Codeposition of SiC powders with nickel in a Watts bath

The effect of the silica layer of SiC powder on ionic adsorption was studied in a Watts nickel plating bath. PZC (point of zero charge) measurement suggested that SiC powder has a tendency to release H⁺ at pH > PZC ( 2.2), and the amount of Ni²⁺ adsorbed on the surface of the SiC increased with increased pH of the Watts bath. Experimental results showed that SiC powders not only catalyzed the adsorption of hydrogen atoms but also had a significant effect on hydrogen evolution during electrodeposition if the solution pH was less than or equal to 2.0 (PZC. Furthermore, SiC powders have a shielding effect which prevents OH^– from being released into the solution under an applied potential, which results in more Ni(OH)₂ in the deposited layer. SiC powders also promote further adsorption of intermediates of nickel on the electrode surface, as shown by impedance studies.     

Effect of juvenile hormone analog,fenoxycarb, on pheromone production byIps paraconfusus (Coleoptera: Scolytidae)

Topical application of the juvenile hormone analog, fenoxycarb, in acetone induced newly emerged male California five-spined ips,Ips paraconfusus Lanier, to become attractive to females, as measured by positive responses to male abdominal extracts in a laboratory bioassay. Two pheromones, ipsdienol and ipsenol, were detected by gas chromatography in the abdominal extracts of fenoxycarb-treated males. Pheromone production was minimal at a dose of 0.1 g/insect of fenoxycarb, maximal at 10 g, and was reduced to unmeasurable amounts at a dose of 100 g. In comparison, peak production of pheromones was induced at a dose of 0.1 g/insect of natural juvenile hormone (JH III). Treatment with 10 g of fenoxycarb resulted in the occurrence of pheromones 12 hr after exposure, maximal pheromone content between 16 and 20 hr, and undetectable amounts after 36 hr. The demonstration that fenoxycarb is an active juvenile hormone analog for a bark beetle suggests that it may have practical utility in managing these insects.     

Preparation of Bi1−xSbx films by electrodeposition

A method has been developed to produce composition modulated Bi_1–x Sb _x alloys by electrodeposition. The electrolyte which consists of NaCl 4 M and HCl 1 M (pH 0) in aqueous medium, allows codeposition of bismuth and antimony to be accomplished at room temperature on glassy carbon. The composition of the films, their crystal structure, morphology and resistivity were studied as a function of electrochemical parameters and bath composition. It is shown that the electrodeposits are monophasic and exhibit a polycrystalline state. The obtained alloys represent a continuous series of solid solution. The film composition is dependent on the applied current density. The electrical resistivity is of the order of 3–7 m.     

Mechanism and Mechanoactivation Effects in Solids Subjected to Jet Grinding

Mechanical activation of disperse particles is considered a route to self-excited activity of a solid subjected to strain under strongly nonequilibrium conditions. According to the self-oscillatory prefailure theory, self-excitation of the material at the self-resonance stage of disintegration is central to the generation of finely disperse (finer than 100 m) activated particles.     

Electrodeposition of lead dioxide on carbon substrates from a high internal phase emulsion (HIPE)

PbO₂ coatings on carbon electrode substrates were produced by anodic electrodeposition from a stationary high internal phase emulsion (HIPE) with the bath components added in the water phase. The deposits have a distinct structure consisting of 10–50 m high pyramidal aggregates, pitted with smaller pores. This is attributed to the growth of the deposits through the aqueous network of the HIPE emulsion that is, through the tortuous paths formed by its interconnected water cavities. The coatings thus produced are characterised by enhanced electrochemical activity towards the PbO₂/PbSO₄ transformation.     

An electron microscope investigation of electrolytic copper powders

The size and nature of copper powders deposited in conditions close to those found in production units are investigated with a scanning electron microscope. It is shown that an increase in the current density or the concentration of sulphuric acid decreases the size of the particles and makes their dendritic structure more pronounced. In contrast, an increase of copper ion concentration or agitation increases the size of the particles and obscures their dendritic character. It is shown that the changes in the particle size and type are primarily dependent on cathode potential. A change from –100mV to —900mV versus SCE causes a decrease in the powder size from 80–100m to 5–10m and a successive appearance of the following types of particles: (a) round particles or dendrites with round tips, due to electrocrystallization in one plane (a compact deposition); (b) a transient structure, apparently a change to polycrystal growth on the pyramidal tips; (c) particles with pyramidal tips and (d) dimeric and trimeric dendrites.     

