Consulta: subjectFacets:"Dissolution"
Registros recuperados: 14
Data/hora: 09/06/2024 10:42:56

A benthic Si mass balance on the Congo margin: Origin of the 4000 m DSi anomaly and implications for the transfer of Si from land to ocean
Provedor de dados: 5
Autores: Ragueneau, O.; Regaudie-de-gioux, A.; Moriceau, B.; Gallinari, M.; Vangriesheim, Annick; Baurand, F.; Khripounoff, Alexis.
To elucidate the origin of the silicic acid (DSi) anomaly observed along the 4000 isobath on the Congo margin, we have established a benthic Si mass balance and performed direct measurements of biogenic silica (bSiO(2)) dissolution in the deep waters and in the sediments. Results strongly suggest that the anomaly originates from the sediments; the intensity of DSi recycling is consistent with the degradation of organic matter, as observed from Si:O-2 ratios in the benthic fluxes compared to that ratio observed in the anomalies. Strong imbalances, observed in both the Si and C mass balances, suggest that the biogenic matter that degrades and dissolves in these sediments near 4000 m does not come from pelagic sedimentation. It is probably not coming also...
Tipo: Text
Palavras-chave: Congo; Continental margin; Preservation; Dissolution; Biogenic silica.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-7410.pdf

Radiocarbon age offsets of foraminifera resulting from differential dissolution and fragmentation within the sedimentary bioturbated zone
Provedor de dados: 5
Autores: Barker, Stephen; Broecker, Wallace; Clark, Elizabeth; Hajdas, Irka.
Shells of coexisting species of planktonic foraminifera from the Ontong Java Plateau reveal radiocarbon age offsets of up to 2200 years. Similar offsets are found between fragments and whole shells of single species. Steady state modelling of dissolution and bioturbation within the sedimentary mixed layer predicts age differences of up to several kiloyears due to the interplay between differential dissolution and fragmentation of foraminifer shells and bioturbation. The observation that fragile foraminiferal shells are systematically older than those of more robust species is more difficult to explain. Mechanisms of chemical erosion, interface dissolution, and sediment redistribution are all apparently unable to explain this phenomenon. A possible solution...
Tipo: Text
Palavras-chave: Adiocarbon dating; Dissolution; Fragmentation.
Ano: 2007
URL: https://archimer.ifremer.fr/doc/00238/34943/33247.pdf

Trace element cartography of Globigerinoides ruber shells using particle-induced X-ray emission
Provedor de dados: 5
Autores: Gehlen, M; Bassinot, F; Beck, L; Khodja, H.
Micro particle-induced X-ray emission (PIXE) is a nondestructive elemental analysis technique that can be used to map the distribution of elements with a spatial resolution of +/-4 mum(2) and a penetration depth of +/-2 mum in a calcite matrix. To test its potential to improve our understanding of trace element distribution in foraminifera shells, we mapped the Mg distribution across individual chambers of the planktonic species Globigerinoides ruber. G. ruber shells were picked from equatorial Atlantic surface sediments (Sierra Leone Rise). They ranged from well-preserved to heavily dissolved tests. The mapping of trace elements across test chambers made it possible to discriminate between variability inherent to the shell material and heterogeneity...
Tipo: Text
Palavras-chave: Foraminifera; Mg/Ca; Dissolution; Trace elements; Instruments and techniques.
Ano: 2004
URL: https://archimer.ifremer.fr/doc/00228/33892/32319.pdf

