Performance of Pb/Zn tolerantFestuca rubra on metalliferous spoil in relation to nitrogen source

In a glasshouse bioassay of acid and calcareous Pb/Zn mine waste, relationships between dry matter yield of Pb/Zn tolerantFestuca rubra L. cv. Merlin, and seven conventional and slow-release nitrogen fertilisers applied as single and split applications were examined against a standard background of phosphate and potassium levels. No significant advantages were found to justify the use of slow release N sources over standard formulations, despite losses due to volatilisation, leaching and immobilisation processes. The fate of the applied nitrogen fertiliser is greatly influenced by the physical and chemical properties of the substrate which must be taken account of in formulating establishment and management specifications.     

Activated sludge characteristics in relation to stable foam formation

This paper examines the hydrophobicity and the surface charge of a range of foaming and nonfoaming activated sludges, together with an appraisal of the species involved. The results show that the solids in foaming sludges possess a higher hydrophobicity than those in nonfoaming sludges. The data also indicate that there are two distinct hydrophobicity/surface charge trends, depending on whether the sludges are foaming or nonfoaming. Sludges in which Nostocoida limicola was the dominant species did not conform to these patterns. In addition, the stability of the foam formed by these sludges was significantly lower.     

Polyunsaturated hydrocarbons in the stable fly

Three triply-unsaturated hydrocarbons were identified from cuticular lipids of male and mixed-sex stable flies,Stomoxys calcitrans. The major compound, (Z,Z)-1,7,13-pentacosatriene, and two minor compounds, (Z,Z)-1,7,13-tetracosatriene and (Z,Z)-1,7,13-tricosatriene, were synthesized. Samples of male and female stable flies that differed in age, seasonality, geographic origin, rearing conditions of adults, and methods of extraction were analyzed for the presence of these triolefins. Females were found to have small quantities of the same C₂₅ triolefin, which appeared to be identical to that in males. No evidence was seen for attraction of males or females to natural or synthetic triolefins.Mention of a proprietary or commercial product does not constitute an endorsement by either the U.S. Department of Agriculture or the University of Florida.     

A two-step depressurization batch process for the formation of bi-modal cell structure polystyrene foams using scCO2

A two-step depressurization batch process is developed to produce bi-modal cell structure polystyrene (PS) foams by using supercritical carbon dioxide (SC-CO₂) as the blowing agent. Bi-modal cell structure foams can be achieved by depressurization in two distinct steps and can be significantly affected by the process parameters. The process conditions at the holding stage between the two steps are the key to controlling the bi-modal cell structure. The findings of this study can help predict the bi-modal cell morphology of PS and other polymers prepared by a two-step depressurization bath process.     

Differential Activity of Peroxidase Isozymes in Response to Wounding, Gypsy Moth, and Plant Hormones in Northern Red Oak (Quercus rubra L.)

We measured total peroxidase activity and the activities of peroxidase isoforms in leaves of red oak (Quercus rubra L.) seedlings exposed to wounding and plant hormones in the greenhouse. Activity of specific peroxidase isoforms was induced differentially by gypsy moth wounding, mechanical wounding, and the wound-associated plant hormone jasmonic acid. Activity of one isoform was enhanced modestly by treatment with salicylate. A study of peroxidase activity in naturally occurring galls elicited on red oak leaves by 12 hymenopteran and dipteran insect species found 16 POD isoforms, 11 of which were differentially induced or suppressed in galls compared with leaves. In both studies, total peroxidase activity as measured spectrophotometrically was not clearly related to activity of these isoforms. These results indicate that red oak seedlings and trees may respond specifically to wounding, particular insects, and plant signals through changes in the activities of individual isozymes.     

Sex pheromone of the stable fly

The cuticular alkenes of the female stable fly,Stomoxys calcitrans (L), which were responsible for inducing male fly copulatory behavior are (Z)-9-hentriacontene, (Z)-9-tritriacontene, 13-methyl-1-hen-triacontene and 13-methyl-1-tritriacontene. The identifications of the branched alkenes and the synthesis of these four compounds are described. Bioassays indicate that these materials in combination with previously described methyl branched alkanes are more active than the individual components.Diptera=Muscidae.Mention of proprietary or commercial products in this paper does not constitute an endorsement of this product by the U.S.D.A.     

