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  • oxidation  (64)
  • biological control  (53)
  • Springer  (117)
  • 2000-2004  (117)
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  • 2000  (117)
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  • Springer  (117)
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  • 2000-2004  (117)
  • 1980-1984
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 95 (2000), S. 105-111 
    ISSN: 1570-7458
    Keywords: biological control ; Hymenoptera ; Trichogrammatidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 2
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    Entomologia experimentalis et applicata 96 (2000), S. 185-188 
    ISSN: 1570-7458
    Keywords: Trichogramma turkestanica ; Ephestia kuehniella ; development time ; activity threshold ; biological control ; flour mills
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 3
    ISSN: 1570-7458
    Keywords: Leptomastix epona ; Pseudaphycus flavidulus ; Pseudococcus viburni ; host size ; suitability ; quality ; preference ; sex ratio ; clutch size ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five host size classes which mostly consisted of one host stage (first, second, third instar nymph, young adult and preovipositing adult) of the mealybug Pseudococcus viburni (Signoret) Fernald,1903  [Hemiptera: Pseudococcidae] were tested for susceptibility and suitability for the solitary parasitoid Leptomastix epona(Walker) Graham, 1969  and the gregarious Pseudaphycus flavidulus (Brèthes) De Santis, 1964 [both of them Hymenoptera: Encyrtidae] in no choice experiments. Hosts larger than 1  mm (third instar) were suitable for the development of the parasitoids. Choice experiments with all the host size classes offered simultaneously showed that L. epona and P. flavidulus are parasitoids of mainly larger hosts (〉1 mm, third instar nymphs) therefore the parasitoids exploit the same host range. In L. epona, a faster development and a larger size of wasps occurred in host size class 1.83–2.33 mm (young adult mealybugs) indicating a greater host quality compared to other sizes. Proportion of male offspring decreased with the host size following the host size distribution models. In P. flavidulus there was no effect of host quality (size at parasitism) on developmental time, sex ratio or parasitoid size and fecundity. Larger clutch sizes of P. flavidulus emerged from larger hosts but overall this parasitoid was able to parasitize smaller hosts (〈1 mm, second instar nymphs) compared to L. epona.Experience of oviposition for 24 h does not seem to affect host size preference or sex ratio of the offspring in L. epona. Implications of the findings for mass-rearing and single applications of the parasitoids for the purpose of a biological control programme are discussed.
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  • 4
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    Entomologia experimentalis et applicata 94 (2000), S. 141-147 
    ISSN: 1570-7458
    Keywords: aphid honeydew ; biological control ; Coccinellidae ; diet ; oviposition ; predation ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Insect predators may commit to reproduction to varying degrees depending on the nature of the prey they consume. I compared egg production by females of the aphidophagous ladybird beetle Coccinella transversalis (F.) (Coccinellidae) maintained on differing diets. As expected, females laid most eggs on a diet of aphids (pea aphids, Acyrthosiphon pisum[Harris]). Upon being switched from a diet of aphids, females laid no eggs after the first 3 days when maintained on a water solution of sucrose, and laid almost no eggs when maintained on a diet of second-instar larvae of the moth Helicoverpa armigera (Hübner). However, females laid eggs in small numbers (on average, 2.7 eggs per day) when provided both sucrose and Helicoverpa larvae. Females laid similar numbers of eggs when aphid honeydew was substituted for sucrose in combination with Helicoverpa larvae; in both cases, egg production was only 10–15% of that on a diet of aphids. The production of small numbers of eggs from consumption of non-aphid foods may enhance the ability of aphidophagous ladybirds to optimize their timing of reproduction at short-lived colonies of their preferred aphid prey.
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  • 5
    ISSN: 1570-7458
    Keywords: Aleochara bilineata ; Aleochara bipustulata ; Delia radicum ; interspecific competition ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study evaluates the efficacy of Aleochara bilineata Gyll and Aleochara bipustulata L. (Coleoptera: Staphylinidae) as biological control agents against the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae). Biological and demographic characters are documented and comparisons made between the two species. The following results were obtained: (1) The reproductive potential and longevity of A. bipustulata females are significantly higher than those of A. bilineata. These differences are correlated with the biology and ecology of the hosts of both species. (2) Under laboratory conditions the rate of increase (rm) of both staphylinids species is significantly higher than that of the pest and their major competitor Trybliographa rapae West. (Hymenoptera:Figitidae). This may indicate that A. bilineata and A. bipustulata can be effective biological control agents. (3) Aleochara bilineata appears to be the most interesting biological control agent against D. radicum, because of its higher rate of increase, higher host specificity and host acceptance, and a development time which is well synchronised with that of its host. With its higher competitive ability, a population of A. bilineata may increase even if competition occurs. However, A. bipustulata presents interesting biocontrol characteristics, but the best strategy may be only to use the potential of its natural populations.
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  • 6
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    Entomologia experimentalis et applicata 96 (2000), S. 231-237 
    ISSN: 1570-7458
    Keywords: Trybliographa rapae ; Delia radicum ; parasitoid ; host-stage ; acceptance ; host quality ; preference ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Host-stage selection by Trybliographa rapae Westwood (Hymenoptera: Figitidae) was studied in choice and no-choice experiments in the laboratory. The parasitoid was able to reproduce in first, second, and third instars of the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae), but oviposition occurred more frequently in third instars when all three developmental stages were offered simultaneously. Oviposition in third instars increased the rate of development of offspring and their body size, but did not alter sex ratio. Results are discussed in the light of predictions made by the theory of optimal host acceptance.
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  • 7
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    Entomologia experimentalis et applicata 97 (2000), S. 75-81 
    ISSN: 1570-7458
    Keywords: aphid ; biological control ; Nicholson–Bailey ; parasitoid ; population dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An increasing number of researchers are studying behaviour in the hopes of understanding population dynamics or improving biological control efforts of insect pests by natural enemies. However, it is unclear exactly how behavioural studies will improve our understanding of these population level processes. In this paper we argue that in order to understand population level processes, the problem must be approached from a population biology perspective. A comprehensive understanding of certain behaviours will provide little towards our understanding of host-natural enemy interactions. For example, using an aphid-parasitoid model, we examined the effect that a commonly studied behaviour, variance in host selection by aphid parasitoids, has on aphid-parasitoid population dynamics. Differential host selection does not qualitatively alter classic Nicholson-Bailey dynamics, but only results in quantitative differences in aphid-parasitoid population sizes. Irrespective of the degree of aphid instar preference, a large increase in the number of aphids is followed by a large increase in the number of parasitoids, decimating the aphid population. Thus, studying some behaviours, such as variance in host selection, will not contribute substantially to an understanding of aphid-parasitoid population dynamics.
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  • 8
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    Entomologia experimentalis et applicata 97 (2000), S. 167-174 
    ISSN: 1570-7458
    Keywords: foraging behaviour ; patch-time allocation ; rules-of-thumb ; biological control ; Orius ; Anthocoridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Components of search effort were determined for adult females of Orius tristicolor (White) (Hemiptera: Anthocoridae) on bean, Phaseolus vulgaris L., leaves with either western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) or twospotted spider mites, Tetranychus urticae (Koch) (Acari: Tetranychidae) as prey. In the absence of prey, females of O. tristicolor allocated significantly more search time to leaves damaged by western flower thrips than to leaves damaged by twospotted spider mites, artificially damaged leaves or undamaged leaves. In the presence of prey, search time increased with increasing amounts of leaf damage for both prey species, but was not affected by prey species. Amounts of leaf damage or type of prey did not affect giving-up-time. The proportion of predators that successfully located thrips increased with increasing amounts of thrips damage on leaves. Females of O. tristicolor appeared to follow some simple, behavioural rules-of-thumb for allocation of search effort. The presence and type of damage determined the initial effort allocated to searching a leaf. Subsequent effort was determined by successful capture of prey, regardless of species. The implications of these results for application of Orius spp. for biological control are discussed.
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  • 9
    ISSN: 1570-7458
    Keywords: Leptomastix epona ; Pseudaphycus flavidulus ; Pseudococcus viburni ; oviposition behaviour ; host size selection ; experience ; developmental refuge ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oviposition behaviour and host size selection of the solitary parasitoid Leptomastix epona(Walker) and the gregarious Pseudaphycus flavidulus(Brèthes) [both Hymenoptera: Encyrtidae] were examined on five size classes of the mealybug Pseudococcus viburni(Signoret) [Hemiptera: Pseudococcidae]. The host size classes mostly consisted of one stage (first, second, third instar nymph, young adult and preovipositing adult) and were presented together to wasps of either parasitoid species. Both parasitoid species locate the host by drumming the surface of the patch with the antennae. Leptomastix eponaseems to use mainly the antennae to examine the host but P. flavidulusmay accept or reject a host for oviposition after antennation or insertion of the ovipositor. Leptomastix eponaattempts oviposition in all the host stages from second instar nymphs but P. flavidulusincludes first instar. Both parasitoid species select mainly larger hosts (〉1 mm, third instar nymphs) to oviposit but P. flavidulusis able to parasitize more second instar nymphs compared to L. epona. Female wasps of L. eponamay host feed on small mealybugs (second and third instar nymphs) that they do not use for oviposition. Oviposition experience of either parasitoid species for 24 hours does not influence host size selection on patches with hosts of similar mixed sizes. Oviposition decisions are independent of the host sizes of the preceding ovipositions. Implications about stability of a single parasitoid – host system and the success of biological control of the mealybug were discussed in respect of the developmental refugia of the two parasitoid species. Niche overlap of the two parasitoid species was discussed with a view to giving an insight into a single or multiple introduction.
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  • 10
    ISSN: 1570-7458
    Keywords: citrus flower moth ; organic agriculture ; Citrus limon ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new method for rearing the citrus flower moth (Prays citri Mill.) (Lepidoptera, Yponomeutidae) on lemon [Citrus limon (L.) Burm.] callus is reported. In the present research callus (an undifferentiated mass of plant cells that can be grown under sterile conditions on an artificial medium in vitro) was induced from lemon stigma and style explants cultured on Murashige and Skoog (MS) medium supplemented with 500 mg l−1 malt extract, 13.3 μM 6-benzylaminopurine, and 146 mM sucrose. Also somatic embryogenesis and plant regeneration were obtained from the cultures of styles and stigmas of lemon. Adults were obtained from larvae on infested flowers collected in the field. Different oviposition substrates were used: white oval pearls (WOP), black oval pearls (BOP), rooted shoots (RS) of lemon obtained in vitro, and artificial flowers containing lemon callus (AF). Larvae were reared on lemon callus. Adults oviposited on RS, on WOP, and on AF. BOP were rejected as oviposition substrates. The flower moth reared on callus oviposited fertile eggs. In our tests P. citri completed three generations on callus or on callus plus shoots. In the latter case the larvae preferred callus and fed on shoots only after callus was completely eaten. The life cycle on callus at 23 ± 1 °C lasted about 21 days. There were significant differences between oviposition substrates for what concerns the number of eggs laid. It was observed that females generally preferred WOP (about 25 eggs/female) to AF (about 20 eggs/female) or RS (about 12 eggs/female) as oviposition substrate. Nevertheless the percentage of eggs that developed into adults was higher when AF sealed with stretched Parafilm were used (about 70% of eggs developed into adults). The method of rearing P. citri with AF was labour-saving and the feeding substrate (callus) had less tendency to become mouldy or decompose than when WOP and RS were used. Since such a diet is available for the insect all year round and callus can be produced in unlimited quantity, it could be possible to obtain a mass production of this moth.
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  • 11
    ISSN: 1570-7458
    Keywords: parasitoid ; Aenasius vexans ; Encyrtidae ; sex allocation ; sex ratio ; preference ; host size ; koinobiont ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The solitary endoparasitoid Aenasius vexans Kerrich (Hymenoptera: Encyrtidae) is used for augmentative releases against the cassava mealybug, Phenacoccus herreni Cox & Williams (Sternorrhyncha: Pseudococcidae), an important pest on cassava in South America. In light of the need for large numbers of high quality females, experiments were conducted on host stage suitability and sex allocation. In choice and no-choice experiments, individual female wasps were offered second and third instar, as well as adult, hosts. During the first five days after emergence, the wasps showed a steady increase in the number of hosts they successfully parasitised per day, but the respective secondary sex ratio for each instar remained constant. Parasitism was highest for third instar hosts in no-choice tests, while in choice tests parasitism was highest in both third instars and adults. The later the developmental stage of the host at oviposition, the faster the parasitoids developed and emerged, and for each host stage, the development time of males was shorter than for females. The sex ratio of the wasps emerging from hosts that were parasitised as second instars was strongly male-biased, while the apparently preferred later stages yielded significantly more females than males. Female and male A. vexans emerging from hosts parasitised at the third instar were significantly larger than for the other stages. This may explain the preference for the third instar as well as the female-biased sex ratio, as size is usually positively correlated with higher fitness, especially in females. The results suggest that third instar hosts are the most suitable for rearing high numbers of large females.
