Polarization-Encoded Lenticular Nano-Printing with Single-Layer Metasurfaces

Metasurface-based nano-printing has enabled ultrahigh-resolution grayscale or color image display. However, the maximum number of independent nano-printing images allowed by one single-layer metasurface is still limited despite many multiplexing methods that have been proposed to increase the design degree of freedom. In this work, we substantially push the multiplexing limit of nano-printing by transforming images at different observation angles into mapping the corresponding images to different positions in the Fourier space, and simultaneously controlling the complex electric field across multiple polarization channels. Our proposed Polarization-Encoded Lenticular Nano-Printing (Pollen), aided by a modified evolutionary algorithm, allows the display of several images based on the viewing angle, similar to traditional lenticular printing but without requiring a lenticular layer. In addition, it extends the display capability to encompass multiple polarization states. Empowered by the ability to control the complex amplitude of three polarization channels, we numerically and experimentally demonstrate the generation of 13 distinguished gray-scale Chinese ink wash painting images, 49 binary patterns, and three sets of 3D nano-printing images, totaling 25 unique visuals. These results present the largest number of recorded images with ultra-high resolution to date. Our innovative Pollen technique is expected to benefit the development of modern optical applications, including but not limited to optical encryption, optical data storage, lightweight display, and augmented reality and virtual reality

Concise Synthesis of (−)-Cycloclavine and (−)-5-<i>epi</i>-Cycloclavine via Asymmetric C–C Activation

To illustrate the synthetic significance of C–C activation methods, here we describe an efficient strategy for the enantioselective total syntheses of (−)-cycloclavine and (−)-5-<i>epi</i>-cycloclavine, which is enabled by an asymmetric Rh-catalyzed “cut-and-sew” transformation between benzocyclo­butenones and olefins. Despite the compact structure of cycloclavine with five-fused rings, the total synthesis was accomplished in 10 steps with a 30% overall yield. Key features of the synthesis include (1) a Pd-catalyzed tandem C–N bond coupling/allylic alkylation sequence to construct the nitrogen-tethered benzocyclobutenone, (2) a highly enantioselective Rh-catalyzed carboacylation of alkenes to forge the indoline-fused tricyclic structure, and (3) a diastereoselective cyclopropanation for preparing the tetrasubstituted cyclopropane ring. Notably, an improved catalytic condition has been developed for the nitrogen-tethered cut-and-sew transformation, which uses a low catalyst loading and allows for a broad substrate scope with high enantioselectivity (94–99% e.e.). The C–C activation-based strategy employed here is anticipated to have further implications for syntheses of other natural products that contain complex fused or bridged rings

Concise Synthesis of (−)-Cycloclavine and (−)-5-<i>epi</i>-Cycloclavine via Asymmetric C–C Activation

To illustrate the synthetic significance of C–C activation methods, here we describe an efficient strategy for the enantioselective total syntheses of (−)-cycloclavine and (−)-5-<i>epi</i>-cycloclavine, which is enabled by an asymmetric Rh-catalyzed “cut-and-sew” transformation between benzocyclo­butenones and olefins. Despite the compact structure of cycloclavine with five-fused rings, the total synthesis was accomplished in 10 steps with a 30% overall yield. Key features of the synthesis include (1) a Pd-catalyzed tandem C–N bond coupling/allylic alkylation sequence to construct the nitrogen-tethered benzocyclobutenone, (2) a highly enantioselective Rh-catalyzed carboacylation of alkenes to forge the indoline-fused tricyclic structure, and (3) a diastereoselective cyclopropanation for preparing the tetrasubstituted cyclopropane ring. Notably, an improved catalytic condition has been developed for the nitrogen-tethered cut-and-sew transformation, which uses a low catalyst loading and allows for a broad substrate scope with high enantioselectivity (94–99% e.e.). The C–C activation-based strategy employed here is anticipated to have further implications for syntheses of other natural products that contain complex fused or bridged rings

Effects of Combined UV and Chlorine Treatment on the Formation of Trichloronitromethane from Amine Precursors

The objective of this study was to investigate the effects of combined low-pressure ultraviolet (LPUV) irradiation and free chlorination on the formation of trichloronitromethane (TCNM) byproduct from amine precursors, including a commonly used polyamine coagulant aid (poly­(epichlorohydrin dimethylamine)) and simple alkylamines dimethylamine (DMA) and methylamine (MA). Results showed that TCNM formation can increase up to 15 fold by combined UV/chlorine under disinfection to advanced oxidation conditions. The enhancement effect is influenced by UV irradiance, chlorine dose, and water pH. Extended reaction time leads to the decay of TCNM by direct photolysis. The combined UV/chlorine conditions significantly promoted degradation of polyamine to generate intermediates, including DMA and MA, which are better TCNM precursors than polyamine, and also facilitated transformation of these amine precursors to TCNM. Under combined UV/chlorine, polyamine degradation was likely promoted by radical oxidation, photodecay of chlorinated polyamine, and chlorine oxidation/substitution. Promoted TCNM formation from primary amine MA was primarily due to radicals’ involvement. Promoted TCNM formation from secondary amine DMA likely involved a combination of radical oxidation, photoenhanced chlorination reactions, and other unknown mechanisms. Insights obtained in this study are useful for reducing TCNM formation during water treatment when both UV and chlorine will be encountered

