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  • 1991  (96)
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  • Articles  (96)
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  • Springer  (96)
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  • 1
    Electronic Resource
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    Springer
    Entomologia experimentalis et applicata 59 (1991), S. 75-78 
    ISSN: 1570-7458
    Keywords: Leptinotarsa decemlineata Say ; Coleoptera ; Chrysomelidae ; female sex pheromone ; screening method ; mating behaviour ; tactile stimuli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 2
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    Entomologia experimentalis et applicata 61 (1991), S. 255-263 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Bruchidae ; Bruchidius atrolineatus ; larval crowding ; post-embryonic development ; intracotyledonary mortality ; weight of emerging adults ; reproductive diapause
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Chez Bruchidius atrolineatus, l'accroissement de la densité larvaire à l'intérieur de la graine entraîne une augmentation de la mortalité alors que la réduction de poids des individus à l'émergence est relativement limitée. L'accroissement de la densité larvaire provoque une augmentation du taux d'adultes en diapause reproductrice, dans certaines conditions thermopériodiques. Dans d'autres conditions, permenttant l'émergence d'un fort taux d'adultes diapausants, l'effet de la densité larvaire est nul. Lorsque l'on analyse l'effet de la densité chez les individus d'une souche ne présentant pas de phénomène de diapause, il n'y a pas de corrélation entre la durée de développement et le poids des adultes. Par contre, lorsqu'il y a émergence d'adultes sexuellement actifs et diapausants, il existe une corrélation entre la durée de développement et le poids des adultes émergeants. Cette corrélation est due au fait que les adultes diapausants, qui présentent les durées de développement les plus longues, sont ceux qui ont les poids les plus faibles.
    Notes: Abstract In Bruschidius atrolineatus (Pic), an increase in larval density inside the seed led to a reduction in the survival rate during post-embryonic development, with only a limited decrease in the weight of adults. A high larval density increased the proportion of adults in reproductive diapause under certain thermoperiodic conditions. Under other conditions that already promote the emergence of a high proportion of diapausing beetles, an increase in larval density had no effect on diapause. There was no correlation between the larval developmental time and the weights of adults in a strain with a very low incidence of diapause. However, such a correlation was observed when both sexuallyactive and diapausing beetles emerged. This correlation was explained by the longer developmental times and lower weights of diapausing beetles.
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  • 3
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    Applied physics 52 (1991), S. 84-89 
    ISSN: 1432-0649
    Keywords: 36.40 ; 42.65 ; 47.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Coherent Stokes and anti-Stokes Raman scattering CSRS and CARS have been employed to study the spectroscopy of nitrogen molecules and clusters in the expansion of a supersonic jet. In the vibrational spectrum, at strong stagnation conditions, an intense redshifted peak is observed which can be assigned to the intramolecular vibrations in large N2 clusters having adopted the β-phase structure. Another weak feature is assigned to nitrogen clusters in the α-phase. In the rotational region of the spectrum only monomer features have been observed. The failing to observe librational motions is consistent with the finding that the nitrogen clusters are predominantly in the orientationally unordered β-phase. The low rotational temperature suggests supercooling of the β-phase.
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  • 4
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    Applied physics 53 (1991), S. 353-361 
    ISSN: 1432-0649
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We are investigating the thermodynamic conditions under which condensation occurs in laser ablated copper plasma plumes. The plasma is created by XeCl excimer laser ablation (308 nm, 300 mJ/pulse) at power densities from 500–1000 MW/cm2 into backing pressures of helium in the range 0–50 torr. We use laser-induced fluorescence (LIF) to probe velocity and relative density of both atomic copper and the copper dimer molecule, Cu2, which is formed during condensation onset. At low pressure (10 mtorr), the atomic Cu velocity peaks at approximately 2×106 cm/s. Copper dimer time-of-flight data suggest that condensation onset occurs after the Cu atoms have slowed very significantly. Excitation scans of the Cu2A-X (0,0) and (1,1) bands yield a rotational and vibrational temperature in the neighborhood of 300 K for all conditions studied. Such low temperatures support the theory that Cu2 is formed under thermally and translationally cold conditions. Direct laser beam absorption is used to determine the number density of atomic copper. Typical densities attained with 5 torr of helium backing gas are 6–8×1013 cm−3. Rayleigh scattering from particulate is easily observable under conditions favorable to particulate production.
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  • 5
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    Applied physics 52 (1991), S. 213-217 
    ISSN: 1432-0630
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Mass spectroscopic studies of the neutral particles sputtered by Ar+ ions at 8 keV from polycrystaline samples have been performed, using non-resonant laser ionization and subsequent time-of-flight mass spectroscopy. Besides sputtered atoms, also dimer and trimer contributions in the order of 10−1 to 10−2 and 10−3 to 10−4, respectively, are found in the sputtered flux. The data obtained here together with previously published data by other groups for different bombarding energies provide strong support for the validity of the recombination model.
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  • 6
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    Applied physics 52 (1991), S. 445-447 
    ISSN: 1432-0630
    Keywords: 82.65 ; 36.40 ; 73.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Desorption of K atoms by laser-excitation of surface plasmons in small K particles is reported. The desorption rate has been measured for different laser wavelengths and particle sizes. Time-of-flight measurements reveal a kinetic energy of the desorbed atoms of Ekin=0.13(3) eV. From the experimental data it is concluded that the desorption mechanism is non-thermal in nature. Comparison of the results reported here with our earlier work on Na desorption is made.
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  • 7
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; coccinelline ; Coleoptera ; Coccinellidae ; Coccinella septempunctata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 7-spot ladybirds secrete alkaloid (coccinelline)-rich fluid (reflex blood) from leg joints as a defence mechanism against predators. A technique is described that enables the collection and accurate quantification of reflex blood produced, and the amount of coccinelline therein. Coccinelline was found distributed throughout the body, although concentrated in the reflex blood. Reflex blood was collected from a large set of beetles at several time points. Significant variation was found among beetles in the amount of reflex blood produced (for males and for females corrected for body weight) and the coccinelline concentration of the reflex blood. The results are discussed in relation to automimicry and the maintenance of variation through energy trade-offs. The relationships between tendency to aggregate, ability to reflex bleed and the possession of aposematic coloration are also considered.
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  • 8
    ISSN: 1423-0445
    Keywords: chemical defence ; mimicry ; reflex bleeding ; variation ; alkaloid ; adaline ; Coleoptera ; Coccinellidae ; Adalia bipunctata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 2-spot ladybirds secrete alkaloid (adaline)-rich defence fluid (reflex blood) in response to predator attack. Reflex fluid was collected from individual ladybirds and weighed and the alkaloid content measured by GC. The amount of fluid produced built up rapidly following winter hibernation in animals feeding on aphids. The concentration of adaline in the fluid was highest in the first bleeding after winter hibernation. A large sample of beetles was reflex bled several times. Significant among beetle variation was found in the amount of fluid produced and the concentration of the reflex blood. The results are discussed in relation to the possibility that 2-spot ladybirds are Batesian mimics of 7-spot ladybirds and to the possible functions of adaline.
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  • 9
    ISSN: 1423-0445
    Keywords: defensive secretion ; hot secretion ; elytral flanges ; evolution ; benzoquinones ; hydrocarbons ; bombardier beetle ; Coleoptera ; Carabidae ; Paussinae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Australian bombardier beetle,Mystropomus regularis, sprays a mixture of quinones (1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone) and hydrocarbons (principallyn-pentadecane). The defensive fluid ist generated explosively in two-chambered glands, and is ejected audibly and hot (maximal recorded temperature = 59°C).Mystropomus is a member of the paussoid lineage of bombardiers. In common with other members of the group, it has a pair of elytral flanges (flanges of Coanda), associated with the gland openings, that serve as launching guides for anteriorly-aimed ejections of spray. It is argued thatMystropomus may be the least derived of flanged paussoids, and the closest living relative of the most primitive of extant bombardiers (Metriini).
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  • 10
    ISSN: 1423-0445
    Keywords: pyrrolizidine alkaloid N-oxides ; alkaloid sequestration ; defensive secretion ; host plant ; Coleoptera ; Chrysomelidae ; Oreina ; Asteraceae ; Adenostyles alliariae ; Senecio fuchsii ; Petasites paradoxus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima.
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  • 11
    ISSN: 1423-0445
    Keywords: larval frass ; predator ; prey ; biological control ; kairomones ; Rhizophagus grandis ; Dendroctonus micans ; Coleoptera ; Rhizophagidae ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Adults of the predatory beetleRhizophagus grandis are strongly attracted to both adult and larval frass of its specific prey,Dendroctonus micans, in walking bioassays. Spruce bark and resin are relatively unattractive. Solvent extracts of larval frass that were attractive toR. grandis adults in a flight wind tunnel contained a mixture of monoterpenes of host plant origin. A synthetic mixture of these monoterpenes, (+)—α-pinene, (−)—β-pinene, β-phellandrene,dl limonene and 3-carene, was responsible for 70–80% of the activity of the most attractive extract. We suggest that a blend of monoterpenes in frass acts as a kairomone forR. grandis but that attraction to monoterpenes is only the first of a sequence of behavioural responses that ensures successful host location and identification.
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  • 12
    ISSN: 1573-1561
    Keywords: Aggregation pheromone ; Coleoptera ; Curculionidae ; Rhynchophorus palmarum ; American palm weevil ; (2E)-6-methy1-2-hepten-4-ol ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Male American palm weevils (APWs),Rhynchophorus palmarum (L.) produced two sex-specific compounds, which were disclosed by volatile collections on Supelpak-2 and gas chromatography. One was a minor compound, not always detected. The major male-produced volatile was identified as (2E)-6-methyl-2-hepten-4-ol through coupled gas chromatography-mass spectrometry and gas chromatography-Fourier transform infrared spectrometry, proton nuclear magnetic resonance spectrometry, and rational synthesis. We propose the trivial name rhynchophorol for this new molecule, which proved to be the essential component of the APW aggregation pheromone by electroantennography, coupled gas chromatography-electroantennography and behavioral bioassays.
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  • 13
    ISSN: 1573-1561
    Keywords: Dendroctonus brevicomis ; Ips paraconfusus ; bark beetle ; verbenone ; ipsdienol ; pheromones ; inhibitors ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract DendroctonusBrevicomis andIps paraconfusus are sympatric bark beetle species colonizingPinus ponderosa in western North America. Interspecific and intraspecific competition for resources is, in part, mediated through semiochemicals. The response ofD. brevicomis to its attractant pheromone was significantly reduced by simultaneous release of either verbenone or racemic ipsdienol. Trap catch was significantly further reduced by including both inhibitors with the attractant pheromones. However, although the response ofIps paraconfusus was significantly inhibited with the addition of either verbenone or racemic ipsdienol, both compounds together did not result in a significant further reduction in trap catch. There was a trend for greater reduction in response ofD. brevicomis to attractant pheromones with increased release rates of either 69% (+)-/31% (−)-verbenone or 84% (−)-/16% (+)-verbenone. Response of associates to attractants and inhibitor combinations was also determined.
