Electrosynthesis of 4,4′-dinitroazobenzene on PbO2 electrodes

Parameters which affect the electrosynthesis of 4,4-dinitroazobenzene from p-nitroaniline on platinum and PbO₂ electrodes were investigated and optimum conditions were determined. Maximum conversion efficiency for electrosynthesis was 95% with a pure -PbO₂ electrode. It was found that the electrocatalytic activity of a PbO₂ electrode depends upon its / ratio and its degree of crystallinity. The effects of the added base and water on the conversion efficiency were also elucidated.     

Suppression of the α → β-nickel hydroxide transformation in concentrated alkali: Role of dissolved cations

The presence of dissolved cations such as Al and Zn in alkaline electrolyte (6 M KOH) suppresses the -nickel hydroxide transformation. The uptake of Al (10 mol%) and Zn (30 mol%) exhibited by the active material likely stabilizes the -phase. Dissolved Al is deleterious to the performance of the nickel hydroxide electrode, whereas, dissolved Zn enhances the specific discharge capacity of nickel hydroxide by approximately 25% showing that the mode of metal uptake is different in the two cases.     

Isolation and identification of male medfly attractive components inLitchi chinensis stems andFicus spp. stem exudates

Short-range attraction/feeding stimulation of male Mediterranean fruit flies [Ceratitis capitata (Wiedemann), (Diptera: Tephritidae)] to a stem extract of a host plant,Litchi chinensis Sonn. (Sapindaceae), and to milky exudates from stems of nonhost plants,Ficus retusa L. andF. benjamina L. (Moraceae), were attributed to the presence of the sesquiterpene -copaene. The presence of -copaene in the milky exudate from stems ofF. benghalensis L. is also suggested as eliciting similar behavioral responses in male medflies. The presence of minor quantities of -ylangene in the plants and its contributory effects to the behavioral response of male medflies is discussed. Short-range attraction/feeding stimulation of male medflies to equal amounts of -ylangene-free -copaene samples (94.5%+), prepared from -copaene-enriched angelica seed oil and copaiba oil, respectively, showed no difference in intensity of response. -Ylangene elicited a slightly less intense response for male medflies than -copaene.Names of products in this paper are included for the benefit of the reader and do not imply endorsement or preferential treatment by USDA.     

α-Copaene, A Potential Rendezvous Cue for the Mediterranean Fruit Fly, Ceratitis Capitata?

-Copaene, a potent attractant for male Mediterranean fruit flies, Ceratitis capitata, is found as a minor component in the essential oils of various plant species, including its hosts such as orange, guava, and mango. Despite the specific attraction of male flies and the wide distribution of the compound in host plants, the biological significance of -copaene remains unknown. In a laboratory test, leklike behavior of C. capitata was induced artificially by using a plastic leaf model treated with (+)--copaene. It was also found that (+)--copaene affected virgin females, provoking "pseudomale" courtship behavior in the short-range bioassay. Mating occurred exclusively on the artificial leaves treated with -copaene, suggesting the compound potentially serves as a chemical cue to facilitate orientation of flies to the rendezvous site.     

Acetone conversion to isobutene in high selectivity using zeolite β catalyst

The catalytic activity of the proton forms of zeolite and ZSM-5 are compared for the conversion of acetone. Zeolite demonstrates markedly enhanced selectivity to isobutene and selectivities of >80% can be achieved for conversions up to 65%. In contrast high selectivities to isobutene with ZSM-5 can be attained only at very low conversions (5%).     

Response of the Seven-spot Ladybird to an Aphid Alarm Pheromone and an Alarm Pheromone Inhibitor is Mediated by Paired Olfactory Cells

Electrophysiological responses of adult seven-spot ladybirds, Coccinella septempunctata, to (E)--farnesene, an aphid alarm pheromone, and (–)--caryophyllene, a plant-derived alarm pheromone inhibitor, were investigated by recording from single olfactory cells (neurons) on the antenna. Cells having high specificity for each of the two compounds were identified. Furthermore, these two cell types were frequently found in close proximity, with a larger amplitude consistently recorded for the cell responding specifically to (E)--farnesene. Preliminary behavioral studies in a two-way olfactometer showed that walking adults were significantly attracted to (E)--farnesene; this activity was inhibited with increasing proportions of (–)--caryophyllene. The possible ecological significance of colocation or pairing of olfactory cells for semiochemicals with different behavioral roles is discussed.     

