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Current study aims to explore natural anti-phytopathogenic compounds for plant disease management. Syzygium cumini essential oil and its isolated compounds were screened for their antifungal assay against two phytopathogenic fungi, Rhizoctonia solani AG 4HG-III and Choanephora cucurbitarum . The chemical composition of oil the isolated oil was identified by gas chromatography and gas chromatography/mass spectrometry. Compounds such as 7-hydroxycalamenene, 7-acetoxycalamenene, 1-epi-cubenol, and α-terpineol showed an inhibition, ca. 95%, 80%, 76%, and 82%, respectively, against R . solani whereas 95%, 70%, 92%, and 100% against C . cucurbitarum in contact phase. In addition, high ocimene rich column fractions showed 70% and 87% inhibition against R . solani and C . cucurbitarum , respectively, in volatile phase. The findings of the present study suggest that the isolated 7-hydroxycalamenene, 7-acetoxycalamenene, 1-epi-cubenol, α-terpineol, and ( Z )-β- & ( E )-β-ocimene have a potential to be used as antifungal agents for the effective control of fungal diseases in medicinal plants. We report 7-acetoxycalamenene as novel compound from natural source for first time.

Twentyone genotypes of pyrethrum were studied for genetic variability. The highest genotypic and phenotypic coefficient of variations was recorded for cinerin II concentration at 55.53 and 57.27 followed by pyrethrin II at 48.97 and 48.99 lowest for total assay at 25.46 and 28.25, respectively. Six traits showed high heritability 94.01% to 99.90%, the highest being for pyrethrin II (99.90%). Pyrethrin I with total assay and pyrethrin II with jasmolin II were positively associated. Pyrethrin I and II made the highest direct and indirect contribution to total assay, hence may form a good selection criterion for flowers yields and qualitative traits.

The purpose of this investigation was to try to understand the antibacterial mechanism of L-(−)-usnic acid isolated for the first time from fruticose lichen Usnea subfloridana using clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentration (MIC) of L-(−)-usnic acid against the clinical isolates of MRSA and reference strain S. aureus MTCC-96 (SA-96) was in the range 25–50 μg/ml. Treatment of both reference and clinical strains (MRSA-ST 2071) with four-fold MIC concentrations (100–200 μg/ml) of L-(−)-usnic acid reduced the viability of cells without damaging the cell wall. However, the loss of 260 nm absorbing material and increase in propidium iodide uptake was observed in both of the strains. Similarly, a combined effect of L-(−)-usnic acid (25–50 μg/ml) and 7.5 % NaCl resulted in a reduced number of viable cells within 24 h in comparison to the control. These observations clearly indicate that L-(−)-usnic acid exerts its action by disruption of the bacterial membrane. Further, in vivo efficacy showed that L-(−)-usnic acid significantly (p < 0.001) lowered the microbial load of spleen at doses ranging from 1 to 5 mg/kg. Further, toxicity studies in infected mice at doses 20 times higher than the efficacious dose indicated L-(−)usnic acid to be safe. Paradoxically, L-(−)usnic acid exhibited changes in serum triglycerides, alkaline phosphatase (ALKP) and liver organ weight in the healthy mice administered with only 25 mg/kg body weight. The results obtained in this study showed that natural L-(−)-usnic acid exerts its antibacterial activity against MRSA by disruption of the cell membrane. Further, the natural L-(−)-usnic acid was found to be safe up to 100 mg/kg body weight, thereby, making it a probable candidate for treating S. aureus infections.

