SINGLE CRYSTAL HARDENING——MECHANISMS AND DESCRIPTION

Various work hardening mechanisms, on the basis of their characteristics, are classified into two categories: the pile-up hardening and the tangle hardening. Together with a discussion about the experimental investigations of work hardening, the descriptions for those two basic hardening mechanisms are suggested, respectively. Combining these descriptions, a new single crystal hardening law is proposed, which can be used to describe work hardening, particularly the cyclic hardening of a crystal grain in a polycrystalline material. Furthermore, some relevant discussion on the new single crystal hardening law is also made in this paper.

Azimuthal rotation-controlled nanoinscribing for continuous patterning of period-and shapetunable asymmetric nanogratings

We present an azimuthal-rotation-controlled dynamic nanoinscribing(ARC-DNI)process for continuous and scalable fabrication of asymmetric nanograting structures with tunable periods and shape profiles.A sliced edge of a nanograting mold,which typically has a rectangular grating profile,slides over a polymeric substrate to induce its burrfree plastic deformation into a linear nanopattern.During this continuous nanoinscribing process,the“azimuthal angle,”that is,the angle between the moving direction of the polymeric substrate and the mold’s grating line orientation,can be controlled to tailor the period,geometrical shape,and profile of the inscribed nanopatterns.By modulating the azimuthal angle,along with other important ARC-DNI parameters such as temperature,force,and inscribing speed,we demonstrate that the mold-opening profile and temperature-and time-dependent viscoelastic polymer reflow can be controlled to fabricate asymmetric,blazed,and slanted nanogratings that have diverse geometrical profiles such as trapezoidal,triangular,and parallelogrammatic.Finally,period-and profile-tunable ARC-DNI can be utilized for the practical fabrication of diverse optical devices,as is exemplified by asymmetric diffractive optical elements in this study.

Mid-infrared chemical imaging of intracellular tau fibrils using fluorescence-guided computational photothermal microscopy

Amyloid proteins are associated with a broad spectrum of neurodegenerative diseases.However,it remains a grand challenge to extract molecular structure information from intracellular amyloid proteins in their native cellular environment.To address this challenge,we developed a computational chemical microscope integrating 3D midinfrared photothermal imaging with fluorescence imaging,termed Fluorescence-guided Bond-Selective Intensity Diffraction Tomography(FBS-IDT).Based on a low-cost and simple optical design,FBS-IDT enables chemical-specific volumetric imaging and 3D site-specific mid-IR fingerprint spectroscopic analysis of tau fbrils,an important type of amyloid protein aggregates,in their intracellular environment.Label-free volumetric chemical imaging of human cells with/without seeded tau fibrils is demonstrated to show the potential correlation between lipid accumulation and tau aggregate formation.Depth-resolved mid-infrared fingerprint spectroscopy is performed to reveal the protein secondary structure of the intracellular tau fibrils.3D visualization of theβ-sheet for tau fibril structure is achieved.

Challenging Nanopores with Analyte Scope and Environment

Nanopores are nanofluidic channels formed through thin membranes that can deliver standout single-molecule and single-particle sensing capabilities.Analytical targets include small molecules and nanoparticles,and the DNA,protein,and glycan biopolymers underpinning genomics,proteomics,and glycomics.Detection-notably even in the simplest implementation,resistive-pulse sensing-does not inherently require sample labeling and,thus,offers the potential for general sensing util-ity combined with the prospective benefits of reduced sample processing requirements.A key pursuit for biopolymer sens-ing is the characterization of monomer sequence.This review article will provide an overview of the use of nanopores for general chemical sensing and-omics-related applications,writ-large.The broad analyte scope provides fertile ground for a discussion of principles governing nanopore sensing and considerations useful for guiding nanopore development.For nanopores to be effective in the face of broad analyte scope,stringent requirements on analytical performance must be met within the particular analyte class without sacrificing the operational flexibility necessary to be responsive across classes presenting very different physical and chemical challenges.These sample-driven challenges provide a unifying framework for discussing aspects of nanopore fabrication,properties,and integration;sensing paradigms,performance,and prospects;fundamental electrokinetic and interfacial phenomena;and practical challenges facing the use and further development of nanopore devices.