Functionally graded structure of a nitride-strengthened Mg_(2)Si-based hybrid composite

The ex-situ incorporation of the secondary SiC reinforcement,along with the in-situ incorporation of the tertiary and quaternary Mg_(3)N_(2) and Si_(3)N_(4) phases,in the primary matrix of Mg_(2)Si is employed in order to provide ultimate wear resistance based on the laser-irradiation-induced inclusion of N_(2) gas during laser powder bed fusion.This is substantialized based on both the thermal diffusion-and chemical reactionbased metallurgy of the Mg_(2)Si–SiC/nitride hybrid composite.This study also proposes a functional platform for systematically modulating a functionally graded structure and modeling build-direction-dependent architectonics during additive manufacturing.This strategy enables the development of a compositional gradient from the center to the edge of each melt pool of the Mg_(2)Si–SiC/nitride hybrid composite.Consequently,the coefficient of friction of the hybrid composite exhibits a 309.3%decrease to–1.67 compared to–0.54 for the conventional nonreinforced Mg_(2)Si structure,while the tensile strength exhibits a 171.3%increase to 831.5 MPa compared to 485.3 MPa for the conventional structure.This outstanding mechanical behavior is due to the(1)the complementary and synergistic reinforcement effects of the SiC and nitride compounds,each of which possesses an intrinsically high hardness,and(2)the strong adhesion of these compounds to the Mg_(2)Si matrix despite their small sizes and low concentrations.

Defocused imaging-based quantification of plasmon-induced distortion of single emitter emission

Optical properties of single emitters can be significantly improved through the interaction with plasmonic structures,leading to enhanced sensing and imaging capabilities.In turn,single emitters can act as sensitive probes of the local electromagnetic field surrounding plasmonic structures,furnishing fundamental insights into their physics and guiding the design of novel plasmonic devices.However,the interaction of emitters in the proximity to a plasmonic nanostructure causes distortion,which hinders precise estimation of position and polarization state and is one of the reasons why detection and quantification of molecular processes yet remain fundamentally challenging in this era of super-resolution.Here,we investigate axially defocused images of a single fluorescent emitter near metallic nanostructure,which encode emitter positions and can be acquired in the far-field with high sensitivity,while analyzing the images with pattern matching algorithm to explore emitter-localized surface plasmon interaction and retrieve information regarding emitter positions.Significant distortion in defocused images of fluorescent beads and quantum dots near nanostructure was observed and analyzed by pattern matching and finite-difference time-domain methods,which revealed that the distortion arises from the emitter interaction with nanostructure.Pattern matching algorithm was also adopted to estimate the lateral positions of a dipole that models an emitter utilizing the distorted defocused images and achieved improvement by more than 3 times over conventional diffraction-limited localization methods.The improvement by defocused imaging is expected to provide a way of enhancing reliability when using plasmonic nanostructure and diversifying strategies for various imaging and sensing modalities.

Simultaneous emission of orthogonal handedness in circular polarization from a single luminophore

The direct emission of circularly polarized(CP)light improves the efficiency of an organic light-emitting diode and characterizes the secondary structure of proteins.In most cases,CP light is generated from a luminescent layer containing chiral characteristics,thereby generating only one kind of CP light in an entire device.Here,we propose direct CP light emissions using a twisted achiral conjugate polymer without any chiral dopant as an emitting layer(EML).The twisted structure is induced in the mesogenic conjugate polymer due to its elasticity by applying different alignment directions to its upper and lower interfaces.Furthermore,we demonstrate the simultaneous emission of orthogonal CP light in a single luminescent device by patterning different alignment directions on the surfaces of the EML.The light source with multipolarization including the orthogonal CP states is applicable to many applications in biosensors and optical devices.