Preparation of dendritic adamantane‐based polymers/layered silicate nanocomposites

An adamantane‐based atom transfer radical initiator (Adm‐Br) was prepared by the treatment of 1‐[[N‐[2‐Hydroxy‐l,l‐bis(hydroxymethyl)ethyl]amino]carbonyl]adamantane with bromopropionyl bromide. The resulting initiator was subsequently used in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) to form (Adm‐p‐MMA), which was successfully used, as a macroinitiator, in further ATRP reactions with 3‐O‐methacryloyl‐1,2 5,6‐di‐O‐isopropylidene‐α‐d ‐glucofuranose (gly), a glycomonomer, to afford the Adm‐p‐MMA‐b‐gly polymer. The new Adm‐p‐MMA‐b‐gly polymer subsequently was employed to form a nanocomposite with chitosan‐modified, Nanofil clay (NC). The resulting Adm‐p‐MMA‐b‐gly/NC composite material was progressively hydrolyzed to regenerate the OH groups of the glucose units within the Adm‐p‐MMA‐b‐gly copolymer. The polymer/NC nanocomposites were characterized by X‐ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, and transmission electron microscopy. POLYM. ENG. SCI., 54:2669–2675, 2014. © 2013 Society of Plastics Engineers     

Characterization of cobalt oxide nanocatalysts prepared by microemulsion with different surfactants, reduction by hydrazine and mechanochemical method

Cobalt oxide (Co₃O₄) nanoparticles were prepared by different techniques (i) by microemulsion with different surfactants, (ii) by reduction as nanometal with hydrazine hydrates and (iii) by thermal treatment of precursor obtained from mechanochemical reaction of Co(NO₃)·H₂O with NH₄HCO₃. The products were calcined at 400 °C to give crystalline Co₃O₄. The obtained different samples of Co₃O₄ were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) from which the particle size was calculated. The results revealed that all samples obtained from different methods were nanosized particles.     

Influence of germination techniques on sprout yield,biosynthesis of ascorbic acid and cooking ability,in chickpea (Cicer arietinum L.)

Effects of germination time and illuminations on sprout yield, biosynthesis of ascorbic acid, cooking ability and moisture accumulation in chickpeas were significant (p ? 0.01). Green light had the highest promoting effect on the ascorbic acid level (40.59 mg/100 g) as compared to other illuminations but significantly reduced the sprout yield (188.6 g) as compared to dark, fluorescence and γ-rays illuminations with significantly high sprout yield (196 g) and imbibing moisture (51%). Cooking time was reduced by 43% due to γ-rays in un-soaked seed. Cooking time increased in all treated chickpea samples after 24 h germination and thereafter decreased significantly. Red light significantly increased the cooking time (68.44 min) followed by fluorescent (64.5 min), yellow (61.8 min) and green light (60.9 min). The results indicated that germination of chickpea under green light was an effective process in enhancing ascorbic acid content while dark, fluorescence and γ-rays were effective in promoting sprout growth and to some extent biosynthesis of ascorbic acid.     

Determination of Sensory Thresholds of Selected Calcium Salts and Formulation of Calcium-fortified Pocket-type Flat Bread

Pita bread loaves were prepared from flours fortified with calcium carbonate, calcium sulfate, and tricalcium dicitrate at 8 ascending levels to provide ranges of 800 to 2500, 700 to 1500, and 400 to 2000 mg of added Ca/100 g flour, respectively. The detection thresholds of calcium salts in pita bread were determined by the 3‐alter‐native forced choice (3‐AFC) test and construction of dose‐response curves. Detection thresholds determined by calculating geometric mean of individual best estimate thresholds, using criterion of 50%‐above‐chance and probit analysis of 3‐AFC data, were in the middle region of calcium concentrations. Analysis of dose‐response curves yielded values for thresholds outside the range of surveyed calcium concentrations. The detection threshold of CaSO₄ (2724 mg/100 g) in pita bread was significantly higher (P < 0.01) than those of calcium carbonate (1984 mg/100 g) and tricalcium dicitrate (2132 mg/100 g). Calcium‐fortified pita bread was similar (P < 0.01) to its regular counterpart when formulated to contain 1254.6, 1772.5, or 1155 mg/100 g of CaCO₃, CaSO₄, or tricalcium dicitrate, respectively. At the indicated levels of fortification, calcium‐fortified pita bread is expected to provide between 61% and 126.5% of the recommended daily intake for calcium for Middle Eastern populations.     

