ALBERT

Notes: A new organic N-chloramine disinfectant (3-chloro-4, 4-dimethyl-2-oxazolidinone, agent I) has been compared with calcium hypochlorite as to its tendency to react with organic matter in water to produce toxic trihalomethanes. Agent I reacts much less readily with organic demand than does calcium hypochlorite. This study shows that agent I should be safe to use as a disinfectant for water containing appreciable organic load in either sunlight or darkness. On the other hand, calcium hypochlorite may not be a satisfactory disinfectant from the toxicity standpoint for water which contains organic load which must be stored for extended time periods in either sunlight or darkness.

Notes: Aspergillus flavus NRRL-6549 and NRRL-6550 were tested for their ability to produce aflatoxins, but only NRRL-6549 produced detectable amounts of B1. Summer sausages prepared and inoculated with NRRL-6549 were smoked and held at 10 or 30°C for 3 or 6 wk at low or high humidities. Mold growth occurred on both inoculated and uninoculated sausages, the amount increasing with time, temperature and humidity. Smoking delayed but did not prevent mold growth. At 3 wk, aflatoxins were detected only in unsmoked inoculated sausages held at 30°C and high relative humidity. After 6 wk, B1 was found only in unsmoked inoculated sausages held at 10°C and high humidity, but at 30°C was present at 2.6–6.6 μg/kg in all inoculated samples at both low and high humidities.

Notes: Dry cured bacon was made under carefully controlled processing conditions in a pilot plant study using α-tocopherol-coated salt as part of the dry cure. Approximately, a 96% reduction in N-nitrosopyrrolidine (NPYR) levels in the fried bacon was achieved with an ingoing α-tocopherol level of 500 mg/kg. NPYR levels in the cookout fat were reduced approximately 92% using the same level of α-tocopherol. Bacon, prepared by a small scale commercial operation, also contained reduced levels of NPYR when processed with α-tocopherol-coated salt, despite high levels (〉100 mg/kg) of residual sodium nitrite in the finished bacon. Results comparing effectiveness of α-tocopherol and mixed tocopherols as nitrosamine blocking agents were inconclusive. Although, α-tocopherol appeared to be more effective as a blocking agent (91% versus 73% inhibition of NPYR), the difference in percent inhibition achieved could possibly be attributed to apparently lower levels of residual mixed tocopherols in the finished bacon.

Notes: Chicken frankfurters, prepared with various levels of sodium nitrite (0, 20, 40, 60, 100, and 156 ppm) were heated either in a microwave oven, boiled or broiled and then analyzed for N-nitrosamines. As expected, “apparent” N-nitrosamine levels increased with increasing concentrations of sodium nitrite. The effect of the various heating procedures on N-nitrosamine formation was inconclusive, due possibly to the low levels of “apparent” N-nitrosamines present. The two most common N-nitrosamines present appeared to be N-nitrosodimethylamine and N-nitrosomorpholine. However, only in the frankfurter samples prepared with 156 ppm nitrite was the presence of N-nitrosomorpholine confirmed by mass spectrometry.

Notes: Abstract Exposure of workers applying paraquat to fields of tomatoes and citrus, and diquat to waterways containing water hyacinths and hydrilla, was monitored with dermal α-cellulose pads attached at each of ten body locations and with personal air monitors. Estimated total body exposure for tomato applicators was apparently influenced by tractor type. Exposure levels from highest to lowest were: open tractor 〉 enclosed cab tractor ⩾ high-clearance tractor. Citrus applicators' exposure to paraquat averaged 28.5 mg/hr and 12.2 mg/hr, with tank concentrations of 0.11% and 0.07%, respectively. Diquat applicators received minimal exposure. Respiratory exposure was 〈0.1% of the total body exposure in all experiments. Urine samples collected periodically for all workers were, with one exception, without detectable pesticide contamination. Use of disposable coveralls and regularly washed impermeable gloves should effectively reduce exposure.

Notes: Abstract The physical properties, chemical composition and structure of a carbonaceous deposit formed on a radiantly heated HK40 steel tube at 920 to 930° C after ~ 50 days cracking operations in naphtha-steam have been examined. The deposit consisted of two layers. The innermost (i.e. adjacent to the tube) varied in thickness from 20μm to 1.5 mm, and was formed by heterogeneous reactions catalysed by iron and nickel. Enhanced deposition was characterized by a higher concentration of entrapped chromium rich oxide particles, a principal source of catalytic species. The outer deposit layer was of uniform thickness, had a columnar radial and an axial layered structure, which together with the absence of any significant inorganic constituents, suggested an autocatalytic growth mechanism. The corrosion of the inner (pyrolysis) and the outer (hot box) surfaces of the underlying HK40 steel tube had similar features. The chromium rich outer scales were of variable thickness, due to the attack of certain grains, underlying which were zones denuded in carbon precipitates and intergranular silica formation. The major difference was carburization from beneath the decarburized zone at the inner surface. The processes of decarburization, carburization and of intergranular corrosion were interconnected. Carbon pick-up probably resulted from a crevice corrosion mechanism. A general reduction in the nitrogen level through the cracker tube, with enhanced denitriding at both surfaces, originated from a similar mechanism to that responsible for decarburization. The more severe denitriding at the inner surface was derived from chromium nitride conversion to the more stable chromium carbide.

