Emergent Recurrent Extension Phase Transition in a Quasiperiodic Chain

We study $p$-wave superconducting quasiperiodic chains with staggered potential. The result shows a counter-intuitive phase transition phenomenon, i.e., recurrent extension phase transition (REPT). By analyzing the participation ration and scaling behavior, we prove the existence of REPT phenomenon, which, in concrete terms, means that the system will repeatedly return from the intermediate phase to the extended phase as the quasiperiodic or staggered strength grows. Furthermore, our finding is also quite different from the traditional understanding of intermediate phase (composed only of the pure extended phase and pure localized phase) in that, the new intermediate phase described here, stemming from the competition between staggered potential and $p$-wave pairing, actually falls into three types by bringing in the critical phase. To be specific, the new intermediate phases are composed of the critical + extended states, the critical + localized states, and the critical + extended + localized states, respectively.Comment: 12 pages, 8 figure

Lipopolysaccharides (LPS) Induced Angiogenesis During Chicken Embryogenesis is Abolished by Combined ETA/ETB Receptor Blockade

Background/Aims: Angiogenesis plays a key role during embryonic development. The vascular endothelin (ET) system is involved in the regulation of angiogenesis. Lipopolysaccharides (LPS) could induce angiogenesis. The effects of ET blockers on baseline and LPS-stimulated angiogenesis during embryonic development remain unknown so far. Methods: The blood vessel density (BVD) of chorioallantoic membranes (CAMs), which were treated with saline (control), LPS, and/or BQ123 and the ETB blocker BQ788, were quantified and analyzed using an IPP 6.0 image analysis program. Moreover, the expressions of ET-1, ET-2, ET3, ET receptor A (ETRA), ET receptor B (ETRB) and VEGFR2 mRNA during embryogenesis were analyzed by semi-quantitative RT-PCR. Results: All components of the ET system are detectable during chicken embryogenesis. LPS increased angiogenesis substantially. This process was completely blocked by the treatment of a combination of the ETA receptor blockers-BQ123 and the ETB receptor blocker BQ788. This effect was accompanied by a decrease in ETRA, ETRB, and VEGFR2 gene expression. However, the baseline angiogenesis was not affected by combined ETA/ETB receptor blockade. Conclusion: During chicken embryogenesis, the LPS-stimulated angiogenesis, but not baseline angiogenesis, is sensitive to combined ETA/ETB receptor blockade. (C) 2018 The Author(s) Published by S. Karger AG, Base

Investigation of riblet geometry and start locations of herringbone riblets on pressure losses in a linear cascade at low Reynolds numbers

In this paper, the effects of an array of herringbone riblets with different riblet geometry (height and spacing) and start locations on the pressure losses in a cascade of diffuser blades are investigated over a range of low Reynolds numbers (0.50 × 105–1.00 × 105). The herringbone riblets with a given geometry are found to produce a profound modification to the wake structure above certain critical Reynolds numbers. It is also found that within the range of parameters tested an increase in riblet height and riblet spacing results in an onset of significant control effect at a lower Reynolds number, which is accompanied by a slight reduction in zone-averaged loss coefficient and flow turning angle. An upstream shift of the start position of the riblet array along the blades enables the riblets to become effective at a lower Reynolds number at the expense of a reduced loss reduction and flow turning angle. A semi-empirical relationship between the ratio of riblet height to local baseline boundary layer displacement thickness and the critical Reynolds number is established using the present experimental data. A preliminary methodology for designing the herringbone riblets to ensure an effective control of 2D flow separations around the mid-span of diffuser blades over a specified range of Reynolds numbers is also proposed

Characteristics and mechanisms of particle adhesion patterns in an aerodynamic cyclone

Characteristics of particle adhesion (deposition) patterns in an aerodynamic cyclone were studied by both experimental methods and computational fluid dynamic (CFD) simulation methods. The cyclone used in the experiment was made of acrylonitrile butadiene styrene (ABS). The particles were a plaster material, with an average size of 1.13 μm and a density of 2300 kg/m3. Four levels of particle load rates were examined, ranging from 0.28 g/m3 to 0.96 g/m3 at a fixed mass flow rate of 2.1 g/s. Experimental results showed three key features of particle adhesion patterns. They are large-scale spiral patterns (SPs), small-scale wave patterns (WPs), and thick adhesion layer (TAL) at the cyclone tip region. It was observed that the SPs had five turns and the WPs were periodic discrete patterns that crept slowly against the flow direction. The formation of WPs was explained based on the Barchan sand dune mechanism. Under zero particle load rate, six different mass flow rates ranging from 1.24 g/s to 3.16 g/s were simulated using CFD. It was found that the precessional bent vortex end (PBVE), precessing along the circumference of the cyclone tip, occurred close to the cyclone tip. The PBVE was believed to be the cause of the TAL, because there was a weak wall shear stress region below the PBVE. In addition, particle trajectories were simulated at a mass flow rate of 2.26 g/s. Simulation results showed that particles had spiral trajectories that were supposed to be linked with the SPs

Investigation of strain-sensitive properties of porous media through micro-CT imaging and numerical modelling

Strain-sensitive characteristics of porous media are studied through micro-CT imaging and numerical simulations. First, high-fidelity Discrete Element Method (DEM) models are constructed for practical porous media based on micro-CT images. These DEM models prioritize the overall system morphology over individual grain/particle shapes, ensuring robustness and flexibility controlled by easily adjustable algorithm parameters. Subsequently, we validate the accuracy of our proposed DEM models by comparing them with the Finite Element Method (FEM), achieving consistent agreement across all test cases. Finally, the CT-image based DEM approach is employed to investigate strain-sensitive properties of porous media, such as permeability, porosity, tortuosity, specific surface area, and fractal dimension. With a primary focus on transport and morphology properties, our approach is versatile and applicable to exploring various other properties of porous media. This study introduces a generic methodology for examining practical porous media under in-situ conditions, providing valuable insights into their response to stress and deformation

Discovery of four gravitational lensing systems by clusters in the SDSS DR6

We report the discovery of 4 strong gravitational lensing systems by visual inspections of the Sloan Digital Sky Survey images of galaxy clusters in Data Release 6 (SDSS DR6). Two of the four systems show Einstein rings while the others show tangential giant arcs. These arcs or rings have large angular separations (>8") from the bright central galaxies and show bluer color compared with the red cluster galaxies. In addition, we found 5 probable and 4 possible lenses by galaxy clusters.Comment: 6 pages, 3 figures. Added referenc