High productivity analysis of15N and13C in soil/plant research

On-line sample preparation and analysis enables faster testing of hypotheses in biological research, particularly in field experiments where many samples must be processed to integrate spatial variability. Soil scientists were first to recognise the need for a fast, easy-to-use¹⁵N analyser to replace the isotope ratio mass spectrometer (IRMS) and Kjeldahl-Rittenberg sample preparation. Development has since led to a variety of continuous-flow methods. Today's instruments accept solid, liquid or gaseous samples in their naturally occurring form (leaves, soil, algae, soil gas) and process 100–125 samples per day. Automated sample preparation and analysis takes 3–10 minutes per sample.By 1984, three groups had interfaced an automated nitrogen analyser to an IRMS. Continuous-flow combustion converted N in plant tissue or soil to a pulse of N₂ gas, which was taken to the mass spectrometer by a helium carrier. Throughput increased from 20 to 100 analyses per day and only 5µg N was required compared with 50µg N for Kjeldahl-Rittenberg preparation and IRMS analysis. 1984 was also the year in which a gas chromatograph (GC) was first used on-line with an IRMS for isotopic analysis of individual compounds separated from a mixture (GC-IRMS).In 1987, a software-controlled Automated Nitrogen Carbon Analyser-Mass Spectrometer (ANCA-MS) was developed for solid and liquid samples. Both¹⁵N and¹³C were measured to (SD, n = 5) 0.0002 atom%, enough for tracer studies. Less hardware made it portable, enabling use at remote sites. Software control enabled submicrogram quantities of N to be measured by moving the O₂ pulse, with its N₂ blank, out of phase with the sample. Software also allows an accelerated mode for¹⁵N, doubling throughput for a small loss in precision.Several workers have developed micro-diffusion methods for ANCA-MS determination of NH ₄ ⁺ and NO ₃ ^- in KCl extracts. In 1990, a dual isotope mode was added for sequential analysis of¹³C and¹⁵N from the same sample. In 1992 a new, 120° deflection, mass analyzer was designed to improve accuracy and precision at the high pressures used in CF-IRMS. Its precision of < 0.1¹³C for > 100µg C and < 0.3¹⁵N for > 50µg N extends ANCA-MS to natural abundance applications.Gaseous samples were first analyzed by CF-IRMS by manually injecting into the carrier flow of an ANCA-MS instrument. The initial interest was for¹³C breath tests - radiation-free non-invasive tests of metabolic function. Demand for these led to the development in 1989 of an automated GC-IRMS method to separate and measure¹³C in CO₂ from human breath. The instrument was further developed for isotopes in other gases:¹³CO₂,¹⁵N₂,¹⁵N₂O, and¹³CH₄ above soil;¹⁸O from water equilibrated with CO₂ and¹⁵NO from NO ₃ ^- in KCl plant extracts. The dual isotope mode allows¹⁵N to be measured in both N₂ (mass 28) and N₂O (mass 44) separated from the same sample. Recently GC-IRMS has been used to determine¹⁵N in N₂O produced from NO ₂ ^- or NO ₃ ^- in KCl soil extracts.We predict that these simpler, automated instruments and the growth of analytical services will encourage more widespread use of stable isotope techniques by agricultural researchers.     

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.     

Effects of radial diffusion on the efficiency of porous flow-through electrodes

A model is proposed to evaluate the effect of radial diffusion on the efficiency of porous flow-through electrodes. The model includes the electrode parameters of porosity (), thickness (L) and equivalent pore radius (R), the superficial flow speed of the electrolyte (v) and the molecular diffusivity of the reactant in the electrolyte (D). The effects of these variables are incorporated in a dimensionless group(L) =vR ²/2DL which controls the conversion efficiency of the electrode. Satisfactory agreement was found between the model predictions and the experimental results of several authors on different electrode-electrolyte systems over a wide range of conditions. Implications of this work for design purposes are outlined. The effect of radial diffusion limitations on the voltage efficiency of the electrode is also discussed. It is shown that radial diffusion effects predominate under conditions of large values of pore radius, polarization and exchange current density, and small values of diffusivity.List of symbols b RT/F(V) - c ⁰ Feed reactant concentration, (mol cm^–3) - c _s Reactant concentration at the electrode surface - c(x) Average or mixing-cup concentration of reactant atx - c _m(x) Reactant concentration at the centre of the pore - c _w(x) Reactant concentrations at the wall of the pore - d Equivalent pore diameter (cm), Equation 2 - D Diffusion coefficient of reactant (cm² s^–1) - f Conversion efficiency of the electrode - i _L Maximum obtainable limiting current, (A cm^–2) Equation 1 - i ₀ Exchange current density based on bulk concentration,c ⁰ - i ₀ Normalized exchange current densityi ₀ SL/i_L - L Electrode thickness (cm) - n Number of electrons - q Tortuosity factor - R Equivalent pore radius (cm) - (Re) Reynolds number (Re) =/sv - S Specific surface area of the porous medium (cm^–1) - (Sh) Sherwood numberK _md/Dd - superficial flow speed (cm s^–1) - x Distance, see Fig. 3. - Transfer coefficient - (x) Polarization at distancex - Porosity - (x) Dimensionless group, see Equation 6 - v Kinematic viscosity (cm² s^–1)     

