy of the scattering rate exists along the nodal and antinodal direction, which is ubiquitous in the cuprate family. Our work provides new insight into the strange metal state in cuprates

Co-benefits for net carbon emissions and rice yields through improved management of organic nitrogen and water

Returning organic nutrient sources (for example, straw and manure) torice fields is inevitable for coupling crop–livestock production. However,an accurate estimate of net carbon (C) emissions and strategies tomitigate the abundant methane (CH4) emission from rice fields suppliedwith organic sources remain unclear. Here, using machine learning and aglobal dataset, we scaled the field findings up to worldwide rice fields toreconcile rice yields and net C emissions. An optimal organic nitrogen (N)management was developed considering total N input, type of organicN source and organic N proportion. A combination of optimal organic Nmanagement with intermittent flooding achieved a 21% reduction in netglobal warming potential and a 9% rise in global rice production comparedwith the business-as-usual scenario. Our study provides a solution forrecycling organic N sources towards a more productive, carbon-neutral andsustainable rice–livestock production system on a global scale

Analysis of conductance and interfacial polarisation behaviours of silicone rubber based on frequency domain spectroscopy

Abstract Silicone rubber (SR) is widely used for cable insulation and operates in multi‐stress coupling conditions. Its dielectric properties and ageing performance are the essential factors affecting cable operation. In this study, the frequency domain spectroscopy of unaged SR and SR aged under various conditions is measured. The dielectric responses before and after ageing are analysed in depth by the conjoint analysis via multiple complex planes (permittivity, conductivity, and modulus). Typical conductivity and interfacial polarisation properties, as well as property changes resulting from thermal and tensile ageing, are examined. Experimental results show that tensile ageing promotes conductance and interfacial polarisation, while thermal ageing shows the opposite effects. Based on the multi‐core model and charge carrier hopping transport model, thermal and tensile ageing mechanisms on the conductance and interfacial polarisation behaviours of SR are demonstrated. Both behaviours exhibit positively correlated changing characteristics, suggesting that the two behaviours may originate from a common process. The carrier transport process, promoted by the tensile effect and slightly suppressed by the thermal effect, is the primary factor and considered an important indicator to evaluate the dielectric properties of SR insulation

An integrated hydrodynamic model for runoff-generated debris flows with novel formulation of bed erosion and deposition

Debris flow is one of the most common geohazards in mountainous regions, posing significant threats to people, property and infrastructure. Among different types of debris flows, runoff-generated debris flows are attributed to rain storms, which provide abundant runoff that entrain large quantities of bed material, resulting in the formation of a solid-liquid current known as a debris flow. One of the keys to effectively simulating runoff-generated debris flows is modelling the erosion-deposition process. The commonly used approach for formulating erosion and deposition, although constrained by physics, suffers from a singularity in the presence of vanishing velocity, which poses a major challenge for practical applications. It is also argued that the deposition rate cannot be represented by simply reversing the sign of the erosion rate. To address these two issues, we have developed a depth-averaged debris flow model with a novel method of calculating the erosion-deposition rate. We have demonstrated that the singularity is due to the non-linear erosion-deposition term but quickly disappears while the flow converges to the equilibrium that is defined by the classic Takahashi's formula. To resolve the non-linearity and avoid the singularity, an implicit method within a Godunov-type finite volume framework has been proposed. An additional parameter is introduced to differentiate the erosion rate from the deposition rate. The model is validated against several test cases, including a real-world debris flow event. Satisfactory results are obtained, demonstrating the model's simulation capability and potential for wider applications such as risk assessment and impact-based early warning.</p