Search results for "CONST"
showing 10 items of 7706 documents
Performance-based characterization of recycled polymer modified asphalt mixture
2021
Due to the introduction of secondary materials, the asphalt mixtures to be designed and tested in our laboratories are constantly becoming much more complex than traditional asphalt mixtures making difficult to use conventional laboratory procedure and/or predict expected results. This study proposes a comprehensive characterization of asphalt mixture modified with recycled polymer compound by using both wet and dry process proposing adjustments to laboratory mixing and sample compaction procedure. Accordingly, three AC20 Hot Asphalt Mixture (HMA) were designed and their conventional and performance related properties were assessed by looking at a) Indirect Tensile test (ITS) a) moisture da…
Hydrothermal liquefaction of waste biomass in stirred reactors: One step forward to the integral valorization of municipal sludge
2020
Abstract Hydrothermal liquefaction (HTL) of municipal sludge (MS) was performed at 350 °C for 30 min (subcritical water) and at 400 °C for 0 min (supercritical water) at fixed kinetic severity (LogR0 = 8.9) in static and stirred batch reactors to study the effect of the flow regime on the energy recovery (ER) of the process and on the quality of the products. With adopted experimental procedures it was possible to reduce to less than 10% the yield of lost organic compounds, termed volatiles (VT), and to collect and quantify a liquid hydrocarbon fraction (HC) separated from the biocrude (BC). The highest value of the HC yield, 25% w/w, was obtained in supercritical conditions. The C content …
The impact of Pleurotus ostreatus on organic matter transformation processes.
2012
This study showed the effect of Pleurotus ostreatus on the external organic matter (OM) transformation processes. The kinetics of these changes were determined. The experiment was conducted as 42-day pot experiment done in four combinations (with four replications). The four combinations of different substrates were: (1) organic, (2) composted hay, (3) organic soil + composted hay, (4) organic soil + composted hay + lead. The study results showed that P. ostreatus had the ability to transform external OM as well as metal–organic complexes. These transformations were reflected in the constant rate of characterized changes and correlation coefficients. The study also indicated the direction o…
Tailoring the anionic function and the side chains of comb-like superplasticizers to improve their adsorption
2015
Nowadays admixtures and especially superplasticizers are unavoidable components of the concrete formulation. The high fluidizing efficiency of the comb-like superplasticizers must not overshadow their high costs. This study aims to determine the PCE structure parameters which influence their adsorption in order to enhance their resistance to sulfate competitive adsorption and thus minimize their dosage. The PCE adsorption has been studied on calcite and ettringite which are both surfaces representative of early hydrating cement. The effect of the POE side chain length and density and also of the PCE anionic function i.e. carboxylate, dicarboxylate or phosphate on the adsorption has been ana…
Environmentally relevant precursors of carbonyl sulfide in aquatic systems
1997
Seawater solutions of environmentally relevant organosulfur compounds, commercial humic acid (HA), and natural dissolved organic matter (DOM) were incubated with and without UV light in order to determine the carbonyl sulfide (COS) producing capabilities of these compounds. COS dark- and photo-production rate constants were determined for dilute solutions of the organosulfur compounds (μmol l−1) and HA/DOM (mg l−1). Dissolved COS was determined using a purge and cryogenic trap method followed by GC/FPD detection. COS was produced in considerable amounts both non-photochemically and photochemically from the reduced form of free acid of glutathione (GSH) and photochemically from cysteine (CYS…
Progress in polymeric material for hydrogen storage application in middle conditions
2014
Hydrogen sorption using a manganese oxide anchored to PEEK (Poly(ether-ether-keton)) matrix was studied. The functionalization process and the obtained results on hydrogen storage capability of the synthesized polymer are reported. The functionalised polymer was characterised by Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray diffraction and Volumetric Hydrogen sorption measurements. Different synthesis conditions in terms of precursor concentration and reaction time were used and the direct correlation between manganese oxide percentage and hydrogen storage capability was confirmed. In this way different powders were synthesised. It is assumed that the sample with 78 …
Novel acrylamido monomers with higher hydrophilicity and improved hydrolytic stability: II. Properties of N-acryloylaminopropanol
1996
The physico-chemical properties and the electrophoretic behavior of the novel set of monomers reported by (Simo-Alfonso et al., Electrophoresis 1996, 17, 723-731) have been evaluated. Of utmost importance was the combination of high hydrophilicity and extreme hydrolytic stability, most desired properties for, any electrophoretic matrix, especially for protein fractionation. One of these monomers (N-acryloylaminopropanol, AAP) was found indeed to be extremely hydrophilic (with a partition coefficient P of only 0.10, vs. P = 0.13 for N-acryloylaminoethoxyethanol and P = 0.20 for acrylamide) and to possess excellent stability to alkaline hydrolysis. Its hydrolysis constant (0.008 L mol-1 min-1…
Cyclic voltammetric analysis of pH-dependent complex formation equilibria in anion coordination chemistry
1995
A procedure to analyze pH-dependent complex formation equilibria from cyclic voltammetry is described. Application to adduct formation equilibria between [Fe(CN)(6)](4-) and [Fe(CN)(6)](3-) with different polyammonium receptors is discussed. Extension to the interaction of substrates such as ATP, NAD(+), NADP(+), and carboxylate ions with these receptors by means of competitive interaction with hexacyanoferrate(II) ion is presented.
Stopped-Flow and DFT Studies of Proton Transfer and Isomerization of 5-Amino-3-imino-1,2,6,7-tetracyano-3H-pyrrolizine and Its Related Base 2-(5-Amin…
2001
International audience; A complete kinetic study of pH-dependent isomerization of 5-amino-3-imino-1,2,6,7-tetracyano-3H-pyrrolizine (HL) and 2-(5-amino-3,4-dicyano-2H-pyrrol-2-ylidene)-1,1,2-tricyanoethanide (L‘-) in the pH range from −0.5 to +13 in aqueous solution, which spans over 7 orders of magnitude for the pseudo-first-order rates (log k from −4.8 to +2.5), has revealed for the first time the existence of the corresponding conjugate species L- and HL‘. The study has allowed the determination of the acid dissociation constants of HL (pKa) and HL‘ (pKa‘), as well as all of the individual forward and reverse isomerization rates of the acidic (HL/HL‘) and basic (L-/L‘-) forms. Although L…
Assembly of the Major Light-harvesting Chlorophyll-a/b Complex
2006
The major light-harvesting chlorophyll-a/b complex in most higher plants contains three carotenoids, lutein, neoxanthin, and violaxanthin. How these pigments are assembled into the complex during its biogenesis is largely unknown. Here we show that neoxanthin but not lutein can dissociate from the fully assembled complex. Its equilibrium binding constant in a detergent system (0.1% n-dodecyl-beta-D-maltoside) was determined to be > or = 10(6) m(-1). Neoxanthin insertion into light-harvesting chlorophyll-a/b complex prefolded from overexpressed apoprotein (Lhcb1*2 from Pisum sativum) in the presence of chlorophylls a, b, and lutein as the sole carotenoid is kinetically controlled by an activ…