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  • 12
    ISSN: 1570-7458
    Keywords: Dicyphus hesperus ; Trialeurodes vaporariorum ; Tetranychus urticae ; Heteroptera ; Miridae ; tomatoes ; biological control ; zoophytophagous predators ; generalist predators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 13
    ISSN: 1570-7458
    Keywords: Hymenoptera ; Mymaridae ; Homoptera ; Cicadellidae ; biological control ; plant-insect interactions ; tri-trophic interactions ; behavioral ecology ; beet leafhopper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Searching and oviposition behavior and parasitization ability of Anagrus nigriventris Girault (Hymenoptera: Mymaridae), an egg parasitoid of beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), were examined on five host plant species of beet leafhopper: sugar beet (Beta vulgaris L.), red stem filaree (Erodium cicutarium[L.]), peppergrass (Lepidium nitidum Nuttall), desert plantain (Plantago ovata Forsskal), and London rocket (Sisymbrium irio L.). Beet leafhopper embeds its eggs in the tissues of these plant species. For each plant species, A. nigriventris behavior was examined on plants with and without beet leafhopper eggs. Experimental design was a 5 (plant species) by 2 (host eggs present/absent) factorial. Additionally within each treatment, parasitoid behavior was observed over a 22-h period at five different observation periods: t=0, 3, 6, 9, and 22 h where t=0 h represents initial exposure of the insect with the plant. The behavioral events observed were: `fast walking' (general searching), `slow walking' (intensive searching), ovipositor probing, grooming, feeding, and resting. Significant differences (α=0.05) among plant species in time spent on the plant, percentage of host eggs parasitized, and behavioral variables associated with intensive searching and oviposition all indicated that the plant species fell into two groups: `preferred' plants (sugar beet, London rocket, and peppergrass), and `unpreferred' plants (filaree and plantago). These variables also indicated that the parasitoids spent more time on, searched more, probed more, and oviposited more in plants with host eggs than plants without host eggs. Consistent effects of time (over the observation periods from t=0 to t=22 h) generally were detected only in the preferred plant species that had host eggs present. In these cases, intensive searching and probing decreased as time advanced, while variables related to general searching (`fast walking') and abandoning host egg patches (leaving the plant) tended to increase over time.
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  • 14
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    Entomologia experimentalis et applicata 96 (2000), S. 33-38 
    ISSN: 1570-7458
    Keywords: Coccinellidae ; Harmonia axyridis ; flightless mutation ; elytra ; wing ; biological control ; China
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A homozygous flightless strain, obtained by selection from a laboratory population of Harmonia axyridis Pallas (Coleoptera, Coccinellidae), has been reared under controlled conditions since 1982 after sampling in China. The adults of this flightless strain have normal elytra and wings but drop almost vertically when they attempt to fly. The origin of this mutation, whether laboratory or natural, is discussed. As the mutation does not affect the fitness of the beetles, this flightless strain can be used in biological control. Releasing flightless adults rather than larvae should provide the potential for more continuous control of aphids by both larvae and adults.
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  • 15
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    Entomologia experimentalis et applicata 97 (2000), S. 11-20 
    ISSN: 1570-7458
    Keywords: Aphidius ervi ; Macrosiphum euphorbiae ; crossing ; esterase ; colour pattern ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A European strain of Aphidius ervishall be introduced into Japan for the control of Macrosiphum euphorbiaeon greenhouse tomatoes. We compared this strain, which is originating from The Netherlands (EVP), with a native strain from Hokkaido, Northern Japan (SPR) in several characteristics. The percentage of parasitism of SPR and EVP was significantly different, when attacking three aphid species: 13% and 30% on M. euphorbiaeon tomato, 68% and 93% on Acyrthosiphon pisumon broad bean and 10% and 42% on Aulacorthum solanion sweet pepper, respectively. SPR and EVP differed morphologically (in the colouration of the petiole) and in the esterase banding patterns. Furthermore, cross mating experiments showed that SPR and EVP are partially reproductively isolated from each other. Complete reproductive isolation is evident in the one direction cross (EVP females and SPR males).
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  • 16
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    Entomologia experimentalis et applicata 97 (2000), S. 93-108 
    ISSN: 1570-7458
    Keywords: intraguild predation ; food-web dynamics ; biological control ; aphidophagous predator ; entomopathogenic fungus ; aphid ; parasitic wasp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We reviewed the literature on aphid parasitoids to determine the occurrence, nature and outcome of intraguild interactions. Intraguild interactions were described for larval, pupal and adult aphid parasitoids and by the type of natural enemy (fungus, predator, or parasitoid). They appear to be prevalent in most aphid parasitoid systems and, except for parasitoid-parasitoid interactions, they are mostly asymmetric, with aphidophagous predators and pathogens killing parasitoids. The limited experimental evidence from field studies is insufficient to provide a comprehensive pattern of the consequences of intraguild interactions for aphid parasitoid populations in general and, more specifically, for the efficacy of biological control. However, because intraguild interactions are widespread in aphid-natural enemy communities and mostly detrimental to aphid parasitoids, we conclude that intraguild interactions have a primary effect in driving fluctuations in aphid parasitoid populations. Drawing on case studies, we further argue that intraguild interactions can substantially alter the effectiveness of aphid parasitoids as biological-control agents.
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  • 17
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    Journal of applied electrochemistry 30 (2000), S. 727-731 
    ISSN: 1572-8838
    Keywords: electrosynthesis ; oxidation ; lignin ; vanillin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrochemical oxidative degradation of Kraft lignin was investigated in batch and flow cells on Pt, Au, Ni, Cu, DSA–O2 and PbO2 anodes. Production of vanillin was evaluated by means of formal kinetic analyses. Conversion and chemical yields were found to be dependent mainly on the applied current density, that is on the partial pressure of oxygen at the interface, while the nature of the electrode influenced the reaction rates.
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  • 18
    ISSN: 1572-879X
    Keywords: oxidation ; reduction of palladium catalysts ; chlorine effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pd–chloride precursor salt was used to prepare Pd/Al2O3 catalysts. TPSR measurements showed three distinct reactions for the oxidation of propane on palladium surface under excess of hydrocarbon: complete oxidation, steam reforming and propane hydrogenolysis. Propane oxidation on palladium catalysts was related to the Pd2+ sites observed on Pd/Al2O3 through infrared of adsorbed carbon monoxide. In fresh catalysts reduced by H2, the IR spectra showed the linear and bridge adsorbed CO species on the Pd0 surface. After propane reaction, a new band at 2130 cm-1 related to CO adsorption on Pd2+ species was noted. Carbon monoxide species adsorbed on Pd0 were also observed in all samples after reaction. Our results suggest surface ratios of Pd0/PdO during the propane oxidation. On the other hand, time on stream conversions of the complete oxidation of propane were affected by either the water generated during the reaction or added as a reactant at 10 vol%. The water generated by the reaction helped to eliminate chlorine residues in the form of oxychloride species leading to an increasing of the activity. However, the presence of water into the reaction mixture caused a strong decreasing of the activity. The inhibition mechanism of propane oxidation in the presence of water consisted in the dissociative adsorption of water on palladium sites with the possible formation of palladium hydroxide (Pd–OH) at the surface, diminishing the number of active surface sites. Dynamic fluctuations into the reaction conditions supported the idea that a pseudo‐equilibrium adsorption–desorption of water was reached. After water removal or increasing in the reaction temperature the equilibrium was shifted to the direction of OH–Pd decomposition. This behavior suggests that the inhibitory effect of water is a reversible phenomenon, being a function of the amount of water and the reaction temperature.
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  • 19
    ISSN: 1572-879X
    Keywords: methane ; oxidation ; aliphatic hydrocarbons ; zeolite ; recycle reactor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Conversion of methane in high yields to C4+ nonaromatic hydrocarbons was demonstrated in a recycle system. The principal components of the recycle system included an oxidative coupling reactor with a Mn/Na2WO4/SiO2 catalyst at 800°C for conversion of methane to ethylene, and a reactor with an H-ZSM-5 zeolite at 275°C for subsequent conversion of ethylene to higher hydrocarbons. Total yields of C4+ products were in the range of 60–80%, and yields of C4+ nonaromatic hydrocarbons were in the range of 50–60%.
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  • 20
    ISSN: 1572-8889
    Keywords: Telenomus ; Podisus maculiventris ; Euschistus obscurus ; Scelionidae ; kairomone ; biological control ; phoresy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The kairomonal activity of the attractant pheromone for the “spined soldier bug,” Podisus maculiventris (Hemiptera: Pentatomidae), was investigated by exposing fresh pentatomid egg masses in field traps with or without synthetic pheromone. Predominantly two parasitoids were recovered from exposed eggs of P. maculiventris and Euschistus obscurus: Telenomus podisi Ashmead (a generalist pentatomid egg parasitoid) and Telenomus calvus Johnson (a phoretic specialist on Podisus eggs) (Hymenoptera: Scelionidae). The incidences of T. podisi from P. maculiventris and E. obscurus eggs placed in pheromone-baited and nonbaited traps were not significantly different, suggesting that this oophagous wasp does not use the spined soldier bug attractant pheromone as a kairomone. However, T. calvus was reared almost exclusively from egg masses of P. maculiventris placed inside pheromone-baited traps. These results suggest that T. calvus females orient to volatile chemicals emitted by spined soldier bug males as a searching strategy to find areas likely to contain host eggs, in addition to the previously discovered strategy of using the pheromone to guide their phoretic behavior. The data also indicate that T. calvus can distinguish between the egg masses of these pentatomid hosts at close range.
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  • 21
    ISSN: 1572-9028
    Keywords: oxidation ; oxyacetoxylation ; alloy ; palladium ; bismuth ; benzylacetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Benzylacetate synthesis from toluene, acetic acid and oxygen on Pd–Bi binary catalyst was studied in the liquid phase. By incorporation of Bi with Pd, both the activity and selectivity were improved. Especially better stability was obtained with the catalyst having Pd/Bi = 3. Deactivation of the catalyst was investigated in detail by XRD, XPS, TEM, elemental analysis, EPMA and so on. Comparing the used catalyst with the fresh one, it was indicated that the main cause of deactivation was the dissolution of Pd into the reaction mixture from the most outer surface of the catalyst. By adopting proper reaction conditions to prevent the Pd dissolution, the catalyst having Pd/Bi = 3 was suggested to be used as an industrial catalyst.
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  • 22
    ISSN: 1572-9028
    Keywords: nitric oxide ; ammonia ; oxidation ; X-ray photoelectron spectroscopy ; scanning tunnelling microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The dissociative chemisorption of nitric oxide at Cu(110) has been shown to result in rapid ordering of oxygen adatoms as (2×1)O chains oriented along the 〈100〉 direction while the associated nitrogen adatoms are mainly disordered at 295 K. Surface diffusion of the N adatoms, following bond cleavage, is activated and ordering of the (2×3)N strings occurs on heating to 430 K. A number of distinct reaction pathways have been isolated during the oxidation of ammonia resulting in the formation of either chemisorbed imide or nitrogen adatoms. The latter depending on temperature, may exhibit a (2×3)N, a (3×3)N or both structures may exist simultaneously. The concentration of nitrogen in the complete (2×3)N structure has been determined to be 6.6×1014 cm-2, with only a 25% decrease in nitrogen concentration leading to the transformation to the (3×3)N structure. The oxygen atoms at a Cu(110)–O overlayer, and present at the ends of the (2×1) strings terminating in steps, show specific reactivity when exposed to ammonia at 375 K resulting in the “decoration” of the steps with imide species while the oxygens within the (2×1) strings remain unreactive.
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  • 23
    ISSN: 1572-879X
    Keywords: alkylbenzene ; toluene ; ethylbenzene ; xylene ; mesitylene ; p‐ethyltoluene ; cumene ; p‐cymene ; oxidation ; palladium ; 1,10‐phenanthroline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Only the side‐chain oxidation of alkylbenzenes (R–C6H3–R′–R″ R=H, Me, Et, Pri R′=H, Me; and R″=H, Me) by oxygen (35–50 atm, 200)C° is promoted in the presence of [Pd(phen)(OAc)2].