Contact sex pheromone in the tsetse flyGlossina pallidipes (Austen) Identification and Synthesis

Adult maleG. pallidipes attempted to copulate with decoys treated with a branched paraffin obtained from laboratory-reared female flies. The compound causing maximal response was isolated and identified as 13,23-dimethylpentatriacontane. The synthesized compound elicited increasing responses with increasing doses. This sex- and species-specific compound was always present in physiological amounts in females, as it increased from 2 g at emergence to 10 g per female at 14 days. It was present in wild-caught females from a wide geographical range.     

Coating and Characterization of Titania Membrane on Porous Ceramic Supports

In this article, we reported experimental results on the development of microstructure of the membrane layer deposited on a porous support. The changes in porosity and mean pore diameter were followed as a function of layer thickness. It was found that in addition to particle packing and sintering within the membrane layer, the porous structure of support surface also exhibited certain effects on membrane microstructure until a critical thickness was reached. After that, the porous characteristics of a membrane would be totally determined by the packing and sintering characteristics of particles. It was also shown that the surface roughness could be reduced from about 1.5 m of the support, to 0.8 m after coating with 0.5 m titania particle and further reduced to about 0.55 m after another coating with 30 nm titania colloids. With proper dispersing and coating procedures, we could reduce the mean pore diameter from about 1.5 m of the support to 0.12 m, while the gas permeability was only changed from 500 × 10–7 to 250 × 10–7 mol/m2 s Pa.     

The effects of different manufacturing techniques on the availability of sulfate to pasture from mixtures of elemental sulfur with either triple superphosphate or partially acidulated reactive phosphate rock

Six different preparations of elemental sulfur incorporated into triple superphosphate and a single mixture of elemental sulfur with partially acidulated reactive phosphate rock were evaluated for the rate of release of sulfatesulfur to pasture at two sites.The method of preparing the mixtures affected the size of sulfur particles released on dispersion of fertilizer granules. The rates of release of sulfate from oxidation of the elemental sulfur was controlled by the fineness of the particles of elemental sulfur. For rapid release of sulfate by oxidation a mixture prepared by sintering elemental sulfur with mature triple superphosphate was the most effective. It contained sulfur particles of diameter less than 75 m. The mixtures which comprised synthetic blends of elemental sulfur of particle size less than 150 m or 150–250 m, each with mature triple superphosphate, released sulfate at a progressively slower rate than that with particles less than 75 m. However, both proved effective sulfur fertilizers releasing sulfate over a 1–2 year period. In contrast, mixtures prepared by adding molten elemental sulfur during the process of manufacturing triple superphosphate resulted in a coarser distribution of sulfur particles and a slow release of sulfate to plants.The incorporation of sulfur into a mixture with partially acidulated reactive phosphate rock was made via the dispersion of molten sulfur into phosphoric acid which was then used to partially acidulate phosphate rock. The resultant sulfur particles ranged from finely divided (e.g. 38% < 150 m) to moderately fine (81% < 500 m), and the release of sulfate was predictable based on the particle size distribution.Differences between the two experimental sites in uptake of plant sulphate reflected the different pastures grown. At the cool temperate coastal site a ryegrass/clover pasture rapidly took up sulfate as it was released into the topsoil. Inland, in the summer-dry environment, the uptake of released sulfate by the deep-rooted lucerne pasture was delayed for 12–18 months, indicating that the sulfate uptake increased after the nutrient had leached beyond the surface soil layer.     

Responses of male codling moths (Laspeyresia pomonella) to codlemone and other alcohols in a wind tunnel

The primary pheromone (E,E)-8,10-dodecadien-1-ol (I, codle-mone), 11 further alcohols, and binary blends of both were evaluated for attractiveness as defined by the percentage ofL. pomonella males showing oriented upwind flight terminated by landing at the source within 10 min after release. Sources of I were attractive from 10^–5 g to 10¹ g, with approx. 70% males responding at 10^–3–10^–1 g. Most other alcohols also showed attractiveness, but the dose-response curves differed greatly with respect to the range of effective lure doses as well as the maximum response level reached at any dose. (E,E)-7,9-Undecadien-1-ol (III) revealed a dose-response curve similar in shape to I but shifted towards higher concentrations. (E,E)-8,10-Tridecadien-1-ol (II) and (E)-8,10-undecadien-1-ol (IV) exhibited threshold values of 10^–5 g (same as for I) and were effective over, respectively, seven and nine decades of source load, but they did not reach a response level of 40% at any test amount. (E)-9,11-Dodecadien-1-ol (VI) and the monoenes (E)-8-, (E)-10-, and (Z)-10-dodecen-1-ol (VIII-X) showed weak attractivity restricted to one to three test doses. Upwind approaches that broke off a few centimeters from the source were rarely seen in tests with I but frequently occurred with some of the analogs. When combined with 10^–3 g of I, all alcohol analogs showed inhibitory properties, although the amounts required to obtain a significant lowering of response differed by up to 10⁵-fold. This amount was the lowest (10^–4 g) for the positional isomer VI, and the highest (10¹ g) for undecan-1-ol (XI) and dodecan-1-ol (XII). With some mixtures, the presence of the inhibitor appeared to cause an alteration in landing behavior. No synergistic effects were seen in these tests. The results are briefly considered with respect to the sensory perception of the test stimuli and the involvement of minor components in the female pheromone blend.     