Channelled optical fibre photoreactor for improved air quality control

An optical fibre reactor with 30 hexagonal-shaped channels distributed within the optical fibre structure was investigated as a gas-phase photocatalytic reactor. TiO₂ photocatalyst, with SiO₂ sol acting as a binder, was coated on the channel walls at a thickness of 1.5 μm. Effective light propagation lengths of 3.4 and 4.9 cm were observed for incidental angles of 81.5° and 87.1°, respectively. The TiO₂-coated channelled optical fibre reactor (COFR) was assessed for the photocatalytic degradation of gas-phase ethylene. The photocatalytic reaction rate of ethylene degradation was linear with respect to the incident photons. The reaction rate order for the incident photons was determined to be 0.93. Despite a longer effective light propagation length for an incidental angle of 87.1°, the quantum yield was independent of the incidental angle. The independence of the quantum yield on the incident photons and the angle of light incidence was attributed to the COFR design, where the propagating light was wholly confined within the reactor and, in turn, more effectively utilised by the TiO₂.     

Parity generator and parity checker in the modified trinary number system using savart plate and spatial light modulator

The parity generators and the checkers are the most important circuits in communication systems. With the development of multi-valued logic (MVL), the proposed system with parity generators and checkers is the most required using the recently developed optoelectronic technology in the modified trinary number (MTN) system. This system also meets up the tremendous needs of speeds by exploiting the savart plates and spatial light modulators (SLM) in the optical tree architecture (OTA).     

3D-Supramolecular Coordination Polymers as Effective Oxidizing Agents Towards 2,4-Dichlorophenol and 2,6-Di-<Emphasis Type="Italic">t</Emphasis>-butylphenol

3D-supramolecular coordination polymers (SCP) of the type [(R₃Sn)₃Fe^III(CN)₆]; R = CH₃ (I), n-Butyl (II) and phenyl (III) contain wide expandable channels capable of encapsulating and in situ oxidizing 2,4-dichlorophenol (DClP) and 2,6-di-t-butylphenol (DBP) to 2-chloro-1,4-benzoquinone (2-ClBQ) and 3,5,3,5-tertra-t-butyl-4,4-diphenoquinone (BDPQ), respectively, to form new host–guest supramolecular coordination polymers (HGSCP) (1–6). The oxidation products are investigated by spectrophotometry and HPLC methods. A kinetic study indicated a first-order reaction with respect to the hosts SCP I–III. The mechanism and rate of oxidation are discussed in relation to the structure of the SCP.     

Tunable TiO2 (anatase and rutile) materials manufactured by mechanical means

Anatase and rutile are two naturally found titanium dioxide phases with attractive dielectric, catalytic, and photo-catalytic characteristics. Anatase and rutile are photo-catalytically active in the UV region, since their band gaps are 3.2 eV and 3.75 eV, respectively. In this work is proposed a cost-effective, easy to launch methodology for modification of the TiO₂ bandgap. Such modifications will make the oxides photo-catalytically active in a wider optical range from the visible wavelengths to an extended UV spectrum. The proposed methodology is based on mechanical means such as mixing and milling. Various ratios of anatase:rutile were investigated and milled from 0 (mixing only) to 50 h using high energy mills. The results on mixing and milling show that it is possible to modify the bandgap of the TiO₂ from 2.53 eV to 4.04 eV. The characterization was conducted by means of X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, and optical spectroscopy.