Search results for "solution"
showing 10 items of 5638 documents
Rod–coil copolymers from oligo(p-benzamide) foldamers
2007
Self assembling rod–coil copolymers were synthesized in which oligo(p-benzamide) rods up to the octamer were prepared via iterative solution synthesis employing the acid labile 2,4-dimethoxybenzyl amide protective group.
Temporal resolution and temporal transfer properties: gabaergic and cholinergic mechanisms.
2007
Temporal resolution is a basic property of the visual system and critically depends upon retinal temporal coding properties which are also of importance for directional coding. Whether the temporal coding properties for directional coding derive form inherent properties or critically depend upon the temporal coding mechanisms is unclear. Here, the influence of acetylcholine and GABA upon photopic temporal coding was investigated in goldfish, using flicker stimuli, in a behavioral and an electrophysiological (ERG) approach. The goldfish temporal resolution ability decreased from more than 90% correct choices at 20 Hz flicker frequency to about 65% at 45 Hz flicker frequency with a flicker fu…
Penetration of 2% cyclosporin eyedrops into human aqueous humour.
1989
The penetration into the eye and the systemic absorption of 2% cyclosporin eye drops were determined by polarisation immunofluorescent assay of cyclosporin in the aqueous humour and plasma of 30 patients at the time of cataract surgery. The results were then compared with the corresponding results after oral administration at a dosage of 5 mg/kg/day to three further patients. The maximum intraocular concentration (24 (SD 9) mg/l) was achieved four hours after topical administration. This level was slightly less than that found in aqueous humour (28 (SD 10) mg/l) 12 hours after systemic administration of the drug at a dosage of 5 mg/kg/day. Both these levels are below the minimum therapeutic…
Behavior of rare earth elements in an aquifer perturbed by CO2 injection: Environmental implications
2019
International audience; Three cubic-meters of CO2-saturated water was injected into a subsurface fractured aquifer in a post-mined area, using a push-pull test protocol. Groundwater samples were collected before and after CO2-injection to quantify geochemical changes. CO2-injection initially reduced the pH of water from 7.3 to 5.7, led to the enrichment of major ions (Ca2+, Mg2+, and alkalinity), and dissolved trace metals (including Fe, Mn, As, and Zn) in the groundwater. Rare earth elements (REE) and yttrium concentrations were also measured in these samples before and after CO2 perturbation, to evaluate their behavior. An enrichment of total Y plus REE (REY) occurred. REY fractionation w…
High‐Resolution Proxy Records From Two Simultaneously Grown Stalagmites From Zoolithencave (Southeastern Germany) and their Potential for Palaeoclima…
2020
Two small annually laminated stalagmites from Zoolithencave (southeastern Germany) grew between CE 1821 and 1970 (Zoo‐rez‐1) and CE 1835 and 1970 (Zoo‐rez‐2), respectively. Trace element concentrations were determined by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS). Samples for δ13C and δ18O analyses were micromilled on annual and subannual resolution. Soil and host rock samples were analyzed by X‐Ray Diffraction (XRD) and their elemental concentrations determined via inductively coupled plasma optical emission spectrometer (ICP‐OES). Trace element concentrations in the stalagmites show two groups in the principal component analyses: one with Mg, Ba, and Sr and an…
Complex-forming properties of peat humic acids from a raised bog profiles
2013
Abstract Humic substances (HS) belong to the most powerful complex-forming agents, significantly affecting major and trace element speciation in natural environment. Several authors have focused on humic–metal interactions, using differing methods and comparing humic substances on different sources. However, the intrinsic differences among the HS of different origin and the impact of humification degree on the complex formation between humic substances and metals have not received the necessary attention until now. The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids (HA) isolated from two well-characterized raised b…
Plio-Pleistocene geological evolution of the northern Sicily continental margin (southern Tyrrhenian Sea): new insights from high-resolution, multi-e…
2003
High-resolution seismic profiles were acquired in the north Sicily offshore region with an innovative, multi-tip sparker array which lacks ringing and has a base frequency around 600 Hz. The new data, combined with published data, suggest that intra-slope and extensional basins formed as a consequence of the late Miocene (?)–early Pliocene shortening and thrusting, and the middle (?)–late Pliocene continental rifting affecting the internal side of the Sicilian-Maghrebian chain. Early (?) Pleistocene to Holocene high-amplitude and high-frequency sea-level changes resulted in repeated sub-aerial exposure and flooding of the shelf, and the deposition of cyclically arranged hemipelagic and shel…
Volcanic CO_2 detection with a DFM/OPA-based lidar
2015
The DFM/OPA-based lidar BILLI was used to investigate the volcanic plume released by the hydrothermal vent of Pisciarelli, in the Campi Flegrei volcano. BILLI remotely measured CO2 concentrations in cross-sections of the nearvent plume using the differential absorption technique. To our knowledge, this is the first example of lidar-based measurement of volcanic CO2 . The spatial resolution was 1.5 m and the temporal resolution 20 s. © 2015 Optical Society of America.
Mapping lava flows at Etna Volcano using Google Earth Engine, open-access satellite data, and machine learning
2021
Estimating eruptive parameters is fundamental to assess the volcanic hazards posed to the community living at the edge of active volcanoes. Here, we analyzed satellite remote sensing data by using machine learning unsupervised and supervised techniques and analytical approaches, i.e., mathematical-physics and statistics formulations, to map lava flows emitted during the long sequences of short-lived, violent eruptions occurred at Etna volcano between December 2020 and March 2021. Satellite observations allowed to follow the evolution of eruptions thanks to their capability to survey large areas with frequent revisit time and accurate spatial resolution. We quantified the areal coverage of l…
Hydraulic properties of fault zones in porous carbonates, examples from central and southern Italy
2016
We present the results of in situ permeability measurements performed, using a portable field permeameter, on normal and strike-slip fault zones that crosscut high-porosity carbonate grainstones. The measurement sites expose in the Cretaceous Orfento Formation of the Majella Mountain (Abruzzo, Italy), and the Lower Pleistocene deposits of the Favignana Island (Sicily, Italy). Nine small-displacement, compactive shear banding-based fault zones have been tested in the field. The fault offset ranges between 10 and 200 centimeters. The acquired permeability data indicate a two orders of magnitude decrease of porosity and permeability from the host rock to the cataclastic fault cores. A clear de…