Physicochemical properties of precursors of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZrO<Subscript>2</Subscript> oxide ceramics prepared by electrochemical method

Scanning electron microscopy, X-ray, and thermal analysis are used to examine the structure and properties of dispersive systems based on aluminum and zirconium oxides prepared electrochemically. The effect the conditions of synthesis have on the structure and morphology of Al₂O₃–ZrO₂ particles is studied. It is shown that the effect of an electric field on the reaction medium allows us to adjust the physicоchemical properties and morphology.     

Synthesis and properties of novel reusable nano-ordered KIT-5-<Emphasis Type="Italic">N</Emphasis>-sulfamic acid as a heterogeneous catalyst for solvent-free synthesis of 2,4,5-triaryl-1 <Emphasis Type="Italic">H</Emphasis>-imidazoles

A novel silica-bonded propyl-N-sulfamic acid nanocatalyst (NHSO₃H-KIT-5) supported on modified silica mesopore KIT-5 as an organic-inorganic hybrid with high specific surface area was successfully prepared. The 3-aminopropyltriethoxysilane (APTES) on KIT-5 was reacted with chlorosulfonic acid and accurately characterized by the FT-IR, XRD, SEM, EDAXS, and TGA techniques. This heterogeneous and recyclable catalyst catalyzed one pot, multicomponent condensation of benzil, aromatic aldehydes, and ammonium acetate in the presences of 0.05 g of nanocatalyst under solvent-free conditions to afford triaryl-imidazoles in excellent yields. This catalyst showed high catalytic activity under green conditions. This reaction was performed under open air conditions and required no special reaction conditions or chromatographic separation for purification.     

Synthesis of 1,3,4-oxadiazoles from the reaction of N-isocyaniminotriphenylphosphorane (NICITPP) with cyclohexanone,a primary amine and an aromatic carboxylic acid via intramolecular aza-Wittig reaction of in situ generated iminophosphoranes

The 1:1 imine intermediate generated by the addition of a primary amine to cyclohexanone trapped by N-isocyaniminotriphenylphosphorane (NICITPP) in the presence of aromatic carboxylic acids and the corresponding iminophosphorane intermediate was formed. Disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were completed in neutral conditions at room temperature (18-26°C). The disubstituted 1,3,4-oxadiazole derivatives were produced in excellent yields.     

On mechanics of saturated granular materials

A continuum theory of saturated granular materials is formulated. The basic balance laws for the solid phase as well as for the fluid phase are presented. The constitutive equations are derived and the basic equations of motion of the solid and fluid continua are obtained. Several cases of interest, such as incompressible granules saturated with liquids are discussed. It is shown that the theory contains, as its special cases, the Mohr-Coulomb criterion for a granular material as well as Darcy's law of flow through porous media.     

Gas-particle two-phase turbulent flow in a vertical duct

Two-phase gas-phase turbulent flows at various loadings between the two vertical parallel plates are analyzed. A thermodynamically consistent turbulent two-phase flow model that accounts for the phase fluctuation energy transport and interaction is used. The governing equation of the gas-phase is upgraded to a two-equation low Reynolds number turbulence closure model that can be integrated directly to the wall. A no-slip boundary condition for the gas-phase and slip-boundary condition for the particulate phase are used. The computational model is first applied to dilute gas-particle turbulent flow between two parallel vertical walls. The predicted mean velocity and turbulence intensity profiles are compared with the experimental data of Tsuji et al. (1984) for vertical pipe flows, and good agreement is observed. Examples of additional flow properties such as the phasic fluctuation energy, phasic fluctuation energy production and dissipation, as well as interaction momentum and energy supply terms are also presented and discussed.

Applications to the relatively dense gas-particle turbulent flows in a vertical channel are also studied. The model predictions are compared with the experimental data of Miller & Gidaspow and reasonable agreement is observed. It is shown that flow behavior is strongly affected by the phasic fluctuation energy, and the momentum and energy transfer between the particulate and the fluid constituents.     

Solid Phase Micro-extraction – Gas Chromatography–Mass Spectrometry to Characterize Pyrolysis Products from Textiles

Headspace solid phase micro-extraction gas chromatography–mass spectrometry (HS-SPME GC–MS) was used for identifying thermally labile volatile compounds from cotton, wool, polyester, olefin, silk, and acrylic. Volatile compounds were generated from the textiles using a pyrolysis apparatus prior to GC–MS. Pyrolysis temperatures ranged from 190 to 550°C. Each textile displayed a unique chromatogram containing compounds that were consistent with the chemical structure of the textile. Experimental parameters that were investigated included the temperature, sample size, and sampling time to determine their effect on the number and intensity of peaks in the chromatograms as well as to identify optimum conditions for analysis. Heating of each sample was achieved using a resistively heated Pt wire. Full pyrolysis at 550°C of the textiles appeared to give the best results in terms of peak height relative to background. A range of sample sizes (0.02–1.5?mg) were used and, generally, ≤0.02?mg was used for identifying the textiles. The reproducibility of retention times for selected compounds in the chromatograms was less than 1% relative standard deviation. The combination with mass spectrometry provided valuable structural information.     

Miniature Neutron Source Reactors in medical research: achievements and challenges

Miniature neutron source reactors (MNSRs) and their challenges were investigated. Then, MNSRs structure and operation were discussed, and conflicting usages of high enriched uranium fuel and its technical challenges were explored. By using low enriched uranium it is possible to produce ⁹⁹Mo isotopes with similar quality, plus using low enriched uranium does not increase the potential risks and high does level. Furthermore, it is possible to produce several medical radioisotopes such as ⁹⁹Mo/^{99 m}Tc generator, ¹³¹I, ⁶⁵Zn, and ¹⁷⁷Lu. These reactors can be employed in Boron Neutron Capture Therapy. After conversion, these reactors can be used more frequently and effectively.     

Per-2,3-O-alkylated β-cyclodextrin duplexes connected with disulfide bonds

Per-2,3-di-O-methyl- and per-2,3-di-O-allyl-β-cyclodextrin duplexes held by two disulfide bonds between their primary faces have been prepared. Permethylation significantly increased the solubility of the cyclodextrin duplexes in a wide range of solvents from water to chlorinated hydrocarbons. Per-2,3-di-O-methylated duplexes are able to form inclusion complexes with organic molecules in aqueous solutions, yet the stability constants are lower by 4–5 orders of magnitude as compared to analogous non-alkylated β-cyclodextrin duplexes.