bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential behaviour of the survival stages of Nacobbus aberrans (Nemata: Pratylenchidae) under sub-optimal environments
Authors: Souza Ricardo , Baldwin James 
Published: July 2002

Abstract
The biology of Nacobbus aberrans is poorly understood, including the
behaviour of third and fourth stage juveniles (J3 and J4) under sub-optimal
environmental conditions. To assess the effect of such conditions on J3 and
J4, tomato plants infected by N. aberrans were grown under optimal
conditions, and then were submitted to sub-optimal day length and
temperature during the periods when J3 or J4 predominated in the population.
Even under optimal conditions, some J4 became quiescent. The suboptimal
conditions prevented both J3 and J4 moults, and affected nematode
development when optimal conditions were restored: the J3 immediately
moulted into J4, but many J4 remained quiescent and did not moult to the
adult stage. These unanticipated differences in how J3 and J4 endured
unfavourable conditions suggest that the latter stage is better adapted for
survival. Die Biologie von Nacobbus aberrans ist noch wenig bekannt,
einschliesslich des Verhaltens der Juvenilstadien drei und vier (J3 und J4)
unter suboptimalen Umweltbedingungen. Um die Wirkung solcher Bedingungen auf
J3 und J4 zu prüfen, wurden mit N. aberrans infizierte Tomatenpflanzen
zunächst unter optimalen Bedingungen gehalten und dann, wenn J3 und J4 in
der Population vorherrschten, suboptimalen Tageslängen und
Temperaturbedingungen unterworfen. Auch unter optimalen Bedingungen fielen
einige J4 in den Ruhezustand. Die suboptimalen Bedingungen verhinderten die
Häutungen von J3 und J4 und beeinträchtigten die Nematodenentwicklung auch
dann, wenn wieder optimale Bedingungen hergestellt wurden: die J3 häuteten
sich sofort zu J4, aber viele J4 verharrten im Ruhezustand und häuteten sich
nicht zu Adulten. Diese unerwarteten Unterschiede zwischen J3 und J4 in
bezug auf das Überstehen ungünstiger Bedingungen lassen vermuten, dass das
J4-Stadium besser für das Überleben angepasst ist.
Morphological variation between allopatric populations of Steinernema kraussei (Steiner, 1923)(Rhabditida: Steinernematidae)
Authors: Stock S. Patricia , Mrácek Zdenek , Webster John 
Published: July 2002

AbstractMorphometrics of four Canadian, three US and two European isolates representing distinct geographic populations of Steinernema kraussei (Steiner, 1923) were compared and analysed by multivariate analysis. A total of 540 individuals (270 males and 270 third-stage infective juveniles) representing the nine populations was measured. Fourteen morphometric variables were selected and subjected to principal component and canonical analyses. Results from both analyses indicate that there are morphological differences among the studied isolates, and that these differences are congruent with their geographic origin. The European isolates were shown to be distinctly different from the North American isolates. Within the North American isolates, the western isolates were distinguished from the eastern one (Parishville). No significant differences were observed between the two European isolates studied. Ont été comparées et étudiées par analyse multivariable les caractéristiques morphométriques de quatre isolats canadiens, trois isolats américains et deux isolats européens représentant des populations géographiques distinctes de Steinernema kraussei. Un total de 540 individus (270 mâles et 270 juvéniles infestants de troisième stade) représentant les neuf populations a été mesuré. Quatorze variables morphométriques ont été sélectionnées et soumises à des analyses en composantes principales et canonique. Les résultats des deux analyses montrent qu’il existe des différences morphologiques entre les isolats étudiés et que ces différences sont congruentes avec leur origine géographique. Les isolats européens sont apparus comme étant nettement différents des isolats nordaméricains. Dans le groupe des isolats nord-américains, les isolats de l’ouest ont été différenciés de celui de l’est (Parishville). Aucune différence significative n’a été observé entre les deux isolats européens étudiés.
The nematicidal effects of the bacteria Pseudomonas oryzihabitans and Xenorhabdus nematophilus on the root-knot nematode Meloidogyne javanica
Authors: Samaliev Harry , Andreoglou Fotini , Elawad Sami , Hague Nigel , Gowen Simon 
Published: July 2002