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  • 14
    ISSN: 1573-1561
    Keywords: Sitophilus oryzae ; Curculionidae ; Rhyzopertha dominica ; Bostrichidae ; Oryzaephilus surinamensis ; Cucujidae ; Tribolium castaneum ; Tenebrionidae ; Coleoptera ; essential oils ; fumigant toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The fumigant toxicity of 28 essential oils extracted from various spice and herb plants and some of their major constituents were assessed for adult coleopteransRhyzopertha dominica, Oryzaephilus surinamensis, Tribolium castaneum, andSitophilus oryzae. Three groups of active materials were distinguished: (1) The compounds terpinen 4-ol, 1,8-cineole, and the essential oils of three-lobed sage, sage, bay laurel, rosemary, and lavender were most active againstR. dominica; (2) The compounds linalool,α-terpineol, and carvacrol and the essential oils of oregano, basil, Syrian marjoram, and thyme were most active againstO. surinamensis; and (3) the compound 1,8-cineole and the essential oils anise and peppermint were active againstT. castaneum.
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  • 15
    ISSN: 1573-1561
    Keywords: Ips pini ; Thanasimus dubius ; Coleoptera ; Scolytidae ; Cleridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The bark beetleIps pini (Say) displays variation in its response to and production of enantiomeric blends of its pheromone ipsdienol. One of the principal predators ofIps pini isThanasimus dubius (F.), which uses ipsdienol as a kairomone for prey location. During 1988 and 1989, in Wisconsin and Michigan, the response of both species to a range of enantiomeric blends of ipsdienol was investigated. Blends tested had the following ratios of the (S)-(+) to (R)-(−) enantiomers: 3%∶97%, 25%∶75%, 50%∶50%, 75%∶25%, and 97%∶3%. Either75% (+) ∶ 25% (−) or 50% (+)∶ 50% (−) ipsdienol captured the mostIps pini in both years at both sites. The 25% (+)∶75% (−) blend also caught moreIps pini than the control during both years at both sites. All blends tested were attractive toThanasimus dubius in both years at both locations. Blend preferences of both species were variable and labile at both sites. Response patterns of both species in Wisconsin were different from those in Michigan each year. Furthermore, response patterns of both species to the ipsdienol blends changed from 1988 to 1989 at both locations. A genetic component to this variation would permit predator-prey coevolution, as well as the development of resistance byIps pini to management strategies based on mass-trapping with single blends.
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  • 16
    ISSN: 1573-1561
    Keywords: Coleoptera ; Curculionidae ; Hypera postica ; alfalfa weevil ; Medicago rugosa ; Medicago sativa ; insect resistance ; (Z)-oxacyclotridec10-en-2-one ; cis-9-dodecen-12-olide ; (Z)-12-hydroxydodec-9-enoic acid lactone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Steam distillate prepared from leaves ofMedicago rugosa Desr. could inhibit feeding by adult alfalfa weevils (Hypera postica (Gyll.) on membrane filters, whereas an equivalent amount of steam distillate prepared usingM. sativa L. had no effect on weevil feeding. Earlier work established that a 12-carbon lactone, (Z)-oxacyclotridec-10-en-2-one, was responsible for the feeding deterrent properties of the steam distillate fromM. rugosa. The concentration of this volatile varied with plant age and leaf position. The maximum concentration in leaves ofM. rugosa (area basis) was estimated, on the basis of tests using an inert substrate, to be too low to cause a detectable inhibition of feeding. No correlation between lactone content and weevil feeding was detected when leaves from similar positions on plants of different ages were used in a multiple choice bioassay. Although small amounts (〈 12.5μg) of (Z)-oxacyclotridec-10-en-2-one can inhibit adult alfalfa weevil feeding on 13-mm-diameter membrane filters, because leaf concentrations (area basis) of this compound are lower than required to cause a detectable inhibition of feeding on the inert substrate, and because concentrations do not correlate with weevil feeding, it is unlikely that this lactone is responsible for resistance to adult alfalfa weevil feeding exhibited byM. rugosa.
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  • 17
    ISSN: 1573-1561
    Keywords: Ahasverus advena (Waltl) ; foreign grain beetle ; Coleoptera ; Cucujidae ; 1-octen-3-ol ; volatile attractant ; aggregation pheromone ; population density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Volatiles were captured on Porapak Q from foreign grain beetles,Ahasverus advena (Waltl), feeding on rolled oats at various population densities. At low population density, males, females, and mixed-sex beetles four to six weeks posteclosion and older produced 1-octen-3-ol. Mixed-sex beetles emitted almost pure (R)-(−) enantiomer. Weekly production rates of 1-octen-3-ol by males were at least four times greater than those of females. Production of 1-octen-3-ol was barely detectable in volatiles from mixed-sex adults maintained at the highest population density. Laboratory bioassays in a two-choice, pitfall olfactometer modified to retain responding beetles revealed that 1-octen-3-ol serves as an aggregation pheromone forA. advena. Both racemic and chiral 1-octen-3-ols were good attractants for mixed-sex adults in the pitfall olfactometer.
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  • 18
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    Journal of chemical ecology 17 (1991), S. 1517-1527 
    ISSN: 1573-1561
    Keywords: Pheromone ; ipsenol ; cis-verbenol ; chirality ; Ips latidens ; Coleoptera ; Scolytidae ; predator ; kairomone ; Enoclerus sphegeus ; Thanasimus undatulus ; Cleridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Ipsenol was identified from the frass of male, but not female,Ips latidens from British Columbia, feeding in phloem tissue of lodgepole pine,Pinus contorta var.latifolia. The responses ofJ. latidens to sources of ips-enol andcis-verbenol were determined with multiple-funnel traps in stands of lodgepole pine in British Columbia. Ipsenol attracted both male and femaleI. latidens, verifying that it is a pheromone for this species. MaleI. latidens showed a slight preference for (S)-(−)-ipsenol.cis-Verbenol was not produced by beetles of either sex and, in contrast to an earlier report, both enantiomers inhibited attraction to ipsenol-baited traps. The predators,Enoclerus sphegeus andThanasimus undatulus (Cleridae), were attracted to traps baited withcis-verbenol and ipsenol.
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  • 19
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    Journal of chemical ecology 17 (1991), S. 2021-2034 
    ISSN: 1573-1561
    Keywords: Rapeseed ; Brassica spp. ; isothiocyanate ; thiocyanate ; defatted ; seed meal ; allelochemicals ; Limonius infuscatus ; wireworms ; Coleoptera ; Elateridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A variety of plant pests are suppressed by the incorporation of cruciferous plant material into soil. Although this effect is attributed to decomposition of glucosinolates into toxic products, little is known concerning glucosinolate degradation in the soil environment. Arenas (30 × 18 × 8 cm) that contained soil amended with 30 g defatted winter rapeseed meal (Brassica napus L.)/kg soil on one half and unamended soil on the other were constructed. Isothiocyanate concentrations in the soil were measured using infrared analysis of CC14 extracts, and ionic thiocyanate (SCN−) using ion chromatography on aqueous extracts. Quantities were monitored during a 100-hr time period in conjunction with a wireworm bioassay. Isothiocyanate production reached a maximum of 301 nmol/g soil at 2 hr, but decreased by 90% within 24 hr. Production of SCN− reached a maximum of 180 nmol/g soil at 8 hr but persisted longer than isothiocyanate. Separate late instar wire-worms (Limonius infuscatus Mots.) were repelled by the presence of rapeseed meal in less than 24 hr even though the meal was shown in separate experiments not to be toxic. We propose that rapidly produced isothiocyanates are responsible for this repellency, but other products such as SCN− may play a role.
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  • 20
    ISSN: 1573-1561
    Keywords: Polygraphus rufipennis ; Coleoptera ; Scolytidae ; aggregation pheromone ; bark beetle ; black spruce ; 3-methyl-3-buten-1-ol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Porapak Q-captured volatiles of malePolygraphus rufipennis (Kirby) boring in black spruce and white spruce from Newfoundland and British Columbia, respectively, contained 3-methyl-3-buten-1-ol. Volatiles from logs in which the males had been joined by females contained the compound in reduced quantities. Hindgut extracts from male and femaleP. rufipennis disclosed no male-specific volatiles, but 3-methyl-3-buten-1-ol was detected in extracts of male-produced frass. The compound was not present in extracts from fresh phloem tissue.P. rufipennis of both sexes responded strongly in the field to traps baited with 3-methyl-3-buten-1-ol released at 4390 μg/day. There was little response to unbaited traps, fresh uninfested black spruce logs, or to 3-methyl-3-buten-1-ol released at lower rates. Combination of 3-methyl-3-buten-1-ol with either one of five terpenes prevalent in black spruce did not enhance beetle catch. Approximately half of 20 black spruce trees baited with 3-methyl-3-buten-1-ol were attacked, compared to 20.0% of 10 unbaited control trees. This new aggregation pheromone could be used to monitor or manageP. rufipennis populations.
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  • 21
    ISSN: 1573-1561
    Keywords: Dendroctonus micans ; Dendroctonus valens ; Rhizophagus grandis ; Coleoptera ; Rhizophagidae ; Scolytidae ; oviposition stimuli ; biological control ; monoterpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract During a laboratory study evaluatingRhizophagus grandis (a specific native predator of the Eurasian bark beetle,Dendroctonus micans), as a potential biocontrol agent against the North American bark beetle,Dendroctonus valens, it was found that feeding larvae and laboratory-produced frass of the potential prey elicited very high oviposition responses in the predator. Comparative chemical analysis of this laboratory-produced larval frass revealed that one major volatile compound, (-)-fenchone, is associated with the larvae of bothDendroctonus species.D. micans also generated pinocamphone while oxygenated monoterpenes in the frass ofD. valens were camphor,cis-4-thujanol, fenchol, terpinen-4-ol, myrtenal, pinocarvone, borneol, verbenone, piperitone, campholenaldehyde,trans-myrtanol,cis-myrtanol,p-cymen-8-ol and 5-oxo-camphor. This range of prey-produced compounds with a possible biological effect onR. grandis was narrowed down subsequent to comparative analysis of field-collected larval frass. (-)-Fenchone, pinocamphone, camphor, terpinen-4-ol, borneol, fenchol, and verbenone were found to be common to both prey species. A mixture of these seven components was tested in a bioassay, where it elicited as much oviposition as did larval frass ofD. micans. The oviposition stimulants forR. grandis are thus clearly among the mixture's constituents.
