A water slurry method of extracting aflatoxin from peanuts

A water slurry method in which 1100 g of comminuted peanuts was blended with 1500 ml of tap water for 3 min in a blender and the aflatoxin in a 130-g portion of the water slurry was extracted by solvent according to methods similar to those used in Method II of AOAC was compared to the method presently used by the Food Safety and Quality Service, USDA. The proposed water slurry method requires only 180 and 60 ml per sample, respectively, of methanol and hexane compared to the 1650 and 1000 ml, respectively, required by the FSQS method. Blending comminuted peanuts with water reduced the average particle size and distributed the contaminated particles throughout the slurry. Ninety-four percent of the blended particles passed a sieve with 149-μ openings compared to only 66% of the unblended product. Variance among analyses with the FSQS method did not differ significantly from the variance among analyses with the slurry method. However, analyses with the slurry method averaged 16% more aflatoxin than with the FSQS method. Paper No. 6189 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC.     

Uncovering microstructure and composition susceptibility of high permittivity ceramic granules to plasma-induced arc breakdown

Effective diversion of surge currents is vital to prevent unwanted damage to sensitive electronics. Among the most successful and efficient strategies relies on a dielectric stimulated arc breakdown mechanism with high permittivity ceramic granules in a spark-gap geometry. Although generally regarded as a self-healing process, substantial energy deposition may occur that, over time, diminishes the ability to withstand repeated electrical assaults. We investigate the susceptibility of lead–magnesium–niobate–lead titanate (PMN–PT) granule microstructure and composition changes following many exposures to high voltage impulses resulting in arc breakdown. Scanning electron microscopy and energy-dispersive spectroscopy mapping reveal a broad range of thermal and mechanical defects entailing thermal reduction of constituent PMN–PT metal ions and recasting due to rapid eruption of volatile species. Additionally, evidence of local melting and microcracking are apparent that can have deleterious impact on the proper function of the granules, namely, the ability to concentrate electric fields across air gaps to establish and sustain discharge pathways. We propose that the localized nature of damage and stochasticity associated with the dielectric stimulated breakdown mechanism may allow granules to maintain functionality provided no permanent conduction paths are established.     

Principles of design for laminated tooling

The emergence of rapid prototyping over the last 7-8 years has had a revolutionary effect in many companies undertaking new product design. Currently, the emphasis has moved from rapid prototyping to rapid tooling. Use of laminated tooling for sheet metal working has already been proved and some work has also been undertaken to build laminated tooling for moulding plastics. Laminated tooling is relatively rare at the moment and as more tools are built using this technique the benefits and limitations will become more clear.     

Differential recognition of geometric isomers by the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae): Evidence for only three essential components in aggregation pheromone

For two decades, the aggregation pheromone of the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae), was thought to consist of four compounds: I [(+)-(Z)-2-isopropenyl-1-methylcyclobutane ethanol]; II [(Z)-3,3-dimethyl-^I,-cyclohexane ethanol]; III [(Z)-3,3-dimethyl-^1,-cyclohexane acetaldehyde); and IV [(E)-3,3-dimethyl-^1,-cyclohexane acetaldehyde). Evidence is presented from behavioral and electrophysiological studies to show that only three of these components, I, II, and IV, are essential for attraction. Competitive field tests, in which each possible three-component blend was tested against the four-component mixture, demonstrated that omission of I, II. or IV resulted in decreased trap captures (P < 0.01). Trap captures by these blends lacking I, II, or IV resembled those by the hexane solvent alone in a similar experiment. However, omission of III did not significantly alter field attractiveness of the blend. Dosage-response curves constructed from electroantennogram responses of both males and females to serial dilutions of III, IV, and a 5050 mixture of the geometric isomers III and IV showed both sexes to be 10- to 100-fold more sensitive to IV than III. Data from the electrophysiological studies were consistent with a single acceptor type for the (E)-cyclohexylidene aldehyde, IV, for males, and possibly one or two acceptor types for III and IV for females. Possible roles for the (Z)-cyclohexylidene aldehyde, III, and implications for the pheromonal attractant currently used in boll weevil eradication/suppression programs are discussed.     

Electroantennogram responses of mediterranean fruit fly,Ceratitis capitata (Diptera: Tephritidae) to trimedlure and itstrans isomers

Electroantennograms (EAGs) of unmated laboratory-reared male and femaleCeratitis capitata (Wiedemann) were recorded in response to the attractant trimedlure [tert-butyl 4(and 5)-chloro-trans-2-methylcyclohexane-1-carboxylate] and its fourtrans isomers. For both sexes, the magnitude of the EAG response was relatively low as compared to other previously tested compounds (i.e., plant volatiles). Dosage-response curves generated for all TML isomers revealed that flies responded to increasing dosages over a relatively narrow range (two to three log steps). Responses for both sexes peaked at ca. 10 μg dose for all isomers. Antennal response in males was greatest to the C isomer followed by the B₁, A, and B₂ isomers, while responses of females were greatest for the A isomer followed by B₁, C, and B₂. Both sexes exhibited a long recovery period for the response potential to return to baseline at doses above 1 μg for all of the isomers tested, except for B₂. The low EAG sensitivity to trimedlure and the apparent EAG selectivity to the C isomer in males are discussed in relation to the known field attractancy of males to the C, A, B₁, and B₂ isomers.