Superconductivity in trilayer nickelate La4Ni3O10 under pressure

Nickelates gained a great deal of attention due to their similar crystal and electronic structures of cuprates over the past few decades. Recently, superconductivity with transition temperature exceeding liquid-nitrogen temperature is discovered in La3Ni2O7, which belong to the Ruddlesden-Popper (RP) phases Lan+1NinO3n+1 with n = 2. In this work, we go further and find pressure-induced superconductivity in another RP phase La4Ni3O10 (n = 3) single crystals. Our angle-resolved photoemission spectroscopy (ARPES) experiment suggest that the electronic structure of La4Ni3O10 is very similar to that of La3Ni2O7. We find that the density-wave like anomaly in resistivity is progressively suppressed with increasing pressure. A typical phase diagram is obtained with the maximum Tc of 21 Kelvin. Our study sheds light on the exploration of unconventional superconductivity in nickelates.Comment: 16 pages, 5 figure

Coupling Mesoscopic Boltzmann Transport Equation and Macroscopic Heat Diffusion Equation for Multiscale Phonon Heat Conduction

International audiencePhonon heat conduction has to be described by the Boltzmann transport equation (BTE) when sizes or sources are comparable to or smaller than the phonon mean free paths (MFPs). When domains much larger than MFPs are to be treated or when regions with large and small MFPs coexist, the computation time associated with full BTE treatment becomes large, calling for a multiscale strategy to describe the total domain and decreasing the computation time. Here, we describe an iterative method to couple the BTE, under the Equation of Phonon Radiative Transfer approximation solved by means of the deterministic Discrete Ordinate Method, to a Finite-Element Modelling commercial solver of the heat equation. Small-size elements are embedded in domains where the BTE is solved, and the BTE domains are connected to a domain where large-size elements are located and where the heat equation is applied. It is found that an overlapping zone between the two types of domains is required for convergence, and the accuracy is analysed as a function of the size of the BTE domain. Conditions for fast convergence are discussed, leading to the computation time being divided by more than five on a study case in 2D Cartesian geometry. The simple method could be generalized to other types of solvers of the Boltzmann and heat equations

A Progressive Combined Variable Selection Method for Near-Infrared Spectral Analysis Based on Three-Step Hybrid Strategy

A specific variable selection method was proposed based on a three-step hybrid strategy for near-infrared spectral analysis. By analyzing functions of each step and characteristics of various variable selection methods, synergy interval partial least squares, iterative variable subset optimization, and bootstrapping soft shrinkage were chosen for three steps. To test the effect of the three-step hybrid method, it was applied to corn and soil spectral data and compared to other common methods. Results for oil content in corn data showed that the three-step hybrid variable selection method selected 1% variables of full spectrum, calibration determination coefficient, and prediction determination coefficient reached 0.998 and 0.993 where the explained variance was increased by 27.30%. It could effectively extract variables related to the tested substance and provide a new variable selection method for near-infrared spectral analysis

Evaluation of Geomembrane Effect Based on Mobilized Shear Stress due to Localized Sinking

Installing geosynthetic reinforcement at the bottom of the embankment will provide positive support for subgrade stability and settlement control, if there is a void or a weak foundation. In routine design work, the geomembrane effect must be well estimated and the tensile strain should be precisely predicted. Conventional analytical methods often adopt the limit state method to calculate the overlying load on the deflected geosynthetic. However, this assumption does not necessarily apply to all conditions, especially when the foundation soil can provide certain resistance. In this study, a semiempirical prediction method for evaluating the geomembrane effect of the basal reinforcement was proposed, and an iterative solution for calculating tensile strains of a deflected geosynthetic was deduced. In derivation, a virtual inclined slip surface and interaction between the geosynthetic and soil were quantitatively evaluated by coupling the arching effect and the geomembrane effect. Moreover, the development of shear stress along the slip surface can be considered, as well as different segments of the basal reinforcement. Then, the proposed method was validated by two large-scale experiments. Comparison of the results of this method with measurements and results of other analytical models confirmed that this analytical method can take good care of the varying process of the localized sinking, regarding the overlying loads on the geosynthetic and the subsequent tensile strains

