SCR of NO over Ir/Al2O3 Catalysts. Importance of the Activation Procedure and Influence of the Dispersion

For SCR of NO the study of Ir/Al₂O₃ solids shows the importance of the activation procedure under mixtures containing CO (NO–C₃H₆–CO–O₂ or NO–CO–O₂). The selective reductant remains C₃H₆, however. The activation goes with an iridium particles sintering without Ir loss.     

Synthesis and characterization of Ag nanoparticles embedded in PVA via UV-photoreduction technique for synthesis of Prussian blue pigment

Silver nanoparticles doped in polyvinyl alcohol (AgNps/PVA) were synthesized via polymer-promoted reductive reaction of AgNO₃ and PVA under time-dependent exposure to UV radiation. The AgNps/PVA composites were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction, UV–Vis spectroscopy, and transmission electron microscopy to describe the structure, nuclearity, and distribution of Ag Nps within the PVA matrix. The UV–Vis spectrum of AgNps/PVA exhibited a broad surface plasmon absorption around 425–443 nm which originated from the formation of Ag NPs. Surface analysis by XPS indicated that the Ag NPs were grown solely on the PVA surface at UV exposure time of 2 h (2.0AgNPs/PVA). Increasing the UV exposure time to 4 h will cause the transformation of metallic nanosilver to oxidized nanosilver. UV–Vis absorption spectra were in situ recorded to follow the synthesis of Prussian blue (PB) on 2.0AgNPs/PVA (PB@2.0AgNPs/PVA). The colloidal dispersion of 2.0AgNPs/PVA in an acidic medium containing free Fe(III) ions and potassium hexacyanoferrate(III) revealed an additional band centered at 720 nm due to the intermetal charge-transfer absorbance of the polymeric Fe(II)-C-N-Fe(III) of the PB@2.0AgNPs/PVA nanocomposite. Control experiments were shown to involve a spontaneous electron transfer reaction between 2.0AgNPs/PVA and Fe(III) ions, with a concomitant decomposition of hexacyanoferrate(III) and formation of PB was observed. Moreover, IR gave clear cut evidence for the synthesis of PB@2.0AgNPs/PVA from the appearance of a band for the cyano group at 2090 cm^?1.     

In vivo study of hybrid biomaterial scaffold bioactive glass–chitosan after incorporation of Ciprofloxacin

The present study aimed to evaluate the effect of bioactive glass as well as the presence of Ciprofloxacin drug (%Cip) into bioactive glass–chitosan composite on the in vivo behavior of these scaffolds. These scaffolds were implanted in the femoral condyl of an ovariectomized rat. The serum and organs (liver and kidney) of the under investigated rats were analyzed. Also the physicochemical properties of the prepared implants were assessed using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) before and after implantation (at different periods of implantation). Biochemical and histological analyses of the under investigated rats proved the biocompatibility of the prepared scaffolds. The hydroxyapatite like layer was significantly precipitated on the surface of BG–CH scaffold than BG–CH–20Cip. In this same period, FT-IR of BG–CH shows complete disappearance of Si–O–Si. Their characteristics bands were replaced by P–O group arisen form bone apatite bands. Physicochemical results show progressive degradation of BG–CH and BG–CH–20Cip that occurred at the same time as replacement of the implant by an apatite layer. However, the bioresorbability and bioactivity of BG–CH are faster than those of BG–CH–20Cip. Therefore, the incorporation of the Ciprofloxacin in the BG–CH induces a retarding effect on the formation of the hydroxyapatite, and consequently on the ossification, without any side effects on the liver–kidney.     

Chemical Synthesis and Characterization of Novel Antibacterial Polycyclic Polymer

Polyaniline (PAn) and poly(alkyl substituted anilines) were synthesized in aqueous media by chemical polymerization of alkyl substituted aniline in presence of ammonium peroxydisulphate as an oxidant. The products were investigated in terms of morphology, chemical structure, and mechanism of polymerization with scanning electron microscope (SEM), transmission electron microscopy (TEM), fourier transform infrared (FTIR), and UV–visible spectroscopy (UV–vis), respectively. Results indicated that physicochemical properties of poly(alkyl substituted anilines) depend on substituent groups bonded to N-position. In general, alkyl-substituted PAn have similar chemical and optical properties to parent PAn and it seems that the substituted PAn follow the same polymerization mechanism as reported for PAn. The prepared polymers were then tested for the antibacterial properties against Gram-negative bacteria: Escherichia coli (E. coli). The antibacterial properties were assessed by measuring the zones of inhibition. The antimicrobial results showed clearly that PAn and poly(alkyl substituted anilines) exhibited excellent antibacterial activity against the growth of E. coli microorganism.     