An unusual pattern of two bottom simulating reflections (BSRs) has been observed on seismic profiles from the continental margin offshore Western Norway. One of these reflections (BSR1) extends over large areas and has the characteristics of the classical BSR, that is a phase-reversed reflection from the base of the gas-hydrate stability zone. The second BSR (BSR0) occurs at approximately 70 ms two-way travel time beneath BSR1 and is here called a double BSR. The distribution of BSR0 is more local than that of BSR1 and it does not show the phase-reversal relative to the sea floor reflection that is characteristic for a BSR at the gas hydrate-free gas boundary. Results from an industrial borehole, from full waveform inversion of multichannel seismic data, from high-frequency ocean bottom hydrophones, and interpretation of seismic profiles, clearly indicate that BSR1 is reflected from the base of the methane hydrate equilibrium field. Results from full waveform inversion indicate that BSR0 corresponds to a 16–20 m zone where the velocity drops from about 1.8 km/s to a minimum of 1.4 km/s and then increases again. The low velocity of 1.4 km/s suggests the presence of free gas. The results support the hypothesis that BSR0 is a reflection from the base of gas hydrates containing hydrocarbons with a heavier molecular weight in addition to methane gas. Interference of reflections from the top and base of the low-velocity zone associated with BSR0 explain why BSR0 is not phase-reversed.

A simple reversed-phase liquid chromatographic method is developed for the simultaneous quantitation of the anticancerous drugs vincristine, vinblastine, and their precursors catharanthine and vindoline using a Merck Chromolith Performance reversed-phase high-performance liquid chromatography column. A better resolution is obtained in comparison with available particulate-type C18 columns. The column provides good reproducibility and peak symmetry. Chromatography is carried isocratically with a mobile phase of acetonitrile-0.1M phosphate buffer containing 0.5% glacial acetic acid (21:79, v/v; pH 3.5) at a flow rate of 1.2 mL/min and UV detection at 254 nm. Parameters such as linearity, limits of quantitation (LOQ) and detection (LOD), precision, accuracy, recovery, and robustness are studied. The method is selective and linear for alkaloid concentration in the range 0.25 microg-25 microg/mL. The LOQ and LOD are 25, 46, 56, and 32 microg/mL and 8, 14, 18, and 10 microg/mL, respectively. The results of accuracy studies are good. Values for coefficient of variation are 2.50, 1.82, 1.33, and 1.13, respectively. The percent recovery of the alkaloids was found to be 96%, 97%, 98%, and 98%, respectively. Peak purity and homogeneity of these compounds in plant extract is studied using a photodiode-array detector. This simple and rapid method of analysis is applied for the determination of these alkaloids in a large number of leaf extracts of Catharanthus roseus..

The essential oil of Melaleuca decora twigs has been obtained by hydrodistillation and analysed by GC-FID, GC/MS and (1)H-, (13)C-NMR experiments. The most abundant class of compounds in M. decora twig oil was phenylpropanoids represented by methyl eugenol (92.4%) as the most exclusive constituent. In terms of molecular diversity, phenylpropanoids dominate M. decora essential oil with low terpenoid (3.9%) proportion.

The mean time for 50% germination at 20 °C of 12 Indian wheat (Triticum aestivum) cultivars was nearly halved, from 51 h to 27 h, by soaking seed in water for 8 h prior to sowing. A delay of 24 h without further soaking, intended to simulate postponement of sowing, reduced the time saved by priming to 16%. Priming had no effect on final germination percentage. These results were used in the design of 275 on-farm, farmer-managed, participatory trials of seed priming in wheat during the 1997–98 and 1998–99 rabi (post-monsoon) seasons. In forty-one trials in tribal areas of Bihar and West Bengal states of India, seed priming gave a 13% grain yield advantage for farmers growing wheat in marginal areas with low levels of agricultural inputs. Mean benefits from seed priming of wheat in nine trials in Chitwan, Nepal were 17%. In high potential areas of Gujarat, India, 205 trials had higher rates of input use. Yield benefit from priming in these trials averaged only 5% but constituted an extra 200 kg ha−1 grain at little or no cost. In 20 trials on marginal land, with slightly saline irrigation water in Ahmadwala, Pakistan, an average yield increase of 36% was obtained using seed primed with a 0.2% gypsum solution. Collaborating farmers reported that priming wheat seed overnight resulted in faster, more complete emergence, more vigorous early growth, better tillering, earlier flowering, larger ears, earlier maturity and higher yields. In addition, many farmers also reported that foliage in primed plots was a darker shade of green than that in non-primed plots, suggesting that primed plants may have been using nitrogen more efficiently. Seed priming was popular with farmers, most of whom reported that they would prime wheat seed the following year. A survey in Gujarat in 1998–99 of 63 farmers who had tested priming in 1997–98 showed that, while 65% had primed some of their own seed, none had primed more than 50 kg, suggesting that there were practical difficulties in priming larger volumes of seed.

