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Silicon nitride (SiN) is one of the emerging semiconductor materials that are used in both linear and nonlinear all-optical integrated devices. Its excellent dielectric properties, high material stability, and dispersion controllability are attractive to on-chip optical communications, optical signal processing, and even imaging devices. However, a large-aperture SiN metalens with high numerical aperture (NA) is limited by the low refractive index and nanofabrication technologies, particular in the visible spectrum. Here, we experimentally realize the visible-spectrum SiN divergent metalenses by fabricating the 695-nm-thick hexagonal arrays with a minimum space of 42 nm between adjacent nanopillars. A micro-size divergent metalens with NA∼0.98 and subwavelength resolution enables objects to be shrunk as small as a single-mode fiber core. Another centimeter-size SiN divergent metalens with over half a billion nanopillars, made by using the mature CMOS-compatible fabrication process, exhibits high-quality wide-angle imaging. Our findings may open a new door for the miniaturization of optical lenses in the fields of optical fibers, microendoscopes, and smart phones, as well as the applications in all-sky telescopes, large-angle beam shaping, and near-eye imaging.

The reactions of methyl-4-(pyrimidin-2-ylcarbamoyl)benzoate ( L ) with Co(II), Ni(II), Cu(II) and Cu(I) metal salts afforded [Co( L ) 2 (CH 3 OH) 2 ](ClO 4 ) 2 ( 1 ), [Co( L ) 2 (CH 3 OH) 2 ](BF 4 ) 2 ( 2 ), [Ni( L ) 2 (CH 3 OH) 2 ](BF 4 ) 2 ( 3 ), [Cu( L ) 2 (ClO 4 ) 2 ]·2CH 3 OH ( 4 ), [Cu( L ) 2 (BF 4 ) 2 ]·2CH 3 OH ( 5 ), [Cu( L ) 2 Br 2 ]·CH 3 OH ( 6 ), [Cu 2 ( L )Cl 4 ·CH 3 CN] ∞ ( 7 ), [Cu 3.5 ( L )Br 4 ·0.5C 2 H 5 OC 2 H 5 ] ∞ ( 8 ) and [Cu 2 ( L )I 2 ] ∞ ( 9 ), which have been structurally characterized by X-ray crystallography. Four types of ligand conformation-coordination mode, cis -bidentate, cis -tridentate, trans -bidentate and trans -tridentate, are observed for the L ligand in these complexes, resulting in mononuclear structures for 1 – 6 , layer structures for 7 and 8 and a chain structure for 9 . C–H⋯π and π⋯π interactions and various hydrogen bonds are found in these complexes that extend the dimensionalities of the structures, and the structural types of the copper halide aggregates in 7 – 9 are unique.

With nonlinear fluorescence technique we have generated various stable filaments under excitation of femtosecond laser pulses from a Ti: sapphire system. The dynamic evolution of the filamentation has been measured and the corresponding mechanism has also been discussed. Especially, the generation of multiple filaments has been simulated numerically based on the linear diffraction effect of the aperture, which would enrich the study of the filament propagation of ultra-short laser pulses in complicated liquid media.

By using isomeric N,N′-di(2-pyridyl)adipoamide (L1), N,N′-di(3-pyridyl)adipoamide (L2) and N,N′-di(4-pyridyl)adipoamide (L3) and isomeric 1,2-benzenedicarboxylic acid (1,2-H2BDC), 1,3-benzenedicarboxylic acid (1,3-H2BDC) and 1,4-benzenedicarboxylic acid (1,4-H2BDC), eight Zn(II) and Cd(II) coordination polymers [Zn(1,2-BDC)(L2)]∞, 1; [Zn2(1,3-BDC)2(L2)(H2O)2]∞, 2; [Zn2(1,4-BDC)2(L1)(H2O)2]∞, 3; {[Zn2(1,2-BDC)2(L3)(H2O)2]·2H2O}∞, 4; {[Cd(1,2-BDC)(L2)(H2O)]·H2O}∞, 5; [Cd2(1,3-BDC)2(L2)(H2O)4]∞, 6; {[Cd2(1,4-BDC)2(L2)2]·(H2O)3}∞, 7; [Cd2(1,4-BDC)2(L1)(H2O)2]∞, 8, have been synthesized under hydrothermal conditions. Complexes 1, 4, and 5 form 1D double-looped chain, 1D chain with loops and 2D layer with loops, respectively, and complex 6 exhibits a 1D ladder chain. Complex 2 shows rare 3-fold interpenetrated hcb layers, in which each layer interdigitates with other four parallel layers by directing the 1,3-BDC ligands into the windows of the adjacent nets, whereas complexes 3 and 8 forms planar and undulated ...

