Reaction of Cu(MeCN)
2(PPh
3)
2PF
6 with 1,2-bis(4-pyridyl)ethylene (bpe) produces either a layered hexagonal coordination network, Cu(bpe)
1.5(PPh
3)
∞
+
, if made from CH
2Cl
2/THF solutions, or a ...linear zigzag polymer, Cu(bpe)(PPh
3)
2
∞
+
, if crystallized using CHCl
3/THF. Both compounds include significant amounts of solvent as well as the non-coordinating anions within intercrystalline channels. In the former case, the reaction to remove one PPh
3 from the Cu(I) reagent complex competes effectively with the precipitation/crystallization step, whereas in the latter case, crystal growth occurs first.
Reaction of Cu(MeCN)
2(PPh
3)
2PF
6 with 1,2-bis(4-pyridyl)ethylene (bpe) produces either a layered hexagonal coordination network, Cu(bpe)
1.5(PPh
3)
2
∞
+
(see figure) if made from CH
2Cl
2/THF solutions, or a linear zigzag polymer, Cu(bpe)(PPh
3)
2
∞
+
, if crystallized using CHCl
3/THF. In the former case, the reaction to remove one PPh
3 from the Cu(I) reagent complex competes effectively with the precipitation/crystallization step, whereas in the latter case, crystal growth occurs first.
In Laboratoriumstests wurden an 19 Carabidenarten die Wirkungen von Bromophos ('Nexion') und Propoxur ('Unden') untersucht. Eine 100 % ige Mortalität zeigten sieben Arten (Bromophos) bzw. zwei Arten ...(Propoxur). In laboratory tests, the side-effects of bromophos ('Nexion') and propoxur ('Unden') were studied on 19 ground beetle species. A 100-percent mortality showed seven species (Bromophos) resp. two species (Propoxur).
In laboratory tests, the side-effects of bromophos ('Nexion') and propoxur ('Unden') were studied on 19 ground beetle species. A 100-percent mortality showed seven species (Bromophos) resp. two ...species (Propoxur)
Trypanites is a common boring in Ordovician hardgrounds of Estonia (Baltica). The depth of the sedimentary basin and sedimentation rates controlled the distribution of Trypanites. The trace-makers' ...community was diverse and changing over time. Three ichnospecies of Trypanites can be distinguished: T. sozialis, T. weisei and Trypanites isp. All three morphotypes can be recognized in the same hardground. It is impossible to distinguish between the different ichnospecies based only on the size of the boring aperture. The depth of early lithification of the seafloor determines the morphological variability seen in T. sozialis. The occurrence of elongated borings, such as T. weisei and Trypanites isp., is related to tropical environments, and their trace-makers strongly preferred substrates with a homogeneous and dense texture. The texture and available volume of hard substrate controls the ichnodiversity of Trypanites ichnospecies.
Chalk reservoirs are commonly modelled as dual-porosity systems, in which a very porous but low permeable matrix is intersected by highly permeable vugs and fractures from which oil and gas can be ...produced. The Gullfaks Field in the Norwegian North Sea contains such a reservoir, which is producing from Maastrichtian chalk in addition to the conventional Triassic and Jurassic siliciclastic reservoirs. However, in comparison to the prolific chalk fields in the southern North Sea (e.g. Ekofisk, Valhall), chalk reservoirs in the northern part (e.g. Oseberg and Gullfaks fields) experience challenged production due to reservoir presence and quality related to depositional facies and structural conditions. Analyses of cores from three wells in the Maastrichtian Shetland Group of the Gullfaks Field reveal that this interval is completely bioturbated during several stages, e.g. mottling with diffuse bioturbated texture in an early softground stage that became subsequently overprinted by more discrete burrows with active and passive fill and different rock properties during the stiffground and firmground stages of the ooze. A rich and moderately diverse trace-fossil assemblage consists of abundant Zoophycos, common Chondrites, Taenidium, Thalassinoides and Virgaichnus, and rare Nereites, Planolites, Spirophyton and Teichichnus. Ichnological features allow the differentiation of five recurrent ichnofabrics (Thalassinoides, Zoophycos, Chondrites, Nereites and Zoophycos-Taenidium ichnofabrics) with variable influence on porosity and permeability. The Thalassinoides ichnofabric in chalk has the highest impact on improving reservoir quality, whereas Zoophycos and partly Chondrites ichnofabrics, in marly chalk and chalky marlstone respectively, contribute to creating potential reservoir zones if burrow density is high enough. Thin-section analysis of the different ichnofabrics illustrates the negative or positive effect of burrows on porosity distribution, whereas micro-CT imaging reveals an intriguing system of partly open micro-burrows (e.g. Virgaichnus) within the matrix, which serves as source for porosity. This burrow porosity provides a connection in the matrix that hosts open vugs and fractures, thus improving oil production.
