Optical solitons and complexitons of the Schrödinger–Hirota equation

The Schrödinger–Hirota equation governs the propagation of optical solitons in a dispersive optical fiber. In this paper, this equation will be solved by the ansatz method for bright and dark 1-soliton solution. The power law nonlinearity will be assumed. By using the tanh method, some additional solutions will be derived. Finally, the numerical simulations will be given.     

Morphology dependent luminescence properties of rare-earth doped lanthanum fluoride hierarchical microstructures

Here, we demonstrate an ionic liquid-assisted hydrothermal method for preparing Tb³⁺ and Eu³⁺ doped LaF₃ hierarchical microstructures and the morphology is modified by hydrothermal reaction time, temperature of heating and ionic liquid concentration. The mechanism related to morphology control is proposed and discussed. It is also found that PL intensity, decay time and quantum efficiency are sensitive to the morphology. The average decay times are 2.9 ms and 4.8 ms for Eu³⁺ doped LaF₃ microstructures prepared at 10 min and 3 h reaction time, respectively. The average decay time is increased from 4.8 ms to 5.8 ms after heating the sample at 500 °C. The quantum efficiency varies from 34% to 67% with changing morphology. Analysis suggests that morphology plays an important role on efficiency of rare-earth doped materials.     

Influence of Substituent and Solvent on the Radiative Process of Singlet Excited States of Novel Cyclic Azacyanine Derivatives

The photophysical properties of novel cyclic azacyanine derivatives have been investigated in acetonitrile, N-butyronitrile, methanol, ethanol, DMF and water. Introduction of electron donating or accepting groups on the cyclic azacyanine has a direct impact on the spectroscopic and photophysical properties. Irrespective of the nature of the substitution, azacyanine shows a general solvent relaxation in accordance with Lippert-Mataga’s prediction; however, in protic solvent, specific interactions are encountered. Fluorescence lifetime decay suggests a relaxation in the nanosecond time scale with monoexponential decay in polar solvents and biexponential decay in non polar solvents. The fluorescence lifetime of azacyanines are found to be longer than popular cy3 dyes. An electron donating substituent increases the fluorescence lifetime and influences the radiative process, whereas an electron withdrawing group marginally increases the excited state lifetime but remarkably enhances the radiative process. The fluorescence quantum yield of substituted cyclic azacyanine in water is noted to be at least five fold higher than the popular cy3 dye.     

Effect of Paulownia Leaves Extract Levels on In Vitro Ruminal Fermentation,Microbial Population,Methane Production,and Fatty Acid Biohydrogenation

Paulownia is a fast-growing tree that produces a huge mass of leaves as waste that can be used as a feed source for ruminants. The previous study showed that phenolic compounds were the most active biological substances in Paulownia leaves, which affected the ruminal parameters and methane concentration. However, there are no scientific reports on the Paulownia leaves extract (PLE) containing phenolic compounds for their mode of action in the rumen. Phenolics constituted the main group of bioactive compounds in PLE (84.4 mg/g dry matter). PLE lowered the concentration of ammonia, modulated the VFA profile in the ruminal fluid, and decreased methane production. The PLE caused a significant reduction of in vitro dry matter degradability, reduced the number of methanogens and protozoa, and affected selected bacteria populations. PLE had a promising effect on the fatty acid profile in the ruminal fluid. Paulownia as a new dietary component or its extract as a feed additive may be used to mitigate ruminal methanogenesis, resulting in environmental protection and reducing ruminal biohydrogenation, improving milk and meat quality.     

Electron-Driven Nitration of Unsaturated Hydrocarbons

Herein, we introduce an electrochemically assisted generation of nitryl radicals from ferric nitrate under mild reaction conditions using a simple setup with inexpensive graphite and stainless-steel electrodes. The mechanism of the reaction is supported by detailed spectroscopic and experimental studies. Powered by electricity and driven by electrons, the synthetic diversity of this reaction has been demonstrated through the development of highly efficient nitration protocols of various unsaturated hydrocarbons. In addition to a broad application area, these protocols are easy to scale for decagram quantities, and exhibit exceptional substrate generality and functional-group compatibility.     

Transformation of an Imine Cage to a Covalent Organic Framework Film at the Liquid–Liquid Interface

Dynamic covalent chemistry (DCC) opens up a fascinating route for the construction of well-organized supramolecular architectures, starting from organic molecular cages to crystalline macromolecular covalent organic frameworks (COFs). Herein, for the first time, we have manifested a facile room-temperature DCC-directed transformation of discrete organic imine cage-to-COF film at the liquid–liquid interface. The unfolding of the cage leading to the generation of imine intermediates, followed by their interface-assisted preorganization and subsequent growth of the COF film, are elucidated through detailed spectroscopic and microscopic investigations. The interfacial cage-to-COF transformation provides a facile route for the faster fabrication of free-standing COF films with high porosity and crystallinity, demonstrating excellent performance towards molecular sieving and high solvent permeance. Thus, the current study opens up a new route for structural interconversion between two crystalline entities with diverse dimensionality employing DCC at the confined interface.     

Realization of Z2 Topological Metal in Single-Crystalline Nickel Deficient NiV2Se4

Temperature-dependent electronic and magnetic properties are reported for nickel-deficient NiV₂Se₄. Single-crystal X-ray diffraction shows it to crystallize in the monoclinic Cr₃S₄ structure type with space group $I2/m$ and vacancies on the Ni site, resulting in the composition Ni_0.85V₂Se₄ in agreement with our electron-probe microanalysis. Structural distortions are not observed down to 1.5 K. Nevertheless, the electrical resistivity shows metallic behavior with a broad anomaly around 150–200 K that is also observed in the heat capacity data. This anomaly indicates a change of state of the material below 150 K. It is believed that this anomaly could be due to spin fluctuations or charge-density-wave fluctuations, where the lack of long-range order is caused by vacancies at the Ni site of Ni_0.85V₂Se₄. The non-linear temperature dependence of the resistivity as well as an enhanced value of the Sommerfeld coefficient $\gamma =104.0(1)$ mJ mol⁻¹ K⁻² suggest strong electron–electron correlations in this material. First-principles calculations performed for NiV₂Se₄, which are also applicable to Ni_0.85V₂Se₄, classify this material as a topological metal with $Z_2=(1;110)$ and coexisting electron and hole pockets at the Fermi level. The phonon spectrum lacks any soft phonon mode, consistent with the absence of periodic lattice distortion in the present experiments.     

UV-to-NIR Harvesting Conjugated Porous Polymer Nanocomposite: Upconversion and Plasmon Expedited Thioether Photooxidation

Photocatalysts capable of harvesting a broad range of the solar spectrum are essential for sustainable chemical transformations and environmental remediation. Herein, we have integrated NIR-absorbing upconversion nanoparticles (UCNP) with UV-Vis absorbing conjugated porous organic polymer (POP) through the in situ multicomponent C−C coupling to fabricate a UC−POP nanocomposite. The light-harvesting ability of UC−POP is further augmented by loading plasmonic gold nanoparticles (AuNP) into UC−POP. A three-times enhancement in the upconversion luminescence is observed upon the incorporation of AuNP in UC−POP, subsequently boosting the photocatalytic activity of UC−POP−Au. The spectroscopic and photoelectrochemical investigations infer the enhanced photocatalytic oxidation of thioethers, including mustard gas simulant by UC−POP−Au compared to POP and UC−POP due to the facile electron-hole pair generation, suppressed exciton recombination, and efficient charge carrier migration. Thus, the unique design strategy of combining plasmonic and upconversion nanoparticles with a conjugated porous organic polymer opens up new vistas towards artificial light harvesting.