Abstract
In two laboratory experiments and one pot experiment the influence of the
bacterial symbionts Pseudomonas oryzihabitans from Steinernema abbasi and
Xenorhabdus nematophilus from S. carpocapsae on the root-knot nematode
Meloidogyne javanica was investigated. Exposure of egg masses of M. javanica
to the bacteria and their metabolites resulted in reduced hatching of second
stage juveniles (J2). J2 in contact with the bacteria and their metabolites
exhibited disorientation and convulsive movements, but when they were washed
and placed in fresh water, many regained normal movement. At dosages of 106
and 107 cells ml-1 mortality was 100% after 24 h exposure, Xenorhabdus being
more toxic than Pseudomonas. In soil X. nematophilus was ineffective but
P.oryzihabitans prevented invasion of J2 into tomato roots and there was
evidence that the bacterium or its metabolites interfered with nematode
development in galls. Overall, the results indicate that P.oryzihabitans may
provide a possible control strategy for root-knot nematodes. Action
nématicide des bactéries Pseudomonas oryzihabitans et Xenorhabdus
nematophilus sur le nématode Meloidogyne javanica - Les présentes
recherches, au travers de deux expériences au laboratoire et d'une troisième
en pots, ont concerné l'influence sur le nématode Meloidogyne javanica des
symbiontes bactériens Pseudomonas oryzihinabitans, provenant de Steinernema
abbasi, et Xenorhabdus nematophilus, de S. carpocapsae. L'exposition de
masses d'œufs de M. javanica aux bactéries et à leurs métabolites a provoqué
une diminution de l'éclosion des juvéniles de deuxième stade (J2). Les J2 en
contact avec les bactéries et leurs métabolites se sont montrés désorientés
et sujets à des mouvements convulsifs mais, après qu'ils aient été lavés et
placés dans une eau pure, bon nombre d'entre eux ont recouvré des mouvements
normaux. Aux doses de 106 et 107 cellules/ml-1 la mortalité était de 100%
après une exposition de 24 h, Xenorhabdus s'étant révélé plus toxique que
Pseudomonas . Dans le sol, Xenorhabdus s'est montré inefficace tandis que
Pseudomonas empêchait la pénétration des J2 dans les racines de tomate; de
plus, il semblerait évident que les bactéries ou leurs métabolites aient une
influence sur le développement des nématodes dans les galles. Dans
l'ensemble, les résultats indiquent que P.oryzihinabitans peut fournir une
éventuelle stratégie de contrôle envers les Meloidogyne.
Meloidogyne chitwoodi and M. fallax protein variation assessed by two-dimensional electrophoregram computed analysis
Authors: Tastet Christophe , Bossis Michel , Gauthier Jean-Pierre , Renault Lionel , Mugniery Didier 
Published: July 2002

AbstractThe variation of total soluble protein extracts from white adult females of seven Meloidogyne chitwoodi and three M. fallax isolates were studied using two dimensional gel electrophoresis (2-DGE). The 2-D protein profiles were compared with a computed analysis system. A synthetic image or 'master' was constructed from proteinic spots present in each isolate. The comparison of the two species allowed detection of qualitative and, to a lesser extent, quantitative variations. Among the 243 proteinic spots present on the master, we have identified 75 monomorphic spots for both species and nine discriminative proteins for each of the two species. In addition, two isoelectric point variants and two quantitative variants were observed. The similarity index and the genetic distances between the ten isolates were calculated on the basis of homologous polymorphic spots. Dendrograms were constructed according to the UPGMA method. Significance of the results from the phenetic study was assessed by bootstrap analysis. The results from the clustering analysis allowed differentiation between both species and showed intraspecific variation among the M. chitwoodi isolates equal to that among the M. fallax isolates. Variabilite proteique de Meloidogyne chitwoodi et M. fallax etudiee par analyse informatisee d'electrophoregrammes bidimensionnels - La variabilite d'extraits proteiques solubles totaux de femelles blanches adultes de sept isolats de Meloidogyne chitwoodi et trois de M. fallax a ete etudiee par electrophorese sur gel en deux dimensions (2-DGE). Les profils proteiques bidimensionels ont ete compares grace a un systeme d'analyse informatise. Une image synthetique, ou image de reference, a ete construite a partir des spots proteiques toujours observes dans chaque isolat. La comparaison des deux especes a permis de detecter des variations qualitatives et, dans une moindre mesure, quantitatives. Parmi les 243 taches proteiques presentes sur l'image de reference, ont ete identifies 75 polypeptides communs aux deux especes et neuf proteines discriminantes pour chacune des deux especes. De plus, deux variants de point isoelectrique et deux variants quantitatifs ont ete observes. Les indices de similarite et les distances genetiques entre les dix isolats ont ete etudies a partir des taches polymorphes homologues. Les dendrogrammes ont ete construits selon la methode UPGMA. La signification des resultats phenetiques a ete estimee par une analyse "bootstrap". Les resultats de l'analyse en grappes ont permis de differencier les deux especes et ont revele une variabilite intraspecifique similaire entre isolats de M. chitwoodi et isolats de M. fallax.
Dehydroxylation of Fe3+ , Mg-rich dioctahedral micas: (II) cation migration
Authors: Muller F. , Drits V. A. , Tsipursky S. I . , Plançon A. 
Published: July 2002