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.     

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.     

Study of the β — α solid-solid transition of isotactic polypropylene by synchrotron radiation

Synopsis The transformation of the -modification into -modification in isotactic polypropylene was investigated by WAXS, DSC and dilatometric methods. The temperature and time dependent WAXS spectra were made by using high-intensity synchrotron radiation. The - transformation was followed by short time exposures. The transformation of the -modification was found to act toward the increase in the total crystallinity.     

Critical solution point and chain dimension of branched-polystyrene solutions

Summary Critical solution point and chain dimension were measured for branched polystyrene(BPS) in solution as a function of molecular weight(M) and compared with those for linear polystyrene(LPS). The critical concentration _c of BPS was quite different from that of LPS at a fixed M, but the same at a fixed overlap-concentration ^*, i.e., plots of _c vs. ^* fall on a single straight line for both BPS and LPS (gf_c ^*). Reduced critical temperature _c defined by gt_c=(–T_c)/ [T_c: critical temperature, : the -temperature] was related to _c as _{c c} ² for BPS, whereas _{c c} for LPS.     

Antifungal polyoxygenated fatty acids fromAeollanthus parvifolius

Two polyoxygenated fatty acids with antifungal activity have been isolated from aerial parts ofAeollanthus parvifolius (Labiatae) using bioassay-guided isolation procedures. Spectroscopic analysis was used to identify the compounds as (Z)-4,9-diacetoxy-6,7-epoxy-5-hydroxy-8-oxododeca-2-enoic acid and (Z)-4,6,7,9-tetraacetoxy-5-hydroxy-8-oxododeca-2-enoic acid. Both of these compounds inhibited spore germination ofCladosporium cucumerinum. Minimum inhibitory doses were 1 µg and 5 µg, respectively, but only the former inhibited germination ofAspergillus niger at a dose of 5 µg. Neither compound exhibited antibacterial activity. (Z)-4,9-Diacetoxy-6,7-epoxy-5-hydroxy-8-oxododeca-2-enoic acid reduced the hyphal growth ofPythium ultimum. The mode of action was not resolved but did not involve either the disruption of the cell wall membrane or the inhibition of extracellular enzymes. Application of (Z)-4,6,7,9-tetraacetoxy-5-hydroxy-8-oxododeca-2-enoic acid to seedling plants did not give any protection against fungal attack, and indeed the compound appeared to be phytotoxic.     

Effect of fungal metabolite peramine and analogs on feeding and development of argentine stem weevil (Listronotus bonariensis)

Peramine, a pyrrolopyrazine alkaloid produced by the fungal endophyte of perennial ryegrassAcremonium lolii, deterred the feeding of both adults and larvae of the graminacious herbivore, the Argentine stem weevil (Listronotus bonariensis), at 0.1 g/g and 10 g/g, respectively. In a no-choice test fewer stem weevil larvae fed and developed on diet containing as little as 2 g/g peramine. The proportion of larvae which did not develop beyond the first instar was higher on diet containing peramine and appeared to be due to a higher proportion of larvae which did not feed. For larvae which fed on the peramine-containing diet, feeding scores and times to pupation were not significantly different from those of controls. A number of simple peramine analogues showed feeding-deterrent activity against adult weevils, indicating the importance of the pyrrolopyrazine ring system of peramine in determining feeding-deterrent activity.     