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  • 22
    ISSN: 1573-1561
    Keywords: Coleoptera ; Nitidulidae ; Carpophilus hemipterus ; dried fruit-beetle ; host-finding ; yeast ; wind tunnel ; attaction ; volatiles ; headspace
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The chemical basis underlying orientation to fruit and fungal odors was investigated for the dried-fruit beetle,Carpophilus hemipterus (L.). In wind-tunnel bioassays of walking and flight response from 1.8 m, beetles were attracted to odors of the yeastSaccharomyces cerevisiae on agar, aseptic banana, or banana inoculated withS. cerevisiae, although both banana substrates elicited greater response than the yeast alone. When presented in a two-choice bioassay, the yeast-inoculated banana attracted approximately twice as many beetles as did the aseptic banana. GC-MS analysis of the headspace volatiles above these odor sources revealed a somewhat more complex and concentrated volatile profile for yeast-inoculated banana than for aseptic banana. The odor from yeast on agar had fewer components, and these were present at lower concentrations than the odors of either banana substrate. By blending mineral-oil or aqueous solutions of the 18 components of inoculated-banana odor in varying concentrations, it was possible to mimic closely the headspace profile of the natural odor. This synthetic odor also elicited beetle attraction in the wind tunnel at levels comparable to the inoculated banana. Through a series of bioassays in which individual components were subtracted from or added to a synthetic odor blend, it was determined that ethyl acetate, acetaldehyde, 2-pentanol, and 3-methylbutanol comprised the simplest blend of compounds evoking full behavioral response. However, 2-methylpropanol or butanol were apparently interchangeable with 3-methylbutanol in this blend, and comparable response could also be elicited by replacing acetaldehyde with a combination of both 2-pentanone and 3-hydroxy-2-butanone. Thus, our results suggest that this generalist insect herbivore locates its hosts by a long-range response to a variety of blends of common fruit volatiles, whose concentrations are enhanced by fungi.
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    Journal of chemical ecology 17 (1991), S. 2323-2332 
    ISSN: 1573-1561
    Keywords: Galeruca tanaceti ; Coleoptera ; Chrysomelidae ; anthraquinones ; eggs ; larvae ; hemolymph ; ovaries ; Tanacetum vulgäre ; Achillea millefolium ; feeding deterrence
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The overwintering eggs and the larvae of the leaf beetleGaleruca tanaceti (L.) contain hydroxylated anthraquinones. In both developmental stages, l,8-dihydroxy-3-methylanthraquinone (= chrysophanol) and 1,8-di-hydroxyanthraquinone (= chrysazin) were detected by GC-MS and GC-FTIR analyses. In the eggs, chrysazin was found only in traces. Anthraquinones were also present in ovaries and hemolymph of gravid females, which were investigated in order to examine the incorporation of these substances into the eggs. Neither in acidified nor in nonacidified extracts of the host plantsTanacetum vulgäre L. andAchillea millefolium L. were anthraquinones found. The activity of these anthraquinones as chemical defense substances was proved in bioassays with the antMyrmica ruginodis NYL. Further possible biological significances of anthraquinones are discussed.
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    Journal of chemical ecology 17 (1991), S. 989-1005 
    ISSN: 1573-1561
    Keywords: Host-plant resistance ; host-plant selection ; glycoalkaioids ; Leptinotarsa decemlineata ; Coleoptera ; Chrysomelidae ; Lycopersicon ; α-tomatine
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The role of the steroidal glycoalkaloid α-tomatine in the hostplant resistance of tomato to the Colorado potato beetle,Leptinotarsa decemlineata (Say) was examined in short- (24 hr; using first- and fourth-instar larvae) and long-term (first-instar larvae reared through the prepupal stage) feeding experiments. Consumption rate, growth rate, efficiency of conversion of ingested food to body mass, and survival were compared forL. decemlineata provided foliage from susceptible (Lycopersicon esculetum Mill. cv. Walter), resistant (L. hirsutum f.Glabratum C.H. Mull accession PI 134417), and F1 hybrid plants. Values obtained for dietetic indices were regressed against corresponding values for α-tomatine content of foliage provided to larvae. Differences in dietetic indices could not be attributed to variation in foliar α-tomatine content despite a long-standing literature showing theex planta α-tomatine inhibits feeding and growth byL. decemlineata.
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  • 25
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    Journal of chemical ecology 17 (1991), S. 2469-2480 
    ISSN: 1573-1561
    Keywords: Coleoptera ; Nitidulidae ; Glischrochilus quadrisignatus ; Glischrochilus fasciatus ; field traps ; volatile attractants ; host volatiles
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Seven volatile compounds identified from the headspace of whole wheat bread dough were investigated for their role in attractingGlischrochilus quadrisignatus andG. fasciatus in the field. Traps baited with either whole wheat bread dough or a synthetic seven-component bread dough odor caught similar numbers of these beetles, suggesting that the seven-compound combination could simulate the behavioral effect of bread dough. A series of trials using traps baited with various combinations of these chemicals showed that five compounds were significantly active in attractingG. quadrisignatus andG. fasciatus, but not all were essential for maximum response. The simplest blend eliciting a level of response comparable to the seven-component combination included ethyl acetate, acetaldehyde, ethanol, and racemic 2-methylbutanol, of which ethyl acetate, ethanol, and acetaldehyde were essential and 2-methylbutanol was replaceable with 2-methylpropanol forG. quadrisignatus attraction. Ethyl acetate and ethanol were essential for comparable attraction ofG. fasciatus. The chemical mediation of food finding in G.quadrisignatus andG. fasciatus is discussed in the context of volatile blends characterized for other nitidulid species.
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  • 26
    ISSN: 1573-1561
    Keywords: Dendroctonus frontalis ; Coleoptera ; Scolytidae ; Dinotiscus dendroctoni ; Hymenoptera ; Pteromalidae ; parasitoid ; kairomone ; electroan-tennogram
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In two studies using the electroantennogram (EAG) technique, bark beetle- and tree-produced semiochemicals were presented toDinotiscus dendroctoni (Ashmead), a larval parasitoid ofDendroctonus frontalis Zimm. In the first study, 20 test compounds and a standard mixture of oxygenated monoterpenes were presented individually at one concentration to the parasitoids. In the second study, the nine compounds that elicited the greatest EAGs in study 1 were then tested as serial dilutions of 10 to 0.0001μg/ul. The individual compounds did not elicit responses greater than the standard mixture of oxygenated monoterpenes. Males and females exhibited similar dose responses, although females showed lower thresholds of response than males to frontalin, terpinen-4-ol,E,Z-chalcogran, andexo-brevicomin. In both studies, pino-/isopinocamphone elicited the greatest responses at high concentrations. Tests of different ratios of the camphone mixture indicated that pinocamphone elicited the greatest response. Most of the test compounds elicited similar responses which suggests that several of the compounds may be used together byD. dendroctoni in habitat and/or host community location.
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    The European physical journal 19 (1991), S. 203-206 
    ISSN: 1434-6079
    Keywords: 36.40 ; 79.20
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    Topics: Physics
    Notes: Abstract Direct production of cations and anions of metal clusters of Sb and Bi by laser evaporation in a vacuum has been studied. Bulk sample substrates are irradiated by 1064, 532 and 355 nm beams at variable intensity, and the ions produced are accelerated and identified by time-of-flight mass spectrometry. At 1064 nm, the cation distributions show that Sb 3 + and Bi 3 + are the most abundant species, while the monomer and dimer cations are almost non-existent. The anion spectra indicate very low yields of Sb− and Bi− with dominant dimer anion species. These patterns persist with laser power variation within the stable operation domain. With lower incident laser wavelength, the mass distributions are modified, favouring the production of the light cluster ions. In no circumstances were Sb and Bi ions withn〉5 observed. Many of the observed phenomena can be explained if one assumes that for these elements, clusters withn〈6 are formed on the substrate surface. Cluster ions are produced via a prompt desorption process, and are subjected to photon induced reactions due to the same incident laser beam. However, more detailed investigation of the desorption properties will be necessary to confirm such a desorption mechanism.
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    The European physical journal 19 (1991), S. 333-335 
    ISSN: 1434-6079
    Keywords: 36.40 ; 61.16.D ; 82.65.F
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    Topics: Physics
    Notes: Abstract Gold particles deposited on graphite in vacuum have been studied by STM observation in air. Liquid-like coalescence between small gold-particles has been observed near room temperature. Preparation of small particles in vacuum is discussed. Small particles are formed in nucleation process if the degree of coalescence of particles is reduced. Over 400 Au particles of 5 nm in diameters with a narrow size-distribution with FWHM 2 nm and a high density of 3×1012/cm2 is prepared by evaporating gold in a vacuum of about 2×10−5 Torr and at the substrate (HOPG) temperature of 20°C.
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    The European physical journal 19 (1991), S. 347-351 
    ISSN: 1434-6079
    Keywords: 82.65.Jv ; 36.40
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    Topics: Physics
    Notes: Abstract Palladium clusters with a low size dispersion and a single crystallographic shape have been obtained by epitaxial growth on (100) MgO. The isothermal adsorption — desorption kinetics of CO is obtained by a molecular beam method allowing the direct determination of the global adsorption probability and of the mean life time of CO molecules on the clusters. Three main results are deduced from these measurements: — an increase of the adsorption rate of CO on the clusters by the capture of CO molecules physisorbed on the substrate, — a faster desorption rate from (100) than from (111) facets at high coverage, — an increase of the adsorption energy for clusters smaller than 3 nm.
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    The European physical journal 19 (1991), S. 423-425 
    ISSN: 1434-6079
    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract The structural stability and energetics of carbon, silicon, and germanium microclusters containing 3−7 atoms have been investigated by using a recently developed empirical many-body potential energy function (PEF), which comprises two- and three-body atomic interactions. The PEF satisfies both bulk cohesive energy per atom and bulk stability exactly. It has been found that the most stable C3−4 microclusters are linear withD ∞h symmetry but C5−7 microclusters are planar withD nh symmetry. Silicon and germanium microclusters show similar structural stability. TheX n (X=Si, Ge;n=3−7) microclusters are found to be most stable in the following forms:X 3 is triangular withD 3h symmetry,X 4 is tetragonal withT d symmetry,X 5 is square pyramidal withD 4h symmetry,X 6 is bipyramidal square withO h symmetry, and finallyX 7 is square pyramidal having two atoms underneath withD 2h symmetry.
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    The European physical journal 19 (1991), S. 431-433 
    ISSN: 1434-6079
    Keywords: 35.20 ; 36.40 ; 82.30Q
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    Topics: Physics
    Notes: Abstract Recent theoretical studies proved some of the small carbon clusters C n (n≈1−10) are represented by several isomeric structures. Evaluation of the isomer relative stabilities is necessary for comparison of theoretical data with observation, this being exemplified by the C4 and C6 cases. For the former cluster a new energy estimation has been suggested based on the isomerism reasoning. Relative-stability evaluation for clusters of different dimensions is discussed on the C60/C70 system, pointing out a strong pressure-dependency of the picture. The scheme is matched to the recent observations of Bethune and Meijer.
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    The European physical journal 21 (1991), S. 271-279 
    ISSN: 1434-6079
    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract The Hückel model is used to study the electronic structure of monovalent metal clusters. In an fcc cluster the Hückel model gives an estimate to the electronic structure of a free electron cluster. It is shown that the surface faceting of the fcc cluster can destroy the electronic shell structure already when the cluster has about 100 electrons. In the Hückel model the icosahedral structure has smaller total energy than the fcc structures, from which the Wulff construction has the smallest energy already when the cluster has 600 atoms.