AbstractThe quantitative interpretation of the reflection intensities of the SAED patterns of glauconites reveals the mechanism of migration of the octahedral sheet cations during heating up to 750°C. It confirms that Mg2+ has a greater ability than Fe3+ to migrate from cis-to trans-sites, as previously found by means of XRD pattern modelling. For samples heated to 650°C, the two formerly vacant trans-sites in the base-centred unit-cell become occupied, but differently, which leads to a primitive unit-cell, and the cis-sites remain filled almost entirely by Fe3+ only. The cation migration occurs through the nearest shared edges in the [010] and [310] directions. The samples heated to 750°C reveal a base-centred super-cell with A = 3a and B = b. All Mg cations leave the cis-sites to occupy completely four of the six available trans-sites of the super-cell. Migration also occurs through the shared edges in the [010] and [310] directions. The primitive unit-cell is not an intermediate step in the migration process leading to the super-cell. The existence of additional satellites in the SAED patterns of some crystals heated to 750°C corresponds to the existence of antiphase domains with a 3b/2 width and an antiphase shift of a/2.
Clay mineral and organic diagenesis of the Lower Oligocene Schöneck Fishshale, western Austrian Molasse Basin
Authors: Gier S. 
Published: July 2002

AbstractThe ‘Fischschiefer formation’ has been identified as the likely source rock for petroleum in the western Molasse Basin of Austria. The investigated cores originate from different depths (1242 m to 4294 m) of the Fischschiefer horizon. The illitization observed in the <0.2 μm fraction proceeds slowly, probably because of the low geothermal gradient (3°C/100 m) in the Molasse Basin. The illite content in illite-smectite ranges from 30% (randomly ordered) for the shallowest sample to 65% (R0+R1 ordering) for the deepest sample. The oxygen index (OI) vs. hydrogen index (HI) plot implies type I to II kerogen for the organic matter. Vitrinite reflectance and Rock Eval parameters indicate an immature stage in the diagenesis of kerogen. Only the deepest sample (4294 m, 0.6% Rr) reaches the early oil window. There is a good correlation of the illitization trend of the mixed-layer mineral I-S and the organic maturity parameters.
Mechanical properties of North Sea Tertiary mudrocks: investigations by triaxial testing of side-wall cores
Authors: Wensaas L. , Aagaard P. , Berre T. , Roaldset E. 
Published: July 2002

AbstractIn the North Sea Tertiary section, wellbore instability problems are frequently reported in Palaeocene-Early Oligocene smectite-rich mudrocks. Analysis of the mechanical properties of these Tertiary mudrocks is generally hampered by the lack of suitable core material. This study represents an attempt to study the geomechanical behaviour of mudrocks by triaxial tests of side-wall cores obtained from the borehole wall. The tests performed include measuring the changes in pore pressure during shearing and undrained shear strength in specimens initially consolidated to in situ effective stress levels. The coefficients of permeability (kf), estimated from the consolidation time behaviour range from 2.6 x 10-11 to 2.4 x 10-12 m/s. The tested cores behaved like slightly overconsolidated to normally consolidated materials with an initial near constant volume (elastic behaviour) for low deviatoric load followed by an increasingly contractant behaviour approaching failure. Compared with results from onshore analogues, the strength properties of the investigated mudrocks appear to be related to their content of expandable clay minerals. A wellbore stability chart to forecast adequate drilling fluid pressures for future wells has been developed by the use of linear (Mohr-Coulomb) failure criteria based on the peak strength data. It is demonstrated that side-walt cores can provide satisfactory test materials for rock mechanical analysis, and their use may serve to improve our knowledge of the rock mechanical behaviour of typically troublesome mudrocks for which no conventional cores are available.
The origin and formation of clay minerals in soils: past, present and future perspectives
Authors: Wilson M. J. 
Published: July 2002