Feeding and Growth of Plutella xylostella and Spodoptera eridania on Brassica juncea with Varying Glucosinolate Concentrations and Myrosinase Activities

We measured feeding behavior, feeding damage, and larval growth of the crucifer specialist, Plutella xylostella and the generalist, Spodoptera eridania, on the cotyledons of 14 homozygous lines of Brassica juncea differing in myrosinase activity and glucosinolate profiles. The proportion of time feeding and area damaged by P. xylostella were lower on lines with high myrosinase activities [0.49–0.73 nmol glucose released/mg tissue(fresh weight, FW)/min] than on lines with low myrosinase activities [0.20–0.31 nmol glucose released/mg tissue(FW)/min]. In contrast, the proportion of time feeding and area damaged by S. eridania were not related to myrosinase activity, but were lower on cotyledons of lines with high glucosinolate concentrations [6.8–21.3 g/g(FW)] than on lines with low glucosinolate concentrations [0.09–0.61 g/g(FW)]. Relative growth rates (RGR) of both insect species were lower on lines with high glucosinolate concentrations, but were not related to myrosinase activity in the lines. In toxicity experiments that used artificial diets, allyl isothiocyanate, but not allyl glucosinolate, was lethally toxic to neonate P. xylostella (LC₅₀s of 1.54 mol/g, and 100 mol/g, respectively), whereas isothiocyanate and the glucosinolate were lethally toxic to neonate S. eridania (LC₅₀s of 3.42 and 6.73 mol/g, respectively). We interpret these results to indicate that myrosinase activity might be more important for plant defense against specialist insects that have adaptations to intact glucosinolates, but less important for defense against generalists, which are susceptible to the intact glucosinolates.     

Fate of quinolizidine alkaloids through three trophic levels:Laburnum anagyroides (Leguminosae) and associated organisms

The quinolizidine alkaloids (QA) of golden rain,Laburnum anagyroides, and those of phytophagous insects associated with the plant, as well as of parasitoids of the latter, were analyzed by capillary GLC and GLC-MS. The alkaloid content in samples of vegetative plant parts was high at the beginning of the season, then decreased, while that of reproductive organs was high throughout flowering, pod formation, and maturation. The analyses showed that the QA of the plant passed through two higher trophic levels (herbivorous insects and their parasitoids) and that the alkaloid pattern changed little during the passage. The alkaloids were present in two phytophagous insect species associated with golden rain: the predispersal seed predator,Bruchidius villosus [5–13g/g fresh weight (fw)], andAphis cytisorum (182–1012g/g fw), an aphid that feeds on shoots, leaves, and inflorescences. Braconid and chalcidoid parasitoids emerging from the bruchid host also contained alkaloids (1.3–3g/g fw), as did three foraging ant species,Lasius niger, Formica rufibarbis, andF. cunicularia (45g/g fw), that visited the aphid colonies or honeydew-covered leaves of aphid-infested plants. The hypothesis that developing bruchid larvae and/or the plant manipulate QA supply to infested seeds was not supported, because QA content of leftover endosperm in seeds after bruchid development was similar to that of uninfested seeds. The frass of developing bruchid larvae was rich in QA (31g/ g dry weight). While aphids sequestered, the bruchid larvae took up and eliminated QA with the frass without chemical transformation.     