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    The European physical journal 21 (1991), S. 285-288 
    ISSN: 1434-6079
    Keywords: 36.40 ; 35.20
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    Topics: Physics
    Notes: Abstract Metal clusters have been produced using a laser evaporation source. A Nd-YAG laser beam focused onto a solid silver rod was used to evaporate the material, which was then cooled to form clusters with the help of a pulsed high pressure He beam. TOF mass spectra of these clusters reveal a strong occurrence of small and medium sized clusters (n〈100). Clusters were also deposited onto grid supported thin layers of carbon-films which were investigated by transmission electron microscopy. Very high resolution pictures of these grids were used to analyze the size distribution and the structure of the deposited clusters. The diffraction pattern caused by crystalline structure of the clusters reveals 3-and 5-fold symmetries as well asfcc bulk structure. This can be explained in terms of icosahedron and cuboctahedron type clusters deposited on the surface of the carbon layer. There is strong evidence that part of these cluster geometries had already been formed before the depostion process. The non-linear dependence of the cluster size and the cluster density on the generating conditions is discussed. Therefore the samples were observed in HREM in the stable DEEKO 100 microscope of the Fritz-Haber-Institut operating at 100 KV with the spherical aberrationc S =0.5 mm. The quality of the pictures was improved by using the conditions of minimum phase contrast hollow cone illumination. This procedure led to a minimum of phase contrast artefacts. Among the well-crystallized particles were a great amount of five- and three-fold symmetries, icosahedra and cuboctahedra respectively. The largest clusters with five- and three-fold symmetries have been found with diameters of 7 nm; the smallest particles displaying the same undistorted symmetries were of about 2 mm. Even smaller ones with strong distortions could be observed although their classification is difficult. The quality of the images was improved by applying Fourier filtering techniques.
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    The European physical journal 19 (1991), S. 199-201 
    ISSN: 1434-6079
    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract Neutral lead cluster beams with ultra-narrow size distribution were produced by neutralization of mass-selected lead cluster ions, Pb n + withn≤12, in sodium vapor under near-resonant conditions. Absolute charge exchange cross sections were measured as a function of cluster size and are on the order of 40 Å2 forn≥4. Possible fragmentation of the clusters associated with charge transfer was examined by translational spectroscopy. No indication of fragmentation was found.
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    The European physical journal 19 (1991), S. 409-412 
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    Keywords: 36.40
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    Notes: Abstract Large even-numbered carbon clusters in the size range from 100 to 600 atoms (giant fullerenes) were generated by laser vaporization and directly injected as positive ions via a supersonic beam into the magnetic trap of an ion cyclotron resonance apparatus. Intense laser excitation of the magnetically levitated fullerenes at 4.0 eV was found to result in production of multiply charged fragments in the trap. Details of the time scale and size dependence of this process suggest it is due to thermionic emission from the superheated gas phase clusters.
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  • 36
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    The European physical journal 19 (1991), S. 435-438 
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    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract The electronic spectrum of C60 is calculated using quantum mechanical methods. The first allowed transition in C60 is calculated at an energy of 3.5 eV and with an oscillator strength of 0.09. Several transitions are found at higher energies with comparatively strong oscillator strengths, the strongest one being at 5.78 eV (λ=214 nm). The calculated energy level diagram of C60 is also used to predict wavelengths for transitions in C 60 + and C 60 − . A comparison is made with some recently observed diffuse interstellar bands at 1180 nm and 1320 nm, which have been speculated to originate from C 60 + .
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    The European physical journal 18 (1991), S. 181-188 
    ISSN: 1434-6079
    Keywords: 36.40 ; 82.50.F
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    Topics: Physics
    Notes: Abstract The infrared photodissociation spectra of C2H4 and CH3OH dimers are measured for different internal excitation energies ΔE. The dimers are size-selected in a scattering process with He and the internal energy is varied by using (1) different collision energies, (2) different scattering angles and (3) by measuring the complete energy loss spectra with and without laser radiation by time-of-flight analysis of the scattered clusters. For (CH3OH)2 the width Γ of the spectrum increases strongly with ΔE, while the cross section at the maximum is constant, a normal behaviour for an inhomogeneously broadened system. For (C2H4)2 Γ is nearly constant after a sort of threshold and the cross section increases with increasing ΔE. These results are explained by hot band excitation and the coupling to the darkv 10-mode.
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    The European physical journal 18 (1991), S. 257-265 
    ISSN: 1434-6079
    Keywords: 33.20 ; 35.20 ; 36.40
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    Topics: Physics
    Notes: Abstract Rotationally cold Na3-molecules are formed during the adiabatic expansion of an argon beam, seeded with 5% sodium vapor. With a single mode tunable dyelaser crossing the molecular beam perpendicularly within the ion source of a mass spectrometer the Na3-molecules are excited into levels of the2 A 2-state which are then ionized by acw argon-laser. Rotational lines of the electronic2 A 2 ←X 2 B 2 transition and their hyperfine structure could be resolved using an OODR-technique. A preliminary analysis of the measured spectra is discussed and a comparison of the experimental results with ab initio calculations is presented.
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    The European physical journal 18 (1991), S. 267-280 
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    Keywords: 36.40 ; 33.80E
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    Notes: Abstract Analysis of free metal clusters studied with photoionization mass spectrometry or photoelectron spectroscopy requires theoretical predictions of the photoionization cross sections to gain a deeper physical understanding. Calculated energy-dependent photoionization cross sections of Na2–8 and K2–8 clusters are presented in this study. The ground state electronic structure of the clusters are calculated using the Local Spin Density method (LSD) which is also the starting point for the cross section calculation with the continuum multiple scattering method. A basic analysis of the photoionization process is given within the independent electron picture. Strong resonances are predicted in the UV cross sections (5–10 eV) of K3–8 but not for Na3–8, interpreted as shape resonances, i.e. quasibound states in which electrons are trapped by a potential barrier. Unfortunately experimental data are only known close to the ionization threshold and a comparison between our values and experimental data in a broad energy range is not possible.
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    The European physical journal 19 (1991), S. 31-36 
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    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract A brief survey is presented of recent simulations of small clusters, made with both ab-initio and classical approaches, with particular emphasis on the application of the Car-Parrinello method. The discussion mainly focusses on the structural properties of a variety of materials and on the effects of temperature.
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  • 41
    ISSN: 1434-6079
    Keywords: 36.40 ; 35.20.Wg ; 03.65.-w
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    Notes: Abstract Measurements of the mass abundance spectra of sodium clusters containing up to 600 atoms are presented. The clusters are produced in a seeded supersonic expansion of Ar or Kr gas, and the spectra are obtained by a time-of-flight technique. The sawtooth features in the spectra are interpreted as evidence of a regular spherical shell structure with magic numbers,N 0, scaling approximately with the cube root of the number of sodium atoms. Altogether twelve shell closings are observed,N 0=2, 8, 20, 40, 58, 92, 138, 196, 260, 344, 440 and 558. There is also a pronounced odd-even staggering all the way up toN=70. The experimentally observed intensity changes for the clusters around the magic numbers are discussed in terms of the electronic free energy,F(N), calculated at finite temperature, and the second differences of the free energy Δ2 F(N)=F(N−1)−2F(N)+F(N+1). The processes behind the non-uniform abundance distributions, and the thermodynamics of finite electron systems with non-uniform level spacings are discussed on this basis.
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  • 42
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    Keywords: 36.40 ; 31.20
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    Notes: Abstract An analytic expression for the total energy of metallic clusters composed ofN identical atoms of valencev and with net chargeQ is obtained by means of a variational solution of the Thomas-Fermi-Weizsäcker energy density functional within the spherical jellium model. The minimum energy is given as an expansion in decreasing powers of the cluster radiusR=r s Z 1/3, withZ=vN andr s the radius per electron of the bulk metal. The coefficients are obtained as functions ofr s . Terms of volume (R 3), surface (R 2), curvature (R), constant (R 0), (1/R) and (1/R 2) are clearly separated in the formula, as well as the different contributions (kinetic, coulombic and exchange-correlation) to each of them. The asymptotic values (R→∞) for the work functions,W(r s ), and surface energies σ(r s ), are compared to analogous semiclassical and Kohn-Sham calculations of jellium-like surfaces and to the experimental values. The size dependent behaviour of chemical potentials, μ(R), electron affinities,AF(R), and ionization potentials,IP(R), are easily obtained for any kind of metallic clusters. In particular we discuss the Coulomb and quantum corrections to the coefficients β, δ in the asymptotic formulae:IP≃W+β/R andAF≃W+δ/R.
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    The European physical journal 19 (1991), S. 77-79 
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    Keywords: 34.80G ; 36.40 ; 35.20V
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    Notes: Abstract The previously measured relative cross section function for electron impact ionization (EII) of neutral Ag2 has now been calibrated quantitatively by combining the electron impact ionization with in situ non resonant two photon ionization (NR2PI). By comparing the NR2PI saturation intensities measured for Ag 2 + and Ag+ with the corresponding EII intensities, the ratio between the electron impact ionization cross sections (EIICS) of neutral Ag2 and Ag was determined to be σAg2/σAg=1.53 for an electron energy of 46 eV. This result agrees well with the geometricn 2/3-rule $$(\sigma X_n \sim n^{2/3} )$$ commonly proposed for the dependence of the EIICS of clustersX n on the cluster sizen.
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    The European physical journal 19 (1991), S. 85-87 
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    Keywords: 36.40 ; 78.40-q
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    Notes: Abstract The optical absorption spectrum around the surface plasmon peak is presented for K 21 + . Hot, charged potassium clusters are produced by an adapted liquid metal ion source. The plasmon is found to be slightly red shifted from and distinctly broader than the one reported in an experiment on colder clusters by Bréchignac et al. [3]. Mechanisms responsible for the temperature dependence of the width and position of the surface plasmon in small metal clusters are discussed.
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    The European physical journal 19 (1991), S. 93-96 
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    Keywords: 36.40 ; 71.45.G
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    Notes: Abstract The usual spherical jellium model of alkaline clusters is generalized to allow for a finite surface thickness in the positive background distribution. Static (relative stability, ionization potentials) and response properties have been calculated and the results show a better agreement with experiments.
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    The European physical journal 19 (1991), S. 97-99 
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    Keywords: 34.80.B ; 36.40
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    Notes: Abstract The following calculations are based on the local density approximation potential (LDA) of W. Ekardt for the spherical jellium-background model (SJBM). Taking into account the smooth shape of the potential, the WKB approximation was used to calculate the energy and angular dependence of the electron scattering cross-sections fo rsmall Na clusters. The number of phase shifts needed to describe the scattering in the range of energies 〈4.5 eV increases with the size of cluster. The calculated elastic electron scattering cross-sections for the Na clusters, corresponding to the shell closings (8, 20, 40), are exhibiting a pronounced peak structure, correlated with resonance states. The computed peaks of the angular dependences of the cross-sections on energy are shifted to small angles with increasing the cluster size. The absence of fragmentation at these small electron energies presents a challenge for the experimentalists.