Nitrogen fixation by trees in relation to soil nitrogen economy

The N₂-fixing potential (NFP) (i.e. the amount of fixed N₂ in a constraint-free environment) of N₂-fixing trees (NFTs) varies with the genotype. The NFP can be higher than 30-50 g N₂ fixed tree^–1 year^–1 in the most active species, be they leguminous trees such asAlbizia lebbeck, Gliricidia sepium andLeucaena leucocephala, or actinorhizal trees such asCasuarina equisetifolia. The actual amount of nitrogen fixed (ANF) (i.e. the amount of N₂ fixed in the field) is lower than the NFP or even nil because of various constraints, especially drought, nutrient deficiencies, excess of available N and pathogenic nematodes. As tree litters are mineralized, the amount of available N in the soil increases with time, this process leading to the cessation of N₂ fixation in aging plantations. When the mineralization rate is slowed down or inhibited, N₂ fixation can continue. NFTs improve the N status of soils, but the transfer of fixed N to associated plants is not always ensured. Three main approaches are appropriate to increase N₂ fixation: clonal selection of trees combined with vegetative propagation, inoculation with effective rhizobium orFrankia strains, and proper fertilization (especially P). In the absence of major environmental constraints, a positive response to inoculation is expected only when specific (non-promiscuous) NFTs are grown in sites where the density of compatible rhizobia is low or nil. The potentialities of NFTs are far from being fully exploited. Further investigations are proposed and the economics of NFT management is briefly discussed.     

Chemical, Electrophysiological, and Behavioral Investigations on the Sex Pheromone of Lackey Moth, Malacosoma neustrium

The lackey moth Malacosoma neustrium (L.) (Lepidoptera Lasiocampidae) is a common pest of many forest and cultivated broadleaf trees. Analysis by GC-EAD of gland extracts and female effluvia showed the presence of two active peaks that were characterized as (E,Z)-5,7-dodecadienal (E5,Z7-12:Ald) and (E,Z)-5,7-dodecadienol (E5,Z7-12:OH) according to their GC retention times, mass spectra, and electroantennographic activity. (E,Z)-5,7-dodecadienyl acetate (E5,Z7-12:Ac) was also detected in the gland extracts. The average amounts of E5,Z7-12:Ald, E5,Z7-12:OH, and E5,Z7-12:Ac extracted from an abdominal tip were 113.2 +/- 22.0 ng, 29.9 +/- 6.2 ng, and 11.6 +/- 2.0 ng, respectively. In the effluvia from single females, on the average, 1.9 +/- 0.7 ng/min of aldehyde and 0.3 +/- 0.1 ng/min of alcohol were collected. In wind tunnel tests, male behavioral sequences elicited by E5,Z7-12:Ald alone or in 3:1 and 9:1 blends with the corresponding alcohol were similar to those evoked by one female equivalent of sex pheromone gland extract. Field trapping experiments showed that E5,Z7-12:Ald is essential to attract male moths. On adding E5,Z7-12:OH to E5,Z7-12:Ald in 1:3 and 1:9 ratios, male attraction slightly increased whereas in a 1:1 ratio, the attractiveness of E5,Z7-12:Ald was reduced.     

Multivariate study of moose browsing in relation to phenol pattern in pine needles

Extracts of needles from Scots pine,Pinus sylvestris L., grown on fertile (A) or poor (B) soil, and from lodgepole pine,P. contorta Doug. (C), have been analyzed with HPLC and UV detection. By application of multivariate analysis, the phenol pattern was shown to vary between species and between habitats. Within groups A and B, moose food choice was highly correlated to phenol pattern. Concentrations of most of the analyzed compounds were internally correlated. Information related to pine growth rate could also be extracted from the phenolic pattern for A, B, and C. Moose food choice was not correlated to pine growth rate.     

Effect of urea and salt on micelle formation of zwitterionic surfactants

The effect of urea on micelle formation of zwitterionic surfactants was investigated by measuring conductivity, critical micelle concentration (CMC), relative viscosity, and the spectrophotometric shift in wavelength. We examined two zwitterionic surfactants, N,N-dimethyl dodecylamine N-oxide and N,N-dimethyl tetradecylamine N-oxide (DMTAO). The CMC values of the surfactants increased with the addition of urea. Also, the relative viscosity of the surfactant solutions decreased at higher concentrations of urea and increased with increasing KCl concentration. The absorbance maxima of the surfactants decreased with increasing urea concentration.     