Enantioselective Rh-Catalyzed Carboacylation of CN Bonds via C–C Activation of Benzocyclobutenones

Herein we describe the first enantioselective Rh-catalyzed carboacylation of oximes (imines) via C–C activation. In this transformation, the benzocyclobutenone C1–C2 bond is selectively activated by a low valent rhodium catalyst and subsequently the resulting two Rh–C bonds add across a CN bond, which provides a unique approach to access chiral lactams. A range of polycyclic nitrogen-containing scaffolds were obtained in good yields with excellent enantioselectivity. Further derivatization of the lactam products led to a rapid entry to various novel fused heterocycles

Enantioselective Rh-Catalyzed Carboacylation of CN Bonds via C–C Activation of Benzocyclobutenones

Herein we describe the first enantioselective Rh-catalyzed carboacylation of oximes (imines) via C–C activation. In this transformation, the benzocyclobutenone C1–C2 bond is selectively activated by a low valent rhodium catalyst and subsequently the resulting two Rh–C bonds add across a CN bond, which provides a unique approach to access chiral lactams. A range of polycyclic nitrogen-containing scaffolds were obtained in good yields with excellent enantioselectivity. Further derivatization of the lactam products led to a rapid entry to various novel fused heterocycles

The critical point <i>p</i>_<i>c</i> versus <i>β</i>.

<p>In the simulation, the network size is set as 20000 and the average degree is ⟨<i>k</i>⟩ = 6. The dependence group sizes are set as <i>g</i> = 5 (square) and <i>g</i> = 10 (star). The solid and dash lines are the corresponding theoretical prediction of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126674#pone.0126674.e018" target="_blank">Eq (12)</a> for the first order transition region, and the dot lines for the second order transition region. As discussed in the text, the curve of the critical point </p><p></p><p></p><p><mi>p</mi><mi>c</mi><mi>I</mi></p><p></p><p></p> is discontinuous at <i>β</i> = <i>n</i>/<i>g</i>, <i>n</i> = 1, 2, 3, …, <i>g</i> −1. For <i>β</i> > (<i>g</i> − 1)/<i>g</i>, the system demonstrates a continuous phase transition. In addition, the critical points of the networks with large dependence group sizes are not always larger than those with small group sizes. This means dependence group size is not the sole factor determining the robustness of such networks.<p></p

Networks with conditional dependence groups.

<p>The network is composed of nodes and connectivity links, and each node belongs to a dependence group (surrounded by dash lines). In each group, if more than a fraction <i>β</i> of nodes fail, the group will fail, i.e., all the nodes of this group fail. Take <i>β</i> = 0.5 as an example. In the group formed by nodes 5, 8 and 9, when node 9 fails, nodes 5 and 8 will still work since the fraction of failed nodes is less than <i>β</i>. However, if nodes 5 and 9 fail simultaneously, node 8 must also fail. This model can also be described by the load model used in ref.[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126674#pone.0126674.ref015" target="_blank">15</a>], this article does not cover details of this model.</p

Enantioselective Rh-Catalyzed Carboacylation of CN Bonds via C–C Activation of Benzocyclobutenones

Herein we describe the first enantioselective Rh-catalyzed carboacylation of oximes (imines) via C–C activation. In this transformation, the benzocyclobutenone C1–C2 bond is selectively activated by a low valent rhodium catalyst and subsequently the resulting two Rh–C bonds add across a CN bond, which provides a unique approach to access chiral lactams. A range of polycyclic nitrogen-containing scaffolds were obtained in good yields with excellent enantioselectivity. Further derivatization of the lactam products led to a rapid entry to various novel fused heterocycles

The results of ER networks with 20000 nodes for different <i>g</i>.

<p>In the simulation, the parameters are set as: ⟨<i>k</i>⟩ = 6, <i>g</i> = 5 (solid symbols) and <i>g</i> = 10 (empty symbols). (a) The size of the giant component <i>S</i> versus <i>p</i>, the fraction of nodes that have been left after random removal. The symbols represent simulation results, and the solid lines show the corresponding analytical predictions of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126674#pone.0126674.e010" target="_blank">Eq (9)</a>. When <i>β</i> = 0.15, 0.35, networks become more robust with <i>g</i> increaseing. However, for <i>β</i> = 0.45, 0.65, networks become more fragile with <i>g</i> increaseing. (b) NOI sharply increases when <i>p</i> approaches the critical point, so the sharp peaks can identify the corresponding critical points </p><p></p><p></p><p><mi>p</mi><mi>c</mi><mi>I</mi></p><p></p><p></p> for the first order transition region.<p></p