Conversion of a green light emitting zinc-quinolate complex thin film to a stable and highly packed blue emitter film

Tris-(8-hydroxyquinoline) metal complex Znq₂, used as light-emitting layer in electroluminescent (EL) devices was synthesized and optical properties of as-deposited Znq₂ in thin films were studied. Interesting phenomenon was observed while studying the ageing and degradation behavior of Znq₂ films and consequently a stable form having strong blue photoluminescence (peak 465 nm) was discovered. This converted (from green to blue emitting) film has higher molecular packing density and comparable photoluminescence intensity with Znq₂ film. Here, we report on the production of this blue material under controlled conditions and its optical properties.The thin films have been deposited by thermal evaporation on quartz and silicon substrates. The optical constants (n and k) of green Znq₂ film and converted (to blue) thin films have been determined using spectroscopic ellipsometry. Environment induced effects on optical properties of films have been studied using ellipsometry, photoluminescence and UV–vis transmission measurements.     

Determination of Heat Transfer During Gear Blank Quenching

This article presents experimental and numerical results for the quench of a gear blank in agitated and stagnant oil. The time history of temperature is determined with a whole-domain optimizer technique inverse solution method. This article offers a procedure to calculate the surface heat transfer on the quenched part by utilizing a straightforward minimization of an appropriate norm. The article presents 10 variations in setting up this inverse problem. The results indicate that dividing the boundary of the gear blank into four zones and assigning a fixed heat transfer coefficient or heat flux to each zone yields an average error of 40 K. This error can be reduced by either increasing the number of zones or by allowing the heat transfer coefficient or heat flux to vary within the zones. Of these possibilities, variation of heat transfer within the zones results in a greater reduction of the average error for the required level of computational effort.     

Flame synthesis of carbon nano onions using liquefied petroleum gas without catalyst

Densely agglomerated, high specific surface area carbon nano onions with diameter of 30–40 nm have been synthesized. Liquefied petroleum gas and air mixtures produced carbon nano onions in diffusion flames without catalyst. The optimized oxidant to fuel ratio which produces carbon nano onions has been found to be 0.1 slpm/slpm. The experiment yielded 70% pure carbon nano onions with a rate of 5 g/h. X-ray diffraction, high-resolution electron microscopy and Raman spectrum reveal the densely packed sp² hybridized carbon with (002) semi-crystalline hexagonal graphite reflection. The carbon nano onions are thermally stable up to 600 °C.     

REGENERATION PROTOCOLS FOR FIXED BED REACTORS DEACTIVATED BY COKE

Coked catalyst in fixed bed reactors is regenerated by passing hot air mixed with a non-reacting diluent (like steam(. The concentration of oxygen in the regenerating stream is increased from the beginning of the regeneration following a so called regeneration protocol, in order to minimize the regeneration time but still maintaining the maximum temperature within the reactor below permissible level. In this paper, we have modelled the low temperature regeneration in fixed bed reactors and have suggested general regeneration protocols, suitable for wide range of process conditions

A pseudo-homogeneous model is developed to simulate regeneration of fixed bed reactors. The model accounts for major industrially important issues like, non-uniform coke deposition along the reactor length, hydrogen content (with faster burning of hydrogen) of coke and incomplete combustion of coke. Detailed qualitative understanding of the regeneration process and the role of protocol is developed. Specific guidelines were evolved and discussed to aid process engineers to select better regeneration protocol. One worked example of regeneration of fixed bed reactors is included     

Antibacterial Activity of Essential Oil and Extracts of <Emphasis Type="Italic">Cleistocalyx operculatus</Emphasis> Buds Against the Bacteria of <Emphasis Type="Italic">Xanthomonas</Emphasis> spp.

This study was undertaken to assess the antibacterial efficacy of the essential oil and extracts of Cleistocalyx operculatus buds against plant pathogenic bacteria of Xanthomonas spp. The diameter of inhibition zones of oil (1,000 μg/disc) and extracts (1,500 μg/disc) against the tested bacteria were found in the range of 7–23 mm. The MIC and MBC values of the oil and extracts against the tested Xanthomonas spp. ranged from 31.25–125 to 62.5–250 μg/ml and 125–500 and 250–1,000 μg/ml, respectively. The cell viability study demonstrated a potential detrimental effect of the oil (1,000 μg/ml) and hexane extract (250 μg/ml) on the tested Xanthomonas spp. Also the oil displayed significant antibacterial effects in vivo against Xoo KX019 and Xsp SK12 conducted on greenhouse-grown oriental melon plants (Cucumis melo L. var. makuwa). The results of this study suggest that C. operculatus-derived essential oil and extracts could be used as natural bactericides in the food and agriculture industries.     