Sex pheromone of the chokecherry leafroller moth,Sparganothis directana

(E)-9,11-Dodecadienyl acetate and (Z)-9,11-dodecadienyl acetate in conjunction with (E)-11-tetradecenyl acetate and (Z)-11-tetradecenyl acetate were found to comprise the sex pheromone ofSparganothis directana, based on chemical analysis, electroantennogram tests, and field trapping. (E)-9-Dodecenyl acetate and (Z)-9-dodecenyl acetate were also found in gland extracts but did not influence trap catches. The relative amounts of these compounds in the gland were 3521928 106, in the order named. Only (E)-9,1 1-dodecadienyl acetate, (E)-11-tetradecenyl acetate, and (Z)-11-tetradecenyl acetate were required for attraction of males to traps, dispensed in the relative amounts 501238, respectively.Lepidoptera: Tortricidae.Supported by National Science Foundation grant PCM 78-13241.     

Ethyl m-Digallate from Red Maple, Acer rubrum L., as the Major Resistance Factor to Forest Tent Caterpillar, Malacosoma disstria Hbn.

An ethanolic extract of red maple (Acer rubrum L.) leaves (RME) applied to trembling aspen (Populus tremuloides Michx.) leaves reduced feeding in choice test assays with forest tent caterpillar larvae (Malacosoma disstria Hbn.) (FTC), whereas a trembling aspen foliage extract, similarly applied, stimulated feeding. Compounds isolated from the RME were gallic acid, methyl gallate, ethyl gallate, m-digallate, ethyl m-digallate, 1-O-galloyl--D-glucose, 1-O-galloyl--L-rhamnose, kaempferol 3-O--D-glucoside, kaempferol 3-O--D-galactoside, kaempferol 3-O--L-rhamnoside, kaempferol-3-O-rhamnoglucoside, quercetin 3-O--D-glucoside, quercetin 3-O--L-rhamnoside and quercetin 3-O-rhamnoglucoside, (–)-epicatechin, (+)-catechin and ellagic acid. All of the gallates, (–)-epicatechin, and kaempferol 3-O--L-rhamnoside deterred feeding on trembling aspen leaf disks when applied at 0.28 mg/cm². The two digallates deterred feeding by 90% and were the most effective. HPLC analysis indicated that ethyl m-digallate is present in amounts 10–100 × higher in RME (2.5–250 mg/g) than any other compound. Thus, ethyl m-digallate appears to be the major compound protecting red maple from feeding by FTC, with a minor contribution from other gallates.     

Interactions of alkaloids with galeal chemosensory cells of colorado potato beetle

The galeal chemosensory system of the adult Colorado potato beetle was used as a model to study the effects of alkaloids on insect gustation. Nine alkaloids, representing a wide range of structural types, were used. Their ability to stimulate chemosensory cells when presented in isolation and their ability to interfere with normal chemosensory processes were emphasized. None of the alkaloids stimulated chemosensory cells in a dose-dependent manner, although a few stimulated low-level activity from some cells. There was no evidence for a general deterrent receptor in these beetles. Some of the alkaloids had a marked inhibitory effect on normal chemosensory responses. Tomatine, solanine, papaverine, and sparteine significantly inhibited responses to amino acids (represented by GABA) while quinine and papaverine inhibited responses to sucrose. An attempt was made to correlate neurophysiological action of some alkaloids with their effects on feeding behavior. It was clear from this correlation that even a dramatic inhibition of sensory input by an alkaloid does not necessarily lead to measurable effects on behavior. The results are discussed in the context of current theories on the mode of action of alkaloids and other secondary plant compounds which may be involved in host recognition by phytophagous insects.     

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.     

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.     

Studies concerning charged nickel hydroxide electrodes IV. Reversible potentials in LiOH,NaOH, RbOH and CsOH

The variation of reversible potential E_r with log a_moh and has been studied for several nickel hydroxide/oxyhydroxide couples in various alkali hydroxides. Both activated and deactivated -phase couples show only a small dependence ofE _r with log_moh (or where known) in LiOH, NaOH, RbOH and CsOH electrolytes. The change in MOH content on oxidation/reduction is found to be about 0.1 mol MOH per two-electron transfer and is the same as found previously in KOH. These results confirm that the bulk oxidized -phase lattice is devoid of alkali cation although a small quantity may be adsorbed by the surface. On the other hand both activated and deactivated /-phase couples show a marked dependence of 0.45 mol MOH per two-electron transfer in LiOH, NaOH and RbOH (at concentrations > 0.5 m), also in good agreement with earlier data for KOH. On the basis of these results a general stoichiometry can be inferred for the -phase, namely M_0.32NiO₂ · 0.7H₂O where M=Li⁺, Na⁺, K⁺ or Rb⁺. Measurements imply that the Cs⁺ ion or the Rb⁺ ion at low concentration (<0.5 m) do not enter the interlayer structure of the -phase. This behaviour is thought to be related to the low Rb-O and Cs-O bond strengths afforded by the -phase structure.     

