Synthesis of nano‐sized magnetite mesoporous carbon for removal of Reactive Yellow dye from aqueous solutions

In this study, core‐shell structures of magnetite nanoparticles coated with CMK‐8 ordered mesoporous carbon (Fe₃O₄@SiO₂‐CMK‐8 NPs) have been successfully synthesized for the first time by carbonizing sucrose inside the pores of the Kit‐6 mesoporous silica. The nano‐sized mesoporous particles were characterized by X‐ray diffraction, Fourier transform‐infrared spectroscopy, scanning electron microscope, dynamic light scattering, vibrating‐sample magnetometer, Brunauer–Emmett–Teller (BET) and transmission electron microscopy instruments. The obtained nanocomposite was used for removal of Reactive Yellow 160 (RY 160) dye from aqueous samples. The N₂ adsorption–desorption method (at 77 K) confirmed the mesoporous structure of synthesized Fe₃O₄@SiO₂‐CMK‐8 NPs. Also, the surface area was calculated by the BET method and Langmuir plot as 276.84 m²/g and 352.32 m²/g, respectively. The surface area, volume and pore diameter of synthesized nanoparticles (NPs) were calculated from the pore size distribution curves using the Barrett–Joyner–Halenda formula (BJH). To obtain the optimum experimental variables, the effect of various experimental parameters on the dye removal efficiency was studied using Taguchi orthogonal array experimental design method. According to the experimental results, about 90.0% of RY 160 was removed from aqueous solutions at the adsorbent amount of 0.06 g, pH 3 and ionic strength = 0.05 m during 10 min. The pseudo‐second order kinetic model provided a very good fit for the RY 160 dye removal (R² = 0.999). The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the equilibrium isotherms, and the Langmuir isotherm showed the best fit to data with the maximum adsorption capacity of 62.893 mg/g. Furthermore, the Fe₃O₄@SiO₂‐CMK‐8 NPs could be simply recovered by external magnet, and exhibited recyclability and reusability for a subsequent six runs.     

Synthesis of star-shaped CuO nanoparticles supported on magnetic functionalized graphene: Catalytic and antibacterial activity

In this study, graphene oxide was modified during consecutive functionalization steps with 1,4-diphenylamine, cyanuric chloride, and ethylenediamine. Then, star-shaped CuO nanoparticles were synthesized on modified graphene oxide using the seed-mediated growth method in which nucleation, growth stages, and reduction of graphene oxide to graphene occurred simultaneously. After ensuring successful synthesis of CuO nanoparticles and to facilitate recycling, a magnetization process was utilized by adding iron oxide nanoparticles. This nanocomposite was characterized by transmission electron microscopy, X-ray powder diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The prepared heterogeneous catalyst was investigated for the reduction of organic dyes in the presence of NaBH₄ as a reducing reagent. The kinetic data obtained for the reduction of methyl orange (MO), methylene blue (MB), 4-nitrophenol (4-NP), and rhodamine 6G (Rh6G) were fitted to first-order rate equations, and the calculated rate constants for the reduction of MO, MB, 4-NP and Rh6G were as follows: −0.091, −0.071, −0.045, and 0.040, respectively. As star-shaped CuO nanoparticles showed a higher antibacterial effect compared to spherical-shaped CuO nanoparticles, the antibacterial activity of star-shaped CuO nanoparticles immobilized on magnetic functionalized graphene was evaluated against Gram-positive and Gram-negative bacteria through an agar well diffusion assay and demonstrated more antibacterial activity against gram-positive bacteria.     

Preparation and characterization of a novel water soluble amino chitosan (amino-CS) derivative for facilitated transport of CO<Subscript>2</Subscript>

With the goal of obtaining a water soluble polymeric carrier for preparation of fixed facilitated transport membranes, a water soluble amino containing chitosan derivative was prepared through Michael-addition reaction between chitosan and ethyl acrylate followed by amidation of the ester groups with an appropriate diamine. This derivative was characterized using ¹H-NMR spectroscopy. Then, facilitated transport membranes were prepared by casting a thin layer of chitosan derivative/poly(vinyl alcohol) blend on a porous polysolfune support; and the effect of fixed carrier’s content, feed temperature and feed pressure on the CO₂ permeance, and CO₂/CH₄ selectivity of produced membranes were studied. A facilitated transport mechanism for CO₂ through this membrane was concluded.     

