Pheromone production by axenically rearedDendroctonus ponderosae andIps paraconfusus (Coleoptera: Scolytidae)

Mountain pine beetles,Dendroctonus ponderosae Hopkins, and California five-spined ips,Ips paraconfusus Lanier, were reared axenically from surface-sterilized eggs on aseptic pine phloem. After 24 hr in host logs, axenip femaleD. ponderosae and maleI. paraconfusus produced the aggregation pheromones,trans-verbenol (D. ponderosae), and ipsenol and ipsdienol (I. paraconfusus). Emergent, axenically reared maleD. ponderosae contained normal amounts of the pheromoneexo-brevicomin. Axenic femaleD. ponderosae treated with juvenile hormone or exposed to vapors of -pinene, produced the pheromonetrans-verbenol. By 25–35 days after eclosion, axenic females exposed to -pinene vapors produced over six times as muchtrans-verbenol as wild females, suggesting that while microorganisms in wild females may producetrans-verbenol, they may also inhibit production of the pheromone or use it as a substrate.Research supported in part by Natural Sciences and Engineering Research Council, Canada, Operating Grants A3881 and A3706, and H.R. MacMillan Family Fund Fellowships to J.E. Conn and D.W.A. Hunt.     

Mass spectrometry of lipids. II. Monoglycerides,their diacetyl derivatives and their trimethylsilyl ethers

The mass spectra of 1- and 2-monoglycerides, their diacetyl derivatives and their trimethylsilyl (TMS) ether derivatives were recorded at high (80 eV) and low (6–13 eV) voltages. The fatty acid components of these derivatives included the even-numbered saturated acids from capric to arachidic acid plus oleic, linoleic and linolenic acids. Differences between isomeric 1- and 2-monoglycerides were not sufficient to provide a basis for the analysis of these isomers. Mass spectra of the monoglycerides were very similar to the corresponding methyl esters. Mass spectra of the diacetyl derivatives were qualitatively similar to triglycerides of long-chain fatty acids, but parent ions were not observed. The spectra of diacetyl derivatives may be used for distinguishing 1- and 2-monoglycerides, but the spectra of the TMS ethers are better in this regard. The latter derivatives have fragmentation patterns distinct for the 1- and 2-monoglyceride isomers, particularly at low electron voltages. For the first paper in this series, see reference 1.     

Quantitative estimation of esters by thin-layer chromatography

A method for the analysis of fatty esters employing separation by thin-layer chromatography and quantitative determinationvia their hydroxamic acids has been developed. Esters of different types are separated on silica gel plates, the spots or zones are scraped from the plates, the esters are extracted from the silica gel, and the iron hydroxamic acid complexes are formed. The latter are then measured by colorimetry. The method is suitable for analysis of mixtures of ordinary, epoxy, monohydroxy, and dihydroxy fatty esters as well as for mixtures of mono-, di-, and triglycerides. Used in conjunction with gas chromatography this method permits the fatty acid composition of seed oils containing oxygenated fatty acids to be measured in about 3 hours. The amount required for the total analysis is 1 to 10 mg. per determination, depending upon composition. Presented at the Spring Meeting, American Oil Chemists' Society, St. Louis, May, 1–3, 1961. Supported by the Hormel Foundation, the National Institutes of Health (Research Grant H-3559), and the National Dairy Council. Appointment supported by the International Cooperation Administration under the Visiting Research Scientists Program of the U.S.A.     

Mass spectrometry of lipids. I. Cyclopropane fatty acid esters

A method was developed for the almost quantitative conversion of unsaturated esters (from monoenes to tetraenes) to cyclopropanes using diiodomethane and a highly active zinc-copper couple. These derivatives are sufficiently volatile for GLC analysis andcis andtrans isomers can be distinguished by this technique. Equivalent chain lengths of the cyclopropane derivatives were measured on polar and nonpolar phases. The mass spectra of the monocyclopropane compounds are very similar to those of the parent unsaturated esters. Those of dicyclopropanes, however, are quite distinctive so that the original structure of the ester can be deduced. Polycyclopropanes give complex spectra which are difficult to interpret in terms of the position of the original double bonds. Presented at the Symposium on Spectrometry Applied to Lipids, AOCS Meeting, Cincinnati, October, 1965.     

Cell-surface recognition of biotinylated membrane proteins requires very long spacer arms: an example from glucose-transporter probes

Glucose transporters (GLUTs) can be photoaffinity labelled by (diazirinetrifluoroethyl)benzoyl-substituted glucose derivatives and the adduct can be recognised, after detergent solubilisation of membranes, by using streptavidin-based detection systems. However, in intact cells recognition of photolabelled GLUTs by avidin and anti-biotin antibodies only occurs if the bridge between the photoreactive and the biotin moieties has a minimum of 60--70 spacer atoms. We show that a suitably long bridge can be synthesised with a combination of polyethylene glycol and tartarate groups and that introduction of these spacers generates hydrophilic products that can be cleaved with periodate. Introduction of the very long spacers does not appreciably reduce the affinity of interaction of the probes with the transport system.     