Alarm pheromones from the marine opisthobranchNavanax inermis

When molested, the marine opisthobranchNavanax inermis secretes into its slime trail, a bright yellow mixture of three major compounds and several closely related minor substances. Collectively, these compounds induce an avoidance-alarm response in a trail-followingNavanax at the concentration limits of 1 × 10^–5 M. The three major compounds have been isolated and identified as 10-(3-pyridyl)-3E,5E,7E,9E-decatetraen-2-one (navenone A), 10-phenyl-3E,5E,7E,9E-decatetraen-2-one (navenone B) and 10-(4-hydroxyphenyl)-3E,5E,7E,9E-decatetraen-2-one (navenone C). The minor constituents of the mixture are proposed as the 3Z,5Z,7E,9E-isomers and the 3-methyl homologs of navenones A and B. The navenones appear to be produced in a specialized gland referred to in earlier studies as the yellow gland and to communicate the presence of predators within the species.     

A study of the acidic and catalytic properties of pure and sulfated zirconia–titania and zirconia–silica mixed oxides

Protonated pyridine (PyH⁺) was not found on ZrO₂ (Z) or ZrO₂–TiO₂ (ZT), but was detected on sulfated oxides (ZS, ZTS) by IR spectroscopy. In contrast, ZrO₂–SiO₂ samples containing about 30–80 mol% ZrO₂ showed Brønsted acidity both in nonsulfated (ZS) and sulfated (ZSS) forms. The total acidity was determined by NH₃TPD. Introduction of sulfate ions increased the sitespecific catalytic activity (TOF) in the conversion of cyclopropane or nhexane. The effect of sulfate ions was more significant on samples rich in zirconia. Results suggest that Zr is homogeneously distributed in ZS samples rich in silica. Zirconiabound dimeric sulfate, generating strong acidity, could not be formed in these preparations due to the absence of fairly large ZrO₂ domains.     

Recovery and recrystallization of electrodeposited bright copper coatings at room temperature. II. X-ray investigation of primary recrystallization

X-ray investigations of the recrystallization processes occurring at room temperature in electrodeposited bright copper coatings were carried outin situ. As a result of the orientation transformation of the growth texture with 311, 111 and 110 components, a recrystallization texture with 100, 110 and 111 components was obtained. It was established that one of the factors which influence the microhardness of copper coatings is the orientation distribution of crystallites.     

Characteristics of Heterophase Radical Graft Polymerization of Methyl Methacrylate on Polymer Fibres

Graft copolymers with graft PMMA were synthesized using the Cu²⁺—H₂O₂ redox system. The conditions for obtaining graft PCA—PMMA and HC-PMMA of 40–60 composite composition with grafting efficiency at the 85% level are found. The effect of the polymer matrix on the kinetic and thermodynamic properties of graft polymerization of MMA is revealed. Possible schemes of the reactions of graft polymerization of MMA to polycaproamide and hydrated cellulose are proposed based on quantum chemical calculations of the enthalpy of formation of the graft copolymers.The research was conducted under MNTPP Project No. 203 Chemical Engineering (Section 2 General Chemical Engineering) in the scientific-industrial program Higher-Education Research on Priority Directions in Science and Engineering.__________Translated from Khimicheskie Volokna, No. 1) pp. 19–23, January–February, 2005.     

Deposition of nanocrystals on flat supports by spin-coating

Monodisperse particles can be evenly distributed over flat supports by spin-impregnation. In this way Cu precursors have been deposited onto Si wafers. The effects of the rotation frequency and the concentration of the impregnation solution have been investigated. The mean diameter of the deposited particles can be varied from several nanometers upto several micrometers as is shown by microscopy images. Spin-impregnation appears a useful tool to prepare well-defined flat model catalysts, which are readily accessible both to quantitative characterisation and to catalytic testing.