Predicted superconductivity and superionic state in the electride Li5_5N under high pressure

Recently, electrides have received increasing attention due to their multifunctional properties as superconducting, catalytic, insulating, and electrode materials, with potential to offer other performance and possess novel physical states. This work uncovers that Li$_5$N as an electride possess four novel physical states simultaneously: electride state, super-coordinated state, superconducting state, and superionic state. By obtaining high-pressure phase diagrams of the Li-N system at 150-350 GPa using a crystal structure search algorithm, we find that Li$_5$N can remain stable as P6/mmm structure and has a 14-fold super-coordination number, as verified by Bader charge and electron localization function analysis. Aditionally, we find that its superconducting transition temperature decreases continuously with increasing pressure, contrary to the behavior of most high-pressure superconducting materials. Its superconducting transition temperature reaches the highest among all known electride at 150 GPa (Tc = 48.97 K). Besides, Li$_5$N exhibits the superionic state at 3000 K, in which N atoms act like solid, while some Li atoms flow like liquid. The above results are further verified at a macroscopic level by using deep learning potential molecular dynamics simulations

Aeroelastic two-level optimization for preliminary design of wing structures considering robust constraints

AbstractAn aeroelastic two-level optimization methodology for preliminary design of wing structures is presented, in which the parameters for structural layout and sizes are taken as design variables in the first-level optimization, and robust constraints in conjunction with conventional aeroelastic constraints are considered in the second-level optimization. A low-order panel method is used for aerodynamic analysis in the first-level optimization, and a high-order panel method is employed in the second-level optimization. It is concluded that the design of the abovementioned structural parameters of a wing can be improved using the present method with high efficiency. An improvement is seen in aeroelastic performance of the wing obtained with the present method when compared to the initial wing. Since these optimized structures are obtained after consideration of aerodynamic and structural uncertainties, they are well suited to encounter these uncertainties when they occur in reality

Efficient hybrid algorithms to solve mixed discrete-continuous optimization problems: A comparative study

Purpose: – In real world cases, it is common to encounter mixed discrete-continuous problems where some or all of the variables may take only discrete values. To solve these non-linear optimization problems, it is very time-consuming in use of finite element methods. The purpose of this paper is to study the efficiency of the proposed hybrid algorithms for the mixed discrete-continuous optimization, and compares it with the performance of Genetic Algorithms (GA). Design/methodology/approach: – In this paper, the enhanced multipoint approximation method (MAM) is utilized to reduce the original nonlinear optimization problem to a sequence of approximations. Then, the Sequential Quadratic Programming (SQP) technique is applied to find the continuous solution. Following that, the implementation of discrete capability into the MAM is developed to solve the mixed discrete-continuous optimization problems. Findings: – The efficiency and rate of convergence of the developed hybrid algorithms outperforming GA are examined by six detailed case studies in the ten-bar planar truss problem and the superiority of the Hooke-Jeeves assisted MAM algorithm over the other two hybrid algorithms and GAs is concluded. Originality/value: – The authors propose three efficient hybrid algorithms: the rounding-off, the coordinate search, and the Hooke-Jeeves search assisted MAMs, to solve nonlinear mixed discrete-continuous optimization problems. Implementations include the development of new procedures for sampling discrete points, the modification of the trust region adaptation strategy, and strategies for solving mix optimization problems. To improve the efficiency and effectiveness of metamodel construction, regressors φ defined in this paper can have the form in common with the empirical formulation of the problems in many engineering subjects

Solid optical fiber with tunable bandgaps based on curable polymer infiltrated photonic crystal fiber

We demonstrated the realization and characterization of a solid photonic bandgap fiber (SPBF) with a compact size of about 10 mm and a high wavelength sensitivity of up to -4.034 nm/°C by means of fully infiltrating an ultraviolet curable polymer with a high refractive index of 1.515 into air holes of a photonic crystal fiber (PCF). To the best of our knowledge, it was the first time that the SPBF with tunable bandgaps was fabricated in the conventional index-guiding PCF. Compared with conventional fluid filled PBFs, the proposed SPBF can be stable to temperature and other environmental effects and maintain a large extinction ratio of more than 30 dB within a broad wavelength. The splicing between the SPBF and single mode fibers has been solved. Moreover, it is observed that the bandwidth of bandgap (G2) gradually broadens with the increase in temperature

Role of hepatitis B surface antigen in the development of hepatocellular carcinoma: regulation of lymphoid enhancer-binding factor 1

<p>Abstract</p> <p>Background</p> <p>There are around 350 million of hepatitis B surface antigen (HBsAg) carriers worldwide, and among them, high risk of developing hepatocellular carcinoma (HCC) has been identified by epidemiological studies. To date, the molecular role of HBsAg in HCC development has not been fully studied. We have previously reported that in cell cultures, HBsAg up-regulated the expression of lymphoid enhancer-binding factor 1 (LEF-1), a key component of the <it>Wnt </it>pathway. In this study we aimed to study this effect of HBsAg on LEF-1 in the development of HCC.</p> <p>Methods</p> <p>Expression of HBsAg, LEF-1 and its downstream effector genes were compared among 30 HCCs, their peritumor tissue counterparts and 9 normal control liver tissues by quantitative real-time PCR. In addition, immunohistochemical staining studies on HBsAg and LEF-1 expression were conducted among these samples.</p> <p>Results</p> <p>The expression of LEF-1 was compared between 13 HBsAg positive HCC tissues and 17 HBsAg negative HCC tissues. Simultaneous detection of LEF-1 and HBsAg was observed in HBsAg positive HCC tissues and, additionally, the simultaneous detection of HBsAg and LEF-1 was more pronounced in peritumor tissues, compared to that in the tumor tissues. The distribution of cellular LEF-1 in peritumor tissues was predominantly in the cytoplasm; while LEF-1 in the tumor tissues was located either exclusively in the nucleus or both in the nucleus and cytoplasm. By real-time PCR, the expression levels of LEF-1 downstream effector genes <it>cyclin D1 </it>and <it>c-myc </it>were higher in peritumor cells compared to that of the tumor cells. However, a 38 kDa truncated isoform of LEF-1, rather than the 55 kDa wild-type LEF-1, was significantly elevated in the HBsAg positive tumor cells.</p> <p>Conclusion</p> <p>Data indicate that deregulation of the <it>Wnt </it>pathway by HBsAg occurred in HBV-associated HCCs, but was more pronounced in the peritumor cells. It is speculated that HBsAg could stimulate proliferation and functional modification of hepatocytes via LEF-1 through the <it>Wnt </it>pathway at the pre-malignant stage.</p