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Slow-release fertilizer was developed by encapsulating NPK compound pellets with graphene oxide (GO) sheets employing a waterless synthesis technique. As-prepared GO sheets were characterized by XRD, Raman, XPS, FTIR, SEM, and EDS. The XRD patterns of the GO sheets indicate that the peak for the GO is observed at 2θ = 9.3°, and the peak (002) for graphite vanished. Moreover, a higher intensity ratio of the Raman ID/IG of the GO sheets than that of pristine graphite confirms the oxidation of the graphite. The FTIR and XPS analyses provided information on electronic structure, chemical structure, and oxygen-bonding neighbors. The SEM images indicated the GO sheet, whereby its morphology resembles a thin curtain or corrugated shape. The EDS spectrum of coated GO-F pellets revealed the distribution of C, O, N, P, and K elements in the synthesized materials. Afterwards, GO shell formation on fertilizer pellets greatly improved the slow-release characteristics of fertilizer, thus providing plants with their requisite nutrients and reducing environmental pollution. [ABSTRACT FROM AUTHOR]

We propose a scheme to investigate the spatial modulation of the refractive index in a dense atomic ensemble under the action of the Laguerre–Gaussian (LG) beams. Theoretical derivations based on a density-matrix approach associated with numerical simulations are utilized to study the behaviors of the index of refraction, showing that the azimuthal and radial mode indices (i.e., l 2 and p 2) of the LG beams significantly affect the real and imaginary parts of the refractive index. To be specific, the number of the dispersive peaks is determined by (p 2 + 1) | l 2 | , and there are 2 | l 2 | lossless petals in conjunction with p 2 concentric absorption rings centered on the vortex center. Furthermore, by tuning the phase values of the electric and magnetic components of the electromagnetic field, the index of refraction can be drastically tuned from negative to zero to positive and accompanied by periodic absorption and amplification. This investigation provides a powerful tool for manipulating the index of refraction through a nonlinear interaction between atoms and the vortex beams and suggests potential applications in optical switching, logic gates, and optical storage with spatially varying refractive indices. [ABSTRACT FROM AUTHOR]

Vinyl-capped cationic waterborne polyurethane (CWPU) was prepared using isophorone diisocyanate (IPDI), polycarbonate diol (PCDL), N-methyldiethanolamine (MDEA), and trimethylolpropane (TMP) as raw materials and hydroxyethyl methacrylate (HEMA) as a capping agent. Then, a crosslinked FPUA composite emulsion with polyurethane (PU) as the shell and fluorinated acrylate (PA) as the core was prepared by core-shell emulsion polymerization with CWPU as the seed emulsion, together with dodecafluoroheptyl methacrylate (DFMA), diacetone acrylamide (DAAM), and methyl methacrylate (MMA). The effects of the core-shell ratio of PA/PU on the surface properties, mechanical properties, and heat resistance of FPUA emulsions and films were investigated. The results showed that when w(PA) = 30~50%, the stability of FPUA emulsion was the highest, and the particles showed a core-shell structure with bright and dark intersections under TEM. When w(PA) = 30%, the tensile strength reached 23.35 ± 0.08 MPa. When w(PA) = 50%, the fluorine content on the surface of the coating film was 14.75% and the contact angle was as high as 98.5°, which showed good hydrophobicity; the surface flatness of the film was observed under AFM. It is found that the tensile strength of the film increases and then decreases with the increase in the core-shell ratio and the heat resistance of the FPUA film is gradually increased. The FPUA film has excellent properties such as good impact resistance, high flexibility, high adhesion, and corrosion resistance. [ABSTRACT FROM AUTHOR]

Dynamic control of probe absorption spectrum via vortex beams in multilevel systems has attracted much attention because it provides an avenue to observe unique transport properties. In this paper, we employ experimentally accessible parameters to flexibly control the probe absorption spectrum that shows vortex-induced transparency (VIT) and absorption (VIA) phenomena. Specifically, this system can be served as an optical switch while the vortex beams can act as the control knob, which has the ability to switch from a transparency dip to an absorption peak. Differing from a conventional electromagnetically induced transparency technique, our proposed scheme investigates VIT and VIA by tuning the orbital angular momentum of vortex beams in the resonance and non-resonance cases. Moreover, the collective feature caused by constructive or destructive interference is also studied via adjustable frequency detuning. Our results may provide an efficient approach to study similar phenomena in multilevel quantum systems driven by optical vortex beams. [ABSTRACT FROM AUTHOR]

Nonlocal dispersion cancellation is one of the non-classical effects of quantum entangled photon sources, and it has important applications in quantum information science. A detailed introduction to the concept, research significance of nonlocal dispersion canceUation, and the research progress in China and abroad in recent years were reviewed. The foUowing three cases: the nonlocal dispersion canceUation of frequency entangled photon sources, the nonlocal dispersion canceUation in Franson interferometers, ad the local dispersion canceUation in the Hong-Ou-Mandel interferometer were then compared and analyzed. On this basis, the prospects for the study of quantum dispersion cancellation were anticipated. [ABSTRACT FROM AUTHOR]

A new Zn-based metal–organic framework with 8-connected hex topology constructed from bipyridine and carboxylate ligands, namely [Zn(cpna)3(tmbpy)]n·4DMF (1) (H2cpna = 6-(4-carboxyphenyl)nicotinic acid; tmbpy = 3,3′-dimethyl-4,4′-bipyridine), has been synthesized under solvothermal conditions. The Zn-MOF was structurally characterized and retained a good crystal structure after activation (1a), an indication of permanent porosity. 1a exhibits a BET surface of 770 m2 g−1 and the maximum aperture of 8.60 Å. Single component adsorption isotherm measurements of C2H2, CO2, CH4, CO and N2 on 1a were performed both at 273 K and 298 K, and the selectivities for C2H2/CH4, C2H2/CO2, CO2/CO, CO2/CH4 and CO2/N2 were estimated on the basis of the ideal adsorbed solution theory (IAST). 1a shows the uptake of C2H2 (3.89 mmol g−1) and CO2 (3.52 mmol g−1) at 273 K and 100 kPa, respectively. Due to the Lewis basic pyridyl sites inside the channel of the framework, 1a showed good adsorption selectivities for C2H2/CH4(50 : 50) and C2H2/CO2(50 : 50) at 298 K (100 kPa). [ABSTRACT FROM AUTHOR]