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    Topics in catalysis 11-12 (2000), S. 359-367 
    ISSN: 1572-9028
    Keywords: zeozyme ; encapsulated complexes ; copper acetate ; copper dimers ; enzyme mimic ; EPR of copper ; tyrosinase ; oxidation ; oxygenase ; tyrosine oxidation ; phenol oxidation ; hydroxylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxygenase mimicking activity of copper acetate dimers in the regioselective ortho-hydroxylation of L-tyrosine to L-dopa is enhanced on encapsulation in zeolite Y. The structure and magnetic properties of the catalytic active site were characterized by EPR spectroscopy. The spectra of this “zeozyme” reveal the presence of (1) copper acetate dimers in the supercages and (2) isolated Cu(II) ions in the sodalite cages of the zeolite. There are significant differences in the EPR spectra of the “neat” and encapsulated complexes: on encapsulation in zeolite, the Cu–Cu exchange coupling constant, −, increases to 310 from 259 cm−1 for the “neat” complex (i.e., by about 19.7%). Simultaneously the Cu–Cu separation in the dimer, estimated indirectly from the exchange coupling constant, shortens to 2.40 Å in the encapsulated state from 2.64 Å in the “neat” complex. There is, hence, a relatively greater overlap of the metal orbitals of the dimer copper atoms inside the restricted confines of the zeolite cages. The consequent, enhanced, trans axial lability of the phenolate and dioxygen ligands promotes the catalytic oxygenase activity of copper acetate dimers on encapsulation in zeolites. A causal relationship between changes in the structural features of an active site on encapsulation in the zeolite and the corresponding catalytic activity has, thus, been established.
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  • 25
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    Catalysis letters 64 (2000), S. 113-118 
    ISSN: 1572-879X
    Keywords: X‐ray photoelectron spectroscopy (XPS) ; scanning electron microscopy (SEM) ; silver ; oxidation ; surface chemical reaction ; NO ; NO x
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The behavior of a AgNO3/Ag2O/Ag “sandwich” upon heating in vacuum was studied by in situ X‐ray photoelectron spectroscopy (XPS) and ex situ scanning electron microscopy (SEM). The AgNO3/Ag2O/Ag “sandwich” was prepared by exposure of a silver foil to a NO : O2 mixture. The upper layer of the “sandwich” consists of AgNO3 crystals of a mean size between 0.1 and 0.4 μm. Heating at 550 K in vacuum results in melting of the AgNO3 crystals. A liquid film of AgNO3, readily wetting the silver, covers the surface. Cooling below the melting point of AgNO3 leads to the agglomeration of silver nitrate to long islands with a size reaching a few tens of micrometers (μm). The possible effects of AgNO3 liquid‐phase formation on surface processes are discussed.
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  • 26
    ISSN: 1572-879X
    Keywords: chlorinated hydrocarbons ; chromia ; titania ; alumina ; CVOCs ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation of perchloroethylene (PCE) was investigated over chromium oxide catalysts supported on TiO2, Al2O3, SiO2, SiO2–Al2O3 and activated carbon. The phase of chromium oxide on the catalyst surface is critical for the oxidation of PCE. The catalytic activity of PCE removal enhances as the formation of Cr(VI) species on the catalyst surface increases. The surface area and the type of the catalyst supports were also essential for high performance in the PCE oxidation. In addition, the structure of Cr(VI) on the catalyst surface also plays an important role for the decomposition of PCE. The polymerized Cr(VI) mainly formed by the interaction of metals with the support is the active reaction site for the present reaction system. CrOx/TiO2 reveals the strongest PCE removal activity among the catalysts examined in the present study.
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  • 27
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    Integrated pest management reviews 5 (2000), S. 57-66 
    ISSN: 1572-9745
    Keywords: Azadirachta indica ; biological control ; biopesticides ; integrated pest management ; neem ; nematode control ; nematicides ; plant-parasitic nematodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant products are receiving greater attention as prophylactics against several species of plant-parasitic nematodes. Numerous experiments have shown the potential nematicidal value of plant parts and their by-products when incorporated into soil or when the plants themselves are interplanted as seedlings among crop plants. Various products (oils, cakes, extracts, etc.) prepared from the leaves and seeds of the neem plant (Azadirachta indica A. Juss) (Family Meliaceae) have been reported as effective protectants against nematode pests when used as root-dips and seed treatments. Nemato-toxic compounds of the neem plant, especially the azadirachtins, are released through volatilization, exudation, leaching and decomposition. The modes of action of these compounds are complex, and a number of mechanisms in relation to nematode management are yet to be fully explored. This review critically assesses the potential of these products in the management of nematodes in tropical agriculture.
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  • 28
    ISSN: 1572-9745
    Keywords: biological control ; parasitoid guilds ; diversity ; distribution ; taxonomic status ; parasitoids ; Tephritidae ; Braconidae ; Figitidae ; Diapriidae ; Eulophidae ; Pteromalidae ; Anastrepha ; Rhagoletis ; Ceratitis ; Toxotrypana ; Rhagoletotrypeta ; Zonosemata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.
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  • 29
    ISSN: 1572-9745
    Keywords: biological control ; Maconellicoccus hirsutus ; Pseudococcidae ; mealybug ; Anagyrus kamali ; Cryptolaemus montrouzieri
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The hibiscus mealybug, Maconellicoccus hirsutus Green, was first reported in the Caribbean in 1994 in Grenada. This was the first record of the insect as a major pest in the New World. By the beginning of 2001, the pest had spread to over 25 territories from Guyana and Venezuela in the South to Bahamas in the North. The pest has also extended its distribution to Central America (Belize) and North America (California, USA). Early attempts to control the pest using pesticides resulted in failure and a classical biological control approach was adopted. Several exotic natural enemies were introduced but control was attributed to Anagyrus kamali Moursi and Cryptolaemus montrouzieri Mulsant. In all countries where biological control was implemented, this resulted in success. This paper reviews the remarkable success story. Information is provided on the distribution and factors leading to rapid spread of the pest, its pest status and resultant economic losses, and implementation of the biological control effort.
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    Journal of thermal analysis and calorimetry 61 (2000), S. 181-189 
    ISSN: 1572-8943
    Keywords: characteristic temperatures ; concentrates ; DTA ; DTG ; oxidation ; sulphides ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation of metal sulphides and sulphide concentrates was studied by means of DTA, TG and DTG curves. The behaviour of ZnS, CdS, GaS, Tl2S, Sb2S3 and Sb2S5 during thermal treatment in an oxidizing medium was investigated. The properties of these sulphides were compared and conclusions were drawn about their probable oxidation reactions and the kind of end-products obtained. The characteristic temperatures of the studied sulphides were determined on the basis of curves (DTA). The values obtained were used to compare the behaviour of the sulphides during the oxidation process in a fluid bed. The results can be used to improve the technological and economic indices in the industrial production of zinc.
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    Journal of nanoparticle research 2 (2000), S. 315-319 
    ISSN: 1572-896X
    Keywords: nanostructure ; silicon ; oxidation ; CNT tip ; ion trap ; research management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract Joint Research Center for Atom Technology (JRCAT) and its Atom Technology Project are described. The project covers a wide range of research subjects; manipulation of atoms and molecules, formation of nanostructures of semiconductors, spin electronics and first-principles calculation of dynamic processes of atoms and molecules on solid-state surfaces. Several recent achievements on nanotechnology and nanoscience are roughly sketched.
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    Journal of thermal analysis and calorimetry 62 (2000), S. 575-578 
    ISSN: 1572-8943
    Keywords: active metal ; high-dispersed iron powder ; oxidation ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two oxidation stages of electrolytic ultradispersed iron powder at the temperature range of 90–450°C have been stated. The contribution of increasing mass and evolving heat at the first oxidation stage due to changing Fe0 into Fe2O3 in the total oxidation effect is predominant. The thermal method of active metal determination in electrolytic iron powders has been developed. The coarse-grained reduced iron powder was not oxidized completely just to 900°C because of local sintering of big iron particles as a result of evolving heat at oxidation of high-dispersed iron particles.
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    Journal of thermal analysis and calorimetry 63 (2000), S. 507-515 
    ISSN: 1572-8943
    Keywords: boron carbide ; kinetic modelling ; oxidation ; water vapour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation behaviour of a B4C based material was investigated in a dry atmosphere O2(20 vol.%)-CO2(5 vol.%)-He and also in the presence of moisture H2O (2.3 vol%) as boron oxide is very sensitive to water vapour. The mass changes of samples consisting of a chemical vapour deposit of B4C on silicon nitride substrates were continuously monitored in the range 500–1000°C during isothermal experiments of 20 h. The stability of boron oxide formed by oxidation of B4C was also studied in dry and wet atmospheres to explain the kinetic curves. In both atmospheres, oxidation is diffusion controlled at 700 and 800°C and enhanced by water vapour. At 900°C and higher temperatures, boron oxide volatilisation and consumption by reaction with water vapour modifies the properties of the oxide film and the material is no more protected. At 600°C, B4C oxidation is weak but the process remains diffusion controlled in dry conditions as boron oxide volatilisation is negligible. However, in the presence of water vapour, B2O3 consumption rate is significant and mass losses corresponding to this consumption and to the combustion of the excess carbon are observed.
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  • 34
    ISSN: 1573-4889
    Keywords: ion implantation ; oxidation ; thermal ; stainless steel ; ion-beam analysis ; aluminum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract AISI-321 steel samples were implanted with Al ions (implantation-energy:40 keV; dose: 2×1017 ions/cm2). Thermal oxidationof the samples was performed at 450, 550, 600, and 650°C for periodsvarying from 1 to 6 days in air and in a corrosive CO2-containingenvironment. Nuclear Reaction Analysis (NRA) and Rutherford BackscatteringSpectrometry (RBS) were used to investigate the oxidized samples. Asignificant improvement of the oxidation resistance of the implantedmaterial in comparison to the nonimplanted material was observed. Thisespecially applies for samples oxidized at high temperatures. The aluminumdepth distribution determined by NRA [using the resonance at 992 keV of the27Al(p, γ )28Si nuclear reaction] and RBS,indicated no variation of the Al profile in the temperature region450–600°C, whereas at 650°C a slight Al diffusion wasobserved. Scanning electron microscopy (SEM–EDS) was applied to studythe surface morphology and the constitution of the oxide scale formed, aswell as to explain the influence of Al implantation on the oxidation behaviorof AISI-321 austenitic stainless steel.
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    Oxidation of metals 53 (2000), S. 467-479 
    ISSN: 1573-4889
    Keywords: Ni–5Cr–5Al ; oxidation ; magnetron sputtering ; nanocrystalline coating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A NiO-forming Ni–5Cr–5Al (at.%) alloy has been developed anddeposited as a sputtered nanocrystalline coating. The oxide formation andoxidation behavior of this coating have been studied at 1000°C inair. The oxidation rate markedly decreased with time and the oxidationkinetics obeyed the fourth power law. Complex oxide scales, consisting ofNiO, NiAl2O4 and α-Al2O3,were formed during 200 hr oxidation. The outer oxide layer consisted of NiOand NiAl2O4 and an inner oxide layer ofα-Al2O3. The sputtered Ni–5Cr–5Alnanocrystalline coating showed good oxidation resistance due to theformation of an α-Al2O3 inner layer andexcellent adhesion of the complex oxide scales.
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  • 36
    ISSN: 1573-4889
    Keywords: ion plating ; steel ; TiAlN coating ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract To improve the high-temperature oxidation resistance of STD61 steels used ashot dies or cutting tools, Ti0.3Al0.2N0.5films were deposited on STD61 steel substrates by arc-ion plating. Thedeposited film consisted of Ti3Al2N2 andTi2N phases. The oxidation characteristics were studied attemperatures ranging from 700 to 900°C in air. The deposited STD61steels displayed excellent oxidation resistance up to 800°C, butexhibited large weight gains and breakaway oxidation at 900°C. Theoxidation products were primarily Fe2O3, TiO, TiO2,and α-Al2O3, the relative amount of each oxidebeing dependent on the oxidation condition. Among various oxides, TiO2and α-Al2O3 were the major oxides at 800°Cfor at least up to 16 hr. However, at a higher temperature or a longeroxidation period, the significant outward diffusion of iron from thesubstrate resulted in the formation of iron oxides, together with otheroxides of Ti and Al.
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    Oxidation of metals 54 (2000), S. 155-162 
    ISSN: 1573-4889
    Keywords: Ni–8Cr–3.5Al ; nanocrystallization ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Magnetron-sputter deposition was used to produce a Ni–8Cr–3.5Al(wt.%) nanocrystalline coating on substrates of the same alloy. Theoxidation behavior of the cast Ni–8Cr–3.5Al alloy and itssputtered coating were investigated at 1000°C in air. Complex,layered-oxide scales composed of Cr2O3 outer layer,mixed spinel NiAl2O4 and NiCr2O4middle layer, and α-Al2O3 inner layer were formedon the Ni–8Cr–3.5Al nanocrystalline coating during 200-hroxidation, whereas Cr2O3, with some NiCr2O4external layer with internal Al2O3, formed on the castalloy. Because of the formation of this α-Al2O3inner layer on the coating, the sputtered Ni–8Cr–3.5Al coatingshowed better oxidation resistance than the cast alloy. The effect ofnanocrystallization on oxide formation is discussed. It was indicated thatthe formation of this α-Al2O3 inner layer was closely related to therapid diffusion of Al through grain boundaries in the nanocrystallinecoating and the relatively high Cr content in Ni–8Cr–3.5Al.