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    The European physical journal 19 (1991), S. 129-131 
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    Keywords: 36.40 ; 79.70 ; 35.20X
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    Notes: Abstract Cluster ions of alloys (Li-Na, Li-Mg) have been produced by a liquid metal ion source (LMIS), and analyzed by mass spectrometry. For the Li-Na system, bimetallic clusters with various compositions were formed, and dominant bimetallic species were Na2Li+, NaLi+, NaLi 2 + and NaLi 8 + with this sequence of ion intensity. These clusters are systems containing 2 or 8 valence electrons except for NaLi+. For the Li-Mg, observed bimetallic clusters were limited to only three species (MgLi+, MgLi 2 + and Mg2Li+), but unexpectedly small multiply charged homonuclear clusters, Mg 2 2+ and Mg 3 2+ , were observed.
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    The European physical journal 19 (1991), S. 181-184 
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    Keywords: 05.70 ; 07.75 ; 36.40
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    Notes: Abstract The vapor over sodium-tellurium alloys was investigated using Knudsen effusion mass spectrometry. The stoichiometries of the molecules in the gas phase are compared with the stoichiometries of those appearing in liquid ammonia. Enthalpies of formation for the gaseous molecules are obtained using van't Hoff plots and third law evaluations.
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    The European physical journal 19 (1991), S. 189-190 
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    Keywords: 36.40 ; 35.20X ; 79.20X
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    Notes: Abstract Manganese cluster ions Mn k + (k≲60) have been produced by 7 keV Xe ion bombardment and analyzed by a double-focusing mass spectrometer. Discontinuous variations of intensity are found atk=5, 14, 16, 29, 34, 45 and 54. Most of these magic numbers coincide with or differ by only one from those observed in Ar k + . The similarity in magic numbers between Mn k + and Ar k + indicates that the bonding nature in the charged Mn clusters is similar to that in the charged Ar clusters; The polarization force between a positive ion in the center of a cluster and surrounding neutral atoms is dominant binding force.
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  • 50
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    Notes: Abstract Photodetachment spectra of negative carbon clusters are reported in the size range from 5 through 20 atoms. The clusters were prepared in a supersonic beam by laser vaporization and 2nd (2.3 eV) and 3rd (3.5 eV) harmonics of Nd-YAG laser were used for photodetachment. The resultant data indicate that carbon negative cluster ions in the 10–20 range take the forms of both linear chain and cyclic ring under a certain condition.
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  • 51
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    The European physical journal 19 (1991), S. 447-449 
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    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract The hydrogen uptake for small carbon clusters C4 to C22 has been studied at high hydrogen pressure. This study indicate that both chain and ring structures exist in parallel.
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  • 52
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    The European physical journal 19 (1991), S. 443-446 
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    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract Structural properties of 3d carbon clusters were calculated employing recently developed model potential energy functions for carbon. Primarily, spherical shell structures were included in the present investigation. Configurations corresponding to local energy minima were calculated for various shells of an icosahedron containing different number of C atoms. For C60, the two low-lying isomers, the buckminsterfullerene and truncated dodecahedron, were found to be almost isoenergetic. It was also found that fully relaxed structures of C90 and C120 have energies very comparable to that of C60. Furthermore, a systematic analysis carried out in this study for carbon clusters with varying dimensionalities, revealed an interesting relationship between the bond lengths and the distribution of bond angles. In all cases, shorter bond distances were found to be associated with larger bond angles.
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  • 53
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    The European physical journal 20 (1991), S. 35-38 
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    Keywords: 36.40 ; 34.80 ; 71.35
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    Topics: Physics
    Notes: Abstract A method to measure electron energy loss spectra (EELS) of clusters with a high resolution (30 meV) has been developed and has been applied to some van der Waals clusters (Ar n , Kr n ). Structures have been found which relate to the excitation of atoms on the surface and inside the cluster. An influence of the cluster size on the spectra has been observed.
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  • 54
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    The European physical journal 20 (1991), S. 39-42 
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    Keywords: 36.40 ; 71.90 ; 78.40
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    Topics: Physics
    Notes: Abstract Absorption spectra of Ar clusters containing between 10 and 106 atoms are dominated by strong transitions into bulk and surface states. The intensity variation of bulk and surface excitations is analyzed within a model, which divides the cluster into a surface layer and into an interior part. The thickness of the surface layer is determined by the intensity ratio of bulk and surface excitations. For then=2, 2′ excitons a reasonable value ranging between the radius of then=2 exciton and the nearest neighbour distance is obtained. In case of then=1 excitons the thickness of the surface layer is much smaller than the nearest-neighbour distance indicating that then=1 surface excitons might be interpreted as excitations of atoms on the cluster surface.
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  • 55
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    The European physical journal 20 (1991), S. 53-55 
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    Notes: Abstract An exact theory for excess electrons in clusters of rare gas atoms is limited to small sizes,n 〈 20, because of many body polarization interactions which make it necessary to solve a large system of linear equations. We present a simple dielectric screening approximation, which avoids this difficulty and which is in very good agreement with the exact calculation. This approximation can be used to examine the excitation energies of excess electrons and exciton energies in large clusters. A new atomic structure is proposed for a cluster of 12 Xe atoms, resulting in an increased binding energy for the excess electron, which is larger than the electron affinity of a cluster of 13 atoms. This might explain the relatively large abundance of Xe 12 − observed in the experiment.
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  • 56
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    The European physical journal 20 (1991), S. 111-113 
    ISSN: 1434-6079
    Keywords: 36.40 ; 61.25
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    Topics: Physics
    Notes: Abstract Qualitative similarities and differences between metal cluster and nuclear fission are discussed in terms of the liquid drop model. Points covered include the dependence onz 2/n of the relative fission rate, the critical size, and the competition between fission and evaporation.
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  • 57
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    The European physical journal 20 (1991), S. 115-118 
    ISSN: 1434-6079
    Keywords: 36.40 ; 33.80 ; 82.30
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    Topics: Physics
    Notes: Abstract One of the major problems in cluster beam experiments with uncharged clusters is to relate the detected distribution of cluster ions to the original distribution of the neutrals. Fragmentation of the clusters, differences in ionization efficiencies, and desorption of ligands for chemically reacted clusters distort the initial distribution. In this contribution the abundances of the neutral and the ionized particles will be related by rate equations in terms of phenomenological rate constants. Two approaches are chosen. In the more simple one the ionization and decay processes are fast and take place during the excitation pulse. In the second approach delayed processes are also allowed. In both cases recursion formulas are derived as analytical solutions of the coupled rate equations for the time evolution of the neutral and ionized cluster intensities. The general solutions contain a considerable number of parameters which have to be reduced by experimental conditions and observations. Applications are discussed.
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  • 58
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    The European physical journal 20 (1991), S. 153-155 
    ISSN: 1434-6079
    Keywords: 36.40 ; 33.80 ; 33.20
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    Topics: Physics
    Notes: Abstract The absolute cross section for photodissociation of Ar2N 2 + was measured as a function of wavelength in the 470–550 nm range. A structureless broad band was observed; the cross section has a maximum of ∼ 210 × 10−18 cm2 at ∼ 500 nm. The measurement of the photofragment time-of-flight spectrum shows that(1) N 2 + , Ar+ and Ar 2 + are produced in the photodissociation of Ar2N 2 + in the wavelength range studied, and that(2) the observed visible absorption band is ascribable to a parallel-type transition of Ar2N 2 + , which possibly retains a linear geometry.
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  • 59
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    The European physical journal 20 (1991), S. 147-151 
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    Keywords: 36.40 ; 71.10 ; 77.30
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    Topics: Physics
    Notes: Abstract For Ar2–29 and Ar 2–29 + clusters at 20 K in the polarization model presented here the electrodynamical dipole-dipole many-body problem is solved selfconsistently with the Monte-Carlo method (MC) at 20 K, i.e. the instantaneous dipole-dipole interaction is solved to infinite perturbation order and in cluster expansion to the order of the cluster size. The long range many-body dipole-dipole interaction is coupled to exchange interaction by a modified effective dipole polarizability. This model will be compared to the dimer model and classical MC simulation of Ar n . The resulting different magic numbers in the binding energies are discussed in this connection with different experimental techniques of cluster ionization. By the mean square cluster diameter a shape parameter is introduced and it is found that with this parameter structural form transition in cluster growth can be resolved, and surprisingly do not correlate with the magic numbers.
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    The European physical journal 20 (1991), S. 163-166 
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    Notes: Abstract Extensive molecular dynamics simulations have been done to study the evaporation of a 13-atom Lennard-Jones cluster. The survival probability and the evaporative lifetime are calculated as a function of the cluster total energy from a classical trajectory analysis. The results are interpreted in terms of the RRK theory of unimolecular dissociation. The calculation of the binding energy of the evaporated species from the evaporation rate and the average kinetic energy release is discussed.
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  • 61
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    Keywords: 36.40 ; 82.50.F
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    Notes: Abstract Infrared photodissociation spectra of (CH3NH2) n clusters were measured fromn=2 ton=6 near the monomer absorption of the C-N stretching mode at 1044 cm−1 using a cw-CO2 laser. The clusters were size-selected by scattering from a helium beam. The spectrum of cold dimers shows a red (1038 cm−1) and a blue (1048 cm−1) shifted peak which is attributed to the non-equivalent position of the C-N in the open dimer structure. The larger clusters exhibit only one peak between 1045.4 cm−1 and 1046.0 cm−1 caused by the equivalent position of the C-N in the cyclic structures of the larger clusters. Structure calculations confirm these results. Secondly, the mixed complexes C2H4-CH3COCH3 and C2H4-(CH3COCH3)2 were investigated. The dimer spectrum, measured around the monomer frequency of the out-of-plane bending mode of C2H4 at 949 cm−1, shows two peaks at 946.2 cm−1 and 961.3 cm−1. This splitting is attributed to two different isomers that are found in configuration calculations. A similar behaviour is found for the trimer.
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  • 62
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    Keywords: 36.40 ; 34.80.G
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    Notes: Abstract The hydrogen-bonded (N2H4) n clusters and the van der Waals (OCS) n clusters are size selected in a scattering experiment with a He beam up to the cluster sizen=6. By measuring the angular distributions of the scattered clusters the complete fragmentation pattern of electron impact ionization is obtained. For Hydrazine the two main fragment masses are the protonated species (N2H4) n−1H+ and with somewhat weaker intensities also the nominal ion mass (N2H4) n + . The largest intensity is observed for the monomer ion N2H 4 + to which clusters up ton=5 fragment. For carbonylsulfide, completely different results are obtained. Aside from the fragments of the OCS monomer and the van der Waals cluster fragments (OCS) 2 + and (OCS) 3 + signals at mass S 2 + , S 3 + and S2OCS+ are detected. This indicates a fast chemical reaction in the cluster according to: S + OCS → CO + S2 which occurs for clusters of sizen ≥ 2. Peaks at S 3 + and S2OCS+ are seen for the first time forn ≥ 5 according to a further reaction of S2 in the cluster.