Effect of Volatile Constituents from <Emphasis Type="Italic">Securidaca</Emphasis><Emphasis Type="Italic">Longepedunculata</Emphasis> on Insect pests Of Stored Grain

Securidaca longepedunculata Fers (Polygalaceae) is commonly used as a traditional medicine in many parts of Africa as well as against a number of invertebrate pests, including insects infesting stored grain. The present study showed that S. longepedunculata root powder, its methanol extract, and the main volatile component, methyl salicylate, exhibit repellent and toxic properties to Sitophilus zeamais adults. Adult S. zeamais that were given a choice between untreated maize and maize treated with root powder, extract, or synthetic methyl salicylate in a four-way choice olfactometer significantly preferred the control maize. Methyl salicylate vapor also had a dose-dependant fumigant effect against S. zeamais, Rhyzopertha dominica, and Prostephanus truncates, with a LD₁₀₀ achieved with a 60 l dose in a 1-l container against all three insect species after 24 hr of exposure. Probit analyses estimated LD₅₀ values between 34 and 36 l (95% CI) for all insect species. Furthermore, prolonged exposure for 6 days showed that lower amounts (30 l) of methyl salicylate vapor were able to induce 100% adult mortality of the three insect species. The implications are discussed in the context of improving stored product pest control by small-scale subsistence farmers in Africa.     

Effects of three phenolic compounds onLemna gibba G3

Lemna gibba L. G3, (duckweed) was used as a bioassay organism to test the allelochemical effects of salicylic acid (SA), ferulic acid (FA), and umbelliferone (UM). Growth rate (K), dry weight (DW) and total chlorophyll (CHL) production were measured after seven days of growth. The bioassay procedure used 50 ml of E medium with and without sucrose in 125-ml Erlenmeyer flasks plus the selected concentration of allelochemical. At concentrations of 50 M and greater, SA caused inhibition of K and DW production inL. gibba G3, while the threshold for CHL reduction was 20 M. FA inhibited the DW and CHL production at 100 M when the compound was auto-claved in E medium containing sucrose. Treatments of UM were least toxic with an inhibition threshold of 500 M for K and DW production in medium without sucrose. UM did not reduce CHL production until 750 M. In some cases, different thresholds of inhibition were observed depending on the presence or absence of sucrose and tartaric acid in the medium, and whether or not the chemicals were autoclaved with the medium.This research was presented by the senior author as partial fulfillment for the Master of Arts degree, Biology Department, Hood College, Frederick, Maryland. Mention of a trade name or proprietary product does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion of other products that may be suitable.     

Novel Antifeedant and Insecticidal Compounds from Avocado Idioblast Cell Oil

Several insecticidal compounds have been identified by bioassaydriven fractionation of avocado, Persea americana Mill, idioblast cell oil. A flash chromatography fraction of the oil showed substantial toxicity to early instars of the generalist insect herbivore, Spodoptera exigua (Hübner) (100% mortality after seven days). Following further fractionation, five biologically active compounds, 2-(pentadecyl)furan, 2-(heptadecyl)furan, 2-(1E-pentadecenyl)furan, 2-(8Z,11Z-heptadecadienyl)furan, and the triglyceride triolein, were identified. Several minor components were also tentatively identified, including 2-(1Z-pentadecenyl)furan, 2-(1E-heptadecenyl)furan, and 2-(1E,8Z,11Z-heptadecatrienyl)furan. Several 2-alkylfurans of this type have been reported previously from avocado (Persea spp.) and have received the common name of avocadofurans. The major compounds were tested individually for toxic and growth inhibitory effects. Individually, the compounds had low to moderate toxicity. Of these, 2-(pentadecyl)furan had the greatest effects, with an LC₅₀ value of 1031 g/g. At concentrations of 600 g/g or higher in diets, larval growth was inhibited by >70% compared to controls. The analogous 2-(heptadecyl)furan had an LC₅₀ value of 1206 g/g, and also significantly reduced larval growth (>75% versus controls) at concentrations of >600 g/g. The unsaturated analogs 2-(1E-pentadecenyl)furan and 2-(8Z, 11Z-heptadecadienyl)furan were less toxic. Triolein was only weakly toxic, with an LC₅₀ value of 10,364 g/g diet. Larval growth was inhibited only at concentrations of 7000 g/g or higher. The potential of avocadofurans in insect control is discussed.     

Interactions between pheromone traps with different strength lures for the pine beauty moth,Panolis flammea (Lepidoptera: Noctuidae)

Catches of malePanolis flammea in traps baited with lures containing 25 g of sex attractant are enhanced when in the proximity of traps baited with 125-g lures. The degree of enhancement is increased as the intertrap distance is decreased, and when the low-dose trap is upwind of the high-dose one. The patterns of alteration in trap catch suggest that moths initially attracted by one lure may divert into other traps, which may be either upwind of the original trap (overshooting), or downwind (undershooting). Overshooting can result in up to fivefold increases in catch and may provide a useful method for estimating the attractant zone of particular lure/trap combinations.     