6. Ammonium dynamics of puddled soils in relation to growth and yield of lowland rice

The release of non-exchangeable (fixed) NH ₄ ⁺ and the importance of exchangeable NH ₄ ⁺ at transplanting (initial exchangeable NH ₄ ⁺ ) for rice (Oryza sativa L.) growth was studied in representative lowland rice soils of the Philippines.The experiments showed that initial exchangeable ammonium behaved like fertilizer N and thus may serve as a valuable guideline for nitrogen fertilizer application rates when calculated on a hectare basis. By using the¹⁵N tracer technique it was found that nonexchangeable ammonium in soil may contribute to the nitrogen supplying capacity of lowland rice soils. Fixation and release of NH ₄ ⁺ seem to be more dependent on the form of clay minerals than on clay content. In soils rich in vermiculite non-exchangeable ammonium should be considered together with other available N sources such as exchangeable ammonium for N fertilizer recommendations for lowland rice.     

Synthesis of the male stable fly polyene (Z,Z)-1,7,13-pentacosatriene and its geometrical isomers

The four geometrical isomers of 1,7,13-pentacosatriene were synthesized from 1,7-octadiyne. Two of the required isomers were synthesized using known methodology. Hydrogenation of acetylenic linkages were employed to produce predominantly cis alkenes, and alkali metal/amine reduction was used to produce a trans alkene. It was thus possible to produce the (Z,Z) and the (Z,E) isomers. Methods for olefin inversion were then employed to obtain the other two isomers.     

Cessation of polyunsaturated fatty acid formation in four selected filamentous fungi when grown on plant oils

Four fungi,Conidiobolus nanodes, Entomophthora exitalis, Mortierella isabellina, andMucor circinelloides, were grown on various oils (triolein, sesame, safflower, linseed, and oil fromM. isabellina) and produced lipids in which the fatty acids were predominantly the same as those of the original staring substrate. Only in the first two cases was there evidence of a small amount of chain elongation and of fatty acid desaturation taking place. The extent of this was only about 10% of that seen in glucose-grown cells. The apparent repression of the fatty acid desaturases and elongases was not reversed by growing cells on glucose and oils as mixed substrates—the fatty acid profiles were the same as when the fungi had grown in oils alone. Neither was the cessation of polyunsaturated fatty acid synthesis due to the presence of nonoil components (NOC) in the oil. Only the NOC from sesame oil affected one single conversion, that of 20∶3n-3 to 20∶4n–6. We conclude that fatty acid desaturase and elongase systems are repressed either partially or completely in a filamentous fungi grown on triacylglycerol oils.     

Stability of phenolic and protein measures in excised oak foliage

The stability of protein and phenolic measures in excised foliage from two oak species was measured under conditions that simulated the handling and treatment of foliage during insect rearing trials. Excised foliage kept hydrated under refrigeration or insect-rearing conditions maintained stable levels of protein content, proanthocyanidins, gallotannins, total phenolics, and protein-binding capacity for up to 48 hr following field sampling. Measures of protein content, total phenolics, protein-binding capacity, and proanthocyanidins were significantly greater 48–72 hr after field sampling, followed by declines to near field levels within 120 hr.     

Microbial decomposition of ferulic acid in soil

The suppression of plant growth by different phenolic acids is well known. This work was designed to determine if ferulic acid, a known phenolic inhibitor of plant growth, accumulates in the soil and if soil microorganisms could be isolated that metabolize it. Over 99% of the extractable ferulic acid was lost from decaying hackberry leaves in 300 days. During this time the amount in the top 15 cm of soil remained fairly constant at about 30 ppm, except for the March sample which was significantly higher than the rest. Addition of ferulic acid to soil caused an increase in CO₂ evolution and in numbers of a select group of microorganisms.Rhodotorula rubra andCepnalosporium curtipes, which actively metabolize ferulic acid, were isolated, but the metabolic pathways employed appear to be different from the reported one. The reported pathway for ferulic acid breakdown is ferulic acid to vanillic acid to protocatechuic acid to -keto-adipic acid.Rhodotorula Rubra was found to convert ferulic acid to vanillic acid, but no evidence was found for utilization of the rest of the pathway.Cephalosporium curtipes appears to use a different pathway or to metabolize intermediate compounds rapidly without accumulating them, because no phenolic compounds were found during the breakdown of ferulic acid. The presence in the soil of microorganisms that metabolize ferulic acid and other phenolic acids is ecologically significant because such organisms prevent long-term accumulations of these substances, which are toxic to many other microorganisms and higher plants.     

稳定泡沫气/液界面微观形貌的形成机理研究进展

简要介绍了吸附在气泡界面上的表面活性剂发生自聚集现象,形成丰富的纳米微结构及特征形貌.这些微观结构形成了具有良好黏弹性的界面膜,极大地改善了泡沫的稳定性.结合文献调研和作者前期研究结果,分别对稳定气泡界面上不同体系形成的多边形、菜豆形、雪花形、网状及峰谷形貌等的形成机理展开重点评述,指出了该领域目前存在的问题及发展方向.     

