A new method for preparing TiO2 catalyst honeycombs without sintering

Composite catalyst honeycombs without sintering were prepared via kneading, mulling, extrusion molding, and solidifying at room temperature with the magnesite oxychloride gels modified by nano-rice husk ash (RHA) as a solidifying agent. The effects of nano-RHA and composite water-resistant agents on the water resistance of magnesite materials were studied. The solidification of the modified magnesite gels on TiO₂ catalyst honeycombs was analyzed. The experiments show that the proportional addition of nano-RHA markedly increases the water resistance of magnesite materials without reducing the bending strength, and the softening coefficient increases from 0.29 to 0.78. With further addiition of the complex water-resistant agents, the softening coefficient increases from 0.78 to 0.97. The optimal mass ratio of MgO in the solidifying agent to TiO₂ is 4:1, and the bending strength of unsintered catalyst honeycombs is 11.46 MPa. The desulfurization rate and denitration rate of this composite catalyst honeycomb on simulation smoke was 97 and 65 %, respectively, in 3 h.     

Rheological Technique as a Sensitive Method to Characterize the Chain Diffusion across the Interface between Polystyrene and Carbon Black Filled Polystyrene

The mutual diffusion process and interphase development taking place at the interface between disks of polystyrene (PS) and carbon black filled polystyrene (CB-PS) in the molten state were investigated by a small-amplitude, oscillatory shear, rheological technique. The rheological method was employed to probe the thermorheological complexity of these polymer disks. It was found that the dynamic complex shear modulus, G*(t), increased with the time of contact in two time regimes at a fixed frequency. The time of transition between the two regimes was observed to be close to the time needed for the transition from the Rouse mode to the reptation mode. The results showed that the content of the carbon black and the temperature affected the slope of the G*(t) – t curve. Scanning electron microscopy revealed the interface disappeared when the diffusion process was complete.     

A novel efficient medium for chromogenic catalysis of tetramethylbenzidine with horseradish peroxidase

The traditional surfactant sodium dodecyl sulfate (SDS) and ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF₄]) have been combined to create a novel efficient medium for chromogenic catalysis of 3,3',5,5'-tetramethylbenzidine with horseradish peroxidase in presence of H₂O₂. The results have shown the [Emim][BF₄] in the mediums can promote the rate of formation of the blue chromogen, the SDS is responsible for the stabilization of the blue chromogen due to the electrostatic attraction between positively charged blue chromogen and the negatively charged surfactant. The SDS/[Emim][BF₄] combination not only enhance catalytic activity of HRP remarkably but also stabilize the blue chromogen formed in the HRP oxidation of the substrate TMB compared to the conventional medium. Based on the superior combination of SDS and [Emim][BF₄], the colorimetric assay for detecting HRP activity and H₂O₂ concentration was established. This work demonstrates a novel efficient medium for chromogenic catalysis with potential applications in biosensors and clinical diagnosis.     

Synthesis of the melatonin receptor agonist Ramelteon using a tandem C–H activation–alkylation/Heck reaction and subsequent asymmetric Michael addition

An asymmetric synthesis of the melatonin receptor agonist Ramelteon 1 has been achieved, which involved a tandem C–H activation–alkylation/Heck reaction and subsequent highly diastereoselective asymmetric Michael addition to generate the corresponding chiral intermediate, which was readily converted into Ramelteon 1 in 19% overall yield in 15 linear steps.     

Hydrothermal synthesis and characterization of NiS flower-like architectures

Under the influence of thiocyanate anions (SCN^?) and cetyltrimethyl ammonium bromide (CTAB), NiS flower-like architectures were successfully synthesized by a one-step hydrothermal method. The synthesized flower-like architectures, with a multilayered and highly ordered texture, have diameters of several micrometers. X-ray powder diffraction (XRD) shows that the NiS flower-like architectures are rhombohedral crystalline. On the basis of condition-dependent experiments, the diffusion-limited aggregation (DLA) model and cage effect were used to explain the growth process of rhombohedral crystalline NiS flower-like architectures. Magnetic measurements showed that the coercivity (H_c) of the as-obtained NiS flower-like architectures was 102.14 Oe.     

Diffraction effects in planar wave-sphere interaction

Using the classical Mie scattering theory,we compute the energy density of an arbitrary partial wave(e.g.,the nth order) and then determine that the interaction between an incident planar wave and a sphere of radius a is the one between the sphere and those partial waves the order of which satisfies n≤ka.We also provide a simple expression to describe the diffracted wave in which the angle-dependent functions are employed.The difference between the accurate and the approximate expressions is demonstrated by numerical calculation.     

Preparation and photochromic properties of pyrazolones/polyvinyl alcohol composite films

Novel photochromic composite films have been successfully fabricated by dispersing pyrazolone derivative:1,3-Diphenyl-4-(3-chlorobenzal)-5-hydroxypyrazole 4-phenylsemicarbazone (1a) into hydrosol of polyvinyl alcohol (PVA). The microstructure, photochromic behaviors and thermal bleaching properties were investigated by Raman spectroscopy, X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and ultraviolet-visible absorption spectroscopy (UV-vis). The results showed that 1a was not only blended but also well dispersed in the PVA polymer films with a suitable content of chromophore. Upon UV light irradiation, the composite films gradually changed from colorless to yellow and recovered fully to the initial state upon thermal bleaching. The time constants of photochromic reactions were almost the same as those of 1a observed in their crystalline state, indicating that the photochromic phenomenon is barely disturbed by the polymer matrix.     

Effect of drying periods on antimony-doped tin dioxide-coated titanium electrode

The present work investigated the drying period effect on the activity, morphology, crystallinity, and other properties of antimony-doped tin dioxide-coated titanium electrodes prepared by coating pyrolysis method. The drying period is found to be an important factor affecting the electrode activity. The antimony content in the electrode decreased when the drying period increased. Simultaneously, crack width, Sn3d_5/2 binding energy, crystallite size, catalyst loading, and resistivity increased with the drying time. The results showed that the electrode prepared with the drying time of 10 min had the highest activity towards phenol degradation in the series under study.