Search results for "CARBONATE"
showing 10 items of 920 documents
Energy balance related behaviour: Personal, home- and friend-related factors among schoolchildren in Europe studied in the ENERGY-project
2014
Published version of an article in the journal: PLoS One. Also available from the publisher: http://dx.doi.org/10.1371/journal.pone.0111775 Open Acces Objective: To design interventions that target energy balance-related behaviours, knowledge of primary schoolchildren’s perceptions regarding soft drink intake, fruit juice intake, breakfast consumption, TV viewing and physical activity (PA) is essential. The current study describes personal beliefs and attitudes, home- and friend-related variables regarding these behaviours across Europe. Design: Cross-sectional study in which personal, family and friend -related variables were assessed by validated questionnaires, and dichotomized as favour…
Secretin—cerulein test and fecal chymotrypsin concentration in children with intestinal giardiasis
1993
We studied six patients with giardiasis (five males, one female), median age 3.5 yr (range 1-11) and 12 healthy control subjects (10 males, 2 females), median age 3.5 yr (range 1-10). Intestinal biopsy and a contemporaneous secretin-cerulein test were performed in all patients, and fecal chymotrypsin was also assayed. Intestinal biopsy was normal in five of the six patients with giardiasis, whereas one of the six presented a partial atrophy of the intestinal villi. The secretin-cerulein test (1 CU/kg of secretin + 75 ng/kg of cerulein) did not show any significant difference between values in the outputs of chymotrypsin, lipase, phospholipase, and bicarbonate obtained in patients and in con…
Late Pleistocene aeolian dust provenances and wind direction changes reconstructed by heavy mineral analysis of the sediments of the Dehner dry maar …
2016
Abstract The study presents the results of a heavy mineral analysis from a 38 m long record of lacustrine Eifel maar sediments from a core section of the Dehner dry maar. The record encompasses the period from 29,000 to about 12,500 b2k. Statistical analyses enabled the distinction of local and regional source areas of aeolian material and revealed pronounced changes in the amounts of different heavy mineral species and corresponding changes in the grain size Index (GSI and CSI). The results indicate that during the early stages of MIS2 (39 to 30 m depth) aeolian sediments were supplied mostly from local sources. This period is characterized by low GSI and CSI ratios resulting from a reduce…
Stable, hydroxyl functional polycarbonates with glycerol side chains synthesized from CO(2) and isopropylidene(glyceryl glycidyl ether).
2012
A series of functional polycarbonates, poly((isopropylidene glyceryl glycidyl ether)-co-(glycidyl methyl ether) carbonate) (P((IGG-co-GME) C)) random copolymers with different fractions of 1,2-isopropylidene glyceryl glycidyl ether (IGG) units, is synthesized. After acidic hydrolysis of the acetal protecting groups, a new type of functional polycarbonate prepared directly from CO(2) and glycerol is obtained, namely poly((glyceryl glycerol)-co-(glycidyl methyl ether) carbonate) (P((GG-co-GME) C)). All hydroxyl functional samples exhibit monomodal molecular weight distributions with PDIs between 2.5 and 3.3 and M(n) between 12 000 and 25 000 g mol(-1) . Thermal properties reflect the amorphou…
Controlled Crystallization of CaCO3on Hyperbranched Polyglycerol Adsorbed to Self-Assembled Monolayers
2005
The formation of biominerals by living organisms is governed by the cooperation of soluble and insoluble macromolecules with peculiar interfacial properties. To date, most of the studies on mineralization processes involve model systems that only account for the existence of one organic matrix and thus disregard the interaction between the soluble and insoluble organic components that is crucial for a better understanding of the processes taking place at the inorganic-organic interface. We have set up a model system composed of a matrix surface, namely, a self-assembled monolayer (SAM), and a soluble component, hyperbranched polyglycerol. The model mineral calcium carbonate displays diverse…
Synthèse et formulation de résines photopolymérisables issues de la biomasse : application pour l'impression Braille
2014
The work of the PhD deals with the synthesis of polymerizable monomers derived from biomass, the study of their photopolymerization and the characterization of the resulting materials. The formulated monomers were tested in a printing method of Braille characters.The monomers were prepared in a two-steps reaction that is simple, economic and environmentally friendly. The first step comprised a reaction between glycerol derivatives (glycerol carbonate or glycidol) and fatty acids. In the second step, the obtained [alpha]-monoglycerides were functionalized to obtain photopolymerizable monomers. The different obtained monomers that bear (meth)acrylate and/or epoxy groups were photopolymerized …
Speciation of Copper in Enriched Agricultural Lime
2011
Agricultural liming materials are used to lower soil acidity and to improve microbial functionality and plant growth. A brownish colored agricultural lime was found to contain up to 180 mg kg ―1 Cu, an amount well above any fertilizing materials code threshold. The dark color of the milled material was due to ample black and brown dendrites consisting of the tectomanganate mineral romanechite (ideally (Ba,H 2 O) 2 (Mn 4+ ,Mn 3+ ) 5 O 10 ) and a mixture of the two nanocrystalline Fe oxides ferrihydrite and goethite. A four-step sequential extraction analysis of the lime powder was not sufficient to argue whether the Cu load was contained in the carbonate matrix or in the oxide dendrites, or,…
Boosting the methanolysis of polycarbonate by the synergy between ultrasound irradiation and task specific ionic liquids
2021
In an attempt to perform polycarbonate chemical recycling in a more sustainable way, we took into consideration the combined use of ultrasound irradiation and task specific ionic liquids. Towards this aim, the methanolysis of polycarbonate, into dimethylcarbonate and bisphenol A, was carried out in the presence of cholinium-based ionic liquids featuring anions derived from amino acids and other eco-friendly species. The target process was optimized in terms of both energy and material amounts as well as in terms of the nature of the catalysts used. The proposed protocol allowed high conversion and yields of bisphenol A to be obtained, under milder conditions compared to the ones so far repo…
Imidazolium and Potassium Hydrogen Carbonate Salts as Ecofriendly Organocatalysts for Oxazolidinone Synthesis
2016
International audience; Although oxazolidinones are valuable intermediate compounds for industrial applications, no synthetic method is suitable for their production on a large scale owing to the use of reagents/catalysts that are hazardous or toxic to human health or ecotoxic for the environment. In this manuscript, we describe new and efficient catalysts, that is, the nontoxic hydrogen carbonate anion in combination with a potassium or diisobutylimidazolium ([iBu(2)IM]) countercation, for the conversion of -amino alcohols into cyclic oxazolidinones in high yields of 69 to 90%. Depending on the catalytic conditions, both catalysts could be easily recovered from the crude reaction products …
Undecylenic acid: A tunable bio-based synthon for materials applications
2016
International audience; An undecylenic acid-based monoglyceride prepared from glycidol and undecylenic acid is used as suitable and tunable synthon for polymerization applications. Epoxidation and acrylation reactions lead to photopolymerizable monomers while transesterification with dimethyl carbonate, metathesis and aminolysis reactions provide access to polyhydroxyurethane-based materials. The successive intermediates were synthesized according to a green chemistry approach implicating solvent-less and catalyzed reactions, and were at each step fully characterized by infrared, 1H and 13C{1H} NMR spectroscopy, elemental analysis and mass spectrometry. Analyses of the resulting polymer mat…