Investigations of spherulitic growth in industrial crystallization

The discrimination between crystal growth and aggregation is of crucial importance for the control of morphology and particle size in crystallization processes, as they are influenced in very different ways by the industrial processing environment. A collection of resembling solution-grown polycrystalline particles that differ widely in chemical nature, like elemental nickel, calcium and sodium carbonate, l-glutamic acid and an aromatic amine have been identified to grow by a spherulitic growth mechanism usually only associated with the crystallization of polymers or melts. The particles are not growing by agglomeration of small individual crystals, as often claimed in the literature. The effect of initial supersaturation, temperature and solvent composition on the spherulitic growth of calcium carbonate (vaterite) has been used to demonstrate how spherulites can grow from solution both by central multidirectional growth (in water) and by unidirectional growth followed by low angle branching (in 90 wt% ethylene glycol). The progression of non-crystallographic branching could be monitored as a function of time at intermediate initial supersaturation values, supplying direct visual evidence for spherulitic growth in this system. A reduction in initial supersaturation and temperature resulted in insufficient branching and dumbbell particles, whereas increased levels of supersaturation rapidly produced fully grown spherulites.     

Survival of pine sawflies in cocoon stage in relation to resin acid content of larval food

Several experiments were conducted to determine whether the ingestion of diterpenoids (resin acids) by pine sawfly larvae influences the survival of postlarval stages. Larvae of two diprionid sawfly species were reared on shoots of two Scots pine clones, one with a low (1.5% dry wt) concentration of resin acids and the other with a high (5.2% dry wt) concentration. No significant treatment-related differences were found in any of the experiments with respect to (1) resistance against parasitoids, (2) preference of predatory shrews and carabids, and (3) apparency of cocoons in the field to predators. A preference of sawfly prepupae to spin cocoon in feces from larvae reared on high resin acid needles was found. Possible explanations for these results are discussed. Detection of an unknown compound, possibly a breakdown product of the major resin acid in pine needles (pinifolic acid), in prepupae indicate that resin acids may be metabolized by the sawflies.     

Chemical response of Picea glehnii seed-epiphytic Penicillium species to Pythium vexans under in vitro competitive conditions for mycelial growth

The potential protection of Picea glehnii seedlings from damping-off by seed-epiphytic Penicillium species was investigated. We studied the chemical response of seed-epiphytic Penicillium species (Pen. cyaneum, Pen. damascenum, and Pen. implicatum) to Pythium vexans, a damping-off fungus, in vitro. Penicillium species were cultured singly or cocultured with Pyt. vexans for 14 or 18 d, and mycelial growth, pH of culture filtrate, antifungal activity of the culture filtrate against Pyt. vexans, and the amount of antifungal compound produced by each Penicillium species, were examined. The filtrate of both the single culture of Penicillium and the coculture of Penicillium and Pyt. vexans showed antifungal activity against Pyt. vexans. In a coculture with Pyt. vexans, Pen. cyaneum produced an antifungal compound (patulin) as in the single culture. Pen. damascenum cocultured with Pyt. vexans produced an antifungal compound (citrinin), as it did in the single culture and in larger amounts on day 10. Pen. implicatum produced two antifungal compounds, frequentin and palitantin, and the ratio of frequentin (with higher antifungal activity than palitantin) to palitantin was higher in the coculture with Pyt. vexans than in the single culture. Our results indicate that these Penicillium species have the ability to produce antifungal compounds and to keep antifungal activity under competitive condition with Pyt. vexans. The chemical response of these Penicillium species to Pyt. vexans may contribute to protect P. glehnii seedlings from damage by Pyt. vexans.     

Modeling and simulation of ozone formation from a propene-nitrogen oxide-wet air mixture in a smog-chamber

Ozone formation from a propene-nitrogen oxide-wet air mixture was modeled and simulated by using a detailed reaction model to characterize ozone formation in air pollution. Effects of reaction parameters such as light intensity, initial concentrations of propene and nitrogen oxides, temperature and humidity were investigated. The loss reactions of N₂O₅ by H₂O were incorporated in the model developed in the present study. Results of simulations showed good agreement with smog-chamber experimental data. From the results of simulations it was found that the maximum ozone concentration was little affected by humidity. The model proposed in the present study can be used to predict the amount of ozone formation successfully.