Low-temperature catalytic performance for oxidative dehydrogenation of propane on nanosized Ti(Zr)-Ni-O prepared by modified sol-gel method

Nanosized Ti(Zr)-Ni-O prepared by modified sol-gel method exhibited good low-temperature catalytic performance: 11.5% yield with 48% selectivity towards propene and 10.3% yield are obtained on Ti-Ni-O and Zr-Ni-O, respectively, at 275 degrees C for oxidative dehydrogenation of propane to propene. SEM and XRD results indicated that the Ti(Zr)-Ni-O nanoparticles were well-distributed and of typical diameter ca. 7 mm. The lattice parameters of the obtained nanostructured Ti(Zr)-Ni-O catalysts increased distinctly and there were stronger interaction between TiO2/ZrO2 and NiO. The interaction effectively restrains the deep oxidation of propane and leads to the increasing propene selectivity. (c) 2005 Elsevier B.V. All rights reserved

Low thermal expansion metal composite-based heat spreader for high temperature thermal management

The electronic industry is facing pressing needs for cooling system with high-performance in heat transfer and matched coefficient of thermal expansion (CTE) with the chips. Metal composite materials (MCMs) with low CTE can be used in cooling chips to overcome the thermal expansion mismatch between the cooling substrate and chips. However, low thermal conductivity of MCMs limits their application in electronic cooling systems. Increasing the percentage of components with high thermal conductivity can enhance the thermal conductivity of MCMs, but it often leads to increase CTE as well. Here, we demonstrate that vapor–liquid phase change can improve the heat transfer performance of tungsten-copper (W-Cu) alloy-based MCMs while maintain their low CTEs. Such strategy reduces the maximum temperature and thermal resistance of MCMs, and also allows for heat spreading from concentrated heat source with high power density. The W-Cu alloy-based vapor chamber (VC) has low thermal resistance of 0.38 K/W at 100 W and high lateral thermal conductivity of ~1727 W/(m·K). The W-Cu alloy-based VC can be readily integrated with the chip and heat sink to serve as cooling substrates for dissipating the heat and simultaneously lowering the thermal expansion mismatch by using its high thermal conductivity and low CTE

Quasi-ballistic thermal transport and temperature jumps in nanostructures

International audienc

Quasi-ballistic thermal transport and temperature jumps in nanostructures

International audienc

Breaking the chain in organ failure: Role of umbilical cord and bone marrow derived mesenchymal stem cells in treatment of severe acute pancreatitis

Background: Previous studies showed that MSCs could mitigate damage in the pancreas during acute pancreatitis (AP). However, acute mortality associated with AP was more often a result of persistent failure of remote organs, rather than local damage, especially in severe acute pancreatitis (SAP), and the effect of MSCs may vary depending on their origin. Methods: An SAP model was induced in 8-week C57BL/6 J male mice by retrograde injection of 5 % sodium taurocholate solution through the bile duct. SAP mice were divided into the SAP group, UC-MSCs group, and BMSCs group, which were treated with saline, 1 × 106 UC-MSCs, and 1 × 106 BMSCs respectively, through the tail vein. After treatment, serum markers, inflammation, and morphology were assessed in the pancreas, kidneys, lungs, and hearts. Results: MSCs infusion ameliorated the systemic inflammatory response in SAP mice. In the MSCs-treated SAP mice, local tissue injury and inflammation response in the pancreas were alleviated. But more importantly, the renal and lung injury were all significantly and drastically mitigated, and the levels of pro-inflammatory factors such as IL-6, MCP-1, IL-1β, and TNF-α in the kidney, lung and heart were sharply decreased. In terms of origin, UC-MSCs exhibited superior efficacy compared with BMSCs. Furthermore, compared to the normal control mice, UC-MSCs showed an earlier appearance, higher distribution densities, and longer duration of presence in the injured tissue. Conclusions: This study provides compelling evidence supporting the therapeutic potential of MSCs in SAP treatment and particularly their ability to mitigate multi-organ failure. Our results also suggested that UC-MSCs may offer greater advantages over BMSCs in SAP therapy