Influence of Carbon on SOx Emissions from Glass Processing

Carbon reacts with Na₂SO₄ in glass batches, influencing SO _x emissions. To study the role of carbon active surface area (ASA) in the decomposition phenomena, Na₂SO₄ is reacted with three carbons with a wide ASA range. The decomposition behavior was evaluated by thermogravimetric analysis (TGA) and evolved gas analysis via mass spectrometry and Fourier transform infrared spectrometry. Higher carbon ASA yields lower decomposition temperatures. SO _x emissions are realized at temperatures as low as 773 K. Isothermal Na₂SO₄–C decomposition initiates via the nucleation of Na₂S. The rate constants for the nucleation regime are normalized against ASA, yielding an activation energy of 275 kJ/mol for nucleation.     

The reaction of 1,2-dichloroethane with copper

The decomposition of 1,2-dichloroethane on polycrystalline copper has been studied using a microreactor. The reaction is found to have an activation energy of 81±5 kJ mol^–1 generating gaseous ethene and chemisorbed chlorine. The reaction terminates on completion of a monolayer of chemisorbed chlorine and is followed by a much slower reaction. The rate limiting step is thought to be C₂H₄Cl_2(phys)C2H₄Cl(_ads)+Cl_ads The reaction is compared with a UHV study of the same molecule on Cu(l 11) and the possibility of a negative ion transition state is discussed.     

Thermal decomposition behavior of poly[3,3-bis(ethoxymethyl) oxetane] and related polyethers

The thermal decomposition behavior of poly[3,3-bis(ethoxymethyl)oxetane] (polyBEMO) was examined and compared to the decomposition of poly(ethylene oxide) (PEO) and poly(tetramethylene oxide) (polyTHF). Differential scanning calorimetric (DSC) studies as a function of heating rates and at constant temperature as a function of time yielded activation energies of 45–50 kcal/mol, characteristic of polyether decomposition. First-order decomposition kinetics were found. The reaction is endothermic, with a heat of decomposition of 18.6 kcal/mol. Effusion mass spectroscopy on polyBEMO showed major peaks at 112, 140, 168, and 174 amu. A mechanism is proposed in which the thermal scission of the ether bonds in both the polymer chain and in the appendanges initiates the decomposition. The main decomposition reaction for polyBEMO can be written as where the appendages and main chain are cleaved in an unknown order.     

An analysis of moving-bed flow of solids down standpipes and side valves

A method of analysing solids downflow through standpipe and slide valve in the moving bed mode is presented. The method is based on combining Yoon and Kunii equations for moving-bed flow with a proposed modified orifice equation for gas—solid flow. The analysis correctly predicts the observed trend of the effects of gas injection into the standpipe. It also provides quantitative prediction of the conditions for transition from moving-bed flow to dense phase fluidized solids flow and to lean phase “streaming flow”. The latter flow pattern refers to solids streaming down a tube at high voidage typified by the discharge of solid down a tube with no constriction at the lower end of the tube. Further work is required to test the general applicability of the present analysis and to extend the analysis to yield a generalized quantitative flow regime diagram for downflow of solids in a pipe.     

Feeding deterrency of some pyrrolizidine,indolizidine, and quinolizidine alkaloids towards pea aphid (Acyrthosiphon pisum) and evidence for phloem transport of indolizidine alkaloid swainsonine

Journal of Chemical Ecology - The feeding deterrency of a series of pyrrolizidine, indolizidine, and quinolizidine alkaloids and selected derivatives was measured against the pea aphid...     