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    Oxidation of metals 54 (2000), S. 189-209 
    ISSN: 1573-4889
    Keywords: oxidation ; β-FeAlCr ; coatings ; magnetron sputter-deposition ; ridge-type oxide ; Al2O3 phase transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract β-FeAl coatings containing various Cr contents of 6.5–45 wt.%were produced with a closed-field, unbalanced magnetron sputter (CFUMS)deposition technique. Cyclic oxidation tests at 1100°C in air for100 1-hr cycles and isothermal exposures at 1000°C in pure O2 for100 hr were carried out with the coatings and an as-cast FeAlspecimen. All of the coatings showed good scale-spallation resistanceduring cyclic oxidation and the coating with 6.5 wt.% Cr exhibited thelowest oxidation rates in both cyclic and isothermal oxidationexposures. After oxidation, fine-grain ridge-type oxide scales formed onthe coatings, while the oxide scale formed on the cast FeAl showed alarge quantity of θ-Al2O3 blades and large interfacial voids on thebase–alloy surface. The transformation from θ to α-Al2O3was accelerated due to the presence of Cr in the coatings. The fasttransformation considerably reduced oxidation rates, suppressed fastoutward Al diffusion for the growth of a θ-Al2O3 scale, and preventedthe formation of interfacial voids that played a major role in causing thescale spallation.
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  • 39
    ISSN: 1573-4889
    Keywords: plasma spraying ; chromium steel ; oxidation ; Fe–Cr spinel oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract During plasma spraying of metals in air, rapid-oxidation reactions occur, inmost cases. In oxidation products of Cr-rich steels, Fe–Cr spineloxide is often found as a dominant oxide phase. A thermodynamic analysisof a system composed of Fe–13%Cr alloy and water vapor or air showedthat the oxidation product in a wide range of high temperatures isFe3-wCrwO4 (w〉2). This tetragonallydistorted spinel oxide is not stable at room temperature. Water vapor andair were considered as limits of the gaseous-phase composition inatmospheric spraying by a water-stabilized plasma gun, where the compositionof the plasma plume is modified by air entrainment. The equilibriumcalculations enabled determination of the effects of temperature andgas-to-solid ratio on w. To show the existence of chromium-rich,tetragonally distorted spinel oxide experimentally, a typical productresulting from oxidation of 13%Cr–steel particles during their flightin the plasma plume was studied after rapid solidific ation. This was madepossible by trapping and quenching the flying particles in liquid nitrogenat a distance from the plasma-gun nozzle corresponding to thenozzle–substrate distance in conventional plasma spraying. The resultsobtained by X-ray diffraction, Mössbauer spectroscopy, and X-rayfluorescence analysis showed that this oxide, in which w≈2.4, constitutedthe dominant phase in the oxidation product.
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    Molecular and cellular biochemistry 206 (2000), S. 151-157 
    ISSN: 1573-4919
    Keywords: cardiac function ; diabetes ; ischemia ; oxidation ; propionyl-L-carnitine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Previous studies have shown that propionyl-L-carnitine (PLC) can exert cardiac antiischemic effects in models of diabetes. In the nonischemic diabetic rat heart, PLC improves ventricular function secondary to stimulation in the oxidation of glucose and palmitate. Whether this increase in the oxidation of these substrates can explain the beneficial effects of PLC in the ischemic reperfused diabetic rat heart has yet to be determined. Diabetes was induced in male Sprague-Dawley rats by an intravenous injection of streptozotocin (60 mg/kg). Treatment was initiated by supplementing the drinking water with propionyl-L-carnitine at the concentration of 1 g/L. After a 6-week treatment period, exogenous substrate oxidation and recovery of mechanical function following ischemia were determined in isolated working hearts. In aerobically perfused diabetic hearts, compared with those of controls, rates of glucose oxidation were lower, but those of palmitate oxidation were similar. Diabetes was also characterized by a pronounced decrease in heart function. Following treatment with by propionyl-L-carnitine, however, there was a marked increase in rates at which glucose and palmitate were oxidized by diabetic hearts and a significant improvement in heart performance. Postischemic recovery of function in diabetic hearts was also improved with PLC. This improvement in contractile function was accompanied by an increase in both glucose and palmitate oxidation. Our findings show that postischemic diabetic rat heart can be improved following chronic PLC treatment. This beneficial effect of propionyl-L-carnitine can be explained, in part, by an improvement in the oxidation of glucose and palmitate.
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    Journal of materials synthesis and processing 8 (2000), S. 359-363 
    ISSN: 1573-4870
    Keywords: Mechanical activation ; brown coal ; electrophoretic mobility ; oxidation ; humic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents a study of the influence of mechanochemical activation of coal on the process of formation and degradation of humic acids. The increasing period of mechanical activation of coal causes an increase in hydrophility, electrophoretic mobility, and of electrokinetic potential of surface layers as a result of acidic carboxyl and phenolic OH groups. The effective activation requires a short period of grinding. The increased time of activation causes the secondary processes of grain agglomeration and degradation of humic acids.
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    Oxidation of metals 53 (2000), S. 427-449 
    ISSN: 1573-4889
    Keywords: sulfidation ; carburization ; oxidation ; high-temperature corrosion ; commerical alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A sulfidation/carburization study of seven commercial heat-resistant alloyswas carried out at 900°C in a H2–25 vol.%CH4–14.8N2–4CO–0.6CO2–0.6H2Satmosphere. The equilibrium partial pressures for oxygen (O2) andsulfur (S2) were 1.1×10−22 and 4.1×10−8 atm,respectively, and the carbon activity for this system was unity. The time ofexposure was 500 hr. Relatively thick, mixed sulfide scales were formed onall of the alloys tested. In addition, internal carburization occurred inall of the alloys. Using metal loss (i.e., the reduction in samplethickness) plus internal attack (internal sulfidation plus internalcarburization) as a performance criterion, an alloy with a nominalcomposition of Ni–29 wt.% Co–28Cr–2.75Si performed thebest, showing 0.71 mm of attack. An alloy with a nominal composition ofFe–20 wt.% Ni–25Cr performed the worst, being totally consumedby the test (〉3.18 mm of attack). Alloys containing relatively highamounts of silicon (〉2.5%) showed a dramatic increase in theirsulfidation resistance compared to the other alloys containing lowersilicon contents. The amount of iron present within a given material playeda dominant role in the carburization attack that occurred, with as expected,high-iron alloys showing significant internal carburization because of ahigh solubility and diffusivity of carbon in the matrix. The importance ofthe various alloying elements with respect to sulfidation and carburizationresistance is discussed.
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  • 43
    ISSN: 1573-4889
    Keywords: oxidation ; chromia ; alumina ; thin oxide films ; reactive element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In order to study the effects on oxidation behavior of changing thecomposition of oxide scales without changing the composition of theunderlying alloys, thin films, which contained various amounts of Y2O3,Cr2O3, or Al2O3 have been deposited on Fe–25%Cr andFe–25%Cr–5%Al prior to oxidation. There were major differencesbetween the (Fe–25%Cr)–(Cr2O3–Y2O3) and(Fe–25%Cr–5%Al)–(Al2O3–Y2O3) systems. A film ofCr2O3 on Fe–25%Cr reduced the oxidation rate and Cr2O3–Y2O3films reduced it still further. A film of Al2O3 onFe–25%Cr–5%Al reduced the rate considerably, butAl2O3–Y2O3 films exhibited rates that were greater than those forAl2O3 alone. A film, which consisted entirely of Y2O3, greatly decreasedthe oxidation rate of Fe–25%Cr, but increased that ofFe–25%Cr–5%Al. The changes in oxidation rate produced byY2O3 in the (Fe–25%Cr)–(Cr2O3–Y2O3) system weremuch greater than those produced in the(Fe–25%Cr–5%Al)–(Al2O3–Y2O3) system. As far asoxidation rate is concerned, the optimum amount of Y2O3 in the(Fe–25%Cr)–(Cr2O3–Y2O3) system was found to begreater than or equal to 40% and less than 100%; in theFe–25%Cr–5%Al)–(Al2O3–Y2O3) systemit was approximately 10%. In thermal-cycling tests, the resultsfor the (Fe–25%Cr)–(Cr2O3–Y2O3) system followedthe same pattern as that for the isothermal tests; a film of Y2O3reduced the oxidation rate and a film of Cr2O3–33%Y2O3reduced it still further.
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  • 44
    ISSN: 1573-4889
    Keywords: Fe–Cr–Al alloy ; oxidation ; molybdenum ; breakaway oxidation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thin foils of Fe–20Cr–5Al alloys are susceptible to breakawayoxidation once the aluminum content of the substrate has fallen below somecritical value. The combined addition of 0.1 wt.% lanthanum and 0, 1, or 2wt% molybdenum has a beneficial effect on the high-temperature oxidation ofsuch foils. Lanthanum has the well-known reactive-element effect on adhesionof the protective alumina scale, thereby increasing the time to onset ofbreakaway oxidation, while, for alloys containing molybdenum, breakawayoxide spreads relatively slowly over the specimen in comparison to alloysthat contain no molybdenum. In particular, molybdenum-containing alloys areable to develop a protective Cr2O3 layer at the breakawayoxide–substrate interface. Conversely, molybdenum-free alloys form aninternal-oxide zone in the substrate adjacent to this interface, rather thana Cr2O3 layer, so breakaway oxide spreads rapidly. A martensitic phase isobserved in the substrate adjacent to the breakaway oxide formed on Fe–20Cr–5Al–La specimens, which means that theα-phase has transferred to the γ -phase at the temperature ofthe oxidation test (1150°C). Conversely, α-phase is retained inthe molybdenum-containing alloy, even after breakaway takes place, sincemolybdenum, which is a strong ferrite former, is enriched in the alloyadjacent to areas of breakaway oxide. The diffusion rate of chromium isslower in the γ than in the α-phase so a continuouschromium-rich oxide layer, which is effective in inhibiting breakawayoxide from spreading, cannot be established at the breakawayoxide–substrate interface for the molybdenum-free alloys.
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    Oxidation of metals 54 (2000), S. 63-71 
    ISSN: 1573-4889
    Keywords: microstructure ; Inconel 625 ; oxidation ; deformation substructure ; deformation twins ; energy-dispersive spectroscopy (EDS) ; internal oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The high-temperature, isothermal-oxidation behavior of a superalloy was studied in the as-rolled and deformed conditions. The microstructural changes occurring during the oxidation of samples were examined using optical, scanning electron microscopy (SEM), fine-probe EDS microanalysis, and X-ray diffraction techniques. The topography of the oxide layers formed in the as-rolled and cold-deformed specimens exposed at various temperatures and time intervals is also examined. The kinetics and microstructural results are presented for the comparative study of the structural changes occurring during high-temperature oxidation. It was found that a Cr2O3 external layer was adherent and uniform on the rolled specimens in comparison to the scattered and preferential oxide developed on the deformed specimens. The latter can be attributed to the concurrent dynamic changes occurring in the deformed substructure that subsequently lead to breaking and spallation of the oxide.
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  • 46
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    Oxidation of metals 54 (2000), S. 121-138 
    ISSN: 1573-4889
    Keywords: titanium aluminides ; oxidation ; oxygen-affected zone ; alpha case ; TEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The isothermal oxidation behavior of binary Ti–25 at.% Al was studiedat 1073, 1173, and 1273 K in air and oxygen with emphasis on themicrostructure of the subsurface zone underneath the external oxidescale. Thermogravimetric analysis, acoustic-emission (AE) analysis, lightmicroscopy, scanning electron microscopy (SEM), atomic force microscopy(AFM), and cross-sectional transmission electron microscopy (TEM) werecarried out. Three layers could be identified in the subsurface regionconsisting of an internal oxidation zone of α-Al2O3,and α-Ti, a ternary phase with the empirical formulaTi–21Al–15O (at.%), and an oxygen penetration zone consisting ofα2-Ti3Al(O).
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  • 47
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    Oxidation of metals 54 (2000), S. 445-456 
    ISSN: 1573-4889
    Keywords: quasicrystals ; aluminides ; oxidation ; nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of a quasicrystal with the nominal compositionAl63Cu25Fe12 was studied around 800°Cin environmental and synthetic air by means of thermogravimetric analysis,electron microscopy, and analytical electron spectroscopy. In an earlyoxidation stage, γ-Al2O3 formed with an orientational relationship tothe quasicrystal. At the oxide–metal interface, γ-Al2O3transformed into large hexagonal shaped α-Al2O3grains. The change in surface morphology indicated that at theoxide–gas interface γ-Al2O3 continued togrow as Θ-Al2O3. Locally the metastable aluminalayer was transformed thoroughly into α-Al2O3,which then continued to grow with a nodular morphology. On top of the oxidenodules, several at.% of Cu2+ were detected.