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  • 63
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    The European physical journal 20 (1991), S. 185-187 
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    Keywords: 33.65 ; 33.80E ; 36.40
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    Topics: Physics
    Notes: Abstract The internal energy exchanges inside an inhomogeneous van der Waals cluster are investigated by means of molecular dynamic calculations. The very long time scales for relaxation of the high frequency degrees of freedom are examined within the framework of Nekhoroshev's theorem.
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  • 64
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    Notes: Abstract Stoichiometric and non-stoichiometric, positive and negative oxygen cluster ions (n up to 70) have been produced in a crossed neutral beam/electron beam ion source. The abundance and stability of the ions formed have been analyzed with a double focussing sector field mass spectrometer in a series of experiments. Positive and negative ion mass spectra observed exhibit distinct abundance anomalies, however, at different cluster sizes. Abundance maxima and minima correlate with correspondingly small and large metastable fractions of (O2) n + and (O2) n − ions, respectively. (O2) n + ions may also lose up top=(n−1) monomers by collision induced dissociation with monotonously decreasing probability with increasingp. Metastable fractions determined for (O2) n − ions produced with appr. zero eV electrons are in general larger than those for ions produced with appr. 7 eV electrons. (O2) n − ions are also observed to decay via autodetachment, with lifetimes increasing with increasing cluster size. Finally, here we were able to prove that an apparent loss of the monomer fragment O (and higher homologues) observed in the metastable time regime is due to ordinary metastable monomer evaporation in the acceleration region. Moreover, we will also present here some new data and interpretation concerning the electron attachment cross section function for O2 clusters.
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  • 65
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    The European physical journal 20 (1991), S. 89-91 
    ISSN: 1434-6079
    Keywords: 36.40 ; 34.80 ; 33.80
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    Topics: Physics
    Notes: Abstract The laser ablation of solid targets made of mixtures of simple components yields cluster ions of various composition. In this paper, positive cluster ions formed by laser ablation of metal oxide and graphite systems are reported. The formation of Me m C n + cluster ions indicate a chemical reaction in the surrounding area hit by the laser beam.
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  • 66
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    Notes: Abstract Production and stability of Ar n +* ions (withn up to 420) formed by electron impact ionization of a supersonic Ar cluster beam were investigated with a double focussing sector field mass spectrometer. The present study confirms previous magic number determinations up to the 4th icosahedral shell. A systematic study of metastable dissociations (monomer evaporation, magic number evaporation) for singly charged cluster ions as a function of cluster size, internal excitation energy and time elapsed since ion formation gives new insight into the ionization process and subsequent reactions of the ions formed. At a well-defined threshold energy ofca. 28 eV, the magic number loss mechanism occurs simultaneously with the well known single monomer evaporation process which proceeds at all energies. The new mechanism is the first known example of cluster ion metastability showing an exponential dependence on time, providing further evidence that the precursor parent cluster ion is produced in a specific energy state.
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    The European physical journal 20 (1991), S. 235-238 
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    Keywords: 36.40
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    Notes: Abstract The transition from solid-like to liquid-like behavior in Au n ,n=6, 7, 13, clusters is studied using molecular dynamics simulations. A Gupta-type potential with all-neighbour interactions is employed to incorporaten-body effects. The melting-like transition is described in terms of short-time averages of the kinetic energy per particle, root-mean-square bond length fluctuations and mean square displacements. A comparison between melting temperatures of Au n and Ni n clusters is presented.
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  • 68
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    The European physical journal 20 (1991), S. 239-242 
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    Keywords: 36.40
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    Notes: Abstract Results of molecular dynamics simulation studies of structural and dynamical properties of 12-, 13-, and 14-atom transition metal clusters are presented. The calculations are carried out using a Gupta-like potential expressed in reduced units. The transformation to absolute units involves two size-dependent parameters which effectively convert the potential into a size-dependent one. The minimum energy geometries of the clusters are obtained through the technique of simulated thermal quenching. A melting-like transition is observed as the energy of the clusters is increased. A novel element of the transition is that it may involve a premelting state.
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  • 69
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    The European physical journal 20 (1991), S. 251-253 
    ISSN: 1434-6079
    Keywords: 36.40 ; 61.14F ; 64.70K
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    Topics: Physics
    Notes: Abstract The structure of SF6 clusters produced in a free jet expansion is studied by electron diffraction methods. A solid phase transition is known to occur when clusters are warmed up by changing several experimental conditions in the expansion of a Ne + SF6 mixture. In the present study, the total stagnation pressure and the SF6 mole fraction are varied in order to understand how these parameters influence the structural state of the clusters and further to observe the phase transition for different cluster sizes. When the stagnation pressurep 0 is larger than about 10 bar, a given mole fraction results in clusters with identical structure and probably identical temperature. Whenp 0 is decreased below 10 bar, identical structures are found for lower and lower mole fractions. This structural behaviour suggests that for small clusters, containing less than about 500 molecules, the transition steps occur at temperatures lower than those observed for larger clusters. The possibility of detecting a temperature variation in the diffraction patterns of small cubic clusters is discussed.
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    The European physical journal 20 (1991), S. 255-257 
    ISSN: 1434-6079
    Keywords: 36.40 ; 61.14.F ; 64.60.Q ; 82.20.M
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    Topics: Physics
    Notes: Abstract A method has been devised to study the kinetics of phase changes in an unfamiliar regime of extreme undercooling and rate of transformation. We show how electron diffraction can monitor the time evolution of phase changes in molecular clusters condensed from the vapor in supersonic flow. Transitions taking place in microseconds are readily followed. Examples include solid state transformations as well as the freezing of liquid clusters. Aspects of the experiment making it possible to observe familiar transitions under highly unusual conditions will be discussed along with some advantages of the new technique.
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    The European physical journal 20 (1991), S. 259-261 
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    Keywords: 36.40
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    Notes: Abstract Stabilities and structural fluctuations of both neutral and charged Au55 clusters are examined and discussed in relation to recent experimental observations of small gold particles with an electron microscope. Transition probabilities between the icosahedral and cuboctahedral structures are calculated according to the transition state theory using a model potential consisting of attractive many-body, repulsive pairwise and Coulomb parts. It is shown that for a neutral cluster the cuboctahedral structure has too short life time to be observed around room temperature and that, on the other hand, for more than 6-fold multiply charged clusters, both structures have life times of the order of 0.1 s around room temperature and, therefore, the transition between them can be observed.
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  • 72
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    The European physical journal 20 (1991), S. 297-300 
    ISSN: 1434-6079
    Keywords: 33.20.K ; 36.40 ; 42.20 ; 78.40 ; 82.70
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    Topics: Physics
    Notes: Abstract Au55 cluster compounds are investigated by optical spectroscopy and TEM. The optical spectra appear to be rather structureless, neither showing a collective excitation resonance nor exhibiting distinct absorption bands known from lower nuclearity clusters. We discuss changes of the electronic properties compared to larger Au clusters affecting both, 6sp electrons and5d-6sp interband transitions, the cluster-ligand-interaction being considered as a charge transfer process. We additionally report on a low temperature instability of the cluster compound, which results in changed optical extinction spectra. A characteristic absorption feature at λ=400 nm is attributed to small, ligand-free Au cluster fragments.
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  • 73
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    Keywords: 36.40 ; 33.60 ; 33.80.E
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    Notes: Abstract The photodetachment spectra of (H2O) n =2−69/− and (NH3) n =41−1100/− have been recorded, and vertical detachment energies (VDEs) were obtained from the spectra. For both systems, the cluster anion VDEs increase smoothly with increasing sizes and most species plot linearly withn −1/3, extrapolating to a VDE (n=∞) value which is very close to the photoelectric threshold energy for the corresponding condensed phase solvated electron system. The linear extrapolation of this data to the analogous condensed phase property suggests that these cluster anions are gas phase counterparts to solvated electrons, i.e. they are embryonic forms of hydrated and ammoniated electrons which mature with increasing cluster size toward condensed phase solvated electrons.
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    The European physical journal 20 (1991), S. 377-379 
    ISSN: 1434-6079
    Keywords: 79.60 ; 71.20 ; 36.40
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    Topics: Physics
    Notes: Abstract We measured XPS and UPS spectra of gold clusters with 55 atoms, embedded in an electrically isolating phosphine matrix, and of gold-phosphine, from which the clusters were chemically derived. Compared to the spectra of bulk gold the valence band spectrum and the core level spectra of the clusters showed shifts of the peaks and the fermi level to higher binding energies. The shift of the peaks could qualitatively be interpreted by a final state effect. We succeeded in a separation of bulk and surface contributions to the core level spectra and in a reasonable quantitative analysis of the valence band spectrum of the clusters. The Au 4f core level spectrum of gold-phosphine showed two peaks at 1.5 eV higher binding energies than the corresponding peaks of the clusters.
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    The European physical journal 20 (1991), S. 387-390 
    ISSN: 1434-6079
    Keywords: 79.20 ; 73.20 ; 36.40
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    Topics: Physics
    Notes: Abstract The electronic structure of small chromium clusters deposited by evaporation onto clean polycrystalline graphite has been studied by means of Auger, X-ray Photoemission (XPS) and Electron Energy Loss (EELS) spectroscopies. The XPS results show an increase in the binding energy of both core levels and valence band reducing the cluster size. The EELS measurements show a variation of the intensity ratio of L3-to-L2 ionization core edges. We interpret this change as due to different redistribution, within the clusterd-band, of the empty states above the Fermi level. As a consequence the XPS results may also be attributed to sizeable change of the electronic structure of the small clusters.
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    The European physical journal 20 (1991), S. 391-394 
    ISSN: 1434-6079
    Keywords: 79.60 ; 36.40
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    Topics: Physics
    Notes: Abstract Silver and chromium particles in the size range 10 nm to 25 nm formed by deposition in ultra-high vacuum on graphite have been studied using synchrotron radiation. We have determined the island size by measuring the spectral dependence of the reflectivity of each sample using light in the photon energy range 35 eV to 190 eV. Comparing this measurement to a calculation of the reflectivity modified by the size-dependent extinction, determined using Mie theory, gives the average particle radius. Using this sizing technique we find that, for the growth of silver at room temperature, the average radius increases linearly with the cube root of evaporation time. Deposition with the substrate at elevated temperatures produces, for similar coverages, an increase in the average size for temperatures between 200°C and 225°C followed by a rapid decrease above 225°C. Chromium shows size effects in the photoemission spectra from the 3s and 3p core levels and the 3d valence band. With decreasing radius a decrease in the multiplet splitting of the 3s core level and a large change in the relative intensity among the 3p multiplets occurs indicating increased electron correlation as the system becomes smaller. A narrowing of the valence band also occurs which we attribute to a structural change at the surface of the particles.