Chemistry of Substituted Quinolinones IV. Regioselective Nucleophilic Substitution of 1,3-Dichlorobenzo[f]quinoline

1,3-Dichlorobenzo[f]quinoline 2 was obtained from 1-hydroxybenzo[f]quinolin-3-one 1. Nucleophilic substitution, hydrolysis, hydrazinolysis and azidation reactions of compound 2 have been studied and found regioselective. Also, 1-aminobenzo[f]quinolinone 11 was obtained and used to prepare the benzoquinolinylthiourea derivative 12, naphthonaphthyridinedione 13, benzoquinolinylhydrazonoquinoline 15 and benzo[f]-quinolinyl enamine 17.     

Hydrodynamics and mass transfer study of aliphatic alcohols in airlift reactors

Gas holdup and gas–liquid mass transfer coefficient were considered in an external airlift reactor. Air was sparged through some aliphatic alcohols (methanol, ethanol, n-propanol, and n-butanol) with different concentrations (0–1%, v/v). It was observed that gas holdup and mass transfer coefficient increased with increasing the number of carbons in alcohols. Furthermore, an increment in alcohols concentration increased gas holdup and mass transfer coefficient. The same behavior was observed in external and internal loop airlift reactors although gas holdup and mass transfer coefficient values were less than those of internal airlift reactor. According to the experiments, two correlations for gas holdup and mass transfer were developed.     

Bubble columns for condensation at high concentrations of noncondensable gas: Heat‐transfer model and experiments

Carrier gas based thermodynamic cycles are common in water desalination applications. These cycles often require condensation of water vapor out of the carrier gas stream. As the carrier gas is most likely a noncondensable gas present in very high concentrations (60–95%), a large additional resistance to heat transfer is present. It is proposed to reduce the aforementioned thermal resistance by condensing the vapor–gas mixture in a column of cold liquid rather than on a cold surface using a bubble column heat exchanger. A theoretical predictive model for estimating the heat‐transfer rates and new experimental data to validate this model are described. The model is purely physics based without the need for any adjustable parameters, and it is shown to predict heat rates within 0 to ?20% of the experimental values. The experiments demonstrate that heat‐transfer rates in the proposed device are up to an order magnitude higher than those achieved in existing state‐of‐the‐art dehumidifiers. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1780–1790, 2013     

Development of a model for dimethyl ether non-adiabatic reactors to improve methanol conversion

The modeling of adiabatic and non-adiabatic reactors, using three cooling mediums in the shell side of a shell and tube reactor in cocurrent and countercurrent flow regimes has been conducted. The cooling mediums used in this research are saturated water and methanol feed gas to a reactor which is preheated in the shell side and a special type of oil. The results of adiabatic reactor modeling show good compatibility with the data received from a commercial plant. The results of non-adiabatic reactor modeling showed that more methanol conversion can be achieved in a lower length of reactor, even though in some cases the maximum temperature in the tube side of the reactor is more than the deactivation temperature of the catalyst.     

Electrooxidation of alcohols at a nickel oxide/multi-walled carbon nanotube-modified glassy carbon electrode

Electrocatalytic oxidation of methanol and some other primary alcohols on a glassy carbon electrode modified with multi-walled carbon nanotubes and nano-sized nickel oxide (GCE/MWNT/NiO) was investigated by cyclic voltammetry and chronoamperometry in alkaline medium. The results were compared with those obtained on a nickel oxide-modified glassy carbon electrode (GCE/NiO). Both the electrodes were conditioned by potential cycling in the range of 0.1–0.6 V versus Ag/AgCl in a 0.10 M NaOH solution. The effects of various parameters such as scan rate, alcohol concentration, thickness of NiO film, and real surface area of the modified electrodes were also investigated and compared. It was found that the GCE/MWNT/NiO-modified electrode possesses an improved electrochemical behavior over the GC/NiO-modified electrode for methanol oxidation.     

Chitosan effects on glass matrices evaluated by biomaterial. MAS-NMR and biological investigations

Bioactive glass 46S6 and biodegradable therapeutic polymer (Chitosan: CH) have been elaborated to form 46S6-CH composite by freeze-drying process. The kinetics of chemical reactivity and bioactivity at the surface were investigated by using physicochemical techniques, particularly solid-state MAS-NMR. Immortalized cell line used to construct multicellular spheroids was employed as three-dimensional (3D) cell cultures for in vitro studies. Obtained results showed a novel structure of the composite; the chemical treatment (ultrasound, magnetic stirring, freeze drying process and lyophilization) led the bioactive glass particles to be loaded in the chitosan-based materials. ²⁹Si and ³¹P MAS-NMR results showed the emergence of two new species, Q _Si ³ (OH) and Q _Si ⁴ , which are characteristic of the vitreous network dissolution in simulated body fluid (SBF). MAS-NMR also confirmed the formation of amorphous calcium phosphate (ACP) at the surface of the initial 46S6-CH. Three-dimensional (3D) cell cultures highlighted the effect of chitosan, where the cell viability reached up to 78% in 46S6-CH composite and up to 67% in 46S6. The association of (CH) and bioactive glass (BG) matrix promotes a highly significant bioactivity, demonstrating surface bone formation and satisfactory behavior in biological environment.