| 1. |
- El-Sayed, I., et al.
(författare)
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Synthesis of novel trithiocarbonate-S-oxides
- 2003
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Ingår i: Phosphorus Sulfur and Silicon and the Related Elements. - : Informa UK Limited. - 1042-6507 .- 1563-5325. ; 178:11, s. 2403-2413
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of the trithiocarbonates 3 with m-chloroperoxybenzoic acid (m-CPBA) in chloroform at room temperature provides an efficient stereoselective synthesis of the (E) sulfine 4(a) and (Z) sulfine 4(b). The expected (E) and (Z) configurations of 4(a,b) were confirmed by x-ray structure determination. The Sulfines 4 were further structurally elucidated by their cycloaddition reactions with 2,3-dimethyl-1,3-butadiene in chloroform at room temperature to give the corresponding dihydrothiopyran S-oxides 5(a,b) in a quantitative yield.
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| 2. |
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| 3. |
- El-Sayed, Ashraf, et al.
(författare)
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Flight and molecular modeling study on the response of codling moth, Cydia pomonella (Lepidoptera : Tortricidae) to (E,E)-8,10-dodecadien-1-ol and its geometrical isomers
- 2000
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Ingår i: Zeitschrift für Naturforschung C - A Journal of Biosciences. - : Walter de Gruyter. - 0939-5075 .- 1865-7125. ; 55:11-12, s. 1011-1017
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Tidskriftsartikel (refereegranskat)abstract
- In a previous study we have reported that both (E,Z)-8,10-dodecadienol (E,Z) and (Z,Z) 8,10-dodecadienol (Z,Z) isomers inhibit the attraction of male codling moth, Cydia pomonella L. when added to (E,E)-8,10-dodecadienol (E,E) while the (Z,E)-8,10-dodecadienol (Z,E) isomer induces slight increase in the number of males attracted to the pheromone source. In the present study, we have tested the behavioral activity of the individual geometrical isomers E,Z; Z,E and Z,Z. A few number of codling moth males flew to the Z,E-isomer while the other two isomers (i.e. E,Z and Z,Z) did not elicit any upwind orientation. Analysis of the Right behavior to the E,E- and Z,E-isomer showed significant differences in most of the flight parameters evaluated. Based on the biological observations and molecular modeling, we suggest that the behavioral activity of the Z,E-isomer is due to presence of specific receptors for this isomer on male antennae and not to its structural resemblance to the E,E-isomer. These results underline the importance of the Z,E-isomer in sex attraction of male codling moth.
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| 4. |
- El-Sayed, A. M., et al.
(författare)
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Geographic variation in pheromone chemistry, antennal electrophysiology, and pheromone-mediated trap catch of North American populations of the obliquebanded leafroller
- 2003
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Ingår i: Environmental Entomology. - 0046-225X .- 1938-2936. ; 32:3, s. 470-476
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Tidskriftsartikel (refereegranskat)abstract
- The total and relative amounts of (Z)-11-tetradecenyl acetate (Z11-14:Ac), (E)-11-tetradecenyl acetate (E11-14:Ac), (Z)-11-tetradecen-1-ol (Z11-14:OH) and (Z)-11-tetradecenal (Z11-14:Al), and the EAG response of male antennae to these pheromone gland compounds were compared in laboratory reared Choristoneura rosaceana Harris (Lepidoptera: Tortricidae) from British Columbia, Michigan, Ontario, New York, and Quebec. A field trapping experiment was conducted in each of these locations to determine the effect of Z11-14:Al on the numbers of moths captured. The amount of each of the four pheromone-gland compounds declined successively in moths from British Columbia, Quebec, Ontario, Michigan, and New York. The relative amount of Z11-14:Ac was greatest in moths from New York and smallest in moths from Ontario, whereas the relative amount of E11-14:Ac was greatest in moths from Ontario and smallest in moths from British Columbia. Moths from Ontario, Quebec, British Columbia, Michigan, and New York contained decreasing relative amounts of Z11-14:OH and Z11-14:Al. There was a trend of increasing antenna] sensitivity to each of the four pheromone-gland compounds in moths from New York, Michigan, Ontario, Quebec, and British Columbia. The addition of 1% Z11:Al to a three compound blend of Z11-14:Ac, E11-14:Ac and Z11-14:OH (97:2:1) resulted in a >twofold increase in average trap catch in British Columbia, Ontario, and Quebec; this compound had no effect on trap catch in Michigan or New York.