Titration without Mixing or Dilution: Sequential Injection of Chemical Sensing Membranes

A novel, miniaturized titration was developed using beads 35 μm in diameter as semisolid aqueous titrant retained in a nonaqueous sample stream. Agarose beads with internally bound pH indicator served as a pH sensing membrane material swollen with aqueous NaOH titrant. The indicator monitored the remaining titrant within the agarose beads during perfusion with H(2)SO(4) in 1-butanol samples. Irreversible reaction of 2 mg bead layers was made possible by automated packing and disposal in a flow cell. This strategy substituted membrane advantages for the burdens of mixing and unnecessary dilution under laminar flow conditions. The agarose environment was conditioned with NaCl to tolerate dissolved salt in the sample. Transmittance measurements were made via fiber optics through FEP PTFE optical windows. A simple inverse relationship held between endpoint volume and acid concentration so that calibration curves were linear, R(2) = 0.9980.     

Hydrodynamics and mass transfer of the coaxial jet mixer in flow injection analysis

A coaxial jet mixer that was previously proposed for rapid and efficient mixing under laminar flow conditions has been studied both theoretically and experimentally. A mathematical model that consists of a set of Navie-Stokes equations that determine the flow velocities and three diffusion-convection reaction equations that determine the reactant and product concentrations has been developed. Equations are solved with the help of finite difference techniques for different flow conditions. The quality of sample and reagent mixing is characterized by the mean product concentration and the amount of product produced. Theoretical results are compared with experimental ones for the mixing of bromothymol blue (a pH indicator) in the outer capillary with NaOH in the inner capillary of the jet mixer.     

The effect of kind of dietary carbohydrate upon the composition of liver fatty acids of the rat

Weanling male rats were fed fat-free diets containing either starch, sucrose, glucose or maltose as principal ingredient. One fourth of each group was fed oral supplements of linoleate. Subgroups of the fat-free groups were killed at 1, 3 and 6 weeks and the lmoleate supplemented group also at 6 weeks. Liver fatty acids were analyzed by gas chromatography. All groups showed changes in fatty acid composition characteristic of essential fatty acid deficiency, and linoleate reversed these changes. The three sugars induced similar compositions of liver fatty acids, but starch stimulated appearance of higher proportions of several odd-chain fatty acids. These included 15:0, 15:1, 17:0, 17:1, 17:2, 19:0, 19:1, 19:2, 19:3 and 19:4. These changes could not be accounted for by their content in the dietary starch. Presented at the AOCS meeting, Houston, April, 1965. Visitor under the AID Program of the United States State Department.     

Group-Based Pfair Scheduling

We consider the problem of supertasking in Pfair-scheduled multiprocessor systems. In this approach, a set of tasks, called component tasks, is assigned to a server task, called a supertask, which is then scheduled as an ordinary Pfair task. Whenever a supertask is scheduled, its processor time is allocated to its component tasks according to an internal scheduling algorithm. Hence, supertasking is an example of hierarchal (or group-based) scheduling. In this paper, we present a generalized framework for “reweighting” supertasks. The goal of reweighting is to assign a fraction of a processor to a given supertask so that all timing requirements of its component tasks are met. We consider the use of both fully preemptive and quantum-based scheduling within a supertask. Work supported by NSF grants CCR 9732916, CCR 9972211, CCR 9988327, ITR 0082866, CCR 0204312, and CCR 0309825. Preliminary versions of some content appeared previously in (Holman and Anderson, 2001, 2003).     

Using a linked soil model emulator and unsaturated zone leaching model to account for preferential flow when assessing the spatially distributed risk of pesticide leaching to groundwater in England and Wales

Although macropore flow is recognized as an important process for the transport of pesticides through a wide range of soils, none of the existing spatially distributed methods for assessing the risk of pesticide leaching to groundwater account for this phenomenon. The present paper presents a spatially distributed modelling system for predicting pesticide losses to groundwater through micro- and macropore flow paths. The system combines a meta version of the mechanistic, dual porosity, preferential flow pesticide leaching model MACRO (the MACRO emulator), which describes pesticide transport and attenuation in the soil zone, to an attenuation factor leaching model for the unsaturated zone. The development of the emulator was based on the results of over 4000 MACRO model simulations. Model runs describe pesticide leaching for the range of soil types, climate regimes, pesticide properties and application patterns in England and Wales. Linking the MACRO emulator to existing spatial databases of soil, climate and compound-specific loads allowed the prediction of the concentration of pesticide leaching from the base of the soil profile (at 1 m depth) for a wide range of pesticides. Attenuation and retardation of the pesticide during transit through the unsaturated zone to the watertable was simulated using the substrate attenuation factor model AQUAT. The MACRO emulator simulated pesticide loss in 10 of 12 lysimeter soil-pesticide combinations, for which pesticide leaching was shown to occur and also successfully predicted no loss from 3 soil-pesticide combinations. Although the qualitative aspect of leaching was satisfactorily predicted, actual pesticide concentrations in leachate were relatively poorly predicted. At the national scale, the linked MACRO emulator/AQUAT system was found to predict the relative order of, and realistic regional patterns of, pesticide leaching for atrazine, isoproturon, chlorotoluron and lindane. The methodology provides a first-step assessment of the potential for pesticide leaching to groundwater in England and Wales. Further research is required to improve the modelling concept proposed. The system can be used to refine regional groundwater monitoring system designs and sampling strategies and improve the cost-effectiveness of the measures needed to achieve 'good status' of groundwater quality as required by the Water Framework Directive.