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  • 77
    ISSN: 1434-6079
    Keywords: 36.40 ; 33.40. Hp ; 32.30. Bv
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    Topics: Physics
    Notes: Abstract Microwave spectroscopy in highly excited Rydberg states is proposed for structure determination of small metal cluster ions. An experimental setup for microwave optical triple resonance is developed and tested for Yb atom. Many microwave transitions are measured with the line width less than 1 MHz (HWHM).
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    The European physical journal 20 (1991), S. 425-428 
    ISSN: 1434-6079
    Keywords: 36.40 ; 61.50.C
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    Topics: Physics
    Notes: Abstract The first successful experiments to generate continuum silver cluster beams from nozzle expansions are described. A mixture Ar/Ag expands out of a conical nozzle (0.35 mm dia., 10° cone angle, length 17 mm). At 2150 K, total pressure 300 kPa, silver partial pressure 8 kPa the silver intensity measured with a rate meter 479mm away from the source is 1.8 nm/s, or 0.02 g m−2s−1. The data for the onset of clustering confirm the predictions of the scaling laws developed to compare condensation in nozzle expansions of metal vapors with that of rare gases.
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    The European physical journal 20 (1991), S. 457-459 
    ISSN: 1434-6079
    Keywords: 36.40 ; 61.14
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    Topics: Physics
    Notes: Abstract An electron diffraction apparatus is described which has been developed for use with small particle beams. The apparatus features a pulsed 100 kV electron beam and on-line parallel measurement of the diffraction pattern using linear charge coupled devices. Preliminary results on a molecular beam of small silver particles are presented.
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    The European physical journal 20 (1991), S. 465-467 
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    Keywords: 36.40
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    Topics: Physics
    Notes: Abstract Viewing cluster science as the embryology of the full-grown forms of matter we encounter in our surroundings, makes it appear to a relative newcomer as a highly dynamic discipline. Lines of attack showing marked progress or potential promise are briefly reviewed, and a sketch of the vast field of still-open problems is presented.
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    The European physical journal 21 (1991), S. 177-184 
    ISSN: 1434-6079
    Keywords: 34.50.g ; 34.70. ; 35.20.W ; 36.40
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    Topics: Physics
    Notes: Abstract Electron attachment to SO2 clusters is studied in a pulsed crossed beam apparatus, using laser-excited nf Rydberg atoms as a low energy electron source. The results are interpreted as an attachment to a dimer subcluster followed by a rapid impulsive dissociation of the nascent dimer anion. The remaining cluster anions possess a large amount of internal energy. At low principal quantum numbersn, the influence of the Rydberg ionic core leads to an important evaporation process interpreted with simple model calculations.
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    Journal of chemical ecology 17 (1991), S. 285-308 
    ISSN: 1573-1561
    Keywords: Pheromone ; aggregation ; synergism ; ester ; carboxylic acid ; alcohol ; carboxylic ester ; driedfruit beetle ; Carpophilus hemipterus ; Coleoptera ; Nitidulidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The attractiveness of representative host materials, host extracts, and individual host volatiles (primarily carboxylic acids, alcohols, and esters) toCarpophilus hemipterus (L.) (Coleoptera: Nitidulidae) adults in wind-tunnel bioassays was examined. Attractiveness of the materials was examined alone and in combination with the aggregation pheromone. Host materials and extracts were often attractive on their own, and the attractancy was synergized when they were combined with the pheromone. Propanoic and butanoic acids, methanol, 2-propanol, 1-heptanol, methyl butanoate, and propanal were among the most effective attractants relative to the pheromone, but many other compounds significantly synergized the pheromone (typically three- to four fold). Attractiveness and synergism were influenced by the carbon chain length and branching of the substitutents. Straight-chain compounds that had at least three carbon atoms were generally effective as synergists. Many branched-chain compounds were also effective synergists. In general, the degree of attractiveness and synergism could be predicted fairly well with the physicochemical steric (Es) parameter, although the lipophilicity (Pi) parameter also appeared to be useful in explaining the lower activity of short-chain substituents. Thus, many compounds that had only limited attractiveness on their own may nevertheless play and important role in synergizing the pheromone. Structure-activity studies appear to be appropriate not only for determining optimal attractants for these insects, but also for determining effective synergists for the pheromone.
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  • 83
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    Journal of chemical ecology 17 (1991), S. 757-765 
    ISSN: 1573-1561
    Keywords: Monochamus alternatus Hope ; Coleoptera ; Cerambycidae ; male ; attractant ; (+)-cis-3-pinen-2-ol ; lightwood ; pine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A monoterpene alcohol was isolated from paraquat-induced lightwood in pines and identified as (+)-cis-3-pinen-2-ol [(+)-3]. More than a certain amount of (+)-3 induced a laboratory flight response by the male cerambycid beetle,Monochamus altematus Hope, but (+)-3 stimulated no response by the female at any dose level tested. Compound (+)-3 was not detected in trunks of sound pines.
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  • 84
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    Journal of chemical ecology 17 (1991), S. 805-809 
    ISSN: 1573-1561
    Keywords: 2-Methyl-1,4-benzoquinone ; m-cresol ; Tenebriomolitor ; Coleoptera ; Tenebrionidae ; defensive glands
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The defensive secretion ofTenebrio molitor contains a mixture of 2-methyl-1,4-benzoquinone andm-cresol. The phenol had not previously been detected in the secretion, although some investigators reported presence of 2-ethyl-1,4-benzoquinone as a second component. We failed to detect the latter quinone in secretion samples from three laboratory populations ofT. molitor.
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  • 85
    ISSN: 1573-1561
    Keywords: Pheromone ; analog ; parapheromone ; behavior ; neurobiology ; olfaction ; single neuron ; electroantennogram ; boll weevil ; Anthonomus grandis ; Coleoptera ; Curculionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Competitive field tests with α-fluorinated analogs of compounds III and IV (III-α-F and IV-α-F, respectively) of the boll weevil,Anthonomus grandis Boh., aggregation pheromone showed these compounds, when combined with the other pheromone components [(±)-I and II], to be as attractive as grandlure [(+)-I, II, and III+IV]. Dose-response curves constructed from electroantennograms of male boll weevils to serial stimulus loads of III, IV, III-α-F, IV-α-F, and the corresponding acyl fluorinated analogs (III-acyl-F and IV-acyl-F) showed the α-fiuorinated analogs to be as active as the pheromone components (threshold=0.1 μg), while the acyl fluorinated analogs had a 10-100 x higher threshold (=1-10 μg). Single-neuron recordings showed that IV neurons and II neurons (Dickens, 1990) responded to IV-α-F and III-α-F, respectively, while IV-acyl-F and III-acyl-F were inactive. Since a previous study showed compounds I, II, and IV to be essential for behavioral responses in the field, it seems likely that the activity of the α-fluorinated analogs observed here is due to the stimulation of IV neurons by IV-α-F as indicated in single neuron recordings.
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  • 86
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    Journal of chemical ecology 17 (1991), S. 1145-1158 
    ISSN: 1573-1561
    Keywords: Insecta ; Coleoptera ; Scolytidae ; Ips pini ; pheromone ; ipsdienol ; seasonal variation ; bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In May,Ips pini in New York did not respond in the field to 50–98.5% (R)-(−)-ipsdienol (synthetic). In September, beetles responded strongly to 50–60% (R)-(−)-ipsdienol (synthetic). In May and June, New York beetles showed marked preference for their own males over Arizona males, which produce an average of 94.1% (R)-(−)-ipsdienol. This suggested that ipsdienol stereochemistry alone does not ensure activity and that an additional compound is necessary for attraction in May. In the second year of field tests, attraction to synthetic ipsdienol and male beetles was tested in the spring, summer, and fall. There was response only to males in the spring and mid-summer and to both males and synthetic ipsdienol in the late summer and fall, causing a significant treatment x sampling period (date) interaction. Laboratory-reared beetles were not significantly more attracted to ipsdienol than to a blank airstream in laboratory assays, while male volatiles were significantly more attractive than ipsdienol and the blank. These data demonstrate that there is one or more unknown semiochemicals necessary for pheromonal response and that the behavioral activity of synthetic ipsdienol varies seasonally.
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  • 87
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    Journal of chemical ecology 17 (1991), S. 1557-1573 
    ISSN: 1573-1561
    Keywords: Laburnum anagyroides ; Robinia pseudacacia ; Aphis cytisorum ; Homoptera ; Aphididae ; Bruchidius villosus ; Coleoptera ; Bruchidae ; Lasius niger ; Formica species ; Hymenoptera ; Formicidae ; Triaspis thoracicus ; Braconidae ; Chalcidoidea ; quinolizidine alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The quinolizidine alkaloids (QA) of golden rain,Laburnum anagyroides, and those of phytophagous insects associated with the plant, as well as of parasitoids of the latter, were analyzed by capillary GLC and GLC-MS. The alkaloid content in samples of vegetative plant parts was high at the beginning of the season, then decreased, while that of reproductive organs was high throughout flowering, pod formation, and maturation. The analyses showed that the QA of the plant passed through two higher trophic levels (herbivorous insects and their parasitoids) and that the alkaloid pattern changed little during the passage. The alkaloids were present in two phytophagous insect species associated with golden rain: the predispersal seed predator,Bruchidius villosus [5–13μg/g fresh weight (fw)], andAphis cytisorum (182–1012μg/g fw), an aphid that feeds on shoots, leaves, and inflorescences. Braconid and chalcidoid parasitoids emerging from the bruchid host also contained alkaloids (1.3–3μg/g fw), as did three foraging ant species,Lasius niger, Formica rufibarbis, andF. cunicularia (45μg/g fw), that visited the aphid colonies or honeydew-covered leaves of aphid-infested plants. The hypothesis that developing bruchid larvae and/or the plant “manipulate” QA supply to infested seeds was not supported, because QA content of leftover endosperm in seeds after bruchid development was similar to that of uninfested seeds. The frass of developing bruchid larvae was rich in QA (31μg/ g dry weight). While aphids sequestered, the bruchid larvae took up and eliminated QA with the frass without chemical transformation.
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  • 88
    ISSN: 1573-1561
    Keywords: Ips pini ; Thanasimus dubius ; Coleoptera ; Scolytidae ; Cleridae ; bark beetle ; ipsdienol ; aggregation pheromone ; kairomone ; coevolution ; mass-trapping ; intraspecific variation ; prey-predator interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The bark beetleIps pini (Say) displays variation in its response to and production of enantiomeric blends of its pheromone ipsdienol. One of the principal predators ofIps pini isThanasimus dubius (F.), which uses ipsdienol as a kairomone for prey location. During 1988 and 1989, in Wisconsin and Michigan, the response of both species to a range of enantiomeric blends of ipsdienol was investigated. Blends tested had the following ratios of the (S)-(+) to (R)-(−) enantiomers: 3%∶97%, 25%∶75%, 50%∶50%, 75%∶ 25%, and 97%∶ 3%. Either 75% (+)∶25% (−) or 50% (+)∶50% (−) ipsdienol captured the mostIps pini in both years at both sites. The 25% (+)∶75% (−) blend also caught moreIps pini than the control during both years at both sites. All blends tested were attractive toThanasimus dubius in both years at both locations. Blend preferences of both species were variable and labile at both sites. Response patterns of both species in Wisconsin were different from those in Michigan each year. Furthermore, response patterns of both species to the ipsdienol blends changed from 1988 to 1989 at both locations. A genetic component to this variation would permit predator-prey coevolution, as well as the development of resistance byIps pini to management strategies based on mass-trapping with single blends.