Multichemical defense of plant bugHotea gambiae (westwood) (Heteroptera: Scutelleridae)

Chemical defense in larvae of the plant bugHotea gambiae has been investigated. Results of analyses (GC, GC-MS) on the secretions from the three dorsally situated larval abdominal defense (scent) glands are reported. The secretion from the first abdominal gland consists of a mixture of C₁₀ and C₁₅ isoprenoids: (C₁₀) -pinene, -pinene, limonene, -phellandrene; (C₁₅) -caryophyllene, caryophyllene oxide, -humulene, and (the major component) humulene epoxide II. The secretions from the second and third abdominal glands are similar mixtures consisting of (E)-2-decenal, (E)-4-oxohex-2-enal, andn-tridecane together with lesser amounts of (E)-2-hexenal,n-dodecane, and other materials. Isoprenoid defense is now known from four species of plant bugs (Heteroptera) associated with Malvaceae.     

Response of the European elm bark beetle,Scolytus multistriatus (Coleoptera: Scolytidae), to isomers and components of its pheromone

Laboratory bioassays (two methods) and field tests demonstrated synergistic action of the three components [(–)-4-methyl-3-heptanol (I); (–)-2,4-dimethyl-5-ethyl-6,8-dioxabicylo[3.2.1]octane (-multistriatin) (II); and (–)--cubebene (III)] of the pheromone bouquet ofScolytus multistriatus. Individually and in pairs the components were slightly attractive; I+II was clearly the most active doublet. Indirect evidence indicates that only one of the four enantiomers of I is active. Of the , , and isomers of II, only the is active. With the addition of compound I, slightly attractive extract from mated females became nearly as active as extract from virgin females.     

Isolation and identification of cotton synomones mediating searching behavior by parasitoidCampoletis sonorensis

In laboratory bioassays, the parasitoidCampoletis sonorensis was attracted to the following sesquiterpenes isolated from cotton essential oil: -humulene, -bisabolene, -caryophyllene oxide, spathulenol, -bisabolol, and a new, naturally occurring bisabolene-related alcohol, (2-p-tolyl-6-methylhept-5-en-2-ol) which we name gossonorol. This is the first report of spathulenol in cotton. -Caryophyllene, a major component of cotton, was not attractive to the parasitoids. The response of the parasitoids to these compounds and the possibility of augmenting parasitoid activity in the field by manipulating plant secondary metabolites is discussed.Synomone: A chemical produced or acquired by an organism that benefits both the emitting and receiving organisms (Nordlund and Lewis, 1976).     

Lean NOx catalysis over alumina‐supported catalysts

aluminasupported catalysts show promise as lean NO_x catalysts. The role of alumina in influencing the structural and chemical properties of the active phase supported on it is discussed using some effective aluminabased lean NO_x catalysts. These include Ag/Al₂O₃, CoO_x/Al₂O₃ and SnO₂/Al₂O₃. Alumina plays an important role in stabilizing Ag in the oxidic phase and cobalt in the 2+ oxidation state. For SnO₂/Al₂O₃, alumina increases the SnO₂ surface area. On both Ag/Al₂O₃ and SnO₂/Al₂O₃, alumina also participates actively in the NO_x reduction reaction. An active organic intermediate is formed on Ag or Sn oxide which reacts with NO_x subsequently on alumina to form N₂.     

Allelopathic Effects of Volatile Monoterpenoids Produced by <Emphasis Type="Italic">Salvia leucophylla</Emphasis>: Inhibition of Cell Proliferation and DNA Synthesis in the Root Apical Meristem of <Emphasis Type="Italic">Brassica campestris</Emphasis> Seedlings