A generalist herbivore in a specialist mode Metabolic,sequestrative, and defensive consequences

Adults of a generalist herbivore, the lubber grasshopper,Romalea guttata, can be converted to functional specialists by feeding them exclusively on catnip,Nepeta cataria. No obvious adverse effects on adult development resulted from this enforced monophagy. Notwithstanding the fact thatR. guttata has had no coevolutionary relationship with this Eurasian mint, it readily sequesters compounds that are identical to or derived from the terpenoid lactones that are characteristic ofN. cataria. R. guttata appears to both biomagnify minor allelochemicals and to sequester metabolites of theNepeta terpenes in its paired defensive glands. The levels of autogenously produced phenolics are not affected by feeding onN. cataria and the defensive secretions of catnip-fed grasshoppers are more repellent to ants than those of wild-fed acridids. Metabolites of theN. cataria monoterpenes are sequestered in the defensive glands when catnip is added to the natural diet ofR. guttata. The ability of a generalist,R. guttata, to facilely bioaccumulate a potpourri of foreign allelochemicals when feeding in a specialist mode is analyzed in terms of its biochemical, physiological, and functional significance. Sequestration is examined as a response to the enteric effronteries represented by the phytochemicals that can be characteristic of the overload in a monophagous diet.     

First Identification of a Putative Sex Pheromone in a Praying Mantid

Praying mantids are models for a wide variety of behavioral, physiological, and ecological studies, and sex pheromones have been assumed to be important components of their biology. However, no mantid pheromone has ever been identified. We collected volatiles emitted by females of the mantid, Sphodromantis lineola, via solid phase microextraction (SPME). Mass spectral analysis revealed the collected volatiles to be a mixture of pentadecanal and tetradecanal. We prepared a synthetic mixture of these compounds, and found that males were both attracted to this mixture and stimulated to exhibit typical precopulatory behavior. We then examined male antennae with scanning electron microscopy, and confirmed the presence of porous antennal sensilla typical of insect pheromone receptors, i.e., that male mantids are equipped with the appropriate morphological apparatus to receive volatile chemical signals. Pheromones, in conjunction with visual and tactile cues, are thus an important feature of the reproductive biology of this, and undoubtedly other species of mantids. In addition to adding a crucial aspect of behavioral biology to our knowledge of this group, identification and synthesis of mantid pheromones may be a first step in attracting and aggregating these generalist predators for use in pest control.     

Highly Transparent Lu-α-SiAlON

Novel Lu-α-SiAlON ceramics were produced by hot pressing mixtures of Si₃N₄, Lu₂O₃, AlN, and Al₂O₃ at 1950°C for 2 h in a nitrogen atmosphere. The resultant SiAlON was fully dense and possessed a uniform, equiaxed microstructure with a grain size of ∼1 μm, which resulted in a high hardness of >19 GPa. In addition to high hardness, the sample showed very high optical transparency in the visible light region, with >70% transmission at higher wavelengths. This high transparency was attributed to the uniform, dense microstructure and lack of residual grain-boundary phase.     

Recent studies of self-condensation and co-condensation of melamine-formaldehyde resins; cure at low temperatures

Self-condensation: recent research on the chemical pathways by which alcoholated melamine-formaldehyde (MF) resins react with themselves and on the product structures is summarized. Model compound studies suggest that bridges are less stable than widely thought unless they are in hexahydro-1,3,5-triazine ring structures. In acyclic structures they are probably less stable than bridges. Co-condensation: studies of how the composition of MF resins influences the rates of reaction with poly(ol) co-reactant show that MF resins that contain very low levels of and/or functionality are quite reactive. Reactivities of a variety of poly(ester) and acrylic coreactants were studied. By combining reactive MF resins with reactive co-reactants one can formulate high solids enamels that cure by co-condensation in 30 min at 50 to 65 °C with 0.5 parts per hundred (phr) of p-toluenesulfonic acid (p-TSA) catalyst. Cure at 25 °C appears feasible with higher catalyst levels.     

Occurrence of wax esters in the tissues of the organge roughy (Hoplostethus atlanticus)

The skin, skeleton and a fat-filled swim bladder of the orange roughy (Hoplostethus atlanticus) each contained greater than 20% lipid by wet weight which was almost entirely wax esters. These had carbon numbers of 34–40 consistent with the major fatty acid being 18∶1 and the major fatty alcohols being 16∶0, 18∶1, 20∶1 and 22∶1. In contrast, the liver and the roe contained appreciable quantities of glycerolipids with 18∶1 and 22∶6 as the major fatty acids.