Search results for "trap"
showing 10 items of 2144 documents
Unexpected Scholl Reaction of 6,7,13,14-Tetraarylbenzo[k]tetraphene: Selective Formation of Five-Membered Rings in Polycyclic Aromatic Hydrocarbons
2016
Cyclodehydrogenation is a versatile reaction that has enabled the syntheses of numerous polycyclic aromatic hydrocarbons (PAHs). We now describe a unique Scholl reaction of 6,7,13,14-tetraarylbenzo[k]tetraphene, which "unexpectedly" forms five-membered rings accompanying highly selective 1,2-shift of aryl groups. The geometric and optoelectronic nature of the resulting bistetracene analogue with five-membered rings is comprehensively investigated by single-crystal X-ray, NMR, UV-vis absorption, and cyclic voltammetry analyses. Furthermore, a possible mechanism is proposed to account for the selective five-membered-ring formation with the rearrangement of the aryl groups, which can be ration…
Electrochemical and spectroscopic studies of poly(diethoxyphosphoryl)porphyrins
2011
Abstract The synthesis and electrochemical characterization of two related series of porphyrins bearing diethoxyphosphoryl groups are reported. One group of compounds is represented as (T( p -R)PP)M where R = phos = P(O)(OEt) 2 and M = Zn(II) or H 2 while the other is represented as (di( p -R)Pdi(phos)P)M where R = P(O)(OEt) 2 , H or CH 3 and M = Zn(II) or H 2 . Each porphyrin was investigated by electrochemistry and thin-layer spectroelectrochemistry in CH 2 Cl 2 , CDCl 3 , CHCl 3 or PhCN containing tetra- n -butylammonium perchlorate (TBAP) as supporting electrolyte. The highly electron-withdrawing P(O)(OEt) 2 groups lead to easier reductions and harder oxidations than the two comparison …
Application of Rigidity-Controlled Supramolecular Affinity Materials for the Gravimetric Detection of Hazardous and Illicit Compounds.
2016
The combination of an (-)-isosteviol-derived building block and 9,9'-spirobifluorene or tetraphenylmethane generated highly potent new affinity materials for the detection of volatile organic compounds (VOCs). Comparison of their affinity behaviour with different core structures showed remarkable influence on selectivity and sensitivity due to structural rigidity and their pre-organization. Their unique supramolecular properties were investigated in an affinity assay using high fundamental frequency quartz crystal microbalances.
Middle Jurassic–Early Cretaceous tectono-sedimentary evolution of the southwestern Iberian Basin (central Spain): Major palaeogeographical changes in…
2019
Abstract The Middle Jurassic-Early Cretaceous tectono-sedimentary evolution of the southwestern part of the intraplate Iberian Basin (Spain) was mostly controlled by the Alto Tajo-Montes Universales (ATMU) and Landete-Teruel (LT) faults. During the Middle Jurassic, the ATMU fault separated a western area dominated by shallow marine carbonates, and an eastern area with open marine facies. During the Bathonian-Callovian, the area located to the west of the ATMU fault and north of the LT fault (Cuenca domain) was progressively exposed, and remained uplifted until the late Barremian. A widespread unconformity with a variable gap around the Callovian to mid-Oxfordian has been related to the onse…
Slender Ca II H fibrils mapping magnetic fields in the low solar chromosphere
2017
S. Jafarzadeh et. al.
A new ichnofauna from the Permian of the Zat Valley in the Marrakech High Atlas of Morocco
2020
Abstract A new ichnofauna from the Permian of Morocco is described in details: it is the first Palaeozoic ichnofauna from the Zat Valley in Marrakech High Atlas. The new tracksite was found in the Tighdouine region, in the middle-upper Permian of the Cham-el-Houa Siltstone Formation. An abundant and diverse ichnoassemblage composed of both protostomian (probably arthropods and annelids) traces and vertebrate tracks is recorded. The presence of protostomian burrows and traceways, associated with tetrapod tracks corresponds to the Scoyenia ichnofacies. Protostomian traces are ascribed to Diplichnites gouldi, Diplopodichnus biformis, Scoyenia cf. gracilis and Spongeliomorpha carlsbergi. Tetrap…
Cretaceous ultrapotassic magmatism from the Sava-Vardar Zone of the Balkans
2020
Highlights • Geochemically diverse Late Cretaceous small-volume magmatism in the Sava-Vardar Zone. • Late Cretaceous ultrapotassic lava, equivalent of minette and kersantite. • Magma derivation from a LREE and K enriched, garnet-bearing anciently metasomatized mantle source. • Magmatism occurred either in a fore-arc setting or is associated with transtensional tectonics. Abstract Late Cretaceous global plate reorganization associated with the inception of counterclockwise rotation of Africa relative to Europe initiated in the Balkan region small-volume magmatism of diverse geochemical signature along the enigmatic Sava-Vardar Zone. We study a Late Cretaceous lamprophyric sill in Ripanj vill…
A Plot-scale uncertainty analysis of saturated hydraulic conductivity of a clay soil
2021
Abstract Simulating soil hydrological processes at the plot or field scale requires using spatially representative values of the saturated soil hydraulic conductivity, Ks. Sampling campaigns should yield a reliable mean of Ks with a sustainable workload since measuring Ks at many points is challenging. Uncertainty analysis can be used to determine the lowest number of measurements that yield a mean Ks value with a specified accuracy level. Potential and limitations of this analysis were tested in this investigation for different extents of the sampled area and sampling densities. A clay soil was sampled intensively on two plots (plot area = 44 m2), two dates and using both small (0.15 m in …
Chemical speciation of Fe, Mn, Pb, Zn, Cd, Cu, Co, Ni and Cr in the suspended particulate matter off the Mejerda River Delta (Gulf of Tunis, Tunisia)
2016
International audience; Fluxes of suspended particulate matter (SPM) and their associated metals were performed off the Mejerda River Delta during both the wet (March) and the dry (July) seasons in 2012, using sediment traps at study stations at depths of 10, 20 and 40 m. Fluxes nearest to the Mejerda outlet were more significant, especially during winter (36 g m−2 day−1), but dissipated further offshore, 24.5–6 g m−2 day−1 at the 20 m and 21.8–4.8 g m−2 day−1 at the 40 m stations. Many variations observed in seasonal and spatial metal fluxes are similar to those of SPM, in particular Pb and Zn, probably because they are associated with the mining activity characteristic of the Mejerda catc…
Strongly SiO2-undersaturated, CaO-rich kamafugitic Pleistocene magmatism in Central Italy (San Venanzo volcanic complex) and the role of shallow dept…
2020
The Pleistocene (~460–265 ka) San Venanzo volcanic complex belongs to the IAP (Intra-Apennine Province) in central Italy, which comprises at least four small Pleistocene monogenetic volcanoes plus several unrooted pyroclastic deposits with peculiar mineralogical and whole-rock chemical compositions. San Venanzo products are strongly SiO2-undersaturated, CaO- and MgO-rich and show ultrapotassic serial character. The relatively common occurrence of calcite in the pyroclastic rocks and the overall high CaO content are interpreted in literature as primary mineral. The main rock facies at San Venanzo are calcite-rich scoria and lapilli tuffs, with minor massive lava flows, and a rare pegma…