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  • 48
    ISSN: 1573-4889
    Keywords: oxidation ; marginal chromia formers ; water vapor effect ; chromia evaporation ; breakaway corrosion ; flow-rate dependence ; 304L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of roman PH 2 O and flow rate on the oxidation of 304Lat 873 K in oxygen is reported. High concentrations of water vapor and highflow rates result in breakaway corrosion. The mass gain after 168 hrincreased by four to five times, compared to oxidation in dry O2. Inthe presence of H2O, the corrosion products consisted of arelatively thin (Cr,Fe)2O3 oxide plus large oxide islandsconsisting mainly of Fe2O3. A mechanism explaining theeffect of water vapor on marginal chromia formers is proposed.
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  • 49
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    Oxidation of metals 54 (2000), S. 47-62 
    ISSN: 1573-4889
    Keywords: oxygen sensor ; oxygen pump ; solid-state electrolyte ; ZrO2 ; oxygen partial pressure ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An ultralow oxygen partial pressure-controlling system, based on solid-stateelectrochemical principles, has been developed. This system consists of anoxygen sensor and an oxygen pump and is controlled by a PC computer. Theoxygen sensor is used to measure the oxygen partial pressure in an enclosedsystem, while the oxygen pump is used to transport oxygen from the ambientair into the enclosed system or from the enclosed system to the ambientair. The operating conditions of this system have been studied. The resultsshowed that it can be used to establish a stable oxygen partial pressure inthe range of 10−18∼5×105 Pa (1×10−23∼5 atm)in the enclosed system. This system has been used to investigate theselective oxidation of the Cr and the oxide formation on the surface of aNi–Cr alloy under three different low oxygen partial pressures. Theoxide morphology was studied using atomic force microscopy (AFM). The resultsagreed well with those in the literature and also confirm the reliability of this system.
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  • 50
    ISSN: 1573-4889
    Keywords: TiAl ; oxidation ; phosphorus ; microdiffraction ; doping ; rutile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recently it has been found that very small amounts (a few 100 ppm) of Padded to γ -titanium aluminide can significantly alter the oxidationbehavior between 973 and 1273 K. The mechanism responsible for this changeis, however, still not clear. In the present study, phosphorus wasincorporated into the surface of TiAl (containing 50 at.% Al) by ionimplantation and oxidation tests were carried out at 1173 K inair. Improvement of oxidation resistance is only temporary up to 100 hr forphosphorus-implanted TiAl. After 100 hr, the oxidation rate increases andbreakaway oxidation follows. XRD and EPMA showed that the breakawayoxidation is connected with massive nitride formation. Two different modelsare proposed which can explain the effect of phosphorus additions on theoxidation kinetics of TiAl during the protective stage within the first100 hr. The breakaway effect can be explained by penetration of air to themetal–oxide interface zone because of microcrack formation in theoxide scale, which was experimentally proved by acoustic-emission analysis.
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  • 51
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    Oxidation of metals 54 (2000), S. 339-371 
    ISSN: 1573-4889
    Keywords: Fe–Al alloys ; oxidation ; sulfidation ; nodular growth ; corrosion mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The mechanisms for nodular corrosion-product development were investigatedin various high-temperature gaseous environments. Fe–Al alloys, with5–20 wt.% Al, were exposed in both oxidizing and sulfidizing[p(S2)=10−4 atm, p(O2)=10−25 atm] atmospheres at 700°Cfor times up to 100 hr. The corrosion kinetics were monitored by theuse of a thermogravimetric balance and the morphological developmentthrough light-optical and scanning-electron microscopies,energy-dispersive spectroscopy, electron-probe microanalysis,and quantitative-image analysis. Under both conditions, theelimination of nodule formation was observed by increasing thealuminum content of the alloy, above 5 and 7.5 wt.% Al for oxidizingand sulfidizing environments, respectively, which promoted the growthand maintenance of a continuous surface scale of alumina. For thosealloys that were observed to develop nodular corrosion products, theirmorphological appearance was similar in nature regardless of thecorroding species. The nodules typically consisted of an outeriron-rich product, either sulfide or oxide, that was randomly dispersedacross an alumina scale. Samples from the oxidizing atmosphere displayeda single growth-rate time constant from the kinetics data, suggesting thatthe nodule growth mechanism was by the simultaneous or codevelopment oftwo different (Fe and Al) oxides from the onset of exposure. Measurementof nodule planar diameter and depth of penetration into the alloyindicated that growth occurred through diffusional processes. Kineticsdata from the development of sulfide nodules in the reducingenvironment revealed a different type of mechanism. Multiplegrowth-rate time constants were found due to the localized mechanicalfailure of an initially formed surface scale. At early times in thesulfidizing atmosphere, a low corrosion rate was recorded as acontinuous-alumina scale afforded protection from excessive productdevelopment. However, with the mechanical failure of the scale, sulfurwas able to attack the underlying substrate through a short-circuitdiffusion mechanism that resulted in rapid weight gains from nonprotective,iron sulfide growth. The sulfide morphologies observed were very complex ascontinued growth of the nodule did not solely depend upon the diffusingspecies through the previously formed corrosion products, but also,continued mechanical failure of the oxide scale. It is suggested that thedifference in development mechanisms between the two environments may liein the relative growth rates of the nonprotective, Fe-base corrosionproducts formed.
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    Oxidation of metals 54 (2000), S. 559-574 
    ISSN: 1573-4889
    Keywords: silver–nickel ; mechanical alloying ; oxidation ; two-phase alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Two nanophase Ni-base alloys containing 50 and 25 at.% Ag prepared by mechanical alloying, denoted Ni–50Ag and Ni–25Ag were oxidized in air at 600 and 700°C for 24 hr. Ni–50Ag underwent internal oxidation of nickel, associated with the formation of a continuous outermost layer of silver metal with scaling rates larger than those for pure nickel. On the contrary, Ni–25Ag formed a continuous NiO layer surmounted by a discontinuous silver layer and internal oxidation was suppressed. The oxidation rate of Ni–25Ag decreased with time much more rapidly than predicted by the parabolic rate law during the initial stage and eventually became parabolic, with rate constants much lower than those for the oxidation of pure nickel. These results are attributed to the two-phase nature and, particularly, to the very small grain size of the two alloys.
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  • 53
    ISSN: 1573-1561
    Keywords: 2(5H)-Furanone ; butenolide ; lactone ; butyrolactone ; antibiotic ; biological control ; Pseudomonas chlororaphis ; Pythium ultimum ; Rhizoctonia solani ; Fusarium solani ; Fusarium oxysporum ; Thielaviopsis basicola
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Pseudomonas aureofaciens (= P. chlororaphis) strain 63-28 is a biocontrol agent active against many soil-borne fungal plant pathogens and shows antifungal activity in culture assays. 3-(1-Hexenyl)-5-methyl-2-(5H)furanone was isolated from culture filtrates of this bacterium. The purified furanone showed antifungal activity against Pythium ultimum, Fusarium solani, Fusarium oxysporum, and Thielaviopsis basicola. The ED50S for spore germination of these fungi were 45, 54, 56, and 25 μg/ml, respectively. The compound also inhibited the germ tube growth of Rhizoctonia solani growing from microsclerotia, with an ED50 of 61 μg/ml. The compound is the reduced form of furanones previously described from this bacterium: 3-(1-hexenyl)-5-hydroxy-5-methyl-2-(5H)-furanone and 3-(1-hexenyl)-5-hydroxymethyl-2-(5H)-furanone. This volatile antifungal furanone has structural similarity to other antifungal furanones produced by actinomycetes (Streptomyces spp.), fungi (Trichoderma harzianum), and higher plants (Pulsatilla and Ranuculus spp.). This is the first report of 3-(1-hexenyl)-5-methyl-2-(5H)-furanone produced by a bacterium.
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  • 54
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    Oxidation of metals 53 (2000), S. 1-23 
    ISSN: 1573-4889
    Keywords: Aluminum ; SEM ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fine powders of aluminum were produced in a pilot-plant, inert-gas atomizerwith a “confined-design” nozzle, which operated vertically upward. Argonand helium at 1.85 MPa and nitrogen at 1.56 MPa were used as the atomizingagent. The morphology of the powder particles was examined by SEM. Powderswere sieved dry and wet. The Sauter mean diameter of the powders varied from20.70 to 10.25 μm depending on the atomizing gas. The distribution ofsizes was bimodal. The mean thickness of oxide on the surface of the powderwas calculated from the total oxygen contents of powder samples (determinedby a Leco analyzer). In addition, ESCA measurements and BET tests werecarried out for surface-oxide thickness and area measurements,respectively. The finest powder produced under helium incorporated thinnersurface-oxide layers than the coarser ones produced under argon andnitrogen. This was due to differences in physical properties (such asdensity, thermal conductivity) and flow properties (such as gasvelocity and relative velocity) of the atomizing gases used, i.e., helium,argon, and nitrogen. The oxide was very irregular in thickness in thecoarse-size range of the Al powders produced under argon and nitrogen. Thiswas presumably because of the high- and low-temperature oxidation ofaluminum droplets during the atomization and subsequent solidification andcooling periods leading to the rough surfaces observed with SEMinvestigation in the present work.
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  • 55
    ISSN: 1573-4889
    Keywords: γ-TiAl-based intermetallic alloy ; oxidation ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of microstructure of the two-phase alloyTi–46Al–1Cr–0.2Si on the oxidation behavior in air between600 and 900°C was studied. The oxidation rate, type of scale, and scalespallation resistance were strongly affected by the type of microstructure,i.e., lamellar in as-cast material and duplex after extrusion at1300°C. The oxidation rate was affected by the size and distribution ofthe α2-Ti3Al phase, being faster for the extrudedmaterial with coarse α2-Ti3Al. The type of oxide scaledetermines the spalling resistance. Cast material developed a uniform scalethat spalled off after short exposure times at 800 and 900°C when a criticalthickness was reached. The extruded material presented a heterogeneous scalewith predominant thick regions formed on γ-TiAl-α2-Ti3Algrains and thin scale regions formed on γ-TiAl grains. Thistype of scale could permit an easier relaxation in the matrix of stressesgenerated by both thermal-expansion mismatch between scale and alloy andoxide growth, resulting in a higher spallation resistance.
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    Oxidation of metals 54 (2000), S. 575-589 
    ISSN: 1573-4889
    Keywords: TiAl ; oxidation ; Si3N4 ; dispersed particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation kinetics of TiAl alloys with and without 3 and 5 wt.%additions of Si3N4 particles were studied at 1173 and1273 K in 1 atm of air. The Si3N4 dispersions wereunstable in the matrix phase, so that some of them reacted with titaniumduring sintering to form Ti5Si3 and dissolvednitrogen. The oxide scale formed on TiAl–Si3N4alloys consisted of an outer TiO2, an intermediate(Al2O3+TiO2), and an inner(TiO2+Al2O3) mixed layers. The enhancedalumina-forming tendency, the presence of discrete SiO2 particlesbelow the outer TiO2 layer, and the improved scale adhesion bySi3N4 dispersions were attributable mainly to theincreased oxidation resistance compared to the Si3N4-freeTiAl alloys. Marker experiments showed that, for TiAl–Si3N4 alloys, the primary mode of scale growth was the outward diffusion oftitanium ions for the outer scale and the inward transport of oxygen ionsfor the inner scale.
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  • 57
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    Journal of sol gel science and technology 19 (2000), S. 17-22 
    ISSN: 1573-4846
    Keywords: Reactive materials ; heterogenized reagents ; oxidation ; dehydration ; esterification ; doped sol-gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We advance the use of reactive doped sol-gel materials as heterogeneous reagents for organic-chemistry synthesis. Three approaches were demonstrated with SiO2-based materials: Direct physical entrapment of the organic reagent; in-situ generation of an inorganic reagent within the matrix; and covalent attachment of the reagent to the matrix. With the first, entrapped p-toluenesulfonic acid facilitated the 100% yield esterification of benzoic acid with 1-pentanol, and the 100% dehydration of 1-tetralol to 1,2-dihydronaphthalene; with the second approach, a sol-gel oxidant, SiO2/MnO2 was used to convert benzyl alcohol to benzaldehyde and 1-tetralol to 1-tetralone; and with the third, anchored propylamine facilitated dehydrobromination reactions resulting in double-bond formation. Several other reactions with these reagents are described, and their reactivities analyzed.
