Search results for "chemistry [Water]"
showing 10 items of 2369 documents
U-Pb zircon geochronology and phase equilibria modelling of a mafi c eclogite from the Sumdo complex of south-east Tibet: insights into prograde zirc…
2017
Abstract The Sumdo complex is a Permian–Triassic eclogitic metamorphic belt in south-east Tibet, which marks the location of a suture zone that separates the northern and southern Lhasa terranes. An integrated geochronological and petrological study of a mafic eclogite from the complex has constrained its tectonometamorphic history and provides a case study of zircon growth in eclogite as a product of prograde dissolution–precipitation. In situ U–Pb geochronology indicates that the eclogite contains a single population of zircon with a crystallisation age of 273.6 ± 2.8 Ma. The morphology and chemistry of the zircon grains are consistent with growth by dissolution–precipitation of protolith…
Design and experimental validation of a generic model for combinatorial assembly of DNA tiles into 1D-structures.
2010
Abstract Background Quantitative modeling of the self-assembly of DNA tiles leading either to defined end-products or distribution of biopolymers is of practical importance for biotechnology and synthetic biology. Methods The combinatorial process describing tile assembly was implemented into a generic algorithm allowing quantitative description of the population of significant species accumulating during the reaction course. Experimental formation and characterization by optical and electrophoresis approaches of copolymers resulting from the self-assembly of a limited number of half-complementary tiles were used to define and validate generic rules allowing definition of model parameters. …
Coastal New Particle Formation: A Review of the Current State-Of-The-Art
2005
Environmental Context.Atmospheric aerosols play an important role in determining the earth’s radiative budget, climate change and air quality levels. Much effort has been spent on quantifying the impact of aerosols on climate change; however, the largest gap in our knowledge relates to quantifying natural aerosol systems and the new particle formation process associated with these systems. The marine aerosol system is of particular interest due to the 70% ocean coverage of the earth’s surface. Coastal new particle formation events are though to be more frequent and of stronger intensity compared with open ocean events and thus have been studied in detail to identify possible processes lead…
Quantification of Coastal New Ultra-Fine Particles Formation from In situ and Chamber Measurements during the BIOFLUX Campaign
2005
Environmental Context. Secondary processes leading to the production of ultra-fine particles by nucle- ation are still poorly understood. A fraction of new particles formed can grow into radiatively active sizes, where they can directly scatter incoming solar radiation and, if partly water soluble, contribute to the cloud condensation nuclei population. New particle formation events have been frequently observed at the Mace Head Atmospheric Research Station (western Ireland), under low tide and sunny conditions, leading to the hypothesis that new particles are formed from iodo-species emitted from macroalgae. Abstract. New particle formation processes were studied during the BIOFLUX campaig…
Age, lithology and structural evolution of the c. 3.53 Ga Theespruit Formation in the Tjakastad area, southwestern Barberton Greenstone Belt, South A…
2009
Abstract A field and petrographic re-assessment of rocks from the Theespruit Formation near Tjakastad, southwestern Barberton Greenstone Belt, is combined with new zircon U–Pb ages and whole-rock Sm–Nd isotopic results to reveal several important inconsistencies with a previous thrust-accretion model for this area. It was found that faults previously interpreted as ‘thrusts’ are extensional, ‘thrust slices of basement orthogneiss’ are little deformed quartz-feldspar porphyries or sheared felsic volcaniclastic sedimentary rocks, and ‘sedimentary diamictites’ are felsic agglomerates. These observations, combined with consistent facing directions of bedding, the recognition of distinct stratig…
A hybrid genetic algorithm with local search
2001
Abstract A hybrid genetic algorithm with internal local search was developed for optimisations involving continuous variables. The reproduction probabilities were enhanced using the fitness values obtained when a local method was applied to each individual in the population. These estimations are more realistic, since consider not the apparent but the hidden, latent quality of each individual. The information gathered in the local search was also used to build an auxiliary population recording the successfully enhanced individuals, which allowed to detect the convergence and self-adapt the search limits. The size of this auxiliary population was kept constant by a cluster analysis strategy.…
Ancient xenocrystic zircon in young volcanic rocks of the southern Lesser Antilles island arc
2017
Abstract The Lesser Antilles arc is one of the best global examples in which to examine the effects of the involvement of subducted sediment and crustal assimilation in the generation of arc crust. Most of the zircon recovered in our study of igneous and volcaniclastic rocks from Grenada and Carriacou (part of the Grenadines chain) is younger than 2 Ma. Within some late Paleogene to Neogene (~ 34–0.2 Ma) lavas and volcaniclastic sediments however, there are Paleozoic to Paleoarchean (~ 250–3469 Ma) xenocrysts, and Late Jurassic to Precambrian zircon (~ 158–2667 Ma) are found in beach and river sands. The trace element characteristics of zircon clearly differentiate between different types o…
The use of shallow dripwater as an isotopic marker of seepage in karst areas: A comparison between Western Sicily (Italy) and the Harz Mountains (Ger…
2013
Abstract The isotopic signature of slow-flowing dripwater collected in caves located in Western Sicily (Italy) was determined for evaluating its possible use as an isotopic tracer of the local groundwater recharge. These spot measures were compared with a longer series of local rain and spring compositions and with other samples taken, under different hydrogeological conditions, in caves of the Harz Mountains (Northern Germany). The slow flowing dripwater from Sicily showed δ 18 O/δD ratios similar to those of local rain and groundwater, demonstrating that these three are all parent waters. A parallel similarity was found in the vertical isotopic gradient (Δδ 18 O) of the three groups of wa…
Acoustic, myoelectric, and aerodynamic parameters of euphonic and dysphonic voices: a systematic review of clinical studies
2021
Background: At present, there is no clinical consensus on the concept of normal and dysphonic voices. For many years, the establishment of a consensus on the terminology related to normal and pathological voices has been studied, in order to facilitate the communication between professionals in the field of the voice. Aim: systematically review the literature to compare and learn more precisely the measurable and objective characteristics of the acoustic, aerodynamic and surface electromyographic parameters of the normal and dysphonic voices. Methods: The PRISMA 2020 methodology was used as a review protocol together with the PICO procedure to answer the research question through six databa…
Application of Electronic Nose for Evaluation of Wastewater Treatment Process Effects at Full-Scale WWTP
2019
This paper presents the results of studies aiming at the assessment and classification of wastewater using an electronic nose. During the experiment, an attempt was made to classify the medium based on an analysis of signals from a gas sensor array, the intensity of which depended on the levels of volatile compounds in the headspace gas mixture above the wastewater table. The research involved samples collected from the mechanical and biological treatment devices of a full-scale wastewater treatment plant (WWTP), as well as wastewater analysis. The measurements were carried out with a metal-oxide-semiconductor (MOS) gas sensor array, when coupled with a computing unit (e.g., a computer with…