Flow and heat transfer in serpentine channels

Serpentine channels are often used in microchannel reactors and heat exchangers. These channels offer better mixing, higher heat and mass‐transfer coefficients than straight channels. In the present work, flow and heat transfer experiments were carried out with a serpentine channel plate comprising of 10 units (single unit dimensions: 1 × 1.5 mm² in cross section, length 46.28 mm, D_h 1.2 mm) in series. Pressure drop and heat‐transfer coefficients were experimentally measured. Flow and heat transfer in the experimental set‐up were simulated using computational fluid dynamics (CFD) models to understand the mechanisms responsible for performance enhancement. The CFD methodology, thus, developed was applied to understand the effect of various geometrical parameters on heat transfer enhancement. A criterion was defined for evaluation of heat transfer performance (heat transfer per unit pumping power), thus, ensuring due considerations to required pumping power. The effect of geometrical parameters and the corresponding mechanisms contributing for enhancement are discussed briefly. Based on the results, a design map comprising different serpentine channels showing heat transfer enhancement with pumping power was developed for Reynolds number of 200 which will be useful for further work on flow and heat transfer in serpentine channels. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1814–1827, 2013     

Nano cobalt oxides for photocatalytic hydrogen production

Nano structured metal oxides including TiO_2, Co₃O₄ and Fe₃O₄ have been synthesized and evaluated for their photocatalytic activity for hydrogen generation. The photocatalytic activity of nano cobalt oxide was then compared with two other nano structured metal oxides namely TiO₂ and Fe₃O₄. The synthesized nano cobalt oxide was characterized thoroughly with respect to EDX and TEM. The yield of hydrogen was observed to be 900, 2000 and 8275 μmol h⁻¹ g⁻¹ of photocatalyst for TiO₂, Co₃O₄ and Fe₃O₄ respectively under visible light. It was observed that the hydrogen yield in case of nano cobalt oxide was more than twice to that of TiO₂ and the hydrogen yield of nano Fe₃O₄ was nearly four times as compared to nano Co₃O₄. The influence of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail.     

Glycerol Improves Skin Lesion Development in the Imiquimod Mouse Model of Psoriasis: Experimental Confirmation of Anecdotal Reports from Patients with Psoriasis

Glycerol is used in many skin care products because it improves skin function. Anecdotal reports by patients on the National Psoriasis Foundation website also suggest that glycerol may be helpful for the treatment of psoriasis, although to date no experimental data confirm this idea. Glycerol entry into epidermal keratinocytes is facilitated by aquaglyceroporins like aquaporin-3 (AQP3), and its conversion to phosphatidylglycerol, a lipid messenger that promotes keratinocyte differentiation, requires the lipid-metabolizing enzyme phospholipase-D2 (PLD2). To evaluate whether glycerol inhibits inflammation and psoriasiform lesion development in the imiquimod (IMQ)-induced mouse model of psoriasis, glycerol’s effect on psoriasiform skin lesions was determined in IMQ-treated wild-type and PLD2 knockout mice, with glycerol provided either in drinking water or applied topically. Psoriasis area and severity index, ear thickness and ear biopsy weight, epidermal thickness, and inflammatory markers were quantified. Topical and oral glycerol ameliorated psoriasiform lesion development in wild-type mice. Topical glycerol appeared to act as an emollient to induce beneficial effects, since even in PLD2 knockout mice topical glycerol application improved skin lesions. In contrast, the beneficial effects of oral glycerol required PLD2, with no improvement in psoriasiform lesions observed in PLD2 knockout mice. Our findings suggest that the ability of oral glycerol to improve psoriasiform lesions requires its PLD2-mediated conversion to phosphatidylglycerol, consistent with our previous report that phosphatidylglycerol itself improves psoriasiform lesions in this model. Our data also support anecdotal evidence that glycerol can ameliorate psoriasis symptoms and therefore might be a useful therapy alone or in conjunction with other treatments.     

Dielectric properties of nylon 6/clay nanocomposites from on-line process monitoring and off-line measurements

Nylon 6/clay nanocomposites were studied by dielectric relaxation spectroscopy (DRS) to correlate morphology and microstructure with relaxation behavior of the polymer matrix at the molecular level. Partially exfoliated clay microstructure was achieved by extruding nylon 6 with surfactant-treated montmorillonite clays. A new on-line dielectric slit die sensor was used to examine the melt state properties during extrusion compounding. Solid state properties were probed by off-line DRS over a temperature range from −50 to 180 °C in a frequency range from 10⁻³ to 10⁶ Hz. Using non-linear regression methods in conjunction with the temperature-frequency positions of relaxations observed in the dielectric loss data, the experimental data were fit with the Havriliak-Negami and Cole-Cole dielectric relaxation functions corrected for electrode polarization and DC conductivity. Characteristic frequency, relaxation strength, and DC conductivities were extracted from curves with overlapping relaxation modes. Two dielectric relaxations were observed in the composite melt: the α relaxation associated with molecular segmental motion, and a Maxwell-Wagner relaxation (MW) resulting from interfacial polarization at the resin/clay interface. Analysis of the solid-state data yielded a comprehensive master plot of dielectric relaxations attributed to segmental and local molecular dynamics and other relaxations resulting from water and Maxwell-Wagner interfacial polarization. The impact of clay fillers is seen in nearly all relaxation processes changing both characteristic frequency and strength of the relaxation.     

Fabrication of high pressure hydrogen adsorption/desorption unit—Adsorption study on flame synthesized carbon nanofibers

An in-house custom made high pressure adsorption/desorption unit has been designed and fabricated to study reversible hydrogen (H₂) intake capacity, hysteresis, kinetics, plateau pressure of various nanomaterials, zeolites and metallic compounds, in the pressure range of 1 ≤ P ≤ 150 atm. The unit has been used to estimate H₂ intake capacity of carbon nanofibers prepared by flame synthesis in the absence of catalyst. H₂ adsorption studies have been carried out in the pressure range of 25–100 atm at 297 K. The maximum H₂ intake capacity has been observed to be 3.7 wt% at 100 atm.