Recent progress on structural coloration

Structural coloration generates colors by the interaction between incident light and micro-or nanoscale structures.It has received tremendous interest for decades,due to advantages including robustness against bleaching and environmentally friendly properties(compared with conventional pigments and dyes).As a versatile coloration strategy,the tuning of structural colors based on micro-and nanoscale photonic structures has been extensively explored and can enable a broad range of applications including displays,anti-counterfeiting,and coating.However,scholarly research on structural colors has had limited impact on commercial products because of their disadvantages in cost,scalability,and fabrication.In this review,we analyze the key challenges and opportunities in the development of structural colors.We first summarize the fundamental mechanisms and design strategies for structural colors while reviewing the recent progress in realizing dynamic structural coloration.The promising potential applications including optical information processing and displays are also discussed while elucidating the most prominent challenges that prevent them from translating into technologies on the market.Finally,we address the new opportunities that are underexplored by the structural coloration community but can be achieved through multidisciplinary research within the emerging research areas.

Mechanism and kinetics study on the ozonolysis reaction of 2,3,7,8-TCDD in the atmosphere

The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin （2,3,7,8-TCDD） is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O are introduced in detail at the method of MPWB1K/6-31＋G（d,p）//MPWB1K/6- 311＋G（3df,2p） level. In ozonolysis, H2O is an important source of OH radical formation and initiated the subsequent degradation reaction. The Rice-Ramsperger-Kassel-Marcus （RRKM） theory was applied to calculate rate constants with the temperature ranging from 200 to 600 K. The rate constant of reaction between 2,3,7,8-TCDD and 03 is 4.80 × 10^-20 cm3/（mole.sec） at 298 K and 760 Tort. The atmospheric lifetime of the reaction species was estimated according to rate constants, which is helpful for the atmospheric model study on the degradation and risk assessment of dioxin.

To image,or not to image:class-specific diffractive cameras with all-optical erasure of undesired objects

Privacy protection is a growing concern in the digital era,with machine vision techniques widely used throughout public and private settings.Existing methods address this growing problem by,e.g.,encrypting camera images or obscuring/blurring the imaged information through digital algorithms.Here,we demonstrate a camera design that performs class-specific imaging of target objects with instantaneous all-optical erasure of other classes of objects.This diffractive camera consists of transmissive surfaces structured using deep learning to perform selective imaging of target classes of objects positioned at its input field-of-view.After their fabrication,the thin diffractive layers collectively perform optical mode filtering to accurately form images of the objects that belong to a target data class or group of classes,while instantaneously erasing objects of the other data classes at the output field-of-view.Using the same framework,we also demonstrate the design of class-specific permutation and class-specific linear transformation cameras,where the objects of a target data class are pixel-wise permuted or linearly transformed following an arbitrarily selected transformation matrix for all-optical class-specific encryption,while the other classes of objects are irreversibly erased from the output image.The success of class-specific diffractive cameras was experimentally demonstrated using terahertz(THz)waves and 3D-printed diffractive layers that selectively imaged only one class of the MNIST handwritten digit dataset,all-optically erasing the other handwritten digits.This diffractive camera design can be scaled to different parts of the electromagnetic spectrum,including,e.g.,the visible and infrared wavelengths,to provide transformative opportunities for privacy-preserving digital cameras and task-specific data-efficient imaging.

Effect of oxide nanoparticles on the morphology and fluidity of phospholipid membranes and the role of hydrogen bonds

Engineered oxide nanoparticles（NPs） are widely applied in insulators,catalyzers,paints,cosmetic products,textiles and semiconductors.Their attachment on cell membrane may lead to cytotoxicity.The effects of Al_2O_3,Fe_2O_3,SiO_2,TiO_2and ZnO NPs on membrane integrity and fluidity were studied using giant or small unilamellar vesicles in this study.Al_2O_3 and SiO_2NPs disrupted the oppositely charged membrane,indicating the important role of electrostatic attraction.However,Fe_2O_3,TiO_2and ZnO NPs did not cause serious membrane disruption as Al_2O_3 and SiO_2 NPs.Membrane fluidity was evaluated by the generalized polarity（GP） values of Laurdan fluorescent emission.SiO_2 NPs induce the membrane gelation of both positively and negatively charged membrane.Al_2O_3 and ZnO NPs induced the gelation of the oppositely charged membrane,but did not cause obvious membrane gelation to the like charged membrane.The phospholipid molecular structural changes after NP exposure were analyzed by Fourier transform infrared（FT-IR） spectroscopy.FT-IR spectra revealed the hydrogen bond formation between NPs and the carbonyl/phosphate groups of phospholipids.Al_2O_3 and SiO_2 NPs showed strongest evidence of hydrogen bonding on their FT-IR spectra.It was consistent with the microscopic observation and fluorescent data that Al_2O_3 and SiO_2 NPs caused more serious membrane disruption and gelation.This study on membrane damage provides further knowledge on the cytotoxicity of nanomaterials and the safety of NP application.

Theoretical study on the degradation reaction of octachlorinated dibenzo-p-dioxin with atomic oxygen o(3P) in dielectric barrier discharge reactor

Dielectric barrier discharges （DBD） have been used in the degradation of dioxins due to the large number of excimers and free radicals produced in discharge process. In this article, the density functional theory （DFT） is used to study the degradation mechanism of octachlorinated dibenzo-p-dioxin （OCDD） with the atomic oxygen O（3P） in DBD reactor. The reactants, intermediates, transition states and products are optimized at the MPWB1K/6- 31 ＋ G（d,p） level. The vibrational frequencies have been calculated at the same level. The reaction pathways and mechanisms are analyzed in detail. The effect of removing the chlorine atom on environment also has been discussed.