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| 5. |
- El-Sayed, A M, et al.
(författare)
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Relative attractiveness of (10E)-dodecen-1-yl acetate and (4E,10E)-dodecadien-1-yl acetate to male spotted tentiform leafminers Phyllonorycter blancardella (F.)
- 2004
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Ingår i: Journal of Chemical Ecology. - 0098-0331 .- 1573-1561. ; 30:9, s. 1827-1838
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Tidskriftsartikel (refereegranskat)abstract
- The antennae of male spotted tentiform leafminers, Phyllonorycter blancardella, from Ontario, Canada, exhibited similar electroantennogram responses when stimulated with E10-12:Ac or E4,E10-12:Ac. In field trapping experiments, E10-12:Ac was two-fold or more attractive than E4, E10-12:Ac, and E4,E10-12:Ac did not enhance the attractiveness of E10-12:Ac. E4,E10-12:Ac has not been identified in the pheromone of P. blancardella and it is hypothesized that the structural similarity of this compound and E10-12:Ac, the major pheromone compound of this species, may be responsible for the electrophysiological and behavioral responses to E4,E10-12:Ac. The possible reasons for the disparity between the results of our field trapping experiments and those carried out in Nova Scotia, Canada, and Massachusetts, USA., where E4,E10-12:Ac was found to be two to four times more attractive to P. blancardella than E10-12:Ac, are discussed.
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| 6. |
- El-Sayed, A. M., et al.
(författare)
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Relative attractiveness of (10E)-dodecen-1-yl acetate and (4E,10E)-dodecadien-1-yl acetate to male spotted tentiform leafminers Phyllonorycter blancardella (F.)
- 2004
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Ingår i: Journal of Chemical Ecology. - : Springer. - 0098-0331 .- 1573-1561. ; 30:9, s. 1827-1838
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Tidskriftsartikel (refereegranskat)abstract
- The antennae of male spotted tentiform leafminers, Phyllonorycter blancardella, from Ontario, Canada, exhibited similar electroantennogram responses when stimulated with E10-12:Ac or E4,E10-12:Ac. In field trapping experiments, E10-12:Ac was two-fold or more attractive than E4, E10-12:Ac, and E4,E10-12:Ac did not enhance the attractiveness of E10-12:Ac. E4,E10-12:Ac has not been identified in the pheromone of P. blancardella and it is hypothesized that the structural similarity of this compound and E10-12:Ac, the major pheromone compound of this species, may be responsible for the electrophysiological and behavioral responses to E4,E10-12:Ac. The possible reasons for the disparity between the results of our field trapping experiments and those carried out in Nova Scotia, Canada, and Massachusetts, USA., where E4,E10-12:Ac was found to be two to four times more attractive to P. blancardella than E10-12:Ac, are discussed.
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| 7. |
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| 8. |
- El-Sayed, Eman Mohamed
(författare)
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Brain maturation, cognitive tasks, and quantitative electroencephalography : a study in children with attention deficit hyperactive disorder
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common psychiatric disorders of childhood. Despite a long history, widespread clinical acceptance, and extensive research, the diagnosis and treatment are still controversial. The aim of the thesis was to study the hypothesis that some children with ADHD may show these symptoms due to a slow speed of mental maturation with the possibility of a catch-up. In Study I, the association between ADHD and global maturity was tested using a twin design (incl. 1106 pairs of the 1480 pairs of twins born in Sweden Apr. 1985 - Dec. 1986). The results showed different pathways through which genetic effects may influence the behavior pattern in children with ADHD. Among boys, there are at least two different genetic pathways to explain ADHD, one through predisposition for maturational lag and one specific to ADHD. A different pathway may explain ADHD in girls. In Study II, the relationship between behavior, ADM symptoms and maturity was studied among 1079 pairs of twins from study I using a questionnaire (a global maturity parent's scale) given to the parents. Relationships were found between the maturity factor and the CBCL grouping of syndromes (internalizing, externalizing, total behavior problems score) as well as between the maturity factor and ADHD. From the parents' point of view the behavior problems in their children may be related to maturity. In Study III, a computerized tool, the Gordon Diagnostic System (GDS) was used to test concentration and impulse control comparing 71 children with ADHD (61 boys, 10 girls; mean age 10.5 y) and 98 controls (65 boys, 23 girls; mean age 10.2 y). Differences were found between ADHD children and age-matched control children in each age group. The GDS scores were highly correlated with age with better a performance among the older children, which could support the relevance of the maturational lag hypothesis. In Study IV a possible immature brain processing during concentration was studied comparing 36 children with ADHD (31 boys, 5 girls; mean