Towards experiments with highly charged ions at HESR

The atomic physics collaboration SPARC is a part of the APPA pillar at the future Facility for Antiproton and Ion Research. It aims at atomic-physics research across virtually the full range of atomic matter. An emphasis of this contribution are the atomic physics experiments addressing the collision dynamics in strong electro-magnetic fields as well as the fundamental interactions between electrons and heavy nuclei at the HESR. Here we give a short overview about the central instruments for SPARC experiments at this storage ring.     

Introducing boranorcaradienes with more stability than their corresponding borepins: Reversal of tautomerization via substituents at theoretical levels

In contrast to typical borepins, which appear about 40.0 kcalmol^?1 more stable than their corresponding tautomeric boranorcaradienes, we have found 2 species, which have reversed this trend and pushed the equilibrium in favor of their corresponding boranorcaradienes. They are namely 1a,9b‐dihydro‐1H‐borireno[2,3‐h]pyridazino[4,3‐f]cinnoline and 1a,9b‐dihydro‐1H‐borireno[2,3‐h]pyrimido[5,4‐f]quinazoline which stand up among 14 isomeric systems probed, at B3LYP/AUG‐cc‐pVTZ, M06‐2X/AUG‐cc‐pVTZ, MP2/AUG‐cc‐pVTZ, and HF/AUG‐cc‐pVTZ. Energy barriers are calculated in gas‐phase, where the possibility of a rapid interconversion of the isomers is ruled out. Generally, dibenzoboranorcaradienes assume C_s symmetry with planar geometry and dihedral angle of zero degree. In contrast, their corresponding borepins show a high tendency for puckering with dihedral angle of ~66°. The preference of the latter for puckered non‐planar geometries is evidenced by natural bonding orbitals calculations and visually through their frontier molecular orbitals. Main interactions appear to be hyperconjugations of σ and π bonds across the rings. Position and number of nitrogen atoms on the fused rings seem to affect the energy gap, dipole moment, symmetry, dihedral angle, the chemical shift, NICS, bond lengths, and charge distribution.     

Potassium-intercalated H(2)Pc films: Alkali-induced electronic and geometrical modifications

X-ray spectroscopy studies of potassium intercalated metal-free phthalocyanine multilayers adsorbed on Al(110) have been undertaken. Photoelectron spectroscopy measurements show the presence of several charge states of the molecules upon K intercalation, due to a charge transfer from the alkali. In addition, the comparison of valence band photoemission spectra with the density functional theory calculations of the density of states of the H(2)Pc(-) anion indicates a filling of the formerly lowest unoccupied molecular orbital by charge transfer from the alkali. This is further confirmed by x-ray absorption spectroscopy (XAS) studies, which show a decreased density of unoccupied states. XAS measurements in different experimental geometries reveal that the molecules in the pristine film are standing upright on the surface or are only slightly tilted away from the surface normal but upon K intercalation, the molecular orientation is changed in that the tilt angle of the molecules increases.     

Lack of anomalous diffusion in linear translationally-invariant systems determined by only one initial condition

It is shown that as far as the linear diffusion equation meets both time- and space-translational invariance, the time dependence of a moment of degree α is a polynomial of degree at most equal to α, while all connected moments are at most linear functions of time. As a special case, the variance is an at most linear function of time.     

Statistical Characteristics of an Isothermal, Supersonic Developing Boundary Layer Flow from DNS Data

Direct numerical simulation results for a developing, supersonic boundary layer flow with either an adiabatic wall temperature condition or a cold wall (relative to adiabatic) temperature condition are evaluated to assess the comparative effect on the mean and turbulent fields. Included in the analysis are two-point turbulent spanwise spatial correlations and the corresponding one-dimensional energy spectra distributions as well as higher-order statistics including skewness and flatness factors. In addition to the mean field velocity and temperature behavior, the turbulent Reynolds stress, temperature variance, and heat and mass flux distributions are discussed. An overall focus of the analysis is to both contrast the velocity and thermal field behavior and to provide some additional insight into the dynamic balance of the various statistical correlations and their impact on model development.