Seismological studies indicate that the inner core of Earth is anisotropic for compressional waves ( P waves), and has low shear wave ( S wave) velocity, and high seismic attenuation. Using an effective medium theory for composite materials, we show that the presence of a volume fraction of 3 to 10% liquid in the form of oblate spheroidal inclusions aligned in the equatorial plane between iron crystals is sufficient to explain the aforementioned seismic phenomena. Variation of S -wave velocity between the polar axis and equatorial plane is more sensitive to the addition of liquid than that of P waves. The liquid could arise from the presence of dendrites or a mixture of elements other than iron that exist in liquid form under inner-core conditions.

Summary Bottom simulating reflectors (BSRs) at the base of the hydrate stability zone are often observed in marine seismic reflection data. The compressional (P-)wave velocity structure of a BSR offshore Costa Rica was analysed by applying a full-waveform inversion technique. The resulting velocity profile indicates that the BSR is caused by a thin low-velocity layer, suggesting the presence of at least a small amount of free gas in the sediment pore space. In undisturbed sediment sections, BSRs offshore Costa Rica are observed over much of the continental margin. They frequently occur at shallow depths beneath the seafloor, usually ~ 100–400 m; at some locations BSRs appear to intersect the seafloor. This was interpreted as an indication that hydrates in the study area form partly from methane which was produced beneath the hydrate stability zone and migrated upwards. In the study area, the vertical movement of the hydrate stability zone relative to a given point in the sediment column, one of the potential factors leading to BSR formation or suppression, is controlled by both sedimentation and vertical tectonism. Both processes may hence play a role in controlling BSR distribution. BSRs are absent in areas which have been affected by slumping, except where the sedimentary section above the BSR remained intact during slumping. This indicates that slope failure can cause the destruction of BSRs.

Four compounds, stigmasterol, stigmasterol-β-D-glucopyranoside, luteolin-7-0-glucopyranoside and dotriacontanoic acid isolated from Vernonia cinerea have shown significant antifeedant activity based on percent feeding-deterrence and effective doses (ED50) against two lepidopterous insects, Spodoptera litura and Spilosoma obliqua. © 1998 John Wiley & Sons, Ltd.

The essential oil composition of Murraya exotica leaves and flowers from CIMAP Research Farm, Lucknow, were analysed by GC and GC-MS, which resulted in the identification of 56 and 72 constituents, representing 99.8% and 99.2% of the oils, respectively. The leaf oil showed ( £ )-nerolidol (27.8%), α-zingiberene (10.0%), β-caryophyllene (9.7%), (E,E) farnesol (8.9%) and δ-elemene (5.1%) as the major constituents, while the flower oil showed (E,E,E)-α-springene (23.8%), ( £ )-nerolidol (18.7%), (E,E) α-farnesene (13.2%), methyl palmitate (6.8%) and germacrene B (5.9%) as the major constituents.

In this work, cultivated Pimenta racemosa from North Indian plains was studied for its leaf volatile composition twice in year at two distinct seasons (spring and autumn) using GC-FID, enantio-GC-FID, GC/MS and 1H-, 13C-NMR and DEPT experiments. Phenylpropanoid was the abundant class of compounds represented by eugenol (72.9%) followed by chavicol (7.7%) whereas myrcene (9.6%) and limonene (3.8%) were identified as the most exclusive terpene constituents in spring collection. The autumn sample was recorded with highest eugenol (92.9%) proportion. Notably, presence of chavicol differentiates this oil from Pimenta dioica. An enantiomeric excess for (S)-(-)-limonene (41.1-45.3%) and (R)-(-)-linalool (86.7-89.9%) was recorded over (R)-(+)-limonene and (S)-(+)-linalool, respectively when separated on 6-tert-butyldimethylsilyl-2,3-diethyl-β-cyclodextrin chiral phase. Moreover, both the monoterpene derivatives occur as enantiomeric mixture in P. racemosa leaf essential oil.