Current CaCO3 dissolution at the seafloor caused by anthropogenic CO2
Provedor de dados: 5
Autores: Sulpis, Olivier; Boudreau, Bernard P.; Mucci, Alfonso; Jenkins, Chris; Trossman, David S.; Arbic, Brian K.; Key, Robert M.
Oceanic uptake of anthropogenic CO2 leads to decreased pH, carbonate ion concentration, and saturation state with respect to CaCO3 minerals, causing increased dissolution of these minerals at the deep seafloor. This additional dissolution will figure prominently in the neutralization of man-made CO2 . However, there has been no concerted assessment of the current extent of anthropogenic CaCO3 dissolution at the deep seafloor. Here, recent databases of bottom-water chemistry, benthic currents, and CaCO3 content of deep-sea sediments are combined with a rate model to derive the global distribution of benthic calcite dissolution rates and obtain primary confirmation of an anthropogenic component. By comparing preindustrial with present-day rates, we determine...
Tipo: Text
Palavras-chave: Ocean acidification; Seafloor; CaCO3; Dissolution; Anthropogenic CO2.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00675/78677/80887.pdf

The behavior of Al, Mn, Ba, Sr, REE and Th isotopes during in vitro degradation of large marine particles
Provedor de dados: 5
Autores: Arraes-mescoff, R; Roy-barman, M; Coppola, L; Souhaut, M; Tachikawa, K; Jeandel, C; Sempere, R; Yoro, C.
m) concentrations of Al, Sr, Ba, Mn, Rare Earth Elements (REE) and Th isotopes were determined over time. We obtain percentages of dissolution in agreement with the general knowledge about the solubility of these tracers: Th approximate to Al &lt; Heavy REE &lt; Light REE &lt; Mn &lt; Ba &lt; Sr. For Mn and Ce, precipitation/adsorption occurs at the end of the experiment probably due to their oxidation as insoluble oxides. Particulate residence time of the tracers ranged from less than 1 day to 10-14 days. During the experiment, biological activity has a control on the dissolution process through the remineralization of particulate organic carbon, In the 30 m experiment, the observed dissolution of aragonite indicates that the pH of the incubation solution...
Tipo: Text
Palavras-chave: Marine particles; Dissolution; Trace elements; Thorium isotopes; Western Mediterranean Sea.
Ano: 2001
URL: https://archimer.ifremer.fr/doc/00300/41128/40316.pdf

Comment on "Excess pore pressure resulting from methane hydrate dissociation in marine sediments: A theoretical approach" by Wenyue Xu and Leonid N. Germanovich - art. no. B02103
Provedor de dados: 5
Autores: Sultan, Nabil.
While it is well accepted that gas hydrate dissociation at the base of the Gas Hydrate Stability Zone (GHSZ) can generate high excess pore pressure and leads to sediment deformation, the consequence in terms of pore pressure of the dissolution of the gas hydrate at the top of the Gas Hydrate Occurrence Zone (GHOZ) remains neglected. The purpose of this comment on Xu and Germanovich [2006] article is to demonstrate that gas hydrate dissolution in the GHSZ may generate excess pore pressure and to point out the risk related to hydrate dissolution at the top of the GHOZ.
Tipo: Text
Palavras-chave: Pore pressure; Hydrate; Dissolution; Dissociation.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2318.pdf

Dissolution effects on the crystallography and Mg/Ca content of planktonic foraminifera Globorotalia tumida (Rotaliina) revealed by X-ray diffractometry
Provedor de dados: 5
Autores: Nouet, Julius; Bassinot, Franck.
Several authors suggested that the thinning, with increasing depth of deposition, of calcite X-ray diffractometry (XRD) peaks obtained on planktonic foraminifera tests resulted from the preferential removal of their poorly crystallized parts as dissolution increases. By deconvolving XRD peak (104) from Globorotalia tumida (surface sediments, Sierra Leone Rise depth transect), we show that the full width at midheight does not depend only upon crystallinity, but reflects also the chemical and structural heterogeneity of foraminifera tests, which results in closely spaced, individual (104) diffraction peaks corresponding to phases with slightly different Mg contents. G. tumida contains two calcite phases: a well crystallized, Mg-poor calcite and a poorly...
Tipo: Text
Palavras-chave: Dissolution; Foraminifera; X-ray diffraction; Crystallinity; Deconvolution.
Ano: 2007
URL: https://archimer.ifremer.fr/doc/00235/34626/32973.pdf

