A nonlocal curve flow in centro-affine geometry

In this paper, the isoperimetric inequality in centro-affine plane geometry is obtained. We also investigate the long-term behavior of an invariant plane curve flow, whose evolution process can be expressed as a second-order nonlinear parabolic equation with respect to centro-affine curvature. The forward and backward limits in time are discussed, which shows that a closed convex embedded curve may converge to an ellipse when evolving according to this flow

Effect of Shot Peening on Surface Characteristics of Ni-Based Single-Crystal Superalloy

The effect of shot peening on surface characteristics of DD3 Ni-based single-crystal superalloy including microstructures, texture and residual stress were investigated, utilizing XRD analysis. Results showed that the polycrystals was introduced into the surface of single-crystal specimen by shot peeing and the initial texture (200) was erased after 60 s-processing. The variation in microstructure was mainly influenced by the processing time and finer domains as well higher microstrain were obtained after 60 s-processing. The value of residual stress depended upon processing time and measurement direction. In the early period of processing (³10 s), residual stress was anisotropy, being significant smaller in h110i direction. With the processing time increased, the anisotropic residual stress gradually changed to isotropic residual stress, due to domainorientation randomization, domain refinement and increase in plastic strain. Also increasing processing time could significantly enhance the magnitude of residual stress and the microhardness. In addition, the influence of processing time on work hardening and residual stress was discussed, based on the deformation mechanism

Expression of CD39 on FoxP3+ T regulatory cells correlates with progression of HBV infection

BACKGROUND: Although it is known that regulatory T cells (Tregs) can suppress the function of effector T cells, and may contribute to impaired immune response, the precise role of Tregs during the course of hepatitis B virus (HBV) infection remains to be elucidated. A newly identified subset of the CD4(+)Foxp3(+ )Tregs, the CD39(+ )Tregs, has been associated with viral infections and autoimmune diseases. Therefore, we hypothesized that this discrete Treg subset may contribute to the chronic infection of HBV. RESULTS: Initial characterization studies of healthy peripheral CD39(+)FoxP3(+)CD4(+ )T cells revealed that the majority were CD45RA(- )Treg cells. Subsequent analysis of HBV-infected patients (38 asymptomatic HBV carriers (AsCs), 37 chronic active hepatitis B (CAH), 29 HBV-associated acute-on-chronic liver failure (ACLF)) and healthy individuals (25 controls) was conducted to assess association with HBV copy number and the liver injury marker alanine aminotransferase (ALT). A higher percentage of CD39(+ )Tregs was detected within the population of FoxP3(+)CD4(+ )T cells in peripheral blood of AsCs patients. Moreover, the percentage of CD39(+ )Tregs was significantly less in CAH and ACLF patients. The increased proportions of circulating CD39(+ )Tregs were positively correlated with serum viral load, but inversely correlated with serum ALT level. CONCLUSION: These findings not only suggest that CD39(+ )Treg cells may be involved in HBV disease progression but also identify CD39(+ )Tregs as a dynamic immune regulatory cell population that may represent a new target of immunomodulatory therapeutic interventions

Fabrication of micro-scale radiation shielding structures using tungsten nanoink through electrohydrodynamic inkjet printing

Electronics components used in space and strategic missions are exposed to harsh radiation environments, which could cause operational malfunction of the system through lattice displacement or ionization effects. One potential solution is to use tungsten as radiation shielding. Tungsten is a very effective material in shielding electronic components and manufacturing gratings for x-ray imaging. However, intrinsic properties of tungsten (e.g. density, chemical/thermal inertness and hardness) post a significant challenge of fabricating the material into micro-scale and delicate structures, especially in electronic device fabrication. To address the problem, we designed a new tungsten nanoink and developed a straightforward approach to create tungsten micro-structures by 3D printing. Various microstructures down to 10 µm resolution have been patterned and fabricated by electrohydrodynamic inkjet (e-jet) printing using tungsten nanoink. By optimizing process parameters (voltage modality) and materials properties (ink formulation), the dimension and morphology of the structures can be precisely controlled. An AC-modulated voltage was employed during the e-jet printing process to make the patterns much more controllable and stable. Multi-layer tungsten lines were characterized by x-ray imaging and exhibited excellent absorption of x-ray radiation. With the same thickness, printed lines showed nearly 1/3 absorptivity of x-ray radiation of bulk tungsten, leading to significant radiation attenuation effectiveness. Tungsten nanoink is a new material used in e-jet printing that has not been reported in the literature to the best of authors\u27 knowledge. The study establishes a new methodology of manufacturing micro-nano scale shielding components for electronic devices and rapid prototyping of gratings and collimators in radiography for medical and inspection applications. The research also provides practical guidance to fabricate high melting-point metals via nanoink and micro/nano scale 3D printing

Activation and Assembly of Plasmonic-Magnetic Nanosurfactants for Encapsulation and Triggered Release

Multifunctional surfactants hold great potentials in catalysis, separation, and biomedicine. Highly active plasmonic-magnetic nanosurfactants are developed through a novel acid activation treatment of Au–Fe3O4 dumbbell nanocrystals. The activation step significantly boosts nanosurfactant surface energy and enables the strong adsorption at interfaces, which reduces the interfacial energy one order of magnitude. Mediated through the adsorption at the emulsion interfaces, the nanosurfactants are further constructed into free-standing hierarchical structures, including capsules, inverse capsules, and two-dimensional sheets. The nanosurfactant orientation and assembly structures follow the same packing parameter principles of surfactant molecules. Furthermore, nanosurfactants demonstrate the capability to disperse and encapsulate homogeneous nanoparticles and small molecules without adding any molecular surfactants. The assembled structures are responsive to external magnetic field, and triggered release is achieved using an infrared laser by taking advantage of the enhanced surface plasmon resonance of nanosurfactant assemblies. Solvent and pH changes are also utilized to achieve the cargo release

Microwave photonic signal generation in an optically injected discrete mode semiconductor laser

This article belongs to the Special Issue Microwave Photonics Applications.In this paper, microwave photonic signal generation based on the period-one dynamic of optically injected discrete mode (DM) semiconductor lasers has been experimentally demonstrated and numerically simulated. The results show that the frequency of the generated microwave increases linearly with the frequency detuning or optical injection ratio. In addition, a single optical feedback loop is sufficient to reduce the microwave linewidth without significantly deteriorating side mode suppression. The simulation results using a model considering the nonlinear dependencies of the carrier recombination agree well with the experimental results, which indicates that the nonlinear carrier recombination effect is important in determining the nonlinear dynamics of optically injected DM lasers.This research was funded in part by the DESTINI project (2017/COL/007) funded by the ERDF under the SMART Expertise scheme; in part by the DSP Centre (82085) funded by the ERDF through the Welsh Government; and in part by Ministerio de Ciencia e Innovación, Spain, under grant RTI2018-094118-B-C22 MCIN/AEI/FEDER, UE.Peer reviewe