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  • 58
    ISSN: 1618-2545
    Keywords: antagonism ; biological control ; Burkholderia sp. ; seed treatment ; soil treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheBurkholderia sp. isolate 87-11 obtained from basidiospores ofLentinus lepideus was antagonistic against severalPythium andRhizoctonia isolates. The bacterium was tested against soilborne diseases of five plants caused byP. aphanidermatum andR. solani by soil and seed application, and its potential as a biocontrol agent is discussed.
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  • 59
    ISSN: 1618-2545
    Keywords: biological control ; citrus greening disease ; Diaphorina citri ; Hirsutella citriformis ; Paecilomyces fumosoroseus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an attempt to suppress the propagation of citrus greening disease in Indonesia, we explored pathogens ofDiaphorina citri which vectors the disease. At two orange orchards, manyD. citri adults were found to be dead and covered with fungal mycelia. Two fungi,Paecilomyces fumosoroseus andHirsutella citriformis, were consistently isolated from the infected insects. Molecular phylogeny of their 18S rDNA sequences showed that they belong to the ascomycetous clade of the Clavicipitales/Hypocreales, which embraces many entomopathogenic fungi. When healthy adults ofD. citri were inoculated with conidia of theP. fumosoroseus, the insects died within 6 d.
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  • 60
    ISSN: 1608-3237
    Keywords: nursery soils ; virgin soil ; phytopathogens ; micromycetes ; conifer seedlings ; microbial antagonism ; Trichoderma ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Soils in the tree nurseries studied were characterized by a lower species diversity of fungi than adjacent virgin soils. In particular, the relative abundances of representatives of the genera Mucor, Chaetomium, and Trichoderma in the nursery soil were two times lower than in adjacent virgin soils. On the other hand, the nursery soil exhibited greater abundances of fungi of the genus Fusarium, which are causative agents of many diseases of conifer seedlings. To appreciate the efficiency of biocontrol of the infectious diseases of conifer seedlings, we introduced several indigenous Trichoderma strains into the nursery soil and found that this affected the species composition of soil microflora considerably. Changes in the species composition of mycobiota beneficially influenced the phytosanitary state of soils and reduced the infectious lodging of conifer seedlings.
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  • 61
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    Journal of porous materials 7 (2000), S. 373-376 
    ISSN: 1573-4854
    Keywords: porous silicon ; superlattices ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Initial stage of porous silicon (PS) formation has been studied in an original way. Multilayer structures constituting of very thin layers of low porosity and thick layers of high porosity have been fabricated and characterised by optical tools and electron microscopy. The non linear behaviour resulting in a change in the dissolution velocity has been quantified by using a stack layer structure. Finally using thermal oxidation it has been shown that, due to the selective oxidation as a function of the porosity, porous silicon can be used to produce a Si/SiO2 like structure.
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    Journal of porous materials 7 (2000), S. 335-338 
    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; calorimeter ; desorption ; activation energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of porous silicon has been studied using differential scanning calorimeter. The oxidation was found to consist of two parts with different activation energies. This indicates the existence of two different reaction mechanism. The results from the hydrogen desorption measurements have been used to study the different oxidation behaviour of the n- and p+-type porous silicon. The results show that the dihydride structure dominates on the surface of the n-type porous silicon, contrary to p+-type porous silicon, where the monohydride is the major structure. Explanations of these features are discussed. Using the activation energy, the surface termination effects are investigated. The best improvement in the activation energy was observed in the sample, whose surface was partially stabilized by ammonium groups.
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    Journal of porous materials 7 (2000), S. 339-343 
    ISSN: 1573-4854
    Keywords: porous silicon ; infrared spectroscopy ; oxidation
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The Si–Si vibrational states near the surface region of porous silicon has been characterized using Fourier Transform Infrared Spectroscopy (FTIR) due to its enlarged surface area. By means of anodic etch and oxidization experiments, two Si–Si vibration modes of porous silicon have been identified as near the surface regions and in the bulk, respectively. The intensity of absorption peak at 620 cm−1, which originates from the Si–Si bonds vibrations on the surface and near surface regions of porous silicon, is found to vary depending on the length of etch and degree of oxidation of porous silicon, which exists before etching and is recovered again after fully oxidation. The peak of 610 cm−1 doesn't change throughout the oxidation experiment, and to be assigned for Si–Si bond vibrations in the bulk. With an extra irradiation of Nd:Yag laser on the PS sample the Raman and FTIR spectra reveal a red shift. These results can give an interpretation to explain the different phenomenon of Si–Si vibrations of Raman and FTIR spectroscopy.
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  • 64
    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; liquid crystal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper we demonstrate the filling of porous silicon (PS) layers with liquid crystals (LC's) in order to control the reflectance electrically. The preparation of PS and the choice of the right group of LC's will be presented. Especially an oxidation of PS is necessary so that the methods and parameters of oxidation will also be discussed. As a first result the increasing and decreasing of the thickness oscillations in the reflectance as a function of the applied voltage can be observed.
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    Journal of porous materials 7 (2000), S. 243-246 
    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; refractive index ; optical waveguide ; optical losses
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Further results on the optical properties of oxidised porous silicon as a function of porosity and oxidation conditions are presented in this paper. The refractive index varies logarithmically with the oxidation time irrespective of the porosity of the sample and the oxidation temperature. Burried waveguides have been realised from as-prepared and oxidised porous silicon. Optical losses of 18 dB cm−1 at λ = 1.3 μm have been obtained after oxidation at 800°C for 35 min.
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  • 66
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    Journal of porous materials 7 (2000), S. 139-142 
    ISSN: 1573-4854
    Keywords: porous silicon carbide ; oxidation ; effective medium theory ; infrared reflectance (or IR) ; reststrahlen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present a study of the infrared reflectance of porous silicon carbide (PSC) formed by the electrochemical dissolution of silicon carbide substrates of both 6H and 4H polytypes. The reflectance from n-PSC, both as-anodized and passivated, is reported for the first time. The passivation of PSC has been accomplished using a short thermal oxidation. Fourier transform infrared (FTIR) reflectance spectroscopy is employed ex situ after different stages of the thermal oxidation process. The characteristics of the reststrahlen band normally observed in bulk SiC are altered by anodization; further changes in the reflectance spectra occur following oxidation for different periods of time. An effective medium theory model that includes air, SiC and SiO2 as component materials is shown to characterize the observed changes in the reflectance spectra after different stages of PSC oxidation.
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  • 67
    ISSN: 1573-5176
    Keywords: active oxygen ; blue-green alga ; cyanobacteria ; liposome ; oxidation ; phycobilin ; phycobiliprotein ; phycocyanin ; radical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The antioxidative activity of phycocyanobilin fromSpirulina platensis was evaluated againstoxidation of methyl linoleate in a hydrophobic systemor with phosphatidylcholine liposomes. Phycocyanobilin as well as phytochemicals includingα-tocopherol, caffeic acid and zeaxanthin,effectively inhibited the peroxidation of methyllinoleate and produced a prolonged induction period.Oxidation of phosphatidylcholine liposomes was alsocontrolled markedly by adding phycocyanobilin orα-tocopherol. Phycocyanobilin was distributedoutside in the liposomes to scavenge radicals fromAAPH and to prevent initiation of radical chainreactions. When the concentrations of phycocyanin andphycocyanobilin in the reaction mixture were adjustedequally on a phycocyanobilin basis, the activity ofphycocyanobilin was almost the same as that ofphycocyanin in the AAPH-containing reaction mixture.The antioxidizing action of phycocyanin prepared fromspray-dried Spirulina almost agreed with thatfrom fresh Spirulina in the AAPH-containingreaction mixture. These results suggest thatphycocyanobilin is responsible for the majority of theantioxidative activity of phycocyanin and may act asan effective antioxidant in a living human body.
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    Chemistry of natural compounds 36 (2000), S. 416-417 
    ISSN: 1573-8388
    Keywords: cotton lignin ; oxidation ; redox catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effects of anthraquinone and demethylated lignin on the oxidation of cotton lignin are compared. Results of the estrogen activity of certain aromatic acids are presented.
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    Chemistry of heterocyclic compounds 36 (2000), S. 1359-1360 
    ISSN: 1573-8353
    Keywords: 1,2,5-thiadiazoles ; 1,2,5-selenadiazoles ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    Chemistry of heterocyclic compounds 36 (2000), S. 870-871 
    ISSN: 1573-8353
    Keywords: sesquiterpene lactones ; britanin ; bigelovin ; oxidation
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    Topics: Chemistry and Pharmacology
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    European journal of plant pathology 106 (2000), S. 203-207 
    ISSN: 1573-8469
    Keywords: biological control ; Mycosphaerella graminicola ; Phaeosphaeria nodorum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study is described which explored the possibility of controlling Stagonospora nodorum and Septoria tritici on wheat using a barley pathogen, Drechslera teres. Pre-treatment of wheat cv. Hussar flag leaves with D. teres resulted in a significant reduction in disease caused by S. nodorum and S. tritici, resulting in a significant increase in grain yield. When cv. Brigadier leaves were treated with D. teres prior to inoculation with S. nodorum there was an initial increase in disease expression whilst D. teres had no effect on symptoms produced by S. tritici on cv. Brigadier. There was significantly less disease on leaves of cvs. Hussar and Brigadier pre-treated with D. teres prior to inoculation with an equal mixture of S. nodorum and S. tritici compared to plants pre-treated with water. It is concluded that D. teres and other non-host pathogens show potential as biological control agents for S. nodorum and S. tritici.
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  • 72
    ISSN: 1573-4935
    Keywords: erythrocyte ; macrophage ; oxidation ; mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Membrane protein modification can change cell surface properties which canbe correlated with altered macrophage-erythrocyte interactions. Mouseerythrocytes were incubated in phosphate buffer for different times toinduce protein modification. Mouse erythrocyte membrane changes wereanalyzed by infrared analyses and gel electrophoresis. Proteolyticdigestion of membrane proteins was observed. After 22 hours preliminaryincubation, the number of erythrocytes adhering to a monolayer ofmacrophages reached a maximum, the majority of which had not beenphagocytosed. Most of the erythrocytes incubated for 40 hours underwentphagocytosis after adhesion to the macrophages.
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  • 73
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    European journal of plant pathology 106 (2000), S. 439-448 
    ISSN: 1573-8469
    Keywords: biological control ; Botrytis cinerea ; Clonostachys rosea ; Gliocladium roseum ; rose ; host development ; wounds ; host residues ; microflora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Development of Clonostachys rosea in rose leaves and petals and control of Botrytis cinerea by the agent were investigated. C. rosea germinated, established endophytic growth, and sporulated abundantly whether the tissues were mature, senescent or dead when inoculated. Germination incidence was moderate on mature and senescent leaves (47% and 35%) and petals (31% and 43%), and high (〉98%) on dead tissues. Sporulation of C. rosea in tissues inoculated when mature, senescent or dead averaged 41%, 61%, and 75% in leaves, and 48%, 87% and 53% in petals. When leaves were wounded with needles before inoculation, germination of C. rosea increased from 45–56% to 90–92%, but sporulation became high (〉 75%) regardless of wounds. When leaves were inoculated with C. rosea at 0–24 h after wounding and subsequently with B. cinerea, germination of the pathogen was reduced by 25–41% and sporulation by ≥ 99%. A humid period prior to inoculation of senescent or dead leaves promoted communities of indigenous fungi, reduced sporulation of C. rosea and B. cinerea, and, in dead leaves, increased control of the pathogen associated with C. rosea. Applied at high density, isolates of indigenous Penicillium sp. and Alternaria alternata from rose interacted with C. rosea and reduced control of the pathogen by 16% and 21%, respectively. In conclusion, C. rosea markedly suppressed sporulation of B. cinerea in rose leaves and petals regardless of developmental stage, minor wounds, and natural densities of microflora. This versatility should allow C. rosea to effectively control inoculum production of B. cinerea in rose production systems.