Cartel Dissolution with Effective Antitrust Policy
Provedor de dados: 31
Autores: Cai,   Xiaowei; Stiegert,   Kyle W.
Cartel operations still exist worldwide despite the recent development and enforcement of antitrust laws in scores of countries that previously had no such legal framework.  Since 1990, 283 international cartels were discovered by antitrust authorities around the world (Connor 2003). According to a 1990s' sample of U.S. Department of Justice and European Commission prosecuted cases, the discovered cartels operated in a wide variety of industries such as chemicals, metals, paper products, transportation, communication, food, textiles and services (OECD 2002). Were it not for the efforts to deter cartels by the antitrust agencies, there would likely have been many more such arrangements (Connor 2005).  The presence and societal impacts of domestic and...
Tipo: Conference Paper or Presentation
Palavras-chave: Cartel; Dissolution; Antitrust; Market Uncertainty; Industrial Organization.
Ano: 2010
URL: http://purl.umn.edu/61297

Iron oxides dynamics in a subtropical Brazilian Paleudult under long-term no-tillage management
Provedor de dados: 63
Autores: Inda,Alberto Vasconcellos; Torrent,José; Barrón,Vidal; Bayer,Cimélio; Fink,Jessé Rodrigo.
Replacing conventional tillage (CT) with no-tillage (NT) management alters the pedoenvironment and the rate of topsoil processes, with possible effects on dissolution processes associated with iron oxides and therefore soil mineralogy. This study aimed to determine the effect of NT on the content and distribution of types of iron oxides in a Rhodic Paleudult in southern Brazil. Soil samples were collected at eight depths within the 0.00-0.80 m layer under CT and NT in a long-term experiment (21 years). Mineralogical identification was conducted by X-ray diffraction (XRD), and the Fe content related to specific types of iron oxides determined by selective dissolution and diffuse-reflectance spectroscopy. Kaolinite, quartz, goethite, hematite, and maghemite...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Dissolution; Ferrihydrite; Hematite; Maghemite; Soil management.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162013000100008

Dissolution profile evaluation of solid pharmaceutical forms containing chloramphenicol marketed in Brazil
Provedor de dados: 52
Autores: Ferraz,Humberto Gomes; Carpentieri,Leticia Norma; Watanabe,Sayuri Pereira.
The dissolution profile for solid pharmaceutical forms containing chloramphenicol 250 mg available in Brazil was determined using a method from the American Pharmacopoeia (United States Pharmacopoeia, 2004) and then compared. Two different methods of dissolution profile comparison were used: ANOVA, and an independent model. Differences between the formulations were reflected in the dissolution profiles. The presence of metastable polymorphs or amorphous forms of chloramphenicol palmitate might be responsible for variations in the concentration of the drug observed within formulations.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Chloramphenicol; Dissolution; Polymorphism.
Ano: 2007
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132007000100007

Silymarin-Laden PVP-Nanocontainers Prepared Via the Electrospraying Technique for Improved Aqueous Solubility and Dissolution Rate
Provedor de dados: 52
Autores: Yousaf,Abid Mehmood; Malik,Usman Rashid; Shahzad,Yasser; Hussain,Talib; Khan,Ikram Ullah; Din,Fakhar Ud; Mahmood,Tariq; Ahsan,Hafiz Muhammad; Syed,Ahmed Shah; Akram,Muhammad Rouf.
Abstract The aim of the present research was to develop a silymarin-laden PVP-nanocontainer providing ameliorated aqueous solubility and dissolution of the drug. Several silymarin-laden formulations were formed with varying quantities of PVP and SDS via the solvent evaporation method using the electrospraying technique. The influence of the hydrophilic carriers on solubility and dissolution was explored. The solid-state characterization was carried out by particle-size analysis, PXRD, DSC, FTIR and SEM. All of the formulations demonstrated better solubility and dissolution than did silymarin plain powder. Both the SDS and PVP had positive effects on solubility and dissolution of silymarin in the aqueous media. An increased solubility was attained as the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Silymarin; Electrospraying; PVP-nanocontainers; Aqueous solubility; Dissolution.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132019000100612

