A multiscale non-orthogonal model for tensile properties of uncoated and coated F-12 aramid fabric

Coated F-12 aramid fabric can be used as the balloon envelopes material because of the high strength and light weight performance. In this paper, a multiscale non-orthogonal material model was established to capture the tensile properties of F-12 fabric with and without polyethylene terephthalate-aluminum (PET-Al) coating. Off-axial monotonic tensile tests were carried out to validate the material model. The nonlinearity and anisotropic properties of the coated and uncoated fabrics were investigated. In this model, the stress was obtained based on the equilibrium equations and yarn constitutive model in mesoscale. The mesoscale configuration was observed through optical microscope and SEM. The material orientation was aligned with the yarn directions and the stress was updated in real time. The material model was implemented by user material subroutine in ABAQUS and simulate fabric off-axial tensile test. In addition, a theory model to calculate the elastic property of the fabric was also set up using the mesoscale deformation mechanism. The simulation results were compared with the test and theory results. Results suggest that simulation results were agree well with test results. The fabrics were nearly linearity in weft direction, while the stressstrain curve exhibited obvious nonlinearity in warp direction. The tensile modulus of the fabric showed orthotropic behaviour rather than the strength. The coating can affect the strength and failure model of F-12 fabric. Yarn slip was the mostly failure model in uncoated fabric while break in coated fabric. Research in this study provides certain reference in analysis and design for balloon envelops

NSNO: Neumann Series Neural Operator for Solving Helmholtz Equations in Inhomogeneous Medium

In this paper, we propose Neumann Series Neural Operator (NSNO) to learn the solution operator of Helmholtz equation from inhomogeneity coefficients and source terms to solutions. Helmholtz equation is a crucial partial differential equation (PDE) with applications in various scientific and engineering fields. However, efficient solver of Helmholtz equation is still a big challenge especially in the case of high wavenumber. Recently, deep learning has shown great potential in solving PDEs especially in learning solution operators. Inspired by Neumann series in Helmholtz equation, we design a novel network architecture in which U-Net is embedded inside to capture the multiscale feature. Extensive experiments show that the proposed NSNO significantly outperforms the state-of-the-art FNO with at least 60\% lower relative $L^2$-error, especially in the large wavenumber case, and has 50\% lower computational cost and less data requirement. Moreover, NSNO can be used as the surrogate model in inverse scattering problems. Numerical tests show that NSNO is able to give comparable results with traditional finite difference forward solver while the computational cost is reduced tremendously

Stat3 regulates microtubules by antagonizing the depolymerization activity of stathmin

Stat3 is a member of the signal transducer and activator of transcription family, which is important in cytokine signaling. Gene ablation studies have revealed a requirement for Stat3 in diverse biological processes (Akira, S. 2000. Oncogene. 19: 2607–2611; Levy, D.E., and C.K. Lee. 2002. J. Clin. Invest. 109:1143–1148). Previously, the function of Stat3 had been attributed exclusively to its transcriptional activity in the nucleus. In this study, we reveal an interaction between Stat3 and the microtubule (MT)-destabilizing protein stathmin. Stathmin did not overtly affect ligand-stimulated Stat3 activation. In contrast, the expression of Stat3 is required for the stabilization of MTs and cell migration. We further demonstrate that Stat3-containing cells are resistant to the MT-destabilizing effect of stathmin overexpression. In addition, down-regulation of stathmin protein levels in Stat3-deficient cells partially reversed the MT and migration deficiencies. Recombinant Stat3 was also capable of reversing stathmin inhibition of tubulin polymerization in vitro. Our results indicate that Stat3 modulates the MT network by binding to the COOH-terminal tubulin-interacting domain of stathmin and antagonizing its MT destabilization activity

Two-dimensional cylindrical thermal cloak designed by implicit transformation method

