Search results for "quantitative"
showing 10 items of 2409 documents
An on-line system for preconcentration and determination of lead in wine samples by FAAS
2002
A flow injection method has been developed for the direct determination of free available Pb(II) and total Pb content in wine samples. The method is based on the chemical sorption of Pb(II), from pH 7 buffered solutions, on a packed polyurethane foam column, modified by addition of 2-(2-benzothiazolylazo)-p-cresol (BTAC). After this step, lead was directly eluted with a stream of 0.1 mol l(-1) HCl into an air C(2)H(2) flame in which lead was determined by atomic absorption spectrometry. Total lead was analyzed after sample digestion with nitric acid and hydrogen peroxide, being free available lead determined by direct sample on-line preconcentration and elution. The method provides a limit …
Date-rape evidence through fast determination of γ-butyrolactone in adulterated beverages.
2021
Abstract An infrared spectroscopy (IR) based methodology has been developed to determine γ-butyrolactone (GBL) in adulterated beverages. The proposed method permits the direct screening of GBL in beverages and involves a minimum sample treatment requiring less than 2 min for quantitative determination of GBL. Sensitivity of IR method was improved by using liquid-liquid extraction (LLE) providing detection limits of 0.023 mg g−1. Accuracy of the proposed methodology was evaluated through the analysis of soft beverages and alcoholic cocktails spiked with GBL at concentration levels ranging from 0.075 to 10 mg g−1 providing recovery values from 91 to 100%. GBL was determined in twelve blind-sp…
La cultura ci salverà? Processi di touristification a base culturale nel centro storico di Palermo
2023
Negli ultimi tre decenni la cultura ha avuto un ruolo chiave nella costruzione delle politiche urbane, divenendo uno strumento decisivo nella definizione delle strategie di sviluppo economico e nell’accesso alla competizione globale che caratterizzano l’attuale regime di neoliberismo urbano (Miles e Paddison 2005). Anche nel sud Europa la cosiddetta rigenerazione a base culturale ha rappresentato e continua ancora oggi a rappresentare una vera e propria ortodossia urbana, che trova nel turismo tanto una ragione di esistenza quanto un campo di attuazione. In particolare, negli ultimi anni i centri storici di molte città sudeuropee sono stati oggetto di trasformazioni profonde in cui pratiche…
Resonant activation in polymer translocation: new insights into the escape dynamics of molecules driven by an oscillating field
2010
The translocation of molecules across cellular membranes or through synthetic nanopores is strongly affected by thermal fluctuations. In this work we study how the dynamics of a polymer in a noisy environment changes when the translocation process is driven by an oscillating electric field. An improved version of the Rouse model for a flexible polymer has been adopted to mimic the molecular dynamics, by taking into account the harmonic interactions between adjacent monomers and the excluded-volume effect by introducing a Lennard–Jones potential between all beads. A bending recoil torque has also been included in our model. The polymer dynamics is simulated in a two-dimensional domain by num…
Translocation time of periodically forced polymer chains.
2010
6 páginas, 11 figuras.-- PACS number(s): 36.20.-r, 05.40.-a, 87.15.A-, 87.10.-e
Spinodal lines and Flory-Huggins free-energies for solutions of human hemoglobins HbS and HbA
1991
Gelation of deoxygenated solutions of sickle-cell human Hemoglobin (HbS) is of high theoretical interest and it has serious pathological consequences. For this reason HbS is probably the most studied protein capable of self-organization. This notwithstanding, the location in the T, c plane of the region of thermodynamic instability of solutions of deoxy-HbS (as bounded by the spinodal line and as distinct from the gelation region) has remained unknown, along with related values of Flory-Huggins enthalpies and entropies. In the present work this information is derived from experiments for the two cases of (deoxy) HbS and of human adult hemoglobin (HbA). Experiments also show critical exponen…
HOW TO MAKE A PIE: REPRODUCIBLE RESEARCH FOR EMPIRICAL ECONOMICS AND ECONOMETRICS
2020
Les recherches empiriques en sciences humaines et sociales necessitent la manipulation de nombreux fichiers : differents jeux de donnees, de multiples programmes, qu'ils soient destines a la manipulation de donnees, aux traitements statistiques, aux estimations econometriques ou a des simulations, et de nombreux fichiers successifs de resultats. Maitriser l’ensemble des etapes du projet de recherche est indispensable si l’on souhaite pouvoir reproduire ou repliquer les resultats a long terme. Cette rigueur (fiabilite, tracabilite, reproductibilite), est desormais de plus en plus exigee par notre profession ainsi que par les editeurs de revues scientifiques. Apres avoir mis en evidence les e…
Water capillary absorption in porous media in different wettability conditions studied by Quantitative MRI and X-ray CT
2007
X-ray computed tomography (CT) and magnetic resonance imaging (MRI) have been successfully applied to study both the capillary properties of several samples of Lecce stone and the performances of treatments used for protection and conservation of historical stone artifacts. The presence of water inside the sample may be visualized by both MRI and X-ray CT. For the treated samples, the different dynamics of water absorption gives indirectly the efficacy of the polymer in the rock.
Integrated methodologies for qualitative and quantitative characterization of historical pigments
2014
From Land Reform to Hyperinflation: The Zimbabwean Experience of 1997-2008
2018
This article has for objective to contribute to the understanding of the Zimbabwean hyperinflation. The agrarian reform announced in November, 1997 is at the origin of this hyperinflation. This led to a massive outflow of capital and a disruption in the production that cause over several years the degradation of the foreign accounts, and a trend depreciation of the Zimbabwean dollar. The depreciation, via the increase of the costs in the import, cause the strong increase in prices. The long-lasting increase in prices have, subsequently, lead practice of price indexation on the foreign exchange rate. These phenomena of indexation not only fed the inflationary process, but also led to the col…