•Bioturbated chalk influences porosity distribution.•Timing of bioturbation and substrate consistency are crucial for porosity distribution.•Dual porosity systems with bioturbated matrix contribute to fracture connectivity.•Macro-burrows and micro-burrows revealed by means of micro-CT imaging.•Implications for producibility of chalk and other unconventional reservoirs.
The active ingredient imidacloprid used as seed dressing did not bring about rapid extermination of the species Sitobion avenae, Rhopalosiphum padi, and Metopolophium dirhodum under laboratory ...conditions. Imidacloprid exerted a prolonged effect (over 6 weeks after sowing) against wingless S. avenae adults, reducing the duration of survival, secretion of honeydew, and fertility of the pest in oats and winter barley. As a secondary effect, it led to the production of undifferentiated embryos and fewer larvae. In the sublethal range (no acute action on adults) the active ingredient achieved an almost constant high level of larval mortality. Despite the fact that feeding activity was in some substances interrupted many times, repellent and deterrent effects were excluded with the aid of a choice study. The efficacy is probably due to neurotoxic rather than to late antifeedant effects. Winged or wingless aphids transferred daily from treated plants (equivalent, in outdoor conditions, to ones which have migrated) were mostly able to infect a plant (generally the first one) with BYDV. In contrast to the controls, only a small percentage of individuals still alive after 24h were able to infect further plants. Extrapolation of the results to outdoor conditions shows that imidacloprid prevents secondary spread of aphids in particular, thus also preventing virus disease. Field studies in oats (summer 1991) and winter barley (autumn 1991) have confirmed the laboratory results, demonstrating the emerging cereals can be given prolonged protection from aphids and from infection with BYDV. In oats, an application rate of 105 g a.i./dt allowed control of aphids even during the flowering stage. Rhopalosiphum padi was reduced particularly drastically.
Sedimentology and paleoecology of omission or discontinuity surfaces in carbonate strata is well documented, but the geochemistry of such surfaces is poorly recognized. This work describes ...morphology, fabrics, geochemistry, and biota succession in omission levels from Middle Triassic (Muschelkalk) platformal carbonates in Upper Silesia, southern Poland. Three types of omission levels are distinguished: firmgrounds, hardgrounds, and intraformational conglomerates. (1) Firmgrounds are characterized by burrows of Balanoglossites triadicus. Some burrows are enclosed by a dark and/or (minor) bright diagenetic halo. The prevailing dark color, lower δ13C and δ18O ratios, and increased concentration of redox-sensitive elements (U, As, Mo, Cu, Zn, Pb, Ni) in the halos compared to the host micrite indicate a significant enrichment in organic matter, which most likely resulted from impregnation of the burrow walls with organic mucus from the burrowing organism, a process observed in modern burrows. The burrow walls were in contact with stagnant saline water (recorded by elevated 87Sr/86Sr), but were locally bleached by oxygenated fresh seawater pumped by the burrow producer. (2) Hardgrounds show encrustations of the bivalve Placunopsis ostracina and borings Trypanites weisei. In many hardgrounds, the uppermost 5-mm-thick layer has a different color and higher δ18O values than the underlying micrite. This heavier δ18O signal reflects a higher content of 18O-enriched early-marine microcrystalline cement precipitated from colder bottom seawater. (3) Intraformational conglomerates consist of flat pebbles derived from reworked firmgrounds and hardgrounds. Many pebbles contain the same encrustations and borings as observed in the hardgrounds, which occur on both sides of the clasts and mimic their shape, indicating that they were developed after pebble formation. All studied types of omission level are laterally discontinuous at some scale and are thus unsuitable for regional correlation.
•Firmground burrows are surrounded by dark and/or minor bright early diagenetic haloes.•Dark haloes are enriched in redox-sensitive elements and 12C and 87Sr stable isotopes.•These proxies suggest organic matter in burrow walls and stagnant water in burrows.•Hardground top surfaces show discoloration, bedding-parallel halo, and elevated δ18O.•This elevated δ18O implies early cementation by cold bottom seawater.
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