As a new-type technology of heat management, thermal metamaterials have attracted more and more attentions recently and thermal cloak is a typical case. Thermal conductivity of thermal cloak designed by coordinate transformation method is usually featured by inhomogeneity, anisotropy and local singularity. Explicit transformation method, which is commonly used to design thermal cloak with the coordinate transformation known in advance, has insufficient flexibility, making it hard to proactively reduce the difficulty of device fabrication. In this work, we designed the thermal conductivity of two-dimensional (2D) cylindrical thermal cloak using the implicit transformation method without knowledge of the coordinate transformation in advance. With two classes of generation functions taken into consideration, this study adopted full-wave simulations to analyze the thermal cloaking performances of designed thermal cloaks. Material distributions and simulation results showed that the implicit transformation method has high flexibility. The form of coordinate transformation not only influences the homogeneity and anisotropy but also directly influences the thermal cloaking performance. An improved layered structure for 2D cylindrical thermal cloak was put forward based on the generation function g(r) = r15, which reduces the number of the kinds of constituent materials while guaranteeing good thermal cloaking performance. This work provides a beneficial guidance for reducing the fabrication difficulty of thermal cloak

A multiscale non-orthogonal model for tensile properties of uncoated and coated F-12 aramid fabric

Coated F-12 aramid fabric can be used as the balloon envelopes material because of the high strength and light weight performance. In this paper, a multiscale non-orthogonal material model was established to capture the tensile properties of F-12 fabric with and without polyethylene terephthalate-aluminum (PET-Al) coating. Off-axial monotonic tensile tests were carried out to validate the material model. The nonlinearity and anisotropic properties of the coated and uncoated fabrics were investigated. In this model, the stress was obtained based on the equilibrium equations and yarn constitutive model in mesoscale. The mesoscale configuration was observed through optical microscope and SEM. The material orientation was aligned with the yarn directions and the stress was updated in real time. The material model was implemented by user material subroutine in ABAQUS and simulate fabric off-axial tensile test. In addition, a theory model to calculate the elastic property of the fabric was also set up using the mesoscale deformation mechanism. The simulation results were compared with the test and theory results. Results suggest that simulation results were agree well with test results. The fabrics were nearly linearity in weft direction, while the stressstrain curve exhibited obvious nonlinearity in warp direction. The tensile modulus of the fabric showed orthotropic behaviour rather than the strength. The coating can affect the strength and failure model of F-12 fabric. Yarn slip was the mostly failure model in uncoated fabric while break in coated fabric. Research in this study provides certain reference in analysis and design for balloon envelops

A Fluid Management System For A Multiple Nozzle Array Spray Cooler

An experimental investigation of a fluid management system for a multiple nozzle spray cooler array was conducted. A fluid management or suction system was used to control the liquid film layer thickness needed for maximum heat transfer. An array of sixteen pressure atomized spray nozzle along with an imbedded fluid suction were constructed. Two surfaces were spray tested one being a clear grooved Plexiglas plate used for visualization and the other being a bottom heated grooved 4.5 × 4.5 cm2 copper plate used to determine the heat flux. The suction system utilized an array of thin copper tubes of outer diameter 3.175 mm to extract excess liquid from the cooled surface. Pure water was ejected from two spray nozzle configurations at flow rates of 0.7 L/min to 1 L/min per nozzle. It was found that the fluid management system provided fluid removal maximum efficiencies of 98% with a 4-nozzle array, and 90% with the full 16-nozzle array for the downward spraying orientation. The corresponding heat fluxes for the multiple spray head configuration were found with and without the aid of the fluid management system. It was found that the fluid management system increased heat fluxes on the average of 30 W/cm2 at similar values of superheat. © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Design Of A Two-Phase Separator For Variable Gravity Applications