Salvia leucophylla, a shrub observed in coastal south California, produces several volatile monoterpenoids (camphor, 1,8-cineole, -pinene, -pinene, and camphene) that potentially act as allelochemicals. The effects of these were examined using Brassica campestris as the test plant. Camphor, 1,8-cineole, and -pinene inhibited germination of B. campestris seeds at high concentrations, whereas -pinene and camphene did not. Root growth was inhibited by all five monoterpenoids in a dose-dependent manner, but hypocotyl growth was largely unaffected. The monoterpenoids did not alter the sizes of matured cells in either hypocotyls or roots, indicating that cell expansion is relatively insensitive to these compounds. They did not decrease the mitotic index in the shoot apical region, but specifically lowered mitotic index in the root apical meristem. Moreover, morphological and biochemical analyses on the incorporation of 5-bromo-2-deoxyuridine into DNA demonstrated that the monoterpenoids inhibit both cell-nuclear and organelle DNA synthesis in the root apical meristem. These results suggest that the monoterpenoids produced by S. leucophylla could interfere with the growth of other plants in its vicinity through inhibition of cell proliferation in the root apical meristem.     

Factors governing the electrochemical synthesis of α-nickel (ii) hydroxide

The electrodeposition of -nickel hydroxide is promoted by the simultaneous chemical corrosion of the electrode by an acidic nitrate bath. Chemical corrosion results in the formation of a poorly ordered layered phase which is structurally similar to -nickel hydroxide and provides nucleation sites for the deposition of the latter. Therefore under conditions which enhance corrosion rates such as low current density (<1.3 mA cm–2), high temperature (60 C), high nickel nitrate concentration ( 1M) and the resultant low pH (1.7), -nickel hydroxide electrodeposition is observed, while -nickel hydroxide forms under other conditions. Further, -nickel hydroxide deposition is more facile on an iron electrode compared to nickel or platinum.     

Kinetics and Mechanism of Copolymerization of α-terpineol with Methylmethacrylate in Presence of Azobisisobutyronitrile as an Initiator

The radical copolymerization of -terpineol with methyl-methacrylate in xylene at 80±0.1C for 50 minutes in the presence of azobisisobutyronitrile (AIBN) follows ideal kinetics and results in the formation of a functional and random copolymer. The activation energy is 33 KJ/mole. The IR spectrum and NMR spectra of the copolymer(s) shows the bands at 1750 and 3400 cm^–1 for ester group of methylmethacrylate and alcoholic group of -terpineol and peaks at 3 to 4 for methoxy group and at 6.5 to 7.5 due to alcoholic group of methylmethacrylate and -terpineol repectively. The values of reactivity ratios, calculated by Kelen–Tüdos method, are r ₁ (MMA) = 0.18 and r ₂ (-terpineol) = 0.046. The Alfrey-Price; Q–e parameters for -terpineol has been calculated as 0.149 and 2.486. The mechanism of copolymerization has been elucidated and it is concluded that the double bond present in the monocyclic ring of -terpineol is an active site for copolymerization and the alcoholic group of -terpineol remain to give functional copolymer.     

Cobalt‐catalyzed amination of 1,3‐cyclohexanediol and 2,4‐pentanediol in supercritical ammonia

The onestep procedure of amination of bifunctional secondary alcohols to diamines has been investigated in a continuous fixedbed reactor. Application of supercritical NH₃ as a solvent and reactant suppressed catalyst deactivation and improved selectivities to amino alcohol intermediates, whereas selectivities to diamines remained poor (8–10%). The main reason for the low diamine selectivity of 1,3dihydroxy compounds is water elimination leading to undesired monofunctional products via ,unsaturated alcohol, ketone or amine intermediates. This side reaction does not occur with 1,4dihydroxy compounds which afford high aminol and diamine selectivities under similar conditions. Amination of secondary diols with ammonia was found to be faster, but less selective than that of the corresponding primary 1,3propanediol.     

Asymmetric structure analysis of active surface-sites by in situ polarized total-reflection fluorescence EXAFS

An in situ polarization-dependent total reflection fluorescence yield EXAFS system has been developed to analyze the asymmetric structures of catalytically active metal sites on single crystal surfaces. This technique separately reveals the bonding feature parallel and perpendicular to the support surface. The systems of Cu ion on -quartz(0001), Co oxide on -alumina(0001), and Pt₄ on -alumina(0001) were investigated as model surfaces of supported catalytic systems. The location of Cu sites on -quartz(0001), the epitaxial growth mode of Co₃O₄ on -alumina(0001), and the Pt raft structure with metal-support interaction in Pt₄ / -alumina(0001) were observed.     

