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The anaerobic digestion of cheese whey was studied in a UASB reactor. The profiles of the reactor, i.e., the distributions of the substrate concentration and pH under different operating conditions were developed. From the concentrations of substrates measured at various levels above the bottom of the reactor, two reaction stages, namely acidogenesis and methanogenesis, were distinguished. The instability caused by high influent concentration was interpreted as the accumulation of VFAs in the acidogenic stage beyond the assimilative capacity of the methanogenic stage. A range of stable operating conditions was predicted from the results of the profile measurements. The optimal influent concentration was found to be between 25 and 30 g COD/L at an HRT of 5 days for system stability. Other options fro stability control were discussed.

Two simultaneous fermentations were performed at 26 degrees C with simultaneous inocula using Clostridium saccharoperbutylacetonicum. Fermentation 1 prevented the gas formed by the biomass from escaping the fermentor while 2 allowed the gas formed to escape. Fermentor 1 provided for the production of butanol, acetone, and ethanol, while when the H(2) formed was allowed to escape with fermentor 2, neither butanol nor acetone were produced. Ethanol was also formed in both fermentors and began along with the initial growth of biomass and continued until the fermentations were complete. Butanol and acetone production began after biomass growth had reached a maximum and began to subside. The butanol-acetone-ethanol millimolar yields and ratios were 38:1:14 respectively. The fermentor 2 results show that a yield of 2.1 L H(2), 93 or 370 mmol H(2)/mol glucose, was formed only during the growing stage of growth; neither butanol nor acetone were produced; ethanol was formed throughout the fermentation, reaching a yield of 15.2 mmolar. It appears that hydrogen gas is required for butanol production during the resting stage of growth.

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Chromenes (benzopyrans), common to many genera of the Asteraceae, are lethal to the neonate variegated cutworm, Peridrorna saucia Hiibner, when presented on the inner walls of glass vials at concentrations of 1.0 #mol/vial or less. Closely related benzofurans, including some from the same plants, are relatively inactive at these concentrations. The most potent of seven naturally-occurring and four derived chromenes is the well known allatocidin, precocene II, with an LDs0 of 0.134 t~mol/vial or 0.67 #g/cm 2. A more widely distributed chromene, desmethoxyencecalin, is also relatively toxic with an LDs0 of 0.98 #g/cm 2.Structure-activity comparisons of the chromenes tested in this study suggest that the presence of a free hydroxyl group at either C-7 or C-11 significantly diminishes activity. Saturation of the 3,4 double bond, which destroys the allatocidal activity of the precocenes, diminishes, but does not alleviate, contact toxicity of chromenes to cutworm larvae. Brief exposure (24 h) of 2-day-old larvae to chromene residues significantly inhibits subsequent larval growth. The degree of chronic growth inhibition (sublethal toxicity) from five different chromenes is highly correlated to their lethal potencies to neonate larvae.

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Chromenes (benzopyrans), common to many genera of the Asteraceae, are lethal to the neonate variegated cutworm, Peridroma saucia Hübner, when presented on the inner walls of glass vials at concentrations of 1.0 μmol/vial or less. Closely related benzofurans, including some from the same plants, are relatively inactive at these concentrations. The most potent of seven naturally‐occurring and four derived chromenes is the well known allatocidin, precocene II, with an LD50 of 0.134 μmol/vial or 0.67 μg/cm2. A more widely distributed chromene, desmethoxyencecalin, is also relatively toxic with an LD50 of 0.98 μg/cm2. Structure‐activity comparisons of the chromenes tested in this study suggest that the presence of a free hydroxyl group at either C‐7 or C‐11 significantly diminishes activity. Saturation of the 3,4 double bond, which destroys the allatocidal activity of the precocenes, diminishes, but does not alleviate, contact toxicity of chromenes to cutworm larvae. Brief exposure (24 h) of 2‐day‐old larvae to chromene residues significantly inhibits subsequent larval growth. The degree of chronic growth inhibition (sublethal toxicity) from five different chromenes is highly correlated to their lethal potencies to neonate larvae. ZUSAMMENFASSUNG Insektizide Chromene aus Asteraceen: Struktur‐Aktivitäts‐Beziehungen Verschiedene Chromene (Benzopyrane), die in einer Vielzahl von Gattungen aus der Familie der Asteraceae vorkommen, erwiesen sich als insektizid gegenüber frischgeschlüpften Raupen von Peridroma saucia. Die getesteten Substanzen wurden dabei als Film an den Innenwänden von Glass‐Scintillationsgefäßen in Konzentrationen bis zu 1 μmol/Gefäß appliziert und die Raupen über 24 h in diesen Gefäßen gehalten. Den Chromenen biogenetisch ähnliche Benzofurane, die oft gemeinsam in Asteraceen gefunden werden, zeigten im Vergleich keine oder nur schwache insektizide Wirkungen. Von sieben natürlich vorkommenden und vier durch Partialsynthesen getesteten Chromenen erwies sich das bekannte Allatocidin Precocen II als die aktivste Verbindung. Der LD 50‐Wert dieses Chromens betrug 0.134 μmol/Scintillationsgefäß oder 0.67 μg/cm2. Das weitaus häufigere Chromen Desmethoxyencecalin wies im Vergleich einen LD 50‐Wert von 0.98 μg/cm2 in diesem Biotest auf. Struktur/Aktivitätsuntersuchungen der getesteten Chromene zeigten, daß die Anwesenheit einer OH‐Gruppe an den Positionen C‐7 und C‐11 zu einer deutlichten Aktivitätsminderung führte. Hydrierung der heterocyclischen Doppelbindung, die einen völligen Verlust der allatociden Wirkung von Precocenen bewirkt, verringerte die Kontakttoxizität der Chromene auf 50% der ursprünglichen Aktivität. Ein kurzer Kontakt (24 h) von zwei Tage alten Peridroma‐Raupen des ersten Larvenstadiums mit den Chromenen resultierte in einer signifikanten Verringerung des nachfolgenden Wachstums der Raupen auf künstlicher Diät. Die deutlichsten Struktur/Aktivitätsbeziehungen, die in der vorliegenden Arbeit ermittelt wurden, lassen sich wie folgt zusammenfassen: 1) Die Gegenwart eines Furanringes statt ...