age 10.5 y) and 63 controls (46 boys, 17 girls; mean age 10.0 y). QEEG techniques were used when the children performed the Vigilance Task of GDS. Compared to controls children with ADHD displayed specific differences in the pattern of frontal, temporal, and parietal brain activation. They had an enhanced slow cortical activity and decreased fast activity similar to younger children. These findings indicate a different arousal level in children with ADHD, which could be due to a delay in functional cortical maturation. In Study V, impulsivity, brain processing and possible immaturity were studied. The same children with ADHD and controls as in study IV performed the Delay Task of GDS during registration of QEEG. In similarity to the results of study IV children with ADHD displayed different electrophysiological reactions, which may indicate that they, like younger children, have problems in cerebral processing when performing a mentally demanding task during a restricted time. In Study VI, the "maturational lag" concept explaining ADHD was discussed over viewing previous and current literature on ADHD. The overview indicates that the DSM criteria of ADHD may be over- inclusive and shows that maturity and developmental aspects are important factors to be included in studies of ADHD. A slow speed in mental development may be of importance for the treatment and prognosis of ADHD. Conclusion. The over all results support the view, that some children with ADHD could represent a continuum of normal childhood behavior with maturational trajectories that are lagging behind and may catch up.
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| 9. |
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| 10. |
- El-Sayed, I., et al.
(författare)
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Diels-Alder reactions of anthracenes with C-sulfonyldithioformates
- 2003
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Ingår i: Heteroatom Chemistry. - : Wiley. - 1042-7163 .- 1098-1071. ; 14:2, s. 170-174
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Tidskriftsartikel (refereegranskat)abstract
- C-Sulfonyldithioformates (2) (R-1 = ArSO2, R 2 = ArS) readily add to anthracene and 9-methylanthracene (1) in a Diels-Alder fashion with formation of 9,10-dihydro-10,9-(epithiomethano)anthracenes (3) which in turn may suffer thermally induced elimination of arenesulfinic acid to yield the 9-anthracenedithiocarboxylic esters (4). The reactions with the unsymmetrical diene 9-methylanthracene take place in a highly stereoselective fashion.
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| 11. |
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| 12. |
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| 13. |
- Guliashvili, T., et al.
(författare)
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The first isolable 2-silenolate
- 2003
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 42:14, s. 1640-1642:42, s. 1640-1642
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Tidskriftsartikel (refereegranskat)
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| 14. |
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| 15. |
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| 16. |
- Skals, Niels, et al.
(författare)
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Quantitative analysis of the effects of ultrasound from an odor sprayer on moth flight behavior
- 2003
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Ingår i: Journal of Chemical Ecology. - 1573-1561. ; 29:1, s. 71-82
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Tidskriftsartikel (refereegranskat)abstract
- A piezoelectric sprayer was recently developed for precision release of odor stimuli in olfactory research. The device replaces conventional dispensers used to release semiochemicals in studies of moth flight toward odor sources. However, the device generates high-frequency sounds in the range that some moths can hear. Ultrasound from the standard set-up sprayer had a considerable impact on flight behavior of the silver Y moth, Autographa gamma, tested in a flight tunnel. It was affected at all behavioral stages when the dispenser was driven at 120 kHz. Only 5% of the moths reached the source when exposed to 120-kHz sound from the dispenser compared to 65% in the control group without sound. The proportion taking flight was also reduced. Hearing threshold curves obtained electrophysiologically revealed that moths were sensitive to the frequency range at which the sprayer was operated and that sound intensity from the sprayer was up to 40 dB above the moths' electrophysiological hearing threshold. The audiogram for A. gamma was similar to audiograms obtained for other noctuids. Hearing sensitivity was highest at around 15 kHz, where the threshold was 35 dB SPL (sound pressure level). The threshold increased with frequency up to 94 dB SPL at 160 kHz. We improved the sprayer to operate at 300 kHz, which is beyond the hearing ability of most insects with ears. At this high frequency, the moths' sensitivity to ultrasound is reduced considerably, and we did not observe any effect on flight behavior compared to a control group without sound. Accordingly, this new piezoelectric sprayer can be used with ultrasound-sensitive insects and insensitive insects alike.
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