AbstractThe origin and formation of soil clay minerals, namely micas, vermiculites, smectites, chlorites and interlayered minerals, interstratified minerals and kaolin minerals, are broadly reviewed in the context of research over the past half century. In particular, the pioneer overviews of Millot, Pedro and Duchaufour in France and of Jackson in the USA, are considered in the light of selected examples from the huge volume of work that has since taken place on this topic. It is concluded that these early overviews may still be regarded as being generally valid, although it may be that too much emphasis has been placed upon transformation mechanisms and not enough upon neoformation processes. This review also highlights some of the many problems pertaining to the origin and formation of soil clays that remain to be resolved.
Clay formation and podzol development from postglacial moraines in Switzerland
Authors: Righi D. , Huber K. , Keller C. 
Published: July 2002

AbstractThe fine silt (2–5 μm) and fine clay (<0.1 μm) fractions from four acid soils developed from moraines of increasing age (80, 400, 3,000 and 6,500 years old) in Switzerland, were studied by X-ray diffraction and chemical analyses. The soil parent material is homogeneous at the four sites and the soils can be considered as forming a chronosequence of soil development leading to the formation of Podzols. Mineralogical evolution of silt-sized phyllosilicates and fine clay fractions follows different pathways according to their composition and the soil horizon in which they are located. Dioctahedral and trioctahedral minerals in the soil parent material were both weathered in the Bw and Bs horizons but the trioctahedral phase more strongly and faster than the dioctahedral one. Weathering products are mica-vermiculite mixed-layers, vermiculite and finally gibbsite and Fe oxy-hydroxides. Weathering of the trioctahedral fraction was faster in the eluvial A or E horizons than in the B horizons, being almost complete after 3,000 years of soil development. Appreciable weathering of the dioctahedral fraction occurs only in the eluvial horizons leading to the formation of mica-smectite mixed-layers and smectite. Although smectite has been reported in the E horizon of Podzols in different environments, the significant finding in this work is the presence of this mineral in soils developed from the same parent material. This supports the fact that smectite is the end- product of mica alteration in strongly leached and acidified E horizons of Podzols.
Geochemistry of mantle-related intermediate rocks from the Tibbit Hill volcanic suite, Quebec Appalachians
Authors: Abdel-Rahman Abdel-Fattah M. , Kumarapeli P. Stephen 
Published: July 2002

AbstractWe present a study on major and trace element geochemistry of some intermediate lithologies from the predominantly basaltic Tibbit Hill volcanic suite in the Humber Zone of the Quebec Appalachians. The intermediate rocks probably formed as lava flows in the volcanic sequence. Their presence shows that this rift-related, c. 554 Ma volcanic sequence is not bimodal (basaltic-comenditic) as previously thought, but consists of a spectrum of compositions ranging from mafic through intermediate to felsic lithologies. The entire volcanic sequence is poly-deformed and generally metamorphosed to greenschist facies conditions.The intermediate rocks of the Tibbit Hill Formation are trachyandesitic, trachytic and comenditic in composition, and exhibit a wide range of SiO2 content (52 to 68 wt.%). Mg is highly depleted in most samples. Variations of silica versus the alkalis show that most of the samples are alkaline in nature. The rocks display a tholeiitic trend on a standard AFM diagram.In general, the examined rocks also exhibit a wide range of Sr (15 to 174 ppm), Rb (0 to 156 ppm), Zr (155 to 899 ppm), Nb (18 to 123 ppm), and Y (18 to 94 ppm). The concentration of Hf and Ta are generally low (6.6–14.8 ppm, and 3.3–6.6 ppm, respectively), compared to those of Zr and Nb. Nevertheless, these rocks contain relatively high concentrations of the HFS elements, thus reflecting an enriched source. The suite is also relatively enriched in the rare earth elements (REE), and exhibits fractionated, subparallel REE pattems; the latter are generally uniform and conformable.Chemical features of these volcanic rocks are typical of those of anorogenic A1 type suites, related to hotspots, mantle plumes, or continental rift zones. This is consistent with earlier interpretation of volcanism associated with an Iapetan RRR triple junction, occurring shortly before the onset of seafloor spreading. At that stage of crustal evolution, alkaline to transitional basaltic magma pierced into the crust, and experienced fractionation to produce the liquids of intermediate composition. Rare earth element geochemical modelling supports the hypothesis that the most evolved composition for which REE data are available (comendite; 67.9 wt.% SiO2) was produced by 20% fractional crystallization of the least evolved trachyandesite (56.7 wt.% SiO2) of this intermediate volcanic assemblage.
Incorporation of ferric iron in CaSiO3 perovskite at high pressure
Authors: Wang Zhongwu , Yagi T. 
Published: July 2002