To explore how to remove CT ring-shaped artifact quickly and effectively, and to improve accuracy of CT reconstruction image.CT graphics (including the ring-shaped artifacts) were used first in coordinate transformation with a new transformation method. A two-dimensional filter was designed to filter the image. Then, a one-dimensional filter was used to re-filter the image. Finally, a new transform method was used to restore the image.The two-step coordinate transformation of ring-shaped artifact algorithm resulted in accurate restored original CT image, effectively reducing its interference on useful information.The method described in this study can overcome disadvantages of existing methods and obtain good results.

A "basophilic method" for phenolic hydroxyl bridged lanthanide coordination polymers (CPs) was developed. With this method, eleven CPs with the general formula of [Ln(HL1)L1·H(2)O](n) (Ln = Tb (1), Nd (2), Eu (3), Gd (4), La (5), Er (6), Y (7), H(2)L1 = 4-methyl salicylic acid) and [Ln(HL2)L2·2MeOH](n) (Ln = Eu (8), Tb (9), Gd (10), La (11), H(2)L2 = 3-hydroxy-2-naphthoic acid) were synthesized based on two ligands, and five of them (1-4 and 8) were characterised by X-ray single crystal diffraction. The powder X-ray diffraction patterns (PXRD) of complexes showed that 1-7 are isostructural, 8-11 are isostructural. Furthermore, 1 was characterised by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), elemental analysis (EA), one and two photon luminescence were investigated in detail.

The first complex picosecond filament, namely a filament of terbium(III) p-hydroxybenzoate, is observed. The filament is the only example of Ln(III) ion two-photon absorption in a complex. A transparent, colorless and mechanically robust thin film, as well as a supramolecular gel, of this complex are prepared in a facile manner and exhibit strong luminescence. The thin film is characterized in detail by XRD, SEM, UV-vis, luminescence spectroscopy and lifetime.

By now, there are many recognition methods. Support vector machine (SVM) is one of main methods. For SVM, the training time was long and it was hard to implement large-scale samples' training, so the training model of SVM and the recognition to the testing are influenced directly. In order to solve these problems, this paper provided an optimized algorithm based on Gustafson-Kessel (G-K) fuzzy clustering of training sample set, and it studied the automatic recognition of stratiform /cumuliform cloud. In the paper, the cloud areas were extracted, and the data were refined with clustering. Finally, the stratiform /cumuliform clouds were identified with SVM. The experiments showed that the training sample scale was reduced by six and the training time of SVM was reduced from 31ms to 16ms after Gustafson-Kessel clustering. The recognition rate was greatly increased from 78% to 86% with the optimized algorithm.

As the nanostructure fabrication technology improves, patterns and structures of several hundred nanometer can be obtained now. Since the size of the particle or the ripple is in the same scale as the wavelength of visible light, this paper uses Mie theory to analyze the light energy scattered by the nanostructure. The light extraction efficiency enhancement, as well as the angular distribution of the scattered light intensity at different wavelengths of the incidence light, is studied in this article. The simulation result is consistent with the experiment. Semi- quantitative and qualitative discussion in theory is also given in this work. x a n n n n n n n n n

Cloud is the basis of precipitation, and the precipitation caused by stratiform clouds is wide-scale and continuous, which exerts an important impact on agriculture, navigation, spaceflight and so on. At present, there is no mature specific equipment or technology internationally to automatically recognize the cloud form. By extracting the cloud area and using the Gabor filter to extract the texture feature value. This paper uses support vector machine to identify the stratiform clouds, and analyzed and compared the various parameters of the support vector machine. By computer simulation, it shows that identification of stratiform clouds based on texture features extracted by Gabor with support vector machines has a high recognition rate.