Vapor-liquid two-phase flow systems are gaining importance in space -based and aerospace applications due to their compactness, reliability and high power-to-weight ratio. A phase separator is needed, if a mechanical pump or compressor is required. This paper describes an experimental study for the design and development of a two-phase separator. The main aim of this study is to design a separator that could separate some amount of liquid-free vapor from the two-phase mixture. The design consists of a coiled tube with a number of holes drilled on the outside. Two-phase mixture is sent into the tube one end and the separation is achieved by using centrifugal force that is developed due to the motion of the fluid inside a coil tube. The dense fluid is pushed towards the outer radius of the tube and is extracted from the holes. Different parameters like length of the tube, diameter of the tube, diameter of the coil, diameter of the holes, distance between the holes, flow rate of the two-phase fluid mixture in the tube and material of the tube have been considered. The apparatus was built and tested for various input flow rates with the input vapor to liquid volumetric ratio ranging from 50:1 to 100:1. For the experiment, air and water are used as gas and liquid respectively. The apparatus was tested positioned in three different ways - horizontal, vertical with fluid mixture flow from top to bottom and vice versa. A preliminary separation efficiency of 93% was observed in the position when the fluid mixture is sent from the top of the tubular coil and 100% in the other two positions. It was found that the flow patterns inside the tube determine the range in which the apparatus functions independent of gravity. The apparatus would be tested in the NASA KC-135 aircraft in the future. © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Effects of LED light on Acacia melanoxylon bud proliferation in vitro and root growth ex vitro

This study examines the effects of light emitting diodes (LEDs) on tissue culture proliferation of Acacia melanoxylon plantlets among five different clones (FM1, FM2, FM4, FM5, and FM10). Shoot bud apex cuttings were transplanted onto Murashige and Skoog basal medium containing 0.1 mg L-1 6-benzyladenine and 0.5 mg L-1 naphthalene acetic acid and cultured in vitro for 40 days. Root growth was studied under different light intensities and photoperiods ex vitro. The bud proliferation coefficient was greatest under a light intensity of 45 μmol m-2 s-1 photosynthetic photon flux and photoperiod of 16 h light, but decreased as the light intensity increased. However, the greatest light intensity was beneficial for the growth of robust plantlets. Plantlets exposed to red and blue LED combinations grew tall and green, with a small number of roots. Plantlets also grew taller and some roots expanded under the longer photoperiod. Increased light intensity had positive effects on root number and rooting rate, and prolonged light greatly increased root number. Therefore, lower light intensity and a short photoperiod were beneficial for bud proliferation, while red/blue LED combinations, increased light intensity, and longer light illumination were beneficial for plantlet growth and root growth of Acacia melanoxylon

Inhibitory Effect and Mechanism of Trichoderma taxi and Its Metabolite on Trichophyton mentagrophyte

Trichophyton mentagrophytes is an important zoonotic dermatophyte, which seriously harms the skin of humans and animals. Chemical drugs are generally used for the prevention and treatment of the disease caused by T. mentagrophytes. Discovering new compounds from natural products is an important approach for new drug development. Trichoderma includes a variety of fungal species used for biological control of phytopathogenic fungi. However, the antifungal effects of Trichoderma and their metabolites on zoonotic fungal pathogens are largely unknown. Here, the effect of trichodermin, a metabolite derived from the plant endophytic fungus Trichoderma taxi, on T. mentagrophytes was examined, and the underlying mechanism was explored. T. mentagrophytes growth was suppressed significantly by trichodermin and completely inhibited under 1000 μg/mL trichodermin. The production and germination of T. mentagrophytes spores were remarkably reduced upon exposure to trichodermin, in comparison with control samples. Treatment of lesions caused by T. mentagrophytes on the rabbit skin with 1 mg/mL trichodermin prompted the healing process significantly; however, 20 mg/mL trichodermin was likely toxic to the skin. Under trichodermin treatment, the number of mitochondria in T. mentagrophytes increased significantly, while a few mitochondria-related genes decreased, indicating possible mitochondrial damage. In transcriptome analysis, the GO terms enriched by DEGs in the trichodermin-treated group included carbohydrate metabolic process, integral component of membrane, intrinsic component of membrane, and carbohydrate binding, while the enriched KEGG pathways comprised biosynthesis of secondary metabolites, glycolysis/gluconeogenesis, and carbon metabolism. By comparing the wild type and a gene deletion strain of T. mentagrophytes, we found that CDR1, an ABC transporter encoding gene, was involved in T. mentagrophytes sensitivity to trichodermin