Dihydromatricariate-based triglycerides,glyceride ethers,and waxes in the australian soldier beetle,Chauliognathus lugubris (Coleoptera: Cantharidae)

The soldier beetleChauliognathus lugubris is shown to contain triglycerides and glyceride ethers of 8-dihydromatricaria acid, and waxes of the C₁₂ homolog, of this acid, as well as the previously reported free acid. The triglycerides contain one, two, or three dihydromatricariate moieties, with any remaining positions esterified with normal fatty acids. The glyceride ethers were monostearyl ethers of glycerol esterified with dihydromatricaria acid and oleic or linoleic acid. The waxes, which also include a dihydromatricaria chromophore in the alcohol moiety, occur only in the females and are present in paired accessory glands in the abdomen. The ethers are restricted to females and appear to be associated with developing eggs. The triglycerides are much more abundant in females than males. Triglycerides, glyceride ethers, and waxes represent about 95% of the dihydromatricariate moiety (average, ca. 590 g) in females with free acid the remainder; in males free acid is present to over 50% (ca. 22 g) and the remainder is triglyceride (ca. 15 g). Larvae contain mainly tridihydromatricariate-substituted triglyceride and a smaller quantity of the free acid.     

Crosslinked particles of poly[n-(1-phenylethyl)acrylamide]: Preparation and application as chromatographic stationary phases

Crosslinked particles of poly [N-(1-phenylethyl)acrylamidel have been successfully prepared by suspension polymerization of N-(1-phenylethyl) acrylamide and ethylene dimethacrylate in water using poly(vinyl alcohol) as dispersant. The particle morphology is investigated by optical microscope and scanning electron microscope (SEM). The pressure resistance of the crosslinked particles, evaluated after packing as stationary phases of high-performance liquid chromatography (HPLC), increases from 7 to 20 kg/cm² as the mole percent of ethylene dimethacrylate increases from 10% to 30%. The particles were sieved into four sieve fractions, i.e. 37–63 m, 63–88 m, 88–105 m, and 105–149 m, and packed into HPLC columns, respectively. The chromatographic performances of these columns have been investigated in HPLC system thoroughly, using benzene as solute and mixtures ofn-hexane and 2-propanol as eluents. The crosslinked particles show potential application as stationary phases for HPLC.     

Effect of the particle size on the activity of MoO x C y catalysts for the isomerization of heptane

Molybdenum trioxide samples having apparent particle sizes (APS) of 5 and 20 .m were partially reduced under flow of a mixture of H₂/n-heptane during 4 h. X-ray diffraction and Raman spectroscopy showed the typical structural transformation of MoO₃ into MoO_xC_y and MoO₂. These structural changes occur preferentially on the {0k0} planes. After the reduction treatment the resulting materials, having surface areas of 23 and 53 m²/g, were evaluated in the isomerization of n-heptane at 643 K and 18.5 bar. The catalyst with an APS of 20 .m showed a maximum conversion around 70%, while for the catalyst with an APS of 5 .m the maximum conversion was 34%. The lower activity of the 5 .m MoO_xC_y catalyst seems to be related to a faster rate of formation of oxygen vacancies and rearrangement of the lattice into a more stable and less active structure in the case of small-size particles, due to a higher concentration of terminal Mo=O bonds along the a- and b-axes, which facilitate the electrophilic attack by hydrogen on the (010) plane.     

Looplure efficacy and electrophysiological responses in three plusiinae species

Source concentration differences of (Z)-7-dodecen-1-ol acetate, or looplure, were evaluated for field trapping efficiency and electrophysiological responses with malePseudoplusia includens (Walker),Trichoplusia ni (Hubner) andRachiplusia ou (Guenné) (Lepidoptera: Noctuidae). Sticky traps baited with 1000 g of the lure captured a significantly greater (P < 0.05) number of maleP. includens andT. ni than any other concentration;R. ou males were caught at a greater rate in traps baited with 100 g of looplure, significantly more (P < 0.05) than with 1000 g. Electroantennogram (EAG) studies demonstrated that antennae of maleP. includens have a lower response threshold to looplure than eitherT. ni orR. ou antennae, the latter demonstrating the highest significant threshold of response. No differences in the stimulus-response functions of the three species were detected.Lepidoptera: Noctuidae.