Oxidation of α- and β-pinene catalyzed by MnIII (Salen) Cl·H2O

The cationic complex Mn^III (Salen) is a very effective catalyst for the oxidation of both- and-pinene. The higher selectivity towards epoxide formation supports the rebound oxygen mechanism. A turnover of 40 was obtained for both compounds after 16 h of reaction with a molar ratio 10.011 (feedstock: catalyst: iodosobenzene) and conversions between 50 and 60% were observed. A very high selectivity (55%) was determined for epoxide formation from -pinene. The good selectivity observed for myrtanal isomers (6.5 and 23.2%) from-pinene is related to the prior formation of the 1,2-epoxides.     

Polyimides based on “multiring” flexible diamines

The five benzene rings-containing (hereafter for convenience, referred to as five-ringrd) diamines ad-bis[4-(4-aminophenoxy)phenyl]-1,4 (or 1,3)-diisopropylbenzene (p- or m-3) were prepared by a nucleophilic substitution of ,-bis(4-hydroxyphenyl)-1, 4 (or 1,3)-diisopropylbenzene (p- or m-1) with p-chloronitrobenzene in the presence of K₂CO₃ and then hydro-reduced. The polyimides were synthesized from diamine 3 and various aromatic dianhydrides via the two-stage procedure that include ring-opening polyaddition in DMAc to give poly(amic acid)s, followed by thermal conversion to polyimides. The poly(amic acid)s had inherent viscosities of 0.63–1.54 dL/g depending on the dianhydrides used. Almost all the poly(amic acid)s could be solution-cast and thermally converted into transparent, flexible, and tough polyimide films. These polyimides have glass transition temperatures in the range of 186–290°C and almost no weight loss up to 500°C in air or nitrogen atmosphere. The polyimide obtained from pyromellitic dianhydride and diamine m-3 showed two endothermic peaks of 270 and 300°C on the diagram of differential scanning calorimetry (DSC), and the other polyimides showed no endotherms on their DSC traces.     

Surface of a Titanium Target After Interaction with Shaped‐Charge Jet Particles

Coatings containing WC_1-x and W₂C_1-x tungsten carbides were produced on titanium targets by a shapedcharge explosion. The experiment used conical liners with a cone angle of 30° manufactured from a mixture of fine powders of tungsten, graphite, and ammonium nitrate. A comparative quantitative xray analysis of the top and bottom layers of the coating was performed. For the phase WC_1-x in the bottom layer, the value of the cubic unit cell parameter falls outside the range known in the literature. Microhardness in different segments of the target was studied.     

Both Ovarian Fluid and Female Urine Increase Sex Steroid Hormone Levels in Mature Atlantic Salmon (Salmo salar) Male Parr

We compared the ability of urine and ovarian fluid from female Atlantic salmon (Salmo salar) to stimulate increase in plasma concentrations of sex steroid hormones in mature conspecific male parr (priming effect of the stimuli). We also tested the hypothesis that prostaglandin F₂ (PGF₂) may act as a priming pheromone in the tested stimulants. Individual males of salmon parr were exposed to female urine, ovarian fluid, urine–ovarian fluid mix, or PGF₂. Plasma concentrations of the sex steroids of 17,20-dihydroxy-4-pregnen-3-one (17,20-P) were higher in males exposed to urine, ovarian fluids, and PGF₂ compared to control males. PGF₂ and a mixture of urine and ovarian fluid also gave increased concentrations of 11-ketotestosterone (11-KT). Concentrations of PGF₂ were higher in ovarian fluids than in urine. A behavior test with mature male parr in a fluviarium showed neither attraction to nor avoidance of 0.1 nM PGF₂, but plasma levels of 17,20-P were significantly higher in exposed males compared to controls.     

Inhibition of β-Glucosidase and Esterase by Tannins from Betula, Salix, and Pinus Species

The reaction of tannin fractions isolated from the bark of Betula, Salix, and Pinus species with two enzymes, -glucosidase and esterase, was investigated. The influence of precipitation to the hydrolytic capacity of -glucosidase also was studied. All tannins studied precipitated -glucosidase and esterase, and moderate differences in the precipitating capacities of the tannins were observed. Interestingly, complex formation between -glucosidase and tannin did not markedly affect the activity of the enzyme. Therefore, complex formation during the insect/herbivore feeding does not necessarily change the defense activity of phenolic glycosides or decrease activity of digestive enzymes.