Notes: Abstract A modified fracture toughness test has been used to measure the growth of cracks in unidirectional glass fibre/polyester resin composite materials in the presence of a dilute hydrochloric acid. Crack growth rates perpendicular to the fibre axis have been measured over a range of stress intensities. Scanning electron microscope studies of the fracture surfaces have shown that the micromechanisms of nucleation and propagation are dependent on stress intensity. The use of crack growth data to predict component lifetimes and the existence of inherent flaws in the material are discussed.

Notes: Summary The integument of the woodlouse,Oniscus asellus, consists of a two-layered epicuticle, a largely lamellate procuticle — itself divided into two regions (pre-and postecdysial cuticles), and the epidermis. At the initiation of new cuticle production the epidermal cells become vacuolated and retract away from the cuticle. Apolysis occurs immediately after the cessation of postecdysial cuticle production. The formation of the epicuticle is unique among the arthropods since material aggregates along the distal epidermal membrane. By indenting, doubling back on itself, and incorporating septa, the epicuticle forms surface structures such as plaques and tricorns. The innervation, and so the receptive function of the tricorns is confirmed, but since there is no connection between the old and new receptors during premoult, sensory information from these exoreceptors must be severely curtailed. This may explain the biphasic moult in all isopods since it ensures that only half the body experiences this sensory deprivation at any one time. In terrestrial species there is the additional advantage of restricting the area of permeable new cuticle. The frequency of moulting may be due to the need to renew disrupted receptor surfaces. Tricorns do not appear to be the mechanoreceptors involved in the marked thigmotactic response of woodlice since they do not have the typical internal structure of such receptors; rather, the dendrite —which extends into the lumen of the tricorn —is protected from deformation by the previously unreported combination of a dendritic sheath and a cuticular tube. The modality of tricorns is possibly one of hygro-perception. One of the behavioural responses of woodlice to desiccation is aggregation. The numerical distribution of tricorns over the body surface is admirably suited to assist in the formation and maintenance of such aggregates during desiccation and to their observed dispersal when the relative humidity rises.

Notes: Summary Woodlice are unique among the arthropods in moulting in two halves. The intramoult is 1.8 days inOniscus asellus and results from the two halves being out of synchrony throughout the cycle. In the integument, the initiation of a new moult cycle is heralded by epidermal cell vacuolation; a little later, the subepidermal tissue proliferates and, for a brief time, macrophages appear. The cuticle layers are produced in order, starting with epicuticular structures such as tricorns and plaques, followed by the biphasic epicuticle, the lamellate pre-ecdysial cuticle and, after ecdysis, the lamellate postecdysial cuticle. Epicuticle is formed in a continuous sheet along the distal epidermal membrane and postecdysial cuticle from fibres formed within the cell body — both features not reported for other arthropods. Immediately prior to ecdysis the epicuticle and pre-ecdysial cuticle are highly corrugated and the epidermis very constricted as the width of the ecdysing gap is increased by the new cuticle components withdrawing slightly beneath the old cuticle. At this time the space between the two cuticles appears devoid of the fluid that once occupied it, although the ecdysial membrane is still apparent. After ecdysis the appearance of the epicuticle changes due to chemical events which make it relatively impermeable. The pre-ecdysial cuticle also changes in appearance at this time due to the physical stress of expansion. Large cuticle precursor vesicles, similar to those of other Crustacea, are particularly associated with postecdysial cuticle production. In addition there are numerous small vesicles associated with pre-ecdysial cuticle formation. The epidermal vacuoles disappear as postecdysial cuticle is produced so that, when it is complete, the epidermis is again a narrow cell layer. Apolysis occurs straight after this and shortly afterwards the cycle recommences. Unlike other arthropods woodlice do not expand to break free of the old cuticle instead they walk free of either half and then expand. Experimental evidence is given which suggests that woodlice do not take in water to achieve this expansion but rather, they appear to employ internal hydrostatic pressure. Using published data from woodlice endocrinological studies and the present work a possible method of hormonal control of the biphasic moult is suggested.