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  • 74
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    European journal of plant pathology 106 (2000), S. 415-421 
    ISSN: 1573-8469
    Keywords: recirculating solution ; rhizobacteria ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dispersal of root pathogens is a major concern in closed hydroponic cultures. To limit dispersal, ultraviolet (UV) disinfection technology has been used to remove pathogens but its effect on non-target bacterial populations is largely unknown. In this study, the circulating solution was disinfected with various UV doses (i.e., 19, 38, 59, 88 mJ cm−2) before recirculation. At the beginning of the experiment, the hydroponic solution was inoculated with Pythium aphanidermatum at 6.7±1.5 CFU mL−1. Four months later the population density of P. aphanidermatum reached 1030 CFU mL−1 in the control and 1028, 970, 610, and 521 CFU mL−1 in the solutions treated by the above UV doses. In all UV-treated solutions, significant (P〈0.05) reduction of both Pythium and bacterial populations was noted. For the former, its reduction did not result in decrease of Pythium root rot nor increase of tomato fruit yield. For the latter, its reduction showed a concomitant decrease of the populations in the rhizosphere. The bacterial populations in the rhizosphere were 6.77×109 CFU mg−1 fresh roots at the beginning of the experiment and were 7.89×108, 9.93×107, 7.33×107, and 3.51×107 CFU mg−1 fresh roots at the end of the experiment in the control, UV38, UV59, and UV88 treatments, respectively. The bacterial density also decreased with time in the control (UV0) although at a low rate. The results suggest that the attempt to control Pythium root rot by UV irradiation of recirculating solutions to remove P. aphanidermatum also affects the non-target bacterial populations in the rhizosphere. The interaction between the target pathogen and non-target bacterial flora in UV-treated hydroponics needs further investigation.
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  • 75
    ISSN: 1573-8477
    Keywords: biological control ; caterpillar ; coevolution ; geographic mosaic theory ; nucleopolyhedrovirus ; resistance ; Trichoplusia ni ; virulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two laboratory experiments were conducted to examine the possible coevolution of cabbage loopers (Trichoplusia ni) and their S nucleopolyhedrovirus (TnSNPV). At the conclusion of Experiments 1 and 2, T. ni had respectively evolved 4.4 × and 22 × resistance to TnSNPV. The higher level of resistance achieved in Experiment 2 could be due to marginally stronger selection, possibly greater genetic variability in larval resistance to TnSNPV, or both. However, the evolution of resistance was not accompanied by an increased virulence of TnSNPV or a change in the restriction profile of the viral DNA when digested with BamHI, EcoRI, HindIII, PstI, SalI, SstI or XhoI. Little genetic variability for virulence in the initial TnSNPV stocks, low mutation rates and possibly weak selection on the virus are some factors that may have constrained the evolution of TnSNPV. We discuss our results in light of the geographic mosaic theory of coevolution and their implications for the use of TnSNPV as a biological control agent against T. ni.
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  • 76
    ISSN: 1573-904X
    Keywords: methionine-enkephalin ; oxidation ; solid state ; secondary ion mass spectrometry ; peptide stability ; methionine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. A surface sensitive mass spectrometric technique: Time ofFlight Secondary Ion Mass Spectrometry (ToF-SIMS) was introducedto study the solid state instability of a methionine containing peptidecaused by the oxidation of the methionine residue. Methods. The oxidation of a neuropeptide Methinonine-Enkephalin(ME) in air and under UV acceleration was studied by ToF-SIMS. Results. The apparent oxidation rate is defined by the peak ratio ofoxidized molecular ion over unoxidized molecular ion. ME is oxidizedat a faster rate to its sulfoxide derivative in the UV accelerated oxidationenvironment than in lab air. The calibration curve for evaluating theionization probability ratio of the oxidized deprotonated molecular iondivided by the unoxidized deprotonated molecular ion was obtained.This could be used to extract the real oxidation rate of ME in thesolid state. Conclusions. The preliminary results showed that ToF-SIMS with simplesample handling, fast data acquisition, together with excellentsurface sensitivity and detection limit could be an applicable and convenienttool to study peptide reactions in the solid state such as oxidationand deamidation process.
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  • 77
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    Powder metallurgy and metal ceramics 39 (2000), S. 560-562 
    ISSN: 1573-9066
    Keywords: niobium ; coating ; silicon ; corrosion ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Coatings based on TiSi2 have been used to protect niobium alloys from corrosion at temperatures up to 1300°C. Kinetic oxidation curves are given for these coatings on niobium. The phase compositions of the coatings have been determined and also of the layers formed during oxidation. EPMA has been applied to the element distributions in the coating, from which it is concluded that the silicon is mobile. The high resistance to oxygen of coatings based on TiSi2 is due to the formation of films of TiO2 and SiO2 on them.
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  • 78
    ISSN: 1573-5036
    Keywords: biological control ; Paecilomyces lilacinus ; Pseudomonas aeruginosa ; root-knot nematode ; root-infecting fungi ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Efficacy of Pseudomonas aeruginosa alone or in combination with Paecilomyces lilacinus was evaluated in the control of root-knot nematode and root-infecting fungi under laboratory and field conditions. Ethyl acetate extract (1 mg/ml) of P. lilacinus and P. aeruginosa,respectively, caused 100 and 64% mortality of Meloidogyne javanica larvae after 24 h. Ethyl acetate fractions of biocontrol agents were more effective than hexane extracts in the suppression of M. javanica larvae, indicating that active nematicidal compounds are intermediary in polarity. In field experiments, biocontrol fungus and bacterium significantly suppressed soilborne root-infecting fungi including Macrophomina phaseolina, Fusarium oxysporum, Fusarium solani, Rhizoctonia solani and Meloidogyne javanica, the root-knot nematode. P. lilacinus parasitized eggs and female of M. javanica and this parasitism was not significantly influenced in the presence of P. aeruginosa. P. aeruginosa was reisolated from the inner root tissues of tomato, whereas P. lilacinusdid not colonize tomato roots.
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  • 79
    ISSN: 1573-0972
    Keywords: Bacillus megaterium ; B. pumilus ; biological control ; pellet formulation ; Rhizoctonia solani ; storage ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Bacterial formulations, produced using both Bacillus megaterium and B. pumilus individually with pharmaceutical technology, were formulated using a wet granular method. Viability testing in the laboratory revealed that bacterial populations rapidly declined during storage at room temperature (26–30 °C) for 6 months. The scanning electron microscope (SEM) was used to observe bacterial formulations. Both endospores and vegetative cells of B. megaterium and B. pumilus were detected on the formulation surfaces.
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  • 80
    ISSN: 1572-9702
    Keywords: Amblyseius fallacis ; release ; host-plant ; establishment ; biological control ; Panonychus ulmi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amblyseius fallacis Garman has been selected for pyrethroid resistance and mass reared for experimental release as a biological control agent for tetranychid mites on a number of crops in Canada. Several releases of this predator onto apple and peach trees have failed to result in the establishment of A. fallacis, or in the biological control of Panonychus ulmi Koch. Here, we test the hypothesis that the change of host-plant at the time of release is a critical factor in the establishment of A. fallacis for biological control of P. ulmi. Functional and numerical response studies were undertaken on two populations of A. fallacis: a wild strain collected from the canopy foliage of an apple orchard near Vineland, Ontario; and a second strain reared on bean plants in a commercial insectary with Tetranychus urticae as prey. Each population consumed significantly more P. ulmi and produced significantly more eggs when on leaf disks from the plant species they were reared on, than on leaf disks from the novel host plant. A further experiment was conducted to determine if establishment and biological control of mass-reared A. fallacis could be affected by rearing a population for a short term on apple leaves prior to release on apple trees. Three release treatments were made into potted apple trees in a glasshouse, using predators commercially mass-reared on bean and T. urticae: A. fallacis released directly; A. fallacis reared in the laboratory for four weeks on bean and T. urticae; A. fallacis reared on apple leaves and T. urticae for four weeks. They were compared with a control treatment lacking predator release. Contrary to results of the functional and numerical response studies, no difference was observed between release treatments. All release treatments adding A. fallacis resulted in a similar, if limited, degree of biological control of P. ulmi. These results indicated that there may be short-term effects of host plant on the establishment of A. fallacis and biological control of P. ulmi, which in our study were observed as an initial reduction of the predatory response. However, in a test, the predators appeared to overcome these short-term effects and successfully established on the new host-plant to control P. ulmi.
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  • 81
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    Experimental and applied acarology 24 (2000), S. 913-926 
    ISSN: 1572-9702
    Keywords: Rhipicephalus appendiculatus ; Amblyomma variegatum ; Boophilus deceloratus ; Beauveria bassiana ; Metarhizium anisopliae ; entomopathogen ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When ticks were sealed in nylon tetrapacks and infected with the entomogenous fungi, Beauveria bassiana and Metarizium anisopliae and maintained in potted grass in the field, the fungal oil formulations (109 conidia per ml) induced 100% mortality in larvae of Rhipicephalus appendiculatus and Amblyomma variegatum, whereas mortalities in nymphs varied between 80–100% and in adults 80–90%. The aqueous formulations (109 conidia per ml) induced mortalities of 40–50% and reductions in egg hatchability of 68% (B. bassiana) and 48% (M. anisopliae) when sprayed on Boophilus decoloratus engorging on cattle. The strains of B. bassiana and M. anisopliae isolated from naturally infected ticks were also found to induce high mortalities in both R. appendiculatus and A.variegatum in tetrapacks placed in potted grass. Both aqueous and oil-based formulations were found to be effective, although the latter induced higher mortalities. These fungal strains in aqueous formulation (108 conidia per ml) suppressed on-host populations of adult R. appendiculatus by 80% (B. bassiana) and 92% (M. anisopliae) when sprayed on tick-infested grass once per month for a period of 6 months. The feasibility of using entomogenous fungi for tick control in the field is discussed.
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  • 82
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    Topics in catalysis 11-12 (2000), S. 195-204 
    ISSN: 1572-9028
    Keywords: 3-fluorotoluene ; 3-fluorobenzaldehyde ; iron molybdate ; Fe–Mo/boralite ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The gas-phase selective synthesis of 3-fluorobenzaldehyde from 3-fluorotoluene over bulk iron molybdate and Fe–Mo oxide in a host boralite sample is described. The latter samples, prepared by adding Fe and Mo by chemical vapor deposition to the boralite, show high selectivity in oxidation, making yields of 3-fluorobenzaldehyde of over 40% possible. The pretreatment of the zeolite to eliminate extra-framework boron improves behavior, and secondary post-addition of molybdenum by CVD to increase the Mo/Fe ratio in the catalyst has a similar enhancing effect. The behavior of Fe–Mo/boralite samples proves significantly better, in terms of both specific activity (per mass of active phase) and selectivity, than bulk Fe2(MoO4)3, but at high conversion lower selectivities are found probably due to the presence of limitations in the backdiffusion of 3-fluorobenzaldehyde.
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  • 83
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    Topics in catalysis 11-12 (2000), S. 213-222 
    ISSN: 1572-9028
    Keywords: CaO ; MgO ; carbon monoxide complexes ; oxidation ; adsorption calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The heat evolved during the adsorption and oligomerization of CO on outgassed CaO and MgO has been determined with a heat-flow calorimeter. The chemisorbed complexes formed include highly-conjugated (CO) n 2 anions which impart colour to the oxides. The reaction of these complexes with oxygen has been quantified calorimetrically and correlated with changes observed spectroscopically.
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  • 84
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    International journal of infrared and millimeter waves 21 (2000), S. 31-37 
    ISSN: 1572-9559
    Keywords: HgCdTe ; oxidation ; surface treatment ; passivation ; XPS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This report presents a surface pre-treatment method of LPE HgCdTe epilayer to reduce and remove the oxides and contaminants. The surface oxidative characterization of LPE HgCdTe epilayer has been studied by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). HgCdTe surface exposed by various processing steps has been measured and analyzed, the results show the native oxide film can be removed by the solution of lactic acid in ethylene glycol after etching by bromine in absolute ethyl alcohol. It indicates that the mainly optical and electrical parameters of LPE HgCdTe epilayer have not been changed. It is evident that the pre-treatment before HgCdTe surface passivation affects the passivant/HgCdTe interface properties.
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  • 85
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    Experimental and applied acarology 24 (2000), S. 453-462 
    ISSN: 1572-9702
    Keywords: biological control ; natural control ; acaricide ; Tetranychus kanzawai ; population increase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Problems with spider mites first appeared in Taiwan in 1958, eight years after the importation of synthetic pesticides, and the mites evolved into major pests on many crops during the 1980s. Of the 74 spider mite species recorded from Taiwan 10 are major pests, with Tetranychus kanzawai most important, followed by T. urticae, Panonychus citri, T. cinnabarinus, T. truncatus and Oligonychus litchii. Most crops suffer from more than one species. Spider mites reproduce year-round in Taiwan. Diapause occurs only in high-elevation areas. Precipitation is the most important abiotic factor restricting spider-mite populations. Control is usually accomplished by applying chemicals. Fifty acaricides are currently registered for the control of spider mites. Acaricide resistance is a serious problem, with regional variation in resistance levels. Several phytoseiid mites and a chrysopid predator have been studied for control of spider mites with good effect. Efforts to market these predators should be intensified so that biological control can be a real choice for farmers.