Reactions of the flexible N,N′-di(3-pyridyl)dodecanediamide (L) with Zn(II) and Cd(II) metal salts in the presence of different polycarboxylic acids under hydrothermal conditions afforded five new coordination polymers, [Zn(2,4-PDC)(L)(H2O)]∞ (2,4-H2PDC = 2,4-pyridinedicarboxylic acid), 1, {[Zn(1,3,5-HBTC)(L)]·2H2O}∞ (1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid), 2, {[Zn(3,4-PDC)(L)]·0.5L}∞ (3,4-H2PDC = 3,4-pyridinedicarboxylic acid), 3, {[Cd(1,2-BDC)(L)(H2O)]·0.5L}∞ (1,2-H2BDC = 1,2-benzenedicarboxylic acid), 4, and {[Cd(1,3,5-HBTC)(L)1.5]·2H2O}∞, 5, which have been structurally characterized by X-ray crystallography. Complexes 1 and 2 manifest quintuple and double helices formed by zinc ions and L ligands, which are supported by 2,4-PDC2− and 1,3,5-HBTC2− anions, respectively, to construct the rare single-walled metal–organic nanotubes. Complex 3 shows 1D fish-bone chains and complexes 4 and 5 display 2D pleated grids with helical and looped carboxylate chains, respectively, supported by the L ligands. Complexes 1–3 represent a unique example of the polycarboxylate ligands showing a significant effect on folding and unfolding of the Zn(II) helical coordination polymers, and they are also important in determining the number of helices. The L ligands in 1, 2 and 4 adopt a bidentate bonding mode, and a unique monodentate bonding mode for the dipyridyl amide ligand is found in 3 and 5, resulting in various types of ligand conformations.

Eight new Zn(II) and Cd(II) coordination networks containing N,N′-di(3-pyridyl)adipoamide (L) and polycarboxylate ligands, {[Zn2(2,5-PDC)2(L)(H2O)2]·2H2O}∞ (H2PDC = 2,5-pyridinedicarboxylic acid), 1, [Zn2(2,6-PDC)2(L)]∞, 2, {[Zn2(3,4-PDC)2(L)(H2O)6]·4H2O}∞, 3, {[Cd(2,6-PDC)(L)(H2O)]·4H2O}∞, 4, [Zn(1,3,5-HBTC)()]∞ (H3BTC = benzenetricarboxylic acid), 5, {[Cd(1,2,3-HBTC)(L)(H2O)]·H2O}∞, 6, {[Cd2(1,3,5-HBTC)2(L)(H2O)2]·2H2O}∞, 7, and {[Zn3(1,2,4-BTC)2(L)(H2O)4]·4H2O}∞, 8, have been synthesized by hydrothermal reactions and characterized by single crystal X-ray crystallography. Structural analysis reveals that 1 and 2 form pleated hcb layers with 1D helical chains, in which the layers of 1 interdigitate with each other and those of 2 are linked by the π–π stacking interactions. Complexes 3 and 4 exhibit 1D ladders with single and double rungs, respectively, whereas 5 shows a 2D pleated net with the sql topology, 6 displays a 3D dia coordination network and 7 forms a 2D structure with the (63)(66)-3,4L88 topology. The BTC3− ligands in 8 adopt the μ4-bonding modes, resulting in a 3D coordination network with the rare (65·8)-hxg-d-4-P2/c topology. The various bonding modes, the ligand-isomerism of the polycarboxylate ligands and the identity of the metal center play important roles in determining the structural diversity. Their thermal and luminescent properties are also discussed.

Reactions of silver(I) salts with the isomeric pyridyl amide ligands methyl-4-(pyridin-2-ylcarbamoyl)benzoate (L1), methyl-4-(pyridin-3-ylcarbamoyl)benzoate (L2) and methyl-4-(pyridin-4-ylcarbamoyl)benzoate (L3) and the pyrimidyl amide ligand methyl-4-(pyrimidin-2-ylcarbamoyl)benzoate (L4) afforded the complexes Ag4(L1)4(NO3)4, 1, [Ag(L2)2][Ag(NO3)2], 2, [Ag(L2)2](ClO4), 3, [Ag(L2)2](ClO4)·2CH3CN, 4, [Ag(L3)2](NO3), 5, [Ag(L3)2](ClO4)·CH3CN, 6, and [Ag(L4)2](X) (X = ClO4−, 7; BF4−, 8; PF6−, 9), which were structurally characterized by X-ray crystallography. The L1–L3 ligands in 1–6 adopt monodentate bonding modes, which coordinate to the metal centers through the pyridyl nitrogen atoms, whereas the L4 ligands of 7–9 adopt a bidentate mode, featuring chelation through one pyrimidyl nitrogen atom and the amide oxygen atom. All nine complexes adopt discrete structures with 1 being tetranuclear and 2–9 being mononuclear. Moreover, Ag⋯Ag short contacts, π⋯π stacking interactions and/or Ag⋯O interactions are found in these complexes which extend the dimensionalities of the structures. The changes of the donor atom positions and counteranions significantly affect the supramolecular structures of these complexes and the L1–L4 ligands are sufficiently flexible to adopt the cis and/or trans conformations.