Evaluating the discriminatory power of a dissolution assay for rosuvastatin calcium capsules: Solid-state properties and dissolution media
Provedor de dados: 60
Autores: Ângelo,Marilene Lopes; Ruela,André Luís Morais; Ferreira,Anna Clara Marques; Ramos,Marcus Vinicus de Faria; Montanari,Cristina Martiniano; Silva,Lucélia Magalhães da; Araújo,Magali Benjamim de.
We propose to evaluate the dissolution properties of rosuvastatin calcium (ROSC) capsules in different media to characterize the discriminatory power of the assay method. Dissolution assays were performed in media with different pH, and including the surfactant sodium dodecyl sulfate (SDS). Several immediate-release formulations were manufactured using the commercial raw material characterized as amorphous solid. The hydrophobic adjutant magnesium stearate was employed in some formulations due to its negative effect in the wettability and dissolution efficacy of solid dosages. These formulations showed the lower dissolution efficacy values in media without surfactant; however, when SDS was added to the medium, the dissolution efficacy increased, and the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Dissolution; Crystal polymorphism; Solid dosage form; X-ray powder diffractometry; Thermal analysis; Solubility.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502019000100527

Novel Eudragit® -based polymeric nanoparticles for sustained release of simvastatin
Provedor de dados: 60
Autores: Rodrigues,Deborah Fernandes; Couto,Renê Oliveira do; Sinisterra,Rubén Dario; Jensen,Carlos Eduardo de Matos.
This paper reports on the development of nanoparticles aiming at the in vitro controlled release of simvastatin (SVT). The nanoparticles were prepared by the nanoprecipitation method with polymers Eudragit® FS30D (EDGFS) or Eudragit® NE30D (EDGNE). EDGFS+SVT nanoparticles showed mean size of 148.8 nm and entrapment efficiency of 76.4%, whereas EDGNE+SVT nanoparticles showed mean size of 105.0 nm and entrapment efficiency of 103.2%. Infrared absorption spectra demonstrated that SVT incorporated into the polymer matrix, especially EDGNE. Similarly, the differential scanning calorimeter (DSC) curve presented no endothermic peak of fusion, indicating that the system is amorphous and the drug is not in the crystalline state. The maintenance of SVT in the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Simvastatin; Nanoparticles; Poly-methylmethacrylate; Dissolution; Drug delivery systems.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502020000100591

Design and evaluation of rhubarb total free anthraquinones oral colon-specific drug delivery granules to improve the purgative effect
Provedor de dados: 60
Autores: Wei,Hongwei; Chang,Jinhua; Liu,Pei; Li,Zhongsi; Miao,Guangxin; Liu,Xigang; Liu,Cuizhe; Zhang,Xiangrong.
Rhubarb is commonly used as a cathartic in Asian countries. However, researchers have devotedextensive concerns to the quality control and safety of rhubarb and traditional Chinese preparations composed of rhubarb due to the instable purgative effect and potential nephrotoxicity of anthraquinones. In this study, we aimed to prepare rhubarb total free anthraquinones (RTFA) oral colon-specific drug delivery granules (RTFA-OCDD-GN) to delivery anthraquinones to colon to produce purgative effect. RTFA-OCDD-GN were prepared using chitosan and Eudragit S100 through a double-layer coating process and the formulation was optimized. Continuous release studies were performed in a simulated gastric fluid (pH 1.2), followed by a small-intestinal fluid (pH 6.8) and a...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Rhubarb; Anthraquinones; Oral colon-specific drug delivery granules; Dissolution; Purgative activity.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502019000100500