Seismic reflection profiles across many continental margins have imaged bottom-simulating reflectors (BSRs) parallel to the seabed; these are often interpreted as the base of a zone in which methane hydrate "ice" is stable. Waveform inversion of seismic reflection data can be used to estimate from seismic data worldwide the velocity structure of a BSR and its thickness. A test of this method at a drill site of the Ocean Drilling Program predicts that sediment pores beneath the BSR contain free methane for approximately 30 meters. The hydrate and underlying gas represent a large global reservoir of methane, which may have economic importance and may influence global climate.

In the present study, we have synthesized copper/copper‐oxide nanoparticles by laser ablation of copper metal in aqueous solution of sodium dodecyl sulfate. The focused output of 1064 nm wavelength of pulsed Nd:YAG laser is used for ablation. The synthesized nanoparticles are characterized by UV‐visible absorption, X‐ray diffraction, transmission electron microscopy and Raman spectroscopy techniques. The synthesis of copper/copper oxide nanoparticles are confirmed by XRD and Raman studies. The possible mechanism of nanoparticle formation is also discussed.

Cadmium oxide nanoparticles are synthesized by pulsed laser ablation of cadmium metal in double distilled water, which are found stable for 24 hours. The sample is characterized by using UV‐VIS absorption, scanning electron microscopy, thermo gravimetric analysis, differential thermal analysis, X‐ray diffraction and fourier transform infrared techniques. XRD pattern shows that as synthesized nanopowder has maximum amount of the Cadmium hydroxide rather than its oxide, which converts into Cadmium oxide after annealing at 350° C.

Laser ablation of nickel nanoparticles suspended in double deionized water has been studied using Nd:YAG laser (355 nm) with energy 30 mJ/pulse. Produced nanoparticles are analyzed by UV‐visible absorption spectroscopy at certain interval (0, 20, 40, 60 minute). The particles are characterized by Transmission Electron Microscopy (TEM), and X‐ray Diffraction (XRD). TEM image shows that particles have crystal like structure and these particles are in the range of 20 nm to 50 nm.

A field crop of Lippia alba (Mill.) N.E. Br. LAC-2 genotype was raised through stem cuttings at Lucknow. The essential oil yields obtained upon hydrodistillation of leaves harvested between May 1998 and May 1999 varied from 0.6% to 0.8% on fresh weight basis. The GC and GC/MS analyses of the essential oils led to the identification of 15 compounds totalling 85% of the oil: the identified compounds included 4 monoterpene hydrocarbons (2%), 8 oxygenated monoterpenes (82%) and 3 sesquiterpene hydrocarbons (1%). The major constituent of the oil was linalool (65%). Copyright © 2000 John Wiley & Sons, Ltd.

Various extracts/fractions of the whole plant of Convolvulus microphyllus (Convolvulaceae) were bioassayed by the leaf disc method for feeding deterrence using Spilosoma obliqua Walker as a test insect. A new compound, db29-oxodotriacontanol isolated from the chloroform fraction of this plant was proved to be a potent antifeedant constituent under laboratory evaluations, whereas another compound, tetratriacontanoic acid was reported for the first time from this plant. The azadirachtin and crude neem extracts were taken as standard. A new compound (29-oxodotriacontanol) produced 85.74% inhibition at 8000 ppm concentration.

A system for the hydride generation atomic-absorption spectrophotometry of arsenic is described that uses ordinary boiling-tubes to hold the acidified samples into which sodium tetrahydroborate(III) solution is injected and the evolved hydrogen carries the generated arsine directly through the spectrophotometer nebuliser to a nitrogen-supported hydrogen flame. The total arsenic evolved is measured by integrating the absorbance for 16 s. Apart from transition metals of the cobalt, nickel and copper groups, the arsenic response appears to be insensitive to interferences, and the effects of these metals may be overcome by adding 0.5 g of thiourea to each sample. The limit of detection (95% confidence) is about 6 ng of arsenic and the reproducibility is about 1% for 0.5 µg of arsenic.