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  • 89
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    Journal of chemical ecology 17 (1991), S. 581-597 
    ISSN: 1573-1561
    Keywords: Coleoptera ; Cucujidae ; grain beetles ; Oryzaephilus surinamensis (L.) ; Oryzaephilus mercator (Fauvel) ; Cryptolestes ferrugineus (Stephens) ; Ahasverus advena (Waltl) ; Cathartus quadricollis (Guér.) ; fungal volatiles ; attractant semiochemicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Responses by five species of cucujid grain beetles (mixed-sex adults) to various volatiles were assessed by means of a two-choice, pitfall olfactometer. The test volatiles were short-chain alcohols and ketones known to be produced by fungi. Both racemic and chiral 1-octen-3-ols were strong attractants forCryptolestes ferrugineus (Stephens), as had been found previously forOryzaephilus surinamensis (L.),O. mercator (Fauvel), andAhasverus advena (Waltl). 3-Methylbutanol was another good attractant for these four cucujids, and it was the only test compound to whichCathartus quadricollis (Guér.) responded positively. 1-Octen-3-one, racemic 3-octanol, and 3-octanone showed various degrees of attractiveness for the former four species of cucujids.O. surinamensis was the only species of test beetle to show much positive response to 2-phenylethanol and ethanol. ForO. mercator andO. surinamensis, 3-methylbutanol enhanced positive response to their respective cucujolide aggregation pheromones.
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  • 90
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    Journal of chemical ecology 17 (1991), S. 647-661 
    ISSN: 1573-1561
    Keywords: Trypodendron lineatum ; Coleoptera ; Scolytidae ; flight behavior ; wind speed ; semiochemicals ; wind tunnel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The response of the striped ambrosia beetle,Trypodendron lineatum (Olivier) (Coleoptera: Scolytidae), to a semiochemical-baited funnel trap was studied in a wind tunnel in the first of two experiments. Wind speeds were tested over a range of 0.0–0.9 m/sec. Percent beetle capture decreased linearly with increasing wind speed within the range tested. A second experiment showed that in the presence of wind, beetles flew upwind to a semiochemical-baited substrate. In still air, they tended to fly randomly and erratically; yet in close proximity to the baited substrate, a greater proportion of the beetles were arrested in response to the chemical stimuli and landed on the substrate than when an airflow was present. These results suggest thatT. lineatum are capable of responding to semiochemicals under varied wind conditions typically present in a forest where they use wind to orient to olfactory stimuli. However, greater numbers are arrested in response to the stimuli under relatively still conditions.
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  • 91
    ISSN: 1573-1561
    Keywords: Storage pests ; aggregation pheromone ; Prostephanus truncatus ; larger grain borer ; Coleoptera ; Bostrichidae ; 1-methylethyl (2E 2-methyl-2-pentenoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Male beetles of the larger grain borer,Prostephanus truncatus Horn (Coleoptera: Bostrichidae) were shown to produce material causing an electroantennographic (EAG) response from both male and female beetles. Volatiles from mixed sex cultures were collected on Porapak Q and fractionated by liquid chromatography (LC) with gradient elution. The total volatiles and the fractions were analyzed by gas chromatography (GC) linked to EAG, and two compounds eluting in the same LC fraction elicited EAG responses from male and female beetles. These were assumed to be components of the male-produced aggregation pheromone. Amounts of these compounds obtained were very low and less than 10−3 times the amounts of the aggregation pheromone components produced by the related species,Rhyzopertha dominica, under similar conditions. The most abundant of these EAG-active compounds was identified as 1-methyiethyl (2E)-2-methyl-2-pentenoate by comparison of its GC retention times and mass spectrum with those of synthetic analogs. The synthetic compound elicited electrophysiological and behavioral responses in both male and female beetles significantly greater than those to structural analogs. This compound is attractive toP. truncatus beetles in the field, and has been given the trivial name of “trunc-call 1”.
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  • 92
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    Journal of chemical ecology 17 (1991), S. 1159-1176 
    ISSN: 1573-1561
    Keywords: Insecta ; Coleoptera ; Scolytidae ; Ips pini ; pheromone ; isolation ; identification ; bioassay ; ipsdienol ; lanierone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A new pheromone component, lanierone, (2-hydroxy-4,4,6-trimethyl-2,5-cyclohexadien-1-one) was isolated and identified from a Porapak Q collection of volatiles from maleIps pini from New York through GC fractionation, bioassay, and spectrometry. In both the laboratory and the field, synthetic lanierone, in a 1:100 ratio with synthetic ipsdienol, is as attractive as natural pheromone sources. Synthetic ipsdienol alone is not attractive in the laboratory and only weakly attractive in the field. Varying the ratio of lanierone to ipsdienol in the field from 10−4∶1 to 1∶1 in 10-fold increments resulted in an increased number of beetles trapped at the three lower ratios, but also in an increase in the proportion of males trapped. In the field, all combinations of lanierone to ipsdienol attracted proportionately fewer males than did pheromone-producing male beetles. GC and GC-MS analyses of Porapak Q-trapped volatiles revealed that lanierone is produced in an amount equal to about 0.2% of that of ipsdienol and is produced exclusively by males. The small amount of lanierone produced, together with a GC retention time similar to that of ipsdienol on a nonpolar column, probably confounded its detection in earlier studies.
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  • 93
    ISSN: 1573-1561
    Keywords: Aggregation pheromone ; field trapping ; laboratory bioassay ; Coleoptera ; Curculionidae ; Rhynchophorus palmarum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Field trapping of the American palm weevil (APW),Rhynchophorus palmarum, showed that the combination of caged male APWs and palm stem was much more attractive to APWs of both sexes than palm stem alone. Caged female APWs did not enhance the attractiveness of the palm. Caged APWs without palm stem were not attractive. Virgin laboratory-bred males were highly attractive to APWs of both sexes in a two-choice pitfall olfactometer, whereas virgin laboratory-bred females were not. Adsorbenttrapped volatiles from virgin laboratory-bred males reproduced the effect of living males, giving evidence for a male-produced aggregation pheromone in this species. Wild-mated APWs of both sexes were as responsive to the aggregation pheromone as virgin laboratory-bred APWs. This is the first record of chemical communication in this species. These results have prompted investigations into the chemical identification of the aggregation pheromone.
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  • 94
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    Journal of chemical ecology 17 (1991), S. 1273-1286 
    ISSN: 1573-1561
    Keywords: Coleoptera ; Nitidulidae ; Carpophilus lugubris ; dusky sap beetle ; host finding ; chemical attractants ; wind-tunnel bioassay ; attraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The chemical mediation of host-finding was investigated for the dusky sap beetle,Carpophilus lugubris Murray. GC-MS analysis of the headspace volatiles above whole-wheat bread dough inoculated with baker's yeast, a substrate previously determined to be an effective attractant, revealed seven major components in the following order of decreasing concentration: ethanol, acetaldehyde, 2-methylpropanol, 3-methylbutanol, propanol, 2-methylbutanol, and ethyl acetate. Solutions of these seven compounds blended so as to mimic the odor of whole-wheat bread dough elicited upwind orientation from 1.8 m in a wind tunnel byC. lugubris at a level comparable to that elicited by the bread dough. A series of bioassays investigating the role of individual components from the synthetic blend determined that all seven compounds contributed to behavioral activity; however, the simplest blend evoking attraction comparable to bread dough included acetaldehyde, ethyl acetate, 2-methylpropanol, and 3-methylbutanol. Of these compounds, acetaldehyde was essential, ethyl acetate was interchangeable with ethanol or partially replaceable with propanol, and 2-methylpropanol and 3-methylbutanol were partially replaceable with a combination of the other alcohols. Headspace volatiles above aseptic or fungus-inoculated tomato, banana, sweet corn, and strawberry were also qualitatively and quantitatively analyzed. This study suggests thatC. lugubris locates its food sources by response to variable blends of common volatile constituents of plants and fungi.
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  • 95
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    Journal of chemical ecology 17 (1991), S. 1421-1435 
    ISSN: 1573-1561
    Keywords: Interspecific mating ; Ips confusus ; Ips paraconfusus ; Coleoptera ; Scolytidae ; reproduction ; reproductive isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Host and conspecific discrimination were tested as reproductive isolating mechanisms betweenIps paraconfusus Lanier infestingPinus coulteri (Torrey) andI. confusus (Le Conte) infestingP. monophylla (Fremont). In two areas (one area largely Coulter pine and the other largely pinyon pine) where these bark beetles and hosts cooccur in southern California, we induced pheromone production in host and nonhost logs using males of each species.Ips paraconfusus females joined both heterospecific and conspecific males tunneling in both tree species in each area.Ips confusus females failed to joinI. paraconfusus males in Coulter pine, but joinedI. paraconfusus in pinyon pine. Sympatry was demonstrated when females of both sibling species joined conspecific males in their respective hosts. Males attacked all four beetlehost treatment combinations in both areas. Laboratory tests confirmed these results. Males did not displace heterospecific males from nuptial chambers in hosts, and they did not occupy a gallery in which heterospecific males produced frass. Females that left conspecific males in a host were readily accepted by heterospecific males and oviposited in a nonhost.
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  • 96
    ISSN: 1573-1561
    Keywords: Sinaibin ; glucosinolate ; resistance ; Sinapis alba ; Brassica napus ; Phyllotreta cruciferae ; Coleoptera ; Chrysomelidae ; Mamestra configurata ; Lepidoptera ; Noctuidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Sinalbin was identified as a chemical component of insect anti-xenosis and antibiosis resistance mechanisms in seedlings ofSinapis alba by DEAE-Sephadex chromatography, HPLC, treatment with sulfatase and myrosinase, various feeding tests using artificial and natural substrates, and by measuring sinalbin concentrations in cotyledons and leaves during seedling development. The effects of sinaibin on feeding were dependent upon the insect species and upon the rapidly changing profile of sinaibin concentrations in the developing seedling. The high concentrations of sinalbin found in young cotyledons (up to 20 mM) and leaves (up to 10 mM) deterred the feeding of the flea beetle,Phyllotreta cruciferae Goeze and larvae of the bertha armyworm,Mamestra configurata Walker. The protection that sinalbin confers upon the vulnerable, newly emerged seedling (and upon tiny, young leaves) appears critical for the first few days of survival ofS. alba under feeding pressure from flea beetles in the field. The lower concentrations of sinaibin found in older cotyledons and leaves (2–3 mM) offer little or no protection againstP. cruciferae and may actually stimulate the feeding of this crucifer specialist. These concentrations of sinaibin, however, are still effective in reducing the level of feeding by larvae of the more generalist feederM. configurata.
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