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  • 86
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    Experimental and applied acarology 24 (2000), S. 463-495 
    ISSN: 1572-9702
    Keywords: risk analysis ; transgenic arthropods ; pest management programs ; biological control ; genetic improvement ; genetic control ; horizontal gene transfer ; pesticide resistance ; containment facilities and procedures ; Wolbachia ; predatory mites ; Metaseiulus occidentalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ability to genetically engineer arthropods using recombinant DNA meopens new opportunities for improving pest management programs but also creates new responsibilities, including evaluation of the potential risks of releasing transgenic arthropods into the environment. It is now becoming easier to transform diverse species of arthropods by a variety of recombinant DNA methods. Useful genes and genetic regulatory elements are being identified for pest arthropods, but less effort is being expended to identify genes that could improve the efficacy of beneficial arthropods. A transgenic strain of the natural enemy Metaseiulus (= Typhlodromus or Galendromus) occidentalis (Acari: Phytoseiidae) was developed using a method termed maternal microinjection. This transgenic strain was released into an experimental site on the campus of the University of Florida in 1996 after extensive reviews by the University of Florida Biosafety Committee, Florida Department of Agriculture and Consumer Services, United States Department of Agriculture Animal and Plant Health Inspection Service, and the United States Fish and Wildlife Service. The short term releases established a precedent for releasing a transgenic arthropod but, at present, no guidelines are available that would allow transgenic arthropods to be released permanently into the environment. Several scientific, environmental, and policy issues must be resolved before transgenic pests or beneficial arthropods can be deployed in practical pest management programs.
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  • 87
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    Experimental and applied acarology 24 (2000), S. 319-335 
    ISSN: 1572-9702
    Keywords: spider mites ; genetic marker ; acaricide ; pest management ; biological control ; diapause ; Tetranychus kanzawai ; Tetranychus urticae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spider mite biology and control in Japan were reviewed. Seventy-eight spider mite species of 16 genera (Family Tetranychidae) have been recorded in Japan. Several of the species recently described were separated from a species complex comprising strains with different ecological performance such as host range. These separations were first supported by crossing experiments and then confirmed by molecular genetic studies. Spider mite control in Japan is still dependent on heavy acaricide spraying in order to attain products of extremely high quality. The commercial use of natural enemies in spider mite management has just started.
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  • 88
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    Experimental and applied acarology 24 (2000), S. 579-596 
    ISSN: 1572-9702
    Keywords: Tetranychus urticae ; ambulatory dispersal ; temperature ; humidity ; mortality ; emigration ; immigration ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a greenhouse and in an open field, aspects of aerial and ambulatory dispersal of the phytoseiid mite, Neoseiulus fallacis (Garman) were studied with a focus on events that would occur after aerially dispersing mites had landed on soil or associated substrates. We measured recovery of predators on lima bean plants (Phaseolus lunatus L.) that were infested with the two-spotted spider mite, Tetranychus urticae Koch. Factors thought to affect movement and colonization were distance to a receiver unit from a release (landing) point, intervening soil surfaces such as clods, gravel, fine soil and grass, and management of soil surfaces such as mulching, watering or both. In the field, the effect of distance (0.11–1.76 m) from a landing point to a receiver unit was significant, with a negative log-linear relationship. Soil surfaces such as clods and management actions such as watering with mulching allowed for more capture of predators on bean plants with prey than did other treatments. Environmental conditions greatly affected survival of N. fallacis.Predators in the field that were present on bare soil suffered high mortality (ca. 90%) at fluctuating daytime conditions of 26.4 ± 4.8°C and 56 ± 13.4% RH. Predators only suffered 10% mortality in the greenhouse under the same setting, but under more controlled and favorable environmental conditions. Effects of environmental conditions, mode of dispersal and implications to biological control are discussed.
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  • 89
    ISSN: 1573-3017
    Keywords: parasitoid ; Trichogramma ; biological control ; chloronicotinyl ; thiacloprid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Thiacloprid, a new chloronicotinyl insecticide, is targeted chiefly to control aphid pest species in orchards and vegetables. In a standard IOBC glass plate assay, residues of thiacloprid (SC 480) severely affected adult stages of the cereal aphid parasitoid Aphidius rhopalosiphi whereas pre-imaginal stages (which develop within the host) remained unaffected. As for A. rhopalosiphi, the pre-imaginal stages of the crop-relevant egg parasitoid T. cacoeciae were not adversely affected by a spray treatment with thiacloprid (SC 480). However, when treated host eggs were stored under greenhouse conditions, the emergence success of ecdysed parasitoids was significantly reduced. This is assumed to be caused by thiacloprid residues that had been deposited on the host egg cuticle during spray treatment and which were ingested by the parasitoids during emergence, when they were biting its way through the host egg cuticle. In contrast, if treated host eggs were subjected to field exposure conditions before emergence of the parasitoids, no statistically significant reduction in emergence success was recorded. Moreover, the fitness of parasitoids emerging from treated host eggs was not reduced compared to untreated parasitoids. Since pre-imaginal stages comprise a major part of a parasitoid population and were not affected in a lethal or sublethal way by thiacloprid (SC 480), we conclude that a spray treatment with thiacloprid (SC 480) in the field will not significantly interfere with the pest control function of a parasitoid fauna in the target crops.
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    Water, air & soil pollution 118 (2000), S. 13-26 
    ISSN: 1573-2932
    Keywords: aeration ; decomposition ; nitrite ; nitrogen oxides ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Studies on the decomposition/oxidation of nitrite at differentpH values and aeration flow rates were investigated using abench-scale batch reactor. The conditions were pH 2.85, 3.50,5.80, 7.0, and 11.6, and with or without aeration at airflowrates of 1.50, 2.25, and 3.25 L min-1.Decomposition/oxidation of nitrite may be described by apseudo-first order expression, and the rate constants fornitrite decomposition/oxidation ranged from 1.2 ×10-6 s-1 to 1.12 × 10-4 s-1 depending on the experimental conditions. The rate ofdecomposition/oxidation of nitrite was found to increase for lowpH conditions and for high airflow rates. The experimentalresults showed that the dominant reaction in thedecomposition/oxidation of nitrite in low pH solutions and inthe presence of some aeration was most probably thedecomposition of nitrous acid to NO and NO2. Oxidation ofnitrite to nitrate appeared to proceed in a smaller proportionin comparison to the breakdown of nitrous acid to nitrogen oxidecompounds. Results from this study showed that emissions ofnitrogen oxides from nitrite-containing solutions are possible ifthe solutions were agitated and the pHs of the solutions wereless than 6.
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  • 91
    ISSN: 1573-4854
    Keywords: oxidized porous silicon ; anodization ; oxidation ; dielectric isolation ; optical waveguide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A brief review of 20-years research of formation, processing and utilizing of oxidized porous silicon (OPS) is presented. Electrolytes to form porous silicon (PS) layers, special features of PS chemical cleaning and thermal oxidation are discussed. OPS application for dielectric isolation of components of bipolar ICs and for the formation of silicon-on-insulator structures has been demonstrated. Although these OPS-based techniques have found limited current commercial use, experience gained is applicable to the fabrication of optoelectronic devices. Specifically, integrated optical waveguides based on OPS have been developed.
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    Journal of porous materials 7 (2000), S. 63-66 
    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; IR spectroscopy ; vibrational analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation behavior of porous silicon under various environments of dry and wet air, and solution with and without appropriate oxidant at mild temperatures has been investigated. The progress of oxidation was followed by infrared spectroscopy. The presence of water vapor greatly accelerates the oxidation rate in comparison with the rate in dry air. The oxidized states are clarified with the help of oxidation experiments of partially hydrogen-desorbed porous silicon, which does not contain SiH2 and SiH3 as the hydride species. An oxidation mechanism is proposed to explain that oxidation is accelerated in the presence of water vapor and at the partially hydrogen-desorbed porous silicon. Further, oxidation behavior of porous silicon in solution containing appropriate oxidant is also investigated. The rate is very rapid and the oxidation does not produce the back-bond oxidized state of OySiHx in contrast to the oxidation in air.
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  • 93
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    Reaction kinetics and catalysis letters 69 (2000), S. 31-38 
    ISSN: 1588-2837
    Keywords: MMH ; oxidation ; gas-phase ; oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The objective of this study is to characterize the lifetime of monomethylhydrazine mixed with O2, both in the gas phase, at 298 K. A detailed kinetic model has been built to allow a numerical study of the homogeneous MMH/O2 reactivity.
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    Reaction kinetics and catalysis letters 71 (2000), S. 115-120 
    ISSN: 1588-2837
    Keywords: Mechanism ; oxidation ; alkylperoxo complexes ; vanadium ; NMR spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Using 51V, 17O, 13C and 1H NMR spectroscopy, vanadium(V) alkylperoxo complexes VO(OOtBu)k(OnBu)3-k, where k = 1, 2 and 3, were characterized in the reaction of VO(OnBu)3 with tBuOOH in CH2Cl2.
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  • 95
    ISSN: 1588-2837
    Keywords: Hydrogen sulfide ; oxidation ; iron compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The correlation of the state of iron in supported Fe/Al2O3 catalysts with catalytic properties in H2S oxidation, studied by Mössbauer spectroscopy, indicates that the Fe oxide particles promote the formation of sulfur, whereas FeS2 catalyzes the H2S oxidation to SO2.
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  • 96
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    Reaction kinetics and catalysis letters 71 (2000), S. 319-323 
    ISSN: 1588-2837
    Keywords: Benzene ; oxidation ; aqueous phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Aqueous phase heterogeneous catalytic oxidation of benzene by dissolved oxygen is reported. Using a bimetallic platinum-ruthenium catalyst supported on a high surface area activated carbon, good conversions were obtained at temperatures above 100°C and space-times greater than 40 seconds. Complete conversion of benzene to carbon dioxide and water was achieved at 100°C with a reactor space-time of 300 s.
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  • 97
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    Reaction kinetics and catalysis letters 69 (2000), S. 247-252 
    ISSN: 1588-2837
    Keywords: Phosphorous acid ; oxidation ; kinetics ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation of lower phosphorus oxyacids by benzyltrimethylammonium chlorobromate (BTMACB) proceeds by a mechanism involving a hydride-ion transfer from oxyacids to the oxidant in the rate-determining step.
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  • 98
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    Reaction kinetics and catalysis letters 69 (2000), S. 369-374 
    ISSN: 1588-2837
    Keywords: Thioacids ; oxidation ; mechanism ; hexamethylenetetramine-bromine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Oxidation of thioacids by hexamethylenetetramine-bromine proceeds through an intermediate complex in the pre-equilibrium and its subsequent decomposition in the slow step.
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  • 99
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    World journal of microbiology and biotechnology 16 (2000), S. 115-134 
    ISSN: 1573-0972
    Keywords: Bacteria ; biocontrol ; biological control ; compost ; disease ; fungi ; microbiology ; pathogen ; suppression ; turf ; turfgrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The relationships among the chemical, physical and biological aspects of compost and their role in suppression of turfgrass pathogens are reviewed. The composting process, mediated by microbial activity, is affected by physical and chemical characteristics which include temperature, aeration, moisture content, C:N ratio and pH. In the absence of parameter restrictions, the microbial community follows a predictable successional pattern resulting in the re-colonization of compost with metabolically active mesophilic populations that can be suppressive towards plant pathogens. Although mechanisms of suppression are not fully understood, those postulated include physiochemical and biological characteristics. The physiochemical characteristics of composts can alter suppressive properties through direct effects on pathogens and antagonistic microorganisms, or indirect effects on host systems through the supply of nutrients, improvement of soil structure, porosity and water retention capabilities, along with other factors. Biological characteristics centre on microbial community involvement in suppressive mechanisms, which can include one or a combination of competition for nutrients, antibiosis, lytic and other extracellular enzyme production, parasitism, predation and host-mediated induction of resistance. As a result of the potential benefits of compost, there is considerable interest in determining the capacity for composts to suppress turfgrass pathogens. Although the exact mechanisms of suppression are largely unknown, there appear to be several factors that play an integrated role. The use of composts that successfully suppress turfgrass diseases will permit a reduction in the use of chemical controls, and slow the development of fungicide resistance.
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  • 100
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    International journal of peptide research and therapeutics 7 (2000), S. 347-351 
    ISSN: 1573-3904
    Keywords: chromogenic substrates ; oxidation ; Oxone® ; para-nitroanilides ; solid-phase synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new strategy has been developed for the rapid synthesis ofpeptide para-nitroanilides (pNA). The method involves derivatization of commercially available tritylchloride resin(TCP-resin) with 1,4-phenylenediamine, subsequent coupling withdesired amino acids by the standard Fmoc protocol, and oxidationof the intermediate para-aminoanilides (pAA) with Oxone®. This procedure allows easy assembly of the desired para-aminoanilides (pAA) on standard resin and efficient oxidation and purification of the corresponding para-nitroanilides (pNA). The method allows easy access to any desired peptide para-nitroanilides, which are useful substrates for the characterization and study of proteolytic enzymes.
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