AbstractSynthetic andradite (Ca3Fe2Si3O12) has been compressed to loading pressures >21 GPa and heated to ∼1000°C by a YAG laser in a Diamond Anvil Cell (DAC). After quenching to room temperature, X-ray diffraction of the sample, still held at 21 GPa, showed that andradite had transformed to a cubic perovskite type polymorph with a = 3.460(4) Å. Upon decompression the perovskite phase transformed into an amorphous phase. The density of the perovskite polymorph (Ca3Fe2Si3O12) is ∼13.6% greater than that of isochemical andradite at 21 GPa. Ferric iron replaces Ca2+ and Si4+ in the perovskite structure (Fe3+ + Fe3+ = Si4+ + Ca2+), giving a formula unit: (Ca,Fe3+)(Si,Fe3+)O3. The new Fe3+-rich Ca-perovskite may provide new insight into the controls on the electrical conductivity of the lower mantle.
Palladium oxides in ultramafic complexes near Lavatrafo, Western Andriamena,
Madagascar
Authors: McDonald I. , Ohnenstetter D. , Ohnenstetter M. , Vaughan D. J. 
Published: July 2002

Abstract
Small (<2 km diameter), ultramafic intrusive complexes in the Andriamena
region of Madagascar contain zones with disseminated chromite and sulphides which
carry high concentrations of platinum-group elements (PGE). Assay of drill core
from one complex, designated UM2, revealed three zones showing consistently high
PGE grades. Mineralogical investigation of the UM2 core reveals that a small
number of low reflecting, Pd-bearing platinum-group minerals (PGM) are present —
always in association with a poorly characterized Pd stibio-arsenide
[Pd3(Sb,As)] phase — in the shallowest of the three zones.
Electron microprobe analysis of these PGM indicates the presence of oxygen and
that at least two species exist. The resulting stoichiometries suggest that at
least one species could be a hydrated form of palladinite
[PdO.(H2O)n]. The other phase could
be a hydroxide [Pd(OH)2] or a less strongly hydrated form of
palladinite. Textural evidence suggests that the Pd-O species formed via the
replacement of a precursor Pd-rich PGM, with only a limited removal of Pd, rather
than via precipitation of a Pd-O PGM from a fluid that was Pd-bearing. The limited
thermal stability of hydrated Pd oxides and the apparent restriction of the Pd-O
phases to a shallow zone which is affected by the seasonal movement of
groundwater, suggests that they may have formed at low temperatures via the
leaching and replacement of other elements from a precursor Pd-rich PGM by oxygen
and water during alternating water-saturated and dry conditions. If this is the
case, the water table interface might be another environment, in addition to the
surface, in which to look for the development of PGE oxides.
Unequilibrated assemblages of sulphide, metal and oxide in the fusion crusts
of the enstatite chondrite meteorites
Authors: Genge M. J. , Grady M. M. 
Published: July 2002

Abstract
The fusion crusts of meteorites form due to heating during atmospheric entry
and have mineralogies which are strongly influenced by changes in oxidation state.
We have studied the fusion crusts of the most reduced primitive meteorite group,
the enstatite chondrites, since they should demonstrate pronounced changes on
oxidation. The fusion crusts are dominated by highly unequilibrated assemblages of
sulphide, metal and oxide with compositions indicative of progressive oxidation by
the reaction with atmospheric oxygen. Troilite becomes depleted in Ti, Cr and Mn,
and enriched in Ni with increasing oxidation. Enrichments in the Ni-contents of
kamacite and depletions in Si-content also occur with oxidation, although
contemporaneous enrichments in Si within metal droplets occurs by partial melting.
Assemblages dominated by Fe-oxide are found within fusion crusts as reaction rims
on metal, as veins and within troilite-metal assemblages as droplets and formed by
oxidation of metal during heating. Despite the evidence for large increases in
redox state during heating, fusion crusts also contain lithophile sulphides
indicating a high degree of disequilibrium during the atmospheric reprocessing of
enstatite chondrite materials. Based on comparisons with experimental phase
relations, ablation rates of 0.08–0.25 cm s−1 are predicted
from the thermal gradients recorded in fusion crusts; these rates are broadly
similar to those suggested for other meteorite groups.